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S Ren TF Kalhorn GB McDonald C Anasetti FR Appelbaum JT Slattery 《Canadian Metallurgical Quarterly》1998,64(3):289-301
Classical swine fever virus infection of pigs causes a severe leukopenia and immunosuppression. In the present study, the kinetics of virus infection, and identification of target cells for the virus in peripheral blood were analysed. Virus infection was often not detectable before 5-7 days p.i. A minority of animals yielded detectable infected cells at 3 days p.i., but < 5% PBMC. It was not until 10 days p.i. that this figure increased-to 35-70% PBMC depending on the animal. Detailed analysis of Ficoll-Hypaque-purified PBMC identified the major population to be SWC3+SWC8+CD14+MHCII- granulocytic cells. Microscopic observations determined that these low density granulocytic cells in the PBMC from CSFV infected animals were indeed immature cells. Both the low density granulocytic cells and monocytes were major targets for CSFV infection in the peripheral blood. This is the first demonstration that low density granulocytic cells dominate the blood leukocyte population during CSF, and that such cells are targets for virus infection. The present work also demonstrates that the leukocyte population changes, such as B lymphocyte depletion and the relative dominance of myeloid cells in the blood during CSF, occur before virus infection of the affected cells. Thus, the pathological mechanism therein is not a direct consequence of virus infection. 相似文献
45.
Y Zhu M Carroll FR Papa M Hochstrasser AD D'Andrea 《Canadian Metallurgical Quarterly》1996,93(8):3275-3279
Cytokines regulate cell growth by inducing the expression of specific target genes. Using the differential display method, we have cloned a cytokine-inducible immediate early gene, DUB-1 (for deubiquitinating enzyme). DUB-1 is related to members of the UBP superfamily of deubiquitinating enzymes, which includes the oncoprotein Tre-2. A glutathione S-transferase-DUB-1 fusion protein cleaved ubiquitin from a ubiquitin-beta-galactosidase protein. When a conserved cysteine residue of DUB-1, required for ubiquitin-specific thiol protease activity, was mutated to serine (C60S), deubiquitinating activity was abolished. Continuous expression of DUB-1 from a steroid-inducible promoter induced growth arrest in the G1 phase of the cell cycle. Cells arrested by DUB-1 expression remained viable and resumed proliferation upon steroid withdrawal. Our results suggest that DUB-1 regulates cellular growth by modulating either the ubiquitin-dependent proteolysis or the ubiquitination state of an unknown growth regulatory factor(s). 相似文献
46.
L Kohl T Drmota CD Thi M Callens J Van Beeumen FR Opperdoes PA Michels 《Canadian Metallurgical Quarterly》1996,76(1-2):159-173
A polyclonal antiserum raised against the purified glycosomal glycerol-3-phosphate dehydrogenase of Trypanosoma brucei brucei has been used to identify the corresponding cDNA clone in a T.b. brucei expression library. This cDNA was subsequently used to obtain genomic clones containing glycerol-3-phosphate dehydrogenase genes. Two tandemly arranged genes were detected in these clones. Characterization of one of the genes showed that it codes for a polypeptide of 353 amino acids, with a molecular mass of 37,651 Da and a calculated net charge of +8. Using the T.b. brucei gene as a probe, a corresponding glycerol-3-phosphate dehydrogenase gene was also identified in a genomic library of Leishmania mexicana mexicana. The L.m. mexicana gene codes for a polypeptide of 365 amino acids, with a molecular mass of 39,140 Da and a calculated net charge of +8. The amino-acid sequences of both polypeptides are 63% identical and carry a type-1 peroxisomal targeting signal (PTS1) SKM and -SKL at their respective C-termini. Moreover, the L.m. mexicana polypeptide also carries a short N-terminal extension reminiscent of a mitochondrial transit sequence. Subcellular localisation analysis showed that in L.m. mexicana the glycerol-3-phosphate dehydrogenase activity co-fractionated both with mitochondria and with glycosomes. This is not the case in T. brucei, where the enzyme is predominantly glycosomal. The two trypanosomatid sequences resemble their prokaryotic homologues (32-36%) more than their eukaryotic counterparts (25-31%) and carry typical prokaryotic signatures. The possible reason for this prokaryotic nature of a trypanosomatid glycerol-3-phosphate dehydrogenase is discussed. 相似文献
47.
PG Matz SM Massa PR Weinstein C Turner SS Panter FR Sharp 《Canadian Metallurgical Quarterly》1996,85(5):892-900
Induction of the hemeoxygenase-1 (ho-1) stress gene is of importance for rapid heme metabolism and protection against oxidative injury in vitro and in vivo. Although ho-1 expression is observed in glia following exposure to whole blood and oxyhemoglobin, expression is mild, and other stress genes are not induced simultaneously in this setting. Hemeoxygenase-1 can be induced by several other physiological stresses in addition to heme. In the brain, ho-1 induction has been observed in the penumbra following focal cerebral ischemia. Because lysed blood is a spasmogen, the authors studied focal hyperexpression of the ho-1 gene after injection of lysed blood, whole blood, or saline into the cisterna magna of adult rats. Immunocytochemical analysis of HO-1 was performed at 1, 2, 3, and 4 days after the injections. Because the 70-kD inducible heat shock protein (HSP70) is induced by cellular stress, alternate sections were immunostained for HSP70 to assess whether focal hyperexpression was a stress phenomenon. An oligonucleotide probe was also used for in situ hybridization to demonstrate that ho-1 messenger (m)RNA was present. Focal HO-1 immunostained areas were observed after lysed blood injection only and were located mainly in the basal cortex and cerebellar hemisphere, although focal hyperexpression was also found in many other regions. The intensity of staining and the number of regions were maximum at 1 day. Double-labeled immunofluorescence revealed that many HO-1-immunoreactive cells were microglia. The HSP70 immunostaining of adjacent sections from the same animals demonstrated focal regions of immunoreactivity whose topography corresponded exactly with the topography of the HO-1-immunostained areas. Conventional histology in regions of HO-1 hyperexpression was often normal. In situ hybridization using the same oligonucleotide demonstrated that ho-1 mRNA was induced in focal areas of forebrain and in large regions of cerebellum within 6 hours of injection. These results demonstrate that focal hyperexpression of the ho-1 stress gene occurs after lysed blood injection and appears to be an indicator of cellular stress and injury in regions in which infarction does not occur. These results also suggest that cellular injury that occurs after injection of lysed blood may go undetected using conventional histology. Although direct heme metabolism was not investigated, our results indicate that rapid metabolism of heme, both intracellular and extracellular, may prove to be beneficial after subarachnoid hemorrhage. 相似文献
48.
AS Piatek S Tyagi AC Pol A Telenti LP Miller FR Kramer D Alland 《Canadian Metallurgical Quarterly》1998,16(4):359-363
Strictureplasty for treatment of symptomatic intestinal strictures secondary to Crohn's disease is being performed with increasing frequency. To determine the overall clinical results after strictureplasty for Crohn's disease, all patients undergoing this procedure were prospectively studied. Between 6/1/89 and 2/1/97, 57 Crohn's disease patients underwent 60 operations utilizing strictureplasties. A total of 109 strictureplasties were performed (90 Heineke-Mikulicz, 6 Finney, and 13 side-to-side isoperistaltic). The 30-day perioperative morbidity was 12%, with complications being less common for patients undergoing elective versus unscheduled operations (p < 0.002). Recurrence of Crohn's disease requiring operation was seen in seven patients after a mean follow-up of 38 months. The estimated cumulative recurrence rate after 2 years was 15 +/- 6% (+/- standard error) and 22 +/- 10% at 5 years. A recurrence developed at the site of the previous strictureplasty in only five cases. Strictureplasty is a safe, effective means of providing long-term surgical palliation to selected patients with Crohn's disease. Perioperative complication rates are comparable to those seen with standard surgical treatment, and recurrences are not excessive. 相似文献
49.
DA Flanagan SB Gladding FR Lovell 《Canadian Metallurgical Quarterly》1998,64(7):670-2; discussion 673
99Tc-sestamibi prone scintimammography (SMM) is a new, noninvasive method of imaging breast tumors. A pilot study has suggested that SMM increases the specificity of mammography, and that SMM could be used as an adjunct to mammography to reduce the number of mammographically indicated biopsies. The goal of this study was to further evaluate the efficacy of SMM in diagnosing or excluding breast carcinoma. This was a prospective case series with each patient serving as her own control. All subjects who had an abnormal mammogram, a palpable breast mass, or both were eligible for inclusion. All patients underwent breast examination, conventional mammography, SMM, and breast biopsy. Of the 81 women originally enrolled, 79 women with 80 lesions completed the study. SMM produced the following results: a sensitivity of 81 per cent, a specificity of 81 per cent, a positive predictive value of 61 per cent, and a negative predictive value of 92 per cent. These values were significantly lower than the pilot study results at a power of 80 per cent and P = 0.05. Our results indicate that SMM does not increase the specificity of conventional mammography and has a low negative predictive value. We would not recommend it as a screening technique to avoid biopsy. 相似文献
50.
U Hettwer FR Jaeckel J Boch M Meyer K Rudolph MS Ullrich 《Canadian Metallurgical Quarterly》1998,64(9):3180-3187
Plant-pathogenic bacteria produce various extracellular polysaccharides (EPSs) which may function as virulence factors in diseases caused by these bacteria. The EPS levan is synthesized by the extracellular enzyme levansucrase in Pseudomonas syringae, Erwinia amylovora, and other bacterial species. The lsc genes encoding levansucrase from P. syringae pv. glycinea PG4180 and P. syringae pv. phaseolicola NCPPB 1321 were cloned, and their nucleotide sequences were determined. Heterologous expression of the lsc gene in Escherichia coli was found in four and two genomic library clones of strains PG4180 and NCPPB 1321, respectively. A 3. 0-kb PstI fragment common to all six clones conferred levan synthesis on E. coli when further subcloned. Nucleotide sequence analysis revealed a 1,248-bp open reading frame (ORF) derived from PG4180 and a 1,296-bp ORF derived from NCPPB 1321, which were both designated lsc. Both ORFs showed high homology to the E. amylovora and Zymomonas mobilis lsc genes at the nucleic acid and deduced amino acid sequence levels. Levansucrase was not secreted into the supernatant but was located in the periplasmic fraction of E. coli harboring the lsc gene. Expression of lsc was found to be dependent on the vector-based Plac promoter, indicating that the native promoter of lsc was not functional in E. coli. Insertion of an antibiotic resistance cassette in the lsc gene abolished levan synthesis in E. coli. A PCR screening with primers derived from lsc of P. syringae pv. glycinea PG4180 allowed the detection of this gene in a number of related bacteria. 相似文献