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B R Cook

Publications and source records attributed to B R Cook.

16 recordsLinked to original sources
PubMed1998

Comparison of LC detection methods in the investigation of non-UV detectable organic impurities in a drug substance.

HPLC Analysis with different detection methods was shown to be essential in the separation and identification of unknown organic impurities in a drug substance. The impurities were found to exhibit very weak or no response to standard ultraviolet (UV) absorption detection. LC-MS, LC-NMR, indirect, refractive index and evaporative light-scattering detection were used to quantify and identify the impurities in this specific case. The drug substance studied was found to be an ideal analyte for demonstrating the advantages and limitations of several chromatographic detection systems for impurity profile analysis.

Chromatography, High Pressure Liquid↗
PubMed1996

The pigeon's recognition of drawings of depth-rotated stimuli.

Four experiments used a four-choice discrimination learning paradigm to explore the pigeon's recognition of line drawings of four objects (an airplane, a chair, a desk lamp, and a flashlight) that were rotated in depth. The pigeons reliably generalized discriminative responding to pictorial stimuli over all untrained depth rotations, despite the bird's having been trained at only a single depth orientation. These generalization gradients closely resembled those found in prior research that used other stimulus dimensions. Increasing the number of different vantage points in the training set from one to three broadened the range of generalized testing performance, with wider spacing of the training orientations more effectively broadening generalized responding. Template and geon theories of visual recognition are applied to these empirical results.

Animals↗
PubMed1993

Mycobacterium hiberniae sp. nov.

Strains of a new type of slowly growing scotochromogenic, rose-pink-pigmented mycobacterium were isolated repeatedly from sphagnum vegetation, true moss, and soil in Ireland. These strains grew at 22, 31, and 37 degrees C but not at 45 degrees C and possessed acid phosphatase and arylsulfatase activities. They reduced nitrate, tolerated 0.1% NaNO2, did not split amides, and were resistant to most of the antituberculous drugs tested, except ethambutol. They did not form acid from glucose and mannose. Their internal phenetic similarity was 97.08% +/- 2.07%. The whole mycolate pattern confirmed the homogeneity of the taxa sharing similar mycolate types with several other mycobacterial species. However, on the basis of the nature of the major pyrolysis esters, the taxon appeared unique. The phylogenetic analysis based on evolutionary distance values revealed that the strains belong to a new species of slowly growing mycobacteria. The DNA-DNA hybridization values confirmed that these strains differ significantly from Mycobacterium nonchromogenicum, M. terrae, M. triviale, and M. thermoresistibile. The strains produced a unique rose-pink pigment and were nonpathogenic for mice, guinea pigs, and rabbits, but they provoked a nonspecific hypersensitivity reaction to bovine tuberculin in guinea pigs and cattle. Hence, they are considered a member of a new species of nonpathogenic slowly growing mycobacteria, for which the name Mycobacterium hiberniae is proposed. Strain Hi 11 is the type strain, a culture of which has been deposited in the American Type Culture Collection as strain ATCC 49874.

Bacterial Typing Techniques↗
PubMed1993

Effects of selection strategies using heifer pelvic area and sire birth weight expected progeny difference on dystocia in first-calf heifers.

A stochastic computer simulation model was developed to evaluate the effects of selection strategies based on heifer pelvic area and sire birth weight EPD on dystocia in first-calf heifers. Parameters and relationships used were taken from the literature. Unrelated sets of yearling heifers were simulated. Replacement heifer selection was based on breeding the top 40, 60, 80 or 100% (i.e., no selection) of available heifers as determined by yearling pelvic area (YRLGPA). Selected heifers were bred to bulls that were selected based on EPD for birth weight (SEPD). Levels of SEPD were -2.7, -1.8, -.9, 0, .9, and 1.8 kg. Simulated responses included precalving pelvic area, calf birth weight, calving difficulty score (1, 2, 3, 4), and incidence of dystocia (0, 1). Both measures of dystocia were predicted from the ratio of precalving pelvic area to calf birth weight. Simulated data were analyzed using least squares procedures. The effects of SEPD were significant (P < .05) for birth weight, calving difficulty score, and the frequency of dystocia. Differences among levels of heifer selection for YRLGPA were significant for YRLGPA, precalving pelvic area, birth weight, and calving difficulty score but not for the frequency of dystocia. Based on partial regressions calculated from weighted replication means, a 1-kg decrease in SEPD will decrease average calving difficulty score by .12 units and decrease the frequency of dystocia by 4%, whereas each 10% increase in selection pressure on YRLGPA will reduce the average calving difficulty score by only .02 units and have no detectable effect on the frequency of dystocia.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1991

The epidemiology of Echinococcus granulosus in the U.K. VIII. The structure of adult colonies of E.g. equinus say in farm dogs in Wales.

The status of Echinococcus granulosus equinus in farm dogs was examined in two valleys in South Powys, Wales. In one valley 76% of the dogs examined were infected, and there was at least one infected dog on every farm except one. In the second valley 49% of the dogs were infected. The structure of natural adult colonies of Echinococcus is described, and the population dynamics of the parasite in the U.K. is discussed. Every colony in the dogs, excepting the very smallest and the very youngest, consists of parasites at several stages of development. Most colonies comprise less than 20 worms. Colony density is greatest about the second or third eighth of the total length of the small intestine. The general characteristics of a colony (other than number) are reflected in the characteristics of the group of worms 'resident' in each successive eighth of the small intestine. Neither the age nor the sex of the host has any obvious effect on the incidence or the size of the colony, its development, or the ultimate infectivity of the colony. The parasites continue to grow throughout life, and growth may be largely independent of the worms' development. As a result, their length is very variable. The number of eggs in each gravid proglottid varies considerably, from 12-1626. All the evidence available and derived from the study of natural populations confirms that E. granulosus is an obligate self-fertilizing hermaphrodite, and that serial development of gravid proglottids does not occur.

Animals↗
PubMed1989

The epidemiology of Echinococcus granulosus in Great Britain. V. The status of subspecies of Echinococcus granulosus in Great Britain.

Twenty-five years ago Williams and Sweatman suggested that in Great Britain there are two subspecies of Echinococcus granulosus--E. granulosus granulosus and E. granulosus equinus. Echinococcus granulosus granulosus does not mature either in foxes or in horses: E. granulosus equinus will mature in either. The prepatent period of E. granulosus granulosus in the definitive host is about 42 days while that of E. granulosus equinus is about 70 days. Each subspecies has a characteristic morphology. More recently, in the course of seven experiments, dogs, red foxes (Vulpes vulpes crucigera), arctic foxes (Alopex lagopus), badgers (Meles meles), domestic ferrets and domestic cats have been infected with protoscoleces derived from hydatid cysts of human, equine and ovine hosts from different regions of England and Wales. Transmissions to horses and sheep were always succeeded by the development of viable hydatid cysts; transmissions to dogs and foxes, by the development of gravid adults. The prepatent period in both dogs and foxes was invariably about 70 days (or longer) and the morphology of all the adult parasites in these definitive hosts was characteristic of E. granulosus equinus. All the evidence derived from these experiments supports the view that there is, in Great Britain, but one subspecies of E. granulosus. That one subspecies is E. granulosus equinus. It infects dogs, red foxes, arctic foxes (experimentally), cats (experimentally), humans, sheep, goats, horses, donkeys, pigs, cattle, roe deer and reindeer (in Scotland). Attempts to transmit E. granulosus to badgers and domestic ferrets were unsuccessful. Of 123 cats infected with protoscoleces of horse origin, one gravid adult parasite was recovered from one animal.

Animals↗
PubMed1988

Mycobacteria in pond waters as a source of non-specific reactions to bovine tuberculin in New Zealand.

When 71 samples were collected from ponds throughout New Zealand, 35 (49.3%) were found to contain mycobacteria. The majority of these strains (62.9%) belonged to a homogeneous group (tentative designation H-Group, which differed from any known mycobacterial species. Mycobacteria of this H-group had also been found in sphagnum vegetation growing in the immediate vicinity of many of the ponds. H-Group mycobacteria induce sensitization in guinea pigs against bovine tuberculin. The PPD sensitin prepared from these mycobacteria gave rise to larger reactions in guinea pigs than did bovine tuberculin when used in the same concentrations (500 and 50 TU). The possible sensitization of cattle to bovine tuberculin via drinking water containing H-Group mycobacteria, is discussed. The larger size of the delayed hypersensitivity reactions in guinea pigs using the same concentrations of bovine and homologous tuberculin, suggests that comparative intradermal testing might enable this non-specific reaction to be distinguished from the specific reaction developed during bovine tuberculosis infection in cattle.

Journal Article↗
PubMed1987

Malignant fibrous histiocytoma of the clivus: case report.

A case of malignant fibrous histiocytoma of the clivus in a 2 1/2-year-old boy is reported. There are no prior reports of this tumor in this location. The child was treated with operation, radiation therapy, and chemotherapy. The tumor recurred locally 21 months later. The recurrence was palliated by operation and chemotherapy, permitting an additional 20-month survival.

Child, Preschool↗
PubMed1984

Tic convulsif: results in 11 cases treated with microvascular decompression of the fifth and seventh cranial nerves.

The syndrome of tic convulsif consists of ipsilateral concurrent trigeminal neuralgia and hemifacial spasm. Since Cushing's 1920 description of this syndrome in three patients, 37 additional cases have been reported in the world literature. Of the 15 with adequate operative descriptions, 10 had vascular abnormalities and five had tumors. The authors report 11 cases of tic convulsif treated by microvascular decompression of both the fifth and seventh cranial nerves. At operation, 21 of 22 nerves were found to have root entry zone vascular compression. One trigeminal nerve was considered normal. One seventh nerve had a tumor displacing the anterior inferior cerebellar artery into its root entry zone. The average follow-up period in this series was 6 years 2 months (range 1 to 8 1/2 years). Eight patients (73%) were pain-free, two (18%) had frank recurrences, and one (9%) had mild discomfort. Eight patients (73%) were totally free of facial spasm, and two others (18%) had only a trace of residual spasm. These results are comparable to those achieved by treating the individual syndromes with microvascular decompression. Therefore, microvascular decompression of both the fifth and seventh cranial nerves is recommended as the treatment of choice in tic convulsif.

Aged↗