Responses of body leucine metabolism in children(mean age,15.0 yr) with Crohn's disease and growth failure (x ht and wt, 143.9cm and 37.4kg)were studied before and during dietary supplementation. All children ingested a constant diet (2.35g pro/kg/d and 68Kcal/kg/d), comparable to usual oral intakes, followed by continuous nasogastric feedings of 30% protein and 40% energy increases. At the end of each 7-day period, the children received a primed constant infusion of [1−¹³C]leucine for 4 hrs. Plasma ¹³C-leucine and breath ¹³CO₂ were measured at 15-min intervals during isotopic plateau. Results (μmole/kg/hr,x±SEM) for leucine flux(Q), oxidation(Ox) and incorporation(INC) and endogenous release(REL) were:

Thus there was net leucine conservation with supplementation via increased incorporation, and reduced oxidation and endogenous release. These findings suggest that growth failure in Crohn's is accompanied by abnormalities in leucine metabolism which may be reversed with dietary protein and energy supplementation.

Summary: The diagnosis of transient renal tubular acidosis was made in a 16 months old boy. Bicarbonate titration studies revealed that the acidification defect consisted of an association of proximal and distal tubular acidosis. The effect of experimentally induced potassium depletion revealed that hyperkalemia contributed to the acidification defect. After correction of the acidification disorder a defect in urinary concentration was still present.

Speculation: The different tubular defects of transient renal tubular acidosis are due to reversible (toxic) damage of the tubular membrane. Assessment of distal tubular H⁺ secretion by measurement of (U-B)pCO₂ after oral NAHCO₃ administration is impossible in patients with decreased urinary concentration capacity. The incidence of transient renal tubular acidosis (R.T.A.) reached a peak between 1948 and 1953. This condition was first called idiopathic renal acidosis in infancy and subsequently transient R.T.A. (12). The clinical picture and biochemical disorder as well as longterm prognosis have been studied in great detail (2, 3, 4, 13). However accurate biochemical micro-methods for clinical use allowing a detailed study of the pathophysiologic characteristics of the acidification defect were lacking at that time. In recent years few cases of transient R.T.A. have been published (7, 11, 14, 15). We report a case of transient R.T.A. in which a detailed analysis of the acidification defect was made.

A prospective study was undertaken to determine if urinary LDH isoenzyme assays could differentiate site of infection in patients with urinary tract infection. Thirty children, with a mean age of 6.1 years (23 female and 7 male), were assigned to control, cystitis or pyelonephritis categories based on clinical, laboratory and radiologic criteria. LDH isoenzyme concentrations were measured by a thin film agarose electrophoresis (Pol-E-Stret, Pfizer Co.) and expressed as % of I, II, III, IV and V. Of the 10 controls, one had isoenzyme IV and V in 1.2% and 2.3% concentrations. Of 11 patients with cystitis, one had isoenzyme IV and V in 2.6% and 1.3% concentrations. However, in all 9 patients with pyelonephritis, there was a significant percentage concentration of LDH IV (13.8 ± 8.08) and V (15.1 ± 9.8) activity in the urine. It was concluded that patients with pyelonephritis had significant concentrations of LDH IV and V iso-enzymes in their urine, unlike normal children or those with cystitis. The source of these enzymes is postulated to be the renal parenchyma itself as modified by the disease process. The diagnosis of site of infection could be made by measuring LDH isoenzyme IV and V concentration in all the patients with urinary tract infection.

The effectiveness of two inhibitors of poly-ADP-ribosylation, nicotinamide and 3-aminobenzamide to rescue resting and PHA-stimulated lymphocytes damaged by the combination of deoxycoformycin (dCF) and deoxyadenosine (dAdo), has been evaluated. Incubation with dCF (10⁻⁵M) and dAdo (10⁻⁴M) for 18h inhibited protein and RNA synthesis in unstimulated lymphocytes and impaired the cells to respond to PHA stimulation or to give rise to T-cell colonies in methyl-cellulose. Viability studies showed predominantly dead cells at day 4 in both the unstimulated and PHA-stimulated lymphocytes, whether or not the drugs were removed at 18h. Cell viability at day 4 increased from 13.7% to 41.1% with 3mM nicotinamide and to 28.8% with 5mM 3-aminobenzamide. Although nicotinamide was able to sustain the levels of NAD and reduce the fall in cell ATP concentration, the inhibition by dCF plus dAdo of protein synthesis, RNA synthesis and ability of cells to form colonies in cellulose or to respond to PHA was not reversed. Use of physiological concentrations of dCF (10⁻⁶M) and dAdo (10⁻⁶M), though producing less pronounced effects on cell viability, protein and RNA synthesis still caused toxicity even in the presence of nicotinamide. We conclude that inhibition of ADP-ribosylation with nicotinamide or 3-aminobenzamide does not protect cells in vitro from dAdo toxicity with ADA inhibition and is thus not likely to give significant clinical benefit in ADA deficiency.

Recently three patients with a severely defective T-cell immunity and no measurable activity of purine nucleoside phosphorylase (NP) were described. We had the occasion to observe a 22 months old girl with NP deficiency who was referred to us because of haemolytic anaemia which proved to be due to IgG and IgM incomplete warm autoantibodies against red cells. A CMV infection was diagnosed and a bilateral infiltration on chest roentgenograra was evident 4 weeks after admission. The NP activity of the red cells and granulocytes was absent. The parents are both heterozygous for the NP deficiency as well as both grandmothers, whose mothers are half-sisters. T-cell deficiency was demonstrated by negative skin tests to PHA, Varidase and Candida, by absence of E-rosette forming cells, total impairment of in vitro mitogenic response and mixed-lymphocyte reaction. The percentage of surface Ig-bearing lymphocytes and all serum immunoglobulin levels were normal. The clinical history will be fully discussed.

We studied a family with four neonatal deaths due to X-linked myotubular myopathy. The cardinal features of the two index patients included low Apgar scores, weak respiratory efforts requiring intubation and positive pressure ventilation, flaccidity, lethargy, hypotonia, reduced muscle mass, no spontaneous movements, poor grasp, suck, and Moro reflexes, absent deep tendon reflexes, cephalohematomata, narrow chest with thin ribs, undescended testes, and various minor congenital anomalies.

Light microscopy studies revealed variation in cell size and fiber hypotrophy. Fiber typing showed that the small fibers were both Type I and II cells; 90% of larger fibers were Type II A and B. Muscle nuclei appeared prominent and were located centrally in both large and small muscle cells. Small fibers showed prominent hollow centers with thin marginal rims of myofibrils. Larger fibers also had altered myofibril-free centers.

Electron microscopy examinations also noted fiber size variation and central nuclei. The myofibril-free areas contained glycogen and vacuoles. Complex stacks of cylinders comprised of membranes with granular material resembling junctional complexes abutted the central pale regions. Both rough endoplasmic reticulum and ribosomes aligned along the myofilaments were observed.