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At least 847 records · Page 47Linked to original sources

PubMed2002

[Obesity as a risk factor for the onset of type 2 diabetes mellitus].

Today overweight is the biggest public health problem in the world. According to statistical data, its occurrence is the most frequent among the English 53%, than German 51%, USA 48%, Italian and Spanish 40%, in French 38%, Swedish 30% and Russian 34%. According to available data 0.3% of the BiH population is overweight. Overweight can be related to collection of fat depos--obesity, or enlarged muscle mass--muscle hypertrophy. Criteria for evaluating of overweight are BMI (Body Mass Index). Obesity is the remarkable risk factor for the human health and it performs the background for many diseases--cardiovascular, diabetes mellitus, respiratory diseases, malignant diseases of gastrointestinal tract, joint-bone system diseases etc. For the regulation of optimal body weight, energy balance between input of energy by the food and its consumption is needed.

Diabetes Mellitus, Type 2↗

PubMedDate not supplied

Magnetic resonance image-guided focused ultrasound surgery.

The powerful union of focused ultrasound and magnetic resonance imaging (MRI) has created a new approach to noninvasive surgery. By using this integrated therapy delivery system, the physician can correctly localize tumors, optimally target acoustic energy, monitor energy deposition in real time, and accurately control the deposited thermal dose within the entire tumor volume. This satisfies the requirements for "ideal surgery." In a real sense, MRI provides the "road map" by which focused ultrasound surgery (FUS) is followed. The advantages of MRI over ultrasound guidance in controlling FUS lie in the more sensitive detection of tumor target, the real-time detection of tissue temperature, and the confirmation of thermally induced tissue changes-powerful features that eventually can replace the traditional surgical approach. Applying software that connects the therapy and imaging system (the "Dosimetry Workstation"), the physician can generate an entire treatment plan from quantifying temperature changes to positioning the therapy transducer. The noninvasive debulking of tumors without disturbing adjacent, functionally intact structures is thereby accomplished.

Body Temperature↗

PubMed2002

[Effect of long term administration of finoptin on the morphofunctional state of working cells of the intact myocardium in modeling of chronic coronary insufficiency].

In accordance with the findings on the key role of the cardiomyocite electrolyte homeostasis abnormality in dysfunction and coronary insufficiency-related alterative changes in the contractile myocardium and positive results of correction of the above abnormalities with Ca2+ antagonists morphofunctional aspects were studied of cardioprotective action of finoptin in its course administration in experiments in rabbits. General histological techniques were used together with transmission electron microscopy and cytochemical tests. The drug under study has been shown to increase the cardiomyocite glyco-calyx Ca(2+)-depositing function and to diminish its quickly-exchanging fraction on a plasmolemma. The benefits derived from the aforesaid under conditions of recurring coronary insufficiency include membrane-stabilizing effect, optimization of the energy balance and plastic processes in cardiomyocytes, with their ability to adjust themselves to conditions of the simulated pathology enhanced.

Animals↗

PubMed2003

Percutaneous catheter cryothermal ablation of atrioventricular nodal reentrant tachycardia: efficacy and safety of a new ablation technique.

BACKGROUND: Radiofrequency catheter ablation is nowadays a widely used technique for the treatment of arrhythmias; however, due to the possible complications such as atrioventricular block when radiofrequency is delivered in the septal area, this type of energy is not optimal. In contrast, cryoenergy has several positive features; first of all, it allows for the creation of reversible lesions and hence to test the effects of the ablation while the lesion is still forming thus reducing the number of ineffective and useless lesions. In addition, it also allows for the evaluation of the acute effects on the structures adjacent to the ablation site. The aim of the present study was to analyze the effectiveness and safety of catheter cryoablation in the treatment of atrioventricular nodal reentrant tachycardia (AVNRT). METHODS: Thirty-two patients presenting with AVNRT underwent catheter cryoablation using a 7F catheter. When the optimal parameters were recorded, "ice mapping" at -30 degrees C was performed for 80 s to validate the ablation site by means of a reversible lesion. If the expected result was achieved, the cryoablation was carried out lowering the temperature to -75 degrees C for 4 min thus creating a permanent lesion. RESULTS: Slow pathway ablation guided by a slow pathway potential was successfully performed in 31 out of the 32 patients with a mean of 2.6 +/- 1.0 cryoapplications. No complications occurred in any patients. Transient AH prolongation was observed in 2 patients in a midseptal site during the ice mapping phase of AVNRT ablation. CONCLUSIONS: Cryoablation is a safe and effective technique for AVNRT ablation. It may be useful particularly when the ablation must be performed close to the atrioventricular node or His bundle, due to the possibility of validating the site of ablation by means of ice mapping that creates only a reversible lesion.

Adolescent↗

PubMedDate not supplied

[The dynamics of the amplitude-time parameters of the seismocardiograms of students with different levels of physical fitness].

The reliable scientific data on the physiological mechanisms of the heart activity regulation have been obtained using a seismocardiographic method. Analyzing physical and mental loads of students in different periods of the academic year, it has been revealed that an increase in the amplitude of the first seismocardiographic complex and the development of the amplitude coefficient occur after the maximum cycle-ergometric loading, that is a good response of the contractile myocardium to loading. During the winter term, at rest an increase in the amplitude of the first seismocardiographic complex and a decrease in the amplitude of the second one are observed in most of the students, that is, probably, connected with the emotional and intellectual factors of the session period. The optimal value of energy coefficient per second is set up (it is 1.5 val.). It reflects a relationship between the energy processes during heart systole and diastole.

Adult↗

PubMed2005

Degradation of 2,6-di-tert-butylphenol by an isolated high-efficiency bacterium strain.

An aerobic bacterium strain, F-3-4, capable of effectively degrading 2, 6-ditert-butylphenol (2, 6-DTBP), was isolated and screened out from an acrylic fiber wastewater and the biofilm in the wastewater treatment facilities. This strain was identified as Alcaligenes sp. through morphological, physiological and biochemical examinations. After cultivation, the strain was enhanced by 26.3% in its degradation capacity for 2,6-DTBP. Results indicated that the strain was able to utilize 2,6-DTBP, lysine, lactamine, citrate, n-utenedioic acid and malic acid as the sole carbon and energy source, alkalinize acetamide, asparagine, L-histidine, acetate, citrate and propionate, but failed to utilize glucose, D-fructose, D-seminose, D-xylose, serine and phenylalanine as the sole carbon and energy source. The optimal growth conditions were determined to be: temperature 37 degrees C, pH 7.0, inoculum size 0.1% and shaker rotary speed 250 r/min. Under the optimal conditions, the degradation kinetics of 2,6-DTBP with an initial concentration of 100 mg/L was studied. Results indicated that 62.4% of 2,6-DTBP was removed after 11 d. The degradation kinetics could be expressed by Eckenfelder equation with a half life of 9.38 d. In addition, the initial concentration of 2,6-DTBP played an important role on the degradation ability of the strain. The maximum initial concentration of 2,6-DTBP was determined to be 200 mg/L. Above this level, the strain was overloaded and exhibited significant inhibition.

Alcaligenes↗

PubMed2005

Reactivation of creatine kinase by dithiothreitol prior to use in an in vitro translation extract.

BACKGROUND: In vitro protein synthesis on exogenous messenger ribonucleic acids can be performed in various systems including cytoplasmic extract from eukaryotic cells, rabbit reticulocyte lysate and wheat germ extract. For optimal translation, an energy regeneration system based on creatine phosphate and creatine kinase is commonly employed for the regeneration of the endogenous adenosine triphosphate pools. Creatine kinase purchased from various commercial suppliers can be partially oxidised. Oxidised creatine kinase is not biologically active and might not allow the efficient initiation of translation of exogenous mRNAs in eukaryotic cell extracts in vitro. RESULTS: We successfully used dithiothreitol to reduce and therefore reactivate commercially available creatine kinase. When employed in cytoplasmic extracts obtained from eukaryotic cells grown in monolayers, the reactivated creatine kinase restored translation of the exogenous mRNAs. CONCLUSION: Lyophilised creatine kinase obtained from commercial suppliers can be purchased as an oxidised monomer. The reactivation of creatine kinase using a reducing agent such as dithiothreitol restores the biological activity of this enzyme. This procedure might therefore be extended to various other in vitro conditions and biological systems in which the maintenance of an efficient ATP-regenerating system is critical.

Animals↗

PubMed1988

[The structuro-functional state of the ischemic myocardium under the action of a terrilitin-nicotinic acid mixture in animal experiments].

Histochemical evidence of the activity and distribution of glycolysis redox enzymes, tissue respiration and terminal oxidation pattern (dehydrogenase of lactic, malic, succinic and isocitric acids, NAD-N- and NADPh-N-ase, cytochrome oxidase) as well as the levels of the major carbohydrates (glycogen, neutral aminopolysaccharides, glucose) were experimentally studied in the cardiomyocytes of myocardial necrotic, perinecrotic and intact areas in the control and in the experimental material under the administration of terrilitin-nicotinic acid mixture. It was stated that the use of aforementioned mixture contributed to the retention of enzymatic activity and optimal levels of energy formation in the cardiomyocytes of the marginal infarction zone and noticeably prevented the destructive involvement of the considered area as well as the impairment of functional activity of oscillating cardiomyocytes. Therefore, the application of the mixture improved the outcome prognosis in acute myocardial infarction.

Amylases↗

PubMedDate not supplied

[Parallel DNA double helices. II. Conformational analysis of regular helices having a second order axis of symmetry].

Conformational analysis of double helices of DNA with parallel arranged sugar-phosphate chains connected by twofold symmetry has been performed. Homopolymers poly(dA).poly(dA), poly(dC).poly(dC), poly(dG).poly(dG) and poly(dT).poly(dT) were studied. For each of the homopolymers all variants of H-bond pairing were checked. The maps of closing of sugar-phosphate backbone were previously computed. By the optimization of potential energy the dihedral angles and helix parameters of relatively stable conformations of parallel stranded polynucleotides were calculated. The dependence of conformational energy on the nucleic base character and the base pair type were studied. Two main conformational regions for favourable "parallel" helix of polynucleotides were found. The former of these two regions coincide with the region of typical conformational parameters of B-DNA. On an average the conformational energy of "parallel" DNA is close to the energy of canonic "antiparallel" B-DNA.

DNA↗

PubMedDate not supplied

[Differences in properties of creatine kinase BB from chicken tissues].

BB-creatine phosphokinases (CPK-BB, EC 2.7.3.2) were isolated and purified from the chicken brain, heart and gizzard with specific activities 250-300 IU/mg and equal electrophoretic mobilities. Certain differences in thermal stability, activation energy, Km and optimal temperature of the CPK reaction are shown. The amino acid analysis has also revealed different content of certain amino acids in CPK-BB molecules. The obtained results confirm the existence of tissue-specific heterogeneity in CPK-BB which may be significant for functioning of the phosphocreatine-creatine phosphokinase system in different types of tissues.

Amino Acids↗

PubMed1986

Mechanism of interstrand cross-linking of DNA by anticancer 2-haloethylnitrosoureas.

E and Z-2-haloethyldiazotates, which have been postulated as the ultimate electrophiles responsible for the biological activity of 2-haloethylnitrosoureas (HENUs), have been synthesized and characterized by 15N-nmr. Their stability and solubility in organic solvents are increased by forming crown ether complexes. While E and Z forms are configurationally stable in solution the Z form cyclizes at greater than or equal to -20 degrees C to a 1,2,3-oxadiazoline. The E isomers cross-link DNA, in contrast to the Z isomers. However, both E and Z (2'chloroethyl)thioethyldiazotates (neither of which may cyclize) cross-link DNA extremely efficiently. The cross-linking by these agents is a two-step process and increases with the (G + C) content of the DNA. E-2-chloroethyldiazotate exhibits activity against P388 leukaemia in vivo, lending credence to the suggestion that it is the ultimate electrophile from HENUs. Ab initio calculations predicted the optimized geometry, LUMO energies and atom contributions and the net atomic charges for the diazohydroxides and the HOMO energies and atom contributions for the alternative DNA base sites. An analysis based on Frontier Orbital methods invoking the Hard and Soft Acids and Bases theory permitted an interpretation of the formation of a cross-link site and several modified bases isolated from the reaction of HENUs with DNA.

Animals↗

PubMedDate not supplied

[Prealbumin and the nutritional status of the newborn infant].

Thyroxine-binding prealbumin (TBPA) appears as a sensitive blood parameter for assessing various forms of protein and calorie malnutrition, ranging for subclinical protein deficit to frank kwashiorkor. More precisely, TBPA serves as a valid marker for determining both protein nutritional adequacy and the optimal ratio of energy and zinc to nitrogen intake in healthy newborns and preterm infants without infection. When inflammation is present, the decrease in TBPA blood levels reflects a deterioration in the patient's condition and its increase monitors the efficacy of dietary management. In this latter inflammatory context, it is recommended to combine the measurement of TBPA with that of the most reliable indicators of the phlogistic reaction, allowing the discrimination of both infectious and nutritional poles of the disease spectrum.

Humans↗

PubMed1984

Glucose absorption and weight change in 18 months of continuous ambulatory peritoneal dialysis.

Previous studies have suggested that weight gain is a potential problem for patients using continuous ambulatory peritoneal dialysis (CAPD) due to the influx of glucose from the dialysate. To document the relationship between weight change and glucose absorption, the authors reviewed the medical charts of eight patients from the University of Michigan Hospitals Home Training Dialysis Unit who have used CAPD for at least 18 months. The average daily glucose absorption for each patient was determined by using the equation of Grodstein et al. (y = 11.3(x) -10.9, r = .96, p less than or equal to .001). The mean weight change after 18 months of CAPD was +4.0 +/- 8.9 kg (range = -2.5 to +24.1 kg). Two patients became obese (greater than 120% IBW); one remained obese; four patients maintained desirable weight for height; and one patient became nutritionally depleted (less than 80% IBW). Differences between weights before and after 18 months of CAPD were not significant (p greater than or equal to .05); however, mean weight change was significantly correlated (r = .62, p less than or equal to .05) with average daily amounts of glucose absorbed from the dialysate. This study indicates that nutritional outcomes can be optimized if total energy intake and the passive uptake of significant amounts of glucose across the peritoneal membrane are monitored along with body weight in patients using long-term CAPD.

Absorption↗

PubMed1998

Advantage of appropriate K-edge filters for one-shot dual-energy subtraction sialography.

OBJECTIVES: To determine the optimal added filtration for use for one-shot dual energy subtraction sialography. METHODS: Test phantoms composed of bone and soft tissue materials were imaged with computed radiography using one-shot dual energy subtraction radiography. Eight different additional filter materials were compared with gadolinium contrast. Two numerical measures (absorption ratio and separation index) were used to compare the subtracted images obtained with the various filter/contrast combinations. The K-edge spectra were measured for each filter/contrast combination. A preliminary comparison of a 1.5 M iodine contrast medium with a 1.5 M gadolinium was performed using canine sialography. RESULTS: The gadolinium contrast/samarium filter combination had a larger separation index (P < 0.05). The same combination yielded better sialograms than iodine contrast. CONCLUSIONS: Samarium filter has an optimal k-edge for one-shot dual-energy sialography with gadolinium contrast.

Animals↗

PubMed2003

A prospective dose-finding study of the amount of thermal energy required for laparoscopic ovarian diathermy.

BACKGROUND: This prospective dose-finding study was undertaken to determine the optimal amount of thermal energy required for laparoscopic ovarian diathermy (LOD) in women with polycystic ovary syndrome (PCOS). METHODS: Thirty women with clomiphene-resistant PCOS were included in the study. All women underwent LOD. A modified Monte Carlo up-and-down design was utilized. Women were treated in groups of three (10 groups). The amount of energy applied was standardized at 150 J/puncture. The number of punctures in each group was decreased/increased according to the number of responders in the previous group. The main outcome was ovulation as defined by a serum progesterone concentration of > or =30 nmol/l. RESULTS: Four groups (n=12) were treated with four punctures/ovary, three groups (n=9) with three punctures, two groups (n=6) with two punctures and one group (n=3) with one puncture. Ovulation occurred in 67, 44, 33 and 33% of women treated with four, three, two and one puncture/ovary respectively. The corresponding pregnancy rates were 67, 56, 17 and 0%. The reductions in the free androgen index and the serum concentrations of testosterone and androstenedione after LOD were observed only in women treated with three and four punctures/ovary. CONCLUSION: The clinical response to LOD seems to be dose-dependent, with an increase in the frequency of ovulation and conception with an increasing dose of thermal energy up to 600 J/ovary.

Adult↗

PubMed2002

Design of an optimal Chebyshev-expanded discrimination function for globular proteins.

We describe the construction of a scoring function designed to model the free energy of protein folding. An optimization technique is used to determine the best functional forms of the hydrophobic, residue-residue and hydrogen-bonding components of the potential. The scoring function is expanded by use of Chebyshev polynomials, the coefficients of which are determined by minimizing the score, in units of standard deviation, of native structures in the ensembles of alternate decoy conformations. The derived effective potential is then tested on decoy sets used conventionally in such studies. Using our scoring function, we achieve a high level of discrimination between correct and incorrect folds. In addition, our method is able to represent functions of arbitrary shape with fewer parameters than the usual histogram potentials of similar resolution. Finally, our representation can be combined easily with many optimization methods, because the total energy is a linear function of the parameters. Our results show that the techniques of Z-score optimization and Chebyshev expansion work well.

Amino Acids↗

PubMed2001

Clusters containing open-shell molecules: minimum-energy structures and low-lying isomers of ArnCH (X 2 pi), n = 1 to 15.

The size evolution of the equilibrium structures of open-shell ArnCH (X 2 pi) Van der Waals clusters is investigated for n = 1 to 15. We describe a method for combining pair potentials for Ar-CH and Ar-Ar interactions to obtain potential energy surfaces for ArnCH clusters. For each cluster size considered, the global and a few energetically close local minima are calculated using simulated annealing followed by a direct minimization scheme. Ar2CH is found to have an unusually stable planar structure, which persists as a motif in larger ArnCH clusters and has a strong effect on their optimal geometries. The lowest-energy isomers of ArnCH with n = 3 to 11 have all Ar atoms in a shell around CH. The only exception is Ar4CH, where the fully solvated isomer is 3 cm-1 higher in energy than the optimal isomer with CH bound to the surface of the Ar4 tetrahedron. For n = 7 to 11, the minimum-energy structure of ArnCH derives from the global minimum of the Arn + 1 cluster, by replacing the Ar atom at the bottom of the pentagonal bipyramid with CH. The lowest-energy structure of Ar12CH is that of the optimal icosahedral Ar13 cluster, with CH replacing one of the Ar atoms on the cluster surface. This structure supports the proposition based on the spectroscopic data, that for ArnCH clusters with about 10 to 50 Ar atoms CH resides on the surface of Arn.

Journal Article↗

PubMed2005

Hypothetical binodal zeolitic frameworks.

Hypothetical binodal zeolitic structures (structures containing two kinds of tetrahedral sites) were systematically enumerated using tiling theory and characterized by computational chemistry methods. Each of the 109 refineable topologies based on "simple tilings" was converted into a silica polymorph and its energy minimized using the GULP program with the Sanders-Catlow silica potential. Optimized structural parameters, framework energies relative to alpha-quartz and volumes accessible to sorption have been calculated. Eleven of the 30 known binodal topologies listed in the Atlas of Zeolite Framework Types were found, leaving 98 topologies that were unknown previously. The chemical feasibility of each structure as a zeolite was evaluated by means of a feasibility factor derived from the correlation between lattice energy and framework density. Structures are divided into 15 families, based on common structural features. Many "feasible" structures contain only small pores. Several very open structures were also enumerated, although they contain three-membered rings which are thermodynamically disfavoured and not found in conventional zeolites. We believe that such topologies may be realizable as framework materials, but with different elemental compositions to those normally associated with zeolites.

Computing Methodologies↗