Author Archives: mblnkns1

Feb
12
2013

New Research in Embryogenesis of the Human Eye

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The individual components of the eye work in unison, with each part playing a vital role in providing clear vision.  The cornea acts as the eye’s main focusing segment.  It takes a widely diverging ray of light and bends it through the pupil which is surrounded by the colored iris.  The eye is very complex, and with this complexity various problems can occur.  With new technology, doctors are able to restore many forms of impaired vision.

A new study completed in Kobe, Japan looked into the development of mammalian eyes from stem cells.  Yoshiki Sasai grew what is now known as an optic cup using human stem cells.  This breakthrough was encouraging due to the ability for Sasai to grow three-dimensional tissues unlike the two-deminsional sheets that were being developed.  Observing the optic cup, structural similarities were seen when compared to normal development of an human in vitro eye.  Sasai was impressed to notice that layers of the eye were grown in the same sequence without his aid.

This new achievement could aid scientists in a clinical setting aiding to the increased successes in transplanting stem cell photoreceptors into mice.  This transplant only offered rod receptors that would only give unclear images.  Sasai’s optic cup is being looked at to one day integrate both photoreceptor tissues into humans.

Yoshiki, Sasai, Eiraku Mototsugu, et al. “Self-organizing optic-cup morphogenesis in three-dimensional culture.” Nature. 472.7341 (2010): 51-56. Web. 28 Jan. 2013. <10.1038/nature09941 >.

Tortora, Gerard J., and Bryan Derrickson. Principles of Anatomy and Physiology. Hoboken, NJ: John Wiley & Sons, 2010. Print.

Dec
04
2012

Nervous System with NO Synapse

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Neurons are the fundamental cell of the nervous system which directs responses to stimuli, coordinates activities of other organ systems, and interprets sensory information about external conditions (Tortora and Derrickson 2012).  These neurons send information from neuron to neuron through synapses by electrical or chemical signals.  Scientists are studying how neurons do not need to synapse with other neurons to be able to send and receive information.   Neuron communications are being observed to take place without any direct connections to other neurons.

Jean-Pierre Rospars was the first to observe what is called ephaptic interactions in flies, which occurs when a neuron silences a neighboring neuron instead of sending the signal though the nervous system.  Studies by Chih Ying-Su, on Drosophila melanogaster were completed by a test on two neurons (ab3A and ab3B) which control for methyl hexanoate and 2-heptanone, respectively.  After being exposed to each of the chemicals individually, the exposed neuron would spike while the other neuron would be shut down.  This is the example of ephaptic interactions Su was looking to expose.

Su also tested these interactions by introducing synaptic blocking chemicals to Drosophila melanogaster.  The test was completed between two neurons that dealt with the flies attraction to apple cider vinegar and the distaste for carbon dioxide.  After blocking the synapses for vinegar, the flies were placed in front of two arms which both contained carbon dioxide, but only one arm also enclosed vinegar.  The flies followed down the arm with the added vinegar which gave Su a conclusion that flies were using fluid inside of the sensillum to create an electric field when the neuron was being blocked.

The phenomenon known as emphatic coupling has been discussed for a long time but it has been perceived as obscure.  A factor in the arcane observations has been the lack of evidence on the subject.  Further studies, along with the study completed by Su, show that knowledge of this occurrence might be useful for protecting crops from hungry insects, or people from disease-carrying insects.

 

Sources:

Tortora G.J. and B. Derrickson. 2012. Principles of Anatomy and Physiology. 13th ed., John Wiley and Sons

Su, Chih-Ying; Menuz, Karen; Reisert, Johannes; Carlson, John R. “Non-synaptic inhibition between grouped neurons in an olfactory circuit.” Nature. 21 Nov. 2012. <http://www.nature.com /nature/journa/vaop/ncurrent/full/nature11712.html?WT.ec_id=NATURE-20121122

Nov
20
2012

Teenage Brain

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The human brain is a vastly complex organ consisting of billions of interconnected neurons that are making different connections every day; this gives evidence that the brain is one of the most important parts of the body.  Studying the brain as it grows is crucial, especially the adolescent brain as it develops from childhood to adulthood.  Research is now looking at the teenage brain as it grows and functions cognitively and structurally.

ScienceNews reviewed an article looking at how crucial brain development is during teen years and how “pushing the limits” in daredevil behaviors are a necessary phase.  Eveline Crone is studying brain development using MRI scans seeing how teen brains react when playing computer games.  The high risks and rewards of casino games were seen to stimulate more brain activity in teens than children or adults.  High amounts of dopamine were seen and increased activity in the ventral striatum which acts in reward-based decision making.  A study completed in 2007 showed that the activity from the ventral striatum changes over time in development of the brain and is influenced more in teenage years resulting in higher risk behaviors than in adulthood.

Understanding how the brain works is crucial in comprehending how a certain behavior begins and continues through a person’s life.  More studies need to be completed so certain behavioral patterns can be predicted from MRI scans early in life and can inhibit specific ones and encourage other parts to development more adequately.

References:

“Role of ventral striatum in reward-based decision making.” National Center for Biotechnology Information. U.S. National Library of Medicine, 02 July 2007. Web. 08 Nov. 2012. <http://www.ncbi.nlm.nih.gov/pubmed?term=Role[Title] AND ventral[Title] AND striatum[Title] AND reward-based[Title] AND decision[Title] AND making[Title]>.

“The Teenage Brain.” Science News. N.p., 17 Oct. 2012. Web. 08 Nov. 2012. <http://www.sciencenews.org/2012/10/the-teenage-brain/>.

Sep
12
2012

In Virto Fertilization (IVF)

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After being tested in veterinary practices in the early 19th century, in vitro fertilization (IVF) has been used in hospitals and clinics for over thirty years, since the first successful test tube baby was born in 1978.  Being an in vitro child, these articles are a high priority to me.  These articles looked at problems regarding fertilization and development of in vitro children through cell and mitosis development.

A study completed by Schieve et al. (2004) stated that pregnancies conceived through assisted reproductive technology (ART) have a high perinatal complication rate.  Twin and higher order of multiple gestations are at increased risk for per-term delivery compared with singletons.  Researchers say the most common method to reduce the premature birth risk when using IVF is to avoid multiple births.  Also, multiple births are at higher risk of mortality when using in vitro fertilization.

With research and IVF, adults need to be reassured that this method of conception will not endanger their children’s health and vitality after birth.  Understanding the genetics of IVF and the possible complications can keep a parent from the risk of their child having a disability.

 

L. A. Schieve, H. B. Peterson, S. F. Meikle, G. Jeng, I. Danel, N. M. Burnett, L. S. Wilcox. Live-birth rates and multiple-birth risk using in vitro fertilization.JAMA. 1999 November 17; 282(19): 1832–1838.

Tarkan, Laurie. “Lowering the Odds Of Multiple Births.” The New York Times. The New York Times, 19  Feb. 2008. Web. 06 Sept. 2012. <http://www.nytimes.com/2008/02/19/health/19mult.html?pagewanted=all>.