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Biomedical subjects

J M O'Brien

Publications and source records attributed to J M O'Brien.

At least 109 records · Page 6Linked to original sources
PubMed1986

Ectopic beta-human chorionic gonadotropin production by bladder urothelial neoplasia.

Endocrine manifestations are rarely observed in bladder urothelial neoplasia. To our knowledge, only 11 cases of choriocarcinoma have been reported in this site, and recently the production of beta-human chorionic gonadotropin has been demonstrated in these tumors by applying the immunoperoxidase technique. Of 104 transitional cell neoplasms of the bladder, we demonstrated by the indirect immunoperoxidase technique beta-human chorionic gonadotropin production in 12 neoplasms, 11 of which were grade 3 and 4 transitional cell carcinomas.

Aged↗
PubMed1985

Transitional cell carcinoma of the upper renal tract in rubber workers.

We report two patients where transitional cell carcinoma of the upper urinary tract developed after occupational exposure to known carcinogens, in the rubber industry. Although carcinoma of the bladder is well recognized in this context, to our knowledge, this association has not been reported previously.

Carcinoma, Transitional Cell↗
PubMed1985

Identification of a trans-dominant mutation affecting proline dehydrogenase in Escherichia coli.

L-Proline dehydrogenase catalyzes the oxidation of L-proline to delta 1-pyrroline-5-carboxylate, a reaction that is an important step in the utilization of proline as a carbon or nitrogen source by bacteria. A mutant of Escherichia coli K-12 lacking L-leucyl-tRNA:protein transferase had been found previously to contain about five times as much proline dehydrogenase activity as its parent strain. This difference has now been shown to be due to the presence in the parent strain of a previously unrecognized mutation. This mutation, which has been designated put-4977, specifically affects proline dehydrogenase rather than proline uptake. Although proline dehydrogenase remains inducible by L-proline in strains carrying the mutation, there is a premature cessation of differential synthesis during induction that results in a lower specific activity. The mutation shows about 50% P1-mediated cotransduction with pyrC and is therefore located at about 22 min on the E. coli chromosome. Merodiploids containing a normal F' factor still exhibit decreased enzyme activity, indicating that the put-4977 mutation is trans-dominant. The mutation cannot be detected in present stocks of the transferase-deficient mutant, suggesting that this mutant is a revertant for put-4977.

Acyltransferases↗
PubMed1985

Idiopathic hydronephrosis. Light microscopic features and pathogenesis.

A histological study of surgical specimens of idiopathic hydronephrosis demonstrated an abnormal muscle arrangement at the ureteropelvic junction in 18 of 26 cases. We believe this abnormality to be the cause in these cases. At this junction, the muscle bundles, instead of displaying the normal interwoven (braided) pattern, are arranged into an outer circular and an inner longitudinal layer. This abnormal muscle arrangement can be attributed to local failure of the physiological uncoiling during growth and development.

Adolescent↗
PubMed1984

Spoken and signed naming of foods after receptive exclusion training in severe retardation.

Two low-functioning mentally retarded subjects learned to name food items after receptive exclusion training, conducted as follows: The subjects first learned to select a small number of foods in a two-choice matching-to-sample task. For one subject, the samples were dictated names; for the other, the samples were manual signs. They also learned to name these "known" foods, either orally or by signing. On exclusion trials, a known food was displayed with a new food whose corresponding name or sign had not yet been learned, and a novel sample (spoken or signed), corresponding to the new food, was presented. The subjects typically selected the new food immediately, apparently by "excluding" the food related to the known sample. If a known sample was presented, however, the subjects continued to select the known food correctly. Periodically during exclusion training with a number of new foods, the subjects were tested for production of food names or signs. With few exceptions, the subjects produced the food names without direct training, often after only a few receptive exclusion trials. The results suggest strategies for teaching simple receptive and expressive relations to severely mentally retarded individuals.

Adolescent↗
PubMed1984

Association of hydrogen metabolism with unitrophic or mixotrophic growth of Methanosarcina barkeri on carbon monoxide.

Methanosarcina barkeri was adapted to grow on carbon monoxide by sequential transfer of the culture in medium that contained CO (100% of culture headspace). These experiments document the ability of the organism to grow slowly (65-h doubling time) and to produce methane and CO2 either on CO as the sole carbon and energy source or by the simultaneous consumption of methanol and CO. During growth on CO as carbon and energy source, net hydrogen formation occurred when the CO partial pressure in the culture headspace was greater than 20% CO, but hydrogen was consumed when the CO concentration was below this value.

Carbon Monoxide↗
PubMed1982

5'-deoxypyridoxal interaction with dexamethasone receptor: a new probe for structure and function of steroid receptors.

5'-Deoxypyridoxal, a vitamin B-6 analogue, increased the rate of dissociation of [3H]dexamethasone from HeLa S3 cytoplasmic glucocorticoid receptor complexes in vitro. This effect was achieved at millimolar concentrations of 5'-deoxypyridoxal, suggesting a low-affinity interaction of 5'-deoxypyridoxal with receptor. Loss of [3H]dexamethasone-receptor binding in the presence of 5'-deoxypyridoxal was pH dependent, and a plot of Kdiss vs. pH fit a simple sigmoidal titration curve with an inflection point at pH 7.8, suggesting that deprotonation of a single functional group on 5'-deoxypyridoxal increases Kdiss. Loss of [3H]dexamethasone binding in the presence or absence of unlabeled steroid also increased with pH, but no inflection point occurred over the range of pH tested. A titration of 5'-deoxypyridoxal indicated a pK of 7.94 for the pyridinium proton, suggesting deprotonation of the pyridinium nitrogen may account for the pH dependence of Kdiss of dexamethasone from receptor. 5'-Deoxypyridoxal also caused a decrease in nuclear [3H]-dexamethasone-receptor binding when incubated with whole HeLa S3 cells at 37 degrees C. Furthermore, 5'-deoxypyridoxal was effective in reducing nuclear binding of dexamethasone when added either simultaneously with [3H]dexamethasone or after achievement of equilibrium of steroid with receptor. The reduction in nuclear [3H]dexamethasone binding is highly specific for 5'-deoxypyridoxal. Several analogues of this compound, including 5'-deoxypyridoxamine, were ineffective. In addition, this effect was reversible following removal of extracellular 5'-deoxypyridoxal. Under these conditions, 5'-deoxypyridoxal was competitive with dexamethasone for binding to nuclear receptor, with KI = 8.1 X 10(-6) M. Scatchard plot analysis of dexamethasone-receptor binding in the presence or absence of 5'-deoxypyridoxal was consistent with an apparent reduced affinity of [3H]dexamethasone for receptor, which again suggests competitive interaction or allosteric interaction mediated dissociation. Glucocorticoids are known to stimulate alkaline phosphatase activity within HeLa S3 cells. In whole cell incubations, 5'-deoxypyridoxal was effective in reducing the dexamethasone-induced increase in alkaline phosphatase activity by 60% under conditions in which cell viability and cell growth were not affected.

Alkaline Phosphatase↗