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Biomedical subjects

G Nicholson

Publications and source records attributed to G Nicholson.

At least 91 records · Page 5Linked to original sources
PubMed1986

Campylobacter pyloridis infection in Auckland patients with gastritis.

A prospective study of 53 patients was undertaken to determine the presence of Campylobacter pyloridis infection in patients undergoing endoscopy at Auckland Hospital. Twenty-four patients (47%) were infected with C pyloridis. Twenty-three of the 28 patients with active chronic gastritis and one of the seven patients with chronic gastritis were infected. None of the 17 patients with normal antral histology were infected. Infection was significantly correlated with active chronic gastritis (p less than 0.001). Infection was not associated with any particular symptom complex or endoscopic finding.

Adult↗
PubMed1986

Synergistic effect of coumadin and cytoxan in reducing lung metastases.

Lung metastasis is a frequent cancer complication resulting in significant mortality. This study evaluates the effect of coumadin and cytoxan alone and in combination on lung metastases in rats challenged with Morris hepatoma 3924A. Seventy-seven male American Cancer Institute (ACI) rats weighing 200 g were studied. Thirty-seven rats received coumadin orally for six days, which resulted in a prothrombin time 2 times that of controls (30 sec). All rats received 1 X 10(5) clumped Morris hepatoma cells via tail vein injection. Animals were divided into four groups: Group I (controls, n = 20) received no antitumor treatment; group II rats (n = 20) received 25 mg/kg cytoxan intraperitoneally at the time of tumor challenge; group III animals (n = 19) received coumadin alone; while group IV (n = 18) received both coumadin and cytoxan. Rats were evaluated for number of lung metastases and lung weight at 3 weeks postinjection. Data was subjected to statistical analysis by the Student's test. The mean number of lung metastases were 580 +/- 45 in group I, 350 +/- 310 in group II, 330 +/- 263 in group III, and 200 +/- 161 in group IV (P less than .005 [IV] v [I], P less than .05 [IV] v [II], [III]), (P less than .05 [II] v [I]), (P less than .05 [III] v [I]). Mean lung weights were 2.597 g +/- 1.65 in group I, 2.049 g +/- 0.75 in group II, 1.898 g +/- 0.80 in group III, and 1,677 g +/- 0.31 in group IV. (P less than .025 [IV] v [I], P less than .05 [IV] v [II]).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Patient immobilization during CT for treatment planning of head and neck cancer.

Immobilizers are described that have been used during computed tomography (CT) to ensure reproducibility of patient position during all phases of radiation treatment planning and delivery. The immobilizer causes no degradation or artifact on CT images; hence, the value of the images in radiation treatment planning is not compromised.

Head and Neck Neoplasms↗
PubMed1985

Tripotassium dicitrato-bismuthate tablets v liquid in the treatment of duodenal ulcers.

Thirty-five patients with duodenal ulcers were treated with tripotassium dicitrato-bismuthate (TDB) in a double-blind, double-dummy endoscopically controlled trial. Healing rates were comparable in patients treated with either tablet or liquid, 74% and 72% at four weeks and 89% in both groups at eight weeks. It is concluded that the tablet formulation of TDB is as effective as the liquid in the treatment of acute duodenal ulceration.

Adult↗
PubMed1983

Effect of immediate student evaluations on a multi-instructor course.

Immediate student feedback and peer evaluation by a single physician were used to evaluate and monitor an interdisciplinary multi-instructor course. Clinical Correlations with Pathology is taught during the second year of medical school by 50 instructors, each of whom has a limited exposure to sophomore medical students. The format of the course, in which the same students evaluate multiple lecturers in multiple content areas, provided a unique opportunity to demonstrate the reliability and validity of student evaluations. About one-half of the lectures were repeated by the same instructors the following year to the next class of medical students, who also evaluated all of the lectures. Comparison of two consecutive sophomore classes of medical students documented overall course improvement and showed higher ratings given to instructors who presented the same lecture both years. Student evaluation is a powerful technique that can result in positive changes leading toward course improvement.

Education, Medical↗
PubMed1980

Studies of the neural mechanisms by which hypothyroidism decreases prolactin secretion in the rat.

These studies report that chronic hypothyroidism in the rat is accompanied by decreased serum prolactin. An investigation of those mechanisms by which hypothyroidism decreases prolactin secretion revealed the following findings: (1) activation of tyrosine hydroxylase in the median eminence (ME) and increase in the turnover-rate of dopamine (DA) in the ME; (2) a decreased content and in vitro release of prolactin by pituitaries from hypothyroid rats; (3) decreased [3H]spiroperidol binding to pituitary homogenates obtained from hypothyroid rats, and (4) normal increase of serum prolactin following administration of haloperidol. Comparison of the effects of hypothyroidism on dopaminergic terminals of the striatum with those of the ME was made and the following tentative conclusions proposed. Hypothyroidism presumably increases the release of DA into the pituitary portal system. A deficiency of thyroid hormone desensitizes the pituitary lactrotrope to inhibition by DA, decreases the total pituitary prolactin content and presumable also reduces the peripheral catabolism of prolactin. The overall net effect of hypothyroidism is, therefore, a decrease in serum prolactin levels which can increase normally following haloperidol. The mechanism by which a deficiency of thyroid hormone alters the function of the tuberoinfundibular and striatal dopaminergic systems is unknown.

Animals↗
PubMed1980

Prolactin in cerebrospinal fluid: a probable site of prolactin autoregulation.

The purpose of this study was to examine the thesis that increasing concentrations of prolactin within the cerebrospinal fluid (CSF) increase the activity of dopaminergic terminals within the median eminence and that this increased dopaminergic activity is temporally associated with a suppression of endogenous prolactin secretion. To avoid difficulties encountered in performing catecholamine turnovers in the undisturbed rat, the measurement of tyrosine hydroxylase was validated as an index of dopaminergic activity within the median eminence. In the median eminence, but not the medial preoptic area, parallel increases in the activity of tyrosine hydroxylase and the turnover of dopamine (but not norepinephrine) occurred following hyperprolactinemia. Twenty-six hours but not 2.5 h after the subcutaneous administration of ovine prolactin, the activity of tyrosine hydroxylase was increased in the median eminence, and endogenous prolactin secretion was inhibited. During a 26 h continuous intracerebroventricular (icv) infusion (88 ng/h) of rat prolactin, there was a complete suppression of endogenous prolactin secretion. Twenty-six but not 2.5 h after the initiation of the icv infusion of prolactin, there was an increase in tyrosine hydroxylase activity in the median eminence. The results of these studies suggest that: (1) measurement of tyrosine hydroxylase activity within the median eminence is a useful index of the activity of dopaminergic terminals; (2) increasing concentrations of prolactin within the CSF suppressed prolactin secretion by the anterior pituitary; (3) this suppression of prolactin is accompanied by an increased activity of dopaminergic terminals within the median eminence; (4) those neural structures concerned with the regulation of prolactin secretion respond directly to prolactin itself; (5) the autoregulation by prolactin of its own secretion manifests a certain latency more characteristic of a tonic rather than a phasic inhibitory control; and finally, (6) dopaminergic terminals in the median eminence but not the preoptic area appear uniquely sensitive to prolactin.

Animals↗
PubMed1980

Neonatal monosodium glutamate. Effects upon analgesic responsivity and immunocytochemical ACTH/beta-lipotropin.

Neonatal administration of monosodium glutamate (MSG) produces neurotoxic degeneration of the retina and medial-basal hypothalamus, including the arcuate nucleus. Since this hypothalamic area contains the only neuronal cell bodies in brain which contain adrenocorticotrophic hormone (ACTH) and beta-lipotropin (beta-LPH) and beta-endorphin, destruction of these cells by MSG may interfere with pain responses mediated by nerve fibers arising from these perikarya. The present study examined whether MSG-treated rats, as compared to littermate controls, exhibited concomitant changes in the immunocytochemical distribution of ACTH and beta-LPH, and their reactivity to several analgesia-inducing manipulations. Although MSG-treated rats did not differ from control rats in their baseline reactivity to electric shock, they displayed an inability to exhibit analgesia following acute exposure to cold-water swim stress. In addition, MSG-treated rats showed an attenuated analgesic response following morphine administration. However, the analgesia elicited by either abrupt food deprivation, or the glucoprivic stress of 2-deoxy-D-glucose, was unaffected by neonatal MSG treatment. Concomitant with these selective analgesic deficits, MSG-treated rats displayed a marked immunocytochemical reduction in ACTH/beta-LPH perikarya and terminals in brain, but not pituitary. These data indicate that multiple pain-inhibitory systems exist, and that some rely upon an intact medial-basal hypothalamus to produce analgesia.

Adrenocorticotropic Hormone↗
PubMed1980

Incidence of hepatitis B-antigenaemia and positive alphafoetoprotein in New Zealand, Western Samoa and Tonga--(a pilot study of Polynesian liver disease).

A pilot study was carried out to determine the nature of Polynesian liver disease by a study of blood donors and liver biopsy material from natives in Samoa, Tonga and Auckland, New Zealand. The data is suggestive that the Hepatitis B carrier state and hepatoma are greater in Polynesians than in Europeans. One familial hepatoma in two Maori brothers at ages of 11 and 13 years are reported.

Adolescent↗
PubMed1979

The ionic components of normal human oesophageal epithelium.

The distribution of cations and anions in normal human oesophageal epithelium has been investigated with the pyroantimonate and silver-osmium tetroxide techniques. There is a discontinuous distribution of both ions in the intercellular space. The ions are associated with various organelles, as has already been described in the literature. Specifically, in the oesophageal epithelium, there are a few deposits of pyroantimonate and occasional silver in the membrane coating granules, but here is no apparent relationship of either ion with the tonofilaments or glycogen particles. The superficial cells are leaky and contain fewer ions than the deeper functional layer cells.

Anions↗
PubMed1979

The distribution and mobility of surface anionic groups of normal human oesophageal epithelium following interaction with cationized verritin.

Oesophageal epithelial cells from biopsies from normal patients showed the presence of randomly distributed anionic groups, mostly sialic acid on the cell membrane in fixed material shown by cationized ferritin. When biopsies were pulse labelled, patching occurred in all three cell layers. Patching was energy dependent and did not occur at 4 degrees C. Pulse labelled material incubated on an unlabelled medium showed progressive loss of cationized ferritin from the cell membrane. This was mostly into the medium, although some was internalized in membrane profiles. A second pulse of cationized ferritin produced further patching suggesting regeneration of cell membrane. Superficial cells were leaky, but their organelles were not.

Anions↗
PubMed1979

Changes in enzyme activity in normal and histologically inflamed oesophageal epithelium.

Oesophageal biopsies were obtained from 74 patinets undergoing upper gastrointestinal fibreoptic endoscopy. Thirteen patients with histological evidence of inflammation had a raised alkaline phosphatase activity (2.7 +/- 1.6 nmol/mg protein/min) compared with 49 normal controls (1.2 +/- 0.68 nmol/mg protein/min: P less than 0.001). The acid phosphatase level was lower (8.4+/- 4.0 vs. 5.8 +/- 2.2 nmol/mg protein/min: P less than 0.05) and the glucuronidase activity raised (0.44 +/- 0.17 vs 0.81 +/- 0.32 nmol/mg protein/min: P less than 0.001) and their ratio declined (24.0 +/- 1.9 nmol/mg protein/min: P less than 0.001) in patients with oesophagitis. This may be due to differential secretion of membrane coating granules, a form of lysosome found isophagitis--was assessed by point counting. The volume density rose from 10.9 +/- 4.25% in normal biopsies to 46.4+/-12.5% (P less than 0.001) in oesophagitis. These results show a consistent pattern that possibly indicates an intermediate stage between the clinically, histologically, and biochemically normal oesophagus and one that is inflamed on endoscopy.

Acid Phosphatase↗
PubMed1978

The effect of castration, thyroidectomy and haloperidol upon the turnover rates of dopamine and norepinephrine and the kinetic properties of tyrosine hydroxylase in discrete hypothalamic nuclei of the male rat.

Adult male rats were either castrated, thyroidectomized, or treated with haloperidol and the rates of turnover of dopamine (DA) and norepinephrine (NE) in the median eminence (ME), the arcuate and dorsomedial nuclei of the hypothalamus were estimated from the rate of decay of DA and NE concentrations as determined by radioenzymatic assay following blockade of catecholamine synthesis by alpha-methyl-p-tyrosine. The ME of animals similarly prepared was also examined for changes in the total activity and kinetic properties of tyrosine hydroxylase (TH). Four days following the administration of haloperidol (400 microgram/kg) or 10 days after castration, there was a significant increase in the rate of turnover of DA but not NE in the ME accompanied by an increase in the Vmax but not Km for the substrate or cofactor of TH. Furthermore, the administration of haloperidol to hypophysectomized rats also significantly increased the TH activity in the ME, indicating that such changes may occur independently of any changes in serum prolactin levels. Ten days after thyroidectomy, or three weeks after treatment with prophylthiouracil, there was a significant increase in the turnover rate of DA in both the ME and dorsomedial nucleus but not in the arcuate nucleus. No changes in the turnover rates of NE in any of the three areas were observed following thyroidectomy. In the ME, the increase in turnover of DA was accompanied by an increase in the total TH activity (Vmax) as welll as a decrease in Km for tetrahydrobiopterin but not tyrosine. From these results 4 conclusions were drawn: (1) following halperidol, castration, and thyroidectomy there are increases in the activity of dopaminergic terminals within the ME; (2) castration, haloperidol and thyroidectomy may influence the activity of dopaminergic terminals within the ME by different mechanisms; (3) changes in tyrosine hydroxylase and turnover of catecholamines within the ME may occur independently of changes in prolactin levels; and (4) local recurrent afferent circuits may exist in the arcuate nucleus region of the hypothalamus.

Animals↗