NMR assignments of the C-terminal domain of human galectin-8

Galectins recognize β-galectosides to promote a variety of cellular functions. Despite their sequence variations, all galectins share the same carbohydrate recognition domains (CRD) and their modes of ligand recognition at a structural level are essentially identical. Human galectin 8 plays an important role in numerous cancer and immune responses. It consists of two CRDs that are connected via a flexible linker. The substrate affinities and specificities of the N- and C-terminal domains are quite different. In order to investigate the structural basis of their substrate specificities, we complete the NMR ¹H, ¹³C, and ¹⁵N chemical shift assignments of C-terminal domain of human galectin-8 (hG8C).     

Anti-apoptotic protein BRE/BRCC45 attenuates apoptosis through maintaining the expression of caspase inhibitor XIAP in mouse Lewis lung carcinoma D122 cells

Brain and Reproductive Organ Expressed (BRE), or BRCC45, is a death receptor-associated antiapoptotic protein, which is also involved in DNA-damage repair, and K63-specific deubiquitination. BRE overexpression attenuates both death receptor- and stress-induced apoptosis, promotes experimental tumor growth, and is associated with human hepatocellular and esophageal carcinoma. How BRE mediates its antiapoptotic function is unknown. Here we report based on the use of a mouse Lewis lung carcinoma cell line D122 that BRE has an essential role in maintaining the cellular protein level of XIAP, which is the most potent endogenous inhibitor of the caspases functioning in both extrinsic and intrinsic apoptosis. shRNA-mediated exhaustive depletion of BRE sensitized D122 cells to apoptosis induced not only by etopoxide, but also by TNF-α even in the absence of cycloheximide, which blocks the synthesis of antiapoptotic proteins by TNF-α-activated NF-κB pathway. In BRE-depleted cells, protein level of XIAP was downregulated, but not the levels of other antiapoptotic proteins, cIAP-1, 2, and cFLIP, regulated by the same NF-κB pathway. Reconstitution of BRE restored XIAP levels and increased resistance to apoptosis. XIAP mRNA level was also reduced in the BRE-depleted cells, but the level of reduction was less profound than that of the protein level. However, BRE could not delay protein turnover of XIAP. Depletion of BRE also increased tumor cell apoptosis, and decreased both local and metastatic tumor growth. Taken together, these findings indicate that BRE and its XIAP-sustaining mechanism could represent novel targets for anti-cancer therapy.     

Population-Based 5-Year Follow-Up Study in Taiwan of Dementia and Risk of Stroke

Background

This study estimates the risk of stroke within 5 years of newly diagnosed dementia among elderly persons aged 65 and above. We examined the relationship between antipsychotic usage and development of stroke in patients with dementia.

Methods

We conducted a nationwide 5-year population-based study using data retrieved from the Longitudinal Health Insurance Database 2005 (LHID2005) in Taiwan. The study cohort comprised 2243 patients with dementia aged ≥65 years who had at least one inpatient service claim or at least 2 ambulatory care claims, whereas the comparison cohort consisted of 6714 randomly selected subjects (3 for every dementia patient) and were matched with the study group according to sex, age, and index year. We further classified dementia patients into 2 groups based on their history of antipsychotic usage. A total of 1450 patients were classified into the antipsychotic usage group and the remaining 793 patients were classified into the non-antipsychotic usage group. Cox proportional-hazards regressions were performed to compute the 5-year stroke-free survival rates after adjusting for potentially confounding factors.

Results

The dementia patients have a 2-fold greater risk of developing stroke within 5 years of diagnosis compared to non-dementia age- and sex-matched subjects, after adjusting for other risk factors (95% confidence interval (CI) = 2.58–3.08; P<.001). Antipsychotic usage among patients with dementia increases risk of stroke 1.17-fold compared to patients without antipsychotic treatment (95% CI = 1.01–1.40; P<.05).

Conclusions

Dementia may be an independent risk factor for stroke, and the use of antipsychotics may further increase the risk of stroke in dementia patients.     

Structure and mechanism of Helicobacter pylori fucosyltransferase. A basis for lipopolysaccharide variation and inhibitor design

Helicobacter pylori alpha1,3-fucosyltransferase (FucT) is involved in catalysis to produce the Lewis x trisaccharide, the major component of the bacteria's lipopolysaccharides, which has been suggested to mimic the surface sugars in gastric epithelium to escape host immune surveillance. We report here three x-ray crystal structures of FucT, including the FucT.GDP-fucose and FucT.GDP complexes. The protein structure is typical of the glycosyltransferase-B family despite little sequence homology. We identified a number of catalytically important residues, including Glu-95, which serves as the general base, and Glu-249, which stabilizes the developing oxonium ion during catalysis. The residues Arg-195, Tyr-246, Glu-249, and Lys-250 serve to interact with the donor substrate, GDP-fucose. Variations in the protein and ligand conformations, as well as a possible FucT dimer, were also observed. We propose a catalytic mechanism and a model of polysaccharide binding not only to explain the observed variations in H. pylori lipopolysaccharides, but also to facilitate the development of potent inhibitors.     

Hydrolysis, lactonization, and identification of alpha(2 --> 8)/alpha(2 --> 9) alternatively linked tri-, tetra-, and polysialic acids

Alpha-(2 --> 8)/alpha(2 --> 9) alternatively linked polysialic acid (PSA) can be identified by controlled hydrolysis followed by the analysis with capillary electrophoresis (CE). Due to the different stability of alpha(2 --> 8) and alpha(2 --> 9) linkages in acidic hydrolysis, oligosialic acids (OSAs) from the hydrolysis of alpha(2 --> 8)/alpha(2 --> 9) OSA/PSA could be classified into two groups in the CE profile. The group with an odd numerical degree of polymerization (DP) had two peaks in the CE profile, and the other group, with even number of DP, showed one peak. Each alternating alpha(2 --> 8)/alpha(2 --> 9) linked OSA contains two isomers: one starts with the alpha(2 --> 8) linkage from the nonreducing end and the other starts with the alpha(2 --> 9) linkage from the nonreducing end. Trimers and tetramers were isolated by using a Mono Q column with an HPLC system. The two trimer isomers are alpha(2 --> 8)/alpha(2 --> 9) and alpha(2 --> 9)/alpha(2 --> 8) linkages and only showed partial separation by CE. After lactonization, sialidase hydrolysis, and alkaline treatment, the two trimer isomers could be separated and identified by CE analysis, but only the alpha(2 --> 8)/alpha(2 --> 9) trimer could be converted to the dilactone in glacial acetic acid. The two tetramer isomers could be converted to four monolactones and three dilactones. These lactonized species could be identified on the basis of several principles in sialidase hydrolysis and lactonization. In conclusion, regioselectivity on the lactonization of oligosialic acids proceeds under several principles: (1) Lactonization takes place more easily in the alpha(2 --> 8) linkage than in the alpha(2 --> 9) linkage; (2) all of the positions of alpha(2 --> 8) linkages in alpha(2 --> 8)/alpha(2 --> 9) alternatively linked OSA can be lactonized regardless of external or internal carboxyl groups involved; and (3) for the site of alpha(2 --> 9) linkage, only internal carboxyl groups can be lactonized.     

Effect of nitrite on interaction between the giant freshwater prawn Macrobrachium rosenbergii and its pathogen Lactococcus garvieae

Addition of nitrite-N at 1.5 mg l(-1) in tryptic soy broth (TSB) significantly (p < 0.05) decreased the growth rate of the bacterial pathogen Lactococcus garvieae and significantly (p < 0.05) reduced mortality compared to zero nitrite controls when injected into giant freshwater prawns Macrobrachium rosenbergii at 5 x 10(5) colony-forming units (CFU) per prawn. In other experiments, whereby prawns were injected with TSB-grown L. garvieae (5 x 10(5) CFU prawn(-1)) and then held in water containing nitrite-N, mortality at 72 h post-injection was significantly (p < 0.05) higher for prawns held in water containing 1.68 mg l(-1) nitrite than at lower concentrations. Prawns exposed to different concentrations of nitrite-N were examined for THC (total hemocyte count), phenoloxidase activity, respiratory burst, phagocytic activity and bacterial clearance efficiency. No significant differences in THC and phenoloxidase activity were observed among treatments. With prawns exposed to nitrite-N for 168 h (7 d) at 1.59 mg l(-1), phagocytic activity and clearance efficiency decreased, while at 1.15 mg l(-1) or more, respiratory burst increased, generating the superoxide anion at levels considered cytoxic to the host. We conclude that nitrite-N at 1.68 mg l(-1) causes depression in the immune response and increased mortality in M. rosenbergii infected with L. garvieae.     

Enhancement of immunity and disease resistance in the white shrimp,Litopenaeus vannamei,by the probiotic,Bacillus subtilis E20

Effects of Bacillus subtilis E20 isolated from fermented soybean on immune parameters and the disease resistance of the white shrimp (Litopenaeus vannamei) after 98 days of B. subtilis E20 feeding were evaluated in this study. Shrimp fed B. subtilis E20-containing diets at concentrations of 10⁶ (E206), 10⁷ (E207), and 10⁸ (E208) cfu kg^?1, respectively, had significantly increased survival rates of 13.3%, 16.7%, and 20%, compared to the control (fed no probiotic) after being challenged with Vibrio alginolyticus. There were no significant differences in the total hemocyte count, respiratory burst, or superoxide dismutase glutathione peroxidase among all treatments. Shrimp fed a higher concentration of the probiotic (E208) exhibited significant increases in phenoloxidase activity, phagocytic activity, and clearance efficiency compared to control shrimp. In addition, B. subtilis E20 showed a weaker inhibitory effect against the growth of Aeromona hydrophila with around a 0.3-cm inhibitory zone, but showed no inhibitory effects against other selected pathogens, such as white shrimp pathogens: V. alginolyticus and Vibrio vulnificus. These results suggest that the increased resistance of shrimp after B. subtilis E20 consumption occurs through immune modifications, such as increases in phenoloxidase activity, phagocytic activity, and clearance efficiency against V. alginolyticus.     

Fracture Risk and Adjuvant Therapies in Young Breast Cancer Patients: A Population-Based Study

Background

Breast cancer survivors have an increased risk of bone fracture. But the risk among young patients with adjuvant therapies remains unknown. This population-based study is aimed to assess the incidence and risk of fracture among young (age of 20 to 39 years) breast cancer patients who received adjuvant therapies.

Methods

From January 2001 to December 2007, 5,146 newly diagnosed breast cancer patients were enrolled from the National Health Insurance Research Database (NHIRD) in Taiwan. Patients were observed for a maximum of 6 years to determine the incidence of newly onset fracture. Kaplan Meier and Cox regression analyses were used to evaluate the risk of fracture in young breast cancer patients who received adjuvant treatments.

Results

Of the total 5,146 young (age of 20 to 39 years) breast cancer patients, the Cox multivariate proportional hazards analysis showed that AIs, radiotherapy, and monoclonal antibodies were significantly associated with a high risk of fracture. Moreover, patients who received AIs for more than 180 days had a high hazard ratio (HR) of 1.77 (95% CI = 0.68–4.57), and patients who received more than four radiotherapy visits had a high HR of 2.54 (95% CI = 1.07–6.06). Under the site-specific analysis, young breast cancer patients who received AIs had the highest risk of hip fracture (HR = 8.520, 95% CI = 1.711–42.432, p < 0.04), whereas patients who received radiotherapy had the highest risk of vertebral fracture (HR = 5.512, 95% CI = 1.847–16.451, p < 0.01).

Conclusion

Young breast cancer patients who are receiving AIs, radiotherapy or monoclonal antibody need to be more careful for preventing fracture events. Breast cancer treatment plans are suggested to incorporate fracture prevention interventions.     

Effects of the probiotic,Bacillus subtilis E20, on the survival,development, stress tolerance,and immune status of white shrimp,Litopenaeus vannamei larvae

In this study, the probiotic, Bacillus subtilis E20, isolated from the human health food, natto, was used for white shrimp, Litopenaeus vannamei, larvae breeding to improve the larval survival rate and development by adding probiotic to the rearing water at (control), 10⁸, and 10⁹ cfu L^?1 salt water once every 3 days during the 14 days of breeding experiment. Thereafter, stress tolerance and immune status of postlarvae were evaluated. Shrimp larval development was significantly accelerated after adding the probiotic to the larval rearing water at a level of 10⁹ cfu L^?1. The survival rate of larvae was significantly higher in the treatment with 10⁹ cfu L^?1 compared to the control and the treatment with 10⁸ cfu L^?1 after all larvae had metamorphosed to postlarvae. Adding the probiotic to the shrimp larvae rearing water produced a weak inhibition of bacterial growth by an analysis of the total bacterial count and presumptive Vibrio count. For stress tests, no postlarvae died when they were reared in water in which the temperature was decreased from 30 to 2 °C at a rate of 0.1 °C min^?1. Postlarvae had significantly lower cumulate mortality in the treatments with 10⁸ and 10⁹ cfu L^?1 compared to the control when they were suddenly exposed to fresh water and 60‰ salt water. A significant decrease in the cumulative mortality of postlarvae treated with the probiotic at a level of 10⁹ cfu L^?1 was recorded after the sudden transfer to 300 mg L^?1 nitrite-N compared to the control and treatment with 10⁸ cfu L^?1. The analysis of immune-related gene expressions showed that the gene expression of prophenoloxidase I, prophenoloxidase II, and lysozyme of larvae were significantly increased after being reared in probiotic-containing water at the levels of 10⁸ and 10⁹ cfu L^?1. However, no significant difference in serine proteinase or glutathione peroxidase gene expressions was recorded in this study. It is therefore suggested that 10⁹ cfu L^?1 of probiotic, B. subtilis E20 adding to rearing water for shrimp larva breeding.