Increased leptin-b expression and metalloprotease expression contributed to the pyridoxine-associated toxicity in zebrafish larvae displaying seizure-like behavior.

Epilepsy is a common neurological disorder affecting people of all ages, races and ethnic backgrounds world-wide. Vitamin B6 supplementation has been widely used as an adjuvant for treating epilepsy. However, the adverse effects, including nausea and peripheral sensory neuropathy, caused by long-term and high-dose consumption of vitamin B6 have undermined the usefulness of vitamin B6 supplementation, justifying additional experimental scrutiny of vitamin B6-associated toxicity. In the current study, we found that the presence of pyridoxine, the inactive form of B6 vitamer included in most nutrient supplements, increased the mortality of the larvae displaying chemical-induced epilepsy. The expression of leptin-b, one zebrafish ortholog of human leptin, was significantly increased in the larvae displaying seizures. Increased leptin-b expression alleviated larval seizure-like behavior when exposed to epilepsy inducer, but also increased larval mortality in the presence of pyridoxine. Meanwhile, elevated adam17 and mmp13 mRNA level were found in the larvae simultaneously exposed to epilepsy-inducer and pyridoxine. Adding TNF-α inhibitor and mmp13 inhibitor effectively improved the survival of larvae injected with leptin-b mRNA and exposed to pyridoxine subsequently. We conclude that increased leptin-b and metalloprotease expression contributed, at least partly, to the pyridoxine-associated toxicity observed in larvae displaying seizures.

Prognostic impact of renin-angiotensin system blockade in esophageal squamous cell carcinoma.

INTRODUCTION: The aim of this study is to evaluate whether the administration of renin-angiotensin system (RAS) inhibitors, angiotensin-I converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs), is associated with treatment outcome in patients with esophageal squamous cell carcinoma. MATERIALS AND METHODS: A total of 141 esophageal squamous cell carcinoma patients receiving esophagectomy were identified, and were divided into two groups: an ACEI/ARB group (n=20), and a non-ACEI/ARB group (n=121). The effect of ACEIs or ARBs on cell proliferation and vascular endothelial growth factor (VEGF) secretion of esophageal squamous cell carcinoma cell lines, CE81T/VGH and TE2, were investigated by 3-(4.5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and Enzyme-linked immunosorbent assay (ELISA), respectively. RESULTS: Use of ACEI/ARB (p=0.032), pathologic T stage (p<0.001), pathologic N stage (p=0.012), tumor stage (p=0.006), and tumor location (p=0.032) were significantly associated with superior overall survival. In multivariate comparison, use of ACEI/ARB (p=0.006), tumor stage (p=0.002), and tumor location (p=0.014) represented the independent prognosticators of superior overall survival. In cell lines, ACEIs/ARBs inhibit cell proliferation and VEGF secretion in a dose-dependent manner. CONCLUSIONS: ACEIs/ARBs administration is independently associated with superior overall survival in patients with esophageal squamous cell carcinoma receiving esophagectomy. Our data support further investigation of the role of RAS inhibitors as a potential therapy in esophageal squamous cell carcinoma.

Heme oxygenase-1 plays a pro-life role in experimental brain stem death via nitric oxide synthase I/protein kinase G signaling at rostral ventrolateral medulla.

BACKGROUND: Despite its clinical importance, a dearth of information exists on the cellular and molecular mechanisms that underpin brain stem death. A suitable neural substrate for mechanistic delineation on brain stem death resides in the rostral ventrolateral medulla (RVLM) because it is the origin of a life-and-death signal that sequentially increases (pro-life) and decreases (pro-death) to reflect the advancing central cardiovascular regulatory dysfunction during the progression towards brain stem death in critically ill patients. The present study evaluated the hypothesis that heme oxygnase-1 (HO-1) may play a pro-life role as an interposing signal between hypoxia-inducible factor-1 (HIF-1) and nitric oxide synthase I (NOS I)/protein kinase G (PKG) cascade in RVLM, which sustains central cardiovascular regulatory functions during brain stem death. METHODS: We performed cardiovascular, pharmacological, biochemical and confocal microscopy experiments in conjunction with an experimental model of brain stem death that employed microinjection of the organophosphate insecticide mevinphos (Mev; 10 nmol) bilaterally into RVLM of adult male Sprague-Dawley rats. RESULTS: Western blot analysis coupled with laser scanning confocal microscopy revealed that augmented HO-1 expression that was confined to the cytoplasm of RVLM neurons occurred preferentially during the pro-life phase of experimental brain stem death and was antagonized by immunoneutralization of HIF-1α or HIF-1ß in RVLM. On the other hand, the cytoplasmic presence of HO-2 in RVLM neurons manifested insignificant changes during both phases. Furthermore, immunoneutralization of HO-1 or knockdown of ho-1 gene in RVLM blunted the augmented life-and-death signals exhibited during the pro-life phase. Those pretreatments also blocked the upregulated pro-life NOS I/PKG signaling without affecting the pro-death NOS II/peroxynitrite cascade in RVLM. CONCLUSIONS: We conclude that transcriptional upregulation of HO-1 on activation by HIF-1 in RVLM plays a preferential pro-life role by sustaining central cardiovascular regulatory functions during brain stem death via upregulation of NOS I/PKG signaling pathway. Our results further showed that the pro-dead NOS II/peroxynitrite cascade in RVLM is not included in this repertoire of cellular events.