Consumption and diffusion of dissolved oxygen in sedimentary rocks

Fe(II)-bearing minerals (e.g., biotite, chlorite, and pyrite) are a promising reducing agent for the consumption of atmospheric oxygen in repositories for the geological disposal of high-level radioactive waste. To estimate effective diffusion coefficients (D_e, in m²s^-1) for dissolved oxygen (DO) and the reaction rates for the oxidation of Fe(II)-bearing minerals in a repository environment, we conducted diffusion-chemical reaction experiments using intact rock samples of Mizunami sedimentary rock. In addition, we conducted batch experiments on the oxidation of crushed sedimentary rock by DO in a closed system. From the results of the diffusion-chemical reaction experiments, we estimated the values of D_e for DO to lie within the range 2.69×10^-11<D_e<6.30×10^-11. Values of the second-order rate constant (k, in Lmol^-1s^-1) were in the range -3.66<log k<-2.83 (from batch experiments) and in the range -3.87<log k<-2.22 (from diffusion-chemical reaction experiments). Many of these values are within the range of previously published rates for reaction between O_2(aq) and Fe(II) surface complexes. The average value for the total concentration of reactive sites was about 10^-4molm^-2 from batch experiments. In contrast, the value of reactive sites estimated from the physical surface area was about 10^-8molm^-2, indicating that the reaction within intact rock is limited to the sites that originally existed with accessible porosity for O_2(aq). This difference arises because the batch experiments used powdered samples, meaning that new sites which formed during milling were added to the original reaction sites. On the basis of these observations and interpretations, diffusion-chemical reaction experiments make it possible to determine the values of the kinetic parameter and diffusivity for an intact rock sample simultaneously.

Discerning alumina ball wear from confounding metal transfer artifact

On dismounting a ceramic femoral ball from its metal trunnion, there is usually a range of gray metallic bands transferred to the trunnion bore inside the ball. This creates an artifact that may compromise detection by weight of the exceedingly low wear rates of ceramic balls. The objective of this study was to compare the weight trending of the metal trunnions and their ceramic balls during conditioning studies. Our hypothesis was that a pretest conditioning protocol would eliminate or greatly reduce the metal transfer artifact. The balls and tapers were placed on a hip simulator under 300-600 load cycles but with no articulation. The balls were then dismounted from the trunnions, and both were cleaned and weighed. This was repeated 6-23 times. We developed a novel hydraulic method for dismounting balls from trunnions that proved to be safe and efficient. There was significant weight loss in the trunnions after the ball removal, but there was no corresponding weight gain in the alumina balls. The weight effect of the metal transfer appeared to have been removed from the balls with our standard cleaning procedures. Therefore, wear rates for alumina balls may be gravimetrically determined without compensating for the metal transfer from trunnion to ball.

Long-term morphological changes of remnant pancreas and biliary tree after pancreatoduodenectomy on CT

BACKGROUND

Despite the increasing number of long-term survivors after pancreatoduodenectomy, little is known about morphological appearance of the remnant pancreas or the biliary system after surgery.

METHODS

To evaluate long-term morphological changes of the remnant pancreas and biliary tree after pancreatoduodenectomy, computed tomograms obtained at the time of surgery and more than 2 years after operation were reviewed in 19 Japanese patients.

RESULTS

Two to three years after surgery, parenchymal atrophy of the remnant pancreas occurred in 9 (56%) of 16 patients without atrophy at the time of surgery. Three patients who had had parenchymal atrophy preoperatively showed no change after surgery. Of 10 patients with a dilated pancreatic duct preoperatively, 8 (80%) patients demonstrated a decline in ductal size, while the other 2 showed persistent ductal dilatation. Of 9 patients with a normal-sized pancreatic duct preoperatively, 2 patients (22%) developed ductal dilatation after surgery, and the other 7 showed no change. In 4 (57%) of 7 patients with a dilated hepatic duct preoperatively dilatation was reduced after surgery, whereas it persisted in the remaining 3. Only one (8%) of 12 patients with a nondilated biliary tree preoperatively showed ductal dilatation 6 months following surgery. Pneumobilia was revealed in 13 (68%) of 19 patients by the follow-up examinations.

CONCLUSIONS

Surgeons should be aware of these changes in morphology of the remnant pancreas and biliary tree after pancreatectoduodenectomy.

Disseminated pancreatic polypeptidioma

Pancreatic polypeptidioma, a pancreatic endocrine tumor, is an extremely uncommon disease and its clinical features and responses to therapy are not well known. We present a 33-year-old woman with disseminated pancreatic polypeptidioma, who subsequently showed various signs and symptoms of metastases, including bone pain, cranial nerve palsy, spinal block, and hematuria, and died 22 months after the presentation. Responses to various therapeutic regimens including hepatic arterial embolization, radiation therapy, systemic chemotherapy, and administration of interferon-alpha or somatostatin analogue, are discussed. Particular note in this case is a prompt response of bone metastases to the radiotherapy.

Analysis of human vaginal secretions by SDS-polyacrylamide gel electrophoresis

Proteins in 68 vaginal secretions from 50 women were analyzed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Although there were considerable numbers of intermediate types, the secretions could be classified into the following groups based on the densitometric patterns. A relatively low concentration of 67K protein (albumin) and a high concentration of 52K protein (IgG) were the patterns common to pre- and post-menstrual phases and pregnant stadium. A relatively high concentration of the 67K protein and a moderate concentration of the 52K protein characterized the midcycle. A considerably high concentration of 67K protein compared with the 79K (transferrin), 58K (IgA) and 52K bands was the pattern for menstrual phase and postpartum stage.

LH discharge induced by medial preoptic implantation of estrone or dopamine in the ovariectomized estradiol primed rat

Effect of implantation of estrogens or catecholamines into the medial preoptic area through chronically implanted double cannula on the release of LH was examined in the ovariectomized estradiol-primed rat. Implantation of estrone at 12:00 on the second or third day after subcutaneous injection of estradiol benzoate (20 mug) increased the serum concentration of LH at 18:00 compared with that in the non-implanted controls, whereas implantation of estradiol benzoate on the third day did not affect it. Dopamine implantation at 12:00 on the third day also induced a significant increase of LH concentration at 18:00, and, in contrast, norepinephrine implantation decreased the concentration at 18:00. It may be said that the medial preoptic area is responsive to estrone and can induce LH release, whereas it is not to estradiol. Furthermore, dopamine was effective for the activation of the medial preoptic area in relation to the inducement of LH release.