bluuebunny/crossref_metadata_2025 huggingface dataset:
The up‐regulation of cyclooxygenase‐2 expression in human buccal mucosal fibroblasts by arecoline: a possible role in the pathogenesis of oral submucous fibrosis
Authors: Tsai Chung‐Hung , Chou Ming‐Yung , Chang Yu‐Chao
Published: March 2003

Background:  Aberrant and persistent tissue inflammation are believed to play an important role on the occurrence of tissue fibrosis. Cyclooxygenase (COX)‐2 is an inducible enzyme responsible for prostaglandin synthesis in certain inflammatory diseases. The purpose of this study was to compare COX‐2 expression in normal human buccal mucosa and oral submucous fibrosis (OSF) specimens and further explore the potential mechanism that may lead to induce COX‐2 expression.

Methods:  Fifteen OSF specimens and six normal buccal mucosa were examined by immunohistochemistry. Primary human buccal mucosa fibroblasts (BMFs) were established and challenged with arecoline analyzed by reverse transcriptase polymerase chain reaction. Furthermore, to elucidate whether induction of COX‐2 is associated with cytotoxicity, aspirin (a non‐selective inhibitor of COX enzyme) and NS‐398 (a selective COX‐2 inhibitor), were added to test their protective effects.

Results:  COX‐2 expression was significantly higher in OSF specimens and expressed mainly by epithelial cells, endothelial cells, and cells with fibroblast morphology. In vitro studies indicated that BMFs did not express COX‐2 constitutively. However, when the cells were treated with 80 µg/ml arecoline, COX‐2 expression was up‐regulated as early as half an hour. This indicates that COX‐2 expression is an early cellular response and regulated by arecoline at transcriptional level. In addition, pre‐treatment with glutathione (GSH) precursor, 2‐oxothiazolidine‐4‐carboxylic acid (OTZ), led to a decrease in induction of COX‐2 mRNA by arecoline. GSH synthesis inhibitor, buthionine sulfoximine (BSO), was found to increase arecoline‐induced COX‐2 mRNA levels. Moreover, both of aspirin and NS‐398 at non‐cytotoxic doses are not able to prevent arecoline‐induced cytotoxicity. This indicates that arecoline cytotoxicity is not directly via the induction of COX‐2 expression.

Conclusions:  Taken together, these results suggest that COX‐2 expression is significantly up‐regulated in OSF tissues from areca quid chewers and arecoline may among other constituents be responsible for the enhanced COX‐2 expression in vivo. The regulation of COX‐2 expression induced by arecoline is critically dependent on the cellular GSH concentration.
Candida‐induced stomatopyrosis and its relation to diabetes mellitus
Authors: Vitkov Ljubomir , Weitgasser Raimund , Hannig Matthias , Fuchs Karl , Krautgartner Wolf Dietrich
Published: March 2003

Background:  Glycaemic disorders and oral candidosis can be accompanied by burning mouth sensations. However, no clear relation between all three disorders is known.

Methods:  Seventy‐two native Upper‐Austrians with burning mouth sensations were examined and smears for Candida estimation were taken from the spots where the sensations were felt. All patients with previously unknown diabetes mellitus (DM) were subjected to an oral glucose tolerance test (OGTT). Use of glucocorticoid‐containing anti‐asthmatic sprays and the body mass index (BMI) were determined.

Results:  Of the examined non‐inhalers of sprays, 52% had increased candidal density. A correlation between that increase and type 2 DM was found. The burning sensations in all patients with increased candidal density subsided completely after anti‐mycotic therapy.

Conclusion:  The perception of burning sensations was hypothesised to occur via stimulation of the capsaicin (vanilloid) receptor by Candida metabolites. The Candida‐induced stomatopyrosis should be regarded as a single symptom indicating (predisposition to or established) type 2 DM in non‐inhalers of the concerned population.
Th1 cytokines in oral lichen planus
Authors: Khan Ambereen , Farah Camile S. , Savage Neil W. , Walsh Laurence J. , Harbrow Doug J. , Sugerman Philip B.
Published: March 2003

Background:  Cell‐mediated immune responses in oral lichen planus (OLP) may be regulated by cytokines and their receptors.

Methods:  In situ cytokine expression and in vitro cytokine secretion in OLP were determined by immunohistochemistry and ELISA.

Results:  The majority of subepithelial and intraepithelial mononuclear cells in OLP were CD8+. In some cases, intraepithelial CD8+ cells were adjacent to degenerating keratinocytes. CD4+ cells were observed mainly in the deep lamina propria with occasional CD4+ cells close to basal keratinocytes. Mononuclear cells expressed IFN‐γ in the superficial lamina propria and TNF‐α adjacent to basal keratinocytes. Basal keratinocytes expressed TNF‐α as a continuous band. TNF R1 was expressed by mononuclear cells and basal and suprabasal keratinocytes. There was variable expression of TGF‐β1 in the subepithelial infiltrate while all intraepithelial mononuclear cells were TGF‐β1−. Keratinocytes in OLP stained weakly for TGF‐β1. Unstimulated OLP lesional T cells secreted IFN‐γin vitro. TNF‐α stimulation down‐regulated IFN‐γ secretion and up‐regulated TNF‐α secretion. IL‐4, IL‐10 and TGF‐β1 secretion were not detected.

Conclusions:  These data suggest the development of a T helper 1 immune response that may promote CD8+ cytotoxic T‐cell activity in OLP.
Alterations of nitrate and nitrite content in saliva, serum, and urine in patients with salivary dysfunction
Authors: Xia Dengsheng , Deng Dajun , Wang Songlin
Published: March 2003

Background:  The role of the salivary glands in the maintenance of nitrate and nitrite in saliva is poorly understood. The aim was to study alterations of nitrate and nitrite metabolisms in patients with Sjogren's syndrome (SS) or sialosis.

Methods:  Saliva, serum, and urine samples were collected from healthy volunteers (n = 29), patients with SS (n = 31), and patients with sialosis (n = 30). Concentrations of nitrate and nitrite were determined by high‐performance liquid chromatography (HPLC).

Results:  In the healthy group, the highest concentration of nitrate was found in parotid saliva (172 mg/l), followed by urine (160 mg/l), whole saliva (97 mg/l), and serum (33 mg/l). In the SS group, concentration of nitrate was decreased in parotid saliva and whole saliva, and increased significantly in urine. Concentration of nitrite in whole saliva was significantly decreased in the SS group and increased in the sialosis group.

Conclusion:  Hypofunction of the salivary glands is associated with significant changes of nitrate and nitrite levels in the saliva and urine.
Lichtenberg's Paraclete Fragments
Authors: Katritzky Linde
Published: March 2003

Lichtenberg conceived his Paraclete satire originally against the excessive exuberance of the Sturm und Drang, but gradually his focus shifted, and the work never materialized. As the disconnected, surviving fragments give only vague impressions of his intentions, they have attracted little attention, and have been mostly dismissed as negligible and lacking in merit. Yet the complexities of Lichtenberg's vision emerge when his scattered sketches are integrated with related remarks in his voluminous notes. Then the enigmatic hints, allusions and incomplete memoranda appear as integral parts of the consistent attitude which Lichtenberg invariably directed towards practical applications in everyday life.

The title, Paraclete, is taken as key to his design. Greek for advocate, comforter, intercessor, it is a synonym for the Holy Ghost, translated by Luther as Spirit of Truth. Lichtenberg secularized this term to convey the ideals of the Enlightenment, against which he gauged the inadequate reality and the intellectual failings and abuses that aroused his disapproval and apprehension. Thus, while his targets changed, this focus remained steady. Interpreted in light of the title, these fragments demonstrate Lichtenberg's consuming concern about the misuse of human potential through disregard of the spirit of the Enlightenment and truth.
Direct Reception of Light by Chromatophores of Lower Vertebrates
Authors: OSHIMA NORIKO
Published: March 2003

Rapid color changes of lower vertebrates are caused by the motile activities of pigment cells (chromatophores) present in the skin tissue. Chromatophore motility is generally regulated by neural and/or by endocrine systems. However, in some cases, light also induces pigment aggregation or dispersion directly, which suggests the existence of visual pigments in chromatophores. In fact, some opsins, including melanopsin, have been identified. This article reviews light‐sensitive chromatophores of lower vertebrates. Photoreceptive molecules (visual pigments) and signal transduction of light via a GTP‐binding protein (G protein) are also discussed.
Membranes of Retinal Pigment Epithelial Cells In Vitro are Damaged in the Phagocytotic Process of the Photoreceptor Outer Segment Discs Peroxidized by Ferrous Ions
Authors: Akeo Kiyoshi , Hiramitsu Tadahisa , Yorifuji Hiroshi , Okisaka Shigekuni
Published: March 2003

The ferrous ions released from haemoglobin and storage‐transferrin ions cause oxidative stress in the eyes. We observed the phagocytotic process of the photoreceptor outer segment discs peroxidized by ferrous ions in the retinal pigment epithelial (RPE) cells in vitro, and investigated how the ferrous ions influenced RPE in vitro and the photoreceptor outer segment discs. We obtained isolated photoreceptor outer segment discs using sucrose gradient of specific gravity after homogenizing porcine retinas. After bovine RPE cells were cultured with isolated photoreceptor outer segment discs containing FeCl2 for 5 and 24 h, we incubated the specimens with rhodamine phalloidin, antimouse α‐tubulin antibody and antimouse Ig G (FITC and rhodamine labelled). We observed the specimens by a laser scanning microscopy, and made the ultrathin sections with or without 2% uranyl acetate and 2% lead acetate for examination by transmission electron microscopy. Actin filaments and microtubules of specialized cells such as RPE cells were actively involved in phagocytosis of the photoreceptor outer segment discs. Microtubules were damaged during the phagocytotic process of the photoreceptor outer segment discs peroxidized by ferrous ions. The peroxidation increased the granular and aggregated autofluorescence of the photoreceptor outer segment discs. The membranes of the disc and the phagosomes, and lysosomes in RPE cells were damaged by ferrous ions and had fine particles with high electron density staining without uranium acetate and lead citrate. The cytoskeletons such as actin filaments and microtubules, and the membranes of the phagosomes and the lysosomes in RPE cells in vitro were damaged during the phagocytotic process of the photoreceptor outer segment discs peroxidized by ferrous ions.
Melanocytes are Potential Immunocompetent Cells: Evidence from Recognition of Immunological Characteristics of Cultured Human Melanocytes
Authors: Lu Yan , Zhu Wen‐Yuan , Tan Cheng , Yu Ge‐Hua , Gu Jing‐Xiong
Published: March 2003

The dendritic nature, the strategic location, and other accumulated evidence about the immunologic characteristics of melanocytes suggest that they are not only professional melanin producing cells but are also immunocompetent cells. In this study, we demonstrated that cultured melanocytes express low levels of some immunologically important surface markers such as intercellular adhesion molecule‐1 and CD40. Moreover, we report for the first time CD40 expression by melanocytes can be up‐regulated by interferon‐γ (IFN‐γ) stimulation. Optimal enhancement of CD40 expression was observed at an IFN‐γ concentration of 300 U/ml after a co‐culture period of 72 h. Maximal melanocyte‐driven T lymphocyte proliferation and interleukin‐12 secretion were also observed following the same treatment and proved to be CD40‐dependent. Our data further suggest that upon CD40 ligation, melanocytes up‐regulate their co‐stimulating and adhesion molecules. In addition to previous descriptions about the melanocyte's antigen processing and presenting capacity, we therefore hypothesize a dynamic model in which melanocytes alternatively work as heterogeneous antigen presenting cells. As a result of CD40 expression on the cell surface, melanocytes might contact and subsequently stimulate CD8+ cytotoxic T lymphocytes directly via CD40–CD40L interaction in some cases.
The dentogingival epithelial surface area revisited
Authors: Hujoel P. P. , White B. A. , García R. I. , Listgarten M. A.
Published: March 2003

Recent studies implicating periodontitis as a cause of systemic diseases have reported that the surface area of periodontal pockets exposed to bacterial biofilm ranges from 50 cm2 to 200 cm2. Since the root surface area of the typical human dentition (excluding 3rd molars) is 75 cm2, these estimates appear too large. The goal of this study was to relate linear periodontal probing measurements to the dentogingival surface area (DGES). The DGES comprises both the sulcular and junctional epithelium, present in health, as well as any intervening pocket epithelium present in periodontitis. Formulas to estimate the DGES from clinical measures were derived from a meta‐analysis of root surface areas, published values of root length, and a study that related the percent remaining root surface area to the percent remaining root length. These formulas were applied to a survey of the adult US population, the Veterans Affairs (VA) Dental Longitudinal Study, and a population of individuals visiting a periodontist. Individuals without periodontitis had a typical DGES of 5 cm2. Among individuals with periodontitis, the mean DGES in the three samples ranged from 8 cm2(ranging from 1 cm2 to 29 cm2) to 20 cm2(ranging from 2 cm2 to 44 cm2). It was concluded that the mean DGES among individuals with periodontitis ranges from 8 cm2 to 20 cm2, considerably smaller than the range of 50 cm2 to 200 cm2 currently assumed.
Morphometric evaluation of gingival overgrowth and regression caused by cyclosporin in rats
Authors: Spolidório L. C. , Merzel J. , Villalba H. , Vargas P. A. , Coletta R. D. , Almeida O. P.
Published: March 2003

Cyclosporin A is a selective immunosuppressant, used in organ transplants to prevent graft rejection. Cyclosporin A can cause various side effects including gingival overgrowth. The aim of this work was to evaluate gingival overgrowth of rats treated daily with 10 mg/kg body weight of cyclosporin A for 60 days, as well as the regression after the interruption of treatment. All rats treated with cyclosporin A developed gingival overgrowth, with increased thickness of the epithelium, height and width of the connective tissue. The density of fibroblasts and collagen fibers also increased. Five to 90 days after the interruption of treatment with cyclosporin A, there was a progressive reduction of the gingival volume and of collagen fibers and fibroblast densities. The reduction was more pronounced in the initial periods and after 90 days did not return to the normal values.
Gingipains in the culture supernatant of Porphyromonas gingivalis cleave CD4 and CD8 on human T cells
Authors: Kitamura Y. , Yoneda M. , Imamura T. , Matono S. , Aida Y. , Hirofuji T. , Maeda K.
Published: March 2003

Porphyromonas gingivalis has been shown to attack host defense systems through proteolytic cleavage of a wide variety of members of the systems. In this study, we examined the ability of P. gingivalis culture supernatant to alter the expression of human T cell surface proteins. As judged by flow cytometric analysis, detection of CD4 expression was completely eliminated by the supernatant, but CD8 was less sensitive. When the culture supernatant was added with reducing agents, proteolytic activity was enhanced, resulting in the cleavage of CD8. Mitogenic response of T cells to phytohemagglutinin or concanavalin A was decreased by the treatment of the cells with the culture supernatant of P. gingivalis. The three forms of gingipains (high molecular mass arginine‐specific gingipain, arginine‐specific gingipain 2 and lysine‐specific gingipain) purified from the culture supernatant of P. gingivalis actively cleaved CD4 and CD8 on human T cells, indicating that proteolytic activity of the culture supernatant was due to gingipains. These results suggest that cysteine proteinases like gingipains released from P. gingivalis cleave T cell surface proteins and impede T cell function.
Quantitative comparison of the cytocidal effect of seven macrolide antibiotics on human periodontal ligament fibroblasts
Authors: Maizumi Noriko , Tamura Yukiko , Kanai Hideaki , Tsutsui Takeki
Published: March 2003

The cytocidal effect of seven macrolide antibiotics on human periodontal ligament fibroblasts (Pel cells) was studied. Pel cells were exposed for 48 h to erythromycin (EM), clarithromycin (CAM), roxithromycin (RXM), azithromycin (AZM), josamycin (JM), midecamycin (MDM), and rokitamycin (RKM), and allowed to form colonies. The cytocidal effect of the macrolides was measured as a decrease in colony‐forming efficiency and was found to increase with the concentration. To obtain a quantitative measure of the cytocidal effect, the LD50, i.e. the concentration that decreases colony‐forming efficiency 50% relative to control cells, was extrapolated from the concentration‐response curves. The rank of the macrolides according to their cytocidal effect (LD50) was RKM > RXM > CAM > AZM > JM > MDM ≈ EM. RKM, RXM, CAM, AZM, and JM were at least 1.7–12.2 times more cytocidal than MDM or EM. When extrapolated from the concentration‐response curves, the relative survival of the Pel cells exposed to each of the macrolides at the MIC90 concentrations for periodontopathic bacteria was estimated to be: ≥ 53.8% for RKM, ≥ 92.7% for RXM, ≥ 94.6% for CAM, ≥ 97.1% for AZM, and ≥ 86.2% for EM. The effect of the antibiotics on the mRNA expression of alkaline phosphatase (ALP) and type I procollagen (COL) was examined in Pel cells exposed for 48 h to RXM, CAM, AZM, and EM, which exhibited strong, moderate, and weak cytocidal activity. The constitutive levels of both ALP and COL mRNA were retained in cells exposed to RXM at ≤3 μM, CAM at ≤10 μM, and AZM or EM at ≤3 μM. The MIC90 against periodontopathic bacteria is ≤4.8 μM for RXM, 5.3 μM for CAM, 2.7 μM for AZM, and 21.8 μM for EM. These results suggest that topical administration of CAM or AZM to the gingival crevice at their MIC90 concentration for periodontopathic bacteria would have little adverse effect on the growth and differentiation of the periodontal ligament. It is important to note, however, that these findings have yet to be extrapolated to in vivo conditions.
Enteric Nerves and Diarrhoea
Authors: Lundgren Ove
Published: March 2003

Abstract: This review article discusses the importance of the enteric nervous system for the fluid and electrolyte secretion evoked by luminal secretagogues in the small intestine. The first part of the review summarizes observations on augmented secretion caused by cholera toxin, which has been the subject of extensive studies in the past. The latter part reviews studies of the participation of the enteric nervous system in other secretory states of the gut. The involvement of the enteric nervous system in the pathophysiology of intestinal secretory states opens up potential new sites of actions for drugs in the treatment of diarrhoea. This is discussed in the final part of this review.
In vitro Metabolism of Two Heterocyclic Amines, 2‐Amino‐9H‐pyrido[2,3‐b]indole (AαC) and 2‐Amino‐3‐methyl‐9H‐pyrido[2,3‐b]indole (MeAαC) in Human and Rat Hepatic Microsomes
Authors: Frederiksen Hanne , Frandsen Henrik
Published: March 2003

Abstract: 2‐Amino‐9H‐pyrido[2,3‐b]indole (AαC) and 2‐amino‐3‐methyl‐9H‐pyrido[2,3‐b]indole (MeAαC) are two mutagenic and carcinogenic heterocyclic amines formed during ordinary cooking. In this study, we have investigated the in vitro metabolism of tritium‐labelled AαC and MeAαC in hepatic microsomes from human pools, rats induced with polychlorinated biphenyl (PCB) (Aroclor 1254) and control rats. The microsomes were incubated with AαC and MeAαC and the detoxified and activated metabolites of AαC and MeAαC were separated and characterised by HPLC‐MS. AαC is metabolised to two major and three minor detoxified metabolites, while MeAαC is metabolised to three major and one minor detoxified metabolites. Some AαC and MeAαC are activated by oxidation to the reactive metabolites N2‐OH‐AαC and N2‐OH‐MeAαC, respectively. These reactive N2‐OH‐metabolites react partially in the incubation system with formation of protein adducts, dimers and the parent compound by reduction of the N2‐OH‐metabolites. The distribution between the detoxified and activated metabolites in the different types of hepatic microsomes showed same pattern for both AαC and MeAαC. In PCB‐induced rat microsomes, the major part of the metabolites are detoxified, only a little amount is activated. In control rat microsomes there is a fifty‐fifty distribution between detoxification and activation, while the major part of the metabolites from the human microsomes are activated and reacts to form dimers and protein adducts. These data show that, in human hepatic microsomes compared to rat hepatic microsomes, a major part of AαC and MeAαC are metabolically activated to the reactive N2‐OH‐AαC and N2‐OH‐MeAαC.
Tolterodine and its Active 5‐Hydroxymethyl Metabolite: Pure Muscarinic Receptor Antagonists
Authors: Nilvebrant Lisbeth
Published: March 2003

Abstract:Tolterodine and its major active 5‐hydroxymethyl metabolite (5‐HM) are potent muscarinic receptor antagonists that show selectivity for the urinary bladder over salivary glands in vivo. This tissue selectivity cannot be attributed to muscarinic receptor subtype selectivity, since both compounds are non‐selective with respect to the M1–M5 receptor subtypes. The aim of the present in vitro study was to determine the specificity of tolterodine and 5‐HM for muscarinic receptors compared to other potential cellular targets. Carbachol‐induced contractions of isolated guinea pig bladder were effectively inhibited by tolterodine (IC50 14 nM) and 5‐HM (IC50 5.7 nM). Tolterodine and 5‐HM were weak inhibitors of effects mediated by α‐adrenergic receptors (rat portal vein), histamine receptors (guinea pig ileum) and calcium channels (guinea pig potassium‐depolarised urinary bladder, spontaneously beating right atria and electrically‐driven right papillary muscle). The IC50 values were in the μM range and the antimuscarinic potency of tolterodine was 27, 200 and 370–485 times higher, respectively, than its potency in blocking histamine receptors, α‐adrenoceptors and calcium channels. The active metabolite, 5‐HM, was >900 times less potent at these sites than at bladder muscarinic receptors. Radioligand binding data on 54 different receptors and binding sites showed that tolterodine and 5‐HM bind with significant affinity only at muscarinic receptors. In conclusion, the results of the present study indicate that both tolterodine and 5‐HM are specific muscarinic receptor antagonists. The tissue selectivity of these agents in vivo cannot therefore be explained by secondary pharmacological actions.
Transport of Peptidomimetic Drugs by the Intestinal Di/tri‐peptide Transporter, PepT1
Authors: Brodin Birger , Nielsen Carsten Uhd , Steffansen Bente , Frøkjær Sven
Published: March 2003

Abstract: The apical membrane of small intestinal enterocytes possess an uptake system for di‐ and tripeptides. The physiological function of the system is to transport small peptides resulting from digestion of dietary protein. Moreover, due to the broad substrate specificity of the system, it is also capable of transporting a number of orally administered peptidomimetic drugs. Absorbed peptides may be hydrolysed in the cells due to the high peptidase activity present in the cytosol. Peptidomimetic drugs may, if resistant to the cellular enzyme activity, pass the basolateral membrane via a basolateral peptide transport mechanism and enter the systemic circulation. As the number of new peptide and peptidomimetic drugs are rapidly increasing, the peptide transport system has gained increasing attention as a possible drug delivery system for small peptides and peptide‐like compounds. In this paper we give an updated introduction to the transport system and discuss the substrate characteristics of the di/tri‐peptide transporter system with special emphasis on chemically modified substrates and prodrugs.
Tamoxifen Induces Changes in the Lipid Composition of the Retinal Pigment Epithelium Cell Line D407
Authors: Engelke Maria , Tykhonova Svitlana , Zorn‐Kruppa Michaela , Diehl Horst
Published: March 2003

Abstract:Tamoxifen, the antioestrogenic drug prescribed for long‐term, low‐dose therapy of breast cancer, induces retinopathy. This study evaluates the effects of tamoxifen on the human retinal pigment epithelial cell line D407, attempting to identify the underlying mechanisms on tamoxifen‐induced retinopathy and the involvement of cellular membranes in the cytotoxic action mechanism. We demonstrate that the tamoxifen‐induced decrease in the cell growth of the D407 cell line results from pyknosis and cell cycle arrest rather than from necrosis. Furthermore, D407 cells influence the lipid composition of both plasma membrane and intracellular membranes in response to tamoxifen. Tamoxifen increases the physical order of the lipid bilayer. We observed a compensatory decrease in the cholesterol content of the plasma membrane which results in an increase of the plasma membrane fluidity. In intracellular membranes the phosphatidylcholine content is reduced to 50% of the controls. This reduction may be related to the formation of a second messenger via phospholipase pathway and sustained activation of protein kinase C. Since increased plasma membrane fluidity as well as sustained activation of protein kinase C influence the rod outer segments binding and/or ingestion by retinal pigment epithelial cells, our results suggest that membrane‐mediated pathways contribute to the tamoxifen‐induced retinopathy.
Diacerhein and Rhein Prevent Interleukin‐1β‐Induced Nuclear Factor‐κB Activation by Inhibiting the Degradation of Inhibitor κB‐α
Authors: Mendes Alexandrina Ferreira , Caramona Maria Margarida , De Carvalho Arsélio Pato , Lopes Maria Celeste
Published: March 2003

Abstract: Diacerhein and rhein are anthraquinone compounds that ameliorate the course of osteoarthritis. Recent reports also suggest that these compounds may have antiinflammatory properties, but the cellular mechanisms by which they exert antiosteoarthritic and possibly antiinflammatory effects are still incompletely understood. The purpose of this study was to investigate the ability of diacerhein and rhein to inhibit the activation of the transcription factor nuclear factor‐κB, induced by the proinflammatory cytokine interleukin‐1β, in primary monolayer cultures of bovine articular chondrocytes. We also studied the ability of diacerhein and rhein to prevent the expression of the inducible nitric oxide synthase gene, which is driven by nuclear factor‐κB. We observed that interleukin‐1β induced the degradation of the inhibitor κB‐α protein and the translocation of the protein p65 (a member of the nuclear factor‐κB family) to the nucleus, which were inhibited by diacerhein and rhein, in a dose‐dependent manner. Interleukin‐1β‐induced nuclear factor‐κB binding to a specific (γ‐32P)‐labelled oligonucleotide probe was also inhibited by treatment of chondrocytes with diacerhein or rhein, as revealed by electrophoretic mobility shift assay. Inducible nitric oxide synthase mRNA and protein synthesis and nitric oxide production were also inhibited by diacerhein and rhein, in a dose‐dependent manner. The half‐maximal inhibitory concentrations of diacerhein and rhein, relative to nitric oxide production, were 8.2 μM and 7.7 μM, respectively. These results suggest that diacerhein and rhein inhibit nuclear factor‐κB activation and, consequently, the expression of nuclear factor‐κB‐dependent genes, such as the inducible nitric oxide synthase gene, which can explain their antiosteoarthritic and antiinflammatory effects.
Adjuvant Effect of di‐n‐Butyl‐, di‐n‐Octyl‐, di‐iso‐Nonyl‐ and di‐iso‐Decyl Phthalate in a Subcutaneous Injection Model Using BALB/c Mice
Authors: Larsen Søren T. , Lund Rikke M. , Nielsen Gunnar D. , Thygesen Peter , Poulsen Otto M.
Published: March 2003

Abstract: During the last decades, the prevalence of the allergic airway diseases, asthma and rhinitis, has increased worldwide. Introduction of environmental chemicals with adjuvant effect may play a role in this increase. In the present study, the adjuvant effects of di‐n‐butyl‐, di‐n‐octyl‐, di‐iso‐nonyl‐ and di‐iso‐decyl phthalate are studied in a screening model. Ovalbumin, used as the model antigen, was injected subcutaneously in the neck region of BALB/cJ mice with the selected phthalate in concentrations from 2–2000 μg/ml. Additionally, the mice were boosted once or twice with ovalbumin alone. Immunization with ovalbumin alone, the ovalbumin control group, served as the baseline for antibody production, whereas aluminium hydroxide served as the positive control. The levels of ovalbumin‐specific IgE, IgG1 and IgG2a antibodies in sera were determined. Adjuvant effect was accepted to be present if a statistical increase in antibody production occurred in a test group as compared to an ovalbumin control group together with the fulfillment of dose‐response relationships. Adjuvant effect varied strongly between the phthalates investigated. Phthalates with 8 or 9 carbon atoms in the alkyl side chains were the stronger adjuvants whereas phthalates with shorter or longer alkyl side chains possessed less adjuvant activity. Adjuvant effects were apparent either from the IgE or the IgG1 response or both, whereas no effect was seen on the IgG2a response. Additional studies with airborne exposure are required to establish whether the hazards also result in a significant risk for the development of allergy in man.
Gastric Phenotypic Abnormality in Cholecystokinin 2 Receptor Null Mice
Authors: Chen Duan , Zhao Chun‐Mei , Håkanson Rolf , Rehfeld Jens F.
Published: March 2003

Abstract: Gastrin, released from antral G‐cells, plays an important role in the regulation of gastric acid secretion and is trophic for the stomach. The cholecystokinin type 2 (CCK)2 receptor (previously referred to as CCK‐B/gastrin receptors) is expressed in both parietal cells and ECL cells in the oxyntic mucosa of stomach. Gastric phenotypic abnormality has been observed in CCK2 receptor null (gene knock‐out) mice. Such mice displayed markedly impaired gastric acid secretion, atrophy of the oxyntic mucosa and hypergastrinaemia. The impaired acid secretion may be the result of a reduced parietal cell mass, a reduced proportion of actively secreting parietal cells (with secretory canaliculi), and a replacement of ECL cells by histamine‐free ECL‐like cells. The ECL‐like cells, observed in the CCK2 receptor null mice, lacked the hallmark features of wild‐type ECL cells, i.e. histamine and cytoplasmic secretory vesicles. However, they had the features of endocrine cells, such as the content of pancreastatin (a fragment of chromogranin A), with cytoplasmic small dense‐core granules and microvesicles. We propose that the replacement of ECL cells by ECL‐like cells in the mutant mice reflects an altered differentiation of the same precursors that develop into ECL cells in wild‐type mice. Thus, studies of CCK2 receptor null mice demonstrate the importance of the receptor in the regulation of gastric acid secretion and in the differentiation of ECL cells in the oxyntic mucosa of stomach.
Extended extracorporeal photochemotherapy with extracorporeal administration of 8‐methoxypsoralen in systemic sclerosis. An Austrian single‐center study
Authors: Muellegger R. R. , Hofer A. , Salmhofer W. , Soyer H. P. , Kerl H. , Wolf P.
Published: March 2003

Background: Extracorporeal photochemotherapy (EXP) is an immunomodulating therapy that has been used in a limited number of patients with systemic sclerosis (SSC) with controversial results. The present study was performed to evaluate the efficacy and safety of extended EXP with extracorporeal application of liquid 8‐methoxypsoralen (8‐MOP) in the treatment of SSC. Methods: Eleven women with progressive SSC of recent onset were treated for a period of 16–57 months. Skin changes, physical performance, extracutaneous manifestations, and quality of life were evaluated before initiation of EXP and at regular intervals thereafter. Results: From the start to the last set of EXP, we observed an overall improvement and/or stabilization of skin changes and physical performance in 5 of 11 patients (45%). Extracutaneous manifestations deteriorated in 10 of 11 patients (91%) (P<0.05), and quality of life deteriorated in 9 of 11 patients (82%) from a mean score of 10 before, to 17 at the last set of EXP (P<0.05). No major side effects were noted. Conclusion: Extended EXP with extracorporeal administration of 8‐MOP is a safe and well tolerated treatment modality. However, it provides only (minor) improvement of skin changes of a subset of SSC patients and does not beneficially influence extracutaneous manifestations and quality of life.
Evaluation of the inhibitory activity of topical indomethacin, betamethasone valerate and emollients on UVL‐induced inflammation by means of non‐invasive measurements of the skin elasticity
Authors: Dobrev Hristo
Published: March 2003

Background/Aim: Topical indomethacin has been reported to inhibit ultraviolet light‐induced erythema. The objective of this study was to verify this assertion and to compare indomethacin 10% ointment to betamethasone valerate 0.1% ointment, water‐in‐oil emulsion and oil‐in‐water emulsion by means of non‐invasive skin elasticity measurements.

Methods: Products were applied on the back skin 60 min and 5 min before and 5 min after UVL irradiation. Untreated test sites served as controls. Clinical evaluation, measurements of epidermal hydration (Corneometer) and mechanical properties of the skin (Cutometer) were made 1 h before and 24 h after exposure.

Results: Test areas treated with indomethacin 60 min and 5 min before irradiation showed the significantly lowest visual erythema scores and no significant changes in skin mechanical parameters. At all other test sites, a significant decrease in elasticity parameters (Ue, Ur, Ua/Uf, Ur/Uf) and an increase in viscoelasticity parameters (Uv, Uv/Ue) of the skin were observed. No significant changes of epidermal hydration were found at any of the test sites.

Conclusion: The inhibitory action of topical indomethacin on UVL‐induced inflammation is superior to betamethasone valerate and emollients. Non‐invasive measurement of skin elasticity could be used as a supplementary tool for objective evaluation and comparison of the photoprotective activity of different topical agents.
Sunscreen use and melanoma:a case of evidence‐based prevention?
Authors: Gefeller O. , Pfahlberg A.
Published: March 2003

Background:
A preventive effect of sunscreens on melanoma development is still subject of intense discussion. The practical consequences for changes in public health campaigns are neglected in this debate.

Methods:
An extensive literature search for studies on the association between sunscreen use and melanoma occurrence was performed. The principles of evidence‐based medicine (EBM) are applied to the issue to derive at recommendations for an evidence‐based prevention of melanoma.

Results: We identified 17 case‐control studies providing risk estimates for the relationship under study. These risk estimates are too heterogeneous to allow a reasonable conclusion by summarizing the evidence. The application of the EBM approach yields therefore an inconclusive result: the melanoma protective potential of sunscreens cannot be proven using the existing evidence. The information necessary to fully assess the effect of sunscreen use on melanoma development is not currently available.

Conclusion: Based on the current evidence the focus of recommendations for melanoma prevention in public awareness campaigns has to be changed. It should be much more emphasized to minimize exposure to ultraviolet (UV) radiation during peak hours, wear protective clothing, hats and UV‐opaque sunglasses, seek shade and protect infants and children against too much UV radiation exposure at all than to use sunscreens.
UV‐induced skin changes due to regular use of commercial sunbeds
Authors: Ruegemer J. , Schuetz B. , Hermann K. , Hein R. , Ring J. , Abeck D.
Published: March 2003

Background/aim: Increased pigmentation and thickening of the epidermis are the most important photoprotective skin reactions induced by ultraviolet (UV) radiation. The present study was designed to find out what changes are induced by regular use of commercial sunbeds twice weekly over a period of 6 weeks.

Methods:
The parameters analysed were skin pigmentation measured by chromametry, minimal erythema dose (MED) as a parameter of light sensitivity, epidermal thickening as determined by histology, induction of keratinocyte apoptosis as determined by TUNEL staining and antioxidant metabolism as measured by changes of cis‐ and trans‐urocanic acid (UCA) content of the skin.

Results: As expected, chromametry confirmed the clinically obvious increased skin pigmentation. However, no increase in MED was observed. In addition, neither epidermal thickening nor sunburn cells were seen. Significant detectable changes in proportion of the UCA isomer content of the UV‐exposed skin were seen. The total UCA and cis‐UCA content increased significantly between nearly all points of measurement. The amount of trans‐UCA first decreased, then increased significantly between the different time points.

Conclusion: Our data indicate that sunbed‐induced tanning is non‐protective, which has to be addressed for persons looking for this effect before planning a stay in a sunny climate. However, sunbed‐induced tanning may influence immunological reactions.
The modulation of neuronal activity by melatonin: In vitro studies on mouse hippocampal slices
Authors: Hogan M.V. , El‐Sherif Y. , Wieraszko A.
Published: March 2003

The influence of melatonin on evoked potentials recorded from the CA1 field of mouse hippocampal slices was investigated. Melatonin (0.1–2.0 mM) and its analog, 6‐chloromelatonin (0.1–0.5 mM) depressed evoked potentials (EPSP and the population spike) in a concentration‐dependent manner. The melatonin‐induced depression was followed by a slow recovery phase. Since the fiber potential was not affected, it was concluded that melatonin influenced synaptic efficiency and/or cell excitability. Luzindole, an antagonist of MT2 melatonin receptors, although slightly depressing evoked potentials when applied by itself (100 μM), blocked any further inhibition by melatonin when added afterwards. We concluded that melatonin reduced synaptic efficiency and/or excitability of hippocampal neurons most likely through interaction with MT2 melatonin receptors, but other possible mechanisms of melatonin action are also considered.
Melatonin protects against streptozotocin, but not interleukin‐1β‐induced damage of rodent pancreatic β‐cells
Authors: Andersson Annika K. , Sandler Stellan
Published: March 2003

In the present study, we examined whether melatonin can protect rodent pancreatic islets against streptozotocin (STZ) and interleukin‐1β (IL‐1β)‐induced suppression of β‐cell function. Formation of free radicals, DNA damage and extensive DNA repair leading to depletion of intracellular nicotinamide adenine dinucleotide (NAD) may mediate STZ toxicity. Activation of inducible nitric oxide synthase and nitric oxide (NO) formation may cause IL‐1β‐induced β‐cell impairment. We also studied the effect of melatonin against STZ‐induced hyperglycemia in C57BL/Ks mice. For in vitro studies, cultured rat islets were exposed to melatonin (100 μM–1 mM) 30 min prior to STZ (0.5 mM) or IL‐1β (25 U/mL) addition. After an additional 30 min incubation with STZ, islet function and NAD content were analyzed either acutely or after 18 hr of recovery in fresh culture medium. For IL‐1β experiments, islets were incubated for 48 hr with the cytokine before evaluation of islet function. We found that melatonin counteracted STZ‐induced inhibition of glucose metabolism and insulin release in cultured rat islets after 18 hr of recovery. Moreover, NAD levels were higher in the melatonin‐treated group at this time point. Melatonin had no effect on IL‐1β‐induced islet inhibition of glucose oxidation or NO formation. Diabetes induced by STZ (140 mg/kg body weight; i.v.) was effectively prevented by administration of melatonin (100 mg/kg body weight; i.p.) 30 min before STZ injection. We conclude that the protective effects of melatonin against β‐cell damage may be related to interference with DNA damage and poly(ADP‐ribose) polymerase (PARP) activation rather than through effects on NO generation pathways.
Melatonin and 6‐OHMS in high‐intensity magnetic fields
Authors: Graham Charles , Cook Mary R. , Gerkovich Mary M. , Sastre Antonio
Published: March 2003

We determined if all‐night exposure to 60 Hz magnetic fields at an intensity well within the upper range of occupational exposures (resultant intensity=127.3 microTesla [μT]) resulted in suppression of melatonin or its major metabolite 6‐hydroxymelatonin‐sulfate (6‐OHMS) in the first‐void morning urine of 24 healthy male volunteers. Measures collected after continuous and intermittent magnetic field exposure test conditions were compared to similar measures collected after an equivalent no‐exposure control condition. Urinary concentrations of melatonin and 6‐OHMS did not differ as a function of type of magnetic field exposure, nor did they differ between field exposure and control conditions. These results demonstrate that the nocturnal secretion and metabolism of melatonin are not altered in humans by field exposure at an intensity over 600 times higher than that typically encountered in the home.
The effect of variations in pH and temperature on stability of melatonin in aqueous solution
Authors: Daya S. , Walker R.B. , Glass B.D. , Anoopkumar‐Dukie S.
Published: March 2003

Melatonin (N‐acetyl‐5‐methoxytryptamine) has a diverse range of functions, including the control of neuroendocrine events. A number of studies have shown that melatonin may be of potential benefit for the treatment of insomnia, as well as neurodegenerative disorders. At present, there are numerous dosage forms of melatonin, with the oral route of administration being most popular. Presently, there is little information on the stability of melatonin over a pH range. With the changes in pH in the gastro‐intestinal tract, as well as in different experimental conditions, information on the stability of melatonin would be important. We used a high‐performance liquid chromatography method to determine the stability of melatonin solutions over a pH range (1.2–12) at room temperature and at 37°C over a period of 21 days. The results show that no melatonin degradation occurred in the first 2 days. From days 3 to 21, there was a gradual decline in melatonin at all pHs, with the decline not exceeding 30%. No decline in melatonin levels occurred in the first 2 days at 37°C. From days 3 to 21, melatonin levels declined gradually, with the decline not exceeding 29%.
Clearance of melatonin and 6‐sulfatoxymelatonin by hemodialysis in patients with end‐stage renal disease
Authors: Lüdemann P. , Zwernemann S. , Lerchl A.
Published: March 2003

Patients with end‐stage renal disease (ESRD) suffer from a number of related disorders. These include endocrine abnormalities, sleep disturbances, and depression. Melatonin is involved in the synchronization of exogenous zeitgebers with the endogenous rhythms, and it has effects on various psychological factors. As the concentrations of melatonin and the effects of dialysis have only occasionally been investigated in ESRD, we performed a study involving 35 patients, measuring the serum concentrations of melatonin, and of its major metabolite 6‐sulfatoxymelatonin (aMT6s), before and after hemodialysis. Serum samples taken during morning hours from a control group (n=11) with intact kidneys served as controls. Patients were dialyzed for approximately 4 hr between 07:00 and 13:00 hr (S1), between 13:00 and 20:00 hr (S2), or between 18:30 and 22:30 hr (S3). Mean melatonin concentrations before hemodialysis were highly elevated when compared with the controls (40.6 vs. 6.7 pg/mL; P<0.001). Although melatonin levels were decreased to 20.3 pg/mL after dialysis, they were still well above the control levels. Likewise, aMT6s concentrations before dialysis were highly elevated in ESRD patients before dialysis when compared with controls (39.5 vs. 2.0 pg/mL; P<0.001), and also decreased by dialysis to levels still well above control levels (25.3 pg/mL). Clearance efficacy was better for melatonin (48.9%) than for aMT6s (36.6%; P<0.05). In ESRD patients, a diurnal rhythm for melatonin was observed (S1, 45.1 pg/mL; S2, 31.5 pg/mL; S3, 48.7 pg/mL; P<0.05), indicating that the normal synthesis rhythm is maintained. None of the following secondary disorders were correlated with melatonin concentrations: insomnia, delayed sleep onset, night‐time arousals, and restless‐leg syndrome. The reason for this observation is probably the melatonin concentrations, which were so high that no sub‐classification could be identified. It is concluded that in ESRD patients, hemodialysis is unable to decrease elevated levels of melatonin and aMT6s to normal values. It is speculated that some of the secondary disorders in ESRD are caused by supraphysiological concentrations of melatonin.
Melatonin suppresses homocysteine enhancement of serotonin‐induced vasoconstriction in the human umbilical artery
Authors: Okatani Y. , Wakatsuki A. , Reiter R.J.
Published: March 2003

Hyperhomocysteinemia is a major and independent risk factor for vascular disease. Oxidative stress is a possible mechanism for homocysteine (Hcy)‐induced endothelial dysfunction. Herein, we evaluated the antioxidant property of melatonin as related to the vasospastic effect of Hcy on the human umbilical artery. Helical strips of human umbilical arteries with intact endothelium were obtained at elective Caesarean delivery between 37 and 39 wks of gestation. Changes in 5‐hydroxytryptamine (5‐HT)‐induced vasoconstriction were measured. Arterial strips were treated with FeSO4 (10 μM) and Hcy (10 or 100 μM) or pre‐treated with a hydroxyl radical (·OH) scavenger (mannitol, 20 mM), a cyclooxygenase inhibitor (indomethacin, 20 μM), nitric oxide (NO) synthesis inhibitor (L‐NG‐monomethylarginine, LNMA, 200 μM), or melatonin (1 or 10 μM). Hcy potentiated 5‐HT‐induced constriction in a concentration‐dependent manner. Pre‐treatment with mannitol significantly suppressed the vasospastic effect of Hcy. LNMA augmented the vasospastic effect of Hcy, but indomethacin did not. Melatonin significantly suppressed the vasospastic effect of Hcy in a concentration‐dependent manner. These findings suggest that Hcy potentiates 5‐HT‐induced vasoconstriction in the human umbilical artery, possibly by suppressing bioavailable NO. Melatonin protects against the vasospastic effect of Hcy, most likely by scavenging ·OH arising from Hcy autooxidation.