NOPR Collection:

Pulmonary surfactants and their role in pathophysiology of lung disorders

2013-01-01T00:00:00Z

Title: Pulmonary surfactants and their role in pathophysiology of lung disorders Authors: Akella, Aparna; Deshpande, Shripad B Abstract: Surfactant is an agent that decreases the surface tension between two media. The surface tension between gaseous-aqueous interphase in the lungs is decreased by the presence of a thin layer of fluid known as pulmonary surfactant. The pulmonary surfactant is produced by the alveolar type-II (AT-II) cells of the lungs. It is essential for efficient exchange of gases and for maintaining the structural integrity of alveoli. Surfactant is a secretory product, composed of lipids and proteins. Phosphatidylcholine and phosphatidylglycerol are the major lipid constituents and SP-A, SP-B, SP-C, SP-D are four types of surfactant associated proteins. The lipid and protein components are synthesized separately and are packaged into the lamellar bodies in the AT-II cells. Lamellar bodies are the main organelle for the synthesis and metabolism of surfactants. The synthesis, secretion and recycling of the surfactant lipids and proteins is regulated by complex genetic and metabolic mechanisms. The lipid-protein interaction is very important for the structural organization of surfactant monolayer and its functioning. Alterations in surfactant homeostasis or biophysical properties can result in surfactant insufficiency which may be responsible for diseases like respiratory distress syndrome, lung proteinosis, interstitial lung diseases and chronic lung diseases. The biochemical, physiological, developmental and clinical aspects of pulmonary surfactant are presented in this article to understand the pathophysiological mechanisms of these diseases. Page(s): 5-22

Angiotensin-II down-regulates cardiac natriuretic peptide receptor-A mediated anti-hypertrophic signaling in experimental rat hearts

2013-01-01T00:00:00Z

Title: Angiotensin-II down-regulates cardiac natriuretic peptide receptor-A mediated anti-hypertrophic signaling in experimental rat hearts Authors: Gopi, Venkatachalam; Parthasarathy, Arumugam; Umadevi, Subramanian; Vellaichamy, Elangovan Abstract: Atrial natriuretic peptide (ANP) exerts anti-hypertrophic effects in the heart via natriuretic peptide receptor-A (NPR-A). However, ANP mediated anti-hypertrophic activity is decreased in the cardiomyopathic conditions. In the present investigation the in vivo effects of angiotensin II (Ang II), a hypertrophic agonist have been studied on the ventricular expression level of NPR-A in Wistar rat hearts. NPR-A expression at the protein and mRNA levels were found to be markedly reduced by 5-fold respectively in Ang II infused rats heart as compared with sham rat hearts. Moreover, cGMP production in response to ANP was reduced by 77% in the isolated cardiac membrane preparation from the Ang II infused rat hearts. Losartan treatment reversed NPR-A expression and responsiveness to ANP. This study suggests that Ang II down regulates cardiac NPR-A activity by suppressing Npr1 gene transcription. Page(s): 48-55

In vitro seed germination of economically important edible bamboo Dendrocalamus membranaceus Munro^†

2013-01-01T00:00:00Z

Title: In vitro seed germination of economically important edible bamboo Dendrocalamus membranaceus Munro^† Authors: Brar, Jasmine; Anand, Manju; Sood, Anil Abstract: An in vitro propagation protocol using mature seeds of D. membranaceus was successfully established. Scarcity of seeds in bamboos because of their long flowering periods and irregular seed set resulting in low viability and germination potential, motivated us to undertake the present study. The effects of sterilants, light conditions, exogenous application of plant growth regulators and temperature in overcoming germination barriers in ageing seeds of bamboo were studied. It was found that HgCl₂ (0.1%) along with bleach (15%) was more effective in raising aseptic cultures. Dark conditions, high temperatures around 30 °C and soaking of seeds in GA₃ solution (50 ppm) overnight stimulated high percent of seed germination with corresponding increase in shoot length (2.7±0.7 mm) and number of sprouts (2.1±0.7) per explants during culture initiation. 6-benzylaminopurine acted synergistically with kinetin to give optimum germination rate of 70±13.9% as compared to 63.13% when used individually. For prolonged maintenance of cultures, 2% sucrose was found to be suitable for promoting photomixotrophic micropropagation. Following this procedure, about 65% survival of plantlets could be achieved during hardening. Biochemically seeds consume starchy endosperm for emergence of radicle which is taken as a sign of germination as also evident from the present study. Loss of viability and vigour after a year was confirmed by Tetrazolium chloride test. Micropropagation protocol developed here will ensure regeneration of large number of plants in a relatively short time. Conclusively, in vitro propagation protocol developed in D. membranaceus using mature seeds as an explants is reported for the first time. Page(s): 88-96

Effects of dietary magnesium on testicular histology, steroidogenesis, spermatogenesis and oxidative stress markers in adult rats

2013-01-01T00:00:00Z

Title: Effects of dietary magnesium on testicular histology, steroidogenesis, spermatogenesis and oxidative stress markers in adult rats Authors: Chandra, Amar K; Sengupta, Pallav; Goswami, Haimanti; Sarkar, Mahitosh Abstract: The available information on the effect of excess dietary magnesium on male reproduction is inadequate, though consumption of hard water rich in magnesium salt is not uncommon in many geographical areas. The present study has thus been undertaken to evaluate the morphological as well as cytological and functional changes in testis of magnesium administered sexually mature male Wistar rats. Significant increase in the activities of androgenic enzymes viz. Δ⁵3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase with concomitant increase in serum testosterone level, followed by progressive development in cytoarchitechture of genital organs, without any significant alteration in quantitative spermatogenesis were observed. The results were more marked in the groups treated for longer duration. The results further suggests that the changes that occurred after excessive magnesium in testis were not for the enhanced adrenocortical activities or for the generation of oxidative stress in reproductive organs, but for the direct action of excess magnesium on male gonads. Magnesium supplementation thus has an apparent beneficial effect on male gonadal system. Page(s): 37-47

NOPR Collection:

Pulmonary surfactants and their role in pathophysiology of lung disorders

Angiotensin-II down-regulates cardiac natriuretic peptide receptor-A mediated anti-hypertrophic signaling in experimental rat hearts

In vitro seed germination of economically important edible bamboo Dendrocalamus membranaceus Munro†

Effects of dietary magnesium on testicular histology, steroidogenesis, spermatogenesis and oxidative stress markers in adult rats

In vitro seed germination of economically important edible bamboo Dendrocalamus membranaceus Munro^†