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Biomedical subjects

A Lee

Publications and source records attributed to A Lee.

At least 775 records · Page 43Linked to original sources
PubMed1978

The mucosa-associated microflora of the rat intestine: a study of normal distribution and magnesium sulphate induced diarrhoea.

Specimens of intestinal mucosa of rats were examined closely to determine the distribution of the mucosa-associated microbial flora. Six distinct zones were found along the length of the intestinal tract. The first zone, in the small intestine 50 cm or more from the ileocaecal junction, had no associated flora: however, each of the five other zones had different populations of microorganisms associated with the mucosa. Some of these organisms have not been reposted previously. Treatment of rats with oral doses of the purgative magnesium sulphate resulted in dramatic changes in the distribution of these mucosa-associated microorganisms. The normal flora of ileal and caecal crypts disappeared, while the organisms in colonic crypts were unchanged. Large numbers of mucosa-associated bacteria appeared in the stools of treated animals.

Animals↗
PubMed1978

The effect of 5-fluorouracil on abdominal wound healing in rats.

We carried out experiments to test the hypothesis that 5-Fluorouracil would retard wound healing when administration was started on the day of operation. Abdominal wounds were made in rats and closed again, and some of the animals were given daily 5-FU, the rest acting as controls. Test animals were killed three, five, seven and 10 days after operation, and the strength of their wounds was measured. At five and seven days the control wounds were 10 times stronger than those of the treated animals, and at 10 days they were four times stronger. We speculated that the difference in strength might be largely due to the observed fact that the muscle layer in the treated animals was considerably weaker than in the controls. We concluded that it would be unsafe to start giving 5-FU to patients immediately after operation.

Abdominal Muscles↗
PubMed1978

Field independence and performance on ball-handling tasks.

Subjects were administered the Children's Embedded Figures Test and four ball-handling tests. Pearson product-moment correlations were low between the measures. Girls scored significantly higher than boys on the embedded figures test while boys scored significantly higher than girls on the striking and throwing tests.

Child↗
PubMed1977

Interaction of glucocorticoid hormones and cyclic nucleotides in induction of tyrosine aminotransferase in cultured hepatoma cells.

Reproducible induction of the enzyme tyrosine aminotransferase by dibutyryl cAMP (Bt2cAMP) in a line of HTC hepatoma cells in suspension culture requires that the cells be preinduced with dexamethasone, a synthetic glucocorticoid which itself induces tyrosine aminotransferase. Concentrations of dexamethasone that do not induce tyrosine aminotransferase fail to support Bt2cAMP induction, removal of the steroid from the medium leads to a loss of the Bt2cAMP effect, and an HTC cell line whose aminotransferase is not steroid-inducible does not respond to the cyclic nucleotide. We show that the further induction of tyrosine aminotransferase by Bt2cAMP in dexamethasone-treated cells is due to an increased rate of enzyme synthesis. The cyclic nucleotide has no effect on aminotransferase synthesis in cells grown in the absence of steroid. Several lines of evidence suggest that dexamethasone acts at a step beyond the activation of protein kinase by cAMP: (a) basal levels of cAMP are not altered by growth of HTC cells in dexamethasone; (b) accumulation of cAMP from the medium is not enhanced; (c) the glucocorticoid does not induce cAMP-dependent protein kinase in HTC cells; and (d) there is no augmentation of cAMP binding to the regulatory protein, nor is there any change in cAMP activation of protein kinase caused by growth in dexamethasone. These results help define a system that should be useful in studying the interaction of cyclic nucleotides and steroid hormones.

Bucladesine↗
PubMed1977

American Burkitt's lymphoma in Pittsburgh, Pennsylvania.

A confirmed case of American Burkitt's lymphoma with jaw involvement in a 12-year-old Caucasian girl from western Pennsylvania is described. There were clinical manifestations in the mandibular quadrants and radiographic manifestations in all mandibular and maxillary quadrants. One of the earliest clinical manifestations of the lymphoma in the mandible was observed by a family dentist. The lymphoma later produced a deterioration of the overlying mandibular mucosa, moderate expansion of the cortex of the mandible, and paresthesia of the lip with probable V3 involvement. Four months after the first admission there were radiographic manifestations of the lymphoma in both the maxillary and mandibular quadrants. Early diagnosis and appropriate management may improve the prognosis.

Burkitt Lymphoma↗
PubMed1977

The role of preliminary magazine training in acquisition of the autoshaped key peck.

A series of experiments tested the hypothesis that initial key pecks in the autoshaping procedure are generalized pecks at the illuminated grain hopper. Experiment I found that autoshaping readily occurred when the chamber was continuously illuminated by a house-light. In Experiment II, pigeons given magazine training and autoshaping with an unlighted grain hopper failed to autoshape in 200 trials. Acquisition of autoshaped key pecking was retarded in Experiment III when stimulus control by the magazine light was reduced. In the fourth study, pigeons were given magazine training with either a red or white magazine light and then given autoshaping with concurrently presented red and white keys. For all pigeons in this experiment, the first key peck occurred on the key of the same color as that pigeon's magazine light. The results of these experiments were interpreted as supporting an account of autoshaping that identifies initial key pecks as arising due to generalization of pecking at the lighted grain hopper to pecking at the lighted key.

Journal Article↗
PubMed1976

Vibrio cholerae infection and immunity in mice.

Lyophilized cultures of V. cholerae 569B slowly lose their virulence for neonatal and adult mice during long term storage. Following a single passage in orally infected 6-day old mice, a highly virulent strain (designated 569B/MP) was isolated. This organism causes rapidly fatal intestinal infections in 6-day old mice; large numbers can be isolated in pure culture from the intestinal fluid. Freezing and storage at -60 degrees of dead animal provides a simple means of maintaining the high virulence of the culture over a period of at least 9 months. This strain produces choleracic symptoms and death in approx. 50% of adult mice following oral infection. Large numbers of viable organisms may also be isolated from the small intestine over a period of at least 40 h. These criteria have been used as a basis for assessing protection against cholera infection induced by immunization with living or heat-killed V. cholerae given orally or intraperitoneally.

Animals↗
PubMed1976

Acquisition of the autoshaped key peck as a function of amount of preliminary magazine training.

Three experiments evaluated the effect of magazine training on acquisition of the pigeon's key peck during autoshaping. In Experiment I, pigeons were exposed to two days of extended magazine training, followed on the third day by keylight-only presentations. All pigeons pecked the keylight early in the keylight-only session. Experiment II examined the relationship between the number of magazine-training trials and trials to the first peck. Pigeons were given either 0, 3, 10, or 25 magazine-training trials followed by the standard autoshaping procedure. The number of trials to the first peck was related to the number of magazine-training trials. In Experiment III, pigeons were exposed to the standard autoshaping procedure without prior magazine training. The data from Experiment III suggested that key pecking will occur only after the response of eating from the lighted hopper has occurred. Taken together, these results suggest that initial magazine training is an important variable in autoshaping. Key pecking is discussed as a generalized consummatory response.

Journal Article↗