Anti-HLA class I antibody-mediated activation of the PI3K/Akt signaling pathway and induction of Bcl-2 and Bcl-xL expression in endothelial cells

Anti-human leukocyte antigen (HLA) antibodies (Ab) have long been implicated in the process of acute and chronic allograft rejection, yet their mechanism(s) of action is not well understood. The aim of this study was to determine whether ligation of HLA class I molecules by anti-HLA Ab on the surface of human endothelial cells (EC) activates the PI3 Kinase (PI3K)/Akt signaling pathway and downstream target proteins of the cell death apparatus. We report that Ab ligation of major histocompatibility complex (MHC) class I molecules on the surface of EC triggers phosphorylation of Akt, PI3K, and recruitment of PI3K and Akt into a signaling unit with focal adhesion kinase. Signaling through class I also stimulated phosphorylation of Bad and upregulated expression of Bcl-2 and Bcl-xL. Pretreatment of EC with the PI3K inhibitor wortmannin blocked class I-mediated expression of Bcl-2, but not Bcl-xL, suggesting a role for the PI3K/Akt signaling pathway in regulation of class I-induced Bcl-2 expression. The intracellular events initiated by class I ligation were influenced by the concentration of the anti-HLA Ab with the lowest tested concentrations of Ab stimulating the highest level of Akt phosphorylation, Bcl-xL and Bcl-2 expression. Consistent with the in vitro experiments, analysis of biopsy samples from heart transplant recipients with evidence of Ab-mediated rejection exhibited increased Bcl-2 expression on the vascular endothelium. These results suggest that exposure of the graft endothelium to low concentrations of anti-HLA Ab may promote cell survival by transducing signals resulting in upregulation of cell survival genes.     

Antitumor activity and antioxidant role of Bauhinia racemosa against Ehrlich ascites carcinoma in Swiss albino mice [corrected]

AIM: To study the antitumor effect and antioxidant role of Bauhinia racemosa. METHODS: Antitumor activity and antioxidant status of methanol extract (50, 100, and 200 mg/kg) of Bauhinia racemosa stem bark was evaluated against Ehrlich ascites carcinoma (EAC) tumor in mice. Acute and short-term toxicity studies were performed initially in order to ascertain the safety of methanol extract of Bauhinia racemosa (MEBR). After 24 h of tumor inoculation, the extract was administered daily for 14 d. After administration of the last dose followed by 18 h fasting, mice were then sacrificed for observation of antitumor activity. The effect of MEBR on the growth of transplantable murine tumor, life span of EAC bearing hosts and simultaneous alterations in the hematological profile and liver biochemical parameters (lipid peroxidation, antioxidant enzymes) were estimated. RESULTS: The MEBR showed decrease in tumor volume, packed cell volume and viable cell count, and increased the nonviable cell count and mean survival time thereby increasing life span of EAC tumor bearing mice. Hematological profile reverted to more or less normal levels in extract treated mice. Treatment with MEBR decreased the levels of lipid peroxidation and increased the levels of glutathione, superoxide dismutase and catalase. CONCLUSION: The methanol extract of Bauhinia racemosa stem bark exhibited antitumor effect by modulating lipid peroxidation and augmenting antioxidant defense system in EAC bearing mice.     

Rhabdoid Tumor of the Kidney Is a Component of the Rhabdoid Predisposition Syndrome

The rhabdoid predisposition syndrome (RPS) is characterized by pedigrees in which two or more individuals carry germline mutations of the hSNF5/INI1 tumor suppressor gene. The tumors associated with the syndrome include atypical teratoid/rhabdoid tumor (AT/RT), choroid plexus carcinoma, medulloblastoma, and extrarenal rhabdoid tumor. Rhabdoid tumor of the kidney (RTK) has not been described as part of the RPS. We report a case of a 7-month-old boy with RTK whose sister had a malignant cerebellar tumor followed by a malignant lung and pleural tumor of childhood with typical rhabdoid histology. Molecular genetic analysis of the RTK and tissue from the pleural tumor revealed in both cases identical nonsense mutations of the hSNF5/INI1 gene on chromosome 22q11.2, where thymidine was substituted for cytosine in base 472. The proband had an identical germline mutation. This is the fifth genetically analyzed RPS pedigree and the first to include an RTK.     

Evaluation of anti-inflammatory activity of chloroform extract of Bryonia laciniosa in experimental animal models

The anti-inflammatory effect of the leaves of Bryonia laciniosa was evaluated using carrageenan, dextran, histamine, serotonin induced rat paw oedema and cotton pellet induced granuloma (chronic) models in rats. In mice, carrageenan peritonitis test was performed for the extract by oral administration. The chloroform extract of Bryonia laciniosa (CEBL) exhibited significant anti-inflammatory effect at the dose 50, 100 and 200 mg/kg. Maximum inhibition (52.4%) was noted at the dose of 200 mg/kg after 3 h of drug treatment in carrageenan induced paw oedema, whereas the indomethacin (standard drug) produced 62.1% of inhibition. The extract exhibited significant anti-inflammatory activity in dextran induced paw oedema in a dose dependent manner. The extract also exhibited significant inhibition on the hind paw oedema in rats caused by histamine and serotonin respectively. In the chronic model (cotton pellet induced granuloma) the CEBL (200 mg/kg) and standard drug showed decreased formation of granuloma tissue by 50.1 and 57.3% (p<0.001) respectively. The extract also inhibited peritoneal leukocyte migration in mice. Thus, the present study revealed that the chloroform extract of Bryonia laciniosa exhibited significant anti-inflammatory activity in the tested models.     

Mitochondrial tubulopathy: the many faces of mitochondrial disorders

We report a rare presentation of mitochondrial disorder in a child with recurrent carpopedal spasms due to hypocalcemia and hypomagnesemia, secondary to renal proximal tubulopathy and possible hypoparathyroidism. At least two mutant mitochondrial DNA species were identified, and abnormal mitochondria were found in the muscle and renal biopsy specimens. The case illustrates the spectrum and diversity of mitochondrial presentations, arising because of heteroplasmy of mutations and the type of organs affected. Received: 31 October 2000 / Revised: 16 April 2001 / Accepted: 17 April 2001     

Targeting oxidative stress component in the therapeutics of epilepsy

The role of free radical-mediated reactions in human neuropathology continues to attract significant interest. Oxidative injury produced by free radicals may play a role in the initiation and progression of epilepsy and, therapies aimed at reducing oxidative stress may ameliorate tissue damage and favorably alter the clinical course. The prevalence of epilepsy increases with age, and mitochondrial oxidative stress is a leading mechanism of aging and age-related degenerative disease, signifying a further involvement of mitochondrial dysfunction in seizure generation. Oxidative stress occurs when the generation of reactive oxygen species in a system exceeds the body's ability to neutralize and eliminate them, thus creating an imbalance or over abundance of free radicals. Therefore, it is imperative to maintain oxidative balance and control in the brain, and this is tightly regulated by antioxidants. In the last two decades, there has been an explosive interest in the role of antioxidants or neuroprotectants in clinical as well as experimental models of epilepsy. In this regard, the present review is intended to discuss the current state of knowledge pertaining to neuroprotection in epileptic conditions by employing diverse chemical agents including conventional as well as novel anti-epileptic drugs, and to highlight the efficacy of distinct neuroprotective strategies for preventing or treating epilepsy.     

Effect of Bauhinia racemosa stem bark on N-nitrosodiethylamine-induced hepatocarcinogenesis in rats

The aim of this study is to investigate the antioxidant defense system induced by the methanol extract of Bauhinia racemosa L.(MEBR) against N-nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis in Wister albino rats. The effects of MEBR on surface visible macroscopic (Morphometry) liver lesions (neoplastic nodules) and the levels of serum enzymes, lipid peroxidation and antioxidants were evaluated in NDEA-induced hepatocarcinogenesis in rats. In rats treated, with NDEA, significantly elevated levels of serum enzymes (SGOT, SGPT and ALP), bilirubin and decreased levels of protein and uric acid were observed. Significantly elevated amount of malondialdehyde (MDA), the end product of lipidperoxidation, indicated higher levels of lipid peroxidation, which was accompanied by significantly decreased levels of antioxidants like vitamin C, vitamin E, reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT). Administration of MEBR was able to suppress nodule development/hepatocellular lesion formation in rats. The extract treatment increases in antioxidant levels and dramatic decreases in lipid peroxidation levels. MEBR also produced a protective effect by decreasing the level of serum enzymes, bilirubin and increased the protein and uric acid levels. The results suggest that MEBR exert chemopreventive effects by suppressing nodule development and decreasing lipid peroxidation and enhancing the levels of antioxidants in NDEA carcinogenesis by reducing the formation of free radicals.