Selection pressure on the hemagglutinin gene of influenza A (H1N1) virus: adaptation to human and swine hosts in Asia

Influenza A (H1N1) virus is an important pathogen that can be transmitted in the enzootic cycle involved in influenza epidemics. In this study, we analyzed natural selection on the 260 sequences of subtype 1 hemagglutinin (HA1) gene of H1N1 viruses isolated from humans and swine in Asia. Nonsynonymous and synonymous substitution rates (dN, dS) were determined for each amino acid site in the HA1 coding region. Four and two positively selected sites were identified in human and swine viruses, respectively. These sites might be involved in the change of antigenic epitopes to evade the host immune system. The results indicate that more diversifying and less purifying selection controls HA1 of human viruses compared with the swine viruses. Furthermore, thirteen sites evolving differently in human and swine viruses were identified in the HA1. These sites may play a role in the cross-species transmission. The analysis of adaptive evolution of the HA1 can provide valuable information for accelerating vaccine and drug development for prevention and treatment of influenza A (H1N1) in Asia.

KEYWORDS

Influenza A virus; H1N1; hemagglutinin; positive selection; antigenic epitope.

Prenatal ethanol exposure attenuates GABAergic inhibition in basolateral amygdala leading to neuronal hyperexcitability and anxiety-like behavior of adult rat offspring

Prenatal exposure to a relatively high-dose ethanol (EtOH) caused anxiety-like behavior of adult male rat offspring. Previous studies have demonstrated that GABA system in the basolateral amygdala complex (BLA) is involved in the pathogensis of anxiety-related disorders. The role of GABAergic system in the BLA was investigated in anxiety-like behavior evoked by prenatal EtOH exposure. The infusion of midazolam (MDZ), a positive modulator of GABA(A) receptor, into the BLA prevented anxiety-like behavior in EtOH-offspring without affecting the corresponding behavior of control offspring. The data suggest that anxiety-like behavior could be causally related to increased neuronal excitability attributable to depressed GABAergic inhibition in the BLA. To test this hypothesis, evoked potential was studied using brain slices from EtOH-offspring. Potential evoked in the BLA by single stimuli applied to external capsule showed multispike responses, indicative of GABAergic disinhibition. These multiple responses were no longer evident after the perfusion with MDZ. In the slices from EtOH-offspring, paired-pulse inhibition (GABA(A)-dependent) was suppressed. Also, in EtOH-offspring, long-term potentiation (LTP) was induced by a single train of high frequency stimulation, which did not induce LTP in control rats. Moreover, MDZ pretreatment prevented the facilitating effect of EtOH on LTP induction. The data provide the functional evidence that prenatal EtOH exposure attenuates GABAergic inhibition in the BLA resulting in neuronal hyperexcitability and anxiety-like behavior of adult rat offspring.

Evaluation of aldehyde dehydrogenase 1 (ALDH1) as a marker of non-small cell lung cancer (NSCLC) stem cells (SCs) and correlation with prognosis

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Background: ALDH1 is a cytosolic enzyme responsible for oxidizing intracellular aldehydes, and conversion of retinol to retinoic acid in SCs. ALDH1 has been previously demonstrated to be a marker for SCs in breast cancer (Ginestier C, et al., Cell Stem Cell. 2007 Nov; 1(5):555–67). The Aldefluor assay is based on conversion of a synthetic substrate BAAA, when passively infused into cytosol, to brightly fluorescent BAA by ALDH1. Combined with fluorescence-activated cell sorting (FACS), it has been used successfully in hematopoietic and breast cancer SCs isolation. ALDH1 is also found in NSCLC. We hypothesized that ALDH1 would be a marker for NSCLC SCs and a potential prognostic marker. Methods: NSCLC SCs were isolated from human NSCLC cell lines using the Aldefluor assay and FACS. ALDH1-positive cells were analyzed extensively for SC characteristics. ALDH1 expression in 303 NSCLC biopsy specimens from three independent cohorts of NSCLC patients was then analyzed by immunohistochemisty (IHC) using an ALDH1 antibody (Santa Cruz Biotechnology) and commercially available negative controls. Results: Isolated cancer cells with high ALDH1 activity displayed cancer SCs features, including capacities for proliferation, self-renewal, differentiation; resistance to chemotherapeutic agents including cisplatin, vinorelbine, gemcitabine and docetaxel; expression of the SC surface marker CD133, and high invasiveness. ALDH1-positive cells generated tumors in vivo recapitulating heterogeneity of parental cells. Xenograft tumors derived from ALDH1-positive cells (103 each) were 36±2.9 mm3 on average in size, with some of the cells having lost ALDH1 expression. Xenograft tumors derived from ALDH1-negative cells (105 each) were 4 mm3 on average in size, without ALDH1 reactivation. Statistical analysis of quantitative IHC and clinical data showed ALDH1 expression was correlated with higher stage and grade of NSCLC (p = 0.02). Expression of ALDH1 in stage I NSCLC patients was linked to decreased 5 year cancer-specific survival (62% vs. 96%, p = 0.006) and overall survival (32% vs. 72%, p = 0.009). Conclusions: 1. ALDH1 is a NSCLC SC-associated tumor marker. 2. ALDH1 expression is a negative prognostic marker in early stage NSCLC.

No significant financial relationships to disclose.

The impact of obesity on adherence to the National Comprehensive Cancer Network (NCCN) guidelines recommending chemotherapy for patients with operable breast cancer

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Background: Obesity (measured using body mass index [BMI]) is regarded as a prognostic factor for worse breast cancer survival. We hypothesized that obesity may influence adherence to NCCN guidelines recommending chemotherapy for patients with operable breast cancer at NCCN centers. Methods: We identified women < 70 years diagnosed with stage I, II, or III breast cancer from 1997 to 2006 at 8 NCCN centers for whom guidelines recommended chemotherapy. Body mass index was assessed in categories (<25 kg/m2 [normal], 25 to <30 kg/m2 [overweight], 30 to 39kg/m2 [obese], ≥40 kg/m2 [morbidly obese]) and in 5 kg/m2 increments. Multivariable logistic regression analysis adjusting for center, age at diagnosis, ethnicity, comorbidity score, and guideline was used to examine the association between BMI at diagnosis and non-receipt of chemotherapy. Results: 9,389 women were eligible for the study: 38% normal weight; 30% overweight; 23% obese; 5% morbidly obese; and 4% unknown. In multivariable analysis with BMI as a categorical variable, there was no association between weight status and non-receipt of chemotherapy (p = 0.35). When BMI was assessed in 5kg/m2 increments, weight status was a statistically significant predictor of non-receipt of chemotherapy (p = 0.02), but the odd ratios exceeded 1.0 only for BMIs ≥42.6kg/m2. Other patient-related factors associated with non-receipt of chemotherapy included older age at diagnosis (p < 0.01), presence of comorbidities (p < 0.01) and center (p < 0.01). Conclusions: Overall, the quality of breast cancer care as measured by adherence to NCCN guidelines recommending chemotherapy was not affected by patient overweight or obese status. Chemotherapy use was lower among patients with extreme morbid obesity, which may represent appropriate clinical decision-making. Evaluating factors that may contribute to worse prognosis among obese patients is essential for individualizing care and improving breast cancer outcome.

No significant financial relationships to disclose.

PCR specific for Actinobacillus pleuropneumoniae serotype 3

Serotypes 3 and 8 of Actinobacillus pleuropneumoniae, the aetiological agent of porcine pleuropneumonia, have been reported to predominate in the UK. Direct serotyping of isolates of the organism is typically determined by the immunological reactivity of rabbit serum to its surface polysaccharides, but the method has limitations, for example, cross-reactions between serotypes 3, 6 and 8. This study describes the development of a serotype 3-specific pcr, based on the capsule locus, which can be used in a multiplex format with the organism's specific gene apxIV. The pcr test was evaluated on 266 strains of A pleuropneumoniae and 121 strains of other organisms, including all the major respiratory bacterial pathogens of pigs. The test was highly specific and sensitive and should be useful for differentiating strains of serotypes 3, 6 and 8, and in seroprevalence and epidemiological surveys in regions where serotype 3 is prevalent, such as the UK.

The new water-soluble artemisinin derivative SM905 ameliorates collagen-induced arthritis by suppression of inflammatory and Th17 responses

BACKGROUND AND PURPOSE

Our previous study showed that SM905, a novel artemisinin derivative, exhibited potent immunosuppressive activity. In this study, we evaluate preventive and therapeutic effect of SM905 on collagen-induced arthritis (CIA) in DBA/1 mice, and investigate its mechanisms both in inflammatory and autoimmune aspects of the disease.

EXPERIMENTAL APPROACH

CIA was induced by type II bovine collagen (CII) in DBA/1 mice. SM905 was given orally either before (continuously 1 day before booster immunization) or after disease onset (continuously 14 days after booster immunization). Disease incidence and severity were monitored, mRNA expression of proinflammatory mediators was determined by real-time PCR, purified T cell proliferation was assessed using [(3)H]-thymidine incorporated assay, and T helper (Th) 17/Th1/Th2 type cytokine production was examined by ELISA.

KEY RESULTS

Oral treatment with SM905 delayed disease onset, reduced arthritis incidence and severity, and suppressed the enhanced expression of pro-inflammatory cytokines, chemokines and chemokine receptors in draining lymph nodes. The CII-induced T cell proliferation and production of interleukin (IL)-17A by T cells were strikingly inhibited. Correspondingly, the mRNA expression of IL-17A and RORgamma t (a specific transcription factor for Th17) was also reduced. This effect was coupled with a striking reduction of IL-6 production, which has a critical role in Th17 development. In established arthritis, SM905 profoundly inhibited disease progression, reduced IL-17A and RORgamma t mRNA expression, and suppressed pro-inflammatory mediator expression in arthritic joints.

CONCLUSIONS AND IMPLICATIONS

SM905 had beneficial effects on CIA by suppressing inflammatory and pathogenic Th17 responses.

Multiplex PCR that can distinguish between immunologically cross- reactive serovar 3, 6, and 8 Actinobacillus pleuropneumoniae strains

We describe a highly sensitive and specific multiplex PCR, based on capsular loci and the species specific apxIV gene, that unequivocally differentiates serovar 3, 6, and 8 Actinobacillus pleuropneumoniae strains that are cross-reactive in conventional immunological tests.

Genetic and QTL analysis of resistance to Xiphinema index in a grapevine cross

Resistance to the dagger nematode Xiphinema index has been an important objective in grape rootstock breeding programs. This nematode not only causes severe feeding damage to the root system, but it also vectors grapevine fanleaf virus (GFLV), the causal agent of fanleaf degeneration and one of the most severe viral diseases of grape. The established screening procedures for dagger nematode resistance are time consuming and can produce inconsistent results. A fast and reliable greenhouse-based system for screening resistance to X. index that is suitable for genetic studies and capable of evaluating breeding populations is needed. In this report, the dynamics of nematode numbers, gall formation, and root weight loss were investigated using a variety of soil mixes and pot sizes over a 52-week period. Results indicated that the number of galls formed was correlated with the size of the nematode population and with the degree of root weight loss. After inoculation with 100 nematodes, gall formation could be reliably evaluated in 4-8 weeks in most plant growth conditions and results were obtained 6 months more rapidly than past evaluation methods. This modified X. index resistance screening method was successfully applied to 185 of the 188 F(1) progeny from a cross of D8909-15 x F8909-17 (the 9621 population), which segregates for a form of X. index resistance originally derived from Vitis arizonica. Quantitative trait loci (QTL) analysis was carried out on both parental genetic maps of 255 markers using MapQTL 4.0. Results revealed that X. index resistance is controlled by a major QTL, designated Xiphinema index Resistance 1 (XiR1), near marker VMC5a10 on chromosome 19. The XiR1 QTL was supported by a LOD score of 36.9 and explained 59.9% of the resistance variance in the mapping population.

Anytime Heuristic Search

We describe how to convert the heuristic search algorithm A* into an anytime algorithm that finds a sequence of improved solutions and eventually converges to an optimal solution. The approach we adopt uses weighted heuristic search to find an approximate solution quickly, and then continues the weighted search to find improved solutions as well as to improve a bound on the suboptimality of the current solution. When the time available to solve a search problem is limited or uncertain, this creates an anytime heuristic search algorithm that allows a flexible tradeoff between search time and solution quality. We analyze the properties of the resulting Anytime A* algorithm, and consider its performance in three domains; sliding-tile puzzles, STRIPS planning, and multiple sequence alignment. To illustrate the generality of this approach, we also describe how to transform the memory-efficient search algorithm Recursive Best-First Search (RBFS) into an anytime algorithm.

Investigation of the immunosuppressive activity of artemether on T-cell activation and proliferation

BACKGROUND AND PURPOSE

Artemisinin and its derivatives exhibit potent immunosuppressive activity. The purpose of the current study was to examine the immunosuppressive activity of artemether directly on T lymphocytes and to explore its potential mode of action.

EXPERIMENTAL APPROACH

In vitro, T-cell proliferation was measured using [(3)H]-thymidine incorporation assay in cells stimulated with ConA, alloantigen and anti-CD3 antibody. CFSE-labeled cell division and cell cycle distribution were monitored by flow cytometry. In vivo, the effects of artemether were evaluated in delayed-type hypersensitivity (DTH) and purified T-cell responses to ovalbumin in ovalbumin-immunized mice. The activation of extracellular signal-regulated kinase1/2 (ERK1/2) and Raf1 were assessed by Western blot analysis and the activation of Ras was tested in pull-down assays.

KEY RESULTS

We show that, in vitro, artemether suppressed ConA- or alloantigen-induced splenocyte proliferation, influenced production of the cytokines IL-2 and IFN-gamma and inhibited cell cycle progression through the G0/G1 transition. In vivo, administration of artemether attenuated CD4 T-cell-mediated DTH reaction, and suppressed antigen-specific T-cell response in immunized mice. Further experiments showed that, treatment with artemether impaired both antigen- and anti-CD3-induced phosphorylation of ERK. In primary T cells, artemether profoundly inhibited anti-CD3-induced phosphorylation of Raf1 and activation of Ras.

CONCLUSIONS AND IMPLICATIONS

This study provided experimental evidence of the immunosuppressive effects of artemether directly on T cells both in vitro and in vivo. Its immunosuppressive mechanism involved inhibition of the activation of the Ras-Raf1-ERK1/2 protein kinase cascade in T cells.

T1-weighted cine FLASH is superior to IR imaging of post-infarction myocardial viability at 4.7T

PURPOSE

Data are unavailable for rational selection of pulse sequences to assess postinfarction myocardial viability in rodents at high field strength. We implemented a widely used clinical inversion recovery (IR) sequence at 4.7T and compared the results to a heavily T1-weighted cine FLASH sequence (T1-CF) for assessment of infarction size.

MATERIALS AND METHODS

Eleven infarcted rats were examined within 24 h of infarction after injection of Gadophrin-3 contrast agent. Images were acquired using both pulse sequences and a standard cine (SC) sequence. Estimates of infarct size were compared to TTC. Global LV function was compared between the T1-CF and SC sequences.

RESULTS

SNR, relative SNR, and CNR for the infarcted and normal myocardium were significantly greater for the IR sequence. Infarction size was overestimated by both sequences, but correlated highly and showed very close agreement with TTC. Global function revealed no significant differences between T1-CF and SC.

CONCLUSION

Both IR and T1-CF produced reliable results for assessment of infarction size at 4.7T. While the IR sequence delivers better overall SNR and CNR, the T1-CF allows concomitant assessment of global cardiac function with a much shorter acquisition time.

Non-lethal freezing effects on seed degreening in Brassica napus

The effects of a non-lethal freezing stress on chlorophyll content, moisture level and distribution, and abscisic acid (ABA) levels were examined in siliques and seeds of Brassica napus (canola). A non-lethal freezing stress resulted in the retention of chlorophyll in seed at harvest that was most pronounced for seeds 28, 32 and 36 days after flowering (DAF). This increase was primarily due to an increased retention of chlorophyll a relative to chlorophyll b. Chlorophyll retention in seeds exposed to a non-lethal freezing stress correlated with an increased ABA catabolism, as measured 1, 3 or 7 days after the stress treatment. Although the non-lethal freezing stress had no significant effect on moisture content in seeds of siliques stressed at 28-44 DAF, moisture distribution, as viewed by magnetic resonance imaging, showed an uneven drying of 32 and 40 DAF siliques after exposure to the non-lethal freezing stress. Moisture was initially lost more rapidly from the silique wall between seeds, than in control non-stressed siliques. Increased moisture loss was not due to structural changes in the vasculature of the silique/seed of stressed tissues. These results are consistent with the hypothesis that a non-lethal freezing stress-induced decrease in ABA level, during seed maturation, effects an inhibition of normal chlorophyll a catabolism resulting in mature but green B. napus seed.