Biomedical subjects

E Holme

Publications and source records attributed to E Holme.

At least 55 records · Page 3Linked to original sources

PubMed1996

Pivalic acid-induced carnitine deficiency and physical exercise in humans.

To study the effect of carnitine depletion on physical working capacity, healthy subjects were administered pivaloyl-conjugated antibiotics for 54 days. The mean carnitine concentration in serum decreased from 35.0 to 3.5 mmicromol/L, and in muscle from 10 to 4.3 micromol/g noncollagen protein (NCP). Exercise tests were performed before and after 54 days' administration of the drug. At submaximal exercise, there was a slight increase in the concentration of 3-hydroxybutyrate in serum, presumably caused by decreased fatty acid oxidation in the liver. There was also a decreased consumption of muscle glycogen, indicating decreased glycolysis in the skeletal muscle. The muscle presumably had enough energy available, since there was no significant decrease in the concentration of adenosine triphosphate (ATP) and creatine phosphate during exercise. The work at maximal oxygen uptake (VO2max) and the maximal heart rate were reduced. Since VO2max is considered dependent on heart function, carnitine depletion seemed to affect cardiac function.

Adolescent↗

PubMed1996

IgA class anticardiolipin antibodies in cutaneous leukocytoclastic vasculitis.

BACKGROUND: Autoantibodies may be detected in the serum of some patients with cutaneous leukocytoclastic vasculitis. We have previously reported the presence of IgA anticardiolipin antibodies (ACAs) in one patient with leukocytoclastic vasculitis associated with IgA nephropathy. OBJECTIVE: Our purpose was to determine the prevalence of IgA ACAs in unselected groups of patients with cutaneous vasculitis, IgA nephropathy, and Henoch-Schönlein purpura. METHODS: Thirty patients (10 each with cutaneous vasculitis, IgA nephropathy, and Henoch-Schönlein purpura) and 31 healthy control subjects were studied. ACA titers were measured by a standardized enzyme-linked immunosorbent assay. RESULTS: ACAs restricted to the IgA isotype were present in 6 of 10 patients with cutaneous leukocytoclastic vasculitis. IgA ACA levels were significantly higher in these patients than in the control subjects. The presence of IgA ACAs did not correlate with disease severity or involvement of other organs and persisted after resolution of the vasculitis in most patients. In five of the six patients with IgA ACAs, drugs were implicated in the pathogenesis of the vasculitis. By contrast, ACAs were present in only a minority of children with Henoch-Schönlein purpura and adults with IgA nephropathy and were not restricted to the IgA isotype. CONCLUSION: We have demonstrated a clear association between IgA ACAs and cutaneous leukocytoclastic vasculitis. The absence of IgA ACAs in Henoch-Schönlein purpura argues against their being an epiphenomenon in vasculitis.

Adult↗

PubMed1996

Glycerol kinase deficiency in two brothers with and without clinical manifestations.

We report two brothers with glycerol kinase deficiency (GKD). The older brother had serious clinical symptoms, mental and growth retardation, abnormal skeleton, spontaneous fractures and premature loss of abnormal teeth. He and his mother had low serum phosphate levels. He had elevated serum and urine glycerol levels and GKD was found in cultured fibroblasts. Prenatal diagnosis was performed in the second pregnancy. Glycerol kinase activity was considered normal in a chorionic villus sample of the foetus. After birth, it was found that the boy had elevated serum and urine glycerol levels. Enzymatic analysis in cultured fibroblasts revealed that this boy also had GKD, in spite of having no expression of the disease. Chromosomal analyses in the parents and both boys were normal. Major rearrangements or deletions were not detected in molecular studies of DNA from the two brothers. The hybridisation pattern was normal and no allelic loss was observed.

Abnormalities, Multiple↗

PubMed1995

Inheritance and expression of mitochondrial DNA point mutations.

An important feature of the mitochondrial genom is the occurrence of heteroplasmy and the possibility for transmission to the offspring of various proportions of wild-type and mutated mtDNA. We have investigated the proportion of the tRNALys A8344G mutation, the tRNALeu(UUR) A3243G mutation, and the ATPase 6 T8993G mutation in patients with MERRF, MELAS, and Leigh's syndrome and their maternal relatives. The level of mutated mtDNA in the offspring of carriers of the tRNALys mutation is correlated to the level in lymphocytes in the mother and seems to be transmitted by an essentially random mechanism where only a few mtDNA copies are founders of the mitochondrial genom in the offspring and the probability that the mutation is not transmitted to the offspring is high when the mothers carriers predominantly wild-type mtDNA. However, we found age-related differences in the distribution of mutated mtDNA in carriers of the tRNALys and tRNALeu mutations, which have to be considered before levels of mutated mtDNA are used for prediction of prognosis and transmission of a disorder.

Adolescent↗

PubMed1995

Pathogenetic aspects of the A8344G mutation of mitochondrial DNA associated with MERRF syndrome and multiple symmetric lipomas.

Myoclonus epilepsy and ragged-red fibers syndrome (MERRF) is caused by a heteroplasmic mutation at nucleotide 8344 (A8344G) of the tRNA(Lys) gene of mitochondrial DNA (mtDNA). This mutation impairs mitochondrial protein synthesis and causes a respiratory chain dysfunction. The risk for transmission of the A8344G mutation from mother to child is dependent on the levels of mutated mtDNA in the mother and above a threshold level of 35-40% the mutation is transmitted to all children. The progression of symptoms in MERRF can be explained by a gene dosage effect with accumulation over time of mutated mtDNA. High levels of mutated mtDNA, ultrastructurally abnormal mitochondria, and a clonal deletion on chromosome 6 are found in lipomas associated with MERRF. These findings indicate that there is a respiratory chain dysfunction in the lipomas and that lipomas may be a manifestation of the A8344G mutation.

Child↗

PubMed1995

Effect of short-term treatment with pivalic acid containing antibiotics on serum carnitine concentration--a risk irrespective of age.

Treatment with pivalic acid containing prodrugs has been shown to cause carnitine depletion by loss of pivaloyl carnitine in urine. A 7-day standard pivmecillinam treatment of adults lead to a marked decrease of the free serum carnitine concentration (44.6 to 12.9 mumol/liter), whereas no change was seen in those given norfloxacine (40.0 to 40.5 mumol/liter). In some patients irrespective of age the free serum carnitine concentration was decreased to levels (around 10 mumol/liter) at which an impaired ketone-body production may occur. Therefore, there is reason for cautious use of this type of drug irrespective of the age of the patients.

Adolescent↗

PubMed1995

De novo mutation in the mitochondrial ATP synthase subunit 6 gene (T8993G) with rapid segregation resulting in Leigh syndrome in the offspring.

The mutation in the mitochondrial ATP synthase subunit 6 gene (ATP6 T8993G) was identified in a male infant who died at age 15 months of Leigh syndrome. He had 94% mutated mitochondrial DNA (mtDNA) in muscle and 92% in lymphocytes. His mother was healthy but had 37% mutated mtDNA in muscle and 38% in lymphocytes. The proband's brother, who was also healthy, had 44% mutated mtDNA in lymphocytes. No mutated mtDNA was detected in muscle and lymphocytes from the maternal grandmother of the proband or in lymphocytes from 15 other maternal relatives, showing that the first carrier of the ATP6 T8993G mutation in this family was the mother of the proband. This study shows that this point mutation may occur at substantial levels in a carrier of a de novo mutation and rapid segregation with high levels of mutated mtDNA causing neurodegenerative disease may occur in the second generation.

2,4-Dinitrophenol↗

PubMed1995

Tissue distribution and disease manifestations of the tRNA(Lys) A-->G(8344) mitochondrial DNA mutation in a case of myoclonus epilepsy and ragged red fibres.

This man with myoclonus epilepsy and ragged red fibres (MERRF) syndrome due to the tRNA(Lys) A-->G(8344) mutation of mitochondrial DNA (mtDNA) died of bronchopneumonia at 18 years of age. He had progressive clinical symptoms from 6 months of age manifesting as ataxia, myoclonic seizures, and muscle weakness. A post-mortem examination revealed 91-99% mutated mtDNA in all 32 examined tissue samples, including various organs and different brain regions. The brain appeared without macroscopic changes, but microscopic examination showed degeneration with loss of nerve cells and gliosis affecting the globus pallidus, substantia nigra, red nucleus, dentate nucleus, inferior olivary nucleus, cerebellar cortex, and the spinal cord. Skeletal muscle showed cytochrome c oxidase deficient muscle fibres with proliferation of mitochondria. In addition to pathological changes of muscle and brain there were few morphological changes that could be attributed to his mitochondrial disease. These data support the concept that in patients with the tRNA(Lys) A-->G(8344) mutation who are manifesting disease there are high levels of mutated mtDNA in all tissues, but only some tissues and brain regions are vulnerable.

Adolescent↗

PubMed1995

Atypical presentation of multisystem disorders in two girls with mitochondrial DNA deletions.

UNLABELLED: We describe two girls with atypical presentations of multisystem disorders due to deletions in mitochondrial DNA (mtDNA). One presented with painful carpopedal spasms due to hypoparathyroidism at the age of 4 years. The disease was rapidly progressive with development of truncal and limb ataxia, spastic paraparesis, muscle weakness and wasting, pigmentary retinal degeneration and sensorineural hearing loss. She had short stature and vitiligo patches, hirsutism, anaemia, diabetes mellitus and exocrine pancreatic dysfunction. The other girl presented at the age of 6 years with polydipsia, polyuria and fatigue due to renal tubular dysfunction. The disease was insidiously progressive with poor growth and development of sensorineural hearing loss, muscle weakness and truncal and limb ataxia. Morphological, enzyme histochemical and biochemical investigations indicated mitochondrial dysfunction of skeletal muscle, liver and kidney in one patient and of skeletal muscle and liver in the other. Both patients had large proportions of mtDNA molecules with deletion in liver, kidney, skeletal muscle and blood cells. CONCLUSION: It may be concluded that symptoms from several different organs may be the first manifestation of a mtDNA deletion disorder.

Blotting, Southern↗

PubMed1995

Mitochondrial DNA deletions in muscle fibers in inclusion body myositis.

Inclusion body myositis (IBM) is an autoimmune, inflammatory myopathy where morphological changes of muscle, including ragged red fibers, have indicated mitochondrial dysfunction in some muscle fibers. In this study enzyme histochemical analysis showed that cytochrome c oxidase (COX)-deficient muscle fibers were present at a frequency ranging from 0.5 to 5% of the muscle fibers in a series of 20 IBM patients. In age-matched controls, only occasional COX-deficient muscle fibers were present. Polymerase chain reaction (PCR) analysis of DNA extracted from muscle tissue of the IBM patients showed multiple mtDNA deletions. PCR analysis of isolated, single muscle fibers showed presence of mtDNA with only one type of deletion and deficiency of wild-type mtDNA in each COX-deficient muscle fiber. This finding was supported by results from in situ hybridization using different mtDNA probes on consecutive sections. A 5 kb deletion was identified in all 20 IBM patients. DNA sequencing of the breakpoint region showed that this deletion was the so-called "common deletion." Most but not all of the investigated deletion breakpoints were flanked by direct repeats. COX-deficient fibers were more frequent among fibers with positive immunostaining with antibodies directed toward a regeneration marker, the Leu-19 antigen, than in the entire fiber population. These results show that COX deficiency in muscle fiber segments in IBM is associated with deletions of mtDNA. Clonal expansion of mtDNA with deletions may take place in regenerating muscle fibers following segmental necrosis.

Adult↗

PubMed1995

Diagnosis and management of tyrosinemia type I.

Hereditary tyrosinemia type I (HTI) (MIM 276700) is an autosomal recessive disorder caused by deficiency of fumarylacetoacetase (EC 3.7.1.2), which is the last enzyme in the tyrosine degradation pathway. The enzyme block causes accumulation of toxic metabolites in the liver and kidneys, which are the organs where tyrosine is mainly degraded. The disorder is characterized by severe liver disease, which either causes liver failure in infancy or may take a more protracted course, with death often occurring during childhood or adolescence because of hepatoma development. Treatment with a diet restricted in phenylalanine nd tyrosine does not prevent progression of the liver disease and development of hepatocellular carcinoma. Liver transplantation was previously the only option for these patients. Important achievements from metabolic and molecular biology studies of the disease include a new treatment for patients with HTI using an enzyme inhibitor, detection of self-induced correction of the genetic defect in regenerative liver nodules in HTI patients, identification and development of useful animal models for HTI, and studies of the molecular genetics of HTI. These advances will have great implications for our understanding of pathogenetic mechanisms, which is the basis for improved diagnostic methods and improved treatment of patients with HTI.

4-Hydroxyphenylpyruvate Dioxygenase↗

PubMed1995

Use of primary cultures and continuous cell lines to study effects on astrocytic regulatory functions.

1. Current opinions on the mechanisms for glutamate-mediated neurotoxicity are reviewed. The protective role of astrocytic high-affinity glutamate transport is also discussed. 2. Low-density seeding of primary astrocytes from rat hemispheres was found to result in the development of reactive-like astrocytes. Typical glial signs of amyotrophic lateral sclerosis (ALS) could not be induced in astrocyte cultures by serum from ALS-patients. 3. Glutamate (100 mumol/L) was found to induce an increase in respiratory activity in primary cultures of astrocytes. This stimulation appeared to be related to the co-transport of Na2+ with glutamate and a resulting activation of Na2+/K(+)-ATPase. Both basal respiration and glutamate-stimulated oxygen consumption was inhibited by organic solvents. 4. Preliminary results show that heavy metals cause an increase in the mitochondrial DNA content at concentrations that have no effect on growth rate or morphology in a glial cell line. This increase was accompanied by an inhibition of oxygen consumption and an increased production of lactate at unaltered ATP levels.

Amyotrophic Lateral Sclerosis↗

PubMed1995

Ekbom's syndrome of photomyoclonus, cerebellar ataxia and cervical lipoma is associated with the tRNA(Lys) A8344G mutation in mitochondrial DNA.

We have investigated nine maternal offsprings to patients with a hereditary syndrome of cerebellar ataxia, photomyoclonus, skeletal deformities and lipoma, originally described by Ekbom. The nine family members underwent a thorough neurological examination, neurophysiological investigations and molecular genetic analysis of mtDNA from lymphocytes and muscle. Clinical examination showed a partial syndrome in one relative and minor signs and symptoms in three additional offsprings. We found the heteroplasmic tRNALys A8344G point mutation in mtDNA in all investigated maternal offsprings. The fraction of mutated mtDNA ranged from 33 to 87% in lymphocytes and from 59 to 92% in muscle tissue. Analysis of mtDNA from a lipoma showed a high level (96%) of the tRNALys A8344G mutation. We conclude that Ekbom's syndrome is a mitochondrial encephalomyopathy associated with the same heteroplasmic tRNA mutation as seen in myoclonus epilepsy with ragged-red fiber (MERRF) syndrome.

Adult↗

PubMed1995

Transient reduction of human left ventricular mass in carnitine depletion induced by antibiotics containing pivalic acid.

OBJECTIVE: To study the effect of induced carnitine depletion on myocardial structure and function. SUBJECTS AND DESIGN: 7 healthy adult volunteers given 1200 mg pivmecillinam per day for 7-8 weeks were studied by echocardiography before and after 7-8 weeks of treatment and a 15 months follow up after the treatment period. SETTING: Teaching hospital. MAIN OUTCOME MEASURES: Carnitine concentration in serum, urine, and muscle and echocardiographic measurements. RESULTS: After 7-8 weeks of treatment the median free serum carnitine concentration was reduced to 7% and the median total muscle carnitine concentration to 46% of the pretreatment levels. The median diastolic interventricular septum thickness decreased by 14% (mean 26%, P = 0.028) and the median left ventricular mass by 10% (mean 20%, P = 0.018). Fifteen months later these dimensions had increased but not completely returned to pretreatment values. CONCLUSIONS: Extended treatment with pivalic acid containing antibiotics causes carnitine depletion which may lead to changes in cardiac structure.

Adolescent↗

PubMed1994

Low levels of mitochondrial transcription factor A in mitochondrial DNA depletion.

Low levels of mitochondrial transcription factor A (mtTFA) were found in muscle fibers with mitochondrial DNA (mtDNA) depletion in a child with fatal mitochondrial myopathy and also in a human cell line lacking mtDNA. High levels of this transcriptional activator were found in muscle fibers with mtDNA accumulation in two patients with single mtDNA deletions. This is the first example of a nuclear gene product that varies with the levels of mtDNA in humans. Since transcription is required for the replication of mtDNA, it is possible that mtTFA may be involved in the regulation of mtDNA replication.

Child, Preschool↗

PubMed1994

Automatic sequencing of mitochondrial tRNA genes in patients with mitochondrial encephalomyopathy.

We have investigated nine children with infantile onset of mitochondrial myopathy and two adults with myoclonus epilepsy and ragged-red fibers (MERRF) and chronic progressive external ophthalmoplegia (CPEO), respectively. These patients lacked any of the previously known pathogenic tRNA mutations. Southern blot analysis of muscle mtDNA revealed no deletions. The tRNA genes of muscle mtDNA were sequenced. Restriction enzyme analysis of PCR fragments was performed to verify the presence of the mutations identified by automatic sequencing. Several tRNA mutations were found, but they were all homoplasmic. Furthermore, the mutations were either present in controls or did not change nucleotides conserved between species. This strongly suggests that none of the tRNA mutations identified in the 11 patients with mitochondrial encephalomyopathy was pathogenic. It can thus be concluded that mitochondrial tRNA mutations and mtDNA deletions probably are an infrequent cause of mitochondrial disorders in infants. Patients with MERRF and CPEO may lack both pathogenic point mutations of tRNA genes and deletions of mtDNA.

Adult↗

PubMed1994

Impaired ketogenesis in carnitine depletion caused by short-term administration of pivalic acid prodrug.

Long-term treatment with pivalic acid prodrug results in impaired ketone-body production. Therefore, it was of interest to investigate whether short-term treatment had any influence on the fatty acid oxidation. In this study six healthy males were given 1200 mg per day of pivmecillinam for 12 days to induce carnitine deficiency. The concentration of free carnitine in serum was reduced from a mean of 42.8 mumol/liter (range, 31-48) to 11.6 mumol/liter (range, 7.0-24), but the muscle carnitine concentration was not reduced. A 36-h fasting test was performed before and after drug administration to study the effect on ketone-body production. After treatment, the two subjects with the lowest level of serum free carnitine at the end of the fasting period had impaired ketogenesis. This indicates a carnitine deficiency in the liver which was reflected in the free carnitine concentration for by mobilization of muscle carnitine. We conclude that there is a substantial risk to develop carnitine deficiency and impaired fatty acid oxidation in the liver during short-term treatment with drugs conjugated with pivalic acid.

Adult↗

PubMed1993

Recurrent metabolic decompensation in profound carnitine palmitoyltransferase II deficiency.

A 3-year-old boy had recurrent episodes of lethargy, encephalopathy, and hepatomegaly accompanied by hypoglycemia, elevated liver aminotransferase and creatine kinase values, and nonketotic dicarboxylic aciduria; the serum carnitine level was moderately reduced. Carnitine palmitoyltransferase II activity was decreased in lymphocytes and fibroblasts. Therapy with L-carnitine and a diet low in long-chain triglycerides did not prevent recurrent episodes.

Carnitine O-Palmitoyltransferase↗