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Biomedical subjects

G S Shephard

Publications and source records attributed to G S Shephard.

At least 55 records · Page 3Linked to original sources
PubMed1992

Fate of a single dose of the 14C-labelled mycotoxin, fumonisin B1, in rats.

The fate of the mycotoxin, fumonisin B1, (FB1) dosed to rats by i.p. injection and by gavage was traced using 14C-labelled FB1. Twenty-four hours after i.p. injection, 66% of the radioactivity was recovered in faeces, 32% in urine, 1% in liver and trace amounts (less than 1%) in kidney and red blood cells. When dosed by gavage, all (101%) radioactivity was recovered in faeces and trace amounts were found in urine, liver, kidney and red blood cells. The bulk of the radioactivity recovered was unmetabolized FB1.

Animals↗
PubMed1992

Initial studies on the toxicokinetics of fumonisin B1 in rats.

Fumonisin B1 (FB1), the major compound in the fumonisin group of secondary metabolites of Fusarium moniliforme Sheldon, is associated with some human and animal diseases. After intraperitoneal dosing to rats (7.5 mg/kg), FB1 was rapidly absorbed and reached a maximum concentration in plasma within 20 min after injection. Thereafter, it underwent rapid removal from plasma, displaying a mono-exponential elimination phase that fitted a one-compartment model with a half-life of 18 min. Collection of 24- and 48-hr urine samples indicated that only 16% of the applied dose was eliminated unmetabolized in urine, all within the first 24-hr period following dosing. In contrast to this, a similar dose of FB1 given by gavage resulted in the recovery of only 0.4% of the FB1 in urine.

Administration, Oral↗
PubMed1991

Reversed-phase high-performance liquid chromatography of tenuazonic acid and related tetramic acids.

A reversed-phase high-performance liquid chromatographic system for the determination of the fungal toxin, tenuazonic acid, (5S,8S)-3-acetyl-5-sec.-butyltetramic acid, is described. The system utilizes a column packed with deactivated end-capped C18 silica with a high carbon load to overcome the problem of poor chromatographic performance of this beta-diketone on reversed-phase liquid chromatography which previously necessitated the use of anion-exchange, ligand-exchange or ion-pairing methods. The reversed-phase system allows the separation of tenuazonic acid from its (5R,8S)-diastereomer, allo-tenuazonic acid and was applied to the detection of tenuazonic acid in cultures of Alternaria alternata and Phoma sorghina. By means of diode-array ultraviolet detection, (5S)-3-acetyl-5-isopropyltetramic acid was observed in extracts of culture material. This metabolite was purified using the analytical reversed-phase system and was identified by 1H and 13C nuclear magnetic resonance spectroscopy.

Alternaria↗
PubMed1991

Survey of fumonisin production by Fusarium species.

Fumonisins B1 (FB1) and B2 (FB2), two structurally related mycotoxins with cancer-promoting activity, were recently isolated from corn cultures of Fusarium moniliforme MRC 826. These toxins have been reported to be produced also by isolates of F. proliferatum. Contamination of foods and feeds by F. moniliforme has been associated with human esophageal cancer risk, and FB1 has been shown to be the causative agent of the neurotoxic disease leukoencephalomalacia in horses. Because of the toxicological importance of the fumonisins, the potential to produce FB1 and FB2 was determined in a study of 40 toxic Fusarium isolates representing 27 taxa in 9 of the 12 sections of Fusarium, as well as two recently described species not yet classified into sections. With the exception of one isolate of F. nygamai, fumonisin production was restricted to isolates of F. moniliforme and F. proliferatum, in the section Liseola. The F. nygamai isolate produced 605 micrograms of FB1 g-1 and 530 micrograms of FB2 g-1, and the identity of the toxins was confirmed by capillary gas chromatography-mass spectrometry. This is the first report of the production of the fumonisins by F. nygamai.

Carcinogens, Environmental↗
PubMed1987

Plasma vitamin A, E, C and B6 levels in myocardial infarction.

Vitamin A, E, C and B6 status was studied in 30 patients with myocardial infarction and in 19 age- and sex-matched patients after elective surgery or trauma. Plasma levels of the four vitamins studied were low, remained low or decreased transiently in both groups of patients during the acute catabolic response phase, and began to return to normal after the third day from the start of the catabolic response. These changes in plasma levels are therefore neither of any special pathophysiological importance in nor specific to myocardial infarction.

Adult↗
PubMed1987

The effect of pyridoxine supplementation on plasma pyridoxal-5'-phosphate levels in children with the nephrotic syndrome.

Nineteen children with low plasma pyridoxal-5'-phosphate (PLP) levels in the nephrotic syndrome due to a variety of histological entities were successfully supplemented with oral pyridoxine hydrochloride. A dose of approximately 2 mg/kg/day of pyridoxine hydrochloride was found to effect adequate plasma PLP levels in most cases. A significant (p less than 0.001) positive correlation (r = 0.83) was found between plasma albumin and PLP levels prior to supplementation and after supplementation both in relapse and remission. Although vitamin B6 repletion led to no demonstrable effect on the clinical course of the syndrome, in view of the possible role which vitamin B6 deficiency may play in defective immune response and thromboembolic phenomena, both being known complications of the nephrotic syndrome, the administration of vitamin B6 supplements is recommended in the active disease state.

Administration, Oral↗
PubMed1986

Determination of plasma amino acids by gas chromatography.

A complete methodology, incorporating a novel clean-up technique, for quantitative determination of amino acids in plasma by gas chromatography is described. Glucose, a component causing major analytical interference, is removed by an enzymic reaction included in the pre-chromatographic clean-up. The procedure for derivatisation of amino acid standards is shown to be reproducible down to a level of 2.5 micrograms for each amino acid, relative standard deviations for all amino acids except arginine and histidine being 3% or lower. For the entire procedure applied to plasma, relative standard deviations for most amino acids are below 5% with recoveries ranging from 90 to 120%. Normal values, obtained using eighteen plasma samples, are in reasonable agreement with published data. Plasma amino acid values were determined simultaneously by gas chromatographic and ion-exchange chromatographic techniques. Statistical evaluation shows there to be no significant difference between corresponding values for eleven amino acids. Values for tyrosine, histidine and particularly phenylalanine show significant differences (p less than 0.001).

Adenosine Triphosphate↗
PubMed1986

Biochemical vitamin E deficiency in chronic pancreatitis.

In order to study the frequency of biochemical vitamin E deficiency in chronic alcohol-induced pancreatitis, we measured plasma vitamin E and total blood lipids in 44 patients with chronic pancreatitis and 83 control subjects (44 normal controls; 39 Crohn's disease controls). Mean plasma vitamin E and mean ratio vitamin E/total blood lipids, a more sensitive indicator of vitamin E status, were significantly lower in chronic pancreatitis when compared with either control group. A low vitamin E/total lipids ratio was found in 75% of patients with pancreatitis. Within the chronic pancreatitis group, mean plasma vitamin E and the ratio vitamin E to total lipids were significantly lower in those with steatorrhoea (23 patients--pancreatic steatorrhoea subgroup) than in those without (21 patients--pancreatic non-steatorrhoea subgroup). 91% of the pancreatic steatorrhoea subgroup had a low vitamin E/total lipids ratio. However, patients without pancreatic steatorrhoea also had significantly lower levels of plasma vitamin E and the ratio vitamin E/total lipids when compared to controls. We conclude that biochemical vitamin E deficiency is common in chronic alcohol-induced pancreatitis, particularly in patients with steatorrhoea, and that factors other than fat malabsorption may be responsible for vitamin E deficiency in pancreatic non-steatorrhoea.

Adolescent↗