Reduction of cerebral infarct volume by apocynin requires pretreatment and is absent in Nox2-deficient mice

Background and purpose:

Reactive oxygen species (ROS) derived from Nox2-containing reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity is reportedly detrimental in cerebrovascular disease. However, ROS generation by other Nox isoforms may have a physiological role. No Nox2-selective inhibitors have yet been identified, and thus it is unclear whether isoform non-selective Nox inhibitors would necessarily improve outcome after stroke. We assessed the effect of apocynin on cerebrovascular ROS production and also on outcome following cerebral ischaemia when administered either before ischaemia or after cerebral reperfusion. The involvement of Nox2-containing NADPH oxidase in the effects of apocynin was assessed using Nox2^−/− mice.

Experimental approach:

Transient cerebral ischaemia was induced by 0.5 h middle cerebral artery occlusion followed by 23.5 h reperfusion. Mice received apocynin (2.5 mg·kg⁻¹, i.p.) either 0.5 h before ischaemia or 1 h after reperfusion. In situ superoxide production after cerebral ischaemia-reperfusion was measured in brain sections of wild-type mice at 24 h using dihydroethidium fluorescence.

Key results:

Treatment with apocynin 0.5 h before ischaemia reduced total infarct volume, neurological impairment and mortality in wild-type but not Nox2^−/− mice. Conversely, treatment with apocynin 1 h after initiation of reperfusion had no protective effect. Cerebral ischaemia and reperfusion increased superoxide production in the brain at 24 h, and pretreatment but not posttreatment with apocynin reduced superoxide levels.

Conclusions and implications:

Apocynin improves outcome following stroke when administered before ischaemia in wild-type but not Nox2^−/− mice.     

In a review of stroke rehabilitation studies,concealed allocation was under reported

ObjectiveThe objective of this two-phase study was to assess the adequacy of the reporting of concealed allocation (CA) in randomized controlled trials (RCTs) evaluating interventions associated with stroke rehabilitation.Study Design and SettingIn phase I of the study, 50 RCTs included in a systematic review were selected to establish agreement between two raters. Two investigators determined if the method described to conceal the randomization schedule was adequate, inadequate, or not reported. In phase II, using a larger sample size (n = 165), the differences in the proportion of studies with and without adequate CA are reported for two comparisons: (1) pharmacological vs. nonpharmacological trials and (2) multicentered vs. single-site studies.ResultsIn both phases I and II, CA was described adequately in one-third of all studies sampled. The agreement between raters was 88% (к = 0.79; 95% confidence interval: 0.65, 0.94). No significant differences in the adequacy of reporting for CA were found with respect to study type (pharmacological vs. nonpharmacological), whereas multicentered trials reported adequacy of CA more frequently.ConclusionAlthough concealment of group allocation is an important feature of trial design, it was frequently not reported in many RCTs associated with stroke rehabilitation.     

Alveolar bone and the bisphosphonates

Bisphosphonate associated osteonecrosis of the jaws (ONJ) usually commences at the alveolus. Comparison is made between the structure and function of long bones and alveolar bone and the differing susceptibilities of the bisphosphonates at these different sites are explored. Current concepts of the causation of ONJ are discussed. The clinical implications of these findings to dentists managing periodontal conditions are presented.     

Protective effect of allopurinol in the renal ischemia--reperfusion in uninephrectomized rats

The effect of allopurinol (an inhibitor of xanthine oxidase) on oxidative stress, renal dysfunction, and histologic alterations was evaluated during the renal ischemia--reperfusion in uninephrectomized rats. Renal malondialdehyde and serum creatinine levels significantly increased after renal ischemia--reperfusion. However, the pretreatment with allopurinol demonstrated a protector effect in these parameters. Renal ischemia--reperfusion provoked a significant renal damage in the operated group. Tubular atrophy and interstitial fibrosis were attenuated by allopurinol when given prior to the surgery. In our study, allopurinol had a strong tendency to exert a beneficial effect during renal ischemia--reperfusion in uninephrectomized rats.     

Halothane induces oxidative stress and NF-kappaB activation in rat liver: protective effect of propofol

We investigated the effects of propofol on markers of oxidative stress, nuclear factor kappa B (NF-kappaB) activation and inducible nitric oxide synthase (iNOS) expression in liver of rats treated with halothane under hypoxic conditions. Male Wistar rats received halothane 1%/oxygen 14%, oxygen 14%/propofol 60 mg kg(-1) i.p., or halothane 1%/oxygen 14%/propofol 60 mg kg(-1) i.p. Morphological examination showed complete loss of architecture with massive necrosis of parenchyma in the halothane group, while only minor histological abnormalities were observed in rats receiving halothane plus propofol. The cytosolic concentration of TBARS and the hydroperoxide-initiated chemiluminescence increased significantly in the liver of animals from the halothane group (+62% and +40% versus controls, respectively), and this increase was abolished by propofol administration. Halothane induced a marked activation of NF-kappaB (+180%), and resulted in a significant decrease of the nonphosphorylated form of the inhibitor IkappaBalpha (-53%), while phosphorylated IkappaBalpha protein level was markedly increased (+146%). Propofol administration lowered these effects to +30% (NF-kappaB), -26% (nonphosphorylated IkappaBalpha), and +56% (phosphorylated IkappaBalpha). The increase of iNOS protein level (+59%) induced by halothane was significantly reduced to +22% by additional administration of propofol. Results obtained show that administration of propofol inhibits oxidative stress, NF-kappaB nuclear traslocation and iNOS overexpression in liver of rats receiving halothane. Propofol treatment, by inhibiting the NF-kappaB signal transduction pathway, might block the production of noxious mediators involved in the development of halothane-induced injury.     

Rat ferritin-H: cDNA cloning, differential expression and localization during hepatocarcinogenesis

Elevated serum ferritin levels, especially of the H subunit, accompany many clinical malignancies. By using the subtraction-enhanced display technique, we have recently isolated several cDNA clones which are over- expressed in rat hepatocellular carcinoma induced by diethylnitrosamine. One 830-base-pair clone was 88% similar to human ferritin-H cDNA and encoded a 182 amino acid protein which is 97% homologous to human ferritin-H chain. Hepatic mRNA levels of ferritin-H were increased markedly at the early stage of diethylnitrosamine- induced hepatocarcinogenesis in the rat (6 weeks) and appeared more than 10-fold overexpressed as the tumour progressed. In contrast, hepatic ferritin-H mRNA remained constant during liver regeneration after a 70% partial hepatectomy. In situ hybridization showed that over- expression of ferritin-H was exclusively localized to preneoplastic foci, to tumour nodules and to tumour cells invading blood vessels. These findings suggest that ferritin-H is a highly conserved protein, its over-expression during tumour development is phenotypically correlated with tumour initiation and/or progression, and it is useful as an early marker for hepatocellular carcinoma.      

Genomic screening for beta-sarcoglycan gene mutations: missense mutations may cause severe limb-girdle muscular dystrophy type 2E (LGMD 2E)

Autosomal recessive limb-girdle muscular dystrophies (LGMDs) are genetically heterogeneous. A subgroup of these disorders is caused by mutations in the dystrophin-associated sarcoglycan complex. Truncating mutations in the 43 kDa beta-sarcoglycan gene (LGMD 2E) were originally identified in a sporadic case of Duchenne-like muscular dystrophy, and a common missense mutation (T151R) was identified independently in Indiana Amish pedigrees with a milder form of LGMD. To facilitate mutational analysis of larger numbers of patients directly from genomic DNA, as opposed to reverse transcribed RNA from muscle biopsies, we have determined the genomic structure of the beta-sarcoglycan gene. The open reading frame of the beta-sarcoglycan coding region extends over six exons. Primers were designed for PCR amplification of single exons from genomic DNA and subsequent single strand conformation polymorphism (SSCP) analysis. We screened 15 patients from the Brazilian LGMD patient population, 13 of whom followed a severe course. Most of the patients had been assessed previously for deficiency of alpha- sarcoglycan immunofluorescence on muscle biopsy sections as a marker for disease of the sarcoglycan complex. Novel mutations in two familial and two sporadic cases of severe childhood-onset LGMD were identified. Only one of these patients carried a truncating mutation (homozygous 2 bp deletion, FS164TER), while the other three carried missense mutations (homozygous R91P, homozygous M100K, heterozygous recessive L108R; only one allele could be identified in this family). All three missense mutations occurred in exon 3, coding for the immediate extracellular domain. Complete absence for all three of the known sarcoglycans was noted by immunohistochemistry on muscle biopsy sections of the patients.