Genetic variability in Puccinia striiformis f. sp. tritici populations sampled on a local scale during natural epidemics

This study investigated genetic polymorphism on a local scale in Puccinia striiformis f. sp. tritici populations during natural epidemics, in four fields located in northern France and sampled in 1998 or 1999. Two hundred and forty-seven isolates were analyzed for their amplified fragment length polymorphism (AFLP) pattern through four primer combinations, and 194 of them were also tested for their virulence factors. Only one or two pathotypes were found in each field, and all isolates had virulence v17, matching the recently introduced Yr17 resistance gene. Polymorphism on a field scale was low. Although 67 loci were polymorphic, 77% of the isolates had the same AFLP pattern, all other patterns being rare or unique. Analyses of the genetic distance between AFLP patterns based on the Jaccard index allowed us to define 12 groups, but a bootstrap analysis showed that all isolates could be assigned to a single clonal lineage. This leads us to conclude that P. striiformis f. sp. tritici populations are clonal on a field scale in northern France.     

c-Src mediates mitogenic signals and associates with cytoskeletal proteins upon vascular endothelial growth factor stimulation in Kaposi's sarcoma cells

Vascular endothelial growth factor (VEGF) appears to be a critical cytokine modulating the growth and spread of Kaposi's sarcoma (KS). Furthermore, infection with the KS herpes virus results in up-regulation of VEGF and triggering of VEGF receptor activation. The molecular mechanisms regulating such cytokine-driven proliferation of KS cells are not well characterized. We investigated the role of Src-related tyrosine kinases in VEGF-mediated signaling in model KS 38 tumor cells. VEGF stimulation specifically activated c-Src kinase activity but not that of other related Src kinases such as Lyn, Fyn, or Hck in KS cells. Pyrazolopyrimidine, a selective inhibitor of Src family tyrosine kinases, significantly blocked the VEGF-induced growth of KS cells. Further studies using mutants of c-Src kinase revealed that Src mediates mitogen-activated protein kinase activation induced by VEGF. We also observed that VEGF stimulation resulted in increased tyrosine phosphorylation of the focal adhesion components paxillin and p130cas. Furthermore, VEGF induction enhanced the complex formation between Src kinase and paxillin. Src kinase appears to play an important functional role in VEGF-induced signaling in KS cells and may act to link pathways from the VEGF receptor to mitogen-activated protein kinase and cytoskeletal components, thereby effecting tumor proliferation and migration.     

Beta-chemokine receptor CCR5 signals through SHP1, SHP2, and Syk

The beta-chemokine receptor CCR5 has been shown to modulate cell migration, proliferation, and immune functions and to serve as a co-receptor for the human immunodeficiency virus. We and others have shown that CCR5 activates related adhesion focal tyrosine kinase (RAFTK)/Pyk2/CAK-beta. In this study, we further characterize the signaling molecules activated by CCR5 upon binding to its cognate ligand, macrophage inflammatory protein-1beta (MIP1beta). We observed enhanced tyrosine phosphorylation of the phosphatases SHP1 and SHP2 upon MIP1beta stimulation of CCR5 L1.2 transfectants and T-cells derived from peripheral blood mononuclear cells. Furthermore, we observed that SHP1 associated with RAFTK. However, using a dominant-negative phosphatase-binding mutant of RAFTK (RAFTK(m906)), we found that RAFTK does not mediate SHP1 or SHP2 phosphorylation. SHP1 and SHP2 also associated with the adaptor protein Grb2 and the Src-related kinase Syk. Pretreatment of CCR5 L1.2 transfectants or T-cells with the phosphatase inhibitor orthovanadate markedly abolished MIP1beta-induced chemotaxis. Syk was also activated upon MIP1beta stimulation of CCR5 L1.2 transfectants or T-cells and associated with RAFTK. Overexpression of a dominant-negative Src-binding mutant of RAFTK (RAFTK(m402)) significantly attenuated Syk activation, whereas overexpression of wild-type RAFTK enhanced Syk activity, indicating that RAFTK acts upstream of CCR5-mediated Syk activation. Taken together, these results suggest that MIP1beta stimulation mediated by CCR5 induces the formation of a signaling complex consisting of RAFTK, Syk, SHP1, and Grb2.     

Helicobacter pylori,HIV and Gastric Hypochlorhydria in the Malawian Population

Background

HIV and Helicobacter pylori are common chronic infections in sub-Saharan Africa. Both conditions can predispose to gastric hypochlorhydria that may be a risk factor for enteric infections and reduced drug absorption. We have investigated to what extent HIV and H. pylori infections are associated with hypochlorhydria in a Malawian cohort of patients undergoing endoscopy.

Methods

104 sequential symptomatic adults referred for gastroscopy at Queen Elizabeth Central Hospital, Blantyre, Malawi, had blood taken for rapid HIV testing and fasting serum gastrin analysis. Gastric fluid was aspirated for pH testing, and gastric biopsies were taken.

Results

After 9/104 HIV-infected patients who were already established on anti-retroviral therapy were excluded, 17/95 (25.0%) were seropositive for untreated HIV, and 68/95 (71.6%) patients were H. pylori positive by histology. Hypochlorhydria (fasting gastric pH>4.0) was present in 55.8% (53/95) of patients. H. pylori infection was significantly associated with hypochlorhydria (OR 2.91, [1.02-7.75], p=0.046). While single infection with HIV was not significantly independently associated with hypochlorhydria. H. pylori and HIV co-infection was more strongly associated with hypochlorhydria (OR 6.25, [1.33-29.43], p=0.020) than either infection alone, suggesting an additive effect of co-infection. HIV infection was associated with higher serum gastrin levels (91.3pM vs. 53.1pM, p=0.040), while H. pylori infection was not (63.1pM vs. 55.1pM, p=0.610). Irrespective of H. pylori and HIV status, most patients (>90%) exhibited pangastritis. Only three patients had histological evidence of gastric atrophy, of which only one was HIV-infected.

Conclusion

H. pylori infection was associated with fasting hypochlorhydria, while HIV was not independently associated. HIV and H. pylori co-infection, however, was more strongly associated with hypochlorhydria than H. pylori infection alone. The mechanism of this apparent additive effect between HIV and H. pylori remains unclear, but appears to be related to chronic pangastritis rather than gastric atrophy, and associated with hypergastrinaemia in HIV-infected individuals.     

A pharmacological investigation of Hippophae salicifolia (HS) and Hippophae rhamnoides turkestanica (HRT) against multiple stress (C-H-R): an experimental study using rat model

Hippophae salicifolia (HS) and Hippophae rhamnoides turkestanica (HRT) are abundantly found species of Hippophae in Himalayan region of India. As these plants thrive under extreme climatic conditions, it is suspected that these plants must have a unique adaptogenic property against high-altitude stress. To keeping these views in our mind, the present study was planned to evaluate the mechanism of action of aqueous extract of HS and aqueous extract of HRT against multiple stress [cold-hypoxia-restraint (C-H-R)] for their adaptogenic activity. The present study reported the adaptogenic activity of HS in facilitating tolerance to multiple stress, CHR in rats. Pre-treatment with aqueous extract of HS significantly attenuated reactive oxygen species (ROS) production, protein oxidation, and lipid peroxidation and also showed role in maintaining antioxidant status as similar to control rats. Since protein oxidation was decreased by pre-treatment of HS, protein homeostasis was also sustained by regulation of heat shock proteins (HSP70 and HSP60). Interestingly, heme oxygenase-1 (HO-1), Vascular Endothelial Growth Factor (VEGF), and nitric oxide (NO) level was also increased in HS pre-treated rats depicted its adaptogenic activity against multiple stress, CHR. Conclusively, aqueous extract of HS could use an adaptogen for high altitude-associated multiple stress (CHR).     

Treatment-seeking practices for malaria in pregnancy among rural women in Mukono district, Uganda

Understanding treatment-seeking practices for malaria in pregnancy is necessary in designing effective programmes to address the high malaria morbidity in pregnancy. This study assessed women's perceptions on malaria in pregnancy, recognition of early signs of pregnancy and of malaria, and the cultural context in which treatment seeking takes place in Mukono District. Focus group discussions (FGD) and key informant interviews were conducted among pregnant women, non-pregnant women, adolescents and men. The results showed that malaria, locally known as omusujja, was perceived as the most common cause of ill health among pregnant women. Although malaria commonly presents with fever, some pregnant women feel hot in the womb with or without signs of fever and this illness, locally known as nabuguma, may lead to progressive weakness and occasionally to miscarriage and few respondents associated it with malaria. Primigravidae, adolescents and men were not considered at risk of omusujja or nabuguma. Similarly anaemia and low birth weight were not associated with malaria; in fact paleness was described as a normal sign of pregnancy. There are cultural and social pressures on married women to get pregnant and this forces them to conceal symptoms like feeling feverishness, backache, nausea, general weakness, loss of appetite and vomiting until they are sure these are due to pregnancy. Most women, however, could not differentiate symptoms of malaria from those of early pregnancy. There is a belief that omusujja is a normal sign of pregnancy and this is coupled with a strong cultural practice of using herbs and clays as a first resort to treat pregnancy ailments including malaria. The cultural beliefs and practices regarding delivery of twin and first births, coupled with the high cost of care, prevent women from delivering and using other services at health units.     

The need for systematic reviews of reasons

There are many ethical decisions in the practice of health research and care, and in the creation of policy and guidelines. We argue that those charged with making such decisions need a new genre of review. The new genre is an application of the systematic review, which was developed over decades to inform medical decision-makers about what the totality of studies that investigate links between smoking and cancer, for example, implies about whether smoking causes cancer. We argue that there is a need for similarly inclusive and rigorous reviews of reason-based bioethics, which uses reasoning to address ethical questions. After presenting a brief history of the systematic review, we reject the only existing model for writing a systematic review of reason-based bioethics, which holds that such a review should address an ethical question. We argue that such a systematic review may mislead decision-makers when a literature is incomplete, or when there are mutually incompatible but individually reasonable answers to the ethical question. Furthermore, such a review can be written without identifying all the reasons given when the ethical questions are discussed, their alleged implications for the ethical question, and the attitudes taken to the reasons. The reviews we propose address instead the empirical question of which reasons have been given when addressing a specified ethical question, and present such detailed information on the reasons. We argue that this information is likely to improve decision-making, both directly and indirectly, and also the academic literature. We explain the limitations of our alternative model for systematic reviews.     

Low frequency fatigue in human quadriceps is fatigue dependent and not task dependent.

It is well accepted that a low intensity/long duration isometric contraction induces more low frequency fatigue (LFF) compared to a high-intensity/short-duration contraction. However, previous reports examined the intensity/duration of the contraction but did not control the level of fatigue when concluding fatigue is task dependent. The purpose of this study was to determine whether a long duration/low intensity fatiguing contraction would induce greater LFF than a short duration/high-intensity contraction when the quadriceps muscle was fatigued to similar levels. Eighteen healthy male subjects performed quadriceps contractions sustained at 35% and 65% of maximal voluntary contraction (MVC) on separate days, until the tasks induced a similar amount of fatigue (force generating capacity=45% MVC). Double pulse torque to single pulse torque ratio (D/S ratio) was obtained before, immediately and 5min after fatigue along with the electromyographic (EMG) signal from vastus medialis (VM) and rectus femoris (RF). The D/S ratio significantly (p<0.05) increased by 8.7+/-8.5% (mean+/-SD) and 10.2+/-9.2% after 35% and 65% tasks, respectively, and remained elevated 5min into recovery; however, there was no significant difference in ratio between the two sessions immediately or 5min post-fatigue (p>0.05) even though the endurance time for the 35% fatigue task (124+/-39.68s) was significantly longer (p=0.05) than that of the 65% task (63+/-17.73s). EMG amplitude and median power frequency (MPF) analysis also did not reveal any significant differences between these two sessions after fatigue. These findings indicate that LFF fatigue is fatigue dependent as well as task intensity/duration dependent. These findings assist us in understanding task dependency and muscle fatigue.