Clinicopathological investigation of primary, uncomplicated maedi-visna virus infection.

Maedi-visna virus infection in a flock of sheep in Scotland was associated with respiratory disease, neurological disease, mastitis and lameness. The major clinical signs were dyspnoea (particularly on exercise), progressive fore- and hindlimb ataxia and balance defects, mammary induration and multilimb lameness, occasionally with enlarged carpal joints. Pathological examinations revealed lesions in the lungs, central nervous system, mammary glands and joints which were consistent with those induced by maedi-visna virus. The was no clinical or pathological evidence of concurrent sheep pulmonary adenomatosis, and pulmonary bacterial infections, when they occurred, were superimposed on the lesions due to maedi-visna virus.     

Attempt to control parturition in the sow using an oral progestogen

Analogues of prostaglandin F2 alpha are widely used in the United Kingdom to induce parturition in sows. A disadvantage is that sows are induced to farrow in advance of expected delivery dates. An alternative might be to maintain gestation by the application of a progestogen. Farrowing might then be initiated on the withdrawal of the progestogen. The use of an orally active progestogen (allyl-trenbolone) in an attempt to control the time of parturition in sows is described. In experiment 1, 20 large white cross landrace sows were allocated at random to one of two treatments. Treated sows were fed 16 mg/day of allyl-trenbolone from day 111 of gestation to day 118 of gestation. The farrowing performance of these sows was compared with that of control sows which farrowed naturally. Treated sows farrowed significantly (P less than 0.01) later than the control sows (118.2 and 116.1 days respectively). For treated sows the interval from progestogen withdrawal to farrowing was 29.6 +/- 4.8 hours. The number of stillbirths for treated and control sows respectively was 2.1 and 0.4 per litter. Treatment had no effect either on the birth weight of piglets or on their weaning weight at six weeks old. There was a tendency for more treated sows to show subsequent reproductive malfunction. In a second experiment, under commercial conditions, 81 sows and 12 gilts were allocated to one of four treatments. Treatment A animals were untreated controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nanocatalysis by the tip of a scanning tunneling microscope operating inside a reactor cell

The platinum-rhodium tip of a scanning tunneling microscope that operates inside of an atmospheric-pressure chemical reactor cell has been used to locally rehydrogenate carbonaceous fragments deposited on the (111) surface of platinum. The carbon fragments were produced by partial dehydrogenation of propylene. The reactant gas environment inside the cell consisted of pure H(2) or a 1:9 mixture of CH(3)CHCH(2) and H(2) at 300 kelvin. The platinum-rhodium tip acted as a catalyst after activation by short voltage pulses. In this active state, the clusters in the area scanned by the tip were reacted away with very high spatial resolution.     

Insecticidal,repellent and fungicidal properties of novel trifluoromethylphenyl amides

Twenty trifluoromethylphenyl amides were synthesized and evaluated as fungicides and as mosquito toxicants and repellents. Against Aedes aegypti larvae, N-(2,6-dichloro-4-(trifluoromethyl)phenyl)-3,5-dinitrobenzamide (1e) was the most toxic compound (24 h LC₅₀ 1940 nM), while against adults N-(2,6-dichloro-4-(trifluoromethyl)phenyl)-2,2,2-trifluoroacetamide (1c) was most active (24 h LD₅₀ 19.182 nM, 0.5 μL/insect). However, the 24 h LC₅₀ and LD₅₀ values of fipronil against Ae. aegypti larvae and adults were significantly lower: 13.55 nM and 0.787 × 10⁻⁴ nM, respectively. Compound 1c was also active against Drosophila melanogaster adults with 24 h LC₅₀ values of 5.6 and 4.9 μg/cm² for the Oregon-R and 1675 strains, respectively. Fipronil had LC₅₀ values of 0.004 and 0.017 μg/cm² against the two strains of D. melanogaster, respectively. In repellency bioassays against female Ae. aegypti, 2,2,2-trifluoro-N-(2-(trifluoromethyl)phenyl)acetamide (4c) had the highest repellent potency with a minimum effective dosage (MED) of 0.039 μmol/cm² compared to DEET (MED of 0.091 μmol/cm²). Compound N-(2-(trifluoromethyl)phenyl)hexanamide (4a) had an MED of 0.091 μmol/cm² which was comparable to DEET. Compound 4c was the most potent fungicide against Phomopsis obscurans. Several trends were discerned between the structural configuration of these molecules and the effect of structural changes on toxicity and repellency. Para- or meta- trifluoromethylphenyl amides with an aromatic ring attached to the carbonyl carbon showed higher toxicity against Ae. aegypti larvae, than ortho- trifluoromethylphenyl amides. Ortho- trifluoromethylphenyl amides with trifluoromethyl or alkyl group attached to the carbonyl carbon produced higher repellent activity against female Ae. aegypti and Anopheles albimanus than meta- or para- trifluoromethylphenyl amides. The presence of 2,6-dichloro- substitution on the phenyl ring of the amide had an influence on larvicidal and repellent activity of para- trifluoromethylphenyl amides.