On the threshold conditions for electron beam damage of asbestos amosite fibers in the transmission electron microscope (TEM)

Asbestos amosite fibers were investigated to evaluate the damage caused by a transmission electron microscope (TEM) electron beam. Since elemental x-ray intensity ratios obtained by energy dispersive x-ray spectroscopy (EDS) are commonly used for asbestos identification, the impact of beam damage on these ratios was evaluated. It was determined that the magnesium/silicon ratio best represented the damage caused to the fiber. Various tests showed that most fibers have a current density threshold above which the chemical composition of the fiber is modified. The value of this threshold current density varied depending on the fiber, regardless of fiber diameter, and in some cases could not be determined. The existence of a threshold electron dose was also demonstrated. This value was dependent on the current density used and can be increased by providing a recovery period between exposures to the electron beam. This study also established that the electron beam current is directly related to the damage rate above a current density of 165 A/cm². The large number of different results obtained suggest, that in order to ensure that the amosite fibers are not damaged, analysis should be conducted below a current density of 100 A/cm².     

Population cytogenetic and molecular evidence for existence of a new species in Anopheles fluviatilis complex (Diptera: Culicidae)

Anopheles fluviatilis James, an important malaria vector in the Oriental region has been established as a complex of at least three cryptic species which vary in their biological characteristics and malaria transmission potential. The sibling species S, T and U of Fluviatilis Complex can be identified by examination of species-specific fixed inversions in the polytene chromosomes and can also be differentiated by an allele-specific PCR assay based on differences in the D3 region of 28S ribosomal DNA (rDNA) of these species. Here we report a new An. fluviatilis population from villages under Laksar Community Health Centre, District Haridwar (Uttarakhand state), India which differs from the three sibling species of Fluviatilis Complex by two fixed paracentric inversions, s¹ and S in polytene chromosome arms 2 and 3 respectively. Longitudinal study carried out in study villages showed that the new cytotype was sympatric with species T and U in all the collections and no inversion heterozygotes were observed between them. Thus presence of two fixed paracentric inversions in polytene chromosomes with total absence of inversion heterozygotes demonstrates reproductive isolation which unequivocally establishes this cytological variant as a new species, provisionally designated as species V in the Fluviatilis Complex. Analysis of DNA sequences of D3 domain of 28S rDNA and ITS 2 region has also shown that species V is distinctly different from species S, T and U. With the discovery of new species in the Fluviatilis Complex, in-depth studies are required to know its distribution pattern and biological characteristics and to ascertain its role in malaria transmission.     

Relieved residual damage in the hematopoietic system of mice rescued by radiation-induced adaptive response (Yonezawa Effect)

Existence of adaptive response (AR) was previously demonstrated in C57BL/6J mice. Irradiations were performed by delivering a priming low dose of X-rays (0.50 Gy) in combination with a challenge high dose of accelerated carbon or neon ion particles. AR was characterized by significantly decreased mortality in the 30-day survival test. This mouse AR model (‘Yonezawa Effect’) was originally established by using X-rays as both the priming and challenge irradiations. The underlying mechanism was due to radio-resistance occurring in blood-forming tissues. In this study, we verified the existence of AR and further investigated residual damage in the hematopoietic system in surviving animals. Results showed that the priming low dose of X-rays could relieve the detrimental effects on the hematopoietic system. We observed both an improvement in the blood platelet count and the ratio of polychromatic erythrocytes (PCEs) to the sum of PCEs and normochromatic erythrocytes (NCEs) and a marked reduction of the incidences of micronucleated PCEs and micronucleated NCEs. These findings suggest that the priming low dose of low linear energy transfer (LET) X-rays induced a protective effect on the hematopoietic system, which may play an important role in both rescue from acute lethal damage (mouse killing) and prevention of late detrimental consequences (residual anhematopoiesis and delayed genotoxic effects) caused by exposure to a high challenge dose from low-LET (X-ray) or high-LET (carbon and neon ion) irradiations. These findings provide new knowledge of the characterization of the Yonezawa Effect by providing new insight into the mechanistic study of AR in vivo.     

浙江地区耐多药结核分枝杆菌基因突变特征分析

目的 分析浙江地区耐多药结核分枝杆菌(M.tuberculosis complex,MTBC)异烟肼(isoniazid,INH)和利福平(rifampicin,RIF)耐药相关基因突变特征.方法 对患者痰标本阳性培养物进行菌种鉴定,提取耐多药菌株DNA,应用PCR法对inhA、katG和rpoB RRDR区进行扩增,...     

Shake-flask test for determination of biodegradation rates of (14)C-labeled chemicals at low concentrations in surface water systems

A simple shake-flask surface water biodegradability die away test with (14)C-labeled chemicals added to microgram per liter concentrations (usually 1-100 microg/L) is described and evaluated. The aim was to provide information on biodegradation behavior and kinetic rates at environmental (low) concentrations in surface water systems. The basic principle of measurement was to determine evolved CO(2) indirectly from measurements of total organic activity in subsamples after stripping off their content of CO(2). Used with surface water alone the test simulates a pelagic environment and amended with sediments (0.1-1 dry weight/L) the test is intended to simulate a water environment with suspended solids (e.g., resuspended sediments). A protocol of the test used with the (14)C technique or with specific chemical analysis was recently developed by the International Organization for Standardization. Practical experience with the method is presented for a set of reference substances. These substances could be ranked in five groups of decreasing biodegradability: aniline>p-nitrophenol, 2, 4-dichlorophenoxyacetic acid>4-chloroaniline>maleic hydrazide, pentachlorophenol>atrazine. It was found that degradation rates and lag periods varied considerably among sampling sites and sometimes also among samples from the same site. No significant correlation could be established between degradation rates and microbial biomass estimates. Even small portions of added sediments greatly enhanced biodegradation of the absorbable compound pentachlorophenol, probably by providing sites for microbial attachment. Repeated tests indicated consistent degradation behavior for the readily degradable substances, whereas degradation sometimes stopped or failed with the more recalcitrant substances. A preadaptation step involving regular reinoculation with freshly collected surface water could, however, overcome the problems of false-negative results.     

低营养要素在Kashin-Beck Disease(KBD)发病中的作用

目的:综述低硒、低碘、低维生素、低蛋白、低微量元素等营养要素在大骨节病中的作用。方法:广泛查阅关于KBD病因的相关文章,并进行综合分析。结果:低硒、低碘、低维生素、低蛋白、低微量元素统称为低营养要素,但都不能完全的解释KBD的发病原因和机制。结论:KBD的发生、发展是多因素、多病因作用的结果,单纯从某一个方面或某一要素都很难完全解释其真正的发病机制。     

MEFV基因突变与儿童过敏性紫癜遗传易感性的Meta分析

目的 探讨MEFV基因突变与过敏性紫癜(HSP)的相关性.方法 计算机检索PubMed、Web of Science、Medline、Cochrane Library、中国期刊全文数据库(CNKI)、万方数据库,检索从建库至2015年12月31日公开发表的关于MEFV基因突变与HSP相关性的文献,使用Rev Man 5.0软件进行Meta分析.结果 最终纳入6篇英文文献,累计总病例数433例,其中MEFV基因突变136例,Meta分析结果显示合并的MEFV基因突变率为0.3(95％ CI:0.23,0.37);3个亚组(关节炎组、消化道症状组、肾脏损害组)每组中MEFV基因突变与非突变比较均P＞0.05,提示MEFV基因突变与临床症状无显著性差异.结论 MEFV基因突变可能是儿童HSP遗传易感因素,但在临床表现方面MEFV基因突变与非突变无明显的区别.     

Sensitivity of perceptuomotor measures for very low birthweight (VLBW ≤ 1500 g) pre-schoolers

Summary This longitudinal study investigated whether very low birthweight (VLBW ≶ 1500 g) pre-schoolers with no major handicap differed in cognitive and perceptuomotor development from a control group of normal birthweight children, matched for gender, ethnic origin, birth order, social class and maternal age. There were statistically significant differences between the groups at 24, 30 and 36 months. At all test ages, the VLBW group showed less optimal fine motor skills, and at 36 months, obtained lower IQ scores. The implications of the developmental differences and the sensitivity of the measures are discussed.     

一种新型立体定向放射治疗系统剂量(X刀)

研制了一种新型立体定向放射治疗系统剂量(X刀)测量水箱。其采用内外两层(大小)水箱结构,两者通过潜水泵和输水管连接,实现内水箱的水位控制。新型水箱具有自动调节、结构简单和使用方便的特点,值得临床推广。     

SPICE-NIRS Microbeam: a focused vertical system for proton irradiation of a single cell for radiobiological research

The Single Particle Irradiation system to Cell (SPICE) facility at the National Institute of Radiological Sciences (NIRS) is a focused vertical microbeam system designed to irradiate the nuclei of adhesive mammalian cells with a defined number of 3.4 MeV protons. The approximately 2-μm diameter proton beam is focused with a magnetic quadrupole triplet lens and traverses the cells contained in dishes from bottom to top. All procedures for irradiation, such as cell image capturing, cell recognition and position calculation, are automated. The most distinctive characteristic of the system is its stability and high throughput; i.e. 3000 cells in a 5 mm × 5 mm area in a single dish can be routinely irradiated by the 2-μm beam within 15 min (the maximum irradiation speed is 400 cells/min). The number of protons can be set as low as one, at a precision measured by CR-39 detectors to be 99.0%. A variety of targeting modes such as fractional population targeting mode, multi-position targeting mode for nucleus irradiation and cytoplasm targeting mode are available. As an example of multi-position targeting irradiation of mammalian cells, five fluorescent spots in a cell nucleus were demonstrated using the γ-H2AX immune-staining technique. The SPICE performance modes described in this paper are in routine use. SPICE is a joint-use research facility of NIRS and its beam times are distributed for collaborative research.     

Evaluation of the immune responses against reduced doses of Brucella abortus S19 (calfhood) vaccine in water buffaloes (Bubalus bubalis), India

BackgroundBrucella abortus S19 is the most widely used vaccine for the prevention of bovine brucellosis which remains the reference vaccine to which many other vaccine/s are compared. Considering the larger vaccination coverage by reduced dose of vaccine, the study aimed to compare reduced graded doses (1/10th, 1/20th and 1/100th) with standard dose of S19 vaccine (40 × 10⁹CFU /dose) to determine the effective immunizing dose in water buffaloes.MethodsA total of 25 female buffalo calves (Bubalus bubalis) in the age group of 4–5 months were equally grouped into five animals each in four test and one control groups and given with specified vaccine dose. The blood samples were collected on post vaccination days 14, 28, 45, 60, 90 and 120 for assessing innate (TNF-α and IL-12), humoral (IgG antibodies against Brucella LPS) and cell mediated immune responses (IFN-γ, CD4 + and CD8 + counts).ResultsThe full dose, 1/10th and 1/20th reduced doses of S19 vaccine was capable of eliciting pathogen-specific antibody response, vaccine induced secretion of IL-12, TNF-α and IFN-γ with CD4 + and CD8 + effector T cell responses. Persistence of antibody and magnitude of immune responses were found dose dependent.ConclusionComparable immune responses were noticed with 1/10th reduced dose similar to standard dose. With this observation, decline of antibody titre will reduce the number of false positives and reduced dose of vaccine will facilitate larger vaccination coverage in the country.     

Morphological evidence suggests homoploid hybridization as a possible mode of speciation in the Triatominae (Hemiptera,Heteroptera, Reduviidae)

All known significant insect vectors of Trypanosoma cruzi are members of the Reduviidae, subfamily Triatominae. Infections with this parasite are the cause of Chagas disease, the single most costly parasitic disease in the Western Hemisphere. The Triatominae are almost completely restricted to the Americas, with >130 species distributed in several foci of species richness and endemism; nevertheless, the processes involved in the diversification of this group remain poorly understood. The Triatoma brasiliensis species complex was recently proposed based on geography, morphology, ecology, and molecular data, and is believed to comprise two species and two subspecies. Here, we report results from a broad series of studies, in which first-generation offspring of experimental crosses were studied in terms of wing morphometry and phylogenetic position. Morphometrics, morphological, ecological and geographic analyses were consistent with the hypothesis of T. brasiliensis macromelasoma as a product of hybridization between two others (T. brasiliensis brasiliensis and T. juazeirensis). Although evidence is supportive of the hypothesis of speciation via hybridization as a mode of triatomine diversification, the case is not as-yet conclusive, and confirmation via molecular markers is necessary.     

Field-based evidence for linkage of mutations associated with chloroquine (pfcrt/pfmdr1) and sulfadoxine-pyrimethamine (pfdhfr/pfdhps) resistance and for the fitness cost of multiple mutations in P. falciparum.

Mutations in the Plasmodium falciparum pfcrt gene on chromosome 7 and possibly mutations in pfmdr1 on chromosome 5 have a role in conferring resistance against chloroquine (CQ), as do mutations of pfdhfr on chromosome 4 and pfdhps on chromosome 8 in terms of resistance against sulfadoxine/pyrimethamine (SP). The additive role of multiple mutations in the development of resistance to each drug suggests a non-random occurrence. In this study, parasite isolates were obtained from 50 patients with uncomplicated P. falciparum malaria from rural Eastern Sudan, an endemic setting with minimal overlap of infection. The parasite isolates were genotyped for detection of 12 alleles in CQ and SP resistance genes. Our main findings were: (1) the frequency of mutant alleles, pfcrt K76T, pfmdr1 N86Y, pfdhfr N51I, pfdhfr S108N, pfdhps K540E and pfdhps A581G were; 0.90, 0.86, 0.84, 0.84, 0.80 and 0.20, respectively. (2) No mutations were detected for the pfdhfr loci A16V, C59R and I164L, and for pfdhps loci S436A, A437G and A613S. (3) There was a statistically significant association between the mutations in: (i) the CQ resistance (CQR) genes, pfcrt T76 and pfmdr1 Y86 (P< or =0.001), (ii) the SP resistance (SPR) genes, pfdhfr I51, pfdhfr N108 and pfdhps E540 (P< or =0.001-0.04) and (iii) the CQ "i" and SP "ii" resistance genes (P=0.001) 4. The fitness cost of multiple mutations was revealed by a significantly reduced parasite density of isolates bearing the mutant alleles (P=0.048). However, the significantly higher gametocyte carriage rate among isolates with resistance mutations (P=0.001) is possibly an evolutionary mechanism for survival of mutant parasites.     

Report of varicella outbreak in a low vaccination coverage group of otherwise healthy children in Italy: the role of breakthrough and the need of a second dose of vaccine

We describe an outbreak of varicella at a preschool center in Southern Italy, in the period January–May 2009, among children with a vaccination coverage of 53.9% for one dose.     

一种感觉神经定量测定仪的研制

开发一种以一片89C51单片机、一个精密正弦波发生器和一个高压恒流输出电路为核心，可产生3种不同频率(2000Hz、250Hz和5Hz)的正弦波精密恒定电流输出的感觉神经定量测定仪。其刺激输出强度范围为0．01mA--10．00mA。该仪器能比较客观地判断神经感觉状况，为临床神经病变的诊断提供一种新方法。