Pearson's marrow-pancreas syndrome. A multisystem mitochondrial disorder in infancy

Pearson's marrow-pancreas syndrome (McKusick No. 26056) is a fatal disorder of hitherto unknown etiology involving the hematopoietic system, exocrine pancreas, liver, and kidneys. The observation of high lactate/pyruvate molar ratios in plasma and abnormal oxidative phosphorylation in lymphocytes led us to postulate that Pearson's syndrome belongs to the group of mitochondrial cytopathies. Since rearrangements of the mitochondrial genome between direct DNA repeats were consistently found in all tissues tested, our results show that this disease is in fact a multisystem mitochondrial disorder, as suggested by the clinical course of the patients. Based on these observations, we would suggest giving consideration to the hypothesis of a defect of oxidative phosphorylation in elucidating the origin of other syndromes, especially those associated with an abnormal oxidoreduction status in plasma.

Mutations in the fukutin-related protein gene (FKRP) identify limb girdle muscular dystrophy 2I as a milder allelic variant of congenital muscular dystrophy MDC1C

The limb girdle and congenital muscular dystrophies (LGMD and CMD) are characterized by skeletal muscle weakness and dystrophic muscle changes. The onset of symptoms in CMD is within the first few months of life, whereas in LGMD they can occur in late childhood, adolescence or adult life. We have recently demonstrated that the fukutin-related protein gene (FKRP) is mutated in a severe form of CMD (MDC1C), characterized by the inability to walk, leg muscle hypertrophy and a secondary deficiency of laminin alpha2 and alpha-dystroglycan. Both MDC1C and LGMD2I map to an identical region on chromosome 19q13.3. To investigate whether these are allelic disorders, we undertook mutation analysis of FKRP in 25 potential LGMD2I families, including some with a severe and early onset phenotype. Mutations were identified in individuals from 17 families. A variable reduction of alpha-dystroglycan expression was observed in the skeletal muscle biopsy of all individuals studied. In addition, several cases showed a deficiency of laminin alpha2 either by immunocytochemistry or western blotting. Unexpectedly, affected individuals from 15 families had an identical C826A (Leu276Ileu) mutation, including five that were homozygous for this change. Linkage analysis identified at least two possible haplotypes in linkage disequilibrium with this mutation. Patients with the C826A change had the clinically less severe LGMD2I phenotype, suggesting that this is a less disruptive FKRP mutation than those found in MDC1C. The spectrum of LGMD2I phenotypes ranged from infants with an early presentation and a Duchenne-like disease course including cardiomyopathy, to milder phenotypes compatible with a favourable long-term outcome.

Mutations in SEPN1 cause congenital muscular dystrophy with spinal rigidity and restrictive respiratory syndrome

One form of congenital muscular dystrophy, rigid spine syndrome (MIM 602771), is a rare neuromuscular disorder characterized by early rigidity of the spine and respiratory insufficiency. A locus on 1p35-36 (RSMD1) was recently found to segregate with rigid spine muscular dystrophy 1 (ref. 1). Here we refine the locus and find evidence of linkage disequilibrium associated with SEPN1, which encodes the recently described selenoprotein N (ref. 2). Our identification and analysis of mutations in SEPN1 is the first description of a selenoprotein implicated in a human disease.

Inducible nitric oxide synthase up-regulation in a transgenic mouse model of familial amyotrophic lateral sclerosis

Mutations in copper/zinc superoxide dismutase (SOD1) are associated with a familial form of amyotrophic lateral sclerosis (ALS), and their expression in transgenic mice produces an ALS-like syndrome. Here we show that, during the course of the disease, the spinal cord of transgenic mice expressing mutant SOD1 (mSOD1) is the site not only of a progressive loss of motor neurons, but also of a dramatic gliosis characterized by reactive astrocytes and activated microglial cells. These changes are absent from the spinal cord of age-matched transgenic mice expressing normal SOD1 and of wild-type mice. We also demonstrate that, during the course of the disease, the expression of inducible nitric oxide synthase (iNOS) increases. In both early symptomatic and end-stage transgenic mSOD1 mice, numerous cells with the appearance of glial cells are strongly iNOS-immunoreactive. In addition, iNOS mRNA level and catalytic activity are increased significantly in the spinal cord of these transgenic mSOD1 mice. None of these alterations are seen in the cerebellum of these animals, a region unaffected by mSOD1. Similarly, no up-regulation of iNOS is detected in the spinal cord of age-matched transgenic mice expressing normal SOD1 or of wild-type mice. The time course of the spinal cord gliosis and iNOS up-regulation parallels that of motor neuronal loss in transgenic mSOD1 mice. Neuronal nitric oxide synthase expression is only seen in neurons in the spinal cord of transgenic mSOD1 mice, regardless of the stage of the disease, and of age-matched transgenic mice expressing normal SOD1 and wild-type mice. Collectively, these data suggest that the observed alterations do not initiate the death of motor neurons, but may contribute to the propagation of the neurodegenerative process. Furthermore, the up-regulation of iNOS, which in turn may stimulate the production of nitric oxide, provides further support to the presumed deleterious role of nitric oxide in the pathogenesis of ALS. This observation also suggests that iNOS may represent a valuable target for the development of new therapeutic avenues for ALS.

Expanded CAG repeats in exon 1 of the Huntington's disease gene stimulate dopamine-mediated striatal neuron autophagy and degeneration

Huntington's disease (HD) is caused by an expanded CAG repeat in exon 1 of the gene coding for the huntingtin protein. The cellular pathway by which this mutation induces HD remains unknown, although alterations in protein degradation are involved. To study intrinsic cellular mechanisms linked to the mutation, we examined dissociated postnatally derived cultures of striatal neurons from transgenic mice expressing exon 1 of the human HD gene carrying a CAG repeat expansion. While there was no difference in cell death between wild-type and mutant littermate-derived cultures, the mutant striatal neurons exhibited elevated cell death following a single exposure to a neurotoxic concentration of dopamine. The mutant neurons exposed to dopamine also exhibited lysosome-associated responses including induction of autophagic granules and electron-dense lysosomes. The autophagic/lysosomal compartments co-localized with high levels of oxygen radicals in living neurons, and ubiquitin. The results suggest that the combination of mutant huntingtin and a source of oxyradical stress (provided in this case by dopamine) induces autophagy and may underlie the selective cell death characteristic of HD.

Autosomal dominant syndrome with strokelike episodes and leukoencephalopathy

BACKGROUND AND PURPOSE

We conducted a prospective survey of a family presenting a new syndrome characterized mainly by recurrent strokelike episodes and neuroimaging evidence of leukoencephalopathy.

SUMMARY OF REPORT

Forty-five members of a single family were studied clinically and with magnetic resonance imaging. Nine had strokelike episodes, including transient ischemic attacks, and minor or major strokes starting between the fourth and sixth decades, with neuroimaging evidence of small, deep infarcts and a widespread white matter disorder. Other symptoms included migraine (three), dementia (two), epilepsy (one), and hearing loss (one). In some patients, we found various immunologic anomalies and muscular lipidosis without ragged-red fibers. Eight other family members were clinically normal, but had identical neuroimaging signs of leukoencephalopathy. No abnormality was detected in the 28 other members of the family examined. Extensive investigations failed to reveal any known cause of cerebral ischemia.

CONCLUSIONS

There appears to be a new syndrome in this family that is characterized by recurrent subcortical strokelike episodes, leukoencephalopathy, immunologic anomalies, muscular lipidosis, and an autosomal dominant pattern of transmission.

Bax and Bcl-2 interaction in a transgenic mouse model of familial amyotrophic lateral sclerosis

It has been proposed that mutations in copper/zinc-superoxide dismutase (SOD1), the only proven cause of amyotrophic lateral sclerosis (ALS), induce the disease by a toxic property that promotes apoptosis. Consistent with this, we have demonstrated that overexpression of Bcl-2, a protein that inhibits apoptosis, attenuates neurodegeneration produced by the familial ALS-linked SOD1 mutant G93A (mSOD1). Herein, we assessed the status of key members of the Bcl-2 family in the spinal cord of transgenic mSOD1 mice at different stages of the disease. In asymptomatic transgenic mSOD1 mice, expression of Bcl-2, Bcl-XL, Bad, and Bax does not differ from that in nontransgenic mice. In contrast, in symptomatic mice, expression of Bcl-2 and Bcl-XL, which inhibit apoptosis, is reduced, whereas expression of Bad and Bax, which stimulate apoptosis, is increased. These alterations are specific to affected brain regions and are caused by the mutant and not by the normal SOD1 enzyme. Relevant to the neuroprotective effects of Bcl-2 in transgenic mSOD1 mice, overexpression of Bcl-2 increases the formation of Bcl-2:Bax heterodimers, which abolish the Bax proapoptotic property. This study demonstrates significant alterations in the expression of key members of the Bcl-2 family associated with mSOD1 deleterious effects. That these changes contribute to the neurodegenerative process in this model of ALS is supported by our observations in double transgenic mSOD1/Bcl-2 mice in which the pernicious increase of Bax is tempered by an increase in formation of Bcl-2:Bax heterodimers. Based on these findings, it may be concluded that Bcl-2 family members appear as invaluable targets for the development of new neuroprotective therapies in ALS.

Danon's disease as a cause of hypertrophic cardiomyopathy: a systematic survey

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disease caused by mutations in sarcomeric genes. However, extensive genetic screening failed to identify a mutation in about a third of cases. One possible explanation is that other diseases, caused by other genes, may mimic HCM.

OBJECTIVE

To investigate the possible involvement of Danon's disease, an X linked lysosomal disease, in a large population of patients with HCM.

METHODS

A population of 197 index cases was considered; 124 were subsequently excluded because of a mutation in sarcomeric genes and 23 because of autosomal dominant inheritance. Fifty index cases were therefore included in molecular analysis (direct sequencing) of the lysosome associated membrane protein 2 (LAMP2) gene responsible for Danon's disease.

RESULTS

Two new mutations leading to premature stop codons were identified in patients who evolved towards severe heart failure (< 25 years old): 657C>T and 173_179del. The prevalence was therefore 1% of the total population (two of 197) or 4% of enrolled index cases (two of 50). Interestingly, Danon's disease was responsible for half of the cases (two of four) with HCM and clinical skeletal myopathy but was not involved in isolated HCM (none of 41).

CONCLUSIONS

Danon's disease may be involved in patients with previously diagnosed as HCM. A diagnosis strategy is proposed. To distinguish HCM from Danon's disease is important because the clinical evolution, prognosis, mode of inheritance, and therefore genetic counselling are very different.

Diffusion of peroxynitrite in the presence of carbon dioxide

Peroxynitrite, the reactive species formed in vivo by the reaction of nitric oxide with superoxide anion, is capable of diffusing across erythrocyte membranes via anion channels and passive diffusion (A. Denicola, J. M. Souza, and R. Radi, Proc. Natl. Acad. Sci. USA 95, 3566-3571, 1998). However, peroxynitrite diffusion could be limited by extracellular targets, with the reaction with CO(2) (k(2) = 4.6 x 10(4) at 37 degrees C and pH 7.4) the most relevant. Herein, we studied the influence of physiological concentrations of CO(2) on peroxynitrite diffusion across intact red blood cells. The presence of CO(2) inhibited the oxidation of intracellular oxyhemoglobin by externally added peroxynitrite. However, the inhibition by CO(2) decreased at increasing red blood cell densities. At 45% hematocrit, 1.3 mM CO(2) (in equilibrium with 24 mM bicarbonate, at pH 7.4 and 25 degrees C) only inhibited 30% of intracellular oxyhemoglobin oxidation. This partial inhibition was also observed in red blood cells pretreated with the anion exchanger inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid, ruling out a competition between peroxynitrite and bicarbonate for the transport through the anion channel. A theoretical model was developed to estimate the diffusion distance and half-life of extracellular peroxynitrite before reacting with intracellular oxyhemoglobin, at different red blood cell densities, and in the presence or absence of CO(2). The theoretical model correlated well with the experimental data. Our results indicate that, even in the presence of CO(2), peroxynitrite is able to diffuse and reach the inside of the erythrocyte.

Vertical Flux of Biogenic Carbon in the Ocean: Is There Food Web Control?

Models of biogenic carbon (BC) flux assume that short herbivorous food chains lead to high export, whereas complex microbial or omnivorous food webs lead to recycling and low export, and that export of BC from the euphotic zone equals new production (NP). In the Gulf of St. Lawrence, particulate organic carbon fluxes were similar during the spring phytoplankton bloom, when herbivory dominated, and during nonbloom conditions, when microbial and omnivorous food webs dominated. In contrast, NP was 1.2 to 161 times greater during the bloom than after it. Thus, neither food web structure nor NP can predict the magnitude or patterns of BC export, particularly on time scales over which the ocean is in nonequilibrium conditions.

Mutational diversity and hot spots in the alpha-sarcoglycan gene in autosomal recessive muscular dystrophy (LGMD2D)

Sarcoglycanopathies are a genetically heterogeneous group of autosomal recessive muscular dystrophies in which the primary defect may reside in any of the genes coding for the different partners of the sarcolemmal sarcoglycan (SG) complex: the alpha-SG (LGMD2D at 17q21.2), the beta-SG (LGMD2E at 4q12), the gamma-SG (LGMD2C at 13q12), and the delta-SG (LGMD2F at 5q33). We report a series of 20 new unrelated families with 14 different mutations in the alpha-SG gene. Along with the mutations that we previously reported this brings our cohort of patients with alpha-sarcoglycanopathy to a total of 31 unrelated patients, carrying 25 different mutations. The missense mutations reside in the extracellular domain of the protein. Five of 15 missense mutations, carried by unrelated subjects on different haplotype backgrounds and of widespread geographical origins, account for 58% of the mutated chromosomes, with a striking prevalence of the R77C substitution (32%). The severity of the disease varies strikingly and correlates at least in part with the amount of residual protein and the type of mutation. The recurrent R284C substitution is associated with a benign disease course.

Different mechanisms inferred from sequences of human mitochondrial DNA deletions in ocular myopathies

We have sequenced the deletion borders of the muscle mitochondrial DNA from 24 patients with heteroplasmic deletions. The length of these deletions varies from 2.310 bp to 8.476 bp and spans from position 5.786 to 15.925 of the human mitochondrial genome preserving the heavy chain and light chain origins of replication. 12 cases are common deletions identical to the mutation already described by other workers and characterized by 13 bp repeats at the deletion boundaries, one of these repeats being retained during the deletion process. The other cases (10 out of 12) have shown deletions which have not been previously described. All these deletions are located in the H strand DNA region which is potentially single stranded during mitochondrial DNA replication. In two cases, the retained Adenosine from repeat closed to the heavy strand origin of replication would indicate slippage mispairing. Furthermore in one patient two mt DNA molecules have been cloned and their sequences showed the difference of four nucleotides in the breakpoint of the deletion, possibly dued to slippage mispairing. Taken together our results suggest that deletions occur either by slippage mispairing or by internal recombination at the direct repeat level. They also suggest that different mechanisms account for the deletions since similarly located deletions may display different motives at the boundaries including the absence of any direct repeat.

Physiological and morphological responses of green microalgae Chlorella vulgaris to silver nanoparticles

The toxic effects of silver nanoparticles (AgNPs) on the physiology and morphology of the green microalga Chlorella vulgaris were studied. AgNPs were characterized by particle size distribution, ζ potential measurement, and atomic force microscopy (AFM). Chlorella vulgaris was exposed to 90-1440 μg/L of AgNPs range in Bold's Basal Medium for 96 h. The inhibition of algae growth rate and changes in the concentrations of chlorophyll-a, chlorophyll-b, pheophytin, and carotenoids was determined at the beginning and end of the trial. Cell diameter and volume, carbohydrate, total lipids, and protein content were also determined. Our data strongly suggest that the toxic effects of the AgNPs resulted in concentration and time-dependent. AgNPs altered C. vulgaris growth kinetics and cell metabolism expressed in photosynthetic pigments and biochemical composition. Our study confirmed the cytotoxicity of AgNPs through the algal growth inhibition with an EC₅₀ value of 110 μg/L. Also, changes of chlorophyll-a, chlorophyll-b, pheophytin, and carotenoids concentrations were observed associated with a color shift from green to pale brown of algae cultures exposed to AgNPs for 96 h. Furthermore, algae cell concentration, diameter, and volume, plus total lipid, protein, and carbohydrates contents in the presence of AgNPs, were significantly altered compared to untreated cells. In synthesis, this study highlighted AgNPs toxic effects on morphological and physiological traits of C. vulgaris and warns about possible impacts on energy flow and aquatic food web structure, and on the transfer efficiency of energy to higher trophic levels.

Mapping of heteroplasmic mitochondrial DNA deletions in Kearns-Sayre syndrome

Kearns-Sayre syndrome (KSS) is a progressive neuromuscular disease characterised by ophtalmoplegia, cardiac bloc branch, pigmentary retinopathy associated with abnormal mitochondrial function. We have studied the mitochondrial DNA organization of patients presenting KSS and have found large deletions ranging from 3 to 8.5 kilobase pairs. DNA molecules containing deletion are accompanied by the presence of the normal sized mtDNA molecule forming heteroplasmic genomes. The deletions always map in the region which is potentially single stranded during mitochondrial DNA replication. The deletions differ in length and position between individuals but are similar within the different tissues of an individual suggesting that they arise during or before embryogenesis.

Genetic biochemical and pathophysiological characterization of a familial mitochondrial encephalomyopathy (MERRF)

Myoclonic epilepsy with ragged-red fibers (MERRF) syndrome is a neuromuscular disorder characterized by mitochondrial myopathy and progressive myoclonus epilepsy. A heteroplasmic A to G transition mutation in the mitochondrial encoded tRNA(Lys) gene at nucleotide pair 8344 has been suggested to be linked to the MERRF-syndrome. We have investigated biochemically and histochemically muscle biopsies and studied the mitochondrial genomes of hair, blood and muscle tissue of a family including three cases of MERRF-syndrome as well as unaffected relatives within the maternal lineage. Sequence analysis of the mtDNAs, performed after amplification by the polymerase chain reaction (PCR), confirmed the A to G transition mutation in the tRNA(Lys) gene at position 8344. The additional point mutation at nucleotide pair 750 in the 12 S rRNA gene, which was also found by Shoffner et al. (1990), however, was absent in all investigated tissues. Quantitative analysis of the percentage of mutated mtDNA by mispairing PCR (Seibel et al., 1990) revealed variable contents in different tissues and individuals, including unaffected family members. Mitochondrial protein synthesis in cultured fibroblasts from MERRF patients revealed diminished incorporation of 35S-methionine into lysine-containing peptides.

Brain-derived neurotrophic factor inhibits apoptosis and dopamine-induced free radical production in striatal neurons but does not prevent cell death

In hereditary Huntington's disease, a triplet repeat disease, there is extensive loss of striatal neurons. It has been shown that brain-derived neurotrophic factor (BDNF) protects striatal neurons against a variety of insults. We confirmed that BDNF enhances survival and DARPP-32 expression in primary striatal cultures derived from postnatal mice. Furthermore, BDNF inhibited intracellular oxyradical stress triggered by dopamine, and partially blocked basal and dopamine-induced apoptosis. Nevertheless, BDNF failed to rescue striatal neurons from dopamine-induced cell death. Therefore, BDNF inhibits free radical and apoptotic pathways in medium spiny neurons, but does so downstream from the point of commitment to cell death.

Localization of the Schwartz-Jampel syndrome (SJS) locus to chromosome 1p34-p36.1 by homozygosity mapping

Schwartz-Jampel syndrome (SJS, MIM 255800), also known as chondrodystrophic myotonia, is a rare autosomal recessive disorder characterized by generalized myotonia, skeletal abnormalities and facial dysmorphism. Using homozygosity mapping, we localized the SJS locus to chromosome 1p34-p36.1 in a 8 cM interval flanked by markers D1S199 and D1S234. Families of different ethnic backgrounds (Tunisia and South Africa) showed genetic linkage to the same locus. Moreover, one Algerian family also demonstrated evidence of genetic linkage to 1p34-p36.1. Taken altogether, our results suggest genetic homogeneity, at least in the group of families analyzed.

Identification of point mutations by mispairing PCR as exemplified in MERRF disease

The point mutation in the tRNA(Lys) gene of mitochondrial DNA (mtDNA) from patients with myoclonic epilepsy and ragged red fibers (MERRF) was quantitatively analyzed after digestion with the restriction endonuclease Nae I of the PCR amplified DNA. Since the point mutation is not part of a restriction site for a commonly available restriction endonuclease, the Nae I restriction site was introduced by PCR using a mispairing primer. The percentage of mutated mtDNA was determined in a few hairs of five members of an affected family by counting the radioactivity of the fragments after PCR amplification with labelled dATP.

Role of copper in the regulation and accumulation of superoxide dismutase and metallothionein in rat liver

Weanling male Sprague-Dawley rats were fed one of four diets that varied in Cu, Zn or Cd content. To the control diet (I) Cu, Zn and Cd were added at 10, 100 and 0 mg/kg diet, respectively. Diets II and III also contained 10 mg/kg of dietary Cu, except that Zn was elevated to 1000 mg/kg for diet II, or Cd was added at 10 mg/kg for diet III. Diet IV was deficient in Cu (less than 1 mg/kg) with Zn at 100 mg/kg and no added Cd. At wk 6 postweaning, half of the rats fed diets I and IV were injected once with Cd acetate (5 mg Cd/kg body weight). The immediate response to Cd injection was an increase in metallothionein accumulation (three- to fourfold) and in Cu,Zn superoxide dismutase (SOD) accumulation (1.2- to 1.5-fold) in liver. SOD was estimated in an ELISA. These responses were not influenced by a change in Cu status (I vs. IV). However, in functional assays, SOD enzymatic activity was about half that of the control values. In this regard, SOD appears to be given high priority with respect to the utilization of cellular Cu, i.e., a 10-fold reduction in hepatic Cu only resulted in a twofold reduction in SOD activity and the amount of apoenzyme remained at normal levels.

Mice transgenic for exon 1 of the Huntington's disease gene display reduced striatal sensitivity to neurotoxicity induced by dopamine and 6-hydroxydopamine

Huntington's disease is an autosomal dominant hereditary neurodegenerative disorder characterized by severe striatal cell loss. Dopamine (DA) has been suggested to play a role in the pathogenesis of the disease. We have previously reported that transgenic mice expressing exon 1 of the human Huntington gene (R6 lines) are resistant to quinolinic acid-induced striatal toxicity. In this study we show that with increasing age, R6/1 and R6/2 mice develop partial resistance to DA- and 6-hydroxydopamine-mediated toxicity in the striatum. Using electron microscopy, we found that the resistance is localized to the cell bodies and not to the neuropil. The reduction of dopamine and cAMP regulated phosphoprotein of a molecular weight of 32 kDa (DARPP-32) in R6/2 mice does not provide the resistance, as DA-induced striatal lesions are not reduced in size in DARPP-32 knockout mice. Neither DA receptor antagonists nor a N-methyl-d-aspartate (NMDA) receptor blocker reduce the size of DA-induced striatal lesions, suggesting that DA toxicity is not dependent upon DA- or NMDA receptor-mediated pathways. Moreover, superoxide dismutase-1 overexpression, monoamine oxidase inhibition and the treatment with the free radical scavenging spin-trap agent phenyl-butyl-tert-nitrone (PBN) also did not block DA toxicity. Levels of the antioxidant molecules, glutathione and ascorbate were not increased in R6/1 mice. Because damage to striatal neurons following intrastriatal injection of 6-hydroxydopamine was also reduced in R6 mice, a yet-to-be identified antioxidant mechanism may provide neuroprotection in these animals. We conclude that striatal neurons of R6 mice develop resistance to DA-induced toxicity with age.

Gallium-67 scintigraphy in macrophagic myofasciitis

OBJECTIVE

To evaluate gallium-67 (67Ga) uptake and the value of 67Ga scintigraphy for diagnosis of macrophagic myofasciitis (MMF), a recently identified inflammatory myopathy.

METHODS

Twelve consecutive patients with MMF confirmed by muscle biopsy, 10 with polymyositis, 10 with sarcoidosis, 8 with fibromyalgia, and 10 with lymphoma without muscle symptoms (serving as normal controls for muscle) were included. Patients received 1.8 MBq 67Ga per kg body weight by intravenous injection, and scintigraphy was performed with a 2-head gamma camera. The various views were acquired for the 3 main photopeaks of 67Ga 48 hours after infusion, and were analyzed in 2 blinded experiments by nuclear physicians. A semiquantitative scale was used to compare the uptake of 67Ga in the vascular soft tissue background with that in the muscles or joints of MMF patients, and with that in the normal controls.

RESULTS

The MMF patients (4 men and 8 women, mean +/- SD age 47.8 +/- 8.7 years) had chronic myalgia (n = 11; predominantly in the lower limbs), asthenia (n = 10), arthralgia (n = 7), mild muscle weakness (n = 5), and high serum creatine kinase levels (n = 6). All MMF patients had significantly higher levels of 67Ga uptake in the muscle and para-articular areas than that recorded for the soft tissue background and for the controls. Muscle uptake was bilateral, symmetric, and homogeneous, and predominantly localized in the legs. No linear enhancement corresponding to fascias or synovial involvement was observed. In patients with polymyositis, symmetric, but heterogeneous, 67Ga uptake was observed in muscle, but not in the fascia. In patients with sarcoidosis, 67Ga uptake was nodular and heterogeneous in muscle, was not detected in the fascia, and was suggestive of synovial involvement in the joints. The uptake of 67Ga in fibromyalgic patients was similar to that in normal controls and to that in the soft tissue background.

CONCLUSION

MMF is a new condition involving characteristic changes that can be detected by deltoid muscle biopsy. It usually manifests as a weakly specific, chronic arthromyalgic syndrome that predominates in the lower limbs. 67Ga scintigraphy is a noninvasive method that may make it easier to differentiate MMF from fibromyalgia and sarcoidosis.

Deletions of mitochondrial DNA in Kearns-Sayre syndrome and ocular myopathies: genetic, biochemical and morphological studies

Genetic, biochemical and morphological investigations were conducted on skeletal muscle mitochondria from 6 cases of ocular myopathy: 4 cases with Kearns-Sayre syndrome (KSS) and 2 with chronic progressive external ophthalmoplegia. All of these 6 cases showed mitochondrial DNA (mtDNA) deletions in addition to normal sized DNA in the quadriceps muscle. The deletions ranging from 3 to 8 kbp were also mapped between nucleotides 5500 and 16000 by Southern blot. The deleted genes encoded for some subunits of complexes I, IV, V and 5-10 tRNAS. The boundaries of the deletions have been sequenced in three patients. Five patients had mitochondrial respiratory chain deficiency in complex I as shown by the low oxygen consumption in isolated mitochondria using three NAD(+)-linked substrates. Mitochondria with an abnormal ultrastructure were also observed in 2 cases. A good relationship between the cytochrome c oxidase deficiency and the amount of deleted mtDNA was shown in our present investigations.