Role of glycoprotein IIb/IIIa inhibitors in the treatment of degenerated aortocoronary saphenous vein grafts

Treatment of degenerated vein grafts is a large, growing portion of interventional procedures. Because the operative risk of repeat bypass surgery is substantially increased, percutaneous transluminal coronary angioplasty has been accepted as a less invasive treatment in symptomatic patients with significant stenoses of vein grafts. Stent placement has been established in the randomized SAVED trial as a safe and efficient treatment strategy of degenerated saphenous vein grafts, enhancing acute success, reducing the incidence of subsequent angiographic restenosis, and improving event-free survival. Despite coronary stents and new technological innovations like directional and transluminal extraction atherectomy distal embolization is still a frequent occurrence, with a reported incidence of 10-15% associated with an increased in-hospital mortality. Blockade of the platelet surface glycoprotein IIb/IIIa receptors has been convincingly demonstrated to reduce the ischemic complications of angioplasty in native coronary arteries. In degenerated vein grafts the efficacy of glycoprotein IIb/IIIa inhibitors in reducing distal embolization is uncertain. Major clinical events could not be reduced by glycoprotein IIb/IIIa antagonists administered periprocedurally. But prospective randomized trials are lacking. Protection devices could reduce the incidence of distal embolization during interventions in degenerated saphenous vein grafts. The relative role of these devices compared to pharmacologic interventions will require careful assessment in future clinical trials.     

Bacterial antigen-induced release of white cell- and platelet-derived bioactive substances in vitro

Summary Objectives. Poor prognosis after resection of primary colorectal cancer may be related to the combination of perioperative blood transfusion and subsequent development of infectious complications. Various white cell- and platelet-derived cancer-growth substances may be involved in this process. Therefore, we studied the in vitro release of substances from white cells and platelets stimulated by bacterial antigens and supernatants from stored red-cell components. Methods. Eight units of whole blood (WB) and 8 U of buffy-coat-depleted red-cell (SAGM) blood were donated by healthy blood donors. Subsequently, one-half of each unit was leucocyte-depleted by filtration, and all 32 half-units were stored under standard conditions for 35 d. Just after storage, and on d 7, 21, and 35 during storage, aliquots of the supernatants were removed from the units and frozen at −80°C. WB from other healthy donors was stimulated for 2 h with sodium chloride (controls), with Escherichia coli (E. coli) lipopolysaccharide (LPS) alone, or with LPS plus supernatants from the WB units (diluted 1:10), or from the SAGM units (diluted 1:20) stored for 0, 7, 21, or 35 d, respectively. Similar assays were performed using Staphylococcus aureus-derived protein A as a stimulatory antigen. The concentration of eosinophil cationic protein (ECP), myeloperoxidase (MPO), histamine (HIS), and plasminogen-activator inhibitor-1 (PAI-1) were determined in supernatants from the stored blood and in assay supernatants by using enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA) methods. Results. The extracellular concentration of ECP, MPO, and HIS increased significantly in a storage-time-dependent manner in nonfiltered WB and SAGM blood, and the increase was abrogated by prestorage leukofiltration. Similarly, PAI-1 increased significantly in nonfiltered WB, and the increase was abrogated by prestorage leukofiltration. The supernatant concentrations of the four substances were significantly increased in LPS-stimulated (0.5-4 fold) and in protein A-stimulated (0.5-13.5-fold) assays compared with controls. The addition of supernatants from stored nonfiltered WB or SAGM blood significantly increased the assay supernatant of ECP, MPO, HIS, and PAI-1 concentrations storage--time-dependently in LPS-stimulated assays. Prestorage leukofiltration abrogated the additional effect of supernatants from stored blood. Similar results were observed for ECP and HIS through the addition of supernatants from stored blood to protein A-stimulated assays. Protein A stimulation did not lead to increased PAI-1 release in assays diluted by supernatants from stored blood. However, the MPO concentrations were significantly (p=0.004), and independent of storage time and leukofiltration, increased in protein A-stimulated assays diluted by supernatants from stored blood compared with sodium chloride dilution. Conclusion. Extracellular ECP, MPO, HIS, and PAI-1 accumulate during storage of nonfiltered red-cell components, but the accumulation can be prevented by prestorage leukofiltration. In addition, bacterial antigens appear to induce significant release of the substances from white cells and platelets. Addition of supernatants from stored, nonfiltered WB and SAGM blood may increase the substance levels in a storage-time-dependent manner, and prestorage leukofiltration may prevent further increase by supernatants, except for MPO.     

Stimulation of collagenase 3 expression in synovial fibroblasts of patients with rheumatoid arthritis by contact with a three-dimensional collagen matrix or with normal cartilage when coimplanted in NOD/SCID mice

OBJECTIVE: To study the expression of collagenase 3 (matrix metalloproteinase 13 [MMP-13]) and collagenase 1 (MMP-1) in synovial fibroblasts from patients with rheumatoid arthritis (RA) when cultured within 3-dimensional collagen gels or coimplanted with normal cartilage in immunodeficient NOD/SCID mice. METHODS: Messenger RNA (mRNA) and protein expression of collagenase 3 and collagenase 1 were characterized in synovial and skin fibroblasts by Northern blot and Western blot analysis. The mRNA expression of both collagenases in cell-cartilage implants in NOD/SCID mice was investigated by in situ hybridization in combination with immunohistochemistry of human fibroblasts. RESULTS: Synovial fibroblasts coimplanted with normal cartilage in NOD/SCID mice deeply invaded adjacent cartilage tissue. In this in vivo system of cartilage destruction, collagenase 3 mRNA was induced in synovial fibroblasts at sites of cartilage erosion, while the expression of collagenase 1 mRNA could not be detected. Culture of synovial fibroblasts within 3-dimensional collagen gels was associated with a marked increase in collagenase 3 mRNA expression and proenzyme production. This stimulatory effect was 1 order of magnitude higher in comparison with a 2-4-fold increase upon treatment with interleukin-1beta or tumor necrosis factor a. In contrast, mRNA expression and proenzyme production of collagenase 1 were increased strongly, and to a similar extent, either by contact with 3-dimensional collagen or by proinflammatory cytokines. CONCLUSION: The expression of collagenase 3, in contrast to that of collagenase 1, is preferentially stimulated in synovial fibroblasts by 3-dimensional collagen rather than by proinflammatory cytokines. The induction of collagenase 3 by cell-matrix interactions represents a potential mechanism contributing to the invasive phenotype of synovial fibroblasts at sites of synovial invasion into cartilage in RA.     

Replicative aging of human articular chondrocytes during ex vivo expansion

OBJECTIVE: To investigate the contribution of clinical ex vivo expansion protocols to replicative aging of human chondrocytes. METHODS: Primary human chondrocytes were cultured as monolayers after isolation from 7 articular cartilage specimens. Cells were passaged corresponding to 12-19 cell population doublings (cpd). Aliquots of the cells were collected from each passage and analyzed for telomere length and telomerase activity. RESULTS: The rate of telomere shortening was heterogeneous, ranging from 147 to 431 bp/cpd (mean +/- SD 305 +/- 122). Telomerase activity was detected at various time points during passaging in 5 of 7 primary chondrocytes analyzed, but not in native human articular cartilage specimens. According to our data, an 8-10-fold ( approximately 3 cpd) ex vivo expansion of articular chondrocytes, as typically performed for transplantation procedures, leads to telomere erosion in the range of 900 bp. This is comparable with 30 years of aging based on the in vivo rate of telomere shortening of 30 bp/year recently found in chondrocytes. CONCLUSION: If telomere shortening is an important determinant of aging in human articular cartilage, an additional telomere loss due to ex vivo expansion might affect the incidence or time of onset of age-related cartilage disorders. However, given the limited extent of expansion performed in the clinical setting to date, a significant telomere-mediated increase in the risk of malignant transformation or replicative exhaustion of the transplanted cells seems unlikely.     

Efficient Co-Replication of Defective Novirhabdovirus

We have generated defective Viral Hemorrhagic Septicemia Viruses (VHSV) which express either the green fluorescent protein (GFP) or a far-red fluorescent protein (mKate) by replacing the genes encoding the nucleoprotein N or the polymerase-associated P protein. To recover viable defective viruses, rVHSV-ΔN-Red and rVHSV-ΔP-Green, fish cells were co-transfected with both deleted cDNA VHSV genomes, together with plasmids expressing N, P and L of the RNA-dependent RNA polymerase. After one passage of the transfected cell supernatant, red and green cell foci were observed. Viral titer reached 10⁷ PFU/mL after three passages. Infected cells were always red and green with the very rare event of single red or green cell foci appearing. To clarify our understanding of how such defective viruses could be so efficiently propagated, we investigated whether (i) a recombination event between both defective genomes had occurred, (ii) whether both genomes were co-encapsidated in a single viral particle, and (iii) whether both defective viruses were always replicated together through a complementation phenomenon or even as conglomerate. To address these hypotheses, genome and viral particles have been fully characterized and, thus, allowing us to conclude that rVHSV-ΔN-Red and rVHSV-ΔP-Green are independent viral particles which could propagate only by simultaneously infecting the same cells.     

Influence of intestinal inflammation (IBD) and small and large bowel length on fecal short-chain fatty acids and lactate

Treatment with short-chain fatty acids (SCFAs) seems promising in ulcerative colitis and changes in colonocyte oxidation of butyrate have been suggested to be of importance for the development of this disease. The influence of small and large bowel length after surgery on SCFAs is only partly known. SCFAs and lactate were measured in consecutive fecal samples from 300 patients with ulcerative colitis (103), Crohn's disease (127), and noninflammatory bowel disease (70); 205 had had surgery, 52 had short bowels (<200 cm). Lactate (mainly thel-isomer) was elevated in ulcerative colitis patients with pancolitis (mean ±sem, 17±5 mmol/liter) and proctitis (12±3 mmol/liter) compared with quiescent ulcerative colitis (3±1 mmol/liter,P<0.01), and correlated with the index of Truelove (R=0.52,P<0.0005). Lactate was also increased in Crohn's colitis (21±8 mmol/liter), but not in isolated ileitis (4±2 mmol/liter), compared with quiescent Crohn's disease (7±2 mmol/liter,P<0.02), but did not correlate with the activity index (CDAI;R=0.18,P=0.12). In contrast to earlier reports, SCFAs (including butyrate) did not correlate with inflammatory activity or localization in either ulcerative colitis or Crohn's disease. The length of the small bowel had no influence on SCFAs and lactate in patients with either no colonic function (ileostomies), or with >50% and <50% preserved colorectal length, respectively. Fecal SCFAs from completely (100%) preserved large bowels (89±5 mmol/liter), and from>50% (76±7 mmol/liter) and<50% (72±7 mmol/liter) preserved colons were not significantly different, in contrast to SCFAs from ileorectals (51±10 mmol/liter), ileal reservoirs (57±6 mmol/liter), and ileostomies (20±2 mmol/liter). Fecal lactate is associated with proctocolitis, but not with ileitis. SCFAs were remarkably constant and not influenced by active inflammation in patients with inflammatory bowel disease or extreme differences in the length of the small or large intestine.     

Specific vaccine therapy in chronic hepatitis B: induction of T cell proliferative responses specific for envelope antigens.

In a pilot study, it was established that specific therapy by standard anti-hepatitis B virus (HBV) vaccination may be effective in reducing HBV replication and canceling the immune tolerance to hepatitis B surface antigen (HBsAg) particles in about 50% of persons with chronic active HBV replication. In the present study, the vaccine-induced immune responses were analyzed during an ongoing controlled multicenter vaccine trial. Vaccination elicited peripheral blood mononuclear cell proliferative responses specific for envelope antigen in 7 of 27 subjects given HBsAg. The responses induced by the vaccines were mediated by CD4+ T lymphocytes, and at least three different epitopes were recognized. HBV-specific CD4+ T lymphocytes produced high levels of interferon-gamma [corrected] and belonged to a T helper 1 subset. Reduction of serum HBV DNA in some of these persons suggests that induction of CD4+ T cell responses could be important in controlling viremia during vaccine therapy of chronic HBV carriers.