Rheumatoid factor-like IgM in Plasmodium berghei (Apicomplexa: Haemosporida) infections of BALB/c mice

Groups of female BALB/c mice infected by intravenous injection with 50 erythrocytes containing Plasmodium berghei Vincke et Lips, 1948 were sacrificed on days 3 through 12 after infection. Rheumatoid factor-like IgM (RF-IgM) and parasite-specific IgG levels were determined by enzyme-linked immunosorbent assay in serum specimens and in culture medium removed from spleen cell cultures established at sacrifice. All four mouse IgG subisotypes were recognized by RF-IgM molecules induced by Plasmodium berghei infection, and in this regard, the parasite-induced RF-IgM response resembled that induced by lipopolysaccharide polyclonal activation. Plasmodium berghei infection resulted in a biphasic RF-IgM response, with infected animals demonstrating significantly increased levels of RF-IgM early in the infection and significantly decreased levels late in the infection, compared to uninfected control mice. The decreased levels of RF-IgM observed late in infection correlated with increasing parasitaemia levels, and were primarily due to a decrease in RF-IgM specific for mouse IgG2a. Late infection levels of RF-IgM specific for IgGI, IgG2b, and IgG3 were not significantly different from those of control animals.     

Diversity of Epidemic Populations of Gibberella zeae from Small Quadrats in Kansas and North Dakota

ABSTRACT Gibberella zeae (anamorph Fusarium graminearum) causes Fusarium head blight (FHB) of wheat and barley and has been responsible for several billion dollars of losses in the United States since the early 1990s. We isolated G. zeae from the top, middle, and bottom positions of wheat spikes collected from 0.25-m(2) quadrats during severe FHB epidemics in a single Kansas (KS) field (1993) and in a single North Dakota (ND) field (1994). Three amplified fragment length polymorphism (AFLP) primer pairs were used to resolve 94 polymorphic loci from 253 isolates. Members of a subset of 26 isolates also were tested for vegetative compatibility groups (VCGs). Both methods indicated high levels of genotypic variability and identified the same sets of isolates as probable clones. The mean number of AFLP multilocus haplotypes per head was approximately 1.8 in each population, but this value probably underestimates the true mean due to the small number of samples taken from each head. Isolates with the same AFLP haplotype often were recovered from different positions in a single head, but only rarely were such apparently clonal isolates recovered from more than one head within a quadrat, a pattern that is consistent with a genetically diverse initial inoculum and limited secondary spread. The KS and ND samples had no common AFLP haplotypes. All G. zeae isolates had high AFLP fingerprint similarity (>70%, unweighted pair group method with arithmetic means similarity) to reference isolates of G. zeae lineage 7. The genetic identity between the KS and ND populations was >99% and the estimated effective migration rate was high (Nm approximately 70). Tests for linkage disequilibrium provide little evidence for nonrandom associations between loci. Our results suggest that these populations are parts of a single, panmictic population that experiences frequent recombination. Our results also suggest that a variety of population sampling designs may be satisfactory for assessing diversity in this fungus.     

Biomolecular relationships among isolates of<Emphasis Type="Italic">Tomato Yellow Leaf Curl Tanzania Virus</Emphasis>

An investigation of the biological properties of the virus causing tomato yellow leaf curl disease in Tanzania was initiated to compare it with other known tomato yellow leaf curl viruses. Properties relating to acquisition and inoculation feeding time, persistence, mechanical inoculation, seed transmission and host range were studied. Results obtained indicate that the virus was transmitted persistently byBemisia tabaci Genn., but it was not mechanically, sap- or seed-transmissible. Minimum acquisition and inoculation feeding time was 30 min.Capsicum annuum, Datura stramonium, Nicotiana glutinosa, N. tabacum andLycopersicon esculentum were found to be hosts of the virus among the plant species tested, whereasPhaseolus vulgaris was not. It is concluded that the properties of the agent causing yellow leaf curl symptoms in tomato plants from different regions in Tanzania are similar to those ofTomato yellow leaf curl Sardinia virus species studied elsewhere. http://www.phytoparasitica.org posting Feb. 20, 2003.     

Insect chemical ecology research in the United States Department of Agriculture-Agricultural Research Service

This multi-author paper reviews current work by USDA-ARS scientists in the field of chemical ecology. Work with pheromones, the discovery and development of the codling moth kairomone, studies on insect-plant interactions and chemically mediated tritrophic plant-insect interactions have led to practical methods for control of important insect pests.     

Isolation and differentiation of bovine mammary gland progenitor cell populations

OBJECTIVE: To isolate bovine mammary gland cells with stem cell characteristics. SAMPLE POPULATION: Monolayers of bovine mammary gland cells. PROCEDURE: Mammary gland cell populations were separated by use of selected media supplements. Phenotypic characteristics were examined via light and transmission electron microscopy. Cellular expression of casein and connexin 43 was identified immunohistochemically. A scrape-loading and dye transfer assay was used to examine the mammary gland cell populations for homogenous gap junctional intercellular communication (GJIC). RESULTS: Subpopulations of mammary gland cells grown in vitro are classified on the basis of their distinct morphologic features and ability to communicate via gap junctions. Ultrastructurally, 2 morphologically distinct cell types were classified as type I and II cells. Type I cells were small light undiffertiated cells and large light undifferentiated cells that were deficient in functional gap junctions (as is characteristic of stem cells). Type II cells included large light differentiated cells and terminally differentiated cells; GJIC was functional in type II cells. Type II cells had cytoplasmic expression of connexin 43, whereas, type I cells did not. All cells expressed casein. CONCLUSIONS AND CLINICAL RELEVANCE: Subpopulations of bovine mammary gland cells with stem cell characteristics were identified. Phenotypic differences are observed among type I bovine mammary gland cells with stem cell characteristics. Gap junctional intercellular communication may be necessary for the differentiation of stem cells. Characterization of bovine mammary gland stem cells and their progeny may provide a new tool with which to study mammary gland health.     

Use of positive contrast rhinography and intranasal sinography for diagnosis of a nasofacial sinus tract in a dog

Twelve days after a dog fight, a 2-year-old sexually intact female Bulldog was evaluated because of subcutaneous emphysema of increasing severity throughout the dogs body. Thoracic radiography revealed severe pneumomediastinum from which free air had extended into the retroperitoneal space, resulting in pneumoperitoneum. Tracheoscopic examination did not reveal a discontinuity of the trachea, pharynx, or larynx. A breach between the nasal cavity and subcutaneous tissues of the nasal region was suspected. Further diagnostic investigations included positive contrast rhinography and intranasal sinography. Via an angiographic catheter inserted into the left naris, positive contrast intranasal sinography revealed a sinus tract extending between the left nasal cavity and the subcutaneous tissue of the dorsal aspect of the nasal planum. Resolution of subcutaneous emphysema, pneumomediastinum, and pneumoretroperitoneum began 1 day after surgical closure of the intranasal opening of the sinus tract. To the authors' knowledge, this radiographic technique has not been reported.     

Outcome of and complications associated with prophylactic percutaneous laser disk ablation in dogs with thoracolumbar disk disease: 277 cases (1992-2001)

OBJECTIVE: To determine outcome of and complications associated with prophylactic percutaneous laser disk ablation in dogs with thoracolumbar disk disease. DESIGN: Retrospective study. ANIMALS: 277 dogs. PROCEDURE: Medical records of dogs with a history of thoracolumbar disk disease in which the 7 intervertebral disks from T10-11 through L3-4 were ablated with a holmium-yttrium-aluminum-garnet laser inserted through percutaneously placed needles were reviewed. Complications and episodes of a recurrence of neurologic signs (eg, paresis or paralysis) were recorded. Owners were contacted by telephone for follow-up information. RESULTS: Nine of 262 (3.4%) dogs for which follow-up information was available had a recurrence of paresis or paralysis. Follow-up time ranged from 1 to 85 months (mean, 15 months); signs recurred between 3 and 52 months (mean, 15.1 months) after laser disk ablation. Acute complications occurred in 5 dogs and included mild pneumothorax in 1 dog, an abscess at a needle insertion site in 1 dog, and proprioceptive deficits in 3 dogs, 1 of which required hemilaminectomy within 1 week because of progression and severity of neurologic signs. One dog developed diskospondylitis. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that prophylactic percutaneous laser disk ablation is associated with few complications and may reduce the risk of recurrence of signs of intervertebral disk disease in dogs.     

Taurine deficiency in dogs with dilated cardiomyopathy: 12 cases (1997-2001)

OBJECTIVE: To determine signalment, history, clinical signs, blood and plasma taurine concentrations, electrocardiographic and echocardiographic findings, treatment, and outcome of dogs with low blood or plasma taurine concentrations and dilated cardiomyopathy (DCM). DESIGN: Retrospective study. ANIMALS: 12 client-owned dogs with low blood or plasma taurine concentrations and DCM. PROCEDURE: Medical records were reviewed, and clinical data were obtained. RESULTS: All 12 dogs were being fed a commercial dry diet containing lamb meal, rice, or both as primary ingredients. Cardiac function and plasma taurine concentration improved with treatment and taurine supplementation. Seven of the 12 dogs that were still alive at the time of the study were receiving no cardiac medications except taurine. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that consumption of certain commercial diets may be associated with low blood or plasma taurine concentrations and DCM in dogs. Taurine supplementation may result in prolonged survival times in these dogs, which is not typical for dogs with DCM. Samples should be submitted for measurement of blood and plasma taurine concentrations in dogs with DCM, and taurine supplementation is recommended while results of these analyses are pending.     

Prophylactic use of decoquinate for infections with Cryptosporidium parvum in experimentally challenged neonatal calves

OBJECTIVE: To evaluate the effect of daily oral administration of decoquinate to neonatal calves experimentally challenged with various numbers of Cryptosporidium parvum oocysts. DESIGN: Clinical trial. ANIMALS: 75 calves. PROCEDURE: Calves were purchased from a commercial dairy during a 5-week period. Calves were housed in individual hutches and fed milk replacer with or without decoquinate (2 mg/kg [0.9 mg/lb per day]). Calves were randomly assigned to treatment and 1 of 5 challenge groups (0, 50, 100, 1000, or 10,000 C. parvum oocysts in 60 mL of saline [0.9% NaCl] solution administered p.o. on the day after arrival). Calves were maintained in the study for as long as 28 days. Calves were clinically assessed for diarrhea and dehydration. Fecal samples were submitted for oocyst enumeration 3 times each week. RESULTS: Treatment did not affect number of days to first watery feces (diarrhea), number of days to first oocyst shedding, or duration of diarrhea or oocyst shedding. Duration of oocyst shedding was significantly associated with challenge dose of oocysts administered to calves and number of days to first oocyst shedding. Duration of diarrhea and number of days to first oocyst shedding were significantly associated with week of arrival and number of days to first watery diarrhea. CONCLUSIONS AND CLINICAL RELEVANCE: Daily treatment with decoquinate at the dosage used in this study did not affect oocyst shedding or clinical signs associated with cryptosporidiosis. However, there was an indication that if the number of oocysts calves received could be reduced, then the duration of oocyst shedding and, hence, environmental loading of C. parvum oocysts could be reduced.     

Evolution of bacterial resistance to certain antibacterial agents in horses in a veterinary hospital

Evolution of bacterial resistance to certain antibacterial agents in horses in a veterinary hospital. A total of 255 antibiograms, conducted according to the Kirby-Bauer method from bacterial isolates collected from horses at the H?pital Vétérinaire d'Enseignement at the Université de Montréal between 1996 and 1998 were compared with the results obtained about 10 years ago with corresponding bacterial species. A significant increase in the percentage of strains resistant to trimethoprim-sulfamethoxazole (TMP-SXT), penicilline, tetracycline, and to gentamicin was observed. The percentages of isolates of Actinobacillus spp. and coagulase-positive staphylococci resistant to TMP-SXT increased from 0% to 17% and from 0% to 33%, respectively, (P < 0.05). The percentage of isolates of Actinobacillus spp resistant to penicilline also increased from 33% to 73% (P < 0.05). Regular monitoring of the evolution of bacterial resistance to antibacterial agents is indispensable in a hospital structure. The adoption of "good antibiotherapy practices" is essential to guarantee a decrease in the risks of selection and dissemination of a resistant bacterial strain.