Deposition and clearance of monodisperse aerosols in the calf lung: effects of particle size and a mucolytic agent (bromhexine)

Mucociliary clearance and retention of monodisperse aerosols of radiolabelled polystyrene particles of both 3.3 microns and 5 microns diameter were investigated in four healthy calves and two sick calves. The effect of the mucolytic agent bromhexine was also assessed at two dosage levels. There were significant differences (P less than 0.05) in clearance rate constant between calves, but similar patterns of clearance for each calf. These characteristics of mechanical lung clearance did not vary over a two month period. Values of clearance rate constant and percentage retention varied significantly (P less than 0.001) between the two different particle sizes, 5 microns particles giving faster clearance and lower retention of particles than 3.3 microns particles. Bromhexine at the recommended dose of 1.6 mg/kg 0.75 caused a significant (P less than 0.05) increase in clearance rate in both healthy and sick calves, but affected percentage retention only in sick calves. This study illustrates the variation in mucociliary clearance rates shown by individuals and also underlines the importance of particle size in aerosols used for studies of pulmonary deposition and clearance. The work also indicates that bromhexine may be of use in the therapy of respiratory disease in calves.     

Mucociliary clearance from the calf lung.

Mucociliary clearance rate constants for ten calves were obtained using Technetium 99m-sulphur colloid complex. The mean rate constant measured at the lung for all calves was 0.012 (+/- 0.009) min-1 (half-life 58 minutes). The clearance rate constants obtained from measurements made at the larynx were higher (0.02 +/- 0.007 min-1), although not significantly higher, than those determined from measurements taken at the lung. The constants can be used to predict the particle burden on the lungs of calves kept under husbandry systems of varying air hygiene.     

The incidence of Mycoplasma dispar, Ureaplasma and conventional Mycoplasma in the pneumonic calf lung.

This report describes the incidence of Mycoplasma dispar, ureaplasma and conventional (large colony) mycoplasma isolated from the pneumonic lungs of groups of young calves and the identification to species level of mycoplasmas in mixed populations with the aid of the indirect fluorescent antibody test. Pneumonic lung tissue yielded one or more mycoplasma species from 88% of the 153 calves cultured. The mycoplasmas identified and percent of the calves with lungs positive for each species were: M. dispar (56%), ureaplasma (44%), Mycoplasma bovis (37%), Mycoplasma arginini (33%) and Mycoplasma bovirhinis (23%). Conventional mycoplasmas isolated from two calves (1%) could not be identified using the antisera available.     

国内首次从患肺炎的犊牛肺脏中分离到牛支原体

牛支原体(Mycoplasma boris)是引起犊牛肺炎、关节炎和成牛乳房炎的主要病原之一.本研究利用选择性培养基从2份患肺炎的犊牛肺脏病料中得到2株支原体,分别命名为Hubei-1和Hubei-2,并在固体培养基进行了3次克隆纯化.通过生化实验、特异性PCR鉴定和序列比较证明为牛支原体.其16S rRNA 核酸序列与牛支原体国际标准株PG45同源性为99.3%.以该培养物作为包被抗原的ELISA 检测方法对13份发病犊牛血清进行了检测,其中11份血清抗体OD值为阴性血清对照值的2倍以上.该结果首次证实,国内部分地区存在牛支原体的流行.     

The airborne survival of Pasteurella haemolytica and its deposition in and clearance from the mouse lung

Pasteurella haemolytica A1 was aerosolised by a Collison nebuliser in a Henderson apparatus and its survival in air was measured. The organism was fragile in aerosol and survived best at high humidity and warm temperature. Mice were exposed to the aerosol and clearance from the lung measured. Deposition in the mouse lung showed a good linear correlation with bacterial concentration in the spray suspension fluid. Clearance from the lung was rapid over 24 h although some bacteria could be detected 2 and 4 days after exposure. Mice which received a second exposure 2 weeks later exhibited accelerated clearance from the lung whereby no bacteria could be detected after 12 h. This was associated with serum IgG antibody production, and local and splenic lymphocyte responses to bacterial antigen in vitro.     

Studies on the cytopathology of bovine adenoviruses in calf testis and calf kidney cell cultures

The sequential development of intranuclear inclusions in calf kidney and calf testis cells infected with nine bovine adenovirus (BAV) serotypes is described. Haematoxylin and Eosin (H & E), immunofluorescent and electron microscope (EM) studies indicated two distinct subgroups of viruses. Serotypes 1, 2, 3, 7 and 9 comprised subgroup-1, while types 4, 5, 6 and 8 comprised subgroup-2. Differences were noted in the early stages of infection. With subgroup-1 viruses, irregular patches of eosinophilic material were first to appear, followed by small refractile inclusions and basophilic inclusions. In EM studies, the eosinophilic material was thought to correspond to the irregular type II inclusions, and the refractile bodies to type I inclusions. Eventually a basophilic inclusion, consisting of aggregated virus-associated inclusions and virus particles, was formed in the centre of the nucleus.With subgroup-2, the refractile inclusions were more prominent, larger, and were the first to appear. These were thought to correspond to type I inclusions, which were larger and denser than with subgroup-1. Circular basophilic bodies developing later were similar in size and distribution to type II inclusions, which with subgroup-2 viruses were seen in prominent circular or lobulated aggregates.Several other types of inclusion including tubular structures and paracrystals, which have thus far not been reported in BAV infected cells, are described.     

Atlanto-occipital fusion and ataxia in the calf

Atlanto-occipital fusion is a rare bony anomaly due to the failure of the developing arches of the first cervical vertebra to separate from the occiput. It may be associated with compressive myelopathy and must therefore be considered in the differential diagnosis of ataxia in the young animal. This report reviews the embryological development of the region and reports the findings in two cases of fusion in the calf.     

Chloramphenicol and the neonatal calf

Pharmacokinetic values and possible toxic effects of chloramphenicol on bone marrow and hematologic and serum chemical values were determined in newborn calves given the drug (IV) once a week or in repeated doses, 12 hours between doses. The rates of elimination for chloramphenicol and antipyrine also were compared. Chloramphenicol also was administered to older calves by IM and subcutaneous routes, with an apparent bioavailability of 50% to 60%. The elimination half-lives for both chloramphenicol and antipyrine were markedly increased in the newborn calf for at least the first 3 to 4 weeks of life. Despite the high and prolonged serum chloramphenicol concentrations in these calves, there was little or no indication of toxic effects. Bone marrow aspirates did not reveal any signs of intoxication such as cytoplasmic or nuclear vacuolation. Marrow cellularity was not recognizably different from the control group.     

Microbiologic studies of the lung clearance of rats after aerogenous long term exposure to ammonia

The effects of aerogenic long-time exposure of 1,990 female Wistar rats to 30, 50, 100 and 150 nl/l of NH3 for 3, 14, 28 and 42 days on clearance of inhaled bacteria (Staphylococcus aureus, SG 511 strain) were studied together with effects on the clinical condition and behaviour of these test animals. For concentrations below 100 nl/l, action upon pulmonary clearance was found to depend above all on the length of exposure, whereas effects of 150 nl/l proved to depend more strongly on concentration. All concentrations tested tended to act on pulmonary clearance in the form of increased numbers of bacteria which remained in the lungs of the experimental animals. Clinical symptoms attributable to NH3 action were not recordable.     

Hemodynamic effects of xylazine in the calf

The hemodynamic effects of sedative level doses of xylazine in five chronically instrumented calves were studied. These effects included immediate and prolonged reductions in heart rate, cardiac output, arterial blood pressure, and left ventricular dp/dt max. Stroke volume showed an initial decrease in value with a return in 15 minutes to base-line values. Total peripheral resistance, end-diastolic left ventricular pressure, end-diastolic left ventricular volume, and left ventricular residual fraction were increased after drug administration. The results indicate that a depressed myocardium results from xylazine administration. With one exception (the absence of a hypertensive response), these effects largely parallel, both quantitatively and qualitatively, those seen with this drug in other species. Sedation by xylazine is produced in cattle at doses which are small compared to those which is required for sedation in other species. These same small doses in cattle also cause hemodynamic changes.     

Physiopathological studies of thyroid function in the calf. 1. Diagnosis of thyroid function in the calf

Clinico-chemical and radiometric methods, common in routine diagnosis in human medicine for in-vitro assessment of thyroid function, were tested for their applicability to calf. The assessment of protein-fixed iodine and of iodine extractable from stock, the thyroxine test, the tri-iodothyronine test, the tri-iodothyronine radio-immuno assay, and the effective thyroxine ratio test, basically, were applicable to diagnosis of thyroid function in calf. The thyrotrophin releasing hormone test, in conjunction with efforts to determine peripheral thyroid gland hormone concentration (in particular tri-iodothyronine), was also applicable to calf, although thyroid stimulation hormone with radio-immuno assay, another procedure in human medicine (specificity of thyroid stimulation hormone antibody), proved unsuitable for the determination of bovine thyroid stimulation hormone.