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Biomedical subjects

L M Oliveira

Publications and source records attributed to L M Oliveira.

At least 19 recordsLinked to original sources
PubMed2002

Isokinetic evaluation of the knee in patients with rheumatoid arthritis.

OBJECTIVES: Rheumatoid arthritis is a chronic inflammatory disease with a clinical picture of arthritis, muscle hypotrophy, loss of range of motion, loss of strength and disability. The objective of this study was to evaluate knees of patients with rheumatoid arthritis using an isokinetic dynamometer. METHODS: Fifty patients with a diagnosis of rheumatoid arthritis and 50 control subjects were evaluated using an isokinetic dynamometer (Cybex 6.000) regarding the following parameters: peak torque, peak torque angle, power, total work, peak torque acceleration time, set total work, torque acceleration energy ('explosion') and endurance. Comparisons between rheumatoid arthritis and the control group, left side versus right side, flexors and extensors and the proportion between flexors and extensors were made. The subjects were also evaluated through the Health Assessment Questionnaire, visual and analogical scale of pain, EPM-ROM and goniometry of the knee. RESULTS: The results showed that patients with rheumatoid arthritis have less strength than the control group (P < 0.05); the extensors are stronger than the flexors (P < 0.05); no significant differences between the right and the left knee for rheumatoid arthritis and the control group were observed and the proportion between flexors and extensors is the same in both groups. We concluded that regarding the isokinetic parameters, the knees of subjects with rheumatoid arthritis are different from normal knees with decreased strength parameters, maintaining the proportion between flexors and extensors with a global loss of strength in the segment, excluding the high speeds in some of the parameters.

Adult↗
PubMed2001

Behavioral properties of the trigeminal somatosensory system in rats performing whisker-dependent tactile discriminations.

To address several fundamental questions regarding how multiwhisker tactile stimuli are integrated and processed by the trigeminal somatosensory system, a novel behavioral task was developed that required rats to discriminate the width of either a wide or narrow aperture using only their large mystacial vibrissae. Rats quickly acquired this task and could accurately discriminate between apertures of very similar width. Accurate discriminations required a large number of intact facial whiskers. Systematic removal of individual whiskers caused a decrease in performance that was directly proportional to the number of whiskers removed, indicating that tactile information from multiple whiskers is integrated as rats gauge aperture width. In different groups of rats, different sets of whiskers were removed in patterns that preferentially left whisker rows or whisker arcs intact. These different whisker removals caused similar decreases in performance, indicating that individual whiskers within the vibrissal array are functionally equivalent during performance of this task. Lesions of the barrel cortex abolished the ability of rats to discriminate, demonstrating that this region is critically involved in this tactile behavior. Interestingly, sectioning the facial nerve, which abolished whisker movements, did not affect the ability to perform accurate discriminations, indicating that active whisker movements are not necessary for accurate performance of the task. Collectively, these results indicate that the trigeminal somatosensory system forms internal representations of external stimuli (in this case, aperture width) by integrating tactile input from many functionally equivalent facial whiskers and that the vibrissal array can function as a fine-grained distance detector without active whisker movements.

Afferent Pathways↗
PubMed2001

Malnutrition and environmental stimulation in rats: interpeak intervals of the brainstem auditory evoked potentials.

The aim of this study was to investigate the effects of malnutrition, nutritional recovery, environmental stimulation and click intensity on the interpeak intervals of the waves of the Brainstem Auditory Evoked Potentials (BAEPs). The animals were divided into Well-nourished (W) and Malnourished (M) groups. At weaning, half of the M rats were submitted to nutritional recovery (R) until the test day. These groups were further subdivided into Stimulated (S) and Non-stimulated (N) rats. The BAEPs interpeak intervals I-III, I-IV and III-IV were analysed in independent groups of rats on the 18th, 22nd, 32nd and 42nd days of age. During the lactation period, stimulated rats presented shorter I-III, I-IV and III-IV interpeak intervals than Non-stimulated animals. This analysis also indicated a diet x stimulation x age interaction during the lactation period. The WN and MN groups showed a longer I-IV interval than the WS and MS groups, respectively, on the 18th and 22nd day of age, and the MN group also presented a longer I-IV interpeak interval than the WN group on the 22nd day of age. During the post-lactation period, stimulated animals showed shorter I-III and I-IV intervals than non-stimulated rats. Post hoc analysis indicated longer I-III and I-IV interpeak intervals in the MN than in the WN, RN and MS groups. Additionally, malnourished animals showed longer I-III and I-IV intervals than well-nourished and recovered rats when exposed to clicks of 90, 80 or 70 dB intensity. Malnutrition resulted in a delay of normal development of the brainstem auditory pathway indicated by the increases in the interpeak intervals of BAEPs waves, and environmental stimulation reduced these intervals, promoting faster nervous impulse transmission.

Acoustic Stimulation↗
PubMed2001

Prevalence, phenotypic spectrum, and modes of inheritance of gonadotropin-releasing hormone receptor mutations in idiopathic hypogonadotropic hypogonadism.

Mutations in the GnRH receptor (GNRHR) have been described as a cause of reproductive failure in a subset of patients with idiopathic hypogonadotropic hypogonadism (IHH). Given the apparent rarity of these mutations, we set out to determine the frequency and distribution of GNRHR mutations in a heterogeneous population of patients with IHH who were well characterized with respect to diagnosis, phenotype, and mode of inheritance and to define their distribution within the receptor protein. One hundred and eight probands with IHH were screened for mutations in the coding sequence of GNRHR. Forty-eight of the 108 patients had a normal sense of smell, whereas the remaining 60 had anosmia or hyposmia (Kallmann syndrome). Exon segments in the GNRHR were screened for mutations using temperature gradient gel electrophoresis, and all mutations were confirmed by direct sequencing. Five unrelated probands (3 men and 2 women), all normosmic, were documented to have changes in the coding sequence of the GNRHR. Two of these probands were from a subgroup of 5 kindreds consistent with a recessive mode of inheritance, establishing a GNRHR mutation frequency of 2 of 5 (40%) in patients with normosmic, autosomal recessive IHH. The remaining 3 probands with GNRHR mutations were from a subgroup of 18 patients without evidence of familial involvement, indicating a prevalence of 3 of 18 (16.7%) in patients with sporadic IHH and a normal sense of smell. Among the five individuals bearing GNRHR mutations, a broad spectrum of phenotypes was noted, including testicular sizes in the male that varied from prepubertal to the normal adult male range. Three probands had compound heterozygous mutations, and two had homozygous mutations. Of the eight DNA sequence changes identified, four were novel: Thr(32)Ile, Cys(200)Tyr, Leu(266)Arg, and Cys(279)TYR: COS-7 cells transiently transfected with complementary DNAs encoding the human GNRHR containing each of these four novel mutations failed to respond to GnRH agonist stimulation. We conclude that 1) the spectrum of phenotypes in patients with GNRHR mutations is much broader than originally anticipated; 2) the frequency of GNRHR mutations may be more common than previously appreciated in familial cases of normosmic IHH and infrequent in sporadic cases; and 3) functional mutations of the GNRHR are distributed widely throughout the protein.

Amino Acid Sequence↗
PubMed2001

The importance of autosomal genes in Kallmann syndrome: genotype-phenotype correlations and neuroendocrine characteristics.

Kallmann syndrome (KS) consists of congenital, isolated, idiopathic hypogonadotropic hypogonadism (IHH) and anosmia. The gene responsible for the X-linked form of KS, KAL, encodes a protein, anosmin, that plays a key role in the migration of GnRH neurons and olfactory nerves to the hypothalamus. In addition to X-linked pedigrees, autosomal dominant and recessive kindreds with KS have been reported. The relative importance of these autosomal vs. X-linked genes in producing KS, and the frequency of KAL mutations, are currently unknown because these are rare disorders and large series are unusual. We examined 101 individuals with IHH (+/- anosmia) and their families to determine their modes of inheritance, incidence of mutations in the coding sequence of KAL, genotype-phenotype correlations, and [in a subset (n = 38)] their neuroendocrine phenotype. Of the 101 patients, 59 had true KS (IHH + anosmia/hyposmia); whereas, in the remaining 42, no anosmia was evident in the patients or their families. Of the 59 KS patients, 21 were familial, whereas 38 were sporadic cases. Mutations in the coding sequence of KAL were identified in only 3 of 21 familial cases (14%) and 4 of 38 (11%) of the sporadic cases. Of the X-linked cases confirmed by mutational analysis, only 1 of 3 pedigrees appeared X-linked by inspection whereas the other 2 contained only affected brothers. Female members of known KAL mutation families (n = 3) exhibited no reproductive phenotype and were not anosmic, whereas families with anosmic women (n = 3) were not found to carry mutations in KAL. Mutations were uniformly absent in nonanosmic IHH probands (n = 42), as well as in families with both anosmic and nonanosmic members (n = 2). Overall, 4 novel mutations were identified (C172R, R191x, R457x, and delC@L600). With respect to neuroendocrine phenotype, KS men with documented KAL mutations (n = 8) had completely apulsatile LH secretion, whereas those with autosomal modes of inheritance demonstrated a more variable spectrum with evidence of enfeebled (but present) GnRH-induced LH pulses. Our conclusions are: 1) Confirmed mutations in the coding sequence of the KAL gene occur in the minority of KS cases, i.e. only 14% of familial and 11% of sporadic cases; 2) The majority of familial (and presumably sporadic) cases of KS are caused by defects in at least two autosomal genes that are currently unknown; 3) Obligate female carriers in families with KAL mutations have no discernible phenotype; 4) KAL mutations are uniformly absent in patients with either normosmic IHH or in families with both anosmic and nonanosmic individuals; and 5) Patients with KAL mutations have apulsatile LH secretion consistent with a complete absence of GnRH migration of GnRH cells into the hypothalamus, whereas evidence of present (but enfeebled) GnRH-induced LH pulses may be present in autosomal KS cases. Taken together, these findings suggest that autosomal genes account for the majority of familial cases of KS, and that unique neuroendocrine phenotypes consistent with some GnRH neuronal migration may exist in these patients.

Adult↗
PubMed2001

[Changes in regional wall contractility induced by effort in women with normal coronary angiography --report of a clinical case].

The diagnosis of coronary artery disease in women has been thought to be more difficult than in men, owing to the lower overall prevalence of disease in women, as well as more subtle clinical presentations and unspecific changes in ST segment. The authors report a clinical case of a 61-year old woman, with low cardiovascular risk and history of atypical chest pain and a positive treadmill exercise test on the inferior leads. She did an exercise echocardiogram that revealed severe hypokinesis on the anterior wall and septum with late normalization. The patient was submitted to a coronary angiography that revealed normal arteries. An echocardiogram with hyperventilation was later performed and showed the same ischemic changes as exercise did, on the inferior leads but no regional wall motions abnormalities occurred. The patient is currently asymptomatic under calcium antagonist treatment.

Coronary Angiography↗
PubMed2000

Genetics of hypogonadotropic hypogonadism.

Determining the physiologic influences that modulate GnRH secretion, the prime initiator of reproductive function in the human, is fundamental not only to our understanding of the rare condition of congenital idiopathic hypogonadotropic hypogonadism (IHH), but also common disorders such as constitutional delay of puberty and hypothalamic amenorrhea. IHH is characterized by low levels of sex steroids and gonadotropins, normal findings on radiographic imaging of the hypothalamic-pituitary regions, and normal baseline and reserve testing of the remainder of the hypothalamic-pituitary axes. Failure of the normal pattern of episodic GnRH secretion results in delay of puberty and infertility. IHH is characterized by rich clinical and genetic heterogeneity, variable modes of inheritance, and association with other anomalies. To date, 4 genes have been identified as causes of IHH in the human; KAL [the gene for X-linked Kallmann syndrome (IHH and anosmia)], DAX1 [the gene for X-linked adrenal hypoplasia congenita (IHH and adrenal insufficiency)], GNRHR (the GnRH receptor), and PC1 (the gene for prohormone convertase 1, causing a syndrome of IHH and defects in prohormone processing). As these mutations account for less than 20% of all IHH cases, discovery of additional gene mutations will continue to advance our understanding of this intriguing syndrome.

Aspartic Acid Endopeptidases↗
PubMed2000

Gamma dose response of synthetic A-type carbonated apatite in comparison with the response of tooth enamel.

Synthetic A-type carbonated apatite samples were irradiated at room temperature with 60Co gamma rays. Their ESR spectra consist of the lines of CO2- and CO3- radicals of orthorhombic and axial symmetry. The measurements carried out immediately after sample irradiation showed that CO2- species are produced by decomposition of CO3- radicals. Intensity of the CO2- lines in the synthetic and enamel samples increases during the first 400 and 200 h after irradiation, respectively. The dependence of the EPR signal on the dose varies with carbonate content of the sample. The dose response curve for tooth enamel is steeper for the synthetic material.

Apatites↗
PubMed2000

Cardiac rupture during exercise stress echocardiography: a case report.

Stress echocardiography is widely used in the evaluation of coronary artery disease. Dobutamine stress echocardiography has been the preferred method, but many centers have adopted exercise stress echocardiography, which can visualize myocardial motion during physiologic stress testing. The complications of this method in the post-myocardial infarction period are the same as those identified in conventional exercise testing. We report a case of myocardial rupture in the postinfarction period during exercise stress echocardiography.

Aged↗
PubMed2000

Successful use of pulsatile gonadotropin-releasing hormone (GnRH) for ovulation induction and pregnancy in a patient with GnRH receptor mutations.

GnRH receptor mutations have recently been identified in a small number of familial cases of nonanosmic hypogonadotropic hypogonadism. In the present report we studied a kindred in which two sisters with primary amenorrhea were affected with GnRH deficiency due to a compound heterozygote mutation (Gln(106)Arg, Arg(262)Gln) and performed extensive phenotyping studies. Baseline patterns of gonadotropin secretion and gonadotropin responsiveness to exogenous pulsatile GnRH were examined in the proband. Low amplitude pulses of both LH and free alpha-subunit (FAS) were detected during 24 h of every 10 min blood sampling. The proband then received exogenous pulsatile GnRH i.v. for ovulation induction, and daily blood samples for gonadotropins and sex steroids were monitored. At the conventional GnRH replacement dose for women with hypogonadotropic hypogonadism (75 ng/kg), no follicular development occurred. At a GnRH dose of 100 ng/kg, the level and pattern of gonadotropin secretion more closely mimicked the follicular phase of normal women; a single dominant follicle was recruited, and an endogenous LH surge was elicited. However, the luteal phase was inadequate, as assessed by progesterone levels. At a GnRH dose of 250 ng/kg, the gonadotropin and sex steroid dynamics reproduced those of normal ovulatory women in both the follicular and luteal phases, and the proband conceived. The FAS responses to both conventional and high dose GnRH were within the normal range. The following conclusions were made: 1) Increased doses of GnRH may be used effectively for ovulation induction in some patients with GnRH receptor mutations. 2) Higher doses of GnRH are required for normal luteal phase dynamics than for normal follicular phase function. 3) Hypersecretion of FAS in response to exogenous GnRH, which is a feature of congenital hypogonadotropic hypogonadism, was not seen in this patient with a GnRH receptor mutation.

Adolescent↗
PubMed2000

[Plasma total anti-oxidant status in young survivors of myocardial infarction].

UNLABELLED: Free oxygen radicals are involved in the endothelial lesion process which leads to the formation of the atheroma plaque and thrombosis. There is some evidence that antioxidant therapy may be beneficial in coronary heart disease prevention. Our objective was to study the plasma total anti-oxidant status in young survivors of acute myocardial infarction. POPULATION: 23 patients, mean age 35.2 years (22-40) admitted for acute myocardial infarction from January 1995 to June 1998 (20 males). RISK FACTORS: Tobacco smoking 22/23, systemic arterial hypertension 4/23, hypercholesterolemia 17/23, positive family history for coronary heart disease 5 patients, previous history of angina 4 patients, none of these patients had diabetes mellitus. The location of the infarct was anterior in 12 patients, inferior in 10 patients and non-Q wave in one patient. Blood samples were drawn after overnight fasting and the plasma total antioxidant status (TAS) was determined by a colorymethric method (Trolox equivalent). The mean time elapsed since the acute myocardial infarction until sample collection was 16.5 +/- 10.7 months. RESULTS: 18 patients had low TAS values, mean 1.23 +/- 0.11 mmol/L (below the reference values: 1.3-1.77 mmol/L). CONCLUSIONS: In this group of patients, the plasma total antioxidant capacity was globally decreased, which may constitute a risk factor for coronary heart disease.

Adult↗
PubMed1999

Effects of apolipoprotein E genotype on blood lipid composition and membrane platelet fluidity in Alzheimer's disease.

The blood lipid composition (plasma, platelets and leukocytes), platelet membrane fluidity, apolipoproteins A and B in the plasma of AD patients and control subjects with distinct Apo E genotypes were investigated. No significant differences were found between the Apo E genotype and the cholesterol, phospholipids, triglycerides and Apo B levels in the plasma; cholesterol and phospholipids levels in platelet and leukocyte membranes; and platelet membrane fluidity of AD and control groups. However, the phospholipid levels in the leukocyte membranes of the control subgroup with the genotypes epsilon3/epsilon3 and epsilon3/epsilon4 and the AD subgroups with the genotypes epsilon2/epsilon3 and epsilon3/epsilon3, epsilon3/epsilon4 and epsilon4/epsilon4 were significantly lower than those observed in the control subgroup with the genotype epsilon2/epsilon3. Moreover, the cholesterol and phospholipid levels in the platelet membranes of the AD subgroup with the epsilon2 allele were significantly higher than those in the AD subgroup without the epsilon2 allele and the control subgroups with and without the epsilon2 allele. A strong correlation was found between cholesterol and phospholipids levels in the platelet membranes of the AD and control subgroups without the epsilon2 allele, but the residual cholesterol level in the platelet membranes of the AD subgroup was twice that observed in the control subgroup. Furthermore, the Apo A levels in the plasma of the AD subgroup with the epsilon3 allele were significantly lower than those observed in the AD subgroup without the epsilon3 allele and the control subgroup with the epsilon3 allele. The results are discussed in terms of involvement of lipid metabolism in the etiopathogenesis of AD.

Adult↗
PubMed1999

Diagnosing dementia and normal aging: clinical relevance of brain ratios and cognitive performance in a Brazilian sample.

The main objective of the present study was to evaluate the diagnostic value (clinical application) of brain measures and cognitive function. Alzheimer and multi-infarct patients (N = 30) and normal subjects over the age of 50 (N = 40) were submitted to a medical, neurological and cognitive investigation. The cognitive tests applied were Mini-Mental, word span, digit span, logical memory, spatial recognition span, Boston naming test, praxis, and calculation tests. The brain ratios calculated were the ventricle-brain, bifrontal, bicaudate, third ventricle, and suprasellar cistern measures. These data were obtained from a brain computer tomography scan, and the cutoff values from receiver operating characteristic curves. We analyzed the diagnostic parameters provided by these ratios and compared them to those obtained by cognitive evaluation. The sensitivity and specificity of cognitive tests were higher than brain measures, although dementia patients presented higher ratios, showing poorer cognitive performances than normal individuals. Normal controls over the age of 70 presented higher measures than younger groups, but similar cognitive performance. We found diffuse losses of tissue from the central nervous system related to distribution of cerebrospinal fluid in dementia patients. The likelihood of case identification by functional impairment was higher than when changes of the structure of the central nervous system were used. Cognitive evaluation still seems to be the best method to screen individuals from the community, especially for developing countries, where the cost of brain imaging precludes its use for screening and initial assessment of dementia.

Age Factors↗
PubMed1999

Apolipoprotein E genotype has no effect on the free intracellular Ca2+ concentration of platelets from Alzheimer's disease patients.

The free intracellular Ca2+ concentration [Ca2+]i of platelets was investigated in Alzheimer's disease (AD) patients and age-matched control subjects with distinct Apo E genotypes. No significant differences were found between the Apo E genotype and the [Ca2+]i levels of platelets (basal and alpha-thrombin stimulated) from AD patients and age-matched control subjects, suggesting that [Ca2+]i homeostasis of platelets from AD patients is independent of the Apo E genotype. The results are discussed in terms of involvement of Apo E and [Ca2+]i changes in the etiopathogenesis of AD.

Adult↗
PubMed1999

Influence of apolipoprotein E genotype on blood redox status of Alzheimer's disease patients.

The blood redox status of probable Alzheimer's Disease (AD) patients and control subjects with distinct Apo E genotypes was investigated. It was assessed by measuring the levels of hydroperoxides (MDA) in plasma and erythrocytes, the levels of the antioxidant defense system (enzymatic and non-enzymatic) in plasma, erythrocytes, platelets and leukocytes, the activities of catechol-O-methyltransferase (COMT) in erythrocytes and monoamine oxidase-B (MAO-B) in platelets and also the activity of the mitochondrial respiratory chain in leukocytes. No significant differences were found between the Apo E genotype and MDA, uric acid, vitamin E and reduced-glutathione (GSH) levels in plasma; MDA, vitamin E, GSH, superoxide-dismutase (SOD), glutathione-peroxidase (GSH-Px) and COMT levels in erythrocytes; vitamin E levels in the platelets of AD patients and control subjects. However, the uric acid levels in plasma and the COMT levels in erythrocytes of AD patients and control subjects with the epsilon4 allele were significantly lower than those observed in control subjects without the epsilon4 allele. Moreover, the duraquinol oxidation level in leukocytes of AD patients with the epsilon4 allele was significantly higher than that in AD patients without the epsilon4 allele and control subjects with and without the epsilon4 allele. The meaning of these results is discussed in terms of involvement of oxidative stress in the etiopathogenesis of AD.

Adult↗
PubMed1999

Pediatric Escola Paulista de Medicina Range of Motion Scale: a reduced joint count scale for general use in juvenile rheumatoid arthritis.

OBJECTIVE: Different instruments are available to measure functional status in juvenile rheumatoid arthritis (JRA); however, none is based on the evaluation of joint range of motion (ROM). We designed and evaluated a ROM scale to be used as a complementary instrument in daily practice with JRA as well as in trials. METHODS: The 10 joint movements of the Pediatric Escola Paulista de Medicina Range of Motion scale (Pediatric EPM-ROM) were derived from 25 initial movements. The selection was based on 2 criteria: (1) consensus among 3 pediatric rheumatologists, one physical therapist, and one occupational therapist; and (2) choice of movements that presented the highest scores in a pilot study involving patients with JRA. The score for each joint ranges from 0 (full movement) to 3 (severe limitation) and the cutoff degrees of motion are, in general, based on the lack of ability to perform some activities of daily living. The test-retest reliability was assessed by administering the scale twice by the same observer, 4 to 10 days apart, always in the morning. The interobserver reliability was evaluated on the same day by 2 independent observers. Cross sectional construct validity was also assessed by correlating the values of some clinical variables with the scores of the Pediatric EPM-ROM scale. RESULTS: The instrument was applied to 34 patients with JRA, 11 systemic, 11 polyarticular, and 12 pauciarticular. The mean EPM-ROM score was 0.57 (SD 0.54, min 0, max 2.05). The test-retest and interobserver correlation coefficients were 0.96 and 0.98, respectively. The Pearson correlation coefficients comparing scores of the Pediatric EPM-ROM scale and other variables were satisfactory: Childhood Health Assessment Questionnaire, r=0.55 (p<0.001); American College of Rheumatology global functional class, r=0.56 (p<0.001); and number of limited joints, r=0.65 (p<0.001). CONCLUSION: Our results provide evidence that the Pediatric EPM-ROM scale is a valid instrument to measure joint ROM in JRA.

Adolescent↗
PubMed1998

Simultaneous encoding of tactile information by three primate cortical areas.

We used simultaneous multi-site neural ensemble recordings to investigate the representation of tactile information in three areas of the primate somatosensory cortex (areas 3b, SII and 2). Small neural ensembles (30-40 neurons) of broadly tuned somatosensory neurons were able to identify correctly the location of a single tactile stimulus on a single trial, almost simultaneously. Furthermore, each of these cortical areas could use different combinations of encoding strategies, such as mean firing rate (areas 3b and 2) or temporal patterns of ensemble firing (area SII), to represent the location of a tactile stimulus. Based on these results, we propose that ensembles of broadly tuned neurons, located in three distinct areas of the primate somatosensory cortex, obtain information about the location of a tactile stimulus almost concurrently.

Action Potentials↗