Geomagnetic field effect on cardiovascular regulation

The goal of the present research was try to explain the physiological mechanism for the influence of the geomagnetic field (GMF) disturbance, reflected by the indices of the geomagnetic activity (K, K(p), A(k), and A(p) indices), on cardiovascular regulation. One hundred forty three experimental runs (one daily) comprising 50 min hemodynamic monitoring sequences were carried out in rabbits sedated by pentobarbital infusion (5 mg/kg/h). We examined the arterial baroreflex effects on the short term blood pressure and heart rate (HR) variabilities reflected by the standard deviation (SD) of the average values of the mean femoral arterial blood pressure (MAP) and the HR. Baroreflex sensitivity (BRS) was estimated from blood pressure/HR response to intravenous (i.v.) bolus injections of vasoconstrictor (phenylephrine) and vasodilator (nitroprusside) drugs. We found a significant negative correlation of increasing GMF disturbance (K(p)) with BRS (P = 0.008), HR SD (P =0.022), and MAP SD (P = 0.002) signifying the involvement of the arterial baroreflex mechanism. The abrupt change in geomagnetic disturbance from low (K = 0) to high (K = 4-5) values was associated with a significant increase in MAP (83 +/- 5 vs. 99 +/- 5 mm Hg, P = 0.045) and myocardial oxygen consumption, measured by MAP and HR product (24100 +/- 1800 vs. 31000 +/- 2500 mm Hg. bpm, P = 0.034), comprising an additional cardiovascular risk. Most likely, GMF affects brainstem and higher neural cardiovascular regulatory centers modulating blood pressure and HR variabilities associated with the arterial baroreflex.     

Molecular detection of Bartonella species infecting rodents in Slovenia

Rodents, collected in three zoogeographical regions across Slovenia, were tested for the presence of bartonellae using direct PCR-based amplification of 16S/23S rRNA gene intergenic spacer region (ITS) fragments from splenic DNA extracts. Bartonella DNA was detected in four species of rodents, Apodemus flavicollis, Apodemus sylvaticus, Apodemus agrarius and Clethrionomys glareolus, in all three zoogeographic regions at an overall prevalence of 40.4%. The prevalence of infection varied significantly between rodent species and zoogeographical regions. Comparison of ITS sequences obtained from bartonellae revealed six sequence variants. Four of these matched the ITS sequences of the previously recognized species, Bartonella taylorii, Bartonella grahamii, Bartonella doshiae and Bartonella birtlesii, but one was new. The identity of the bartonellae from which the novel ITS sequences was obtained were further assessed by sequence analysis of cell division protein-encoding gene (ftsZ) fragments. This analysis demonstrated that the strain is most likely a representative of possible new species within the genus.     

Geomagnetic field modulates artificial static magnetic field effect on arterial baroreflex and on microcirculation

Spreading evidence suggests that geomagnetic field (GMF) modulates artificial magnetic fields biological effect and associated with increased cardiovascular morbidity. To explore the underlying physiological mechanism we studied 350 mT static magnetic field (SMF) effect on arterial baroreflex-mediated skin microcirculatory response in conjunction with actual geomagnetic activity, reflected by K and K _p indices. Fourteen experiments were performed in rabbits sedated by pentobarbital infusion (5 mg/kg/h). Mean femoral artery blood pressure, heart rate, and the ear lobe skin microcirculatory blood flow, measured by microphotoelectric plethysmogram (MPPG), were simultaneously recorded before and after 40 min of NdFeB magnets local exposure to sinocarotid baroreceptors. Arterial baroreflex sensitivity (BRS) was estimated from heart rate/blood pressure response to intravenous bolus injections of nitroprusside and phenylephrine. We found a significant positive correlation between SMF-induced increase in BRS and increment in microvascular blood flow (ΔBRS with ΔMPPG, r=0.7, p<0.009) indicated the participation of the arterial baroreflex in the regulation of the microcirculation and its enhancement after SMF exposure. Geomagnetic disturbance, as opposed to SMF, decreased both microcirculation and BRS, and counteracted SMF-induced increment in microcirculatory blood flow (K-index with ΔMPPG; r _s=−0.55, p<0.041). GMF probably affected central baroreflex pathways, diminishing SMF direct stimulatory effect on sinocarotid baroreceptors and on baroreflex-mediated vasodilatatory response. The results herein may thus point to arterial baroreflex as a possible physiological mechanism for magnetic-field cardiovascular effect. It seems that geomagnetic disturbance modifies artificial magnetic fields biological effect and should be taken into consideration in the assessment of the final effect. An erratum to this article can be found at     

Models and detection of spontaneous recurrent seizures in laboratory rodents

Epilepsy,characterized by spontaneous recurrent seizures (SRS),is a serious and common neurological disorder afflicting an estimated 1％ of the population worldwide.Animal experiments,especially those utilizing small laboratory rodents,remain essential to understanding the fundamental mechanisms underlying epilepsy and to prevent,diagnose,and treat this disease.While much attention has been focused on epileptogenesis in animal models of epilepsy,there is little discussion on SRS,the hallmark of epilepsy.This is in part due to the technical difficulties of rigorous SRS detection.In this review,we comprehensively summarize both genetic and acquired models of SRS and discuss the methodology used to monitor and detect SRS in mice and rats.     

Seroepidemiology of spotted fever group rickettsiae in small field rodents in Japan.

To clarify the geographic distribution of spotted fever group (SFG) rickettsiae in Japan, small field rodents captured in endemic and nonendemic areas were screened for anti-SFG rickettsia antibodies by the immunofluorescence test. Among total 716 specimens tested, 73-75% of rodents were antibody-positive against Rickettsia japonica and/or Rickettsia montana, showing different degree of antibody-positive proportions among each species of the rodents. Interestingly, these profiles were not different in the rodents from each endemic and nonendemic areas, indicating that the SFG rickettsiae are prevailing in the wider areas where patients have not been found yet.     

Modification of the anal tape method for detection of pinworms in rodents

A modification of Graham's anal tape technique for detection of oxyurid worm eggs involves a coverslip or microscope slide covered with a thin layer of adhesive. The worm eggs stick to the adhesive and can be directly observed under the microscope.     

Microhabitat choice and diet of rodents in Maynugus irrigation field, northern Ethiopia

An ecological study on the choice of microhabitat and diet of small mammals was carried out in Maynugus irrigation field of the Tigray region in northern Ethiopia. Abundance of rodents was high during the reproductive phase of the agricultural plants. Mastomys erythroleucus occurred more frequently in vegetable fields, whereas Arvicanthis dembeensis was more frequent in habitats with monocot plants. Scrotal males and reproductive females consumed more food by weight than abdominal males and quiescent females. Arvicanthis dembeensis consumed more food than M. erythroleucus. Both the species consumed more food during the main rainy season. All the cultivated plants were attacked by these rodents with a degree of difference in relation to season, species, sex, age and sexual condition. As rodent attack was more intense during the fruiting phase of the plants, rodent control management should be carried out during the flowering phase.     

The unique role of rodents in the detection of possible human carcinogens and mutagens

Some of the probable reasons underlying the observation that not all chemicals shown to be genotoxic in vitro are capable of eliciting tumours in rodents or humans are discussed using appropriate examples. It is suggested that a substantial proportion of the resources currently available for conducting rodent carcinogenicity bioassays should be employed in the short-term evaluation in vivo of some of the many hundreds of chemicals recently defined as genotoxic in vitro, rather than in the protracted evaluation of a few chemicals, often of unknown activity in vitro, for carcinogenicity. A decision tree approach to the evaluation of chemicals for human mutagenic/carcinogenic potential is presented which is at variance with the construction and philosophy of many of the current legislative guidelines. The immediate need for the adoption of one of the available short-term in vivo liver assays, and/or the development of a short-term in vivo rodent assay capable of concomitantly monitoring different genetic end-points in a range of organs or tissues is emphasized.     

PCR-测序法对啮齿类动物汉坦病毒的检测和基因分型

目的探讨PCR-测序法在啮齿类动物汉坦病毒临床检测中的应用价值。方法以Genbank 7种血清亚型24株汉坦病毒代表性毒株为基础,从病毒基因S片段序列设计引物,采用邻位相连法进行系统进化分析,以该方法对浙江省近年从野生啮齿类动物中临床分离的汉坦病毒毒株进行分型鉴定。结果所建系统发育树将所分析的毒株分为5个区域,引起HFRS的四种血清型具有较稳定的拓扑结构,且能与引起HPS的血清型进行区分。11株实验毒株进行PCR扩增和测序,结果表明该引物具有高度的敏感性和特异性,其中9株浙江省分离的血清型未知毒株的系统发育分析发现其包含引起HFRS的3株HTN和1株SEO血清型,其他5株属两种未知血清型。讨论所建立的PCR-测序法具有用于临床检测汉坦病毒的价值。     

Ketamine-medetomidine anesthesia with atipamezole reversal: practical anesthesia for rodents under field conditions

Field studies often necessitate immobilization of animal subjects, but field conditions may complicate the induction of anesthesia. Likewise, researchers must ensure that animals are fully recovered before releasing them. The authors successfully tested an anesthesia induction and reversal regimen under field conditions.     

探讨监测传粉者的方法

种子植物的有性生殖依赖于花粉传递, 传粉者是花粉传递的媒介。传粉者为野生植物和农作物提供的传粉服务, 是我们绿色星球最重要的生态过程之一, 在维持生物多样性和农作物生产方面具有重要作用。农业集约化、生境破碎、全球气候变暖等因素加剧了传粉者衰减和灭绝的风险, 对生态系统的功能和农业生产造成了不利影响。为了维系植物与传粉者生态互作关系的稳定性, 人们建立了一系列从局部地区到国际、由普通民众到科研人员参与的传粉者监测项目, 以期掌握传粉生态系统的状况和发展趋势, 为自然和农业生态系统的健康提供预警和反馈。本文强调了监测传粉者的首要前提条件, 即正确区分传粉者和访花者; 总结了监测传粉者的直接和间接方法, 包括群落水平的直接观察监测, 以及利用关联数据进行间接推断与调查; 介绍了具有潜力的由大众参与的公众监测项目。针对7种常见传粉者类群, 讨论了可行的适用于各类群的监测方法, 为监测拓展到更多的传粉者类群提供了可能。期望能为生物多样性的保护、传粉者动态的精准监测提供建议与参考。     

Electric field detection in sawfish and shovelnose rays

In the aquatic environment, living organisms emit weak dipole electric fields, which spread in the surrounding water. Elasmobranchs detect these dipole electric fields with their highly sensitive electroreceptors, the ampullae of Lorenzini. Freshwater sawfish, Pristis microdon, and two species of shovelnose rays, Glaucostegus typus and Aptychotrema rostrata were tested for their reactions towards weak artificial electric dipole fields. The comparison of sawfishes and shovelnose rays sheds light on the evolution and function of the elongated rostrum ('saw') of sawfish, as both groups evolved from a shovelnose ray-like ancestor. Electric stimuli were presented both on the substrate (to mimic benthic prey) and suspended in the water column (to mimic free-swimming prey). Analysis of around 480 behavioural sequences shows that all three species are highly sensitive towards weak electric dipole fields, and initiate behavioural responses at median field strengths between 5.15 and 79.6 nVcm(-1). The response behaviours used by sawfish and shovelnose rays depended on the location of the dipoles. The elongation of the sawfish's rostrum clearly expanded their electroreceptive search area into the water column and enables them to target free-swimming prey.