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Query: T20B12 .5
 956,342 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The internal plate of the dura mater and arachnoidea of the dob brain was studied by electron microscopy after introducing 0.3--0.5 ml of the autogenous blood into the subdural space. The arachnoidea of the excretory channels and structural elements of the internal plate of the dura mater (cells of the internal covering layer, the collagen fibril and microfibril layer, the wall of the blood capillaries of the internal capillary network) involve the morphological substratum of the liquor-blood barrier-I between the liquor and blood of the blood capillaries of the internal capillary network of the dura mater. It was established that red cells of the subdural space penetrate the thickness of the dura mater, where they concentrate around blood capillaries of the internal capillary network, rather than penetrate into the arachnoidea.
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PMID:[Electron microscopic study of the process of the removal of autogenous blood erythocytes beyond the limits of the subdural space]. 46 29

An aluminum plant on the south bank of the St. Lawrence river, southwest of Cornwall Island, Ontario, Canada, has emitted 0.816 metric tons of fluoride daily since 1973; considerably higher amounts were emitted from 1959 to 1973. The plant has been designated as the "major source of fluoride emissions impacting on Cornwall Island." Chronic fluoride poisoning in Cornwall island cattle was manifested clinically by stunted growth and dental fluorosis to a degree of severe interference with drinking and mastication. Cows died at or were slaughtered after the third pregnancy. The deterioration of cows did not allow further pregnancies. Fluoride concentrations in ash of biopsied coccygeal vertebrae increased significantly with age and were dependent on distance from and direction to the aluminum plant. Fluoride in bone ash of a 7-month old-fetus exceeded 500 ppm; fluoride thus was passed transplacentally. Analyses of fluoride in ash of bones obtained at necropsy of cattle from 4 months of age to 4 to 5 years of age showed increased amounts with age. Cancellous bone retained far higher amounts than cortical bone, a reflection of the normally higher metabolic rate of cancellous bone. Concentrations exceeding 10,000 ppm fluoride were recorded in cancellous bone of a 4-to 5-year-old cow. The target cells for fluoride in chronic fluorosis were shown to be the ameloblasts, the dental pulp cells and the odontoblasts and, in bone, primarily the resorbing osteocytes and also the osteoblasts. Atrophy and necrosis of the ameloblasts were responsible for enamel defects. The existing enamel showed brown discoloration from fluoride deposits. The pulp cells underwent fibrous and osseous metaplasia and necrosis of the ectopic bone occurred. The odontoblasts were atrophic and the dentin showed brown discoloration. The resorbing osteocytes were inactive and osteosclerosis resulted. This was especially pronounced in areas of normally great apposition, i.e. in the metaphyses. The epiphyseal plate became squeezed between petrotic bone and growth was stunted. Resorption of alveolar bone surrounding the deciduous teeth was severely retarded or arrested. A delay in eruption of permanent teeth occurred; it was up to 3.5 years in incisor teeth. Interference with the resorbing osteocytes in fluorotic bone was also demonstrated by loss of collagen birefringency in such bone. Failure of bone resorption also caused retention of trabecular bone in the cortices; this was observed even in a 4-t0-5-year-old cow. In areas where modeling into osteonic bone had begun, fluoride deposits were extremely heavy but this bone showed numerous soft osteons in microradiographs. The toxic effect of fluoride on osteocytes also resulted in the death of the cells. Such osteonecrosis occurred mainly in gnathic bone. There was atrophy of the osteoblasts. Osteopenia thus resulted from osteonecrosis and osteoporosis. Subperiosteal exostoses were not observed in long bones. The degree of fluorosis in Cornwall Island cattle was severe...
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PMID:Industrial fluoride pollution. Chronic fluoride poisoning in Cornwall Island cattle. 46 82

Collagenisation of the space of Disse was systematically assessed to determine its relationship to the clinical and histological manifestations of chronic alcoholic liver disease. Ninety-four chronic alcoholics who had been submitted to biopsy were assessed by clinical manifestations of hepatic dysfunction and by a 17-parameter Combined Clinical and Laboratory Index (CCLI). Liver biopsies were scored for light (LM) and electron-microscopy (EM) abnormalities using a universal scoring system for both. Thirty-five patients with normal liver histology (LM) had an average collagen score of 0.6 +/- 0.1. Twelve cirrhotic patients and 29 with fatty liver, both groups with mild clinical manifestations, did not differ significantly. In 18 cirrhotic patients and five with fatty liver, both groups having severe clinical manifestations, the mean scores were 2.1 +/- 0.8 (P less than 0.02) and 2.5 +/- 0.6 (P less than 0.01) respectively. Collagenisation also correlated with CCLI (P less than 0.001), serum bilirubin (P less than 0.001), serum aspartate transferase (SGOT) (P less than 0.003), and clinical evidence of portal hypertension and histological changes of necrosis, inflammation, and terminal hepatic vein sclerosis. These results suggest that collagenisation of the Disse space may be important in the pathogenesis of alcoholic liver disease.
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PMID:Collagenisation of the Disse space in alcoholic liver disease. 48 62

1. The basement membrane of the crystalline lens of the rat has been found to have the following elastic constants: a Young's Modulus of elasticity of 0.56 +/- 0.38 x 10(6) Nm-2 at low stress and 11.3 +/- 1.9 x 10(6) Nm-2 at rupture, an ultimate stress of 28.8 +/- 4.5 x 10(5) Nm-2, and a maximum percentage elongation of 41.3 +/- 5.8. 2. The ratio of initial thickness of the membrane to the thickness at the point of rupture is 0.271 +/- 0.02 while the similar ratio for volume is 0.461 +/- 0.031. 3. Electron microscopic observations of ultrasonicated fragments of the entire membrane show long filaments in parallel arrays and sheets. The filaments show a periodicity of 3.7 nm and a spacing of 3.5 nm. 4. Electron microscopic observations of collagenase-treated membrane show a poorly staining matrix associated with separate short straight non-periodic filaments some 2.5 nm in diameter. In addition strands project from the ends of the filaments with a diameter of between 0.5 and 1.0 nm. 5. A model is proposed which consists of these filaments, composed of between three and five parallel strands, some 0.8 nm in diameter, wound in a superhelix. 6. The model predicts satisfactorily thickness and volume changes in the membrane when subjected to stress, and also indicates that the filaments would have a similar Young's Modulus of elasticity and ultimate stress to those of collagen. 7. If the basement membrane of the smallest retinal capillaries is subjected to a change of pressure of only 5 mmHg within the vessel lumen, then the membrane is likely to undergo some 30% reduction in thickness.
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PMID:Thickness and volume constants and ultrastructural organization of basement membrane (lens capsule). 50 93

An inherited platelet function defect occurring in a family of basset hounds has been described. The trait is transmitted as an autosomal characteristic and appears to be expressed clinically only in the homozygous state. The characteristics of this platelet defect include:1) marked bleeding tendencies and prolonged skin bleeding times in either male or female dogs.2) normal blood coagulation mechanism.3) adequate numbers of circulating platelets which appear morphologically normal by light microscopy.4) normal whole blood clot retraction.5) deficient in vivo platelet consumption and in vitro platelet retention in glass bead columns.6) defective ADP-induced platelet aggregation in homozygotes, apparently normal ADP response in heterozygotes, and defective collagen-induced platelet aggregation in both.
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PMID:An inherited platelet function defect in Basset hounds. 50 82

This report details the results of studies performed in nine patients with homozygous beta-thalassemia evaluating platelet function and prostaglandin formation. Platelet malonyldialdehyde (MDA) formation in the presence of N-ethyl maleimide (NEM 1 mM) or thrombin (0.5 u/ml) was used as an indicator of platelet prostaglandin synthesis. The data on the nine patients revealed two distinct subgroups of patients. Six of nine thalassemics, demonstrated platelet abnormalities. Their mean bleeding time was 7.5 +/- 2.5 min (1 SD), significantly prolonged (P less than 0.005) when compared to a value of 3.5 +/- 1.0 min in normal controls. MDA formation in the presence of NEM was significantly decreased (P less than 0.005) to 2.41 +/- 0.49 (1 SD) when compared to a control value of 3.24 +/- 0.33 nmoles MDA/10(9) platelets. Similarly, the mean value for thrombin induced MDA was 0.98 +/- 0.18 nmoles which was decreased (P less than 0.02) when compared to a value of 1.26 +/- 0.2 in the controls. Platelet aggregations with adenosine diphosphate (ADP), epinephrine, and collagen were abnormal in all six patients. However, when platelets from these patients were mixed with platelets from donors who had ingested aspirin 2-8 hr before donation mutual correction and secondary irreversible aggregation of the mixture resulted. No mutual correction was observed when the thalassemic platelets were preincubated with aspirin in vitro before mixing with platelets from donors who had recently ingested aspirin. Although the total amount of platelet malonyldialdehyde formed by the thalassemic platelets in response to NEM and thrombin was decreased when compared to normal controls, this reduction was not the cause of the platelet aggregation abnormalities. This appears to be so because the amount of MDA, and, thus, prostaglandin endoperoxides synthesized by these platelets in response to external stimuli was sufficient to cause irreversible aggregation of platelets from donors who had recently ingested aspirin, and were, therefore, unable to synthesize their own endogenous platelet endoperoxides. In the remaining three patients, bleeding times, platelet aggregation, and MDA formation was normal. No correlation was observed between the platelet abnormalities noted and the magnitude of iron overload, presence of fibrin degradation products, liver function abnormalities, or the use of iron chelators in the individual patient. Family studies were normal. Although the platelet dysfunction does not appear to be of major significance in the usual patient with thalassemia major under normal circumstances, antiplatelet aggregating agents should be used with caution. Aspirin inhibits platelet endoperoxide and prostaglandin formation and this effect may potentiate the platelet dysfunction present in some patients with thalassemia major.
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PMID:Platelet dysfunction in homozygous beta-thalassemia. 52 94

Although D-Penicillamine (D-PeA) administration is getting popular in the treatment of rheumatoid arthritis (RA), the mechanism by which D-PeA produced therapeutic effect has not been fully elucidated. D-PeA had been shown to exert an antivitamine B6 effect. However, it has not been precisely confirmed if clinical dose of D-PeA induces vitamine B6 (VB6) deficiency. In order to clarify these questions, biochemical analyses of bone and skin collagens and determination of VB6 content in soft tissues have been performed in the rats administrated therapeutic dose of D-PeA. VB6 deficiency was not observed in the brain and skin from rats fed on normal diet containing D-PeA (13.0--33.5 mg/kg wt). There were no significant changes in the stability of collagen from bone and skin. On the other hand, significant VB6 deficiency and reduced stability of collagen were observed in rats fed on VB6 deficient diet containing the same amount of D-PeA. Aldehyde formation of collagen molecule and cross-link formation of collagen were also found to be suppressed. The same results were obtained from analyses in rats fed on VB6 deficient diet without D-PeA administration. These data indicate that D-PeA is not capable of producing VB6 deficiency in the dosage employed in patients. However, in the treatment for patients who are not taking enough nutrition, the possibility of VB6 deficiency can not be neglected. Once VB6 deficiency is induced by D-PeA administration, severe connective tissue disorder may be produced, since VB6 is required for enzymic activity of lysyl oxidase. It is unlikely that the therapeutic effects of D-PeA in the treatment of RA are produced the the disturbance of collagen cross-link formation as discussed before. Immunologic reactions of D-PeA may play more important role in the improvement of clinical symptoms of this disease.
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PMID:[Effect of D-penicillamine on vitamine B6 and collagen metabolism (author's transl)]. 52 98

Haematoxylin, Alcian Blue-Chlorantine Fast Red (ABCR) and the Ralis osteoid-specific stain were employed to closely follow the histogenesis of the tibia of the embryonic chick so as to provide an accurate description of the onset of ossification. An overview of the major cytological events preceding osteogenesis in the tibia was obtained from hindlimbs of embryos of H. H. (Hamburger and Hambilton, '51) stages 16-26 (2.5-5 days of incubation) stained with ABCR. A description of the cytological changes in the periosteum as it develops from the perichondrium and an analysis of the timing of the onset of osteoid deposition was obtained from the tibiae of accurately aged and staged embryos of H. H. stages 28-32 (5.5-8 days). These tibiae were stained specifically for the detection of osteoid: the freshly-secreted, unmineralized product of fully-differentiated osteoblasts. The perichondrium transformed into a bi-layered periosteum at H. H. late stage 29 (6.5 days) while osteoid was first detected adjacent to the hypertrophic cartilage of H. H. stage 30 (6.5-7 days) tibial diaphyses. These results, correlated with the immunoflourescent studies of Von der Mark et al. ('76a,b), which revealed the presence of Type I (bone-type) collagen-synthesizing cells in the perichondria of tibiae from embryos of H. H. stage 28 (5.5-6 days), demonstrated that the onset of determination of cells for osteogenesis and the cytodifferentiation of the periosteum are not temporally coupled.
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PMID:The timing of the onset of osteogenesis in the tibia of the embryonic chick. 52 94

The interaction of bovine platelets with bovine glomerular basement membrane has been studied by aggregometry, transmission and scanning electron microscopy and measurement of [3H] serotonin release. In the absence of added calcium platelets adhere to basement membrane but fail to undergo the release reaction or aggregation. In the presence of 0.2-0.5 mM calcium release of serotonin and complete aggregation of the platelets are observed when sufficient basement membrane is present. Platelets were strongly adhered to the basement membrane surface, the platelet surface in the aggregates closely following the surface of the basement membrane. Platelet morphology in aggregates with basement membrane closely resembled that of platelets from collagen-induced aggregates. Basement membrane differed from collagen in its requirement for calcium for the aggregation and release reactions. In addition purified basement membrane was 1.5-3 fold less active on a weight basis than bovine tendon collagen in promoting aggregation.
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PMID:Interaction of bovine platelets with bovine glomerular basement membrane. 54 30

The cuticle (0.15 to 0.5 microns thick) of the microscopic free-living nematode Panagrellus silusiae was isolated intact by incubating worms with 1% sodium dodecyl sulfate at 37 degrees C overnight. After shearing and further treatment with detergent, electron microscopy revealed that the cuticular pieces were free of contaminating material and retained their characteristic in situ ultrastructure. From amino acid determinations, the cuticle is collagen-like with high levels of glycine (approximately equal to 31 residue %), proline (approximately equal to 20 residue %) and alanine (approximately equal to 21 residue %) although the hydroxyproline (2.6 residue %) content is low. Half-cystine (approximately equal to 1 residue %) is present in purified cuticles. Treatment with 8 M guanidine hydrochloride-2% beta-mercaptoethanol can solubilize more than 85% of the cuticular preparation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the solubilized cuticles from juvenile, adult and old dead worms revealed, at least, 18 discrete components. Estimated molecular weights ranged from about 26 000 (peak 1) to 250 000 (peak 18).
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PMID:Isolation and characterization of the cuticle from the free-living nematode Panagrellus silusiae. 54 35


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