Stage-specific expression of dynein light chain-1 and its interacting kinase, p21-activated kinase-1, in rodent testes: implications in spermiogenesis.

Mammalian spermatogenesis is a complex process involving regulatory interactions of many gene products. In this study, we found that dynein light chain-1 (DLC1), a component of the dynein motor complex, is highly expressed in mouse and rat testes. Immunohistochemically detectable levels of DLC1 are observed specifically in spermatids in steps 9-16 in distinct subcellular compartments: in steps 9-11, DLC1 is predominantly localized in the nucleus; in steps 12 and 13, it is found in both nucleus and cytoplasm; and in step 14-16, it is present exclusively in the cytoplasm. In addition, we found p21-activated kinase 1 (Pak1), a protein kinase that activates DLC1 by phosphorylating DLC1 at Serine 88, was also expressed during these stages of spermatogenesis. Pak1 was also expressed in Leydig cells, in preleptotene primary spermatocytes, and in round spermatids. The spermiogenic stage-specific expression of DLC1 suggests a role for DLC1 in chromatin condensation, spermatid shaping, and the final release of sperm from the spermatogenic epithelium. Further, Pak1 may also play a role in spermiogenesis by regulating DLC1 phosphorylation and, consequently, its function.     

Antioxidant activity of fractionated extracts of rhizomes of high-altitude Podophyllum hexandrum: Role in radiation protection

Whole extract of rhizomes of Podophyllum hexandrum has been reported earlier by our group to render whole-body radioprotection. High-altitude P. hexandrum (HAPH) was therefore fractionated using solvents of varying polarity (non-polar to polar) and the different fractions were designated as, n-hexane (HE), chloroform (CE), alcohol (AE), hydro-alcohol (HA) and water (WE). The total polyphenolic content (mg% of quercetin) was determined spectrophotometrically, while. The major constituents present in each fraction were identified and characterized using LC-APCI/MS/MS. In vitro screening of the individual fractions, rich in polyphenols and lignans, revealed several bioactivities of direct relevance to radioprotection e.g. metal-chelation activity, antioxidant activity, DNA protection, inhibition of radiation (250 Gy) and iron/ascorbate-induced lipid peroxidation (LPO). CE exhibited maximum protection to plasmid (pBR322) DNA in the plasmid relaxation assay (68.09% of SC form retention). It also showed maximal metal chelation activity (41.59%), evaluated using 2,2-bipyridyl assay, followed by AE (31.25%), which exhibited maximum antioxidant potential (lowest absorption unit value: 0.0389± 0.00717) in the reducing power assay. AE also maximally inhibited iron/ascorbate-induced and radiation-induced LPO (99.76 and 92.249%, respectively, at 2000 g/ml) in mouse liver homogenate. Under conditions of combined stress (radiation (250 Gy) + iron/ascorbate), at a concentration of 2000 g/ml, HA exhibited higher percentage of inhibition (93.05%) of LPO activity. HA was found to be effective in significantly (p < 0.05) lowering LPO activity over a wide range of concentrations as compared to AE. The present comparative study indicated that alcoholic (AE) and hydro-alcoholic (HA) fractions are the most promising fractions, which can effectively tackle radiation-induced oxidative stress.     

Epidemiology of typhoid carriers among blood donors and patients with biliary, gastrointestinal and other related diseases

Enteric fever due to Salmonella Typhi is a major public health problem. Typhoid carriers have high titres of Vi agglutinins in their sera. We worked out the baseline data for Vi agglutinins from 705 healthy blood donors (controls) by ELISA and compared it with 446 patients with biliary, gastrointestinal and other related diseases (cases). The samples were divided into five groups based on the disease condition of the patients from whom they were collected. Group A (n=196) consisted of patients with stones in the gall bladder/common bile duct and Group B (n=27) with gall bladder carcinoma. Group C (n=33) comprised patients with carcinoma of the pancreas/ampulla, obstructive jaundice and/or cholangiocarcinoma. Group D (n=112) had patients with acute/chronic pancreatitis, abdominal pain, intestinal obstruction, peritonitis, carcinoma oesophagus, chronic diarrhoea, gastrointestinal bleeding and dyspepsia. Group E (n=78) included patients with miscellaneous diseases. The mean absorbance value obtained for healthy subjects +3 standard deviations was taken as the cut-off value for a positive typhoid carrier. In Group A, 10.2% samples were positive; in Group B, 7.4%; in Group C, 12.0%; in Group D, 9.8% and in Group E, 9.0%. There was a highly significant (P <0.001) increase in the presence of Vi agglutinins in the cases compared to the controls. High prevalence of typhoid carriers occurs in patients with biliary, gastrointestinal and other related diseases. Vi serology employing highly purified Vi antigen offers a practical and cost-effective way of screening for S. Typhi carriers.     

Steroid hormone receptor signaling in tumorigenesis

Excessive activation of the hormone signaling pathways is implicated in several disorders of the target tissues, with cancer being one of the most serious fallouts. Steroid hormone receptors are key proteins through which steroid hormones convey their signals to the cells. Deregulated activity of the hormone receptors due to their altered activation; stability or sub-cellular localization is heavily implicated in the onset and progress of cancers. The role played by estrogen and its receptors in breast cancer remains the most thoroughly investigated steroid-dependent cancer system till date. Choosing it as an example, we have summarized the molecular mechanisms underlying the action of the estrogen receptors (ERs) in manifesting the effects of the estrogens in the cells. A special emphasis is placed on the molecular mechanism of their functionality, role of the coactivator proteins, and the reasons for the deregulated signaling. The therapeutic approaches resulting from the mechanistic study of the ER action and their efficacies are also discussed.     

Glycolipids and other constituents from Desmodium gangeticum with antileishmanial and immunomodulatory activities

Nineteen compounds of various classes, such as flavonoid glycosides, pterocarpanoids, lipids, glycolipids, and alkaloids, were isolated and identified from the Desmodium gangeticum whole plant. Aminoglucosyl glycerolipid (8) is reported here for the first time. Its structure has been elucidated by spectroscopic and degradation studies. This novel compound exhibited in vitro antileishmanial and immunomodulatory activities, as it enhanced nitric oxide (NO) production and provided resistance against infection established in peritoneal macrophages by the protozoan parasite Leishmania donovani. Another known compound, glycosphingolipid (cerebroside) (7) was found to possess significant in vitro antileishmanial and immunomodulatory activities against the same parasite. Other compounds were found to be inactive.     

Antitubercular agents. Part 1: synthesis of phthalimido- and naphthalimido-linked phenazines as new prototype antitubercular agents

The preparation and antitubercular properties of a series of phthalimido- and naphthalimido-linked phenazines are described. Some of these new compounds inhibited the growth of Mycobacterium tuberculosis ATCC 27294, Mycobacterium avium ATCC 49601, Mycobacterium intracellulare ATCC 13950 and some clinical isolates.     

Synthesis and in vitro anti-mycobacterial activity of 5-substituted pyrimidine nucleosides

Mycobacterium tuberculosis and Mycobacterium avium infections cause the two most important mycobacterioses, leading to increased mortality in patients with AIDS. Various 5-substituted 2′-deoxyuridines, uridines, 2′-O-methyluridine, 2′-ribofluoro-2′-deoxyuridines, 3′-substituted-2′,3′-dideoxy uridines, 2′,3′-dideoxyuridines, and 2′,3′-didehydro-2′,3′-dideoxyuridines were synthesized and evaluated for their in vitro inhibitory activity against M. bovis and M. avium. 5-(C-1 Substituted)-2′-deoxyuridine derivatives emerged as potent inhibitors of M. avium (MIC₉₀ = 1–5 μg/mL range). The nature of C-5 substituents in the 2′-deoxyuridine series appeared to be a determinant of anti-mycobacterial activity. This new class of inhibitors could serve as useful compounds for the design and study of new anti-tuberculosis agents.