Trichinellosis in Chile (1980-1993).
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Animals↗
Biomedical subjects
A Rojas
Publications and source records attributed to A Rojas.
Effects of glucose, ethanol, Hg(II) and Cu(II) on almond beta-glucosidase.
The kinetic parameters of almond beta-glucosidase (beta-D-glucoside glucohydrolase; EC 3.2.1.21), using pNGP as substrate were kM = 2.24 +/- 0.11 mM and Vmax 588 +/- 25.1 U/mg protein. Only Hg(II) and Cu(II) showed irreversible inactivation of the enzyme. However, when these metals were present in the reaction system the inhibition effects were consistent with a mixed-type inhibition pattern (Cu(II) ki: 5.08 mM and Hg(II) ki: 0.07 mM). The glucose kinetic effect was also consistent with a mixed-type inhibition (ki = 406 mM) pattern with pNGP as varied substrate. Ethanol displayed the kinetic pattern of competitive inhibition (ki = 640 mM).
Amino Acid Sequence↗
[Asymptomatic bacteriuria and pyuria during pregnancy].
BACKGROUND: The presence of pyuria and the role of mixed culture in the diagnosis of asymptomatic bacteriuria in pregnant women have been evaluated METHODS: One hundred and sixty four pregnant women without any symptomatology have been studied using two cultures of mid-stream urine samples and pyuria quantification. In addition culture of bladder urine has been carried out in 17 of these patients (12 with pure cultures and 5 with mixed cultures). RESULTS: 110 samples were culture negative without pyuria; 7 were pure cultures with pyuria; 19 pure culture without pyuria and the remaining 28 patients yielded mixed culture with or without pyuria in the first culture. Twenty of these 28 mixed cultures were negative in the second culture. A estimated frequency of asymptomatic bacteriuria in pregnancy was 16% and pyuria was only found in 27% of pregnant women with asymptomatic bacteriuria. CONCLUSION: The pyuria is not a useful marker for the diagnosis of asymptomatic bacteriuria in pregnancy.
Bacteria↗
Monocyte chemotactic protein-1 inhibits the induction of nitric oxide synthase in J774 cells.
We evaluated the effect of monocyte chemotactic protein-1 (MCP-1) on the induction of nitric oxide synthase activity in J774 cells. MCP-1 was able to inhibit the production of nitric oxide induced by LPS and IFN-gamma in a dose-dependent manner. Moreover, the inhibition was only achieved when the cells were pretreated with MCP-1. No inhibition was observed when MCP-1 was added after stimulation with LPS and IFN-gamma. These results demonstrate that MCP-1 is able to inhibit the induction of nitric oxide synthesis.
Amino Acid Oxidoreductases↗
Chlorpromazine inhibits both the constitutive nitric oxide synthase and the induction of nitric oxide synthase after LPS challenge.
The effects of chlorpromazine on either the activity of mouse brain nitric oxide synthase or the induction of lung nitric oxide synthase in mice and rats were studied. Chlorpromazine inhibited the nitric oxide synthase activity in mouse brain cytosol. This effect could be reversed by adding an excess of calmodulin. In addition, chlorpromazine was able to inhibit the induction of lung nitric oxide synthase, in both species, after LPS administration. Furthermore, chlorpromazine also inhibited arginase activity in mouse lung cytosol.
Amino Acid Oxidoreductases↗
Role of nitric oxide pathway in the protection against lethal endotoxemia afforded by low doses of lipopolysaccharide.
Survival after lipopolysaccharide challenge (LD80, 20 mg.kg-1, i.p.) was significantly enhanced by previous treatment with a microdose of LPS (50 micrograms.kg-1, i.v.). When NG-monomethyl-L-arginine, a specific inhibitor of the formation of nitric oxide from L-arginine, was given 30 minutes before microdose, survival was significantly reduced. When we monitored the serum Tumor Necrosis Factor (TNF) levels in both groups a significant reduction of TNF level after the microdose was observed in mice previously treated with L-NMMA. The ability of L-NNMA to reduce TNF release was dose dependent.
Animals↗
Pharmacokinetics of varying doses of nicotinamide and tumour radiosensitisation with carbogen and nicotinamide: clinical considerations.
Plasma concentrations, after administration of varying doses of nicotinamide, were measured in CBA male mice using a newly-developed high performance liquid chromatography assay. In all dose groups, peak levels were observed within the first 15 min after an i.p. administration of 0.1, 0.2, 0.3 or 0.5 mg g-1 of nicotinamide. There was a clear dose-dependent increase in plasma concentration with increasing dose, with almost a five-fold lower concentration (1.0 vs 4.9 mumol ml-1) achieved with a dose of 0.1 mg g-1 compared with 0.5 mg g-1, respectively. The half-life of nicotinamide increased from 1.4 h to 2.2 h over the dose range (P < 0.01). Comparisons with previous pharmacokinetic data in humans show that clinically-relevant oral doses of 6 and 9 g in humans give plasma levels slightly higher than those achieved at 1 h with doses of 0.1 to 0.2 mg g-1 in mice. Tumour radiosensitisation with carbogen alone, and with carbogen combined with varying doses of nicotinamide (0.05 to 0.5 mg g-1), was investigated using a 10-fraction in 5 days X-ray schedule. Relative to air-breathing mice, a statistically significant increase in sensitisation was observed with both a local tumour control and with an in vivo/in vitro excision assay (P < or = 0.007). With the local control assay, a trend was observed towards lower enhancement ratios (ERs) with decreasing nicotinamide dose (from 1.85 to 1.55); carbogen alone was almost as effective as when combined with 0.1 mg g-1 of nicotinamide. With the excision assay, ERs for carbogen combined with nicotinamide increased with decreased levels of cell survival. At a surviving fraction of 0.02, enhancement ratios of 1.39-1.48 were obtained for carbogen plus 0.1 to 0.3 mg g-1 of nicotinamide. These were lower than those seen with the two higher doses of 0.4 to 0.5 mg g-1 (ERs = 1.63-1.69).
Adenocarcinoma↗
Monoclonal antibodies to apolipoprotein AI: generation and characterization.
BALB/c mice were immunized with apolipoprotein (apo AI)--high density lipoprotein (HDL) conjugate. By polyethylene glycol-induced fusion of isolated spleen cells with the myeloma cell line P3 X63 Ag8 6.5.3, three different hybridomas were obtained and characterized. Two of them were found to secrete antibodies of the IgG2a subclass, whereas the third produced antibodies of the IgG1 type. Binding capacities to 125I-apo AI and 125I-HDL were higher than 90% in all cases. The isolated antibodies recognize independent epitopes on the apo AI molecule and bind isolated HDL and serum-HDL with different affinities.
Animals↗
Metabolized medium from the X63-m-IL2 cell line as a supplement to enhance immune response during in vitro immunizations.
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Animals↗
[Biochemical markers of bone remodeling and bone density in healthy postmenopausal women].
The aim of this study was to study bone turnover and density in postmenopausal women. One hundred healthy postmenopausal women aged 45 to 86 years, in whom menopause occurred between 3 months and 33 years before and were not receiving medications that could alter bone metabolism, were studied. Measurements performed were serum alkaline phosphatases, urine hydroxyproline/creatinine and calcium/creatinine excretion ratios and lumbar spine and femoral bone densities. Mean urinary hydroxyproline/creatinine excretion ratio was 39.5 +/- 11.9 (over 45 in 26% of women) and calcium/creatinine ratio was 0.11 +/- 0.08 (over 0.12 in 29% of women). At least one of these measurements were increased in 39% of women and no relationship of these values with age or length of postmenopausal period was found. Alkaline phosphatases were elevated in 9.6% of women. Twenty six percent of women had lumbar spine osteopenia and 10% femoral neck osteopenia. There was an inverse relationship between the length of hypoestrogenism and bone density. It is concluded that more than one third of studied women had biochemical evidences of bone resorption and that these women had a higher frequency of osteopenia than the general population. A decrease in bone density and an increase in bone resorption indices identify women with higher risk of osteoporosis that could be benefitted with an opportune treatment.
Absorptiometry, Photon↗
[3 beta-hydroxysteroid dehydrogenase defect: frequency of presentation in a sample of Chilean hirsute women].
The defect of 3 beta hydroxysteroid dehydrogenase (3 beta HSD) is frequent among hirsute women and clearly dependent on the ethnic composition of the studied population. Our aim was to study the frequency of 3 beta HSD deficit in a group of Chilean hirsute women. Basal and post ACTH concentrations of cortisol, 17 hydroxyprogesterone and 17 hydroxypregnenolone were measured by RIA in 40 hirsute post puberal women and in 15 normal age matched female volunteers. Criteria for considering a 3 beta HDS deficit were 17 hydroxypregnenolone values and 17 hydroxypregnenolone/17 hydroxyprogesterone and 17 hydroxypregnenolone/cortisol ratios after ACTH stimulation over the 95% confidence intervals of normal women. Basal dehydroepiandrosterone sulphate and testosterone levels were also measured in hirsute women. All samples were obtained during the follicular phase of the menstrual cycle. ACTH stimulated hormone values and ratios were diagnostic for 3 beta HDS deficit in 7.5% of hirsute women. Basal testosterone was over 80 ng/dl in 47.5% and dehydroepiandrosterone sulphate over 3.9 micrograms/ml in 52.5% of these women. There was no correlation between dehydroepiandrosterone or testosterone values and ACTH stimulated hormone values. It is concluded that 3 beta HSD is frequent in hirsute women and that its diagnosis requires the determination of ACTH stimulated 17 hydroxypregnenolone values and 17 hydroxypregnenolone/17 hydroxyprogesterone ratio.
17-alpha-Hydroxypregnenolone↗
Renal damage in the mouse: repair kinetics at 2 and 7 Gy per fraction.
The kinetics of repair of radiation damage during the intervals between fixed X-ray dose fractions of 2 or 7 Gy has been measured in the kidneys of mice. Two-gray fractions were given as one pair per day for a total of 9 days, with intervals of 0 to 12 h between the two doses in each pair. Seven-gray fractions were given as a single pair, also with different interfraction intervals. Variable top-up doses of d(4)-Be neutrons were given as two fractions separated by 1 week, starting 1 day after the last X-ray dose in each of these schedules, to increase underlying renal damage to the level at which late functional injury could be measured by reduction in renal clearance and decrease in hematocrit to 45 weeks after irradiation. Two separate experiments were carried out, and when the data from the two studies were pooled, there was no difference at all in the repair rate between the schedules using 2- or 7-Gy fractions; values of repair half-time were within 1% of one another, demonstrating no dependence on dose per fraction. In both the individual experiments and the pooled data set, repair occurred single-exponentially at both 2 and 7 Gy per fraction and there was no evidence of a "slow" component. Analyzing the whole data set together gave a repair half-time of 1.29 +/- 0.16 h (95% confidence limits) and an alpha/beta ratio of 3.22 +/- 0.16 Gy.
Animals↗
Competitive enzyme inhibition immunoassay of apolipoprotein B based on monoclonal antibody.
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Apolipoproteins B↗
Evaluation of three rapid enzyme immunoassays and cell culture for detection of respiratory syncytial virus.
Three rapid enzyme immunoassay techniques for the detection of respiratory syncytial virus antigen (Becton Dickinson Directigen RSV, Abbott RSV Testpack and Abbott RSV EIA) and cell culture were evaluated in a total of 250 nasal washings. The sensitivity and specificity were 62% and 76% respectively for Directigen, 64% and 86% for RSV Testpack, and 76% and 81% for RSV EIA, taking cell culture as the reference method. Agreement between cell culture and EIA techniques was 79% (70 positive and 128 negative results). All three EIA techniques gave positive results in 69 samples (52 positive and 17 negative in the cell culture). In 121 samples all three EIA techniques gave negative results (103 negative and 18 positive in the cell culture). Using the cell culture technique 46 strains other than respiratory syncytial virus were isolated.
Animals↗
No increase in chromosome aberrations in lymphocytes from workers exposed to nitrogen fertilisers.
The putative genetic risk of people occupationally exposed to nitrogen fertilisers was studied using the structural chromosome aberration assay in peripheral blood lymphocytes. The exposed group included 23 subjects working at complex and mixed fertiliser plants. The percent of aberrant cells (Ab.C %) and break to cell ratio (B/C) were 0.95% and 0.01 respectively. The matched control group (20 subjects) was found to have 0.80% Ab.C and a B/C ratio of 0.0085. The results show a lack of detectable genetic damage in exposed people using this cytogenetic approach.
Adult↗
No increase in chromosome aberrations in workers from an oil catalytic cracking plant.
A study of structural chromosome aberration frequencies in blood lymphocytes was performed in a group of 20 oil catalytic cracking unit workers and in 26 subjects belonging to the office staff of an oil refining plant, as well as in 35 matched controls. Subjects in the latter group were of the same sex (males) and similar age as the exposed group, and had similar smoking habits. Benzo[a]pyrene levels in workplace air samples were also determined. The cytogenetic analysis failed to show any differences between the exposed and control groups. A slight increase in benzo[a]pyrene level above the Cuban national standard of 1 ng/m3 was found during the air sample analysis in the oil catalytic cracking unit.
Adult↗
Pharmacokinetics of nicotinamide and its effect on blood pressure, pulse and body temperature in normal human volunteers.
The pharmacokinetics of nicotinamide were studied in four human volunteers after oral doses of 1-6 g. Plasma concentrations and clearance rates of the vitamin were found to be dose-dependent, with a half-life of approximately 7-9 h for the two highest doses administered (4 and 6 g), approximately 4 h with 2 g and approximately 1.5 h with a 1-g dose. Peak concentrations ranged from 0.7 to 1.1 mumol.ml-1 after a 6-g dose. The time to reach peak plasma concentration was dose independent with a broad range from 0.73 to 3 h. In this study, nicotinamide had no detectable effect on blood pressure, pulse or body temperature.
Administration, Oral↗
Extrapolations from laboratory and preclinical studies for the use of carbogen and nicotinamide in radiotherapy.
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Animals↗