Abnormalities in the expression of beta-spectrin in Duchenne muscular dystrophy

We studied beta-spectrin using an immunologic probe in muscle samples from patients with Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), other disease controls, and normal controls. By immunohistochemistry in DMD samples, beta-spectrin showed reduced or interrupted staining of the entire cell surface or only patches of bright staining at the cell periphery. There were also alterations of beta-spectrin immunostain in fibers that were not degenerating or regenerating. By immunoblotting, the amount of beta-spectrin in muscle was reduced and varied from 52% to 78% of the normal controls. We found normal values of beta-spectrin in BMD and disease controls. These observations indicate that the expression of beta-spectrin in DMD is abnormal and that beta-spectrin immunolabeling is not a good marker for monitoring membrane integrity in DMD muscle.

Manganese toxicity: muscarinic receptor binding in the mouse brain

In the present study we determined the effect of repeated administration of manganese chloride on the binding parameters of [3H]quinuclidinyl benzilate (3H-QNB) in striatum, frontal cortex, and hippocampus of mice. Daily intraperitoneal injections of manganese chloride (5 mg Mn/kg) 5 d/wk during 9 wk did not alter the receptor density (Bmax) and the dissociation constant (Kd) of 3H-QNB in the different brain regions studied. These results suggest that chronic treatment with manganese does not affect the binding characteristics of 3H-QNB to the cholinergic muscarinic receptors in mouse brain.

Mitochondrial DNA deletion: a cause of chronic tubulointerstitial nephropathy

We report the first case of a mitochondrial DNA (mtDNA) deletion diagnosed by renal biopsy. An eight-year-old girl with megaloblastic anemia and severe growth retardation developed progressive renal insufficiency accompanied by partial Fanconi syndrome. Histologic examination of the renal biopsy disclosed nonspecific chronic tubulointerstitial disease characterized by tubular atrophy and interstitial fibrosis. On ultrastructural examination, tubular cell mitochondria were extremely dysmorphic with prominent size variation, abnormal arborization, disorientation of the cristae and osmiophilic electron-dense inclusions. Functional histochemical stains for mitochondrial enzymes performed on cryostat renal sections revealed focal tubular absence of cytochrome C oxidase (COX), a respiratory chain enzyme partially encoded by mtDNA, with preservation of succinate dehydrogenase (SDH), a respiratory chain enzyme entirely encoded by nuclear DNA (nDNA). Immunoreactivity for COX subunit 2 (encoded by mtDNA) was weak to undetectable in most tubular cells, whereas reactivity for subunit 4 (encoded by nDNA) was intense in all cells. Molecular analysis of the mtDNA of kidney and peripheral blood leukocytes was performed using Southern blot and PCR. Both techniques disclosed a 2.7 kb mtDNA deletion located between nucleotide (nt) 9700 and nt 13700, a common site for mtDNA deletions associated with encephalomyopathies. Mitochondrial DNA deletions may be an under-recognized cause of idiopathic tubulointerstitial nephropathy in children lacking neurologic or myopathic manifestations.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE): clinical, biochemical, and genetic features of an autosomal recessive mitochondrial disorder

We studied the clinical, biochemical, and genetic features of eight patients with the autosomal recessive mitochondrial syndrome mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). MNGIE is clinically characterized by ophthalmoparesis, peripheral neuropathy, leukoencephalopathy, gastrointestinal symptoms (recurrent nausea, vomiting, or diarrhea) with intestinal dysmotility, and histologically abnormal mitochondria in muscle. Brain MRI scans were consistent with leukodystrophy in seven patients examined. Nerve conduction and EMG studies were compatible with a sensorimotor neuropathy; quantitative EMG of two patients suggested a myogenic process. Muscle mitochondrial enzyme analysis revealed a partial defect of cytochrome c oxidase activity in five patients; three had additional respiratory chain enzyme defects. Two patients had isolated complex I defects, and one had normal respiratory chain function. Southern blot analysis revealed multiple deletions of mitochondrial DNA in four of eight patients.

Extremely high levels of mutant mtDNAs co-localize with cytochrome c oxidase-negative ragged-red fibers in patients harboring a point mutation at nt 3243

A single mtDNA point mutation at nt 3243 has been associated with two different clinical phenotypes: mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes ('MELAS3243') and progressive external ophthalmoplegia ('PEO3243'). It has been shown that there is a much higher proportion of ragged-red fibers (RRF) with cytochrome c oxidase (COX) deficiency in PEO3243 than in MELAS3243. Using PCR/RFLP analysis of isolated individual skeletal muscle fibers from patients with both syndromes, we found a direct correlation between the localized concentration of the nt 3243 mutation and impairment of COX function at the single muscle fiber level: we found relatively low levels of mutant mtDNAs (56 +/- 21%) in 'normal' fibers; high levels (90 +/- 6%) in COX-positive RRF; and an almost complete segregation of mutant mtDNAs (95 +/- 3%) in COX-negative RRF. Thus, the differential distribution of fibers with extremely high concentrations of mutant mtDNAs characterizes, and probably distinguishes, the skeletal muscle of PEO and MELAS patients harboring the same nt-3243 mutation.

Distribution of wild-type and common deletion forms of mtDNA in normal and respiration-deficient muscle fibers from patients with mitochondrial myopathy

We studied the cellular distribution of both deleted (delta) and wild-type (wt) mitochondrial DNAs (mtDNAs) in 'normal' and respiration-deficient muscle fibers from four patients with mitochondrial myopathy. PCR-based methods were used to quantitate both relative and absolute amounts of delta- and wt-mtDNAs in microdissected fiber segments. Although delta-mtDNAs were present in normal fibers (31% +/- 26), their percentages were much higher in affected fibers (95% +/- 2). Absolute levels of delta-mtDNA were also increased in affected fibers, whereas levels of wt-mtDNA were significantly reduced in these fibers. These results indicate that a threshold ratio of delta-/wt-mtDNA must be achieved before an impairment of respiration is observed in muscle. Moreover, the marked reduction in wt-mtDNA observed in affected fibers suggests that absolute amounts of mtDNA may play a role in the pathogenesis of mitochondrial myopathies.

Gender-related differences in the impact of tropical diseases on women: what do we know?

This paper explores the importance of gender differences in the impact of tropical diseases on women. Malaria and schistosomiasis are used as examples but most of the observations also apply to other diseases endemic to developing countries. The distinction between sex and gender is discussed and evidence of sex and gender differences in the determinants and consequences of malaria and schistosomiasis, particularly their economic, social and personal dimensions, is reviewed. Issues on which research and intervention studies are needed are identified.

Two novel pathogenic mitochondrial DNA mutations affecting organelle number and protein synthesis. Is the tRNA(Leu(UUR)) gene an etiologic hot spot?

We identified two patients with pathogenic single nucleotide changes in two different mitochondrial tRNA genes: the first mutation in the tRNA(Asn) gene, and the ninth known mutation in the tRNA(Leu(UUR)) gene. The mutation in tRNA(Asn) was associated with isolated ophthalmoplegia, whereas the mutation in tRNA(Leu(UUR)) caused a neurological syndrome resembling MERRF (myoclonus epilepsy and ragged-red fibers) plus optic neuropathy, retinopathy, and diabetes. Both mutations were heteroplasmic, with higher percentages of mutant mtDNA in affected tissues, and undetectable levels in maternal relatives. Analysis of single muscle fibers indicated that morphological and biochemical alterations appeared only when the proportions of mutant mtDNA exceeded 90% of the total cellular mtDNA pool. The high incidence of mutations in the tRNA(Leu(UUR)) gene suggests that this region is an "etiologic hot spot" in mitochondrial disease.

Determining malaria effects in rural Colombia

Good health is an integral component of the quality of human life, a prerequisite for developing human potential and an important determinant of economic development. When a person is ill from a tropical disease in an agricultural economy, a complex interaction between the individual's welfare and the family's welfare is set in motion. So complex are these interactions that few empirical studies exist on this subject and even where they do, empirical quantification of these interactions and economic losses places the analyst in the minefield of valuing time, ability and contribution to economic welfare. Placing monetary values on these commodities is always a little unsatisfactory since dollar values do not adequately reflect the nature of the losses. Secondly, the ill person's struggle to minimize the economic effects of disease on family income will mask its true impact; thirdly, tropical diseases disproportionately affect low-income groups and therefore measuring the income effects of disease amongst these groups will only reach at the earnings effect, and underestimate the economic implications of tropical disease control. Despite these difficulties, quantification of the economic impact of disease is important from a public health point of view. This study is an attempt at such a task, and focuses on the intra-familial struggle to minimize economic losses due to malaria. Using a case-control approach, time-losses and labour reallocations within the household are examined in an attempt to understand the economic consequences of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Dystrophinopathy in two young boys with exercise-induced cramps and myoglobinuria

Two young boys were referred for evaluation of metabolic myopathy because of elevated serum levels of creatine kinase, cramps and pigmenturia. Immunohistochemical studies of dystrophin in muscle biopsies showed reduced intensity of the stain with a patchy and discontinuous pattern in most fibers. In both patients dystrophin was undetectable by immunoblotting. DNA analysis of the dystrophin gene was not informative in one patient; in the other it revealed an in-frame deletion comprising exons 3-6. These observations suggest that the two patients are affected with an unusual phenotype of Becker muscular dystrophy. Dystrophin analysis should be included in the evaluation of patients with childhood-onset of recurrent myoglobinuria.

Cytochrome C oxidase deficiency and neuronal involvement in Menkes' kinky hair disease: immunohistochemical study

Antibodies against subunits II and IV of cytochrome c oxidase (COX) and against complex III of the respiratory chain were used to study the expression of these proteins in the cerebellum, spinal cord, and other regions of the central nervous system in an autoptic case of Menkes' kinky hair disease (MKHD). We found a reduced expression of COX subunits in all examined areas whereas staining for complex III appeared normal. Immunostaining was altered in morphologically well-preserved neurons, suggesting that COX deficiency may have a pathogenetic role in the neuronal degeneration of MKHD.

A mitochondrial tRNA anticodon swap associated with a muscle disease

We have identified an unusual mitochondrial (mt) tRNA mutation in a seven year-old girl with a pure myopathy. This G to A transition at mtDNA position 15990 changed the anticodon normally found in proline tRNAs (UGG) to the one found in serine tRNAs (UGA), and is the first pathogenic anticodon alteration described in a higher eukaryote. The mutant mtDNA was heteroplasmic (85% mutant) in muscle but was undetectable in white blood cells from the patient and her mother. Analysis of single muscle fibres indicated that mutant mtDNAs severely impaired mitochondrial protein synthesis and respiratory chain activity, but only when present at greater than 90%. The recessive behaviour of this mtDNA alteration may explain the patient's relatively mild clinical phenotype.

Cryptosporidium infections in a suburban community in Maracaibo, Venezuela

A point prevalence survey for Cryptosporidium was conducted in 212 subjects two months to 70 years of age in a suburban area with a low socioeconomic status in Maracaibo City, Venezuela. Single stool specimens were collected and modified Ziehl-Neelsen carbol-fuchsin staining of 10% formalin-preserved stool was used to identify Cryptosporidium oocysts. Direct wet mounts, iron-hematoxylin-stained smears and formalin-ether concentrates were examined to determine the presence of other intestinal parasites. Cryptosporidium infections were identified in 21 subjects (9.9%), with a high percentage of asymptomatic carriers (15 of 21, 71.4%). Six children (28.5%) had gastrointestinal symptoms and four of them were infants. Cryptosporidium was the single detectable potential pathogenic parasite in only five (23.8%) of 21 patients. The infection rate with one or more parasites was high (82%) and multiple infections, including pathogenic helminths and protozoa, were observed in the majority of patients who passed oocysts. Our findings suggest that although Cryptosporidium is an important pathogen, the proportion of asymptomatic carriers may be high in areas of low socioeconomic status in developing countries.

Atypical clinical presentations associated with the MELAS mutation at position 3243 of human mitochondrial DNA

Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is commonly associated with an A-->G transition at position 3243 of the mitochondrial DNA. To determine the diversity of clinical syndromes associated with this mutation, 91 patients with mitochondrial encephalomyopathies that did not conform to the MELAS phenotype were screened. Twenty one patients with the 3243 mutation, most of whom had progressive external ophthalmoplegia (PEO) were found. Clinical features did not distinguish PEO patients with the 3243 mutation from those with large-scale deletions of mtDNA. However, most cases with single large-scale mtDNA deletions were sporadic, whereas most patients with the 3243 mutation had affected maternal relatives. Histochemical studies of muscle showed that cytochrome c oxidase (COX) deficiency was more severe in patients with PEO than in patients with typical MELAS, even though PEO patients had a lower percentage of mutant genomes in muscle. These data imply that the 3243 mutation is a major cause of familial PEO, and suggests that the threshold number of mtDNAs harboring the 3243 mutation necessary to affect a particular tissue vary in different patients. The proportion of mutant genomes in combination with other, still undefined, tissue-specific modulating factors seem to determine the overall clinical syndrome.

Immunolocalization of heat shock proteins in ragged-red fibers of patients with mitochondrial encephalomyopathies

Monoclonal antibodies against the 60 kDa heat shock protein (HSP-60) and against ubiquitin (UB) were used to study the expression of these proteins in muscle samples from patients with qualitative and quantitative alterations of mitochondrial DNA (mtDNA). We found an enhanced expression of HSP-60 and UB that was preferentially localized in ragged-red fibers (RRFs). HSP-60 may act as a protein repair enzyme catalyzing the refolding of misfolded proteins in the matrix of mitochondria of RRFs. On the other hand, UB could promote the elimination of abnormal proteins by its covalent interaction to substrates.

Carrier detection of Duchenne and Becker muscular dystrophy using muscle dystrophin immunohistochemistry

To ascertain whether dystrophin immunohistochemistry could improve DMD/BMD carrier detection, we analyzed 14 muscle biopsies from 13 DMD and one BMD probable and possible carriers. All women were also evaluated using conventional methods, including genetic analysis, clinical and neurological evaluation, serum CK levels, EMG, and muscle biopsy. In 6 cases, there was a mosaic of dystrophin-positive and dystrophin-deficient fibers that allowed to make the diagnosis of a carrier state. Comparing dystrophin immunohistochemistry to the traditional methods, it was noted that this method is less sensitive than serum CK measurements, but is more sensitive than EMG and muscle biopsy. The use of dystrophin immunohistochemistry in addition to CK, EMG and muscle biopsy. improved the accuracy of carrier detection. This method is also helpful to distinguish manifesting DMD carriers from patients with other neuromuscular diseases like limb-girdle muscular dystrophy and spinal muscular atrophy.

Acute quadriplegic myopathy: a complication of treatment with steroids, nondepolarizing blocking agents, or both

We studied two patients who were given high-dose intravenous steroid therapy and were intubated for status asthmaticus. Both became quadriplegic and wasted within 2 weeks. EMG had myopathic abnormalities. Muscle biopsy revealed severe atrophy of most muscle fibers, with disorganization of myofibrils and selective loss of thick (myosin) filaments. Immunohistologic stains for myosin isoforms confirmed the decrease or absence of this protein. Both patients clinically improved over several months.

Immunologic study of vinculin in Duchenne muscular dystrophy

Using immunologic techniques, we studied vinculin, a cytoskeletal protein associated with the membrane-skeleton of the muscle fiber. We examined muscle biopsies from five patients with Duchenne muscular dystrophy (DMD), two with Becker's muscular dystrophy (BMD), three normal human muscle samples, and four biopsies from disease control patients. All DMD patients showed patchy and low-intensity immunostain at the sarcolemma of most fibers and, by immunoblot analysis, the content of vinculin was 42 to 61% of control values. There was no significant vinculin deficiency in samples from patients with BMD and other disease controls. The data suggest that vinculin content is reduced only in muscle where dystrophin is absent or sparse.

Molecular analysis of the muscle pathology associated with mitochondrial DNA deletions

Large-scale deletions of mitochondrial DNA (mtDNA) are associated with a subgroup of mitochondrial encephalomyopathies. We studied seven patients with Kearns-Sayre syndrome or isolated ocular myopathy who harboured a sub-population of partially-deleted mitochondrial genomes in skeletal muscle. Variable cytochrome c oxidase (COX) deficiencies and reduction of mitochondrially-encoded polypeptides were found in affected muscle fibres, but while many COX-deficient fibres had increased levels of mutant mtDNA, they almost invariably had reduced levels of normal mtDNA. Our results suggest that a specific ratio between mutant and wild-type mitochondrial genomes is the most important determinant of a focal respiratory chain deficiency, even though absolute copy numbers may vary widely.

Prevalence of Entamoeba histolytica and other intestinal parasites in a community from Maracaibo, Venezuela

The prevalences of Entamoeba histolytica and other intestinal parasites were assessed in a suburban community of Maracaibo, Venezuela, by examination of a stool specimen from each of 342 individuals, using iron-haematoxylin stained faecal smears and formalin-ether concentration. The overall parasitic infection rate was 80.4%, and 65.8% of the population had multiple infections. The overall amoebic infection rate, which was highest in female adults, averaged 39.7%. The E. histolytica infection rate was 8.7% and most of those infected were passing cysts. Entamoeba polecki was observed in two samples. Amongst the protozoa, Entamoeba coli was observed most frequently (24.8%) and Giardia lamblia was the predominant pathogen (13.0%). Trichuris trichiura (71.9%) and Ascaris lumbricoides (54%) were the most common parasites, particularly in school-children. The high rates of parasitic and multiple infections reflect the low socio-economic status of the community studied.

Transanorectal approach for the treatment of urogenital sinus: preliminary report

The treatment of the urogenital sinus with normal rectum still represents a challenge. A perineal approach with or without a skin flap seems to be effective for those patients with a low implantation of the vagina. However, in patients with a high vaginal implantation, this treatment frequently fails to provide a good, functional vagina due to a narrow, strictured vaginal opening. Based on previous experience in the treatment of more than 80 patients with a persistent cloaca, a posterior sagittal transanorectal approach with a protective colostomy was performed in three patients with urogenital sinus and normal rectum. The pelvis was approached through a midsagittal posterior incision; the coccyx was split and the entire anorectal sphincteric mechanism was divided in the midline. The rectum was bivalved in the midline including both posterior and anterior rectal walls. This provided excellent exposure to the urogenital sinus. The vagina was then fully separated from the urogenital sinus (as described in cases of persistent cloacas), and then mobilized and sutured to the perineum. The rectum and sphincteric mechanism were meticulously reconstructed. A midline incision assures the preservation of anorectal innervation, and provides excellent exposure to the pelvis. Anal dilatations are not necessary to maintain a patent and supple anorectal opening because the rectum has two suture lines, one in front of the other. After the colostomy was closed, all patients had appropriate bowel control for their age; two of them are fully continent for urine and the third one still has a suprapubic cystostomy tube waiting for a repair of an additional urethral malformation.

Dystrophinopathy in isolated cases of myopathy in females

X-linked dystrophinopathy is the most common cause of isolated cases of myopathy in males. To investigate dystrophin abnormalities as a cause of myopathy in girls and women, we used dystrophin immunocytochemistry to study muscle biopsies from 505 girls and women with neuromuscular disease. Forty-six muscle biopsies showed a combination of fibers containing or lacking dystrophin; this mosaic immunostaining pattern denoted a carrier status. Twenty-one of 46 (45.6%) had a family history of Duchenne muscular dystrophy in males. Twenty-five of 46 (54.3%) were isolated cases, with no previous family history of neuromuscular disorder. The laboratory findings of the isolated cases were consistent with the familial cases; all showed myopathic histopathology and abnormal elevations of serum CK. The clinical presentations of the isolated cases varied but were consistent with the familial cases: 40% (10/25) of isolated cases showed proximal limb weakness before age 10, 24% (6/25) presented with myalgias or cramps, 24% (6/25) presented with incidental findings of grossly elevated CK levels, 8% (2/25) noted easy fatigue, and 4% (1/25) had slowly progressive proximal limb weakness beginning at age 45. From our data, the clinical criteria for consideration of an underlying dystrophinopathy in isolated female cases of myopathy are CK levels greater than 1,000 IU/l and myopathic histopathology. About 10% of the isolated cases of hyperCKemic myopathy (25/210) were proven by dystrophin analysis to have a dystrophinopathy as the cause of their disease (manifesting carriers of Duchenne dystrophy). However, we feel that this may be an underestimate. The correct diagnosis in these patients is imperative for appropriate genetic counseling to the patients and their families.