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Biomedical subjects

S M Baker

Publications and source records attributed to S M Baker.

50 records · Page 3Linked to original sources
PubMed1986

Follow-up evaluation of horses after neonatal intensive care.

A follow-up study was conducted on 131 foals that were less than 7 days old when admitted to the University of Florida Veterinary Medical Teaching Hospital between 1981 and 1983. Of the 71 foals (54%) that survived to be discharged, 39 (55%) were alive at follow-up evaluation, 19 (27%) could not be located, and 13 (18%) had died. The owners of surviving foals were sent questionnaires and 72% responded. The horses were visited and examined, if geographically possible, and an age-matched stablemate or a sibling also was evaluated and used as a control. Thirteen foals (10% of total admitted) died 1 day to 2 years after discharge. Four (8%) died from suspected sequelae of their neonatal illness. Three other foals appeared stunted as yearlings, but by 2 years of age equaled or passed their stablemates and/or siblings in physical development. The owners' estimated value of the survivors averaged +29,812. The actual selling price of horses that went through sales ranged from +7,000 to +210,000. Most of the horses became useful, athletic adults; several have won major stakes races. All living foals appeared unaffected by the physiologic disorders and treatments they encountered as neonates and compared favorably with stablemates and siblings.

Animals↗
PubMed1986

Hemophiliac immunodeficiency: influence of exposure to factor VIII concentrate, LAV/HTLV-III, and herpesviruses.

The relationship between hemophiliac immunodeficiency and exposures to factor VIII concentrate, LAV/HTLV-III retrovirus, and infection with Epstein-Barr virus and cytomegalovirus was examined. Exposure to factor VIII concentrate was significantly correlated with decreased percentages of T helper/inducer cells, decreased T helper/suppressor cell ratios, and decreased proliferative responses to plant mitogens. LAV/HTLV-III seropositivity was the primary predictor of increased percentages of HLA-DR-bearing mononuclear cells and decreased proliferative responses to pokeweed mitogen. Epstein-Barr virus and cytomegalovirus infections acted in a synergistic manner with LAV/HTLV-III to produce immunoregulatory defects. Increased percentages of T suppressor cells and decreased delayed cutaneous hypersensitivity skin test responses were observed in LAV/HTLV-III seropositive hemophiliacs infected with Epstein-Barr or cytomegalovirus. We conclude that hemophiliacs receiving commercial factor VIII concentrate experience several stepwise incremental insults to the immune system: alloantigens in factor VIII concentrate, LAV/HTLV-III infections, and herpesvirus infections.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Magnesium deficiency in the pathogenesis of mitral valve prolapse.

Idiopathic mitral valve prolapse (MVP) is the commonest valvular disorder in industrialized nations. It is predominantly a familial condition, showing Mendelian dominance with delayed and variable penetrance. Although hyperkinesis and hypertrophy of the left ventricle have been described in MVP, its histopathology, somatic morphology and genetics support the leading theory that MVP results from a hereditary disorder of connective tissue. Latent tetany (LT) due to chronic Mg deficit (Mg-D) occurs in over 85% of MVP cases; MVP complicates 26% of LT. Mg-D can explain many clinical features of the MVP syndrome which are not easily explained by its genetics. Mg-D hinders the mechanism by which fibroblasts degrade defective collagen, increases circulating catecholamines, predisposes to cardiac arrhythmias, thromboembolic phenomena and dysregulation of the immune and autonomic nervous systems. Mg therapy provides relief of MVP symptoms.

Alprostadil↗
PubMed1985

Correlation of the octanol/water partition coefficient with clearance half-times of intratracheally instilled aromatic hydrocarbons in rats.

Studies on the lung retention of polycyclic aromatic hydrocarbons (PAH) after inhalation have indicated that, in general, the PAH are rapidly cleared from the respiratory tract. Clearance of the PAH from the lungs is best described as bi-phasic, with the long-term component of the clearance curve having a half-time of greater than 24 h. The purpose of this study was to determine whether a relationship exists between the lipophilicity (as measured by the octanol/water partition coefficient, P) of various PAH and the short-term and long-term clearance half-times of PAH in rat lungs. Female F344/Crl rats were administered intratracheally 1 nmol of 14C-labelled anthracene (AN), benz[a]anthracene (BA), 1-nitropyrene (NP), 6-nitrobenzo[a]pyrene (6-NBP), or dibenzo[c,g]carbazole (DBC). At various times after instillation rats were sacrificed and the amount of 14C remaining in the lungs was determined. Octanol/water partition coefficients were experimentally determined for each of the PAH used. Clearance of 14C from rat lungs following instillation of the different PAH was biphasic. In all cases, greater than 85% of the initial dose instilled was cleared with a half-time of less than 1 h. The half-times for clearance of the residual 14C (1-15% of the dose) were 26, 30, 36, 53 and 63 h for AN, NP, 6-NBP, BA and DBC, respectively. The log of the octanol/water partition coefficients for the different PAH examined ranged from 4.1 (AN) to 6.05 (DBC). Plots of the octanol/water coefficients vs. the long-term clearance half-time for the PAH indicated a linear correlation (p less than 0.001; r2 = 0.96). The results from this study indicate that the greater the lipophilicity of the PAH, the slower the long-term clearance of a small fraction (1-15%) of PAH from rat lungs. These data suggest that predictions of long-term lung clearance can be made for PAH with log octanol/water partition coefficients between 4 and 6.

Animals↗
PubMed1984

Expression of the Saccharomyces cerevisiae GAL7 gene on autonomous plasmids.

We used a combination of cloned DNA fragments encoding the GAL7 gene, yeast plasmid vectors, and chromosomal gal7 deletions to characterize the in vivo transcription of the GAL7 gene on autonomously replicating plasmids. Our results demonstrated that a plasmid-borne 3.1-kilobase DNA fragment containing the GAL7 gene provides sufficient information to mimic the regulated expression of the chromosomal location. Normal expression of GAL7 could occur in the absence of DNA encoding the functional genes of the GAL cluster region and was not altered when the gene was adjacent to other plasmid elements such as autonomously replicating sequences or centromeres. The chromosomal and single-copy centromeric plasmid locations of GAL7 were indistinguishable in their response to growth conditions (induction by galactose, repression by glucose) and positive and negative regulatory factors (GAL4 and GAL80). Increasing the gene dosage to more than 200 copies per cell resulted in constitutive expression of the GAL7 mRNA; fully induced mRNA levels were increased more than 10-fold at these high gene dosages. When cells were shifted from noninducing to inducing conditions, the initial time of appearance and the rate of accumulation of GAL7 mRNA were altered in cell populations containing multiple GAL7 genes. The induction kinetics and final accumulation of the chromosomal GAL10 mRNA were also affected by the presence of multiple copies of the GAL7 gene; these results are consistent with a model involving limiting amounts of regulatory factors.

Cloning, Molecular↗
PubMed1983

X-linked lymphoproliferative syndrome. Natural history of the immunodeficiency.

The X-linked lymphoproliferative syndrome is characterized by immunodeficiency to Epstein-Barr virus (EBV) manifested by severe or fatal infectious mononucleosis and acquired immunodeficiency. We studied immune responses in six males of a well-characterized kindred with the X-linked lymphoproliferative syndrome. Two males were studied before and during acute fatal EBV infection. Both individuals demonstrated normal cellular and humoral immunity before EBV infection. During acute EBV infection, both individuals developed vigorous cytotoxic cellular responses against EBV-infected and -uninfected target cells. Anomalous killer and natural killer T cell activity was demonstrated against a variety of lymphoid cell lines, autologous fibroblasts and autologous hepatocytes. Effector cells responsible for anomalous killing reacted with a pan-T cell monoclonal antibody, and belonged to the OKT.8 T cell subset. Death in each case was caused by liver failure, but one patient developed extensive liver necrosis, whereas the other developed a massive infiltration of the liver with EBV-infected immunoblasts after aggressive immunosuppressive therapy. Immunological studies were performed on four males who had survived EBV infection years previously. They demonstrated global cellular immune defects with deficiencies of lymphocyte proliferative responses to mitogens and antigens, humoral immune deficiencies, abnormalities of regulatory T cell subsets and deficient natural killer cell activity. We propose that an aberrant immune response triggered by acute EBV infection results in unregulated anomalous killer and natural killer cell activity against EBV infected and uninfected cells. These studies suggest that global immune defects appearing in males with X-linked lymphoproliferative syndrome who survive EBV infection are epiphenomenon.

Adolescent↗
PubMed1977

The mental health of children in an HMO program.

Collaboration between pediatricians and mental health clinicians in an HMO has provided a useful method of identifying and caring for the usual spectrum of developmental and situational disturbances in children and the associated parent-child conflicts. A social worker is included in the primary-care team in pediatrics; other mental health resources are available when indicated. In 1974, 5.7% of total visits and 8.9% of all children under 19 years of age were noted to have emotional problems. A follow-up study carried out early in 1976 disclosed that most of the observed emotional problems were resolved or quiescent.

Child↗
PubMedDate not supplied

Is vernix caseosa a protective material to the newborn? A biochemical approach.

Twenty random samples of vernix caseosa were collected from immediately born neonates, in Jamahiriya Hospital, Benghazi. Biochemical studies of these samples revealed presence of lipids (62.5%), proteins (36%) and carbohydrate (1.5%). Also we could observe inhibition of staph. aureus and klebsiella growth on nutrient agar by this vernix. This observation could be explained either by its higher asparagine content or by its elevated lipid component. In addition tripalmitin was found to be the major lipid constituent, responsible for its hydrophobic property. So we recommend leaving this vernix layer on newborn skin until spontaneous drying.

Humans↗
PubMedDate not supplied

Magnesium in primary care and preventive medicine: clinical correlation of magnesium loading studies.

Diagnostic categories that are useful for describing patients with acute or organ failure disease are generally less useful labels for primary care and preventive medicine patients whose conditions are better described by signs and symptoms. Symptoms may be clues to ill health but are not often criteria for a major diagnostic labeling. In my practice I have used a computer-based medical record system that permits portrayal and comparison of symptom data to correlate varying degrees of retention of an intramuscular magnesium-loading study (IMMLS) with symptom patterns in 172 patients. The group of patients who show a paradoxical excretion of more Mg than they were given in the IMMLS are a distinctive group with lower blood pressures and significantly fewer digestive and skin symptoms, fewer symptoms of inflammation but more emotional symptoms than those with normal Mg excretion. The group who retained > 49% of the load had higher blood pressures and significantly fewer symptoms of inflammation of the skin and of the reproductive tract.

Adolescent↗