Identification of bacterial chemoattractants for oyster (Crassostrea virginica) hemocytes

The cytoplasmic and cell wall components of the Gram-positive bacterium Bacillus megaterium and the cytoplasmic and cell envelope components of the Gram-negative bacterium Escherichia coli were assayed for chemotactic activity for the hemocytes of Crassostrea virginica. The cellular components were separated by differential centrifugation and gel filtration was used to determine the approximate molecular weights of the chemoattractant molecules. Active fractions were assayed for glycoproteins and lipoproteins. As a result, it is known that hemocytes are chemotactically attracted to proteins of approximately 10,000 daltons which are associated with the cell wall of B. megaterium and the cell envelope of E. coli.     

Relation between diameter and flow in branches of the bronchial tree

Two methods are described for calculating the value of the exponentx in the equation flow =k×diameter ^x , as pertaining to a branch of the bronchial tree. In the lungs from three humans, two dogs, one hamster, and one rat mean values ofx between 2.419 and 2.903 were found. They lie within the range of 2.333 to 3.0 predicted by the analysis of Uylings (Bull. Math. Biol. 39, 501–519, 1977).     

Controlled trial of supervised exercise training in chronic bronchitis.

In a controlled trial of exercise retraining in patients with severe chronic bronchitis, 33 subjects were followed for a mean period of 10.3 months. The exercise programme was supervised once a week, and daily training comprised a 12-minute walk and simple stair climbing exercises. The subjects in the exercise group showed a highly significant improvement in their walking distance, attaining a maximum increase of 24% after eight to 12 months. There was also considerable subjective improvement. The control group did not improve. No significant changes in cardiorespiratory function or muscle strength were seen. Simple exercise rehabilitation is of benefit to patients with disabling obstructive lung disease.     

Compartmental analysis of sulphate transport in Lemna minor L., taking plant growth and sulphate metabolization into consideration

Rat hepatoma cells accumulate considerably less 2-aminoisobutyrate after cultivating in the absence of serum the change in rate of aminoisobutyrate uptake takes place within 1 h of serum starvation. Starvation of amino acids by contrast raises aminoisobutyrate uptake in the presence or absence of serum, but the cells are much less responsive to amino acid supply than to availability of serum. Phosphate (10 mM) reduced aminoisobutyrate uptake by cells grown in serum to that exhibited by serum-starved cells. Aminoisobutyrate uptake by cells grown in serum was reduced by glycine, proline, alanine, serine, glutamine, methylaminoisobutyrate and 2-aminonorbornane-2-carboxylate, the effects of methylaminoisobutyrate and 2-aminonorbornane-2-carboxylate being additive. However, similar inhibition phenomena were not seen for cells deprived of serum where aminoisobutyrate uptake tended to a relatively constant level insensitive to inhibitory influences, yet substantially greater than that arising by simple diffusion. The comparative insensitivity of our hepatoma line when starved of serum to competition and repression phenomena is in contrast to findings of others. Our results also suggest a lack of clear delineation of specificities for the A and L transport systems as usually defined.     

Antigen-induced histamine release from sensitized tissue and the measurement of calcium ion fluxes

Antigen stimulated release of histamine from sensitized guineapig lung was inhibited by the exclusion of calcium ions from the incubation fluid. Subsequent addition of calcium ions induced release, but the magnitude of this release decreased with time. When the releasing potential had declined to zero, addition of an alternative antigen together with calcium ions induced further release. If the primary challenge was inhibited by the presence of an antiallergic agent, challenge by a second antigen was similarly inhibited, in contrast to the effect when there was no primary antigen challenge. Antigen challenge induced a flux of ${}^{45}\text{Ca}$ into cells, these fluxes were inhibited by compounds which inhibited histamine release. Inhibition of release did not correlate with inhibition of calcium flux with some agents, suggesting that the measured flux is the sum of at least two fluxes, one secondary to release. These results are explained in a scheme for antigen-induced histamine release.     

Cell patterning in branched and unbranched fruiting bodies of the cellular slime mold Polysphondylium pallidum

Cell patterning, the percentage of spores and stalk cells, was measured in branched and unbranched asexual fruiting bodies of Polysphondylium pallidum. Unlike D. discoideum, where small and large fruiting bodies are more stalky than average-sized fruiting bodies, the overall cell patterning was the same in branched and unbranched fruiting bodies of all sizes in P. pallidum. Light greatly increased the numbers of fruiting bodies in P. pallidum per unit area (or decreased aggregation territory size) so that most fruiting bodies formed in the light were small and unbranched. By contrast, light had little effect on the cell patterning of P. pallidum, although there was a slight increase in the percentage of stalk cells in the light compared to the dark. This indicates that the mechanisms governing light sensitivity of aggregation territory size and cell patterning have different components in P. pallidum. The accuracy of cell patterning of individual branches of branched fruiting bodies was so imprecise as to leave doubt that patterning is occurring at the branch level. Individual whorls of branched fruiting bodies had a greater percentage spores (90%) than whole fruiting bodies (78%) and the cell patterning was relatively imprecise. Only in whole fruiting bodies was the spore:stalk ratio highly correlated. These findings are consistent with cell pattern determination operating at the whole aggregate level, rather than at the individual whorl or branch level in P. pallidum.     

The primary structure of rabbit, calf and bovine liver tRNAPhe.

Highly purified tRNAPhe from rabbit liver, calf liver and bovine liver were completely digested with pancreatic ribonuclease and ribonuclease T1. The oligonucleotides were separated and identified. The tRNAPhe from rabbit liver and calf liver were partially cleaved with ribonuclease T1 or by action of lead acetate. We describe the analyses of the large fragments and the derivation of the primary structure of these mammalian tRNAsPhe.     

Interaction of alcohols with proteins

The kinetics of denaturation of egg albumin have been determined for methanol, ethanol, propanol, and butanol. The reactions are first order in respect to protein but between 11th and 18th order for the alcohols. The denaturation reaction is characterized by a large temperature coefficient with little or no dependence on pH. There is a marked change of pH when proteins are denatured. A series of eight proteins has been studied. There is surprisingly little difference in susceptibility to alcohol denaturation between the various proteins. Methanol, ethanol, propanol, and butanol are strongly bound to egg albumin—butanol being the most strongly bound. The binding of alcohol is probably accompanied by protein dehydration. The polyhydric alcohols' behavior is much different. These alcohols do not denature proteins and the protein is hydrated. Sucrose produces the greatest degree of hydration.