Two sensors in one

Introduction

Researchers at the Massachusetts Institute of Technology (MIT) have developed a nanoparticle that enables both magnetic resonance imaging (MRI) as well as fluorescent imaging in living animals.  The researchers believe that a single nanoparticle capable of performing these two functions should be able to help track specific molecules through the body, monitor a tumor’s environment, and determine whether drugs have reached their intended target.

In research published in the journal Nature Communications, the MIT team combined an MRI contrasting agent called nitroxide and a fluorescent molecule called Cy5.5 to produce a nanostructure called a branched bottlebrush polymer. The ratio of the two materials in the nanoparticle is 99 percent nitroxide and 1 percent Cy5.5.

This combination enables both MRIs and fluorescent imaging because of the interesting way these materials interact with each other. The nitroxides are reactive molecules in which a nitrogen atom is bound to an oxygen atom with one unpaired electron. Typically, the nitroxides suppress the Cy5.5’s fluorescence, except when the nitroxides are in the presence of molecule from which they can grab an electron, which, in the case of this study, was a vitamin C molecule. Once the free electrons in the nitroxides bind with the free electrons from another molecule, the MRI signal switches off and the Cy5.5 fluoresces.

Fluorescent imaging

Basic Principle of Fluorescence

In short, the basic principle of fluorescence entails the following (Figure 1): A photon with the energy hν_ex, is supplied by an external source, usually a laser of well-defined wavelength, and is absorbed by a fluorescent molecule. The absorption raises its energy level to an excited, unstable electronic singlet state (S₁‘) as depicted by the green arrow. This excited state is rather instable and thus has a very short lifetime. The excited fluorescent molecule relaxes towards the lowest vibrational energy level within the electronic excited state (S₁), loosing the energy in the form of heat (yellow arrow). Fluorescence emission originates from the drop from the excited state S₁to the ground state S₀ (red arrow). The energy of the photon that is emitted in this process, hν_em, is exactly the difference between S₁ and S₀. For most fluorophores used in biological applications the light emitted is at a characteristic wavelength that is determined by the difference in energy between S₁ and S₀.

Preparation of Specimen for Fluorescent Imaging

Since a cell’s endogenous molecules usually do not fluoresce themselves, the fluorescent marker has to be introduced. We use a variety of methods to effectively label different compartments and molecules of cells. Firstly, we use fluorescent dyes that are directly taken up by the cell. For example, we use DAPI (4′,6-diamidino-2-phenylindole) that strongly binds to A-T rich regions of DNA and therefore can be used to visualize the DNA content of cells (Figure 3, upper left panel). Secondly, we make use of immunofluorescence, a technique used to very specifically stain one target molecule, usually a protein. Fixed cells are incubated with a primary antibody raised against the protein of interest. This antibody is either labeled with a fluorophore directly or a secondary, labeled antibody is applied to amplify the fluorescent signal (Figure 3, upper right panel). In a similar manner we can detect specific sequences of DNA or RNA, with probes that hybridize to the sequence of interest with a method called FISH (fluorescence in situ hybridization). Similar to immunofluorescence, the probe is either labeled with a fluorophore directly or a secondary step is needed to stain the probe and detect the sequence of interest (Figure 3, bottom panel). Thirdly, we transfect cells with exogenous constructs expressing the protein of interest tagged with a fluorescent marker, e.g. GFP (green fluorescent protein). This method is heavily used to determine the location of the fusion protein in living cells over time, to determine its mobility and its interaction with other cellular components in the cell.

Example of application

Reference:

http://spectrum.ieee.org/nanoclast/biomedical/imaging/a-single-nanoparticle-enables-two-different-medical-imaging-techniques

http://malone.bioquant.uni-heidelberg.de/methods/imaging/imaging.html

My comment:

In the lecture, we have learned about the generation of PET & CT images in a single study, which can provide anatomic data from CT and metabolic data from PET at the same time.

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As for this new technology, it is a combination of MRI and fluorescent imaging, with help of a nanoparticle. I think the key point in this new technology is the combination of “an MRI contrasting agent called nitroxide “and “a fluorescent molecule called Cy5.5” producing a nanostructure called a branched bottlebrush polymer. As shown in the context, the interesting these materials interact with each other enables the switch between two imagings.

With the development of science and technology, “efficiency” is becoming one of main concerns. Ability to handle multiple tasks dose not only save us time but also provide a more clear comprehensive perspective, which could mean a lot in medical field.

Biosensor technology could allow rapid detection of Ebola virus

optofluidic nanoplasmonic sensor

Abstract on operating principle.

Fast and sensitive virus detection techniques, which can be rapidly deployed at multiple sites, are essential to prevent and control future epidemics and bioterrorism threats.

This label-free optofluidic nanoplasmonic sensor that can directly detect intact viruses from biological media at clinically relevant concentrations with little to no sample preparation.This sensing platform is based on an extraordinary light transmission effect in plasmonic nanoholes and utilizes group-specific antibodies for highly divergent strains of rapidly evolving viruses. So far, the questions remain for the possible limitations of this technique for virus detection, as the penetration depths of the surface plasmon polaritons are comparable to the dimensions of the pathogens.

Background

In 2010, Ahmet Ali Yanik published his first paper on the rapid detection of Ebola virus using new biosensor technology he and colleagues at Boston University had invented. But he found there was little interest at the time in developing the technology further.

Now, however, Ebola hemorrhagic fever has captured the attention of first world countries in a big way. The current outbreak in West Africa began spreading out of control just as Yanik was setting up his lab as a new faculty member at UC Santa Cruz, where he is an assistant professor of electrical engineering. Yanik plans to resume his work on virus detection in addition to ongoing projects involving biosensors for other biomedical applications. The current Ebola crisis may subside before his technology can be perfected, since there are still many challenges to overcome, but the need will remain for simple and inexpensive virus detection techniques, he said.

“The truth is that Lassa virus, which is related to Ebola and also causes hemorrhagic fever, infects nearly half a million people every year in Africa and kills more people than Ebola, but it doesn’t make the news. So there has been an ongoing crisis with hemorrhagic fever viruses, and now it’s finally getting some serious attention,” Yanik said.

His goal is to create a low-cost biosensor that can be used to detect specific viruses without the need for skilled operators or expensive equipment. “We need a platform for virus detection that is like the pregnancy tests you can use at home,” Yanik said. “The initial symptoms of hemorrhagic fever are similar to the flu, and you just cannot treat every person with flu symptoms as a potential Ebola-infected patient. It needs to be simple and cheap.”

Nanotechnology

Nanotechnology may provide a solution. Advances in nanotechnology have enabled researchers to fabricate novel materials with precise structures on the scale of nanometers (a nanometer is one billionth of a meter). A “plasmonic nanohole,” for example, is a tiny hole a few hundred nanometers across. Yanik’s2010 paper described a biosensor based on arrays of nanoholes in a metallic surface that interact with light in predictable ways. Using antibodies on the sensor surface to bind specific viruses, the researchers showed that binding of the virus caused a detectable change in the color of light transmitted by the nanohole arrays.

Detecting the color change, however, required the use of a spectrometer. Yanik later figured out how to make a sensor that could be read with the naked eye, without any need for electronic instruments. “You can use sunlight as the light source and the human eye as the detector,” he said.

He published that technique in a 2011 paper in the Proceedings of the National Academy of Sciences. The sensor technology involves realms of physics far more complex than the relatively straightforward enzymatic reactions involved in a pregnancy test. Light transmission through nanohole arrays occurs through a phenomenon known as “surface plasmon resonances,” which involves the oscillations of free electrons in a metallic surface. Yanik’s 2011 paper showed that light transmission could be greatly enhanced by exploiting a phenomenon called Fano resonances (named for Italian physicist Ugo Fano).

Label-free detection

“This effect causes a huge difference in light transmission that you can see with the naked eye,” Yanik said. Unlike conventional laboratory tests such as PCR and ELISA (currently the standard tests for Ebola infection), Yanik’s approach does not rely on labeling with fluorescent tags or other markers to see the results. “The results can be read immediately after the pathogen binds to the sensor,” he said.

Further work is needed, however, to improve the sensitivity of the sensor to the point where it could be effective for virus detection in routine “point-of-care” clinical evaluations.

reference:

http://pubs.acs.org/doi/abs/10.1021/nl103025u

http://news.ucsc.edu/2014/10/biosensor-technology.html

My Comment:

Personally I think this is a very good photoelectric sensor example (also using nanotechnology). It feels similar with what professor has showed us in previous lecture about DNA catching device. But the difference and maybe the most exciting part is that this biosensor is “label-free” which means “does not rely on labeling with fluorescent tags or other markers to see the results”.

In the lecture, we learned that it is usually very difficult to transform measure results into signals which can be detected, and our main methods solving this problem is making biomedical sensors into electronic devices,which can transfer quantities in biomedical fields into easily detectable electrical quantities. However, in this case, the result can be seen with naked eyes! So I think maybe one way to develop biosensor technology is to find easier way getting various signals, just like what Ahmet Ali Yanik did.

The wireless future of medicine

Wireless medicine encompasses devices, products, and technology that allow doctors, patients, and caregivers to diagnose and monitor health conditions, manage treatment more effectively, and speed up communication, decision time, and intervention.

Some Amazing Wireless Devices

Zio patch

Cardiac arrhythmias are common, but can be difficult to diagnose due to their sparse and fleeting occurrences. Since the 1960s, the gold standard for their diagnoses has been the Holter monitor, a “portable” ECG-type device with 5 to 7 leads connected to a central processing unit, which continuously records electrical cardiac activity to help spot abnormal signals over an extended time period. Due to its bulky size and numerous leads, the Holter monitor has been a nuisance for its wearers.  Researchers at the Scripps Translational Science Institute (STSI) have published a study that shows the small, wearable wireless ZIO Patch (iRhythm Technologies, San Francisco, CA) is better at diagnosing arrhythmias than the bulky Holter monitor, and also preferred by patients, potentially paving a new way for ambulatory heart monitoring.

The FDA-cleared ZIO Patch is a small, adhesive, water-resistant one lead ECG sensor that the user can stick onto their chest for a continuous 24-hour monitoring over 2 weeks.  It sports hydrogel electrodes for clearer ECG tracings and a button to capture symptomatic events.  At the end of the 2 weeks, the patch must be sent back to iRhythm for a full analysis using the ZIO Service’s proprietary algorithms, and a diagnostic report is then relayed to the patient’s physician.

minION

The MinION™  device is a small instrument that is compatible with consumable flow cells containing the proprietary sensor chip, Application-Specific Integrated Circuit (ASIC) and nanopores that are needed to perform a complete single-molecule sensing experiment. Plugging directly into a laptop or desktop computer through a USB port, it is a self-contained device to deliver real-time experimental data.

The MinION device is adaptable for DNA sequencing, protein sensing and other nanopore sensing techniques.  Currently, several hundred participants in the MinION Access programm (MAP) are working with the MinION system to explore how its features – including long read lengths, real time digital data, portability and compressed workflows – might help to answer a range of biological questions.  The MAP initially focuses on DNA analysis.

The MinION is operated using MinKNOW^TM software and participants in MAP will be performing basecalling in real time in the cloud, with the option to perform these analyses locally in the future.

Oxford Nanopore is focused on delivering the simplest possible sample preparation and workflows. The system is designed to be compatible with complex samples such as blood or serum and environmental samples such as water samples.

Artificial Lens

University of Washington engineers have designed a low-power sensor that could be placed permanently in a person’s eye to track hard-to-measure changes in eye pressure. The sensor would be embedded with an artificial lens during cataract surgery and would detect pressure changes instantaneously, then transmit the data wirelessly using radio frequency waves.

The researchers recently published their results in the Journal of Micromechanics and Microengineering and filed patents on an initial prototype of the pressure-monitoring device.

Reference:

https://nanoporetech.com/technology/the-minion-device-a-miniaturised-sensing-system/the-minion-device-a-miniaturised-sensing-system

http://www.washington.edu/news/2014/06/16/sensor-in-eye-could-track-pressure-changes-monitor-for-glaucoma/

http://www.medgadget.com/2014/01/zio-wireless-patch-may-be-better-option-than-holter-monitors-for-cardiac-arrhythmia-diagnosis.html

http://online.wsj.com/articles/SB10001424052702303404704577311421888663472

My Comment:

This is so COOL! I can’t wait to live in this wireless future.

I still remember in Burnice’s blog, she showed us that just by doing a simple ECG test in the ambulance car can rise chance of survival, but sadly a small group of people are not willing to do so.I think one of the reasons is that there are too many plugs need to be pinned all over chest. What a shame that people die because of shyness or inconvenience! Wireless devices can solve this problem easily.

Except for lower cost, convenience, the most inportant reason I find it very vital to our health is that it can give us real time data, which means you can monitor your health status any time you want. This is very important for preventing getting disease, or having a control on it before it becomes to bad that you have rush to hospital in an ambulance. Just as a  Chinese proverb  “Take precautions”

Body parts on a chip

It’s relatively easy to imagine a new medicine, a better cure for some disease. The hard part, though, is testing it, and that can delay promising new cures for years. In this well-explained talk, Geraldine Hamilton shows how her lab creates organs and body parts on a chip, simple structures with all the pieces essential to testing new medications — even custom cures for one specific person.

Two main ways testing drugs

Animal testing

What is animal testing?

The term “animal testing” refers to procedures performed on living animals for purposes of research into basic biology and diseases, assessing the effectiveness of new medicinal products, and testing the human health and/or environmental safety of consumer and industry products such as cosmetics, household cleaners, food additives, pharmaceuticals and industrial/agro-chemicals. All procedures, even those classified as “mild,” have the potential to cause the animals physical as well as psychological distress and suffering. Often the procedures can cause a great deal of suffering. Most animals are killed at the end of an experiment, but some may be re-used in subsequent experiments.

What’s wrong with animal testing?

For nearly a century, drug and chemical safety assessments have been based on laboratory testing involving rodents, rabbits, dogs, and other animals. Aside from the ethical issues they pose—inflicting both physical pain as well as psychological distress and suffering on large numbers of sentient creatures—animal tests are time- and resource-intensive, restrictive in the number of substances that can be tested, provide little understanding of how chemicals behave in the body, and in many cases do not correctly predict real-world human reactions. Similarly, health scientists are increasingly questioning the relevance of research aimed at “modelling” human diseases in the laboratory by artificially creating symptoms in other animal species.

Cell Testing

Stem cells take root in drug development

Stem cells have assumed near-mythical status in the popular imagination as a possible cure for every disease under the sun. But while public attention has focused on their potential in regenerative medicine, stem cells have quietly gained a foothold in drug development — a move that may hail a huge but unheralded shake-up of the biological sciences.

“I think there are tremendous parallels to the early days of recombinant DNA in this field,” says James Thomson, director of regenerative biology at the Morgridge Institute for Research in Madison, Wisconsin, and one of the founders of Cellular Dynamics International, also in Madison. “I don’t think people appreciated what a broad-ranging tool recombinant DNA was in the middle ’70s.” At the same time, he says, they underestimated the difficulty of using it in treatments.

Now stem cells are in a similar situation, he says, and although therapeutic use is likely to come to fruition eventually, “people underappreciate how broadly enabling a research tool it is”, he says.

Drug companies began dipping a tentative toe into the stem-cell waters about two years ago . Now, the pharmaceutical industry is increasingly adopting stem cells for testing the toxicity of drugs and identifying potential new therapies, say those in the field.

Cellular Dynamics sells human heart cells called cardiomyocytes, which are derived from induced pluripotent stem (iPS) cells. Thomson says that “essentially all the major pharma companies” have bought some. The company also produces brain cells and cells that line blood vessels, and is about to release a line of human liver cells.

A brand new way ( more than drug testing )–Body parts on a chip.

With her(Geraldine Hamilton) colleagues at Harvard’s Wyss Institute Geraldine has developed the Organ-on-a-Chip. The chip’s goal is to represent the function and mechanical strain that is placed on cells in an environment using actual human cells.

Inspiration comes from the manufacture of computer chips to build the chips. Three channels exist within the chips, beginning with a thing membrane in the center that holds the human cells. Mechanical forces can then be applied to the outside of these cells to simulate tension, compression, temperature changes or fatigue. Channels exist above and below the cell to circulate air and blood.

Hamilton shows an example of white blood cells attacking bacteria in a simulated lung using computer graphics and then shows the process live inside a chip environment. Current projects include simulated livers, guts, lungs, hearts and bone marrow. Each chip is different to simulate the function and constraints of the individual organ.

One future goal is to be able to connect all of these organs together and simulate a Human-on-a-Chip. Discovering a lung side effect when testing a heart medicine will be invaluable if it happens before human clinical testing. Makeup, chemical cleaners, biohazard combat and drug delivery can all benefit from full system testing.

Reference:

http://www.hsi.org/campaigns/end_animal_testing/qa/about.html

http://www.nature.com/news/stem-cells-take-root-in-drug-development-1.10713

http://www.engineering.com/DesignerEdge/DesignerEdgeArticles/ArticleID/6769/Harvard-Scientists-Create-Organs-on-a-Chip.aspx

https://www.dosomething.org/facts/11-facts-about-animal-testing

My comment:

When we were talking about microfluid in class, professor showed us a very amazing picture of ” lung-on-a-chip”. The idea of “put” human body parts greatly sparks my interests. So here I want to share this video and its relative information with you.

First, let’s talk about two main traditional ways for testing. For animal testing, it is seems very straight forward and important to me,  because animals and we human beings share some common factors, both are living things made up by cells. Although there are huge differences in structure and function, it at least helps us assessing the basic effectiveness of new medicinal products. However, ethical issues could be an extreme limitation for this method. And for the cell testing, actually I think it is a bright way, especially when using stem cell as mentioned above. Although we can not provide exact the same environment for cells as in human body.

Next, when it comes to the new method, I think it is very creative. I will skip the introduction here because everything is clearly elaborated in the video. I just want to say that the idea of personalise is really fantastic. Think about it, we are all human beings but we differ from each other very much, the same drug can impact different effects. If we can have our personal chip, numerous fatal tragedy caused by the allergy can be avoided. Nowadays health care are attracting more and more attention, this personal idea has unlimited bright future.

Amblyopia treatment — happiness comes with better vision

What is amblyopia?

Amblyopia is a condition where the vision in an eye is poor because of lack of use of the eye in early childhood. In most cases, only one eye is affected, but it sometimes affects both eyes. Amblyopia is often called a lazy eye. In some cases of amblyopia caused by anisometropia (see below), the problem can sometimes be corrected by glasses. In most cases, however, glasses do not help.

Why is amblyopia important?

If you have permanent amblyopia, you do not see properly out of one eye. The severity of visual impairment can vary. Although you can see well enough out of one eye to get by, it is always best to have two fully functioning eyes.

Even with mild amblyopia you may not have a good sense of depth when looking at objects (you cannot see properly in three dimensions). You cannot do some jobs if you have good vision in only one eye. If you only have good vision in one eye, you risk severe sight problems if you have an injury or disease of the good eye later in life. So, treatment is usually always advised if it is likely to restore vision.

What are the treatments for amblyopia?

Two directions

• Correcting any underlying eye disorder, such as strabismus (squint), or correcting refractive errors (for example, long or short sight).
• Training the amblyopic eye to work properly, so that vision can develop correc

Correcting the underlying eye disorders

Refractive errors such as short or long sight can be corrected with glasses. Cataracts can be treated with an operation. Improvement in eyesight after being fitted with glasses for a refractive error can take 4 -6 months.

Making the affected eye work

The most common treatment for amblyopia is eye patching. This is where the good eye is covered with an eye patch, forcing the amblyopic (lazy) eye to see. Eye patches are soft, with sticky edges that fix them to the skin surrounding the eyelids. Eye patching is also called occlusion.

Other treatments for amblyopia include eye drops and glasses. Occasionally, eye drops are used to blur the vision in the good eye instead of an eye patch. Eye drops can be useful when a child refuses to wear a patch. Once drops are put in a child’s eye, the child can’t change the blurring of vision; it simply wears off after time. You might have to put the drops in your child’s eye each day, but sometimes it can be done just at weekends. Some people find it difficult to hold their child and put drops in the eye. With practice, both you and your child can get used to using eye drops. From a cosmetic viewpoint, using eye drops is less obvious than an eye patch. The eye drops used to blur the vision usually contain a medicine called atropine. This can occasionally cause side-effects such as eye irritation, flushing (reddening) of the skin, a fast heartbeat (tachycardia) and hyperactivity.

Vision therapy can be used as a treatment to maintain the good work achieved by eye patching. This involves playing visually demanding games with a child to work the affected eye even harder – like eye training. Your child should do close-up activities when wearing a patch or using other amblyopia treatments. Activities such as drawing and colouring, reading and school work are detailed and work the eye well.

Reference:

http://www.patient.co.uk/health/amblyopia-leaflet.

http://wowvision.net/about

My comment:

I have to admit that I am shocked at the universality of amblyopia. Statistic shows that about 1 in 25 children develop some degree of amblyopia, which is also mentioned in the video, around 3%. What’s more, from the introduction above I also learned that amblyopia can bring much greater adverse impact to life than I thought. So a good therapy seems to be badly needed under this condition.

We know that basically, there are three main methods, eye patch, eye drop and glasses and vision therapy. The first two could be sorted into occlusion therapy category, and “vision therapy” is binoculars. According to the speaker in the video, he thinks that “binoculars vision therapy is more right”. I agree with him at this point for the following reason:

Personally I think the most important part of rehabilitation is help patients to regain the ability to control their “broken parts” instead of relying on some instruments or drugs. (In this case, eye patch or eye drop). The vision therapy involves feedback. It just like a negative feedback regulation in our body, doctors can change training methods and workload （input) according to patients performance.(output) Patients are actively learning in this procedure, so we have ground to believe this is a more effective way.

Regenerative medicine — to make patients better

Anthony Atala: Growing new organs

Anthony Atala’s state-of-the-art lab grows human organs — from muscles to blood vessels to bladders, and more. In this vedio ,he shows footage of his bio-engineers working with some of its sci-fi gizmos. Let’s see what exactly these very tough technologies are.

Smart biomaterials

In its simplest form a tissue engineering (TE) scaffold provides mechanical support, shape, and cell-scale architecture for neo-tissue construction in vitro or in vivo as seeded cells expand and organize. Most degradable biomaterials used to date comprise a class of synthetic polyesters such as poly(l-lactic acid) (PLLA) and poly(l-glycolic acid) (PLGA), and/or natural biological polymers such as alginate, chitosan, collagen, and fibrin. A multitude of fabrication techniques have been devised and afford an abundance of potential shapes, sizes, porosities, and architectures and. Composites of these synthetic and natural polymers, alone or with bioactive ceramics such as hydroxyapatite or certain glasses, can be designed to yield materials with a range of strengths and porosities, particularly for the engineering of hard tissues .

It has become increasingly apparent that for many TE applications biomaterial scaffolds should provide more than temporary architectural structure to a developing tissue construct. As cell and molecular biology converge with materials science and biomedical engineering, new applications in regenerative medicine will benefit from interactive biomaterials that serve to orchestrate cell attachment and growth, as well as tissue morphogenesis. However, many of the same tools developed for evaluating the biocompatibility of traditional biodegradable polymers are still used to investigate the fundamental interactions between new classes of biomaterials and their host and. Importantly, quantitative methods of assessing host tissue response to extracellular matrix (ECM) biomaterials such as collagen can also be employed.

3D printed organs

In a major medical breakthrough, researchers from Sydney and Harvard universities have managed to 3D bio-print capillaries, the tiny channels that allow vascularisation to take place so that cells can sustain themselves and survive.Using a high-tech “bio-printer”, the researchers fabricated tiny, interconnected fibres to serve as the mould for the artificial blood vessels.They then covered the 3D printed structure with a cell-rich protein-based material, which was solidified by shining light on it.Lastly they removed the bio-printed fibres to leave behind a network of tiny capillaries coated with human endothelial cells, which formed stable blood capillaries in less than a week

Decellularized organs

Decellularization is the process of taking an existing organ and stripping its cells, leaving the intricate skeleton of the extracellular matrix intact. That can then be repopulated by a patient’s own cells to recreate a donor organ for transplant, though only a few organs have been successfully rebuilt in this way so far. As a technique this has many advantages over simple transplants: it removes the possibility of immune rejection, makes the use of animal organs practical, and rehabilitates donor organs that would otherwise be unsuitable

kidney as an example :

kidneys from deceased donors are thrown away each year due to damage. Apaper  earlier this month suggests that they could be put to use as raw material for engineering new kidneys. The study’s authors treated discarded human kidneys with a detergent, which cleared the organ of cells and left only the cells’ extracellular matrices. The eventual plan is to grow the patients’ own cells on the scaffold, producing a kidney that the patients would be less likely to reject than an ordinary transplant. “These kidneys maintain their innate three-dimensional architecture, their basic biochemistry, as well as their vessel network system.”

The scientists tested the scaffold for antigens that might cause a patient to reject the organ and found that they had been eliminated along with the cells. When the researchers transplanted the modified kidneys into pigs and connected their vasculature to the pigs’ circulatory systems, blood pumped through the kidneys at normal pressure. “With about 100,000 people in the U.S. awaiting kidney transplants, it is devastating when an organ is donated but cannot be used. These discarded organs may represent an ideal platform for investigations aimed at manufacturing kidneys for transplant.”

references:

http://www.sciencedirect.com/science/article/pii/S0142961207005625

http://www.theguardian.com/science/2014/jul/04/3d-printed-organs-step-closer

https://www.fightaging.org/archives/2013/05/decellularization-may-enable-use-of-more-donor-organs.php

Comment:

I have to say this is really a very inspirational talk. All these amazing technologies make me want to believe there will be one day we human being never be bothered by those getting sick or aging even dying issues any more. And I know that it is actually not easy to achieve these results, as Pro.Anthony Atala mentioned in the video “so, these are very tough technologies. Once you get the formula right you can replicate it. But it takes a lot to get there.”  Technologies we learn from that video which make us want to cry out with surprise cost decades for scientists to develop. Moreover, after that, they need to test it in the lab for maybe a thousand times before they use it on patients. But isn’t this tortuous process that makes people really feel the beauty of life and cherish it more?

Besides, I am most impressed by the sentence”And when we launch these technologies to patients we want to make sure that we ask ourselves a very tough question. Are you ready to place this in your own loved one, your own child, your own family member, and then we proceed.”  Wide arrange of knowledge and perfect skills make a good scientist, but conscience and responsibility make respected one.

Balance mattars !

Homeostasis song : p

5 Common Examples of Homeostasis in the Human Body

Acid-Base Balance

The body controls the amounts of acids and bases in the blood. When the number of acidic compounds in the blood increases, body acidity also increases. This occurs when someone consumes or produces more acidic compounds or when the body fails to eliminate acidic compounds. When the number of alkaline compounds in the blood increases, body alkalinity increases. Acid-base balance refers to the balance between alkalinity and acidity in the blood, as measured on the pH scale. The kidneys and lungs, along with buffer systems, help control acid-base balance.

The kidneys excrete excess acids and bases. Kidney damage may reduce the ability of the kidneys to excrete these substances, leading to a disturbance in acid-base balance. The lungs control pH levels by excreting carbon dioxide. When a person exhales, the diaphragm pushes carbon dioxide out of the body. The pH of the blood changes when the depth and speed of breathing change, making it possible to adjust blood pH in less than a minute. Buffer systems prevent sudden changes in acidity and alkalinity. These systems consist of weak acids and weak bases that occur naturally in the human body.

Body Temperature

 

Another one of the most common examples of homeostasis in humans is the regulation of body temperature. Normal body temperature is 37 degrees C or 98.6 degrees F. Temperatures way above or below these normal levels cause serious complications. Muscle failure occurs at a temperature of 28 degrees C or 82.4 degrees F. At 33 degrees C or 91.4 degrees F, loss of consciousness occurs. At a temperature of 42 degrees C or 107.6 degrees F, the central nervous system starts to break down. Death occurs at a temperature of 44 degrees C or 111.2 degrees Fahrenheit. The body controls temperature by producing heat or releasing excess heat.

Glucose Concentration

Glucose concentration refers to the amount of glucose – blood sugar – present in the bloodstream. The body uses glucose as a source of energy, but too much or too little glucose in the bloodstream can cause serious complications. The body uses hormones to regulate glucose concentration. Insulin reduces glucose concentration, while cortisol, glucagon and catecholamines increase glucose concentration.

Calcium Levels

The bones and teeth contain approximately 99 percent of the calcium in the body, while the other 1 percent circulates in the blood. Too much calcium in the blood and too little calcium in the blood both have negative effects. If blood calcium levels decrease too much, the parathyroid glands activate their calcium-sensing receptors and release parathyroid hormone. PTH signals the bones to release calcium to increase the amount of calcium in the bloodstream. If calcium levels increase too much, the thyroid gland releases calcitonin and fixes more calcium in the bones. This decreases the amount of calcium in the blood.

Fluid Volume

The body has to maintain a constant internal environment, which means it must regulate the loss and gain of fluid. Hormones help to regulate this balance by causing the excretion or retention of fluid. If the body does not have enough fluid, antidiuretic hormone signals the kidneys to retain fluid and decrease urine output. If the body has too much fluid, it suppresses aldosterone and signals the excretion of more urine.

My comment:

We can compare our body to a huge chemical plant, countless biochemical reactions are taking place at the same time. If we want to maintain a good running condition, keep those reactions taking place in order, which is essential to our survival, we must provide them a suitable environment– homeostasis,which is a concept about balance.

As far as I know , many diseases are a result of homeostatic imbalance or an inability of the body to restore a functional and stable internal environment. One common example is “diabetes”.A group of metabolic diseases whereby a person (or other animal) has high blood sugar due to an inability to produce, metabolize, or respond to the hormone insulin.

Genes do play a role in  diabetes, but lifestyle choices are also important. You can, for example, have a genetic mutation that may make you susceptible to type 2, but if you take good care of your body, you may not develop diabetes. So it is very important for us to chose a health lifestyle, exercise more, eat balance, keep our “chemical plant” in a good condition!

References

Merck Manuals Home Edition: Acid-Base Balance

University of Cincinnati: Body Temperature Regulation

MSN Health: How the Body Controls Blood Sugar

Colorado State University: Endocrine Control of Calcium and Phosphate Homeostasis

The Merck Manual of Medical Information: Water Balance

Photo Credit: PhotoSpin

http://www.endocrineweb.com/conditions/type-2-diabetes/type-2-diabetes-causes

The key to AGING –Telomere

How do our cells have DNA left?–because of telomeres

  

       

         

What is telomere?

A telomere is a region of repetitive nucleotide sequences at each end of a chromatid, which protects the end of the chromosome from deterioration or from fusion with neighbouring chromosomes. Its name is derived from the Greek nouns telos (τέλος) ‘end’ and merοs (μέρος, root: μερ-) ‘part.

Why do telomeres get shorter each time a cell divides?

Before a cell can divide, it makes copies of its chromosomes so that both new cells will have identical genetic material. To be copied, a chromosome’s two DNA strands must unwind and separate. An enzyme (DNA polymerase) then reads the existing strands to build two new strands. It begins the process with the help of short pieces of RNA. When each new matching strand is complete, it is a bit shorter than the original strand because of the room needed at the end for this small piece of RNA. It is like someone who paints himself into a corner and cannot paint the corner.

Telomeres and aging

Telomeres play a central role in cell fate and aging by adjusting the cellular response to stress and growth stimulation on the basis of previous cell divisions and DNA damage. At least a few hundred nucleotides of telomere repeats must “cap” each chromosome end to avoid activation of DNA repair pathways. Repair of critically short or “uncapped” telomeres by telomerase or recombination is limited in most somatic cells and apoptosis or cellular senescence is triggered when too many “uncapped” telomeres accumulate. The chance of the latter increases as the average telomere length decreases. The average telomere length is set and maintained in cells of the germline which typically express high levels of telomerase. In somatic cells, telomere length is very heterogeneous but typically declines with age, posing a barrier to tumor growth but also contributing to loss of cells with age. Loss of (stem) cells via telomere attrition provides strong selection for abnormal and malignant cells, a process facilitated by the genome instability and aneuploidy triggered by dysfunctional telomeres. The crucial role of telomeres in cell turnover and aging is highlighted by patients with 50% of normal telomerase levels resulting from a mutation in one of the telomerase genes. Short telomeres in such patients are implicated in a variety of disorders including dyskeratosis congenita, aplastic anemia, pulmonary fibrosis, and cancer.

My comment:

How and why we age probably is one of the greatest mysteries in modern science, but unfortunately until now we still can not give an exact answer to this important question concerning to our health. Without knowing this, basically what we are doing now is just what a handy man does, we keep patching cracks rather than fixing the foundation.

Telomere theory is one possible answer to this question, which connects the shorten of telomeres at ends of chromosome with cell aging. The mechanism is clearly explained in the above context, which I found very convincing

For any theory, it needs some hard evidences to prove its validity. Discoveries about “how chromosomes are protected by telomeres and the enzyme telomerase” made by  Elizabeth H. Blackburn, Carol W. Greider and Jack W. Szostak provides us one for the telomere theory, which wins “The Nobel Prize in Physiology or Medicine 2009″

So I guess now I can understand a little why people say that ” the development of science is spiralling”. Maybe we can not find out the final answer for the time being ,and we will encounter some huge difficulties during the study. But by the efforts of generations after generations, we should believe that one day, we human beings can fully understand everything !

references:

http://www.nobelprize.org/nobel_prizes/medicine/laureates/2009/press.html

http://learn.genetics.utah.edu/content/chromosomes/telomeres/

http://en.wikipedia.org/wiki/Telomere#Cancer

http://www.ncbi.nlm.nih.gov/pubmed/18391173

Gene-silencing drug at forefront in battle against Ebola

What is the Ebola virus?

Most people’s views of Ebola are probably informed by Hollywood — they think of it as a deadly and contagious virus that swirls around the world, striking everyone in its path and causing them to hemorrhage from their eyeballs, ears and mouth until there is no more blood to spill.

In reality, Ebola is something quite different. About half of the people who contract Ebola die. The  others return to a normal life after a months-long recovery that can include periods of hair loss, sensory changes, weakness, fatigue, headaches, eye and liver inflammation.

About the blood: while Ebola can cause people to hemorrhage, about half of Ebola sufferers ever experience that Biblical bleeding that’s become synonymous with the virus.

More often than not, Ebola strikes like the worst and most humiliating flu you could imagine. People get the sweats, along with body aches and pains. Then they start vomiting and having uncontrollable diarrhea. These symptoms can appear anywhere between two and 21 days after exposure to the virus. Sometimes, they go into shock. Sometimes, they bleed. Again, about half of those infected with the virus die, and this usually happens fairly quickly — within a few days or a couple of weeks of getting sick.

Nor is Ebola as contagious as Hollywood would have you believe. You need to have contact with the bodily fluids — vomit or sweat or blood — of someone who is symptomatic and shedding the virus to get the disease. That’s why health-care workers and family caretakers who nurse the sick have borne the burden of Ebola.

The virus isn’t airborne, thankfully. Experts expect that it will never become airborne. As Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, told the Senate recently: “Very, very rarely does [a virus] completely change the way it’s transmitted.”

What makes Ebola scary is the fact that there is no cure or treatment yet on the market, but those who have access to hospital care — including fluids and antivirals — have a much higher chance of beating the disease. The trouble is, until now, Ebola always strikes in Africa — and among populations where few have access to that kind of advanced medical care.

Reference:

utube.com/watch?v=jn5CQDqP7mg

http://www.vox.com/cards/ebola-facts-you-need-to-know/what-is-the-ebola-virus

Comment:

Recently, this new kind of virus attracts lots of attention because of its high death rate and scary spread speed. Actually every time we human beings encounter a new kind of deadly disease, the first few months could always be very desperate and hopeless, until some new drug is found.

In this case, once we figure out the virus‘ pathogenic mechanism, we can directly develop drugs working on the gene. Personally, I strongly believe gene is the final solution to every problem related to living creature. And take what we have been learning into consideration, once you control the gene, you control the whole creature, because it is where all the proteins and other matters come.

Simple urine test detects cervical cancer virus !

Dread going for a smear test? A simple urine test can pick up the human papilloma virus (HPV) that causes cervical cancer. Though it’s not as accurate as sampling viral DNA from the cervix itself, the test might benefit women who are too busy or scared to have a cervical swab taken, or who live in developing countries where the infrastructure for conventional smear tests is less developed.

Traditional cytology-based smear tests involve using a speculum to hold the vagina open, while a small brush is used to collect cells from the cervix, which are then assessed for pre-cancerous changes using a microscope. “The advantage is that if you have an abnormal result, there is a reasonable chance that you have an underlying abnormality,” says Henry Kitchener at the Institute of Cancer Sciences in Manchester, UK, who was not involved in the current study.

More recently, DNA tests have been developed that test for HPV directly – again by taking a sample from the cervix. This is more sensitive than a conventional smear test meaning that those who test negative are very unlikely to develop cervical cancer in the near future. But those who test positive don’t necessarily have cancer – their cervix may be perfectly healthy – so a positive DNA test needs to be followed up with a physical examination.

Cancer screening

DNA testing for HPV is being piloted in the UK, and was recently incorporated into US guidelines for cervical cancer screening .

Neha Pathak at Barts and The London School of Medicine and her colleagues combined the results of 14 clinical trials of urine testing and compared the results against the new cervical DNA test. Urine tests could correctly identify 87 per cent of HPV positive samples, and 94 per cent of negative samples.

“It suggests urine testing is definitely something worth investigating further,” says Pathak.

Unfortunately, data doesn’t exist that would allow urine testing to be compared with more traditional smear tests – something Pathak says should be investigated in any future trials.

HPV tests for all

However, cervical HPV DNA testing is already known to be more sensitive than microscope-based methods. “It may be that the urinary HPV test is as good as a cytology sample,” says Kitchener.

Even so, urine-based HPV testing is unlikely to replace cervical HPV testing completely. “The actual test in itself isn’t a better test,” Kitchener adds. “But it is another way of obtaining results from the lower genital tract, and it may well be the way forward for women who don’t otherwise engage with screening.”

It could also be useful in developing countries where rates of cervical cancer are often far higher, and the infrastructure for screening and preventative treatment is lacking.

“We’re not saying that this is a direct replacement for cervical testing, but it is something that could be rolled out a little more easily,” Pathak says.

reference:

http://www.newscientist.com/article/dn26218-simple-urine-test-detects-cervical-cancer-virus.html#.VBvayy6Sx_E

My comment :

Personally I am very afraid of all those tests in the hospital, they all seem to be very scary and painful. So this is definitely an exciting news for my kind of people.

I think one purpose of developing biomedical engineering is to cure patients in a better way. Not only treat their diseases, but also treat it in a more comfortable way. So even though now some methods are already accurate enough, there is still room for improvement.

And there is another interesting point in this piece of news. That is about the accuracy. We learned that no matter which method we use, there is no way to be 100%-sure. And sometimes we’d rather choose a method with low accuracy, because accuracy is not the only standard of measuring an test method. So there are actually many considerations involved to choose one appropriate method.