Daily Archives: April 23, 2014

Puberty: The New Normal


Neha Kamat’s presentation on menopause was very interesting to me! It really got me thinking about what factors may affect the age of onset for puberty. Studies have shown that girls around the world seem to be entering puberty a lot sooner. In the 1990’s African American girls were developing breasts at age 9 and Caucasian girls were developing breast at around 9.5 years old. Today, girls are entering puberty about 4 months earlier than in 1997. So what could be the cause? There are many hypotheses in the science community about why this is happening.

A very popular hypothesis, that does not constitute a lot of solid evidence, is that there are an increased amount of hormones in the food we eat. Meat and dairy are thought to be the main food groups with a high rate of hormones.  The hormone BPA in plastic food packaging has also been labeled as a culprit.

The well rounded obesity hypothesis has the most supporting evidence. There is a link between percentage of body fat and the onset age of puberty. A higher rate of body fat is believed to produce more estrogen, causing a faster onset of puberty. There have also been studies that suggest there is a noticeable difference in the age of puberty and ethnicity. African Americans and Hispanic girls tend to start puberty before Caucasian females. Although,  change in the onset of puberty has been recorded in most ethnicity’s, including Caucasians.

One thing this class has taught me is that changes in genotype/phenotype are usually do to a combination of factors! Puberty is not an exception to the rule.  The main culprit is probably many changes in the local environment. These environmental factors range from economics to climate conditions. There is even evidence that the prenatal environment may have effects on the onset of puberty! It is hard to narrow down exactly what could be the main cause of this pattern.

Other researchers suggest that people are not properly diagnosing the onset of puberty, “The appearance of acne and pubic hair is common even in infants and toddlers. It goes away. We need to be careful about how we identify the true onset of puberty”, warns Dr. Lawrence Silverman. Recently, boys have also been starting puberty earlier than usual. Not much research has been done because it is harder to pinpoint the onset of puberty in boys. Girls have clearly physical responses to puberty such as breast budding and menarche.

This is a topic that is worthwhile to research because studies show that girls who enter puberty earlier in life have higher rates of breast and uterine cancer. Data provided from this research may provide answers to a lot of questions around risk factors for cancer. Early development in girls has also been linked with poor self-esteem, eating disorders, and depression, as well as cigarette and alcohol use and earlier sexual activity.

The reason why girls of certain ethnicities are more susceptible to this change still remains a question today.





Dr. Mina Class Assignment

Dr. Minas presentation was really interesting to me. I just wanted to share my response to the assignment for that class period. I would love to hear feedback on whether or not you agree with me!

1.   I would like the students to read the nature draft paper (if anyone wants the     supplementary model stuff they can email me) and write down a few comments for why this paper should and should not be published in very high profile journal like Nature – as though they are reviewing the paper for publication. Note that this is instead of your normal synopsis – so bring a printed copy of this to turn in.

I really liked how under each results section the authors clearly identified why they were doing that test. Most papers simply state how the results support or refute the hypothesis. There is no mention as to why, initially, the experimenters decided to do that specific test in the first place. I prefer this layout because it made the results easier to follow. The figures were very helpful; specifically Figure 2. It really helped with visualization and it was not confusing. Many papers that we have read for this class had very complicated figures/tables that were hard to follow. The one thing that I think could be changed, in regards to the structure of the paper, is the order of the sections. I found it odd that the materials and methods sections came last. Personally, I prefer for the materials and methods section to come earlier in the paper. The take-away message of this paper is that flu vaccines do seem to cause higher rates of bacterial infections, but this negative effect does not outweigh the positive that vaccines do for the public.

2. Read the two news articles regarding the mBio paper and compare and contrast them.

The Greenmed info paper used the data from the paper to support anti-vaccine campaigns.  I do not feel this was the original intention of the paper. It was very biased. The authors used evidence from the paper to totally persuade people to not get vaccinated. The science now article stated the evidence from the paper, but it did not force an opinion on the public. It presents the evidence in a way that the public can use to come to an informed decision about vaccinations.  I also like how this article mentions Mina’s future research that could support or refute his original hypothesis. The first article did not credit the fact that this data is not collected in humans as of yet.

3.   I would also like them to consider the research as though they are the director of the CDC:

  • Is this research worth doing
  • Is it the CDC’s responsibility to report the results
  • What are the tradeoff’s that would ultimately be made and possible downstream effects of the CDC reporting these results, vs. the private sector.

 I do think that this research is worth doing. The public should be fully informed of the risks so that they can come to their own educated decision.  I do think that the private sector of healthcare might get backlash. Many people may start to oppose vaccinations, but that is not up to other to decide. Everyone is entitled to their own opinion. Also, if Mina’s suggestions about higher rates of infections due to lower vaccination rates does hold true, the implications could be worse than expected if many people decide against vaccinations. It is the CDC’s duty to report this information to the public. Immunizations are the major weapon of public health so is only fair that all the information is available to the public.

The link between Vaccines and Polio Eradication in India!

Dr. Mina was a guest lecturer to our class soon after India announced the eradication of polio! Many interesting questions came up in discussion that class period. The question that interested me the most was, ” What impacts will this data have on the anti-vaccination campaign?” . I think we can all agree that individuals against vaccination will definitely use Dr. Mina’s research to support their claims.

I think an important part of acquiring data like this is to make sure that the public is properly educated. I think that the greenmed article we read for class improperly relayed the data to the public. The data was used out of context in order to strengthen a personal argument. This is one reason why I do not agree with the CDC’s decision to no longer support Dr. Mina’s research. The CDC, as a highly respected health organization, has a duty to properly educate the public about new information regarding vaccines. After that, it is the personal opinion of the individual to take a stance in regard to vaccines.

In this blog post I just wanted to provide some information on how polio eradication was achieved in India. Vaccinations were a huge part in this achievement:

Polio is a highly contagious virus that affects the nervous system (WHO). The virus is spread through contaminated water which is pretty abundant in impoverished areas of India. Polio has been a challenge to eradicate in India because of many reasons such as a high population density, poor sanitation, and low rates of routine immunizations (Gates Foundation).  India has been well on its way to the eradication of polio for some time now. A small child, Rukhsar Khatoon, was India’s last reported polio case in January of 2011 (CNN Health). The surveillance of polio proved to be a very important step in India’s eradication process (WHO). The surveillance strategy helped to pin point which populations had a greater risk of polio (WHO). The National Polio Surveillance Project was started in 1997 (WHO). They started by supporting early detection as well as testing stool samples of children who had recently become paralyzed (WHO). Later, environmental surveillance proved to be one of the missing links in the surveillance system (WHO).

Immunization efforts were also a big part of India’s success story! Innovative ideas on how to keep the polio vaccine refrigerated were a major part in the success of immunization (CNN health). There are many parts of India without electricity which presented a major issue in attempting to vaccinate rural villages (CNN health). The solution to this problem was refrigerators powered by kerosene (CNN health). Another major issue with vaccination in India was the lack of trust people had in the polio vaccine. Many people believed that the polio vaccine was a government conspiracy that presented adverse side effects, this lead people to refuse polio vaccination (CNN health). Infertility and even death were some of the rumored side effects of the vaccine. Prominent religious figures and government officials played a major role in gaining the trust of the public to try the vaccine (CNN health). This is a great example of how respected individuals/organizations have a huge influence of the opinions of people.The eradication of polio in India required stead fast dedication from all parties involved.







The Human Microbiome May Be Seeded Before Birth

This NYTimes article is relevant to the nature of our discussion on microbiomes and how they can be used for the treatment of various disorders. The article begins by addressing the common misconceptions that fetuses are sterile and that babies are first exposed to bacteria when they exit the birth canal. In 2010, Dr. Josef Neu closely studied stool samples from newborns before their first meal and found diverse microbes in the samples, regardless of whether the child was born on time or prematurely. Additionally, Dr. Esther Quintana studied the amniotic fluid, placenta, and umbilical cord blood of healthy babies and found that each contained a certain amount of bacteria. Questions remain, however, on how the bacteria are first transported from the mother to the fetus and whether a random or beneficial set of microbes are delivered to the fetus during pregnancy. Currently, Dr. Neu and other researchers are studying whether a microbiome helps a fetus during pregnancy. Intriguingly, beyond exploring the microbiome found in fetuses, researchers are also closely studying how the microbiome can be functionalized to treat disorders such as gut infections and autoimmune disorders. For example, the article mentions the possibility of providing a mother with a ‘microbial cocktail’ that can be used to transport specific microbes to the fetus for the treatment of a specific disorder.

I found this article rather interesting as I was not aware that bacteria naturally occur in fetuses, amniotic fluid, and placenta blood. Building from our discussion in class, this article is evolutionarily significant as it suggests that a mother can possibly influence her child’s microbiome, which can ultimately have extensive health and dietary impacts for the child.


Human Behavior and the Evolution of Sexually Transmitted Diseases (Synopsis)

Human behavior is closely related to the evolution of sexually transmitted infections, and this paper talks about the impact of the determinants of the STI on disease prevalence and transmission. The paper lists numerous factors that influence infectious disease emergence, including ecological change, human demographics and behavior, international travel and commerce, technology and industry, and microbial adaptation and change. Usually, the combinations of multiple factors that are happening simultaneously affect the transmission of the disease. In addition, the review states that the most direct influence on the evolution of sexually transmitted infections is sexuality and sexual behavior. In order to establish how infectious disease is spread, evaluation of individual sexual behaviors, types of exposure, and the impact of economic, social and structural factor is required. The large variation in age structure in a population has been recognized as crucial factor in the spread of STIs.

Although the determinants of STI prevalence such as urbanization, migration, and poverty were around for a long time, the relatively recent industrialization caused greater economic inequality and changing migration patterns that facilitated the spread of STIs into new populations. The norms may also influence the spread of STIs and size of the population susceptible to STIs. The paper also states that public health and medicine have both positive and negative effects on STI control. Behavioral interventions such as giving sex education, prevention of disease progression, and giving vaccines against HPV strains have been developed to give positive effects. In contrast, the introduction of oral contraceptives and Viagra has increased sexual risk behavior.

In conclusion, the writer emphasizes that human developments affect the spread of sexually transmitted disease agent and its pathogenesis. For example, economic and gender inequality, increased mobility, and global variability of sexual behavior affect the evolution of the agents by changing age structures, unequal gender rates, and globalization.


Citation: Nahmias, S. B. and Nahmias, D. (2011), Society, sex, and STIs: human behavior and the evolution of sexually transmitted diseases and their agents. Annals of the New York Academy of Sciences, 1230: 59–73. doi: 10.1111/j.1749-6632.2011.06079.x

The Role of Human Movement in the Transmission of Vector-Borne Disease

Human movement in terms of spatial and temporal scales is an important factor that affects many vector-borne disease by influencing exposure to vectors and transmission of pathogens. However, very little is known about individual human movement patterns and its effects on the dynamics of vector-borne pathogens. Studying and understanding the human movement and its influences on disease dynamics will enable scientists to come up with a better intervention and disease prevention. The study examines the role and the importance of human movement for pathogen transmission by mostly focusing on mosquito-borne virus. According to the paper, exposure that is due to human movement strongly influences the transmission dynamics of pathogens. For instance, the national or international individual movement drives pathogen introduction and reintroduction.

In order to study the dengue, the ‘activity space’ model was used to determine the few locations individuals visit and spend most of their time. By incorporating the knowledge of vector behavior and the outcome of the activity space model, scientists were able to identify places and individuals that contribute disproportionately to pathogen transmission dynamics. An interesting outcome that the activity space model presented was that the movements of pathogen transmission typically occur mostly at night when hosts are inactive. The paper emphasizes that a better understanding of the role of human movement on pathogen transmission is critical in predicting possible disease outbreak and coming up with better disease preventions schemes.

Citation: Stoddard ST, Morrison AC, Vazquez-Prokopec GM, PAZ Soldan V, KOchel TJ, et al. (2009) The Role of Human Movement in the Transmission of Vector-borne pathogens. PLoS Negl Trop Dis 3(7): e481. doi:10.1371/journal.pntd.0000481