Efficacy of milbemycin oxime against fourth-stage larvae and adults of Ancylostoma tubaeforme in experimentally infected cats.

The efficacy of milbemycin oxime against fourth-stage (L4) larvae and adults of Ancylostoma tubaeforme was investigated in a trial involving 24 young domestic shorthair cats. The animals were inoculated with approximately 300 infective stage three (L3) larvae and divided into three groups. After 12 days, eight cats (group 1) were treated with medicated tablets containing 4 mg milbemycin and 10 mg praziquantel to test the efficacy against L4 larvae; eight cats in group 2 were treated with the same tablets after 33 days to test the efficacy against adult worms; and eight cats in group 3 were treated with a placebo tablet. Faecal egg counts were determined periodically in each cat and after 40 or 41 days the number of worms in each animal was determined postmortem. The egg count reduction was determined by comparing the geometric mean numbers of eggs per gram of faeces in the placebo and medicated groups, and the worm reduction by comparing the geometric mean numbers of worms. The egg count reduction was more than 99 per cent in both treated groups, while the number of worms in groups 1 and 2 were reduced by 94.7 per cent and 99.2 per cent, respectively.

Comparative speed of kill between nitenpyram, fipronil, imidacloprid, selamectin and cythioate against adult Ctenocephalides felis (Bouché) on cats and dogs.

Speed of kill and percentage kill of nitenpyram (CAPSTAR) was compared to fipronil (Frontline) spot-on), imidacloprid (Bayvantage/Advantage), selamectin (Stronghold/Revolution) and cythioate (Cyflee) against adult fleas on cats and dogs 3 and 8h post-treatment. Selamectin was used on dogs only; cythioate was used on cats only. Groups of eight cats and eight dogs (four males and four females each) were experimentally infested with 100 unfed fleas 1 day prior to treatment with the test products. One group of cats and one group of dogs served as control. Fleas were collected from four cats and four dogs in each group (two males and two females) by combing 3h after treatment, the remaining four cats or dogs were combed 8h after treatment. In cats cythioate treatment resulted in a mean efficacy of 62.4 and 97.4% at 3 and 8h post-treatment, respectively. Imidacloprid efficacy at the same times was 26.9 and 82.8%, whereas fipronil efficacy was 24.3 and 62.6% efficacy, respectively. In dogs mean efficacy 3 and 8h after treatment with selamectin was 39.7 and 74.4%; with imidacloprid efficacy was 22.2 and 95.7%, respectively and 35.9 and 46.5%, respectively after treatment with fipronil. Nitenpyram was 100% effective in cats and 99.1% effective in dogs within 3h of treatment and 100% effective in cats and dogs within 8h.

Plasma angiotensin converting enzyme activity and pharmacokinetics of benazepril and benazeprilat in cats after single and repeated oral administration of benazepril.HCl.

The plasma pharmacokinetics of benazepril and its active metabolite, benazeprilat, were determined in cats after oral administration of benazepril.HCl at dosages of 0.25, 0.5 and 1.0 mg/kg as a single dose (n = 5 per group) and after once daily application for 8 days (n = 6 per group). Pharmacodynamics were assessed by measurement of plasma angiotensin converting enzyme (ACE) activity. After single administration of benazepril.HCl, maximum benazepril concentrations were recorded at the first sample (2 h) and declined relatively rapidly with an elimination half life (t1/2) of 1.4 h. Highest benazeprilat concentrations were recorded at the first sample (2 h) in most cats and declined biphasically with half lives of each phase of 2.4 and 27.7 h. With repeated administration, plasma benazeprilat concentrations accumulated slightly with accumulation ratios (R) of 1.46, 1.36 and 1.24 for the 0.25, 0.5 and 1.0 mg/kg dosages of benazepril.HCl, respectively (median value of 1.36 for all dosages). All three dosages of benazepril.HCl caused marked inhibition of plasma ACE activity in all cats. The maximum effect (Emax, % inhibition of ACE as compared to baseline) was > or = 98% after single and 100% with repeated administration. The duration of action of benazepril.HCl was long, with > 87% (single) and > 90% (repeat) inhibition of plasma ACE persisting 24 h after dosing. Benazepril.HCl was well tolerated in all animals. Dosages of 0.25-1.0 mg/kg benazepril.HCl once daily are recommended for clinical testing in cats.

Infectious in vivo and in vitro transcripts from a full-length cDNA clone of PVY-N605, a Swiss necrotic isolate of potato virus Y.

A full-length cDNA clone of the potato virus Y (PVY) genome was obtained after cloning difficulties in Escherichia coli were overcome. These difficulties were mainly due to the expression of the CI gene from upstream prokaryotic promoter-like elements within the PVY genome. To overcome this problem, PVY cDNA was maintained in two subclones which were ligated before infection. A plasmid in which these two fragments were contained could be propagated in some E. coli strains but was unstable and yielded only low levels of plasmid DNA. Replacement of the 35S promoter by the SP6 promoter slightly increased the stability of the plasmid and its RNA transcripts were infectious when capped with m7G(5')ppp(5')G. Using two inoculation methods (mechanical or biolistic) the cDNA and its RNA transcript proved infectious on three Nicotiana species and on Solanum tuberosum.

Influence of surface and protein modification on immunoglobulin G adsorption observed by scanning force microscopy.

Scanning force microscopy has been used successfully to produce images of individual protein molecules. However, one of the problems with this approach has been the high mobility of the proteins caused by the interaction between the sample and the scanning tip. To stabilize the proteins we have modified the adsorption properties of immunoglobulin G on graphite and mica surfaces. We have used two approaches: first, we applied glow discharge treatment to the surface to increase the hydrophilicity, favoring adhesion of hydrophilic protein molecules; second, we used the arginine modifying reagent phenylglyoxal to increase the protein hydrophobicity and thus enhance its adherence to hydrophobic surfaces. We used scanning force microscopy to show that the glow discharge treatment favors a more homogeneous distribution and stronger adherence of the protein molecules to the graphite surface. Chemical modification of the immunoglobulin caused increased aggregation of the proteins on the surface but did not improve the adherence to graphite. On mica, clusters of modified immunoglobulins were also observed and their adsorption was reduced. These results underline the importance of the surface hydrophobicity and charge in controlling the distribution of proteins on the surface.

Preparation of isolated biomolecules for SFM observations: T4 bacteriophage as a test sample.

The T4 bacteriophage has been used to investigate protocols for the preparation of samples for scanning force microscopy in air, in order to obtaining reproducible images. The resolution of images and the distribution of bacteriophages on the substrate depends on the buffer type, its concentration, the surface treatment of substrate, and the method of deposition. The best imaging conditions for the phages require dilution in a volatile buffer at low ionic strength and adsorption onto hydrophilic surfaces. When imaging with the scanning force microscopy the quality of the images is influenced by the vertical and lateral forces applied on the sample and by the tip geometry.