Functions and regulation of NF-kappaB RelA during pneumococcal pneumonia

Eradication of bacteria in the lower respiratory tract depends on the coordinated expression of proinflammatory cytokines and consequent neutrophilic inflammation. To determine the roles of the NF-kappaB subunit RelA in facilitating these events, we infected RelA-deficient mice (generated on a TNFR1-deficient background) with Streptococcus pneumoniae. RelA deficiency decreased cytokine expression, alveolar neutrophil emigration, and lung bacterial killing. S. pneumoniae killing was also diminished in the lungs of mice expressing a dominant-negative form of IkappaBalpha in airway epithelial cells, implicating this cell type as an important locus of NF-kappaB activation during pneumonia. To study mechanisms of epithelial RelA activation, we stimulated a murine alveolar epithelial cell line (MLE-15) with bronchoalveolar lavage fluid (BALF) harvested from mice infected with S. pneumoniae. Pneumonic BALF, but not S. pneumoniae, induced degradation of IkappaBalpha and IkappaBbeta and rapid nuclear accumulation of RelA. Moreover, BALF-induced RelA activity was completely abolished following combined but not individual neutralization of TNF and IL-1 signaling, suggesting either cytokine is sufficient and necessary for alveolar epithelial RelA activation during pneumonia. Our results demonstrate that RelA is essential for the host defense response to pneumococcus in the lungs and that RelA in airway epithelial cells is primarily activated by TNF and IL-1.     

Effects of changes in central blood volume on carotid-vasomotor baroreflex sensitivity at rest and during exercise.

The purpose of this investigation was to examine whether the effect of changes in central blood volume on carotid-vasomotor baroreflex sensitivity at rest was the same during exercise. Eight men (means +/- SE: age 26 +/- 1 yr; height 180 +/- 3 cm; weight 86 +/- 6 kg) participated in the present study. Sixteen Torr of lower body negative pressure (LBNP) were applied to decrease central venous pressure (CVP) at rest and during steady-state leg cycling at 50% peak O2 uptake (104 +/- 20 W). Subsequently, infusions of 25% human serum albumin solution were administered to increase CVP at rest and during exercise. During all protocols, heart rate, arterial blood pressure, and CVP were recorded continuously. At each stage of LBNP or albumin infusion, the maximal gain (G(max)) of the carotid-vasomotor baroreflex function curve was measured using the neck pressure and neck suction technique. LBNP reduced CVP and increased the G(max) of the carotid-vasomotor baroreflex function curve at rest (+63 +/- 25%, P = 0.006) and during exercise (+69 +/- 19%, P = 0.002). In contrast to the LBNP, increases in CVP resulted in the G(max) of the carotid-vasomotor baroreflex function curve being decreased at rest -8 +/- 4% and during exercise -18 +/- 5% (P > 0.05). These findings indicate that the relationship between CVP and carotid-vasomotor baroreflex sensitivity was nonlinear at rest and during exercise and suggests a saturation load of the cardiopulmonary baroreceptors at which carotid-vasomotor baroreflex sensitivity remains unchanged.     

Evolutionary relationships among the male and female mitochondrial DNA lineages in the Mytilus edulis species complex

A novel form of mitochondrial DNA (mtDNA) inheritance has previously been documented for the blue mussel (Mytilus edulis). Female mussels inherit their mtDNA solely from their mother while males inherit mtDNA from both their mother and their father. In males, the paternal mtDNA is preferentially amplified so that the male gonad is highly enriched for the paternal mtDNA that is then transmitted from fathers to sons. We demonstrate that this mode of mtDNA inheritance also operates in the closely related species M. galloprovincialis and M. trossulus. The evolutionary relationship between the male and female mtDNA lineages is estimated by phylogenetic analysis of 455 nucleotides from the large subunit ribosomal RNA gene. We have found that the male and female lineages are highly divergent; the divergence of these lineages began prior to the speciation of the three species of blue mussels. Further, the separation between the male and female lineages is estimated to have occurred between 5.3 and 5.7 MYA.      

A role for anionic sites in epithelial architecture. Effects of cationic polymers on cell membrane structure

The effects of several cationic polymers (poly-L-lysines, protamine, and histone) on rabbit gall bladder epithelial cells were studied to explore possible roles for negative sites in the membrane. The tissue was bathed for 30 min at 37°C in Ringer''s solutions containing from 0.1 to 100.0 µg/ml of cationic polymers, and subsequently was fixed with 1% OsO₄ and examined with the electron microscope. All cationic polymers, at appropriate concentrations, produced similar changes in membrane structure. Adjacent membranes frequently were fused. Membrane structures such as microvilli lost rigidity. Cell membranes showed an apparent increase in permeability as judged by osmotically traumatized cells. These results indicate that fixed anionic sites play significant roles in stabilizing epithelial membrane structures.     

Construction of picoliter-nanoliter self-filling volumetric pipettes.

A technique is described whereby-volume, self-filling micropipettes can be constructed with minimal time and effort. The delivery volumes of such pipettes may range from several picoliters to more than 100 nl. The delivery of a given pipette of even the smallest volume is precise, generally yielding standard deviations much less than 1% of the mean volume as measured by liquid-scintillation counting of isotope dilutions. The technique offers considerable advantage to previously described techniques for constructing small constant-volume pipettes.     

Morphological and genetic variation in the endangered Sulawesi tortoise Indotestudo forstenii: evidence of distinct lineages?

Limited fieldwork and anecdotal evidence indicate that allopatric populations of the endangered Sulawesi tortoise (Indotestudo forstenii) differ in size and presence/absence of a nuchal scute, suggesting that these may constitute separate evolutionary lineages. We examined morphological and genetic variation to determine if the nuchal scute is correlated with size or genetic divergence. Our results indicate a strong correlation between size and nuchal scute such that turtles lacking a nuchal scute were larger than those possessing a nuchal scute. However, we found no correlation between genetic divergence and presence/absence of nuchal scutes, and thus no evidence of genetically differentiated lineages.