Do patients with basilar or vertebral artery stenosis have a higher stroke incidence poststenting?

BACKGROUND AND AIM

Posterior circulation stenosis may be a risk factor associated with stroke after intracranial stenting as compared with anterior circulation stenosis. Our aim was to test our hypothesis that there was no difference in clinical outcome poststenting between patients with severe stenosis of the basilar artery (BA) and intracranial vertebral artery (VA).

METHODS

Using the Cox proportional hazards regression model adjusted for prespecified factors (qualifying event, and timing of stenting after the qualifying event), we compared primary endpoint (ischemic stroke in the vertebrobasilar territory, including any stroke or death within 30 days of stenting) between patients with severe symptomatic atherosclerotic BA and VA stenosis who underwent elective stenting in our prospective database. Analysis was by intention-to-treat principle.

RESULTS

Primary endpoint event occurred in 13 (18.8%) of 69 patients with BA stenosis during a mean 23.4 months (9 within 30 days and 4 afterward) and 3 (4.3%) of 70 patients with VA stenosis during a mean 26.4 months (2 within 30 days and 1 afterward). Patients with BA stenosis had a significantly higher risk of the primary endpoint (adjusted HR=4.87, 95% CI 1.37 to 17.29; p=0.014) or any stroke or death within 30 days of stenting (adjusted HR=5.13, 95% CI 1.10 to 23.96; p=0.038) than those with VA stenosis.

CONCLUSION

A significantly higher stroke risk poststenting exists in patients with severe BA stenosis than those with VA stenosis. The discrepancy in clinical outcome after stenting between patients with BA and VA stenosis should be considered in clinical practice and stenting trials.

Effect of supplemental Bacillus cultures on rumen fermentation and milk yield in Chinese Holstein cows

Two experiments were conducted to study the effect of supplemental 100 g/day of live Bacillus cultures (2 x 10(11) cell of Bacillus subtilis and Bacillus licheniformis) on rumen fermentation as well as milk yield and composition in Chinese Holstein cows. In experiment 1, investigating 3 x 10 cows, milk yield and milk protein were increased by using B. licheniformis (p < 0.05) in comparison with an unsupplemented group and the B. subtilis group. Body weight was not significantly affected by Bacillus culture supplementation (p > 0.05). Percentage of milk fat and lactose was not significantly different between treatments (p > 0.05). But milk protein increased with B. licheniformis supplementation (p < 0.05). In experiment 2, carried out with three non-lactating ruminally and duodenally fistulated cows, results showed that B. licheniformis supplementation increased microbial crude protein flow into duodenum (p < 0.05) and decreased the ammonia nitrogen concentration in ruminal fluid at 0.5 h, 1 h, 3 h, 6 h after morning feeding (p < 0.05). Bacillus licheniformis supplementation increased total VFA and acetate concentration in ruminal fluid at 0.5 h, 1 h, 3 h, 6 h after morning feeding (p < 0.05). Bacillus subtilis had no significant effect on rumen fermentation characteristics, duodenal microbial N flow and ruminal apparent nutrient digestibility (p > 0.05). Bacillus licheniformis increased ruminal apparent nutrient digestibility of neutral detergent fibre, acid detergent fibre, and organic matter (p < 0.05).

Chronic ketamine impairs fear conditioning and produces long-lasting reductions in auditory evoked potentials

Ketamine is an NMDA receptor antagonist with a variety of uses, ranging from recreational drug to pediatric anesthetic and chronic pain reliever. Despite its value in the clinical setting, little is known about the immediate and long-lasting effects of repeated ketamine treatment. We assessed the effects of chronic administration of a subanesthetic dose of ketamine on contextual fear conditioning, detection of pitch deviants and auditory gating. After four, but not two, weeks of daily ketamine injections, mice exhibited decreased freezing in the fear conditioning paradigm. Gating of the P80 component of auditory evoked potentials was also significantly altered by treatment condition, as ketamine caused a significant decrease in S1 amplitude. Additionally, P20 latency was significantly increased as a result of ketamine treatment. Though no interactions were found involving test week, stimulus and treatment condition, these results suggest that repeated ketamine administration impairs fear memory and has lasting effects on encoding of sensory stimuli.

Cell sources for cardiovascular tissue regeneration and engineering

The heart has long been regarded as a post-mitotic organ. Since many years, physicians have focused on developing strategies to restore the myocardium after ischemic damage followed by ventricular dysfunction. Restoration is generally achieved through the redirection of blood flow or by supporting contractile performance. The discovery of stem cells capable of generating angiogenic or contractile cells and structures offers new horizons to patients suffering from myocardial disease. Experimental studies indicate that the delivery or mobilization of stem and progenitor cells may improve tissue perfusion and the contractile performance of the damaged heart. Another aspect of restoration is based on cardiovascular tissue engineering and the creation of three-dimensional biological conformations to replace the artificial materials frequently used during operations, i.e., valves and grafts, or even a portion of the nonfunctional myocardial tissue. At present, the underlying intra- and intercellular molecular mechanisms controlling myocardiogenesis and cardiomyocyte replacement during regenerative processes are not very well understood. In this brief review we try to give the answers to questions on certain aspects of myocardial tissue regeneration and engineering procedures.

Fibre based cellular transfection

Optically assisted transfection is emerging as a powerful and versatile method for the delivery of foreign therapeutic agents to cells at will. In particular the use of ultrashort pulse lasers has proved an important route to transiently permeating the cell membrane through a multiphoton process. Though optical transfection has been gaining wider usage to date, all incarnations of this technique have employed free space light beams. In this paper we demonstrate the first system to use fibre delivery for the optical transfection of cells. We engineer a standard optical fibre to generate an axicon tip with an enhanced intensity of the remote output field that delivers ultrashort (~ 800 fs) pulses without requiring the fibre to be placed in very close proximity to the cell sample. A theoretical model is also developed in order to predict the light propagation from axicon tipped and bare fibres, in both air and water environments. The model proves to be in good agreement with the experimental findings and can be used to establish the optimum fibre parameters for successful cellular transfection. We readily obtain efficiencies of up to 57 % which are comparable with free space transfection. This advance paves the way for optical transfection of tissue samples and endoscopic embodiments of this technique.

Comparison of hepatic oxidative DNA damage in patients with chronic hepatitis B and C

8-Hydroxydeoxyguanosine (8-OHdG) is a promutagenic DNA lesion produced by hydroxyl radicals and is recognized as a useful marker in estimating DNA damage induced by oxidative stress. The aim of this study was to clarify the clinical significance of hepatic 8-OHdG levels in patients with chronic viral hepatitis. Hepatic 8-OHdG accumulation was investigated in patients with chronic hepatitis C (CH-C) (n = 77) and chronic hepatitis B (CH-B) (n = 34) by immunohistochemical staining of liver biopsy samples. 8-OHdG positive hepatocytes were significantly higher in patients with CH-C compared to CH-B (median 55.0 vs 18.8 cells/10(5) mum(2), P < 0.0001). The number of positive hepatocytes significantly increased with the elevation of serum aminotransferase levels, especially in CH-C patients (8-OHdG vs alanine aminotransferase (ALT)/aspartate aminotrasferase (AST) were r = 0.738/0.720 in CH-C and 0.506/0.515 in CH-B). 8-OHdG reactivity was strongly correlated with body and hepatic iron storage markers in CH-C (vs serum ferritin, r = 0.615; vs hepatic total iron score, r = 0.520; vs hepatic hepcidin mRNA levels, r = 0.571), although it was related to serum HBV-DNA titers (r = 0.540) and age of patients (r = -0.559) in CH-B. These results indicate that hepatic oxidative DNA damage is common in chronic viral hepatitis, in particular chronic HCV-infected patients, suggesting a possible link between chronic hepatic inflammation and hepatocarcinogenesis. The strong positive correlation between hepatic DNA damage and iron overload suggests that iron content is one of the most likely mediators of hepatic oxidative stress and iron reduction may be beneficial to reduce the incidence of hepatic cancer in CH-C patients.

Long-term outcome of elective stenting for symptomatic intracranial vertebrobasilar stenosis

Seventy-nine consecutive patients with symptomatic atherosclerotic stenosis > or = 50% of intracranial vertebrobasilar artery (VBA) were treated by elective stenting. There were five strokes within 30 days, and three strokes in the VBA territory after 30 days (mean of 812 days). The annual stroke rate in the VBA territory (including any stroke and death within 30 days) was 4.6%. At the last follow-up time, 73 patients were independent (modified Rankin scale grade < or = 2). The outcome compares favorably with medical therapy.

Comparison of elective stenting of severe vs moderate intracranial atherosclerotic stenosis

OBJECTIVE

To test whether symptomatic severe intracranial atherosclerotic stenosis was associated with a higher subsequent stroke risk than moderate stenosis after elective angioplasty with a balloon-expandable stent and to explore which factors were associated with the subsequent stroke.

METHODS

Between September 2001 and June 2005, there were 220 symptomatic intracranial atherosclerotic stenoses in 213 patients undergoing elective stenting at our institute. Of these stenoses, 126 in 121 patients were > or =70% severe stenoses, and 94 in 92 patients were 50% to 69% moderate stenoses. Primary endpoints included lesion-related ischemic stroke, and symptomatic brain or subarachnoid hemorrhage.

RESULTS

Ten primary endpoint events occurred in the severe stenosis group (six within 30 days and four in mean follow-up of 26.0 months after 30 days), and seven occurred in the moderate stenosis group (four within 30 days and three in mean follow-up of 27.6 months after 30 days). There was no significant difference in cumulative probability of primary endpoints between the severe (7.2% at 1 year and 8.2% at 2 years) and moderate (5.3% at 1 year and 8.3% at 2 years) stenosis groups. No single factor was found to be associated with primary endpoints in the moderate stenosis group. Multivariable analysis revealed that stent failure was the only predictor of primary endpoints in the severe stenosis group (hazard ratio 5.31, 95% CI 1.35 to 20.91).

CONCLUSION

Symptomatic severe intracranial atherosclerotic stenosis did not present a higher subsequent stroke risk than moderate stenosis after elective angioplasty with a balloon-expandable stent. Patients with severe stenosis may benefit from successful stent placement, and randomized trials are necessary to demonstrate this possible benefit.

Umbilical cord blood cell transplantation for myocardial regeneration

Bone marrow remains the most frequently used source of adult stem cells, but its angiogenic and possibly also myogenic potentials are likely to regress with increasing donor age and morbidity. Recently, cord blood has been suggested as a readily available source for non-embryonic stem cells with high regenerative capacity. We first tested the capacity of mononuclear cells obtained from human umbilical cord blood (UCB(mn)) to migrate to the heart on IV delivery in NOD/Scid mice. As evidenced by the presence of human DNA by PCR analysis, UCB(mn) cells migrated to the heart in 50% of the mice with myocardial infarctions, but in none of the sham-operated control mice. In UCB(mn) cell-positive injured hearts, the infarct size was smaller and capillary density higher in the ischemic myocardium. By immunohistology, we observed endothelial cell differentiation of UCB(mn) cells in the heart but there was no colocalization of UCB cell-specific antibodies with markers of myocyte-type cells. In a second series of experiments, we injected 5 x 10(5) UCB cells enriched for CD133 directly into the necrotic myocardium of NOD/Scid mice. Comparisons were performed with an equivalent number of CD133+ bone marrow (BM) cells or a sham injection in the respective control groups. Both BMCD133+ and UCBCD133+ cells abolished postoperative mortality and improved capillary density in the injured myocardium, but only BMCD133+ cells led to a detectable improvement in myocardial contractility in vivo. We conclude that human UCB cells facilitated neovascularization of ischemic myocardium, but their capacity for formation of contractile neotissue needs further investigation.