The incidence of T2-weighted MR imaging signal abnormalities in the brain of cocaine-dependent patients is age-related and region-specific.

BACKGROUND AND PURPOSE: Cocaine and its metabolites can produce vasospasm, and cocaine-dependent patients are at increased risk for stroke. Based on previous case reports, we hypothesized that the incidence of hyperintense brain lesions observed on T2-weighted MR images would also be increased in asymptomatic cocaine-dependent individuals. METHODS: Sixty-two male "crack" (smoked) cocaine-dependent participants ranging in age from 25 to 66 years were compared with 116 normal male control participants ranging in age from 25 to 80 years. Those with histories of neurologic symptoms or illnesses were excluded. The severity of hyperintense lesions was rated on a 0- to 3-point scale, and ratings of 3 were used in the data analysis as an indicator of a probable pathologic process. Three regions were separately rated: the cerebral white matter, insular subcortex white matter, and subcortical gray matter (basal ganglia and thalamus region). RESULTS: Significantly increased risk of severe lesions was observed in the two white matter regions of the cocaine-dependent group (odds ratio of 16.7 and 20.3) but not in the subcortial gray matter region (odds ratio of 1.4). In the insula subcortex white matter, the risk of lesions increased with age in the cocaine-dependant sample, but remained essentially absent among normal controls through the age of 80 years. In the cerebral white matter, the relationship of age and risk of lesion among normal participants was similar in shape to that in cocaine-dependent participants, but equivalent risk was seen 20 years earlier among cocaine-dependent participants. CONCLUSIONS: Cocaine-dependent participants had a significantly increased age-related risk of white matter damage. The possible clinical implications of this damage are discussed.     

原发性胆囊癌抑癌基因P53蛋白表达及其意义

目的 探讨抑癌基因Ｐ＾５３蛋白在原发性胆囊癌的表达及意义。方法 采用免疫组织化学方法检测了６０例原发性胆囊癌抑癌基因Ｐ＾５３蛋白的表达。结果 胆囊癌肿瘤细胞Ｐ＾５３蛋白的阳性反应率为３３．３％（２０／６０）,慢性胆囊炎及癌旁正常粘阳性反应率均为０,两者比较差异有显著意义（Ｐ〈０．００５）。结论 Ｐ＾５３蛋白的表达与肿瘤的分化程度有一定的关系,低分化胆囊腺癌中Ｐ＾５３蛋白阳性表达率明显高于高分化腺襄     

Cartilage and synovium of the peroneocuboid joint: an anatomic and histological study

The surface area, thickness, and composition of the articular cartilage of the peroneocuboid articulation and the location of the synovium were investigated in 15 cadaver foot specimens. The articulations of the medial side of the peroneus longus tendon and lateral side of the cuboid were covered with fibrous and hyaline cartilages, respectively. On the lateral tuberosity of the cuboid, there is a facet that has 79.37+/-20.24 mm2 articular cartilage area with an oval shape to conform to that of the articular surface of the peroneus longus tendon (articular cartilage area, 67.35+/-28.53 mm2) with which it articulates. The mean thickness of the articular cartilage of the peroneus longus tendon and cuboid was 0.34+/-0.08 and 0.52+/-0.07 mm, respectively. The peroneocuboid joint has its own joint capsule. The synovial cavity does not communicate with the sheath of the peroneus longus tendon. Synovial membranes were attached to the margins of the articular surfaces of the cuboid immediately peripheral to the cartilage region.     

Leptin-induced increase in sympathetic nervous and cardiovascular tone is mediated by proopiomelanocortin (POMC) products

The mechanism underlying the leptin-induced increased sympathetic nerve activity and cardiovascular tone was investigated in normal rats. The melanocortin (MC) peptides and other fragments derived from proopiomelancortin (POMC) have a diverse array of biological activities and have been implicated in mediating the feeding behavioral responses to leptin. In this study we evaluated the possible involvement of two major products of POMC, alpha-melanocyte stimulating hormone (alpha-MSH) and beta-endorphin, in mediating the effects of leptin on sympathetic activity and mean arterial pressure (MAP) in normal rats. Intraventricular (i.c.v.) cannulas were implanted in normal rats and allowed to recover. On the day of the study the animals were anesthetized with urethane alpha-chloralose and instrumented for the recording of MAP, lumbar sympathetic nerve activity (LSNA), and heart rate (HR). To determine the correlation between the leptin response and the POMC products, alpha-MSH and beta-endorphins were also injected into the lateral ventricle. alpha-MSH acted to increase MAP and LSNA while beta-endorphin decreased these parameters. Leptin administration by i.c.v. cannula increased the MAP and LSNA in normal rats. The i.c.v. administration of agouti protein, an alpha-MSH receptor antagonist, prior to leptin infusion blocked this response. Likewise, pretreatment with naloxone a beta-endorphin receptor antagonist also blocked the response to leptin. From these studies we conclude that the acute increased LSNA and MAP in response to i.c.v. leptin may be mediated by increased POMC and its subsequent production of breakdown product alpha-MSH and/or beta-endorphin and it is the subsequent action of alpha-MSH that increases MAP and LSNA by activation of the MC4 receptor. The naloxone antagonism of the leptin response is likely due to the blockade of presynaptic opioid inhibition of the MC4 receptor-mediated pressor response.     

Receptor tyrosine kinase tie 1 mRNA is upregulated on cerebral microvessels after embolic middle cerebral artery occlusion in rat

Tie 1 is an endothelial specific transmembrane receptor tyrosine kinase and may be required during angiogenesis. Using in situ hybridization, we measured tie 1 mRNA in ischemic brain (n=15). Rats were subjected to middle cerebral artery (MCA) occlusion by a single fibrin rich clot. Expression of tie 1 was not detected in non ischemic brain. Cerebral microvessels expressed tie 1 in the ischemic lesion as early as 2 h after MCA occlusion. The number of microvessels containing tie 1 mRNA decreased in the ischemic lesion at 8 h after MCA occlusion. However, expression of tie 1 increased on microvessels at 24 h and 14 days after ischemia and tie 1 was primarily localized to the microvessels bordering pan necrotic tissue. Ninety-seven percent of cerebral vessels which expressed tie 1 mRNA had diameters of 3.7+/-0.17 microm. Our findings suggest a role for tie 1 in cerebral microvascular remodeling after embolic stroke.     

Opioid peptide receptor studies, 11: involvement of Tyr148, Trp318 and His319 of the rat mu-opioid receptor in binding of mu-selective ligands

Previous data obtained with the cloned rat mu opioid receptor demonstrated that the "super-potent" opiates, ohmefentanyl (RTI-4614-4) and its four enantiomers, differ in binding affinity, potency, efficacy, and intrinsic efficacy. Molecular modeling (Tang et al., 1996) of fentanyl derivatives binding to the mu receptor suggests that Asp147, Tyr148, Trp318, and His319 are important residues for binding. According to this model, Asp147 interacts with the positively charged opiate agonist to form potent electrostatic and hydrogen-bonding interactions. In this study, the role of weak electrostatic and hydrogen-bonding "pi-pi" interactions of the O atom of the carbonyl group and the phenyl ring structures of RTI-4614-4 and its four enantiomers with residues Tyr148, Trp318, and His319 were explored via site-directed mutagenesis. Tyr148 (in transmembrane helix 3 {TMH3}), Trp318 (TMH7), and His319 (TMH7) were individually replaced with phenylalanine or alanine. Receptors transiently expressed in COS-7 cells were labeled with [125I]IOXY according to published procedures. Mutation of Tyr148 to phenylalanine reduced the binding affinities of some mu-selective agonists (2-7 fold) but did not alter the affinities of DAMGO, naloxone, and the non-selective opiates etorphine and buprenorphine. In contrast, this mutation significantly increased the binding affinities (decreased the Kd values) of [D-Ala2,D-Leu5]enkephalin, IOXY, and dermorphin. Mutation of Trp318 decreased opioid receptor binding to almost undetectable levels. Substitution of alanine for His319 significantly reduced binding affinities for the opioid ligands tested (1.3- to 48-fold), but did not alter the affinities of naloxone and bremazocine. These results indicate the importance of Tyrl48 and His319 for the binding of fentanyl derivatives to the mu receptor. Functional studies using the mutant receptors will provide additional insight into the mechanism of action of RTI-4614-4 and its four enantiomers.     

Increased apoptosis of immunoreactive host cells and augmented donor leukocyte chimerism, not sustained inhibition of B7 molecule expression are associated with prolonged cardiac allograft survival in mice preconditioned with immature donor dendritic cells plus anti-CD40L mAb.

BACKGROUND: We previously reported the association among donor leukocyte chimerism, apoptosis of presumedly IL-2-deficient graft-infiltrating host cells, and the spontaneous donor-specific tolerance induced by liver but not heart allografts in mice. Survival of the rejection-prone heart allografts in the same strain combination is modestly prolonged by the pretransplant infusion of immature, costimulatory molecule-(CM) deficient donor dendritic cells (DC), an effect that is markedly potentiated by concomitant CM blockade with anti-CD40L (CD154) monoclonal antibody (mAb). We investigated whether the long survival of the heart allografts in the pretreated mice was associated with donor leukocyte chimerism and apoptosis of graft-infiltrating cells, if these end points were similar to those in the spontaneously tolerant liver transplant model, and whether the pretreatment effect was dependent on sustained inhibition of CM expression of the infused immature donor DC. In addition, apoptosis was assessed in the host spleen and lymph nodes, a critical determination not reported in previous studies of either spontaneous or "treatment-aided" organ tolerance models. METHODS: Seven days before transplantation of hearts from B10 (H-2b) donors, 2x10(6) donor-derived immature DC were infused i.v. into C3H (H-2k) recipient mice with or without a concomitant i.p. injection of anti-CD40L mAb. Donor cells were detected posttransplantation by immunohistochemical staining for major histocompatibility complex class II (I-Ab) in the cells of recipient lymphoid tissue. CM expression was determined by two-color labeling. Host responses to donor alloantigen were quantified by mixed leukocyte reaction, and cytotoxic T lymphocyte (CTL) assays. Apoptotic death in graft-infiltrating cells and in areas of T-dependent lymphoid tissue was visualized by terminal deoxynucleotidyltransferase-catalyzed dUTP-digoxigenin nick-end labeling and quantitative spectrofluorometry. Interleukin-2 production and localization were estimated by immunohistochemistry. RESULTS: Compared with control heart transplantation or heart transplantation after only DC administration, concomitant pretreatment with immature donor DC and anti-CD40L mAb caused sustained elevation of donor (I-Ab+) cells (microchimerism) in the spleen including T cell areas. More than 80% of the I-Ab+ cells in combined treatment animals also were CD86+, reflecting failure of the mAb to inhibit CD40/ CD80/CD86 up-regulation on immature DC in vitro after their interaction with host T cells. Donor-specific CTL activity in graft-infiltrating cells and spleen cell populations of these animals was present on day 8, but decreased strikingly to normal control levels by day 14. The decrease was associated with enhanced apoptosis of graft-infiltrating cells and of cells in the spleen where interleukin-2 production was inhibited. The highest levels of splenic microchimerism were found in mice with long surviving grafts (>100 days). In contrast, CTL activity was persistently elevated in control heart graft recipients with comparatively low levels of apoptotic activity and high levels of interleukin-2. CONCLUSION: The donor-specific acceptance of rejection-prone heart allografts by recipients pretreated with immature donor DC and anti-CD40L mAb is not dependent on sustained inhibition of donor DC CM (CD86) expression. Instead, the pretreatment facilitates a tolerogenic cascade similar to that in spontaneously tolerant liver recipients that involves: (1) chimerism-driven immune activation, succeeded by deletion of host immune responder cells by apoptosis in the spleen and allograft that is linked to interleukin-2 deficiency in both locations and (2) persistence of comparatively large numbers of donor-derived leukocytes. These tolerogenic mechanisms are thought to be generic, explaining the tolerance induced by allografts spontaneously, or with the aid of various kinds of immunosuppression.