bluuebunny/crossref_metadata_2025_split huggingface dataset:
Five‐year results following treatment of intrabony defects with enamel matrix proteins and guided tissue regeneration
Authors: Sculean Anton , Donos Nicolaos , Schwarz Frank , Becker Jürgen , Brecx Michel , Arweiler Nicole B. 
Published: June 2004

AbstractBackground: Treatment with enamel matrix proteins (EMD) or guided tissue regeneration (GTR) has been shown to enhance periodontal regeneration. However, until now there are limited data on the long‐term results following these treatment modalities.Aim: The aim of the present clinical study was to present the 5‐year results following treatment of intrabony defects with EMD, GTR, combination of EMD and GTR, and open flap debridement (OFD).Material and Methods: Forty‐two patients, each of whom displayed one intrabony defect of a probing depth of at least 6 mm, were randomly treated with one of the four treatment modalities. The following parameters were evaluated prior to surgery, at 1 year and at 5 years after: plaque index, gingival index, bleeding on probing, probing pocket depth (PPD), gingival recession, and clinical attachment level (CAL). No statistically significant differences in any of the parameters were observed at baseline between the four groups.Results: The sites treated with EMD demonstrated a mean CAL gain of 3.4±1.1 mm (p<0.001) and of 2.9±1.6 mm (p<0.001) at 1 and 5 years, respectively. The sites treated with GTR showed a mean CAL gain of 3.2±0.8 (p<0.001) at 1 year and of 2.7±0.9 mm (p<0.001) at 5 years. The mean CAL gain at sites treated with EMD+GTR was 3.0±1.0 mm (p<0.001) and 2.6±0.7 mm (p<0.001) at 1 and 5 years, respectively. The sites treated with OFD demonstrated a mean CAL gain of 1.6±1.0 mm (p<0.001) at 1 year and 1.3±1.2 mm (p<0.001) at 5 years. At 1 year, the only statistically significant difference between the four different treatments was found in terms of PPD reduction and CAL gain between EMD and OFD (p<0.05). However, at 5 years there were no statistically significant differences in any of the investigated parameters between the four different treatments.Conclusion: Within the limits of the present study, it may be concluded that the short‐term clinical results following treatment with EMD, GTR, EMD+GTR, and OFD can be maintained over a period of 5 years.
Histologic evaluation of demineralized freeze‐dried bone allografts in barrier membrane covered periodontal fenestration wounds and ectopic sites in dogs
Authors: Klepp Morten , Hinrichs James E. , Eastlund Ted , Schaffer Erwin M. 
Published: June 2004

AbstractBackground/Aim: The aim of this study was to investigate healing responses to demineralized freeze‐dried bone powder allografts in standardized periodontal fenestration defects, compared with subcutaneous wounds in a dog model.Methods: Circular periodontal fenestration defects were created buccally at all four canines in 14 mongrel dogs. Each site received one of the following underneath a barrier membrane: (a) ethylene oxide (EO)‐sterilized demineralized freeze‐dried bone allografts (DFDBA), (b) heat‐treated DFDBA, (c) non‐sterilized DFDBA and (d) ungrafted control. Twelve of the 14 dogs had three subcutaneous chest wall pouches created and one of the three DFDBA materials placed in each. The animals were necropsied at 4 weeks. Histologic sections were prepared through the center of the fenestration sites in an apico‐coronal direction. Quantitative analysis using computer‐assisted imaging technique was performed. Subcutaneous implants were evaluated histologically and quantified for associated inflammatory cell infiltrate.Results: Fenestration defects healed by partial osseous fill and cementum regeneration with formation of a periodontal ligament. The graft particles generally appeared isolated from the site of osteogenesis and covered by cementum‐like substance. Graft particles incorporated into newly formed bone at a distance from the root surface was the exception. No statistically significant differences in new bone formation were observed between treatment groups within animals, but significant inter‐animal variation was found (p<0.01). Quantities of retained graft particles were limited, and without cellular resorption. A bone augmentation effect was associated with the barrier in the majority of sites. No bone formation was evident at the subcutaneous sites where graft particles displayed distinctly modified surface zones and multinucleated giant cell resorption. Significantly more inflammatory infiltrate was associated with EO‐sterilized grafts compared with heat‐treated grafts (p=0.05).Conclusion: Implantation of DFDBA neither enhanced osseous healing in periodontal fenestration defects, nor resulted in ectopic bone induction. DFDBA particles implanted in either periodontal fenestration or subcutaneous wounds evoked distinctly different healing responses.
Post‐transplant lymphoproliferative disorders presenting as gingival overgrowth in patients immunosuppressed with ciclosporin. A report of two cases
Authors: Rolland S.L. , Seymour R.A. , Wilkins B.S. , Parry G. , Thomason J.M. 
Published: June 2004

AbstractBackground:Post‐transplant lymphoproliferative disorder (PTLD) can occur in patients maintained on immunosuppressive therapy following transplantation. This paper describes two cases of PTLD occurring in gingival tissues, in patients receiving ciclosporin following cardiac transplantation.Treatment:The lesions were localised to gingival tissues, mimicking ciclosporin‐induced gingival overgrowth. They were removed surgically and the ciclosporin dose reduced to help prevent recurrence.Conclusion:The importance of histopathological examination of all tissue removed during routine gingivectomy procedures for ciclosporin‐induced gingival overgrowth is highlighted.
Evidence that hsp90 Is Involved in the Altered Interactions ofAcanthamoeba castellaniiVariants with Bacteria
Authors: Yan Ling , Cerny Ronald L. , Cirillo Jeffrey D. 
Published: June 2004

ABSTRACTThere are many similarities between the interactions of environmental protozoa with pathogenic bacterial species and those observed in mammalian macrophages. Since single-celled protozoa predate mammalian hosts, it is likely that interactions in environmental biofilms have selected for many of the bacterial virulence mechanisms responsible for human disease. In order to better understand bacterial-phagocyte interactions, we developed a selection forAcanthamoeba castellaniivariants that are more resistant to killing by bacterial pathogens. We identified four amoebal clones that display decreased phagocytosis of bacteria but no difference in uptake of latex beads compared to wild-type amoebae. These amoebal variants display differences in cellular morphology, partial resistance to killing by bacteria, more bactericidal activity, and higher frequencies of lysosome fusion with the bacterial vacuole. Three proteins are present at lower levels in these variants than in wild-type amoebae, and matrix-assisted laser desorption ionization-time of flight mass spectrometry allowed identification of two of them as actin and hsp90. We found that specific inhibitors of hsp90 produce a similar phenotypic effect in macrophages. These data suggest that hsp90 plays a role in phagocytic and, possibly, bactericidal pathways that affect interactions of phagocytic cells with bacteria.
Novel Promoter Sequence Required for Manganese Regulation of Manganese Peroxidase Isozyme 1 Gene Expression in
Phanerochaete chrysosporium
Authors: Ma Biao , Mayfield Mary B. , Godfrey Bruce J. , Gold Michael H. 
Published: June 2004

ABSTRACT

Manganese peroxidase (MnP) is a major, extracellular component of the lignin-degrading system produced by the wood-rotting basidiomycetous fungus
Phanerochaete chrysosporium
. The transcription of MnP-encoding genes (
mnp
s) in
P. chrysosporium
occurs as a secondary metabolic event, triggered by nutrient-nitrogen limitation. In addition,
mnp
expression occurs only under Mn
2+
supplementation. Using a reporter system based on the enhanced green fluorescent protein gene (
egfp
), we have characterized the
P. chrysosporium mnp1
promoter by examining the effects of deletion, replacement, and translocation mutations on
mnp1
promoter-directed
egfp
expression. The 1,528-bp
mnp1
promoter fragment drives
egfp
expression only under Mn
2+
-sufficient, nitrogen-limiting conditions, as required for endogenous MnP production. However, deletion of a 48-bp fragment, residing 521 bp upstream of the translation start codon in the
mnp1
promoter, or replacement of this fragment with an unrelated sequence resulted in
egfp
expression under nitrogen limitation, both in the absence and presence of exogenous Mn
2+
. Translocation of the 48-bp fragment to a site 120 bp downstream of its original location resulted in Mn
2+
-dependent
egfp
expression under conditions similar to those observed with the wild-type
mnp1
promoter. These results suggest that the 48-bp fragment contains at least one Mn
2+
-responsive
cis
element. Additional promoter-deletion experiments suggested that the Mn
2+
element(s) is located within the 33-bp sequence at the 3′ end of the 48-bp fragment. This is the first promoter sequence containing a Mn
2+
-responsive element(s) to be characterized in any eukaryotic organism.
The Signal from the Initiation of Meiotic Recombination to the First Division of Meiosis
Authors: Malone Robert E. , Haring Stuart J. , Foreman Kelley E. , Pansegrau Morgan L. , Smith Sonja M. , Houdek Demelza R. , Carpp Lindsay , Shah Bijal , Lee KariAn E. 
Published: June 2004

ABSTRACT

Two of the unique events that occur in meiosis are high levels of genetic recombination and the reductional division. Our previous work demonstrated that the
REC102
,
REC104
,
REC114
, and
RAD50
genes, required to initiate meiotic recombination in
Saccharomyces cerevisiae
, are needed for the proper timing of the first meiotic (MI) division. If these genes are absent, the MI division actually begins at an earlier time. This paper demonstrates that the meiotic recombination genes
MER2/REC107
,
SPO11
, and
MRE2
and the synaptonemal complex genes
HOP1
and
RED1
are also required for the normal delay of the MI division. A
rec103/ski8
mutant starts the MI division at the same time as in wild-type cells. Our data indicate no obvious correlation between the timing of premeiotic S phase and the timing of the first division in Rec
−
mutants. Cells with
rec102
or
rec104
mutations form MI spindles before wild-type cells, suggesting that the initiation signal acts prior to spindle formation. Neither
RAD9
nor
RAD24
is needed to transduce the signal, which delays the first division. The timing of the MI division in
RAD24
mutants indicates that the pachytene checkpoint is not active in Rec
+
cells and suggests that the coordination between recombination and the MI division in wild-type cells may occur primarily due to the initiation signal. Finally, at least one of the targets of the recombination initiation signal is the
NDT80
gene, a transcriptional regulator of middle meiotic gene expression required for the first division.
The Kip3-Like Kinesin KipB Moves along Microtubules and Determines Spindle Position during Synchronized Mitoses in
Aspergillus nidulans
Hyphae
Authors: Rischitor Patricia E. , Konzack Sven , Fischer Reinhard 
Published: June 2004

ABSTRACT

Kinesins are motor proteins which are classified into 11 different families. We identified 11 kinesin-like proteins in the genome of the filamentous fungus
Aspergillus nidulans
. Relatedness analyses based on the motor domains grouped them into nine families. In this paper, we characterize KipB as a member of the Kip3 family of microtubule depolymerases. The closest homologues of KipB are
Saccharomyces cerevisiae
Kip3 and
Schizosaccharomyces pombe
Klp5 and Klp6, but sequence similarities outside the motor domain are very low. A disruption of
kipB
demonstrated that it is not essential for vegetative growth.
kipB
mutant strains were resistant to high concentrations of the microtubule-destabilizing drug benomyl, suggesting that KipB destabilizes microtubules.
kipB
mutations caused a failure of spindle positioning in the cell, a delay in mitotic progression, an increased number of bent mitotic spindles, and a decrease in the depolymerization of cytoplasmic microtubules during interphase and mitosis. Meiosis and ascospore formation were not affected. Disruption of the
kipB
gene was synthetically lethal in combination with the temperature-sensitive mitotic kinesin motor mutation
bimC4
, suggesting an important but redundant role of KipB in mitosis. KipB localized to cytoplasmic, astral, and mitotic microtubules in a discontinuous pattern, and spots of green fluorescent protein moved along microtubules toward the plus ends.
Multiple Functionally Redundant Signals Mediate Targeting to the Apicoplast in the Apicomplexan Parasite
Toxoplasma gondii
Authors: Harb Omar S. , Chatterjee Bithi , Fraunholz Martin J. , Crawford Michael J. , Nishi Manami , Roos David S. 
Published: June 2004

ABSTRACT

Most species of the protozoan phylum Apicomplexa harbor an endosymbiotic organelle—the apicoplast—acquired when an ancestral parasite engulfed a eukaryotic plastid-containing alga. Several hundred proteins are encoded in the parasite nucleus and are posttranslationally targeted to the apicoplast by a distinctive bipartite signal. The N-terminal 20 to 30 amino acids of nucleus-encoded apicoplast targeted proteins function as a classical signal sequence, mediating entry into the secretory pathway. Cleavage of the signal sequence exposes a transit peptide of variable length (50 to 200 amino acids) that is required for directing proteins to the apicoplast. Although these peptides are enriched in basic amino acids, their structural and functional characteristics are not well understood, which hampers the identification of apicoplast proteins that may constitute novel chemotherapeutic targets. To identify functional domains for a model apicoplast transit peptide, we generated more than 80 deletions and mutations throughout the transit peptide of
Toxoplasma gondii
ferredoxin NADP
+
reductase (TgFNR) and examined the ability of these altered transit peptides to mediate proper targeting and processing of a fluorescent protein reporter. These studies revealed the presence of numerous functional domains. Processing can take place at multiple sites in the protein sequence and may occur outside of the apicoplast lumen. The TgFNR transit peptide contains at least two independent and functionally redundant targeting signals, each of which contains a subdomain that is required for release from or proper sorting within the endoplasmic reticulum. Certain deletion constructs traffic to multiple locations, including the apicoplast periphery, the rhoptries, and the parasitophorous vacuole, suggesting a common thread for targeting to these specialized compartments.
Lipid Raft Polarization Contributes to Hyphal Growth in
Candida albicans
Authors: Martin Stephen W. , Konopka James B. 
Published: June 2004

ABSTRACT

The polarization of sterol- and sphingolipid-enriched domains (lipid rafts) has been linked to morphogenesis and cell movement in diverse cell types. In the yeast
Saccharomyces cerevisiae
, a dramatic polarization of sterol-rich domains to the shmoo tip was observed in pheromone-induced cells (M. Bagnat and K. Simons, Proc. Natl. Acad. Sci. USA
99:
14183-14188, 2002). We therefore examined whether plasma membrane lipid polarization contributes to the ability of the fungal pathogen
Candida albicans
to grow in a highly polarized manner to form hyphae. Interestingly, staining with filipin revealed that membrane sterols were highly polarized to the leading edge of growth during all stages of hyphal growth. Budding and pseudohyphal cells did not display polarized staining. Filipin staining was also enriched at septation sites in hyphae, where colocalization with septin proteins was observed, suggesting a role for the septins in forming a boundary domain. Actin appeared to play a role in sterol polarization and hyphal morphogenesis in that both were disrupted by low concentrations of latrunculin A that did not prevent budding. Furthermore, blocking either sphingolipid biosynthesis with myriocin or sterol biosynthesis with ketoconazole resulted in a loss of ergosterol polarization and caused abnormal hyphal morphogenesis, suggesting that lipid rafts are involved. Since hyphal growth is required for the full virulence of
C. albicans
, these results suggest that membrane polarization may contribute to the pathogenesis of this organism.
Hph1p and Hph2p, Novel Components of Calcineurin-Mediated Stress Responses in
Saccharomyces cerevisiae
Authors: Heath Victoria L , Shaw Sidney L. , Roy Sharmili , Cyert Martha S. 
Published: June 2004

ABSTRACT

Calcineurin is a Ca
2+
- and calmodulin-dependent protein phosphatase that plays a key role in animal and yeast physiology. In the yeast
Saccharomyces cerevisiae
, calcineurin is required for survival during several environmental stresses, including high concentrations of Na
+
, Li
+
, and Mn
2+
ions and alkaline pH. One role of calcineurin under these conditions is to activate gene expression through its regulation of the Crz1p transcription factor. We have identified Hph1p as a novel substrate of calcineurin.
HPH1
(
YOR324C
) and its homolog
HPH2
(
YAL028W
) encode tail-anchored integral membrane proteins that interact with each other in the yeast two-hybrid assay and colocalize to the endoplasmic reticulum. Hph1p and Hph2p serve redundant roles in promoting growth under conditions of high salinity, alkaline pH, and cell wall stress. Calcineurin modifies the distribution of Hph1p within the endoplasmic reticulum and is required for full Hph1p activity in vivo. Furthermore, calcineurin directly dephosphorylates Hph1p and interacts with it through a sequence motif in Hph1p, PVIAVN. This motif is related to calcineurin docking sites in other substrates, such as NFAT and Crz1p, and is required for regulation of Hph1p by calcineurin. In contrast, Hph2p neither interacts with nor is dephosphorylated by calcineurin. Ca
2+
-induced Crz1p-mediated transcription is unaffected in
hph1
Δ
hph2
Δ mutants, and genetic analyses indicate that
HPH1/HPH2
and
CRZ1
act in distinct pathways downstream of calcineurin. Thus, Hph1p and Hph2p are components of a novel Ca
2+
- and calcineurin-regulated response required to promote growth under conditions of high Na
+
, alkaline pH, and cell wall stress.
Functional Unit of the RNA Polymerase II C-Terminal Domain Lies within Heptapeptide Pairs
Authors: Stiller John W. , Cook Matthew S. 
Published: June 2004

ABSTRACT
Unlike all other RNA polymerases, the largest subunit (RPB1) of eukaryotic DNA-dependent RNA polymerase II (RNAP II) has a C-terminal domain (CTD) comprising tandemly repeated heptapeptides with the consensus sequence Y-S-P-T-S-P-S. The tandem structure, heptad consensus, and most key functions of the CTD are conserved between yeast and mammals. In fact, all metazoans, fungi, and green plants examined to date, as well as the nearest protistan relatives of these multicellular groups, contain a tandemly repeated CTD. In contrast, the RNAP II largest subunits from many other eukaryotic organisms have a highly degenerate C terminus or show no semblance of the CTD whatsoever. The reasons for intense stabilizing selection on CTD structure in certain eukaryotes, and its apparent absence in others, are unknown. Here we demonstrate, through in vivo genetic complementation, that the essential functional unit of the yeast CTD is contained within pairs of heptapeptides. Insertion of a single alanine residue between diheptads has little phenotypic effect, while increasing the distance between diheptads produces a mostly quantitative effect on yeast cell growth. We further explore structural constraints on the CTD within an evolutionary context and propose selective mechanisms that could maintain a global tandem structure across hundreds of millions of years of eukaryotic evolution.
Hemoglobin Regulates Expression of an Activator of Mating-Type Locus α Genes in
Candida albicans
Authors: Pendrak Michael L. , Yan S. Steve , Roberts David D. 
Published: June 2004

ABSTRACT

Phenotypic switching from the white to the opaque phase is a necessary step for mating in the pathogenic fungus
Candida albicans
. Suppressing switching during vascular dissemination of the organism may be advantageous, because opaque cells are more susceptible to host defenses. A repressor of white-opaque switching,
HBR1
(hemoglobin response gene 1), was identified based on its specific induction following growth in the presence of exogenous hemoglobin. Deletion of a single
HBR1
allele allowed opaque phase switching and mating competence, accompanied by a lack of detectable
MTL
α1 and α2 gene expression and enhanced
MTL
a
1
gene expression. Conversely, overexpression of Hbr1p or exposure to hemoglobin increased
MTL
α
gene expression. The
a
1/α2 repressed target gene
CAG1
was derepressed in the same mutant in a hemoglobin-sensitive manner. Regulation of
CAG1
by hemoglobin required an intact
MTL
a
1
gene. Several additional Mtlp targets were perturbed in
HBR1
mutants in a manner consistent with commitment to an
a
mating phenotype, including
YEL007w
,
MF
α,
HST6
, and
RAM2.
Therefore, Hbr1 is part of a host factor-regulated signaling pathway that controls white-opaque switching and mating in the absence of allelic deletion at the
MTL
locus.
Overexpression of Sphingosine-1-Phosphate Lyase or Inhibition of Sphingosine Kinase in
Dictyostelium discoideum
Results in a Selective Increase in Sensitivity to Platinum-Based Chemotherapy Drugs
Authors: Min Junxia , Stegner Andrew L. , Alexander Hannah , Alexander Stephen 
Published: June 2004

ABSTRACT

The efficacy of the chemotherapy drug cisplatin is often limited due to resistance of the tumors to the drug, and increasing the potency of cisplatin without increasing its concentration could prove beneficial. A previously characterized
Dictyostelium discoideum
mutant with increased resistance to cisplatin was defective in the gene encoding sphingosine-1-phosphate (S-1-P) lyase, which catalyzes the breakdown of S-1-P, an important regulatory molecule in cell function and development and in the regulation of cell fate. We hypothesized that the increased resistance to cisplatin was due to an elevation of S-1-P and predicted that lowering levels of S-1-P should increase sensitivity to the drug. We generated three strains that stably overexpress different levels of the S-1-P lyase. The overexpressor strains have reduced growth rate and, confirming the hypothesis, showed an expression-dependent increase in sensitivity to cisplatin. Consistently, treating the cells with
d
-erythro-
N
,
N
,-dimethylsphingosine, a known inhibitor of sphingosine kinase, increased the sensitivity of mutant and parent cells to cisplatin, while addition of exogenous S-1-P or 8-Br-cyclic AMP made the cells more resistant to cisplatin. The increased sensitivity of the overexpressors to cisplatin was also observed with the cisplatin analog carboplatin. In contrast, the response to doxorubicin, 5-flurouracil, or etoposide was unaffected, indicating that the involvement of the sphingolipid metabolic pathway in modulating the response to cisplatin is not part of a global genotoxic stress response. The augmented sensitivity to cisplatin appears to be the result of an intracellular signaling function of S-1-P, because
D. discoideum
does not appear to have endothelial differentiation growth (EDG/S1P) receptors. Overall, the results show that modulation of the sphingolipid pathway at multiple points can result in increased sensitivity to cisplatin and has the potential for increasing the clinical usefulness of this important drug.