Search PubMed⌕ Search

Biomedical subjects

C Alvarez

Publications and source records attributed to C Alvarez.

At least 163 records · Page 9Linked to original sources
PubMed1994

Sources of pancreatic pathogens in acute pancreatitis in cats.

The source(s) of pancreatic pathogens is uncertain, although the colon is usually implicated. We studied whether pathogens may spread from different sites in a feline model of the disease. Acute pancreatitis was induced using a standard technique and a distinctive clinical strain of Escherichia coli as the marker bacterium. E. coli were placed in the colon, gall bladder, main pancreatic duct, or obstructed renal pelvis of control cats (no pancreatitis) and acute pancreatitis cats. Pancreases were colonized from each source, whether or not pancreatitis was present. The pancreatic colonization rate was greater in acute pancreatitis only when E. coli had been placed in the colon. In conclusion, E. coli may spread to the pancreas from different sources. The high rate of pancreatic colonization in both control and inflamed glands suggested that, clinically, bacteria may spread to the pancreas more frequently than is currently thought.

Acute Disease↗
PubMed1994

Inflammatory and phagocytic response to experimental Campylobacter jejuni infection in mice.

After intraperitoneal inoculation with Campylobacter jejuni BALB/c, Swiss and DBA mice show a peritoneal inflammatory response of different intensity. Only BALB/c mice have a strong peritoneal response. Simultaneous intraperitoneal inoculation of C. jejuni plus FeCl3 increase both inflammatory response and phagocytic activity in Swiss mice, without production of diarrhea. Some thermostable compounds of C. jejuni have a very strong chemotactic activity against peritoneal cells of mice, whereas a diffusible, thermolabile and glutaraldehyde-resistant factor has an inhibitory effect over murine peritoneal cell phagocytosis. Bactericidal activity of peritoneal cells increased after in vitro re-challenge with C. jejuni. Bacteremia is present in all the mice strains tested, but the clearance is quick in DBA and slow in BALB/c and Swiss mice. These experiments confirm that in mice, peritoneal non-specific mechanisms of defense, such as macrophages, play an important role in order to control C. jejuni infection.

Animals↗
PubMed1994

[Personality dimensions and cerebral evoked potential].

Eysenck's personality theory postulates 3 orthogonal dimensions of personality: extraversion (E), neuroticism (N) and psychoticism (P), predicting conductual and physiological predispositions to suffer mental illness. Biological bases of Eysenck's personality traits have been documented electrophysiologically. Psychoticism, the latest described dimension, is controverted, since there is some evidence of common factors with the other two. In order to assess the relation between Eysenck's dimensions and sensorial reactivity and information encoding processes we studied 20 healthy young subjects (mean age 28.5 years) with flash visual cortical evoked potentials (VEP, 3 intensities, peak to peak amplitude of III, IV-V-VI, VII components), and auditory cognitive evoked potentials (odd ball paradigm, P300 latency). There was a positive correlation between N and P dimensions (Spearman, r = 0.52), between N and VEP amplitude at high intensity (r = 0.58) and a negative correlation between E and P300 latency (r = 0.58). In short we found that P is not an independent dimension, but is related to sensorial reactivity. E dimension was related to encoding processes supporting Eysenck's observations about memory and learning differences.

Adult↗
PubMed1994

Accelerated recovery from toxic acute renal failure with thyroxin: stimulation of renal phospholipid biosynthesis.

Thyroxine (T4) seems to accelerate recovery from various forms of acute renal failure. The mechanisms of this effect are still debated. We decided to evaluate if thyroxine enhances the recovery of HgCl2 renal failure through an increment in the mitotic activity or through an increase in membrane phospholipid biosynthesis of the regenerating tubular cells. Male Wistar rats were allocated to four groups: one group received 0.4 mg/100 g BW HgCl2 SC and saline IP (HgCl2 group); the second received the toxin and 24 and 48 h after it, T4 15 micrograms/100 g BW IP (HgCl2 + T4 group); a third group received saline SC and T4 IP (T4 group), and the last group received saline SC and IP (control group). On the third day GFR was evaluated by 24-h creatinine clearance and afterward rats were sacrificed and the kidneys removed. Some of them were studied histologically, evaluating the severity of the tubular lesion using a semiquantitative score (0-4) and the mitotic index (N mitotic figures per 10 high-power fields). In the other kidneys we studied phospholipid synthesis through the incorporation of 32 P into the different renal phospholipids of the several kidney regions. The T4-treated group had a better recovery of GFR after the toxin (HgCl2 + T4: 0.44 +/- .09 vs. HgCl2: 0.23 +/- .06, p < .05). Both HgCl2-treated groups had similar lesional scores and mitotic indexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1994

Early primary tissue failure of a Labcor bioprosthesis.

A 78-year-old woman underwent re-replacement of a 19mm Labcor bioprosthesis implanted in aortic position eighteen months earlier. The rupture of the free margin of one leaflet was found at reoperation. There was no apparent cause of this rupture.

Aged↗
PubMed1994

Pancreatic interstitial pH regulation: effects of secretory stimulation.

BACKGROUND: Bicarbonate secretion by pancreatic ducts presumably releases an equivalent amount of acid into the parenchyma. The purpose of this study was to determine the effects of this acid load on pancreatic interstitial pH (pHI). In addition, we examined the relationship of pHI to changes in pancreatic blood flow (PBF), which may be important in acid disposal. METHODS: After validation of a microelectrode method for measurement of pHI in anesthetized cats, the effects of secretin (2 IU/kg intravenously) and cholecystokinin (0.08 microgram/kg intravenously) were examined. PBF was measured simultaneously by the H2 gas clearance technique. RESULTS: Secretory stimulation with secretin produced an increase in pancreatic bicarbonate secretion (146 +/- 23 microEq/15 minutes, p < 0.01). This secretion was associated with a fall in pHI from 7.36 +/- 0.02 to 7.31 +/- 0.02 (p < 0.001), which returned to baseline after 25 minutes. There was an accompanying increase in PBF from 118 +/- 32 to 148 +/- 35 ml/min/100 gm (p < 0.01). In contrast, stimulation with cholecystokinin only slightly increased pancreatic secretion (49 +/- 19 microliters/15 minutes) and had no significant effects on pH or blood flow. CONCLUSIONS: These results suggest that pancreatic secretion of bicarbonate, but not protein, releases H+ into the interstitium, an acid tide comparable to the alkaline tide during acid secretion by the stomach. This interstitial acidosis was accompanied by an increase in PBF. The increase in blood flow may be important in pH homeostasis, contributing to the disposal of this acid.

Animals↗
PubMed1993

Immunocytochemical evidence of well-developed dopaminergic and noradrenergic innervations in the frontal cerebral cortex of human fetuses at midgestation.

The catecholaminergic (CA) innervation of the frontal lobe was visualized in 20- to 24-week-old human fetuses with immunocytochemical techniques, by use of antibodies raised against three synthetic enzymes of the CA pathway, tyrosine-hydroxylase (TH), dopamine-beta-hydroxylase (DBH), and phenylethanolamine-N-methyltransferase (PNMT). DBH-like immunoreactivity (IR) was probably labeling the noradrenergic (NA) fibers and terminals in the cerebral cortex since no PNMT-IR fibers were detected. In double-labeling TH-DBH experiments, 92-95% of the DBH-IR afferents were not labeled with TH antibodies, indicating that TH-like immunoreactivity (TH-IR) was found primarily in dopaminergic (DA) fibers. Although cortical layering had not yet occurred at this stage, the widespread CA innervation observed in the different areas and layers of the fetal frontal cortex was comparable to that previously described in the adult (Gaspar, Berger, Febvret, Vigny, and Henry: J. Comp. Neurol. 279:249-271, '89). At midgestation, the distribution of CA innervation was region and laminar specific: 1) The densest dopaminergic innervation in the cerebral cortex was located caudal to the genu of the corpus callosum: TH-IR fibers were abundant throughout all layers, from the medial telencephalon (future cingulate) to the dorsal areas (presumed motor cortices) and the lateral insular areas; 2) TH-IR fibers were less dense in the rostral prefrontal cortical anlage; 3) DBH-IR noradrenergic afferents were less numerous than the dopaminergic ones in all the cortical areas studied; 4) in all areas, the highest amount of TH and DBH-IR terminals was found in the upper subplate and in the lower part of the cortical plate, followed by the molecular layer and the intermediate zone. The deep subplate exhibited a lower number of positive fibers but contained TH-IR cell bodies. The presence of dense CA innervation in the immature cortical anlage of the human frontal lobe does not exclude a reorganization of DA and NA innervations within the different cortical layers and areas during the protracted pre- and postnatal period of development.

Antibodies, Monoclonal↗
PubMed1993

Neurochemical development of the hippocampal region in the fetal rhesus monkey. I. Early appearance of peptides, calcium-binding proteins, DARPP-32, and monoamine innervation in the entorhinal cortex during the first half of gestation (E47 to E90).

Although the entorhinal cortex is a key structure connecting the hippocampal formation with the rest of the cerebral cortex, little is known about its early chemoanatomical development in primates. In the present study, a cytoarchitectonic analysis and immunocytochemical detection of somatostatin, neurotensin, parvalbumin, calbindin-D 28K, DARPP-32, as well as tyrosine hydroxylase, dopamine-beta-hydroxylase, and serotonin, were carried out on serial sections of the entorhinal cortex of six rhesus monkey fetuses aged E47 to E90 (gestation period 165 days). At E56 the cortical plate of the entorhinal cortex already exhibited a sublamination; at E64 the lamina dissecans was partly formed, allowing the emergence of the lamina principalis externa and interna, and at E83 most of the regional and laminar subdivisions characteristic of the adult cortex could be identified, except for the rhinal sulcus restricted to a small dimple. The neurochemical development paralleled the early cytoarchitectonic differentiation, both largely preceding that of the neighboring cortical areas. The somatostatin-like immunoreactive innervation, first detected at E56, was very dense as early as E64 and displayed by E83 a laminar distribution similar to that found in the adult. Labeled neurons indicated an intrinsic origin for this innervation but an extrinsic connection might be present as labeled fibers in the subplate of the entorhinal cortex were in continuity with positive fibers in the intermediate zone of the hippocampal formation. A faint neurotensin-like immunoreactivity first detected at E64 became prominent at E83 in the entorhinal cortex but stopped abruptly at the anlage of the rhinal sulcus. The lack of neurotensin-labeled neurons contrasted with their presence in other parts of the hippocampal region and suggested a precocious extrinsic connection. Only rare parvalbumin-LIR neurons were detected at midgestation, whereas calbindin-D 28K was expressed from E47 on in Cajal-Retzius cells and from E56 on in various types of neurons in the cortical plate and subplate. Most characteristic was a category of medium-sized, deeply stained calbindin-LIR neurons, present only in the lamina principalis externa and possibly corresponding to the population of large neurons described by Kostovic et al. (1990, Soc Neurosci Abstr 16:846) in early developing entorhinal cortex of human fetuses. These and probably other neurons were also DARPP-32-positive, suggesting the possibility of an early dopaminergic regulation. Indeed, the monoaminergic innervation of the entorhinal cortex was detected from E56 on and gradually increased in density, displaying areal and laminar differences in the distribution of the dopaminergic, noradrenergic, and serotoninergic afferents.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Alpha 2-adrenergic blockade prevents hyperglycemia and hepatic glutathione depletion in nickel-injected rats.

To study the involvement of the adrenergic system in nickel-induced hyperglycemia and hepatic glutathione depletion in rats, several adrenergic antagonists (phentolamine, prazosin, yohimbine, and propranolol) were administered in a single ip injection before acute nickel treatment (ip injection). Moreover, the effects of nickel on adrenalectomized rats were investigated. Hyperglycemia was suppressed by either alpha-antagonist phentolamine or alpha 2-antagonist yohimbine. Such blockade coincided with the prevention of the hypoinsulinemic response to nickel, which occurred simultaneously to hyperglycemia. Nickel-induced hyperglucagonemia remained almost unaltered by pretreatment with adrenergic antagonists. In adrenalectomized animals treated with nickel, hyperglycemia was attenuated, whereas hypoinsulinemia still persisted. Therefore, catecholamines seemed to participate in nickel-induced hyperglycemia, directly, i.e., stimulating glucose output from liver, or by modulating insulin secretion throughout alpha 2-adrenoreceptor stimulation in pancreatic islets. Hepatic glutathione depletion caused by nickel was prevented by either alpha 1-antagonist prazosin or alpha 2-antagonist yohimbine. Interestingly, adrenalectomy did not alter the drop in hepatic GSH induced by nickel treatment. Overall results suggest that the effects observed after acute nickel exposure were caused by a combined action of catecholamines released from the adrenal glands and those released at the efferent nerves. Such events have been found to be mediated by alpha 2-adrenergic receptors.

Adrenergic alpha-Antagonists↗
PubMed1993

Cost-benefit analysis of the work-up for pancreatic cancer.

We reviewed the records of 126 patients with pancreatic cancer to assess the value of diagnostic tests. The most commonly performed studies were computed tomography (CT) (97% of patients), endoscopic retrograde cholangiopancreatography (ERCP) (44%), and fine-needle aspiration (FNA) (41%). Of 34 patients who were found to have a mass in the body or tail of the pancreas on CT, 13 underwent ERCP; the results found by ERCP did not affect the management of the patients, whereas the results of FNA in 12 patients eliminated the need for operation. Of 14 patients with suspected metastases as evidenced by CT, the results of 3 ERCPs had no impact, whereas 5 of 7 patients who had FNAs avoided operation. Of five patients with normal results on CT, three had an ERCP that identified tumor. Of 26 patients with atypical CTs, the results of 12 of 16 ERCPs and 3 of 5 FNAs confirmed cancer. In contrast, in 48 patients with a mass in the head of the pancreas and biliary dilatation, ERCP did not alter the patients' management; only 3 of 14 patients who had FNAs avoided operation. Thus, the results of ERCP rarely altered the management of the patient when the CT showed a mass but was useful when the scan was normal or atypical. FNA was helpful in patients with cancer in the body or tail of the pancreas or with suspected metastases and in confirming the diagnosis when the CT was inconclusive.

Adenocarcinoma↗
PubMed1993

Differential effects of experimentally induced chronic pancreatitis on neuropeptide immunoreactivities in the feline pancreas.

The distribution and concentration of calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), and gastrin-releasing peptide (GRP) immunoreactivities in the pancreas of cats with experimentally induced chronic pancreatitis and of age- and sex-matched controls were investigated. By narrowing the main pancreatic duct between the head and the body to approximately 25% of its normal diameter, we induced within 5 weeks chronic pancreatitis restricted to the body and tail. In control animals, peptide immunoreactive nerves were distributed to the islets, acini, and ducts; the latter were predominantly innervated by fibers immunoreactive for NPY, VIP, or CGRP. The vasculature received an abundant supply of NPY-, CGRP-, and, to a lesser extent, SP-containing axons. Within intrapancreatic ganglia, peptide immunoreactivities were identified in fibers and ganglion cells, with the exception of CGRP and SP immunostaining, which could be visualized only in fibers. In animals with chronic pancreatitis, the innervation pattern of each peptidergic system was comparable to that described in controls. However, there was a remarkable increase in the density and staining intensity of VIP and NPY immunoreactive fibers in the exocrine parenchyma and fibrous septa of the body and tail, where chronic pancreatitis developed. Fibers immunoreactive for CGRP and SP also were moderately denser than in controls, whereas those containing GRP immunoreactivity did not show any detectable changes. In addition, a marked increase of the immunostaining for VIP and, to a much lesser extent, for NPY and GRP, was observed in neurites supplying the head of the pancreas, which appeared devoid of histologically detectable pathological alterations. Radioimmunoassay analysis confirmed the immunohistochemical observations. The increased density of distinct peptidergic nerves in the pancreas with induced chronic pancreatitis might be the result of compensatory phenomena in response to the inflammatory process.

Animals↗
PubMed1993

A prospective study of stroke in young adults in Cantabria, Spain.

BACKGROUND AND PURPOSE: The aim of this study was to determine the incidence, type, and prognosis of stroke in young adults in Cantabria, Spain. METHODS: We investigated prospectively all patients aged 50 years or below who were admitted with the diagnosis of a stroke to the University Hospital "Marqués de Valdecilla" from April 1, 1986, to March 31, 1988. This is the main hospital of the region to which all patients with neurological problems are referred. These patients underwent a complete clinical and laboratory assessment for stroke and had 1-year mean follow-up. RESULTS: The total series included 81 patients. The annual age-specific crude incidence rates of stroke were 17.3 and 10.4 per 100,000 for males and females, respectively. Twenty-four patients (30%) were diagnosed as having nonembolic cerebral infarction, 14 (17%) embolic cerebral infarction, 20 (25%) subarachnoid hemorrhage, 22 (27%) spontaneous cerebral hemorrhage, and one case (1%) cerebral venous thrombosis. Eighteen patients (22%) died within 30 days of the cerebrovascular event, and two others died during the follow-up period. Seventy-nine percent of the survivors recovered and were completely self-sufficient. CONCLUSIONS: The incidence of stroke in the young found in Cantabria is comparable with that in previous studies. The initial hospital mortality was not negligible, but the prognosis among the survivors was favorable.

Adolescent↗
PubMed1993

[Invasive bronchopulmonary aspergillosis treated with itraconazole in a patient with acute leukemia].

A case of invasive broncopulmonar aspergillosis caused by Aspergillus terreus successfully treated with itraconazole is reported in a patient undergoing autologous bone marrow transplantation for acute lymphoblastic leukaemia. Although the patient was on prophylaxis with fluconazole and she did not respond to amphotericin B, there was an excellent response to itraconazole which allowed the transplant without any Aspergillus infection during both the transplant and the post-transplant periods. Due to its oral administration, good tolerance and low toxicity, itraconazole is a promising drug for the treatment of invasive broncopulmonar aspergillosis.

Agranulocytosis↗
PubMed1993

[Type I familial pseudohypoparathyroidism: clinical and hormonal study].

Pseudohypoparathyroidism is a rare disease characterized by a target tissue resistance to the action of the parathyroid hormone (PTH). Frequently, others hormonal disorders can be associated. We report a family with pseudohypoparathyroidism type I, and discuss the clinical-hormonal alterations founded; it is emphasized that while there were no phenotypical differences among the family members; from the hormonal features point of view, some differences do exist, and several degrees of peripheral resistance were noted.

Adult↗
PubMed1993

[The treatment of the Guillain-Barré syndrome in childhood by plasmapheresis].

We have performed 18 plasmapheresis [correction of plasma exchange] sessions in a group of 5 patients diagnosed as having Guillain-Barré Syndrome. These patients were diagnosed according to clinical, analytical and electromyographic criteria. In three patients we observed an obvious clinical improvement during the treatment. In one of the patients there was no appreciable evolution. This patient suffered from acute lymphocytic leukemia. We were unable to evaluate the remaining patient since this child underwent posthypoxic encephalopathy secondary to cardiac arrest. On the basis of the results obtained, we advocate the treatment of this polyneuropathy by plasmapheresis [correction of plasma exchange].

Child↗
PubMed1993

[Changes in ethical attitudes during medical studies].

The aim of this work was to explore the attitude changes towards ethico-medical issues in medical students as they went through medical school. A personal standardized questionnaire containing 14 closed and direct questions was applied to 27 freshmen, 38 interns and 14 post graduates. The most outstanding differences in ethical attitudes occurred between first year students and the older groups. The younger students adhered to ethical principles, valued justice towards patients and moral integrity in physicians. The older students and post graduates emphasized the professional role of physicians and preferred institutional ethical regulations over public control. They also considered more valuable therapeutic efficiency and paternal attitudes towards patients as well as social prestige and economical rewards. We conclude that there is a progressive erosion of humanistic principles along the medical studies, that are substituted by a model of professional competence, social recognition and internal ethical control.

Attitude of Health Personnel↗
PubMed1993

Nickel effects on hepatic amino acids.

Female Wistar rats were treated with nickel (single i.p. injection of 6 mg Ni(II)/kg body weight) and twenty amino acids and glutathione (GSH) concentrations were determined in liver 90 minutes later. Hepatic GSH content dramatically diminished after nickel injection. Glycine and glutamate levels, precursor amino acids of GSH, were not affected by nickel treatment, whereas cysteine level, the third precursor, was drastically increased in comparison with control rats. These findings showed that hepatic GSH depletion, caused by acute nickel exposure, was not due to a reduction in the availability of precursor amino acids. Nickel treatment also induced a 2-fold increase in phenylalanine and a decrease in taurine to one fifth. Therefore, the role of taurine in protecting membranes was clearly jeopardized in liver after nickel exposure, which could account for some of the toxicologic actions of this metal. However, further research is needed to explore such suggestion.

Amino Acids↗