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Biomedical subjects

S Hellerstein

Publications and source records attributed to S Hellerstein.

At least 19 recordsLinked to original sources
PubMed1992

Creatinine for estimation of glomerular filtration rate.

The aim of this study was to evaluate the plasma creatinine concentration (PCr) and creatinine clearance (CCr) for estimation of glomerular filtration rate (GFR). Inulin clearance (Cin) was used as the reference standard for GFR. Thirty-nine concurrent Cin and CCr studies provided data for comparing Cin with the measured CCr and with the calculated CCr (calc-CCr). (Calc-CCr = k.L/PCr, where L = height in centimeters and k is the proportionality constant.) Thirty-one children 5.3-20.8 years of age, with Cin ranging from 2.8 to 138.8 ml/min per 1.73 m2, participated in these studies at The Children's Mercy Hospital. The measured CCr was 16.7 +/- 10.3 ml/min per 1.73 m2 (P < 0.001) greater than the Cin, and the calc-CCr overestimated Cin by a mean of 31.6 +/- 20.8 ml/min per 1.73 m2 (P < 0.001). Although there is good correlation between Cin and CCr (r = 0.96), and Cin and calc-CCr (r = 0.90), the 95% confidence intervals are quite broad. Hence, the CCr and the calc-CCr, derived using Schwartz values for k, consistently overestimate GFR. However, if the k value in the equation GFR = k.L/PCr is derived from k = Cin/L, rather than from k = CCr.PCr/L, a more accurate estimate of GFR may be obtained.

Adolescent↗
PubMed1992

Metabolic and histologic investigation of the nature of nephrocalcinosis in children with hypophosphatemic rickets and in the Hyp mouse.

To investigate the biochemical nature of nephrocalcinosis in children with hypophosphatemic rickets treated with orally administered phosphate and vitamin D, we studied five such patients, aged 3.7 to 12.3 years, during treatment and again 3 days after it had been discontinued. Treatment was associated with significant increases in mean serum phosphate concentration and urine phosphate/creatinine ratio, from 0.71 to 1.03 mmol/L and from 3.61 to 9.42 mmol/mmol, respectively. Significant correlation was found between urine phosphate/creatinine and oxalate/creatinine ratios (r = 0.670; p less than 0.01); however, the mean urine oxalate/creatinine ratio of 65.0 mumol/mmol while patients were taking phosphate orally was not significantly different from the ratio of 59.0 mumol/mmol when treatment was discontinued. Kidney biopsy specimens from three of the patients showed that the renal calcifications were located mainly intratubularly and were composed exclusively of calcium phosphate. In a further investigation of the nature of phosphate-induced nephrocalcinosis, six 6-week-old male Hyp mice, the murine analog of the human disease, received oral phosphate therapy with drinking water for 48 days; six others served as control animals. Mice in the experimental group excreted more phosphate (p less than 0.001) and less calcium (p less than 0.01) than control mice did, and medullary nephrocalcinosis, with a high kidney calcium content, developed (p less than 0.001). Histologic sections showed that the renal calcifications were located intratubularly and were composed of calcium phosphate. We conclude that, both in children with hypophosphatemic rickets and in the Hyp mouse, the development of nephrocalcinosis is associated with high oral phosphate intake and subsequent deposition of calcium phosphate precipitates in the kidney.

Animals↗
PubMed1992

Residential summer camp for children with end-stage renal disease.

Residential summer camps exist for children with all varieties of chronic illness with the goal of improving their quality of life. This paper describes the development and implementation of a summer camp for children 9-18 years old who receive long-term peritoneal dialysis or who have received a kidney transplant. Thirty-five to forty children regularly participate in activities such as water olympics, survival hikes and campouts while continuing to receive their medical needs from trained personnel. A study to evaluate the impact of a summer camp revealed less patient hopelessness and improved self-esteem following the 1-week camping experience. Attendance at camp provided the medical staff with a unique perspective of childhood illness, while the period of respite for the parents was uniformly welcomed and may contribute to the prevention of parent burnout. It is hoped that the success of this camp and others like it will lead to the development of similar experiences for other children with chronic disease.

Adolescent↗
PubMed1991

Recombinant human erythropoietin therapy in pediatric patients receiving long-term peritoneal dialysis.

We evaluated the impact of (s.c.) recombinant human erythropoietin (r-HuEPO) therapy on the hematological status, exercise capacity, and dietary intake of nine pediatric patients (mean age 12.4 +/- 3.2 years) receiving long-term peritoneal dialysis. Five children without medical illness served as controls for the exercise testing portion of the study. Following 7.9 +/- 2.8 weeks of twice weekly r-HuEPO (50 units/kg per dose), the hematocrit increased from 21.9 +/- 3.5% to 31.3 +/- 2.5% (P less than 0.001). A further increase to 33.2 +/- 3.0% occurred after 2 months of once weekly therapy. The blood transfusion requirement decreased from 0.5 transfusions per patient-month to 0.05 transfusions per patient-month (P less than 0.01). Graded exercise testing demonstrated an increase in peak oxygen consumption from 17.8 +/- 5.2 to 24.0 +/- 7.6 ml/kg per min (P less than 0.01). The oxygen consumption at anaerobic threshold increased from 13.1 +/- 3.9 to 17.1 +/- 3.5 ml/kg per min (P less than 0.02). Treadmill time increased from 5.3 +/- 1.2 to 7.5 +/- 1.3 min (P less than 0.001). In each case, the percentage improvement was significantly greater than the improvement seen in the control population. Dietary evaluation revealed no significant change in caloric or protein intake, despite a subjectively improved appetite. r-HuEPO, given by the s.c. route, corrects the anemia and improves the exercise capacity of pediatric patients receiving long-term peritoneal dialysis.

Adolescent↗
PubMed1991

Oral acetazolamide in the assessment of (urine-blood) PCO2.

Urine-blood (U-B)Pco2 difference in children is usually assessed following urine alkalinization with oral sodium bicarbonate (NaHCO3). Since oral NaHCO3 is often poorly tolerated by children, we compared oral acetazolamide with oral NaHCO3 in a study of (U-B)Pco2. In the first phase of the study 14 children and adolescents aged 11.1 +/- 3.7 years (mean +/- SD) were studied. Eight participants had normal kidney function and 6 had disturbed distal acidification capacity. Each child was studied twice, once with oral NaHCO3 (2.5 mEq/kg) and once with acetazolamide (17 +/- 2 mg/kg). All studies were performed according to the standard protocol. Acetazolamide administration resulted in a lower blood pH than NaHCO3 (7.30 +/- 0.03 vs 7.38 +/- 0.06, P less than 0.001) and a lower serum bicarbonate (HCO3-) concentration (25.1 +/- 2.2 mEq/l vs 27.5 +/- 2.1 mEq/l, P less than 0.025). Acetazolamide also resulted in a higher urine Pco2 (81.9 +/- 26.2 mm Hg vs 71.6 +/- 18.2 mm Hg) than NaHCO3 (P less than 0.025). No significant differences between acetazolamide and NaHCO3 were observed with respect to their effects on urinary pH and HCO3- concentration, plasma Pco2 and (U-B)Pco2. Good linear correlations were found between the effects of acetazolamide and NaHCO3 on urine Pco2 (r = 0.878, P less than 0.001), and on (U-B)Pco2 (r = 0.795, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetazolamide↗
PubMed1991

Primary nocturnal enuresis: current concepts about an old problem.

In summary, all children and families who present with nocturnal enuresis should be offered education, reassurance, and ongoing support as a premier component of any treatment regimen. At the same time, the family should be informed about all the treatment options that exist with a goal of tailoring the specific treatment to the individual patient. In most cases, this approach will lead to child, family, and physician satisfaction.

Behavior Therapy↗
PubMed1990

Descriptions of the participating centers and patient population in the Growth Failure in Children with Renal Diseases Study.

The Growth Failure in Children With Renal Diseases Study, a double-blind, multicenter clinical trial with 108 children entered into the control period over 4.3 years of patient enrollment (December 1984 to April 1989), is being extended for 3 years (December 1988 to December 1991) to provide the time needed to accrue additional patients, aged between 1 1/2 and 10 years, with glomerular filtration rates of 20 to 75 ml/min/1.73 m2. The study design of randomization to two treatment arms (1,25-dihydroxyvitamin D vs dihydrotachysterol) requires a total of 108 patients with a minimum of 6 months of treatment to test the long-term effectiveness and safety of 1,25-dihydroxyvitamin D, an essential part of the therapeutic regimen for children with chronic renal insufficiency. The frequent longitudinal assessments of nutrition and growth in children with chronic renal insufficiency can better define the natural history of renal disease and its influence on growth. Similar data in the treatment period will define the impact of treatment with 1,25-dihydroxyvitamin D3 versus dihydrotachysterol on this natural history. Linear growth must be observed long enough (6 to 12 months minimum) to permit valid quantitation and comparison of the two vitamin D treatment arms, the multiple confounding variables that affect growth (e.g., steroid therapy, diabetes mellitus, prior vitamin D treatment) must be rigorously excluded or controlled, and the assignment of patients to the two groups must be random. These controls--sufficient study duration, sufficient patient numbers, and randomization--should eliminate extraneous sources of variation, including seasonal periodicity. This carefully developed, double-blind clinical trial with multiple participating centers and an effective organizational structure is coming close to achieving the goals of the study. An explosion of data regarding the natural history of chronic renal insufficiency and its treatment with vitamin D metabolites will be forthcoming at the conclusion of the study.

Child↗
PubMed1990

Nutritional and behavioural aspects of nasogastric tube feeding in infants receiving chronic peritoneal dialysis.

Eight infants initiated chronic peritoneal dialysis and received nasogastric tube feedings during their first month of life. In each case, the nasogastric tube feedings were initiated because of poor oral intake and the desire to avert the development of an aversive feeding interaction between parent and child. The nutritional regimen was designed to allow normal or catch up weight gain appropriate for height age. The caloric and protein intake of the infants averaged 98.5 +/- 10.2 kcal/kg/day and 2.7 gm/kg/day, respectively, during the first year of life. Between 25% and 100% of the formula intake was provided by the nasogastric route. Group standard deviation score for height was -1.74 +/- 0.7 at one year. Five of the infants received behavioral therapy because of persistent food refusal. Therapy consisted of reinforcing prompted food acceptance and ignoring food refusal. This approach was conducted by a multidisciplinary team and successfully converted the non-oral feeder to a total oral feeding regimen in each case.

Enteral Nutrition↗
PubMed1988

Creatinine excretion rates for evaluation of kidney function in children.

A protein load protocol for evaluation of kidney function was tested in normal children and pediatric renal patients. An overnight, timed urine collection was used for calculation of the baseline creatinine clearance and creatinine excretion rate. One hour following ingestion of a standardized protein meal (baked chicken), a 2-3 h urine collection was begun. The post-protein meal changes in creatinine clearance showed considerable variation in both the normal children and those with renal disorders. In contrast, the rate of excretion of creatinine was consistently increased in the normal children following the protein meal (73.4 +/- 18%; range 48.2%-122.4%). Of 33 renal patients, 14 showed less than a 48% increase in creatinine excretion rate, even though 9 of these children had baseline creatinine clearances within the normal range. These 9 patients have evidence of less than normal quantities of functioning renal tissue. Serial studies over a year on 2 children who presented with acute renal failure showed a progressive increase in creatinine clearance with scant increases in creatinine excretion rate. These studies provide indirect evidence that a less than normal enhancement of the rate of creatinine excretion following a protein load reflects the presence of adaptive glomerular hyperfiltration and hyperperfusion.

Adolescent↗