ABSTRACT
The viscoelastic properties of normal and surgically altered lumbar intervertebral disks from eight immature swine were examined in vivo. Rheological models were used to mathematically characterize the compressive creep-relation behavior of the disks before and after alteration by either chemonucleolysis [chymopapain (Chymodyactin) injection] or denucleation. In the normal disks, a significant modulating effect of respiration was observed that tended to increase the creep deformation response in comparison to that observed during similar in vitro and in situ studies. These results suggest that, in terms of assessing the absolute magnitude of the viscoelastic properties of lumbar disks, the influence of normal physiological function on adjacent vertebrae and surrounding tissues cannot be neglected. Preliminary results obtained from the experimentally altered disks indicated that partial denucleation primarily affected the initial stiffness behavior of the disk (24% decrease in elastic modulus), whereas chemonucleolysis caused changes in both the time-dependent (15% increase in creep rate) and instantaneous (23% decrease in elastic modulus) properties of the disk. Both partial denucleation and acute chemonucleolysis produced biomechanical changes that were comparable to grade II or slightly degenerative, age-related changes found in human lumbar intervertebral disks.
Subject(s)
Intervertebral Disc , Lumbar Vertebrae , Spinal Diseases/physiopathology , Animals , Biomechanical Phenomena , Chymopapain/pharmacology , Elasticity , Intervertebral Disc/surgery , Intervertebral Disc Chemolysis , Models, Biological , Radiography , Reference Values , Respiration , Spine/diagnostic imaging , Spine/drug effects , Swine , ViscosityABSTRACT
After an extensive examination of the release rates and blend ratios of pheromonal components emitted by field-collected femalePectinophora gossypiella (Saunders), we find no evidence of resistance to pheromones applied to cotton fields to disrupt mating. Females from fields with 3-5 years of exposure to disruptant pheromones as well as those from fields with only minimal exposure to disruptant pheromones emitted (Z,Z)-7,11-hexadecadienyl acetate at a rate of ca. 0.1 ng/min and (Z,E)7,11-hexadecadienyl acetate at ca. 0.06 ng/min. The ratio of pheromonal components was much less variable than the measured emission rate and was centered about a 61:39Z, Z to Z,E ratio. In contrast to the blend ratio emitted by females, the composition of the pheromonal blend used in monitoring populations and disrupting mating is centered about 50:50 Z,Z to Z.E. In general there was a remarkable consistency in the release rate and blend ratio among populations of females throughout southern California and those from a laboratory colony. It would appear that, although resistance to theP. gossypiella pheromone is still a very real possibility when it is used heavily in pest management as a mating disruptant, there are current agricultural practices and conditions which would hinder its development.
ABSTRACT
Sex pheromone gland volatiles from individualHeliothis virescens (F.) females were collected and analyzed on an SP-2330 capillary gas-liquid chromatography column for identification and quantification of the compounds emitted. Only four of the seven compounds previously reported as pheromone components appeared consistently in the volatile collections: 14:Ald, Z9-14:Ald, 16:Ald, and Z11-16:Ald. The female glands did not emit the same amounts of these compounds throughout a 24-hr period; they emitted maximum quantities between 6 and 11 hr after the onset of scotophase with the remainder of the photoperiod having minimal emission rates. Although the absolute quantities fluctuated, the percent compositions of the compounds remained about the same throughout the 24-hr period.
ABSTRACT
A high-efficiency collection device for sex pheromones volatized from forcibly extruded female glands is described. Filtered nitrogen gas is the carrier and glass wool the adsorbent. Small quantities of distilled carbon disulfide are used to rinse the glass wool. Recovery efficiency of synthetic compounds was usually 90-100%, and a mean of 2.4 ± 0.65 SD ng/min of (Z)-7-dodecenyl acetate was recovered in emissions from individualTrichoplusia ni (Hubner) glands.
