Antibiotic, Detergent, and Complement Sensitivity of Salmonella typhi After Ethylenediaminetetraacetic Acid Treatment

Antimicrobial substances, including antibiotics such as polymyxin and novobiocin, detergents, and complement, all of which are known or presumed to have an effect upon membrane permeability, showed greater potency against ethylenediaminetetraacetic acid (EDTA)-treated Salmonella typhi than against untreated cells of that organism. The differential effect was particularly marked with the complement system when serum antibody was limiting. EDTA-treated cells were also more susceptible to penicillin and bacitracin. On the other hand, such treatment did not affect the potency against S. typhi of mitomycin C, the aminoglycosides, chloramphenicol, and chlortetracycline, nor did it affect the permeability of S. typhi to these compounds.     

Tea tree oil causes K+ leakage and inhibits respiration in Escherichia coli

Concentrations of tea tree oil (TTO) which inhibit or decrease growth of Escherichia coli also inhibit glucose-dependent respiration and stimulate the leakage of intracellular K⁺. Stationary phase cells are more tolerant to these TTO effects than exponential phase cells.     

Effect of prostaglandin F2 alpha on pulmonary rapidly-adapting-receptors in the guinea pig

Pulmonary rapidly-adapting-receptors ( RARs ) are sensory nerve endings whose afferent fibers can be recorded in the vagus nerve. RARs may play a role in reflex bronchoconstriction as seen in anaphylaxis. They can be stimulated by chemical mediators of anaphylaxis, such as prostaglandin F2 alpha (PGF2 alpha). PGF2 alpha aerosol was administered to saline and bovine serum albumin (BSA)-treated guinea pigs while recording the activity of RARs . PGF2 alpha (250 micrograms/ml) given for 7-13 minutes increased both tracheal pressure and nerve activity over that produced by saline exposure in untreated guinea pigs. PGF2 alpha administered for three minutes (5-100 micrograms/ml) increased RAR nerve activity in a dose-related manner in the first five minutes of the experiment only in the BSA treated guinea pigs. Since changes in tracheal pressure did not show a significant dose-response relationship, the RARs responding to PGF2 alpha seemed to be stimulated by a direct mechanism. No correlation was shown between tracheal pressure and RAR nerve activity during PGF2 alpha treatment. Whereas, a significant correlation was found between tracheal pressure and RAR nerve activity during histamine aerosol treatment (r = 0.985). Histamine aerosol (1 to 1000 micrograms/ml, 3 min.) increased intratracheal pressure for 3 out of 4 doses. RAR nerve activity increased significantly only at the highest dose. Therefore, a possible direct effect of PGF2 alpha upon RARs exists while the effect of histamine seems dependent upon changes in airway pressure in the guinea pig.     

The New World whirligig beetles of the genus Dineutus Macleay, 1825 (Coleoptera,Gyrinidae, Gyrininae,Dineutini)

All New World members of the whirligig beetle genus Dineutus Macleay, 1825 are treated. The New World Dineutus are found to be composed of 18 species and 6 subspecies: one species, Dineutus mexicanus Ochs, 1925, stat. n. is elevated from subspecies to species rank, and the subspecies Dineutus carolinus mutchleri Ochs, 1925, syn. n. is synonymized here with the typical form. Lectotypes are designated for Dineutus discolor Aubé, 1838, Dineutes metallicus Aubé, 1838, Dineutus solitarius Aubé, 1838, Dineutes analis Régimbart, 1883, and Gyrinus longimanus Olivier, 1795. Each taxonomic unit is provided with a taxonomic history, type locality, diagnosis, distribution, habitat information, and a discussion section. The aedeagus and male mesotarsal claws are illustrated, and dorsal and ventral habitus images of both sexes, for each species and subspecies are provided. General distribution maps are provided for all taxonimc units. A key to the genera of New World Gyrinidae, as well as all the New World Dineutus species is provided. General Dineutus anatomy as well as a clarification of homology and anatomical terms is included.