Bevacizumab as an adjunct to vitreoretinal surgery for diabetic retinopathy in East Africa.

PURPOSE: The purpose of this study is to evaluate the efficacy of preoperative intravitreal bevacizumab (IVB) for improving outcomes in vitrectomy for diabetic retinopathy-related non-clearing vitreous haemorrhage and/or tractional retinal detachment. METHODS: Medical record from patients undergoing vitrectomy for proliferative diabetic retinopathy (PDR) were retrospectively analysed (2003-2011). From 2007, IVB (1.25 mg 2-4 days before operating) was used on all eyes. Eyes receiving IVB were compared with those that did not receive IVB. Intraoperative complications, reoperation rates, and final visual acuity were the core outcome measures. RESULTS: Data were analysed for 88 patients (101 eyes). In all, 41 (41%) patients had received IVB, whereas 60 (59%) patients had not. Significant intraoperative haemorrhage occurred in six eyes (10%) in the non-IVB group and in one (2.4%) IVB eyes (P=0.24). Silicon oil was used in 29 (48%) non-IVB eyes and in 11 (27%) IVB eyes (P=0.03). The non-IVB eyes underwent significantly more vitreoretinal reoperations (P=0.01) and were significantly more likely to lose two or more lines of vision at the final follow-up (P=0.03). The numbers needed to treat (NNT) blindness (<3/60) was four for non-IVB eyes and two for the IVB group. CONCLUSIONS: IVB reduces surgical complications, the use of silicon oil, and the need for further retinal surgery. The NNT to restore useful vision (≥3/60) to a blind eye were significantly lower in the IVB group. Vitreoretinal surgery for the complications of PDR is effective in an East African context, and IVB should be considered a valuable adjunct.

Fluoride: how to maximize the benefits and minimize the risks.

This article reviews current thinking on the rational use of fluoride for the safe and effective prevention of dental caries, so that benefits may be maximized and risks minimized.

A new large-scale process for taxol and related taxanes from Taxus brevifolia.

PURPOSE: In view of the demonstrated antitumor activity of taxol, ready availability of the drug is important. The current isolation methods starting from the bark of Taxus brevifolia involve multiple manipulations, leading to only taxol and in a yield of 0.01%. A new process consisting of a single reverse phase column is introduced here, and the present purpose is to determine its large scale applicability. METHODS: The chloroform extractable fraction of the bark of T. brevifolia is applied directly on to a C-18 bonded silica column in 25% acetonitrile/water, with elution using a step gradient: 30-50% acetonitrile/water. On standing, eight different taxanes, including taxol, crystallize out directly from different fractions. The crystals are filtered and purified further by recrystallization. Taxol and four other taxanes are purified this way. The other three require a short silica column. Taxol is freed from cephalomannine by selective ozonolysis. RESULTS: The large scale process gave taxol (0.04%), 10-deacetylbaccatin III (0.02%), 10-deacetyl taxol-7-xyloside (0.1%), 10-deacetyl taxol-C-7-xyloside (0.04%), 10-deacetyl cephalomannine-7-xyloside (0.006%), taxol-7-xyloside (0.008%), 10-deacetyl taxol (0.008%) and cephalomannine (0.004%). Processing of the needles of T. brevifolia gave brevifoliol (0.17%), and that of the wood, 10-deacetyl taxol-C-7-xyloside (0.01%) and 10-deacetyl taxol-C. CONCLUSIONS: The reverse phase column process is simpler (one column, direct crystallization), more efficient (eight taxanes obtained simultaneously) and also gives higher yields.

Specific absorption rate and tissue temperature in local hyperthermia.

Specific absorption rate (SAR) and tissue temperature were measured for a total of 83 treatments in 33 patients who received local hyperthermia treatment for cancer. The patients were grouped into three categories according to tumor size. Hyperthermia was induced by 13.56 MHz electromagnetic energy applied using capacitive coupling. A method is described for evaluating SAR from the tissue temperature traces at any time in the treatment when a step change is made in applied power. The method is possible only if the temperature traces are free from interference and the total power delivered to the patient is monitored. Mean values of SAR ranged from 4.6 to 89 W kg-1 depending on the treatment site. Satisfactory heating was achieved for superficial tumors, with temperatures greater than 42 degrees C being recorded in 69% of treatments. For axillary nodes only 4% of treatments exceeded 42 degrees C. For cervix tumors an idealized tumor model was used to estimate tumor temperature from the temperature and SAR measured in the adjacent normal tissue. From the model it appears necessary either to raise the systemic temperature to 40 degrees C or to increase the SAR by at least a factor of 4 to obtain a temperature of 42 degrees C in a typical tumor. Measurements of SAR and temperature are essential for feedback control of computer models which, in principle, could provide a complete distribution of temperature during a hyperthermia treatment. Furthermore, measured SAR provides a direct comparison of the power deposition from different treatment machines in a clinical environment. The data presented form a basis for comparison with the clinical use of other heating systems.