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Biomedical subjects

S R Wilson

Publications and source records attributed to S R Wilson.

At least 145 records · Page 8Linked to original sources
PubMed1987

Sacrococcygeal teratoma: prenatal diagnosis and management.

Although sacrococcygeal teratoma is a rare and potentially malignant tumor, 10 cases were documented during a 5-year period at the University of Toronto Perinatal Complex. Diagnosis was made in the six cases in which prenatal ultrasound examination was performed. One patient with twins elected to terminate the pregnancy at 19 weeks. In three of the cases diagnosed prenatally, serial ultrasound was performed. There was a 75% cesarean section rate. In all cases diagnosed prenatally, the large tumor size affected the mode of delivery. In the four cases without prenatal diagnosis, two infants were delivered vaginally, and two were delivered abdominally for obstetric reasons. There was one case of neonatal morbidity where tumor vascularity and rupture resulted in hypovolemic shock. All tumors were resected and found to be benign. A plan of management is recommended and, with appropriate obstetric and pediatric care, a good outcome can be anticipated in most cases.

Diseases in Twins↗
PubMed1986

The action of islet activating protein (pertussis toxin) on insulin's ability to inhibit adenylate cyclase and activate cyclic AMP phosphodiesterases in hepatocytes.

Treatment of hepatocytes with islet activating protein (pertussis toxin) from Bordetella pertussis blocked the ability of insulin to inhibit adenylate cyclase activity both in broken plasma membranes and in intact hepatocytes. Such treatment of intact hepatocytes with pertussis toxin did not prevent insulin from activating the peripheral plasma membrane cyclic AMP phosphodiesterase although it did inhibit the ability of insulin to activate the 'dense-vesicle' cyclic AMP phosphodiesterase. The ability of glucagon pretreatment of hepatocytes to block insulin's activation of the plasma membrane cyclic AMP phosphodiesterase was abolished in pertussis toxin-treated hepatocytes. It is suggested that the ability of insulin to manipulate cyclic AMP concentrations by inhibiting adenylate cyclase and activating the plasma membrane and 'dense-vesicle' cyclic AMP phosphodiesterases involves interactions with the guanine nucleotide regulatory protein system occurring in liver plasma membranes.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1986

Log-linear model analysis of allelic associations.

An approach is outlined for the analysis of nonrandom allelic associations in multilocus systems in a diploid population. The concept of composite link functions in generalised linear model analysis is used to handle the problem of incomplete identification of constituent gametes often encountered in genotypic data for two or more marker loci.

Alleles↗
PubMed1986

Log-linear models for linked loci.

A clarification is given of the difference between a multiplicative model (Haber, 1984, Biometrics 40, 189-198) and an additive model (Weir, 1979, Biometrics 35, 235-254) for association between genes at two loci. Although the parametrization of Haber contains both intergametic and intragametic linkage disequilibrium terms, there are problems in separating these terms when the two types of double heterozygote cannot be distinguished. An alternative formulation that contains the sum and product of these terms also contains measures of association between three or four genes at two loci, and a reexamination of data discussed by Haber shows that the inclusion of trigenic disequilibria can significantly improve the fit of the model.

Alleles↗
PubMed1985

Effect of P-450scc inhibitors on corticosterone production by rat adrenal cells.

Suspensions of rat adrenocortical cells produce corticosterone as the major glucocorticoid. Cholesterol side-chain cleavage, the initial and rate-limiting step in the glucocorticoid biosynthetic pathway, is catalyzed by P-450scc. We have examined the effect of a variety of P-450scc inhibitors on corticosterone production by isolated rat adrenocortical cells. These inhibitors include reversible, noncovalently interacting inhibitors as well as mechanism-based inhibitors which irreversibly inactivate P-450scc in vitro. (20S)-22-nor-22-thiacholesterol and (22R)-22-aminocholesterol cause 50% inhibition of corticosterone production at 4 microM and 30 nM, respectively. Inhibition by these compounds was essentially not time-dependent. (20R)-20-(1-hexynyl)-pregn-5-en-3 beta, 20-diol and (20R)-20-(1,5-hexdiynyl)-pregn-5-en-3 beta, 20-diol at 10 microM inhibited corticosterone production in a time-dependent manner, resulting in 30% inhibition of corticosterone production during a 100-min incubation. (20S)-20-(2-trimethylsilyl ethyl)-pregn-5-en-3 beta, 20-diol inhibited in a strongly time-dependent manner. At 10 microM this compound irreversibly inhibited more than 90% of the side-chain cleavage capacity of the cell during a 40-min incubation. Cells treated with this steroid did not regain their capacity for side-chain cleavage after removal of free steroid. None of the inhibitors described above inhibited production of corticosterone by cells supplied with pregnenolone, the product of the P-450scc reaction. We suggest that the only significant effect of these compounds under these conditions is inhibition of the side-chain cleavage enzyme.

Adrenal Cortex↗
PubMed1985

Suprapubic sonographic detection of prostate carcinoma.

Between January 1 and March 31, 1983, 103 patients scheduled for prostatic surgery were blindly evaluated preoperatively by suprapubic real time sonography. Prospectively, the sensitivity was 72.7%, specificity 72.2%, predictive value of positive test 51.6% and predictive value of negative 86.7% for the detection of prostatic carcinoma. Retrospective analysis increased the sensitivity to 86% and when clinical information was utilized, only one carcinoma escaped detection. Unfortunately, both prostatic inflammation and occasionally benign prostatic hypertrophy may simulate carcinoma sonographically, thus producing a significant number of false positives. No ultrasonically detectable characteristics could be found which unequivocally separate carcinomas from inflammation and hypertrophy. For this reason routine suprapubic screening does not seem warranted.

Carcinoma↗
PubMed1985

Rapid in vitro replication of group B streptococcus in term human amniotic fluid.

4-hour in vitro growth curves of a type III group B streptococcus (GBS) and Escherichia coli were examined in sterile term human amniotic fluid specimens. Both bacterial strains proliferated despite ratios of phosphate to elemental zinc in the range reportedly inhibitory for E. coli. After 4 h of incubation, despite comparable inocula, GBS numbers exceeded those of E. coli by 10-fold. The strikingly rapid growth of some GBS strains in amniotic fluid may represent yet another factor responsible for perinatal GBS infection of the human neonate.

Amniotic Fluid↗
PubMed1985

Therapeutic processes in a Yoga Ashram.

Although communal and new religious groups are said to provide quasi-therapeutic experiences for relatively healthy individuals in our society, there is little information about how this occurs. This study examines the lifestyle and social structure of a yoga ashram and describes how they facilitate processes where residents learn to release and prevent stress in their lives.

Adaptation, Psychological↗
PubMed1984

An assessment of the ability of insulin-stimulated cyclic AMP phosphodiesterase to decrease hepatocyte intracellular cyclic AMP concentrations.

Treatment of hepatocytes with either NH4Cl (10mM) or fructose (10mM) blocks insulin's activation of the 'dense-vesicle' cyclic AMP phosphodiesterase. The ability of insulin (10 nM) to decrease intracellular cyclic AMP concentrations raised by glucagon (10 nM) was unaffected by pre-treatment with either NH4Cl (10 mM) or fructose (10 mM). It is concluded that the 'dense-vesicle' enzyme does not play a significant role in this action of insulin and that as yet unidentified cyclic AMP phosphodiesterase(s) must be activated by insulin. Treatment of hepatocytes with either NH4Cl or fructose appeared to increase, reversibly, cyclic AMP phosphodiesterase activity. When N6-(phenylisopropyl)adenosine was used to prevent glucagon from blocking insulin's activation of the plasma-membrane cyclic AMP phosphodiesterase activity, insulin's ability to decrease intracellular cyclic AMP concentrations in glucagon-treated hepatocytes was increased markedly. Insulin's activation of the plasma-membrane cyclic AMP phosphodiesterase activity can exert a potent effect in decreasing intracellular cyclic AMP concentrations elevated by glucagon.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1984

On the possible role of biliverdin stimulation of cyclic AMP levels as a trigger for liver regeneration in the rat.

Contrary to a recent report by Okazaki et al. (Biochem. biophys. Res. Commun., 1978, 81, 512-520) we show that high concentrations of biliverdin (100 mg/kg, i.p.) slightly reduce the mitotic rate in rat liver. Adenylate cyclase and both the "high Km" and "low Km" phosphodiesterase of rat liver plasma membranes are inhibited by high concentrations of biliverdin. Biliverdin has no effect on cyclic AMP production in isolated hepatocytes. An intracellular binding protein (glutathione-S-transferase B) is shown to bind biliverdin providing a mechanism for maintaining a low free intracellular concentration of the tetrapyrrole analogous to that of albumin in plasma. In conclusion, these results are not consistent with a role for biliverdin in stimulating liver regeneration in the rat via a mechanism involving elevated cyclic AMP levels.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1984

Intravenous immunoglobulin in neonatal group B streptococcal disease. Pharmacokinetic and safety studies in monkeys and humans.

Numerous studies have suggested that opsonic antibody is important in neonatal immunity to group B streptococci. Immunoglobulin G is primarily transferred from the mother to the fetus across the placenta in the last few weeks of pregnancy. Premature babies may, therefore, not acquire sufficient opsonic antibody to protect them from infection with group B streptococci. Although maternal immunization may provide adequate maternal opsonic antibody, premature infants with antibody deficiency may remain susceptible to infection. Intravenous immunoglobulin administered to term pregnant rhesus monkeys did not provide reliable levels of serum opsonic activity to group B streptococci in their offspring. Pharmacokinetic and safety studies were also performed in human neonates. Significant elevations in group B streptococcal-specific IgG did occur in human neonates given 500 mg/kg intravenous immunoglobulin and the infusions appeared safe and well tolerated. The availability of intravenous immunoglobulin with functional activity against group B streptococci may provide a rapid and effective method of delivering opsonic antibody to neonates.

Adult↗