Affordable Method for Hematocrit Determination in Murine Models

Hematocrit (Hct) is a powerful tool often used in a clinical setting for the diagnosis of blood conditions such as anemia. It is also used in the research field as a hematological parameter in both human and mouse models. Measuring Hct, however, involves the use of expensive standardized equipment (such as a CritSpin™ Microhematocrit Centrifuge). Here, we describe a novel, simple, and affordable method to determine the Hct in untreated wild-type (WT) mice and phenylhydrazine (PHZ)-induced anemic mice with reasonable accuracy, using a benchtop centrifuge commonly available in laboratories. Hct of murine samples processed with a benchtop centrifuge, when compared to the standardized method CritSpin™, showed comparable results. This approach for determining Hct of murine can prove useful to research laboratories that cannot afford specialized equipment for Hct studies. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Affordable Method for Hematocrit Determination in Murine Models Basic Protocol 2: Murine Sample Validation Support Protocol: Phenylhydrazine-induced anemia in wild-type (WT) mice.

Cytotoxic Effects of the Schweinfurthin Analog 5′-Methylschweinfurthin G in Malignant Plasma Cells

<b><i>Introduction:</i></b> Multiple myeloma (MM) is a B plasma cell malignancy currently incurable, and novel therapeutics are needed. Evidences regarding the effect of natural compound schweinfurthins suggest that hematological cancers showed growth inhibitory effects to this family of compounds at single nanomolar concentrations. In this study, we evaluated the cytotoxicity of the schweinfurthin synthetic analog 5′-methylschweinfurthin G (MeSG) in MM cell lines, to better understand the validity of this compound as a therapeutic candidate for further studies in MM. <b><i>Methods:</i></b> MeSG toxicity against MM cell lines RPMI-8226, MM.1S, and H-929 was evaluated. Trypan blue exclusion and MTT assays measured cell viability and mitochondrial activity, respectively. Flow cytometry was performed to detect apoptotic mitochondria. Flow cytometry and Western blotting techniques were used to investigate apoptosis and to examine the cell cycle. Western blotting was used to determine AKT activation upon MeSG treatment. <b><i>Results:</i></b> We provide evidence that in all MM cells analyzed, MeSG exerts diverse cytotoxic effects. MeSG treatment of MM.1S and H-929, but not in RPMI-8226, causes a loss of mitochondria membrane potential. MeSG causes an arrest in G₂/M, especially in RPMI-8226, supported by decreased levels of cyclin-B1 and early increased levels of p21. Finally, there is a diverse response to the MeSG treatment for AKT phosphorylation. MM.1S and H-929 showed a marked decrease in AKT phosphorylation at earlier time points compared to the RPMI-8226 line. <b><i>Conclusions:</i></b> MeSG cytotoxicity has been confirmed in all of 3 cell lines studied. Results suggest an early event of increased reactive oxygen species, and/or involvement of cholesterol homeostasis via decreased AKT activation, both of which are currently under investigation.

Knowledge, practices and perceptions regarding oral health preventive measures among Mexican dental students: a cross-sectional survey study

Although oral diseases are mostly preventable, they remain a global public health problem. Thus, there is a need for trained personnel to actively intervene in promoting oral health, to prevent and timeously detect oral diseases, and, in turn, to provide comprehensive quality healthcare. The main objective of the study was to evaluate the knowledge, practices and perceptions regarding oral health preventive measures amongst undergraduate dental students. This cross-sectional study was conducted between the period October 2017 and January 2018. The subjects included were undergraduate students of the dental science program at the School of Dentistry, in Leon Guanajuato, Mexico. A validated questionnaire was used to identify knowledge of preventive dentistry and the frequency of oral health preventive actions in the dental school clinics. Besides, perception towards prevention in dentistry was assessed. A total of N=232 undergraduate students participated of whom 65.9% (N=153) were women. More than half of the students 59.5%, (N=138) rated their knowledge on the prevention of oral diseases as good, followed by 32.8% (N=75) of students who rated it as regular. 49% (N=97) of the students performed frequently preventive treatments in their daily clinical practice. 90% (N=217) think that the main reason of low practice of prevention in dentistry is the lack of commitment of the dentist. 72.8% (N=169) mention that there should be professionals dedicated exclusively to preventive dentistry. Students of second grade demonstrated better prevention knowledge and tended to engage more frequently in preventive activities (p<0.05). In conclusion, our study found that, second-year students perform preventive practices more frequently and these practices decrease as their studies progress. It should be sought to create positive attitudes towards prevention not only in the year in preventive dentistry, but also throughout the entire career. This enables students to become trained professionals that can deliver preventive services to their patients.

Evaluation of Arthrocentesis with hyaluronic acid injections for management of temporomandibular disorders: a systematic review and case series

Although arthrocentesis is an accepted safe treatment modality for the management of temporomandibular disorders (TMD) in symptomatic patients, the benefit of hyaluronic acid (HA) injections remains uncertain. The aim of this study was to evaluate whether intra-articular HA injections adjunctive to arthrocentesis can be more effective than other medications for the improvement of TMD associated symptoms. Additionally, the impact of HA injections on quality of life of TMD patients was assessed with SF-36® questionnaire in a cohort of patients. An electronic search of Medline, Scopus and Cochrane databases was performed up to March 2020. The following search terms were used: "arthrocentesis", "hyaluronic acid", "intra-articular injections", "visco-supplementation", "temporomandibular disorders". Prospective and retrospective studies that reported the application of HA injections compared to other intra-articular drugs for the treatment of temporomandibular disorders were included. Systematic or narrative reviews and pre-clinical studies were excluded. Additionally, a retrospective clinical study was performed for evaluation of changes in quality of life before and after arthrocentesis with HA injections. In the systematic review, the initial search yielded 1327 articles. After screening of the titles, abstracts, and full texts, 29 studies were selected (26 randomized studies, 2 controlled clinical trials, 1 retrospective report). In the clinical study, 12 patients were included. Intra-articular injections of HA and other medications together with arthrocentesis seemed to be beneficial for improvement of functional symptoms of TMD and pain. The case series also supported the efficacy of HA injections showing an improvement of quality of life of these patients. However, from literature review, it was impossible to identify an optimum drug or a protocol for predictably improving the pain and/or functional symptoms of temporomandibular problems, due to different etiologies, diversity of treatment modalities and conflicting results. In conclusion, there is no consensus in the literature that HA injections shows better results in comparison with other treatment modalities. According to the results of the present clinical study, HA injections with/without arthrocentesis seems to be beneficial in terms of clinical symptoms and quality of life of the TMD patients.

Clinical efficacy of grape seed extract as an adjuvant to scaling and root planing in treatment of periodontal pockets

Grape seed extract (GSE), a naturally producing polyphenolic compound, is found to be a potent hostmodulatory agent and considered for management of periodontal disease. Its anti-bacterial, antioxidant, and anti-inflammatory property may aid in achieving periodontal health. To assess the clinical efficacy of GSE in adjunct to scaling and root planing (SRP) in healing of periodontal pockets. The present study was a longitudinal, parallel design, randomized clinical trial. Seventy-two patients (mean age 39.2±8.6 years) with periodontal pockets were randomly divided into two groups; Test group received intra-pocket delivery of GSE with SRP and Control group received SRP alone. The clinical parameters like Plaque Index (PI), Gingival Index (GI), Probing Depth (PD) and Relative Attachment Level (RAL) were recorded at baseline and 3 months. 64 patients completed the study. Test group at the end of 3 months had statistically significant reduced PD (p=0.002) and RAL (p=0.01). No significant difference was observed for PI and GI at the end of 3 months. Intra-pocket application of GSE with SRP could be beneficial in management of periodontal pockets.

Role of probiotics in adjunct to non-surgical periodontal therapy in patients with chronic periodontitis: a systematic review and meta-analysis

The objective of this study was to establish the significance of probiotic usage, both as a preventive as well as a therapeutic strategy for the management of periodontal disease. It also substantiates the existing studies of single/combined bacterial strain for exhibiting variable ecological impact on oral bacteria. Data sources included literature searches of PubMed (MEDLINE), Scopus, Embase, CENTRAL and Web of science databases for placebo controlled randomized clinical trials of SRP with orally administered probiotics in any form as an adjunct. Data extraction was conducted and information from the included studies was tabulated according to the study designs, form of drug delivery, main outcomes, and clinical parameters. Data collected were based on the focused question outlined for the present systematic review. The reviewers cross-checked all extracted data. CAL and PD were assessed as the primary outcome to compare the effectiveness of adjunctive probiotic therapy in addition to SRP. Fourteen clinical studies were included and demonstrated efficacy in reducing periodontal probing depth (PPD) and gaining clinical attachment level (CAL), between probiotics and SRP/placebo. Adjunctive probiotic therapy in addition to SRP leads to decrease in probing depth and clinical attachment gain in chronic periodontitis patients. However, further high-quality randomized clinical trials with microbiological outcomes are required to fortify the conclusion.

Clinical effectiveness of Lactobacillus reuteri in the treatment of peri-implant diseases: a systematic review and meta-analysis

In the last decades, the presence of peri-implant diseases (PD) has increased. One of the therapies currently used is probiotics with Lactobacillus reuteri (LR). The aim of this article is to determinate, through a systematic review and meta-analysis, the clinical effectiveness of LR in the treatment of PD. We searched the literature until January 2021, in the biomedical databases: Pubmed, Embase, Scielo, Science Direct, Scopus, SIGLE, LILACS, Google Scholar and Cochrane Central Registry of Clinical Trials. The selection criteria of the studies were: randomized controlled clinical trials, without language and time restriction, reporting the clinical effects (depth to probing, plaque index and bleeding index) of the LR in the PD treatment. The risk of study bias was analyzed through the Cochrane tool for randomized studies using Review Manager software. The search strategy resulted in 6 articles of which four investigated peri-implantitis and three peri-implant mucositis. All studies reported that there was a difference in the depth of the probing in the treatment of PD, in favor of the group using LR, though not always achieving significance. The use of LR can be clinically effective in terms of pocket depth reduction in the treatment of PD.

Abstract 316: Effect of schweinfurthins on malignant plasma cells

Multiple myeloma (MM), a bone marrow neoplasm is currently incurable and effective alternative therapies are needed. Schweinfurthin-3114 (S-3114) purified from a plant extract, inhibits growth of established MM cell lines. The mechanism(s) for this effect are not fully characterized. To advance understanding, MM cell lines RPMI-8226 and MM.1s were incubated with increasing concentrations of S-3114 for up to 48 hours. S-3114 decreased cell viability (trypan blue assay) and mitochondrial activity (MTT assay) in a concentration and time-dependent manner (p≤0.05). RPMI-8226 cells were more sensitive (EC50 2.36 nM) than MM.1s (EC50 11.1 nM) at 48 hours. Flow cytometry analyses revealed increased apoptosis in a concentration and time-dependent manner in both cell lines (64.0% in RPMI-8226 with 20 nM S-3114; 86.3% in MM.1s with 270 nM S-3114, both at 48 hours). S-3114 also induced cell cycle arrest at G2/M. In RPMI-8226, the percent of cells arrested in G2/M increased from 45.9 to 66.1 with 3.5 nM S-3114 at 24 and 48 hours, respectively. In RPMI-8226, 20 nM S-3114 for 24 and 48 hours caused a 100% G2/M arrest. In both cell lines, S-3114 reduced protein kinase B (Akt) activation (Western blot) in a concentration and time-dependent manner. In MM.1s the apoptotic extrinsic pathway (caspase 8), and not the intrinsic pathway (caspase 9), is highly involved. In fact, S-3114 (20 nM for 48 hours, and 270 nM for 24 and 48 hours) caused a major cleavage for both 43 and 18 KDa caspase 8 fragments. Also cleaved Poly ADP-Ribose Polymerase 1 (PARP-1) increased at S-3114 concentrations of 20 and 270 nM at 24 and 48 hours. S-3114 influence on Golgi-mediated secretion was evaluated by measuring the soluble chemokine Macrophage Inflammatory Protein-1 alpha (MIP-1α), which is secreted by the Golgi and it is involved in the progression of MM disease. S-3114 treatment for 48 hours stimulated the MIP-1α negative cell line (RPMI-8226) to significantly increase MIP-1α RNA levels and to secrete MIP-1α at low concentrations. On the contrary, despite that prolonged S-3114 treatment significantly increased MIP-1α RNA levels, its secretion is decreased in the MIP-1α positive cell line (MM.1s). These in vitro studies demonstrate that S-3114 impairs the Phosphoinositide 3-Kinases (PI3K)/Akt signaling pathway resulting in cell death and/or cell cycle arrest. Data also shows an increased gene expression of the pro-survival MIP-1α by S-3114. Our ongoing studies are focused on schweinfurthin effects on MIP-1 α and Golgi secretion. We postulate that the cytotoxic impact of S-3114 requires disruption of MIP-1α signaling to regulate cell cycle, survival, and impairment of Golgi architecture and secretion in malignant plasma cells. In aggregate, these results reveal mechanism(s) for S-3114 effects and support further work advancing S-3114 as a novel therapy for MM.

Citation Format: Barbara Manfredi, Raymond J. Hohl. Effect of schweinfurthins on malignant plasma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 316.

Nitrogen Containing Bisphosphonates Impair the Release of Bone Homeostasis Mediators and Matrix Production by Human Primary Pre-Osteoblasts

Bisphosphonates (BPs) represent the first-line treatment for a wide array of bone disorders. Despite their well-known action on osteoclasts, the effects they induce on osteoblasts are still unclear. In order to shed light on this aspect we evaluated the impact of two nitrogen containing bisphosphonates, Alendronate (ALN) and Zoledronate (ZOL), on human primary pre-osteoblasts. At first, we showed an inhibitory effect on cell viability and alkaline phosphatase activity starting from µM concentrations of both drugs. In addition, an inhibitory trend on mineralized nodules deposition was observed. Then low doses of both ALN and ZOL rapidly increased the release of the pro-inflammatory mediators TNFα and IL-1β, while increased DKK-1 and Sclerostin, both inhibitors of osteoblastogenesis. Finally, ALN and 10^-7M ZOL decreased the expression of type I Collagen and Osteopontin, while both drugs slightly stimulated SPARC production. With these results, we would like to suggest a direct inhibitory action on bone-forming cells by nitrogen containing bisphosphonates.

Impact of Dental Implant Surface Modifications on Adhesion and Proliferation of Primary Human Gingival Keratinocytes and Progenitor Cells

The success of dental implants depends mainly on osseointegration and gingival sealing. Therefore, early attachment and spreading of epithelial cells might be critical for a positive outcome. Research in dental implant materials has primarily focused on surface roughness, defined by the average roughness (Ra) index, as it promotes the process of osseointegration. This study explored its influence on soft tissue attachment by looking mainly at adhesion, proliferation, and spreading of primary human cells belonging to the epithelial lineage. Characterized human gingival keratinocytes, gingival and epithelial progenitor cells were seeded on machined (S1; Ra = 0.3 to 0.6 μm), Ti-Unite (S2; Ra = 1.2 μm), and SLA (S3; Ra = 2 μm) implants. Cell adhesion with early proliferation and spreading were evaluated by combining a biochemical vitality test with imaging analyses. Findings showed that adhesion was significantly higher on S1 (36% ± 2%) and S2 (44% ± 7%) than on S3 (23% ± 6%), while early proliferation was slightly improved on S1. The resulting data, obtained through an innovative and easily reproducible in vitro method, suggest that implant surface roughness affects epithelial cell adhesion and proliferation.

The Characterization of Monoclonal Antibodies to Mouse TLT-1 Suggests That TLT-1 Plays a Role in Wound Healing

Platelets play a vital role in hemostasis and inflammation. The membrane receptor TREM-like transcript-1 (TLT-1) is involved in platelet aggregation, bleeding, and inflammation, and it is localized in the α-granules of platelets. Upon platelet activation, TLT-1 is released from α-granules both in its transmembrane form and as a soluble fragment (sTLT-1). Higher levels of sTLT-1 have been detected in the plasma of patients with acute inflammation or sepsis, suggesting an important role for TLT-1 during inflammation. However, the roles of TLT-1 in hemostasis and inflammation are not well understood. We are developing the mouse model of TLT-1 to mechanistically test clinical associations of TLT-1 in health and disease. To facilitate our studies, monoclonal murine TLT-1 (mTLT-1) antibodies were produced by the immunization of a rabbit using the negatively charged region of the mTLT-1 extracellular domain ₁₂₂PPVPGPREGEEAEDEK₁₃₉. In the present study, we demonstrate that two selected clones, 4.6 and 4.8, are suitable for the detection of mTLT-1 by western blot, immunoprecipitation, immunofluorescent staining, flow cytometry and inhibit platelet aggregation in aggregometry assays. In addition, we found that the topical administration of clone 4.8 delayed the wound healing process in an experimental burn model. These results suggest that TLT-1 plays an important role in wound healing and because both clones specifically detect mTLT-1, they are suitable to further develop TLT-1 based models of inflammation and hemostasis in vivo.

Activity of a new hydrogen sulfide-releasing aspirin (ACS14) on pathological cardiovascular alterations induced by glutathione depletion in rats

We investigated the effects of the hydrogen sulfide (H₂S)-releasing derivatives of aspirin (ACS14) and salicylic acid (ACS21) in a rat model of metabolic syndrome induced by glutathione (GSH) depletion, causing hypertension and other pathological cardiovascular alterations. GSH depletion was induced in normal rats by the GSH-synthase inhibitor buthionine sulfoximine (BSO, 30 mmol/L day for seven days in the drinking water). Systolic blood pressure and heart rate were measured daily by the tail-cuff method, and plasma thromboxane B₂, 6-keto-prostaglandin F(2α), 8-isoprostane, GSH, insulin and glucose were determined at the end of the seven-day BSO schedule. In addition, ischemia/reperfusion-induced myocardial dysfunction and endothelial dysfunction were assayed on isolated heart and aortic rings, respectively. Unlike aspirin and salicylic acid, ACS14 and ACS21 reduced BSO-induced hypertension, also lowering plasma levels of thromboxane B₂, 8-isoprostane and insulin, while GSH remained in the control range. Neither ACS14 nor ACS21 caused gastric lesions. Both restored the endothelial dysfunction observed in aortic rings from BSO-treated rats, and in ischemia/reperfusion experiments they lowered left ventricular end-diastolic pressure, consequently improving the developed pressure and the maximum rise and fall of left ventricular pressure. Together with this improvement of heart mechanics there were reductions in the activity of creatine kinase and lactate dehydrogenase in the cardiac perfusate. This implies that H₂S released by both ACS14 and ACS21 was involved in protecting the heart from ischemia/reperfusion, and significantly limited vascular endothelial dysfunction in aortic tissue and the related hypertension.

The hydrogen sulphide-releasing derivative of diclofenac protects against ischaemia-reperfusion injury in the isolated rabbit heart

BACKGROUND AND PURPOSE

Hydrogen sulphide (H(2)S) is an endogenous gaseous mediator active in the multilevel regulation of pathophysiological functions in mammalian cardiovascular tissues.

EXPERIMENTAL APPROACH

This study investigated the pharmacological activity of a new H(2)S-releasing derivative of diclofenac, S-diclofenac (2-[(2,6-dichlorophenyl)amino]benzeneacetic acid 4-(3H-1,2-dithiole-3-thione-5-yl)-phenyl ester) in the isolated rabbit heart submitted to low-flow ischaemia-reperfusion damage.

KEY RESULTS

S-diclofenac (3, 10 and 30 microM), despite inhibiting prostacyclin generation by cardiac tissues, achieved dose-dependent normalization of coronary perfusion pressure, reducing left ventricular contracture during ischaemia and improving left ventricular developed pressure and +/-dP/dt(max) at reperfusion. Creatine kinase and lactate dehydrogenase activities in heart perfusates were significantly reduced during reperfusion. These effects were accompanied by substantial release of reduced glutathione (GSH), indicating that the H(2)S moiety may have up-regulated cysteine transport. The anti-ischaemic activities of S-diclofenac and the H(2)S-donor sodium hydro sulphide (NaHS) were partially prevented by the K(ATP) channel antagonist glibenclamide, suggesting a mechanism similar to H(2)S-induced cardioprotection in metabolic ischaemic preconditioning. Perfusion with the nitric oxide (NO) synthase inhibitor N(G)-monomethyl-L-arginine worsened the myocardial ischaemia-reperfusion damage, but this was dose-dependently prevented by S-diclofenac and NaHS, suggesting that the released H(2)S may have overcome NO deficiency.

CONCLUSION AND IMPLICATIONS

These data show that S-diclofenac had marked anti-ischaemic activity in ischaemic-reperfused rabbit hearts despite inhibition of prostaglandin generation. Increased GSH formation leading to activation of K(ATP) channels may have contributed to this beneficial effect. The pharmacological profile of S-diclofenac and its anti-inflammatory activity, with diminished gastrointestinal side effects, offer therapeutic applications in cardiovascular disease.

Sildenafil reduces L-NAME-induced severe hypertension and worsening of myocardial ischaemia-reperfusion damage in the rat

BACKGROUND AND PURPOSE

Phosphodiesterase-5 inhibitors are beneficial in pulmonary hypertension and congestive heart failure, the two conditions associated with coronary heart disease and ischaemia. We investigated whether sildenafil counteracts the cardiovascular alterations induced by N -nitro-L-arginine methyl ester (L-NAME) in the rat.

EXPERIMENTAL APPROACH

Sildenafil was given orally to rats at doses of 0.37, 0.75 or 1.5 mg kg-1day-1 for four weeks, either alone or with L-NAME (35-40 mg kg-1 day-1 in the drinking water). Systolic blood pressure and urinary parameters (6-keto-prostaglandin F1alpha, thromboxane B2, 8-isoprostane-prostaglandin F2 and nitrite/nitrate) were measured in conscious rats. Isolated hearts were subjected to low flow ischaemia-reperfusion, and myocardial levels of guanosine 3', 5'cyclic monophosphate (cGMP) were determined. Endothelial vascular dysfunction was examined in aortic rings.

KEY RESULTS

Sildenafil dose-dependently prevented the rise in systolic blood pressure in L-NAME-treated rats. This activity was associated with a normalization of urinary 8-isoprostane-prostaglandin F2alpha and other biochemical parameters. In perfused hearts, the post-ischaemic ventricular dysfunction was worse in preparations from L-NAME-treated rats than in controls. Sildenafil dose-dependently reduced this effect, and creatine kinase and lactate dehydrogenase release were lower too. cGMP levels, which were low in myocardial tissue from L-NAME-treated rats, were restored by sildenafil. In noradrenaline-precontracted aortic rings from L-NAME-treated rats acetylcholine lost its vasorelaxant effect, and sildenafil restored it.

CONCLUSION AND IMPLICATIONS

In a rat model of chronic nitric oxide deprivation, where hypertension and aggravation of post-ischaemic ventricular dysfunction are associated with loss of vascular endothelium-relaxant function, sildenafil provided significant cardiovascular protection, primarily by maintaining tissue cGMP levels.

Asymmetric dimethylarginine (ADMA) induces vascular endothelium impairment and aggravates post-ischemic ventricular dysfunction in rats

Asymmetric dimethylarginine (ADMA) is an endogenous nitric oxide (NO) inhibitor recognized as an independent risk factor for endothelial dysfunction and coronary heart diseases. This study investigated whether ADMA (10 mg/kg day for 14 days) affected endothelial function and aggravated post-ischemic ventricular dysfunction in the perfused rat heart. Systolic blood pressure and heart rate, plasma levels of ADMA and nitrite/nitrate were measured in vehicle- and ADMA-treated rats. Perfused hearts were submitted to global ischemia-reperfusion and vascular endothelial dysfunction was examined with angiotensin II in coronary vessels and aortic rings. Endothelial NO synthase (eNOS) and angiotensin-converting enzyme (ACE) mRNA expression in aortic and cardiac tissues were measured. ADMA-treated rats had higher systolic blood pressure (1.3-fold, P<0.01) and slower heart rate (16%, P<0.05) than controls. Plasma ADMA rose (1.9-fold, P<0.01) and nitrite/nitrate concentration decreased 59% (P<0.001). Ventricular contraction (stiffness) increased significantly, with worsening of post-ischemic ventricular dysfunction. In preparations from ADMA-treated rats the coronary vasculature's response to angiotensin II was almost doubled (P<0.01) and the maximal vasorelaxant effect of acetylcholine in aortic rings was significantly lower than in preparations from vehicle-treated rats. In cardiac and aortic tissues eNOS mRNA and ACE mRNA levels were similar in controls and ADMA-treated rats. The increased plasma levels of ADMA presumably cause endothelial dysfunction because of a deficiency in NO production, which also appears involved in the aggravation of myocardial ischemia-reperfusion injury.

Nefopam is more potent than carbamazepine for neuroprotection against veratridine in vitro and has anticonvulsant properties against both electrical and chemical stimulation

Nefopam (NEF) is a known analgesic that has recently been shown to be effective in controlling both neuropathic pain and convulsions in rodents. In this study we compared nefopam to carbamazepine (CBZ), a reference antiepileptic drug (AED), for their ability to protect cerebellar neuronal cultures from neurodegeneration induced by veratridine (VTD). Furthermore, we tested nefopam for protection against both, maximal electroshock-induced seizures (MES), and isoniazid-induced seizures in mice. Both NEF and CBZ were effective in preventing both signs of excitotoxicity and neurodegeneration following exposure of cultures to 5 microM veratridine for 30 min and 24 h, respectively. Concentrations providing full neuroprotection were 500 microM CBZ and 50 microM NEF, while the concentration providing 50% neuroprotection was 200 microM for CBZ and 20 microM for NEF. Neither NEF nor CBZ reduced excitotoxicity following direct exposure of cultures to glutamate, but CBZ failed to reduce increases in intracellular calcium following stimulation of L-type voltage sensitive calcium channels. In vivo, NEF (20 mg/kg i.p.) significantly reduced MES and fully prevented MES-induced terminal clonus (TC). In comparison, NEF was significantly more effective than CBZ in preventing MES, although both drugs were equally effective against MES-induced TC. Furthermore, nefopam provided protection against isoniazid-induced seizures at doses similar to those protecting against MES.

Positive interaction of the novel beta2-agonist carmoterol and tiotropium bromide in the control of airway changes induced by different challenges in guinea-pigs

This study evaluated the bronchodilating activity of the beta(2)-agonist carmoterol and the muscarinic M(3)-antagonist tiotropium, given intratracheally alone or in combination in anaesthetized artificially ventilated normal and actively sensitized guinea-pigs. Carmoterol (0.3-100pmol) and tiotropium (10-1000pmol) were superfused (0.01ml/min) for 5min before challenges with acetylcholine (20mug/kg i.v.), histamine (10mug/kg i.v.) or ovalbumin (5mg/kg i.v.). Both compounds given alone were markedly active against all the challenges. Tiotropium resulted more effective towards cholinergic challenge and carmoterol was very potent against histamine and ovalbumin-induced reaction, being effective already at 1pmol. In the presence of tiotropium, the bronchodilating activity of carmoterol was significantly augmented. The ED(50) value of carmoterol on the acetylcholine challenge was reduced by about 10 and 28 times (0.1 and 0.3pmol of tiotropium), that on the histamine one by 4.5 and 13 times (1 and 3pmol of tiotropium) and that on the ovalbumin-induced one by 8 and 25 times (10 and 30pmol of tiotropium). A positive interaction was also evident when other parameters were evaluated. The histamine-induced release of thromboxane B(2) was markedly reduced (56%, P<0.001) by combining completely ineffective doses of the two drugs (0.3 and 3pmol for carmoterol and tiotropium, respectively). In ovalbumin-challenged animals the time to death, amounting in control animals to 7.2+/-0.9min, was dose-dependently prolonged up to achieve complete protection from death with combination of 1 and 30pmol of carmoterol and tiotropium, respectively. The favorable interaction between carmoterol and tiotropium can represent a good option in the control of bronchopulmonary diseases marked by an increase of airway resistances.

Nitric oxide and prostacyclin pathways: an integrated mechanism that limits myocardial infarction progression in anaesthetized rats

Nitric oxide (NO) and cyclooxygenase-derived prostaglandins, such as prostacyclin (PGI2), are involved in vascular homeostasis. To better understand the reciprocal role of both NO and PGI2 on myocardial infarction in the rat, we have investigated the cardioprotective effect of nitro-naproxen, isosorbide dinitrate (ISDN), L-arginine, defibrotide and naproxen. In this study, male Wistar rats were treated orally once a day for 5 consecutive days with the compounds under investigation and then, under anesthesia, the animals were subjected to acute myocardial ischemia (30 min) and reperfusion (120 min). Systemic blood pressure, left ventricular pressure and related parameters of cardiac mechanics were recorded. Ventricular arrhythmias and infarct size of the left ventricular wall were also evaluated. Furthermore, cardiac myeloperoxidase (MPO) and plasma creatine phosphokinase (CPK) activities were determined. Defibrotide, nitro-naproxen, ISDN and L-arginine all provided a cardioprotection characterized by significant prevention of arrhythmias with high survival rate of the rats. Infarct size restriction was paralleled by reduction of both cardiac MPO and plasma CK. Cardioprotection of nitro-naproxen, ISDN and L-arginine involve nitrites/nitrates and PGI2-increased in the circulation associated to a reduction of thromboxane B2 (TXB2) in the blood. Defibrotide displays a cardioprotection by increasing PGI2 release and by reducing TXB2 in the blood. Naproxen was devoid a lower protecting activity on myocardial infarction, and PGI2 inhibition may have played a critical role in this context. The results suggested that the increase of both NO and PGI2 brings about a cascade of integrated cellular and molecular events which are of paramount importance in prevention of myocardial ischemic insult.

Angiotensin II type 1 receptor antagonism improves endothelial vasodilator function in L-NAME-induced hypertensive rats by a kinin-dependent mechanism

OBJECTIVE

This study was designed to investigate the ability of a chronic blockade of angiotensin II type 1 receptors with losartan to reverse the endothelial dysfunction present in N-nitro-L-arginine methyl ester (L-NAME)-treated hypertensive rats and the possible dependence of this effect on bradykinin B2-receptor activation.

METHODS

Rats treated with L-NAME alone (60 mg/kg per day for 8 weeks) or with L-NAME + losartan, L-NAME + icatibant (a bradykinin B2-receptor antagonist) and L-NAME + losartan + icatibant were studied. Losartan, icatibant or losartan + icatibant were co-administered with L-NAME during the last 4 weeks of the experiment. Endothelial nitric oxide synthase gene expression in aortic tissues, plasma nitrite/nitrate concentrations, the relaxant effect of acetylcholine on norepinephrine-precontracted aortic rings and 6-keto-PGF1alpha release from aortic rings were used as markers of the endothelial function.

RESULTS

Rats treated with L-NAME alone and L-NAME + icatibant showed, as compared with untreated animals, a clear-cut increase in systolic blood pressure and a decrease of all the markers of endothelial function evaluated. In L-NAME-rats, administration of losartan reduced the systolic blood pressure and restored endothelial nitric oxide synthase gene expression, plasma nitrite/nitrate levels, the relaxant activity of acetylcholine on aortic rings and the generation of 6-keto-PGF1alpha from the aortic tissues. Co-administration of icatibant with losartan blunted the stimulatory effect of losartan on the markers of endothelial function evaluated.

CONCLUSION

These results demonstrated that losartan is capable of reversing the endothelial vasodilator dysfunction in L-NAME-induced hypertensive rats, and that the beneficial effect of losartan is mediated by bradykinin B2-receptor activation.

Positive interaction of the beta2-agonist CHF 4226.01 with budesonide in the control of bronchoconstriction induced by acetaldehyde in the guinea-pigs

Pretreatment of anaesthetized guinea-pigs with either CHF 4226.01 (8-hydroxy-5-[(1R)-1-hydroxy-2-[N-[(1R)-2-(p-methoxyphenyl)-1-methylethyl]amino]ethyl] carbostyril hydrochloride), formoterol or budesonide reduced acetaldehyde (AcCHO)-evoked responses in the lungs with a rank order of potency CHF 4226.01 (ED(50) values, from 1.88 to 3.31 pmol) > formoterol (ED(50) values, from 3.03 to 5.51 pmol) >> budesonide (ED(50) values, from 335 to 458 nmol). The duration of action of CHF 4226.01 in antagonizing the airway obstruction elicited by AcCHO was also substantially longer than formoterol (area under the curve) at 10 pmol, 763+/-58 and 480+/-34, respectively; P<0.01). Continuous infusion of a subthreshold dose of AcCHO enhanced the intratracheal pressure (ITP) increases caused by subsequent challenges with substance P (from 9.7+/-0.8 to 27.5+/-1.6 cm H(2)O as a peak, P<0.001). Pretreatment with either CHF 4226.01 or formoterol prevented the sensitizing effect of AcCHO on substance P responses (ED(50) values, 2.85 and 6.11 pmol, respectively; P<0.01). The ED(50) value of budesonide (396 nmol) in preventing AcCHO-evoked ITP increase was reduced when this glucocorticoid was combined with 0.1 pmol CHF 4226.01 (ED(50) 76 nmol; P<0.001). CHF 4226.01/budesonide was two-fold more effective (P<0.01) than the formoterol/budesonide combination. These results suggest that CHF 4226.01/budesonide, by optimizing each other's beneficial potential in the control of pulmonary changes caused by AcCHO in the guinea-pigs, may represent a new fixed combination in asthma.

Angiotensin-converting enzyme inhibition and angiotensin AT1-receptor antagonism equally improve endothelial vasodilator function in l-NAME-induced hypertensive rats

Male Sprague-Dawley rats given N(omega)-nitro-L-arginine methyl ester (L-NAME) in drinking water for 8 weeks showed: (1) a clear-cut increase in systolic blood pressure; (2) a consistent decrease of endothelial-cell nitric oxide synthase (eNOS) gene expression in aortic tissue; (3) a marked reduction of plasma nitrite/nitrate concentrations; (4) a reduction of the relaxant activity of acetylcholine (ACh, from 10(-10) to 10(-4) M) on norepinephrine-precontracted aortic rings (reduction by 48+/-5%); (5) a marked decrease (-58%) of the basal release of 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha) from aortic rings. In L-NAME-treated rats, administration in the last 4 weeks of either the angiotensin-converting enzyme (ACE) inhibitor enalapril (10 mg/kg/day in tap water) or the angiotensin AT(1)-receptor antagonist losartan (10 mg/kg/day in tap water) decreased systolic blood pressure levels, completely restored eNOS mRNA levels in aortic tissue and plasma nitrite/nitrate levels, and allowed a consistent recovery of both the relaxant activity of acetylcholine and the generation of 6-keto-PGF1alpha. Coadministration of icatibant, a bradykinin B(2)-receptor antagonist (200 microg/kg/day), with enalapril blunted the stimulatory effect of the ACE inhibitor on eNOS mRNA expression, circulating levels of nitrite/nitrate, the relaxant activity of ACh and the release of 6-keto-PGF1alpha in L-NAME-treated rats. The generation of 6-keto-PGF1alpha from aortic rings was also decreased in rats coadministered icatibant with losartan. These findings indicate that (1) the ACE inhibitor enalapril and the angiotensin AT(1)-receptor blocker losartan are equally effective to reverse NAME-induced endothelial dysfunction; (2) the beneficial effect of enalapril on the endothelial vasodilator function in L-NAME-treated rats is mediated by bradykinin B(2)-receptor activation; and (3) the enhanced endothelial generation of prostacyclin induced by losartan in L-NAME rats is also mediated by bradykinin B(2)-receptor activation.

Nitric oxide-releasing aspirin inhibits vasoconstriction in perfused tail artery of normotensive and spontaneously hypertensive rats

The aim of this study was to investigate the capacity of the 2-(acetyloxy)benzoic acid 3-(nitrooxymethyl)phenyl ester (NCX 4016), a nitric oxide (NO)-releaser derivative of aspirin, to decrease blood pressure in spontaneously hypertensive rats (SHR) and to counteract the adrenergic vasoconstriction in perfused tail artery of these animals. Oral treatment for 10 consecutive days with NCX 4016 (100 micromol/kg) in SHR and their genetic controls Wistar Kyoto (WKY) rats resulted in a reduction of blood pressure in SHR but not in WKY rats. In SHR, the NCX 4016 treatment increased the serum nitrite/nitrate and diminished the serum thromboxane B2, whereas aspirin did not change blood pressure but abolished the serum thromboxane B2. Perfused tail arteries excised from vehicle-treated SHR exhibited a significant impairment of endothelium-dependent vasorelaxant function. These vessels, prepared from SHR or WKY rats treated orally with NCX 4016 (10, 30 and 100 micromol/kg for 7 consecutive days), revealed a dose-dependent decrease in vasoconstriction in response to transmural nerve stimulation and norepinephrine, whereas aspirin was ineffective. Furthermore, in tail arteries of both SHR and WKY rats treated orally with NCX 4016 (100 micromol/kg for 7 consecutive days), the cGMP increased significantly. In conclusion, NCX 4016, by releasing NO and increasing cGMP in vascular tissue, reduces sympathetic-mediated vasoconstriction in resistance vessels and lowers blood pressure in SHR.

The Nitric Oxide-Releasing Naproxen Derivative Displays Cardioprotection in Perfused Rabbit Heart Submitted to Ischemia-Reperfusion

In this study, the pharmacological activity of HCT-3012 [(S)-6-methoxy-alpha-methyl-2-naphtaleneacetic acid 4-(nitrooxy)butyl ester], a nitric oxide (NO)-releasing derivative of naproxen, was compared with that of naproxen in a model of acute ischemia (40 min) and reperfusion (20 min) of the rabbit heart. HTC-3012 (3-100 microM), in spite of inhibition of 6-keto-prostaglandin F(1alpha) generation by the cardiac tissues, brought about a dose-dependent normalization of coronary perfusion pressure, associated with a reduction of ventricular contracture during ischemia with remarkable improvement of left ventricular developed pressure at reperfusion. These beneficial effects were accompanied by a substantial release of nitrite/nitrate in the heart perfusates, indicating that NO has been released by HCT-3012 and donated to the cardiac tissue. These events were paralleled by a significant reduction of creatine kinase activity in heart perfusates during reperfusion. Naproxen (10-100 microM) aggravated the myocardial damage in ischemic reperfused hearts, severely depressing the postischemic ventricular dysfunction. Perfusion of the heart with N(G)-monomethyl-l-arginine (10 microM) caused a marked aggravation of myocardial damage of the reperfused hearts, and this effect was dose dependently prevented by HCT-3012 but not by naproxen. The results of the present experiments clearly indicate that HCT-3012, by donating NO, displays a noticeable anti-ischemic effect in reperfused ischemic rabbit hearts. The safer gastrointestinal profile of HCT-3012 and its ability to control experimental hypertension, suggest that this compound may have therapeutical potential in cardiovascular disease, namely in the prevention of myocardial ischemic events, and may represent a better alternative to conventional nonsteroidal anti-inflammatory drugs.

Nefopam, an analogue of orphenadrine, protects against both NMDA receptor-dependent and independent veratridine-induced neurotoxicity

Nefopam hyghochloride is a potent analgesic compound commercialized in most Western Europe for 20 years, which possesses a profile distinct from that of opioids or anti-inflammatory drugs. Previous evidence suggested a central action of nefopam but the detailed mechanisms remain unclear. While, nefopam structure resembles that of orphenadrine, an uncompetitive NMDA receptor antagonist, here we report that differently from orphenadrine, nefopam (100 microM) failed to protect cultured cerebellar neurons from excitotoxicity following direct exposure of neurons to glutamate. Moreover, nefopam failed to displace MK-801 binding to hippocampal membranes. Nefopam effectively prevented NMDA receptor-mediated early appearance (30 min) of toxicity signs induced by the voltage sensitive sodium channel (VSSC) activator veratridine. The later phase (24 h) of neurotoxicity by veratridine occurring independently from NMDA receptor activation, was also prevented by nefopam. Nefopam effect was not mimicked by the GABA receptor agonist muscimol.

The aminotetraline derivative (+/-)-(R,S)-5,6-dihydroxy-2-methylamino-1,2,3,4-tetrahydro-naphthalene hydrochloride (CHF-1024) displays cardioprotection in postischemic ventricular dysfunction of the rat heart

To analyze the protective effects of the aminotetraline derivative (+/-)-(R,S)-5,6-dihydroxy-2-methylamino-1,2,3,4-tetrahydro-naphthalene hydrochloride (CHF-1024), a compound endowed with DA2-dopaminergic/alpha2-adrenergic receptor agonistic activity, in myocardial ischemia/reperfusion damage. A model of isolated and perfused (15 ml/min) electrically driven (300 beats/min) rat heart subjected to global ischemia (1 ml/min for 20 min) and reperfusion (15 ml/min for 30 min) was followed. Cardiac mechanics changes were evaluated together with biochemical markers of cardiac ischemia in perfusate and tissue tumor necrosis factor-alpha (TNF-alpha). CHF-1024, perfused through the heart for 15 min before ischemia at different molar concentrations (1-100 nM), significantly improved left ventricle developed pressure during reperfusion, and normalized left ventricular end-diastolic pressure and coronary perfusion pressure. This anti-ischemic effect of CHF-1024 was associated to a decrease in creatine kinase and lactate dehydrogenase, both released during heart reperfusion. These events were concomitant with maintenance of a higher production of 6-keto-prostaglandin F1alpha The ability of CHF-1024 to improve postischemic ventricular dysfunction was correlated with a dose-dependent inhibition of the release of both norepinephrine (NE), from sympathetic nerve endings, and TNF-alpha from cardiac tissue. The effect of CHF-1024 on NE release was almost completely antagonized by specific antagonists of presynaptic inhibitory receptors domperidone and rauwolscine. The finding that this new aminotetraline derivative possesses anti-ischemic properties and limits NE release from cardiac nerve endings may bear some therapeutic potential in cardiovascular diseases.

Neuronal sensitization and its behavioral correlates in a rat model of neuropathy are prevented by a cyclic analog of orphenadrine

N-methyl-D-aspartic acid (NMDA) is an agonist at the homonymous receptor implicated in the development of neuronal sensitization and its behavioral correlates. An effective modulation of the NMDA effects, achieved also by uncompetitive antagonists, could contribute to controlling pain symptoms in several neuropathic syndromes. Because nefopam is a known analgesic derivative of orphenadrine and of its congener diphenhydramine, both uncompetitive NMDA receptor antagonists, we tested the effect of nefopam on the developing pain and neuronal anomalies in an animal model of chronic pain with NMDA receptor involvement. A single intraperitoneal injection of nefopam was administered twenty minutes prior to the chronic constriction injury of the sciatic nerve (CCI rats). In the first 10 days, nefopam (30 mg/kg) significantly decreased behavioral signs of neuropathic pain and the stimulus-evoked electrophysiological anomalies in recordings at 14 days, with only slight manifestation afterwards. The dose of 20 mg/kg was ineffective. Nefopam injected after constriction was ineffective. In normal non-operated rats, Nefopam had no effect on the electrophysiological and behavioral parameters. Iontophoretic nefopam (1 mM, 50-80 nA, positive current) in normal rats did not change the spontaneous neuronal activity, but reduced the mean response to noxious stimuli and the concurrent iontophoretic NMDA evoked activity. In CCI rats, iontophoretic nefopam did not significantly modify the spontaneous hyperactivity but reduced significantly both the frequency of the responses to noxious stimuli, and the duration of the afterdischarge. We propose that nefopam exerts a preventive analgesic effect, with a possible role in modulating NMDA receptor-mediated effects in central sensitization.

Procyanidins from Vitis vinifera seeds display cardioprotection in an experimental model of ischemia-reperfusion damage

Since the early 1970s, increasing evidence has suggested that the consumption of moderate amounts of alcohol is inversely correlated with mortality from myocardial infarction. There is also some evidence that the protective effects of wine might be more pronounced than those of other alcoholic beverages. These observations prompted us to investigate the cardioprotective activity of Vitis vinifera seeds in experimental ischemia-reperfusion injury. An isolated rabbit heart preparation paced electrically was used to evaluate the effects of a highly purified, high molecular weight fraction of oligomeric procyanidins isolated from Vitis vinifera seeds on myocardial reperfusion injury after 40 min of low-flow (1 ml/min) ischemia. Infusion of the heart with 100 or 200 microg/ml procyanidins dose-dependently reduced left ventricular end-diastolic pressure during ischemia, decreased coronary perfusion pressure, improved cardiac mechanical performance upon reperfusion, increased the release of 6-Keto-prostaglandin F1alpha into the perfusate in both the preischemic and the reperfusion periods and suppressed rhythm irregularity. Procyanidins dose-dependently relaxed human internal mammary aortic (IMA) rings (with intact endothelium) precontracted with norepinephrine. This effect was completely abolished in IMA-rings without functional endothelium or when this vascular tissue was pretreated with nitric oxide synthase inhibitor (NG-monomethyl-L-arginine) or with guanylate cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one). In conclusion, these results indicate that procyanidins could be of therapeutical potential in cardiovascular diseases. However, further investigations are required for a better definition of the mode of action of these oligomers.

NCX 4016, a nitric oxide-releasing aspirin, modulates adrenergic vasoconstriction in the perfused rat tail artery

1. The ability of the nitric oxide (NO)-releasing aspirin, NCX 4016, to control vasoconstrictor responses induced by electrical field stimulation (TNS) or by exogenous norepinephrine (NE) was investigated in perfused rat tail artery with intact endothelium. 2. NCX 4016 (25, 50 and 100 microM) dose-dependently antagonized the vasoconstriction caused by TNS (from 0.5 to 64 Hz) and by NE (from 0.01 to 10 microM). The vasorelaxant activity of NCX 4016 (100 microM) in NE-precontracted arteries was concomitant with a marked increase of tissue cyclic GMP (4.9 fold, P<0.001) and was significantly antagonized by the inhibitors of soluble guanylate cyclase, methylene blue and 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one. 3. The effect of NCX 4016 was endothelium NO-independent since, in preparations perfused with N(G)-monomethyl-L-arginine (10 microM), this compound prevented the rise in basal perfusion pressure and reversed the accentuation of vasoconstrictor responses caused by NO synthase inhibition. 4. Aspirin-moiety released by NCX 4016 inhibited the 6-keto-PGF(1alpha) formation without interfering with the vasorelaxant activity of NCX 4016, while aspirin (100 microM) was devoid of any activity against vasoconstriction induced by both TNS and NE in perfused rat tail artery. 5. NCX 4016 moderated adrenergic vasoconstriction in perfused rat tail arteries by a direct donation of NO without involving the relaxant factors such as PGI(2) and NO from endothelial cells. 6. The results obtained with NCX 4016 in perfused rat tail artery bears some therapeutical potential in conditions associated with vascular smooth muscle hyperreactivity to adrenergic stimulation.

Enalapril and quinapril improve endothelial vasodilator function and aortic eNOS gene expression in L-NAME-treated rats

Endothelial dysfunction ensuing inhibition of nitric oxide synthase (NOS) was investigated in male Sprague-Dawley rats given N(omega)-nitro-L-arginine methyl ester (L-NAME) in drinking water for 8 weeks. Age-matched rats served as controls. L-NAME-treated rats, as compared to control animals, showed: (1) a clear-cut increase in systolic blood pressure; (2) a consistent decrease of endothelial-cell NOS (eNOS) gene expression in aortic tissue; (3) a reduction of the relaxant activity of acetylcholine (ACh, from 10(-10) to 10(-4) M) on norepinephrine-precontracted aortic rings (reduction by 52+/-5%); (4) a marked decrease (-50%) of the basal release of 6-keto-prostaglandin F(1 alpha) (6-keto-PGF(1 alpha)) from aortic rings. In L-NAME-treated rats, administration in the last 2 weeks of either the angiotensin-converting enzyme inhibitor enalapril (1 mg/kg/day) or the cognate drug quinapril (1 mg/kg/day) decreased systolic blood pressure levels, completely restored eNOS mRNA levels in aortic tissue, and allowed a consistent recovery of both the relaxant activity of ACh and the generation of 6-keto-PGF(1 alpha). No difference was present in the ability of the two angiotensin-converting enzyme inhibitors to reverse NAME-induced endothelial dysfunction. These findings indicate that L-NAME-induced hypertension in the rat relies on the marked impairment of the endothelial vasodilator function, with an ensuing contribution by a decreased production of prostacyclin by the endothelial cells. Angiotensin-converting enzyme inhibition by enalapril or quinapril was equally effective in improving endothelial vasodilator function, prostacyclin endothelial production and restoring aortic eNOS mRNA.

Novel effect of nefopam preventing cGMP increase, oxygen radical formation and neuronal death induced by veratridine

Nefopam hydrochloride is a potent analgesic compound that possesses a profile distinct from that of opiods or anti-inflammatory drugs. Previous evidence suggested a central action of nefopam but the detailed mechanisms remain unclear. Here we have used cultured cerebellar neurons to test the hypothesis that nefopam may modulate voltage sensitive sodium channel (VSSC) activity. Nefopam (100 microM) effectively prevented NMDA receptor-mediated early appearance (30 min) of toxicity signs induced by the VSSC activator veratridine. Delayed neurotoxicity by veratridine occurring independently from NMDA receptor activation, was also prevented by nefopam. In contrast, excitotoxicity following direct exposure of neurons to glutamate was not affected. Neuroprotection by nefopam was dose-dependent. 50% protection was obtained at 57 microM while full neuroprotection was achieved at 75 microM nefopam. Veratridine-induced sodium influx was completely abolished in nefopam-treated neurons. Intracellular cGMP and oxygen radical formation following VSSC stimulation by veratridine were also effectively prevented by nefopam. Our data are consistent with an inhibitory action of nefopam on VSSC and suggest that nefopam may modulate the release of endogenous glutamate following activation of these channels. This novel action of nefopam may be of great interest for the treatment of neurodegenerative disorders involving excessive glutamate release and neurotransmission.

Comparison of endothelium-dependent vasoactivity of internal mammary arteries from hypertensive, hypercholesterolemic, and diabetic patients

BACKGROUND

Endothelium-dependent relaxation is abnormal in a variety of diseased states. Despite the widespread use of the internal mammary artery (IMA) in coronary artery bypass grafting, there is a lack of comparative studies on IMA endothelial-dependent function in patients with major cardiovascular risk factors.

METHODS

An IMA segment from 48 selected patients undergoing coronary artery bypass grafting was harvested intraoperatively and assigned to one of four groups (n = 12): diabetics requiring therapy, hypertensives, hypercholesterolemic, and nondiabetic-normotensive-normocholesterolemic patients. Internal mammary artery specimens were cut into rings and suspended in organ bath chambers, and the isometric tension of vascular tissues was recorded. The IMA rings were (1) precontracted with norepinephrine, and the endothelium-derived relaxation was evaluated by cumulative addition of acetylcholine, (2) contracted with cumulative concentrations of endothelin-1, and (3) contracted with the nitric oxide synthase inhibitor, N(G)-monomethyl-L-arginine. Furthermore, the release of prostacyclin by the IMA rings was directly measured during basal tone conditions and at the end of the various pharmacologic interventions. Histology of IMA rings was randomly performed.

RESULTS

The results obtained in these experiments showed that IMA rings harvested from hypertensive patients have the greatest impairment of endothelium-dependent response to relaxant and contracting stimuli (p < 0.01 versus nondiabetic-normotensive-normocholesterolemic tissues; p < 0.05 versus hypercholesterolemic and diabetic tissues) and prostacyclin release in normal and stimulated conditions. To a lesser extent, hypercholesterolemic and diabetic tissues show similar depression (diabetic > hypercholesterolemic) both of relaxation and prostacyclin production, with respect to nondiabetic-normotensive-normocholesterolemic specimens (p < 0.05). Histology findings (scanning electron microscopy) did not differ in multiple sections from vessel studies.

CONCLUSIONS

Major cardiovascular risk factors affect the endothelium-dependent vasoactive homeostasis of human IMA differently. Depression of relaxation is highest in patients with a history of hypertension. These findings may be pertinent to early and long-term treatment of patients undergoing coronary artery bypass grafting.

The nitroderivative of aspirin, NCX 4016, reduces infarct size caused by myocardial ischemia-reperfusion in the anesthetized rat

NCX 4016, a nitro-ester of aspirin endowed with antithrombotic activity, appears to have clinical potential in treating cardiac complications related to coronary insufficiency. This compound has been shown to improve postischemic ventricular dysfunction and to reduce myocardial infarct size in the rabbit. The cardioprotection conferred by NCX 4016 (10, 30, and 100 mg/kg) and aspirin (ASA, 54 mg/kg) was evaluated in anesthetized rats subjected to 30 min of myocardial ischemia followed by 120 min of reperfusion (MI/R). Drugs were given orally for 5 consecutive days. NCX 4016 displayed remarkable cardioprotection in rats subjected to MI/R as was evident in the reduction of ventricular premature beats and in the incidence of ventricular tachycardia and fibrillation; they were reduced dose dependently and correlated with survival of all rats treated with the higher dose of NCX 4016. In these animals, infarct size was restricted proportionally to the dose of NCX 4016 associated with diminution of both plasma creatine phosphokinase and cardiac myeloperoxidase activities. ASA showed only a minor degree of protection against MI/R damage. Rats treated with N(G)-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg) demonstrated aggravated myocardial damage in terms of arrhythmias, mortality, and infarct size. Supplementation of nitric oxide (NO) with NCX 4016 (100 mg/kg) greatly reduced the worsening effect caused by L-NAME. The beneficial effects of NCX 4016 appear to derive in large part from the NO moiety, which modulates a number of cellular events leading to inflammation, obstruction of the coronary microcirculation, arrhythmias, and myocardial necrosis.

Novel antioxidant agents deriving from molecular combinations of vitamins C and E analogues: 3,4-dihydroxy-5(R)

Molecular combinations of two antioxidants (i.e., ascorbic acid and the pharmacophore of alpha-tocopherol), namely the 2,3-dihydroxy-2,3-enono-1,4-lactone and the chromane residues, have been designed and tested for their radical scavenging activities. When evaluated for their capability to inhibit malondialdehyde (MDA) production in rat liver microsomal membranes, the 3,4-dihydroxy-5R-2(R,S)-(6-hydroxy-2,5,7,8-tetramethylchroman-2(R,S)yl-methyl)-1,3]dioxolan-4S-yl]-5H-furan-2-one (11a-d), exhibited an interesting activity. In particular the 5R,2R,2R,4S and 5R,2R,2S,4S isomers (11c,d) displayed a potent antioxidant effect compared to the respective synthetic alpha-tocopherol analogue (5) and natural alpha-tocopherol or ascorbic acid, used alone or in combination. Moreover, the mixture of stereoisomers 11a-d also proved to be effective in preventing damage induced by reperfusion on isolated rabbit heart, in particular at the higher concentration of 300 microM. In view of these results our study represents a new approach to potential therapeutic agents for applications in pathological events in which a free radical damage is involved. Design, synthesis and preliminary biological activity are discussed.

The effects of tramadol and morphine on immune responses and pain after surgery in cancer patients

There has been growing interest in determining the possible immune consequences of opioid administration for the management of postoperative pain. We studied the effects of morphine and tramadol on pain and immune function during the postoperative period in 30 patients undergoing abdominal surgery for uterine carcinoma. Phytohemoagglutinin-induced T lymphocyte proliferation and natural killer cell activity were evaluated immediately before and after surgery, and 2 h after the acute administration of either 10 mg of morphine IM or 100 mg tramadol IM for pain. In all patients, phytohemagglutinin-induced lymphoproliferation was significantly depressed by surgical stress. However, in the morphine-treated group, proliferative values remained lower than basal levels for 2 h after treatment, whereas in tramadol-administered patients proliferative values returned to basal levels. Natural killer cell activity was not significantly affected by surgery nor by morphine administration, whereas tramadol significantly enhanced the activity of natural killer cells. Both drugs produced a comparable reduction in postoperative pain. We conclude that, as previously observed in the experimental animal, tramadol and morphine, when administered in analgesic doses, induce different immune effects.

IMPLICATIONS

Recent studies suggest that opioids can have an adverse impact on the immune system. Because surgical stress also induces immune dysfunction, the search for analgesic drugs devoid of immunosuppressive effects is of import. This study compared the effects on immune responses of morphine and of the atypical opioid analgesic, tramadol, given for postoperative pain to gynecological cancer patients. Tramadol and morphine showed comparable analgesic activity; however, tramadol, in contrast to morphine, induced an improvement of postoperative immunosuppression and, therefore, may be preferred to morphine for the treatment of postoperative pain.

The opioid antagonist naloxone induces a shift from type 2 to type 1 cytokine pattern in BALB/cJ mice

Opioid peptides affect different immune functions. We present evidence that these effects could be mediated by the modulation of T(H)1/T(H)2 cytokine production. BALB/cJ mice were immunized with 50 or 100 microg of the protein antigen keyhole-limpet hemocyanin (KLH), and treated acutely or chronically with the opioid antagonist naloxone. One and 2 weeks after immunization, the production of cytokines by splenocytes was evaluated by in vitro restimulation with KLH. The acute and chronic treatment with the opioid receptor antagonist naloxone decreased the production of interleukin (IL)-4 by splenocytes of BALB/cJ mice. In contrast, IL-2 and interferon-gamma levels increased after naloxone treatment. Finally, the opioid antagonist diminished the serum immunoglobulin G anti-KLH antibody titers. These results suggest that naloxone increases T(H)1 and decreases T(H)2 cytokine production. The effect of naloxone could be ascribed to the removal of the regulatory effects exerted by endogenous opioid peptides, which could therefore activate T(H)2 and suppress T(H)1 cytokines. (Blood. 2000;95:2031-2036)