P22-Mediated Transduction Analysis of the Rough A (rfa) Region of the Chromosome of Salmonella typhimurium

Seven temperature-sensitive rough mutants of Salmonella typhimurium were found to be sensitive to smooth-specific phages at low temperature (25 C, 30 C) and resistant or partially resistant to rough-specific phages, whereas at high temperatures (37 C, 45 C) they were resistant or partially resistant to smooth-specific phages but sensitive to rough-specific phages. These data indicate that at low temperature each strain makes lipopolysaccharide which is relatively normal, but at high temperatures O-specific side chains are not added to the lipopolysaccharide. At 45 C, these strains have the R-res-1 or R-res-2 phage sensitivity phenotype, and their genetic lesions map by P22-mediated transduction in the rfa gene cluster between cysE-pyrE, suggesting a mutation in genes with transferase functions. P22-mediated joint transduction with temperature-sensitive rfa mutants, leaky rfa mutants, and rfa P22 lysogens have shown the following order of genes in the S. typhimurium linkage map: xyl-mtlA-mtlB-cysE-rfaF-rfaG-pyrE. An rfaE allele was not jointly transduced in the cysE-pyrE segment.     

Simultaneous immunohistochemical detection of IUdR and BrdU infused intravenously to cancer patients

Cell cycle kinetics of solid tumors in the past have been restricted to an in vitro labeling index (LI) measurement. Two thymidine analogues, bromodeoxyuridine (BrdU) and iododeoxyuridine (IUdR), can be used to label S-phase cells in vivo because they can be detected in situ by use of monoclonal antibodies (MAb) against BrdU (Br-3) or IUdR (3D9). Patients with a variety of solid tumors (lymphoma, brain, colon cancers) received sequential intravenous IUdR and BrdU. Tumor tissue removed at the end of infusion was embedded in plastic and treated with MAb Br-3 and 3D9 sequentially, using a modification of a previously described method. Clearly single and double labeled cells were visible, which enabled us to determine the duration of S-phase (Ts) and the total cell cycle time (Tc), in addition to the LI in these tumors. Detailed control experiments using tissue culture cell lines as well as bone marrow cells from leukemic patients are described, including the comparison of this double label technique with our previously described BrdU-tritiated thymidine technique. We conclude that the two methods are comparable and that the IUdR/BrdU method permits rapid and reliable cell cycle measurements in solid tumors.     

Unravelling the Carbon and Sulphur Metabolism in Coastal Soil Ecosystems Using Comparative Cultivation-Independent Genome-Level Characterisation of Microbial Communities

Bacterial autotrophy contributes significantly to the overall carbon balance, which stabilises atmospheric CO₂ concentration and decelerates global warming. Little attention has been paid to different modes of carbon/sulphur metabolism mediated by autotrophic bacterial communities in terrestrial soil ecosystems. We studied these pathways by analysing the distribution and abundance of the diagnostic metabolic marker genes cbbM, apsA and soxB, which encode for ribulose-1,5-bisphosphate carboxylase/oxygenase, adenosine phosphosulphate reductase and sulphate thiohydrolase, respectively, among different contrasting soil types. Additionally, the abundance of community members was assessed by quantifying the gene copy numbers for 16S rRNA, cbbL, cbbM, apsA and soxB. Distinct compositional differences were observed among the clone libraries, which revealed a dominance of phylotypes associated with carbon and sulphur cycling, such as Gammaproteobacteria (Thiohalomonas, Allochromatium, Chromatium, Thiomicrospira) and Alphaproteobacteria (Rhodopseudomonas, Rhodovulum, Paracoccus). The rhizosphere soil was devoid of sulphur metabolism, as the soxB and apsA genes were not observed in the rhizosphere metagenome, which suggests the absence or inadequate representation of sulphur-oxidising bacteria. We hypothesise that the novel Gammaproteobacteria sulphur oxidisers might be actively involved in sulphur oxidation and inorganic carbon fixation, particularly in barren saline soil ecosystems, suggesting their significant putative ecological role and contribution to the soil carbon pool.     

siRNA against presenilin 1 (PS1) down regulates amyloid β42 production in IMR-32 cells

Background  

One of the pathological hallmarks of Alzheimer's disease (AD) is the deposition of the ~4 kDa amyloid β protein (Aβ) within lesions known as senile plaques. Aβ is also deposited in the walls of cerebral blood vessels in many cases of AD. A substantial proportion of the Aβ that accumulates in the AD brain is deposited as Amyloid, which is highly insoluble, proteinaceous material with a β-pleated-sheet conformation and deposited extracellularly in the form of 5-10 nm wide straight fibrils. As γ-secretase catalyzes the final cleavage that releases the Aβ42 or 40 from amyloid β -protein precursor (APP), therefore, it is a potential therapeutic target for the treatment of AD. γ-Secretase cleavage is performed by a high molecular weight protein complex containing presenilins (PSs), nicastrin, Aph-1 and Pen-2. Previous studies have demonstrated that the presenilins (PS1 and PS2) are critical components of a large enzyme complex that performs γ-secretase cleavage.     

Selenium protects cerebral ischemia in rat brain mitochondria

Normal cellular metabolism produces oxidants that are neutralized by the cells' antioxidant enzymes and antioxidants taken from outside. An imbalance between oxidant and antioxidant has been postulated to lead to the neurodegeneration in the ischemic condition. In this study, we have demonstrated the prevention or slowdown of neuronal injury in middle cerebral artery occlusion (MCAO) by sodium selenite. Rats were pretreated with 0.05, 0.1, and 0.2 mg/kg body wt of sodium selenite for 7 d. The rats of group I (sham) and group II (ischemia) were pretreated with physiological saline for 7 d. On d 8, MCAO was induced for 2 h in, the right side of brain of group II, III, IV, and V rats. Brains were dissect out after 22 h of reperfusion and washed with chilled physiological saline. The right cerebral hemisphere was used for the preparation of mitochondria. The activity of superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, and monoamine oxidase (MAO-A and MAO-B) was depleted significantly; conversely, the activity of poly(ADP-ribosyl) polymerase was elevated significantly as compared to the sham, and the pretreatment of the animals with different doses of sodium selenite has protected the activity of these enzymes significantly. The content of glutathione was decreased significantly, whereas the level of lipid peroxidation was increased significantly in the mitochondria of MCAO as compared to the sham group, and pretreatment with different doses of sodium selenite has protected their levels significantly as compared to the MCAO group. It is concluded that selenium, which is an essential part of our diet, might be helpful in protection against neurodegeneration in cerebral ischemia.     

Ginkgo biloba affords dose-dependent protection against 6-hydroxydopamine-induced parkinsonism in rats: neurobehavioural, neurochemical and immunohistochemical evidences

Ginkgo biloba extract (EGb), a potent antioxidant and monoamine oxidase B (MAO-B) inhibitor, was evaluated for its anti-parkinsonian effects in a 6-hydroxydopamine (6-OHDA) rat model of the disease. Rats were treated with 50, 100, and 150 mg/kg EGb for 3 weeks. On day 21, 2 microL 6-OHDA (10 microg in 0.1% ascorbic acid saline) was injected into the right striatum, while the sham-operated group received 2 microL of vehicle. Three weeks after 6-OHDA injection, rats were tested for rotational behaviour, locomotor activity, and muscular coordination. After 6 weeks, they were killed to estimate the generation of thiobarbituric acid reactive substances (TBARS) and reduced glutathione (GSH) content, to measure activities of glutathione-S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), catalase, and superoxide dismutase (SOD), and to quantify catecholamines, dopamine (DA) D2 receptor binding, and tyrosine hydroxylase-immunoreactive (TH-IR) fibre density. The increase in drug-induced rotations and deficits in locomotor activity and muscular coordination due to 6-OHDA injections were significantly and dose-dependently restored by EGb. The lesion was followed by an increased generation of TBARS and significant depletion of GSH content in substantia nigra, which was gradually restored with EGb treatment. EGb also dose-dependently restored the activities of glutathione-dependent enzymes, catalase, and SOD in striatum, which had reduced significantly by lesioning. A significant decrease in the level of DA and its metabolites and an increase in the number of dopaminergic D2 receptors in striatum were observed after 6-OHDA injection, both of which were significantly recovered following EGb treatment. Finally, all of these results were exhibited by an increase in the density of TH-IR fibers in the ipsilateral substantia nigra of the lesioned group following treatment with EGb; the lesioning had induced almost a complete loss of TH-IR fibers. Considering our behavioural studies, biochemical analysis, and immunohistochemical observation, we conclude that EGb can be used as a therapeutic approach to check the neuronal loss following parkinsonism.     

Progesterone inhibits the growth of human neuroblastoma: in vitro and in vivo evidence

We investigated the antitumorogenic effects of progesterone (P4) in a human neuroblastoma (SK-N-AS) cell line in vitro and in a mouse xenograft model of neuroblastoma. The safety of P4 was tested in rat primary cortical neurons and human foreskin fibroblasts (HFF-1). At high doses, P4 significantly (P < 0.05) decreased SK-N-AS cell viability in vitro, and this effect was not blocked either by 5α-reductase inhibitor, finasteride or the P4 receptor antagonist RU486. Even at very high doses, P4 did not induce any cell death in healthy primary cortical neurons or HFF-1. The bioavailability of P4 24 h after the last injection in the serum of treated animals was significantly (P < 0.05) higher (10-33 μg/mL) than in untreated animals. In nude mice, P4 (50 and 100 mg/kg) inhibited neuroblastoma growth by ~50% over 8 d of treatment. No drug toxicity was observed in the mice, as measured by body weight and activity. P4 suppressed the expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMP-9, MMP-2), which are involved in tumor vascular development. High-dose P4 inhibited tumor growth by suppressing cell proliferation and inducing apoptosis, as evidenced by the expression of proliferating cell nuclear antigen and cleaved caspase-3. P4 significantly increased the expression of P4 receptor isoform-A and suppressed phospho-Akt (Ser437) expression. In conclusion, at high doses, P4 effectively inhibits the growth of solid neuroblastoma tumor and has high bioavailability, selective toxicity and a high margin of safety, making it a possible candidate for further study as a potential clinical treatment of neuroblastoma.     

Ring A structural modified derivatives of withaferin A and the evaluation of their cytotoxic potential

Regio-/stereoselective Michael addition to ring A of withaferin-A was performed using an optimized reaction procedure to synthesise a library of 2,3-dihydro,3-β-substituted withaferin-A derivatives. The analogues thus obtained were evaluated for in vitro cytotoxicity against various human cancer cell lines. 3-Azido analogue exhibited 35-fold increase (IC(50)=0.02-1.9 μM) in cytotoxicity against almost the entire cell lines tested when compared to the parent molecule. However, further modifications of 3-azido analogue with various alkynes under Husigen's cycloaddition conditions generated a variety of triazole derivatives with reduced cytotoxicity.