Prevalence of the 14/20 centric fusion chromosomal aberration in US Simmental cattle.

Cytogenetic evaluation was made on 353 Simmental cattle (166 male, 187 female) from 113 herds in 26 states. One hundred thirty-eight (39%) were found to be heterozygous-positive for the 14/20 centric fusion chromosomal translocation, including 41 (25%) males and 97 (52%) females. One submitted heparinized blood sample from a Simbrah bull was found to be positive for 14/20 and 1/29 centric fusions. Sampling, which was based on requests, was highly selective. Thus, the 39% prevalence found was not representative of 14/20 centric fusion in the national Simmental breed. On the basis of our findings, cytogenetic evaluation of breeding stock was consistent with modern management practice.     

Comparison of the ability of feline calicivirus (FCV) vaccines to neutralise a panel of current UK FCV isolates

Feline calicivirus (FCV) comprises a large number of strains which are related antigenically to varying degrees. The antigenic variability creates problems for choosing antigens to include in vaccines. Historically, these have been selected for use based on their cross-reactivity with a high proportion of field strains. However, it is important to determine the current level of cross-reactivity of vaccines and whether or not this may be decreasing owing to widespread vaccine use. In this in vitro study, we have compared the ability of antisera to two vaccine viruses (FCV strain F9 and FCV strain 255) to neutralise a panel of 40 recent UK field isolates. These 40 isolates were obtained by randomised, cross-sectional sampling of veterinary practices in different geographical regions of the UK so as to ensure they were representative of viruses circulating in the veterinary-visiting population of cats in the UK. Virus neutralisation assays showed that both vaccine strains are still broadly cross-reactive, with F9 antiserum neutralising 87.5% and 255 antiserum 75% of isolates tested with antiserum dilutions of 1 in 2 or greater. However, when antibody units were used, in order to take account of differences in homologous titres between antisera, fewer isolates were neutralised, with F9 antiserum showing a slightly higher proportion of isolates neutralised than 255. Multivariable analysis of the sample population of 1206 cats from which the 40 isolates were derived found that vaccinated cats were at a decreased risk of being positive for FCV, whereas cats from households with more than one cat, and cats with mouth ulcers were at increased risk. In addition as cats became older their risk of shedding FCV decreased.     

Modeling temporal progress of plant diseases

A model for describing temporal progress of plant diseases is presented. The model (termed a ‘mixed’ model) coincides in two special cases with the logistic and the monomolecular models introduced by Vanderplank. The mixed model is implemented using some data available on the spread of zucchini yellow mosaic virus (ZYMV) from a field experiment in Israel.     

Physicochemical properties of agrochemicals: Their effects on foliar penetration

Uptake and translocation of 26 chemicals (herbicides, fungicides, growth regulators, insecticides and model compounds), formulated with and without ‘Ethylan TU’ (NP8) surfactant, have been determined 24, 48 and 72 h after spraying onto leaves of maize, rape, strawberry and sugar beet. Eight of the chemicals may be classified as polar (log partition coefficient (P) < 0) and 18 as lipophilic (log P 0·8-4·6). Chemicals penetrated more readily into waxy leaves of rape and strawberry than into less-waxy sugar beet, whilst lowest rates were observed for maize. Rates of uptake varied from exceedingly low (< 2% 72 h after application) for uracil, maleic hydrazide, isoproturon and methyl phenylurea applied to maize, to rapid (>98% within 24 h of application) for acephate and triadimefon applied to strawberry leaves. The effects of NP8 on rates of chemical uptake were classified into 4 types, viz:-

• (i) low rates, with limited enhancement by NP8;
• (ii) high rates unaffected by NP8;
• (iiii) marked enhancement by NP8 within 24 h; and
• (iv) continuous enhancement by NP8 over 0-72 h.

Translocation into the tissues immediately adjacent to the target site was greater for waxy than less-waxy plants, enhancement by NP8 was attributed to its effects on penetration rather than to surfactant interactions at the sub-cuticular level. Logarithms of physicochemical properties (partition coefficient, water solubility S, molecular weight MW), together with deposit area and melting point (m.p.) values were used to investigate relationships with uptake and translocation. In most cases the variability could not be described adequately in a simple linear form. Regressions using the entire group of 26 chemicals also showed poor correlations between uptake patterns and individual variables. Polynomials in log S, log P, log MW and m.p. were used to test for complex relationships. A quadratic polynomial in log P, log S and m.p. accounted for slightly more (77%) of the variability between the means for total uptake than a cubic polynomial in log P and log S (75%). Although both regressions were significant, the ‘lack of fit’ indicated that other factors need to be included to account fully for the variability in rates of uptake and translocation.     

Lesions of perirenal hemorrhage syndrome in growing turkeys

Turkeys from six market flocks were examined at 8 to 19 weeks of age to assess morphologic lesions of perirenal hemorrhage syndrome (PHS). PHS was diagnosed in 165 of 715 turkeys necropsied, and 82 turkeys served as age- and weight-matched controls. The most consistent gross findings were rounded pectoral muscles of normal color, ingesta-filled crops and gizzards, variable retroperitoneal perirenal hemorrhage, a swollen dark red and light purple spleen, congested intestinal blood vessels, and pulmonary edema and/or hemorrhage. The main histologic lesions of PHS were perivascular edema in lungs and kidneys, vascular congestion of various organs, renal perivenous hemorrhage, and proliferative arterial and arteriolar lesions in the spleen and kidneys that were more severe than those in controls. Heart weights, including mean relative weights of the right and combined left ventricles and interventricular septa, were significantly greater in turkeys that died with PHS than in controls. Scores for tibial dyschondroplasia and "breast blisters" were more severe in turkeys that died with PHS than in controls. The cardiovascular system appeared to be the PHS target system.     

Disseminated intravascular coagulation in a horse with postpartum ulcerative colitis and laminitis

Hemostatic studies were conducted on a five year old Belgian mare presented two days postpartum with colic and laminitis that was unresponsive to treatment.

The mare was moderately thrombocytopenic with plasma fibrinogen levels more than twice that of a normal control horse. Platelet function as evaluated by aggregometry indicated that the circulating platelets were markedly hyporesponsive. Activated partial thromboplastin times and prothrombin times were prolonged. Para-coagulation tests (protamine sulfate and ethanol gelation) were strongly positive and fibrin degradation products were significantly elevated in the serum.

The laboratory data suggested that the clinical bleeding was the result of the development of disseminated intravascular coagulation. The data were compatible with intravascular activation of the clotting mechanism, consumption of hemostatic factors, inhibition of platelet function and enhanced stimulation of the fibrinolytic mechanism.

This report illustrates the complexity of the hemostatic abnormalities associated with pathological overactivation of the hemostatic mechanism. Factors such as tissue thromboplastins and/or endotoxins can stimulate disseminated intravascular coagulation, particularly during pregnancy or in the early postpartum period when a physiological “hypercoagulable” state already exists.