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Biomedical subjects

R Torres

Publications and source records attributed to R Torres.

At least 109 records · Page 6Linked to original sources
PubMed1992

Myocardial inositol and sodium in diabetes.

Although inhibition of Na(+)-K+ ATPase has been described in the diabetic heart, K+ loss from myocardium has not been observed in a canine model of mild diabetes. The finding of tissue Na+ accumulation and a potential relation to alteration of left ventricular inositol as observed in other tissues in diabetes form the basis of this investigation. Diabetes was induced with alloxan in three groups of male mongrel dogs who were studied after 1 yr. In the initial experiment the tissue compartment volumes, determined with intravenous 51Cr EDTA as a marker, were found to be normal. Calculated cell sodium was increased to 32.8 +/- 2.6 mEq/kg cell H2O vs 18.7 +/- 1.1 in controls (p < 0.01). Cell potassium in diabetes was normal. In the second group, myocardial polyols were analyzed by gas-liquid chromatography. Inositol was diminished in diabetes to 0.61 +/- 23 microM/g of left ventricle, vs the respective control levels of 1.9 +/- 0.57 microM/g (p < 0.02). Sorbitol concentration was unaltered. Left ventricular sodium increments were not associated with altered tissue calcium. In group III the hypothesis that inhibition of Na(+)-K+ ATPase in diabetes might not elicit the expected alteration of K+ transport was assessed during intracoronary infusion of acetyl strophanthidin. No difference in cation responses from control was observed. It is postulated that a change in the conformation of Na(+)-K+ ATPase, with high affinity sodium binding sites facing the intracellular compartment, may render sodium less releasable from cell membrane.

Animals↗
PubMed1992

Myc and Max: a putative transcriptional complex in search of a cellular target.

Biochemical and genetic observations have supported the hypothesis that Myc family proteins function to regulate genes important in cellular growth and differentiation. The recent findings that Myc proteins can associate with other cellular proteins, possess sequence-specific DNA-binding activity and may directly transactivate transcription of several candidate genes have provided an experimental framework in which to test the transcription factor model. Based on principles established for several well characterized viral oncoproteins, a model is presented in which the regulation of Myc function is controlled by specific cellular protein interactions that serve to activate or repress transactivation activity or deny access of the Myc complex to its target sequences.

Animals↗
PubMed1992

Characterization of large-conductance chloride channels in rabbit colonic smooth muscle.

1. A large-conductance Cl- channel was characterized in cell-free membrane patches from the rabbit longitudinal colonic smooth muscle using the patch clamp technique. In addition, the regulation of these channels by neurokinin-1 (NK-1) receptor agonists and G proteins was studied. 2. No spontaneous channel activity was observed in cell-attached patches at the cell resting potential, or in excised patches at pipette potentials (Vp) between -20 and 20 mV. In excised patches, channel activity could be induced in thirty-six out of ninety-six patches by holding the patch at Vp values more negative than -60 mV or more positive than 60 mV. Once induced, the channel showed a bell-shaped voltage activation curve in high symmetric [Cl-], with maximal open probability between 20 and -5 mV. Varying cytosolic calcium concentration ([Ca2+]) between 5 x 10(-8) M and 1.0 mM had no effect on the voltage activation of the channel. 3. In inside-out and outside-out patches, when pipette and bath solutions contained equal [Cl-] (130 mM), the anion channel showed a linear current-voltage (I-V) relationship between -60 and 60 mV with a slope conductance of 309 +/- 20 pS (n = 13). Reversal potential measurements indicated that the channel was selective for Cl- over Na+ and K+ (PCl/PNa = 6:1). 4. Channel openings from the closed state to the full open state as well as transitions through smaller conductance states were observed. The smallest detectable substate had a conductance of 15.6 pS. Based on the similarities in selectivity and linearity of the I-V curve of the smaller conductances with the full open state, and kinetic analysis of channel activity, it is concluded that the large conductance channel is composed of multiple substates which can either open and close independently, or simultaneously via a main gate. 5. The stilbene derivative diiso-thiocyanato-stilbene-disulphonic acid (DIDS) and the diphenylamine-2-carboxylate analogue 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) caused a dose-dependent, reversible flicker block of the small conductance and significantly reduced the macroscopic current flow through the channel. 6. In quiescent outside-out patches, when the pipette contained a 140 mM-CsCl solution with 10(-6) M-CaCl2, 1.2 mM-MgCl2 and 1 mM-GTP, and the bath contained Ringer solution, addition of the NK-1 receptor antagonists substance P methylester resulted in activation of the full conductance state and of smaller substates.(ABSTRACT TRUNCATED AT 400 WORDS)

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1992

[Fasciola hepatica infestation. Biopathology and new diagnostic and therapeutic aspects].

We present here 6 patients with Fasciola hepatica infection, all from rural origin, and with the risk factors of eating wild watercress. The more common symptoms were: fever (83%), abdominal pain (100%), weight loss (83%) and generalized myalgia and joint pain (67%). All patients presented with an absolute eosinophil count above 1,000 cell/mm3. The diagnosis was established in five cases by means of serologic techniques (haemagglutination) and with direct visualization of adult worms while surgery in one case. A CT abdominal scan was performed in five patients, revealing specific lesions of tissue infiltration in four of them. Praziquantel was used in four patients, achieving clinical cure in three cases. In two patients, bithionol was used, with clinical cure in both cases. We review also some newer diagnostic and therapeutic approaches to this parasitic disease.

Adult↗
PubMed1991

The glucocorticoid hormone signal transduction pathway in mice homozygous for chromosomal deletions causing failure of cell type-specific inducible gene expression.

Wild-type newborn mice are characterized by the ability of certain liver-specific genes encoding various enzymes and mapping on different chromosomes to respond to glucocorticoid induction. Newborn mice homozygous for deletions at and around the albino locus on chromosome 7 fail to develop this competence for hormone-inducible gene expression even through they do show normal constitutive expression of the same genes. Studies of the glucocorticoid hormone signal transduction pathway reported here show identical expression of glucocorticoid receptor mRNA and protein in deletion homozygotes and normal littermates. Furthermore, the receptor interacts normally with the 90-kDa heat shock protein hsp90. Elevated glucocorticoid hormone levels in newborn deletion homozygotes, most likely resulting from their stressed condition, provide an explanation for the reduced binding activities of receptors reported previously. The elimination of receptors and hormones as direct targets of the chromosomal deletion effects suggests that the failure of inducible gene expression might reside in defective competence of the affected structural genes to respond to the hormonal stimulus.

Animals↗
PubMed1991

[Septic thrombophlebitis of the great vessels of the neck. A severe complication of central venous catheters].

Septic thrombophlebitis of the large veins of the neck is an uncommon, but extremely severe, complication in carriers of central venous catheters. Treatment of these cases is difficult and, generally, the clinical condition does not permit surgical approach. Four patients with septic central vein thrombophlebitis are reported. They were treated with conservative measures including catheter removal and high-dose parenteral antibiotics for at least four weeks, with excellent results in all. The relevant literature and the therapeutic alternatives are reviewed.

Adult↗
PubMed1991

Cellular immunodeficiency in Paget's disease of bone: changes induced by treatment with elcatonin.

We have found a cellular immune defect (low CD4 T lymphocyte count, high CD8 T lymphocyte count and a low CD4/CD8 ratio) in 39 PDB patients. This finding is not correlated with the bone metabolic activity of the disease. There was an improvement in the cellular immune defect in fifteen patients after treatment with elcatonin. These changes could be related to the improvement in the metabolic derangement or else could be the consequence of an effect on altered immunity.

Aged↗
PubMed1991

Clinical usefulness of serum tartrate-resistant acid phosphatase in Paget's disease of bone: correlation with other biochemical markers of bone remodelling.

Tartrate resistant acid phosphatase (TRAP) has been proposed as a new biochemical marker for bone resorption. We have compared this new marker, TRAP, with the classical biochemical markers of bone remodelling, serum alkaline phosphatase (sAP), serum osteocalcin (sBGP), and with the urinary hydroxyproline/creatinine ratio (uOHProl/creatinine), a routine marker of bone resorption. Serum TRAP was significantly higher in pagetic patients (n = 43) than in control subjects (n = 12) (13.02 +/- 4.7 vs 5.48 +/- 1.31 IU/L, P less than 0.001) and a significantly positive linear correlation was found between the sTRAP and uOHProl/creatinine ratio (y = 0.0051x - 0.0069, r = 0.82, P less than 0.001), between sTRAP and sAP (y = 19.3x - 85.0, r = 0.71, P less than 0.001) and also between sTRAP and sBGP (y = 0.02x + 2.23, r = 0.52, P less than 0.01). Serum TRAP levels were higher than the upper limit of normality in all our pagetic patients except for two, whose uOHProl/creatinine levels were in the normal range. We conclude that (1) sTRAP could be a parameter as sensitive as uOHProl/creatinine in the diagnosis of Paget's disease; (2) sTRAP and uOHProl/creatinine are both good markers of bone resorption; (3) the correlation found between sTRAP and formation markers (sAP and sBGP) makes sTRAP a marker of disease activity in Paget's disease of bone; (4) the assay of sTRAP is easier, faster, and of lower cost than the urinary hydroxyproline determination. We suggest that sTRAP determination could be used as a routine marker of bone resorption in Paget's disease of bone, as is the case with uOHProl determination.

Acid Phosphatase↗
PubMed1991

Binding of serum osteocalcin to hydroxyapatite in Paget's disease of bone.

Serum osteocalcin (serum bone Gla protein, sBGP) is elevated in diseases characterized by an enhanced bone turnover. However, in Paget's disease of bone there is a discrepancy between the low increase of sBGP and the high increase of bone remodelling assessed by serum alkaline phosphatase and urinary hydroxyproline. It is possible that the relatively low levels of sBGP reflect an abnormal binding of the molecule to the bone due to an alteration of the BGP molecule and/or of the pagetic mineral phase of bone. Another possibility would be a disregulation of BGP synthesis. In the present work we studied the binding of pagetic sBGP to an experimental model of mineral phase of bone (HPLC hydroxyapatite column). Serum of 14 patients with Paget's disease of bone (sBGP = 7.8 +/- 3.5 ng/ml) and of 14 control subjects (sBGP = 3.3 +/- 0.9 ng/ml) was purified through a Sephadex G-50 medium column (2.6 x 100 cm, 5 mM NH4CO3H). The BGP peak was lyophilized and resuspended in 1 mM KH2PO4, 1 mM CaCl2, 0.02% NaN3, pH 8.4, and then injected into an HPLC gradient system (Waters 660), from 1 to 300 mM KH2PO4 through a hydroxyapatite column (BioGel HPHT, Bio-Rad, 0.78 x 10 cm). A single peak of sBGP was obtained with a retention time of 12 min in control and pagetic patients. From these results we conclude that BGP binding to hydroxyapatite is similar in pagetic patients and in control subjects, suggesting that an alteration in BGP molecule is not responsible for an abnormal binding to the bone. In order to validate our system, the binding of serum BGP from warfarin-treated rats to the hydroxyapatite HPLC column was also studied and compared to binding of serum BGP from normal rats.

Aged↗
PubMed1991

Correlation between serum osteocalcin and 24,25-dihydroxyvitamin D levels in Paget's disease of bone.

We have studied the possible correlation between serum 24,25-dihydroxyvitamin D [24,25-(OH)2D] and osteocalcin levels (sBGP) in Paget's disease of bone. We measured serum calcium, phosphate, PTH, 25-hydroxyvitamin D, 1,25-(OH)2D, 24,25-(OH)2D, alkaline phosphatase (sAP), and the urinary hydroxyproline/creatinine ratio (UOH prol/creat) in 19 patients with Paget's disease of bone and 16 age- and sex-matched controls. As expected, sAP, UOH prol/creat, and sBGP levels were significantly elevated, and there was a tendency to a decrease in serum levels of 24,25-(OH)2D in Pagetic patients with respect to the control group. There was no significant difference between patients and controls in serum calcium, phosphate, PTH, 25-hydroxyvitamin D, and 1,25-(OH)2D. The Pagetic patients were subdivided into two subgroups; subgroup A had normal sBGP levels (less than 5 ng/mL), and subgroup B had increased sBGP levels (greater than 5 ng/mL). Serum 24,25-(OH)2D levels in subgroup B were significantly lower than those in controls, while subgroup A showed levels similar to those in the control group. We also found a positive linear correlation between sAP and sBGP and between sAP and UOH prol/creat as well as a negative linear correlation between sBGP and 24,25-(OH)2D and between 24,25-(OH)2D and UOH prol/creat in Pagetic patients. These results point to a possible role of 24,25-(OH)2D in disease activity.

24,25-Dihydroxyvitamin D 3↗
PubMed1991

[Endocarditis caused cy Erysipelothrix rhusiopathiae. Study of 2 cases and review of the literature].

Endocarditis produced by E. rhusiopathiae is a uncommon disease. Most of the infected persons (90%) work in environments with frequent exposure to E. rhusiopathiae (butchers, fisherman). Although the clinical picture of endocarditis produced by E. rhusiopathiae is indistinguishable from other forms of subacute endocarditis, this infection has a mortality rate of 40% and a high morbidity. Microbiological diagnosis should consider the possibility of making a mistake considering that isolation of a gram-positive bacillus may represent contamination by an agent without clinical relevance. Treatment with penicillin G during 4 weeks is commonly sufficient to cure the disease.

Adult↗
PubMed1990

A monoclonal IgA in a patient with amyotrophic lateral sclerosis reacts with neurofilaments and surface antigen on neuroblastoma cells.

A 75-year-old woman had breast carcinoma, an IgA paraprotein and autopsy-proven amyotrophic lateral sclerosis. Autopsy tissues showed immune-reactive IgA within surviving motor neurons and deposits of IgA and C3 within renal glomeruli. By indirect immunofluorescence, the patient's serum contained high-titer IgA that bound to axons and to the perikarya of nerve cells in central and peripheral nervous system. The IgA paraprotein reacted with the 200 kDa, high molecular weight subunit of neurofilament protein (NFH) in Western blots of purified neurofilaments. It also reacted with dephosphorylated NFH and with NFH expressed as a fusion protein in E. coli, suggesting that the autoantibody recognized a peptide epitope. The IgA crossreacted with a surface antigen of cultured human neuroblastoma cells but mouse monoclonal antibodies to NFH did not. Absorption of the patient's serum with neurofilaments eliminated IgA binding to neuroblastoma cells, indicating that the same antibodies bound to both determinants. The IgA paraprotein seems to be an autoantibody with specificity for neurofilament protein and a cell surface component of neuronal cells; the antibody may have been important in the pathogenesis of neuronal degeneration.

Aged↗
PubMed1990

Intramedullary ependymoma of the spinal cord.

A consecutive series of 23 patients underwent operative removal of an intramedullary spinal cord ependymoma between January, 1976, and September, 1988. Thirteen women and 10 men between the age of 19 and 70 years experienced symptoms for a mean of 34 months preceding initial diagnosis. Eight patients had undergone treatment prior to tumor recurrence and referral. Mild neurological deficits were present in 22 patients on initial examination. The location of the tumors was predominantly cervical or cervicothoracic. Radiological evaluation revealed a wide spinal cord in all cases. Magnetic resonance (MR) imaging was the single most important radiological procedure. At operation, a complete removal was achieved in all patients. No patient received postoperative radiation therapy. Histological examination revealed a benign ependymoma in all cases. The follow-up period ranged from 6 to 159 months (mean 62 months) with seven patients followed for a minimum of 10 years after surgery. Fourteen patients underwent postoperative MR imaging at intervals ranging from 8 months to 10 years postoperatively. No patient has been lost to follow-up review and there were no deaths. No patient showed definite clinical or radiological evidence of tumor recurrence during the follow-up period. Recent neurological evaluation revealed functional improvement from initial preoperative clinical status in eight patients, no significant change in 12 patients, and deterioration in three patients. The data support the belief that long-term disease-free control of intramedullary spinal ependymomas with acceptable morbidity may be achieved utilizing microsurgical removal alone.

Adult↗
PubMed1989

BGP (osteocalcin, bone-Gla-protein) in involutional osteoporosis.

The role of BGP (osteocalcin) as bone marker in the study and management control of involutional osteoporosis is emphasized and the different radioimmunoassays and their limitations are commented. Our results showed significantly lower sBGP levels in osteoporotic patients compared with control group and a positive linear correlation was found between sBGP and serum alkaline phosphatase but no correlation was obtained with urinary hydroxyproline/creatinine ratio, serum tartrate-resistant acid phosphatase or bone mineral content measured by dual photon absorptiometry.

Acid Phosphatase↗