PubMed Health⌕ Search

Biomedical subjects

M Chávez

Publications and source records attributed to M Chávez.

At least 19 recordsLinked to original sources
PubMed2006

Neuropharmacological effects of an ethanol extract of the Magnolia dealbata Zucc. leaves in mice.

Magnolia dealbata Zucc. is considered to have tranquilizer and anticonvulsant properties in Mexican traditional medicine. In the present study we report the effects of a crude extract of Magnolia dealbata (30, 100 and 300 mg/kg) on mouse central nervous system (CNS). Pharmacological effects were tested on ambulatory activity, anti-anxiety response, sodium pentobarbital-induced hypnosis and pentylenetetrazole (PTZ)-induced seizures in comparison to honokiol, buspirone, ethosuximide and diazepam as corresponding reference drugs. No changes in spontaneous locomotor activity were produced posterior to Magnolia dealbata administration; however, a significant and dose-dependent diminution in the anxiety response was observed in experimental models such as plus-maze, head-dipping and exploratory rearing tests. Magnolia dealbata not only prolonged the time of sodium pentobarbital-induced hypnosis and delayed the onset of PTZ-induced mioclonus and clonus, but also hindered the presence of tonic seizures and avoided mortality. The hypnotic, anxiolytic and anticonvulsant effects obtained in these experiments support the hypothesis that Magnolia dealbata possesses CNS activity and reinforces the popular use in Mexican traditional medicine.

Animals↗
PubMed2004

A comparative study of the disc diffusion method with the broth microdilution and Etest methods for voriconazole susceptibility testing of Aspergillus spp.

OBJECTIVE: The activity of voriconazole against Aspergillus spp. (n = 77) was tested by the Etest, disc diffusion and the NCCLS M38-A methods. METHODS: Four Rhizomucor spp. isolates were included to study the suitability of the three susceptibility testing methods to detect isolates resistant to voriconazole. The disc diffusion method performed on Mueller-Hinton agar (Difco) supplemented with 2% glucose and Methylene Blue (0.5 mg/L) gave zone diameters with very clear border edges. RESULTS: The disc diffusion method showed excellent correlation with the Etest and the NCCLS methods. CONCLUSION: On the basis of our results, it appears that the disc diffusion test is a useful method for testing the activity of voriconazole against Aspergillus spp.

Antifungal Agents↗
PubMed2003

Comparison of Etest with modified broth microdilution method for testing susceptibility of Aspergillus spp. to voriconazole.

We compared the Etest with a broth microdilution method, performed according to a modified National Committee for Clinical Laboratory Standards guideline (M38-A), for determining the in vitro susceptibility of 77 isolates of Aspergillus spp. (26 A. fumigatus, 21 A. flavus, 10 A. terreus, 9 A. niger, 5 A. nidulellus, 4 A. glaucus, and 2 A. flavipes isolates). Overall, there was 92.2% agreement between both methods when Etest MICs were read at 24 h and 83.1% agreement when both methods were read at 48 h. When Etest MICs were read at 24 h, the agreement was >90% for all species tested except for A. fumigatus (84.6%). When Etest MICs were read at 48 h, the agreement ranged from 50 to 100%. The poorest agreement was seen with A. glaucus (50%) and A. fumigatus (65%). Where a discrepancy was observed between Etest and the reference method, the Etest MIC was generally higher. The Etest appears to be a suitable alternative procedure for testing the susceptibility of Aspergillus spp. to voriconazole.

Antifungal Agents↗
PubMed2001

XV-2c/KM-19 haplotype analysis of cystic fibrosis mutations in Mexican patients.

We analyzed 97 unrelated Mexican cystic fibrosis (CF) patients and their first-degree relatives to study the association of XV2C/TaqI/KM19/PstI haplotypes with CF mutations in this population. Haplotype phases could be established in 148 CF and 110 normal chromosomes, and haplotype distributions of normal and CF chromosomes differed significantly (P < 0.001). DeltaF508 and G542X mutations accounted for 56% of CF chromosomes and were found to be associated with haplotype B in 97.2% and 72.7% of chromosomes, respectively. The haplotype distribution of CF chromosomes carrying other rare and unknown mutations was similar to that of normal chromosomes (P > 0.05), haplotypes A and C being the most frequent. This is in accordance with the extensive heterogeneity and the spectrum of mutations reported in Mexican CF patients. We also report the haplotype distribution of all informative chromosomes bearing rare mutations; some were found to be associated with previously reported haplotypes, whereas others were found on different haplotypes. Recombination or recurrence of mutations may explain these different associations, although other intragenic markers must be used to better understand the origin and dispersion of CF mutations in our country. XK haplotype analysis allowed carrier detection among sibs in 24.3% of families, showing that this method may be useful for carrier detection in populations with high allelic heterogeneity.

Cystic Fibrosis↗
PubMed2001

Mycophenolate mofetil prevents salt-sensitive hypertension resulting from angiotensin II exposure.

BACKGROUND: Interstitial mononuclear cell infiltration is a feature of experimental models of salt-sensitive hypertension (SSHTN). Since several products of these cells are capable of modifying local vascular reactivity and sodium reabsorption, we investigated whether mycophenolate mofetil (MMF), a drug known to inhibit infiltration and proliferation of immune cells, would modify the SSHTN induced by angiotensin II (Ang II) infusion. METHODS: Sprague-Dawley rats received Ang II for two weeks using subcutaneous minipumps. A high-sodium (4% NaCl) diet was started on the third week and was maintained until the eighth week. MMF (30 mg/kg, N = 15), an immunosuppressive drug, or vehicle (N = 15) was given daily by gastric gavage during the initial three weeks. Sham-operated rats (N = 9) were used as controls. Body weight, blood pressure (tail-cuff plethysmography), and serum creatinine were determined weekly. Urinary malondialdehyde (MDA) excretion, renal histology, and immunohistology, including the presence of Ang II and superoxide-producing cells, were analyzed at the end of Ang II infusion and at eight weeks. RESULTS: MMF treatment did not modify hypertension induced during exogenous Ang II infusion, but prevented the subsequent SSHTN. Tubulointerstitial injury resulting from Ang II infusion was significantly reduced by MMF treatment, as were proliferative activity, T-cell infiltration and activation (interleukin-2 receptor expression), superoxide-producing cells, and urinary MDA excretion. Ang II-producing cells were present in the renal tubulointerstitium of rats with SSHTN (60 +/- 30 Ang II-positive cells/mm(2) at 8 weeks) and were reduced by two thirds in the MMF-treated group. Forty percent of lymphocytes infiltrating the tubulointerstitium stained positive for Ang II. The expression of Ang II receptors in the kidney was unmodified. CONCLUSIONS: SSHTN resulting from Ang II infusion is associated with infiltration and activation of immune cells that produce Ang II. MMF treatment reduces these features and prevents the development of SSHTN.

Angiotensin II↗
PubMed2001

Mycophenolate mofetil prevents salt-sensitive hypertension resulting from nitric oxide synthesis inhibition.

Recent studies have suggested that subtle microvascular and tubulointerstitial injury in the kidney can cause salt-sensitive hypertension. To test this hypothesis, we determined whether the mild renal disease induced by transient blockade of nitric oxide (NO) synthesis would result in salt-sensitive hypertension and whether prevention of the renal injury by coadministration of the immunosuppressive agent mycophenolate mofetil (MMF) would block the development of salt sensitivity. N(omega)-nitro-L-arginine-methyl ester (L-NAME; 70 mg/100 ml in the drinking water) was administered for 3 wk to rats with or without MMF (30 mg x kg(-1) x day(-1) by gastric gavage), followed by a 1-wk "washout" period in which the MMF was continued, which was followed in turn by placement on a high-salt (4% NaCl) diet for an additional 4 wk. Renal histology was examined at 3 and 8 wk, and blood pressure was measured serially. L-NAME treatment resulted in acute hypertension and the development of mild renal injury. During the washout period, blood pressure returned to normal, only to return to the hypertensive range on exposure of the animals to a high-salt diet. MMF treatment prevented the development of hypertension in response to a high-salt diet. This correlated with the ability of MMF to inhibit specific aspects of the renal injury, including the development of segmental glomerulosclerosis, the infiltration of T cells and ANG II-positive cells, and the thickening of afferent arterioles.

Animals↗
PubMed2001

[Prevalence of nutritional anemia in women of reproductive age. Costa Rica. National nutrition survey, 1996].

In 1996, The Ministry of Health and Inciensa conducted the latest National Nutrition Survey, to provide support and guidance to the national policies, plans and programs in the field of food and nutrition. The present paper reports the results for the prevalence of anemia estimated in a total of 884 women of reproductive age, in three areas: metropolitan area, other urban areas and rural areas. Anemia was determined through measurements of hemoglobin, plasma ferritin and plasma folates. In addition, hemoglobin patterns were determined by electrophoresis. The cutt-off points used were those recommended by the WHO. Anemia was present in 18.6% of the women. Severe to moderate deficiency of iron (< 12 ng/dl) and of folates (< 6 ng/dl) were found in 43.2 and 24.7% of women respectively, with statistically significant differences by area of residence. The magnitude of the problem for anemia can be classified as mild, for iron deficiency as severe, and for folate deficiency as moderate. In conclusion, Anemia represents a public health problem for Costa Rica that has remained constant throughout the last decade. In women of reproductive age, iron deficiency is the main cause of Anemia, followed by folates deficiency, and in a small percentage hemoglobinopathies. Intestinal parasites are not longer a mayor cause of Anemia. Prevalence of Anemia is influenced by place of residence, but not by age. In summary, despite the favorable health conditions present in Costa Rica, the prevalence of Anemia and of iron deficiency are similar to those of the Latin-American region. To improve this situation, public health interventions are necessary.

Adolescent↗
PubMed2000

Spectrum of CFTR mutations in Mexican cystic fibrosis patients: identification of five novel mutations (W1098C, 846delT, P750L, 4160insGGGG and 297-1G-->A).

We have analyzed 97 CF unrelated Mexican families for mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Our initial screening for 12 selected CFTR mutations led to mutation detection in 56.66% of the tested chromosomes. In patients with at least one unknown mutation after preliminary screening, an extensive analysis of the CFTR gene by single stranded conformation polymorphism (SSCP) or by multiplex heteroduplex (mHET) analysis was performed. A total of 34 different mutations representing 74.58% of the CF chromosomes were identified, including five novel CFTR mutations: W1098C, P750L, 846delT, 4160insGGGG and 297-1G-->A. The level of detection of the CF mutations in Mexico is still lower than that observed in other populations with a relatively low frequency of the deltaF508 mutation, mainly from southern Europe. The CFTR gene analysis described here clearly demonstrated the high heterogeneity of our CF population, which could be explained by the complex ethnic composition of the Mexican population, in particular by the strong impact of the genetic pool from southern European countries.

Cystic Fibrosis↗
PubMed2000

Comparison of the Etest and microdilution method for antifungal susceptibility testing of Cryptococcus neoformans to four antifungal agents.

We performed a prospective study to compare the Etest and the microdilution method (NCCLS guidelines) for determining the MICs of fluconazole, itraconazole, flucytosine and amphotericin B for 35 strains of Cryptococcus neoformans. For the microdilution method (MDM) RPMI 1640 medium with 2% glucose was used for fluconazole, itraconazole and flucytosine, and Antibiotic Medium 3 for amphotericin B. For the Etest, RPMI 1640 medium with 2% glucose and solidified with 1.5% agar was used for the four antifungal agents. Amphotericin B was also tested on Antibiotic Medium 3 solidified with 1.5% agar. Fluconazole and flucytosine MICs by the Etest showed good correlation with the broth MDM (81.1 and 89.2% agreement within two dilutions, respectively). With the tested population of itraconazole- and amphotericin B-susceptible isolates, the MIC agreement for itraconazole was 54%; amphotericin B showed the lowest agreement (8.1% on Antibiotic Medium 3 and 13.5% on RPMI).

Amphotericin B↗
PubMed2000

[Susceptibility to fluconazole and itraconazole in isolates of Candida spp. from HIV-positive and HIV-negative patients].

We studied the possible differences in the pattern of susceptibility to fluconazole and itraconazole in 393 isolates of Candida spp. from the oral cavity of HIV-positive patients and 102 isolates from HIV-negative patients with candidemia or candiduria. We used the broth microdilution method according to the NCCLS guidelines. We observed a decrease in the susceptibility to fluconazole in the group of HIV-positive patients in comparison to those who were HIV negative, especially in Candida albicans (MIC(90) 32 mg/l vs. 1 mg/l and Candida glabrata (MIC(90) 64 mg/l vs. 16 mg/l). Furthermore, we did not find any resistant strains in the HIV-negative group. For itraconazole, the MIC(90) was two dilutions greater in the HIV-positive patients, except for C. albicans, which had a much higher MIC(90) (4 mg/l vs. 0.12 mg/.). Therefore, the decrease in the susceptibility of Candida spp. in the HIV-positive patients must be taken into account when establishing a specific antifungal therapy.

Antifungal Agents↗
PubMed2000

[Susceptibility to fluconazole and itraconazole in isolates of Candida spp. from HIV-positive and HIV-negative patients]

We studied the possible differences in the pattern of susceptibility to fluconazole and itraconazole in 393 isolates of Candida spp. from the oral cavity of HIV-positive patients and 102 isolates from HIV-negative patients with candidemia or candiduria. We used the broth microdilution method according to the NCCLS guidelines. We observed a decrease in the susceptibility to fluconazole in the group of HIV-positive patients in comparison to those who were HIV negative, especially in Candida albicans (MIC(90) 32 mg/l vs. 1 mg/l and Candida glabrata (MIC(90) 64 mg/l vs. 16 mg/l). Furthermore, we did not find any resistant strains in the HIV-negative group. For itraconazole, the MIC(90) was two dilutions greater in the HIV-positive patients, except for C. albicans, which had a much higher MIC(90) (4 mg/l vs. 0.12 mg/.). Therefore, the decrease in the susceptibility of Candida spp. in the HIV-positive patients must be taken into account when establishing a specific antifungal therapy.

Journal Article↗
PubMed2000

[Incidence of genitourinary infection caused by Chlamydia trachomatis in a STD center calculated by direct antigen detection].

OBJECTIVE: Chlamydia trachomatis is one of the most common sexually transmitted agents which causes a wide spectrum of diseases including urethritis in men and endocervicitis in women. We analyzed patients with genitourinary C. trachomatis infections evaluating risk factors and the association with other sexually transmitted infections. MATERIAL AND METHODS: We processed 1,180 specimens from 913 patients (772 women and 141 men), attended at a Sexually Transmitted Diseases (STD) Center. The diagnostic of C. trachomatis infection was made by an enzyme-linked fluorescent immunoassay, Vidas Chlamydia test (bioMérieux). RESULTS: The incidence of C. trachomatis infection was 4.8% (57 cases) and was higher in women (70.1%) than in men (29.8%). The risk groups observed were: 26 prostitute, 7 contact with prostitute or risk partner, 5 homosexual, 5 promiscuous heterosexual and 14 without risk groups. Associated with this infection we observed other: 10 bacterial vaginosis, 8 Papillomavirus infection, 3 Trichomonas vaginalis infections, 2 Neisseria gonorrhoeae infections and 2 Candidiasis. The 53.4% of these patients didn't have any symptomatology at the consult moment. CONCLUSIONS: The control of patients with risk factors is important for the diagnostic of C. trachomatis and other sexually transmitted infections, because most of them were prostitutes and asymptomatic. Within men, homosexuality, contact with prostitute or risk partner were the practices with higher risk.

Antigens, Bacterial↗
PubMed2000

[Clinical characterization of 450 patients with cerebrovascular disease admitted to a public hospital during 1997].

BACKGROUND: In Chile, cerebrovascular diseases are the fifth cause of death among men and the third cause among women. AIM: To assess the clinical features and management of patients with cerebrovascular disease admitted to a public hospital during 1997. PATIENTS AND METHODS: A retrospective analysis of clinical records of patients discharged with a diagnosis of cerebrovascular disease. Those records in which there was discordance between the discharge diagnosis and the clinical picture were not considered in the analysis. RESULTS: Of the 563 discharges from the hospital with the diagnosis of cerebrovascular disease, 487 records were located and 450 were considered in the analysis. Fifty four percent of patients were male and ages ranged from 17 to 96 years old. Fifty-one percent of patients had an ischemic stroke, 34% a cerebral hemorrhage, 12% a subarachnoidal hemorrhage and 3% a transient ischemic attack. There was a history of hypertension in 64% patients and 20% had an adequate treatment. Eighteen percent were diabetics, 34% had a heart disease and 20% had a previous episode of stroke. Mean hospital stay was 6.3 days in the emergency room and 11 days in the neurology ward. Hospital infections appeared in 21% of patients (respiratory in 68% and urinary in 22%), lethality was 30.5% and a CAT scan was done in 94%. At the moment of admission, 10% of patients had an evolution of less than 2 hours, 27% had an evolution between 2 and 6 hours and nine cases were potential eligible for thrombolysis. CONCLUSION: This is a picture of the local features of patients with cerebrovascular diseases that can be used as a reference for future studies.

Adolescent↗
PubMed1999

In-vitro activity of voriconazole (UK-109,496), LY303366 and other antifungal agents against oral Candida spp. isolates from HIV-infected patients.

In this report we compare the activity of two new antifungal agents, voriconazole (UK-109,496) and LY303366 with the activities of other antifungals including fluconazole, itraconazole, 5-fluorocytosine (5FC) and amphotericin B against 219 oral Candida spp. isolates from HIV-infected patients. We used the broth microdilution method following the guidelines of the NCCLS. The in-vitro activity of voriconazole (UK-109,496) (MIC(90) 0.12 mg/L) and LY303366 (CMI(90) 0.25 mg/L) against clinical isolates of Candida spp. was excellent and comparable with that of amphotericin B (MIC(90) 0.5 mg/L), and better than those of fluconazole (MIC(90) > or = 64 mg/L), itraconazole (MIC(90) 4 mg/L) and 5FC (MIC(90) 1 mg/L).

AIDS-Related Opportunistic Infections↗
PubMed1998

Evaluation of the new API Candida system for identification of the most clinically important yeast species.

The API Candida system (bioMérieux) a new yeast identification system, was evaluated for its reliability in identifying 198 clinical yeast isolates in comparison with the API 20C system (bioMérieux) that was used as reference standard. The API Candida system correctly identified 91.4% and 71.7% of the isolates, with and without additional tests, respectively. The API Candida system identified 96.3% of common isolates studied, and 66.6% of uncommon isolates. We think that API Candida system is an easy and good yeast identification system and it could be used in a routine clinical microbiology laboratory.

Candida albicans↗
PubMed1998

[Activity of trovafloxacin and ten other antimicrobials against gram negative anaerobic bacilli].

As an increase in anaerobes resistant to a great variety of antimicrobials have been seen in the last few years, a search for new agents with activity against these microorganisms is needed. One of these agents is trovafloxacin. In our study, all strains were susceptible to imipenem, metronidazole, chloramphenicol and piperacillin/tazobactam. A total of 97% of the strains were inhibited with 2 mg/ml of trovafloxacin. The microorganisms Bacteroides fragilis and B. uniformis showed the least susceptibility against the antimicrobials studied, with a MIC90 for trovafloxacin of 1 and 2 mg/ml, respectively. Fusobacterium spp. were the most susceptible, with an MIC90 for trovafloxacin of 0.5 mg/ml. Trovafloxacin showed good activity against Gram-negative anaerobe rods, and could therefore be considered as an alternative in the treatment of the infections produced by these microorganisms.

Anti-Infective Agents↗
PubMed1996

Genetic analysis of the NAT2 and CYP2D6 polymorphisms in white patients with non-insulin-dependent diabetes mellitus.

The arylamine N-acetyltransferase (NAT2) polymorphism has been related to the risk of developing non-insulin-dependent diabetes mellitus (NIDDM). Several studies suggested an excess of rapid acetylators among NIDDM patients. This may be explained by an increased risk to develop NIDDM among subjects with the rapid acetylator capacity, or by changes in the acetylator status due to the disease or drug therapy. In order to elucidate this controversial topic, we have studied by a mutation-specific polymerase chain amplification (PCR) method the occurrence of seven point mutations at the coding region of the NAT2 gene in genomic DNA from 111 patients with NIDDM and 217 healthy controls. In addition, we have studied by the combined use of PCR and restriction fragment length polymorphism the occurrence of seven allelic variants of the CYP2D6 gene in the same subjects. In contrast to previous phenotyping studies, no relationship was found between NAT2 polymorphism and NIDDM or its complications such as nephropathy or neuropathy. The CYP2D6 genotype was similar between cases and controls. Our findings do not provide a genetic basis for any association of NIDDM and NAT2 polymorphism, suggesting that any excess of subjects with the rapid acetylator phenotype among patients with NIDDM should be secondary to the disease or concomitant drug therapy.

Acetylation↗