Physiological chemistry and physics最新文献

The polymeric prostaglandin, PGBX, has a beneficial effect on oxidative phosphorylation of damaged mitochondria in vitro and has manifested interesting effects in vivo. Its chemical structure has been partially elucidated by comparison of its 13C-NMR (nuclear magnetic resonance) spectrum with the spectra of prostaglandin monomers. Reported here is subsequent comparison of PGBX with two prostaglandin dimers derived from 15-keto-PGB1, which provide more complete structural information. The two prostaglandin dimers were synthesized and analyzed by 13C-MNR and by other techniques, with particular attention to positions of linkages between the two monomeric prostaglandin subunits of the dimers. Based on these data, some proposals are presented regarding probable locations of linkages between prostaglandin monomeric subunits in the polymeric PGBX.

High frequency electromagnetic fields are used currently in clinical therapy of cancer. A considerable research effort is spent on improving field application techniques. The main difficulty encountered is the establishment of a sufficient temperature difference between normal and cancerous tissue for effective therapy. Therefore I propose a temperature cycling technique in field applications which should permit achieving higher temperatures in the tumor region while temperatures in normal tissue remain within a physiological range. It is expected that by this technique an improvement in cancer cure rate could be obtained.

During in vitro investigation of changes in mitochondrial function accompanying lipid peroxidation, it was found that cepharanthine, a biscoclaurin alkaloid, protects against such change. Results obtained were as follows: (1) Fe2+ induces lipid peroxidation of isolated mitochondria, resulting in diminished oxidative phosphorylation. (2) This diminishment largely depends on deterioration of ion compartmentation of the membrane and an increase in latent ATPase activity. (3) The Fe2+-induced deterioration in ion compartmentation is inhibited by cepharanthine. (4) Cepharanthine inhibits the mitochondrial lipid peroxidation induced by Fe2+. (5) Cepharanthine inhibits the lipid peroxidation of soybean lecithin liposomes by 60Co-irradiation.

The concept of coherent electronic states and coherent interactions in supramolecular structures is applied to the process of genetic information coding and its transcription from DNA to mRNA. A new genetic code is proposed based on the assumption of coherent electron states in linear chains of nucleotide bases. A new interpretation of codon equivalency (redundancy) is given. The number of existing amino acids is derived from the optimalization principle applied to the physical system storing the genetic information in the new code. The proposed code uses a variable number of positions or nucleotide bases along the DNA-mRNA structure to code a single amino acid in a protein. The average of this variable number must be equal to the base of natural logarithms (e = 2.7 . . .) in order to minimize the number of nucleotides required to code a sequence of amino acids.

A probable structure for the best tricyclic antidepressant with respect to inhibition of reuptake of norepinephrine into peripheral adrenergic nerve terminals has been reported. Using tha result as indicating the particular conformation in which the tricyclic antidepressant is likely to mimic the biogenic amine at the membrane "pump" receptor site, the topography of the receptor surface has been worked out by simulating space-filling models of the best inhibitors of the two types in the superposed state. With appropriate computer graphic facilities such surfaces can be used to screen other untested molecules and to predict their activity.

Several lines of evidence suggest the involvement of bioelectronic mechanisms in brain function. Although no components of such mechanisms have been identified, neuromelanin is a likely candidate. The functional significance of neuromelanin is supported by considerable published work, herein reviewed. Certain electronic properties of melanin, notably in stable free radical characteristics and its semiconduction, may be influenced by alpha-MSH, ACTH 4-10, and melatonin. Neuron function may be influenced in turn by the effect of semiconduction on synaptic transmission. Thus neuromelanin may be an important part of a complex neural modulation system.

Cysteamine, a radioprotector belonging to the aminothiol class, interacts with nucleus DNA of mammalian or human cells to reduce the lethal effect of ionizing radiation. The transfer of this drug through cellular membranes has been studied, using as a model system an aqueous dispersion of lipid and cysteamine. The interaction of synthetic lecithin dipalmitoylphosphatidylcholine (DPPC) smectic mesophases with cysteamine was investigated by means of spectrophotometric and dielectric measurements. The thermal transitions of DPPC studied by spectrophotometry and dielectric Arrhenius diagrams showed that cysteamine deletes the pretransition of the lipid phase and does not modify the principal transition. This indicates a direct interaction between the lipid polar head with cysteamine; the aliphatic chains are not affected. Conductivity measurements confirmed these results and demonstrated an electrostatic interaction between the anionic phosphate site of the polar head and the cysteamine cation.

Electron spin resonance measurements are presented for the separated structural and soluble components of a variety of both normal and cancerous tissues. The signal at g = 2 from the structural part of the normal tissues was at least an order of magnitude stronger than the corresponding signal from the structural part of the cancers. In contrast, no significant difference in radical concentration was found between the soluble fractions of normal and cancerous tissues. Despite their common low signal at g = 2, the structural cancer fractions displayed a remarkable chemical heterogeneity. An important finding was that even cancers of the same histology reacted differently from one another when treated with a variety of chemical probes.

We have investigated the effects of chlorpheniramine (an H1 histamine inhibitor) and metiamide (an H2 inhibitor) on response to 14C pulse-labeling of carbon dioxide in the rat in the presence and absence of histamine. Neither chlorpheniramine nor metiamide alone had any effect upon the gastric venous/arterial ratio (VG/A) or the peripheral venous/arterial ratio (Vp/A). As in the case with no drug present, Vp/A rose with time following pulse-labeling to a value of 1.15-1.20. The presence of a preexisting steady-state infusion of histamine caused no changes in the ratios in the presence or absence of the inhibitors. The inhibitors did completely abolish the oscillations of both VG/A and Vp/A caused by initiation of histamine infusion coincident with the pulse-labeling. The results suggest that the histamine effects are largely mediated through H1 receptors.