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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of five perfusion flow rates (4,5, 9, 12, 30 and 60 ml/h) on the intestinal absorption of glucose, fructose and sucrose were studied in the rat with a "temporary" Thiry-Vella loop (jejunum = 20 cm). Sucrose hydrolysis and intestinal transport of actively and passively absorbed solutes were markedly affected when the flow rates rose to a value higher than the limiting rate of 12 ml/h. With a flow rate up to 60 ml/h, glucose and fructose were absorbed at the same rate, but this was not due to thinning of the unstirred water layer. Sucrose hydrolysis was likewise completely inhibited. This result cannot be attributed to a product inhibition because of the absence of hexoses in the exit perfusate. These observations had important implications in the comparison of the intestinal absorption of many nutrients to evaluate the optimal perfusion rate corresponding to intestinal function integrity.
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PMID:[Effects of perfusion flow rates on the intestinal absorption of carbohydrates]. 734 88

We studied the depletion of the post-lens tear film as contributing to inferior arcuate staining with ultrathin high water content hydrogel lenses. We monitored the post-lens tear film specular reflection of hydrogel lenses (0.04 mm center thickness, 67% nominal water content), which caused inferior arcuate staining. A standard thickness (0.12 mm) lens was worn in the contralateral eye as a control condition. Lenses were worn for a 2 hour period by 20 subjects. Post-lens tear film appearances were categorized as amorphous, faint colored, or colored, where the colored patterns represented a relatively depleted post-lens tear film. We also measured lens dehydration, lens adherence, and pre-lens tear film stability in order to evaluate their role in inferior arcuate staining. The ultrathin and standard lenses caused staining in 100 and 75% of subjects, respectively; the severity of staining was much greater with the ultrathin lenses (Wilcoxon signed ranks test, P = 0.0004). The ultrathin lenses were associated with a higher incidence of post-lens tear film depletion (P = 0.018), had greater front surface dehydration (P = 0.0004), and were more adherent to the eye (paired t-test, P = 0.001). However, pre-lens tear thinning times were not significantly different between the two lens types (Wilcoxon signed ranks test, P > 0.05). These findings support the contention that post-lens tear film depletion is a component of a lens adherence or lens dehydration mediated mechanism of inferior arcuate staining.
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PMID:Role of the post-lens tear film in the mechanism of inferior arcuate staining with ultrathin hydrogel lenses. 758 76

The determinants of postlens tear film (PTF) composition in hydrogel lens wear are poorly understood, although this layer has important roles in lens movement and corneal integrity. We investigated the hypothesis that the PTF could be depleted by instillation of hypotonic saline, using a randomized, double masked, placebo controlled study design. Solutions of 0.90, 0.60 and 0.45% NaCl were instilled into the eyes of 12 subjects wearing ionic and non-ionic high water content hydrogel lenses. Postlens tear film appearances in specular reflection were categorized as amorphous, faint coloured or coloured, where the coloured patterns represent a progressive thinning of the PTF. With instillation of the hypotonic solutions (0.60 and 0.45% NaCl), the appearance of the PTF in specular reflection changed to a faint coloured or coloured pattern in at least 67% of subjects for each lens type (Friedman ANOVA, P < 0.002). For the 0.45% NaCl solution, median lens movement decreased from 0.50 to 0.10 mm (Friedman ANOVA, P = 0.02); however, there were no significant changes in measured lens parameters and no difference between lens types. Postlens tear film depletion due to a hypotonic shift in tear osmolality, as demonstrated here, may explain the clinically observed phenomenon of lens binding.
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PMID:Osmotic determinants of postlens tear film morphology and hydrogel lens movement. 765 7

Silicone-fluorosilicone copolymer oil is characterized by being heavier than water (density, 1.16 g cm-3) and low viscosity (175-185 centistokes) compared with currently used intraocular silicone oils (density, 0.97 g cm-3 and 1000-5000 centistokes). This oil is potentially useful as an operative tool and a tamponade on the inferior retina in complicated retinal detachment. We evaluate the ocular response clinically and histopathologically within 8 weeks in rabbit phakic eyes to the purified silicone-fluorosilicone copolymer oil after vitreous cavity injection, and compared the oil tolerance with purified silicone oil (0.97 g cm-3, 5000 centistokes) and perfluorotetradecahydrophenanthrene for ophthalmic use (Vitreon, 2.03 g cm-3, 8.03 centistokes) which are currently used as operative tools and as internal retinal tamponade agents in retinal detachment surgery. Because of their low viscosity, silicone-fluorosilicone copolymer oil and perfluorotetradecahydrophenanthrene were easier to inject into the eye than silicone oil. Silicone-fluorosilicone copolymer oil and perfluorotetradecahydrophenanthrene occupied the inferior portion in the eye, and silicone oil occupied the superior portion. Fewer discrete oil droplets and weaker vessel attenuation of medullary rays than in the perfluorotetradecahydrophenanthrene-injected eyes were seen in silicone-fluorosilicone-copolymer-oil-injected eyes. Histopathologically, all retinas injected with silicone-fluorosilicone copolymer oil were normal within 4 weeks. The silicone-fluorosilicone copolymer oil dispersion did not induce histopathological changes within 8 weeks. However, thinning or disappearance of the outer plexiform layer was seen in the inferior retina in some silicone-fluorosilicone-copolymer-oil-injected eyes at 6-8 weeks. A similar effect was found in the superior retina of a silicone-oil-injected eye at 8 weeks. More severe changes such as thinning or disappearance of the outerplexiform layer, thinning and disorganization of the photoreceptor layer, and migration of the receptor cell nuclei to the photoreceptor layer were found in the inferior retina of perfluorotetradecahydrophenanthrene-injected eyes after 2 weeks. Intraocular silicone-fluorosilicone copolymer oil tolerance until about 2 months post-injection is similar to silicone oil and better than perfluorotetradecahydrophenanthrene. Silicone-fluorosilicone copolymer oil may be useful intraoperatively and as a temporary vitreous substitute in cases of inferior retinal detachment.
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PMID:Histopathology of rabbit eyes with intravitreous silicone-fluorosilicone copolymer oil. 769 67

The viscoelastic properties of poly(ethylene oxide) (PEO) solution were investigated using the dynamic oscillatory testing technique. With this technique, the effect of PEO molecular weight (MW), concentration, composition of mixed solvent systems consisting of propylene glycol, glycerol formal, and water, and the effect of NaCl salt on the viscoelastic properties of PEO solution were determined. Dynamic moduli (G1, G2), magnitude of complex viscosity (magnitude of eta*), and loss tangent (tan delta) were examined over a frequency range of 10(-3)-2.5 Hz at 30 degrees C. The results indicated that low MW PEOs show liquidlike behavior while high elasticity is exhibited by high MW PEOs due to entanglement formation. The complex viscosity, magnitude of eta*, exhibits shear thinning (power-law) characteristics under oscillatory measurements. The relationship between steady shear and complex viscosities follows the Cox-Merz rule over the shear rate and frequency region studied. Both the storage (G1) and loss (G2) modulus increase drastically as the proportion of water in the mixed solvent system increases. Similarly, both G1 and G2 are found to increase while the tan delta decreases with increasing concentration of PEOs. The addition of up to 2% w/w NaCl in an aqueous solution of 10% w/w 2 million MW PEO has no observed detrimental effect on the viscoelastic behavior.
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PMID:Viscoelastic properties of poly(ethylene oxide) solution. 788 67

We describe an experimental study in which morphometric techniques are used to question traditional conceptions about the behavior of the alveolus under changes in pressure. An increase in inflation pressure in the lung results in alveolar recruitment (an increase in distal air spaces) due to stretching of its walls. To test this hypothesis, the lungs of rats were filled to 25 to 35 cm water pressure. Lungs filled to a higher pressure were expected to present a decrease in alveolar size along with thinning of its walls, and an increase of internal perimeter of the alveolus with no change in amount of tissue. Morphometric data were processed by computer and results were analyzed by statistical tests. The lungs of 10 Wistar rats were examined under light microscope. The following variables were recorded: mean linear intersection (Lm), alveolar cord, wall thickness, internal alveolar perimeter and tissue percentage. Lower Lm in lungs filled to 35 cm water pressure allows us to consider that the number of alveoli increased; lower Lm and alveolar cord indicate that alveolar size is smaller; alveolar wall thickness decreased; internal alveolar perimeter increased. All these differences were statistically significant (p < 0.001), tissue percentage being the only variable that did not change significantly. All results lead us to consider that an increase in lung inflation pressure leads to alveolar recruitment and stretching of its walls.
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PMID:[Alveolar recruitment under high-pressure transpulmonary inflation. An experimental morphometric study]. 802 87

We assessed the therapeutic efficacy of a low-dose combination of metoprolol and captopril given orally to C3H/Hej mice that developed dilated and hypertrophied hearts after being inoculated with the encephalomyocarditis virus. Mice were randomly assigned to one of six 8-week oral regimens: 1 mg/kg/day of metoprolol (group 1); 10 mg/kg/day of metoprolol (group 2); 1.2 mg/kg/day of captopril (group 3); 12 mg/kg/day of captopril (group 4); 1 mg/kg/day of metoprolol plus 1.2 mg/kg/day of captopril (group 5); or distilled water (control group). Group 4 exhibited a significantly lower survival rate and body weight than the control group (p < 0.01). Survival rates and body weights were similar in groups 1, 2, 3, 5, and the control group. Low-dose metoprolol plus captopril is superior to low-dose metoprolol, high-dose metoprolol, and low-dose captopril with regard to heart weight and the heart weight/body weight ratio. The left and right ventricular cavity dimensions as well as myocardial necrosis, calcification, and fibrosis were less severe in groups 4 and 5 than in the control group. The left ventricular free wall showed significantly more thinning in group 4 than in the control group (p < 0.01). Our results show that the administration of low-doses of metoprolol and captopril given in combination was effective in this animal model of congestive heart failure and was associated with a reduction in biventricular cavity dimensions and myocardial necrosis.
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PMID:Low-dose combination therapy with metoprolol and captopril for congestive heart failure in mice. 811 Jun 23

The effects of calcium deficient diet and acetazolamide on the gas exchange characteristics of avian eggshells were independently investigated in two groups of unmated hens (Gallus domesticus). In one group, eggs were collected during both a normal diet (3.00% Ca) and a calcium deficient diet (0.34% Ca). In another group, eggs were collected both before and after acetazolamide administration (200 mg/kg) per os. Eggshell water vapor conductance (GH2O) increased 30% during the calcium deficient diet and was accompanied by a 21% decrease in eggshell thickness (L). Eggshell GH2O increased 200% one day after acetazolamide administration and was not only accompanied by a 36% decrease in L, but also by an 89% increase in total functional pore area (Ap). We conclude that a calcium deficient diet increases GH2O by eggshell thinning with little effect on Ap. On the other hand, acetazolamide profoundly increases GH2O, not only by eggshell thinning but also by a remarkable increase in Ap.
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PMID:Calcium deficient diet, acetazolamide and gas exchange characteristics of avian eggshells. 815 50

Reperfusion that is too late to salvage ischemic myocardium reduces early infarct expansion, and captopril therapy favorably alters long-term left ventricular remodeling. To study whether the beneficial effects of these two therapies are additive, we examined the effects of captopril therapy after late reperfusion on left ventricular remodeling after acute myocardial infarction. Female Sprague-Dawley rats (n = 67) were randomly assigned to one of four groups: group 1, sham surgery and no treatment; group 2, left coronary artery ligation and no treatment (myocardial infarction [r MI]); group 3, left coronary artery ligation, reperfusion 2 hours later, and no treatment (late reperfusion [LR]); and group 4, left coronary artery ligation, reperfusion 2 hours later, and captopril treatment (LR-Cap). Captopril therapy (2 gm/L of drinking water) was begun in the LR-Cap group in the immediate post-operative period and continued for 20 days. Twenty-one days postoperatively, hemodynamic measurements were made before and after volume loading. The rats were killed, their hearts were removed, and passive pressure-volume curves were obtained. The hearts were then fixed at a constant pressure for morphometric analysis. Compared with the MI group, the LR group had a lower expansion index and a higher thinning ratio. There were no differences in hemodynamics, left ventricular volumes, or other morphometric indexes between the two groups. Compared with the MI and LR groups, the LR-Cap group had lower peak left ventricular end-diastolic pressure, lower left ventricular volume, lower left and right ventricular weights, and a leftward shift of pressure-volume curves.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of captopril therapy after late reperfusion on left ventricular remodeling after experimental myocardial infarction. 815 12

The effects of metoprolol on early infarct expansion after acute myocardial infarction were studied in rats (n = 54) that underwent either left coronary artery ligation (MI) or sham operation. Immediately after surgery, the rats received either metoprolol (M) by mouth, which had been dissolved in drinking water, for 72 hours supplemented with three intraperitoneal doses over the first 24 hours or no treatment (H2O). Three days after the initial surgery, hemodynamic measurements were made before and after volume loading. The rats were killed, the hearts were removed, and passive pressure-volume curves were obtained. The hearts were then fixed at a constant pressure and analyzed morphometrically. Infarct size was nonsignificantly lower in the metoprolol-treated group compared with the untreated group (38% +/- 5% MI-M vs 48% +/- 3% MI-H2O, p = 0.10) Compared with infarcted untreated rats, infarcted metoprolol-treated rats had a lower heart rate (322 +/- 13 beats/min MI-M vs 452 +/- 19 beats/min MI-H2O, p < 0.001), lower left ventricular systolic pressure (63 +/- 4 mm Hg MI-M vs 90 +/- 6 mm Hg MI-H2O, p = 0.004), and lower +dp/dt (1340 +/- 169 mm Hg/sec MI-M vs 2872 +/- 273 mm Hg/sec MI-H2O, p < 0.001), but left ventricular end-diastolic pressure and cardiac index did not differ between the two groups. Left ventricular weight corrected for body weight was higher in infarcted rats treated with metoprolol compared with infarcted untreated rats (2.76 +/- 0.07 gm/kg MI-M vs 2.41 +/- 0.09 gm/kg MI-H2O, p < 0.05). The initial slope of the pressure-volume relationship Ki, an index of operative volume stiffness, was lower in infarcted rats treated with metoprolol compared with infarcted untreated rats (p = 0.03). There were, however, no significant differences in the expansion index, thinning ratio, or left ventricular volume between the two infarcted groups. Thus metoprolol therapy begun in the immediate postinfarction period promotes an increase in left ventricular weight and reduces operative volume stiffness but has no significant effect on indexes of early infarct expansion.
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PMID:Effects of metoprolol on early infarct expansion after acute myocardial infarction. 815 13


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