Autoregulation of contractility in the myocardial cell

Summary An investigation was carried out on isolated cat's papillary muscle in order to study displacement effects upon the intensity and the time course of the contractile activity. Displacements occurring before or very early during a contractile cycle produce effects which can be entirely explained on the basis of the cardiac active length-tension relation. Displacements occurring later exhibit additional effects in so far as either stretches or releases induce a drop of contractile activation such that the course of the subsequent tension development is markedly below that of the same displacement applied earlier. In order to separate these effects from those based on the active length-tension correlation experiments were performed in which very short release-stretch or stretch-release operations were applied so that the muscle length was virtually the same at the beginning and at the end of the operation. The results obtained under these conditions can be summarized as follows.The extend to which contractile tension drops after a stretch-release or a release-stretch cycle has been applied depends upon (1) the stimulus intervention interval (2) the length change performed (3) the velocity of displacement during the intervention. It is not dependent on the initial muscle length. Increasing the extracellular Ca-concentration considerably reduces the displacement effects. The results are tentatively explained by assuming an internal feedback loop between a variable of the contractile machinary and the preceding mechanism of activation.This investigation was supported by the Deutsche Forschungsgemeinschaft (grant Ka 287, 1+3).     

Human smooth pursuit during transient perturbations of predictable and unpredictable target movement

Summary The predictive component of human smooth pursuit was studied by perturbing sinusoidal target motion at unpredictable instants. The disturbances consisted of either a brief period of stabilization of the target on the fovea or a replacement of the sine by a ramp displacement for half a period. To minimize the effects of a possible change of the tracking strategy by the subject the transitions were masked and only the initial part of the response to the disturbance was analyzed. After stabilization on the fovea the eye oscillation continued at the frequency of the preceding target movement for about one half-cycle, whereupon the oscillation was rapidly damped. The mean unidirectional smooth eye acceleration was 70% of the mean unidirectional target acceleration prior to the stabilization. This suggests that during pursuit of a sinusoidal target movement about 75% of the oculomotor response is generated by predictive processes. When the sine was replaced by a ramp, starting at the velocity zero-crossing, the eye accelerated away from the target for ca. 180 ms irrespective of the frequency of prior tracking. In contrast, when the ramp started at the peak velocity of the sinusoidal target motion the eye accelerated away from the target for more than a quarter period. After foveal stabilization during pursuit of a pseudorandom stimulus, the eye continued to oscillate for less than one period at approximately the highest frequency present in the stimulus. The frequency characteristics of human smooth pursuit of predictable as well as unpredictable target motion were correctly simulated by a model, which derived its predictive properties from a lead element, tuned to the current frequency of the target motion.     

Structural diversity among anti-p-azophenylarsonate monoclonal antibodies from A/J mice: Comparison of Id and Id sequences

Amino acid sequence analyses were carried out on monoclonal anti-p-azophenylarsonate antibodies isolated from the ascites of mice carrying cell lines obtained from the fusion of A/J splenic lymphocytes with the myeloma cell line Sp2/0–Ag14. The partial primary structures of both heavy and light chains from seven idiotype negative hybridoma proteins are compared to those of six idiotype positive molecules. Amino-terminal amino acid sequences (40–47 residues) of heavy chains from molecules bearing the major cross-reacting idiotype, Id^CR, demonstrated 95% homology to each other. Similarly, aminoterminal sequences of Id^CR+light chains were homologous to each other. However, sequence variations were evident in individual antibodies in both framework and complementarity-determining regions, suggesting that a large family of molecules accounts for the major cross-reacting idiotype, as previously reported (Marshak-Rothstein et al., 1980b).

Heavy and light chains from seven Id^CR-negative monoclonal antibodies were subjected to amino-terminal (37–48 residues) amino acid sequence analysis. Four heavy chains were blocked to Edman degradation, but could be sequenced after enzymatic removal of the amino-terminal pyrrolidone carboxylic acid residue. In comparison with Id^CR-positive heavy chains, the Id^CR-negative heavy chains demonstrate greater diversity in both framework and complementarity-determining regions, with several different subgroups represented in contrast to the results from pooled serum Id^CR-positive antibodies (Capra et al., 1975). One of the seven Id^CR-negative light chains was blocked. The sequences of the remaining Id^CR-negative light chains exhibited marked variations in both framework and complementarity-determining regions, with different chain lengths in the first complementarity-determining region in several light chains.

Comparisons between the amino-terminal sequences of Id^CR-positive and Id^CR-negative monoclonal antibodies suggest that specific sequences in the first complementarity-determining regions of both heavy and light chains are not sufficient to account for the major cross-reacting idiotype. The structural basis for Id^CR in A/J mice is likely to be in other segments of the variable regions.     

Binding of Cellular Proteins to the Leader RNA of Equine Arteritis Virus

The genome of equine arteritis virus (EAV) produces a 3 coterminal-nested set of six subgenomic (sg) viral RNAs during virus replication cycle, and each set possesses a common leader sequence of 206 nucleotides (nt) in length derived from the 5 end of the viral genome. Given the presence of the leader region within both genomic and sg mRNAs, it is likely to contain cis-acting signals that may interact with cellular or viral proteins for RNA synthesis. Gel mobility shift assays indicated that proteins in Vero cell cytoplasmic extracts formed complexes with the positive (+) and negative (-) strands of the EAV leader RNA. Several cell proteins with molecular masses ranging from 74 to 31 kDa and 58 to 32 kDa were detected in UV-induced cross-linking assays with the EAV leader RNA (+) and (-) strands, respectively. In both cases, intense bands were observed at the 58–52 kDa molecular weight markers. Results from competition gel mobility shift assays using overlapping cold RNA probes spanning the leader RNA (+) strand indicated that nt 140–206 are not necessary for binding to cell proteins.     

An enzyme-linked immunosorbent assay (ELISA) for the measurement of antibodies to different parts of the gram-negative lipopolysaccharide core region

Bovine serum albumin was complexed with the core antigens of either Escherichia coli J5 LPS, Salmonella minnesota R595 LPS or E. coli lipid A. These core-BSA complexes were used for solid-phase coating in ELISAs for anti-core antibodies. Antibodies, binding to various parts of the core region were easily quantified in a single experimental set-up, which was hitherto not possible. The ELISA has only 3 incubation steps and is not costly as only moderate amounts of the core antigens (i.e., 1 microgram per test) were needed for coating. The sensitivity proved to be excellent and the complexes were biologically fully active (compared to native, smooth LPS), which make them suitable for the screening (after fusion) of monoclonal anti-core antibodies. Another possible application is the large-scale screening of blood-bank sera in order to find samples with a high anti-core antibody content.     

增殖细胞核抗原表达与AgNORs图像分析在判断肺癌预后上的应用

应用抗增殖细胞核抗原（抗ＰＣＮＡ）单克隆抗体，采用Ｓ－Ｐ免疫组化方法和ＡｇＮＯＲｓ染色图像分析，对有确切随访结果的８６例原发性肺癌和１０例肺炎性假瘤进行了研究。结果表明：经ＰＣ－ＮＡ阳性反应计算出的增殖指数（ＰＩ）与图像分析的ＡｇＮＯＲｓ计数及其颗粒总面积间存在着明显的相关性。二者均与肺癌分型有关，并随癌分化程度的增高而减小；与ＴＮＭ分期中的淋巴结（Ｎ）和远隔转移（Ｍ）有关；术后存活５年以上者明显小于３年以内者（Ｐ＜０．０１）。认为ＰＣＮＡ的表达和ＡｇＮＯＲｓ图像分析技术有助于肺癌的分型、分化及预后的判断。     

抗人C1—抑制物单链抗体的构建

由一株抗人Ｃ１－抑物单克隆抗体鼠杂交瘤细胞提取总ＲＮＡ，合成２对与免疫蛋白可变区ＦＲ１和ＦＲ４互补的通用引物，经ＲＴ－ＰＣＲ扩增出抗体的重链可变区和轻链可变区基因。     

Separate and variably shaped chromosome arm domains are disclosed by chromosome arm painting in human cell nuclei

Fluorescence in situ hybridization (FISH) with microdissection probes from human chromosomes 3 and 6 was applied to visualize arm and subregional band domains in human amniotic fluid cell nuclei. Confocal laser scanning microscopy and quantitative three-dimensional image analysis showed a pronounced variability of p- and q-arm domain arrangements and shapes. Apparent intermingling of neighbouring arm domains was limited to the domain surface. Three-dimensional distance measurements with pter and qter probes supported a high variability of chromosome territory folding.