bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ameloblastic fibroma and related lesions: a clinicopathologic study with reference to their nature and interrelationship
Authors: Chen Yan , Li Tie‐Jun , Gao Yan , Yu Shi‐Feng 
Published: October 2005

Background:  Ameloblastic fibroma (AF) and related lesions constitute a group of lesions, which range in biologic behavior from true neoplasms to hamartomas. The aim of this study was to elucidate the nature and interrelationship of this group of lesions.Methods:  Clinical and pathological studies were undertaken retrospectively on 13 cases of AF and seven cases of ameloblastic fibro‐odontoma (AFO). Thirty‐three complex odontomas and 33 compound odontomas were also included for comparative purpose. Relevant follow‐up data were recorded and the literature was reviewed.Results:  The majority of patients with AF (nine cases, 69.2%) were over the age of 22 years with frequent involvement (76.9%) of the posterior mandible. Tumors recurred in four of 11 patients with follow‐up information and two recurrent tumors showed malignant transformation. There was no case in this series that could be designated as the so‐called ameloblastic fibrodentinoma, apart from one recurrent AF in which further maturation to form only tubular dentin materials was identified. AFO tended to occur at a younger age group with an average of 9.6 years. Recurrence was noted in two of five patients with follow‐up data and both recurrent lesions showed limited growth potential and further maturation into a complex odontoma. Significant differences were noted in the age and site distribution between the complex and the compound odontomas.Conclusion:  Whilst the majority, if not all, of AFs are true neoplasms with a potential to recur and/or of malignant transformation, some, especially those occurred during childhood, could represent the primitive stage of a developing odontoma. Our data also suggests that some AFOs are hamartomatous in nature, representing a stage preceding the complex odontoma.
Can Atorvastatin Improve the Response to Sildenafil in Men with Erectile Dysfunction Not Initially Responsive to Sildenafil? Hypothesis and Pilot Trial Results
Authors: Herrmann Howard C. , Levine Laurence A. , Macaluso Joseph , Walsh Michelle , Bradbury Danielle , Schwartz Stanley , Mohler Emile R. , Kimmel Stephen E. 
Published: October 2005

ABSTRACT

Background
Erectile dysfunction (ED) may be one manifestation of a generalized vascular disorder characterized by endothelial dysfunction. Statin drugs may improve endothelial function, even before altering the lipid profile.

Objective
We sought to determine whether the addition of a statin with sildenafil would improve ED in men who initially responded poorly to sildenafil.

Methods
Men with moderate-to-severe ED despite an adequate sildenafil trial were enrolled in this randomized, double-blind, placebo-controlled pilot study. ED was defined using a validated self-administered questionnaire as a score of ≤16 on the International Index of Erectile Function (erectile function domain score range of 6–30). Improvement in ED score with sildenafil was reassessed at 6 and 12 weeks of treatment with atorvastatin (80 mg daily) or matching placebo.

Results
Twelve men (mean age 58 ± 13 years) with a mean domain score of 8.2 ± 6.9 and a mean duration of ED of 3.7 years were enrolled in the study. Treatment with atorvastatin decreased mean low-density lipoprotein cholesterol by 43% and resulted in an improvement with sildenafil in domain score of 7.8 (P = 0.036); an effect was apparent by 6 weeks. The increase in domain score in placebo patients was not statistically significant.

Conclusions
Treatment with atorvastatin improved sexual function and the response to oral sildenafil in men who did not initially respond to treatment with sildenafil. The results of this pilot study support the hypothesis that vascular endothelial dysfunction contributes to ED in sildenafil nonresponders and deserves further testing in a large clinical trial.
Functional Sequelae of Cavernous Nerve Injury in the Rat: Is There Model Dependency
Authors: Mullerad Michael , Donohue John F. , Li Philip S. , Scardino Peter T. , Mulhall John P. 
Published: October 2005

ABSTRACT

Introduction
The rat model of cavernous nerve (CN) injury has been developed in an effort to define the functional and structural consequences of neural trauma in the corpus cavernosum. However, there is no universally accepted method of inducing nerve injury in this model, with neurotomy and crush models being used currently. To address this issue, we induced CN injury using various techniques in an effort to compare the hemodynamic sequelae of these injuries.

Methods
Twenty-five adult male Sprague–Dawley rats were divided into five groups: (1) control: laparotomy only; (2) exposure: laparotomy and exposure of cavernous nerves bilaterally without nerve manipulation; (3) neurotomy; bilateral neurotomy; (4) bulldog crush: bilateral nerve crush with bulldog vascular clamp; and (5) hemostat nerve crush: bilateral nerve crush with a hemostat. Ten days later, a second operation was performed during which systemic mean arterial pressure (MAP) and intracavernosal pressure (ICP) were measured in response to CN stimulation proximal to the site of injury. Hemodynamic endpoints assessed included ICP/MAP ratio, rate of tumescence, and rate of detumescence.

Results
The ICP/MAP ratio (mean ± 95% confidence interval) in the control group was 70 ± 4%. ICP/MAP ratios were significantly reduced in all CN injury groups compared with control group: exposure: 41 ± 10% (P &lt; 0.001); neurotomy: 35 ± 15% (P &lt; 0.001); bulldog crush: 39 ± 13% (P &lt; 0.001); hemostat crush: 31 ± 9% (P &lt; 0.0001). No significant difference existed in ICP/MAP ratios between the injury groups. Of note, the exposure group also demonstrated significant functional alterations. The rates of tumescence and detumescence were significantly reduced in all groups compared with the control group.

Conclusion
No significant difference in the magnitude and consistency of hemodynamic alterations has been demonstrated in all CN injury models assessed in this study.
Ultrasonic measurement of third-order elastic constants of fused silica
Authors: Breazeale M. A. , Fischer M. 
Published: October 2005

A finite amplitude ultrasonic wave propagating through a solid generates harmonics whose magnitudes are determined by some of the third-order elastic constants. Other third-order elastic constants determine the magnitude of the variation of ultrasonic wave velocity as the sample is subjected to hydrostatic pressure. We have combined results of harmonic generation experiments and pressure variation of ultrasonic wave velocity to evaluate third-order elastic constants of fused silica. We used four different samples having different hydroxyl ion content and different homogeneities and obtained the following results.
OH
content C111 C112 C123
Sample (ppm) (1012 dyn/cm 2) (1012 dyn/cm 2) (1012 dyn/cm 2)
Suprasil W1 5 6.70 ± 0.12 1.81 ± 0.09 1.77 ± 0.16
Suprasil W2 5 6.85 ± 0.06 1.64 ± 0.06 1.59 ± 0.12
Suprasil 1 1200 7.31 ± 0.07 1.69 ± 0.14 2.16 ± 0.11
Suprasil 2 1200 6.75 ± 0.07 1.79 ± 0.07 1.80 ± 0.11
The relationship between these results and results available from other techniques is discussed. [Research supported by the Office of Naval Research and by NATO.]
Application of the
Synechococcus nirA
Promoter To Establish an Inducible Expression System for Engineering the
Synechocystis
Tocopherol Pathway
Authors: Qi Qungang , Hao Ming , Ng Wing-on , Slater Steven C. , Baszis Susan R. , Weiss James D. , Valentin Henry E. 
Published: October 2005

ABSTRACT

Tocopherols are important antioxidants in lipophilic environments. They are synthesized by plants and some photosynthetic bacteria. Recent efforts to analyze and engineer tocopherol biosynthesis led to the identification of
Synechocystis
sp. strain PCC 6803 as a well-characterized model system. To facilitate the identification of the rate-limiting step(s) in the tocopherol biosynthetic pathway through the modulation of transgene expression, we established an inducible expression system in
Synechocystis
sp. strain PCC 6803. The
nirA
promoter from
Synechococcus
sp. strain PCC 7942, which is repressed by ammonium and induced by nitrite (S.-I. Maeda et al., J. Bacteriol. 180:4080-4088, 1998), was chosen to drive the expression of
Arabidopsis thaliana p-
hydroxyphenylpyruvate dioxygenase. The enzyme catalyzes the formation of homogentisic acid from
p-
hydroxyphenylpyruvate. Expression of this gene under inducing conditions resulted in up to a fivefold increase in total tocopherol levels with up to 20% of tocopherols being accumulated as tocotrienols. The culture supernatant of these cultures exhibited a brown coloration, a finding indicative of homogentisic acid excretion. Enzyme assays, functional complementation, reverse transcription-PCR, and Western blot analysis confirmed transgene expression under inducing conditions only. These data demonstrate that the
nirA
promoter can be used to control transgene expression in
Synechocystis
and that homogentisic acid is a limiting factor for tocopherol synthesis in
Synechocystis
sp. strain PCC 6803.
Mycobacterial Ecology of the Rio Grande
Authors: Bland Christopher S. , Ireland Jamie M. , Lozano Eduardo , Alvarez Maria E. , Primm Todd P. 
Published: October 2005

ABSTRACT

This is the first study to characterize the environmental conditions which contribute to the presence and proliferation of environmental mycobacteria in a major freshwater river. Over 20 different species of environmental mycobacteria were isolated, including the pathogenic
M. avium
and
M. kansasii
. Species of the rapidly growing
M. fortuitum
complex were the most commonly isolated mycobacteria, and one-third of all isolates were not identified at the species level, even by 16S sequencing. PCR restriction analysis of the
hsp65
gene was more accurate and rapid than biochemical tests and as accurate as yet less expensive than 16S sequencing, showing great promise as a new tool for species identification of environmentally isolated mycobacteria. Total environmental mycobacteria counts positively correlated with coliform and
Escherichia coli
counts and negatively correlated with chemical toxicity and water temperature. Environmental mycobacteria can survive in the alkaline conditions of the river despite previous reports that especially acidic conditions favor their presence. A representative river isolate (
M. fortuitum
) survived better than
E. coli
O157:H7 at pHs below 7 and above 8 in nutrient broth. The river strain also retained viability at 8 ppm of free chlorine, while
E. coli
was eliminated at 2 ppm and above. Thus, in vitro studies support environmental observations that a variety of extreme conditions favor the hardy environmental mycobacteria.
Directed Evolution of a Thermostable Phosphite Dehydrogenase for NAD(P)H Regeneration
Authors: Johannes Tyler W. , Woodyer Ryan D. , Zhao Huimin 
Published: October 2005

ABSTRACT

NAD(P)H-dependent oxidoreductases are valuable tools for synthesis of chiral compounds. The expense of the cofactors, however, requires in situ cofactor regeneration for preparative applications. We have attempted to develop an enzymatic system based on phosphite dehydrogenase (PTDH) from
Pseudomonas stutzeri
to regenerate the reduced nicotinamide cofactors NADH and NADPH. Here we report the use of directed evolution to address one of the main limitations with the wild-type PTDH enzyme, its low stability. After three rounds of random mutagenesis and high-throughput screening, 12 thermostabilizing amino acid substitutions were identified. These 12 mutations were combined by site-directed mutagenesis, resulting in a mutant whose
T
50
is 20°C higher and half-life of thermal inactivation at 45°C is >7,000-fold greater than that of the parent PTDH. The engineered PTDH has a half-life at 50°C that is 2.4-fold greater than the
Candida boidinii
formate dehydrogenase, an enzyme widely used for NADH regeneration. In addition, its catalytic efficiency is slightly higher than that of the parent PTDH. Various mechanisms of thermostabilization were identified using molecular modeling. The improved stability and effectiveness of the final mutant were shown using the industrially important bioconversion of trimethylpyruvate to
l
-
tert
-leucine. The engineered PTDH will be useful in NAD(P)H regeneration for industrial biocatalysis.
Integrated Recombinant Protein Expression and Purification Platform Based on
Ralstonia eutropha
Authors: Barnard Gavin C. , McCool Jesse D. , Wood David W. , Gerngross Tillman U. 
Published: October 2005

ABSTRACT

Protein purification of recombinant proteins constitutes a significant cost of biomanufacturing and various efforts have been directed at developing more efficient purification methods. We describe a protein purification scheme wherein
Ralstonia eutropha
is used to produce its own “affinity matrix,” thereby eliminating the need for external chromatographic purification steps. This approach is based on the specific interaction of phasin proteins with granules of the intracellular polymer polyhydroxybutyrate (PHB). By creating in-frame fusions of phasins and green fluorescent protein (GFP) as a model protein, we demonstrated that GFP can be efficiently sequestered to the surface of PHB granules. In a second step, we generated a phasin-intein-GFP fusion, wherein the self-cleaving intein can be activated by the addition of thiols. This construct allowed for the controlled binding and release of essentially pure GFP in a single separation step. Finally, pure, active β-galactosidase was obtained in a single step using the above described method.
Identification and Characterization of Di- and Tripeptide Transporter DtpT of
Listeria monocytogenes
EGD-e
Authors: Wouters Jeroen A. , Hain Torsten , Darji Ajub , Hüfner Eric , Wemekamp-Kamphuis Henrike , Chakraborty Trinad , Abee Tjakko 
Published: October 2005

ABSTRACT

Listeria monocytogenes
is a gram-positive intracellular pathogen responsible for opportunistic infections in humans and animals. Here we identified and characterized the
dtpT
gene (lmo0555) of
L. monocytogenes
EGD-e, encoding the di- and tripeptide transporter, and assessed its role in growth under various environmental conditions as well as in the virulence of
L. monocytogenes
. Uptake of the dipeptide Pro-[
14
C]Ala was mediated by the DtpT transporter and was abrogated in a Δ
dtpT
isogenic deletion mutant. The DtpT transporter was shown to be required for growth when the essential amino acids leucine and valine were supplied as peptides. The protective effect of glycine- and proline-containing peptides during growth in defined medium containing 3% NaCl was noted only in
L. monocytogenes
EGD-e, not in the Δ
dtpT
mutant strain, indicating that the DtpT transporter is involved in salt stress protection. Infection studies showed that DtpT contributes to pathogenesis in a mouse infection model but has no role in bacterial growth following infection of J774 macrophages. These studies reveal that DptT may contribute to the virulence of
L. monocytogenes
.
Vertical and Seasonal Variations of Bacterioplankton Subgroups with Different Nucleic Acid Contents: Possible Regulation by Phosphorus
Authors: Nishimura Yoko , Kim Chulgoo , Nagata Toshi 
Published: October 2005

ABSTRACT

We used flow cytometry to examine seasonal variations in basin-scale distributions of bacterioplankton in Lake Biwa, Japan, a large mesotrophic freshwater lake with an oxygenated hypolimnion. The bacterial communities were divided into three subgroups: bacteria with very high nucleic acid contents (VHNA bacteria), bacteria with high nucleic acid contents (HNA bacteria), and bacteria with low nucleic acid contents (LNA bacteria). During the thermal stratification period, the relative abundance of VHNA bacteria (%VHNA) increased with depth, while the reverse trend was evident for LNA bacteria. Seasonally, the %VHNA was strongly positively correlated (
r
= 0.87;
P
< 0.001) with the concentration of dissolved inorganic phosphorus, but not with the concentration of chlorophyll
a
. The growth of VHNA bacteria was significantly enhanced by addition of phosphate or phosphate plus glucose but not by addition of glucose alone. Although the growth of VHNA and HNA bacteria generally exceeded that of LNA bacteria, our data also revealed that LNA bacteria grew faster than and were grazed as fast as VHNA bacteria in late August, when nutrient limitation was presumably severe. Based on these results, we hypothesize that in severely P-limited environments such as Lake Biwa, P limitation exerts more severe constraints on the growth of bacterial groups with higher nucleic acid contents, which allows LNA bacteria to be competitive and become an important component of the microbial loop.
Development of a Method for Markerless Genetic Exchange in
Enterococcus faecalis
and Its Use in Construction of a
srtA
Mutant
Authors: Kristich Christopher J. , Manias Dawn A. , Dunny Gary M. 
Published: October 2005

ABSTRACT

Enterococcus faecalis
is a gram-positive commensal bacterium of the gastrointestinal tract and an important opportunistic pathogen. Despite the increasing clinical significance of the enterococci, genetic analysis of these organisms has thus far been limited in scope due to the lack of advanced genetic tools. To broaden the repertoire of genetic tools available for manipulation of
E.faecalis
, we investigated the use of phosphoribosyl transferases as elements of a counterselection strategy. We report here the development of a counterselectable markerless genetic exchange system based on the
upp
-encoded uracil phosphoribosyl transferase of
E. faecalis
. Whereas wild-type
E. faecalis
is sensitive to growth inhibition by the toxic base analog 5-fluorouracil (5-FU), a mutant bearing an in-frame deletion of
upp
is resistant to 5-FU. When a cloned version of
upp
was ectopically introduced into the deletion mutant, sensitivity to 5-FU growth inhibition was restored, thereby providing the basis for a two-step integration and excision strategy for the transfer of mutant alleles to the enterococcal chromosome by recombination. This method was validated by the construction of a Δ
srtA
mutant of
E. faecalis
and by the exchange of the surface protein Asc10, encoded on the pheromone-responsive conjugative plasmid pCF10, with a previously isolated mutant allele. Analysis of the Δ
srtA
mutant indicated that SrtA anchors Asc10 to the enterococcal cell wall, facilitating the pheromone-induced aggregation of
E. faecalis
cells required for high-frequency conjugative plasmid transfer in liquid matings. The system of markerless exchange reported here will facilitate detailed genetic analysis of these important pathogens.
Genetic Diversity of Small Eukaryotes in Lakes Differing by Their Trophic Status
Authors: Lefranc Marie , Thénot Aurélie , Lepère Cécile , Debroas Didier 
Published: October 2005

ABSTRACT
Small eukaryotes, cells with a diameter of less than 5 μm, are fundamental components of lacustrine planktonic systems. In this study, small-eukaryote diversity was determined by sequencing cloned 18S rRNA genes in three libraries from lakes of differing trophic status in the Massif Central, France: the oligotrophic Lake Godivelle, the oligomesotrophic Lake Pavin, and the eutrophic Lake Aydat. This analysis shows that the least diversified library was in the eutrophic lake (12 operational taxonomic units [OTUs]) and the most diversified was in the oligomesotrophic lake (26 OTUs). Certain groups were present in at least two ecosystems, while the others were specific to one lake on the sampling date. Cryptophyta, Chrysophyceae, and the strictly heterotrophic eukaryotes, Ciliophora and fungi, were identified in the three libraries. Among the small eukaryotes found only in two lakes, Choanoflagellida and environmental sequences (LKM11) were not detected in the eutrophic system whereas Cercozoa were confined to the oligomesotrophic and eutrophic lakes. Three OTUs, linked to the Perkinsozoa, were detected only in the Aydat library, where they represented 60% of the clones of the library. Chlorophyta and Haptophyta lineages were represented by a single clone and were present only in Godivelle and Pavin, respectively. Of the 127 clones studied, classical pigmented organisms (autotrophs and mixotrophs) represented only a low proportion regardless of the library's origin. This study shows that the small-eukaryote community composition may differ as a function of trophic status; certain lineages could be detected only in a single ecosystem.
Effects of Dichloroethene Isomers on the Induction and Activity of Butane Monooxygenase in the Alkane-Oxidizing Bacterium “
Pseudomonas butanovora
”
Authors: Doughty D. M. , Sayavedra-Soto L. A. , Arp D. J. , Bottomley P. J. 
Published: October 2005

ABSTRACT

We examined cooxidation of three different dichloroethenes (1,1-DCE, 1,2-
trans
DCE, and 1,2-
cis
DCE) by butane monooxygenase (BMO) in the butane-utilizing bacterium “
Pseudomonas butanovora
.” Different organic acids were tested as exogenous reductant sources for this process. In addition, we determined if DCEs could serve as surrogate inducers of BMO gene expression. Lactic acid supported greater rates of oxidation of the three DCEs than the other organic acids tested. The impacts of lactic acid-supported DCE oxidation on BMO activity differed among the isomers. In intact cells, 50% of BMO activity was irreversibly lost after consumption of ∼20 nmol mg protein
−1
of 1,1-DCE and 1,2-
trans
DCE in 0.5 and 5 min, respectively. In contrast, a comparable loss of activity required the oxidation of 120 nmol 1,2-
cis
DCE mg protein
−1
. Oxidation of similar amounts of each DCE isomer (∼20 nmol mg protein
−1
) produced different negative effects on lactic acid-dependent respiration. Despite 1,1-DCE being consumed 10 times faster than 1,2,-
trans
DCE, respiration declined at similar rates, suggesting that the product(s) of oxidation of 1,2-
trans
DCE was more toxic to respiration than 1,1-DCE. Lactate-grown “
P. butanovora
” did not express BMO activity but gained activity after exposure to butane, ethene, 1,2-
cis
DCE, or 1,2-
trans
DCE. The products of BMO activity, ethene oxide and 1-butanol, induced
lac
Z in a reporter strain containing
lac
Z fused to the BMO promoter, whereas butane, ethene, and 1,2-
cis
DCE did not. 1,2-
trans
DCE was unique among the BMO substrates tested in its ability to induce
lac
Z expression.
Alternative Lactose Catabolic Pathway in
Lactococcus lactis
IL1403
Authors: Aleksandrzak-Piekarczyk Tamara , Kok Jan , Renault Pierre , Bardowski Jacek 
Published: October 2005

ABSTRACT

In this study, we present a glimpse of the diversity of
Lactococcus lactis
subsp.
lactis
IL1403
β
-galactosidase phenotype-negative mutants isolated by negative selection on solid media containing cellobiose or lactose and X-Gal (5-bromo-4-chloro-3-indolyl-β-
d
-galactopyranoside), and we identify several genes essential for lactose assimilation. Among these are
ccpA
(encoding catabolite control protein A),
bglS
(encoding phospho-
β
-glucosidase), and several genes from the Leloir pathway gene cluster encoding proteins presumably essential for lactose metabolism. The functions of these genes were demonstrated by their disruption and testing of the growth of resultant mutants in lactose-containing media. By examining the
ccpA
and
bglS
mutants for phospho-
β
-galactosidase activity, we showed that expression of
bglS
is not under strong control of CcpA. Moreover, this analysis revealed that although BglS is homologous to a putative phospho-
β
-glucosidase, it also exhibits phospho-
β
-galactosidase activity and is the major enzyme in
L. lactis
IL1403 involved in lactose hydrolysis.