A potentially deleterious role of IGFBP-2 on bone density in aging men and women.

The role of the IGFs and IGFBPs on age-related changes in BMD in adult men and women is not well understood. Studying an age-stratified community based sample of 344 men and 276 women, we found higher IGFBP-2 levels to be associated with lower BMD. IGFBP-2, which increases with age in both men and women, was the strongest, most consistent predictor of BMD among the IGF/IGFBPs studied. INTRODUCTION: Insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) are important regulators of tissue growth and metabolism, but their association with BMD in adult men and women is controversial. MATERIALS AND METHODS: In an age-stratified, random sample of the community population, we examined the role of serum levels of IGF-I, IGF-II, and IGFBP-1, -2, and -3 on BMD of the proximal femur (total hip), lateral spine, midshaft, and ultradistal radius as measured by DXA. We explored the association before and after adjustment for potential confounders, including age, bioavailable estradiol and testosterone, sex hormone binding globulin (SHBG), and measures of total fat and skeletal muscle mass. RESULTS: We studied 344 men (age, 23-90 years) and 276 women (age, 21-93 years; 166 postmenopausal) not on hormone replacement or oral contraceptives. In both men and women, IGF-I and IGFBP-3 levels fell with advancing age, whereas IGFBP-2 levels tended to rise with age. There was an inverse association of IGFBP-2 with BMD at most skeletal sites in men and both premenopausal and postmenopausal women, whereas lower IGF-I and IGFBP-3 were associated with lower BMD in men and postmenopausal women only. Lower IGF-II was associated with lower BMD in men only. There were no associations between IGFBP-1 and BMD in either sex. After adjustment for age, in most cases, we found no further associations between IGF-I, IGF-II, or IGFBP-3 and BMD. In contrast, after age adjustment, higher IGFBP-2 remained a predictor of lower BMD in men and postmenopausal women at all sites except for the lateral spine (for men: r = -0.21, -0.20, and -0.19, all p < 0.001; and for postmenopausal women: r = -0.34, -0.24, and -0.25, all p < 0.01, for the total hip, midshaft, and ultradistal radius, respectively). IGFBP-2 remained an independent negative predictor of BMD in men, postmenopausal women, and all women combined after additional adjustment for bioavailable sex steroids, but not at all sites after adjustment for SHBG and muscle mass. In premenopausal women, IGFBP-2 had similar associations as seen in postmenopausal women, but they were weaker and not statistically robust. CONCLUSIONS: Among the IGF/IGFBPs in our study, IGFBP-2 was a key negative predictor of BMD among men and women, particularly postmenopausal women. Our findings suggest a potential role of the IGF/IGFBP system in regulating bone loss in aging men and women and identify a previously under-recognized, potentially deleterious role for IGFBP-2, a known inhibitor of IGF action that increases with age in both sexes. Whether the action of the IGF/IGFBP system on bone metabolism is mediated partly through its effects on muscle mass or SHBG deserves further study.     

RASER: a new ultrafast magnetic resonance imaging method.

A new MRI method is described to acquire a T(2)-weighted image from a single slice in a single shot. The technique is based on rapid acquisition by sequential excitation and refocusing (RASER). RASER avoids relaxation-related blurring because the magnetization is sequentially refocused in a manner that effectively creates a series of spin echoes with a constant echo time. RASER uses the quadratic phase produced by a frequency-swept chirp pulse to time-encode one dimension of the image. In another implementation the pulse can be used to excite multiple slices with phase-encoding and frequency-encoding in the other two dimensions. The RASER imaging sequence is presented along with single-shot and multislice images, and is compared to conventional spin-echo and echo-planar imaging sequences. A theoretical and empirical analysis of the spatial resolution is presented, and factors in choosing the spatial resolution for different applications are discussed. RASER produces high-quality single-shot images that are expected to be advantageous for a wide range of applications.     

GnRH receptor signalling to ERK: kinetics and compartmentalization.

Many hormones, neurotransmitters and growth factors influence their target cells by activation of mitogen-activated protein kinase cascades. The consequences of such activation reflect not only the magnitude, but also the kinetics and cellular compartmentalization of kinase activity. Gonadotropin-releasing hormone (GnRH) receptors are seven-transmembrane receptors that have undergone a period of rapidly accelerated molecular evolution in which the advent of type I mammalian GnRH receptors has been associated with the loss of the carboxyl-terminal tail, a structure present in all other seven-transmembrane receptors. Here, we review spatiotemporal aspects of extracellular-signal-regulated kinase activation by gonadotropin-releasing hormone receptors, emphasizing how the absence or presence of the carboxyl-terminal tail dictates the receptors' ability to engage and signal via arrestins.     

Perceptions of the most helpful nursing behaviors in a home-care hospice setting: caregivers and nurses.

The purpose of this study was to determine those nursing behaviors perceived as most helpful and least helpful by primary caregivers and by hospice nurses in a home-care hospice setting. A Q-sort of 60 nursing behaviors ranked from most to least helpful was completed by 20 caregivers, during the bereavement period and by five hospice nurses, who were currently employed by the hospice. These nursing behaviors were categorized as: Nursing behaviors related to the patient's physical needs; nursing behaviors related to the patient's psychosocial needs; and nursing behaviors related to the psychosocial needs of the caregivers.     

Prediction of Remission of Acute Posttraumatic Stress Disorder in Motor Vehicle Accident Victims

One hundred forty five individuals who sought medical attention as a result of a motor vehicle accident (MVA), and who were initially assessed 1 to 4 months post-MVA, were followed up prospectively for 6 months to determine how many of the 55 with posttraumatic stress disorder (PTSD) and the 43 with sub-syndromal PTSD would remit and what variables would predict remission. Thirty (55%) of those with initial PTSD had remitted at least in part by 6 months while 67% of those with sub-syndromal PTSD had remitted (and 5% had worsened). Four variables, including severity of initial symptoms, degree of initial physical injury, relative degree of physical recovery by 4 months and whether a close family member suffered a trauma during the follow-up interval, combined to classify 6-month clinical status of 84% of those with initial PTSD secondary to MVAs.     

Quantitative assessment of variables that influence soft-tissue electrovaporization in a fluid environment

Objectives. To evaluate the process of soft-tissue electrovaporization and to study variables that affect tissue clearance rates in a laboratory setting, in order to identify parameters that can optimize transurethral electrovaporization of the prostate.Methods. Fresh bovine skeletal muscle, equivalent in impedance and surface properties to the human prostate, was submerged in 3.3% sorbitol solution and electrovaporized with a grooved monopolar electrode attached to the weighted arm of a linear actuator. The effects of excursion rate, applied mechanical load, power setting, electrode configuration, and generator performance on the volume of tissue removed, were assessed.Results. Tissue removal increased significantly when electrode excursion rate was slowed from 25 to 15 mm/s (P <0.05) and then to 10 mm/s (P <0.05); when the load was increased from 20 to 50 g (P <0.005); and when dial power was increased from 120 to 150 W (P <0.01). Tissue removal was generator dependent. There was no significant difference between the Force 40 and the Force 2 (P > 0.4), but a new computer-controlled constant power output generator (Force FX) did significantly improve tissue vaporization at an equivalent power setting (P <0.005 and P <0.01, respectively). Tissue removal was also dependent upon electrode configuration, with the VaporTrode-Grooved Bar removing significantly more tissue than either an ungrooved roller bar of equivalent size or 2-mm smooth roller ball, respectively, both after a single pass (P <0.001 and P <0.05) and after five repeated passes (P <0.05 and P <0.005). The histologic depth of tissue thermal effect was less than 1 mm, but it was 38% greater for the VaporTrode-Grooved Bar (0.68 mm) than for the standard cutting loop (0.5 mm, P <0.01).Conclusions. Using a novel method to quantify tissue removal, we have demonstrated that electrode configuration, excursion rate, applied load, power setting, and generator performance are interdependent factors that influence the efficacy of the electrovaporization process in a fluid environment.