Caries and fluorosis prevalence in communities with different concentrations of fluoride in the water

The need to defluoridate and fluoridate the water supplies in areas with drinking water naturally containing above-optimal (>/=2.5 mg/l) and suboptimal (相似文献   

Transgenic animals in toxicology

Recent advances have been made in the characterization of a number of transgenic animal models. These animal models have provided a powerful toxicological tool for studying in vivo chemical effects and have increased our understanding of the role of specific genetic alterations as predisposing factors for chemical carcinogenesis. The goal of this symposium was to introduce the development of transgenic animals and the utilization of transgenics in toxicology research focusing on understanding tissue-specific mutation, chemical effects, and cancer. The production of transgenic animals, including gene insertions and gene knockouts, and the utilization of transgenic technology for studying multistage carcinogenesis and tumor suppressor genes are described. Data on the application and implications of transgenics as a genetic endpoint are also discussed. The use of transgenic animals in toxicology should improve our understanding of the role of specific genetic alterations in the carcinogenic process and lead to improved estimations of human health risks.     

Morphological investigation of sub-micron FePO4 and LiFePO4 particles for rechargeable lithium batteries

Microstructural variations of amorphous FePO₄ and LiFePO₄ (the latter obtained by chemical lithiation of the former) as a result of the annealing temperature have been studied by Thermogravimetric Analysis (TGA)/Differential Thermal Analysis (DTA), chemical analysis, Brunauer-Emmet-Taylor (BET) and Scanning Electron Microscopy (SEM) techniques. Round-shaped amorphous FePO₄ particles 40-80 nm in size are obtained after heating (at 400 °C) amorphous FePO₄·2H₂O in air (previously prepared by a precipitation route). On further heating at 650 °C, in air, crystalline trigonal FePO₄ of crystallite size <200 nm is formed. Round-shaped amorphous LiFePO₄ particles 40-80 nm in size crystallize by heating at 550 °C in Ar+5%H₂ for 3 h. After thermal treatment, LiFePO₄ particles are interconnected by necks, which resembled a sintering process. The particle size of LiFePO₄ increases with an increase of temperature up to 750 °C, but an abnormal growth is evident at annealing temperatures above 650 °C. DTA analysis showed two exothermic peaks at 547 and 768 °C for FePO₄ due to phase transitions, whereas for LiFePO₄ two exothermic effects at 496 and 567 °C are shown.     

A phase I study of high-dose tamoxifen for the treatment of refractory malignant gliomas of childhood

Recent studies have indicated that the proliferation of malignant gliomas is in part dependent on excessive activation of protein kinase C (PKC)-mediated pathways. Conversely, inhibiting PKC may provide a novel approach for blocking glioma growth. The antiestrogen tamoxifen, a moderately potent PKC inhibitor, has been shown in vitro to block the proliferation of malignant glioma cell lines at concentrations several-fold higher than those typically attained during the treatment of breast cancer; such serum concentrations may be achieved with doses > 40 mg/m2 b.i.d. The safety and efficacy of these high doses for producing disease control in patients with malignant gliomas has recently been noted anecdotally, although a rigorous study of this agent has been lacking. To address this issue, we examined the safety and efficacy of high-dose tamoxifen in a series of children with malignant gliomas that had progressed after conventional therapy. An initial group was treated with 60 mg/m2 p.o. b.i.d. and a second group with 100 mg/m2 b.i.d. Steady-state serum tamoxifen and metabolite levels were measured in most patients. Toxicity with the regimen was minimal; two patients treated at the higher dose required reduction to the lower dose because of asymptomatic prolongation of the QT interval on an electrocardiogram. Although none of the patients exhibited clear-cut tumor regression, 4 of 14 patients had stabilization of previously progressive disease for at least 3 months; the longest survivor lived for 17 months after beginning tamoxifen. The moderate efficacy of this agent in otherwise end-stage disease coupled with its low toxicity and the relative ease of oral administration provides a rationale for proceeding with larger studies of this agent in patients with malignant gliomas, possibly as a means for potentiating the effects of conventional chemotherapeutic agents, which to date have shown limited efficacy in the treatment of these tumors.     

The use of immunomodulators in the surgical treatment of complicated gastric disease

While examination of 83 patients it was established that in the presence of complicated gastric and duodenal ulcer disease the secondary immune deficiency is developing, which deepens after the surgical intervention conduction. Tiotriazolin, promoting the immune system state and the blood biochemistry indexes normalization, the immune system state and the blood biochemistry indexes stimulation, hemopoiesis stimulation, the treatment results improvement, was applied for immunomodulation.     

Differential roles of T cell receptor alpha and beta chains in ligand binding among H-2Kd-restricted cytolytic T lymphocyte clones specific for a photoreactive Plasmodium berghei circumsporozoite peptide derivative

To study the interaction of T cell receptor with its ligand, a complex of a major histocompatibility complex molecule and a peptide, we derived H-2Kd-restricted cytolytic T lymphocyte clones from mice immunized with a Plasmodium berghei circumsporozoite peptide (PbCS) 252-260 (SYIPSAEKI) derivative containing photoreactive Nepsilon-[4-azidobenzoyl] lysine in place of Pro-255. This residue and Lys-259 were essential parts of the epitope recognized by these clones. Most of the clones expressed BV1S1A1 encoded beta chains along with specific complementary determining region (CDR) 3beta regions but diverse alpha chain sequences. Surprisingly, all T cell receptors were preferentially photoaffinity labeled on the alpha chain. For a representative T cell receptor, the photoaffinity labeled site was located in the Valpha C-strand. Computer modeling suggested the presence of a hydrophobic pocket, which is formed by parts of the Valpha/Jalpha C-, F-, and G-strands and adjacent CDR3alpha residues and structured to be able to avidly bind the photoreactive ligand side chain. We previously found that a T cell receptor specific for a PbCS peptide derivative containing this photoreactive side chain in position 259 similarly used a hydrophobic pocket located between the junctional CDR3 loops. We propose that this nonpolar domain in these locations allow T cell receptors to avidly and specifically bind epitopes containing non-peptidic side chains.