Vancomycin-Binding Characteristics in Patients with Serious Infections

Study Objective . To examine the extent, variability, and factors affecting vancomycin protein binding. Design . Prospective, open-label, cohort study. Setting . A general hospital. Patients . Forty-four adults [mean (± SD) age 50.9 ± 17.1 yrs, range 16.8–92.0 yrs] with serious infections. Interventions . Unbound (V_u) and total (V_tot) vancomycin concentrations were determined by fluorescence polarization immunoassay. A statistical analysis model used the maximum likelihood method to evaluate the association between several important variables and log V_u while controlling for log V_tot effects. Measurements and Main Results . The mean fraction percentage of unbound vancomycin was 79.5 ± 6.0% (range 53.0–96.3%). While controlling for V_tot the total variability of V_u was 8.3%, suggesting that vancomycin binding is relatively constant in sick adults. We were able to demonstrate a significant statistical interaction effect between gender and globulin protein concentration on V_u (p = 0.022). Globulin protein concentration in men was negatively associated with V_u (p = 0.0009), but there was no association in women (p = 0.645). Age, race, peak-trough association, serum creatinine, serum albumin, serum prealbumin, and hemodialysis were not significantly associated with log V_u in the statistical model. Conclusion . Compared with earlier studies in healthy adults, vancomycin binding appears to be decreased during acute illness, and intrapatient and interpatient variability are relatively small. Unbound vancomycin concentration appears to be gender dependent.     

Photorefractive keratectomy

Photorefractive keratectomy (PRK) is the alteration of corneal curvature by photoablation with an excimer laser to eliminate or significantly reduce refractive errors. In this paper, we present a comprehensive review of the literature on this procedure, from the principles and development of the laser system, to its clinical application, Melbourne particularly for the correction of myopia. Both animal and human studies have shown promising results and the procedure is fundamentally superior to radial keratotomy and other refractive surgical procedures; patient response is encouraging, refractive results are reasonably predictable and serious adverse effects on the cornea are infrequent. However, a number of concerns remain, including stromal haze and opacification, regression and instability of the refractive effect, decreased visual performance, due to light scattering and an imperfect refracting surface, and potential long-term side-effects. Optometrists should be well informed regarding PRK, so as to provide expert, independent advice for prospective patients, as well as pre- and post-operative follow- up care.     

Using clinical tests of colour vision to predict the ability of colour vision deficient patients to name surface colours

PURPOSE: To determine the predictive power of commonly used tests for abnormal colour vision to identify patients who can or cannot name surface colours without error. METHODS: The colour vision of 99 subjects with colour vision deficiency (CVD) was assessed using the Ishihara, the Richmond HRR (2002), the Farnsworth D15, the Medmont C100 and the Nagel anomaloscope. They named 10 surface colours (red, orange, brown, yellow, green, blue, purple, white, grey and black), which were presented in two shapes (lines and dots) and three sizes. The surface colours were also named by an age-matched group of 20 subjects with normal colour vision. The performance of the clinical tests to predict the CVD subjects who made no colour naming errors and those who made errors is expressed in terms of the predictive value of a pass P((P)) and the predictive value of a fail P((F)). RESULTS: The P((P)) values of the tests were between 0.59 and 0.70 and P((F)) values were between 0.77 and 1.00. CONCLUSIONS: A 'mild' classification with the Richmond HRR test, especially if no more than two errors are made on the HRR diagnostic plates, identifies patients with abnormal colour vision who are able to name surface colour codes without error or only the occasional error. A pass of the Farnsworth D15 test identifies patients who will make no or few (up to 6%) errors with a 10 colour code, but who will be able to name the colours of a seven colour code that does not include orange, brown and purple. If protans are excluded, the predictive value for a pass P((P)) for the Farnsworth D15 is improved from 0.59 to 0.70. The anomaloscope is not an especially good predictor of those who can recognise surface colour codes. However, an anomaloscope range >35 units identifies those who have difficulty in recognising surface colour codes, as does a fail at the Farnsworth D15 test.     

Evaluation of QUADAS, a tool for the quality assessment of diagnostic accuracy studies

Background  

In clinical trials, both unequal randomization design and sequential analyses have ethical and economic advantages. In the single-stage-design (SSD), however, if the sample size is not adjusted based on unequal randomization, the power of the trial will decrease, whereas with sequential analysis the power will always remain constant. Our aim was to compare sequential boundaries approach with the SSD when the allocation ratio (R) was not equal.