Probing the photoreaction mechanism of phytochrome through analysis of resonance Raman vibrational spectra of recombinant analogues.

Resonance Raman spectra of native and recombinant analogues of oat phytochrome have been obtained and analyzed in conjunction with normal mode calculations. On the basis of frequency shifts observed upon methine bridge deuteration and vinyl and C(15)-methine bridge saturation of the chromophore, intense Raman lines at 805 and 814 cm(-)(1) in P(r) and P(fr), respectively, are assigned as C(15)-hydrogen out-of-plane (HOOP) wags, lines at 665 cm(-)(1) in P(r) and at 672 and 654 cm(-)(1) in P(fr) are assigned as coupled C=C and C-C torsions and in-plane ring twisting modes, and modes at approximately 1300 cm(-)(1) in P(r) are coupled N-H and C-H rocking modes. The empirical assignments and normal mode calculations support proposals that the chromophore structures in P(r) and P(fr) are C(15)-Z,syn and C(15)-E,anti, respectively. The intensities of the C(15)-hydrogen out-of-plane, C=C and C-C torsional, and in-plane ring modes in both P(r) and P(fr) suggest that the initial photochemistry involves simultaneous bond rotations at the C(15)-methine bridge coupled to C(15)-H wagging and D-ring rotation. The strong nonbonded interactions of the C- and D-ring methyl groups in the C(15)-E,anti P(fr) chromophore structure indicated by the intense 814 cm(-1) C(15) HOOP mode suggest that the excited state of P(fr) and its photoproduct states are strongly coupled.

Three-dimensional structure of the human TFIID-IIA-IIB complex.

The multisubunit transcription factor IID (TFIID) is an essential component of the eukaryotic RNA polymerase II machinery that works in concert with TFIIA (IIA) and TFIIB (IIB) to assemble initiation complexes at core eukaryotic promoters. Here the structures of human TFIID and the TFIID-IIA-IIB complex that were obtained by electron microscopy and image analysis to 35 angstrom resolution are presented. TFIID is a trilobed, horseshoe-shaped structure, with TFIIA and TFIIB bound on opposite lobes and flanking a central cavity. Antibody studies locate the TATA-binding protein (TBP) between TFIIA and TFIIB at the top of the cavity that most likely encompasses the TATA DNA binding region of the supramolecular complex.

Resonance raman analysis of chromophore structure in the lumi-R photoproduct of phytochrome.

Resonance Raman vibrational spectra of the Pr, lumi-R, and Pfr forms of phytochrome have been obtained using low-temperature trapping and room temperature flow techniques in conjunction with shifted-excitation Raman difference spectroscopy (SERDS). The Pr to lumi-R photoconversion exhibits a thermal barrier and is completely blocked at 30 K, indicating that thermally assisted protein relaxation is necessary for the primary photochemistry. When Pr is converted to lumi-R, new bands appear in the C = C and C = N stretching regions at 1651, 1636, 1590, and 1569 cm-1, indicating that a significant structural change of the chromophore has occurred. The photoconversion also results in an 18 cm-1 decrease in the N-H rocking band in lumi-R. Normal mode calculations correlate this frequency drop with a change in the geometry of the C15 methine bridge of the phytochromobilin chromophore. Additionally, a C = N stretching mode marker band shifts from 1576 cm-1 in Pr to 1569 cm-1 in lumi-R and to 1552 cm-1 in Pfr. Normal mode calculations show that the frequency drop of this band in the lumi-R-->Pfr interconversion is an indication of a C14-C15 syn-->anti conformational change. Moderately intense hydrogen out-of-plane modes that occur at 805 cm-1 in Pr shift to 829 and 847 cm-1 upon photoconversion to lumi-R and are replaced by a very intense mode at 814 cm-1 in Pfr. These observations indicate that the C and D rings of the chromophore in Pr and lumi-R are moderately planar but that they become highly distorted in Pfr. This information suggests that the primary photochemistry in phytochrome is a Z-->E isomerization of the C15 = C16 bond of Pr giving lumi-R. This is followed by a thermal syn-->anti C14-C15 conformational relaxation to form Pfr. A four-state model is presented to explain the chromophore structural changes in Pr, lumi-R, and Pfr that uses hydrogen bonding to the surrounding protein to stabilize the high-energy Pfr C15 = C16, C14-C15, E,anti chromophore structure. This implicates an anchor and release mechanism between the chromophore and protein that might lead to altered biological signaling in the plant.

[Does self involvement promote self medication? A comparative study of 6 countries of the European community]. / Fördert die Selbstbeteiligung die Selbstmedikation? Eine Vergleichsstudie in sechs Ländern der Europäischen Gemeinschaft.

Discussing cost-sharing in health care as a means to arrive at certain cost retrenchments is nowadays a popular topic in Switzerland. This also holds true for patient part-payment of medicines, through which the level of reimbursement of prescription medicines by sick-funds may be decreased. This paper reviews recent changes in the patient part-payment system for drugs in 6 countries of the European Community. It is investigated whether the rate of self-medication increases, when patient part-payment systems for drugs are intensified. Especially the English situation seems to prove the validity of this correlation. However, one should be cautious, because many other factors--such as whether a medicine has a prescription-only status or not--may also play a prominent role.

The legal mandate of drug registration authorities in theory and practice.

In the course of this century all industrial nations witnessed a growth in the influence of the state over the individual. Usually, state intervention in private life is justified by the state's mandate to protect the health and security of its constituents, either through general, uniform precepts such as laws or decrees, or through individual arrangements such as licences or subsidies. The principle of state protection has also long been established in the pharmaceutical sector, and entails that regulatory agencies should only approve those drugs for market use, which--according to scientific knowledge--have benefits which outweigh their potential harmful effects. Although 'the state of scientific knowledge' seems to imply that safety decisions concerning drugs are predominantly based on medical, scientific criteria, it is argued in this paper, that regulatory agencies nevertheless have wide discretionary margins, which allow for a political dimension to such decisions. For this reason it is briefly examined how drug authorities react under political pressure, i.e. when a drug has become a public problem. Additionally, the issue is considered why especially so-called non-steroidal anti-inflammatory drugs (NSAID's) have recently been the focus of controversy in the media. This attention has led to a situation in which it seems that regulatory agencies only accept drugs for market use with zero risk. The paper concludes by recommending that safety decisions of health authorities should involve two expert levels: in order to make precise risk assessments on the scientific level all relevant information about risks and benefits of drugs should be collated, whereas safety decisions should be taken by experts knowledgeable in the field of societal proportions.

On regulating perceived risk.

Modern society increasingly depends on government regulation to manage risks. Until recently, evaluation of risks of technology was primarily considered a technical problem. However, public controversy has politicized the issue of risk, raising questions about the role of experts. This paper briefly explores the nature of technical risks of aircraft, nuclear energy and medicines. It is contended that in the case of aircraft intensive regulation has led to a measurable improvement of its safety record. The constant call for more regulation in the areas of medicines and nuclear energy on the other hand seems more the result of public controversy, since the actual effect of regulatory measures on safety is too difficult to show. This stresses the important role of the media, a theme, which is elaborated by reviewing a number of cases. The general conclusion is concerned with the notion that public pressure is the only rationale which makes regulators step in. Regulatory decision-making about risk, then, is more anecdotal than systematic, because public controversy is unpredictable. As a consequence regulators can no longer seek to minimize harm, but must now move towards the aim of minimizing perceived harm. Finally, in the light of this assumption, some thought is given to costs and benefits of medicines and nuclear energy. It is appropriate to make a strong case for medicines in this context, for, as opposed to nuclear energy, alternatives are usually not available.