The FREP gene family in the snail Biomphalaria glabrata: additional members,and evidence consistent with alternative splicing and FREP retrosequences. Fibrinogen-related proteins

Fibrinogen-related proteins (FREPs) found in hemolymph of the snail Biomphalara glabrata are hypothesized to be involved in non-self recognition. Among 150 cloned FREP cDNAs examined, we have identified three additional FREP members, FREPs 3.3, 12.1 and 13.1, bringing the total of FREP subfamilies to 13. The new FREPs each encode two immunoglobulin superfamily domains and a fibrinogen domain. Additionally, five truncated cDNAs with >99% nucleotide identity in coding regions to FREPs 3.2, 12.1 or 13.1 were identified. The truncated forms, the first reported for FREPs, lack a partial exon, one complete exon, or two complete exons plus the 3'UTR. Our preferred hypothesis is that all five truncated cDNAs observed arise from alternative splicing of full-length FREP genes. Genomic sequences lacking at least two introns and corresponding to the 3' ends of the cDNAs of FREP12.1 and its two truncated forms were also recovered. Although these could be the source of the truncated cDNAs, they are believed to be retrosequences.     

Reversible blockade of experience-dependent plasticity by calcineurin in mouse visual cortex

Numerous protein kinases have been implicated in visual cortex plasticity, but the role of serine/threonine protein phosphatases has not yet been established. Calcineurin, the only known Ca2+/calmodulin-activated protein phosphatase in the brain, has been identified as a molecular constraint on synaptic plasticity in the hippocampus and on memory. Using transgenic mice overexpressing calcineurin inducibly in forebrain neurons, we now provide evidence that calcineurin is also involved in ocular dominance plasticity. A transient increase in calcineurin activity is found to prevent the shift of responsiveness in the visual cortex following monocular deprivation, and this effect is reversible. These results imply that the balance between protein kinases and phosphatases is critical for visual cortex plasticity.     

Latent variable discovery in classification models

The naive Bayes model makes the often unrealistic assumption that the feature variables are mutually independent given the class variable. We interpret a violation of this assumption as an indication of the presence of latent variables, and we show how latent variables can be detected. Latent variable discovery is interesting, especially for medical applications, because it can lead to a better understanding of application domains. It can also improve classification accuracy and boost user confidence in classification models.     

Diagnostic imaging of breast cancer using fluorescence-enhanced optical tomography: phantom studies

Molecular targeting with exogenous near-infrared excitable fluorescent agents using time-dependent imaging techniques may enable diagnostic imaging of breast cancer and prognostic imaging of sentinel lymph nodes within the breast. However, prior to the administration of unproven contrast agents, phantom studies on clinically relevant volumes are essential to assess the benefits of fluorescence-enhanced optical imaging in humans. Diagnostic 3-D fluorescence-enhanced optical tomography is demonstrated using 0.5 to 1 cm(3) single and multiple targets differentiated from their surroundings by indocyanine green (micromolar) in a breast-shaped phantom (10-cm diameter). Fluorescence measurements of referenced ac intensity and phase shift were acquired in response to point illumination measurement geometry using a homodyned intensified charge-coupled device system modulated at 100 MHz. Bayesian reconstructions show artifact-free 3-D images (3857 unknowns) from 3-D boundary surface measurements (126 to 439). In a reflectance geometry appropriate for prognostic imaging of lymph node involvement, fluorescence measurements were likewise acquired from the surface of a semi-infinite phantom (8x8x8 cm(3)) in response to area illumination (12 cm(2)) by excitation light. Tomographic 3-D reconstructions (24,123 unknowns) were recovered from 2-D boundary surface measurements (3194) using the modified truncated Newton's method. These studies represent the first 3-D tomographic images from physiologically relevant geometries for breast imaging.     

SK&F 95654-induced acute cardiovascular toxicity in Sprague-Dawley rats--histopathologic, electron microscopic, and immunohistochemical studies

The characteristics and pathogenesis of the cardiovascular toxicity induced by the type III selective phosphodiesterase inhibitor SK&F 95654 were examined in 2 studies. Sprague-Dawley rats received either a single sc injection of 50, 100, or 200 mg/kg SK&F 95654 and were euthanized at 24 hours after administration of the drug (Study 1), or were given a single subcutaneous (sc) injection of 100 mg/kg SK&F 95654 and euthanized at 1, 2, 4, 6, 8,12, 24 hours, or 2 weeks after treatment (Study 2). Control rats received either DMSO or saline. Myocardial lesions and vascular lesions of the mesentery, spleen, and pancreas were seen 24 hours after dosing with either 50,100, or 200 mg/kg SK&F 95654. The frequency and severity of these lesions (evaluated after the 100 mg/kg dose) increased with time over a period of 1 to 24 hours. By 2 weeks, the lesions subsided. Cardiac lesions consisted of myocyte necrosis with hypercontraction bands, inflammatory cell infiltration, interstitial hemorrhage, and interstitial edema. Vascular lesions of the mesentery were most prominent and consisted of vasodilatation and inflammation in the small-sized vessels, arterial medial necrosis and hemorrhage, and venous thrombosis. The vascular lesions included: leukocyte adhesion to endothelial cells, transendothelial migration of leukocytes, and inflammatory cell infiltration into vessel walls. Affected vessels included arteries, terminal arterioles, capillaries, postcapillary venules, and veins. Apoptosis of endothelial and smooth muscle cells was detected in the mesenteric vasculature by both TUNEL assay and electron microscopy. Evidence of endothelial cell activation in the mesenteric arteries and veins was also observed by electron microscopy. Immunohistochemical staining detected enhanced endothelial cell expression of intercellular adhesion molecule- 1 (ICAM- 1) and von Willebrand factor (vWF) in the mesenteric arteries and veins. Mast cells were noted to be more prevalent in affected mesenteric tissue from drug-treated animals. The present findings suggest that apoptosis of endothelial and smooth muscle cells, activation of endothelial cells, recruitment of mast cells, and increased expression of adhesion molecules are important factors to the overall pathogenesis of SK&F 95654-induced vasculitis.     

Differentiation of Cucumber mosaic virus isolates by hybridization to oligonucleotides in a microarray format

A system for microarrays was developed to detect and differentiate Cucumber mosaic virus (CMV) serogroups and subgroups. The coat protein genes of 14 different isolates were amplified using cy3-labelled generic but species-specific primers. These amplicons were hybridized against a set of five different serotype and subgroup specific 24-mer oligonucleotides bound to an aldehyde-coated glass slide via an aminolinker. The results of the hybridization revealed that the method allowed a clear differentiation of the 14 different CMV isolates into the serogroupes 1 and 2, and in addition was able to assign 9 out of 10 different serogroup 1 isolates correctly into subgroups 1a and 1b. This differentiation was not possible by RFLP analysis with the restriction enzyme MspI. The use of amplicons larger than 700 base pairs and their successful differentiation by hybridization to specific oligonucleotides opens avenues to highly parallel, yet sensitive assays for plant viruses.     

Temporal profile of potassium channel dysfunction in cerebrovascular smooth muscle after experimental subarachnoid haemorrhage

The pathogenesis of cerebral vasospasm after subarachnoid haemorrhage (SAH) involves sustained contraction of arterial smooth muscle cells that is maximal 6–8 days after SAH. We reported that function of voltage-gated K⁺ (K_V) channels was significantly decreased during vasospasm 7 days after SAH in dogs. Since arterial constriction is regulated by membrane potential that in turn is determined predominately by K⁺ conductance, the compromised K⁺ channel dysfunction may cause vasospasm. Additional support for this hypothesis would be demonstration that K⁺ channel dysfunction is temporally coincident with vasospasm. To test this hypothesis, SAH was created using the double haemorrhage model in dogs and smooth muscle cells from the basilar artery, which develops vasospasm, were isolated 4 days (early vasospasm), 7 days (during vasospasm) and 21 days (after vasospasm) after SAH and studied using patch-clamp electrophysiology. We investigated the two main K⁺ channels (K_V and large-conductance voltage/Ca²⁺-activated (K_Ca) channels). Electrophysiologic function of K_Ca channels was preserved at all times after SAH. In contrast, function of K_V channels was significantly decreased at all times after SAH. The decrease in cell size and degree of K_V channel dysfunction was maximal 7 days after SAH. The results suggest that K_V channel dysfunction either only partially contributes to vasospasm after SAH or that compensatory mechanisms develop that lead to resolution of vasospasm before K_V channels recover their function.     

人皮肤内神经-肥大细胞联接在经络线上的发现 Ⅱ“传入性”神经-肥大细胞联接和伴同传出性轴突的薛旺细胞

本研究取材于人的皮肤,电镜常规方法处理。发现人皮肤内有两种类型的神经肥大细胞联接。提示可能分别为传出性和传入性的,或暂称为A型和B型联接,分别报告于上篇和本篇中。 B型联接的构造特点是,脱开薛旺鞘样长带包被的轴突来到肥大细胞近旁,突进细胞体中。轴突终末的一部分被胞质唇封盖起来,终末周围的轴膜与细胞质膜形成联接的双层膜。无肥大细胞表面皱褶参与其形成,无线粒体和显明的囊泡存在终末之内,无薛旺细胞包被轴突终末。薛旺细胞伴同A型联接出现,可与肥大细胞紧密接触。胞质内有狭缝系统和粗面内质网片断,能拖出长尾,估计将过渡为鞘膜。薛旺细胞不是间织细胞,这里的间织细胞应是成纤维细胞。