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Biomedical subjects

E M Kovacs

Publications and source records attributed to E M Kovacs.

16 recordsLinked to original sources
PubMed2001

The effect of addition of modified guar gum to a low-energy semisolid meal on appetite and body weight loss.

OBJECTIVE: To investigate the effect of addition of modified guar gum (GG) to a low-energy semisolid meal on appetite and body weight (BW) loss. SUBJECTS: Twenty eight mainly overweight male volunteers (age, 19-56 y; body mass index, 29+/-2 kg x m(-2); BW, 89.4+/-9.2 kg). DESIGN: Baseline of one week with self-selected diet. Three treatments of 2 weeks with a low-energy diet divided over three times a day, consisting of a semisolid meal with (SSM+) or without GG (SSM) or a solid meal (SM) with the same energy content (947 kJ) and macronutrient composition, and a dinner of the subject's own choice. Washout periods lasted 4 weeks. RESULTS: Compared to baseline values, reduction in energy intake and BW loss were similar for SSM+, SSM and SM. Appetite (hunger, desire to eat or estimation of how much one could eat) was increased in SSM and in SM compared to baseline, but not in SSM+. Satiety and fullness in SSM+, SSM and SM were similar to baseline. Any intervention was more effective on BW loss when it took place the first time compared to the second and third times (2.6+/-0.2 kg, 1.7+/-0.2 kg and 1.1+/-0.2 kg, respectively; P<0.001). The SM-SSM+-SSM sequence was more effective on BW loss compared to the SSM+-SSM-SM sequence (5.6+/-1.0 and 2.5+/-0.6 kg, respectively; P<0.05). CONCLUSION: All the three treatments were equally effective with respect to BW loss. GG addition to a semisolid meal prevented an increase in appetite, hunger and desire to eat, which increase was present in the other treatments. However, differences between treatments were not statistically significant. The order effect shows that repeated 2-week bouts of dieting become increasingly ineffective. The sequence SM-SSM+-SSM was more effective than the sequence SSM+-SSM-SM, probably because compliance was relatively higher with the SSM+ or SSM diet, and compliance decreased towards the end of the complete experiment.

Adult↗
PubMed2001

The effects of 2-week ingestion of (--)-hydroxycitrate and (--)-hydroxycitrate combined with medium-chain triglycerides on satiety, fat oxidation, energy expenditure and body weight.

OBJECTIVE: Assessment of the effect of 2-week supplementation with (--)-hydroxycitrate (HCA) and HCA combined with medium-chain triglycerides (MCT) on satiety, fat oxidation, energy expenditure (EE) and body weight (BW) loss. DESIGN: Three intervention periods of 2 weeks separated by washout periods of 4 weeks. Double-blind, placebo-controlled, randomised and cross-over design. SUBJECTS: Eleven overweight male subjects (mean+/-s.d.; age, 47+/-16 y; body mass index, 27.4 +/- 8.2 kg/m(2)). INTERVENTION: Subjects consumed three self-selected meals and four iso-energetic (420 kJ) snacks daily with either no supplementation (PLA), 500 mg HCA (HCA) or 500 mg HCA and 3 g MCT (HCA+MCT). Each intervention ended with a 36 h stay in the respiration chamber. RESULTS: There was a significant BW loss during the 2 weeks of intervention (PLA, -1.0 +/- 0.4 kg, P<0.05; HCA, -1.5 +/- 0.5 kg, P<0.01; HCA+MCT, -1.3 +/- 0.2 kg, P<0.001), but this reduction was not different between treatments. 24 h EE (PLA, 11.8 +/- 0.2 MJ; HCA, 11.7 +/- 0.1 MJ; HCA+MCT, 11.5 +/- 0.1 MJ), 24 h RQ (0.85 +/- 0.00 in all treatments) and the area under the curve of the appetite-related parameters were not different between treatments. CONCLUSION: Two-week supplementation with HCA and HCA combined with MCT did not result in increased satiety, fat oxidation, 24 h EE or BW loss compared to PLA, in subjects losing BW.

Adult↗
PubMed2001

The effect of different dosages of guar gum on gastric emptying and small intestinal transit of a consumed semisolid meal.

BACKGROUND: There is no consensus about the effect of guar gum supplementation on gastrointestinal transit. It has been suggested that guar gum slows gastric emptying and intestinal transit, thus inducing an increased feeling of satiety. OBJECTIVE: To investigate whether addition of guar gum to a semisolid meal affects gastrointestinal transit. DESIGN: Eight male subjects were randomly studied four times. They consumed a standard semisolid test meal containing either 0 g, 2.5 g, 3.5 g, or 4.5 g of guar gum. The test meals contained 1 mCi 99mTc-hepatate for scintigraphy and 5 g lactulose for the H2-breath test. Scintigraphic scanning was performed for at least two hours, and gastric half-emptying time (T1/2) was calculated. Breath samples were collected at 15 minute intervals and analyzed for H2-enrichment. The orocecal transit time (OCTT) was then determined. A parameter of intestinal transit (PIT) was obtained by subtracting the T1/2 from the OCTT. RESULTS: There were no significant differences (in minutes) between the different tests in both T1/2 (0 g, t = 88.2 +/- 11, 2.5 g, t = 83.3 +/- 11.9, 3.5 g, t = 83.3 +/- 13.6, 4.5 g, t = 72.4 +/- 7.2, p = 0.86) and PIT (0 g, t = 149.9 +/- 26.6, 2.5 g, t = 145.5 +/- 25.6, t = 3.5 g, t = 175.3 +/- 17.6, t = 4.5 g, t = 152.6 +/- 22.4, p = 0.52). CONCLUSION: Addition of guar gum to a semisolid meal up to a dosage of 4.5 g does not affect gastrointestinal transit. Other mechanisms than gastrointestinal motility are involved in a possible satiating effect of guar gum supplementation.

Adult↗
PubMed1999

Feline peripheral blood mononuclear cells express message for both CXC and CC type chemokine receptors.

The feline immunodeficiency virus (FIV) causes a disease in cats similar in clinical presentation and disease progression to that of HIV and AIDS. It is now known that, for HIV infection, as well as primary binding of virus to the CD4 receptor, entry and infection of cells requires coreceptors which are members of the chemokine group of G-protein coupled receptors. Because of the similarity of HIV and FIV, we hypothesised that coreceptors are required for the entry and infection of cells by FIV. Using a feline cDNA library derived from a feline IL-2 sensitive lymphocyte cell line, we identified the presence of message for both CC and CXC chemokine receptors. The feline CXCR4 has been shown to facilitate fusion by FIV [44] and we suggest that the feline CCR5 receptor mediates infection of feline cells by M-tropic strains of FIV.

Amino Acid Sequence↗
PubMed1999

Measurement of plasma renin activity with use of HPLC-electrospray-tandem mass spectrometry.

BACKGROUND: The measurement of renin activity is complicated by difficulties in the quantification of angiotensin 1 (Ang1), the product of the renin-catalyzed reaction. We report an HPLC-electrospray-tandem mass spectrometry (HPLC-ESI-MS/MS) method for the quantification of Ang1 as a measure of plasma renin activity (PRA). METHODS: After incubation (37 degrees C for 3 or 18 h), samples were prepared using C18 solid-phase extraction. [Val]5Ang1 was used as the internal standard (IS). Chromatography was performed on a C18 column, using 200 mL/L ammonium acetate buffer-800 mL/L methanol as the mobile phase. The flow rate was 150 microL/min, with a chromatographic run time of 5 min/sample. Mass spectrometric detection was in the positive ionization mode with selected reaction monitoring (Ang1 m/z 649.0-->784.0; IS m/z 641.9-->770.4). RESULTS: The assay was linear over the range 2.5-500 ng Ang1/mL, which corresponded to a limit of detection (signal-to-noise ratio of 3:1) of PRA of 0.14 ng Ang1. mL-1. h-1. The imprecision (CV) of the assay at PRA values of 26.1, 13.5, 3.2, and 0.78 ng Ang1. mL-1. h-1 was 7.0%, 7.0%, 15%, and 11%, respectively. Absolute recoveries were 92.3% (Ang1) and 87.4% (IS). Incubation times of 3 h vs 18 h in the PRA assay gave good agreement at PRA <2 ng Ang1. mL-1. h-1, but samples with a PRA of 2-5 ng Ang1. mL-1. h-1 gave lower PRA results after incubation for 18 h than after 3 h. We compared the HPLC-ESI-MS/MS assay and an RIA for the determination of PRA, with PRA incubation times of 3 h and 1.5 h, respectively. The mean PRA based on RIA of Ang1 was higher than that obtained using HPLC-ESI-MS/MS. CONCLUSION: The HPLC-ESI-MS/MS method allows sensitive and specific measurement of PRA. The higher activities measured with the RIA method highlight its potential for overestimation of PRA.

Chromatography, High Pressure Liquid↗
PubMed1999

Urine color, osmolality and specific electrical conductance are not accurate measures of hydration status during postexercise rehydration.

BACKGROUND: The aim of the study was to determine whether urine color, osmolality and specific electrical conductance (SEC) provide an accurate index of hydration status and of fluid requirements during the recovery phase after an acute exercise-induced dehydration. METHODS EXPERIMENTAL DESIGN: eight well-trained healthy males were dehydrated about 3% of body mass, 3 times, by cycling in the heat. To rehydrate after exercise, three types of drinks frequently consumed by athletes postexercise, i.e. a caffeinated soft drink (CC), a mineral water (MW), or a carbohydrate-electrolyte solution (CES) were ingested ad libitum and in randomized cross-over design during the first 2 hrs of an observation period lasting 6 hrs. MEASURES: urine was sampled each hour for determination of color, osmolality and SEC. Net rehydration was calculated from fluid intake and fluid loss by sweat and urine. RESULTS: Fluid intake amounted 2.6 +/- 0.2 kg for CC, 2.2 +/- 0.2 kg for MW and 2.8 +/- 0.3 kg for CES representing 116%, 96% and 127% of fluid lost by sweat. Urine output showed a negative correlation with color, osmolality and SEC (p < 0.001). These variables were highly interrelated (p < 0.001). However, the level of rehydration did not correlate with any of the measured urinary variables (p > 0.05). CONCLUSIONS: Urine color, SEC and osmolality are poor indicators of hydration status measured from the balance between fluid intake and urine output up to 6 hrs postexercise.

Adult↗
PubMed1998

The effect of different rehydration drinks on post-exercise electrolyte excretion in trained athletes.

Eight well-trained cyclists were dehydrated (median [P25-P75 percentiles]) 3.21 [2.97-3.56]% of body mass by cycling in the heat (28 C). During the first 2 h of recovery, the subjects randomly ingested ad libitum either a caffeinated soft drink (CC), a low Na+ mineral water (MW), or an isotonic carbohydrate-electrolyte solution (CES). Fluid intake and urine loss amounted respectively to 2.77 [2.34-2.85] kg, 1.00 [0.82-1.20] kg for CC, 2.15 [1.86-2.79] kg, 0.96 [0.40-1.49] kg for MW, and 2.86 [2.15-3.58] kg, 1.10 [0.86- 1.50] kg for CES. Electrolyte retention was calculated from electrolyte intake with the drink and loss with the urine. Consumption of CC and MW which were low in electrolytes resulted in marked loss of Na+, K+, Cl-, Mg2+ and Ca2+. Consumption of CES resulted in Na+, Mg2+ and Ca2+ retention while K+ and Cl- loss were not influenced. The significantly lower Na+, Mg2+ and Ca2+ loss with CES compared to both CC and MW may be explained by its higher electrolyte content in CES, compared to CC and MW, which only had minor amounts of these electrolytes. Furthermore, it was shown that CC potentiated urinary Mg2+ and Ca2+ excretion. It is concluded that: 1) Post-exercise MW or CC ingestion results in a negative electrolyte balance, 2) Caffeine containing beverages potentiate Mg2+ and Ca2+ excretion; 3) Consumption of CES containing moderate amounts of Na+, Mg2+ and Ca2+ results in sufficient replacement to compensate for urinary losses.

Adult↗
PubMed1998

Effect of caffeinated drinks on substrate metabolism, caffeine excretion, and performance.

The effect of addition of different dosages of caffeine (Caf) to a carbohydrate-electrolyte solution (CES) on metabolism, Caf excretion, and performance was examined. Subjects (n = 15) ingested 8 ml/kg of water placebo (Pla-W), 7% CES (Pla-CES), or 7% CES with 150, 225, and 320 mg/l Caf (CES-150, CES-225, and CES-320, respectively) during a warm-up protocol (20 min) and 3 ml/kg at one-third and two-thirds of a 1-h time trial. Performance was improved with Caf supplementation: 62.5 +/- 1.3, 61.5 +/- 1.1, 60.4 +/- 1.0, 58.9 +/- 1.0, and 58.9 +/- 1.2 min for Pla-W, Pla-CES, CES-150, CES-225, and CES-320, respectively. The postexercise urinary Caf concentration (range 1.3-2.5 microg/ml) was dose dependent and always far below the doping level of the International Olympic Committee (12 microg/ml) in all subjects. Sweat Caf excretion during exercise exceeded postexercise early-void urinary Caf excretion. Caffeinated CES did not enhance free fatty acid availability, ruling out the fact that performance improvement resulted from enhanced fat oxidation. It is concluded that addition of relatively low amounts of Caf to CES improves performance and that postexercise urinary Caf concentration remained low.

Adult↗
PubMed1992

Inhibition of apoptosis in human tumour cells by okadaic acid.

Gamma-radiation, tetrandrine, bistratene A, and cisplatin were all found to induce pronounced morphological changes characteristic of apoptosis and extensive DNA fragmentation in the human BM13674 cell line 8 h after treatment. Apoptosis induced in BM13674 cells by these diverse agents was markedly inhibited by 1 microM okadaic acid, a tumour promoter that inhibits protein phosphatases 1 and 2A. This compound also inhibited the appearance of apoptosis in fresh human leukaemia cells that had been exposed to gamma-radiation. The inhibition of apoptosis was confirmed using fluorescence microscopy and DNA gel electrophoresis. Dephosphorylation of a limited number of proteins was shown to be associated with apoptosis and okadaic acid prevented these dephosphorylations. Previous studies on the BM13674 cell line showed that an inhibitor of protein synthesis failed to prevent apoptosis in these cells. The present data provides further support that posttranslational modification of proteins, in particular, phosphorylation/dephosphorylation status, plays an important role in inhibition/activation of programmed cell death in different human cells after exposure to several cytotoxic agents.

Acetamides↗
PubMed1991

Cellular processes in atherogenesis: potential targets of Ca2+ channel blockers.

Atherosclerosis is characterized by increased endothelial permeability, monocyte infiltration, intimal smooth muscle cell (SMC) proliferation, platelet aggregation and the accumulation of lipids, calcium and extracellular matrix components in the vessel wall. In various animal studies and recently in humans it could be established that Ca2+ channel blockers delayed the progression of the atherosclerotic process at the stage of early lesions. This review surveys the interaction of Ca2+ channel blockers with various membrane proteins (purinergic receptors, nucleoside transporter, peripheral benzodiazepine receptors, multi-drug resistance protein) which are involved in signal transduction and their potential impact on the observed antiatherosclerotic effects. Although the precise mechanisms have yet to be fully elucidated, it has been clearly shown that these drugs inhibit smooth muscle cell proliferation and migration, improve cellular lipoprotein metabolism in vascular cells, alter phospholipid turnover, decrease platelet adhesion in the vessel wall, reduce extracellular matrix synthesis and protect against radical induced cell damage. Most of these effects are independent of Ca2+ flux across voltage-operated Ca2+ channels. However, all these processes are relevant to the pathogenesis of atherosclerosis and therefore the elucidation of the antiatherogenic mechanisms of Ca2+ channel blockers at the cellular level is of great interest. The future development of Ca2+ channel blockers with altered molecular structures optimized for their antiatherosclerotic targets may provide a useful tool in the therapy of atherosclerosis and risk factor intervention. The protective mechanisms are related to a stabilization of cell membrane integrity, the modulation of secretory activities and cell/cell communication processes rather than to a lowering of plasma lipoprotein levels.

Animals↗
PubMed1969

The possible role of histamine in the coritsone induced gastric acid hypersecretion of the guinea-pig.

1. The effects of cortisone treatment combined with agents influencing histamine metabolism were studied on the free and total acid output in pylorus ligated guinea-pigs.2. It was found that reduction in the synthesis of histamine produced by the administration of alpha-methylDOPA significantly inhibited the acid response to cortisone.3. Enhancement of the oxidative deamination of histamine brought about by the administration of diamine oxidase or heparin inhibited cortisone induced acid hypersecretion significantly.4. Inhibition of the oxidative deamination of histamine by aminoguanidine and iproniazid resulted in a significant increase of the cortisone induced acid hypersecretory response.5. Inhibition of the methylation of histamine by chlorpromazine or 1,4-methylhistamine inhibited the cortisone induced hypersecretory response significantly.6. Studies with labelled histamine indicated that cortisone increases the sequestration of histamine to the stomach.

Amine Oxidase (Copper-Containing)↗
PubMedDate not supplied

Effects of 2-week ingestion of (-)-hydroxycitrate and (-)-hydroxycitrate combined with medium-chain triglycerides on satiety and food intake.

The aim of this study was to assess the effects of 2 weeks of supplementation with (-)-hydroxycitrate (HCA) and HCA combined with medium-chain triglycerides (MCT) on satiety and energy intake. The experimental design consisted of three intervention periods of 2 weeks separated by washout periods of 2 or 6 weeks in a double-blind, placebo-controlled, randomized, and crossover design. Seven male and 14 female normal to moderately obese subjects (mean+/-S.D.; age, 43+/-10 years; body mass index, 27.6+/-2.0 kg/m(2)) participated in this study. Subjects consumed three self-selected meals and four isoenergetic snacks daily with either no supplementation (PLA), with 500 mg HCA (HCA), or 500 mg HCA and 3 g MCT (HCA+MCT). Each intervention period ended with a test day, consisting of a standardized breakfast and ad libitum a lunch and a dinner. There was a significant body weight (BW) loss during the 2 weeks of intervention (PLA, -0.5+/-0.3 kg, P<.05; HCA, -0.4+/-0.2 kg, P<.05; HCA+MCT, -0.7+/-0.2 kg, P<.01), but this reduction was not different between treatments. Twenty-four-hour energy intake (PLA, 8.1+/-0.3 MJ; HCA, 8.3+/-0.3 MJ; HCA+MCT, 8.4+/-0.3 MJ) and the area under the curve of the appetite-related parameters during the test day were similar for all treatments. Two weeks of supplementation with HCA and HCA combined with MCT did not result in increased satiety or decreased energy intake compared to placebo in subjects losing BW.

Adult↗