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Biomedical subjects

D R Smith

Publications and source records attributed to D R Smith.

At least 199 records · Page 11Linked to original sources
PubMed1991

Medical apartheid. An American perspective.

The suppressive policies and practices of apartheid in South Africa have directly contributed to preventable morbidity and mortality in black Africans. Due to socioeconomic segregation ("functional apartheid"), America's citizens of color also suffer excess death and disability. Health status measurements in the United States confirm the failure of the current fragmented health care system to recognize or respond to the unmet need or the barriers that exist. Predictably, the changes needed to improve the health status of black South Africans are similar to those that are necessary to remedy the situation in the United States. Community-Oriented Primary Care is a health service provision model that holds promise as a comprehensive community-based strategy that can begin to address some of the shortcomings of the current medical care systems of both nations.

Black or African American↗
PubMed1991

Distinguishing African and European honeybee matrilines using amplified mitochondrial DNA.

Previous DNA studies have revealed that feral neotropical African bees have largely retained an African genetic integrity. Additional DNA testing is needed to confirm these findings, to understand the processes responsible, and to follow African bee spread into the temperate United States. To facilitate surveys, the polymerase chain reaction was utilized. African and European honeybee mitochondrial DNA (mtDNA) was identified through amplified segments that carry informative restriction site and length polymorphisms. The ability to discriminate among honeybee subspecies was established by testing a total of 129 colonies from Africa and Europe. Matriline identities could thus be determined for imported New World bees. Among 41 managed and feral colonies in the United States and north Mexico, two European lineages (west and east) were distinguished. From neotropical regions, 72 feral colonies had African mtDNA and 4 had European mtDNA. The results support earlier conclusions that neotropical African bees have spread as unbroken African maternal lineages. Old and New World African honeybee populations exhibit different frequencies of a mtDNA length polymorphism. Through standard analyses, a north African mtDNA type that may have been imported previously from Spain or Portugal was not detected among neotropical African bees.

Africa↗
PubMed1991

Reoxygenation-dependent decrease in mitochondrial NADH:CoQ reductase (Complex I) activity in the hypoxic/reoxygenated rat heart.

Reoxygenation of the hypoxic myocardium results in a number of processes, including an O2-dependent increase in total tissue Ca2+ and cell lysis in which mitochondrial electron transport plays a key role. In the present study we have isolated mitochondria from perfused rat hearts subjected to hypoxia and found no change in their respiratory function relative to controls. In contrast, mitochondria isolated immediately after reoxygenation of hypoxic-perfused hearts exhibited a specific and significant decrease in NADH:CoQ reductase (Complex I; EC 1.6.5.3) activity, as measured both polarographically and spectrophotometrically. Isolated cardiomyocytes subjected to a similar protocol of hypoxia/reoxygenation also exhibited a specific decrease in Complex I activity. Myocardial perfusion with media containing Ruthenium Red protected against the reoxygenation-dependent loss of Complex I activity. These observations taken together suggest that mitochondrial Ca2+ uptake on reoxygenation is implicated in the mechanism of the specific loss of Complex I activity.

Animals↗
PubMed1991

Purified glutathione S-transferases from parasites as candidate protective antigens.

Glutathione S-transferase (GST) activity was detected in larvae of the Australian sheep blowfly Lucilia cuprina, and in the nematode Haemonchus contortus. A specific inhibitor of the enzyme was shown to affect survival of both species of parasite in vitro. GST from both parasites has been purified and partially characterized. Antisera raised to the purified enzymes were shown to inhibit the enzyme activity in vitro. However, the antisera had no effect on the survival of either parasite.

Amino Acid Sequence↗
PubMed1991

Community responsive medicine: defining an academic discipline.

Academic medicine is entering a period of introspection created by changing patterns of health and disease and changing patterns in reimbursement and health policy. To respond to existing health challenges, innovative strategies for health care delivery and education must be devised. The migration of medical education and health care delivery into centralized and frequently difficult-to-access campuses is being reviewed by payors, policy analysts, and purchasers of care. One proposed solution to this problem responds to the identified shortcomings in medical education and some of the failures of our health care delivery system. Community Oriented Primary Care (COPC) and the related discipline of Community Responsive Medicine define health-oriented strategies that blend traditional primary care and public health. The classroom in Community Responsive Medicine is the community. The curriculum is defined by the elements and skills necessary to improve the health status of the target community. The model allows the student and resident to appreciate and experience the entire spectrum of health and disease and to understand the sequence of events that may lead to illness. Tertiary care is a critical curriculum component, but in Community Responsive Medicine the curriculum is balanced between the ambulatory and tertiary care settings. Community Responsive Medicine defines a role for new leadership that can create responsive educational and health care delivery systems accountable to the communities they serve.

Community Medicine↗
PubMed1991

Indian bunchy top disease of tomato plants is caused by a distinct strain of citrus exocortis viroid.

A viroid has been isolated from tomato plants affected by Indian bunchy top disease of tomato (Lycopersicon esculentum Mill.). In dot blot hybridization assays with 32P-labelled cRNA probes specific for the detection of various viroids, the Indian viroid was shown to be most closely related to the citrus exocortis viroid (CEVd). Sequence determination showed that the viroid consists of 372 nucleotides and confirmed its close relationship with CEVd. The viroid, for which we propose the acronym CEVd-t, differs from the Australian CEVd strains A and B by 36 and 47 nucleotides, respectively, and from the Spanish grapevine isolate by 52 changes. A phylogenetic analysis confirmed the closet relationship with CEVd in all structural domains, except the pathogenicity and left-terminal domains, which are closely related to the corresponding domains of the potato spindle tuber and tomato apical stunt viroids, respectively.

Base Sequence↗
PubMed1991

Skeletal concentrations of lead, cadmium, zinc, and silver in ancient North American Pecos Indians.

Bone samples of 14 prehistoric North American Pecos Indians from circa 1400 A.D. were analyzed for lead, cadmium, zinc, and silver by graphite furnace atomic absorption spectrometry to establish the baseline levels of these elements in an ancient North American population. Measurements of outer and inner bone fractions indicate the former were contaminated postmortem for lead, zinc, and cadmium. The contamination-adjusted average (mean +/- SD) level of lead (expressed as the ratio of atomic lead to atomic calcium) in bones of the Indians was 8.4 +/- 4.4 x 10(-7)), which was similar to ratios in bones of ancient Peruvians (0.9 to 7.7 x 10(-7)) and significantly lower than ratios in bones of modern adults in England and the United States (210 to 350 x 10(-7]. The adjusted average concentrations (microgram per gram dry weight) of biologic cadmium, silver, and zinc in the Pecos Indian bones were 0.032 +/- 0.013, 0.094 +/- 0.044, and 130 +/- 66, as compared to concentrations of 1.8, 0.01 to 0.44, and 75 to 170 in the bones of modern people, respectively. Therefore, cadmium concentrations in Pecos Indian bones are also approximately 50-fold lower than those of contemporary humans. These data support earlier findings that most previously reported natural concentrations of lead in human tissues are erroneously high and indicate that natural concentrations of cadmium are also between one and two orders of magnitude lower than contemporary concentrations.

Bone and Bones↗
PubMed1991

Chondroid chordoma: case report and literature review.

The case of a 74-year-old woman with chondroid chordoma is presented. This tumor is an uncommon variant of typical chordoma and occurs in less than 1% of all intracranial tumors. The mean age of occurrence is approximately 36 years, 38 years younger than the woman in this study. Classical symptoms of intracranial chordoma were noted in this patient, including headaches, diplopia, third nerve palsy and sixth nerve palsy. Differentiation of this tumor from classic chordoma is important because chondroid chordoma has a substantially superior progress.

Aged↗
PubMed1991

Childhood retroperitoneal fibrosis associated with a horseshoe kidney: a case report.

The case of a 12-year-old girl with retroperitoneal fibrosis and a horseshoe kidney is presented. This is a relationship that has not previously been described. An in-depth review of the literature of childhood retroperitoneal fibrosis is undertaken with accompanying discussion on the etiology, symptoms, pathology, radiographic findings, treatments and prognosis of the disease.

Child↗
PubMed1990

Chromatography and generation of specific antisera to synthetic peptides from a protective Boophilus microplus antigen.

Four oligopeptides corresponding to predicted antigenic regions of the protective Bm86 glycoprotein of the cattle tick Boophilus microplus were synthesized and purified. Three were conjugated to carrier proteins and antisera raised in rabbits and cows. All elicited antipeptide antibodies that recognized Bm86 and recombinant derived products in Western blots; however, only one produced antiserum capable of recognizing native Bm86 in an indirect immunofluorescence assay. Ticks fed in vitro on this antiserum showed no obvious gut damage.

Amino Acid Sequence↗
PubMed1990

Point mutation analysis of the Xenopus laevis RNA polymerase I core promoter.

The core region of the Xenopus laevis pre-ribosomal RNA promoter was subjected to point mutation analysis. A total of 27 point mutants within a 78 base pair region from -64 to +14, (relative to the start of transcription at +1), were assayed by oocyte microinjection. The results locate the 3' boundary of the core promoter at +4 and the 5' boundary at between -33 and -39 and suggest that this region of the Xenopus promoter is generally similar in organisation to mammalian core promoters. In particular, the conserved guanidine nucleotides at -7 and -16 are clearly essential for promoter function. The data suggest that interactions between the transcription machinery and the promoter occur in four distinct regions around +2 to +4, -7, -17 to -20 and -28 to -33. This particular periodicity of functionally important nucleotides is consistent with a model in which all protein-DNA interactions take place from predominantly one side of the DNA helix.

Animals↗
PubMed1990

Identification of two additional v-sea-encoded proteins in avian erythroblastosis virus, S13-infected fibroblasts.

Rabbit antibodies prepared against a v-sea-encoded polypeptide expressed in bacteria were used to characterize the v-sea-encoded proteins in cells transformed by the avian erythroblastosis virus, S13. In addition to the two previously described v-sea-encoded proteins, gp155 and gp70, two additional proteins were identified of molecular weights 38,000 and 36,000 Da. Interestingly, these two proteins were found only in fibroblasts infected with the S13 virus and not in S13-transformed erythroid cells. These two proteins were phosphoproteins, but, unlike the two previously characterized v-sea-encoded proteins, they did not appear to be modified by the addition of N-linked sugars. Possible mechanisms for the biosynthesis of these two new proteins are discussed.

Alpharetrovirus↗