Use of Cryogenically Prepared Samples in the Scanning Electron Microscopic Study of Dry-to-Wet Transitions

Cryogenic preparation has been used to study changes that occur as a dry specimen undergoes hydration. Conventional techniques such as critical point drying or anhydrous fixation are unsuitable for studying such changes. Seed tissue, a dry moss and various foods were chosen to show dry-to-wet transitions that take place after wetting of the dry sample begins. Cryogenically prepared specimens have great potential, not only in the study of changes which occur during imbibition of one sample, but also in the study of samples with different moisture content

Beam Sensitivity of Globoid Crystals within Seed Protein Bodies and Commercially Prepared Phytates During X-Ray Microanalysis

Magnesium, potassium, calcium and phosphorus are stored in seed tissues in spherical particles called globoid crystals. The main component of globoid crystals is phytin, a salt of myo-inositol hexaphosphoric acid. Based on chemical similarity, commercially available phytates may be suitable standards for quantitative energy dispersive X-ray (EDX) microanalysis of globoid crystals. The stability of globoid crystals and commercial phytates was different when analyzed under identical conditions. Phytates in globoid crystals from Cucurbita maxima cotyledons, were relatively stable in the electron beam during EDX microanalysis at room temperature, but there was a loss of potassium. No loss of potassium occurred during analysis at low temperature, even with repeated analyses on the same spot. Commercial phytates showed considerable beam damage in the form of raised mounds at the sites of analyses. The extent of the damage was much reduced with analysis at low temperature. Although there was some variation in the peak-to-background ratios of potassium and sodium with various analytical conditions, there was no differential loss of potassium or sodium as occurred with EDX analysis of globoid crystals. Reasons for differences between in situ and isolated phytates are unclear. Provided analyses are carried out at low temperature, commercial phytates have potential as standards but further research is required to determine how to control moisture content during sample preparation and analysis

Cell Wall Wrinkling and Solute Leakage in Imbibing Squash and Carrot Seeds

Dry seeds placed in an aqueous solution take up water, swell, and leak potassium and a variety of other materials into the solution. It is likely that much of the potassium is from the cell walls. Neutron activation analysis was used to measure the concentration of potassium leaked from both squash embryos and carrot mericarps that had been soaked in solutions of different water content. The cell walls in dry seed tissues are often wrinkled, whereas imbibed tissues have smooth cell walls. Cryogenic preparation for scanning electron microscopy was used to study the degree of cell wall wrinkling in the seed tissues at different hydration levels. The aim of this study was to test the hypothesis that the degree of cell wall wrinkling was related to the leakage of potassium. It was found that the amount of potassium leaked into the soaking solutions was not directly related to the degree of wrinkling of the cell walls

Use of conventional and alternative treatment strategies for a case of low back pain in a F/A-18 aviator

BACKGROUND: Low back pain can diminish jet pilot concentration and function during flight and be severe enough to ground pilots or cause decreased flying time. The objective of this case report is to present an example of the integration of chiropractic care with conventional treatments for the management of low back pain in a F/A-18 aviator. CASE PRESENTATION: The patient had insidious severe low back pain without radiation or neurological deficit, resulting in 24 hours of hospitalization. Spinal degeneration was discovered upon imaging. Four months later, it still took up to 10 minutes for him to get out of bed and several minutes to exit the jet due to stiffness and pain. He had discontinued his regular Marine Corps fitness training due to pain avoidance. Pain severity ranged from 1.5–7.1 cm on a visual analog scale. His Roland Morris Disability Questionnaire score was 5 out of 24. The pilot's pain was managed with the coordinated efforts of the flight surgeon, physiatrist, physical therapist, and doctor of chiropractic. Following this regimen he had no pain and no functional disability; he was able to fly multiple training missions per week and exercise to Marine Corps standards. CONCLUSION: A course of care integrating flight medicine, chiropractic, physical therapy, and physiatry appeared to alleviate pain and restore function to this F/A-18 aviator with low back pain

Effects of Neonatal Neural Progenitor Cell Implantation on Adult Neuroanatomy and Cognition in the Ts65Dn Model of Down Syndrome

As much of the aberrant neural development in Down syndrome (DS) occurs postnatally, an early opportunity exists to intervene and influence life-long cognitive development. Recent success using neural progenitor cells (NPC) in models of adult neurodegeneration indicate such therapy may be a viable option in diseases such as DS. Murine NPC (mNPC, C17.2 cell line) or saline were implanted bilaterally into the dorsal hippocampus of postnatal day 2 (PND 2) Ts65Dn pups to explore the feasibility of early postnatal treatment in this mouse model of DS. Disomic littermates provided karyotype controls for trisomic pups. Pups were monitored for developmental milestone achievement, and then underwent adult behavior testing at 14 weeks of age. We found that implanted mNPC survived into adulthood and migrated beyond the implant site in both karyotypes. The implantation of mNPC resulted in a significant increase in the density of dentate granule cells. However, mNPC implantation did not elicit cognitive changes in trisomic mice either neonatally or in adulthood. To the best of our knowledge, these results constitute the first assessment of mNPC as an early intervention on cognitive ability in a DS model

Teleconnections of the Quasi‐Biennial Oscillation in a multi‐model ensemble of QBO‐resolving models

The Quasi-biennial Oscillation (QBO) dominates the interannual variability of the tropical stratosphere and influences other regions of the atmosphere. The high predictability of the QBO implies that its teleconnections could lead to increased skill of seasonal and decadal forecasts provided the relevant mechanisms are accurately represented in models. Here modelling and sampling uncertainties of QBO teleconnections are examined using a multi-model ensemble of QBO-resolving atmospheric general circulation models that have carried out a set of coordinated experiments as part of the Stratosphere-troposphere Processes And their Role in Climate (SPARC) QBO initiative (QBOi). During Northern Hemisphere winter, the stratospheric polar vortex in most of these models strengthens when the QBO near 50 hPa is westerly and weakens when it is easterly, consistent with, but weaker than, the observed response. These weak responses are likely due to model errors, such as systematically weak QBO amplitudes near 50 hPa, affecting the teleconnection. The teleconnection to the North Atlantic Oscillation is less well captured overall, but of similar strength to the observed signal in the few models that do show it. The models do not show clear evidence of a QBO teleconnection to the Northern Hemisphere Pacific-sector subtropical jet