Shear Performance of RC Beams Reinforced with Fe-Based Shape Memory Alloy Stirrups.

In this study, the shear performance of a reinforced concrete (RC) beam with Fe-based shape memory alloy (Fe-SMA) stirrups was evaluated experimentally and analytically. Five specimens that had a possibility of shear failure under four-point loading were prepared. The major experimental variables were the spacings (300 and 200 mm) between the Fe-SMA stirrups and whether the stirrups were activated or non-activated. The shear strength of the specimen reinforced with the Fe-SMA stirrups at a spacing of 200 mm was 27.1% higher than that of the specimen reinforced at a spacing of 300 mm. The activation of the Fe-SMA stirrups, which produced active confining pressure, increased the shear strength by up to 7.6% and decreased the number of shear cracks compared to the case of the non-activated specimen. Therefore, the use of Fe-SMA stirrups could significantly improve the usability of concrete members by increasing their shear strength and initial stiffness and by controlling crack formation. Furthermore, finite element method (FEM) analysis was conducted using LS-DYNA, a commercial software program, to predict the shear performance of the RC beam reinforced with the Fe-SMA stirrups. The ultimate load and displacement of each specimen were predicted with errors less than 1.4 and 9.4%, respectively. Furthermore, the FEM predicted the change in failure mode and the stiffness improvement due to the activation of the Fe-SMA stirrups. Therefore, the proposed finite element analysis model can effectively predict the behavior of an RC beam reinforced with Fe-SMA stirrups.

[The development of irritable bowel syndrome after Shigella infection: 3 year follow-up study].

BACKGROUND/AIMS: Bacterial gastroenteritis seems to be a risk factor of irritable bowel syndrome (IBS). The incidence of post-infectious IBS (PI-IBS) was reported to be in the range of 7-31%, but few studies have reported long term follow-up results. So, we investigated the clinical course and prognosis of PI-IBS three years after shigella infection. METHODS: The subjects were recruited from our previous study, in which we investigated the incidence and risk factors of PI-IBS. We had a questionnaire based on interview with 120 controls and 124 patients who had shigella infection three years ago. Both groups were evaluated for the presence of IBS, functional bowel disorders (FBD) except IBS before, one and three years after the infection, respectively. RESULTS: Ninety-five patients (76.6%) and 105 controls (87.5%) completed the questionnaire. In patients group, 7 cases had IBS prior to infection (previous IBS), 12 cases (13.8%) had IBS after 1 year (PI-IBS). Four cases developed IBS newly after 3 years (new IBS). Thirteen cases (14.9%) in patients and 4 cases (4.5%) in controls had IBS over 3 years (OR 3.93: 1.20-12.86). The recovery rate over 3 years were 50.0% (2/4) in previous IBS and 25% (3/12) in PI-IBS. The incidence of PI-IBS after 3 years in previous FBD subjects was 28.6% and was 10.6% in normals (p<0.05). The female gender was a risk factor for FBD. CONCLUSIONS: Bacterial gastroenteritis is a trigger factor of IBS. About a quarter of PI-IBS patients are recovered over 3 years. Previous FBD except IBS is a risk factor after 3 years.

Acute hemodynamic effects of octreotide and terlipressin in patients with cirrhosis: a randomized comparison.

BACKGROUND: Octreotide and terlipressin are widely used in acute variceal hemorrhage to reduce the bleeding rate. They purportedly act by mesenteric arterial vasoconstriction, thus reducing portal venous flow (PVF) and portal pressure. Little is known about the immediate-early hemodynamic effects of these drugs. AIM: To compare the acute hemodynamic effects of octreotide and terlipressin in patients with cirrhosis. PATIENTS: Forty-two cirrhotic patients with a history of variceal bleeding were randomized to receive either octreotide 100 microg intravenous bolus followed by a continuous infusion at 250 microg/h (n = 21), or terlipressin 2 mg intravenous bolus (n = 21). METHODS: Mean arterial pressure (MAP), heart rate (HR), hepatic venous pressure gradient (HVPG), and PVF, assessed by duplex Doppler ultrasonography, were measured before and at 1, 5, 10, 15, 20, and 25 min after the start of drug administration. RESULTS: Octreotide markedly decreased HVPG (-44.5 +/- 17.8%) and PVF (-30.6 +/- 13.6%) compared to the baseline at 1 min (p < 0.05). Thereafter, both variables rapidly returned toward the baseline, and by 5 min, no significant differences in HVPG (-7.1 +/- 28.9%) and PVF (10.2 +/- 26.2%) were noted. A similar transient effect on MAP and HR was observed. Terlipressin significantly decreased HVPG (-18.3 +/- 11.9%) and PVF (-32.6 +/- 10.5%) at 1 min (p < 0.05) and sustained these effects at all time points. The effects on arterial pressure and HR were also sustained. CONCLUSIONS: Octreotide only transiently reduced portal pressure and flow, whereas the effects of terlipressin were sustained. These results suggest that terlipressin may have more sustained hemodynamic effects in patients with bleeding varices.

Relationship of hemodynamic indices and prognosis in patients with liver cirrhosis.

BACKGROUND: Hyperdynamic circulation due to reduced peripheral vascular resistance and increased cardiac output, and the development of portal hypertension are the hemodynamic changes observed in patients with liver cirrhosis. Such hemodynamic abnormalities appear in patients with late stage liver cirrhosis. Therefore, hemodynamic indices, which represent hyperdynamic circulation and portal hypertension, are significant for the prognosis of patients with liver cirrhosis. The aim of this study was to determine the hemodynamic indices associated with the prognosis of patients with liver cirrhosis. METHODS: A total of 103 patients diagnosed with liver cirrhosis between December 1999 and June 2003, with a mean follow-up period of 73 weeks, ranging from 7 to 168 weeks, were recruited. Using Child-Pugh classification, the mean arterial pressure, heart rate and hepatic venous pressure gradient (HVPG) were measured. The indices of Doppler ultrasonography, including the portal and splenic venous flows, and the resistance of the hepatic, splenic, and renal arteries were also measured using the arterial pulsatility index (PI). The prognostic values of these indices were determined by their comparison with the patient survivals. RESULTS: Significant hemodynamic indices for a bad prognosis were high HVPG (> or = 15 mmHg) and renal arterial PI (> or = 1.14)(p<0.05). A Child-Pugh score > or = 10 was important for a poor prognosis (p<0.05). CONCLUSION: Severe portal hypertension (HVPG > or = 15 mmHg) and high renal arterial resistance (PI +/- 1.14) were valuable hemodynamic indices for the prognosis of patients with liver cirrhosis. Therefore, it was concluded that the measurement of these hemodynamic indices, in addition to the Child-Pugh classification, is helpful in the prognosis of patients with liver cirrhosis.

[Usefulness of urinary trypsinogen-2 dipstick test for diagnosis of acute pancreatitis].

BACKGROUND/AIMS: The clinical usefulness of urinary trypsinogen-2 dipstick test is still in controversy. We evaluated the usefulness of urinary trypsinogen-2 dipstick test in patients with acute pancreatitis. METHODS: Urinary trypsinogen-2 dipstick test was prospectively performed in 50 patients with acute pancreatitis, 50 patients with non-pancreatic abdominal pain, and 50 healthy controls. RESULTS: On admission, urinary trypsinogen-2 dipstick test was positive in 36 of 50 patients with acute pancreatitis (sensitivity, 72%) and in 4 of 50 patients with non-pancreatic abdominal pain (specificity, 92%). On the other hand, it was all negative in controls. The sensitivity and specificity of serum lipase were 78% and 94%, respectively. At 24 hours after admission, the positive rate of urinary trypsinogen-2 dipstick test rose from 72% to 94% (p=0.02). The results of urinary trypsinogen-2 dipstick test was positive in 14 of 15 patients with severe pancreatitis and 22 of 35 patients with mild pancreatitis according to the criteria by Atlanta International Symposium, 1992. CONCLUSIONS: Urinary trypsinogen-2 dipstick test is comparable to serum lipase in diagnosing acute pancreatitis. Delayed measurement and severe pancreatitis are more likely to yield positive results with urinary trypsinogen-2 dipstick test. Thus, we suggest that the cut-off value of urinary trypsinogen-2 dipstick test should be lowered to increase its sensitivity.

[Type of electric currents used for standard endoscopic sphincterotomy does not determine the type of complications].

BACKGROUND/AIMS: The blended current is usually used for endoscopic sphincterotomy (EST) to minimize bleeding. The pure cutting current may induce less edema of the ampulla and therefore result in less injury to the pancreas theoretically. The aim of this study was to evaluate effects of electric currents used on the development of serum pancreatic enzyme evaluation, clinical pancreatitis or bleeding after EST. METHODS: One hundred and eighteen consecutive patients who underwent EST with standard papillotome alone for the treatment of choledocholithiasis were reviewed. All EST had been performed by two endoscopists whose experience on EST was similar: one uses 'blended current' (BC group, n=74), while the other uses 'pure cutting current' (PC group, n=44). RESULTS: Baseline clinical, laboratory, and procedural parameters were similar in both groups. The incidences of hyperamylasemia and hyperlipasemia were similar between two groups. There was no significant difference in the incidence of clinical pancreatitis between two groups (BC 6.8% vs PC 0.0%, p=0.1557). All episodes of pancreatitis were mild. No episodes of significant bleeding occurred after EST. The incidences of sepsis, cholangitis and perforation were also not different between two groups. CONCLUSIONS: Development of complications after standard EST such as hyperamylasemia, clinical pancreatitis, and bleeding may not depend on the electric current used.

Effects of tegaserod on ileal peristalsis of guinea pig in vitro.

The mechanisms of prokinetic action of tegaserod in the gastrointestinal tract has not been studied in detail. The aim of this study was to investigate the effect of tegaserod on peristaltic reflexes and propagating peristaltic waves in guinea pig ileum. A partitioned organ bath divided into three chambers was used to investigate the effect of tegaserod on peristaltic reflexes. A sensory stimulus was applied to the intermediate chamber, and changes in the circular muscle tension were monitored in a peripheral chamber. Another peristaltic bath was used to investigate the effect of tegaserod on peristaltic waves induced by intraluminal perfusion. Guinea pig ileum exhibited contractions in the circular muscle both orally and anally in response to mucosal stroking. Tegaserod (10(-8) - 10(-6) M) did not influence the maximal amplitude and the area under the curve of contraction both orally and anally to a mucosal stimulus. Intraluminal perfusion of fluid containing tegaserod (10(-8) - 10(-6) M) significantly increased the number of peristaltic waves in a concentration-dependent manner (P<0.05). Also, tegaserod (10(-8) - 10(-6) M) significantly increased the area under the curve of peristaltic waves (P<0.05). It is concluded that tegaserod has prokinetic action on guinea pig ileum by increasing the number of the circular muscle contractions during peristalsis.

[Altered colonic transit in TNBS-induced experimental colitis in guinea pig and distribution of nitric oxide synthase in the colonic wall].

BACKGROUND/AIMS: Inflammation-induced alterations in smooth muscle contractility may be due to the effects on smooth muscle itself, neurotransmitters or enteric nerves. In dextran sulfate sodium-induced colitic rat, the delay in colonic transit was caused by decreased activity and production of neuronal nitric oxide synthase (nNOS) in the myenteric plexus of the distal colon. The aim of this study was to investigate the relationship between the delay in colonic transit and the distribution of inducible NOS (iNOS) and nNOS immunoreactive cells in the myenteric plexus of trinitrobenzene sulfonic acid (TNBS)-induced colitic guinea pig. METHODS: Sacrificed and their colonic tissues of forty-five TNBS-induced colitic guinea pigs were used to measure the colonic transit, and analyzed by immunohistochemistry. RESULTS: Colonic transit was delayed significantly at 3, 7 and 14 days after administration of TNBS. In control, nNOS immunoreactivity was present in the mucosa, submucosa, lamina propria, and ganglion cells of the myenteric plexus, while after TNBS treatment, reduced nNOS cells were found. However, the number of nNOS ganglion cells in the myenteric plexus was similar to those seen in controls. After administration of TNBS, iNOS immunoreactivity was increased in the mucosa and submucosa, but the number of iNOS positive ganglion cells in the myenteric plexus was not changed compared to control. CONCLUSIONS: It is suggested that in TNBS-induced guinea pig colitis, delayed colonic transit is not associated with the expression of nNOS nor iNOS in the myenteric plexus.

Investigation into the effects of mosapride on motility of Guinea pig stomach, ileum, and colon.

Mosapride citrate (Mosapride) is a new prokinetic agent that enhances the gastrointestinal (GI) motility by stimulation of 5-HT4 receptors. This agent stimulates acetylcholine release from enteric cholinergic neurons in the GI wall. It was reported in several studies that mosapride selectively enhanced the upper, but not lower, GI motor activity. However, in these studies other 5-HT4 receptor agonists exerted stimulating effects on the motility of the colon. Moreover, it is well known that the receptors of 5-HT4 are also located in the colon. The purpose of this study was to estimate the effect of mosapride on the motility of the stomach, ileum and colon in the guinea pig and to investigate whether or not mosapride influenced the colonic motility. Mosapride significantly increased the amplitude of the contraction waves in the guinea pig stomach by electrical stimulation. In addition, it significantly increased the number of peaks, the area under the curve and the propagation velocity of the peristaltic contraction of the guinea pig ileum in a concentration dependent fashion. Mosapride also significantly shortened the transit time of the guinea pig colon. Accordingly, we concluded that mosapride exerted prokinetic effect on the entire GI tract of the guinea pig. Based on the possibility of similar results in humans, we suggest the potential use of mosapride for lower GI motor disorders such as constipation and upper GI motor disorders such as gastroesophageal reflex disease or gastroparesis.