bluuebunny/crossref_metadata_2025 huggingface dataset:
Muscarinic acetylcholine receptors regulating cell cycle progression are expressed in human gingival keratinocytes
Authors: Arredondo J. , Hall L. L. , Ndoye A. , Chernyavsky A. I. , Jolkovsky D. L. , Grando S. A.
Published: March 2003

We have previously reported the presence in human gingival keratinocytes (GKC) of choline acetyltransferase, the acetylcholine (ACh) synthesizing enzyme, acetylcholinesterase, the ACh degrading enzyme, and α3, α5, α7, β2 as well as α9 nicotinic ACh receptor subunits. To expand the knowledge about the role of ACh in oral biology, we investigated the presence of the muscarinic ACh receptor (mAChR) subtypes in GKC. RT‐PCR demonstrated the presence of m2, m3, m4, and m5 mRNA transcripts. Synthesis of the respective proteins was verified by immunoblotting with the subtype‐specific antibodies that revealed receptor bands at the expected molecular weights. The antibodies mapped mAChR subtypes in the epithelium of human attached gingiva and also visualized them on the cell membrane of cultured GKC. The whole cell radioligand binding assay revealed that GKC have specific binding sites for the muscarinic ligand [3H]quinuclidinyl benzilate, Bmax = 222.9 fmol/106 cells with a Kd of 62.95 pM. The downstream coupling of the mAChRs to regulation of cell cycle progression in GKC was studied using quantitative RT‐PCR and immunoblotting assays. Incubation of GKC for 24 h with 10 µm muscarine increased relative amounts of Ki‐67, PCNA and p53 mRNAs and PCNA, cyclin D1, p21 and p53 proteins. These effects were abolished in the presence of 50 µm atropine. The finding in GKC of mAChRs coupled to regulation of the cell cycle progression demonstrate further the structure/function of the non‐neuronal cholinergic system operating in human oral epithelium. The results obtained in this study help clarify the role for keratinocyte ACh axis in the physiologic control of oral gingival homeostasis.
The influence of membrane exposure on the outcomes of guided tissue regeneration: clinical and microbiological aspects
Authors: Ling Li‐Jane , Hung Shan‐Ling , Lee Ching‐Fang , Chen Yen‐Ting , Wu Kai‐Ming
Published: March 2003

The aim of the present study was to evaluate the influence of membrane exposure on guided tissue regeneration (GTR). Thirty patients with 2‐wall or 3‐wall intraosseous defects were treated with GTR. Periodontal index, gingival index, bleeding on probing, probing depth, clinical attachment level and recession were assessed at the baseline examination, as well as immediately prior to and six months after GTR. The numbers of Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans on the retrieved expanded polytetrafluoroethylene (e‐PTFE) membranes were assessed using polymerase chain reaction. The results showed that 26.3% of the membrane exposure sites had zero attachment gain. The membrane exposure sites tended to achieve a smaller clinical attachment gain and had significantly greater marginal tissue recession ( p = 0.006). In addition, the exposed membranes harbored significantly more A. actinomycetemcomitans than the non‐exposed membranes (p = 0.029). In conclusion, membrane exposure resulted in a poor GTR outcome. The amount of A. actinomycetemcomitans on the exposed membrane may be a major contributing factor to the outcome of GTR.
Enhanced expression of vascular endothelial growth factor by periodontal pathogens in gingival fibroblasts
Authors: Suthin Kanyarat , Matsushita Kenji , Machigashira Miho , Tatsuyama Syouko , Imamura Takahisa , Torii Mitsuo , Izumi Yuichi
Published: March 2003

Vascular endothelial growth factor (VEGF) has recently attracted attention as a potent inducer of vascular permeability and angiogenesis. Aberrant angiogenesis is often associated with lesion formation in chronic periodontitis. The aim of the present study was to investigate the properties of VEGF expression in human gingival fibroblasts (HGF) culture. HGF were stimulated with lipopolysaccharide (LPS), vesicle (Ve) and outer membrane protein (OMP) from Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis. HGF constitutively produced VEGF and levels were significantly enhanced (P < 0.01) by stimulation with Ve and OMP from A. actinomycetemcomitans and P. gingivalis at concentrations of 10 µg/ml or higher. On the other hand, VEGF levels were not increased by LPS stimulation. VEGF mRNA expression was also observed in Ve‐ and OMP‐stimulated HGF. A vascular permeability enhancement (VPE) assay was performed using guinea pigs to ascertain whether supernatant from cultures of Ve‐ and OMP‐stimulated HGF enhance vascular permeability in vivo. Supernatant from cultures of Ve‐ and OMP‐stimulated HGF strongly induced VPE. This was markedly suppressed upon simultaneous injection of anti‐VEGF polyclonal antibodies with the supernatant. Heating and protease treatment of the stimulants reduced the VEGF enhancing levels in Ve and OMP in vitro. These results suggest that Ve and OMP may be crucial heat‐labile and protease‐sensitive components of periodontal pathogens that enhance VEGF expression. In addition, VEGF might be associated with the etiology of periodontitis in its early stages according to neovascularization stimulated by periodontal pathogens causing swelling and edema.
Modulation of Fluoride Toxicity in Rats by Calcium Carbonate and by Withdrawal of Fluoride Exposure
Authors: Ekambaram P. , Paul Vanaja
Published: March 2003

Abstract: In order to assess the effect of calcium on the toxic effects of fluoride, adult female Wistar rats were treated with sodium fluoride (NaF, 500 ppm in drinking water) alone or in combination with calcium carbonate (CaCO3, 50 mg/kg by oral intubation) daily for 60 days. Food, water and fluoride intake were measured daily for 60 days. Body weight gain, exploratory motor activity, rota‐rod motor coordination, dental structure, activities of acetylcholinesterase (AchE, brain and skeletal muscle) and Na+ K+ ATPase (erythrocyte membrane and skeletal muscle) and the concentrations of protein (serum and skeletal muscle), calcium (serum) and fluoride (serum) were determined in these animals 24 hr after the last treatment. The same parameters were tested in another group, 60 days after withdrawal of NaF exposure (500 ppm in drinking water daily for 60 days). NaF treatment decreased food and water intake, reduced body‐weight gain and impaired exploratory motor activity and rota‐rod performance. Dental lesions, inhibition of the activities of AchE and N+ K+ ATPase and a decrease in the concentration of protein, and serum calcium were also observed in these animals. These effects were accompanied by a marked elevation of fluoride concentration in the serum. CaCO3 decreased the concentration of fluoride in the serum of NaF‐treated animals. A decrease in serum fluoride concentration was found also after NaF withdrawal. A prevention of locomotor behavioural, biochemical and dental toxicities of fluoride was observed both in these groups. It is concluded that the dose of CaCO3 used in the present study has a potential to prevent the toxicity of fluoride by maintaining serum fluoride at a less toxic level. Further, the toxic effects of fluoride are reversible if its exposure is withdrawn for 2 months.
Diabetes and Elimination of Antipyrine in Man: An Analysis of 298 Patients Classified by Type of Diabetes, Age, Sex, Duration of Disease and Liver Involvement*
Authors: Sotaniemi Eero A. , Pelkonen Olavi , Arranto Arno J. , Tapanainen Päivi , Rautio Arja , Pasanen Markku
Published: March 2003

Abstract: Effects of diabetes on hepatic drug metabolism in man has not yet been adequately clarified. Two hundred ninety‐eight diabetic patients, classified by type of the disease, age, gender, duration of therapy and liver involvement, were investigated. The antipyrine plasma clearance rate and cytochrome P450 content determinations in liver biopsies of subjects with diagnostic liver biopsy were used as indices of hepatic drug metabolising capacity. Drug metabolism was reduced as a function of age. Antipyrine elimination rate was dependent on the type of diabetes (type 1 versus type 2) and gender. Untreated type 1 patients eliminated antipyrine rapidly and insulin treatment normalised antipyrine elimination (clearance rates 89.5±20.3 versus 58.8±17.2 ml/min.; P<0.001). Males aged 16–59 years, but not over 60, who responded insufficiently to insulin therapy, had a rapid antipyrine elimination, which could be normalised by readjustment of insulin administration. Women with insufficient glucose control on insulin therapy had antipyrine elimination rate comparable to controls. Among type 2 diabetic patients, women metabolised antipyrine normally, but men over 40 years of age showed a reduced antipyrine metabolism. In conclusion: Drug metabolism in diabetes is affected by the type of disease, therapy and its effectiveness, and age and gender of the patients. These factors should be taken into account when evaluating overall drug metabolism in diabetic patients. This is especially important when investigating pharmacokinetics of new drugs for diabetic patients at different phases of the disease.
Intravenously Administered Oxotremorine and Atropine, in Doses Known to Affect Pain Threshold, Affect the Intraspinal Release of Acetylcholine in Rats
Authors: Abelson Klas S. P. , Höglund A. Urban
Published: March 2003

Abstract: Both systemically and intrathecally administered cholinergic agonists produce antinociception while cholinergic antagonists decrease pain threshold. The mechanism and the site of action of these substances are not known. In the present study it was hypothesized that systemically administered muscarinic agonists and antagonists modify nociceptive threshold by affecting intraspinal release of acetylcholine (ACh). Catheters were inserted into the femoral vein in rats maintained on isoflurane anaesthesia for administration of oxotremorine (10–300 μg/kg) and atropine (0.1, 10, 5000 μg/kg). Spinal microdialysis probes were placed intraspinally at approximately the C2–C5 spinal level for sampling of acetylcholine and dialysis delivery of atropine (0.1, 1, 10 nM). Additionally, the tail‐flick behaviour was tested on conscious rats injected intraperitoneally with saline, atropine (10, 100 and 5000 μg/kg), or subcutaneously with oxotremorine (30, 100, 300 μg/kg). Subcutaneous administration of oxotremorine (30, 100, 300 μg/kg) significantly increased the tail‐flick latency. These doses of oxotremorine dose‐dependently increased the intraspinal release of acetylcholine. Intravenously administered atropine, in a dose that produced hyperalgesia (5000 μg/kg) in the tail‐flick test, significantly decreased the intraspinal release of acetylcholine. Our results suggest an association between pain threshold and acetylcholine release in spinal cord. It is also suggested that an approximately 30% increase in basal ACh release produces antinociception and that a 30% decrease in basal release produces hyperalgesia.
Effect of the Anti‐Breast Cancer Drug Tamoxifen on Ca2+ Movement in Human Osteosarcoma Cells
Authors: Lu Yih‐Chau , Jiann Bang‐Ping , Chang Hong‐Tai , Huang Jong‐Khing , Chen Wei‐Chung , Su Warren , Jan Chung‐Ren
Published: March 2003

Abstract:The anti‐breast cancer drug tamoxifen has recently been shown to cause an increase in [Ca2+]i in renal tubular cells, breast cells and bladder cells. Because tamoxifen is known to interact with oestrogens leading to modulation of bone metabolism, the present study was aimed at exploring whether tamoxifen could alter Ca2+ signaling in human osteoblast‐like MG63 cells. Cytosolic free Ca2+ levels were recorded by using the Ca2+‐sensitive dye fura‐2. Tamoxifen induced a sustained [Ca2+]i increase at concentrations above 1 μM with an EC50 of 8 μM. Removal of extracellular Ca2+ reduced the response by 40%, suggesting that tamoxifen induced both Ca2+ influx and store Ca2+ release. Tamoxifen‐induced Ca2+ influx was confirmed as tamoxifen caused Mn2+ influx‐induced quench of fura‐2 fluorescence. In Ca2+‐free medium, pretreatment with 10 μM tamoxifen abolished the [Ca2+]i increase induced by 1 μM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor), and by 2 μM carbonylcyanide m‐chlorophenylhydrazone (a mitochondrial uncoupler). Conversely, pretreatment with thapsigargin and carbonylcyanide m‐chlorophenylhydrazone only reduced 64% of tamoxifen‐induced [Ca2+]i increases. Addition of 2 μM U73122 to inhibit phospholipase C activity abolished the [Ca2+]i increase induced by 1 μM histamine, a phospholipase C‐dependent Ca2+ mobilizer, without affecting 10 μM tamoxifen‐induced Ca2+ release. The [Ca2+]i increase induced by 10 μM tamoxifen was not altered by 10 μM of nifedipine, verapamil and diltiazem. Together, the data show that tamoxifen induced a lasting increase in [Ca2+]i in human osteoblast‐like cells by causing Ca2+ influx and releasing Ca2+ from multiple stores in a phospholipase C‐independent manner.
In Vitro Cytotoxicity of Protocatechuic Acid to Cultured Human Cells from Oral Tissue: Involvement in Oxidative Stress
Authors: Babich Harvey , Sedletcaia Anya , Kenigsberg Bracha
Published: March 2003

Abstract: Data on the biologic activity of protocatechuic acid are contradictory; some studies have shown that it acts as an antioxidant and suppresses chemical‐induced carcinogenesis and others that it induces oxidative stress and promotes tumour formation. The anticarcinogenicity of protocatechuic acid was postulated to be related, in part, to its specific suppression of neoplastic hyperproliferation. To determine whether protocatechuic acid was preferentially antiproliferative to malignant cells, non‐malignant and carcinoma cells were exposed for 24 hr to protocatechuic acid (2.5 to 25 mM) and viability was assessed with the neutral red assay. The cell lines were derived from tissues of the human oral cavity, the initial site of exposure upon ingestion of dietary protocatechuic acid, and included normal GN61 gingival fibroblasts, immortalized, non‐tumorigenic S‐G gingival epithelial cells, and malignant HSG1 cells derived from the salivary gland, HSC‐2 cells from the floor of the oral cavity, and CAL27 cells from the tongue. Selective toxicity of protocatechuic acid to malignant cells was not observed. Furthermore, using a total cellular protein determination to quantitate cell growth, no differences in comparative sensitivities of S‐G epithelial cells and HSG1 carcinoma cells were noted in a 3 day continuous exposure to 2.5 to 12.5 mM protocatechuic acid and in recovery from a 24 hr exposure to 3 to 15 mM protocatechuic acid. The S‐G and HSG1 cells were then used to study the effects of elevated concentrations of protocatechuic acid on oxidative stress. For both cell types, protocatechuic acid induced oxidative stress, presumably through its bioactivation by a tyrosinase pathway. A brief exposure to 25 mM protocatechuic acid lowered the levels of intracellular glutathione and potentiated Fe2+‐induced lipid peroxidation of the cells. As determined with the neutral red assay, S‐G and HSG1 cells exposed briefly to a non‐toxic level (0.5 mM) of the glutathione depleter, 1,3‐bis(2‐chloroethyl)‐N‐nitrosourea, were hypersensitive to a subsequent challenge with 10 mM protocatechuic acid and preexposure of the S‐G and HSG1 cells to a nontoxic level of protocatechuic acid (2.5 mM) enhanced their sensitivity to a subsequent exposure to tert‐butyl hydroperoxide. These findings were consistent with protocatechuic acid, at high levels (≥10 mM), acting as an inducer of oxidative stress.
Is Cytochrome P450 CYP2D Activity Present in Pig Liver?
Authors: Skaanild Mette T. , Friis Christian
Published: March 2003

Abstract: The presence of CYP2D in pig livers has been studied using different strains of pig, different CYP2D test substrates and monoclonal and polyclonal antibodies. The results of the studies lacked consistency, therefore the aim of this study was to identify the reasons for these inconsistencies. Liver microsomes isolated from conventional pigs and minipigs were tested in Western blotting using both monoclonal and polyclonal antibodies against human CYP2D6. The microsomes were also incubated with three different CYP2D test substrates. The immunoblotting only gave a positive response when hybridised with polyclonal antibody. The pig microsomes did not metabolise debrisoquine, but metabolised two other test substrates, dextromethorphan and bufuralol. No correlation was found between the two enzyme assays and CYP2D apoprotein level. On the other hand positive correlations were found between dextromethorphan and bufuralol metabolism and the CYP2B immunochemical protein level, indicating that the CYP2B isoenzyme may be involved in the metabolism of these substrates. Further, assays using immunoinhibition and chemical inhibition of these reactions were performed. No response was obtained in the immunoinhibition assay. When using chemical inhibition, however, an average inhibition percentage of 83 were obtained with orphenadrine, a human CYP2B inhibitor. Average Ki values of 26.9 μM and 43.6 μM for orphenadrine indicate that it was a potent inhibitor. A rat and a mouse CYP2B inhibitor, resveratrol and pilocarpine, inhibited the reaction with an average of 40 and 70 percentage respectively. Orphenadrine did not inhibit CYP1A, CYP2A, CYP2E and CYP3A activities up to more than maximum 12 percentage, showing that it was almost selective for dextromethorphan metabolism. These results indicate that dextromethorphan and bufuralol metabolism may be catalysed by CYP2B and not CYP2D.
A full‐UV spectrum absorbing daily use cream protects human skin against biological changes occurring in photoaging
Authors: Seité S. , Colige A. , Piquemal‐Vivenot P. , Montastier C. , Fourtanier A. , Lapière C. , Nusgens B.
Published: March 2003

Background: There is overwhelming evidence that exposure of human skin to ultraviolet radiations (UVR) leads to the development of cutaneous photoaging and eventually to neoplasia. This study was designed to evaluate in humans the protection afforded by a daily use cream containing a photostable combination of UVB and UVA absorbers (Uvinul® N539, Parsol® 1789 and Mexoryl® SX) providing a continuous absorption through the entire UV spectrum, against damages induced by repeated daily exposure to solar simulated radiation (SSR).

Methods: Buttock skin of 12 healthy volunteers was exposed 5 days per week for 6 weeks to one minimal erythema dose of solar simulated radiation per exposure. The following parameters in treated and untreated skin were evaluated: erythema, pigmentation, skin hydration, skin microtopography, histology and immunochemistry, and collagen and metalloproteinase (MMP) mRNA levels.

Results: In SSR exposed unprotected skin sites, we observed melanization and changes in the skin hydration and microtopography. The epidermis revealed a significant increase in stratum corneum and stratum granulosum thickness. In the dermis, an enhanced expression of tenascin and a reduced expression of type I pro‐collagen were evidenced just below the dermal epidermal junction. Although we were unable to visualize any change in elastic fibers in exposed buttock skin, a slightly increased deposition of lysozyme and alpha 1 antitrypsin on these fibers was observed using immunofluorescence techniques. Furthermore, types I and III collagen mRNA were slightly increased and a significant enhancement (up to 2.8‐fold) of MMP‐2 mRNA level was observed. The daily use cream was shown to prevent all these biological changes.

Conclusion: Our results show in vivo that an appropriate full‐UV spectrum product significantly reduces the solar‐UV‐induced skin damage, demonstrating the benefit of daily photoprotection.
Interaction of commonly used emollients with photochemotherapy
Authors: Boyvat Ayşe , Erdi Hatice , Birol Ahu , Gůrgey Erbak
Published: March 2003

Background/Aim: Even though emollients are commonly used in combination with photochemotherapy, we still lack guidance for the selection of the appropriate emollient to be used in combination with photochemotherapy. The purpose of our study was to determine the interaction of commonly used emollients with photochemotherapy.

Methods: The study was carried on 75 healthy volunteers. In order to assess the effects of five different emollients – white petrolatum, 3% salicylic acid in white petrolatum, Balmandol, Decubal and Urederm hydro – the subjects were divided into five groups. Minimal phototoxic dose (MPD) was determined by irradiating two rows of six circular test fields on the back of the subjects with increasing doses of UVA. One of the emollients listed above was applied to the skin under the upper rows alternatively, whereas the lower rows served as control.

Results: Application of Urederm hydro and Decubal before exposure to UVA resulted in a statistically significant decrease in the MPD in all subjects. Even though application of white petrolatum and white petrolatum containing 3% salicylic acid decreased the MPD in most of the subjects and Balmandol application slightly increased the MPD, the results did not reach statistical significance.

Conclusions: According to our findings, it is probable that the total dose of UVA needed to cause clearing of psoriasis would be decreased by application of Urederm hydro and Decubal prior to photochemotherapy. We noted a slight photoprotective effect of Balmandol in the UVA range, but this finding has to be further studied. Clinical studies are needed to clarify the effects of these emollients on the course and outcome of photochemotherapy.
Determination of UVA protection factors using the persistent pigment darkening (PPD) as the end point
Authors: Moyal Dominique , Chardon Alain , Kollias Nikiforos
Published: March 2003

Background/Aims: The accuracy and reliability of any method to assess the UVA protection effectiveness of sunscreens needs to be demonstrated. The aim of the present study was to calibrate the effectiveness of a biological end point (Persistent Pigment Darkening, PPD) to assess UVA photoprotection.

Methods: Persistent Pigment Darkening was selected as the end point because its action spectrum extends across the UVA. A broad UVA source was chosen to challenge all UVA wavelengths. Attenuation of UVA was performed with neutral density filters (equally absorbing at all wavelengths). Human subjects were tested with a series of UVA beams attenuated by the neutral density filters. The UVA protection effectiveness of a standard sunscreen was also tested with four panels of volunteers to assess the reproducibility of the method.

Results: The attenuation factors of the neutral density filters were found to correspond to the UVA protection factors arrived at with PPD as the end point. The repetitive tests showed a good internal consistency of the method.

Conclusions: The calibration procedure proposed shows threshold PPD, used as an end point in a UVA‐PF test method, to be a reliable endogenous dosimeter for UVA radiation that enters the skin.
Balneophototherapy of psoriasis: highly concentrated salt water versus tap water – a randomized, one‐blind, right/left comparative study
Authors: Gambichler T. , Rapp S. , Senger E. , Altmeyer P. , Hoffmann K.
Published: March 2003

Background/Purpose: Apart from climatotherapy and spa therapy, combined treatment with salt water baths and artificial UV radiation (balneophototherapy) has been advocated for the treatment of psoriasis. As there is a lack of controlled studies on balneophototherapy (BPT), we conducted a randomized, one‐blind, right/left comparison with salt water versus tap water in order to investigate the significance of the salt concentration in the efficacy of BPT.

Methods: Ten psoriasis patients with chronic plaques on the elbows were included in the study. One elbow was soaked in 24% NaCl solution and the other in tap water. Subsequently, broadband UVB irradiation was administered. BPT was performed 4 times weekly with a total of 30 treatments.

Results: A highly significant (P<0.001) decrease of the clinical baseline score was observed after 30 treatments; however, there was no significant (P>0.5) difference in clearance of the psoriatic lesions between the sites soaked in salt water and tap water.

Conclusion: Our results suggest that any additional benefit of soaking in salt water and tap water in BPT are unlikely to be due to the salinity of the liquids.
In vivo measurement of the photostability of sunscreen products using diffuse reflectance spectroscopy
Authors: Moyal Dominique , Refrégier Jean‐Louis , Chardon Alain
Published: March 2003

Background/Aim: The issue of the photostability of sunscreens has been frequently raised because of the possible loss of photoprotection, mainly in the UVA range, during sun exposure. Up to now, in vitro techniques have been mainly proposed to evaluate photostability. These techniques have generated controversial debates concerning the predictive value of these in vitro observations in relation to the in vivo reality during sun exposure.

Methods: Diffuse reflectance spectroscopy (DRS) is a recently developed technique that allows measurement of the UVA efficacy of sunscreen products in vivo on human volunteers. The absorption spectrum of the product is obtained by measuring the change in reflection of the skin with and without product. From this absorption spectrum, the UVA protective efficacy of the test product can be calculated for an appropriate source and a given biological action spectrum. We have used the DRS technique in vivo to determine the photostability of sunscreen products by measuring reflection spectra in the UVA range (320–400 nm) before and after product application and before and after UV exposure of the test products. Comparison between these spectra or between the corresponding calculated UVA protection factors has made it possible to determine the remaining level of protection in the UVA range after exposure. This study was designed to compare in vivo the protective efficiency and the photostability of three marketed sunscreen products (SPF 23–30) after solar‐simulated exposure for SPF testing or after actual sun exposure. These in vivo data were then compared to in vitro photoinstability results.

Results: According to the in vitro measurements, one sunscreen product was found photostable and two products photo‐unstable. After UVe exposure for in vivo SPF determination, a decrease in UVA absorption and UVA‐PF was observed for the two photo‐unstable products, while the photostable product did not present any decrease in UVA absorption. These results were confirmed through exposure to actual sun.

Conclusion: Our study confirms the prediction of the in vitro methods previously used to assess the photostability of sunscreen products. In addition, DRS provides a powerful new tool for the in vivo simultaneous evaluation of photostability and estimation of the UVA protection factor of sunscreen products performed during the test for SPF determination.
Photoimmunosuppression
Authors: Schwarz T.
Published: March 2003

Ultraviolet (UV) radiation can exert a variety of biological effects, including induction of skin cancer, premature skin ageing and inhibition of the immune system. The immunosuppressive properties of UV radiation are of major biological relevance since suppression of the immune system by UV radiation is not only responsible for the exacerbation of infectious diseases following UV exposure, but also contributes to the induction of skin cancer. Hence, understanding of the mechanisms by which UV radiation compromises the immune system is of primary importance. UV radiation suppresses the immune system in multiple ways. It inhibits antigen presentation, stimulates the release of immunosuppressive cytokines and induces the generation of lymphocytes of the suppressor subtype. In the following, some of the basic mechanisms underlying UV‐induced immunosuppression will be discussed.
Melatonin reduces dinitrobenzene sulfonic acid‐induced colitis
Authors: Cuzzocrea Salvatore , Mazzon Emanuela , Serraino Ivana , Lepore Valeria , Luisa Terranova Maria , Ciccolo Antonio , Caputi Achille P.
Published: March 2003

Inflammatory bowel disease (IBD) is characterized by oxidative and nitrosative stress, leukocyte infiltration, and up‐regulation of intercellular adhesion molecule 1 (ICAM‐1) expression in the colon. The aim of this study was to examine the effects of the pineal secretory product melatonin in rats subjected to experimental colitis. Colitis was induced in rats by intracolonic instillation of dinitrobenzene sulfonic acid (DNBS). Rats experienced bloody diarrhea and a significant loss of body weight. Four days after DNBS administration, the colon damage was characterized by areas of mucosal necrosis. Neutrophil infiltration (indicated by myeloperoxidase [MPO] activity in the mucosa) was associated with up‐regulation of ICAM‐1, expression of P‐selectin, and high levels of malondialdehyde (MDA). Immunohistochemistry for nitrotyrosine and poly (ADP‐ribose) synthetase (PARS) showed an intense staining in the inflamed colon. Staining of colon tissue sections obtained from DNBS‐treated rats with an anti‐cycloxygenase‐2 (COX‐2) antibody showed a diffuse staining of the inflamed tissue. Furthermore, expression of inducible nitric oxide synthase (iNOS) was found mainly in the macrophages of the inflamed colons from DNBS‐treated rats. Treatment with melatonin (15 mg/kg daily, intraperitoneally) significantly reduced the appearance of diarrhea and the loss of body weight. This was associated with a remarkable amelioration of the disruption of the colonic architecture, as well as a significant reduction of colonic MPO activity and MDA levels. Melatonin also reduced the appearance of nitrotyrosine and PARS immunoreactivity in the colon, as well as reducing the up‐regulation of ICAM‐1 and the expression of P‐selectin. The intensity and degree of the stainings for COX‐2 and iNOS were markedly reduced in tissue sections obtained from melatonin‐treated rats. The results of the this study suggest that the administration of melatonin might be beneficial for the treatment of IBD.
Seasonal alterations in circadian melatonin rhythms of the European wild boar and domestic gilt
Authors: Tast Anssi , Hälli Outi , Ahlström Susanna , Andersson Håkan , Love Robert J. , Peltoniemi Olli A.T.
Published: March 2003

The aims of the present study were: 1) to determine if the European wild boar exhibits a circadian pattern of melatonin secretion under its natural light environment; 2) to compare this pattern with the pattern in domestic pigs reared under the light environment typical for domesticity; and 3) to determine if there are seasonal alterations in melatonin rhythms. Four to six young, pure‐bred, European wild boars and four to six cross‐bred (Yorkshire×Finnish Landrace) domestic gilts were sampled at 2‐hr intervals for 48 hr at the spring/autumn equinoxes and summer/winter solstices. Samples were obtained via saphenous arterial catheters from the wild boars and via ear vein catheters from the domestic gilts. The ambient light intensity was recorded simultaneously with sampling both outdoors and indoors. Following ether extraction, the serum samples were assayed for melatonin using a commercial RIA (Bühlman®). All the experimental animals exhibited a distinct circadian pattern in melatonin secretion, with high concentrations occurring during the scotophase. There was no difference in scotophase melatonin response between the wild boars and domestic gilts in any season in terms of mean melatonin concentration or peak value. The mean duration of increased melatonin secretion (more than two standard deviations over a mean photophase concentration) in 24 hr in the wild boars in spring, summer, autumn and winter, was 10, 6, 11 and 17 hr, respectively, and in the domestic gilts, 9, 8, 12 and 11 hr, respectively. These results demonstrate the existence of circadian rhythm in melatonin secretion in both the European wild boar and domestic pig. In both groups, the duration of secretion is subject to seasonal alterations. The results suggest no difference in photoperiodic‐melatonin transduction between the European wild boar and domestic pig whether due to altered genotype or reduced light environment.
A test of the coincidence and duration models of melatonin action in Siberian hamsters: the effects of 1‐hr melatonin infusions on testicular development in intact and pinealectomized prepubertal Phodopus sungorus
Authors: Gündüz Bülent , Stetson Milton H.
Published: March 2003

The pineal hormone melatonin is known to play an important role in mediating photoperiodic messages to the reproductive system in seasonal breeding animals. Our goal was to test, in a single experimental paradigm, two hypotheses that have been forwarded to describe how the circadian rhythm of pineal melatonin transmits photoperiodic information to the reproductive system: 1) induction, i.e., a short‐day effect, occurs when secreted melatonin and a circadian rhythm of sensitivity to melatonin coincide in time; 2) induction occurs following exposure to elevated circulating melatonin levels for a prescribed duration. In order to determine the relative validity of these hypotheses, we investigated the testicular maturation response to 1‐hr daily infusions of 10, 25, and 50 ng of melatonin in pinealectomized intact and prepubertal Siberian hamsters (Phodopus sungorus). Animals received, beginning on day 15 of life, programmed subcutaneous infusions of melatonin or vehicle at one of five time points (19:00–20:00, 20:00–21:00, 21:00–22:00, 24:00–01:00, and 03:00–04:00 hr) for 15 days. In animals gestated and raised in a long photoperiod (LD16:8=16L, where L is the duration of light in hours, and D that of dark), melatonin infusion right after lights off (20:00–21:00 hr) significantly retarded gonadal maturation; this dose was ineffective at other times tested. Doses of 10 and 25 ng melatonin were ineffective at all time points. Identical results were obtained in prepubertal hamsters gestated in a short photoperiod (LD10:14=10L) and raised in 16L; these results were independent of the presence or absence of the pineal gland. In animals gestated and raised in 10L, melatonin infusions failed to suppress testicular development beyond that induced by the photoperiod; testicular development was maximally suppressed in all groups. The results of these investigations are best explained under the experimental conditions employed here: 1) the photoperiodic gonadal response in juvenile Siberian hamsters is regulated by the coincidence in time of exogenously administered melatonin with an intrinsic rhythm of sensitivity to melatonin, which, under the constraints imposed by our experimental design, occurred at 20:00–21:00 hr; and 2) the duration of the melatonin signal alone, equal in all groups, cannot explain the results.
Melatonin versus vitamin E as protective treatment against oxidative stress after extra‐hepatic bile duct ligation in rats
Authors: Montilla P. , Cruz A. , Padillo F.J. , Túnez I. , Gascon F. , Muñoz M.C. , Gómez M. , Pera C.
Published: March 2003

The aims of the present study were first to compare the effects of melatonin and vitamin E on the cholestasis syndrome and their protective effect on liver injury, and second, to evaluate the activity of antioxidant enzymes after treatment with these antioxidant drugs. Cholestasis was achieved in adult male Wistar rats by double ligature and section of the extra‐hepatic biliary duct. Hepatic and plasma oxidative stress markers were evaluated by changes in the amount of lipid peroxides, measured as malondialdehyde (MDA) and reduced glutathione (GSH) in plasma and homogenates of hepatic tissue. Serum bilirubin, alkaline phosphatase (AP), and gamma‐glutamyl‐transpeptidase (GGT) were used to evaluate the severity of cholestasis, and serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were used to evaluate the hepatic injury. Both vitamin E and melatonin were administrated 1 day before and 7 days after bile duct ligation. Acute ligation of the bile duct was accompanied by a significant increased in MDA and a decrease in GSH levels in both plasma and liver, as well as a significant reduction in antioxidant enzymes activities. The overall analysis of both treatments showed that melatonin (500 μg/kg daily) offered significantly better protection against cholestasis and a superior protective effect on hepatic injury than did vitamin E (15 mg/kg daily). Although vitamin E treatment resulted in a reduction of parameters of oxidative stress, the results were significantly better after a much lower daily dose of melatonin. Moreover, melatonin treatment was associated with a significant recovery of antioxidative enzymes. In conclusion, the present paper demonstrates a correlation between the intensity of biliary tract obstruction and increased free radical generation, as well as a direct correlation between the level of oxidative stress and the biochemical markers of liver injury. Melatonin (at a much lower dose than vitamin E) was much more efficient than vitamin E in reducing the negative parameters of cholestasis, the degree of oxidative stress and provided a significantly greater hepatoprotective effect against the liver injury secondary to the acute ligation of the biliary duct.
Effects of melatonin on doxorubicin cytotoxicity in sensitive and pleiotropically resistant tumor cells
Authors: Granzotto Marilena , Rapozzi Valentina , Decorti Giuliana , Giraldi Tullio
Published: March 2003

Melatonin has been reported to attenuate the oxidative damage caused by doxorubicin on kidney, brain, heart and bone marrow, whereas the in vivo antitumor effects of doxorubicin were not attenuated. The effects of melatonin on doxorubicin cytotoxicity have, therefore, been examined on human normal mammary epithelium HBL‐100, on mammary adenocarcinoma MCF‐7, on colon carcinoma LoVo, and on mouse P388 leukemia cell lines, and on tumor cell sublines pleiotropically resistant to anthracyclines. Melatonin in the concentration range 10–2000 pg/mL causes an inhibition of the growth of the human cell lines examined which is not clearly dose‐dependent and less than 25% when significant. Melatonin similarly causes minor effects on doxorubicin cytotoxicity either on the parental human cell lines or on their resistant sublines. On the contrary, 200–1000 pg/mL melatonin cause a significant and dose‐dependent partial sensitization to doxorubicin of resistant P388 mouse leukemia (P388/ADR), which occurs also in vivo, as indicated by a significant increase in survival time of the hosts. Doxorubicin intracellular concentrations in P388/ADR cells are increased by melatonin, suggesting that melatonin might inhibit P‐glycoprotein‐mediated doxorubicin efflux from the cells. These results indicate that the use of melatonin in clinical cancer treatment should not pose the risk of an attenuation of the effectiveness of doxorubicin, and encourage the further examination of the possible reduction by melatonin of the host toxicity of antitumor chemotherapy.
Melatonin protects against cardiac toxicity of doxorubicin in rat
Authors: Xu Mei Feng , Ho Susan , Qian Zhong Ming , Tang Pak Lai
Published: March 2003

Doxorubicin (DOX) is commonly used for the treatment of hematological and solid tumors. However, there are serious toxic effects on the cardiovascular system, which limits the application of the drug. Recently, melatonin has been reported to have immunomodulatory effect in addition to lowering cholesterol levels as well as inhibiting malignant tumors. In this study, the effect of melatonin against the toxicity of doxorubicin was investigated in rats. Hemodynamic function, pathological and biochemical changes were determined in different treated hearts. Our findings showed that a significant protection by melatonin (6 mg kg−1 for 15 days, cumulative dose of 90 mg kg−1) against the DOX‐induced toxicity was observed. Cardiac function was improved and lipid peroxidation decreased after melatonin treatment. It is concluded that melatonin provides protection against doxorubicin toxicity via an attenuation of lipid peroxidation.
Norepinephrine‐dependent phosphorylation of the transcription factor cyclic adenosine monophosphate responsive element‐binding protein in bovine pinealocytes
Authors: Schomerus Christof , Laedtke Elke , Korf Horst‐Werner
Published: March 2003

Abstract:  Norepinephrine (NE)‐dependent activation of transcription factors is of central importance for the rhythmic production of melatonin in the rodent pineal gland. At variance with rodents, NE regulates melatonin biosynthesis through post‐translational mechanisms in ungulates, and it is not yet known whether transcription factors play any role in ungulate pineal functions. Here, we investigated in isolated bovine pinealocytes the NE‐dependent phosphorylation of the transcription factor cyclic adenosine monophosphate (cAMP) responsive element‐binding protein (CREB) and compared the effects of NE with those of vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase‐activating polypeptide (PACAP). Treatment with 10−7 m NE for 30 min induced a strong nuclear phosphorylated CREB (pCREB) immunoreaction in cells that were identified as pinealocytes by immunocytochemical demonstration of serotonin, a pinealocyte‐specific marker. Immunoblots showed that the NE‐induced immunoreaction was due to phosphorylation of the transcription factor CREB and another protein, presumably the activating transcription factor 1 (ATF‐1). 10−7 m isoproterenol (ISO) or 10−5 m forskolin mimicked the response to NE indicating that NE acts through the β‐adrenergic/cAMP pathway. Also 10−7 m PACAP, but not 10−7 m VIP‐enhanced CREB phosphorylation; however, only a subpopulation of cells was responsive to PACAP. Our results suggest that, irrespective of whether or not melatonin production is controlled via transcriptional mechanisms, NE‐induced CREB phosphorylation represents a very conserved element in pineal physiology of mammals because NE increases pCREB levels in all mammalian species investigated so far. However, the genes targeted by pCREB may vary from one mammalian species to the other. Our results also suggest that transcription factors other than pCREB, like ATF‐1, may play a role in pineal functions of mammals.
The utility of melatonin in reducing cerebral damage resulting from ischemia and reperfusion
Authors: Cheung Raymond Tak Fai
Published: March 2003

Abstract: The brain is highly susceptible to focal or global ischemia. Unless ischemia is promptly reversed, reperfusion produces further cerebral damage. Acute thrombolysis or defibrinogenation is effective only in selective patients with ischemic stroke and carries a significant risk of bleeding complications. Whereas numerous neuroprotectants were shown to be effective in experimental studies, none of them have been shown to work in clinical trials. The major pathogenetic mechanisms of ischemia/reperfusion injury include excitotoxicity, disturbed calcium ion homeostasis, overproduction of nitric oxide and other free radicals, inflammation, and apoptosis. Nitric oxide and other free radicals, the key mediators of excitotoxicity and disturbed calcium ion homeostasis, cause direct injury and also indirectly damage via inflammation and apoptosis. Melatonin is a potent free radical scavenger and an indirect antioxidant. This mini review summarizes the in vivo and in vitro evidence that melatonin protects against ischemia/reperfusion injury. There is convincing evidence from the literature that melatonin treatment is highly effective in different in vivo and in vitro models of excitotoxicity or ischemia/reperfusion in multiple animal species. Melatonin is safe and non‐toxic in humans, and its administration via the oral route or intravenous injection is convenient. While more experimental studies should be conducted to further explore the neuroprotective mechanisms and to document any synergistic or additive protection from combining melatonin with thrombolysis, defibrinogenation or other neuroprotectants, interested clinical scientists should consider planning phase II and III studies to confirm the benefit of melatonin as an acute stroke treatment or a preventive measure for stroke patients.
Oxidation of melatonin by carbonate radicals and chemiluminescence emitted during pyrrole ring cleavage
Authors: Hardeland Rüdiger , Poeggeler Burkhard , Niebergall Robert , Zelosko Veronika
Published: March 2003

Abstract: Oxidation of melatonin was followed by measuring chemiluminescence emitted during pyrrole ring cleavage, a process leading to the main oxidation product of this indoleamine, N1‐acetyl‐N2‐formyl‐5‐methoxykynuramine (AFMK). Radical reactions of melatonin were studied in two variants of a moderately alkaline (pH 8) H2O2 system, one of which contained hemin as a catalyst. In both systems, light emission from melatonin oxidation lasted several hours. Time courses and turnover rates depended on the presence or absence of hemin; the catalyst enhanced light emission many‐fold. In the two reaction systems, the presence of hydrogen carbonate (HCO) enhanced chemiluminescence by more than 10‐fold, indicating scavenging of carbonate radicals. In the presence of 10% dimethylsulfoxide (DMSO) or 1 m mannitol, HCO‐dependent as well as independent light emissions were only partially inhibited. With regard to the stimulatory effect of HCO, this implies a formation of carbonate radicals () independent of hydroxyl (ḃOH) radicals, presumably involving superoxide anions abundantly present in the system. Tiron, a scavenger of superoxide anions, strongly and almost instantaneously inhibited chemiluminescence, in accordance to the requirement of this reactive oxygen species for AFMK formation and its involvement in ‐radical formation. Melatonin's capability of scavenging CO may contribute to its protective potency.
Left ventricular mass, geometry and filling in elite female and male endurance athletes
Authors: Stolt A. , Karjalainen J. , Heinonen O. J. , Kujala U. M.
Published: March 2003

We compared echocardiographic findings in female (n=30) and male (n=30) endurance athletes to age‐matched female (n=15) and male (n=15) sedentary controls. The differences between athletes and controls were similar in both sexes; only left ventricular (LV) mass and septum thickness differed slightly more in men than in women (67% vs 55%, P=0.004, and 36% vs 30%, P=0.03, respectively). LV wall thicknesses were in the normal range in all women, while four (13%) male athletes exceeded 13 mm. In conclusion, the effects of endurance training on echocardiographic findings appear to be quite similar in women and men. However, in female athletes with an abnormally thick left ventricular wall a thorough cardiac evaluation is indicated. This contrasts with male athletes, in whom LV wall thicknesses of over 13 mm are a not uncommon finding.
The continuity of physical activity – a retrospective and prospective study among older people
Authors: Hirvensalo M. , Lintunen T. , Rantanen T.
Published: March 2003

This study investigated the continuity of life‐span physical activity by examining the predictors of the maintenance of a high level of physical activity over 8 years among subjects aged 65–84 years at the baseline, in 1988, in Jyväskylä, Finland. Age, education, marital status and chronic conditions and past physical activity were studied at the baseline. In men and women, self‐reported competitive sport participation from as early as 10–19 years of age was a significant predictor for maintaining activity in old age. Also women’s participation in recreational sports at the age of 40–64 years predicted activity. We concluded that past physical activity is strongly connected to maintaining a high level of physical activity in old age regardless of chronic conditions that may develop.