猪附红细胞体电镜特点及药物治疗效果的电镜观察

近年来,国内外很多关于猪附红细胞体病诊断与防治的文章,但对猪附红细胞体本身形态学报道的文章却很少.本实验对猪附镜下的各形态、大小以及感染强度作了较详细的描述.球形、环形、圆盘形为E.suis的主要形态,体形较大的E.suis以芽苞生殖进行繁殖,感染强度随着病情的发展而呈现波浪形态变化.对致病机制作了进一步的阐述,在急性阶段,附红细胞体病会引起由一种经冷凝素IgM来介导的或与之相关的自身免疫溶血性贫血.最终结合电镜观察临床药物治疗效果,长效土霉素、贝尼尔在防治猪附红体病有一定的疗效.     

Regulation of DNA synthesis in Leydig cells obtained from neonatal pig testes.

Three distinct waves of Leydig cell development are found in the pig testes, which occur during fetal, perinatal, and prepubertal periods. Proliferation of Leydig cells is primarily regulated by luteinizing hormone (LH); however, effects of LH on proliferation of immature rat Leydig cells are mediated by specific growth factors and cytokines such as transforming growth factor-alpha (TGFalpha), insulin-like growth factor-1 (IGF-1), interleukin-1beta (IL-1beta), steroidogenesis-inducing protein (SIP), and TGFbeta. The objective of the present study was to identify growth factors that could possibly be involved in the proliferation of Leydig cells in the neonatal pig testis. Leydig cells were isolated from 3- to 5-d-old pig testes, cultured for 48 hr in serum-free media, washed, and treated with hCG and/or IGF-1, epidermal growth factor (EGF), IL-1beta, SIP, and TGFbeta for 18 hr. Tritiated thymidine incorporation into DNA was assessed over a subsequent 4-hr period. Incorporation of [3H]-thymidine was stimulated by hCG treatment with a 2.3-fold increase over control cultures. SIP also induced a significant increase (P < 0.0001) in the incorporation of [3H]thymidine into Leydig cell DNA. Similarly, EGF and IGF-1 also increased DNA synthesis in neonatal porcine Leydig cells, whereas IL-1beta had no effect. TGFbeta had very little, if any, effect on DNA synthesis when added alone, but inhibited the stimulatory effects of other mitogens (SIP, hCG, EGF/TGFalpha, and IGF-1). Our results indicate that these growth factors may play a role in the LH/hCG-dependent proliferation of Leydig cells during the perinatal period of development.     

The DNA of an IPV strain of bovid herpesvirus 1 in sacral ganglia during latency after intravaginal infection

Two calves were inoculated intravaginally with a strain of bovid herpesvirus type 1 (BHV-1, IBR/IPV) isolated from a cow with infectious pustular vulvovaginits (IPV). The animals were killed during a latent stage of infection as characterized by seroconversion, absence of virus shedding and recrudescence of virus shedding after dexamethsone treatment.IPV-virus DNA was detected in 9 out of 20 sacral ganglia of the 2 calves. Of the sections, 7.2% (n = 250) contained 1 cell with IPV-virus DNA, which was restricted to the nucleus of neurons. In agreement with findings on herpes simplex virus infections, the viral DNA of BHV-1 is harbored in the local sensory ganglia.Virological and serological implications of the latent IPV infection are discussed.     

The vascular bed in the rabbit ear: microangiography and scanning electron microscopy of vascular corrosion casts

The vascular bed of the rabbit ear has been studied with light microscopy, microangiography and scanning electron microscopy of resin casts in a series of 20 ears. The major arteries supplying the ear were the central and rostral auricular branches of the caudal auricular artery. The caudal auricular branch was not observed, except as a small vessel supplying the rostral auricular base. The central auricular branch supplied blood to most of the auricular integument and was surrounded by capillaries extended from those supplying the skin. The periarterial capillaries formed a fine, compact network in the tunica media and were closely related to the central auricular branch. Evidence is presented suggesting that this vascular mechanism has a counter-current heat-exchange function for regulating body temperature. The artery had the well-developed internal elastic lamina and intimal cushions that regulate blood flow at the branching sites. A number of arteriovenous anastomoses were also observed between arterioles and venules, particularly in marginal regions of the ear. The intimal cushions and arteriovenous anastomoses might play an additional role in thermoregulation by regulating local blood flow in the ear.     

Detection of antibodies in sera of weaned pigs after contact infection with Sarcoptes scabiei var. suis and after treatment with an antiparasitic agent by three different indirect ELISAs

Three commercial enzyme-linked immunosorbent assays (ELISAs) were compared for the detection of antibodies to Sarcoptes scabiei var. suis using experimental sera of six 8-week-old pigs after contact infection with Sarcoptes scabiei var. suis. Six non-infected pigs were monitored as a control group. Blood sera were taken once a week from all animals. After successful infection the pigs were treated with an antiparasitic agent (12 weeks post infection (p.i.)) and the antibody titres were monitored until they were negative. The antibody levels of the experimental pigs reached the cut-off level 5 weeks after introduction of an infected animal to the group and were positive by both the Sarcoptes-ELISA 2001 PIG and the Acar-Test P-ELISA. Four weeks after treatment mean results showed optical densities (% OD) below the cut-off level in the Sarcoptes-ELISA 2001 and 8 weeks after treatment in the Acar-Test P-ELISA. In the Chekit Sarcoptest pigs had elevated antibody levels in comparison to control animals, but ODs remained below the given cut-off level at all times. In a second examination with Chekit Sarcoptest (different lot) and at a lower cut-off level, the sera of most of the piglets tested positive. Eight weeks after treatment, four from six pigs still had positive OD values. Therefore this investigation showed a higher sensitivity for the Sarcoptes-ELISA 2001 and the Acar-Test P-ELISA than for the Chekit Sarcoptest. Different test sensitivities must be considered when serologic methods are used for the diagnosis of swine sarcoptic mange, especially for monitoring and controlling eradication programs.     

Comparison of pig, rabbit and mouse IgG response to Streptococcus suis serotype 2 proteins and active immunization of mice against the infection.

The aim of this study was to compare the IgG response of different animal species to Streptococcus suis serotype 2 proteins and to evaluate the immunogenic potential of these proteins in the mouse experimental model of infection. The protein profiles of ten different S. suis capsular type 2 isolates were compared by Western blotting using antisera produced in mice, rabbits and pigs against the reference strain. Strains were grown overnight in Todd-Hewitt broth, harvested by centrifugation, processed in a French press cell and digested with lysozyme. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was then performed and proteins transferred to nitrocellulose. The rabbit antiserum recognized seventeen common immunoreactive proteins, of which, proteins of 33, 44, 96, 122 kDa were present in all strains. Two, 128 and 136 kDa proteins were recognized by swine serum in many strains. An additional protein of 30 kDa was recognized by the mouse antiserum. These seven proteins, originating from the reference strain, were excised directly from polyacrylamide gels, mixed with incomplete Freund's adjuvant and given to groups of five mice on days 0 and 10. Immunoglobulin G response to each protein was monitored on day 20 using Western blots. Mice were then experimentally infected on day 21. Results indicated that vaccination with proteins of 33, 44, 128 and 136 kDa resulted in an IgG response and protection against the challenge with the reference strain, but gave only a partial protection against another virulent S. suis serotype 2 strain.     

Demonstration of equine infectious anemia virus in primary leukocyte cultures by electron microscopy.

Electron microscopy was used to demonstrate the presence of viral particles in primary cultures of leukocytes taken from a horse after SC inoculation with the Wyoming strain of equine infectious anemia virus. Unlike previous studies, the exposure virus was not passaged through cell culture prior to horse inoculation. Cultures were begun approximately 1 week before and 1 week after the 1st pyrexic period after inoculation. In both samples, viral particles and cytoplasmic alterations were observed resembling those previously reported in equine infectious anemia virus and other retravirus-infected cells.     

Differentiation of Toxocara canis and T. cati eggs by light and scanning electron microscopy

In this study, we investigated the morphological identification of Toxocara canis and T. cati eggs on the basis of light and scanning electron microscopic (SEM) observations. T. canis and T. cati eggs used in this study were recovered from the uteri of respective gravid female worms. Measurement of egg size was not helpful in the differentiation of these species, because approximately 90% of eggs measured were of similar size. Using SEM, we were able to differentiate T. canis eggs from T. cati eggs based on their respective characteristic surface structures. Both species have subspherical eggs with markedly pitted surfaces like those of a golf ball, but the surface pitting in T. canis is more coarse than that in T. cati. In this study, however, these differences were not absolute, as 16% of T. canis and 29% of T. cati eggs showed surface pitting that was uncharacteristic of their species. Of the 16% of T. canis eggs that could not be differentiated by surface structure, 3% had pitting resembling T. cati, and the remaining 13% showed intermediate type surface pitting. Similarly, 5% of T. cati eggs resembled T. canis, and 25% of these were of intermediate type. Light microscopic observation yielded results similar to those of SEM, indicating that light microscopy is also a useful tool for the identification of Toxocara eggs.     

Scanning electron microscopy of the cecal mucosa in Eimeria-tenella-infected and uninfected chickens.

Four major types of surface conformation were observed in the ceca of uninoculated control chickens. Spatulate villi were found in the cecal neck region, low ridges in the region where the neck expands, protruding collarlike structures in the mid cecal pouch, and flattened collars in the distal portion. In ceca infected with Eimeria tenella, there was some erosion and sloughing of the mucosal cells. These lesions were slight in the neck region, more severe in the dilated portion, most severe in the midregion, and moderate in the distal area. Oocysts were observed in the mucosal tissue of the cecal pouch.     

Renal myxozoanosis in crowned river turtles Hardella thurjii: description of the putative agent Myxidium hardella n. sp. by histopathology, electron microscopy, and DNA sequencing

Chelonian myxozoanosis is rarely reported and has previously not been documented to cause disease. This report describes myxozoanosis associated with significant renal disease in two Crowned River turtles (Hardella thurjii). One turtle presented with emaciation and died. The cage mate presented with emaciation and was euthanized. Histologically, renal intratubular myxozoan spores were associated with renal tubular necrosis, tubular mineralization, and chronic interstitial nephritis, with membranoproliferative and mes-angioproliferative glomerulopathy. Both turtles also had disseminated metastatic mineralization. On the basis of these findings, chronic renal insufficiency from myxozoanosis and subsequent metastatic mineralization were considered the primary problems. By light and electron microscopy, the myxozoan spores had features of the genus Myxidium. Maximum parsimony analysis of small-subunit rDNA sequences placed the turtle myxozoan basal to a clade containing Myxidium truttae and a Myxidium sp. with strong bootstrap support. This myxozoan agent appears to be a significant pathogen in H. thurjii on the basis of morphologic changes in the kidneys of in the infected turtles.     

Subjective vs. objective analysis of the corneal endothelial cells in the rabbit cornea by scanning electron microscopy - a comparison of two different methods of corneal fixation

OBJECTIVE: To illustrate a method of quantitative scanning electron microscopy (SEM) for the evaluation of the corneal endothelia of small animals by comparing two commonly used fixation methods. ANIMALS STUDIED: Female New Zealand white rabbits, aged 10-12 weeks. PROCEDURES: The corneas were either dissected from the eye and placed in fixative (2% glutaraldehyde in 80 mm cacodylate, pH 7.4) or the whole eyeball immersed in fixative solution and the cornea dissected later. Lower (x 200) and high magnification (x 1,000-5,000) images were inspected for overall appearance. Magnification images (x 500) were used to measure the areas of 100 cells, and cell density (CD) calculated from the average area. RESULTS: Both fixation protocols yielded an intact endothelial surface, but the dissect- then-fix protocol resulted in more creasing and distortion artifacts that were avoided with the whole-eyeball fixation. Overall, the CD values were higher if the dissect-then-fix method was used, and the uniformity of the cell mosaic was less. The median CD values for the central, mid-peripheral and peripheral regions following dissect-then-fix protocols were 7,693, 7,353, and 7,071 cells/mm(2) (average eight corneas at each location). If the whole-globe fixation was used, the median CD values were 6,098, 5,747, and 4,785 cells/mm(2). CONCLUSION: Cell density values in SEM can be very different according to the fixation method used. A distinct regional difference in CD was evident, which was more pronounced if the cornea was fixed prior to being dissected from the eye.