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Biomedical subjects

H A Lee

Publications and source records attributed to H A Lee.

At least 37 records · Page 2Linked to original sources
PubMed1996

L-carnitine and acetyl-L-carnitine status during hemodialysis with acetate in humans: a kinetic analysis.

The effects of the acetate content of hemodialysis fluids on the relation between L-carnitine (free carnitine, cr FC) and acetyl-L-carnitine (AC) have not previously been examined in detail. The net fluxes of FC, AC, and acetate between intra- and extracellular pools during hemodialysis were calculated using a kinetic model with dialysates containing three concentrations of FC (0, 40, and 80 mumol/L) and either 40 or 3 mmol acetate/L. Radioenzymatic assays of FC and AC were optimized for use with samples taken during hemodialysis. Acetate stimulated a tissue uptake of FC (P < 0.05) that could exceed the rate of FC delivery and was related to the dialysate FC composition (P < 0.02). There were associated changes in tissue AC output. With dialysate containing 40 mmol acetate/L, AC tissue output was directly related to the dialysate FC composition (P < 0.05). The AC tissue output was less with dialysate containing 3 mmol acetate/L (P < 0.05) but the significant increase with the provision of FC in the dialysate was retained (P < 0.05). Hemodialysis may therefore represent an acute period of relative carnitine deficiency when regeneration of free coenzyme A from acetyl coenzyme A consequent to metabolism of acetate is limited.

Acetates↗
PubMed1996

Surface ultrastructures of the third-stage larvae of Gnathostoma hispidum.

A scanning electron microscopic study was performed to observe the surface ultrastructures of the third-stage larvae of Gnathostoma hispidum. The early third-stage larvae (EL3) were collected from the viscera of Chinese loaches by the artificial digestion method. The advanced third-stage larvae (ADL3) were recovered from mice experimentally infected with EL3. Both larval worms were fixed with 2.5% glutaraldehyde, dehydrated in graded alcohol, dryed in critical point dryer, and coated with gold. The specimens were observed with a SEM (DS-130C). On the head bulb of both larval stage, the mouth had a pair of lateral lips of equal size and of half moon shape. Each lip had a couple of labial papillae and a small amphid located between the two papillae. The hooklets on the head bulb had single-pointed tips and curved posteriorly. The cuticular spines of EL3 were larger and more densely distributed in the anterior area (about 1.8 micron in length) and gradually decreased in size and number posteriorly. The cuticular spines in the anterior area of ADL3 were sharp-pointed and about 4.5 micron in length, and those in the middle area were about 1.75 micron. The velvety cuticular folds and dot-like cuticular spines were distributed in the posterior area. A cervical papilla was located between the 7th and 8th transverse striations. A dome-like body papilla was located at the posterior 1/4 of body. An ellipsoidal excretory pore was located between the 17th and 18th striations. From the above results, it is suggested that the characteristic SEM findings obtained from this study may be helpful on the species identification of larval Gnathostoma.

Animals↗
PubMed1996

Comparison of a microtitration plate ELISA with a standard cultural procedure for the detection of Salmonella spp. in chicken.

A rapid antibody-capture enzyme-linked immunosorbent assay (ELISA) detecting a wide range of Salmonella serotypes and employing only one culture stage was used to analyze the giblets and body cavity rinsings from frozen chickens. The results from the ELISA were compared with those obtained using a standard cultural procedure in current use in two laboratories, Norwich (N) and Ipswich (I), of the Public Health Laboratory Service (PHLS) in the UK. ELISAs were carried out on the same samples at each of two PHLS laboratories and at the Institute of Food Research with good agreement (94% and 90%). When compared with the cultural method there was 80% and 70% agreement with the ELISA with the PHLS(N) and PHLS(I) samples. The ELISA appeared to have a false-positive rate of 17% (samples from PHLS(N)) but on reculture of the "negative" samples this rate fell to 7%. The false-negative rate for the ELISA was 26% (samples from PHLS(N)) which appeared to be due to insufficient growth of the Salmonella spp. in the single cultural step employed in the ELISA rather than lack of recognition by the antibodies. The problem of false negatives with the cultural method is also discussed. These results are comparable to previously published studies relating immunoassays and the conventional procedure for Salmonella detection when analyzing similar samples. Suggestions are made as to how further increases in ELISA efficiency might be brought about.

Animals↗
PubMed1995

Plasma non-esterified fatty acid response to dialysate acetate concentration during haemodialysis in humans.

We have inhibited the in vitro generation of non-esterified fatty acids in plasma samples taken during haemodialysis by cooling the samples rapidly, centrifuging and freezing within 5 min of sampling and completing the assay on the same day. The relationship of non-esterified fatty acid concentrations during haemodialysis to the acetate concentration of the dialysate and the profile of circulating lipase activities was studied. With this sample-handling protocol we found lower non-esterified fatty acid concentrations than reported in many other studies and the results suggest that, under normal conditions of haemodialysis, the circulating non-esterified fatty acid concentrations and the associated risk of unwanted side-effects may have been previously over-estimated due to artefactual in vitro sample lipolysis. We also showed that, at the end of dialysis, when circulating lipase activities were least, the non-esterified fatty acid concentrations were lower (P < 0.05) with an acetate dialysate containing 37 mmol/l acetate than with a bicarbonate dialysate containing 3 mmol/l acetate.

Acetates↗
PubMed1993

Combined 17 alpha-hydroxylase/17,20-lyase deficiency caused by heterozygous stop codons in the cytochrome P450 17 alpha-hydroxylase gene.

OBJECTIVE: To determine the genetic defect underlying congenital adrenal hyperplasia due to 17 alpha-hydroxylase deficiency in a genetic female. DESIGN: Blood samples were used as a source of genomic DNA. A library of size selected genomic DNA sequences was prepared. In addition, portions of the 17 alpha-hydroxylase gene were amplified by the polymerase chain reaction and the gene products sequenced. PATIENTS: Samples were obtained from a patient with sexual infantilism, lack of secondary sexual characteristics and hypertension. Streak gonads were found on laparoscopy. RESULTS: Two point mutations were found, one in exon 3 and one in exon 4 which generate premature stop codons at codons 194 and 239 in place of glutamate and arginine respectively. The mutation in exon 3 has not previously been reported in patients with 17 alpha-hydroxylase deficiency. CONCLUSION: The protein product of these defective genes could be expected to be severely truncated with no catalytic activity. This is in keeping with the complete lack of cortisol and sex steroid output in this patient. The polymerase chain reaction provides faster access to gene sequence information than previous procedures based on library screening prior to sequencing.

Adrenal Hyperplasia, Congenital↗
PubMed1993

Further studies on the feasibility of one-day Salmonella detection by enzyme-linked immunosorbent assay.

A model system previously developed for the rapid detection of Salmonella typhimurium in foods was improved and extended to many other Salmonella serotypes. The original protocol, which consisted of an overnight nonselective culture followed by a specific enzyme-linked immunosorbent assay (ELISA), was modified and improved. A sandwich ELISA which used polyclonal antibodies for the capture stage and a cocktail of monoclonal antibodies for the detector stage was developed. The assay recognized a wide range of Salmonella serotypes; S. enteritidis, the most important serotype in the United Kingdom had a detection limit in the ELISA of about 4 x 10(2) cells ml-1. The cultural stage prior to the ELISA was either a single nonselective broth (incubated for 28 h) or a preenrichment broth (incubated for 7 h) plus a selective broth (incubated for 21 h). Antibodies which bind to cells grown in the unfavorable conditions of a selective medium were selected. It was concluded that, in the future, the shortened protocols for the detection of Salmonella spp. in foods described here will be of considerable value.

Animals↗
PubMed1992

Lack of correlation between IgG T-lymphocyte flow cytometric crossmatches with primary renal allograft outcome.

The flow cytometric crossmatch (FCXM) has been reported to be more sensitive and capable of detecting very low levels of antibodies than the normally used complement dependent cytotoxicity test. We studied both the two colour IgG T cell FCXM and CDC-XM in 146 renal allograft recipients, 111 primary and 35 regrafts, of which 26% (29/111) of 1st and 20% (7/35) of regrafts had a positive FCXM. There was no overall correlation between the FCXM results and early graft outcome in primary renal allografts. The FCXM did not appear to have any advantage over the CDC-XM in predicting graft outcome in unsensitized first grafts. In the small number of regrafts studied, a positive FCXM was associated with a higher degree of graft failure. FCXM can exhibit false negative results if sera are used solely neat although these prozone phenomena do not influence subsequent graft outcome.

Adult↗
PubMed1991

Uraemia: is urea more important than we think?

Urea is accumulated as an osmolyte by some groups of animals even though it impairs protein function. These organisms can withstand high internal urea concentrations because they also accumulate other low-molecular-weight osmolytes, the methylamines, which can offset the effects of urea on proteins. Methylamines have also been found in the medulla of the mammalian kidney (where urea concentrations are high) and in the plasma of human subjects with chronic renal failure. These findings suggest that previous investigations of the potential contribution of urea to the syndrome of uraemia may have been confounded because of the presence of variable concentrations of protective substances. That naturally occurring methylamines or related substances may prove to have a useful therapeutic role in uraemia is also possible.

Animals↗
PubMed1991

Nuclear magnetic resonance studies of blood plasma and urine from subjects with chronic renal failure: identification of trimethylamine-N-oxide.

We have used 1H-, 13C- and 14N-NMR spectroscopy to investigate the constituents of plasma and urine in 16 patients with chronic renal failure (CRF). Resonances not previously observed in spectra of plasma from healthy volunteers were seen in CRF plasma, including those for trimethylamine-N-oxide (TMAO) and dimethylamine (DMA). A possible analogy with the plasma of elasmobranch fishes, in which TMAO stabilizes proteins in the presence of very high urea concentrations, is noted. The intensity of the TMAO resonance for CRF subjects was correlated with the plasma concentration of urea (R = 0.55) and creatinine (R = 0.74), suggesting that the presence of TMAO is closely related to the degree of renal failure. When normal subjects ate a meal of TMAO-containing fish, TMAO appeared rapidly in the plasma and in the urine. Thus TMAO is efficiently cleared by the healthy kidney. Differences in the interaction of lactate with plasma proteins were detected by NMR, suggesting that uraemia impairs their transport roles.

Adult↗
PubMed1991

Sub-optimal doses of human recombinant erythropoietin markedly lower serum ferritin.

Human recombinant erythropoietin in full dose substantially raises the haemoglobin in patients with end stage renal disease on dialysis. In lower doses no or little rise in haemoglobin is achieved but the ferritin, often very high before treatment, is disproportionately lowered. The hormone therefore may be useful in reducing iron overload in other situations.

Anemia↗
PubMed1990

The effect of surgery and nutritional regimen on plasma lipoproteins and fat metabolites in man.

Plasma lipoproteins and fat metabolites were measured before and during the first five post-operative days in patients undergoing elective abdominal surgery of moderate severity. They received nutrition as total parenteral nutrition (TPN) or 4% dextrose saline (D S ) or isotonic aminoacids (IAA). Surgery caused an immediate fall in total and very low density lipoprotein triglyceride and total high density lipoprotein cholesterol but a rise in the high density lipoprotein subfraction 2 cholesterol. The increase in total triglyceride after 5 post-operative days was due principally to changes in triglyceride not carried by very low density lipoprotein and was related to the type of nutrition provided. There was no evidence of impaired intra-vascular lipolysis.

Journal Article↗
PubMed1990

Azathioprine and allopurinol: a potentially dangerous combination.

We report the association of leucopenia and anaemia in five patients given a combination of azathioprine and allopurinol. Three subjects were renal transplant recipients with mild to moderate impairment of graft function. The complication appeared between 4 and 6 weeks following initiation of the combination therapy. Discontinuation of one of the two drugs resulted in full recovery within 4-8 weeks.

Adolescent↗