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Biomedical subjects

M Rodríguez

Publications and source records attributed to M Rodríguez.

At least 181 records · Page 10Linked to original sources
PubMed1998

Evaluation of proteolytic activity of micro-organisms isolated from dry cured ham.

In order to determine the possible contribution of micro-organisms to the ripening of meat products, 48 cocci, 18 moulds and 20 yeasts isolated from dry-cured Iberian ham were evaluated for proteolytic activity. Two specific methods were used: the ability to hydrolyse myosin in broth and, for those strains showing high activities, hydrolysis on both myofibrillar and sarcoplasmic proteins on pork slices. Moulds and cocci showed the highest proteolytic activity for myosin in broth. Both myofibrillar and sarcoplasmic proteins were recovered at lower rates from inoculated than from sterile incubated pork. The deepest changes in myofibrillar and sarcoplasmic proteins were originated by one strain each of Penicillium chrysogenum and Staphylococcus xylosus, respectively. Only small changes were observed in the concentrations of free amino acids from inoculated pork slices, except for the samples with P. chrysogenum, where there were increases in all free amino acids. Thus, P. chrysogenum makes a significant contribution to proteolysis during the ripening of dry-cured meat products.

Animals↗
PubMed1998

Cardiovascular response to hemodialysis: the effects of uremia and dialysate buffer.

Cardiovascular instability continues to be one of the primary clinical problems in hemodialysis. Acetate buffer in dialysate is one of the factors that may induce hypotension. Since uremia may have a direct effect on the regulation of the cardiovascular system, the present study was designed to investigate the separate effects of uremia and acetate hemodialysis on blood pressure in anesthesized dogs, as well as the hemodynamic parameters determined by invasive cardiovascular monitoring. Animals were separated into four groups: (1) group I, hemodialysis with acetate in controls; (2) group II, hemodialysis with acetate in uremic dogs; (3) group III, hemodialysis with bicarbonate in controls; and (4) group IV, hemodialysis with bicarbonate in uremic dogs. Acute uremia was induced by bilateral ureteral ligation and a 90-minute hemodialysis (acetate or bicarbonate) procedure was performed 72 hours later. The results obtained in this study show that, compared with dogs with normal renal function, acute uremia resulted in an elevation in mean arterial pressure (MAP; 178 +/- 13 vs. 115 +/- 23 mm Hg, P < 0.01), which was associated with an increase in cardiac index (CI) and left ventricular stroke work index (LVSWI). In these dogs, the pulmonary capillary wedge pressure (PCWP; preload) and the systemic vascular resistance index (SVRI; afterload) were not different than controls. In uremic dogs, hemodialysis with acetate, but not with bicarbonate, decreased the MAP to values similar to controls. The decrease in MAP induced by acetate hemodialysis in uremic dogs was associated with a decrease in SVRI and PCWP. These results suggest that in dogs with acute uremia, acetate hemodialysis (HD) decreases myocardial contractility that was previously increased by a direct effect of uremia. In controls, acetate produced a moderate decrease in MAP that was the result of a mild decrease in CI and SVR. Since PCWP was not significantly decreased after acetate HD, the decrease in CI can be attributed to a mild decrease in myocardial performance. In conclusion, this study in dogs suggests that uremia enhances myocardial contractility directly. Acetate hemodialysis reduces this elevated myocardial contractility to normal values.

Acetates↗
PubMed1998

The effect of a high phosphorus diet on the parathyroid cell cycle.

High extracellular phosphorus directly increases parathyroid hormone (PTH) secretion and gene transcription. The present study evaluates the effect of high phosphorus diet on the parathyroid cell cycle in rats with normal renal function. Rats were divided into two groups, receiving either a high phosphorus diet (HPD, P=1.2%) or a normal phosphorus diet (NPD, P=0.6%). The dietary calcium content was 0.6% in both diets. Rats were pair fed and sacrificed on days 0, 1, 5, 10 and 15 after initiation of the diet. The parathyroid glands were removed and parathyroid cells dispersed for evaluation of cell cycle and apoptosis by flow cytometry. Serum calcium, phosphorus, PTH and calcitriol were measured. As compared with NPD, the ingestion of a HPD resulted in an increased number of cells in the S phase of the cell cycle from day 1 to 10 (1.2+/-0.09% vs 0.6+/-0.04% for day 1, 1.2+/-0.11% vs 0.6+/-0.06% for day 5 and 1.0+/-0.09% vs 0.5+/-0.04% for day 10, P<0.01). By day 15, the percentage of cells in the S phase in NPD and HPD were not different. In the rats fed the HPD, serum PTH increased significantly from day 5 through 15 (P<0.01). Parathyroid cell apoptosis was minimal and unaffected by the diet. At day 15, the parathyroid gland size in HPD was increased by 27% as compared with NPD (P<0.05). This increase should be attributed to cell proliferation since parathyroid cell size remained unchanged. Serum calcitriol and calcium were not significantly different in the two groups. In HPD, an increase in serum phosphorus was observed only on day 1. The results show that an HPD results in the stimulation of the parathyroid cell cycle independently of changes in calcium and calcitriol.

Animals↗
PubMed1998

Measurement of parathyroid hormone in horses.

Measurement of parathyroid hormone (PTH) in horses was performed on plasma samples using 2 immunoradiometric assays: a human intact PTH assay and a rat amino-terminal PTH assay. The assays were validated by assessment of their precision, sensitivity and specificity, and also by evaluating PTH changes in the horse in response to variation in blood ionised calcium. Intra- and inter-assay variance, precision and sensitivity were similar for both human and rat assays; however, the rat assay was slightly more precise and sensitive than the human assay. Both assays detected an increase in PTH levels in the horse when blood ionised calcium was decreased and a decline in PTH concentration with hypercalcaemia. Measurement of PTH concentration in samples from healthy horses with the human assay yielded a mean (+/-s.e.) value of 31.3+/-4.1 pg/ml. When using the rat assay, PTH values were 44.1+/-5.3 pg/ml. Plasma samples held for up to 3 months at -20 degrees C did not show a significant change in PTH concentration. In conclusion, the human intact PTH and the rat amino-terminal assays detected equine PTH and can be used for measurement of this hormone in horses. Quantification of equine PTH using these assays will allow more precise diagnosis of a variety of disorders affecting mineral metabolism in horses.

Animals↗
PubMed1998

Extraintestinal salmonellosis in a general hospital (1991 to 1996): relationships between Salmonella genomic groups and clinical presentations.

Episodes of extraintestinal salmonellosis treated at a general hospital (1,522 beds) over a 6-year period (1991 to 1996) were characterized by the analysis of phenotypic and genotypic traits of Salmonella organisms and clinical data from medical reports. Extraintestinal salmonellosis accounted for 8% of all salmonellosis episodes. Fifty-two medical reports, dealing with 6 cases of typhoid fever, 32 cases of bacteremia, and 14 focal infections, were reviewed. All cases of typhoid fever except 1, 7 cases of bacteremia, and 5 focal infections were not related to any underlying disease or predisposing factors, while 25 cases of bacteremia and 9 focal infections were associated with some of these risk factors. All typhoid isolates and 65.4% of the nontyphoid isolates were susceptible to antimicrobials. Fifty-one nontyphoid strains were analyzed and assigned to 21 genomic groups, which were defined by serotype, combined ribotype, and combined randomly amplified polymorphic DNA type (each genomic group could include organisms differing in some phenotypic traits). The relationships between genomic groups and clinical presentations were traced. Organisms causing 22 episodes (17 episodes of bacteremia, 2 of pneumonia, 1 of peritonitis, 1 of pyelonephritis, and 1 of cystitis) belonged to a prevalent Salmonella enterica serotype Enteritidis genomic group, which included organisms assigned to four phage types, five biotypes, and four resistance patterns, causing infections in patients with and without risk factors. Seven other genomic groups, 4 Enteritidis groups (associated with both bacteremia and focal infections), 2 Typhimurium groups (one associated with bacteremia and the other with focal infections) and 1 Brandenburg group (associated with bacteremia) included two or more strains, and the remaining 13 genomic groups consisted of only one strain each.

Adolescent↗
PubMed1998

Time resolution for visual information processing in Parkinson's disease.

It has been suggested that a deficit in timing could be the cause of the sensory disturbances reported for Parkinson's disease. To test this hypothesis the temporal discrimination thresholds in four visual tasks were used to study 45 healthy young people, 14 healthy elderly people, and 17 patients with Parkinson's disease. In these tasks, subjects watched a computer controlled light emitting diode display and pushed a button when the visual event previously specified by the researcher was perceived. The time between successive images required to discriminate a visual detail was accurately quantified. In two of the four tasks, the time for visual processing of image sequences was longer in the elderly group than in the young group. No significant differences were found between patients with Parkinson's disease and their age matched controls for any of the four tasks. Present data show normal temporal discrimination and no slowing in the initial steps of visual processing in Parkinson's disease.

Adult↗
PubMed1998

The range of bone mineral density in healthy Canarian women by dual X-ray absorptiometry radiography and quantitative computer tomography.

Bone mass measurements play a crucial role in the diagnosis of osteoporosis. According to a World Health Organization (WHO) Working Group, osteoporosis in women can be diagnosed if the value for bone mineral density (BMD) is 2.5 or more standard deviations below the mean value of a young reference population. This definition obviously requires the availability of normal data, which should ideally be obtained locally. The objective was establish normal values of BMD in the female Canarian population, by dual X-ray absorptiometry (DXA) in the lumbar spine and the proximal femur, and by quantitative computed tomography (QCT) in the lumbar spine, and to study the correlation between the results of both techniques and the changes with age. Seven hundred forty-four Healthy Canarian women, from 20-80 yr old were examined. Measurement of bone density was performed by an Hologic QDR 1000 densitometer (DXA) in the lumbar spine and proximal femur, and by a Toshiba scanner model 600 HQ in the lumbar spine. Both methods show that the peak bone mass is achieved in the fourth decade (30-39 yr). Bone density decreases thereafter with age in the lumbar spine (r = -0.3364 DXA and r = -0.6988 for QCT) and in the femoral neck (r = -0.3988). Bone density mean values obtained by DXA are very similar to those described in Spain and in other European female populations, using the same densitometer. The correlations between both techniques (DXA and QCT) were high and statistically significant (p < 0.001 in every case). Normal values in the normal Canarian women for DXA and QCT are provided. Our results are very similar to those previously described. These two techniques have a close correlation.

Journal Article↗
PubMed1998

Nonbiocompatible hemodialysis membranes induce apoptosis in mononuclear cells: the role of G-proteins.

Mononuclear cells are activated during hemodialysis. In this study, we provide evidence that in vitro culture of mononuclear cells with Cuprophan, a nonbiocompatible hemodialysis membrane, increases the levels of protein phosphorylation in these cells as well as the expression of surface activation molecules. By contrast, culturing of mononuclear cells with AN69, a more biocompatible membrane, did not increase protein phosphorylation levels or expression of surface activation molecules in these cells. In addition, Cuprophan, but not the AN69 membrane, increased the percentage of mononuclear cell death by apoptosis. Inhibition of G-protein-mediated signal transduction decreased the apoptosis of cells cultured with the Cuprophan membrane. The GTP-binding protein involved in Cuprophan-induced apoptosis was sensitive to the ADP-ribosylating pertussis toxin (PTX). The inhibition of GTP-binding protein decreased apoptosis in the early stage of the activation-induced apoptosis, suggesting that G-proteins are implicated in the transmission of apoptosis-inducing signal(s) but do not interfere with the effector signals that mediate the late stages of apoptotic catabolism. Finally, PTX was capable of inhibiting apoptosis without affecting expression of activation molecules; thus, the inhibition of apoptosis by Cuprophan was not due to quenching of the stimulation signals, because monocytes were still able to be activated by Cuprophan despite the action of PTX. The results obtained in this study suggest that cell activation and apoptosis may be mediated by separate intracellular signals.

Acrylic Resins↗
PubMed1998

[Arterioportal fistula and hemobilia in a patient with hepatic transplant].

The case of a 36-year old male liver transplant recipient hospitalized for upper digestive hemorrhage, jaundice and pain in the right hypochondrium is herein reported. Two hepatic biopsies had been performed 60 and 7 days prior to admission. Bleeding was observed to be from the biliary tract by endoscopy and an arterioportal fistula in the right hepatic lobe by echo-doppler and arteriography was seen. Treatment with selective embolization by arteriography was satisfactory with biliary tract drainage not being required. Doppler echography was used to control the evolution of the patient.

Adult↗
PubMed1998

Ambulatory liver biopsy: complications and evolution in 264 cases.

AIM: To determine the safety and acceptance of outpatient liver biopsies. PATIENTS AND METHODS: Data from all liver biopsies were collected in a prospective way over a period of 18 months. Information was gathered on complications, evolution of patients outside the hospital and opinion relating to the test. All patients were required to previously present: platelet count > 60.000/mm3 prothrombin time within 4 seconds of control and absence of ascites or encephalopathy. Criteria for outpatient liver biopsy also included cooperative patient, a partner or friend who stayed with the patient during 12-24 hours following the test and easy access to the hospital. Out of a total of 378 biopsies, 264 (70%) were ambulatory. RESULTS: Five of the 264 outpatients were hospitalized (1.9%), due to a subcapsular hematoma in one case, persistent pain in 3 cases and sever hypotension in the other; all of them evolved favorably in the first 24 hours. Among the inpatients, 2 had complications (1.7%): one subcapsular hematoma resolved without treatment and one abdominal hemorrhage requiring transfusion. Of the ambulatory patients, 46 (18%) presented pain whilst at home, being more frequent in females than in males (30% vs 15%, p = 0.004) and in those who needed more than one attempt to obtain histological material compared with those of a single attempt (33% vs 17%; p = 0.008). Twenty four hours after the test, 83% of the patients had returned to their normal activities. Ninety five percent of the patients questioned considered that the test was not traumatic, and 88% stated a preference for liver biopsy as a day case procedure. CONCLUSIONS: Liver biopsy performed on an ambulatory basis is safe, well tolerated and acceptable by the majority of patients.

Adolescent↗
PubMed1998

[Validation of the imagamma interface for connecting gamma cameras to personal computers].

An electronic interface, imagamma, has been designed in order to link analog gamma cameras to IBM personal computers (PCs). The performance of the interface was assessed for a camera-computer system composed by a GE Maxicamera II-400T gamma camera and an IBM PC, which has a DX 80486 processor, 8 Mb RAM and a suitable acquisition and processing software. Quality control tests for gamma camera-computer systems, established by the International Atomic Energy Agency in the IAEA-TECDOC-602 for < >, were performed. The main performance characteristics of the gamma camera: intrinsic flood field uniformity, intrinsic spatial resolution and spatial linearity were tested as well as the system time performance for dynamic and gated studies. The results obtained for the camera-computer system performance parameters show a good stability. Those results concerning the dynamic characteristics of the interface are between the limits of acceptability, established for each test by the IAEA standards. We conclude that the imagamma interface has suitable performance characteristics to link analog gamma cameras to PC based computer systems in order to be used with clinical application purposes.

Evaluation Studies as Topic↗
PubMed1998

[Effect of enalaprilat on postischemic systolic and diastolic dysfunction (stunned myocardium) on the isolated rabbit heart].

The aim was to determine: 1) whether Enalaprilat (0.08 mg/kg/min) administration: a) before ischemia or b) at the beginning of reperfusion improved the postischemic systolic and diastolic dysfunction ("stunned myocardium") and attenuated the "hyperfunction" phase at the beginning of reperfusion; and 2) whether creatine kinase (CPK), and lactate dehydrogenase (LDH) activities, and lactate release are involved in the protective effects of Enalaprilat. An isolated isovolumic rabbit heart preparation was used as experimental model and subjected to 15 minutes of ischemia followed by 30 minutes of reperfusion, without (group 1), and with Enalaprilat before the ischemia (group 2) and at the beginning of reperfusion (group 3). Left ventricular developed pressure, and end diastolic pressure (diastolic stiffness) were measured and the time constant of isovolumic relaxation (t, Tau) and the ratio between +dP/dtmax and -dP/dtmax were calculated. For the determinations of lactate release and CPK and LDH activities in the perfusate, samples were taken from the coronary effluent for spectrophotometrical measurements. In comparison to the stunned group (group 1) both Enalaprilat preischemia (group 2) and postischemia (group 3) exerted a significant protective effect on the postischemic recovery of contractile state and diastolic stiffness, and attenuated the "hypercontractile" phase in both groups. However Enalaprilat failed to improve myocardial relaxation. Lactate release was also attenuated, but the enzyme activities were not modified.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1998

A recombinant protein-based enzyme immunoassay for IgM antibody to human cytomegalovirus.

The reliability of an enzyme-linked immunosorbent assay (ELISA) which used recombinant antigen to detect human cytomegalovirus IgM was studied. Serum samples from each of 283 children aged 5 +/- 2 years were studied. In all samples the anti-IgM antibodies were investigated with the ELISA techniques Enzygnost (Behring) and ETI-Cito (Sorin) which were both based on whole viral particles, and OPUS (Behring) based on recombinant antigen. Of the samples, 254 (89.4%) were negative with all three tests. The 29 remaining samples were positive with one or two of the three techniques. The diagnostic efficacy of Enzygnost, ETI-Cito and OPUS, respectively, was for sensitivity of 50%, 66.7% and 50%, and for specificity of 100%, 95.6% and 96%, respectively. The results with each of the three ELISAs did not differ widely and their diagnostic efficacy was similar. The method based on recombinant antigen was not found to be more effective than tests based on whole viral particles.

Antibodies, Viral↗