An In Situ Dissolution Study of Aspirin Crystal Planes (100) and (001) by Atomic Force Microscopy

Purpose. To observe in situ and on individual aspirin crystal faces the comparative rates and processes of dissolution of the dominant faces. Methods. The kinetics of the dissolution rate of two aspirin crystal planes (001) and (100) under 0.05M HCl are studied in situ at room temperature using Atomic Force Microscopy. The dissolution process of each crystal plane was followed by observed changes in topographic features. Results. The results revealed that crystal plane (001) dissolves by receding step edges, and has a dissolution rate of 0.45 nm s^–1. Conversely, plane (100) displays crystal terrace sinking at an average rate of 2.93 nm s^–1. Calculated intrinsic dissolution values (g s^–1 cm^–2) for planes (001) and (100) are 1.37 × 10^–7 g s^–1 cm^–2 and 8.36 × 10^–7 g s^–1 cm^–2, respectively. Conclusions. These values indicate that the rate of flux of material from plane (100) is approximately six times greater than that from plane (001), under 0.05M HCl. Interpretation of the data, based upon intrinsic dissolution rates and dissolution rate velocities, correlate with reported variations in the dissolution behavior of commercial aspirin products. These observations illustrate the suitability of the technique for characterizing the dissolution behavior of crystalline drugs.     

The frequency of pseudoexfoliation syndrome in the eastern Mediterranean area of Turkey.

In this study we evaluated the frequency of pseudoexfoliation syndrome, the percentages of glaucoma and senile cataract in patients with and without pseudoexfoliation syndrome, and the percentages of pseudoexfoliation syndrome in patients with glaucoma and senile cataract in the Eastern Mediterranean area of Turkey. We examined 1356 persons over 40 years of age. Frequency of pseudoexfoliation syndrome in the greater than or equal to 50 years old age band was 7.2%, and there was a statistically significant difference between the sexes. Over 60 years of age, the frequency of pseudoexfoliation syndrome was 11.2%, the percentage of glaucoma in patients with pseudoexfoliation syndrome was 34.3%, the percentage of pseudoexfoliation syndrome in patients with glaucoma was 46.9%, the percentage of cataract in persons with pseudoexfoliation syndrome was 88.1%, and the percentage of pseudoexfoliation syndrome in persons with cataract was 17.7%. The differences between the percentage of glaucoma and cataract in patients with and without pseudoexfoliation syndrome, were both statistically significant (p less than 0.001).     

Ifosfamide encephalopathy

We describe a case of reversible encephalopathy caused by the recently released anticancer drug Ifosfamide. The clinical course, role of EEG in monitoring and predicting encephalopathy, and putative mechanism of neurotoxicity is discussed. Short infusion times and/or prior CNS disease may increase the risk of encephalopathy.     

Associations between differential leucocyte count and incident coronary heart disease: 1764 incident cases from seven prospective studies of 30,374 individuals.

AIMS: We aimed to assess potential associations between different leucocyte components and coronary heart disease (CHD) in a prospective cohort study, and to put these findings in context of other relevant prospective studies in a meta-analysis. METHODS AND RESULTS: We report data on differential leucocyte count and CHD derived from the first National Health and Nutrition Examination Survey (NHANES I) and the NHANES 1 Epidemiologic Follow-up Study (NHEFS) involving 4625 individuals followed, on average, for 18 years. The NHEFS involved 914 incident CHD cases and yielded an adjusted risk ratio of 1.09 (0.93-1.29) comparing individuals with neutrophil counts in the top third versus those in the bottom third of the population. In a meta-analysis involving the NHEFS and four other studies comprising a total of 1764 incident CHD cases, the association of CHD with neutrophil counts was somewhat stronger than those with other specific leucocyte components (combined risk ratio=1.33 [1.17-1.50]) but there was substantial heterogeneity between the separate studies (Chi2(4), p <0.001). CONCLUSIONS: Although the present synthesis provides the most comprehensive assessment so far of specific leucocyte components in CHD, additional prospective data will be needed to resolve whether neutrophil counts are much stronger predictors of CHD risk than other components.     

Immediate dental and skeletal influence of distractor position on surgically assisted rapid palatal expansion with or without pterygomaxillary disjunction

The outcome of surgically assisted rapid palatal expansion (SARPE) can be affected by pterygomaxillary disjunction (PMD) and the distractor position. In this study, SARPE was performed, with or without PMD, in 20 fresh cadaver heads. Transverse expansion was conducted twice using a bone-borne distractor in the anterior and posterior positions, resulting in four groups (n = 10). Cone beam computed tomography scans were completed before and after SARPE to evaluate maxillary changes. A comparative anterior decrease and posterior increase in midpalatal opening resulted from SARPE with PMD combined with a posteriorly placed distractor. Significant differences in the internal transverse changes were found between the two SARPE techniques combined with an anterior distractor at the level of the premolars and molars for alveolar ridge width (P = 0.040, P = 0.024), and at the level of the molars for the dental crown width (P = 0.017) and corresponding tooth cusp width (P = 0.018). In contrast, using a posteriorly placed distractor led to a significant difference for tooth cusp width only (P = 0.050). No statistically significant differences were found between external transverse changes or between distractor positions. PMD is more important in achieving a more uniform and parallel transverse expansion pattern than the distractor position. However, a posterior distractor seems to intensify the effects of PMD.     

Influence of bone density,screw size and surgical procedure on orthodontic mini-implant placement – part B: implant stability

This in vitro study aimed to investigate the influence of bone density, implant size, and surgical procedure on the primary stability (PS) of orthodontic mini-implants (OMIs). In total, 640 OMIs of various sizes (2.0 × 7, 2.3 × 7, 2.0 × 11 and 2.3 × 11 mm) were inserted in the artificial bone of different densities (D1–D4). Placement was performed with an insertion angle of 90° or 60° to the bone surface and in 320 cases without predrilling, which resulted in 64 groups. PS was measured on the basis of implant stability quotient (ISQ) and insertion torque (IT). With regard to all possible influencing parameters, the mean PS differed between 39.20 and 60.00 (ISQ), and 10.00 and 39.00 Ncm (IT). The effect of OMI size and surgical procedure was dependent on bone quality. For example, implant size had less effect in high-density bone and was stronger with decreasing density. Overall, implant length had a greater influence than the diameter, and a high correlation was found among both PS measurement techniques. Therefore, a suitable choice of implant size and surgical protocol with regard to bone density can positively influence PS. In principle, ISQ and IT are suitable for measuring OMI stability.