Effect of change in particle number on pulmonary clearance of aerosolized 99mTc-DTPA

Pulmonary clearance (PCl) of inhaled aerosolized 99mTc-diethylenetriamine pentaacetic acid (DTPA) across the alveolocapillary membrane is diffusion limited. Therefore, if the mixing of the 99mTc-DTPA in the aqueous hypophase underlying surfactant is slow or incomplete or if there were no hypophase, an increase in the alveolar surface area occupied by 99mTc-DTPA particles would increase the absorption rate. The aim of this study was to examine whether there is an effect on PCl of changing the number of inhaled particles. The change in particle number was accomplished by a setup of four parallel jet nebulizers feeding a central delivery chamber of 400 cm3. We performed two kinds of experiments in eight healthy nonsmokers between 28 and 52 yr of age. In the first experiment, 99mTc-DTPA in saline was nebulized in one nebulizer, while saline was nebulized in the other three. In the second experiment the number of inhaled particles containing 99mTc-DTPA was increased by a factor of four by nebulizing 99mTc-DTPA in saline in all four nebulizers simultaneously. Increasing the number of inhaled 99mTc-DTPA particles caused an increase in PCl of 24.2% (P less than 0.01). We conclude that there is a slight but significant effect of changing the number of DTPA particles on PCl and that this is probably due to an uneven mixing of the 99mTc-DTPA in the aqueous hypophase underlying the surfactant lining and the alveoli.     

Methyljasmonate and α-linolenic acid are potent inducers of tendril coiling

A coiling-inducing factor was isolated from tendrils of Bryonia dioica Jacq. and identified by infrared, ¹H-, ¹³C-nuclear magnetic resonance and mass spectrometry as -linolenic acid. When applied to detached tendrils, exogenous -linolenic acid, but not linoleic acid or oleic acid, induced tendril coiling. Further investigations showed that metabolites of -linolenic acid, jasmonic acid and, even more so, methyljasmonate, are highly effective inducers of tendril coiling in B. dioica. Methyljasmonate was most active when administered by air and, in atmospheric concentrations as low as 40–80 nM, induced a full free-coiling response with kinetics similar to mechanical stimulation. Even atmospheric levels as low as 4–5 nM methyljasmonate were still found to be significantly active. Methyljasmonate could be one of the endogenous chemical signals produced in mechanically stimulated parts of a tendril and, being highly volatile, act as a diffusible gaseous mediator spreading through the intracellular spaces to trigger free coiling of tendrils.Abbreviations EI-MS electron impact-mass spectrometry - HPLC high-performance liquid chromatography - IAA indole-3-acetic acid - NMR nuclear magnetic resonance - TFA trifluoroacetic acid We are indebted to the Deutsche Forschungsgemeinschaft, Bonn and the Fonds der Chemischen Industrie, Frankfurt (literature provision) for their support and to Dr. C. Brückner, Halle, for jasmonic-acid determinations.     

Bronchial hyperreactivity to leucotriene D4 and histamine in exogenous asthma.

Reactivity of the small and large airways to inhaled leucotriene D4, one of the leucotrienes that constitute slow reacting substance of anaphylaxis, was studied in eight patients with exogenous asthma and nine healthy subjects with no history of atopy. Non-cumulative dose response relations were constructed for leucotriene D4 in a randomised, double blind set up. Reactivity to the leucotriene was compared with reactivity to histamine in the two groups. Both groups reacted to leucotriene D4 with significant airway obstruction evident in forced expiratory volume in one second (FEV1), peak expiratory flow rate, maximal expiratory flow rate at 30% of forced vital capacity estimated from a partial flow volume curve initiated at 50% of vital capacity (V30), and an increase in volume of trapped gas. The airways of the patients were significantly (p less than 0.01) more reactive to leucotriene D4 than those of the controls. The differences were in order of magnitude, 10(2)-10(3) for FEV1 but only about 15 for V30 (p less than 0.05). The hyperreactivity of the airways of the asthmatic subjects to leucotriene D4 was comparable to that to histamine. Inhalation of leucotriene D4 caused pronounced dyspnoea only among the patients. The findings suggest a role for leucotriene D4 in human bronchial asthma.     

Transgenetic studies implicate interactions between homologous PrP isoforms in scrapie prion replication

Transgenic (Tg) mice expressing both Syrian hamster (Ha) and mouse (Mo) prion protein (PrP) genes were used to probe the mechanism of scrapie prion replication. Four Tg lines expressing HaPrP exhibited distinct incubation times ranging from 48 to 277 days, which correlated inversely with HaPrP mRNA and HaPrPC. Bioassays of Tg brain extracts showed that the prion inoculum dictates which prions are synthesized de novo. Tg mice inoculated with Ha prions had approximately 10(9) ID50 units of Ha prions per gram of brain and less than 10 units of Mo prions. Conversely, Tg mice inoculated with Mo prions synthesized Mo prions but not Ha prions. Similarly, Tg mice inoculated with Ha prions exhibited neuropathologic changes characteristic of hamsters with scrapie, while Mo prions produced changes similar to those in non-Tg mice. Our results argue that species specificity of scrapie prions resides in the PrP sequence and prion synthesis is initiated by a species-specific interaction between PrPSc in the inoculum and homologous PrPC.     

Reinstatement of Chiastocaulon Carl (Plagiochilaceae), Based on Evidence from Nuclear Ribosomal ITS and Chloroplast Gene rps4 Sequences

Abstract: Morphological approaches have led to controversial opinions regarding the systematic position of the Asian Jungermannia dendroides Nees within the family Plagiochilaceae. In recent times, the taxon was treated both as genus Chiastocaulon Carl, as a member of Plagiochila sect. Dendroideae Gottsche, Lindenb. and Nees, and as a representative of Plagiochila subgen. Chiastocaulon (Carl) Inoue. Sequences of the chloroplast‐encoded rps4 gene and the internal transcribed spacers of nuclear ribosomal DNA of 28 representatives of the Plagiochilaceae and Herbertus subdentatus (Herbertaceae, outgroup) were obtained to test the different hypotheses. Maximum likelihood analyses were performed, both on the separate and combined data sets, and in all cases resulted in a single optimal topology. The different phylogenies were congruent, but the analyses of the combined data set led to an overall more significant bootstrap support. Jungermannia dendroides was placed in a moderately supported clade with Pedinophyllum interruptum and Plagiochilion mayebarae, sister to the well supported Plagiochila clade. The topology justifies the recognition of Jungermannia dendroides as genus Chiastocaulon. Plagiochila frondescens (Nees) Lindenb., P. fruticosa Mitt. and P. pulcherrima Horik., placed alongside Chiastocaulon/Plagiochila dendroides by some authors, form a robust clade within Plagiochila (Dumort.) Dumort., assignable to P. sect. Fruticosae Inoue. The three species share the dendroid habit and alternating foliation with Chiastocaulon dendroides but lack well developed ventral intercalary branches. 11 sectional clades with robust bootstrap support were identified within the Plagiochila lineage. Many morphological characters of monophyletic lineages within the Plagiochilaceae appeared homoplastic, indicating that a natural subdivision of the family is only possible by the integration of molecular data. The molecular topologies justify a hierarchical subdivision of Plagiochila at some point in the future; however, well supported sectional groups of the molecular trees will presumably lack morphological autapomorphisms.     

Propagation of prion strains through specific conformers of the prion protein.

Two prion strains with identical incubation periods in mice exhibited distinct incubation periods and different neuropathological profiles upon serial transmission to transgenic mice expressing chimeric Syrian hamster/mouse (MH2M) prion protein (PrP) genes [Tg(MH2M) mice] and subsequent transmission to Syrian hamsters. After transmission to Syrian hamsters, the Me7 strain was indistinguishable from the previously established Syrian hamster strain Sc237, despite having been derived from an independent ancestral source. This apparent convergence suggests that prion diversity may be limited. The Me7 mouse strain could also be transmitted directly to Syrian hamsters, but when derived in this way, its properties were distinct from those of Me7 passaged through Tg(MH2M) mice. The Me7 strain did not appear permanently altered in either case, since the original incubation period could be restored by effectively reversing the series of passages. Prion diversity enciphered in the conformation of the scrapie isoform of PrP (PrP(Sc)) (G. C. Telling et al., Science 274:2079-2082, 1996) seems to be limited by the sequence of the PrP substrates serially converted into PrP(Sc), while prions are propagated through interactions between the cellular and scrapie isoforms of PrP.     

Innervation of the synovial membrane of the cats joint capsule

Summary Results of investigations on the occurrence of nerve fibres and endings in the synovial membrane of the knee and elbow joint in the cat are reported. The stratum synoviale contains only autonomic fibres, running in the adventitia of arteries.Free nerve endings are lacking in the stratum synoviale. Simple Pacinian corpuscles with an inner core are occasionally observed in the border zone between the stratum synoviale and fibrosum. The ultrastructure of these endorgans resembles that of Pacinian corpuscles in the hairless and hairy skin of the cat.