Prevalence of HIV infection among psychiatric patients in a New York City men's shelter.

We report on the prevalence of human immunodeficiency virus (HIV) infection among psychiatric patients in a New York City shelter for homeless men. We reviewed the records of all 90 men discharged from the shelter psychiatry program to community housing over a 2-year period. HIV serostatus was recorded for 62 of the 90 men. Of these 62, 12 (19.4%) were positive. There were 28 men whose serostatus was not recorded. Data on the HIV risk behaviors of these 28 men suggested that seroprevalence could have been similarly high among them. The results indicate an urgent need to develop and apply preventive interventions for HIV in this population.     

How PEDF prevents angiogenesis: a hypothesized pathway

Pigment epithelium-derived factor (PEDF) is a multiple functional protein, coded by the serine proteinase inhibitor, clade F, member 1 (SERPINF1) gene, which has both anti-angiogenic activity and neurotrophic activity at the same time. Its antiangiogenic activity in the mammalian eye is the most potent known at this time. However, the mechanism(s) by which PEDF works in vivo is still uncertain. Some observations suggest that PEDF can simultaneously inhibit the migration and proliferation induced by vascular endothelial growth factor (VEGF), and then further inhibits angiogenesis by interacting with specific cell surface receptors, but no such receptor has been reported to date. Here we propose a hypothesis that PEDF exerts its function by binding with intergrins. Intergrin can therefore serve as the receptor of PEDF.     

Growth of brain stimulation reward as a function of duration and stimulation strength

The strength of a train of rewarding brain stimulation required to support a criterion level of operant performance declines hyperbolically as the duration is increased. This finding has been attributed to a process of leaky integration. However, the rate at which integration approaches asymptote has been shown to depend on stimulation strength, a finding that differs from the behavior of a simple leaky integrator. The authors replicate both findings and show that they are both well described by a new model that incorporates a hyperbolic strength-duration function, a logistic function mapping stimulation frequency onto reward intensity, and another logistic function mapping reward intensity onto performance.     

Use of site-specific antibodies to characterize the circulating form of big insulin-like growth factor II in patients with hepatitis C-associated osteosclerosis

Hepatitis C-associated osteosclerosis (HCAO) is a rare syndrome of adult-onset osteosclerosis. An understanding of the factor(s) leading to the stimulation of bone formation in these patients may provide novel anabolic approaches for the treatment of osteoporosis. We have demonstrated that HCAO patients have a specific increase in circulating big IGF-II (IGF-IIE) and IGF-binding protein-2 (IGFBP-2) levels, and that IGF-IIE and IGFBP-2 circulate together in a bioavailable, 50-kDa complex. Patients with nonislet cell tumor hypoglycemia (NICTH) also have increased circulating IGF-IIE and IGFBP-2 levels. However, HCAO patients do not exhibit hypoglycemia, nor do NICTH patients exhibit obvious osteosclerosis. Thus, to better understand the reason(s) for the differing clinical manifestations of the IGF-IIE excess in the two syndromes, we characterized IGF-IIE in HCAO and NICTH sera using recently developed antibodies (Ab) recognizing either the full-length IGF-IIE 89-amino acid C-terminal extension peptide (IIE(138-156) Ab) or specific cleavage forms of IGF-IIE (IIE(78-88) Ab and IIE(89-101) Ab). The predominant IGF-IIE form in HCAO serum migrated on SDS-PAGE as a single band at approximately 18 kDa that reacted with the IIE(89-101) Ab. On the other hand, the predominant form in NICTH serum migrated as a doublet of 14 and 16 kDa that reacted with the IIE(78-88) Ab. There results are consistent with differential processing of the IGF-IIE precursor at predicted cleavage sites producing IGF-IIE(1-104) and IGF-IIE(1-88) in HCAO and NICTH, respectively. As these two forms may have differing biological activities and/or targeting properties, our findings may explain at least in part the different manifestations of IGF-IIE overproduction in the two syndromes.     

Rates of return from hospital conversions

This article presents information on the rates of return obtained by purchasers of U.S. hospitals since the mid 1980s. The key hypothesis tested in this study was whether for-profit acquirers are able to purchase hospitals at below-market prices. We test the hypothesis by comparing internal rates of return to an estimate of the weighted cost of capital for all for-profit hospitals in the year the transaction occurred.     

Safe and effective regulation of hematocrit by gene gun administration of an erythropoietin-encoding DNA plasmid

This work examines the effect of delivering a DNA plasmid encoding murine erythropoietin (pVRmEpo) to BALB/c mice by gene gun. Whereas intramuscular injection elicits a rise in hematocrit persisting >8 months, intradermal delivery triggers the dose-dependent secretion of biologically active erythropoietin (Epo) for approximately 1 month. Repeated administration of pVRmEpo by gene gun elicits a stable increase in hematocrit. The source of the Epo produced following gene gun delivery was analyzed by periodically grafting the site of injection onto naive recipients. Results indicate that both stationary cells (presumably keratinocytes) and migratory (presumably dendritic) cells were transfected and secreted biologically active Epo in vivo. Gene gun administration of plasmid DNA appears to be safe, and provides an additional strategy for achieving the regulated secretion of an exogenous gene product.     

儿童癌症幸存者成年后的慢性疾病

由于治疗方法的进步,近80%的儿童和青少年癌症患者能够长期生存。在美国,约有270000例儿童癌症的幸存者,即每640名20至39岁成年人中就有一名幸存者。大量的幸存者有利于儿童癌症治疗后长期健康结果的研究。现在可以明确的是,化疗和放疗所致的儿童各器官系统损害在临床上可能潜伏多年。为了全面了解治疗儿童癌症而继发的健康问题,重要的是衡量三项长期结果:健康状况、死亡率和患病率。这三项中,关于前两项已有相当好的研究报道。在一项对20227例癌症5年生存者的回顾性分析中,Mertens等发现以下原因导致的超额死亡率具有统计学意义:继发癌症(…