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Biomedical subjects

D Parker

Publications and source records attributed to D Parker.

At least 307 records · Page 17Linked to original sources
PubMed1978

Comparison of oral and intravenous methylphenidate.

Oral methylphenidate (1.0 mg/kg) and intravenous methylphenidate (0.5 mg/kg) were compared as to their ability to increase behavioral activation, pulse, blood pressure, and serum growth hormone. Intravenous methylphenidate was considerably more effective than oral methylphenidate in activating behavior and in increasing pulse and blood pressure. Although oral methylphenidate appeared to increase behavioral activation, this effect was not statistically significant.

Administration, Oral↗
PubMed1978

Drugs for myeloma.

Explore the source record for details and available documents.

Cyclophosphamide↗
PubMed1978

Studies of the effects of ultraviolet radiation on the structural integrities of ribosomal RNA components of the Escherichia coli 50S ribosomal subunit.

The effects of 254-nm radiation on the structural integrities of free and 50S ribosome-bound 5S and 23S ribosomal ribonucleic acids (rRNA) have been elucidated. Irradiation of aqueous solutions of Escherichia coli 50S ribosomes with 253.7-nm radiation results in the formation of single-strand breaks in double-stranded regions of the 23S rRNA component, but not in rRNA chain scission, and destabilization of the secondary structure of the 23S rRNA toward denaturation. The minimum doses of 253.7-nm radiation required for the first detection of the two effects are 7 x 10(19) quanta for the production of single-strand breaks in double-stranded regions of the 23S rRNA, and less than 2.3 x 10(19) quanta for destabilization of the 23S rRNA secondary structure. Free 23S rRNA is resistant toward photoinduced chain breakage at doses of 253.7-nm radiation up to at least 2.3 x 10(20) and is much less sensitive toward destabilization of secondary structure than ribosome-bound 23S rRNA toward chain breakage, 50S ribosome-bound 5S rRNA is resistant toward chain breakage at doses of 253.7-nm radiation up to at least 2.3 x 10(20) quanta. Ribosome-bound 5S and 23S rRNA are also not photosensitive toward intermolecular 5S/23S rRNA crosslinkage.

Escherichia coli↗
PubMed1978

Methylphenidate and serum prolactin in man.

Methylphenidate induces psychostimulation and increases cardiovascular parameters, and its psychostimulant effects have been proposed to occur via a dopaminergic mechanism. The effect of methylphenidate on serum prolactin was utilized as a method of evaluating methylphenidate's central dopamimergic effects. Methylphenidate was not found to exhibit a consistent effect on serum prolactin. Thus, its effect on serum prolactin does not parallel its behavioral activating properties, suggesting that such activation may not involve dopamine. Possibly, norepinephrine or other noncatecholaminergic neurotransmitters are involved in methylphenidate-induced behavioral activation.

Adult↗
PubMed1978

The effect of methylphenidate on serum growth hormone: influence of antipsychotic drugs and diagnosis.

Intravenously administered methylphenidate, 0.5 mg/kg, causes a consistent rise in human serum growth hormone level, with peak values usually occurring 30 minutes after infusion. This rise is attenuated in patients receiving various antipsychotic medications administered on a long-term basis and is decreased in schizophrenic and drug-dependent patients. Methylphenidate causes increases in talkativeness, blood pressure, and pulse that generally parallel increases in serum growth hormone level. However, in contrast to the methylphenidate-induced rise in serum growth hormone level, methylphenidate-induced changes in cardiovascular variables and talkativeness are not altered by antipsychotic medications or diagnostic classification.

Adjustment Disorders↗
PubMed1978

Ultrastructural observations on epithelioid cell granulomas induced by zirconium in the guinea-pig.

An ultrastructural study has been made of the allergic-type nodular granulomas that can be induced in guinea-pigs sensitised to sodium zirconium lactate. Lesions taken at the peak of granuloma development 7 days after skin testing contained epithelioid cells which could be recognised particularly by their content of rough endoplasmic reticulum, fimbriated cell membrane and typical nuclear appearance. Multinucleate giant cells were also seen. These cells were characterised by their large number of lysosome-like dense bodies and phagocytic structures. Both epithelioid cells and multinucleate giant cells were similar to those described in zirconium granulomas in man. However, these cells differed in a number of respects from similar cells observed in human sarcoidosis. A constant feature of the guinea-pig lesions was the presence of large numbers of apparently active fibroblasts.

Animals↗
PubMed1978

The effects of some aluminium and zirconium compounds on guinea-pig peritoneal macrophages and skin fibroblasts in culture.

The damaging effects of some industrially important Aluminium and Zirconium compounds on guinea-pig macrophages and skin fibroblasts have been investigated. Cell death was measured by the release of lactate dehydrogenase activity. The haemolytic properties of these compounds has also been investigated. There is a correlation between the ability of these compounds to form granulomas after intradermal injection in the guinea-pig, their toxic effects on macrophages and fibroblasts and their haemolytic properties. A possible mechanism of toxicity of these compounds towards macrophages and fibroblasts is suggested.

Aluminum↗
PubMed1978

A transcutaneous PO2 electrode incorporating a thermal clearance local blood flow sensor.

Several possible methods for estimating and recording skin blood flow by thermal clearance are presented. The method chosen for trial with an O2 electrode was to thermoregulate an annular anode which covered the cathode, surrounding it like a heat shell, and to measure the cooling of the cathode by blood flow, by implanting a thermistor near the surface of the cathode. This device is far less affected by ambient temperature than is simple measurement of heating power in an uninsulated tcPO2 electrode.

Blood Gas Analysis↗