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Biomedical subjects

A Alvarez

Publications and source records attributed to A Alvarez.

At least 163 records · Page 9Linked to original sources
PubMed1997

[Scheduled biliary surgery and antibiotic prophylaxis. Is its use always justified?].

AIM: Evaluate the need to give prophylactic antibiotic therapy in patients that undergo elective surgery for cholelithiasis. METHODS: Prospective study in 35 patients the underwent surgery for cholelithiasis, without infectious risk factors. All of them, the hemocultives, endotoxin and Tumor Necrosis Factor has been evaluated along the surgical process. RESULTS: The hemocultives were in all the patients negatives. The levels of Tumor Necrosis Factor decreased along the surgical process, without modifications of endotoxin levels. There were no significant differences in either of the points of the analysis. CONCLUSIONS: Biliary surgery in patients that undergo elective surgery for cholelithiasis, without infectious risk factors, is a clean surgery, and so, in this patients is not indicated systematically an antibiotic prophylaxis.

Antibiotic Prophylaxis↗
PubMed1997

Predicting the fear of assault at school and while going to and from school in an adolescent population.

Recent research investigating the fear of crime has shown that when crime and behavior-specific measures of fear are utilized, the young are more likely than the elderly to be the most fearful. Research investigating the etiology of fear within adolescent populations, however, remains very limited. Using a sample of over 10,000 junior high and high school students from a supplement to the National Crime Victimization Survey, this paper examines the factors contributing to students' fear of assault both at school and while going to and from school. Results indicate that recent victimization experiences, the presence of a violent subculture at the school (e.g., gang presence and attacks on teachers) and availability of drugs/alcohol were related to fear in both contexts. The predictability of fear from individual characteristics, however, was context specific. Contrary to findings from earlier research, it was found that young females were not more fearful than their male counterparts in all contexts. While they were more fearful of an attack while going to and from school, there were no differences in fear levels while at school between males and females after controlling for other environmental and experiential factors. Conclusions largely support the contention that fear is a rational calculation based on objective criteria. Moreover, results underscore the need for more specificity when operationalizing the context and content of fearfulness.

Adolescent↗
PubMed1997

[Patients with human immunodeficiency virus admitted to the emergency service of a general hospital].

BACKGROUND: The description of the demographic, toxicologic, immunologic and clinicopathologic characteristics of patients with known human immunodeficiency virus infection (HIV) admitted to hospital through the emergency department is presented. METHODS: A cohort study of patients with known HIV seropositivity who consecutively attended the emergency department of the Hospital del Mar in Barcelona, Spain, from January to March 1995 and who required hospitalization with follow up until discharge from hospital was performed. From the clinical history of each patient the following parameters were analyzed: age, sex, domicile, toxicologic history, risk factors 'for HIV infection, epidemiologic and pathologic history, CD4 lymphocyte count, clinical stage, the complementary tests carried out, as well as the diagnosis on admission and hospital discharge. RESULTS: During the study period, 6,379 patients were attended in the emergency department, 323 of whom corresponded to HIV seropositive patients. Of 1,460 admissions, 126 (77 males [61%] and 49 females [39%]) corresponded to known HIV patients, of whom 75.5% were or had been intravenous drug addicts. Eighty-three point three percent were from the health care area assigned to the hospital. According to the AIDS clinical stage, 26 (20.6%) belonged to group A, 14 (11.1%) to group B and 86 (68.2%) to group C. The complementary tests performed were: thorax radiography in 80%, abdomen radiography in 4%, cerebral computerized axial tomography (CAT) in 9.5%, lumbar punction in 5%, thoracocentesis in 3%, paracentesis in 4% and clinical analysis in 95%. The most frequent cause of admission was pulmonary disease (40%) with 21.5% corresponding to tuberculosis. Homogenesis among diagnoses on admission and discharge was 75%. CONCLUSIONS: The high percentage of hospitalary admissions in known HIV patients requiring medical attention in the emergency department is of note. The patients are usually from the health care area of the center, belong to group C, require a high number of complementary tests with pulmonary disease being the most frequent cause of admission.

AIDS-Related Opportunistic Infections↗
PubMed1996

Laminin inhibits amyloid-beta-peptide fibrillation.

Laminin, an important extracellular matrix component is induced by brain injury and colocalizes with amyloid-beta-peptide (A beta) deposits in Alzheimer brains. We report here that laminin inhibits amyloid fibril formation as determined by thioflavin T fluorescence spectroscopy and electron microscopic examination. The inhibition of amyloid formation by laminin was concentration dependent and was observed at a laminin concentration of 300 nM, corresponding to a laminin/A beta protein molar ratio of 1:800. The potential effect of laminin, may prove important to inhibit A beta fibrillogenesis in vivo, specifically at the level of cerebral blood vessels.

Amyloid beta-Peptides↗
PubMed1996

[Fibrinolytic treatment in acute myocardial infarction: analysis of delay].

BACKGROUND: The delay time from the onset of symptoms to the initiation of intravenous fibrinolytic treatment in patients with acute myocardial infarction (AMI) is herein described. METHODS: A study was carried out of the consecutive AMI diagnosed in the Medical Area of the Emergency Department of the Hospital del Mar in Barcelona, Spain, with a 24-hour follow up from 15 May 1993 to 14 January, 1994. All the patients under the age of 80 years with transmural AMI of any localization and evolution of under 6 hours were considered to receive fibrinolytic treatment. The following delay times were analyzed: total delay time, extrahospitalary delay time and intrahospitalary delay time, which included assistance delay time, delay in fibrinolytic treatment indication and delay time in performance of the same. RESULTS: During the study period 18,316 patients were attended in the Emergency Medical Area, of which 80 corresponded to AMI. Fibrinolytic treatment was initiated with intravenous streptokinase in 33 patients (41.3%). The total delay time was 287.2 +/- 202.6 (mean +/- SD) minutes; the extrahospitalary and intrahospitalary delays were 159.8 +/- 151.7 and 126.8 +/- 161.7 minutes, respectively. The delay time for assistance was 8.5 +/- 12.7 minutes, the delay time in treatment indication was 78.8 +/- 101.8 minutes and in performance it was 39.5 +/- 52.6 minutes. This latter time was analyzed on the basis of the administration site, with statistically significant differences (p < 0.005) if the fibrinolytic treatment was performed in the Emergency Medical Area (12.5 +/- 0.7 minutes), in the observation room (41.4 +/- 50.7 minutes) or in the Intensive Care Unit (61.4 +/- 75.8 minutes). CONCLUSIONS: Most of the intrahospitalary delay in the administration of fibrinolytic treatment is due to decision delay in regards to carrying out this therapy.

Aged↗
PubMed1996

Interleukin 1 (IL-1)-dependent melanoma hepatic metastasis in vivo; increased endothelial adherence by IL-1-induced mannose receptors and growth factor production in vitro.

BACKGROUND: The growth of cancer cells in inflammatory tissue is often observed. This can be the result of favorable conditions for endothelial cell adherence and/or increased production of local growth factors. PURPOSE: The role of the proinflammatory cytokine interleukin 1 (IL-1) in the prometastatic and growth-promoting environment of inflammation was studied in vivo, and the mechanism of cytokine action was studied in vitro as well. METHODS: Systemic inflammation was induced by the intravenous injection of IL-1 beta or lipopolysaccharide (LPS), and the hepatic metastasizing ability of B16 melanoma (B16) cells following intrasplenic injection was studied. IL-1 receptor blockade was accomplished with the use of the IL-1 receptor antagonist (IL-1Ra). In vitro, IL-1Ra was used to assess the mechanism for prometastasis and growth promotion of cultured hepatic sinusoidal endothelium stimulated with LPS. RESULTS: There was a statistically significant (P < .01) enhancement in the parameters of hepatic metastasis when B16 cells were injected intrasplenically either 4 hours after IL-1 injection or 6 or 12 hours after LPS injection. IL-1Ra pretreatment reduced IL-1-induced enhancement of metastasis by 73%-87% and completely inhibited the augmentation of metastasis following LPS injection. In vitro, the adherence of melanoma cells to LPS-treated endothelium increased nearly twofold but was completely abrogated when IL-1Ra was added before LPS. Similar to melanoma adherence, a 2.5-fold increase (P < .05) in functional mannose receptors was observed with LPS treatment but was prevented by the addition of IL-1Ra did not affect basal mannose-receptor activity in unstimulated epithelium. Mannose-receptor activity and B16 cell adherence significantly correlated (r = .9) with LPS treatment. Conditioned medium from LPS-stimulated epithelium augmented B16 cell proliferation compared with control conditioned medium (P < .01). Production of B16 cell growth factor(s) was markedly reduced (P < .01) when IL-1Ra was added. CONCLUSIONS: These results demonstrate that systemic inflammation induces an enhancement of melanoma cell metastasis and growth by IL-1-dependent mechanisms in vivo. In vitro, the mechanism(s) is consistent with IL-1-mediated increase in expression of mannose receptors and production of tumor cell growth factor(s) from the endothelium. IMPLICATIONS: Given the multiple and complex cytokine cascade induced in vivo and in vitro during LPS-induced systemic inflammation, IL-1 plays a strategic role. Since IL-1Ra is without side effects in humans, studies on intraoperative infusion of IL-1Ra during tumor resection may be indicated.

Animals↗
PubMed1996

Interleukin-1-mediated H2O2 production by hepatic sinusoidal endothelium in response to B16 melanoma cell adhesion.

We have examined H2O2 production by in vitro enriched hepatic sinusoidal endothelium (HSE) during interleukin-1 beta (IL-1 beta) stimulation and B16 melanoma cell adhesion. Production of H2O2 was quantified by flow cytometry and multiwell plate-scanning fluorimetry of intracellular 2', 7'-dichlorofluorescein (DCFH) oxidation in HSE. Under IL-1 beta treatment there was a 6-fold increase in endothelial cells producing H2O2 (67%) and a 4-fold augmentation in the Kupffer cell population (86%). The average H2O2 content per cell size unit significantly (P < 0.01) increased in endothelial cells (2.6-fold) and Kupffer cells (1.7-fold). In contrast to the homogeneity of Kupffer cells, H2O2 production intensity was largely heterogeneous in IL-1 beta-activated HSE. Enhancement of H2O2 production by IL-beta-treated HSE started at the 4th h and peaked 2-3 h later. The addition of increasing concentration of IL-1 beta to HSE for 4 h caused the progressive activation of H2O2 production by treated cells. The addition of 80 M excess of IL-1 receptor antagonist (IL-1 Ra) 10 min before IL-1 beta treatment abrogated IL-1 beta-mediated enhancement of H2O2. From the 2nd h of B16 melanoma adhesion to HSE there was significantly (P < 0.05) enhancement of H2O2 content in HSE. This activation increased 2.25-fold by the 3rd h of coculture and had reduced again by the 5th h. IL-1 Ra (80 ng/ml) given to HSE 10 min before melanoma cells abrogated the HSE response to melanoma cells. The addition of 1% paraformaldehyde (PFA)-fixed B16 melanoma cells to HSE did not affect H2O2 production response, indicating that HSE-activating agents were on the melanoma cell surface. Preincubation of B16 melanoma cells in the presence of 5 micrograms/ml anti-mouse IL-1 beta neutralizing antibody reduced the melanoma cell-induced HSE production of H2O2 by 80%. On the contrary, B16 melanoma cell-conditioned medium did not vary HSE production of H2O2 compared to control HSE. Western blot analysis of cytosolic and membrane sediments from B16 melanoma cells confirmed the presence of IL-1 beta (17.4 kDa) in both cell compartments. Thus, HSE responded to melanoma cell contact with a rapid production of H2O2. HSE activation was IL-1-dependent. This cytokine was directly provided to HSE by the cell surface of adhered melanoma cells.

Animals↗
PubMed1996

HIV-1, HIV-2, HTLV-I/II and STD among female prostitutes in Buenos Aires, Argentina.

To determine the prevalence of HIV-1 and HTLV-I/II among female prostitutes from different areas of the city of Buenos Aires, we studied serum samples from 237 individuals (mean age: 25; range 17 to 39). Prostitutes were recruited from 16 different Buenos Aires locations with different economical status. Information on sexual behaviour, health and socioeconomic conditions was collected through a questionnaire. HIV-1 and HTLV-I/II antibodies (ab) were tested by ELISA (Abbott) and Particle agglutination (Fujirebio, Tokyo) respectively. Positive results were confirmed by immunofluorescence assay. Samples that were positive for HIV-1 antibodies were also tested for p24 antigen (Abbott). VDRL for syphilis was performed in all samples. Fifteen (6.3%) out of the 237 individuals were positive for HIV-1 antibodies. Moreover, 2 (0.8%) HIV-1 seropositive prostitutes were also positive for HTLV-I/II antibodies and for HIV p24-Ag. Even though PCR for HTLV-I/II was not performed, titration by IFA in these two samples suggests HTLV-I. Our serologic results indicate a relatively high HIV-1 infection among prostitutes working in Buenos Aires. As we previously mentioned for other risk groups, we found an association between HTLV-I/II and HIV-1 infection in this particular group. Although we did not find any significant difference between HIV-1 seropositivity and the variables analyzed through the questionnaire, the prevalence of HIV-1 infection was higher in prostitutes working in mask brothels ('sauna or massage houses') as compared with hotel or street prostitutes.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Unusual manifestations of postnatally acquired cytomegalovirus infection: findings on CT and MR.

An infant with unusual CT and MRI manifestations of postnatally acquired cytomegalovirus (CMV) infection is presented. The child exhibited extensive inflammatory lesions in the periventricular area and at the level of the quadrigeminal plate with the formation of a pseudotumour at this level. The latter produced aqueduct obstruction resulting in hydrocephalus. These findings have not previously been described in the literature.

Cerebral Aqueduct↗
PubMed1996

Characterization of ATP-diphosphohydrolase from rat mammary gland.

ATP-diphosphohydrolase (or apyrase) hydrolyses nucleoside di- and triphosphates in the presence of millimolar concentration of divalent cations. It is insensitive towards sulfhydryl and aliphatic hydroxyl-selective reagents and to specific inhibitors of ATPases. We present further evidence that ATPase and ADPase activities present in rat mammary gland correspond to apyrase. Two kinetic approaches have been employed, competition plot and chemical modification with group-selective reagents. The M(r) of these activities was determined by 60Co radiation-inactivation. The kinetic approaches employed, competition plot (which discriminate whether competitive reactions occur at the same site) and chemical modification, point to the presence of a single protein which hydrolyses ATP and ADP. The similar M(r) values of ATPase and ADPase activities also support this proposal. ATPase and ADPase activities of mammary gland show a similar sensitivity or insensitivity towards several chemical modifiers. These results suggest that this enzyme is ATP-diphosphohydrolase, also known as apyrase. The results obtained are compared with the ones obtained by us and other authors with the enzyme isolated from other sources.

Adenosine Triphosphatases↗
PubMed1996

ATP-diphosphohydrolase activity in rat renal microvillar membranes and vascular tissue.

Ecto-nucleotidases may have a role in the regulation of purinoceptor-mediated responses. ATP-diphosphohydrolase or apyrase has been described as an ecto-nucleotidase, which is characterized by a low specificity for its substrates and bivalent cations. The aim of this work was to demonstrate the presence of apyrase as an ecto-enzyme in the rat kidney. ATPase-ADPase activities of the renal microvillar membrane preparation, which correspond to "right side out' membranes, were characterized. The detection of ATP-diphosphohydrolase in the renal vasculature was done through perfusion of isolated rat kidney. ATPase-ADPase activities of the microvillar membrane preparation and apyrase share similar kinetic properties. These include: low substrate and bivalent metal specificities and insensitivity towards inhibitors like: oligomycin, ouabain, verapamil, levamisole and Ap5A. The M(r) or native ATPase and ADPase activities was determined by the 60Co irradiation-inactivation technique being around 65 kDa for both hydrolytic activities. Immunowestern blot analysis also supports the presence of apyrase in microvilli. Perfusion of isolated rat kidney with ATP and ADP, in the presence or absence of different inhibitors or apyrase antibodies indicated the existence of this enzyme in the vascular endothelium. The identification of ATP-diphosphohydrolase as an ecto-enzyme both in microvilli and vasculature support the proposal that the enzyme may have an important role in the extracellular metabolism of nucleotides.

Adenosine Triphosphatases↗
PubMed1996

Acetylcholinesterase accelerates assembly of amyloid-beta-peptides into Alzheimer's fibrils: possible role of the peripheral site of the enzyme.

Acetylcholinesterase (AChE), an important component of cholinergic synapses, colocalizes with amyloid-beta peptide (A beta) deposits of Alzheimer's brain. We report here that bovine brain AChE, as well as the human and mouse recombinant enzyme, accelerates amyloid formation from wild-type A beta and a mutant A beta peptide, which alone produces few amyloid-like fibrils. The action of AChE was independent of the subunit array of the enzyme, was not affected by edrophonium, an active site inhibitor, but it was affected by propidium, a peripheral anionic binding site ligand. Butyrylcholinesterase, an enzyme that lacks the peripheral site, did not affect amyloid formation. Furthermore, AChE is a potent amyloid-promoting factor when compared with other A beta-associated proteins. Thus, in addition to its role in cholinergic synapses, AChE may function by accelerating A beta formation and could play a role during amyloid deposition in Alzheimer's brain.

Acetylcholinesterase↗
PubMed1996

Hepatic sinusoidal endothelium heterogeneity with respect to mannose receptor activity is interleukin-1 dependent.

Using fluorescein isothiocyanate-conjugated ovalbumin (OVA-FITC), 125I-mannan, or 125I-invertase as specific ligands for the mannose receptor, we have quantified its activity in mouse and rat hepatic sinusoidal endothelium (HSE), under both basal conditions and after lipopolysaccharide (LPS) or human recombinant interleukin-1beta (IL-1beta) stimulations. Mouse treatment for 4 hours with 5 microg/kg IL-1beta significantly increased OVA-FITC uptake by HSE. Ligand uptake exhibited a sublobular compartmentalization: In control mice as well as in IL-1beta-stimulated mice, the ligand distributed preferentially in the periportal and septal areas; no OVA-FITC was observed in the perivenous sinusoids. In vitro exposure of mouse HSE to 100 pg/mL LPS or 1 ng/mL IL-1beta for 6 hours significantly (P < .01) increased OVA-FITC uptake. Blocking IL-1 receptors in HSE by addition of 100 ng/mL IL-1 receptor antagonist (IL-1Ra) before stimulation with LPS or IL-1beta abrogated the increase in mannose receptor-mediated uptake. In vitro endocytosis assays showed that rat HSE uptake of 125I-mannan or 125I-invertase progressively increased with both exposure time and concentration of added IL-1beta. Upregulation of mannose receptor-mediated uptake in response to IL-1beta or LPS was also blocked by previous addition of IL-1Ra to rat HSE. Flow cytometric analysis showed a significant HSE heterogeneity in mannose receptor-mediated endocytosis in response to IL-1beta treatment: type I endothelial cells (EC-I, defined by their small size and high cytoplasmic density) significantly (P < .01) increased OVA-FITC uptake compared with type II endothelial cells (EC-II, defined by their large size and low cytoplasmic density). In addition, the subset of EC-I contained three times more IL-1beta-binding cells than the EC-II subset. Because EC-I and EC-II are preferentially located in the periportal and perivenous segments of hepatic sinusoids, respectively, these results suggest that IL-1beta, apart from upregulating mannose receptor activity, contributes to the sublobular compartmentalization of this endothelial cell function.

Animals↗
PubMed1996

Genesis and evolution of high-ploidy tumour cells evaluated by means of the proliferation markers p34(cdc2), cyclin B1, PCNA and 3[H]-thymidine.

Although cell polyploidization is not an infrequent event in mammalian cells and is common in tumours, the mechanisms involved are not well understood. Using the murine B16 cell line as a model, we evaluated the role of some key proteins involved in cell cycle progression: p34(cdc2), cyclin B1 and PCNA. By means of flow cytometry, we showed that both in modal- and in high-ploidy subpopulations, almost all cells were p34(cdc2)-positive. In the modal-ploidy subpopulation only 17.1% cells were cyclin B1-positive and 85.6% PCNA-positive; in contrast, in the high-ploidy subpopulation up to 91.8% cells were cyclin B1-positive and 97.3% cells were PCNA-positive (P < 0.001). Immunofluorescence microscopy showed that PCNA was located in the nucleus; p34(cdc2), both in the nucleus and cytoplasm; and cyclin B1 yielded a cytoplasmic spotted pattern with a perinuclear reinforcement. After a 24-h incubation with 3[H]-thymidine followed by withdrawal of the isotope, high-ploidy cells remained labelled 8 days after thymidine withdrawal, in contrast to modal-ploidy cells. Taken together, our results suggest that polyploid cells are not quiescent, their cell cycle is longer than that of the modal-ploidy population, and they maintain cyclin B1 throughout the cycle, which may contribute to their genesis by impeding the exit from mitosis.

Animals↗
PubMed1996

[Risk factors for the consumption of illegal drugs. Study in 1904 18-year-old boys in the city of Buenos Aires].

During September 1988 an anonymous, self-administered survey was carried out among a random sample of 18-year-old boys living in Buenos Aires city. The characteristics of 232 boys who reported illegal drug usage during the previous year were compared against those of the 1672 who denied drug consumption during that period. Forward stepwise multiple logistic regression analysis showed strong association between drug use and drug consumption by friends (OR 18.6) or brother/sister (OR 4.3), and consumption of tobacco or alcohol (OR 4.5 and 4.2 respectively). Results show different characteristics that can facilitate the primary care physicians' task of prevention and diagnosis of drug consumption in his/her patients.

Adolescent↗