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Biomedical subjects

S Silva

Publications and source records attributed to S Silva.

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

[Diagnosis of a cardiac mass--a case report].

The authors describe a case of a recidivant pericardial effusion associated to a mass with an unusual, filamentous aspect that involved the upper part of right atrium and surrounded the upper vena cava. Despite the diagnostic techniques employed--transesophageal echocardiography and magnetic resonance imaging, the etiologic diagnosis could not be done, so a biopsy of the mass was made by percutaneous approach using transesophageal echocardiography to control the procedure. The histopathological result was an angiosarcoma of the right atrium. The authors make a brief review of the literature about this rare condition.

Echocardiography, Transesophageal↗
PubMed1999

Hydrophobic interaction chromatography of Chromobacterium viscosum lipase on polypropylene glycol immobilised on Sepharose.

The fractionation of Chromobacterium viscosum lipase was performed using a polypropylene glycol-Sepharose gel. The influence of mobile phase composition on the adsorption of lipase on the gel was studied and it was found that the retention of lipase depends on the salt used and increased with increasing the ionic strength. The retention was not strongly affected by changing the pH value of the mobile phase. By using 20% (w/v) ammonium sulphate in phosphate buffer a total retention of lipase on the column was obtained and by simply decreasing the ionic strength of the buffer, desorption of lipase could be achieved. The chromatographic purification of Chromobacterium viscosum lipase by hydrophobic interaction chromatography on Sepharose CL-6B modified by covalent immobilisation of 1,4-butanediol diglycidyl ether, polyethylene glycol and polypropylene glycol was also compared.

Butylene Glycols↗
PubMed1999

Plasmacytoma induction in specific pathogen-free (SPF) bcl-2 transgenic BALB/c mice.

Germ-free (GF) and specific pathogen free (SPF) BALB/c mice are refractory to plasmacytoma induction by pristane (McIntire and Princler, 1969, Byrd et al 1991). It was therefore suggested that MPC development may depend on antigenic stimulation. If so, it may conceivably act by preventing the apoptotic elimination of tumor precursor cells. We have tested this idea by elevating the apoptotic threshold by the introduction of a bcl-2 transgene. We have found that MPCs could be induced by pristane oil in transgene carrying SPF mice. An E mu activated bcl-2 transgene was introduced into SPF BALB/c mice. The mice were used after two backcrosses (BC-2). Pristane oil treatment was started at 4 to 6 weeks of age (3 x 0.3 ml via i.p. at monthly intervals). For each transgene carrier a transgene negative littermate was used as control. Fifteen of 24 (63%) transgene carriers developed plasmacytomas after latency periods between 67 and 146 days (mean = 112 +/- 30 days) after the first pristane injection. Five additional transgene carriers developed lymphoma (3 cases) or mixed MPC and lymphoma (2 cases). In contrast, no tumors developed in 16 transgene negative littermates that were kept > 300 days under observation. Karyotyping showed that 10/15 (66%) of the MPCs carried a T(12;15) translocation, 4/15 (27%) carried both T(12;15) and T(6;15) translocations in the same metaphase plate, and 1/15 (7%) was translocation free. A T(12;15) translocation was also detected in one of the 2 mice with mixed tumor type. Pristane treated bcl-2 transgenic C57B1/6 mice remained tumor free, although T(12;15) translocation carrying cells were found in the peritoneal fluid of 4/20 mice 176 days after pristane.

Animals↗
PubMed1999

WAY 100635, a 5-HT1A receptor antagonist, prevents the impairment of spatial learning caused by blockade of hippocampal NMDA receptors.

We studied the effect of WAY 100635, a 5-HT1A receptor antagonist, on the impairment of spatial learning caused by intrahippocampal injection of 3-((R)-2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP), a competitive NMDA receptor antagonist, in a two-platform spatial discrimination task. CPP, 3 and 10 ng/microl, administered bilaterally into the CA1 region of the dorsal hippocampus 10 min before each training session, dose-dependently reduced choice accuracy in the two-platform spatial discrimination task with little or no effect on choice latency and errors of omission. A volume of 10 ng/microl intrahippocampal CPP did not affect choice accuracy or latency of a non-spatial visual discrimination task. Subcutaneous doses of 0.3 and 1 mg/kg WAY 100635 did not modify the choice accuracy, but prevented the impairment caused by 10 ng/microl intrahippocampal CPP. A dose of 20 ng/microl WAY 100635 into the dorsal hippocampus prevented the deficit caused by 10 ng/microl CPP administered in the same region. The results suggest that blockade of 5-HT1A receptors can compensate the loss of NMDA-mediated excitatory input to pyramidal cells in the hippocampus. These findings may have clinical relevance for the symptomatic treatment of memory disorders associated with reduced glutamate transmission mediated by NMDA receptors.

Animals↗
PubMed1999

Prenatal diagnosis of alobar holoprosencephaly at 10 weeks of gestation.

Alobar holoprosencephaly is an intracranial abnormality characterized by failure of proper cleavage of the prosencephalon, accompanied by incomplete midfacial development. The prenatal sonographic diagnosis of alobar holoprosencephaly was first described in 1984; however, there have been only two reports of alobar holoprosencephaly diagnosed in the first trimester. We report a case of alobar holoprosencephaly diagnosed at 10 weeks of gestation.

Abortion, Therapeutic↗
PubMed1999

Assessing the feasibility of linkage disequilibrium methods for mapping complex traits: an initial screen for bipolar disorder loci on chromosome 18.

Linkage disequilibrium (LD) analysis has been promoted as a method of mapping disease genes, particularly in isolated populations, but has not yet been used for genome-screening studies of complex disorders. We present results of a study to investigate the feasibility of LD methods for genome screening using a sample of individuals affected with severe bipolar mood disorder (BP-I), from an isolated population of the Costa Rican central valley. Forty-eight patients with BP-I were genotyped for markers spaced at approximately 6-cM intervals across chromosome 18. Chromosome 18 was chosen because a previous genome-screening linkage study of two Costa Rican families had suggested a BP-I locus on this chromosome. Results of the current study suggest that LD methods will be useful for mapping BP-I in a larger sample. The results also support previously reported possible localizations (obtained from a separate collection of patients) of BP-I-susceptibility genes at two distinct sites on this chromosome. Current limitations of LD screening for identifying loci for complex traits are discussed, and recommendations are made for future research with these methods.

Bipolar Disorder↗
PubMed1998

Resting blood pressure and thermal pain responses among females: effects on pain unpleasantness but not pain intensity.

In order to investigate the influence of resting blood pressure on thermal pain responses among females, this experiment studied 21 pain-free, normotensive females (mean age 23) classified as having high (HBP) vs. low blood pressure (LBP) based on a median split of resting blood pressure collected prior to thermal testing. All subjects then underwent thermal pain testing, including determination of pain threshold and tolerance followed by verbal descriptor ratings of the intensity and unpleasantness of suprathreshold thermal stimuli, ranging from 45 to 49 degrees C. Thermal stimuli were delivered to the volar forearm and the ipsilateral face using a 1 cm2 contact thermode. Results indicated that the blood pressure groups did not differ in thermal pain threshold or tolerance or on ratings of the intensity of suprathreshold thermal stimuli. However, the HBP group provided significantly lower ratings of thermal pain unpleasantness than the LBP group (P < 0.01). These data indicate that resting blood pressure is inversely associated with pain sensitivity among females, but this relationship may be selective for the affective component of pain.

Adolescent↗
PubMed1998

Sensitivity of patients with painful temporomandibular disorders to experimentally evoked pain: evidence for altered temporal summation of pain.

Temporomandibular disorders (TMD) represent a group of chronic painful conditions involving the muscles of mastication and the temporomandibular joint. Several studies have reported that TMD is associated with enhanced sensitivity to experimental pain. Twenty-three TMD subjects and 24 pain-free matched control subjects participated in a set of studies which were designed to evaluate whether the temporal integrative aspects of thermal pain perception are altered in TMD patients compared with control subjects. Specifically, we have examined in both TMD patients and in age- and gender-matched control subjects: (1) the time-course and magnitude of perceived pain evoked by the application of sustained 7-s noxious thermal stimuli (45-48 degrees C) to the face and forearm, (2) the central summation of C-fiber-mediated pain produced by applying brief trains of noxious heat pulses to the skin overlying the ventral aspect of the right palm and (3) the ability to discriminate small increments in noxious heat applied to facial and volar forearm skin. Data collected from these studies indicate that TMD patients show enhanced temporal integration of thermal pain compared with control subjects. TMD patients show greater thermal C-fiber-mediated temporal summation than pain-free subjects and they report a greater magnitude of sustained noxious heat pulses applied to either the face or the forearm than control subjects. In contrast to these findings, TMD and pain-free subjects are equally able to discriminate and detect small increments of heat applied to noxious adapting temperatures. These findings suggest that the augmented temporal integration of noxious stimuli may result from alterations in central nervous system processes which contribute to the enhanced pain sensitivity observed in TMD patients.

Adolescent↗
PubMed1998

CSF, plasma viral load and HIV associated dementia.

Plasma viral burden has proven valuable in predicting the future course of systemic HIV related disease and the response to treatment. It is not known whether plasma or cerebrospinal fluid (CSF) viral burden can be used to predict onset of or response to treatment of nervous system disease. We propose a model of viral load mediated neurotoxicity underlying peripheral and central HIV associated neurological disease. The objective of this preliminary study was to assess the relationship of HIV associated neurological disease to quantitative viral load in plasma and CSF. 47 subjects (HIV- = 10, HIV+ = 37) participated in the study. Plasma and CSF samples were collected within a 3 h window. RT-PCR (Roche Amplicor Monitor) was utilized to assess HIV-1 RNA viral load in both plasma and cell free (centrifuged) CSF. Subjects underwent concurrent comprehensive neurological and neuropsychological evaluations. In general, systemic viral load, as measured in plasma, was greater than that found in cell free CSF. Cell free CSF HIV RNA viral load was significantly correlated with neurological dysfunction, whereas plasma viral load was not. The sole subject with an elevated CSF viral load (> 5 Log 10), had HIV associated dementia (HAD) on clinical examination.

AIDS Dementia Complex↗
PubMed1997

Prognostic markers for colorectal cancer: expression of P53 and BCL2.

P53 is a tumor suppressor gene that has been implicated in the pathogenesis of a wide range of tumor types including colorectal cancers. bcl2 is a proto-oncogene that inhibits apoptosis. Immunostaining for P53 and BLC2 protein product was performed in a retrospective series of 80 colorectal carcinomas with a minimum follow-up of 5 years. The aim of the study was to evaluate the prognostic significance of P53 and BCL2 protein expression and their correlation with clinicopathologic variables such as pathologic disease stage (Dukes system), histologic grade, and vascular invasion. The patients were 41 to 76 years of age, and the follow-up ranged between 5 and 10 years. Among the 80 cases, 30 were Dukes stage A and 50 stage B. We found vascular invasion in 21.2%. P53 and BCL2 expression was detected, respectively, in 30.0% and 8.8%. We concluded that the P53 and BCL2 expression detected by immunohistochemistry in routinely processed, paraffin-embedded tissues: (1) has no prognostic significance; and (2) was not correlated with pathologic disease stage, histologic grade, or vascular invasion. Nevertheless, the number of patients in our study was small, and we believe that investigation of a larger series of patients is indicated.

Adult↗
PubMed1997

Spontaneous development of plasmacytomas in a selected subline of BALB/cJ mice.

Sixty per cent of BALB/cAnPt mice injected intraperitoneally (i.p.) with tetramethylpentadecane (pristane) develop plasmacytomas (PCs), whereas less than 10% of BALB/cJ develop such tumours. Most other mouse strains are completely resistant. Resistance is dominant over susceptibility in F1 hybrids between BALB/cAnPt and the resistant non-BALB/c strains, suggesting that susceptibility may be due to some genetic defect. (BALB/cAnPtxBALB/cJ)F1 hybrids have a PC incidence of 36-42%. Previously, BALB/cJ has been shown to harbour at least one resistance gene (Potter et al., Genomics 1988, Vol. 2, pp. 257-262). On the assumption that BALB/cJ may contain a segregating resistance gene, we cross BALB/cJ females with pristane-pretreated BALB/cJ males that were found to be carrying PC cells intraperitoneally 5-7 months after pristane treatment. After two selective crosses, 62% of the BALB/cJ subline BALB/cM2/22 developed PC after pristane and 52% after pristane followed by Abelson virus, while unselected controls had an incidence of 11% and 0%, respectively. Moreover, six spontaneous plasmacytomas developed in untreated females of the selected colony. Five of these carried T(12; 15) (F2; D2/3) translocations. The sixth had a T(1; 10) (G; C1) translocation and an interstitial duplication of segment (C1/E3) on one chromosome 5. It may be concluded that pristane treatment is not a prerequisite for the induction of the PC associated Ig/myc translocations.

Animals↗
PubMed1997

[The alcohol-dependent outpatient: a clinical typology].

The aim of this study was to construct a typology integrating sociodemographic, clinical and personality data of alcohol-dependent patients. We studied a consecutive population attending an alcohol-dependent outpatient psychiatric department, assessed by instruments that measured psychiatric, psychopathological, personality and sociodemographic characteristics of alcohol-dependent patients. The factorial analysis allowed us to define three main expressions of alcoholism: physical, psychological and social. In the elicited typology, both physical and social appear mixed in their expression. The psychological expression is divided into two main categories: the alexithymic (with a depressive personal and family history) and the psychopathologic type (with actual depression and anxiety). This typology should allow us to correlate these types with neurophysiological and biochemical patterns and could be particularly useful in building an etiologic model of alcohol dependence which could contribute to a better prediction of prognosis and choice of the best therapeutic intervention.

Adult↗
PubMed1996

A complete genome screen for genes predisposing to severe bipolar disorder in two Costa Rican pedigrees.

Bipolar mood disorder (BP) is a debilitating syndrome characterized by episodes of mania and depression. We designed a multistage study to detect all major loci predisposing to severe BP (termed BP-I) in two pedigrees drawn from the Central Valley of Costa Rica, where the population is largely descended from a few founders in the 16th-18th centuries. We considered only individuals with BP-I as affected and screened the genome for linkage with 473 microsatellite markers. We used a model for linkage analysis that incorporated a high phenocopy rate and a conservative estimate of penetrance. Our goal in this study was not to establish definitive linkage but rather to detect all regions possibly harboring major genes for BP-I in these pedigrees. To facilitate this aim, we evaluated the degree to which markers that were informative in our data set provided coverage of each genome region; we estimate that at least 94% of the genome has been covered, at a predesignated threshold determined through prior linkage simulation analyses. We report here the results of our genome screen for BP-I loci and indicate several regions that merit further study, including segments in 18q, 18p, and 11p, in which suggestive lod scores were observed for two or more contiguous markers. Isolated lod scores that exceeded our thresholds in one or both families also occurred on chromosomes 1, 2, 3, 4, 5, 7, 13, 15, 16, and 17. Interesting regions highlighted in this genome screen will be followed up using linkage disequilibrium (LD) methods.

Bipolar Disorder↗
PubMed1996

Prostate-derived soluble factors block osteoblast differentiation in culture.

Bone metastasis is a common event and a major cause of morbidity in prostate cancer patients. After colonization of bone, prostate cells induce an osteoblastic reaction which is not associated with marrow fibrosis (i.e., osteoblast but not fibroblast proliferation). In the present study we test the hypothesis that the tumoral prostatic cell line (PC-3) secretes factors that block the osteoblast differentiation process, resulting in an increase of the relative size of the proliferative cell pool. Our results, using fetal rat calvaria cells in culture, show that conditioned medium from PC-3 cells (PC-3 CM) stimulates osteoblast proliferation and inhibits both alkaline phosphatase (AP) activity (an early differentiation marker) and the mineralization process, measured as calcium accumulation (late differentiation marker). The inhibition of the expression of AP and mineralization depends on the presence of PC-3 CM during the proliferative phase of culture and suggests that both processes occur in a nonsimultaneous fashion. The inhibitory effect of PC-3 CM was not reverted by dexamethasone, which would indicate that prostatic-derived factors and the glucocorticoid do not share a common site of action. Measurement of the proliferative capacity of subcultures from control and treated cells demonstrates that PC-3 CM treatment induces the maintenance of the proliferative potential that characterizes undifferentiated precursor cells.

Alkaline Phosphatase↗
PubMed1996

Ig/myc translocations of the plasmacytoma-prone BALB/c strain occur independently of the genetic and parental origin of the affected chromosomes 6, 12, and 15.

Virtually all murine plasmacytomas (MPCs) carry chromosomal translocations that juxtapose myc on chromosome 15 (chr 15) to one of the three immunoglobulin loci carrying chr 6, 12, or 16. Only some mouse strains are susceptible to MPC induction, however, with BALB/c as the outstanding example. Most other strains are resistant. Our earlier studies with reciprocal BALB/c<-->DBA/2 chimeras suggested that part of this susceptibility is determined at the level of the target cell itself (DBA/2 is MPC resistant). The probability of the Ig/myc translocation is one of the possibly relevant variables. Because MPC resistance is dominant over susceptibility, it is conceivable that the translocations prevail due to some deficiency of the Ig rearrangement or Ig-associated repair mechanisms in BALB/c cells. This could be determined at the level of the chromosomes that participate in the translocation or by genes on other chromosomes. Here, we show that the substitution of the BALB/c-derived chr 12, 6, and 15, which carry IgH, kappa, and myc, respectively, with their homologs derived from MPC-resistant mice, did not affect MPC susceptibility. The use of Robertsonian 4.12 and 6.15 chromosomes in this study has also provided us with the opportunity to assess the parental derivation of the chromosomes participating in the translocation. In contrast to the human chronic myeloid leukemia (CML)-associated BCR/ABL fusion transcript, where a strong bias was claimed that was attributed to imprinting, we have found that the parental chromosomes were randomly involved in the translocation. We have also shown that the translocations could be of uniparental or biparental origin.

Animals↗
PubMed1996

Soluble factors produced by PC-3 prostate cells decrease collagen content and mineralisation rate in fetal rat osteoblasts in culture.

Approximately 70% of patients with prostate cancer develop bone metastases in the advanced state of the disease. In the present study, we sought to test the hypothesis that prostatic cancer cells produce factors that inhibit the mineralisation process in vitro, decreasing the content of type I collagen in rat fetal calvaria osteoblasts. We investigated the capacity of conditioned media (CM) from the human prostatic tumour cell line PC-3 to inhibit the expression of the differentiation programme on osteoblasts in culture, with a primary focus on type I collagen synthesis and degradation. Our results show that PC-3 CM inhibits collagen synthesis and stimulates the production of interstitial collagenase from osteoblasts. A consequential decrease in the content of immunoreactive type I collagen was observed. We have previously demonstrated that PC-3 CM blocks osteoblast differentiation in culture. We propose that under the effect of factors present in PC-3 CM, osteoblastic cells retain the undifferentiated phenotype.

Animals↗
PubMed1996

Genetic mapping using haplotype, association and linkage methods suggests a locus for severe bipolar disorder (BPI) at 18q22-q23.

Manic depressive illness, or bipolar disorder (BP), is characterized by episodes of elevated mood (mania) and depression. We designed a multistage study in the genetically isolated population of the Central Valley of Costa Rica to identify genes that promote susceptibility to severe BP (termed BPI), and screened the genome ot two Costa Rican BPI pedigrees (McInnes et al., submitted). We considered only individuals who fulfilled very stringent diagnostic criteria for BPI to be affected. The strongest evidence for a BPI locus was observed in 18q22-q23. We tested 16 additional markers in this region and seven yielded peak lod scores over 1.0. These suggestive lod scores were obtained over a far greater chromosomal length (about 40 cM) than in any other genome region. This localization is supported by marker haplotypes shared by 23 of 26 BPI affected individuals studied. Additionally, marker allele frequencies over portions of this region are significantly different in the patient sample from those of the general Costa Rican population. Finally, we performed an analysis which made use of both the evidence for linkage and for association in 18q23, and we observed significant lod scores for two markers in this region.

Alleles↗