Non-coding RNA in cystic fibrosis

Non-coding RNAs (ncRNAs) are an abundant class of RNAs that include small ncRNAs, long non-coding RNAs (lncRNA) and pseudogenes. The human ncRNA atlas includes thousands of these specialised RNA molecules that are further subcategorised based on their size or function. Two of the more well-known and widely studied ncRNA species are microRNAs (miRNAs) and lncRNAs. These are regulatory RNAs and their altered expression has been implicated in the pathogenesis of a variety of human diseases. Failure to express a functional cystic fibrosis (CF) transmembrane receptor (CFTR) chloride ion channel in epithelial cells underpins CF. Secondary to the CFTR defect, it is known that other pathways can be altered and these may contribute to the pathophysiology of CF lung disease in particular. For example, quantitative alterations in expression of some ncRNAs are associated with CF. In recent years, there has been a series of published studies exploring ncRNA expression and function in CF. The majority have focussed principally on miRNAs, with just a handful of reports to date on lncRNAs. The present study reviews what is currently known about ncRNA expression and function in CF, and discusses the possibility of applying this knowledge to the clinical management of CF in the near future.

Adolescent diabetes management and mismanagement

OBJECTIVE

To document the existence and prevalence of adolescent-generated diabetes management techniques.

RESEARCH DESIGN AND METHODS

One hundred forty-four adolescents completed the confidential questionnaire developed for this study. Glycohemoglobin was also obtained for each individual.

RESULTS

Within the 10 days before their clinic visit, many adolescents admitted to engaging in various mismanagement behaviors, with 25% admitting to missing shots. Parents tend to underestimate adolescent mismanagement. Missing shots was significantly related to poor control (P < 0.01). Older adolescents engaged in more mismanagement than their younger cohorts (P < 0.001). The questionnaire factored into two subscales: blatant mismanagement and faking.

CONCLUSIONS

This study shows the importance of recognizing the prevalence of mismanagement among adolescents.

MRI, clinical, and biochemical features of partial pyruvate carboxylase deficiency

We report a boy with a partial deficiency of pyruvate carboxylase as documented in enzyme assays of skin fibroblasts, lymphocytes, and hepatic tissue. Magnetic resonance imaging at age 20 months demonstrated a leukodystrophic process involving the brain stem and subcortical white matter, which, except for the brain stem, improved after biotin treatment. The lymphocyte pyruvate carboxylase activity of both heterozygous parents slightly increased after receiving oral biotin for 1 month, but a definitive enzymatic response to biotin was not confirmed in our patient. At age 6 years, he is dysarthric with a spastic quadriparesis despite improvements in development and myelination. This is the first demonstration of magnetic resonance imaging changes in this disease.

Organic acids interfere in the measurement of carbon dioxide concentration by the Kodak Ektachem 700

A significant discrepancy was noted in our laboratory between the total plasma carbon dioxide concentration measured by the Kodak Ektachem 700 and the bicarbonate concentration derived from the Corning 170 pH/Blood Gas analyser in an 8-day-old patient. The concentration of total carbon dioxide was 18 mmol/L while the derived bicarbonate was 13 mmol/L. The patient was eventually diagnosed as maple syrup urine disease. This finding led us to examine the effect of various organic acids on the measurement of carbon dioxide by the Ektachem 700. Several interfered significantly. Clinicians should be aware that when organic acid concentrations are increased, the Ektachem 700 total carbon dioxide result may be falsely raised.

Readmissions of children with diabetes mellitus to a children's hospital

The characteristics of children with diabetes readmitted to Children's Hospital during a 5-year period, 1984 to 1989, were compared with those characteristics of new-onset patients admitted for stabilization and education and to outpatients in the Children's Hospital diabetes program to determine which characteristics were associated with patients who were readmitted. Changes in the frequency of readmissions were examined to determine whether the introduction of a diabetes team and a program that emphasizes the importance of ensuring that patients at risk of readmission consistently received insulin injections resulted in a reduction of readmissions. Readmissions occurred more frequently in patients who were black (71% compared with 38% of new-onset patients and 31% of outpatients) (P less than .001), from one-parent homes (56% compared with 27% of new-onset patients and 24% of outpatients) (P less than .001), and without third-party insurance (45% compared with 18% of new-onset patients and 15% of outpatients) (P less than .001). Readmissions were very common at 14 to 15 years of age (39% of readmissions vs 18% of outpatients) and very uncommon in children younger than age 9 (6% of readmissions vs 27% of outpatients) (P less than .001). Fewer readmissions for ketoacidosis occurred in the summer than in any other season (P less than .05). Readmissions fell by 47% over the 5-year period while new-onset patients increased by 85%. The reduction in frequency of readmissions was due to fewer readmissions for ketoacidosis and fewer readmissions in blacks, in patients from one-parent homes, and in patients without third-party insurance.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol and drug use in teenagers with diabetes mellitus

Alcohol and drug use in adolescents with diabetes mellitus was assessed by an anonymous self-administered questionnaire with verification by urine drug screening. Approximately 50% of these adolescents report having tried alcohol and 25% report ongoing use. Almost 25% have tried drugs of abuse and 5% report ongoing use. One of 97 consecutive urine specimens was positive for marijuana. In general, the frequency of alcohol and drug use was less than expected based on other studies of different clinical groups of patients in the same age range. Patients with diabetes who reported drug use or who reported they live in an environment of substance abuse had poorer diabetes control than patients who did not.

Retinol binding protein and prealbumin in Reye's syndrome

Retinol binding protein (RBP) and prealbumin (PA) were analyzed in 29 serum samples from 8 patients with stages II and III Reye's Syndrome (RS), and from 10 healthy fasting children. All RS patients had at least one abnormally low RBP and PA value. A return toward normal was evident within 2-3 days in serial samples. The nadir RBP and PA values in RS (means of 9 and 107 mg/L) were significantly different (p less than 0.001) from those of the controls (RBP mean of 40 and PA of 157 mg/L). A significant correlation was found between RBP and PA serum values in RS (r = 0.7, p less than 0.001); the high admission NH4+ values tended to associate with low RBP levels; however, the correlation was not very high (r = -0.4, p less than 0.01). The presence of an abnormal vitamin A transport system at an early stage of RS raises the possibility of additional abnormalities in vitamin A metabolism in these patients. The findings of reduced serum levels of complement, clotting factors, fibronectin, and now RBP and PA, suggest a marked short-term impairment of hepatic synthesis of proteins and/or their release in RS.

Hypoglycemia, hepatic dysfunction, muscle weakness, cardiomyopathy, free carnitine deficiency and long-chain acylcarnitine excess responsive to medium chain triglyceride diet

Fraternal twins who had fasting hypoglycemia, hypoketonemia, muscle weakness, and hepatic dysfunction are reported. The hepatic dysfunction occurred only during periods of caloric deprivation. The surviving patient developed a cardiomyopathy. In this sibling, muscle weakness and cardiomyopathy were markedly improved by a diet high in medium chain triglycerides. There was a marked deficiency of muscle total carnitine and a mild deficiency of hepatic total carnitine. Unlike patients with systemic carnitine deficiency, serum and muscle long-chain acylcarnitine were elevated and renal reabsorption of carnitine was normal. It was postulated that the defect in long-chain fatty acid oxidation in this disorder is caused by an abnormality in the mitochondrial acylcarnitine transport. Detailed studies of the cause of the hypoglycemia revealed that insulin, growth hormone, cortisol, and glucagon secretion were appropriate and that it is unlikely that there was a major deficiency of a glycolytic or gluconeogenic enzyme. Glucose production and alanine conversion to glucose were in the low normal range when compared to normal children in the postabsorptive state. The hypoglycemia in our patients was probably due to a modest increase in glucose consumption, secondary to the decreased oxidation of fatty acids and ketones, alternate fuels which spare glucose utilization, plus a modest decrease in hepatic glucose production secondary to decreased available hepatic energy substrates.

Ammonia metabolism in dogs with portacaval shunts

Plasma ammonia, arginine, citrulline and urine ammonia, total nitrogen, and orotic acid were measured in shunted and control dogs. The progressive rise in plasma ammonia in the experimental group could not be explained solely by shunt hemodynamics. Similarity of control and experimental urinary nitrogen does not implicate nitrogen load. Urea synthesis was similar in experimental and control liver slices and was augmented by ornithine only in the experimental slices. Additionally, elevated urine orotic acid suggests urea cycle compromise at the ornithine transcarbamylase step.

A new method for measuring urinary orotic acid

A relatively simple and specific method for measuring urinary orotic acid is reported. With this method, orotic acid is enzymatically converted to uridine 5-phosphate. The difference in absorbance produced by a simple colorimetric procedure in the presence and absence of the enzymatic conversion allows specific measurement of orotic acid. Normal values for urine are less than 4 micrograms/mg creatinine in infants and less than 3 micrograms/mg creatinine in older children and adults.

Primary systemic carnitine deficiency. II. Renal handling of carnitine

Renal tubular reabsorption rates, reabsorptive maxima, and apparent renal plasma excretory thresholds for carnitine were determined in four children with primary systemic carnitine deficiency (SCD), in two of the mothers of these children, in one patient with muscle carnitine deficiency (MCD), and in seven controls. In SCD the observed values were well below those found in six of seven controls, but one control, a healthy 20-year-old woman with normal muscle carnitine level, also exhibited a renal carnitine leak. In the two mothers of patients with SCD and in the case of MCD some of the parameters of the renal handling of carnitine were slightly altered. Tubular secretion of short-chain acylcarnitines was noted in patients and controls at high plasma free carnitine levels. Augmented excretion of short-chain acylcarnitines occurred at lower plasma free carnitine levels in the patients with SCD than in the other subjects. Free and short-chain acyl-carnitines may compete for the same renal reabsorptive site. A renal defect cannot fully account for primary SCD but may contribute to the carnitine depletion in this disorder.

Relationships between control and serum lipids in juvenile-onset diabetes

The relationship between control and serum lipids was examined in 147 children with juvenile-onset diabetes (JOD). Control was assessed by fasting blood glucose, 24-h urine glucose, and fast hemoglobin. There was a significant positive correlation (P less than 0.001) between each of the measures of control. Serum cholesterol (P less than 0.001), triglycerides (P less than 0.001), and low-density lipoprotein plus very low-density lipoprotein cholesterol (P less than 0.001) were strongly positively correlated with control for the whole group of patients. High-density lipoprotein was not significantly correlated with control when the data for the whole group were analyzed but was significantly positively correlated with fasting blood glucose when patients were analyzed individually.

Studies of the cause and treatment of hyperammonemia in females with ornithine transcarbamylase deficiency

Assay of ornithine transcarbamylase (OTC) activity in multiple small bits of liver (approximately 5 mg) that were obtained from a single surgical biopsy in a patient with OTC deficiency revealed a 10- to 40-fold variation in enzyme activity. Similar studies with control autopsy liver specimens varied 2.5-fold at most. The greater variation in the patient with OTC deficiency probably is due to sampling of clusters of normal or abnormal hepatocytes that resulted from inactivation of either the abnormal or normal X chromosone. Enzyme activity assayed on small liver biopsy specimens may not be representative of the entire liver in female patients with OTC deficiency. The hyperammonemia in individuals heterozygous for OTC deficiency may be due in part to shunting of blood through multiple "metabolic portosystemic shunts." Treatment of a girl who has OTC deficiency with a low-protein diet, a low-protein diet supplemented with oral essential amino acids, and a low-protein diet plus oral ketoacids of essential amino acids, on a separate occasion, a low-protein diet was compared to a low-protein diet plus lactulose. The low-protein diet plus oral ketoacid supplementation resulted in the best metabolic control of the patient's disease. On the other hand, paradoxical transient hyperammonemia was observed after the intarvenous administration of ketoacids to two acutely ill female patients with OTC deficiency.

Hyperthyroidism in juvenile diabetes mellitus

Three cases of hyperthyroidism occurring in juvenile patients with diabetes mellitus are presented. The presence of hyperthyroidism should be suspected in patients with diabetes mellitus when goiters develop and when there is unexplained weight loss, tachycardia, tremors, unexplained increases in insulin requirement, or instability of the diabetes with a tendency toward development of ketosis and/or ketoacidosis.

Effect of 4-pentenoate on rat liver ornithine transcarbamylase

The effect of 4-pentenoate on rat liver ornithine transcarbamylase was studied. No effect was found. It is concluded that the effect of 4-pentenoic acid on ornithine transcarbamylase reported by others was probably due to technical errors. Available evidence indicates that 4-pentenoate inhibits ureagenesis by interfering with mitochondrial energy metabolism, which in turn impairs mitochondrial ornithine transport or depletes mitochondrial ATP, impairing carbamyl phosphate synthesis, or both.

Juvenile diabetes mellitus and serum lipids and lipoprotein levels

Cholesterol, triglyceride, and lipoprotein levels were determined in serum from 40 children with diabetes and from controls. Mean cholesterol levels in the children with diabetes (205 +/- 78 mg/dl) were statisically higher than for controls (155 +/- 27 mg/dl), as were mean triglyceride levels (120 +/- 63 vs 85 +/- 23 mg/dl). Eight of the children with diabetes had hypercholesterolemia, five had hypertriglyceridemia, and nine had combined hypercholesterolemia and hypertriglyceridemia. Low-density lipoprotein levels were statistically higher and high-density lipoprotein levels statistically lower for children with diabetes compared with control children. Increased urine glucose spillage was found to correlate with higher serum triglyceride levels, suggesting that the elevated triglyceride levels may have been related to diabetes control. With the known association between hyperlipidemia and coronary heart disease (CHD) and between diabetes and CHD, the results of the present study indicate that all children with juvenile diabetes mellitus should have a serum lipid analysis annually.

Effect of propionic acid on fatty acid oxidation and ureagenesis

Propionic acid significantly inhibited 14CO2 production from [1-14C] palmitate at a concentration of 10 muM in control fibroblasts and 100 muM in methylmalonic fibroblasts. This inhibition was similar to that produced by 4-pentenoic acid. Methylmalonic acid also inhibited 14CO2 production from [1-14C] palmitate, but only at a concentration of 1 mM in control cells and 5 mM in methylmalonic cells. Propionic acid (5 mM) also inhibited ureagenesis in rat liver slices when ammonia was the substrate but not with aspartate and citrulline as substrates. Propionic acid had no direct effect on either carbamyl phosphate synthetase or ornithine transcarbamylase. These findings may explain the fatty degeneration of the liver and the hyperammonemia in propionic and methylmalonic acidemia.

Effect of pent-4-enoic acid, propionic acid and other short-chain fatty acids on citrulline synthesis in rat liver mitochondria

19 The effect of pent-4-enoic acid, propionic acid and several other short-chain fatty acids on citrulline synthesis in rat liver mitochondria was studied. 2.Pent-4-enoate at 1 mM inhibited mitochondrial citulline synthesis by about 80-90%. It is concluded that pent-4-enoate inhibits citrulline synthesis by interfering with some aspect of mitochondrial energy metabolism. This results in impairment of mitochondrial ornithine uptake or depletion of mitochondrial ATP, which, in turn, impairs carbamoyl phosphate synthesis or both. Evidence in support of this conclusion includes: pent-4-enoate has no effect on citrulline synthesis supported by succinate or exogenous ATP; pent-4-enoate lowers the medium plus mitochondrial ATP concentration; finally, when glutamate is the oxidizable substrate, pent-4-enoate decreases the carbamoyl phosphate concentration in mitochondria incubated without ornithine to minimize citrulline synthesis and impairs the mitochondrial uptake of ornithine, but it has neither effect when succinate is the oxidizable substrate. 4. Propionate, butyrate and crotonate also inhibit mitochondrial citrulline synthesis, but much less than pent-4-enoate. 5. Acetate, pentanoate, pent-2-enoate, hexanoate, octanoate, isovalerate, tiglylate and alpha-methylbutyrate have little or no effect on mitochondrial citrulline synthesis.

Production of the features of Reye's syndrome in rats with 4-pentenoic acid

4-Pentenoic acid, an analog of hypoglycin which is believed to cause Jamaican vomiting sickness, was administered intraperitoneally to rats in an attempt to produce the features of Reye's syndrome in rats. Mean ammonia levels in plasma were found to be elevated approximately four-fold after injection of 200 mg/kg pentenoic acid in fed rats. Pentenoic acid caused hypoglycemia in fasted rats and hyperglycemia in fed rats. In chronic experiments rats were injected intraperitoneally every 4 hr with 50 mg/kg body weight of pentenoic acid for 10 doses, followed by a single dose of 200 mg/kg. The livers of the treated group were enlarged and yellow and showed extensive fatty degeneration. The blood-urea-nitrogen (BUN) was significantly higher and the free fatty acids (FFA's) significantly lower in these rats. This study shows that pentenoic acid administered to rats produces findings similar to those of Reye's syndrome and Jamaican vomiting sickness.

Hyperglycemic response to massive doses of commercial insulin

Commercial insulin in massive doses produces an initial hyperglycemic when given to normal rabbits. Large doses, 15 U./kg., of commercial insulin produce a higher plasma glucose than a smaller dose, 2 U./kg., of the same insulin during a period of thirty minutes following the injection. The initial hyperglycemia and the delay of hypoglycemia appear to be due to glucagon in commercial insulin preparations. As little as 0.1 per cent by weight of glucagon will produce this effect. With multiple injections of large doses of insulin every thirty minutes, an evaluation of plasma glucose is seen after each injection and hypoglycemia can be greatly delayed. A qualitatively similar response is also seen in alloxan diabetic rabbits. It is felt that the hyperglycemic effect might be of importance in the treatment of insulin resistance and might explain some cases of acute insulin resistance.