Development and validation of an HPLC method for AG331 bulk drug substance and lyophilized powder for injection

AG331 is a water soluble glucuronate salt of a novel antitumor compound synthesized by protein structure based drug design. A lyophilized powder for injection was developed for clinical studies. During HPLC assay development, AG331 showed an inherent tailing problem due to an amino group in the structure. An optimized reverse-phase gradient HPLC method was developed to minimize the tailing and separate AG331 from its synthetic intermediates (I-1, I-2, I-3, I-4, I-5, I-6, I-8), other impurities and degradation compounds. The method was shown to be linear, precise, accurate, rugged and stability-indicating.     

Neue MR-Techniken in der Neuropädiatrie

Background. Enormous progress has been made in magnetic resonance imaging (MRI) in recent years.This among other things includes the new developments in MR-spectroscopy or diffusion imaging and especially functional MRI, some of which are already in use in clinical practice. Aim of the article. The scope of this article is an introduction to these techniques and their actual and potential applications in pediatrics, especially with regard to CNS-imaging.     

Validation and reproducibility of computerised cell-viability analysis of tissue slices

Background

The identification of live cells using membrane integrity dyes has become a frequently used technique, especially with articular cartilage and chondrocytes in situ where tissue slices are used to assess cell recovery as a function of location. The development of a reproducible computerised method of cell evaluation would eliminate many variables associated with manual counting and significantly reduce the amount of time required to evaluate experimental results.

Methods

To validate a custom computerised counting program, intra-person and inter-person cell counts of nine human evaluators (three groups – unskilled, novice, and experienced) were compared with repeated pixel counts of the custom program on 15 digitised images (in triplicate) of chondrocytes in situ stained with fluorescent dyes.

Results

Results indicated increased reproducibility with increased experience within evaluators [Intraclass Correlation Coefficient (ICC) range = 0.67 (unskilled) to 0.99 (experienced)] and between evaluators [ICC = 0.47 (unskilled), 0.85 (novice), 0.93 (experienced)]. The computer program had perfect reproducibility (ICC = 1.0). There was a significant relationship between the average of the experienced evaluators results and the custom program results (ICC = 0.77).

Conclusions

This study demonstrated that increased experience in cell counting resulted in increased reproducibility both within and between human evaluators but confirmed that the computer program was the most reproducible. There was a good correlation between the intact cell recovery determined by the computer program and the experienced human evaluators. The results of this study showed that the computer counting program was a reproducible tool to evaluate intact cell recovery after use of membrane integrity dyes on chondrocytes in situ. This and the significant decrease in the time used to count the cells by the computer program advocate its use in future studies because it has significant advantages.

     

Is it possible to simulate physiologic loading conditions by applying pure moments? A comparison of in vivo and in vitro load components in an internal fixator

STUDY DESIGN: Loads acting in an internal fixator measured in vitro under the application of pure moments such as those commonly used for implant testing and basic research were compared with loads measured in 10 patients in vivo. OBJECTIVES: To investigate whether these recommended loading conditions are valid by comparing in vivo measurements and those obtained in an in vitro experiment. SUMMARY OF BACKGROUND DATA: Pure bending moments are often preferred as loading conditions for spinal in vitro testing, either for implant testing or basic research. The advantage of this loading pattern is that the bending moment is uniform along the multisegmental specimen. However, functional loading of the spine by muscles or external loads subjects the spine to a combination of forces and moments. METHODS: In an in vivo experiment, loads acting on an internal spinal fixator in 10 patients were determined before and after anterior interbody fusion during flexion, extension, left and right lateral bending, and left and right axial twisting of the upper body with the patient standing. For comparison, an equivalent in vitro data set was created with 7 human lumbar specimens in which the same type of fixator was used. All specimens were tested under the application of pure bending moments in the three main motion planes in the intact state with fixator, after corpectomy, and with bone graft. RESULTS: Consistent qualitative agreement between in vivo and in vitro measurements for the loads acting in the internal spinal fixator were found for axial rotation and lateral bending. For flexion and extension, reasonable agreement was found only for the intact spines with fixators. After corpectomy and after inserting a bone graft, the median values for axial force and bending moment in the sagittal plane in vitro did not agree with in vivo measurements. An axial preload in the in vitro experiment slightly increased the axial compression force and flexion bending moment in the fixators. CONCLUSIONS: The application of pure moments to intact lumbar spinal specimens in vitro produces forces and moments in implants comparable with loads observed in vivo. During basic research on intact specimens or implant testing involving a removed disc or corpectomy, muscle forces are necessary to simulate realistic conditions.     

Bedside Percutaneous Tracheostomy: Clinical Comparison of Griggs and Fantoni Techniques

Elective tracheostomy is widely considered the preferred airway management of patients on long-term ventilation. In addition to open tracheostomy, a number of percutaneous procedures have been introduced during the last two decades, among them techniques according to Griggs (guidewire dilating forceps, or GWDF) and to Fantoni (translaryngeal tracheostomy, or TLT). The aim of the study was to evaluate these two techniques in terms of perioperative complications, risks, and benefits in critically ill patients. A series of 100 critically ill adult patients on long-term ventilation underwent elective percutaneous tracheostomy, either according to the Griggs (n= 50) or Fantoni (n= 50) technique. Tracheostomy was performed under general anesthesia at the patient's bedside. The mean (±SD) operating times were short, 9.2 ± 3.9 minutes (TLT) and 4.8 ± 3.7 minutes (GWDF) on average. Perioperative complications were noted in 4% of patients during either TLT or GWDF and included massive bleeding, mediastinal emphysema, posterior tracheal wall injury, and pretracheal placement of the tracheostomy tube. With regard to oxygenation, pre- and postoperative arterial oxygen tension divided by the fraction of inspired oxygen (PaO₂/FiO₂) ratios did not vary significantly, and no perioperative hypoxia was noted regardless of the technique used. We conclude that both TLT and GWDF represent attractive, safe alternatives to conventional tracheostomy or other percutaneous procedures if carefully performed by experienced physicians and under bronchoscopic control.     

Surgical treatment of gastric cancer: retrospective survey of 1,704 operated cases with special reference to total gastrectomy as the operation of choice.

Total gastrectomy is discussed as the operation of choice among different surgical approaches for gastric carcinoma. We prefer the performance of an elective total gastrectomy with systematic lymphadenectomy (compartments I and II) and obligatory splenectomy. A retrospective study of 1,704 consecutive cases of gastric carcinomas showed a better outcome following total gastrectomy in relationship to distal subtotal gastrectomy, but these results cannot be used as evidence because of the lack of a prospective study. Nevertheless, a precise analysis of our cases in regard to tumor site and tumor type could show a frequency of only 6% to maximally 30%, in which elective total gastrectomy may represent a procedure too extensive to justify for an oncological course.     

Statistical implications of utility weighted and equally weighted HRQL measures: an empirical study

The utility‐based approach to health measurement, exemplified by EQ‐5D and Health Utilities Index (HUI), has been challenged on a theoretical basis, but the statistical implications of such an approach have received little attention. To empirically investigate this issue, psychometric properties and statistical efficiency of the EQ‐5D and HUI Mark 3 (HUI3) classifiers were compared when scored using preference weighted (WPS) and equally weighted summary scores using two longitudinal datasets (n_stroke=124; n_{rehabilitation}=264). Test–retest reliability, construct validity, responsiveness, and relative efficiency (RE) ratios (with bootstrapped 95% confidence intervals) were examined. WPS had slightly lower test–retest reliability, particularly for EQ‐5D (intraclass correlation coefficient=0.61 vs 0.72). For known‐groups comparisons, WPS had greater inferential power for both EQ‐5D and HUI3 (RE>1). No significant differences in sensitivity to change were observed for EQ‐5D [0.71 (95% CI: 0.29,1.33)≤RE≤0.96(95% CI: 0.69,1.32)] or HUI3 [0.97 (95% CI: 0.89,1.03)≤RE≤1.23 (95% CI: 0.98,1.72)]. Implications of weighted scoring will depend on whether the weights are greater or less than equal weights where patients fall along the health state classifier continuum. Because utility weights can affect the statistical properties and significance of results, the summary score selected should be appropriate to the purpose of the study and population of interest. Copyright © 2009 John Wiley & Sons, Ltd.