Poromas of the head and neck.

BACKGROUND: The "eccrine" poroma is a benign neoplasm previously thought to originate from the eccrine sweat gland. Early studies suggested that these were primarily lesions of the hairless acral surfaces. OBJECTIVE: This article reports the clinical and histologic findings of 10 cases of poroma of the head and neck area. METHODS: The clinical and histologic findings of 10 cases of poroma of the head and neck area are compared with 10 poromas occurring on the extremities. RESULTS: Some poromas demonstrated evidence for apocrine origin. Unlike poromas found on the extremities, head and neck poromas were usually asymptomatic and were never correctly diagnosed clinically. Although 9 of 10 poromas on the extremities occurred in male patients, the head and neck poromas showed no gender predilection. CONCLUSION: Clinicians should be aware that poromas can occur in the head and neck area and may be of apocrine origin.

Nephrotic syndrome associated with a clonal T-cell leukemia of large granular lymphocytes with cytotoxic function.

A 51-year-old man presented with a T-cell leukemia of large granular lymphocytes and rapidly developed a nephrotic syndrome due to presumptive minimal-change glomerulopathy. The E-rosette+, Ia+ cells demonstrated cytotoxic activity similar to that of natural killer lymphocytes but lacked other T-subset markers, except that one third of them bore Fc(IgG) receptors. Cytogenetic analysis revealed loss of chromosome 10 and the translocation (1;10)(p11;q11) in all metaphases. Regression of the leukemia after chemotherapy was accompanied by a dramatic resolution of the nephrotic syndrome, suggesting that the activated granular lymphocytes induced the renal lesion. The close association of a clonal T-lymphoproliferative disorder with minimal-change nephrotic syndrome lends further support to current views implicating activated T cells or their products in the pathogenesis of this glomerulopathy.

Guinea pig tectorial membrane profile in an in vitro cochlear preparation.

The guinea pig cochlea was examined under high-magnification light microscopy in an in vitro preparation. After extraction of the otic capsule, the bulla was opened widely and a small hole made into the fourth turn of the scala vestibuli. The organ of Corti was visualized under artificial endolymph at 600 X magnification. Added 1-micron titanium dioxide particles settled on the upper surface of the transparent tectorial membrane. Particle positions showed that much of this upper surface lay in a flat sheet that extended centrifugally almost to the Hensen's cells, giving the impression it was attached there. The sheet extended at least to the level of the inner hair cells, where a tectorial membrane thickness of about 40 micron was reached. Titanium dioxide particles were seen regularly in immediate proximity to the hair cell cilia, indicating that scala media is continuous with the subtectorial space. Upon mechanical manipulation, Hensen's cells proved to be extremely cohesive and elastic. It is suggested that hair cell stereocilia provide major mechanical connections for the tectorial membrane.

Neurons in the cat's primary auditory cortex distinguished by their responses to tones and wide-spectrum noise.

In the cortex of barbiturate-anesthetized cats, area AI was identified by its tonotopic organization, and single neurons in that field were examined with regard to the shapes of their spike count-versus-intensity functions, the organization of their frequency-intensity response areas, and their responses to wide-spectrum noise, using calibrated sealed stimulating systems. Neurons whose pure tone rate intensity functions were monotonic in shape displayed V-shaped response areas that were open-ended at high tone intensities. In contrast, cells displaying nonmonotonic tone intensity functions tended to have circumscribed response areas; these cells were responsive to tones over limited ranges of both frequency and intensity. Monotonic neurons almost always responded to wide-spectrum noise stimuli, while nonmonotonic neurons often did not. The mean minimum latent period of monotonic cells (14.0 ms) was significantly shorter than that for nonmonotonic neurons (19.1 ms). For those cells that responded to both tones and noise, minimum latent periods for the two stimuli were similar or identical. Monotonic neurons tended to be horizontally segregated from nonmonotonic neurons across AI's middle cortical layers. The implications of these data for the nature of some neural mechanisms underlying the stimulus selectivity of cortical cells are discussed.

Binaural interactions in cortical area AI of cats reared with unilateral atresia of the external ear canal.

Binaural interactions were recorded in auditory cortical (AI) neurons of anesthetized adult cats that had unilateral atresias created shortly after birth by surgically ligating and cutting one external ear canal. At the time of the recording experiment, the atresia and associated debris were removed and tones were delivered to both tympanic membranes via a sealed and calibrated acoustic system. The majority of neurons recorded were in the cortex ipsilateral to the previously occluded ear. Thresholds for monaural stimulation of either the operated or unoperated ear were within normal range although thresholds to stimulation of the previously operated ear tended to occupy the upper end of the normal distribution. Monotonic and nonmonotonic spike count-vs-intensity functions derived from responses to monaural stimulation of the atretic ear were indistinguishable in their shape from those recorded in normal cats. All binaural classes were represented in our sample in proportions similar to those reported in cats with two normal ears. The forms of the functions relating spike count to interaural intensity differences and interaural phase differences were essentially the same as those seen in normal animals. The main binaural deficit observed under these conditions was a shift in the interaural intensity difference to which an AI neuron was most sensitive. The intensity needed for a stimulus to the atretic ear to participate in the binaural response was as much as 50 dB higher than that at the opposite normal ear in contrast to the nearly equal SPLs required for binaural interactions in cats with two ears intact. It was suggested that elevated thresholds at the previously operated ear could account for much of the shift observed.

Binaural interactions of single neurons in posterior field of cat auditory cortex.

In the auditory cortex of barbiturate-anesthetized cats, the posterior auditory field (area P) was identified by its tonotopic organization, and single neurons in that field were studied quantitatively with regard to their binaural interactions at their respective best frequencies, using calibrated, sealed stimulating systems. Almost 60% of the neurons studied displayed " summative " binaural interactions in that their responses to binaural, equally intense stimulation of the two ears were stronger than were their responses to monaural stimuli of the same intensity. For these neurons, latent periods were shorter for binaural stimuli than for monaural stimuli. Some field P neurons were sensitive to interaural intensity disparities and manifested that sensitivity in one of two forms. Cells that were excited by stimulation of one ear and inhibited by stimulation of the other typically displayed a sigmoidal relation of spike count to intensive disparity, with spike counts being larger when the disparity favored the contralateral ear. Cells that were unresponsive to monaural stimuli but responded securely to binaural stimuli usually displayed a peaked, nonmonotonic relation of spike count to interaural intensity disparity, with maximal responses being elicited by stimuli with zero or near-zero disparity. Some neurons of low best frequency were sensitive to variations in interaural phase delay. In all cases, this sensitivity was manifested as a cyclical relation of spike count to interaural delay, with the period of the cycle being that of the stimulating tone. The fact that the binaural interactions of field P neurons were similar to those of cells in the primary auditory cortex suggests that the previously described heightened spectral-amplitude selectivity of field P neurons has been achieved without cost to their sensitivity to a variety of parameters of binaural stimulation. The particular sensitivity of cortical neurons to variations in interaural disparities associated with midline or near-midline azimuths might constitute a neural mechanism for the behavioral finding that animals and humans show their greatest acuity in sound localization for stimulus locations in or near the midsagittal plane.

Evolution to eosinophilic leukemia with a t(5:11) translocation in a patient with idiopathic hypereosinophilic syndrome.

The idiopathic hypereosinophilic syndrome (HES) comprises a diverse group of diseases that may ultimately lead to multiorgan dysfunction and death. We present a case of a man who was followed for over 9 years with HES that underwent malignant transformation to acute leukemia with eosinophilic features. The patient's clinical acceleration was accompanied by the development of a malignant clone that was identified with banding techniques as 46,XY,t(5:11)(p15;q13). Electron microscopy reaffirmed findings reported in earlier cases of eosinophilic leukemia. At no time during his illness were cytotoxic drugs administered. In addition to delineating the natural evolution and cytostructural details of the case, we emphasize the role of cytogenetics in the predicting of malignant variants of the hypereosinophilic syndrome and in identifying eosinophilic leukemia.

Sensory hairs as mechanical filters in crista ampullaris: passive through structure and active through contraction.

The present text is a summary of original work describing individual variation in mechanical filter properties between different sensory hair bundles in the frog crista ampullaris. The difference relies on a variation of the degree of development of stereocilia within each bundle. Active control of mechanical properties is implied by the finding that media that would induce contraction in a muscle cell cause a restriction of motility of the sensory hairs.

Responses of single neurons in posterior field of cat auditory cortex to tonal stimulation.

In the auditory cortex of barbiturate-anesthetized cats, the posterior auditory field (field P) was identified by its tonotopic organization, and single neurons in that field were studied quantitatively for their sensitivity to the frequency and intensity of tonal stimuli presented via calibrated, sealed stimulating systems. Field P neurons had narrow, V-shaped, threshold frequency tuning curves. At suprathreshold levels, spike counts were generally greatest at frequencies at or close to the neuron's threshold best frequency (BF). Eighty-six percent of posterior-field neurons displayed spike counts that were a nonmonotonic function of the intensity of a BF tone. Of these, over 90% showed at least a 50% reduction in spike count at high stimulus levels, and almost 20% of nonmonotonic cells ceased responding entirely at high stimulus intensities. The nonmonotonic shape of spike count-versus-intensity profiles was typically preserved across the range of frequencies to which any given neuron was responsive. For some neurons, this had the consequence of generating a completely circumscribed frequency-intensity response area. That is, these neurons responded to a tonal stimulus only if the stimulus was within a restricted range of both frequency and intensity. These response areas showed internal organizations that appeared to reflect one or both of two processes. For some neurons, the optimal sound pressure level for spike counts varied with tone frequency, roughly paralleling the threshold tuning curve. For other neurons, the optimal sound pressure level tended to be constant across frequency despite threshold variations of up to 20 dB. The minimum response latencies of posterior-field neurons were generally in the range of 20-50 ms, while cells in the primary auditory cortex (AI) in the same animals generally had minimum latent periods of less than 20 ms. Comparison of these data with those previously presented for neurons in two other cortical auditory fields suggests that the cat's auditory cortex might show an interfield segregation of neurons according to their coding properties.

Active control of sensory hair mechanics implied by susceptibility to media that induce contraction in muscle.

The motion of individual sensory hair bundles in the crista ampullaris was studied quantitatively by subjecting them to a brief jet of fluid in response to which they would swing away and then return by elasticity inherent at their insertion point. This motion was studied in media that would induce relaxation or contraction in a muscle system. The motion became severely restricted under conditions promoting contraction. Similar results were obtained by application to the organ of an ionophore that has the capacity to enter the cell membrane and allow influx of calcium ions. There was no effect of the ionophore in the absence of calcium ions. These results indicate that the sensory cells in the ear may possess a contractile machinery situated at the input end of the cell in the region of the sensory hairs and cuticular plate. The functional implication is that the mechanical input properties of the hair cells, and thus their excitability, can be under physiological control. It further implies that hair cells can produce a mechanical output in response to sensory or synaptic stimuli.

Micromechanical properties of sensory hairs on receptor cells of the inner ear.

The aim of the investigation was to obtain quantitative measures of mechanical filter properties of hair cell sensory hairs which were not restricted to move by auxiliary structures. The specimen used was the crista ampullaris of the frog, dissected free and positioned in a fluid-filled chamber where it could be viewed with differential interference contrast optics. The sensory hairs were displaced by a brief jet of frog Ringer's solution from a specially constructed microsyringe apparatus. The velocity of the jet could be stepwise controlled and was determined by measuring the speed of motion of 3 micron plastic beads propelled with the jet across the microscopic field. The stereocilia displacements were recorded on 16 min film, and both the angle of deflection and the time for the return to the resting position were measured on the film. It was found that after displacement the sensory hairs returned to the upright position by elastic properties in the hinge region at their insertion point in the cuticular plate. Sensory hairs differed in their speed of return so that some had fast time constants, others quite slow ones. This was correlated to a difference in structural development of the stereocilia, fast sensory hairs having thick and tall stereocilia, slow ones having thin and short stereocilia. The various bundle types were identified in the scanning electron microscope and their distribution on the crista was mapped. This was found to match the distribution of nerve fibres with different functional properties. It is concluded that sensory hair cells can differ in their mechanical filter properties as a result of the structural arrangement of their stereocilia and in accordance with functional demands.

Effects of changes in cortical arousal and of auditory cortex cooling on neuronal activity in the medial geniculate body.

The activity of cells in the medial geniculate body (MGB) of adult cats was recorded during different states of cortical arousal with and without cooling of the auditory cortex. In the absence of auditory cortex cooling, the overall mean unit spontaneous discharge rate was 49% higher during desynchroized Electrocorticogram (ECoG) periods (high cortical arousal). Responses to sound were somewhat more prominent vis-à-vis the spontaneous activity during periods of high arousal. Changes in spontaneous discharge rate associated with arousal shifts were significantly reduced during auditory cortex cooling. When the ECoG changed from desynchronized to synchronized activity, MGB cells showed a change in discharge pattern, typically characterized by an increase in both high-rate bursts and long-interval pauses. These changes were duplicated for most cells by cooling of the auditory cortex. Corticofugal fiber discharge thus has an effect on MGB neuronal activity which is dependent on the level of cortical arousal. This effect is most likely a result of direct corticogeniculate activity, though indirect auditory cortex - brainstem - MGB routes may also be involved.

Removable, conforming device for cooling the cortical surface.

A technique for cooling the cerebral cortex is described. It makes use of a neoprene bladder through which cold fluids is circulated. The flexible bladder is contained within a cylinder permanently attached to the skull. The bladder itself can be quickly installed and removed and conforms to the cortical surface with minimal pressure.