Nimodipine does not affect the flow–metabolism couple in permanent cerebral ischemia

Despite widespread investigational and clinical usage of the calcium channel blocker nimodipine, its effects on cerebral physiology in normal and ischemic brain remain poorly understood. In order to gain insight into this subject we examined the effects of nimodipine on glucose metabolism and cerebral blood flow–metabolism coupling in the rat during conditions of reproducible focal ischemia. Nimodipine-treated animals were then matched with vehicle-treated controls for both study conditions. Animals were subjected to permanent occlusion of the middle cerebral artery (MCA) along with occlusion of the common carotid arteries. Five minutes into ischemia, an intravenous infusion of nimodipine (1 µg/kg per min, n=9) or vehicle (n=9) was initiated and continued until the end of the study. Seventy-five minutes after the occlusion, [¹⁴C]2-deoxyglucose was injected into the venous catheter for the measurement of the local cerebral metabolic rate for glucose (LCMRgl), followed 25 min later by the injection of N-isopropyl-[¹²³I]p-iodoamphetamine for the measurement of local cerebral blood flow (LCBF). The animals were killed at the end of 2 h of ischemia, and the brains were processed for double-labeled autoradiography. In all animals, permanent MCA occlusion produced significant decrements in LCBF, LCMRgl, and LCBF/LCMRgl ratio in both the core of the ischemia as well as regions peripheral to the ischemia within the same cerebral hemisphere when compared with non-ischemic brain. There were no significant differences between the nimodipine-treated and vehicle-treated groups. In conclusion, nimodipine does not appear to alter cerebral blood flow or cerebral metabolism in ischemic brain.     

Chronic nicotine exposure inhibits 17β-estradiol-mediated protection of the hippocampal CA1 region against cerebral ischemia in female rats

Nicotine addiction in women increases the risk of ischemic stroke. Importantly, women who smoke and use hormone replacement therapy/oral contraceptives greatly increase their risk of coronary heart disease and ischemic stroke as compared to nonsmoking women who use occasionally oral contraceptives. Nicotine addiction disturbs the normal periodicity of the menstrual cycle and induces early onset of menopause in women; however, the mechanism of the synergistic effects of nicotine and sex hormones on cerebrovascular health is not clearly understood. In the current study based on a rat model of global cerebral ischemia, our goals are (1) to determine whether chronic nicotine exposure abrogates beneficial effects of estrogen on hippocampal neurons subjected to ischemia, and (2) to determine whether nicotine exposure antagonizes estrogen signaling by reducing the availability of estrogen receptor(s). To test the effects of chronic nicotine exposure, normally cycling or ovariectomized rats were injected with nicotine daily for 15 days. To investigate the efficacy of estrogen treatment, nicotine-exposed ovariectomized rats were injected with a bolus of 17β-estradiol and 48 h later ischemia was induced. Our results demonstrated that chronic nicotine exposure followed by ischemic insult at the proestrus stage of the estrous cycle showed that only 14% of normal neurons remained compared to the non-nicotine-treated group (p < 0.05). Similarly, a bolus of 17β-estradiol to nicotine-treated ovariectomized rats showed only 26% of normal neurons remaining as against 47% in the non-nicotine-treated group. Nicotine exposure decreased ERβ but not ERα protein levels in the hippocampus, suggesting a role for ERβ in increased post-ischemic neurodegeneration from nicotine exposure.     

1α,25-Dihydroxyvitamin D3 treatment does not alter neuronal cyclooxygenase-2 expression in the cerebral cortex after stroke

The inducible prostaglandin synthase, cyclooxygenase-2, is upregulated in response to cerebral ischemia and contributes to potentiation of oxidative injury. Cyclooxygenase-2 expression is regulated by retinoic acid receptors, which form heterodimers with vitamin D receptors and vitamin D. In addition, vitamin D has been reported to have neuroprotective qualities. The aim of this study was to examine whether the biologically active vitamin D₃-metabolite 1α,25-dihydroxyvitamin D₃ (1,25-D₃), influences the expression of inducible cyclooxygenase-2 in photothrombotically lesioned brain or is part of an independent neuroprotective mechanism. We compared groups of nonlesioned control rats and infarcted animals, which were treated with either 1,25-D₃ or solvent at different times postlesion. In control animals, cyclooxygenase-2 immunoreactivity was readily evident in almost all cortical neurons of layers II/III as well as in a few pyramidal cells in layer V. Following photothrombotic infarction of the right cortical hindlimb area, there was a significant, but transient, increase in cyclooxygenase-2 labeling which was restricted to neurons of the injured hemisphere in both 1,25-D₃-treated and solvent-treated rats. Highest levels of cyclooxygenase-2 immunoreactivity were seen at 12 and 24 h postlesion, followed by a gradual decrease at later time points. However, no significant differences were detected between 1,25-D₃-treated and solvent-treated lesioned rats, indicating that postischemic neuronal cyclooxygenase-2 upregulation is not influenced by 1,25-D₃. It is concluded that the neuroprotective effect of 1,25-D₃ does not depend on modulations of neuronal COX-2 expression caused by postlesional hyperexcitation.     

Partial hexokinase II knockout results in acute ischemia–reperfusion damage in skeletal muscle of male, but not female, mice

Cellular studies have demonstrated a protective role of mitochondrial hexokinase against oxidative insults. It is unknown whether HK protective effects translate to the in vivo condition. In the present study, we hypothesize that HK affects acute ischemia–reperfusion injury in skeletal muscle of the intact animal. Male and female heterozygote knockout HKII (HK^+/-), heterozygote overexpressed HKII (HK^tg), and their wild-type (WT) C57Bl/6 littermates mice were examined. In anesthetized animals, the left gastrocnemius medialis (GM) muscle was connected to a force transducer and continuously stimulated (1-Hz twitches) during 60 min ischemia and 90 min reperfusion. Cell survival (%LDH) was defined by the amount of cytosolic lactate dehydrogenase (LDH) activity still present in the reperfused GM relative to the contralateral (non-ischemic) GM. Mitochondrial HK activity was 72.6?±?7.5, 15.7?±?1.7, and 8.8?±?0.9 mU/mg protein in male mice, and 72.7?±?3.7, 11.2?±?1.4, and 5.9?±?1.1 mU/mg in female mice for HK^tg, WT, and HK^+/-, respectively. Tetanic force recovery amounted to 33?±?7% for male and 17?±?4% for female mice and was similar for HK^tg, WT, and HK^+/-. However, cell survival was decreased (p?=?0.014) in male HK^+/- (82?±?4%LDH) as compared with WT (98?±?5%LDH) and HK^tg (97?±?4%LDH). No effects of HKII on cell survival was observed in female mice (92?±?2% LDH). In conclusion, in this mild model of acute in vivo ischemia–reperfusion injury, a partial knockout of HKII was associated with increased cell death in male mice. The data suggest for the first time that HKII mediates skeletal muscle ischemia–reperfusion injury in the intact male animal.     

Do hospitalist physicians improve the quality of inpatient care delivery? A systematic review of process, efficiency and outcome measures

Background

Despite more than a decade of research on hospitalists and their performance, disagreement still exists regarding whether and how hospital-based physicians improve the quality of inpatient care delivery. This systematic review summarizes the findings from 65 comparative evaluations to determine whether hospitalists provide a higher quality of inpatient care relative to traditional inpatient physicians who maintain hospital privileges with concurrent outpatient practices.

Methods

Articles on hospitalist performance published between January 1996 and December 2010 were identified through MEDLINE, Embase, Science Citation Index, CINAHL, NHS Economic Evaluation Database and a hand-search of reference lists, key journals and editorials. Comparative evaluations presenting original, quantitative data on processes, efficiency or clinical outcome measures of care between hospitalists, community-based physicians and traditional academic attending physicians were included (n = 65). After proposing a conceptual framework for evaluating inpatient physician performance, major findings on quality are summarized according to their percentage change, direction and statistical significance.

Results

The majority of reviewed articles demonstrated that hospitalists are efficient providers of inpatient care on the basis of reductions in their patients' average length of stay (69%) and total hospital costs (70%); however, the clinical quality of hospitalist care appears to be comparable to that provided by their colleagues. The methodological quality of hospitalist evaluations remains a concern and has not improved over time. Persistent issues include insufficient reporting of source or sample populations (n = 30), patients lost to follow-up (n = 42) and estimates of effect or random variability (n = 35); inappropriate use of statistical tests (n = 55); and failure to adjust for established confounders (n = 37).

Conclusions

Future research should include an expanded focus on the specific structures of care that differentiate hospitalists from other inpatient physician groups as well as the development of better conceptual and statistical models that identify and measure underlying mechanisms driving provider-outcome associations in quality.     

Circulating concentrations, cerebral output of the CINC-1 and blood–brain barrier disruption in Wistar rats after pneumococcal meningitis induction

Pneumococcal meningitis is a severe infectious illness of the central nervous system (CNS), with high rates of lethality and morbidity, being that the microorganism and the host's inflammatory response are responsible for cerebral complications. Moreover, the blood–brain barrier (BBB) itself secretes cytokines and, because of the bipolar nature of the BBB, these substances can be secreted into either the CNS compartment or in the blood, so patients with acute bacterial meningitis frequently develop sepsis. Therefore, the aim of this study was to evaluate the cytokine/chemokine levels in different vessels and the BBB integrity after pneumococcal meningitis induction. Wistar rats were infected with Streptococcus pneumoniae, and the BBB integrity was investigated using Evan's blue dye. Also, blood from the carotid artery and jugular vein was collected in order to perform tumour necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-60 and cytokine-induced neutrophil chemoattractant-1 (CINC-1) analyses by enzyme-linked immunosorbent assay (ELISA). CINC-1 levels were increased at 6 h in the arterial plasma and at 3 and 6 h in the jugular plasma. We observed BBB breakdown between 12 and 24 h in the hippocampus and at 12 and 18 h in the cortex after pneumococcal meningitis induction. The increase of CINC-1 occurred prior to the BBB breakdown. CINC-1 is a neutrophil chemoattractant and it may be related to early events in the pneumococcal meningitis pathophysiology.     

Antiinflammatory action of thielocin A1β, a group II phospholipase A2 specific inhibitor,in rat carrageenan-induced pleurisy

Extracellular phospholipase A₂ (PLA₂) activity was detected in exudate from rat carrageenan-induced pleurisy using [³H]oleic acid-labeledEscherichia coli as substrate. Both exudate volume and PLA₂ activity increased up to 24 h after carrageenin injection. Specific absorption of this activity by anti-group II PLA₂ (PLA₂-II) antibody indicated that the PLA₂ activity in the pleural exudate was PLA₂-II. Thielocin Al, a novel type of PLA₂ inhibitor from fungi, inhibited this PLA₂-II activity in a dose-dependent manner (IC₅₀=0.32M). Thielocin A1 correspondingly reduced both exudate volume and PLA₂-II activity in the exudate in a dose-dependent manner when coinjected with carrageenan. The exudate volume was also significantly decreased when indomethacin, a cyclooxygenase inhibitor, or dexamethasone, a steroidal antiinflammatory drug, was coinjected with carrageenan. However, neither indomethacin nor dexamethasone could significantly attenuate the PLA₂-II activity in exudate In addition, indomethacin and dexamethasone significantly reduced the levels of PGE₂ in the exudate. However, thielocin A1 had no effect on the PGE₂ content in the exudate. These results suggest that thielocin A1 shows antiinflammatory activity due to inhibition of PLA₂-II and offer evidence for the significance of PLA₂1I in the propagation of inflammatory processes.     

Chronic intracerebroventricular exposure to β-amyloid(1–40) impairs object recognition but does not affect spontaneous locomotor activity or sensorimotor gating in the rat

This study examined the cognitive effects of chronic in vivo exposure to beta-amyloid(1-40) via the intracerebroventricular route on two distinct paradigms. The first test evaluated a form of early attentional control referred to as sensorimotor gating in which an antecedent weak prepulse stimulus modulates the reactivity to a subsequent startle-eliciting stimulus. The second test utilized the spontaneous preference for a novel object over that of a familiar one in rats as a measure of object recognition memory. We found that beta-amyloid exposure leads to a severe deficit in the object memory test but spares sensorimotor gating. Moreover, unlike the water maze deficit induced by beta-amyloid (Nag et al., in preparation), the deficit on object recognition was resistant to amelioration by systemic physostigmine treatment at a dose of 0.06 mg/kg per day intraperitoneally. The present results add to previous reports that beta-amyloid exposure can lead to deficits on hippocampal lesion sensitive tasks, suggesting that dysfunction of the rhinal cortices in addition to that of the septohippocampal system is implicated in beta-amyloid-induced behavioral impairments. It therefore lends support to the hypothesis that beta-amyloid exposure can lead to severe impairment across multiple memory systems.     

Electrical stimulation of cerebellar fastigial nucleus promotes the expression of growth arrest and DNA damage inducible gene β and motor function recovery in cerebral ischemia/reperfusion rats

This study focused on the effects of electrical stimulation of cerebellar fastigial nucleus on the expression of growth arrest and DNA damage inducible gene β (Gadd45β) and on motor function recovery after focal cerebral ischemia/reperfusion (I/R) in rats. Sprague-Dawley (SD) rats were randomly divided into 4 groups: sham I/R (control group), I/R (I/R group), I/R with sham stimulation and I/R with electrical stimulation at 6h, 12h, 24h, 2d and 3d after I/R. Cerebral ischemia and reperfusion was established by nylon monofilament occlusion method. Fastigial nucleus (FN) electrical stimulation was applied at 2h after ischemia for 1h. The changes in the expression of Gadd45β were analyzed by immunohistochemistry, real-time polymerase chain reaction (PCR) and Western-blot respectively. Another group of rats were divided into the same 4 groups. Montoya staircase test score was used to test the motor function of affected forelimb. The levels of Gadd45β were significantly elevated after I/R injury. FN electrical stimulation treatment elevated the expression of Gadd45β further and improved motor function recovery. These results suggest that FN electrical stimulation can promote the expression of Gadd45β and motor function recovery after focal cerebral ischemia.     

Manual stimulation of the whisker pad after hypoglossal–facial anastomosis (HFA) using a Y-tube conduit does not improve recovery of whisking function

Facial nerve injury is a common clinical trauma involving long-term functional deficits with facial asymmetry leading to associated psychological issues and social hardship. We have recently shown that repair by hypoglossal–facial or facial–facial nerve surgical end-to-end anastomosis and suture [hypoglossal–facial anastomosis (HFA) or facial–facial anastomosis (FFA)] results in collateral axonal branching, polyinnervation of neuromuscular junctions (NMJs) and poor function. We have also shown that another HFA repair procedure using an isogenic Y-tube (HFA + Y-tube) and involving a 10-mm gap reduces collateral axonal branching, but fails to reduce polyinnervation. Furthermore, we have previously demonstrated that manual stimulation (MS) of facial muscles after FFA or HFA reduces polyinnervation of NMJs and improves functional recovery. Here, we examined whether HFA + Y-tube and MS of the vibrissal muscles reduce polyinnervation and restore function. Isogenic Y-tubes were created using abdominal aortas. The proximal hypoglossal nerve was inserted into the long arm and sutured to its wall. The distal zygomatic and buccal facial nerve branches were inserted into the two short arms and likewise sutured to their walls. Manual stimulation involved gentle stroking of the vibrissal muscles by hand mimicking normal whisker movement. We evaluated vibrissal motor performance using video-based motion analysis, degree of collateral axonal branching using double retrograde labeling and the quality of NMJ reinnervation in target musculature using immunohistochemistry. MS after HFA + Y-tube reduced neither collateral branching, nor NMJ polyinnervation. Accordingly, it did not improve recovery of function. We conclude that application of MS after hypoglossal–facial nerve repair using an isogenic Y-tube is contraindicated: it does not lead to functional recovery but, rather, worsens it.     

A paternal deletion of MKRN3, MAGEL2 and NDN does not result in Prader�CWilli syndrome

The Prader–Willi syndrome (PWS) is caused by a 5–6 Mbp de novo deletion on the paternal chromosome 15, maternal uniparental disomy 15 or an imprinting defect. All three lesions lead to the lack of expression of imprinted genes that are active on the paternal chromosome only: MKRN3, MAGEL2, NDN, C15orf2, SNURF-SNRPN and more than 70 C/D box snoRNA genes (SNORDs). The contribution to PWS of any of these genes is unknown, because no single gene mutation has been described so far. We report on two patients with PWS who have an atypical deletion on the paternal chromosome that does not include MKRN3, MAGEL2 and NDN. In one of these patients, NDN has a normal DNA methylation pattern and is expressed. In another patient, the paternal alleles of these genes are deleted as the result of an unbalanced translocation 45,X,der(X)t(X;15)(q28;q11.2). This patient is obese and mentally retarded, but does not have PWS. We conclude that a deficiency of MKRN3, MAGEL2 and NDN is not sufficient to cause PWS.     

Use of blood urea nitrogen, creatinine, interleukin-6, granulocyte–macrophage colony stimulating factor in combination to predict the severity and outcome of abdominal sepsis in rats

Objectives

Accurate and timely diagnosis and prognosis of sepsis remain challenging. A combination of markers, as opposed to single ones, may improve the prognosis, and therefore survival. This study compared the effectiveness of routinely used biomarkers of sepsis alone and in combination for the prediction of outcome in rats with abdominal sepsis.

Methods

Rats were subjected to sepsis induced by cecal ligation and puncture (CLP). Seventeen biomarkers were detected 12?h after the CLP. Correlation between the biomarkers and outcome of rats was analyzed; the correlated biomarkers were analyzed by logistic regression analysis and the area under the receiver operating characteristic (ROC) curve was computed to compare their performance in the prognosis of sepsis.

Results

A total of 49 rats were eligible for analysis. Body temperature (T), blood urea nitrogen (BUN), creatinine (Cr), alanine aminotransferase (ALT), creatine kinase (CK), interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) levels after the CLP were negatively correlated with the survival outcome, while platelet count (PLT), high-mobility group box protein 1 (HMGB1) and granulocyte–macrophage colony stimulating factor (GM-CCF) were positively correlated with the survival outcome (P?P?Conclusion A combination of different biomarkers improves the diagnostic accuracy and is more effective in the prognosis of sepsis in rats. Use of BUN, Cr, IL-6, GM-CSF in combination to predict the severity and outcome in rats with abdominal sepsis exhibited acceptable diagnostic characteristics.     

Augmented prostaglandin E2 generation resulting from increased activities of cytosolic and secretory phospholipase A2 and induction of cyclooxygenase-2 in interleukin-1β-stimulated rat calvarial cells during the mineralizing phase

OBJECTIVE AND DESIGN: To assess prostaglandin (PG) E2 production by osteoblasts during the mineralizing phase after interleukin (IL)-1beta stimulation, using an in vitro system of rat calvarial cells cultured for 21 days. METHODS: The cells, which reached confluence after 3 days, were designated day 0 cells. Culture was continued for a further 21 days after confluence. The cells on the 21st day of the culture were designated day 21 cells. RESULTS: The PGE2 concentration in the medium of the day 21 cells was increased 72 h after IL-1beta treatment, and reached a peak level approximately 1,400 times that of the day 0 cells 6 h after IL-1beta treatment. We examined the effects of IL-1beta on PGE2 production and changes in the relevant enzyme activities, and found that the activities of cytosolic phospholipase A2 (cPLA2), type II secretory PLA2 (sPLA2) and cyclooxygenase (COX)-2 in the day 21 cells were increased. Both selective COX-2 inhibitor and cPLA2 inhibitor abolished PGE2 generation, whereas an sPLA2 inhibitor partially inhibited it. Taken together, these results indicate that COX-2 and cPLA2 play pivotal roles and sPLA2 is involved in IL-1beta-stimulated PGE2 production by these cells. Furthermore, we found that IL-Ibeta treatment induced PGE synthase activity and this correlated well with PGE2 production. CONCLUSION: Augmented PGE2 production by mineralizing osteoblasts after IL-1beta treatment, and the involvement of IL-1beta-induced cPLA2, sPLA2, COX-2 and PGE synthase activities in this phenomenon were demonstrated.     

A monoclonal antibody that recognizes Epstein-Barr virus nuclear antigen 2 (EBNA 2) amino acids 1–58 does not react with EBNA 2 in native form,consistent with the self-association of EBNA 2 through the amino-terminus

Summary. We have generated a mouse IgG₁ monoclonal antibody (mAb) that recognizes amino acids 1–58 of Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA 2) of type 1 EBV strain B95-8. mAb Y101 also reacted with EBNA 2 of EBV type 2 strains MISP and Jijoye in immunoblots, whereas Jijoye EBNA 2 was not detected by the widely used mAb PE2. mAb Y101, in contrast to mAb PE2, reacted with faster migrated, hypophosphorylated proteins of type 1 EBNA 2 as intensely as slower migrated, hyperphosphorylated ones. mAb Y101 did not react in fixed-cell immunostaining or cell extract immunoprecipitation. The results implicate that the amino-terminal epitope is not exposed in a native form, consistent with the previously reported idea of self-association of EBNA 2 through the amino-terminus. mAb Y101 is the first mAb to the EBNA 2 amino-terminus and will be useful for further analyses of the structure and function of EBNA 2.     

A cyclic pathway of P2 × 7, bradykinin,and dopamine receptor activation induces a sustained articular hyperalgesia in the knee joint of rats

Objective

We investigated whether: (1) P2?×?7 receptor activation by its agonist (BzATP) induces articular hyperalgesia in the rat’s knee joint via inflammatory mechanisms and (2) activation of P2?×?7 receptors by endogenous ATP contributes to the articular hyperalgesia induced by bradykinin, TNF-α, IL-1β, CINC-1, PGE_2, and dopamine.

Methods

The articular hyperalgesia was quantified using the rat knee joint incapacitation test. The knee joint inflammation, characterized by the concentration of pro-inflammatory cytokines and by neutrophil migration, was quantified in the synovial lavage fluid by ELISA and myeloperoxidase enzyme activity assay, respectively.

Results

BzATP induced a dose-dependent articular hyperalgesia in the rat’s knee joint that was significantly reduced by the selective antagonists for P2?×?7, bradykinin B₁ or B₂ receptors, β₁ or β₂ adrenoceptors, and by pre-treatment with Indomethacin. BzATP induced a local increase of TNF-α, IL-1β, IL-6, and CINC-1 concentration and neutrophil migration into the knee joint. The co-administration of the selective P2?×?7 receptor antagonist A-740003 significantly reduced the articular hyperalgesia induced by bradykinin and dopamine, but not by TNF-α, IL-1β, CINC-1, and PGE₂.

Conclusions

P2?×?7 receptor activation induces articular hyperalgesia mediated by the previous inflammatory mediator release. P2?×?7 receptor-induced articular hyperalgesia is sustained by the involvement of this purinergic receptor in bradykinin and dopamine-induced hyperalgesia in the knee joint.

     

LY404187, a potentiator of AMPARs,enhances both the amplitude and 1/CV of AMPA EPSCs but not NMDA EPSCs at CA3–CA1 synapses in the hippocampus of neonatal rats

Cyclothiazide is a well-known AMPAR potentiator, but it has also been shown to enhance the probability of presynaptic release in some cases. Interestingly, cyclothiazide has been shown to reveal AMPA EPSCs at silent CA3–CA1 synapses (which exhibit NMDA EPSCs but not AMPA EPSCs) in the hippocampus of neonatal or developing rats 0025 and 0045, but this particular result has not been reproduced at other types of synapses 0060 and 0070. Although this discrepancy may be due to the different mechanisms underlying silent synapses in distinct brain subregions, it is also possible that cyclothiazide has pre- and postsynaptic molecular targets that are differentially expressed at the different types (or different developing stages) of synapses. In this study, we reexamined, using a new AMPAR potentiator, LY404187, whether AMPAR potentiation leads to the conversion of silent CA3–CA1 synapses into functional synapses (exhibiting both AMPA and NMDA EPSCs) in the hippocampus of neonatal rats. LY404187 did not appear to alter the probability of presynaptic release, as evidenced by the lack of significant changes in both the amplitude and the paired-pulse facilitation ratio (an index of release probability) of NMDA EPSCs. LY404187 enhanced both the amplitude and 1/CV² (CV: coefficient of variation) of AMPA EPSCs but not NMDA EPSCs. Because an increase in 1/CV² reflects an increased number of functional synapses and/or an enhanced release probability, the LY404187-induced increase in the 1/CV² value of AMPA EPSCs, but not NMDA EPSCs, likely indicates an increased number of synapses exhibiting AMPA EPSCs but not an increased number of synapses exhibiting NMDA EPSCs. Because AMPARs and NMDARs are co-localized at the same synapses, our findings are consistent with a scenario in which LY404187 enables silent synapses to acquire AMPA EPSCs.     

A pilot study on reparixin,a CXCR1/2 antagonist,to assess safety and efficacy in attenuating ischaemia–reperfusion injury and inflammation after on-pump coronary artery bypass graft surgery

Reparixin, a CXCR 1/2 antagonist, has been shown to mitigate ischaemia–reperfusion injury (IRI) in various organ systems in animals, but data in humans are scarce. The aim of this double-blinded, placebo-controlled pilot study was to evaluate the safety and efficacy of reparixin to suppress IRI and inflammation in patients undergoing on-pump coronary artery bypass grafting (CABG). Patients received either reparixin or placebo (n = 16 in each group) after induction of anaesthesia until 8 h after cardiopulmonary bypass (CPB). We compared markers of systemic and pulmonary inflammation, surrogates of myocardial IRI and clinical outcomes using Mann–Whitney U- and Fisher''s exact tests. Thirty- and 90-day mortality was 0% in both groups. No side effects were observed in the treatment group. Surgical revision, pleural and pericardial effusion, infection and atrial fibrillation rates were not different between groups. Reparixin significantly reduced the proportion of neutrophil granulocytes in blood at the beginning [49%, interquartile range (IQR) = 45–57 versus 58%, IQR = 53–66, P = 0·035], end (71%, IQR = 67–76 versus 79%, IQR = 71–83, P = 0·023) and 1 h after CPB (73%, IQR = 71–75 versus 77%, IQR = 72–80, P = 0·035). Reparixin patients required a lesser positive fluid balance during surgery (2575 ml, IQR = 2027–3080 versus 3200 ml, IQR = 2928–3778, P = 0·029) and during ICU stay (2603 ml, IQR = 1023–4288 versus 4200 ml, IQR = 2313–8160, P = 0·021). Numerically, more control patients required noradrenaline ≥ 0·11 μg/kg/min (50 versus 19%, P = 0·063) and dobutamine (50 versus 25%, P = 0·14). Therefore, administration of reparixin in CABG patients appears to be feasible and safe. It concurrently attenuated postoperative granulocytosis in peripheral blood.     

That which does not kill us makes us stronger – Does Nietzsche’s quote apply to islets? A re-evaluation of the passenger leukocyte theory,free radicals,and glucose toxicity in islet cell transplantation

In clinical islet transplantation, isolated islets are embolized into the liver via the portal vein (PV); however, up to 70% of the islets are lost in the first few days after transplantation (i.e., too quickly to be mediated by the adaptive immune system). Part of early loss is due to instant blood-mediated inflammatory reaction, an immune/thrombotic process caused by islets interacting with complement. We have shown that glucose toxicity (GT) also plays a critical role based upon the observation that islets embolized into the PVs of diabetic athymic mice are rapidly lost but, if recipients are not diabetic, the islet grafts persist. Using donor islets resistant to the β-cell toxin streptozotocin, we have shown that intraportal islets engrafted in non-diabetic athymic mice for as little as 3 days will maintain normoglycemia when streptozotocin is administered destroying the recipient’s native pancreas β-cells. What is the mechanism of GT in β-cells? Chronic exposure to hyperglycemia over-exerts β-cells and their electron transport chains leak superoxide radicals during aerobic metabolism. Here we reinterpret old data and present some compelling new data supporting a new model of early intraportal islet graft loss. We hypothesize that diabetes stimulates overproduction of superoxide in both the β-cells of the islet grafts and the endothelial cells lining the intraportal microvasculature adjacent to where the embolized islets become lodged. This double dose of oxidant damage stresses both the islets, which are highly susceptible to free radicals because of inherent low levels of scavenging enzymes, and the adjacent hepatic endothelial cells. This, superimposed upon localized endothelial damage caused by embolization, precipitates inflammation and coagulation which further damages islet grafts. Based upon this model, we predict that pre-exposing islets to sub-lethal hyperoxia should up-regulate islet free radical scavenging enzyme levels and promote initial engraftment; reinterpretation of 30 years old “passenger leukocyte” data and preliminary new data support this. Other data suggests that pre-exposure of recipients to hyperoxia could up-regulate antioxidant enzymes in the hepatic endothelium. The combination of both effects could markedly enhance early intraportal islet graft survival and engraftment. Finally, if our model is correct, current in vitro and in vivo tests used to test batches of harvested islets for viability and function prior to transplantation are poorly conceived (n.b., it is already well-known that results using these tests often do not predict clinical islet transplantation success) and a different testing paradigm is suggested.