Chromosome studies on mosses from Austria,Czechoslovakia and other parts of Central Europe

Summary Reports are made on chromosomes in forty-six species from sixteen families of mosses. The plants were collected from all Austrian provinces, except the Tyrol and Vorarlberg, from Bohemia, Moravia, Slovakia, Bavaria, and also from Hungary and Italy. In addition to number or numbers of chromosomes reported for each species, observations are made on chromosome morphology, staining characteristics and behavior in meiosis or mitosis. The lowest numbers yet found are reported forDicranum fuscescens, n=8, andTimmia bavarica, n=8+1 m. For the latter species the study was made from mitotic configurations, and offers evidence that m-chromosomes may be normal members of the gametophytic set. These investigations reveal for the first time m-chromosomes inDicranoweisia cirrata, Pottia lanceolata, Timmia bavarica, Orthotrichum pumilum, Homalothecium lutescens, Brachythecium velutinum, Rhyncostegium murale, Rhyncostegiella pumila, andHypnum cupressiforme. Although the generaBartramia andPlagiopus previously have been characterized by different numbers of chromosomes, n=8 and n=7 respectively, plants ofPlagiopus oederi from Carinthia and Moravia were found, however, to have n=8. One species,Isopterygium seligeri, and one variety,Orthotrichum anomalum var.saxatile, have not been studied previously.Grateful acknowledgement is made to (1) the United States National Science Foundation for partial support of this investigation by a grant of research funds (NSF GB 6725) to Duke University, and (2) the Botanisches Institut der Universität Wien for laboratory space, equipment and use of the herbarium and library.     

Diaphragmatic work of breathing in premature human infants

Present methods of assessing the work of breathing in human infants do not account for the added load when intercostal muscle activity is lost and rib cage distortion occurs. We have developed a technique for assessing diaphragmatic work in this circumstance utilizing measurements of transdiaphragmatic pressure and abdominal volume displacement. Eleven preterm infants without evidence of lung disease were studied. During periods of minimal rib cage distortion, inspiratory diaphragmatic work averaged 5.9 g X cm X ml-1, increasing to an average of 12.4 g X cm X ml-1 with periods of paradoxical rib cage motion (P less than 0.01). Inspiratory work was strongly correlated with the electrical activity of the diaphragm as measured from its moving time average (P less than 0.05). Assuming a mechanical efficiency of 4% in these infants, the caloric cost of diaphragmatic work may reach 10% of their basal metabolic rate in periods with rib cage distortion. When lung disease is superimposed, the increased metabolic demands of the diaphragm may predispose preterm infants to fatigue and may contribute to a failure to grow.     

Differential inhibition of the MLR by iron: Association with HLA phenotype

The effect of iron on the MLR was examined by pretreating peripheral blood mononuclear cells from 77 unrelated Caucasians with five concentrations of Ferric-citrate (10.0 mM, 1.0 mM, 0.1 mM, 0.01 mM and 0.005 mM). After incubation with the metal, the cells were washed and cultured in a one-way MLR with a pool of stimulator cells. Cell viability remained unchanged (greater than 90 percent) during the 6-day culture period. Citrate per se had no effect on either the responder or the stimulator population. Iron treatment influenced the MLR in the following ways: (1) a variable degree of inhibition was observed which related to the dose of Ferric-citrate used and to HLA phenotype, (2) the responder but not the stimulator cells were affected, (3) no statistically significant differences were seen between female and male donor cells and (4) the mean percent response of cells from HLA-A2 donors were significantly (0.005 The present results indicate that iron can interact with lymphoid cells and influence some immunological functions in vitro. The possibility is discussed that similar interactions take place in vivo which could contribute to the prognosis of certain diseases associated with particular HLA phenotypes.