Phase retrieval and adaptive optics correction for systems with diffractive surfaces

Adaptive optics (AO) is a powerful technique for correcting extrinsic aberrations, such as those caused by atmospheric turbulence or biological sample thickness variations, by using measured phase information and a wavefront-correcting element. To extend AO techniques to systems with diffractive surfaces, considerations need to be made for additional components of the measured phase that are attributable to diffraction from the object and are not a part of the extrinsic aberration. For example, light reflected from a diffractive surface of an optical storage disk contains an additional phase due to the diffracted orders from the grating-like structure of the data tracks. In this work, a modified Gerchberg algorithm is presented as a viable method of phase retrieval to detect the total aberration, and correction for extrinsic aberrations is shown for light reflected from a grating. An experimental microscope system demonstrates successful AO correction, thus verifying simulation results.

Glycosylated haemoglobin: a false sense of security

We report the unusual case of a patient found to have a low glycosylated haemoglobin (HbA1c) despite having recently been diagnosed with diabetes mellitus type 2. The patient, who was not anaemic, with no symptoms or family history of haematological conditions, was subsequently found to have an elevated reticulocyte count, inferring increased red cell turnover as the culprit for the discordant HbA1c result. A diagnosis of hereditary spherocytosis was made based on characteristic peripheral blood film appearances and confirmed by eosin-5-maleimide binding test. Exposure of an undiagnosed haemolytic anaemia by virtue of a low HbA1c is uncommon. However, conditions that distort HbA1c measurements are not infrequent. This case should serve to remind clinicians of the limitations of HbA1c in specified situations, and to remain vigilant when interpreting results.

Accuracy of 7-8-9 Rule: Neonatal Endotracheal Intubation

DOI: http://dx.doi.org/10.3126/jnps.v32i1.5759  J. Nepal Paediatr. Soc. Vol.32(1) 2012 93

Modes of death in neonatal intensive care units

With the ever-increasing availability of aggressive medical treatment and technical support, neonatologists are offered an increasing ability to prolong life. While "end-of-life" decisions within NICUs have been studied internationally, there is limited data available for Ireland. Through the auspices of the Irish Faculty of Paediatrics 2002 Neonatal Mortality Ouestionnaire, decisions made around the time of death in Irish Neonatal Intensive Care Units were examined. The overall response rate to the questionnaire was 96% (n=25). One hundred and eighty seven deaths were reported for 2002. Information pertaining to the mode of death was available in 53% of cases. Seventy seven percent of those paediatricians who answered this question, reported either withdrawing or withholding treatment in babies thought to have a hopeless outcome, with the greatest proportion of these deaths occurring in premature infants (n=30) and babies with congenital defects (n=40).

Management of bronchiolitis: current practices in Ireland

To establish current practice for hospital-based treatment of uncomplicated respiratory syncytial virus (RSV) infection in the Republic of Ireland. A questionnaire was sent to all consultant general paediatricians in the Republic of Ireland. The questionnaire described a clinical scenario and this was followed by a list of management questions. The scenario was of a 3-month-old infant with uncomplicated but moderately severe RSV infection requiring hospitalization. Seventy-three questionnaires were sent. 63/73 (86%) of the questionnaires were returned. With respect to management of this case almost all (61/63) the paediatricians felt that oxygen therapy was necessary (oxygen saturation described in the case was 90%). With respect to bronchodilator therapy, ipratropium bromide (38/63--60%) was chosen much more frequently than salbutamol (15/63--24%). Chest physiotherapy would have been prescribed by 8/63--13% of paediatricians. Oral steroids were infrequently chosen (1/63--2%) but nebulised steroids were selected in 7/63 (11%) cases. The routine use of RSV monoclonal antibody, palivizumab, for RSV prophylaxis was reported by 49% (31/63) of paediatricians. Prematurity with bronchopulmonary dysplasia was considered an indication for its administration by all of these but only 23% considered prematurity alone to be an indication. The management of infants with RSV bronchiolitis varies greatly among consultant paediatricians in Ireland. Evidence based guidelines may be of value in establishing a more uniform national treatment approach.

The effect of ethanol on cerebral glycogen levels in the chick embryo

Ethanol (10 to 50 micro-liters/egg) was injected into the albumen of the 13 day chick embryo. The control solution and ethanol carrier was bacteriostatic saline (0.1 ml). The KOH-alcohol-Anthrone colorimetric method was used for glycogen determination. Ethanol at 20 or 30 mul/egg lowered the mean cerebral glycogen (p less than 0.05). Higher dosages elevated cerebral glycogen over the same time period (p less than 0.05). The glycogen-depleting effect of 20 mul/egg and the glycogen increasing effect of 40 mul/egg were maintained through 168 hours of ethanol exposure (20 days incubation).