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Biomedical subjects

J F Knight

Publications and source records attributed to J F Knight.

At least 55 records · Page 3Linked to original sources
PubMed1994

Continuous venovenous haemofiltration in the acute treatment of inborn errors of metabolism.

The accumulation of toxic metabolites in children with inborn errors of metabolism may cause acute metabolic crises and result in long-term neurological dysfunction or death. Peritoneal dialysis often provides insufficient clearance to protect against these complications, while intermittent haemodialysis cannot prevent reaccumulation of metabolites between dialysis sessions. We describe the use of continuous venovenous haemofiltration (CVVH) or haemodiafiltration (CVVHD) in three infants with maple syrup urine disease (MSUD) and one child with carbamyl phosphate synthetase (CPS) deficiency. All children with MSUD had a satisfactory reduction in branched-chain amino acids within 24 h of onset of haemofiltration, and are now neurologically normal. The child with CPS deficiency had an ammonia level of < 100 mumol/l within 24 h of onset of therapy, but died 3 days later from unrelated cardiovascular complications. Complications of the therapy included the clotting of one haemofilter and the replacement of two vascular access catheters per patient on average per therapy. Two patients required blood transfusion. We report the successful use of CVVH and CVVHD in the acute management of metabolic crises associated with inborn errors of metabolism, and believe that these may be the optimal techniques for the acute clearance of toxic metabolites.

Acute Disease↗
PubMed1994

Acute obstructive uropathy--a rare complication of circumcision.

We report a rare complication of ritual circumcision in an 8-week-old boy. He presented 1 week after the procedure with reduced urine output, a grossly distended bladder and marked bilateral hydroureteronephrosis on ultrasonography. The acute partial urinary obstruction was due to the dressing which was applied after surgical removal of the foreskin and to oedema of the glans. He had abnormal renal function (creatinine 85 mumol/l, urea 8.5 mmol/l) and a hyperkalaemic metabolic acidosis with hyponatraemia (Na 127 mmol/l, K 6.9 mmol/l, HCO3 16 mmol/l), which were attributed to obstructive uropathy. Because of prolonged secondary bladder dysfunction he required urinary catheterisation for 1 week. There was significant post obstructive diuresis and parenteral fluid therapy was given for 7 days. Whilst urinary retention is a well recognized complication of circumcision, this is the first report of significant obstructive uropathy and renal impairment due to surgical excision of the foreskin.

Acute Kidney Injury↗
PubMed1994

Predominance of T cell receptor V delta 3 in small bowel biopsies from coeliac disease patients.

Increased numbers of T cells bearing the gamma delta antigen receptor (gamma delta T cells) have been reported in small bowel biopsies of patients with latent, active or treated coeliac disease. We have studied jejunal biopsies from seven children with coeliac disease and 10 children with normal gut histology to characterize gamma delta T cell receptor (TCR) variable region gene subfamily expression in resident gamma delta T cells and compared the results with the findings in peripheral blood mononuclear cells (PBMC) obtained on the same day as the gut biopsy. Molecular analysis of RNA extracted from PBMC and biopsies was performed by reverse transcription and amplification with the polymerase chain reaction using primers specific for six TCR V delta families and four TCR V gamma families. We report, first, that a significantly increased number of gamma delta T cells expressing the TCR V delta 3 subfamily (P = 0.008) was observed in jejunal biopsies from children with coeliac disease, and second, that gamma delta T cell V region subfamily populations in gut differed from those seen in PBMC for both control and coeliac patients. Significantly reduced numbers of TCR V delta 2, V delta 3, V delta 5 (P < 0.01) and V gamma 2, V gamma 4 (P < 0.01) T cells were found in gut compared with PBMC. The difference in gamma delta T cell repertoire observed between gut and blood may reflect differences in the nature of the antigens usually encountered in these two compartments. The over-representation of TCR V delta 3 in patients with coeliac disease suggests a specific role for these cells in the induction or maintenance of the jejunal abnormality associated with this disease.

Base Sequence↗
PubMed1994

Total body nitrogen in children with chronic renal failure and short stature.

OBJECTIVE: To directly assess the body protein content of children with chronic renal failure (CRF) and short stature. SETTING: A tertiary referral paediatric hospital. SUBJECTS: There were: (i) 17 patients (10 male, nine pre-pubertal; mean age 12.90 +/- 3.20 years) with CRF and height standard deviation (SD) score < -2.00, and (ii) 43 normal children (18 male, 27 pre-pubertal; mean age 10.34 +/- 3.34 years). INTERVENTIONS: CRF patients had the following measurements: anthropometry, total body nitrogen (TBN) by neutron capture analysis, 4 day weighed food record and serum albumin levels. Control subjects had TBN and anthropometric measurements only. RESULTS: Although older than the controls, the CRF patients had significantly lower TBN values (645 +/- 265 vs 930 +/- 365 g, P < 0.01). Mean values for TBN and TBN/height (percentages of expected) in the CRF patients were significantly reduced to 54% and 63% respectively, when predicted from age. However, their TBN predicted from height was 100% of expected. %TBN (predicted from age) correlated significantly with height SD score (r = 0.79), weight SD score (r = 0.87), upper arm muscle area percentile (r = 0.62) and serum albumin (r = 0.62). Mean oral energy and protein intakes were 65% and 172% of recommended dietary intake respectively. CONCLUSIONS: Children with CRF and short stature are significantly protein-depleted for age although not for height. Chronic energy deficiency may contribute to impaired protein deposition which, in turn, may be important in the pathogenesis of growth failure in CRF.

Adolescent↗
PubMed1990

End-stage renal failure in children: 16 years' experience at one Australian centre.

Sixty-five children over one year and under 15 years of age began treatment for end-stage renal failure between 1973 and 1988. Sixty-one renal transplants were performed in 53 children, 39 of these were from living donors (38 were first-degree relatives and one was an emotionally related volunteer). Thirteen children, of whom seven had received transplants and six had not, died, including three children with functioning transplants; nine deaths occurred in the first eight years of the programme. Cumulative five-year and 10-year patient survival rates were 78% and 75%, respectively. Eighteen transplants failed, 12 as a result of rejection, five as a result of disease recurrence and one due to primary non-function. Cumulative five-year and 10-year transplant survival rates for first grafts were 66% and 53%, respectively. For living donor transplants these rates were 85% and 68%, respectively. Growth rates fell by 0.4 +/- 0.05 standard deviation score (SDS) per year in children undergoing dialysis, were normal in children with renal transplants receiving prednisone (change in SDS per year, -0.02 +/- 0.08) and increased by 0.36 +/- 0.07 SDS per year in children with transplants receiving cyclosporin A alone. Currently, 32 (82%) of 39 transplant recipients and 7 (58%) of 12 patients undergoing dialysis attend school or work full time. Although both dialysis and transplantation are acceptable therapies for children with end-stage renal failure, successful transplantation provides the best opportunity for satisfactory growth and development.

Actuarial Analysis↗
PubMed1990

The rheumatic poison: a survey of some published investigations of the immunopathogenesis of Henoch-Schönlein purpura.

Laboratory studies of the pathophysiology of Henoch-Schönlein purpura (HSP) have become more numerous in recent years with the recognition of the disease's links with the mucosal immune system in general and IgA nephropathy in particular. There are weak genetic associations with C4 null phenotypes and with HLA B35 and DR4. Studies of plasma proteins in HSP patients show an increased IgA concentration, activation of the alternative pathway of complement and consumption of factor XIII. High molecular weight (polymeric) IgA has been detected in affected individuals, which some investigators have called "immune complexes". Many patients synthesise an IgA rheumatoid factor in the acute phase, but other autoantibodies are largely absent. In vitro studies of lymphocytes from HSP patients have demonstrated an increased number of IgA-bearing and secreting B-cells, with altered T-cell regulation of antibody synthesis. While these observations point to immune dysregulation--primarily of IgA production--as a consistent feature of acute HSP, there is as yet insufficient information available to allow a consistent theory of pathogenesis to be formulated.

Blood Proteins↗
PubMed1990

Hyperglycaemia complicating haemolytic uraemic syndrome.

The occurrence of hyperglycaemia and insulin deficiency in a young child receiving peritoneal dialysis during the course of haemolytic uraemic syndrome (HUS) is described. This unusual complication may have been due to microvascular disease involving the pancreas. Plasma glucose should be monitored during HUS, particularly if dialysis with fluids containing high dextrose concentrations is required.

Blood Glucose↗
PubMed1989

Charge distribution of plasma IgA in IgA nephropathy.

The spectrotype of plasma IgA in patients with IgA nephropathy was studied by isoelectric focussing. Densitometry of the gels showed a significant increase in the anionic region at isoelectric points (pI) 4.7-5.1 (P = 0.02) and a reduction in the cationic region pI 5.8-6.0 (P = 0.03) in patients (n = 15) compared with controls (n = 8). Measurement of the IgA concentration in eluates of sequential slices of the gels showed that the ratio of anionic-to-cationic IgA, using pI 5.6 as the dividing point, was significantly greater in patients (n = 10) than in controls (n = 10) (P = 0.03). Two different methods of analysis have therefore demonstrated an increased proportion of anionic and decreased proportion of cationic IgA in the plasma of patients with IgA nephropathy.

Adolescent↗
PubMed1988

Relation of mesangial IgA glomerulonephritis to polymorphism of immunoglobulin heavy chain switch region.

We have investigated the switch regions of Ig heavy chain genes of patients with IgA glomerulonephritis (IgA-GN) using restriction fragment length polymorphism (RFLP) analysis. Genomic DNA from patients and controls was digested with the restriction endonuclease Sst I and transferred to nylon membranes using the Southern blot procedure and hybridized with a probe homologous to the switch region of the Ig C mu gene (S mu) which detects RFLPs in both S mu and the switch region of the Ig C alpha 1 gene (S alpha 1). A significant decrease in the frequency of the 2.6;2.1 kb heterozygous S mu phenotype was found in patients with IgA-GN (P = 0.003). With respect to the S alpha 1 region, there was a significant increase in the frequency of the 7.4 kb S alpha 1 phenotype (P = 0.002). In addition, a significant increase in the frequency of the 7.4 kb S alpha 1 allele was found (P = 0.0002). These results suggest that gene(s) within the Ig heavy chain loci may be important in the pathogenesis of IgA-GN.

Genes, Regulator↗
PubMed1982

Miracle cures.

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Arthritis↗
PubMed1982

Chronic exposure of rats to enflurane 200 p.p.m.: no evidence of toxicity or teratogenicity.

Adult male or female rats were exposed either to enflurane 200 p.p.m. or to air for up to 63 days before mating and subsequently throughout the pregnancy of the females. The treated animals were exposed for 8 h per day, 5 days per week for a maximum total of 100 days. The parents and progeny-were studied. Additional positive controls with vitamin A palmitate demonstrated that the strain of animals was susceptible to a known teratogen. No abortifacient effect was observed with these conditions of exposure to enflurane. Skeletal examination of the fetuses failed to reveal any major teratogenic effect. The parents remained healthy clinically, whilst autopsy and histopathological examination failed to reveal any consistent organ injuries which could be blamed on exposure to enflurane. In rats at least, environmental pollution with enflurane appears not to be associated with significant toxicity or teratogenicity.

Abnormalities, Drug-Induced↗