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)

The quantification of adenine nucleotides released from the heart is hampered by their rapid dephosphorylation to adenosine in the extracellular space catalyzed by highly active ectonucleotidases. To determine the total release of adenine nucleotides from isolated Langendorff-perfused guinea pig hearts, ecto 5'-nucleotidase was effectively blocked by infusion of alpha, beta-methylene-ADP (AOPCP, 50 microM). Adenine nucleotides were measured in the coronary venous effluent by the luciferin-luciferase method after enzymatic rephosphorylation to ATP. In hearts perfused at a constant flow rate (10 ml/min) with normoxic buffer (95% O2, 5% CO2) the release +/- SEM of adenine nucleotides and adenosine was 0.06 +/- 0.01 (n = 11) and 0.04 +/- 0.01 (n = 13) nmol/min. In the presence of AOPCP, the release of adenine nucleotides increased to 0.43 +/- 0.04 nmol/min (n = 9; p less than 0.05), whereas adenosine remained unchanged. Hypoxic perfusion (10% O2, 85% N2, 5% CO2) caused a threefold increase in adenine nucleotide release but a 40-fold increase in adenosine. In contrast, global ischemia (30 seconds) caused adenine nucleotide and adenosine release to rise to similar values of 1.06 +/- 0.10 and 0.80 +/- 0.14 nmol/min (n = 9). Stimulation of hearts with isoproterenol (4 nM) likewise increased the release of adenine nucleotides (0.50 +/- 0.04 nmol/min) and adenosine (0.87 +/- 0.21 nmol/min) (n = 6). To determine the cellular source of adenine nucleotides released from the heart, the coronary endothelial adenine nucleotide pool was selectively prelabeled by [3H]adenosine. Global ischemia increased the specific radioactivity of released adenine nucleotides by 57%. The findings indicate that 1) adenine nucleotides and adenosine are released at the same order of magnitude from the well-oxygenated heart; 2) beta-adrenergic stimulation and ischemia stimulate the release of adenine nucleotides and adenosine, both purines reaching vasoactive concentrations in the effluent perfusate; 3) during hypoxic perfusion only the release of adenosine is greatly enhanced; and 4) the coronary endothelium preferentially contributes to the ischemia-induced adenine nucleotide release.
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PMID:Adenine nucleotide release from isolated perfused guinea pig hearts and extracellular formation of adenosine. 174 67

The purpose of this study was to determine the effect of fitness and work level on the O2 uptake and CO2 output kinetics when the increase in work rate step is adjusted to the subject's maximum work capacity. Nine normal male subjects performed progressive incremental cycle ergometer exercise tests in 3-min steps to their maximum tolerance. The work rate step size was selected so that the symptom-limited maximum work rate would be reached in four steps at 12 min in all subjects. Oxygen consumption (VO2) and carbon dioxide production (VCO2) were calculated breath by breath. For the group, the time (mean, SEM) to reach 75% of the 3-min response (T0.75) for VO2 increased significantly (P less than 0.01) at progressively higher work rate steps, being 53.3 (5.5) s, 63.5 (4.6) s, 79.5 (5.0) s, and 94.5 (5.8) s, respectively. In contrast, T0.75 for VCO2 did not change significantly [74.9 (7.4) s, 75.6 (5.0) s, 85.1 (5.3) s, and 89.4 (6.3) s, respectively]. VCO2 kinetics were slower than VO2 kinetics at the low fractions of the subjects' work capacities but were the same or faster at the high fractions because of the slowing of VO2 kinetics. The first step showed the fastest rise in VO2. While VO2 kinetics slowed at each step, they were faster at each fraction of the work capacity in the fitter subjects. The step pattern in VO2 disappeared at high work rates for the less fit subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The role of fitness on VO2 and VCO2 kinetics in response to proportional step increases in work rate. 174 11

Extracted third molars were used to study the effect of Nd:YAG laser irradiation combined with CO2 laser beam on dental hard tissues. The specimens were studied with SEM after lasing and the size of the impact areas and beam penetration into enamel and dentin were planimetrically analyzed. High-energy CO2 laser (e.g. 10 s irradiation with 10 W output energy) penetrated all enamel and dentin. The simultaneous addition of Nd:YAG irradiation to the CO2 beam was found to increase the effect of CO2 laser, while Nd:YAG irradiation alone, used with equivalent energy densities, did not cause any effect on enamel surface. Thus, Nd:YAG laser was found to potentiate statistically significantly the effect of CO2 irradiation, but the morphologic alterations on dental hard tissues, such as crater formation at the beam focus site, appeared to be due to CO2 irradiation alone.
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PMID:Irradiation of human dental tissues with CO2-, Nd:YAG-, and CO2-Nd:YAG combination laser. 176 82

In contrast to the high standard of intraocular lens implantation today, lens fixation and the occurrence of secondary opacifications are still not satisfactory. We are working on an implant that builds a stable connection to the surrounding lens-capsule. Disc-shaped lenses made of poly(dimethylsiloxane) were treated with different kinds of plasma to bring functional groups to the surface. This allows further macromolecular coating. The results of the surface modifications were characterized by electron spectroscopy for chemical analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and cell culture experiments. O2 plasma induces a rapid increase of functional groups on the lens surface. CO2 plasma has to be used for longer treatment periods to achieve the same increase, but as SEM shows, did not lead to surface damage up to periods of 300 s. Using O2 plasma for longer than 60 s, a crack formation occurred. Therefore, CO2 plasma may be a more effective and sensitive tool in grafting functional groups to the surface.
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PMID:Plasma-induced surface modifications on silicone intraocular lenses: chemical analysis and in vitro characterization. 189 89

The dependence between maximum net ultrafiltration rate (nUFR) created by 15% dextrose dialysis solution and effective peritoneal capillary blood flow (EPBF) estimated by the diffusive mass transport coefficient (KBD) and peritoneal clearance (Cp) of CO2 gas was evaluated during 30 minute, 15 ml peritoneal dialysis exchanges in anesthetized rats (N = 18). The values of KBD for CO2 suggested a mean EPBF of 1.9 +/- 0.1 (SEM) ml/min for isosmotic exchanges and 2.7 +/- 0.2 ml/min for hyperosmotic ones with a mean maximum nUFR of 0.43 +/- 0.01 ml/min. Cp of CO2 measured after the first five minutes of dwell underestimated EPBF. In normally hydrated rats, maximum nUFR was achieved when the peritoneal filtration fraction was 32 +/- 2%. This value is similar to the glomerular filtration fraction in rats of 30%. Thus, our results indicate the following relationships: EPBF = (approximately 3 x maximum nUFR)/(1 - hematocrit). EPBF was about six times greater than maximum nUFR and exceeded about 57 times nUFR obtained under isosmotic conditions. These differences between EPBF and nUFR suggest normal EPBF is not a major limiting factor for maximum ultrafiltration achieved during peritoneal dialysis.
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PMID:Ultrafiltration and effective peritoneal blood flow during peritoneal dialysis in the rat. 190 62

Gingival crevice and periodontal pocket pH, measured directly with glass micro-electrodes, was near neutral at most sites in most individuals (mean pH 6.92 +/- 0.03 SEM, 69 subjects). Periodontal state ranged from healthy to periodontitis but neither clinical evidence of gingivitis at a site nor pocket depth were associated with crevicular pH different from that at healthy sites. This finding contradicts earlier reports that gingivitis is associated with a crevicular pH as alkaline as pH 9.06. Metallic antimony electrodes as used by earlier investigators were found to give pH readings that were too high by as much as 1.5 pH units in the presence of organic reducing agents of the type produced by oral bacteria within gingival crevices. In contrast, glass micro-electrodes respond only to hydrogen ions and thereby provided accurate measurements of pH even in the presence of organic reducing agents. Loss of CO2 to the atmosphere from biological fluids that are bicarbonate buffered resulted in a shift to alkaline pH by as much as 1 pH unit. As a result, only measurements taken within gingival crevices or periodontal pockets can provide accurate measurements of crevice or pocket pH.
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PMID:The pH of gingival crevices and periodontal pockets in children, teenagers and adults. 190 71

The treatment of burn patients with recombinantly derived human growth hormone (rHGH) appears effective in counteracting protein catabolism. However, exogenous growth hormone is frequently associated with hyperglycemia, an aspect which may limit its usefulness. Therefore, to assess the affect of rHGH on glucose utilization, 13 severely burned patients (65% +/- 4 TBSA burn; mean +/- SEM) began receiving on admission either placebo or rHGH (0.2 mg/kg.d) in a double-blind randomized fashion. While hypermetabolic (percentage REE/predicted REE 1.41 +/- 0.11) fasting oxygen consumption and CO2 production were measured using indirect calorimetry prior to and then during a hyperinsulinemic euglycemic clamp. This experiment demonstrated that rHGH significantly reduced glucose uptake and inhibited glucose oxidation compared to the placebo patients. Since the decreases in glucose oxidation and uptake were proportional, glucose utilization (percentage glucose uptake oxidized) remained similar in both patient groups. Furthermore, the hyperinsulinemic clamp lowered the plasma amino acid concentrations in the control patients while rHGH-treated patients had no significant alterations. In conclusion, exogenous growth hormone therapy induces an insulin resistance in burn patients. Furthermore, since the glucose utilization did not change, it is likely that the mechanism of insulin resistance is due to a deficiency in glucose transport.
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PMID:Effect of exogenous growth hormone on glucose utilization in burn patients. 194 90

The authors sought to determine how hypoperfusion influences acid-base balance in arterial and mixed venous blood. In anesthetized, ventilated pigs (n = 12), we determined hemodynamics, O2 uptake, CO2 output, dead-space ventilation, arterial and mixed venous blood acid-base balances, and lactate concentrations during graded reductions in cardiac output by incremental positive end-expiratory pressure (PEEP, 0-20 cm H2O). Cardiac output decreased from 3.2 +/- 0.2 (mean +/- SEM) to 1.2 +/- 0.1 L/min at 20 cm H2O PEEP. Oxygen delivery declined more than O2 uptake did by 60% +/- 2% and 27% +/- 2%, respectively. The decrease in CO2 output (by 21% +/- 2%) was less than that in O2 uptake. Fractional dead-space ventilation increased. At a slight increase in carbon dioxide tension (PCO2) of 4 +/- 1 mm Hg, pH decreased in arterial blood from 7.54 +/- 0.01 to 7.47 +/- 0.02 mmol/L, and standard bicarbonate decreased from 30.3 +/- 0.5 to 27.5 +/- 0.6 mmol/L. The decrease in standard bicarbonate exceeded the increase in blood lactate concentrations. At a similar decrease in standard bicarbonate, the decrease in pH was larger (P less than 0.005) in mixed venous blood than in arterial blood owing to a larger increase in PCO2 (from 40 +/- 2 to 50 +/- 2 mm Hg, P less than 0.005). The changes were reversed after discontinuing PEEP. The authors conclude that ischemia after incremental PEEP results in tissue metabolic acidosis with superimposed respiratory acidosis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Arterial and mixed venous blood acid-base balance during hypoperfusion with incremental positive end-expiratory pressure in the pig. 195 38

A retrospective study to determine the relationship between early microporous membrane oxygenator (MMO) failure and blood pressure at the MMO outlet (Pmo) was conducted using data collected with 19 dogs (22 +/- 1 kg, mean +/- SEM) undergoing routine normothermic cardiopulmonary bypass. Because gas flow was maintained at a high level, it could not be used to control CO2 exchange. Instead, blood PCO2 was controlled by adding CO2 to the sweep gas. Blood PO2 was controlled as suggested by the manufacturer, by adjusting the %O2 in the gas phase (g). Blood flow was 2575 +/- 54 ml/min; Pmo ranged from 173 to 790 mm Hg; and hematocrit was 33 +/- 1%. O2 exchange was calculated from blood gas parameters. Changes in the diffusion potential of O2 (delta PO2) and CO2 (delta PCO2) and MMO performance (P, taken as oxygen exchange normalized to a diffusion potential of 100 mm Hg) indicated MMO failure. Initial values, taken within 60 min of bypass initiation, were compared to final values taken at 226 +/- 9 min of bypass. Despite higher final delta PO2 (411 +/- 9 vs. 538 +/- 19 mm Hg, p less than 0.0001 paired t-test) and delta PCO2 (18.6 +/- 2.4 vs. 30.5 +/- 4.7 mm Hg, p less than 0.0017), arterial blood PO2 decreased (159 +/- 15 to 89 +/- 6 mm Hg, p less than 0.0005) and PCO2 increased (36.4 +/- 1.5 to 46.1 +/- 3.0 mm Hg, p less than 0.0039), and the performance decreased [24.5 +/- 1.1 to 20.1 +/- 0.7 (ml/min)/(100 mm Hg), p less than 0.0001].(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The effect of high pressure on microporous membrane oxygenator failure. 199 86

This study was designed to investigate the effects of CO2 laser irradiation on the dentin microstructure, dentin adhesion of resin composites and dental pulp. An artificial caries lesion was produced on the bovine dentin, immersing in 0.4 mol/l acetic acid. Three kinds of dentin (sound dentin, outer or inner caries dentin) surfaces were pretreated by the laser irradiation, acid etching or no-treatment. The tensile adhesion-test of these pretreated dentin surfaces was performed. The changes in these dentin surfaces by the various treatments including the laser irradiation and the resin-dentin interfaces were examined by the SEM. Furthermore, histopathological study using monkey teeth was conducted to examine the effect of the laser irradiation on the dental pulp. Histopathological changes in the pulp were found at 3 and 90 days after the operation. The findings were as follows: 1. The outer highly and inner partially decalcified layers produced in the bovine dentin were each approximately 200 microns in thickness. 2. The bond strength of the resin composites to the laser pretreated sound dentin was approximately 40 kgf/cm2. Those of the laser pretreated outer and inner decalcified dentins were about 60 kgf/cm2. 3. At the initial stage, the laser irradiation (output power 3W : irradiation period 0.5 second) exhibited a slight pulpal response, producing irritation dentin formation in the latter stage without any severe histopathological change.
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PMID:[Effects of CO2 laser irradiation on microstructure of dentin, dentin adhesion of resin composites and dental pulp]. 206 31


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