Lung tissue mechanics and extracellular matrix composition in a murine model of silicosis.

The dynamic mechanical properties of lung tissue and its contents of collagen and elastic fibers were studied in strips prepared from mice instilled intratracheally with saline (C) or silica [15 (S15) and 30 days (S30) after instillation]. Resistance, elastance, and hysteresivity were studied during oscillations at different frequencies on S15 and S30. Elastance increased from C to silica groups but was similar between S15 and S30. Resistance was augmented from C to S15 and S30 and was greater in S30 than in S15 at higher frequencies. Hysteresivity was higher in S30 than in C and S15. Silica groups presented a greater amount of collagen than did C. Elastic fiber content increased progressively along time. This increment was related to the higher amount of oxytalan fibers at 15 and 30 days, whereas elaunin and fully developed elastic fibers were augmented only at 30 days. Silicosis led not only to pulmonary fibrosis but also to fibroelastosis, thus assigning a major role to the elastic system in the silicotic lung.     

Chromatographic separation of extruded iron-sulfur cores from the apoproteins of Clostridium pasteurianum and spinach ferredoxins in aqueous Triton X-100/urea

Iron-sulfur core extrusions from spinach [( 2Fe-2S]) and Clostridium pasteurianum (2[4Fe-4S]) ferredoxins in aqueous Triton X-100/urea containing excess benzenethiol yield quantitatively [FenSn(SPh)4]2- with n = 2 and n = 4, respectively. The iron-sulfur cluster can be separated from the corresponding apoprotein by rapid passage of the extrusion mixture over a small anaerobic column of Whatman DE-52 anion-exchange cellulose. Essentially quantitative recovery of [FenSn (SPh)4]2- is achieved in the eluate. The apoprotein remaining on the column can be eluted with 0.5 M NaCl. Most of the residual Triton X-100 and benzenethiol can be removed by passage of the apoprotein eluate over a small column of Bio-Beads SM-2, a hydrophobic polystyrene adsorbent. Apoprotein recovery is comparable to that obtained by other chromatographic methods. At least with spinach ferredoxin, the apoprotein prepared in this fashion can be reconstituted. The procedures developed in this work are potentially most applicable to selective removal of [2Fe-2S] and [4Fe-4S] centers from a multicenter enzyme without irreversible denaturation.     

Putative candidate genes for blood pressure control in the SHR.BN-RNO8 congenic substrains

The SHR-Lx congenic strain carrying a differential segment of chromosome 8 of BN and PD origin was recently shown to exhibit a significant decrease in blood pressure as compared to the SHR strain. There were two positional candidate genes for blood pressure control mapped to the differential segment: the rat kidney epithelial potassium channel gene (Kcnj1) and brain dopamine receptor 2 gene (Drd2). Bot these genes were separated into SHR.BN-RNO8 congenic substrains. In this communication, we are presenting the assignment of two further putative candidate genes, which might be involved in blood pressure control to the BN/PD differential segment of the SHR-Lx congenic strain. These are: the gene coding for smooth muscle cell specific protein 22 (Sm22) defined by the D8Mcw1 marker and neuronal nicotinic acetylcholine receptor gene cluster, defined by the D8Bord1 marker. Moreover, the glutamate receptor gene Grik4 which also maps to the differential segment of the SHR-Lx should be taken into account. The genetic separation of all these putative candidate genes of blood pressure control is being performed by recombinations and subsequent selection using (SHR×SHR-Lx) intercross population.     

Personality,Relationship Conflict,and Teamwork-Related Mental Models

This study seeks to explore whether neuroticism, agreeableness, and conscientiousness moderate the influence of relationship conflict experienced in groups on changes in group members'' evaluative cognitions related to teamwork quality (teamwork-related mental models). Data from 216 students, nested in 48 groups were analyzed using a multilevel modeling approach. Our results show that the experience of relationship conflict leads to a negative shift from the pre-task to the post-task teamwork-related mental models. Moreover, the results indicate that conscientiousness buffered the negative association between relationship conflict and the change in teamwork-related mental models. Our results did not support the hypothesized moderating effect of agreeableness and show that the detrimental effect of relationship conflict on the shift in teamwork-related mental models is accentuated for group members scoring low rather than high on neuroticism. These findings open new research venues for exploring the association between personality, coping styles and change in teamwork-related mental models.     

Structural and Functional Impact of SRP54 Mutations Causing Severe Congenital Neutropenia

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Biomechanical rationale of coronary artery bypass grafting of multivessel disease

The biomechanical model of human coronary arteries was modified for improving the quality of diagnosis and surgical treatment for coronary heart disease. The problem of hemodynamics in the left coronary artery with multivessel bed disease – 45% stenosis of the anterior descending branch and 75% stenosis of the circumflex branch – was particularly considered. Numerical simulation of the coronary arterial bypass of the main trunk was carried out to estimate the functional condition of the coronary arteries after restoring myocardial blood supply by surgery.     

Temperature-shift analysis of conidial development in Aspergillus nidulans

Temperature-shift experiments have been performed on spore-originated colonies of 11 thermosensitive aconidial mutants of Aspergillus nidulans in order to determine the latest time of shift to the restrictive temperature that prevents the initiation of conidiation. This time defines the beginning of the thermosensitive period (TSP) of the mutant. Eight of the mutants have TSPs that begin in the 7-hour period (32–39 hr) just prior to the first appearance of conidia-bearing structures, while 3 of the mutants have TSPs that begin later and very close to the time of onset of conidiation (45 hr). Thus no mutant of the set has a TSP that begins during the first 32 hr of vegetative growth of spore-originated colonies. For all mutants, an upshift performed after the beginning of the TSP allows initiation of conidiation at close to the normal time and at the normal rate, but results in an abrupt cessation of conidiation at some fixed time after upshift, characteristic of the mutant. The mutant whose TSP begins the earliest (aco-49) is exceptional in that, if conidiation is suppressed by growth of colonies in submerged culture, this mutant becomes thermoinsensitive during vegetative submerged growth; in contrast, the remaining 10 mutants become thermoinsensitive only after the suppressive condition has been relieved. We discuss the possibility that this exceptional mutant is defective in a function required for initiation of the process that ultimately results in the formation of conidia.     

Recognition of the beta-2 microglobulin-B molecule by a CTL clone

In this report we offer evidence that the beta-2 microglobulin-B (beta 2M-B) molecule is recognized by a cytotoxic T lymphocyte (CTL). Production of GA5, a CTL clone reactive against a membrane antigen with the same strain distribution pattern as beta 2M-B, is described. This clone lysed syngeneic target cells in which native beta 2M-A molecules had been exchanged with beta 2M-B molecules by incubating the cells in serum from beta 2M-B-positive mouse strains. Conversely, the CTL clone GA5 failed to lyse its specific target when beta 2M-B molecules had been exchanged with beta 2M-A molecules by incubating the cells in serum from beta 2M-A-positive, beta 2M-B-negative mouse strains. Strain combinations were chosen so as to limit reactivity to beta 2M and to preclude reactivity to H-3 antigens, thus indicating CTL clone GA5 to be reacting specifically with beta 2M-B.     

Comparisons of redox kinetics of methemerythrin and mu-sulfidomethemerythrin. Implications for interactions with cytochrome b5

We have examined the effects on redox kinetics of changing the reduction potential of the mu-oxo-bridged binuclear iron center in octameric hemerythrin (Hr) from Phascolopsis gouldii. The opportunity to examine such effects is provided by the availability of mu-sulfidomethemerythrin (mu-S2-metHr), whose [Fe(III),Fe(III)]met----[Fe(II),Fe(III)]semi-met reduction potential is approximately 200 mV higher than that of methemerythrin (metHr). We have used, as redox partners to Hr, a set of metal complexes and the heme proteins deoxymyoglobin (Mb) and cytochrome b5. The latter protein from P. gouldii is a presumed physiological redox partner of Hr. Similar kinetics at pH 8 in the presence or absence of the allosteric effector perchlorate suggest reduction of the iron atom closer to the outer surface of each subunit in the Hr octamer during the met----semi-met transformation. For all reducing agents, the experimentally determined ratio of second-order rate constants for reductions of mu-S2-metHr and metHr, k12(mu-S2-met)/k12(met), is close to the value of 40 predicted by the simple Marcus relation for "outer-sphere" electron transfer. For oxidations of (semi-met)RHr and mu-S2-semi-metHr, the predicted value of 40 for k12[(semi-met)R]/k12(mu-S2-semi-met) is closely approximated when Fe(CN)6(3-) is used as oxidant. The ionic strength dependence of the second-order rate constant suggests electrostatic interactions of opposite charges during reduction of metHr by P. gouldii cytochrome b5.(ABSTRACT TRUNCATED AT 250 WORDS)