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Biomedical subjects

P Silva

Publications and source records attributed to P Silva.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Disability in the private pension system in Chile].

BACKGROUND: The degree of disability of workers ascribed to the private allowances system in Chile, is judged by Medical Commissions that apply norms that establish percentages of incapacity, without considering prognosis. AIM: To communicate the causes of disability among Chilean workers ascribed to the private allowances system, their mortality and to correlate the causes of death with diagnoses. SUBJECTS AND METHODS: We analyzed 13,456 consecutive cases judged between August 1990 and April 1992. Mortality was registered up to 12 months after judgment. RESULTS: Total incapacity was determined in 4,158 cases (30.9%), partial incapacity in 1,340 (9.9%) and minor incapacity in 7,958 (59.1%). Osteoarticular diseases were the main cause of disability in 4,460 patients (33.1%) and 77.8% of patients with malignant tumors were considered as having total incapacity. Mortality was 17% among subjects with total incapacity, 1.5% among those with partial disability and 1% among those with minor disability. The cause of death was related to the main disabling disease in 94% of subjects with total incapacity and 66.6% of those with partial incapacity. CONCLUSIONS: Osteoarticular diseases are the main cause of inability among workers ascribed to a private pension system.

Chile↗
PubMed1997

The role of CT following aneurysmal rupture.

Computed tomography is a highly effective method of detecting subarachnoid blood if performed early after aneurysmal rupture, being 95% to 98% positive when lumbar puncture is positive. The localization of the blood defines the location of the aneurysm in approximately 80% of cases. Contrast enhanced computed tomography demonstrates the aneurysm in 75% of cases with the aneurysm is greater than 5 millimeters in size. Computed tomography angiography defines the aneurysm in up to 96% of cases. The amount of subarachnoid blood correlates with the development of vasospasm; cerebral perfusion can be further evaluated with xenon-enhanced computed tomography.

Aneurysm, Ruptured↗
PubMed1997

[Acute myocardial infarct--the hospital phase and follow-up: sex-related differences].

OBJECTIVES: The aim of this study was to evaluate the differences between male and female patients, during hospitalization and follow-up, after acute myocardial infarction. PATIENTS: The clinical data and follow-up files of 504 previously hospitalized patients were studied. The patients were divided in two groups: Group A (male, n = 434) with a mean age of 56.4 +/- 11.7 years, and Group B (female, n = 70) with a mean age of 64.1 +/- 9.2 years. METHODS: The following parameters were studied: vascular risk factors; clinical, functional and anatomic aspects during hospitalization; therapeutic orientation and events; and mortality during follow-up. RESULTS: Hypertension, diabetes, obesity, anterior infarction and lower ejection fraction were more common in Group B. Coronary angiography and thrombolytic therapy were performed more frequently in Group A; severe coronary disease was more common in this group (60.8% vs 38.9%, p < 0.05). During the follow-up we observed a worse prognosis in the Group B, with a higher incidence of events, morbidity and mortality. Therapeutic approach was more aggressive in the male group. CONCLUSION: We observed a worse prognosis in the female patients after myocardial infarction, this fact may be attributed to a later age and higher previous morbidity; the therapeutic and diagnostic procedures are generally less aggressive in females, who are consequently referred for revascularization with more advanced stages of disease, and therefore with higher morbidity and mortality, in the short and long term, even though multivessel coronary disease is more common in males. Thrombolytic therapy was administered and coronary angiography was performed more often in Group A, who had more severe coronary disease.

Aged↗
PubMed1997

[The effects of a cardiac rehabilitation program on 2 populations of coronary patients: acute myocardial infarct and coronary bypass surgery].

UNLABELLED: Cardiac rehabilitation programmes (CRP) have proven beneficial in coronary heart disease. The purpose of this study was to evaluate the effects of our CRP on two coronary heart disease populations: after acute myocardial infarction (AMI-CRP) and after coronary artery bypass surgery (CABG-CRP). Results were compared to control groups (AMI-C and CABG-C). POPULATION: Group AMI-CRP: n = 43 patients, mean age = 48.7 +/- 9.8 years; Group AMI-C: n = 20 patients, mean age = 59.2 +/- 11.5 years; Group CABG-CRP: n = 54 patients, mean age = 54.9 +/- 9.7 years; Group CABG-C: n = 20 patients, mean age = 56.5 +/- 9.9 years. All patients are male and there were no significant differences in ventricular function and coronary disease severity. Parameters were evaluated in the AMI groups at discharge, 3 and 12 months after acute episode; in the CABG groups 3 and 12 months after surgery. RESULTS: Both CRP groups improved their exercise capacity (significantly improved the peak values of METs and double product). A favorable lipid profile change (total cholesterol and HDL) was induced in the CABG-CRP group and more significant in the AMI-CRP group. No significant differences were observed in obesity indexes (body weight and BMI > or = 27.8 Kg/m2). A increase in nonsmokers was important in all groups. Professional reintegration was 91.7% in the AMI-CRP group and 84.4% in the CABG-CRP group. The CRP groups showed a better knowledge of the disease, and a beneficial change in relation to themselves and the world that resulted in a decrease in depression and anxiety. CONCLUSIONS: Participation in our cardiac rehabilitation program, either after AMI or after CABG, improves cardio-respiratory fitness, favorably influences blood lipid profiles, and improves self-reliance and quality of life.

Adult↗
PubMed1996

The lifetime occurrence of sexually transmitted diseases among a cohort aged 21.

AIMS: To determine the lifetime occurrence of sexually transmitted diseases (STDs) among a cohort aged 21. METHODS: Participants were interviewed at aged 21 as part of a multidisciplinary health and development study. Questions on STDs and sexual behaviour were presented by computer. RESULTS: Of the cohort members known to be alive, 92% responded. Among the sexually experienced 8.6% of the men and 17.3% of the women reported ever having had an STD. Genital warts and chlamydial infection were the commonest STDs among the men, and chlamydial infection, genital warts, and genital herpes among the women. General practice was the commonest place for treatment, and only a minority of people were treated at sexual health clinics. The risk of having an STD increased steeply with the lifetime number of sexual partners. CONCLUSIONS: STDs are common problems among young New Zealanders, especially women. The rate was as high as the US. Prevention should be directed at increasing the use of condoms, but education aimed at reducing the number of sexual partners and delaying the onset of sexual involvement should be considered seriously. A more coordinated approach to treatment is required to take into account the diversity of settings where STDs are treated. Surveillance of STDs needs to be extended, as currently the only data are from sexual health clinics.

Adult↗
PubMed1996

Independent and incremental prognostic value of Doppler-derived mitral deceleration time of early filling in both symptomatic and asymptomatic patients with left ventricular dysfunction.

OBJECTIVES: This study sought to investigate the relative and incremental prognostic value of demographic, historical, clinical, echocardiographic and mitral Doppler variables in patients with left ventricular systolic dysfunction. BACKGROUND: The prognostic value of diastolic abnormalities as assessed by mitral Doppler echocardiography has yet to be defined. METHOD: A total of 508 patients with left ventricular ejection fraction < or = 35% were followed up for a mean (+/- SD) period of 29 +/- 11 months. RESULTS: During the follow-up period, 148 patients (29.1%) were admitted to the hospital for congestive heart failure, and 100 patients (19.7%) died. By Cox model analysis, Doppler-derived mitral deceleration time of early filling < or = 125 ms (relative risk [RR] 1.93, 95% confidence interval [CI] 1.4 to 3.7), New York Heart Association functional class III or IV (RR 1.49, 95% CI 1.4 to 2.3), ejection fraction < or = 25% (RR 1.85, 95% CI 1.6 to 2.9), third heart sound (RR 2.06, 95% CI 1.8 to 3.2), age > 60 years (RR 1.95, 95% CI 1.8 to 3.1) and left atrial area > 18 cm2 (RR 1.73, 95% CI 1.6 to 2.7) were all found to be independent and additional predictors of all-cause mortality, and deceleration time was the single best predictor (chi-square 37.80). When all these significant variables were analyzed in hierarchic order, after age, functional class, third sound, ejection fraction and left atrial area, deceleration time still added significant prognostic information (global chi-square from 9.2 to 104.7). Also, deceleration time was the strongest independent predictor of hospital admission for congestive heart failure (RR 4.88, 95% CI 3.7 to 6.9) and cumulative events (congestive heart failure or all-cause mortality, or both; RR 2.44, 95% CI 2.0 to 3.8) in both symptomatic and asymptomatic patients. CONCLUSIONS: Deceleration time of early filling is a powerful independent predictor of poor prognosis in patients with left ventricular systolic dysfunction, whether symptomatic or asymptomatic. A short (< or = 125 ms) deceleration time by mitral Doppler echocardiography adds important prognostic information compared with other clinical, functional and echocardiographic variables.

Cohort Studies↗
PubMed1996

The rectal gland of Squalus acanthias: a model for the transport of chloride.

The rectal gland of the spiny dogfish shark, Squalus acanthias, secretes chloride by a furosemide sensitive process that has been termed "secondary active." Chloride enters the cell across the basolateral cell membrane via the sodium:potassium:2 chloride cotransporter. The energy for this electroneutral uptake step is provided by the electrochemical gradient for sodium directed into the cell. This is maintained by Na-K-ATPase present in the basolateral cell membrane. Present as well in the basolateral cell membrane is a potassium conductance that permits potassium to exit passively. Chloride leaves the cell across the luminal membrane via a chloride conductance closely similar to CFTR. The rectal gland is thus a model for the mechanism of secondary active chloride transport utilized by various epithelial organs throughout the vertebrate kingdom. This report reviews the humoral agents that regulate the secretion of chloride by the rectal gland and the intracellular mechanisms that mediate it. CNP, released from the heart in response to a volume stimulus, causes the release of VIP from nerves within the gland and together with VIP directly activates the rectal gland cell.

Animals↗
PubMed1995

Residual exertional ischemia and unfavorable left ventricular remodeling in patients with systolic dysfunction after anterior myocardial infarction.

OBJECTIVES: This study investigated whether exercise-induced myocardial ischemia influences left ventricular remodeling after anterior myocardial infarction. BACKGROUND: The effects of acute and recurrent ischemia on ventricular function are well established. However, to our knowledge the role of exertional ischemia in the remodeling response after infarction has not been investigated. METHODS: Ninety-one patients with a first anterior Q wave myocardial infarction were studied at 5 weeks by rest echocardiography and exercise scintigraphy. The echocardiographic examination was repeated 6 months later. On the basis of the presence and extent of reversible perfusion defects on exercise scintigraphy, patients were assigned to groups with no exertional ischemia (group 1, n = 20 [22%], mild to moderate ischemia (group 2, n = 45 [49%]) and severe exertional ischemia (group 3, n = 26 [29%]). RESULTS: Initial left ventricular volumes were similar, and no differences were found among the three groups in the remodeling response over the 6-month period of the study. However, patients in groups 2 and 3 with an ejection fraction < or = 40% showed significant (p < 0.01) ventricular enlargement over time, which was similar between the two groups (end-diastolic volume [mean +/- SD] from 74 +/- 13 to 80 +/- 17 ml/m2 in group 2 and from 72 +/- 11 to 81 +/- 19 ml/m2 in group 3; regional dilation from 42 +/- 16% to 52 +/- 22% in group 2 and from 38 +/- 18% to 46 +/- 27% in group 3). In contrast, ventricular dimensions did not change in group 1 patients with an ejection fraction < or = 40% as well as in patients in all three groups with an ejection fraction > 40%. CONCLUSIONS: Exercise-induced myocardial ischemia may contribute to progressive ventricular enlargement in patients with poor left ventricular function after a large anterior myocardial infarction.

Analysis of Variance↗
PubMed1995

Obsessive-compulsive disorder in a birth cohort of 18-year-olds: prevalence and predictors.

OBJECTIVE: To report descriptive epidemiological information on obsessive-compulsive disorder (OCD) in an unselected birth cohort of 930 males and females, aged 18 years. METHOD: An epidermiological study of the prevalence of self-reported OCD at age 18, and a longitudinal analysis of the prospective predictors of OCD. RESULTS: Using the Diagnostic Interview Schedule, the authors found a 1-year prevalence rate of 4%, with a male-female ratio of 0.7:1. The majority of OCD cases met criteria for a comorbid disorder, most commonly depression (62%), social phobia (38%), and substance dependence (alcohol 24%, marijuana 19%). CONCLUSIONS: Data collected on the sample from birth to age 18 years indicated that many childhood risk factors theorized in the literature did not predict OCD in this sample. However, a history of depression and substance use were prospective risk factors for OCD.

Adolescent↗
PubMed1995

Adrenal changes in murine pulmonary tuberculosis; a clue to pathogenesis?

When mice were infected with virulent Mycobacterium tuberculosis H37Rv by the intra-tracheal route, there was an early phase of adrenal hyperplasia, histologically resembling the adrenocorticotropic (ACTH)-driven changes seen in Cushing's disease. This was followed at 3 weeks by progressive atrophy until the weight of the adrenals was approximately 50% of that seen in control uninfected mice, in spite of the fact that the adrenals were not infected. All layers of the adrenal cortex were affected, but the medulla was normal. Electron microscope studies revealed apoptosis. The switch from adrenal hyperplasia to adrenal atrophy corresponded to onset of an IgG1 response recognising a wide range of mycobacterial components in Western blots. Delayed type hypersensitivity (DTH) responses were seen throughout, but differed in their sensitivity to TNF alpha. Thus if TNF alpha was injected at 24 h into DTH sites elicited during the phase of adrenal hyperplasia, there was no increment in swelling at 48 h. However similar injections of TNF alpha resulted in a doubling of the swelling in DTH sites elicited during the phase of adrenal atrophy. This may be relevant to the pathogenesis of cytokine-mediated tissue damage in the human disease. If 2 months before mice received the intratracheal infection, they were pre-immunised with 1 x 1097) autoclaved Mycobacterium vaccae, a stimulus previously shown to induce a Th1 pattern of response, the early increase in adrenal weight was attenuated and delayed, and the subsequent atrophy did not occur. In sharp contrast, pre-immunisation with 1 x 10(9) autoclaved M. vaccae, known to prime a mixed pattern of cytokine release (IFN gamma and IL-4), resulted in adrenal atrophy that began within 4 days of infection, and was complete by day 14. These results suggested that the pattern of cytokine release provoked by the infection, modulated the adrenal changes, perhaps in synergy with products derived from the organisms themselves. Since we have already shown that profound adrenal changes also occur in human tuberculosis, we now propose that a change somewhere in the cytokine-hypothalamo-pituitary-adrenal axis may underlie the T cell dysfunction and immunologically-mediated tissue damage in this disease.

Adrenal Glands↗
PubMed1994

Effects of saline, mannitol, and furosemide on acute decreases in renal function induced by radiocontrast agents.

BACKGROUND: Injections of radiocontrast agents are a frequent cause of acute decreases in renal function, occurring most often in patients with chronic renal insufficiency and diabetes mellitus. METHODS: We prospectively studied 78 patients with chronic renal insufficiency (mean [+/- SD] serum creatinine concentration, 2.1 +/- 0.6 mg per deciliter [186 +/- 53 mumol per liter]) who underwent cardiac angiography. The patients were randomly assigned to receive 0.45 percent saline alone for 12 hours before and 12 hours after angiography, saline plus mannitol, or saline plus furosemide. The mannitol and furosemide were given just before angiography. Serum creatinine was measured before and for 48 hours after angiography, and urine was collected for 24 hours after angiography. An acute radiocontrast-induced decrease in renal function was defined as an increase in the base-line serum creatinine concentration of at least 0.5 mg per deciliter (44 mumol per liter) within 48 hours after the injection of radiocontrast agents. RESULTS: Twenty of the 78 patients (26 percent) had an increase in the serum creatinine concentration of at least 0.5 mg per deciliter after angiography. Among the 28 patients in the saline group, 3 (11 percent) had such an increase in serum creatinine, as compared with 7 of 25 in the mannitol group (28 percent) and 10 of 25 in the furosemide group (40 percent) (P = 0.05). The mean increase in serum creatinine 48 hours after angiography was significantly greater in the furosemide group (P = 0.01) than in the saline group. CONCLUSIONS: In patients with chronic renal insufficiency who are undergoing cardiac angiography, hydration with 0.45 percent saline provides better protection against acute decreases in renal function induced by radiocontrast agents than does hydration with 0.45 percent saline plus mannitol or furosemide.

Aged↗
PubMed1993

Prognostic significance of early ischemia after acute myocardial infarction in low-risk patients. IRES (Ischemia Residua) Study Group.

Early postinfarction angina is generally believed to imply an unfavorable prognosis. However, most of the published information devices from data collected in the prethrombolytic era, with widely differing populations and definitions of early angina, and very little data pertinent to low-risk patients are available. This collaborative study prospectively assessed the incidence of early recurrent ischemia after thrombolysis, as well as its prognostic significance, in 453 consecutive patients aged < or = 70 years with an uncomplicated course in the first 24 hours of a first myocardial infarction participating in the second Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI-2) trial. Early recurrent ischemia (spontaneous, transient ST depression or elevation of > 1 mm and/or T-wave inversion), assessed in the coronary care unit with continuous clinical and electrocardiographic monitoring, was documented in 35 of 453 patients (8%) and was unrelated to sex, age, electrocardiographic location, Q-wave or non-Q-wave infarction, thrombolytic agent and time to its administration. In-hospital cardiac events (7 deaths, 19 nonfatal reinfarctions and 8 urgent revascularizations) occurred in 15 of 35 patients (43%) with versus 19 of 418 without (4.5%) recurrent ischemia (p < 0.001). At the 6-month follow-up of 352 medically treated patients who did not have in-hospital events, the incidence of death, reinfarction and recurrent angina was comparable between patients with (2 of 18, 11%) and without (62 of 334, 19%) early ischemia (p = NS). With use of stepwise multivariate analysis, early ischemia was the only significant predictor of in-hospital cardiac events (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

The importance of conduct problems and depressive symptoms in predicting adolescent substance use.

The current study assessed the relative importance of conduct problems and depressive symptoms, measured at two ages (11 and 15), for predicting substance use at age 15 in an unselected birth cohort of New Zealand adolescents. Among males, when the relative predictive utility of both conduct problems and depressive symptoms was assessed, only pre-adolescent depressive symptoms were found to predict multiple drug use 4 years later. No predictive relation was found between early symptomatology and later substance use among females. The strongest association between predictors and substance use emerged between age 15 multiple drug use and concurrent conduct problems for both males and females. Finally, both conduct problems and depressive symptoms at age 15 were also found to be associated with concurrent "self-medication" among females.

Adolescent↗
PubMed1993

Secretion of nitrate by rectal gland of Squalus acanthias.

1. Rectal glands secrete nitrate at 30% of their capacity to secrete chloride. 2. Nitrate secretion is directly related to its concentration at constant chloride concentrations. 3. Chloride has a biphasic effect on nitrate secretion. 4. Hill coefficients at chloride < 100 mM are equal to 1, while at 100 mM indicate inhibition of nitrate by chloride. 6. Lineweaver-Burk plots at chloride < 100 indicate a single site, while at 100 mM indicate inhibition of nitrate by chloride. 7. Bumetanide inhibits nitrate secretion. 8. The data suggest that nitrate interacts with one of the two chloride sites of the chloride transporter.

Animals↗
PubMed1993

Neuropeptide Y inhibits chloride secretion in the shark rectal gland.

We studied the effects of the 36-amino acid peptide, neuropeptide Y (NPY), on salt secretion by the rectal gland of Squalus acanthias. We used three preparations: whole isolated perfused glands, freshly prepared separated rectal gland tubules, and confluent monolayers of cultured rectal gland cells. In perfused glands NPY inhibited secretion stimulated by vasoactive intestinal peptide (VIP), forskolin, or adenosine 3',5'-cyclic monophosphate (cAMP) and theophylline. Maximal inhibition of 63 +/- 3.4% was seen at 3 x 10(-8) M NPY, with half-maximal effect at 3 x 10(-9) M. NPY did not inhibit the basal activity of rectal gland adenylate cyclase or that stimulated by VIP. The inhibitory action of NPY was not prevented by procaine, nifedipine, or diltiazem, suggesting that it was not secondary to the release of somatostatin or other unknown neurotransmitters from rectal gland nerves. In confirmation, somatostatin was not detected in the venous effluent after administration of NPY. NPY also inhibited transport-related oxygen consumption in separated rectal gland tubules and inhibited short-circuit current generated by confluent monolayers of primary cultures of rectal gland cells. The results indicate that NPY inhibits chloride secretion by a direct action on cells of the shark rectal gland at a site distal to the generation of cAMP.

Adenylyl Cyclases↗
PubMed1993

C-type natriuretic peptide receptors and signaling in rectal gland of Squalus acanthias.

Recent evidence suggests that the newly described natriuretic peptide, C-type natriuretic peptide (CNP), may be the circulating form of natriuretic peptide in the shark. In the shark CNP has a major site of action in the rectal gland, which augments chloride secretion in response to stimulation by volume loading or CNP infusion. We therefore examined the shark rectal gland for natriuretic peptide receptors and determined the presence of guanylate cyclase-linked receptors and non-guanylate cyclase-linked receptors for CNP in this tissue. CNP binds with uniform high affinity (dissociation constant of 78 +/- 11 pM) to receptors of high density (receptor density of 61 +/- 0.7 fmol/mg protein) in plasma membranes prepared from the rectal gland. By use of rat atrial natriuretic peptide (rANP) as a competing ligand, two classes of receptors become apparent in this population, both of which have similar affinity for CNP, but different affinities for rANP. The low-molecular-weight natriuretic peptide receptor-specific peptide, des-[Gln116,Ser117,Gly118, Leu119,Gly120]rANP-(102-121), binds to 50% of the receptors in the rectal gland, but fails to bind to the remaining 50% even at micromolar concentrations. Porcine brain natriuretic peptide (pBNP) binds with uniformly diminished affinity to all receptors, whereas the unrelated peptide, porcine vasoactive intestinal peptide, does not bind these receptors. The importance of the integrity of the ring structure of CNP is underlined by the significant loss of affinity when the peptide ring is opened.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗