Plant regeneration from protoplasts of the monocotyledonous Haworthia magnifica v. Poelln.

Calli were initiated from flower buds, gynoecia and inflorescence segments of Haworthia magnifica v. Poelln. and subcultured on solid medium. Two liquid culture steps were necessary to prepare the calli for the isolation of protoplasts capable of sustained cell divisions. Plants were regenerated from protoplast-derived calli. The influence of both the osmolality of the culture media and exudates on the viability of protoplasts and protoplast-derived cell colonies is briefly discussed.     

Cell cycle effects of an autologous growth promoter from human leukemia cells

The mechanism of action of an autologous growth promoter, produced by HL-60 cells grown in serum-free defined medium, was investigated. Determinations of cell cycle phase distribution, which showed an approx. 16% increase in S and G2M with a reciprocal decrease in G1 cells, indicated a mechanism causing decreased time in G1, resulting in a more rapid entry of cells into G2M. Adsorption of the culture supernatant with HL-60 cells resulted in a decreased promoter activity, suggesting an autologous receptor mechanism for the promoter.     

Ein Regelwerk für paläontologische Grabungen in der Grube Messel

The “Framework Messel” formulates regulations, recommendations and instructions for planning and carrying out palaeontological excavations in the Messel pit. The excavation of fossils in the Land Hessen is to some extent controlled by the Monument Protection Law. Therefore, the Framework was developed in close cooperation with the Land Monument Office. Administrative, scientific and organizational conditions for the excavations in the Middle Eocene oil-shales of Messel are listed. Instructional pamphlets explain technical details regarding methods of documentation, excavation and preparation of finds and results.     

On peptide bond formation, translocation, nascent protein progression and the regulatory properties of ribosomes. Derived on 20 October 2002 at the 28th FEBS Meeting in Istanbul.

High-resolution crystal structures of large ribosomal subunits from Deinococcus radiodurans complexed with tRNA-mimics indicate that precise substrate positioning, mandatory for efficient protein biosynthesis with no further conformational rearrangements, is governed by remote interactions of the tRNA helical features. Based on the peptidyl transferase center (PTC) architecture, on the placement of tRNA mimics, and on the existence of a two-fold related region consisting of about 180 nucleotides of the 23S RNA, we proposed a unified mechanism integrating peptide bond formation, A-to-P site translocation, and the entrance of the nascent protein into its exit tunnel. This mechanism implies sovereign, albeit correlated, motions of the tRNA termini and includes a spiral rotation of the A-site tRNA-3' end around a local two-fold rotation axis, identified within the PTC. PTC features, ensuring the precise orientation required for the A-site nucleophilic attack on the P-site carbonyl-carbon, guide these motions. Solvent mediated hydrogen transfer appears to facilitate peptide bond formation in conjunction with the spiral rotation. The detection of similar two-fold symmetry-related regions in all known structures of the large ribosomal subunit, indicate the universality of this mechanism, and emphasizes the significance of the ribosomal template for the precise alignment of the substrates as well as for accurate and efficient translocation. The symmetry-related region may also be involved in regulatory tasks, such as signal transmission between the ribosomal features facilitating the entrance and the release of the tRNA molecules. The protein exit tunnel is an additional feature that has a role in cellular regulation. We showed by crystallographic methods that this tunnel is capable of undergoing conformational oscillations and correlated the tunnel mobility with sequence discrimination, gating and intracellular regulation.     

Biphasic 24-Hour Variations in Cyclic GMP Accumulation in the Rat Pineal Gland Are Due to Corresponding Changes in the Activity of Cytosolic and Particulate Guanylate Cyclase

Various parameters of the rat pineal gland display a 24-h rhythm. However, nothing is known about possible 24-h variations in cyclic GMP (cGMP) metabolism. In the present study, 24-h variations in pineal gland cGMP accumulation were investigated by determining the increase in cGMP level with and without inhibitors of phosphodiesterase at different time points over a light/dark cycle (12/12 h). Furthermore, the activity of guanylate cyclase (GC) was determined under substrate-saturated conditions regarding the cytosolic and particulate forms of the enzyme. It has been found that cGMP accumulation and GC activity display biphasic 24-h variations with two peaks--one approximately 7 h after lights "on" and the other approximately 7 h after lights "off." The activity of cytosolic GC remains unchanged in the presence of the nitric oxide (NO) synthesis inhibitor N-monomethyl-L-arginine, indicating that 24-h variations in the activity do not reflect changes in the synthesis of the GC stimulator NO.     

Extended somatostatin treatment of a patient with bleeding ulcer.

The results of a 67 hour cyclic somatostatin continuous infusion in a patient with a bleeding ulcer are reported. The subject was a 65 year old male with very heavy gastrointestinal bleeding on the 9th postoperative day following a high BI-resection. Endoscopy revealed the bleeding to be caused by two residual ulcers in the area of the anastomosis. Somatostatin treatment led to an immediate cessation of the bleeding after 1 hour. Gastric secretion as well as gastrin, insulin and growth hormone levels were significantly inhibited by somatostatin. Endoscopy at the end of the treatment period showed two ulcers in the process of healing. The raised blood glucose levels caused by somatostatin were easily controlled with max. 14 IU cristalline insulin daily. Except for dryness in the mouth, no adverse side effects were apparent. There was no evidence from laboratory investigations of hemostatic defects or bleeding tendency in the patient.