Long-term blood-sampling technique in piglets

A technique to enable long-term blood sampling from piglets aged 2-3 months is described. Piglets were housed individually in expandable cages and a heparinized polyurethane catheter was inserted into the external jugular vein. A technique was used which prevented the catheter from pulling out of the vein with growth of the animals. Blood samples could be obtained for more than 1 month, and levels of cortisol, glucose, white blood cell count, haematocrit, rectal temperature and heart rate were compared for samples obtained from simulated conventional venopunctures and from the cannula using this technique. It was shown that restraint and needle pricks raised these levels considerably.     

Validation of a non-invasive fluoroscopic imaging technique for the measurement of dynamic knee joint motion

The accurate measurement of the in vivo knee joint kinematics in six degrees-of-freedom (6DOF) remains a challenge in biomedical engineering. We have adapted a dual fluoroscopic imaging system (DFIS) to investigate the various in vivo dynamic knee joint motions. This paper presents a thorough validation of the accuracy and repeatability of the DFIS system when used to measure 6DOF dynamic knee kinematics. First, the validation utilized standard geometric spheres made from different materials to demonstrate the capability of the DFIS technique to determine the object positions under changing speeds. The translational pose of the spheres could be recreated to less than 0.15±0.09 mm for velocities below 300 mm/s. Next, tantalum beads were inserted into the femur and tibia of two fresh frozen cadaver knees to compare the dynamic kinematics measured by matching knee models to the kinematics from the tantalum bead matching—a technique similar to Roentgen stereophotogrammetric analysis (RSA). Each cadaveric knee was attached to the crosshead of a tensile testing machine and vertically translated at a rate of 16.66 mm/s while images were captured with the DFIS. Subsequently, the tibia was held fixed and the femur manually flexed from full extension to 90° of flexion, as the DFIS acquired images. In vitro translation of the cadaver knee using the tensile testing machine deviated from predicted values by 0.08±0.14 mm for the matched knee models. The difference between matching the knee and tantalum bead models during the dynamic flexion–extension motion of the knee was 0.1±0.65°/s in flexion speed; 0.24±0.16 mm in posterior femoral translation; and 0.16±0.61° in internal–external tibial rotation. Finally, we applied the method to investigate the knee kinematics of a living subject during a step ascent and treadmill gait. High repeatability was demonstrated for the in vivo application. Thus, the DFIS provides an easy and powerful tool for accurately determining 6DOF positions of the knee when performing daily functional activities.     

Mechanography: a non-invasive technique for the evaluation of cardiac function in children

Experience in the pediatric age group with mechanography, an indirect method of cardiovascular investigation, is described with emphasis on the recording technique and on the analysis of the tracings. A few examples are presented with comments on the morphological aspects and the time characteristics of the pulse curves, showing how much information about cardiac disease and especially myocardial function in children may be obtained.     

Validation of the doubly labeled water technique for measuring energy metabolism in starlings and sparrows

I have tested the idea that doubly labeled water (DLW) can accurately predict CO2 production in savannah sparrows, song sparrows, white-throated sparrows, starlings, and a single house sparrow by comparing DLW estimates with those obtained simultaneously by capturing expired CO2 in Ascarite. In addition I used the energy balance method to see if metabolic rates generated from DLW measurements accurately reflected the actual metabolic rates of these birds. I found close agreement in DLW and the gravimetric and energy balance methods, with DLW underestimating CO2 production on average by -3.5% in sparrows, and -7.1% in starlings. Similarly, the energy balance method indicated a -3.1% underestimate by DLW for sparrows and a -5.1% for starlings. The DLW method can yield reasonable estimates of CO2 production in a variety of passerine birds.     

Validation of a calibration technique for 6-DOF instrumented spatial linkages

This paper presents a practical and effective approach to the calibration of instrumented spatial linkages for biomechanical applications. A 6-DOF mechanical linkage with rotational transducers is designed and in-house manufactured for this purpose. In order to assess the validity of the proposed calibration technique and to distinguish between geometrical and electrical parameters uncertainties, high-precision optical encoders are used and calibration is addressed from a kinematic point of view only. The proposed technique is based on a closed-loop method, in which the end segments of the linkage are connected to each other by revolute joints. A parametrical model of the system is formulated using a standard link-to-link transformation matrices approach. Continuous data collection is carried out and a recursive identification of kinematic parameters is implemented by the use of an extended Kalman filter algorithm. Results shows that the proposed technique, despites its simplicity, is effective in improving the accuracy of the system up to its theoretically computed resolution, which limits the performance of the real system.     

A non-invasive technique for identifying individual badgers Meles meles

Individual badgers Meles meles can be reliably identified in the field on the basis of variation in the appearance of the tail. Tests of the technique using video surveillance demonstrated that in 95% of instances individuals were identified correctly on the basis of tail patterns. It is possible that tail patterns and posture may be a significant means of communication in this species.     

A non-invasive technique for quantifying and isolating fused cells

Cell–cell fusion is an important biological and pathological event. There are limited techniques for studying both the process of cell–cell fusion and the fate of fused cells. We have developed a non-invasive assay for the temporal analysis of cell–cell fusion, quantification of fused cells, and isolation of fused cells. Briefly, cells are transfected with either the T7 bacteriophage RNA polymerase, or yellow fluorescent protein (YFP) driven by a T7 specific promoter. Cells are mixed and induced to fuse. When cells expressing T7 RNA polymerase and T7 promoter driven YFP (T7-YFP) fuse and the cellular contents mix, the YFP is expressed. These YFP-positive cells can be detected with a fluorescent microscope, quantified by flow cytometry, or collected using fluorescence associated cell sorting. Isolated YFP-positive cells can be monitored to determine the fate of fused cells, specifically for the rates of growth, transformation, and changes in chromosome number.     

Canadian recommendations underestimate energy needs of women over fifty years as determined by doubly-labelled water

Accurate estimations of energy requirements at the population level are crucial because of disease processes associated with energy imbalance. The present objective was to compare energy expenditure with existing Recommended Nutrient Intakes for Canadians (RNIC) and determine whether the RNIC provides a true index of energy requirement in middle-aged and elderly Canadian women. A second objective was to compare energy expenditure and the RNIC to Food and Agriculture Organization, World Health Organization, United Nations University (FAO/WHO/UNU) predictions. Seventy-six women were recruited for the study (67.3 +/- 11.5 y, 63 +/- 11.7 kg, BMI 24.8 +/- 4.4 kg x m(-2)). The two-point doubly-labelled water (DLW) method was used over 13 days to assess energy expenditure while subjects carried out their routine activities. Subjects were stratified to enable age specific requirements for middle-aged and elderly women. At weight maintenance, energy needs were underestimated using the RNIC (7.1 +/- 1.6 MJ x d(-1), 1698 +/- 391 kcal x d(-1)) compared to total energy expenditure (10.0 +/- 3.2 MJ x d(-1), 2395 +/- 746 kcal x d(-1)) as determined by DLW as a whole and for each age group. The RNIC recommendations were lower than the FAO/WHO/UNU estimations even for light activity. Results indicate that mean energy expenditure was 29% greater than the RNIC recommendations created using formulas based on age and weight, whereas the FAO/WHO/ UNU estimations closely approximated energy expenditure based on heavy activity in women 49-79 y and light activity in women over 80 y old. These data suggest a systematic underestimation of Canadian energy recommendations for women.     

Validation of swabs as a non-destructive and relatively non-invasive DNA sampling method in fish

Non-destructive methods of collecting DNA from small fish species can be problematic, as fin clips can potentially affect behaviour or survivorship in the wild. Swabbing body mucus may provide a less invasive method of DNA collection. However, risk of contamination from other individuals in high density groups could give erroneous genotyping results. We compared multilocus microsatellite genotypes from the same individuals when collected at low and high density and compared this with fin clips. We found no differences between these categories, with a genotyping error rate of 0.42%, validating the use of body mucus swabbing for DNA collection in fish.     

A non-invasive technique for rapid extraction of DNA from fish scales

DNA markers are being increasingly used in studies related to population genetics and conservation biology of endangered species. DNA isolation for such studies requires a source of biological material that is easy to collect, non-bulky and reliable. Further, the sampling strategies based on non-invasive procedures are desirable, especially for the endangered fish species. In view of above, a rapid DNA extraction method from fish scales has been developed with the use of a modified lysis buffer that require about 2 hr duration. This methodology is non-invasive, less expensive and reproducible with high efficiency of DNA recovery. The DNA extracted by this technique, have been found suitable for performing restriction enzyme digestion and PCR amplification. Therefore, the present DNA extraction procedure can be used as an alternative technique in population genetic studies pertaining to endangered fish species. The technique was also found equally effective for DNA isolation from fresh, dried and ethanol preserved scales.     

A non-invasive technique for cell volume determination in perfused rat liver

1) In isolated perfused rat liver, the intracellular ([14C]urea-accessible minus [3H]inulin accessible) water space was determined from the washout profiles of simultaneously infused [3H]inulin and [14C]urea. The washout profile of infused [14C]urea was indistinguishable from that of infused tritiated water. During normotonic perfusions and without hormones or amino acids in influent, the intracellular water space was 548 +/- 10 microliters/g liver wet weight (n = 44). Use of [3H]raffinose instead of [3H]inulin as marker for the extracellular space yielded almost identical values for the intracellular water space (i.e. 98.9 +/- 0.2% of that found with [3H]inulin/[14C]urea). When volume-regulatory K+ fluxes were completed following hypo- and hypertonic exposure of perfused rat livers and a steady state was reached, the intracellular water space was found to be increased and decreased, respectively. The extent of anisotonic exposure was linearly related to the change of intracellular water space. 2) Anisotonicity-, glutamine- and glycine-induced liver mass changes were almost fully explained by the simultaneously occurring alterations of the intracellular water space, indicating that cell volume changes in perfused rat liver under these conditions are not accompanied by significant changes of the extracellular space. Volume-regulatory K+ (plus accompanying anion) efflux following hypotonic perfusion accounted for about 70-85% of regulatory cell volume decrease, which occurred during the first 10 min of hypotonic exposure. 3) Cell volume of isolated hepatocytes was determined as the "hepatocrit" after gentle centrifugation of the cell suspension.(ABSTRACT TRUNCATED AT 250 WORDS)     

A non-invasive laser technique for characterisation of hybridoma suspensions in stirred vessels

Summary A novel optical method based on the analysis of the radial light intensity profile from a Laser source (HeNe 632.8 nm) is proposed and its use with hybridoma cells in suspension described. The technique enables direct determination of extinction (α) and scattering coefficient at 90 degrees (β) of the suspension, which are shown to vary during a batch culture and under different agitation conditions.