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Biomedical subjects

R Castro

Publications and source records attributed to R Castro.

At least 37 records · Page 2Linked to original sources
PubMed2000

Novel ferrocenyl polyene derivatives and their binding to unmodified cyclodextrins

Two new ferrocene derivatives, 7-ferrocenyl-2,4,6-heptatrienal (1) and 7-ferrocenyl-2,4,6-heptatrienol (2), were synthesized and characterized. These two compounds possess a rigid triene chain conjugated to one of the cyclopentadienyl rings of the ferrocene residue, and as a result, they exhibit very stiff structures. The electronic absorption and electrochemical properties of these compounds were utilized to investigate their host-guest binding interactions with the receptors alpha-cyclodextrin (alpha-CD) and beta-cyclodextrin (beta-CD) in aqueous solution. From electronic absorption measurements binding constants in the range 790-12900 M(-)(1) were obtained; beta-CD formed more stable complexes than alpha-CD with both guests. Electrochemical measurements suggest some degree of site selectivity in the complexation processes, with beta-CD binding preferentially to the ferrocene moiety while alpha-CD interacts with the unsaturated chain.

Journal Article↗
PubMed2000

On-line ion-pair solid-phase extraction-liquid chromatography-mass spectrometry for the analysis of quaternary ammonium herbicides.

An ion-pair on-line solid-phase extraction procedure using C8 extraction disks, suitable for liquid chromatography-mass spectrometry analysis is developed to determine quaternary ammonium herbicides (quats) in water samples. The separation of these compounds was performed using ion-pair chromatography with heptafluorobutyric acid (15 mM, pH 3.3) and acetonitrile gradient elution. Detection was carried out using a quadrupole mass spectrometer. Water sample volumes up to 50 ml can be preconcentrated with recoveries higher than 70%. Good precision and accuracy (day-to-day and run-to-run) were obtained and the detection limits ranged from 6 to 85 ng l(-1). The proposed on-line ion-pair solid-phase method enables compliance with European Community directives for drinking waters (100 ng l(-1)).

Chromatography, Liquid↗
PubMed2000

Regulation of (1-3)-beta-glucan-stimulated Ca(2+) influx by protein kinase C in NR8383 alveolar macrophages.

Stimulation of (1-3)-beta-glucan receptors results in Ca(2+) influx through receptor-operated channels in alveolar macrophages (AMs), but the mechanism(s) regulating Ca(2+) influx is still undefined. In this study we investigated the role of protein kinase C (PKC) regulation of Ca(2+) influx in the NR8383 AM cell line using the particulate (1-3)-beta-glucan receptor agonist zymosan. PKC inhibition with calphostin C (CC) or bisindolymaleimide I (BSM) significantly reduced zymosan-induced Ca(2+) influx, whereas activation of PKC with phorbol-12-myristate 13-acetate (PMA) or 1, 2-dioctanoyl-sn-glycerol (DOG) mimicked zymosan, inducing a concentration-dependent Ca(2+) influx. This influx was dependent on extracellular Ca(2+) and inhibited by the receptor-operated Ca(2+) channel blocker SK&F96365, indicating that zymosan and PKC activate Ca(2+) influx through a similar pathway. NR8383 AMs expressed one new PKC isoform (delta) and two atypical PKC isoforms (iota and lambda), but conventional PKC isoforms were not present. Stimulation with zymosan resulted in a translocation of PKC-delta from the cytosol to the membrane fraction. Furthermore, inhibition of protein tyrosine kinases (PTKs) with genistein prevented zymosan-stimulated Ca(2+) influx and PKC-delta translocation. These results suggest that PKC-delta plays a critical role in regulating (1-3)-beta-glucan receptor activated Ca(2+) influx in NR8383 AMs and PKC-delta translocation is possibly dependent on PTK activity.

Animals↗
PubMed2000

Echovirus 7 infection and necrotizing enterocolitis-like symptoms in a premature infant.

Echovirus type 7 has been previously recognized as a virulent serotype in the premature neonate. However, reports of fatal disseminated infections have often been perinatally acquired from symptomatic mothers at the time of delivery. Nosocomial outbreaks in full-term and premature infants have been reported from newborn intensive care units; however, deaths attributed to Echovirus 7 in convalescing prematures are rare in the literature. We report the case of a growing premature neonate presenting with an overwhelming sepsis-like syndrome, including symptoms consistent with necrotizing enterocolitis. Despite intensive supportive care including ventilatory support, cardiovascular pharmacotherapy, and blood product administration, the infant succumbed to overwhelming Echovirus 7 infection.

Echovirus Infections↗
PubMed2000

Ion transport in an immortalized rat submandibular cell line SMG-C6.

The immortalized rat submandibular epithelial cell line, SMG-C6, cultured on porous tissue culture supports, forms polarized, tight-junction epithelia facilitating bioelectric characterization in Ussing chambers. The SMG-C6 epithelia generated transepithelial resistances of 956+/-84Omega.cm2 and potential differences (PD) of -16.9 +/- 1.5mV (apical surface negative) with a basal short-circuit current (Isc) of 23.9 +/- 1.7 microA/cm2 (n = 69). P2 nucleotide receptor agonists, ATP or UTP, applied apically or basolaterally induced a transient increase in Isc, followed by a sustained decreased below baseline value. The peak DeltaIsc increase was partly sensitive to Cl- and K+ channel inhibitors, DPC, glibenclamide, and tetraethylammonium (TEA) and was completely abolished following Ca2+ chelation with BAPTA or bilateral substitution of gluconate for Cl-. The major component of basal Isc was sensitive to apical Na+ replacement or amiloride (half-maximal inhibitory concentration 392 nM). Following pretreatment with amiloride, ATP induced a significantly greater Isc; however, the poststimulatory decline was abolished, suggesting an ATP-induced inhibition of amiloride-sensitive Na+ transport. Consistent with the ion transport properties found in Ussing chambers, SMG-C6 cells express the rat epithelial Na+ channel alpha-subunit (alpha-rENaC). Thus, cultured SMG-C6 cells produce tight polarized epithelia on permeable support with stimulated Cl- secretory conductance and an inward Isc accounted for by amiloride-sensitive Na+ absorption.

Adenosine Triphosphate↗
PubMed2000

Takayasu's arteritis associated with Crohn's disease. Report of a case.

The authors report a rare case of Takayasu's arteritis with aortic arch and abdominal aorta involvement associated with Crohn's disease of the colon which both occurred in a young female patient. The coexistence of two immune mediated diseases in the same subject is unusual for they are generally considered to be independent of each other, however a hypothesis of their possible interrelationship is put forward.

Adult↗
PubMed1999

Ion-pair liquid chromatography--atmospheric pressure ionization mass spectrometry for the determination of quaternary ammonium herbicides.

High-performance liquid chromatography coupled with atmospheric pressure ionization mass spectrometry (electrospray and atmospheric pressure chemical ionization) has been used to characterize some quaternary ammonium herbicides (quats). The separation of these compounds was carried out using ion-pair chromatography with heptafluorobutyric acid (15 mM, pH 3.3) and acetonitrile gradient elution for successful coupling to mass spectrometry. Detection limits down to 0.1-4 micrograms l-1 were obtained for spiked tap water following a preconcentration step. Good reproducibilities (day-to-day and run-to-run) were also obtained.

Atmospheric Pressure↗
PubMed1999

Complete resolution of post-traumatic high-flow priapism with conservative treatment.

The most frequent cause of high-flow priapism is penile or perineal closed trauma with laceration of the cavernous artery and the formation of an arterial-lacunar fistula. We present the case of a high-flow priapism due to closed perineal trauma and damage to the left cavernous artery which completely resolved following conservative treatment. The case was documented by duplex Doppler ultrasound and selective pudendal arteriogram before and after resolution.

Adult↗
PubMed1999

A case of neurofibromatosis type 1 with an aldosterone-producing adenoma of the adrenal.

Neurofibromatosis type 1 is a phacomatosis. Neurofibromas are the most common tumours associated with the disease, and along with other tumours, make neurofibromatosis type 1 the most common tumour predisposing syndrome in humans. Hypertension may be coincidental, but at least two specific neurofibromatosis related causes must be considered, namely neurofibromatous involvement of the renal artery and pheochromocytoma. We have described the first known case of a patient with neurofibromatosis type 1 who developed hypertension due to an aldosterone-producing adenoma of the adrenal. The question of whether this association was coincidental or due to the tumour predisposition of neurofibromatosis type 1 was debated.

Adenoma↗
PubMed1999

Prevalence of hepatitis viruses in an anti-human immunodeficiency virus-positive population from Argentina. A multicentre study.

The objectives of this study were to investigate the prevalence of infections with hepatotrophic viruses in an anti-human immunodeficiency virus (HIV)-positive population from Buenos Aires and to compare it among the main risk groups for HIV infection. Four hundred and eighty-four consecutive patients attending the HIV outpatients clinic were studied: 359 men and 125 women, median age 29 years (range 16-67 years); 35.5% had presented acquired immune deficiency syndrome (AIDS)-defining conditions. Two hundred and thirty-four patients were intravenous drug users (IVDU), 99 had homosexual and 142 heterosexual preference, seven had received blood transfusions and two had no risk factors. Hepatitis B surface antigen (HBsAg), and antibodies to hepatitis B core antigen (HBcAb) and to hepatitis C virus (anti-HCV) were investigated in all patients; antibodies to HBsAg (HBsAb) and IgG antibodies to hepatitis D virus (anti-HDV) in all HBcAb-positive patients; hepatitis B e antigen and antibodies to HBeAg (HBeAg) in all HBsAg-positive patients; IgG antibodies to hepatitis A virus (anti-HAV) in the first 307 patients; and IgG antibodies to hepatitis E virus (anti-HEV) in the first 91 patients. As control groups, contemporary voluntary blood donors were studied for prevalence of HAV, HBV, HCV and HEV. The percentages of HBcAb, HBsAg, anti-HCV and anti-HEV (58.5, 14.5, 58.5 and 6.6%, respectively) were significantly higher in anti-HIV-positive patients than in control groups (3.2, 0.5, 1.0 and 1.8%, respectively) (P = 0.000). The prevalence of HBcAb was significantly higher in IVDU (72.6%) than in heterosexuals (33.8%) (P = 0.0001) and in homosexuals (59.6%) (P = 0.0189). The percentage of HBsAg was significantly higher in IVDU (19.2%) than in heterosexuals (6.3%) (P = 0.0004). Anti-HCV was significantly higher in IVDU (92.3%) than in homosexuals (14.1%) and in heterosexuals (33.1%) (P = 0.000 in both cases). The prevalence of anti-HDV was relatively low (1.9%). There was no difference in the percentage of anti-HAV between HIV-positive and negative subjects. In conclusion, there is a high prevalence of HBV and HCV infections in HIV-positive patients from our area. Drug use is the main route of transmission, but prevalence of HCV in patients with, probably, sexually acquired HIV infection is also higher than in the control group. The increased prevalence of HEV infection in HIV-positive individuals is another provocative finding that warrants further study.

Adolescent↗
PubMed1999

Barriers to early detection of cervical-uterine cancer in Mexico.

In Mexico, a woman dies of cervical-uterine cancer every 2 hours, indicating a low impact by the national program for early detection of this cancer, principally because of problems related to quality and coverage. Through a qualitative study, we identified the principal barriers to use of the detection program from the point of view of actual and potential program users. Four focus groups were organized in standard conditions in Mexico City (urban, developed) and in the southern state of Oaxaca (rural, economically disadvantaged area). Participants were either women with at least one previous Papanicolaou (Pap) test or women who had never had the test. Barriers to Pap test use included (1) lack of knowledge about cervical-uterine cancer etiology, (2) not knowing that the Pap test exists, (3) the conception that cancer is an inevitably fatal disease, (4) problems in doctor/medical institution-patient relationships, (5) giving priority to unmet needs related to extreme poverty, (6) opposition by the male sexual partner, (7) rejection of the pelvic examination, (8) long waits for sample collection and receiving results, and (9) perceived high costs for care. To increase coverage of the early detection program for cervical-uterine cancer in Mexico, the needs, perceptions, and beliefs of women and their partners must be taken into account when developing policy and planning, given the role these factors play in the decision-making process that leads to their participation or nonparticipation in this program.

Adult↗
PubMed1999

[Tularemia: considerations on a new case in the Monte Amiata].

One sporadic case of tularemia induced by direct contact with an infected hare is described. Human epidemiological data of the last ten years in Tuscany, emphasize that this infection, although at low incidence, shows the presence and persistence of Francisella tularensis in the animals and the ensuing transmission to humans so that it continues to be responsible for significant morbididy in "at risk" territories. Difficulties in the differential diagnosis, above all for glandular and pharyngeal forms, are reviewed.

Humans↗
PubMed1998

Hepatitis C virus genotypes and the influence of the induction of immunosuppression with anti-thymocyte globulin (ATG) on chronic hepatitis in renal graft recipients.

Hepatitis C virus (HCV) exhibits a dramatic genetic variability and several mechanisms of immunological response are unable to control hepatic and extrahepatic replication. Genotype 1 b is associated with more severe clinical manifestations and is less responsive to interferon. In addition, we have reported an increase of HCV RNA viral load after renal transplantation. Anti-thymocyte globulin (ATG) is supposed to increase viral replication and liver dysfunction in chronically infected renal graft recipients. We evaluated the genotype profile in HCV+ patients of our Renal Transplant Unit and studied the effects of ATG, as part of the induction of immunosuppression, on viral load and liver enzymes abnormalities. From 726 renal graft recipients, 104 patients, with a mean follow up of 3.9 +/- 2.9 years, were anti-HCV+ by ELISA II. HCV RNA was measured by quantitative PCR. We correlated the viral load and biochemical liver parameters with genotype, exposure to ATG as induction therapy, early acute rejection episode and the duration of infection. Of the 81 patients tested, 72% were viraemic and genotype 1 b was the predominant viral strain (66%). The majority of these patients (65%) were coinfected by two or more strains. There was no correlation between HCV RNA blood levels and liver enzymes. We did not find higher viral load with genotype 1 b infection (68 +/- 88 mEq/ml vs 75.8 +/- 123 mEq/ml in the others) nor with ATG induction therapy (43.5 +/- 71.3 mEq/ml vs 64.1 +/- 110.5 mEq/ml). Early acute rejection and longer follow up were not associated with higher levels of HCV RNA. The biochemical liver profile showed no relationship with the variables studied. We concluded that genotype 1 b is the predominant strain in our HCV+ population and there is a great prevalence of coinfection with several genotypes. Our results did not confirm a deleterious effect of the use of ATG as induction therapy in these HCV-infected patients. Prospective randomised studies with liver biopsy evaluation are needed to answer more fully the remaining questions about the best immunosuppressive therapy in renal graft recipients with chronic HCV infection.

Genotype↗
PubMed1998

Risk of Helicobacter pylori transmission by upper gastrointestinal endoscopy.

BACKGROUND: Upper gastrointestinal endoscopy has been reported as a risk factor for the transmission of Helicobacter pylori. The aim of this study was to evaluate the possibility of transmission of H. pylori infection by upper gastrointestinal endoscopy in patients who had previously had such procedures in a low disinfection level environment. METHODS: The study included 1082 patients. Patients that had undergone upper gastrointestinal endoscopy or were treated with antibiotics 15 days before the index endoscopy were excluded. H. pylori infection was diagnosed by ultra-rapid urease test. Variables analyzed were age, gender, type of dyspepsia (organic or functional), and the number of previous upper gastrointestinal endoscopies. RESULTS: Overall prevalence of H. pylori infection was 60%. Patients ranged in age from 13 to 94 years (mean = 45.8, SD = 15.7) and the number of previous upper gastrointestinal endoscopies ranged from 0 to 20 (mean = 1.5, SD = 2.4). In 53.3% of the patients, upper gastrointestinal endoscopy revealed some mucosal lesion (organic dyspepsia). Prevalence of H. pylori infection was higher in patients with organic rather than functional dyspepsia (71.1% vs. 47.1%, p < 0.001). There was no statistically significant difference in the mean number of upper gastrointestinal endoscopies in patients with and without H. pylori infection. CONCLUSIONS: We concluded that there was no association between history of upper gastrointestinal endoscopy and current H. pylori infection in this study population.

Adolescent↗
PubMed1998

Family responses to HIV/AIDS in Mexico.

This paper presents findings from a qualitative study of household and community responses to HIV/AIDS in Mexico. Fieldwork took place in two contrasting settings: (a) Ciudad Netzahualcóyotl, a socially marginalized urban community and (b) the homosexual community of Mexico City, a sexually marginalized social network. 113 in-depth interviews were conducted with people with HIV/AIDS, their relatives and members of their social networks. This paper describes findings from interviews conducted with family members of persons with AIDS. Four stages of response are identified and characterized within each community: (i) life before AIDS, (ii) life during the discovery of AIDS, (iii) living with a person with AIDS and (iv) surviving those who have died from AIDS. The social marginalization of both communities is central in explaining how families respond to the disease. In Ciudad Netzahualcoyotl, social support derives from a local culture of kinship. In the gay community, on the other hand, solidarity arises out of friendship. Between social support and discrimination, many more "ambivalent" behaviours (neither fully supportive nor discriminating) are displayed by family members and friends. Fear, pre-existing family conflicts and prejudice nurture these negative responses. Family responses and the processes to which they give rise, also differ depending on whether or not a male or female household member is affected. Policy recommendations are made concerning how best to promote positive family and household responses to persons with HIV/AIDS and how to inhibit negative ones.

Acquired Immunodeficiency Syndrome↗