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author:("maxime, M G")
1.  Tyzzer's Disease in a Puppy 
PMCID: PMC1790496  PMID: 17422373
2.  The kinetics of mononuclear phagocytes in normal calves given Corynebacterium parvum. 
Two groups of calves, three in each group, were used to determine the kinetics of mononuclear phagocytes in normal calves and in calves given Corynebacterium parvum intravenously, using tritiated thymidine as an in vivo deoxyribonucleic acid label. In normal calves, the mean production time of labelled monocytes in the bone marrow was 36.4 +/- 2.04 hours. The turnover rate of labelled monocytes from the bone marrow into the peripheral blood was 5.4 +/- 0.3% per hour and the disappearance rate of labelled monocytes from the circulation was 0.9 +/- 0.3%. The half lives of labelled blood monocytes were 22.5 hours for cells with 16-30 grains and 19.5 hours for cells with 31-50 grains. Alveolar macrophages were derived from peripheral blood monocytes. In calves given C. parvum, the production time, turnover rate and half lives of labelled monocytes did not differ significantly (p greater than 0.05) from the values in normal calves.
PMCID: PMC1320268  PMID: 7093810
3.  Morphology and cytochemistry of bovine bone marrow mononuclear phagocytes. 
Bone marrow samples were collected from five normal calves and mononuclear cells were separated using Ficoll-Hypaque. Mononuclear cells were cultured on coverslips in Leighton tubes for six hours. The adherent cells were differentiated using Wright's and nonspecific esterase stains. Monoblasts, promonocytes and monocytes were present in the proportion of 1:2.31:4.96.
PMCID: PMC1320266  PMID: 6178485
4.  The pulmonary clearance of Pasteurella haemolytica in calves given Corynebacterium parvum and infected with parainfluenza-3 virus. 
Four control calves were aerosolized with parainfluenza-3 and one week later with Pasteurella haemolytica. Three calves were given Corynebacterium parvum at a dose of 15 mg/m2 body surface area, infected with parainfluenza-3 virus one week later, and aerosolized with P. haemolytica two weeks after C. parvum injection. All calves were killed four hours after P. haemolytica exposure and the bacterial retention in the lung was determined. Parainfluenza-3 viral infection did not exert any suppressive effect on pulmonary clearance of P. haemolytica in six out of seven calves used. However, the bacterial colony counts in the lungs of control calves were higher (P less than 0.05) than those in calves given C. parvum. Hence, C. parvum appeared to enhance bacterial clearance. Despite the marked influx of neutrophils into the lungs after the bacterial inoculation, the neutrophil:macrophage ratio in lavage samples was less in calves given C. parvum than in the control calves. The alveolar macrophages in C. parvum treated calves were generally larger but did not differ significantly (P less than 0.05) from those in the controls. There was no significant (P less than 0.05) correlation between the percentages of alveolar macrophages and the bacterial clearance. In calves given C. parvum, bacterial clearance was enhanced in those calves which had larger macrophages.
PMCID: PMC1320202  PMID: 6280824
7.  Bovine granulocyte/macrophage and erythroid colony culture: characteristics of the colonies and the assay systems. 
Bovine bone marrow granulocyte/macrophage colonies were cultured in vitro in methyl cellulose and in plasma clots using bovine endotoxin-stimulated serum as a source of colony stimulating activity. The endotoxin-stimulated serum was four times as potent as the control serum in the methyl cellulose cultures. No significant increase in the number of colony forming units was observed when bovine marrow cells were maintained in suspension cultures for various periods prior to plating in methyl cellulose. The percentage of glass/plastic adherent cells in bovine marrow cells was observed to be 43% +/- 12 (SD). Benzidine positive erythroid colonies appeared in plasma clot cultures on day 4 and disappeared by day 9. No second population of erythroid colonies appeared either as a function of time or as a function of erythropoietin concentration. The optimum erythropoietin concentration for bovine erythroid cultures was found to be 1.0 unit/mL. A significant difference was observed between animals in their marrow capacity to produce erythroid colonies in culture but no significant difference was observed within individual animals over a period of three months.
PMCID: PMC1320020  PMID: 317645
8.  Studies with Radioactive Endotoxin III. Localization of 3H-Labelled Endotoxin in the Formed Elements of the Blood and Detection of Endotoxin in Calf Blood with the Limulus Amebocyte Lysate 
3H-labelled Pseudomonas endotoxin was incubated in vitro with blood from nontolerant and endotoxin tolerant calves. Formed elements were separated from serial samples of the incubated mixtures.
The labelled endotoxin became associated with neutrophils, monocytes, lymphocytes, platelets and erythrocytes. Association of 3H-endotoxin with formed elements of the blood occurred during the first five minutes of incubation and did not significantly change over the course of a three hour incubation period. Tolerance did not result in increased uptake of 3H-endotoxin by formed elements of the blood. Tolerance of calves to endotoxin is apparently not due to increased uptake of endotoxin by formed elements of the blood.
The Limulus amebocyte lysate assay was unreliable for the detection of endotoxin which was present in calf blood in vitro and requires further modification.
PMCID: PMC1319838  PMID: 4279756
9.  Studies with Radioactive Endotoxin II. Clearance of 3H-Labelled Endotoxin from the Blood of Calves 
The clearance of 3H-labelled Pseudomonas endotoxin from the blood was studied in a nontolerant and in an endotoxin tolerant state. Calves were rendered tolerant to the toxic effects of the endotoxin by four daily intravenous injections of endotoxin at the dose rate of 5 µg/kg body weight.
Clearance of 3H-endotoxin from the blood of nontolerant calves occurred more slowly than did clearance of 51Cr-endotoxin and was not significantly (P<0.05) affected by the development of tolerance. The lungs and liver were the major organs involved in the clearance of 3H-endotoxin from the blood of calves. Leukocytes and erythrocytes, but not platelets, were shown to participate in endotoxin clearance in calves. 3H2O, the control substance used in calves, was not concentrated within any particular organ but rapidly equilibrated with total body water and was slowly excreted.
PMCID: PMC1319837  PMID: 4279755
10.  Studies with Radioactive Endotoxin I. Clearance of 51Cr-Labelled Endotoxin from the Blood of Calves 
The clearance of 51Cr-labelled Pseudomonas endotoxin from the blood was studied in calves in a nontolerant and in an endotoxin-tolerant state. Calves were rendered tolerant to the toxic effects of the endotoxin by four daily intravenous injections of endotoxin at the dose rate of 5 µg/kg body weight.
Clearance of a small amount of 51Cr-endotoxin from the blood of nontolerant calves was almost complete within three minutes of injection and was not significantly faster in tolerant calves. The lungs and liver were the major organs involved in clearance of endotoxin from the blood. The 51Cr label was slowly excreted by the kidneys. Neither platelets nor leukocytes were demonstrated to participate in endotoxin clearance in calves. 51CrCl3 was injected into control calves. Relative to the distribution and loss of labelled endotoxin, the 51CrCl3 was cleared slowly from the blood, was distributed uniformly throughout the body and was excreted rapidly.
PMCID: PMC1319836  PMID: 4279754
11.  Atrial septal defect of the persistent ostium primum type with hypoplastic right ventricle in a Welsh pony foal. 
Valvular competency of the foramen ovale (patent foramen ovale) is regarded as a common finding in the neonatal foal and usually occurs in isolation. True atrial septal defects appear to be uncommon and are usually associated with other congenital cardiac lesions. The present report describes a case of atrial septal defect type 1 (persistent ostium primum) complicated by hypoplastic right ventricle, and tricuspid dysplasia, in a Welsh Mountain pony foal, and discusses the embryogenesis of the abnormality. A critical review of the literature suggests that atrial septal defects may occur more frequently than they are reported, and that on occasion they may be described erroneously as patent foramen ovale. The clinical significance of uncomplicated discontinuity of the atrial septum is slight, depending upon the size and location of the defect. Complicated atrial septal defects vary in clinical significance according to the nature of the associated defects.
PMCID: PMC1236206  PMID: 4075243
12.  Bovine Respiratory Syncytial Virus Infection in an Ontario Cattle Herd 
Bovine respiratory syncytial virus was recovered from the lung of a six month old calf that died during an outbreak of respiratory disease in a cattle herd in Ontario. Lung tissue removed from the calf at necropsy, performed within two hours of death, was frozen at -70°C prior to virus isolation attempts. Syncytia and intracytoplasmic inclusions were demonstrated both in histological sections of the calf's lung and in stained cell culture preparations infected with the bovine respiratory syncytial virus isolate. Direct fluorescent antibody and virus neutralization tests serologically confirmed the identity of the isolate.
PMCID: PMC1680075  PMID: 17422509
respiratory syncytial virus; virus cultivation; respiratory tract disease; bovine
13.  Fatal mastitis of dairy cows: a retrospective study. 
The necropsy records of dairy cows with mastitis were reviewed from the provincial veterinary laboratory in Guelph (44 cases of mastitis in nine years) and from the Ontario Veterinary College (168 cases in 14 years). Mastitis was considered to be the primary cause of death in 167 of 212 cows (79%). Of these 167 cases of mastitis, Escherichia coli was involved in 107 (64%), Klebsiella sp. in 12 (7%) and Staphylococcus aureus in 11 (7%). Bacteriology was not reported in 22 cases. Coliform mastitis, the most commonly identified type of fatal mastitis, was characterized histologically by the presence of infarcted areas in affected glands and by the lack of demonstrable bacteria, and was thus easily identified from fatal mastitis caused by S. aureus.
PMCID: PMC1236023  PMID: 6722641
14.  Exposure of calves to aerosols of parainfluenza-3 virus and Pasteurella haemolytica. 
The present study was undertaken to investigate whether sequential exposure to aerosols of parainfluenza-3 virus followed by Pasteurella haemolytica, or P. haemolytica followed by parainfluenza-3 virus, could lead to the production of pulmonary lesions in conventionally-raised calves. Twenty male calves with low serum antibody titres to both organisms were placed in five equal groups. Synergism of parainfluenza-3 virus and P. haemolytica was not demonstrated in any of the sequentially infected groups and pulmonary lesions were mild in all challenged calves. Clinical signs of disease were not present after exposure to parainfluenza-3 virus although the virus was repeatedly isolated from nasal secretions of all inoculated calves. Exposure to P. haemolytica produced a transient response which consisted of increased rectal temperatures and respiratory rates, with a mild neutrophilic leukocytosis and a mild left shift present six hours postinoculation and returning to normal within 24 hours. Results from this study suggest, although do not confirm, that reduced pulmonary clearance of inhaled P. haemolytica in parainfluenza-3 virus infected calves does not necessarily lead to production of severe pulmonary lesions and that previous exposure to aerosols of P. haemolytica may not enhance secondary parainfluenza-3 virus infection.
PMCID: PMC1235969  PMID: 6320999
15.  A Retrospective Study of Heart Disease in Doberman Pinscher Dogs 
The Canadian Veterinary Journal  1983;24(7):205-210.
The prevalence of gross and/or histological cardiac lesions was found to be much greater in Doberman pinscher dogs (16/26 or 62%) than in non-Doberman dogs (124/417 or 30%). At least some of the affected Dobermans were unrelated. Middle aged (mean age 4.7 yr) Dobermans of both sexes (11 M:5F) were affected. Four of the Dobermans with heart lesions had congestive cardiomyopathy; three of these four had congestive heart failure and the other one died suddenly. Prominent gross lesions were ventricular dilation and atrioventricular valvular endocardiosis. Histological lesions noted were prominent myocardial fibrosis, myofiber degeneration with fatty replacement, myofiber vacuolation and arterial intimal cushion formation. A spectrum of myocardial disease exists in Dobermans and clinically overt congestive cardiomyopathy represents one end of this spectrum.
PMCID: PMC1790348  PMID: 17422276
16.  The pulmonary clearance of Pasteurella haemolytica in calves infected with bovine virus diarrhea or Mycoplasma bovis. 
Based on current literature which commonly associates bovine virus diarrhea virus and Mycoplasma bovis with "pneumonic pasteurellosis," an investigation was conducted into the effect of these two pathogens on the capacity of bovine lung to clear inhaled Pasteurella haemolytica. There was no significant effect (p less than 0.05) of either bovine virus diarrhea virus or M. bovis on the mean clearance rate of P. haemolytica, nor did the time interval of three, five or seven days between the first inoculation and exposure to P. haemolytica and adversely affect the lung clearance rates. However, it was found that the left lungs and a higher bacterial retention (p less than 0.05) than the right lungs.
PMCID: PMC1320328  PMID: 7127194
17.  A Mouse Model for Estimation of Pasteurella haemolytica Deposition in Calf Lungs Following Aerosol Exposure 
A method used to calculate the number of Pasteurella haemolytica reaching the lungs of calves during an aerosol exposure is described. This method is based on a linear relationship of bacterial deposition in lungs of mice and calves when exposed to the same bacterial aerosol.
PMCID: PMC1320330  PMID: 7127195
18.  Biological effects of sonicated suspension and phenol-water extract of Mycoplasma mycoides subspecies mycoides in goats. 
Strain Y3343 isolated from a goat with septicemia and polyarthritis was studied. The strain was virulent and induced septicemia, polyarthritis and coagulopathy in two goats. Limulus amebocyte lysate active material was present in plasma, but not in higher titre in inoculated goats. Sonicated mycoplasma material induced a dramatic somatic cell response in the mammary gland of cows and goats and marked clotting of the cows' milk, but it did not clot limulus amebocyte lysate or kill chick embryos. Phenol-water extract clotted limulus amebocyte lysate and induced somatic cell response in cows but not in goats. The phenol-water extract did not kill chick embryos, was not pyrogenic in rabbits or goats, and did not induce generalized Shwartzman reaction or change the leukocyte kinetics in rabbits. It therfore appears that the virulence mechanisms of strain Y3343 can not be explained on the basis of factors with strong endotoxin activity.
PMCID: PMC1320278  PMID: 7046890
19.  Bovine erythrocytic, granulocytic and macrophage colony formation in culture. A preliminary report. 
Bovine erythrocytic colonies containing up to 300 cells each were produced by using a plasma clot technique with five percent CO2 at 37 degrees C. with high humidity and 2.5 units of sheep step III erythropoietin per milliliter. Erythropoietin was essential for colony formation. The number of colonies ranged from 24 to 823 per 10(5) nucleated marrow cells plated, in different animals. Some of the erythroid colonies were mixed with granulocytes. Granulocyte/macrophage colonies were produced in methyl cellulose cultures. Colonies contained up to 1000 cells and the number of colonies ranged from 13 to 981 per 10(5) nucleated marrow cells plated, from different animals. Glass adherent cells appeared to produce colony stimulating activity in culture. In both culture systems, there was a direct linear relationship between the number of nucleated marrow cells plated and the number of colonies produced.
PMCID: PMC1277645  PMID: 688074
20.  Evaluation of techniques for counting bovine platelets. 
Visual and electronic techniques for counting bovine platelets were investigated. The reference method used was hemacytometer counting of platelets in whole blood diluted with 0.85% NaCl solution. A whole blood platelet-rich plasma technique was imprecise and inaccurate. Isopycnic centrifugation of blood diluted in 8.01% NaCl solution (same density as platelets) was a precise technique, but the whole blood platelet count was underestimated. The most precise and accurate technique investigated was unit gravity sedimentation of a 1:100 dilution of blood with 10 ml of Isoton followed by electronic counting of platelets in the supernatant. This technique correlated very well with visual counting of bovine platelets (N = 77, y = 55 + 0.80x, r = 0.89, P less than 0.01).
PMCID: PMC1277741  PMID: 922558

Results 1-22 (22)