Steven J. Wassner

A rapid, sensitive method for the determination of 3-methylhistidine levels in urine and plasma using high-pressure liquid chromatography

Abstract A method is presented for the precolumn derivatization and subsequent high-pressure liquid chromatographic separation of 3-methylhistidine from urine and plasma. The solvent system is 10 m m sodium phosphate (pH 7.5) and acetonitrile. The elution can be performed isocratically and requires less than 10 min. Both fluorescent and ultraviolet detection may be utilized. This method is at least 10 3 times more sensitive than conventional ion-exchange chromatography using ninhydrin. 3-Methylhistidine determinations performed on plasma and urine samples from normal volunteers correlated well with published literature values.

Vitamin D Deficiency, hypocalcemia, and increased skeletal muscle degradation in rats.

The myopathy associated with vitamin D deficiency was examined in vitamin D-deficient and vitamin D-supplemented rats. When compared with either vitamin D-supplemented ad lib. or pair-fed rats, weight gain and muscle mass were decreased in vitamin D-deficient hypocalcemic animals. With the exception of a modest decrease in muscle creatine phosphate levels, muscle composition was unchanged by vitamin D deficiency. Muscle protein turnover rates were determined in both in vivo and in vitro studies and demonstrated that myofibrillar protein degradation was increased in vitamin D deficiency. Normal growth rates could be maintained be feeding the rats vitamin D-deficient diets containing 1.6% calcium, which maintained plasma calcium within the normal range. In addition to its role in maintaining plasma calcium, vitamin D-supplemented rats had significantly higher levels of the anabolic hormone insulin. Vitamin D supplementation may affect muscle protein turnover by preventing hypocalcemia, as well as directly stimulating insulin secretion, rather than by a direct effect within skeletal muscle.

Altered Growth and Protein Turnover in Rats Fed Sodium-Deficient Diets

ABSTRACT: The effects of feeding a sodium-deficient (NaD) diet were examined in young, growing rats. All animals were fed the same diet and drank distilled water. In the control group the water contained 37 mM sodium chloride. After 2-3 wk body composition measurements were performed and epitrochlearis muscle protein synthesis and degradation rates determined. The experimental group gained only 45% of the wt and 70% of the length seen in the control group. The difference in wt gain could not be accounted for by differences in extracellular volume which averaged only 4% of body wt. Although total food intake was equivalent in both groups, urinary ammonia plus urea nitrogen excretion was higher in the experimental animals. Protein synthesis, measured as the incorporation of 14C-phenylalanine into muscle protein was significantly lower in NaD rats (56.58 versus 68.79) and (65.26 versus 83.88 nmol phenylalanine/h/g wet wt (both p < 0.01) when incubated with or without the addition of insulin (1 mU/ mL). Net protein degradation rates were unchanged. Gastrocnemius muscle RNA concentrations were also lower in NaD rats (1.09 versus 1.52 mg/g wet wt, p < 0.001). There were no changes noted in the concentration of protein within either gastrocnemius or epitrochlearis muscles. These results suggest that in rats, the growth failure seen in sodium deficiency: 1) affects both length and wt gain; 2) is not associated with decreased nutrient intake; 3) is due to decreased rates of muscle protein synthesis without affecting net protein degradation rates; and 4) is associated with diminished muscle tissue RNA concentrations.

Extracellular fluid restoration in dehydration: a critique of rapid versus slow.

Abstract We compared current recommendations for treatment of severe dehydration by World Health Organization physicians and by the American Academy of Pediatrics Committee on Pediatric Gastroenterology with those in general textbooks of pediatrics, written mostly by pediatric nephrologists. The former recommend rapid (1- to 2-h) and generous intravenous restoration of extracellular fluid (ECF) volume followed by oral rehydration therapy (ORT) to replace potassium, current maintenance, and diarrheal losses – the rapid rehydration regimen. Oral feedings usually are resumed in 8–24 h. General textbooks of pediatrics usually recommend giving 20 ml/kg saline ”to restore circulation,” followed by the deficit therapy regimen to correct serum electrolyte abnormalities and replace remaining deficits of water, sodium, chloride, and potassium over 1–2 days. Mortality for hospitalized patients with dehydration treated with rapid rehydration was <3 per 1,000; no recent results are reported for patients treated by deficit therapy. The rapid rehydration regimen improves patient well being and restores perfusion, so that oral feedings are readily tolerated and renal function corrects serum electrolyte abnormalities in 6 h. Amounts of saline given correspond to amounts given for treating various forms of shock. Deficit therapy regimens provide less ECF restoration and are slower at restoring perfusion; tolerance for oral feedings is delayed. Two hundred pediatric nephrologists were surveyed, asking how they would treat a patient with severe dehydration and a patient with 40% burns. Only 30 of 200 responded; 29 used a deficit therapy regimen, with 20–40 ml/kg ECF replacement, while a majority rapidly and generously restored ECF volume in burn shock. We recommend that fluid therapy chapters should stop teaching deficit therapy for treating severe dehydration and instead teach the rapid rehydration regimen.

The adverse effect of anticonvulsant therapy on renal allograft survival. A preliminary report.

Administration of anticonvulsant medication to recipients of cadaver renal allografts appears to be associated with decreased allograft survival. The one-and two-year actuarial graft survival rates for 20 index grafts was significantly lower than for 92 control grafts. Since phenobarbital and diphenylhydantoin increase the metabolism of corticosteroids, it is proposed that renal allograft recipients receiving these anticonvulsants may have ineffective immunosuppression, leading to a higher incidence of graft failure.

Diminished Linear Growth Associated with Chronic Salt Depletion

*Department of Pediatrics, Penn State University College of Medicine, The Milton S. Hershey Medical Center, Hershey PA 17033 Correspondence to: Steven J. Wassner, MD, Department of Pediatrics, Penn State University College of Medicine, The Milton S. Hershey Medical Center, P.O. Box 850, Hershey, PA 17033 Chronic salt depletion may be found in a variety of conditions associated with failure to thrive. Infants bom

The effect of sodium repletion on growth and protein turnover in sodium-depleted rats

This study examines the consequences of sodium chloride supplementation to young rats previously made salt deficient by feeding them a sodium-deficient, chloride-replete diet. Salt-deficient rats received the test diet and distilled water for 10 days. As in our previous studies, rats cared for in this manner grew more slowly than rats fed the identical diet but allowed to drink 37 mM sodium chloride. On day 11, half of the salt-depleted animals received 37 mM sodium chloride in their drinking water. Sodium-deficient and supplemented rats were studied 1, 2, 5–6 and 11–12 days later. Urinary sodium rapidly rose from undetectable to 46 mEq/l urine within 1 day of supplementation and there was no further increase the next day, suggesting that extracellular fluid volumes were rapidly repleted. Food intake increased in the supplemented rats compared with the deficient animals but the difference in food intake equalled only 2.25 g/day for the first 2 days of supplementation. Over the last 12 days of the first 2 days of supplementation. Over the last 12 days of the study, the slopes of both weight and length gains were equal in both the supplemented and the control group and significantly higher than those in the deficient rats. Over the course of the study, full catchup was not obtained in either length or weight. In addition to total weight and length gains, liver and kidney weights increased proportionately and by 5–6 days of supplementation were equivalent to the weights seen in the control group. After 2 days of supplementation, the incorporation of14C-phenylalanine into epitrochlearis muscle preparations increased 21% (P=0.02) and by 5–12 days after supplementation, muscle protein synthesis rates increased 30%–40% (P=0.01). Net degradation, was not significantly altered by sodium repletion. Whether measured as total gastrocnemius (or liver) RNA or as the ratio of RNA/DNA, RNA levels rapidly increased after sodium chloride supplementation (P<0.01). Thus, sodium supplementation rapidly restores weight gain and linear growth, muscle and liver RNA levels and muscle protein synthesis rates in young, salt-depleted rats. Since salt depletion may exist in a variety of clinical conditions often associated with poor growth, its presence must be considered in attempts to maximize growth in infants and children with chronic illness.

Thyroid Function in Children with Chronic Renal Failure

Thyroid function was evaluated in 24 children (aged 4-18 years) with chronic renal failure either before institution of hemodialysis or after more than 3 months of hemodialysis. 22 patients were clinically euthyroid and 2 were hypothyroid; in one case hypothyroidism was secondary to cystinosis and in the other it followed radiation therapy. The 2 hypothyroid patients had subnormal levels of T4, T3, FTI and FT4 as well as elevated serum TSH levels. Mean values for T4, T3, FTI and FT4 for the remaining 22 patients were within the normal range, but were significantly decreased, (all p values less than 0.01) when compared to controls. TSH and TBG levels were not significantly different from those of the normal population. Eleven of the euthyroid patients (50%) had either T3 or FT4, but not both, below the normal range without elevation of their TSH levels. These findings suggest that in the absence of other causes of hypothyroidism, children with chronic renal failure are able to maintain a clinically euthyroid state with either normal FT4 or T3 serum levels and can respond to primary gland failure with elevated TSH secretion.

The role of nutrition in the care of children with renal insufficiency.

Although appropriate nutrition may not reverse the progression of renal disease or restore growth and body composition to normal, inattention to dietary factors is associated with more severe growth failure, more significant alterations in body composition, and more rapid deterioration in the patient’s sense of well-being. This article identifies the nutritional problems associated with chronic renal insufficiency and suggests tentative approaches to treatment.

Current Thinking in Transplantation in Infants and Children

Renal and liver transplantation are now recognized as therapeutic modalities for children with kidney and liver failure. This article reviews the general indications for transplantation, recipient selection, descriptions of the procedures, and the expected outcome of these two procedures in the pediatric setting.