The cortical response in Xenopus laevis ova

A dependence on extracellular calcium has been demonstrated for fertilization and the cortical response to pricking in Xenopus ova. Neither event occurred in calcium-free solutions or in the presence of divalent cation chelating agents. The calcium-sensitive phase of the cortical response to pricking in dejellied eggs was restricted to the 5–10 sec immediately following the activation stimulus; the initial phase of activation was not calcium dependent. In contrast, the cortical response in dejellied Xenopus ova exposed to the chemical activating agents, urethan or methyl urethan, was independent of extracellular calcium. Experimental evidence was presented for the involvement of a direct, nonpropagated cortical reaction in response to urethan stimulation as opposed to a propagated reaction in response to pricking. A cortical response in dejellied eggs was not induced spontaneously by high concentrations of potassium, and the prick response was unaffected by inhibitors of energy transfer processes. Molecular mechanisms operative in the initiation and propagation of the cortical response in animal eggs have been discussed.     

A versatile assay for total cellulase activity using U-[14C]-labelled bacterial cellulose

Summary A versatile and sensitive assay for total cellulase activity and not just carboxymethylcellulase activity, is described. The method is equally suitable for studying the kinetics of solubilization of cellulose by growing cells or isolated enzyme fractions.     

Reaction of methyl β-d-glycero-l-manno-heptopyranoside with cyclohexanone: Synthesis of the 4- and 6-methyl ethers of d-glycero-l-manno-heptitol

Acid-catalysed condensation of methyl β-d-glycero-l-manno-heptopyranoside with cyclohexanone yielded an approximately 3:1 mixture of the 2,3:6,7- and 2,3:4,7-di-O-cyclohexylideneheptosides (1 and 2), which could be separated either as their benzoates (3 and 4) or as their methyl ethers (5 and 6). The latter compounds afforded the 4- and 6-methyl ethers (7 and 8) of d-glycero-l-manno-heptitol.     

GRF-induced feeding: Evidence for protein selectivity and opiate involvement

Growth hormone-releasing factor (GRF) is a hypothalamic peptide named for its ability to induce release of growth hormone from the anterior pituitary. GRF also acts as a neurotransmitter in the suprachiasmatic nucleus/medial preoptic area (SCN/MPOA) to stimulate food intake. The purpose of this series of experiments was to explore the nature of GRF-induced feeding, with a particular emphasis on macronutrient selectivity, and to examine the role of opiate activity in the paraventricular nucleus of the hypothalamus (PVN). Chow intake stimulated by GRF microinjection (1 pmol/0.5 μl) into the SCN/MPOA was blocked by injection of methyl-naltrexone (3 μg/0.5 μl) into the PVN. In animals habituated to macronutrient diets (Teklad, WI), GRF preferentially stimulated intake of protein at 2 and 4 h postinjection, whereas it had no effect on carbohydrate intake. Further, this effect was blocked by injection of naloxone (40 nmol/0.5 μl) into the PVN. Microinjection of morphine (0, 1, 10, and 17 μg/0.5 μl) into the PVN also specifically stimulated protein intake at 2 and 4 h postinjection. These results suggest that feeding derived from GRF actions in the SCN/MPOA is macronutrient selective, and is dependent on PVN opiate activity for expression.     

Prognosis of non-Hodgkin's lymphomas in the Dresden district with special reference to combined radio-/chemotherapy

The total population affected with non-Hodgkin's lymphoma and treated by means of radiotherapy or combined radio-chemotherapy between 1960 and 1985 at the Medical Academy Dresden was analysed as to prognosis. 247 patients were classified according to the previous German scheme, 79 were subdivided on the basis of the recommendations laid down in the Kiel classification. The remission rates and survival curves achieved will stand out the comparison with international literature (remission rates of the low malignancy group amounted to 85.3 p.c. and those of the high malignancy group to 80.0 p.c.; the 5-years survival rates of the low malignancy group amounted to 61.9 p.c. and those of the high malignancy group to 41.7 p.c.). The influence of histology, clinical stage and involvement of organs is discussed on the basis of our results and informations obtained in literature. Our analysis confirms the high importance which must be attached to a common radiologic-internal outpatient-department for co-ordinating the diagnostic and therapeutical programme.     

Simplified procedure for measurement of serum dehydroepiandrosterone and its sulfate with gas chromatography–ion trap mass spectrometry and selected reaction monitoring

Dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) are endogenous steroids that have recently been widely publicized as potential treatments for many disorders. This paper describes a gas chromatographic–ion trap mass spectrophotometric assay with selected reaction monitoring for measurement of DHEA and DHEAS levels. The hormones and internal standard (5-androsten-3β-ol-16-one methyl ester) are extracted from serum with Oasis solid-phase extraction tubes. The extracted steroids are dissolved in methanol and injected into a Finnigan GCQ ion trap mass spectrometer. In the selected reaction mode, both DHEA and DHEAS can be identified and quantified in a single injection. No derivatization or expensive deuterated internal standards are required.     

Expression of renal cell protein markers is dependent on initial mechanical culture conditions.

The rotating wall vessel is optimized for suspension culture, with laminar flow and adequate nutrient delivery, but minimal shear. However, higher shears may occur in vivo. During rotating wall vessel cultivation of human renal cells, size and density of glass-coated microcarrier beads were changed to modulate initial shear. Renal-specific proteins were assayed after 2 days. Flow cytometry antibody binding analysis of vitamin D receptor demonstrated peak expression at intermediate shears, with 30% reduction outside this range. Activity of cathepsin C showed the inverse pattern, lowest at midshear, with twofold increases at either extreme. Dipeptidyl-peptidase IV had no shear dependence, suggesting that the other results are specific, not universal, changes in membrane trafficking or protein synthesis. On addition of dextran, which changes medium density and viscosity but not shear, vitamin D receptor assay showed no differences from controls. Neither cell cycle, apoptosis/necrosis indexes, nor lactate dehydrogenase release varied between experiments, confirming that the changes are primary, not secondary to cell cycling or membrane damage. This study provides direct evidence that mechanical culture conditions modulate protein expression in suspension culture.     

Auswirkungen der Methode der Linearisierung des μ-cs-Verlaufs auf die Parameteranpassung bei dem Monodschen Modell

Nowadays, the MONOD conception is the foundation for modelling the growth-connected substrat consumption. The methods of the parameter estimation for μ_max and K_s have a variable exactness. Using the experimental MONOD 's data [1] variable graphical and numerical methods are analyzed from the point of statistical view. Appropriate objective functions are proposed.