U-shaped Configuration Research Articles

PURE LAPAROSCOPIC ENTEROCYSTOPLASTY

The realm of laparoscopic surgery has expanded from simple extirpative operations to more complicated reconstructive procedures, such as dismembered pyeloplasty and ileal conduit creation. There has been recent interest in using laparoscopic techniques to augment the bladder with bowel.1, 2 To date only 1 case of enterocystoplasty, using the stomach, has been accomplished entirely by laparoscopy.3 To our knowledge we report the first case of ileal enterocystoplasty performed completely by laparoscopy. CASE REPORT A 31-year-old paraplegic woman with a C6 spinal cord injury developed worsening voiding dysfunction during the 2 years preceding presentation. She had managed previously with clean intermittent catheterization every 4 hours and remained dry. Video urodynamic studies demonstrated detrusor instability at bladder volumes of 40 to 50 ml. and a maximum bladder capacity of 85 ml. The patient did not desire urinary diversion or a continent cutaneous reservoir, and opted instead for laparoscopic ileal bladder augmentation. Mechanical and antibiotic bowel preparation was performed, and externalized ureteral stents were initially placed. The remainder of the operation duplicated open augmentation cystoplasty using an ileal segment. Briefly, 5 ports were used and the ileum was identified 15 cm. from the ileocecal valve. An endoscopic gastrointestinal anastomosis stapler was used to isolate a 15 to 20 cm. segment of ileum, and the mesentery was incised with ultrasonic coagulating shears. Bowel continuity was restored in a side-to-side fashion using a gastrointestinal anastomosis stapler, with the enterotomy closed in a single layer with interrupted 2-zero silk Lembert sutures. Monopolar electrocautery was used to remove the staples from both ends of the isolated ileal segment and detubularize it on its antimesenteric border. The ileum was sutured into a U-shaped configuration using a single layer of running 3-zero polyglactin sutures prior to mid sagittal cystotomy. The ileal patch was sutured to the bladder in quadrants using running 3-zero polyglactin sutures. Drainage was provided by a 20Fr urethral catheter and a 10 mm. Blake drain brought out through a lateral port site. No suprapubic catheter was placed. Watertight closure was confirmed by intraoperative irrigation of the bladder. Estimated blood loss was 100 ml. and there were no intraoperative complications. On the third postoperative day the drain was removed and the patient resumed liquid intake. However, she remained hospitalized due to prolonged ileus for 13 days. She returned to work and normal activity 1 week after being discharged. A cystogram performed 4 weeks postoperatively, at the time of catheter removal, demonstrated a bladder capacity of at least 250 ml. (see figure). Presently, the patient is continent between catheterizations with urinary volumes approximating 400 ml. DISCUSSION

New U-shaped Components for Metallosupramolecular Assemblies: Synthesis and Coordination Chemistry of 2,6-bis(4-(3-pyridyloxy)phenoxy)pyrazine

The new ligand 2,6-bis(4-(3-pyridyloxy)phenoxy)pyrazine ( L ) has been prepared and characterised. Reaction with a palladium (II) precursor yields a discrete complex of formula [Pd( L ) 2 ](ClO 4 ) 2 , in which the ligand coordinates in a U-shaped fashion through the pyridine groups only, resulting in the complex containing two 22-membered chelate rings ( a =15.288(9), b =10.118(4), c = 22.720(12), g =95.450(12), P 2 1 / n , Z =2, calcd =1.413 g cm m 3 , 507 parameters, R =0.0433). Reaction with silver nitrate yields a metallocyclic complex of formula [Ag 2 ( L ) 2 (NO 3 )](NO 3 ), in which each silver is bound to one pyridine group of two different ligands, each of which is again in a U-shaped configuration ( a = 12.215(9), b =12.759(9), c =19.461(14), f =90.949(10), g =103.214(10), n =110.327(11), P m 1, Z =2, calcd = 1.591 g cm m 3 , 755 parameters, R =0.0287).

Three-dimensional geometric sensitivity calculation for three-headed coincidence imaging

All major gamma camera manufacturers nowadays offer two-headed coincidence imaging with their gamma camera systems. To improve sensitivity, three-headed coincidence imaging has been proposed. In an earlier work, the authors investigated how the two-dimensional sensitivity varies in the field of view of such a system. Here, these calculations are extended to three dimensions, taking into account the finite axial length of the detector. The extension to three dimensions becomes particularly important when one acquires data in fully three-dimensional mode, without using axial septa. The three-dimensional sensitivity calculation presented here is valid for any position of the camera, such as a U-shaped configuration or a triangular configuration. The authors have also investigated the use of axial septa by constraining the maximum axial incidence angle.

Bolaamphiphilic Phosphocholines: Structure and Phase Behavior in Aqueous Media

The phase behavior of 1,1‘-di-O-eicosamethylene-2,2‘-di-O-decylbis(glycero-3-phosphocholine) (1) and 1,1‘-di-O-hexadecamethylene-2,2‘-di-O-octylbis(glycero-3-phosphocholine) (2) was studied at the air−water interface and in aqueous dispersions using monolayer film balance, small-angle X-ray scattering, Raman spectroscopy, and cryo-TEM techniques. The limiting molecular areas (20 °C, pH 6.8) were observed to be 172 Å2 for 2 and 105 Å2 for 1, indicating a U-shaped configuration of the long polymethylene chains at the air−water interface. The larger molecular area of 2 relative to 1 at the air−water interface suggests that the alkyl chains of 2 are less ordered than those of 1 at similar pressures. The extrapolated d spacings for 1 from SAXS experiments were 32 Å in the liquid crystalline lamellar phase and 40 Å in the gel phase where the hydrocarbon chains are in their all trans configuration. The extrapolated d spacings for 2 were 27 and 33 Å in the liquid crystalline and gel phases, respectively. DSC analysis revealed phase transition temperatures of 1 and 2 in excess water at 15.3 and −23.5 °C, respectively, with observed transition enthalpies of 9.1 and 2.9 kJ/mol, respectively. These values are in good agreement with Raman spectroscopy experiments that detect alkyl melting transitions near these temperatures. Addition of 30 mol % cholesterol to both bolaamphiphile samples lowered the observed transition temperatures (1, 9.5 °C; 2, −25.1 °C) and enthalpies (1, 5.7 kJ/mol; 2, 2.5 kJ/mol), suggesting that cholesterol reduces the transition cooperativity. Extruded samples of pure 1 in buffer (30 mg/mL in 20 mM Tris, pH 8) produced vesicle structures that were variable in size (0.15−1.5 μm), with multilamellar and nonspherical morphologies apparent. Incorporation of cholesterol in the extruded samples (7:3 1/Chol), however, gave stable spherical unilamellar vesicles with a mean diameter of 857 ± 237 Å. Similar results were observed for dispersions of 2 and 7:3 2/Chol. These results suggest that stable, unilamellar monolayer membrane vesicles can be formed from bolaamphiphiles with relatively short (C16 and C20) membrane-spanning alkyl chains.

Transcranial Cortical Magnetic Stimulation of Lower-Lip Mimetic Muscles: Effect of Coil Position on Motor Evoked Potentials

The effect of the coil position along the interaural line on motor evoked potentials of lower-lip muscles to cortical transcranial magnetic stimulation was investigated in 17 healthy subjects. Using a figure-8-shaped coil, we observed ipsi- and contralateral middle-latency motor evoked potentials in all subjects, when the coil was centered within an area between 4 and 13 cm lateral to the vertex. Maximal responses (mean amplitude 1.4 ± 0.8 mV contralateral, 0.7 ± 0.5 mV ipsilateral) with shortest mean onset latencies (11.3 ± 1.6 ms contralateral, 12.1 ± 2.8 ms ipsilateral) were obtained at a stimulus position of 10 cm lateral to the vertex. Cortical maps of mean amplitude and mean response duration showed inverse U-shaped configuration. Furthermore, we observed an additional polyphasic and mostly bilateral response in 16 of the 17 subjects.

Repaglinide, a new oral antidiabetic agent: a review of recent preclinical studies.

Repaglinide is a new carbamoylmethyl benzoic acid derivative that is structurally related to meglitinide. In common with all active oral hypoglycaemic agents, it displays a comparable U-shaped configuration. Repaglinide exerts its effects by binding to a site on the plasma membrane of beta-cells, thereby closing ATP-sensitive potassium channels. This causes depolarization of the beta-cell and the opening of voltage-sensitive calcium channels allowing the influx of extracellular calcium ions. This increase in intracellular calcium, in turn, stimulates insulin release. The insulinotropic effect of repaglinide is not related to its ionophoretic capacity. Repaglinide does not cause insulin release in the absence of exogenous glucose, nor does it inhibit the biosynthesis of proinsulin. In vivo administration of an ester of succinic acid potentiates the insulin secretory response to concomitantly administered repaglinide. Repaglinide causes a more rapid increase in plasma insulin levels in rats than either glibenclamide or glimepiride.

Experimental studies of circular patches with slots

Experimental results for circular patches with slots are presented. Two configurations are studied, one with an arc-shaped slot and the other with a rectangular U-shaped slot. About 14% impedance bandwidth is obtained for the former and 23% for the latter. Measured patterns and gain are also given for the U-shaped slot configuration.

Interfacial air/water proton conduction from long distances by sulfolobus solfataricus archaeal bolaform lipids.

The stability, structural organization, and the ability to transfer protons long distances have been investigated in monolayers formed from archael bolaform lipids at the air/water interface. The lipids employed were the fractions GroR2Gro (R represents an acyl group with variable chain length typically consisting of 0-4 cyclopentane rings and 40 isoprenoid residues) and GroR2GroNon-Ol (Non-ol represents nonitol) extracted from Sulfolobus solfataricus by hydrolysis of the cytoplasmic membrane. GroR2-GroNon-ol films exhibit a very peculiar behaviour: the monolayer surface pressure increases with time, regardless of its low or high initial value. This finding is related to the possibility of GroR2GroNon-ol molecules to assume an upright (a metastable) or a U-shaped (stable) configuration. In the gaseous state and in the collapsed state of the film, no lateral proton conduction was observed. However, in the pressure range 0 < pi < 25 mN/m for GroR2Gro and 0 < pi < 30 mN/m for GroR2GroNon-ol monolayers, a lateral proton conduction at the air/water interface was observed. The structural organization of these bipolar lipids at the air/water interface can be related to the lateral proton conduction; it is possible to conclude that whatever configuration these lipids may adopt, they are able to structure the air/water interface in a hydrogen bond network that supports lateral proton conduction. This process may be ascribed to a percolation phenomenon occurring when the polar lipid head groups form a structured lattice of hydrogen bonds.

PHARMACOLOGY OF THE HYPOGLYCAEMIC SULPHONYLUREA GLIQUIDONE III. CONFORMATIONAL ANALYSIS

The hypoglycaemic sulphonylurea gliquidone was found, by conformation analysis, to display a U-shaped configuration, with hydrophobic cycles placed at the extremity of each branch and a peptidic bond placed at the bottom of the U. This configuration is similar to that recently observed with the hypoglycaemic sulphonylureas glimepiride and glibenclamide and non-sulphonylurea hypoglycaemic agents of the meglitinide family, such as S3075, repaglinide, A-4166 and KAD-1229. The identification of a conformation common to these various hypoglycaemic drugs may provide an imprint of their binding site at the level of the B-cell sulphonylurea receptor.

High transition velocities for solid armatures in the 10-mm MTR railgun

The transitioning of a solid armature on the Materials Test Railgun (MTR) was studied, and data on high-velocity transitions were analyzed. The railgun has a 10-mm square bore, is 0.6-m long, and is designed with a bolted construction for experimental flexibility. Solid 7075-series Al alloy armatures were accelerated to 1.75 km/s, and transition was observed at approximately 1.3 km/s. These 3-g armatures were designed in a U-shaped configuration. The railgun was driven by a stored energy of 200 kJ from the USA ARDEC (Armament Research Development and Engineering Center) 10-kV capacitor bank power supply. The test configuration, armature design, and shot data are provided. The muzzle voltage data were analyzed using model equations for the transitioning of the solid armature to a hybrid armature with arcing contacts. The data clearly show the development of the voltage as a continuous process involving the various phases for the contacts and the model reflects this behavior. >

Unhooking Dynamics of U-Shaped DNA Molecule Undergoing Gel Electrophoresis

It has been found that DNA molecules are often hooked around obstacles in a U-shaped configuration in gel electrophoresis. To understand the dynamics of the unhooking of U-shaped DNA molecules undergoing gel electrophoresis, we have examined the length changes of the longer and shorter arms of the U-shape as a function of time. Two types of unhooking have been found. In one type, the length changes of both arms are expontential in time but with different time constants. In another type, the length changes of the shorter arm is exponential and that of the longer one is linear with time. The interpretation is that the extent of stretch of the spring-like DNA chain decreases as the length difference between the two arms increases during the unhooking processes, and that the frictions at the pivot point can be relatively large depending upon the local structure of the gel. The friction coefficient at the pivot point is estimated to be nu 0 = (2.98 +/- 1.42)x10(-5) g/sec.

Controlled Burning of Crude Oil on Water Following the Grounding Of the Exxon Valdez

ABSTRACT During the evening of the second day following the Exxon Valdez oil spill, an estimated 15,000 to 30,000 gallons (57,000 to 114,000 L) of North Slope crude oil were eliminated using in-situ combustion techniques. The oil was collected with the 3M Company's Fire Boom, towed in a U-shaped configuration behind two fishing boats. Working with 500-foot (152-m) tow lines, a 450-foot (137-m) boom was moved at about one-half to one knot (0.26 to 0.52 m/s) through slightly emulsified oil patches downwind of the spill. Once oil had filled the downstream portion of the U-shaped boom and the boats were clear of any surrounding slicks, a gelled-fuel igniter was released from one of the tow boats. Shortly after ignition, flames gradually spread out over the entire area of the contained oil. As flames reached 200 to 300 feet (61 to 91 m) into the air, the area of the contained oil layer (and therefore the size and intensity of the fire) could be controlled by adjusting the speed of the vessels. The total burn time was approximately 75 minutes; however, the intense part of the burn lasted for about 45 minutes. The original volume of oil, likely between 15,000 and 30,000 gallons, was reduced to approximately 300 gallons (1,136 L) of stiff, taffy-like burn residue that could be picked up easily upon completion of the burn. The controlled elimination of crude oil therefore resulted in an estimated 98 percent or better efficiency of burn.

Audiological Findings in Acoustic Neuroma

Audiological examinations are vital in the diagnosis of acoustic neuroma. In interpreting their results, however, it is necessary to consider the patient's hearing level. The most sensitive audiological examination is auditory brain stem response (ABR) audiometry. Its most useful parameter is the IT5. A U-shaped audiometric configuration suggests AN, since it is seen in 10% of patients with small tumors. Psychological audiometric tests can be excluded from the battery of screening tests since they have low rates of positive diagnosis. The stapedius reflex (SR) test also has a low positive diagnostic rate in cases of small tumors. Even with the parameters of absence of reflex, elevated threshold, and decay combined, the overall SR test has a lower positive diagnostic rate than ABR audiometry. Nevertheless, the SR test can be employed as a screening device in cases in which the hearing level at 2 kHz and lower is 70 dB or lower, even if it is 71 dB or higher at 4 kHz and 8 kHz. At present, ABR audiometry is applicable in only about half of AN cases. Therefore, the need for early diagnosis must be further emphasized.

Orientation of diplochromosomes in mitoses of potato (Solatium tuberosum L.) callus cultures

The mitotic behaviour of diplochromosomes was investigated in early calli from leaf segments of a monohaploid potato (x = 12) with the aid of the fluorescent plus Giemsa technique. The sister chromosomes of the diplochromosomes do not separate during metaphase because the inner chromatids remain connected. Consequently the diplochromosomes orient in three stable configurations during metaphase. In the case in which sister chromosomes become auto-oriented, the outer chromatids face one pole and the inner chromatids the opposite pole (U-shaped configuration), or the outer and inner chromatid of each sister chromosome face different poles (alternate configuration). Less frequently the sister chromosomes become oriented to different poles (C-shaped configuration). Linear orientation is not observed. At least until the onset of telophase only the inner chromatids originating from U-shaped configurations may remain paired, but they fall apart before the next metaphase. The mitoses with diplochromosomes give rise to two cells with double the number of chromosomes.Key words: potato, diplochromosomes, mitosis, orientation, polyploidization.

An elliptical cylinder-type shielding device using amorphous ribbons

A novel elliptical-cylinder-type shielding device for static magnetic fields is presented. This device consists of two domes using 25- mu m thick METGLAS 2826-MB amorphous ribbons. Amorphous ribbons were attached to the legs of the domes in a U-shaped configuration. The U-shaped amorphous ribbons are magnetized by an external field, and a demagnetizing field was set up to cancel the external field. Shielding effectiveness can be controlled easily by adjusting the length of the U-shaped amorphous ribbons and the distance between the apexes of the domes. A shielding factor defined as external field intensity/internal field intensity becomes higher than 10/sup 3/ when the demagnetizing field of the U-shaped amorphous ribbon completely cancels the external field. >

The many uses of the U tube

U tube placement was employed as an adjunct to complicated biliary procedures in 14 patients. We found the transhepatic tubes to be useful for stenting biliary anastomoses, maintaining biliary drainage, delivering localized irradiation, and acting as permanent external conduits. The tubes remained in placed an average of 15 months and as long as 40 months. The freguency of cholangitis was minimized by frequent tube exchange. The U-shaped configuration makes tube exchange easy and inexpensive to perform.

Imaging performance of mirror pairs for grazing-incidence applications: a comparison

The eight distinct reflection configurations for pairs of toroidal mirrors are investigated by numerically calculating their aberration patterns for on- and off-axis source points. The best performance is obtained for a Z-shaped configuration where the two mirrors deflect in opposite directions across a common interior sagittal and tangential focus. Imaging properties can be improved significantly in some cases by replacing the toroidal elements with their elliptical or parabolic equivalents. The best overall performance is obtained with parabolic mirrors in a U-shaped configuration.

Improved optical probe for monitoring dust explosions

An improved optical probe was developed to monitor dust-cloud concentration in explosions even in the presence of dust flame radiation. Principal features of the probe include a pulsed light-emitting diode and a photodetector with optical interference filter to reduce flame radiation. The probe has a U-shaped configuration and air jets to keep the windows dust free. Experimental data are presented for a coal dust explosion.

Relationships between road accidents and hourly traffic flow—II: Probabilistic approach

This is a continuation of the investigation into relationships between accident rate and hourly traffic flow as outlined in Part I of the research. The underlying study attempts to determine appropriate models for single- and multi-vehicle accident rates in conjunction with free-flow and congested-flow conditions. For the free-flow data, the total accident rate-hourly flow curve follows the U-shaped configuration. This form is the result of a convex downward and a convex upward curve for single- and multi-vehicle accidents, respectively. For the congested-flow data (characterized by multi-vehicle accidents), the accident rate increases sharply with hourly flow. The models are applied to probabilistic aspects with consideration of a fitted, generalized (hourly flow dependent) headway model. The headway model represents the probability that two vehicles which are, even instantaneously, under a car-following mode are in a potentially hazardous situation. The approach investigated is believed to provide an essential input for both simulation studies and theoretical models of road traffic accidents.

Dust cloud concentration probe

An optical probe was developed to measure dust cloud concentration during the propagation of dust flames or explosions. Principal features of the probe are a miniature light-emitting diode and photosensor in a U-shaped configuration and air jets to keep the windows of the device dustfree.