Application of oxybutynin selective sensors for monitoring the dissolution profile and assay of pharmaceutical dosage forms.

Two ion-selective sensors of the plastic membrane type were prepared for the determination of oxybutynin hydrochloride (OxCl). They depend on the incorporation of the ion-associates with phosphotungestic acid or phosphomolybdic acid in a PVC matrix. A comparative study is made between their performance characteristics in batch and FIA conditions. The sensors have nearly the same usable concentration, temperature and pH range. They have a wide range of selectivity and can be applied for the determination of the relevant drug with nearly the same precision and accuracy in vitro. Dissolution testing was applied using the sensors; this offers a simple, rapid, cheap way out of sophisticated and high cost instruments used in the pharmacopeial method using HPLC. The investigated drug was determined in its pure and pharmaceutical preparations. The results were accurate and precise, as indicated by the recovery values and coefficients of variation.

Aspects of mandibular morphology, with specific reference to the antegonial notch and the curve of Spee.

The purpose of this investigation was to determine whether particular metrical traits of the mandibular antegonial notches are associated with specific mandibular growth patterns, and also with the mean depth of the curve of Spee. Thirty pre-treatment lateral cephalometric radiographs belonging to a randomly selected group of patients treated in the orthodontic clinic at the SUNY at Buffalo were digitized. The surface areas of the mandibular antegonial notches, as well as some sagittal facial dimensions were measured on each radiograph. The curve of Spee was measured directly from the pre-treatment mandibular study cast of each patient included in this study. An analysis of variance showed no statistically significant difference (p < 0.01) between the measurements recorded by the two examiners who conducted this study. The results of this study showed a statistically significant positive correlation between the surface areas of the antegonial notches and the lower anterior facial heights (r = 0.87, P < 0.001). At the same time a statistically significant negative correlation was found between the surface areas of the antegonial notches and the lengths of the mandibular bodies (r = -0.9, P < 0.001). A significant negative statistical relationship was shown to exist between the lower anterior facial heights and the lengths of the corresponding mandibular bodies, and also between the depths of the curves of Spee and the surface area of the respective antegonial notches (r = -0.85, P < 0.002). The results of this study indicate that an increase in the areas of the antegonial notches is associated with a tendency for greater vertical growth of the mandible. The results further suggest that the depth of the curve of Spee and the length of the mandibular body are decreased when there is an increase in the surface areas of the antegonial notches.

Head posture and deprivation of visual stimuli.

INTRODUCTION: Natural head position (NHP) has been defined as the cranial position that is attained when individuals stand with their visual axes in the true horizontal plane. The visual axis is considered to be a key component in establishing, and maintaining NHP so that, in the absence of visual stimuli, gravitation and muscular proprioception chiefly control head position. SUBJECTS AND METHODS: In this study, the natural head positions of a group of normal sighted subjects were measured in a well-lighted room. The findings were compared to similar observations made in the same subjects when they were placed in a completely dark environment. Measurements of cranio-cervical angulation were made on adults (N = 30, males = 17, females = 13) by means of an electronic inclinometer. Sitting Head Position (SIHP), Standing Head Position (STHP), and Orthoposition (OP) were determined for each subject in a well-lighted room, and subsequently, in a completely dark room. RESULTS: The data indicate that there were statistically significant differences between Standing Head Position, and Orthoposition, measured in the light and in the dark. There were no statistically significant differences between Sitting Head Position measured in the light and in the dark. CONCLUSION: The results indicate that craniocervical angulation is more extended in the dark than it is in the light. This finding suggests that head position responds to visual stimuli, and that when this sensory input is not present, there is a tendency for subjects to extend their heads.