Concurrent Trials Research Articles

A comparison of the morantel sustained-release bolus with conventional drenching for the control of gastro-intestinal nematodes in grazing calves

A comparison was made of the parasitological and production responses to the prophylactic (summer) and combined prophylactic and therapeutic (summer/autumn) administrations of the morantel intraruminal, sustained-release bolus (MSRB) with responses to conventional drenching in grazing dairy calves over an 8-month period. The MSRB was designed to release morantel tartrate at 150 mg/day for 90 days. In two concurrent trials, groups of calves grazed separate replicated pastures. In Trial 1, the combined summer (December) and autumn (March) administration of the MSRB was compared with a programme of six drenches (oxfendazole at 4.53 mg/kg) at 28-day intervals from December to May. In Trial 2, the summer administration of the MSRB was compared with a programme of three autumn drenches (oxfendazole) at 28-day intervals from March to May. There were no significant between-treatment differences in mean liveweight gain in either trial. In both trials, the low numbers of eggs passed by the MSRB-treated animals during summer (maximum mean 62 eggs per gram of faeces) were sufficiently high to produce a modest autumn larval peak (maximum 1990 larvae/kg herbage). In Trial 2, the summer use of the MSRB resulted in an 83% reduction in peak larval availability compared with that on pastures grazed by untreated calves during summer. Only the 6-drench regimen (Trial 1) prevented the accumulation of appreciable worm burdens of early 4th stage Ostertagia spp.

Classical conditioning of the rabbit’s nictitating membrane response to CS compounds: Effects of prior single-stimulus conditioning

Two experiments were conducted to determine the effects of prior single-stimulus training on classical conditioning to a compound and its components and subsequent component extinction of the rabbit’s nictitating membrane response. Experiments 1 and 2 found that prior single-stimulus training interfered with acquisition of responding to a second stimulus during compound conditioning and retarded responding to the second stimulus during extinction. Moreover, Experiment 2 revealed that the interference effects of prior single-stimulus training on response acquisition to a second stimulus were attenuated by the addition of concurrent training trials to the second stimulus. The results are discussed in terms of theories of stimulus selection.

Radiotherapy and bleomycin-containing chemotherapy in the treatment of advanced head and neck cancer: Report of six patients and review of the literature

In an effort to improve the complete remission rate achievable with bleomycin and cisplatin, administered prior to radiotherapy in previously untreated patients with unresectable epidermoid carcinoma of the head and neck, we initiated a pilot study employing simultaneous chemotherapy and radiotherapy. Six patients were treated with bleomycin (B) 15 mg i.m. t.i.w. 30–60 minutes prior to radiotherapy (RT) treatment with conventional fractionation, 180–200 rad/fx, 5 fx/week. During interruptions in B + RT for healing of mucocutaneous reactions, patients received cisplatin 40 mg/m 2 once weekly. Toxicity included severe mucositis within the radiation port in all patients, three episodes of infection, and significant myelosuppression in one patient. Transient mild serum creatinine elevation occurred in four patients. Three patients did not complete treatment because of severity of toxicity. Response was: primary— 4 6 CR, 1 6 PR; regional nodes— 1 5 CR, 4 5 PR. Review of the literature of concurrent bleomycin and radiotherapy trials in head and neck cancer indicates that other investigators have encountered severe toxicity using bleomycin dose and radiation fractionation schedules similar to ours. Toxicity may be reduced when lower doses of concurrent bleomycin and/or alternative radiation fractionation schedules are employed. Although results of uncontrolled trials suggest a possible therapeutic advantage to treatment with the combination compared to radiotherapy alone, this has not clearly been established in the four randomized trials reviewed.

Children's rating responses as related to amount and recency of stimulus familiarization and stimulus complexity

Seventy-two fifth- and sixth-grade children were given 16 exposures of each of four stimuli (64 total exposures) in a familiarization phase. For half the Ss, the stimuli were Welsh figures that had been previously rated by adults as simple, the remaining Ss being exposed to Welsh figures rated as complex by the same adults. Four times during this familiarization phase, Ss were given Concurrent Test trials in which they rated one of the familiar stimuli and one stimulus they had not yet seen, a nonfamiliar stimulus. In what was termed the Post Test, one-third of the Ss rated the same four familiar stimuli and four different nonfamiliar stimuli 5 min after the familiarization phase, another third 2 days after, and the final third 7 days after. Nonfamiliar stimuli received higher ratings than did familiar in both the Concurrent and the Post Test, the magnitude of this effect not depending on the complexity of the stimuli or on the length of delay between familiarization and the Post Test.

Modulatory effects of preoptic stimulation on hypothalamically-elicited attack in cats

Previous ablation studies implicate the preoptic area as having an inhibitory influence on emotional behavior, while stimulation studies have elicited attack from the preoptic region. In the present investigation, stimulation of the medial preoptic area and a restricted, medial, portion of the lateral preoptic area elicited directed attack on a rat while periventricular preoptic stimulation elicited at most pupil dilation. Concurrent stimulation of medial or mediolateral preoptic sites, and sites in the lateral hypothalamus from which attack could be elicited, facilitated attack. Pairing periventricular preoptic with hypothalamic stimulation suppressed attack, increasing latencies during both individual hypothalamic and concurrent stimulation trials, thus having a long-term effect.

The Measurement of Nutritive Quality in a Bluegrass Pasture Using In Vivo and In Vitro Techniques

A series of trials was carried out to determine the influence of growth phase (first vs. regrowth), stage of maturity, nitrogen fertilization (60 lb. N vs. 240 lb. N) and cutting management (continuous growth vs. interval clipping) on the digestibility of Kentucky bluegrass clipped and fed in the fresh form to sheep. Concurrent laboratory trials were performed to determine the feasibility of predicting digestibility coefficients by means of in vitro techniques, and to examine the influence of method of preparation (as fresh, freeze-dried or oven-dried grass) of the sample and the source of rumen fluid inoculum (from grass or hay-fed sheep) on the in vivo-in vitro relationship. Significant differences in both animal and in vitro digestibility coefficients were obtained due to pasture treatment effects, and there were also significant differences in in vitro digestibility caused by method of preparation of the grass and sources of inoculum. The correlations between in vivo dry matter and cellulose digestibility and the in vitro dry matter or cellulose digestibility of either fresh, freeze-dried or oven-dried grass, using either grass or hay inocula, were found to be highly significant. This indicates that any combination of preparation and inoculum might justifiably be used in the prediction of animal digestibility coefficients of dry matter or energy. However, analysis of the data suggested that several of the variable factors examined might significantly affect the in vivo-in vitro digestibility relationship. Protein digestibility in vivo was found to be as highly related to protein content of the forage as to any measure of in vitro protein digestion. Analysis of volatile fatty acid distribution in the rumen or in in vitro fermentation mixtures indicated that (1) molar proportions of acids in the rumen of grass-fed sheep differed from those in sheep maintained on hay, containing relatively less acetic and more propionic acid, (2) acetic acid increased and propionic acid decreased in the rumen contents with increasing maturity of the herbage, (3) vegetative growth in August and September produced relatively less propionic acid than a comparable growth in May, (4) there was no apparent effect of level of nitrogen fertilization on the distribution of acids in the rumen, (5) molar proportions of volatile fatty acids produced at 36 hr. in vitro were similar to those found in the rumen fluid of sheep fed the same substrate, although there was a tendency for higher levels of propionic acid to be present in vitro, and (6) method of preparation of the sample did not affect in vitro distribution of volatile fatty acids; however, source of inoculum was a significant factor.