Biomedical subjects

A C Brito

Publications and source records attributed to A C Brito.

At least 19 recordsLinked to original sources

PubMed2005

Inefficacy of piracetam in the prevention of painful crises in children and adolescents with sickle cell disease.

Analgesia and hydration remain the only safe treatment for painful crises of sickle cell disease; hydroxyurea is effective, but the toxicity is still a problem. Piracetam is a nootropic drug that has reportedly been effective and non-toxic in sickle cell patients, but most studies were not placebo-controlled and included a small number of patients. The present study evaluated the drug in a double-blind crossed placebo-controlled clinical trial in 73 children and adolescents suffering from moderate to severe painful crises for 13 months. Information regarding frequency and severity of pain was acquired through monthly clinical evaluation, visits and house calls, and 4,300 weekly questionnaires filled out by the patients in their domiciles. A monthly pain score was calculated for each patient. Pain was the most frequent adverse manifestation of the disease stressing its significant bio-psycho-social impact. Although nearly all patients and relatives reported a better clinical course throughout the whole study, the drug was ineffective in the prevention of painful crises. This placebo effect may be ascribed to an unplanned and unsystematic 'cognitive-behavioural' management of the children. The pain score in the second semester of the study - both in the experimental and in the control groups - was significantly smaller than that in the first semester. In conclusion, piracetam was found to be ineffective in the prevention of painful crises; a powerful placebo effect due to adequate patient care was demonstrated.

Adolescent↗

PubMed2004

[Present status of bancroftian filariasis in Maceió, State of Alagoas, Brazil].

Epidemiological and entomological surveys were carried out in the human and mosquito populations in Maceió, Alagoas, in order to assess the present status of bancroftian lymphatic filariasis. Examination of thick blood smears of 10,450 students from different areas of the city revealed 0.66% Wuchereria bancrofti microfilaria carriers. The distribution of filariasis is focal in the city, 80% of the individuals with patent infection living in two neighboring areas with 1.24% and 5.25% prevalence. Parallel studies performed with samples of all age groups in the human population showed similar microfilaria prevalence rates observed previously in the student survey. However, thick blood smears taken from members of families with at least one subject with patent infection gave a prevalence six times greater suggesting, increased transmission in households. The percentage of carriers was higher in the youngest age group (< 20 years). Culex quinquefasciatus mosquitos caught at the locations where the autochthonous cases were found presented natural infection rates ranging from 0.28% to 4.62%. The combination of all these findings indicates occurrence of active transmission of W. bancrofti in the urban area of Maceió, Alagoas State. Based on these data, measures for the potential control of filariasis were planned.

English Abstract↗

PubMed2000

The microfilarial periodicity of Wuchereria bancrofti in north-eastern Brazil.

The periodicity of Wuchereria bancrofti microfilariae (mff) in peripheral blood was analysed in 42 microfilaraemics living in Maceió, in Alagoas state, north-eastern Brazil. Nine blood samples were collected from each subject, over a 24-h period, and two quantitative (60-microliter) thick smears were prepared from each sample. Although all the subjects had detectable microfilaraemias from 23.00 hours to 06.00 hours, no mff could be detected in most (71.4%) of the smears prepared from samples collected at 15.00 hours. Samples collected during the day, at 15.00 hours, contained 170 times fewer mff/microliter than those collected at 01.00 hours, when microfilaraemias were generally most intense. For diagnosis of bancroftian filariasis in Maceió, blood samples should be collected between 22.00 and 03.00 hours, when microfilarial counts will be at least 90% of the peak counts. The circadian variation observed was independent of the subject's gender and microfilarial density. Mathematical analysis, using a simple harmonic-wave model, indicated a periodicity index of 127.6 and that maximum microfilarial densities occurred at 00.51 hours, confirming the nocturnal pattern of microfilaraemia in the study area.

Adolescent↗

PubMed1998

Autoradiographic thyroid evaluation in short-term experimental diabetes mellitus.

Previous studies have shown that in vitro thyroid peroxidase (TPO) iodide oxidation activity is decreased and thyroid T4-5'-deiodinase activity is increased 15 days after induction of experimental diabetes mellitus (DM). In the present study we used thyroid histoautoradiography, an indirect assay of in vivo TPO activity, to determine the possible parallelism between the in vitro and in vivo changes induced by experimental DM. DM was induced in male Wistar rats (about 250 g body weight) by a single i.p. streptozotocin injection (45 mg/kg), while control (C) animals received a single injection of the vehicle. Seven and 30 days after diabetes induction, each diabetic and control animal was given i.p. a tracer dose of 125I (2 microCi), 2.5 h before thyroid excision. The glands were counted, weighted, fixed in Bouin's solution, embedded in paraffin and cut. The sections were stained with HE and exposed to NTB-2 emulsion (Kodak). The autohistograms were developed and the quantitative distribution of silver grains was evaluated with a computerized image analyzer system. Thyroid radioiodine uptake was significantly decreased only after 30 days of DM (C: 0.38 +/- 0.05 vs DM: 0.20 +/- 0.04%/mg thyroid, P < 0.05) while in vivo TPO activity was significantly decreased 7 and 30 days after DM induction (C: 5.3 and 4.5 grains/100 micron 2 vs DM: 2.9 and 1.6 grains/100 micron 2, respectively, P < 0.05). These data suggest that insulin deficiency first reduces in vivo TPO activity during short-term experimental diabetes mellitus.

Analysis of Variance↗

PubMed1998

Bancroftian filariasis in Maceio, state of Alagoas, Brazil: Observations on Culex quinquefasciatus after blood feeding on individuals with different densities of microfilariae in the peripheral blood stream.

Females of laboratory-reared Culex quinquefasciatus were allowed to take blood meals on individuals with low (1-100 microfilariae/ml of peripheral blood), moderate (101-500 microfilariae/ml), and high (> 500 microfilariae/ml) microfilaremia. The mosquitoes ingested 1.39-3.80 microl of blood and infective third-stage (L3) larvae were first recorded 13-14 days after the infecting blood meal. The number of microfilariae ingested by mosquitoes was proportional to the density of microfilariae in the peripheral blood of the human subjects, but with a concentration factor of up to 6.5 times the expected number. Survival of mosquitoes was not influenced by the density of microfilariae in the peripheral blood of infected individuals. Infectivity indices were proportional to microfilaremia in human subjects. The number of L3 larvae/female (intensity of infection) was not influenced by individual microfilaremia. The highest vector efficiency and the best experimental infection index were recorded in mosquitoes that blood fed on individuals with moderate microfilaremia. The results are discussed in relation to the transmission on Bancroftian filariasis in the study area.

Adolescent↗

PubMed1997

Open clinical study of the efficacy and safety of terbinafine cream 1% in children with tinea corporis and tinea cruris.

BACKGROUND: Topical application of antifungal agents is considered the treatment of choice for dermatomycoses. Most of the available drugs are fungistatic, requiring long term treatment to prevent relapses. Terbinafine is a synthetic antifungal agent that, because of its fungicidal action, provides high cure rates and low relapse rates after short periods of treatment. METHODS: Ninety-seven children ages 2 to 15 years with a suspected diagnosis of tinea corporis and/or tinea cruris were enrolled in this open trial. After mycologic assessment to confirm diagnosis (culture and direct microscopy) terbinafine 1% cream was applied once daily during 1 week. Clinical and mycologic assessments were made at the baseline visit and on Days 7, 14 and 21. Efficacy assessment was based on 88 children (9 patients excluded by protocol violation). RESULTS: Therapy was considered effective in 92.0% (81 of 88) of patients (complete clinical and mycologic cure or mycologic cure with minimum signs and symptoms or clinical improvement, > or = 50%). Tolerability was assessed in 97 patients on an intention-to-treat basis. Adverse reactions were itching 3% (3 of 97), itching associated with erythema exacerbation 1% (1 of 97) and contact dermatitis 1% (1 of 97). CONCLUSION: Terbinafine 1% cream appears to be an effective and well-tolerated treatment for tinea corporis and tinea cruris in children.

Administration, Topical↗

PubMed1992

In vivo relaxation times and hydrogen density at 0.063-4.85 T in rats with implanted mammary adenocarcinomas.

Magnetic resonance (MR) imaging at 0.063 T, 0.17 T, 0.35 T, 2.94 T, and 4.85 T was performed in rats with implanted mammary adenocarcinomas (and in control rats) to study hydrogen density and the effects of magnetic field strength on T1 and T2 relaxation times in vivo. T1 increased by an order of magnitude and T2 decreased by a factor of two between the lowest and highest field strengths. Only about half of the increased water content of tumor, compared with that of muscle, was reflected in increased hydrogen density. The sensitivity of relaxation time change was increased at the lower field strengths. These results are of significance in understanding the effects of field strength on lesion detectability, contrast, and signal-to-noise ratio.

Adenocarcinoma↗

PubMed1987

Albumin labeled with Gd-DTPA as an intravascular, blood pool-enhancing agent for MR imaging: biodistribution and imaging studies.

Albumin is a macromolecule that remains largely confined to the vascular space after intravenous administration. Human serum albumin was paramagnetically labeled by covalently binding from nine to 18 gadolinium-DTPA (diethylenetriaminepentaacetic acid) chelates per protein molecule. This conjugate was tested in varying doses for in vivo biodistribution and effectiveness in tissue relaxation. After intravenous injection of the agent in rats, T1 relaxation times were significantly reduced in samples of the blood and in lung, heart, spleen, kidney, and brain tissue. These effects persisted at a relatively constant level for the next 30 minutes. In vivo magnetic resonance imaging of the heart and lungs of rats and rabbits confirmed the prolonged contrast-enhancing effect of the labeled albumin. These preliminary studies indicate that paramagnetically labeled macromolecules that distribute in the intravascular space may be effective for MR imaging evaluation of tissue blood volume.

Animals↗

PubMed1984

EKG-gated digital subtraction angiography in the detection of pulmonary emboli.

Detection of pulmonary emboli was investigated using electrocardiographically gated (EKG-gated) intravenous digital subtraction angiography (DSA) in 6 anesthetized and paralyzed dogs. Six autologous blood clots were introduced into the internal jugular vein of each dog and both conventional pulmonary angiography and EKG-gated DSA performed in frontal and oblique projections. When two observers scored any definite or equivocal embolus as positive, sensitivity was 82.1% for one and 92.9% for the other; the respective positive predictive values (PPV) were 88.5% and 65%. When only definite emboli were considered positive, sensitivity was 75% for one observer and 71.4% for the other; PPV was 100% for both. The authors conclude that DSA can demonstrate individual emboli with good sensitivity and excellent precision. If several emboli are present, EKG-gated DSA should prove highly accurate; however, care must be taken because overinterpretation is more likely with DSA than with conventional pulmonary angiography.

Angiography↗

PubMed1983

Nuclear magnetic resonance imaging of a fibrosarcoma tumor implanted in the rat.

Fibrosarcoma tumor cells were implanted in the hind legs of 25 rats and studied from the first to the sixth week postimplantation. Nuclear magnetic resonance imaging detected all tumors and did not yield any false-positives in five control rats. The T1 relaxation values of tumors overlapped those of muscle, and the T2 values overlapped those of fat, but the combination of the two values allowed discrimination of each of the three tissues with no overlap. The difference in relaxation time between tumor and muscle could be accounted for on the basis of water content, which was approximately 14% higher in the tumors. This study confirms data from previous studies suggesting that nuclear magnetic resonance imaging is a highly sensitive modality, but that T1 and T2 values are not specific for individual pathologic conditions.

Adipose Tissue↗

PubMed1983

Nuclear magnetic resonance contrast enhancement study of the gastrointestinal tract of rats and a human volunteer using nontoxic oral iron solutions.

Two dilute oral iron solutions, made from commonly available nonprescription dietary supplements, were found to enhance the gastrointestinal tract in nuclear magnetic resonance imaging of live rats and one human volunteer. The paramagnetic and pharmacologic properties of ferric ammonium citrate were more favorable than those of ferrous sulfate heptahydrate. The paramagnetic iron solutions shorten T1 and T2 relaxation times of water protons in the contrast media-filled gastrointestinal tract, producing easily observable change in NMR intensity. Because these iron solutions are available commercially and are known to be well tolerated, the clinical use of iron-containing NMR contrast agents for the gastrointestinal tract is feasible.

Animals↗

PubMed1981

Determination of liver, kidney, and spleen volumes by computed tomography: an experimental study in dogs.

The volume of the dog's liver, kidneys, and spleen were measured by computed tomography (CT) and a water displacement method. Organ volume determination by CT is a rapid, simple procedure that is accurate to +/- 5% of the organ volume measured by water displacement. Individual measurements were reproducible to within +/- 3%. Determination of organ volume has potential importance in a variety of clinical situations.

Animals↗

PubMed1981

Computed tomography of the liver in rhesus monkeys following losefamate meglumine administration.

Iosefamate meglumine was evaluated for potential use as a contrast agent for hepatic computed tomography (CT) in rhesus monkeys. Iosefamate meglumine in doses of 150, 300, and 450 mg I/kg was injected into four rhesus monkeys and hepatic CT attenuation values, blood iodine levels, serum enzyme levels, and hepatic histology were monitored. The hepatic CT number increased by 19 to 30 HU following a 150 mg I/kg dose and remained elevated for 15 to 45 minutes. Peak blood iodine values occurred 2 minutes postinjection but fell rapidly to less than 40% of the peak value by 45 minutes and less than 20% of peak by 4 hours. Transient elevations in serum enzyme levels were found but no histologic abnormalities were detected. Iosefamate meglumine is a potentially valuable hepatic CT contrast agent, as it produces a significant, prolonged increase in hepatic attenuation values and selectively opacifies functioning hepatocytes.

Animals↗

PubMed1981

Diagnosis of peripheral pulmonary emboli by computed tomography in the living dog.

Computed tomography (CT) provides a noninvasive alternative to arteriography in detecting central pulmonary thromboembolism. It is uncertain, however, if smaller, more peripheral clots can be diagnosed by means of CT because of the low spatial resolution and the possible motion artifacts that result from long exposure time. The peripheral pulmonary arteries of five dogs were embolized with boiled autologous clots. The location and size of the thromboemboli were then determined using arteriography. One dog died after embolization. In three of the four remaining dogs, CT scans, after slow intravenous injection of contrast material, showed the emboli as filling defects in the appropriate lobar and segmental arteries.

Animals↗

PubMed1981

Medially deployed thoracostomy tubes: cause of aortic obstruction in newborns.

It was observed that severe aortic displacement, narrowing, and obstruction can occur when thoracostomy tubes abut the mediastinum. To further investigate this previously undescribed phenomenon, aortography was performed with intraluminal pressure measurements in newborn puppies and aortograms obtained in two infant cadavers. In the puppies, when the tube tip pressed against the descending thoracic aorta, aortic pressure below that site decreased and aortic arch pressure rose. When the tube tip pressed against the ascending aorta, pressures in the aortic arch and abdominal aorta decreased. Aortography in the puppies and infant cadavers demonstrated aortic displacement, narrowing, and obstruction when the thoracostomy tubes abutted the mediastinum. The clinical consequences of malpositioned thoracostomy tubes were observed in two premature infants. When the posteromedially deployed tubes were partially withdrawn, systolic arterial pressures, which had been exceptionally low, suddenly and significantly increased distal to the tube tip. Medially deployed thoracostomy tubes may represent a potential hazard to the newborn infant.

Animals↗

PubMed1981

[Pure cutaneous cryptococcosis].

The authors present one case of cutaneous cryptococcosis, which diagnosis was confirmed by histopathologic and mycologic procedures. As there has not been systemic dissemination, this case must be considered uncommon. The lesions healed completely after treatment by amphotericin-B.

Amphotericin B↗

PubMedDate not supplied

The effect of acute pulmonary edema on pulmonary vascular resistance: significance for the interpretation of dilated upper lobe vessels on chest radiographs.

Dilation of upper lobe pulmonary vessels is an important radiographic sign of acute, left heart failure. A prominent theory is that perivascular edema causes increased resistance at the lung bases and inverts the normal perfusion gradient such that upper lobe blood flow exceeds lower lobe flow. This theoretical increase in flow is thought to cause dilatation of upper lobe vessels. Previous experimental studies determined indirectly changes in resistance from changes in the perfusion gradient: Results were contradictory. We measured directly the effect of edema on resistance in isolated canine lungs. Resistance increased linearly with edema. The magnitude of increase was small, however, and insufficient to cause inversion of the perfusion gradient. Our data indicate that interstitial pulmonary edema does not cause significant redistribution of blood flow. We suggest that dilated upper lobe vessels are veins acting as pulmonary venous manometers, reflecting elevated left atrial pressure, not increased blood flow.

Acute Disease↗

PubMedDate not supplied

Thermographic assessment of intestinal viability following ischemic damage.

Reactive hyperemia has been shown to be a characteristic of viable ischemic tissue that has been revascularized. A segment of small bowel was made ischemic by arterial occlusion and the ischemia maintained for 2 1/2 hrs (ischemic, viable bowel) or 8 hrs (ischemic, nonviable bowel) before circulation was restored. Thermograms and surface temperature measurements of exposed ischemic and non-ischemic bowel segments were obtained before and every five minutes after revascularization. Thermograms of segments revascularized after 2 1/2 hrs of ischemia demonstrated reactive hyperemia and a one to four degree increase in surface temperature compared to normal surrounding bowel. No hyperemic response was seen in bowel segments that were ischemic for 8 hrs. Our results indicate that thermograms can document reactive hyperemia of an exposed ischemic bowel that has been successfully revascularized and may be an important aid in assessing bowel viability during surgery.

Animals↗