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Biomedical subjects

R Yarom

Publications and source records attributed to R Yarom.

At least 19 recordsLinked to original sources
PubMed1992

Myocardial dystrophin immunolocalization at sarcolemma and transverse tubules.

Using monoclonal antibodies against two different regions of the helical rod part of dystrophin, we have localized dystrophin on both plasma membrane and transverse tubules in cardiac muscle of man and several animal species. The staining persisted after experimental ischaemia, and was observed in long-standing heart disease. No immunostaining was seen at the intercalated discs. In skeletal muscle the same two antibodies stained only the plasma membrane.

Animals↗
PubMed1992

Human coronary microvessels in diabetes and ischaemia. Morphometric study of autopsy material.

The objective of this study was to test the hypothesis that excessive severity of ischaemic heart disease in diabetics is due, in part, to capillary inadequacy. Sections from autopsied hearts of diabetic patients with and without myocardial infarction as well as from those of patients with infarcts and no diabetes were used for morphometric studies of intramural microvessels in areas without infarction. Normoglycaemic patients with normal hearts were also examined. Two to five transverse sections from each of 44 hearts (stained with methenamine silver) were examined for capillary numerical density, capillary to myofibre ratios, and myofibre diameters. Averages for each case and totals for each group were calculated and compared. Normoglycaemic patients with infarcts had increased morphometric values. Diabetics with infarcts had significantly lower capillary densities than the other groups. In conclusion, it is suggested that in diabetes there is an inadequate ischaemia-induced, reactive angiogenesis. This may contribute towards increased myocardial vulnerability in further ischaemic injury and perhaps to diabetic cardiomyopathy.

Adult↗
PubMed1992

Degenerative changes in the A375 melanoma line induced by transforming growth factor beta 1.

A375 human melanoma cell cultures grown in the presence of TGF beta contained greatly reduced cell numbers and exhibited drastic alterations in cell morphology compared to the control cultures. Preincubation of the cells with the cytokine for only 18 h was sufficient to induce these changes irreversibly. Examination of TGF beta-treated cells in the electron microscope revealed large numbers of lipid-filled vacuoles in the cytoplasm, greatly contracted nuclei and some loss of the otherwise abundant microvilli. Thus TGF beta may have a direct toxic effect on the A375 melanoma cells.

Cell Count↗
PubMed1992

Effect of ionizing radiation on neuromuscular junctions in mouse tongues.

Radiation damage to the neuromuscular junctions (NMJs) in mouse tongues was studied using local x-irradiation of the tongues with the rest of the body shielded. Transmission electron microscopy (TEM) revealed no significant morphological changes in the fine structures and organelles of the NMJs given 4 Gy. A dose of 8 Gy produced degenevative morphological changes associated with oxon terminal sprouting as early as 2 and 7 days following irradiation. Subsequently, 1-11 weeks later, severe degenerative changes were observed. The number of mitochondria was significantly decreased with increased occurrence of degenerative membranal features. The number of synaptic footplates without terminals or with multiple small terminals within one groove increased gradually with time. Most of these pathological changes persisted for at least 3 months after irradiation. However, the myofibres, blood vessels and interstitial cells appeared to be unaffected throughout the period of follow-up. The present study substantiates our previous reports of ageing-like changes in the tongues' NMJs induced by their excessive exposure to free radicals.

Animals↗
PubMed1991

Coronary capillaries in patients with congestive cardiomyopathy or angina pectoris with patent main coronary arteries. Ultrastructural morphometry of endomyocardial biopsy samples.

BACKGROUND: The coronary microvasculature may be abnormal even in the presence of angiographically normal epicardial arteries. Abnormalities of small coronary vessels have been invoked as a cause of angina. METHODS AND RESULTS: To quantitatively evaluate the morphology of capillaries in patients with idiopathic dilated cardiomyopathy (DCM) or the syndrome of angina and small vessel disease (SVD), we performed electron microscopic morphometry of capillaries in right ventricular biopsy samples taken from 32 patients. Ten had angina, normal epicardial coronary arteries, and evidence for SVD; 12 had DCM; and 10 had normal hearts. In patients with DCM, the ratio of microvessels to myocytes was not different than that of controls (0.49 +/- 0.06 versus 0.51 +/- 0.05). Mean cross-sectional areas of the capillaries (lumen plus wall) and lumen were significantly greater than those of controls (45.3 +/- 15.1 versus 22.7 +/- 8.3 micron 2, p less than 0.001; 17.6 +/- 6.9 versus 11.6 +/- 6.2 micron 2, p less than 0.05, respectively). Fibrous content of the myocardium, as assessed by quantitative light microscopy, was significantly increased (16.3 +/- 3.3% versus 5.0 +/- 2.4%, p less than 0.001). In contrast, in patients with SVD, the capillary-to-myocyte ratio was reduced (0.33 +/- 0.08, p less than 0.001). Although mean cross-sectional areas of the entire capillary (32.4 +/- 19.7 micron 2) and the lumen (8.9 +/- 7.8 micron 2) were not statistically different than those of controls, there was an absence of capillaries less than 15 micron 2 in cross-sectional area, and the frequency distribution of the lumen area was skewed to the left. Swollen endothelial cells frequently encroached upon the lumen. There was a mild increase in fibrous content (9.5 +/- 3.7%, p less than 0.05). CONCLUSIONS: Enlarged capillaries and a normal ratio of capillaries to myocytes appear to be features of DCM. Of the patients with SVD, there was both a relative lack of capillaries and capillary lumen narrowing from swollen endothelium. These changes may induce ischemia and angina and may result in mild fibrosis.

Adult↗
PubMed1990

Myocardial pathology in rats exposed to prolonged environmental heat.

STUDY OBJECTIVE: The aim was to assess the role of continuously high environmental temperature in the genesis of tropical cardiomyopathies. DESIGN: Rats were kept in a climatic chamber at a constant temperature of 34 degrees C (40% relative humidity) for 1 or 2 months. Controls were kept at 24 degrees C. The hearts, either taken directly from the animals or following Langendorff perfusion, were then examined by light and electron microscopy. EXPERIMENTAL MATERIAL: 69 rats of two different strains, aged about 1 month, were used as the study group. There were 32 suitable controls. MEASUREMENTS AND MAIN RESULTS: The weights of the heated rats and their hearts were lower than controls but the body to heart weight ratio was unchanged. The maximum pressure developed by the left ventricle was higher. With light microscopy, focal necrosis, lymphoid and mast cell infiltrations, fibrosis, and occasional calcifications were seen in most heat exposed rats. With electron microscopy most myocytes appeared normal when taken from whole animals. The additional trauma of heart suspension or hypo-osmolar perfusion caused severe membrane related pathology, while controls remained unaffected. CONCLUSIONS: Prolonged exposure to heat produces focal cellular reactions and disturbance of the myocyte membrane. The pathogenesis of the changes is as yet uncertain. It may be multifactorial and include calcium and/or oxygen derangements mediated by mast cells, catecholamines, hypothyroidism, and heat shock proteins.

Animals↗
PubMed1990

Mildly dilated congestive cardiomyopathy. Use of prospective diagnostic criteria and description of the clinical course without heart transplantation.

Prognosis in classically described dilated congestive cardiomyopathy has been reported to be related to ventricular size. Mildly dilated congestive cardiomyopathy (MDCM) has been defined as end-stage heart failure of unknown etiology (New York Heart Association class IV, left ventricular ejection fraction less than 30%), occurring with neither typical hemodynamic signs of restrictive myopathy nor significant ventricular dilatation (less than 15% above normal range). The present study includes follow-up in 12 nontransplant patients. In the first 4 months after diagnosis, two patients improved and are living, and two showed cardiac dilation and clinical deterioration and died. Six of the remaining eight with persistent MDCM died (four with intractable heart failure and two, sudden deaths) without change in ventricular size before death, despite medical therapy over 20 +/- 8 months. Eight comparable transplanted patients with persistent MDCM demonstrated improved total survival by life table analysis (p less than 0.05). A family history of congestive cardiomyopathy was found in nine of 16 patients (56%) with persistent MDCM. Nontransplant patients were older (p less than 0.02), but other findings were similar in the two groups. Endomyocardial biopsies available in 14 of 16 cases showed little or no myofibrillar loss in spite of severe hemodynamic impairment. The degree of myofibrillar loss did not correlate with hemodynamic parameters but showed good correlation with left ventricular size, that is, five of six patients with no myofibrillar loss had normal ventricular size, whereas all eight patients with mild myofibrillar loss had mild cardiomegaly (p less than 0.002). Our current experience suggests a somewhat variable but negative prognosis after prospective diagnosis of MDCM, with poor survival in patients with persistence of the original diagnostic features during follow-up. Preservation of heart size in MDCM is probably related to lack of significant myofibrillar loss. Thus, irrespective of heart size or myofibrillar preservation on biopsy, heart transplantation should be strongly considered in MDCM if signs of severe cardiac dysfunction persist despite therapy.

Adult↗
PubMed1990

Down syndrome clinical symptoms are manifested in transfected cells and transgenic mice overexpressing the human Cu/Zn-superoxide dismutase gene.

Down syndrome (DS), the phenotypic expression of human trisomy 21, is presumed to result from overexpression of certain genes residing on chromosome 21 at the segment 21q22-the Down locus. The "housekeeping" enzyme CuZn-superoxide dismutase (CuZnSOD) is encoded by a gene from that region and its activity is elevated in DS patients. To investigate the possible involvement of CuZnSOD gene dosage in the etiology of the syndrome we have developed both cellular and animal models which enabled us to investigate the physiological consequences resulting from overexpression of the CuZnSOD gene. 1. Rat PC12 cells expressing elevated levels of transfected human CuZnSOD gene were generated. These transformants (designated PC12-hSOD) closely resembled the parental cells in their morphology, growth rate, and response to nerve growth factor, but showed impaired neurotransmitter uptake. The lesion was localized to the chromaffin granule transport mechanism. We found that the pH gradient (delta pH) across the membrane, which is the main driving force for amine transport, was diminished in PC12-hSOD granules. These results show that elevation of CuZnSOD activity interferes with the transport of biogenic amines into chromaffin granules. Since neurotransmitter uptake plays an important role in many processes of the central nervous system, CuZnSOD gene-dosage may contribute to the neurobiological abnormalities of Down's syndrome. 2. As an approach to the development of an animal model for Down syndrome, several strains of transgenic mice that carry the human CuZnSOD gene have been prepared. These animals express the transgene in a manner similar to that of humans, with 0.9 and 0.7-kilobase transcripts in a 1:4 ratio, and synthesize the human enzyme in an active form capable of forming human-mouse enzyme heterodimers. CuZnSOD activity is increased from 1.6 to 6.0-fold in the brains of four transgenic strains and to an equal or lesser extent in several other tissues. 3. To investigate the possible involvement of CuZnSOD gene dosage in the neuropathological symptoms of Down's syndrome, we analyzed the tongue muscle of the transgenic mice that express elevated levels of human CuZnSOD. The tongue neuromuscular junctions (NMJ) in the transgenic animals exhibited significant pathological changes, namely, withdrawal and destruction of some terminal axons and the development of multiple small terminals. The ratio of terminal axon area to postsynaptic membrane decreased, and secondary folds were often complex and hyperplastic. The morphological changes in the transgenic NMJ were similar to those previously seen in muscles of aging mice and rats as well as in tongue muscle of patients with Down's syndrome.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1979

Electron microscopic x-ray microanalysis in pathology: current status.

Electron microscopic X-ray microprobe analysis is very suited to pathological investigations. It may lead to a better understanding of the relationship between structure and function in disease processes. It may also help to detect localized abnormalities before the appearance of morphological changes. This methodology may thus contribute to earlier diagnoses and detection of the carrier state, and may aid in the study of reactions to injury and therapy.

Electron Probe Microanalysis↗
PubMed1979

Muscle pathology in idiopathic scoliosis.

Muscles from patients with scoliosis were studied to determine the possible relationship between neuromuscular disease and idiopathic scoliosis. Biopsies taken from the paraspinal musculature, the gluteus maximus and other sites were examined and compared with control specimens taken from patients undergoing spinal surgery for other disorders. Morphological and morphometric examinations by light and electron microscopy revealed a wide range of pathological changes and an alteration in the normal distribution of fiber types in most muscles. Changes were mainly nonspecific, but one unusual feature in idiopathic scoliosis but not in the other types of scoliosis consisted of type I fiber atrophy in paraspinal and deltoid muscles of the concave side paraspinal muscle, the site of the maximum morphological changes. The localized muscle changes, which are disease and not deformity related, suggest that idiopathic scoliosis is a separate disease entity and that the central nervous system may be involved in its genesis.

Adolescent↗
PubMed1978

Electron microscopic X-ray microanalysis of localized element concentrations in human cardiomyopathies: a pilot study.

The elemental content in localized cellular regions of human myocardial biopsy specimens was studied by electron microscopic x-ray microanalysis. The elements detected were phosphorus, sulfur, chlorine, calcium, and zinc and occasionally tracrs of iron and copper. Nucleoli and heterochromatin contained the highest concentrations of phosphorus and calcium, whereas sulfur was prominent in sarcomeres, dark mitochondria, and secondary lysosomes. Dark mitochondria often had more phosphorus, sulfur, and calcium than swollen, paler ones.

Adult↗
PubMed1978

X-ray fluorescence analysis of muscles in scoliosis.

X-ray fluorescence spectrometry was used to determine calcium, copper, and zinc concentrations in paraspinal and gluteal muscles obtained during spinal surgery from patients with scoliosis. Samples of 1-3 mg were sufficient to demonstrate that calcium was higher in idiopathic than in other forms of scoliosis or in normal control muscles. It is suggested that a calcium-related neuromuscular defect could be an important factor in the genesis of idiopathic scoliosis.

Calcium↗
PubMed1977

Zinc distribution in injured myocardium. EMMA-4 examinations of dogs' hearts after coronary ligation.

Electron microscopic X-ray microanalysis and atomic absorption spectrophotometry were used to determine changes in zinc concentration after myocardial ischemic injury by coronary ligature in dogs. The zinc concentration increased in the damaged myocardium especially in specific intracellular locations identified by means of the microprobe. It was concluded that the selective zinc augmentation was related to proliferative and biosynthetic reactive processes in the myocardium.

Animals↗
PubMed1977

Myosin degeneration in a congenital myopathy.

In a muscle biopsy specimen from a baby girl with hypotonia, there was the ultrastructural finding of selective myosin degeneration in some myofibers. The sarcomeres were either well aligned or completely distorted. Excessive glycogen, fiber and fibril splitting, and occasional aggregates of vesicles were the other abnormalities present.

Female↗