Highly porous nitrocellulose membranes were prepared by a solvent casting technique for the first time to immobilize α-amylase. An affinity dye, namely Cibacron Blue F3GA (CB), was incorporated covalently within the structure. The nitrocellulose–CB derivatized membranes were used for the immobilization of a starch degrading enzyme, α-amylase. Optimum conditions of immobilization for highest apparent activity were determined as pH 6.0, temperature 50°C and initial enzyme concentration 0.317 KNU/l. Under these optimum conditions, maximum enzyme immobilization yield was around 21% of the initial amount of the enzyme in the solution. Performance of free and immobilized enzymes at the same amount was compared for repeated runs. Up to the third use, immobilized enzyme showed higher activity than that of free enzyme mainly due to higher enzyme concentration in the membrane structure, then the apparent activity decreased gradually. However, when regenerated by switching pH to cause contraction/expansion of the structure, the membrane showed the highest activity, almost 2.5 times than that of the free enzyme. This unusual feature along with inexpensive cost may well make the nitrocellulose membrane an economical material for industrial application in glucose syrup production. 相似文献
Aim The effect of 8 weeks′ streptozotocin (STZ)-
induced diabetes and aminoguanidine (AMNG), the
inhibitor of advanced glycosylation reaction, treatment
on arteriolar reactivity to vasoactive substances
was investigated in vitro.
Materials and Methods Studies were performed in
untreated control rats (n = 10), STZ-induced (60 mg/kg
i.v.) diabetic rats (n = 10), AMNG-treated (600 mg/l
given in drinking water throughout 8 weeks) control
rats (n = 10) and AMNG-treated (600 mg/l given in
drinking water, beginning at 72h after STZ and
throughout 8 weeks of diabetes) diabetic rats (n = 10).
Results are expressed as the mean ±s.e. Relaxant
responses are expressed as a percentage (%) relaxation
of noradrenaline-induced tone. Statistical comparisons
were made by one-way analysis of variance
(ANOVA) followed by Tukey–Kramer multiple
comparisons test.
Results 1. The decreased body weights (205 ± 6 g)
and increased blood glucose levels (583 ± 8 mg/dl) of
diabetic rats were partially restored by treatment of
aminoguanidine (253 ± 6 g, p < 0.05 and 480 ± 14 mg/dl, p < 0.001, respectively). 2. Diabetes caused a 71%
deficit in maximal endothelium-dependent relaxation
to acetylcholine for noradrenaline precontracted
aortas (p < 0.001). AMNG treatment prevented the
diabetes-induced impairment in endothelium dependent
relaxation (58 ± 8%) to acetylcholine, maximum
relaxation remaining in the non-diabetic range
(78 ± 4%). 3. Neither diabetes nor treatment affected endothelium-independent relaxation (pD2 and max.
Relax.) to sodium nitroprusside. 4. Vasoconstrictor
responses (pD2 and Max. Contraction) to noradrenaline
and KCl were not influenced by the diabetic
state and treatment.
Conclusion Our data suggest that 8 weeks of
experimental diabetes is associated with a decreased
endothelium-dependent vasodilatation. AMNG
treatment may prevent diabetes-induced endothelial
dysfunction. This may be mediated via the prevention
of advanced glycosylation end product formation,
the enhanced release of vasodilator substances
such as prostacyclin, the increased elasticity of blood
vessels, the antioxidant activity and inhibitor activity
of enzyme aldose-reductase by AMNG. 相似文献
Although the availability of thyroid cyst fluid is easy by fineneedle aspiration, less is known about the biochemical composition
of thyroid cyst fluid. The authors have, therefore, determined the biochemical composition of 18 benign thyroid cyst fluid
specimens. They found that the activities of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and the concentrations
of total protein, total bilirubin, and uric acid were highly increased in thyroid cyst fluid specimens when compared with
normal human serum specimens. The concentrations of glucose, cholesterol, and triglycerides in cyst fluid were within normal
serum limits. Selenium (Se) concentrations in most cyst fluids were low. Moreover, there was no correlation between Se and
other biochemical parameters. Protein electrophoresis of cyst fluid specimens yielded high concentrations of α1 and especially α2 globulin fractions indicating an inflammation. The concentrations or activities of biochemical analytes were not significantly
different in pure and mixed cysts. Those parameters were also not significantly different between cyst fluids of different
colors. The gross appearance of the fluid and the presence of certain biochemical analytes were consistent with a hemorrhagic
origin of most of the cyst fluid specimens. However, some biochemical markers indicate that autolysis or necrosis of thyroid
tissue may also contribute the composition of thyroid cyst fluid. The reason for lower Se concentration in the thyroid cyst
fluid may be the lower Se concentration in the Turkish population. These results also suggest that the fluid color or nature
of cyst, e.g., pure or mixed cyst, is not a main determinant of biochemical composition of benign thyroid cyst fluid. 相似文献
Prion infections cause neurodegeneration, which often goes along with oxidative stress. However, the cellular source of reactive oxygen species (ROS) and their pathogenetic significance are unclear. Here we analyzed the contribution of NOX2, a prominent NADPH oxidase, to prion diseases. We found that NOX2 is markedly upregulated in microglia within affected brain regions of patients with Creutzfeldt-Jakob disease (CJD). Similarly, NOX2 expression was upregulated in prion-inoculated mouse brains and in murine cerebellar organotypic cultured slices (COCS). We then removed microglia from COCS using a ganciclovir-dependent lineage ablation strategy. NOX2 became undetectable in ganciclovir-treated COCS, confirming its microglial origin. Upon challenge with prions, NOX2-deficient mice showed delayed onset of motor deficits and a modest, but significant prolongation of survival. Dihydroethidium assays demonstrated a conspicuous ROS burst at the terminal stage of disease in wild-type mice, but not in NOX2-ablated mice. Interestingly, the improved motor performance in NOX2 deficient mice was already measurable at earlier stages of the disease, between 13 and 16 weeks post-inoculation. We conclude that NOX2 is a major source of ROS in prion diseases and can affect prion pathogenesis. 相似文献
Dysfunction of the gastrointestinal tract (GIT) is one of the most common non-motor symptom of Parkinson’s Disease (PD). Pathological processes causing PD were suggested to initiate in the enteric nervous system (ENS) and proceed to the central nervous system (CNS). There are studies showing that low-carbohydrate ketogenic diets can improve motor symptoms of PD. Caprylic acid (C8) is the principal fatty acid component of the medium-chain triglycerides in the ketogenic diets. In this study, we aimed to evaluate the effects of caprylic acid, in neurotoxin exposed zebrafish focusing on the relationship between intestinal and brain oxidative stress and inflammation.
Methods
Adult zebrafish were exposed to rotenone (5 μg/L) (R group) and caprylic acid (20 and 60 mg/mL) (L?+?HDCA and R?+?HDCA groups) for 30 days. At the end of 30 days locomotor activities were determined. Levels of lipid peroxidation (LPO), nitric oxide, glutathione and superoxide dismutase and glutathione S-transferase activities were determined by spectrophotometric methods and gene expressions of tnf?, il1, il6, il21, ifn? and bdnf were evaluated by RT-PCR in the brain and intestinal tissues of zebrafish.
Results
Caprylic acid ameliorated LPO, NO, SOD and the expressions of tnf?, il1, il6, il21, ifn? and bdnf in brain and intestines. Locomotor activities were only ameliorated in high dose R?+?HDCA group.
Conclusions
Caprylic acid ameliorated the neurotoxin-induced oxidative stress and inflammation both in the brain and intestines and enhanced locomotor activity in zebrafish.