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Biomedical subjects

C E Simpson

Publications and source records attributed to C E Simpson.

9 recordsLinked to original sources
PubMed2005

Acetylecholinesterase-based biosensor electrodes for organophosphate pesticide detection. II. Immobilization and stabilization of acetylecholinesterase.

The dry and wet stability of Drosophila acetylcholinesterase non-covalently immobilized onto polyethyleneimine modified screen-printed carbon electrodes was improved when compared to non-immobilized acetylcholinesterase, and acetylcholinesterase covalently immobilized onto dialdehyde and polyethyleneimine modified electrodes. Stabilizer mixtures were characterized for additional stabilization of acetylcholinesterase during storage in the dry state, with dextran-sulphate/sucrose and polygalacturonic acid/sucrose mixtures proving highly effective for long-term storage of biosensor electrodes.

Acetylcholinesterase↗
PubMed2004

Acetylcholinesterase-based biosensor electrodes for organophosphate pesticide detection. I. Modification of carbon surface for immobilization of acetylcholinesterase.

Screen-printed carbon electrodes modified with the dialdehydes, glutaraldehyde and terephthaldicarboxaldehyde, and then polyethyleneimine have been utilized for production of pesticide biosensors based on acetylcholinesterase. To improve the extent of dialdehyde modification, the electrodes were NH2-derivatized, initially by electrochemical reduction of 4-nitrobenzenediazonium to a nitroaryl radical permitting attachment to the carbon surface. Subsequent reduction of the 4-nitrobenzene yields a 4-aminobenzene modified carbon surface. Drosophila melanogaster acetylcholinesterase was immobilized either covalently onto dialdehyde modified electrodes or non-covalently onto polyethyleneimine modified electrodes. Internal diffusion limitations due to the dialdehyde and polyethyleneimine modifications increased the apparent Km of the immobilized enzyme. The thiocholine sensitivity was about 90% for dialdehyde modified electrodes and about 10% for polyethyleneimine modified electrodes as compared with non-modified carbon electrodes. The detection limit of the biosensors produced by non-covalent immobilization of acetylcholinesterase onto polyethyleneimine modified carbon electrodes was found to be about 10(-10) M for the organophosphate pesticide dichlorvos.

Acetylcholinesterase↗
PubMed2001

Transmission genetics of chromatin from a synthetic amphidiploid to cultivated peanut (Arachis hypogaea L.). broadening the gene pool of a monophyletic polyploid species.

Polyploidy creates severe genetic bottlenecks, contributing to the genetic vulnerability of leading crops. Cultivated peanut is thought to be of monophyletic origin, harboring relatively little genetic diversity. To introduce variability from diploid wild species into tetraploid cultivated Arachis hypogaea, a synthetic amphidiploid [[A. batizocoi K9484 x (A. cardenasii GKP10017 x A. diogoi GKP10602)](4x)] was used as donor parent to generate a backcross population of 78 progeny. Three hundred seventy RFLP loci were mapped onto 23 linkage groups, spanning 2210 cM. Chromatin derived from the two A-genome diploid ancestors (A. cardenasii and A. diogoi) comprised mosaic chromosomes, reflecting crossing over in the diploid A-genome interspecific F(1) hybrid. Recombination between chromosomes in the tetraploid progeny was similar to chromosome pairing reported for A. hypogaea, with recombination generally between chromosomes of the same subgenomic affinity. Segregation distortion was observed for 25% of the markers, distributed over 20 linkage groups. Unexpectedly, 68% of the markers deviating from expected segregation showed an excess of the synthetic parent allele. Genetic consequences, relationship to species origins, and significance for comparative genetics are discussed.

Arachis↗
PubMed1991

The current and future need for minority medical faculty.

Little progress has been made in increasing the number of minority faculty members at US medical schools. From 1975 through 1989, underrepresented minority medical faculty increased only 0.3%--from 2.7% to 3.0%. In the field of medicine in general, only 3% of physicians are African-American and 3% are Hispanic, while the African-American and Hispanic populations are approximately 12% and 7%, respectively, of the total US population. A number of factors have caused the persistent underrepresentation of minority health professions trainees: inadequate or inappropriate career counseling, admissions policies, relatively high attrition rates after matriculation, substantial costs of education, and lack of appropriate mentors and role models. Helping minority students overcome these obstacles requires providing them with appropriate information, preparation, motivation, and opportunities at all stages of the educational process. Attention must focus on recruiting minority students into the scientific, academic professions if an increase is to occur in numbers of underrepresented minorities in all specialties of medicine. The Health Resources and Services Administration and private foundations have committed to providing funds to educational institutions to help encourage minority students to pursue academic careers. Leadership at these institutions must also commit to increasing the numbers of underrepresented minority faculty and senior administrators.

Ethnicity↗
PubMedDate not supplied

Factors affecting the supply of minority physicians in 2000.

There was a substantial increase in the number of black and Hispanic physicians between 1970 and 1985. During the next 15 years, 1985 to 2000, the increase is projected to continue. The factors that will determine the size of the increase and the changes in physician to population ratios include black and Hispanic population increases, medical school costs, availability of student support, minority enrollment in undergraduate schools and the pool of these students who will be applicants to medical school, attrition during medical school, competition from other professions for talented minority students, and the effects of intervention programs such as the Health Careers Opportunity Program. The most likely outcome would seem to be that the increases in black and Hispanic physicians will continue to 2000 at 1985 levels because the data show neither strong positive nor strong negative net influences for the factors examined.

Black or African American↗
PubMedDate not supplied

Increasing the pool of qualified minority medical school applicants: premedical training at historically black colleges and universities.

Historically black colleges and universities have educated significant numbers of black students preparing for careers in medicine. These institutions have the potential to make even greater contributions to the pool of black medical school applicants and ultimately to the supply of black physicians. The Division of Disadvantaged Assistance, Bureau of Health Professions, Health Resources and Services Administration within the Public Health Service, commissioned a study of the curriculums and other factors related to premedical education. The study was conducted at the historically black colleges and universities that graduate a large number of students who gain admission to medical school, and the historically black colleges and universities whose students are less successful in gaining admission to medical school. Nine historically black colleges and universities participated in a self-assessment of their undergraduate premedical curriculums. The findings from schools with higher acceptance rates were compared with those of schools with lower acceptance rates to identify factors contributing to the production of significant numbers of successful medical school applicants. Comparisons of data on these schools revealed several important factors that may be related to differences in acceptance rates: Those schools that devoted greater effort to premedical training (for example, advising students about how to prepare for medical school, curriculum development, maintaining premedical or pre-health professions offices and clubs--the staff of these offices provide students with information on medical or other health professions schools--to identify and recruit students) tended to have higher acceptance rates. * Schools with higher acceptance rates had larger proportions of biology and chemistry majors aspiring to medical and dental careers and stronger affiliations with medical schools than schools with lower acceptance rates.* Institutions with higher acceptance rates offered a broader range of externally sponsored enrichment programs; the highest medical school acceptance rates were found among those schools with continuing Health Careers Opportunity Program projects that served significant percentages of students interested in careers in medicine.* Mean Medical College Admission Test scores were somewhat lower for applicants from schools with lower acceptance rates, but the great variation in acceptance rates for these schools is not reflected in a comparable variation in the Medical College Admission Test scores.

Black or African American↗