The occipitoparietal pathway of the macaque monkey: comparison of pyramidal cell morphology in layer III of functionally related cortical visual areas

The dendritic morphology of pyramidal cells located at the base of layer III in the primary visual area (V1), the second visual area (V2), the middle temporal area (MT), the ventral portion of the lateral intraparietal area (LIPv) and in the portion of cytoarchitectonic area 7a within the anterior bank of the superior temporal sulcus was revealed by injecting neurons with Lucifer Yellow in fixed, flattened slices of macaque monkey visual cortex. These areas correspond to different levels of the occipitoparietal cortical 'stream', which processes information related to motion and spatial relationships in the visual field. The tissue was immunocytochemically processed to obtain a light-stable diaminobenzidine reaction product, revealing the dendritic morphology in fine detail. Retrogradely labelled MT- projecting neurons in supragranular V1 (layer IIIc of Hassler's nomenclature, corresponding to Brodmann's layer IVb) were predominantly pyramidal, although many spiny multipolar (stellate) cells were also found. The average basal dendritic field area of pyramidal neurons in sublamina IIIc of V1 was significantly smaller than that in the homologous layer of V2, within the cytochrome oxidase-rich thick stripes. Furthermore, the average basal dendritic field areas of V1 and V2 pyramidal neurons were significantly smaller than those of neurons in MT, LIPv and area 7a. There was no difference in basal dendritic field area between layer III pyramidal neurons in areas MT, LIPv and 7a. While the shape of most basal dendritic fields was circularly symmetrical in the dimension tangential to the cortical layers, there were significant biases in complexity, with dendritic branches tending to cluster along particular axes. Sholl analysis revealed that the dendritic fields of neurons in areas MT, LIPv and 7a were significantly more complex (i.e. had a larger number of branches) than those of V1 or V2 neurons. Analysis of basal dendritic spine densities revealed regional variations along the dendrites, with peak densities being observed 40-130 microns from the cell body, depending on the visual area. The peak spine density of layer III pyramidal neurons in V1 was lower than that observed in V2, MT or LIPv, which were all similar. Pyramidal neurons in area 7a had the greatest peak spine density, which was on average 1.7 times that found in V1. Calculations based on the average spine density and number of dendritic branches at different distances from the cell body demonstrated a serial increase in the total number of basal dendritic spines per neuron at successive stations of the occipitoparietal pathway. Our observations, comparing dendritic fields of neurons in the homologous cortical layer at different levels of a physiologically defined 'stream', indicate changes in pyramidal cell morphology between functionally related areas. The relatively large, complex, spine-dense dendritic fields of layer III pyramidal cells in rostral areas of the occipitoparietal pathway allow these cells to sample a greater number of more diverse inputs in comparison with cells in 'lower' areas of the proposed hierarchy.      

The prevalence of HFE C282Y gene mutation is increased in Spanish patients with porphyria cutanea tarda without hepatitis C virus infection

OBJECTIVES: To investigate the role of C282Y and H63D mutations, and hepatitis C virus (HCV) infection in the pathogenesis of porphyria cutanea tarda (PCT). DESIGN: Prospective case-control study. SETTING: A large clinical and research institute for the study and treatment of cutaneous diseases in Barcelona, Spain. PATIENTS: Ninety-nine consecutive patients with PCT and one hundred and twenty-six control patients (76 healthy subjects and 50 patients chronically infected with HCV), were recruited. MAIN OUTCOME MEASURES: The frequency of the C282Y and H63D mutations in patients with PCT vs. controls and the relationship of these mutations with HCV infection, and iron status, as judged by serum iron, liver iron and ferritin levels. RESULTS: C282Y mutation was significantly increased in PCT patients. This mutation was more frequent among non-HCV-infected patients. Increased ferritin levels and hepatic iron overload were also observed in PCT patients with heterozygous C282Y state. H63D mutation was only significantly increased among PCT patients with chronic hepatitis C infection. No significant iron overload was observed in patients with H63D mutation. CONCLUSIONS: This study confirms the high frequency of C282Y mutation in patients with PCT and its relationship with iron overload. The C282Y mutation has a relevant role in Spanish patients with PCT not associated with HCV chronic infection. On the other hand, the prevalence of the H63D mutation seems not to be increased in patients with PCT. The possibility of an association between HCV infection and H63D mutation in inducing PCT can be hypothesized.     

Molecular basis and expression of the LWa/LWb blood group polymorphism

The Landsteiner-Wiener (LW) blood group antigens reside on a 42-kD erythrocyte membrane glycoprotein that has recently been cloned. Here, we found that the molecular basis for the LWa/LWb polymorphism is determined by a single base pair mutation (A308G) that correlates with a Pvu II restriction site and results in a Gln70Arg amino acid substitution. COS-7 cells transfected with LWa or LWb cDNAs reacted with human anti-LWa and anti-LWb sera, respectively, as well as with a murine monoclonal anti-LWab antibody, as shown by flow cytometry analysis. Moreover, a 42-kD protein was immunoprecipitated from the transfected cells with the monoclonal anti-LWab antibody. These findings indicate that LWa and LWb are alleles of the LW blood group locus as defined also by a monoclonal anti-LWab of nonhuman origin. In addition, the LW locus has been assigned to chromosome 19p13.3 by in situ hybridization. Study by Southern blot analysis indicated also that the LW locus is composed of a single gene that was not grossly rearranged in rare LW(a-b-) and Rhnull individuals deficient for LW antigens. In addition, Pvu II restriction fragment-length polymorphism analysis indicated that these variants were all homozygous for a phenotypically silent LWa allele.     

越快越好—事实就是如此(摘要)

随着一次次在拥有大量听众的演讲、会议上以及许多学术杂志中谈论床旁检测实验 (ｐｏｉｎｔ ｏｆ ｃａｒｅｔｅｓｔｉｎｇ,ＰＯＣＴ) ,实验室检验人员正面对如何应用和管理ＰＯＣＴ这一问题。迄今为止 ,真正认真对ＰＯＣＴ的价值做了严肃研究的文献仍属凤毛麟角。Ｎｉｃｈｏｌｓ等发表的文章论述了应用ＰＯＣＴ如何使心血管病人等候的时间缩短。这提供了应用ＰＯＣＴ前如何缜密思考的一个例子。他们事先探讨了ＰＯＣＴ的最佳设置地点 ,如何使用ＰＯＣＴ ,如何计算测定费用 ,以及如何处理与病人的关系和工作流程 ,以使ＰＯＣＴ的应用尽可能简…