Breathing pattern and its evaluation by muscle dynamometer md03.

The purpose of the study was to determine the proportion of engagements of individual breathing sectors during 1-min physically active breathing at rest in 163 healthy, physically active participants (students of Physical Education and Sport). The research analyzed breathing movements through the muscle dynamometer MD03 (Hitron, Plzen, Czech Republic). The proportion of engagements of the individual breathing sector in the group analyzed was determined based on measurement results. The lower breathing sector was engaged at 29.2%, the middle breathing sector at 31.0%, and the upper breathing sector at 39.8%. The largest observed difference between the involvement of individual breath sectors was 10.6% between the lower and upper breathing sectors. The muscle dynamometer MD03 may be instrumental for practising both localized breathing and full breath.

Fast and reliable pre-approach for scanning probe microscopes based on tip-sample capacitance.

Within the last three decades Scanning Probe Microscopy has been developed to a powerful tool for measuring surfaces and their properties on an atomic scale such that users can be found nowadays not only in academia but also in industry. This development is still pushed further by researchers, who continuously exploit new possibilities of this technique, as well as companies that focus mainly on the usability. However, although imaging has become significantly easier, the time required for a safe approach (without unwanted tip-sample contact) can be very time consuming, especially if the microscope is not equipped or suited for the observation of the tip-sample distance with an additional optical microscope. Here we show that the measurement of the absolute tip-sample capacitance provides an ideal solution for a fast and reliable pre-approach. The absolute tip-sample capacitance shows a generic behavior as a function of the distance, even though we measured it on several completely different setups. Insight into this behavior is gained via an analytical and computational analysis, from which two additional advantages arise: the capacitance measurement can be applied for observing, analyzing, and fine-tuning of the approach motor, as well as for the determination of the (effective) tip radius. The latter provides important information about the sharpness of the measured tip and can be used not only to characterize new (freshly etched) tips but also for the determination of the degradation after a tip-sample contact/crash.

Subsurface contrast due to friction in heterodyne force microscopy.

The nondestructive imaging of subsurface structures on the nanometer scale has been a long-standing desire in both science and industry. A few impressive images were published so far that demonstrate the general feasibility by combining ultrasound with an atomic force microscope. From different excitation schemes, heterodyne force microscopy seems to be the most promising candidate delivering the highest contrast and resolution. However, the physical contrast mechanism is unknown, thereby preventing any quantitative analysis of samples. Here we show that friction at material boundaries within the sample is responsible for the contrast formation. This result is obtained by performing a full quantitative analysis, in which we compare our experimentally observed contrasts with simulations and calculations. Surprisingly, we can rule out all other generally believed responsible mechanisms, like Rayleigh scattering, sample (visco)elasticity, damping of the ultrasonic tip motion, and ultrasound attenuation. Our analytical description paves the way for quantitative subsurface-AFM imaging.

Resonance frequencies of AFM cantilevers in contact with a surface.

To make the forces in an Atomic Force Microscope that operates in a dynamic mode with one or multiple vibrations applied to the cantilever, quantitative, one needs to relate a change in resonance frequency of the cantilever to a specific tip-sample interaction. Due to the time dependence of the force between the tip and sample caused by the vibrations, this task is not only difficult, but in fact only possible to solve for certain limiting cases, if one follows common theoretical approaches with a Taylor expansion around the deflection point. Here, we present an analytical method for calculating the resonance frequencies of the cantilever that is valid for any tip-sample interaction. Instead of linearizing the tip-sample interaction locally, we calculate an averaged, weighted linearization taking into account all positions of the tip while vibrating. Our method bridges, therefore, the difficult gap between a free oscillating cantilever and a cantilever that is pushed infinitely hard into contact with a surface, which describes a clamped-pinned boundary condition. For a correct description of the cantilever dynamics, we take into account both the tip mass and the tip moment of inertia. Applying our model, we show that it is possible to calculate the modal response of a cantilever as a function of the tip-sample interaction strength. Based on these modal vibration characteristics, we show that the higher resonance frequencies of a cantilever are completely insensitive to the strength of the tip-sample interaction.

Quantitative methods for studying hemostasis in zebrafish larvae.

Hemostasis is a coordinated system through which blood is prevented from exiting a closed circulatory system. We have taken advantage of the zebrafish, an emerging model for the study of blood coagulation, and describe three techniques for quantitative analysis of primary and secondary hemostasis. Collectively, these three techniques comprise a toolset to aid in our understanding of hemostasis and pathological clotting.

A subsurface add-on for standard atomic force microscopes.

The application of ultrasound in an Atomic Force Microscope (AFM) gives access to subsurface information. However, no commercially AFM exists that is equipped with this technique. The main problems are the electronic crosstalk in the AFM setup and the insufficiently strong excitation of the cantilever at ultrasonic (MHz) frequencies. In this paper, we describe the development of an add-on that provides a solution to these problems by using a special piezo element with a lowest resonance frequency of 2.5 MHz and by separating the electronic connection for this high frequency piezo element from all other connections. In this sense, we support researches with the possibility to perform subsurface measurements with their existing AFMs and hopefully pave also the way for the development of a commercial AFM that is capable of imaging subsurface features with nanometer resolution.

Beating beats mixing in heterodyne detection schemes.

Heterodyne detection schemes are widely used to detect and analyse high-frequency signals, which are unmeasurable with conventional techniques. It is the general conception that the heterodyne signal is generated only by mixing and that beating can be fully neglected, as it is a linear effect that, therefore, cannot produce a heterodyne signal. Deriving a general analytical theory, we show, in contrast, that both beating and mixing are crucial to explain the heterodyne signal generation. Beating even dominates the heterodyne signal, if the nonlinearity of the mixing element (mixer) is of higher order than quadratic. The specific characteristic of the mixer determines its sensitivity for beating. We confirm our results with both a full numerical simulation and an experiment using heterodyne force microscopy, which represents a model system with a highly non-quadratic mixer. As quadratic mixers are the exception, many results of previously reported heterodyne measurements may need to be reconsidered.

Neutron skin of (208)pb from coherent pion photoproduction.

Information on the size and shape of the neutron skin on (208)Pb is extracted from coherent pion photoproduction cross sections measured using the Crystal Ball detector together with the Glasgow tagger at the MAMI electron beam facility. On exploitation of an interpolated fit of a theoretical model to the measured cross sections, the half-height radius and diffuseness of the neutron distribution are found to be c(n)=6.70±0.03(stat.) fm and a(n)=0.55±0.01(stat.)(-0.03)(+0.02)(sys.) fm, respectively, corresponding to a neutron skin thickness Δr(np)=0.15±0.03(stat.)(-0.03)(+0.01)(sys.) fm. The results give the first successful extraction of a neutron skin thickness with an electromagnetic probe and indicate that the skin of (208)Pb has a halo character. The measurement provides valuable new constraints on both the structure of nuclei and the equation of state for neutron-rich matter.

Improving the accuracy of walking piezo motors.

Many application areas require ultraprecise, stiff, and compact actuator systems with a high positioning resolution in combination with a large range as well as a high holding and pushing force. One promising solution to meet these conflicting requirements is a walking piezo motor that works with two pairs of piezo elements such that the movement is taken over by one pair, once the other pair reaches its maximum travel distance. A resolution in the pm-range can be achieved, if operating the motor within the travel range of one piezo pair. However, applying the typical walking drive signals, we measure jumps in the displacement up to 2.4 µm, when the movement is given over from one piezo pair to the other. We analyze the reason for these large jumps and propose improved drive signals. The implementation of our new drive signals reduces the jumps to less than 42 nm and makes the motor ideally suitable to operate as a coarse approach motor in an ultra-high vacuum scanning tunneling microscope. The rigidity of the motor is reflected in its high pushing force of 6.4 N.

Cantilever dynamics in Heterodyne Force Microscopy.

Experiments in Heterodyne Force Microscopy (HFM) show the possibility to image deeply buried nanoparticles below a surface. However, the contrast mechanism and the motion of the cantilever, which detects the subsurface signal, are not yet understood. We present a numerical study of the cantilever motion in different HFM modes using realistic tip-sample interactions. The results provide information on the sensitivity to the heterodyne signal. The parameters in our calculations are chosen as closely as possible to the situation in real experiments to enable (future) comparisons based on our predictions. In HFM both the tip and the sample are excited at slightly different ultrasonic frequencies such that a difference frequency is generated that can contain subsurface information. We calculate the amplitude and phase of the difference frequency generated by the motion of the cantilever. The amplitude shows a local maximum in the attractive Van-der-Waals regime and an even higher plateau in the repulsive regime. The phase shifts 180° or 90°, depending on the mode of operation. Finally, we observe oscillations in both the amplitude and the phase of the difference frequency, which are caused by a shift of the resonance frequency of the cantilever and an involved transient behavior.

Subsurface-AFM: sensitivity to the heterodyne signal.

Applying heterodyne force microscopy (HFM), it has been impressively demonstrated that it is possible to obtain subsurface information: 20 nm large gold nanoparticles that were buried 500 nm deep have been imaged. It is the heterodyne signal that contains the subsurface information. We elucidate, both theoretically and experimentally, the sensitivity to the heterodyne signal as a function of the tip-sample distance. This is crucial information for experiments as the distance, and therefore the sensitivity, is tunable. We show that the amplitude of the heterodyne signal has a local maximum in the attractive part of the tip-sample interaction, before it surprisingly reaches an even higher plateau, when the tip-sample interaction is repulsive. This can only be explained by a non-decreasing amplitude of the ultrasonic motion of the tip, although it is in full contact with the surface. We confirm this counterintuitive tip behavior experimentally even on a hard surface like silicon.

Veno-venous extracorporeal membrane oxygenation (ECMO) support during anaesthesia for oesophagectomy.

The use of extracorporeal membrane oxygenation in adults has increased in popularity and importance for the support of patients with cardiac or pulmonary failure. Although it is now quite commonly used in the intensive care unit, its use has rarely been described as a means of support during anaesthesia and surgery. We report the case of a patient who required curative resection of the oesophagus following previous left pneumonectomy where veno-venous extracorporeal membrane oxygenation was required both during surgery and for the first three days postoperatively. We describe the anaesthetic management of this patient who only had a single lung, review other alternatives and discuss why extracorporeal membrane oxygenation was particularly suited to this case. To the best of our knowledge, the anaesthetic literature to date does not contain a case report of this type.

Design of a high-speed electrochemical scanning tunneling microscope.

In this paper, we present a bottom-up approach to designing and constructing a high-speed electrochemical scanning tunneling microscope (EC-STM). Using finite element analysis (FEA) calculations of the frequency response of the whole mechanical loop of the STM, we analyzed several geometries to find the most stable one that could facilitate fast scanning. To test the FEA results, we conducted measurements of the vibration amplitudes using a prototype STM setup. Based on the FEA analysis and the measurement results, we identified the potentially most disturbing vibration modes that could impair fast scanning. By modifying the design of some parts of the EC-STM, we reduced the amplitudes as well as increased the resonance frequencies of these modes. Additionally, we designed and constructed an electrochemical flow-cell that allows STM imaging in a flowing electrolyte, and built a bi-potentiostat to achieve electrochemical potential control during the measurements. Finally, we present STM images acquired during high-speed imaging in air as well as in an electrochemical environment using our newly-developed EC-STM.

[Relationship of acromial morphology and rotator cuff tears]. / Vztah tvaru akromia a ruptury rotátorové manzety.

PURPOSE OF THE STUDY: To evaluate the effect of acromial morphology, as assessed on radiographs, on rotator cuff tears. MATERIAL: A total of 200 patients surgically treated for shoulder disorders were enrolled. All were older than 40 years and had good quality shoulder radiographs. Two groups were composed: First, a clinical model group of 136 patients to be investigated for three parameters of rotator cuff injury that was divided into two subgroups. One included 68 patients, with an average age of 53.5 years, in whom surgery revealed no injury to the rotator cuff; the other subgroup of 68 patients, with an average age of 58 years, had a ruptured supraspinatus tendon. Subsequently, a control group of 64 patients (32 with rotator cuff injury and 32 without it) was used to verify the results of the model group. METHODS: Three parameters describing the acromion, i.e., acromion index (AI), lateral acromion angle and acromial slope, were measured on standard radiographs. Tangential antero-posterior and scapular "Y" (supraspinatus outlet) views were taken, the images were digitalised and evaluated using a TomoCon 3.0 Viewer programme, and the results of the two groups were statistically analysed and compared. RESULTS: The difference between the patients with rotator cuff injury and those without it was best shown, in both groups, by significant differences in the acromion index. This was true for both the men and women. The AI values for the patients with rotator cuff injury were 0.66 and 0.65 in the model and control groups, respectively. The same AI value of 0.76 was found for uninjured rotator cuffs in both groups. The two other parameters investigated did not appear to be of any significant validity for assessment of rotator cuff tears. DISCUSSION: The aetiology of injury to the rotator cuff has not been fully understood yet but, undoubtedly, the causes will be many. The shape of the acromion is regarded as one of the important factors. We agree with Nyffeler et al. that a lateral extension of the acromion is most often associated with rotator cuff tears and that the acromion index proposed by these authors is a good parameter to assess this morphological change. CONCLUSIONS: A lateral extension of the acromion plays an important role in the aetiology of degenerative tears of the supraspinatus tendon. The acromion index appears to be the best instrument for assessing this morphological change.

Subsurface atomic force microscopy: towards a quantitative understanding.

Recent experiments in the field of subsurface atomic force microscopy have demonstrated that it is possible to nondestructively image micro- and even nanoparticles that are embedded significantly deep within the bulk of a sample. In order to get insights into the contrast formation mechanism, we performed a finite element analysis and an analytical study, in which we calculated the amplitude and phase variation on the surface of an ultrasound wave that has traveled through the sample. Our calculations were performed as closely as possible to the situation in the experiments to enable a (future) comparison based on our predictions. We show that Rayleigh scattering of acoustic waves accounts for the measured contrast and we verify the characteristic Rayleigh dependences. The numerical results show that the contrast is independent of the depth at which a particle is buried, whereas the analytical study reveals a 1/depth dependence. In addition, we find a large deviation in the width of the particle in the contrast at the surface when applying the numerical or the analytical calculation respectively. These results indicate the importance of both the reflections of sound waves at the sample interfaces and bulk damping, as both are treated differently in our two models.

Activated CD8+ T cells contribute to clearance of gastric Cryptosporidium muris infections.

The role of CD4+ and CD8+ T lymphocytes in the development of a protective immune response against Cryptosporidium muris infection was studied by the reconstitution of severe combined immunodeficient (SCID) mice with well-defined populations of either naive or immune CD8+ or CD4+ T lymphocytes. Adoptive transfer of both naive and immune CD4+ T lymphocyte subpopulations protects SCID mice against cryptosporidiosis. Moreover, a significant biological impact of activated CD8+ T cells against gastric cryptosporidiosis was observed. The significant difference in the course and intensity of the infection in reconstituted SCID mice was found to be dependent on the protective function of both the CD4+ and CD8+ T-cell populations transferred. While SCID mice reconstituted with either immune or naive CD4+ or immune CD8+ T-cell subpopulations resolved the infection within 29, 37 and 51 days post-infection, respectively, those reconstituted with naive CD8+ T cells suffered from chronic infection similar to control SCID mice. Reconstitution with CD4+ T cells resulted in suppression of oocyst excretion and shortening of patent period in comparison with SCID mice reconstituted with CD8+ T cells. Thus, although CD4+ T cells are considered important in protective immunity, our results are the first to demonstrate the involvement of activated CD8+ T lymphocytes in the protection of mice against gastric cryptosporidiosis.

Molecular characterization of Cryptosporidium spp. in pre-weaned dairy calves in the Czech Republic: absence of C. ryanae and management-associated distribution of C. andersoni, C. bovis and C. parvum subtypes.

A total of 750 faecal samples of dairy calves at up to 2 months of age kept in various housing systems were screened for Cryptosporidium spp. infection using the aniline-carbol-methyl violet staining method. DNA was extracted from Cryptosporidium positive samples and from 150 randomly selected microscopically negative samples. Nested PCR was performed to amplify the partial SSU rRNA gene of Cryptosporidium that was subsequently digested by SspI, VspI and MboII restriction enzymes to determine the present Cryptosporidium species and genotype. In addition, the samples characterized as Cryptosporidium parvum were subsequently analyzed at the GP60 gene to determine the distribution of zoonotic subtypes. Sequence analyses and RFLP identified C. parvum in 137, Cryptosporidium andersoni in 21 and Cryptosporidium bovis in 3 samples. Neither mixed infections nor Cryptosporidium ryanae was detected. Sequencing of the GP60 gene from C. parvum-positive samples revealed all five subtypes of family IIa (A15G2R1, A16G1R1, A22G1R1, A18G1R1, and A15G1R1). The obvious management-associated distribution of Cryptosporidium spp. was demonstrated. Direct contact with adult animals was found to be a risky factor for C. andersoni and C. bovis infection. IIaA15G2R1 and IIaA16G1R1 were detected as major subtypes, whereas only the IIaA16G1R1 subtype was found in animals kept in boxes. Three of the five detected subtypes were previously associated with human cryptosporidiosis, and moreover, the IIaA15G1R1 subtype, previously reported in humans only, was detected in calves for the first time.

Incoherent neutral pion photoproduction on 12C.

We present the first detailed measurement of incoherent photoproduction of neutral pions to a discrete state of a residual nucleus. The 12C(gamma,pi(0))(12)C*(4.4 MeV) reaction has been studied with the Glasgow photon tagger at MAMI employing a new technique which uses the large solid angle Crystal Ball detector both as a pi(0) spectrometer and to detect decay photons from the excited residual nucleus. The technique has potential applications to a broad range of future nuclear measurements with the Crystal Ball and similar detector systems elsewhere. Such data are sensitive to the propagation of the Delta in the nuclear medium and will give the first information on matter transition form factors from measurements with an electromagnetic probe. The incoherent cross sections are compared to two theoretical predictions including a Delta-hole model.

An assay for the determination of sirolimus levels in the lymphocyte of transplant patients.

UNLABELLED: Both tacrolimus (TAC) and sirolimus (SRL) bind to the same immunophilin FKBP12; however, their mechanisms of action are distinct. SRL inhibits mammalian target of rapamycin (TOR), which is an enzyme critical to the immune function. TOR inhibition blocks the signal that mediates T-cell proliferation by preventing cell-cycle progression from G1 to S phase. Moreover, TOR inhibition results in a decrease in antibody production by blocking B-cell proliferation and maturation into antibody producing cells. The use of SRL has resulted in a decrease in the number of rejection episodes. As with other immunosuppressive agents, SRL can cause dose-related side effects, the most notable of which are hypercholesterolemia, hyperlipidemia, anemia, and thrombocytopenia. Thus, therapeutic drug monitoring to assess efficacy and toxicity has became a necessity. SRL blood levels do not correlate with its bioactivity and are affected by the concomitant use of other immunosuppressive drugs. To determine the bioactivity of SRL we have developed an assay to determine the level of Sirolimus per lymphocyte of transplant patients. The levels were correlated with lymphocyte count. METHODS: Whole blood samples from patients on SRL were collected in Ethylene Diamine Tetra-acetic acid (EDTA) vacutainer tubes. Immediately the lymphocytes from 2 mL of blood were separated using 1.5 mL of Ficoll gradient, by centrifugation for 30 minutes at 2500 RPM. The lymphocytes were washed three times with phosphate-bufferd saline and the pellet suspended in 150 microL of Middle East research institute (MERI) drug extraction solution (Beirut, Lebanon), which was then added to 300 microL of IMx solublizing reagent. The cytoplasmic SRL concentrations in lymphocytes were measured using kits supplied from Abbott diagnostics or by high-performance liquid tomography. A corresponding whole blood sample from each patient was used to measure blood levels. To determine the level per lymphocyte, the value obtained was divided by the number of lymphocytes and expressed as Pg/cell. A pharmacokinetic profile for both blood and lymphocytes was constructed for each patient using data corresponding to predose C(0), 1 hour (C(1)) and 2 hours (C(2)) after the dose. The lymphocyte enumeration for C(0), C(1), and C(2) was performed using the FACS Calibur Flow Cytometer from Becton Dickinson. The average dose was 2.86 +/- 1.27 mg/d with a C(0) = 8.05 +/- 4.24, C(1) = 21.9 +/- 8.9 ng/mL, and C(2) = 23 +/- 0.03 ng/mL. Although there was a significant correlation (P=.0975) between the dose and C(0), there was no correlation between the dose and C(0) level on the lymphocyte count P=.897. However, there was a strong correlation between SRL lymphocyte levels (pg/cell) and the lymphocyte count (r(2)=.6.06). The higher the concentration of the drug the lower the lymphocyte counts. The assay is sensitive to within 0.45 pg/cell, reproducible with a coefficient of variance (CV) of 6.4% within assay and 7.5% for intraassay.

Bioavailability of a new generic formulation of mycophenolate mofetil MMF 500 versus CellCept in healthy adult volunteers.

Several studies have revealed a decreased incidence of early graft rejection with the use of mycophenate mofetil (MMF). The cost of the drug is, however, prohibitive especially in developing countries with limited resources. We compared the pharmacokinetic profile of a new MMF generic formulation (MMF 500 batch number: 06T3001; Medis Tunis) with those of Cellcept, (batch number: M1427; Hoffmann La Roche, Switzerland) in healthy volunteers. The study was double-blinded to investigator and volunteers. It had a balanced randomized, two-treatment, two-period, two-sequence, single-dose, crossover, comparative oral bioavailability design in adult healthy human volunteers. The study was designed, performed, and monitored by CRO Transmedical s.a.l International (Beirut, Lebanon) in accordance with the Basic Principals defined in the US 21 CFR Part 312.20, and the principals enunciated in the World Medical Association Declaration of Helsinki. We included nonsmoking healthy volunteers between the ages of 22 and 45 years. The subjects were admitted to the hospital one night prior to blood sampling. After volunteers received the same dinner, they were fasted overnight and for 2 hours postdosing. At 8 am each person received a single oral dose of 500 mg of either formulation. Blood samples were collected to construct the pharmacokinetic profiles as follows: 0, 0.15, 0.30, 0.45 minutes and 1, 1.15, 1.30, 2, 4, 6, 10, 12, and 24 hours. Water and food intake were the same for all volunteers during the whole study period. Following an 8-day washout period, the subjects were crossed over. Plasma mycophenolic acid concentrations were determined using a high-performance liquid chromatography validated enzyme-linked immunosorbent assay-based method (TransMedical, Beirut Lebanon). Physical examinations, hematology, urinanalysis, serum chemistry tests, and liver enzymes were performed at screening and at the end of each period. Subjects were monitored for safety and adverse events throughout the study by two physicians (one from the hospital and one from TransMedical). The Cmax, Tmax, and AUC for MMF 500 were 10.14 ng/mL, 51.82 minutes, and 18.33 ng/mL/h vs 10.94 ng/mL, 49.09 minutes, and 17.46 ng/mL/h for CellCept, respectively. The 90% confidence intervals (LSM) of Cmax, Tmax, and AUC for MMF 500 were 92.7%, 105.6%, and 105%, respectively, which is within the Food and Drug Administration (FDA)-assigned range for immunosuppressive drugs (90% to 111%). These results indicated that the products are equivalent and switchable according to FDA rulings.