Structural changes in the sarcoplasmic reticulum membrane of skeletal muscles at the early stage of x-ray irradiation]

A single X-ray irradiation of the rabbit hindlimbs in a dose of 0.24 C/kg evokes a decrease in fluorescence of the ANS probe bound with membranes of the sarcoplasmatic reticulum as a result of the decrease of binding sites, binding constant as well as the quantum output of the probe. A decrease in fluorescence of tryptophan residues of Ca-ATPase localized in membranes and attenuation of interaction of its SH-group with dithionitrobenzoic acid has been also observed at early postradiation terms (1 and 24 h). The obtained results evidence for structural rearrangements occurring in membranes of the sarcoplasmic reticulum under the effect of ionizing radiation. Changes in conformation of CA-ATPase molecules contribute much to this process.     

Protocol of a prospective study on the diagnostic value of transcranial duplex scanning of the substantia nigra in patients with parkinsonian symptoms

Background  

Parkinson's disease (PD) is the second most common neurodegenerative disorder. As there is no definitive diagnostic test, its diagnosis is based on clinical criteria. Recently transcranial duplex scanning (TCD) of the substantia nigra in the brainstem has been proposed as an instrument to diagnose PD. We and others have found that TCD scanning of substantia nigra duplex is a relatively accurate diagnostic instrument in patients with parkinsonian symptoms. However, all studies on TCD so far have involved well-defined, later-stage PD patients, which will obviously lead to an overestimate of the diagnostic accuracy of TCD.     

Na+,K+-ATPase and Ca2+-ATPase isozymes in malignant neoplasms

A current state of researches on mechanisms of ion homeostasis regulation in the specific conditions of the uncontrolled malignant tumor growth (mainly in carcinomas) concerning the contribution of Na+,K+-ATPase, plasma membrane and sarco(endo)plasmic reticulum Ca2+-ATPases has been reviewed. Particular attention has been focused on the molecular and biochemical links providing the redistribution of the transporting ATPases isozyme pattern for the regulatory requirements of the cell signaling pathways at stable proliferation and viability in malignancy.     

Immunomorphological characteristics of experimental allergic encephalomyelitis induced by an encephalitogenic polypeptide

Encephalitogenic, immunogenic properties of the polypeptide fraction of myelin basic protein (FBP) and CNS lesions have been examined in animals with experimental allergic encephalomyelitis (EAE). FBP was isolated from bovine spinal cord using column chromatography. Administration of 1.0 or 0.1 microgram FBP mixed with complete Freund adjuvant caused neurological and histological EAE manifestations in 76% and 26% of guinea-pigs, respectively. Circulating anti-FBP antibodies were not found in sensitized animals, whereas the incidence and intensity of skin reaction of delayed type hypersensitivity to FBP correlated with the development of EAE and the onset of the disease. Perivascular cell infiltration and demyelination noted in the spinal cord and brain of guinea-pigs were similar to those observed after inoculation of the brain white matter or brain tissue homogenate.     

Immunomorphologic features of experimental allergic encephalomyelitis induced by the administration of tryptophan peptide

Three patterns of EAE with different morbidity and mortality rates were induced in the guinea pigs inoculated with various doses of tryptophane peptide (TP) and complete Freund's adjuvant. TP-sensitized animals manifested the delayed type hypersensitivity (DTH) reactions to TP and circulating anti-TP and -BPF antibodies were not found, polypeptide fraction of myelin basic protein (BPF while a A correlation was revealed between the DTH-reactions and EAE development. Intracutaneous TP and BPF injections at the early period before the EAE onset resulted in reduction of morbidity rate from 90 to 50 per cent. For the first time with the help of modified Marchi method demyelination has been shown to be highly marked in CNS tissue process in CNS can be caused by cell-mediated immune of animals given TP. It is supposed that the demyelinating reaction to encephalitogenic fragment of BP molecule. The data indicate a possibility of EAE inhibition by means of TP and BPF injections in saline solution.     

The conduction of protons in different stereoisomers of dioxolane-linked gramicidin A channels

Two different stereoisomers of the dioxolane-linked gramicidin A (gA) channels were individually synthesized (the SS and RR dimers;. Science. 244:813-817). The structural differences between these dimers arise from different chiralities within the dioxolane linker. The SS dimer mimics the helicity and the inter- and intramolecular hydrogen bonding of the monomer-monomer association of gA's. In contrast, there is a significant disruption of the helicity and hydrogen bonding pattern of the ion channel in the RR dimer. Single ion channels formed by the SS and RR dimers in planar lipid bilayers have different proton transport properties. The lipid environment in which the different dimers are reconstituted also has significant effects on single-channel proton conductance (g(H)). g(H) in the SS dimer is about 2-4 times as large as in the RR. In phospholipid bilayers with 1 M [H(+)](bulk), the current-voltage (I-V) relationship of the SS dimer is sublinear. Under identical experimental conditions, the I-V plot of the RR dimer is supralinear (S-shaped). In glycerylmonooleate bilayers with 1 M [H(+)](bulk), both the SS and RR dimers have a supralinear I-V plot. Consistent with results previously published (. Biophys. J. 73:2489-2502), the SS dimer is stable in lipid bilayers and has fast closures. In contrast, the open state of the RR channel has closed states that can last a few seconds, and the channel eventually inactivates into a closed state in either phospholipid or glycerylmonooleate bilayers. It is concluded that the water dynamics inside the pore as related to proton wire transfer is significantly different in the RR and SS dimers. Different physical mechanisms that could account for this hypothesis are discussed. The gating of the synthetic gA dimers seems to depend on the conformation of the dioxolane link between gA's. The experimental results provide an important framework for a detailed investigation at the atomic level of proton conduction in different and relatively simple ion channel structures.