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Biomedical subjects

N S Track

Publications and source records attributed to N S Track.

At least 55 records · Page 3Linked to original sources
PubMed1978

The antral gastrin-producing G-cell: biochemical and ultrastructural responses to feeding.

The effect of feeding on serum and antral immunoreactive gastrin (IRG) concentrations and on the ultrastructural appearance of antral G-cell granules has been examined. Serum and tissue IRG concentrations were dependent upon the length of time (12 or 48 h) the rats had been fasted before receiving food; IRG release was biphasic; the first peak was more pronounced in rats fasted 12 h. Antral tissue IRG content increased significantly postprandially. An initial depletion of antral IRG was seen in rats fasted 48 h. Examination of the subcellular distribution of antral IRG revealed more of the 5-15 min postprandal total IRG in the cytoplasm and less in the secretory granules. Ultrastructurally, G-cells from fasting rats contained mainly electron-dense granules. Five minutes postprandially numerous electron-lucent granules were observed. More electron dense granules were apparent 60 and 120 min postprandially. Fasting rats had the highest G-cell granule density index; a significantly lower index was observed 5 min postprandially. Indices at 60 and 120 min postprandially increased but were still lower than the fasting index. These studies indicate that gastrin biosynthesis is necessary for food stimulated gastrin release and that the electron density of the G-cells granules is not an accurate reflection of the G-cell gastrin content.

Animals↗
PubMed1978

Metabolic responses to enteral and parenteral nutrition.

Seven pairs of rats were simultaneously infused with a chemically formulated nutritionally complete amino acid-glucose diet which was delivered, at the same rate, into a central vein or into a feeding gastrostomy. The intragastrically infused rats showed greater weight gain than did the intravenously infused rats. This could not be explained by fluid retention since intake and output were similar in the two groups of animals. There was a greater increase in serum immunoreactive insulin (IRI) at day 8 in the intragastrically infused animals, but a smaller increment in serum immunoreactive pancreatic glucagon (IRG) at that point. Levels of enteroglucagon or glucagon-like immunoreactivity (GLI) were maintained in the intragastrically infused rats but declined markedly in the intravenously infused rats. It is possible that the greater release of IRI seen with the intragastric amino acid-glucose feeding contributes to better disposal of nutrients and greater weight gain. The presence of nutrients in the intestinal lumen may have stimulated the release of GLI, which in turn is insulinotropic.

Amino Acids↗
PubMed1978

Increased serum immunoreactive gastrin levels in idiopathic hypertrophic pyloric stenosis.

The serum immunoreactive gastrin (IRG) level in infants with confirmed idiopathic hypertrophic pyloric stenosis (IHPS) has been determined and compared to that found in vomiting infants without IHPS, in normal infants, and in normal adults. The mean serum IRG level of normal infants (103 +/- 9 pg/ml (mean +/- SEM) exceeded that of normal adults (28 +/- 5 pg/ml). The preoperative mean serum IRG level in IHPS infants (256 +/- 26 pg/ml) was significantly higher than that of both normal infants and vomiting infants without IHPS (93 +/- 9 pg/ml). Twenty-five per cent (5/20) of the IHPS infants had serum IRG levels within the upper range of normal infants. Fasting serum IRG levels in IHPS infants were not altered immediately by pyloromyotomy. The results from this study suggest a relationship between gastrin and idiopathic hypertrophic pyloric stenosis.

Adolescent↗
PubMed1976

Mucosal gastrin concentration, molecular forms of gastrin, number and ultrastructure of G-cells in patients with duodenal ulcer.

The mean antral immunoreactive gastrin (IRG) concentration of 38 duodenal ulcer (DU) patients was significantly higher (35-9+/-5-2 mug/g) than that of 21 controls (15-9+/-2-6 mug/g). Also the mean IRG concentration in the proximal duodenal mucosa of 15 DU patients (3-2+/-0-8 mug/g) was higher (but not significantly) than that of 10 controls (1-8+/-0-5 mug/g). The number of G-cells in the antral mucosa of 58 DU patients and in the duodenal mucosa of 29 DU patients was not larger than that of controls. The distribution of immunoreactivity in gastrin components has been investigated in the antral and duodenal mucosa of six DU patients and six controls. In the antral mucosa the mean percentage of G-17 was 93-3% in DU patients and 92-0% in controls. G-34 amounted to 4-0% in DU patients and to 5-0% in controls. The G-34 percentage in the duodenal mucosa was higher (however not significantly) in the DU patients than in the controls (50-1% versus 35-8%). Ultrastructurally, the antral G-cells of DU patients had a significantly lower density index of their secretory granules suggesting higher functional activity. It is concluded that the exaggerated serum IRG response of DU patients to different stimuli is not a consequence of an increased G-cell mass.

Adult↗
PubMed1976

Human insulinoma tissue: in vitro studies of proinsulin/insulin biosynthesis and release.

The rate of proinsulin/insulin turnover has been studied in human insulinoma tissue from ten patients. During the incubation of tumor tissue the ratio of immunoreactive insulin (IRI) release to content was significantly higher than that from isolated human pancreatic islets. The tumor cell cytoplasm (100,000 g supernatant S-100) contained approximately 45% of the IRI. Endogenous proinsulin and insulin were released throughout the incubation. Newly synthesized proinsulin was detected in the 15 min pulse microsomal, secretory granule, S-100 and media samples. These results suggest that defective hormonal storage and release mechanisms are operative in human insulinoma cells resulting in a higher turnover of proinsulin and insulin compared with pancreatic islet tissue.

Adenoma, Islet Cell↗
PubMed1976

Histochemistry, ultrastructure and hormone content of human insulinomas.

Forty human insulin-producing tumors were investigated with histochemical, immunohistological and ultrastructural methods and extracted for insulin and proinsulin. These studies resulted in the following findings: 1) A variable number of tumor cells contained only a few or often no beta granules. 2) The insulin concentration was lower and the proinsulin percentage higher in insulinoma cells compared with normal beta-cells. 3) According to the ultrastructural appearance of the secretory granules four types of insulinoma were established. 4) Insulinomas frequently contained cells with atypical secretory granules which were Grimelius silver-positive. Their similarity to the Type IV islet cell and to cells regularly found in gastrinomas, Verner-Morrison tumors and glucagonomas suggests that all endocrine pancreatic tumors originate from a common precursor cell. 5) The morphological and biochemical findings support the theory that uncontrolled hormone release and/or decreased storage capacity are responsible for fasting hyperinsulinism in insulinoma patients. 6) The severity of hypoglycemia symptoms and the result of stimulatory tests were not related to the size, the insulin concentration and the total insulin content of the tumor.

Adenoma, Islet Cell↗
PubMed1975

[Effect of selective proximal vagotomy with and without pyloroplasty upon basal and food stimulated serum immunoreactive gastrin in patients with duodenal ulcer. (author's transl)].

The effect of selective proximal vagotomy (SpV) with (12 cases) and without (5 cases) pyloroplasty upon basal and food stimulated serum immunoreactive gastrin (IRG) was studied in duodenal ulcer patients. Following SpV, fasting serum IRG increased in all subjects; the increase was more pronounced in subjects whose postoperative insulin tests were negative. Postoperatively, the mean integrated IRG output over 2 hrs in response to a meal was significantly higher than the preoperative mean value in the 17 patients. Pyloroplasty had no effect upon the IRG response following a test meal.

Duodenal Ulcer↗
PubMed1975

Pathomorphologic, biochemical, and diagnostic aspects of gastrinomas (Zollinger-Ellison syndrome).

The clinical symptomatology of the Zollinger-Ellison syndrome and the pathologic anatomy of gastrinomas are reviewed. Experience with 17 patients with the Zollinger-Ellison syndrome is presented with special reference to stimulation tests (secretin, glucagon, calcium infusion, test meal) and to localization and immunohistologic, ultrastructural, and biochemical findings in gastrinomas. Multiple hormone production by the tumors is frequent. The ultrastructure and the Sephadex G-50 gel filtration patterns of immunoreactive gastrin in sera and tumors are not uniform and are not related to localization of the tumors in the pancreas or duodenum or to the gastrin concentration. Hyperplasia of the pancreatic islets is a frequent finding in gastrinoma patients, suggesting that hypergastrinemia may stimulate islet growth.

Antigens, Neoplasm↗
PubMed1975

Arterial pressure in clinically apparent diabetics.

The relationship between arterial blood pressure and clinically apparent diabetes mellitus was examined by measuring blood pressure, under standardised conditions, in 735 ambulant diabetic patients attending St. Mary's and King's College Hospital, London. Other biometric, clinical and family data were also systematically collected. A large proportion of first degree relatives of the diabetics and a control group of first degree relatives of non-diabetics were also seen and examined; they were also tested for the presence of unsuspected diabetes. Blood pressure in diabetics was evaluated in two ways. Mean pressures (systolic and diastolic) were calculated by age and sex and compared with similar data from two British non-diabetic populations. In addition, age and sex adjusted blood pressure "scores" were derived for each of the diabetic propositi and for the relatives by calculating the degree to which their pressures deviated from the mean of a corresponding age/sex group of non-diabetics. These deviations were then made comparable by standardising them for the systematic change in variance with age and sex. Using both "raw pressures" and "adjusted scores" the influence of age, sex, obesity, arm girth, response to diagnosis and ethnic, obstetric and anamnestic features were examined. Analysis of the influence of various characteristics of the diabetic state on blood pressure was made; this included mode of presentation, known duration; insulin dose and degree of metabolic control. Finally the relationship of blood pressure levels to the long-term sequels of diabetes was analysed with special reference to renal disease, eye changes, neuropathy and arterial disease. No systematic difference between arterial blood pressure in diabetics and a suitable control population was detected. Younger patients, females more than males, tended to have somewhat higher mean diastolic pressures but these were balanced by rather lower mean pressures in older diabetics. There was evidence of raised pressure levels at the time of diagnosis of diabetes, particularly in older patients, which "settled" with time for reasons which were not clear. The relationship of arterial pressure with adiposity was comparable to that in non-diabetics. After allowance for age and sex, blood pressures and scores were not related to the mode of onset of the diabetes. In the youngest onset group, however, known duration of diabetes appeared to correlate positively with arterial pressure in excess of the effect of age. Insulin dose and metabolic characteristics of the diabetes showed little clear association with arterial pressure but, as expected, patients with evidence of renal disease had higher mean pressures. However, cause-effect relationship between raised pressure and renal disease in diabetics may operate in both directions. Some elements of retinopathy were positively correlated with blood pressure; others were not. The role of co-existing renal disease in determining this association was examined...

Adolescent↗