We examined the function of the accessory pancreatic duct (APD) in 56 cases of the pancreaticobiliary maljunction. APD existed in 11 of 26 cases of the congenital choledochal cyst. The maximal ...diameter of APD was over 2 mm in 5 cases. Patency of APD was detected in 5 of 9 cases examined by dye-injection endoscopic retrograde pancreatography (ERP). APD existed in 15 of 30 cases of the pancreaticobiliary maljunction without biliary dilatation, and all APDs were less 2 mm in diameter. By dye-injection ERP, APD was patent in 4 of 13 cases. There was no significant relationship between patency of APD and associated biliary carcinoma in the cases of the pancreaticobiliary maljunction, but 5 cases of the congenital choledochal cyst with APD bigger than 2 mm in diameter had no biliary carcinoma. Amylase level of the bile in cases of the pancreaticobiliary maljunction with patent APD was frequently lower than that of cases with nonpatent APD. It is suggested that in cases of the pancreaticobiliary maljunction with patent APD, the incidence of carcinogenesis of the biliary tract might be lower, as the reflux of the pancreatic juice to the bile duct might be reduced by the flow of pancreatic juice from the upper dorsal pancreatic duct into the duodenum via the minor duodenal papilla.
Diffraction rings corresponding to the first, second, and third order were obtained by laser light illumination from a suspension of rabbit glycerinated psoas myofibrils (diameter, 1–2 microns; ...average length of the straight region, 44 microns; average sarcomere length, 2.2–2.6 microns) of which the optical thickness was appropriately chosen. Dispersed myofibrils were nearly randomly oriented in two dimensions, so that the effects of muscle volume were minimized; these effects usually interfere significantly with a quantitative analysis of laser optical diffraction in the fiber system. The diameters of diffraction rings represented the average sarcomere length. By using this system, we confirmed the ability of the unit cell (sarcomere) structure model to explain the intensity change of diffraction lines accompanying the dissociation from both ends of thick filaments in a high salt solution. The length of an A-band estimated from the relative intensity of diffraction rings and that directly measured on phase-contrast micrographs coincided well with each other. Also, we found that myofibrils with a long sarcomere length shorten to a slack length accompanying the decrease in overlap between thick and thin filaments produced by the dissociation of thick filaments.
We have visualized, under an optical microscope, the orientations of actin monomers in individual actin filaments undergoing Brownian motion in solution, actively sliding past myosin molecules, or ...immobile on a surface. For the visualization, two strategies have been adopted. One is to exploit the fluorescence polarization of a fluorescent probe firmly attached to actin. Using the probe phalloidin-tetramethylrhodamine, the fluorescence was clearly polarized along the filament axis, showing alignment of the probe molecules along the filament axis. Within our temporal resolution of 33 ms and spatial resolution of better than 1 micron (average over approximately 10(2) actin monomers), the orientation of the probe (hence of actin monomers) did not change upon interaction of the filament with heavy meromyosin; myosin-induced reorientation was estimated to be a few degrees at most. This first method, while highly sensitive to small reorientations of monomers off or toward the filament axis, does not report on reorientations around the axis. To detect rotation around the filament axis, we adopted the second strategy in which we attached small plastic beads to the actin filaments. Axial turns would be immediately apparent from the movement of the beads. Preliminary observations indicate that actin filaments can slide over a heavy meromyosin-coated surface without axial rotations. Since rotations have been implicated in different experiments, we are currently investigating the source of the apparent discrepancy. The attached bead also serves as a handle through which we can apply force, via optical tweezers, on the filament. By letting the sliding actin filament pull the bead against the optical force, we were able to estimate the sliding force and its fluctuation.
The binding of 3Hpyrilamine, a selective ligand of histamine H1 receptors, to guinea pig brain in vivo was compared with its binding to a brain homogenate. The pharmacological properties (regional ...distribution, saturability, and stereoselectivity) of the 3Hpyrilamine binding in vivo were similar to those of the in vitro binding to brain homogenate. A dynamic four-compartment model was proposed for the analysis of the kinetics of 3Hpyrilamine binding in vivo. The receptor constants in vivo were determined by a computer-fitting method after correcting the radioactivity of arterial plasma and brain for the presence of radioactive metabolites. The in vivo association and dissociation were 213 and 42 times, respectively, slower than those of in vitro binding at 37 degrees C. A possible mechanism for slow association and dissociation in vivo is discussed.
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![Specific binding of [3H]pyr...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0022-3042/small "Specific binding of [3H]pyrilamine to histamine H1 receptors in guinea pig brain in vivo: determination of binding parameters by a kinetic four-compartment model")
