Tidal volume single breath washout of two tracer gases--a practical and promising lung function test

Background

Small airway disease frequently occurs in chronic lung diseases and may cause ventilation inhomogeneity (VI), which can be assessed by washout tests of inert tracer gas. Using two tracer gases with unequal molar mass (MM) and diffusivity increases specificity for VI in different lung zones. Currently washout tests are underutilised due to the time and effort required for measurements. The aim of this study was to develop and validate a simple technique for a new tidal single breath washout test (SBW) of sulfur hexafluoride (SF₆) and helium (He) using an ultrasonic flowmeter (USFM).

Methods

The tracer gas mixture contained 5% SF₆ and 26.3% He, had similar total MM as air, and was applied for a single tidal breath in 13 healthy adults. The USFM measured MM, which was then plotted against expired volume. USFM and mass spectrometer signals were compared in six subjects performing three SBW. Repeatability and reproducibility of SBW, i.e., area under the MM curve (AUC), were determined in seven subjects performing three SBW 24 hours apart.

Results

USFM reliably measured MM during all SBW tests (n = 60). MM from USFM reflected SF₆ and He washout patterns measured by mass spectrometer. USFM signals were highly associated with mass spectrometer signals, e.g., for MM, linear regression r-squared was 0.98. Intra-subject coefficient of variation of AUC was 6.8%, and coefficient of repeatability was 11.8%.

Conclusion

The USFM accurately measured relative changes in SF₆ and He washout. SBW tests were repeatable and reproducible in healthy adults. We have developed a fast, reliable, and straightforward USFM based SBW method, which provides valid information on SF₆ and He washout patterns during tidal breathing.     

Human adipose stem cells: current clinical applications

Adipose-derived stem cells are multipotent cells that can easily be extracted from adipose tissue, are capable of expansion in vitro, and have the capacity to differentiate into multiple cell lineages, which have the potential for use in regenerative medicine. However, several issues need to be studied to determine safe human use. For example, there are questions related to isolation and purification of adipose-derived stem cells, their effect on tumor growth, and the enforcement of U.S. Food and Drug Administration regulations. Numerous studies have been published, with the interest in the potential for regenerative medicine continually growing. Several clinical trials using human adipose stem cell therapy are currently being performed around the world, and there has been a rapid evolution and expansion of their number. The purpose of this article was to review the current published basic science evidence and ongoing clinical trials involving the use of adipose-derived stem cells in plastic surgery and in regenerative medicine in general. The results of the studies and clinical trials using adipose-derived stem cells reported in this review seem to be promising not only in plastic surgery but also in a wide variety of other specialties. Nevertheless, those reported showed disparity in the way adipose-derived stem cells were used. Further basic science experimental studies with standardized protocols and larger randomized trials need to be performed to ensure safety and efficacy of adipose-derived stem cells use in accordance with U.S. Food and Drug Administration guidelines.     

Potent and selective inhibitors of PI3Kδ: obtaining isoform selectivity from the affinity pocket and tryptophan shelf

A potent inhibitor of PI3Kδ that is ≥ 200 fold selective for the remaining three Class I PI3K isoforms and additional kinases is described. The hypothesis for selectivity is illustrated through structure activity relationships and crystal structures of compounds bound to a K802T mutant of PI3Kγ. Pharmacokinetic data in rats and mice support the use of 3 as a useful tool compound to use for in vivo studies.     

Molecular identification of temperate Cricetidae and Muridae rodent species using fecal samples collected in a natural habitat

Molecular species identification from biological material collected at field sites has become an established ecological tool. However, extracting and amplifying DNA from degraded field samples, such as prey remains and feces that have been exposed to the elements, remains a challenge and costly. We collected 115 fecal samples of unknown small mammals, resembling fecal droppings of voles and mice (i.e., Cricetidae and Muridae), from a salt marsh in The Netherlands. We modified a previously published protocol into a relatively low-cost method with a PCR success of 95%. We demonstrate that species identification is possible for both Cricetidae and Muridae species using fecal samples of unknown age deposited in the field. For 90 samples, sequences of the variable control region in the mitochondrial genome were obtained and compared to published DNA sequences of small mammals occurring in north European salt marshes. A single sample, probably environmentally contaminated, appeared as Sus scrofa (n?=?1). We positively identified house mouse Mus musculus, being the positive control (n?=?1), and common vole Microtus arvalis (n?=?88). In 81 sequences of 251 nt without ambiguous bases, ten haplotypes were present. These haplotypes, representing the central lineage of the western subspecies M. arvalis arvalis, were separated by 20 mutations from published control region haplotypes of the western European lineages sampled in France. Unlike earlier studies of cytochrome b variation in coastal European populations, we did not find indications of recent purging of genetic variation in our study area.     

Electrochemical study of mononucleosome

The electrochemical behavior of mononucleosome has been studied in parallel with circular dichroism and trypsin degradation. In mononucleosome, DNA is never adsorbed at the electrode surface. A model of flat adsorption of the mononucleosome via histones is proposed.     

C-glycosylflavones from Oryza sativa

Eight flavone C-glycosides isolated from rice plant were found to act as probing stimulants for planthoppers. They have been identified as the known compounds schaftoside, neoschaftoside, carlinoside, isoorientin 2″-glucoside and the new constituents neocarlinoside (6-C-β-D-glucopyranosyl-8-C-β-L-arabinopyranosylluteolin), isoscoparin 2″-glucoside (chrysoeriol 6-C-β-D-(2-O-β-D-glucopyranosyl)glucopyranoside) and its 6?-p-coumaric and ferulic acid esters.     

6-c-β-d-glucopyranosyl-8-c-β-d-galactopyranosylapigenin from cerastium arvense

The new C-glycosyiflavone, 6-C-β-d-glucopyranosyl-8-C-β-d-galactopyranosylapigenin, has been isolated from Cerastium arvense and identified on the basis of UV, MS and ¹³C NMR spectral data and comparison with the product obtained from 6-C-galactosylation of vitexin.     

The flavonoids of Trichophorum cespitosum

Fifteen flavonoids were isolated from Trichophorum cespitosum, including two new di-C-glycosylflavones, 6-C -arabinosyl-8-C-glucosylchr     

The compositional patterns of the avian genomes and their evolutionary implications

The compositional distributions of large (main-band) DNA fragments from eight birds belonging to eight different orders (including both paleognathous and neognathous species) are very broad and extremely close to each other. These findings, which are paralleled by the compositional similarity of homologous coding sequences and their codon positions, support the idea that birds are a monophyletic group.The compositional distribution of third-codon positions of genes from chicken, the only avian species for which a relatively large number of coding sequences is known, is very broad and bimodal, the minor GC-richer peak reaching 100% GC. The very high compositional heterogeneity of avian genomes is accompanied (as in the case of mammalian genomes) by a very high speciation rate compared to cold-blooded vertebrates which are characterized by genomes that are much less heterogeneous. The higher GC levels attained by avian compared to mammalian genomes might be correlated with the higher body temperature (41–43°C) of birds compared to mammals (37°C).A comparison of GC levels of coding sequences and codon positions from man and chicken revealed very close average GC levels and standard deviations. Homologous coding sequences and codon positions from man and chicken showed a surprisingly high degree of compositional similarity which was, however, higher for GC-poor than for GC-rich sequences. This indicates that GC-poor isochores of warm-blooded vertebrates reflect the composition of the isochores of the genome of the common reptilian ancestor of mammals and birds, which underwent only a small compositional change at the transition from cold- to warm-blooded vertebrates. In contrast, the GC-rich isochores of birds and mammals are the result of large compositional changes at the same evolutionary transition, where were in part different in the two classes of warm-blooded vertebrates.Correspondence to: G. Bernaadi