Histochemical Properties of Fast Twitch Muscle in the Rat

A histochemical study of muscle fibers comprising the extensor digitorum longus muscle of adult female Wistar rats was carried out in which Acid ATPase, Alkaline ATPase, Phosphorylase and SDHase determinations were used to classify muscle fibers. On the basis of Alkaline and Acid ATPase determinations three classes of muscle fibers were determined, Dark, Intermediate and Light, respectively. On the basis of Phosphorylase and SDHase, two classes of muscle fibers were found, classed as Dark and Light fibers. Therefore fibers could be identified within the muscle of 13 different types. An analysis of the muscle on this basis is compared with that of other muscles in the rat and with muscles of other species studied with either cytochemical or physiological techniques.     

Use of BACTEC radiometric culture method and polymerase chain reaction for the rapid screening of faeces and tissues for Mycobacterium paratuberculosis

SUMMARY The BACTEC radiometric culture method for detection of Mycobacterium paratuberculosis was evaluated on faeces from cattle on a farm in quarantine for Johne's disease. A multiplex polymerase chain reaction (PCR) based on the IS900 sequence specific for M paratuberculosis and a genus specific 16S rRNA region was developed and used to test cultures showing evidence of mycobacterial growth in the BACTEC liquid radiometric culture medium. Using the BACTEC - PCR combination, confirmation of M paratuberculosis from faeces and tissue of clinically affected animals was achieved within 2 to 4 weeks and 1 week, respectively, a substantial improvement on traditional culture and identification methods. The PCR provided rapid exclusion of M paratuberculosis when other Mycobacterium spp were grown. The radiometric culture medium proved to be very sensitive for culturing Mycobacterium spp.     

L7-S1 fixation-fusion for treatment of cauda equina compression in the dog

The L7-S1 fixation-fusion technique for treatment of cauda equina compression was performed on 14 dogs, 13 of which were 6 years old or older, were severely lame, and had ventral bridging spondylitis at the L7-S1 vertebrae. One dog, 3 months old, had a congenital malformation of the L7 vertebra. The principles of the L7-S1 fusion technique were to expand the L7-S1 intervertebral foramina and spinal canal, remove pressure on the nerve roots, and provide stability to the L7-S1 vertebrae. This technique appeared to be applicable clinically for restoring normal function and activity to dogs with cauda equina compression.     

Electroencephalograms and electrocardiograms in young bulls following upper cervical vertebrae-to-brisket stunning

Passing an electric current (50 Hz, 400 V open circuit, current limited to 1.5 A) from two electrodes acting as a common single electrode set applied on each side of the dorsal surface of the neck (cervical vertebrae C2 to C5 region) to another placed on the brisket of young bulls causes fibrillation of the cardiac muscle, does not induce epileptiform changes in the electroencephalogram, and produces a state of body rigidity. Passing the same electric current through the same neck electrodes, now acting as two separate electrodes, without the brisket electrode, does induce epileptiform activity similar to that seen with head-only stunning, does not fibrillate the heart, and produces a state of limb rigidity lasting for some time after the stun. Given that the presence of epileptiform activity is a criterion for effective electrical stunning and is indicative of insensibility, neck-to-brisket stunning as described here does not appear to be humane.     

Intra-annual growth and mortality of four <Emphasis Type="Italic">Populus</Emphasis> clones in pure and mixed plantings

Intra-annual growth rates were assessed during 3 years for four Populus clones grown in pure and mixed clonal stands at square spacings of 0.5, 1.0 and 1.5 m in western Washington, USA. Height growth rate peaked in August, except at the 0.5-m spacing where it peaked in July and June in years 2 and 3, respectively. Diameter growth rate generally peaked in June. Seasonal growth patterns in mixed clonal stands, relative to those in pure clonal stands, varied by clone. Following early season moisture stress in year 2, growth of a P. balsamifera ssp. trichocarpa clone declined significantly relative to three P. balsamifera ssp. trichocarpa × P. deltoides clones; this trend was most evident at the 0.5-m spacing. During this period of moisture stress, P. balsamifera ssp. trichocarpa had 11 and 36% mortality in pure and mixed stands, respectively, at the 0.5-m spacing; this clone had no mortality at wider spacings during the same period. Although height rankings among clones shifted during the first growing season, rankings at the end of year 1 were very similar to those at the end of year 3.     

Bending Characteristics of Polymethylmethacrylate Columns,Connecting Bars of Carbon Fiber,Titanium, and Stainless Steel Used in External Skeletal Fixation and an Acrylic Interface

Objective: To (1) mechanically evaluate polymethylmethacrylate (PMMA) columns of various sizes and compare them to connecting bar materials (carbon fiber composite, titanium, stainless steel) and (2) compare the properties of an intact PMMA column to those of an acrylic interface. Study Design: Experimental mechanical study. Sample Population: Experiment 1: 6 groups of 6 specimens each; experiment 2: 2 groups of 12 specimens each. Methods: All specimens were tested in 3‐point bending. Stiffness, yield strength, and ultimate strength values were calculated for each specimen. Results: PMMA 1 columns (23.25 mm) compared favorably to titanium or stainless‐steel bars. PMMA 3 columns (30.15 mm) and carbon fiber bars had similar yield strength but PMMA 3 columns were less stiff than carbon fiber bars. PMMA 3 columns had lower bending modulus and a higher variability in their mechanical properties than PMMA 1 or PMMA 2 (25.64 mm) columns. Acrylic interface specimens were less strong but as stiff as intact specimens. Conclusion: An acrylic interface was easily created and had acceptable biomechanical characteristics. Clinical Relevance: PMMA 2 and PMMA 3 columns are not recommended for clinical use at this time. Further tests are needed to analyze an acrylic patch in a more clinically relevant loading model.     

Visualization of three-dimensional chaos

Most chaotic mixing experiments have been restricted to two-dimensional, time-periodic flows, and this has shaped advances in theory as well. A prototypical, bounded, three-dimensional flow with a moderate Reynolds number is presented; this system lends itself to detailed experimental observation and allows for high-precision computational inspection. The flow structure, captured by means of cuts with a laser sheet (experimental Poincare section), was visualized with the use of continuously injected fluorescent dye streams and revealed detailed chaotic structures with high-period islands.