"Orbiting the orbicularis"--restoration of muscle-ring continuity with myocutaneous flaps

Eyelid repair by the Mustardé cheek flap or the Hughes tarsoconjunctival lid-sharing flap have been methods deservingly popular with plastic surgeons for many years. Recent attention given to the myocutaneous flap principle has prompted the formulation of a new approach to this difficult problem of replacing an eyelid. In these cases, we have taken what most plastic surgeons are currently "throwing away" in their blepharoplasties and used it to reconstruct up to an entire margin of the eyelid. This new method seems simple because it holds the promise of fewer procedures and perhaps more functional results.

Single-unit activity in the auditory cortex of monkeys actively localizing sound sources: spatial tuning and behavioral dependency

Single-unit recordings were made from the auditory cortex of unanesthetized rhesus monkeys which were trained to perform a second localization task. Recordings were made from 196 units in 4 animals. Five sound sources were located at 0 degrees (midline) and on either side at azimuths of 37.5 degrees and 75 degrees. Almost most units responded to each of the 5 sources, 49% of the units had peak firing rates for the source on the contralateral side at 75% azimuth. Another 26% of the units had peak firing rates at the 37.5 degrees contralateral location, while only 11% had peak rates for the ipsilateral locations. In order to determine whether the behavior of actively locating a sound source affected units in auditory cortex, response rates compared under two behavioral conditions: one which required the detection of a sound regardless of location and another condition which required identification of a sound's location. of the 196 units, 16 had different response rates for the two conditions, with 15 of the 16 units having higher evoked rates in the localization task. For the 16 units, the difference in firing rate was typically observed for a single speaker location. No correlation could be determined between a unit's location within the subdivisions of auditory cortex and its spatial tuning response properties or its dependency upon behavioral condition.

Cupula motion in the semicircular canal of the skate, Raja erinacea. An experimental investigation

An upper bound on the magnitude of semicurcular canal cupula motion was experimentally determined in the isolated labyrinth of the skate, Raja erinacea. To visualize the cupula, a glass pipette was pushed through the ampullary wall, and local regions of the cupula were stained by slow infusion of small amounts of Alcian Blue dye. Caloric stimuli which produced large changes in single unit activity in the ampullary nerve and which often recruited several larger, previously silent units were found to produce on detectable cupula motion as seen through the ampulla wall. However when the cupula was first grossly displaced, motion was thereafter observed in response to identical caloric stimuli. Analysis of afferent responses indicates that the normal range of cupula motion in the skate is below the optical resolution of the method, conservatively estimated as 3--5 micrometers.

Cupular movement and nerve impulse response in the isolated semicircular canal

The aim of the study was to record nerve impulse responses to controlled displacements of the cupula and relate these to observations of cupular motion. The preparation was the skate semicircular canal, isolated and maintained in a chamber. The canal was cut and tied tightly to an oil-filled tube driven by a 1 microliter syringe. In some experiments dye was used to make the face of the cupula visible. Small volume displacements (0.02 microliter) caused a billowing of the central portion of the cupula, whereas for repeated large displacements (0.1 microliter) the top of the cupula moved along the roof of the ampulla. Displacements of the latter amount were close to saturation in the characteristic functions (spike rate versus volume displacement) of nerve firing. It seems that the discharge rate of tonically responding units in the skate crista ampullaris rather faithfully record the force acting on the cupula. The motion of the base of the cupula rather than its tip appears to be the relevant parameter in setting the level of excitation in the sensory cells within the physiological range of stimulation. Such a mode of operation would ensure the highest sensitivity of the sense organ.

Effect of chronic furosemide administration on hydrogen and sodium excretion in the dog

Studies were performed to evaluate the effects of the chronic administration of furosemide on hydrogen and electrolyte excretion in dogs on a normal electrolyte diet and in the absence of electrolyte or volume depletion. Control daily excretion in five dogs averaged 64 meq for Na, 51 meq for K, 66 meq for Cl, and 17 meq for net H. Furosemide, 40 mg, in the drinking water 3 times daily was given for 4 days. On day 1 Na excretion averaged 128 meq, but thereafter was not significantly different from control levels. Over 4 days cumulative net H excretion increased 63.6 meq and plasma HCO3 rose 6.6 meq/liter. The same dogs were restudied by the same protocol except that, to obviate electrolyte depletion, NaCl and KCl were administered daily in quantities sufficient to replace urinary losses. All dogs remained in positive Na, K, and Cl balance. Body weight, hematocrit, plasma albumin, creatinine, and plasma renin activity were unchanged, indicating the absence of electrolyte or volume depletion. Nonetheless, cumulative net H excretion increased 61.2 meq and plasma HCO3 increased 4.3 meq/liter. Two adrenalectomized dogs receiving steroid replacement showed similar changes in net H excretion and plasma HCO3. These experiments suggest that chronic furosemide administration may enhance H excretion and generate alkalosis even in the absence of volume or electrolyte depletion and without increased aldosterone secretion.

Evoked unit activity in auditory cortex of monkeys performing a selective attention task

Single-unit responses were recorded from the auditory cortex of rhesus monkeys performing a selective atteintion task which used combined light and sound stimuli. The animals were first trained to push a lever to the left for a noise burst and to the right for a tone burst, and then trained to push left for a left light and right for a right light. Subsequently, one of the four possible light and sound stimulus combinations (Noise + Left Light, Noise + Right Light, Tone + Left Light, Tone + Right Light) was randomly presented on each trial. In blocks of 100 trials only one part of the combined stimulus (either the light or the sound) determined the direction of lever push that would be reinforced. Responses of single units to identical sound stimuli were compared for blocks in which sound was the relevant cue and blocks in which light was the relevant cue. Typically, differences were in response strength without alteration of response pattern. Even the earliest response components (15-20 msec latency) could show changes. Two-thirds of the response comparisons showed differences in strength depending upon whether sound or light was the relevant cue, with about as many responses stronger for light relevant as for sound relevant. Independent of which modality was relevant, unit responses for trials in which both parts of the combined light and sound stimulus indicated the same direction of lever push were generally stronger than unit responses for trials in which the two parts of the combined stimulus signalled opposite directions of lever pushes.

Treatment of idiopathic membranous nephropathy

In a retrospective study of the effect of treatment in biopsy-proved idiopathic membranous nephropathy, 91 adults and 12 children were followed for periods up to 29 years after clinical onset (mean, 6.5 years). Forty-four were treated with corticosteroids, 15 with corticosteroids and immunosuppressants; 44 had no treatment and served as a control group. Clinical cure and improvement were significantly greater in the treated than in the nontreated group (P less than 0.01). The recurrence rate, occurrence of renal failure and probability of death were significantly greater in the nontreated group, although some of these patients eventually showed improvement. Prognosis was better in patients who responded to therapy. These data strongly suggest that steroid therapy is beneficial in patients with membranous nephropathy.

Effect of sodium nitrate loading on electrolyte transport by the renal tubule

Effects of sodium nitrate were compared with sodium chloride loading on transport of electrolytes by the nephron. Maximal levels of free water clearance/clomerular filtration rate (CH2O/GFR) averaged 8.4% with nitrate loading and 14.4% with saline loading. Since ethacrynic acid and chlorothiazide exert their major natriuretic effect in the distal nephron, the increment in Na ad Cl reabsorbed beyond the proximal tubule. The administration of these agents resulted in an increase in fractional sodium excretion (CNa/GFR) of 21.1%, urinary sodium excretion (UNaV) of 1,126 mueq/min, and urinary chloride excretion (UClV) of 848 mueq/min during nitrate loading compared with an increase in CNa/GFR of 37.6%, UNaV of 2,362 mueq/min, and UClV of 2,397 mueq/min during saline loading. The smaller diuretic-induced increment in Na and Cl excretion in the nitrate studies suggests, as do the hydrated studies, that less Cl and Na are reabsorbed in the distal nephron during nitrate than saline loading. At every level of UNaV, fractional bicarbonate reabsorption was higher, urine pH was lower, and urinary potassium excretion (UKV) was higher in the nitrate studies. Thus, compared with saline loading, sodium nitrate decreases chloride and sodium reabsorption in the distal nephron. The higher hydrogen and potassium secretion in the nitrate studies may be consequent to the decreased ability of the distal nephron to reabsorb chloride.