Myonuclear alterations associated with exercise are independent of age in humans.

Age-related decline in skeletal muscle structure and function can be mitigated by regular exercise. However, the precise mechanisms that govern this are not fully understood. The nucleus plays an active role in translating forces into biochemical signals (mechanotransduction), with the nuclear lamina protein lamin A regulating nuclear shape, nuclear mechanics and ultimately gene expression. Defective lamin A expression causes muscle pathologies and premature ageing syndromes, but the roles of nuclear structure and function in physiological ageing and in exercise adaptations remain obscure. Here, we isolated single muscle fibres and carried out detailed morphological and functional analyses on myonuclei from young and older exercise-trained individuals. Strikingly, myonuclei from trained individuals were more spherical, less deformable, and contained a thicker nuclear lamina than those from untrained individuals. Complementary to this, exercise resulted in increased levels of lamin A and increased myonuclear stiffness in mice. We conclude that exercise is associated with myonuclear remodelling, independently of age, which may contribute to the preservative effects of exercise on muscle function throughout the lifespan. KEY POINTS: The nucleus plays an active role in translating forces into biochemical signals. Myonuclear aberrations in a group of muscular dystrophies called laminopathies suggest that the shape and mechanical properties of myonuclei are important for maintaining muscle function. Here, striking differences are presented in myonuclear shape and mechanics associated with exercise, in both young and old humans. Myonuclei from trained individuals were more spherical, less deformable and contained a thicker nuclear lamina than untrained individuals. It is concluded that exercise is associated with age-independent myonuclear remodelling, which may help to maintain muscle function throughout the lifespan.

Nanoparticle Trapping and Characterization Using Open Microcavities.

Characterization and trapping of nanoparticles in solution is of great importance for lab-on-a-chip applications in biomedical, environmental, and materials sciences. Devices are now starting to emerge allowing such manipulations and investigations in real-time. Better insights into the interaction between the nanoparticle and the optical trap is therefore necessary in order to move forward in this field. In this work, we present a new kind of nanotweezers based on open microcavities. We show that by monitoring the cavity mode wavelength shift as the particle diffuses through the cavity, it is possible to establish both the nanoparticle polarizability and its coefficient of friction. Additionally, our experiment provides a deep insight in the interaction between the nanoparticle and the cavity mode. The technique has built-in calibration of the trap strength and spring constant, making it attractive for practical applications. This work illustrates the potential of such optical microcavities for future developments in nanoparticle sensors and lab-on-a-chip devices.

Stable isotope imaging of biological samples with high resolution secondary ion mass spectrometry and complementary techniques.

Stable isotopes are ideal labels for studying biological processes because they have little or no effect on the biochemical properties of target molecules. The NanoSIMS is a tool that can image the distribution of stable isotope labels with up to 50 nm spatial resolution and with good quantitation. This combination of features has enabled several groups to undertake significant experiments on biological problems in the last decade. Combining the NanoSIMS with other imaging techniques also enables us to obtain not only chemical information but also the structural information needed to understand biological processes. This article describes the methodologies that we have developed to correlate atomic force microscopy and backscattered electron imaging with NanoSIMS experiments to illustrate the imaging of stable isotopes at molecular, cellular, and tissue scales. Our studies make it possible to address 3 biological problems: (1) the interaction of antimicrobial peptides with membranes; (2) glutamine metabolism in cancer cells; and (3) lipoprotein interactions in different tissues.

Acute effects of a herb extract formulation and inulin fibre on appetite, energy intake and food choice.

The impact of two commercially available products, a patented herb extract Yerbe Maté, Guarana and Damiana (YGD) formulation and an inulin-based soluble fermentable fibre (SFF), alone or in combination, on appetite and food intake were studied for the first time in a double blind, placebo-controlled, cross-over design. 58 normal to slightly overweight women consumed a fixed-load breakfast followed 4h later by an ad libitum lunch. They were administered YGD (3 tablets) and SFF (5g in 100ml water), YGD and water (100ml), SFF and placebo (3 tablets) or water and placebo 15min before meals. Appetite was assessed using visual analogue scales, and energy intake was measured at lunch. Significant reductions in food intake and energy intake were observed when YGD was present (59.5g, 16.3%; 112.4kcal, 17.3%) and when SFF was present (31.9g, 9.1%; 80kcal, 11.7%) compared with conditions were products were absent. The lowest intake (gram and kcal) was in the YGD+SFF condition. Significant reductions in AUC hunger and AUC desire to eat were also observed after YGD+SFF combination. The data demonstrate that YGD produces a robust short-term effect on caloric intake, an effect augmented by SFF. Caloric compensation for SFF indicates independent effects on appetite regulation.

Intra-operative 3-T MRI for paediatric brain tumours: challenges and perspectives.

MRI is the ideal modality for imaging intracranial tumours. Intraoperative MRI (ioMRI) makes it possible to obtain scans during a neurosurgical operation that can aid complete macroscopic tumour resection­a major prognostic factor in the majority of brain tumours in children. Intraoperative MRI can also help limit damage to normal brain tissue. It therefore has the potential to improve the survival of children with brain tumours and to minimise morbidity, including neurological deficits. The use of ioMRI is also likely to reduce the need for second look surgery, and may reduce the need for chemotherapy and radiotherapy. Highfield MRI systems provide better anatomical information and also enable effective utilisation of advanced MRI techniques such as perfusion imaging, diffusion tensor imaging, and magnetic resonance spectroscopy. However, high-field ioMRI facilities require substantial capital investment, and careful planning is required for optimal benefit. Safe ioMRI requires meticulous attention to detail and rigorous application of magnetic field safety precautions. Interpretation of ioMRI can be challenging and requires experience and understanding of artefacts that are common in the intra-operative setting.

Preparation of location-specific thin foils from Fe-3% Si bi- and tri-crystals for examination in a FEG-STEM.

Bi-crystals and tri-crystals of a nominal Fe-3% Si (wt%) of well-defined orientations have been grown using a floating-zone technique with optical heating. The manufacture of these unique crystals and the preparation technique involved in harvesting thin foils from specific locations for transmission electron microscopy are described in detail. In particular, the grain boundary triple junction has been extracted from the tri-crystal and examined in high-resolution aberration-corrected FEG-STEM instruments. To achieve the necessary resolution, the foils have to be uniformly thin, in the range 50-100 nm over large areas of the specimen. For ferromagnetic materials, there are further challenges arising from the magnetic field interaction, with the electron beam placing significant demands on the aberration correction system. One way to minimise this interaction is to reduce the total mass of magnetic material. To achieve this, an in situ focused ion beam lift-out technique has been combined with an additional precision ion-polishing stage to reproducibly provide thin-foil specimens suitable for high-resolution EELS and EDX analysis. Examination of the foils reveals that the final precision ion-polishing stage removes residual damage arising from the use of focused ion beam milling procedures.

Active GSK3ß and an intact ß-catenin TCF complex are essential for the differentiation of human myogenic progenitor cells.

Wnt-ß-catenin signalling is essential for skeletal muscle myogenesis during development, but its role in adult human skeletal muscle remains unknown. Here we have used human primary CD56Pos satellite cell-derived myogenic progenitors obtained from healthy individuals to study the role of Wnt-ß-catenin signalling in myogenic differentiation. We show that dephosphorylated ß-catenin (active-ß-catenin), the central effector of the canonical Wnt cascade, is strongly upregulated at the onset of differentiation and undergoes nuclear translocation as differentiation progresses. To establish the role of Wnt signalling in regulating the differentiation process we manipulated key nodes of this pathway through a series of ß-catenin gain-of-function (GSK3 inhibition and ß-catenin overexpression) or loss-of-function experiments (dominant negative TCF4). Our data showed that manipulation of these critical pathway components led to varying degrees of disruption to the normal differentiation phenotype indicating the importance of Wnt signalling in regulating this process. We reveal an independent necessity for active-ß-catenin in the fusion and differentiation of human myogenic progenitors and that dominant negative inhibition of TCF4 prevents differentiation completely. Together these data add new mechanistic insights into both Wnt signalling and adult human myogenic progenitor differentiation.

Research collaboration.

The complexity and cost of cardiovascular medical care dictate research to deliver high quality and cost-conscious cardiovascular care. This goal is aided by modeling medical decision making. To be useful, the modeling must be based on real data so that the results can serve as a guide to actual practice. It is suggested that a registry of randomized clinical trials and larger data bases in cardiovascular disease and health care delivery be established. The registry would be a resource for those desiring to model decision making. The registry would contain key words allowing retrieval by modelers accessing the registry and would contain contact information for consideration of possible collaborative work. The initiation of such a registry should contain plans for its evaluation to determine whether the registry itself is a cost-effective tool to encourage the needed research.

Colposcopy information leaflets: what women want to know and when they want to receive this information.

OBJECTIVES: To evaluate whether the information leaflets produced by UK colposcopy clinics provide women with the information they desire and to determine when they would like to receive this information. DESIGN: Questionnaire study and structured evaluation. SETTING: The colposcopy clinic of a UK cancer centre. PARTICIPANTS: Forty-two women attending a pre-colposcopy counselling session and 100 consecutive women attending the colposcopy clinic. METHODS: Thirty-eight standards derived from the concerns/questions asked by women attending a pre-colposcopy counselling session were used to assess locally produced colposcopy clinic leaflets from UK colposcopy clinics, the leaflets produced by the Royal College of Obstetricians and Gynaecologists and the National Health Service Cervical Screening Programme (NHSCSP), and two "leaflets" obtained from internet sites. The Gunning fog test was used to assess the leaflets' readability. A questionnaire survey of 100 women attending the colposcopy clinic was used to determine when women wanted to receive information about colposcopy. MAIN OUTCOME MEASURES: Percentage of questions answered by a given leaflet and Gunning fog scores for readability. RESULTS: The information leaflets of 128 colposcopy clinics were received and assessed. Thirty-two clinics only sent women the NHSCSP leaflet. No leaflet answered all 38 questions. Less than half (36/100) of the leaflets answered more than 50% of the questions. In addition to the lack of advice given, different leaflets frequently gave conflicting advice. The average Gunning fog score was 9.7 (range 5.5-15.5). The majority of women (70%) wanted to receive information about colposcopy at or prior to the time of receiving their abnormal smear test result, although only 42% of women actually received information at this time. CONCLUSIONS: Many UK colposcopy clinics do not appear to be providing women with the information they require to understand their condition and the procedure that they are about to undergo. Furthermore, this information is often not provided at the appropriate time in the screening process.

Visualization of layers lining the lung of the South American lungfish (Lepidosiren paradoxa) and a comparison with the frog and rat.

Comarisons have been made of the structure of layers lining the lungs of lungfish, frog and rat using material fixed by perfusion of the pulmonary circulation of physiological pressures and at normal air pressures within the lung. The lining consists of a thin densely osmiophilic surface layer which covers a much thicker hypophase of generally floccular appearance. Tubular myelin, present in the frog and rat lung lining, was not observed in the layers lining the lung of Lepidosiren.

Effects of temperature and transfer from seawater to freshwater on blood microrheology in Pacific salmon.

Blood of Pacific salmon was studied with particular interest in red blood cell (RBC) deformability in relation to migration. Blood samples were taken via cardiac puncture or chronic cannula placed in the dorsal aorta and heparinized. As an index of RBC deformability the mean passage time of single RBCs through micropores of 8 micron in diameter and 10 micron in length was determined under a pressure difference of 10 cmH2O. Despite about 100 mOsmol/l difference in plasma osmolality, there was no marked difference in RBC passage time between fish in seawater and those well acclimatized to freshwater. However, it seemed probable that a transient decrease in RBC passage time, i.e., an increase in RBC deformability, occurred immediately following transfer from seawater to freshwater. Plasma osmolality decreased to about 300 mOsmol/l within 1 hr after the transfer and showed no fluctuations thereafter. The temperature dependence of RBC deformability was much smaller in comparison with those previously observed in yellowtail and carp; salmon RBCs were still highly deformable even at 5 degrees C, a possible temperature of cold river water.

Effects of low pH alone and combined with copper sulphate on blood parameters of rainbow trout.

Copper sulphate (0.2 ppm) has only a slight damaging effect on tissues as indicated by measurements of biochemical and haematological parameters. These effects are significantly increased in the presence of sulphuric acid at pH 6.5.

The effect of copper sulphate on some biochemical parameters of rainbow trout.

Copper sulphate has an adverse effect on some biochemical parameters of trout Salmo gairdneri. The main targets of damage are: (a)Tissue necrosis as demonstrated by increased ASAT and ALAT levels in blood plasma. (b)Inhibition of acetylcholinesterase activity. There is also a general stress effect as reflected by an elevated blood glucose level.

Effects of low environmental pH in the presence of aluminum on filtration properties of the blood of atlantic salmon (Salmo salar L.).

The time for filtration of whole blood samples through 8 microns pores of polycarbonate membranes provides an index of the deformability of fish red blood cells. Comparison of these and other haematological measurements on salmon before and after exposure to pH 5.0 and 20 microM aluminium for 2 hours shows changes which are indicative of hypoxia. The increase in deformability of the red cells will assist transfer of oxygen from the gills to the tissue cells and hence compensate environmental hazards of low pH and aluminium.

The influence of red cell size relative to pore size on filtration through nuclepore filters.

A simple model relating pore passage time (PPT) to the degree of strain of the membrane of a red cell of diameter DC on passing through a pore (diameter Dp) has been developed. The model was tested for a range of mammalian and fish species for which some data was available for more than one pore size. The strain (epsilon) is estimated as (Dc-Dp)/Dc. For small epsilon, less than approximately 0.45, PPT was small but rose rapidly for higher values. The analysis provides a simple basis for choosing appropriate pore sizes, and consequently strain, for comparing mechanical properties of erythrocytes of different species.

Swimming performance of rainbow trout following exposure and recovery from the pyrethroid S-deltamethrin.

Oxygen consumption and swimming performance of rainbow trout exposed to sublethal concentrations (10-50 microliters/20 L) of pyrethroid (S-deltamethrin) pesticide was studied in a Brett-type respirometer during recovery. Results showed wide variations reflecting the varied responses of different individual fish to the test regime. In most cases values of oxygen consumption for the controls were higher at each swimming speed and this became significantly reduced following treatment with pesticide. Oxygen consumption soon after the treatment gave the highest values but these fish were unable to sustain swimming speeds as high as the controls or following recovery. The comparisons of swimming performance before and after treatments with deltamethrin have shown a significant effect on locomotory ability of rainbow trout which at the end of strong exposure (e.g. 50 min of 40 microliters/20 L) are almost incapable of swimming.

Routine oxygen consumption in different sizes of a tilapia, Oreochromis niloticus (Trewavas) using the closed chamber respiratory method.

Routine oxygen consumption (Vo2) measurements on 54 specimens (0.055-190.4 g) of a tilapia, Oreochromis niloticus (Trewavas) were carried out using two different types of closed respirometers: a modified cuvette for fish weighing 0.055-0.91 g and ordinary closed chamber respirometer for fish weighing more than 1 g. Vo2 values over the weight range studied had a scaling value of 0.743 which relates closely to the values for the gill respiratory surface area and morphometric oxygen diffusing capacity of O. niloticus in a previous study /13/. This shows that a close relationship exists between changes in structural parameters involved in oxygen uptake and the routine metabolism of O. niloticus with development. The values for routine Vo2 of 1.38 and 7.65 ml/h for 10 g and 100 g fish, respectively (calculated from the regression equation) show that O. niloticus is a moderately active fish.

Recovery of cardiac and ventilatory frequencies after sub-acute pesticide (ABOL-X) treatment in rainbow trout, Salmo gairdneri Richardson.

Short term, sublethal changes in coughing rate, cardiac and ventilatory frequencies in hatchery-reared rainbow trout (27-34 cm) exposed to menazon and gamma BHC containing pesticide were monitored at 15 +/- 1 degree C during recovery period to investigate the effects of this chemical on fish respiratory and cardiovascular systems. Laboratory conditions simulated a rapid environmental pollution often occurring in running waters. The coughing response was particularly sensitive to water pollutants. Average rate of ventilation was lower in treated fish than in control specimens and decreased parallel with the time of recovery. Average heart rate was higher in treated trout as compared to the controls. These changes were characteristic for hypoxic conditions and provide useful sublethal physiological indications for a rapid environmental stress. Percentage coupling and phase angle of ECGs within the ventilatory cycle were also studied during recovery when significant differences were observed between treated and untreated groups of fish.

A comparison of blood composition in the common carp (Cyprinus carpio L.) using samples obtained from caudal vessels and dorsal aorta cannulae.

Blood samples have been taken from chronic cannulae in the dorsal aorta of Carp under anaesthesia and at intervals of 24, 29 and 101 hours later. A few minutes after the 29 hours and 101 hours sampling was completed similar quantities (1 ml) were withdrawn from a caudal vessel. All samples were treated in the same way and determinations made of haematocrit value, total protein, glucose concentration and activity of the following plasma enzymes-acetylcholinesterase (AChE), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) and lactic dehydrogenase (LDH). Comparisons between dorsal aorta and caudal samples at 29 hours and 101 hours showed no significant differences for any of the enzyme activities that were tested. However significant (paired "t"-test, P < 0.05) differences were observed for haematocrit and glucose concentration. It is suggested that the higher haematocrit and lower glucose of caudal samples are consistent with the expected differences between arterial and venous blood. Apart from these differences which reflect normal physiological function, values obtained for samples from the two sites were identical. It is concluded that blood sampling from caudal vessels is a satisfactory method to obtain blood for biomonitoring purposes at least for those enzymes commonly used in recent surveys.

Study of the effects of brief exposure to an organophosphorous insecticide (methidathion) on blood characteristics of carp (Cyprinus carpio).

1. Carp with the dorsal aorta cannulated have been used to study the effects of a 5 hour exposure to methidathion at concentrations of 2 or 6 mg/litre. Blood samples taken during control, exposed and recovery periods were used to determine plasma acetylcholinesterase (AChE) activity, haematocrit value, mean cell volume, total plasma protein, and filtration time through Nucleopore filters containing pores of 8 microns. 2. A drastic inhibition of AChE activity was observed and this continued during the recovery for at least 5 days. Changes in other blood parameters were less marked and recovered soon after fish were returned to non-polluted water. The increased haematocrit and decrease in filtration time suggests some impairment of gas transfer during exposure but the depletion of AChE activity and associated muscular and neural disturbances are more serious results of pollution with this organophosphate insecticide.