The potential of cationic SiO2 nanoparticles was investigated for in vivo gene transfer in this study. Cationic SiO2 nanoparticles with surface modification were generated using amino-hexyl-amino-propyltri-methoxysilane (AHAPS). The zeta potential of the nanoparticles at pH = 7.4 varied from -31.4 mV (unmodified particles; 10 nm) to +9.6 mV (modified by AHAPS). Complete immobilization of DNA at the nanoparticle surface was achieved at a particle ratio of 80 (w/w nanoparticle/DNA ratio). The surface modified nanoparticle had a size of 42 nm with a distribution from 10-100 nm. The ability of these particles to transfect pCMVbeta reporter gene was tested in Cos-1 cells, and optimum results were obtained in the presence of FCS and chloroquine at a particle ratio of 80. These nanoparticles were tested for their ability to transfer genes in vivo in the mouse lung, and a two-times increase in the expression levels was found with silica particles in comparison to EGFP alone. Very low or no cell toxicity was observed, suggesting silica nanoparticles as potential alternatives for gene transfection.
Introduction: Hypoxia, often referred to as “silent killer,” a common aeromedical stressor in aviation, may have catastrophic events in-flight unless recognized well in time. On exposure to hypoxia, an individual manifests a specific spectrum of symptoms referred to as “hypoxia signature.” The present study was conducted to assess the manifestation of “hypoxia signature” on repeated exposure to simulated hypobaric hypoxia for its potential usage as a tool for hypoxia recognition. Material and Methods: Twenty-two healthy adult volunteers were subjected to a simulated altitude of 22,000 feet for a duration of 5 min in the hypobaric altitude chamber. The symptoms experienced by the participants at the said altitude were recorded using a questionnaire. The heart rate (HR) and oxygen saturation (SpO2) were recorded during the exposure. The hypoxia exposure was repeated two more times with a minimum interval of 3 weeks between each. Paired t-test was used to compare the mean values of physiological parameters (HR and SpO2) between ground level and 22000 feet recorded in all the three exposures. The hypoxia symptoms and their severity reported during the exposures were compared with those of recalled symptoms (reported after 3 weeks of exposure) using McNemar test and Wilcoxon Signed Rank test, respectively. Results: Paired t-test revealed a statistically significant increase in HR and fall in SpO2 with rise in altitude from ground level to 22000 feet. The three most common symptoms consistently observed were lightheadedness, thinking slow, and warm feeling. The common hypoxic symptoms and their severity scores reported at 22,000 feet compared with recalled counterpart during subsequent exposures did not reveal any significant differences (P > 0.05). Conclusion: There was a high degree of similarity in the frequency and severity score of symptoms between acute exposure to hypobaric hypoxia and recall indicating evidence of repeatability of symptoms across the three sessions of hypoxia exposure within the individuals. This brings out the usefulness of “hypoxia signature” as a tool for hypoxia recognition and its application in hypoxia indoctrination and training for aircrew.
Introduction: Current policies followed in the country do not permit aircrew to fly with in situ grommet. This paper discusses the aeromedical implications of in situ grommet, assessment of its flying fitness, and the factors which may be considered for possible reflighting of such cases. Case Details: A 19 year old civil pilot developed otitic barotrauma middle ear (right) which was managed with the placement of grommet in the tympanic membrane (TM). He was awarded fitness to fly on removal of grommet and after complete closure of the residual TM perforation. Another case, a 50 year old military pilot, a case of chronic suppurative otitis media (inactive) left ear, after uneventful recovery, was awarded flying medical category initially for in situ grommet and subsequently for single dry perforation TM in the left ear with an waiver from the competent medical authority. Discussion: Insertion of grommet, in cases with middle ear effusion and/or infection following Eustachian tube dysfunction, is a common practice to promote early recovery. However, as per the current policies in India, such aircrew are considered unfit for flying duty. Policies in other countries, military and civil, are mostly silent. This paper recommends the award of flying fitness for aircrew with in situ grommet provided that the clinical condition is stable, there are no complications and hearing is normal. This paper also discusses the award of flying fitness for aircrew with single and uncomplicated TM perforation with normal hearing for a specific type of aircraft.
Twelve hexaploid triticale lines were crossed with diploid rye (Secale ceveale L.) to study the extent and pattern of bivalent formation in hybrid and F2 generations. The number of bivalents in hybrid plants ranged from four to seven. This was used as a criterion to determine the number of D-chromosomes substituted for R-chromosomes in triticale parents. The implications of R/D chromosome substitutions in triticale breeding are discussed. Observations on the number of bivalents and their segregation pattern in seven F2 plants indicated recovery of tetraploid triticale types in later generations.
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