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Biomedical subjects

G Olson

Publications and source records attributed to G Olson.

At least 55 records · Page 3Linked to original sources
PubMed1978

Effect of 6-amino-9-(substituted benzyl)purines on oocyst sporulation.

A series of experiments have been conducted utilizing 11 strains of Eimeria representing 4 of the major species to measure the effect of arprinocid [6-amino-9-(2-chloro-6-fluorobenzyl)purine] and the dichloro analog L-628,914 [6-amino-9-(2,6-dichlorobenzyl)purine] on oocyst sporulation. The results of these studies show that oocysts harvested from chickens fed graded levels of these compounds and infected with E. acervulina, E. maxima, E. necatrix, or E. tenella have a decreased capacity to sporulate. This effect was observed against each of the species of Eimeria tested at levels well below the proposed use level of 60 ppm to 70 ppm of arprinocid.

Adenine↗
PubMed1978

Efficacy of arprinocid (MK-302) against Eimeria species in broilers.

Eight floor pen trials were conducted to determine the effect of arprinocid on the weight, feed efficiency, and histological lesions of broiler chickens exposed to coccidiosis. In three trials, the levels of arprinocid were 0, 40, 60, 70, 80, and 90 ppm, and in the other five trials, 0, 50, 75, and 100 ppm. Histological lesions were significantly (P less than .05) reduced in the medicated birds. Weights were not significantly (P less than .05) different between birds given 40, 60, or 70 ppm in the first series of trials no 50 and 75 ppm drug in the second and third series, although in both series the treated birds were significantly (P less than .05) heavier than the control birds. Feed efficiency was improved by all levels of arprinocid in the first and third series of trials and by 75 ppm in the second series.

Adenine↗
PubMed1978

Battery efficacy studies with arprinocid against field strains of Coccidia.

Graded levels of 9-[2-chloro-6-fluorophenyl)methyl]-9H-purin-6-amine (arprinocid) ranging from 30 ppm to 90 ppm in the diet have been tested for anticoccidial efficacy in controlled battery experiments against 20 field isolates of coccidia. These isolates, representing five major species of Eimeria, were collected from various geographic locations and all but one were found to be resistant to one or more of the currently marketed products. Arprinocid prevented mortality, increased weight gains, and reduced or eliminated intestinal lesions and oocyst production. A level of 60 ppm arprinocid provided adequate control of all isolates and no evidence of cross resistance was observed between arprinocid and the marketed products tested. On the basis of these studies, it is concluded that arprinocid at levels of 60 ppm to 70 ppm is effective in controlling coccidiosis in broilers, even that caused by isolates refractory to many of the marketed products.

Adenine↗
PubMed1977

Anticoccidial 1-substituted 4(1H)-pyridinone hydrazones.

4-Chlorobenzaldehyde 1-(4-chlorophenyl)-4(1H)-pyridinylidene hydrazone fluorusulfonate (4) was found to have excellent anticoccidial activity in chickens. The synthesis and biological evaluation of related analogues are presented. Presumably 4 shares a common mechanism of action with robenidine (25) since it was not active on a robenidine tolerant strain of E. tenella. Structural comparisons of the two molecules are presented.

Animals↗
PubMed1977

Comparison of anticoccidial efficacy, resistance and tolerance of narasin, monensin and lasalocid in chicken battery trials.

The anticoccidial efficacy, host tolerance, and projected resistance development of the three polyether antibiotics, monensin, narasin, and lasalocid were compared. The efficacy of narasin against different coccidial strains was found to parallel that of monensin in as much as strains which were refractory to monensin were also refractory to narasin. In contrast, lasalocid easily controlled some strains which were not well controlled by either narasin or monensin and failed to control one strain readily controlled by these two antibiotics. In growing chicks, lasalocid at the projected use level of 75 p.p.m. and narasin at an efficacious level of 100 p.p.m. were both better tolerated than monensin at the recommended use level of 121 p.p.m. The frequency of mutants resistant to each of these polyether compounds was found to be less than 8.6 X 10(-9) per drug sensitive oocyst for one strain of Eimeria tenella. This corresponds to less than 0.036 and 0.148 as frequent as mutants of this strain resistant to glycarbylamide or to amquinate, respectively.

Animals↗
PubMed1977

Anticoccidial and tolerance studies in the chicken with two 6-amino-9-(substituted benzyl)purines.

Initial assays of 6-amino-9-(2-chloro-6-fluorobenzyl) purine (MK-302) and 6-amino-9-(2,6-dichlorobenzyl)purine (coded L-628,914) showed potential as anticoccidial agents on the basis of broad-spectrum activity and safety. In battery efficacy studies, dietary levels of 60 to 70 p.p.m. and above MK-302 and 45 to 60 p.p.m. L-628,914 proved to have excellent broad-spectrum anticoccidial activity in chickens given heavy exposure to virulent field isolates of coccidia. Eight-week floor-pen tolerance trials showed that the maximum tolerated diet concentration (MTC) of MK-302 was approximately 95 p.p.m. while the MTC of L-628,914 was approximately 60 p.p.m. Dietary relationships (p.p.m. MK-302:p.p.m. L-628,914 for equivalent effects) derived from the efficacy and tolerance results were 1.2:1 and 1.6:1 respectively and clearly demonstrated a higher therapeutic ratio for MK-302.

Adenine↗
PubMedDate not supplied

Uterine electromyography and light-induced fluorescence in the management of term and preterm labor.

OBJECTIVE: Understanding the physiology of the uterus and cervix during term and preterm parturition is crucial for developing methods to control their function and is essential to solving clinical problems related to labor. To date, only crude, inaccurate, and subjective methods are used to assess changes in uterine and cervical function in pregnancy. METHODS: In the past several years, we have developed noninvasive methods to quantitatively evaluate the uterus and cervix based on recording of uterine electrical signals from the abdominal surface (uterine electromyography) and measurement of light-induced fluorescence (LIF) of cervical collagen (Collascope), respectively. Both methods are rapid and allow immediate assessment of uterine contractility and cervical ripening. RESULTS: Studies in animals and humans indicated that uterine and cervical performance can be monitored successfully during pregnancy using those approaches and that these techniques can be used during labor to better define management in a variety of conditions associated with labor. CONCLUSION: The potential benefits of the proposed instrumentation and methods include reducing the rate of preterm delivery, improving maternal and perinatal outcome, monitoring treatment, decreasing cesarean rate and providing research methods to understand uterine and cervical function.

Animals↗