Novel piperidinyloxy oxazolidinone antimicrobial agents.

Oxazolidinone antibacterial agents, where the N-substituted piperazinyl group of eperezolid was replaced with a N-substituted piperidinyloxy moiety, were synthesized and shown to be active against a variety of resistant and susceptible Gram-positive organisms. The effect of ring size, positional isomerism, and fluorine substitution on antibacterial activity was examined.     

Initial verification of the resistance management strategy for Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) in Australia

Shortly after the initial detection of western flower thrips (WFT), Frankiniella occidentalis (Pergande), in Australia during 1993 a resistance management strategy based on the alternation of chemical groups was implemented. This study aimed to verify this strategy by field testing α-cypermethrin against WFT with and without chemical alternation. Up to 114 times α-cypermethrin resistance (at LC50) was detected and resistance increased with and without chemical alternation; however, chemical alternation did significantly reduce numbers of thrips compared with a nonalternation strategy. Resistance has the potential to undermine the sustainable use of those chemicals to which there is no current detectable resistance. Consequently, chemicals with a high frequency and level of resistance against WFT need to be identified through monitoring and quickly eliminated from WFT chemical control recommendations.     

Time of death of CNS tumor-bearing rats can be reliably predicted by body weight-loss patterns.

A request by the Institutional Animal Care and Use Committee for an alternative to death as an end point in a cancer research project using a rat brain 9L tumor cell model led to a search for reliable criteria for predicting time of death in this type of experiment. These experiments evaluated the therapeutic effectiveness of radiation alone, continuous intracerebral infusions of 5-iodo-2-deoxyuridine (IUDR) alone, and a combination of both therapies. We found that a characteristic pattern of body weight changes occurs after injection of 9L tumor cells into the brain ventricles or parenchyma. The initial phase was characterized by a loss of body weight which appeared to be related to surgery and, in the irradiated groups, to the subsequent doses of radiation under anesthesia on days 4, 6, and 7. After this initial phase (phase 1), a second period of weight change (phase 2) which was characterized by an overall gain of body weight interrupted temporarily in 76 out of the 149 rats by reversible episodes of weight loss of 1 to 5 days duration. The length of this phase 2 weight gain period was significantly extended by XRT-IUDR treatment in the rats with intraparenchymal tumors. The third and final phase consisted of a period of irreversible weight loss which may be related to cachexia. The third phase was similar in duration for control, XRT, IUDR and XRT-IUDR groups of rats and had a mean length of 9.8 +/- 0.27 days.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reduced levels of histone H3 acetylation on the inactive X chromosome in human females

Novel antibodies were generated that are highly selective for either acetylated or unacetylated iso-forms of histone H3, or the acetylated form of histone H4 in organisms as diverse asTetrahymena and humans. Using these antibodies as pair-wise sets in immunocytological analyses, we demonstrate that the inactive X chromosome is hypoacetylated for both histone H3 and H4 in female mammalian cells, whereas the antibody that recognizes the unacetylated form of histone H3 identifies all chromosomes uniformly. These data verify and extend previous results and suggest that hypoacetylation of core histones may be a general feature of the chromatin along the inactive X chromosome. Edited by: D. Bazett-Jones     

Immune lysis of reconstituted myelin basic protein--lipid vesicles and myelin vesicles

Complement-mediated lysis of reconstituted lipid-myelin basic protein (BP) vesicles and myelin vesicles due to antibody raised against BP and isolated myelin is measured by determination of the amount of a water-soluble spin label, tempocholine chloride, released from the vesicles. The response is shown to be antigen-specific, antibody-dependent, and complement mediated. The relative response to different anti-BP antibody samples is similar to that determined by radioimmunoassay procedures. In contrast to immunoassays with BP in aqueous solution, this method measures immune recognition of the protein in either a synthetic or a natural membranous environment. This is important because this protein has been shown to have a different conformation when bound to lipid bilayers than in aqueous solution and its conformation depends on lipid composition. It is also a more rapid method because no separation of spin label still trapped in the vesicles and that released due to immune lysis is required. In synthetic membranes consisting of sphingomyelin, cholesterol, and an acidic lipid, either phosphatidylglycerol, phosphatidic acid, or phosphatidylserine, the response was greatest when the acidic lipid was phosphatidic acid. The response did not depend significantly on the antigen concentration expressed as molar ratio of BP to sphingomyelin, over the range 0.15:600 to 2:600, although it decreased at molar ratios less than 0.15:600. The antigen density required for immune lysis of vesicles containing this protein antigen is similar to that reported elsewhere for lipid antigens, although the time required for maximal lysis was greater. Both anti-BP and anti-myelin antibodies caused a greater specific complement-mediated response with synthetic vesicles than with myelin vesicles, which may be due to the different lipid and/or protein composition of myelin. Response was also obtained with the myelin vesicles, however, indicating that some determinants of BP can be recognized on the surface of the bilayer in isolated myelin by anti-BP.     

Interaction of glycosylated human myelin basic protein with lipid bilayers

Myelin basic protein (MBP), isolated from normal human myelin, was glycosylated with UDP-N-acetyl-D-galactosamine and a glycosyltransferase isolated from porcine submaxillary glands. MBP containing 0.85 mol of N-acetyl-D-galactosamine per mole of protein was oxidized at carbon 6 by galactose oxidase and complexed with a spin-label, Tempoamine, in order to study its interactions with lipids. When the spin-labeled MBP was reacted with lipid vesicles consisting of DSPG, DPPG, and DMPG, most of the spin-label was motionally restricted in the gel phase, with a correlation time greater than 10(-8)s. The motion increased with increasing temperature and was sensitive to the lipid phase transition. Interaction with the gel phase of DPPA caused much less motional restriction of the probe. However, melting of the lipid allowed increased interaction and motional restriction of the probe, which was only partially reversed on cooling back to the gel phase. The motional restriction of the probe in these lipids is attributed to its penetration partway into the lipid bilayer in both the gel and liquid-crystalline phases. The fact that the probe bound to the protein can penetrate partway into the bilayer suggests that other hydrophobic side chains and residues of the protein can similarly penetrate into the bilayer. Additional evidence for penetration was provided by digestion of the lipid-bound protein with endoproteinase Lys-C. When nonglycosylated and glycosylated MBP in solution was treated with Lys-C, extensive digestion occurred. A single radioactive peptide which eluted at 25 min was identified as residues 92-105.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of membrane structure,osmotic fragility,and morphology of multiple sclerosis and normal erythrocytes

Erythrocyte membranes from multiple sclerosis (MS) patients and normal individuals were studied by electron spin resonance spectroscopy, osmotic fragility tests, scanning electron microscopy (SEM) and fatty acid analysis of membrane lipids. There was no significant difference in the membrane fluidity between MS and normal erythrocytes using fatty acid spin labels with the nitroxide moiety on carbons 5, 12, or 16 from the carboxyl group. Linoleic acid, which has been reported to decrease the absolute electrophoretic mobility of only MS erythrocytes, increased the fluidity of MS and normal erythrocyte membranes to a similar extent. The osmotic fragility of MS erythrocytes obtained from outpatients was similar to normal control cells but the osmotic fragility of erythrocytes obtained from hospitalized MS patients was greater than normal. Scanning electron microscopy of MS erythrocytes revealed no gross abnormalities. Cells incubated with linoleic acid had transformed from discocytes into sphero-echinocytes with prominent membrane surface indentations but MS and normal erythrocytes appeared identical. Of the fatty acid content of the total lipid extract, erythrocytes from most, but not all, MS hospitalized patients and some patients with other demyelinating diseases had relatively less (P<.001) 18:2 than the normal cells. These results indicate that at least some of the abnormalities reported in MS erythrocytes may only be found in hospitalized patients and may be due to other complications of the disease. They also indicate that the reported abnormal effects of linoleic acid on the electrophoretic mobility of MS erythrocytes may be caused by some other mechanism than an effect on the fluidity of the bilayer.     

An effect of colchicine on galactosyl- and sialyltransferases of rat liver Golgi membranes

Colchicine inhibited the activity of the galactosyl- and sialyltransferases of rat liver Golgi membranes. The sialyltransferase was more sensitive to the drug than galactosyltransferase since it was inhibited to a greater extent and at lower concentrations of colchicine than the galactosyltransferase. Two soluble enzymes, i.e. that from rat serum and that isolated from bovine milk, were not inhibited by colchicine. Even with very high concentrations of colchicine a marked stimulation of activity was observed. The data suggest that the inhibition observed in the Golgi membranes is in some way related to the arrangement of the enzymes in the lipid bilayer. In support of this hypothesis, the milk galactosyltransferase became very sensitive to colchicine after incorporation of the enzyme into lipid vesicles. The incorporation of colchicine into Golgi membranes was shown to decrease the order parameter as determined by electron spin resonance which reflects an increased fluidity of the Golgi membranes. A change in fluidity may be responsible for the inhibition of enzyme activity at least in part.     

Population structure of pierid butterflies IV. Genetic and physiological investment in offspring by male Colias

Summary Population structure encompasses all the rules by which a population's gametes come together, including genetic and physiological investment in offspring. We document female use of nutrients donated by males at mating, and complete sperm precedence, in Colias eurytheme Boisduval. The effect of these phenomena on the population structure of this species is discussed.