Hydrogen peroxide inhibits gap junctional intercellular communication in glutathione sufficient but not glutathione deficient cells

Cell to cell communication via gap junctions is essential in the maintenance of the homeostatic balance of multicellular organisms. Aberrant intercellular gap junctional communication (GJIC) has been implicated in tumor promotion, neuropathy and teratogenesis. Oxidative stress has also been implicated in similar pathologies such as cancer. We report a potential link between oxidative stress and GJIC. Hydrogen peroxide, a known tumor promoter, inhibited GJIC in WB-F344 rat liver epithelial cells with an I50 value of 200 microM. Inhibition of GJIC by H2O2 was reversible as indicated by the complete recovery of GJIC with the removal of H2O2 via a change of fresh media. Free radical scavengers, such as t-butyl alcohol, propylgallate, and Trolox, did not prevent the inhibition of GJIC by H2O2, which indicated that the effects of H2O2 on GJIC was probably not a consequence of aqueous free radical damage. The depletion of intracellular GSH reversed the inhibitory effect of H2O2 on GJIC. The treatment of glutathione- sufficient cells with H2O2 resulted in the hyperphosphorylation of connexin43, which is the basic subunit of the hexameric gap junction protein, as determined by Western blot analysis. TPA, a well-known tumor promoter, also inhibits GJIC via hyperphosphorylation of GJIC, which is a result of protein kinase-C activation. However, H2O2 also induced hyperphosphorylation in GSH-deficient cells that had normal rates of GJIC. Therefore, the mechanism of GJIC inhibition must be different from the TPA-pathway and involves GSH.      

A crucial role for TNF-α in mediating neutrophil influx induced by endogenously generated or exogenous chemokines,KC/CXCL1 and LIX/CXCL5

Background and purpose:

Chemokines orchestrate neutrophil recruitment to inflammatory foci. In the present study, we evaluated the participation of three chemokines, KC/CXCL1, MIP-2/CXCL2 and LIX/CXCL5, which are ligands for chemokine receptor 2 (CXCR2), in mediating neutrophil recruitment in immune inflammation induced by antigen in immunized mice.

Experimental approach:

Neutrophil recruitment was assessed in immunized mice challenged with methylated bovine serum albumin, KC/CXCL1, LIX/CXCL5 or tumour necrosis factor (TNF)-α. Cytokine and chemokine levels were determined in peritoneal exudates and in supernatants of macrophages and mast cells by elisa. CXCR2 and intercellular adhesion molecule 1 (ICAM-1) expression was determined using immunohistochemistry and confocal microscopy.

Key results:

Antigen challenge induced dose- and time-dependent neutrophil recruitment and production of KC/CXCL1, LIX/CXCL5 and TNF-α, but not MIP-2/CXCL2, in peritoneal exudates. Neutrophil recruitment was inhibited by treatment with reparixin (CXCR1/2 antagonist), anti-KC/CXCL1, anti-LIX/CXCL5 or anti-TNF-α antibodies and in tumour necrosis factor receptor 1-deficient mice. Intraperitoneal injection of KC/CXCL1 and LIX/CXCL5 induced dose- and time-dependent neutrophil recruitment and TNF-α production, which were inhibited by reparixin or anti-TNF-α treatment. Macrophages and mast cells expressed CXCR2 receptors. Increased macrophage numbers enhanced, while cromolyn sodium (mast cell stabilizer) diminished, LIX/CXCL5-induced neutrophil recruitment. Macrophages and mast cells from immunized mice produced TNF-α upon LIX/CXCL5 stimulation. Methylated bovine serum albumin induced expression of ICAM-1 on mesenteric vascular endothelium, which was inhibited by anti-TNF-α or anti-LIX/CXCL5.

Conclusion and implications:

Following antigen challenge, CXCR2 ligands are produced and act on macrophages and mast cells triggering the production of TNF-α, which synergistically contribute to neutrophil recruitment through induction of the expression of ICAM-1.     

N-(1-乙氧羰基-3-苯氨甲酰基丙基)甘氨酰甘氨酸衍生物的合成

报道4个N-(1-[1-乙氧羰基-3-(对甲)苯氨甲酰基]丙基甘氨酰｝-N-取代甘氨酸(XI_1～4)和5个1-[1-乙(或甲)氧羰基-3-(对甲)苯氨甲酰基]丙基-4-取代-1,4-哌嗪-2,5-二酮(XII_1～5)共9个估计有血管紧张素转化酶抑制活性化合物的合成和鉴定。所有这些化合物及9个相应的酯(X_1～9)均未见文献报道。药理初试结果,化合物XII₂,XII₅,XI₄和XII₁均有较强降压活性。     

Quality of life (QOL) assessment of MIP (mitomycin, ifosfamide and cisplatin) chemotherapy in advanced non-small cell lung cancers (NSCLC)

BACKGROUND: Quality of life (QOL) assessment has emerged to measure and quantify the balance between treatment benefit and toxicity, and has a value in predicting response and overall survival in cancer patients. METHODS: From July 1995 to February 1997, 38 symptomatic patients with advanced non-small cell lung cancer (NSCLC) were treated with MIP chemotherapy (mitomycin 6 mg/m2, ifosfamide 3000 mg/m2 and cisplatin 50 mg/m2 on day 1 every 3 weeks). Patients were assessed for QOL including physical well-being, general symptoms and lung cancer-specific symptoms, as well as objective response. RESULTS: The overall response rate was 38.9% (14/36, all were partial response) and the median duration of response was 3.5 months [95% confidence interval (CI) 2.0-4.0]. The median duration of overall survival was 7 months (95% CI 5.9-8.5). The overall improvement of QOL was 58.3% with 21 patients feeling better on treatment. The toxicity of chemotherapy was mild, mainly nausea/vomiting and minimal alopecia. Using multiple clinical predictors of survival (age, histology, stage, performance status), only change of QOL emerged significantly (P = 0.0007). CONCLUSIONS: MIP had an endurable response and low toxicity profile, and provided good QOL. Integral QOL data in our study provided the strong prediction of survival in advanced NSCLC. Further experienced QOL study will provide greatly enhanced outcome data in clinical trials.      

Involvement of TSC genes and differential expression of other members of the mTOR signaling pathway in oral squamous cell carcinoma

Background  

Despite extensive research, the five-year survival rate of oral squamous cell carcinoma (OSCC) patients has not improved. Effective treatment of OSCC requires the identification of molecular targets and signaling pathways to design appropriate therapeutic strategies. Several genes from the mTOR signaling pathway are known to be dysregulated in a wide spectrum of cancers. However, not much is known about the involvement of this pathway in tumorigenesis of OSCC. We therefore investigated the role of the tumor suppressor genes, TSC1 and TSC2, and other members of this pathway in tumorigenesis of OSCC.     

Limited posterior thoracotomy for the correction of intra cardiac anomalies–current perspectives

Background Though the use of median stermotomy has been fairly standardized for the approach to the heart and great vessels, since the advent of cosmetically appealing incisions, thoracotomy has come to be a justifiable alternative incision. This paper presents our experience with this approach and the advantages over the conventional approach as well as over other incisions for the correction of intra-cardiac anomalies. Methods 93 patients underwent open cardiac procedures using the posterior thoracotomy approach since June 1997 to December 2000. There were 69 patients with ostium secundum atrial septal defects and 12 patients with sinus venous defects. Other anomalies included perimembranous ventricular septal defects in 3 patients, partial atrioventricular septal defects in 3 patients and transitional atrioventricular septal defects in 2 patients. Besides these, one patient each underwent atrial septectomy with right modified Blaloc—Taussing shunt and correction of hemianomalous pulmonary venous connection with intact atrial septum using this approach. The median age of the patients was 8 years with a range of 10 months to 41 years. 10 patients were males. Results The median operation time (skin to skin) was 236 minutes. Median bypass times and aortic cross clamp times were 63 minutes and 31.5 minutes respectively. The median ICU stay was 25.2 hours. There were no significant immediate post operative complications requiring intervention in any patient. The mean chest drainage was 80 ml per 24 hours. One patient had a superficial wound dehiscence which healed with daily dressings One patient had atelectasis of the right upper lobe which recovered with chest physiotherapy. All patients are on regular follow up to assess the status of their scars. One patients developed a mass on the right atrial free wall following closure of atrial septal defect one year earlier and the underwent reoperation for removal of the mass. Patients on follow up were interrogated and all were satisfied with the cosmesis of their scars. None of the patients had any physical disability due to their scars. Conclusions The limited posterior thoracotomy incision offers a cosmetically attractive approach to the heart in selected patients. The approach is easy and the techniques reproducible. The technique carries with it no additional risk and has the advantage of not interfering with future development of the breast in young pre pubertal girls.     

Kimura disease of the eyelid in an Indian man

Kimura disease is a rare idiopathic chronic inflammatory disease, characterized by subcutaneous nodular lesions in the head and neck area. Ophthalmic manifestation of Kimura disease involves orbital and eyelid lesions mostly in Asian patients, but it has been described in White patients and Black Caribbean patients. Kimura disease is usually associated with eosinophilia and occasionally with renal disease. Here, we report a case of Kimura disease of the eyelid in a 50-year-old Indian man with eosinophilia. The main differential diagnosis was angiolymphoid hyperplasia with eosinophilia. Histology is crucial to separate these two entities, and our case was shown to be Kimura disease by histology. To our knowledge, this is the first report of a person of Indian origin to develop Kimura disease involving the eyelid.     

Detection of reactive oxygen species (ROS) and apoptosis in human fragmented embryos

In human in-vitro fertilization (IVF)-embryo transfer, the in-vitro culture environment differs from in-vivo conditions in that the oxygen concentration is higher, and in such conditions the mouse embryos show a higher concentration of reactive oxygen species (ROS) in simple culture media. ROS are believed to cause damage to cell membranes and DNA fragmentation in somatic cells. This study was conducted to ascertain the level of H2O2 concentration within embryos and the morphological features of cell damage induced by H2O2. A total of 62 human oocytes and embryos (31 fragmented, 15 non-fragmented embryos, 16 unfertilized oocytes) was obtained from the IVF-embryo transfer programme. The relative intensity of H2O2 concentrations within embryos was measured using 2',7'-dichlorodihydrofluorescein diacetate by Quanti cell 500 fluorescence imaging and DNA fragmentation was observed with transmission electron microscopy and an in-situ apoptosis detection kit. The H2O2 concentrations were significantly higher in fragmented embryos (72.21 +/- 9.62, mean +/- SEM) compared to non-fragmented embryos (31.30 +/- 3.50, P < 0.05) and unfertilized oocytes (30.75 +/- 2.67, P < 0.05). Apoptosis was observed only in fragmented embryos, and was absent in non-fragmented embryos. Electron microscopic findings confirmed apoptotic bodies and cytoplasmic condensation in the fragmented blastomeres. We conclude that there is a direct relationship between increased H2O2 concentration and apoptosis, and that further studies should be undertaken to confirm these findings.      

NEWER CONCEPTS AND MANAGEMENT OF NEONATAL SEPSIS

Despite extensive research into its patho-physiology, investigations and treatment, sepsis remains an important cause of neonatal morbidity and mortality. The incidence in developing countries is 10 times that in the developed world. A large number of pro-and anti-inflammatory cytokines (interleukins, eicosanoids, tumour necrosis factor-alpha, nitric oxide) have been identified, the interplay of which leads to the Systemic Inflammatory Response Syndrome (SIRS) which can have devastating consequences on all systems of the body. In India the common organisms include Staphylococcus, E coli, Klebsiella and Candida. A number of maternal and neonatal risk factors have been identified. The initial signs and symptoms are subtle and can easily be missed. Early investigations and screening tests are important and a promising number of new tests are being studied. The gold standard for diagnosis is a positive culture from a body fluid or local source in the presence of SIRS. The threshold for starting antibiotics should be low in high-risk neonates and broad spectrum antibiotics covering the likely organisms should be given intravenously in all suspected cases in a hospital setting. This should be continued for at least 24-48 hours (till negative reports are available) in suspected cases and for 2-3 weeks in proven cases. Prophylaxis is aimed at preventing nosocomial and cross infections. Strict hand-washing, meticulous asepsis protocols, identification of high risk groups and prompt and better screening tests are essential in controlling this problem.KEY WORDS: Neonate, Sepsis, Systemic inflammatory response syndrome