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At least 541 records · Page 30Linked to original sources
PubMed1978

Osmotic opening of the blood-brain barrier.

The blood-brain barrier at cerebral blood vessels is due to a continuous lining of endothelial cells, which are connected by tight junctions that restrict intercellular diffusion. The endothelium excludes most water-soluble solutes and proteins but supports facilitated stereospecific transport of monosaccharides and large neutral and basic amino acids. The barrier in different species can be made permeable by infusing a hypertonic solution of urea or arabinose into the internal carotid artery. Endothelial cells presumably shrink and tight junctions between them widen to proteins and normally restricted solutes. Thus, intravascular protein tracers such as Evans' blue-albumin, 125I-labelled albumin, horseradish peroxidase (ED 1.11.1.7) and alpha-mannosidase (EC 3.2.1.24) are allowed into the brain, and uptake of [3H] norepinephrine (noradrenaline) is increased more than twofold above a normal rate of accumulation by brain. Osmotic barrier opening to amines has been used to demonstrate their effect on cerebral blood flow from within the brain parenchyma. Osmotic barrier opening is reversible, may be graded with respect to molecular size and is not followed by evidence of brain damage or of brain oedema (when measured two days after hypertonic infusion). Transient cerebral changes probably accompany osmotic opening, however, as glucose uptake and cerebral metabolism of glucose are increased after hypertonic infusion.

Amino Acids↗
PubMed1981

Age as a factor affecting erythrocyte osmotic fragility in males.

Osmotic fragility and erythrocyte dimensions were measured in 40 normal males between the ages of 18 and 78 years. The principal independent variables correlating with osmotic fragility were mean cell haemoglobin concentration and the age of the donor. The age-related effect was shown to increase both the mean fragility of the cells and the variability of the fragilities of the cells within the individual blood sample. The physical basis for the change is an increase in the degree of isometric sphering of the erythrocytes at isotonicity. The change in shape does not appear sufficient to affect capillary perfusion significantly in normal subjects, but suggests that cell shape will increase the vulnerability of the elderly to abnormalities of the microvasculature.

Adolescent↗
PubMed1999

Stability of cyclopropane and conjugated linoleic acids during fatty acid quantification in lactic acid bacteria.

Seven methods commonly used for fatty acid analysis of microorganisms and foods were compared to establish the best for the analysis of lyophilized lactic acid bacteria. One of these methods involves fat extraction followed by methylation of fatty acids, while the other methods use a direct methylation of the samples, under different operating conditions (e.g., reaction temperature and time, reagents, and pH). Fatty acid methyl esters were identified by gas chromatography-mass spectrometry and quantified by on-column capillary gas chromatography. Two reliable methods for the analysis of fatty acids in bacteria were selected and further improved. They guarantee high recovery of classes of fragile fatty acids, such as cyclopropane and conjugated acids, and a high degree of methylation for all types of fatty acid esters. These two direct methylation methods have already been successfully applied to the analysis of fatty acids in foods. They represent a rapid and highly reliable alternative to classical time- and solvent-consuming methods and they give the fatty acid profile and the amount of each fatty acid. Using these methods, conjugated linoleic acids were identified and quantified in lactic acid bacteria.

Bacteria↗
PubMed2003

[Intrathoracic chronic expanding hematoma; report of a case].

A case of a patient with a intrathoracic chronic expanding hematoma presenting as a neoplasm is reported. A chronic encapsulated intrathoracic hematoma is rare condition and is clinically included in a category of chronic hemorrhagic empyemas as a type of chronic empyemas in Japan. The clinical picture of our case suggested a slowly growing tumor. Though needle biopsy was performed, only blood was aspirated. Intraoperative findings revealed a intrathoracic hematoma with a tough capsule. It adhered to the chest wall hardly. Histopathological investigations revealed that the capsule consisted of a collagenous outer layer and a newly vascularized inner layer with fibrosis. Hemosiderin deposits suggested recurrent bleeding from fragile vessels. The mechanisms of hematoma formation and its expanding nature are discussed. The hematoma appeared to have been enlarged by repeated exudation or bleeding from capillaries inside the capsule.

Chronic Disease↗
PubMed1987

The leakage of serum proteins across the blood-nerve barrier in hereditary and inflammatory neuropathies. An immunohistochemical and morphometric study.

The leakage of eight different serum proteins and immunoglobulins across the blood-nerve barrier (BNB) was studied by means of the peroxidase-antiperoxidase method in hereditary and inflammatory neuropathies and graded semiquantitatively with respect to endoneurial staining intensity and distribution. These data were compared with the degree of alterations of the myelinated nerve fibre population evaluated by morphometric analysis. Our series of 18 human sural nerve biopsies included seven hereditary neuropathies (three HMSN I, two HMSN II, two tomaculous neuropathies), nine inflammatory neuropathies (seven polyneuritis, two hypertrophic neuritis) and two normal controls. In HMSN II and in tomaculous neuropathy there was no enhanced endoneurial staining for serum proteins despite of a severe nerve fibre loss, whereas in HMSN I a rise of serum proteins of small and moderate molecular size like albumin and IgG was demonstrated in the endoneurial space indicating an impaired BNB function. Qualitative changes of the BNB with leakage also of high molecular weight proteins were observed in polyneuritis and hypertrophic neuritis, irrespective of the degree of nerve fibre changes. Our results show that fibre loss and alteration of the BNB are not correlated. The unselective leakage of serum proteins through the BNB appears to be a characteristic change in inflammatory neuropathies leading to proteinous edema. With regard to the subperineurial accentuation of the endoneurial edema it will be discussed that the vascular diffusion barrier is more fragile than the perineurial diffusion barrier.

Adolescent↗
PubMed2000

Perivascular smooth muscle alpha-actin is reduced in the endometrium of women with progestin-only contraceptive breakthrough bleeding.

It has been shown that the endometrium of women using progestin-only contraceptives has increased vascular fragility, although the structural basis for this weakness is unknown, as is its role in breakthrough bleeding (BTB). Perivascular cells such as pericytes and vascular smooth muscle cells surround capillaries during the maturation process following angiogenesis, and act to strengthen and stabilize the vessels. The aim of the present study was to quantify endometrial perivascular smooth muscle alpha-actin (alphaSMA) expression in women using Norplant with and without BTB problems, and compare it to controls. Using immunohistochemical techniques, vessels were classified as level 0, 1 or 2 depending on whether perivascular alphaSMA was absent, discontinuous or continuous. In 15 controls the subepithelial plexus had significantly more level 0 vessels than either the functionalis or basalis (61 +/- 4 versus 31 +/- 6 and 37 +/- 4%, P = 0.0006 and P = 0.0007 respectively). In contrast the functionalis and basalis had significantly more level 2 vessels than the subepithelial plexus (20 +/- 3 and 23 +/- 2 compared to 4 +/- 1%, P = 0.0005 and P = 0.000 respectively). The major finding of the study was that in Norplant users, where the relatively atrophic endometrium cannot be divided into different regions, women with BTB problems (n = 20) had significantly more level 0 vessels than those with reduced bleeding (n = 17) (60 +/- 4 versus 46 +/- 4%, P = 0.0302). Norplant users with BTB problems also had a non-significant reduction in level 2 vessels compared to women without bleeding problems (4 +/- 2 versus 11 +/- 4%, P = 0.0667). These results demonstrate that perivascular alphaSMA is reduced around the endometrial vessels of Norplant users with BTB compared to those with no bleeding problems, and strongly support the concept that reduced vascular structural integrity plays a key role in endometrial BTB.

Actins↗
PubMed1996

A comparison of mechanisms underlying disturbances of bleeding caused by spontaneous dysfunctional uterine bleeding or hormonal contraception.

Recent research has not been able to demonstrate close endometrial morphological correlations with specific abnormalities of menstrual bleeding, but has pointed to an increasing number of molecular mechanisms that may be involved in the occurrence of certain forms of abnormal uterine bleeding. Ovulatory and anovulatory dysfunctional uterine bleeding (DUB) and progestogen-related breakthrough bleeding (BTB) are three conditions with quite different clinical characteristics. It is also probable that the local endometrial molecular mechanisms associated with these three menstrual disturbances are quite different. Ovulatory DUB is associated with a series of vascular and haemostatic disturbances that all appear to contribute to increased loss of blood and tissue fluid at menstruation. Anovulatory DUB is associated with obvious disturbances of endometrial histology, vascular morphology and fragility, with variable and increased blood flow. Progestogen-related BTB is associated with a multitude of morphological and functional endometrial changes that appear to relate predominantly to a patchy capillary origin for the bleeding. Many molecular and cellular changes have been observed in all three conditions. It is not yet known whether there is a single, but different, underlying mechanism responsible for these multiple abnormalities in each of the three clinical situations.

Anovulation↗
PubMed1984

Erythrocyte deformability in aging.

Blood viscosity and the deformability and other properties of erythrocytes were compared among 60-, 150-, 320- and 710-day-old rats. Blood viscosity was remarkably higher in the 320- and 710-day old rats than in those 60- and 150 days' old. Measurement by the capillary centrifugal method showed that the deformability of erythrocytes is significantly decreased with age. The increase in blood viscosity with aging could be attributed to the decrease in erythrocyte deformation. Osmotic fragility and the number of higher density erythrocytes also increase with age. The negative surface charge in erythrocytes obtained from old rats was higher than in those from younger rats.

Aging↗
PubMed2002

Targeting of both mouse neuropilin-1 and neuropilin-2 genes severely impairs developmental yolk sac and embryonic angiogenesis.

Neuropilins (NP1 and NP2) are vascular endothelial growth factor (VEGF) receptors that mediate developmental and tumor angiogenesis. Transgenic mice, in which both NP1 and NP2 were targeted (NP1(-/-)NP2(-/-)) died in utero at E8.5. Their yolk sacs were totally avascular. Mice deficient for NP2 but heterozygous for NP1 (NP1(+/-)NP2(-/-)) or deficient for NP1 but heterozygous for NP2 (NP1(-/-)NP2(+/-)) were also embryonic lethal and survived to E10-E10.5. The E10 yolk sacs and embryos were easier to analyze for vascular phenotype than the fragile poorly formed 8.5 embryos. The vascular phenotypes of these E10 mice were very abnormal. The yolk sacs, although of normal size, lacked the larger collecting vessels and had less dense capillary networks. PECAM staining of yolk sac endothelial cells showed the absence of branching arteries and veins, the absence of a capillary bed, and the presence of large avascular spaces between the blood vessels. The embryos displayed blood vessels heterogeneous in size, large avascular regions in the head and trunk, and blood vessel sprouts that were unconnected. The embryos were about 50% the length of wild-type mice and had multiple hemorrhages. These double NP1/NP2 knockout mice had a more severe abnormal vascular phenotype than either NP1 or NP2 single knockouts. Their abnormal vascular phenotype resembled those of VEGF and VEGFR-2 knockouts. These results suggest that NRPs are early genes in embryonic vessel development and that both NP1 and NP2 are required.

Animals↗
PubMed2000

The effects of simultaneous hyperlipemia-hyperglycemia on the resistance arteries, myocardium and kidney glomeruli.

The experimental model of Golden Syrian hamster subjected to concomitant hyperlipemia (diet-induced) and diabetes (by streptozotocin injection) for 24 weeks is characterised by the prevalence of micro- and macroangiopathies. We have used the hyperlipemic-diabetic (HD) hamsters to investigate: a) whether there is an alteration in the reactivity of the resistance arteries (mean internal diameter: 210-250 microm), b) if present, which are the structural and biochemical changes that accompany the functional modifications, and c) to examine the pathomorphological changes induced by the association of hyperlipemia and diabetes on vital organs such as myocardium and kidney glomeruli. To these aims, biochemical assays of plasma components, light- and electronmicroscopy, myographic, morphometric and spectrofluorimetric techniques were used. The mesenteric resistance arteries of HD hamsters exhibited (as compared to similar arteries in normals) a decreased contractile response to noradrenaline (1.86+/-0.35 vs. 2.43+/-0.21), and an impeded endothelium dependent relaxation to acetylcholine (approximately 61.40% vs. approximately 79.80%). The association of hyperlipemia with diabetes induced changes in morphology of the resistance arteries consisting in approximately 10% increase of the intima plus media cross-sectional area, approximately 20% decrease of the vascular lumen area, and approximately 2.85 fold augmentation of the wall to lumen ratio. The resistance arteries exhibited structural modifications of the endothelium (up to 8 copies of Weibel-Palade bodies/endothelial cell), and smooth muscle cells (secretory phenotype), and in the vessels media small calcification cores appeared embedded in a hyperplasic extracellular matrix. The vascular mesenteric bed of the HD hamsters contained approximately 2.30 and approximately 1.30 fold increased concentrations of AGE-collagen and pentosidine, respectively, above the normal values. The HD hamsters displayed also modifications that may be dependent on or may lead to an increase in blood pressure, such as: a) approximately 2 fold increase in the activity of serum angiotensin converting enzyme; b) approximately 4.8 fold enhancement of erythrocytes fragility (as a measure of the oxidative stress); c) left ventricular hypertrophy associated with a progressive disarray of cardiomyocyte contractile fibers, interruptions of the Z bands, and accumulation of collagen-rich extracellular matrix indicative of interstitial fibrosis; d) the kidney glomerular capillaries appeared partially or totally collapsed, with a thickened basement membrane which appeared polymorphic, and in some locations made up of successive layers connected by fine bridges and intercalated nodules; in addition, an increase (approximately 1.50 fold) of the mesangial volume was indicative of glomerulosclerosis.

Acetylcholine↗
PubMed1979

[General pharmacological studies on fosfomycin sodium (author's transl)].

The pharmacological effects of fosfomycin sodium, a new antibiotic agent, were studied on central nervous system, neuromuscular junction, isolated smooth muscles, blood coagulation, red blood cell resistance, body temperature, permeability of skin vessels and IgG and IgE antibody formation in laboratory animals. Fosfomycin sodium inhibited activities on the isolated smooth muscles, elevated body temperature, and increased permeability of skin vessels. Any of these actions, however, was noticeable only when it was administered in higher doses. Except for these above effects, fosfomycin sodium did not show any actions. Consequently, it can be concluded that fosfomycin sodium has no specific pharmacological actions.

Animals↗