Faculty Bibliography

Using a sample of 267 deaf adults, members of a stigmatized collective, this study tested three notions: (a) The ecological context in which group members live affects identification with their group; (b) group identification has a positive effect on members' self-esteem; and (c) several psychological mechanisms mediate between group identification and self-esteem. The first two notions received support. Family and school deafness were associated with group identification, which, in turn, had a positive effect on self-esteem both directly and through its moderating effect on the negative relationships between several variables and self-esteem. Data did not provide support, however, for the proposal that several variables mediate between group identification and self-esteem. Results highlight the importance of considering both the personal ecology of participants and their social-political context, as well as suggest revisions in theories on group identification and self-esteem

The principle of distraction osteogenesis, well-established in the enchondral bones of the axial skeleton, has recently been applied to the membranous bones (mandible, cranium) of the craniofacial skeleton in the experimental animal and in the human. In the craniofacial skeleton, however, the technique has been used only to lengthen bone in a direction along its major axis, i.e., unidimensional distraction. A canine model is presented to demonstrate the feasibility of distracting membranous bone away from its dominant axis, i.e., multidimensional distraction. Four mongrel dogs, 5 months of age, were the subjects of this study. Two osteotomies were made in the zygomatic arch, and the bone-lengthening device was fixed to the zygoma. After 7 days of external fixation, the osteotomized segment was lengthened 1 mm/day away from the long axis of the bone for 15 days. External fixation was then maintained for a minimum of 4 weeks, after which the dogs were sacrificed. Craniofacial CT with three-dimensional reconstruction documented multidimensional bone lengthening, and histologic analysis of the specimen confirmed the presence of new cortical bone in the expanded areas. Refinement in technique and miniaturization and internalization of the bone-lengthening device may allow for more precise changes in the amount and direction of lengthening, thus making distraction osteogenesis more widely applicable for use in the human craniofacial skeleton

The goal of this study was to determine the distribution and diversity of astrocytes and oligodendrocytes within the lateral superior olive of the gerbil. We used morphometric analyses and several immunocytochemical markers to assess differences in glial cell composition between the lateral (low-frequency projection) and the medial (high-frequency projection) limb of the lateral superior olive. Cell counts from Toluidine-stained semithin sections revealed a similar density of total astrocytes in both the lateral and the medial limbs. However, based on cytologic features, there was a prevalence of fibrous-like astrocytes in the lateral limb and protoplasmic-like astrocytes in the medial limb. In a similar manner, glial fibrillary acidic protein staining of astrocytes was intense in the lateral limb, but was largely restricted to the nucleus borders in the medial limb of the lateral superior olive. While glial fibrillary acidic protein was largely restricted to astrocytic processes, glutamine synthetase and S100 protein staining occurred, for the most part, in glial cell bodies. The density of glutamine synthetase positive cell bodies was homogeneous between the two limbs, while the density of S100-positive somata was significantly greater in the lateral limb. Cell counts obtained from semithin sections demonstrated a greater density of oligodendrocytes in the lateral limb than in the medial limb of the lateral superior olive. In a similar manner, there was a 40% greater density of carbonic anhydrase-positive somata in the lateral limb compared to the medial limb. Transferrin immunostaining was restricted to oligodendrocytes, but the density of labeled somata was identical in the lateral and medial limbs. 2',3'-Cyclic nucleotide 3'-phosphodiesterase and myelin-associated glycoprotein were also localized to the somata of oligodendrocytes, labeling both perisomatic and interfascicular cells. At the ultrastructural level, specialized contacts were found between pairs or clusters of oligodendrocytes. These results suggest that more than one type of astrocyte and oligodendrocyte is present within the gerbil lateral superior olive. Furthermore, glial cells were unevenly distributed, such that a greater density of oligodendrocytes and fibrous-like astrocytes were found in the low-frequency projection region. This heterogeneity is well correlated with known differences in the neuronal morphology within the lateral superior olive

Effect of postsynaptic activity on the synaptic efficacy was studied in Xenopus nerve-muscle cultures. Repetitive postsynaptic depolarizations induced by injection of current pulses into singly innervated myocytes resulted in significant reduction in the frequency of spontaneous synaptic currents and the amplitude of nerve-evoked synaptic currents at the majority of synapses that showed immature synaptic properties. Repetitive hyperpolarizations and steady depolarizations of similar duration were without effect. The depolarization-induced synaptic depression appeared to result predominantly from a reduced ACh secretion from the presynaptic nerve terminal. Buffering the myocyte cytosolic Ca2+ at a low level with intracellular loading of a Ca2+ buffer, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid (BAPTA), significantly reduced the effect of the depolarizations. Thus postsynaptic electrical activity can regulate the synaptic efficacy of the developing neuromuscular synapases and the regulation may be mediated by retrograde transsynaptic interactions

The medial superior olive (MSO) functions as a coincidence detector for interaural time and phase differences by integrating excitatory synaptic inputs. Recent studies demonstrating glycinergic projections to MSO neurons suggest that coincidence detection results from the temporal integration of both EPSPs and IPSPs. We examined the impact of synaptic inhibition on the temporal coding properties of gerbil MSO neurons in vitro with intracellular recordings and electrical stimulation. For low-level bilateral electric stimulation, the EPSPs summated to produce an action potential in 73% of MSO neurons if they occurred within 50-500 microseconds of one another. Synaptic inhibition became more prominent at higher stimulus amplitudes in 73% of MSO neurons, and could block an evoked action potential if the stimuli to each pathway were delivered within 250 microseconds of one another. The glycine receptor antagonist strychnine influenced the response to simulated interaural time differences. In the presence of strychnine, interstimulus delays that originally resulted in full action potential suppression were sufficient to evoke an action potential. For trains of stimuli, as stimulus intensity increased (spatial summation), or as stimulus repetition rate increased to 100-500 Hz (temporal summation), there was a decrease in the number of stimulus pulses that evoked an action potential. In the presence of strychnine, MSO neurons generated a greater percentage of action potentials to the stimulus trains. When stimulus trains were delivered bilaterally, MSO neurons fired a greater number of action potentials at specific interstimulus time differences, and were selectively inhibited at other time differences.(ABSTRACT TRUNCATED AT 250 WORDS)

The structure of the submental platysma muscle was evaluated in 20 preserved cadavers. Four distinct patterns were identified, depending on the pattern of merging of the right and left platysma bundles. Fifteen percent of cases showed a complete platysma diaphragm submentally, while in the other 85% there was some degree of midline dehiscence. In the 85% of cases where right and left fibers merged or crossed to form a V or U shape, the apex of the V or U was measured relative to the chin point. The distance between right and left fibers was measured at two locations posterior to the chin point. The width of the midline dehiscence (when present) was 6-24 mm (mean 11.8 mm) 1 cm posterior to its apex and 10-44 mm (mean 20.00 mm) 2 cm posterior to the apex. The wider and more divergent the dehiscence and the more U-shaped the dehiscence between left and right platysma bundles, the greater may be the tendency to a 'turkey gobbler' deformity with inadequate medial support for the skin and subcutaneous tissues

Glomus jugulare tumors have been reported to secrete norepinephrine and cause severe hypertension with features similar to pheochromocytoma. In contrast, epinephrine secretion has not been observed in these neoplasms. This has been attributed to the absence of the norepinephrine-methylating enzyme, phenylethanolamine-N-methyltransferase (PNMT), required for epinephrine synthesis. We report a patient with severe hypertension caused by a glomus tumor that secreted norepinephrine and epinephrine. Following selective venous sampling, catecholamines were quantified by radioenzymatic assay. Marked elevations in norepinephrine and epinephrine release were localized to the glomus tumor. The enzymes involved in catecholamine biosynthesis, including PNMT and tyrosine hydroxylase, were identified immunocytochemically in the tumor. The glomus tumor had staining patterns identical to those observed within normal rat glomus cell. Hypertension resolved with resection of the functioning tumor. This is the first report of PNMT in a functioning paraganglioma of the glomus jugulare region. The factors that determine why functional activity is expressed only rarely by paraganglioma remain undefined.

BACKGROUND: Today's children will participate in a society whose economic basis will be information and communication and they must have optimal communication skills to be able to be functional optimally within the information society. Heretofore, in the United States, there has been no systematic attempt to diagnose and care for children with communication disorders. METHODS: It is essential that the child be diagnosed early because there appears to be a critical period for language development. CONCLUSION: If interventions do not occur early, in the area of communication disorders, there is a high probability of significant morbidity because of impaired communication abilities. This morbidity can manifest itself in a social activity and loss of economic opportunity.