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Biomedical subjects

G Roberts

Publications and source records attributed to G Roberts.

At least 181 records · Page 10Linked to original sources
PubMed1982

Pharmacokinetics and metabolism of antipyrine (phenazone) after intravenous and oral administration.

To 12 healthy male volunteers, 6 smokers and 6 non-smokers, 10 mg/kg antipyrine (phenazone) was administered i.v. and p.o. in random order. Following i.v. administration, antipyrine kinetics could be described best by an open two-compartment model. Absolute bioavailability of an aqueous solution of antipyrine was on average 97%. Antipyrine half-life in smokers was significantly shorter (mean 9.7 h) as compared to non-smokers (mean 11.7 h). Smokers excreted significantly more 3-hydroxymethyl-antipyrine (17.2 +/- 2.4 vs. 14.2 +/- 1.9%) than non-smokers, and clearance to this metabolite was significantly increased in smokers. In addition, cumulative urinary excretion of 4-hydroxy-antipyrine, norantipyrine and 3-hydroxymethyl-antipyrine was on average higher in smokers (77.1 +/- 5.0%) as compared to non-smokers (69.5 +/- 10.8%). Thus, 3-hydroxymethyl-antipyrine formation is induced in smokers.

Administration, Oral↗
PubMed1981

Tumour thickness and histological type in malignant melanoma in New South Wales, Australia, 1970-76.

A detailed histopathological review was made of 408 cases randomly selected from all malignant melanomata diagnosed in New South Wales, Australia, during the period 1970 to 1976. The distribution of histological types in relation to age, sex and body site was similar to those reported elsewhere. Pigmentation was also related to the histological type of the lesion. Tumour thickness was found to be strongly correlated with mitotic activity, histological type, tumour shape and lymphocytic infiltration at the centre of the lesion. Tumour thickness was also assessed in relation to the physical characteristics of the patient (age, sex and site of primary lesion). Because of the prognostic importance of tumour thickness, this objective measurement is recommended in preference to the subjective assessment of levels of invasion, and a guide to the correspondence between these two measures of severity is suggested.

Adult↗
PubMed1980

Melanoma in new South Wales 1970-1976. Confirmation of increased incidence.

A random sample of 500 cases from a total 5611 cases collected from a survey of melanoma in New South Wales, Australia, has confirmed an incidence rise which is apparent across all degrees of severity and all histogenetic classes. It therefore can be stated that the apparent increasing incidence of melanoma in New South Wales is not due to diagnostic errors. Nor is it due to inadequate registration of early melanomas in the initial years of study. The present study concludes that the increased rate of reporting of melanoma by New South Wales pathology services represents a true rise in the incidence of melanoma in the State.

Adult↗
PubMed1980

Mechanism of stimulation of pinocytosis by trypan blue.

Trypan blue at 50 microgram/ml stimulates the pinocytic uptake of 125I-labelled PVP, but not of colloidal 198Au or formaldehyde-denatured 125I-labelled bovine serum albumin, by the 17.5-day rat visceral yolk sac incubated in vitro. Neither Trypan blue nor a combination of the dye with 125I-labelled PVP stimulated the rate of pinocytosis of liquid by the tissue. Trypan blue itself was shown to enter the yolk-sac cells by adsorptive pinocytosis. It is proposed that an interaction between Trypan blue and 125I-labelled PVP enables the latter substrate to enter the cells adsorptively by so-called 'piggy-back' pinocytosis.

Animals↗
PubMed1979

In vitro studies of gallstone dissolution using the scanning electron microscope.

Scanning electron microscope studies on cholesterol gallstones, which had been subjected to, but had not been completely dissolved by, chenodeoxycholate and deoxycholate salts, have indicated the presence of an insoluble organic matrix, probably a mucopolysaccharide. Solution of a gallstone in vitro is enhanced by the addition of heparin which dissolved this matrix, thus allowing complete dissolution of cholesterol in a gallstone.

Chenodeoxycholic Acid↗
PubMed1978

Black pigment stone in a male child aged two years and seven months.

A case of cholelithiasis is reported occurring in a boy aged two years and seven months. The patient presented with biliary colic, and cholecystectomy was performed. Detailed analysis of the stone, including electron-probe studies, showed it to be an example of a polybilirubinate stone, containing also calcium, carbonate, and phosphate, with some sulphur, sodium, and magnesium. There were also traces of chlorine, aluminium, copper, nickel, and manganese.

Child, Preschool↗
PubMed1978

Raised alpha-fetoprotein levels in amniotic fluid and maternal serum associated with distension of the fetal bladder caused by absence of urethra.

Raised alpha-fetoprotein concentrations were found at 29 and 30 weeks' gestation in the amniotic fluid and maternal serum of a woman who presented in her seventh pregnancy with apparent polyhydramnios. The fetus had multiple abnormalities including gross distension of the bladder resulting from absence of the urethra, intestinal artresia, and a congenital heart defect.

Abnormalities, Multiple↗
PubMed1977

Trypan blue: identification and teratogenic and oncogenic activities of its coloured constituents.

Three coloured substances frequently present as contaminants in commercial samples of trypan blue have been identified as those monoazo dyes in which 4-amino-3,3'-dimethyl-biphenyl, 4-amino-3,3'-dimethyl-4'-hydroxy-biphenyl or omicroc-tolidine are coupled to H-acid. These dyes have been synthesized and, together with purified samples of trypan blue, tested for teratogenic activity in mice and oncogenic activity in rats. Unpurified trypan blue was both teratogenic and oncogenic; purified trypan blue, was teratogenic but only weakly oncogenic; the monoazo dyes possessed neither activity. It is concluded that the main blue component of trypan blue is the teratogenic principle and that some as yet unidentified component of the purple fraction either is the main oncogenic principle or potentiates the action of the blue component.

Animals↗
PubMed1977

Chromosomal damage induced by some ergot derivatives in vitro.

Three ergot derivatives, dihydroergotoxine, ergotamine and methysergide, were tested for their ability to induce chromosomal damage in human lymphocytes in culture. The aberration frequency was significantly increased after treatment of the cells with 0.1 microng/ml, 0.25 microng/ml and 0.5 microng/ml of each drug. However the degree of damage was considerably less than that produced by 0.1 mg/ml to 0.5 mg/ml of caffeine, which was used as a positive control and is a known mutagen in this test-system.

Caffeine↗
PubMed1976

Inhibition of pinocytosis in rat yolk sac by trypan blue.

Day 17.5 yolk sacs from rats injected with partially denatured 125I-labeled bovine serum albumin (I-BSA) were cultured in vitro by a raft technique. The rates of release of [125I]iodotyrosine were similar in control yolk sacs and in yolk sacs from rats preinjected with trypan blue. Day 17.5 rat yolk sacs were also cultured in medium containing I-BSA. Following pinocytic uptake the substrate was degraded intracellularly and [135I]iodotyrosine released into the medium. Trypan blue, when present in the medium in concentrations above 100 mug/ml, inhibited pinocytosis of I-BSA and so decreased the rate of [125I]iodotyrosine production. Trypan blue similarly decreased the rate of pinocytic uptake of 125I-labeled polyvinylpyrrolidone. Pinocytic uptake of macromolecules was not decreased in yolk sacs from rats pretreated with trypan blue. The relevance of these results to the mechanism of teratogenic action of trypan blue is discussed. It is proposed that if trypan blue in teratogenic doses similarly inhibits pinocytosis by the yolk sac during the organogenetic period teratogenesis might result from a transient interruption in the flow of metabolites through the yolk sac to the embryo.

Animals↗