Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0344329 (collapse)
 28,634 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The molecular area, collapse pressure, and surface potential of gangliosides obtained by different methods were systematically compared in monolayers at the air-water interface. Different values of these parameters are obtained depending on the purification procedure employed for the isolation of pure gangliosides. This is due to impurities (such as peptidaceous material) that remain in different amounts in the various preparations and that modify the ganglioside surface behavior. Routine purity checking by HPTLC analysis of gangliosides usually fails to reveal these impurities. On the other hand, even if the monolayer technique cannot identify the nature or amount of contaminants, it is extremely sensitive to reveal alterations of the surface molecular parameters caused by relatively small amounts of other components coextracted with the ganglioside or adventitiously introduced with the solvents or subphases employed. This is a serious problem for the obtention of correct and reproducible values of such important parameters as the molecular area of gangliosides, their electrostatic potential in oriented interfaces, and their interactions with other lipids and proteins. A procedure leading to consistent molecular parameters that remain reproducible after several repurification cycles is to perform an alkaline treatment on previously purified gangliosides species with NaOH, this is followed by dialysis against bidistilled water, rechromatography on DEAE-Sephadex A25, silicic acid or Iatrobeads, and Sephadex LH-20 columns; repurified gangliosides are stored in chloroform-methanol-0.01 M NaOH (60:30:4.5).
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PMID:Molecular parameters of gangliosides in monolayers: comparative evaluation of suitable purification procedures. 193 17

Effects of betaxolol, a cardioselective beta-adrenoceptor antagonist, on blood pressure and hypertensive complications in stroke-prone spontaneously hypertensive rats (SHRSP) were investigated. Betaxolol was provided in a dose of 33 +/- 1.8 mg/kg/day, orally in drinking water, throughout the experimental period. The chronic treatment with betaxolol inhibited the development of hypertension in SHRSP and reduced values of blood urea nitrogen, creatinine, total cholesterol, free cholesterol, triglyceride, phospholipid and HDL-cholesterol in serum. Treatment with betaxolol apparently inhibited the incidence of hypertensive lesions such as cardiac fibrosis, mesenteric vasculitis, proliferative and/or necrotic vasculitis and glomeruli showing collapse or vasculitis in the kidneys. To shorten the time before the onset of hypertension and the subsequent stroke, SHRSP were kept on a SP diet containing 0.39% Na instead of the F-2 diet. When the SHRSP were kept on the SP diet, all of the control SHRSP had cerebral apoplexy and severe hypertensive lesions in the heart and kidney. When betaxolol was chronically administered to SHRSP, cerebral apoplexy and hypertensive lesions in the heart and kidney were inhibited, but the effect on blood pressure was slight. Treatment with betaxolol reduced serum creatinine levels. Our observations show that betaxolol reduces blood pressure and potently inhibits hypertensive complications in SHRSP.
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PMID:[Antihypertensive effects of betaxolol, a cardioselective beta-adrenoceptor antagonist, in stroke-prone spontaneously hypertensive rats (SHRSP)]. 197 70

AHR-13268D (4-[3-[4-[Bis(4-fluorophenyl)hydroxymethyl]-1- piperidinyl]propoxy]benzoic acid, sodium salt) is a potent, long-acting water soluble, antiallergic and antihistaminic agent. AHR-13268D protects sensitive guinea pigs from collapse induced by aerosolized antigen; 1, 5, and 24 h ED50s in the test were 0.27, 0.25, 0.93 mg/kg, PO, respectively. AHR-13268D was also active when given as an aerosol, the 1 h ED50 = 0.29%. In the rat passivefoot anaphylaxis test. AHR-13268D was slightly more active (1.55 times) than AHR-5333B when given orally 1 h prior to challenge and equipotent to cromolyn when given intravenously immediately prior to challenge. AHR-13268D displayed potent, long-acting antihistaminic activity in naive guinea pigs; the 1, 5, and 24 h oral ED50s being in the range of 0.3 mg/kg. AHR-13268D (10 to 20 mg/kg, PO) attenuated the skin responses to ascaris antigen in sensitive dogs and did not alter the EEG pattern or sleep/wake patterns of cats at doses in vast excess of its antihistaminic activity. In vitro, AHR-13268D was a potent inhibitor of histamine release from rat peritoneal mast cells (IC50 = 0.51 nM) and was as potent as the reference 5-LO inhibitor phenidone in inhibiting antigen-induced contractions of guinea pig ileum in the presence of pyrilamine, atropine, and imidazole (IC50 approximately 300 microM). AHR-13268B was bioavailable (approximately 88%) from capsules or from oral solutions.
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PMID:The in vivo and in vitro activity of AHR-13268D, a new antiallergic/antihistaminic agent. 198 1

The potential of lipid monolayers spread at an air-water interface was investigated as a well defined membrane model able to support protein kinase C (PKC) association and activation. PKC association to a mixed phospholipid film (phosphatidylcholine, phosphatidylserine) could be detected by an increase of the monolayer surface pressure. This association was strikingly dependent upon the presence of submicromolar concentrations of Ca2+. The effect of Ca2+ resulted in an increase of the PKC penetration into the lipid core at a given permissive surface pressure as well as in a marked increase of the critical surface pressure (29-38 dynes/cm) above which the enzyme was excluded from the membrane. Inclusion of diacylglycerol or tetradecanoate phorbol acetate (TPA) did not modify the PKC-monolayer association in a detectable manner. PKC associated to the lipid layer exhibited the expected catalytic property and was fully activated when diacylglycerol or TPA was included in the membrane. PKC activity was highly dependent upon the surface pressure of the lipid monolayer, being optimal between 30 and 35 dynes/cm. Study of the compression isotherm of various diacylglycerol structures revealed that all potent PKC agonists exhibited an expanded liquid phase behavior with collapse pressure below 40 dynes/cm, in contrast to weak activators which showed condensed isotherms with high collapse pressure (approximately equal to 60 dynes/cm). These observations showed that the lipid monolayer system is well adapted to the study of the molecular mechanisms involved in the regulation of PKC activity at a model membrane interface. They are in line with the suggestion of a major role of Ca2+ in the association (translocation) of PKC to membrane in living cell and suggest that diacylglycerol (and TPA) might activate membrane-associated PKC through local change in the surrounding lipid phase organization.
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PMID:Activation of protein kinase C in lipid monolayers. 198 9

Transit of intestinal contents differs between the duodenum and ileum in intact animals. To determine whether this relates to intrinsic differences in the capacity, distensibility, or filling response of these segments, we used the isolated duodenum and ileum of 13 guinea pigs to record: (1) increases in the diameter and luminal volume produced by specific pressure heads and (2) the pressure waves and movements of the segments in response to bolus injections. We found that the duodenum and the ileum had similar diameters in the empty state, and when filled with volumes below 0.4 ml both generated baseline pressures below 3 cm H2O. However, the ileum increased its diameter and volume significantly more in response to increases in inflow pressure than the duodenum did. Conversely, injection of bolus volumes led to pressure waves of higher amplitude and longer duration in the duodenum than in the ileum. The pressure waves were produced by sharply defined ring contractions in the ileum; there was bulging of the walls downstream from the contraction site and collapse upstream from it. In the duodenum, the contraction involved a longer segment and was shallow with ill-defined margins. These intrinsic differences in the capacity, distensibility, and contraction patterns of the duodenum and ileum are likely to affect luminal transit and other mechanical functions of these intestinal segments in the intact animal.
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PMID:Intrinsic differences in the filling response of the guinea pig duodenum and ileum. 198 7

A V/Q lung scan was obtained in a patient with LLL collapse who was receiving IPPV and PEEP. This revealed absent ventilation and hyperperfusion to the collapsed lobe. After a reduction in PEEP from 12 to 5 cm H2O, a repeat V/Q scan showed a more even distribution of pulmonary perfusion. Arterial hypoxemia improved.
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PMID:PEEP and "reverse mismatch". A case where less PEEP is best. 154 Nov 83

The release of sodium and potassium and the uptake of sucrose molecules was studied in pig lenses incubated in isosmotic sucrose solution in either the presence or absence of 1% Triton X-100 (a non-ionic detergent). This Triton X-100 treatment has been shown to cause severe disruptions of cell membrane integrity. If sodium and potassium were free in the lens fibers as in a dilute aqueous solution, they would be expected to diffuse three to four times faster than sucrose. However, measurements of sodium and potassium release and sucrose uptake in the Triton X-100 treated lenses show a 1:1 equilibration. When pig lenses were incubated in the same solution without detergent, the sucrose uptake was significantly less than the potassium and sodium release. It is postulated that a slow, detergent mediated collapse of protein-water-ion interactions within the lens is the rate-limiting step of the observed equilibration of monovalent cations and sucrose molecules.
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PMID:Proportional equilibration of K, Na ions, and sucrose molecules in pig lenses incubated in the presence of the non-ionic detergent Triton X-100. 202 94

To evaluate the ability of two-dimensional echocardiographic indexes to determine the hemodynamic significance of the right ventricular infarction, 24 patients with electrocardiographic evidence of right ventricular infarction were studied. Hemodynamic significance was defined as a jugular venous pressure greater than 17 cm H2O or a right atrial pressure greater than 13 mm Hg. Patients with hemodynamically significant right ventricular infarctions (group I, n = 9) had a 56% incidence of hypotension (blood pressure less than 90 mm Hg) with a mean systolic blood pressure of 93 +/- 23 mm Hg, whereas patients with nonhemodynamically significant right ventricular infarctions (group II, n = 15) had no hypotension and a mean systolic blood pressure of 121 +/- 18 mm Hg (p less than 0.01). The ratio of right atrial to pulmonary capillary wedge pressure was 1.1 +/- 0.6 in group I and 0.6 +/- 0.2 in group II (p less than 0.05). Echocardiography demonstrated right ventricular free wall motion abnormalities in seven patients in group I and in 10 patients in group II. The descent of the right ventricular base was 0.7 +/- 0.2 cm in group I, 1.3 +/- 0.4 cm in group II, and 2.0 +/- 0.2 cm in a group of 20 normal control patients (p less than 0.001 for all comparisons). The respiratory caval index (percentage of collapse of the inferior vena cava with inspiration) was 22% +/- 11% in group I, 45% +/- 15% in group II, and 64% +/- 17% in the control subjects (p less than 0.05 for all comparisons).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Right ventricular infarction: recognition and assessment of its hemodynamic significance by two-dimensional echocardiography. 203 26

The amino terminus of subunit-2 of influenza virus hemagglutinin (NHA2) plays a crucial role in the induction of fusion between viral and endosomal membranes leading to the infection of a cell. Three synthetic analogs with an amino acid sequence corresponding to NHA2 of variant hemagglutinins were studied in a monolayer set up. Comparison of the interaction of a fusion-active and two fusion-defective analogs with a lipid monolayer revealed a greater surface activity of the fusion-active analog. Pronounced differences were found if the pure peptides were spread at the air/water interface; the fusion-active analog showed a higher collapse pressure and a greater limiting molecular area. Circular dichroism measurements on collected lipid monolayers indicated a high content of alpha-helical structure for the fusion-active and one of the fusion-defective analogs. A simple relation between alpha-helical content and fusogenicity does not seem to exist. Instead, the extent of penetration, a defined tertiary structure or orientation of the alpha-helical peptide may be essential for its membrane perturbing activity.
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PMID:The interaction of synthetic analogs of the N-terminal fusion sequence of influenza virus with a lipid monolayer. Comparison of fusion-active and fusion-defective analogs. 205 47

The comparative repeat dose toxicity of American cigarettes and kreteks (Indonesian cigarettes containing approximately 60% tobacco and 40% shredded clove buds) was assessed by exposure of groups of five male and five female rats to equivalent (approximately 2 mg/l in terms of total particulate matter) concentrations of smoke from each type of cigarette over 15 consecutive days. The smoke was delivered "nose only" using an HRC Rodent Smoking Machine (Mark IV). For each type of cigarette, three doses were used. These were achieved by regulating the daily total duration of exposure to smoke. The different doses used were 2 x, 4 x and 6 x, 15-min exposures, presented daily over a period of approximately 6 h. Inter-group comparisons were made between American and kretek groups which received the same daily durations of smoke exposure. Higher doses of smoke resulted in reduced bodyweight gains and food consumption in male groups; the response of female groups was not as clear. At the highest dose, male rats exposed to kretek smoke gained significantly more weight by comparison with males exposed to American smoke. Higher doses of smoke tended to increase water consumption in both sexes of groups exposed to American smoke; kretek smoke produced no obvious effect. Smoke exposures produced the expected responses in certain haematological and blood biochemical parameters attributed to exposure to CO and the irritants present in cigarette smoke. Such responses were, however, confined largely to the groups exposed to American smoke. Macroscopic pathological findings attributed to smoke inhalation were confined to the lungs, and consisted of minimal to moderate discolouration and incomplete collapse of the lung.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Comparison of the inhalation toxicity of kretek (clove cigarette) smoke with that of American cigarette smoke. II. Fourteen days, exposure. 207 25


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