Dichloroacetate therapy attenuates the blood lactate response to submaximal exercise in patients with defects in mitochondrial energy metabolism.

We determined acute and chronic effects of dichloroacetate (DCA) on maximal (MAX) and submaximal (SUB) exercise responses in patients with abnormal mitochondrial energetics. Subjects (n = 9) completed a MAX treadmill bout 1 h after ingesting 25 mg/kg DCA or placebo (PL). A 15-min SUB bout was completed the next day while receiving the same treatment. After a 1-d washout, MAX and SUB were repeated while receiving the alternate treatment (acute). Gas exchange and heart rate were measured throughout all tests. Blood lactate (Bla) was measured 0, 3, and 10 min after MAX, and 5, 10, and 15 min during SUB. MAX and SUB were repeated after 3 months of daily DCA or PL. After a 2-wk washout, a final MAX and SUB were completed after 3 months of alternate treatment (chronic). Average Bla during SUB was lower (P < 0.05) during both acute (1.99 +/- 1.10 vs. 2.49 +/- 1.52 mmol/liter) and chronic (1.71 +/- 1.37 vs. 2.39 +/- 1.32 mmol/liter) DCA vs. PL despite similar exercise intensities between conditions ( approximately 75 and 70% maximal exercise capacity during acute and chronic treatment). Thus, although DCA does not alter MAX responses, acute and chronic DCA attenuate the Bla response to moderate exercise in patients with abnormal mitochondrial energetics.

Several homozygous mutations in the gene for 11 beta-hydroxysteroid dehydrogenase type 2 in patients with apparent mineralocorticoid excess.

Four deleterious mutations are described in the gene for HSD11B2, which encodes the type 2 isoenzyme of 11 beta-hydroxysteroid dehydrogenase (11 beta HSD2). In seven families with one or more members affected by apparent mineralocorticoid excess, this disorder is shown to be the result of a deficiency in 11 beta HSD2. Surprisingly, the patients are all homozygous for their mutation. This results from consanguinity in two families and possibly from endogamy or a founder effect in four of the other five families. The absence of compound heterozygotes remains to be investigated.

Examination of genotype and phenotype relationships in 14 patients with apparent mineralocorticoid excess.

Apparent mineralocorticoid excess (AME) is a genetic disorder causing pre- and postnatal growth failure, juvenile hypertension, hypokalemic metabolic alkalosis, and hyporeninemic hypoaldosteronism due to a deficiency of 11 beta-hydroxysteroid dehydrogenase type 2 enzyme activity (11 beta HSD2). The 11 beta HSD2 enzyme is responsible for the conversion of cortisol to the inactive metabolite cortisone and therefore protects the mineralocorticoid receptors from cortisol intoxication. Several homozygous mutations are associated with this potentially fatal disease. We have examined the phenotype, biochemical features, and genotype of 14 patients with AME. All of the patients had characteristic signs of a severe 11 beta HSD2 defect. Birth weights were significantly lower than those of their unaffected sibs. The patients were short, underweight, and hypertensive for age. Variable damage of one or more organs (kidneys, retina, heart, and central nervous system) was found in all of the patients except one. The follow-up studies of end-organ damage after 2-13 yr of treatment in six patients demonstrated significant improvement in all patients. The urinary metabolites of cortisol demonstrated an abnormal ratio with predominance of cortisol metabolites, i.e. tetrahydrocortisol plus 5 alpha-tetrahydrocortisol/tetrahydrocortisone was 6.7-33, whereas the normal ratio is 1.0. Infusion of [11-3H]cortisol resulted in little release of tritiated water, indicating the failure of the conversion of cortisol to cortisone. Thirteen mutations in the HSD11B2 gene have been previously published, and we report three new genetic mutations in two patients, one of whom was previously unreported. All of the patients had homozygous defects except one, who was a compound heterozygote. Our first case had one of the most severe mutations, resulting in the truncation of the enzyme 11 beta HSD2, and died at the age of 16 yr while receiving treatment. Three patients with identical homozygous mutations from different families had varying degrees of severity of clinical and biochemical features. Due to the small number of patients with identical mutations, it is difficult to correlate genotype with phenotype. In some cases, early and vigilant treatment of AME patients may prevent or improve the morbidity and mortality of end-organ damage such as renal or cardiovascular damage and retinopathy. The outcome of treatment in more patients may establish the efficacy of treatment.

Peritoneal membrane failure in children on peritoneal dialysis.

Peritoneal dialysis (PD) success depends on adequate renal function replacement. Reports in adult dialysis populations indicate the risk of ultrafiltration failure (UF) increases with the time on dialysis. Type 1 UF is the most common. For children, dialysis modalities are temporizing measures until renal transplantation, considered optimal therapy for end-stage renal disease in children, can be performed. Children are frequently on dialysis for less than 2 years prior to transplantation. Thus if type 1 UF frequency increases with time on dialysis, it would be expected to occur less frequently in children, because they often are on dialysis for shorter periods. A retrospective chart review was performed to determine the cause of ultrafiltration failure in children; 172 children, mean age 8.0 +/- 5.5 (SD) years received a mean of 15 +/- 11.9 (SD) months of chronic PD; 39 patients received only continuous ambulatory peritoneal dialysis, 18 received only continuous cycling peritoneal dialysis, 22 received only tidal PD, and 94 received more than one type of PD. Ten patients (5.8%) developed type 2 UF failure as sequellae of atypical peritonitis, Candida albicans (6 patients), Mycobacterium foruitum (2), Achromatium spp. (1), and Pseudomonas aeruginosa (1). There was no significant difference in time on dialysis for children who developed membrane failure. No patients with type 1 or type 3 UF could be identified. It appears that the causes of peritoneal membrane failure in children are different from those in adults.

The ABC's of evaluating children with hematuria.

Hematuria is a common problem in children. Microscopic hematuria is more frequent than gross hematuria. Hematuria is often the initial finding in patients with urinary tract disease, and it is important to differentiate treatable renal involvement from untreatable, or benign, hematuria. The ABC's of hematuria in children were developed to teach the evaluation of children with hematuria to medical students and house staff. The ABC mnemonic helps physicians remember the differential diagnosis: Anatomy, Boulders, Cancer, Drug-related, Exercise, Foreign body, Glomerulonephritis, Hematology and Infection. A clinical algorithm is provided to guide the evaluation of children with hematuria.

Pediatric tissue and organ transplantation in Florida.

Fifty to 100 children receive transplanted kidneys, hearts, livers, or bone marrow in Florida each year and many more bone allografts or other tissues (skin, cornea). Children are in the minority of the total solid organ transplantation but those with successful transplants are strong proponents of the procedure. Many (liver or heart failure) would have died without transplantation; others (kidney failure) would have lived but been tied to dialysis for life. The success rate varies with the organ or tissue transplanted. Some children return to a completely normal life without the need for immunosuppressive medications. Others require them continually. Cyclosporine, azathioprine and prednisone are the most frequently used. Rejection continues to be the leading cause of graft loss. Major impediments to solid organ transplantation are the paucity of acceptable organs and the high cost associated with maintenance of transplant patients.

Barriers to health care for children. How's Florida doing?

Three primary barriers, financial, system, and knowledge, must be overcome to ensure quality health care for all children. Attempts to identify strengths and weaknesses in Florida's child health care system are directed at removing these barriers. Strengths include: an Institute of Child Health Planning, a legislative proposal to link child health insurance to school enrollment, several populous cities supporting good medical facilities and the availability of health care for all children. Areas of weakness include: lack of medical resources in underserved areas, disproportionate spending on health care for elderly versus young, and lack of identified financial resources to pay for school-linked health insurance.

Developmental changes in the renal capacity for sulfate reabsorption in the guinea pig.

During growth, immature guinea pigs maintain a positive inorganic sulfate balance. In the present study, renal clearance techniques were used to determine the maximum renal capacity for sulfate reabsorption [TmRsi/glomerular filtration rate (GFR)] in three groups of guinea pigs at different stages of development (10-34 days, 35-80 days and greater than 120 days of age). These ages are comparable to infant, adolescent, and adult guinea pigs. The guinea pigs were weaned at 10 days and then maintained on normal guinea pig chow (0.13% sulfate). The TmRsi/GFR was determined by infusions of increasing concentrations of sulfate (0-16.8 mumol/min). TmRsi/GFR was significantly greater in young (infant and adolescent) than in older (adult) guinea pigs (2.20 +/- 0.26 mumol/ml and 1.80 +/- 0.27 mumol/ml vs 0.942 +/- 0.08 mumol/ml, P less than 0.05). These results demonstrate that the tubular capacity for inorganic sulfate reabsorption per milliliter of glomerular filtrate is enhanced in immature guinea pigs and decreases with age.

Calcitriol: a hematolymphopoietrope?

A MEDLINE search of the English-language literature was conducted using the indexing terms 'immunology, calcitriol and vitamin D' to identify studies indicating a role for calcitriol as a primary immunomodulator. Sixty-six papers published between January 1956 and June 1991 were identified. Forty-five of these reports are cited in this review. The data strongly suggest an endocrine, autocrine and/or paracrine role for calcitriol in immune regulation. No unifying hypothesis has yet emerged explaining this collection of data. This paper provides a brief review of immune properties currently attributed to calcitriol.

Adaptation of renal sulfate transport in response to dietary sulfate intake in guinea pigs.

Inorganic sulfate reabsorption was studied during sulfate infusion in guinea pigs stabilized on high-sulfate, normal-sulfate or low-sulfate diets. Guinea pigs stabilized on a low-sulfate diet exhibited 86-91% fractional sulfate reabsorption at normal plasma sulfate concentrations. Fractional renal sulfate reabsorption in animals stabilized on a high-sulfate diet was 55-70%. Clearance techniques were used to determine the glomerular filtration rate and the fractional reabsorption of sulfate during sulfate infusion. Animals fed a high-sulfate diet manifested marked sulfaturia in response to sulfate infusion. The increase in fractional reabsorption associated with decreases in dietary sulfate intake suggests a tubular adaptive mechanism, similar to that demonstrated for phosphate, to increase sulfate reabsorption and maintain constant plasma sulfate concentration. Dietary sulfate-dependent alterations in renal sulfate reabsorption may play a significant role in establishing the rate of sulfate excretion and thus regulating sulfate balance.

Developmental differences in renal sulfate reabsorption: transport kinetics in brush border membrane vesicles.

Renal tubular reabsorption of inorganic sulfate is greater in younger than older guinea pigs. To determine the mechanism of this difference, we studied the transport of inorganic sulfate in renal brush border membrane vesicles (BBMV) obtained from young (< 25 days) and adult guinea pigs (> 60 days). BBMV were obtained by mechanical and osmotic disruption of dissected renal cortices followed by magnesium precipitation and differential centrifugation. After the membranes were incubated for 10 s in solutions containing inorganic sulfate at several concentrations (0.1-10 mM) and trace amounts of 35sulfate, intravesicular uptake was measured. Based on 35sulfur uptake, reabsorption transport kinetics (Vmax and Km) were estimated. BBMV obtained from young guinea pigs demonstrated higher sodium-sulfate cotransport, Vmax (51.79 +/- 4.34 pmol/mg protein per s) than those obtained from adult animals (Vmax = 34.28 +/- 9.17 pmol/mg per s), P < 0.05. Vmax values are represented as means plus or minus standard deviation. No differences in Km were observed. Our results indicate that age-related differences in renal inorganic sulfate reabsorption are due to a higher Vmax for sodium-sulfate cotransport in the younger animals, suggesting a higher density of sodium-sulfate cotransporters or an increased cotransport turnover rate in this age group.

Intrarenal blood flow distribution during endotoxemia in dogs.

Intrarenal blood flow distribution during the stages of endotoxemia in the dog was studied using radioactive inert gas washout. Intrarenal blood flow distribution was determined: a) at control, b) 0.5 hours following injection of a lethal dose (3 mg/kg) of E coli endotoxin, and c) 2.5 hours following endotoxin injection in control dogs and dogs pretreated with 4 mg/kg of phenoxybenzamine. One-half hour following endotoxin injection, components I and II of the inert gas washout curve fused. Presumably this fusion occurred because component I flow decreased to a level indistinguishable from that of component II. Following 2.5 hours of endotoxemia, components I and II were both present. Pretreatment with phenoxybenzamine completely prevented the fusion of components I and II, although the mean arterial blood pressure was substantially lower than in dogs not pretreated with phenoxybenzamine. After 2.5 hours of endotoxemia, four of the five phenoxybenzamine pretreated dogs still had two clearly defined washout components. It is concluded that the renal cortical vascular response in endotoxemia is similar to that reported following hemorrhage and that the alpha-adrenergic nervous system plays a major role in decreasing renal cortical blood flow.

Effects of dopamine on canine intrarenal blood flow distribution during hemorrhage.

Renal blood flow distribution was measured in control dogs, dogs given dopamine, hemorrhaged dogs, and dogs hemorrhaged plus infused with dopamine with a modification of 85Kr washout. Kidneys injected with 85Kr through a renal arterial cannula were removed at several specific intervals after injection, rapidly frozen, and sectioned transversely so that pieces of tissue could be isolated and counted for radioactivity. In the normotensive animals, dopamine appeared to produce a mild vasodilatory effect in the subcortical outer medulla (flow increased 50%). Hemorrhage reduced renal regional flow throughout the kidneys. Subcortical outer medullary flow, however, appeared to be proportionately better maintained than were the more peripheral renal regions, so that all regions had similar flows. Hemorrhaged animals receiving dopamine infusion had statistically significantly higher cortical blood flows than did the animals simply hemorrhaged. From this study, it is impossible to determine if the cortical vasodilation during hemorrhage was a direct or indirect effect on the renal vasculature; however, improved perfusion of the renal cortex during hypotension may partially explain the improved renal function reportedly produced by dopamine infusion in patients in shock.

Renal brush border sodium-sulfate cotransport in guinea pig: effect of age and diet.

Renal adaptation to changes in inorganic sulfate intake and age was studied by comparing sulfate uptake by proximal tubule brush border membrane vesicles (BBMV) from guinea pigs of different ages on relatively high- or low-sulfate diets. Adult (> 60 days) or young guinea pigs (< 25 days) were fed either a control diet (0.28% sulfur content), a sulfur-free diet, or a high-sulfate diet. After 5 days on the diet, BBMV were obtained and kinetic analysis of 35sulfate uptake was determined. In adult guinea pigs, the low-sulfate diet produced a significant increase in apparent maximal velocity (Vmax). In young guinea pigs, a lower sulfate intake did not appreciably increase Vmax, but a high-sulfate intake produced a reduction in Vmax. The affinity for sulfate (Km) was not changed in either age group. The dietary sulfate intake did not alter sodium gradient dependent-D-glucose or 32phosphate Vmax. In conclusion, our data indicate that renal inorganic sulfate BBMV uptake is regulated and responds to conditions of increased need (i.e., during the growth phase in young animals and during periods of decreased sulfate availability in adult animals) by increasing BBMV Vmax.

Severe hemolytic uremic syndrome associated with rhabdomyolysis and insulin-dependent diabetes mellitus.

Hemolytic uremic syndrome has been associated with insulin-dependent diabetes mellitus eight times in the past, while the hemolytic uremic syndrome and rhabdomyolysis association has been described once. The occurrence of both conditions in a patient with the hemolytic uremic syndrome has not been reported. In this report, we described a 28-month-old girl who presented with severe hemolytic uremic syndrome muscle weakness and elevated muscle enzymes. Later, she developed hyperglycemia and ketosis requiring initiation of insulin therapy. The current literature was reviewed, and a hypothesis for the mechanism of injury and the multisystemic nature of this syndrome is presented. In patients with the hemolytic uremic syndrome, identification of potential extrarenal involvement is important as it may determine the final outcome of this disease.

Oral hydration therapy for children in Florida.

Eighty-six children in Florida died of complications associated with diarrhea between 1985 and 1990, deaths which constituted an important preventable fraction of infant mortality. The state will support health professionals in reducing the number of hospitalizations and deaths due to diarrheal complications, Governor Lawton Chiles announced in September 1991, and the Florida Department of Health and Rehabilitative Services is being awarded a $100,000 grant from the Centers for Disease Control for a three-year study on the effectiveness and utilization of oral rehydration therapy. During the last 20 years, a worldwide experience has developed indicating that sodium-glucose cotransport is preserved in both secretory diarrhea (cholera) and diarrhea produced by loss of surface area. This experience indicates that almost no one would die (adult or infant) if oral rehydration solutions and someone with knowledge in their use were readily available. This presentation has three objectives: (1) increase physicians' awareness regarding the state's oral rehydration therapy project; (2) provide a ready practical guide for those using oral rehydration therapy; and (3) promote use of the therapy as treatment for infantile dehydration rather than the more expensive intravenous therapy.

Clinical versus laboratory tumor lysis syndrome in children with acute leukemia.

Renal and metabolic complications of tumor lysis syndrome (TLS) were recognized frequently in the 1960s and 1970s. Strategies were designed to prevent TLS. We conducted a retrospective chart review study to identify the current TLS risk in children with acute leukemia. Children were considered to have "laboratory tumor lysis syndrome" (LTLS) if two of the following metabolic changes occurred within 4 days of the start of chemotherapy: a 25% increase in serum phosphate, potassium, uric acid, or blood urea nitrogen levels, or a 25% decline in serum calcium concentration. Clinical TLS (CTLS) was defined as LTLS plus a serum potassium level higher than 6.0 mmol/L or acute renal failure. Twenty-one of 30 children developed LTLS; one developed CTLS. Absolute blast count, pretreatment white blood cell count, pretreatment lactic dehydrogenase, and sex or tumor DNA index did not correlate with the development of LTLS. LTLS is still frequent in children undergoing chemotherapy for acute leukemia; CTLS, however, is much less common.

Renal reabsorption of phosphate during development: transport kinetics in BBMV.

The mechanism responsible for enhanced reabsorption of phosphate (Pi) in growing animals was assessed in renal brush-border membrane vesicles (BBMV) prepared from 3- to 14-day-old and greater than 57-day-old guinea pigs. On standard diet, Vmax (pmol.mg-1.s-1) of Na+-Pi cotransport was higher (P less than 0.001) in newborn (650 +/- 77) than in adult (144 +/- 17) but Vmax of Na+-glucose cotransport did not differ with age. Low dietary Pi did not affect significantly Vmax of Na+-Pi cotransport in the newborn (P greater than 0.8) but increased it in the adult (to 318 +/- 32, P less than 0.05). A high Pi intake resulted in a smaller relative decrease in Vmax in the newborn than in the adult (27 vs. 44%, P less than 0.05). In the newborn, the serum Pi (mM) decreased on a low-Pi diet (from 1.8 +/- 0.1 to 0.8 +/- 0.1, P less than 0.001) and rose by twofold on the high-Pi diet (to 3.5 +/- 0.2, P less than 0.001). In the adult, there were no significant changes in serum Pi with changes in Pi intake (P greater than 0.5). Thus in the newborn the Na+-Pi cotransport system is characterized by high transport capacity but low adaptability to changes in dietary Pi.