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Biomedical subjects

M Mendoza

Publications and source records attributed to M Mendoza.

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

Controlled trial of nimodipine in amyotrophic lateral sclerosis.

Calcium channel blocking drugs antagonize excitatory amino acid receptor activation, decrease calcium entry into damaged neurons, and might help to slow or reverse amyotrophic lateral sclerosis (ALS). We enrolled 87 patients with ALS in a randomized, placebo-controlled, prospective, double-blind crossover study of nimodipine therapy. Monthly measures of isometric muscle strength and respiratory function compared the effects of drug and placebo. No difference in adverse events occurred in placebo vs drug-treated patients, but diarrhoea, nausea, and lightheadedness were more common with nimodipine. There was no significant difference in the rate of decline of pulmonary function or limb strength during treatment with drug or placebo. Nimodipine was ineffective in slowing the progress of ALS.

Amyotrophic Lateral Sclerosis↗
PubMed1996

The use of tungsten carbide needle holders to remove intracanal objects.

The removal of metallic filling materials and posts is necessary before endodontic retreatment. Retreatment in such cases can require considerable time and effort. This article presents a technique to facilitate the removal of metallic obstructions from root canals using tungsten carbide needle holders. Clinical cases demonstrate the effectiveness of this technique.

Adult↗
PubMed1996

[Detection of anti-Treponema pallidum antibodies with colloidal gold immunoprobes].

BACKGROUND: The aim of this study was to evaluate the usefulness of colloidal gold probes widely used in histochemistry and electronic microscopy for the serologic diagnosis of syphilis. METHODS: One hundred eighty-nine sera which had been submitted to the traditional fluorescent trigenemic absorption (FTA-ABS) test and had later been tested with the new colloidal gold probe method (IAT-ABS). RESULTS: Out of a total of 103 positive samples by FTA-ABS all were positive when tested by gold immunoprobes (sensitivity 100%). Eighty-six samples which were negative by immunofluorescence were all negative by IAT-ABS (specificity 100%). CONCLUSIONS: The new method of colloidal gold probes with the current microscopy is useful for confirming serologic diagnosis of syphilis.

Adolescent↗
PubMed1994

Minimal incision palatopharyngoplasty. A preliminary report.

A new palatopharyngoplasty which allows good muscular reorientation as well as elongation of the soft palate with minimal morbidity and scarring has been developed, and 66 selected patients underwent the procedure during the period September 1989 to March 1993. The most important findings were reduced operative bleeding, good length and mobility of the soft palate, and minimal scarring. A total of seven fistulas (11%) developed. Twenty-three patients (mean age 6 years and 2 months at the time of operation) underwent nasopharyngoscopy and multiview videofluoroscopy; velopharyngeal insufficiency was evident in only four (17%). Dental casts were obtained in 14 patients (mean age at the time of the operation 1 year, 3 months) who were followed up for a maximum period of two years. No postoperative orthodontic treatment was required and the width and harmony of the dental arch were maintained in all cases.

Adolescent↗
PubMed1992

Characterization of Caramel Colour IV.

A large number of commercial Caramel Colour IV samples were characterized in order to assess the uniformity of the class and to provide data to be used in specifications development. Owing to the chemical and physical complexity of caramel colour it was not feasible to perform detailed analysis of all constituents for assessment of uniformity. Instead, selected parameters were evaluated and judgements were made with respect to compositional uniformity based on the similarities of these parameters among the various samples. As Caramel Colour IV is required by the food industry in a range of colour intensities, there must be a range of properties that differ from sample to sample, but that are sufficiently similar for the material to still be considered as part of the Caramel Colour IV class. Fractions as well as whole caramel were analysed using selected spectrophotometric, chromatographic and chemical techniques. Samples were fractionated based on molecular weight and polarity. The data presented here provide evidence for the uniformity in composition of Caramel Colour IV with respect to molecular weight distribution, to nitrogen and sulphur content and their distribution throughout the fractions, to absorbance properties and to specific low molecular weight compounds. Thus, it can be concluded that Caramel Colour IV exhibits compositional uniformity within the range of colour intensity required by the food industry worldwide.

Candy↗
PubMed1992

Characterization of Caramel Colours I, II and III.

Groups of representative samples of Caramel Colours I, II, and III were characterized in order to assess the compositional uniformity within each class and to determine differences between each class. Compositional uniformity within each class was demonstrated by fractionation of the caramel samples and analysis by UV and visible absorbance, HPLC and chemical analysis. Although there was overlap between certain parameters of one or more caramel colour classes, the overall 'fingerprint' for each class, based on several different parameters, was distinctly unique. Such parameters included net ionic charge, absorbance properties, nitrogen and sulphur content, specific low molecular weight compounds and HPLC profiles. HPLC analysis revealed unique profiles within each class and distinct differences between classes. The data presented here for Caramel Colours I, II, and III, and elsewhere for Caramel Colour IV, indicate that each of the four classes can be considered as separate and that, throughout each class, the samples characterized constitute a homologous series of mixtures in terms of chemical composition.

Candy↗
PubMed1992

Development of specifications for caramel colours.

Specifications have been developed to define each of the four classes of caramel colour. The specifications were based on analysis of a large database generated during the course of characterization studies of each of the classes. A series of simple and practical tests was developed for the analysis of caramel colour samples to ensure conformity to the specifications.

Candy↗
PubMed1992

[Serotyping of 48 isolates of Candida albicans: predominance of serotype A over B in Venezuela].

The study of serotyping of isolates of Candida albicans of clinical material obtained from different geographic areas of Venezuela suggest that serotype A is predominant over type B. These results are in relation with results obtained in other countries. Type A serotype is predominant in 57 to 100% in the areas studied. Only in 2 cities serotype B was isolated. Both serotypes of Candida albicans were observed in intertriginous, mucosal, inguinal and lung forms. These studies have allowed us to have information about the predominance of serotypes in certain areas of the country.

Agglutination Tests↗
PubMed1991

Early changes in tumor metabolism after treatment: the effects of stereotactic radiotherapy.

Four patients with intracranial neoplasms, two with malignant gliomas and two with brain metastases, were treated with stereotactic radiotherapy. Patients received between 15 and 27.5 Gray of photon irradiation to the central tumor target point; the 80% isodose line covered the periphery of the tumor as determined by contrast enhanced computed tomography. Patients underwent a sequence of three Positron Emission Tomographic scans using [18F]-fluorodeoxyglucose (PET-FDG)--a baseline scan the day before treatment, and follow-up scans 1 and 7 days after treatment. Ratios between the maximal tumor regional cerebral metabolic rate for glucose (rCMRGlu) (T*) and the contralateral remote white matter rCMRGlu (RW), that is, the glucose uptake ratio (T*/RW), were calculated. The percent change in ratios relative to each patient's baseline scan were calculated. Ratios increased 25% to 42% 1 day post-radiotherapy, then decreased to between 10% above and 12% below the baseline value 7 days post-radiotherapy. The T*/RW increased acutely after stereotactic radiotherapy in a fashion similar to that previously described following chemotherapy with a complex multi-drug regimen. A common metabolic pathway may underlie the increase in T*/RW after these different treatments.

Brain Neoplasms↗
PubMed1991

Identification of B- and T-cell epitopes within the MTP40 protein of Mycobacterium tuberculosis and their correlation with the disease course.

Synthetic peptides derived from the amino acid sequence of MTP40, a recently characterized Mycobacterium tuberculosis protein, were tested by two different immunological assays in 91 individuals. For the purposes of this study, the population was distributed in four groups: active tuberculosis (TBC) patients with elevated bacillus loads (BK+), active TBC patients with low bacillus loads (BK-), healthy individuals living in the same household with tuberculous patients (HH), and normal individuals, who had presumably never been in contact with the bacilli (control). We found that T cells of individuals belonging to the HH group showed the highest and most frequent recognition of these peptides in a T-cell proliferation assay, while their antibodies showed the lowest recognition of these peptides when tested by enzyme-linked immunosorbent assay. In contrast, TBC patients revealed an inverse pattern of immune response. Interestingly, one of these peptides (P7) was recognized by T cells of 64% of the HH individuals and by 4.5% of normal donors. Another peptide (P4) was recognized by 55% of sera from BK+ patients and by 5.5% of normal donors. The results presented here indicate the existence of T- and B-cell epitopes within the MTP40 protein. Given the particular recognition pattern of this protein, added to the fact that it appears to be a species-specific antigen of M. tuberculosis, a detailed study of the immune response to it may be useful in the design of more accurate diagnostic tests and an improved vaccine against human TBC.

Amino Acid Sequence↗
PubMed1991

Differences in patient mix: a partial explantation for the excessive Medicare mortality observed in some Puerto Rican hospitals.

Data from a census in a Puerto Rican community were used to retrospectively compare patients admitted to government hospitals in terms of demographic variables, mental status and functional status in the community prior to admission. A total of 268 patients admitted to a hospital at least once during the study period were identified. Patients admitted to government hospitals were poorer, less educated, less functional and had a higher level of mental impairment. However, in comparison to private hospitals, stratified analysis showed consistently higher in-hospital mortality rates among patients admitted to government hospitals when other variables were taken into account.

Age Factors↗
PubMed1990

The effects of extracellular magnesium on myoplasmic [Ca2+] in malignant hyperthermia susceptible swine.

It is now well established that the pathophysiology of the malignant hyperthermia (MH) syndrome is related to a malfunction of intracellular calcium homeostasis. Magnesium plays important roles in the basic contractile properties of muscle, and many of its actions are antagonistic to those of calcium. The aim of this study was to determine the effectiveness of magnesium sulphate to prevent the MH episode in susceptible animals and correlate this with its effects on the intracellular free calcium [( Ca2+]i). The experiments were carried out using six control (Yorkshire) and ten MH-susceptible crossbred swine (Poland China X Pietrain). After determination of resting concentrations of [Ca2+]i and [Mg2+]i, each animal was given either two iv bolus doses of 50 mg/kg or one iv bolus of 100 mg/kg of MgSO4. The resting [Ca2+]i and [Mg2+]i were determined by means of ion-selective microelectrodes. The resting [Ca2+]i in normal muscle fibers was 0.11 +/- 0.01 microM (mean +/- SEM), whereas in the MH muscles the resting [Ca2+]i was 0.36 +/- 0.01 microM. In neither group was the resting [Ca2+]i modified by MgSO4. This cumulative dose of MgSO4 (100 mg/kg) was not able to prevent the induction of an MH episode by 2% halothane. Although MgSO4 did not directly decrease [Ca2+]i, it did attenuate the increase in [Ca2+]i associated with the syndrome from 7.29 +/- 0.43 microM in untreated animals to 0.84 +/- 0.03 microM in MgSO4 pretreated swine. In addition, the limb rigidity that accompanies this increase in calcium was prevented by MgSO4 pretreatment. Baseline measurements of [Mg2+]i were not different in control and MH-susceptible muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

A Bayesian analysis of the slope ratio bioassay.

The analysis of biological assays has received the attention of statisticians for many years. However, when an indirect assay is considered and a continuous response variable is measured, the standard models lead to the problem of estimating a ratio, which has proved to be rather controversial if the statistical analysis is conducted under the classical approach. In this paper, within the Bayesian framework, the reference posterior distribution of slope ratio is obtained. This is the parameter of interest in a large class of biological assays. The results obtained are provided to avoid the drawbacks of the classical methods and generalize previous Bayesian analysis of the ratio of normal means.

Animals↗
PubMed1989

Platelet monoamine oxidase in Parkinson patients: effect of L-deprenyl therapy.

Platelet MAO activity was measured in 79 Parkinson patients (56 males and 23 females) before and during L-deprenyl therapy. Baseline platelet MAO activity was higher in females than in males with no age dependent differences. During chronic L-deprenyl therapy, MAO activity was inhibited greater than 98%. Four hours after the oral administration of the first 5 mg dose of L-deprenyl, platelet MAO activity was inhibited by 86%. By 24 hours, greater than 98% inhibition was achieved and this degree of inhibition was maintained during continuous L-deprenyl administration. Following oral administration of 10 mg L-deprenyl once a day versus 5 mg L-deprenyl twice a day, the time course of platelet MAO inhibition was similar. Five days after the termination of chronic L-deprenyl therapy, platelet MAO activity was still inhibited by 96%. MAO activity returned to normal by 2 weeks after stopping L-deprenyl. Platelet MAO activity is a useful method of monitoring bioavailability, compliance, dose-response relationship and optimal dosage schedules for L-deprenyl in Parkinson patients.

Adult↗