bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Screen for Nigericin-Resistant Yeast Mutants Revealed Genes Controlling Mitochondrial Volume and Mitochondrial Cation Homeostasis
Authors: Kucejova Blanka , Kucej Martin , Petrezselyova Silvia , Abelovska Lenka , Tomaska Lubomir 
Published: July 2005

Abstract
Little is known about the regulation of ion transport across the inner mitochondrial membrane in Saccharomyces cerevisiae. To approach this problem, we devised a screening procedure for facilitating the identification of proteins involved in mitochondrial ion homeostasis. Taking advantage of the growth inhibition of yeast cells by electroneutral K+/H+ ionophore nigericin, we screened for genetic mutations that would render cells tolerant to this drug when grown on a nonfermentable carbon source and identified several candidate genes including MDM31, MDM32, NDI1, YMR088C (VBA1), CSR2, RSA1, YLR024C, and YNL136W (EAF7). Direct examination of intact cells by electron microscopy indicated that mutants lacking MDM31 and/or MDM32 genes contain dramatically enlarged, spherical mitochondria and that these morphological abnormalities can be alleviated by nigericin. Mitochondria isolated from the Δmdm31 and Δmdm32 mutants exhibited limited swelling in an isotonic solution of potassium acetate even in the presence of an exogenous K+/H+ antiport. In addition, growth of the mutants was inhibited on ethanol-containing media in the presence of high concentrations of salts (KCl, NaCl, or MgSO4) and their mitochondria exhibited two- (Δmdm31 and Δmdm32) to threefold (Δmdm31Δmdm32) elevation in magnesium content. Taken together, these data indicate that Mdm31p and Mdm32p control mitochondrial morphology through regulation of mitochondrial cation homeostasis and the maintenance of proper matrix osmolarity.
Genome‐wide Examination of the Natural Solar Radiation Response in Shewanella oneidensis MR‐1
Authors: Qiu Xiaoyun , Tiedje James M. , Sundin George W. 
Published: July 2005

ABSTRACTWe previously reported that Shewanella oneidensis MR‐1 is extremely sensitive to natural solar radiation (NSR). Here we analyzed the global transcriptional profile of MR‐1 during a 1‐h recovering period after exposure to ambient solar light at a dose that yields about 20% survival rate on a Luria‐Bertani (LB) plate. We observed the induction of DNA damage‐repair genes, the SOS response as well as detoxification strategies that we previously observed in MR‐1 following artificial UV‐A irradiation. Few prophage‐related genes were induced by natural solar UV radiation, however, in contrast to what was observed following artificial UV‐B irradiation. Overall, the cellular response to NSR in MR‐1 was more similar to that of UV‐A than that of UV‐B, but additional genes involved in detoxification were induced compared with induction by either UV‐B or UV‐A or their sum. Thus, oxidative stress appeared to contribute greatly to the NSR‐induced cytotoxic effects in MR‐1. A total of 29.1% of genome showed differential expression following NSR exposure, which is much greater than following exposure by UV‐B (4.0%), UV‐A (8.2%) or their sum (10.7%). Our data suggest that NSR may impact biological processes in a much more complex manner than previously thought.
Vibrational Spectroscopic Studies on the Disulfide Formation and Secondary Conformational Changes of Captopril–HSA Mixture after UV‐B Irradiation
Authors: Li Mei‐Jane , Lin Shan‐Yang 
Published: July 2005

ABSTRACTThe effects of pH and ultraviolet‐B (UV‐B) irradiation on the secondary structure of human serum albumin (HSA) in the absence or presence of captopril were investigated by an attenuated total reflection (ATR)/Fourier transform infrared (FTIR) spectroscopy. The UV‐B exposure affecting the stability of captopril before and after captopril–HSA interaction was also examined by using confocal Raman microspectroscopy. The results indicate that the transparent pale‐yellow solution for captopril–HSA mixture in all pH buffer solutions, except pH 5.0∼7.0, changed into a viscous form then a gel form with UV‐B exposure time. The secondary structural transformation of HSA in the captopril–HSA mixture with or without UV‐B irradiation was found to shift the maxima amide I peak in IR spectra from 1652 cm−1 assigned to α‐helix structure to 1622 cm−1 because of a β‐sheet structure, which was more evident in pH 3.0, 8.0 or 9.0 buffer solutions. The Raman shift from 1653 cm−1 (α‐helix) to 1670 cm−1 (β‐sheet) also confirmed this result. Captopril dissolved in distilled water with or without UV‐B irradiation was determined to form a captopril disulfide observed from the Raman spectra of 512 cm−1, which was exacerbated by UV‐B irradiation. There was little disulfide formation in the captopril–HSA mixture even with long‐term UV‐B exposure, but captopril might interact with HSA to change the protein secondary structure of HSA whether there was UV‐B irradiation or not. The pH of the buffer solution and captopril–HSA interaction may play more important roles in transforming the secondary structure of HSA from α‐helix to β‐sheet in the corresponding captopril–HSA mixture than UV‐B exposure. The present study also implies that HSA has the capability to protect the instability of captopril in the course of UV‐B irradiation. In addition, a partial unfolding of HSA induced by pH or captopril‐HSA interaction under UV‐B exposure is proposed.
Substituent Effects on the Photophysical Properties of Pterin Derivatives in Acidic and Alkaline Aqueous Solutions
Authors: Cabrerizo Franco M. , Petroselli Gabriela , Lorente Carolina , Capparelli Alberto L. , Thomas Andrés H. , Braun André M. , Oliveros Esther 
Published: July 2005

ABSTRACTPterins are heterocyclic compounds with important biological functions, and most of them may exist in two acid‐base forms in the pH range between 3 and 13 in aqueous solution. In this work, the photophysical properties of acid and basic forms of six compounds of the pterin family (6‐hydroxymethylpterin [HPT], 6‐methylpterin [MPT], 6,7‐dimethylpterin [DPT], rhamnopterin [RPT], N‐methylfolic acid [MFA], and pteroic acid [PA]) have been studied. The effects of the chemical nature of the substituents at position 6 of the pterin moiety and the effects of the pH on the absorption and emission properties are analyzed. The fluorescence characteristics (spectra, quantum yields, lifetimes) of these compounds have been investigated using the single‐photon‐counting technique. Results obtained for pterin derivatives containing small substituents with 1 carbon atom (HPT, MPT, DPT) and short hydrocarbon chain (4 carbon atoms) (RPT) are different from those found for pterin derivatives containing a p‐aminobenzoic acid (PABA) moiety in the substituent (MFA and PA). Fluorescence quantum yields (φF) of the first group of compounds are relatively high (0.4), whereas MFA and PA exhibit very small φF values (0.01).
Mutational Effects on Protein Structural Changes and Interdomain Interactions in the Blue‐light Sensing LOV Protein YtvA
Authors: Losi Aba , Ghiraldelli Elisa , Jansen Sven , Gärtner Wolfgang 
Published: July 2005

ABSTRACTMutagenesis studies on the phototropin‐related protein YtvA from Bacillus subtilis have revealed the role of selected structural elements in interdomain communication. The LOV (light, oxygen, voltage) domain of YtvA undergoes light‐driven reactions similar to that of phot‐LOV, with reversible formation of a covalent flavin‐cysteine adduct. The mutated proteins Ytva‐E105L and YtvA‐E56Q have been studied by UV fluorescence and circular dichroism (CD) spectroscopy. E105 (L in phototropin) is located at the solvent‐exposed surface of the LOV domain central β‐sheet, demonstrated to participate in interdomain interaction in phototropin. CD data show that YtvA‐E105L has a lower α‐helix content in the dark and undergoes larger light‐driven conformational changes than YtvA‐WT. The E56Q mutation breaks the E56‐K97 salt bridge, a structural element highly conserved within the LOV series. In YtvA‐E56Q the CD spectrum is the same as in YtvA‐WT, although the conserved W103 becomes more exposed to the solvent and the dark‐recovery kinetics is slower. These results indicate that the E56‐K97 salt bridge stabilizes locally the protein structure and participates in the regulation of the photocycle but has negligible effects on the overall structure. The E105L mutation, instead, highlights the involvement of the central β‐sheet in the light‐driven conformational changes in LOV proteins.
Transcript Profiling of Periodontal Fibroblasts and Osteoblasts
Authors: Lallier Thomas E. , Spencer Amber , Fowler Melanie M. 
Published: July 2005

Background: Fibroblasts are critical to the establishment and maintenance of the periodontal attachment apparatus (cementum, periodontal ligament [PDL], and bone). In order to characterize the cellular changes that accompany periodontal regeneration, better tools are necessary to distinguish periodontal ligament fibroblasts (PDLF), gingival fibroblasts, and osteoblasts. Our goal is to identify gene markers to better characterize and identify these cell types.Methods: We chose to examine and compare the expression of numerous gene transcripts by semiquantitative reverse transcriptase‐ polymerase chain reaction using primers specific for 44 different gene transcripts in order to better characterize the identity of these cells.Results: Several transcripts were cell‐type specific. Specifically, fibromodulin was expressed only in PDL fibroblasts, while osteopontin was expressed only in dermal fibroblasts. In addition, lumican was expressed by all three types of fibroblasts (PDL, gingival, and dermal), while alkaline phosphatase was expressed by osteoblasts as well as PDL and gingival fibroblasts.Conclusions: Our results indicate that PDL fibroblasts are distinct from either gingival or dermal fibroblasts or osteoblasts. In general, PDL and gingival fibroblasts displayed greater similarity to each other than either displayed toward dermal fibroblasts. Furthermore, both gingival and PDL fibroblasts displayed greater similarity to osteoblasts than to dermal fibroblasts, possibly reflecting their common origin (the neural crest). J Periodontol 2005;76: 1044‐1055.
Evaluation of Surgical and Non‐Surgical Periodontal Therapies, and Immunological Status, of Young Down's Syndrome Patients
Authors: Zaldivar‐Chiapa R.M. , Arce‐Mendoza A.Y. , Rosa‐Ramírez M. De La , Caffesse R.G. , Solis‐Soto J.M. 
Published: July 2005

Background: Individuals with Down's syndrome (DS) differ in their oral condition compared with the healthy population. Periodontal disease in persons with DS under the age of 30 years is very high. Immune deficiencies are also present. For dental practitioners it is difficult to decide on a particular course of treatment. In this study, patients with DS were selected in order to 1) evaluate the effectiveness of surgical and non‐surgical periodontal therapies and 2) assess their immunological status.Methods: The population consisted of 14 DS patients (14 to 30 years old). Surgical and non‐surgical periodontal therapies were compared in a split‐mouth design. Clinical measurements of plaque index (PI), gingival index (GI), probing depth (PD), and clinical attachment levels (CAL) were taken at baseline, posttreatment, 6 months, and 1 year. Immunomodulatory activity of neutrophils was analyzed in vitro by chemotaxis (Boyden migration chamber), phagocytic activity, and production of super‐oxide anion (NBT reduction) tests and compared between DS patients and healthy controls.Results: Both surgical and non‐surgical therapies showed a significant improvement in all the clinical parameters compared to baseline. There were no differences between surgical and nonsurgical therapy in PI or GI. There was a significant PD reduction with the non‐surgical therapy at 1 to 3 mm PD. However in PD >3 mm the surgical therapy, although not statistically significant, showed better results. Neutrophil chemotaxis, phagocytic activity, and production of super‐oxide anion were significantly decreased in the DS patients.Conclusions: After a year, both surgical and non‐surgical therapies have similar periodontal clinical improvement in DS patients. There is partial impairment of immunological functions in DS individuals which does not seem to affect the clinical response to therapy. J Periodontol 2005;76:1061‐1065.
Human Skin and Gingival Keratinocytes Show Differential Regulation of Matrix Metalloproteinases When Combined With Fibroblasts in 3‐Dimensional Cultures
Authors: Chinnathambi Sathivel , Bickenbach Jackie R. 
Published: July 2005

Background: Matrix metalloproteinases (MMP) and their inhibitors are expressed in tissues during interactions between keratinocytes and fibroblasts. Maintaining the balance between MMPs and their inhibitors is critical; failure to do so can lead to severe tissue damage or complete destruction, as seen in periodontal disease. Previously we showed that 3‐dimensional (3‐D) cultures of homotypically‐combined skin and gingival cells mimicked the tissues in protein and lipid production, but heterotypic cultures did not.Methods: We examined the production and activation of MMPs in these homotypic and heterotypic combinations of skin and gingival keratinocytes and fibroblasts during the critical time that they reformed the tissues. Primary fibroblasts and keratinocytes were isolated from normal human gingiva and skin and grown in 3‐D cultures for up to 42 days. MMP‐1, MMP‐2, and MMP‐9 in the media and inhibition of MMPs from these cultures were analyzed.Results: These experiments determined that skin fibroblasts grown with skin or gingival keratinocytes secrete increased amounts of MMP‐1 compared to gingival fibroblasts; that the interaction of keratinocytes with fibroblasts decreases the amount of MMP‐2 produced by the fibroblasts in 3‐D cultures; that skin keratinocytes, but not gingival keratinocytes, interact with fibroblasts to upregulate expression of the active form of MMP‐9; and that medium conditioned by gingival 3‐D cultures does not contain an inhibitor of MMP‐9Conclusion: Varying the type of fibroblast beneath the keratinocytes allowed us to determine that skin and gingival keratinocytes differentially regulate the production and activation of MMP‐9, but not MMP‐2, a finding that could influence the success of tissue grafting after periodontal surgery. J Periodontol 2005;76:1072‐1083.
Analysis of Failed Commercially Pure Titanium Dental Implants: A Scanning Electron Microscopy and Energy‐Dispersive Spectrometer X‐Ray Study
Authors: Shibli Jamil Awad , Marcantonio Elcio , d'Avila Susana , Guastaldi Antonio Carlos , Marcantonio Elcio 
Published: July 2005

Background: The failure of osseointegration in oral rehabilitation has gained importance in current literature and in clinical practice. The integration of titanium dental implants in alveolar bone has been partly ascribed to the biocompatibility of the implant surface oxide layer. The aim of this investigation was to analyze the surface topography and composition of failed titanium dental implants in order to determine possible causes of failure.Methods: Twenty‐one commercially pure titanium (cpTi) implants were retrieved from 16 patients (mean age of 50.33 ± 11.81 years). Fourteen implants were retrieved before loading (early failures), six after loading (late failures), and one because of mandibular canal damage. The failure criterion was lack of osseointegration characterized as dental implant mobility. Two unused implants were used as a control group. All implant surfaces were examined by scanning electron microscopy (SEM) and energy‐dispersive spectrometer x‐ray (EDS) to element analysis. Evaluations were performed on several locations of the same implant.Results: SEM showed that the surface of all retrieved implants consisted of different degrees of organic residues, appearing mainly as dark stains. The surface topography presented as grooves and ridges along the machined surface similar to control group. Overall, foreign elements such as carbon, oxygen, sodium, calcium, silicon, and aluminum were detected in failed implants. The implants from control group presented no macroscopic contamination and clear signs of titanium.Conclusion: These preliminary results do not suggest any material‐related cause for implant failures, although different element composition was assessed between failed implants and control implants. J Periodontol 2005;76:1092‐1099.
Efficacy of Photodynamic Therapy on Inflammatory Signs and Two Selected Periodontopathogenic Species in a Beagle Dog Model
Authors: Sigusch Bernd W. , Pfitzner Anne , Albrecht Volker , Glockmann Eike 
Published: July 2005

Background: Current research aims to find alternatives to conventional methods for suppressing periodontopathogenic bacteria. Photodynamic therapy (PDT) could be a suitable treatment procedure of periodontal infections.Methods: In the present study, the PDT method was tested with two photosensitizers, chlorine e6 and BLC1010, in an experiment on beagle dogs. The animals were infected with Porphyromonas gingivalis (Pg) and Fusobacterium nucleatum (Fn) in all subgingival areas. After infection, we observed clinical signs of gingival inflammation, including an increase of redness and bleeding on probing. Microbiological monitoring before and after treatment was performed using polymerase chain reaction (PCR). PDT was conducted with a diode laser with a wavelength of 662 nm using a power of 0.5 W and the photosensitizers.Results: The PDT procedure carried out with either of the photosensitizers caused a significant reduction in the clinical inflammation signs of redness and BOP, compared to the controls (laser only and no treatment). Furthermore, PDT with chlorine e6 caused a significant reduction in P. gingivalis‐infected sites, whereas there was a lack in suppression after PDT with BLC1010. F. nucleatum could hardly be reduced with chlorine e6, and only to a certain extent with BLC 1010 and laser only. In the control groups, the Pg‐infected test sites did not change.Conclusions: This study demonstrated that the photodynamic therapy using photosensitizer and a 662 nm laser light source is distinctly advantageous in reducing the periodontal signs of redness and bleeding on probing. The procedure also appears to significantly suppress P. gingivalis. J Periodontol 2005;76:1100‐1105.
Bisphosphonate Therapy Improves the Outcome of Conventional Periodontal Treatment: Results of a 12‐Month, Randomized, Placebo‐Controlled Study
Authors: Lane Nancy , Armitage Gary C. , Loomer Peter , Hsieh Susan , Majumdar Sharmila , Wang H.‐Y. , Jeffcoat Marjorie , Munoz Thelma 
Published: July 2005

Background: Bone loss in periodontitis results from inflammatory reactions that stimulate osteoclastic bone resorption. Bisphosphonates inhibit bone resorption and increase bone mass. This study evaluated the effect of bisphosphonate therapy as an adjunct to non‐surgical periodontal treatment in patients with moderate to severe chronic periodontitis.Methods: Patients were randomized (2:1) to one of two bisphosphonate therapies or placebo for 1 year. All patients received non‐surgical periodontal treatment (scaling, root planing) and periodontal maintenance therapy every 3 months. Clinical assessments at baseline and 6 and 12 months included clinical attachment level (CAL), probing depth (PD), and bleeding on probing (BOP). Periodontal bone mass was assessed by dental radiographs at baseline and 12 months using fractal analysis and digital subtraction radiography (DSR).Results: Seventy patients were randomized, 43 to the bisphosphonate group and 27 to the placebo group. Bisphosphonate therapy significantly improved CAL, PD, and BOP relative to the placebo group during the 6‐ to 12‐month period (CAL, P = 0.0002; PD, P = 0.0156; BOP, P = 0.0079). There was no difference in the change in periodontal bone mass between the bisphosphonate and placebo groups as measured by fractal analysis and DSR.Conclusion: These data suggest that bisphosphonate treatment improves the clinical outcome of non‐surgical periodontal therapy and may be an appropriate adjunctive treatment to preserve periodontal bone mass. J Periodontol 2005;76:1113‐1122.
Tetracycline at Subcytotoxic Levels Inhibits Matrix Metalloproteinase‐2 and ‐9 But Does Not Remove the Smear Layer
Authors: Wang Yao , Morlandt Anthony B. , Xu Xiaoping , Carnes David L. , Chen Zhihua , Steffensen Bjorn 
Published: July 2005

Background: The antibacterial and anticollagenolytic properties of tetracycline (TCN) are valuable in periodontal therapy, and TCN treatment can remove the smear layer following root instrumentation. However, recent reports pointing to cytotoxic effects of several acids prompted this study to define TCN concentrations that are anticollagenolytic and remove the smear layer, but have low cytotoxicity.Methods: Human gingival (hGF) and periodontal ligament (hPDL) cells were treated short‐ (3 minutes) or long‐term (24 hours) with TCN to determine concentrations yielding 50% (TD50) and 90% (TD10) cell survival. Activity assays measured TCN concentrations with half‐maximal inhibition (IC50) of matrix metalloproteinase‐ 2 and ‐9 (MMP‐2 and ‐9). Finally, we analyzed the effects of TCN with high (75 mg/ml) or low (1 mg/ml) cytotoxicity on the smear layer by scanning electron microscopy (SEM).Results: The TD50 for TCN after short‐term treatment was 4 mg/ml for both hGF and hPDL. Ninety percent of the cells survived 0.2 mg/ml. With long‐term treatment, the TD50 for hGF and hPDL was 70 and 30 µg/ml, respectively, and the TD10 was 20 and 5 µg/ml. HGF and hPDL recovered from the 3‐minute treatment with 1 mg/ml, but not from concentrations exceeding 3 and 9 mg/ml, respectively. The IC50 was 25 µg/ml for both MMP‐2 and MMP‐9. Whereas 75 mg/ml TCN removed the smear layer, 1 mg/ml TCN had no effects.Conclusions: Tetracycline has significant cytotoxicity on periodontal cells. Since non‐cytotoxic concentrations of TCN inhibited MMP‐2 and ‐9 but had no effects on the smear layer, TCN is not recommended for root surface treatment. J Periodontol 2005;76: 1129‐1139.
Expression of Activated Transcription Factor Nuclear Factor‐κB in Periodontally Diseased Tissues
Authors: Ambili R. , Santhi W.S. , Janam Prasanthila , Nandakumar K. , Pillai M. Radhakrishna 
Published: July 2005

Background: Chronic periodontitis is an inflammatory disease found mainly in adults. Little is known about molecular level changes associated with host response in this condition. Nuclear factor‐κB (NF‐κB) is a transcription factor implicated in immune and inflammatory responses. NF‐κB activation has also been reported to be associated with many chronic inflammatory diseases. The purpose of this paper was to compare the nuclear and cytoplasmic expression of NF‐κB transcription factor (p50/p65) and cytoplasmic expression of IκB in periodontal tissues of periodontitis patients and controls.Methods: Twenty patients with chronic periodontitis and 20 healthy controls were included in the study. Gingival tissues taken during extraction were processed for immunohistochemical staining and evaluation.Results: Nuclear (activated) p50 was found in 90% of periodontal patient tissues compared to only 30% of healthy tissues. A more significant result was obtained with p65 (75% versus 5%). Intense cytoplasmic immunoreactivity was also observed in periodontitis tissues. IκB, the inhibitor of NF‐κB, was expressed only in 5% of periodontally diseased tissues.Conclusion: Activation of NF‐κB (p50/p65) is significant in periodontally diseased tissues, suggesting the potential of inhibitors of NF‐κB in managing periodontitis. J Periodontol 2005;76:1148‐1153.