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Biomedical subjects

M C Gomes

Publications and source records attributed to M C Gomes.

At least 19 recordsLinked to original sources
PubMed2004

Recurrent epidemics in small world networks.

The effect of spatial correlations on the spread of infectious diseases was investigated using a stochastic susceptible-infective-recovered (SIR) model on complex networks. It was found that in addition to the reduction of the effective transmission rate, through the screening of infectives, spatial correlations have another major effect through the enhancement of stochastic fluctuations, which may become considerably larger than in the homogeneously mixed stochastic model. As a consequence, in finite spatially structured populations significant differences from the solutions of deterministic models are to be expected, since sizes even larger than those found for homogeneously mixed stochastic models are required for the effects of fluctuations to be negligible. Furthermore, time series of the (unforced) model provide patterns of recurrent epidemics with slightly irregular periods and realistic amplitudes, suggesting that stochastic models together with complex networks of contacts may be sufficient to describe the long-term dynamics of some diseases. The spatial effects were analysed quantitatively by modelling measles and pertussis, using a susceptible-exposed-infective-recovered (SEIR) model. Both the period and the spatial coherence of the epidemic peaks of pertussis are well described by the unforced model for realistic values of the parameters.

Disease Outbreaks↗
PubMed2000

Rare complication of an arteriovenous fistula for dialysis: glaucoma.

We present a rare complication of an arteriovenous fistula for haemodialysis. Incompetence of the anti-reflux mechanism associated with elevated venous pressure in the subclavian vein provided conditions for intense blood reflux to the left jugular territory and development of ipsilateral glaucoma, successfully treated by ligation of the left jugular veins.

Aged↗
PubMed2000

Multiple dose vaccination against childhood diseases: high coverage with the first dose remains crucial for eradication.

The high vaccination coverage required to eradicate communicable diseases like measles, mumps and rubella, with a single dose of vaccine, has prompted many countries to introduce a second dose. In this paper we investigate the conditions to eradicate childhood diseases with multiple doses of vaccine by obtaining explicit analytical solutions to the classical compartment model that assumes an age-independent force of infection and conceptualizes the host population as divided into maternally protected (P), susceptibles (S), latents (E), infectious (I), and removed (R). The solutions allow a quantitative discussion of the long-term impact of vaccination schedules with an arbitrary number of doses of vaccine. It becomes possible to determine the effect of the number of doses, ages at vaccination, and coverage rates of vaccines against childhood diseases. In an example with a two-dose vaccination schedule against measles, we show that, in spite of a second dose, a high (> 90%) immunization coverage in the first dose is still crucial to achieve eradication. With a high first-dose coverage, however, eradication is relatively insensitive to the age of the second dose and requires only moderate coverage rates in the latter.

Child↗
PubMed1999

Diphtheria, pertussis, and measles in Portugal before and after mass vaccination: a time series analysis.

Techniques of time series analysis were used to examine historical records of the incidence of diphtheria, pertussis, and measles, and of deaths by measles in Portugal during the twentieth century. There are statistically significant seasonal and longterm oscillations in the incidence of these diseases. Seasonal oscillations appear to be in close association with the resumption of school classes in the fall in the case of diphtheria, but not in pertussis and measles. Long-term oscillations in pertussis (3.5-4 year period) and measles (3-year period), before vaccination, corroborate theoretical predictions about the dynamics of these diseases, whereas absence of long-term oscillations in diphtheria is probably due to the influential presence of carriers upon the dynamics of the disease. Mass vaccination strongly suppressed disease incidence, did not eliminate seasonal oscillations, and appeared to have acted to lengthen long-term periodicity in pertussis and measles.

Adolescent↗
PubMed1998

[Long-term follow-up of anatomic heart transplantation. Apropos of 60 patients with a mean follow-up of 36 months].

The aim of this study was to collect different problems seen in long-term evolution of patients who had anatomical cardiac transplantation and to compare with those seen in patients with standard transplantation. During the mean follow-up of 36 months, we analysed different data of 60 patients mean aged 51, who underwent anatomical cardiac transplantation. Six patients (10%) died within the 30 days after surgery. No patient needed the use of permanent pacemaker. Echocardiographic examination found normal atrial shape. One month after surgery, echocardiography described 16 tricuspid regurgitations (22.66%) and 8 mitral regurgitations (13.33%), 1 year later, there was respectively 13.33 and 6.66% tricuspid and mitral regurgitation. We had 8 late deaths: 1 sudden death, 2 chronic rejections, 1 pancreatitis and 4 cancers. The survival analysis pointed out 84% at 1 year, 80 at 2 years, 78 at 3 years and 73 at 5 years. Six months after surgery, 80% of patients were treated for high blood pressure; 85% had serum creatinine level equal or superior to 13 mg/L, with mean serum ciclosporin at 130 ng/mL. At the 3rd month, 6 endomyocardial biopsies were equal or superior to grade 2 rejection (International Society for Heart Transplantation). Between the 3rd and 12th month, 3 endomyocardial biopsies were equal or superior to grade 2 rejection, and the same between the 12th and 24th month. The infections rate was 0.8 episode per patient. Long term follow-up of anatomical cardiac transplantation faces the same problems as in standard cardiac transplantation. It is better to perform anatomical cardiac transplantation because of its early postsurgical advantages. Long term care is the same as in standard cardiac transplantation.

Actuarial Analysis↗
PubMed1996

Lisinopril and diltiazem reduce left ventricular mass without changing blood pressure in normotensive subjects with exaggerated blood pressure response to exercise.

OBJECTIVE: To determine whether high left ventricular mass may be reduced by antihypertensive drugs in normotensives with exaggerated blood pressure response to exercise as it occurs in hypertensive patients. DESIGN AND METHODS: Randomized, single blind, controlled parallel study evaluating the influence of placebo; lisinopril 20 mg/day, diltiazem 180 mg/d for 5-6 months on left ventricular mass (LVM), evaluated by echo and on "casual" and 24-h ambulatory blood pressure (24-h BP) in normotensive subjects with exaggerated blood pressure response to exercise (Group I) and in weight--and age--matched mild-moderated hypertensive patients (Group II), all with high left ventricular mass. PATIENTS: Placebo, lisinopril and diltiazem, were administered for 5-6 months in respectively 8+9+9 subjects of Group I and 8+9+10 patients in Group II. RESULTS: Placebo did not change either LVM index or 24-h BP values in Group I and Group II. Diltiazem and lisinopril reduced LVM index in both Groups I and II but 24-h BP values were only reduced in Group II. Lisinopril appeared to be more potent than diltiazem on LVM regression. Slopes of LVM index regression were not different between Groups I and II for each drug. Drug-induced changes of LVM index did not correlate with blood pressure changes. CONCLUSIONS: Drug-induced regression of LVM may be achieved in man (Group I) without any reduction of blood pressure. This may be explained by interference with growth-promoting systems other than with cardiac unloading. Also, the similar pattern of LVM regression that was observed in both Groups I and II suggests that similar underlying mechanisms may be involved in the LVH regression in these two populations.

Adult↗
PubMed1996

[Epidemiologic features of congestive heart failure. Retrospective analysis of 2561 hospitalizations].

OBJECTIVES: The aim of this study was to characterise the epidemiology of congestive heart failure namely assessing demographic, etiologic and prognostic aspects, and the hospital admission trends in the last 6 years. METHODS: Retrospective analysis of computerised data concerning patients with congestive heart failure admitted to the department of Internal Medicine. LOCATION: A central hospital in the North of Portugal. SUBJECTS: Two thousand five hundred and sixty-one patients older than 10 years, admitted to the Internal Medicine Department of a central hospital in the North of Portugal between January 1, 1989 and December 31, 1994 and discharged with the principal or first listed diagnosis of congestive heart failure (ICD-9-CM code 4280). RESULTS: Eighty per cent of the patients had more than 60 years of age and the mean age was 69 years (female: 70.40 +/- 12.65; male: 66.24 +/- 12.25; p < 0.0001). Fifty-four per cent were females and 46 per cent males. The prevalence of congestive heart failure in the Internal Medicine Department was 4.8%. Between the ages of 15 and 44 years the hospital age-specific prevalence was between 16.1/10,000/year and 26.7/10,000/year for women and between 14.5/10,000/year and 16.1/10,000/year for men. For ages equal or greater than 75 years it was between 508.9/10,000/year and 561.3/10,000/year for women and between 300.2/10,000/year and 421.8/10,000/year for men. Possible causes of congestive heart failure were: valve disease in 26 per cent of patients, coronary artery disease in 24 per cent and hypertension in 20 per cent. The average case-fatality rate was 15.15% (female: 15.54%; male: 14.69%; chi 2 = 0.36; p > 0.55) evolving from 19.45% in 1989 to 12.59% in 1994 (chi 2 = 6.85; p < 0.01). Between the ages of 15 and 44 years the hospital cause-specific mortality rate was 16.2/100,000 and for ages equal or greater than 75 years it was 743.6/100,000. Stepwise logistic regression produced the following odds ratios for the variables significantly associated with dead during hospital admission: age (> or = 70 years)--1.48; infectious diseases--1.37; central nervous system diseases--2.28; chronic renal diseases--1.96; cardiac arrest--24.1; pulmonary embolism--2.26; acute renal failure--7.93; clinical signs of severe sodium and water retention--1.49; hyponatremia--3.39; other electrolyte abnormalities and acid-base balance disturbances--1.78. The simple linear regression of daily admissions on time produced a positive slope of 0.0002 (p < 0.002). CONCLUSIONS: The hospital prevalence of congestive heart failure is identical to other Western countries and is greater among the elderly patients. Valve disease, coronary artery disease and hypertension are the most frequent causes of congestive heart failure. An increasing trend in hospital admissions for congestive heart failure was observed. The hospital mortality was reduced in the last 6 years and was greater among the elderly patients. Age (> or = 70 years), the presence of comorbidity (infectious disease, central nervous system disease, acute renal failure, chronic renal disease and pulmonary embolism), hyponatremia, other electrolyte abnormalities and acid-base balance disturbances, resuscitated cardiac arrest and the presence of severe sodium and water retention have prognostic significance.

Aged↗
PubMed1996

[Pharmacologic treatment of acute myocardial infarction: 2 large clinical trials at a central hospital].

OBJECTIVES: To analyse the clinical practice concerning the pharmacological therapy of acute myocardial infarction (AMI), comparing it with the guidelines for the management of AMI and exploring the reasons for its under use or over use. METHODS: Retrospective analysis of clinical records of patients with the discharge diagnosis of AMI. LOCATION: A central hospital in the North of Portugal. SUBJECTS: One hundred and ninety-one patients admitted to the Internal Medicine Department of a central hospital in the North of Portugal between January 1, 1993, and December 31, 1994. RESULTS: Thrombolytic therapy was performed in 24.1% of the patients. At discharge 32.6% of the patients were on therapy with beta blockers, 68% with angiotensin converting enzyme inhibitors (ACEI) and 88.4% with aspirin. Stepwise logistic regression produced the following odds ratios for the variables significantly associated with: a) thrombolytic therapy: hypertension - 0.38; non-Q wave infarction - 0.17; time between onset of symptoms and hospital admission greater than 6 hours - 0.18; admission to coronary unit - 14.72; b) beta blocker therapy: age > 60 years - 0.23; serum LDH > 1000 U/L - 0.41; diastolic blood pressure > 85 mmHg - 3.73; Killip > 1 - 0.08; concomitant therapy with calcium antagonist - 0.33; previous therapy with beta blocker - 14.87; hospital stay greater than 10 days - 2.67; c) ACEI therapy: anterior wall infarction - 3.07; non Q wave infarction - 0.13; congestive heart failure - 9.36; serum creatinine > or = 15 mg/dl - 0.03. CONCLUSIONS: Beta blockers and thrombolytic are under used and ACEI overused. The delay in hospital admission is the most important factor opposing the use of thrombolytic therapy, imposing the need for measures that ean reduce this delay. Therapy with beta blockers (highly cost-effective) can be increased by educational intervention among the physicians. The overuse of ACEI can be ascribed to the good results of randomised trials.

Adrenergic beta-Antagonists↗
PubMed1993

[Malignant vasovagal syncope: a case of prolonged asystole induced by the "tilt" test and aggravated by therapy with a beta blocker (a clinical case and diagnostic, physiopathologic and therapeutic review)].

The authors describe a case of a middle-age male with recurrent syncope, in whom the tilt test was useful in the diagnosis and therapeutic evaluation. Malignant criteria of vasovagal syncope were established and the beta blocking worsening effect was documented, in spite of the general agreement of the first choice drug.

Adult↗
PubMed1992

[The SAVE trial: rational basis, results, and reflections].

Recent concepts about post-infarction left ventricular remodeling, which is the basis for heart failure in these patients, as well as its prevention by ACE inhibitors are briefly summarized. Those data were the rationale for the SAVE trial. The most important initial aspects of this trial (general objective, pre-specified endpoints, inclusion and exclusion criteria, etc.) are then described as well as the basal characteristics of the respective cohort. The most important results of the SAVE trial, now in press, are subsequently presented. Several clinical guidelines, derived from these results, are then suggested. Finally, some new questions, both clinical and pathophysiological, and originated by the results from the SAVE results, are commented.

Adult↗
PubMed1991

[Study of the autonomous nervous system with heart rate spectral analysis in acute myocardial infarction].

OBJECTIVES: Characterize power spectrum pattern of heart rate variability (HRV) and assessment of relative cardiac nervous system in patients with acute myocardial interaction of sympathetic and parasympathetic infarction. We also compared the spectral power with some known prognostic risk variables. STUDY DESIGN: Study of patients with acute myocardial infarction (AMI) and sedentary healthy subjects sex matched. SUBJECT AND METHODS: 19 postinfarction patients aged 55.7 +/- 10.5 years and 19 healthy subjects controls aged 53.9 +/- 11.0. ECG signals were recorded after 15 minutes of supine rest with controlled breathing at 15 cycles/min. Signal acquisition was done at 300 samples/sec. From 512 consecutive sinus beats, we calculated the average, standard deviation, maximum and minimum values and rate between the longest and shortest R-R interval (E/I). We also calculated, after computing the fast Fourier transform, the total spectrum power, low frequency component (LF, from 0.01 to 0.15 Hz), high frequency component (HF, from 0.15 to 0.50 Hz) and its ratio (LF/HF). Thereafter, we correlated these results with radionuclide ejection fraction, duration of treadmill test, Holter ventricular premature complex and localization of infarction. RESULTS: The average R-R interval was 757.9 +/- 116.3 and 850.9 +/- 133.9 msec (p less than 0.05), the R-R corrected standard deviation was 15.3 +/- 6.0 and 38.2 +/- 8.5 msec (p less than 0.001) and ratio E/I was 1.13 +/- 0.06 and 1.32 +/- 0.09 (p less than 0.001) in AMI and control group, respectively. In AMI group, low frequency spectral band was very decreased (LF = 0.03 +/- 0.02 sec2) and high frequency was virtually absent (HF = 0.01 +/- 0.01 sec2) compared with control group (LF = 0.13 +/- 0.06 and HF = 0.14 +/- 0.15 sec2), p less than 0.001; ratio LF/HF was increased in AMI group. There were no significant differences between groups for normalized LF (LF%) and HF (HF%). CONCLUSIONS: These results showed that spectral pattern in AMI patients had very low LF and HF power density. Decreased HRV in that group was mainly due to diminished parasympathetic influence in cardiac regulation; nevertheless ratio LF/HF was increased which represents an imbalance of sympatho-vagal activity with predominance of sympathetic tone. We found poor correlation between frequency domain indices and other risk variable; best correlation was between total spectral power and radionuclide ejection fraction (r = 0.642, p less than 0.01), which could express independent prognostic value in AMI patients risk stratification.

Autonomic Nervous System↗
PubMed1991

Evaluation of left ventricular function after acute myocardial infarction. Two-dimensional echocardiography versus radionuclide angiography. Study of 50 patients.

Two-dimensional echocardiography and gated blood radionuclide angiography was performed in 50 patients (mean age 51.3 years; 48 men and 2 women) after acute myocardial infarction, before discharge from the hospital. The aim of this study was to compare the wall motion score, determined by two-dimensional echocardiography (2DE), with the ejection fraction obtained by radionuclide angiography (RNA). The correlation between the results obtained by 2DE and RNA was good (r = 0.75; p less than 0.0001). We conclude that 2DE is a powerful diagnostic tool for the evaluation of left ventricular function.

Adult↗
PubMed1984

Effect of levamisole on experimental paracoccidioidomycosis in the Syrian hamster: immunologic and histopathologic correlation.

The effect of levamisole (LMS) was studied in hamsters inoculated with live yeast phase culture of Paracoccidioides brasiliensis by intratesticular route. One group started LMS therapy at an early stage of infection (LMS3 group), when the animals were immunocompetent, and another group was treated in a later stage, when the immune response was already depressed (LMS12 group). As control, one group was not treated. The alterations induced by levamisole were studied by immunologic and histopathologic parameters. Compared to controls, the LMS3 group presented normal levels of cellular immune response and inflammatory reaction characterized by compact epithelioid granuloma during a longer period of time. In addition, this group showed a lower incidence of amyloidosis and lower fungi proliferation in the lesions. In the LMS12 group a transient enhancement was noteworthy of cellular immune response with maintenance of the compact pattern of the epithelioid granuloma as in the LMS3 group; however, the number of fungi and incidence of amyloidosis were similar to controls. The differences between both treated groups may be accounted for by some factors such as host immune competence, timing and total dose of LMS administered. Levamisole may be of value as additional therapy in paracoccidioidomycosis.

Amyloidosis↗