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Biomedical subjects

C M Morrison

Publications and source records attributed to C M Morrison.

10 recordsLinked to original sources
PubMed1998

Real age-of-acquisition effects in lexical retrieval.

Previous research on the effects of age of acquisition on lexical processing has relied on adult estimates of the age at which children learn words. The authors report 2 experiments in which effects of age of acquisition on lexical retrieval are demonstrated using real age-of-acquisition norms. In Experiment 1, real age of acquisition emerged as a powerful predictor of adult object-naming speed. There were also significant effects of visual complexity, word frequency, and name agreement. Similar results were obtained in reanalyses of data from 2 other studies of object naming. In Experiment 2, real age of acquisition affected immediate but not delayed object-naming speed. The authors conclude that age-of-acquisition effects are real and suggest that age of acquisition influences the speed with which spoken word forms can be retrieved from the phonological lexicon.

Adult↗
PubMed1996

Ceratomyxa drepanopsettae in the gallbladder of Atlantic halibut, Hippoglossus hippoglossus, from the northwest Atlantic Ocean.

Trophozoites of Ceratomyxa drepanopsettae Averintsev, 1907 (Myxosporea: Ceratomyxidae) containing prominent refractile granules were found in the gallbladders of all but one of eight halibut, the exception being a single juvenile. They ranged in shape and size from globular forms 5-10 micron in diameter, to rounded structures with pseudopodia and one or more processes that were up to 500 micron in length and packed with refractile granules. Some trophozoites were free in the bile, while others were attached to the epithelium of the gallbladder wall by pseudopodia which extended between the microvilli. Many free trophozoites were attached to each other by septate junctions between their pseudopodia. There were small cylindrical papillae on the surface of the trophozoites, and the rounded portions contained two vegetative nuclei, generative cells (some attached by junctions) and, in many cases, feeding vacuoles. During sporogony, a binucleate sporoplasmic cell and the capsulogenic cells of some sporoblasts were engulfed by valvogenic cells before they began to differentiate; whereas other sporoblasts consisted of six cells attached to each other, two being capsulogenic cells containing external tubes, two sporoplasmic cells and two valvogenic cells. There was a septate junction around the opening of the rounded polar capsule of the spore, between the capsulogenic and valvogenic cell. Sporoplasmosomes appeared to form in smooth membraned vesicles, possibly part of the Golgi apparatus. Spores had thin, delicate membrane, and elongate shell-valves, most of which were asymmetric, and bent or folded. A sporoplasm extended on either side of the distinct, straight suture line, but did not penetrate into the valves.

Animals↗
PubMed1994

Initial experience with a electronic CT image transfer system.

An electronic image transfer system for computed tomographic images links the CT scanner in Altnagelvin Hospital, Londonderry with the regional neuroradiology department in the Royal Victoria Hospital, Belfast. In the first 13 months of operation, scans of 100 patients were transferred; 49 scans were taken in acute neurosurgical emergencies, and 51 were non-acute sent for a specialist neuroradiological opinion. Potentially hazardous inter-hospital transfer was avoided in 21 cases of acute neurosurgical emergency, and more efficient and appropriate referral was achieved in the cases whose scans had been sent for sent for radiological second opinion. We believe that the system has substantially improved the diagnosis and management of patients with neurosurgical problems in both hospitals.

Adolescent↗
PubMed1992

Opioid modulation of thermal dehydration-induced thirst in rats.

Male Sprague-Dawley rats were utilized to study the effects of the opioid receptor antagonists, naloxone and naltrexone, on thirst induced by thermal dehydration. In an initial experiment, the depressant effect of naloxone (1.0 mg/kg, IP) on the water intake of rats deprived of water for 24 h was confirmed. In subsequent experiments, rats were thermally dehydrated by exposing them without water to a 40 degrees C environment for 1-4 h. Following heat exposure, rats were injected with either naloxone or naltrexone either IP or ICV. Fifteen minutes later, rats were provided with water and water intake was measured for 2 h. Both naloxone and naltrexone had dose (0.1-5.0 mg/kg, IP)-dependent effects of reducing water intake of rats thermally dehydrated for 3 h. Water intake of rats thermally dehydrated for 2 or 4 h was also attenuated by pretreatment with naloxone. Rats thermally dehydrated for 3 h exhibited decreases in water intake following ICV injection of either naloxone or naltrexone at a dose of 50 micrograms. Neither naloxone nor naltrexone had an effect on urine output in any experiment. The water intake data support the hypothesis that thirst induced by thermal dehydration in rats is modulated by an opioid mechanism.

Animals↗
PubMed1992

Age of acquisition, not word frequency, affects object naming, not object recognition.

Word frequency is widely believed to affect object naming speed, despite several studies in which it has been reported that frequency effects may be redundant upon age of acquisition. We report, first, a reanalysis of data from the study by Oldfield and Wingfield (1965), which is standardly cited as evidence for a word frequency effect in object naming; then we report two new experiments. The reanalysis of Oldfield and Wingfield shows that age of acquisition is the major determinant of naming speed, and that frequency plays no independent role when its correlation with other variables is taken into account. In Experiment 1, age of acquisition and phoneme length proved to be the primary determinants of object naming speed. Frequency, prototypicality, and imageability had no independent effect. In Experiment 2, subjects classified objects into two semantic categories (natural or man-made). Prototypicality and semantic category were the only variables to have a significant effect on reaction time, with no effect of age of acquisition, frequency, imageability, or word length. We conclude that age of acquisition, not word frequency, affects the retrieval and/or execution of object names, not the process of object recognition. The locus of this effect is discussed, along with the possibility that words learned in early childhood may be more resistant to the effects of brain injury in at least some adult aphasics than words learned somewhat later.

Adult↗
PubMed1989

Structural and functional analysis of nitrogenase genes from the broad-host-range Rhizobium strain ANU240.

The genes encoding the structural components of nitrogenase, nifH, nifD and nifK, from the fast-growing, broad-host-range Rhizobium strain ANU240 have been identified and characterized. They are duplicated and linked in an operon nifHDK in both copies. Sequence analysis of the nifH gene from each copy, together with partial sequence analysis of the nifD and nifK genes, and restriction endonuclease analysis suggested that the duplication is precise. Comparison of the Fe-protein sequence from strain ANU240 with that from other nitrogen-fixing organisms revealed that, despite its broad host range and certain physiological properties characteristic of Bradyrhizobium strains, ANU240 is more closely related to the narrow-host-range Rhizobium strains than to the broad-host-range Bradyrhizobium strains. The promoter regions of both copies of the nif genes contain the consensus sequence characteristic of nif promoters, and functional analysis of the two promoters suggested that both nif operons are transcribed in nodules.

Amino Acid Sequence↗
PubMed1987

Collecting cancer registry data with a Cancer Patient Questionnaire.

Tumor registries provide a valuable source of treatment, survival, and epidemiologic data but have been faulted for incomplete and insufficient collection of data. An eight page, 38-item Cancer Patient Questionnaire (CPQ) was developed to collect more extensive information for the tumor registry. The CPQ identified significantly more patients with a family history of cancer than had previously been detected by chart review by the tumor registrar. The CPQ agreed with data collected by the tumor registry in 96% of cases for place of birth, 84% of cases for occupational history, 91% of cases for tobacco use, and 88% of cases for number of pregnancies or live births. The Cancer Patient Questionnaire is complete and easy to use and may replace the chart review in the collection of these data.

Data Collection↗
PubMed1978

The fine structure of the ventricular surface of the area postrema of the cat, with particular reference to supraependymal structures.

The ependymal surface of the feline area postrema (AP) has been examined with the scanning and transmission electron microscopes. Particular attention was paid to the distribution and structure of supraependymal (SE) cells which have not been described before on this organ. A population of SE cells was found consistently on the cat AP; they were grouped most frequently toward the caudal aspect of the organ. Their structure bears a great resemblance to that of macrophages, containing: (1) many small apical vacuoles, (2) numerous lysosomes, and (3) phagosome-like bodies. Arrays of microvillous tufts and also singly-occurring microvilli are features of the unciliated ependymal surface of the organ. Tufts are often found in very close proximity to superficial blood vessels which are characteristically surrounded by large perivascular spaces.

Animals↗
PubMedDate not supplied

Morphology of diplomonad flagellates: Spironucleus torosa n. sp. from Atlantic cod Gadus morhua L., and haddock Melanogrammus aeglefinus (L.) and Hexamita salmonis Moore from brook trout Salvelinus fontinalis (Mitchill).

A diplomonad flagellate, Spironucleus torosa n. sp. is described from Atlantic Cod Gadus morhua and haddock Melanogrammus aeglefinus. This is believed to be the 1st confirmed report of Spironucleus from a marine fish. Organisms swimming in the rectal lumen were broadly pyriform to elongate, and measured 10.5-18.6 microns long and 3.2-13.3 microns wide; other elongate organisms were attached to the rectal epithelium, via apical extensions appearing continuous with the microvilli. The posterior end of the body was extended into a caudal projection, on either side of which was a posteriolateral ring-shaped protrusion or torus, with a recurrent flagellum emerging from its centre. A symmetrical system of microtubules and lamellae, forming a "V" in protargol impregnated specimens, supported the flanges of the body surrounding the tori, the tori themselves and the caudal projection. Supranuclear microtubules were an inverted V to U shape in transverse section, and an electron dense band accompanied the cytostomes. Lightly staining homogenous cytoplasm was usually present in the anterior part of the body, the remainder being highly vacuolated with numerous dark granules. In swimming organisms, rough endoplasmic reticulum (RER) was present around the nuclei and cytostomes, and bacteria were occasionally seen in the cytoplasm. In "attached" organisms, RER was reduced, and bacteria were absent. Hexamita salmonis Moore from Salvelinus fontinalis was studied by light and scanning electron microscopy for comparison; its cytoplasm was not highly vacuolated. The two recurrent flagella emerged close together from the blunt posterior end of the body.

Animals↗