Mário José dos Santos Pereira

Schistosoma mansoni Sambon, 1907: morphometric differences between adult worms from sympatric rodent and human isolates

A computer software for image analysis (IMAGE PRO PLUS, MEDIA CYBERNETICS) was utilized in male and females adult worms, aiming the morphological characterization of Schistosoma mansoni samples isolated from a slyvatic rodent, Nectomys squamipes, and humans in Sumidouro, Rio de Janeiro, Brazil and recovered from Mus musculus C3H/He. The following characters for maless testicular lobes were analyzed: number, area, density, larger and smaller diameter, longer and shorter axis and perimeter and extension; for females: area, longer and shorter axis, larger and smaller diameter and perimeter of the eggs and spine; oral and ventral suckers area and distance between them in both sex were determined. By the analysis of variance (one way ANOVA) significant differences (p < 0.05) were observed in all studied characters, except for the density of testicular lobes. Significant differences (p < 0.05) were detected for all characters in the female worms. Data ratify that sympatric isolates present phenotypic differences and the adult female characters are useful for the proper identification of S. mansoni isolates.

Long-term effects of overfeeding during lactation on insulin secretion — the role of GLUT-2

Overnutrition during critical developmental periods is believed to be a risk factor for the emergence of metabolic disorders in adulthood. The present study investigated the effects of pups overfeeding during lactation on offsprings insulin secretion. To study the consequences of overnutrition early in life in rats, litter size reduction has been shown to be an appropriate experimental model. To induce early postnatal overnutrition, litter size was reduced to three pups per litter at the third day following birth [overfed group (OG)]. In the control group (CG), the litter size was adjusted to 10 pups per litter. Metabolic parameters and glucose-stimulated insulin secretion were assessed. OG pups ingested more milk at 10 and 21 days and had an augmented food intake at 1 year compared to the CG. Consistently, body weight, body fat, and fasting plasma levels of insulin were higher in 1-year-old OG rats. In addition, OG rats exhibited enhanced insulin secretion, accompanied by elevated content of GLUT-2 in pancreatic islets compared to CG. These findings indicate that early postnatal overnutrition during a critical developmental period in life may program permanent alterations in glucose-stimulated insulin secretion.

Effects of experimental hypothyroidism on myelin sheath structural organization

A previous study using the 2′3′cyclic nucleotide 3′phosphodiesterase (CNPase), an oligodendroglial marker that also stain ensheathed fibers, showed a decrease in the number of immunoreactive fibers and a change in the pattern of CNPase immunoreactivity (CNPase+) in hypothyroid animals. CNPase+ fibers, in mature hypothyroid animals, showed a continuous pattern of staining in contrast with a discontinuous one in controls. As CNPase, in adult animals, can be found only in regions in which oligodendrocyte cytoplasm remains as internal, external and paranodal loops, it was suggested that the reduction of thyroid hormone levels leads to a failure in myelin compaction. Previous data showed a higher frequency of some abnormalities in myelin sheath as multiple cytoplasmic loops and redundant myelin profiles in mutant animals that present a failure in myelin compaction. The increase in the frequency of these abnormalities (multiple internal and external loops and redundant myelin) indicates a failure in the interrelations between the axons and the oligodendroglial processes. To verify if the thyroid hormone deficiency during CNS development disturbs these interrelations, we evaluated the frequency of the morphological abnormalities (multiple internal and external loops and redundant myelin) in myelin sheath of corpus callosum (cc) in experimental hypothyroidism. Randomic fields were kept by electron microscopy and the analysis of the frequency of morphological abnormalities showed a significant difference in hypothyroid animals at 60-day-old (PND60), with no significant differences at 90-day-old (PND90) animals. The frequency of multiple internal loops is higher in hypothyroid animals at PND60 that indicates a disturbance in the wrapping by the oligodendroglial process. These findings showed that thyroid hormone might modulate the axon-oligodendroglial relationships that are important for the adequate temporal sequence of events that occur during myelinogenesis, with possible consequences on myelin compaction.

Bioavailability of the sodium pertechnetate and morphometry of organs isolated from rats: study of possible pharmacokinetic interactions of a ginkgo biloba extract

Many compounds affect the bioavailability of radiobiocomplexes as radiopharmaceuticals. Ginkgo Biloba extract (EGb) has several effects. The influence of an EGb on the bioavailability of the radiobiocomplex sodium pertechnetate (Na99mTcO4) and on the morphometry of the organs was evaluated. Rats were treated with EGb and Na99mTcO4 was injected. The animals were sacrificed; the radioactivity in the organs was counted. The results showed that EGb altered the Na99mTcO4 bioavailability in the kidneys, liver and duodenum. Morphometric analysis of the organs showed significant alterations (P<0.05), probably caused by metabolites generated by EGb and capable of altering the bioavailability of the Na99mTcO4.

Ultrastructural identification of oligodendrocyte/myelin proteins in corpus callosum of hypothyroid animals.

Thyroid hormone (T3) deficiency impairs the development of the CNS, particularly myelination. We have previously described an increase in the frequency of morphological abnormalities in the central myelin sheath in a hypothyroidism model, which reinforced the hypothesis of a role for T3 in myelin compaction. However, there are no data concerning the cellular distribution of myelin proteins in hypothyroid animals. In the present work, we describe the distribution of 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase (CNPase), myelin basic protein (MBP) and proteolipid protein (PLP) throughout the central myelin sheath of a hypothyroidism model. We used euthyroid and hypothyroid adult rats at 90 days of age. In order to induce hypothyroid status, animals received 0.02% methimazol from the 19th gestation day onwards. After perfusion with a fixative mixture, small pieces of corpus callosum were obtained, dehydrated and embedded in LR White resin. Ultrathin sections were immunoreacted, using specific antibodies revealed by a secondary antibody coupled to colloidal gold particles of 10 nm. Gold particle density per region of myelin sheath for each one of these proteins was obtained. In normal animals, CNPase, PLP and MBP were identified in sites that had already been described in previous studies. In hypothyroid animals, CNPase was identified in the region corresponding to compact lamellae, which normally does not contain this protein, while, in this same region, PLP and MBP immunolabeling were decreased. These results suggest that thyroid hormone deficiency impairs the distribution of the major oligodendrocyte/myelin markers. This effect may justify the reduction in myelin sheath compaction previously demonstrated in a similar model of hypothyroidism.

Sucralose sweetener in vivo effects on blood constituents radiolabeling, red blood cell morphology and radiopharmaceutical biodistribution in rats.

Effects of sucralose sweetener on blood constituents labelled with technetium-99m ((99m)Tc) on red blood cell (RBC) morphology, sodium pertechnetate (Na(99m)TcO(4)) and diethylenetriaminepentaacetic acid labeled with (99m)Tc ((99m)Tc-DTPA) biodistribution in rats were evaluated. Radiolabeling on blood constituents from Wistar rats was undertaken for determining the activity percentage (%ATI) on blood constituents. RBC morphology was also evaluated. Na(99m)TcO(4) and (99m)Tc-DTPA biodistribution was used to determine %ATI/g in organs. There was no alteration on RBC blood constituents and morphology %ATI. Sucralose sweetener was capable of altering %ATI/g of the radiopharmaceuticals in different organs. These findings are associated to the sucralose sweetener in specific organs.

QUANTITATIVE ANALYSIS OF SMOOTH MUSCLE FIBERS IN CORPUS CAVERNOSUM OF HUMAN FETUSES

PURPOSE Quantify objectively the normative distribution and the percentage of smooth muscle fibers in the corpus cavernosum of human fetuses with 24 weeks post-conception (WPC) of gestational age. MATERIAL AND METHODS We studied 7 penises taken from 7 fresh human fetuses. We analyzed 5 randomized sections from each penis and in every section we analyzed 3 fields, totaling 15 fields per penis and 105 fields for the final results. Immunohistological staining for the smooth muscle fibers was used to accentuate the differences between the intracavernous structures (smooth muscle fibers and collagen fibers). The fields studied were digitized with a final magnification of 450X and a computerized analysis of the smooth muscle fibers was performed with image analyzer software. The percentage of smooth muscle fibers per standard square area was estimated and the mean value was used for each penis. RESULTS The distribution of smooth muscle fibers in the corpus cavernosum of human fetuses with 24 WPC of gestational age ranged from 17.52% to 27.76% of the total area. The mean value was 22.72% and the standard deviation was 3.56. CONCLUSIONS Our results show that the percentage of smooth muscle cells in corpus cavernosum of human fetuses with 24 WPC of gestational age is significantly smaller when compared with the data available for adult cadavers.

Expressions of vascular endothelial growth factor and nitric oxide synthase III in the thyroid gland of ovariectomized rats are upregulated by estrogen and selective estrogen receptor modulators.

BACKGROUND Estrogen promotes the growth of thyroid cells. Therefore, we analyzed the influence of estrogen and selective estrogen receptor modulators (SERMs) on the expression of vascular endothelial growth factor (VEGF) and nitric oxide synthase III (NOS III) in the thyroid gland of ovariectomized (Ovx) rats. METHODS Wistar rats were divided into five groups, and bilateral ovariectomies were performed, except on the Sham-operated controls (Sham). Rats were grouped as follows: Sham; Ovx; and Ovx rats treated with daily subcutaneous injections of estradiol benzoate 3.5 microg/kg, tamoxifen 2.5 mg/kg, or raloxifene 2.5 mg/kg for 50 consecutive days. Control animals received vehicle (propyleneglycol), and at the end of the treatment, rats were sacrificed. The thyroid glands were excised, weighed, and processed for analysis of the expression of VEGF or NOS III by immunohistochemistry. The mean vascular areas were evaluated by immunodetection of alpha-smooth muscle actin. RESULTS Thyroid weight and mean vascular area were lower in Ovx as compared with Sham, Ovx + estradiol benzoate, Ovx + Tam, or Ovx + Ral (p < 0.01). VEGF (p < 0.01) and NOS III expressions (p < 0.05) were significantly lower in the Ovx group, as compared with Sham, Ovx + estradiol benzoate, Ovx + Tam, and Ovx + Ral. Immunoreactivity for both VEGF and NOS III was mainly detected in the cytoplasm of the follicular epithelial cells. CONCLUSIONS Our data suggest that estrogen and SERMs regulate the thyroid gland vascularization and that tamoxifen and raloxifene behave like estrogen does. Estrogen and SERMs upregulate VEGF and NOS III in such a way as to reverse the effects detected on the thyroid microvasculature of the Ovx rats.

The ingestión of a Nectandra membranácea extract changes the bioavailability of technetium-99m radiobiocomplex in rat organs

The radiobiocomplexes labeled with technetium-99m (Tc-99m) have been widely used in nuclear medicine in single photon emission computed tomography and in basic research. The aim of this study was to assess the influence of a Nectandra membranacea extract on the bioavailability of the sodium pertechnetate (Na(99m)TcO(4)) radiobiocomplex in rat organs. The animals were treated with a N. membranacea extract (30 mg/ ml), for 6 days. Na(99m)TcO(4) was injected, the organs were isolated and weighed, and the radioactivity was determined in each organ (%ATI/organ). The %ATI/organ was divided by the mass of each organ to calculate the %ATI/g. A significant increase of the %ATI/organ of Na(99m)TcO(4) was observed in muscle and thyroid as well as in the %ATI/g in the heart, kidney and thyroid. These findings could result from the interaction between components of the plant extract and the radiobiocomplex which may influence the uptake Na(99m)TcO(4) in rat organs. Therefore, precaution is suggested in the interpretation of nuclear medicine results in patients using this herb.

Differences in Brazilian strains of Schistosoma mansoni evaluated by means of morphometric analysis of cercariae of both sexes

Morphometrics of Brazilian strains (BH, SJ and CMO) of Schistosoma mansoni cercariae were obtained with a computerized image analyzer (IMAGE PRO PLUS, MEDIA CYBERNETICS), considering the following characters: body area, tail, furcae, oral and ventral suckers and distance between them. For statistical analysis, the variance test (one-way Anova) was applied and significant differences of p< 0.05 were considered. All morphometric values in the BH strain were significantly higher (p< 0.05) than in the others. Lower values were obtained in females of SJ strain for all characters, excepting the body area. Only this character showed to be significantly different in males and females of the three strains. Specimens of both sexes in the BH and SJ strains showed significant differences regarding all characters. It was observed that this morphometric analysis permits the characterization of strains and also the sex identification in S. mansoni cercariae. Due to its feasibility, this method can be applied as a tool in laboratories devoid of more complex equipment.