The evolution of primate malaria parasites based on the gene encoding cytochrome b from the linear mitochondrial genome

We report a phylogenetic analysis of primate malaria parasites based on the gene encoding the cytochrome b protein from the mitochondrial genome. We have studied 17 species of Plasmodium, including 14 parasitic in primates. In our analysis, four species were used for rooting the Plasmodium phylogenetic tree: two from closely related genera (Hepatocystis sp. and Haemoproteus columbae) and two other Apicomplexa (Toxoplasma gondii and Theileria parva). We found that primate malaria parasites form a monophyletic group, with the only exception being the Plasmodium falciparum-Plasmodium reichenowi lineage. Phylogenetic analyses that include two species of non-Plasmodium Haemosporina suggest that the genus Plasmodium is polyphyletic. We conclude that the biologic traits, such as periodicity and the capacity to relapse, have limited value for assessing the phylogenetic relationships among Plasmodium species. For instance, we found no evidence that would link virulence with the age of the host-parasite association. Our studies also reveal that the primate malaria parasites originated in Africa, which contradicts the presently held opinion of Southeast Asia as their center of origin. We propose that the radiation of Asian monkey parasites is a recent event where several life history traits, like differences in periodicity, appeared de novo.     

Expression of NO-synthase in cells of foreign-body and BCG-induced granulomata in mice: influence of L-NAME on the evolution of the lesion

Plasmodium inui (Halberstaedter and von Prowazek, 1907), a malarial parasite of Old World monkeys that occurs in isolated pockets throughout the Celebes, Indonesia, Malaysia, and the Philippines, has traditionally been considered to be related more closely to Plasmodium malariae of humans (and its primate counterpart Plasmodium brasilianum), than to other primate Plasmodium species. This inference was made in part because of the similarities in the periodicities or duration of the asexual cycle in the blood, the extended sporogonic cycle, and the longer period of time for development of the pre-erythrocytic stages in the liver. Both P. inui and P. malariae have quartan (72 hr) periodicities associated with their asexual cycle, whereas other primate malarias, such as Plasmodium fragile and Plasmodium cynomolgi, are associated with tertian periodicities (48 hr), and Plasmodiumn knowlesi, with a quotidian (24 hr) periodicity. Phylogenetic analyses of portions of orthologous small subunit ribosomal genes reveal that P. inui is actually more closely related to the Plasmodium species of the "vivax-type" lineage than to P. malariae. Ribosomal sequence analysis of many different, geographically isolated, antigenically distinct P. inui isolates reveals that the isolates are nearly identical in sequence and thus members of the same species.     

Cloning and characterization of the human and Caenorhabditis elegans homologs of the Saccharomyces cerevisiae MSH5 gene

Genetic variation among malaria parasites has important consequences with regard to drug resistance, pathogenicity, immunity, transmission, and speciation. In this regard, malaria parasites have been shown to display a high degree of inter- and intra-species genetic divergence. The nuclear genomes of Plasmodium falciparum, Plasmodium yoelii, and Plasmodium gallinaceum are vastly divergent yet share a similar codon usage and total A/T content of approximately 82%. This is in contrast to other primate-specific species including P. vivax which have an A/T content of approximately 67%. To assess the effects of this evolutionary divergence on the conservation of gene content, organization, and codon usage in the mitochondrial DNA (mtDNA) of malaria parasites, we have cloned and sequenced the mitochondrial genome of Plasmodium vivax, and compared it with the mtDNAs of P. falciparum, P. yoelii, and P. gallinaceum. The P. vivax mitochondrial genome was found to be 5990 base pairs in length, and displayed a gene organization identical to that of P. falciparum, P. yoelii, and P. gallinaceum. Furthermore, there was a remarkable 90% conservation of sequence identity between the mitochondrial genomes of all four species. As an example of intra-species conservation, comparison of mtDNAs from two independently cloned P. falciparum isolates, Malay Camp and C10, revealed only a single nucleotide substitution. A/T content of the P. vivax mitochondrial genome was found to be identical to other species of Plasmodium, hence, we have postulated that the mitochondrial genomes of malaria parasites were refractory to the evolutionary shifts in nucleotide content seen among the nuclear genomes of malaria parasites. Among different Plasmodium species, the second position of mitochondrial codons were found to be the least prone to substitutions and displayed a significant bias in pyrimidines. These aspects of mitochondrial codon usage were distinct from the nuclear genome and may reflect functional aspects of decoding by the mitochondrial translational system.     

Innovative System for Off-the-Ground Rotation of Long Objects Using Mobile Cranes

Managing heavy-pressure vessel lifts on construction sites requires planning, arranging adequate crane support, and preparing collision-free rotation (from a horizontal position to a vertical position) of the vessel. Generally, selecting mobile cranes and developing engineered lift studies for vessels are done using two cranes and analyzing the lift for each crane individually on the basis of the selected cranes’ lift-capacity specifications provided by crane manufactures. This practice is relatively costly and time-consuming. Optimizing the mobile cranes’ use and location is also difficult. To assist in the field operation of mobile cranes and to provide engineers with a planning tool, this paper presents a methodology to carry out such a lift utilizing only one crane. Using the developed methodology and mechanism, heavy vessels can be rotated off the ground (in the air) with one crane. The proposed mechanism is supported with a mathematical model that has been developed into a computer system and has been integrated with a previously developed crane selection and ground pressure calculation system and crane database. The developed system provides users with a lift study analysis for a given configuration as well as simulation results with interactive graphics to assist in the selection of an optimum configuration. This research is important as projects involving heavy lifts need to reduce the cost and time associated with construction operations.     

Computational Methods for Coordinating Multiple Construction Cranes

The incremental coordination method a computational method for preplanning and coordinating the use of multiple tower cranes in relatively narrow construction sites is presented. The incremental coordination method considers the kinematics and the geometrical constraints of cranes to plan the motion of two or more cranes, which are being operated in collaboration. By following such planned motions, erection tasks are completed safely, even when the cranes are operated in close proximity of each other. This method allows the use of computers to plan and coordinate the crane activities from start to end of an erection process. This paper also explains the computational methods required by the incremental coordinate method including path-finding and collision detecting methods. An example case shows two construction cranes, each of three degrees-of-freedom, operating together on a building project where the working areas of the cranes intersect, hence possibility colliding with each other. A numerical test was conducted to verify the efficiency and effectiveness of applying the incremental coordination method in planning and synchronizing all motions of the two cranes to avoid any collision between the cranes themselves and collision with obstacles on the construction site.     

Hemagglutination with crane herpesvirus

A crane herpesvirus (CrHV) grown in chicken embryo fibroblast (CEF) cells was tested for hemagglutination (HA) with erythrocytes from a variety of species at 4 degrees C, room temperature and 37 degrees C. HA was observed at all temperatures with erythrocytes from mouse, ddY and BALB/c strains, but not with those from cattle, sheep and chicken. Mice, ddY strain, showed an individual variation in agglutinability of their erythrocytes and erythrocytes from BALB/c gave a higher HA titer. The HA activity was inhibited by the sera obtained from naturally infected cranes, experimentally infected duck and immunized rabbit with CrHV. HI antibody titers of these sera showed a closely positive correlation with their neutralizing antibody titers.     

Comparison of circumsporozoite proteins from avian and mammalian malarias: biological and phylogenetic implications

The circumsporozoite (CS) protein of malaria parasites (Plasmodium) covers the surface of sporozoites that invade hepatocytes in mammalian hosts and macrophages in avian hosts. CS genes have been characterized from many Plasmodium that infect mammals; two domains of the corresponding proteins, identified initially by their conservation (region I and region II), have been implicated in binding to hepatocytes. The CS gene from the avian parasite Plasmodium gallinaceum was characterized to compare these functional domains to those of mammalian Plasmodium and for the study of Plasmodium evolution. The P. gallinaceum protein has the characteristics of CS proteins, including a secretory signal sequence, central repeat region, regions of charged amino acids, and an anchor sequence. Comparison with CS signal sequences reveals four distinct groupings, with P. gallinaceum most closely related to the human malaria Plasmodium falciparum. The 5-amino acid sequence designated region I, which is identical in all mammalian CS and implicated in hepatocyte invasion, is different in the avian protein. The P. gallinaceum repeat region consists of 9-amino acid repeats with the consensus sequence QP(A/V)GGNGG(A/V). The conserved motif designated region II-plus, which is associated with targeting the invasion of liver cells, is also conserved in the avian protein. Phylogenetic analysis of the aligned Plasmodium CS sequences yields a tree with a topology similar to the one obtained using sequence data from the small subunit rRNA gene. The phylogeny using the CS gene supports the proposal that the human malaria P. falciparum is significantly more related to avian parasites than to other parasites infecting mammals, although the biology of sporozoite invasion is different between the avian and mammalian species.     

Crane-Related Fatalities in the Construction Industry

One of the major causes of fatalities during construction is the use of cranes or derricks during lifting operations. Using the Occupational Safety and Health Administration’s (OSHA) case files from fatality investigations during the years 1997–2003, the writers examined the data to determine the proximal causes and contributing physical factors. The research results showed the use of mobile cranes with lattice and telescopic booms, truck or crawler mounted, represented over 84% of the fatalities in the use of cranes/derricks. To reduce the rate of crane fatalities the writers believe that crane operators and riggers should be qualified and requalification should occur every 3?years. Crane safety training must be provided to specialty trade crafts before they are allowed to work around cranes during lifting operations. In addition, a “diligent” competent person [as defined in 29CFR 1926.32(f)] should be in charge of all aspects of lifting operations. Finally, OSHA should improve its system of collecting information during fatality investigations, placing emphasis on intervention strategies to improve usefulness of the investigations to researchers and policymakers inside and outside the Agency.     

Simulation-Based Identification of Possible Locations for Mobile Cranes on Construction Sites

Identifying spatial-conflict free locations of mobile cranes that could minimize delays associated with crane relocation can result in productivity and safety improvements on construction sites. Existing approaches for identifying possible crane locations are based on two-dimensional (2D) work envelopes created by reasoning about the lift capacities of a crane during operations. Since spatial conflicts related to crane operations typically occur in three dimensions and during any period of operation, representing possible crane locations based on such 2D work envelopes can result in identifying some locations as good when in fact they might result in conflicts and missing possible locations that might be feasible. This paper presents an approach that determines possible locations of mobile cranes based on discrete-event simulation of crane operations incorporating dynamic behaviors of cranes. This approach starts with identifying a search space for possible crane locations by reasoning about a reachability radius of a crane determined by crane characteristics and the weight of the load to be carried. Later, it reduces the search space through boom-line intersection tests. For the remaining locations, it checks for potential spatial conflicts between building components and cranes moving in three dimensions and across time. Validation studies show that the developed approach can accurately identify possible locations for mobile cranes that minimize the relocation of mobile cranes and avoid potential spatial conflicts.     

Measurement and Risk Scales of Crane-Related Safety Factors on Construction Sites

This paper addresses quantitative measurement and risk scales of safety hazards on construction sites due to the work of tower cranes. Hazard measurement and risk scales are essential components of an integrated model aimed at quantitatively determining the safety level of individual construction sites, on a comparative basis. The paper focuses on two factors identified in earlier studies as considerably affecting safety on sites with tower cranes, “overlapping cranes” and “operator proficiency.” These two factors are inherently different from each other in their characteristics and therefore also in the methods used to measure both the factors and the risk resulting from them. A probability-based method was prescribed for the measurement of overlapping cranes, while the analytical hierarchy process method and knowledge elicitation from experts were applied to develop metrics for operator proficiency. In both cases, an intimate understanding of the crane work environment is necessary. The uniform format and specific methodologies presented here can be used in the development of measurement techniques and risk scales for other safety factors concerning crane operation on construction sites.     

Cranes for Building Construction Projects

Cranes have come to symbolize building construction itself. They perform indispensable services in moving materials and components vertically and horizontally. Used since antiquity, their history is interrelated with the development of new power sources that replaced man and mule, first steam and later internal combustion, diesel, and electric engines. Mobile cranes can be rapidly deployed to lift heavy loads. New models with telescoping booms and all-terrain travel capability, compact urban machines, and even hybrids with tower cranes are beginning to replace the familiar lattice boom truck cranes. Mobile cranes have dominated the North American market, but a cultural change appears to be taking place toward tower cranes for building projects. Tower cranes, common in Europe for decades, are globally gaining in popularity with surging real estate developments. Ideal for dense urban environments and coming with a small footprint, they are available in a growing diversity of sizes and configurations. Sophisticated electronic controls and operator assistance devices are enhancing their safe and productive operation. While cranes occupy a central role on midrise and high-rise building projects, they operate in conjunction with other types of supporting equipment that are an essential part of the overall equipment array on today’s industrialized construction sites.     

吊车紧急响应系统的设计与应用

阐述了吊车重物意外坠落的危险性,设计了吊车紧急响应系统,提高了设备在紧急情况下的反应速度,解决了人工操作具有延迟性的问题,避免了重物坠落重大事故的发生.     

Antimalarial activity of novel arylene bis(methylketone) compounds

Because of the spread of drug-resistant Plasmodium species, there is an urgent need for novel effective antimalarial agents. A series of arylene bis(methylketone) compounds were screened in vitro against a number of Plasmodium falciparum clones and in vivo against Plasmodium berghei. 2-amino-4-(3,5-diacetylphenyl)amino-1,6-dimethylpyrimidinium chloride (Cytokine Network Inc. [CNI]-H0294) was the most effective of the compounds in vitro, with an IC50 of 1.5-4.0 microM against parasite clones with a wide range of sensitivities to chloroquine and pyrimethamine. Other compounds in the series had in vitro IC50 values of 20-25 microM. In a 4-day test for suppression of P. berghei parasitemia in vivo, 50 mg/kg/day CNI-H0294 significantly decreased parasitemia by >90%. The compound was found to have low toxicity in mice, with an LD50 of 590 +/- 66 mg/kg intraperitoneally, and rapid plasma kinetics. These results show that CNI-H0294 has considerable antimalarial activity and merits further study.     

Plasmodium (Giovannolaia) pedioecetii from gallinaceous birds of Colorado

Forty-nine Colorado birds of 6 galliform species were positive for Plasmodium (Giovannolaia) pedioecetii which we feel to be the same parasite described by Wetmore (1939) from a shaptailed grouse from North Dakota. Except for its presence in Darwin's tinamou (Nothura darwinii) from Colorado, it has been reported only from gallinaceous birds. Most stages were predominantly subpolar to polar. There were a daily 8 am to noon peak of merozoite production, but no synchronicity. Merozoite number ranged from 8 to 22, with a mean of 10.9. Gametocytes were long and slender, some curving around one end of the host nucleus.     

Polypyrimidine tract-binding protein positively regulates inclusion of an alternative 3''-terminal exon

A leading candidate for a vaccine targeted at the erythrocytic stages of plasmodial parasite development is the merozoite surface protein-1 (MSP-1). We have previously shown that the carboxyl-terminal region of MSP-1 derived from Plasmodium yoelii yoelii 17XL, expressed as a fusion protein with glutathione S-transferase (GST-PYC2), can immunize mice against an otherwise lethal homologous challenge infection. This protection has been shown to be predominantly mediated by antibodies. We report here on the efficacy of immunization with MSP-1 carboxyl regions when the challenge is a heterologous rodent parasite species. The course of parasitemia was not altered in mice immunized with GST-PYC2 and challenged with 10(4) heterologous Plasmodium chabaudi adami parasites, as both control and immunized mice developed infections that peaked at day 7 and then rapidly declined. Similarly, mice immunized with GST-PYC2 and challenged with 10(5) Plasmodium berghei ANKA parasites displayed virulence similar to that seen in infection control mice. The homologous region of the P. chabaudi adami MSP-1 gene was similarly expressed as a fusion protein with GST. Mice immunized with GST-PCC2 and challenged with 10(4) parasites showed significant protection against homologous P. chabaudi adami infection but no protection whatsoever against heterologous P. yoelii yoelii 17XL infection. These in vivo results correlate with the observation that sera generated by immunization with the carboxyl region of MSP-1 recognizes this protein from homologous, but not heterologous, radiolabeled parasite protein preparations.     

变频调速控制系统在桥式起重机上的优势分析

通过对传统桥式起重机电动机转子串电阻调速控制系统存在安全隐患多、效率低、耗能高等缺点,以及对变频调速控制系统应用在桥式起重机上的优势进行分析比较,充分体现变频调速控制系统应用在桥式起重机上是非常理想的选择。     

轧钢成品库无人天车与货车调度协同优化

为了研究轧钢库区货车入库高效调度和无人天车作业合理分配协同优化问题,针对轧钢成品库区产品多品种小批量、出入库频繁等特点,建立了以订单服务时间最小为目标的整数规划模型,然后通过仿真试验对天车分配规则进行学习,并在不同订单规模下对经验规则、遗传算法和自适应遗传算法3种调度方法进行了对比试验.试验结果和现场验证均表明在各个订...     

狭窄厂房空间150t钢包回转台安装方案介绍

针对狭窄厂房空间150 t钢包回转台的安装,研究设计了专用的两跨双台行车联合抬吊方案。设计和制造了双台行车联合抬吊的平衡梁吊具,并针对小曲率穿索半径,设计制造了专用的尼龙吊带进行穿索吊装。通过结合过渡支架平台的设计安装,运用两跨双台行车联合抬吊的新方案,成功实施了狭窄厂房空间150 t钢包回转台的安装,并保证了安装精度,安装过程安全可靠。     

Plasmodium forresteri n. sp., from raptors in Florida and southern Georgia: its distinction from Plasmodium elongatum morphologically within and among host species and by vector susceptibility

Plasmodium forresteri n. sp. naturally infects eastern screech-owls (Otus asio), great horned owls (Bubo virginianus), barred owls (Strix varia), bald eagles (Haliaeetus leucocephalus), red-shouldered hawks (Buteo lineatus), broad-winged hawks (Buteo platypterus), and red-tailed hawks (Buteo jamaicensis) in Florida and southern Georgia. Schizonts occur in mature or nearly mature erythrocytes, produce 2-6 merozoites arranged most commonly in fan or cruciform configuration, with mean dimensions among host species varying from 3.7 to 4.8 x 2.5 to 3.4 microns. Gametocytes are elongate, with mean dimensions among host species varying from 11.5 to 13.1 x 2.0 to 2.4 microns. One or both gametocyte margins are irregular and often crenulate. Gametocytes seldom fill the space between the erythrocyte nucleus and margin. Species characteristics were maintained in isodiagnostic Japanese quail (Coturnix japonica) and Pekin ducks (Anas platyrhynchos). In mosquito infection studies, only Culex restuans could support sporogony of P. forresteri, in contrast to Plasmodium elongatum of raptor origin that completed sporogony in both Cx. restuans and Culex nigripalpus.