Endoscopic submucosal dissection for superficial esophageal neoplasms using the stag beetle knife

Endoscopic submucosal dissection (ESD) is an accepted standard treatment for early gastric cancer but is not widely used in the esophagus because of technical difficulties. To increase the safety of esophageal ESD, we used a scissors-type device called the stag beetle (SB) knife. The aim of this study was to determine the efficacy and safety of ESD using the SB knife. We performed a single-center retrospective, uncontrolled trial. A total of 38 lesions were excised by ESD from 35 consecutive patients who were retrospectively divided into the following two groups according to the type of knife used to perform ESD: the hook knife (hook group) was used in 20 patients (21 lesions), and the SB knife (SB group) was used in 15 patients (17 lesions). We evaluated and compared the operative time, lesion size, en bloc resection rate, pathological margins free rate, and complication rate in both groups. The operative time was shorter in the SB group (median 70.0 minutes [interquartile range, 47.5-87.0]) than in the hook group (92.0 minutes [interquartile range, 63.0-114.0]) (P = 0.019), and the rate of complications in the SB group was 0% compared with 45.0% in the hook group (P = 0.004). However, the lesion size, en bloc resection rate, and pathological margins free rate did not differ significantly between the two groups. In conclusion, ESD using the SB knife was safer than that using a conventional knife for superficial esophageal neoplasms.

The modified glucose clearance test: a novel non-invasive method for differentiating non-erosive reflux disease and erosive oesophagitis

BACKGROUND

Impaired salivary secretion has been reported to cause abnormal acid clearance from the oesophagus in gastro-oesophageal reflux disease (GERD). However, few studies have explained the differences between non-erosive reflux disease (NERD) and erosive oesophagitis (EO) with respect to salivary secretion. Aim To elucidate these differences, we measured salivary secretion by using the modified glucose clearance test (mGCT).

METHODS

All subjects completed endoscopic examinations, the frequency scale for the symptoms of GERD questionnaire and the mGCT comprising a resting GCT (measured as RGC time) and a chewing-stimulated GCT (SGC time).

RESULTS

Resting glucose clearance time was 18.5 min in control group and significantly longer in NERD and EO groups (28.5 and 39.0 min respectively). SGC time was 6.1 min in control group and 7.2 min in NERD group and significantly longer in EO group (10.2 min) than in the control and NERD groups.

CONCLUSIONS

In the EO group, both resting and stimulated salivary secretions were less than in control group. However, in the NERD group, resting salivary secretion was decreased, but stimulated salivary secretion was similar to that of the control group. Therefore, these results may help in explaining the differences in the pathogenesis of NERD and EO.

Low stray ELF magnetic field exposure system for in vitro study

An exposure facility for wide application to cell exposure to an ELF (extremely low frequency) magnetic field was developed. It is suitable for conducting experiments under a high-intensity, variable-frequency magnetic field, on the biological effects of the ELF magnetic field in an in vitro study. The exposure system consists of Merritt's 4-square coil as a basic component to generate the required magnetic field intensity of 10 mT at 50 Hz with spatial field uniformity less than +/-3% in a 400 mm cube. Concentric compensation coils are adopted to eliminate the effects of stray fields on sham (control) samples in the vicinity of the exposure system. The uniformity of the magnetic field in the exposure coil, the increase in the power supply capacity due to the existence of compensation coils, and the stray field estimation were investigated carefully. After fabricating the system, performance tests were carried out and all the characteristics were found to be satisfactory. In addition, the ideal configuration for a concentric coil system was proposed.

Experimental study on bacterial colonization of fibrin glue and its prevention

To assess the possibility of bacterial colonization of fibrin glue and the effects of adding local sustained-release antibiotics, we conducted in vivo and in vitro preliminary studies. The in vitro experiments revealed that, although there was no colonization of the fibrin glue plates by the eight strains of bacteria tested, the fibrin mesh can serve as a culture medium when blood mingles with it, as is the case in clinical use. Adding dibekacin sulfate (DKB; 3570 micrograms/mL) to fibrin glue decreased the likelihood of colonization of the fibrin mesh. The pharmacokinetics of the added DKB were investigated by adding DKB-supplemented fibrin glue directly to muscle and vascular tissue in male rats. The DKB rapidly eluded from the fibrin glue (less than 0.2% remained after 24 hours). Because the amount remaining after 7 days (2.03 micrograms/mL) was greater than the minimum inhibitory concentration for most clinical pathogens, a 7-day preventive effect against colonization of the fibrin glue and the surrounding tissue can be anticipated at the concentration used in the present experiments. Experiments using the dermis layer of porcine skin strips showed that the added DKB did not affect the adhesive strength of the fibrin glue.

In vivo adaptative regulation of muscarinic receptors and muscarinic stimulation-induced Ca2+ mobilization during short-term heat exposure in rat parotid glands

1. Adaptation of muscarinic receptors (MR)--muscarinic stimulation--induced intracellular Ca2+ mobilization during short-heat exposure (33 degrees C). 2. Heat-exposure for 48 hr decreased the carbachol (CCh)-stimulated cytosolic Ca2+ concentration increase. 3. The number of MR on cell surface increased transiently at 24 hr with a subsequent decrease at 48 hr. 4. CCh-stimulated inositol triphosphate (IP3) formation decreased at 48 hr. 5. In saponin-permeabilized cells, 1,4,5-IP3-induced 45Ca2+ release decreased at 24 hr. 6. The data suggest that the adaptation for increased muscarinic stimulation occurs at IP3 generating sites as well as at intracellular IP3 receptor sites during heat exposure.

Intralysosomal pH and release of lysosomal enzymes in the rat liver after exhaustive exercise

The mechanism underlying exhaustive exercise-induced release of lysosomal enzymes was studied in the rat liver. Exhaustive exercise resulted in the release of beta-glucuronidase and cathepsin D, but not beta-glucosidase and acid phosphatase, into the blood and cytosol, suggesting that the release of lysosomal enzymes is not due to disruption of lysosomal membranes. The intralysosomal pH of the liver, which was approximately 5.5 at the resting level, rose significantly after exhaustive exercise to pH 6.3. In vitro, beta-glucuronidase and cathepsin D were released at an intralysosomal pH exceeding 6.2. In contrast, beta-glucosidase and acid phosphatase were not released. The elevation of intralysosomal pH reduced the aggregation of beta-glucuronidase and cathepsin D. The rate of ammonia accumulation increased markedly in the lysosome-enriched subcellular fraction after exercise. There was a positive relationship between the rate of ammonia accumulation and the elevation of intralysosomal pH in vitro. Lysosomes isolated after exhaustive exercise showed significantly increased osmotic fragility. Our findings suggest that, during exhaustive exercise, the accumulation of ammonia in lysosomes leads to the elevation of intralysosomal pH, resulting in the reduced aggregation of certain lysosomal enzymes. Thus, less aggregated lysosomal enzymes may be released into the cytosol through the lysosomal membrane, the permeability of which has been increased.

Recovery of beta-receptors and adenylate cyclase from desensitization induced by short term heat exposure in rat parotid glands

1. The recovery of rat parotid beta-adrenergic receptors (beta-AR) and adenylate cyclase (AC) from heat (33 degrees C)-induced desensitization was studied. 2. Down-regulated cell surface beta-AR and AC activity in response to isoprenaline (IPR) returned to the control level 120 hr after the termination of heat exposure. 3. However, beta-AR in parotid crude membranes increased over the control level for 48-120 hr. 4. Coupling between beta-AR and G protein(s) was attenuated at 120 hr. 5. These data suggest that beta-AR on the cell surface, but not those internalized, can transduce biological responses.

Mechanism of carbachol-stimulated diacylglycerol formation in rat parotid acinar cells

We studied the relationship between phosphoinositide hydrolysis, phosphatidylcholine hydrolysis, and sn-1,2-diacylglycerol (DAG) formation in response to carbachol stimulation in rat parotid acinar cells. Previously, we demonstrated that DAG formation stimulated with 1 microM carbachol was biphasic: the first peak occurred at 5 min and the second one at 20 min. It was also demonstrated that the second peak was regulated in part by a calmodulin/protein kinase C-dependent mechanism. Based on the kinetic analysis of DAG formation and [32P]phosphoinositide breakdown, the first peak of carbachol (1 microM)-stimulated DAG accumulation was found to be related to the breakdown of [32P]phosphatidylinositol 4-monophosphate ([32P]PIP) and [32P]phosphatidylinositol 4,5-bisphosphate ([32P]PIP2). The second peak was found to be related to [32P]PIP2 breakdown. Carbachol stimulated the release of [3H]phosphocholine into the medium, indicating that the predominant pathway for phosphatidylcholine hydrolysis was via phospholipase C. Moreover, carbachol stimulated the release of [3H]choline metabolites in a time- and dose-dependent manner. This agonist slightly stimulated the release of [3H]ethanolamine metabolites. A calmodulin/protein kinase C-dependent mechanism was also studied and was found to be involved in carbachol-stimulated phosphatidylcholine hydrolysis; W-7, a calmodulin inhibitor and staurosporine, a protein kinase C inhibitor, inhibited the carbachol (1-microM)-induced release of [3H]choline metabolites at 20 min in a dose-dependent manner, but did not have inhibitory effects at 5 min. These results suggest that the first peak of DAG accumulation induced by carbachol is predominantly associated with the breakdown [32P]PIP and of [32P]PIP2 and that the second peak is predominantly associated with [32P]PIP2 breakdown and phosphatidylcholine hydrolysis.

In vivo adaptive control of beta-receptors and adenylate cyclase during short-term heat exposure in rat parotid glands

1. Adaptation of beta-adrenergic receptors (beta-AR) and adenylate cyclase (AC) in rat parotid glands during short-term heat exposure (33 degrees C) were studied. 2. Heat exposure reduced AC activity in response to isoproterenol (IPR). 3. The number of beta-AR on the cell surface significantly increased after 24 hr but returned to control level after 48 hr. 4. IPR-induced [3H]GDP release was significantly reduced throughout exposure. 5. The data suggest that the major factor which results in the desensitization of AC during short-term heat exposure is a blunted coupling between beta-AR and GTP binding protein(s).

Time-related changes in the distribution of 45Ca in the developing enamel of rat incisors as revealed by radioautography

The distribution and movement of calcium through the enamel organ and into the forming enamel was examined by means of quantitative 45Ca radioautography in rat incisors. Dislocation of radiocalcium in the specimen was minimized during histologic and radioautographic processing by using rapid freeze/freeze-substitution and dry emulsion coating methods. At 30 sec. after the 45Ca injection, distinct peaks of radioactivity occurred in the connective tissue immediately adjacent to the enamel organ and the infranuclear compartment of secretory ameloblasts. An intense labeling also occurred in the superficial layers of the forming enamel extending 15 microns below the surface. The grain density in the distal cytoplasm of secretory ameloblasts increased at later time periods, whereas all other regions of the enamel organ showed a considerable decrease in radioactivity. The radioactivity in the infranuclear compartment of ameloblasts with numerous mitochondria remained relatively high at 2 min. but was abolished by 10 min. after the injection. The grain density in the enamel matrix became much stronger but the labeled regions only extended to 20, 30, and 40 microns below the surface at 2, 10, and 60 min. after the injection, respectively. The application of wet emulsion over similarly prepared sections caused a severe dislocation of radiocalcium in the specimens. These data confirmed the rapid penetration of systemically administered radiocalcium into the surface layers of forming enamel and its slow diffusion to the deeper layers. The time-related changes in relative grain densities at various regions of the ameloblasts support the coexistence of a relatively slow transcellular pathway for calcium through the secretory ameloblast layer.