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Biomedical subjects

C Castro

Publications and source records attributed to C Castro.

At least 73 records · Page 4Linked to original sources
PubMed1998

Proliferative effect of insulin on cultured smooth muscle cells from rat mesenteric resistance vessels.

The present study evaluates the growth promoting effect of insulin on the proliferative activity of cells from rat mesenteric arteries in culture in order to test the hypothesis that insulin may play a pathogenetic role in the hypertrophy of resistance vessels. The proliferative effect of insulin was studied in cultured vascular smooth muscle cells (SMC) obtained from two functionally different rat vessels: mesenteric arteries and aorta. Growth characteristics (cell number and growth rate) of mesenteric and aortic cells were determined after a quiescent period and followed-up for 24, 72, and 120 h after the addition of insulin. At all studied time intervals, aortic SMC exhibited a significatively higher cell number and specific growth rate than did mesenteric SMC. Aortic SMC also displayed a greater proliferation than did mesenteric SMC in the presence of 10% fetal calf serum (FCS). At a physiological concentration of 100 microU/mL, the proliferative effect of insulin, after a quiescent period, was seen only in aortic SMC, at 72 and 120 h. Higher insulin concentration (500 microU/mL) increased significantly the cell number in SMC of both arteries. The proliferative effect was significant at all studied periods for aortic SMC; however, in mesenteric SMC, insulin increased the cell number only at 72 and 120 h. The proliferative effect of insulin was observed on SMC obtained from functionally different arteries such as aorta and mesenteric, being greater in the former. The different behavior of these SMC in the presence not only of insulin, but also of 10% FCS, provides further evidence for the existence of intervascular heterogeneity. The mild stimulatory effect of insulin in vitro may contribute in this way to the vascular hypertrophy of pathological entities exhibiting hyperinsulinemia.

Animals↗
PubMed1998

The flanking region sequences of the 15-kDa lipoprotein gene differentiate pathogenic treponemes.

The species Treponema pallidum includes three subspecies (pallidum, pertenue, and endemicum) that cause syphilis, yaws, and bejel, respectively. A closely related species, Treponema paraluiscuniculi, is the etiologic agent of venereal syphilis in rabbits but does not infect humans. Although these treponemes cause distinct diseases, no laboratory method for differentiation has been reported. Genetic signatures were defined in the 5' and 3' flanking regions of the 15-kDa lipoprotein gene (tpp15) that distinguish the human pathogens and T. paraluiscuniculi, as well as distinguishing T. pallidum subsp. pallidum from the causes of human nonvenereal treponematoses. A single Eco47III restriction site in the 5' flanking region differentiates T. pallidum subsp. pallidum from the other subspecies and species, and an XcmI site in the 3' flanking region differentiates T. paraluiscuniculi from the human pathogens. Polymerase chain reaction methods and restriction polymorphism were used to analyze 27 strains of pathogenic Treponema species.

Animals↗
PubMed1998

Function and protective capacity of Treponema pallidum subsp. pallidum glycerophosphodiester phosphodiesterase.

Infectious syphilis, caused by the spirochete bacterium Treponema pallidum subsp. pallidum, remains a public health concern worldwide. The immune-response evasion mechanisms employed by T. pallidum are poorly understood, and prior attempts to identify immunoprotective antigens for subsequent vaccine design have been unsuccessful. Previous investigations conducted in our laboratory identified the T. pallidum glycerophosphodiester phosphodiesterase as a potential immunoprotective antigen by using a differential immunologic expression library screen. In studies reported here, heterologous expression of the T. pallidum glycerophosphodiester phosphodiesterase in Escherichia coli yielded a full-length, enzymatically active protein. Characterization of the recombinant molecule showed it to be bifunctional, in that it exhibited specific binding to human immunoglobulin A (IgA), IgD, and IgG in addition to possessing enzymatic activity. IgG fractionation studies revealed specific binding of the recombinant enzyme to the Fc fragment of human IgG, a characteristic that may play a role in enabling the syphilis spirochete to evade the host immune response. In further investigations, immunization with the recombinant enzyme significantly protected rabbits from subsequent T. pallidum challenge, altering lesion development at the sites of challenge. In all cases, animals immunized with the recombinant molecule developed atypical pale, flat, slightly indurated, and nonulcerative reactions at the challenge sites that resolved before lesions appeared in the control animals. Although protection in the immunized rabbits was incomplete, as demonstrated by the presence of T. pallidum in the rabbit infectivity test, glycerophosphodiester phosphodiesterase nevertheless represents a significantly immunoprotective T. pallidum antigen and thus may be useful for inclusion in an antigen cocktail vaccine for syphilis.

Animals↗
PubMed1998

A countrywide programme of continuing professional development in Argentina. Argentine Society of Paediatrics, Subcommittee of Continuing Paediatric Education.

The Argentinean Society of Paediatrics introduced in 1993 a continuing professional development (CPD) programme to raise standards of clinical practice. The aims of the project were to introduce a structured, distance learning programme accessible to all paediatricians in the country, but especially for those working far from centres of paediatric excellence. The programme is planned on an annual basis. It includes four activities: a written manual designed by a team of medical experts and educationalists comprising 12 topics; field work for participants; annual meetings in several locations in the country for discussion of the subjects; and an evaluation based on centrally designed multiple choice questions distributed by mail. In spite of a registration free of 90 Pounds a year, participation in the programme increased from 3357 in 1993 to 4126 in 1996, from a membership of 10 216 paediatricians in Argentina. The popularity of the programme may result from an appropriate interpretation of professional needs of paediatricians in Argentina, adequate organisational arrangements that reach all colleagues, including those working in remote areas, and a genuine motivation of paediatricians for participating in a learning process.

Argentina↗
PubMed1998

Relationship between ambulatory blood pressure monitoring and response of blood pressure in male hypertensive adolescents to exercise.

BACKGROUND: High blood pressure in the young has been related to the development of hypertension in adults; hence the importance of identifying adolescents with the risk of developing it.OBJECTIVE: To investigate the relationship between 24 h ambulatory blood pressure monitoring and the response of blood pressure in adolescents to exercise. DESIGN: A prospective and cross-sectional study. METHODS: We classified 101 men aged 13-18 years as obese hypertensive, lean hypertensive, obese normotensive, and lean normotensive. Mean blood pressure and variability were measured with ambulatory blood pressure monitoring, and expressed as 24 h, awake, and sleeping periods. Treadmill tests were also performed. RESULTS: Hypertensives and obese normotensives had higher ambulatory blood pressure monitoring values (P< 0.0001). Systolic blood pressure during sleep in obese subjects was significantly higher than that in lean usbjects (119.9 +/- 9 versus 113.6 +/- 8 mmHg, P < 0.001, obese hypertensives versus lean hypertensives; and 113.6 +/- 2 versus 103.0 +/- 2 mmHg, P < 0.002, obese normotensives versus lean normotensives) and nocturnal drop of systolic blood pressure was lower in obese subjects. We found a significant correlation between systolic blood pressure during ambulatory blood pressure monitoring and systolic blood pressure during moderate and maximal exercise for all periods (P < 0.0001). Blood pressure variability during awake period was higher in subjects with maximum exercise systolic blood pressure >/= 200 mmHg (7.4 +/- 2 versus 6.4 +/- 2%, P < 0.01).CONCLUSION: Systolic blood pressure measured by ambulatory blood pressure monitoring is related to response of systolic blood pressure to exercise and ambulatory blood pressure monitoring can identify groups of subjects at greater than normal risk through their higher blood pressure during sleep. Greater than normal blood pressure variability in adolescents is an indicator of the risk of reaching abnormal exercise values of systolic blood pressure. Higher casual blood pressure than ambulatory blood pressure monitoring values for adolescents should be considered abnormal.

Journal Article↗
PubMed1998

[Comparative study of the frequency and features of emotional disturbances in patients in primary care clinics].

BACKGROUND: Psychological problems are a frequent cause of consultation in primary care outpatient clinics. AIM: To report the results for Santiago de Chile of the World Health Organisation multicentric collaborative study on Psychological Symptoms in General Health Care. PATIENTS AND METHODS: The results of 1453 patients that attended three primary care clinics in East Metropolitan Santiago were compared with those of patients studied in 15 other centers throughout the world. Two hundred fifty three cases were studied in detail with a structured diagnostic interview (CIDI-PHC). The capacity of general physicians to recognise emotional disorders as well as their management of psychological cases was also assessed. RESULTS: Among the 253 patients studied in detail, 53% of patients had a definite psychiatric diagnosis, compared with 24% of patients, as an average, in other countries. There was a higher prevalence of depression, generalised anxiety disorder, neurasthenia and harmful use of alcohol. Chilean physicians recognised 74.1% of patients with psychiatric conditions, as compared with 48.9% of physicians abroad. Tranquilizing agents were the most often prescribed medications (40%) followed by antidepressants (18%). CONCLUSIONS: There is a high prevalence of emotional disorders in patients consulting at the primary care level.

Affective Symptoms↗
PubMed1998

[The role of external radiotherapy in the treatment of medullary carcinoma of the thyroid].

Medullary carcinoma of the thyroid represents 3 to 10% of all thyroid cancers. Surgery is the main treatment. External beam radiotherapy has a fundamental role in the treatment of residual disease following surgery, in cases of cervical node involvement, and in unresectable tumors. Between 1975 and 1993, 12 patients with medullary carcinoma of the thyroid were treated at the Department of Radiotherapy of the Portuguese Institute of Oncology in Oporto. Nine of these patients (75%) were male and 3 (25%) female, ranging from 24 to 80 years of age (mean = 43). All of them had residual tumor after surgery and underwent treatment with external beam radiotherapy. The follow-up period ranged from 36 to 180 months, with a median of 78 months; 8 patients (66.7%) are alive, 5 of them show no evidence of disease. Average survival was 70 months, and 4 patients (33%) died with metastatic disease. The aim of this paper is to analyse the role of external beam radiotherapy in local control of these tumors, with a brief review of the literature.

Adult↗
PubMed1997

Urinary calcium excretion in healthy school children.

Two hundred and twenty Argentinian primary school children (122 boys, 98 girls, aged 6-13 years) were studied to establish reference values of 24-h urinary calcium excretion (UCa) and calcium/creatinine ratio (Ca/Cr) in 24-h urine collections and in first-morning urine samples. Mean UCa excretion was 2.05 +/- 1.40 mg/kg per day and the 95th percentile was 4.74 mg/kg per day. UCa excretion was higher in boys than girls (2.33 +/- 1.47 and 1.70 +/- 1.24 mg/kg per day respectively, P < 0.001). Statistically significant differences were found between the 6- to 9-year and the 10- to 13-year age groups (2.37 +/- 1.49 vs. 1.73 +/- 1.25 mg/kg per day, P < 0.001). Mean Ca/Cr ratios in 24-h collections and in first-morning urine samples were 0.129 +/- 0.086 and 0.105 +/- 0.079 for the group overall (P < 0.001). The Ca/Cr ratio in the first-morning urine sample correlated poorly with the 24-h calcium excretion, suggesting that the Ca/Cr ratio in first-morning urine samples cannot replace the 24-h measurement.

Adolescent↗
PubMed1997

Species-specific voltage-gating properties of connexin-45 junctions expressed in Xenopus oocytes.

Gap junctions composed of connexin-45 (Cx45) homologs from four species, zebrafish, chicken, mouse, and human, were expressed in pairs of Xenopus oocytes. The macroscopic conductance (gj) of all Cx45 junctions was modulated by transjunctional voltage (Vj) and by the inside-outside voltage (Vm), and the modulation was species specific. Although their gating characteristics varied in voltage sensitivity and kinetics, the four Cx45 junctions shared 1) maximum conductance at Vj = 0 and symmetrical gj reduction in response to positive and negative Vj of low amplitude, with little residual conductance; and 2) gj increases in response to simultaneous depolarization of the paired cells. The formation of hybrid channels, comprising Cx45 hemichannels from different species, allowed us to infer that two separate gates exist, one in each hemichannel, and that each Cx45 hemichannel is closed by the negativity of Vj on its cytoplasmic side. Interestingly, the Vm dependence of hybrid channels also suggests the presence of two gates in series, one Vm gate in each hemichannel. Thus the Vj and Vm dependence provides evidence that two independent voltage gates in each Cx45 hemichannel exist, reacting through specific voltage sensors and operating by different mechanisms, properties that have evolved divergently among species.

Animals↗
PubMed1997

The value of hysteroscopic exploration for abnormal uterine bleeding.

STUDY OBJECTIVE: To determine sensitivity, specificity, positive predictive value, negative predictive value, and global diagnostic precision of hysteroscopic exploration in the diagnosis of endometrial hyperplasia and adenocarcinoma in women with abnormal uterine bleeding. DESIGN: Retrospective analysis. SETTING: University-affiliated hospital. PATIENTS: One thousand three hundred ninety-eight patients with abnormal uterine bleeding, 57.3% premenopausal and 42.6% postmenopausal. INTERVENTIONS: Diagnostic hysteroscopy and subsequent dilatation and curettage. MEASUREMENTS AND MAIN RESULTS: Endometrium was classified hysteroscopically as normal, atrophic, endometrial hyperplasia, and endometrial carcinoma. Histopathologic diagnosis was performed to determine the efficacy of hysteroscopy in diagnosing endometrial hyperplasia and adenocarcinoma. For endometrial hyperplasia in premenopausal women, sensitivity was 71.8%, specificity 96.4%, and global diagnostic precision 92.5%; in postmenopausal women, respective figures were 85. 1%, 100%, and 97.3%. For diagnosing adenocarcinoma in premenopausal patients, hysteroscopy was 100% sensitive, with specificity 99.4% and global diagnostic precision 99.5%; in postmenopausal women, respective figures were 100%, 99.4%, and 99.5%. CONCLUSIONS: In women with abnormal uterine bleeding, diagnostic hysteroscopy is a basic tool that allows precise diagnosis of endouterine lesions such as polyps and submucous myomas. It also is highly accurate for evaluating endometrial adenocarcinoma and hyperplasia.

Adenocarcinoma↗
PubMed1997

Conservation of the 15-kilodalton lipoprotein among Treponema pallidum subspecies and strains and other pathogenic treponemes: genetic and antigenic analyses.

The 15-kDa lipoprotein of Treponema pallidum is a major immunogen during natural syphilis infection in humans and experimental infection in other hosts. The humoral and cellular immune responses to this molecule appear late in infection as resistance to reinfection is developing. One therefore might hypothesize that this antigen is important for protective immunity. This possibility is explored by using both genetic and antigenic approaches. Limited or no cross-protection has been demonstrated between the T. pallidum subspecies and strains or between Treponema species. We therefore hypothesized that if the 15-kDa antigen was of major importance in protective immunity, it might be a likely site of antigenic diversity. To explore this possibility, the sequences of the open reading frames of the 15-kDa gene have been determined for Treponema pallidum subsp. pallidum (Nichols and Bal-3 strains), T. pallidum subsp. pertenue (Gauthier strain), T. pallidum subsp. endemicum (Bosnia strain), Treponema paraluiscuniculi (Cuniculi A, H, and K strains), and a little-characterized simian isolate of Treponema sp. (Fribourg-Blanc strain). No significant differences in DNA sequences of the genes for the coding region of the 15-kDa antigen were found among the different species and subspecies studied. In addition, all organisms showed expression of the 15-kDa antigen as determined by monoclonal antibody staining. The role of the 15-kDa antigen in protection against homologous infection with T. pallidum subsp. pallidum Nichols was examined in rabbits immunized with a purified recombinant 15-kDa fusion protein. No alteration in chancre development was observed in immunized, compared to unimmunized, rabbits, and the antisera induced by the immunization failed to enhance phagocytosis of T. pallidum subsp. pallidum by macrophages in vitro. These results do not support a major role for this antigen in protection against syphilis infection.

Animals↗
PubMed1997

bldA-dependent expression of the Streptomyces exfoliatus M11 lipase gene (lipA) is mediated by the product of a contiguous gene, lipR, encoding a putative transcriptional activator.

Extracellular lipase synthesis by Streptomyces lividans 66 carrying the cloned lipase gene (lipA) from Streptomyces exfoliatus M11 was found to be growth phase dependent, since lipase was secreted into the medium mainly during the stationary phase; S1 nuclease protection experiments revealed abundant lipA transcripts in RNA preparations obtained during the stationary phase but not in those obtained during exponential growth. Transcription from the lipA promoter was dependent on the presence of lipR, a contiguous downstream gene with a very high guanine-plus-cytosine content (80.2%). The deduced lipR product consists of a protein of 934 amino acids that shows similarity to known transcriptional activators and has a strong helix-turn-helix motif at its C terminus; this motif is part of a domain homologous to DNA-binding domains of bacterial regulators of the UhpA/LuxR superfamily. The lipR sequence revealed the presence of a leucine residue, encoded by the rare TTA codon, which caused bldA dependence of lipA transcription in Streptomyces coelicolor A3(2); replacement of the TTA codon by the alternate CTC leucine codon alleviated bidA dependence but not the apparent growth phase-dependent regulation of lipA transcription. When lipR expression was induced in a controlled fashion during the exponential growth phase, by placing it under the inducible tipA promoter, lipase synthesis was shifted to the exponential growth phase, indicating that the timing of lipR expression, and not its bldA dependence, is the main cause for stationary-phase transcription of lipA.

Amino Acid Sequence↗
PubMed1997

Detection of Treponema pallidum by a sensitive reverse transcriptase PCR.

Syphilis is diagnosed by serologic testing or by identification of the causative agent, Treponema pallidum. The bacterium has historically been detected in clinical specimens by dark-field microscopy, immunostaining with polyclonal or monoclonal antibodies, or the rabbit inoculation test (RIT). RIT is considered to be very sensitive and specific, although it is available only in research settings and is not clinically useful due to the length of time required to obtain a result. In recent years, several PCR methods have been developed for the detection of T. pallidum, but none of these has shown a clear advantage in sensitivity over RIT. We have developed a specific and highly sensitive reverse transcriptase PCR (RT-PCR) that targets a 366 bp region of the 16S rRNA of T. pallidum. This RT-PCR can detect a single organism by Southern analysis when whole organisms are diluted and 10(-2) to 10(-3) T. pallidum organisms when RNA equivalents are used to make cDNA. The test was demonstrated to detect 10(-2) T. pallidum RNA equivalents in cerebrospinal fluid. Twenty different strains of T. pallidum, isolated from cerebrospinal fluids, aqueous humor, blood, and chancres, were shown to be detectable by this test. This efficient and sensitive technique could be more useful than existing methods for detecting very low numbers of organisms in clinical samples.

DNA, Bacterial↗
PubMed1997

[Wine and health. Epidemiological studies and possible mechanisms of the protective effects].

Epidemiological studies show that moderate alcohol consumption, particularly wine, is associated to a decreased risk of ischemic heart disease death. A series of in vitro observations also support this association. Low density lipoproteins (LDL) oxidation apparently plays a key pathogenic role. Wine contains compounds with antioxidant capacity that could account for its postulated stabilizing effect on LDL. Furthermore, in human volunteers wine increases plasma total antioxidant capacity. Other additional effects also contribute to decrease the risk of ischemic heart disease: increased HDL cholesterol, and decreased blood coagulation. In another series of observations, moderate alcohol consumption has been associated with decreased physical and mental deterioration in elderly people. However, it is still under analysis if exaggerated alcohol consumption does increase the incidence of some cancers. On the whole, the presently available evidences clearly indicate that the positive effects associated to moderate wine or alcohol consumption, predominate over the negative effects. In fact, it seems reasonable to reassure moderate alcohol consumers that their cardiovascular death risk is lower; yet there are not enough studies to recommend moderate drinking to non-drinkers.

Adult↗
PubMed1996

Two 16S-23S ribosomal DNA intergenic regions in different Treponema pallidum subspecies contain tRNA genes.

The 16S-23S intergenic spacers of Treponema pallidum subspecies pallidum, Nichols strain, and Treponema pallidum subspecies pertenue, Gauthier strain, have been cloned, characterized and sequenced. Isoleucine and alanine tRNA genes have been identified within the 16S-23S intergenic regions on separate alleles of 293 and 303 bases, respectively. The two alleles are present in both T.p.pallidum and T.p. pertenue, and show no sequence differences between the bacterial subspecies. The ile-tRNA and ala-tRNA genes show 65% and 84% sequence identity, respectively, with the homologous genes of the related spirochete, Borrelia burgdorferi.

Alleles↗
PubMed1996

Isolation of a species-specific mitochondrial DNA sequence for identification of Tilletia indica, the Karnal bunt of wheat fungus.

Mitochondrial DNA (mtDNA) from five isolates of Tilletia indica was isolated and digested with several restriction enzymes. A 2.3-kb EcoRI fragment was chosen, cloned, and shown to hybridize with total DNA restricted with EcoRI from T. indica and not from a morphologically similar smut fungus, Tilletia barclayana. The clone was partially sequenced, and primers were designed and tested under high-stringency conditions in PCR assays. The primer pair Ti1/Ti4 amplified a 2.3-kb fragment from total DNA of 17 T. indica isolates from India, Pakistan, and Mexico. DNA from 25 isolates of other smut fungi (T. barclayana, Tilletia foetida, Tilletia caries, Tilletia fusca, and Tilletia controversa) did not produce any bands, as detected by ethidium bromide-stained agarose gels and Southern hybridizations. The sensitivity of the assay was determined and increased by using a single nested primer in a second round of amplification, so that 1 pg of total mycelial DNA could be detected. The results indicated that the primers which originated from a cloned mtDNA sequence can be used to differentiate T. indica from other Tilletia species and have the potential to identify teliospores contaminating wheat seeds.

Base Sequence↗
PubMed1996

Progesterone does not alter sympathetic activity in tissues involved in energy balance.

Female rats acclimated to thermoneutrality to avoid cold influences received progesterone by means of subcutaneous implants. They increased their food intake and body weight above the values recorded in control animals. None the less, despite the enhanced food intake, no sign of activation of the sympathetic nervous system was observed, as judged by the unaltered noradrenaline content, half-life and turnover rate in brown adipose tissue, pancreas and heart. This indicates that progesterone increases food intake but prevents non-energy-conservation processes regulated by the sympathetic nervous system from taking place. Thus, it facilitates in two different ways the building up of energy stores. Because overfeeding induced by palatable diets increases the sympathetic tone to the organs studied, it is suggested that the central mechanisms regulating energy balance are probably influenced in a different manner by progesterone than by the sensory properties of palatable diets.

Adipose Tissue, Brown↗