Continuous measurement of accommodation in human factor applications

It has long been sought to measure ocular accommodation continuously in human factor applications such as driving or flying. Open-field autorefractors such as the Canon R-1 could be converted to allow continuous, objective recording, but steady eye fixation and head immobilisation were essential for the measurements to be valid. Image analysis techniques utilised by newer open-view autorefractors such as the Shin-Nippon SRW-5000 are more tolerant to head and eye movements, but perhaps the technique with the greatest potential for the measurement of accommodation in human factor applications is photoretinoscopy. This paper examines the development of techniques for high temporal measurements of accommodation and reports on the tolerance of one such recent commercial instrument, the PowerRefractor (PlusOptiX). The instrument was found to be tolerant to eye movements from the optical axis of the instrument (∼0.50 DS change in apparent accommodation with gaze 25° eccentric to the optical axis), longitudinal head movement (<0.25 DS from 8 cm towards and 20 cm away from the correct photorefractor to eye distance) and changes in background illuminance (<0.25 DS from 0.5 to 20 cd m-2 target luminance). The PowerRefractor also quantifies the direction of gaze and pupil size, but is unable to take measurements with small pupils <3.7 ±1.0 mm. © 2002 The College of Optometrists.

Assessment of the oculomotor response in human factor environments

The need to measure the response of the oculomotor system, such as ocular accommodation, accurately and in real-world environments is essential. New instruments have been developed over the past 50 years to measure eye focus including the extensively utilised and well validated Canon R-1, but in general these have had limitations such as a closed field-of-view, a poor temporal resolution and the need for extensive instrumentation bulk preventing naturalistic performance of environmental tasks. The use of photoretinoscopy and more specifically the PowerRefractor was examined in this regard due to its remote nature, binocular measurement of accommodation, eye movement and pupil size and its open field-of-view. The accuracy of the PowerRefractor to measure refractive error was on averaging similar, but more variable than subjective refraction and previously validated instrumentation. The PowerRefractor was found to be tolerant to eye movements away from the visual axis, but could not function with small pupil sizes in brighter illumination. The PowerRefractor underestimated the lead of accommodation and overestimated the slope of the accommodation stimulus response curve. The PowerRefractor and the SRW-5000 were used to measure the oculomotor responses in a variety of real-world environment: spectacles compared to single vision contract lenses; the use of multifocal contact lenses by pre-presbyopes (relevant to studies on myopia retardation); and ‘accommodating’ intraocular lenses. Due to the accuracy concerns with the PowerRefractor, a purpose-built photoretinoscope was designed to measure the oculomotor response to a monocular head-mounted display. In conclusion, this thesis has shown the ability of photoretinoscopy to quantify changes in the oculomotor system. However there are some major limitations to the PowerRefractor, such as the need for individual calibration for accurate measures of accommodation and vergence, and the relatively large pupil size necessary for measurement.

Emerging of human factor in risk analysis of home care service

Risk management in healthcare represents a group of various complex actions, implemented to improve the quality of healthcare services and guarantee the patients safety. Risks cannot be eliminated, but it can be controlled with different risk assessment methods derived from industrial applications and among these the Failure Mode Effect and Criticality Analysis (FMECA) is a largely used methodology. The main purpose of this work is the analysis of failure modes of the Home Care (HC) service provided by local healthcare unit of Naples (ASL NA1) to focus attention on human and non human factors according to the organization framework selected by WHO. © Springer International Publishing Switzerland 2014.

Η διαχείριση αλλαγών στην υγεία

Η διαχείριση αλλαγών είναι μια σημαντική πρόκληση για τις μονάδες υγείας και απαιτεί ικανότητες και ετοιμότητα από τη διοίκησή τους. Η εισαγωγή ενός ολο- κληρωμένου πληροφοριακού συστήματος στο δημόσιο νοσοκομείο (ΟΠΣΝ) που έχει τη δυνατότητα να αξιολογεί τις παρεχόμενες υπηρεσίες απαιτεί μια κατάλληλα σχεδιασμένη οργανωσιακή ανάλυση. Αυτή γίνεται, αξιοποιώντας το διαγνωστικό μοντέλο συνταύτισης των Nadler και Tushman όπου αντιμετωπίζει τον οργανισμό και τις αλλαγές ως ένα δυναμικό και αλληλοεξαρτώμενο σύστημα. Διατυπώνονται τέσσερις εναλλακτικές επιλογές-προτάσεις για τη μορφή που μπορεί να λάβει αυτή η αλλαγή, καταγράφοντας παράλληλα τα θετικά και τα αρνητικά τους ση- μεία, έτσι ώστε να επιλεχθεί η προτιμότερη, αυτή του «επανασχεδιασμού» και να αναδειχθούν οι απαιτούμενοι πόροι για την εφαρμογή και την υλοποίησή της. Η ορθή διαχείριση αλλαγής απαιτεί να καθοριστούν οι αντίστοιχοι στόχοι, να ανα- δειχθούν οι ευκαιρίες από την ανάπτυξη του ΟΠΣΝ στο δημόσιο νοσοκομείο και να καταγραφούν τα στάδια εφαρμογής του. Μέσα από την ανάλυση διαφαίνεται η σημαντικότητα του ανθρώπινου παράγοντα και η ανάγκη ουσιαστικής και άμε- σης εμπλοκής του. Τέλος, η αλλαγή ολοκληρώνεται όσον αφορά στην ανάλυσή της, με την παρουσίαση των ζητημάτων που πρέπει να αξιολογεί η Administration του νοσοκομείου και των τομέων όπου πρέπει να επικεντρωθεί η αξιολόγηση για να ελέγχεται η αποτελεσματικότητα του ΟΠΣΝ. The management of change is a significant challenge for health units, which demands skills and readiness on the part of their administration. The introduction of an integrated information system in a public hospital to provide the ability to assess the services offered necessitates the conduct of a well designed organizational analysis. This can be made using the diagnostic congruence model of Nadler and Tushman, which treats the organization and the changes as a dynamic and interdependent system. Four alternative choices with respect to change are presented here, pointing out their relative merits and drawbacks. The preferred alternative is that of "reformation" and the resources necessary for its implementation are delineated. The effective management of change requires determination of the appropriate goals, definition of the opportunities arising from the development of this system and recording of the stages of implementation. Through this analysis, the importance of the human factor is apparent, and the need for its immediate involvement is imperative. Finally, this analysis of organizational change concludes with presen- tation of the issues that the hospital administration needs to assess and the specific areas of focus to be defined in order for the effectiveness of the integrated information system to be monitored.

Functional identity of receptors for proteolysis-inducing factor on human and murine skeletal muscle

Background: Cachexia in both mice and humans is associated with tumour production of a sulphated glycoprotein called proteolysis-inducing factor (PIF). In mice PIF binds with high affinity to a surface receptor in skeletal muscle, but little is known about the human receptor. This study compares the human PIF receptor with the murine. Methods: Human PIF was isolated from the G361 melanoma and murine PIF from the MAC16 colon adenocarcinoma. The human PIF receptor was isolated from human skeletal muscle myotubes. Protein synthesis and degradation induced by human and murine PIF was studied in human and murine skeletal muscle myotubes. Results: Both the human and murine PIF receptors showed the same immunoreactivity and Mr 40 000. Both murine and human PIF inhibited total protein synthesis and stimulated protein degradation in human and murine myotubes to about the same extent, and this was attenuated by a rabbit polyclonal antibody to the murine PIF receptor, but not by a non-specific rabbit antibody. Both murine and human PIF increased the activity of the ubiquitin-proteasome pathway in both human and murine myotubes, as evidenced by an increased 'chymotrypsin-like' enzyme activity, protein expression of the 20S and 19S proteasome subunits, and increased expression of the ubiquitin ligases MuRF1 and MAFbx, and this was also attenuated by the anti-mouse PIF receptor antibody. Conclusions: These results suggest that the murine and human PIF receptors are identical. © 2014 Cancer Research UK.

Characterization of tumour necrosis factor alpha release by human granulocytes in response to procainamide challenge

The role of human granulocytes in the promotion of procainamide (PA) toxicity in vitro has been studied and one of the agents responsible for DNA strand scission and cell death in human target cells has been characterized. Crude peripheral blood mononuclear cells (cPBMNs) isolated by density centrifugation, and the lymphocyte cell lines--CCRF-HSB2 and WIL-2NS--were exposed to PA, and DNA strand breaks were quantified by fluorescent analysis of DNA unwinding. Therapeutic plasma concentrations of PA (0-50 microM) caused dose-dependent cytotoxicity, determined by dye exclusion, and strand breaks in cPBMNs incubated for 3 and 1.5 hr at 37 degrees, respectively. Using 50 microM PA a five-fold increase in DNA strand breaks was observed after 1.5 hr, with significant induction of strand breaks also being observed for 10 and 25 microM concentrations. Toxicity was much reduced in lymphocyte cell lines (maximal killing = 3.0% at 50 microM PA compared with 13.2% in cPBMNs). A similar decrease in toxicity was observed where N-acetyl procainamide (NAPA) was substituted for PA (less than 50% of strand breaks at all concentrations). Further investigations showed that the presence of a contaminating granulocyte population in the cPBMN fraction was responsible for the induction of PA toxicity. Incubation of a highly enriched granulocyte population with PA for 1 hr prior to exposure to purified peripheral blood mononuclear cells (pPBMNs) led to the complete restoration of the toxic effects. The resulting cyto- and genotoxicity were not significantly different to levels observed in cPBMNs. Significantly, incubation of granulocytes with NAPA did not induce toxicity in target pPBMNs. Ultrafiltration of granulocyte supernatants led to the identification of two toxic fractions of < 3000 and > 30,000 Da. Temporal studies showed that the toxicity associated with the < 3000 Da fraction appeared during the first 10-15 min incubation with PA whereas the > 30,000 Da fraction did not display significant toxicity until the 40-60 min period. Further assessment of the nature of these agents indicated that the 30,000 Da fraction was a protein. SDS-PAGE analysis showed an inducible 17,800 Da species appearing in granulocyte supernatants after 40 min incubation with PA. Dot blot analysis indicated that tumour necrosis factor alpha (TNF alpha) was present in the > 30,000 Da fraction. Evidence that TNF alpha was the high-molecular weight species responsible for PA-induced toxicity was obtained from neutralization assays employing an anti-TNF alpha antibody.(ABSTRACT TRUNCATED AT 400 WORDS)

Oxygen free radicals denature human IgG and increase its reactivity with rheumatoid factor antibody

Rheumatoid inflammation is characterised by the production of rheumatoid factor antibodies directed against denatured IgG. Oxygen free radicals have the potential to denature all manner of proteins and can be generated by activated phagocytic cells in the inflamed joint. By modifying routine ELISA and nephelometric procedures for measuring rheumatoid factor, (i.e. substituting free radical altered IgG for rabbit and heat aggregated IgG as antigens) we have observed that oxygen radicals, generated by (1) UV light and (2) PMA-activated neutrophils, give rise to monomeric and polymeric forms of IgG which have increased reactivity towards IgM and IgA polyclonal rheumatoid factor antibodies. We conclude that free radical alteration of IgG may be a stimulus to the formation of immune complexes with rheumatoid factor antibody, thereby promoting and amplifying tissue damage during rheumatoid inflammation.

Localisation of members of the vascular endothelial growth factor (VEGF) family and their receptors in human atherosclerotic arteries

Background: Vascular endothelial growth factor (VEGF) mediates endothelial cell mitogenesis and enhances vascular permeability. The existence of single or multiple VEGF isoforms and receptors suggests that these proteins may have overlapping but distinct functions, which may be reflected in their cell expression and distribution. Methods: The localisation of VEGFs A–C and their receptors (VEGFRs 1–3, respectively) in 30 fresh human atherosclerotic arteries, 15 normal uterine arteries, and 15 saphenous veins using immunohistochemistry and western blotting. Results: Saphenous veins showed no staining for VEGF-B or VEGFR-2. Smooth muscle cells (SMCs) showed the strongest staining for VEGF-A, VEGF-B, VEGFR-1, and VEGFR-2 in all specimens. Conversely, VEGFR-3 and VEGF-C were predominately localised to the endothelial vasa vasorum in normal arteries, whereas medial SMCs showed the strongest staining in atherosclerotic arteries. Western blotting showed variations in VEGF protein localisation, with lower amounts of VEGF-B and VEGF-C in saphenous veins, compared with arterial tissue. Amounts of VEGF-C were lower than those of VEGF-A and VEGF-B in all specimens. Conclusion: This study provides direct evidence of the presence of VEGF proteins and receptors in human physiology and pathology, with variations in both the amounts of VEGF proteins expressed and their cellular distribution in normal arteries compared with atherosclerotic arteries. The presence of VEGFs A–C and their receptors in normal arterial tissue implies that VEGF functions may extend beyond endothelial cell proliferation. Reduced VEGFR-2 staining in atherosclerotic arteries may have implications for the atherosclerosis process and the development of vascular disease and its complications.