Calcium Signaling in Plant Endosymbiotic Organelles： Mechanism and Role in Physiology

Recent studies have demonstrated that chloroplasts and mitochondria evoke specific Ca2＋ signals in response to biotic and abiotic stresses in a stress-dependent manner. The identification of Ca2＋ transporters and Ca2＋signaling mol- ecules in chloroplasts and mitochondria implies that they play roles in controlling not only intra-organellar functions, but also extra-organellar processes such as plant immunity and stress responses. It appears that organellar Ca2＋ signaling might be more important to plant cell functions than previously thought. This review briefly summarizes what is known about the molecular basis of Ca2＋ signaling in plant mitochondria and chloroplasts.     

TUBERCULOSIS—Recent Trends in Infection,Disease and Deaths in California

Although fewer patients with tuberculosis are reported in a far advanced stage of the disease than ever before, the proportion of persons dying of tuberculosis whose disease had not previously been diagnosed appears to be increasing. The average length of sanatorium treatment, and the intramural case fatality rates have not shown much decrease. Tuberculosis mortality rates fall during economic depressions and rise with business booms. Epidemics of influenza do not always increase tuberculosis death rates. Common claims to the contrary are not sustained by recent California data.     

What Are They Up To? The Role of Sensory Evidence and Prior Knowledge in Action Understanding

Explaining or predicting the behaviour of our conspecifics requires the ability to infer the intentions that motivate it. Such inferences are assumed to rely on two types of information: (1) the sensory information conveyed by movement kinematics and (2) the observer's prior expectations--acquired from past experience or derived from prior knowledge. However, the respective contribution of these two sources of information is still controversial. This controversy stems in part from the fact that "intention" is an umbrella term that may embrace various sub-types each being assigned different scopes and targets. We hypothesized that variations in the scope and target of intentions may account for variations in the contribution of visual kinematics and prior knowledge to the intention inference process. To test this hypothesis, we conducted four behavioural experiments in which participants were instructed to identify different types of intention: basic intentions (i.e. simple goal of a motor act), superordinate intentions (i.e. general goal of a sequence of motor acts), or social intentions (i.e. intentions accomplished in a context of reciprocal interaction). For each of the above-mentioned intentions, we varied (1) the amount of visual information available from the action scene and (2) participant's prior expectations concerning the intention that was more likely to be accomplished. First, we showed that intentional judgments depend on a consistent interaction between visual information and participant's prior expectations. Moreover, we demonstrated that this interaction varied according to the type of intention to be inferred, with participant's priors rather than perceptual evidence exerting a greater effect on the inference of social and superordinate intentions. The results are discussed by appealing to the specific properties of each type of intention considered and further interpreted in the light of a hierarchical model of action representation.     

POSTMATURITY SYNDROME—The Obstetrician's Role in Management

The obstetric problem of going past the date of expected confinement has no medical significance, provided the fetus in its demands does not outgrow placental capability. The problem of relative placental insufficiency, however, is a serious one with a total fetal wastage in the neighborhood of 15 per cent.Antepartum indications of such placental insufficiency have not yet been well documented. However, a decrease in the fundal measurements and particularly where associated with an otherwise unexplained loss of maternal weight has proved an ominous sign.In a study of application of reported criteria for determining when a patient is “at term” by vaginal cytologic methods, the results were approximately 75 per cent accurate. Cytologic studies when coupled with other physical findings may be of assistance in determining in which cases labor should be induced and in which the fetuses should be accorded the special attention that is demanded by the chronic state of low grade anoxia.     

The Role of Zoos in Modern Society—A Comparison of Zoos' Reported Priorities and What Visitors Believe They Should Be

Modern zoos are required to fulfill a growing number of responsibilities including scientific research, wildlife conservation, public recreation, and education. With so many roles and responsibilities and limited funds, zoos have to prioritize their activities in relation to their own specified goals, objectives, and mission statements. Given their desire to nurture community relations and educational opportunities, it is important to determine the extent to which zoos are prioritizing their activities, according to visitors' expectations. This paper presents empirical research of a two staged mixed-methods investigation into zoo priorities from both zoos' and visitors' perspectives. The first stage involved an online questionnaire to which more than 190 zoos across 52 countries reported their priorities and activities. We then undertook in-depth case studies in nine institutions, enabling direct observation of each site within its context, including face-to-face visitor interviews. Our research contrasts the priority given to zoo activities from each perspective and indicates that educating visitors, including school children, is the highest priority activity from the zoos' perspective and that of their visitors. The findings also show that visitors place high value on learning about actions they can take to help conservation efforts. Some inconsistencies between zoos' and visitors' priorities were also evident, such as the different emphasis placed on viewing endemic species, and zoos being a place for people to relax and socialize. The implications of these findings are discussed.     

Lights,Rhythms, Infection: The Role of Light and the Circadian Clock in Determining the Outcome of Plant–Pathogen Interactions

The importance of light with respect to the outcome of plant–pathogen interactions is becoming increasingly evident: light affects both the host response and the virulence of some pathogens. The response of plants to environmental signals and stresses is modulated by the circadian clock, and it is apparent that this may include immune responses. Photo and temporal regulation of immune responses may allow plants to anticipate and react more effectively to particular pathogen infections. These aspects of regulation are sometimes overlooked when designing experiments to understand plant–pathogen interactions, complicating the interpretation of the outcomes and the direct comparisons of studies. We review recent key findings in these areas and discuss the implications for experimental design and analyses.     

The Role of Viral Infection in Pest Control: A Mathematical Study

In this paper, we propose a mathematical model of viral infection in pest control. As the viral infection induces host lysis which releases more virus into the environment, on the average ‘κ’ viruses per host, κ∈(1,∞), so the ‘virus replication parameter’ is chosen as the main parameter on which the dynamics of the infection depends. There exists a threshold value κ ₀ beyond which the infection persists in the system. Still for increasing the value of κ, the endemic equilibrium bifurcates towards a periodic solution, which essentially indicates that the viral pesticide has a density-dependent ‘numerical response’ component to its action. Investigation also includes the dependence of the process on predation of natural enemy into the system. A concluding discussion with numerical simulation of the model is also presented.     

The Role of Wnt/β-Catenin Signaling in Enterocyte Turnover during Methotrexate-Induced Intestinal Mucositis in a Rat

Background/Aims

Intestinal mucositis is a common side-effect in patients who receive aggressive chemotherapy. The Wnt signaling pathway is critical for establishing and maintaining the proliferative compartment of the intestine. In the present study, we tested whether Wnt/β-catenin signaling is involved in methotrexate (MTX)-induced intestinal damage in a rat model.

Methods

Non-pretreated and pretreated with MTX Caco-2 cells were evaluated for cell proliferation and apoptosis using FACS analysis. Adult rats were divided into three experimental groups: Control rats; MTX-2 animals were treated with a single dose of MTX given IP and were sacrificed on day 2, and MTX-4 rats were treated with MTX similar to group B and were sacrificed on day 4. Intestinal mucosal damage, mucosal structural changes, enterocyte proliferation, and enterocyte apoptosis were measured at sacrifice. Real Time PCR and Western blot was used to determine the level of Wnt/β-catenin related genes and protein expression.

Results

In the vitro experiment, treatment with MTX resulted in marked decrease in early cell proliferation rates following by a 17-fold increase in late cell proliferation rates compared to early proliferation. Treatment with MTX resulted in a significant increase in early and late apoptosis compared to Caco-2 untreated cells. In the vivo experiment, MTX-2 and MTX-4 rats demonstrated intestinal mucosal hypoplasia. MTX-2 rats demonstrated a significant decrease in FRZ-2, Wnt 3A Wnt 5A, β-catenin, c-myc mRNA expression and a significant decrease in β-catenin and Akt protein levels compared to control animals. Four days following MTX administration, rats demonstrated a trend toward a restoration of Wnt/β-catenin signaling especially in ileum.

Conclusions

Wnt/β-catenin signaling is involved in enterocyte turnover during MTX-induced intestinal mucositis in a rat.     

The Role of Peroxisome Proliferator-Activated Receptor γ in Immune Responses to Enteroaggregative Escherichia coli Infection

Background

Enteroaggregative Escherichia coli (EAEC) is recognized as an emerging cause of persistent diarrhea and enteric disease worldwide. Mucosal immunity towards EAEC infections is incompletely understood due in part to the lack of appropriate animal models. This study presents a new mouse model and investigates the role of peroxisome proliferator-activated receptor gamma (PPARγ) in the modulation of host responses to EAEC in nourished and malnourished mice.

Methods/Principal Findings

Wild-type and T cell-specific PPARγ null C57BL/6 mice were fed protein-deficient diets at weaning and challenged with 5×10⁹cfu EAEC strain JM221 to measure colonic gene expression and immune responses to EAEC. Antigen-specific responses to E. coli antigens were measured in nourished and malnourished mice following infection and demonstrated the immunosuppressive effects of malnutrition at the cellular level. At the molecular level, both pharmacological blockade and deletion of PPARγ in T cells resulted in upregulation of TGF-β, IL-6, IL-17 and anti-microbial peptides, enhanced Th17 responses, fewer colonic lesions, faster clearance of EAEC, and improved recovery. The beneficial effects of PPARγ blockade on weight loss and EAEC clearance were abrogated by neutralizing IL-17 in vivo.

Conclusions

Our studies provide in vivo evidence supporting the beneficial role of mucosal innate and effector T cell responses on EAEC burden and suggest pharmacological blockade of PPARγ as a novel therapeutic intervention for EAEC infection.     

Cytokines in Brain Ischemia—The Role of TNFα

1. The role of cytokines and other inflammatory mediators in the progression of ischemic brain injury is a new and exciting era of research. Evidence in support for a role for TNF in this respect is emerging as evidence on de novo upregulation of TNF following ischemia is now well established.2. TNF administered directly to the brain parenchyma elicits local microvascular injury in the form of pericapillary edema and leukocyte adhesion to cerebral capillaries.3. TNF administered into the cerebroventricular space prior to ischemia augment the extent of tissue damage and neurological deficits.4. Specific and potent inhibitors of TNF synthesis or TNF receptors must be developed and tried to prove firmly a role for TNF in ischemic brain injury.