Atypical Histoplasma capsulatum infection in a dog

Disseminated histoplasmosis was diagnosed in a 10-year-old dog suspected of having hepatic carcinoma. Clinical abnormalities included diffuse hepatomegaly, gastrointestinal bleeding, thoracic and abdominal effusion, anemia, leukocytosis, and thrombocytopenia. Histoplasmosis characteristically is a disease of the mononuclear phagocyte system, but in this case was diagnosed by finding Histoplasma capsulatum organisms in neutrophils on the blood smear.     

Active bleb formation is abated in Lytechinus variegatus red spherule coelomocytes after disruption of acto‐myosin contractility

Red spherule coelomocytes are immune cells in the sea urchin Lytechinus variegatus that have been characterized as motile O₂ transport cells. Video microscopy of living red spherule coelomocytes reveals a constitutive, dynamic array of cellular morphologies and movements. Cells continuously send out and retract membrane blebs all over the cell surface as part of their normal cellular physiology. Disruption of microtubules by perfusion with either nocodazole or taxol had no effect on bleb formation or motility. Perfusion with cytochalasin B abated bleb formation and revealed cells that exhibited multiple small spheres attached by short membrane extensions. Attenuation of blebbing and intracellular organelle motility were restored by washing out with cytochalasin B. Treatment with phalloidin also abated bleb formation and revealed a smooth, spherical cellular morphology. The effects of phalloidin were completely reversible after washout. Red spherule coelomocytes treated with blebbistatin rounded up with an irreversible retraction of blebs into surface blebs that were greatly reduced in size, number and motility. Normal cell surface bleb formation and intracellular organelle motility were not restored after washout of the drug. These results indicate that the acto‐myosin contractile mechanism contributes to the dynamics of constitutive cell surface membrane blebbing in invertebrate immune cells.     

家蚕滞育卵中酯酶A_4的生理作用研究

家蚕卵中酯酶A_4与滞育发育具有密切的关系。研究表明:此酶具有较低的水解专一性,是一种广泛作用于生物体内各种酯键的酶。酯酶A_4能水解结合型胆甾醇的酯键,并且其活性表现与滞育发育的时间进程相一致。酯酶A_4对cAMP的水解作用表现为两个峰,而对cGMP的水解作用,在精制后第10—13日间活性高于其它时间,但变化较缓慢。     

Prevalence of Histophilus ovis and Actinobacillus seminis in the genital tract of sheep

Histophilus ovis and Actinobacillus seminis were isolated from the preputial cavity of 6-month-old rams and the vagina of 6-month-old ewes at a substantially higher rate than that in mature (greater than 2 years old) rams and ewes. These organisms appeared to be a transitory component of the ovine genital flora, the prevalence of which was associated with age regardless of gender. Additional evaluation of the recoverability of H ovis and A seminis from the preputial cavity of rams from birth to 1 year of age indicated that the isolation rate from rams and predominance of the organisms in the preputial cavity differed greatly over this age period. These organisms were not recoverable until ram lambs were 12 weeks of age and were most prevalent at 20 weeks of age, after which recoverability of H ovis and A seminis from the preputial cavity steadily decreased, continuing through the time of the last evaluation at 1 year of age. The time period with which these organisms can be isolated from the preputial cavity is closely correlated with the time period when epididymitis associated with these organisms develops, and may be an important factor in the pathogenesis of epididymitis.     

The effect of dietary energy level on the voluntary calorie intake of laying birds

This paper summarises evidence taken from the literature to show the effect of dietary energy level on the voluntary food intake of laying birds. Although groups of pullets offered different diets tend to adjust consumption so as to maintain the same calorie intake, this adjustment is imperfect in the majority of cases. Thus birds fed high energy diets usually “over‐consume” calories and gain more in weight than birds fed lower energy diets. The degree of over‐consumption observed when a particular strain is offered a range of diets of differing energy content is correlated with the characteristic calorie intake of that strain (r = 0.667). Strains with characteristically high energy intakes adjust their food consumption to compensate for differences in energy content of the diet less efficiently than the small strains which have characteristically low calorie intakes.

From the relationships demonstrated, a formula is developed which predicts the expected daily calorie intake for any level of dietary energy, given a knowledge of the calorie intake of the strain when fed some standard diet. The use of this information in the formulation of diets designed to minimise the cost of feeding is illustrated by an example.     

Growth of Serpulina (Treponema) hyodysenteriae under iron-restricted conditions.

Reference strains of Serpulina hyodysenteriae expressed at least three iron-regulated proteins with apparent molecular masses of > 200, 134, and 109 kDa when grown under iron-restricted conditions. Cells of S. hyodysenteriae grown under these conditions also showed increased outer membrane bleb formation when examined by electron microscopy after negative staining. S. hyodysenteriae did not use the 2 most common types of siderophore, namely catechol and hydroxamate. Western blotting with serum from a pig experimentally infected with S. hyodysenteriae B204 indicated that the 109-kDa major iron-regulated protein was expressed in vivo and was conserved among all strains tested.     

An ultrastructural study on the interaction of Mycoplasma gallisepticum with the chicken tracheal epithelium

Seven-day-old chickens wee intratracheally inoculated with Mycoplasma gallisepticum. The tracheas collected 6 and 14 days after chickens were inoculated were subjected to titration of mycoplasma and examination by light and electron microscopy. The mycoplasma organisms grew well; 10(7) to 10(8) color-changing units in a milligram of tissue were determined. Tracheal lesions occurred in close association with the presence of mycoplasmas and were characterized by degeneration of the epithelial cells and inflammatory cellular infiltration of the mucosa. Mycoplasmas were predominantly found extracellularly and only rarely in phagocytic vacuoles of the epithelial cells. Although the mycoplasmas exhibited considerable pleomorphism in size and shape, most of them were oval or round, and the largest diameters were between 300 and 700 mn. Elongated and irregular forms were also observed, particularly in those mycoplasmas adhering to the epithelial cells. The organism had a limiting unit membrane, the fibrillar nuclear area, the peripheral cytoplasmic area containing numerous ribosomes, and a terminal bleb structure. Mycoplasmas attached to the epithelial cells by their blebs close to the host cell membrane. At the attachment site, neither fusion of the membranes of the mycoplasma and host cell nor injury to the host cell membrane could be demonstrated. Nevertheless, seemingly, the intimate association between the adhering mycoplasmas and the epithelial cells might be an important factor in pathogenesis of the disease.     

Streptomyces sp., a cause of fistulous withers in donkeys

Four of 10 donkeys, which showed lesions simulating fistulous withers, were examined clinically with the aim to cultivate and identify the causal agent. Aspiated purulent materials were subjected to bacteriological examination. The causal organisms were recovered in Tryptic Soya agar medium when incubated aerobically at 37 degrees C for up to 5 days. These organisms were found to be actinomycetes-like, Gam positive with stable branching filaments and to form heavy aerial hyphae on colony surface. The isolated organisms ere tentatively identified as Streptomyces sp. on the basis of morphological and cultural characteristics. The initial sequences analysis of the 16S rDNA gene conformed that one of the isolates (SD551) falls within the phylogenetic clade, which encompasses the genus Streptomyces. Studies are underway to further describe the disease and its causal agent. The report represents a good evidence to incriminate Streptomyces in the aetiology of the fistulous withers.     

Polymorphonuclear leukocyte function in HIV-1-infected chimpanzees

The chemiluminescent characteristics of enriched populations of neutrophils from control and HIV-infected chimpanzees were assessed. Neutrophils from HIV-infected chimpanzees were suppressed in their ability to generate a normal response to particulate and soluble stimuli when compared to normal and hepatitis non-A, non B-infected controls. Particulate (latex beads) stimulation of neutrophils resulted in an aberrant response when contrasted with controls. Normal control responses were characteristically biphasic while the response from hepatitis NANB HIV-infected chimpanzees was not biphasic. Neutrophils challenged with a soluble (phorbol ester) stimulant also demonstrated a suppressed response. These data suggest that HIV infection has an additive suppressive effect on neutrophil function in chimpanzees previously infected with hepatitis NANB. The suppression of chimpanzee neutrophil function following HIV infection is similar to that seen in other non-primate viral and retroviral infections.     

Ehrlichia platys (Anaplasma platys) in dogs from Maracaibo,Venezuela: an ultrastructural study of experimental and natural infections

Since 1982 Ehrlichia platys, now emended as Anaplasma platys, has been diagnosed in dogs from Maracaibo, Venezuela, using buffy coat smears stained with Dip Quick. Three dogs were inoculated with an A. platys strain. When parasitemia reached 60-97%, blood samples obtained from the inoculated dogs and from two naturally infected dogs were centrifuged to obtain platelet-rich plasma, which was mixed with 0.1% glutaraldehyde at 37 C for 10 minutes. Platelet pellets were fixed in 3% glutaraldehyde for 72 hours and processed for conventional transmission electron microscopy. Platelets contained pleomorphic organisms with a distinct double membrane that was not observed when the bodies were in a determinate developmental stage. There were 1-15 individual bodies included in a host cell vacuole. The organisms had an electron-lucent inner area, whereas the internal surface of their inner plasma membranes exhibited an electron-dense rough substance. In naturally infected dogs, organisms with different ultrastructural features were found inside the same platelet. Some organisms contained central dense material surrounded by a pale zone, which was in turn surrounded by a moderately dense peripheral area. Other organisms contained an eccentrically electron-dense material. The intravacuolar space appeared fully electron-lucent. Each organism usually exhibited inner fine strands. Empty structures displaying junctions with the vacuolar membrane were observed. Our results indicate that distinct ultrastructural characteristics are associated with different stages of A. platys development and may differ among A. platys strains.     

Effects of tilmicosin treatment on Pasteurella haemolytica organisms in nasal secretion specimens of calves with respiratory tract disease

OBJECTIVE: To determine the effect of tilmicosin treatment on number of Pasteurella haemolytica (PH) organisms in nasal secretion specimens of calves with respiratory tract disease. ANIMALS: 206 British mixed-breed beef calves, 2 to 5 months old. PROCEDURE: In 2 separate studies of outbreaks, calves (study 1, n = 101; study 2, n = 105) that developed respiratory tract disease after transport to a feedlot were treated with tilmicosin. Nasal secretion specimens were examined for PH organisms to determine the status of colonization. RESULTS: In both studies, PH serotypes A1 and A6 were isolated. In study 1, tilmicosin treatment eliminated or markedly reduced the number of PH organisms in calves on days 1, 4, and 5 after treatment. In study 2, tilmicosin treatment eliminated PH organisms in calves on days 1, 2, 5, and 6 after treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Overall, tilmicosin treatment increased the number of culture-positive calves that became culture-negative and decreased the number of culture-negative calves that became culture-positive for up to 6 days after treatment. Tilmicosin treatment decreased the number of PH organisms in nasal secretion specimens, which indicated that fewer PH organisms were available to infect the lungs or to infect other calves. By reducing colonization, prophylactic use of tilmicosin before transport or at the time of arrival at a feedlot is likely to reduce the incidence of acute respiratory tract disease in calves for the initial several days after arrival, which is the period when they are most susceptible to infectious organisms.     

The detection of Mycobacterium paratuberculosis in bovine faeces by isolation and the comparison of isolation with the examination of stained smears by light microscopy

The detection of Mycobacterium paratuberculosis organisms in bovine faeces by isolation was compared with that by the microscopical examination of Ziehl-Neelsen stained faecal smears for the presence of clumps of acid-fast M. paratuberculosis organisms. Faeces were obtained from cattle naturally or experimentally infected with M. paratuberculosis as well as from uninfected cattle. Microscopical examination was an unreliable method for the detection of M. paratuberculosis organisms, since the organisms were only detected in 99 (=55.9%) of 177 culturally positive faecal samples. 1111 addition, clumps of acid-fast organisms indistinguishable from M. paratuberculosis were also observed iin three of 18 samples from cattle free from Johne's disease and in 18 of 37 culturally negative samples from paratuberculous cattle. When M. paratuberculosis organisms were added to faeces from an uninfected cow, results showed that isolation attempts should be positive when 15 or more M. paratuberculosis organisms per gram of faeces are present.     

Relative importance of Salmonella-specific antibody isotypes in phagocytosis of Salmonella typhimurium by ovine mammary neutrophils

The comparative opsonic efficiency of ovine salmonella-specific antibody isotypes was determined by measurement of specific phagocytic uptake of opsonised virulent Salmonella typhimurium by ovine mammary neutrophils. An in vitro phagocytosis assay revealed that IgM was superior to IgG2 in promoting the phagocytosis of opsonised virulent organisms. IgG1, on the other hand, was non-opsonic. Superiority of the IgM isotype over IgG2 as an opsonin was also evident in studies on the viability of opsonised S typhimurium upon phagocytosis. It was revealed that the percentage of organisms killed was appreciably greater when opsonisation was carried out with the IgM than with the IgG2 isotype, although after ingestion by neutrophils there was essentially no difference in the efficiency with which the ingested organisms were killed.     

Lens sparing pars plana vitrectomy and retinal transplantation in cats

Neuroretinal transplantation techniques have been evolving during recent years. Experiments in rodent models with degenerative retinal disease have been encouraging. This paper describes a surgical technique developed for use in the Abyssinian cat mutant. After two-port pars plana vitrectomy, retinotomy and bleb formation, whole sheets of neonatal neuroretinal allografts were placed into the subretinal space. The surgery was difficult but feasible, and the main complication was intraoperative hemorrhage.     

Conjunctival swab cytology from a guinea pig: it's elementary!

Three 3-month-old guinea pigs (Cavia porcellus) were evaluated for purulent ocular discharge. Conjunctival swabs were obtained for cytologic evaluation of Wright's-Giemsa-stained preparations. The specimen from the most severely affected guinea pig consisted primarily of karyolytic neutrophils and small lymphocytes. Epithelial cells occasionally were observed that contained intracytoplasmic coccoid basophilic organisms, 0.5-1.5 microm in diameter. The intraepithelial inclusions were most consistent with Chlamydia sp elementary and reticulate bodies. Specimens from the other 2 guinea pigs had a similar inflammatory response, but organisms were not observed. Polymerase chain reaction (PCR) analysis of a conjunctival swab from the most severely affected guinea pig was positive for C psittaci, which also is referred to as Chlamydophila caviae, immunotype 8, formerly known as the guinea pig inclusion conjunctivitis strain of C psittaci. Chlamydial conjunctivitis is a common problem in guinea pig populations, with C caviae being specific for this species. Cytologic identification of elementary or reticulate bodies within epithelial cells is diagnostic for the organism in Giemsa-stained preparations. However, PCR is an important complementary tool when organisms are not observed and for accurate classification of the Chlamydia species.     

Evidence of phenotypic dichotomy within an individual Pasteurella multocida type strain and among some haemorrhagic septicaemia-causing field isolates

Haemorrhagic septicaemia-causing strains of Pasteurella multocida were identified by a disease-specific ELISA. Some strains, however, were of the same serotype as those which cause haemorrhagic septicaemia (HS) but were negative when tested in the disease specific ELISA. The suspect false negative isolates were passaged in mice and retested in the HS ELISA with the same result. Immunoelectron microscopy was used to examine further these suspect HS-causing strains. Monoclonal antibodies and protein A-gold showed that the suspect negative organisms were a mixture of phenotypes with less than 10 per cent, and usually less than 2 per cent, of the population expressing HS-associated epitopes. The degree of staining on the organisms expressing the HS-epitopes was of the same intensity as the positive control organism. Expression of the HS-associated epitopes is presumably too low to allow detection in the current HS ELISA.     

Leprosy in a chimpanzee. Morphology of the skin lesions and characterization of the organism.

Microscopic features of lepromatoid lesions in a chimpanzee inoculated with bovine leukemia virus consisted of diffuse dermal infiltrations of foamy histiocytes, except for a subepidermal "clear zone" devoid of infiltrating cells. Acid-fast organisms were in histiocytes, dermal nerves and a branch of the left radial nerve. The organisms were more intensely acid-fast with the Fite-Faraco than with the Ziehl-Neelsen stain. The organisms did not oxidize 3,4-dihydroxyphenylalanine (dopa) to indole but their acid-fast staining quality was removed by pretreatment with pyridine. Human leprosy patients, inoculated simultaneously with chimpanzee and human lepromin, reacted similarly to both lepromins. Organisms, when inoculated into mouse footpads, multipllied in 6 months to a quantity that was compatible with their identification as Mycobacterium leprae.     

The epidemiology and pathogenic significance of haemonchosis in a merino flock in East Africa

The epidemiology of H. contortus was studied for 21 months in 80 set-stocked Merino ewes and their grazing in an endemic area in Kenya. Observations included faecal egg counts (weekly), worm burdens (monthly), haematological indices and clinical signs. The levels of infective larvae on the pasture were estimated using tracer sheep.The classical acute form of haemonchosis was seen with equal intensity in both ewes and lambs during periods of high rainfall and self-cure was confirmed as a flock phenomenon which occured simultaneously on one occasion in sheep of all ages.Not previously recognised were the uniformity of the faecal egg counts in both ewes and lambs over long periods when the worm burdens fluctuated greatly, the marked decrease in worm burdens without the occurence of classical self-cure during periods when the intake of infective larvae was low, and the inverse relationship between the individual worm-weight and the total worm population. It was also concluded that one of the most significant features of haemonchosis is not the acute syndrome so characteristically associated with the disease, but the fact that a moderate infection of a few hundred worms persisting over a period of several months will produce chronic anaemia and, ultimately, severe loss of bodily condition and deathes in ewes and lambs grazing on poor quality pasture.     

Evaluation of a scheme for predicting the gram-staining reaction of organisms causing bovine mastitis.

The accuracy of a scheme for predicting the gram-staining reaction of organisms causing bovine mastitis in cows with systemic signs of disease (anorexia) was evaluated over 1 year. Criteria for making the predictions included: season of year, stage of lactation, appearance of milk, detection and duration of teat injuries, and milk odor. It was possible to determine the cause by microbiologic culture of specimens from 136 of the 147 cows of the study. Of 78 infections caused by gram-negative (mostly coliform) organisms, 62 (79%) were predicted accurately to be caused by gram-negative organisms. Of 57 infections caused by gram-positive organisms, 45 (79%) were predicted correctly to be caused by gram-positive organisms. Correctly predicted as gram-positive organisms causing infection were: Actinomyces pyogenes in 20 of 21 (95%) cows; Staphylococcus sp in 14 of 22 (64%) cows; Streptococcus sp in 10 of 13 (77%) cows and Bacillus sp in 1 cow. Overall accuracy, in those instances when bacteria were isolated (136 cows), was 78%.     

Bacterial colonization of intravenous catheters in young dogs suspected to have parvoviral enteritis

OBJECTIVE: To determine the prevalence of bacterial colonization of IV catheters among young dogs suspected to have parvoviral enteritis, to identify the organisms responsible for catheter colonization, and to determine the antimicrobial susceptibility of organisms that were obtained. DESIGN: Case series. ANIMALS: 100 dogs. PROCEDURE: Catheters were aseptically removed when fluid therapy was discontinued, the catheter was replaced, or the dog died. The distal tip of the catheter was cut off, split open, and vortexed with sterile saline (0.9% NaCl) solution. The saline solution was plated on culture plates, which were then incubated and examined for bacterial growth every 24 hours for 72 hours. All bacteria cultured were identified, and antimicrobial susceptibility was determined. RESULTS: Bacteria were isolated from 22 catheters. Most bacteria that were isolated were of gastrointestinal tract or environmental origin (Serratia odorifera, S. liquefaciens, S. marcescens, Acinobacter anitratus, Citrobacter freundii, Klebsiella pneumoniae, K. oxytoca, Escherichia coli, Enterobacter spp). Only 2 gram-positive organisms were isolated (Staphylococcus intermedius and Streptococcus spp). High percentages of organisms were resistant to penicillin, lincomycin, cloxacillin, erythromycin, and cephalexin. Percentages of organisms resistant to amikacin, enrofloxacin, chloramphenicol, potentiated sulfonamides, and amoxicillin-clavulanic acid were low. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that IV catheters may be colonized with bacteria in 22% of young dogs suspected to have parvovirus infection.