Stable transformation of rice (Oryza sativa L.) via microprojectile bombardment of highly regenerative, green tissues derived from mature seed.

A highly efficient and reproducible transformation system for rice ( Oryza sativa L. cv. Taipei 309) was developed using microprojectile bombardment of highly regenerative, green tissues. These tissues were induced from mature seeds on NB-based medium containing 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzylaminopurine (BAP) and high concentrations of cupric sulfate under dim light conditions; germinating shoots and roots were completely removed. Highly regenerative, green tissues were proliferated on the same medium and used as transformation targets. From 431 explants bombarded with transgenes [i.e. a hygromycin phosphotransferase ( hpt) gene plus one of a wheat thioredoxin h ( wtrxh), a barley NADP-thioredoxin reductase ( bntr), a maize Mutator transposable element ( mudrB) or beta-glucuronidase ( uidA; gus) gene], 28 independent transgenic events were obtained after an 8- to 12-week selection period, giving a 6.5% transformation frequency. Of the 28 independent events, 17 (61%) were regenerable. Co-transformation of the second introduced transgene was detected in 81% of the transgenic lines tested. Stable integration and expression of the foreign genes in T(0) plants and T(1) progeny were confirmed by DNA hybridization, western blot analyses and germination tests.

Persistence of the activity of topical ivermectin against biting lice (Bovicola bovis).

To assess the persistence of the activity of topical ivermectin against a natural challenge with biting lice (Bovicola bovis), 90 mixed-breed cattle that had been treated to remove lice, were blocked by bodyweight within sex and randomly allocated to three treatments: untreated control, doramectin at 200 micrograms/kg by subcutaneous injection, and ivermectin at 500 micrograms/kg by topical application. Forty-five pens were blocked into three groups of 15, and the blocks of pens were randomly allocated to three 14-day challenge periods starting 21, 28 and 35 days after treatment. There were five pens per treatment for each challenge period, and one B bovis-infested donor calf was introduced into each pen containing two principal calves at the start of the challenge period for that block of pens. The calves were examined thoroughly for B bovis seven, 14 and 21 days after the introduction of the donors. There were no significant differences between the control and doramectin groups for the numbers of animals infested, or the geometric mean louse counts at the final examination for any of the challenge periods. At the final examination for each challenge period, the louse counts of the cattle treated with topical ivermectin were all zero, and significantly (P < 0.05) fewer cattle treated with topical ivermectin were infested than either the controls or cattle treated with doramectin.

A survey on resistance to anthelmintics in sheep stud farms of southern Brazil.

A survey to investigate the status of anthelmintic resistance in 29 sheep studs in southern Brazil was conducted from March 1992 to December 1993. Compounds from three drug families (macrocyclic lactone, levamisole and benzimidazole) were evaluated concurrently on 22 of the 29 studs. On seven of these properties, resistance to all three families was declared or suspected; at 15 of the 22 studs, ivermectin was the only compound found to be effective in reducing faecal egg counts. Resistance to levamisole was detected on 22 of the 23 studs where it was evaluated and was suspected in the remaining one. The position of benzimidazoles was similar, resistance being declared or suspected on all 28 studs where they were tested. Results of larval cultures indicated that Trichostrongylus, Ostertagia and Haemonchus were the most prevalent nematode genera in the survey, with Trichostrongylus and Haemonchus being the genera associated with anthelmintic resistance.

Survey of Dirofilaria immitis (Leidy, 1856) in random source cats in metropolitan Rio de Janeiro, Brazil, with descriptions of lesions.

To evaluate the prevalence of heartworm disease in metropolitan Rio de Janeiro, RJ, Brazil, cats submitted for euthanasia were evaluated by laboratory tests and by necropsy for signs of heartworm infection. Of the 135 cats examined, one (0.8%)--a stray male from an urbanizing district--had one male worm (14.5 cm) in the left lung and showed severe muscular hypertrophy of small pulmonary arteries and arterioles with no right ventricle enlargement or passive congestion. Microfilariae were not detected in the blood of any cats. The prevalence of canine heartworm in the area from which this cat originated is estimated to be approximately 12%. The prevalence of canine heartworm in the urban area of Rio de Janeiro has been determined to be approximately 5%. It has been shown that the prevalence of feline heartworm disease parallels that in dogs, but at a lower rate. Results of this survey strongly suggest that heartworm prevention measures should be taken under consideration, especially among cats living in a high canine heartworm prevalence area.

The apolipoprotein B Q3405E polymorphism has no effect on its low-density-lipoprotein receptor binding affinity.

A better understanding of the apolipoprotein B100 (apoB100) sequences involved in binding to the low-density lipoprotein (LDL) receptor will be achieved by studying the effects of polymorphisms and rare mutations of apoB100. Upon re-examination of apoB100 DNA sequencing discrepancies, a charge-change polymorphism, Q3405E, was found in the putative LDL receptor binding domain of the protein. Positively charged lysine and arginine side chains of the protein have been demonstrated to participate in the ligand. This led us to propose that the presence of an additional negative charge in close proximity could have an impact on the binding affinity. The polymorphism is the result of a C-to-G transition at nucleotide 10422. Population screening revealed 20 of the less common glutamate alleles at an allele frequency of 0.9%. The effect of the presence of one glutamate allele on the binding affinity of LDL for the LDL receptor was investigated in seven heterozygous individuals by a competitive dual-label fibroblast binding assay. One individual who was homozygous for the glutamate allele was discovered and her LDL examined in a competitive displacement binding assay. The additional negative charge at residue 3405 had no detectable affect on the binding affinity.

Role of dietary cholesterol in the optimal diet for the treatment of hypercholesterolemia.

OBJECTIVE: This paper discusses studies in which the effects of dietary cholesterol on the plasma concentrations of lipids and lipoproteins have been evaluated in adult human subjects including patients with hypo- and hypercholesterolemia. DESIGN: The dietary studies were conducted on an outpatient basis in the Clinical Research Center. Each dietary period was four weeks in duration and an adequate washout period was interposed between each dietary phase. SETTING: A university medical centre. PATIENTS: The participants in these studies were adult men or women with hypocholesterolemia, normal volunteers or patients with primary hypercholesterolemia. INTERVENTIONS: The dietary periods consisted of three separate dietary phases in which dietary cholesterol was a single variable. The diets contained 50 mg/day of cholesterol for the low cholesterol diet, 350 mg/day for the moderate cholesterol diet and 650 mg/day for the high cholesterol diet. RESULTS: Concentrations of total and low density lipoprotein (LDL) cholesterol increased in all three patient groups from the low cholesterol to the moderate cholesterol to the high cholesterol diet but the magnitude of increase in LDL cholesterol concentrations was greater in the patients with pre-existent hypercholesterolemia and least in the patients with hypocholesterolemia. In all three patients groups an increased intake of dietary cholesterol was associated with suppression of endogenous cholesterol biosynthesis as assessed by the urinary excretion of mevalonic acid. CONCLUSIONS: An increased intake of dietary cholesterol results in increases in the plasma concentrations of total and LDL cholesterol in patients with inherently low, normal or high concentrations of LDL cholesterol but the magnitude of increase is greatest in those patients with pre-existent hypercholesterolemia. These results support the view that restriction of dietary cholesterol leads to a reduction in the plasma concentrations of total and LDL cholesterol and is an appropriate recommendation for patients with known hypercholesterolemia or patients in whom medical recommendations call for a reduction in the plasma concentrations of total and LDL cholesterol.

Activation and metabolism of benz[j]aceanthrylene-9,10-dihydrodiol, the precursor to bay-region metabolism of the genotoxic cyclopenta-PAH benz[j]aceanthrylene.

Benz[j]aceanthrylene, a cyclopentafused polycylic aromatic hydrocarbon produced in combustion emissions, possesses a bay region and an etheno bridge which may both contribute to the overall genotoxicity of the compound. In order to assess the role of activation at the bay region, the precursor epoxide benz[j]aceanthrylene 9,10-oxide, its dehydration product 10-hydroxybenz[j]aceanthrylene, the key dihydrodiol 9,10-dihydroxy-9,10-dihydrobenz[j]aceanthrylene and the bay-region diol-epoxide 7,8-epoxy-9,10-dihydroxy-7,8,9,10- tetrahydrobenz[j]aceanthrylene were evaluated in the bacterial histidine-reversion plate incorporation assay (Ames assay) with Salmonella typhimurium strain TA98. The diol-epoxide alone showed direct-acting mutagenicity (10 revertants per nmole), which was decreased by addition of exogenous metabolic activation (Aroclor 1254-treated rat-liver S9), whereas all the other compounds tested were activated by increasing concentrations of S9. The potency of the diol-epoxide was not sufficient to account for the activity of the parent compound. Identification by proton nuclear magnetic resonance and mass spectrometry of the major products of further metabolism by Aroclor 1254-treated rat-liver S9 of the bay region precursor dihydrodiol 9,10-dihydroxy-9,10-dihydrobenz[j]aceanthrylene indicated that oxidation occurred predominantly at the etheno bridge, to give 9,10-dihydroxy-9,10-dihydrobenz[j]aceanthrylene-2(1H)-one, arising by (non-enzymic) rearrangement of the etheno bridge epoxide and the tetrol 1,2,9,10-tetrahydroxy-1,2,9,10- tetrahydrobenz[j]aceanthrylene. The bay region tetrol 7,8,9,10-tetrahydroxy-7,8,9,10-tetrahydrobenz[j] aceanthrylene was observed, implying further bay-region metabolism; re-aromatization of the benzo ring to benz[j]aceanthrylene-9,10-diol also occurred. Thus oxidation at the etheno bridge accounts for the majority of the activity of benz[j]aceanthrylene and its derivatives when Aroclor 1254-treated rat-liver S9 is used for exogenous metabolic activation.

Efeito persistente de ivermectin injetável contra Dermatobia hominis / Persistent effect of injectable ivermectin against Dermatobia hominis

O presente estudo foi desenvolvido com o objetivo de determinar, sob condiçöes a campo, o efeito persistente do ivermectin injetável contra Dermatobia hominis nos bovinos, comparado com um programa de tratamento tradicional para esse parasita

Effect of antiparasitic treatment in beef replacement heifers.

Two studies were conducted in western Canada to evaluate the impact of antiparasitic treatment on weight gain and reproductive performance in beef replacement heifers from weaning to first breeding. Treatment of heifers at weaning with ivermectin increased the rate of weight gain in comparison to treatment with fenthion. The feed efficiency of ivermectin-treated animals was also significantly better than those treated with fenthion. Increased weight was associated with an increased number of animals in estrus at the end of the feeding period for heifers receiving ivermectin. We concluded that treatment with ivermectin improved feed efficiency and weight gain in heifers from weaning to breeding. In turn, this weight gain appeared to be associated with an increased number of heifers in estrus.

Synthesis and biological activity of bay-region metabolites of a cyclopenta-fused polycyclic aromatic hydrocarbon: benz[j]aceanthrylene.

The possibility of bay-region activation of the cyclopenta PAH (polycyclic aromatic hydrocarbon with a peripherally fused cyclopenta ring) benz[j]aceanthrylene (1) was investigated by synthesis and bioassay of the bay-region metabolites trans-9,10-dihydroxy-9,10-dihydrobenz[j]aceanthrylene (4), trans-9,10-dihydroxy-anti-7,8-epoxy-7,8,9,10-tetrahydrobenz[j]a ceanthrylene (2), and 9,10-dihydrobenz[j]aceanthrylene 9,10-oxide (3). The known 1,2-dihydrobenz[j]aceanthrylene-9,10-dione (5) was obtained by published methods; however, the direct route to target dihydrodiol 4, dehydrogenation of the saturated five-membered ring of 5 followed by NaBH4 reduction, gave a poor yield of 4 contaminated with tetrahydrogenated products. Acceptable yields of 4 were obtained by reduction of 5 to the corresponding tetrahydro diol, diacetylation of the diol, and dehydrogenation of the five-membered ring followed by base-catalyzed deacetylation to 4. anti-Diol epoxide 2 was generated by m-chloroperoxybenzoic acid oxidation of 4. Oxide 3 was synthesized by treatment of the monotosylate of 4 with NaOH in monoglyme. Diol epoxide 2 was an active mutagen in Salmonella typhimurium strain TA98 in the absence of metabolic activation, 3 showed marginal activity, while 3 and 4 were mutagenic with metabolic activation. These results coupled with previous studies support activation of benz[j]aceanthrylene via both 2 and cyclopenta ring epoxidation.

Comparison of ivermectin, oxibendazole, and pyrantel pamoate in suppressing fecal egg output in horses.

Thirty resident horses at a boarding stable in Alberta were used to evaluate the relative efficacies of ivermectin, oxibendazole, and pyrantel pamoate in reducing fecal egg output in adult horses under routine management conditions during spring and early summer, and to more clearly define the duration of suppression of fecal egg production following anthelmintic treatment. Horses were blocked according to pretreatment egg counts and randomly assigned to one of three treatments: pyrantel pamoate at 6.6 mg/kg body weight; oxibendazole at 10 mg/kg body weight; or ivermectin at 200 mug/kg body weight. All treatments were administered orally as a paste on day 0.Fecal samples were collected for examination by the modified Wisconsin procedure before treatment, and then at 4-11 day intervals up to day 72.Very few if any strongyle eggs were found in the feces of any horses up to day 35. On days 42, 50 and 57, the geometric mean egg count for the ivermectin group was significantly (p<0.05) lower than that for the oxibendazole or pyrantel pamoate groups. Based on a survival curve analysis of the data, the mean number of days for recurrence of eggs in the feces was significantly longer for the ivermectin group than for the oxibendazole and pyrantel pamoate groups.Under conditions encountered in this study, the posttreatment interval to resumption of fecal egg out-put in horses treated with ivermectin was eight to nine weeks, compared with five to six weeks for horses treated with oxibendazole or pyrantel pamoate.

Comparative cost-effectiveness of ivermectin versus topical organophosphate in feedlot calves.

A study was conducted in a commercial feedlot in western Canada to evaluate the impact of treatment with ivermectin versus a topical organophosphate on growth rate and feed efficiency in calves entering a feedlot at an average 275 kg liveweight.A total of 9527 head of cattle was used. Variables measured included average daily gain, average days occupation, and feed conversion.Ivermectin treated animals gained an average 0.08 kg per day more than those treated with topical organophosphate. In addition, they required an average 0.23 kg less feed/kg gain. Based on an average 227 kg of gain, this would result in 11 fewer days occupation and 52.3 kg less feed for ivermectin treated animals. This equaled a net benefit of $7.04 per head over treatment costs for ivermectin treatment versus topical organophosphate.

Critical test and safety evaluations of an oral paste preparation of mebendazole and trichlorfon in horses.

Critical tests were done on 24 naturally parasitized horses to compare the antiparasitic activity of an oral paste preparation of mebendazole and trichlorfon with that of the marketed powder formulation. Each formulation was administered at the recommended dosages of 8.8 mg of mebendazole and 40 mg of trichlorfon/kg of body weight. Efficacy of the paste formulation ranged from 97.7% to 100% against 2nd- and 3rd-stage Gasterophilus spp, adult Strongylus vulgaris, S edentatus, Parascaris equorum, small strongyles; and larval and adult forms of Oxyuris equi. Adverse effects were generally limited to slight softening of the feces. Mild and transient restlessness or sweating were also observed in 2 of 12 horses treated with the paste formulation. The toxic effects of the paste, administered at 2.2 times the therapeutic dose, were examined in 6 horses and compared with the effects of a nonmedicated paste, administered in similar volumes to 6 other horses. Drug-related changes were not detected in clinical chemical analyses, hematologic values, or liver function tests. Transient clinical signs of organophosphate toxicosis (primarily the passage of loose feces) and prolonged inhibition of erythrocyte cholinesterase activity were evident within 1 hour after drug treatment. These effects were similar to those reported for the 2.2 X dose of marketed powder formulation.

Seasonal comparisons of anthelmintic activity of levamisole pour-on in cattle in the USA.

Anthelmintic activity of a pour-on formulation of levamisole, applied during warm weather (16 degrees to 36 degrees C) at 10 mg/kg bodyweight, was evaluated in groups of naturally parasitised calves. This activity was compared to that obtained in similar groups of calves treated in the winter (-4 degrees to +7 degrees C). Controlled efficacy of the pour-on formulation was determined for each season by comparing mean worm burdens in treated calves sacrificed seven to nine days after treatment to non-treated controls. In these trials, burdens of Bunostomum phlebotomum, Cooperia species, Haemonchus placei, Nematodirus species, Oesophagostomum radiatum, Ostertagia ostertagi and Trichostrongylus axei in treated calves were reduced by 83.3 to 100 per cent in the summer and 89.2 to 100 per cent in the winter. Field investigations at nine locations across the USA compared changes in faecal egg counts for cattle treated and evaluated during warm summer months (27 degrees to 36 degrees C) to those treated during cold winter months (-18 degrees to +10 degrees C). Overall, faecal egg counts were reduced by 90.2 per cent in the summer trials and 94.0 per cent in the winter trials. The results of these trials indicate that there is no seasonal variation in the anthelmintic activity of this pour-on formulation of levamisole.

Activity of closantel against experimentally induced Fascioloides magna infection in sheep.

The efficacy of closantel against experimentally induced Fascioloides magna infection in sheep was studied. In each of 3 experiments, closantel was administered 8 weeks after the sheep were given (oral inoculation) 100 metacercariae of F magna. In the 1st experiment, closantel was given orally to 5 groups of 6 sheep each at dosages of 0 (nontreated control), 5, 7.5, 10, and 15 mg/kg of body weight. In the 2nd and 3rd experiments, groups of 10 or 12 sheep were treated to confirm the efficacy of the previously determined optimal dosage of 15 mg/kg. An additional group of sheep (n = 10) was used in the 3rd experiment to evaluate the efficacy of closantel given IM at a dosage of 7.5 mg/kg. Closantel given orally at a dosage level of 15 mg/kg was highly effective (94.6% to 97.7%) in reducing F magna burdens. Also, pathologic scores associated with the F magna infection were reduced by 81.3% to 92.6% in sheep given this dosage of closantel. Efficacy of the IM administered dosage of 7.5 mg of drug/kg was equivalent to that of the 15 mg/kg oral dosage. Other than mild, transient lameness of the limbs which were injected with the drug (group 10), side effects were not observed.

Activity of closantel in the prevention of Gasterophilus and Strongylus vulgaris larval infections in equine foals and yearlings.

Two controlled tests were conducted in equine foals and yearlings to determine the optimal oral dosage and the duration of activity of closantel for the prevention of Gasterophilus spp larval infections. Additional data were collected on the activity of closantel against Strongylus vulgaris larval infections. In experiment 1, 12 foals and 12 yearlings were equally allocated to 4 experimental groups, and were given oral treatments with closantel at dosages of 0 (nontreated controls), 2, 5, or 8 mg/kg of body weight every 2 months during bot season. The foals and yearlings were allowed to graze on open pasture throughout the experiment to provide a natural source for bot and helminth infections. All animals were euthanatized and necropsied 6 weeks after the final treatment. Closantel was highly effective (98.6% to 100%) at all doses in preventing Gasterophilus spp larval infections in the foals, but only the 8 mg/kg dose had significant (P less than 0.05) activity (99.7%) in the yearlings. This dose also significantly reduced the numbers of 4th-stage and immature adult S vulgaris (86.0%) in the mesenteric arteries as compared with nontreated controls. In experiment 2, 9 foals and 9 yearlings received a single oral treatment of 8 mg of closantel/kg of body weight; 3 foals and 3 yearlings were kept as nontreated controls. Groups of 6 treated (3 foals, 3 yearlings) and 2 control (1 foal, 1 yearling) animals were euthanatized and necropsied 1, 2, and 3 months after treatment. Closantel remained effective for 2 months in preventing infections of G intestinalis larvae in these foals and yearlings. Clinical signs of toxicosis were not observed in the treated animals of either study.

Controlled and clinical evaluations of the anthelmintic activity of a levamisole pour-on formulation against gastrointestinal nematodes in cattle.

Beef-type calves (n = 107) with naturally occurring helminth infections were used in a series of 3 controlled experiments to study the anthelmintic activity of a new pour-on formulation of levamisole. In the 1st experiment, the efficacy of a single treatment of levamisole pour-on at a rate of 10 mg/kg of body weight was determined, using a placebo pour-on in a similar volume as a control. In the 2nd experiment, calves were treated with levamisole pour-on at doses 0 (nontreated control), 7.5, 10, or 12.5 mg/kg of body weight. In the 3rd experiment, the anthelmintic efficacy of the optimal dose of levamisole pour-on (10 mg/kg of body weight) was compared with that of injectable levamisole at the recommended rate (6 mg/kg of body weight). In all 3 studies, levamisole pour-on, at a dosage of 10 mg/kg of body weight, was efficacious (90% to 100%) against the adult forms of Trichostrongylus axei, Haemonchus placei, Ostertagia ostertagi, Cooperia spp, Oesophagostomum radiatum, Nematodirus spp, and Bunostomum phlebotomum. Efficacy was moderate to good against Capillaria bovis, and poor or inconsistent against Strongyloides papillosus and Trichuris ovis. Clinical tests of anthelmintic efficacy and local tolerance of levamisole pour-on were conducted in 371 beef and dairy cattle in Mexico. Fecal egg counts were consistently reduced 2 weeks after a single application of levamisole pour-on at a dosage of 10 mg/kg of body weight. Local reactions were limited to various degrees of dry hair coat for up to 2 weeks at the application site. Hair loss or skin abnormalities were not observed in any of the treated cattle.

Anthelmintic efficacy of mebendazole suspension against induced helminth infections in South African sheep and cattle.

Critical controlled tests were performed in 157 sheep (8 experiments) and 34 cattle (2 experiments) to evaluate the anthelmintic activity of mebendazole suspension, administered intraruminally via a stomach tube at a dosage rate of 15 mg of mebendazole/kg of body weight, against induced infections of immature and adult stages of commonly encountered nematode parasites in South Africa. In the sheep, the controlled efficacy of mebendazole suspension was good to excellent (90.1% to 100%) against all stages of Haemonchus contortus, Trichostrongylus colubriformis, Gaigeria pachyscelis, Ostertagia circumcincta, Nematodirus spathiger, and Chabertia ovina species. Mebendazole was also highly effective (97.3% to 99.9%) against 4th, 5th, and adult stages of Oesophagostomum columbianum and 5th-stage and adult Dictyocaulus filaria. Moderate activity was obtained (79.8% to 82.2%) against 3rd-stage O columbianum, 3rd- and 4th-stage D filaria, and 5th-stage and adult Strongyloides papillosus. In the cattle, mebendazole was effective (91.5% to 100%) against 4th-stage and adult H placei, Cooperia pectinata, Bunostomum phlebotomum, and Oesophagostomum radiatum species, but did not exhibit any appreciable activity (27.3% to 41.5%) against 4th-stage and adult O ostertagi.

Activity of flubendazole against developing stages of Dirofilaria immitis in dogs.

A formulation of flubendazole was studied to determine the activity against developing stages of Dirofilaria immitis in artificially infected pups. Flubendazole suspension was administered subcutaneously at a dose rate of 50 mg/kg of body weight once a day for 1, 3, or 5 consecutive days at various times during the experimental period. The pups were necropsied 6 months after the experimental infection, and the heart and pulmonary arteries were examined for adult worms. Optimal activity was obtained when flubendazole suspension was administered subcutaneously for 5 consecutive days, either 1 or 2 months after infection. The formation of encapsulated deposits, containing white viscous fluid, was observed at the injection sites of all treated pups.