In vitro dissolution characteristics of aged and recrystallised high-fired 232ThO2

The dissolution characteristics of 232Th from ThO2 in the lung have been determined in an in vitro study. Two types of ThO2 were examined to determine if the age of the material had any effect; an aged high-fired ThO2 that had its progeny in secular equilibrium, and a recently recrystallised and high-fired ThO2 in disequilibrium. The results show the amount of 232Th that dissolved from the aged ThO2 was approximately 10 times greater than the amount that dissolved from the recrystallised and fired ThO2 which was the result of recoil damage to the crystal structure of the aged material. A model based on nuclear track theory was developed to relate the size of the observed rapidly soluble fraction of 232Th to the age of the material and its experimentally determined surface area.     

Identification and characterization of Saccharomyces cerevisiae strains isolated from West African sorghum beer

The occurrence and characterization of yeasts isolated from sorghum beer produced in Ghana and Burkina Faso, West Africa, were investigated. The yeasts involved in the fermentations were found to consist of Saccharomyces spp. almost exclusively. Of the isolates investigated, 45% were identified as Saccharomyces cerevisiae, whereas more than half of the isolates (53%) had physiological properties atypical of S. cerevisiae or any other member of the complex sensu strictu, as they were able to assimilate only glucose, maltose and ethanol as carbon sources. Both ITS-PCR RFLP and PFGE strongly indicated that these isolates were related to S. cerevisiae, regardless of their phenotypic characteristics. Sequencing of the D1/D2 domain of the 26S rDNA confirmed the close relatedness to S. cerevisiae with 0.5% nucleotide differences. The MAL1 and MAL3 loci were found for all isolates as the only recognized MAL loci. Besides, for 40% of the isolates the MAL61 probe hybridized to a position of about 950 kbp, which has not formerly been described as a MAL locus. The results showed that the spontaneous fermentation of West African sorghum beer is dominated by a variety of strains of S.cerevisiae not previously described, among which starter cultures should be selected.     

The CTFA Evaluation of Alternatives Program: an evaluation of in vitro alternatives to the Draize primary eye irritation test. (Phase III) surfactant-based formulations

The CTFA Evaluation of Alternatives Program is an evaluation of the relationship between data from the Draize primary eye irritation test and comparable data from a selection of promising in vitro eye irritation tests. In Phase III, data from the Draize test and 41 in vitro endpoints on 25 representative surfactant-based personal care formulations were compared. As in Phase I and Phase II, regression modelling of the relationship between maximum average Draize score (MAS) and in vitro endpoint was the primary approach adopted for evaluating in vitro assay performance. The degree of confidence in prediction of MAS for a given in vitro endpoint is quantified in terms of the relative widths of prediction intervals constructed about the fitted regression curve. Prediction intervals reflect not only the error attributed to the model but also the material-specific components of variation in both the Draize and the in vitro assays. Among the in vitro assays selected for regression modeling in Phase III, the relationship between MAS and in vitro score was relatively well defined. The prediction bounds on MAS were most narrow for materials at the lower or upper end of the effective irritation range (MAS = 0-45), where variability in MAS was smallest. This, the confidence with which the MAS of surfactant-based formulations is predicted is greatest when MAS approaches zero or when MAS approaches 45 (no comment is made on prediction of MAS > 45 since extrapolation beyond the range of observed data is not possible). No single in vitro endpoint was found to exhibit relative superiority with regard to prediction of MAS. Variability associated with Draize test outcome (e.g. in MAS values) must be considered in any future comparisons of in vivo and in vitro test results if the purpose is to predict in vivo response using in vitro data.     

Success of surgery for primary aldosteronism judged by residual autonomous aldosterone production

Since February 1996 we have prospectively assessed residual adrenal autonomy by the fludrocortisone suppression test (FST) in 23 patients 3 months after unilateral adrenalectomy for Conn syndrome and in 45 patients after a longer interval. In regard to blood pressure, 36 (53%) patients were cured of hypertension and the remaining 32 (47%) patients had improved hypertension control at the time of their latest postoperative clinical assessment. In regard to the outcome of surgery, patients who achieved normal suppressibility of aldosterone were regarded as cured, and those who had greater suppressibility after surgery were considered improved. Time since surgery for the whole group averaged 26 months. By these biochemical criteria, 42 patients (62%) were cured by surgery, and the rest improved; 16 (76%) of 21 women were cured, and 26 (55%) of 47 men. The women (mean +/- SD age 47 +/- 11 years) were significantly (p < 0.05) younger than the men (52 +/- 9 years). Preoperative aldosterone levels before and after FST were similar in the cured and improved groups and fell significantly (p < 0.01) in both groups following surgery. After surgical reduction of autonomous aldosterone production, mean plasma renin activity levels increased sixfold in the cured group and threefold in the improved group. Surgical mortality in this group of 68 patients with Conn syndrome was zero.     

Electromagnetic compatibility aspects of active robotic systems for surgery: the robotic prostatectomy experience

This case describes ventricular proarrhythmia as a result of a synchronized internal atrial defibrillation shock in a 29-year-old man with Ebstein's anomaly referred for radiofrequency ablation of a right posterior accessory pathway. During the electrophysiologic study, atrial fibrillation was induced and 3/3 msec shocks of various strengths were delivered between two decapolar defibrillation catheters in the coronary sinus and right atrial appendage. A 2.0-J biphasic shock synchronized to an R wave after a short-long-short ventricular cycle length pattern with a preshock coupling interval of 245 msec induced ventricular fibrillation, which was externally defibrillated with 200 J. This observation has implications for the development of implantable atrial defibrillators.     

Cytokine priming reduces dependence on TNF-R2 for TNF-alpha-mediated induction of macrophage nitric oxide generation

In the presence of interferon-gamma (IFN-gamma), human tumor necrosis factor-alpha (Hu-TNF-alpha), which binds to murine TNF-alpha receptor type 1 (TNF-R1) but not to murine TNF-R2, was effective in inducing nitric oxide (NO) production in spleen-derived macrophages (M phi), albeit at concentrations 12.5-fold greater than those required by murine TNF-alpha (Mu-TNF-alpha), to achieve the same result. Addition of anti-TNF-R1 completely inhibited the Mu-TNF-alpha-mediated induction of NO, demonstrating that TNF-R1 is critical to the IFN-gamma-dependent TNF-alpha-mediated induction of M phi effector function. However, treatment with anti-TNF-R2 resulted in a partial inhibition of M phi activation. Spleen-derived M phi were more dependent on TNF-R2 than RAW 264.7 or peritoneal M phi based on their responsiveness to Hu-TNF-alpha. Priming of spleen-derived M phi with either IFN-gamma or granulocyte-macrophage colony-stimulating factor (GM-CSF) heightened the maximal responses to both TNF-alpha species and increased the overall effectiveness of Hu-TNF-alpha without increasing expression of either TNF-alpha receptor. The dependence of spleen-derived M phi on both TNF-alpha receptors for signaling the induction of effector function supports an active signaling role for TNF-R2 in its synergy with TNF-R1 rather than a passive ligand passing role.