Radiographic examinations of orthodontic educators and practitioners

Orthodontic educators and practitioners were surveyed to determine the radiographs each prescribes to diagnose Class II malocclusion patients. Results of the study were based on 141 responses. The frequency of ordering each of ten radiographic projections and the importance of these radiographs to the orthodontists' diagnosis and treatment planning were measured. A lateral cephalometric and panoramic film were found to be the most frequently ordered and the most diagnostically important radiographs. Differences between the two groups were found regarding their use of supplementary radiographs. Educators were found to order more radiographs for their patients.     

Investigation of profile difference between Alzheimer's disease patients declining at different rates: examination of baseline neuropsychological data.

The rate of cognitive decline in AD has been noted to vary significantly among patients. The ability to predict the probable rate of decline early in the disease process would be of great practical importance. Attempts to analyze early cognitive deficits to find patterns associated with rapid decline have met with limited success. This paper utilized a large sample of patients with a diagnosis of probable AD evaluated longitudinally in ongoing research at the ADRC at Baylor College of Medicine and a statistical procedure of profile analysis to assess the initial data for a pattern associated with rapid decline. The findings indicated that despite initial equality of MMSE scores, patients showing rapid MMSE decline at one year displayed significantly more impaired performance on neuropsychological measures at diagnosis. Discussion includes discussion on the use of the MMSE for tracking general cognitive function and the difficulties of ascertaining stable profiles for prediction.     

Serum and plasma from patients with Lambert-Eaton myasthenic syndrome reduce depolarization-dependent uptake of Ca into rat cortical synaptosomes

The reduction in nerve-evoked release of transmitter at the neuromuscular jkunction of patients with Lamber-Eaton Myasthenic Syndrome (LEMS) is thought to be caused by a circulating autoantibody to calcium channels of presynaptic motor nerve terminals. Studies were undertaken to determine whether acute application of plasma and serum from patients with LEMS or small cell carcinoma (SCC) would reduce depolarization-dependent uptake of ⁴⁵Ca²⁺ into isolated nerve terminals of the central nervous system (CNS). Net potassium-stimulated influx was reduced by sera and plasma from patients with LEMS but not by sera from patients with SCC. Lactate dehydrogenase (LDH) release from synaptosome incubated with plasma or serum from patients with LEMS was not increased over control. These results are significant because: (1) they demonstrate that acute exposure to a circulating factor in sera/plasma from a patient with LEMS is sufficient to inhibit Ca²⁺ channel activity in isolated nerve terminals, as opposed to chronic regimens used on other models for the disease; (2) they indicate that the existence of SCC alone is insufficient to trigger a LEMS-like autoimmune response; (3) they suggest that Ca²⁺ channels of nerve terminals secreting different transmitters may share common epitopes recognized by the LEMS autoantibody; and (4) they suggest that synaptosomes will be useful determining the neurochemical site and specificity of the LEMS autoantibody.     

Possible errors in determining axial length changes during accommodation with the IOLMaster.

PURPOSE: The Zeiss IOLMaster uses partial coherence interferometry to measure the optical path length within the eye. This is converted into the axial length. There are errors in measuring possible changes in axial length as a result of accommodation, because the instrument uses an average refractive index in the eye. We determined the likely extent of these errors. METHOD: Errors were estimated using Gullstrand's no. 1 schematic eyes. One set of these had the shell structure of the eyes, and another set had the gradient index structure specified by Gullstrand. RESULTS: Errors were 18 to 26 microm for an accommodation of 10.9 D. CONCLUSIONS: The worth of the IOLMaster would be increased if it used an equation for conversion from optical length to geometrical length that took into account variations in lens thickness and if it were able to be modified to provide component distances and the axial length using partial coherence tomography.     

Effect of injection rate on level and duration of hypobaric spinal anesthesia

The purpose of this study was to determine whether injection rate affects the spread of hypobaric spinal anesthesia. Hypobaric spinal anesthesia was performed on 20 patients for total hip arthroplasty. Dural puncture was performed with a 22-gauge Whitacre needle. All patients received 10 mg of hypobaric tetracaine with epinephrine. An electrically driven syringe pump was used to inject the anesthetic solution at either slow (250 sec) or fast (10 sec) rates. Ten patients received slow injections, and 10 received fast injections. Anesthetic levels, duration of anesthesia, and specific gravities of injectate and CSF were measured. Slow injection resulted in less spread of spinal anesthesia. Four-segment regression of anesthetic levels took significantly longer in the slow injection group. Local anesthetic mixtures used were consistently hypobaric compared to patient CSF. We conclude that slow injection of hypobaric tetracaine through a 22-gauge Whitacre needle produces lower levels of spinal anesthesia that tend to be of longer duration than levels resulting from fast injection.