RESUMO
The magnitude and temperature dependence of most of the properties of amorphous solids are anomalous at very low temperatures ( less, similar1 Kelvin). Phonon-assisted tunneling of a distribution of glassy bistable configurations, or two-level systems, can account for these anomalies. A unified understanding of the low-temperature properties is required for an understanding of the glassy state. Persistent nonphotochemical hole burning of impurity optical transitions allows a glass state to be produced that is thermally inaccessible to the preburn state, and that allows the probing of tunneling dynamics on time scales that range between picoseconds and days. These data combined with recently obtained distribution functions for the two-level systems offer new insights into the tunneling dynamics.
RESUMO
Chronic endobronchial infection with mucoid Pseudomonas aeruginosa accounts for much of the morbidity and mortality in patients with cystic fibrosis (CF). Reduced morbidity is observed when infection is absent. Clinical investigations have implicated opsonizing antibody specific for the mucoid exopolysaccharide (MEP) surrounding these bacteria as a potential immunologic protective mechanism, whereas nonopsonizing antibody to MEP is not protective. Mice and rats immunized with doses of MEP that elicited opsonizing antibody had reduced levels of infection compared with nonimmune controls after intratracheal challenge with mucoid P. aeruginosa enmeshed in agar beads. Doses of MEP that elicited nonopsonizing antibody were not protective. Parallel experiments in which passive transfer of polyclonal and monoclonal opsonizing and nonopsonizing antibody were used yielded similar results. These data indicate that MEP-specific opsonizing antibody can protect against chronic P. aeruginosa infection in this model of disease.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Polissacarídeos Bacterianos/imunologia , Infecções por Pseudomonas/imunologia , Animais , Fibrose Cística/complicações , Modelos Animais de Doenças , Feminino , Imunização Passiva , Pulmão/patologia , Infecções por Pseudomonas/patologia , Infecções por Pseudomonas/prevenção & controle , Pseudomonas aeruginosa/imunologia , RatosRESUMO
Structural modification of photosynthetic reaction centers is an important approach for understanding their charge-separation processes. An unprecedented persistent structural transformation of the special pair (dimer) of bacteriochlorophyll molecules can be produced by light absorption alone. The nonphotochemical hole-burned spectra for the reaction center of Rhodopseudomonas viridis show that the phototransformation leads to a red shift of 150 wave numbers for the special pair's lowest energy absorption band, P960, and a comparable blue shift for a state at 850 nanometers, which can now be definitively assigned as being most closely associated with the upper dimer component. Additional insights on excited-state electronic structure include the identification of a new state.
RESUMO
The laser excited fluorescence-line-narrowed spectrum of DNA modified with (+/-)-r-7,t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE), the ultimate carcinogenic metabolite of benzo[a]pyrene (BP), has been obtained in a water-glycerol-ethanol glass at 4.2 K. The spectrum was well resolved and highly characteristic of the chromophore. Comparisons were made between the spectrum of this modified DNA and the isolated deoxyguanosine-BPDE adduct and a series of other 7,8,9,10-tetrahydro-BP (THBP) derivatives. 9-Hydroxy-BP 4,5-oxide, which is also involved in the binding of BP to DNA, and THBP have very similar conventional broadband fluorescence spectra. However, the fluorescence-line-narrowed spectra of their derivatives were readily distinguishable either as individual components or as mixtures.
Assuntos
Benzopirenos/metabolismo , Carcinógenos/metabolismo , DNA/metabolismo , Di-Hidroxi-Di-Hidrobenzopirenos , Espectrometria de Fluorescência , 7,8-Di-Hidro-7,8-Di-Hidroxibenzo(a)pireno 9,10-óxido , Desoxiguanosina/análogos & derivadosRESUMO
The major insecticide resistance mechanism in the brown planthopper Nilaparvata lugens involves overproduction of esterases. Esterases purified from a resistant strain appeared as a ladder of bands on isoelectric focussing (IEF) gels from pI 4.7 to 5.0. Two-dimensional electrophoresis showed that isozymes ranged in size from 66 to 68 kDa with those of lower pI being apparently smaller. All isozymes detected by two-dimensional electrophoresis were glycosylated. N-glycosidase A reduced the number of isozymes on IEF to two, with increased pI and an increased molecular weight of 69 kDa. No O-linked glycans were detected. Deglycosylation had no effect on esterase activity, hence glycosylation is not involved in active site conformation. As N-glycosidase F completely deglycosylated the esterases, none of the glycans has an alpha1,3-bound core fucose. Reactivity with the lectins GNA, MAA and DSA, combined with differential cleavage of N-linked glycans with endoglycosidases F1 and F2, indicated that terminally linked mannose is present in high mannose and/or hybrid type glycans and that terminally linked sialic acid and galactose-beta(1-4)-N-acetylglucosamine are present in biantennary complexes. Neuraminidase treatment had the same effect on pI of isozymes as complete deglycosylation. Therefore, the majority of the heterogeneity of elevated esterases on IEF is due to differential attachment of sialic acid to glycans of the two proteins.
Assuntos
Esterases/metabolismo , Insetos/enzimologia , Animais , Esterases/isolamento & purificação , Glicosilação , Resistência a Inseticidas , Ponto Isoelétrico , Isoenzimas/isolamento & purificação , Isoenzimas/metabolismo , Polissacarídeos/metabolismo , Ácidos Siálicos/metabolismoRESUMO
Using polyacrylamide gel electrophoresis (PAGE) and low-temperature, laser-induced fluorescence line narrowing (FLN) and non-line narrowing (NLN) spectroscopic methods, the conformational characteristics of stereochemically defined and site-specific adducts derived from the binding of 7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene (anti-BPDE, a metabolite of the environmental carcinogen benzo[a]pyrene), to DNA were studied. The focus of these studies was on the four stereochemically distinct anti-BPDE modified duplexes 5'-d(CCATCGCTACC).(GGTAGCGATGG), where G denotes the lesion site derived from trans or cis addition of the exocyclic amino group of guanine to the C10 position of either (+) or (-)-anti-BPDE. PAGE experiments under non-denaturing conditions showed that the (+)-trans adduct causes a significantly greater retardation in the electrophoretic mobility than the other three adducts, probably the result of important adduct-induced distortions of the duplex structure. Low-temperature fluorescence studies in frozen aqueous buffer matrices showed that the (+)-trans adduct adopts primarily an external conformation with only minor interactions with the helix, but a smaller fraction (approximately 25%) appears to exists in a partially base-stacked conformation. The (-)-trans adduct exists almost exclusively (approximately 97%) in an external conformation. Both cis adducts were found to be intercalated; strong electron-phonon coupling observed in their FLN spectra provided additional evidence for significant pi-pi stacking interactions between the pyrenyl residues and the bases. FLN spectroscopy is shown to be suitable for distinguishing between trans and cis adducts, but lesions with either (+)- or (-)-trans, or (+)- or (-)-cis stereochemical characteristics showed very similar vibrational patterns.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Benzo(a)pireno/química , Benzopirenos/química , Adutos de DNA/química , Sequência de Bases , Fenômenos Biofísicos , Biofísica , Fenômenos Químicos , Físico-Química , Conformação Molecular , Dados de Sequência Molecular , Estrutura Molecular , Oligonucleotídeos/química , Espectrometria de Fluorescência , Estereoisomerismo , TemperaturaRESUMO
Low-temperature absorption, fluorescence and persistent non-photochemical hole-burned spectra are reported for the CP29 chlorophyll (Chl) a/b antenna complex of photosystem II of green plants. The absorption-origin band of the lowest Qy-state lies at 678.2 nm and carries a width of approximately 130 cm-1 that is dominated by inhomogeneous broadening at low temperatures. Its absorption intensity is equivalent to that of one of the six Chl a molecules of CP29. The absence of a significant satellite hole structure produced by hole burning, within the absorption band of the lowest state, indicates that the associated Chl a molecule is weakly coupled to the other Chl and, therefore, that the lowest-energy state is highly localized on a single Chl a molecule. The electron-phonon coupling of the 678.2 nm state is weak with a Huang-Rhys factor S of 0.5 and a peak phonon frequency (omega m) of approximately 20 cm-1. These values give a Stokes shift (2S omega m) in good agreement with the measured positions of the absorption band at 678.2 nm and a fluorescence-origin band at 679.1 nm. Zero-phonon holes associated with the lowest state have a width of approximately 0.05 cm-1 at 4.2 K, corresponding to a total effective dephasing time of approximately 400 ps. The temperature dependence of the zero-phonon holewidth indicates that this time constant is dominated at temperatures below 8 K by pure dephasing/spectral diffusion due to coupling of the optical transition to the glass-like two-level systems of the protein. Zero-phonon hole-widths obtained for the Chl b bands at 638.5 and 650.0 nm, at 4.2 K, lead to lower limits of 900 +/- 150 fs and 4.2 +/- 0.3 ps, respectively, for the Chl b-->Chl a energy-transfer times. Downward energy transfer from the Chl a state(s) at 665.0 nm occurs in 5.3 +/- 0.6 ps at 4.2 K.
Assuntos
Complexo de Proteínas do Centro de Reação Fotossintética/química , Spinacia oleracea/química , Complexos de Proteínas Captadores de Luz , Complexo de Proteína do Fotossistema IIRESUMO
Capillary electrophoresis (CE) interfaced with low-temperature (4.2 K) fluorescence line-narrowing spectroscopy (FLNS) is used for the separation and spectral characterization of closely related analytes. In this paper, the CE-FLNS system is applied to the analysis of a mixture of deuterated and protonated benzo[a]pyrene, a mixture of structurally similar benzo[a]pyrene and benzo[e]pyrene, and mixtures of dibenzo[a,l]pyrene-derived adenine DNA adducts. The CE-FLNS system provides on-line separation and high-resolution spectroscopic identification of CE-separated analytes, via fingerprint structure of vibrationally resolved FLN spectra at 4.2 K. The combination of the separation power of CE and the spectral selectivity of FLNS provide a methodology that has potential to become a powerful tool for molecular analyte characterization. The main applications of the CE-FLNS system, due to its selectivity, should be in the chemical analysis of structurally similar analytes and applications where analyte purity and detailed structural characterization are required.
Assuntos
Benzopirenos/análise , Adutos de DNA/análise , Eletroforese Capilar/métodos , Sistemas On-Line , Benzopirenos/química , Espectrometria de FluorescênciaRESUMO
A capillary electrophoretic method for the separation and on-line identification of closely related analytes using low-temperature fluorescence spectroscopy is reported for the eight diastereomeric deoxyadenosine (dA) adducts derived from dibenzo[a,l]pyrene diol epoxide (DB[a,l]PDE). Electrophoretic separation of stereoisomers was accomplished by application of a mixed surfactant buffer [dioctyl sulfosuccinate (DOSS) and Brij-S], which was below the critical micelle concentration (CMC) due to the high concentration (approximately 25%) of organic solvent. Addition of multiple surfactant additives to the separation buffer provided electrophoretic resolution, which was unattainable under single surfactant conditions. It is shown that the CE-separated analyte zones could be identified on-line via low-temperature (4.2 K) fluorescence non-line narrowing and fluorescence line-narrowing (FLN) spectroscopy. In addition, it was determined that in CE buffer trans-syn-,cis-syn- and cis-anti-DB[a,l]PDE-14-N6dA diastereomeric adducts exist mostly with the -dA and DB[a,l]P moiety in an "open"-type conformation while the trans-anti-DB[a,l]PDE-14-N6dA adducts exist in two different conformations whose relative distribution depends on matrix composition. The above conformations have also been revealed by selective laser excitation. Thus, the low-temperature methodology not only provides fingerprint structure via vibrationally resolved 4.2 K fluorescence spectra for adduct identification, but also provides conformational information on the spatial relationship of the carcinogen and dA moiety. These results, taken together with those for DB[a,l]P-DNA adducts formed in standard glasses and mouse epidermis exposed to DB[a,l]P, support our earlier findings that DB[a,l]P-derived adducts exist in different conformations [Jankowiak et al., Chem. Res. Toxicol. 11 (1998) 674]. Therefore, the combination of the separation power of CE and spectral selectivity of low-temperature fluorescence spectroscopy at NLN and FLN conditions provides a powerful methodology which should prove useful for identification of closely related DNA adducts formed at low levels in biological systems.
Assuntos
Benzopirenos/análise , Adutos de DNA/análise , Desoxiadenosinas/análise , Eletroforese Capilar/métodos , Compostos de Epóxi/análise , Soluções Tampão , Carcinógenos/análise , Desoxiadenosinas/química , Sistemas On-Line , Espectrometria de Fluorescência , Estereoisomerismo , TemperaturaRESUMO
Activation of the moderate carcinogen 6-methylbenzo[a]pyrene (6-CH(3)BP) by one-electron oxidation to form DNA adducts was studied. Iodine oxidation of 6-CH(3)BP in the presence of dGuo produces BP-6-CH(2)-N(2)dGuo, BP-6-CH(2)-N7Gua and a mixture of 6-CH(3)BP-(1&3)-N7Gua, whereas in the presence of Ade the adducts BP-6-CH(2)-N1Ade, BP-6-CH(2)-N3Ade, BP-6-CH(2)-N7Ade and 6-CH(3)BP-(1&3)-N1Ade are obtained. Furthermore, for the first time an aromatic hydrocarbon radical cation afforded an adduct with dThd, the stable adduct BP-6-CH(2)-N3dThd. Formation of these adducts indicates that the 6-CH(3)BP radical cation has charge localized at the 6, 1 and 3 position. When 6-CH(3)BP was activated by horseradish peroxidase in the presence of DNA, two depurinating adducts were identified, BP-6-CH(2)-N7Gua (48%) and 6-CH(3)BP-(1&3)-N7Gua (23%), with 29% unidentified stable adducts. In the binding of 6-CH(3)BP catalyzed by rat liver microsomes, the same two depurinating adducts, BP-6-CH(2)-N7Gua (22%) and 6-CH(3)BP-(1&3)-N7Gua (10%), were identified, with 68% unidentified stable adducts. In 6-CH(3)BP-treated mouse skin, the two depurinating adducts, BP-6-CH(2)-N7Gua and 6-CH(3)BP-(1&3)-N7Gua, were identified. Although quantitation of these two adducts was not possible due to coelution of metabolites on HPLC, they appeared to be the major adducts found in mouse skin. These results show that 6-CH(3)BP forms depurinating adducts only with the guanine base of DNA, both in vitro and in mouse skin. The weaker reactivity of 6-CH(3)BP radical cation vs. BP radical cation could account for the weaker tumor-initiating activity of 6-CH(3)BP in comparison to that of BP.
Assuntos
Benzopirenos/química , Carcinógenos/química , Adutos de DNA/química , Desoxirribonucleotídeos/química , Adenina/química , Adenina/metabolismo , Animais , Benzopirenos/metabolismo , Biotransformação , Carcinógenos/metabolismo , Bovinos , Adutos de DNA/biossíntese , Adutos de DNA/síntese química , Desoxirribonucleotídeos/metabolismo , Feminino , Guanina/química , Guanina/metabolismo , Iodo/química , Camundongos , Oxirredução , Pele/química , Pele/efeitos dos fármacos , Pele/metabolismo , Espectrometria de Massas de Bombardeamento Rápido de ÁtomosRESUMO
A recent paper (D. Bolton and J.D. Winefordner, Talanta, 1983,30,9) on the analytical utility of laser-excited fluorescence line-narrowing is critically assessed.
RESUMO
An important initiating step in the induction of tumors is believed to be the covalent binding of an active carcinogenic species to a cellular macromolecule, e.g. DNA. Therefore, a spectroscopic technique which allows for positive identification of the intact (macromolecular) DNA adduct and/or isolated damaged nucleosides/nucleotides is highly desirable. It is shown that fluorescence line-narrowing spectroscopy (FLNS) is a rapid, versatile, highly sensitive and selective analytical technique, which can be used directly to characterize DNA adducts and isolated nucleosides. FLNS possesses sufficient resolution to distinguish between the major DNA adducts derived from different enantiomers of benzo[a]pyrene diol-epoxide (BPDE). With the present limit of detection (approximately 1 adducted base per 10(8) normal base pairs for 100 micrograms of DNA), the technique is applicable to in vivo samples. Analysis of liver DNA from fish exposed to benzo[a]pyrene (BP) (100 mg BP/kg fish) showed that a major DNA adduct is derived from syn-BPDE.
Assuntos
7,8-Di-Hidro-7,8-Di-Hidroxibenzo(a)pireno 9,10-óxido/análise , 7,8-Di-Hidro-7,8-Di-Hidroxibenzo(a)pireno 9,10-óxido/metabolismo , Carcinógenos/metabolismo , Adutos de DNA , DNA/análise , DNA/metabolismo , Espectrometria de Fluorescência , EstereoisomerismoRESUMO
The resistance status of 14 strains of Blattella germanica (L.) from four countries was determined for chlorpyrifos and propoxur compared with a standard reference susceptible strain. Thirteen strains were resistant to chlorpyrifos; 12 strains were resistant to propoxur. Resistance ratios for chlorpyrifos ranged from 8- to 462-fold at LC90; for propoxur, resistance ratios ranged from 4- to 46-fold. One cockroach strain from Denmark had negative cross-resistance to chlorpyrifos, and one strain from the United States had negative cross-resistance to propoxur. Slopes of probit regressions indicated that all resistant strains were heterogeneous for resistance to both chlorpyrifos and propoxur. Synergist studies with piperonyl butoxide indicated that multifunction mono-oxidases are probably involved in resistance to chlorpyrifos in six strains and in resistance to propoxur in seven strains. Esterase activity was elevated in 10 strains; of these strains, two had only slightly elevated esterase activity as measured with the substrates 1- and 2-naphthyl acetate. The remainder had higher levels of elevated esterase activity to both substrates. Strains with elevated esterase activity were resistant to a broad spectrum of organophosphates, pyrethroids, or both. Increased levels of glutathione S-transferase activity were found in four strains. Another two strains had a low frequency (1%) of individuals with high glutathione S-transferase activity. Elevated glutathione S-transferase activity was not correlated with the observed levels of organophosphate or carbamate resistance. One strain from Dubai had an altered acetylcholinesterase-based mechanism that conferred broad-spectrum resistance to a range of organophosphates and carbamates.
Assuntos
Clorpirifos/farmacologia , Baratas/enzimologia , Propoxur/farmacologia , Animais , Resistência a Inseticidas/fisiologiaRESUMO
Thirty strains of Blattella germanica (L.) reported to be pyrethroid resistant were collected from three continents. Greater than 2-fold resistance to the pyrethroids cyfluthrin, fenvalerate, cypermethrin, and lambda cyhalothrin appeared in 15 of these strains. Twelve of these strains were also resistant to chlorpyrifos and propoxur. All the field strains tested were heterogeneous with regard to resistance. Possible resistance mechanisms detected in these populations included elevated levels of cytochrome P450, general esterase and glutathione S-transferase, and nerve insensitivity (kdr-type resistance). The elevated esterases and oxidase-based resistance were the most prevalent; 11 and 10 strains, respectively, had evidence of these mechanisms. Resistance was synergized by piperonyl butoxide in some strains. In some strains, elevated esterases, although present, were primarily correlated with organophosphate resistance. Pyrethroid insecticides may still be effective against many of these populations because of the low levels of resistance detected. However, potential exists for more serious resistance problems to develop if only pyrethroids are used. Because many of these strains are already resistant to organophosphorus and carbamate insecticides, prospects for the future chemical control of these populations must be carefully considered.
Assuntos
Baratas/metabolismo , Piretrinas/farmacologia , Animais , Resistência a Inseticidas/fisiologia , MasculinoRESUMO
Widespread resistance to organophosphorus insecticides (OPs) in Nilaparvata lugens is associated with elevation of carboxylesterase activity. A cDNA encoding a carboxylesterase, Nl-EST1, has been isolated from an OP-resistant Sri Lankan strain of N. lugens. The full-length cDNA codes for a 547-amino acid protein with high homology to other esterases/lipases. Nl-EST1 has an N-terminal hydrophobic signal peptide sequence of 24 amino acids which suggests that the mature protein is secreted from cells expressing it. The nucleotide sequence of the homologue of Nl-EST1 in an OP-susceptible, low esterase Sri Lankan strain of N. lugens is identical to Nl-EST1. Southern analysis of genomic DNA from the Sri Lankan OP-resistant and susceptible strains suggests that Nl-EST1 is amplified in the resistant strain. Therefore, resistance to OPs in the Sri Lankan strain is through amplification of a gene identical to that found in the susceptible strain.
Assuntos
Hidrolases de Éster Carboxílico/genética , Hemípteros/enzimologia , Inseticidas/farmacologia , Compostos Organofosforados , Sequência de Aminoácidos , Animais , Carboxilesterase , DNA Complementar , Hemípteros/efeitos dos fármacos , Hemípteros/genética , Resistência a Inseticidas , Dados de Sequência Molecular , Alinhamento de SequênciaRESUMO
Studies were conducted in guinea pigs, myelosuppressed by cyclophosphamide, for determination of whether passive immune therapy for Pseudomonas aeruginosa pneumonia would be useful in the setting of neutropenia. Groups of infected animals (14 per group) were treated with a single intravenous infusion of hyperimmune IgG antibody to P. aeruginosa (PA-IGIV; 500 mg/kg), tobramycin (1.7 mg/kg per 8 hr), ticarcillin (120 mg/kg per 6 hr), or combinations of these regimens. Control groups received intravenous albumin solution. Survival rates were 0% with albumin only, 0% with PA-IGIV, 43% with tobramycin (P less than .05), 86% with tobramycin plus PA-IGIV (P less than .05 vs. tobramycin alone), 7% with ticarcillin, and 43% with ticarcillin plus PA-IGIV (.05 less than P less than .10 vs. ticarcillin alone). Additive intrapulmonary killing of P. aeruginosa and prevention of bacteremia were observed in animals treated with tobramycin plus PA-IGIV compared with either treatment alone. Thus, passive immune therapy for P. aeruginosa pneumonia may be useful in the neutropenic host, but only when used in conjunction with antimicrobial agents.
Assuntos
Agranulocitose/complicações , Imunização Passiva , Neutropenia/complicações , Pneumonia/terapia , Infecções por Pseudomonas/terapia , Pseudomonas aeruginosa/imunologia , Animais , Anticorpos Monoclonais/uso terapêutico , Quimioterapia Combinada , Cobaias , Pulmão/imunologia , Pulmão/microbiologia , Macrófagos , Neutrófilos , Pneumonia/complicações , Infecções por Pseudomonas/complicações , Sepse/prevenção & controle , Sepse/terapia , Ticarcilina/uso terapêutico , Tobramicina/uso terapêuticoRESUMO
Low temperature (4.2 K) absorption and hole burned spectra are reported for a stabilized preparation (no excess detergent) of the photosystem II reaction center complex. The complex was studied in glasses to which detergent had and had not been added. Triton X-100 (but not dodecyl maltoside) detergent was found to significantly affect the absorption and persistent hole spectra and to disrupt energy transfer from the accessory chlorophyll a to the active pheophytin a. However, Triton X-100 does not significantly affect the transient hole spectrum and lifetime (1.9 ps at 4.2 K) of the primary donor state, P680(*). Data are presented which indicate that the disruptive effects of Triton X-100 are not due to extraction of pigments from the reaction center, leaving structural perturbations as the most plausible explanation. In the absence of detergent the high resolution persistent hole spectra yield an energy transfer decay time for the accessory Chl a QY-state at 1.6 K of 12 ps, which is about three orders of magnitude longer than the corresponding time for the bacterial RC. In the presence of Triton X-100 the Chl a QY-state decay time is increased by at least a factor of 50.
RESUMO
The therapeutic activity of ciprofloxacin, enoxacin, and ofloxacin was evaluated in guinea pigs with acute and chronic experimental Pseudomonas aeruginosa pneumonia. Intratracheal instillations of P. aeruginosa resulted in fatal pneumonia in all untreated animals within 36 h. Among treatment groups (80 mg/kg [body weight] per day), cumulative survival rates were: 47%, ciprofloxacin; 55%, enoxacin; and 42%, ofloxacin. These rates were not significantly different. Intrapulmonary killing of P. aeruginosa was equivalent 3 h after a single dose of ciprofloxacin or ofloxacin (20 mg/kg) or enoxacin (40 mg/kg). The combination of ciprofloxacin with azlocillin, ceftazidime, or tobramycin did not increase the efficacy of intrapulmonary killing of P. aeruginosa over that of ciprofloxacin alone. A chronic, nonfatal bronchopneumonia was induced in guinea pigs by intratracheal instillation of microscopic agar beads impregnated with a mucoid strain of P. aeruginosa. Compared with no treatment, ciprofloxacin and enoxacin produced greater than or equal to 99.9% intrapulmonary killing, and ofloxacin sterilized the lungs completely, after 4 days of treatment. In no quinolone-treated animal did resistant strains of P. aeruginosa emerge during 4-day treatment periods. In further studies with the chronic model, oral and parenteral ciprofloxacin treatment were found to be equivalent in efficacy. We conclude that several quinolone derivatives may be effective for the treatment of P. aeruginosa pneumonia and that combinations of quinolones with beta-lactams or aminoglycosides may not increase efficacy against P. aeruginosa pneumonia.
Assuntos
Anti-Infecciosos/uso terapêutico , Pneumonia/tratamento farmacológico , Infecções por Pseudomonas/tratamento farmacológico , Animais , Anti-Infecciosos/sangue , Ciprofloxacina , Enoxacino , Cobaias , Cinética , Naftiridinas/sangue , Naftiridinas/uso terapêutico , Ofloxacino , Oxazinas/sangue , Oxazinas/uso terapêutico , Pneumonia/etiologia , Quinolinas/sangue , Quinolinas/uso terapêuticoRESUMO
Oxygen metabolism and calcium ion (Ca++) handling in blood monocytes were greatly affected by treatment with recombinant gamma interferon (rIFN-gamma). Incubating the monocytes with rIFN-gamma resulted in increased basal production of superoxide anion, as well as a significantly enhanced respiratory burst in response to concanavalin A (Con A). A concomitant increase in microbicidal activity against Listeria monocytogenes was observed, and cell membrane permeability to Ca++ was enhanced by treatment with rIFN-gamma. Con A stimulation was also associated with acute rises in cytosolic-free calcium, and these calcium transients were greatly augmented in cells pretreated with rIFN-gamma. The enhanced respiratory burst and the increased calcium transients were completely neutralized by a monoclonal antibody to rIFN-gamma. Furthermore, enhancement of the respiratory burst and calcium transients occurred in a parallel dose-response range for rIFN-gamma. Blocking the intracellular release of calcium into cytosol by TMB-8 abrogated the capacity of rIFN-gamma to enhance the monocyte respiratory burst. Thus, not only was rIFN-gamma treatment of monocytes associated with altered calcium metabolism, but calcium from intracellular pools was essential to the expression of this activated state during Con A stimulation.
Assuntos
Atividade Bactericida do Sangue , Cálcio/análise , Citosol/análise , Interferon gama/farmacologia , Monócitos/imunologia , Proteínas Recombinantes/farmacologia , Adesão Celular/efeitos dos fármacos , Permeabilidade da Membrana Celular , Concanavalina A/farmacologia , Relação Dose-Resposta a Droga , Ácido Gálico/análogos & derivados , Ácido Gálico/farmacologia , Humanos , Oxigênio/metabolismo , Consumo de Oxigênio/efeitos dos fármacos , Fagocitose/efeitos dos fármacos , Superóxidos/biossínteseRESUMO
The underlying principles of spectral hole burning spectroscopies and the theory for hole profiles are reviewed and illustrated with calculated spectra. The methodology by which the dependence of the overall hole profile on burn wavelength can be used to reveal the contributions from site inhomogeneous broadening and various homogeneous broadening contributions to the broad Qy-absorption bands of cofactors is emphasized. Applications to the primary electron donor states of the reaction centers of purple bacteria and Photosystems I and II of green plants are discussed. The antenna (light harvesting) complexes considered include B800-B850 and B875 of Rhodobacter sphaeroides and the base-plate complex of Prosthecochloris aestuarii with particular attention being given to excitonic interactions and level structure. The data presented show that spectral hole burning is a generally applicable low temperature approach for the study of excited state electronic and vibrational (intramolecular, phonon) structures, structural heterogeneity and excited state lifetimes.