bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of the Interaction Between β‐Carboline‐3‐carboxylic acid N‐Methylamide and Polynucleotides on Singlet Oxygen Quantum Yield and DNA Oxidative Damage
Authors: García‐Zubiri Iñigo X. , Burrows Hugh D. , Sérgio Seixas de Melo J. , Pina Joao , Monteserín María , Tapia María J. 
Published: November 2007

AbstractThe complexation of β‐carboline‐3‐carboxylic acid N‐methylamide (βCMAM) with the sodium salts of the nucleotides polyadenylic (Poly A), polycytidylic (Poly C), polyguanylic (Poly G), polythymidylic (Poly T) and polyuridylic (Poly U) acids, and with double stranded (dsDNA) and single stranded deoxyribonucleic acids (ssDNA) was studied at pH 4, 6 and 9. Predominant 1:1 complex formation is indicated from Job plots. Association constants were determined using the Benesi–Hildebrand equation. βCMAM‐sensitized singlet oxygen quantum yields were determined at pH 4, 6 and 9, and the effects on this of adding oligonucleotides, dsDNA and ssDNA were studied at the three pH values. With dsDNA, the effect on βCMAM triplet state formation was also determined through triplet–triplet transient absorption spectra. To evaluate possible oxidative damage of DNA following singlet oxygen βCMAM photosensitization, we used thiobarbituric acid‐reactivity assays and electrophoretic separation of DNA assays. The results showed no oxidative damage at the level of DNA degradation or strand break.
UV‐induced Degradation of Collagen I Is Mediated by Soluble Factors Released from Keratinocytes†
Authors: Yarosh Daniel , Dong Kelly , Smiles Kenneth 
Published: November 2007

AbstractPhotoaging is a complex condition but its hallmark is the destruction of dermal collagen. This has been attributed to the direct activation of fibroblast matrix metalloproteinases by solar UV. However, we report here that unirradiated fibroblasts increase metalloproteinase production and digest collagen when exposed to cell culture media from irradiated keratinocytes. Enhanced DNA repair in the keratinocytes ameliorates this response. This suggests that soluble factors induced by DNA damage in UV‐exposed epidermal keratinocytes signal collagen degradation by fibroblasts in the dermis. This motif of DNA damage in keratinocytes producing effects on other cell types mediated by soluble factors was first identified by Kripke and colleagues in studying UV‐induced immune suppression.
Accumulation and Interaction of Hypericin in Low‐density Lipoprotein— A Photophysical Study
Authors: Mukherjee Prasun , Adhikary Ramkrishna , Halder Mintu , Petrich Jacob W. , Miskovsky Pavol 
Published: November 2007

AbstractThe accumulation and interaction of hypericin with the biologically important macromolecule, low‐density lipoprotein (LDL), is investigated using various steady‐state and time‐resolved fluorescence measurements. It is concluded that multiple hypericins can penetrate considerably deeply into the LDL molecule. Up to ∼20 nonaggregated hypericin molecules can enter LDL; but upon increasing the hypericin concentration, the fluorescence lifetime of hypericin decreases drastically, suggesting most likely the self‐quenching of aggregated hypericin. There is also evidence of energy transfer from tryptophans of the constituent protein, apoB‐100, to hypericin in LDL. The results demonstrate the ability of LDL to solubilize hypericin (a known photosensitizer) in nonaggregated form, which has implications for the construction of drug delivery systems.
Ultraviolet‐A and ‐B Differentially Modify the Tyrosine‐Kinase Profile of Human Keratinocytes and Induce the Expression of Arg†
Authors: Klosner Gabriele , Varecka Roland , Knobler Robert , Trautinger Franz 
Published: November 2007

AbstractTo investigate the expression profile of protein tyrosine kinases (PTKs) in normal human epidermal keratinocytes (NHEK) in response to UVA and UVB we employed a reversed transcriptase polymerase chain reaction (PCR) approach using degenerate primers derived from the conserved catalytic domain of PTKs. Quantitative real‐time PCR with specific primers was used to confirm the influence of UV on the expression of the identified PTKs. Arg (Abelson‐related gene, Abl2) was the PTK with the highest prevalence (30% of all PTKs) and UVA led to a further induction of Arg expression reaching nine‐fold mRNA baseline expression at 17 h after irradiation. UVB was followed by an initial downregulation and a subsequent increase in Arg mRNA reaching five‐fold baseline levels after 24 h. We conclude that UVA and UVB differentially modify the expression of PTKs in NHEK, and that Arg appears to have a major role in the response of keratinocytes to UV. These results provide a basis for further studies of PTK in UV‐induced signaling that regulates protective responses, cell growth and carcinogenesis in the skin.
Spectrophotometric Methods for Quantifying Pigmentation in Human Hair—Influence of MC1R Genotype and Environment
Authors: Shekar Sri N. , Duffy David L. , Frudakis Tony , Montgomery Grant W. , James Michael R. , Sturm Richard A. , Martin Nicholas G. 
Published: November 2007

AbstractEumelanin (brown/black melanin) and pheomelanin (red/yellow melanin) in human hair can be quantified using chemical methods or approximated using spectrophotometric methods. Chemical methods consume greater resources, making them less attractive for epidemiological studies. This investigation sought to identify the spectrophotometric measures that best explain the light–dark continuum of hair color and the measure that is best able to distinguish red hair from nonred hair. Genetic analysis was performed on these two measures to determine the proportion of genetic and environmental influences on variation in these traits. Reflectance curves along the visible spectrum and subjective ratings of hair color were collected from 1730 adolescent twin individuals. Discriminant class analyses were performed to determine the spectrophotometric measure that could best proxy for eumelanin and pheomelanin quantities. The ratio of light reflected in the green portion of the spectrum to that reflected in the red portion of the spectrum was best able to distinguish red hair from nonred hair. Melanocortin 1 receptor (MC1R) genotype explained some, but not all, variation in this measure. Light absorbed in the red portion of the spectrum was best able to explain the light–dark continuum of hair color. Variance components analysis showed that there were qualitatively different genetic influences between males and females for the light–dark continuum of hair. Our results show that spectrophotometric measures approximating variation in eumelanin and pheomelanin may be considered as an alternative to chemical methods in larger epidemiological studies.
Chemistry of Mixed Melanogenesis—Pivotal Roles of Dopaquinone†
Authors: Ito Shosuke , Wakamatsu Kazumasa 
Published: November 2007

AbstractMelanins can be classified into two major groups—insoluble brown to black pigments termed eumelanin and alkali‐soluble yellow to reddish‐brown pigments termed pheomelanin. Both types of pigment derive from the common precursor dopaquinone (ortho‐quinone of 3,4‐dihydroxyphenylalanine) which is formedviathe oxidation ofl‐tyrosine by the melanogenic enzyme tyrosinase. Dopaquinone is a highly reactiveortho‐quinone that plays pivotal roles in thechemicalcontrol of melanogenesis. In the absence of sulfhydryl compounds, dopaquinone undergoes intramolecular cyclization to form cyclodopa, which is then rapidly oxidized by a redox reaction with dopaquinone to give dopachrome (and dopa). Dopachrome then gradually and spontaneously rearranges to form 5,6‐dihydroxyindole and to a lesser extent 5,6‐dihydroxyindole‐2‐carboxylic acid, the ratio of which is determined by a distinct melanogenic enzyme termed dopachrome tautomerase (tyrosinase‐related protein‐2). Oxidation and subsequent polymerization of these dihydroxyindoles leads to the production of eumelanin. However, when cysteine is present, this process gives rise preferentially to the production of cysteinyldopa isomers. Cysteinyldopas are subsequently oxidized through redox reaction with dopaquinone to form cysteinyldopaquinones that eventually lead to the production of pheomelanin. Pulse radiolysis studies of early stages of melanogenesis (involving dopaquinone and cysteine) indicate that mixed melanogenesis proceeds in three distinct stages—the initial production of cysteinyldopas, followed by their oxidation to produce pheomelanin, followed finally by the production of eumelanin. Based on these data, a casing model of mixed melanogenesis is proposed in which a preformed pheomelanic core is covered by a eumelanic surface.
Evidence of oxidative stress as a cofactor in the development of insulin resistance in patients with chronic hepatitis C
Authors: Mitsuyoshi Hironori , Itoh Yoshito , Sumida Yoshio , Minami Masahito , Yasui Kouichirou , Nakashima Toshiaki , Okanoue Takeshi 
Published: November 2007

Aim:  The mechanisms by which metabolic disorders develop in patients with chronic hepatitis C are unknown. Our study aimed to test whether oxidative stress contributes to these mechanisms.Methods:  The index of homeostasis model assessment–insulin resistance (HOMA–IR) and serum and hepatic levels of thioredoxin (Trx), which are markers of oxidative stress, were evaluated in 203 biopsy‐proven chronic hepatitis C patients with hepatitis C virus (HCV) genotype 1 or 2 infection. HOMA–IR and Trx levels were compared with baseline values after phlebotomy in 23 patients.Results:  HOMA–IR and serum Trx levels were significantly correlated with disease stage (HOMA–IR, P < 0.00001; Trx, P < 0.0001) and independently predicted fibrosis scores (HOMA–IR, P < 0.05; Trx, P < 0.005). Steatosis (%) was significantly correlated with HOMA–IR (P < 0.00005) and Trx (P < 0.001) stage (P < 0.00001). Serum Trx levels were significantly correlated with HOMA–IR (P < 0.05), even after adjustment for body mass index (P < 0.05). Furthermore, the mRNA levels of hepatic Trx were significantly correlated with HOMA–IR (P < 0.05) and independently‐predicted HOMA–IR (P < 0.05). The alanine aminotransferase (P < 0.00001), Trx (P < 0.05), and HOMA–IR (P < 0.05) serum levels decreased significantly after phlebotomy; these effects were similar even in non‐responders to interferon.Conclusion:  Oxidative stress contributed to the development of IR irrespective of obesity in patients with HCV genotype 1 or 2 infection. This study could contribute to our understanding of how metabolic disorders develop and how they should be treated in chronic hepatitis C patients.
Intrahepatic status of regulatory T cells in autoimmune liver diseases and chronic viral hepatitis
Authors: Sakaki Masashi , Hiroishi Kazumasa , Baba Toshiyuki , Ito Takayoshi , Hirayama Yuichi , Saito Koji , Tonoike Takahiko , Kushima Miki , Imawari Michio 
Published: November 2007

Aim:  Regulatory T cells (Tregs) maintain immunological tolerance and suppress autoreactive immune responses. We evaluated the intrahepatic status of Tregs in patients with autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), chronic hepatitis C (CH‐C), or chronic hepatitis B (CH‐B).Methods:  We analyzed 85 patients (20 AIH, 22 PBC, 27 CH‐C, and 16 CH‐B) and 14 controls. Using liver tissue samples obtained by needle biopsy or from marginal parts of resected metastatic liver tumors in the controls, immunohistochemical analyses of forkhead box P3+, which is a specific marker for Tregs, CD4+, and CD8+ cells were performed.Results:  Intrahepatic Tregs were significantly more infiltrated in patients with liver diseases than in the controls. There were significantly fewer intrahepatic Tregs in the AIH patients than in the PBC patients (P = 0.037). Patients with alow frequency of intrahepatic Tregs were detected significantly more in the AIH and CH‐B groups than in the PBC and CH‐C groups (P < 0.05). In addition, the frequency of Tregs decreased in the liver of PBC patients as the pathological stage of the disease advanced. We found significantly less infiltration of CD4+ T cells in AIH than in other diseases (P < 0.05). Liver‐infiltrating CD8+ T cells were detected more frequently in the CH‐B group than in other groups (P < 0.003).Conclusion:  Intrahepatic Tregs were increased in both patients with autoimmune liver diseases and those with viral hepatitis. In autoimmune liver diseases, intrahepatic Tregs were fewer in the AIH patients than in the PBC patients.
Assessment of nutritional status of patients with hepatitis C virus‐related liver cirrhosis
Authors: Kawabe Naoto , Hashimoto Senju , Harata Masao , Nitta Yoshifumi , Murao Michihito , Nakano Takuji , Shimazaki Hiroaki , Kobayashi Kyoko , Komura Naruomi , Ito Hiroko , Niwa Asako , Narita Wakana , Hanashita Junko , Ikeda Ayako , Yoshioka Kentaro 
Published: November 2007

Aim:  Nutrition support for patients with liver cirrhosis, such as late evening snacks and branched‐chain amino acids, has been demonstrated to be effective. However, the assessment of the malnutrition of liver cirrhosis is still a problem. The aim of this study was to assess the nutritional status of patients with liver cirrhosis due to hepatitis C virus by six methods and to test the sensitivity and specificity of these methods.Methods:  In total, 86 patients with liver cirrhosis due to hepatitis C virus were assessed for nutritional status by triceps skinfold thickness (TSF), arm muscle circumference (AMC), subjective global assessment (SGA), nutritional risk index (NRI), Maastricht index (MI), and instant nutritional assessment (INA).Results:  Malnutrition was found in 11 (12.8%) patients by TSF, 15 (17.4%) by AMC, 22 (25.6%) by SGA, 52 (60.5%) by the NRI, 66 (76.7%) by the MI, and in 54 (62.8%) by INA. The MI detected malnutrition at a significantly higher rate compared with the other five methods. Sixty‐two patients were diagnosed as malnourished by the combined index, which defines the patients as malnourished when any two of the NRI, MI, and INA also define them as malnourished. The misclassification rate compared with the combined indexes was significantly lower in the MI (4.7%) than in any of the TSF (59.3%), AMC (59.3%), SGA (46.5%), NRI (16.3%), and INA (14.0%).Conclusion:  The MI was the best single score to identify the patients who had malnutrition, including early stage, and may benefit from nutrition support.
Bacterial Community Composition in Central European Running Waters Examined by Temperature Gradient Gel Electrophoresis and Sequence Analysis of 16S rRNA Genes
Authors: Beier Sara , Witzel Karl-Paul , Marxsen Jürgen 
Published: November 2007

ABSTRACTThe bacterial community composition in small streams and a river in central Germany was examined by temperature gradient gel electrophoresis (TGGE) with PCR products of 16S rRNA gene fragments and sequence analysis. Complex TGGE band patterns suggested high levels of diversity of bacterial species in all habitats of these environments. Cluster analyses demonstrated distinct differences among the communities in stream and spring water, sandy sediments, biofilms on stones, degrading leaves, and soil. The differences between stream water and sediment were more significant than those between sites within the same habitat along the stretch from the stream source to the mouth. TGGE data from an entire stream course suggest that, in the upper reach of the stream, a special suspended bacterial community is already established and changes only slightly downstream. The bacterial communities in water and sediment in an acidic headwater with a pH below 5 were highly similar to each other but deviated distinctly from the communities at the other sites. As ascertained by nucleotide sequence analysis, stream water communities were dominated byBetaproteobacteria(one-third of the total bacteria), whereas sediment communities were composed mainly ofBetaproteobacteriaand members of theFibrobacteres/Acidobacteriagroup (each accounting for about 25% of bacteria). Sequences obtained from bacteria from water samples indicated the presence of typical cosmopolitan freshwater organisms. TGGE bands shared between stream and soil samples, as well as sequences found in bacteria from stream samples that were related to those of soil bacteria, demonstrated the occurrence of some species in both stream and soil habitats. Changes in bacterial community composition were correlated with geographic distance along a stream, but in comparisons of different streams and rivers, community composition was correlated only with environmental conditions.
Genomic Markers for Differentiation of
Francisella tularensis
subsp.
tularensis
A.I and A.II Strains
Authors: Molins-Schneekloth Claudia R. , Belisle John T. , Petersen Jeannine M. 
Published: November 2007

ABSTRACT

Tularemia is caused by two subspecies of
Francisella tularensis
,
F. tularensis
subsp.
tularensis
(type A) and
F. tularensis
subsp.
holarctica
(type B).
F. tularensis
subsp.
tularensis
is further subdivided into two genetically distinct populations (A.I and A.II) that differ with respect to geographical location, anatomical source of recovered isolates, and disease outcome. Using two human clinical isolates, suppression subtractive hybridization was performed to identify 13 genomic regions of difference between A.I and A.II strains. Two PCR assays, one to identify A.I and A.II as well as to discriminate between
F. tularensis
subsp.
holarctica
and
F. novicida
and another specific for A.I, were developed. This is the first report to identify and characterize conserved genomic differences between A.I and A.II.
Salmonella enterica
Burden in Harvest-Ready Cattle Populations from the Southern High Plains of the United States
Authors: Kunze David J. , Loneragan Guy H. , Platt Tammy M. , Miller Mark F. , Besser Thomas E. , Koohmaraie Mohammad , Stephens Tyler , Brashears Mindy M. 
Published: November 2007

ABSTRACT

Our objectives were to quantify the
Salmonella enterica
burdens in harvest-ready cattle and to identify specific at-risk populations of cattle most likely to harbor multiply resistant
S. enterica
. Hide swabs were collected in abattoirs from three cohorts of cattle (feedlot origin cattle that had achieved desirable harvest characteristics and dairy- and beef-type cows harvested because of poor productivity). Feces were collected from two cohorts housed in feedlots (cattle that had achieved desirable harvest characteristics and animals identified for salvage recovery because of poor productivity). Facilities were visited on four occasions over a 12-month period.
Salmonella enterica
isolates were recovered, and organisms were quantified using standard microbiological methodologies. Susceptibility to antimicrobial drugs and serotype were determined for one
S. enterica
isolate per sample.
Salmonella enterica
was recovered from 55.6% of 1,681 samples. The prevalences on hides and in feces were 69.6% and 30.3%, respectively. The concentrations of
S. enterica
organisms averaged (as determined by the most probable number technique) 1.82 log
10
/100 cm
2
of hides and 0.75 log
10
/g of feces. None of the isolates recovered from cattle that had achieved desirable harvest characteristics were resistant to four or more drugs. For isolates recovered from animals with poor productivity characteristics, 6.5% were resistant to four or more drugs. Twenty-two serovars were identified, with the most common being
Salmonella enterica
serovar Anatum (25.5%),
Salmonella enterica
serovar Montevideo (22.2%), and
Salmonella enterica
serovar Cerro (12.5%). High-level resistance, i.e., resistance to four or more drugs, was clustered within a few relatively uncommon serovars. These results demonstrate that even though
S. enterica
isolates are readily recoverable from harvest-ready cattle, multiply resistant variants are rare and are associated with specific serovars in cattle harvested because of poor productivity characteristics.
Unique Structural Features of the Peptidoglycan ofMycobacterium leprae
Authors: Mahapatra Sebabrata , Crick Dean C. , McNeil Michael R. , Brennan Patrick J. 
Published: November 2007

ABSTRACTThe peptidoglycan structure ofMycobacteriumspp. has been investigated primarily with the readily cultivableMycobacterium smegmatisandMycobacterium tuberculosisand has been shown to contain unusual features, including the occurrence of N-glycolylated, in addition to N-acetylated, muramic acid residues and direct cross-linkage betweenmeso-diaminopimelic acid residues. Based on results from earlier studies, peptidoglycan from in vivo-derived noncultivableMycobacterium lepraewas assumed to possess the basic structural features of peptidoglycans from other mycobacteria, other than the reported replacement ofl-alanine by glycine in the peptide side chains. In the present study, we have analyzed the structure ofM. lepraepeptidoglycan in detail by combined liquid chromatography and mass spectrometry. In contrast to earlier reports, and to the peptidoglycans inM. tuberculosisandM. smegmatis, the muramic acid residues ofM. lepraepeptidoglycan are exclusively N acetylated. The un-cross-linked peptide side chains ofM. lepraeconsist of tetra- and tripeptides, some of which contain additional glycine residues. Based on these findings and genome comparisons, it can be concluded that the massive genome decay inM. lepraedoes not markedly affect the peptidoglycan biosynthesis pathway, with the exception of the nonfunctionalnamHgene responsible forN-glycolylmuramic acid biosynthesis.
LuxS Affects Flagellar Phase Variation Independently of Quorum Sensing inSalmonella entericaSerovar Typhimurium
Authors: Karavolos M. H. , Bulmer D. M. , Winzer K. , Wilson M. , Mastroeni P. , Williams P. , Khan C. M. A. 
Published: November 2007

ABSTRACTLuxS catalyzes the synthesis of the quorum-sensing signaling molecule autoinducer 2. We show that inSalmonella entericaserovar Typhimurium, deletion of theluxSgene polarizes flagellar phase variation toward the more immunogenic phase 1 flagellin. This phenotype is complementable byluxSintransbut is independent of quorum-sensing signals.
Regulation of Motility by the ExpR/Sin Quorum-Sensing System in
Sinorhizobium meliloti
Authors: Hoang Hanh H. , Gurich Nataliya , González Juan E. 
Published: November 2007

ABSTRACT

A successful symbiotic relationship between
Sinorhizobium meliloti
and its host
Medicago sativa
(alfalfa) depends on several signaling mechanisms, such as the biosynthesis of exopolysaccharides (EPS) by
S. meliloti
. Previous work in our laboratory has shown that a quorum-sensing mechanism controls the production of the symbiotically active EPS II. Recent microarray analysis of the whole-genome expression profile of
S. meliloti
reveals that the ExpR/Sin quorum-sensing system regulates additional physiological processes that include low-molecular-weight succinoglycan production, nitrogen utilization, metal transport, motility, and chemotaxis. Nearly half of the flagellar genes and their dependence on quorum sensing are prominently displayed in our microarray analyses. We extend those observations in this work and confirm the findings by real-time PCR expression analysis of selected genes, including the
flaF, flbT, flaC, cheY1
, and
flgB
genes, involved in motility and chemotaxis. These genes code for regulators of flagellum synthesis, the chemotactic response, or parts of the flagellar apparatus. Gene expression analyses and visualization of flagella by electron microscopy performed at different points in the growth phase support our proposed model in which quorum sensing downregulates motility in
S. meliloti
. We demonstrate that the ExpR/Sin quorum-sensing system controls motility gene expression through the VisN/VisR/Rem relay. We also show that the ExoS-dependent two-component system suppresses motility gene expression through VisN and Rem in parallel to quorum sensing. This study contributes to our understanding of the mechanisms that govern motility in
S. meliloti
.