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Biomedical subjects

D G Johnson

Publications and source records attributed to D G Johnson.

At least 235 records · Page 13Linked to original sources
PubMed1975

Trends in surgery for childhood rhabdomyosarcoma.

Total excision remains the aim of surgical management for rhabdomyosarcomas in children, but effective adjunctive treatment for the majority of these tumors permits preservation of function and appearance in situations where formerly these were sacrificed. Control of residual tumor in microscopic quantity can now be achieved by chemotherapy in the majority of cases. The coordination of surgery, irradiation, and chemotherapy has reduced the need for ultra-radical extirpative procedures. The following conservative trends have evolved: 1) Amputations are rarely indicated for tumors of the extremities. 2) Primary irradiation for orbital tumors may obviate exenteration and save the eye. 3) Multilating excisions for head and neck tumors can often be avoided. 4) Prophylactic regional lymph node dissections are usually not indicated. 5) Primary tumors of the bladder or prostate can usually be managed by anterior exenteration.

Adolescent↗
PubMed1975

Management of acquired tracheal obstructions in infancy.

Endoscopic resection of tracheal subglottic stenosis can be performed safely and effectively. With careful selection, some stenotic rings can be excised without the requirement for prior tracheostomy. Endoscopic resection does not supplant other methods of dilatation, injection, or stenting of subglottic scars, but early resection in appropriate cases may reduce the number of dilatations and obviate the need for a stent and systemic steroids.

Dilatation↗
PubMed1975

Recruitment and progress of minority medical school entrants 1970-1972.

This is a report on a national study of minority group applicants and entrants to the 1970, 1971, and 1972 entering classes of U.S. medical colleges. The aim of the investigation was to further understanding of the factors involved in attempting to increase minority representation in education for the practice of medicine. Data from the Association of American Medical Colleges are used to examine characteristics of successful and unsuccessful minority applicants to medical school. Socieconomic, personal, institutiona, and geographical factors that relate to the recruitment and progress of minority students in medicine are analyzed and evaluated. Differences between Caucasian and minority group students affecting admissions, retention, and promotion are documented. The investigators also compare the projections of a 1970 AAMC task force report with actual occurrences in the national effort to expand educational opportunities in medicine for blacks and other underrepresented minority students (that is, American Indians, Mexican Americans, and mainland Puerto Ricans). This comparison shows substantial progress toward the projected figures but a need for renewed commitment if they are to be reached. Suggestions are offered for improving the recruitment and progress of minority medical school entrants by such means as the AAMC Simulated Minority Admissions Exercises and by ongoing programs at individual medical schools. The study also yielded such pertinent findings as the following: 1. Confirmation that the racial characterizations self-reported by medical school applicants have a high degree of accuracy and an increasing degree of completeness. 2. An encouraging increase in the number of black premedical students who will potentially apply for the medical school classes entering in 1976 and 1977. 3. Growth in the enrollment of low-income medical students, most of it explained by the increase in the numbers of minority group members who have been admitted in recent years. 4. More mobility among blacks than Caucasians with regard to attending medical schools in other than their region of legal residence. 5. A higher proportion of women, of older, and of married students among minority medical school matriculants than among Caucasian matriculants. 6. A slightly higher medical school retention rate for Caucasians than for students from underrepresented minority groups, possibly explained in part by the greater diversity in the socioeconomic and educational backgrounds of the latter. 7. A positive relationship for blacks between the size of undergraduate college attended and successful completion of the first year of medical school.

Black or African American↗
PubMed1975

Retention by sex and race of 1968-1972 U.S. medical school entrants.

With expanding class sizes and increased proportions of women and minority group medical students, questions are frequently asked concerning recent trends in retention and graduation rates. In this article the authors report on a national Association of American Medical Colleges study of new entrants in the 1968 through 1972 first-year classes of U.S. medical schools and place this study in historical perspective. They note that recent attrition rates are only about half that of the 9 percent reported in the last national AAMC study of 1949-1958 entrants. Although the retention rate for women and for underrepresented minorities is still slightly less than that for white males, the gap appears to be narrowing. Suggestions for optimum retention include: (a) enlarging the pool of minority applicants, (b) improving the techniques of student selection, and (c) increasing the flexibility of academic programs in the medical schools.

Achievement↗
PubMed1975

Study of U.S. medical school applicants, 1973-74.

This annual study reports applicant, application, and enrollment statistics for the 1973-74 entering class of the 114 U.S. medical schools in comparison with previous years. National totals in all categories are larger than ever before, but the annual rate of increase is declining. Traditional tables reflect five years of historical data (1969--70 through 1973--74), while new features for the 1973 study concentrate on: (a) acceptance success for first-time and repeat applicants, (b) rankings of state acceptance ratios, and (c) ability levels by acceptance success and by application frequency. The study concludes with an outline of specific efforts by the Association of American Medical Colleges to assist medical schools in coping with the continuing three-to-one imbalance between numbers of applicants and numbers of first-year places.

Achievement↗
PubMed1975

Inhibition of glucagon and insulin secretion by somatostatin in the rat pancreas perfused in situ.

Perfusion of growth hormone inhibitory factor (somatostatin) into rat pancreas inhibited secretion of glucagon and insulin into medium containing 5.5 mM glucose. A 15-min infusion of arginine (20 mM) greatly increased glucagon and insulin secretion. When perfused simultaneously with arginine, somatostatin (55 nM) abolished the increase in glucagon secretion. The acute phase of insulin secretion in response to arginine was attenuated by somatostatin, and subsequent secretion was decreased to control levels. Pretreatment for 5 min with somatostatin blocked even acute-phase insulin secretion in response to arginine. Somatostatin did not affect basal or glucose-stimulated secretion of insulin from rat pancreatic islets isolated by the collagenase technique. Arginine-stimulated secretion of insulin was enhanced by somatostatin in isolated islets. These results demonstrate a direct effect of somatostatin on the pancreas to inhibit secretion of glucagon and insulin. The failure of somatostatin to inhibit insulin secretion in pancreatic islets may be due to alterations in the beta cells produced by the isolation procedure. It is also possible that the effect of somatostatin on insulin secretion may be mediated indirectly.

Animals↗
PubMed1975

Inhibition of gastrin release by somatosatin in vitro.

An in vitro system which uses perifused pieces from the antrum of rat stomach has been used to study the effect of dihydrosomatostatin on gastrin release. The gastrin concentration in fractions of the perfusate was measured by radioimmunoassay. Dihydrosomatostatin (2 x 10-7M) had no effect on basal gastrin levels but virtually abolished the biphasic response seen with argine stimulation. The study demonstrates close functional similarities between G cells and pancreatic islet cells.

Animals↗
PubMed1974

Maternal mortality in Papua New Guinea 1971 and 1972.

Reports were received on 364 of the unknown number of maternal deaths that occurred in Papua New Guinea during the two years, 1 January, 1971 to 31 December, 1972. Postpartum haemorrhage accounted for 39 per cent of the deaths, puerperal sepsis for 19 per cent and associated conditions for 14 per cent. In 13 per cent of cases the cause of death could not be ascertained. Obstructed labour caused 4 per cent of the deaths, ruptured uterus 4 per cent, antepartum haemorrhage 3 per cent and abortion 3 per cent. Three deaths were due to miscellanous causes. It is possible that three of the deaths (0.8 per cent of the total) in the cause unascertained group were due to toxaemia of pregnancy. In the coastal districts the major cause of death was postpartum haemorrhage (53 per cent) and the major high-risk factor was grand multiparity (5 or more). In the highlands the major cause of death was puerperal sepsis (41 per cent) and the major high-risk factor was nulliparity. About 50 per cent of all pregnant women in Papua New Guinea are seen at antenatal clinic and about 25 per cent of all births occur in hospital or heath centre. Forty-four per cent of the women who died (abortion excluded) were seen at antenatal clinic and 18 per cent were delivered in hospital or health centre. High-risk factors were present in 87 per cent of women who were seen at antenatal clinic, but only 28 per cent of these high-risk women were delivered in hospital or health centre. Extension of the antenatal services will not result in a major reduction in maternal mortality unless high-risk factors are recognised and unless high-risk mothers can be persuaded to have their babies in hospital or health centre.

Female↗
PubMed1974

Perinatal mortality at the Port Moresby General Hospital and St. Therese's Maternity Hospital 1972.

A study was made of the 67 still-births and the 58 neonatal deaths that occurred among the 3,516 viable infants (birth weight 1,000 g. or more) that were born to public patients of the obstetric units of Port Moresby General Hospital and St. Therese's Maternity Hospital during the year 1972. The combined stillbirth and neonatal mortality rate was 35.5 per 1,000 births. The adverse effects of lack of antenatal care, delivery outside hospital, high parity, maternal anaemia, mulitple pregnancy, and low birth weight are demonstrated. Low birth weight (1,000 to 2,200 g.) of unknown cause accounted for 24.0 per cent of the deaths. In 16,8 per cent of cases the birth weight was more than 2,200 g. and the cause of death was unknown. Birth trauma accounted for 19.2 per cent of the deaths, congenital malformation for 11.2 per cent, antepartum haemorrhage for 11.2 per cent, toxaemia for 10.4 per cent, and maternal disease for 3.2 per cent. There were miscellaneous causes in 4.0 per cent of cases. Approximately 75 per cent of the deaths were considered to be the result of unfavourable factors in the mother's environment. Approximately 14 per cent were primarily the result of obstetric complications and might have been avoided by a higher standard of obstetric care. Improving the standard of obstetric care that is presently available in Port Moresby would probably reduce the perinatal mortality rate by not more than 5 per 1,000.

Birth Weight↗