Multiple sensor optical thermometry system for application in clinical hyperthermia

Journal ArticleThe thermometry system described is based upon the temperature dependence of the band edge absorption of infrared light in GaAs crystal. The design of the thermometry was completed, and the system was subjected to an extensive evaluation, including testing with tissue phantoms and microwave applicators. The system has up to 12 temperature sensors which are packaged in two basic probe configurations: a single-sensor probe with a length of 1.2 m and a diameter of 0.6 mm; and a four-sensor linear array probe with a length of 1.2 m, diameter of 1.1 mm, and spacing of 1.5 cm between adjacent sensors. Results of thermometry evaluation are presented, including data on automatic calibration, temperature accuracy and stability, and EMI protection

Causes of bradycardia with static respiratory hypoxia in athletes

According to some literature data, during voluntary long-term breath holding (BH), the heart rate (HR) increases, and according to others, it decreases.Objective: to determine the psychophysiological parameters that cause a change in HR during BH in athletes with different resistance to respiratory hypoxia.Materials and methods: HR at BH was studied in 14 beginner athletes, 15 basketball players and 12 swimmers-divers. Duration of BH was recorded. The HR was recorded on a heart rate monitor. After recording an electrocardiogram, the standard deviation of the duration of cardiac cycles was calculated. The arterial oxygen saturation was measured with a pulse oximeter. The statistically significant values of the correlation coefficient (r) were ≥0.33 with p < 0.05.Results: it was found that out of 41 sportsmen, HR increased by more than 5 % in 4, changed insignificantly in 7 and decreased by less than 5 % in 30. Beginner athletes had tachycardia, and BH was quickly interrupted by an imperative inhalation. The saturation of arterial blood with oxygen did not change and did not affect the change in HR. The decrease in heart rate in swimmers-divers in comparison with the other two groups of people examined was statistically significant (p < 0.05). The duration of BH had a direct correlation (r = 0.5) with bradycardia in these people. The duration of BH caused (r = 0.8) hypoxia, the value of which also directly influenced (r = 0.38) the severity of bradycardia. In addition, the decrease in HR depended on high HR (r = 0.36) and low HR variability (r = 0.38) before BH.Conclusion: tachycardia occurs in beginner athletes who experience discomfort with BH. Bradycardia occurs in sportsmen with a long-term BH setting without discomfort. Sympathicotonia in the prelaunch state predetermines the severity of bradycardia in BH. The duration of BH and the resulting hypoxia provide the occurrence of bradycardia

Psychophysiological processes, ensuring the achievement of sports results

Objective: to investigate the role of psychophysiological processes in achieving sports results.Materials and methods: the driving force of sports behavior was measured in free­divers, basketball players and athletes, which consisted of motivation to achieve sports results, emotional stress, situational information, hypoxic stability, and physical endurance. Then the sportsmen rotated the pedals of the bicycle ergometer with simultaneous intermittent breath holdings from 20 to 60 s.Results: it has been established that all components of the driving force of behavior are necessary for the sports activity of all groups of sportsmen. For the driving force of free­divers’ behavior, hypoxic stability is of greatest importance (r = 0.59), for basketball players — emotional stress (r = 0.6) and for athletes — emotional stress and situational information (r = 0.71 and 0.58). In addition, hypoxic stability and physical endurance directly affect the final sports result (r = 0.7 and 0.65) in conjunction with the driving force of behavior (r = 0.53).Conclusion: sports result is provided by the driving force behind the behavior of sportsmen. For free­divers, hypoxic stability is of primary importance, for basketball players — physical endurance and emotional stress, and for athletes — the totality of all components of the driving force of behavior

The structure of the ternary Eg5–ADP–ispinesib complex

The human kinesin Eg5 is responsible for bipolar spindle formation during early mitosis. Inhibition of Eg5 triggers the formation of monoastral spindles, leading to mitotic arrest that eventually causes apoptosis. There is increasing evidence that Eg5 constitutes a potential drug target for the development of cancer chemotherapeutics. The most advanced Eg5-targeting agent is ispinesib, which exhibits potent antitumour activity and is currently in multiple phase II clinical trials. In this study, the crystal structure of the Eg5 motor domain in complex with ispinesib, supported by kinetic and thermodynamic binding data, is reported. Ispinesib occupies the same induced-fit pocket in Eg5 as other allosteric inhibitors, making extensive hydrophobic interactions with the protein. The data for the Eg5-ADP-ispinesib complex suffered from pseudo-merohedral twinning and revealed translational noncrystallographic symmetry, leading to challenges in data processing, space-group assignment and structure solution as well as in refinement. These complications may explain the lack of available structural information for this important agent and its analogues. The present structure represents the best interpretation of these data based on extensive data-reduction, structure-solution and refinement trials

Heart rate variability during speed-strength load of athletes after hypoventilation training

Objective: to study the variability of the heart rate of athletes during hypoventilation training, which provides an increase in the result of speed-strength load.Materials and methods: Athletes performed speed-strength load with their hands on a training apparatus against the background of maximum voluntary breath holding before and after hypoventilation training. The duration of breath holding, the number of power movements, parameters of heart rate variability and electromyography were measured.Results: After hypoventilation training of athletes at rest, parasympathetic influences on the heart rate increased, which led to an increase in the total power of the heart rate spectrum from 3201 ± 520 to 4047 ± 585 ms2, the power of the low frequency of the heart rate spectrum from 1458 ± 216 to 2055 ± 392 ms2 and the standard deviation of the duration of adjacent cardiac cycles from 45 ± 5 to 52 ± 4 ms. Sympathetic influences increased during exercise against the background of maximum voluntary breath holding. The longer maximum voluntary breath holding was, the more power movements the athletes performed.Conclusion: Hypoventilation training changed the vagosympathetic balance of the athletes’ body, increasing their performance and hypoxic resistance

Molecular basis for passive immunotherapy of Alzheimer's disease

Amyloid aggregates of the amyloid-{beta} (A{beta}) peptide are implicated in the pathology of Alzheimer's disease. Anti-A{beta} monoclonal antibodies (mAbs) have been shown to reduce amyloid plaques in vitro and in animal studies. Consequently, passive immunization is being considered for treating Alzheimer's, and anti-A{beta} mAbs are now in phase II trials. We report the isolation of two mAbs (PFA1 and PFA2) that recognize A{beta} monomers, protofibrils, and fibrils and the structures of their antigen binding fragments (Fabs) in complex with the A{beta}(1–8) peptide DAEFRHDS. The immunodominant EFRHD sequence forms salt bridges, hydrogen bonds, and hydrophobic contacts, including interactions with a striking WWDDD motif of the antigen binding fragments. We also show that a similar sequence (AKFRHD) derived from the human protein GRIP1 is able to cross-react with both PFA1 and PFA2 and, when cocrystallized with PFA1, binds in an identical conformation to A{beta}(1–8). Because such cross-reactivity has implications for potential side effects of immunotherapy, our structures provide a template for designing derivative mAbs that target A{beta} with improved specificity and higher affinity

Purification, crystallization and characterization of the Pseudomonas outer membrane protein FapF, a functional amyloid transporter

Bacteria often produce extracellular amyloid fibres via a multi-component secretion system. Aggregation-prone, unstructured subunits cross the periplasm and are secreted through the outer membrane, after which they self-assemble. Here, significant progress is presented towards solving the high-resolution crystal structure of the novel amyloid transporter FapF from Pseudomonas, which facilitates the secretion of the amyloid-forming polypeptide FapC across the bacterial outer membrane. This represents the first step towards obtaining structural insight into the products of the Pseudomonas fap operon. Initial attempts at crystallizing full-length and N-terminally truncated constructs by refolding techniques were not successful; however, after preparing FapF106-430 from the membrane fraction, reproducible crystals were obtained using the sitting-drop method of vapour diffusion. Diffraction data have been processed to 2.5 Å resolution. These crystals belonged to the monoclinic space group C121, with unit-cell parameters a = 143.4, b = 124.6, c = 80.4 Å, [alpha] = [gamma] = 90, [beta] = 96.32° and three monomers in the asymmetric unit. It was found that the switch to complete detergent exchange into C8E4 was crucial for forming well diffracting crystals, and it is suggested that this combined with limited proteolysis is a potentially useful protocol for membrane [beta]-barrel protein crystallography. The three-dimensional structure of FapF will provide invaluable information on the mechanistic differences of biogenesis between the curli and Fap functional amyloid systems

Structural and catalytic effects of surface loop-helix transplantation within haloalkane dehalogenase family

Engineering enzyme catalytic properties is important for basic research as well as for biotechnological applications. We have previously shown that the reshaping of enzyme access tunnels via the deletion of a short surface loop element may yield a haloalkane dehalogenase variant with markedly modified substrate specificity and enantioselectivity. Here, we conversely probed the effects of surface loop-helix transplantation from one enzyme to another within the enzyme family of haloalkane dehalogenases. Precisely, we transplanted a nine-residue long extension of L9 loop and alpha 4 helix from DbjA into the corresponding site of DbeA. Biophysical characterization showed that this fragment transplantation did not affect the overall protein fold or oligomeric state, but lowered protein stability (Delta T-m = -5 to 6 degrees C). Interestingly, the crystal structure of DbeA mutant revealed the unique structural features of enzyme access tunnels, which are known determinants of catalytic properties for this enzyme family. Biochemical data confirmed that insertion increased activity of DbeA with various halogenated substrates and altered its enantioselectivity with several linear beta-bromoalkanes. Our findings support a protein engineering strategy employing surface loop-helix transplantation for construction of novel protein catalysts with modified catalytic properties

Vanadium containing bromoperoxidase--insights into the enzymatic mechanism using X-ray crystallography.

addresses: School of Biosciences, University of Exeter, Exeter, UK. [email protected]: Journal Article; Research Support, Non-U.S. Gov'tCopyright © 2009 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Inorganic Biochemistry. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Inorganic Biochemistry, 2009, Vol. 103, Issue 4, pp. 617 – 621 DOI: 10.1016/j.jinorgbio.2009.01.011The X-ray crystal structure of the vanadium bromoperoxidase from the red algae Corallina pilulifera has been solved in the presence of the known substrates, phenol red and phloroglucinol. A putative substrate binding site has been observed in the active site channel of the enzyme. In addition bromide has been soaked into the crystals and it has been shown to bind unambiguously within the enzyme active site by using the technique of single anomalous dispersion. A specific leucine amino acid is seen to move towards the bromide ion in the wild-type enzyme to produce a hydrophobic environment within the active site. A mutant of the enzyme where arginine 397 has been changed to tryptophan, shows a different behaviour on bromide binding. These results have increased our understanding of the mechanism of the vanadium bromoperoxidases and have demonstrated that the substrate and bromide are specifically bound to the enzyme active site