bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of date extract on adhesion of Candida species to human buccal epithelial cells in vitro
Authors: Abu‐Elteen Khaled H.
Published: March 2003

Abstract: The adherence of three Candida species to human buccal epithelial cells (BEC) following treatment with different concentrations of date extract was investigated in vitro, as well as the effect of a mouth rinse with date extract on the adhesion of yeast to BEC. Adhesion of C.albicans, C.tropicalis and C.kefyr to BEC was significantly reduced after both short‐ and long‐term periods of yeast exposure to various concentrations of date extract (reduction between 25% and 52% of the control value). A similar inhibition of adherence was observed upon pre‐incubation of BEC with date extract. There was a significant reduction (P<0.001) in the adherence of yeast to BEC collected immediately or 5–20 min after an oral rinse with 10% date extract. No statistically significant difference was observed in the adhesion of BEC collected 30 min after an oral rinse with date extract and control BEC. In addition, pre‐treatment of either Candida or BEC, or both, with date extract resulted in reduced adherence, the magnitude of which was largest when both types of cells were pre‐treated. Date extract also inhibited germ‐tube formation of C. albicans (56–85% inhibition), which might contribute to the effects on adherence.
Decline in the rate of oral opportunistic infections following introduction of highly active antiretroviral therapy
Authors: Schmidt‐Westhausen Andrea M. , Priepke Frank , Bergmann Frank J. , Reichart Peter A.
Published: March 2003

Abstract: In recent years the management of human immunodeficiency virus (HIV)‐positive individuals has been based on highly active antiretroviral therapy (HAART) comprising a combination of nucleoside analogues or the combination of these agents with protease inhibitors. The aim of the present study was to describe the prevalence of oral lesions in a cohort of 103 HIV‐seropositive patients on HAART, to compare these data with the prevalence of lesions prior to HAART and to correlate these finding with the immunologic data. A total of 103 HIV‐seropositive patients on HAART were selected. Oral lesions associated with HIV infection and immunological parameters were registered. On re‐examination 6 months after the first evaluation, 61/103 patients were available. Comparing the prevalence of oral lesions before and after the onset of HAART, the number of oral lesions was significantly lower (P=0.001). The number of CD4+ cells increased and the viral load decreased significantly after initiation of HAART (P=0.001 and P=0.0001). On re‐examination 6 months later, the prevalence of lesions again decreased significantly (P=0.001). The immunological benefits of HAART may prevent HIV‐associated oral lesions in patients with advanced HIV disease. Our results showed that oral manifestations decrease on HAART, but in four patients the immunological effects of therapy did not provide sufficient protection against human papillomavirus (HPV)‐induced lesions.
Immunohistochemical study of the distribution of endogenous biotin and biotin‐binding enzymes in ductal structures of salivary gland tumours
Authors: Lu Chang‐Sheng , Kashima Kenji , Daa Tsutomu , Yokoyama Shigeo , Yanagisawa Shigetaka , Nakayama Iwao
Published: March 2003

Abstract: To clarify the pathologic value of endogenous biotin in the salivary gland, we examined in a series of neoplasms of the salivary gland by immunohistochemical staining the distribution of endogenous biotin and of biotin‐binding enzymes, namely, acetyl CoA carboxylase (AC), which is a cytosolic enzyme, and pyruvate carboxylase (PC), which is a mitochondrial enzyme. In pleomorphic adenoma, we found biotin and PC in ductal epithelial elements, while AC was found mainly in myoepithelial elements. Carcinoma ex pleomorphic adenoma, adenocarcinoma and mucoepidermoid carcinoma were frequently immunopositive for biotin, PC and AC, while adenoid cystic carcinoma was rarely immunopositive for biotin, PC or AC. These results indicate that endogenous biotin might be associated with the mitochondrial enzyme, which is present at high levels in ductal cells of the salivary gland. However, the neoplastic cells in adenoid cystic carcinoma seemed to have an unusual expression of biotin and related enzymes.
Effect of the single major proteic fractions of the liver perchloric extract UK101 on the development of oral tumours in Syrian hamsters
Authors: Berta Giovanni N. , Di Carlo Francesco , Bosio Anita , Corvetti Giovanna , Cesano Luigi , Arzani Camilla , Bailo Mariangela , Mognetti Barbara , Bartorelli Alberto , Ghezzo Franco
Published: March 2003

Abstract: Squamous cell carcinoma of the oral cavity continues to be a major clinical problem, with about 100,000 new deaths each year worldwide. There is therefore a need to search for new tools to aid oral cancer treatment. We tested the inhibitory activity on chemical carcinogenesis of the three principal protein fractions of about 50, 14, and 8.5 kDa of the mixture UK101 derived from goat liver. These are composed principally of a glycoprotein rich in mannose residues, a protein with analogy to the heat shock protein family, and ubiquitin, respectively. The animal model employed was dimethylbenzanthracene‐induced hamster cheek pouch carcinoma. Number of tumours per animal, tumour mass per animal, and proliferating cell nuclear antigen (PCNA) in non‐tumour mucosa were quantified: the 14‐kDa fraction was the most active; this was also confirmed by testing its corresponding recombinant material. The 50‐kDa fraction was inactive, while the ubiquitin showed only low inhibitory activity. It is possible that the technique described and the results obtained could lead to an interesting clinical approach to the treatment of oral cancer.
Nitric oxide signalling in salivary glands
Authors: Looms Dagnia , Tritsaris Katerina , Pedersen Anne Marie , Nauntofte Birgitte , Dissing Steen
Published: March 2003

Nitric oxide (NO) plays multiple roles in both intracellular and extracellular signalling mechanisms with implications for health and disease. This review focuses on the role of NO signalling in salivary secretion. Attention will be paid primarily to endogenous NO production in acinar cells resulting from specific receptor stimulation and to NO‐regulated Ca2+ homeostasis. Due to the fact that NO readily crosses membranes by simple diffusion, endogenous NO may play a physiological role in processes as diverse as modifying the secretory output, controlling blood supply to the gland, modulating transmitter output from nerve endings, participating in the host defence barrier, and affecting growth and differentiation of surrounding tissue. Furthermore, the role of NO in the pathogenesis of human oral diseases will be considered.
Which putatively pre‐malignant oral lesions become oral cancers?
Authors: Sudbø Jon , Reith Albrecht
Published: March 2003

Oral squamous cell carcinomas continue to be a group of diseases with high mortality and increasing incidence rates, particularly among young individuals. This is a paradox finding, since most oral cancers are preceded – even by several years – by readily detectable mucosal changes, most often white or red patches (leukoplakias and erythroplakias, respectively). However, only a small fraction of leukoplakias or erythroplakias are related to cancer development, and the challenge has been to identify the high‐risk lesions. From the vast literature on molecular markers in oral pre‐cancer, no reliable prognostic marker for risk assessment in putatively pre‐malignant lesions has emerged. For this reason, a wait‐and‐see approach has been adopted for this group of lesions. Recently published data point to gross genomic aberrations (DNA aneuploidy) as a tool for targeting patients at particular risk for future cancerous lesions in the oral cavity. Thus, DNA aneuploidy signalled a very high risk for subsequent development of carcinomas in a wide range of lesions from the oral mucous membrane, ranging from oral leukoplakias to oral erythroplakias and even including lesions that had been explicitly defined as being without a malignant potential by a group of trained pathologists. As an extension of research in oral pre‐malignancies, the enzyme cyclooxygenase‐2 (COX‐2) seems to be enhanced specifically in high‐risk oral lesions, as defined by the aberrant DNA content of their lesions. These data strongly indicate that COX‐2 inhibitors (coxibs) should be investigated as chemopreventive agents in patients identified to be at high risk of developing oral cancer.
Regulation of the Murine Silver Locus Product (gp87) by the Hypopigmenting Cytokines TGF‐β1 and TNF‐α
Authors: MARTÍNEZ‐ESPARZA MARÍA , JIMÉNEZ‐CERVANTES CELIA , SOLANO FRANCISCO , LOZANO JOSÉ A. , GARCÍA‐BORRÓN JOSÉ C.
Published: March 2003

The melanosomal proteins encoded by the silver (si, SILV, or PMEL17) locus play important roles in melanogenesis and are actively investigated as targets for melanoma immunotherapy. The human silver locus yields two proteins, gp100 and PMEL17, by alternative splicing of a common mRNA precursor. Mouse melanocytes exclusively express the gp100 orthologue, here termed gp87, thus providing a simpler model with which to study the silver locus products. We have analyzed the effects of [Nle4,
d‐Phe7]‐α melanocyte‐stimulating hormone (αMSH) and two hypopigmenting cytokines, tumor necrosis factor (TNF)‐α and transforming growth factor (TGF)‐β1, on the expression of gp87 in B16 mouse melanoma cells. TNF‐α and TGF‐β1 (at saturating doses for 48 hr) decreased gp87 mRNA by 50%. The gp87 protein was almost undetectable by Western immunoblotting after TNF‐α treatment, but was not affected by TGF‐β1. αMSH increased the mRNA and the gp87 protein ∼2‐fold. Moreover, the amount of gp87 was not reduced by TNF‐α in the presence of the hormone, in spite of a 50% decrease in its mRNA. Therefore, the levels of mRNA and gp87 protein did not correlate after treatment with the cytokines. Overall, our data suggest that the silver locus product is not regulated exclusively at the transcriptional level, and highlight the importance of still‐uncharacterized regulatory translational and/or post‐translational events.
MITF: A Stream Flowing for Pigment Cells
Authors: TACHIBANA MASAYOSHI
Published: March 2003

Microphthalmia‐associated t

ranscription f

actor (MITF) is a transcription factor with a basic‐helix‐loop‐helix‐leucine zipper (bHLHZip) structure. Mutations of the MITF gene cause a variety of phenotypes, most notably in pigmented cells, in several species. In humans, haploinsufficiency of MITF causes Waardenburg syndrome type 2, while a dominant‐negative mutation causes Tietz syndrome. Four isoforms have been cloned so far: MITF‐M is the most abundant and is expressed in neural‐crest‐derived melanocytes; MITF‐A is expressed in various cultured cells including retinal pigment epithelium (RPE) and enriched in RPE of embryonal and developing eyes; MITF‐H are expressed in many types of cultured cells and in the heart tissue; MITF‐C is expressed in many types of cultured cells, but not in melanocytes. Many growth factor signaling pathways have been implicated for regulation of MITF at both protein and promoter levels. Most notably, Steel factor/c‐Kit signaling pathway was linked to phosphorylation of MITF at Ser73 and Ser409 through activation of MAP kinase and RSK‐1, respectively. Phosphorylation of MITF is also conducted at Ser298 through GSK3β, although the signaling pathway for this event still remains to be elucidated. IGF‐1 and HGF/SF pathways may merge with the c‐Kit signaling pathway. WNT and MSH signaling pathways regulate MITF positively at the promoter level. Endothelins may regulate MITF at the protein and promoter levels. MITF is involved in the differentiation, growth and survival of pigment cells, employing a number of signaling pathways.
The Inbred Mouse in Pigmentation Research:
Authors: LAMOREUX M. LYNN
Published: March 2003

Pigment mutations in inbred mice have been important to many new scientific developments over the past century. Inbred mice are essentially genetically alike because of 10–20 generations or more of sibling mating or the equivalent. Mice of the same inbred strain that differ at only one locus can be used to evaluate the phenotypic effects of that one locus without complication of variation at other loci. Similarly, genic interactions among the functions of two or more loci are evaluated by comparing them in all combinations against a uniform genetic background. The next logical step in describing the pigment system will occur when all pigment cell biologists who use mice (cells, tissues, DNA, RNA) make certain that their mice are congenic with C57BL/6J. As a result, the work of all investigators will be genetically comparable. Their work will also be comparable to those investigating other organ systems, because NIH has chosen C57BL/6J as one of its two standard strains. As a result of this standardization, interactions among the different gene loci that function in the pigment system will become more readily evident and the community of pigment cell biologists using congenic mice will be able to analyze the functional interplay of loci that regulate the entire pigment system in the same way that earlier researchers analyzed one mutant allele, or the interactions of two mutant loci.
Spleen and Liver Pigmented Macrophages of Rana Esculenta L. A New Melanogenic System?
Authors: Gallone Anna , Guida Gabriella , Maida Immacolata , Cicero Rosa
Published: March 2003

The present study reports the results of a morpho‐functional analysis of spleen pigmented cells from Rana esculenta L. and comparison with liver melanin‐synthesizing cells, belonging to the macrophage cell lineage. Cytological and cytochemical analyses show that parenchymal pigmented cells of the spleen, like those of the liver, are positive to peroxidase and lipase reactions and have phagocytic properties. The observation of premelanosomes in various stages of differentiation, together with the demonstration of dopa oxidase activity in the melanosome proteins, indicate that spleen pigmented macrophages have endogenous melanogenic ability as do liver pigmented macrophages. Attempts to demonstrate tyrosine‐hydroxylase activity in melanosome protein extracts from frog spleen and liver, using the same protocol as for mammalian tyrosinases, gave negative results. As regards the dopa oxidase activity revealed, some of its properties differ from the typical behaviour observed for tyrosinases from different sources. Peroxidase activity is shown in spleen and liver melanosome proteins with p‐phenylenediamine‐pyrocatechol (PPD‐PC), and not with typical peroxidase substrates. Suitable inhibition tests revealed that dopa oxidase and peroxidase activities might be supported by two different proteins. Liver melanosome extracts display a very strong laccase (dimethoxyphenol‐oxidase) activity but spleen extracts do not. Differences observed in the enzymatic properties of the spleen and liver melanosomes suggest that pigmented macrophages may undergo tissue‐specific differentiation. These preliminary data show that the melanin pathway of pigmented macrophages is different from that of melanocytes and may pave the way to identification of a new melanogenic pathway in vertebrates.
Modulation of Melanogenesis by Aloesin: A Competitive Inhibitor of Tyrosinase
Authors: Jones Ken , Hughes Jennifer , Hong Mei , Jia Qi , Orndorff Steve
Published: March 2003

Aloesin, [2‐acetonyl‐8‐β‐d‐glucopyranosyl‐7‐hydroxy‐5‐methylchromone], a compound isolated from the Aloe plant, is shown in these studies to modulate melanogenesis via competitive inhibition of tyrosinase. Aloesin inhibits purified tyrosinase enzyme and specifically inhibits melanin production in vitro. Enzyme kinetics studies using normal human melanocyte cell lysates and cell‐based melanin production demonstrated that aloesin is a competitive inhibitor of tyrosinase from mushroom, human and murine sources. Tyrosine hydroxylase and 3,4‐dihydroxyphenylalanine (DOPA) oxidase activities of tyrosinase from normal human melanocyte cell lysates were inhibited by aloesin in a dose dependent manner. In a percutaneous absorption study a finite dose of aloesin penetrated the skin slowly and was recovered primarily in the surface wash. Aloesin shows promise as a pigmentation‐altering agent for cosmetic or therapeutic applications.
Melanin has a Role in Ca2+ Homeostasis in Human Melanocytes
Authors: Hoogduijn M. J. , Smit N. P. , Van Der Laarse A. , Van Nieuwpoort A. F. , Wood J. M. , Thody A. J.
Published: March 2003

We have examined whether melanin affects Ca2+ homeostasis in cultured normal human melanocytes. Intracellular Ca2+ concentrations ([Ca2+]i), were measured in four Caucasian and in three Negroid melanocyte cultures. Under resting conditions [Ca2+]i was around 100 nM in all cultures, but differences between cells within cultures were observed. All cultures responded to endothelin‐1 (ET‐1) with increases in [Ca2+]i and there were no differences between Caucasian and Negroid cultures. However, large differences in responses between cells within cultures were observed, indicating that melanocyte cultures are very heterogeneous. The addition of 2.5 mM CaCl2 to melanocytes kept in Ca2+‐free medium resulted in rapid and transient increases in [Ca2+]i of up to 1500 nM. These increases were on average more than two times smaller in melanocyte cultures established from Negroid donors compared with Caucasian cultures. In addition, well melanized Caucasian melanocytes, cultured in the presence of 400 μM tyrosine and 10 mM NH4Cl, showed a reduced increase in cytoplasmic Ca2+ concentration upon the addition of extracellular Ca2+. The difference in maintaining Ca2+ homeostasis between poorly and well melanized melanocytes may be the result of the clearance of cytoplasmic Ca2+ into melanosomes and the greater capacity for this in the more pigmented melanocytes.
Evidence for an Autoimmune Pathogenesis of Vitiligo
Authors: Ongenae Katia , Van Geel Nanny , Naeyaert Jean‐Marie
Published: March 2003

Vitiligo is a depigmenting disorder characterized by the development of white patches in various distributions, which are due to the loss of melanocytes from the epidermis. A variety of arguments from clinical observations to research findings in human and animal models support the hypothesis of autoimmunity and are reviewed in this article. The association with autoimmune diseases and organ‐specific autoantibodies is well known. Various effective treatment options have an immunosuppressive effect. Today the autoimmune pathogenesis of the disease has become a rapidly evolving field of research. Detection of circulating melanocyte antibodies in human and animal models implicates a possible role of humoral immunity. Histological and immunohistochemical studies in perilesional skin suggest the involvement of cellular immunity in vitiligo. Recently, T‐cell analyses in peripheral blood further support this hypothesis. Interestingly, new insights in the association of vitiligo and melanoma may help to clarify the role of autoimmunity in the development of vitiligo.
Costimulatory molecules in human periodontal disease tissues
Authors: Gemmell E. , McHugh G. B. , Grieco D. A. , Seymour G. J.
Published: March 2003

An immunoperoxidase technique was used to examine CD28, CD152, CD80 and CD86 positive cells in gingival biopsies from 21 healthy/gingivitis and 26 periodontitis subjects. The samples were placed into 3 groups (small, intermediate, large) according to the size of the infiltrate. The percent CD28+ T cells in the connective tissue infiltrates was highly variable with no differences between the healthy/gingivitis and periodontitis groups. While there was an increase in positive cells in intermediate infiltrates from both healthy/gingivitis (28.5%) and periodontitis (21.4%) patients compared with small infiltrates (8.6% and 11.8%, respectively), this was not significant, although the percent CD28+ T cells did increase significantly in tissues with increased proportions of B cells relative to T cells (p=0.047). A mean of less than 5% infiltrating T cells were CD152+ which was significantly lower than the mean percent CD28+ T cells in intermediate healthy/gingivitis lesions (p=0.021). The mean percent CD80+ and CD86+ B cells and macrophages was 1–7% and 8–16%, respectively, the difference being significant in intermediate healthy/gingivitis tissues (p=0.012). Analysis of these cells in relation to increasing numbers of B cells in proportion to T cells and also to macrophages, suggested that CD80 was expressed predominantly by macrophages while CD86 was expressed by both macrophages and B cells. Few endothelial cells expressed CD80 or CD86. Keratinocytes displayed cytoplasmic staining of CD80 rather than CD86 although the numbers of positive specimens in the healthy/gingivitis and periodontitis groups reduced with increasing inflammation. In conclusion, percentages of CD28, CD152, CD80 and CD86 did not reflect differences in clinical status. However, the percent CD28+ T cells increased with increasing size of infiltrate and with increasing proportions of B cells suggesting increased T/B cell interactions with increasing inflammation. The percent CD152+ cells remained low indicating that CD152 may not be involved in negative regulation of T cells in periodontal disease. CD80 and CD86 have been reported to promote Th1 and Th2 responses, respectively, and the higher percent CD86+ cells suggests a predominance of Th2 responses in both healthy/gingivitis and periodontitis tissues. Nevertheless, other factors including cytokines themselves and chemokines which modulate T cell cytokine profiles must be monitored to determine the nature of Th1/Th2 responses in periodontal disease.
Platelet‐rich plasma and bovine porous bone mineral combined with guided tissue regeneration in the treatment of intrabony defects in humans
Authors: Camargo Paulo M. , Lekovic Vojislav , Weinlaender Michael , Vasilic Nikola , Madzarevic Miroslav , Kenney E. Barrie
Published: March 2003

Background:
A combination of platelet‐rich plasma (PRP), bovine porous bone mineral (BPBM) and guided tissue regeneration (GTR) has been shown to be effective in promoting clinical signs of periodontal regeneration in intrabony defects. As an initial attempt to clarify the role played by each of the three treatment components, this study was performed to compare the clinical effectiveness of two regenerative techniques for intrabony defects in humans: a combination of PRP/BPBM/GTR vs. GTR.

Material and methods:
  Eighteen patients participated in the study. Using a split‐mouth design, interproximal bony defects were surgically treated with either an absorbable membrane made of polylactic acid for GTR or a combination of PRP/BPBM/GTR. Changes in pocket depth, attachment level and defect fill as revealed by 6‐month reentry surgeries were evaluated.

Results:
  Both treatment modalities resulted in significant pocket depth reduction and clinical attachment gain as compared to baseline values. Pocket depth reduction was 4.98 ± 0.96 mm on buccal and 4.93 ± 0.92 mm on lingual sites of the PRP/BPBM/GTR group and 3.62 ± 0.81 mm on buccal and 3.54 ± 0.88 mm on lingual sites of the GTR group. The gain in clinical attachment observed was 4.37 ± 1.31 mm on buccal and 4.28 ± 1.33 mm on lingual sites of the PRP/BPBM/GTR group and 2.62 ± 1.23 mm on buccal and 2.44 ± 1.21 mm on lingual sites of the GTR group. The amount of defect fill observed was 4.78 ± 1.26 mm on buccal and 4.66 ± 1.32 mm on lingual sites of the PRP/BPBM/GTR group and 2.31 ± 0.76 mm on buccal and 2.26 ± 0.81 mm on lingual sites of the GTR group. All differences between the two groups were statistically significant in favor of the PRP/BPBM/GTR group.

Conclusions:
The results of this study suggest that PRP and BPBM provide an added regenerative effect to GTR in promoting the clinical resolution of intrabony defects on patients with severe periodontitis.
A systematic review of guided tissue regeneration for periodontal infrabony defects
Authors: Needleman Ian , Tucker Richard , Giedrys‐Leeper Elaine , Worthington Helen
Published: March 2003

Objectives: To systematically review the evidence for efficacy of guided tissue regeneration (GTR) for infrabony defects.

Background: The evidence for the efficacy of GTR has not yet been systematically appraised.

Methods: We searched for randomised controlled trials of at least 12 months' follow‐up comparing GTR with open flap debridement (OFD). Data sources included electronic databases, hand‐searched journals and contact with experts. Screening, data abstraction and quality assessment were conducted independently by multiple reviewers. The primary outcome measure was gain in clinical attachment.

Results: For attachment level change, the weighted mean difference between GTR alone and open flap debridement was 1.11 mm (95% CI: 0.63–1.59), chi‐square for heterogeneity 31.4 (9 df ), P < 0.001) and for GTR + bone substitutes was 1.25 mm (95% CI: 0.89–1.61, chi‐square for heterogeneity 0.01 (1 df), P = 0.91). The number of sites needed to treat (NNT) for GTR to achieve one extra site gaining 2 mm or more attachment over open flap debridement was 8 (95% CI: 4–33). Heterogeneity between studies was highly statistically significant for all principal comparisons and could not be explained satisfactorily by sensitivity analyses.

Conclusions: Overall, GTR was more effective than OFD in improving attachment levels. However, there was marked variability between studies and general conclusions about the clinical benefit of GTR are limited by this heterogeneity. Future studies should aim to identify factors associated with achieving consistent benefits over open flap debridement. Open flap surgery should remain the control comparison in these studies.
Inhibitory Effect of Melatonin on Homocysteine‐Induced Lipid Peroxidation in Rat Brain Homogenates
Authors: Osuna Carmen , Reiter Russel J. , García Joaquin J. , Karbownik Malgorzata , Tan Dun Xian , Calvo Juan R. , Manchester Lucien C.
Published: March 2003

Abstract:Oxidative damage is implicated in several pathologies including cardiovascular disease. As a model system to study the response of cells to oxidative insults, homocysteine toxicity was examined since it is an independent risk factor for atherosclerotic disease. The levels of malondialdehyde and 4‐hydroxyalkenals were assayed as an index of oxidatively damaged lipid. Inin vitroexperiments, the increase of lipid peroxidation products induced by homocysteine were concentration‐ and time‐dependent. To study the protective effect of melatonin on homocystine induced lipid peroxidation, brain homogenates were treated with different concentrations of melatonin. The accumulation of malondialdehyde and 4‐hydroxyalkenals induced by homocysteine was significantly reduced by melatonin in a concentration‐dependent manner. Additionally, a melatonin concentration of 1.5 mM reduced the levels of oxidatively damaged lipid products below those measured in control homogenates (no homocysteine, no melatonin). These data suggest that melatonin, an endogenous antioxidant may have a role in protecting cells from oxidative damage due to homocysteine and they support the idea that pharmacological concentrations could be used as a therapeutic agent in reducing cardiovascular disease where homocysteine may be a causative or contributing agent.
IgE‐Mediated Asthma and Rhinitis I: A Role of Allergen Exposure?
Authors: Nielsen Gunnar D. , Hansen Jitka S. , Lund Rikke M. , Bergqvist Mette , Larsen Søren T. , Clausen Susanne K. , Thygesen Peter , Poulsen Otto M.
Published: March 2003

Abstract: Exposures to airborne protein antigens, aeroallergens, may cause sensitization with production of Th2‐dependent antibodies, including IgE. The IgE antibodies and associated cellular responses are responsible for the allergic airway diseases, allergic rhinitis and allergic asthma, which are increasing in societies with Western life style. Aeroallergens may have different potential to sensitize exposed subjects. Thus, there are only a limited number of important groups of aeroallergens, which are those from house dust mites, cockroaches, pets, pollens, and moulds. Allergy follows to a certain extent the pharmacological/toxicological paradigm of dose‐response relationship. Unlike effects of pharmacologically and toxicologically active substances, allergens elicit their adverse effects in a two‐stage process. In the first stage the immunologically naïve individual is sensitized to the allergen. In the second stage renewed exposure to the allergen elicits the disease response. Also, high concentrations of aeroallergens may induce immunological tolerance. The scientific literature suggests that many environmental factors contribute to the increase in sensitization and development of airway allergies. Nevertheless, the dose‐response relationships apply (within certain limits) both to the sensitization itself and to the exacerbation of the diseases. This suggest that exposure reduction may be one of the methods for reduction of risk, in relation to control of the allergic airway diseases.
Effects of Lithium Carbonate on Apomorphine‐Induced Sniffing Behaviour in Rats
Authors: Fazli‐Tabaei Soheila , Yahyavi Seyed‐Hossein , Zarrindast Mohammad‐Reza
Published: March 2003

Abstract: Effects of lithium carbonate (Li2CO3) on sniffing induced by apomorphine have been tested in rats. Intraperitoneal administration of different doses of apomorphine (0.25, 0.5 and 1 mg/kg) induced a dose‐dependent sniffing response. Chronic Li2CO3 exposure (0.1% in drinking water for 30–35 days) but not acute administration of the drug (320 mg/kg, intraperitoneally) decreased the response of apomorphine. The response to chronic Li2CO3 exposure was observed when apomorphine was injected 60 min., 24 hr or 72 hr after Li2CO3withdrawal, with maximum effect observed when the drug was administered 72 hr after withdrawal of Li2CO3. Blockade of sniffing induced by apomorphine by the D1 dopamine receptor antagonist, SCH23390 (0.005 mg/kg, intraperitoneally) or the D2 dopamine receptor antagonist, sulpiride (25 mg/kg, intraperitoneally) was not increased in acute Li2CO3‐treated animals. In animals which were treated chronically with Li2CO3, the blockade of apomorphine response by sulpiride but not by SCH23390 was potentiated. It is concluded that chronic treatment of animals with Li2CO3 is able to alter D2 dopamine receptors reponse.
Structural Basis for Activation of G‐Protein‐Coupled Receptors
Authors: Gether Ulrik , Asmar Fazila , Meinild Anne Kristine , Rasmussen Søren G. F.
Published: March 2003

Abstract: Our understanding of how G‐protein‐coupled receptors (GPCRs) operate at the molecular level has been considerably improved over the last few years. The application of advanced biophysical techniques as well as the availability of high‐resolution structural information has allowed insight both into conformational changes accompanying GPCR activation and the underlying molecular mechanism governing transition of the receptor between its active and inactive states. Using the β2‐adrenergic receptor as a model system we have obtained evidence for an evolutionary conserved activation mechanism where disruption of intramolecular interactions between TM3 and TM6 leads to a major conformational change of TM6 relative to the rest of the receptor. This conclusion was based on experiments in which environmentally sensitive, sulfhydryl‐reactive fluorophores were site‐selectively incorporated into wild‐type and mutant β2‐adrenergic receptors purified from Sf‐9 insect cells. Our studies have also raised important questions regarding kinetics of receptors activation. These questions should be addressed in the future by application of techniques that will allow for simultaneous measurement of conformational changes and receptor activation. At the current stage we are exploring the possibility of reaching this goal by direct in situ labeling of the β2‐adrenergic receptor in Xenopus Laevis oocytes with conformationally sensitive fluorescent probes and parallel detection of receptor activation by co‐expression with the cAMP sensitive Cl− channel CFTR (cystic fibrosis transmembrane conductance regulator) and electrophysiological measurements.
What do young people think about the dangers of sunbathing, skin cancer and sunbeds? A questionnaire survey among Italians
Authors: Monfrecola G. , Fabbrocini G. , Posteraro G. , Pini D.
Published: March 2003

Previous experience in Australia and Sweden showed that public education programs produced substantial changes in people’s opinions, attitudes and perceptions about melanoma, non‐melanoma skin cancer, sunlight, sunbeds and suntanning. In order to organize effective prevention campaigns, more must be known about the sunbathing habits of children and adolescents. The aim of our study was to assess the knowledge that young people in a southern European country have about sun exposure. A total of 764 young people ranging from 16 to 22 years old (mean age: 19.3±1.2 years) responded to a questionnaire. Our study indicates that young people are very aware of the risks associated with sunbathing but that they continue to expose themselves without taking precautions. This suggests that: a) the majority of young Italians are reasonably well‐informed but they do not take preventative measures; b) one effective measure could be promotion of the idea that an untanned body is more esthetically pleasing than a tanned one; c) a crucial point in the programming of future safety measures in suntan centers involves rigorous and regular controls.
UVA protection efficacy of sunscreens can be determined by thepersistent pigment darkening (PPD) method
Authors: Moyal Dominique , Chardon Alain , Kollias Nikiforos
Published: March 2003

Background: The UVA‐induced Persistent Pigment Darkening (PPD) in vivo has been proposed as an end point for the evaluation of UVA protection.

Aims:

This study was designed to determine whether PPD can be used to correctly evaluate the in vivo effectiveness of UVA filters such as oxybenzone, avobenzone, ecamsule and zinc oxide concentrated and together with UVB filters.

Methods: The UVA protection effectiveness of a number of commercial sunscreen products with either SPF 15 or SPF 30 was determined.

Results: The UVA protection increased closely with the concentration of the UVA filters and was independent of UVB filters. The PPD method proved sensitive to all UVA filters irrespective of their range of absorbance within the UVA range.

Conclusion: The results show PPD to be a stable end point inducible by all the UVA wavelengths, not affected by fluence rate, i.e. a reliable endogenous UVA dosimeter in the skin.
Effect of UV irradiation on type I collagen fibril formation in neutral collagen solutions
Authors: Menter Julian M. , Patta Abrienne M. , Sayre Robert M. , Dowdy John , Willis Isaac
Published: March 2003

Background: Collagens have the well‐known ability to spontaneously self‐associate to form fibrils at physiological temperature and neutral pH in vitro and in vivo. Because solar UV may photochemically alter collagen, the kinetics of fibril formation may be modified. Thus, we have begun a systematic study of the effect of various UV wavebands on fibril formation.

Methods: Citrate‐soluble calf skin collagen (Elastin Products) was dissolved at 0.05% in 0.5 M HOAc, dialyzed over 2 days into two changes of 0.0327 M phosphate buffer, pH 7.0 at 4 °C, and centrifuged at 48 000×g. Photolysis was carried out at 4 °C with either (a) UVC (UVG–11 lamp), (b) filtered solar‐simulating radiation (SSR) or UVA (SSR or UVL–21 lamp filtered with a 2.0 mm Schott WG 345 filter). Gelation was commenced by rapidly raising the temperature from 8 °C to 33 °C. Nucleation and growth were followed by turbidimetric measurements at 400 nm.

Results: UVC radiation (0–17.3 J/cm2) resulted in a dose‐dependent decrease in the rate of fibril growth. Under these conditions, concomitant collagen cross‐linking and degradation occurred. Fibril nucleation, a prerequisite for growth, was rapid (threshold ∼ 2 min) and was not affected by UVC, UVA or SSR. SSR (0–1320 J/cm2) caused a small decrease in growth rate and in the degree of fibril formation. UVA radiation (0–1080 J/cm2) had a similar effect. “Direct” photochemical damage thus paralleled absorption via various collagen chromophores, with UVC>SSR∼UVA. The presence of riboflavin (RF) resulted in ground‐state interactions that markedly altered both nucleation and growth kinetics. Irradiation with 29.6 J/cm2 UVA in the presence of RF photosensitizer caused relatively minor additional changes in fibrillation kinetics.

Conclusions: These results collectively indicate that fibril formation is markedly dependent on specific ground state interactions and relatively insensitive to nonspecific UV damage. On the other hand, fibrils thus formed from photochemically altered collagen may have altered structural properties that could have subtle but unfavorable effects on the local dermal milieu in vivo. Notwithstanding, the relative insensitivity of fibrillogenesis to non‐specific photochemical damage probably represents a favorable adaptation, overall, which tends to conserve the mechanical integrity of the skin.
In vitro melatonin treatment enhances splenocyte proliferation in prairie voles
Authors: Drazen Deborah L. , Klein Sabra L. , Yellon Steven M. , Nelson Randy J.
Published: March 2003

The seasonal effects of photoperiod on reproduction are mediated by melatonin, and it is hypothesized that increased immune function in short days is due to the increase in the duration of nightly melatonin secretion. Melatonin can act both directly and indirectly on target tissue within the immune system. The present study sought to tease apart the direct and indirect effects of melatonin on one aspect of immune function by examining the influence of in vitro melatonin on splenocyte proliferation in female prairie voles held in long (LD 16:8) or short (LD 8:16) days. Splenocyte proliferation in response to the T‐cell mitogen concanavalin A was enhanced by the addition of melatonin in vitro, as compared to cultures receiving no melatonin. Body mass increased in short‐day housed prairie voles, indicating that the animals were responsive to photoperiod. However, photoperiod did not affect splenocyte proliferation in the present study. These results support the hypothesis that melatonin exerts a direct effect on splenocyte proliferation, potentially via high‐affinity melatonin receptors localized on splenocytes. The findings also indicate that, irrespective of photoperiod, melatonin exerts direct effects on splenocytes to enhance immune function.
Circadian urinary 6‐sulphatoxymelatonin, cortisol excretion and locomotor activity in airline pilots during transmeridian flights
Authors: Tresguerres Jesús A.F. , Ariznavarreta Carmen , Granados Blanca , Martín Mercedes , Villanúa María A. , Golombek Diego A. , Cardinali Daniel P.
Published: March 2003

Airline pilots divided into two groups of age (over and under 50 years) were studied before, during and after westbound (Madrid–Mexico City–Madrid, n=12) and eastbound (Madrid–Tokyo–Madrid, n=21) flights. A group of 10 age‐matched people staying in Madrid were submitted to the same tests and served as a control group. Changes in urinary 6‐sulphatoxymelatonin (6‐aMTs) and free cortisol excretion (determined in 6‐hr intervals) were measured by radioimmunoassay. Using wrist actigraphy, the circadian locomotor activity rhythm (LAR) was also monitored. Maximal baseline excretion of 6‐aMTs occurred between 00:00 and 12:00 hr and maximal excretion of cortisol took place between 6:00 and 12:00 hr in the control group. Analysed globally, older pilots exhibited significantly lower values of 6‐aMTs than younger ones. In both flight directions, pilots maintained the pattern of excretion of 6‐aMTs, corresponding to baseline. The return flight to Madrid from Mexico and Tokyo coincided with a maximum in 6‐aMTs excretion. Pilots kept the cortisol pattern found in the control group, with those over 50 years of age exhibiting significantly lower cortisol values than the younger ones. A 7‐hr delay in acrophase of LAR after 2 days in Mexico City was found after cosinor analysis, and similar pre‐flight values were found after returning to Madrid. An 8–9‐hr acrophase advance of LAR was observed after arriving in Tokyo, with acrophase on the post‐return flight day still being advanced 3–4 hr as compared to pre‐flight values. Decreases in the amplitude of LAR in older pilots were found at Mexico City, as well as at Tokyo stopover and on post‐flight day. Data confirm the occurrence of internal desynchronization in airline crewmembers after transmeridian flights.
Seasonal variations of in vivo and in vitro melatonin production in a passeriform bird, the house sparrow (Passer domesticus)
Authors: Brandstätter Roland , Kumar Vinod , Van'T Hof Thomas J. , Gwinner Eberhard
Published: March 2003

Melatonin, released from the pineal gland, is an important signal within the circadian pacemaking system of passeriform birds. Until now, seasonal variations in melatonin production have only been examined in a few avian species and the role of melatonin in the regulation of annual rhythms in birds is unclear. We investigated plasma melatonin in a group of house sparrows kept in an outside aviary in spring (March/April), summer (May/June), autumn (September/October), and winter (December/January). The durations of elevated melatonin values mirrored the seasonal changes in night length to a certain degree, the melatonin signal being longest in winter and shortest in summer. Additionally, plasma melatonin peak amplitudes differed significantly among seasons, with highest values in spring and summer and lowest values in winter. Cultured explanted pineal glands obtained from animals in winter and summer showed patterns of in vitro melatonin release comparable to in vivo circulating melatonin with different durations of elevated melatonin and peak amplitude values. These data indicate that the circadian pacemaking system of the house sparrow changes properties seasonally, either as a result of endogenous mechanisms or in response to environmental conditions. These properties are maintained in the pineal gland even after isolation from the animal.
Increased levels of malondialdehyde and nitrite/nitrate in the blood of asphyxiated newborns: reduction by melatonin
Authors: Fulia Francesco , Gitto Eloisa , Cuzzocrea Salvatore , Reiter Russel J. , Dugo Laura , Gitto Placido , Barberi Salvatore , Cordaro Stefania , Barberi Ignazio
Published: March 2003

Free radicals have been implicated in the pathogenesis of neonatal asphyxia and its complications. This study measured a product of lipid peroxidation, malondialdehyde, and the nitrite/nitrate levels in the serum of 20 asphyxiated newborns before and after treatment with the antioxidant melatonin given within the first 6 hr of life. Ten asphyxiated newborns received a total of 80 mg of melatonin (8 doses of 10 mg each separated by 2‐hr intervals) orally. One blood sample was collected before melatonin administration and two additional blood samples (at 12 and 24 hr) were collected after giving melatonin. A third group of healthy newborn children served as controls. Serum malondialdehyde and nitrite+nitrate concentrations in newborns with asphyxia before treatment were significantly higher than those in infants without asphyxia. In the asphyxiated newborns given melatonin, there were significant reductions in malondialdehyde and nitrite/nitrate levels at both 12 and 24 hr. Three of the 10 asphyxiated children not given melatonin died within 72 hr after birth; none of the 10 asphyxiated newborns given melatonin died. The results indicate that the melatonin may be beneficial in the treatment of newborn infants with asphyxia. The protective actions of melatonin in this study may relate to the antioxidant properties of the indole as well as to the ability of melatonin to increase the efficiency of mitochondrial electron transport.
The identification of the UV degradants of melatonin and their ability to scavenge free radicals
Authors: Maharaj Deepa S. , Anoopkumar‐Dukie Shailendra , Glass Beverley D. , Antunes Edith M. , Lack Barbara , Walker Roderick B. , Daya Santy
Published: March 2003

Ultraviolet (UV) light is known to induce the generation of free radicals in biological tissues such as skin. Of these free radicals, the O2–· and particularly the ·OH radical can induce cellular damage including lipid peroxidation. Thus, the use of antioxidants to prevent such damage induced by UV irradiation has received much attention recently. One such antioxidant, which has the potential to be incorporated into sunscreens, is the pineal secretory product melatonin. One of the concerns of using melatonin in sunscreens is its photostability. In the present study, we investigated the photostability of melatonin subjected to UV irradiation. In addition, we used liquid chromatography mass spectrometry (LC‐MS) to identify the degradants and we also assessed the ability of the degradants to inhibit O2–· generation as well as lipid peroxidation in rat brain homogenate. The results show that UV irradiation of melatonin (0.1 mg/mL) using a 400‐W lamp for 2 hr caused a significant decline of melatonin to 18% of its original concentration after 20 min, with the decline continuing until the melatonin concentration reaches zero at 120 min. The LC‐MS results show that the degradants of melatonin are 6‐hydroxymelatonin and N1‐acetyl‐N2‐formyl‐5‐methoxykynurenamine (AFMK). These degradants were able to provide equipotent activity against potassium cyanide (KCN)‐induced superoxide generation compared to non‐irradiated melatonin. Thus, the study shows that although melatonin is rapidly degraded by UV irradiation, the degradants retain antioxidant activity, making melatonin a likely candidate for inclusion in sunscreens.
Transformation of barbituric acid into alloxan by hydroxyl radicals: interaction with melatonin and with other hydroxyl radical scavengers
Authors: Brömme H. J. , Mörke W. , Peschke E.
Published: March 2003

Abstract: Barbituric acid (2,4,6‐pyrimidinetrione) can be transformed by a non‐enzymatic hydroxylation into alloxan (2,4,5,6‐pyrimidinetetrone). This transformation can be used as a reaction indicating the formation of hydroxyl radicals (·OH). This conversion was detected using HPLC. Formation of ·OH was demonstrated by electron spin resonance (ESR) spectroscopy combined with spin‐trapping techniques. It was shown that ·OH generated via the Fenton reaction abstracts first a hydrogen atom from barbituric acid (BA) and forms intermediately a paramagnetic derivative of BA. After a second attack by another ·OH, the BA radical is transformed into dialuric acid (DA), which autoxidizes via the alloxan radical (·ALX) to ALX. Superoxide radicals (·O2−) are formed during autoxidation of DA and ·ALX. They are able to regenerate ferrous ions. As a result, traces of iron salts are capable of catalyzing the conversion of large amounts of BA into ALX. Several scavengers of ·OH were tested with regard to their efficiency in preventing the transformation of BA into ALX. Of all the scavengers analyzed, melatonin was shown to be one of the most potent compounds.