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Biomedical subjects

M Díaz

Publications and source records attributed to M Díaz.

At least 109 records · Page 6Linked to original sources
PubMed1996

Volume-activated chloride channels in neuroblastoma cells are blocked by the antiestrogen toremifene.

The presence of volume-activated chloride channels has been examined in neuroblastoma C1300 cells using the whole-cell configuration of the patch-clamp technique. Chloride channels could not be detected under isotonic conditions. However, hypotonic challenge induced slowly developed inward and outward anionic currents that exhibited outward rectification and inactivation at the most depolarizing potentials, features that were similar to the currents described in other cell preparations where volume-activated Cl- channels have been associated with the expression of P-glycoprotein. This hypotonicity-activated Cl- currents could be reversibly blocked by extracellular exposure to toremifene, a novel synthetic antioestrogen. The fact that toremifene and its analog tamoxifen, have been shown to block P-glycoprotein-associated chloride channels and to reverse P-glycoprotein associated multidrug resistance in a number of cell lines suggest that P-glycoprotein could be involved in the generation of hypotonic-induced chloride conductance in neuroblastoma cells.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1996

Prevalence of tuberculin reactivity and prevalence of risk factors for the development of active tuberculosis in a nursing home in Puerto Rico.

A total of 91 nursing home patients were evaluated to determine the prevalence of tuberculous infection and the prevalence of risk factors for active TB in those with positive tuberculin reactions. Overall prevalence rate for positive PPD was 42.9%. No association was found between prevalence of positive PPD and time since admission to the nursing home. The most prevalent risk factors for active TB among PPD positive patients were diabetes mellitus (38.5%), being 10% below ideal body weight (25.6%), chest X ray with fibrotic changes (13.2%), and carcinoma of oropharynx (5.1%). Twenty-one patients (53.8% of patients with positive test) met criteria for prophylactic treatment with isoniazid. This study detected a high prevalence of positive PPD reactions in this nursing home population and a high prevalence of risk factors for the development of active TB in the group with positive reaction to PPD. Due to the high risk for the development of active tuberculosis in this population, aggressive screening and preventive therapy are mandatory.

Aged↗
PubMed1996

Purification and properties of beta-galactosidase from Aspergillus nidulans.

Beta-Galactosidase from mycelial extract of Aspergillus nidulans has been purified by substrate affinity chromatography and used to obtain anti-beta-galactosidase polyclonal antibodies. A. nidulans growing in lactose as carbon source synthesizes one active form of beta-galactosidase which seems to be a multimeric enzyme of 450 kDa composed of monomers with 120 and 97 kDa. Although the enzyme was not released to the culture medium, some enzymatic activity was detected in a cell-wall extract, thus suggesting that it can be an extracellular enzyme. Beta-Galactosidase of A. nidulans is a very unstable enzyme with an optimum pH value of 7.5 and an optimum temperature of 30 degrees C. It was only active against beta-galactoside substrates like lactose and p-nitrophenyl-beta-D-galactoside (PNPG).

Aspergillus nidulans↗
PubMed1996

Prevalence of tuberculin reactivity and risk factors for the development of active tuberculosis upon admission to a nursing home.

A total of 118 nursing home admissions were studied to determine the prevalence of M. tuberculosis infection and the prevalence of risk factors for the development of active tuberculosis. The overall prevalence of positive tests was 22.5%. The most prevalent risk factors for development of active tuberculosis were diabetes mellitus (42.4%), being more than 10% below ideal body weight (41.5%), and alcohol abuse (12.7%). Thirty-four percent of admissions had albumin levels below 3.5 g/dl. No associations were found when logistic regression was used to determine the impact of age and poor nutritional status on the prevalence of positive PPD tests on admission. These results show a substantial difference between the prevalence of positive PPD tests found upon nursing home admissions (22.5%) and the prevalence found previously among residents in the same in nursing home (42.9%).

Age Factors↗
PubMed1996

[Cardiovascular risk factors in 15 patients in chronic hemodialysis in Temuco city. Descriptive comparison with the general Chilean population].

BACKGROUND: Patients in chronic hemodialysis have a high mortality due to cardiovascular diseases. AIM: To study cardiovascular risk factors and nutritional status in a group of patients in maintenance hemodialysis. PATIENTS AND METHODS: Body mass index, blood pressure, serum levels of totals cholesterol, HDL cholesterol, triglycerides and albumin were measured in 15 patients (8 male) in maintenance hemodialysis. Data were compared with available figures for the normal Chilean population. RESULTS: Age ranged from 33 to 60 years old in female patients and from 22 to 63 years old in males. Thirteen subjects (87%) had high blood pressure, all had HDL cholesterol levels below 35 mg/dl, four (27%) had a total cholesterol over 200 mg/dl, three had triglyceride levels over 200 m/dl, two (13%) smoked and none were diabetic. Mean body mass index was normal, albumin levels were 4.16 and 4.02 g/dl and serum creatinine was 11.64 and 9.68 mg/dl in males and females respectively. The estimated prevalence of high blood pressure, hypercholesterolemia and smoking in the general Chilean population range from 9 to 22%, from 50 to 52% and from 45 to 51% respectively. CONCLUSIONS: This group of patients has a high frequency of high blood pressure and low HDL cholesterol levels.

Adult↗
PubMed1996

[Validation of a ultramicroELISA for detecting antibodies against hepatitis B surface antigen].

The results of a validation study of the ultramicroanalitical assay for the detection of antibodies against the hepatitis B surface antigen (UMELISA anti-HBsAg), which was carried out by comparing the results obtained with the Hepanostika anti-HBsAg, commercial diagnosis kit are presented. For this purpose, sera from the clinical assays of the Cuban recombinant vaccine against hepatitis B were used. With the first sera group (n = 30) it was obtained, 93.1% of sensitivity, 98.5% of specificity and a concordance of 94.3%. The correlation coefficient showed a similar trend of the results (p < 0.01) and no significant differences were found in the average geometrical titre (TPG) between both assays (p > 0.05). With the second group (n = 100), whose assays were carried out at the "Pedro Kouri" Institute of Tropical Medicine (PKI) and at the Immunoassay Center (IAC) simultaneously, it was observed a sensitivity of 96.25% in both centers, a specificity of 75% at the PKI and of 90% at the IAC, and a coincidence of 92% and 95%, respectively. The correlation coefficient presented similar values and there were no significant differences between the TPG obtained by the two methods (p > 0.05). The results attained show in general the validity of the new assay and the feasibility to put it into practice either for following up the infection, or for carrying out clinical assays of vaccine evaluations.

Enzyme-Linked Immunosorbent Assay↗
PubMed1995

Characterisation of Ca(2+)-dependent inwardly rectifying K+ currents in HeLa cells.

The whole-cell configuration of the patch-clamp technique was used to examine K+ currents in HeLa cells. Under quasi-physiological ionic gradients, using an intracellular solution containing 10(-7) mol/l free Ca2+, mainly outward currents were observed. Large inwardly rectifying currents were elicited in symmetrical 145 mmol/l KCl. Replacement of all extracellular K+ by isomolar Na+, greatly decreased inward currents and shifted the reversal potential as expected for K+ selectivity. The inwardly rectifying K+ currents exhibited little or no apparent voltage dependence within the range of from -120 mV to 120 mV. A square-root relationship between chord conductance and [K+] at negative potentials could be established. The inwardly rectifying nature of the currents was unaltered after removal of intracellular Mg2+ and chelation with ATP and ethylenediaminetetraacetic acid (EDTA). Permeability ratios for other monovalent cations relative to K+ were: K+ (1.0) > Rb+ (0.86) > Cs+ (0.12) > Li (0.08) > Na+ (0.03). Slope conductance ratios measured at -100 mV were: Rb+ (1.66) > K+ (1.0) > Na+ (0.09) > Li (0.08) > Cs+ (0.06). K+ conductance was highly sensitive to intracellular free Ca2+ concentration. The relationship between conductance at 0 mV and Ca2+ concentration was well described by a Hill expression with a dissociation constant, KD, of 70 nmol/l and a Hill coefficient, n, of 1.81. Extracellular Ba2+ blocked the currents in a concentration- and voltage-dependent manner. The dependence of the KD for the blockade was analysed using a Woodhull-type treatment, locating the ion interaction site at 19% of the distance across the electrical field of the membrane and a KD (0 mV) of 7 mmol/l. Tetraethylammonium and 4-aminopyridine were without effect whilst quinine and quinidine blocked the currents with concentrations for half-maximum effects equal to 7 mumol/l and 3.5 mumol/l, respectively. The unfractionated venom of the scorpion Leiurus quinquestriatus (LQV) blocked the K+ currents of HeLa cells. The toxins apamin and scyllatoxin had no detectable effect whilst charybdotoxin, a component of LQV, blocked in a voltage-dependent manner with half-maximal concentrations of 40 nmol/l at -120 mV and 189 nmol/l at 60 mV; blockade by charybdotoxin accounts for the effect of LQV. Application of ionomycin (5-10 mumol/l), histamine (1 mmol/l) or bradykinin (1-10 mumol/l) to cells dialysed with low-buffered intracellular solutions induced K+ currents showing inward rectification and a lack of voltage dependence.

Adenosine Triphosphate↗
PubMed1995

Adverse drug reactions (ADRs) in patients with previous history of chronic alcohol consumption without signs of chronic hepatic damage. A prospective study.

An intensive and prospective drug surveillance method was used to monitor 105 hospitalized patients having a previous history of chronic alcohol consumption without signs of hepatic damage at the Dr. Sotero del Rio hospital, Santiago, Chile. The aim of the work was to characterize and study the incidence of ADRs associated with chronic alcohol addiction in patients hospitalized for different pathological conditions. The incidence of ADRs in this group (41.9%) was slightly higher than those from other studies carried out in our country in patients hospitalized in the internal medicine service from other Chilean hospitals. However, alcohol addiction was not considered in these studies. According to causality, 58.8% of the ADRs were regarded as probable, 6.9% as definite and 34.3% as possible. The severity of ADRs was determined as 18.6% mild, 53.9% moderate and 27.5% as severe events. These ADRs were manifested in a dose-related fashion (80.4%). Furosemide, heparin, and gentamicin were the drugs mainly associated with ADRs. The most commonly affected system were metabolic (33.3%), renal (19.6%), and gastrointestinal (19.6%). There was a higher incidence of ADRs in those patients with longer stay at the hospital, in patients on multiple-drug therapy, and in patients with impaired renal function. The frequency of ADRs was not related to age, sex, and pattern of alcohol consumption.

Adult↗
PubMed1995

[The efficacy of Salmocumarín rodenticide in livestock-raising and urban sites].

The activity in burrows at four different sites was calculated, and it went from 80 to 98% during pretreatment. For the first time in our country, average values of days/deaths of synanthropic rodents in natural conditions were obtained, and the reached values were between 16.50 and 19.06 after applying the biorodenticide. In the statistical analysis, a significant difference was found in the set of objectives related with days/deaths averages (H = 8.60*; p < 0.05). Moreover, no significant differences were found in percentages of residual activity in burrows (G = 8,27; p < 0.05). Results obtained show that Salmocumarín biorodenticide is much more effective in places where great populations of this species of cosmopolitan rodents exist.

Animal Husbandry↗
PubMed1994

Clinical performance of the Copper T200B IUD after reinsertion following life-span expiration.

The purpose of this study was to evaluate the first year clinical performance of the TCu200B IUD in a cohort of women who had the IUD re-inserted immediately after a removal for life-span expiration, compared with a group of initial acceptors, and a cohort of women who continued using the device for more than 60 months. The sample consisted of 1066 users, 339 in each of the two first groups and 388 in the third. Life-table analysis was used to calculate continuation and gross discontinuation rates by reason. Statistical significance of the differences between groups was tested by log-rank method. Pregnancy rates were low, both in the group of re-insertions and first insertions, and no pregnancies occurred in the group using the device beyond the fifth year. The expulsion rate and lost-to-follow-up (LFU) rate were significantly lower in the group of women who used the device beyond the fifth year. In addition, this group showed a significantly higher rate of removal for investigator's choice. These results show that there is no reason to recommend the removal and replacement of the TCu200B before the end of the sixth year of use. When a new IUD is to be inserted after removal for life-span expiration, providers should be instructed to insert it immediately after the removal, because this procedure does not pose additional risks, reduces the number of clinic visits, and relieves the women of the use of a temporary method while waiting for the re-insertion.

Adult↗
PubMed1994

[Early pregnancy risk: development and validation of a predictive instrument].

An early pregnancy risk scale, with scores ranging from 11 to 66 points from lower to higher risk, was constructed using variables associated with teenager's pregnancy. This scale was applied to 3000 female teenagers, coming from Metropolitan Santiago public schools. The sample was divided in three risk groups: group A (high risk) with scores equal or over 35 points, group B (low risk) with scores equal or below 20 points and group B (intermediate risk) with scores between 20.1 and 34.9 points. These girls were followed during 2 years. During this period, 84 girls became pregnant, 24 of 184 (13%) in group A, 60 of 2332 (2.6%) in group C and none of 307 in group B. There were 104 school desertions in group A and 37 in group B. To study associations and analyze risk, the sample was divided in two risk groups: high, with scores over 27 and low, with scores below 27. There was a high association between pregnancy risk score and the occurrence of pregnancy (RR 5.25 p < 0.0001) and school desertion (RR 3.32 p < 0.0001). Pregnancy was predicted with a 78% sensitivity and 55.6% specificity. School desertion was predicted with a 74% sensitivity and 56% specificity. The importance variable weighing using multiple regression models, to improve the predictor's sensitivity and specificity, is discussed.

Adolescent↗
PubMed1994

Petechial glove and sock syndrome caused by parvovirus B19.

The petechial glove and sock syndrome is a recently described febrile dermatosis characterized by acral edema, petechiae in a characteristic distribution, and enanthem, which has been associated in several cases with parvovirus B19 seroconversion. We report an additional case of petechial glove and sock syndrome that further corroborates the role of parvovirus B19 as a causative agent of this syndrome in adults.

Adult↗
PubMed1994

Evaluation of the immune response in symptomatic and asymptomatic human giardiasis.

To better understand the common association of Giardia lamblia infection and allergic reactivity, total and specific IgE values were evaluated and different manifestations of symptomatic and asymptomatic infected human hosts were analyzed. The humoral, cellular, and nonspecific immune responses were evaluated in Cuban adults. Increased total serum IgE levels were significantly higher (p < 0.01) in Giardia patients than in negative controls; cure of giardiasis was characterized by a decrease in IgE levels and some patients regained normal IgE values. The skin test was positive in 91% (103/123) of chronic patients and only in 23% (20/123) of negative controls (p < 0.05). A positive test was seen in patients with antecedents of recent giardiasis (< 4 months). Specific IgE was higher in patients than in control sera, and in the former it decreased with sera dilution. During the follow-up period of cured patients, the proportion of IgE decreased and the opposite occurred in noncured patients. The cellular response evaluated by LIF was positive in 92% (11/12) of carriers and significantly higher (p < 0.05) than in symptomatic patients 8% (1/12); the same occurred with IgG and IgA antibody response; titers mainly of IgA were higher in asymptomatic carriers than in patients; all carriers were negative to the skin test. These results indicate the presence of total and specific IgE responses in humans infected with Giardia, but the response in symptomatic cases (patients) is different from that in asymptomatic cases (carriers).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

[Detection of anti-gonococcal antibodies using a dot immunobinding assay in a high risk female population].

The bacteriological diagnosis of gonorrhea in women has a low efficiency. A dot immunobinding assay, using whole piliated Neisseria gonorrhoeae cells, was used to detect antigonococcal antibodies in 300 prostitutes in whom a parallel Thayer-Martin culture of endocervical secretion was performed. Twenty sera from men with bacteriologically confirmed gonorrhoea were used as positive controls and 20 sera from children without history of gonococcal infections, as negative controls. Antibodies were detected in 49.7% of women and culture was positive in only one. All men with gonorrhea has positive titers and all sera from children were negative, except one that had a cross-reaction. Test sensitivity in the female population was 1 and specificity 0.5. There were no false negative reactions. Although the test detected antibodies in high risk women, there were cross-reactions. Therefore, the technique should be improved, using a more specific antigen.

Antibodies, Bacterial↗
PubMed1993

The Schizosaccharomyces pombe cwg2+ gene codes for the beta subunit of a geranylgeranyltransferase type I required for beta-glucan synthesis.

The product of the Schizosaccharomyces pombe cwg2+ gene is involved in the biosynthesis of beta-D-glucan. When grown at the non-permissive temperature, cwg2-1 mutant cells lyse in the absence of an osmotic stabilizer and display a reduced (1-3) beta-D-glucan content and (1-3) beta-D-glucan synthase activity. The cwg2+ gene was cloned by the rescue of the cwg2-1 mutant phenotype using an S. pombe genomic library and subsequently verified by integration of the appropriate insert into the S. pombe genome. Determination of the nucleotide sequence of this gene revealed a putative open reading frame of 1065 bp encoding a polypeptide of 355 amino acids with a calculated M(r) of 40,019. The cwg2+ DNA hybridizes to a main transcript, the 5' end of which maps to a position 469 bp upstream of the predicted start of translation. The sequence between the transcription and the translation start sites is unusually long and has several short open reading frames which suggest a translational control of the gene expression. Comparative analysis of the predicted amino acid sequence shows that it possesses significant similarity to three Saccharomyces cerevisiae proteins, encoded by the DPR1/RAM1, CDC43/CAL1 and ORF2/BET2 genes respectively, which are beta subunits of different prenyltransferases. When grown at 37 degrees C, cwg2-1 mutant extracts were specifically deficient in geranylgeranyltransferase type I activity, as measured in vitro. Multiple copies of the CDC43 gene can partially suppress the growth and (1-3) beta-D-glucan synthase defect of the cwg2-1 mutant at the restrictive temperature. In a similar manner, the cwg2+ gene can partially suppress the cdc43-2 growth defect. These results indicate that cwg2+ is the structural gene for the beta subunit of geranylgeranyltransferase type I in S. pombe and that this enzyme is required for (1-3) beta-D-glucan synthase activity. The functional homology of Cwg2 with Cdc43, which has been implicated in the control of cell polarity, suggests a link between two morphogenetic events such as establishment of cell polarity and cell wall biosynthesis.

Amino Acid Sequence↗
PubMed1993

Volume-activated chloride channels in HeLa cells are blocked by verapamil and dideoxyforskolin.

The possible role of Cl- currents in regulatory volume decrease processes has been explored in HeLa cells using the whole-cell recording mode of the patch-clamp technique. Cells showed very small currents in voltage-clamp experiments performed with Cl(-)-rich, permeant-cation-free (N-methyl-D-glucamine replacement) intracellular and bathing solutions. Exposure of the cells to hypotonic solutions visibly swelled the cells and activated, reversibly, an outward rectifying Cl- current, which decayed at the most depolarised voltages used. Replacement of extracellular Cl- by a series of halide anions, SCN- and gluconate was consistent with an anion selectivity sequence: SCN- > I- > Br- > Cl- > F- > gluconate. The volume-regulated Cl- current was effectively inhibited by 100 microM 5-nitro-2-(3-phenyl-propylamino)-benzoic acid and by 100 microM 4,4'-diisothiocyanotostilbene-2,2-disulphonic acid, substances known to block Cl- channels in a variety of cells. Chloride current activation by hypotonicity was dependent on the presence of ATP in the intracellular solution and this requirement could be replaced by the non-hydrolysable analogue ATP[gamma S] and Mg(2+)-free ATP. The data suggest that the channels responsible for the current described are involved in the regulatory volume decrease in HeLa cells. The characteristics of this Cl- current are similar to those of the current associated with expression of multidrug resistance P-glycoprotein. Furthermore, the currents in HeLa cells were inhibited rapidly and reversibly by verapamil and 1,9-dideoxyforskolin, which are known to inhibit P-glycoprotein function.

Adenosine Triphosphate↗
PubMed1993

Quality of care in family planning in Latin America.

The majority of family planning programs in Latin America have been implemented in response to the region's population growth and aimed mainly at obtaining quantitative results, leaving quality, from the user's point of view, in second place. Recent decades have witnessed an increasing concern for quality of care in family planning because most researchers and service providers began to realize that when contraceptive methods are delivered without maintaining high quality levels, continuation rates are usually low and the image of methods and services is impaired. This paper reviews the level of quality of services in family planning in Latin America following Judith Bruce's framework and proposes, some activities that may improve it. The analysis found severe deficiencies in almost all the elements mentioned by Bruce, mainly in choice, technical competence, and mechanisms for improving continuity. The authors propose that to improve quality, services should (a) generate top management commitment to quality, (b) stay close to the client/user, (c) improve work conditions of providers/health workers, (d) measure quality, and (e) reward quality. The authors' conclusions are that (a) better quality services lead to better program results, (b) high quality is cost-effective, (c) managerial commitment is critical to improvement of quality, and (d) quality of care is not a luxury; it is necessary and possible in all settings.

Clinical Competence↗