Calcium-dependent spike-frequency accommodation in hippocampal CA3 nonpyramidal neurons

Interneurons of the hippocampal formation are traditionally identified electrophysiologically as those cells that fire trains of weakly accommodating action potentials in response to depolarizing current injection. We studied the firing properties of nonpyramidal neurons in the five substrata of the CA3b region of hippocampus. With the use of whole cell recording methods we found that nonpyramidal neurons fired in a range from weak to strong spike-frequency accommodation (SFA) that was calcium dependent. Slow afterhyperpolarizations were not associated with strong SFA. In addition a subset of interneurons ( approximately 20%) fired with an irregular firing pattern that was generally calcium independent. These results suggest a calcium-dependent mechanism for SFA in nonpyramidal neurons that is distinct from pyramidal cells and further demonstrates the heterogeneity of hippocampal interneurons.     

The effects of economic and policy incentives on carbon mitigation technologies

The ability to estimate the likely effects of potential climate change policies on energy use and greenhouse gas (GHG) emissions requires an improved understanding of the relationship between different policy alternatives and energy-saving and GHG-reducing changes in technology. A particularly important and understudied aspect of this set of issues is the conceptual and empirical modeling of how the various stages of technological change are interrelated, how they unfold over time in response to market forces, and the differential impact of various policies (for example, R&D subsidies, environmental taxes, information programs). We summarize several contributions to this literature and suggest promising areas for continued research on empirical analysis and modeling of induced technological change.     

Restitution in transition countries

Changing the property rights arrangements to land and buildings is a fundamental step in the transformation process underway in Eastern and Central Europe and elsewhere. The concept of property hinges on the choice of property conventions adopted by each society. Defining what property means is a complex and controversial task, especially when the scope of change in transition countries is so dramatic. Restitution is often a first step in acknowledging a latent property rights paradigm in these nations. Since property rights form the foundation of how and why economies function, it is important to identify the theoretical and empirical evidence relating property rules to economic outcomes. In this paper, we investigate why restitution is implemented in some countries but not in others. Further, if restitution is adopted, how is it implemented? We speculate that the choice of restitution as a property institution may be a proxy for the development of future institutions.     

Depression, working models of others, and relationship functioning.

Two studies examined depressives' working models of others and the relative contribution of these models and depression to relationship functioning. Respondents reported on their childhood relationships, adult attachment style, and relationship functioning. Study 1 compared 163 mildly depressed and nondepressed college women (aged 17–48 yrs), and Study 2 compared 25 married women recovering from clinical depression with 23 nondepressed married women (mean age 40 yrs for both groups). Mildly depressed college women evidenced greater preoccupation and fearful avoidance in romantic relationships than did nondepressed women; recovering depressed women evidenced greater fearful avoidance. In both studies, relationship functioning was predicted more strongly by adult attachment style than by depression status. Among college women, positive experiences with mother also were linked to better relationship functioning; however, attachment style and depression status mediated this effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Peak bone mass in young healthy men is correlated with the magnitude of endogenous growth hormone secretion

GH plays a key role during adolescence in longitudinal bone growth and the attainment of peak bone mass. We explored the hypothesis that in early adulthood, bone mineral accretion and/or maintenance in men with normal GH and bone mineral status are related to the magnitude of endogenous GH secretion. Overnight plasma GH concentrations (sampled every 10 min from 2100-0500 h) were measured in 15 healthy, lean, Caucasian men (age, 24+/-1 yr; body mass index, 22.6+/-0.6 kg/m2; mean +/- SE). Total body, femur, and lumbar spine bone mineral mass/density were measured by dual energy x-ray absorptiometry. Total body and femoral bone mineral mass correlated with both total nocturnal GH and maximal GH concentrations even when bone mineral mass was adjusted by height (P = 0.005-0.02; r = 0.58-0.74). Neither spinal nor total body bone mineral density (BMD) correlated with GH. Maximum GH correlated with the BMD of all four femoral sites (P = 0.01-0.04; r = 0.55-0.66), whereas total nocturnal GH correlated with only one (trochanter; P = 0.01; r = 0.64) femoral site. Our data support the hypothesis that GH continues to play a role in the accretion and/or maintenance of bone mass in young men. This relationship is more evident in the bone mineral mass achieved than in the BMD.     

A pilot study comparing severely and persistently mentally ill opiate-addicted patients in dual-diagnosis treatment with patients in methadone maintenance

Retroviral vector gene transfer strategies are currently being developed to treat a variety of hematopoietic disorders. To date, genetic modification of human pluripotent hematopoietic stem cells has been inefficient. In the present study we developed reagents and procedures for rapidly screening retroviral vector gene transfer conditions using a multiparameter fluorescence-activated cell sorting (FACS) assay. To identify transduced cells using FACS analysis, we developed a retroviral vector, termed MN, which stably expressed high levels of a truncated version of the low-affinity nerve growth factor receptor (LNGFR). In addition, procedures were developed for enriching CD34+ cells from cryopreserved umbilical cord blood. These cells were transduced with MN and evaluated using multiparameter FACS analysis for expression of CD34, CD38, and LNGFR. Stem cell maintenance was determined by measuring the CD34hi and CD34hiCD38lo/- cells remaining after ex vivo gene transfer. Gene transfer into these cells was measured by evaluating cells expressing high levels of LNGFR. Initial studies with this assay and with in vitro functional assays indicated that retroviral gene transfer following pre-incubation with a variety of cytokines in serum containing conditions resulted in 1) poor maintenance of hematopoietic stem cells and 2) gene transfer predominantly in relatively mature cells. When gene transfer in serum-free conditions was performed, some improvement was observed in the maintenance of cells retaining primitive immunophenotypes with no reduction in the gene transfer efficiency. The MN vector and multiparameter FACS analysis will be useful in efficiently screening ongoing efforts designed to improve stem cell gene transfer.     

A normal initial colonoscopy after age 50 does not predict a polyp-free status for life

OBJECTIVES: The prevalence of colon polyps increases with age in the general population. It is unknown whether a lack of adenomatous polyps determined at one time point after the age of 50 is predictive of a subsequent low risk of polyp development. METHODS: Twenty-nine patients between ages 50 and 70 who had no prior history of polyps and had a normal colonoscopy at least 5 yr previously were recruited for follow-up colonoscopy to evaluate the incidence of neoplastic disease in this presumably low-risk group. RESULTS: The incidence of adenomatous polyps after a mean of 5.74 yr was 41.4% (95% confidence interval: 23.5-61.1%). A total of 20 adenomatous polyps were found in 12 patients. Seven polyps were 5 mm or more in size. CONCLUSIONS: We conclude that in patients with no history of colonic neoplasia who are 50 yr old, or older, the finding of a normal colonoscopy does not predict diminished risk of neoplasia.