Antimycobacterial activity of 1-deaza-7,8-dihydropteridine derivatives against Mycobacterium tuberculosis and Mycobacterium avium complex in vitro.
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Twenty-five 1-deaza-7,8-dihydropteridine derivatives were screened for antimycobacterial activity against Mycobacterium tuberculosis strain H37Ra and three Mycobacterium avium clinical isolates (serovar 1, 4 or 6). Antibacterial activity was determined with a colorimetric microdilution broth assay. Seventeen of the compounds inhibited growth in the range >1.28 to +info)
Ca2+ and phosphate releases from calcified Chara cell walls in concentrated KCl solution.
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Ca2+ and P(i) (inorganic phosphate) releases from isolated calcified and uncalcified Chara cell walls were measured with a Ca(2+)-selective electrode and colorimetry, and their ionic relations were analysed on the basis of the electroneutrality rule. The results showed that (1) not only Ca2+ but also P(i) can be released from isolated calcified Chara cell walls into pure deionized water and 100 mM KCl solution, and (2) the positive charge due to the Ca2+ released cannot be neutralized only by the negative charge from the simultaneously released P(i). These findings suggest that calcium bands of calcified Chara cell walls are composed of mainly CaCO(3) and CaHPO(4) and some anions other than P(i) should be released simultaneously with the Ca2+ and P(i). More Ca2+ and P(i) can be solubilized from isolated Chara cell walls in 100 mM KCl solution than in pure deionized water. The pH value of 100 mM KCl solution in which isolated uncalcified young Chara cell walls have been immersed is a little lower than that of pure deionized water in which the same isolated uncalcified young Chara cell walls have been immersed, suggesting that some acidic substances are solubilized by 100 mM KCl. To explain this from the viewpoint of solution chemistry, the solubilities of pure CaCO(3) and pure CaHPO(4) in water and 100 mM KCl solution were measured with a Ca2+ -selective electrode and their pH values with a glass pH electrode. The conclusion reached was that the Ca2+ release from isolated Chara cell walls is accompanied by the release of P(i), CO(2-)(3) and acidic substances. This suggests that the so-called calcium bands and/or ionic relations, including ion exchange, in Chara cell walls are chemically or physicochemically more complex than they are currently considered to be. (+info)
Comparison of enamel colour changes associated with orthodontic bonding using two different adhesives.
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The purpose of this study was to evaluate the enamel colour changes associated with bonding of brackets with a no-mix (one-phase) adhesive resin (Unite) and a glass-ionomer adhesive (GC Fuji Ortho). Thirty recently extracted premolars were used in the investigation. Black rectangular pieces of adhesive tape with a 3-mm diameter window were used to standardize the enamel surface intended for analysis. The teeth were divided into two groups of 15 teeth each, brackets (Starfire TMB) were bonded with the two adhesives, and the enamel surfaces were colourimetrically evaluated at three time intervals: (a) before bonding (baseline), (b) following debonding and cleaning, and (c) after artificial photo-ageing for 24 hours. The CIE colour parameters (L*, a*, b*) were recorded and averaged for each material, interval group, and the corresponding colour differences (delta E) were calculated. The results were statistically analysed using two-way ANOVA repeated measures, and Scheffe multiple range test at alpha = 0.05 level of significance. All differences noted exceeded the threshold for clinical detection (delta E = 3.7). The highest differences were recorded for the baseline-debonding interval for both adhesives used. No difference was found with respect to delta E between etching-mediated and no etching-mediated bonding implying that the debonding cleaning process involving adhesive grinding may be more invasive relative to acid etching with regard to enamel colour alterations. (+info)
Effectiveness of peritoneal lavage in blunt abdominal trauma.
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To analyze the effectiveness of peritoneal lavage and to define its limitations in the evaluation of patients who have sustained blunt abdominal trauma, a prospective study of 500 such patients was undertaken by the Trauma Service at the Naval Hospital, San Diego. Utilizing a qualitative colorometric method to evaluate the degree of hemoperitoneum, patients could rapidly be divided into three clinical groups: strongly positive, weakly positive, and negative. Using this method, patients with a strongly positive peritoneal lavage had a 94% incidence of significant intra-abdominal injuries. In 333 patients with a negative lavage, there was no documented incidence of significant intra-abdominal injuries. Visceral angiography and abdominal echography were utilized in this group of patients to identify those with significant intra-abdominal injuries. By utilizing this approach, there were only eight unnecessary celiotomies in the total group of 500 patients. It is concluded, therefore, that peritoneal lavage is a safe, rapid, and effective means of evaluating patients who have sustained blunt abdominal trauma. (+info)
Enzymic determination of fructose in seminal plasma by initial rate analysis.
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We describe a spectrophotometric assay for fructose in seminal plasma. The method is based on reduction of fructose by a commercially available preparation of sorbitol dehydrogenase (EC 1.1.1.14), with the concomitant oxidation of NADH. The initial rate of NADH oxidation, which is proportional to the fructose content of seminal plasma, can be measured either with a recording spectrophotometer or by conventional two-point kinetic assay. The method was as accurate, precise, and sensitive as, and more specific and rapid than, currently used colorimetric (resorcinol) methods for fructose determination. Values (mmol/L) for fructose in seminal plasma from several species are: man, 9 +/- 2 (SD); cynamolgus monkey (Macaca fasicicularis)., 108 +/- 19; bull, 30 +/- 1; and rabbit, 13 +/- 4. These values agree with previously published results. We believe the method is appropriate for both research and clinical use. (+info)
Is salivary histatin 5 a metallopeptide?
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Histatins are small histidine-rich salivary polypeptides which exhibit antimicrobial activity against Candida albicans. This antimicrobial activity has been ascribed in part to a high content of basic amino acids. However, unlike most other antimicrobial proteins histatins have a high content of histidine, tyrosine and acidic amino acids known to participate in metal ion coordination. This study was conducted to test whether histatin 5 could bind zinc and copper which are metals present in salivary secretions and whole saliva. Physical binding parameters and spectral properties of zinc- and copper-histatin complexes were investigated in order to obtain direct evidence of these interactions. A spectrophotometric competition assay using the metallochromic indicator murexide showed that histatin 5 dissociates metal indicator complexes containing zinc or copper ions. Absorption spectra of histatin 5 at increasing copper chloride concentrations resulted in higher absorbance in the 230-280 nm wavelength range and this spectral change was saturated at a peptide:metal molar ratio of approx. 1:1. A corresponding band was observed in the visible range of the spectrum with a maximum and molar extinction coefficient corresponding to that of copper binding to an ATCUN motif. Quantitative assessment of zinc and copper binding to histatin 5 using isothermal titration calorimetry revealed at least one high affinity site for each metal, with binding constants of 1.2x10(5) and 2.6x10(7) M(-1), respectively. These results indicate that histatin 5 exhibits metallopeptide-like properties. The precise biological significance of this has not yet been established but histatins may contribute significantly to salivary metal binding capacity. (+info)
Kanamycin susceptibility testing of Mycobacterium tuberculosis using Mycobacterium Growth Indicator Tube and a colorimetric method.
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Two novel systems were evaluated for performing indirect kanamycin susceptibility tests on 72 strains of Mycobacterium tuberculosis. The microplate Alamar blue colorimetric method (breakpoint, 2.5 microg/ml) and the Mycobacterium Growth Indicator Tube (MGIT) system (breakpoint, 5.0 microg/ml) both produced 98.6% agreement when compared with the conventional proportion method performed on 7H10 agar using 5.0 microg of kanamycin/ml. Both systems provided results within an average of 1 week. (+info)
Maternal and transplacental kinetics of trimethoprim and sulfamethoxazole, separately and in combination.
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The fate of trimethoprim and sulfamethoxazole and the combination of both these agents was studied in a group of healthy pregnant women who were undergoing therapeutic abortion. Assays were performed on samples of blood, urine, amniotic fluid and fetal tissues, using a standardized protocol for the selection of patients, dose administration, sample collection and assay techniques. A comparative evaluation of kinetics to assess the maternal handling and the distribution of trimethoprim throughout the fetoplacental unit disclosed no significant difference in the concentration within fetal fluids and tissue compartments. On the other hand, the concentration of sulfamethoxazole was lower in fetal tissues than in fetal fluids when relative ratios to trimethoprim were compared. The implications of the difference in behaviour of pharmacokinetic and clinical points of view. (+info)