SYNTHESIS AND CHARACTERIZATION OF POLYSIALIC ACID/CARBOXYMETHYL CHITOSAN HYDROGEL WITH POTENTIAL FOR DRUG DELIVERY

A novel hydrogel was prepared from polysialic acid (PSA) and carboxymethyl chitosan (CMCS) using glutaraldehyde as the cross-linking agent. The resulting PSA-CMCS hydrogel exhibited pH sensitivity, in which the swelling ratio under acidic conditions was higher than those under neutral or alkaline conditions. The swelling ratio of PSA-CMCS hydrogel at equilibrium depended on the medium pH, the cross-linking agent concentration, and the ratio of PSA to CMCS (w/w). Bovine serum albumin (BSA) and 5-fluorouracil (5-FU) were used as model drugs to prepare hydrogel delivery systems. The loading efficiencies of the hydrogel for BSA and 5-FU were 26.25 and 36.74%, respectively. Release behaviors of BSA and 5-FU were influenced by the pH. MTT assays confirmed that PSA-CMCS hydrogel has no cytotoxicity toward the NIH-3T3 cell line; in fact, the 100% aqueous extract of the PSA-CMCS hydrogel enhanced cell growth. These results suggest that PSA-CMCS hydrogel may be a promising pH-sensitive delivery system, especially for hydrophobic chemicals.

Prevalence and risk factors for clinically significant upper gastrointestinal bleeding in patients with severe acute pancreatitis

OBJECTIVE

To investigate the prevalence and risk factors of upper gastrointestinal bleeding (UGIB) in patients with severe acute pancreatitis (SAP).

METHODS

Altogether 101 patients were admitted to the Department of Gastroenterology, Changhai Hospital, Second Medical Military Hospital from July 2006 to June 2010 due to SAP. Their prevalence and risk factors of UGIB were retrospectively analyzed.

RESULTS

In total, 18 (17.8%) patients developed UGIB and 13 received endoscopic examination, which yielded six cases of acute gastric mucosal lesions (AGML), five of peptic ulcers (PU) and two of pancreatic necrotic tissue invading the duodenal bulb and presenting as multilesion, honeycomb-like ulcer. The mortality rate of UGIB patients was much higher than that of non-UGIB patients (44.4% vs 10.8%, P = 0.0021). Univariate analysis revealed that the risk factors for UGIB included the Acute Physiology and Chronic Health Evaluation II (APACHE II) score, computed tomography severity index (CTSI), Ranson score, arterial blood pH and PaO2 , serum blood urea nitrogen and creatinine concentrations, platelet count, shock, sepsis and organ failure, mechanical ventilation, heparinized continuous renal replacement therapy and total parenteral nutrition. Multivariate logistic regression revealed that APACHE II score and CTSI were significant risk factors while PaO2 was the protective factor for UGIB in SAP.

CONCLUSIONS

UGIB is a common complication with poor prognosis due mainly to PU and AGML. Patients having SAP with high APACHE II scores and CTSI or low PaO2 should be considered to be at high risk for UGIB.

An increase of curdlan productivity by integration of carbon/nitrogen sources control and sequencing dual fed-batch fermentors operation

Curdlan is produced by Agrobacterium sp. ATCC 31749 under nitrogen-limited conditions not associated with cell growth. A novel curdlan production process was developed based on the different nutrient requirements for microbial cell growth and its efficiency was increased by integrating carbon/nitrogen sources control and sequencing dual fed-batch fermentors operation. By feeding ammonium solution to supply abundant nitrogen source and controlling pH in Fermentor I, cell growth was accelerated. High cell density of 29 g/L was attained. The culture broth in Fermentor I was then inoculated into sequencing Fermentor II which alleviated the high requirement for dissolved oxygen and accumulation of inhibitory metabolic by-products during curdlan production. Fermentor I promoted cell growth. Curdlan production started instantaneously in Fermentor II. By feeding nutrient solution with high carbon/nitrogen ratio and NaOH solution for pH adjustment, a feasible and optimal curdlan production process was formulated. The productivity, conversion efficiency and curdlan yield were achieved of 0.98 g/(L h), 57% (w) and 67 g/L, respectively. Such novel process can be scaled up for significant cost reduction at the industrial level.

Risk factors for pancreatic infection in patients with severe acute pancreatitis: an analysis of 163 cases

OBJECTIVE

We aimed to identify the risk factors for predicting pancreatic infection in patients with severe acute pancreatitis (SAP).

METHODS

In all, 163 patients with SAP were included and divided into two groups based on the presence or absence of pancreatic infection. Their demographic and clinical characteristics, laboratory examination results, complications and treatment modalities were collected from their medical records. Variables were initially screened by univariate analysis and those with statistical significance were then filtered by multivariate analysis to determine the independent risk factors for pancreatic infection in SAP.

RESULTS

Patients having SAP with pancreatic infection had a lower partial pressure of arterial carbon dioxide (PaCO2 ), peripheral white blood cell count and alkaline phosphatase levels, together with a higher computed tomography severity index (CTSI) than those without pancreatic infection, while their lactate dehydrogenase (LDH) levels and blood urea nitrogen were much higher. Pancreatic infection was also more common in patients receiving late fluid resuscitation than in those receiving early fluid resuscitation. Multivariate analyses revealed that increased LDH level, high CTSI, delayed fluid resuscitation and hypoxemia were independent risk factors for pancreatic infection in SAP. The sensitivity, specificity, positive and negative predictive values for a model combining the parameters in predicting pancreatic infection were 84%, 97%, 88% and 96%, respectively, with a cut-off value of 0.393, and the area under the receiver operating characteristic curve was 0.923.

CONCLUSION

Increased LDH, high CTSI, delayed fluid resuscitation and hypoxemia are independent risk factors for predicting pancreatic infection in patients with SAP.

Peptic ulcer bleeding in China: a multicenter endoscopic survey of 1006 patients

OBJECTIVE

We aimed to describe the clinical picture, management and outcomes of Chinese patients with peptic ulcer bleeding (PUB), especially in those with high risks.

METHODS

A multicenter endoscopic survey was conducted. All consecutive patients with endoscopy confirmed PUB from October 2010 to June 2011 were enrolled. Data including patients' gender, age, symptoms and endoscopic findings, Forrest classification, and endoscopic and medical treatment were documented. High-risk ulcer was defined as Forrest grades Ia to IIb upon endoscopy. Rates of rebleeding, surgery and mortality were recorded.

RESULTS

In all, 1006 patients were included. Of these 437 (43.4%) were categorized with high-risk PUB, among whom 110 (25.2%) received endoscopic treatment, and the success rate was 99.1%. Rebleeding rates 1-3 days, 4-5 days and 6-30 days after treatment in high-risk patients who did and did not receive endoscopic treatment were 10.9% versus 10.4%, 3.6% versus 3.7% and 0.9% versus 1.5%, respectively. The surgery rates of high-risk patients with or without endoscopic treatment were 1.8% (2/110) versus 1.8% (6/327). During the 9-month study period, two patients with high-risk PUB died, therefore, the overall mortality rate of high-risk PUB was 0.5% (2/437).

CONCLUSION

The study suggests that the proportions of high-risk PUB in China is 43.4%, while rebleeding and surgery rate after endoscopic treatment as well as the mortality rate of high-risk PUB in China are 15.6%, 1.8% and 0.5%, respectively.

Cyst fluid carcinoembryonic antigen concentration and cytology by endosonography-guided fine needle aspiration in predicting malignant pancreatic mucinous cystic neoplasms

OBJECTIVE

To assess the value of carcinoembryonic antigen (CEA) level and cytology examination obtained by endosonography-guided fine needle aspiration (EUS-FNA) in predicting the malignancy of pancreatic mucinous cystic neoplasm (MCN).

METHODS

The data of patients with pancreatic MCN who underwent EUS-FNA in Changhai Hospital, Second Military Medical University (Shanghai, China) from November 2005 to April 2010 were collected and analyzed. The area under receiver operating characteristic (ROC) curve of cyst fluid CEA, sensitivity, specificity, positive (PPV) and negative predictive value (NPV) of the cytology as well as cyst fluid CEA were determined.

RESULTS

Of the 20 MCNs confirmed by surgical pathology, 10 were malignant and the remainder were premalignant. Cytology had some value in differentiating malignant from premalignant MCN with a sensitivity of 60.0%, specificity of 100.0%, PPV of 100.0% and NPV of 71.4%. CEA of > 692.8 ng/mL was able to predict malignancy (P = 0.007) with sensitivity of 80.0%, specificity of 90.0%, PPV of 88.9% and NPV of 81.8%, and its area under ROC curve was 0.855.

CONCLUSION

Cyst fluid CEA level and cytology obtained by EUS-FNA are useful for predicting the malignancy of pancreatic MCN.

Acid inhibition effect of ilaprazole on Helicobacter pylori-negative healthy volunteers: an open randomized cross-over study

OBJECTIVE

The aim of this study was to evaluate the effects and safety of different doses of ilaprazole on healthy volunteers without a Helicobacter pylori infection.

METHODS

A total of 12 healthy Chinese volunteers were enrolled and divided into four groups randomly, with a 5-day treatment of oral ilaprazole 5mg, 10mg and 20mg or omeprazole 20mg, respectively. After an interval of a 14-day washout phase, each was switched to another dose group and eventually completed all four regimens. The percentage time of intragastric pH>4 was the major index. The polymorphisms of the metabolic enzyme CYP2C19 in these volunteers were also detected.

RESULTS

The percentage time of intragastric pH>4 in the ilaprazole 5, 10 and 20mg groups were 80.4%, 88.1% and 91.0%, respectively, during the first 24h, compared to that of the 20mg omeprazole group (76.6%, P>0.05). Ilaprazole 20mg provided a significant higher mean 24-h pH than that of the same dose of omeprazole both on Day 1 (7.78 vs 6.67, P<0.01) and Day 5 (7.95 vs 7.44, P<0.05). No CYP2C19-dependent difference or obvious adverse effect were found in any ilaprazole groups.

CONCLUSION

Low dose ilaprazole offers a gastric acid inhibition comparable to a routine dose of omeprazole, and further investigations in patients with acid-associated diseases are needed.

Changes in gene transcription and protein expression involved in the response of Agrobacterium sp. ATCC 31749 to nitrogen availability during curdlan production

The changes in transcription of genes involved in nitrogen metabolism and curdlan biosynthesis, and total protein expression were firstly analyzed to define the responses of Agrobacterium sp. ATCC 31749 to nitrogen source availability during curdlan fermentation. The transcription of all nitrogen metabolism and regulation genes increased significantly under nitrogen limitation. The genes of carbon (exoC) and nitrogen (ntrB, ntrC, and nifR) metabolism showed distinctive transcriptional responses to nitrogen limitation. Their relative expression level was increased by 14, 9, 7 and 7-fold, respectively. Two-dimentional electrophoresis (2-DE) revealed that the expression of 14 proteins were elevated and 6 proteins were down-regulated significantly under nitrogen starvation. Furthermore, 4 proteins (GroEL, ABC transporter, Atu1730 and enoyl-acyl carrier protein reductase) in which the expression level changed significantly were identified. The results showed that Agrobacterium sp. regulates its carbon flux and nitrogen assimilation effectively for better survival.

The efficacy of Combizym in the treatment of Chinese patients with dyspepsia: a multicenter, randomized, placebo-controlled and cross-over study: Shanghai Combizym Clinical Cooperative Group

OBJECTIVE

To evaluate the efficacy and safety of Combizym treatment in Chinese patients with dyspepsia.

METHODS

In this multicenter, randomized, placebo-controlled cross-over study, a total of 151 patients (76 men and 75 women, mean age: 44.67 +/- 6.46 years, range: 22-67 years) with dyspepsia whose symptoms were not relieved by placebos were recruited. They were randomly divided into group A (79 patients, 2 weeks of Combizym treatment, two tablets post-meal, t.i.d.; then 1 week of wash-out, followed by 2 weeks of placebo treatment, two tablets post-meal, t.i.d.) or group B (72 patients, 2 weeks of placebo treatment, two tablets post-meal, t.i.d. then one week of wash-out, followed by 2 weeks of Combizym treatment, 2 tablets post-meal, t.i.d.). The index of severity of the dyspepsia symptoms was evaluated before and after each treatment phase with Combizym or the placebo.

RESULTS

Compared with the placebo, 2 weeks of Combizym treatment decreased the severity index of dyspepsia symptoms significantly (27.64 +/- 1.77 to 9.72 +/- 1.33 vs 23.99 +/- 1.28 to 22.03 +/- 1.40, P < 0.01). The efficacy rates of Combizym and the placebo on dyspepsia were 89.63% and 21.68%, respectively (P < 0.01). According to the improvement of symptoms index, individual dyspepsia symptoms that could be attenuated by Combizym therapy were anepithymia, abdominal distension, belching, diarrhea, abdominal pain, epigastric burning. None of patients reported adverse events during the study.

CONCLUSION

Combizym treatment effectively ameliorates dyspepsia symptoms in Chinese patients, with satisfactory safety and compliance.

Changes in endothelin-1 gene expression in the gastric mucosa of rats under cold-restraint-stress

OBJECTIVE

To investigate in rats the role of endothelin (ET)-1 gene expression in the development and progression of acute gastric mucosal lesions (AGML) induced by stress, and the effect of BQ-123 (a special ETA receptor antagonist) on the AGML.

METHODS

A rat model of gastric ulcer induced by cold-restraint-stress (CRS) was used. ET-1 concentrations in the plasma and gastric mucosa were determined by radioimmunoassay (RIA), gastric mucosa blood flow (GMBF) was measured with a laser Doppler flow meter, the ulcer index (UI) was used to estimate the degree of gastric mucosa damage and the expression levels of ET-1 mRNA in the gastric mucosa were measured using dot blot and reverse transcription polymerase chain reaction (RT-PCR). Different doses of BQ-123 were administered via the left femoral vein prior to the stress in order to observe the effects of BQ-123 on the ET-1 concentrations in the plasma and gastric mucosa, the GMBF and the UI.

RESULTS

Compared with the normal controls, the ET-1 concentrations in the plasma and gastric mucosa of the stressed rats were increased significantly (P < 0.05), the GMBF was decreased markedly (P < 0.01), and the UI increased dramatically (P < 0.01). There was a significant positive correlation between the gastric mucosal EF-1 concentration and the UI (r = 0.98, P < 0.01), and a significant negative correlation between the gastric mucosal ET-1 concentration and GMBF (r = -0.89, P < 0.01) and also between the UI and GMBF (r = -0.98, P < 0.01). The expression level of ET-1 mRNA in the gastric mucosa of the stressed rats increased significantly compared with that of the normal controls (P < 0.01), and there was a positive correlation between the expression of ET-1 mRNA and the ET-1 concentration in the gastric mucosa (r = 0.93, P < 0.01). Compared with the untreated animals, the GMBF was increased (P < 0.01) and the UI decreased significantly (P < 0.01) in the BQ-123-treated rats, and the dose of BQ-123 correlated with the degree of change in the GMBF and UI; however, the ET-1 concentrations of either the plasma or the gastric mucosa did not change markedly in the BQ-123-treated animals (P > 0.05).

CONCLUSION

The present study showed that the level of expression of ET-1 mRNA and the synthesis of ET-1 in the gastric mucosa both increased significantly, which suggests that the increased concentration of endogenous ET-1 may be involved in the development and progression of stress ulcer (acute gastric mucosa lesion). The mechanism of action may be associated with a reduction of GMBF induced by ETAR-mediated vasoconstriction. BQ-123 can dose-dependently attenuate significantly the degree of damage to the gastric mucosa induced by stress, and may have therapeutic benefits for stress ulcer.