Gustavo Dias Ferreira

Prevalência de dor nas costas e fatores associados em adultos do sul do Brasil: estudo de base populacional

OBJECTIVES To identify the prevalence of spinal pain and possible prognostic factors in a representative sample of Pelotas, RS, Brazil. METHODS Cross-sectional study evaluated 972 adults aged between 20 and 69 years, of both sexes, residents in a urban area. The questionnaire included socio-economic, demographics, behavioral and health-related questions. Spinal pain was defined as any pain or discomfort in the spine somewhere in the last 12 months, either in the cervical, thoracic or lumbar area. RESULTS The prevalence of spinal pain was 63.1% (95% CI 60.0 to 66.1) being lower back the most prevalent condition (40%). Female gender 1.24 (1.12 to 1.37) and poor health status(p<0.001) were the variables that remained associated with the presence of spinal pain in the final model. CONCLUSIONS The prevalence of back pain is important as it is associated with activity limitation and with health care utilization.

Protein Expression of Estrogen Receptors α and β and Aromatase in Myometrium and Uterine Leiomyoma

Background: Leiomyomas are the most common tumors of the female reproductive tract and a major public health problem. The mechanism of tumorigenesis is unknown, but evidence suggests that estrogens regulate cell proliferation and myoma growth. This effect might be due to different amounts of estrogen receptors (ERα and ERβ) in normal and myoma tissues and overexpression of aromatase P450 in myomas. Purpose: To assess protein expression of ERs and aromatase in leiomyomas and normal adjacent myometrium of premenopausal women. Methods: Samples were collected from 12 premenopausal women admitted for abdominal hysterectomy due to fibroids. Results: The protein expression of ERα, ERβ and aromatase was similar in leiomyoma and normal myometrium (p = 0.239, p = 0.695 and p = 0.203, respectively). Conclusions: In this analysis of 12 matched leiomyoma and myometrial samples, the data do not support the theory that overexpression ERα, ERβ and aromatase in uterine leiomyomas compared to adjacent myometrium are the cause of tumor growth. The estrogens may exert their growth-stimulatory effects on leiomyomas intermediated by other elements, such as cytokines and growth or apoptosis factors. The effect of estrogen on the growth and development of fibroids is complex and far from being completely understood.

Metformin modulates PI3K and GLUT4 expression and Akt/PKB phosphorylation in human endometrial stromal cells after stimulation with androgen and insulin

OBJECTIVE To assess the effect of metformin on expression of Akt, ERK, PI3K and GLUT4, proteins associated with the growth factor signaling cascade, in human endometrial stromal cells after stimulation with androgen and insulin. STUDY DESIGN Primary culture of endometrial stromal cells were stimulated in different groups with estrogen, progesterone, androgen and insulin and treated with metformin for 10min, 24h and 48h. After 14 days, proteins were extracted for Western blot analysis. RESULTS PI3K and GLUT4 expression were increased in the insulin-treated group and further attenuated when metformin was added. The ERK protein was not affected, whereas the Akt phosphorylation was significantly decreased by the action of metformin. CONCLUSION Metformin affects human endometrial stromal cells by acting on proteins related to growth factors, usually increasing their expression when combined with insulin. Akt phosphorylation was inhibited by metformin, possibly due to its anti-proliferative action.

Human Granulosa Cells: Insulin and Insulin-Like Growth Factor-1 Receptors and Aromatase Expression Modulation by Metformin

Background/Aim: Granulosa cells are the source of the most important ovarian steroids. Even in patients without significant improvement in metabolic parameters, metformin has apparently an important effect on the ovary. The aim of this study was to evaluate gene and protein expression of an insulin receptor (IR), insulin-like growth factor-1 (IGF1) receptor (IGF1R) and aromatase in granulosa cells treated with metformin and insulin. Methods: Luteinized granulosa cells were collected from 27 patients during in vitro fertilization procedures. Cells were isolated, stored in culture for 24 h and divided into four groups: control; metformin for 30 min, and metformin for 30 min plus insulin for 30 or 60 min. Results: IR and IGF1R mRNA expression was significantly enhanced by metformin but was not affected by insulin. Aromatase mRNA expression was significantly reduced in metformin-incubated cells following stimulation with insulin for 30 min. No statistical differences were found in IGF1R and aromatase protein expression, and IR expression was not detected. Conclusion: A direct effect of metformin on the gene expression of IGF1R, IR and aromatase was observed. Further studies should investigate the role of IGF1R, IR and aromatase in ovarian physiology for a better understanding of the effect of metformin.

Impedance-based fault location for overhead and underground distribution systems

This paper presents an extended formulation for fault location on electric distribution systems based on one-terminal measurement of apparent impedance. The method is developed using phase-components analysis to account for the inherent unbalanced operation of distribution feeders. Since distribution loads present a stochastic variation through time, a technique for compensation of load variation in both magnitude and angle is also presented. The proposed developments include two general fault location equations that account for any fault type. An iterative algorithm to compensate the line capacitive current component is also provided, thus enabling the application of the technique to long rural and underground systems, in addition to overhead distribution systems. Test results show the accuracy and robustness of the fault location algorithm to different fault types, distances and resistances, considering systems load profile variations up to ± 50%.

Insulin stimulation of Akt/PKB phosphorylation in the placenta of preeclampsia patients

CONTEXT AND OBJECTIVE Preeclampsia is a multi-systemic disease and one of the most frequent severe health problems during pregnancy. Binding of insulin triggers phosphorylation and activates cytoplasmic substrates such as phosphatidylinositol 3 kinase (PI3K). Phosphorylation of membrane phosphoinositide 2 (PIP2) to phosphoinositide 3 (PIP3) by PI3K starts Akt/PKB activation. Defects in phosphorylation of the insulin receptor and its substrates have an important role in insulin resistance. Studies have shown that insulin resistance is associated with preeclampsia and its pathophysiology. The aim here was to investigate insulin stimulation of the Akt/PKB pathway in the placenta, in normal and preeclampsia parturients. DESIGN AND SETTING Cross-sectional study in a tertiary public university hospital. METHODS Placentas were collected from 12 normal and 12 preeclampsia patients. These were stimulated and analyzed using Western blot to quantify the Akt/PKB phosphorylation. RESULTS The insulin stimulation was confirmed through comparing the stimulated group (1.14 ± 0.10) with the non-stimulated group (0.91 ± 0.08; P < 0.001). The phosphorylation of Akt/PKB did not differ between the placenta of the normal patients (1.26 ± 0.16) and those of the preeclampsia patients (1.01 ± 0.11; P = 0.237). CONCLUSIONS In vitro insulin stimulation of the human placenta has been well established. There was no difference in Akt/PKB phosphorylation, after stimulation with insulin, between placentas of normal and preeclampsia patients. Nevertheless, it cannot be ruled out that the Akt/PKB signaling pathway may have a role in the pathophysiology of preeclampsia, since the substrates of Akt/PKB still need to be investigated.

A hybrid impedance and transient based analysis technique for fault location in distribution networks

This paper presents a hybrid method for fault location in distribution networks. An impedance-based fault location formulation, taking into account unbalanced operation, presence of intermediate loads, laterals, and time-varying load profile was developed in order to estimate the fault distance. The faulty section is then identified through the transient evaluation with focus on high frequency analysis using different signal processing techniques. The proposed method was evaluated using a real distribution feeder with 241 buses, simulated through the ATP/EMTP software considering different fault types, resistances and locations.

Multi-objective optimization model for distribution systems restoration

This paper presents the development of a multi-objective optimization explicit model for distribution systems restoration. The main goal of the methodology is to determine the combination of maneuvers devices to be operated in order to maximize the number of customers with restored supply in the post-fault period and to minimize the time required by the process. The proposed formulation considers devices with arbitrary operation times, allowing the representation of automatic and manual maneuvers switches as well as, their effects on the duration of outages. In the proposed methodology, the supply restoration of distribution systems is formulated as a Mixed-Integer Linear Programming model. The proposed methodology was validated using a real distribution system. It is being implemented in one of the computational modules of the “SIRIs Platform” (Smart Grid Simulator), currently under development by NEO DOMINO and UFRGS in a research project supported by CELESC Distribuição S.A., Brazil.