Biomedical subjects
C Torres
Publications and source records attributed to C Torres.
Synergistic activity of tobramycin-netilmicin against Enterococcus faecalis producing 6'-aminoglycoside-acetyltransferase, 2''-aminoglycoside-phosphotransferase enzyme.
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High-level penicillin resistance and penicillin-gentamicin synergy in Enterococcus faecium.
Thirty-seven Enterococcus faecium strains with different levels of penicillin susceptibility were studied in time-kill experiments with a fixed concentration (5 micrograms/ml) of gentamicin combined with different penicillin concentrations (6 to 600 micrograms/ml). Synergy was defined as a relative decrease in counts of greater than 2 log10 CFU per milliliter after 24 h of incubation when the combination of the antibiotics was compared with its most active component alone. The minimal synergistic penicillin concentrations found were 6 micrograms/ml for 16 of 16 strains for which penicillin MICs were < or = 25 micrograms/ml, 20 to 100 micrograms/ml for 14 of 17 strains for which penicillin MICs were 50 to 200 micrograms/ml, and 200 to 500 micrograms/ml for 4 of 4 strains for which MICs penicillin were > 200 micrograms/ml. Penicillin-gentamicin synergy was observed even in high-level penicillin-resistant E. faecium strains at penicillin concentrations close to one-half the penicillin MIC. The possibility of treating infections caused by high-level penicillin-resistant E. faecium strains with penicillin-gentamicin combinations in particular cases may depend on the penicillin levels attainable in vivo.
[Cholinergic action of Bay K-8644 on the rat heart sinus node automaticity].
The actions of different concentrations of a dihydropyridine agonist (Bay K-8644) on rat heart sinus node automaticity and their interactions with atropine, were studied. The experiments were performed using a portion of the right atrium that contained the sinus node, perfused with Tyrode's solution at 37 degrees C and registering the action potentials with intracellular microelectrodes (Ag-KCL). The series of Bay K with or without atropine were perfused during 10 min. Atropine, 1 x 10(-5) M, did not change sinus frequency after 30 min of perfusion (237 +/- 6 to 229 +/- 7 action potentials/min; n = 24). Bay K, 2.8 x 10(-8) M (10 ug/L) did not change sinus frequency (240 +/- 9 to 246 +/- 12; n = 8, but in the presence of atropine, caused an increment (225 +/- 7 to 256 +/- 12 p < 0.05). Bay K, 7 x 10(-8) M (25 ug/L) and 1.4 x 10(-7) M (50 ug/L, caused an increase in sinus frequency (237 +/- 5 to 279 +/- 15; n = 9 p < 0.05 and 254 +/- 6 to 291 +/- 6; n = 6 p < 0.05 respectively) that occurred sooner in the presence of atropine. It is concluded that Bay-K has a cholinergic effect that interferes with its positive chronotropic action, specially at low concentrations.
Genotoxicity of four herbicides in the Drosophila wing spot test.
The herbicides alachlor, atrazine, maleic hydrazide and paraquat were evaluated for genotoxicity in the Drosophila melanogaster wing spot test. Third-instar larvae trans-heterozygous for two recessive mutations of wing trichomes, multiple wing hairs (mwh) and flare (flr3), were treated by chronic feeding with different concentrations of the four herbicides. Feeding ended with pupation of the surviving larvae. The genotoxic effects were determined from the appearance of clones of cells with mwh, flr3 or mwh-flr3 phenotypes. Exposure to maleic hydrazide resulted in a significant increase in the frequency of the three categories of spots recorded (small single, large single and twin spots) in a dose-related fashion. Exposure to alachlor induced significant increases in both small and total spots at the four concentrations assayed and in the frequency of twin spots at the highest concentration tested (10 mM). Atrazine and paraquat also induced significant increases in both small and total spots at three of the four concentrations tested, without indication of a direct dose-effect relationship.
Germinal and somatic mutation induction in Drosophila after treatment of larvae with tritiated water.
The present study was carried out to evaluate the mutagenicity of tritium, administered as tritiated water, in Drosophila melanogaster. Larvae were fed on tritium-treated medium during their development. Germinal and somatic mutation induction was detected by means of the sex-linked recessive lethal and the wing spot tests, respectively. Our results show that beta-radiation from tritium is able to induce significant increases in the frequency of both germinal and somatic mutations.
Self-directed work teams.
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Shock in a woman with chronic pain.
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Role of nucleus basalis in cholinergic control of cortical blood flow.
The present investigation was designed to determine the effect of lesions localized to the nucleus basalis/substantia innominata (NB) on resting and cholinergically activated regional cerebral cortical blood flow (rCBF). Ibotenic acid (10 micrograms) was infused locally at 1 mm caudal to bregma, 3 mm lateral to the midline, and 8 mm below the cortical surface. Effectiveness of lesions was demonstrated by histological verification of lesion sites and determination of choline acetyltransferase activity in cerebral cortex homogenates. rCBF was measured with the autoradiographic iodo-14C-antipyrine technique. Resting rCBF was similar in the hemisphere that received the NB lesion and in the contralateral (intact) side in all regions examined. Physostigmine intravenous infusion (3.3 micrograms.kg-1.min-1) enhanced rCBF in frontal, parietal, occipital, and temporal cortex. The increase was symmetrical, however, indicating inability of NB lesion to affect this phenomenon. It is concluded that the cortical cholinergic afferents originating in the NB are not involved in the control of rCBF.
Mortality prediction models in intensive care: acute physiology and chronic health evaluation II and mortality prediction model compared.
OBJECTIVE: To compare the Acute Physiology and Chronic Health Evaluation (APACHE II) score with the Mortality Prediction Model (MPM). DESIGN: A prospective study. SETTING: A nine-bed ICU in a 300-bed, nonteaching secondary hospital. PATIENTS: Three hundred thirty-two consecutive, unselected adults. MEASUREMENTS AND MAIN RESULTS: We found a good correlation between APACHE II and MPM; their performance expressed as area under the receiver operating characteristics curve was nearly the same. Goodness-of-fit between observed and expected occurrences was better for APACHE II than for admission MPM, which overestimated deaths. Because we evaluate patients early, often in the Emergency Department, we felt that a "lead-time bias" could explain this discrepancy. Reevaluation after initial stabilization improved the performance of the MPM model to the level of APACHE II. CONCLUSIONS: Our investigation indicates that both APACHE II and MPM are good predictors of hospital outcome in our population, but the level of intensive care services received before conventional ICU admission modifies accuracy of predictive models. In any study of outcome using comparative studies of classification systems, confounding biases should be measured.
Obstetric care of chemically dependent women requires more than 'doctor stuff'.
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IL-1, IL-2 and IFN-gamma production by Theiler's virus-induced encephalomyelitic SJL/J mice.
Interleukins have been postulated to exert an important modulatory and recruiting role in the Theiler's murine encephalomyelitis virus (TMEV)-induced demyelination of the central nervous system (CNS) in SJL/J mice. Using bio- and radioimmunoassays, we have detected and quantified some of the interleukins suspected to play a role in this immune-mediated process. The interleukins 1 and 2 (IL-1, IL-2) and interferon-gamma (IFN-gamma) have been measured in homogenates from the CNS and sera from infected animals, as well as in supernatants from antigen-specific in vitro-stimulated spleen and meningeal cells. IL-1 was detected both in CNS tissue homogenates (approximately 20-40 fmol/ml) and in splenic cultures (200 U/ml). IL-2 was detected only after TMEV-specific antigenic stimulation in spleen cultures (approximately 120 U/ml). In vitro, IL-2 and IL-1 synthesis appear in a dose- and time-dependent manner. IFN-gamma could not be found in any case. The precise nature of IL-1 and IL-2 activity was further assessed by HPLC. The above results strongly indicate the presence of functionally active macrophages in the CNS infiltrates of cells triggering this autoaggressive immune process. In addition, we propose a central role for IL-1 in augmenting the intracerebral immune response leading to the inflammatory demyelination induced by TMEV.
[Malignant Mediterranean boutonneuse fever. Septic shock of unknown origin?].
Mediterranean Botonous Fever (MBF) is an infectious disease which provokes multisystemic vasculitis due to endothelial proliferation of rickettsia conorii. Its incidence, in our environment, has greatly increased during the last years being endemic in many large cities and their surrounding suburbs. In some cases its evolution is specially malignant resulting in septic shock, adult respiratory distress syndrome, and multiorgan failure. The purpose of this communication is to present a new case of malignant MBF with a bad evolution factor which has not been previously referred to, which is the persistence of vector ticks in the inoculation spot.
The value of early third-trimester maternal serum alpha-fetoprotein determination.
The value of determination of maternal serum of alpha-fetoprotein (MSAFP) concentration in the second trimester is well established. In addition to open neural tube defects, pregnancies associated with elevated second-trimester MSAFP have been shown to be at increased risk for a variety of problems, including low birth weight, preterm delivery, and pregnancy-induced hypertension (PIH). We evaluated the potential usefulness of MSAFP in the early third trimester. MSAFP concentration was determined in over 200 women at the time of glucose screening. Results were analysed with regard to gestational age at sampling, maternal weight, race, diabetes, and presence of twins. MSAFP was twice as high in twin gestation, but not affected by race or the presence of diabetes. In contrast to levels in early gestation, third-trimester MSAFP does not appear to be predictive of preterm delivery, low birth weight, or PIH.
Potential prenatal predictions of Down syndrome: a statistical analysis.
To determine the feasibility of combining several screening tests for the prenatal detection of Down syndrome, we evaluated the potential relationship among three proposed predictors. We determined the concentration of chorionic gonadotropin in frozen serum samples from women of known maternal age and weight, fetal biparietal diameter, and femur length, and alpha-fetoprotein concentration. When corrected for gestational age and maternal weight, the potential predictors were independent, except for a slight correlation (r = 0.10) between maternal serum alpha-fetoprotein and maternal serum human chorionic gonadotropin. Both maternal serum human chorionic gonadotropin and biparietal diameter/femur length demonstrated an approximately log-normal distribution similar to maternal serum alpha-fetoprotein. Therefore it is scientifically sound to use any or all of these variables in combination for the identification of pregnancies at increased risk for Down syndrome.
Viral lower respiratory tract infections in Filipino children.
Viral causes of acute lower respiratory tract infection were studied prospectively between 15 June and 31 October 1984 in 312 Filipino children less than 5 years old living in periurban slums and middle-class housing. The cause was based on viral antigen detection, virus isolation, and antibody assays. There were 131 children (41.2%) who were admitted to the hospital, and 150 (47%) had an infiltrate on chest radiograph. A total of 198 viral infections were confirmed in 162 patients (51.9%), 42.3% with single viral infection and 9.6% with mixed (two or more) infection. The infections were measles (21.4%), influenza A (15.9%), parainfluenza types 1, 2, and 3 (8.8%), respiratory syncytial virus (7.1%), influenza B (5.8%), enteroviruses (5.1%), adenoviruses (3.9%), herpes simplex virus (1.6%), and cytomegalovirus (1.3%). Viral infections other than measles were seen in 39.7% of the cases. The presence of viral infection correlated with better nutritional status. Influenza A or B diagnosis was associated with mild forms of acute respiratory tract infection, measles and a preceding rash with severe disease.
Theiler's murine encephalomyelitis virus-binding activity on neural and non-neural cell lines and tissues.
Three categories of cell lines are described with respect to their activity in binding Theiler's murine encephalomyelitis virus (TMEV). High, medium and low densities of viral receptors can be detected on cell lines from different species and origins by using an immunological binding assay. Nevertheless, TMEV acts as a fastidious virus that only infects a few cell types productively. No correlation between virion binding and degree of permissiveness to infection could be detected. The presence of viral receptors in both susceptible and resistant strains of mice seemed to have a widespread tissue distribution, the thymus being an exception. When primary cerebral cultures, enriched in neurons, astrocytes or oligodendrocytes, were checked in the immunological assay, a higher density of viral receptors was detected in the neuronal population. The number of virus-binding sites in the BHK-21 cell line is reported here to be 5 x 10(3) per cell; approximately 15 x 10(3) and 2.5 x 10(3) are the estimates of binding sites per cultured neuron and macroglial cell, respectively.
In vitro processing at the 3'-terminal region of pre-18S rRNA by a nucleolar endoribonuclease.
In an investigation of the possible involvement of a highly purified nucleolar endoribonuclease in processing of pre-rRNA at the 3' end of the 18S rRNA sequence, an in vitro synthesized pre-18S rRNA transcript containing the 3' end region of 18S rRNA and the 5' region of the first internal transcribed spacer (ITS1) was used as a substrate for the enzyme. Cleavages generated by the nucleolar RNase were localized by S1 nuclease protection analysis and by the direct release of labeled rRNA products. Precise determination of the specificity of cleavage was achieved by RNA sequence analysis with end-labeled rRNA transcripts. These data demonstrated that the purified nucleolar RNase cleaved the pre-18S rRNA transcript at three specific sites relative to the 3' region of 18S rRNA. The first two sites included the mature 3'-end 18S rRNA sequence and a site approximately 55 nucleotides downstream of the 3'-end 18S rRNA sequence, both of which corresponded directly to recent results (Raziuddin, R. D. Little, T. Labella, and D. Schlessinger, Mol. Cell. Biol. 9:1667-1671, 1989) obtained with transfected mouse rDNA in hamster cells. The other cleavage occurred approximately 35 nucleotides upstream from the mature 3' end in the 18S rRNA sequence. The results from this study mimic the results obtained from in vivo studies for processing in the 3' region of pre-18S rRNA, supporting the proposed involvement of this nucleolar endoribonuclease in rRNA maturation.