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Results for “Capillary Fragility”

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At least 325 records · Page 18Linked to original sources
PubMed2007

[Extracorporeal shock-wave lithotripsy induced ultrastructural changes to the renal parenchyma under aspirin use. Electron microscopic findings in the rat kidney].

BACKGROUND: The risk of hemorrhagic complications after extracorporeal shock-wave lithotripsy (ESWL) increases in patients with aspirin intake, but the hematoma-inducing mechanism has not been understood completely at the ultrastructural level. METHODS: The effect off shock-waves on the kidneys of male Wistar-rats (n=24) was investigated in an experimental setting using a special ESWL device. Ultrastructural examination was performed by light-, transmission electron- and scanning electron microscopy. RESULTS: Shock-wave induced tissue damage appeared in all kidneys independently of aspirin intake. Endothelial detachment, lethal cell injury, gaps and mechanical disruption of the glomerular basement membrane were regularly found. After 1 week, repair processes were completed with evidence of permanent fibrosis in some cases. CONCLUSIONS: ESWL can induce modest as well as fatal damage to renal tissue cells. Therefore, after an ESWL-induced hematoma a second ESWL should not be performed within 1 week of the first treatment.

Animals↗
PubMed1998

Capillaries with fenestrations around regenerating muscle fibers in the soleus muscle of the dystrophic (dy) mouse.

To investigate the morphological changes in capillaries around regenerating muscle fibers in the dystrophic (dy) mouse, we examined capillaries in the soleus muscles of 30-day-old control and dy mice by electron microscopy. In the control mice, the intramuscular capillaries were continuous. In the dystrophic mice, the muscles contained degenerative muscle fibers and many small muscle fibers regenerating after necrosis; these fibers had centrally located nuclei. The capillaries in the dy mice were mostly continuous, but some had a narrow vascular lumen around regenerating muscle fibers, possibly indicating newly formed capillaries. Moreover, about 20% of the capillaries with a narrow vascular lumen had a small number (less than five) of fenestrae bridged by a single-layered diaphragm. These findings suggest that capillary networks around muscle fibers regenerating after necrosis are remodeled by newly formed capillaries, and some of these capillaries have fenestrae in the endothelium to increase the supply of nutrients and oxygen to the regenerating muscle fibers.

Animals↗
PubMed1987

Development and progression of chronic renal disease: can it be prevented or attenuated?

Following its initiation, renal disease tends to progress relentlessly to end stage, necessitating dialysis or transplantation or causing death. Studies have shown that metabolic, hematologic and hemodynamic adaptations by the damaged kidney underlie the progressive nature of the disease. This review underscores the hemodynamic maladaptations and consequences and the evidence that suggests that glomerular hypertension is a necessary accompaniment to renal damage. The evidence reviewed indicates that high pressure develops in fragile glomerular capillaries after loss of a critical amount of renal mass and causes progressive sclerosis and destruction of remaining nephrons. This maladaptive renal response ensures progressive destruction in a variety of renal diseases including diabetes mellitus. Reduced protein intake and converting enzyme inhibitor therapy may prevent or attenuate the progression of these diseases.

Animals↗
PubMed1978

Experimental lead encephalopathy in the suckling rat: concentration of lead in cellular fractions enriched in brain capillaries.

Five-day old rats subjected to short-term (2-day) lead exposure by gastric gavage of aqueous lead acetate at the highest non-lethal dosage (1mgPb/g body weight/day) developed a hemorrhagic encephalopathy. Capillaries and microvessels isolated from brains of these rats showed abnormal morphology consisting of an increased number of irregularly dispersed endothelial nuclei and swollen, vacuolated endothelial cells. Lead was concentrated in isolated brain capillary-microvessel fractions, as demonstrated by both atomic absorption and 210Pb tracer methods. When lead exposure was continued for 20 days (at the maximal dosage regime compatible with a 60% survival rate), the rats recovered from the initial encephalopathy and capillaries and microvessels isolated from brains of these rats appeared morphologically normal. This recovery occurred despite continued high levels of lead in the blood and in the isolated capillary-microvessel fractions, suggesting that, as capillary endothelial cells mature, they are able to adapt to the presence of large amounts of lead.

Animals↗
PubMed1978

Basal normoglycemia attained with chlorpropamide in mild diabetes.

Sixteen adult-onset diabetics, who were thought by current criteria to be well controlled on diet alone, had substantially elevated overnight, basal plasma glucose concentrations. Chlorpropamide had a sufficiently prolonged stimulatory effect on the beta cells such that normal basal plasma glucose levels were obtained in 13 patients. Both basal plasma C-peptide levels and the C-peptide response to meals became normal, with improved postprandial glycemia. Diurnal plasma triglyceride levels were reduced. Plasma growth hormone levels were normal both before and after therapy. When diet alone is insufficient to maintain basal normoglycemia in mild diabetes, chlorporpamide is as effective as basal insulin supplements in producing normal basal plasma glucose levels.

Blood Glucose↗
PubMed1994

Comparative aspects of the strength of pulmonary capillaries in rabbit, dog, and horse.

In previous studies of rabbit and dog lung, we demonstrated stress failure of pulmonary capillaries at high transmural pressures (Ptm). The Ptm necessary to elicit stress failure was 40 cmH2O higher in dog than rabbit, and the total blood-gas barrier (BGB) thickness was greater in dog than rabbit. This suggests that stress failure may be related to BGB thickness, and is consistent with the Laplace relationship which states that wall stress is proportional to capillary radius but inversely proportional to wall thickness. In the present studies, we compared BGB thickness and an index of capillary radius in lungs from 3 rabbits, 3 dogs, and 2 horses perfusion fixed at a Ptm of approximately 30 cmH2O. Thicknesses of the BGB were measured at right angles to the barrier at random points on the capillary wall determined by test line intersections. Capillary radius was determined from the mean of major and minor axes measured on electron micrographs. Capillary pressure for failure in the horse was taken to be the mean of pulmonary arterial and left atrial pressures observed in galloping thoroughbreds known to develop exercise-induced pulmonary hemorrhage, although the actual pressure required for failure may be less than this. Average capillary radii were 3.6, 3.4, and 3.2 microns for rabbits, dogs, and horses, respectively. We found that the BGB was thinnest in the rabbit, intermediate in the dog, and thickest in the horse. Calculated capillary wall stress values for the median total BGB thickness at a nominal Ptm of 30 cmH2O were 2.5 x 10(4), 1.7 x 10(4), and 1.5 x 10(4) N.m-2 for rabbits, dogs, and horses, respectively. This species ranking fits with the pressures required to cause stress failure which are approximately 50, 90, and 130 cmH2O in rabbit, dog, and horse, respectively. We conclude that the differences in capillary radius of curvature and BGB thickness account for some of the observed differences in Ptm necessary to cause stress failure. However, other factors may also be important in determining the strength of the BGB.

Animals↗
PubMed1977

Applications of a simple theory of the acoustic motion of fibrous networks in viscous media.

The rupture of blood capillaries in the spinal chords of rats by pulsed ultrasound and the motion of fibrils in the corneal stroma are analysed in detail in terms of a simple theory of wave propagation in a fibrous network permeated by a viscous medium. The advantages of inelastic light scattering experiments in connection with studies of ultrasound are emphasized.

Animals↗
PubMed1991

A comparison of template bleeding time with mucosal petechiometry as a measure of the platelet function defect induced by aspirin.

The object of this study was to assess the value of mucosal petechiometry as a useful method of measuring the haemostatic defect induced by aspirin. The template bleeding time was done for comparison. The results indicated that mucosal petechiometry did not measure the haemostatic defect induced by aspirin and that aspirin-induced alterations in platelet function were not important in the development of petechiae in healthy subjects.

Adult↗
PubMed1984

Protective effect of quercetin and rutin on photosensitized lysis of human erythrocytes in the presence of hematoporphyrin.

Photosensitized hemolysis of human erythrocytes by hematoporphyrin was suppressed by flavonols such as quercetin and rutin at submillimolar concentrations. The suppression of photohemolysis was accompanied by inhibition of lipid peroxidation by the reagents. Quercetin and rutin were photooxidized in the presence of hematoporphyrin and the photooxidation was partially suppressed by 1 mM NaN3, a quencher of singlet molecular oxygen. Flavonols were also oxidized by radicals formed during degradation of lauroyl peroxide. These results indicate that flavonols can function as antioxidants in biological systems by terminating radical chain reactions and removing singlet molecular oxygen. A pharmacological function of flavonols, decrease of the increased permeability and fragility of capillary, was discussed in relation to their antioxidative functions.

Erythrocytes↗