Zum Histochemischen Nachweis Der Aldehyd-Dehydrogenase

Zusammenfassung Es wird eine Methode zum histochemischen Nachweis der Aldehyd-Dehydrogenase beschrieben. Das Inkubationsgemisch setzt sich folgendermaßen zusammen: Phosphatpuffer, 0,06 m, pH 7,0, 8,0 ml; NaN₃ in 0,06 m Phosphatpuffer, pH 7,0, 0,1 m, 1,0 ml; Acetaldehyd, 1,0 m, 1,0 ml; Nitro-BT, 2,5 mg; MgCl₂·6H₂O, 10 mg; NAD, 11 mg. Tris erwies sich zur Pufferung des Inkubationsgemisches als ungeeignet, weil die Aminogruppe der Puffersubstanz mit der Carbonylgruppe des Acetaldehyds zu einem Azomethin reagiert. Dadurch kommt es zur Änderung des pH-Wertes und zur Erniedrigung der Substratkonzentration. KCN sollte zur Blockierung der Atmungskette bei diesem Nachweis nicht angewendet werden, da infolge Cyanhydrinbildung ebenfalls die Substratkonzentration vermindert wird.

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Summary A method is described for the histochemical determination of aldehyde dehydrogenase. The incubation medium contains: phosphate buffer, 0.06 m, pH 7.0, 8.0 ml; NaN₃ in 0.06 m phosphate buffer, pH 7.0, 0.1 m, 1.0 ml; acetaldehyde, 1.0 m, 1.0 ml; Nitro-BT 2.5 mg; MgCl₂·6H₂O, 10 mg; NAD, 11 mg. Tris is not suitable as a buffer as the amino group of the buffer substance combines with the carbonyl group of the acetaldehyde to form azomethine. The consequence is a change in the pH value and a decrease in the concentration of the substrate. KCN should not be used to block the respiratory chain as it also influences the concentration of the substrate through the formation of cyanhydrin.

     

The effect of raphe nuclei lesions on the rat ovarian cycle

The effects of lesions of the median raphe or dorsal raphe nuclei on ovarian cycle were studied in rats. Lesions involving raphe nuclei decreased forebrain 5-HT and 5-hydroxyindole acid (5-HIAA) concentrations. Rats with lesions of the raphe showed prolonged estrous phase as well as an increase in both the eosinophilic index and karyopycnotic index of the vaginal smears. Histological examinations revealed that lesions of both the dorsal and median raphe produced marked increase in the number of maturing and mature follicles as well as an increase in corpora lutea. The increase in uterine weight was also observed. Present results indicate that lesions of the ascending 5-HT neurons stimulate ovulation and cause an increase in the estrogenic activity. Thus, the 5-HT neurons of the raphe nuclei seem to inhibit ovulation probably due to inhibiting of the hypothalamic releasing hormones.     

Various characteristics of intravenous polyvalent immunoglobulins

Polyvalent human immunoglobulins for intravenous use (GVP) are obtained by fractionating human plasma with ethanol, according to a method in which traces of pepsin at pH4 eliminate any anticomplementary activity. All the analytical tests have come within official requirements. Results of extended tests concerning specificity, potency, immunoglobulin subclass distribution, biological half-life and opsonic function are presented. Since their official release for clinical use on July 1st, 1983, almost 15,000 therapeutic units of 2.5 g of immunoglobulins have been consumed without any reported major side effects. Multicenter clinical trials are being carried out with adults and children. Available results confirm very good tolerance, and, as expected, effectiveness for well known and codified indications.     

A model-based framework for parallel scale-down fed-batch cultivations in mini-bioreactors for accelerated phenotyping

Concentration gradients that occur in large industrial-scale bioreactors due to mass transfer limitations have significant effects on process efficiency. Hence, it is desirable to investigate the response of strains to such heterogeneities to reduce the risk of failure during process scale-up. Although there are various scale-down techniques to study these effects, scale-down strategies are rarely applied in the early developmental phases of a bioprocess, as they have not yet been implemented on small-scale parallel cultivation devices. In this study, we combine mechanistic growth models with a parallel mini-bioreactor system to create a high-throughput platform for studying the response of Escherichia coli strains to concentration gradients. As a scaled-down approach, a model-based glucose pulse feeding scheme is applied and compared with a continuous feed profile to study the influence of glucose and dissolved oxygen gradients on both cell physiology and incorporation of noncanonical amino acids into recombinant proinsulin. The results show a significant increase in the incorporation of the noncanonical amino acid norvaline in the soluble intracellular extract and in the recombinant product in cultures with glucose/oxygen oscillations. Interestingly, the amount of norvaline depends on the pulse frequency and is negligible with continuous feeding, confirming observations from large-scale cultivations. Most importantly, the results also show that a larger number of the model parameters are significantly affected by the scale-down scheme, compared with the reference cultivations. In this example, it was possible to describe the effects of oscillations in a single parallel experiment. The platform offers the opportunity to combine strain screening with scale-down studies to select the most robust strains for bioprocess scale-up.     

Spider silks from plants – a challenge to create native-sized spidroins

Silk threads from spiders exhibit extraordinary mechanical properties, such as superior toughness and elasticity. Spider silks consist of several different large repetitive proteins that act as the basic materials responsible for these outstanding features. The production of spider silk protein variants in plants opens up new horizons in the production and functional investigation that enable the use of spider silks in innovative material development, nanotechnology and biomedicine in the future. This review summarizes and discusses production of spider silk protein variants in plants, especially with regards to plant expression systems, purification strategies, and characteristics of spider silk variants. Furthermore, the challenge of producing native-sized recombinant spidroins in planta is outlined, presenting three different strategies for achieving these high repetitive proteins with the help of non-repetitive C-terminal domains, crosslinking transglutaminase, and self-linking inteins. The potential of these fascinating proteins in medicine is also highlighted.     

Erwiederung

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