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Biomedical subjects

S Smith

Publications and source records attributed to S Smith.

At least 685 records · Page 38Linked to original sources
PubMed1990

Fatal aortoesophageal fistula due to double aortic arch: an unusual complication of prolonged nasogastric intubation.

Fatal hematemesis occurred in a 3-month-old boy due to erosion by a nasogastric tube into the right component of an unrecognized double aortic arch. This is the youngest of six reported patients with arterioesophageal fistula in the literature. Including this patient, five of six had nasogastric tubes in place. The tube may have led to fistula formation by compression of the esophageal wall against an anomalous vessel. When a vascular ring is suspected, indwelling esophageal tubes such as nasogastric tubes should not be used.

Aorta, Thoracic↗
PubMed1990

The effect of plaque composition on laser recanalization.

Laser recanalization using metal-capped laser fibers and continuous-wave laser energy occurs by thermal ablation of atherosclerotic plaque. Different types of plaque respond differently to laser energy and plaque composition may be an important determinant of the success of laser recanalization. To investigate this hypothesis, 16 patients with symptomatic arterial occlusions in the mid and distal superficial femoral artery underwent B-mode ultrasound arterial imaging prior to attempted argon laser recanalization. The composition of the occlusions was classified as soft (echogenicity less than the adjacent arterial wall), dense (echogenicity equal to the adjacent arterial wall), or calcified (echoreflective). Recanalization was successful in 100% (8/8) of patients with soft occlusions versus 38% (3/8) with dense or calcified occlusions (P = 0.01). Thus, plaque composition as assessed by B-mode ultrasound imaging appears to be an important predictor of the success or failure of arterial recanalization using a thermal laser probe.

Aged↗
PubMed1990

Construction and analysis of linking libraries from the mouse X chromosome.

A hybrid cell line containing the mouse X chromosome on a human background has been used to construct linking libraries from the mouse X chromosome, and approximately 250 unique EagI and NotI clones have been identified. Seventy-three clones have been sublocalized onto the X chromosome using interspecific Mus spretus/Mus domesticus crosses and a panel of somatic cell hybrids carrying one-half of reciprocal X-autosome translocations. The average spacing of the linking clones mapped to date is about one every 2 Mb of DNA. Two clones from the central region of the chromosome have been physically linked by pulsed-field gel electrophoresis. A large number of clones contain conserved sequences, indicating the presence of CpG-rich island-associated genes. The clones isolated from these libraries provide a valuable resource for comparative mapping between man and mouse X chromosomes, isolation of X-linked disease loci of interest by reverse genetics, and analysis of the long-range structure and organization of the chromosome.

Animals↗
PubMed1990

Physical mapping of probes within 14q32, a subtelomeric region showing a high recombination frequency.

The genetic linkage map of chromosome 14q32 contains 11 loci which span a distance of more than 60 cM. We have assigned 10 of these loci and the AKT1 proto-oncogene to segments of 14q32, using breakpoints derived from four independent chromosomal deletions or rearrangements. The most telomeric breakpoint was found in a proband (HSC 6) carrying a ring-14 chromosome. HSC 6 is monosomic for the distal part of 14q32, which contains the immunoglobulin heavy-chain locus (IGH), and random markers D14S20, D14S19, and D14S23. Two other chromosomal breakpoints, found in probands HSC 121 and HSC 981, could not be distinguished from each other using DNA probes, although the cytogenetic breakpoints appeared to be different at 14q32.32 and 14q32.31, respectively. The region between the breakpoints of HSC 6 and HSC 121 contains AKT1, D14S1, D14S17, and D14S16. The entire telomeric band 14q32 is assumed to contain about 10% of chromosome 14, or approximately 10 Mb. The 8 most telomeric loci, including D14S1, map to 14q32.32-qter, which measures only several megabases. However, these loci span a genetic distance of 23 cM. The high recombination frequency contrasts with the observation that two of the gamma genes in the IGH constant region show a high degree of linkage disequilibrium, though 180 kb apart. This finding suggests that a telomeric localization per se does not lead to a higher recombination frequency and favors the hypothesis that the higher recombination frequency at the telomeres may be due to specific "hot spots" for recombination.

Blotting, Southern↗
PubMed1990

Organ distribution of gut-derived bacteria caused by bowel manipulation or ischemia.

Translocation of carbon-14-labeled Escherichia coli from the gut was studied at the specified times in the following groups of rats: Group 1, 5 hours after ligation of the superior mesenteric artery; Group 2, 5 hours after laparotomy and exposure of the superior mesenteric artery with gentle removal and replacement of the intestines; and Group 3, 5 hours after handling but no surgical manipulation. Both living and dead bacteria were administered by means of gavage, and the effect of viability, intestinal ischemia without reperfusion, and bowel manipulation on the translocation of enteric bacteria was assessed. We demonstrated that (1) even gentle bowel manipulation causes bacteremia as great as that associated with ligation of the superior mesenteric artery; (2) dead E. coli are absorbed into the blood in the presence of bowel manipulation or ischemia but less effectively than are live E. coli; (3) live bacteria are found in highest concentration in the lung and in descending order in the liver, kidney, heart, and spleen; (4) dead bacteria absorbed from the gut are found in highest concentration in the kidney and the liver. Lesser amounts are found in the lung, spleen, and heart.

Administration, Oral↗
PubMed1990

Stress and the heart: biobehavioral aspects of sudden cardiac death.

Stress has been implicated as a developmental factor in atherosclerotic heart disease, essential hypertension, and sudden cardiac death. This article reviews the mechanisms and biobehavioral effects of stress on the heart, focusing on its relation to sudden cardiac death. Epidemiologic evidence, cultural studies, animal experiments, and human research are reviewed to better understand the biobehavioral aspects of stress on the heart. Emphasis is placed on understanding the interaction of the central nervous system's frontal cortex and hypothalamus with cardiovascular control areas. With today's understanding of the frontal cortex and the interaction of hormones and neurotransmitters with the cardiovascular system, clinical interventions utilizing psychotherapy and psychopharmacology are needed, particularly since both approaches are underutilized in combating arrhythmias.

Animals↗
PubMed1990

Time course of vitamin E repletion in the premature infant.

Plasma and erythrocyte (RBC) tocopherol-isomer concentrations were determined serially in forty-two premature infants (25-35 weeks gestation) from birth to 8 weeks of age. For comparison purposes vitamin E status was also determined in six term infants over the first 8 d following birth and in a group of thirteen adult volunteers. Vitamin E intakes in term and preterm infants were calculated from recorded food intakes and blood transfusions. In term infants plasma vitamin E concentration rose from 1.9 mg/l (day 1) to 8.2 mg/l by day 8. In comparison preterm plasma vitamin E concentration, 0.3 mg/l (day 1), did not change appreciably by day 8 (0.7 mg/l). Likewise RBC vitamin E concentration increased in term infants from 1.3 mg/l (day 1) to 2.7 mg/l (day 8), while in preterm infants it remained unchanged, 1.5 mg/1 (day 1) v. 1.3 mg/l (day 8). Over the 3 weeks following birth, RBC vitamin E concentrations in the premature infants increased to adult values, while plasma vitamin E concentration did not reach the adult range until 8 weeks post-term. These slow changes in plasma vitamin E status occurred even though the vitamin E intake of these infants was similar to that proving adequate for term infants.

Adult↗
PubMed1990

Dissociation between maternal and fetal toxicity of methyl isocyanate in mice and rats.

The contribution of maternal hormonal changes and pulmonary damage on the fetal toxicity of methyl isocyanate (MIC) was studied in mice and rats. Exposure to MIC decreased maternal plasma progesterone levels in mice that lost but not in mice that retained pregnancy. Fetal toxicity of MIC was not related to changes in maternal plasma corticosterone levels. Neither chronic administration of progesterone nor the suppression of pulmonary edema with dexamethasone decreased fetal toxicity of MIC. Embryos exposed in utero or in vitro to MIC vapor exhibited a concentration-dependent decrease in growth in culture. An acute dose (3 mmol/kg) of the MIC metabolites (methylamine, dimethylamine, trimethylamine, dimethyl urea) did not exert fetal toxicity. These data suggest that the fetal toxicity of MIC is partly independent of maternal toxicity and may result from its transfer across the placenta and interaction with fetal tissues.

Administration, Inhalation↗
PubMed1990

Non-Hodgkin's lymphomas of the gastrointestinal tract. An evaluation of paraffin section immunostaining.

Although the gastrointestinal (GI) tract is the most common site of primary extranodal lymphomas, the lineage of these tumors has been controversial. The authors used paraffin-reactive antibodies detecting markers of B-, T-, histiocytic, and epithelial cells to study 34 non-Hodgkin's lymphomas of the GI tract for which unequivocal frozen-section immunophenotypine was available as a control to determine whether these antibodies are reliable in the study of these tumors. Frozen-section studies revealed 31 tumors of B-cell origin and three T-cell tumors. Paraffin-reactive antibodies confirmed B-cell lineage in 28 of the 31 cases, with equivocal results in the remaining three. Only one of the T-cell lymphomas was identified in paraffin studies. Our results indicate that paraffin-reactive antibodies can reliably identify most B-cell lymphomas in the GI tract but may be unreliable in the detection of lymphomas of T-cell origin.

Adult↗
PubMed1990

Serum oncogene proteins in foundry workers.

A new technique for detecting oncogene activation based on immunoblotting for oncogene proteins in serum has been applied to screen a cohort of foundry workers with well-defined workplace exposures to polycyclic aromatic hydrocarbon carcinogens. Three of the 18 individuals screened were found to have abnormal expression of the proteins of the ras and fes oncogenes. These three individuals were known to have had medium to high workplace exposures to benzo(a)pyrene and to have correspondingly high levels of benzo(a)pyrene-DNA adducts in their peripheral leukocytes. No individuals among the unexposed controls were found to have abnormal serum oncogene protein expression. These results suggest the feasibility of using serum oncogene proteins along with DNA-carcinogen adducts as potential molecular epidemiological markers in exposed worker populations; further, larger scale studies will be necessary to demonstrate the utility of these markers for identifying individuals at risk for the development of malignant disease due to their occupational exposures.

Biomarkers, Tumor↗
PubMed1990

Organ distribution of radiolabeled enteric Escherichia coli during and after hemorrhagic shock.

Translocation of intestinal bacteria to the blood during hemorrhagic shock (HS) has been confirmed in rats and humans. The current study was designed to trace the path of translocated intestinal bacteria in a murine HS model. Thirty-one rats were gavaged with 1,000,000 counts of viable 14C oleic acid-labeled Escherichia coli. Forty-eight hours later the animals were bled to 30 mmHg until either 80% of their maximal shed blood was returned or 5 hours of shock had elapsed and they were resuscitated with Ringer's lactate as previously described. Control animals were cannulated but not shocked. Eight rats immediately after shock and resuscitation, 6 rats 24 hours after shock, 3 rats 48 hours after shock, and 4 animals that died in shock had their heart, lung, liver, spleen, kidney, and serum harvested, cultured, and radioactive content measured. Translocated enteric bacteria are found primarily in the lung immediately after shock with redistribution to the liver and kidney 24 hours later. Animals surviving to 48 hours were capable of eliminating the majority of the bacteria from their major organ systems. Positive cultures for E. coli were also found in the blood, lung, liver, and kidney. We speculate that the inflammatory response stimulated by the bacteria in these organs may contribute to the multiple-organ failure syndrome seen after HS.

Animals↗
PubMed1990

Cost effectiveness of trauma quality assurance audit filters.

The American College of Surgeons Committee on Trauma (ACSCOT) has published recommended minimal audit filters for trauma quality assurance. In this study ten filters were assessed through variable sample sizes over a 1-year period for cost and efficiency. Each filtered case was screened by trauma nurse coordinators. The trauma director reviewed possible deviations from standard and presented cases at peer review conferences for consensus on problem identification. While several filters had reasonable yield, most filters had minimal or no yield. Ten de novo problems were identified at a cost of +1,000 per de novo problem. Six filters were modified based on common reasons for overfiltration, resulting in a substantial reduction in filtration rate without losing problem identification. We conclude that ACSCOT audit filters 1 (unexpected deaths), 4 (ICU LOS greater than twice the average), 5 (trauma surgeon response), and 9 (major surgery greater than 24 hours) have a reasonable yield. Filters 2, 3, 7, 8, 11, and 12 have limited value to an established suburban trauma center and are not cost effective. Modifications of these filters can reduce cost without obvious impact on effectiveness. Specific audit filters recommended for future study are presented.

Cost-Benefit Analysis↗
PubMed1990

Effect of Potassium Levels on the Stomatal Behavior of the Hemi-Parasite Striga hermonthica.

The hemi-parasite Striga hermonthica, exhibits an anomalous pattern of stomatal response, stomata remaining open in darkness and when subjected to water stress. This suggests irregularity in stomatal response due to malfunction of the stomatal mechanism. To test this suggestion guard cells were isolated from the effects of surrounding cells, by incubating epidermal strips at low pH. These stomata responded rapidly to low CO(2) concentrations, darkness, and ABA. Thus, a paradox exists between stomatal behavior observed in whole leaves and that in isolated guard cells. However, when incubated in the presence of high potassium concentrations (>200 millimolar KCl) stomatal responses in epidermal strips resembled those found in whole leaves, with enhanced opening and reduced closing responses. It is suggested that the anomalous behavior of stomata in Striga and other leafy hemiparasites can be explained by the modulatory effects of high potassium concentrations which accumulate in the leaves as a consequence of high transpiration rates and the lack of a retranslocation system.

Journal Article↗
PubMed1990

Segmental neurofibromatosis in an octogenarian.

A case of segmental neurofibromatosis (SNF) in an octogenarian is presented. The patient's lesions were first noted when he was 74 years of age. This variant of neurofibromatosis (Riccardi's classification, NF-V) is most typically seen in childhood or young adulthood. To the best of our knowledge, our patient's SNF is the first case to present in the eighth decade of life. Physicians working with geriatric patients should be aware of this entity and its lack of genetic heritability or systemic manifestations.

Age Factors↗
PubMed1990

Macrophages cultured in vitro release leukotriene B4 and neutrophil attractant/activation protein (interleukin 8) sequentially in response to stimulation with lipopolysaccharide and zymosan.

The capacity of lipopolysaccharide (LPS), zymosan, and calcium ionophore A23187 to induce neutrophil chemotactic activity (NCA), leukotriene B4 (LTB4), and neutrophil attractant/activation protein (NAP-1) release from human alveolar macrophages (AM) retrieved from normal nonsmokers was evaluated. LPS induced a dose-dependent release of LTB4 that began by 1 h, 4.0 +/- 3.2 ng/10(6) viable AM; peaked at 3 h, 24.7 +/- 13.5 ng/10(6) viable AM; and decreased by 24 h, 1.2 +/- 1.0 ng/10(6) viable AM (n = 8). Quantities of LTB4 in cell-free supernatants of AM stimulated with LPS were determined by reverse-phase high-performance liquid chromatography and corresponded well with results obtained by radioimmunoassay. By contrast, NAP-1 release began approximately 3-5 h after stimulation of AM with LPS, 197 +/- 192 ng/ml, and peaked at 24 h, 790 +/- 124 ng/ml. Release of NAP-1 was stimulus specific because A23187 evoked the release of LTB4 but not NAP-1, whereas LPS and zymosan induced the release of both LTB4 and NAP-1. The appearance of neutrophil chemotactic activity in supernatants of AM challenged with LPS for 3 h could be explained completely by the quantities of LTB4 present. After stimulation with LPS or zymosan for 24 h, AM had metabolized almost all generated LTB4. Preincubation of AM with nordihydroguiaretic acid (10(-4) M) completely abolished the appearance of NCA, LTB4, and NAP-1 in supernatants of AM challenged with LPS. Therefore, LPS and zymosan particles were potent stimuli of the sequential release of LTB4 and NAP-1 from AM.

Calcimycin↗
PubMed1990

Towards breaking the cycle of intergenerational abuse.

A quantitative single case study of an adolescent mother with a history of being abused as a child is presented. It illustrates the diagnostic and treatment issues during an intervention designed to break the cycle of intergenerational abuse. Drawing upon an ecological, transactional model of development, the case study utilized a multimethod, longitudinal approach to assess the mother's history and current psychosocial functioning, the infant's developmental competence and attachment status, patterns of mother-infant interaction and components of the family's social ecology. Measures were administered during a baseline period and systematically repeated throughout the one-year period of intervention. The treatment involved two weekly therapy sessions; one, an individual session for the mother and the other, a session in which mother and infant were seen together. The findings at the one-year evaluation showed improved maternal psychosocial functioning, the infant's shift from an insecure to a secure attachment classification and improved patterns of mother-infant interactions. The implications of this therapeutic approach and the use of single-case methodology are discussed.

Adolescent↗
PubMed1990

The stigma of AIDS: fear of disease and prejudice toward gay men.

Three hundred college students were presented with vignettes describing an ill person; the vignettes were identical except the illness was identified as either AIDS or leukemia and the individual was described as either homosexual or heterosexual. After reading one vignette, each subject completed a set of measures sensitive to interpersonal evaluation, prejudicial attitudes, and willingness to interact casually with the portrayed individual. The findings indicate the presence of highly stigmatizing attitudes towards AIDS patients and suggest that the public views AIDS patients and gay persons with similar attitudinal prejudice. The need for greater attention to AIDS by social and behavioral researchers is discussed.

Acquired Immunodeficiency Syndrome↗