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Biomedical subjects

R Couper

Publications and source records attributed to R Couper.

29 records · Page 2Linked to original sources
PubMed1993

Immunoreactive calmodulin in cystic fibrosis kidneys.

BACKGROUND: Microscopic nephrocalcinosis has been detected at autopsy in 35 of 38 (92%) cystic fibrosis (CF) patients. A primary defect of calcium metabolism in the kidney has been postulated. Intracellular calcium and calmodulin (a calcium binding protein) have been shown to be increased in CF tissues. AIMS: To determine whether CF kidneys obtained at autopsy contain normal amounts of calmodulin and whether the presence of immunoreactive calmodulin correlates with nephrocalcinosis. METHODS: An immunoperoxidase method was used to stain kidneys obtained from six CF individuals aged three to 27.5 years (mean 15.75 +/- 10.2 years) and five individuals who died of chronic debilitating disease aged eight to 17 years (mean 13.6 +/- 3.9 years). Calcium staining was undertaken using the von Kossa (silver precipitation) and Alizarin red methods. RESULTS: No quantifiable difference in immunoreactive calmodulin staining was demonstrated in autopsy renal specimens between six CF patients and five chronically diseased controls. Three of six CF patients aged 22.8 +/- four years and two of five chronically diseased controls aged eight to 16 years respectively had detectable immunoreactive calmodulin staining. Within the CF group the presence of microscopic nephrocalcinosis did not correlate with immunoreactive calmodulin staining. CONCLUSION: This study does not support the premise that a calmodulin-dependent defect of intracellular calcium handling contributes to the microscopic nephrocalcinosis seen in CF.

Adolescent↗
PubMed1992

Exocrine pancreatic function in children with systemic lupus erythematosus.

We examined the incidence and spectrum of pancreatic disease in pediatric systemic lupus erythematosus (SLE). We measured serum immunoreactive cationic trypsinogen (IRT) in 185 samples obtained from 35 patients with SLE. Fifteen patients (43%) had elevated IRT levels on at least one occasion. Serum samples were obtained in 20 of 35 patients before start of treatment. Seven of these 20 patients (35%) had elevated IRT levels at diagnosis, which slowly returned to normal as their disease was controlled with treatment. A further 3 of these 20 patients in whom we had sera at diagnosis had elevated levels at some course during their illness. Of the remaining 15 patients in whom sera was not available at diagnosis, 5 patients had increased IRT levels on at least one occasion. We show that elevated IRT levels are common in pediatric SLE, but there was no apparent association with drugs such as prednisone and azathioprine. However, high levels of IRT at the time of diagnosis may be related to an underlying disease component such as vasculitis.

Adolescent↗
PubMed1991

Neutrophil dysfunction in glycogen storage disease Ib: association with Crohn's-like colitis.

Two cases of patients with Crohn's-like colitis and glycogen storage disease Ib have been reported previously. In the current report, chronic inflammatory bowel disease that developed in another adolescent with this glycogenosis is described, thereby corroborating the association. The neutrophil dysfunction observed in glycogen storage disease Ib is the most likely predisposing factor. Neutrophil function was investigated in our patient in an attempt to shed light on the pathogenesis of his intestinal inflammation. The patient displayed reduced neutrophil chemotaxis to zymosan-activated serum, N-formyl-methionine-phenylalanine, and Escherichia coli bacteria-derived factor and reduced intracellular killing of Staphylococcus aureus 502A. Others have found this defective bacteriocidal activity to be caused by impaired oxidative metabolism. The recent recognition of chronic inflammatory bowel disease in glycogen storage disease Ib, as well as in chronic granulomatous disease, suggests that further study of respiratory burst activity of neutrophils in Crohn's disease is warranted.

Adolescent↗
PubMed1991

Serum immunoglobulin G directed against porcine trypsin in pancreatic insufficient cystic fibrosis patients receiving pancreatic enzyme supplements.

Cystic fibrosis (CF) patients frequently malabsorb nutrients because of pancreatic failure. Standard therapy entails oral administration of porcine pancreatic enzymes, with meals. Porcine enzymes contain in excess of 25 potentially antigenic proteins. To evaluate antigenicity of one of these (porcine trypsin), we developed ELISA techniques capable of measuring total immunoglobulin G (IgG) and IgG directed against porcine trypsin in patient sera. Cross-sectional evaluation of sera from 12 controls and 41 CF patients showed that IgG directed against porcine trypsin was detectable in 12/17 CF patients receiving porcine enzymes (50.6 +/- 56.0 ng/ml; range 0-154.0 ng/ml), while none was detected in controls or the 26 CF subjects not receiving enzymes. In the 17 CF patients receiving enzymes, porcine trypsin binding IgG contributed 0.85 +/- 0.83% of the total IgG pool. Levels of porcine trypsin binding did not correlate with total IgG. Longitudinal evaluation was then performed in 26 CF patients, before and after commencement of enzyme therapy. Prior to commencing therapy, porcine trypsin binding IgG was undetectable in sera from 24/26 patients. Within 4.2 years of commencing therapy, 25/26 patients (96%) developed porcine trypsin binding IgG. Thus, serum IgG responses to porcine trypsin appear to be common in CF patients receiving porcine enzymes and contribute considerably to total IgG levels. Other individual enzymes in porcine extracts are likely to elicit similar antigenic response.

Administration, Oral↗
PubMed1990

Renal calcium handling in cystic fibrosis: lack of evidence for a primary renal defect.

Because cystic fibrosis (CF) epithelia have ion transport abnormalities that may in part be regulated by intracellular calcium metabolism, and the kidney is actively involved in both ion transport and calcium homeostasis, we have investigated renal calcium handling in CF. Twenty-four-hour urine collections were analyzed in 34 CF patients (age 5 to 35 years) and kidney ultrasound studies were performed in 17 CF patients (age 6 months to 23 years). Renal histologic findings at postmortem examination of 14 CF patients (age 4 months to 23 years) were compared with those of 12 patients (age 11 months to 17 years) with other chronic illnesses (6 congenital heart disease, 6 malignancy). In 30 of the 34 CF patients urinary calcium excretion was normal (less than 4 mg (0.1 mmol)/kg/24 hr). Four CF patients had hypercalciuria (calcium excretion 4.4 to 8.8 mg (0.11 to 0.22 mmol)/kg/24 hr). However, these patients had other possible explanations for hypercalciuria, such as immobilization (n = 2), increased dietary sodium load (n = 1), and glucocorticoid therapy (n = 1). None of the 17 patients examined by renal ultrasonography had nephrocalcinosis. Five CF patients had histologic evidence of sparse nephrocalcinosis at autopsy. However, 6 of 12 autopsy kidney specimens from patients with other chronic illnesses and similar preterminal events also showed nephrocalcinosis. The hypercalciuria and nephrocalcinosis in CF and other chronic debilitating diseases may be explained by factors known to affect calcium handling. Our evidence does not support a primary renal defect as the basis of hypercalciuria and nephrocalcinosis in CF.

Adolescent↗