ISSN:0892-6638    

DOI:10.1096/fasebj.2.14.3181652

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

A family of unusual DNA structures has been discovered in segments with predominantly purines in one strand (pur · pyr sequences). These sequences are overrepresented in eukaryotic DNA and have been mapped near genes and recombination hot spots. When cloned into recombinant plasmids, many pur · pyr sequences are reactive to chemical and enzymic probes that are generally specific for single‐stranded DNA. An intramolecular triplex is adopted by mirror repeats of G's and A's. Other non‐B DNA structures adopted by similar sequences remain to be fully clarified but may be a family of related conformations. It is likely that these unorthodox structures play an important role in the function of the eukaryotic genome.— Wells, R. D.; Collier, D A.; Hanvey, J. C.; Shimizu, M.; Wohlrab, F.FASEB J.2: 2939‐2949; 1988.

ISSN:0892-6638    

DOI:10.1096/fasebj.2.14.3053307

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

Collagen‐induced arthritis in animals is an example of polyarthritis that sufficiently resembles human rheumatoid arthritis to be used as a model. It is caused by immunizing susceptible animals with type II collagen isolated from articular cartilage. Susceptibility is genetically determined and linked to the major histocompatibility locus. It is important because some human arthritis is also associated with major histocompatibility genes and may be caused or aggravated by the presence of autoimmunity to normal cartilage components. Collagen‐induced arthritis is also important because it is an example of immunologically mediated joint destruction, which may share some of the mechanisms present in human disease. Although it is caused by autoimmunity to collagen, susceptibility and responsiveness to type II collagen are not completely correlated, and there are examples of animals with high levels of collagen immunity who do not develop arthritis. The initial lesion appears to be the deposition of an antibody on the surface of articular cartilage, which precedes development of overt arthritis by several days. Disease can be readily transferred with specific antibody. Arthritogenic antibodies appear to have restricted epitope specificity, which may partially explain the disparities between responsiveness to immunization with collagen and susceptibility to arthritis, but precise delineation of the epitopes involved has not yet been accomplished. Complement activation also appears to be intimately involved since the disease correlates with the presence of high levels of complement‐binding IgG isotypes, and passive transfer is possible only into complement‐sufficient recipients. Inflammation progresses rapidly so that cartilage destruction and marginal erosion develop over a period of a few days. Collagen‐induced arthritis offers a unique opportunity to study autoimmune‐mediated arthritis in which the inducing antigen is well characterized and readily available. Analysis of the disease has permitted the proposal of a schema for its pathogenesis.— Stuart, J. M.; Watson, W. C.; Kang, A. H. Collagen autoimmunity and arthritis.FASEB J.2: 2950‐2956; 1988.

ISSN:0892-6638    

DOI:10.1096/fasebj.2.14.3053308

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

This review focuses on several recent developments in the field of protein kinases. In the area of protein serine/threonine kinases, much has been learned recently about protein kinase C structure and function. Novel lipid mediators, both stimulatory and inhibitory, have been discovered, and kinase has been shown to be an increasingly large family of gene products. Heterogeneity of cellular localization and function has been documented. Calcium/calmodulin‐dependent protein kinases are now believed to consist of at least five enzymes, which range from those with extreme substrate specificity such as phosphorylase kinase and myosin light‐chain kinases to calcium calmodulin kinase II, with several known substrates. Several of these enzymes appear to be important in synaptic transmission and, for calcium/calmodulin kinase III, in the regulation of protein synthesis. Several new examples of pseudosubstrate prototopes as endogenous kinase inhibitors have been described, including regions intrinsic to kinase primary sequences, which could serve as constitutive inhibitors of enzyme activity. In the field of protein tyrosine kinases, new enzyme species are being discovered at a rapid rate. There are several well‐documented examples of kinase autophosphorylation on tyrosine leading to stimulation of catalytic activity. For the growth factor receptors with intrinsic protein tyrosine kinase activity, it now seems clear that kinase catalytic activity is necessary for most hormone effects on cells, with the general exceptions of ligand binding and, possibly, receptor cycling. Finally, several groups have recently described a close association between protein tyrosine kinases and a phosphatidylinositol kinase activity, a link that might eventually explain some of the initial steps in signal transduction that occur after kinase activation.— Blackshear, R J.; Nairn, A. C.; Kuo, J. F. Protein kinases 1988: a current perspective.FASEB J.2: 2957‐2969; 1988.

ISSN:0892-6638    

DOI:10.1096/fasebj.2.14.2972578

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

A variety of diseases of the central and peripheral nervous systems evolves during the course of human immunodeficiency virus (HIV) infections. Most are not related to documented opportunistic infections and may be the direct result of HIV infections, as large proportions of healthy and ill HIV‐infected persons show evidence of nervous system infection. These diseases occur at different times during the infection and have diverse inflammatory, demyelinating, or degenerative pathological features that suggest different pathogenetic mechanisms. The route and determinants of HIV invasion of the nervous system are unknown. Within the brain, viral antigen and RNA are found predominantly in macrophages, but the reason why profound dementia and cortical atrophy result from this infection remains a mystery. By analogy to other lentivirus infections, particularly visna virus in sheep, neuropathological changes may be mediated by cytokines. Other possible pathogenetic mechanisms include toxicity of viral polypeptides, transactivation of viral or cellular genes, autoimmunity, or other opportunistic infections. Clarification of the pathogenesis of HIV‐related diseases is critical to the design of rational therapies.— Johnson, R. T.; McArthur, J. C.; Narayan, O. The neurobiology of human immunodeficiency virus infection.FASEB J.2: 2970‐2981; 1988.

ISSN:0892-6638    

DOI:10.1096/fasebj.2.14.2846395

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

The first three steps of mammalian de novo pyrimidine biosynthesis are catalyzed by the multifunctional protein CAD, consisting of glutamine‐dependent carbamylphosphate synthetase, aspartate transcarbamylase, and dihydroorotase. The intracellular distribution of CAD in two hamster cell lines, BHK 21 and BHK 165‐23 (a strain in which the CAD gene was selectively amplified), was determined by differential centrifugation and by two different cytochemical immunolocalization methods. Ammonia‐dependent carbamylphosphate synthetase I was found in both cell types at a concentration of 0.01% of the total cell protein, so its distribution was also determined as a control for possible cross‐reactivity of the CAD antibody probes and as a mitochondrial marker. CAD was localized in the cytoplasmic compartment and almost completely excluded from the nucleus. A punctate staining pattern suggested that it was not uniformly dispersed throughout the cytosol (unlike typical soluble proteins) but was associated with subcellular organelles. Although there was a slight tendency for CAD to be localized in the vicinity of the nuclear envelope, the amount of staining was much less than expected from differential centrifugation, which showed that 30% of the protein was found in the nuclear fraction. No interactions with other subcellular components could be detected by centrifugation. It is possible, however, that CAD is associated with subcellular structures that cosediment with the nuclei. Despite a 150‐fold increase in CAD concentration in the over‐producing cells, the distribution of the protein was unaltered. CAD was not concentrated near the mitochondria where the next enzyme of the de novo pathway, dihydroorotate dehydrogenase, is localized, which indicates that the intermediate dihydroorotate is not channeled, but rather dissociates from CAD and diffuses through the bulk cellular fluid.— Chaparian, M. G.; Evans, D. R. Intracellular location of the multi‐domain protein CAD in mammalian cells.FASEB J.2: 2982‐2989; 1988.

ISSN:0892-6638    

DOI:10.1096/fasebj.2.14.2903106

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

There is increasing evidence that the use of cocaine can trigger lethal cardiac events, including ventricular fibrillation. The mechanism responsible for these lethal cardiac arrhythmias remains to be determined. Therefore, 13 mongrel dogs were instrumented so that heart rate, left ventricular pressure (LVP), and d(LVP)/dt could be measured. After a 3‐ to 4‐wk recovery period, the left circumflex coronary artery was occluded for 2 min, beginning with the last minute of an exercise stress test and continuing for 1 min after the cessation of exercise. None of the dogs developed cardiac arrhythmias during the control exercise plus ischemia test. On a subsequent day, the test was. repeated after the injection of cocaine HCl (1.0 mg/kg). Cocaine significantly (P<0.01) elevated heart rate, systolic LVP, and d(LVP)/dt, and it elicited cardiac arrhythmias in 12 of the 13 animals during the exercise plus test. In fact, 11 animals developed ventricular fibrillation. Verapamil, a calcium channel antagonist (250 μg/kg), attenuated the hemodynamic effects of cocaine and prevented the development of ventricular arrhythmias. These data suggest that cocaine can induce ventricular fibrillation during myocardial ischemia and that these lethal arrhythmias may be prevented by a calcium channel antagonist.— Billman, G. E.; Hoskins, R. S. Cocaine‐induced ventricular fibrillation: protection afforded by the calcium antagonist verapamil.FASEB J.2: 2990‐2995; 1988.

ISSN:0892-6638    

DOI:10.1096/fasebj.2.14.3181653

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

The relationship of whole blood selenium (Se) to glutathione peroxidase (GPX) activity was examined for individuals in New Zealand, Oregon, and South Dakota who represented, respectively, populations with exposure to low, medium, and high amounts of Se. The mean (respective) blood Se levels were 60, 200, and 400 ng/ml. Intergroup differences in blood Se levels were highly significant (P<0.001). GPX assays were performed using two variations of an enzyme‐coupled procedure to assess the equivalence of the two methods. Despite a fourfold difference in absolute activities measured by these methods, the GPX activities were highly correlated (r= .86) between procedures. Average blood GPX activity was significantly lower (P<0.001) for the New Zealand group compared with the other two groups, but there was no difference in GPX activities between the Oregon and South Dakota groups. Linear regression of GPX vs. Se values within each group indicated a significant correlation of these parameters only in the New Zealand group (r= .46,P<0.01). Comparison of these parameters for combined data from all three groups also showed a significant positive correlation (r= .60,P<0.001). A saturation model (ln GPX = k1+k2(Se)−1] fits the combined data better (r= .80,P<0.01) than does direct comparison of the two parameters. These results suggest that GPX activity is an appropriate indicator of human Se status only in populations with below normal exposure to Se, as activity of this enzyme is saturated at relatively low levels.—Whanger, P. D.; Beilstein, M. A.; Thomson, C. D.; Robinson, M. F.; Howe, M. Blood selenium and glutathione peroxidase activity of populations in New Zealand, Oregon, and South Dakota.FASEB J.2: 2996‐3002; 1988.

ISSN:0892-6638    

DOI:10.1096/fasebj.2.14.3181654

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

In this paper we outline a flexible and rapid method to measure picogram quantities of isotype‐specific immunoglobulin (Ig), including IgE. Only readily or commercially available reagents are required: isotypespecific, anti‐human Ig murine monoclonal antibodies (Mab) to coat microtiter plates, polyclonal alkaline phosphatase‐coupled isotype‐specific F(ab)‘2 or Fab’ fragments as second antibodies, and an enhanced developing system that amplifies the signal‐to‐noise ratio of the quantitatively bound second antibody. The procedure is detailed in the appendix to enable easy application, even if one has no previous experience with ELISAs. This system can be used to detect less than 10 picograms of Ig in cultures supernatants of cells that contain mixtures of various Igs and it can be used to detect the product of a single cell producing Ig. This method also will be applicable to measurement of the minute quantities of lymphokines and other biologically active molecules produced in vitro and found in various fluids in vivo.—Macy, E.; Kemeny, M.; Saxon, A. Enhanced ELISA: How to measure less than 10 picograms of a specific protein (immunoglobulin) in less than 8 hours.FASEB J.2: 3003‐3009; 1988.

ISSN:0892-6638    

DOI:10.1096/fasebj.2.14.3263291

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

A cDNA coding for the catalytic subunit of phosphorylase phosphatase (phosphatase C‐I/phosphatase‐lc) was cloned from a rabbit muscle cDNA library by screening with oligonucleotide probes. Ten clones were analyzed. The full cDNA sequence of 1395 base pairs contained an open reading frame of 990 base pairs flanked by 3' and 5' noncoding regions of 84 and 321 base pairs, respectively. The DNA sequence (and deduced amino acid sequence) of this cDNA is distinctly different from that of a clone of 1492 base pairs previously reported. Our cDNA is essentially identical to the 1492‐base pair clone from residue 182 in the 3' direction, but it is completely different in the 5' direction. Consequently, the amino acid sequence deduced from our cDNA differs by 14 amino acids in the amino terminal from that previously reported and extends for an additional 19 amino acids. Probes to the divergent and common region of our cDNA clone hybridized to an mRNA of the same size by Northern blotting. Thus the cDNA we have isolated appears to code for an isoform of the catalytic subunit of phosphorylase phosphatase.—Bai, G.; Zhang, Z.; Amin, J.; Deans‐Zirattu, S. A.; Lee, E. Y. C. Molecular cloning of a cDNA for the catalytic subunit of rabbit muscle phosphorylase phosphatase.FASEB J.2: 3010‐3016; 1988.

ISSN:0892-6638    

DOI:10.1096/fasebj.2.14.2846396

出版商:Wiley    

年代:1988

数据来源: WILEY