Biomedical subjects

Premalatha Balachandran

Publications and source records attributed to Premalatha Balachandran.

6 recordsLinked to original sources

PubMed2006

Toll-like receptor 2-dependent activation of monocytes by Spirulina polysaccharide and its immune enhancing action in mice.

We reported previously that a high molecular weight polysaccharide fraction (Immulina) from Spirulina was a potent activator of NF-kappa B and induced both IL-1 beta and TNF-alpha mRNAs in THP-1 human monocytes. In the present study, we show that NF-kappa B activation by Immulina is suppressed by antibodies to CD14 and TLR2 but not by antibodies to TLR4. Similarly, NF-kappa B directed luciferase expression was enhanced by Immulina treatment when cells were co-transfected with vectors expressing proteins supporting TLR2- (CD14 and TLR2) but not TLR4-(CD14, TLR4, and MD-2) dependent activation. Mice that consumed a chemically defined chow mixed with an extract containing Immulina exhibited changes in several immune parameters. The ex vivo production of IgA and IL-6 from Peyer's patch cells was enhanced 2-fold and interferon-gamma production from spleen cells was increased 4-fold in Immulina-treated mice. The enhanced production of these factors was most notable with mice that had consumed this extract for 4 or 5 days. These studies shed light on how Immulina activates cells of the innate immune system and suggests that oral consumption of this polysaccharide can enhance components within both the mucosal and systemic immune systems.

Animals↗

PubMed2005

Melanin: dietary mucosal immune modulator from Echinacea and other botanical supplements.

The agents responsible for the therapeutic effects of many botanical supplements have not been established in spite of their popularity. Here we show that melanin is a previously unrecognized immunostimulatory compound that is a major component of botanicals traditionally used to enhance immune function. While melanin is present in commonly consumed vegetables, its specific activity is several orders of magnitude less than melanin extracted from these botanicals. The major reason that this agent has eluded detection is its solvent-specific requirement for extraction/solubility. Melanin activates NF-kappa B in monocytes in vitro through a toll-like receptor 2-dependent process. Ingestion of melanin by mice for four days increases production ex vivo of interferon-gamma by spleen cells and IgA and interleukin-6 by Peyer's patch cells. The identification of this new class of mucosal immune stimulants will allow further characterization of botanical products and advances our understanding of the basis for their traditional use.

Animals↗

PubMed2005

Cancer--an ayurvedic perspective.

An integrated approach is needed to manage cancer using the growing body of knowledge gained through scientific developments. Thousands of herbal and traditional compounds are being screened worldwide to validate their use as anti-cancerous drugs. The science of Ayurveda is supposed to add a step on to the curative aspects of cancers that have resemblance with clinical entities of arbuda and granthi mentioned in Sushrutha samhita. Hence, an attempt is made in this review to discuss about the pathology and therapeutic management of various cancers described in Ayurveda. Review of literature on anticancer drugs of plant origin revealed identification of newer ayurvedic drugs that are not mentioned in the ancient texts. These new findings add up to ayurvedic science that has been developed through ages. In addition, details of experimental and clinical studies conducted on single and compound ayurvedic preparations for their anticancer efficacy strongly emphasize ayurvedic therapy as a scientifically driven one and not simply unconventional.

Antineoplastic Agents, Phytogenic↗

PubMed2005

Structure activity relationships of aristolochic acid analogues: toxicity in cultured renal epithelial cells.

BACKGROUND: Aristolochia species are nephrotoxic and carcinogenic. Recent studies showed that aristolochic acid (AA) could induce acute renal failure and tubular lesions in several species and available evidences demonstrate the unequivocal role of AA in so called Chinese herbs nephropathy. METHODS: A series of AA derivatives isolated from Aristolochia spp. were analyzed for their nephrotoxic potential using the neutral red dye exclusion assay in cultures of LLC-PK(1) cells. The structural relationships between AA I and its analogues were compared with their cytotoxic effects to predict structural determinants for AA toxicity. Further, caspase-3 assay was performed on toxic compounds to determine if caspases, the enzymes that play a critical role in apoptosis are involved in AA-induced cytotoxicity. RESULTS: AA I was found to be most toxic followed by AA II, AA VIIIa, and AA Ia in decreasing levels of toxicity. The other compounds, nitrophenanthrene carboxylic acid analogues of AA I, aristolactams, and other derivatives did not exhibit considerable toxicity. The results showed significant relationships between cytotoxicity of AA compounds and the localization of functional groups in their structure. Analogues containing hydroxyl groups diminished cytotoxicity. The demethylated analogues of AA I are markedly less active. The negative impact on cytotoxicity was found on nitroreduction of AA I. AA induced caspase activation was also observed. CONCLUSION: These cytotoxic data suggest that the nitro and methoxy groups are critical determinants of nephrotoxicologic potency of AA.

Animals↗

PubMed2004

Role of intracellular Ca2+ in the expression of the amiloride-sensitive epithelial sodium channel.

The amiloride-sensitive epithelial sodium channel (ENaC), a multimeric plasma membrane protein composed of alpha-, beta-, and gamma-ENaC subunits, mediates Na(+) reabsorption in epithelial tissues, including the distal nephron, colon, lung, and secretory glands, and plays a critical role in pathophysiology of essential hypertension and cystic fibrosis (CF). The function of ENaC is tightly regulated by signals elicited by aldosterone, vasopressin, agents that increase intracellular cAMP levels, ions, ion channels, G-protein-coupled mechanisms, and cytoskeletal proteins. In this paper, the effects of Ca(2+) on the expression of the human ENaC subunits expressed in human embryonic kidney cells (HEK-293 cells) were examined. Incubation of cells with increased extracellular Ca(2+) and treatment of cells with A23187 and thapsigargin stimulated the expression of the monomeric ENaC subunits. Treatment of cells with Ca(2+)-chelating agents, EGTA and BAPTA-AM, reduced the levels of ENaC subunit expression. The pulse-chase experiments suggested that a rise in the intracellular Ca(2+) increases the ENaC subunit expression. Immunoblot analysis using the anti-ubiquitin antibody indicated that ENaC undergoes ubiquitination. A correlation between the processes that regulate ENaC function with the intracellular Ca(2+) was discussed.

Amino Acid Sequence↗

PubMed2001

Activation of large conductance sodium channels upon expression of amiloride-sensitive sodium channel in Sf9 insect cells.

The amiloride-sensitive epithelial sodium channels (ENaC) mediate Na(+) reabsorption in epithelial tissues including distal nephron, colon, lung, and secretory glands and plays a critical role in pathophysiology of hypertension and cystic fibrosis. The ENaC is a multimeric protein composed of alpha-ENaC, beta-ENaC, and gamma-ENaC subunits. To study the biochemical properties of the channel, the subunit cDNAs of rat colon ENaC (rENaC) were subcloned into baculoviruses, and the corresponding proteins were expressed in Sf9 insect cells. The functional characteristics of the expressed rENaC were studied in planar lipid bilayers. The results show that expression of alpha-rENaC and alphabetagamma-rENaC in Sf9 insect cells results in the generation of cation-selective large conductance channels. Although the large conductance channels observed in the alpha-rENaC-containing membranes were unaffected by amiloride, the large conductance channels found in alphabetagamma-rENaC complex-containing membranes exhibited voltage-dependent flickering in the presence of micromolar amiloride. Possible implications of these observations are discussed.

Animals↗