Mucosal layers and related nerve fibres in non-chagasic and chagasic human colon—a quantitative immunohistochemical study

Chagasic megacolon is accompanied by extensive myenteric and, simultaneously, moderate submucosal neuron loss. Here, we examined changes of the innervation pattern of the lamina propria (LP) and muscularis mucosae (MM). Two alternating sets of cryosections were taken from seven non-chagasic colonic and seven chagasic megacolonic specimens (the latter included both the dilated megacolonic and the non-dilated transitional oral and anal zones) and were immunohistochemically triple-stained for smooth-muscle actin (SMA), synaptophysin (SYN) and glial acid protein S100 and, alternatively, for SMA, vasoactive intestinal peptide (VIP) and somatostatin (SOM). Subsequent image analysis and statistical evaluation of nervous tissue profile areas revealed that, in LP, the most extreme differences (i.e. increase in thickness or decrease in nerve, glia and muscle tissue profile area, respectively) compared with control values occurred in the dilated megacolonic zone itself. In contrast, the most extreme differences in the MM were in the anal-to-megacolonic zone (except the profile area of muscle tissue, which was lowest in the megacolonic zone). This parallels our previous results in the external muscle coat. A partial and selective survival of VIP-immunoreactive in contrast to SOM-immunoreactive nerve fibres was observed in both mucosal layers investigated. Thus, VIPergic nerve elements might be crucial for the maintenance of the mucosal barrier. The differential changes of neural tissue parameters in LP and MM might reflect a multifactorial rather than a pure neurogenic development of megacolon in chronic Chagas’ disease.     

Efficacy of different types of aerobic exercise in fibromyalgia syndrome: a systematic review and meta-analysis of randomised controlled trials

Introduction  

The efficacy and the optimal type and volume of aerobic exercise (AE) in fibromyalgia syndrome (FMS) are not established. We therefore assessed the efficacy of different types and volumes of AE in FMS.     

The buffering capacity of the internal phase of thylakoids and the magnitude of the pH changes inside under flashing light

The buffering capacity inside thylakoids is determined and the magnitude of flash-induced pH changes inside is calibrated in the pH range from 6.4 to 8.1. The work is based on flash-induced absorption changes of neutral red in a chloroplast suspension in which the outer phase is strongly buffered by bovine serum albumin. It is shown that neutral red is bound inside thylakoids. The binding can be described by a simple isotherm with an apparent K_m = 4 μM and saturation at 1 neutral red per 17 chlorophylls. The apparent pK of neutral red is shifted from 6.6 in solution to 7.25 when bound inside. It is demonstrated that neutral red is a clean indicator of pH changes inside, i.e. when properly used it shows no response to other events. Although bound it reports pH changes which occur in the internal osmolar (aqueous) volume of thylakoids. This is obvious from the influence of chemically very different buffers on the magnitude of the absorption changes of neutral red. These act in a manner proportional to their calculated buffering capacity in aqueous solution. The intrinsic buffering capacity of the internal phase is determined with the aid of these buffers, at pH 7.2 it is between 0.8 and 1 mM (at 60 mosM). The absence of large variations in the buffering capacity in the range from pH 6.4 to 8.1 suggests that proteinaceous groups are involved in addition to the lipids which may dominate the buffering capacity at lower pH. The magnitude of the internal pH change is approx. 0.6 (at pH 7.3) under stimulation of both photosystems with a short xenon flash of light.     

Experience with an Image-Analyzing Computer in Virus Plaque Measurements

Due to the extremely fast and reliable plaque-number determinations, the image-analyzing computer is most useful for large screening programs involving plaque-reduction tests.     

pH-optima in lipase-catalysed esterification

Though lipases are frequently applied in ester synthesis, fundamental information on optimal pH or substrate concentration, can almost only be found for the reverse reaction - hydrolysis. This study demonstrates that the pH-optima of lipase-catalysed esterifications differ significantly from the optima of the hydrolysis reaction. In the esterification of n-butanol and propionic acid with lipases of Candida rugosa (CRL) and Thermomyces lanuginosa (TLL) pH-optima of 3.5 and 4.25, respectively, were found. This is about 3-4 units (CRL) and 7 units (TLL) in pH lower than optimum for hydrolysis. Enzyme activity increased with increasing concentrations of protonated acid indicating that the protonated acid rather than the deprotonated form is substrate for esterification. The rate of esterification can be drastically increased by ensuring acid concentrations up to 1000 mmol L^-1 for CRL and 600 mmol L^-1 for TLL in the reaction system.     

Generation of lipase-containing static emulsions in silicone spheres for synthesis in organic media

Because of the broad versatility of lipases as biocatalysts, interest has for some years been focused on the improvement of the economy of processes using these enzymes, especially by appropriate immobilisation. In this study, a method was developed to emulsify aqueous solutions of lipase A of Candida antarctica (CALA) and lipase of Thermomyces lanuginosa (TLL) in silicone elastomers yielding elastic beads. The persistent water-organic interface created by this static emulsion enabled an improved performance of the immobilised lipases due to the well known fact that from a kinetic point of view these enzymes show a higher efficiency in biphasic than in monophasic systems. The entrapped lipases catalysed the esterification of octanol and caprylic acid in hexane with an activity that, related to the free enzyme, was enhanced about 31-fold for CALA and 250-fold for TLL. Comparison to the activity of the same enzymes in sol–gels revealed that for CALA immobilisation in static emulsion was the only method yielding active biocatalysts, whereas activation of TLL was in the same range in static emulsion and sol–gels. However, apparent activity of TLL in static emulsion was considerably higher than in sol–gels due to the feasible high enzyme loading. The results indicate that immobilising lipases as static emulsion is a technique suitable for biotechnological application. Moreover, a transfer to enzymes of other classes seems possible.