Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Isolated rat hearts perfused with hyperosmotic Krebs-Henseleit buffer containing 60 mmol/L NaCl lose 10% of their tissue water. Perfusion of the rat hearts with Krebs-Henseleit buffer containing polyethylene glycol 8000 caused a concentration-dependent reduction in tissue water. In a study of the effect of different cryoprotectants on cardiac preservation, isolated rat hearts were flushed with a cardioplegic solution (CP-14), or CP-14 with either 50 mmol/L glycerol (CP-15), or 5% polyethylene glycol (CP-16) and frozen at -1.4 degrees C for 5 hours. Thawed hearts were reperfused in working mode to assess function. There was no recovery in CP-14 hearts. Hearts treated with CP-15 recovered 39.3% +/- 2.9% (mean +/- SEM) of control cardiac output. CP-16 boosted the recovery of cardiac output to 54.4% +/- 5.7% (p less than 0.05 vs CP-15). Glycerol significantly reduced tissue ice content; PEG further decreased the ice content to 31.7% +/- 0.6%, which was distinctively lower than that in CP-14 (44.7% +/- 1.1%) and in CP-15 hearts (34.6% +/- 1.1%). Tissue water content of CP-14 and CP-15 hearts was similar (3.83 and 3.87 gm H2O/gm dry weight). Polyethylene glycol reduced the tissue water content to 3.24 +/- 0.04 gm H2O/gm dry (p less than 0.01 vs CP-14 and CP-15 by ANOVA). Thus both glycerol and polyethylene glycol offered cryoprotection to the heart explant by reducing tissue ice formation. Polyethylene glycol was superior to glycerol by dehydrating myocardial tissue and further minimizing freezing damage.
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PMID:Freezing preservation of the mammalian heart explant. III. Tissue dehydration and cryoprotection by polyethylene glycol. 149 24

To explore the effect of serotonin (5-HT) on enteric electrical activity, transit and absorption, four dogs were prepared with 50 cm jejunal and ileal Vella loops. Electrodes for recording enteric electrical activity were attached to the loops and to the main small bowel. After recovery, both loops were perfused with a [14C-]PEG-glucose-electrolyte solution via the proximal stomas, while effluent was collected from the distal stomas and enteric electrical activity was monitored. Control periods were compared with periods when 5-HT was infused intravenously at a rate of 10 micrograms kg-1 min-1 for 60 min. Serotonin increased the mean +/- SEM % of jejunal and ileal pacesetter potentials with spike potentials from 33 +/- 7% and 35 +/- 9%, before infusion to 63 +/- 4% and 61 +/- 5% after infusion (P less than 0.05). Serotonin also induced distally-migrating bursts of spikes in the incontinuity small bowel. The changes were blocked by atropine, but not by ketanserin. Absorption of water, sodium and glucose from the jejunal and ileal loop and transit through the loops was not changed by 5-HT. At autopsy, all layers of the jejunum and ileum contained varicose nerve fibres with a positive immunoreaction to 5-HT, while positive nerve cell bodies were largely confined to the submucosa.
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PMID:Serotonergic regulation of canine enteric motility (measured as electrical activity) and absorption: physiologic and morphologic evidence. 322 19

A retrospective evaluation was carried out on the standard duodenal perfusion technique in human subjects. Polyethylene glycol (PEG 4000), non-labelled or labelled with 14C, and phenol red were used as duodenal and gastric recovery markers, respectively. The evaluation was limited to the 2-h equilibration period in each study. The studies were carried out on the subjects sitting in an armchair. Multi-perforated wide-bore aspiration tubes accompanied with air ventiles were used for duodenal and gastric aspiration. High perfusion flow rates (less than or equal to 13.5 ml min-1) and a long perfusion segment (15-20 cm) were applied in the duodenum and the collection periods were kept short. An efficient gastric and duodenal aspiration was obtained in most studies with a limited gastro-duodenal and duodeno-gastric flux. On average, the fluctuations in concentration of the duodenal marker (PEG 4000) ('steady state'), expressed as a coefficient of variation (CV), were 13.1 +/- 1.0% (SEM, n = 66). Correlation analysis suggested that the 'steady state' conditions in the duodenum were improved by an efficient gastric and duodenal aspiration and a high perfusion flow rate. This was supported by an inverse correlation found between the magnitude of the gastro-duodenal flux and the marker's fluctuations, the efficiency of the gastric aspiration and the magnitude of the gastro-duodenal flux, and the efficiency of the duodenal aspiration and the magnitude of the duodeno-gastric flux. A high correlation was found between the two duodenal perfusion markers used, PEG 4000 and 14C PEG 4000.
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PMID:An evaluation of a duodenal perfusion technique in human studies. 668 9

Gastrointestinal permeability has been assessed previously by the excretion of PEG-400, which consists of inert molecules that are neither degraded nor metabolized and are excreted intact in the urine. We report here the effects of alcohol on gastrointestinal permeability using PEG-400. Ten grams of PEG-400 dissolved in 60 ml of water were given to 12 intoxicated alcoholics (mean blood alcohol: 2406 mg/liter). The mean urinary excretion of PEG-400 in the following 6 hr was 3.75 +/- 0.3 g SEM. When repeated after sobering up (mean elapsed time: 45 hr), all except one subject showed a decrease in PEG-400 excretion (mean: 2.08 +/- 0.2 g) (P less than 0.001). Similar experiments were conducted in two series with 12 normal controls. (1) In 7 subjects the administration on consecutive days of (a) PEG-400 (10 g) alone, (b) 10.2 g (0.42 mol) of ethanol plus PEG-400 (10 g), (c) PEG-400 (10 g) alone, and (d) PEG-400 (10 g) plus a diuretic (40 mg furosemide) resulted in the following values of PEG-400 excretion in urine: (a) 2.12 +/- 0.3 g; (b) 3.5 +/- 0.3 g, P less than 0.005; (c) 2.02 +/- 0.4, NS; and (d) 2.2 +/- 0.2 g, NS. (2) In the second experiment (5 subjects) the administration on subsequent days of (a) PEG-400 (10 g) + 0.42 mol of urea; (b) PEG-400 (10 g) + 19.2 g ethanol; (c) PEG-400 (10 g) + 0.42 mol of urea resulted also, as in the previous experiment, in increased urinary excretion of PEG-400 after the solution (b) containing ethanol (P less than 0.001). Peak serum levels of PEG-400 were (a) 0.094 +/- 0.01 g/liter; (b) 0.152 +/- 0.02 g/liter (P less than 0.05); and (c) 0.095 +/- 0.01 (P less than 0.05). The ratio of urea--creatinine clearance and urinary volumes were the same in the three periods. Therefore, PEG-400 excretion was not related to changes in urinary clearance or in volume, since the furosemide increased the volume but not PEG-400 excretion. It is concluded that ethanol increases the permeability of the gastrointestinal tract as measured by the PEG-400 test, both in chronic alcoholics during intoxication and in nonalcoholics after a small dose of ethanol. The permeability alteration is transient once ethanol ingestion stops.
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PMID:Low-molecular-weight polyethylene glycol as a probe of gastrointestinal permeability after alcohol ingestion. 729 77

Production of oxygen-free radicals has been proposed as one pathophysiologic mechanism for postburn cardiac contractile dysfunction in adults. To examine this hypothesis in young subjects, we studied the cardiac effects of polyethylene glycol-superoxide dismutase (PEG-SOD) and PEG-catalase (PEG-CAT), each given as 20 U/g of body weight with fluid resuscitation (Parkland formula), after a third-degree burn constituting 33% of the total body surface area in young (6- to 7-day old) guinea pigs (group 3, n = 12). Fluid-treated burns without scavenger therapy (group 2, n = 15) and sham burn controls (group 1, n = 15) were included. Animals were killed 24 hours postburn, and hearts were studied in vitro (Langendorff). Compared with sham burn controls, fluid-treated burns (group 2) had significant cardiac dysfunction as indicated by a lower peak systolic left ventricular (LV) pressure (LVP: 67 +/- 2 vs. 57 +/- 4 mm Hg, p = 0.01, mean +/- SEM), maximal rate of LV pressure development (+dP/dt max: 1169 +/- 45 vs. 988 +/- 45 mm Hg/second, p = 0.01), and fall (-dP/dt max: 1109 +/- 45 vs. 919 +/- 49 mm Hg/second, p = 0.01). In addition, LV function curves calculated for group 2 were shifted downward and to the right of those calculated for sham burn controls in the direction of contractile depression, p = 0.01. PEG-SOD/PEG-CAT treatment in burns did not significantly improve LVP (60 +/- 5 mm Hg), but scavenger therapy improved +/-dP/dt max values (1112 +/- 74 and 988 +/- 98 mm Hg/second, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The role of toxic oxygen metabolites in a young model of thermal injury. 747 25

In vivo calcification of polyethylene glycol diacrylate (PEG DA) hydrogels of molecular weight (MW) 400, 1000, 4000, 6000 and 10,000 and polyethylene glycol tetraacrylate (PEG TA) of MW 18,500 was investigated using a rat subcutaneous model. This study was performed in 4-wk-old rats for durations of 1, 3, 6 and 8 wk. The results indicate a strong dependence of calcification upon the MW of the PEG precursor or the MW between crosslinks. Results for gels implanted for 6 wk show that calcification was maximal at a PEG MW of 1000 (224 mg/g +/- 12.8, n = 4) (mean +/- SEM) with less at MW = 400 (23.0 mg/g +/- 9.30, n = 4) and considerably less at higher MWs, e.g. for MW = 10,000 (0.23 mg/g +/- 0.01, n = 4). Results for other time periods indicate a similar calcification trend. The extent of calcification of gels from PEG TA (MW = 18,500) was intermediate (1.09 mg/g +/- 0.43, n = 3) between PEG DA (MW = 6000) (1.39 mg/g +/- 0.42, n = 6) and PEG DA (MW = 10,000) at 6 wk, i.e. calcification depended upon the PEG MW between crosslinks. When composite gels were implanted, such that a highly calcifying gel (MW = 400 or 1000) was encapsulated within a gel of low calcification (MW = 4000), the gel inside calcified to at least the same extent as if it had not been encapsulated. Thus, direct contact with tissues is apparently not necessary for calcification to occur. Energy dispersive X-ray spectroscopy was performed on the mineral deposits in the gels and a P:Ca ratio of 0.67 +/- 0.04 (95% confidence interval) for MW 1000 gels and 0.60 +/- 0.07 for MW 400 gels was found to be consistent with deposition of Ca3(PO4)2.
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PMID:Molecular weight dependence of calcification of polyethylene glycol hydrogels. 783 41

This study assessed the effect of profound inhibition of gastric secretion by an H2 antagonist on postprandial gastric emptying of acid and chyme, and on bile acid and pancreatic enzyme secretion under physiological conditions in humans. Six subjects were studied before and while they were given famotidine (40 mg). This study combined a continuous intestinal perfusion technique using 14C-polyethylene glycol (14C-PEG) as duodenal recovery marker, with intermittent sampling of gastric content using PEG 4000 as meal marker. During the three hour study, the area under the curve for gastric acid output decreased from mean (SEM) 88.9 (7.6) mmol for those not receiving treatment, to 21.2 (2.7) mmol for subjects receiving famotidine (p < 0.01). The corresponding values for the rate of acid delivery into the duodenum decreased from 65.2 (11.9) to 16.6 (2.9) mmol (p < 0.05), and those for the rate of gastric emptying of chyme remained unchanged for the group receiving no treatment and during famotidine (1040 (200) v 985 (160) ml respectively, NS). Duodenal bile acid and trypsin output remained unchanged (area under the curve, 457 (128) v 373 (86) umol/kg and 5022 (565) v 5058 (400) IU/kg respectively, NS) receiving no treatment and during famotidine. It is concluded that profound inhibition of postprandial gastric acid secretion by anti-secretory drugs is not accompanied by changes in biliary and pancreatic secretion, mainly because the gastric emptying of chyme is unaffected.
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PMID:Postprandial biliary and pancreatic secretion during profound inhibition of gastric secretion in humans. 824 51

Poly(DL-lactic acid), synthesized in this laboratory from DL-lactic acid, was used to prepare microspheres containing piroxicam, using a solvent evaporation technique. The microspheres obtained were characterized for their surface characteristics (by SEM), surface charge, density, particle size distribution, glass transition temperature, drug incorporation and encapsulation efficiency, IR spectroscopy and in vitro drug release. The suspension of microspheres was evaluated for its syringeability. The effect of channelling agents such as PVP and PEG 6000 on in vitro drug release was studied. The effect of gamma-radiation on poly(DL-lactic acid) and on the in vitro release of piroxicam from the microspheres was also studied.
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PMID:Biodegradable microspheres of poly(DL-lactic acid) containing piroxicam as a model drug for controlled release via the parenteral route. 826 74

Knowledge of bovine oocyte plasma membrane permeability characteristics at different developmental stages in the presence of cryoprotective agents (CPAs) is limited. The objective of this study was to determine the oolema hydraulic conductivity (Lp), cryoprotectant permeability (P[CPA]), and reflection coefficient (sigma) for immature (germinal vesicle stage, GV) and in vitro-matured (metaphase II, MII) bovine oocytes. Two commonly used cryoprotective agents, dimethyl sulfoxide (DMSO) and ethylene glycol (EG), were studied. Osmometric studies were performed using a micromanipulator connected to an inverted microscope at 22 +/- 2 degrees C. Each oocyte was immobilized via a holding pipette, and osmotically induced volume changes over time (dv/dt) were recorded. The Lp values for GV and MII oocytes in DMSO (L(p)DMSO) were 0.70 +/- 0.06 and 1.14 +/- 0.07 microm/min/atm (mean +/- SEM) and in EG (L(p)EG) were 0.50 +/- 0.06 and 0.83 +/- 0.07 microm/min/atm, respectively. Estimates of P(DMSO) for GV and MII oocytes were 0.36 +/- 0.03 and 0.48 +/- 0.03 microm/sec, and PEG values for GV and MII oocytes were 0.22 +/- 0.03, 0.37 +/- 0.03 microm/sec, respectively. The values for GV and MII oocytes in DMSO (sigma[DMSO]) were 0.86 +/- 0.03 and 0.90 +/- 0.04 and in EG (sigma[EG]) were 0.94 +/- 0.03 and 0.76 +/- 0.04, respectively. These data demonstrate that bovine oolema permeability coefficients to water and cryoprotectants change after in vitro maturation. Furthermore, the bovine oocyte P(DMSO) is higher than the P(EG). These results may provide a biophysical basis for developing criteria for choosing optimal CPAs and for minimizing damage during addition and removal of the CPAs. Additionally, these data support the hypothesis that different procedures may be required for optimal cryopreservation of different oocyte developmental stages.
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PMID:Effect of developmental stage on bovine oocyte plasma membrane water and cryoprotectant permeability characteristics. 950 92

A swellable matrix tablet is described which is partially coated with cellulose acetate (CA) to obtain a film having the shape of a cup, whose permeability to water and solutes was altered by mixing increasing amounts of poly(ethylene glycol) 400 (PEG). The drug-release mechanism from such systems was assessed by carrying out drug-release experiments both in water and saline solutions. Drug permeability through the polymeric cup and SEM analysis on the films were also performed. It was found that the systems exhibited drug-release kinetics very close to linearity. The mechanisms governing drug release were (i) drug diffusion through the uncoated gel layer, (ii) drug transport through the gel layer due to the osmotic pressure difference, and (iii) drug diffusion through the cup pores. The relative importance of each contribution depended on the amount of PEG in the film. The systems with a cup containing 1%, 13%, and 33% PEG w/w behaved in part as osmotic systems, whereas the system having a permeable cup behaved as a hybrid reservoir system. These modifications of the coating permeability introduce a further possibility of modulating drug-release kinetics and lead to a reduced dependence of swellable matrix tablet release on environmental conditions.
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PMID:Partial permselective coating adds an osmotic contribution to drug release from swellable matrixes. 960 50


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