Biomedical subjects
J Lehr
Publications and source records attributed to J Lehr.
Pulmonary surfactant as a vehicle for intratracheal delivery of technetium sulfur colloid and pentamidine in hamster lungs.
Tracheal instillation of pentamidine in a surfactant vehicle may be an effective direct method of antibiotic delivery to the lungs. In 10 healthy hamsters, we compared the pulmonary distribution of 99mTc sulfur colloid (TcSC) mixed with pentamidine, using as a vehicle either surfactant (n = 5) or saline (n = 5). Each animal was instilled with 0.25 ml/kg of suspension containing 0.0018 mCi TcSC and pentamidine mixed with either surfactant or saline. After 4 h of spontaneous respiration, the lungs were excised, inflated to TLC, dried, and sliced into 3-mm cross sections from apex to base. Autoradiographs were examined to evaluate 99mTc distribution. The surfactant group had detectable radioactivity in 93% of all slices compared with 72% in the saline group (p = 0.02). Six slices per animal (43% of total) and their corresponding autoradiographs were analyzed for distribution of radioactivity. Lung slice area was determined by planimetry, and autoradiograph area was determined by video densitometry. We calculated the fraction of each lung slice with detectable radioactivity. The surfactant group had 41% of the lung slice areas exposed compared with 21% in the saline group (p = 0.02). The coefficient of variation of radioactive intensities within each slice was used as an index of spatial uniformity. There was a trend towards more uniform distribution in the surfactant group, with a narrower range of variation of intensities (1.51 to 2.56) than the saline group (1.95 to 6.47). We conclude that a surfactant vehicle significantly increases airspace deposition of TcSC and pentamidine instilled intratracheally in normal hamster lungs, and may improve uniformity of spread.
In situ chromosome preparation technique for simultaneous cytogenetic and immunocytochemical studies on cell cultures of solid tumors.
Immunophenotyping of cultured cancer cells requires intact antigenic structures; these are mostly destroyed by conventional chromosome preparation techniques. Thus, the simultaneous cytogenetic and immunocytochemical characterization of solid tumor cells appears unfeasible. Here, we describe a novel method that allows in situ chromosome preparation from monolayer cultures of solid tumor cells without affecting their immunological features. Using this technique, it is possible to achieve detailed cytogenetic data including chromosome banding together with the demonstration of cytoplasmic and nuclear antigens within the same tumor cells.
Mechanics of the respiratory system during high frequency ventilation.
No rational approach has evolved for selecting operating conditions for clinical application of high-frequency ventilation (HFV). To this end, we divide our discussion of HFV into considerations of mechanics versus transport, and treat the latter as a constraint. After describing some of the phenomena that influence distending pressure (and its distribution) expressed across pulmonary tissues, we address the pressure costs per unit ventilation and the factors that influence them. This narrowly defined approach leads to some fundamental strategies, compromises, and dilemmas. In particular, consideration of the mechanical interaction of the lung and chest wall leads to a paradox, and points out that the influence of the chest wall upon phasic regional lung distension is not well understood.
Functional characterization of cells isolated from the pancreas of non-obese diabetic mice.
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Pulmonary afferent activity during high-frequency ventilation at constant mean lung volume.
We recorded the responses of 21 slowly adapting pulmonary stretch receptors (PSRs) and 8 rapidly adapting pulmonary stretch receptors (RARs) from the vagi of anesthetized open-chest dogs to high-frequency ventilation (HFV) at 15 Hz, at constant mean end-expiratory lung volume, and constant end-tidal PCO2. HFV applied in this way has been shown to prolong expiration. The responses of pulmonary afferents during HFV at constant mean volume have not been described. In the present experiments, receptor discharge during HFV was compared with that during the end-expiratory pause of normal-frequency ventilation. Average PSR discharge increased when HFV was applied, although not all PSRs exhibited increases. RARs were generally silent during normal and high-frequency ventilation at functional residual capacity and above. However, at low lung volumes, RAR discharge increased greatly when HFV was applied. We conclude that PSR discharge is increased during HFV in the absence of increased lung volume and that increases in PSR discharge during HFV are sufficient to explain the reflex that prolongs expiration in dogs.
High frequency oscillation of the lungs alone lengthens expiration in dogs.
High frequency (15 Hz), low volume (approximately 40 ml) oscillation of the respiratory system lengthens expiration in anesthetized dogs even in the absence of changes in mean expiratory lung volume or blood gases (Banzett et al., 1983). Although vagotomy abolishes this response, we felt it might mask the reflex rather than interrupt the afferent pathway. To ascertain whether pulmonary and airway afferents alone are capable of evoking this reflex, we confined the oscillatory stimulus to the lung by widely opening the chest. The dogs were paralyzed but breathed 'spontaneously' by means of a solenoid valve opened and closed by the phrenic neurogram. End-expiratory lung volume and PCO2 were held constant. All eight dogs that were tested after thoracotomy lengthened expiration during oscillation. Although quantitative comparisons of responses before and after thoracotomy are not entirely reliable, we could see no consistent change in the strength of response with paralysis or with thoracotomy. We conclude that the principal afferent limb of the ventilatory reflex response to oscillation arises in the lungs and intrathoracic airways.
A vector derivation useful in impedance plethysmographic field calculations.
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[Relations between the contamination of beef and cow's milk with radiocesium].
The paper presents the results of an experimental investigation designed to study the trend of the contamination by radiocesium of milk and meat of cows: (1) under conditions of a single contamination of the pasture. (2) under conditions of a continuous ingestion corresponding to the case of a constant contamination of the pasture. The knowledge of the evolution in the course of time of the relation between the activities of meat and milk and of its dependence on the nature of the different organs and the age of the animals should make more easy the survey of the contamination of the environment and allow to decide on possible countermeasures to be taken in the case of an accident.