Characteristics of strains of Citrobacter 037 (5396/38) isolated from guinea pigs in a gnotobiologic experiment

No changes in the principal biochemical properties characteristic of the given genus occurred in a gnotobiological experiment of passing Citrobacter bacteria through microbe free and exmicrobe-free animals. Of 28 strains of this genus isolated in the course of investigation two strains lost their arginine-decarboxylase activity. In the cultures studied the quantitative content of the Vi-antigen had a tendency to reduction in comparison with the initial culture used for the association. some of the strains studied had one more common antigen with typhoid bacilli (strain Ty2-4446) along with theknown cross by the Vi-antigen. Bacteria of the Enterobacter and Excherichia genus isolated after the conventionalization had common antigens with typhoid bacilli (Ty2-4446).     

Effect of climatic-weather conditions on the incidence of miscarriage

Two new methods for serological grouping of beta-hemolytic streptococci, the nitrous acid extraction procedure of El Kholy et al. and the slide agglutination method of Christensen et al., were compared with the Lancefield hot-hydrochloric acid extraction method in classifying 92 strains of groups A, B, C, and G. The nitrous acid extraction method was easily performed, specific, and sensitive when highly potent antisera were used. For the Christensen method these highly potent antisera had to be diluted to avoid cross-reactions between groups A and C and groups B and G, respectively. A few strains, most of them group B, could not be grouped by the latter method. Using these three grouping methods, two sets of commercial sera were compared with the more potent sera supplied by R. C. Lancefield. The low antibody content of these commercial sera, especially anti-group B and G sera, contributed to the inferior results obtained in some of the grouping reactions.     

Degradation of cardiac troponin I: implication for reliable immunodetection

We have analyzed by different immunological methods the proteolytic degradation of cardiac troponin I (cTnI) in human necrotic tissue and in serum. cTnI is susceptible to proteolysis, and its degradation leads to the appearance of a wide diversity of proteolytic peptides with different stabilities. N- and C-terminal regions were rapidly cleaved by proteases, whereas the fragment located between residues 30 and 110 demonstrated substantially higher stability, possibly because of its protection by TnC. We conclude that antibodies selected for cTnI sandwich immunoassays should preferentially recognize epitopes located in the region resistant to proteolysis. Such an approach can be helpful for a much needed standardization of cTnI immunoassays and can improve the sensitivity and reproducibility of cTnI assays.     

The genetic characteristics of the analgesic action of substance P, bradykinin and thyroliberin in the rats of 2 inbred strains

A participation of nonopiate peptide brain systems in the mechanism of individual pain sensation was studied. The experiments were carried out on rats of two inbred strains, Fischer-344 and WAG/G, which exhibit different threshold of thermal pain sensation. The action of nonopiate oligopeptides (substance P, bradykinin, and thiroliberin) on the latent period of tail immersion from hot water was studied. It was found that significant analgesic action of substance P, bradykinin, and thiroliberin is more pronounced in rats more sensitive to thermal stimuli (WAG/G). The rats with reduced thermal sensitivity (Fischer-344) are shown to be insensitive to analgesic action of substance P, bradykinin, and thiroliberin.     

Spontaneous liposome formation induced by grafted poly(ethylene oxide) layers: theoretical prediction and experimental verification

Spontaneous liposome formation is predicted in binary mixtures of fluid phase phospholipids and poly(n)ethylene oxide (PEO)-bearing lipids by using single chain mean field theory. The range of stability of the spontaneous liposomes is determined as a function of percentage of PEO-conjugated lipids and polymer molecular weight. These predictions were tested by using cast films of 1, 2-diacyl-sn-glycerophosphocholines (e.g., egg L-alpha-lecithin, 1, 2-dimyristoyl-sn-glycero-3-phosphocholine, 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine, and 1, 2-distearoyl-sn-glycero-3-phosphocholine) and 1, 2-dipalmitoyl-sn-glycerophosphatidylethanolamine-PEO conjugates (i.e. , 1, 2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[methoxypoly(e thylen e glycol)2000]carboxamide and 1, 2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[methoxypoly(e thylen e oxide)5000]carboxamide) that were hydrated above their gel-liquid crystal phase transition temperatures. Particle sizes of the resulting dispersions, analyzed by quasielastic light scattering, solute retention, 31P NMR, and freeze-fracture electron microscopy measurements, confirmed the single chain mean field predictions. These data indicate that thermodynamically stable, unilamellar liposomes are formed spontaneously by simple hydration of fluid phase phospholipid bilayer films containing low molar ratios of PEO-based amphiphiles. They further suggest that the equilibrium size and colloidal properties of fluid phase, PEO-modified liposomes can be predicted by using this theoretical approach. The implication of these results on the design and processing of sterically stabilized liposomes used in drug delivery applications also is described.     

New site-specific endonucleases from strains of Bacillus

In a search for new restriction endonucleases type II, among forty bacterial strains of the Bacillus genus two strains producing site-specific endonucleases have been found. Endonucleases BbvAIII and BspFI, isolated from B. brevis BLM B-677 and B. species F, are shown to be true isoschisomers of BspMII (Kpn2I) and Sau3AI, respectively.