Baseline characteristics and treatment preferences of oral surgery patients.

PURPOSE: Patient preferences for treatment choices may depend on patient characteristics. Using standard gamble (SG) and willingness to pay (WTP), this study compares preferences for treatment of mandibular fracture among patients in a low-income urban area. PATIENTS AND METHODS: Surveys of African-American and Hispanic adults receiving treatment at King/Drew Medical Center for either mandibular fracture (n = 98) or third molar removal (n = 105) were used to investigate differences in patient characteristics across treatment groups (third molar vs fracture) and treatment preference (wiring vs surgery). RESULTS: The fracture patients were willing to pay more to restore function without scarring or nerve damage than were the third molar patients. Patients who chose surgery were willing to accept a greater risk of possible nerve damage or scarring than those who chose wiring. Among 15 potential predictors of SG and WTP studied in 4 subgroups defined by actual treatment and treatment preference, significant predictors varied, with associations for education and clinical experience for SG and associations with income and psychosocial predictors for WTP. CONCLUSIONS: SG and WTP capture different domains of health values in patients. There is considerable heterogeneity in relationships among patient characteristics and patient preferences across subgroups defined by actual treatment and treatment preferences.     

Investigation of central visual fields in patients with age-related macular changes

The effect of early macular pigmentary and drusen changes on the central visual field was investigated in elderly patients with normal visual acuities. Visual field measurements were taken with the Humphrey Field Analyser using its 24-2 and 10-2 full threshold programs. No significant differences were found between two patients groups, one with and one without the macular changes. We conclude that fine pigmentary changes and hard drusen do not cause changes in visual functioning and can be accepted as normal age-related changes.     

Refractive errors induced by displacement of intraocular lenses within the pseudophakic eye

Simple methods were developed to estimate refractive errors when intraocular lenses are not fitted optimally within pseudophakic eyes. The accuracy of these methods was determined by comparing results obtained with them to results obtained by raytracing through a model eye. Accuracy was good for longitudinal displacement and tilting, and reasonable for transverse displacement. Refractive errors are related linearly to the magnitude of the longitudinal displacement, and are related to the square of the magnitude of tilt or transverse displacement. The refractive error upon transverse displacement is quadratically dependent upon lens shape.     

FM sonography in diffuse liver disease: prospective assessment and blinded analysis

FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.     

Transmitter, ion channel and receptor properties of pheochromocytoma (PC12) cells: a model for neurotoxicological studies.

The increased desire to use in vitro techniques in neurotoxicology has resulted in the search for clonal cell lines which may be useful for studying disruption by neurotoxicants of various aspects of neuronal physiology and biochemistry. One such cell line is the PC12 cell, a clonal cell line derived from a pheochromocytoma of the rat adrenal medulla. When cultured under normal conditions, PC12 cells resemble adrenal chromaffin cells in morphology, physiology and biochemistry. However, when cultured in the presence of nerve growth factor (NGF) or several other compounds, PC12 cells differentiate to resemble sympathetic neurons morphologically and functionally. Differentiation and the resultant physiological and biochemical changes are some of the most attractive and useful features of this cell line. PC12 cells release, depending on the conditions, dopamine, norepinephrine and acetylcholine and contain Na, K and Ca channels and other membrane receptors, including receptors coupled to G-proteins. Moreover, the relative proportion of various subtypes of Ca channels changes during differentiation. Thus, PC12 cells provide an excellent model for studying chemical disruption of processes associated with neuronal differentiation, synthesis, storage and release of neurotransmitters, function and regulation of ion channels and interactions of compounds with membrane bound receptors. The ability of PC12 cells to differentiate in response to NGF and other compounds allows for selective expression of certain channels and proteins and for comparisons of responses in undifferentiated and differentiated cells. The prominent neurotoxicant methylmercury causes potent reductions in uptake of 45Ca and binding of ligands associated with various subpopulations of Ca channels in the PC12 cells, as well as currents carried through putative Ca channels.     

Pneumothorax and other lung diseases: effect of altered resolution and edge enhancement on diagnosis with digitized radiographs

Prior studies have shown that pneumothorax is one of the more difficult entities to diagnose with digitized radiography. This study was designed to test whether increasing resolution from 1.25 to 2.5 line pairs per millimeter (lp/mm) and image processing (edge enhancement from unsharp masking) would increase accuracy and confidence in the diagnosis of pneumothorax, as well as normal cases and other forms of lung disease. Conventional radiographs were digitized with use of a laser reader and then reformatted as film hard copy. Eleven observers read 35 cases reformatted in three different ways (1.25 lp/mm, 2.5 lp/mm, 1.25 lp/mm unsharp mask). The images with finer resolution (2.5 lp/mm) and unsharp mask images were superior to those with coarser resolution (1.25 lp/mm) for the diagnosis of pneumothorax. There was no difference in diagnostic accuracy for normal patients. For abnormalities other than pneumothorax, the unsharp mask images were significantly worse. Confidence in the diagnosis of pneumothorax and other abnormalities was highest with the finest resolution (2.5 lp/mm).     

Alterations of spontaneous and evoked release of acetylcholine during dithiobiuret-induced neuromuscular weakness

Daily treatment of rats with 2,4-dithiobiuret (DTB, 1 mg/kg/day i.p.) produces a flaccid neuromuscular weakness first observed in the hindlimbs after 5 to 6 days of treatment. This condition is characterized by diminished contractile strength following single shock and tetanic stimulation of the motor nerve, but no effect on contractions evoked by direct muscle stimulation, indicating an apparent impairment of motor axon conduction, junctional transmission or both. The purpose of the present study was to investigate further the neuromuscular depression caused by DTB using conventional intracellular microelectrode recording techniques. All experiments were conducted using the extensor digitorum longus muscle isolated from male rats treated for 6 to 7 days with 1 mg/kg/day i.p. of DTB or with 0.9% NaCl (1 ml/kg/day) as control. End-plate potentials (EPPs) and miniature end-plate potentials (MEPPs) were recorded from single junctions of DTB-poisoned or NaCl-treated paired controls. Muscles were transected ("cut muscle") to prevent contraction after peroneal nerve stimulation. EPP amplitude was decreased at the time of observable muscle weakness in DTB-treated rats. Endplate resting membrane potential was not affected. Decreased EPP amplitude was associated with a decrease in mean quantal content. Quantal content was depressed to an equivalent extent in DTB-treated rats when stimulus frequency was increased from 0.5 to 2, 5, 25 and 50 Hz. However, as the stimulus frequency was increased, preparations from DTB-treated rats were characterized by failures of nerve impulses to elicit an EPP.(ABSTRACT TRUNCATED AT 250 WORDS)     

CD40 expression by gingival fibroblasts: correlation of phenotype with function

CD40, a member of the tumor necrosis factor-alpha receptor family, is constitutively expressed by cells of hematopoietic and non- hematopoietic origin, including fibroblasts. Signaling through this receptor molecule regulates inflammatory cytokine secretion by many cell types. Based on the recently described cytokine secretory heterogeneity of fibroblast cell subsets, we hypothesized that secretion of inflammatory cytokines by gingival fibroblast cultures may be dictated by the existence of differential proportions of cytokine- secreting subpopulations which express high levels of CD40. After examining a large number of gingival fibroblast (GF) cultures we find that the frequency of IL-6- and IL-8-secreting cells mirrors the frequency of cells expressing high levels of CD40 in these cultures. In addition, we demonstrate a direct functional relationship between CD40 expression and IL-6 or IL-8 secretion by showing that ligation of this molecule on GF, and CD40+ fibroblast subsets in particular, up- regulates secretion of these cytokines in vitro.