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Biomedical subjects

D B Ross

Publications and source records attributed to D B Ross.

At least 19 recordsLinked to original sources
PubMed1990

Growth, feed efficiency and carcass composition of finishing Friesian steers fed the beta-adrenergic agonist L-644,969.

The beta-adrenergic agonist L-644,969 was evaluated to determine its effects on growth performance and carcass composition of Friesian steers. L-644,969 is the R,R isomer of 6-amino [[(1-methyl-3-phenylpropyl) amino] methyl]-3-pyridine methanol dihydrochloride. Four groups of 18 steers, averaging 380 kg body weight, were individually given ad libitum access to a pelleted concentrate diet that contained either 0, .25, 1.0 or 4.0 ppm L-644,969 for the final 12 wk of the finishing period. Live weight gain was not affected by L-644,969, but feed consumption was linearly reduced (5.5, 6.3 and 15.7%; P less than .01) and feed conversion efficiency was linearly increased (16, 25 and 31%; P less than .01) relative to unmedicated controls, respectively. In addition, L-644,969 quadratically increased carcass weight (3.7, 9.3 and 8.5%; P less than .01) and dressing percentage (2.7, 7.9 and 7.9%; P less than .001). The proportion of trimmed fat in the carcass was quadratically reduced (14.5, 29 and 36%; P less than .001) and yield of lean meat quadratically increased (6.7, 13 and 15.6%; P less than .001). beta-adrenergic agonist treatment altered the distribution of lean meat such that a greater (P less than .001) proportion of the total lean was in the hind portion of carcasses from treated animals. Based on these findings, we suggest that L-644,969 may have utility as an agent to improve efficiency of production of lean beef.

Adrenergic beta-Agonists↗
PubMed1989

Chemoprophylaxis and immunity to parasitic bronchitis in cattle--a field experiment comparing topical ivermectin and an oxfendazole intraruminal device.

Seeder calves infected with Dictyocaulus viviparus were used to contaminate a field divided into three similar paddocks. Twenty-four autumn-born calves were allocated to three matched groups; one group was given topical ivermectin treatments (0.5 mg/kg) at 3, 8 and 13 weeks after turnout (Day 0); each member of a second group was given an oxfendazole pulse-release intraruminal device (OPRB) at turnout; while a third group was kept as untreated controls to monitor the natural epidemiological pattern of events. Severe pasteurella pneumonia exacerbated by lungworm infection occurred in the controls after Day 24. Two died and repeated doses of antibiotic and anthelmintic therapy were necessary to save the remainder. Clinical signs were much milder in the ivermectin and OPRB groups and resolved with only a single dose of antibiotic. The OPRB group excreted some lungworm larvae at this time, but none was detected in the faeces of the ivermectin group during the grazing season. At housing, five calves from each group and four lungworm-naive calves were challenged with D. viviparus larvae. The infection became patent in all challenge-control calves, but no larvae were passed by any of the trial animals. Post-mortem worm-counts revealed percentage takes for the challenge controls, trial controls, ivermectin and OPRB groups of 16.7, 0.01, 0.9 and 0.2, respectively. All trial groups had therefore developed a substantial immunity.

Administration, Topical↗
PubMed1989

Spontaneous rupture of the diaphragm in labour: a case report.

Spontaneous rupture of the diaphragm during normal labour is extremely rare. It requires emergency surgical correction. The authors report what they believe is only the second reported case. Eleven hours after delivery of a male infant, a 27-year-old woman experienced severe epigastric pain, vomiting and dyspnea, followed by cardiopulmonary arrest. Although the ruptured diaphragm was diagnosed and repaired, she suffered severe anoxic encephalopathy and died 3 weeks after operation without regaining consciousness. Clinicians must be aware of the existence of this rare condition because failure to diagnose and treat the ruptured diaphragm will almost certainly lead to the patient's death.

Adult↗
PubMed1988

Spinous process segmental instrumentation for scoliosis.

Spinous process segmental instrumentation (SPSI) for spinal fusion was devised in 1983 by Drummond et al. in an attempt to achieve the stability of segmental fixation without the known neurologic risks of passing sublaminar wires. We used SPSI in 75 scoliosis patients. Sixty-one had idiopathic scoliosis, 12 had neurogenic scoliosis, and 2 had congenital scoliosis. There were no deep infections, pseudarthroses, or neurologic complications. Two patients experienced upper hook dislodgement with 10 degrees loss of correction. We concluded that SPSI can achieve the correction of Harrington rod instrumentation and the stability of Luque rod segmental instrumentation, without the neurologic risk of sublaminar wiring.

Adolescent↗
PubMed1987

An algorithm for planning stereotactic brain implants.

A computer software package was developed for the planning and execution of brain biopsy and radioactive implant procedures with the BRW Stereotaxic System. With the application of computer graphics and a zero-one integer variable programming algorithm, an implant plan with accompanying isodose distributions and stereotactic coordinates can be easily accomplished at the time of the operation when the computer imaging terminal and a printer/plotter is placed in the operating room.

Algorithms↗
PubMed1985

Persistent anthelmintic activity of ivermectin in cattle.

Two studies are described which demonstrate the persistent activity of ivermectin injected subcutaneously into cattle at 200 micrograms/kg in preventing the establishment of induced infections with the gastrointestinal parasites Ostertagia ostertagi and Cooperia oncophora and the lungworm Dictyocaulus viviparus. These results indicated a reduction in mean worm count compared with the control group for O ostertagi of more than 99, 45 and 94 per cent with a seven, 14 or 21 day interval between treatment with ivermectin and the administration of infective larvae, respectively, in trial 1 and more than 99, more than 99 and 99 per cent at seven, 10 or 14 days, respectively, in trial 2. Corresponding values against C oncophora were 99, 0 and 45 per cent at seven, 14 and 21 days in trial 1 and more than 99, 84 and 31 per cent at seven, 10 and 14 days in trial 2. Against D viviparus, reduction in counts were more than 99, 98 and more than 99 per cent at seven, 14 and 21 days, respectively, in trial 1 and 100, 100 and 100 per cent at seven, 10 and 14 days, respectively, in trial 2. The relevance of these results to the build-up of infective larvae on pasture and infection in cattle is discussed.

Animals↗
PubMed1978

Some actions of catechol on synaptic transmission in the isolated spinal cord of the frog.

The isolated frog spinal cord was used to investigate the synaptic effects of the convulsant agent catechol. Addition of the compound to the superfusate consistently enhanced orthodromic reflex activity recorded from ventral roots and augmented primary afferent depolarization. Concomitantly catechol altered the polarization changes produced in ventral and dorsal roots by putative neurotransmitter amino acids when these compounds were applied in Mg2+-containing Ringer. Catechol reduced the hyperpolarizations induced in motoneurons by the neutral amino acids, GABA, beta-alanine, taurine and glycine, but did not affect the depolarizations produced by the dicarboxylic amino acids, L-glutamate and L-aspartate. In contrast, catechol increased the dorsal root depolarizations elicited by both neutral and dicarboxylic amino acids and also the depolarizations produced by elevated potassium concentrations. Catechol did not bring about significant changes in the passive electrical properties of motoneurons or dorsal root fibers. In addition, it did not alter either the high affinity uptake or the depolarization-evoked release of tritiated GABA, glycine, L-glutamate and L-aspartate. It appears that the postsynaptic actions of catechol explain its ability to enhance spinal reflexes.

Action Potentials↗
PubMed1977

Analysis of fat-soluble vitamins. XVI. Antirachitic activity of 5,6-trans-vitamin D3 alone and in the presence of 5,6-cis-vitamin D3 resin, using chick bioassays.

Two biological assays were conducted in which the antirachitic activity in chicks of 5,6-trans-vitamin D3 added to feed is compared with that of 5,6-cis-vitamin D3. On the basis of the results obtained it is concluded that the relative potency of the trans isomer is, at the most, 5% and that the antirachitic activity of the trans isomer is not markedly enhanced (an increase to a relative potency of 16%, at the most) if the cis isomer is also included in the diet. The results are not conclusive on the inhibition or lack of inhibition of the antirachitic activity of 5,6-cis-vitamin D3 by the presence of 5,6-trans-vitamin D3 in the feed.

Animal Feed↗
PubMed1975

The effect of fenbendazole on nematode parasites in experimentally infected lambs.

Fenbendazole given orally to experimentally infected lambs at a dose rate of 5 mg per kg was found to be 100 per cent effective against three and 10-day larave and also against 20-day adults of H contortus, O circumcincta, N battus and T colubriformis. The same dose was also 100 per cent effective against 10-day, 17-day larvae and 27-day adult D filaria.

Animals↗