Welcome to The Visible Embryo

 

 

Home-- -History-- -Bibliography- -Pregnancy Timeline- --Prescription Drugs in Pregnancy- -- Pregnancy Calculator- --Female Reproductive System- -Contact
 

Welcome to The Visible Embryo, a comprehensive educational resource on human development from conception to birth.

The Visible Embryo provides visual references for changes in fetal development throughout pregnancy and can be navigated via fetal development or maternal changes.

The National Institutes of Child Health and Human Development awarded Phase I and Phase II Small Business Innovative Research Grants to develop The Visible Embryo. Initally designed to evaluate the internet as a teaching tool for first year medical students, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than one million visitors each month.

Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

WHO International Clinical Trials Registry Platform


The World Health Organization (WHO) has created a new Web site to help researchers, doctors and
patients obtain reliable information on high-quality clinical trials. Now you can go to one website and search all registers to identify clinical trial research underway around the world!



Home

History

Bibliography

Pregnancy Timeline

Prescription Drug Effects on Pregnancy

Pregnancy Calculator

Female Reproductive System

Contact The Visible Embryo

News Alerts Archive

Disclaimer: The Visible Embryo web site is provided for your general information only. The information contained on this site should not be treated as a substitute for medical, legal or other professional advice. Neither is The Visible Embryo responsible or liable for the contents of any websites of third parties which are listed on this site.
Content protected under a Creative Commons License.

No dirivative works may be made or used for commercial purposes.

 

Pregnancy Timeline by SemestersFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
CLICK ON weeks 0 - 40 and follow along every 2 weeks of fetal development
Google Search artcles published since 2007
 
 

Home | Pregnancy Timeline | News Alerts |News Archive Oct 23, 2013

 

Electron microscope image of TNC.







WHO Child Growth Charts

 

 

 

Breast milk key to protecting babies from HIV?

A substance in breast milk that neutralizes HIV and may protect babies from acquiring HIV from their infected mothers has been identified for the first time by researchers at Duke Medicine.

The protein, called Tenascin-C or TNC, had previously been recognized as playing a role in wound healing, but had not been known to have antimicrobial properties. The discovery could lead to potential new HIV-prevention strategies.

Reporting in the journal Proceedings of the National Academy of Sciences during the week of Oct. 21, 2013, the researchers describe how the TNC protein in breast milk binds to and neutralizes the HIV virus, potentially protecting exposed infants who might otherwise become infected from repeated exposures to the virus.

"Even though we have antiretroviral drugs that can work to prevent mother-to-child transmission, not every pregnant woman is being tested for HIV, and less than 60 percent are receiving the prevention drugs, particularly in countries with few resources," said senior author Sallie Permar, M.D., Ph.D., assistant professor of pediatrics, immunology and molecular genetics and microbiology at Duke. "So there is still a need for alternative strategies to prevent mother-to-child transmission, which is why this work is important."


Worldwide in 2011, an estimated 330,000 children acquired HIV from their mothers during pregnancy or birth, or through breastfeeding according to UNICEF.


As international health organizations have set a goal of eliminating mother-to-child infections, researchers have worked to develop safe and affordable alternatives to antiretroviral therapy that can be used to block HIV transmission to infants.

Permar and colleagues focused on breast milk, which has long been recognized as having some protective quality that inhibits mother-to-child transmission despite multiple daily exposures over months and even years of nursing. Earlier studies had identified some antiviral properties in breast milk, but the majority of the HIV-neutralizing activity of breast milk remained unexplained. More recent studies pointed to a large protein that had yet to be identified.

In their study, the Duke team screened mature milk samples from uninfected women for neutralizing activity against a panel of HIV strains, confirming that all of the detectable HIV-neutralization activity was contained in the high molecular weight portion. Using a multi-step protein separation process, the researchers narrowed the detectable HIV-neutralization activity to a single protein, and identified it as TNC.

"TNC is a component of the extracellular matrix that is integral to how tissues hold themselves together," Permar said, noting that co-author Harold Erickson, Ph.D., professor of cell biology at Duke, was among the first to identify and describe TNC in the 1980s. "This is a protein involved during wound healing, playing a role in tissue repair. It is also known to be important in fetal development, but its reason for being a component of breast milk or its antiviral properties had never been described."


Further analysis described how TNC works against HIV by blocking virus entry. The protein is uniquely effective in capturing virus particles and neutralizes the virus, specifically binding to the HIV envelope. These properties provide widespread protection against infection.

"It's likely that TNC is acting in concert with other anti-HIV factors in breast milk, and further research should explore this. But given TNC's broad-spectrum HIV-1-binding and neutralizing activity, it could be developed as an HIV-prevention therapy, given orally to infants prior to breastfeeding, similar to the way oral rehydration salts are routinely administered to infants in developing regions."

Sallie Permar, M.D., Ph.D., assistant professor of pediatrics, immunology and molecular genetics and microbiology, Duke University.


Permar said TNC would also appear to be inherently safe, since it is a naturally occurring component of breast milk, and it may avoid the problem of HIV resistance to antiretroviral regimens that complicate maternal/infant applications.

"The discovery of the HIV inhibiting effect of this common protein in breast milk provides a potential explanation for why nursing infants born to HIV-infected mothers do not become infected more often than they do," said Barton F. Haynes, M.D., director of the Duke Human Vaccine Institute. "It also provides support for inducing inhibitory factors in breast milk that might be even more protective, such as antibodies, that would completely protect babies from HIV infection in this setting."

Significance
Achieving an AIDS-free generation will require elimination of breast milk transmission of HIV-1, as breastfeeding is a cornerstone of infant survival in developing regions. Antiretroviral prophylaxis considerably reduces postnatal HIV-1 transmission, yet its efficacy is limited by access, adherence, toxicities, and resistance of maternal HIV-1 strains. Alternative, safe strategies of impeding postnatal HIV-1 transmission will be required to eliminate infant HIV-1 infection. In this paper, we identify an innate HIV-neutralizing protein in breast milk, Tenascin-C, which captures and neutralizes HIV-1 virions via binding to the chemokine coreceptor binding site on the HIV-1 Envelope. This protein has the potential to be developed as a prevention strategy for postnatal and other modes of HIV-1 transmission.

Abstract
Achieving an AIDS-free generation will require elimination of postnatal transmission of HIV-1 while maintaining the nutritional and immunologic benefits of breastfeeding for infants in developing regions. Maternal/infant antiretroviral prophylaxis can reduce postnatal HIV-1 transmission, yet toxicities and the development of drug-resistant viral strains may limit the effectiveness of this strategy. Interestingly, in the absence of antiretroviral prophylaxis, greater than 90% of infants exposed to HIV-1 via breastfeeding remain uninfected, despite daily mucosal exposure to the virus for up to 2 y. Moreover, milk of uninfected women inherently neutralizes HIV-1 and prevents virus transmission in animal models, yet the factor(s) responsible for this anti-HIV activity is not well-defined. In this report, we identify a primary HIV-1–neutralizing protein in breast milk, Tenascin-C (TNC). TNC is an extracellular matrix protein important in fetal development and wound healing, yet its antimicrobial properties have not previously been established. Purified TNC captured and neutralized multiclade chronic and transmitted/founder HIV-1 variants, and depletion of TNC abolished the HIV-1–neutralizing activity of milk. TNC bound the HIV-1 Envelope protein at a site that is induced upon engagement of its primary receptor, CD4, and is blocked by V3 loop- (19B and F39F) and chemokine coreceptor binding site-directed (17B) monoclonal antibodies. Our results demonstrate the ability of an innate mucosal host protein found in milk to neutralize HIV-1 via binding to the chemokine coreceptor site, potentially explaining why the majority of HIV-1–exposed breastfed infants are protected against mucosal HIV-1 transmission.

In addition to Permar, co-senior author was S. Munir Alam. Other authors include Genevieve G. Fouda, Frederick H. Jaeger, Joshua D. Amos, Carrie Ho, Erika L. Kunz, Kara Anasti, Lisa W. Stamper, Brooke E. Liebl; Kimberly H. Barbas, Tomoo Ohashi, M. Arthur Moseley, Hua-Xin Liao and Harold P. Erickson.

The study was funded by the Doris Duke Charitable Foundation Clinical Scientist Development Award; Duke University School of Medicine; Center for HIV/AIDS Vaccine Immunology; and the National Institute of Allergic and Immunologic Diseases (U19 AI067854) (K08AI087992) (CA047056).

Original press releas:http://www.eurekalert.org/pub_releases/2013-10/embl-co101113.php