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Biomedical subjects

M Ferreira

Publications and source records attributed to M Ferreira.

At least 37 records · Page 2Linked to original sources
PubMed2001

Evidence of a functional alpha7-neuronal nicotinic receptor subtype located on motoneurons of the dorsal motor nucleus of the vagus.

In vitro autoradiography using 125I-alpha-bungarotoxin (alpha-BGTx) and anti-alpha7 immunohistochemistry were performed on the dorsal motor nucleus of the vagus (DMV) of sham and chronically vagotomized rats to determine whether the alpha7-nicotinic acetylcholine receptor (nAChR) is located postsynaptically on DMV neurons whose axons contribute to the vagus nerve. Intense bilateral 125I-alpha-BGTx binding and anti-alpha7 immunostaining were observed in coronal brain sections containing the DMV of sham-vagotomized animals. Unilateral cervical vagotomy resulted in ipsilateral losses of 125I-alpha-BGTx binding and anti-alpha7 immunostaining from the DMV. Simultaneous staining of rat brainstem sections with anti-alpha7 and anti-choline acetyltransferase (ChAT) antibodies (to identify cholinergic DMV neurons that project into the vagus nerve) revealed that every DMV neuron that was stained for ChAT showed alpha7-staining as well. In vagotomized animals, no ChAT-positive neurons expressing alpha7-nAChRs remained in the ipsilateral DMV. We conclude that the alpha7-nAChR subtype is located postsynaptically on DMV neurons. To test whether the alpha7-nAChR is similar to the alpha7-homomeric nAChR, experiments were performed in anesthetized rats, and compounds were microinjected into the DMV while monitoring intragastric pressure (IGP). alpha-BGTx and strychnine antagonized nicotine-induced increases in IGP; no antagonism was observed with methyllycaconitine, a compound known to block the homomeric alpha7-nAChR subtype. Recovery from alpha-BGTx-induced antagonism of the nicotine response was observed. We conclude that there is a nAChR containing the alpha7-subunit in the DMV that is different from the homomeric alpha7-nAChR subtype.

Aconitine↗
PubMed2001

[Constrictive pericarditis: an early diagnosis?].

The authors report a case study of a 73-year-old male, with signs of right-sided heart failure with 6 months of evolution. It was constrictive pericarditis, without radiologic, echocardiographic and magnetic resonance imaging manifestations, diagnosed on the basis of the clinical situation and hemodynamic evaluation during cardiac catheterization. The authors suggest that the lack of imagiologic manifestations might have been the result of an early diagnosis, before the development of the classic picture. Pericardiectomy, performed with success, was followed by resolution of the heart failure. It was not possible, histologically, to draw conclusions about the etiology. The development of mitral regurgitation after pericardiectomy has enriched this case with an unusual, but previously described, complication of this type of surgery.

Aged↗
PubMed2000

Construction of a branched chain at C-3 of a hexopyranoside. Synthesis of miharamycin sugar moiety analogs.

Synthesis of the conveniently protected epimer at C-3' of the miharamycin sugar moiety was accomplished starting from the corresponding 3,3'-spiroepoxide. Reaction of the epoxide with lithium cyanide, followed by hydrolysis and spontaneous cyclization, afforded the intermediate deoxylactone methyl 4,6-O-benzylidene-3-C-(carboxymethyl)-alpha-D-glucopyranoside-3',2-lacto ne (8). Stereoselective hydroxylation with MoO5 x py x HMPA, reduction with lithium aluminum hydride and cyclization with diethyl azodicarboxylate-triphenylphosphine gave the target molecule methyl 2,3''-anhydro-4,6-O-benzylidene-3-C-[(R)-1,2-dihydroxyethyl]-alpha -D-glucopyranoside (5). Direct reduction of 8 gave other analogs having no C-3' hydroxyl group together with having a C-3'' hydroxyl group (hemiacetal). In addition, C-3' epimers were also synthesized through C-3', C-3'' dihydroxy analogs. Wittig reaction of an appropriate ketosugar with [(ethoxycarbonyl)methylene]triphenylphosphorane leading to a 7:3 Z/E mixture, followed by hydroxylation with osmium tetroxide, reduction and cyclization afforded the target molecule 5 and the miharamycin sugar moiety methyl 2,3''-anhydro-4,6-O-benzylidene-3-C-[(S)-1,2-dihydroxyethyl]-alpha -D-glucopyranoside. Examination of X-ray data for 5 and its NMR spectroscopy data allowed us to explain a contradiction reported in the literature.

Anti-Bacterial Agents↗
PubMed2000

Evidence for an involvement of vitellogenin in the steroidogenic activity of rainbow trout (Oncorhynchus mykiss) vitellogenic oocytes.

In vivo and in vitro the concentration of vitellogenin (VTG) inside the oocyte can alter VTG production by the liver, modulating the synthesis of 17beta-estradiol (E(2)) by the ovary. To gain a greater insight into this mechanism, the in vitro production of free and conjugated testosterone (T), E(2), and androstenedione (A) by rainbow trout oocytes from the early and middle vitellogenic stage was measured by radioimmunoassay. There was a decreased E(2) production that was greater in September (40%) than October (30%), by the oocytes incubated with the vitellogenic fraction. The production of E(2) conjugated as glucuronide was lower than sulfate (P < 0.05), but similar in control and VTG-incubated oocytes. Levels of free T increased from September to October, and conjugates were both produced at low levels, and no differences were detected between control and incubated VTG oocytes. The decreased synthesis of E(2) by oocytes incubated with VTG was not followed by an increase in the amount of T or conjugated E(2), because there were no differences under the two circumstances. However, there was a reduced synthesis of A with oocytes producing low levels of E(2). These results suggest that the presence of high levels of VTG in the oocyte suppresses the synthesis of A and E(2), affecting the activities of the enzymes C17,20 lyase and aromatase and probably interfering with the heme protein cytochrome P450 which in the ovary catalyses C 17,20 lyase (P450 c17) and aromatase (P450 arom).

Androstenedione↗
PubMed2000

Endocardial and epicardial radiofrequency ablation in the treatment of atrial fibrillation with a new intra-operative device.

OBJECTIVE: Atrial fibrillation has been a difficult problem to solve in many surgical patients, especially in those with mitral valve pathology. This study evaluates the results of endocardial and epicardial radiofrequency ablation with a new intra-operative device in the treatment of atrial fibrillation. METHODS: We operated on 65 patients with atrial fibrillation, 58 of which had concomitant mitral surgery. Atrial fibrillation was chronic (over 1 year) in 46 patients (group A) and paroxysmal or recent onset in 12 (group B). Group C had lone atrial fibrillation (two), concomitant coronary artery disease (four) or a sarcoma (one). Bilateral pulmonary vein isolation with a new intra-operative device was performed through multiple dry lesions in all patients. Groups A and B had endocardial applications at 70 degrees C during 60 s and group C had epicardial applications at 75 degrees C. Three group C patients had epicardial applications off pump. Atrial wall biopsies were performed in nine patients from groups A and B. RESULTS: There were no serious post-operative complications. At 1 month follow-up 54% of all patients were out of atrial fibrillation and 34% were in normal sinus rhythm with bilateral atrial contraction (Santa Crus Score 4). At 6 months follow-up, in spite of some crossover of patients among groups, similar results were obtained. The success of the procedure was 69% (Santa Crus scores 3 and 4) in mitral patients with a left atrial volume smaller than 200 cm(3). Preliminary data on the transmurality of the lesions is presented. The patients submitted to epicardial radiofrequency ablation (group C) have satisfactory results at 1 month (six out of seven were out of AF). CONCLUSIONS: Both endocardial and epicardial RF applications are simple and quick to perform and do not pose an additional risk for most patients. Furthermore we believe that it is possible to perform bilateral epicardial radiofrequency ablation of the pulmonary veins without cardiopulmonary bypass. Further refinements of the technique are needed to assure transmurality of all lesions and better results.

Atrial Fibrillation↗
PubMed2000

Reversal of morphine-induced apnea in the anesthetized rat by drugs that activate 5-hydroxytryptamine(1A) receptors.

The purpose of our study was to test the hypothesis that 5-hydroxytryptamine (5-HT)(1A) receptor agonists counteract morphine-induced respiratory depression. Studies were conducted in anesthetized rats, and respiratory activity was monitored with diaphragm electromyography. Morphine was administered i.v. in doses that produce apnea. Once apnea was established, i.v. administration of the 5-HT(1A) receptor agonist drug 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) at 10 or 100 microgram/kg restored normal breathing in each animal (n = 24). This antagonistic effect of 8-OH-DPAT on morphine-induced respiratory depression was observed in both spontaneously breathing and artificially ventilated animals. Results obtained with 8-OH-DPAT were mimicked by buspirone (50 microgram/kg i.v.), another 5-HT(1A) receptor agonist drug. Pretreatment with 4-(2'-methoxyphenyl)-1-[2'[N-(2'-pyridinyl]-p-iodo-benzamido]ethyl]pi perazine, an antagonist of 5-HT(1A) receptors, prevented 8-OH-DPAT from counteracting morphine-induced apnea. These results indicate that activation of central nervous system 5-HT(1A) receptors is an effective way of reversing morphine-induced respiratory depression. Most important, this is the third model of disturbed respiratory function in which drugs that stimulate 5-HT(1A) receptors have been shown to restore breathing to near-normal levels.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2000

Brainstem nicotinic receptor subtypes that influence intragastric and arterial blood pressures.

The purpose of this study was to investigate the effect of microinjection of nicotine and nicotinic receptor antagonists into the dorsal motor nucleus of the vagus (DMV) or medial subnucleus of the tractus solitarius (mNTS) on intragastric (IGP) and arterial blood pressures (BP) in anesthetized rats. Nicotine microinjected into the DMV (10-300 pmol) produced dose-related increases in IGP (ED(50) = 89 pmol); no significant changes were noted for BP. Ipsilateral vagotomy abolished nicotine-induced increases in IGP. Nicotine microinjected into the mNTS in a dose range of 0.1 to 300 pmol produced dose-related decreases in IGP (ED(50) = 0.6 pmol) and BP (ED(50) = 5.4 pmol). Bilateral vagotomy abolished nicotine-induced decreases in IGP while having no effect on BP. In rats treated with daily s.c. injections of nicotine (0.8 mg/kg of base) for 10 days, microinjections of nicotine into the DMV produced similar increases in IGP. BP responses from the mNTS were not affected by chronic treatment. However, nicotine microinjections into the mNTS no longer produced a decrease in IGP in these chronically treated animals. alpha-Bungarotoxin (100 pmol) significantly blocked nicotine-evoked increases in IGP from the DMV while having no effect on nicotine-induced responses elicited from the mNTS. Hexamethonium (10 and 100 pmol) microinjected into the mNTS dose-dependently blocked nicotine-induced effects but did not interfere with the action of nicotine at the DMV. Our data indicate that nicotine-induced changes in IGP result from nicotine acting at two sites, the DMV and mNTS; and that at least three different nicotinic receptors in the dorsal medulla oblongata can influence gastrointestinal and cardiovascular function.

Animals↗
PubMed1999

Effects of calcium beta-hydroxy-beta-methylbutyrate (HMB) supplementation during resistance-training on markers of catabolism, body composition and strength.

Calcium beta-hydroxy-beta-methylbutyrate (HMB) supplementation has been reported to reduce muscle catabolism and promote gains in fat-free mass and strength in subjects initiating training. However, whether HMB supplementation promotes these adaptations in trained athletes is less clear. This study examined the effects of HMB (as the calcium salt) supplementation during resistance training (6.9+/-0.7 hr x wk(-1)) on markers of catabolism, body composition and strength in experienced resistance-trained males. In a double-blind and randomized manner, 40 experienced resistance-trained athletes were matched and assigned to supplement their diet for 28 d with a fortified carbohydrate/protein powder containing either 0, 3 or 6 g x d(-1) of calcium HMB. Fasting venous blood and urine samples, dual energy X-ray absorptiometer-determined body composition, and isotonic bench press and leg press one repetition maximums (1 RM) were determined prior to and following 28 d of supplementation. HMB supplementation resulted in significant increases in serum and urinary HMB concentrations. However, no statistically significant differences were observed in general markers of whole body anabolic/catabolic status, muscle and liver enzyme efflux, fat/bone-free mass, fat mass, percent body fat, or 1 RM strength. Results indicate that 28 d of HMB supplementation (3 to 6 g x d(-1)) during resistance-training does not reduce catabolism or affect training-induced changes in body composition and strength in experienced resistance-trained males.

Adult↗
PubMed1999

Electrosurgical treatment of atrial fibrillation with a new intraoperative radiofrequency ablation catheter.

BACKGROUND: To assess the efficacy of a new catheter for intraoperative radiofrequency ablation. METHODS: We operated 35 mitral patients with atrial fibrillation of which 27 had chronic atrial fibrillation with a mean duration of 8 +/- 6 years. Most patients were in functional class III or IV. All patients were operated under cardiopulmonary bypass using sternotomy in 29 patients, right thoracotomy in 5 and left thoracotomy in 1. RESULTS: Bilateral pulmonary vein isolation with radiofrequency catheter ablation was achieved in 7 +/- 4 minutes. There was no mortality or morbidity. Out of the 27 patients with one to three months follow-up 60% were out of atrial fibrillation and 48% had both atria contracting (scores 3 and 4). A longer time is required to assess the end result of these techniques, because the complete healing of the ablation lesions takes 3 to 6 months. CONCLUSIONS: We conclude that with appropriate tools and settings the use of intraoperative radiofrequency catheter ablation is fast, safe and effective. Its indications can be extended to other types of atrial fibrillation patients.

Aged↗
PubMed1999

Imerslund-Gräsbeck syndrome in an African patient.

Imerslund-Gräsbeck syndrome (IGS) is a rare cause of megaloblastic anaemia in young children. We wish to report the first case described from Africa. The diagnosis of IGS was made on the findings of a low vitamin B12 level, mild proteinuria, and a vitamin B12 absorption test unaffected by the intrinsic factor. The patient responded well to treatment with intramuscular vitamin B12.

Anemia, Megaloblastic↗
PubMed1999

Relocation of the iliac artery bifurcation to facilitate endoluminal treatment of abdominal aortic aneurysms.

PURPOSE: To report a surgical technique to preserve the internal iliac arteries (IIAs) and facilitate endovascular repair of abdominal aortic aneurysms (AAAs) with extensive iliac artery involvement. TECHNIQUE: A new iliac artery bifurcation is created surgically through an 8-cm lower left abdominal incision by implanting the IIA onto the distal external iliac artery either directly or by using a tube graft interposition. Careful technique is required to avoid embolic complications, but after relocating the bifurcation, aortic endografting can be performed, either simultaneously or staged, depending upon patient characteristics. CONCLUSIONS: Relocation of the iliac artery bifurcation appears to be a good alternative to preserve pelvic arterial flow in selected candidates for endoluminal AAA repair.

Anastomosis, Surgical↗
PubMed1999

[Time integral of oxygen pulse for exercise submaximal levels in patients with heart insufficiency--correlation with maximal oxygen consumption].

UNLABELLED: Maximal oxygen consumption (VO2max) has an important prognostic value in patients with congestive heart failure (CHF). However, it requires a maximal exercise test, not often available for these patients. To overcome this limitation, we examined whether a simple time integral of oxygen pulse (OP) to submaximal exercise levels correlates with VO2max. METHODS: We performed a maximal symptom-limited treadmill exercise test, while measuring breath-by-breath oxygen consumption, using the CAEP protocol, in 24 patients with CHF (51 +/- 11 years, 18 males, sinus rhythm). No exercise was terminated due to ischemia or arrhythmias. All patients attained anaerobic threshold. Besides standard parameters, OP (ml) and time integral of OP (OPTI) were calculated at 2 minutes (OP-2 min and OPTI-2 min) and at 4 minutes (OP-4 min and OPTI-4 min) of exercise. Patients were divided in two groups according to VO2max: group I--VO2max > or = 16 ml/kg/min (14 patients) and group II--VO2max < 16 (10 patients). RESULTS: Age, sex, body surface and CHF etiology were similar in both groups. Exercise duration, maximal OP, time to anaerobic there shold, VO2 and OP at anaerobic there shold were higher in group I (p < 0.05). Comparing group I vs group II--OP-2 min: 6.2 +/- 1.5 vs 5.0 +/- 1.2 ml (p = 0.026); OP-4 min: 7.6 +/- 1.9 vs 5.4 +/- 1.2 (p = 0.001); OPTI-2 min: 3.1 +/- 1.1 vs 2.2 +/- 0.9 (p = 0.021) and OPTI-4 min: 15.2 +/- 4.4 vs 9.3 +/- 3.1 (p = 0.0007). The best correlation with VO2max was obtained for OPTI-4 min (r = 0.696). An OPTI-4 min value > or = 10 occurred in 13 patients of group I and in two patients of group II (p = 0.00013), with a predictive value of 87% for VO2max > 16 (sensitivity = 93%, specificity = 80%)--kappa index = 0.739. CONCLUSIONS: OPTI-4 min can be a useful tool for assessing cardiocirculatory functional status in patients with CHF and unable to perform a maximal exercise test.

Adult↗
PubMed1999

[The metabolic-chronotropic relation in patients with heart failure--a correlation with functional capacity].

UNLABELLED: Previous studies on chronotropic incompetence (CI) in patients with congestive heart failure (CHF) have defined it as the inability to achieve > 80% of age predicted maximum heart rate (HR) (adequacy of HR response to submaximal exercise levels not being considered). The metabolic chronotropic relation (MCR) concept proposed by Wilkoff allows the assessment of the entire chronotropic function. The value of such an approach for the evaluation of CI in patients with CHF, and its relation to exercise capacity, is unclear at present. METHODS: We imposed maximal symptom-limited treadmill exercise testing while measuring breath-by-breath oxygen consumption, using CAEP protocol, in 25 patients (19 men), 49 +/- 10 years, all in sinus rhythm, with CHF secondary to dilated cardiomyopathy (17) or ischemic heart disease (8), NYHA class II-III. Anaerobic threshold (AT) was attained by all. No exercise was terminated due to arrhythmia or ischemia. MCR was calculated as the slope of the relation between the percentages of HR and metabolic reserves achieved at the end of each exercise stage. Using 2.0 standard deviations below the mean level of MCR in healthy controls, we defined an MCR value < 0.84 as abnormal. The parameters analysed were: age, drug therapy, fractional shortening (FS-%), resting HR (RHR-bpm), exercise duration (DUR-min), peak HR (HRp), peak oxygen consumption (VO2p-ml/kg/min), percentages of predicted maximal HR (% PMHR) and VO2 (% PMVO2), peak ventilatory equivalent for CO2 (VE/VCO2-L/min), time to AT (T-AT), and VO2 at AT (VO2-AT). RESULTS: MCR was normal (1.01 +/- 0.18-0.86 to 1.19) in 10 patients--Group I, and abnormal (0.66 +/- 0.13-0.42 to 0.81) in 15 (60%) patients--Group II. A similar proportion of patients in both groups were taking ACE inhibitors, digoxin and amiodarone. [table: see text] CI defined as an inability to achieve a % PMHR > 80% occurred only in 6 (24%) patients, all in Group 2 (p = 0.022 versus abnormal MCR). CONCLUSIONS: In CHF patients, CI assessed as an abnormal MCR is frequent, and relates to an impaired exercise capacity.

Adult↗
PubMed1998

Umbilical hernia of stomach.

Herniation of the stomach through the umbilicus is exceedingly rare with only one case reported in the international literature in the past 40 years. One case of a reducible gastric umbilical hernia, not diagnosed by endoscopy, is reported. Diagnosis was made by double-contrast barium examination after 5 years of symptoms and ineffective treatment. Herniation of the stomach is difficult to diagnose by endoscopy and radiological studies can be more sensitive and allow a more specific diagnosis.

Barium Sulfate↗
PubMed1998

Quantification of total chromium and hexavalent chromium in UHT milk by ETAAS.

Procedures for the quantification of total chromium and hexavalent chromium in UHT milk samples are presented. Total chromium was determined directly in milk with the addition of a surfactant and a mixture of Pd and Mg as a chemical modifier. For the selective separation of hexavalent chromium, the sample pre-treatment consisted in precipitation of proteins and elution of the supernatant through a Chromabond NH2 column. The metal was eluted with nitric acid. Both total chromium and hexavalent chromium were evaluated by atomic absorption spectrometry with electrothermal atomization using the same instrumental conditions. The detection limits were 0.2 and 0.15 microgram l-1 for total chromium and hexavalent chromium, respectively. The linearity ranges under the optimized conditions were 0.2-20 and 0.15-50 micrograms l-1. For total chromium the precision was 4.9 and 5.7% for the analytical and the over-all procedure, respectively, and for hexavalent chromium 4.3 and 4.9%, respectively. The validation of both procedures was performed by the standard additions method and the recoveries were higher than 93% in all cases. For total chromium, a certified reference material was also used to validate the methodology. The methods were applied to the determination of total chromium and hexavalent chromium in 60 UHT milk samples.

Animals↗
PubMed1998

Effects of creatine supplementation on body composition, strength, and sprint performance.

PURPOSE: To determine the effects of 28 d of creatine supplementation during training on body composition, strength, sprint performance, and hematological profiles. METHODS: In a double-blind and randomized manner, 25 NCAA division IA football players were matched-paired and assigned to supplement their diet for 28 d during resistance/agility training (8 h x wk[-1]) with a Phosphagen HP (Experimental and Applied Sciences, Golden, CO) placebo (P) containing 99 g x d(-1) of glucose, 3 g x d(-1) of taurine, 1.1 g x d(-1) of disodium phosphate, and 1.2 g x d(-1) of potassium phosphate (P) or Phosphagen HP containing the P with 15.75 g x d(-1) of HPCE pure creatine monohydrate (HP). Before and after supplementation, fasting blood samples were obtained; total body weight, total body water, and body composition were determined; subjects performed a maximal repetition test on the isotonic bench press, squat, and power clean; and subjects performed a cycle ergometer sprint test (12 x 6-s sprints with 30-s rest recovery). RESULTS: Hematological parameters remained within normal clinical limits for active individuals with no side effects reported. Total body weight significantly increased (P < 0.05) in the HP group (P 0.85 +/- 2.2; HP 2.42 +/- 1.4 kg) while no differences were observed in the percentage of total body water. DEXA scanned body mass (P 0.77 +/- 1.8; HP 2.22 +/- 1.5 kg) and fat/bone-free mass (P 1.33 +/- 1.1; HP 2.43 +/- 1.4 kg) were significantly increased in the HP group. Gains in bench press lifting volume (P -5 +/- 134; HP 225 +/- 246 kg), the sum of bench press, squat, and power clean lifting volume (P 1,105 +/- 429; HP 1,558 +/- 645 kg), and total work performed during the first five 6-s sprints was significantly greater in the HP group. CONCLUSION: The addition of creatine to the glucose/taurine/electrolyte supplement promoted greater gains in fat/bone-free mass, isotonic lifting volume, and sprint performance during intense resistance/agility training.

Adult↗