bluuebunny/crossref_metadata_2025 huggingface dataset:
Hypertension favors the inflammatory process in rats with experimentally induced periodontitis
Authors: Bonato C. F. , do‐Amaral C. C. F. , Belini L. , Salzedas L. M. P. , Oliveira S. H. P.
Published: June 2012

Bonato CF, do‐Amaral CCF, Belini L, Salzedas LMP, Oliveira SHP. Hypertension favors the inflammatory process in rats with experimentally induced periodontitis. J Periodont Res 2012; 47: 783–792. © 2012 John Wiley & Sons A/S

Background and Objective:  Cardiovascular diseases are significantly correlated with chronic periodontitis. The aim of this study was to evaluate bone‐loss level, neutrophil migration, CXCL2/CINC‐2α, CXCL5/LIX, CCL20/MIP‐3α and tumor necrosis factor‐α (TNF‐α) production, inducible nitric oxide synthase (iNOS) expression and C‐reactive protein (CRP) release in spontaneously hypertensive rats (SHRs) and normotensive (WTK) rats after experimental induction of periodontal disease.

Material and Methods:  Periodontitis was induced by placement of silk yarn ligatures around the first molar counterparts. The levels of CRP, CCL20/MIP‐3α and CXCL5/LIX were evaluated in the peripheral blood, and bone‐loss level, neutrophil recruitment, the production of myeloperoxidase, CXCL2, CXCL5, CCL20 and TNF‐α, and the expression of iNOS were evaluated in the gingival tissue. Histological sections were taken to evaluate and measure bone resorption and neutrophil recruitment in the furcation region.

Results:  Rats with periodontitis had alveolar bone resorption. SHRs with periodontitis showed marked bone loss and increased neutrophil infiltration in comparison with WTK rats. SHRs with periodontitis showed increased levels of TNF‐α and CXCL2, and a slight tendency for increased levels of CXCL5, in the gingival tissue but no increase in the level of CCL20. In SHRs, even without periodontitis, the levels of TNF‐α, CXCL2, CXCL5 and CCL20 showed a slight tendency to increase. In the WTK rats, TNF‐α, CXCL2 and CXCL5 levels were increased with periodontitis, but the level of CCL20 was not. iNOS was expressed in the gingival tissue of WTK rats and SHRs with periodontitis; however, SHRs appeared to express a higher level of iNOS than did WKT rats. The CRP level was elevated in both types of rats with periodontitis; however, the CRP level was higher in SHRs with periodontitis than in WTK rats with periodontitis.

Conclusion:  In SHRs, the hypertensive condition per se seems to favor the inflammatory processes that become potentiated with periodontitis, when compared with WKT rats.
Melatonin prevents ultraviolet radiation‐induced alterations in plasma membrane potential and intracellular pH in human keratinocytes
Authors: Kleszczyński Konrad , Tukaj Stefan , Kruse Nathalie , Zillikens Detlef , Fischer Tobias W.
Published: June 2012

Melatonin exhibits protective effects against ultraviolet radiation (UVR) via modulation of proinflammatory mediators and its free radical scavenging capacity. To date, several reports presented protective mechanisms of this agent against UVR‐induced alterations in mitochondria and nuclei. This investigation evaluates the potent preventing action of melatonin regarding early‐stage UVR‐mediated perturbations in plasma membrane potential (mbΔψ) and intracellular (cytosolic) pH (pH
i) analyzed by flow cytometry. Experiments were carried out in a dose‐ and time‐dependent manner using human keratinocytes [HaCaT and normal human epidermal keratinocytes (NHEK)]. First investigations, which used viability/cytotoxicity assays, showed the gradual mortality with increasing UVR doses and cultivation time. Pre‐incubation with melatonin (10−3 m) prior to UVR exposure reduced lactate dehydrogenase release by 30% (HaCaT) and 28% (NHEK) at the dose of 50 mJ/cm2 after 48 hr (P < 0.001). Furthermore, UVR caused hyperpolarization of mbΔψ immediately (0 hr) after irradiation (25 or 50 mJ/cm2). At the dose of 50 mJ/cm2, cells cultivated for 48 hr manifested a marked increase in mbΔψ by 112% (HaCaT) and 123% (NHEK). The presence of melatonin significantly protected the cells by 12% (HaCaT) and 14% (NHEK) (P < 0.001). Simultaneously, 50 mJ/cm2 induced dramatic acidification reaching after 24 hr the level of 6.40 (without melatonin), 6.56 (with melatonin) for HaCaT and 6.11 (without melatonin), 6.43 (with melatonin) for NHEK. The results presented provide information about the protective mechanisms of melatonin itself on one hand and, combined with data reported so far, confirm the potent antiapoptotic action of melatonin.
Correlation between cuspal inclination and tooth cracked syndrome: a three‐dimensional reconstruction measurement and finite element analysis
Authors: Qian Yunzhu , Zhou Xuefeng , Yang Jianxin
Published: June 2012

Background/Aim

This paper explored the correlation between cuspal inclination and tooth cracked syndrome by measuring and reconstructing the cuspal inclinations of cracked maxillary first molars through three‐dimensional (3D) finite element analysis (FEA).

Material and methods

The cuspal inclinations of 11 maxillary left first molars with cracked tooth syndrome and 22 intact controls were measured by 3D reconstruction. The mean values of each group were used to construct two 3D finite element models of maxillary first molar for comparing stress distribution under the loads of 200N at 0°, 45°, and 90°, respectively, to the tooth axis.

Results

There was statistically significant difference in the cuspal inclination between the incompletely fractured group and the intact control group (
P
 < 0.001), which was 5.5–6.7 degrees steeper. The model from the mean cuspal inclinations of the incompletely fractured molars showed the maximum tensile stress of 5.83, 10.87, and 25.32 MPa, respectively, in comparison with 5.40, 8.49, and 22.76 MPa for the model of the control group. Besides, the tensile stress was mainly at the center groove and cervical region of the molar model.

Conclusions

Steeper cuspal inclinations resulted in an increment in tensile stress that was mainly at the center groove and cervical region of the molar model under equivalent loads. Higher unfavorable tensile stress was generated with the increasing horizontal component load on the cuspal incline. This indicates an effective reduction of cuspal inclination to the compromised teeth for dentists.
Deletion of the Drosophila neuronal gene found in neurons disrupts brain anatomy and male courtship
Authors: Zanini D. , Jallon J‐M. , Rabinow L. , Samson M‐L
Published: June 2012

The fne (found‐in‐neurons) locus encodes one of the three paralogs of the ELAV gene family of Drosophila melanogaster. Members of this family are found throughout metazoans and encode RNA‐binding proteins with primarily neuronal localization, but with remarkably diverse functions given their high level of amino acid sequence conservation. The first identified member of the family, elav of Drosophila is a vital gene. Mutations in the second Drosophila elav paralog, rbp9, are viable but female sterile. No alleles of fne were previously available. FNE protein is normally present in the cytoplasm of all neurons throughout development. Here we describe the generation and characterization of fnenull mutations by homologous recombination. In contrast to elav and similar to rbp9, fnenull mutants are viable, but exhibit a specific and fully penetrant fusion of the β‐lobes in their mushroom bodies (MB), a paired neuropil of the central brain involved in a variety of complex behaviors. Mutant males have reduced courtship indices, but normal short‐ and long‐term courtship memory. Our data show that fne has specific functions which are non‐overlapping with the other two family members, namely in courtship behavior and in the development of the adult MB. The data further show that courtship memory does not require intact β‐lobes in the MB.
The protective roles of phosphorylated heat shock protein 27 in human cells harboring myoclonus epilepsy with ragged‐red fibers A8344G mtDNA mutation
Authors: Chen Hsueh‐Fu , Chen Chin‐Yi , Lin Ting‐Hui , Huang Zhao‐Wei , Chi Tang‐Hao , Ma Yi‐Shing , Wu Shi‐Bei , Wei Yau‐Huei , Hsieh Mingli
Published: June 2012

Mitochondrial DNA (mtDNA) mutations are associated with a large number of neuromuscular diseases. Myoclonus epilepsy with ragged‐red fibers (MERRF) syndrome is a mitochondrial disease inherited through the maternal lineage. The most common mutation in MERRF syndrome, the A8344G mutation of mtDNA, is associated with severe defects in mitochondrial protein synthesis, which impair the assembly and function of the respiratory chain. We have previously shown that there is a decreased level of heat shock protein 27 (HSP27) in lymphoblastoid cells derived from a MERRF patient and in cytoplasmic hybrids (cybrids) harboring the A8344G mutation of mtDNA. In the present study, we found a dramatic decrease in the level of phosphorylated HSP27 (p‐HSP27) in the mutant cybrids. Even though the steady‐state level of p‐HSP27 was reduced in the mutant cybrids, normal phosphorylation and dephosphorylation were observed upon exposure to stress, indicating normal kinase and phosphatase activities. To explore the roles that p‐HSP27 may play, transfection experiments with HSP27 mutants, in which three specific serines were replaced with alanine or aspartic acid, showed that the phosphomimicking HSP27 desensitized mutant cybrids to apoptotic stress induced by staurosporine (STS). After heat shock stress, p‐HSP27 was found to enter the nucleus immediately, and with a prolonged interval of recovery, p‐HSP27 returned to the cytoplasm in wild‐type cybrids but not in mutant cybrids. The translocation of p‐HSP27 was correlated with cell viability, as shown by the increased number of apoptotic cells after p‐HSP27 returned to the cytoplasm. In summary, our results demonstrate that p‐HSP27 provides significant protection when cells are exposed to different stresses in the cell model of MERRF syndrome. Therapeutic agents targeting anomalous HSP27 phosphorylation might represent a potential treatment for mitochondrial diseases.
Risk factors for 90‐day and 180‐day mortality in hospitalised patients with pressure ulcers
Authors: Flattau Anna , Blank Arthur E
Published: June 2012

An understanding of risk factors associated with mortality among pressure ulcer patients can inform prognostic counselling and treatment plans. This retrospective cohort study examined associations of comorbid illness, demographic characteristics and laboratory values with 90‐day and 90‐ to 180‐day mortality in adult hospitalised patients with pressure ulcers. Data were extracted from hospital databases at two academic urban hospitals. Covariates included mortality risk factors identified in other populations, including demographic and laboratory variables, DRG weight, ‘systemic infection or fever’ and comorbidity categories from the Charlson comorbidity index. In adjusted Cox proportional hazards models, diabetes, chronic renal failure, congestive heart failure and metastatic cancer were significantly associated with mortality in both time frames. There was no significant effect on mortality from dementia, hemiplegia/paraplegia, rheumatic disease, chronic pulmonary disease or peripheral vascular disease. Myocardial infarction, cerebrovascular disease, liver disease and human immunodeficiency virus/AIDS were associated with mortality in the 90‐day time frame only. ‘Systemic infection or fever’ was associated with mortality in the 90‐day time frame but did not show a confounding effect on other variables, and the only significant interaction term was with metastatic cancer. Albumin was the only studied laboratory value that was strongly associated with mortality. Understanding the context of comorbid illness in pressure ulcer patients sets the groundwork for more robust studies of patient‐ and population‐level outcomes, as well as study of heterogeneity within this group.
EFFECTS OF BLENDING OF WHEAT FLOUR WITH BARLEY FLOUR ON DOUGH AND STEAMED BREAD PROPERTIES
Authors: LIN SU‐YI , CHEN HUA‐HAN , LU SHIN , WANG PIN‐CHIH
Published: June 2012

Steamed bread is a fermented wheat flour product that is cooked by being steamed in a steamer. The properties of dough and the quality of steamed bread incorporated with barley flour at 10, 20 and 30% substitution levels are investigated. Increasing levels of barley flour correspondingly decreases the gluten content and increases the β‐glucan content. Upon incorporation of barley flour, the dough development time, departure time and stability time are decreased, but the mixing tolerance index is increased. The incorporation of barley flour into wheat flour also significantly decreases the extensibility, increases the value of R/E ratio and decreases the value of work input. In addition, increased levels of barley flour cause significant decreases in the specific volume, brightness and whiteness index of steamed bread, as well as increases in hardness and chewiness. This study also shows that six‐row barley pearl flour contains more dietary fiber and has a more favorable influence than barley endosperm flour.

PRACTICAL APPLICATIONS

This research illustrated the effect of barley on the mechanical properties of wheat flour dough, which was important for determining both the properties of the dough during processing and the quality of the end‐product.
A STUDY TO CHARACTERIZE THE MECHANICAL BEHAVIOR OF SEMISOLID VISCOELASTIC SYSTEMS UNDER COMPRESSION CHEWING – CASE STUDY OF AGAR GEL
Authors: YU JINGHU , SANTOS P.H.S. , CAMPANELLA O.H.
Published: June 2012

The present article establishes and validates a rheological model that can be used to characterize viscoelastic properties of food gels during compression under small and large deformations. Transient creep and standard compression tests were performed to characterize agar gels of different concentrations under small and large deformations in a texture analyzer. The Burgers model and a modified generalized linear viscoelastic (GLVE) model were used to describe the behavior of the gels in the linear and nonlinear viscoelastic region, respectively. However, the modified GLVE model seems not to capture the stress hardening behavior of agar gels during compression. The Ogden model was then used and successfully described the stress–strain behavior of agar gels at different strain rates.

PRACTICAL APPLICATIONS

Understanding the behavior of viscoelastic materials during large stresses and deformation is useful in the design of novel instruments that can mimic the mastication action to assess the texture of gel‐like foods as well as other food materials.
A synopsis of the genus Pyrus (Rosaceae) in Iran
Authors: Zamani Asghar , Attar Farideh , Maroofi Hosein
Published: June 2012

In this paper, a synopsis of the genus Pyrus L. in Iran is presented. A complete morphological identification key consisting of previously introduced species plus new species and newly recorded taxa is provided as well as a morphological description of each taxon. Moreover, the distribution of each species is mapped based on field observations, collected material and previously published records. Notes on chorology, phenology, taxonomical relationships, habitat, economical uses and a selection of examined specimens is provided. Most species are illustrated in fruit. Four newly recorded taxa, viz. P. spinosa, P. zangezura, P. × takhtadzhianii and P. × medvedevii are reported for the first time from Iran.
Some Empirical Evidence on Offender Time Discount Rates
Authors: Torre Andrew , Wraith Darren
Published: June 2012

The conventional wisdom is that offenders have very high discount rates not only with respect to income and fines but also with respect to time incarcerated. These rates are difficult to measure objectively and the usual approach is to ask subjects hypothetical questions and infer time preference from their answers. In this article, we propose estimating rates at which offenders discount time incarcerated by specifying their equilibrium plea, defined as the discount rate, which equates the time and expected time spent in jail following a guilty plea and a trial. Offenders are assumed to exhibit positive time preference and discount time spent in jail at a constant rate. Our choice of sample is interesting because the offenders are not on bail, punishment is not delayed and the offences are planned therefore conforming to Becker’s model of the decision to commit a crime. Contrary to the discussion in the literature, we do not find evidence of consistently high time discount rates, and therefore cannot unequivocally infer that the prison experience always results in low levels of specific deterrence.
The Re‐engagement in Education of Early School Leavers*
Authors: Black David , Polidano Cain , Tseng Yi‐Ping
Published: June 2012

By OECD standards, the share of the Australian labour force with at least a secondary school qualification is low. One way to rectify this shortfall is to improve rates of re‐engagement in education among early school leavers. This paper examines the patterns of re‐engagement among early school leavers in the Household, Income and Labour Dynamics in Australia sample. A key finding is that the early years after leaving school are crucially important, with rates of re‐engagement dropping dramatically in the first three years out from school. For young adults up to age twenty four, results suggest that finding work, especially satisfying work, is an important motivator for returning to study. For older adults, re‐engaging is linked to retraining after commencing a new job and returning to study after having kids.
The Dynamics of Environmental Giving in Canada: Evidence of Rising Demand for Environmental Quality?
Authors: Hossain Belayet , Lamb Laura
Published: June 2012

This study explores environmental giving behaviour over time in Canada and considers whether changes in such behaviour serve as an indication of evolving preferences for environmental quality. The data sets of the 1997 National Survey of Giving, Volunteering and Participating (NSGVP) and the 2007 Canada Survey of Giving, Volunteering and Participating (CSGVP) are analysed using the probit selection and Heckman selection models to study environmental giving behaviour. The results suggest that the demand for environmental quality in Canada may have increased over time and that several economic, socio‐demographic and geographic factors influence the likelihood of donating and the amount of the donation expenditure. The findings have implications for public policy.
Status of Research on Environmentally Assisted Cracking in LWR Pressure Vessel Steels
Authors: Ford F. P.
Published: June 2012

This paper reviews collaborative work that has the objective of defining, from first principles, the environmentally assisted crack growth rates in the Type A533B or A508 low-alloy steel/water system at 288°C under static and cyclic loading conditions. These theoretical rates are then used to assess the validity of the current ASME XI life evaluation code. The investigations, which were conducted by members of the International Cyclic Crack Growth Rate Group, have centered around (a) defining a working hypothesis for environmentally assisted cracking, (b) determining the nature and magnitude of crack tip environments and reaction rates that are pertinent to the crack advance hypotheses, (c) quantitatively validating a hypothesis by comparing observed and theoretical values, and (d) using the qualified mechanism to evalute the validity of current life-evaluation codes for environmentally assisted crack propagation. It is concluded that, on the basis of the bulk of present data, the slip dissolution (film rupture) model seems to be quantitatively the most valid crack advance mechanism for this system at 288°C. However, under certain system conditions, it is possible that an additional advance component due to environmentally assisted cleavage may become significant. Regardless of these nuances, however, it is apparent that the current ASME XI code is probably conservative for extended cyclic loading conditions, and that a time-based (rather than a cyclic-base) code would give a more realistic assessment of the structural integrity for the expected range of load/time histories in pressure vessels.
Disruptive Failure of Pressure Vessels: Preliminary Design Guidelines for Fragment Velocity and the Extent of the Hazard Zone
Authors: Baum M. R.
Published: June 2012

In the event of an accident, an industrial plant must be capable of being shut down in a safe, controlled manner. Thus, when a plant containing high-pressure fluids is being designed, the potential damage to essential shut-down equipment resulting from rupture of the pressure envelope must be assessed and, where necessary, protection provided. For example, pressure vessel rupture may generate missiles; i.e., sections of the pressure envelope become detached and are accelerated to significant velocities by the expanding fluid contents. An assessment of the consequences of pressure vessel rupture must therefore include estimates of the likely extent of the missile impact zone and the potential damage to equipment within that zone, which are both functions of the missile velocity. This paper describes preliminary guidelines for defining the velocity of the various types of missile which can be generated by pressure vessel failure. The recommended velocities are based on experimental evidence, including a large body of previously unpublished BNL (Berkeley Nuclear Laboratories) data. The extent of the hazard zone is also considered.
Allowable Stresses for Nonrectangular Sections Under Combined Axial and Bending Loads
Authors: Chattopadhyay S.
Published: June 2012

The design stress allowables for various loading conditions involving bending in Section III, Division 1 and Section VIII, Division 2 of the ASME Boiler and Pressure Vessel Code are based on the assumption of a rectangular cross section of the structural members. These allowables do not necessarily provide the same level of safety for all general cross sections. In this work, stress allowables have been proposed for design, level C and test condition loadings to provide adequate safety for all combinations of axial and bending loads. The limits are based on an in-depth study of the interaction curves for the fully plastic condition under combined axial and bending loads. These proposed limits are intended to replace the existing ones in the ASME Code. These modifications apply to the design, level C and testing limits. (NB-3221.3, NB-3224 and NB-3226) of Section III, Division 1, and to the Design and Testing limits (AD-140 and AD-151) of Section VIII, Division 2 of the ASME Code. The modified limits are based on the inclusion of shape factors of individual cross sections.
Bilaterian Burrows and Grazing Behavior at >585 Million Years Ago
Authors: Pecoits Ernesto , Konhauser Kurt O. , Aubet Natalie R. , Heaman Larry M. , Veroslavsky Gerardo , Stern Richard A. , Gingras Murray K.
Published: June 2012

Early Burrowers

Direct fossil evidence of animals from Ediacaran period—the time in Earth's history just before extensive animal diversification in the Cambrian—is scant. However, the remains of animal activity in sediment, which remain intact through geologic time can provide clues about animal behavior and evolution.

Pecoits
et al.

(p.
1693
; see the Perspective by

Droser and Gehling

) found a suite of fossil animal burrows in sedimentary rocks in Uruguay. Radiometric dating places the age of the structures at ∼585 million years old, coinciding with the likely emergence of stem-group bilaterians. The complex morphologies of the fossil burrows suggest that these animals actively grazed and had the ability to burrow deep within sediments.
Elastic Coupling Between RNA Degradation and Unwinding by an Exoribonuclease
Authors: Lee Gwangrog , Bratkowski Matthew A. , Ding Fang , Ke Ailong , Ha Taekjip
Published: June 2012

Loading a Spring

To regulate cellular RNA levels, transcription must be balanced by RNA degradation. An important player is the exosome, which can unwind and degrade structured RNA.

Lee
et al.

(p.
1726
) used single-molecule fluorescence analysis to investigate how degradation and unwinding are coupled in the catalytic subunit of the yeast exosome complex, Rrp44. Rrp44 apparently digests several base pairs without unwinding, accumulates the energy, which it then uses to unwind four to five base pairs in a burst. Similar spring-like behavior has been proposed for conventional helicases, except that the stored energy comes from hydrolysis of adenosine triphosphate rather than the RNA polymer.
European Teacher Training Reforms
Authors: Bauer Johannes , Prenzel Manfred
Published: June 2012

The Bologna Process has contributed to a more academic and research-based orientation in European teacher education.
Elemental Profiles Reflect Plant Adaptations to the Environment
Authors: Baxter Ivan , Dilkes Brian P.
Published: June 2012

Most mineral elements found in plant tissues come exclusively from the soil, necessitating that plants adapt to highly variable soil compositions to survive and thrive. Profiling element concentrations in genetically diverse plant populations is providing insights into the plant-environment interactions that control elemental accumulation, as well as identifying the underlying genes. The resulting molecular understanding of plant adaptation to the environment both demonstrates how soils can shape genetic diversity and provides solutions to important agricultural challenges.
No Body Is As It Seems
The Weighty Body
Fat or Thin, Vanity or Insanity Museum Boerhaave, Leiden, Netherlands. 13 April to 9 September 2012. www.museumboerhaave.nl
The Weighty Body
Fat or Thin, Vanity or Insanity

Museum Dr. Guislain and Museum Boerhaave

Lannoo, Tielt, Belgium, 2010. Paper, 194 pp. £27.50, €29.95. ISBN 9789020992151.
Authors: Whiteley Louise
Published: June 2012

This exhibition at Museum Boerhaave (Leiden) offers thought-provoking perspectives on eating disorders and obesity.
Norman L. Letvin (1949–2012)
Authors: Nabel Gary J. , Wolinsky Steven M. , Haynes Barton F.
Published: June 2012

A world leader in HIV/AIDS research was a dedicated mentor, influential international adviser, and a remarkable musician.
Rise and fall of shigella antibiotic resistance
Authors: Meyer P W , Lerman S J
Published: June 2012

Ampicillin resistance of shigellae first appeared in Omaha in 1971, peaked at 68% between 1973 and 1974, and declined to 7% between 1977 and 1978. This reflected the rise and fall of strains with nine different multiple antibiotic resistance patterns that included ampicillin.
Nuclear magnetic resonance spectrometric assay of beta-lactamase
Authors: Kono M , O'Hara K , Shiomi Y
Published: June 2012

Beta-Lactam antibiotics and the crude enzyme were mixed in deuterium oxide and placed in a nuclear magnetic resonance tube. The change of the nuclear magnetic resonance spectrum during the enzymatic reaction was then analyzed to determine beta-lactamase activity. By using beta-lactam antibiotics such as penicillins, cephalosporins, and cephamycins as substrates, a comparison of the beta-lactamase activities was made between the nuclear magnetic resonance spectrometric assay and the iodometric assay. There was a close correlation between these two methods.
Susceptibility of zoopathogenic fungi to phytoalexins
Authors: Gordon M A , Lapa E W , Fitter M S , Lindsay M
Published: June 2012

Phytoalexins are a group of low-molecular-weight antibiotics produced by higher plants in response to infection by relatively avirulent microorganisms. They are of relatively low toxicity for mammalian cells and have been reported to possess a broad spectrum of antimicrobial activity against bacteria and phytopathogenic fungi. Employing a broth dilution technique, we have found the zoopathogens Petriellidium boydii, Aspergillus flavus, A. fumigatus, Candida albicans, Coccidioides immitis, Cryptococcus neoformans, Histoplasma capsulatum, Rhizopus oryzae, Sporothrix schenckii, and Trichophyton rubrum to be inhibited by one or more of the phytoalexins maackiain, medicarpin, phaseollin, phaseollin isoflavan, pisatin, sativan, and vestitol in concentrations of from 12.5 to 50 microgram/ml. Phaseollin isofalvan was the most effective of these. In agar cup diffusion tests growth of the yeast form of Blastomyces dermatitidis was inhibited by phaseollin at 50 microgram/ml and by phaseollin isoflavan at 25 microgram/ml. Susceptibility of the mycelial form of B. dermatitidis to these two compounds was demonstrated by inhibition of radial extension on agar plates.
In vitro antibacterial activity and susceptibility of cefsulodin, an antipseudomonal cephalosporin, to beta-lactamases
Authors: King A , Shannon K , Phillips I
Published: June 2012

Cefsulodin sodium (SCE-129, CGP-7174/E), active in minimum inhibitory concentrations (MICs) of 0.5 to 64 microgram/ml, was about 16- to 32-fold more active than carbenicillin against Psuedomonas aeruginosa. It was also active against P. diminuta, P. maltophilia, P. paucimobilis, and P. pseudoalcaligenes (MICs of 1 to 32 microgram/ml) but not against other species of Pseudomonas or other gram-negative bacteria. Except with highly carbenicillin-resistant isolates, MICs of cefsulodin for P. aeruginosa were little affected by an increase in the inoculum. With a small inoculum, minimum bactericidal concentrations (MBCs) were the same as or twice the MIC, but increasing the inoculum had a greater effect on the MBC than on the MIC. Cefsulodin was not hydrolyzed by the beta-lactamase induced in P. aeruginosa by growth in the presence of benzylpenicillin and was a poor substrate for beta-lactamases from Enterobacter cloacae and Proteus morganii. However, it was hydrolyzed, albeit slowly, by the beta-lactamase produced by most of our highly carbenicillin-resistant isolates of P. aeruginosa and by TEM-type beta-lactamases.
Absorption and disposition kinetics of amoxicillin in normal human subjects
Authors: Arancibia A , Guttmann J , González G , González C
Published: June 2012

Pharmacokinetic parameters of amoxicillin were studied in healthy fasted subjects afqer both oral and intravenous administration of a single 500-mg dose. Serum levels and urinary excretion rates were determined at various time intervals by a microbiological method. The conventional two-compartment model with elimination occurring from the central compartment was used to analyze the data. Mean values were 3.40 h-1 for alpha and 0.68 h-1 for beta. Distribution constants kappa 12 and kappa 21 were 0.92 h-1 and 1.99 h-1, respectively. The rate constant for elimination from the central compartment, kappa 10, was 1.16 h-1. The volume of distribution was 20.2 liters (0.30 liter/kg), and the serum clearance was 13.3 liters/h. The absorption rate constant, kappa a, in the oral study, calculated by the Loo-Riegelman method, was 1.02 h-1, and the absorption half-life was 0.72 h. Absolute bioavailability after the oral dose was determined by comparing both the areas under the curve (AUC) and fractions of the antibiotic excreted unchanged in the urine. The AUC after oral administration was 77.4% of the intravenous AUC. On the other hand, recovery from the urine was 43.4% after the oral dose and 57.4% after the intravenous dose, indicating 76.5% bioavailability.
Parameters controlling interbacterial plasmid spreading in a gnotoxenic chicken gut system: influence of plasmid and bacterial mutations
Authors: Sansonetti P , Lafont J P , Jaffé-Brachet A , Guillot J F , Chaslus-Dancla E
Published: June 2012

Conjugative transfer of R plasmids R64 and R64drd-11 has been compared in vitro and in vivo without selective pressure by antibiotics in a simplified experimental system; the ecosystem was the bowel of germfree chickens, with the host bacteria almost isogenic, and the plasmids differing only in their conjugative transfer frequency. The spread of repressed and derepressed (drd) R plasmids in recipient bacterial populations was very extensive. The repressed phenotype had only a transient effect during the first 4 h. The level of implantation of the donor bacterial population seems to be of minor importance. Only with a poor recipient (con strain) could the spread of R plasmids be reduced and a steady state with a predominantly sensitive bacterial population be established. It is suggested that this steady state results from an equilibrium between the frequencies of R plasmid transfer and loss.
Bacteriostatic and bactericidal activities of beta-lactam antibiotics enhanced by the addition of low concentrations of gentamicin
Authors: Masuda G , Nakamura K , Yajima T , Saku K
Published: June 2012

The combined effects of low concentrations of gentamicin on certain beta-lactam antibiotics were studied by the agar plate method. the combination of gentamicin with cephalothin produced synergism against 17 of 26 strains of Escherichia coli and 19 of 27 strains of Klebsiella sp. if assessed at the bacteriostatic (minimal inhibitory concentration) level. Synergy against many more strains was apparent when bactericidal concentrations were used. Synergy against most of these strains was observed if bactericidal concentrations with brief exposure times (3 h) to the antibiotics were used for measurement. Additive effects were observed in almost all of the remaining strains. The combination of gentamicin and carbenicillin were synergistic against most strains of Pseudomonas aeruginosa when any bacteriostatic or bactericidal measurement was used as the criterion.
Multiple changes of penicillin-binding proteins in penicillin-resistant clinical isolates of Streptococcus pneumoniae
Authors: Hakenbeck R , Tarpay M , Tomasz A
Published: June 2012

Penicillin-binding properties and characteristics of penicillin-binding proteins (PBPs) were investigated in several clinical isolates of Streptococcus pneumoniae differing in their susceptibilities to penicillin (minimal inhibitory concentration [MIC], 0.03 to 0.5 microgram/ml) and compared with the penicillin-susceptible strain R36A (MIC, 0.07 microgram/ml). Several changes accompanied the development of resistance: the relative affinity to penicillin of whole cells, isolated membranes, and two major PBPs after in vivo or in vitro labeling decreased (with increasing resistance). Furthermore, one additional PBP (2') appeared in four of five relatively resistant strains with an MIC of 0.25 microgram/ml and higher. PBP 3 maintained the same high affinity toward penicillin in all strains under all labeling conditions.
Intrarenal distribution of trimethoprim and sulfamethoxazole
Authors: Trottier S , Bergeron M G , Lessard C
Published: June 2012

In the present study, rats were given trimethoprim (TMP, 10 mg/kg), sulfamethoxazole (SMZ, 50 mg/kg), or a combination of the respective doses of TMP and SMZ. Thirty-six rats received each of the drugs studied. Six recipients of a compound (or mixture) were evaluated hourly, from 1 to 6 h after intraperitoneal injection of the agent. At each timed interval, serum, urine, cortex, medulla, and papilla were analyzed for drug content. Peak serum values of 1.1 microgram of TMP and 131.1 microgram of active SMZ (nonacetylated sulfonamide) per ml were observed after injection of the combination TMP-SMZ. Although the cortical, medullary, and papillary TMP concentrations were severalfold higher than the respective serum values (P < 0.01), microbiologically active SMZ did not concentrate in the renal parenchyma and was found in lower concentration there than in the serum (P < 0.01). The levels of SMZ in all parts of the kidney of animals which received the mixture SMZ-TMP were lower than those detected in the animals which were given SMZ alone. The average ratio of active SMZ to TMP within the medulla and the papilla was less than 20 to 1 in the first 2 h. The intrarenal distribution of these drugs may have therapeutic implications.
Effect of contamination levels on antimicrobial susceptibilities tested by Autobac I
Authors: Shahidi A , Choey I
Published: June 2012

Two gram-positive and five gram-negative species of bacteria commonly isolated from clinical specimens were used in 704 different inoculum ratios against 11 antimicrobial agents to study the effect of contamination levels on the susceptibility patterns of mixed cultures. Staphylococcus aureus, Streptococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis, and Enterobacter cloacae were used in 12 combinations of two each. The pure culture inoculum tubes were prepared according to Autobac I (Pfizer Inc.) instructions. Various amounts from 0.01 to 2.0 ml of one bacterial inoculum were mixed with various amounts of the other bacterial inoculum to form 16 mixtures to low-thymidine eugonic broth. In the majority of cases, susceptibility to antimicrobial agents started to change at 12.5% contamination level. Of 1,936 mixtures with 5% contamination levels, 98.5 to 99.2% exhibited the same susceptibilities as did the pure cultures. These results suggest that generally contamination levels of more than 5% or 70,000 to 150,000 bacteria per ml, are responsible for a significant change in apparent drug susceptibility.
Dissemination of an antibiotic resistance plasmid in hospital patient flora
Authors: O'Brien T F , Ross D G , Guzman M A , Medeiros A A , Hedges R W , Botstein D
Published: June 2012

The 2'' aminoglycoside nucleotidyltransferase, AAD (2''), which adenylates gentamicin, tobramycin, and kanamycin, became prevalent over several months in multiple strains and species of Enterobacteriaceae isolated at one hospital. Eight plasmids with the gene for this enzyme purified from different strains and species isolated at different times had similar EcoRI digestion fragments, indicating that the gene had disseminated on one plasmid without transposition. This 56.5-megadalton plasmid of incompatibility group M, which also carried three other resistance genes, spread, at first, largely in one strain of Klebsiella pneumoniae, which later disappeared. It transferred to some strains which tended not to colonize other patients and later circulated predominantly in Serratia marcescens. Computer surveillance of routine hospital laboratory results was able to detect and trace the gene and the plasmid and measure their effect on resistance prevalence.
Antibacterial activity of ceftizoxime, a beta-lactamase-stable cephalosporin
Authors: Fu K P , Neu H C
Published: June 2012

The in vitro activity of ceftizoxime was compared with that of other beta-lactam antibiotics against 538 isolates. Ceftizoxime was the most active agent tested against Escherichia coli and Klebsiella, inhibiting 80% at 0.025 microgram/ml. It was more active than cefotaxime against Enterobacter cloacae and E. aerogenes. Ceftizoxime was more active than cefoxitin, cefotaxime, cefoperazone, and carbenicillin against Proteus mirabilis and indole-positive Proteus. It inhibited 97% of multiresistant Serratia isolates at 12.5 microgram/ml, whereas cefotaxime inhibited only 19%. Ceftizoxime was less active than cefotaxime and cefoperazone against Pseudomonas aeruginosa, but was more active than carbenicillin. It was more active than cefotaxime and cefoxitin against Bacteroides. It was not appreciably destroyed by beta-lactamases of Staphylococcus aureus, Enterobacteriaceae, or Pseudomonas.
Cefoxitin concentrations in the cerebrospinal fluids of patients with meningitis
Authors: Humbert G , Leroy A , Rogez J P , Cherubin C
Published: June 2012

The concentrations of cefoxitin in serum and cerebrospinal fluid (CSF) were measured simultaneously in three groups of patients, 12 with aseptic meningitis (group 1) and 17 and 14 with bacterial meningitis (groups 2 and 3). The patients in group 1 received a single intravenous dose of 2 g of cefoxitin without other antimicrobial therapy. In addition to conventional doses of ampicillin or benzyl penicillin, patients in groups 2 and 3 received repeated infusions of 2 g of cefoxitin every 4 h for the first 3 or 4 days of the study and again on day 10. Additionally, group 3 received probenecid in a loading dose of 1 g followed by 0.5 g every 6 or 8 h. Concentrations of cefoxitin in CSF and serum were determined 1 or 2 h after infusion in group 2 and 2 h after infusion in group 3. The concentrations of cefoxitin in CSF did not reach detectable levels (1.56 microgram/ml) in 11 of the 12 patients in group 1. A level of 2.8 microgram of cefoxitin per ml of CSF was found, with an accompanying level of 30 microgram/ml of serum, in patient 12. In the group 2 patients with bacterial meningitis, the mean CSF concentrations were 3.3, 4.7, and 2.9 microgram/ ml on days 1, 3, and 10 of treatment, with simultaneous serum levels of 8, 9, and 8 microgram/ml. At similar times periods, the mean levels of cefoxitin in group 3 patients (with concomitant probenecid) were 8.6, 12.3, and 4.3 microgram/ml of CSF and 57, 35, 27 microgram/ml of serum.
In vitro susceptibility of Pseudomonas aeruginosa to carbenicillin, glycine, and ethylenediaminetetraacetic acid combinations
Authors: Gerberick G F , Castric P A
Published: June 2012

Striking bacterial activity against Pseudomonas aeruginosa 9D-2 was achieved by glycine-carbenicillin, ethylenediaminetetraacetic acid-carbenicillin, and glycine-ethylenediaminetetraacetic acid combinations, whereas none of the agents used alone was capable of the same degree of bactericidal activity. Studies using a microtiter modification of the checkerboard technique were performed to evaluate the comparative activity of these antimicrobial combinations. Isobolograms showed synergistic effects with carbenicillin-glycine, carbenicillin-ethylene-diaminetetraacetic acid, and glycine-ethylenediaminetetraacetic acid combinations. Bacterial growth inhibitory curves with subinhibitory concentrations of these agents in combination confirmed these findings.
Practical anaerobic broth-disk elution susceptibility test
Authors: Jorgensen J H , Alexander G A , Johnson J E
Published: June 2012

A modified broth-disk elution method for routine susceptibility testing of anaerobic bacteria was compared with the proposed reference agar dilution method under study by the National Committee on Clinical Laboratory Standards. The broth-disk elution method used a 24-h test incubation period, Schaedler broth medium supplemented with menadione, and GasPak (BBL Microbiology Systems) incubation. Results obtained by this method compared favorably with carbenicillin, chloramphenicol, clindamycin, and penicillin minimal inhibitory concentrations. The 24-h incubation period led to major discrepancies with tetracycline disk elution tests. This method represents a practical routine procedure for testing of anaerobic bacterial isolates in hospital clinical microbiology laboratories.
Evaluation of an enzyme immunoassay for serum gentamicin
Authors: O'Leary T D , Ratcliff R M , Geary T D
Published: June 2012

The EMIT (Enzyme Multiplied Immunoassay Technique) for serum gentamicin determination was evaluated by a standard procedure. The precision, accuracy, and specificity were assessed and proved satisfactory. Comparison with a bioassay was done, and results for patient samples showed a correlation coefficient of 0.95 between the two methods. Advantages of the enzyme immunoassay system were the provision of results within 15 min of receipt of blood in the laboratory, a requirement of minimal technical expertise, and an applicability to both large and small workloads. The EMIT proved during evaluation to be a practical alternative to current bioassays for the determination of serum gentamicin concentrations.
5-epi-Sisomicin and 5-epi-Gentamicin B: substrates for aminoglycoside-modifying enzymes that retain activity against aminoglycoside-resistant bacteria
Authors: Vastola A P , Altschaefl J , Harford S
Published: June 2012

A number of bacterial strains, each possessing a different aminoglycoside-modifying enzyme, were examined for susceptibility to sisomicin and gentamicin B and the semisynthetic derivatives 5-epi-sisomicin and 5-epi-gentamicin B. Although strains possessing AAC (6') or APH(3') enzymes were equally resistant to the 5-epi-compounds, those possessing AAC(3)-I, ANT(2"), or AAC(2') enzymes were much more sensitive to the 5-epi derivatives. Analysis of partially purified aminoglycoside-modifying enzymes from the strains showed that the 5-epi compounds were substrates even for those enzymes found in susceptible strains [AAC(3)-I, ANT(2"), and AAC(2')]. However, a more detailed study of the enzymes showed that they had much increased Km values for the 5-epi derivatives; the 5-epi compounds were much less effectively modified than the parent antibiotics. This confirms and extends the notion that enzymatic modification of aminoglycosides is not in itself sufficient to confer resistance to the drugs, but also that the modification must be efficient, as reflected in the Km values.
New schedule for tobramycin administration
Authors: Lawson R D , Bodey G P , Pan T , Smith T L
Published: June 2012

Ten patients received a loading dose of tobramycin of 60 mg/m2 intravenously over 0.5 h followed immediately by 60 mg/m2 over 2 h every 4 h. The highest mean serum concentration (at the end of the loading dose) was 6.0 +/- 0.3 microgram/ml (range, 3.2 to 10.9 microgram/ml). The mean serum concentration 2 h after the end of the initial 2-h infusion was 3.0 +/- 0.2 microgram/ml (range, 1.6 to 3.9 microgram/ml). This schedule of tobramycin was used to treat 117 patients with presumed or proven infection. There were no differences in the mean serum concentrations of tobramycin at comparable times on days 3 to 4 and 6 to 7. Only 60% of patients had serum levels between 3 micrograms/ml (trough) and 10 micrograms/ml (peak). This intermittent schedule of administration resulted in substantial fluctuations in serum concentrations of tobramycin and produced trough concentrations which were too low or peak concentrations which were too high in some patients.
Rifampin and bacteriocin resistance in Bacteroides fragilis
Authors: Mossie K G , Jones D T , Robb F T , Woods D R
Published: June 2012

A low-molecular-weight bacteriocin produced by a Bacteroides fragilis strain inhibited ribonucleic acid polymerase activity in crude extracts of a susceptible B. fragilis indicator strain. A total of 10 rifampin-resistant mutants of the indicator strain were isolated. Nine of the rifampin-resistant mutants were resistant to the bacteriocin, and the other mutant was hypersusceptible. The rifampin- and bacteriocin-resistant mutants all adsorbed approximately the same amount of the bacteriocin as the indicator strain. Two of these rifampin- and bacteriocin-resistant mutants were investigated further, and the polymerase activity in crude extracts of the two mutants was not affected by either rifampin or the bacteriocin. The in vitro ribonucleic acid polymerase activity of the hypersusceptible strain was more susceptible to the bacteriocin than the parent indicator strain was. The bacteriocin-producing strain was susceptible to rifampin but was resistant to its own bacteriocin in vivo. The in vitro ribonucleic acid polymerase activity of the producer strain was only slightly affected by 64 arbitrary units of the bacteriocin. Increasing concentrations of the bacteriocin inhibited ribonucleic acid polymerase extracts of the producer strain.