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Biomedical subjects

R J Stewart

Publications and source records attributed to R J Stewart.

At least 109 records · Page 6Linked to original sources
PubMed1985

Differential effects of intrafrontocortical microinjections of dopamine agonists and antagonists on circling behavior of rats.

Asymmetric posturing and circling behavior resulting from acute unilateral manipulation of central dopamine have been used to assess this neurotransmitter's contribution to motor control. Although providing extensive evidence for the involvement of mesolimbic and nigrostriatal dopamine in motor activity, this approach has not been used to study the mesocortical system. We now report circling behaviour following acute manipulation of frontal cortical dopamine. Unilateral microinjections of the agonists, (+)-amphetamine (12 and 25 micrograms in 1.0 microliter) and LY 141865 (12 micrograms in 1.0 microliter) resulted in contraversive circling. Conversely, unilateral intrafrontocortical microinjections of the antagonist, metoclopramide (25 and 100 micrograms in 1.0 microliter) resulted in ipsiversive circling in amphetamine (1.5 mg/kg, i.p.) pretreated rats. Lower central doses of each drug and vehicle injections had no significant effect. These results provide evidence for an excitatory influence of mesocortical dopamine on motor control. This finding may implicate frontal cortical dopamine in the extrapyramidal motoric side effects of chronic neuroleptic treatment which previously have been attributed to dopamine function in subcortical areas.

Animals↗
PubMed1985

Effects of unilateral microinjections of sulpiride into the medial prefrontal cortex on circling behavior of rats.

Bilateral 6-OHDA lesions of rats' medial prefrontal cortex increased locomotor activity after 7-10 days suggesting that cortical DA may normally inhibit motor behaviour. However, hyperactivity may have resulted from enhanced subcortical DA function. Acute manipulation of frontal cortical DA neurotransmission in the present experiment avoided lesion-induced subcortical changes. Sulpiride (0, 6, 12, 24 micrograms in 1 microliter) was injected unilaterally into the medial prefrontal cortex of rats pretreated with (+)-amphetamine (1.5 mg/kg, i.p.). Circling behavior was scored during four 5-min intervals of a 60-min test session which began with injections and placement in a flat, circular arena. SUL resulted in ipsiversive circling whereas its vehicle did not. These results were consistent with those seen with other DA drugs and suggest an excitatory influence of frontal cortical DA on locomotor activity.

Animals↗
PubMed1985

Density estimation and population growth of mosquitofish (Gambusia affinis) in rice fields.

Mark-release-recapture estimation of population density was performed with mosquitofish in a rice field habitat. Regression analysis showed a relationship between absolute density and mean number of fish per trap. Trap counts were converted to density estimates with data from several fields and growth curves were calculated to describe seasonal growth of mosquitofish populations at three different initial stocking rates. The calculated curves showed a good correspondence to field populations of mosquitofish.

Animals↗
PubMed1984

Changes in the pattern of disease managed by general surgeons in New Zealand, 1940-80.

Changes in the pattern of disease managed by general surgeons in New Zealand, were assessed for the period 1940-80, using the public hospital admission and cancer incidence data of a representative selection of diseases. During the forty-year period, there was an increase in the incidence of four of the five cancers studied, and an increase in admission rate for non-specific abdominal pain, head injury (indicated by skull fracture), peripheral arterial disease (indicated by aortic aneurysm), gall-stone disease and pancreatitis, large bowel disorders and breast diseases. There was a decline in admission rate for appendicitis, stomach disorders and goitre.

Abdomen↗
PubMed1984

Meta-iodobenzylguanidine in metastatic phaeochromocytoma.

A case of metastatic phaeochromocytoma is presented. Meta-iodobenzylguanidine was used to locate the tumour but failed to show two functioning abdominal metastatic deposits. Although meta-iodobenzylguanidine appears to be highly specific for phaeochromocytoma, a negative scan does not exclude a functioning tumour with confidence.

3-Iodobenzylguanidine↗
PubMed1984

Peritoneal neutrophilia: a potential indicator of the surgical acute abdomen.

The percentage of neutrophils in a peritoneal cell sample (PNP), obtained at operation, was measured in 250 patients who underwent urgent laparotomy because 'the surgical acute abdomen' (SAA) was suspected. The PNP was substantially higher in patients with confirmed SAA than in others and is potentially a very sensitive and very specific test of SAA. If the PNP was available as a diagnostic test for patients with acute abdominal pain, there might be a significant reduction in unnecessary and delayed laparotomies.

Abdomen, Acute↗
PubMed1983

Sex differences in subsite incidence of large-bowel cancer.

A review of patients with large-bowel cancer at a major New Zealand hospital showed an excess of right-sided colonic tumors in females compared with males. These observations stimulated analysis of the National Cancer Registry registration data for large-bowel cancer for the whole of New Zealand in the years 1972 to 1975 (4678 patients). Rates for each site were calculated and age-standardized, using world population figures. The findings confirmed that females have a higher incidence of right-sided colonic cancer and males a higher incidence of rectal cancer and showed a significant trend in this direction from the ascending colon toward the rectum. The observed differences between males and females suggest differences in the etiology of the tumor and should be taken into account in assessing modalities and outcomes of treatment.

Colonic Neoplasms↗
PubMed1982

Cancer of the stomach in New Zealand: 1970-74.

A total of 1,891 new cases of cancer of the stomach occurred in New Zealand (1971 population 2,862,631) in the five years 1970-74. There was a higher incidence in men than women and in Maoris compared to Europeans. The disease had declined in incidence by about 50% in 20 years. Most of the cancers occurred in the distal stomach and were described as adenocarcinomas. Seventy percent of the patients had a lymph node metastases or advanced disease at the time of diagnosis. Only 39% were able to have resectional surgery and in 57% specific therapy was not given. The estimated crude five year survival rate of all patients was 7.8% (relative rate 10.2%) and the crude five year survival rate after resectional surgery was 18.7% (relative rate 24.7%). The most important variables affecting survival were the stage of the disease and the age of the patient.

Age Factors↗
PubMed1982

Cancer of the pancreas in New Zealand 1970-1974.

There were 991 new cases of cancer of the exocrine pancreas in the New Zealand population for the five years 1970-74. The disease had a higher incidence in men than women and in Maoris compared to Europeans. There was no increase in incidence in the period 1950-52 to 1971-73. Most of the cancers occurred in the head of the pancreas and were described as adenocarcinomas. Seventy seven per cent of the patients had lymph node metastases or advanced disease at the time of diagnosis. Only 7 per cent were able to have resectional surgery and in 90% specific therapy was not given. The estimated crude three-year survival rate of all patients was four per cent and the median survival time was 1.7 months. The crude three year survival rate after resection was 9.8% and the median survival time was 5.8 months. The most important variables affecting survival were stage of disease and age of patient.

Adenocarcinoma↗
PubMed1981

The wound fibroblast and macrophage. I: Wound cell population changes observed in tissue culture.

The number and type of cells which migrated from sequential explants of wounded fascia in rats reflected the dense and changing cell populations observed in healing wounds. Macrophages appeared in large numbers from explants taken in the 5 days following injury, thereafter fibroblast-like cells predominated. The results support the hypothesis that the fibroblast-like cell of tissue culture is the same as the wound fibroblast. The technique can be used to obtain wound cells and provides a useful bridge between in vivo and in vitro means of investigating wound repair.

Animals↗
PubMed1981

The wound fibroblast and macrophage. II: Their origin studied in a human after bone marrow transplantation.

The origin of the wound fibroblast and macrophage was studied in a patient following bone marrow transplantation, using sex chromosome markers. Fibroblast-like cells emigrating from explants of a 5-day-old skin wound had the host karyotype, whereas macrophages had donor markers. These results suggest that the wound fibroblast in man is of local tissue origin, whereas wound macrophages are derived from haemopoietic tissue.

Bone Marrow Transplantation↗
PubMed1980

The effect of rehabilitation at different stages of development of rats marginally malnourished for ten to twelve generations.

1. Rats which have been maintained for ten to twelve generations on diets of low protein value were rehabilitated in utero (group P), from birth (group F) and from 4 weeks of age (group W). 2. Group W showed little change in physique, behaviour or learning, indicating that for recovery to be effective refeeding must begin earlier. 3. Group F just failed to attain full physical recovery (90%) whereas group P overgrew by 18.6% in weight and 8.5% in length. 4. In a test designed to evaluate learning ability rehabilitated rats of groups P and F were significantly less successful than normal rats, but more successful than rats of group W or rats of the original undernourished colony. 5. Rehabilitation for a further two generations in groups F and P corrected any residual physical and behavioural defects but produced no further improvement on the Lashley (1938) jumping platform.

Acoustic Stimulation↗