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Biomedical subjects

L C Oliveira

Publications and source records attributed to L C Oliveira.

11 recordsLinked to original sources
PubMed2006

Peptides of arachnid venoms with insecticidal activity targeting sodium channels.

Arachnids have a venom apparatus and secrete a complex chemical mixture of low molecular mass organic molecules, enzymes and polypeptide neurotoxins designed to paralyze or kill their prey. Most of these toxins are specific for membrane voltage-gated sodium channels, although some may also target calcium or potassium channels and other membrane receptors. Scorpions and spiders have provided the greatest number of the neurotoxins studied so far, for which, a good number of primary and 3D structures have been obtained. Structural features, comprising a folding that determines a similar spatial distribution of charged and hydrophobic side chains of specific amino acids, are strikingly common among the toxins from spider and scorpion venoms. Such similarities are, in turn, the key feature to target and bind these proteins to ionic channels. The search for new insecticidal compounds, as well as the study of their modes of action, constitutes a current approach to rationally design novel insecticides. This goal tends to be more relevant if the resistance to the conventional chemical products is considered. A promising alternative seems to be the biotechnological approach using toxin-expressing recombinant baculovirus. Spider and scorpion toxins having insecticidal activity are reviewed here considering their structures, toxicities and action mechanisms in sodium channels of excitable membranes.

Animals↗
PubMed2003

Butyrylcholinesterase and obesity in individuals with the CHE2 C5+ and CHE2 C5- phenotypes.

OBJECTIVE: To investigate the association between butyrylcholinesterase (BChE) activities (total and band specific) and body mass index (BMI) in obese and nonobese individuals, considering other variables (anthropometric, biochemical and hormonal) and the leanness process. SUBJECTS: Obese (BMI> or =30 kg/m(2); N=181) and nonobese individuals (N=265), classified according to the CHE2 locus phenotypes, with the obese patients being followed-up when submitted to a weight-loss program. MEASUREMENTS: Anthropometric (weight, height, BMI, waist, waist/hip ratio-WHR, triceps and subscapular skinfolds, percentage of body fat and arterial pressures), hormonal (insulin, estradiol-E(2), triiodothyronine-T(3) and thyroxine-T(4)) and biochemical (glucose, total cholesterol, HDL-C, triglycerides, uric acid, urea, creatinine, sodium, potassium and BChE activities) variables. RESULTS: Although obese CHE2 C5- individuals presented higher mean BChE activities than their CHE2 C5- controls and diminished mean activities with leanness, similar comparisons did not show any difference in the CHE2 C5+ group. Furthermore, the mean serum potassium values of obese individuals were significantly higher in the CHE2 C5+ than in the CHE2 C5- phenotype. The BChE activities were less related to BMI in obese CHE2 C5- individuals than in their controls. In the CHE2 C5- obese group, significant regression coefficients were found between BChE activity variables and BMI (+), ethnic origin (higher in Euro-Brazilians), sex (higher in males), diastolic pressure (-), triceps skinfold (+), total cholesterol (+), T(3) (+) and E(2) (-). The main findings in the CHE2 C5+ obese group: mean insulin levels decreased with leanness and a significant correlation was detected between the C(5) complex activity and creatinine (+), insulin (-) and WHR (-); a significantly higher frequency of weight loss occurred compared to the CHE2 C5- group. CONCLUSION: In the present study, different relations between obesity and some of the studied variables were found when CHE2 C5+ and CHE2 C5- individuals were compared.

Adolescent↗
PubMed2001

Midline nasal mass in infancy: a nasal glioma case report.

Congenital midline nasal masses are rare anomalies that occur in about one in 20,000-40,000 live births. The most common are dermoid/epidermoid tumors, nasal cerebral heterotopias (nasal gliomas), and nasal encephaloceles; some have an actual or potential central nervous system connection. Nasal gliomas are CNS masses of neurogenic origin which have lost their intracranial connections and present as an obvious external or intranasal mass at birth without associated surgical symptoms. Careful evaluation is required to confirm the diagnosis and appropriate management. The interpretation of CT and MR images can be difficult but is useful in differentiating nasal gliomas from other congenital nasal masses. The presence of a fibrous stalk may be associated with cranial defects and CSF leak. Excisional biopsy allows histopathologic diagnosis and is the definitive treatment. They are benign lesions, and recurrences are rare, so conservative cosmetic surgical techniques should be chosen for gliomas where there is no proven intracranial extension. The authors report an illustrative nasal glioma case in a one-year-old male infant with extranasal and intranasal components, and discuss the therapeutic options.

Biopsy↗
PubMed2001

Association of the CHE2 locus with body mass index and butyrylcholinesterase activity.

The butyrylcholinesterase (BChE; EC 3.1.1.8) activities of two electrophoretic bands of the CHE2 C5+ phenotype--C5 and C(OF) (other forms)--were quantified by densitometry in 100 individuals. The activity data suggested that, in addition to determining C5, the CHE2*C5+ allele also increases the level of other BChE forms. Since the relative activity of C5 showed the highest correlation coefficient with weight when compared with the other BChE activity variables (total, absolute C5, and absolute C(OF)), its median activity level was used for the classification of CHE2 C5+ phenotypes (faint and intense). Mean body mass index (BMI) was compared among the CHE2 locus phenotypes-controlled by sex, age, and ethnic group. It was shown that the intense CHE2 C5+ phenotype presents a significantly lower (p < 0.001) mean BMI (23.2) than the other phenotypes (faint CHE2 C5+ = 25.2; CHE2 C5- = 25.4). It seems that the relative COF activity is positively associated with fat storage, since CHE2 C5- and faint CHE2 C5+ phenotypes showed higher mean BMI than the intense CHE2 C5+ phenotype. Our hypothesis is that the presence of C5 in a relatively high proportion leads to less fat storage.

Adult↗
PubMed2000

Serologic testing for Trypanosoma cruzi: comparison of radioimmunoprecipitation assay with commercially available indirect immunofluorescence assay, indirect hemagglutination assay, and enzyme-linked immunosorbent assay kits.

The radioimmunoprecipitation assay (RIPA) has been used as a confirmatory test in several ongoing and published studies of Trypanosoma cruzi in blood donors in the United States. Despite its use as a confirmatory test, few studies are available comparing RIPA to commercially available serologic test methods. Thus, we compared RIPA with two indirect hemagglutination assays (Biolab Diagnostica SA, São Paulo, Brazil; Hemagen Diagnostics, Inc., Waltham, Mass.) and four different enzyme-linked immunosorbent assays (Abbott Laboratories, Abbott Park, Ill.; Embrabio, São Paulo, Brazil; Organon Teknika, São Paulo, Brazil; and Gull Laboratories, Salt Lake City, Utah) using a panel of 220 serum specimens from Brazilian blood donors with a range of T. cruzi antibody titers as determined by indirect immunofluorescence assay (IFA). A titer of 1:20 was used as the baseline for seropositivity. All IFA-negative serum specimens (n = 19) were nonreactive on all tests. At a titer of 1:20 (n = 9), reactivity rates varied considerably among the tests, with only the RIPA and the Organon and Gull assays identifying reactive specimens. For specimens at a 1:40 titer (n = 35), most assays identified at least 32 of 35 (91%) specimens as reactive, but the Biolab assay only identified 24 (69%). At higher titers (1:80, n = 56; 1:160, n = 101) the assays were comparable, with the exception of the Biolab assay, demonstrating rates of agreement with IFA of >/=98%. Overall, when compared with several other test formats, RIPA demonstrated equivalent or superior rates of agreement with IFA-positive specimens across all titers examined. In particular, at titers of >1:40, the RIPA compared favorably with other test methods currently in use, supporting its application as a confirmatory test, particularly in a research setting.

Animals↗
PubMed2000

Delay in gallbladder emptying during the perimenopausal period.

A pilot study has ascribed an important role in gallbladder motility and emptying to the perimenopausal period. To assess the effect of this period on gallbladder emptying and cholelithogenesis, 25 women in the perimenopausal period without gallbladder disease were submitted to cholangiography and two ultrasound exams. The time for gallbladder emptying and the presence of cholelithiasis were assessed. All patients presented a delay in gallbladder emptying with no relationship to the pre- or postmenopausal period. This finding was not related to lithogenesis. Gallbladder emptying time is longer during the perimenopausal period.

Adult↗
PubMed1995

Frequency of cholelithiasis in alcoholics.

In order to determine the frequency of biliary lithiasis in alcoholic patients without signs of hepatic cirrhosis, we submitted 106 male alcoholics (mean age, 42.2 +/- 11.2 years) to ultrasound examination of the biliary system. Cholelithiasis was present in 6 (5.6%). We did not observe any association between the quantity of ethanol consumed and/or the time of consumption and the presence of cholelithiasis. There was no significant difference between the frequency of cholelithiasis in these patients and that found in autopsies carried out on 716 male patients (6%) at the Hospital de Clínicas, Universidade Federal de Uberlândia, during the period 1982 to 1993. Thus, we conclude that in the cases we examined, alcoholism did not represent a risk factor for biliary lithogenesis.

Adult↗
PubMed1993

Blood glucose and insulin response to intravenous glucose by patients with chronic Chagas' disease and alcoholism.

Blood glucose and insulin responses to intravenous glucose 500 mg/kg in a group of alcoholic chagasic patients (Group I, N = 15) were assessed and compared to those of a group of patients with Chagas' disease without alcoholism (Group II, N = 16), a group of alcoholics without Chagas' disease (Group III, N = 22), and a group of non-alcoholics without Chagas' disease (Group IV, N = 15). Determinations of serum glucose and insulin were done under fasting conditions, 5 and 10 min after the injection of 50% glucose. There was no difference in mean serum glucose levels between groups. Mean serum insulin levels at times 5 and 10 min and for the total integrated response were lower (P < 0.05) in Groups I and II as compared to Group IV; at time 10 min the mean was lower (P < 0.05) in Group III as compared to Group IV. There was a nonsignificant trend for a lower insulinemic response in Group I as compared to Group II. These data suggest denervation of or injury to pancreatic B cell by Chagas' disease.

Adult↗
PubMed1982

A case of acute poisoning by methyl demeton in a female 5 months pregnant.

During the last decade the number of poisonings by pesticides in Portugal has been steadily rising. Out of 140 patients treated in our Intensive Care Unit (I.C.U.), 86 were male and 54 were female, one of whom was 5 months pregnant. Besides all the care and surveillance required by every case of acute poisoning, pregnant females raise particular problems. Four months later, she gave birth to a normal child. Its follow-up has shown a normal morpho-physiological and psycho-motor development.

Adult↗