Triazolam-induced modulation of muscarinic acetylcholine receptor in living brain slices as revealed by a new positron-based imaging technique

The effect of triazolam, a potent benzodiazepine (BZ) agonist, on muscarinic acetylcholinergic receptor (mAChR) binding was investigated in living brain slices by use of a novel positron-based imaging technique. Fresh rat brain slices were incubated with [11C]N-methyl-4-piperidylbenzilate ([11C]NMPB), a mAChR antagonist, in oxygenated Krebs-Ringer solution at 37 degrees C. During incubation, time-resolved imaging of [11C]NMPB binding in the slices was constructed on the storage phosphor screens. Addition of triazolam (1 microM) plus muscimol (30 microM), a GABA(A) receptor agonist, to the incubation mixture decreased the specific binding of [11C]NMPB. Ro15-1788, a BZ receptor antagonist, prevented this effect, indicating that the effect was exerted through the GABA(A)/BZ receptor complex. These results demonstrated that stimulation of the GABA(A)/BZ receptor lowers the affinity of the mAChR for its ligand, which may underlie the BZ-induced amnesia, a serious clinical side effect of BZ. No such effect in the P2-fraction instead implies that the integrity of the neuronal cells and/or their environment is prerequisite for the modulation of mAChR by GABA(A)/BZ stimulation.     

Increased plasma levels of substance P and disturbed water excretion in patients with liver cirrhosis

We describe a surgical technique for replacing the hip joint capsule using synthetic mesh after oncological resections of the proximal femur that resulted in gross intraoperative instability of the prosthetic reconstruction. The results of its use in 13 patients, 6 of whom also had pelvic resections, are described. These patients were selected from a total group of 88 patients undergoing proximal femoral replacement, 75 of whom did not require capsular replacement (none of these 75 patients have experienced dislocation). In the group requiring capsular reconstruction, 1 of 4 patients with bipolar hemiarthroplasty and 4 of 9 patients with total hip replacements experienced dislocation after operation. Of the dislocated total hip replacements, 1 remains chronically dislocated, and 3 were successfully stabilized by open reduction with further capsular augmentation. Given that the resections involved removal of most of the soft tissues stabilizing the hip joint, we believe that the technique of capsular reconstruction is useful in this difficult group of patients.     

The significance of the morphology of the dorsal pancreatic artery in determining the presence of the accessory right hepatic artery passing behind the portal vein

The dorsal pancreatic artery (DP) and an accessory right hepatic artery (AcRH) passing behind the portal vein were investigated in 98 Japanese specimens. The dorsal pancreatic artery was identified in 87 specimens (88.8%). This artery has been found to yield the following 6 branches: (1) an inferior pancreatic artery (left branch, 83.9%); (2) a right branch-1 that serves as the prepancreatic arcade in front of the pancreas (77.0%); (3) an uncinate branch that distributes to the uncinate process (60.9%); (4) a head branch that distributes from the dorsal side of the pancreas to the head of the pancreas (newly defined in the present study, 60.9%); (5) a right branch-4 that distributes superior to the dorsal part of the pancreatic neck (39.1%); and (6) a right branch-5 that communicates with the posterior pancreaticoduodenal arcade (21.8%). In some cases, the above six branches are formed separately, i.e., two (18.4%) or three (5.7%) dorsal pancreatic arteries are present. The parent artery of the DP was the superior mesenteric artery (SM; 55.0%), accounting for 45.0% of the entire celiac trunk. An accessory right hepatic artery was identified in 18 specimens (18.4%). In cases where the AcRH originated from the entire celiac trunk (5 specimens, 27.8%), it always formed a common trunk with the DP. On the other hand, when the AcRH derived from the SM (13 specimens, 72.2%), it formed a common trunk with the DP 6 of the specimens (33.3%), independent branching was observed in 6 specimens (33.3%). And a common trunk with the inferior pancreaticoduodenal artery was observed in one specimen (5.6%). The dorsal pancreatic artery was considered to supply not only the AcRH but also other pathways that form more complicated variations such as an accessory middle colic artery.     

Modes in curved step-index optical fibres

By using parabolic, instead of circular, cylindrical co-ordinates the field distributions of the natural modes of curved step-index fibres can be described completely, yet simply. The mode caustics corresponding to the geometrical guiding limit of the equivalent rays of curved fibre can be clearly demonstrated. Near-field mode patterns and caustics obtained experimentally are in excellent agreement with the theory.     

Mechanism of feeding discrimination between matured and juvenile foliage by two species of pine sawflies

Two species of pine sawflies,Neodiprion rugifrons Midd. andN. swainei Midd., feed only on matured foliage of jack pine,Pinus banksiana Lamb., and leave juvenile or current-season foliage intact. This unique form of adaptation was studied from the viewpoint of the chemical ecology of this insect-host plant relationship. It was first determined that the differential larval feeding behavior reflects the presence of feeding deterrents. Two major biologically active substances were isolated and identified as 13-keto-8(14)-podocarpen-18-oic acid and dehydroabietic acid. These account for 63.5% and 24.6% of the total deterrency, respectively. The content of the former substance in current-year foliage decreases, as the foliage begins to mature, to the levels that become acceptable toN. swainei by August (60 days old) and to the second generationN. rugifrons by September (90 days old). The timing of their acceptance of juvenile foliage indicates the high levels of adaptation by these insects to allow oviposition for the on-coming adults and acceptable needles for the next generation of larvae. The level of dehydroabietic acid, on the other hand, does not change appreciably during the same time period: this indicates that the component does not play a significant role in the mechanism of differentiating juvenile from matured foliage by the sawfly larvae.     

Reduced pressure collapsing MCVD method for single polarization optical fibers

A simple fabrication method of single polarization optical fibers has been proposed. Core, clad, and jacket layers are deposited in a silica tube. The tube is then collapsed while the inner pressure of the tube is reduced. The core circularity and the jacket ellipticity are controlled by the careful selection of the softening points of core/clad and jacket materials, and the inner pressure. The pressure reduction and the softening points of the constituent glasses play an important role in fabricating single polarization optical fibers.     

Atomic Layer Epitaxy of Silicon

Two methods are proposed and demonstrated successfully for low temperature atomic layer epitaxy (ALE) of Si, where H atoms play essential roles. The first method is the use of H as a self-limiting factor. Trisilane (Si₃H₈) was used as source gas and the substrate temperature was modulated in order to alternate steps in an ALE cycle. When the temperature was less than 380°C in the adsorption step and more than 520°C in the desorption step, respectively, the grown layer thickness per cycle was 0.8 ML/cycle. The second method is the use of atomic H as an active reducer of a self-limiting factor. A clean surface was exposed to dichlorosilane (SiH₂Cl₂) as source gas to grow an Si monolayer covered with CI. Next, atomic H was injected to reduce CI from the surface. An ideal monolayer growth was obtained with the substrate temperature over 540°C.