Production and characterisation of polyclonal antibodies to a derivative of 3-amino-2-oxazolidinone, a metabolite of the nitrofuran furazolidone

Polyclonal antibodies were produced to detect 3-amino-2-oxazolidinone (AOZ), a stable metabolite of the nitrofuran antibiotic furazolidone, following derivatisation with o-nitrobenzaldehyde. A carboxyphenyl derivative of AOZ was prepared, purified and conjugated to immunogenic carrier protein. Six antisera were produced from the immunisation of seven rabbits using various immunogen doses and time-scales. IC₅₀ values, as determined by competitive enzyme-linked immunosorbent assay (ELISA) suggested that reducing immunogen dose from 0.3 to 0.05 mg, while lengthening rest periods between booster immunisations from 2 to 8 weeks, increased the sensitivity of the antibodies to 3-{[(2-nitrophenyl)methylene]amino}-2-oxazolidinone (NPAOZ) from 3.8 to 0.3 μg l⁻¹. An IC₅₀ of 0.065 μg l⁻¹ (AOZ in the form of NPAOZ) was achieved with antiserum R670 by altering ELISA conditions. This antibody was highly specific for NPAOZ and did not cross-react with various nitrofuran metabolites, their nitrophenyl derivatives or a range of veterinary drugs. Antibody R670 is suitable for incorporation into an immunoassay for AOZ with sufficient sensitivity to satisfy current criteria for monitoring of veterinary drug residues. This is the first publication of an antibody for detection of a nitrofuran metabolite.     

Establishing norms for age-related changes in proton T1 of human brain tissue in vivo

The goal of this study was to determine the expected normal range of variation in spin-lattice relaxation time (T₁) of brain tissue in vivo, as a function of age. A previously validated precise and accurate inversion recovery method was used to map T₁ transversely, at the level of the basal ganglia, in a study population of 115 healthy subjects (ages 4 to 72; 57 male and 58 female). Least-squares regression analysis shows that T₁ varied as a function of age in pulvinar nucleus (R² = 56%), anterior thalamus (R² = 51%), caudate (R² = 50%), frontal white matter (R² = 47%), optic radiation (R² = 39%), putamen (R² = 36%), genu (R² = 22%), occipital white matter (R² = 20%) (all p < 0.0001), and cortical gray matter (R² = 53%) (p < 0.001). There were no significant differences in T₁ between men and women. T₁ declines throughout adolescence and early adulthood, to achieve a minimum value in the fourth to sixth decade of life, then T₁ begins to increase. Quantitative magnetic resonance imaging provides evidence that brain tissue continues to change throughout the lifespan among healthy subjects with no neurologic deficits. Age-related changes follow a strikingly different schedule in different brain tissues; white matter tracts tend to reach a minimum T₁ value, and to increase again, sooner than do gray matter tracts. Such normative data may prove useful for the early detection of brain pathology in patients.     

Structure determination of a tetradecapeptide mimicking the RXVRG consensus sequence recognized by a Xenopus laevis skin endoprotease: An approach based on simulated annealing and 1H NMR

Summary The tetradecapeptide of sequence H-Asp-Val-Asp-Glu-Arg ⁵-Asp-Val-Arg-Gly⁹-Phe-Ala-Ser-Phe-Leu-NH₂ is recognized by a putative maturation endoprotease of the Xenopus laevis skin, which cleaves between Arg⁸ and Gly⁹. A conformational search has been performed on this peptide by simulated annealing calculations. Two different models in agreement with the NMR data were found. The conformational difference between the two types of model is located in the consensus sequence, i.e., from Arg⁵ to Gly⁹.     

Use of capillary electrophoresis to monitor wheat maturation

Summary The maturation of wheat varieties with different harvest times has been examined by high-performance capillary electrophoresis. The unique proteins of the albumin, gliadin and glutenin fractions of Hungarian winter wheat cultivars Bánkúti 1201 (early harvest time), Martonvásári 23 (medium harvest time), and Martonvásári 15 (semi-late harvest time) were analysed. An acidic phosphate buffer containing a polymeric additive and organic modifiers was used in capillary zone electrophoresis mode. Formation of albumin followed the same time scale, and the patterns were quite similar, for all three cultivars. For gliadins and glutenins the time scale and patterns were different and some correlation was observed between harvest time and gliadin formation. Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001     

Oxygen-Deficient Molybdenum Oxide Nanosensitizers for Ultrasound-Enhanced Cancer Metalloimmunotherapy

Oxygen-deficient molybdenum oxide (MoO_X) nanomaterials are prepared as novel nanosensitizers and TME-stimulants for ultrasound (US)-enhanced cancer metalloimmunotherapy. After PEGylation, MoO_X-PEG exhibits efficient capability for US-triggered reactive oxygen species (ROS) generation and glutathione (GSH) depletion. Under US irradiation, MoO_X-PEG generates a massive amount of ROS to induce cancer cell damage and immunogenic cell death (ICD), which can effectively suppress tumor growth. More importantly, MoO_X-PEG itself further stimulates the maturation of dendritic cells (DCs) and triggeres the activation of the cGAS-STING pathway to enhance the immunological effect. Due to the robust ICD induced by SDT and efficient DC maturation stimulated by MoO_X-PEG, the combination treatment of MoO_X-triggered SDT and aCTLA-4 further amplifies antitumor therapy, inhibits cancer metastases, and elicits robust immune responses to effectively defeat abscopal tumors.     

The dynamics of pest control pollution model with age structure and time delay

In this paper, by using pollution model and impulsive delay differential equation, we investigate the dynamics of a pest control model with age structure for pest by introducing a constant periodic pesticide input and releasing natural enemies at different fixed moment. We assume only the pests are affected by pesticide. We show that there exists a global attractive pest-extinction periodic solution when the periodic natural enemies release amount μ₁ and pesticide input amount μ₂ are larger than some critical value. Further, the condition for the permanence of the system is also given. By numerical analyses, we also show that constant maturation time delay, pulse pesticide input and pulse releasing of the natural enemies can bring obvious effects on the dynamics of system. We believe that the results will provide reliable tactic basis for the practical pest management.     

The dynamics of a mutual interference age structured predator-prey model with time delay and impulsive perturbations on predators

In this paper, we introduce a mutual interference age structured predator-prey (natural enemy-pest) model with constant maturation time delay for the prey, and then propose a pest management strategy by constant periodic releasing for the predator. We show that there exists a global attractive pest-eradication periodic solution when the periodic releasing amount μ₁ and μ₂ are lager than some critical value. Further, to obtain a more effective pest control strategy, we give the conditions (involving the estimate of μ₁ and μ₂) in which the model is uniformly permanent and the pest population is under the economic threshold level. We believe that the results will provide reliable tactic basis for the practical pest management.     

Mathematical assessment of the role of non-linear birth and maturation delay in the population dynamics of the malaria vector

A delay ordinary deterministic differential equation model for the population dynamics of the malaria vector is rigorously analysed subject to two forms of the vector birth rate function: the Verhulst-Pearl logistic growth function and the Maynard-Smith-Slatkin function. It is shown that, for any birth rate function satisfying some assumptions, the trivial equilibrium of the model is globally-asymptotically stable if the associated vectorial reproduction number is less than unity. Further, the model has a non-trivial equilibrium which is locally-asymptotically stable under a certain condition. The non-trivial equilibrium bifurcates into a limit cycle via a Hopf bifurcation. It is shown, by numerical simulations, that the amplitude of oscillating solutions increases with increasing maturation delay. Numerical simulations suggest that the Maynard-Smith-Slatkin function is more suitable for modelling the vector population dynamics than the Verhulst-Pearl logistic growth model, since the former is associated with increased sustained oscillations, which (in our view) is a desirable ecological feature, since it guarantees the persistence of the vector in the ecosystem.     

Separation of the unique proteins of wheat protein fractions by capillary electrophoresis

Summary The wheat maturation process was monitored by high-performance capillary electrophoresis. The different protein components of the albumin, globulin, gliadin and glutenin fractions from the Osborne extraction procedure were analysed. The wheat sample was a Hungarian winter wheat, cultivar Martonvásári 23. The protein fractions were analysed by capillary zone electrophoresis using a low pH phosphate buffer containing a polymeric additive and organic modifiers. The albumins and gliadins as well as glutenins showed a characteristic pattern of development during the maturation process. For these fractions the development occurred at different stages of maturation. The formation of protein fractions of wheat at different stages of maturation—and thus the entire maturation process—could be well characterised by high-performance capillary electrophoresis. Presented at Balaton Symposium on High Performance Separation Methods, Siófok, Hungary, September, 1–3, 1999