Autosomal recessive Bethlem myopathy.

BACKGROUND: Bethlem myopathy is a well-defined clinical entity among collagen VI disorders, featuring proximal muscle weakness and contractures of the fingers, wrists, and ankles. It is an early-onset, slowly progressive, and relatively mild disease, invariably associated to date with heterozygous dominant mutations in the 3 collagen VI genes. We have characterized the clinical, laboratory, and genetic features of autosomal recessive Bethlem myopathy in 2 unrelated patients. METHODS: This study is based on clinical, histochemical, immunocytochemical, and electron microscope evaluation of the muscle and dermal fibroblasts, CT imaging of the muscles, and biochemical and molecular analysis. RESULTS: Both patients carry a truncating COL6A2 mutation (Q819X; R366X) associated with missense changes in the partnering allele lying within the C2 domain of the alpha2(VI) chain (D871N; R843W-R830Q). They show decreased amounts of collagen VI in the basal lamina of muscle fibers and in dermal fibroblast cultures and altered behavior of collagen VI tetramers. Biochemical studies supported the pathogenic effect of identified amino acid substitutions, which involve strictly conserved residues. CONCLUSIONS: The reported patients illustrate the occurrence of Bethlem myopathy with a recessive mode of inheritance. This observation completes the hereditary pattern in collagen VI myopathies with both Ullrich congenital muscular dystrophy and Bethlem myopathy underlined by either recessive or dominant effecting mutations. This finding has relevant implications for genetic counseling and molecular characterization of patients with Bethlem myopathy, as well as for genotype-phenotype correlations in collagen VI disorders.

Transcriptional behavior of DMD gene duplications in DMD/BMD males.

DMD gene exons duplications account for up to 5-10 % of Duchenne (DMD) and up to 5-19% of Becker (BMD) muscular dystrophies; as for the more common deletions, the genotype-phenotype correlation and the genetic prognosis are generally based on the "reading frame rule". Nevertheless, the transcriptional profile of duplications, abridging the genomic configuration to the eventual protein effect, has been poorly studied. We describe 26 DMD gene duplications occurring in 33 unrelated patients and detected among a cohort of 194 mutation-positive DMD/BMD patients. We have characterized at the RNA level 16 of them. Four duplications (15%) behave as exception to the reading frame rule. In three BMD cases with out-of-frame mutations, the RNA analysis revealed that exon skipping events occurring in the duplicated region represent the mechanism leading to the frame re-establishment and to the milder phenotype. Differently, in a DMD patient carrying an in-frame duplication the RNA behaviour failed to explain the clinical phenotype which is probably related to post-transcriptional-translational mechanisms. We conclude that defining the RNA profile in DMD gene duplications is mandatory both for establishing the genetic prognosis and for approaching therapeutic trials based on hnRNA modulation.

The evolution of the atheromatous plaque: ultrastructural evidence.

Our understanding of endothelial physiology is overdue compared with other areas of study. For too many years the complex mysteries of this thin single-layered cellular lamina covering the whole of the vascular network, from the large conduction vessel to the smallest resistance and diffusion vessel, have been hidden by an organ-based science more focused on organ pathology than on ultrastructural physiopathology. We tried to follow chronologically the alteration stages of this system of membranes in relation to the development of the atherosclerotic plaque in human biopsy.

One case of immunotactoid glomerulopathy: morphological-ultrastructural aspects.

Starting from a group of 736 renal biopsy patients, evaluated by ultrastructural studies over a period of 22 years, the authors present a rare case of immunotactoid glomerulopathy, suggesting that these forms, until a few years ago considered in the same group as fibrillary glomerulonephritis, are in fact a separate entity; moreover, they may represent a very early manifestation of plasmacellular dyscrasia still at the initial stage.

Birbeck granules: contribution to the comprehension of intracytoplasmic evolution.

We investigated the ultrastructure of Birbeck granules which are found in some malignant histiocytoses such as histiocytosis X, Letterer-Siwe disease, Hand-Schüller-Christian disease, eosinophilic granuloma of the bone and self-healing reticulohistiocytosis. The research is based on the systemic study of Birbeck granules, from their formation to intracytoplasmic development, examining with the electron microscope at regular intervals ultrathin sections derived from biopsies of two cases of Langerhans cell histiocytosis.

Structural characterization of the bronchial epithelium of subjects with chronic bronchitis and in asymptomatic smokers.

A morphometric study was carried out on biopsy specimens taken from 40 smokers (27 with chronic bronchitis and 13 asymptomatic) submitted to bronchoscopy to identify and quantify the possible structural differences between the two groups. The chronic bronchitic group had a mean age of 65.67 years and 57.04 pack-years of smoking, the asymptomatic group had a mean age of 44.69 years and 22.62 pack-years of smoking. 70 biopsy specimens (45 from chronic bronchitics and 25 from asymptomatic smokers), in which large areas of best-preserved and perpendicularly cut epithelium were present, were considered suitable for the study and examined by light and transmission electron microscopy. The mean thickness of surface epithelium (p < 0.001), the number of layers of basal cells (p < 0.001), the intercellular space of the superficial zone of the epithelium (p < 0.05) and the percentage of abnormal bronchial cilia (p < 0.05) were significantly greater in patients with chronic bronchitis than in asymptomatic smokers. No significant difference between the two groups was observed in the thickness of the lamina reticularis of the basement membrane. Goblet cell hyperplasia was more marked in chronic bronchitics than in the asymptomatic smokers (p < 0.001), whereas the frequency of epidermoid metaplasia did not show a significant difference. The morphological study of the bronchial epithelium has allowed the identification of transitional cells, which gives rise to the concept that epidermoid metaplasia may result from conversion of mucous cells. This finding suggests that the different histologic types appearing in lung tumours may originate from one undifferentiated pluripotential stem cell, which is able to differentiate into different histogenetic types.

Gastric metaplasia in duodenal bulb and Campylobacter-like organisms in development of duodenal ulcer.

Multiple biopsies were taken from 50 patients with endoscopic appearance of duodenitis in order to study the relationship between gastric metaplasia in duodenum and the presence of Campylobacter-like organisms (CLOs) and the development of duodenal ulcer disease. Metaplasia was found in at least one biopsy specimen from 46 of the 50 patients; CLOs were seen in 25 of the 50 patients, only in metaplastic areas. In four cases a "transitional epithelium" with the presence of cells containing few apical mucoid granules and absorbent-type brush border as well as goblet cells was seen. In two cases, this epithelium was colonized by a small number of CLOs. Gastric heterotopia appears to be a rare condition.

Patterns of physical modes of contact between Campylobacter pylori and gastric epithelium: implications about the bacterial pathogenicity.

Since the exact mechanisms of the pathogenicity of Campylobacter pylori are not known, we performed an ultrastructural study with the aim of focusing on patterns of possible physical contact between C. pylori and gastric epithelium, and of considering them in relation to the bacterial pathogenicity. Among 20 random consecutive patients referred for routine gastroscopy, we studied ultrathin sections from the 11 patients with Campylobacter-like organisms, and recognized three patterns of physical contact between bacteria and epithelial cells. These patterns seem in accord with published data of C. pylori toxicity, and they could represent different evolutive stages of the infection.

Epithelial morphology of duodenal bulb and Campylobacter-like organisms.

We have carried out ultramicroscopical investigations on 30 patients with endoscopical aspects of congestive or erosive duodenitis associated or not with bulbar ulcer in relation to the presence of Campylobacter-like organisms (CLO), considered as a possible etiologic agent of peptic disease. Bacteria were found in all of the 14 patients with duodenal ulcer and in only five patients without ulcer. The ultrastructural studies provided elements for the evaluation of epithelial colonization of the duodenal bulb by CLO and which may lead to a new interpretation of gastric metaplasia.

Dead fecal yeasts and chronic diarrhea.

The authors report 20 patients in whom a large number of dead or severely damaged yeast cells, supposedly Candida albicans yeasts, were the possible cause of chronic recurrent diarrhea and abdominal cramps. It is suggested that the presence of large numbers of these microorganisms in stools may be considered among the possible etiologies of diarrhea in the 'irritable bowel syndrome'. The possible source of these yeast-like cells, the causes of cell damage, and the mechanisms by which these organisms may induce diarrhea should be investigated.