The effect of clopidogrel treatment on osseointegration of titanium implants. A histomorphometric study in rabbits.

PURPOSE: Clopidogrel is a P2Y12 purinergic receptor inhibitor and a widely prescribed antiplatelet drug for the prevention of atherosclerotic events. Accumulated evidence suggests that purinergic receptors regulate important functions in bone healing and homeostasis. The purpose of the present study was to evaluate the effect of continuous perioperative clopidogrel treatment on osseointegration of titanium implants. MATERIALS AND METHODS: Thirty two white New Zealand rabbits were randomly assigned in two groups: a clopidogrel group and a control group. Rabbits of the clopidogrel group received daily 3mg/kg of clopidogrel and the control group received vehicle for one week prior to the surgical placement of a titanium implant in their medial femoral condyle; treatment was continued for another six weeks postoperative. At this time, postmortem histologic and histomorphometric evaluation of the implants was performed. RESULTS: Surgical procedures and postoperative period were uneventful and well tolerated by all animals without any surgical wound dehiscence, signs of infection or other complication. No implant failure was observed in any of the groups. Histomorphometric analysis showed that BIC (%) was 48.77% for the clopidogrel group and 34.65% for the control group with statistically significant difference between them (P < 0.001). Moreover, clopidogrel group had significantly greater bone tissue density (40.52 % vs 28.74 %, p<0.001) and mean trabecular thickness (284.7 µm vs 180.7 µm, p<0.001) in proximity to the implant surface, while mean trabecular number had no difference between groups (1.56 vs 1.60, p=0.961). CONCLUSIONS: The present study showed that continuous clopidogrel treatment does not negatively affect osseointegration, but rather promotes it in terms of BIC and bone density around the titanium implants. Further studies on the effect of the P2Y12 receptor and its antagonists on peri-implant bone homeostasis may provide useful information or applications for long-term success of dental implant therapy.

Wide Awake Open Carpal Tunnel Release: The Effect of Local Anesthetics in the Postoperative Outcome.

Introduction Wide awake open carpal tunnel decompression is a procedure performed under local anesthesia. This study aimed to present the effect of various local anesthetics in peri and postoperative analgesia in patients undergoing this procedure. Materials and Methods A total of 140 patients, with 150 hands involved, underwent carpal tunnel release under local anesthesia. Patients were divided in five groups according to local anesthetic administered: lidocaine 2%, ropivacaine 0.75%, ropivacaine 0.375%, chirocaine 0.5%, and chirocaine 0.25%. Total 400 mg of gabapentin were administered to a subgroup of 10 cases from each group (50 cases totally), 12 hours before surgery. Patients were evaluated immediately, 2 weeks and 2 months after surgery according to VAS pain score, grip strength, and two-point discrimination. Results In all patients, pain and paresthesia improved significantly postoperatively, while the use of gabapentin did not affect outcomes. Grip strength recovered and exceeded the preoperative value 2 months after surgery, without any difference between the groups. No case of infection, hematoma, or revision surgery was reported. Conclusion Recovery after open carpal tunnel release appears to be irrelevant of the type of local anesthetic used during the procedure. Solutions of low local anesthetic concentration (lidocaine 2%, ropivacaine 0.375%, and chirocaine 0.25%) provide adequate intraoperative analgesia without affecting the postoperative course.

Effect of clopidogrel in bone healing-experimental study in rabbits.

BACKGROUND: Clopidogrel is a widely prescribed drug for prevention of myocardial infarction and stroke in patients at risk. It inhibits thrombus formation via inhibition of the P2Y12 purinergic receptor on platelets, which is important in their activation by ADP. However, the P2Y12 receptor has also been found to be expressed in both osteoblasts and osteoclasts. Accumulated evidence suggests that purinergic receptors regulate important functions of bone turnover. Previous studies on the effect of clopidogrel on bone metabolism indicated potential harmful effects, but their results remain conflicting. Thus, clopidogrel treatment may affect bone healing, but it has not yet been studied. AIM: To evaluate if continuous perioperative clopidogrel treatment has any negative effect on bone healing in the rabbit calvarial defect model. METHODS: Sixteen male white New Zealand rabbits were randomly assigned in two groups: One group received daily 3 mg/kg of clopidogrel per os and the other group received the vehicle alone for a week prior to the surgical procedures; the treatments were continued for another 6 wk postoperatively. The surgical procedures included generation of two circular calvarial defects 11 mm in diameter in every animal. After the 6-wk period of healing, postmortem radiographic and histomorphometric evaluation of the defects was performed. RESULTS: Both the surgical procedures and the postoperative period were uneventful and well tolerated by all the animals, without any surgical wound dehiscence, signs of infection or other complication. New bone was formed either inwards from the defect margins or in the central portion of the defect as separated bony islets. While defect healing was still incomplete in both groups, the clopidogrel group had significantly improved radiographic healing scores. Moreover, the histomorphometric analysis showed that bone regeneration (%) was 28.07 ± 7.7 for the clopidogrel group and 19.47 ± 4.9 for the control group, showing a statistically significant difference between them (P = 0.018). Statistically significant difference was also found in the defect bridging (%), i.e. 72.17 ± 21.2 for the clopidogrel group and 41.17 ± 8.5 for the control group, respectively (P = 0.004), whereas there was no statistical difference in bone tissue density between the groups. CONCLUSION: Our results indicate that maintenance of perioperative clopidogrel treatment does not negatively affect bone healing but rather promotes it. Further research is needed in order to find useful applications of this finding.

Silencing of caveolin-1 in fibroblasts as opposed to epithelial tumor cells results in increased tumor growth rate and chemoresistance in a human pancreatic cancer model.

Caveolin­1 (Cav­1) expression has been shown to be associated with tumor growth and resistance to chemotherapy in pancreatic cancer. The primary aim of this study was to explore the significance of Cav­1 expression in pancreatic cancer cells as compared to fibroblasts in relation to cancer cell proliferation and chemoresistance, both in vitro and in vivo, in an immunodeficient mouse model. We also aimed to evaluate the immunohistochemical expression of Cav­1 in the epithelial and stromal component of pancreatic cancer tissue specimens. The immunohistochemical staining of poorly differentiated tissue sections revealed a strong and weak Cav­1 expression in the epithelial tumor cells and stromal fibroblasts, respectively. Conversely, the well­differentiated areas were characterized by a weak epithelial Cav­1 expression. Cav­1 downregulation in cancer cells resulted in an increased proliferation in vitro; however, it had no effect on chemoresistance and growth gain in vivo. By contrast, the decreased expression of Cav­1 in fibroblasts resulted in a growth advantage and the chemoresistance of cancer cells when they were co­injected into immunodeficient mice to develop mixed fibroblast/cancer cell xenografts. On the whole, the findings of this study suggest that the downregulation of Cav­1 in fibroblasts is associated with an increased tumor proliferation rate in vivo and chemoresistance. Further studies are warranted to explore whether the targeting of Cav­1 in the stroma may represent a novel therapeutic approach in pancreatic cancer.

Synthesis and biological evaluation of modified purine homo-N-nucleosides containing pyrazole or 2-pyrazoline moiety.

9-Substituted (pyrazol-5-yl)methyl- or (2-pyrazolin-5-yl)methyl-9H-purines were synthesized from 9-allyl-6-chloro-9H-purine through the 1,3-dipolar cycloaddition reaction with nitrile imines, prepared in situ from the corresponding hydrazone and NBS/Et3N under MW or from hydrazinoylchloride and Et3N under reflux. The coupling of new 6-chloropurines with amines in H2O under microwaves resulted quantitatively to modified pyrazol-5-yl- or 2-pyrazolin-5-yl adenine homo-N-nucleosides. The new compounds were tested in vitro for their ability to: (i) interact with 1,1-diphenyl-2-picryl-hydrazyl (DPPH), (ii) inhibit lipid peroxidation, (iii) inhibit the activity of soybean lipoxygenase, (iv) inhibit in vitro thrombin and for (v) their antiproliferative and cytotoxic activity. Pyrazolines were found to be more potent in vitro. Compound 7a exhibited satisfactory combined antioxidant and anti-lipid peroxidation activity, inhibition of lipoxygenase (89%) and thrombin inhibitory ability, whereas compound 7b exhibited high lipoxygenase inhibitory activity in combination to significant anti-thrombin activity. No compound exhibited a significant cytotoxic activity, while all showed moderate antiproliferative activity.

Activity of Tigecycline in combination with Colistin, Meropenem, Rifampin, or Gentamicin against KPC-producing Enterobacteriaceae in a murine thigh infection model.

Limited antimicrobials remain active for treating severe infections due to KPC-producing pathogens, and optimal regimens have not been established. In murine thigh infections caused by nine KPC-producing clinical strains of Enterobacteriaceae (meropenem MICs, 1 to 4 µg/ml), we evaluated the activities of tigecycline, colistin, meropenem, rifampin, and gentamicin in single and combination regimens lasting for 24 h and 48 h. Rifampin, tigecycline, and gentamicin were the most effective monotherapies, reducing significantly the CFU counts yielded from thighs infected by 88.9 to 100%, 77.8 to 88.9%, and 66.7 to 88.9% of strains, respectively; meropenem and colistin alone exhibited considerably lower performance (significant CFU reduction in 33.3% and 22.2 to 33.3% of the strains, respectively). The addition of rifampin or gentamicin to tigecycline produced synergistic effect in most strains, while antagonism was observed in 33.3 to 44.4% of the strains when colistin was added to tigecycline and in 44.4 to 55.5% of the strains for meropenem combination with tigecycline. Tigecycline combinations with gentamicin or with rifampin caused higher CFU reductions than did tigecycline plus colistin or plus meropenem with almost all strains. Furthermore, tigecycline plus gentamicin was significantly more effective than tigecycline plus colistin or tigecycline plus meropenem in 33.3 to 44.4% and 55.5 to 66.7% of the strains, respectively, while tigecycline plus rifampin significantly outperformed tigecycline plus colistin and tigecycline plus meropenem in 33.3% and 66.7 to 77.8% of the strains, respectively. Overall, our in vivo study showed that tigecycline plus rifampin or plus gentamicin is a robust regimen against soft tissue infections caused by KPC-producing strains. The combinations of tigecycline with colistin or meropenem should be considered with caution in clinical practice.

Comparison of mannitol and hypertonic saline in the treatment of severe brain injuries.

OBJECT: The purpose of this study was to compare the effects of mannitol and hypertonic saline in doses of similar osmotic burden for the treatment of intracranial hypertension in patients with severe traumatic brain injury. METHODS: The authors used an alternating treatment protocol to compare the effect of hypertonic saline with that of mannitol given for episodes of increased intracranial pressure in patients treated for severe head injury at their hospital during 2006-2008. Standard guidelines for the management of severe traumatic brain injury were followed. Elevated intracranial pressure (ICP) was treated either with mannitol or hypertonic saline. Doses of similar osmotic burden (mannitol 20%, 2 ml/kg, infused over 20 minutes, or saline 15%, 0.42 ml/kg, administered as a bolus via a central venous catheter) were given alternately to the individual patient with severe brain injury during episodes of increased pressure. The dependent variables were the extent and duration of reduction of increased ICP. The choice of agent for treatment of the initial hypertensive event was determined on a randomized basis; treatment was alternated for every subsequent event in each individual patient. Reduction of ICP and duration of action were recorded after each event. Results obtained after mannitol administration were statistically compared with those obtained after hypertonic saline administration. RESULTS: Data pertaining to 199 hypertensive events in 29 patients were collected. The mean decrease in ICP obtained with mannitol was 7.96 mm Hg and that obtained with hypertonic saline was 8.43 mm Hg (p = 0.586, equal variances assumed). The mean duration of effect was 3 hours 33 minutes for mannitol and 4 hours 17 minutes for hypertonic saline (p = 0.40, equal variances assumed). CONCLUSIONS: No difference between the 2 medications could be found with respect to the extent of reduction of ICP or duration of action.

Neuroleptospirosis with hydrocephalus and very elevated cerebrospinal fluid protein.

To our knowledge, this is the first known case of a patient with leptospirosis and very elevated CSF, which caused hydrocephalus.

Variants of the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene and risk of stroke: a HuGE gene-disease association review and meta-analysis.

Variants of the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene have been implicated as a risk factor for stroke. However, genetic association studies that have examined the association between ALOX5AP gene variants (HapA haplotype, HapB haplotype, and SG polymorphisms) and stroke have produced conflicting results. Therefore, the authors performed a meta-analysis of all studies with ALOX5AP genotyping (5,194 stroke cases and 4,566 controls). The meta-analysis showed significant heterogeneity among studies (P(Q) = 0.03, I(2) = 63%) and a nonsignificant association between the HapA haplotype (SG13S25G-SG13S114T-SG13S89G-SG13S32A) and stroke risk (random-effects (RE) odds ratio (OR) = 1.13, 95% confidence interval (CI): 0.88, 1.45). Regarding the HapB haplotype (SG13S377A-SG13S114A-SG13S41A-SG13S35G), there was no association with stroke risk (RE OR = 1.03, 95% CI: 0.77, 1.37). The SG13S114, SG13S89, SG13S25, SG13S32, SG13S35, and SG13S42 polymorphisms were not associated with stroke. The SG13S106 and SG13S377 polymorphisms revealed evidence of marginal association (RE OR = 1.23 (95% CI: 1.03, 1.46) and RE OR = 1.25 (95% CI: 1.04, 1.50), respectively). However, cumulative meta-analysis for the HapA haplotype showed a downward trend of odds ratios over time, and recursive cumulative meta-analysis indicated insufficient evidence for claiming or denying an association. Tests for bias revealed no evidence of biases. Rigorous genetic association studies investigating gene-gene-environment interactions may generate more conclusive claims about the genetics of stroke.

Influence of diabetes mellitus on cervical intervertebral disc herniation.

OBJECTIVES: To establish if patients treated surgically for cervical disc disease have an increased incidence of diabetes mellitus. PATIENTS AND METHODS: We prospectively studied 66 consecutive patients who were treated surgically for cervical disc disease and compared them with 100 age-matched patients at the same time period who underwent surgery for other reasons. RESULTS: There was a significantly increased incidence of diabetes mellitus in the first group. This increased incidence was even higher than that in historical controls treated surgically for lumbar disc disease. Short-term postoperative prognosis was good in our patients. We describe the relationship between diabetes mellitus and cervical disc disease. CONCLUSION: There is an increased incidence of diabetes among patients undergoing surgery for cervical disc disease.

The selective 5-HT(6) receptor antagonist Ro 04-6790 attenuates psychotomimetic effects of the NMDA receptor antagonist MK-801.

There are experimental evidences indicating that the non-competitive NMDA receptor antagonist MK-801 impairs cognition and produces a series of schizophrenia-like symptoms in rodents (hypermotility, stereotypies and ataxia). The present study was designed to investigate the efficacy of the selective 5-HT(6) receptor antagonist Ro 04-6790 in counteracting these MK-801-induced behavioural effects in the rat. The effects of Ro 04-6790 in antagonizing MK-801-induced memory deficits were assessed using the object recognition task. The ability of this 5-HT(6) receptor antagonist in counteracting hypermotility, stereotypies and ataxia produced by MK-801 were evaluated in a motor activity cage. Post-training administration of Ro 04-6790 (10 and to some extent also 3mg/kg) antagonized MK-801-induced performance deficits in a recognition memory test. In a subsequent study, Ro 04-6790 (3 and 10 mg/kg) reversed hypermotility and ataxia produced by MK-801. This 5-HT(6) receptor antagonist also alleviated MK-801-induced certain stereotypies. Our findings indicate that Ro 04-6790 attenuates behavioural effects related to the hypofunction of the NMDA receptor suggesting that this compound might be involved in the psychotomimetic effects of non-competitive NMDA receptor antagonists.

Is 472G/A catechol-O-methyl-transferase gene polymorphism related to panic disorder?

OBJECTIVES: Case-control studies relating 472G/A catechol-O-methyl-transferase polymorphism with the risk of developing panic disorder showed inconclusive or contradictory results. To shed some light on these results a meta-analysis of all available case-control studies was conducted. METHODS: We searched PubMed database for English-languages case-control studies using the key words: Catechol-O-methyl-transferase and panic. Case-control studies that determined the distribution of 472G/A genotypes in cases with primary and predominant panic disorder, and in controls free of psychiatric disorders were eligible for inclusion in the meta-analysis. The pooled risk effect (odds ratio, OR) was estimated using fixed effects and random effects (RE) models. The heterogeneity between studies was tested using the Q-statistic, heterogeneity was also quantified with the I metric. Possible sources of bias were also explored. RESULTS: The main analysis for investigating the association of the allele G and the risk of developing panic disorder relative to the allele A, showed significant heterogeneity (PQ<0.01, I=79%) between studies, then the RE OR was nonsignificant, heterogeneity OR=1.04 with 95% confidence interval (0.71-1.53). Although for both sexes the OR was not significant, there is evidence that in females the risk of PD [RE OR=1.07 (0.54-2.11)] was greater than in males [RE OR=0.86 (0.53-1.39)]. Inconsistency in genetic effects between East Asians [RE OR=0.73 (0.41-1.30) and (PQ=0.03, I=73%)] and Caucasians [OR=1.26 (0.93-1.69) and (PQ=0.24, I=28%)] existed. The genotype differences for the homozygotes, the recessive and dominant models for allele G produced the same overall pattern like the allele contrast in terms of association and heterogeneity. No differential magnitude of effect in large versus small studies for each polymorphism investigating was found. The cumulative meta-analysis showed an increase in OR as evidence accumulated. CONCLUSIONS: No conclusive evidence showing that 472G/A polymorphism is a reliable marker for panic disorder was found; moreover, large heterogeneity between studies existed. Large and more rigorous association studies investigating also the interaction with other genetic/environmental factors might provide more conclusive evidence.

Memantine and recognition memory: possible facilitation of its behavioral effects by the nitric oxide (NO) donor molsidomine.

The effects of the non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist memantine on recognition memory were investigated in the rat by using the object recognition task. In addition, a possible interaction between memantine and the nitric oxide (NO) donor molsidomine in antagonizing extinction of recognition memory was also evaluated utilizing the same behavioral procedure. In a first dose-response study, post-training administration of memantine (10 and 20, but not 3 mg/kg) antagonized recognition memory deficits in the rat, suggesting that memantine modulates storage and/or retrieval of information. In a subsequent study, combination of sub-threshold doses of memantine (3 mg/kg) and the NO donor molsidomine (1 mg/kg) counteracted delay-dependent impairments in the same task. Neither memantine (3 mg/kg) nor molsidomine (1 mg/kg) alone reduced object recognition performance deficits. The present findings indicate a) that memantine is involved in recognition memory and b) support a functional interaction between memantine and molsidomine on recognition memory mechanisms.