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Biomedical subjects

D Perrett

Publications and source records attributed to D Perrett.

140 records · Page 8Linked to original sources
PubMed1972

Dipeptide absorption in man.

A quantitative perfusion method has been used to study intestinal absorption of two dipeptides-glycyl-glycine and glycyl-l-alanine-in normal subjects. In each case, the constituent amino acids were absorbed faster when presented as dipeptides than as free amino acids, suggesting intact dipeptide transport. During absorption constituent amino acids were measured within the lumen and it is suggested that these represent amino acids which have diffused back to the lumen after absorption as dipeptide. Portal blood analyses during absorption of a third dipeptide, glycyl-l-lysine, have shown that this dipeptide, known to be transported intact from the intestinal lumen, is hydrolysed to its constitutent amino acids before it reaches portal venous blood.

Adult↗
PubMed1970

Dipeptide absorption in cystinuria.

Absorption of a dipeptide and its constituent amino-acids has been studied by a perfusion technique in a patient with cystinuria and in a normal subject. Though the cystinuric patient was unable to absorb the dibasic amino-acid lysine in its free form, the dipeptide glycyl-L-lysine was well absorbed. Both free lysine and glycyl-L-lysine were well absorbed in the normal subject.This finding suggests that the reason that clinical malnutrition does not occur in cystinuria, despite defective intestinal absorption and heavy renal loss of dibasic amino-acids and cystine, is that these amino-acids can be absorbed in the form of oligopeptides.

Cystinuria↗
PubMedDate not supplied

Improved resolution of tryptic digest fragments from haemoglobin variants using phytic acid in free zone capillary electrophoresis.

Capillary electrophoresis can be applied to the rapid characterization of tryptic digests of proteins. The addition of phytic acid to the separation buffer was found to improve resolution considerably when the technique was applied to differentiate between tryptic digests derived from variant haemoglobins. Moreover, analysis time was of the order of 15 min, which is considerably shorter than that obtained using gradient reversed-phase high-performance liquid chromatography or two-dimensional paper chromatography-electrophoresis.

Animals↗
PubMedDate not supplied

Determination of 5-hydroxytryptamine, 5-hydroxyindoleacetic acid and tryptophan in plasma and urine by HPLC with fluorimetric detection.

Using native fluorescence detection, 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA) and tryptophan were resolved from themselves and other naturally occurring compounds using reversed-phase HPLC within 5 min. Deproteinated platelet-poor plasma (PPP) and crude diluted urine were injected directly into the chromatograph. Careful selection of the HPLC column is important and various octadecyl silica (ODS) and base deactivated silic (BDS) columns were evaluated. Pre-treatment of an ODS column with tetrabutylammonium ions gave good selectivity. Between pH 5 and 6 the compounds were well resolved from each other. The limit of quantitative detection of 5-HT and 5-HIAA was 3.5 nmol/L. The overall chromatogram obtained using native fluorescence is cleaner than that obtained with the more commonly employed electrochemical (EC) systems although the chromatography is effectively the same. For analysis of 5-HT in plasma, collection in EDTA was more efficient than lithium heparin. Plasma 5-HT in healthy volunteers was mean 61 (SD = +/- 73) nmol/L, n = 20; urine 5-HIAA gave mean 28.95 (SD = +/- 0.98) mumol/L, (n = 12). Whole blood 5-HT analysis is unreliable in comparison with platelet-poor plasma.

Blood Platelets↗
PubMedDate not supplied

The metabolism and pharmacology of D-penicillamine in man.

D-penicillamine is rapidly absorbed from the intestine and appears in plasma as free penicillamine, cysteine-penicillamine disulfide, and penicillamine disulfide. Penicillamine binds firmly to serum and tissue proteins. The urinary excretion of S-methyl-D-penicillamine, cysteine-penicillamine disulfide, penicillamine disulfide, and a newly identified metabolite, homocysteine-penicillamine disulfide, has been quantitated for patients with rheumatoid arthritis, cystinuria, and Wilson's disease. Fifty percent of an oral dose is excreted in the feces, but the metabolites have not yet been fully characterized. The pharmacologic effects of D-penicillamine are associated with disulfide bond formation or cleavage, thiazolidine formation, and metal chelation.

Absorption↗
PubMedDate not supplied

Rheumatoid synovial cell proliferation, transformation and fibronectin secretion in culture.

OBJECTIVE: There is some experimental evidence that patients with rheumatoid arthritis (RA) have a defect in the control of cellular proliferation. To examine this further, synovial cells from patients with RA and osteoarthritis controls (OA) were studied for phenotypic characteristics of transformation and proliferation. METHODS: Synovial cells grown in vitro were studied to determine the extent of proliferation, anchorage-independent growth, growth under reduced serum conditions, fibronectin secretion, and the presence of cell proliferation antigens. RESULTS: RA synovial cell proliferation was less than that recorded for normal skin fibroblasts and was not increased compared to OA synovial cells. Studies of growth in soft agarose showed no colony formation by RA or OA synovial cells after 28 days, indicating that anchorage-independent growth does not occur. At low serum concentrations RA and OA synovial cells showed similar growth. Fibronectin was constant for each cell line studied, irrespective of the cell number or diagnosis. RA cells did not show an increased rate of fibronectin secretion. RA cells did not show an increased expression of proliferating cell antigens. CONCLUSION: These studies do not support the concept that defective proliferation of synovial cells is a major factor in the pathogenesis of RA.

Animals↗