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Biomedical subjects

M Prieto

Publications and source records attributed to M Prieto.

At least 91 records · Page 5Linked to original sources
PubMed1998

Warthin-like tumor of the thyroid: a papillary carcinoma with mitochondrion-rich cells and abundant lymphoid stroma. A case report.

Papillary carcinoma is the most common form of thyroid carcinoma and, generally, it has a more favorable prognosis than other carcinoma types, although diverse variants or subtypes have been described, some of which appear to have a less favorable prognosis. Recently, a new variant, the so-called "Warthin-like tumor" or "tall-cell variant with extensive lymphocytic infiltration of papillary thyroid carcinoma" with behavior similar to the usual papillary carcinoma, has been described. We present a case with the cytohistological pattern of "Warthin-like tumor" of the thyroid. Immunohistochemistry revealed reactivity at the epithelium lining papillae for antimitochondrial 113-I antibody and also membranous positivity for CD15 (Leu M1). Lymphoid stroma showed an immunoprofile similar to chronic lymphocytic thyroiditis. These findings point to the consideration of "Warthin-like tumor" as being a hybrid neoplasm between the tall-cell variant and oxyphilic papillary carcinoma associated to a lymphoid-rich stroma.

Adenolymphoma↗
PubMed1998

Liver transplantation in hepatitis C. A Spanish multi-centre experience.

OBJECTIVE: The purpose of this retrospective survey was to determine the prevalence and outcome of hepatitis C virus (HCV) infection in cirrhotic patients undergoing liver transplantation (OLT) in Spain in 1992. METHODS: Post-OLT HCV infection was defined by anti-HCV (second-generation ELISA) and/or PCR. Patients were divided into groups A (HCV-positive pre-OLT: n = 124, 46%) and B (HCV-negative pre-OLT: n = 145, 54%). RESULTS: HCV infection was more prevalent in patients originally diagnosed as having non-A non-B cirrhosis (97%) and cryptogenic cirrhosis (79%) than in patients with cholestatic or metabolic diseases. Group A patients were older (53.3+/-7.9 versus 47.6+/-9.7; P< 0.05) and had a higher prevalence of hepatocellular carcinoma (22% versus 4%, P< 0.05). Post-OLT HCV infection was 99% in group A versus 4% in group B (P< 0.05). Histological hepatitis developed in 39% (66% in group A versus 14% in group B, P< 0.05) with similar follow-up. Chronic rejection occurred in 6% (3% in group A versus 8.5% in group B, P= 0.07). Retransplantation rate (overall 8%) and two-year patient survival did not differ between groups (79% versus 72%). Graft survival was higher in group A (74% versus 65% at 2 years, P= 0.04). CONCLUSIONS: HCV-cirrhosis represented the most frequent indication for OLT in Spain in 1992. While HCV recurrence was universal, de novo acquisition was rare. HCV accounted for most post-OLT hepatitis (87%), but was not associated with chronic rejection, nor with a higher retransplantation rate. Patient survival was not different in HCV patients compared to a control group after a follow-up of 2-3 years. Therefore, at present, HCV-cirrhosis is an acceptable indication for OLT.

Adolescent↗
PubMed1998

Neovascularization by cardiomyoplasty.

UNLABELLED: Nowadays cardiomyoplasty is used in cases of cardiac insufficiency as an alternative to cardiac transplant for patients with very developed ischemic cardiopathy, refractory to pharmacological treatment and without possibility of revascularization by using conventional techniques. OBJECTIVES: Our Cardiovascular Research Group has proposed as an objective, the detection of any possible myocardial neovascularization through the muscle used for cardiomyoplasty. In the case that there are new blood vessels to the diseased myocardium through the latissimus dorsi muscle flap in which it is wrapped and which aids it mechanically, it would be possible to confirm the working hypothesis that cardiomyoplasty not only improves the cardiocirculatory function mechanically but also facilitates a better blood flow to the ischemic myocardium. MATERIALS AND METHODS: The cardiomyoplasty technique is described using an experimental model of myocardial ischemia. The vascular cast is achieved by injecting methacrylate simultaneously into both the coronary tree and the wide dorsal muscle. In 15 experiments the connections between the coronary vascular system and the vascular structure of the latissimus dorsil muscle flap are demonstrated by several methods. CONCLUSIONS: We have demonstrated that cardiomyoplasty, as well as improving ventricular function, favours the revascularization of the myocardium. Cardiomyoplasty could be indicated for cases of ischemic cardiopathy in patients in whom it is not possible to perform direct revacularization using conventional methods.

Animals↗
PubMed1998

Integrity of the pericardium. Its beneficial effects on the protection of the right ventricle in the presence of acute pulmonary hypertension.

UNLABELLED: After cardiac transplant (CT), the right ventricle can be subject to an acute pressure overload, especially in cases where there is a pre-existing severe pulmonary hypertension. OBJECTIVES: To determine the maximum tolerance of the right ventricle (MxTRV) when faced with acute pressure overload. To study the function of both ventricles of the healthy heart (donor) when faced with different degrees of pulmonary hypertension. To detect possible interactions between the ventricles in the absence of the pericardium to approximate the experimental model to the clinical model of CT. METHODS: The pulmonary artery is progressively constrained in an experimental model until biventricular failure is detected. This experiment is performed in two different situations: with and without pericardial integrity. RESULTS: When pericardial integrity is maintained the MxTRV faced with a pressure overload is 73.2+/-8.56 mmHg. When this pressure is exceeded there is a circulatory collapse with a sharp fall in the cardiac output and in the aortic pressure. However, when pericardectomy is performed (model similar to CT), only 52+/-6.71 mmHg is tolerated (p< 0.001). CONCLUSIONS: With the pericardium open, as in CT, the maximum pressure that the right ventricle can support is significantly less than with the pericardium closed. The pericardium has a positive effect in protecting the systolic ventricular interaction.

Acute Disease↗
PubMed1997

PSA-NCAM and B-50/GAP-43 are coexpressed by specific neuronal systems of the adult rat mediobasal hypothalamus that exhibit remarkable capacities for morphological plasticity.

The present study was designed to determine whether the mediobasal hypothalamus of adult rats contains neurons that continue to coexpress the highly polysialylated neural cell adhesion molecule (PSA-NCAM) and B-50/GAP-43, two proteins coexpressed by virtually all of the neurons of the fetal and neonatal rat central nervous system. Confocal laser scanning microscopy combined with double- or triple-fluorescence immunostaining was used to identify the hypothalamic neurons that express high levels of both PSA-NCAM and B-50/GAP-43 and to study the possible modifications of their morphological organization following a surgical lesion through the mediobasal hypothalamus. In intact animals, PSA-NCAM and B-50/GAP-43 were found to be colocalized within numerous fibers projecting throughout the external layer of the median eminence that were immunoreactive for either gamma-aminobutyric acid (GABA) or tyrosine hydroxylase (TH). Three to 30 days after a lesion through this region, numerous regenerating axonal sprouts, triple-immunostained for PSA-NCAM, B-50/GAP-43, and either GABA or TH, were detected along the ventricular surface of, and throughout the perivascular layer of, the median eminence. Surprisingly, high levels of PSA-NCAM and B-50/GAP-43 were also associated with numerous supraependymal neurons that exhibited long ramified processes and were immunoreactive for GABA but TH-negative. The use of the proliferation marker, 3H-thymidine, further indicated that the emergence of such supraependymal neurons after median eminence lesion was not related to the proliferation of preexisting quiescent cells. These data indicate that the mediobasal hypothalamus of the adult rat contains two neuronal systems, in which the continued coexpression of PSA-NCAM and B-50/GAP-43 is related to remarkable capacities for postlesional, morphological plasticity.

Animals↗
PubMed1997

Bronchoesophageal fistula secondary to aspiration of tongue adhesion button in a child with glossoptosis.

A newborn boy with obstructive apnea secondary to glossoptosis was treated by securing his tongue to his lower lip. Soon after, the button that served for posterior fixation became detached and was thought to have been evacuated via the digestive tract. Twenty-two months later the infant presented with pneumonia involving the right lower lobe and hemoptysis, causing an acute respiratory distress syndrome (ARDS). After mechanical ventilation was started marked gastric distention was observed. Esophagography and bronchography revealed a fistula between the right main stem bronchus and the esophagus. During surgical repair the plastic fixation button was found in the bronchial orifice of the fistula. Despite surgical correction of the fistula the child died of refractory respiratory failure.

Bronchi↗
PubMed1997

Hyperlipidemia in liver transplant recipients: prevalence and risk factors.

Hyperlipidemia is common in transplant patients. Although a causal relationship to the use of cyclosporine is accepted, additional risk factors are as yet unidentified. Eighty-five liver transplant recipients treated with standard triple immunosuppression with a survival of at least 6 months were evaluated. Pretransplantation and posttransplantation variables were analyzed as predictive factors of posttransplantation hyperlipidemia. Serum cholesterol and triglyceride levels were considered elevated if they were > 250 mg/dL and > 150 mg/dL, respectively. Before and after transplantation, hyperlipidemia occurred in 8% (95% confidence interval [CI], 3% to 16%) and 66% (95% CI, 55% to 76%), respectively. After transplantation, 47% (95% CI, 36% to 58%) of the patients had isolated high triglyceride levels, 12% (95% CI, 6% to 21%) had both elevated cholesterol and triglyceride levels, and 7% (95% CI, 3% to 15%) had isolated elevated cholesterol levels. Hypertriglyceridemia occurred early after transplantation (67% by first month) and persisted nearly unchanged throughout the first year. In contrast, cholesterol levels increased with time (5%, 13%, and 27% at 1, 3, and 6 months, respectively). In univariate analysis, factors predictive of hypercholesterolemia included female sex, pretransplantation cholestatic liver disease, pretransplantation cholesterol levels > 141 mg/dL, and > 3 methylprednisolone "boluses." In multivariate analysis, only a pretransplantation cholesterol level of > 141 mg/dL (odds ratio [OR], 5.5; 95% CI, 1.4 to 21) was an independent risk factor. Risk factors associated with hypertriglyceridemia included pretransplantation hepatocellular liver disease (OR, 6.8; 95% CI, 1.2 to 40) and posttransplantation renal dysfunction (OR, 5.4; 95% CI, 1.9 to 15.4). Hyperlipidemia is a frequent finding in liver transplant recipients, and hypertriglyceridemia is the most common abnormality. Hypertriglyceridemia can be predicted on the basis of pretransplant hepatocellular disease and posttransplant renal dysfunction. Pretransplant serum cholesterol level is an independent risk factor for posttransplant hypercholesterolemia.

Adult↗
PubMed1997

Persistent cortical blindness after cyclosporine leukoencephalopathy.

Cyclosporine A (CyA)-related cortical blindness is an uncommon complication of CyA therapy in patients undergoing liver transplantation. Characteristically, neurological symptoms associated with CyA treatment usually regress after cyclosporine withdrawal. We present a case of a liver transplant recipient in whom discontinuation of CyA therapy has resulted in only partial clinical improvement, and cortical blindness remains after 1 year of follow-up. The evolution of cerebral magnetic resonance imaging (MRI) findings over time in this form of CyA leukoencephalopathy is also described.

Blindness, Cortical↗
PubMed1997

Dehydroergosterol structural organization in aqueous medium and in a model system of membranes.

The aggregation of delta 5,7,9(11),22-ergostatetraen-3 beta-ol (dehydroergosterol or DHE), a fluorescent analog of cholesterol, was studied by photophysical techniques. It was concluded that the aqueous dispersions of DHE consist of strongly fluorescent microcrystals, and no evidence for self-quenching in micellar-type aggregates was found. The organization of DHE in model systems of membranes (phospholipid vesicles) is strongly dependent on the vesicle type. In small unilamellar vesicles, no evidence for aggregation is obtained, and the fluorescence anisotropy is rationalized on the basis of a random distribution of fluorophores. On the contrary, in large unilamellar vesicles (LUVs), a steeper concentration depolarization was observed. To explain this, a model that takes into account transbilayer dimer formation was derived. This was further confirmed from observation of excitonic absorption bands of 22-(N-7-nitrobenz-2-oxa-1,3-diazol-4-yl-amino)-23,24-bisnor- 5-cholen-3 beta-ol (NBD-cholesterol) in LUV, which disappear upon sonication. It is concluded that, in agreement with recent works, sterol aggregation is a very efficient process in large vesicles (and probably in natural membranes), even at very low concentrations (approximately 5 mol%).

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1997

Complete androgen insensitivity syndrome: clinical and anatomopathological findings in 23 patients.

Complete Androgen Insensitivity Syndrome (CAIS) is a type of Male Pseudohermaphroditism due to a defect in the androgen receptor which is a DNA-binding, transcription-regulating protein whose properties are induced on androgen binding. This defect is caused by mutations of a gene localized in Xq11-12. The objective of this study is the description of the clinical and pathological features of patients with female phenotype, karyotype 46, XY and diagnosis of CAIS. They were referred to Medical Genetic Unit of University of Zulia, Maracaibo, Venezuela, between 1971-1995. The diagnostic criteria and clinical and pathological findings are reviewed. Twenty-three patients fulfilled the diagnostic criteria. Most of patients were 13 years old or older (postpuberal). The main reasons for consultation were: primary amenorrhea, inguinal hernia, familial history of CAIS and fusion of labia minora. Seventeen patients from 5 families were diagnosed with CAIS and only one per family in 6 families. All patients showed a female general phenotype with unambiguously female external genitalia. Gonadal localization (right/left) was as follows: abdominal/abdominal: 65%; abdominal/inguinal: 26%; inguinal/abdominal: 9%. Histologic features of gonads were similar to those in cryptorchid testes of otherwise normal males. There was no evidence of development of gonadal neoplasia. The patients reported here provide a remarkable opportunity to study the molecular genetic characterization that can serve as a primary tool for diagnosis and subsequent therapy.

Adolescent↗
PubMed1997

Treatment of chronic hepatitis C with interferon-alpha. Clinical histological and virological implications.

OBJECTIVE: to identify pretreatment predictive factors of long-term biochemical and virological response to interferon-alpha in chronic hepatitis C and to determine the effects of a second course of interferon-alpha in patients who responded but relapsed after interferon withdrawal. DESIGN: retrospective analysis. SETTING: outpatient liver clinic of a tertiary hospital in Spain. PATIENTS: 112 patients with chronic hepatitis C were treated with recombinant interferon-alpha (3 MU three times a week for 6 months). Twenty-four patients who responded but relapsed after interferon withdrawal were treated with a second course of interferon (3 MU three times a week for 12 months). RESULTS: seventy-two patients were non-responders (64%), 11 patients had a sustained response (10%) and 29 patients responded but relapsed after interferon withdrawal (26%). Five (25%) of the 24 patients who relapsed and were treated with a second course of interferon experienced a sustained response (mean follow-up: 10 months). By multivariate analysis, four pretreatment variables were found to be predictive of a complete response: age < 40 years (p = 0.0004), history of IVDA (p = 0.001), low serum levels (p = 0.013), and genotype 3 (p = 0.01). Two variables were found to be predictive of a sustained response: short duration of HCV infection (p = 0.09) and genotype 3 (p = 0.01). Sustained responders appeared to have lower HCV-RNA levels than those with complete response who relapsed and non-responders. HCV viremia levels were not associated with the severity of liver histology, duration of disease or the source of hepatitis. CONCLUSIONS: in the present study a low sustained response rate was observed using a standard interferon-alpha regimen (3 MU three times a week for 6 months). The sustained response rate increased slightly with a second course of interferon-alpha (3 MU three times a week for 12 months) in patients with a complete response who relapsed after interferon withdrawal. Sustained response is related to viral genotype and duration of HCV infection.

Adolescent↗
PubMed1996

The transverse location of the fluorescent probe trans-parinaric acid in lipid bilayers.

The transverse location of trans-parinaric acid in spherical vesicles made up from dipalmitoylphosphatidylcholine has been investigated by the differential quenching of the probe fluorescence by 5- and 16-doxylstearic acid derivatives. The quenching data are interpreted in terms of a local fluorophore concentration factor. In this way it was found that the polyene of t-PnA is located within the inner part of the bilayer (presumably aligned with the bilayer lipids), both in the gel and in the liquid crystalline phases.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1996

Resonance energy transfer in a model system of membranes: application to gel and liquid crystalline phases.

Resonance energy transfer between octadecyl rhodamine B (donor) and 1,1',3,3,3',3'-hexamethylindotricarbocyanine (acceptor) was studied in a model system of membranes (large unilamellar vesicles of dipalmitoylphosphatidylcholine), using both steady-state and time-resolved techniques. In the fluid phase (temperature = 50 degrees C) the decay law and the steady-state theoretical curve for energy transfer in two dimensions are verified. In the gel phase (temperature = 25 degrees C) an apparent reduction of dimensionality is observed, which is explained on the basis of probe segregation to the defect lines (grain boundaries). An estimation of the domain size from the model recovered linear probe concentrations is approximately 1750-2000 lipid molecules. In both phases, the existence of a fractal geometry was ruled out.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1996

[Pregnancy, breast cancer and tumor infarction].

Breast cancer is infrequently associated with pregnancy. However, such cases often pose diagnostic and treatment problems. The infarction of breast lesions is likewise uncommon, and generally hinders intraoperative morphologic diagnosis. A 33-year-old woman in the 37th week of pregnancy presented with a breast tumoration of progressively increasing size and associating mastalgia. Following fine-needle aspiration and trut-cut biopsy with posterior amplified tumorectomy and axillary dissection, a ductal neoplasm was identified with an infarction affecting 90% of the tumoral surface. The where no axillary adenopathies, and the patient was estrogen receptor-negative. An analysis is made of this rare association of pregnancy and infarcted breast cancer, with an evaluation of the role of fine-needle aspiration and/or gestation may play in the occurrence of tumor infarction.

Adult↗
PubMed1996

-Somatosensory evoked potentials by acupunctural stimulus and cortical functional projection.

We studied the somatosenory evoked potentials elicited by punctual bipolar stimulation of acupunctural points, with great and little primary sensory cortex representation. We found that different quality signal was obtained, apparently related with the extent of such cortical representation, wich indicate a possible important role of the cortex on the repetitive somatosensory afference.

Acupuncture Points↗
PubMed1995

Filipin fluorescence quenching by spin-labeled probes: studies in aqueous solution and in a membrane model system.

A detailed photophysical study of the fluorescence quenching (transient and steady state) of the macrolide antibiotic filipin by nitroxide-substituted fatty acids and a cholesterol derivative was carried out, aimed at determining its transverse position in a model system of membranes (multilamellar vesicles of dipalmitoylphosphatidylcholine). Filipin partitions efficiently into membranes (Kp = (5.0 +/- 1.0).10(3), 20 degrees C) and it was concluded that the antibiotic is buried in the membrane, away from the lipid-water interface. In addition, information on the organization of the quenchers was also obtained. The 5-nitroxide derivative of the fatty acid is essentially randomly distributed, while the 16-nitroxide is aggregated at concentrations higher than approximately 5% molar. For the cholesterol compound the results point to a phase separation at concentrations higher than 3% molar (below this limit concentration filipin associates with the derivatized sterol with KA = 20 M-1, assuming a 1:1 interaction). We propose that this phase separation and the aggregation state of filipin in the aqueous solution may be key processes in the antibiotic mode of action. A systematic and general approach to fluorescence quenching data analysis in complex (e.g., biochemical) systems is also presented.

1,2-Dipalmitoylphosphatidylcholine↗