Diagnosis and treatment of post-cholecystectomy diarrhoea.

The incidence of cholecystitis is relatively high in developed countries and may usually be attributed to gallstones, the treatment for which involves complete surgical removal of the gallbladder (cholecystectomy). Bile acids produced following cholecystectomy continue to flow into the duodenum but are poorly absorbed by the colon. Excessive bile acids in the colon stimulate mucosal secretion of water and electrolytes leading, in severe cases, to diarrhoea. Bile acid diarrhoea (BAD) is difficult to diagnose, requiring a comprehensive medical history and physical examination in combination with laboratory evaluation. The current work reviews the diagnosis and treatment of BAD following cholecystectomy.

CONDITIONAL PRODUCTION OF A FUNCTIONAL FISH GROWTH HORMONE IN THE TRANSGENIC LINE OF NANNOCHLOROPSIS OCULATA (EUSTIGMATOPHYCEAE)(1).

Plasmid phr-YPGHc, containing the fish growth hormone (GH) cDNA driven by a heat shock protein 70A promoter and a RUBISCO SSU 2 promoter, was transferred into the protoplast of marine microalga Nannochloropsis oculata (Droop) D. J. Hibberd by electroporation. Four transgenic clones were obtained in which the transferred phr-YPGHc was integrated into the genome and existed stably at least until the 50th generation. When we treated these transgenic microalgae by heat shock, the heterologous fish GH was produced in the amount of 0.42 to 0.27 µg · mL(-1) from the 50 mL of medium. We incubated artemia with the wildtype and transgenic N. oculata for 6 h and then fed these microalgae-treated artemia to red-tilapia larvae. After feeding, the growth of larvae that were fed artemia incubated with transgenic microalgae was greater (i.e., statistically significant: P < 0.05) than that of larvae that were fed artemia incubated with nontransgenic microalgae: 316% versus 104% in weight gain, and 217% versus 146% in body length increase, respectively. Therefore, the N. oculata enables production of functional GH, and we propose that it might be an excellent bioreactor material.

Potential of a simple solid-phase extraction method coupled to analytical and bioanalytical methods for an improved determination of microcystins in algal samples.

Artemia assays and protein phosphatase assays are commonly used for the screening of microcystins (MCs) in algal samples instead of the standard mouse toxicity assay. However, it has been shown that their results are often biased because of the matrix effects. To eliminate the possible interferences in the algal matrices, a new solid-phase extraction (SPE) method using silica gel as a sorbent was developed and evaluated. Results show that this SPE method could not only reduce the toxicity of the Microcystis samples towards brine shrimp by 50-80% but also eliminate 90-100% of the endogenous phosphatase activity from Spirulina and Chlorella samples, thus improving the determination of microcystins in algal samples using either of the two bioanalytical methods. The application of this SPE method as an off-line cleanup for high-performance liquid chromatography (HPLC) with UV detection is also described in this study. After SPE, the HPLC chromatograms of Microcystis samples have clear baselines that have no interferences with the analyte peaks.

Purification and characterization of a novel haemagglutinin from Chlorella pyrenoidosa.

We previously identified a strong haemagglutination activity in the freshwater unicellular green alga, Chlorella pyrenoidosa. Here, we sought to purify and characterize the haemagglutinin associated with this activity. Ammonium sulfate precipitation, gel filtration on sephacryl S-200 and DEAE-Sepharose ion-exchange chromatography were used to purify the haemagglutinin, which was designated CPH (Chlorella pyrenoidosa haemagglutinin). The molecular weight of CPH was estimated as 58 kDa by SDS-PAGE and 60 kDa by gel filtration of the native protein, indicating that this haemagglutinin exists as a monomer. The haemagglutinin activity of CPH was inhibited by glycoproteins, especially yeast mannan, but not by monosaccharides or disaccharides, indicating that CPH is carbohydrate-specific. In addition to the composition of CPH shown to be rich in glycine and acidic amino acids, heamagglutinating activity of CPH was insensitive to variations in pH or the presence of divalent cations, and atomic force microscopy revealed that the protein is rod-shaped. These results indicate that the characteristics of CPH are consistent with its identification as a haemagglutinin, and suggest that CPH may be a viable candidate for applications in a variety of biomedical fields.

Comparison of protein phosphatase inhibition activities and mouse toxicities of microcystins.

Eight naturally purified microcystins (MCs), including MC-LR, -FR, -WR, -RR, [d-Asp(3)]MC-FR, -WR, -RR, and [Dha(7)]MC-RR were utilized to determine the effects of amino acid substitutions and modifications on MC-induced protein phosphatase inhibition activity and mouse toxicity. Catalytic subunits of protein phosphatase 1 (PP-1) and 2A (PP-2A) were purified and subjected to the inhibition assays, and intraperitoneal injection was used to administer MCs into mice for the toxicity assay. It is found that the replacement of the non-polar amino acid l-leucine at the second position of these heptacyclic peptide toxins by a polar l-arginine reduces their mouse toxicities and inhibitory activities against PP-1 and PP-2A to different extends. Demethylation of methyldehydroalanine (Mdha) at the seventh amino acid of MC-RR exhibits the least mouse toxicity and phosphatase inhibition. The loss of a methyl group on the common methylaspartic acid (MeAsp) at the third position of MC-FR, -WR, and -RR does not alter their toxicity levels, but dominantly reduces their activities in PP-1 inhibition compared to other substitutions or modifications. This suggests that the methyl group on MeAsp is also important for MCs inhibition. However, such a tendency is not observed for PP-2A. By comparing the LD(50) values of the mouse toxicity assay and IC(50) values of the PP-1 and PP-2A inhibition assay of eight MCs using linear regression, it is evident that the MC-induced toxicity is much more related to the inhibition of PP-2A than PP-1, which suggests that PP-2A inhibition may play a major role in the MC-induced mouse toxicity.

Expression of TNF-alpha and VEGF in the esophagus of portal hypertensive rats.

AIM: To investigate the expression of tumor necrosis factor-alpha (TNF-alpha) and vascular endothelial growth factor (VEGF) in the development of esophageal varices in portal hypertensive rats. METHODS: Thirty male Sprague-Dawley (SD) rats in the model group in which a two-stage ligation of portal vein plus ligation of the left adrenal vein was performed, were divided into three subgroups (M(7), M(14), and M(21)) in which the rats were kiued on the seventh day, the 14(th) d and the 21 d after the complete portal ligation. Thirty male SD rats, which underwent the sham operation in the control group, were also separated into three subgroups (C(7), C(14) and C(21)) corresponding to the models. The expression of TNF-alpha and VEGF in the esophagus of all the six subgroups of rats were measured with immunohistochemical SP technique. RESULTS: The portal pressure in the three model subgroups was significantly higher than that in the corresponding control subgroups (23.82+/-1.83 vs 11.61+/-0.86 cmH(2)O, 20.90+/-3.27 vs 11.43+/-1.55 cmH(2)O and 20.68+/-2.27 vs 11.87+/-0.79 cmH(2)O respectively, P<0.01), as well as the number (9.3+/-1.6 vs 5.1+/-0.8, 11.1+/-0.8 vs 5.4+/-1.3 and 11.7+/-1.5 vs 5.2+/-1.1 respectively, P<0.01) and the total vascular area (78 972.6+/-3 527.8 vs 12 993.5+/-4 994.8 mum(2), 107 207.5+/-4 6461.4 vs 11 862.6+/-5 423.2 mum(2) and 110 241.4+/-49 262.2 vs 11 973.7+/-3 968.5 mum(2) respectively, P<0.01) of submucosal veins in esophagus. Compared to the corresponding controls, the expression of TNF-alpha and VEGF in M(21) was significantly higher (2.23+/-0.30 vs 1.13+/-0.28 and 1.65+/-0.38 vs 0.56+/-0.30 for TNF-alpha and VEGF respectively, P<0.01), whereas there was no difference in M(7) (1.14+/-0.38 vs 1.06+/-0.27 and 0.67+/-0.35 vs 0.50+/-0.24 for TNF-alpha and VEGF respectively, P>0.05) and M(14) (1.20+/-0.25 vs 1.04+/-0.26 and 0.65+/-0.18 vs 0.53+/-0.25 for TNF-alpha and VEGF respectively, P>0.05). And the expression of TNF-alpha and VEGF in M(21) was significantly higher than that in M(7) (2.23+/-0.30 vs 1.14+/-0.38 and 1.65+/-0.38 vs 0.67+/-0.35 for TNF-alpha and VEGF respectively, P<0.01) and M(14) (2.23+/-0.30 vs 1.20+/-0.25 and 1.65+/-0.38 vs 0.65+/-0.18 for TNF-alpha and VEGF respectively, P<0.01), but there was no difference between M(7) and M(14) (1.14+/-0.38 vs 1.20+/-0.25 and 0.67+/-0.35 vs 0.65+/-0.18 for TNF-alpha and VEGF respectively, P>0.05). CONCLUSION: In the development of esophageal varices in portal hypertensive rats, increased TNF-alpha and VEGF may be not an early event, and probably play a role in weakening the esophageal wall and the rupture of esophageal varices.

[Laser inducing mucosal fibrosis for preventing recurrence of esophageal varices].

OBJECTIVE: To investigate the prevention of esophageal varices recurrence by laser inducing esophageal mucosal fibrosis. METHODS: Our study included 42 patients after esophageal varices eradicated by endoscopic varices ligation, and they were divided into 2 groups randomly, each group included 21 patients. One group was assigned to received laser treatment, and indocyanine green solution (1 mg/ml) was injected submucosally, a diode laser (power 10 watts) was applied to the surface from the esophagogastric junction to 5 cm above it. Another group was controlling without any treatments. All patient were followed up by endoscopy every 3 months until 12 months. RESULTS: Laser irradiation was performed safely without any major complications. And lower esophageal mucosa produced fibrosis widely after laser irradiated 1 month. After 12 months follow up, the cumulative recurrence rate was significantly lower than the control group, 14% (3/21) vs 43% (9/21) (chi(2) = 4.20, P < 0.05). CONCLUSIONS: Our study indicates that laser inducing mucous fibrosis is safely and can prevent recurrence of esophageal varices.