20-MHz phased array ultrasound transducer for in vivo ultrasound imaging of small animals.

In vivo ultrasound imaging with phased array transducers is of great importance for both clinical application and biomedical research. In this work, relaxor ferroelectric PMN-0.28PT single crystal with very high piezoelectric constant d33 ≥ 2000 pC/N and electromechanical coupling coefficient k33 âˆ¼ 0.92 is used to fabricate high-frequency phased array transducers. A 128-element 20-MHz phased array transducer is successfully fabricated, and the optimized performance of -6 dB average bandwidth of âˆ¼ 84 % and insertion loss of -43 dB are achieved. The axial and lateral imaging resolutions of the transducer are determined to be 81 µm and 243 µm, respectively. With Verasonics image platform, in vivo fisheye images are acquired, demonstrating the potential application of our developed high-frequency phased array transducer for biomedical research on small animals.

[The role of nitric oxide in the inhibitory effects of exogenous hydrogen sulfide on rat colonic smooth muscle contraction].

Objective: To investigate the role of nitric oxide (NO) in hydrogen sulfide (H(2)S)-induced inhibition upon colonic smooth muscle contraction. Methods: Immunohistochemistry was applied to observe the distribution of H(2)S-producing enzymes CBS and CSE in adult male Wistar rats. Organ bath system was used to observe the spontaneous contraction of colonic smooth muscle. Patch clamp technique was applied to record currents of L-type calcium channel (I(Ca,L)) in smooth muscle cells. Results: Specific immunoreactivity for CSE and CBS was observed in mucosa, smooth muscle and enteric plexus of rat proximal colon. NaHS elicited relaxation in a concentration-dependent manner upon muscle contraction in the presence of tetrodotoxin. The NaHS IC(50) of LM was 917.6 µmol/L (95% CI: 776.3-1 085 µmol/L, n=6) and the NaHS IC(50) of CM was 730.4 µmol/L (95% CI: 592.2-900.8 µmol/L, n=6). The SNP-induced relaxation in muscle strips was partially reversed by NaHS (P<0.05). Instead, the relaxation caused by NaHS was decreased by the sGC inhibitor ODQ but affected neither by NO precursor L-arginine, the NO inhibitor L-NNA nor the competitive cGMP antagonist PET-cGMP. NaHS (100 µmol/L) increased I(Ca,L) while NaHS (300 µmol/L) decreased the peak I(Ca,L) with modifying the ion channel characteristics (P<0.05). Conclusions: Exogenous hydrogen sulfide might have a dual effect on colonic motility and its inhibitory effect might be independent of NO signaling system. L-type calcium channel may play an important role during the process of H(2)S modulating colonic contraction.

[Effect of metformin on mitochondrial pathway of apoptosis and oxidative stress in cell model of nonalcoholic fatty liver disease].

Objective: To investigate the effects of metformin on mitochondrial pathway of apoptosis and oxidative stress in cell model of nonalcoholic fatty liver disease. Methods: An in vitro cell model of nonalcoholic fatty liver disease was established using 0.6 mmol/L oleic acid to induce lipid accumulation in HepG2 cells. HepG2 cells were divided into control (Con) group, oleic acid (OA) group, and metformin-low (1mmol/L) and high (10mmol/L) dose group. Oil Red O stain was used to detect intracellular lipid droplet distribution. The levels of alanine aminotransferase and aspartate aminotransferase in the culture supernatant were detected by assay kits. DCFH-DA method was used to detect the reactive oxygen species of HepG2 cells. Double staining flow cytometry was used to detect the apoptosis rate of HepG2 cells. Western blot was used to detect caspase-3, B-lymphocyte lymphoma-related protein, B-cell lymphoma 2, and cytochrome c protein. One-way analysis of variance was used to compare the data between groups. Results: Oleic acid-induced HepG2 cells were significantly increased with lipid droplets. Low and high-dose metformin had reduced intracellular lipid droplets accumulation. The effect of metformin in the high-dose group was more significant than that in the low-dose group. Aspartate aminotransferase and alanine aminotransferase in HepG2 cells of OA group were significantly increased, which were (43.41 ± 7.11) U/L and (29.56 ± 4.11) U/L, respectively. The intracellular aspartate aminotransferase and alanine aminotransferase were decreased significantly after the treatment with low and high-dose metformin, which were (32.44 ± 4.08)U/L, (19.31 ± 3.03) U/L, (26.00 ± 3.11) U/L and (15.11 ± 4.11) U/L, respectively and the differences were statistically significant (P < 0.05). DCFH-DA test results showed that the fluorescence intensity of reactive oxygen species in the oleic acid group was 41.21% ± 4.23%, while the fluorescence intensity of reactive oxygen species in the low and high-dose metformin groups were reduced to 27.44% ± 3.91%, and 17.55% ± 5.11%, respectively and the differences between the groups were statistically significant (P < 0.05). The results of flow cytometry analysis showed that the cell apoptosis rate of the OA group was significantly higher than that of the Con group (12.12% ± 0.72% vs. 3.04% ± 0.57%, P < 0.05).The apoptosis rate of HepG2 cells was significantly reduced after metformin treatment at low and high doses (8.71% ± 0.71%, 5.71% ± 0.61%, P < 0.05). Western blot results showed that compared with the Con group, the expressions of B-lymphocyte lymphoma-related protein, cytochrome c, and caspase-3 were increased in the OA group, while the B-cell lymphoma 2 were decreased (P < 0.05). The expression of B-lymphocyte lymphoma-related protein, cytochrome c, and caspase-3 protein in HepG2 cells was decreased after treatment with low and high-dose metformin, while B-cell lymphoma 2 was increased (P < 0.05). Conclusion: Metformin can effectively alleviate steatosis and improve the HepG2 function in cell model of nonalcoholic fatty liver disease. The mechanism of metformin may be related to the reduction of oxidative stress injury, the regulation of protein expression related to mitochondrial apoptosis pathway and the inhibition of cell apoptosis.

Evodiamine inhibits gastrointestinal motility via CCK and CCK1 receptor in water-avoidence stress rat model.

AIM: Evodiamine (EVO) has been reported to play an important role in regulating gastrointestinal motility, but the evidence is insufficient, and the mechanism remains unknown. The aim of this study is to investigate the possible role of EVO in stress-induced colonic hypermotility and the potential mechanisms via both in vivo and in vitro investigations. METHODS: Male Sprague-Dawley rats were exposed to water avoidance stress (WAS) for 1 h or sham WAS daily for 10 consecutive days to construct the rat model. The colonic contractile activity was studied in an organ bath system. The serum CCK-8 level was detected using an enzyme immunoassay kit, and gastrointestinal transit was detected by intragastric administration of India ink. RESULTS: WAS induced gastrointestinal hypermotility in male rats. EVO significantly inhibited the contractile activity of colonic muscle strips; this effect was not blocked by TTX and the CCK1 receptor antagonist devazepide. Chronic WAS induced a slight but nonsignificant increase in the serum CCK-8 level, while EVO elevated the serum CCK-8 level in the WAS rats in a dose-dependent manner. Exogenous CCK-8 significantly inhibited the contractile activity of the colonic muscle strips; this effect was not blocked by TTX but was completely blocked by devazepide. Both EVO and CCK-8 inhibited gastrointestinal transit, and the effect of EVO could be partially blocked by devazepide. SIGNIFICANCE: EVO can reverse stress-induced gastrointestinal hypermotility. This effect may partially occur as a result of promoting the release of CCK and then activating the CCK1 receptor instead of directly activating the CCK1 receptor.

Role of chemokines in promoting instability of coronary atherosclerotic plaques and the underlying molecular mechanism

Our aim was to investigate the role of chemokines in promoting instability of coronary atherosclerotic plaques and the underlying molecular mechanism. Coronary angiography and intravascular ultrasound (IVUS) were performed in 60 stable angina pectoris (SAP) patients and 60 unstable angina pectoris (UAP) patients. The chemotactic activity of monocytes in the 2 groups of patients was examined in Transwell chambers. High-sensitivity C-reactive protein (hs-CRP), monocyte chemoattractant protein-1 (MCP-1), regulated on activation in normal T-cell expressed and secreted (RANTES), and fractalkine in serum were examined with ELISA kits, and expression of MCP-1, RANTES, and fractalkine mRNA was examined with real-time PCR. In the SAP group, 92 plaques were detected with IVUS. In the UAP group, 96 plaques were detected with IVUS. The plaques in the UAP group were mainly lipid 51.04% (49/96) and the plaques in the SAP group were mainly fibrous 52.17% (48/92). Compared with the SAP group, the plaque burden and vascular remodeling index in the UAP group were significantly greater than in the SAP group (P<0.01). Chemotactic activity and the number of mobile monocytes in the UAP group were significantly greater than in the SAP group (P<0.01). Concentrations of hs-CRP, MCP-1, RANTES, and fractalkine in the serum of the UAP group were significantly higher than in the serum of the SAP group (P<0.05 or P<0.01), and expression of MCP-1, RANTES, and fractalkine mRNA was significantly higher than in the SAP group (P<0.05). MCP-1, RANTES, and fractalkine probably promote instability of coronary atherosclerotic plaque.

Focused intravascular ultrasonic probe using dimpled transducer elements.

High-frequency focused intravascular ultrasonic probes were fabricated in this study using dimple technique based on PMN-PT single crystal and lead-free KNN-KBT-Mn ceramic. The center frequency, bandwidth, and insertion loss of the PMN-PT transducer were 34 MHz, 75%, and 22.9 dB, respectively. For the lead-free probe, the center frequency, bandwidth, and insertion loss were found to be 40 MHz, 72%, and 28.8 dB, respectively. The ultrasonic images of wire phantom and vessels with good resolution were obtained to evaluate the transducer performance. The -6 dB axial and lateral resolutions of the PMN-PT probe were determined to be 58 µm and 131 µm, respectively. For the lead-free probe, the axial and lateral resolutions were found to be 44 µm and 125 µm, respectively. These results suggest that the mechanical dimpling technique has good potential in preparing focused transducers for intravascular ultrasound applications.

Role of chemokines in promoting instability of coronary atherosclerotic plaques and the underlying molecular mechanism.

Our aim was to investigate the role of chemokines in promoting instability of coronary atherosclerotic plaques and the underlying molecular mechanism. Coronary angiography and intravascular ultrasound (IVUS) were performed in 60 stable angina pectoris (SAP) patients and 60 unstable angina pectoris (UAP) patients. The chemotactic activity of monocytes in the 2 groups of patients was examined in Transwell chambers. High-sensitivity C-reactive protein (hs-CRP), monocyte chemoattractant protein-1 (MCP-1), regulated on activation in normal T-cell expressed and secreted (RANTES), and fractalkine in serum were examined with ELISA kits, and expression of MCP-1, RANTES, and fractalkine mRNA was examined with real-time PCR. In the SAP group, 92 plaques were detected with IVUS. In the UAP group, 96 plaques were detected with IVUS. The plaques in the UAP group were mainly lipid 51.04% (49/96) and the plaques in the SAP group were mainly fibrous 52.17% (48/92). Compared with the SAP group, the plaque burden and vascular remodeling index in the UAP group were significantly greater than in the SAP group (P<0.01). Chemotactic activity and the number of mobile monocytes in the UAP group were significantly greater than in the SAP group (P<0.01). Concentrations of hs-CRP, MCP-1, RANTES, and fractalkine in the serum of the UAP group were significantly higher than in the serum of the SAP group (P<0.05 or P<0.01), and expression of MCP-1, RANTES, and fractalkine mRNA was significantly higher than in the SAP group (P<0.05). MCP-1, RANTES, and fractalkine probably promote instability of coronary atherosclerotic plaque.

The inhibitory effect of melatonin on colonic motility disorders induced by water avoidance stress in rats.

OBJECTIVES: Psychological stress is involved in the etiology of functional gastrointestinal disease (FGID). Accumulations of chronic continuous stress associate with the symptoms of the gastrointestinal tract (GIT) including abdominal discomfort, pain, constipation or diarrhea. Melatonin (MT) is a neurohormone which mainly synthesized in the pineal gland and GIT, has been shown to alleviate the stress and regulate the intestinal motility. Although melatonin attenuated abnormal defecation induced by stress, the mechanisms of the effect are not fully elucidated. This study sought to investigate the effect of melatonin (MT) on colonic smooth muscle contractility disorders induced by chronic water avoidance stress (WAS). MATERIALS AND METHODS: 36 adult Wistar rats were divided into three groups [Control+V (vehicle solution), WAS+V, WAS+MT]. The WAS+V and WAS+MT groups were suffered from WAS for one hour daily for 10 days. Melatonin was given 30 min before stress session in the WAS+MT group. Colonic motility was assessed using the numbers of fecal pellet output. The concentrations of melatonin and serotonin (5-HT) were measured through ELISA method. The contractions of isolated colonic strips were assessed through isometric force transducer. RESULTS: The numbers of fecal output was increased in the WAS+V group, and melatonin attenuates the increased fecal pellet output induced by WAS. The concentrations of 5-HT was increased by WAS, and melatonin decreased the augment in the concentration of 5-HT. In the part of contraction recording of colonic smooth muscle, melatonin inhibited the fortified spontaneous contraction induced by WAS, and decreased the amplitude of spontaneous contraction stimulated by Ach and KCl after WAS treatment. CONCLUSIONS: Melatonin could inhibit WAS-induced fecal output pellets by inactivating the 5-HT pathway, may interact with calcium channel and inhibit the influx of calcium.

The AKT1/NF-kappaB/Notch1/PTEN axis has an important role in chemoresistance of gastric cancer cells.

The inherent resistance of tumors to DNA damage often limits the efficacy of chemotherapy. The aim of this work is to explore the potential mechanism for development of chemoresistance in gastric cancer. Our data revealed that AKT1 mRNA and protein expression were induced by doxorubicin (a chemotherapeutic agent); the doxorubicin-induced AKT1 expression and activation increased the binding of NF-kappaB on Notch1 DNA promoter and then promoted the Notch1 transcription and expression; enhanced expression of Notch1 further upregulated PTEN expression through CBF-1 binding to PTEN DNA promoter; and inhibition of AKT1 expression and activity sensitized the gastric cancer cell to doxorubicin treatment in cultured gastric cancer cell lines and xenograft nude mice gastric cancer model. Furthermore, our data demonstrated that both Notch1 and PTEN were absent or minimally expressed in gastric cancer tissue but abundant in paired normal gastric mucosa, and the expression of Notch1 correlated with that of PTEN. Together, these novel results suggested that a novel AKT1/NF-kappaB/Notch1/PTEN axis has an important role in the development of chemoresistance in gastric cancer. Notch1 has an anti-cancer role in gastric cancer.

High frequency PMN-PT single crystal focusing transducer fabricated by a mechanical dimpling technique.

High frequency (∼30MHz and ∼80MHz) focusing ultrasound transducers were fabricated using a PMN-0.28PT single crystal by a mechanical dimpling technique. The dimpled single crystal was used as an active element for the focusing transducer. Compared with a plane transducer, the focusing transducer fabricated with a dimpled active element exhibits much broader bandwidth and higher sensitivity. Besides, a high quality image can be obtained by the 30MHz focusing transducer, in which the -6dB axial and lateral resolution is 27µm and 139µm, respectively. These results prove that the dimpling technique is capable to fabricate the high frequency focusing transducers with excellent performance for imaging applications.

Expression of Vacuolar H+-ATPases and the intracellular pH values in three adenocarcinoma cell lines of digestive system.

Vacuolar H+-ATPases function in bone resorption, pH homeostasis and tumor metastasis, play an important role in regulating the extra- and intracellular pH (pHe and pHi) in various eukaryotic cells. Acidity is one of the main features of the tumors. The Vacuolar H+-ATPases are the primary responsible for the control of tumor microenvironment by proton extrusion to the extracellular medium, which play a crucial role in tumor invasion, metastasis and chemoresistance. Therefore our study aimed to uncover the relationship between Vacuolar H+-ATPases and the pHi value. Three adenocarcinoma cell lines of digestive system including SGC7901, HT29 and PATU8988 were cultured in RPMI-1640 supplemented with 10% fetal bovine serum and antibiotics. BCECF-AM pH-sensitive fluorescent probe was used to measure the pHi value of cells. Western blot and immunofluorescent staining were respectively applied to determine the protein expression and intracellular distribution of Vacuolar H+-ATPases. The pHi value of HT29 was the highest, whereas the pHi value of PATU8988 was the lowest and of SGC7901 was in the midst according to fluorescent intensity of BCECF. Similar results were obtained in the protein expression and the IOD (integral optical density) of Vacuolar H+-ATPases in them. The pHi value indirectly represented by fluorescent intensity of BCECF was positively correlated with protein expression of Vacuolar H+-ATPases in an exponential manner.

Multiple matching scheme for broadband 0.72Pb(Mg(13)Nb(23))O(3)-0.28PbTiO(3) single crystal phased-array transducer.

Lead magnesium niobate-lead titanate single crystal 0.72Pb(Mg(13)Nb(23))O(3)-0.28PbTiO(3) (abbreviated as PMN-PT) was used to fabricate high performance ultrasonic phased-array transducer as it exhibited excellent piezoelectric properties. In this paper, we focus on the design and fabrication of a low-loss and wide-band transducer for medical imaging applications. A KLM model based simulation software PiezoCAD was used for acoustic design of the transducer including the front-face matching and backing. The calculated results show that the -6 dB transducer bandwidth can be improved significantly by using double lambda8 matching layers and hard backing. A 4.0 MHz PMN-PT transducer array (with 16 elements) was fabricated and tested in a pulse-echo arrangement. A -6 dB bandwidth of 110% and two-way insertion loss of -46.5 dB were achieved.

Sodium butyrate induces human colon carcinoma HT-29 cell apoptosis through a mitochondrial pathway.

Some tumours respond favourably to tumour necrosis factor-alpha (TNF-alpha). Despite this preferential sensitivity, resistance to TNF-alpha remains a clinical problem and more interest is now being focused on finding compounds that induce apoptosis through other pathways. Sodium butyrate (NaBt) has anti-tumour effects on colon cancer cells, inhibiting cell growth and promoting differentiation and apoptosis. In this study we investigated whether NaBt induced apoptosis in the human colon cancer cell line HT-29 and examined the intracellular mechanisms involved. Pre-incubation of cells with NaBt significantly increased apoptosis as measured by fluorescence activated cell sorter analysis and mitochondrial membrane potential determination. This effect could be blocked with the caspase inhibitors, z-VAD-fmk (pan-caspase inhibitor), z-DEVD-fmk (caspase-3 inhibitor) and z-LEHD-fmk (caspase-9 inhibitor), but not with z-IETD-fmk (caspase-8 inhibitor). Enhancement of caspase-3 and caspase-9 activities suggests that NaBt induces apoptosis via mitochondrial pathways not involving TNF-alpha.

PMN-PT single crystal thick films on silicon substrate for high-frequency micromachined ultrasonic transducers.

In this work, a novel high-frequency ultrasonic transducer structure is realized by using PMNPT-on-silicon technology and silicon micromachining. To prepare the single crystalline PMNPT-on-silicon wafers, a hybrid processing method involving wafer bonding, mechanical lapping and wet chemical thinning is successfully developed. In the transducer structure, the active element is fixed within the stainless steel needle housing. The measured center frequency and -6 dB bandwidth of the transducer are 35 MHz and 34%, respectively. Owing to the superior electromechanical coupling coefficient (k(t)) and high piezoelectric constant (d(33)) of PMNPT film, the transducer shows a good energy conversion performance with a very low insertion loss down to 8.3 dB at the center frequency.

A safe and efficient strategy for endoscopic resection of large, gastrointestinal lipoma.

BACKGROUND: Gastrointestinal (GI) lipomas are benign, slowly growing, submucosal tumors, which may cause gastrointestinal bleeding, anemia, intussusception, and bowel obstruction. The aim of this study is to explore the safe and effective strategy for endoscopic removal of large GI lipomas. METHODS: During last 10 years, fifteen large and symptomatic GI lipomas were resected under endoscopy in our hospital. In them, two large lipomas with small stalk (< 2 m in diameter) were resected by polypectomy; ten large lipomas with base size greater than 2 cm in diameter were removed using a "subtotal resection." Three other large lipomas with small stalk (< 2 m in diameter) were resected by multistep resection. Endoscopic ultrasonography (EUS) and miniprobe endoscopic ultrasound were performed in six cases from January 2000 to July 2004 to confirm that those lesions were lipomas that were superficial to the muscularis propria. RESULTS: All 15 lesions were successfully removed and were histopathologically confirmed to be lipomas. No severe complications, such as perforation or hemorrhage, developed after endoscopic removal. No recurrence was observed after 1-8 years follow-up endoscopic examination. CONCLUSIONS: Various, large GI lipomas can be removed safely by electrosurgical snare resection under endoscopy following the guidance of the present therapeutic strategy.

Evaluation and analysis of colonoscopy in the diagnosis of 186 cases of ulcerative colitis patients.

The objective of this study was to evaluate the diagnostic value of colonoscopy plus biopsy in patients with ulcerative colitis (UC). Retrospective analysis was performed on clinical data in 186 cases. Erosions, or ulcers, together with mucosal hyperemia and oedema were the most common manifestations of colonoscopy in 87% of patients. In about 56.4% of 186 cases, such manifestations occurred in the rectum and the sigmoid colon. Nearly 65.6% of the patients had a chronic intermittent clinical course. One case developed colon cancer, and another case had toxic megacolon; each case represents 0.05% of the total 186 patients. Therefore, prevalence of both malignancy and complication is low. Colonoscopy plus biopsy is considered to be the major means of the diagnosis of UC, demonstrating its value in differential diagnosis.

Differential diagnosis between Crohn's disease and intestinal tuberculosis in China.

To evaluate the values of clinical findings in differential diagnosis between Crohn's disease (CD) and intestinal tuberculosis (ITb), so that better diagnosis strategies could be found, we analysed the records of 30 patients with ITb and 30 patients with CD retrospectively. We reviewed the cardinal symptomatic and physical, radiological, colonoscopic, pathological findings in the patients. Some cardinal symptomatic and physical, radiographic and colonscopic features of CD and ITb were positive correlation. Its Pearson correlation coefficients were 0.976, 0.953 and 0.961, respectively (p = 0.000, 0.003 and 0.000). Some histological features of CD and ITb had no correlation. Its Pearson correlation coefficient was 0.140 (p = 0.765). It is difficult to differentiate CD from ITb in clinical practice. The differential diagnosis depends largely upon colonoscopy and histopathology.

Clinical investigation on coexisting of duodenal ulcer and gastric cancer in China.

The aim of this study was to investigate the prevalence of coexistent duodenal ulcer and gastric cancer in China, then to explore the features of clinical manifestations, endoscopy, pathology and possible pathogenesis. A retrospective analysis has been made on medical records in Remin Hospital, Wuhan University, Hubei Province, China from January 1991 to December 2002. 37 cases of coexistent duodenal ulcer and gastric cancer were found. 24.3% (9/37) had previous history of duodenal ulcer. 81.0% (30/37) of them lack alarm symptoms or signs and 87.1% (27/31) had alleviation in abdominal pain by acid inhibitor. Duodenal ulcer was single in all cases with seven in A1 stage, three in A2 stage, one in H1 stage, one in H2 stage, seven in S1 stage and 18 in S2 stage. 89.2% (33/37) of concurrent gastric cancer were in the corpus and antrum, with 78.1% (29/37) of them belonging to Bormann type II and 87.1% (27/37) being moderately differentiated adenocarcinoma. 83.7% of patients (31/37) had positive rapid urease test. The coexisting gastric cancer in patients with duodenal ulcer is infrequent but not rare. Gastroscopy screening and routine follow-up are necessary for patients with duodenal ulcer. Helicobacter pylori may be important pathogen for it. Helicobacter pylori eradication is recommended in patients with duodenal ulcer to reduce the risk of contaminant gastric cancer.