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Biomedical subjects

J Fernández

Publications and source records attributed to J Fernández.

At least 19 recordsLinked to original sources
PubMed1995

Nitrogen-source-induced activation of neutral trehalase in Schizosaccharomyces pombe and Pachysolen tannophilus: role of cAMP as second messenger.

Resting cells of the fission yeast Schizosaccharomyces pombe, suspended in buffer with glucose, responded to the addition of asparagine by increasing trehalase activity. This response was preceded by a peak in cAMP concentration. The addition of the nitrogen source to resting cells, devoid of the catalytic subunit of cAMP-dependent protein kinase, produced the transient increase in cAMP but did not promote any change in trehalase activity. In the budding yeast Pachysolen tannophilus, the activation of trehalase by nitrogen source was also accompanied by a sharp peak in cAMP. These results suggest that in the two yeasts cAMP acts as a second messenger in the transduction of the nitrogen-source-induced signal causing the activation of trehalase.

Asparagine↗
PubMed1995

Activation of neutral trehalase by glucose and nitrogen source in Schizosaccharomyces pombe strains deficient in cAMP-dependent protein kinase activity.

Schizosaccharomyces pombe cells carrying a disruption in the PKA1 gene, that encodes the catalytic subunit of cAMP-dependent protein kinase (PKA), lacked the glucose- and nitrogen-source-induced activation of trehalase at stationary-phase but rised trehalase activity in response to these compounds during the exponential phase of growth. Treatment by phosphatase of either glucose- or nitrogen-source-activated trehalase resulted in trehalase deactivation suggesting that phosphorylation of the enzyme protein occurs during activation. These data indicate that in growing cells of this yeast the mechanism responsible for the activation of trehalase can be independent of interactions with free catalytic subunits of PKA and related to a signaling pathway involving a type of protein kinase different from PKA.

Cyclic AMP-Dependent Protein Kinases↗
PubMed1995

Experimental model for local administration of nerve growth factor in microsurgical nerve reconnections.

An experimental model for local administration of neuronotrophic substances at the site of peripheral nerve lesion is presented. The model consists of a subcutaneously located silicone reservoir and a connecting tube with its distal end fixed in the proximity of the severed and repaired nerve. The results of the preliminary tests of the model are presented. Sixty Sprague-Dawley rats were divided into two groups: control (saline-treated) (n = 30) and NGF-treated (n = 30). After axotomy of the sciatic nerve, an epineurial repair is performed. NGF or saline is injected daily into the subcutaneous reservoir during the first 3 weeks after axotomy and a single dose in the fourth week. The regenerated nerve observed in the NGF-treated group after four weeks of treatment presents a greater percentage of myelinated axons, thicker myeline sheaths, and more mature endoneurial layers. This experimental model provides a reliable and quantitative way to deliver neuronotrophic substances in site and at different administration rates.

Animals↗
PubMed1995

Granulomatous interstitial nephritis associated with hydrochlorothiazide/amiloride.

A 74-year-old woman developed acute renal failure and granulomatous interstitial nephritis associated with hydrochlorothiazide/amiloride. On stopping the drug the renal function improved, but not significantly. Around 20 months after prednisone administration, the renal function had stabilized, with a moderate degree of renal insufficiency. The case is discussed, and some aspects of acute interstitial nephritis induced by diuretics are briefly reviewed.

Acute Kidney Injury↗
PubMed1995

Insulin-like growth factor binding proteins in arterial hypertension: relationship to left ventricular hypertrophy.

OBJECTIVE: It was reported previously that circulating insulin-like growth factor I levels are abnormally elevated in patients with essential hypertension and left ventricular hypertrophy. Tissue availability of the factor depends on the distribution of the circulating bound factor between its high- and low-molecular mass binding proteins, only the latter being able to cross the endothelium. The aim of this study was to investigate whether the presence of the different serum binding proteins is altered in patients with essential hypertension and left ventricular hypertrophy. DESIGN: The study was performed in 30 never-treated patients with essential hypertension and 30 age- and sex-matched normotensive subjects. Patients were separated into two groups according to the presence or the absence of echocardiographically determined left ventricular hypertrophy. METHODS: Plasma insulin-like growth factor I levels were determined by specific radioimmunoassay. The different molecular forms of its serum binding proteins were analysed by Western blotting using [125I]-labelled insulin-like growth factor I. A densitometric scanning of the blots was performed to analyse the quantitative relationships between the different forms of binding proteins. RESULTS: Insulin-like growth factor I levels were significantly higher in the hypertensive patients with than in the hypertensive patients without left ventricular hypertrophy or in the normotensive subjects. Compared with the normotensive subjects, both hypertensive patients subgroups exhibited increased high-molecular mass binding protein type 3 and decreased low-molecular mass binding proteins types 1 and 2. However, changes in the binding proteins were more marked in the hypertensive patients without than in the hypertensive patients with left ventricular hypertrophy. Accordingly, the ratio of low- to high-molecular mass binding proteins (an index of insulin-like growth factor I bioavailability) was higher in the hypertensive patients with than in the hypertensive patients without left ventricular hypertrophy. CONCLUSIONS: These results show that the distribution of the molecular forms of serum insulin-like growth factor binding proteins is altered in patients with essential hypertension, independently of insulin-like growth factor I levels. This suggests that regulation of the binding proteins is abnormal in essential hypertension. Whether the tissue availability of circulating insulin-like growth factor I is higher in hypertensive patients with than in hypertensive patients without left ventricular hypertrophy merits further investigation.

Adult↗
PubMed1994

Formation of the male pronucleus, organization of the first interphase monaster, and establishment of a perinuclear plasm domain in the egg of the glossiphoniid leech Theromyzon rude.

Whole-mounted or sectioned eggs of the glossiphoniid leech Theromyzon rude were studied under the dissecting, fluorescence, light, and electron microscope. The egg is often penetrated by a single sperm that enters the animal hemisphere and becomes subjected to migration block. The latter is released shortly before or after discharge of the first pole cell, when the sperm centrosome initiates aster formation, the nucleus begins to be untwisted, and its chromatin decondensed. Sperm centration occurs along one side of the egg and appears to follow an arc-like trajectory as a result of vegetal and inward movements affected by colchicine and cytochalasin B but not by taxol. Results indicate that growing microtubules are needed for both movements, whereas actin filaments are essential for the vegetalward movement only. The sperm centrosome becomes the main microtubule organizing center (MTOC) of the egg and concomitantly originates the elaborate first interphase monaster. Additional peripherally situated MTOC form cytaster-like bodies whose visualization is improved by taxol treatment. A voluminous centrosphere, formed around the sperm centrosome, becomes a center of organelle accumulation, giving rise to a perinuclear plasm domain. This process seems to involve both import and replication of organelles.

Animals↗
PubMed1994

[Clinical and serologic course of patients with mixed connective tissue disease].

The so called mixed connective tissue disease (MCTD), continues to be a controversial entity, while some authors considered it a good characterized disease, others think that is an undifferentiated connective tissue disease. OBJECTIVE. To analyse the clinical and serological evolution of a group of patients diagnosed of MCTD, with particular consideration to the meaning of anti-nRNP and anti-Sm antibodies. METHOD. We have studied 20 patients diagnosed of MCTD and 112 with systemic lupus erythematosus (SLE). Anti-nRNP and anti-Sm antibodies were detected through counter immunoelectrophoresis, immunoblotting and ELISA. RESULTS. After an average time of evolution of 10 years, 70% (14/20) of the patients diagnosed of MCTD fulfill criteria for SLE (6 cases), scleroderma (6 cases) or polymyositis (2 cases). Anti-nRNP response is persistent, directed mainly against the 70 Kd and A-nRNP polypeptides and qualitatively higher in MCTD in SLE (absorbencies 2.64 vs 1.25. The immunoblotting test detected anti-Sm antibodies in 5 patients (25%) and ELISA test in 14 (70%). CONCLUSIONS. Clinical and serological evolution suggest that MCTD is an undifferentiated connective tissue disease. Anti-nRNP antibodies are characteristic, although anti-Sm antibodies can be detected with ELISA regardless whether on not patients fulfill SLE criteria.

Adolescent↗
PubMed1992

Coexistence of essential thrombocythemia and multiple myeloma.

We describe a patient with essential thrombocythemia (ET) who developed multiple myeloma (MM) 5 years after the initial diagnosis. A review of the literature revealed no additional reports of the association of these two diseases. Development of MM was not related to treatment of essential thrombocythemia. This association suggests an alteration at the pluripotential stem cell level.

Aged↗
PubMed1992

Rotavirus detection by dot blot hybridization assay using a non-radioactive synthetic oligodeoxynucleotide probe.

A synthetic oligodeoxynucleotide of 40 nucleotides corresponding to nucleotides 33-72 of the gene coding for the viral protein VP7 of rotavirus, was used as a nucleic acid probe to develop a non-radioactive hybridization method for rotavirus detection. The probe was labelled at the 3' end with biotin-7-dATP. The sensitivity and specificity of the dot blot hybridization assay for rotavirus detection was evaluated with 303 stool specimens. The results indicate that the hybridization assay has a higher sensitivity than both PAGE and EIA. Among the rotavirus strains tested 37 different electropherotypes were found. The results suggest that rotavirus diagnosis by dot hybridization using a non-radioactive probe may become routine laboratory procedure because it is simple, highly specific and very sensitive.

Base Sequence↗
PubMed1992

Effects of enalapril on heart failure in hypertensive patients with diastolic dysfunction.

Ten hypertensive patients with symptoms of heart failure and normal systolic function but with diastolic dysfunction were treated with 10 mg enalapril twice a day for 9 +/- 3 months to evaluate the effects of this agent alone on heart failure induced by diastolic dysfunction. After therapy, all patients improved and echocardiographic parameters of diastolic dysfunction became normalized. It is concluded that enalapril appears to be useful in the treatment of heart failure in hypertensive patients with normal systolic function and diastolic dysfunction.

Adult↗
PubMed1992

Nosocomial transmission of rotavirus from patients admitted with diarrhea.

We studied the transmission of rotavirus (RV) in 950 patients under 2 years of age hospitalized for diarrhea in Santiago, Chile. Stool samples were collected every other day from all patients during their entire hospital stay. To trace nosocomial transmission, we mapped the ward at the time of detection of RV. Comparative study by polyacrylamide gel electrophoresis of 315 RV isolates (180 detected upon admission of patients and 135 attributed to nosocomial transmission) allowed the identification of 18 different electropherotypes. An electropherotype similar to that of a community-acquired case was found in the same room in 81% of nosocomial cases and in the ward in 92% of nosocomial cases. It was concluded that the infants admitted shedding RV are the major source of nosocomial transmission and there was not a RV strain that was particularly transmissible.

Chile↗
PubMed1992

[Cause of death, survival, and prognostic factors in a series of 98 patients with chronic myeloid leukemia].

PURPOSE: To analyse the survival from diagnosis to blastic crisis, as well as the causes of death and the significance of different features in patients diagnosed of chronic myelogenous leukaemia (CML). MATERIAL AND METHODS: The series includes 98 patients who died of CML in Asturias Central Hospital and other nearby hospital between 1970 and 1990. The CML diagnosis had been established according to conventional criteria. The blastic crisis was diagnosed in accordance with morphologic and cytochemical studies, complemented in some cases with the assay of TdT or other markers. The Kaplan-Meier curves and long-rank test were applied to the statistical analysis of survival. The prognostic factors were evaluated by univariate correlation. RESULTS: The series' mean age was 48.57 years (range: 6-90) and the M/F ratio was 56/42. Cytogenetic study had been performed in 35 patients, of whom 33 had the Ph' chromosome. Death occurred in the blastic crisis in 67 cases (72%), in the accelerated phase in 14 cases (15%) and in the chronic phase in 12 cases (13%). The cause of death could be determined in 47 cases; of them, 24 (51%) died of infection, 11 (23.4%) of haemorrhage, and the remaining 12 (25.6%) of different complications. The median survival of the group as a whole was 32 months (range: 4-137). For the blastic crisis this figure was reduced to 2.5 months (range: 1-14), the lymphoid forms doing better, 5 months, than the non-lymphoid ones; 1.5 months (p < 0.03). Out of the data evaluated at diagnosis, only haemoglobin and the percentage of blast cells in peripheral blood showed any correlation with survival (r = +0.28, p < 0.05 for haemoglobin, and r = -0.30, p < 0.01 for blast cells). CONCLUSIONS: (1) Although most patients die from infection or haemorrhage during the blast crisis, CML increases the risk of death in the accelerated and chronic stages as well. (2) Non-lymphoid blastic crisis has poorer prognosis than the lymphoid form. (3) The concentration of blast cells and haemoglobin in peripheral blood at diagnosis acquire prognostic significance in the present study.

Adolescent↗
PubMed1991

Active alpha 2 and beta adrenoceptors in lymphocytes from patients with chronic lymphocytic leukemia.

A single population of alpha 2 adrenoceptors was characterized in intact B lymphocytes from patients with chronic lymphocytic leukemia (B-CLL) by binding and saturation studies with 3H labelled yohimbine and by competition studies with alpha adrenergic antagonists. While the affinity of B-CLL alpha 2 adrenoceptors was low (KD: 9.81 nM-20.98 nM), each cell expressed a large number of receptors. No binding of the alpha 1 adrenoceptor antagonist prazosin was observed and the binding properties of beta adrenergic receptors (assayed with 3H-labelled dihydroalprenolol), were similar to those described for normal lymphocytes. Reaction of B-CLL with the beta adrenergic agonist isoproterenol raised the levels of cAMP in 11/13 patients tested, and in 8 of these, incubation with the alpha 2 adrenergic agonist clonidine prevented the effect and reduced the basal cAMP levels. The presence of active alpha 2 adrenoceptors on B-CLL lymphocytes may be involved in the regulation of metabolic pathways that affect cell functions and favor neoplastic growth.

Aged↗