An intercomparison of whole-body counters at participating region III nuclear power plants.

Seventeen Region III nuclear stations originated and participated in an intercomparison study of their whole body counting procedures using the same calibration standard. The first phase of the study involved transporting a phantom containing four reactor-produced radionuclides and 40K to each plant. The plant staff were asked to follow all procedures applicable for a human subject including routine and investigative counts, if necessary, and to provide a printout of the results to the project investigators. The results from each plant were normalized for intercomparison by calculating the ratio of the reported activity to the actual activity after correcting for the appropriate amount of decay to the time of the count. Five plants reported 60Co values outside 1 standard deviation (SD) of the mean for 60Co and one plant did not detect the presence of 60Co. According to previously established procedures, these six plants were revisited after a period of time in which internal recalibration and corrective actions could be made. Four of the six plants had results which were still outside 1 SD of the mean for the original study. A final report in coded form to protect plant anonymity was provided to those stations to guide them in making further improvements, if they chose to do so.

Duodenal and antral mucosal prostaglandin E2 synthesis in a study of normal subjects and all stages of duodenal ulcer disease treated by H2 receptor antagonists.

We tested the hypothesis that the production of prostaglandin E2 (PGE2) is impaired in duodenal ulcer disease and affected by treatment and healing. This was investigated by a study of maximal PGE2 synthesis rates in duodenal and antral mucosal biopsies obtained at endoscopy. The patients were divided into three groups. Group (a): endoscopically normal controls (n = 56); group (b): treatment controls (non-DU disease: gastric ulcer or oesophagitis treated by histamine H2 receptor antagonists) (n = 41); and group (c): patients with DU disease (n = 183) further subdivided into group (c1) active ulcer not on treatment (n = 47), (c2) treated active ulcer (n = 35), (c3) healed ulcer on treatment (n = 86), and (c4) healed ulcer not on treatment (n = 15). Group (a) synthesised (mean (SD] 106.6 (39.0) pg PGE2/mg wt of tissue from the duodenal bulb and 129.9 (56.9) from the second part of the duodenum. No difference was found between group (a) and (b) at either site. Group (c1) ulcer rim made 49.8 (22.7) and at all stages ulcer rim and scar made less than the control duodenal bulb (p less than 0.02). Uninvolved duodenal bulb form groups (c1) (63.4 (31.0], (c2) (83.6 (38.5], and (c3) (81.5 (31.1], however, also made significantly less than controls (p less than 0.02) and a similar though non-significant trend was seen in group (c4). Biopsies from the second part of the duodenum did not synthesise significantly less than the control group but a similar trend was noticed at each stage of ulcer treatment. Biopsies of control antrum synthesised 124.5 (32.2) but only 93.7 (44.2) in group (cl) (p < 0.005). All stages of duodenal ulcer healing were associated with a decreased capacity to synthesise the major prostaglandin PGE2 at the ulcer site and the uninvolved duodenal bulb and, in acute untreated duodenal ulcer, the uninvolved antrum. This decreased capacity may be the consequence of the disease process itself and not secondary to the treatment, indicating a basic pathophysiological abnormality which may explain the characteristic tendency of the disease to relapse.

Changes in serum lipids related to the presence of experimental colon cancer.

People at risk from coronary heart disease and large bowel cancer are drawn from the same urbanised, industrialised Western populations. Whilst changes in blood lipids are well recognised in heart disease, little is known of their role in large bowel cancer. This study investigates serial alterations in blood lipids in the 1,2-dimethylhydrazine (DMH) rat model of colon cancer. Eighty Wistar rats received a 5 weekly regimen of DMH. At week 10, and at 5 weekly intervals until week 40, random groups of 10 rats were killed and blood taken for total and free cholesterol, phospholipids, triglycerides and liver enzymes. All colonic neoplasms were histologically classified either as adenomas or carcinomas with groups being allocated into tumour-free (n = 16) or tumour-bearing (n = 54), the latter group being further sub-divided into animals with adenoma alone (n = 8) and those with carcinoma (n = 46). Results were considered both sequentially and according to tumour status. Sequential results showed that with increase in colonic neoplasms with time there were accompanying increases in free and % free cholesterol and in phospholipids (P less than 0.001). There were no changes in total cholesterol, triglycerides or liver enzymes. Results according to tumour status showed that whilst there was no difference in total cholesterol or triglycerides between tumour-free and tumour-bearing rats, there was a significant increase in free (P less than 0.01) and % free cholesterol (P less than 0.001) and a decrease in phospholipids in the tumour-bearing animals (P less than 0.001). There was no difference in any serum lipid between tumour-free and adenoma-bearing rats. In animals with carcinoma, while there was no difference in total cholesterol or triglycerides, there was an increase in free (P less than 0.005) and % free cholesterol (P less than 0.001) and a decrease in phospholipids (P less than 0.001) compared to tumour-free rats. The data show for the first time a clear relationship between blood lipids and the presence or absence of large bowel cancer.

Bypass induced liver disease: an experimental study of the effect of post-operative protein supplementation and metronidazole therapy in an animal model.

An animal model of jejuno-ileal bypass (JIB) with post-operative weight loss and liver dysfunction was established in the rat. The role of a protein supplemented diet and post-operative metronidazole was investigated using this model. The use of a protein supplemented diet alone markedly reduced the detrimental effects of JIB. Although a beneficial effect was also noted with post-operative metronidazole, it was less marked and there appeared to be no additive benefit when both were used together. The results of this study would support the routine use of a protein enriched diet post-operatively in patients undergoing JIB.

The effects of particle size and moisture content on the emanation of Rn from coal ash.

Measurements of the emanation coefficients of 222Rn from coal ash were performed. Samples of coal ash from a stoker-fired furnace were mechanically sized into four categories. The mean 226Ra concentration of these categories ranged from 11.82-16.77 dpm g-1 and increased as a function of decreasing particle size. The mean bulk density and mean specific gravity of these categories ranged from 0.488-0.944 g cm-3 and 2.017-2.390 g cm-3, respectively, and both increased as a function of decreasing particle size. Samples of coal ash from four pulverized coal-fired furnaces were obtained, and demonstrated mean 226Ra concentrations ranging from 6.44-7.59 dpm g-1. The mean bulk density and mean specific gravity of these samples ranged from 1.254-1.520 g cm-3 and 2.357-2.588 g cm-3, respectively. Construction of chambers and methods for measuring 222Rn emanation coefficients are described. The measured emanation coefficient is shown to be insensitive to ingrowth time at times greater than three days. Measurements of emanation coefficients from ash samples were conducted at moisture contents of 0, 1.0, 10, 20 and 40% moisture by weight, and showed an increase in the emanation coefficient as a function of moisture content up to about 20% moisture by weight. Above 20% moisture content, most samples showed a trend toward decreasing emanation coefficients. The fractionated ash samples showed an increase in the emanation coefficient as a function of decreasing particle size. An experiment was also conducted which confirmed that sample depth was insignificant in explaining the observed emanation coefficient over the range of depths used in the other experiments.

Measurement of blood cortisol and acid output in patients with duodenal ulceration and normal subjects during insulin hypoglycaemia.

The blood cortisol and gastric acid responses to insulin hypoglycaemia were investigated in 18 healthy control subjects and 14 patients with endoscopically proven duodenal ulceration. In both controls and patients, insulin hypoglycaemia caused blood cortisol and acid output to rise and peak simultaneously, the rises being significantly greater in patients with duodenal ulcer than in control subjects. The peak acid output and the base to peak cortisol increments were also found to be significantly greater in patients with duodenal ulcer than in control subjects (P less than 0.001 and P less than 0.005 respectively). We conclude that insulin hypoglycaemia causes stimulation of the sympathetic and parasympathetic nervous systems and of the hypothalamo-pituitary-adrenal axis, resulting in the simultaneous elevation of gastric juice acidity and blood cortisol levels. We have shown that synchronous rises in gastric acid and blood cortisol occur during insulin hypoglycaemia and that these rises are greater in patients with duodenal ulcer.

Are prostaglandins cytoprotective in the human large intestine? The effect of indomethacin on rectal mucosal function and prostaglandin E2 release in vivo.

To test the hypothesis that prostaglandins are cytoprotective in the human large intestine, we investigated the effect of withdrawal of treatment with indomethacin suppositories on bowel habit and on rectal mucosal electrolyte transport and prostaglandin production in 8 patients taking such treatment for rheumatological disorders. Discontinuation of indomethacin doubled rectal mucosal prostaglandin E2 release (p less than 0.05) measured by in vivo rectal dialysis. Although there was no significant overall change in stool frequency, stool consistency, rectal bleeding or sodium absorption (also assessed by rectal dialysis), sigmoidoscopic appearance (p = 0.05), rectal mucosal potential difference (p less than 0.05) and potassium transport (p = 0.01) each reverted towards normal on indomethacin withdrawal. These results accord with the theory that, as in the upper gastrointestinal tract, prostaglandins may play a role in the maintenance of rectal mucosal structure and function.

Evaluation and testing of in vitro labeled technetium Tc-99m red blood cells in two animal models for neonatal RBC volume determinations.

The present study was designed to evaluate the red blood cell (RBC) radiolabeling technique utilizing the short half-lived radionuclide technetium-99m and to compare the results with the well-recognized standard chromium-51 method. The procedure was evaluated in a canine and a newborn lamb model utilizing dual radionuclide labeling and counting techniques. With the express purpose of providing a significant radiation dose reduction, the procedure presented was adapted for utilization in a neonatal patient population. Statistical analysis of the data revealed that there was no significant difference in the radiolabeling efficiency for the two methods (Cr-51, 86.6%; Tc-99m, 92.4%). Assessment of the in vitro stability for technetium-99m RBCs showed that less than a 4% loss of radiolabel from the RBC was seen in a 4-hr time span in the canine model (15 min, 90.5%; 2 hr, 88.9%; 4 hr, 86.6%) when compared to the 15 min equilibrium sample. Evaluation of newborn lamb RBC volumes showed that the technetium-99m RBC volume did not significantly differ from the chromium-51 labeling technique (Cr-51, 24.0 ml/kg; Tc-99m, 23.2 ml/kg). Summarization of the whole-body radiation dose showed that greater than a 30-fold reduction in absorbed dose was achieved in the newborn (Cr-51, 30.0 mrad; Tc-99m, 0.9 mrad). The modified procedure presented for the radiolabeling of the RBC with the short half-lived radionuclide technetium-99m provides a technique comparable to the utilized standard chromium-51 RBC method, yet with a large reduction in absorbed radiation dose. This procedure is presented as a superior technique for the determination of pediatric RBC volumes.