Role of agr (RNAIII) in Staphylococcus aureus adherence to fibrinogen, fibronectin, platelets and endothelial cells under static and flow conditions.

In the present study, the adherence of Staphylococcus aureus (strain 83254) and its RNAIII mutant (WA400) to immobilised fibrinogen and fibronectin, and to human endothelial cells (EC), was studied. [3H]Thymidine-labelled bacteria in stationary phase were incubated on the test surfaces for 20 min under static or flow (200/s) conditions. The results showed: (a) increased adherence of the RNAIII mutant to fibrinogen under static conditions, and decreased adherence of the mutant to fibronectin and EC under both static and flow conditions compared with the parental strain; (b) stronger ability of the mutant compared with the parental strain to induce platelet aggregation in suspension; (c) greater adherence of the parental strain and the mutant to EC pre-treated with platelet-rich plasma compared with platelet-poor plasma, and to EC pre-treated with platelet-poor plasma compared with control; (d) increased adherence of S.

Venous shear stress enhances platelet mediated staphylococcal adhesion to artificial and damaged biological surfaces.

We investigated the role of blood components in the adhesion of staphylococci to biological and artificial surfaces under well-defined flow conditions by using the Cone and Plate(let) Analyzer. An enzyme-linked immunosorbent assay-like binding assay with biotinylated bacteria determined the extent of bacterial adhesion to subendothelial extracellular matrix (ECM), polystyrene (PS) and adult bovine aortic endothelial (ABAE) cell monolayer. The presence of adsorbed plasma proteins on PS and ECM did not increase and in some cases reduced staphylococcal adhesion under flow conditions (200s(-1)).

[Structural-metabolic plasticity of mammalian skeletal muscles in hypokinesis and weightlessness].

Under review are investigations of the contractile structure of skeletal muscles of humans and animals (rats and primates) following space flight, long-term hypokinesia, immersion (human subjects) and head-down suspension (rats). Close consideration is given to experimental testing of hypotheses concerning neuronal, humoral and cell processes leading to atrophy. Described are consistencies and mechanisms of changes in the myosin phenotype and electromechanic coupling in muscular fibers as well as their capillarization and energy potential.

Effect of support stimulation on unloaded soleus in rat.

We studied the efficacy of plantar support in the prevention of atrophy in a disused soleus muscle during hindlimb suspension (HS). The 14-day investigation involved three groups of hindlimb-suspended male Wistar rats and a group of control rats (C). In all HS groups, the left hindlimbs (L) of the animals were left free.

[Changes in structure and metabolism in the m. vastus lateralis in monkeys after a space flight].

Monkeys developed a significant reduction in size of the m. vastus lateralis' fast and slow fibres, the amount of protein in them remaining the same.

Factor XIII mediates adhesion of platelets to endothelial cells through alpha(v)beta(3) and glycoprotein IIb/IIIa integrins.

Coagulation factor XIII (FXIII) is a transglutaminase that catalyzes crosslink formation in fibrin clots. Endothelial cells (EC) were demonstrated to bind FXIII via their alpha(v)beta3 integrin receptor. FXIII was also shown to bind platelet glycoprotein IIb/IIIa receptor.

[Effect of weightlessness and movement restraint on structure and metabolism of M. soleus in monkeys after space flight].

After staying in real and simulated weightlessness, the most obvious changes were recorded in the "slow" tonic muscles like m. soleus, the protein loss in the fibres being greater than the loss of other components, water included.

Whole blood platelet deposition on extracellular matrix under flow conditions in preterm neonatal sepsis.

Unlabelled: Platelet function in preterm infants with sepsis was evaluated by measuring their adhesion and aggregation properties using the Cone and Plate(let) Analyser. This may lead to earlier detection of bleeding tendency in septic infants. Platelet function was investigated in 54 preterm infants, of whom 32 had proven neonatal sepsis and 22 were healthy matched controls.

Deposition of whole blood platelets on extracellular matrix under flow conditions in preterm infants.

Background: A previous study showed greater adhesion by platelets of healthy full term infants to subendothelial extracellular matrix (ECM) under flow conditions compared with healthy adult platelets.

Aim: To investigate the adhesion and aggregation of platelets from preterm infants on ECM under defined shear conditions.

Methods: In vitro platelet function was investigated in 106 preterm infants, 74 full term infants, and 26 healthy adults.

[Structural and metabolic characteristics of m. vastus lateralis of monkeys during 30-day hypokinesia: effects of prophylactic Gz-accelerations].

Studies of m. vastus lateralis in Rhesus monkeys exposed to weightlessness on board of the Russian biosatellites showed the profound changes of the muscle structural and metabolic profile. It is known that exposure to head-down tilt berets (BR) induces the similar changes though not so pronounced.

Ultrastructure of skeletal muscles of rhesus monkeys after spaceflight.

The ultrastructure of myofibrillar and mitochondrial apparatus of m. soleus and m. vastus lateralis of Bion 11 monkeys was investigated.

Structural and metabolic profile of rhesus monkey m. vastus lateralis after spaceflight.

The effect of microgravity on slow- and fast-twitch fibers of m. vastus lateralis of rhesus monkeys was investigated. After real flight, fibers of both types were reduced in size, whereas after simulated flight, only type I fibers tended to diminish.

Effect of spaceflight on single fiber function of triceps and biceps muscles in rhesus monkeys.

Primates appeared to be a good model for investigating muscle contractile and biochemical properties, as well as EMG recordings. The purpose of our study was to examine the effects of microgravity on the contractile properties of the slow-type triceps and fast-type biceps muscles during the 14-day Bion 11 spaceflight.

Structural changes in arm muscles after microgravity.

Disuse muscle atrophy is a well-known consequence of spaceflight. However, most of the available muscle data concern lower limb muscles of rats and primates exposed to microgravity aboard Russian Cosmos biosatellites and American Space Shuttles. The purpose of our study was, therefore, to provide information concerning the effects of a 14-day spaceflight on two upper limb muscles of rhesus monkeys (Macaca mulatta).

Structural and metabolic characteristics of rhesus monkey m. soleus after spaceflight.

The effect of microgravity and diminished motor activity on m. soleus fibers of rhesus monkeys was investigated. A significant size reduction of both slow- and fast-twitch fibers was found in the flight animals only.

Influence of single hindlimb support on fiber characteristics of unloaded skeletal muscle.

The unweighting and/or immobilization in the shortened position leads to muscle atrophy, slow-to-fast transformation and biochemical alterations in muscle fibers. This process could be prevented by the stretching or loaded contraction. On the other hand Kozlovskaya et al.

What is the trigger mechanism for changes of the oxidative potential in skeletal muscle?

It is known that the long-duration decline of high-energy phosphates(HP) level in skeletal muscles, induced by administration of beta-guanidinpropionic acid (beta-GPA), is followed by the increase of mitochondrial enzyme activities (MEA). The same increase of MEA was observed in the course of physical exercise training. The decrease of MEA and at the same time the increase of HP levels were found under gravitational unloading.

Time-course of human muscle fibre size reduction during head-down tilt bedrest.

The first studies of space flown rats revealed that in m.soleus (SOL) slow-twitch fibers (ST) were reduced in size more pronouncedly than fast-twitch fibers (FT). The same differences in the fiber atrophy levels were found in rats after hind-limb suspension.

Effects of three days of dry immersion on heart rate and blood pressure variabilities during head-up tilting in humans.

In this study we examined the effects of 3 days of dry immersion on heart rate variability (HRV) and blood pressure variability (BPV) in response to head-up tilting in 4 healthy young subjects aged 21 to 36 years. Resting value of the high-frequency (HF) power of BPV and HRV decreased, while the low-frequency (LF)/HF ratio of HRV and blood pressure increased after the dry immersion. The HF power of HRV decreased, while the LF/HF ratio of HRV and heart rate increased during head-up tilting before and after dry immersion.

Adherence properties of Staphylococcus aureus under static and flow conditions: roles of agr and sar loci, platelets, and plasma ligands.

Global regulatory genes in Staphylococcus aureus, including agr and sar, are known to regulate the expression of multiple virulence factors, including cell wall adhesins. In the present study, the adherence of S. aureus RN6390 (wild type), RN6911 (agr), ALC136 (sar), and ALC135 (agr sar) to immobilized fibrinogen, fibronectin, von Willebrand factor (vWF), extracellular matrix (ECM), and human endothelial cells (EC) EAhy.

Transient adhesion refractoriness of circulating platelets under shear stress: the role of partial activation and microaggregate formation by suboptimal ADP concentration.

Exposure of whole blood (WB) to subendothelial extracellular matrix (ECM) under shear stress in the cone and plate(let) analyser (CPA) results in platelet adhesion, followed by release reaction and aggregation of circulating platelets on the adherent platelets. The properties of circulating non-adhered platelets in the CPA was studied by exposure of WB to ECM at a high shear rate (1300/s) for 2 min (1st run), followed by transfer of the suspension to a new ECM-coated well for a second run (2nd run) under similar conditions. The results of the 2nd run demonstrated transient adhesion refractoriness associated with platelet microaggregate formation in the suspension.

[Dynamics of human muscle fibers atrophy during long-term head-down hypokinesia].

The dynamics of atrophy in the muscles-extensors of the leg and thigh during long-term hypokinesia was studied with the model of head-down tilt (HDT -6 degrees) in a series of two experiments (120 and 60 days in duration) with participation of men and women. Dynamics of the cross-sectional area of human muscular fibers was characterized by similar atrophy of the fast and slow fibers on the first stage of HDT. Later on, the size of fast fibers in m.

S-nitrosoderivative of a recombinant fragment of von Willebrand factor (S-nitroso-AR545C) inhibits thrombus formation in guinea pig carotid artery thrombosis model.

Antiplatelet drugs are the mainstays of therapy for acute and chronic cardiovascular diseases. S-nitroso-AR545C - an S-nitrosoderivative of a recombinant von Willebrand factor fragment AR545C spanning Ala 444 to Asp 730 and containing an Arg 545 Cys mutation, was previously found to inhibit ristocetin- and ADP-induced platelet aggregation and the interaction of platelets with extracellular matrix (ECM). In the current study we tested the antithrombotic properties of S-nitroso-AR545C on guinea pig platelets and in a platelet-rich thrombosis model in the guinea pig.