Age-related changes of norepinephrine content in kidneys of spontaneously hypertensive and Wistar-Kyoto rats

Renal norepinephrine (NE) content was determined during the development of spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto (WKY) rats in an attempt to correlate biochemical changes with the reported functional changes occurring in hypertension development in the SHR. In contrast to WKY rats, in which the levels of NE remained relatively constant with age, renal NE content in the SHR was highest at the 4th week of age, decreasing transiently during the 5th, 6th, and 7th weeks, and then again reaching a plateau during the 8th week. The fall in NE content in the kidney is associated with a rise in blood pressure with age in SHR and suggests a relationship between NE levels and hypertension.     

Dissociation of the pro-apoptotic effects of bisphosphonates on osteoclasts from their anti-apoptotic effects on osteoblasts/osteocytes with novel analogs

Bisphosphonates induce osteoclast apoptosis, thereby decreasing bone resorption and reducing the rate of bone remodeling. Earlier work from our group and others has demonstrated that, additionally, bisphosphonates prevent osteoblast and osteocyte apoptosis in vivo and in vitro, raising the possibility that perhaps part of their anti-fracture efficacy may result from preserving the integrity of the osteocyte network and prolonging the working time of bone forming cells. Whereas induction of osteoclast apoptosis results from inhibition of the mevalonate pathway or from conversion to toxic ATP analogs, prevention of osteoblastic cell apoptosis is mediated by connexin43 hemichannel opening and activation of the extracellular signal-regulated kinases (ERKs). We examined here the ability of several bisphosphonates, including novel analogs, to exert these two effects. All 16 bisphosphonates studied inhibited etoposide-induced apoptosis of MLO-Y4 osteocytic cells and osteoblastic cells derived from calvaria, with EC50 between 10(-12) and 10(-10) M. On the other hand, only 10 analogs induced apoptosis of RAW-264.7-cell-derived osteoclasts. Each of the 6 bisphosphonates that lack pro-apoptotic activity in osteoclasts but retain anti-apoptotic activity in osteoblasts and osteocytes has a structural-related analog that is active in both cell types. These findings indicate that the structural prerequisites for the anti-apoptotic effect of bisphosphonates on cells of the osteoblastic lineage are less stringent than the ones required to induce osteoclast apoptosis and confirm that bisphosphonates act on the two cell types by distinct mechanisms. Preservation of osteoblast and osteocyte viability without inducing osteoclast apoptosis by these bisphosphonates analogs opens new possibilities for the treatment of bone fragility in conditions in which a decrease in bone remodeling is not desirable.     

Risk factors associated with colonization by pneumococci with reduced susceptibility to fluoroquinolones in adult outpatients

We developed a case-control study in order to identify risk factors associated with pharyngeal colonization by Streptococcus pneumoniae with reduced susceptibility to fluoroquinolones (ciprofloxacin MIC, > or =4 microg/ml). A total of 400 patients were studied for colonization by quinolone-nonsusceptible S. pneumoniae (QNSP) isolates and risk factors for this colonization. Isolate susceptibility was determined by the agar dilution method. Forty patients were colonized by QNSP (case patients), and 360 patients were not colonized by QNSP (control patients). The MIC range of ciprofloxacin for QNSP isolates was 4 to 8 microg/ml. No isolates were resistant to levofloxacin and moxifloxacin. Risk factors significantly associated with QNSP colonization, according to univariate analysis, were recent hospitalizations (odds ratio [OR], 3.43; 95% confidence interval [CI], 1.6 to 7.2; P < 0.01) and prior exposure to fluoroquinolones (OR, 6.04; 95% CI, 3.0 to 12.0; P < 0.01). Other factors such as chronic obstructive pulmonary disease (OR, 1.94; 95% CI; 0.7 to 5.0), prior exposure to penicillins (OR, 1,68; 95% CI, 0.8 to 3.3) and prior exposure to macrolides (OR 2; 95% CI, 0.6 to 6.2) were more frequent among patients colonized with QNSP, but there was no statistical significance. Multivariate analysis showed that exposure to fluoroquinolones was the only independent factor associated with colonization by QNSP (OR, 4.2; 95% CI, 1.8 to 9.4; P < 0.01). Throat colonization by QNSP is becoming frequent, though most of these isolates (all the isolates in this case) remain susceptible to newer fluoroquinolones. Previous treatment with fluoroquinolones seems to be the main risk factor associated with colonization by QNSP.     

A Scaffold-Free Multicellular Three-Dimensional In Vitro Model of Osteogenesis

In vitro models of osteogenesis are essential for investigating bone biology and the effects of pharmaceutical, chemical, and physical cues on bone formation. Osteogenesis takes place in a complex three-dimensional (3D) environment with cells from both mesenchymal and hematopoietic origins. Existing in vitro models of osteogenesis include two-dimensional (2D) single type cell monolayers and 3D cultures. However, an in vitro scaffold-free multicellular 3D model of osteogenesis is missing. We hypothesized that the self-inductive ossification capacity of bone marrow tissue can be harnessed in vitro and employed as a scaffold-free multicellular 3D model of osteogenesis. Therefore, rat bone marrow tissue was cultured for 28 days in three settings: 2D monolayer, 3D homogenized pellet, and 3D organotypic explant. The ossification potential of marrow in each condition was quantified by micro-computed tomography. The 3D organotypic marrow explant culture resulted in the greatest level of ossification with plate-like bone formations (up to 5 mm in diameter and 0.24 mm in thickness). To evaluate the mimicry of the organotypic marrow explants to newly forming native bone tissue, detailed compositional and morphological analyses were performed, including characterization of the ossified matrix by histochemistry, immunohistochemistry, Raman microspectroscopy, energy dispersive X-ray spectroscopy, backscattered electron microscopy, and micromechanical tests. The results indicated that the 3D organotypic marrow explant culture model mimics newly forming native bone tissue in terms of the characteristics studied. Therefore, this platform holds significant potential to be used as a model of osteogenesis, offering an alternative to in vitro monolayer cultures and in vivo animal models.     

Forum on aging and skeletal health: summary of the proceedings of an ASBMR workshop

With the aging of the population, the scope of the problem of age-related bone loss and osteoporosis will continue to increase. As such, it is critical to obtain a better understanding of the factors determining the acquisition and loss of bone mass from childhood to senescence. While there have been significant advances in recent years in our understanding of both the basic biology of aging and a clinical definition of age-related frailty, few of these concepts in aging research have been evaluated adequately for their relevance and application to skeletal aging or fracture prevention. The March 2011 Forum on Aging and Skeletal Health, sponsored by the NIH and ASBMR, sought to bring together leaders in aging and bone research to enhance communications among diverse fields of study so as to accelerate the pace of scientific advances needed to reduce the burden of osteoporotic fractures. This report summarizes the major concepts presented at that meeting and in each area identifies key questions to help set the agenda for future research in skeletal aging.     

Electroconvulsive stimuli selectively affect behavior and neuropeptide Y (NPY) and NPY Y(1) receptor gene expressions in hippocampus and hypothalamus of Flinders Sensitive Line rat model of depression.

Previously we reported that basal neuropeptide Y (NPY)-like immunoreactivity-(LI) in hippocampus of the "depressed" Flinders Sensitive Line (FSL) rats was lower compared to the control Flinders Resistant Line (FRL) and that electroconvulsive stimuli (ECS) raise NPY-LI in discrete brain regions. Here we studied NPY mRNA expression, NPY Y(1) receptor (Y(1)) mRNA expression and binding sites, and behavior under basal conditions (Sham) and after repeated ECS. Baseline NPY and Y(1) mRNAs in the CA1-2 regions and dentate gyrus were lower while the Y(1) binding was higher in the FSL. ECS had larger effects on both NPY and behavior in the FSL rats. ECS increased NPY mRNA in the CA1-2, dentate gyrus and hypothalamus in FSL, but only in the dentate gyrus in FRL. ECS also increased Y(1) mRNA in the CA1-2, dentate gyrus and the parietal cortex in both strains, while in the hypothalamus the increase was observed only in the FSL rats. Consistently with Y(1) mRNA increase, Y(1) binding was downregulated in the corresponding regions. ECS decreased FSL immobility in the Porsolt swim test. These findings suggest that NPY is involved in depressive disorder and that antidepressant effects of ECS may in part be mediated through NPY.