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M Kohout

Publications and source records attributed to M Kohout.

At least 19 recordsLinked to original sources
PubMed2006

Electron localization function in full-potential representation for crystalline materials.

The electron localization function (ELF) is implemented in the first-principles, all-electron, full-potential local orbital method. This full-potential implementation increases the accuracy with which the ELF can be computed for crystalline materials. Some representative results obtained are presented and compared with the results of other methods. Although for crystal structures with directed bonding only minor differences are found, in simple elemental metals, there are differences in the valence region, which give rise to different ELF topologies.

Journal Article↗
PubMed2003

Features of the electron density in magnesium diboride: reconstruction from X-ray diffraction data and comparison with TB-LMTO and FPLO calculations.

Features of the electron density in MgB(2) reconstructed from room-temperature single-crystal X-ray diffraction intensities using a multipole model are considered. Topological analysis of the total electron density has been applied to characterize the atomic interactions in magnesium diboride. The shared-type B-B interaction in the B-atom layer reveals that both sigma and pi components of the bonding are strong. A closed-shell-type weak B-B pi interaction along the c axis of the unit cell has also been found. The Mg-B closed-shell interaction exhibits a bond path that is significantly curved towards the vertical Mg-atom chain ([110] direction). The latter two facts reflect two sorts of bonding interactions along the [001] direction. Integration of the electron density over the zero-flux atomic basins reveals a charge transfer of approximately 1.4 (1) electrons from the Mg atoms to the B-atom network. The calculated electric-field gradients at nuclear positions are in good agreement with experimental NMR values. The anharmonic displacement of the B atoms is also discussed. Calculations of the electron density by tight-binding linear muffin-tin orbital (TB-LMTO) and full-potential non-orthogonal local orbital (FPLO) methods confirm the results of the reconstruction from X-ray diffraction; for example, a charge transfer of 1.5 and 1.6 electrons, respectively, was found.

Journal Article↗
PubMed1998

New instrument for orbital anthropometry.

A new instrument for orbital anthropometry is described. It consists of the base for a slit-lamp upon which the patient's head rests and rulers mounted on three independently movable axes. The z-axis probe is used to measure sagittal relationship between the corneal apices and points on the orbital perimeter. The instrument was tested against a sliding caliper and its accuracy was found to be within 0.2 mm or 2%. Intra- and inter-observer reliability were assessed by repeated measurements of two subjects by three observers. The intra-observer reliability was 0.99. Variations between observers was not significantly different for points orbitale inferius (oi), nasion (n), and orbitale superius (os), however, there was a statistically significant difference for measurement of orbitale laterale (ol). The correlation between anthropometric readings for lateral orbital wall to apex corneal (ol-ac) and CT scans for the same landmarks was assessed. Analysis of variance showed no difference between the measurement methods. This anthropometer is convenient and accurate for measurement of the sagittal orbital-globe relationships. A disadvantage is that it cannot be used intraoperatively.

Analysis of Variance↗
PubMed1995

Cool perfusion solutions for skin flaps: a new mixture of pharmacological agents which improves skin flap viability.

This study tested the hypotheses that perfusion of cooled skin flaps with established organ preservation solutions improves their viability and that this improvement can be further enhanced by pharmacological manipulation. Rabbit epigastric skin flaps were perfused with different solutions before explantation and stored at 8 degrees C for 6 days. In the first part of the experiment, flap viability was assessed 7 days after reperfusion of the flap via microvascular anastomoses. The different solutions were heparinised blood, University of Wisconsin solution, two of its modifications, EuroCollins solution and a pharmacological mixture containing phosphoenolpyruvate, desferrioxamine, nitrendipine, dextran 70 and a platelet-aggregating factor receptor antagonist (WEB 2170). In the second part, biochemical parameters of skin were measured at various reperfusion times. Adenosine triphosphate (ATP), reduced glutathione (GSH), myeloperoxidase (MPO) and tissue water were assayed at 0, 1, and 24 h after reperfusion. In addition, plasma thromboxane (TXB2) was measured at 0, 30 and 60 minutes after reperfusion. The viability of flaps perfused with the mixture (81%) was significantly higher than that of any of the other groups (39% for controls, 38% for EuroCollins, 13% for UW solution, 27% and 31% for its modifications). ATP levels after reperfusion were higher in the mixture group than in UW-perfused group. GSH levels in the mixture group were also higher than in the UW group, indicating higher level of protection against oxidative stress during reperfusion. There were no differences in MPO levels. Thromboxane levels associated with UW-perfused flaps were significantly higher than those associated with any other perfusion solution. In conclusion, perfusion of a mixture of pharmacological agents targeting specific aspects of ischaemia/reperfusion injury improved the viability of skin flaps stored in the cold for 6 days, whereas standard organ preservation solutions failed to affect significantly skin flap survival.

Adenosine↗
PubMed1993

Metabolic effects of omega-3 fatty acids in type 2 (non-insulin-dependent) diabetic patients.

The metabolic effects of a 3-week dietary supplement of a fish oil concentrate was examined in mildly obese, normotriglyceridemic men with non-insulin-dependent diabetes mellitus (NIDDM) treated with hypoglycemic agents (n = 20). Patients were randomized into two groups, receiving 15 ml per day of fish oil (Martens Oil, Norway) containing 3.1 g of omega-3 fatty acids (FA) (n = 10) or placebo (n = 10). Whereas fish oil led to the expected increase in the ratio of omega-3 to omega-6 FA in serum phospholipids, reflecting the increase in omega-3 FA intake, it did not alter fasting or mixed meal stimulated blood glucose, plasma insulin, and C-peptide concentrations. No changes in insulin action were noted, estimated by the metabolic clearance rates of glucose at plasma insulin levels of approximately 100 microU/ml and 1,400 microU/ml during a hyperinsulinemic, isoglycemic clamp; no changes were seen in insulin binding to erythrocytes. We conclude that during short-term administration, no adverse effects of low dose fish oil on glucose homeostasis were found in mildly obese NIDDM patients treated with oral hypoglycemic agents.

Adult↗
PubMed1993

[Glucose utilization and risk of hyperglycemia during simultaneous administration of branched-chain amino acids and fat emulsions in healthy persons].

In order to evaluate the effect of substrate competition on glucose utilization, we studied 8 healthy volunteers under three different conditions: 1. Hyperinsulinemic (75 a 550 microU/ml) euglycemic (5 mmol/1) clamp (HEC). 2. HEC with Nutramin VLI infusion given at a rate of 2 ml/kg.h. 3. HEC with infusion of Nutramin VLI (2 ml/kg.h) and Intralipid (0.15 g of fat/kg.h). Glucose utilization was evaluated as the glucose disposal rate during HEC. We have found, that Nutramin VLI given alone or with Intralipid does not significantly decrease glucose utilization at insulinemia of about 75 and 550 microU/ml. We conclude that simultaneous administration of substrates during parenteral nutrition at standard rates does not raise the risk of hyperglycemia in healthy men.

Adult↗
PubMed1992

[The effect of fish oil on the secretion and effect of insulin in patients with type II diabetes].

The metabolic effect of 3-week dietary supplementation with a fish oil concentrate was examined in not markedly obese, not hypertriglyceridemic men with non-insulin-dependent diabetes mellitus (NIDDM) treated with hypoglycemic agents. Ten patients were given 15 ml/d of fish oil (Martens Oil, Norway) equivalent to 3.1 g of n-3 fatty acid (FA) per day, and compared to 10 diabetics treated with placebo (15 ml/d saline). While fish oil leads to expected increase in the ratio of n-3 to n-6 FA intake, it does not alter fasting and mixed meal stimulated blood glucose, plasma insulin and C-peptide concentrations. There were no changes in insulin action estimated by the metabolic clearance rates of glucose at plasma insulin levels of about 100 microU/ml and 1400 microU/ml during hyperinsulinemic isoglycemic clamp, and no changes were seen in insulin binding to erythrocytes. Even though our short-term study does not warrant authoritative conclusions, no adverse effects of low-dose fish oil on glucose homeostasis have been found in not markedly obese NIDDM patients treated with oral hypoglycemics.

Adult↗
PubMed1991

Effect of acute hyperinsulinemia on fatty acid composition of serum lipids in non-insulin-dependent diabetics and healthy men.

The fatty acid pattern of serum phospholipids, cholesteryl esters, triglycerides and free fatty acids was measured before and after a 5-h two-step euglycemic hyperinsulinemic clamp (75 and 1400 microU/ml) in 21 non-insulin-dependent diabetics and 14 age-, weight-, and sex-matched healthy controls. Acute hyperinsulinemia was associated with a statistically significant increase in essential fatty acid and a decrease in non-essential fatty acid contents in triglycerides while the levels of serum triglycerides and free fatty acids dropped in both groups. The fatty acid composition of phospholipids and cholesteryl esters remained unchanged as did the levels of serum phospholipids, total cholesterol and HDL cholesterol.

Adult↗
PubMed1991

Fatty acid composition of serum lipids and erythrocyte membranes in type 2 (non-insulin-dependent) diabetic men.

The fatty acid (FA) composition of serum lipids and erythrocytes was studied in 21 men with non-insulin-dependent diabetes mellitus (NIDDM) and in 14 normal subjects matched for age, sex, body weight, and dietary intake. Lower levels of linoleic acid and higher levels of highly unsaturated FA (daughter) of n-3 and n-6 family FA, reflected in a higher unsaturation index, were found in serum phospholipids (S-PL), in phospholipids of erythrocyte membranes (ery-PL), and in serum cholesterolesters (S-CHE). The unsaturation index of serum phospholipids significantly correlated with glycosylated hemoglobin A1c (P less than .05) and blood glucose levels after glucose load (P less than .001). The results suggest that elongation and desaturation of essential FA (linoleic acid in particular) are increased. The above changes may be associated with accelerated atherosclerosis in type 2 diabetics.

Adult↗
PubMed1990

[Insulin secretion and insulin resistance in type II diabetes. Relation to fatty acid composition of serum phospholipids].

Non-obese middle-aged men (n = 21) in an early stage after manifestation of Type 2 diabetes mellitus, and free of signs of atherosclerotic complications, when compared with an age-, weight- and sex-matched control group (n = 14), were found to show: 1. a decrease in linoleic acid content and increase in polyunsaturated elongated forms of n-6 and n-3 families fatty acids in serum phospholipids; 2. fasting hyperinsulinemia and impaired dynamics of insulin secretion after glucose load; 3. insulin resistance due to both receptor and postreceptor defect. Under physiologic conditions (i.e., in the control group), the drop in linoleic acid content and the rise in saturated fatty acids were associated with increased insulin secretion, and decrease in maximal insulin action. The nature of the changes in fatty acid pattern, the decrease in linoleic acid in particular, resembles findings made in persons who died middle-aged from serious complications of atherosclerosis. Combined with the relationship between the fatty acid composition of lipids and insulin secretion and action, our findings suggest a common metabolic defect of atherosclerosis and Type 2 diabetes which is probably insulin resistance in glucose metabolism.

Adult↗
PubMed1990

Cardioprotective conditioning with glucose and insulin prior to cardiac surgery involving ischaemic cold arrest.

The study describes cardioprotective conditioning by means of high doses of glucose together with insulin and potassium. Eighteen hours before cardiac surgery, nine patients received continuous infusion of 1000 ml of 40% glucose solution along with 112 U of insulin and 60 mmol of potassium. Before and after ischaemic cold arrest, the myocardial a--v differences of lactate, pyruvate, glucose, Na, K, Cl, Ca, P, free fatty acids and triglycerides were analysed in all patients. Blood collections were performed in parallel with ultramicroscopy of biopsy specimens from the right atrium. The results were compared with those obtained in a control group of 22 patients without cardioprotective conditioning with glucose, insulin and potassium. Neither the analysis of the myocardial a--v differences of metabolites, nor the finding on the mitochondria and myofibrils documented statistically significant differences between the control and conditioned groups. Following termination of ischaemic cold arrest, patients in the conditioned group exhibited more glycogen grains in myocardial cells than those in the control group. While 34% of patients in the control group were defibrillated after revascularization, it was not necessary in any of the conditioned patients.

Adult↗
PubMed1989

[Hyperglycemia, hyperinsulinism, atherosclerosis].

The paper deals with a group of 117 patients with clearly defined clinical signs of atherosclerosis following myocardial infarction appearing in middle age, analyzes relationship between indicators of saccharide metabolism and cardiovascular morbidity within a ten-year period, and discusses its potential cause. Fasting levels taken at 120 minutes after the administration of glucose and the sum of the fasting level and three stimulated levels of blood sugar, or insulin (IRI), were compared with 54 controls as well as within the group of patients. Compared with the control group, the patients had glycemia levels elevated. In the group of patient with ischaemic heart disease (glycemia levels especially the sum but also glycemias at 120 min.) were elevated in persons with signs of ischaemic disease of lower extremities, with hypertension, in cases with increased serum triacylglyceroles, with increased energy intake (including fasting levels). The sum of insulin kept increasing in cases with familial disposition to atherosclerosis, with clinical progression of atherosclerosis over a period of 5 years (non-fatal reinfarctions). This had a highly significant correlation with linoleic acid in total serum lipids suggesting correlation with cardiovascular morbidity. This finding stresses the necessity of a comprehensive view of deviations in sacharide metabolism, especially as regards the relationship between elevated glycemia and cardiovascular morbidity, and between insulin and mortality-causing factors.

Arteriosclerosis↗
PubMed1989

Insulin binding to erythrocytes and fatty acid composition of erythrocyte membrane phospholipids in healthy men.

The relationship between specific insulin binding to insulin receptors on erythrocytes and erythrocyte membrane phospholipid fatty acid pattern was evaluated in 11 healthy men. A significant negative correlation between insulin binding and the proportion of w-6 family essential fatty acids, especially linoleic acid (r = -0.82, p less than 0.01) and arachidonic acid (r = -0.73, p less than 0.05) in erythrocyte membrane was found. On the other hand significant positive correlation between insulin binding and the content of nonessential fatty acids (r = +0.65, p less than 0.05) was seen. Data presented support the hypothesis that the fatty acid composition of membrane phospholipids may modify properties of insulin receptors.

Adult↗
PubMed1989

Insulin secretion and insulin action related to the serum phospholipid fatty acid pattern in healthy men.

In order to decide whether the phospholipid fatty acid pattern is related to variables determining glucose tolerance, 11 healthy volunteers with normal glucose tolerance were studied. The relationship was evaluated between the proportions of individual fatty acids (FA) in serum phospholipids and (1) insulin secretion, determined by fasting and postglucose plasma insulin levels, and (2) in vivo insulin action, assessed as metabolic clearance rates of glucose during euglycemic clamp studies at two insulin concentrations of approximately 70 microU/mL (MCRglu70) and 500 microU/mL (MCRglu500). It was found that both insulin secretion and insulin action are significantly related to the ratio of omega-6 class essential FA to saturated FA in serum phospholipids. An increase of this ratio is associated with a decrease in total insulin response (r = -0.84, P less than .01), and an increase in MCRglu70 (r = .66, P less than .05) and MCRglu500 (r = .82, P less than .01). The data presented support the hypothesis that phospholipid FA composition might play a role in blood glucose regulation.

Adult↗
PubMed1989

Interrelationship between glucose and fat utilisation during simultaneous IV administration of glucose and lipid emulsion in healthy man.

In order to evaluate the interaction between glucose and fat utilisation during parenteral nutrition, we studied 12 healthy volunteers under three different conditions: While Intralipid infusion does not alter the glucose utilisation, measured by metabolic clearance rate of glucose at an insulin level of about 80 uU/ml (MCR(glu)submax) 11.3 +/- 1 v.s. 11.48 +/- 0.9 ml/kg/min) and the sensitivity index, it decreases glucose utilisation at an insulin level of about 550 uU/ml (MCR(glu)max) (17.8 +/- 1.3 v.s. 15.9 +/- 0.9 ml/kg/min, p < 0.05) suggesting postreceptor alterations in insulin action. Simultaneous administration of Intralipid with glucose and insulin is associated with a smaller increase in serum triglycerides than the infusion of Intralipid alone (2.56 +/- 0.4 v.s. 5.44 +/- 0.5 mmol/lm p < 0.001). We conclude that, when infused at standard rates, Intralipid does not decrease glucose utilisation significantly and, at the same time, its own clearance is enhanced by glucose and insulin.

Journal Article↗
PubMed1989

Erythrocyte insulin receptor characteristics and erythrocyte membrane lipid composition in healthy men.

The cell membrane plays an important role in the mechanism of insulin action. To test whether erythrocyte insulin receptor characteristics are related to the erythrocyte membrane lipid composition, 11 healthy volunteers were studied. The relationship between insulin binding to erythrocytes, the number of receptors per cell and the affinity of receptors to insulin on the one hand and total phospholipid fatty acid (FA) composition and cholesterol/phospholipid molar ratio in the erythrocyte membrane on the other hand were evaluated. 1. We found a significant negative correlation between specific insulin binding and the proportion of n-6 essential FA in erythrocyte membrane phospholipids, especially linoleic acid (r = -0.82, p less than 0.01) and arachidonic acid (r = -0.73, p less than 0.05). On the other hand, a significant positive correlation between insulin binding and the proportion of nonessential FA (r = +0.65, p less than 0.05) was seen. Number of receptors per cell and the affinity of receptors were not significantly related to phospholipid FA composition. 2. There was no significant correlation between insulin receptor characteristics and the cholesterol/phospholipid molar ratio in the erythrocyte membrane. The data presented support the hypothesis that the FA pattern of membrane total phospholipids may modify the properties of insulin receptors.

Adult↗
PubMed1989

[Metabolic and ultrastructural changes in the myocardium during heart arrest in patients undergoing surgery for ischemic heart disease].

The authors give an account of metabolic changes in the ultrastructure of the myocardium which develop during cardioplegic arrest of the heart muscle by cold during aortocoronary reconstruction operations. Using the technique of arteriovenous differences before myocardial ischemia and after its termination, the assessed differences in arterial blood and blood from the sinus coronarius as regards the blood sugar level, lactate, pyruvate, potassium, phosphorus, unsaturated fatty acids and triglycerides. The results revealed a marked disorder of the carbohydrate and ion metabolism and severe impairment of the ultrastructure of the heart muscle during cardiac arrest.

Adult↗