Promoting Atoms into Delocalized Long-Living Magnetically Modified State Using Atomic Force Microscopy.

We report on a low-temperature atomic force microscropy manipulation of Co atoms in ultrahigh vacuum on an oxidized copper surface in which the manipulated atom is kept delocalized above several surface unit cells over macroscopic times. The manipulation employed, in addition to the ubiquitous short-range tip-generated chemical forces, also long-range forces generated via Friedel oscillations of the metal charge density due to Co nanostructures prearranged on the surface by lateral manipulation. We show that our manipulation protocol requires mechanical control of the spin state of the Co atom.

Atomic force microscopy identification of Al-sites on ultrathin aluminum oxide film on NiAl(110).

Ultrathin alumina film formed by oxidation of NiAl(110) was studied by non-contact atomic force microscopy in an ultra high vacuum at room temperature with the quest to provide the ultimate understanding of structure and bonding of this complicated interface. Using a very stiff Si cantilever with significantly improved resolution, we have obtained images of this system with unprecedented resolution, surpassing all the previous results. In particular, we were able to unambiguously resolve all the differently coordinated aluminum atoms. This is of importance as the previous images provide very different image patterns, which cannot easily be reconciled with the existing structural models. Experiments are supported by extensive density functional theory modeling. We find that the system is strongly ionic and the atomic force microscopy images can reliably be understood from the electrostatic potential which provides an image model in excellent agreement with the experiments. However, in order to resolve the finer contrast features we have proposed a more sophisticated model based on more realistic approximants to the incommensurable alumina interface.

Vertical atomic manipulation with dynamic atomic-force microscopy without tip change via a multi-step mechanism.

Manipulation is the most exciting feature of the non-contact atomic force microscopy technique as it allows building nanostructures on surfaces. Usually vertical manipulations are accompanied by an abrupt tip modification leading to a change of contrast. Here we report on low-temperature experiments demonstrating vertical manipulations of 'super'-Cu atoms on the p(2 × 1) Cu(110):O surface, both extractions to and depositions from the tip, when the imaging contrast remains the same. These results are rationalized employing a novel and completely general method that combines density functional theory calculations for obtaining energy barriers as a function of tip height and a Kinetic Monte Carlo algorithm for studying the tip dynamics and extraction of manipulation statistics. The model reveals a novel multi-step manipulation mechanism combining activated jumps of 'super'-Cu atoms to/from the tip with their drag by and diffusion on the tip.

Quantification of atomic-scale elasticity on Ge(001)-c(4 × 2) surfaces via noncontact atomic force microscopy with a tungsten-coated tip.

We investigated the bonding stiffness of individual atoms on substrate surfaces using noncontact atomic force microscopy with frequency modulation. We measured the frequency shift distribution of the (110) plane above buckling-up and buckling-down dimer atoms of the Ge(001)-c(4 × 2) surface using a tungsten-coated atomic force microscopy cantilever. The tip-surface chemical force distribution was reproduced from the frequency shift data using calculations based on Sader's formula. The total harmonic bonding stiffness between the dimer atoms and the substrate was first discovered by fitting the Morse force to the tip-surface chemical force distribution with consideration of the relaxation in the tip-surface gap. By excluding the contribution exerted by the probe tip, we observed that the harmonic bonding compliance of the buckling-up dimer atom was 4.8 × 10(-3) m/N stiffer than that of the buckling-down dimer atom. This technique for probing the elastic bonding states of individual surface atoms at the atomic scale is unique.

Complex design of dissipation signals in non-contact atomic force microscopy.

Complex interplay between topography and dissipation signals in Non-Contact Atomic Force Microscopy (NC-AFM) is studied by a combination of state-of-the-art theory and experiment applied to the Si(001) surface prone to instabilities. Considering a wide range of tip-sample separations down to the near-contact regime and several tip models, both stiff and more flexible, a sophisticated architecture of hysteresis loops in the simulated tip force-distance curves is revealed. At small tip-surface distances the dissipation was found to be comprised of two related contributions due to both the surface and tip. These are accompanied by the corresponding surface and tip distortion approach-retraction dynamics. Qualitative conclusions drawn from the theoretical simulations such as large dissipation signals (>1.0 eV) and a step-like dissipation dependent on the tip-surface distance are broadly supported by the experimental observations. In view of the obtained results we also discuss the reproducibility of NC-AFM imaging.

Efficacy of sildenafil for Japanese patients with audio-visual sexual stimulation (AVSS) test by the RigiScan Plus.

Sildenafil is most effective in men with mild-to-moderate ED, but not severe ED in Japan. In order to evaluate the efficacy of sildenafil, we conducted the present study using the AVSS test by the RigiScan Plus. The subjects were 56 patients (age: 34-82 years, mean: 60.5 years) with ED. The IIEF5 questionnaire and the AVSS test were conducted before and after administration of sildenafil. The penile rigidity could not be measured in 19 patients. Of these 19, sildenafil was effective in 7 and not effective in 12. The 7 cases in whom sildenafil was effective were all false-negatives. The sensitivity of sildenafil was 84%, and its specificity was 100%. This study suggests that the AVSS test by RigiScan Plus can objectively evaluate the efficacy of sildenafil, and shows potential for predicting that efficacy.

Split renal function does not change after successful treatment in children with primary vesico-ureteric reflux.

OBJECTIVE: To evaluate the renal growth pattern in patients with primary vesico-ureteric reflux (VUR) using long-term measurements of split renal function with 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy. PATIENTS AND METHODS: In all, 712 children aged < 16 years (466 boys and 246 girls) with primary VUR were referred to our hospital from July 1991 to December 2000. VUR was diagnosed by voiding cysto-urethrography. The patients were treated either surgically (group 1) or conservatively (group 2) and followed with serial 99mTc-DMSA scintigraphy for up to 10 years. There were 942 examinations in 367 of 712 patients who had repeat scintigraphy. Patients with secondary VUR, VUR to a solitary or fused kidney, or upper urinary tract obstruction, were excluded. Five of 298 patients (1.7%) who had ureteric reimplantation had a febrile urinary tract infection (UTI) soon after surgery but none recurred (recurrence is an indication for surgery in children with VUR); there was no febrile UTI in the 69 patients in group 2. Planar scintigraphy with 99mTc-DMSA was used to assess the absolute uptake (AU) of each kidney, measured as a percentage of the injected dose, and the relative uptake (RU = AU of each kidney/AU of both kidneys) calculated. The initial examination was at least 4 weeks after any febrile UTI in most patients. Serial studies were conducted 1 year after surgery and then biannually in group 1. In group 2 the DMSA scan was repeated every 2-3 years. The change in split renal function was compared with the RU of the right kidney. RESULTS: The RU of the right kidney at the initial scan correlated closely with those on repeated scans in both groups. The correlation coefficients were 0.99 in group 1 and 0.94-0.97 in group 2 at every study. The change of RU remained within 0.05 in all patients after treatment. CONCLUSIONS: Under strict control of UTI, split renal function in children with primary VUR does not change. There may be no possibility of accelerated or compensatory growth of the kidney with reflux nephropathy, but no concern about deterioration and atrophy either.

A novel 5-HT3 receptor agonist, YM-31636, increases gastrointestinal motility without increasing abdominal pain.

We examined the effects of YM-31636 (2-(1H-imidazol-4-ylmethyl)-8H-indeno[1,2-d]thiazole monofumarate), a novel 5-HT3 receptor agonist, on gastrointestinal functions including visceral pain reflex in rats. Injection of YM-31636 increased the number of fecal pellets. This effect was completely inhibited by ramosetron, a 5-HT3 receptor antagonist. YM-31636 also increased the intracolonic pressure measured in both conscious and anesthetized rats. In isolated distal colon, YM-31636 increased the short-circuit current response. This effect was abolished by ramosetron. Both the maximal response and the potency of YM-31636 were weaker than those of other 5-HT3 receptor agonists. In two visceral pain reflex models, YM-31636 neither changed the magnitude of pressor response to colonic distension in anesthetized rats nor affected the visceromotor threshold to colorectal distension in conscious rats. In conclusion, YM-31636 facilitated defecation without increasing visceral pain. Consequently, 5-HT3 receptor agonists like YM-31636 would be promising in the treatment of chronic constipation.

Investigation of the effects of YM-31636, a novel 5-HT3 receptor agonist, on defecation in normal and constipated ferrets.

We examined the effects of YM-31636 (2-(1H-imidazol-4-ylmethyl)-8H-indeno[1,2-d]thiazole monofumarate), a newly synthesized 5-HT(3) receptor agonist, on defecation in normal and constipated ferrets, and evaluated it as an agent against constipation. YM-31636 facilitated defecation without inducing diarrhea or emetic episodes. This effect occurred within 1 h after oral administration, mostly within 30 min, whereas sodium picosulfate, a widely used laxative, tended to increase the frequency of defecation for several hours with much lower peak incidence than that of YM-31636, and induced diarrhea. UK14304 (brimonidine), an alpha2 receptor agonist, and morphine reduced the frequency of defecation and YM-31636 restored it. These effects of YM-31636 were antagonized by ramosetron, a 5-HT(3) receptor antagonist. These results suggest that YM-31636 could be promising in the treatment of constipation. Because of an early and reliable onset of action compared with sodium picosulfate, YM-31636 could make it easier to control the time of defecation.

Urological management of cloacal anomalies.

BACKGROUND: A cloacal anomaly results from incomplete urorectal division and is frequently associated with genitourinary abnormalities. Experience of the urological reconstruction of this entity is reported. METHODS: Nine girls with cloacal malformation have been treated at the Osaka Medical Center in the past 9 years. Seven patients were detected by prenatal ultrasonography as having: megacystis (two patients); hydronephrosis (two patients); or hydrometrocolpos (three patients). Two patients underwent prenatal shunt placement between the enlarged bladder and the amniotic space. RESULTS: For neonatal urinary diversion, four patients received cystostomy. Six of seven patients with associated hydrocolpos required intermittent catheterization to decompress an enlarged vagina. Vesicoureteral reflux was detected in 12 ureters of seven patients. Antireflux surgery was indicated in four patients before definitive repair. Definitive reconstruction was performed on eight patients. The posterior sagittal approach was used in all patients. Vaginal reconstruction was done utilizing a perineal skin flap (one patient), a tubularized vaginal flap (three patients), distal rectum (three patients) and total urogenital mobilization (one patient). Postoperatively, urethrovaginal fistula was created in one patient and complete occlusion was seen in one patient. CONCLUSION: The anatomical variety of this entity determines the management options from in utero. It involves not only the creation of three perineal orifices, but also a continent, catheterizable urethra under the stabilization of renal function. Accomplishment of the definitive repair requires the combined expertise of experienced pediatric surgeons and pediatric urologists.

Cellular membranes that undergo cyclic changes in tension: Direct measurement of force generation by an in vitro contractile vacuole of Paramecium multimicronucleatum.

The contractile vacuole of the fresh water protozoan Paramecium is a membrane-bound vesicle that expels excess cytosolic water, acquired osmotically, through its periodic exocytotic activity. The in vitro contractile vacuole, isolated in a small amount of cytosol from the Paramecium cell and confined under mineral oil, showed periodic rounding and slackening at regular intervals for an extended time. The contractile vacuole rounded against the cytosol-mineral oil boundary tension. The tension at the surface of the contractile vacuole is, therefore, assumed to increase during the rounding phase. We first estimated the tension relative to the boundary tension from the degree of compression of the contractile vacuole by the boundary. We then determined the absolute value for the tension at the surface of the contractile vacuole from the degree of bending of an elastic carbon fiber microcantilever (8 microm thick; 2 mm long), whose free end was placed at the surface of an in vitro contractile vacuole. The tension was found to increase to its maximum value of approximately 5 mN m(-)(1) when the contractile vacuole rounded. This value was more than 35 times higher than that for the slackened contractile vacuole. Electron micrographs of conventional thin sections of chemically fixed in vitro contractile vacuoles as well as those of in vivo contractile vacuoles obtained from rapid frozen and cryosubstituted cells revealed the lack of any ultrastructural evidence for the presence of a fibrous network system surrounding the contractile vacuole. Thus we conclude that the mechanism(s) by which tension is developed at the surface of the contractile vacuole membrane resides in the contractile vacuole membrane itself. We propose a hypothesis that periodic changes in the spontaneous curvature of the contractile vacuole's lipid bilayer membrane is involved in the periodic development of higher contractile vacuole membrane tension. The isolated CV promises to be an excellent model system for understanding the molecular mechanisms of the dynamics of biological membrane.

How external osmolarity affects the activity of the contractile vacuole complex, the cytosolic osmolarity and the water permeability of the plasma membrane in Paramecium multimicronucleatum.

The rate of fluid expulsion, R(CVC), from the contractile vacuole complex (CVC) of Paramecium multimicronucleatum was estimated from the volume of the contractile vacuoles (CVs) immediately before the start of fluid discharge and from the time elapsing between discharges. The R(CVC) increased when the cell was exposed to a strongly hypotonic solution and decreased in a weakly hypotonic solution. When the cell was exposed to an isotonic or a hypertonic solution, R(CVC) fell to zero. The time constant, tau, used to describe the change in R(CVC) in response to a change in external osmolarity shortened after a short-term exposure to a strongly hypotonic solution and lengthened after a short-term exposure to a less hypotonic solution. A remarkable lengthening of tau occurred after a short-term exposure to isotonic or hypertonic solution. Under natural conditions, mechanisms for controlling R(CVC) are effective in maintaining the cytosolic osmolarity hypertonic within a narrow concentration range despite changes in the external osmolarity, which is normally hypotonic to the cytosol. Cells exposed to an isotonic or hypertonic solution resumed CV activity when left in the solution for 12 h. The cytosolic osmolarity was found to increase and to remain hypertonic to the external solution. This will permit cells to continue to acquire water. The increase in the cytosolic osmolarity occurred in a stepwise fashion, rather than linearly, as the external osmolarity increased. That is, the cytosolic osmolarity first remained more-or-less constant at an increased level until the external osmolarity exceeded this level. Thereupon, the cytosolic osmolarity increased to a new higher level in 12 h, so that the cytosol again became hypertonic to the external solution and the cells resumed CV activity. These results imply that the cell needs to maintain water segregation activity even after it has been exposed to an isotonic or hypertonic environment. This supports the idea that the CVC might be involved not only in the elimination of excess cytosolic water but also in the excretion of some metabolic waste substances.

Simultaneous STM and UHV electron microscope observation of silicon nanowires extracted from Si(111) surface

A miniaturized scanning tunnelling microscope (STM) was fitted in a side-entry holder of an ultra-high vacuum electron microscope. The clean Si(111)7 x 7 surface was observed by both STM and reflection electron microscopy (REM) at atomic resolution. The tungsten tips were often rounded off upon tip-approach with a constant current, through a gentle touch with the sample surface. The apices of such rounded tips had radii of several tens of granometre with widths of about 3 x 3 nm. Atomically resolved STM of the Si(111)7 x 7 surface was obtainable when an atom or an atomic cluster sits on the tip surface. The rounded tips were used for fabrication of Si nanowires by the touch-and-away operation of the tip. The nanowires grew longer at higher substrate temperature and they reached as long as several tens of nanometre at 700 degrees C. The nanowire had many twins and the (111) twin lamellae were stacked in the direction of the wire axis. In another case, the twin planes were oblique to the wire axis so that the (112) direction was nearly parallel to the wire axis.

Pharmacological profile of YM-31636, a novel 5-HT3 receptor agonist, in vitro.

We investigated the in vitro pharmacological profile of YM-31636 (2-(1H-imidazol-4-ylmethyl)-8H-indeno[1,2-d]thiazole monofumarate). In cloned human 5-HT3A receptors, YM-31636 had a pKi value of 9.67 vs. ramosetron and pKi values for other 5-HT3 receptor agonists were less than 7. YM-31636 showed very low affinities for other receptors. YM-31636 induced contraction of isolated guinea pig distal colon. The intrinsic activity was approximately 0.90 compared with 5-hydroxytryptamine's (5-HT) 1.0, and the potency was 26 times greater than that of 5-HT. YM-31636 increased short-circuit current (Isc) in the isolated guinea pig distal colon. In this case, the relative intrinsic activity was approximately 0.19. In isolated guinea pig right atrium, YM-31636 induced tachycardia with the relative intrinsic activity of approximately 0.23. All these effects of YM-31636 were antagonized by ramosetron, a selective 5-HT3 receptor antagonist. These results suggest that YM-31636 is a potent and selective 5-HT3 receptor agonist, preferentially acting on the contraction of the colon.

Transpapillary biopsy in gallbladder disease.

BACKGROUND: Endoscopic biopsy is routine in gastrointestinal disease; similarly, histopathologic diagnosis is desirable in gallbladder disease. In this study we examined the clinical usefulness and the problems associated with transpapillary gallbladder biopsy. METHODS: Transpapillary gallbladder biopsy was attempted in 9 patients with gallbladder disease. After inserting a catheter sheath into the gallbladder using a guidewire via the transpapillary route without sphincterotomy, we inserted a biopsy forceps into the lumen of the sheath up to the gallbladder lumen and obtained specimens. RESULTS: We could obtain sufficient specimens for histopathologic diagnosis in 8 of 9 cases (88.9%). Of the 8 successful cases, targeted specimens were obtained in 7 (87.5%). Diagnostic accuracy with respect to malignant versus benign disease was 100% (2 of 2) and 83.3% (5 of 6), respectively. There were no complications. CONCLUSION: Transpapillary gallbladder biopsy is a clinically useful technique because it facilitates histopathologic diagnosis and therefore guides the choice of therapy.

Periodic tension development in the membrane of the in vitro contractile vacuole of Paramecium multimicronucleatum: modification by bisection, fusion and suction.

The contractile vacuole of the freshwater protozoan Paramecium multimicronucleatum is a membrane-bound exocytotic vesicle that expels excess cytosolic water. The in vitro contractile vacuole isolated from P. multimicronucleatum along with a small amount of cytosol and confined under mineral oil showed periodic rounding and slackening at fairly regular intervals. Activity lasted for over 30 min at room temperature (24-27 degrees C). The rounding of the in vitro contractile vacuole corresponded to the increased membrane tension of the in vivo contractile vacuole that occurs immediately before fluid expulsion. Unlike the in vivo contractile vacuole, the in vitro contractile vacuole did not expel fluid, since it lacked a mechanism to form a pore. The subsequent slackening of the in vitro contractile vacuole corresponded to the fluid-filling phase of the in vivo contractile vacuole that occurs at decreased membrane tension. Fluid filling occurred in the in vitro contractile vacuole only when it was isolated together with its radial arms. In vitro membrane-bound vesicles obtained by 'bisecting' (although the two parts were not always identical in size) an in vitro contractile vacuole established their own independent rounding-slackening cycles. In vitro contractile vacuole vesicles could fuse again when the vesicles slackened. The fused vesicle then showed a rounding-slackening cycle with a period closer to that of the vesicle that exhibited the shorter cycle period. An additional rounding phase of the in vitro contractile vacuole could be induced by applying suction to a portion of its membrane with a micropipette when the contractile vacuole was in its slackened phase. This suggests that maximum tension development in the contractile vacuole membrane can be triggered when tension is increased in any part of the contractile vacuole membrane. The time from the start of an extra rounding phase to the next spontaneous rounding and for subsequent rounding-slackening cycles was nearly the same as that before the extra rounding phase. This implies that there is no master pacemaker to control the rounding-slackening cycle in the contractile vacuole membrane. Severed radial arms also became vesiculated and, like contractile vacuole membranes, these in vitro vesicles showed independent rounding-slackening cycles and vesicle-vesicle fusions. Thus, membrane derived from the radial arm seems to be identical in its tension-developing properties with the contractile vacuole membrane. ATP was found to be required for contractile vacuole rounding but inhibitors of actin or tubulin polymerization, such as cytochalasin B and Nocodazole, had no effect on the in vitro contractile vacuole's rounding-slackening cycle.

An evaluation of three-dimensional ultrasonography for the measurement of gallbladder volume.

OBJECTIVE: Various three-dimensional ultrasonography systems have been developed. We estimated the accuracy of a three-dimensional ultrasonography system for measuring gallbladder volume and compared the results to the sum-of-cylinders method. METHODS: In an in vitro study, 10 balloons of various shapes, sized 5-68 mL were scanned by real-time ultrasonography. In an in vivo study, we evaluated the gallbladder emptying of 14 healthy male volunteers after ingestion of two raw egg yolks. In both studies, volume measurement was performed by the three-dimensional ultrasonography method and the sum-of-cylinders method. RESULTS: With the three-dimensional ultrasonography method, the mean difference between the measured volume and the true volume and the limits of agreement were smaller than those of the sum-of-cylinders method. Gallbladder volumes did not differ significantly with both ultrasound methods. CONCLUSION: The three-dimensional ultrasonography method accurately determined gallbladder volumes.

A key function of non-planar membranes and their associated microtubular ribbons in contractile vacuole membrane dynamics is revealed by electrophysiologically controlled fixation of Paramecium.

The contractile vacuole complex of the fresh water protozoan Paramecium multimicronucleatum exhibits periodic exocytotic activity. This keeps cytosolic osmolarity at a constant value. The contractile vacuole, the central exocytotic vesicle of the complex, becomes disconnected from its surrounding radial arms and rounds before its fluid content is expelled. We previously proposed a hypothesis that the rounding of the contractile vacuole corresponds to an increase in its membrane tension and that a periodic increase in membrane tension governs the exocytotic cycle. We also proposed a hypothesis that transformation of excess planar membrane of the contractile vacuole into 40 nm diameter tubules, that remain continuous with the contractile vacuole membrane, is a primary cause for the tension development in the planar membrane. In order to investigate tension development further, we have examined electron microscopically the contractile vacuole membrane at the rounding phase. To do this, we developed a computer-aided system to fix the cell precisely at the time that the contractile vacuole exhibited rounding. In this system a decrease in the electrical potential across the contractile vacuole membrane that accompanied the vacuole's rounding was monitored through a fine-tipped microelectrode inserted directly into the in vivo contractile vacuole. A decrease in membrane potential was used to generate an electric signal that activated an injector for injecting a fixative through a microcapillary against the cell at the precise time of rounding. Subsequent electron micrographs of the contractile vacuole membrane clearly demonstrated that numerous approximately 40 nm membrane-bound tubules formed in the vicinity of the vacuole's microtubule ribbons when the vacuole showed rounding. This finding suggested that membrane tubulation was the cause for topographical isolation of excess membrane from the planar membrane during the periodic rounding of the contractile vacuole. This together with stereo-pair images of the contractile vacuole complex membranes suggested that the microtubule ribbons were intimately involved in enhancing this membrane tubulation activity. Electron micrographs of the contractile vacuole complexes also showed that decorated tubules came to lie abnormally close to the contractile vacuole in these impaled cells. This suggested that the contractile vacuole was capable of utilizing the smooth spongiome membrane that lies around the ampullae and the collecting canals to increase its size.

A study to determine if basic fibroblast growth factor (bFGF) reduces myocardial infarct size in acute coronary arterial occlusion.

We investigated the angiogenic and myocardial salvage effects of bFGF. Twelve beagles with ligated left anterior descending coronary arteries were divided into two groups: a FGF group administered bFGF intravenously, and a Control group, after CAG immediately post-ligation. One week post-ligation, CAG was repeated. The heart was sliced along the short axis. For each section, the fluorescein Na staining deficit area (DA) and ratio of DA to total area (DAR), TTC staining of the infarct area (IA) and ratio of IA to total area (IAR), and Masson trichrome staining of the fibrosed area (MA) and ratio of MA to total area (MAR), were calculated. The increase in the number of collateral vessels, seen on CAG from post-ligation to 1 week later, was significantly greater in the FGF group. No significant differences in IAR or MAR were seen between the groups. However, DAR and DA/IA were significantly less in the FGF group. In conclusion, bFGF had no effect on infarct size, but stimulated the growth of collateral vessels and improved coronary blood flow in IA.

[Usefulness of DIC-CT in choledocholithiasis].

In order to assess the efficacy of helical CT in drip-infusion cholangiography (DIC-CT) for diagnosis of choledocholithiasis, 82 patients with biliary diseases, including 25 patients with a definite diagnosis of choledocholithiasis obtained by direct cholangiography, were investigated by DIC-CT and EUS. Comparative investigation showed that, of the 25 cases, 94.7% could be imaged by DIC-CT and 87.5% by EUS, with respective sensitivities of 94.7% and 87.5%. The specificities in both cases were 100% and accuracies were 97.8% with DIC-CT and 96% with EUS respectively. Therefore, in diagnosis the choledocholithiasis, DIC-CT displays similar diagnostic efficiency as EUS or ERC, and can be recognized as the non-invasive and useful procedure for pre-operative diagnosis of cholecystolithiasis.