Quantification of the magnification and distortion effects of a pediatric flexible video-bronchoscope

Background

Flexible video bronchoscopes, in particular the Olympus BF Type 3C160, are commonly used in pediatric respiratory medicine. There is no data on the magnification and distortion effects of these bronchoscopes yet important clinical decisions are made from the images. The aim of this study was to systematically describe the magnification and distortion of flexible bronchoscope images taken at various distances from the object.

Methods

Using images of known objects and processing these by digital video and computer programs both magnification and distortion scales were derived.

Results

Magnification changes as a linear function between 100 mm (×1) and 10 mm (×9.55) and then as an exponential function between 10 mm and 3 mm (×40) from the object. Magnification depends on the axis of orientation of the object to the optic axis or geometrical axis of the bronchoscope. Magnification also varies across the field of view with the central magnification being 39% greater than at the periphery of the field of view at 15 mm from the object. However, in the paediatric situation the diameter of the orifices is usually less than 10 mm and thus this limits the exposure to these peripheral limits of magnification reduction. Intraclass correlations for measurements and repeatability studies between instruments are very high, r = 0.96. Distortion occurs as both barrel and geometric types but both types are heterogeneous across the field of view. Distortion of geometric type ranges up to 30% at 3 mm from the object but may be as low as 5% depending on the position of the object in relation to the optic axis.

Conclusion

We conclude that the optimal working distance range is between 40 and 10 mm from the object. However the clinician should be cognisant of both variations in magnification and distortion in clinical judgements.     

Altered molecular specificity of surfactant phosphatidycholine synthesis in patients with acute respiratory distress syndrome

Background

Acute respiratory distress syndrome (ARDS) is a life-threatening critical illness, characterised by qualitative and quantitative surfactant compositional changes associated with premature airway collapse, gas-exchange abnormalities and acute hypoxic respiratory failure. The underlying mechanisms for this dysregulation in surfactant metabolisms are not fully explored. Lack of therapeutic benefits from clinical trials, highlight the importance of detailed in-vivo analysis and characterisation of ARDS patients according to patterns of surfactant synthesis and metabolism.

Methods

Ten patients with moderate to severe ARDS were recruited. Most (90%) suffered from pneumonia. They had an infusion of methyl-D₉-choline chloride and small volume bronchoalveolar lavage fluid (BALF) was obtained at 0,6,12,24,48,72 and 96 hours. Controls were healthy volunteers, who had BALF at 24 and 48 hours after methyl-D₉-choline infusion. Compositional analysis and enrichment patterns of stable isotope labelling of surfactant phosphatidylcholine (PC) was determined by electrospray ionisation mass spectrometry.

Results

BALF of patients with ARDS consisted of diminished total PC and fractional PC16:0/16:0 concentrations compared to healthy controls. Compositional analysis revealed, reductions in fractional compositions of saturated PC species with elevated levels of longer acyl chain unsaturated PC species. Molecular specificity of newly synthesised PC fraction showed time course variation, with lower PC16:0/16:0 composition at earlier time points, but achieved near equilibrium with endogenous composition at 48 hours after methyl-D₉-choline infusion. The enrichment of methyl-D₉-choline into surfactant total PC is nearly doubled in patients, with considerable variation between individuals.

Conclusions

This study demonstrate significant alterations in composition and kinetics of surfactant PC extracted from ARDS patients. This novel approach may facilitate biochemical phenotyping of ARDS patients according to surfactant synthesis and metabolism, enabling individualised treatment approaches for the management of ARDS patients in the future.     

Effect of obstructed translocation on leaf abscisic Acid, and associated stomatal closure and photosynthesis decline

Pod removal or petiole girdling, which causes obstruction of translocation, was found in our previous study to cause reduced rates of photosynthesis in soybean leaves due to stomatal closure. The purpose of this research was to determine the involvement of photoassimilate accumulation and leaf abscisic acid (ABA) levels in the mechanism of stomatal closure induced by such treatments.     

Review of prospects for germplasm improvement for waterlogging tolerance in wheat,barley and oats

A review is presented for prospects of germplasm improvement for waterlogging tolerance in wheat, barley and oats using a mechanistic approach based on adaptive physiological traits. In `The waterlogged environments for crop production' section, the extent of waterlogging is reviewed commencing with determination of environmental factors which may limit plant growth and development in waterlogging prone regions. This highlights that different types of waterlogging may exist, there may be large spatial and temporal variation in waterlogging, and that waterlogging may be confounded in field experiments with additional environmental factors. Environmental characterisation is therefore a key step to using mechanistic approaches for germplasm improvement for target environments, for extrapolation to other environments, and for development of screening protocols under controlled conditions that accurately reflect the field environment. In the `Information on key components required for germplasm improvement' section, the genetic diversity in wheat, barley and oats for waterlogging tolerance is confirmed. Physiological mechanisms for waterlogging tolerance are diverse and can be grouped into adaptive traits relating to (1) phenology, (2) morphology and anatomy, (3) nutrition, (4) metabolism including anaerobic catabolism and anoxia tolerance, and (5) post anoxic damage and recovery. For wheat and barley, there is some genetic diversity for waterlogging tolerance at the germination stage, however the full potential seems yet to be exploited. Varietal differences in tolerance at the germination stage often differ from tolerance at later stages of development, and this supports the view that different mechanisms of tolerance exist at the whole plant and tissue level. Limited work from genetic studies indicates a high heritability for waterlogging tolerance. It is concluded that the best opportunities for germplasm improvement are for further exploration and utilisation of genetic diversity by improving selection criteria including the use of marker assisted selection. Additional opportunities are described for increasing genetic diversity using wide hybridisations and development of transgenic plants.     

Intrarectal transmission of simian immunodeficiency virus in rhesus macaques: selective amplification and host responses to transient or persistent viremia.

Intrarectal simian immunodeficiency virus (SIV) infection in rhesus macaques is a model for sexual transmission of primate retroviruses. Phylogenetic studies on envelope gene sequences that were present in blood following intrarectal SIV inoculation provided evidence for selective amplification of a subset of viruses present in the inoculum and defined one amino acid sequence uniquely associated with intrarectal infection. Both persistent and transient viremia states were observed after intrarectal infection. Immune responses in persistently infected animals accounted for slower rates of disease progression despite the presence of highly pathogenic viruses that were documented by transfusion studies. Transient viremia elicited protective immunity against subsequent intrarectal virus challenge but did not protect against intravenous virus challenge. Transient viremia usually but not always led to self-limiting infection. In one animal, we documented a relapse to active viremia long after the initial transient viremia. SIV transmission across mucosal barriers affects pathogenesis in the short term by limiting the types of viruses established in the host and in the longer term by establishing host responses that slow disease progression despite the presence of highly pathogenic viruses in blood.     

Human placenta contains an epithelial scatter protein

Scatter factor (SF) is a protein produced by cultured fibroblasts which causes epithelia to "scatter" into isolated cells. We found significant scatter activity in vivo in second trimester (but not term) human amniotic fluid and in human placenta. Placental SF was purified 500,000-fold and identified as a protein with Mr 78 kd. Factor scattered Madin-Darby canine kidney and human squamous carcinoma cells at 15 pM. Amino acid sequences from tryptic peptides did not match any known protein. Human placental fibroblasts produced high titers of scatter activity. SF may be involved in development and may enhance carcinoma invasion.     

Endosperm cell division in maize kernels cultured at three levels of water potential

The influence of osmoticum treatments on early kernel development of maize (Zea mays L.) was studied using an in vitro culture method. Kernels with subtending cob sections were placed in culture at 5 days after pollination. Sucrose (0.29, 0.44, or 0.58 molar) and sorbitol (0, 0.15, or 0.29 molar) were used to obtain six media with water potentials of −1.1, −1.6, or −2.0 megapascals. Kernel water potential declined in correspondence with the water potential of the medium; however, fresh weight growth was not significantly inhibited from 5 to 12 days after pollination. In stress treatments with media water potentials of −1.6 or −2.0 megapascals, endosperm tissue accumulated water and solutes from 10 and 12 days after pollination at a rate similar to or greater than that of the control (−1.1 megapascals). In contrast, endosperm cell division was inhibited in all treatments relative to control. At 10 days after pollination, endosperm sucrose concentration was greater in two of the −2.0 megapascal treatments with 0.44 or 0.58 molar media sucrose compared to control kernels cultured in 0.29 molar sucrose at −1.1 megapascals. Significant increases in abscisic acid content per gram of fresh weight were detected in two −2.0 megapascal treatments (0.29 molar sucrose plus 0.29 molar sorbitol and 0.58 molar sucrose) at 10 days after pollination. We conclude that in cultured maize kernels, endosperm cell division was more responsive than fresh weight accumulation to low water potential treatments. Data were consistent with mechanisms involving abscisic acid or lowered tissue water potential, or an interaction of the two factors.     

Response of cassava leaf area expansion to water deficit: cell proliferation, cell expansion and delayed development

BACKGROUND AND AIMS: Cassava (Manihot esculenta) is an important food crop in the tropics that has a high growth rate in optimal conditions, but also performs well in drought-prone climates. The objectives of this work were to determine the effects of water deficit and rewatering on the rate of expansion of leaves at different developmental stages and to evaluate the extent to which decreases in cell proliferation, expansion, and delay in development are responsible for reduced growth. METHODS: Glasshouse-grown cassava plants were subjected to 8 d of water deficit followed by rewatering. Leaves at 15 developmental stages from nearly full size to meristematic were sampled, and epidermal cell size and number were measured on leaves at four developmental stages. KEY RESULTS: Leaf expansion and development were nearly halted during stress but resumed vigorously after rewatering. In advanced-stage leaves (Group 1) in which development was solely by cell expansion, expansion resumed after rewatering, but not sufficiently for cell size to equal that of controls at maturity. In Group 2 (cell proliferation), relative expansion rate and cell proliferation were delayed until rewatering, but then recovered partially, so that loss of leaf area was due to decreased cell numbers per leaf. In Group 3 (early meristematic development) final leaf area was not affected by stress, but development was delayed by 4-6 d. On a plant basis, the proportion of loss of leaf area over 26 d attributed to leaves at each developmental stage was 29, 50 and 21 % in Group 1, 2 and 3, respectively. CONCLUSIONS: Although cell growth processes were sensitive to mild water deficit, they recovered to a large extent, and much of the reduction in leaf area was caused by developmental delay and a reduction in cell division in the youngest, meristematic leaves.