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Dr. Marie Gabrielle Laguna

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Medical doctor-internist

https://www.eternusglobal.com

Newly evolved human gene variants are able to protect older adults from memory and cognitive deficits

Feb 3, 2016

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According to the University of California, San Diego School of Medicine, a variety of human gene variants have specifically evolved to avoid neurodegenerative and cardiovascular disease, thus preserving their contributions to society.

Ajit Varki, MD, who is a Distinguished Professor of Medicine and Cellular and Molecular Medicine at the UC San Diego School of Medicine, and the lead author of the study says that We unexpectedly discovered that humans have evolved gene variants that can help protect the elderly from dementia. Such genes likely evolved to preserve valuable and wise grandmothers and other elders, as well as to delay or prevent the emergence of dependent individuals who could divert resources and effort away from the care of the young.�

According to the standard model of natural selection, if the age of reproduction is passed, individuals die. The reason behind this is that selection in early life prefers variants that favor reproductive success, even if there will be consequences later in life, which is one major reason why we age. This case can be seen in almost all vertebrates. On the other hand, humans (and some species of whale), are actually exceptions to this rule, and can live decades beyond the age for reproduction. The elder population is able to contribute to this fitness of the younger generation by caring for the grandchildren and also help by passing down important cultural knowledge. Human aging is accompanied by cognitive decline, and unfortunately, this interferes with the benefits previously mentioned, and makes the elderly population a burden instead, because the younger population has to care for them.

Memory Loss Genes

Varki and his team cooperated with Pascual Gagneux, PhD, who is an associate professor of pathology
and associate director of CARTA, and his team. They focused on the expression of the CD33 protein, which
is a receptor that is seen in the surface of immune cells. The function of this receptor is to maintain
immune reactions, prevent self-inflicting damage, and also prevented unwanted inflammation. Studies
previously conducted have shown that a certain type of CD33 prevents amyloid-beta accumulation in the
brain, which is associated with Alzheimer's disease.

The researchers compared levels of CD33 in the brain to our closest living relatives, the chimpanzees. They
discovered that the levels of CD33 are around four-times higher in humans than in the primates.

Apart from CD33, the researchers also found human-specific variations in genes that are also involved in
the inhibition of cognitive decline. One of the genes that they found is APOE, but the ancestral form of
the genes, APOE4, is actually a risk factor for Alzheimer's and cardiovascular disease. However, other
variants such as APOE2 and APOE3 have actually evolved in order to prevent dementia.

Our study does not directly prove that these factors (negative effects of cognitive decline in elderly) were
involved in the selection of protective variants of CD33, APOE and other genes, but it is reasonable to
speculate about the possibility. After all, inter-generational care of the young and information transfer is
an important factor for the survival of younger kin in the group and across wider social networks or tribes,�
says Gagneux.

New study shows new treatment for children suffering from chronic pain

Feb 2, 2016

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A National Institutes of Health initiative has piloted a study that aims to help physicians better evaluate and treat children who are suffering from chronic pain. The study was done using face-to-face interviews with pediatric patients, giving the study a better view of how they see their lives to be.

In the current issue of the Journal of Pain, a paper was published by a collaboration between the University
of Cincinnati's Department of Anthropology, UC College of Medicine Department of Pediatrics, Emory University School of Medicine, and Cincinatti Children's Hospital Medical Center.

The interdisciplinary study was based on individual and group interviews with 32 pediatric patients with chronic pain. These include children who are suffering from juvenile arthritis, sickle cell anemia, and cerebral palsy, says Jeffrey Jacobson, the lead author and a UC associate professor of anthropology.

The main goal of the study was to determine the pain measures as made by the Patient Reported Outcomes Management Information System, abbreviated PROMIS, which is an initiative by the National Institutes of Health. PROMIS was created to make a set of freely available, widely applicable, and top-
notch patient-reported outcomes, which are measures that can be used within and across one patient's conditions throughout his or her lifetime.

Jacobson explains that pain is not something that can be really measured, and these values can only be acquired from reports made by patients. The study focused on children from ages 8-18 and how they talk about the pain that they experience and what kind of vocabulary they like to use during these times. We found that many questions or items from pain measures used with adults, describing pain as �gnawing or
suffocating', made younger children uncomfortable. They appeared to relate that to a monster or someone doing something to them. They also have a more limited vocabulary than adults, particularly in relation to the more abstract language of pain quality,� he added.

The papers states different categories of pain experience and what type of words children use when describing about the pain that they feel, and the fit of these categories with those used by PROMIS. For �Pain behavior', the patients describe that he or she becomes irritable or has no appetite when in pain. In �Pain interference', the children describe slower movement, for example in times when they walk, or lack of energy. Lastly, for �Pain quality', they describe pain as being sharp, dull, cutting or achy. The PROMIS
domains and those used by the patients were actually found to fit well.

Some children though, would say something like �I did better when the teacher gave me permission to be
a little late for class, because it takes me so long to get there'. So they're describing how they're managing
or coping with pain,� says Jacobson.

Other pain-coping strategies described by the children include self-distraction or exercise, as well as
cognitive coping methods such as keep going, save it for another day�.

Based on the results of the study, several recommendations were made to the PROMIS pain assessment
framework, such as dividing the pain quality into two types: pain-sensory and affective. The authors add that their results on coping with pain needs further studies for more recommendations to the PROMIS initiative.

New approach to treating arthritis discovered

Feb 1, 2016

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According to researchers from the Queen Mary University of London (QMUL), arthritis patients will be able to benefit from a new type of treatment.

The study that was performed showed that arthritic cartilage, which was until now thought to be unaffected by any kind of therapy, could be treated by a patient's own �microvesicles' which have the ability to travel into cartilage cells and deliver therapeutic agents.

Microvesicles are small subcellular structures that are 0.05 to 1 micrometer in diameter. They consist of a fluid enclosed by a membrane. These structures are released by cells in large numbers to transfer biological compounds such as lipids and proteins to target cells. However, their role in disease has not yet been completely understood. In most cases, the microvesicles of white blood cells accumulate in the joints of rheumatoid arthritis patients.

Cartilage has always been long thought to be impenetrable to cells and other small structures, and thus also impenetrable to therapy. Surprisingly, microvesicles coming from white blood cells are able to �travel' into the cartilage and are also able to deliver their cargo, which also has a protective effect on the cartilage.

Our study indicates that these vesicles could be a novel form of therapeutic strategy for patients suffering from cartilage damage due to a range of diseases, including osteoarthritis, rheumatoid arthritis, and trauma. Treating patients with their own vesicles may only require a day in the hospital, and the vesicles could even be �fortified' with other therapeutic agents,� said lead author Mauro Perretti from QMUL's William Harvey Research Institute.

The study was published in Science Translational Medicine and was funded by the organization Arthritis Research UK, the Nuffield Foundation (Oliver Bird Fund), and the Wellcome Trust. It examined the role of microvesicles in some mice models and human cartilage cells in which the researchers investigated their�effect on experimental arthritic disease.

Arthritis and Microvesicles

In their experiments, they used mice that were genetically modified to have reduced microvesicle production. Causing experimental inflammatory arthritis on these genetically modified mice exhibited cartilage damage. However, when these same mice were treated with microvesicles, the cartilage degradation was reduced. Doing similar experiments to human cartilage cells showed that the treatment of microvesicles also resulted in cartilage protection.

The researchers also found that one particular receptor was involved in these effects. The receptor, known as �FPR2/ALX', was shown to be involved in the protection of cartilage tissue. Because of its involvement, it could therefore be a good target for the treatment of cartilage-damaging arthritis-related seases with the use of small molecules.

By using the body's own transport system to get new and current therapeutic agents directly into the cartilage, holds the promise that we will be able to reduce joint damage more effectively than ever. A healthy and intact joint results in less pain and disability improving the quality of life of millions of people
living with arthritis in the UK,� said Stephen Simpson, who is Arthritis UK's Medical Director.
The researchers indicate that this may prove to be a new approach for the treatment for damaged
cartilage due to arthritis. Further studies in humans may also needed to confirm the actual therapeutic
potential of this new type of treatment.

Mastectomy and reconstruction not really a good combination for early breast cancer treatment

Jan 31, 2016

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A new study from the University of Texas MD Anderson Cancer Center reviewed treatment types for women with early breast cancer, and mastectomy and reconstruction had the most complications and complication-related costs.

The combination was also seen to be the most expensive treatment option�for younger patients.

The study was presented by Benjamin D. Smith, M.D., who is an associate professor of Radiation Oncology and Health Services Research, at the 2015 San Antonio Breast Cancer Symposium. The research serves to help patients and physicians to know what the best treatment options are, as well as determine which
treatment options give the best value for the money being paid by the patients.

Women who have early stage breast cancer have many guidance-concordant therapies to choose from.
These include: lumpectomy with whole breast irradiation (lump + WB) or brachytherapy (lump + brachy); mastectomy alone (mast alone) or plus reconstruction (mast + recon), or in older aged patients, lumpectomy alone (lump alone). All of these therapies give the same chances of survival, however, they
are different in terms of what the patient has to endure.

Smith says that when physicians talk with their patients, they usually explain that they will be able to receive treatments such as lumpectomy, whole breast irradiation or mastectomy, with or without reconstruction. On the other hand, the physicians themselves sometimes do not have a clear understanding of the pros and cons of each of these therapies.

Understanding the differences is quite important, especially because in the last ten years, the number of patients receiving mast + recon treatment has continued to increase in the United States, as reconstruction has become more accessible to patients. This study is the first to show that there is actually some form of harm involved in this treatment combination.

Breast Cancer Treatment Options

The researchers collected data from 2000-2011, from a total of 44,344 patients younger than 65 and 60,867 patients aged 66 and older. Data from the younger set of patients were taken from the MarketScan research database and the older generation from the SEER-Medicare database.

From the younger age bracket, mast + recon had the highest risk for complication, at 56%. The same was seen in the older population with a 69% risk of complication for mast + recon treatment. In terms of cost, in the younger generation, mast + recon was the most expensive, at an average of around $89,000. On the other hand, in the older patients, the most expensive form of treatment was lump + brachy, at around
$38,000, as compared to mast + recon at $36,000.

The study shows for the first time the fact that as patients undergo surgery, they may be taking more risks as to what could possibly happen. If the patient can have a lumpectomy and radiation, it may be a smoother course than going through a mastectomy, reconstruction and potentially other surgeries,� says Smith.

Comprehending this type of information is very important to those involved in health care. Despite the results of this research, though, Smith emphasizes that for some patients with early breast cancer, mast + recon is still the best option for treatment.

HIV/AIDS medication interfere with neuronal insulation

Jan 30, 2016

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A type of medication for patients with HIV/AIDS, called antiretroviral therapies, or ART, has enabled�those afflicted with the disease to live much longer lives. Unfortunately, around half of the patients�under this kind of treatment are experiencing cognitive impairment, such as memory loss, even though
the virus is practically undetectable in their bodies.

Researchers from the University of Pennsylvania and the Children's Hospital of Philadelphia have
collaborated in order to investigate the reason as to why these cognitive impairments are occurring. They
discovered that ARTs actually hamper the activity of oligodendrocytes, which are important cells found in
the brain that produce myelin, which is the insulating material of neurons. Myelin allows neurons to
transmit signals to and from the brain effectively and efficiently.

This specific effect of ARTs on myelin may be responsible for the cognitive deficiencies that HIV patients
experience, and may therefore require reconsideration as to how HIV drugs are being administered,
especially to children who are using these drugs, as myelin is still forming at a high rate in the early stages
of human development.

The paper was published this month in The Journal of Neuropathology and Experimental Neurology. Kelly
L. Jordan-Sciutto, professor and chair of Penn's School of Dental Medicine's Department of Pathology co-
led the research along with Judith B. Grinspan, who is a research scientist at CHOP and also a professor of
neurology at Penn's Perelman School of Medicine. Pharmaceutical companies have done an amazing job
developing drugs to make HIV patients live longer, but we're not done. The message we want to get out
there is that we want to make these patients' lives better while they are on ART,� says Jordan-Sciutto.

HIV Medications

In order to test whether ART really affects myelin production, the researchers tested the reaction of
oligodendrocytes against the drugs. They chose three drugs, which were once the most recommended
drug combination: protease inhibitors Ritonavir and Lopinavir, along with nucleoside reverse transcriptase
inhibitor Zidovudine (AZT). They found that Ritonavir and Lopinavir reduced the oligodendrocytes' ability
to mature and make myelin, whereas AZT had no effect. Removal of the drugs from the cells resulted in
reversal of the negative effects, allowing the cells to mature and produce myelin normally. They also
tested Ritonavir on adult mice, and after two weeks of treatment, it was found that the animals had
reduced levels of mature myelin in their frontal cortex.

Lastly, the team also examined human brain tissue from HIV-infected patients provided by another
collaborator, Benjamin B. Gelman, who is from the University of Texas Medical Branch. Comparison
between HIV-positive and HIV-negative individuals revealed that there was no significant difference
between myelin levels. However, comparing these two groups to HIV-positive individuals who were
experiencing cognitive defects showed that there was a reduction in the levels of myelin basic protein
(MBP) in those who were experiencing cognitive problems.

The researchers have yet to determine the mechanism as to why ARTs cause these problems in myelin
production. Understanding the effects of drugs on oligodendrocytes could also be actually helpful in other
diseases that are oligodendrocyte-function related, such as multiple sclerosis, which manifests by a
reduction of myelin in the brain.

High-fat diet causes the connections between neurons to be degraded

Jan 29, 2016

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Consuming a high-fat diet causes most living organisms to become obese, but apparently, another bad�effect of having a high-fat diet includes causing the normally busy immune cells in our brain to become�inactive and start eating up the connections between our neurons.

Fortunately, going on a low-fat diet for just two months apparently reverses the effect of having lowered
cognitive ability as weight begins to go back to normal, at least in mice.

Microglia eating synapses is contributing to synapse loss and cognitive impairment in obesity,� said Dr.
Alexis M. Stranahan, neuroscientist in the Department of Neuroscience and Regenerative Medicine at the
Medical College of Georgia, and the corresponding author of the study published in the journal Brain,
Behavior, and Immunity. On the one hand, that is very scary, but it's also reversible, meaning that if you
go back on a low-fat diet that does not even completely wipe out the adiposity, you can completely
reverse these cellular processes in the brain and maintain cognition.�

What happens is that when the body accumulates too much fat, the microglia in the brain initiate an
autoimmune response. Microglia have the same ability as macrophages, in which they are able to ingest
waste and other harmful materials in the brain, which supposedly supports the function and maintains
the health of neurons. However, when the mice get obese, the microglia seem to overeat.

High Fat Diet and Neurons

The study used male mice in which one group was given a diet that consisted of chow that had 10 percent
of the calories coming from saturated fat, while the other group had 60 percent. The researchers also
made sure that both chows were similar in other key ingredients. In human terms, it was like having a
healthy diet versus a fast-food diet.

At four, eight and twelve weeks, the scientists measured metabolic indicators, such as weight, food intake,
insulin and serum glucose levels. At the same time, they also measured the levels of proteins that
indicated the number of synapses in the hippocampus, which is the center of learning and memory.

At four weeks, levels in both groups of mice were the same. At eight weeks, everything was also pretty
much the same except for weight, in which mice who were on the high-fat diet were fatter. At twelve
weeks, the mice on a high-fat diet were obese, had elevated cytokine levels and had a reduced number
of synapse markers and function.

After twelve weeks, the researchers change half of the mice having the high-fat diet to a low-fat diet, and
it took around 2 months for their weight to go back to normal. On the other hand, those who were still
on a high-fat diet continued to get fat, getting more inflamed and lost more synapses. The microglial
structures called processes, which normally help in maintaining synaptic function, continued to weaken.
Similarly, dendritic spines on neurons which get input from synapses also withered with the high-fat diet.
However, converting to the low-fat diet both components of both cells were restored.

Obesity causes extreme overkill in microglial cells, which are usually sensitive and very crucial in
maintaining the health of neurons. This is very promising,� said Stanahan. The results that were seen in
the study could open new purposes for drugs used for conditions such as rheumatoid arthritis and Crohn's
disease, which block inflammatory cytokines, which are elevated in the brains of obese mice.

Father’s diet before child’s birth may influence offspring’s health

Jan 28, 2016

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Evidence is increasing that the parents' lifestyle even before they have children have an effect on the
health of their offspring. A study from the Novo Nordisk Foundation Center for Basic Metabolic
Research explains how.

In a study published in Cell Metabolism, Associate Professor Roman Barrès' and colleagues compared the
sperm cells between 13 lean men and 10 obese men. They were able to discover that in there were
different epigenetic marks in both that would affect their offspring's appetite.

However, obesity was not the only factor that the researchers discovered. After observing six men after a
year following gastric-bypass surgery, which is an effective way to lose weight, the researchers discovered
that there were around 4,000 structural changes in the sperm's DNA.

Barrès says that they still need to further examine as to what these differences mean. However, it is
important to note that this is already evidence that sperm also carries genetic information about a man's
weight. Thus, weight loss in fathers may more likely influence the eating behavior of their children.

Epidemiological observations revealed that acute nutritional stress, e.g. famine, in one generation can
increase the risk of developing diabetes in the following generations,� says Barrès.

Barrès also quoted a study that showed that the availability of food in a small Swedish village during a
time of famine is associated with the grandchildren having cardiometabolic diseases. The likely reason for
this is that the ancestors' gametes influenced the health of the grandchildren. Gametes carry epigenetic
marks, which change the structure of DNA once attached, thereby controlling the expression of genes.

The researchers proved that weight loss can change epigenetic information in male spermatozoa by
checking differences in small RNA expressions and DNA methylation patterns. This would obviously
consequently affect the development of the future embryo and the child's physiology. They were not
expecting to see such drastic changes in the epigenetics due to environmental pressure. Discovering that
lifestyle and environmental factors, such as a person's nutritional state, can shape the information in our
gametes and thereby modify the eating behavior of the next generation is, to my mind, an important find,�
says Barrès.

If these findings are viewed in the context of obesity, which is a worldwide heritable metabolic disorder
which is greatly affected by environmental factors such as diet and exercise, the fact that weight loss in
potential fathers has an effect on the eating behavior of their future children is quite groundbreaking.

Soetkin Verstehye, co-first author of the paper, says that the study increases awareness about the
importance of lifestyle, such as what we eat and if we do exercise, even prior to conception. The way we
eat and our level of physical activity before we conceive may be important to our future children's health
and development,� says Verstehye.

This field of research is still quite young, but the emergence of this study changes the assumption that our
gametes carry genetic information that cannot be changed. Human traits that were once thought to be�unchangeable could possibly be modifiable, in that what we do in our daily lives may actually affect not
only our personal health, but the health of our future generations as well.

Exercise enhances plasticity of the brain

Jan 27, 2016

2159

Processes in the brain such as learning, memory and repair are reliant on the ability of the neuronal�cells to change in time in tandem with experience.

A research paper published in the Cell Press journal�Current Biology reports that people who exercise may be able to improve this plasticity of the adult�brain.

The research mainly performed experiments on the visual cortex, and is seen as good news for people�with conditions that are related to this area of the brain, such as amblyopia or lazy eye, traumatic brain�injury, as well as many others.

Claudia Lunghi of the University of Pisa in Italy says that they provide the first demonstration that�moderate levels of physical activity enhance neuroplasticity in the visual cortex of adult humans.�

They were able to prove this by showing that moderate levels of physical activity can actually increase the�plasticity of the adult visual cortex. Their results imply that there will be a new opening in the development of non-invasive therapies that make use of the brain's plasticity.

Brain Plasticity and Exercise

The plasticity of the cerebral cortex is mainly at its maximum in the early stages of life, in which the�developing brain is still being molded by experience. However, as we age, this plasticity is thought to�decline. The decline that is generally seen is much more evident in the sensory portion of the brain.

Previous studies conducted by Lunghi's colleague Alessandro Sale, who is from the National Research
Council's Neuroscience Institute, showed that animals performing physical activity, such as rats that run
on a wheel, have higher levels of neuronal plasticity in the visual cortex, and also have improved recovery
from amblyopia when compared with sedentary animals.

In order to find out whether the same holds true for humans, Lunghi and colleagues measured the
plasticity of the adult visual cortex using a test that measures binocular rivalry. Usually, our eyes actually
are coordinated and work with each other. However, if one eye is covered with a patch for a long span of
time, the eye with the patch becomes stronger since the visual part of the brain attempts to compensate
because of the lack of visual input. The intensity of the imbalance that results is a sign of the brain's visual
plasticity, and presenting each eye with incompatible images allows us to measure this. They performed
this on 20 adults, doing this test twice: one in a deprivation test, in which the subjects with one eye
patched were watching a movie, and then again eye patched while exercising on a stationary bike for 10-
minute intervals while watching the movie.

One theory that the researchers have come up is that this effect results from a decrease in the inhibitory
neurotransmitter GABA while doing exercise. Regardless of the mechanism though, the results imply that
doing exercise is a very important activity in maintaining the brain's health and recovery.

According to Lunghi, the study suggests that doing physical activity, which is already generally beneficial
for the general health of a patient, could also be used to increase the efficiency of the treatment being
administered.

The researchers plan to investigate the effects of moderate levels of exercise on visual ability in amblyopic
adults and also to check what mechanisms are involved.

Detailed structure of key component in bacterial decision-making elucidated

Jan 26, 2016

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For the case of bacteria that swim, choosing whether to stay on the same direction or change course is�quite crucial for survival.

A new study published in the journal eLife reports atomic-level details of the�structure that allows swimming bacteria to detect their surroundings and determine when they have�to change direction.

The research, led by University of Illinois physics professor Klaus Schulten, opens a big door in trying to
understand how the bacterial brain� works.

On the surface of a bacterium are loads of receptors that detect its surroundings for it to determine what
the next step is. This is pretty much similar to the different senses that animals have and process in their
brains. Likewise, bacteria are single-celled organisms and consequently do not possess brains. Despite this,
they are still able to manage, organize and remember� the signals that they are able to pick up using
their receptors in such a way that allows them to survive.

The receptors that are found on the cell surface of bacteria can detect different types of things, including
light, chemicals, as well as edible and poisonous stuff, and upon detection, transmit the signals
downstream to proteins called kinases. Depending on the stimulus, the proteins simply give the end
decision of either continuing or changing direction.

If in any case, the decision to change direction is made, a kinase protein in turn activates another one,
called CheY (pronounced �key why'), which then detaches and then migrates to the flagella to activate
mechanisms that cause the flagella to spin in reverse.

Chemosensory Array

Previous studies have produced bits and pieces of the structure of this molecular machine which is
responsible for this process, which is called the chemosensory array. However, these studies were not
able to give a clear resolution of its molecular structure.

Peijun Zhang, who is the co-author of the study, and is from the University of Pittsburgh, helped by
devising a technique that was able to purify the proteins that are involved in the array, which he then put
together in such a way that they formed thin layers just enough to allow them to take clear 3-D images
using electron microscopy. This technique was able to greatly increase the resolution of the data. The
picture was then processed using molecular dynamic flexible fitting, which is a computer modeling
technique being used at Schulten's lab.

This study showed the key interactions that occur among the proteins that are involved in the
chemosensory array. One example is for the case of CheA, in which it changes its orientation with respect
to the other proteins, in a motion to which the researchers named dipping�. Further experiments showed
that this is very essential to a bacterium's response to its environment.

One significant question that is still unanswered is how the signal is being passed from the receptors to
the kinases. It has to be a motion. It can't be anything else. But what kind of motion?�, says Schulten.

Certainly more research is needed to determine the relationships between the components of the system,
as well as the mechanism involved. However, the study surely denotes a huge jump in understanding how
the system works.

Correlation Between Semen Exposure and HIV Resistance Found

Jan 25, 2016

2180

Around have of those infected by HIV around the world are women.

Commercial sex workers, who are�seen to have a higher risk of getting the virus, have been studied for a long time in order to find ways�of decreasing the number of HIV infections. There are some areas in the world where, even though�there is a high prevalence of HIV, continued sexual activity, and less condom use, some of the female
sex workers are still devoid of the virus. However, the reason as to why these women have continued�resistance to HIV is still not known, as these women do not show any of the known immune responses�against HIV.

In a study published in the journal Mucosal Immunology by researchers from The Wistar Institute, data
revealed that the continued exposure of sex workers to semen causes changes in the microenvironment
of the cervix and vagina in such a way that HIV resistance is increased. This data may be used in the future
to develop strategies to prevent the transmission of HIV.

Luis J. Montaner, DVM, DPhil, who is the Herbert Kean, MD Family Professor at the Wistar Institute and
the lead author of the study, says that creating the link between sex work, changes in the immune system
and semen exposure gives us a good look as to whether the continued exposure to semen and its effect
on the female reproductive tract actually contributes to HIV resistance and is the reason why some sex
workers are still uninfected even if they don't use condoms. It also clearly indicates that women are
equipped to activate mechanisms of resistance due to sex itself, which we did not expect to find at the
start of this research,� he adds.

HIV Resistance

The study was in collaboration with researchers from the University of Puerto Rico Maternal Infant Studies
Center and analyzed a set of female sex workers in San Juan who were not infected with the virus,
comparing them to women who had self-reported low semen exposure in the same area. The median age
was 35.50 years old, and most were working in the industry for a minimum of three years. Both groups
were also compared on the basis of unprotected sex, whether or not they used contraceptives and what
types the used. Sex workers who had other infections such as syphilis or chlamydia were excluded from
the study.

Three mechanisms were formulated by the researchers that may explain the resistance of the sex workers
to HIV. The first one was the observed lower rates of immune activation in the blood and mucosal tissue
of these women. This is very important, as HIV needs an active immune system to thrive and reproduce.
Second, these women had high levels of interferon e, which is a signaling protein that serves to protect
the female reproductive tract from bacterial and viral infections. Lastly, factors such as CD4 and
Nucleoporin 153, which are critical for HIV to survive, had low expression levels.

Carmen D. Zorrilla, MD, professor of obstetrics and gynecology at the University of Puerto Rico, who is
also one of the authors of the study, states that this work could provide insight into why cohorts of
women at risk recruited for preventive trials in the United States have demonstrated lower sero-
conversion rates than expected on community prevalence.�

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