In vivo hysteresis of airspace dimensions measured by aerosol recovery

In anesthetized mongrel dogs, we made measurements of single breath aerosol recovery (RC) at equal volume points on the inflation and deflation limb of the quasi-static pressure-volume (P-V) curve of the lungs. Using a 1.2 micron monodisperse aerosol, a large aerosol tidal volume (Vt), and a breathing period of 5 sec, we found that losses of particles were primarily due to sedimentation in pulmonary airspaces distal to anatomic dead space. Thus, the RC measurements could be related to a mean radius (R) of airspaces filled with aerosol over the course of the breath. Furthermore, at a given volume, differences between inflation and deflation limb RC could be attributed to differences in R for the two measurements (i.e., RI vs RD). We found that at isovolume, RC as measured from the inflation limb was larger than that measured from the deflation limb for low lung volumes (less than 0.75 TLC). However, the recoveries were similar as lung volume approached TLC (greater than 0.75 TLC). These results implied that at the same volume, RI greater than RD expect at volumes approaching TLC, i.e. a larger mean airspace dimension on the inflation limb than on the deflation limb at equal volume. The findings of this study support a model of nonuniform changes in airspace dimensions associated with in vivo inflation and deflation of the lungs.     

Extracorporeal cell therapy of septic shock patients with donor granulocytes: a pilot study

Introduction

Neutrophil granulocytes are the first defense line in bacterial infections. However, granulocytes are also responsible for severe local tissue impairment. In order to use donor granulocytes, but at the same time to avoid local side effects, we developed an extracorporeal immune support system. This first-in-man study investigated whether an extracorporeal plasma treatment with a granulocyte bioreactor is tolerable in patients with septic shock. A further intention was to find suitable efficacy end-points for subsequent controlled trials.

Methods

The trial was conducted as a prospective uncontrolled clinical phase I/II study with 28-day follow-up at three university hospital intensive care units. Ten consecutive patients (five men, five women, mean age 60.3 ± 13.9 standard deviation (SD) years) with septic shock with mean ICU entrance scores of Acute Physiology and Chronic Health Evaluation (APACHE) II of 29.9 ± 7.2 and of Simplified Acute Physiology Score (SAPS) II of 66.2 ± 19.5 were treated twice within 72 hours for a mean of 342 ± 64 minutes/treatment with an extracorporeal bioreactor containing 1.41 ± 0.43 × 10E10 granulocytes from healthy donors. On average, 9.8 ± 2.3 liters separated plasma were treated by the therapeutic donor cells. Patients were followed up for 28 days.

Results

Tolerance and technical safety during treatment, single organ functions pre/post treatment, and hospital survival were monitored. The extracorporeal treatments were well tolerated. During the treatments, the bacterial endotoxin concentration showed significant reduction. Furthermore, noradrenaline dosage could be significantly reduced while mean arterial pressure was stable. Also, C-reactive protein, procalcitonin, and human leukocyte antigen DR (HLA-DR) showed significant improvement. Four patients died in the hospital on days 6, 9, 18 and 40. Six patients could be discharged.

Conclusions

The extracorporeal treatment with donor granulocytes appeared to be well tolerated and showed promising efficacy results, encouraging further studies.

Trial registration

ClinicalTrials.gov Identifier: {"type":"clinical-trial","attrs":{"text":"NCT00818597","term_id":"NCT00818597"}}NCT00818597     

Variation in Airway Responsiveness of Male C57BL/6 Mice from 5 Vendors

Mice are now the most commonly used animal model for the study of asthma. The mouse asthma model has many characteristics of the human pathology, including allergic sensitization and airway hyperresponsiveness. Inbred strains are commonly used to avoid variations due to genetic background, but variations due to rearing environment are not as well recognized. After a change in mouse vendors and a switch from C57BL/6J mice to C57BL/6N mice, we noted significant differences in airway responsiveness between the substrains. To further investigate the effect of vendor, we tested C57BL/6N mice from 3 other vendors and found significant differences between several of the substrains. To test whether this difference was due to genetic drift or rearing environment, we purchased new groups of mice from all 5 vendors, bred them in separate vendor-specific groups under uniform environmental conditions, and tested male first generation (F1) offspring at 8 to 10 wk of age. These F1 mice showed no significant differences in airway responsiveness, indicating that the rearing environment rather than genetic differences was responsible for the initial variation in pulmonary phenotype. The environmental factors that caused the phenotypic variation are unknown. However, differences between vendor in feed components, bedding type, or microbiome could have contributed. Whatever the basis, investigators using mouse models of asthma should be cautious in comparing data from mice obtained from different vendors.Abbreviation: AHR, airway hyperresponsivenessIn studies of the mouse lung involving measurement of pulmonary function, investigators commonly use inbred strains of mice to ensure a common genetic background. When mice are genetically identical the effects of specific environmental or genetic perturbations can be studied independent of background genotype. However, the need to similarly control for the source of the inbred mice is not always so apparent. In an effort to reduce costs in ongoing studies involving lung function measurements, we switched vendors from The Jackson Laboratory to the National Cancer Institute. Initial studies with the C57BL/6NCr mice unexpectedly showed substantially less responsiveness of the airways compared with the C57BL/6J mice. This preliminary observation called into question the validity of comparisons between studies of C57BL/6 mice of different substrains purchased from different vendors. If the differences were due to genetic drift rather than environmental factors, the effect of this variation could extend to genetically engineered mouse models generated by using different C57BL/6 substrains.C57BL/6 substrains have a long history in the United States: they were so named because they originated as black offspring from female mouse number 57 and male mouse number 52 in a mating by Clarence Cook (CC) Little of Abbie Lathrop''s stock in 1921. CC Little subsequently founded the Jackson Laboratory, and the substrain C57BL/6 was established at The Jackson Laboratory prior to 1937.¹⁴ The sublines C57BL/6N and C57BL/6J were separated at NIH in 1951. Harlan and Charles River acquired their breeding colonies from NIH in 1974, Taconic in 1991, and the National Cancer Institute in 1996. These long passages of time would suggest that genetic mutations arising in different colonies could have resulted in genetically distinct substrains. However, several studies suggest only minimal differences exist.^29,32,44 Most recently, one study⁴⁴ evaluated 1449 single-nucleotide polymorphisms distributed over all 20 chromosomes in 10 C57BL/6 sources from Europe, Australia, and the United States. Of the 1449 single-nucleotide polymorphisms, only 12 were polymorphic between strains, and most could not be directly associated with a known gene. Although these single-nucleotide polymorphisms distinguished the B6/N substrains from the B6/J substrains, there were no differences within the 4 B6/N or the 3 primary B6/J sources, whereas a second group of 3 B6/J sources differed by 3 single-nucleotide polymorphisms from the primary B6/J sources.These minimal differences in genotype between B6 substrains suggested that environmental factors may have played the major role in the phenotypic differences we observed. Differences in phenotype attributable to environmental variation have previously been reported in several fields. For example, behavioral testing differences in inbred mice were attributed to different testing locations;¹¹ behavioral tests, tumor growth, and immunologic parameters were affected by veterinary treatments with fenbendazole,^15,17,25 and numerous research areas are affected by intercurrent infections.^9,14 In addition, differences in behavioral testing attributed to differences between B6/J and B6/N mice⁵ may have resulted from differences in rearing environment rather than genetic differences. However, to our knowledge, there have been no reports of differences in airway responsiveness in B6 mice from different vendors. To further describe this finding and to evaluate the differing roles of genetics and environment, we tested airway responsiveness in 5 substrains of male B6 mice from 5 different vendors in the United States and then repeated the tests in the male offspring of mice of the same substrains purchased from the same vendors but bred and maintained under uniform environmental conditions at our institution.     

Molecular adsorbent recycling system (MARS): clinical results of a new membrane-based blood purification system for bioartificial liver support

The use of xenogenic or genetically engineered cell types in bioartificial liver support systems requires separation methods between the patients' blood and the liver support bioreactors that guarantee the sufficient transfer of pathophysiologically relevant substances but prevent complications. The present paper describes a new membrane separation system that is nearly impermeable to proteins but enables the exchange of water soluble and protein bound toxins by a special membrane and a recycled protein containing dialysate. Because the full range of toxins in hepatic failure has still not been identified, the value of this membrane separation method was evaluated clinically. Thirteen patients suffering from life threatening hepatic failure who had not responded to state of the art therapy were treated with this device, the molecular adsorbent recycling system (MARS). The overall survival rate was 69%. All patients showed positive response to the therapy, indicating that the presented membrane separator combines therapeutic effectivity with the highest safety criteria for the patient by cutting the exchange of substances below the level of proteins.     

Potential cardiotonics. 7. Synthesis and cardiovascular effects of 5-(4-pyridinyl)-, 6-methyl-4-(4-pyridinyl) and 6-methyl-5-phenyl-substituted 3-cyano-2-aminoalkylamino-pyridines

The title compounds were synthesized by treating of 2-chloro-pyridines 1-3 with the appropriate aminoalkylamines or piperazines. In isolated guinea pig atria some compounds showed greater positive inotropic activity than amrinone. Heart rate was decreased or remained unchanged. In anesthetized dogs some derivatives exerted a dose-dependent increase in myocardial contractility and, additionally, a decrease in blood pressure.     

Different mechanisms of atelectasis formation require different treatment strategies

Several strategies have been developed to treat atelectasis, including positive end-expiratory pressure and deep inspirations. However, in some patients these recruitment strategies fail to improve lung function. Therefore, the authors studied whether recruitment maneuvers could resolve atelectasis following either passive airway closure or active bronchconstriction. Aerated lung areas were measured in 5 dogs at baseline, and after airway closure with either a bronchial blocker, or administration of methacholine, followed by deep inspiration. Finally, bronchoconstriction was reversed pharmacologically. Bronchial occlusion reduced aerated lung areas, which were reopened by deep inspirations. Following methacholine, aerated lung areas were also significantly reduced; however, deep inspirations had no significant effect. Passive atelectasis was easily resolved by deep inspirations. In contrast, active airway constriction that leads to atelectasis could not be overcome with recruitment maneuvers.     

Potential cardiotonic agents. 6. Synthesis and cardiovascular properties of 5-(4-pyridinyl)-, 6-methyl-5-(4-pyridinyl)- and 6-methyl-5-phenyl-substituted 3-cyano-2-oxaalkyoxy-pyridines

The headline compounds were prepared by the reaction of 2-chloropyridines 1-3 with the appropriate alcohols in presence of potassium hydroxide and the sodium alkoxides, respectively. Especially some of the 3-cyano-2-hydroxyalkoxy-5-(4-pyridinyl)pyridines showed remarkable positive inotropic potency and, additionally, a vasodilator activity. In spontaneously beating isolated guinea pig atria they had a greater activity than amrinone.