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Biomedical subjects

M S Rocha

Publications and source records attributed to M S Rocha.

At least 19 recordsLinked to original sources
PubMed2006

Characterization of objective transmittance for optical tweezers.

We have measured the overall transmittance of a laser beam through an oil immersion objective as a function of the transverse size of the laser beam, using the dual-objective method. Our results show that the objective transmittance is not uniform and that its dependence on the radial beam's position can be modeled by a Gaussian function. This property affects the intensity distribution pattern in the sample region and should be taken into account in theoretical descriptions of optical tweezers. Moreover, one must consider this position dependence to determine the local laser power delivered at the sample region by the dual-objective method, especially when the beam overfills the objective's back entrance. If the transmittance is assumed to be uniform, the local power is overestimated.

Computer Simulation↗
PubMed2005

Low bone density and low serum levels of soluble RANK ligand are associated with severe arterial calcification in patients with Takayasu arteritis.

OBJECTIVE: Takayasu arteritis (TA) is a chronic inflammatory disorder affecting the aorta and its branches. Vascular calcification has been described in 29-54% of cases of TA, although its aetiology remains unknown. Recently the osteoprotegerin/RANKL/RANK system has emerged as an important contributing factor to atherogenesis and osteogenesis. Our aim is to investigate the association between vascular calcification, bone mineral density (BMD) and the osteoprotegerin/RANK/RANKL system in TA. METHODS: Thirty pre-menopausal female TA patients and 30 age- and sex-matched controls were studied. BMD was measured by dual X-ray absorptiometry. Arterial calcification in TA patients was analysed by computed tomography in thoracic and abdominal sites. Serum levels of osteoprotegerin and soluble receptor activator of nuclear factor kappaB ligand (sRANKL) were quantified by enzyme-linked immunosorbent assay. RESULTS: Patients with severe arterial calcification showed lower BMD values than controls in lumbar spine (0.965 +/- 0.055 vs 1.126 +/- 0.153 g/cm2, P = 0.009) and total body (0.993 +/- 0.065 vs 1.085 +/- 0.082 g/cm2, P = 0.019). In contrast, TA patients without calcification presented BMD values similar to controls (P > 0.05). Interestingly, lower serum levels of sRANKL (1.89 +/- 2.35 vs 2.80 +/- 2.23 pg/ml, P = 0.031) and a longer disease duration (12.20 +/- 6.61 vs 3.56 +/- 5.33 yr, P = 0.004) were observed in TA patients with severe calcification compared with patients without calcification. CONCLUSIONS: Severe arterial calcification in TA is associated with low values of BMD and sRANKL, reinforcing the possible link between bone and vascular disease.

Adult↗
PubMed2004

DNA-psoralen interaction: a single molecule experiment.

By attaching one end of a single lambda-DNA molecule to a microscope coverslip and the other end to a polystyrene microsphere trapped by an optical tweezers, we can study the entropic elasticity of the lambda-DNA by measuring force versus extension as we stretch the molecule. This powerful method permits single molecule studies. We are particularly interested in the effects of the photosensitive drug psoralen on the elasticity of the DNA molecule. We have illuminated the sample with different light sources, studying how the different wavelengths affect the psoralen-DNA linkage. To do this, we measure the persistence length of individual DNA-psoralen complexes.

Chemistry, Physical↗
PubMed2001

[Cerebral vasculitis and Basedow-Graves disease: report of two cases].

OBJECTIVE: To report two cases of patients with cerebral vasculitis and Basedow-Graves disease. CASE REPORT: Two young female patients presented at emergency with acute neurological picture of hemiparesis and speech distress. The first patient, 22 year-old, has been on clinical treatment for hyperthyroidism for one month. On clinical examination she had an elevated cardiac rate, bilateral exophthalmia and a diffuse goiter. On neurological examination we could observe a mild dysarthria and left hemiparesis. The second patient was a 15 year-old girl, who presented sudden conscious loss, aphasia and right hemiparesis. RESULTS: CT scan and MRI showed areas of cerebral infarcts. Angiographic study showed multiple vascular stenosis similar to an arteritic angiographic pattern. Extensive medical and laboratorial workout disclosed no other risk factor for stroke or for nervous system vasculitis. The antimicrosomal and antithyreoglobulin antibodies were positive and thyroidian hormones confirmed hyperthyroidism. CONCLUSION: The concurrence of cerebral arteritis and Basedow-Graves' disease suggest a possible pathogenic link between Graves' disease and specific cerebral vascular disorders, possibly through a common autoimmune mechanism.

Adolescent↗
PubMed2001

[Relapsing polychondritis associated with meningoencephalitis: case report].

Polychondritis is a disease manifesting as an episodic inflammation of cartilagenous structures throughout the body with progressive course. We describe a patient with a presentation picture of two episodes of meningoencephalitis and after the outcome with polychondritis. Neurological involvement is rare in this disease as neurologic presenting symptoms do. The diagnostic precision was determinant for a satisfactory outcome with corticosteroids and methotrexate.

Antirheumatic Agents↗
PubMed2001

[Cerebrovascular disease and neurocysticercosis].

We report three cases of stroke secondary to neurocysticercosis. The first one is a 36 years old man with bilateral middle cerebral artery occlusions who had presented acute right hemiparesia and aphasia. MRI demonstrated several enhancing subarachnoid cysts surrounding the occluded vessels, a right parietal racemose cyst and a left temporal large infarction area. Angiographic study showed total occlusion of left middle cerebral artery and a subtotal occlusion of right middle cerebral artery. The second one is a 42 years old man with vasculitis of small cortical vessels who presented with headache, seizures and focal neurological deficit. CT scan demonstrated several calcifications and a left temporal infarction area. Cerebral angiographic study was normal. The third case was a woman, 53 years old, with a past history of six stroke events and an actual behavior disturbance and seizures. MRI demonstrated several cortical and subcortical infarction areas and cisternal cysts. Angiographic study showed diffuse arteritis of basilar and carotid arterial system. In all three cases CSF study showed linfomonocitic pleocytosis and positive ELISA for cysticercosis.

Adult↗
PubMed2000

[Miller fisher syndrome and optic neuritis: case report].

We report a case of Miller Fisher syndrome and bilateral demyelinating optic neuropathy suggesting the possible involvement of central nervous system in this syndrome. The optic neuritis was confirmed by visual evoked potential.

Adult↗
PubMed2000

[Lafora's disease: diagnosis by muscle biopsy (case report)].

A 16-year-old female patient had myoclonic epilepsy caused by Lafora's disease. Muscle biopsy showed a prominent splitting pattern in muscle fibers with the nicotinamide adenine nucleotide dehydrogenase-tetrazolium reductase reaction, hematoxylin-eosin, and PAS stains. This morphologic appearance of the tissue permits diagnosis using the benign technique of muscle biopsy. The ultrastructural examination of muscle may be necessary to confirm the diagnosis of Lafora myoclonus epilepsy if light microscopical findings are equivocal.

Adolescent↗
PubMed2000

Safety and efficacy of angioplasty with intracoronary stenting in patients with unstable coronary syndromes. Comparison with stable coronary syndromes.

OBJECTIVE: To assess safety and efficacy of coronary angioplasty with stent implantation in unstable coronary syndromes. METHODS: Retrospective analysis of in-hospital and late evolution of 74 patients with unstable coronary syndromes (unstable angina or infarction without elevation of the ST segment) undergoing coronary angioplasty with stent placement. These 74 patients were compared with 31 patients with stable coronary syndromes (stable angina or stable silent ischemia) undergoing the same procedure. RESULTS: No death and no need for revascularization of the culprit artery occurred in the in-hospital phase. The incidences of acute non-Q-wave myocardial infarction were 1.4% and 3.2% (p = 0.6) in the unstable and stable coronary syndrome groups, respectively. In the late follow-up (11.2 +/- 7.5 months), the incidences of these events combined were 5.7% in the unstable coronary syndrome group and 6.9% (p = 0.8) in the stable coronary syndrome group. In the multivariate analysis, the only variable with a tendency to significance as an event predictor was diabetes mellitus (p = 0.07; OR = 5.2; 95% CI = 0.9-29.9). CONCLUSION: The in-hospital and late evolutions of patients with unstable coronary syndrome undergoing angioplasty with intracoronary stent implantation are similar to those of the stable coronary syndrome group, suggesting that this procedure is safe and efficacious when performed in unstable coronary syndrome patients.

Angina Pectoris↗
PubMed1999

Chronic pulmonary paracoccidioidomycosis (South American blastomycosis): high-resolution CT findings in 41 patients.

OBJECTIVE: To assess the pulmonary parenchymal findings on high-resolution CT in 41 patients with the chronic form of paracoccidioidomycosis (South American blastomycosis). SUBJECTS AND METHODS: The study included 41 consecutive patients in whom chronic paracoccidioidomycosis had been proven. All patients underwent high-resolution CT (1-mm collimation, high-spatial-frequency reconstruction algorithm) at 12 equally spaced intervals through the chest. The images were analyzed by two radiologists, and each final decision was reached by consensus. RESULTS: Thirty-eight (93%) of the 41 patients had CT scans with abnormal findings. The findings included interlobular septal thickening in 36 patients (88%), 1-25 mm diameter nodules in 34 (83%), peribronchovascular interstitial thickening in 32 (78%), centrilobular opacities in 26 (63%), intralobular lines in 24 (59%), ground-glass opacities in 14 (34%), cavitation in seven (17%), air-space consolidation in five (12%), traction bronchiectasis in 34 (83%), and paracicatricial emphysema in 28 (68%). In approximately 90% of patients, the abnormalities were bilateral and symmetrical and involved all lung zones. CONCLUSION: High-resolution CT findings of paracoccidioidomycosis consist predominantly of interstitial abnormalities and nodules associated with traction bronchiectasis and paracicatricial emphysema in a bilaterally symmetrical distribution.

Adult↗
PubMed1998

Confirmation that heparin is an alternative means of promoting early reperfusion.

BACKGROUND: New strategies to increase coronary patency rate before primary angioplasty are under discussion. We tested the hypothesis that use of a high dose of a standard heparin bolus could achieve an acceptable rate of re-opening occluded infarct-related arteries thus providing an alternative to chemical thrombolysis before admission of the patient to hospital, and a pretreatment for primary angioplasty. METHODS: Forty-eight patients who presented within 12 h of acute myocardial infarction with ST segment elevation were assigned randomly to groups to receive aspirin (200 mg orally) and high-dose standard heparin 300 U/kg as an intravenous bolus (n = 25), or aspirin and placebo bolus (n = 23). Thereafter, all patients underwent coronary arteriography to assess their suitability for primary angioplasty. RESULTS: The high-dose heparin group had greater patency rate (Thrombolysis in Myocardial Infarction grade 2 or 3 flow in the infarct-related artery) than the placebo group (52% compared with 13%, P = 0.006). Hemorrhages related to the puncture site that required blood transfusion occurred in two of 25 and in one of 23 patients in the high-dose heparin and placebo groups, respectively. CONCLUSION: Our study suggests that high-dose standard heparin does have a thrombolytic action when administered as an intravenous bolus.

Aged↗
PubMed1998

Mitochondrial encephalomyopathy and hypoparathyroidism associated with a duplication and a deletion of mitochondrial deoxyribonucleic acid.

Diabetes mellitus is the most frequent endocrinopathy associated with mitochondrial disorders, particularly in patients with duplications of mitochondrial DNA (mtDNA). Although hypoparathyroidism has also been described in mitochondrial diseases, there have been few molecular studies in these cases, most of which identified the presence of single mtDNA deletions in the patients' tissues. We studied muscle DNA of a 12-yr-old patient with incomplete Kearns-Sayre syndrome and hypoparathyroidism. Southern analysis showed that muscle DNA contained three populations of mtDNA: wild type (26%), deleted (65%), and duplicated (9%). To determine the sequence of the breakpoint region from deleted and duplicated mtDNA independently, we isolated the deleted and duplicated mtDNA by gel fractionation of a PstI-digested total DNA. The breakpoint was located at mtDNA positions 5788 and 15,448 for both duplicated and deleted molecules. Our study reinforces the concept that endocrinopathies other than diabetes can be associated with a duplication of mtDNA and gives additional support to the hypothesis that the duplication and deletion of mtDNA are generated from the same recombination event.

Base Sequence↗
PubMed1996

Possible modulatory role of non-activated lymphocytes on insulin secretion.

In order to study the probable physiological role of non-activated lymphocytes on islet B-cells, we incubated and perfused rat pancreatic islets in the presence of low (2.8 mM) and high (16.7 mM) glucose concentrations after pre-exposure for 60 min to rat lymphocytes or to substances secreted by lymphocytes. Insulin secretion and 86Rb+, 45Ca2+ and [3H]-phosphoinositide metabolite fluxes were lower compared to controls when islets were pre-exposed to lymphocytes but were not different when islets were pre-exposed to substances secreted by lymphocytes. These alterations in isotope flux suggest that, when lymphocytes and islets are in contact, closure of potassium channels and a paradoxical effect of glucose load on insulin release occur in the presence of low glucose concentrations. The alterations observed are probably due to a swift and direct action of lymphocyte secretion perhaps induced by a direct of islet cells.

Animals↗
PubMed1995

[Apomorphine: an alternative in the control of motor fluctuations in Parkinson's disease].

Levodopa-induced motor fluctuations (MF) is a disabling complication of Parkinson's disease (PD) and is usually refractory to conventional treatment. Apomorphine, a dopamine agonist with affinity for both D1 and D2 receptors, has been emerged as an useful alternative in the management of MF of PD. The frequency of nausea and vomiting prevented its use in the past, but the simultaneous administration of domperidone has proved to be able to control these side effects. Although apomorphine has been successfully used to control levodopa-induced MF in other countries, it has not been considered in the management of PD in Brazil. We report here our initial experience with subcutaneous injections of apomorphine combined to oral domperidone. We administered apomorphine in doses ranging from 1.5 to 3 mg in four PD patients with MF of our outpatient clinic. All the doses administered switched the "off" state to a motor response qualitatively similar to what is seen in the "on" phase induced by levodopa, including the occurrence of dyskinesia. The latency to turn "on" after apomorphine ranged from 7 to 30 minutes and the duration of the response ranged from 60 to 85 minutes. We observed yawning in all four patients, labial paresthesia in one patient and an inspecific unpleasant sensation in another patient. These side effects were not significant in our four patients. Our data show that the use of apomorphine adds a reliable and effective strategy in the management of MF of PD patients.

Antiparkinson Agents↗
PubMed1995

[Levodopa-induced dyskinesia in 176 patients with Parkinson's disease].

Dyskinesias are frequently observed in parkinsonian patients during levodopa treatment. The occurrence of these movement disorders usually makes the therapeutic management of the patients very difficult. The clinical characteristics of 176 patients with dyskinesias were retrospectively studied. Dyskinesias occurred, on average, after 6.2 years of duration of Parkinson's disease and after 4.2 years on treatment with levodopa. Patients were more likely to have dyskinesias during more advanced stages (measured by Hoehn and Yahr scale). Peak of dose and square wave were the types of dyskinesia more frequently described and were associated with choreic movements in most cases. Dystonia occurred in 40% of the cases and was predominant in end of dose and diphasic dyskinesias. Thirty-five percent of dystonia cases presented as "early morning dystonia". Chorea was the most frequent involuntary movement and mostly generalized. Dystonia was most commonly described in lower limbs. Orofacial dyskinesia, when occurred alone, was more frequently seen in old rather than young patients. When dyskinesia was unilateral it was more likely to occur in the side where Parkinson's disease was more severe.

Adolescent↗
PubMed1994

[Postural tremor and dystonia. Clinical aspects and physiopathological considerations].

The coexistence of tremor and dystonia is usually seen but there is not a satisfactory explanation for it. Some consider that essential tremor (ET) and idiopathic dystonia (ID) may be genetically linked. To clarify this relationship we evaluated the frequency of postural hand tremor in ID and symptomatic dystonia (SD) patients. We studied the records of patients with dystonia seen in our Movement Disorders Unit. ID was considered when there was no other neurological abnormality in the examination aside from dystonia, normal laboratorial tests and neuroimaging related to dystonia, and a negative past history for any known cause for it, except for genetic predisposition. We analyzed the clinical characteristics of dystonia and the occurrence of postural tremor. We collected 185 patients, being 120 with ID and 65 with SD. Tremor was seen in 27 (22.5%) of ID and 14 (21.5%) of SD. Tremor was present in either focal, segmental or generalized dystonia in both ID and SD. Family history for ET was absent in all patients. The similar frequency of tremor in ID and SD patients suggests that the pathophysiologic derangement resulting in dystonia can favor the development of tremor.

Adult↗