Publications by authors named "Chandra Sekhar Ravuri"

5 Publications

  • Page 1 of 1

Seasonal Differences in Relative Gene Expression of Putative Central Appetite Regulators in Arctic Charr (Salvelinus alpinus) Do Not Reflect Its Annual Feeding Cycle.

PLoS One 2015 30;10(9):e0138857. Epub 2015 Sep 30.

Department of Arctic and Marine Biology, UiT-The Arctic University of Norway, Tromsø, Norway.

The highly seasonal anadromous Arctic charr (Salvelinus alpinus) was used to investigate the possible involvement of altered gene expression of brain neuropeptides in seasonal appetite regulation. Pro-opiomelanocortin (POMCA1, POMCA2), Cocaine and amphetamine regulated transcript (CART), Agouti related Peptide (AgRP), Neuropeptide Y (NPY) and Melanocortin Receptor 4 (MC4-R) genes were examined. The function of centrally expressed Leptin (Lep) in fish remains unclear, so Lep (LepA1, LepA2) and Leptin Receptor (LepR) genes were included in the investigation. In a ten months study gene expression was analysed in hypothalamus, mesencephalon and telencephalon of immature charr held under natural photoperiod (69°38'N) and ambient temperature and given excess feed. From April to the beginning of June the charr did not feed and lost weight, during July and August they were feeding and had a marked increase in weight and condition factor, and from November until the end of the study the charr lost appetite and decreased in weight and condition factor. Brain compartments were sampled from non-feeding charr (May), feeding charr (July), and non-feeding charr (January). Reverse transcription real-time quantitative PCR revealed temporal patterns of gene expression that differed across brain compartments. The non-feeding charr (May, January) had a lower expression of the anorexigenic LepA1, MC4-R and LepR in hypothalamus and a higher expression of the orexigenic NPY and AgRP in mesencephalon, than the feeding charr (July). In the telencephalon, LepR was more highly expressed in January and May than in July. These results do not indicate that changes in central gene expression of the neuropeptides investigated here directly induce seasonal changes in feeding in Arctic charr.
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May 2016

Complete regression and systemic protective immune responses obtained in B16 melanomas after treatment with LTX-315.

Cancer Immunol Immunother 2014 Jun 28;63(6):601-13. Epub 2014 Mar 28.

Lytix Biopharma AS, P.O. Box 6447, 9294, Tromsø, Norway.

Malignant melanoma is the most aggressive and deadliest form of skin cancer due to its highly metastatic potential, which calls for new and improved therapies. Cationic antimicrobial peptides (CAPs) are naturally occurring molecules found in most species, in which they play a significant role in the first line of defense against pathogens, and several CAPs have shown promising potential as novel anticancer agents. Structure-activity relationship studies on the CAP bovine lactoferricin allowed us to de novo design short chemically modified lytic anticancer peptides. In the present study, we investigated the in vivo antitumor effects of LTX-315 against intradermally established B16 melanomas in syngeneic mice. Intratumoral administration of LTX-315 resulted in tumor necrosis and the infiltration of immune cells into the tumor parenchyma followed by complete regression of the tumor in the majority of the animals. LTX-315 induced the release of danger-associated molecular pattern molecules such as the high mobility group box-1 protein in vitro and the subsequent upregulation of proinflammatory cytokines such as interleukin (IL) 1β, IL6 and IL18 in vivo. Animals cured by LTX-315 treatment were protected against a re-challenge with live B16 tumor cells both intradermally and intravenously. Together, our data indicate that intratumoral treatment with LTX-315 can provide local tumor control followed by protective immune responses and has potential as a new immunotherapeutic agent.
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June 2014

Long-term fasting in the anadromous Arctic charr is associated with downregulation of metabolic enzyme activity and upregulation of leptin A1 and SOCS expression in the liver.

J Exp Biol 2013 Sep 16;216(Pt 17):3222-30. Epub 2013 May 16.

Faculty of Biosciences, Fisheries and Economy, Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway.

The life strategy of the anadromous Arctic charr (Salvelinus alpinus) includes several months of voluntary fasting during overwintering in freshwater, leading to emaciation prior to seawater migration in spring. In this study we compared changes in condition, substrate utilization and liver metabolism between captive anadromous charr subjected to food deprivation during late winter and spring, and conspecifics fed in excess. In March, nine out of the 10 sampled fed fish had not eaten, indicating that they were in a voluntary anorexic state. In June, the fed fish were eating and all had higher body mass, condition factor and adiposity than in March. In fasted fish there were only small decreases in body mass, condition factor and adiposity between March and May, but all these parameters decreased markedly from May to June. The fasted fish were depleted in fat and glycogen in June, had suppressed activity of hepatic enzymes involved in lipid metabolism (G6PDH and HOAD) and seemed to rely on protein-derived glucose as a major energy source. This was associated with upregulated liver gene expression of leptin A1, leptin A2, SOCS1, SOCS2 and SOCS3, and reduced IGF-I expression. In an in vitro study with liver slices it was shown that recombinant rainbow trout leptin stimulated SOCS1 and SOCS3 expression, but not SOCS2, IGF-I or genes of enzymes involved in lipid (G6PDH) and amino acid (AspAT) metabolism. It is concluded that liver leptin interacts with SOCS in a paracrine fashion to suppress lipolytic pathways and depress metabolism when fat stores are depleted.
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September 2013

A cross-sectional study of visual impairment in elderly population in residential care in the South Indian state of Andhra Pradesh: a cross-sectional study.

BMJ Open 2013 Mar 15;3(3). Epub 2013 Mar 15.

Allen Foster Community Eye Health Research Centre, International Centre for Advancement of Rural Eye care, L V Prasad Eye Institute, Hyderabad, Andhra Pradesh, India.

Objective: To assess the prevalence and major causes of visual impairment (VI) in elderly residents of 'home for the aged' institutions in the Prakasam district in India.

Design: Cross-sectional study.

Setting: 'Home for the aged' institutions in the Prakasam district in the South Indian state of Andhra Pradesh.

Participants: All 524 residents in the 26 'homes for aged' institutions in the district were enumerated.

Primary And Secondary Outcome Measures: Prevalence and causes of VI; visual acuity (VA) was assessed using a Snellen chart at a distance of 6 m. Pinhole VA was assessed if presenting VA was <6/18. Torchlight examination and direct ophthalmoscopy were performed. VI was defined as presenting VA <6/18 in the better eye.

Results: Of the 494 participants examined (response rate 94.3%), 78.1% were women, 72.1% had no formal schooling. The mean age of participants was 70 years (SD ±8.6 years). VI was present in 280/494 individuals (56.9%; 95% CI 52.3 to 61.3). Over 80% of the VI was due to avoidable causes including cataract (57.1%) and uncorrected refractive errors (26.4%). Among 134 individuals who had undergone bilateral cataract surgery, only 78 (58.2%) individuals had presenting VA ≥6/18 and 13/134 (9.7%) participants were blind.

Conclusions: There is high prevalence of VI in the institutionalised elderly population in the Prakasam district in India. A significant proportion of this elderly population with VI can benefit from spectacles and cataract surgery. Strategies are required to provide high-quality services to this population.
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March 2013

Seasonal appetite regulation in the anadromous Arctic charr: evidence for a role of adiposity in the regulation of appetite but not for leptin in signalling adiposity.

Gen Comp Endocrinol 2012 Sep 23;178(2):330-7. Epub 2012 Jun 23.

Faculty of Biosciences, Fisheries and Economy, University of Tromsø, N-9037 Tromsø, Norway.

The aim of this study was to investigate whether the seasonal feeding cycle of the anadromous Arctic charr (Salvelinus alpinus) is regulated by a lipostatic mechanism and if leptin (Lep) might act as an endocrine signal of adiposity. Offspring of anadromous Arctic charr with a body mass of 121 g were divided into two treatment groups; one was given feed in excess from March to November, and the other was fasted between April and early June and fed in excess thereafter. In the continuously fed group there was an 8-fold increase in body mass, and a doubling of percentage body fat, from March to August, after which there was no further increase. Fish in the other group lost weight and body fat during fasting, but grew rapidly on being fed, and had partially compensated for their deficit in body mass by August. Differences in percentage body fat between treatment groups were eliminated by August, providing evidence for a lipostatic regulation of feeding and energy homeostasis in Arctic charr. Neither liver total LepA gene expression nor plasma Lep concentrations correlated positively with fish adiposity, so there was no evidence that Lep acts as a signal of adiposity in this species. On the other hand, there was a strong increase in liver LepA1 gene expression at the end of the fasting period, concomitant with fat mobilization and increased plasma glucose, indicating that LepA1 may play a role in regulating metabolic processes associated with fasting.
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September 2012