Members of the USF family of helix-loop-helix proteins bind DNA as homo- as well as heterodimers

Free-living haematophagous insects risk death through host grooming responses or through increased susceptibility to predation whenever they take a bloodmeal. In this paper we investigate the effects of these risks on the feeding strategy of tsetse. A model is presented that allows for death of tsetse by starvation if they do not succeed in feeding within a fixed time (set at 6 days in the first instance) and for mortality specifically associated with feeding. In addition there is background mortality that applies to all flies at all times. The model is used to compute the individual life-time fertility (number of female puparia per female) as a function of the probability of obtaining a meal (indicated by field data to be very high, usually > 0.85 per day) and the day on which flies start to search for a meal. We suggest that the feeding strategy that would be selected for is that which allows the maximum reproductive output. The model shows that this strategy involves making no attempts to feed for 3-4 days after the previous meal and then attempting to feed with the greatest possible probability until a meal is obtained. The predicted feeding interval, obtained independently of any trapping data, agrees closely with all previous estimates from field studies using a variety of methods. Preliminary results from a laboratory experiment reveal an increased risk of predation of recently fed as compared with hungry tsetse. The lower the actual feeding mortality the more frequently will flies be able to feed should conditions so demand. It is adaptive, however, for tsetse to delay attempting to feed for as long as they can, which is made possible by the near certainty of locating and feeding on a host within 1 day, using their sophisticated sensory systems.     

Approaches to vector control: new and trusted. 2. Molecular targets in the insect midgut

The midgut of blood-feeding insects is an important site for the activity of antibodies and drugs ingested with the blood meal. These agents can be directed at molecular targets in the midgut, and may affect the insect directly by reducing its fitness, or indirectly by blocking transmission of a disease organism to the vector. Both of these result in eventual disease control. Immunization with crude vector or parasite preparations can result in isolation of vaccine candidates which are very effective but often of unknown function. Conversely, by examining carefully the vector's biology and its interactions with the parasite, it is possible to identify various physiological or cellular systems and vector-parasite interactions that can be interfered with. Examples of both approaches are presented in this paper. Anti-vector vaccines offer tremendous potential for disease control, as they can affect the parasite reproductive rate in a number of ways--reducing vector longevity, fecundity or competence. This is most striking if life expectancy of the vector is reduced to a period less than the extrinsic life cycle of the parasite. The rationale often presented for examining molecular systems in vectors is their control potential; it is clearly appropriate to re-examine many of these systems and realistically assess their applicability.     

The reaction of S-nitrosoglutathione with superoxide

The gut peptide glucagon-like peptide 1(7-36) amide (GLP-1) is released into the circulation after food intake. GLP-1 has been shown to have an incretin effect and inhibits gastrointestinal motility in humans. In rats, intracerebral administration of GLP-1 results in reduced food intake. Obese humans have been found to have an attenuated plasma GLP-1 response to a mixed meal. To approximate the physiologic state, GLP-1 or saline was administered intravenously and randomly at the beginning of a test meal served on a universal eating monitor to 6 obese subjects to test our hypothesis that GLP-1 influences termination of food intake (and thus food intake during a meal) and feelings of satiety in humans. As a marker for gastric emptying, 1.5 g acetaminophen was given at the start of the meal. Blood samples for analysis of acetaminophen, insulin, glucose, glucagon, and C-peptide were obtained. Hunger, fullness, and food choice were assessed with visual analogue scales and food-choice questionnaires. GLP-1 infusion resulted in a prolonged period of reduced feelings of hunger, desire to eat, and prospective consumption after the meal. The rate of gastric emptying was slower during infusion of GLP-1. Postprandial blood glucose concentrations were reduced during the GLP-1 infusion, but the amount of energy consumed, eating rate, and plasma concentrations of insulin, glucagon, and C-peptide were unchanged. GLP-1 given exogenously at the start of a meal did not seem to affect meal termination or the amount of food eaten. However, postprandial feelings of hunger decreased, suggesting that exogenous GLP-1 may influence feelings of hunger and satiety in humans.     

Characterisation of rhizobia from African acacias and other tropical woody legumes using Biolog and partial 16S rRNA sequencing

Blood was collected from two Sahelian goats, experimentally infected with either a drug-sensitive cloned population of Trypanosoma congolense (IL 1180) or a multiple drug-resistant T. congolense stock (Samorogouan/89/CRTA/267) and incubated at 37 degrees C for 30 min and 12 h, respectively, in the presence of different drug concentrations (0.5, 1.0, 10.0 and 100.0 microg/ml blood) of diminazene aceturate or isometamidium chloride. After that, the trypanosome/blood/drug suspensions were offered to tsetse flies (2100 teneral Glossina morsitans submorsitans) through an in vitro feeding system, using a silicone membrane. All tsetse flies were dissected and examined for the presence of trypanosomes in labrum, hypopharynx and midgut 20 days after their infective blood-meals. Infectivity of the drug-sensitive cloned population was already completely abolished after incubation with 0.5 microg/ml of both drugs; however, 13.6-42.2% of tsetse having been fed on untreated blood had developed an infection. In contrast, no significant differences were observed in the infection rates between the experimental groups and their control groups when fed on blood infected with the multiple drug-resistant stock after incubation for 30 min with up to 10 microg/ml of diminazene or isometamidium. In consequence, tsetse appear to be a useful tool in the assessment of drug susceptibility of typanosome populations.     

An application of signal detection theory with finite mixture distributions to source discrimination.

A mixture extension of signal detection theory is applied to source discrimination. The basic idea of the approach is that only a portion of the sources (say A or B) of items to be discriminated is encoded or attended to during the study period. As a result, in addition to 2 underlying probability distributions associated with the 2 sources, there is a 3rd distribution that represents items for which sources were not attended to. Thus, over trials, the observed response results from a mixture of an attended (A or B) distribution and a nonattended distribution. The situation differs in an interesting way from detection in that, for detection, there is mixing only on signal trials and not on noise trials, whereas for discrimination, there is mixing on both A and B trials. Predictions of the mixture model are examined for data from several recent studies and in a new experiment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A1 is a constitutive and inducible Bcl-2 homologue in mature human neutrophils

Digestion of blood within the mosquito midgut is mediated primarily by a series of proteases, and several previous studies have described protease activity within homogenates of the midgut of the malaria vector Anopheles stephensi. We have expanded on these previous data by resolving protease isoforms from the midgut as well as the hemolymph of adult An. stephensi mosquitoes via gel electrophoresis and zymography. Using this procedure, we have been able to identify multiple isozymes of trypsin, chymotrypsin, and aminopeptidase. We were able to detect an increase in the intensity of some of these protease bands plus the appearance of new bands 24 hr after mosquitoes had taken a blood meal. Furthermore, we detected 2 endogenous trypsin isozymes within the hemolymph. There was no upregulation of these hemolymph isozymes after a blood meal, thus suggesting that they may not be involved in digestion of the blood meal by the mosquito.     

Effect of age and loading rate on human cervical spine injury threshold

STUDY DESIGN: Statistical analysis of human cadaver cervical spine compression experiments. OBJECTIVES: To quantify the cervical spine compressive injury threshold as a function of the person's age, gender, and external loading rate. SUMMARY OF BACKGROUND DATA: Results of epidemiologic studies have indicated that most survivors of cervical spinal cord injury have spinal column fractures and dislocations that result from a compression or compression-flexion force vector. Cervical spinal column injury thresholds are dependent on many factors. Delineation of the injury thresholds according to age, gender, and loading rate is necessary to improve clinical assessments and prevention strategies. METHODS: Twenty-five human cadaver head-neck compression tests were included in the analysis. Two statistical models were used to quantify the effects of age, gender, and loading rate on the force required to induce failure in the cervical spine. A multiple linear regression model provided a direct equation that quantified the effects of the variables, and a proportional hazards model was used to quantify probability of injury with each factor. RESULTS: The regression model had a correlation coefficient of 0.87. There was an interactive effect between age and loading rate: Increasing age reduced the effect of loading rate and at approximately 82 years, loading rate had no effect. Men were consistently 600 N stronger than women. The 50% probability of failure for a 50-year-old man at a 4.5-m/sec loading rate was approximately 3.9 kN. Differences in probability curves followed the same trends as seen in the regression model. CONCLUSIONS: The effects of age on cervical spine injury threshold are coupled with the rate of loading experienced through the external force vector that causes the trauma. Assessment of injury mechanisms and thresholds should be based on the person's age, gender, and loading rate to determine treatment and prevent injuries.     

Plasminogen is required for efficient dissemination of B. burgdorferi in ticks and for enhancement of spirochetemia in mice

The role of the host plasminogen activation system in transmission of and invasion by Borrelia burgdorferi, the tick-borne spirochetal agent of Lyme disease, was investigated using plasminogen (Plg)-knockout mice. PLG was not detected in spirochetes from unfed ticks, but binding occurred as ticks fed on the host's blood. Plasminogen activators were derived from the host blood meal. PLG was required for efficient dissemination of B. burgdorferi within the tick and for enhancement of spirochetemia in mice but was not critical for transmission and infection. These results provide evidence for a bacterium using a vertebrate protease to disseminate in an invertebrate vector and underscores the interplay among vector, pathogen, and host in promoting the life cycle and disease.     

A comparison of use of a pyrethroid either for house spraying or for bednet treatment against malaria vectors

In an intensely malarious area in north-east Tanzania, microencapsulated lambdacyhalothrin was used in four villages for treatment of bednets (provided free of charge) and in another four villages the same insecticide was used for house spraying. Another four villages received neither intervention until the end of the trial but were monitored as controls. Bioassays showed prolonged persistence of the insecticidal residues. Light traps and ELISA testing showed reduction of the malaria vector populations and the sporozoite rates, leading to a reduction of about 90% in the entomological inoculation rate as a result of each treatment. Collections of blood fed mosquitoes showed no diversion from biting humans to biting animals. Incidence of re-infection was measured by weekly monitoring of cohorts of 60 children per village, after clearing preexisting infection with chlorproguanil-dapsone. The vector control was associated with a reduction in probability of re-infection per child per week by 54-62%, with no significant difference between the two vector control methods. Cross-sectional surveys for fever, parasitaemia, haemoglobin and weight showed association of high parasitaemia with fever and anaemia and beneficial effects of each intervention in reducing anaemia. However, passive surveillance by resident health assistants showed no evidence for reduced prevalence of fever or parasitaemia. Net treatment consumed only about one sixth as much insecticide as house spraying and it was concluded that the former intervention would work out cheaper and nets were actively demanded by the villagers, whereas spraying was only passively assented to.     

变频矢量控制系统入侵检测技术

针对采用以太网控制自动化技术(EtherCAT)工业总线的感应电机交-直-交变频矢量控制系统的入侵检测技术进行了研究. 首先通过对EtherCAT总线协议进行深度解析, 结合目前为止已经发现的EtherCAT工业总线常见协议漏洞, 提取协议数据包的关键特征并构建EtherCAT总线协议入侵检测规则库, 采用三维指针链表树作为针对EtherCAT总线协议规则库的检索数据结构; 其次, 根据感应电机交-直-交变频矢量控制系统的物理模型, 进行模型参数仿真计算, 并根据仿真计算值, 构建矢量控制模型入侵特征的最小二乘支持向量机(least square support vector machine, LSSVM)分类器, 使用混沌粒子群优化(choatics particle swarm optimization, CPSO)算法对分类器的参数进行优化, 二者共同构成了CPSO-LSSVM入侵检测分类算法. 异常数据包在被分类后, 会被传递给Suricata入侵检测引擎进行精确规则匹配; 最后为该入侵检测系统搭建物理实验环境, 经过测试, 本文中的交-直-交变频矢量控制模型仿真结果动态性能良好, 与实际矢量控制系统参数的波形变化趋势相近. 通过抽取KDD Cup99测试数据集中的一部分对该入侵检测系统实施DOS攻击、R2L、U2R以及PROBING攻击行为, 验证该入侵检测系统的有效性.      

同步电动机调速控制系统矢量控制分析

介绍了煤矿主井提升机电控系统的概况,阐述了矢量控制基本概念、基本原理,就煤矿提升机同步电动机调速系统的矢量控制部分进行了分析研究。     

The psychological costs of chance over choice in reproduction.

Comments on an article by W. B. Miller (see record 1984-17604-001) that asserts that humans have moved from a passive adaptation to an active regulation of reproduction. Although Miller addressed the psychological sequelae of increasing control over reproduction, it is argued that he oversimplified the psychological contingencies of perceived high choice in reproduction. Some of the more recent technological advances appear to facilitate choice while only nominally increasing the chance of conception. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The malaria parasite, Plasmodium falciparum, increases the frequency of multiple feeding of its mosquito vector, Anopheles gambiae

It has often been suggested that vector-borne parasites alter their vector's feeding behaviour to increase their transmission, but these claims are often based on laboratory studies and lack rigorous testing in a natural situation. We show in this field study that the malaria parasite, Plasmodium falciparum, alters the blood-feeding behaviour of its mosquito vector, Anopheles gambiae s.l., in two ways. First, mosquitoes infected with sporozoited, the parasite stage that is transmitted from the mosquito to a human, took up larger blood meals than uninfected mosquitoes. Whereas 72% of the uninfected mosquitoes had obtained a full blood meal, 82% of the infected ones had engorged fully. Second, mosquitoes harbouring sporozoites were more likely to bite several people per night. Twenty-two per cent of the infected mosquitoes, but only 10% of the uninfected mosquitoes, contained blood from at least two people. We conclude that the observed changes in blood-feeding behaviour allow the parasite to spread more rapidly among human hosts, and thus confirm that the parasite manipulates the mosquito to increase its own transmission.     

Laparoscopic repair of perforated duodenal ulcers with a falciform ligament patch

This study examined field populations of Culiseta melanura for evidence of partial blood meals and multiple feeding behavior. Engorged specimens that had 1/3 or less abdominal distention together with eggs in stage I-II of ovarian development were recorded as mosquitoes that had taken partial blood meals. Multiple blood meals were credited to engorged specimens with fresh blood as well as partially digested blood surrounded with separate peritrophic membranes and eggs in stage III or IV of ovarian development. Results indicated that only 17 of 532 Cs. melanura were captured with a partial meal, indicating that natural populations feed to repletion more than 95% of the time. Less than 1% of the specimens showed physical evidence of feeding on multiple hosts. Culiseta melanura appears to be highly efficient at obtaining a full blood meal and seems to be extremely reluctant to refeed once ovarian development has been initiated. As a result, multiple feeding does not appear to be important in the amplification of virus by this species.     

The role of the beta-adrnergic receptor in the secretion of gastrin: studies in normal subjects and in patients with duodenal ulcers

Intravenous infusion of isoproterenol, a beta-adrenergic receptor stimulatory agent, increased serum gastrin concentration significantly more in patients with a duodenal ulcer than in healthy subjects. The rise in pulse rate, blood glucose concentration and in serum insulin was the same in both groups of subjects. Gastrin secretion was also increased significantly more in the patients than in the control subjects after a beef-meal. Basal serum gastrin concentrations were higher in the patients than in the control subjects and correlated to the rise in serum gastrin during both tests in the patients with a duodenal ulcer. Isoproterenol and meal stimulated gastrin secretion, expressed as percent of the basal value, were twice as higher in the patients as in the control subjects. The combined administration of isoproterenol and the meal had an additive effect on the rise in serum gastrin. Isoproterenol stimulated gastrin secretion was completely suppressed by propranolol, a beta-adrenergic receptor blocking agent, which had no effect on meal stimulated gastrin secretion. It is concluded that the mechanism of the hypersecretion of gastrin in patients with a duodenal ulcer did not involve a specific abnormality of the beta-adrenergic receptor or the receptor which recognized proteins and their digested products. There is no established role of beta-adrenergic receptor activity in the hypersecretion of gastrin in patients with duodenal ulcers. It is suggested that the beta-adrenergic receptor may have some yet unknown function unrelated to the acute secretory response of gastrin.     

T-cell regulation in murine and human autoimmune diabetes: the role of TH1 and TH2 cells

Insulin-dependent diabetes mellitus (IDDM) results from the destruction of pancreatic insulin-secreting cells by a T-cell-mediated autoimmune reaction. Distinct types of T helper cells (TH1 and TH2) have been characterised based on their cytokine secretion profiles following activation. Evidence from animal models favours the hypothesis that autoimmune diabetes is a TH1 response. However, there is no clear indication that a primary imbalance between protective TH2 and deleterious TH1 cells at early stages can trigger the autoimmune process. Protective CD4 + cells detected in nondiabetic young non-obese diabetic mice have not been shown to work through TH2 cytokines. In humans, there is little evidence that IDDM results from a TH1 response. Indeed, efficient experimental systems are lacking in humans to study the regulation of the autoimmune response in vitro. Interestingly, several immunotherapy strategies have aimed at inducing a TH2 response, even though TH2 cells have not been implicated in spontaneous disease development. However, recent ongoing trials in humans using oral administration of insulin to prevent diabetes are based on a protective mechanism which seems to depend essentially on transforming growth factor-beta. This cytokine is not dependent on TH1/TH2 dichotomy. Thus, although several attempts have been made to induce a TH1/TH2 switch to obtain a protective effect, a different and more complex mechanism probably (and paradoxically) accounts for the oral protection actually tested in animal models and humans.     

Biology and control of tabanids, stable flies and horn flies

Tabanids are among the most free-living adult flies which play a role as livestock pests. A single blood meal is used as a source of energy for egg production (100-1,000 eggs per meal), and females of certain species can oviposit before a blood meal is obtained (autogeny). Therefore, the maintenance of annual populations requires successful oviposition by only 2% of females. Wild animal blood sources are usually available to maintain annual tabanid populations. Larval habitats are also independent of domestic livestock. Thus, the use of repellents or partial repellents is the only effective chemical strategy to reduce the incidence of tabanids on livestock. Permanent traps (and possibly treated silhouette traps) can be employed to intercept flies. Selective grazing or confinement can also reduce the impact of tabanids. Stable fly adults are dependent on vertebrate blood for survival and reproduction, but the amount of time spent in contact with the host is relatively small. Stable fly larvae develop in manure, spilled feed and decaying vegetation. Management of larval habitats by sanitation is the key to stable fly control. Treatment of animals with residual insecticides can aid in control; thorough application to the lower body parts of livestock is important. Proper use of modified traps, using either treated targets or solar-powered electrocution grids, can be effective in reducing stable fly populations. Adult horn flies spend the major part of their time on the host, and the larvae are confined to bovid manure. Therefore, almost any form of topical insecticide application for livestock is effective against horn flies, in the absence of insecticide resistance. Treatments should be applied when economic benefit is possible; economic gains are associated with increased weaning weights and weight gains of yearling and growing cattle. Oral chemical treatments (insect growth regulators or insecticides) administered at appropriate rates via bolus, water, food or mineral mixtures can inhibit horn fly larval development. However, adult horn fly movement among cattle herds limits the use of larval control for horn fly population management. The augmentation of native parasites, predators and competitors has been attempted and even promoted for horn fly and stable fly control, but evidence for the success of such programmes is equivocal.     

Electrophysiological evidence for task effects on semantic priming in auditory word processing

A large-scale trial investigated the possibility of eradicating G.m.centralis from a traditional cattle rearing area using odour-baited targets at a reduced overall target density from 4 to 0.5-2.3 per km2, thus cutting down initial material costs by about 50%. Only the periphery of what was thought to be prime tsetse habitat (dense woodland) was treated with targets. These were all black or blue/black cloth (1.8 x 1 m), sprayed with deltamethrin suspension concentrate and baited with butanone and/or acetone (40-130 mg/h) and 1-octen-3-ol (0.5 mg/h). Although fly catches from traps and flyrounds initially dropped by approximately 3% per day and trypanosomiasis cases declined by 99% within a year, eradication was not achieved, so that more targets were deployed at a later stage. Although initially cheaper, the option of using reduced target densities proved financially unattractive because of prolonged periods of target maintenance prior to eradication. Revised strategies for tsetse control with odour-baited, insecticide-impregnated targets in west Zambia are presented.     

Application of gene therapy to treat age-related loss of dopamine D2 receptor

We have investigated the feasibility of using gene therapy to attenuate the age-related decline in striatal dopamine D2 receptors (D2R) associated with reduced motor control. To this end, we have constructed an adenoviral vector containing the cDNA for the rat D2R. When injected into HeLa and HS24 cells in vitro, the vector induced an abundant message for D2R, as demonstrated by Northern analysis, and produced a membrane-bound protein capable of binding a D2R ligand, [3H]spiperone. When injected into rat striatum in vivo, the vector produced a marked increase in D2R near the site of injection, as evidenced by increased [3H]spiperone binding as well as by another more specific ligand, [125I]iodosulpride. The D2R produced in the striatum were functional, as evidenced by rotational behavior induced by a subcutaneous injection of the dopamine agonist, apomorphine. However, we did not observe any significant improvement in motor performance during preliminary experiments in which aged rats received bilateral striatal injections of the vector. In young rats, vector-induced expression of D2R in striatum was increased markedly three to five days after infection, but then declined to baseline levels by day 21. Loss of expression in aged rats proceeded at a somewhat lower rate. Because of the loss of expression and lack of significant performance enhancement in aged rats following vector injection into the striatum, we are now pursuing other strategies. These include functional assessment of the current vector in D2R null mutant mice as well as construction of new vectors that may yield more long-term expression.