Mechanical and signaling responses of unloaded rat soleus muscle to chronically elevated ß-myosin activity.

It has been reported that muscle functional unloading is accompanied by an increase in motoneuronal excitability despite the elimination of afferent input. Thus, we hypothesized that pharmacological potentiation of spontaneous contractile soleus muscle activity during hindlimb unloading could activate anabolic signaling pathways and prevent the loss of muscle mass and strength. To investigate these aspects and underlying molecular mechanisms, we used ß-myosin allosteric effector Omecamtiv Mekarbil (OM). We found that OM partially prevented the loss of isometric strength and intrinsic stiffness of the soleus muscle after two weeks of disuse. Notably, OM was able to attenuate the unloading-induced decrease in the rate of muscle protein synthesis (MPS). At the same time, the use of drug neither prevented the reduction in the markers of translational capacity (18S and 28S rRNA) nor activation of the ubiquitin-proteosomal system, which is evidenced by a decrease in the cross-sectional area of fast and slow muscle fibers. These results suggest that chemically-induced increase in low-intensity spontaneous contractions of the soleus muscle during functional unloading creates prerequisites for protein synthesis. At the same time, it should be assumed that the use of OM is advisable with pharmacological drugs that inhibit the expression of ubiquitin ligases.

[Photoinduced production of reactive oxygen species by retinal derivatives and conjugates].

The formation of reactive oxygen species (ROS) during all trans-retinal illumination was studied by ESR. The quantity of ROS was estimated by the ESR signal of a spin adduct of DEPMPO (5-dietoxyphosphoryl-5 methyl-1-pirroline-N-oxide). The ESR signal was found to be a superposition of the adducts: 80%--superoxide anion radical, 15%--hydroxyl radical and 5%--an unknown radical. It was shown that the addition of an equimolar albumin concentration resulted in the 5-fold decrease of the relative quantum yield for ROS generation, and a 4-fold albumin excess led to decreased ROS production by 30-fold. It is supposed that ATR and A2E in the photoreceptor membrane are the sources of photodamage induced by ROS. ATR in the cell is known to be transported by interphotoreceptor retinal binding proteins that belong to the albumin family. The ATR binding with proteins is supposed to prevent the ROS production in the photoreceptor cell and thus produces the light damage protection action.

Role of NO-synthase in regulation of protein metabolism of stretched rat m. soleus muscle during functional unloading.

Gravitational unloading causes atrophy of muscle fibers and can lead to destruction of cytoskeletal and contractile proteins. Along with the atrophic changes, unloaded muscle frequently demonstrates significant shifts in the ratio of muscle fibers expressing fast and slow myosin heavy chain isoforms. Stretching of the m. soleus during hindlimb suspension prevents its atrophy. We supposed that neuronal NO-synthase (NOS) (which is attached to membrane dystrophin-sarcoglycan complex) can contribute to maintenance of protein metabolism in the muscle and prevent its atrophy when m. soleus is stretched. To test this hypothesis, we used Wistar rats (56 animals) in experiments with hindlimb suspension during 14 days. The group of hindlimb suspended rats with stretched m. soleus was injected with L-NAME to block NOS activity. We found that m. soleus mass and its protein content in hindlimb-suspended rats with stretched m. soleus were preserved due to prevention of protein degradation. NOS is involved in maintenance of expression of some muscle proteins. Proliferation of satellite cells in stretched m. soleus may be due to nNOS activity, but maintenance of muscle mass upon stretching is regulated not by NOS alone.

[Modification of the nitric oxide concentration regulates the development of the apoptosis in the eye retina].

Using model elaborated it was shown that the retinal ischemia initiated the development of the apoptosis in the inner layers of the retina. Administration of NOS inhibitor prevented the development of the apoptosis in the retina. To ascertain if nitric oxide could induce the retinal apoptosis by itself the nontoxic donor of nitric oxide (dinitrosyl iron complex) was injected intravitreally. Administration of DNIC in low concentrations induced the development of the apoptosis in the same retinal layers as in ischemia. The injection of dinitrosyl iron complex at the higher concentration resulted in the decrease of the apoptosis level. Administration of dinitrosyl iron complex with excess of glutathione didn't lead to the development of the retinal apoptosis. The obtained data demonstrates the neurotoxic properties of the excess of nitric oxide in the retina.

Protective effect of L-Arginine administration on proteins of unloaded m. soleus.

Cytoskeletal and contractile proteins degenerate during functional unloading of muscle. The ratio of myosin heavy chain (MHC) expression changes simultaneously. We have supposed that NO can be a signal molecule related to the regulation of protein metabolism upon muscle unloading. To test this hypothesis, Wistar rats underwent functional unloading for 14 days without and with peroral administration of L-arginine (500 mg/kg) as NO precursor. Significant decreases in m. soleus mass, NO, nNOS, dystrophin, Hsp90, p-S6K, and type I MHC mRNA contents were found in the group of animals with unloading without preparation compared to those in control and in the group with unloading and administration of L-arginine; at the same time, increased contents of atrogin-1/MAFbx and MuRF-1 (p < 0.05) were found. No difference in the IGF-1 mRNA content between all three groups was found. Atrophy was significantly less pronounced in the group with unloading and L-arginine administration compared to that without the amino acid, and no destruction of cytoskeletal proteins was observed. We conclude that administration of L-arginine upon functional unloading decreases the extent of m. soleus atrophy, prevents the decrease in it of type I MHC mRNA, and blocks destructive changes in some cytoskeletal proteins. Such effect can be due to the absence of increase in this group of the content of some ubiquitin ligases and decreased intensity of the p70S6 kinase synthesis marker.

[Nitrites can be reduced in retinal vessels during hypoxia and protect the retina against ischemia and apoptosis].

The possibility and the mechanism of the reduction of nitrites in retinal vessels under the acute hypoxia in vivo have been investigated. An experimental model of the rat retina ischemia was elaborated using the laser coagulation of retinal vessels. It was demonstrated that the vessel thrombosis does not occur if the nitrite concentration in the vessels is increased. It was proposed that, under acute hypoxia, nitrites are reduced to NO, which results in a drastic vasodilatation. Considering that the effect takes less than a minute, this reduction cannot be due to hypoxic acidosis but is more likely associated with NO reduction by heme proteins. It was found that the increased concentration of nitrites protects the retina from the development of ischemia progress and that the preliminary administration of nitrites prevents apoptosis in the retina and a decrease in its photoelectric activity.

[Molecular mechanisms of retinal ischemia].

The review discusses the molecular mechanisms of retinal damage, which are associated with retinal ischemia. Ischemia is one of the key factors determining the pathophysiology of many retinal diseases, such as diabetic retinopathy, glaucoma, anterior ischemic optic neuropathy, age-related macular degeneration, retinopathy of prematurity. Hypoxia and ischemia impair retinal neuronal energy metabolism, by launching a cascade of trigger reactions resulting in cell death. Oxidative stress, excitotoxicity, cell acidosis, inflammation, and others mechanisms acting in tandem are of considerable importance in ischemia. Neuronal apoptosis and neovascularization are the most important sequels of ischemia. Among all retinal neurons, ganglion cells are most susceptible to ischemia, which determines their early structural and functional changes in many ischemia-associated retinal diseases. The molecular mechanisms underlying the pathophysiology of ischemia-associated retinal diseases should be understood to substantiate and develop new therapy modalities.

[Protective effect of nitric oxide on cytoskeletal proteins in skeletal muscles under eccentric exercise].

The protective effect of nitric oxide (NO) on the cytoskeletal muscle proteins desmin and dystrophin has been studied under eccentric exercise. Experiments were performed on 28 male Wistar rats, which were divided into four groups: cage control (C, n = 7); group of eccentric exercise (running down a motor-driven treadmill, inclination 16 degrees) (20 m/min, 40 min running) (R, n = 7); eccentric exercise + L-arginine group (RA, n = 7) (with a daily supplementation of 500 mg/kg wt L-arginine for 3 days before the running); and eccentric exercise + L-NAME group (RN, n = 7) (with a daily supplementation of 90 mg/kg wt L-NAME (Nomega-nitro-L-arginine methyl ester, nNOS blocker) for 3 days before the running). It was found that increasing the NO concentration (in RA group) prevents the disruption of the dystrophin layer and decreases the loss of desmin in m. soleus under eccentric contraction, whereas in the R and RN groups the level of damage to dystrophin and desmin was significantly higher compared to the control rats. The inhibition of nNOS (by L-NAME) increases the nNOS mRNA level in the m. soleus, whereas increasing the NO concentration in m. soleus (L-arginine administration) does not affect the level of nNOS mRNA during the eccentric running. It was concluded that NO has a protective action on the cytoskeletal proteins desmin and dystrophin in skeletal muscle under eccentric contraction-induced damage.

[Antibodies to retinal S antigen in the tear and serum as an indicator of the nature of a course of endogenous uveitis in children].

Antibodies (IgM and IgG) to retinal S antigen were studied by enzyme immunoassay in the tear (n = 135) and blood serum (n = 221) samples taken from 45 children with chronic endogenous uveitis during a follow-up (for 6 months to 5 years). The studies have confirmed the early evidence that detection of serum autoantibodies may be used for the diagnosis of autoimmune and infectious-and-autoimmune uveitis, the verification and prediction of renal alterations, risks for lesions in the second eye in unilateral uveitis and prerecurrence in bilateral uveitis. Criteria for detecting antibodies to lacrimal S antigen were developed. Its has been ascertained that it is expedient to use this procedure as a method for controlling the efficiency of treatment in uveitis involving the posterior parts of the eye, confirming, and predicting the risk for involvement of the retina into an inflammatory process, detecting trends for development of chronic forms of both bilateral and unilateral uveitis. Simultaneous accumulation of IgM and/or IgG antibodies in the lacrimal fluid and serum, as well as imbalance, i.e. a prolonged enhancement of only local or only systemic response to S antigen (of both classes), are prognostically unfavorable.

A cyclic-AMP-gated conductance in cochlear hair cells.

The patch clamp technique was used to record cAMP-dependent currents of the guinea pig cochlear hair cell plasma membrane. Data obtained indicate that the channels passing this current are moderately selective for monovalent cations and are effectively blocked by L-cis-diltiazem and reversibly blocked by 1 mM Mg2+ or Ca2+. The single-channel unit conductance estimated in the absence of divalent cations is about 16 pS. The results demonstrate that cyclic nucleotide-dependent channels of cochlear hair cells are virtually identical to the photoreceptor and olfactory ones.

[Study of rhodopsin sulfhydryl groups in the photoreceptor membrane]. / Issledovanie sul'fgidril'nykh grupp rodopsina v fotoretseptornoi membrane.

The interaction between rhodopsin SH-groups in the photoreceptor membrane suspension with different titrating reagents (Ag HOGM, DTNB) was studied. After rhodopsin bleaching the number of free SH-groups increased from two in the dark to six after illumination. Such increase of SH-groups number was observed only by the amperometric titration procedure. The influence of the "dark" and "light exposed" SH-group modifications on regeneration ability of rhodopsin in the presence of 11-cis-retinal was investigated. No dependence of regeneration on SH-groups modification in the dark was observed, while modification of "light" SH-groups decreases rhodopsin regeneration ability. The distribution of SH-groups in rhodopsin molecules and SH-groups dependence on protein conformation are discussed.

[The absence of channel structures in the photoreceptor membrane of the rod disc]. / Ob otsutstvii kanal'nykh struktur v fotoretseptornoi membrane diska palochki.

Comparison of electric characteristics of photoreceptor disc and plasma membranes of photoreceptor was made by means of photopotential registration from the adhized to the impregnated by lipids filters photoreceptor discs or isolated rod outer segments. The resistance of the photoreceptor disc membrane is shown to be by three orders of magnitude higher than the resistance of photoreceptor plasma membrane; namely 1-2 MOhm X cm2 versus 1-2 KOhm X cm2. This is the evidence for the absence of channel structures in the disc membrane.

[Spectral sensitivity and visual pigments of the coastal crab Hemigrapsus sanguineus]. / Spektral'naia chuvstvitel'nost' i zritel'nye pigmenty pribrezhnogo kraba Hemigrapsus sanguineus.

It has been shown that the compound eye of the coastal crab has one photosensitive pigment rhodopsin and screening pigments, black and orange one. The orange pigment has lambda max = 480 nm, rhodopsin in digitonin is stable towards hydroxylamin action, has lambda max = 490-495 nm and after bleaching is transformed into free retinene and opsin. The pigments with lambda max = 430 and 475 nm of the receptor part of the eye are also solubilized. These pigments are not photosensitive but they dissociate under the effect of hydroxylamine. The curye of spectral sensitivity of the coastal crab has the basic maximum at approximately 525 nm and the additional one at 450 nm, which seems to be provided by a combination of the visual pigment--rhodopsin (lambda max 500 nm) with a carotinoid filter (lambda max 480-490). Specific features of the visual system of coastal crab are discussed.

[Manifestations of immunopathology and validation of immunotherapy of diabetic retinopathy]. / Proiavleniia immunopatologii i obosnovanie immunoterapii diabeticheskoi retinopatii.

Three-year clinical and immunological studies of 378 patients with diabetic retinopathy revealed involvement of the T- and B-immunity systems and the specific features of the local autoimmune response to the retinal S-antigen, which manifest during the early preclinical stage of diabetic retinopathy. The progress of retinopathy is associated with augmenting insufficiency of T-suppressors, inhibition of lymphocyte blastogenesis with phytohemagglutinin, and an increase in the levels of B-lymphocytes, IgM, and circulating immune complexes in the blood. Two abnormalities of autoimmune response of the eye to S-antigen were observed in patients with the proliferative forms: hypersensitivity and insufficiency of the immune response. A moderate level of S-antigen in tears is a protective factor, stabilizing retinopathy. The authors validate the significance of immunological test for predicting the course of retinopathy and emphasize the differentiated approach to local and total-system's correction of immune disorders in diabetics.

[Humoral immune response to the retinal S-antigen in premature infants and its role in the development and course of retinopathy of prematurity]. / Gumoral'nyi immunnyi otvet na S-antigen setchatki u nedonoshennykh detei i ego rol' v razvitii i techenii retinopatii nedonoshennykh.

The humoral immune response to the retinal S-antigen was studied in premature babies with active and cicatricle stages of retinopathy of the premature (RP) and in the controls (102 serum test). The presence of antibodies to the S-antigen of classes IgG and IgM was established by the enzyme multiplied analysis and by an authors' developed test-system. A definite specific humoral response to the S-antigen correlated with the nature of the course and prognosis of the disease was found in 71% of cases. The first peak of IgM-antibodies was found in babies of the risk-group (preretinopathy), it correlated with a poor prognosis (progression of RP). The second peak was highly pronounced in babies with the terminal cicatricle stages of RP. The wave-like dynamics of IgG-antibodies suggests that specific circulating immune complexes shape up. The role of immune responses, induced by the retinal S-antigen, in the RP pathogenesis is discussed.

[The clinico-immunological validation of a differentiated approach to the use of corticosteroids in treating S-dependent uveoretinitis]. / Kliniko-immunologicheskoe obosnovanie differentsirovannogo podkhoda k primeneniiu kortikosteroidov pri lechenii S-zavisimykh uveoretinitov.

A total of 630 patients with uveitis of different etiology aged 5 to 70 were examined. Signs of autoimmunization with retinal S-antigens (mol. weight 48 kD) associated with retinal involvement were detected in more than half of them. A moderate level of S-antigen in the tears was found to promote a favorable outcome of uveoretinitis. Deficit or a drastic increase of S-antigen titers in the tears, accumulation of S-antibodies and circulating S-antigen-antibody complexes in the serum, and blood leukocyte migration inhibition in response to S-antigen were observed in chronic and complicated cases. As many as 75% focal chorioretinitis and panuveitis cases, 50% of posterior and 37% of peripheral uveitis were referred to S-related forms. The authors validate a differentiated approach to the treatment of S-uveoretinitis. If S-antibodies are accumulated only in the tears, local corticosteroids are effective; if both local and total-systems reactions are boosted, the maximal effect may be achieved by local and systemic corticosteroids and cytostatics. In case of a deficiency of S-antibodies in the tears immunodepressive therapy was of no avail, and good results could be attained only by immunomodulating therapy: corticosteroids+hemoperfusion in adults and corticosteroids+thymus preparations and/or interferonogens in children.

[Tear fluid proteome variability in healthy donors].

The variability of control samples is the main problem in clinical proteomics and reliable sources for estimation of variability of normal content of different proteins are not numerous. Most of the investigations of normal human tear proteome include pool of samples as reference materials. But it is impossible to use such experimental approach to establish the range of variability of different tear proteome components. This study is the first attempt to estimate the variability of proteins content in healthy donors tear using high-performance liquid chromatography and tandem mass spectrometry. The protein profiles from 11 individual healthy donors were analyzed. Essential variability of the minor proteins was revealed while the presence of 6 major proteins in all 11 samples was invariable. We found the Lacritin glycosylation in all samples of tear fluid received from healthy donors. It seems that this modification is typical for healthy donors tear. The analysis of the pool samples was also carried out to estimate the availability for this approach for the search of ophthalmologic diseases biomarkers.