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Biomedical subjects

M L Martínez

Publications and source records attributed to M L Martínez.

At least 19 recordsLinked to original sources
PubMed2001

Right ventricular ischemia in patients with primary pulmonary hypertension.

OBJECTIVES: The goal of this study was to determine whether right ventricular (RV) ischemia is a contributory factor in the development of RV dysfunction in patients with primary pulmonary hypertension (PPH). BACKGROUND: Patients with advanced PPH develop RV dysfunction, characterized by a decreased cardiac output, increased right atrial pressure (RAP) and/or elevated RV end-diastolic pressure, which progresses to heart failure and death. The cause of this dysfunction is unknown. Right ventricular ischemia may play a role in its development. METHODS: From 1992 to 1999, a prospective study involving 23 patients with PPH at the Instituto Nacional de Cardiologia "Ignacio Chavez" (Mexico City, Mexico) was undertaken. These patients were evaluated clinically and further studied by echocardiography, right heart catheterization and stress myocardial scintigraphy using technetium 99m sestamibi. RESULTS: Nine patients of 23 were found to have scintigraphic images consistent with RV ischemia. Significant correlation was found between RV ischemia obtained through myocardial perfusion scintigraphy and elevation of RV end-diastolic pressure (p < 0.001), elevation of RAP (p < 0.037) and a decrease in mixed venous oxygen saturation (p < 0.0001). No other clinical or hemodynamic variables showed a significant correlation with RV ischemia. CONCLUSIONS: A direct correlation exists between RV ischemia, as determined by myocardial scintigraphy, and hemodynamic alterations suggestive of RV dysfunction in patients with PPH.

Adult↗
PubMed2000

Purification and biological characterization of N-acetyl beta-D glucosaminidase from Bufo arenarum spermatozoa.

Fertilization in Bufo arenarum requires the sperm to penetrate the egg envelopes. The incubation of isolated vitelline envelopes with sperm induces the acrosome reaction, releasing proteases and glycosidases to the media. In the present work N-acetyl-beta-D-glucosaminidase, beta-D-galactosidase, beta-D-glucosidase, alpha-D-mannosidase, alpha-L-fucosidase, and alpha-D-glucosidase activities are measured in spermatozoa. N-acetyl-beta-D-glucosaminidase is the major sperm glycosidase activity assayed. However, N-acetyl-beta-D-galactosamine show competitive inhibitory effect. The glycosidase pH optimum is 3.5 being inhibited at pHs higher than 7.5. In our study, N-acetyl-beta-D-glucosaminidase is the only glycosidase that in vitro binds to vitelline envelopes in conditions that resemble natural fertilization media. The isolation of the active enzyme will allow studies of its role in fertilization. The enzyme has been purified in a two-step procedure. After native gel electrophoresis, the activity-stained band was cut out and the eluted enzyme was finally subjected to ConA-sepharose chromatography. In SDS-PAGE, the denatured enzyme migrates as a single band with a molecular mass of 45 kDa. Furthermore, analysis by size-exclusion on HPLC showed a peak of activity at around 45 kDa. Preliminary localization studies showed higher relative activity in the acrosomal content. In addition, 10% of the N-acetyl-beta-D-glucosaminidase activity was associated with the reacted sperm. By in vitro fertilization assay, it was observed that the inhibition of the enzyme results in the inhibition of fertilization. This last study shows that N-acetyl-beta-D-glucosaminidase plays an important role in toad fertilization.

Acetylglucosaminidase↗
PubMed2000

Methoxamine inhibits transient outward potassium current through alpha1A-adrenoceptors in rat ventricular myocytes.

alpha1-Adrenoceptor agonists are known to reduce transient outward potassium current (I(to)) in the heart. The aim of this study was to analyze the effect of methoxamine (mtx) on I(to) and to elucidate which adrenoceptor subtype was involved in this effect. We used the whole-cell configuration of the patch-clamp technique to record I(to). Our experiments confirm that mtx induces a dose-dependent decrease of I(to) that is characterized by an acceleration of time to peak (3.5 +/- 0.2 and 2.3 +/- 0.3 ms for control and mtx, respectively), and a decrease in both inactivation time constants (T(fast) was reduced from 20.8 +/-2.6 to 14.9 +/- 1.1 ms, and tau(slow) was reduced from 138 +/- 32.1 to 114 +/- 28.7 ms; n = 7). All these effects were antagonized by prazosin and the alpha1A-antagonist 5-methylurapidil but not by the irreversible alpha1B-antagonist chloroethylclonidine. These data indicate that stimulation of alpha1A-adrenoceptor subtype is involved in the methoxamine-induced reduction of I(to) in rat ventricular myocytes.

Adrenergic alpha-Agonists↗
PubMed1999

Expression of T-type Ca(2+) channels in ventricular cells from hypertrophied rat hearts.

In this study we examined the existence of T-type Ca(2+) current in ventricular myocytes isolated from rats with pressure-overload hypertrophy. The whole-cell clamp technique was used to record Ca(2+) currents in enzymatically dissociated ventricular cells. T- and L-type Ca(2+) currents were separated by applying voltage steps to different test potentials from a holding potential of -80 mV and -50 mV. T-type Ca(2+) current was defined as the difference between the currents from the two holding potentials. Ventricular myocytes from sham-operated rats showed only L-type Ca(2+) current (maximal density -13.9+/-1.3 pA/pF n=17), whereas ventricular myocytes isolated from rats with aortic stenosis showed both L- and T-type Ca(2+) currents. The average values of T- and L-type Ca(2+) current density were -4.8+/-0.4 pA/pF and -12.4+/-0.9 pA/pF (n=32), respectively. T-type Ca(2+) current was distinguished from L-type Ca(2+) current by its voltage dependence, its kinetics and by its strong blockade by nickel 50 microM. In conclusion, we have demonstrated that hypertrophied ventricular rat cells express T-type Ca(2+) channels and this finding strongly supports a role for this channel in regulating growth processes in cardiac tissue.

Animals↗
PubMed1999

Patients who attempted suicide and failed to attend mental health centres.

Different studies report non-attendance to treatment of between 20 to 70% of patients after a suicide attempt. However, few studies have analyzed the characteristics of this non-attending population. To determine therefore the characteristics or profile of individuals who do not attend outpatient centres to which they are referred after a suicide attempt, we performed this study. A total of 232 patients who had attended the Emergency Department of our general hospital were interviewed. Instruments used included the suicide risk scale, the violent behaviour scale, the impulsivity scale, the hopelessness scale, and the Beck's depression scale. Seventy-three percent of the sample did not attend the mental health centre to which they had been referred. In comparison to the attending group, the non-attending group had the following characteristics: unmarried, residing in an urban area, took less precautions not to be discovered, were more critical of the attempt, and the purpose of the attempt was to resolve a conflict. Our data emphasize the importance of social and interpersonal aspects in determining the nature of the psychiatric care required by these types of patients.

Adult↗
PubMed1999

Modulation of adrenergic receptors during left ventricular hypertrophy development and after regression by captopril.

The objective of this study was to analyze adrenergic receptors during cardiac hypertrophy development, after establishment of cardiac hypertrophy and after regression of cardiac hypertrophy by an angiotensin-converting enzyme inhibitor. Left ventricular hypertrophy (LVH) was induced by abdominal aortic stenosis. After surgery, plasma norepinephrine concentrations (PNE) and left ventricular adrenergic receptors from rat hearts subjected to aortic stenosis were assessed during cardiac hypertrophy development (at 3, 7, 15, and 30 days of aortic stenosis), once cardiac hypertrophy had been established (7 and 14 weeks after the stenosis) and after regression of cardiac hypertrophy by an antihypertensive dose (200 mg/kg/day) of captopril. The presence of LVH was observed from day 7 after stenosis. PNE had significantly increased after 15 days but returned to control values 30 days after surgery. The density of alpha1-adrenoceptors was found to decrease with development of hypertrophy. Once hypertrophy had been established, 7 weeks from stenosis, PNE was not different from control; however, the density of alpha1-adrenoceptors continued to diminish, whereas PNE and the density of beta-adrenoceptors were no different from control values. Fourteen weeks after stenosis, a significant decrease in PNE was recorded, and no change in alpha1- but an increase in beta-adrenoceptors was observed. LVH was reversed by treatment with captopril; PNE was similar in control and stenosed treated animals. The density of alpha1-adrenoceptors was decreased when compared with control animals, and no change in the density of beta-adrenoceptors was observed with treatment. In conclusion, a decrease of alpha1-adrenoceptors was associated with LVH development and earlier stages of established cardiac hypertrophy. Later stages of established cardiac hypertrophy were characterized by no change in alpha1- and an increase in beta-adrenoceptors. Treatment with captopril induced LVH regression and decreased the number of alpha1-adrenoceptors without any change in beta-adrenoceptors.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1998

[Invasive fungal infections in patients with blood disorders].

BACKGROUND: Invasive fungal infections (IFI) are severe infectious complications frequently observed in patients with hematological disorders. The aims of this study were to analyse the characteristics of this particular type of infection in a large series of a single institution and to determine the factors associated with the outcome and therapeutic response. PATIENTS AND METHODS: This study reviews the clinical and microbiological features of 155 IFI occurred among 144 patients with hematologic disorders throughout a period of 17 years in a single institution. RESULTS: In 118 cases (82%) the diagnosis was acute leukemia. The main risk factors for developing IFI included a persistent and profound granulocytopenia, the use of broad-spectrum antibacterial agents, indwelling central venous catheters and the damage of normal host barriers following intensive cytotoxic chemotherapy. Candida (65 cases [44%]) and Aspergillus (38 cases [26%]) species were the most common fungal species isolated. An increasing number of IFI were caused by fungi previously considered as contaminants or harmless colonizers. The outcome of IFI was favourable in 78 cases (50%). The most important prognostic factors for the outcome of the IFI were the phase of cytotoxic chemotherapy (p = 0.005), the response of the underlying disease to the cytotoxic chemotherapy (p < 0.00001), and the recovery of neutropenia during the infection course (p < 0.00001). An earlier use of empirical antifungal therapy was also associated with a better outcome. CONCLUSIONS: In spite of earlier treatment and regardless the development of new antifungal agents, the prognosis of IFI in patients with hematological malignancies remains poor. The use of hematopoietic growth factors, through their impact in the duration and severity of neutropenia, may prove valuable the management of IFI in this setting.

Acute Disease↗
PubMed1997

Visceral leishmaniasis in patients infected with the human immunodeficiency virus.

The experience with 52 episodes of visceral leishmaniasis diagnosed in 43 patients is reported. The most common symptoms were fever (81%), splenomegaly (65%), hepatomegaly (63%), and pancytopenia (73%). In 79% of the patients, CD4+ cell counts were < 100 cells/mm3. Prior or simultaneous diagnosis of AIDS was made in 29 (67%) patients. Diagnosis was considered fortuitous in 19% of the episodes. In 27% of the episodes, the diagnosis was made on the basis of demonstration of parasites outside the reticuloendothelial system, chiefly blood (7 cases) and gastrointestinal mucosa (5 cases). Parasites were frequently observed or cultured from blood (22/37 episodes) or the digestive tract (8/9 episodes). High antimony doses were more effective than low doses in achieving clinical or parasitological cure (rate of cure, 80% vs. 40%, p = 0.11). Severe toxicity was observed in six (11.7%) of the 51 treated episodes. Severe AIDS-related diseases [odds ratio (OR) 10, p < 0.05] and CD4+ counts (OR 12, p < 0.05) were independent factors for early death. Prophylaxis with monthly pentamidine was not useful in reducing relapses of visceral leishmaniasis.

AIDS-Related Opportunistic Infections↗
PubMed1996

Disseminated Blastoschizomyces capitatus infection in acute myeloblastic leukaemia. Report of three cases.

Three new cases of Blastoschizomyces capitatus infection occurring in neutropenic patients with acute myeloblastic leukaemia are reported. B. capitatus was isolated from blood cultures in all patients. All three patients were treated with amphotericin B, but only one was cured from the infection. Our study confirms the emergence of B. capitatus as an opportunistic agent of disseminated fungal infection in leukaemic patients.

Adult↗
PubMed1996

Assessment of the acrosome reaction in Bufo arenarum spermatozoa by immunostaining: comparison with other methods.

The acrosome reaction in Bufo arenarum spermatozoa has been visualised only by electron microscopy. Different staining procedures for spermatozoa are described in the present study. By light microscopy the acrosomal status cannot be determined. In some reacted sperm, stained with Coomassie blue, a filament that could be the "perforatorium' was observed, as seen by electron microscopy. Several fluorescent lectins were used, but only FITC-PNA binds to acrosomal proteins. However, the fluorescence observed was weak. Indirect immunofluorescence, with antibodies raised against acrosomal matrix, showed different staining patterns between acrosome-reacted and intact spermatozoa. The technique is specific for evaluating acrosomal status in a large population of spermatozoa. Moreover, immunostaining, in contrast with lectin staining, can be carried out in the presence of glycoconjugates such as oocyte extracellular matrix without interference.

Acrosome↗
PubMed1996

[Gammagraphy with HMPAO-99mTc leukocytes in intestinal inflammatory disease].

The value of 99mTc-hexamethylpropyleneamine oxime (HMPAO) leukocyte images has been confirmed in patients with Inflammatory Bowel Disease. We performed 121 scintigraphic examination. The results were evaluated by radiologic and/or endoscopic examinations. The patients were divided into three subgroups: A) patients with active disease and less than 15 days of corticotherapy (n = 42). B) patients with active disease and more than 15 days of corticotherapy (n = 31). C) asymptomatic patients (n = 48). Over all sensitivity and specificity were 86% and 92.2% respectively. The sensitivity in subgroup A was 97.5% and 70% in the subgroup B. In the subgroup A the isotopic study showed the entire area of active inflammation in 95% (38/40) and colonoscopy in 32.5% (13/40). The leucocyte scanning showed clear pathologic activity in the ileum with a sensitivity of 86%. We conclude that 99mTc-leukocyte scintigraphy is the best method to assess the location of active inflammation in patients with less than 15 days of treatment. Scintigraphy was best in the assessment of active disease especially in Crohn's disease of the small bowel.

Adult↗
PubMed1994

[Posterior cortical dementia].

Two patients, aged 59 and 73 years, presented with the clinical syndrome of Posterior Cortical Dementia (PCD). Follow-up during 3 and 11 years confirmed the progressive nature of the disorder. Posterior cerebral impairment was seen on SPECT studies. Neuroimaging studies showed an early dilatation of the right occipital ventricular horn which predominated over the cortical atrophy. This kind of cerebral atrophy could identify a subset of PCD cases that may be unrelated to Alzheimer's disease.

Aged↗