Familial cerebellar ataxia with muscle coenzyme Q10 deficiency.

OBJECTIVE: To describe a clinical syndrome of cerebellar ataxia associated with muscle coenzyme Q10 (CoQ10) deficiency. BACKGROUND: Muscle CoQ10 deficiency has been reported only in a few patients with a mitochondrial encephalomyopathy characterized by 1) recurrent myoglobinuria; 2) brain involvement (seizures, ataxia, mental retardation), and 3) ragged-red fibers and lipid storage in the muscle biopsy. METHODS: Having found decreased CoQ10 levels in muscle from a patient with unclassified familial cerebellar ataxia, the authors measured CoQ10 in muscle biopsies from other patients in whom cerebellar ataxia could not be attributed to known genetic causes. RESULTS: The authors found muscle CoQ10 deficiency (26 to 35% of normal) in six patients with cerebellar ataxia, pyramidal signs, and seizures. All six patients responded to CoQ10 supplementation; strength increased, ataxia improved, and seizures became less frequent. CONCLUSIONS: Primary CoQ10 deficiency is a potentially important cause of familial ataxia and should be considered in the differential diagnosis of this condition because CoQ10 administration seems to improve the clinical picture.

Correction of glycogen storage disease type II by enzyme replacement with a recombinant human acid maltase produced by over-expression in a CHO-DHFR(neg) cell line.

Inherited genetic deficiency of lysosomal acid alpha glucosidase or acid maltase (GAA) results in the autosomal recessive glycogen storage disease type II (GSD II). To investigate whether we could generate a functional recombinant human GAA (rhGAA) for enzyme replacement therapy, we subcloned the cDNAs for human GAA and mouse dihydrofolate reductase (DHFR) into DHFR(neg) Chinese hamster ovary cells and established a stable cotransformant that expressed rhGAA. We cultured the recombinant cells in media with progressively increasing concentrations of methotrexate and found that human GAA enzyme activity increased to over 2,000 IU per gram protein. Importantly, the human GAA enzyme activity correlated to equivalent amounts of human GAA protein by rocketimmunoelectrophoresis. We confirmed that the human GAA enzyme activity corresponded to an amplification in human GAA mRNA by Northern analysis and human GAA cDNA copy number by Southern analysis. Exposing the rhGAA to human GSDII fibroblast cells or patient's lymphocytes or monocytes resulted in uptake of the rhGAA and reversal of the enzymatic defect. Mannose-6-phosphate in the media blocked uptake. GAA -/- mice were treated with the rhGAA at 1 mg/kg, which resulted in heterozygous levels of GAA in tissues, most notably skeletal muscle, heart and diaphragm after two infusions. More importantly, after multiple infusions, hind, and fore-limb muscle weakness was reversed. This rhGAA would be ideal for enzyme replacement therapy in GSD II.

Identification of two subtypes of infantile acid maltase deficiency.

Infantile patients with acid maltase deficiency have severe hypertrophic cardiomyopathy, left ventricular outflow obstruction, and generalized muscle weakness and die before 1 year of age. We identified 12 infants with acid maltase deficiency who had a similar clinical presentation but less severe cardiomyopathy and absence of left ventricular outflow obstruction, and 9 of 12 had longer survival with assisted ventilation and supplemental intubation.

A preliminary study of growth hormone therapy for Crohn's disease.

BACKGROUND: Crohn's disease is a chronic inflammatory disorder of the bowel. In a preliminary study, we evaluated whether the administration of growth hormone (somatropin) as well as a high-protein diet would ameliorate the symptoms of the disease. METHODS: We randomly assigned 37 adults with moderate-to-severe active Crohn's disease to four months of self-administered injections of growth hormone (loading dose, 5 mg per day subcutaneously for one week, followed by a maintenance dose of 1.5 mg per day) or placebo. We instructed all patients to increase their protein intake to at least 2 g per kilogram of body weight per day. Patients continued to be treated by their usual physicians and to receive other medications for Crohn's disease. The primary end point was the change in scores on the Crohn's Disease Activity Index from base line to month 4. Scores can range from 0 to 600, with higher scores indicating more disease activity. RESULTS: At base line, the mean (+/-SD) score on the Crohn's Disease Activity Index was somewhat higher among the 19 patients in the growth hormone group than among the 18 patients in the placebo group (287+/-134 vs. 213+/-120, P=0.09). Three patients in the placebo group withdrew before their first follow-up visit and were not included in the data analysis. At four months, the Crohn's Disease Activity Index score had decreased by a mean of 143+/-144 points in the growth hormone group, as compared with a decrease of 19+/-63 points in the placebo group (P=0.004). Side effects in the growth hormone group included edema (in 10 patients) and headache (in 5) and usually resolved within the first month of treatment. CONCLUSIONS: Our preliminary study suggests that growth hormone may be a beneficial treatment for patients with Crohn's disease.

Early onset of diabetes mellitus associated with the mitochondrial DNA T14709C point mutation: patient report and literature review.

We report a family in which a mother and son were affected with diabetes mellitus and myopathy characterized by ragged red fibers and suggestive of mitochondrial disease. Mitochondrial DNA (mtDNA) analysis of DNA isolated from peripheral blood showed a T-->C point mutation at nucleotide position 14709, in the transfer RNA gene for glutamic acid. We review the association of diabetes and mtDNA mutations. This child's case is unusual because of the early onset of diabetes, which is more typical of mtDNA deletions.

Insulin-like growth factor-I and high protein diet decrease calpain-mediated proteolysis in murine muscular dystrophy.

In muscular dystrophy (MD) the imbalance between muscle protein synthesis and degradation may be an important factor leading to muscle wasting. The three major pathways of muscle proteolysis identified in skeletal muscle are: the lysosomal cathepsin pathway, the calcium-dependent calpain pathway, and the ATP-dependent ubiquitin pathway. Insulin-like growth factor I (IGF-I) and a high-protein diet (HPD) have been shown to reduce proteolysis in skeletal muscle. We examined the effect of 6 weeks of recombinant human IGF-I (rhIGF-I) alone or in combination with HPD treatment on the proteolytic pathways in skeletal muscle of 129 ReJ dystrophic (dy) mice. (A group of normal (Norm) nondystrophic (129 J) mice were included as controls). Untreated dy mice exhibited increased net proteolysis (P < 0.05), elevated net calpain activity (P < 0.01), and increased ubiquitin levels when compared to control mice (P < 0.05). Our evidence suggests that HPD and rhIGF-I decrease proteolysis in the 129 ReJ dy mouse. This effect appears attributable, at least in part, to reduced calpain-mediated myofibrillar breakdown (P < 0.05) due to decreased calpain autolysis or increased calpastatin levels. In contrast to calpain, cathepsin B activity was increased in HPD and rhIGF-I + HPD-treated dy muscle (P < 0.05) and unaltered in the rhIGF-I treated animals. Levels of free and protein-conjugated ubiquitin were also increased in rhIGF-I, and rhIGF-I + HPD treated dyanimals (P < 0.05). The amelioration of muscle wasting in the 129 ReJ dy model by HPD and/or rhIGF-I may have potential implications in the treatment of human MD.

The role of dietary zinc in modifying the onset and severity of spontaneous diabetes in the BB Wistar rat.

The goal of this study was to determine whether zinc supplementation in the diet of diabetes-prone BB Wistar rats will delay or prevent the onset of overt diabetes. Male Wistar BB rats were fed diets containing either 1000 ppm (HZ), 50 ppm (NZ), or 1 ppm zinc (LZ) starting at 30 days of age. Non-diabetes-prone rats were fed NZ and designated as controls (NORM). Beginning at 60 days, the rats were checked for glycosuria and, if positive, were given an i.p. glucose tolerance test (IPGTT). All remaining animals underwent an IPGTT at 100 days and were sacrificed. At 90 days of age HZ rats had a lower incidence of diabetes (19%) than NZ (53%) or LZ (44%) animals (P < 0.015). By age 100 days, for the HZ group, there was a 60% reduction in the number of expected overt diabetic rats. HZ animals also had higher concentrations of both pancreatic and serum insulin and exhibited lower serum glucose and triglycerides. Immunohistochemistry of HZ rats was clearly different from NZ rats and showed evidence of nearly normal pancreatic endocrine activity. Data indicate that dietary treatment of diabetes-prone BB Wistar rats with zinc appears to be an effective approach for delaying or preventing the onset of diabetes in genetically predisposed rodents. This finding may suggest further experimental studies regarding dietary means for preservation of pancreatic function.

Beneficial effect of diazoxide in obese hyperinsulinemic adults.

UNLABELLED: Hyperinsulinemia, insulin resistance, and increased adipose tissue are hallmarks of the obesity state in both humans and experimental animals. The role of hyperinsulinemia as a possible preceding event in the development of obesity has been proposed. We previously demonstrated that administration of diazoxide (DZ), an inhibitor of insulin secretion, to obese hyperinsulinemic Zucker rats resulted in less weight gain, enhanced insulin sensitivity, and improved glucose tolerance. Assuming that hyperinsulinemia plays a major role in the development of human obesity, then its reversal should have therapeutic potential. To test this hypothesis, we conducted a randomized placebo-controlled trial in 24 hyperinsulinemic adults [body mass index (BMI) > 30 kg/m2]. All subjects were placed on a low-calorie (1260 for females and 1570 for males) Optifast (Sandoz, Minneapolis, MN) diet. After an initial 1-week lead-in period, 12 subjects (mean +/- SE for age and BMI, 31 +/- 1 and 40 +/- 2, respectively) received DZ (2 mg/kg BW.day; maximum, 200 mg/day, divided into 3 doses) for 8 weeks; and 12 subjects (mean +/- SE for age an BMI, 28 +/- 1 and 43 +/- 1, respectively) received placebo. Compared with the placebo group, DZ subjects had greater weight loss (9.5 +/- 0.69% vs. 4.6 +/- 0.61%, P < 0.001), greater decrease in body fat (P < 0.01), greater increase in fat-free mass to body fat ratio (P < 0.01), and greater attenuation of acute insulin response to glucose (P < 0.01). However, there was no significant difference in insulin sensitivity and glucose effectiveness, as determined by the insulin-modified i.v. glucose tolerance test (Bergman's minimal model) and no significant difference in glycohemoglobin values. CONCLUSION: 8 weeks treatment with DZ had a significant antiobesity effect in hyperinsulinemic obese adults without inducing hyperglycemia.

Metabolic and structural effects of insulin-like growth factor-I and high-protein diet on dystrophic hamster skeletal muscle.

In muscular dystrophy (MD) there is an imbalance between muscle protein synthesis and protein degradation, which results in a net muscle catabolism, along with muscle wasting and weakness. Using a dystrophic hamster model (BIO 53.58), we examined the chronic (8 weeks) effects of two factors that may enhance muscle protein synthesis and inhibit protein degradation, namely, insulin-like growth factor-I (rhIGF-I) and high-protein diet (HPD). Protein synthesis was determined by measuring the incorporation of 14C phenylalanine into perfused leg muscle, while protein degradation was calculated from the release of tyrosine from the same perfused muscle. Urinary 3-methylhistidine excretion was used as an indicator of myofibrillar degradation. Treatment of dystrophic hamsters with rhIGF-I, HPD, or a combination of the two for 8 weeks resulted in significant decreases in total and myofibrillar degradation when compared with untreated dystrophic animals (P < 0.05) but had minimal effects on protein synthesis. Significant morphologic improvements (P < 0.05), including a normalization and greater uniformity of muscle fibers, were also seen in rhIGF-I- and rhIGF-I + HPD-treated animals. rhIGF-I and HPD were effective in reducing the excessive proteolysis seen in dystrophic muscle, and this reduced proteolysis resulted in improvement of muscle morphology.

Novel mutation in the mitochondrial DNA tRNA glycine gene associated with sudden unexpected death.

We describe an A-to-G transition at nucleotide 10044 in the tRNA(Gly) gene of mitochondrial DNA in a sibship in which the proband died at age 8 years after a severe encephalopathy, a brother died of sudden and unexpected death, and the other six siblings had a combination of symptoms, including apparent life-threatening events and gastroesophageal reflux. This novel mutation was very abundant (> 90%) in liver and muscle of the proband and in several tissues, including blood, from his affected siblings (range 91-99%) but was less abundant in blood from the asymptomatic mother (88%) and maternal grandmother (85%). Our findings further enlarge the spectrum of clinical presentations associated with mitochondrial DNA mutations.

Metabolic and clinical response to recombinant human insulin-like growth factor I in myotonic dystrophy--a clinical research center study.

Muscle weakness and wasting in myotonic dystrophy (MyD) are believed to be due to a decrease in muscle protein synthesis, secondary to insulin resistance. A 4-month, randomized, double blind, placebo-controlled trial was undertaken to assess whether recombinant human insulin-like growth factor I (rhIGF-I) may overcome the insulin resistance. Patients received either 5 mg rhIGF-I (n = 7) or placebo (n = 9), sc, twice daily. Glucose metabolism was assessed by stable label iv glucose tolerance test, amino acid metabolism by L-[13C] leucine turnover, body composition by dual energy x-ray absorptiometry and N excretion, and muscle response by manual muscle strength and neuromuscular function. In the treated group, the insulin sensitivity index, insulin action, and glucose disposal all increased (P < 0.05). Leucine flux and leucine incorporation into protein increased (P < 0.05), and the rate of leucine oxidation to leucine turnover decreased (P < 0.05), findings indicative of increased protein synthesis. Body weight and lean body mass increased, whereas percent body fat decreased (P < 0.05). An increase in manual muscle strength of 0.42 +/- 0.30 (P < 0.02) and in neuromuscular function of 17.5 +/- 11.7 (P < 0.02) occurred in the four patients who received a rhIGF-I dose greater than 70 micrograms/kg, whereas a more modest response occurred in the three patients who received a dose less than 70 micrograms/kg. Two patients showed dramatic improvement. Long term rhIGF-I therapy appears to cause metabolic and muscle improvement in optimally treated MyD patients.

Effect of insulin-like growth factor I in murine muscular dystrophy.

In muscular dystrophy there is an imbalance between muscle protein synthesis and protein degradation, resulting in net muscle catabolism and progressive muscle weakness and wasting. Both insulin and insulin-like growth factor I (IGF-I) are known to have an anabolic effect on skeletal muscle, which is believed to be enhanced in the presence of elevated concentrations of amino acids. We examined the effects of 4-week administration of recombinant human IGF-I (rhIGF-I), both alone and supplemented with a high protein diet (HPD), on muscle metabolism, morphology, and function in the 129 ReJ dystrophic mouse. rhIGF-I significantly reduced muscle protein degradation (P < 0.001), increased muscle protein content (P < 0.05), decreased fiber area variability (P < 0.01), and increased hind limb utilization (P < 0.01). Supplementation of rhIGF-I therapy with a HPD resulted in a significant increase in muscle protein synthesis (P < 0.05) in addition to a further increase in the above parameters. We conclude that rhIGF-I causes an improvement in muscle metabolism, morphology, and function in dystrophic mice, and this effect is further enhanced by the presence of a HPD.

High protein diet has beneficial effects in murine muscular dystrophy.

In normal muscle there is a delicate balance between muscle protein synthesis and protein degradation. It is believed that this balance is disturbed in muscular dystrophy (MD) by decreased muscle protein synthesis and/or increased muscle protein degradation, resulting in net catabolism. In an attempt to reduce or reverse this catabolism, a high protein diet (HPD, 50% protein) was fed to dystrophic mice (129/ReJ dy) for 4 wk. The effects on muscle biochemistry, muscle function and muscle morphology were compared with those in dystrophic mice fed a normal diet (NPD, 20% protein) and in nondystrophic mice (NORM) also fed the 20% protein diet. Compared with NORM mice, NPD mice demonstrated greater rates of muscle protein synthesis (P < 0.05) as measured by the incorporation of labeled phenylalanine into muscle, greater protein degradation (P < 0.01) as measured by urinary 3-methylhistidine excretion, and lower muscle protein concentration (P < 0.01). When dystrophic mice were fed HPD for 4 wk, protein degradation was lower (P < 0.01) and muscle protein concentration greater (P < 0.01) than in NPD mice. These biochemical improvements were accompanied by greater morphological uniformity of muscle fibers, higher volume density of muscle fibers per unit area of muscle (P < 0.01), and lower shape factor (P < 0.01). Functionally, HPD led to improved muscle endurance (P < 0.01) and increased hind-limb utilization (P 0.01). We conclude that in murine dystrophy, HPD decreases net muscle catabolism, principally by decreasing muscle protein degradation, resulting in improvement in muscle morphology, strength and function.

Nutrition therapy for hepatic glycogen storage diseases.

Hepatic glycogen storage diseases (GSD) are a group of rare genetic disorders in which glycogen cannot be metabolized to glucose in the liver because of one of a number of possible enzyme deficiencies along the glycogenolytic pathway. Patients with GSD are usually diagnosed in infancy or early childhood with hypoglycemia, hepatomegaly, poor physical growth, and a deranged biochemical profile. Dietary therapies have been devised to use the available alternative metabolic pathways to compensate for disturbed glycogenolysis in GSD I (glucose-6-phosphatase deficiency), GSD III (debrancher enzyme deficiency), GSD VI (phosphorylase deficiency, which is less common), GSD IX (phosphorylase kinase deficiency), and GSD IV (brancher enzyme deficiency). In GSD I, glucose-6-phosphate cannot be dephosphorylated to free glucose. Managing this condition entails overnight continuous gastric high-carbohydrate feedings; frequent daytime feedings with energy distributed as 65% carbohydrate, 10% to 15% protein, and 25% fat; and supplements of uncooked cornstarch. In GSD III, though glycogenolysis is impeded, gluconeogenesis is enhanced to help maintain endogenous glucose production. In contrast to treatment for GSD I, advocated treatment for GSD III comprises frequent high-protein feedings during the day and a high-protein snack at night; energy is distributed as 45% carbohydrate, 25% protein, and 30% fat. Patients with GSD IV, VI, and IX have benefited from high-protein diets similar to that recommended for patients with GSD III.

Modification of insulin resistance by diazoxide in obese Zucker rats.

Hyperinsulinism, insulin resistance, and decreased number of insulin receptors are characteristic of obesity in both humans and experimental animals. To assess the role of insulin in developing obesity, diazoxide (DZ), an inhibitor of glucose-stimulated insulin secretion, was administered for 8 weeks to 7-week-old female Zucker rats in two concentrations, 50 mg/kg.day (LD-DZ), and 100 mg/kg.day (HD-DZ). The obese and lean rats were divided into three subgroups: diazoxide (DZ), pair-fed (PF), and control (C) groups (n = 6 rats/subgroup-genotype). Diazoxide-treated obese and lean animals showed significantly lower postabsorptive plasma insulin concentrations (P < 0.005) than their respective obese and lean PF and C subgroups. HD-DZ obese rats consumed more calories (P < 0.001), yet gained less weight (P < 0.05) than PF and C rats. The plasma glucose concentrations in the postabsorptive state and during glucose tolerance tests in HD-DZ obese rats were significantly lower than those in PF and C rats (P < 0.01) despite a decrease in their plasma insulin concentrations (P < 0.01), whereas HD-DZ lean rats displayed a diabetic response (P < 0.01). The adipocyte-specific insulin receptor binding was dose-dependently increased in both lean and obese DZ animals (P < 0.01). DZ had a dual effect on insulin metabolism; it decreased insulin secretion and increased insulin receptor binding. This dual effect was associated with improved glucose tolerance and a decrease in weight gain in obese rats.

Clinical response of alopecia, trichorrhexis nodosa, and dry, scaly skin to zinc supplementation.

Two unrelated patients had dry brittle hair, alopecia, trichorrhexis nodosa, dry scaly skin, pigment dyschromia, short stature, and neurosecretory growth hormone deficiency. By means of the zinc tolerance test, patient 1 was shown to have zinc deficiency, whereas no clear zinc deficiency could be demonstrated in patient 2. In both patients, hair and the skin abnormalities responded to oral zinc therapy.

Evaluation of the lumbar spine in patients with glycogen storage disease: CT demonstration of patterns of paraspinal muscle atrophy.

CT studies of the lumbar spine were performed in 19 patients with glycogen storage disease. Nine of 10 patients with McArdle's disease and seven of nine patients with acid maltase deficiency demonstrated posterior paraspinal muscle atrophy out of proportion to their ages. In addition, the psoas muscles were spared in all 10 patients with McArdle's disease and were involved with atrophy in seven of the nine patients with acid maltase deficiency. We conclude that when patients with low back pain-or asymptomatic patients-demonstrate otherwise unexplained atrophy of the paraspinal muscles the diagnosis of glycogen storage disease should be considered. Furthermore, when the psoas muscles are spared, the specific diagnosis of McArdle's disease is suggested.