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Biomedical subjects

R More

Publications and source records attributed to R More.

36 records · Page 2Linked to original sources
PubMed1983

T-2 toxin-induced pathology in the hearts of rats.

T-2 toxin is the major lethal component of several Fusarium fungi implicated in diseases of man and animals. We report here on the histological and ultrastructural changes in hearts of rats given i.p. single large or repeated small doses of T-2 toxin. One, 2 and 3 days after a single large dose, there were lesions in most hearts. They consisted of interstitial oedema, focal cellularity and damage to single or groups of myocytes. The small intramural coronaries were constricted, swollen and sometimes disrupted. After 7 days, most of the changes subsided. In rats killed 1 or 2 months after the last of 10 daily injections of T-2 toxin, cardiomyopathy-like changes were seen with hypertrophy, focal fibrosis and abundant cellularity especially in the subendocardial regions of the left ventricle. The findings, although non-specific, indicate that T-2 toxin is cardiotoxic.

Animals↗
PubMed1982

Studies of platelets with heavy metal impregnation techniques.

Various methods of heavy metal impregnations were performed on human platelets. The optimal technique consisted of glutaraldehyde fixation, incubation in warm uranyl acetate at a pH of 3.5, followed by a double solution of lead and copper, and finally overnight immersion in cold osmium tetroxide. Semi-thin sections, viewed at 90 kV, revealed three types of platelets: (1) 'reticular' cells, with a prominent tubular network and very dark granules in a pale cytoplasm; (2) 'dark' cells, with an electron-dense cytoplasm; and (3) 'pale' cells, with microvesicles and non-staining granules. Pre-treatments with EGTA, aspirin and various platelet activators altered the appearances and proportions of the three cell types. A cell-partitioning two-phase polymer system showed that the sub-grouping is related to surface membrane properties, the cells retained in the top phase being exclusively type 2 'dark' cells. The changes in cell type distribution produced by activation show that metal impregnation may be a useful method for studying structure-function correlations in platelets.

Aspirin↗
PubMed1982

Enhancement of human muscle growth in diffusion chambers by bone marrow cells.

Samples of minced human muscle were cultured in millipore diffusion chambers incubated in the peritoneal cavities of mice. In about half the chambers the minced muscle samples were mixed with autogenous bone marrow cells which lead to improved myogenic growth. A similar but less marked effect was produced by mononuclear cells from the patients' blood. No growth enhancement occurred when the muscle and marrow cells were separated by a filter in double chambers. In addition to accelerated myogenesis, the chambers with added bone marrow cells had a much lower incidence of infection. This work may have practical clinical implications for the treatment of muscle injuries. Local implantation of autogenous marrow cells (+/- minced muscle) may prove useful in improving myogenic regeneration.

Adolescent↗
PubMed1981

Diffusion chamber cultures of muscle from patients with scoliosis.

Explants from paraspinal muscles of patients with scoliosis were cultured in Millipore diffusion chambers placed in peritoneal cavities of mice. Three and four weeks of incubation produced a predominantly myogenic growth. Cell counts done on paraffin sections and on dissociated cells from the chambers showed that explants from the concavity of the spinal curvature grew better than those from the convexity. Since cells from injured muscles, when transplanted or cultured, are known to grow better than those from healthy control tissue, these findings support our previous morphologic observations that in idiopathic scoliosis concave muscles are more involved by the disease process. Secondary subculture of the chamber contents by conventional methods produced myotubes within one to two weeks. The relative ease of diffusion chamber muscle culture should make the method useful to laboratories that are not specifically equipped for tissue culture work.

Adolescent↗
PubMedDate not supplied

T-2 toxin effect on isolated perfused rat hearts.

T-2 toxin is the major lethal component of several Fusarium fungi implicated in the disease of man and animals. We used isolated rats hearts to test the T-2 toxin cardiotoxicity. Electrodynamics and ultrastructural parameters were studied. The main changes consisted of decreased contractility and electrocardiographic abnormalities without much effect on heart rate or QRS and QT intervals. Ultrastructurally, swelling of myofibers and their mitochondria occurred and damage to the plasma membrane was seen. It is possible that the T-2 effect is mediated through soluble thiol to cause cytoplasmic calcium decrease and loss of plasma membrane integrity.

Animals↗
PubMedDate not supplied

Collagen fiber architecture of bovine pericardium.

Small-angle light scattering (SALS) was used to quantify the collagen fiber architecture of 12 bovine pericardium (BP) specimens overlying the right and left anterior surfaces of the heart. The collagen fiber architecture was described in terms of preferred collagen fiber directions, volume fractions (Vf), and degree of orientation. To explore the relationship between BP collagen architecture and mechanical anisotropy, biaxial mechanical tests were performed on two specimens chosen for their extremes of collagen fiber architecture. About 38% of the SALS test locations showed the occurrence of two distinct collagen fiber populations, with the primary population Vf typically 90%. Structurally, the left anterior specimens appeared to be the most homogeneous, with an overall preferred direction close to the circumferential direction of the heart. The right side specimens were inconsistent, with a broad range of fiber orientations. The direction of greatest stiffness was consistent with the underlying collagen fiber architecture. Overall, these results suggest that 1) the mechanical behavior of BP is quantitatively consistent with its collagen fiber architecture; 2) the variability of BP mechanical anisotropy is caused by variations in collagen fiber preferred directions; and 3) the left anterior side of the bovine pericardial sac might be a good material selection site for bioprosthesis fabrication.

Animals↗
PubMedDate not supplied

Quantifying the effect of locally delivered anticoagulant drugs: modification of an in vivo model of venous thrombosis.

Increasingly, attention is focusing on the local delivery of antiplatelet and fibrinolytic therapy as a means of preventing intravascular thrombosis. A simple, reproducible model of thrombosis, based upon vascular damage is needed to test these agents in vivo. We have therefore modified a rat vena cava model of venous thrombosis based upon vascular injury and stasis. Wistar rats are anaesthetised, the inferior cava dissected free and a segment isolated by slings distally above the iliacs and proximally above the left renal vein. All other tributaries are ligated. Vascular injury is induced by externally applying soft-jaw clamps for 5 min. Agents to be tested are introduced into the isolated segment via a left renal vein cannula left in situ for 15 min and then flushed from the cava. Blood is allowed to refill the segment, all remaining slings are tied and the animal left for 30 min before being killed. The cava is then opened and thrombus removed and weighed. Scanning electron microscopy of the cava after clamping shows areas of normal endothelium interspersed with areas of denuded endothelium and exposed subendothelial connective tissue. Histological and immunohistochemical staining indicates the thrombus is composed of red cells, platelets and fibrin. The model was validated by assessing the effects of 2 different doses of locally delivered tissue-type plasminogen activator (tPA). The mean weights of thrombus were [mg (SD)]: Control (saline; n = 8) 39.0 (8.73), tPA 0.01 mg/ml (n = 6) 45.5 (10.56) and tPA 1 mg/ml (n = 8) 3.5 (3.4). Comparing 1 mg/ml tPA vs. 0.01 mg tPA vs. control, p < 0.001 (Mann-Whitney test).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗