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Biomedical subjects

M Trujillo

Publications and source records attributed to M Trujillo.

At least 55 records · Page 3Linked to original sources
PubMed1996

Heterologous expression and characterization of the bifunctional dihydrofolate reductase-thymidylate synthase enzyme of Toxoplasma gondii.

We have expressed catalytically active Toxoplasma gondii dihydrofolate-thymidylate synthase (DHFR-TS) and the individual TS and DHFR domains in Escherichia coli using the T7 promoter of pET-15b. DHFR-TS constituted approximately 10% of the total soluble cell protein and was purified using methotrexate-Sepharose chromatography to yield 10 mg of homogeneous DHFR-TS per liter of culture. The DHFR domain was recovered as insoluble inclusion bodies which could be unfolded and refolded to recover soluble, active enzyme. The TS domain was overexpressed as a soluble protein by growing the cells at 24 degrees C; this is the first report of the expression of an active TS domain from a bifunctional enzyme. The kcat and K(m) values for DHFR-TS are similar to those of other previously characterized protozoan DHFRs and TSs. The antimicrobial antifolates, TMP and Pyr, inhibit DHFR activity of the bifunctional protein in accord with their effects in crude enzyme preparations and in vivo systems. Kinetic parameters and Ki values for TMP and Pyr with the isolated DHFR domain were identical to the values for DHFR in the bifunctional enzyme. Evidence of kinetic channeling of the dihydrofolate product of TS to the DHFR domain in the bifunctional enzyme was obtained by kinetic and inhibition studies. Properties such as yield, stability, and activities of the recombinant T. gondii DHFR-TS provide clear advantages over other bifunctional DHFR-TSs as a model for future studies.

Animals↗
PubMed1996

Randomized comparison of differing periods of twice-a-day triple therapy for the eradication of Helicobacter pylori.

BACKGROUND: We assessed the efficacy, compliance, and tolerability of the twice-a-day triple therapy, amoxycillin, omeprazole, and clarithromycin, for Helicobacter pylori and studied the effect of treatment duration (7, 10 or 14 days) on these factors. METHODS: One-hundred and fifty subjects with H. pylori infection documented by 13C-urea breath test were randomly assigned to a 7, 10 or 14-day course of amoxycillin 1 g b.d., omeprazole 20 mg b.d. and clarithromycin 500 mg b.d. Subjects returned at the end of therapy for pill count and assessment of side-effects. Subjects returned for a repeat 13C-urea breath test 4 weeks after the end of therapy. RESULTS: Poor compliance (< 80% of medications taken) was seen in 0 subjects at 7 days, 6% at 10 days, and 10% at 14 days (P = 0.03 by chi 2 test for trend; difference for 7 vs. 14 days = 10%; 95% CI, -2% to 18%; P = 0.056). Intention-to-treat eradication rates were 86% at 7 days, 90% at 10 days and 92% at 14 days. Per-protocol eradication rates were 86% at 7 days, 91% at 10 days, and 95% at 14 days (P = 0.11; difference for 7 vs. 14 days = 9%; 95% CI, -2% to 21%; P = 0.17). CONCLUSIONS: One week of twice-a-day amoxycillin, omeprazole and clarithromycin is well tolerated and provides a good rate of H. pylori eradication. Increasing the duration of therapy decreases compliance but has the potential to modestly improve efficacy if the patient takes the full complement of medication.

Adult↗
PubMed1996

Cerebrospinal fluid values in the term neonate.

BACKGROUND: Cerebrospinal fluid (CSF) values in the noninfected neonate are not well-delineated. Studies analyzing these values are inconsistent in the criteria used to define the noninfected population. The purpose of our study was to examine CSF values in neonates in the first 30 days of life in whom infection was more thoroughly excluded than in previous reports. Stringent inclusion criteria defined the noninfected population, and the recently available polymerase chain reaction (PCR) for enteroviruses was used in addition to cultures to help exclude viral disease. Results were also stratified by age in weeks to evaluate for any variability that occurs in CSF values during the first month of life. METHODS: Neonates were selected from subjects enrolled in two studies on aseptic meningitis. Noninfected infants were identified by the following criteria: (1) atraumatic lumbar puncture (< or = 1000 red blood cells/mm3); (2) no antibiotic therapy before lumbar puncture; (3) sterile blood, CSF and urine bacterial cultures; (4) negative CSF viral culture; and (5) negative CSF PCR for enteroviruses. RESULTS: The mean +/- SD total CSF white blood cell count for 108 noninfected neonates was 7.3 +/- 14/mm3 (95% confidence interval 6.6 to 8.0/mm3) with a median of 4/mm3 and a range of 0 to 130/mm3. There were no significant differences in the mean CSF white blood cell counts among age categories. CONCLUSIONS: The application of stringent inclusion criteria and the use of the PCR yielded a population of infants that better represents the noninfected neonate than earlier reports. These values can be used for reference in evaluating the febrile or ill neonate.

Age Factors↗
PubMed1996

Prospective evaluation of the macrolide antibiotic dirithromycin for the treatment of Helicobacter pylori.

BACKGROUND: Macrolide antibiotics are active in vitro and in vivo against Helicobacter pylori. We assessed a newer macrolide, dirithromycin, for the treatment of H. pylori in two separate studies. METHODS: Volunteers with H. pylori infection (by 13C-urea breath test) were randomly assigned to 2-week treatment regimens. Study 1: dirithromycin 500 mg q.d.s., dirithromycin 500 mg q.d.s. plus omeprazole 40 mg q.d.s., or dirithromycin 500 mg q.d.s. plus metronidazole 500 mg t.d.s. Study 2: dirithromycin 500 mg q.d.s. plus omeprazole 20 mg b.d., dirithromycin 1000 mg q.d.s. plus omeprazole 20 mg b.d., or amoxycillin 500 mg q.d.s. plus omepirazole 20 mg b.d. Four weeks after the completion of therapy a repeat 13C-urea breath test was done to assess for cure. RESULTS: No patient taking dirithromycin alone (n = 6) or in combination with omeprazole (n = 26) achieved cure of their infection. Eradication of H. pylori was seen in one of seven patients taking dirithromycin plus metronidazole. Five of 10 patients taking omeprazole-amoxycillin dual therapy had their H. pylori infection cured (P = 0.0007 vs. patients taking dirithromycin plus omeprazole). Eleven (47%) of 32 patients taking dirithromycin alone or combined with omeprazole reported side-effects, but only two (6%) stopped therapy prematurely as a result of side-effects. CONCLUSION: No subject taking dirithromycin alone or in combination with omeprazole had their H. pylori infection cured. Dirithromycin, in the regimen used, shows little promise in the treatment of patients with H. pylori infection.

Adult↗
PubMed1996

Clindamycin therapy of experimental meningitis caused by penicillin- and cephalosporin-resistant Streptococcus pneumoniae.

Although penicillin resistance among Streptococcus pneumoniae strains is increasing in many areas, resistance to clindamycin remains low. In our well-characterized rabbit meningitis model, we conducted experiments to evaluate the bacteriologic efficacy of clindamycin after a penicillin- and cephalosporin-resistant S. pneumoniae strain was intracisternally inoculated. Animals received a loading intravenous dose of 30 mg of clindamycin per kg of body weight and then two doses of 20 mg/kg given 5 h apart. In addition to clindamycin, some animals received dexamethasone (DXM) with or without ceftriaxone. The concentrations of clindamycin in cerebrospinal fluid were from 8.9 to 12.8% of the concomitant concentrations in serum and were unaffected by DXM administration. Mean changes in CFU (log10 per milliliter) at 10 and 24 h were -3.7 and -6.1, respectively, for clindamycin-treated rabbits, -3.6 and -6.3 for clindamycin-DXM-treated rabbits, -3.9 and -5.8, respectively, for clindamycin-ceftriaxone-treated rabbits, and -5.0 and -6.7, respectively, for clindamycin-ceftriaxone-DXM-treated rabbits. By 24 h all but one of the cultures of cerebrospinal fluid (that from a clindamycin-DXM-treated rabbit) were sterile. Because of the potential risk for clindamycin-treated rabbits to develop macrolide-lincosamide resistance, we attempted, unsuccessfully, to induce clindamycin resistance in vitro in two S. pneumoniae strains. Although clindamycin therapy might be effective in selected patients with multiple-drug-resistant pneumococcal meningitis who have failed conventional treatments, clinical experience is necessary before it can be recommended.

Animals↗
PubMed1995

Kinetics of cytochrome c2+ oxidation by peroxynitrite: implications for superoxide measurements in nitric oxide-producing biological systems.

Cytochrome c3+ has been extensively used for the detection of superoxide produced in biological systems due to its fast superoxide-mediated reduction to cytochrome c2+. However, another biomolecule which is sometimes cogenerated with superoxide, nitric oxide, reacts with superoxide at almost diffusion-controlled rates (6.7 x 10(9) M-1 s-1), leading to the production of a highly oxidizing species, peroxynitrite anion (ONOO-). In this work we report that peroxynitrite readily oxidizes cytochrome c2+ to cytochrome c3+ in an ascorbate-reversible manner. The reaction between peroxynitrite and cytochrome c2+ occurs with a second-order rate constant of 2.3 x 10(5) M-1 s-1. The pH dependence of the apparent second-order rate constants as well as the effect of different scavengers indicated that peroxynitrous acid (ONOOH) in the ground state was the actual species responsible of cytochrome c2+ oxidation. The activation enthalpy, free energy, and entropy were +10.8 kcal mol-1, +11.8 kcal mol-1, and -3.15 cal mol-1 K-1, respectively, in agreement with the proposed reaction mechanism. Additionally, our results imply that when quantitating superoxide by the cytochrome c3+ reduction method, the existence of a simultaneous generation of nitric oxide and peroxynitrite may lead to an underestimation of the rates of superoxide production.

Cytochrome c Group↗
PubMed1995

Evaluation of CP-99,219, a new fluoroquinolone, for treatment of experimental penicillin- and cephalosporin-resistant pneumococcal meningitis.

CP-99,219 is a new fluoroquinolone that has excellent activity against gram-positive organisms including penicillin- and cephalosporin-resistant Streptococcus pneumoniae strains. In our well-established rabbit model of meningitis, we conducted experiments to determine the concentrations of CP-99,219 in cerebrospinal fluid (CSF) after intravenous administration and its ability to eradicate two penicillin-resistant pneumococcal isolates. The peak and trough concentrations of CP-99,219 in the CSF were from 19 to 25% of the concentrations simultaneously obtained in serum and were unaffected by concomitant dexamethasone administration. Compared with untreated (control) animals, three doses of CP-99,219 given 5 h apart significantly reduced the bacterial count in CSF by 5 to 6 log10 CFU at 10 h. Although 47% of the dexamethasone-treated animals and 18% of those not given the steroid had positive cultures at 24 h (14 h after administration of the last antibiotic dose), the mean bacterial counts did not change from those observed at 10 h. Additionally, only results for animals infected with one of the two pneumococcal strains appeared to be affected by concomitant dexamethasone therapy.

Animals↗
PubMed1994

Nitric oxide regulation of superoxide and peroxynitrite-dependent lipid peroxidation. Formation of novel nitrogen-containing oxidized lipid derivatives.

Superoxide (O2-.), nitric oxide (.NO), and their reaction product peroxynitrite (ONOO-) have all been shown to independently exert toxic target molecule reactions. Because these reactive species are often generated in excess during diverse inflammatory and other pathologic circumstances, we assessed the influence of .NO on membrane lipid peroxidation induced by O2-., H2O2, and .OH derived from xanthine oxidase (XO) and by ONOO-. Experimental conditions in lipid oxidation systems were adjusted to yield different rates of delivery of .NO, relative to rates of O2-. and H2O2 generation, by infusion of either .NO or via .NO released from S-nitroso-N-acetylpenicillamine or S-nitrosoglutathione. Peroxidation of phosphatidylcholine liposomes was assessed by formation of thiobarbituric acid-reactive products and by liquid chromatography-mass spectrometry. Liposomes exposed to XO-derived reactive species in the presence of .NO exhibited both stimulation and inhibition of lipid peroxidation, depending on the ratio of the rates of reactive oxygen species production and .NO introduction into reaction systems. Nitric oxide alone did not induce lipid peroxidation. Linolenic acid emulsions peroxidized by XO-derived reactive species showed similar dose-dependent regulation of lipid peroxidation by .NO. Mass spectral analysis of oxidation products showed formation of nitrito-, nitro-, nitrosoperoxo-, and/or nitrated lipid oxidation adducts, demonstrating that .NO serves as a potent terminator of radical chain propagation reactions. Electron spin resonance (ESR) analysis of incubation mixtures provided no evidence for formation of paramagnetic iron-lipid-nitric oxide complexes in reaction systems. Peroxynitrite-dependent lipid peroxidation, which predominantly occurs by metal-independent mechanisms, was also inhibited by .NO. Peroxynitrite-mediated benzoate hydroxylation was partially inhibited by .NO, inferring reaction between .NO and ONOOH. It is concluded that .NO can both stimulate O2-./H2O2/.OH-induced lipid oxidation and mediate oxidant-protective reactions in membranes at higher rates of .NO production, with the prooxidant versus antioxidant outcome critically dependent on relative concentrations of individual reactive species. Prooxidant reactions of .NO will occur after O2-. reaction with .NO to yield potent secondary oxidants such as ONOO- and the antioxidant effects of .NO a consequence of direct reaction with alkoxyl and peroxyl radical intermediates during lipid peroxidation, thus terminating lipid radical chain propagation reactions.

Hydroxyl Radical↗
PubMed1994

The processing pathway of prelamin A.

The conversion of mammalian prelamin A to mature lamin A proceeds through the removal of 18 amino acids from the carboxyl terminus. The initial step in this processing is the isoprenylation of a CAAX box cysteine. This proteolytic event is distinctive for prelamin A among the known prenylated mammalian proteins. Since the carboxyl terminus of prelamin A is removed during maturation, it is not obvious that this protein would undergo the two reactions subsequent to prenylation observed in other CAAX box proteins--the endoproteolytic removal of the carboxyl-terminal 3 amino acids and the subsequent methylation of the now carboxyl-terminal cysteine. To characterize the maturation of prelamin A further, we have developed a CHO-K1 cell line that possesses a dexamethasone-inducible human prelamin A against a genetic background of high mevalonate uptake. Utilizing this cell line in association with antibodies specific to the transgenic prelamin A, we have been able to demonstrate directly in vivo that prelamin A undergoes farnesylation and carboxymethylation prior to conversion to lamin A, as is the case for other prenylated proteins. We have demonstrated previously that in the absence of isoprenylation, conversion of prelamin A to lamin A is blocked, but that unprocessed prelamin A is transported to the nucleus where it can still undergo maturation. Consistent with the implications of these prior studies, we now demonstrate the presence of both subunits of farnesyl-protein transferase in the nucleus.

Amino Acid Sequence↗
PubMed1994

The development of health knowledge in low-income Mexican-American children.

Children growing up in poverty are at risk for various health problems. For low-income, Mexican-American children, these risks include obesity, diabetes, and accidental injuries, 3 conditions that can largely be prevented by healthy life-styles. Despite the potential for prevention through education leading to health-promoting behaviors, very little is known about the development of health knowledge in this population. The present study examined low-income, Mexican-American children's understanding of the relation between health behavior and health status in 3 areas: nutrition, hygiene, and safety. 79 children (41 boys, 38 girls) ages 4 to 8 years participated. Children's knowledge was assessed in a structured play situation conducted in a laboratory setting. Results revealed that children knew the least about the relation between food consumption and their health, and knew the most about beneficial and harmful practices in the areas of safety and hygiene. Age and gender differences were also significant, with girls and older children more likely to provide elaborate and complex rationales for their responses. Implications of the findings for understanding the role of cognitive development and experience in the development of health knowledge are considered.

Child↗
PubMed1991

The use of fetal echocardiography for predicting intrapartum fetal heart rate patterns in the post-term pregnancy.

One of the shortcomings of antepartum testing in the post-term pregnancy is that it does not identify the majority of fetuses who develop abnormal intrapartum fetal heart rate changes. The purpose of this study was to determine whether antenatal cardiovascular evaluation could aid in the identification of post-term fetuses at risk for intrapartum heart rate abnormalities. Seventy-five patients with a gestational age greater than 41 weeks underwent a non-stress test, amniotic fluid index and real-time assessment of the heart for the presence or absence of a pericardial effusion. M-mode measurements of the right ventricular inner dimension (RVID), left ventricular inner dimension (LVID), biventricular outer dimension (BVOD) and Doppler velocimetry of the umbilical artery (S/D) were performed. Group I (n = 32) had normal intrapartum heart rate tracings. Group II (n = 20) had abnormal intrapartum fetal heart rate tracings but did not undergo emergency delivery. Group III (n = 23) had abnormal intrapartum fetal heart rate tracings but underwent emergency delivery. When comparing Group I with Group II, the latter had significant differences for abnormal RVID, RVID/LVID ratio, and pericardial effusion. When comparing Groups I and III, there were significant differences for RVID, RVID/LVID ratio, pericardial effusion, BVOD, LVID and amniotic fluid index. Neither the non-stress test nor S/D predicted abnormal intrapartum fetal heart rate patterns. For prediction of abnormal intrapartum heart rate patterns, the sensitivities of the RVID (0.79), LVID (0.33), RVID/LVID ratio (0.72) and BVOD (0.63) were 1.7-4 times greater than the non-stress test (0.19) and the sensitivities of the RVID, RVID/LVID ratio and BVOD were 2 times greater than the amniotic fluid index (0.28). The positive (0.50-0.86) and negative (0.42-0.68) predictive values were similar for all groups. To predict emergency delivery associated with abnormal heart rate tracings, the sensitivities of the RVID (0.83), RVID/LVID ratio (0.70) and BVOD (0.65) were 2.5-3 times greater than the non-stress test (0.26) and 1.5 times greater than the amniotic fluid index (0.39). The positive (0.36-0.56) and negative (0.70-0.86) predictive values were similar. The presence of pericardial effusion had a higher sensitivity than the non-stress test and amniotic fluid index for predicting abnormal intrapartum heart rate patterns but not emergency delivery. Doppler velocimetry of the umbilical artery had a lower sensitivity than the non-stress test and amniotic fluid index for predicting intrapartum heart rate patterns as well as identifying the fetus needing emergency delivery. The results of this study would suggest that there is initially dilatation of the right ventricle which may be associated with abnormal intrapartum fetal heart rate patterns. However, when the left ventricle dilates, leading to cardiomegaly, there is a greater incidence of abnormal intrapartum fetal heart rate changes and associated emergency delivery. The amniotic fluid index appears to be a later finding for predicting abnormal intrapartum fetal heart rate changes.

Journal Article↗
PubMed1991

Brief psychotherapy of personality disorders.

Thirty-two patients with personality disorder diagnoses were randomly assigned to two treatment conditions that vary on several techniques of brief dynamic psychotherapy. Seventeen patients constituted a waiting list control group. The two brief psychotherapies showed significant improvement on target complaints, SCL-90, and Social Adjustment Scale-SR compared with the control subjects. The two therapy groups were similar in overall outcome but showed interesting differences on several subscale measures. Process measurements of videotaped sessions revealed significant variations in frequencies of therapist interventions across the two treatment conditions, which validated planned differences in the treatment techniques.

Cognitive Behavioral Therapy↗
PubMed1990

Change in patient affect/defense ratio from early to late sessions in brief psychotherapy.

The current study examined changes in the ratio of patients' affective and defensive behaviors during the course of brief psychodynamic psychotherapy. Treatments of 16 patients were videotaped. For each patient, four sessions were evaluated with a minute-by-minute coding system of process variables. When patients were grouped according to outcome scores, significant differences between the high outcome and the average-to-low outcome groups emerged. During the early phase of treatment, patients in both groups showed an average of one affective response per five defensive responses. By the late phase of treatment, the high outcome patients showed a marked shift to one affective response per two defensive responses, while the low outcome patients remained the same. An incidental finding was a negative correlation between good outcome and the ratio of defensive behavior to total patient activity.

Affect↗
PubMed1990

Treatment of paracoccidioidomycosis with itraconazole.

Forty-seven patients with active paracoccidioidomycosis were treated with itraconazole. The majority of the patients (45) had the chronic adult form of the disease while the remaining exhibited the juvenile form. All of the patients received itraconazole, 100 mg day-1, with the exception of two for whom the clinical condition necessitated a larger dose. The mean duration of therapy was 6 months, with a range of 3-24 months. Clinically, the skin and mucous membrane lesions as well as abdominal pain, auscultatory alterations and dysphonia improved markedly during treatment with a concomitant increase in weight. However, other symptoms (cough, expectoration and dyspnoea) persisted as sequelae in some cases. As expected adrenal insufficiency also persisted. The radiological lesions showed a gradual decrease of both scattered and confluent infiltrates, present in 67% of patients before, and in 13% at the end of treatment. On the other hand, fibrosis became more evident at the termination of therapy, increasing from 62% of patients at the beginning of therapy to 81% at the end. The mycological tests (direct examination and cultures) became negative during the first month of treatment in 42 patients (87%). A decline in specific antibody titres was observed in 72% of patients by the end of treatment. Evaluation of therapy by means of a scoring system indicated complete resolution of the disease in one patient (2%), marked improvement in 42 (89%) and minor improvement in four (8.5%); none of the patients showed a deterioration of their disease during therapy. Of fifteen patients who were followed up for 12 months post-therapy none showed clinical relapse during this period. The results of this study confirm the efficacy of itraconazole in the treatment of paracoccidioidomycosis.

Acute Disease↗
PubMed1990

[Vascular pathology of the temporal bone].

In a review of our cases over the last twenty years a series of patients from the E.N.T. clinic has been selected, all of which exhibit a clinical history of tinnitus and vertigo, and in some cases hearing loss. Neuroradiological exploration was able to show that a vascular aetiology was responsible in every case. In the literature concerning this type of otological pathology these procedures are seldom found. This study presents our cases and draws attention to the high risk which surgical intervention entails if there is an undiagnosed vascular mass in the middle ear.

Angiography↗