Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Isolated rat heart preparations were studied to characterise the alterations in high energy phosphates that occur during reversible regional ischaemia and to determine whether pyruvate, as the sole exogenous energy substrate, would attenuate the ischaemia induced depletion of the nucleotide pool when compared with glucose. Using phosphorus-31 magnetic resonance spectroscopy baseline concentrations of adenosine triphosphate, phosphocreatine, inorganic phosphate, and intracellular pH were compared with values during 30 min of left coronary artery occlusion followed by 30 min of reperfusion. These variables were related to changes in developed pressure, coronary flow, and oxygen consumption. In addition, the total nucleotide pool was evaluated by biochemical analysis of myocardial tissue extracts and coronary effluent. The ischaemic region was characterised by a dye staining technique and cross sectional echocardiographic measurements of regional myocardial wall thinning. In both glucose and pyruvate perfused groups, coronary flow and oxygen consumption decreased to 50-60% of control within 1 min of ischaemia and returned to baseline values with reflow. Developed pressure decreased to 50(9) and 74(8)% (mean(SEM] of control after 30 min of ischaemia in glucose and pyruvate perfused groups respectively. Reperfusion resulted in complete recovery of developed pressure in hearts perfused with pyruvate but not in the glucose group. Glucose perfused hearts had a greater decrease in intracellular pH during ischaemia (7.07(0.01) to 6.36(0.1] than pyruvate perfused hearts (7.06(0.02) to 6.83(0.04]. Reperfusion resulted in a rapid return to baseline intracellular pH in both groups. During ischaemia, adenosine triphosphate values decreased to a greater degree in glucose than in pyruvate perfused hearts (57(4) and 79(5)% of baseline respectively). Thirty minutes of reperfusion did not significantly improve adenosine triphosphate concentrations in either group. Phosphocreatine concentrations decreased to 52(7) and 75(6)% of baseline in glucose and pyruvate perfused groups respectively after the ischaemic period. Reperfusion resulted in normalisation of phosphocreatine values in the pyruvate but not in the glucose perfused group. Biochemical analysis of myocardial tissue extracts confirmed the spectroscopy data and showed that pyruvate inhibits the efflux of adenine nucleotide derivatives. Tissue concentrations of adenosine monophosphate were three times greater and adenosine 50% less after 30 min of ischaemia in the pyruvate perfused group.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Substrate regulation of the nucleotide pool during regional ischaemia and reperfusion in an isolated rat heart preparation: a phosphorus-31 magnetic resonance spectroscopy analysis. 316 43

The effect of dietary thiamin deficiency has been studied on intestinal functions and chemical composition of brush border membranes in rats. Intestinal uptake of glucose, glycine, alanine, and leucine was significantly stimulated in thiamin deficiency compared to pair-fed control group. Studies with glucose and glycine revealed that stimulation of the absorption process occurs only in the presence of Na+ but not in its absence. Km measured in the presence of 140 mM Na+ for glucose and glycine uptakes was reduced by 56 and 41%, respectively, but Vmax remained unaltered in vitamin deficiency. There was no change in these parameters in Na+-free medium (Km = 31.3 and 23.3 mM; Vmax = 17.2 to 19.7 and 13.5 to 16.4 mumol/10 min/g wet tissue, respectively) under these conditions. The activities of brush border sucrase, lactase, maltase, alkaline phosphatase, and leucine aminopeptidase were reduced by 42 to 66% in thiamin deficiency, compared to pair-fed controls. Kinetic studies with sucrase and alkaline phosphatase evinced that a decrease in Vmax (61 and 64%, respectively) with no change in Km (33.8 and 4.3 mM, respectively) was responsible for observed impairment in the enzyme activities in thiamin deficiency. Microvillus membrane proteins expressed on dry membrane basis were reduced by 20% in thiamin-deficient intestine. There was no difference in membrane sialic acid, cholesterol, phospholipids, and triglycerides fractions under these conditions. It is suggested that thinning of the microvillus membrane may be implicated in observed aberrations of intestinal functions in thiamin-deprived animals.
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PMID:Effect of dietary thiamin deficiency on intestinal functions in rats. 646 54

The effects of systemic cortisol treatment on the biophysical and biochemical properties of skin were investigated. Rats were injected sc with cortisol for 14, 60 and 120 days and samples of lumbar skin were studied. Corticosteroids exert a biphasic effect on the strength of skin: 1) a relatively fast increase in the strength and stability, caused by an increased collagen cross-linking and 2) an inhibited collagen synthesis which ultimately results in a thinning of the skin and a decrease of collagen content consistent with clinical observations. The thermal stability is increased indicating an increased proportion of thermostable cross-links in skin collagen. No changes are observed in the percentage type III collagen with respect to type I collagen. Increased amounts of glucose attached to the epsilon-amino group of lysine residues in the collagen are found after long-term treatments, an alteration which may play a role in hampering the tissue functions.
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PMID:Changes in mechanical properties, thermal stability, reducible cross-links and glycosyl-lysines in rat skin induced by corticosteroid treatment. 681 40

The feasibility of using hydrogel lenticular implants of high water content to alter the anterior corneal curvature for purposes of refractive keratoplasty has been investigated in rabbits. Lenticules (6 mm in diameter) of Permalens (Perfilcon-A) were trephined from contact lens and implanted within an intralamellar pocket in the cornea. The in vitro glucose flux across the hydrogel (0.23 mm thick) was measured at 131 +/- 7 micrograms/cm(2)/hr. For clinical comparison, non-water-permeable disks of Teflon were also implanted. The Teflon implant caused an aseptic ulcer to develop anterior and central to the implant by 9 +/- 4 days. The hydrogel lenticular implant did not cause central ulceration during the 7 month postoperative follow-up. There was a thinning and eventual erosion of the stroma anterior to the edge of the hydrogel implant, 16 +/- 7 weeks. The glycogen contents of the epithelium anterior to (1) the sham operation, i.e., lamellar pocket dissection, (2) the implanted hydrogel lenticule with or without the presence of an erosion, and (3) the control corneas were statistically from the same population. Yet there was a slight dehydration of the stroma anterior to the hydrogel implant when compared to control tissue. A thin-edged implant lenticule design should overcome the stromal thinning caused by the thick-edge implants. During the short-term follow-up, the hydrogel lenticular implant proved to be successful as a refractive keratoplasty implant material.
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PMID:Refractive keratoplasty with intrastromal hydrogel lenticular implants. 725 Dec 94

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

The metabolic changes in neonatal hydrocephalus that lead to permanent brain injury are not clearly defined, nor is the extent to which these changes can be prevented by a cerebrospinal fluid shunt. To clarify these processes, cerebral glucose utilization was examined using [14C]2-deoxyglucose autoradiography in 1-month-old kittens, kaolin-induced hydrocephalic littermates, and hydrocephalic kittens in which a ventriculoperitoneal shunt had been inserted 10 days after kaolin injection. The hydrocephalic kittens showed thinning of the cerebral mantle and an anterior-to-posterior gradient of enlargement of the ventricular system, with a ventricle:brain ratio of 24% for the frontal and 35% for the occipital horns compared with control (< 0.5%) and shunted (< 5%) animals. White matter in hydrocephalic animals was edematous. Myelination was delayed in the periventricular region and in the cores of the cerebral gyri. Glucose utilization in hydrocephalic and shunted animals was unchanged from control animals in all gray-matter regions examined. However, in hydrocephalic animals, the frontal white matter exhibited a significant increase in glucose utilization (25 mumol.100 gm-1.min-1) in the cores of gyri compared with normal surrounding white-matter values (14.8 mumol.100 gm-1.min-1). Very low values (mean 4 mumol.100 gm-1.min-1) were found in areas corresponding to severe white-matter edema, and these areas were surrounded by a halo of increased activity (24 mumol.100 gm-1.min-1). In contrast, cytochrome oxidase activity in white matter was homogeneous. Shunting resulted in restoration of the cerebral mantle thickness, a return to normal levels of glucose utilization in the white matter, and an improvement in myelination. It is suggested that the areas of increased glucose utilization seen in the white matter represent anaerobic glycolysis which, if untreated, progresses to infarction. The pattern of this increased glucose utilization matches that of expected myelination and, during this period of high energy demand, white matter may be susceptible to the hypoperfusion associated with hydrocephalus.
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PMID:Anaerobic glycolysis preceding white-matter destruction in experimental neonatal hydrocephalus. 811 62

Regulation of fluid flow through corneal stroma was investigated in the bullfrog. Corneal specimens were mounted by clamping their limbal sclera between the two chambers of a Ussing-type chamber. The epithelial surface was covered with Ringer's solution, while the endothelial surface was superfused with Ringer's solution at various pressures ranging from 0-60 mm Hg. At 0 mm Hg, the cornea swelled, while at 10 mm Hg the corneal thickness remained unchanged. Further elevation of the hydrostatic pressure of the endothelial superfusion solution caused a decrease in corneal thickness, suggesting that the hydrostatic pressure in the in vivo frog corneal stroma is about 10 mm Hg. At 10 mm Hg of endothelial superfusion pressure, piercing the epithelial cell layer with a 30-gauge needle caused only slight corneal swelling. Removing glucose from the epithelial perfusion solution induced a slowly progressing increase in corneal thickness. Iodoacetate did not interfere with the swelling of the pierced cornea after the removal of glucose from the epithelial perfusion solution. To examine the possibility that the interstitial fluid flows across the stroma-scleral boundary, corneal specimens having unclamped sclera were incubated in Ringer's solution containing 3 mmol/L dextran of various molecular weights ranging from 8800-162,000, and the volume of the preparation was monitored by sequential measurement of the weight. In the presence of dextran with a molecular weight higher than 70,000, the corneal volume decreased at the beginning of incubation, and after reaching the minimal volume it slowly increased, indicating that the stroma-scleral boundary is permeable to dextran of even a molecular weight of 162,000, although dextran molecules diffuse much more slowly than water, and the concentration of unfilterable solutes in the stroma is lower than 3 mmol/L. In experiments using the Ussing-type chamber at 10 mm Hg of endothelial superfusion pressure, a decrease of NaCl in the superfusing solution to 1/2 caused rapid corneal swelling followed by slow recovery. Adding NaCl to the 1/2 NaCl Ringer's solution caused a further corneal thinning in a concentration-dependent manner. The same extent of decrease in corneal thickness as induced by adding NaCl was achieved by the same concentration of glucose as of NaCl, implying that the value of the reflection coefficient of the endothelial cell layer to either Na+ or Cl- is about half that of glucose. Our results show that even a small difference in the concentration of low molecular weight solutes (e.g., Na+ and Cl-) exerts a force that draws water from the cornea.
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PMID:Regulation of fluid flow through corneal stroma in the bullfrog. 950 60

Horizontal canal nerves of 3-, 6-, 9-, and 12-month-diabetic rats were compared with those of age-matched controls. The myelin sheaths of the horizontal canal nerves in diabetic rats were thinner than those of age-matched controls (mean +/- SD 0.63 +/- 0.04 micron (n = 16) vs. 0.71 +/- 0.05 micron (n = 9); p < 0.0001, one-tailed t test). Regression analysis revealed that myelin sheath thickness did not correlate with severity of diabetes, but myelin thinning did occur as a function of the duration of diabetes (p < 0.05, regression ANOVA). The progression of myelin thinning over time is consistent with the possibility of an accelerated decline in vestibular function with age in diabetic patients. That myelin thinning did not correlate with the severity of diabetes suggests that this thinning is not directly related to the aging effects attributed to nonenzymatic glycosylation of myelin proteins. Multivariate analysis revealed a significant difference between diabetic and control groups when fiber diameter and intrasheath diameter were considered together (p < 0.008, canonical discriminant-function analysis). Diabetic and control groups did not differ significantly in total nerve fiber counts. In the diabetic group, however, nerve fiber counts were higher in animals with higher blood glucose levels (p < 0.02, linear-regression ANOVA; r2 = 0.49). The finding of higher nerve fiber counts in more severely diabetic rats is consistent with an earlier transmission electron microscopic finding of false myelinated nerve fiber profiles in micrographs from more severely diabetic rats. These false profiles are believed to represent phagocytosis-like Schwann cell reactions against their own myelin, triggered by excess myelin glycosylation.
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PMID:Morphometric analysis of horizontal canal nerves of chronically diabetic rats. 994 48

The cyanobacterium (blue-green alga) Anabaena sp. ATCC 33047 produces an exopolysaccharide (EPS) during the stationary growth phase in batch culture. Chemical analysis of EPS revealed a heteropolysaccharidic nature, with xylose, glucose, galactose, and mannose the main neutral sugars found. The infrared (IR) spectrum of EPS showed absorption bands of carboxylate groups. The average molecular mass of the polymer was 1.35 MDa. Aqueous dispersions at EPS concentrations ranging from 0.2% to 0.6% (w/w) showed marked shear-thinning properties (power-law behavior). Linear dynamic viscoelastic properties showed that the elastic component was always higher than the viscous component. Viscous and viscoelastic properties demonstrated the absence of conformational changes within the concentration range studied. Stress-growth experiments revealed that 0.4% and 0.6% (w/w) EPS dispersions showed thixotropic properties. A detailed comparison of the linear dynamic viscoelasticity, transient flow, and decreasing shear rate flow curve properties was made for 0.4% (w/w) dispersions of xanthan gum (XG), Alkemir 110 (AG), and EPS. Viscoelastic spectra demonstrated that the EPS dispersion turned out to be more "fluidlike" than the AG and XG dispersions. The flow indexes indicated that the EPS dispersion was less shear-sensitive than that of XG, showing essentially the same viscosity, that is, >50 s(-1). The fact that viscosities of EPS and AG dispersions were not substantially different within the shear-rate range covered must be emphasized, in relation to EPS potential applications. The rheological behavior of EPS dispersions indicates the formation of an intermediate structure between a random-coil polysaccharide and a weak gel.
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PMID:Chemical and rheological properties of an extracellular polysaccharide produced by the cyanobacterium Anabaena sp. ATCC 33047. 1062 Feb 58

Lipodystrophies, characterized by reduction of subcutaneous fat over part or all of the body surface, are uncommon. Their causes are unknown. Recently, lipodystrophy has been reported in human immunodeficiency virus (HIV)-infected patients taking protease inhibitors, which have been recommended since 1996 as standard therapy for HIV disease in combination with nucleoside analogues. In these cases, lipodystrophy consists of an association of peripheral lipoatrophy with central adiposity. We report four HIV-infected men on protease inhibitors who developed a disfiguring lipodystrophy. In three of them, the protease inhibitor was administered for a mean duration of 21.5 months (range 19-23) with good immunological and virological responses. Patient 4 had been treated for 2 years with successive combinations of protease inhibitors with nucleoside analogues without success. The four patients progressively developed an increase in abdominal girth associated with fat wasting of the face and legs. Two of them had recurrent paronychia of the great toes. Triglyceride levels were moderately increased in all patients, and one had a slightly increased cholesterol level. One patient had elevated glucose and insulin plasma levels during a glucose tolerance test. In two patients, a deep biopsy taken from the thigh showed thinning of the subcutaneous fat without other morphological changes. Computed tomographic scans of the face and abdomen confirmed the loss of almost all subcutaneous fat of the cheek and temporal regions, and abdominal perivisceral fat accumulation. For patients 1-3, the protease inhibitor was replaced by a non-nucleoside reverse transcriptase inhibitor. Nine months later, dysmorphic changes had not regressed, but lipid abnormalities had returned to normal and the paronychia had disappeared.
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PMID:Lipodystrophy associated with protease inhibitors. 1073 57


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