Role of peridomestic birds in the transmission of St. Louis encephalitis virus in southern California.

In response to the 1984 St. Louis encephalitis (SLE) epidemic in the Los Angeles Basin of southern California (USA), an investigative program was initiated to evaluate the interactive components of the SLE virus transmission cycle. From 1987 through 1996 (10 yr), 52,589 birds were bled and their sera tested for SLE and western equine encephalomyelitis (WEE) virus antibodies by the hemagglutination inhibition (HAI) test. Eighty-three percent of the birds tested were house finches (Carpodacus mexicanus) (48.7%) and house sparrows (Passer domesticus) (34.6%); 1.1% of these birds were positive for SLE antibodies. Prevalence of WEE antibodies was negligible. The analysis of 5,481 sera from rock doves (Columbia livia) yielded 3.6% SLE positives and 0.4% WEE positives. Collection sites were maintained as study sites when identified as positive bird, mosquito, and SLE virus activity localities; others were abandoned. Serial serum samples from 7,749 banded house sparrows and 9,428 banded house finches from these selected sites demonstrated year-round SLE virus transmission. One location exhibited significant numbers of house finches undergoing annual SLE seroconversion and a number of seroconversion-reversion-reconversion sequences suggesting either viral reinfection from mosquitoes or recrudescence by latent virus. A proportion of both bird species also lived for longer than 1 yr, thus, increasing the possibility of virus carry-over from autumn to spring. Assessment of concurrently collected mosquitoes indicated no correlative association between mosquito populations and SLE seroconversion and reconversion. European house sparrows introduced in the 1800's may have provided a supplemental link to the existing SLE virus enzootic cycle involving endemic house finches. Meteorological factors are reviewed as possible important correlates of SLE epidemics. The house finch/house sparrow serosurveillance system is also evaluated for use as an "Early Warning" indicator of SLE virus activity.

[Equilibrium solubility of new potential drugs in water, 1-octanol and cyclohexane]. / Uj potenciális gyógyszervegyületek egyensúlyi oldhatósági vizsgálata vízben, 1-oktanolban és ciklohexánban.

A method was developed for the determinations of the exact value of isotherm solubility equilibrium of organic compounds in various solvents, that can be used as a standard operating procedure, too. It was used for the determination of equilibrium solubility data of twenty two new organic compounds in three solvents: water, 1-octanol and cyclohexane. The data of ten imidazo-quinazolone and twelve pyrido-quinazolone derivatives were compared with their chemical structures moreover within and between the structural and solvents series. It was proved, that these compounds are not ideal solutes, due to a specific interaction with the solvents which is constant for the imidazo-quinazolones, while it is randomly altering at the different pyrido-quinazolones. The octanol/water partitioning data were calculated using octanol and water solubility data, and those were compared with separately, accurately measured data obtained by the traditional shake-flask method. Our data support, that--as it can be found in most of the literature--at compounds which form special interaction with the solvent the partition coefficient cannot be calculated from the solubility data, and reversely the water solubility cannot be estimated using the determined partition coefficient and some correction factors. It was demonstrated, that the calculated partition coefficient can be biased randomly up to and order of magnitude, and in some cases even the tendency of those is false in a series.

[Correlation between the structures and physicochemical properties of chemotherapeutic fluoroquinolone agents]. / Osszefüggés kemoterápiás fluorokinolonok szerkezete és fiziko-kémiai tulajdonságai között.

The acid-base properties, the lipophilicity and the HPLC behaviour of nine antibacterial fluoroquinolone derivatives were studied to reveal relationship between these physico-chemical parameters and the chemical structure. Basicity of compounds with two proton-binding sites is depicted here in terms of protonation macro- and microconstants. The concentrations of microspecies (cation, zwitterion, neutral and anion) were calculated in the function of pH. The microspeciation of fluoroquinolones were used to derive relationship between the apparent and true octanol/water partition coefficients. An analysis of structure-chromatographic behaviour has been performed utilizing the retention values was determined in a chromatographic system methanol-aqueous phosphate buffer/ODS. Close correlation was found between the lipophilicity and chromatographic behaviour of the tested compounds when pH dependence and the influence of an ionpairing agent were investigated.

Relationship between partitioning properties and (calculated) molecular surface. SPR investigation of imidazoquinazolone derivatives.

Structure-property relationship (SPR) investigations have been carried out for a series of N-bridged compounds synthetized recently as potential antithrombotic agents. The octanol/water partition coefficient and reversed phase HPLC retention (log k') were determined experimentally for ten imidazoquinazolone derivatives. Calculations including total geometry optimization and surface area have been carried out. The isotropic surface area (ISA) of supermolecules were obtained. The good correlations were found between log P, log k' and ISA values, provide simple and reliable means by using a single structural parameter for the log P prediction of polycyclic N-bridged compounds.

[Preliminary study on the presence of arbovirus in the populations of Corrientes and Misiones]. / Estudio preliminar sobre la presencia de arbovirus en poblaciones de Corrientes y Misiones.

Human seroprevalence of Flavivirus was determined by hemagglutination inhibition tests on 479 sera from Misiones and 49 from Corrientes provinces. Paraná and Uruguay river bank communities from Argentina and neighbouring countries carry out frequent traffic across the rivers. With the aim of searching for a possible introduction of Dengue virus from Brasil or/and Paraguay, reactivity among people from Paraná and Uruguay river communities was compared with those from mountain communities. Two sera from Ituzaingó (Corrientes Province) were positive for Dengue 2. In Misiones, 3 sera from Oberá and 2 from Montecarlo were reactive for Dengue 2 and 1 serum from Puerto Iguazú was reactive for Dengue 1. Seroprevalence among the river population was significatively higher than among the mountain population. Likewise, populations on Paraná river showed more positive sera than those on Uruguay river; 54% of the samples possessed titers for SLE virus higher than for Dengue or Yellow fever. Anti-alphavirus (EEE and WEE) antibodies tested in sera from Misiones people showed a complementary distribution pattern to flavivirus. Seroprevalence of anti-alphavirus antibodies was higher in the mountain than in the river populations.

Estudio preliminar sobre la presencia de arbovirus en poblaciones de Corrientes y Misiones. / [Preliminary study on the presence of arbovirus in the populations of Corrientes and Misiones]

Human seroprevalence of Flavivirus was determined by hemagglutination inhibition tests on 479 sera from Misiones and 49 from Corrientes provinces. Paraná and Uruguay river bank communities from Argentina and neighbouring countries carry out frequent traffic across the rivers. With the aim of searching for a possible introduction of Dengue virus from Brasil or/and Paraguay, reactivity among people from Paraná and Uruguay river communities was compared with those from mountain communities. Two sera from Ituzaingó (Corrientes Province) were positive for Dengue 2. In Misiones, 3 sera from Oberá and 2 from Montecarlo were reactive for Dengue 2 and 1 serum from Puerto Iguazú was reactive for Dengue 1. Seroprevalence among the river population was significatively higher than among the mountain population. Likewise, populations on Paraná river showed more positive sera than those on Uruguay river; 54

of the samples possessed titers for SLE virus higher than for Dengue or Yellow fever. Anti-alphavirus (EEE and WEE) antibodies tested in sera from Misiones people showed a complementary distribution pattern to flavivirus. Seroprevalence of anti-alphavirus antibodies was higher in the mountain than in the river populations.

[Hydrophobic constant values (delta RMO) of functional groups. II. Interpretation of fragment interactions]. / Funkciós csoportok hidrofób konstans értékeinek (delta RM0) vizsgálata. II. Fragmens interakciók értelmezése.

The delta RM0(-CH2-) values have been calculated from fragment values of various alkyl groups (methyl, ethyl, n-propyl). On the basis of delta RM0(-CH2-) values it has been established that the value of the so-called "second" methyl group from aromatic ring has slightly differed from that of the so-called third methylene group and the value of methylene functional group is constant independently from positions of substituents and from electronic interactions. The delta RM0 Me values of methyl group--which is directly attached to aromatic ring--have been regarded as the so-called first methylene group from aromatic ring since value of free energy needed for transfer of methyl group as well as the other physico-chemical data (mole volume, parachor) are nearly the same as those of methylene group according to the literature. Fragment values of methyl groups substituted at various positions have been compared to relating delta RM0(-CH2-) value which is free practically from electronic interactions and it has been ascertained that fragment values have been higher as well as lower. In accordance with literature lower delta RM0 Me values have been interpreted with hyperconjugation effect of aromatic system. On the other hand lower methylene fragment values of alkyl substituted compounds at N1 atom have been attributed to sigma conjugation. In literature higher delta RM0 Me values than relating delta RM0(-CH2-) value are known only in case of orto position to another functional group or by a methyl group on a sterically hindered aromatic ring. Results of tests have shown that values of delta RM0 Me can substantially increase with extension of conjugated aromatic system or with simultaneous substitutions of methyl, methylene groups, respectively at certain locations. The authors have assigned that increase to change of solvate cuver which surrounds the molecule. The same has been manifested by methyl fragment values of quinazoline derivates (tetrahydropyrroloquinazoline, hexahydroazepinoquinazoline) of different electronic distributions. On basis of calculations it has been proved that delta RM0 2-Me and delta RM0 6-Me fragment values of monosubstituted pyrido (1,2-a)-pyrimidine (PP) derivatives have significantly differed from delta RM0 Me values of at other positions (3,7,8,9) methyl substituted compounds. Among disubstituted derivatives only delta RM0 7-Me and delta RM0 8-Me values of 2-phenyl- and 3-carbetoxymethyl-PP derivatives have not differed from each other but methyl fragment values of other positions (6,9) have significantly differed from each other and from other fragment values too.(ABSTRACT TRUNCATED AT 400 WORDS)

[Hydrophobic constant values (delta RM0) of functional groups. I. Comparative study of delta RM0 values determined in open (TLC) and closed (OPTLC) chromatographic systems]. / Funkciós csoportok hidrofób konstans értékeinek (delta RM0) vizsgálata. I. Nyílt (TLC) és zárt (OPTLC) kromatográfiás rendszerben meghatározott delta RM0 értékék összehasonlító vizsgálata.

delta RM0 values of functional groups (methyl, ethyl, n-propyl, methylene, phenyl, benzyl, saturation) of nitrogen bridgehead compounds [PP = pyrido(1,2-a)-pyrimidine, THPP = tetrahydropyrido(1,2-a)-pyrimidine, CTM-PP = 2,3-cyclotrimethylpyrido(1,2-a)-pyrimidine, CTM-THPP = 2,3-cyclotrimethylenetetrahydropyrido(1,2-a)-pyrimidine, CTRM-PP = 2,3-cyclotetramethylenepyrido(1,2-a)-pyrimidine, CTRM-THPP = 2,3-cyclotetramethylene-tetrahydropyrido(1,2-a)-pyrimidine, CTRM-THPP = 2,3-cyclotetramethylene-tetrahydropyrido(1,2-a)-pyrimidine, THPQ = tetrahydropyrroloquinazoline-, HHAQ = hexahydroazepinoquinazoline-derivates have been calculated from difference of retention values measured on RP-di-C1 stationary phase using methanol + water mobile phases of 6 (10 respectively) various compositions and of retention values (RM0) extrapolated to 0% organic phase. Retention data have been determined in normal chambers loaded with change of phase rate because of the vapour space of the developing chamber and in so-called pressurized ultramicro chamber which is free of change of phase rate and that of vapour space, respectively. It has been ascertained that delta RM0 values of same functional groups--that had been measured in the two different chamber systems--have not significantly differ from each other. It has also been established that opposite direction distortions of RM0 values--measured in normal chambers with mobile phases nearing or moving off 0% organic phase--have generally similar effects on delta RM0 values which are free of change of phase rate. Significant investigations were carried out by programs written on TEXAS SR-52 computer and work has always been done in 95% confidence interval.

[Ion exchange interactions on silica gel layers. II. Halogen salts of compounds containing organic tertiary and quaternary nitrogen]. / Szilikagél rétegen végbemenö ioncserés kölcsönhatások. II. Szerves tercier és kvaterner nitrogént vegyületek haloidsói.

Primary and secondary ion exchanges--of hydrochloric acid and hydrobromic acid salts of well hydrolyzing organic bases as well as quaternary ammonium bromide which are important drug substance--taking place on silica gel using methanol as mobile phase have been investigated by thin-layer chromatographic and spectrophotometric methods. In case of tertiary ammonium salts (hydrolyzing salts) basis linked to silanate ion and halogen acid have been formed by primary ion exchange. During secondary ion exchange halogen acid has exchanged metal ions linked to silanate ions on the layer. In case of non hydrolyzing salts, the quaternary ammonium bromide salts it could not surely be proved by the applied methods whether primary ion exchange had been followed by secondary ion exchange or only primary ion exchange had occurred.

[Ion exchange interactions on silica gel layers. III. Salts of organic bases with organic acids. Organic acids and sodium salts]. / Szilikagél rétegen vébemenö ioncserés kölcsönhatások. III. Szerves bázisok szerves savakkal alkotott sói. Szerves savak és nátriumsók.

By thin-layer chromatographic and spectroscopic (UV, IR) methods it has been proved that bass and acid are formed from salts of organic bases with organic acids during primary interaction because of the ion exchange behaviour of the silica gel layer. The organic acids formed have interacted with metals on the layer during secondary ion exchange and they migrate further as salts again. It has also been established that the extent of secondary ion exchange between metal silanate groups and acids depends on pKS values of acids. On the basis of investigations it can be ascertained with great probability that organic acids of pKS greater than 7 do not interact with metal silanate groups of silica gel layer. Sodium salts of organic acids of pKS less than 3 values similarly do not interact on the other hand sodium salts of organic acids of pKS greater than 3 values are able to interact with silanol groups. It has been established by flame atomic emission method that salicylic acid interacts with sodium ion and 86% of it migrates further as sodium salicylate.

Antibody prevalence of St. Louis encephalitis virus in avian hosts in Los Angeles, California, 1986.

A study was conducted to determine the pattern of St. Louis encephalitis (SLE) virus activity in the avian populations of the Los Angeles metropolitan area in 1986. In total, 679 birds of 42 species were captured at 7 study sites. The overall prevalence of SLE neutralizing (N) antibody of 3% indicated enzootic transmission. Antibody prevalences were higher in birds sampled in the central part of the metropolitan area, which was consistent with other epidemiologic data. The use of specific avian species as sentinels for future surveillance of SLE virus activity was suggested.

Detection of St. Louis encephalitis virus antigen in mosquitoes by capture enzyme immunoassay.

Surveillance methods that measure St. Louis encephalitis (SLE) virus activity in nature may provide forewarning of its epidemic occurrence in humans. An antigen capture enzyme immunoassay was developed to detect SLE virus in infected mosquitoes. The assay detected purified SLE viral antigen at a concentration of 62 pg/0.1 ml when antigen was incubated overnight; 250 pg/0.1 ml was detected in a single-day assay (antigen incubated for 3 h). The assay detected 67.9 and 70.8% of laboratory-prepared pools of infected mosquitoes after 3 h and overnight incubation, respectively. The sensitivity of the procedure was 90.5% in identifying pools with infectious titers greater than dex 3.0. The specificity of the assay was controlled by retesting positive pools preincubated with SLE virus and normal antibodies, which led to a diminution of signal in the pools containing viral antigen. The procedure was suitably specific in discriminating between SLE and related flaviviruses, detecting only high infectious doses of heterologous antigens.