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Hemolysis tests with fresh human blood were performed in vitro with a new 5 ml, piston-type hemoperfusion pump, designed to prevent myocardial ischemia during coronary angioplasty. Despite driving pressures greater than 3 atmospheres, shear stress greater than 200 Pa, turbulent pump flow, and the presence of occlusive valves, hemolysis proved to be minimal. This effect is explained by the short amount of time that blood is subjected to mechanical forces that cause hemolysis in the system and by the small volumes of blood involved. During clinical application of the system, angina pectoris, electrocardiographic changes, and systemic blood pressure were used as parameters for myocardial ischemia. There was an effective reduction of ischemia during prolonged (10 min) balloon inflation, demonstrated by the absence of angina, minimal electrocardiographic changes, and normal blood pressure. In addition, the system proved to be safe and effective during high-risk angioplasty.

• Fifty-four elderly patients with thermoregulatory failure were evaluated retrospectively. The most commonly associated cause was underlying sepsis, which occurred in 78% of cases. Underlying conditions that increased the incidence of hypothermia were hypoproteinemia (50%), cachexia (30%), and neuroleptic medications (21 %), most commonly thioridazine. Digoxin toxicity was a common finding (20% of all cases). One third of the patients developed hypothermia in warm months and half of them developed it while in the hospital. Patients who presented with hypothermia from out of the hospital had lower temperatures, were more bradycardic and hemoconcentrated, and died more rapidly than the in-hospital group. This could be explained by lower outside temperature or delay in diagnosis and treatment of the underlying disease. The overall mortality rate was extremely high (74%) in both groups. The mortality rate was not affected by age, sex, or degree of hypothermia. We conclude that thermoregulatory failure in the elderly can occur in warm as well as cold environments or climates. The development of hypothermia in elderly patients should be promptly treated as sepsis unless proven otherwise, in light of the poor prognosis of this condition. ( Arch Intern Med . 1989;149:1521-1523)

The basic nature of pitch is much debated. A robust code for pitch exists in the auditory nerve in the form of an across-fiber pooled interspike interval (ISI) distribution, which resembles the stimulus autocorrelation. An unsolved question is how this representation can be "read out" by the brain. A new view is proposed in which a known brain-stem property plays a key role in the coding of periodicity, which I refer to as "entracking", a contraction of "entrained phase-locking". It is proposed that a scalar rather than vector code of periodicity exists by virtue of coincidence detectors that code the dominant ISI directly into spike rate through entracking. Perfect entracking means that a neuron fires one spike per stimulus-waveform repetition period, so that firing rate equals the repetition frequency. Key properties are invariance with SPL and generalization across stimuli. The main limitation in this code is the upper limit of firing (~ 500 Hz). It is proposed that entracking provides a periodicity tag which is superimposed on a tonotopic analysis: at low SPLs and fundamental frequencies > 500 Hz, a spectral or place mechanism codes for pitch. With increasing SPL the place code degrades but entracking improves and first occurs in neurons with low thresholds for the spectral components present. The prediction is that populations of entracking neurons, extended across characteristic frequency, form plateaus ("buttes") of firing rate tied to periodicity. ispartof: PHYSIOLOGY, PSYCHOACOUSTICS AND COGNITION IN NORMAL AND IMPAIRED HEARING vol:894 pages:347-354 ispartof: location:United States status: published