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Biomedical subjects

R P Gonçalves

Publications and source records attributed to R P Gonçalves.

At least 19 recordsLinked to original sources
PubMed2004

Diagnostic accuracy of fetal renal pelvis anteroposterior diameter as a predictor of uropathy: a prospective study.

OBJECTIVE: The purpose of this study was to assess the accuracy of prenatal ultrasound measurement of anteroposterior renal pelvis diameter (APD) to discriminate between significant uropathy and idiopathic renal pelvis dilatation. METHODS: One-hundred-and-three neonates who were found to have fetal renal pelvis dilatation, defined as presence of an APD > or = 5 mm, underwent systematic investigation for uropathies and were prospectively followed. An ultrasound scan was performed after the first week of postnatal life and all infants underwent a voiding cystourethrogram. Neonates with an APD larger than 10 mm underwent renal scintigraphy. Ultrasound scans, clinical examination and laboratory reviews were scheduled at 6-month intervals. Receiver-operating characteristics (ROC) curves were constructed to determine the best cut-offs for APD to identify renal units with significant uropathy as well as those requiring surgical intervention. Significant uropathy was defined as the presence of well-established urinary tract abnormalities or when there was abnormal renal scintigraphy. RESULTS: The estimated area under the curve for APD was 0.900 (95% CI, 0.841-0.942) indicating excellent power to discriminate between idiopathic pelvis dilatation and significant uropathy. The sensitivity and specificity for the 7.5 mm cut-off point were 97.9% and 40.6%, respectively. To identify infants who required surgical intervention, the calculated area under the curve was 0.953 (95% CI, 0.908-0.980). CONCLUSION: Our results suggest that measurement of APD is an excellent test to identify fetuses with significant uropathy, as well as those requiring postnatal intervention.

Area Under Curve↗
PubMed1997

Plasma kinetic behavior in hyperlipidemic subjects of a lipidic microemulsion that binds to low density lipoprotein receptors.

It was previously reported that a protein-free microemulsion (LDE) with structure roughly resembling that of the lipid portion of low density lipoprotein (LDL) was presumably taken up by LDL receptors when injected into the bloodstream. In contact with plasma, LDE acquires apolipoproteins (apo) including apo E that would be the ligand for receptor binding. Currently, apo were associated to LDE by incubation with high density lipoprotein (HDL). LDE-apo uptake by mononuclear cells showed a saturation kinetics, with an apparent K(m) of 13.1 ng protein/mL. LDE-apo is able to displace LDL uptake by mononuclear cells with a Ki of 11.5 ng protein/mL. LDE without apo is, however, unable to displace LDL. The uptake of 14C-HDL is not dislocated by increasing amounts of LDE-apo, indicating that HDL and LDE-apo do not bind to the same receptor sites. In human hyperlipidemias, LDE labeled with 14C-cholesteryl ester behaved kinetically as expected for native LDL. LDE plasma disappearance curve obtained from eight hypercholesterolemic patients was markedly slower than that from 10 control normolipidemic subjects [fractional clearance rate (FCR) = 0.02 +/- 0.01 and 0.12 +/- 0.04 h-1, respectively; P < 0.0001]. On the other hand, in four severely hypertriglyceridemic patients, LDE FCR was not significantly different from the controls (0.07 +/- 0.03 h-1). These results suggest that LDE can be a useful device to study lipoprotein metabolism.

Adult↗
PubMed1993

The effect of venous occlusion on the integration of vascularized cortical bone graft.

The biologic phenomena involved in the healing process of vascularized, cortical bone grafts, vascularized grafts with venous occlusion, and conventional cortical bone grafts, were studied in rabbits. The middle third of the radial diaphysis was the donor site, with a 1.6-cm-long bone cylinder delimited by double transverse osteotomies. The vascularized grafts were raised by extraperiosteal dissection, with preservation of their vascular pedicle, while the conventional grafts were obtained by subperiosteal dissection. The vascularized graft with venous occlusion had its draining vein ligated. Radiologic, scintigraphic, and histologic studies were undertaken at days 7, 15, 30, and 60 postoperatively. Results demonstrated that the vascularized graft healed earlier than the corresponding vascularized graft with venous occlusion and than the conventional graft, respectively. The vascularized graft with venous occlusion suffered some degree of impairment of its irrigation, probably due to retrograde block of the arterial blood flow. It underwent a degree of bone necrosis, followed by resorption and creeping substitution, which delayed its integration. This seemed to be a temporary effect, for it healed earlier than the conventional graft.

Anastomosis, Surgical↗
PubMed1990

Effect of cholinergic stimulation of the medial septal area on the secretory properties of atrial myocardial fibers.

Adult male Wistar rats weighing 240-260 g were implanted with stainless steel guide cannulae into the medial septal area (MSA). Cholinergic stimulation of the MSA increased natriuresis (344.6 +/- 13.8 vs 22.2 +/- 2.1 microEq for the controls), the number of atrial specific granules (61.0 +/- 6.7 vs 43.8 +/- 3.5 granules/100 microns 2 sarcoplasma for the controls), and the number of electron-dense vesicles near the sarcolemma or appearing to undergo exocytotic extrusion (50.0 +/- 2.3 vs 21.4 +/- 5.7 vesicles/100 microns sarcolemma for the controls). It is not yet clear how cholinergic stimulation of the MSA changes the secretory characteristics of atrial myocardial fibers. However, the present study provides evidence that release of an atrial natriuretic factor may be controlled by the central nervous system (CNS). This may occur through the sympathetic and parasympathetic innervation of the heart or through the release of some substance produced by the CNS or produced at another site whose release is controlled by the CNS.

Animals↗
PubMed1988

Effect of chronic alcoholism upon the parietal cells of the stomach of rats.

The effects of chronic alcoholism upon the parietal cells of the stomach of rats were studied providing to a group of animals, only sugar cane brandy "ad libitum" as liquid food. A group of control animals received tap water and to both groups it was provided a balanced solid diet. During the experiment the body weight as well as liquid and solid food consumption were rated each other day. The animals were sacrificed after 45, 90 or 180 d and the effects of alcoholism evaluated at the day of sacrifice through morphological and morphometric techniques. Our results allowed us to conclude that: 1) the body weight of alcohol-treated animals increased at much slower rates when compared to controls. (2) The treated animals ingested less liquid and solid food than controls. 3) The volume of gastric secretion (ml/h/100 g of body weight) was not affected but its HCl content (mEq/l) was smaller in alcoholic rats. 4) Discrete morphological disturbance of the gastric mucosa was observed only in animals that ingested alcohol for 45 d. In the longer treatments the appearance of the mucosa was quite similar to controls. 5) The secreting mass of parietal cells decreased in alcohol treated rats. This decrease was attributed to a reduction in number of these cells.

Alcoholism↗
PubMed1986

Studies on tendon healing. A comparison between suturing techniques.

An experimental study comparing Kessler's and Tsuge's techniques for tendon suture was undertaken in dogs. Both second and fifth flexor digitorum profundi tendons of the left forepaw were divided in the segment corresponding to zone 2 of human hands. Following division, the tendons to the second digit were repaired by Kessler's technique and those to the fifth digit by Tsuge's method. Results were evaluated by means of standard and polarized--light microscopy, intravascular dye injections and tensile strength tests. Both ordinary and polarized--light microscopy showed that a microscopical gap develops between the tendon ends, being filled in with healing tissue which undergoes progressive maturation. The tensile strength tests showed that the deformation (elongation) progress directly with load, up to the point of rupture; the suture thread does not interfere with this. Furthermore, strength increases with time. Intravascular dye injection showed that a net of newly formed blood vessels develops at the site of section and suture, previously destitute of macroscopical vessels. The new vessels tended to redistribute them selves to resemble the pattern in normally vascularized regions. It was not possible to detect, by means of the methods employed, any important difference between Kessler's and Tsuge's techniques for tendon suture.

Animals↗
PubMed1985

Ultrastructural changing of the rat parathyroid gland under various fixation methods.

Ultrastructural features of the rat parathyroid (PT) glands have been studied under 3 different glutaraldehyde fixation methods. Cell differences caused by fixation or due to functional conditions were evaluated. The changes of organelles and relationship of plasma membranes of chief dark-light cells, as well the pericapillary and intercellular spaces were used for this evaluation. Light cells were observed in all PT glands studied. PT glands adequately perfused presented light chief cells as transitional secretory form. Incompletely-perfused and immersion-fixed glands presented most of light chief cells as a fixation artifact. The same interpretation was given to intercellular spaces which appeared only in glands fixed by immersion. In adequately perfused glands interdigitated and straight plasma membranes of neighbour chief cells were tightly continuous with frequent desmosomes. Distended mitochondria, RER and Golgi cisternae as well vacuolizations of chief cell cytoplasm and connective tissue were characteristics of unadequately perfused glands. The best fixation method for a homogeneous preservation of all components of rat PT glands, which decreased the possibility of a wrong interpretation of normal variations, was perfusion through the left ventricle. Fixative with pH and osmolarity carefully controlled were injected after saline washing of the vascular bed.

Animals↗
PubMed1985

Light- and electron microscopic observations on parathyroid glands in different age groups of rats.

The parathyroid hormone (PTH) acts on bones, intestines, and kidneys to maintain the calcium homeostasis which, in turn, is a main factor in controling the parathyroid (PT) gland activity. In all mammals studied, the chief cells of PT glands changed their size, shape, and cytoplasmic structure due to different functional states which vary the serum calcium levels. The chief cells of the rat PT glands were classified as dark and light. The dark cells may constitute an active form, characterized mainly by the abundant free ribosomes, conspicuous rough endoplasmic reticulum, and GOLGI complexes, greater number of secretory granules (SG) and increased tortuosity of the plasma membranes as compared to the light ones which were considered as a less active type of cells. Due to different calcium requirements in newborn and young rats for the ossification of growing skeleton and in adult and senile rats with consolidate mature bones, the PT glands studied with electron microscope showed various cytological features. The parenchyma of newborn and young PT glands was composed by dark chief cells. The light chief cells were more frequent in adult and senile animals as a less active type of cell. Mature SG were only occasionally observed in dark cells of newborn, young and adult PT glands. They may constitute a reserve supply of PTH but probably not the main way of secretion, according to their little number. Another pool of PTH probably answers the needs for the small basal variations in the steady-state secretion and may be represented by the vesicles observed in the chief cells cytoplasm.

Aging↗
PubMed1984

Histological and ultrastructural observations of the attachment between the oral cavity of the fetus and the nipple of the mother in opossum (Didelphis azarae).

The mechanism of fixation of the fetus to the maternal nipple of opossum (Didelphis azarae) was studied in fetus of different ages through histological sections of the oral cavity keeping the nipple inside it. No organic connection was found between the maternal nipple and the tissues of the fetus. The increase of the nipple volume inside the oral cavity of the fetus and the imbrication between the corneous extracts of the nipple, palate and tongue epitheliums increase the fixation strength and contribute to the act of suckling.

Animals↗
PubMed1981

Effects of hemidecortication on the regulation of rat thyroid function.

1. Thyroid function in hemidecorticate and control rats was studied by the measurement of oxygen consumption (under basal conditions and after cold exposure) and radioiodine (131 I) uptake by the thyroid after a low-iodine diet for 30 days. 2. The oxygen uptake of male and female hemidecorticate rats under basal conditions (29 degrees C) did not differ significantly from that of the controls. The values observed for both experimental groups were relatively constant, ranging from 40 to 75 kcal h-1 m-2 for 2 to 50-day-old animals. 3. When hemidecorticate and control rats, age 60-65 days, were exposed to 7-8 degrees C for 5-6 h, the oxygen consumption of the hemidecorticate rats increased (83-84 kcal h-1 m-2) but to a lower extent than that of the controls (105-106 kcal h-1 m-2). 4. The rate of radioiodine (131 I) uptake by the thyroid gland of hemidecorticate rats was also lower than that of controls when the animals were maintained on a low-iodine diet. 5. These results show that, under basal conditions, the hypothalamic-pituitary-thyroid axis of hemidecorticate rats does not differ from that of control rats. However, when exposed to cold the hemidecorticate animals were not able to increase their oxygen consumption to the extent achieved by the control groups.

Animals↗
PubMed1978

Influence of autonomic denervation upon the kinetics of the ileal epithelium of the rat.

The effect of autonomic denervation upon the kinetics of the ileal epithelium of rats was studied by tracing 3H-thymidine labelled nuclei and counting mitotic figures and goblet cells. Counts of labelled nuclei and goblet cells provided information about cell migration along the intestinal epithelium. The mitotic index and turnover time of this population were calculated from the mitotic figures counts. Comparing denervated animals with sham operated controls, it was possible to conclude that autonomic denervation, either sympathectomy or parasympathectomy results in a decrease in mitotic activity. As a result of lower mitotic activity in the crypts, the turnover time increases and there is a delay in the migration of cells from the crypts towards the villi. Sympathectomy causes an early short-lived effect upon the kinetics of the crypt cell population, since after 27h there is a tendency to normality. Parasympathectomy produces a slower but continuous decline in mitotic activity.

Animals↗
PubMed1978

[Cutaneous dyschromia in three cases of phenylketonuria. Quantitative ultrastructural study of the basal layer of the epidermis (author's transl)].

The authors have studied skin color modifications in 3 cases of phenylketonuria and have observed the characteristic changes; fair skin and fair hair. In addition they noted hundred of pigmented pin point or slightly larger patches in the two more affected patients, in the areas exposed to sunshine. With regard to the ultrastructural study of the epidermis basal layer, the proportion of melanocytes in the two most severe cases was slightly higher than in the normal skin of 6 control subjects. Langerhans cells could not be acertained. The more severe was the disease the greater was the tendency for a lower proportion of keratinocytes containing melanin. There is a certain parallelism between the skin color modifications the biochemical examinations (blood level of phenylalanin and tyrosine) and the ultrastructural changes. The higher the blood level of phenlalanine and/or the more pronounced the disorders of skin color, the more evident would be the ultrastructural changes: higher proportion of melanocytes that usually do not produce the melanosomes, and lower percentage of keratinocytes with melanin. On the other hand, the ultrastructure of the basal layer would suggest the seriousness of clinical manifestations and/or the intesity of the metabolic error.

Child↗
PubMed1978

[Quantitative ultrastructural study of the epidermis basal layer in the vitiligo patches and in the marginal hyperchromic and normal skin (author's transl)].

To avoid any bias, the ultramicroscopic examination was performed by the morphologist without knowing whether the material examined was from the vitiligo patch or from the marginal hyperpigmented and normal skin. Only at the end of the investigation, he was informed about the code of the material. He had also been informed about the possibility of receiving skin biopsies from a patient without vitiligo, what in fact was done with the inclusion of one case of albinism. Six cases of vitiligo have been studied. The melanocytes usually have not been observed in the vitiligo patches, where a variable number of Langerhans cells were seen. In the melanocytes reached about 17 p. 100 of the cellular population; Langerhans cells were absents. In the marginal normal skin the average proportion of melanocytes was near 10 p. 100 of the cellular population and the Langerhans have been observed only in one case (1.8 p. 100 of the population). Regarding the keratinocytes of the marginal hyperpigmented and normal skin, respectively 75 p. 100 and 59 p. 100 contained melanin; in the vitiligo patches only in one case keratinocytes contained melanin (2.8 p. 100 of the keratinocytes population as an average).

Adult↗
PubMed1975

Effect of denervation on the mitotic index of the intestinal epithelium of the rat.

The infradiaphragmatic section of vagi nerves at the level of the diaphragm crura causes, on the third day after surgery, a reduction of the mitotic activity in the crypts of the intestinal epithelium of the rat. Moreover there is a drastic reduction in number of the goblet cells that remain concentrated at the lower third of the villi. After the third day after vagotomy there is a tendency to normality. Sympathectomy did not affect significantly the intestinal epithelium of the rat. When both surgeries were performed together, there was no additive effect.

Animals↗