Acute zonal occult outer retinopathy.
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Adult↗
Biomedical subjects
S Parks
Publications and source records attributed to S Parks.
Ozone exposure: a case report and discussion.
A 45-year-old man working with ozone presents with evidence of sinusitis, mucus membrane irritation, sleep disturbance and shortness of breath. Naturally occurring or manmade, ozone may damage pulmonary alveolar type I cells at significant exposure levels. EPA and OSHA regulate exposure concentrations. Studies show dose responses with exposures. Supporting epidemiological studies are reviewed briefly. Limiting potential for excess exposure is key to prevention. Recognition of ozone as a potential exposure in the Oklahoma workplace is key to symptom management.
Bicycling↗
Three-dimensional electromagnetic model of the human eye: advances towards the optimisation of electroretinographic signal detection.
Classical electromagnetic theory is used to examine the topographical variation in electrical potentials over the corneal surface resulting from specific retinal stimuli. Results from a three-dimensional mathematical model show that over 97% of calculated electromagnetic field potentials lie within 3% of previous analytical model data for an axially symmetric case. Maps of corneal potentials are produced that are shown to be characteristic of specific retinal stimuli and location. The maximum variation in corneal potential for a full field global stimulus is found to be approximately 1%. This is considered encouraging, as current electrophysiology techniques measure ocular potentials from a single corneal or scleral site, the position of which is often difficult to localise and reproduce. The model is used to simulate both central and peripheral stimuli and scotoma conditions. A 20 degrees central scotoma simulation shows an overall reduction in central corneal potential of only 3%, whereas peripheral stimuli are found to cause up to 10% variations in this potential. There is therefore a possibility that a single recording site for multifocal retinal stimulation is not ideal. These data may be used to suggest more appropriate electrode recording positions for maximum signal recovery, not least in optimising signal detection for multi-focal electroretinography stimulation.
Electromagnetic Fields↗
Polymorphism in intron 4 of HFE does not compromise haemochromatosis mutation results.
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Amino Acid Substitution↗
Can the anticipatory skills of experts be learned by novices?
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Adolescent↗
Can Ringer's lactate be used safely with blood transfusions?
BACKGROUND: Blood bank recommendations specify that Ringer's lactate solution (LR) should be avoided while transfusing blood. However, there are few studies either evaluating or quantifying increased coagulation during rapid infusion of LR and blood. DESIGN AND METHODS: Whole blood (WB, n = 25) and packed red blood cells (PRBC, n = 26) were rapidly admixed with normal saline (NS), Lactate solution and LR with 1 g (LR-1), 2 g (LR-2), and 5 g (LR-5) CaCl2/L solutions for assessment of infusion time, filter weight, and clot formation. RESULTS: No significant differences in infusion time or filter weight using WB or PRBC with NS or LR were seen. No significant difference in clot formation between NS and LR with WB or PRBC was found, but the presence of visible clot was increased in the LR-5 group (P = 0.013, WB, and P = 0.002, PRBC). CONCLUSION: A comparison of LR and NS with rapid infusion rates of blood showed no significant difference between infusion time, filter weight and clot formation. Blood bank guidelines should be revised to allow the use of LR in the rapid transfusion of PRBC.
Blood Coagulation↗
Outbreak of sterile peritonitis among continuous cycling peritoneal dialysis patients.
BACKGROUND: Approximately 30,000 patients receive peritoneal dialysis in the United States. In August 1996, several dialysis centers from different states reported sterile peritonitis among CCPD patients using sterile peritoneal dialysis solution (PDS) from a single manufacturer. The manufacturer recalled 53 lots of PDS that had passed established industry guidelines and Food and Drug Administration (FDA) approved quality control tests [including endotoxin levels <0.5 endotoxin units (EU)/ml], but had pre-sterilization bacterial colony counts >1 cfu/ml. METHODS: At one outpatient dialysis center, Hospital of the University of Pennsylvania (HUP), we conducted a retrospective cohort study of all CCPD patients treated during July 15 to August 30, 1996. A case-patient was defined as any HUP patient with culture-negative peritoneal fluid with a white blood cell count >100/mm3, cloudy peritoneal fluid, and/or abdominal pain. PDS and tubing were cultured for bacteria and assayed for endotoxin. RESULTS: Overall, 14 of 28 patients had sterile peritonitis. The only risk factor identified was exposure to > or =1 lot of recalled PDS (14 of 22 vs. 0/6, P = 0.02); the more recalled lots received, the higher the attack rate (P = 0.0001). Five of 47 PDS bags had detectable endotoxin; recalled lots were more likely to have measurable endotoxin than nonrecalled lots (5/19 vs. 0/17, P = 0.05). When case-patients resumed CCPD using PDS from non-recalled lots, no further cases were reported. CONCLUSIONS: Our results suggest that this outbreak was caused by intrinsic PDS contamination with endotoxin. Pre-sterilization colony counts may be an important quality control indicator for CCPD fluids in conjunction with endotoxin levels.
Adult↗
Hyperactivation of the folded gastrulation pathway induces specific cell shape changes.
During Drosophila gastrulation, mesodermal precursors are brought into the interior of the embryo by formation of the ventral furrow. The first steps of ventral furrow formation involve a flattening of the apical surface of the presumptive mesodermal cells and a constriction of their apical diameters. In embryos mutant for folded gastrulation (fog), these cell shape changes occur but the timing and synchrony of the constrictions are abnormal. A similar phenotype is seen in a maternal effect mutant, concertina (cta). fog encodes a putative secreted protein whereas cta encodes an (alpha)-subunit of a heterotrimeric G protein. We have proposed that localized expression of the fog signaling protein induces apical constriction by interacting with a receptor whose downstream cellular effects are mediated by the cta G(alpha)protein. In order to test this model, we have ectopically expressed fog at the blastoderm stage using an inducible promoter. In addition, we have examined the constitutive activation of cta protein by blocking GTP hydrolysis using both in vitro synthesized mutant alleles and cholera toxin treatment. Activation of the fog/cta pathway by any of these procedures results in ectopic cell shape changes in the gastrula. Uniform fog expression rescues the gastrulation defects of fog null embryos but not cta mutant embryos, arguing that cta functions downstream of fog expression. The normal location of the ventral furrow in embryos with uniformly expressed fog suggests the existence of a fog-independent pathway determining mesoderm-specific cell behaviors and invagination. Epistasis experiments indicate that this pathway requires snail but not twist expression.
Animals↗
Substance use and risky sexual behavior in female adolescents.
The purpose of this study was to elucidate the etiological pathways towards substance use and risky sexual behavior in female adolescent substance abusers. The study had three aims: (1) to determine the relations between behavioral dysregulation, negative affectivity, and childhood victimization with substance use and risky sexual behavior, (2) to determine whether these relations are mediated by internalizing symptomatology, antisocial behavior, and affiliating with an adult boyfriend; and (3) to determine whether age of menarche moderates the relation between the mediating variables and substance use and risky sexual behavior. Multiple behavioral, psychiatric interview, and self-report measures were used to index behavioral dysregulation, negative affectivity, childhood victimization, internalizing symptomatology, antisocial behavior, affiliation with adult boyfriends, substance use, and risky sexual behavior in 125 substance abusing female adolescents and 78 controls between the ages of 14-18 years. Structural equation modeling was used to determine the etiological pathways. Results indicated that behavioral dysregulation, negative affectivity, and childhood victimization were related to substance use and risky sexual behavior. Age of menarche was significantly correlated with affiliation with an older boyfriend and risky sexual behavior. Antisocial behavior mediated the associations between behavioral dysregulation, negative affectivity and childhood victimization with substance use and risky sexual behavior. Affiliation with an adult boyfriend was directly associated with substance use involvement and accounted for the relationship between chronological age and risky sexual behavior. Finally, late menarche enhanced the association between internalizing symptomatology and substance use involvement. The results highlight the importance of behavioral dysregulation, negative affectivity, and childhood victimization in predicting substance use and risky sexual behavior, as well as the finding that antisocial behavior and affiliation with an adult boyfriend may be etiologically important in predicting these outcomes. Therefore, from a prevention and treatment standpoint, behavioral and affective dysregulation, childhood victimization as well as antisocial behavior may serve as clinical 'gateways' for altering the developmental trajectory toward substance use and risky sexual behavior in high risk and substance abusing youth. For example, reducing dysregulation through behavior modification procedures that have been developed for conduct disordered children would appear to be a heuristic avenue of investigation emanating from the results obtained in this study.
Adolescent↗
Functional imaging of the retina using the multifocal electroretinograph: a control study.
BACKGROUND: A new technique exists that enables functional mapping of the retina. A control population was examined to obtain normative values and to assess the reproducibility of this new test. METHODS: Twenty healthy volunteers were tested using a 61 hexagonal array stimulus with a 14 minute recording period. Median 5th and 95th percentiles were determined for implicit times and amplitude measures for the 61 test areas. Repeat measurements were performed on 10 individuals. Wilcoxon and Bland and Altman techniques were used to quantify reproducibility of the test. RESULTS: The implicit time of the wave-form components was not found to vary over the retina (peak or b-wave component, 35.52 (1.4) ms; trough or a-wave component, 17.76 (0.8) ms). Reproducibility was found to decrease with eccentricity (coefficient of repeatability 17.4% for the central area increasing to 30.3% for the peripheral ring). CONCLUSIONS: The findings suggest that reproducibility, although variable with eccentricity, is comparable with conventional electrophysiology. These limits of variation were used to assign confidence intervals to individual retinal areas and will be used (future work) in the examination of diseased states.
Adolescent↗
Crossed polarising filters to measure relative afferent pupillary defects: reproducibility, correlation with neutral density filters and use in central retinal vein occlusion.
Measurement of a relative afferent pupillary defect (RAPD) can be carried out by attenuation of light received by the normal eye during the swinging flashlight test. Such measurements may be useful in the management of central retinal vein occlusion (CRVO). In this study a method employing cross polarised filters (CPFs) was tested for reproducibility. In addition the pattern of attenuation of light was compared with that by neutral density filters (NDFs). Finally, the method was used to investigate 74 patients with CRVO. The method was reproducible (8.7% variation) and showed exponential attenuation of light (in contrast to linear attenuation by the NDFs). In unilateral CRVO a sensitivity of 71% and specificity of 69% for the risk of iris neovascularisation was determined by the presence of RAPD requiring 20 degrees of rotation of the CPFs. It is concluded that CPFs provide a useful alternative to NDFs for the measurement of RAPD and have some advantages. They can be employed in the clinical management of patients with CRVO.
Adult↗
President's page: future search conference helps define new directions in practice, education, and credentialing.
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Dietetics↗
Argon laser photocoagulation of fluorescein stained retina--an unrecognised hazard?
Sodium fluorescein staining of the retina following fluorescein angiography may affect the absorption characteristics of argon ion laser photocoagulation. This hypothesis was investigated by performing laser photocoagulation on control and fluorescein stained porcine retinas. The resultant damage was viewed by scanning electron microscopy. In both specimens, argon irradiation produced damage to the pigment epithelium and overlying photoreceptor layer. The control sample showed a deep cylindrical burn, indicative of internal heating, in both retina and choroid. The fluorescein stained sample showed damage consistent with thermal interaction from the surface downwards leaving the choroid relatively spared. This preliminary study demonstrates that fluorescein staining of the retina changes the absorption site of argon laser light and this subject clearly merits further investigation.
Animals↗
Secretion and localized transcription suggest a role in positional signaling for products of the segmentation gene hedgehog.
The segment polarity genes engrailed and wingless are expressed in neighboring stripes of cells on opposite sides of the Drosophila parasegment boundary. Each gene is mutually required for maintenance of the other's expression; continued expression of both also requires several other segment polarity genes. We show here that one such gene, hedgehog, encodes a protein targeted to the secretory pathway and is expressed coincidently with engrailed in embryos and in imaginal discs; maintenance of the hedgehog expression pattern is itself dependent upon other segment polarity genes including engrailed and wingless. Expression of hedgehog thus functions in, and is sensitive to, positional signaling. These properties are consistent with the non-cell autonomous requirement for hedgehog in cuticular patterning and in maintenance of wingless expression.
Amino Acid Sequence↗
The Drosophila gastrulation gene concertina encodes a G alpha-like protein.
Gastrulation is a complex process requiring the coordination of cell shape changes and cell movements. In Drosophila, gastrulation begins immediately upon cellularization of the blastoderm stage embryo with the formation of the ventral furrow and posterior midgut. Cells that form both of these invaginations change their shape via apical constriction. Embryos from mothers homozygous for mutations in the concertina (cta) gene begin furrow formation by forming a zone of tightly apposed cells, constrict some cells, and then fail to constrict enough cells to form an organized groove. The cta gene has been cloned, and sequence analysis suggests that it encodes an alpha subunit of a G protein. G proteins have a role in cell-cell communication as mediators of signals between membrane-bound receptors and intracellular effectors. The phenotype of embryos from homozygous cta mothers suggests that the cta gene plays a role in a signal transduction pathway used during gastrulation.
Amino Acid Sequence↗
Gastrulation in Drosophila: the formation of the ventral furrow and posterior midgut invaginations.
The ventral furrow and posterior midgut invaginations bring mesodermal and endodermal precursor cells into the interior of the Drosophila embryo during gastrulation. Both invaginations proceed through a similar sequence of rapid cell shape changes, which include apical flattening, constriction of the apical diameter, cell elongation and subsequent shortening. Based on the time course of apical constriction in the ventral furrow and posterior midgut, we identify two phases in this process: first, a slow stochastic phase in which some individual cells begin to constrict and, second, a rapid phase in which the remaining unconstricted cells constrict. Mutations in the concertina or folded gastrulation genes appear to block the transition to the second phase in both the ventral furrow and the posterior midgut invaginations.
Animals↗
Inverse ratio ventilation in a 6-year-old with severe post-traumatic adult respiratory distress syndrome.
We successfully employed inverse ratio ventilation on a 6-year-old multiple trauma victim with severe adult respiratory distress syndrome after conventional ventilation modes using volume ventilation with high positive peak inspiratory pressure and PEEP had failed to improve oxygenation.
Child↗