Novel ball head screw and screwdriver design for implant-supported prostheses with angled channels: a finite element analysis

The primary objective of this study was to design the optimal geometry of a novel screwdriver, create the grooves on a ball head screw, and demonstrate its resistance to a torque of up to 40 Ncm at angulations of 0°, 15°, and 30° by using nonlinear finite element analysis. A secondary objective was to create a foolproof, easily recognizable system. The grooved ball head screw and geometry of the screwdriver, functioning from an angulation of 0° to 30°, was generated using Pro-ENGINEER Wildfire 5.0 software. Static structural analyses among bodies in contact were performed at different angles of 0°, 15°, and 30° at a torque of 20 Ncm and 40 Ncm using nonlinear finite element simulation by means of ANSYS 12.0. The maximum stress supported by the ball head screw and screwdriver was similar at 20 Ncm and 40 Ncm. Although greater deformations were found at 40 Ncm, these were small and might not affect the performance of the system. Further, the rupture torque value for the M2 connection was 55 Ncm for 0° and 30°, and 47.5 Ncm for 15°. Numerical simulation showed that the ball head system design can achieve the mechanical strength requirements expected for screws used in implant-supported restorations at an angulation of up to 30°. Finite element analysis showed this novel ball head screw and screwdriver system to be a good solution for angled screw channels in implant-supported prostheses

Influence of hormone therapy on the cardiovascular responses to stress of postmenopausal women

Abstract Epidemiological and psychophysiological data suggest that groups that differ in reproductive hormones and stress responses also differ in risk for cardiovascular disease. To evaluate the effects of hormone therapy on women's cardiovascular responses to laboratory stressors, 89 healthy postmenopausal women were tested twice, before and after exposure for about 8 weeks to one of the five conditions: placebo, Estratab (primarily estrone), Estratab plus Prometrium (micronized progesterone), Estratab plus Provera (synthetic progestin), and Estratest (same estrogen as in Estratab plus methyltestosterone). Results showed that women assigned to Estratab plus Prometrium and Estratest had diminished systolic blood pressure responses to stress upon retesting, whereas the other groups did not change in the level of their responses. Women assigned to Estratab plus Prometrium had diminished diastolic blood pressure responses during a speech stressor upon retesting, whereas women assigned to Estratab plus Provera increased. Our findings show that hormone therapy does affect women's stress responses, but they do not provide a simple explanation as to why groups at high and low risk for cardiovascular disease differ in reproductive hormones and stress responses.

Strategies and methods to study sex differences in cardiovascular structure and function: a guide for basic scientists

<p>Abstract</p> <p>Background</p> <p>Cardiovascular disease remains the primary cause of death worldwide. In the US, deaths due to cardiovascular disease for women exceed those of men. While cultural and psychosocial factors such as education, economic status, marital status and access to healthcare contribute to sex differences in adverse outcomes, physiological and molecular bases of differences between women and men that contribute to development of cardiovascular disease and response to therapy remain underexplored.</p> <p>Methods</p> <p>This article describes concepts, methods and procedures to assist in the design of animal and tissue/cell based studies of sex differences in cardiovascular structure, function and models of disease.</p> <p>Results</p> <p>To address knowledge gaps, study designs must incorporate appropriate experimental material including species/strain characteristics, sex and hormonal status. Determining whether a sex difference exists in a trait must take into account the reproductive status and history of the animal including those used for tissue (cell) harvest, such as the presence of gonadal steroids at the time of testing, during development or number of pregnancies. When selecting the type of experimental animal, additional consideration should be given to diet requirements (soy or plant based influencing consumption of phytoestrogen), lifespan, frequency of estrous cycle in females, and ability to investigate developmental or environmental components of disease modulation. Stress imposed by disruption of sleep/wake cycles, patterns of social interaction (or degree of social isolation), or handling may influence adrenal hormones that interact with pathways activated by the sex steroid hormones. Care must be given to selection of hormonal treatment and route of administration.</p> <p>Conclusions</p> <p>Accounting for sex in the design and interpretation of studies including pharmacological effects of drugs is essential to increase the foundation of basic knowledge upon which to build translational approaches to prevent, diagnose and treat cardiovascular diseases in humans.</p

An algorithm for treatment of infertile women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common condition with both a reproductive and metabolic phenotype. Women with PCOS often seek care because of infertility or menstrual cycle irregularities that result from chronic anovulation interspersed with occasional ovulatory cycles. Initially, it is important to delineate a differential diagnosis for oligo- or amenorrhea and to evaluate for disorders that may “masquerade” as PCOS. If fertility is a desired goal, then it is critical to optimize health conditions that impact fertility and gestation. Lifestyle modifications, including nutritional counseling and weight loss, should be a part of all treatment plans. Even minimal (5%) weight loss in obese women with PCOS improves both ovulation and pregnancy rates. The first line of treatment for ovulation induction remains the selective estrogen receptor modulator (SERM) clomiphene citrate. The role of insulin sensitizers, particularly metformin, remains unclear. A recent consensus panel recommended against its routine use in the absence of an elevated glucose or hemoglobin A1c. If a woman fails to achieve pregnancy after a trial of weight loss and six ovulatory cycles induced by clomiphene citrate, then ovulation induction with exogenous gonadotropin, with or without timed intrauterine insemination, or in vitro fertilitization, is a reasonable next step. Women with PCOS are particularly prone to excessive follicle development and are at increased risk for ovarian hyperstimulation syndrome (OHSS). Although limited data exist comparing approaches to ovulation induction or controlled ovarian stimulation in women with PCOS, the American Society for Reproductive Medicine recommends the use of “step-up” or “step-down” protocols in which a low dose of exogenous FSH or combined gonadotropins are employed in an attempt to constrain ovarian responsiveness. In vitro fertilization allows for the transfer of only one embryo or for cryopreservation of all embryos with subsequent transfer of a single embryo in a subsequent cycle without ovarian stimulation. Countless questions regarding pathogenesis and treatment of PCOS create opportunity for basic and clinical research and for refinement of existing therapeutic approaches