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Biomedical subjects

A Alonso

Publications and source records attributed to A Alonso.

At least 289 records · Page 16Linked to original sources
PubMed1995

Papillomavirus capsid binding and uptake by cells from different tissues and species.

The inability of papillomaviruses (PV) to replicate in tissue culture cells has hampered the study of the PV life cycle. We investigated virus-cell interactions by the following two methods: (i) using purified bovine PV virions or human PV type 11 (HPV type 11) virus-like particles (VLP) to test the binding to eukaryotic cells and (ii) using different VLP-reporter plasmid complexes of HPV6b, HPV11 L1 or HPV11 L1/L2, and HPV16 L1 or HPV16 L1/L2 to study uptake of particles into different cell lines. Our studies showed that PV capsids bind to a broad range of cells in culture in a dose-dependent manner. Binding of PV capsids to cells can be blocked by pretreating the cells with the protease trypsin. Penetration of PV into cells was monitored by using complexes in which the purified PV capsids were physically linked to DNA containing the gene for beta-galactosidase driven by the human cytomegalovirus promoter. Expression of beta-galactosidase occurred in < 1% of the cells, and the efficiency of PV receptor-mediated gene delivery was greatly enhanced (up to 10 to 20% positive cells) by the use of a replication-defective adenovirus which promotes endosomal lysis. The data generated by this approach further confirmed the results obtained from the binding assays, showing that PV enter a wide range of cells and that these cells have all functions required for the uptake of PV. Binding and uptake of PV particles can be blocked by PV-specific antisera, and different PV particles compete for particle uptake. Our results suggest that the PV receptor is a conserved cell surface molecule(s) used by different PV and that the tropism of infection by different PV is controlled by events downstream of the initial binding and uptake.

Animals↗
PubMed1995

Human papillomavirus type 16 E5 protein affects cell-cell communication in an epithelial cell line.

The human papillomavirus type 16 (HPV16) E5 protein is considered to have weak oncogenic properties, and its function in infected human keratinocytes is unknown. HPV16 E5 protein has been found to localize to the Golgi apparatus and the plasma membrane. To analyze the effect of E5 on plasma membrane properties, cells from the human keratinocyte cell line HaCaT were transfected with the HPV16 E5 open reading frame under the control of an inducible promoter. The gap junction-mediated cell-cell communication of E5- and vector-transfected cells was analyzed by microinjection of Lucifer yellow to measure dye coupling of the cells. A strong impairment of dye transfer in E5-transfected cells but not in vector-transfected cells was observed, with more than 80% dye transfer inhibition 40 min after injection. This impairment correlated with dephosphorylation of connexin 43, the major gap junctional protein in HaCaT cells. Furthermore, the dye coupling inhibition was not the result of differentiation of the E5-expressing cells, since no overexpression of cytokeratin 1 or filaggrin, markers of HaCaT cell differentiation, could be observed. These results therefore strongly suggest a correlation between expression of the HPV16 E5 open reading frame, impairment of gap junction-mediated dye coupling, and dephosphorylation of connexin 43.

Cell Communication↗
PubMed1995

Association between HLA class II antigens and primary antiphospholipid syndrome from the south of Spain.

Recent studies have suggested an association between primary antiphospholipid syndrome (PAPS), antiphospholipid antibodies and some major histocompatibility complex (MHC) antigens. We have studied the relationship between MHC class II antigens and PAPS in 19 patients from the south of Spain. Univariant analysis showed an association between PAPS and HLA-DQ7 (47% vs 25%l P = 0.3), DR4 (32% vs 16%; P = 0.08) and DQ3 (63% vs 39%; P = 0.04). However, multivariant analysis confirmed the association with DQ7 (RR = 2.5; CI 80%: 1.3-4.7) and DR4 (RR = 2.2; CI 80%: 1.1-4.4) but not with DQ3. When we introduced DRw53 into this analysis, we noticed a DR4 confounding effect, with DQ7 (RR = 3.1; CI 80%: 1.7-5.8) and Drw53 (RR = 2.3; CI 80%: 1.2-4.4) remaining as the most important HLA antigens related to PAPS. In conclusion, in PAPS patients from the South of Spain, HLA-DQ7 antigen showed the highest relative risk for PAPS, followed by DRw53.

Abortion, Spontaneous↗
PubMed1995

Stratum corneum intercellular lipid as compared to erythrocyte ghosts: an ESR study of thermotropic behavior and nitroxide reduction. Electron Spin Resonance.

Intercellular membranes of Stratum Corneum and erythrocyte ghosts were studied through partition of Tempo nitroxide spin label. Stratum Corneum presents a phase transition-monitored by the spin label at 58 degrees C--that is in agreement with data obtained through the use of other techniques. A reduction of the nitroxide is observed. Erythrocyte ghosts at protein concentrations higher than the values generally used in ESR studies (above 15 mg/ml) also show the partition and reduction of Tempo. Experimental data suggest that the reduction mechanism might be common to both types of membranes involving probably the membrane lipoperoxidation as well as protein oxidation.

Animals↗
PubMed1995

[Polypoid cystitis mimicking bladder tumor].

Presentation of one case of polypoid cystitis in a 38 year-old male, with no urological history. The form of clinic presentation and the endoscopic exploration induced to suspect the existence of a bladder tumour. Diagnosis was confirmed by the result of the histopathological study of the piece.

Adult↗
PubMed1995

Somatodendritic internalization and perinuclear targeting of neurotensin in the mammalian brain.

Polypeptide hormones and growth factors have long been known to internalize into peripheral target cells as a result of their interaction with cell surface receptors. Studies in culture have suggested that certain neuropeptides might undergo a similar type of translocation in neurons. To investigate this possibility in adult mammalian brain, we have examined by confocal laser microscopy the events that follow the binding of fluorescein-tagged derivatives of the tridecapeptide neurotensin to basal forebrain cholinergic cells. Our results demonstrate a selective time- and temperature-dependent internalization of fluo-neurotensin in these cells. This internalization is receptor mediated, proceeds from the entire somatodendritic membrane of the cells, and utilizes endosome-like organelles which are mobilized from dendrites to perikarya and from the periphery of the cell to its perinuclear region. Parallel studies carried out on Sf9 insect cells expressing the rat neurotensin receptor from a recombinant baculovirus indicated that the internalization process involves receptor-ligand complexes and not merely the fluorescent peptide itself. These data suggest that receptor internalization plays a role in neuropeptide signaling in the brain and that it can be harnessed for selective identification of neuropeptide target cells.

Animals↗
PubMed1995

[Antiphospholipid antibodies in women with habitual abortions. Treatment with prednisone and acetylsalicylic acid during pregnancy].

PURPOSE: To discover the prevalence of antiphospholipid antibodies in women with a history of repeated miscarriages. Therapy evaluation of aspirin and prednisone to achieve living term foetus from women in whom antiphospholipid antibodies had been detected and who had become pregnant again. PATIENTS AND METHODS: 82 consecutive women with history of at least of two miscarriages, with no live foetus in either case. 14 women positive for antiphospholipid antibodies who had become pregnant again (group of therapy evaluation), were treated with aspirin (125 mg/d) and prednisone (20 mg/d). 60 normal pregnant women (control group). Lupus anticoagulant evaluation: APTT tests caolin clotting time and APTT system neutralized with platelet phospholipids. Antiphospholipid antibodies: ELISA test. RESULTS: 13.4% were positive to antiphospholipid antibodies (ELISA), and 2.4% were positive in both positive in both test. Therapy evaluation: 75.5% (11 cases) of pregnancies were successful (normal foetus), 14% (2 cases) of fetal losses, and 7% (1 case) of foetal malformations (acranius). CONCLUSIONS: In our study the antiphospholipid antibodies represent one of the main causes of repeated foetal losses. We recommended in cases of infertile women to test for antiphospholipid antibodies regularly. We confirm the effectiveness of the therapy (aspirin and prednisone) in achieving successful pregnancies in patients with a history of infertility.

Abortion, Habitual↗
PubMed1995

ENDO A cytokeratin expression in the inner cell mass of parthenogenetic mouse embryos.

During the preimplantation period of development, the first cellular polarization and diversification of the mouse embryo occurs. This process starts at the eight-cell stage and is directly driven by the cytoskeleton. Cell polarization finally leads to the first embryonic epithelium, the trophectoderm, characterized by the presence of cytokeratins. It has not been described whether genomic imprinting, an epigenetic modification of certain genes depending on the parent-of-origin, affects preimplantation development. However, implantation is one of the steps in which an exceptionally high mortality rate is observed in mouse parthenogenetic embryos, a phenomenon that may be influenced by a deficiency in trophectoderm differentiation. To assess this possibility we analyzed the expression of various cytoskeletal proteins in late preimplanted embryos. No differences were observed in the expression of microtubules and microfilaments, but surprisingly, the undifferentiated cells of the parthenogenetic inner cell mass showed distinct cytokeratin staining. This anomalous cytoskeleton expression may be considered as one of the earliest manifestation described to date of the effect of genomic imprinting in development.

Animals↗
PubMed1994

The promoter of the H1zero histone gene contains a DNA element bound by retinoic acid receptors.

Retinoic-acid mediated differentiation of F9 cells is accompanied by an increased transcription of the histone H1zero gene. This increase is an early response after addition of retinoic acid, suggesting a direct effect of the hormone on transcription of the gene. We show now that the promoter of histone H1zero contains a DNA element, localized 531 base-pairs upstream of the cap site, that is composed of a direct repeat of the sequence PuGGTCA separated by eight base-pairs. This element confers retinoic acid responsiveness to a heterologous thymidine kinase promoter in F9 and HeLa cells. Furthermore, the element forms retarded complexes not only with bacterially expressed retinoic acid receptors (RARs) and retinoid X receptors (RXRs), but also with endogenous F9 receptors. Our results suggest therefore that retinoic acid receptors can control the expression of a chromatin structural gene the expression of which is associated with a differentiated phenotype.

Animals↗
PubMed1994

An assessment of the biochemical applications of the non-ionic surfactant Hecameg.

A number of properties and effects of the novel non-ionic detergent Hecameg (6-O-(N-heptylcarbamoyl)-methyl-alpha-D-glucopyranoside) have been examined in view of its possible biochemical applications. In particular, its critical micellar concentration has been measured, and its effects on pure lipid membranes, soluble and membrane-bound enzymes have been recorded. Hecameg has some advantageous and some less advantageous properties; its relatively high critical micellar concentration (16.5 mM), almost insensitive to pH or ionic strength changes, makes it suitable for reconstitution procedures in which detergent must be removed by dialysis. It is also an effective lipid-solubilizing agent, producing leakage of vesicle contents at detergent concentrations well below the solubilizing range. Among the drawbacks, the presence of an amide group in the molecule may interfere with the protein amide group in spectroscopic measurements. It also appears to be less gentle than other nonionic surfactants towards certain enzyme activities.

Adenosine Triphosphatases↗
PubMed1994

[Response of arterial pressure to mental stress in young patients with high or mild arterial hypertension. Does it reflect the changes in arterial pressure observed during its ambulatory monitoring?].

BACKGROUND: The use of cardiovascular reactivity tests in the laboratory is based on their probable capacity to predict blood pressure response in stress situations of everyday life. These responses may be estimated from the values obtained by out patient monitorization or blood pressure (OPMBP). METHODS: OPMBP was carried out over 24 hours by Spacelabs 90202 monitor in 57 subjects from 18-40 years of age with high or slightly high blood pressure (mean blood pressure diagnosed 143 +/- 12/91 +/- 8 mmHg) with a Quetelet index of 25.8 +/- 9 kg/m2. Two mental stress tests were applied: the mental arithmetic test (MAT) and a structured interview (SI) in 38 patients with high or slightly high blood pressure (HBP) and to 18 healthy normotense subjects of the same age group. RESULTS: The increases in systolic BP (SBP) and diastolic BP (DBP) observed during MAT and SI were similar: r = 0.88 and r = 0.68, respectively (p < 0.0001, both). The percentage of hyperreactive subjects, defined as those presenting an absolute increase in SBP > or = 25 mmHg and/or an increase of DBP > or = 15 mmHg was greater between those with slightly high blood pressure (70%) and high blood pressure (43%) in both tests than among the normotense subjects of the control groups (28%) (p < 0.05). Upon study of the relation between response to BP during the mental stress tests and the values of BP obtained with OPBPM, a positive correlation was found between the increase in DBP in MAT and the SI and mean 24 hour DBP (r = 0.39 and r = 0.45, p < 0.025 and p < 0.01, respectively). CONCLUSIONS: The correlation of the absolute increase in systolic and diastolic blood pressure during two different mental stress tests in young subjects with high or slightly high blood pressure is very high. The correlation between the increase in blood pressure to mental stress in the laboratory and the blood pressure values obtained during non invasive out patient monitorization was found to be only intermediate for diastolic blood pressure nad null for systolic blood pressure in this study.

Adolescent↗
PubMed1994

Real-time measurements of chemically-induced membrane fusion in cell monolayers, using a resonance energy transfer method.

Fusion of mouse melanoma cells grown in monolayers has been directly monitored by fluorescence resonance energy transfer between fluorescein and rhodamine probes attached to octadecanoic acid. Various poly(ethylene glycol)s (PEG), either alone or in combination with amphipathic molecules, have been used as fusogens. Fusion starts at a maximum rate as soon as PEG is removed from the medium and reaches a plateau after 20-30 min. Both the initial rate and extent of fusion have been recorded for each experiment. The extent of fusion shows in general a positive correlation with the initial rate, although PEGs with different molar masses appear to induce fusion at different rates, but to a similar extent. A good correlation has been found between the extent of fusion, as measured by fluorescence, and the 'fusion index' computed from cell and nucleus counting; a calibration curve is provided for the interconversion of both parameters. Optimum fusion values are obtained with 50% (w/v) PEG 1500. The effect of pre-treatments with surfactants (Triton X-100, sodium dodecylsulphate) on PEG-induced fusion has also been tested. Sodium dodecylsulphate, but not Triton, enhances considerably both the rate and extent of cell fusion. The in situ generation of the amphipathic molecule diacylglycerol, through the catalytic activity of a phospholipase C, also enhances significantly the fusion parameters. These results are in good agreement with previous studies based on syncytia counting.

Animals↗
PubMed1994

Intrapleural fibrinolytic treatment of multiloculated thoracic empyemas.

Acute multiloculated thoracic empyemas incompletely drained by tube thoracostomy alone usually require operation. To avoid a thoracotomy yet treat this difficult problem, intrapleural fibrinolytic agents were employed. Between April 1, 1990, and April 1, 1993, 13 consecutive patients presenting with a fibrinopurulent empyema were demonstrated to have incomplete drainage. To facilitate drainage, streptokinase, 250,000 units in 100 mL 0.9% saline solution (3 patients), or urokinase, 100,000 units in 100 mL 0.9% saline solution (10 patients), was instilled daily into the chest tube, and the tube was clamped for 6 to 12 hours followed by suction. This routine was continued daily for a mean of 6.8 +/- 3.7 days (range, 1 to 14 days) until resolution of the pleural fluid collection was demonstrated by computed chest tomography and clinical indications. This regimen was completely successful in 10 of 13 patients (77%), who had resolution of the empyema, eventual withdrawal of chest tubes, and no recurrence. Two patients, both pediatric liver transplant patients, had an initial good response but eventually required decortication. One patient with a good radiographic response became increasingly febrile during streptokinase therapy and underwent a thoracotomy, but no significant undrained fluid was found. This patient's continued fever was believed to be a streptokinase reaction. Urokinase was used subsequently. No treatment-related mortalities or complications occurred. Intrapleural fibrinolytic agents, especially urokinase, are safe, cost-effective means of facilitating complete chest tube drainage, thereby avoiding the morbidity of a major thoracotomy for 77% of a group of multiloculated empyema patients who traditionally would have required open surgical therapy.

Adult↗
PubMed1994

Application of monoclonal antibodies to quality control of foot-and-mouth disease vaccines.

Panels of monoclonal antibodies (mAbs) produced against foot-and-mouth disease (FMD) virus types O, A and C were selected for cell culture neutralization titre (NT), mouse protection index (MPI), trypsin sensitivity (TS) and avidity to different epitopes. The selected sets were used to assay the antigen concentration and the fit between FMDV vaccine and challenge strains. It was observed that FMD vaccines protect more than 75% of vaccinated cattle when manufactured with antigens characterized by (1) a high degree of fit with the potency control virus, and (2) mean ELISA 50% titres (T50) > 28 for O, > 18 for A and > 75 for C types, respectively, using the corresponding mAb set.

Animals↗
PubMed1994

Tuberculosis in the Republic of Cuba: its possible elimination.

SETTING: Tuberculosis elimination is a priority in most developed countries, although the AIDS epidemic and drug resistance are a handicap in some of them. Tuberculosis is an even greater problem in developing countries. OBJECTIVE: To evaluate the epidemiological situation in Cuba, the trend of new cases reported for 1979-91 by clinical category and age group is described. DESIGN: A simple regression model was fitted to the time series data on 'new case' rates taken from the national surveillance system. The annual variation percentage was estimated. RESULTS: From 1979-91 tuberculosis decreased by 59.5% (from 11.6-4.7 per 10(5) persons per year). This decline occurred in all age groups; 60% of new cases in 1991 were aged 45 years and over, of which 30% were aged 65 and over. Drug resistance of Mycobacterium tuberculosis strains (2.49% in 1989) remains uncommon and HIV infection (0.009% in 1991) is rare in the general population. CONCLUSIONS: The continuing steady decline of the number of new cases reported, in addition to the favorable trend of drug resistance and the low rate of HIV infection in the general population so far seem to indicate the real possibility of maintaining the effectiveness of the National Programme for Tuberculosis Control in the future, making it reasonable to formulate new strategies for the elimination of the disease.

Adolescent↗
PubMed1994

Phagocytic cell function in active brucellosis.

In this study, we analyzed phagocytic cell function in 51 patients with active brucellosis and its relationship with different clinical, serological, and evolutionary variables. A control group was made up of 30 blood donors of similar geographic extraction, age, and sex, with no previous history of brucellosis or known exposure ot the infection or specific antibodies. The investigations were carried out at the time of diagnosis, at the conclusion of treatment, and after 6 months of follow-up. Polymorphonuclear leukocyte adherence and nitroblue tetrazolium reduction in response to Brucella antigen were significantly increased in the patients at the time of diagnosis with respect to the control group. In contrast, chemotaxis in response to Brucella antigen and phagocytosis were significantly reduced in the patients with respect to the control group. The alterations in phagocytic cell function were greater in patients with bacteremia, with focal forms of the disease, or with a longer diagnostic delay. Most of these initial alterations tended to normalize with treatment, indicating their transient character.

Adolescent↗
PubMed1994

Effects of human chromosome 12 on interactions between Tat and TAR of human immunodeficiency virus type 1.

Rates of transcriptions of the human immunodeficiency virus are greatly increased by the viral trans activator Tat. In vitro, Tat binds to the 5' bulge of the trans-activation response (TAR) RNA stem-loop, which is present in all viral transcripts. In human cells, the central loop in TAR and its cellular RNA-binding proteins are also critical for the function of Tat. Previously, we demonstrated that in rodent cells (CHO cells), but not in those which contain the human chromosome 12 (CHO12 cells), Tat-TAR interactions are compromised. In this study, we examined the roles of the bulge and loop in TAR in Tat trans activation in these cells. Whereas low levels of trans activation depended solely on interactions between Tat and the bulge in CHO cells, high levels of trans activation depended also on interactions between Tat and the loop in CHO12 cells. Since the TAR loop binding proteins in these two cell lines were identical and different from their human counterpart, the human chromosome 12 does not encode TAR loop binding proteins. In vivo binding competition studies with TAR decoys confirmed that the binding of Tat to TAR is more efficient in CHO12 cells. Thus, the protein(s) encoded on human chromosome 12 helps to tether Tat to TAR via its loop, which results in high levels of trans activation.

Animals↗