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Biomedical subjects

L Araujo

Publications and source records attributed to L Araujo.

At least 37 records · Page 2Linked to original sources
PubMed1990

A community detection program for abdominal aortic aneurysm.

This study aimed to discover the prevalence of undiagnosed abdominal aortic aneurysm in the community in men aged sixty-five to seventy-four. All 1,392 men in this age group registered with twenty general medical practitioners were invited for free health screening at hospital and 746 attended. The abdominal aorta was imaged by ultrasound and its anteroposterior diameter measured. An abdominal aortic aneurysm was present in 6.3% and the aneurysm was 4.0 cm or more in diameter in 2%.

Aged↗
PubMed1989

Sustained nonoxidative glucose utilization and depletion of glycogen in reperfused canine myocardium.

Ischemically injured reperfused myocardium is characterized by increased 18F-fluorodeoxyglucose uptake as demonstrated by positron emission tomography. To elucidate the metabolic fate of exogenous glucose entering reperfused myocardium, D-[6-14C] glucose and L-[U-13C] lactate were used to determine glucose uptake, glucose oxidation and the contribution of exogenous glucose to lactate production. The pathologic model under investigation consisted of a 3 h balloon occlusion of the left anterior descending coronary artery followed by 24 h of reperfusion in canine myocardium. The extent and severity of myocardial injury after the ischemia and reperfusion were assessed by histochemical evaluation (triphenyltetrazolium chloride and periodic acid-Schiff stains). Thirteen intervention and four control dogs were studied. The glucose uptake in the occluded/reperfused area was significantly enhanced compared with that in control dogs (0.40 +/- 0.14 versus 0.15 +/- 0.10 mumol/ml, respectively). In addition, a significantly greater portion of the glucose extracted immediately entered glycolysis in the intervention group (75%) than in the control dogs (33%). The activity of the nonoxidative glycolytic pathway was markedly increased in the ischemically injured reperfused area, as evidenced by the four times greater lactate release in this area compared with the control value. The dual carbon-labeled isotopes showed that 57% of the exogenous glucose entering glycolysis was being converted to lactate. Exogenous glucose contributed to greater than 90% of the observed lactate production. This finding was confirmed by the histochemical finding of sustained glycogen depletion in the occlusion/reperfusion area. The average area of glycogen depletion (37%) significantly exceeded the average area of necrosis (17%). These data demonstrate enhanced and sustained activity of the nonoxidative glycolytic pathway after a prolonged occlusion with reperfusion in canine myocardium. Because glycogen stores remain depleted, exogenous glucose becomes an important myocardial substrate under these pathologic conditions.

Animals↗
PubMed1989

How fast do very small abdominal aortic aneurysms grow?

Fifty patients with abdominal aortic aneurysms from 2.5 to 5.0 cm in anteroposterior diameter (median 3.1 cm, mean +/- S.E. 3.3 +/- 0.1 cm) were initially offered non-operative treatment. Two patients have subsequently undergone successful elective aneurysm resection because of increase in aneurysm size, and a third has died. The median annual growth rate of the aneurysm has been 0.22 cm and 77.8% increased in size between 6 monthly ultrasound examination. For aneurysms less than 4.0 cm the maximum 6 monthly increment in diameter was 0.7 cm. Even the smallest abdominal aortic aneurysms usually progressively increase in size and 6 monthly ultrasound remeasurement of aneurysm diameter is an essential component of non-operative management.

Aged↗
PubMed1989

Rabbit myocardial 82Rb kinetics and a compartmental model for blood flow estimation.

Quantification of regional myocardial blood flow (MBF) with rubidium-82 (82Rb) and positron emission tomography (PET) requires the validation of a tracer kinetic model that adequately describes the kinetics of 82Rb in tissue. We performed 134 82Rb kinetic experiments in 24 isolated, arterially perfused rabbit interventricular septa at different flow rates (0.5-4.5 ml.min-1.g-1) and under the following conditions: varied concentrations of glucose (2.8-11 mM), insulin (0-5 mU/ml), and potassium (5-8 mM); varied pH (7.2-7.8); varied workload; and the addition of acetylstrophanthidin (1.0 microM). The measured 82Rb tissue time-activity curves consisted of two exponential components, with half times inversely related to MBF. The size of the slow component decreased as MBF increased (from 70% at 0.3 ml.min-1.g-1 to 30% at 2.0 ml. min-1.g-1). The kinetics were not strongly dependent on the conditions studied and were consistent with a compartmental model containing two communicating compartments. The volume of the fast exchangeable compartment and the transport rate constant from the fast to the slow compartment were found to be independent of MBF. Values of MBF were estimated with the compartmental model from 82Rb kinetics, and they correlated well with the directly measured MBF (r = 0.91; slope = 1.03).

Animals↗
PubMed1988

Oxford screening programme for abdominal aortic aneurysm in men aged 65 to 74 years.

824 men aged 65 to 74 were invited for ultrasound screening of the aorta and 426 (51.7%) attended. An abdominal aortic aneurysm was discovered in 23 (5.4%), and in 10 (2.3%) the aneurysm was 4.0 cm or more in diameter. 2 other patients had a common iliac artery aneurysm. The 36 men who had objective evidence of occlusive arterial disease of the lower limbs were twice as likely to be tobacco smokers and accounted for 5 (20%) of the aneurysms discovered. Extension of this screening programme to England and Wales could be expected to identify 52,500 men with an abdominal aortic aneurysm. If elective surgical replacement of the aneurysm were to be accepted by 60% of those with aneurysms 4 cm or more in diameter, 6000 unnecessary deaths from aortic aneurysm rupture could be prevented.

Aged↗
PubMed1988

A community screening programme for abdominal aortic aneurysms.

Three-hundred and sixty-nine unselected men aged 65-79 years were invited for screening for abdominal aortic aneurysm. One hundred and forty-one men were examined and 4 aneurysms detected. 43.2% of men aged 65-74 attended for examination in response to a single unsolicited letter of explanation with the date of an appointment, but only 29.1% of those aged 75-79 years. It is suggested that community mortality from ruptured aortic aneurysm could be reduced by ultrasound screening of the aorta in men aged 65-74 years and early selective aneurysm surgery.

Aged↗
PubMed1988

Validation of PET-acquired input functions for cardiac studies.

To validate the determination of the arterial input function by noninvasive dynamic PET imaging, measurements of blood-pool activity in canine LV by PET were compared to beta probe measurements of arterial blood withdrawn directly from the LV. PET scans were done during intravenous bolus injections of [13N]ammonia or 82Rb, while the activity of blood withdrawn continuously from a catheter inserted in the LV was measured with a beta probe. PET determinations of LV blood-pool activity were compared with dispersion-corrected beta probe time-activity curves. In 15 experiments involving four dogs under a wide range of physiologic conditions, LV time-activity curves obtained with PET matched well in shape with those obtained with the beta probe. Linear regression yielded slopes within 10% of unity (95% confidence interval) and high correlation (r greater than 0.968, p less than 0.001). We conclude that noninvasive measurement of the arterial input function by dynamic PET imaging is valid.

Ammonia↗
PubMed1987

Antibodies to a surface membrane marker from human mammary carcinoma cell line.

A tumor surface antigen (BTA-BT20-68K) was isolated from a human mammary carcinoma cell line (BT-20). The antigen (Mr 68,000) induced the formation of high titer antibodies which recognized BTA-BT20-68K as a cell surface marker by the immune adherence hemagglutination test and recognized the soluble antigen by solid phase radioimmunoassay. The antibodies which failed to recognize human beta-2-microglobulin, alpha-fetoprotein, and carcinoembryonic antigen were cytotoxic to the parent BT-20 tumor cells at high serum dilutions. The antibodies recognized a similar tumor surface marker isolated directly from human breast adenocarcinomas, but failed to recognize human lymphocyte antigens isolated from BT-20 cells or bound to human lymphocytes bearing human lymphocyte antigen markers in common with those of BT-20 cells. Added to BT-20 tumor cells in culture and in the absence of complement, antibody-dose-related inhibition of tumor cell growth was documented. In the presence of complement, the antibodies were highly cytotoxic to the parent cells. These results demonstrate the presence of a unique tumor surface marker with chemical and immunological properties in common with that isolated directly from human breast adenocarcinomas.

Adenocarcinoma↗
PubMed1986

Myocardial glucose utilization in ischaemic heart disease: preliminary results with F18-fluorodeoxyglucose and positron emission tomography.

Regional myocardial utilization of glucose can be assessed non-invasively in man with the sugar analogue F18-2-fluoro-2-deoxyglucose (FDG) and positron emission tomography (PET). The preliminary observations made in patients with different clinical forms of ischaemic heart disease using FDG and PET are reported. In patients with stable angina pectoris at rest, regional myocardial glucose utilization was comparable to that in normal volunteers whilst an increased utilization of glucose was found in the recovery from exercise-induced ischaemia in the regions that showed an abnormal perfusion during the stress test. These metabolic changes persisted in the recovery phase when all the parameters that were altered during the exercise, including myocardial perfusion, had normalized. In patients with unstable angina, characterized by repeated episodes of spontaneous ST depression, myocardial glucose utilization was regionally or globally increased already at rest in the absence of symptoms or signs of ischaemia at the time of study and most often without evident perfusion abnormalities. In patients with a recent infarction, two different patterns of glucose utilization in the infarcted area have been described: a concordant decrease of myocardial perfusion and glucose utilization; a disproportionately increased glucose utilization relative to perfusion interpreted as an index of the presence of ischaemic, but still viable myocardium.

Angina Pectoris↗
PubMed1986

Local coronary supersensitivity to diverse vasoconstrictive stimuli in patients with variant angina.

It has been shown in different groups of patients with variant angina that coronary spasm can be reproduced by physiologic maneuvers and pharmacologic agents. It is not known, however, to what extent different stimuli can induce spasm in the same patient. To investigate whether coronary arterial spasm results from specific abnormal agonist-receptor interactions or from a local nonspecific coronary supersensitivity to different stimuli, 28 patients with vasospastic angina were submitted to a series of diverse vasoconstrictive stimuli known to provoke coronary spasm. Ergonovine, hyperventilation, handgrip, cold pressor, and exercise-tests, were carried out in all 28 patients. In the last 15 patients histamine was also administered. Spasm was provoked by ergonovine in 96% of patients, by hyperventilation in 54%, by histamine in 47%, by exercise in 46%, and by the cold pressor and handgrip tests in 11% and 7%, respectively. No significant differences were found in the responses to provocative tests of patients with normal coronary arteries or nonsignificant stenoses and those with significant lesions. In the same individual, spasm was induced by at least two vasoconstrictive stimuli, although with a different mechanism of action, in 82% of patients and spasm was induced by three or more stimuli in 39%. Tests were repeated in at least 23 patients and short-term reproducibility paralleled sensitivity. These results suggest that in patients with variant angina, a local nonspecific supersensitivity rather than an abnormal specific agonist-receptor interaction plays a major role in the genesis of coronary arterial spasm.

Adult↗
PubMed1986

Prolonged metabolic recovery allows late identification of ischemia in the absence of electrocardiographic and perfusion changes in patients with exertional angina.

Regional myocardial perfusion and exogenous glucose uptake were assessed in 10 normal subjects and 10 patients with coronary artery disease and stable angina pectoris using 82Rubiduim and 18F-2-fluoro-2-deoxyglucose with positron emission tomography. At rest regional myocardial perfusion and glucose uptake in patients were comparable with those in normals. In 7 patients and 5 normals a supine bicycle exercise test was performed within the positron camera. In all 7 patients, exercise induced typical chest pain and ischemic electrocardiographic changes accompanied by regional abnormalities of myocardial perfusion which normalized 5 to 14 minutes after the end of exercise. In these patients 18F-2-fluoro-2-deoxyglucose was injected during recovery from exercise when all the parameters that were altered during the test, including myocardial perfusion, were back to control. In all 7, glucose uptake in the regions which showed abnormal perfusion during exercise was significantly higher than in the non ischemic regions (i.e. the ones with a normal increment of 82Rubidium uptake during exercise). In 2 patients the test was repeated on a different day and 18F-2-fluoro-2-deoxyglucose was injected during exercise in the presence of frank ischemia. In contrast to the injection following exercise, in both patients, glucose uptake in the ischemic region was found to be lower than in the non ischemic ones. In conclusion, in patients recovering from exercise-induced ischemia exogenous glucose utilization is enhanced in the previously ischemic myocardium. This occurs in the absence of symptoms and electrocardiographic changes and allows the identification and location of previous myocardial ischemia.

Angina Pectoris↗
PubMed1985

Improved coronary supply: prevailing mechanism of action of nitrates in chronic stable angina.

Exercise tolerance before and after sublingual isosorbide dinitrate (ISDN), 10 mg, was assessed in 217 consecutive patients with stable angina, positive exercise test, and angiographically proved coronary artery disease. In 65 patients (30%), ISDN prevented exercise-induced ST segment depression and/or increased exercise time to 1 mm ST segment depression (greater than or equal to 3 minutes), despite the significantly higher (greater than or equal to 25 X 10(2) increment) rate-pressure product attained (increased coronary reserve). On the contrary, in 40 other patients, exercise test remained positive, and neither time to 1 mm ST segment depression nor rate-pressure product increased significantly (fixed coronary reserve). The remaining 106 patients had an intermediate response. To assess the mechanisms underlying the beneficial action of nitrates, we further investigated 13 patients with increased coronary reserve (group 1) and five with fixed coronary reserve (group 2) by the exercise response to ISDN and verapamil, the changes in left ventricular volumes after ISDN and verapamil, the ECG response to intravenous ergonovine, and the changes in coronary stenosis severity following intravenous ergonovine and intracoronary nitrates. ISDN dramatically improved exercise capacity only in group 1 patients. However, it induced a significant reduction of left ventricular volumes in both groups (p less than 0.01). Ergonovine provoked angina and ST segment depression in 62% of group 1 patients and significantly increased the severity of their coronary stenoses (p less than 0.01). In all group 2 patients, ergonovine was negative, and no significant increase in stenosis severity was observed. Intracoronary nitrates reduced stenosis severity in group 1 (p less than 0.01) but not in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Referrals by traditional birth attendants in northeast Brazil.

Between October 1980 and July 1981, 1,878 women were attended by traditional birth attendants (TBAs) at four obstetric units in rural areas surrounding the city of Fortaleza in Northeast Brazil. Of these women, 232 (12.4 per cent) were referred to a hospital in Fortaleza for delivery. The most important indicators for referral to hospital were: presence of an antenatal problem, complication of labor, or malpresentation. Based on record review, 65 referred women with none of these conditions were classified as low risk and 42 women not referred were classified as high risk (at least one such condition present). Of 1,878 deliveries, 32 (17 per 1,000) terminated as fetal deaths, and 12 infants died before discharge from hospital or obstetric unit (six per 1,000). The death rate was much higher for the high-risk cases (156 per 1,000 referrals, 95 for nonreferrals). Although some women may have been inappropriately referred while others who should have been were not referred, the system of referral has allowed TBAs to attend uncomplicated deliveries and to refer women with complications.

Adolescent↗
PubMed1984

Method of payment and the cesarean birth rate in a hospital in northeast Brazil.

This paper examines factors associated with the cesarean birth rate, including medical condition and method of payment, in the largest maternity hospital of Fortaleza, Brazil. Data were collected on 5996 women who delivered at the Maternidade Escola Assis Chateaubriand from October 1980 to July 1981. All women were classified according to how they paid for their care: private (financed at least part of their care with own funds), insured (federal or state), or indigent. Private patients were found to be far more likely than patients in the other two groups to have cesarean deliveries, due primarily to the high percentage of private patients recorded as having prolonged or obstructed labor, combined with a high rate of prior cesarean sections. From this data, it appears likely that financial incentives did play a role in physician decisions on whether to perform cesarean deliveries.

Brazil↗