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Biomedical subjects

S Cho

Publications and source records attributed to S Cho.

At least 217 records · Page 12Linked to original sources
PubMed1987

Enhanced antibody responses in mice by combined administration of interferon with rabies vaccine.

Exogenous interferon administered to mice at the time of, and 6 hours after the first dose of 3 daily vaccinations accelerated and enhanced the IgM and IgG antibody responses to rabies virus. The effect of interferon was not evident when the interferon was administered later in the vaccination schedules and was abrogated by prior administration of anti-interferon antibody to the mice. The number of IgM antibody secreting cells in the spleen was significantly greater in mice treated with interferon than in controls.

Animals↗
PubMed1987

The pediatric nephrologist's dilemma: growth after renal transplantation and its interaction with age as a possible immunologic variable.

Two important criteria for successful end-stage renal disease therapy in children are achievement of optimal growth and possession of a well-functioning renal transplant. We describe eight children with accelerated post-transplant growth. Accelerated and even catch-up growth was achievable if the transplant occurred at an early age (less than 9 years), the daily dose of prednisone was low (less than or equal to 0.24 mg/kg/d), and renal function was excellent (creatinine clearance greater than or equal to 89 mL/min/1.73 m2). However, the benefit to growth of transplanting a kidney in young children may be offset by reduced cadaver graft survival in children younger than 6 years. To study whether the less favorable graft survival was attributable to an increased immunologic responsiveness in the younger child, we examined three tests of nonspecific immune responsiveness, each of which, when increased, may indicate a propensity toward rejection: total T cell absolute number, T helper/suppressor ratio, and spontaneous blastogenesis. Each measurement was significantly increased in 20 uremic children 5 years old or younger, compared with 81 children 6 to 23 years of age. These data suggest that improved growth may be attained by transplanting a kidney in the young child with end-stage renal disease, but the young child may be at increased risk for rejection. This hypothesis suggests that for optimal rehabilitation, strategies should take into account the unique needs of the young child.

Adolescent↗
PubMed1987

A nonflow basis for the vulnerability of the subendocardium.

The functional consequences of a transmural gradient of metabolism in the heart were studied in 19 dogs. The technique of retrograde blood flow diversion after coronary occlusion was used to deplete the ischemic myocardium of blood flow. Blood flow was uniformly and equally depleted in all layers, averaging 0.044 ml/min per g. With oxygen supply a controlled variable, transmural differences in metabolic demand can be addressed. In groups of dogs severe myocardial ischemia was induced for periods of 20 to 90 minutes. No necrosis was noted after 20 minutes of ischemia. Beginning at 30 minutes of blood flow depletion, necrosis progressed from the endocardium toward the epicardium in a "wave front" pattern. At 90 minutes of ischemia, approximately 70% of the area at risk was necrotic. Thus, the relative vulnerability of the endocardium as compared with the epicardium is due to nonflow factors, and probably dictated by transmural differences in metabolic activity. It would appear that myocardial metabolism as compared with blood flow occupies a primary and overriding role during the first 20 minutes of ischemia. Furthermore, differences in transmural metabolism also dictate subendocardial vulnerability for ischemic periods greater than 20 minutes, irrespective of blood flow. The role of blood flow in these events may be to modulate the rate of the transmural wave front of progressing necrosis after 20 minutes of ischemia.

Animals↗
PubMed1987

Cumulative toxicity potential of methomyl aerosol by repeated inhalation.

There are few investigations concerning the cumulative toxicity of agricultural chemicals by repeated inhalation. In this study, Wistar male rats were exposed to methomyl powder (mass median aerodynamic diameter, 4.4 microns) for a single 4-hr exposure, or for 4 hr/day, 5 days/week for 3 months. The average exposure concentrations were controlled at 9.9 mg/m3 for the single exposure and at 14.8 mg/m3 for repeated exposures by a dust generator consisting of a continuous fluidized bed with an overflow pipe and a screw feeder. After the repeated exposures, plasma and red cell cholinesterase activities, and lipid concentrations of the rat lungs were measured and histopathological examinations were performed. There was no evidence of cumulative effects on the red cell cholinesterase activity, histopathological changes and lipid concentration in 3-month repeated inhalation.

Aerosols↗
PubMed1987

Murine T cell clones directed to rabies virus: isolation and some of their properties.

Seventeen Thy-1+ cell clones were induced in A/J mice immunized with the HEP-Flury strain of rabies virus after repeated stimulations with antigens in vitro. Ten clones with cell surface phenotypes Thy-1+, Lyt-1-,2+ were cytotoxic T lymphocytes (CTL) which lysed the virus-infected target cells under H-2 restriction. Target cells expressed the G and M2 structural proteins of rabies virus on their surface; however, target lysis by CTL clones was not blocked by anti-rabies antibody or by monoclonal antibodies to these proteins. All of the CTL clones efficiently and equally lysed target cells infected with three different strains of rabies virus and were cross-reactive for target cells infected with one (Duvenhage virus) of three different rabies serogroup viruses. Another five clones having phenotype Thy-1+, Lyt-1+,2- did not show any cytotoxic activity. The proliferation response of these clones to antigen stimulation was virus-specific and H-2-restricted. These clones were able to grow in culture medium without any or with the addition of low concentrations of T cell growth factor, in contrast to CTL clones, and were considered to be helper T lymphocytes (HTL). Both CTL and HTL clones produced gamma-interferon in response to antigen stimulation. The remaining two clones were Thy-1+, Lyt-1-,2-, asialo-GM1+, and were not cytotoxic to target cells even in the presence of anti-rabies antibody but were cytotoxic to YAC-1 cells. Further studies with these clones should allow us to investigate more closely the role of T cells in the pathogenesis of rabies.

Animals↗
PubMed1987

Partial duplication 16q: report of two affected siblings resulting from a maternal translocation and literature review.

Two siblings with a partial duplication 16q, born to a woman with a balanced translocation (6;16), are described. The first infant died at 8 weeks of age; the second died at 4 months. Fifteen other cases of duplications involving 16q have been reported, all of them derived from a balanced parental translocation. The most frequent physical findings have included dysmorphic facies characterized by high forehead, prominent nose, antimongoloid slant, malformed ears, and micrognathia, as well as flexion contractures of the joints, deformity of the feet, and genital hypoplasia in the male. Anorectal, intestinal and cardiac malformations were less frequent findings. Most of the affected infants died at ages ranging from 8 days to 6 months. The few with longer survival (up to 6 years) had a shorter, more distal segment duplication of chromosome 16. Although intrauterine growth retardation and microcephaly were not always present at birth, most of the infants had postnatal growth failure. The phenotypic and clinical findings of the two infants in this report are compared with those of previously reported cases, from which there appears to be correlation of the length of the 16q duplication with clinical phenotype and survivals.

Abnormalities, Multiple↗
PubMed1986

Isopycnography of intact cells. VI: Effect of temperature on steady state Escherichia coli.

Steady state cultures of Escherichia coli W3110 possess constant cellular concentrations of ribosomes while above 22 C as measured isopycnographically. Below 22 C, ribosome levels are significantly diminished, equivalent to those found in dormant cells. Concommitantly, the energy of activation of steady state population growth in E. coli remains at a constant 18.6 kcal between 22 C and 37 C. This suggests that the thermal stability of the protein synthesis apparatus may play an important role in pathogenesis as well as in other areas of ecological niche acquisition and dominance.

Escherichia coli↗
PubMed1985

Effect of iso-propyl-thio-beta-D-galactoside concentration on the level of lac-operon induction in steady state Escherichia coli.

In steady state E. coli cells growing at their maximal rate in broth, maximum induction of beta-galactosidase occurs at 0.10 mM isopropyl-thio-beta-D-galactoside (IPTG). Although induction of lac is near zero in steady state cells that are growing in 0.01 mM IPTG, induction at mildly subdued levels persists down to at least 0.001 mM in post-steady state cultures. Meanwhile, thiogalactoside transacetylase remains uninduced over the full range in which the cells are in steady state.

Acetyltransferases↗
PubMed1985

Lateral border zone: quantitation of lateral extension of subendocardial infarction in the dog.

This study was undertaken to quantitate the lateral extension that occurs concomitantly with the transmural extension of a subendocardial infarction. A subendocardial infarct was produced in 12 dogs by a 40 minute temporary coronary artery occlusion. Infarct extension was induced 7 days later by permanent occlusion of the same vessel. Regional myocardial blood flows confirmed that ischemia had been produced with both coronary artery occlusions. The vascular boundaries between the normally perfused and ischemic beds were defined by perfusion with different-colored Microfil solutions. The extent of subendocardial infarction and subsequent transmural and lateral extensions were assessed by point counting of histologic specimens. The initial temporary occlusion produced a 30.0 +/- 4.2% transmural infarct and the subsequent permanent occlusion a 29.2 +/- 3.5% transmural extension in a risk region of 39 +/- 4 g. Lateral extension was not measured in four dogs because the initial subendocardial infarct was patchy with markedly irregular lateral borders. In eight dogs the size of the measured lateral infarct extension from each lateral margin from two histologic sections was 0.63 +/- 0.013 cm2. The area of both lateral extensions was 1.7 +/- 0.1% of the cross-sectional area of its risk region as determined by planimetry. Using a model of the risk region, the mass of the lateral extension was estimated to be 1.4 +/- 0.3 g or 3.5 +/- 0.6% of the region at risk. Thus, at the lateral margin of a subendocardial infarct there is a border zone that is small relative to the size of the region at risk and infarcted myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Smooth muscle contraction bands in the media of coronary arteries: a postmortem marker of antemortem coronary spasm?

To date, no unequivocal morphologic markers have been described that would allow the diagnosis of coronary artery spasm to be made at autopsy. The coronary arteries of 63 adult patients without myocardial infarction were examined at autopsy, and the presence of medial smooth muscle contraction bands in these vessels was correlated with other vascular changes, myocardial pathologic changes and clinical history. These contraction bands have not been reported previously in human coronary arteries, but they were identified in experimental vascular spasm induced with catecholamines. It was found that 47 of the 63 cases were positive for contraction bands. As evidence of an antemortem process, there was a significant correlation between these changes and the presence of nonocclusive microthrombi, found in 25 cases. Contraction bands were also highly correlated with atherosclerotic plaque ruptures and mural plaque hemorrhages, which may be secondary to coronary spasm. In 78.7% of the cases positive for contraction bands, the cause of death was related to a diagnosis possibly associated with high catecholamine levels. On the basis of experimental evidence and the correlations identified in this study, coronary artery medial smooth muscle contraction bands may represent a postmortem marker of antemortem coronary spasm.

Adult↗
PubMed1985

Abnormalities of the coronary microcirculation in acute murine Chagas' disease.

Chronic Chagasic heart disease has many features characteristic of other congestive cardiomyopathies, including ventricular and atrial chamber enlargement, hypertrophy, focal scarring, and mural thrombi. Histologically, there is often lymphocytic inflammation, spotty necrosis, and few parasites. Although immunologic mechanisms have been invoked to explain the development of myocardial degeneration, there have been suggestions that the focal alterations in the heart are secondary to abnormalities of the coronary microcirculation. Based on work from our laboratories which has demonstrated microvascular hyperreactivity in several other models of congestive cardiomyopathy, we investigated whether the cardiac microcirculation of mice acutely infected with Trypanosoma cruzi was also abnormal. We perfused animals at 15-17 days post-infection with silicone rubber which fills the arterioles, capillaries, and venules of the beating heart. After clearing the tissue, we observed numerous areas of focal vascular constriction, microaneurysm formation, dilatation, and proliferation of microvessels which were not present in control animals. These lesions were similar to those we have observed in other congestive cardiomyopathies. Since at this stage of infection there is minimal cardiac degeneration or fibrosis, the presence of these vascular lesions even early in Chagas' disease, may be significant for the pathogenesis of focal myocardial damage. These observations during acute infection provide additional support for the suggestions of others that the myocardial microcirculation is abnormal in Chagas' disease.

Aneurysm↗