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Our laboratory has been comparing the activity of a water extract of cotton bract (CBE) with the isolated trachealis smooth muscle of the dog, guinea pig, and cat. CBE induced contractions that were not mediated by 5-hydroxytryptamine (5-HT), histamine, or muscarinic receptors. The active agent(s) in CBE was dialyzable (less than 14,000 molecular weight), and substantial activity was retained after low-temperature ashing. CBE potentiated contractions of dog trachealis to histamine and 5-HT and relaxation responses to isoproterenol, whereas it had no effect on responses to methacholine and KCl. In the guinea pig trachealis, CBE reduced responsiveness to KCl, potentiated relaxations to adenosine and ATP, and did not alter the responses to the remaining agents. Responses of cat trachealis to KCl and isoproterenol were potentiated by CBE, while those to 5-HT were unaffected. Neurogenic cholinergic contractile responses were potentiated by CBE in the trachealis of the dog, but not of the guinea pig, while neurogenic relaxations were potentiated by CBE in guinea pig trachealis but not in the dog trachealis. There are thus marked species differences in the acute effects of CBE on airway smooth muscle. Due to recent interest in the possible involvement of bacterial endotoxins in the etiology of byssinosis, we examined the effects of E. coli lipopolysaccharide (LPS) in guinea pig trachealis. An initial examination revealed that LPS potentiated responses to histamine, but not those to methacholine and isoproterenol. This effect vanished upon a second appraisal with a different batch of LPS. The effect of LPS in airway smooth muscle is thus, at present, equivocal.

The effects of a water extract of cotton bracts (CBE) on guinea pig isolated trachealis smooth muscle was studied. The ability of CBE to evoke tension responses, to modify tissue reactivity to excitatory and inhibitory agents, and to modify electric field stimulation-induced neurogenic responses was evaluated. CBE caused contraction in low concentrations, which were not mediated by histamine H1-, muscarinic, or 5-hydroxytryptamine (5-HT) receptors, and caused relaxation in high concentrations. In the presence of CBE, the maximum contractile response to 5-HT and the sensitivity to KCl were reduced. The maximum relaxation responses and sensitivities to adenosine and ATP were increased by CBE. In contrast, contractile responses to histamine and methacholine and relaxation responses to isoproterenol were unaffected. Neurogenic cholinergic excitatory responses and neurogenic adrenergic responses did not appear to be affected by CBE. However, the relaxant effect of nonadrenergic inhibitory nerve stimulation was increased in the presence of CBE. These findings differ from previous ones observed in our laboratory for dog isolated trachealis smooth muscle preparations, which indicates that the effects of CBE in isolated airways is species-dependent. Virtually all of the contractile activity of CBE was dialyzable (molecular weight less than 14,000) and retained in ashed samples. Inorganic constituents may contribute to the spasmogenic activity of CBE.

The inhalation of cotton dust by cotton-mill workers causes byssinosis, a disease characterized by chest tightness and other symptoms indicative of bronchoconstriction. In the present study the dog isolated trachealis smooth muscle preparation was employed to examine the ability of a crude, water extract of cotton bracts (CBE) to (1) cause contractile responses mediated by receptors, (2) modify responses of the tissue to a number of excitatory and inhibitory agents, and (3) alter responsiveness of the preparations to electrical field stimulation mediated by intrinsic cholinergic, excitatory nerves and adrenergic, inhibitory nerves. CBE evoked contraction of the tissues by an action that did not involve muscarinic, histamine, or 5-hydroxytryptamine receptors. The maximum tissue responses to exogenous histamine, 5-hydroxytryptamine, and isoproterenol were enhanced significantly in the presence of CBE, while those to KCl and methacholine were unaffected. The sensitivities (EC50 values) of the tissues to these agents were not, however, altered by CBE. Contractions induced by cholinergic nerve stimulation were increased in the presence of CBE, via a mechanism that appears, at present, to result from a prejunctional facilitation of acetycholine release. Relaxations to adrenergic nerve stimulation were not affected by CBE. Results suggest that, in addition to its direct, contractile activity, CBE can alter indirectly the responsiveness of the tissue to a number of endogenous mediator substances. Intrinsic, cholinergic excitatory nerves may be a target for the acute action of CBE as well.

Summary and ConclusionIn 13 trials in 9 dogs, when the intact tibias were perfused by way of the femoral artery with blood and cardio-green dye at a constant rate (set to maintain equivalent blood pressure), the average pulsatile OD activity was 0.21 ± 0.03% and 0.15 ± 0.04%, respectively, when compared to the total OD change seen with the perfusion of the bone with saline. These results indicate that the majority of the pulsatile activity was due to volume changes within the bones' vascular system and not due to flow-related phenomena. When in six dogs, 24 injections of acetylcholine (60–90 μg) and 26 injections of norepinephrine (8–10 μg) were made into the femoral artery under constant flow conditions, the mean maximum total OD decreased 16% and 18%, respectively. These changes were most probably due to changes in the bone vascular volume.The authors wish to thank Miss Paula Phillips, Mr. James Bland, and Miss Sandra Hershberger for their fine technical assistance.

Cats were anesthetized and placed, with the chest opened, inside a whole-body plethysmograph. In recording gas and liquid pressure-volume (PV) curves, 100 percent oxygen (2.9 ml/sec) and Ringer-Locke solution (1 ml/sec) were used. Gas and liquid flows were varied from 2.9–6.0 ml/sec and 0.5–5.0 ml/sec respectively, with no change in either the hysteresis or the shape of the PV curve. A constant, K, was determined by comparing the gas and liquid inflation curves at maximal lung volumes and using the equation K = 3PV case1 2 γ, where γ was assumed to be 50 dyne/cm. The mean value for K in eight experiments was 1225 ± 100 Sem. At a functional residual capacity of 90 ml the alveolar surface area (A = KV 2 3 ) of the cat/kg body mass was 1.05 ± 0.09 m2. Surface tension was calculated during inflation and deflation. The results indicate that surface tension approaches zero at low lung volumes or areas and is always lower during deflation than during inflation at a given volume or area.

Quantitative spinal cord (SC) magnetic resonance imaging (MRI) presents many challenges, including a lack of standardized imaging protocols. Here we present a prospectively harmonized quantitative MRI protocol, which we refer to as the spine generic protocol, for users of 3T MRI systems from the three main manufacturers: GE, Philips and Siemens. The protocol provides guidance for assessing SC macrostructural and microstructural integrity: T1-weighted and T2-weighted imaging for SC cross-sectional area computation, multi-echo gradient echo for gray matter cross-sectional area, and magnetization transfer and diffusion weighted imaging for assessing white matter microstructure. In a companion paper from the same authors, the spine generic protocol was used to acquire data across 42 centers in 260 healthy subjects. The key details of the spine generic protocol are also available in an open-access document that can be found at https://github.com/spine-generic/protocols . The protocol will serve as a starting point for researchers and clinicians implementing new SC imaging initiatives so that, in the future, inclusion of the SC in neuroimaging protocols will be more common. The protocol could be implemented by any trained MR technician or by a researcher/clinician familiar with MRI acquisition.

Dipalmitoyl lecithin adsorbs from micellar dispersion in brine onto respirable sized kaolin particles. In the concentration range of 1 to 10 n M /μl and at 37°C, one gram of kaolin adsorbs about 0.18 grams of lecithin, and at 21°C the dominant characteristic time of the double exponential adsorption is 0.54 hours. When compared with values for the amount of pulmonary surfactant in man and its normal replacement rate, dust doses which might produce an in vivo deficit can be predicted. Several functions in the pulmonary surfactant system which have not been quantified would determine the duration and localization of the deficit.

The effects of kaolin and flyash on synthetic dipalmitoyl lecithin and lung surfactant from the lavage of excised rat lungs were studied using a Wilhelmy-type surface balance. After control studies with dipalmitoyl lecithin and rat lung surfactant, particles were sprinkled onto the surface at minimum surface area and the surface tensions vs surface areas were recorded. The results showed increased minimum surface tensions and decreased hysteresis areas when the particles were added. More particles were required to change the hysteresis area of lung surfactant than were required for synthetic dipalmitoyl lecithin. The effects of changes in surface areas of alumina and zinc oxide particles on dipalmitoyl lecithin were also studied. The amount of particles required to reduce surface tension-surface area hysteresis increased as the particles' surface area per gram decreased. This study indicates that respirable dusts may adsorb dipalmitoyl lecithin or lung surfactant in vivo and, therefore, may prevent surface tension from reaching the low values generally thought to occur in vivo.

Excised rat lungs were ventilated with air in a liquid filled plethysmograph that was enclosed in a large pressure chamber, C(B). The lungs were inflated then deflated by removing or adding saline to the plethysmograph while the trachea was attached to a cannula extending through the plethysmograph base. In this system, tracheal pressure, Pao, was equal to gas pressure inside C(B). The gas pressure was held constant at either ambient pressure (Pamb), Pamb + 350 Torr, or Pamb - 350 Torr. When excised lungs were ventilated slowly from their atelectatic state for 10 inflation-deflation cycles with Pao equal to any one of the three pressures, an equivalent amount of gas was trapped in the lungs. If after 10 cycles, however, lungs containing trapped gas were inflated and held at maximum lung volume, the trapped gas spaces could be made to expand in response to rarefaction or compression of the tracheal gas. The amount of expansion and contraction of the trapped gas spaces demonstrates that trapped gas is likely trapped between menisci of a foam that occlude the alveoli or small airways.

Rat lungs were ventilated in a saline filled plethysmograph with the trachea attached to a cannula extending through the chamber base. Because it was possible to conect the cannula to an anesthesia bag, the gases used to ventilate the lungs could easily be controlled. During the first part of the study, lungs were inflated-deflated at different rates for 10 cycles with one of four different gases (SF 6 , N 2 , He, or N 2 O). It was found that all gases were trapped at very ventilation rates. As the rates were increased, however, the amount of gas trapped in the lungs decreased at ventilation rates which were characteristic of each particular gas. Gas trapping decreased first in lungs ventilated with SF 6 ,then N 2 , He, and finally N 2 O. The amount of gas trapped in the lungs at a given inflation-deflation rate was related to the solubility of the gas divided by the square root of its molecular weight. During the second part of the study the effect of different mixtures of SF 6 and O 2 on the amount of gas trapped was examined. All the results indicated that diffusion of gases through liquid walls of menisci or bubbles that occlude the airways is responsible for trapped gas in excised lungs.

A highly stable, easily built and operated circuit was designed to linearise the output of a particular photocell operating at the isobestic point of blood. In addition, the system was testedin vitro by simultaneously recording the total optical-density (o.d.) changes, and pulsatile o.d. changes observed when blood was perfused through a rigid tube and tubing capable of volume changes. The results showed different pulsatile o.d. changes, both in waveform and temporal sequence, for the rigid and distensible tubes.