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Biomedical subjects

D Vogel

Publications and source records attributed to D Vogel.

54 records · Page 3Linked to original sources
PubMed1977

Hydrogen-ion binding by tobacco-mosaic-virus protein polymers.

Hydrogen ion titration curves of tobacco mosaic virus protein have been measured in various conditions of protein concentration, temperature, ionic strength, and rate of pH change. The polymers present at each stage are deduced from turbidity and sedimentation data, plus published information. A simple semi-quantitative analysis of the curves is given, and the pK values of the two abnormal carboxylates in single helix are estimated as 6.4 and about 7.0. Disks, and some faster-forming unknown polymers in the same size range, have been abnormal carboxylate with pK 6.9. These results are most easily interpreted in terms of electrostatic interactions between carboxylates, probably at the axial ends of the protein subunits.

Hydrogen-Ion Concentration↗
PubMed1976

Circular-dichroism and absorption spectroscopic studies on specific aromatic residues involved in the different modes of aggregation of tobacco-mosaic-virus protein.

Conformational changes accompanying the different modes of aggregation of tobacco mosaic virus protein (TMV-protein) were investigated using circular dichroism (CD) and absorption difference spectra in the range of aromatic absorption. Comparing wild-type protein and mutant Ni 2068 (Tyr-139 leads to Cys-139) a tentative localization of aromatic amino acids in the three-dimensional structure is rendered possible. In all modes of aggregation the CD spectra are determined by intrasubunit interactions between aromatic residues, in particular Trp-17 and Trp-52 as well as Tyr-70, Tyr-72 and Tyr-139. The Trp-17-Trp-52 interaction was found to be highly sensitive towards changes of the quaternary structure especially with respect to helical aggregates. This suggests that the environment of the two tryptophan residues is of crucial importance in the three-dimensional structure of the subunit; in the course of aggregation intersubunit interactions compete with the specific intrasubunit Trp-17--Trp52 interactions. It is suggested that Try-70 and Tyr-72 form hydrogen bonds in a strongly hydrophobic environment. Formation of the double disc decreases the rotatory strength, pointing to an increase in conformational flexibility. Spectroscopic and chemical evidence prove that Tyr-70, Tyr-72 and Tyr-139 are in close neighbourhood. Double disc formation by lowering the pH (pH 8 LEADS TO 6.9, I = 0.1 M) or increasing the ionic strength (pH 8, I = 0.1 LEADS TO 0.6 M) is reflected by identical spectral effects in the environment of Tyr-70 - Tyr-72. However the interaction between Trp-17 and Trp-52 indicates significant differences in the conformation which may be important for the formation of higher aggregates, i.e. 'lockwashers', helices, and 'stacked discs'.

Binding Sites↗
PubMed1975

[Therapy of the bronchitic syndrome (author's transl)].

The bronchitic syndrome necessitates chemotherapeutic management, especially in view of the secondary complications arising in this condition. Chemotherapy must be consistently adhered to, not only during acute exacerbations, but also during the relatively symptom-free intervals between exacerbations and also in those cases displaying minimal symptomatology. A useful criterion of the necessity for chemotherapy is the presence of a purulent sputum and with the appearance of this feature, specific chemotherapy should be initiated without delay (W. T. Ulmer). Appropriate investigations in 41 patients showed that Lidaprim, a combined preparation of trimethoprim and sulfametrol, can be recommended on the basis of its beneficial chemotherapeutic effect, good tolerability and simplicity of administration. Purulence of the sputum disappeared within 10 days of commencement of treatment with 2 times 2 tablets Lidaprim daliy in 38 out of the 41 patients. The clinical symptoms, including respiratory difficulties, improved simultaneously with the decrease in quantity of expectorated sputum. Lidaprim represents a useful and effective chemotherapeutic agent in the hands of both the hospital specialist and the general practitioner for treatment of the bronchitic syndrome in all its diverse forms.

Adult↗
PubMedDate not supplied

Behavioral discrimination of water motions caused by moving objects.

We tested whether goldfish, Carassius auratus, discriminate hydrodynamic stimuli caused by moving objects. Blindfolded goldfish responded to a passing object with changes in inter-gill-movement intervals. To learn whether goldfish can discriminate water motions caused by different moving objects we habituated them to a certain object stimulus. If the stimulus was altered, e.g., by altering speed, direction of motion, or size or shape of the object, fish again showed a temporary suspension of breathing when the object passed by. If animals failed to respond to an altered stimulus, we paired this stimulus with a weak electric shock during training. Goldfish discriminated object motion direction. In addition, in two choice experiments goldfish discriminated water motions caused by objects which moved with different speeds (e.g., 5 cm s(-1) versus 6 cm s(-1)), or by objects which differed in size (e.g., 1 cm x 1 cm versus 1.4 cm x 1.4 cm cross section), or shape (e.g., a round versus a triangular object). If object size and/or shape was varied quasi-randomly such that the faster moving object not always caused the greatest water velocities, fish still discriminated object speed.

Animals↗
PubMedDate not supplied

Neuronal transmission of hippocampal CA1 neurones is modulated by corticotropin-like intermediate lobe peptide [CLIP; ACTH(18-39)].

The study was conducted to test whether CLIP [ACTH(18-39)] influences the neuronal transmission and the induction of long-term potentiation (LTP) in the hippocampus. The population spike was recorded in the hippocampal CA1 region of freely moving rats before and after intracerebroventricular (ICV) administration of CLIP in comparison to ACTH and saline (controls). After infusion of CLIP, the population spike amplitude (PSA) rose to about 200% of baseline values. After reaching this level, it was impossible to induce a further increase of PSA by tetanization. However, if the stimulus intensity was reduced to a new baseline level, electrically induced LTP could be observed. There were no significant changes after infusion of ACTH. Our results indicate that the ICV administration of CLIP leads to an enhancement of excitability in the hippocampal CA1 region, which might be independent of LTP.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

[From foreign worker to pensioner--selected aspects of financial security and social care of elderly foreigners in Germany].

There is evidence that many older migrants of foreign nationality remain permanently in the Federal Republic of Germany. Therefore the question of their social protection after retirement arises. This contribution discusses the financial protection via statutory pensions and social assistance, as well as the care provided by their families or on an inpatient or outpatient basis. Deficits in social protection of older immigrants are evident, which should be investigated more thoroughly and dealt with by social policy.

Aged↗