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Biomedical subjects

J C Fenton

Publications and source records attributed to J C Fenton.

17 recordsLinked to original sources
PubMed1980

Plasma ammonia levels in newborn infants admitted to an intensive care baby unit.

A fatal case associated with severe hyperammonaemia is described in which no urea cycle enzyme deficiency could be found. This prompted further investigation of blood ammonia levels in neonates admitted to the premature baby unit at Hammersmith Hospital. 102 specimens were taken from 42 babies within the first 3 weeks of life; the babies had a variety of clinical conditions. The mean ammonia level was 94.5 mumol/l (132.3 micrograms/100 ml) (range 32-255 mumol/l) (44.8-357 micrograms/ml), SD +/- 41.0). These results, although higher than the range for older babies in hospital, were not as high as in the baby with severe hyperammonaemia. Serial levels in 10 babies suggested that the range of blood ammonia levels was greatest in the first 2 weeks of life and narrowed considerably after this period. Great care is needed in collecting blood samples and measuring them if accuate results are to be obtained.

Ammonia↗
PubMed1979

The use of fluorescein conjugated antisera to identify proteins on stained and dried electrophoresis strips.

Paraprotein bands discovered on routine electrophoresis may be identified immunologically without repeating the electrophoretic separation. It is only necessary to heat the stained and dried strip in a hot air oven to reactivate the antigenic sites and insolubilise the protein. The strip may then be stained using specific antisera conjugated with fluorescein. The absence of prozone phenomena greatly helps in typing of free light chains.

Electrophoresis↗
PubMed1975

Letter: SI units.

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International Cooperation↗
PubMed1975

Ammonia and urea transport by the excluded human colon.

1. Ammonia and urea transport across the colonic mucosa was studied by a perfusion technique in four subjects with colonic exclusion for chronic hepatic encephalopathy. 2. Reduction of luminal pH inhibited net and unidirectional transport of ammonia from lumen to plasma, but net absorption from high luminal concentrations persisted at low pH. 3. Neither addition of urea to the perfusate nor intravenous infusion of urea produced a consistent increase in the colonic excretion of ammonia when ammonia-free solutions were perfused. 4. In one subject intravenous infusion of (15N)-ammonium chloride produced rapid labelling of colonic effluent ammonia and within 60 min the specific enrichments of ammonia in effluent and in arterial plasma were approximately equal. 5. During perfusion of nitrogen-free solutions, only small amounts of urea appeared in the effluent, suggesing limited permeability of the colonic mucosa to urea. 6. These results are discussed in relation to the equilibration of ammonia across the colonic mucosa by both ionic and non-ionic diffusion. The lack of evidence of 'juxtamucosal' (as opposed to luminal) ureolysis is in contrast to other observations on the intact colon. The possible reasons for and implications of this discrepancy are discussed.

Ammonia↗
PubMed1968

Improved method for the estimation of plasma ammonia by ion exchange.

Care in the preparation and preservation of reagents, together with certain modifications in apparatus and technique, have eliminated the difficulties from plasma ammonia analysis. Ammonia contamination from the laboratory atmosphere has not proved an especial hazard, and no major setback has been encountered in the analysis of several thousand specimens over the last few years. The method has been found particularly suited to the performance of the occasional estimation, since, once prepared, all reagents are stable for a considerable time.

Ammonia↗
PubMed1968

A stable starch preparation for amylase determinations.

Starch readily dissolves in dimethylsulphoxide (DMSO) to give a clear, colourless solution which is stable and forms a convenient stock starch solution for amylase determinations. Dimethylsulphoxide has no inhibitory effect on serum amylase over a wide range of concentrations.

Amylases↗
PubMed1966

Buzzer ulcers.

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Child, Preschool↗