117 research outputs found
Duality in interacting particle systems and boson representation
In the context of Markov processes, we show a new scheme to derive dual
processes and a duality function based on a boson representation. This scheme
is applicable to a case in which a generator is expressed by boson creation and
annihilation operators. For some stochastic processes, duality relations have
been known, which connect continuous time Markov processes with discrete state
space and those with continuous state space. We clarify that using a generating
function approach and the Doi-Peliti method, a birth-death process (or discrete
random walk model) is naturally connected to a differential equation with
continuous variables, which would be interpreted as a dual Markov process. The
key point in the derivation is to use bosonic coherent states as a bra state,
instead of a conventional projection state. As examples, we apply the scheme to
a simple birth-coagulation process and a Brownian momentum process. The
generator of the Brownian momentum process is written by elements of the
SU(1,1) algebra, and using a boson realization of SU(1,1) we show that the same
scheme is available.Comment: 13 page
Stem cell factor and its soluble receptor (c-kit) in serum of asthmatic patients- correlation with disease severity
<p>Abstract</p> <p>Background</p> <p>SCF (stem cell factor) is a pleiotropic cytokine exerting its role at different stages of bone marrow development and affecting eosinophil activation, mast cells and basophil chemotaxis and survival. The aim of the study was to assess concentration of SCF and its soluble receptor c-kit (sc-kit) in peripheral blood of patients with asthma referring it to asthma severity and phenotype.</p> <p>Methods</p> <p>The study involved 107 patients with bronchial asthma, well characterized with respect to severity and 21 healthy controls. Concentration of SCF and sc-kit in the patients serum were measured by ELISA method.</p> <p>Results</p> <p>Mean serum SCF level in the group of asthmatics (n = 88) was significantly higher as compared to healthy controls (1010 pg/ml ± 37 vs 799 ± 33; p < 0,001). The level of SCF was higher in patients with severe asthma as compared to patients with non-severe asthma (1054 +/- 41 pg/ml vs 819 +/- 50; p < 0,01) and correlated with dose of inhaled glucocorticosteroids taken by the patients to achieve asthma control (R = 0,28; p < 0,01). The mean sc-kit serum level did not differ between asthmatic patients and healthy controls, however the level of sc-kit in non-severe asthmatics was significantly higher as compared to patients with severe asthma and healthy controls. In asthmatic patients (n = 63) the level of sc-kit correlated positively with FEV1% predicted value (R = 0,45; p < 0,001) and MEF25% predicted value (R = 0,33; p < 0,01). The level of sc-kit inversely correlated with the dose of inhaled glucocorticosteroids taken by the patients (R = -0,26; p < 0,01).</p> <p>Conclusion</p> <p>Serum levels of SCF and its soluble receptor c-kit seem to be reflect asthma severity suggesting a role for these molecules in asthmatic inflammation.</p
Analytical in vitro approach for studying cyto- and genotoxic effects of particulate airborne material
In the field of inhalation toxicology, progress in the development of in vitro methods and efficient exposure strategies now offers the implementation of cellular-based systems. These can be used to analyze the hazardous potency of airborne substances like gases, particles, and complex mixtures (combustion products). In addition, the regulatory authorities require the integration of such approaches to reduce or replace animal experiments. Although the animal experiment currently still has to provide the last proof of the toxicological potency and classification of a certain compound, in vitro testing is gaining more and more importance in toxicological considerations. This paper gives a brief characterization of the CULTEX® Radial Flow System exposure device, which allows the exposure of cultivated cells as well as bacteria under reproducible and stable conditions for studying cellular and genotoxic effects after the exposure at the air–liquid or air–agar interface, respectively. A commercial bronchial epithelial cell line (16HBE14o-) as well as Salmonella typhimurium tester strains were exposed to smoke of different research and commercial available cigarettes. A dose-dependent reduction of cell viability was found in the case of 16HBE14o- cells; S. typhimurium responded with a dose-dependent induction of revertants. The promising results recommend the integration of cellular studies in the field of inhalation toxicology and their regulatory acceptance by advancing appropriate validation studies
Plasma fibrin D-dimer levels correlate with tumour volume, progression rate and survival in patients with metastatic breast cancer
Plasma levels of D-dimer are elevated in cancer patients. Activation of the extrinsic coagulation system and the fibrinolytic cascade within a tumour is thought to be related with growth, invasion and metastasis. We have investigated the relationship between these markers of fibrin metabolism, standard clinicopathological variables and serum levels of angiogenic cytokines in three cohorts: group A (n=30) consisted of 30 healthy female volunteers, group B (n=23) of consecutive patients with operable breast cancer and group C (n=84) of patients with untreated or progressive metastatic breast cancer. Plasma D-dimers, fibrinogen, IL-6, vascular endothelial growth factor and calculated vascular endothelial growth factor load in platelets are clearly increased in patients with breast cancer. D-dimers were increased in nearly 89% of patients with progressive metastatic disease. The level of D-dimers was positively correlated with tumour load (P<0.0001), number of metastatic sites (P=0.002), progression kinetics (P<0.0001) and the cytokines related to angiogenesis: serum vascular endothelial growth factor (P=0.0016, Spearman correlation=0.285), calculated vascular endothelial growth factor load in platelets (P<0.0001, Spearman correlation=0.37) and serum interleukin-6 (P<0.0001, Spearman correlation=0.59). Similarly increased D-dimer levels were positively correlated with increased fibrinogen levels (P<0.0001, Spearman correlation=0.38). The association between markers of fibrin degradation in patients with progressive breast cancer suggests that the D-dimer level is a clinically important marker for progression and points towards a relation between haemostasis and tumour progression. A role of interleukin-6, by influencing both angiogenesis and haemostasis, is suggested by these observations
Effects of GnRH vaccination in wild and captive African Elephant bulls (Loxodonta africana) on reproductive organs and semen quality
OBJECTIVES:
Although the African elephant (Loxodonta africana) is classified as endangered by the International
Union for Conservation of Nature (IUCN), in some isolated habitats in southern Africa,
contraception is of major interest due to local overpopulation. GnRH vaccination has been
promoted as a non-invasive contraceptive measure for population management of overabundant
wildlife. We tested the efficacy of this treatment for fertility control in elephant bulls.
METHODS:
In total, 17 male African elephants that were treated with a GnRH vaccine were examined in
two groups. In the prospective study group 1 (n = 11 bulls, ages: 8±36 years), semen quality,
the testes, seminal vesicles, ampullae and prostate, which were all measured by means of
transrectal ultrasound, and faecal androgen metabolite concentrations were monitored over
a three-year period. Each bull in the prospective study received 5 ml of Improvac® (1000 μg
GnRH conjugate) intramuscularly after the first examination, followed by a booster six
weeks later and thereafter every 5±7 months. In a retrospective study group (group 2, n = 6,
ages: 19±33 years), one examination was performed on bulls which had been treated with
GnRH vaccine for 5±11 years.
RESULTS:
In all bulls of group 1, testicular and accessory sex gland sizes decreased significantly after
the third vaccination. In six males examined prior to vaccination and again after more than
five vaccinations, the testis size was reduced by 57.5%. Mean testicular height and length
decreased from 13.3 ± 2.6 cm x 15.2 ± 2.8 cm at the beginning to 7.6 ± 2.1 cm x 10.2 ± 1.8
cm at the end of the study. Post pubertal bulls (>9 years, n = 6) examined prior to vaccination
produced ejaculates with viable spermatozoa (volume: 8±175 ml, sperm concentration:
410-4000x106/ml, total motility: 0±90%), while after 5±8 injections, only 50% of these bulls
produced ejaculates with a small number of immotile spermatozoa. The ejaculates of group
2 bulls (vaccinated >8 times) were devoid of spermatozoa. Faecal androgen metabolite concentrations
measured in captive males decreased significantly after the fourth vaccination.
None of the males entered musth during the treatment period.
CONCLUSIONS:
Our results showed a marked decrease in semen quality, testicle and secondary sex gland
sizes following repeated GnRH vaccinations. After 2±4 years of continuous treatment every
5±7 months, the effects were similar to surgical castration.ISIScopu
Characterization and social correlates of fecal testosterone and cortisol excretion in wild male Saguinus mystax
Reproductive success in male primates can be influenced by testosterone (T) and cortisol (C). We examined them in wild Saguinus mystax via fecal hormone analysis. Firstly, we wanted to characterize male hormonal status over the course of the year. Further we tested the influence of the reproductive status of the breeding female, social instability, and intergroup encounter rates on T levels, comparing the results with predictions of the challenge hypothesis (Wingfield et al., 1990). We also tested for interindividual differences in hormonal levels, possibly related to social or breeding status. We collected data during a 12-mo study on 2 groups of moustached tamarins at the Estación Biológica Quebrada Blanco in northeastern Peru. We found fairly similar T and C levels over the course of the year for all males. Yet an elevation of T shortly after the birth of infants, during the phase of ovarian inactivity of the group’s breeding female, was evident. Hormonal levels were not significantly elevated during a phase of social instability, did not correlate with intergroup encounter rates, and did not differ between breeding and nonbreeding males. Our results confirm the challenge hypothesis (Wingfield et al., 1990). The data suggest that reproductive competition inmoustached tamarins is not based on endocrinological, but instead on behavioral mechanisms, possibly combined with sperm competition.Deutsche Forschungsgemeinschaft (HE 1870/10-1,2
Nucleotide-Oligomerization-Domain-2 Affects Commensal Gut Microbiota Composition and Intracerebral Immunopathology in Acute Toxoplasma gondii Induced Murine Ileitis
Background Within one week following peroral high dose infection with
Toxoplasma (T.) gondii, susceptible mice develop non-selflimiting acute
ileitis due to an underlying Th1-type immunopathology. The role of the innate
immune receptor nucleotide-oligomerization-domain-2 (NOD2) in mediating
potential extra-intestinal inflammatory sequelae including the brain, however,
has not been investigated so far. Methodology/Principal Findings Following
peroral infection with 100 cysts of T. gondii strain ME49, NOD2-/- mice
displayed more severe ileitis and higher small intestinal parasitic loads as
compared to wildtype (WT) mice. However, systemic (i.e. splenic) levels of
pro-inflammatory cytokines such as TNF-α and IFN-γ were lower in NOD2-/- mice
versus WT controls at day 7 p.i. Given that the immunopathological outcome
might be influenced by the intestinal microbiota composition, which is shaped
by NOD2, we performed a quantitative survey of main intestinal bacterial
groups by 16S rRNA analysis. Interestingly, Bifidobacteria were virtually
absent in NOD2-/- but not WT mice, whereas differences in remaining bacterial
species were rather subtle. Interestingly, more distinct intestinal
inflammation was accompanied by higher bacterial translocation rates to extra-
intestinal tissue sites such as liver, spleen, and kidneys in T. gondii
infected NOD2-/- mice. Strikingly, intracerebral inflammatory foci could be
observed as early as seven days following T. gondii infection irrespective of
the genotype of animals, whereas NOD2-/- mice exhibited higher intracerebral
parasitic loads, higher F4/80 positive macrophage and microglia numbers as
well as higher IFN-γ mRNA expression levels as compared to WT control animals.
Conclusion/Significance NOD2 signaling is involved in protection of mice from
T. gondii induced acute ileitis. The parasite-induced Th1-type immunopathology
at intestinal as well as extra-intestinal sites including the brain is
modulated in a NOD2-dependent manner
Enhanced susceptibility of triple transgenic Alzheimer’s disease (3xTg-AD) mice to acute infection
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