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Biomedical subjects

A Cano

Publications and source records attributed to A Cano.

At least 109 records · Page 6Linked to original sources
PubMed1996

Association of autoantibodies against platelet glycoproteins Ib/IX and IIb/IIIa, and platelet-reactive anti-HIV antibodies in thrombocytopenic narcotic addicts.

The levels of platelet-associated Igs (PAIgs) and plasma circulating antiplatelet antibodies were evaluated by a flow cytometric immunofluorescence assay (FCIFA), an enzyme-linked immunoassay (ELISA), and a platelet radioactive antiglobulin test (PRAT), in a group of 45 human immunodeficiency virus (HIV)-infected intravenous drug users (IVDUs), with or without thrombocytopenia (TCP). Direct tests demonstrated an increased amount of PAIgs in 40% of the patients, irrespective of their platelet count. These PAIgs were mainly of IgG class and could not be eluted with ether. Plasma IgG with antiplatelet activity was found in 70% of the thrombocytopenic individuals, whereas it was detected in only one patient without TCP. The relative frequencies of antibodies against the platelet glycoproteins (GPs) Ib/IX and IIb/IIIa were assessed in plasma from all patients by means of the monoclonal antibody-specific immobilization of platelet antigens assay (MAIPA). Plasmas from all non-thrombocytopenic patients were negative when tested by indirect MAIPA. In contrast, 10/23 plasma from thrombocytopenic patients reacted with either GP IIb/IIIa, GP Ib/IX, or both GPs. Finally, aiming to investigate whether HIV antibodies from these patients are reactive with normal platelets, we performed absorption-elution experiments, followed by evaluation of HIV antibodies in the indirect eluates by ELISA and Western blot. Interestingly, we detected anti-HIV antibodies that bind to normal platelet antigens in 50% of the ether eluates prepared from control platelets sensitized with plasma from patients with TCP, but in only 5% of eluates obtained from platelets sensitized with plasma from non-thrombocytopenic patients. The present study provides direct evidence that specific autoantibodies against platelet membrane GPs Ib/IX and IIb/IIIa are common in HIV positive thrombocytopenic individuals. The finding in these patients of HIV antibodies cross-reactive with normal platelets, suggests that mimicry of human antigens by HIV could play a key role in the pathophysiology of the HIV-related TCP.

Adult↗
PubMed1996

The oxidizing agent tertiary butyl hydroperoxide induces disturbances in spindle organization, c-meiosis, and aneuploidy in mouse oocytes.

It has been recently proposed that a concomitant generation of oxidative stress of oocytes with increasing maternal age may be a major factor responsible for the age-related increase in aneuploid conceptions. As a preliminary step in the testing of this hypothesis, we need to confirm that oxidative stress in itself can induce errors in chromosome segregation. In order to achieve this goal, germinal vesicle (GV)-stage mouse oocytes from unstimulated ICR and (C57BL x CBA) F1 hybrid female mice were matured in vitro for 9 h for metaphase I (MI) oocytes or 16 h for metaphase II (MII) oocytes in the presence of varying concentrations of the oxidizing agent tertiary-butyl hydroperoxide (tBH). MII oocytes from (C57BL x CBA) F1 hybrid mice were fixed and C-banded for karyotyping analysis. MI and MII oocytes from ICR mice were fixed and stained with the DNA-fluorescent probe 4',6-diamidino-2-phenylindole (DAPI) to detect abnormalities in chromosomal distribution. Meiosis I and meiosis II spindles from ICR mice were visualized by confocal immunofluorescence microscopy. Data from these experiments demonstrate that in-vitro exposure of mouse oocytes to tBH during meiosis I reduces the length (pole-to-pole distance) and width (diameter at the equator of the spindle) of meiosis I and meiosis II spindles. This reduction is associated with an increase in the percentage of oocytes showing chromosome scattering and clumping on the MII plate, and of aneuploidy (hyperhaploidy) in MII oocytes. However, tBH at the concentrations used in the present study has only a minimal negative effect on the frequency of meiotic maturation. These results suggest that oxidative stress during meiotic maturation in vitro may induce chromosomal errors that are undetectable in the living oocyte and whose developmental consequences may become manifest after fertilization.

Aneuploidy↗
PubMed1996

Role of tyrosine kinase pathways in ETB receptor activation of NHE3.

Endothelin-1 (ET-1) binding to ETB receptors increases the activity of the apical membrane Na+/H+ antiporter (NHE3) of renal proximal tubule and cultured OKP cells. In OKPETB6 cells, a clonal cell line of OKP cells that overexpresses ETB receptors, ET-1-induced increases in Na+/H+ antiporter activity are mediated 50% by Ca2(+)-dependent pathways and 50% by tyrosine kinase pathways. ET-1 induces tyrosine phosphorylation of proteins of 68, 110, 125, 130, and 210 kDa. ET-1-induced tyrosine phosphorylation is mediated by the ETB receptor and is not dependent on increases in cell Ca2+ or protein kinase C. The 68-, 110-, 125-, and 130-kDa phosphoproteins are cytosolic, whereas the 210-kDa phosphoprotein is an integral membrane protein. Immunoprecipitation studies showed that the 68-kDa protein is paxillin and the 125-kDa protein is p125FAK (focal adhesion kinase). Cytochalasin D, which disrupts focal adhesions, prevented ET-1-induced tyrosine phosphorylation of paxillin, p110, p125FAK, and p130 but did not prevent tyrosine phosphorylation of p210 and did not prevent ET-1-induced increases in Na+/H+ antiporter activity. Thus 50% of ETB receptor-induced Na+/H+ antiporter activation is mediated by tyrosine kinase pathways, possibly involving p210. ETB receptor activation also induces tyrosine phosphorylation of focal adhesion proteins, but this is not required for antiporter activation.

Animals↗
PubMed1996

Characterization of the rat NHE3 promoter.

NHE3, a transmembrane protein involved in transcellular ion transport, is expressed in the apical membrane of renal and gastrointestinal epithelia. Chronic regulation by multiple stimuli, including glucocorticoid-induced transcriptional regulation, has been demonstrated. To study the tissue-specific expression and transcriptional regulation of NHE3, the 5' flanking region of the rat NHE3 gene was cloned. Two genomic libraries were screened with the 5' end of the NHE3 cDNA. The 5' flanking region and first exon were isolated. Primer extension mapped a single transcription start site in stomach, colon and kidney. The NHE3 promoter near the transcription initiation site is characterized by the absence of TATA and CAAT sequences. Two Sp1 sites, one Egr-1 site, and an initiator with the sequence GGGATTAAA mark the area of transcription initiation. Upstream sequences include multiple DNA sequence elements recognized by the glucocorticoid and thyroid receptors, Sp1, atriopeptin-2, and several other transcription factors. Transcriptional regulation by glucocorticoids and chronic acidosis was demonstrated. Promoter activity was present in OKP cells, a renal proximal tubule cell line, but not in fibroblasts. This suggests that the NHE3 promoter contains elements conferring epithelial cell-specific expression.

3T3 Cells↗
PubMed1996

Analysis of compliance with oral contraception in Spain.

OBJECTIVE: The study was designed to analyze factors related to compliance in oral hormonal contraception in Spain. METHOD: A review study and a multicenter analysis of experience of compliance by 300 doctors, by means of a questionnaire and discussion about the determinants of contraceptive use. RESULTS: Compliance is a major problem in Spain, being influenced mainly by side-effects, the general perception of the method and personal factors. The different factors involved in non-compliance in Spain were analyzed, with regard to the perspective of the professionals. CONCLUSIONS: Strategies to improve compliance in Spain aim mainly at improving the general perception of the method and the accessibility of family planning centers. Factors associated with compliance are still not well known in our country. Better knowledge of the determinants of non-compliance in Spain is needed. For this purpose, another research group was formed to conduct a national study among women.

Contraception Behavior↗
PubMed1996

[Rhodococcus equi pneumonia in patients with HIV infection: report of 2 cases and review of the literature].

BACKGROUND: Pneumonia by Rhodococcus equi is infrequent and is associated with patients with important immunosuppression. To date 66 cases of pneumonia by Rhodococcus equi in patients with HIV infection have been published. The diagnosis, problems in determining diagnosis and treatment are discussed. MATERIALS AND METHODS: Two new cases of pneumonia by Rhodococus equi in C3 stage patients with HIV infection are reported. Diagnosis was achieved by study of bronchoalveolar lavage samples with the Apy-Coryne method and gas chromatography. RESULTS: The two patients presented pneumonia, one of which was necrotizing pneumonia with localization in the upper left lung and in the lower right lung, respectively. The clinical manifestations were characterized by respiratory involvement of a subacute course with pleural involvement in both cases and hemoptisis in one. Prolonged, combined antibiotic treatment was administered with good response in both cases. One patient died at one year of diagnosis from consumptive syndrome while the other remains asymptomatic. CONCLUSIONS: Infection by Rhodococcus equi should be suspected in HIV patients with slow evolution pneumonia, especially in the pneumonia is necrotizing. Combined i.v. antibiotic treatment is recommended and followed from 3 to 5 months with an association including clarithromycin.

Actinomycetales Infections↗
PubMed1995

Dam methylase from Escherichia coli: kinetic studies using modified DNA oligomers: hemimethylated substrates.

We have measured steady-state kinetics of the N6-adenine methyltransferase Dam Mtase using as substrates non-selfcomplementary tetradecamer duplexs (d[GCCGGATCTAGACG]-d[CGTCTAGATCC-GGC]) containing the hemimethylated GATC target sequence in one or the other strand and modifications in the GATC target sequence of the complementary strands. Modifications included substitution of guanine by hypoxanthine (I), thymine by uracil (U) or 5-ethyl-uracil (E) and adenine by 2,6-diamino-purine (D). Thermodynamic parameters were obtained from the concentration dependence of the melting temperature (Tm) of the duplexes. Large differences in DNA methylation of duplexes containing single dI for dG substitution of the Dam recognition site were observed compared with the canonical substrate, if the substitution involved the top strand (on the G.C rich side). Substitution in either strand by uracil (dU) or 5-ethyluracil (dE) resulted in small perturbation of the methylation patterns. When 2,6-diamino-purine (dD) replaced the adenine to be methylated, small, but significant methylation was observed. The kinetic parameters of the methylation reaction were compared with the thermodynamic free energies and significant correlation was observed.

2-Aminopurine↗
PubMed1995

Overexpression of csk inhibits acid-induced activation of NHE-3.

Opossum kidney OKP cells express an apical membrane Na+/H+ antiporter that is encoded by NHE-3 (for Na+/H+ exchanger 3) and is similar in many respects to the renal proximal tubule apical membrane Na+/H+ antiporter. Chronic incubation of OKP cells in acid medium for 24 hr increases Na+/H(+)-antiporter activity and NHE-3 mRNA abundance. The increase in Na+/H(+)-antiporter activity was not prevented by H7, a protein kinase C/protein kinase A inhibitor, but was prevented by herbimycin A, a tyrosine kinase inhibitor. Incubation of cells in acid medium increased c-src activity, and this was inhibited by herbimycin A. To determine the role of the src family of nonreceptor protein-tyrosine kinases, Csk (for carboxyl-terminal src kinase), a physiologic inhibitor of these kinases, was overexpressed in OKP cells. In three clones overexpressing csk, acid-induced increases in Na+/H(+)-antiporter activity and NHE-3 mRNA abundance were inhibited. In these clones, inhibition of acid activation of Na+/H(+)-antiporter activity paralleled inhibition of acid activation of c-src. Neither herbimycin A nor overexpression of csk inhibited dexamethasone-induced increases in Na+/H(+)-antiporter activity. These studies show that decreases in pH activate c-src and that the src family nonreceptor protein-tyrosine kinases play a key role in acid activation of NHE-3.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Expression of beta 1 integrin receptors in transformed mouse epidermal keratinocytes: upregulation of alpha 5 beta 1 in spindle carcinoma cells.

The adhesive properties and the expression of extracellular matrix receptors of the beta 1-integrin subfamily were analyzed in transformed epidermal keratinocyte cell lines of different stages of mouse skin carcinogenesis. One- and two-dimensional analyses of the immunoprecipitates obtained with anti-beta 1- and specific anti-alpha-integrin subunits showed qualitative and quantitative changes in the expression of beta 1 integrins by the different cell lines. The polyvalent alpha 3 beta 1 integrin was expressed by all analyzed cell lines, although the levels detected in undifferentiated spindle CarC cells were lower than those present in the rest of keratinocyte cell lines. In contrast, spindle cells expressed high levels of the specific fibronectin receptor alpha 5 beta 1, whereas this integrin was absent or expressed at very reduced levels in the other epithelial cell lines. Expression of alpha 5 beta 1 integrin in spindle cells appeared organized in cell-substratum contact areas on spread cells. In addition, high and homogenous expression of alpha 5 beta 1 was detected in fully undifferentiated tumors induced in nude mice by three independent spindle cell lines. These results suggest that the expression of alpha 5 beta 1 integrin is upregulated during the development of spindle cell carcinomas that occur in the last stages of mouse skin carcinogenesis and can be associated with the acquisition of the fibroblastoid phenotype of spindle cells. On the other hand, expression of the collagen receptor alpha 2 beta 1 was demonstrated in a transformed cell line (PDV), and it was apparently also expressed in two other malignant keratinocyte cell lines (PDVC57 and HaCa4). The expression of alpha 2 beta 1 was correlated with the increased adhesion to collagen type I and collagen type IV exhibited by the tumorigenic cell lines.

Animals↗
PubMed1995

Relationship between ERBB2 and E-cadherin expression in human breast cancer.

A recent in vitro study has suggested that overexpression of ERBB2 may mediate breast tumour progression and metastasis by inhibiting the transcription of the E-cadherin (E-CD) gene. To test this hypothesis in human breast cancer in vivo, we studied the relationship between the expression of both molecules in 247 breast carcinomas immunohistochemically. Five ductal carcinomas in situ overexpressed ERBB2 and showed preserved E-CD expression. Forty-four of 226 infiltrating ductal carcinomas (19.47%) showed ERBB2 overexpression, and a statistically significant relationship was found between ERBB2 overexpression and high histological grade. E-CD expression was preserved in 111 cases (49.1%) and correlated with the histological grade. However, no significant relationship was found between ERBB2 and E-CD expression. None of the 16 infiltrating lobular carcinomas expressed ERBB2 or E-CD. These observations in different histological types of breast carcinoma strongly argue against a role for ERBB2 as a transcriptional regulator of E-CD expression in most human breast carcinomas in vivo.

Breast Neoplasms↗
PubMed1995

The effect of estrogen replacement therapy with or without progestogen on the fibrinolytic system and coagulation inhibitors in postmenopausal status.

OBJECTIVE: The aim of this study was to analyze several fibrinolytic components and coagulation inhibitors in postmenopausal women and had to evaluate the effect of hormone replacement therapy. STUDY DESIGN: Several hemostatic parameters were evaluated in 75 postmenopausal women before and after 3 to 4 and 12 months of hormone therapy. RESULTS: An increase in plasma fibrinolytic activity primarily related to a significant increase in tissue-type plasminogen activator and a decrease in plasminogen activator inhibitor type 1 was observed in women receiving hormone replacement therapy. A significant decrease in protein S and lipoprotein(a) was detected under therapy. No modifications in tissue-type plasminogen activator/plasminogen activator inhibitor-1 and activated protein C/alpha 1-antitrypsin complexes, urokinase activity, plasminogen, and antithrombin III were detected. CONCLUSIONS: The increase in fibrinolytic activity and the decrease in lipoprotein(a) levels observed in women receiving hormone replacement therapy could help decrease the risk of coronary disease associated with the postmenopausal state.

Administration, Cutaneous↗
PubMed1995

Differential patterns of placental and epithelial cadherin expression in basal cell carcinoma and in the epidermis overlying tumours.

P-cadherin (P-CD) and E-cadherin (E-CD) are expressed by keratinocytes and play an important role in skin morphogenesis. P-CD expression is restricted to the basal layer of normal epidermis, whereas E-CD is expressed in all the living layers. We have previously reported a reduced expression of E-CD in most cases of infiltrative basal cell carcinoma (BCC). In the present work we have investigated by immunohistochemistry the expression of both P-CD and E-CD in a new series of 32 patients with BCC. Most cases of superficial multicentric BCC and some nodular tumours had preserved expression of both cadherins in all tumour cells. The majority of nodular BCCs had partially reduced expression of one or both cadherins with an ordered distribution of cells showing different cadherin staining throughout the tumour mass. A severe reduction of E-CD expression with a disordered distribution of cells with different immunostaining intensity was observed in most specimens of infiltrative BCC. In contrast, P-CD expression was preserved in all cases of infiltrative BCC. These results suggest that P-CD and E-CD play different roles in the growth pattern of BCC. In addition, both anomalous P-CD expression and reduced E-CD expression were frequently observed in the spinous layer of epidermis overlying tumours. This phenomenon was significantly associated with the presence of keratinocytic atypia, which suggests that disturbed cadherin expression could be a marker of premalignant changes and/or hyperproliferative activity in human epidermis.

Aged↗
PubMed1995

Characteristics of urinary luteinizing hormone (LH) during the induction of LH surges of different magnitude in blood.

Urinary luteinizing hormone (LH) testing has been proposed as a reliable method for the prediction of ovulation but its accuracy has been challenged by some studies. To check how accurately the oscillations of urinary LH reflected the plasma changes, surges of LH of different magnitude and duration were artificially induced in plasma and the hormone was measured simultaneously in urine. Post-menopausal women (n = 16) were stimulated during 1 week with a combination of transdermal oestradiol (400 micrograms) and i.m. progesterone (25 mg on day 4, 50 mg on day 5) to obtain an LH discharge comparable with the pre-ovulatory LH peak. A short and moderate peak of LH was induced by the i.v. injection of 100 micrograms gonadotrophin-releasing hormone (GnRH) in six premenopausal women, whereas an LH discharge of higher amplitude and longer duration was induced by a single dose of 0.3 mg s.c. buserelin. The total urine production of the day was fractionated into 8 h periods. LH was measured by a commercial radioimmunoassay. Unambiguous peaks of LH were detected in the urine of all the women stimulated with either oestradiol plus progesterone or buserelin, but in only three out of the six women receiving GnRH. The urine LH reproduced the plasma changes of the hormone with short delay since the peaks were mostly detected in the same time fraction in which the serum discharge occurred.

Adult↗
PubMed1995

Sex selection may be inadvertently performed in in-vitro fertilization-embryo transfer programmes.

The present study aims to ascertain whether sex selection may be inadvertently performed in human in-vitro fertilization (IVF) and embryo transfer (IVF-embryo transfer) programmes when selecting for high quality embryos (those with the fastest cleaving rates and/or the best morphology) at the fresh transfer cycle. All patients entering into the study were treated with gonadotrophins after pituitary suppression with gonadotrophin-releasing hormone agonists (GnRHa) and had intrauterine embryo transfer on day 2 post-insemination. These patients were retrospectively divided into three groups according to whether the difference in mean number of cells between embryos transferred and all embryos available for transfer in a given cycle was less than (negative selection), equal to (no selection) or greater (positive selection) than zero. In cycles resulting in singleton births, the sex ratio of the resulting babies was significantly (P < or = 0.005) shifted toward the female (88.8%) and to the male (90.0%) in the negative and positive selection groups respectively. No shift in sex ratio was observed in cycles resulting in multiple births. Maternal age was another independent factor affecting sex ratio at birth. Sex ratio was significantly (P < or = 0.05) skewed in favour of males (62.7%) and females (71.4%) in women < 35 and > or = 35 years of age respectively. Maternal age, number of embryos transferred and the event of selecting or not selecting the slowest cleaving embryos for transfer were entered automatically in a three-group discriminant model for distinguishing cycles resulting in only boys, both boys and girls, and only girls. These data suggest that (i) sex selection may be inadvertently performed in IVF-embryo transfer programmes when selecting for high quality embryos at the fresh transfer cycles; (ii) human endometria may be favourable, indifferent or hostile to either fast cleaving or slow cleaving embryos depending on maternal age; and (iii) "natural' sex selection may be performed for social, psychological or medical reasons.

Adult↗
PubMed1995

G alpha q and G alpha 13 regulate NHE-1 and intracellular calcium in epithelial cells.

To understand the mechanisms by which G protein-coupled signaling systems regulate NHE-1 in epithelial cells, we expressed G alpha q and G alpha 13 in a renal epithelial cell line. We studied two signaling systems that have been implicated in NHE-1 regulation [intracellular Ca (Cai) and phospholipase C activity] and measured NHE-1 activity, mRNA, and antigen. Expression of alpha qWT and alpha qQ209L (a GTPase-deficient mutant) increased basal Cai and altered the kinetics of the bradykinin-induced Cai signal. The initial bradykinin-induced spike in Cai was prolonged and the plateau was higher in cells expressing alpha qWT and alpha qQ209L than in control cells. Cells expressing alpha 13WT also had a higher basal Cai and plateau after stimulation by bradykinin, but Ca release from intracellular stores was similar to that in control cells. Expression of all three alpha-chains increased NHE-1 activity, antigen, and mRNA. The alpha qQ209L had the greatest effect increasing activity by approximately twofold. The alpha 13WT increased NHE-1 activity by approximately 1.5-fold, and alpha qWT increased activity 1.2-fold. These studies demonstrate that alpha q and alpha 13 alter regulation of Cai but by different mechanisms. The Ca signal or another signal generated by alpha q and alpha 13 regulate(s) NHE-1 at the levels of activity, antigen, and mRNA.

Animals↗