bluuebunny/crossref_metadata_2025 huggingface dataset:
Enzymatic and Non‐Enzymatic Oxygenation of Tyrosine
Authors: WITTBJER ANNA , ODH GERD , ROSENGREN EVALD , RORSMAN HANS
Published: July 2006

Tyrosinase isolated from cultured human melanoma cells was studied for tyrosine oxygenation activity. l‐Tyrosine and d‐tyrosine were used as substrates and dopa was measured with HPLC and electrochemical detection as the product of oxygenation. Incubations were performed in the presence or absence of dopamine as co‐substrate. Oxygenation of l‐tyrosine occurred only in the presence of dopamine as co‐substrate. No oxygenation of d‐tyrosine was found, and we conclude that human tyrosinase is characterised by exclusive specificity for the l‐isomer of tyrosine in its oxygenase function. It has recently been suggested that superoxide anion is a preferential oxygen substrate for human tyrosinase. Incubations were therefore performed with l‐ and d‐tyrosine, human tyrosinase, and xanthine/xanthine oxidase in the system, generating superoxide anion and hydrogen peroxide. Considerable formation of dopa was observed, but the quantity was the same irrespective of whether d‐tyrosine or l‐tyrosine was used as the substrate. Furthermore, formation of dopa occurred in a xanthine/xanthine oxidase system when bovine serum albumin (BSA) was substituted for tyrosinase. Our results provide no evidence that superoxide anion is an oxygen substrate for human tyrosinase. In the incubate containing xanthine/xanthine oxidase, catalase completely inhibited dopa formation, and superoxide dismutase and mannitol each strongly inhibited dopa formation. The results are compatible with hydroxyl radicals being responsible for the formation of dopa, since such radicals may be secondarily formed in the presence of superoxide anion and hydrogen peroxide.
The Administration of an α‐MSH Analogue Reduces the Serum Release of IL‐1α and TNFα Induced by the Injection of a Sublethal Dose of Lipopolysaccharides in the BALB/c Mouse
Authors: GONINDARD CHRISTOPHE , GOIGOUX CATHERINE , HOLLANDE ETIENNE , D'HINTERLAND LUCIEN DUSSOURD
Published: July 2006

The injection of α‐MSH or of one of its analogues ([Nle4‐D.Phe7] α‐MSH4–10) reduced, in vivo, the release of two cytokines (IL‐1α and TNFα) involved in inflammation. The inflammatory state was induced in BALB/c mice by intraperitoneal injection of a sublethal dose of lipopolysaccharides (LPS). The assay of these cytokines by ELISA showed a reduction of 20% with α‐MSH and between 30 and 60% with the α‐MSH analogue. The α‐MSH or the analogue was administered in one of two ways: intravenously or subcutaneously. The most efficient method seemed to be the subcutaneous one because it improved the activity 10,000 times more than the intravenous method. Moreover, the analogue induced a regression of mortality in the animals treated by the intravenous method. Our results show that α‐MSH and one of its analogues inhibit IL‐1α and TNFα, and can be used as anti‐inflammatory molecules.
Effect of Pituitary and Ovarian Hormones on Human Melanocytes In Vitro
Authors: MAEDA KAZUHISA , NAGANUMA MASAKO , FUKUDA MINORU , MATSUNAGA JUN , TOMITA YASUSHI
Published: July 2006

Normal human melanocytes in culture became enlarged and dendritic after a 2‐day incubation with either the pituitary (β‐MSH, a potent analog of α‐MSH, ACTH, FSH and LH) or the ovarian (estradiol, estriol and progesterone) hormones. Under the same experimental conditions, pituitary hormones also increased both the tyrosinase activity and tyrosinase‐related protein‐1 (TRP‐1) while ovarian hormones increased TRP‐1 but not tyrosinase activity. The results suggest that pituitary and ovarian hormones possibly induce hyperpigmentation of the skin by stimulating the melanogenesis in epidermal melanocytes, and that estradiol and progesterone may be involved in the pathogenesis of melasma (chloasma) usually developing between early adulthood and menopause in which a high concentration of serum ovarian hormones was maintained.
Spectrophotometric Characterization of Eumelanin and Pheomelanin in Hair
Authors: OZEKI HIROYUKI , ITO SHOSUKE , WAKAMATSU KAZUMASA , THODY ANTHONY J.
Published: July 2006

Mammalian melanins exist in two chemically distinct forms: the brown to black eumelanins and the yellow to reddish‐brown pheomelanins. They can be quantified by HPLC analysis of pyrrole‐2,3,5‐tricarboxylic acid (PTCA) and aminohydroxyphenylalanine (AHP). We recently developed a spectrophotometric method for assaying the total amount of eu‐ and pheomelanins by dissolving melanins in Soluene‐350 plus water. In this study, we examined whether absorbance at 500 nm (A500) of the Soluene‐350 solution reflects the total amount of melanins obtained by the HPLC methods, and whether the ratio of absorbances between 650 and 500 nm reflects the eumelanin/total melanin ratio in mouse hair, sheep wool, and human hair. Our findings were as follows: (1) Total melanin levels calculated from A500 values correlate well with those obtained from PTCA and AHP values by multiplying with the following factors: for mice, PTCA × 45 + AHP × 2.5; for sheep, PTCA × 40 + AHP × 15; and for humans, PTCA × 160 + AHP × 10. (2) The A650/A500 ratios were higher (0.25–0.33) in black to brown hair while they were significantly lower (0.10–0.14) in yellow to red hair. These results indicate that (1) the A500 value can be used to quantify the total combined amount of eu‐ and pheomelanins, and (2) the A650/A500 ratio can serve as a parameter to estimate the eumelanin/total melanin ratio. The present method provides a convenient way to qualitatively characterize eu‐ and pheomelanins in melanins produced in follicular melanocytes.
Detection of Mouse Tyrosinase With a Monoclonal Antibody MAT‐1 Against Human Tyrosinase
Authors: SUZUKI SATOSHI , TAKIMOTO HIROYUKI , MASUI SHIGEKI , KATO TOMOMI , SHIBATA KOUSHI , TOMITA YASUSHI , SHIBAHARA SHIGEKI , NAKANO HIROYUKI
Published: July 2006

In this study we explored the possible application of MAT‐1, which has been established as a monoclonal antibody against human tyrosinase, for detection of mouse tyrosinase. The MAT‐1 reacted with B16 mouse melanoma cells, but not with tyrosinase‐negative NIH‐3T3 mouse fibroblasts. In western blot analysis of the large granule fraction (LGF) of B16 cells, MAT‐1 detected a single protein of 80 kDa, whose size was close to that of human tyrosinase detected with MAT‐1 in extracts of human melanocytes. Furthermore, the 80 kDa band that was detected with MAT‐1 in the LGF of B16 cells was also detected by DOPA reaction. In order to confirm that the protein detected with MAT‐1 is tyrosinase, a transient expression assay was carried out. When mouse tyrosinase or mouse tyrosinase‐related protein 1, which shares high homology with human tyrosinase, was transiently expressed in tyrosinase‐negative K1735 mouse melanoma cells by cDNA transfection, MAT‐1 reacted only with the cells expressing mouse tyrosinase. These results indicate that MAT‐1 specifically reacts with mouse tyrosinase.
Azelaic Acid Has Sensitizing Effect in the Chemotherapeutic Treatment of Several Melanoma Cell Lines
Authors: RODRIGUEZ‐VICENTE J , VICENTE‐ORTEGA V. , CANTERAS‐JORDANA
Published: July 2006

Chemotherapy for melanoma results in low response and must be reinforced with sensitizer compounds. We believed that azelaic acid (AZA) could modulate melanomas’resistance to antineoplastics. Therefore we tried to compare in vitro treatment with antineoplastics alone versus AZA treatment followed by antineoplastics. We carried out MTT assays to evaluate the cytotoxicity of melphalan, lomustine (CCNU), fotemustine, and 4‐Hydroxyanisole (4‐HA) on three melanoma lines (B16F10, SK‐MEL‐28, and SK‐MEL‐1), and the modulating effect of pretreatment with AZA (1 mM). AZA showed a dose‐dependent antineoplastic activity on the three lines. Melphalan was the most active drug followed by CCNU, fotemustine, and 4‐HA. The most sensitive line was B16F10 and the least sensitive was SK‐MEL‐1. Previous treatment with AZA of B16F10 reinforced the effect of melphalan (2.5 times), CCNU (10 times), and fotemustine (14 times); whereas for SK‐MEL‐28 and SK‐MEL‐1, only the cytotoxicity of CCNU and fotemustine increased. An antagonist effect was produced by 4‐HA on all three lines. We concluded that AZA enhances in vitro cytotoxicity of CCNU and fotemustine.
The Effect of Ultraviolet B Induced Adult T Cell Leukemia‐Derived Factor/Thioredoxin (ADF/TRX) on Survival and Growth of Human Melanocytes
Authors: FUNASAKA YOKO , ICHIHASHI MASAMITSU
Published: July 2006

Ultraviolet B (UVB) radiation is known to induce reactive oxygen species (ROS) in the skin. The skin, however, counteracts ROS by both constitutional and newly produced antioxidants. One such antioxidant, adult T cell leukemia‐derived factor (ADF), a human homologue of thioredoxin (TRX), was shown to be efficiently produced in and released from cultured normal human keratinocytes after UVB irradiation by Northern and Western blot analyses and enzyme‐linked immunoabsorbent assay (ELISA). Recombinant ADF (rADF) did not rescue UVB‐induced melanocyte death, either when added pre‐ or post‐UV irradiation. However, further addition of neutralizing antibody caused cell death of both keratinocytes and melanocytes. rADF was shown to induce higher expression in melanocortin‐1 receptor (MC1‐R) mRNA accompanied by increased binding activity using 125I labeled [Nle4, D‐Phe7]‐α‐MSH in melanocytes, leading to the enhanced increment of DNA synthesis.

Taken together, it was shown that released ADF from UVB‐irradiated keratinocytes acts as a survival factor for both keratinocytes and melanocytes but does not rescue UV‐induced melanocyte death. Further, it may work as one of the stimulatory factors for UVB‐induced melanogenesis by upregulating MSH‐R binding activity in combination with the enhanced DNA synthesis by α‐MSH.
Luminol‐Enhanced Chemiluminescent Response of Human Melanocytes and Melanoma Cells to Hydrogen Peroxide Stress
Authors: MEYSKENS FRANK L. , VAN CHAU HUNG , TOHIDIAN NILOU , BUCKMEIER JULIE
Published: July 2006

The response of human melanocytes and melanoma cells to hydrogen peroxide stress was measured. Cells were exposed to glucose/glucose oxidase or free H2O2 and reactive oxygen species measured by luminol‐enhanced chemiluminescence. The response was distinctly different between the two types and the addition of superoxide dismutase to melanoma cells paradoxically enhanced the chemiluminescent signal. These findings coupled with other known differences between the way these two types of cells handle oxidative stress at a molecular level suggests that a therapeutic window may be avail‐able for exploitation.
Modeling Drug‐Melanin Interaction With Theoretical Linear Solvation Energy Relationships
Authors: LOWREY ALFRED H. , FAMEINI GEORGE R. , LOUMBEV VALERY , WILSON LELAND Y. , TOSK JEFFREY M.
Published: July 2006

The affinity of drugs and other xenobiotic agents for melanin is a well‐known phenomenon, often occurring with serious physiological consequences. For example, the interaction of anti‐psychotic drugs with neuromelanin may play a pivotal role in the induction of extrapyramidal movement disorders associated with the chronic administration of phenothiazine and other neuroleptic agents. Little, however, is known about the complete nature of melanin‐drug binding and the impact of these interactions on the physicochemical properties of melanin.

Data, such as binding affinities, can be analyzed using recently developed computational methods that combine mathematical models of chemical structure with statistical analysis. In particular, theoretical linear solvation energy relationships provide a convenient model for understanding and predicting biological, chemical, and physical properties.

By using this modeling technique, drug‐melanin binding of a set of 16 compounds has been analyzed with correlation analysis and a set of theoretical molecular parameters in order to better understand and characterize drug‐melanin interactions. The resulting correlation equation supports a charge transfer model for drug‐melanin complex formation and can also be used to estimate binding constants for related compounds.
Agouti Protein Inhibits the Production of Eumelanin and Phaeomelanin in the Presence and Absence of α‐Melanocyte Stimulating Hormone
Authors: GRAHAM ALISON , WAKAMATSU KAZUMASA , HUNT GILLIAN , ITO SHOSUKE , THODY ANTHONY J.
Published: July 2006

Melanocytes synthesise two types of melanin: the brown‐black eumelanin and the red‐yellow phaeomelanin. In mice, the relative proportions of these two melanins are regulated by α‐MSH, which preferentially increases the synthesis of eumelanin and by the Agouti protein (AP), the expression of which correlates with the growth of yellow phaeomelanin‐containing hair. It has been proposed that AP acts by antagonizing the action of α‐MSH at the MCI receptor, although it has been suggested that it may also act independently of α‐MSH. In the present study we show that AP inhibits melanogenesis in B16F1 melanoma cells in the presence and absence of α‐MSH and also causes dose‐related decreases in the synthesis of both eumelanin and phaeomelanin. In the presence of α‐MSH AP had a greater effect on eumelanin production and this is consistent with an antagonistic action at the MCI receptor. In the absence of α‐MSH however, AP produced similar reductions in the synthesis of both melanins. These changes were not seen in B16G4F cells which lack the MCI receptor, suggesting that even in the absence of α‐MSH AP acts at the MCI receptor. How this action is mediated at the intracellular level is not yet clear, although it appears to be associated with a decrease in tyrosinase activity.
Establishment of a Murine Model for Metastasis of Cytokine‐Producing Tumor to the Brain
Authors: NAKAI MASAMICHI , TAKAUCHI SHIGERU , YAMAGUCHI TOORU , KAWAMATA TOSHIO , MAEDA KIYOSHI , TANAKA CHIKAKO
Published: July 2006

The A375 cell line, derived from human malignant melanoma, has characteristics of interleukin‐6 (IL‐6) production. By using this cell line, we have investigated a murine metastasis model of IL‐6‐producing tumors to the brain by injecting A375 cells directly into the left cardiac ventricle. Nude mice were anesthetized with intraperitoneal injection of pentobarbital sodium. Next, A375 cells suspended in phosphate‐buffered saline (PBS) were injected into the left cardiac ventricle of mice. An intracardiac injection of 105 cells developed tumor colonies in the brain after 4 to 6 weeks. Metastatic cells were found in every lobe of the brain. An immunocytochemical study revealed IL‐6 production by A375 cells at the metastatic sites in the brain. By the transfection of genes encoding proteins into A375 cells, a novel model of protein expression in the brain in vivo could be constructed. Our system does not require great skill. Our experimental model will facilitate future studies of the local effects of proteins in the brain.
The Erythrophore in the Larval and Adult Dorsal Skin of the Brown Frog, Rana ornativentris: Its Differentiation, Migration, and Pigmentary Organelle Formation
Authors: ICHIKAWA YOUKO , OHTANI HIROMI , MIURA IKUO
Published: July 2006

To determine whether or not the erythrophore originates from xanthophores in the dorsal skin of the brown frog, Rana ornativentris, we morphologically examined the differentiation and migration of the two chromatophore types and their pigmentary organelle formation. At an early tadpole stage, three kinds of chromatophores, xanthophores, iridophores, and melanophores, appeared in the subdermis, whereas the erythrophore did so just before the foreleg protrusion stage. By the middle of metamorphosis, most chromatophores other than erythrophores had migrated to the subepidermal space. Erythrophores, which appeared late in the subdermis, proliferated actively there during metamorphosis and finished moving into the subepidermal space by the completion of metamorphosis. Carotenoid vesicles and pterinosomes within the erythrophores and xanthophores showed several significant differences in structure. In xanthophores, carotenoid vesicles were abundant throughout life, whereas those in erythrophores decreased in number with the growth of the frogs. The fibrous materials contained in the pterinosomes were initially scattered but soon formed a concentric lamellar structure. In erythrophores, the lamellar structure began to form at the periphery of the organelles but at the center in xanthophores. In addition, the pterinosomes of erythrophores were uniform in size throughout development, while those of xanthophores showed a tendency to become smaller after metamorphosis. The pterinosomes of xanthophores were significantly larger than those of erythrophores. These findings suggest that an erythrophore is not a transformed xanthophore, although they resemble each other closely in many respects.
The Inhibitory Effect of Glabridin from Licorice Extracts on Melanogenesis and Inflammation
Authors: YOKOTA TOMOHIRO , NISHIO HIROYUKI , KUBOTA YASUO , MIZOGUCHI MASAKO
Published: July 2006

Glabridin is the main ingredient in hydrophobia fraction of licorice extract affecting on skins. In this study, we investigated inhibitory effects of glabridin on melanogenesis and inflammation using cultured B16 murine melanoma cells and guinea pig skins. The results indicated that glabridin inhibits tyrosinase activity of these cells at concentrations of 0.1 to 1.0 μg/ml and had no detectable effect on their DNA synthesis. Combined analysis of SDS‐polyacrylamide gel electrophoresis and DOPA staining on the large granule fraction of these cells disclosed that glabridin decreased specifically the activities of Tl and T3 tyrosinase isozymes.

It was also shown that UVB‐induced pigmentation and erythema in the skins of guinea pigs were inhibited by topical applications of 0.5% glabridin. Anti‐inflammatory effects of glabridin in vitro were also shown by its inhibition of superoxide anion productions and cyclooxygenase activities. These data indicated that glabridin is a unique compound possessing more than one function; not only the inhibition of melanogenesis but also the inhibition of inflammation in the skins.

By replacing each of hydroxyl groups of glabridin with others, it was revealed that the inhibitory effect of 2′‐O‐ethyl glabridin was significantly stronger than that of 4′‐O‐ethyl‐glabridin on melanin synthesis in cultured B16 cells at the concentration of 1.0 mg/inl. With replacement of both of two hydroxyl groups, the inhibitory effect was totally lost. Based on these data, we concluded that two hydroxyl groups of glabridin are important for the inhibition of melanin synthesis and that the hydroxyl group at the 4’ position of this compound is more closely related to melanin synthesis.
Mouse Models of Hermansky Pudlak Syndrome: A Review
Authors: SWANK RICHARD T. , NOVAK EDWARD K. , McGARRY MICHAEL P. , RUSINIAK MICHAEL E. , FENG LIJUN
Published: July 2006

Hermansky Pudlak Syndrome (HPS) is a recessively inherited disease affecting the contents and/or the secretion of several related subcellular organelles including melanosomes, lysosomes, and platelet dense granules. It presents with disorders of pigmentation, prolonged bleeding, and ceroid deposition, often accompanied by severe fibrotic lung disease and colitis. In the mouse, the disorder is clearly multigenic, caused by at least 14 distinct mutations. Studies on the mouse mutants have defined the granule abnormalities of HPS and have shown that the disease is associated with a surprising variety of phenotypes affecting many tissues. This is an exciting time in HPS research because of the recent molecular identification of the gene causing a major form of human HPS and the expected identifications of several mouse HPS genes. Identifications of mouse HPS genes are expected to increase our understanding of intracellular vesicle trafficking, lead to discovery of new human HPS genes, and suggest diagnostic and therapeutic approaches toward the more severe clinical consequences of the disease.
Dermatoscopy and High Frequency Sonography: Two Useful Non‐Invasive Methods to Increase Preoperative Diagnostic Accuracy in Pigmented Skin Lesions
Authors: KRÄHN GERTRAUD , GOTTLÖBER PETRA , SANDER CHRISTIAN , PETER RALF U.
Published: July 2006

Dermatoscopy and high frequency sonography have recently been combined to increase diagnostic preoperative accuracy in the treatment of pigmented skin lesions. In this monocentric study 80 patients with pigmented skin lesions were evaluated clinically, by dermatoscopy, and 20 MHz‐sonography followed by dermatohistopathological evaluation; 39 malignant melanomas, 37 common nevi, 3 dysplastic nevi, and 1 nevus Spitz were diagnosed histologically. In 72 of the 80 cases (91.3%) dermatoscopical diagnoses were confirmed by histopathology, compared to only 79% correct clinical diagnoses. For the mere clinical diagnosis of melanoma sensitivity was 79%, specificity was 78% and diagnostic accuracy was 65%. All diagnostic values increased by dermatoscopy: sensitivity reached 90%, specificity was 93%, and diagnostic accuracy was 83%.

In order to determine tumor thickness preoperatively tumor thickness was measured by 20 MHz sonography. The correlation of tumor thickness between histometric and sonographic results was determined for nevi (r = 0.93) and melanoma (r = 0.95); 74.3% of melanomas were diagnosed correctly within an 0.2 mm range. Regarding the clinical important limit of 1 mm tumor thickness, 87.2% were diagnosed in accordance with histometric evaluation.

An increase of 18% in diagnostic accuracy by dermatoscopy and 87.2% of correctly diagnosed cases of tumor thickness of malignant melanoma by high frequency sonography clearly demonstrate that these methods should be considered standard procedures in the diagnosis of pigmented skin lesions and will facilitate the decision on necessary surgical treatment.
Development of Melanocyte Progenitors in Murine Steel Mutant Neural Crest Explants Cultured With Stem Cell Factor, Endothelin‐3, or TPA
Authors: ONO HIROTAKE , KAWA YOKO , SANO MARIA , ITO MASARU , TAKANO ATSUKO , KUBOTA YASUO , MATSUMOTO JIRO , MIZOGUCHI MASAKO
Published: July 2006

Stem cell factor (SCF) has been suggested to be indispensable for the development of neural crest cells into melanocytes because Steel mutant mice (i.e., Sl/Sf1) have no pig‐mented hairs. On the other hand, it has been demonstrated that the addition of endothelin 3 (ET‐3) or TPA to neural crest cell cultures can induce melanocyte differentiation without addition of extrinsic SCF. In this study, we excluded the influence of intrinsic SCF by using SI/SI mouse embryos to study more precisely the effects of natural cytokines, such as extrinsic soluble SCF or ET‐3, or chemical reagents, such as TPA or cholera toxin. We found that SCF is supplied within the wild‐type neural crest explants and that ET‐3 cannot induce melanocyte differentiation or proliferation without SCF. These results indicate that SCF plays a critical role in survival or G1/S entry of melanocyte progenitors and that SCF initially stimulates their proliferation and then ET‐3 accelerates their proliferation and differentiation. TPA has the ability to elicit neural crest cell differentiation into melanocytes without exogenously added SCF but it is not as effective as SCF because many more melanocytes developed in the wild‐type neural crest explants cultured with TPA.
A Comparative Study of the Effect of Pigment on Drug Toxicity in Human Choroidal Melanocytes and Retinal Pigment Epithelial Cells
Authors: EVES PAULA , SMITH‐THOMAS LINDA , HEDLEY SUSAN , WAGNER MARK , BALAFA CHARIKLIA , NEIL SHEILA MAC
Published: July 2006

The aim of this study was to investigate whether the presence of pigment affects the sensitivity of pigmented cells of the eye, retinal pigment epithelium (RPE) and choroidal melanocytes (CMs) to the cyto‐toxic effects of xenobiotic drugs.

Two approaches were used to compare pigmented versus unpigmented cells: RPE cells were repigmented by phagocytosis of synthetic melanin; UVB irradiation was used to induce an increase in pigment in both RPE and CMs. Three drugs known to induce toxicity in the eye, tamoxifen, chloroquine and thioridazine, were used to assess the sensitivity of cells to xenobiotic drugs.

RPE cells were more resistant than CMs to the cytotoxic effects of all three drugs by a factor of 5‐fold for tamoxifen, 7‐fold for thioridazine and 30‐fold for chloroquine. When RPE cells were repigmented using synthetic melanin, their sensitivity to tamoxifen was unchanged, they showed a slightly improved response to thioridazine (after 3 days of incubation with this drug), but they showed greatly increased toxicity to chloroquine (after 1 and 3 days of exposure to the drug), suggesting accumulation of this latter drug on the synthetic melanin.

UVB irradiation was used to achieve an increase in the pigment content of both RPE and CMs. CMs were much more sensitive to UVB than RPE cells. CMs appeared to synthesise pigment via DOPA oxidase activity; RPE cells showed an increase in fluorescent material independent of any detectable DOPA oxidase activity. Irrespective of the nature of the pigment that UVB induced in melanocytes and RPE cells, their subsequent response to thioridazine and chloroquine was unchanged by the presence of this pigment.
Genetic and Epigenetic Control of the Proliferation and Differentiation of Mouse Epidermal Melanocytes in Culture
Authors: HIROBE TOMOHISA , ABE HIROYUKI
Published: July 2006

Serum‐free culture of epidermal cell suspensions from neonatal skin of mice of strain C57BL/10JHir (B10) showed that α‐melanocyte‐stimulating hormone (α‐MSH) was involved in regulating the differentiation of melanocytes by inducing tyrosinase activity, melanosome formation, and dendritogenesis. Dibutyryl adenosine 3′:5′‐cyclic monophosphate (DB‐cAMP) similarly induced the differentiation of melanocytes. On the other hand, DBcAMP induced the proliferation of epidermal melanocytes in culture in the presence of keratinocytes. Basic fibroblast growth factor (bFGF) was also shown to stimulate the sustained proliferation of undifferentiated melanoblasts in the presence of DBcAMP and keratinocytes. These results suggest that the proliferation and differentiation of mouse epidermal melanoblasts and melanocytes in culture are regulated by the three factors; namely, cAMP, bFGF, and keratinocyte‐derived factors. Moreover, serum‐free primary culture of mouse epidermal melanocytes derived from B10 congenic mice, which carry various coat color genes, showed that the coat color genes were involved in regulating the proliferation and differentiation of mouse epidermal melanocytes by controlling the proliferative rate, melanosome formation and maturation, and melanosome distribution.
Horizontal and Vertical Pigment Spread into Surrounding Piebald Epidermis and Hair Follicles after Suction Blister Epidermal Grafting
Authors: HORIKAWA TATSUYA , MISHIMA YUTAKA , NISHINO KEISUKE , ICHIHASHI MASAMITSU
Published: July 2006

Following the earlier description of Carnot and Deflandre in 1896, pigment spread phenomenon in mammals was investigated using immunogenetically marked melanocytes (Billingham and Silver, Quart. Rev. Biol. 1960 35: 1–40; Billingham and Silver, Ann. N.Y. Acad. Sci. 1963 100: 348–363). In spite of a number of similar studies on vitiligo lesions, detailed evaluation of pigment spread in piebald lesions has not been reported. To gain further insight into the pigment spread phenomenon in human skin, five piebald patients were studied, on whom suction blister epidermal grafting therapy onto piebald patches was performed. In the present study, pigmentation of all epidermal grafts from normally pigmented areas spread horizontally. It was also found that pre‐existing white hairs in recipient sites became pigmented within 1 year after epidermal grafting. Immunofluorescence studies using melanocyte‐specific antibody NKI/beteb revealed the newly induced presence of melanocytes in the newly pigmented hair follicles. Further, to study the possible mechanisms inhibiting melanocyte migration from normal skin into piebald lesions, epidermis was grafted from border zones (containing both normal and piebald skin) into the center of hypopigmented lesions. Melanocytes clearly migrated through the border zone of grafted epidermis into surrounding recipient hypopigmented sites.
The Effect of Temperature on the Light‐Induced Pigment Movement in Fish Corneal Chromatophores
Authors: KONDRASHEV SERGEI L. , GNYUBKIN VICTOR F.
Published: July 2006

Corneal chromatophores of unusual morphology were used for studies on the influence of temperature on the intracellular pigment movement in two species of marine fish from different temperature zones: the tropical puffer, Canthigaster cinctus, and boreal whitespotted greenling, Hexagrammos stelleri. It was shown that both dispersion under bright illumination and aggregation at darkening are slower or decrease at lower temperatures when examined in the range of 12–27°C. The mean speed of the pigment translocations in the individual cell process was 0.38 μm/s at the highest temperature examined, with a range of 0.17–1.0 μm/s. Near the middle of the temperature range, the dynamic characteristics of cell pigment movement in tropical and boreal species were rather close, suggesting that there would be little divergent adaptations with respect to the mechanisms of the pigment transport. Corneal chromatophores are considered as a new promising model for cell motility studies.
Effects of 4‐Tertiary Butylphenol on the Tyrosinase Activity in Human Melanocytes
Authors: YANG FAN , BOISSY RAYMOND E.
Published: July 2006

Vitiligo is a common dermatological disorder characterized by the development of complete pigment loss from focal lesions that tends to increase in size over time. The etiology of vitiligo, resulting in the disappearance of functional melanocytes from involved skin, is not clearly understood. As a consequence, no satisfactory therapy has been developed. A subtype of vitiligo, termed‘occupational’or‘contact’vitiligo, is increased in individuals who are exposed to materials containing phenolic derivatives, such as 4‐tertiary butylphenol (4‐TBP). Phenolic derivatives are structurally similar to tyrosine, the initial substrate of tyrosinase in the biochemical synthesis of melanin. Therefore, it has been proposed that phenolic derivatives compete with tyrosine for hydroxyla‐tion by tyrosinase and interfere with the completion of melanin synthesis and/or generate cytotoxic intermediates. Our results demonstrated that 4‐TBP competitively inhibited both tyrosine hydroxylase and dihydrox‐yphenylalanine (DOPA) oxidase activities of tyrosinase, i.e., the first two catalytic steps in the biochemical conversion of tyrosine to melanin in cultured human melanocytes. This inhibition occurred at concentrations that did not influence the viability of melanocytes. The tyrosinase activity inhibited by 4‐TBP was recovered after removing the treatment. 4‐TBP did not affect the function of other enzymes, such as succinate‐tetra‐zolium reductase, acid phosphatase and sulfatase. Since depigmentation occurred without a cytotoxic response after exposure of melanocytes to low concentration of 4‐TBP, it is unclear whether the interaction between 4‐TBP and tyrosinase leads to the destruction of the melanocytes in‘contact/occupational’vitiligo.
Ephelides are More Related to Pigmentary Constitutional Host Factors than Solar Lentigines
Authors: T.BASTIAENS MAARTEN , WESTENDORP RUDI G.J. , VERMEER BERT J. , BAVINCK JAN N. BOUWES
Published: July 2006

Ephelides and solar lentigines are benign pigmented spots, which are currently associated with an increased risk of skin cancer. These two pigmented spots are known to be discriminated by their clinical, histological, and electron microscopic characteristics, even though occasional misclassification can occur because of their similarity. It has also been questioned whether these spots are not one and the same. In this study, we have attempted to differentiate between these two pigmented spots with the use of a standardized protocol for clinical examinations on 272 healthy volunteers, paying particular consideration to their pigmentary and constitutional host factors. We found that solar lentigines 1) are more prevalent than ephelides, 2) increase in prevalence and number with higher age, and 3) are most prevalent on the trunk and occur more frequently in males than in females. A trend is also observed whereby ephelides 1) loose their prevalence with age, 2) become equally distributed on the face, arms, and trunk, and 3) occur more frequently in females. An intimate association of ephelides, but not solar lentigines, has been found with hair color and skin type. All of these findings are in agreement with most of those reported in the literature, supporting the view that ephelides and solar lentigines are different types of pigmented lesions.
Location and Catalytic Characteristics of a Multipotent Bacterial Polyphenol Oxidase
Authors: FERNÁNDEZ EVA , SANCHEZ‐AMAT ANTONIO , SOLANO FRANCISCO
Published: July 2006

The melanogenic marine bacterium Marinomonas mediterranea contains a multipotent polyphenol oxidase (PPO) able to oxidize substrates characteristic for tyrosinase and laccase. Thus, this enzyme shows tyrosine hydroxylase activity and it catalyzes the oxidation of a wide variety of o‐diphenol as well as o‐methoxy‐activated phenols. The study of its sensitivity to different inhibitors also revealed intermediate features between laccase and tyrosinase. It is similar to tyrosinases in its sensitivity to tropolone, but it resembles laccases in its resistance to cinnamic acid and phenylthiourea, and in its sensitivity to fluoride anion. This enzyme is mostly membrane‐bound and can be solubilized either by non‐ionic detergent or lipase treatments of the membrane. The expression of this enzymatic activity is growth‐phase regulated, reaching a maximum in the stationary phase of bacterial growth, but l‐tyrosine, Cu(II) ions, or 2,5‐xylidine do not induce it. This enzyme can be separated from a second PPO form by gel permeation chromatography. The second PPO is located in the soluble fraction and shows a sodium dodecyl sulfate (SDS)‐activated action on the characteristic substrates for tyrosinase, l‐tyrosine, and l‐dopa, but it does not show activity towards laccase‐specific substrates. The involvement of the multipotent PPO in melanogenesis and its relationship with the SDS‐activated form and with the alternative functions proposed for multicopper oxidases in other microorganisms are discussed.
The Changing Pore Structure of Aging Human Mandibular Bone1
Authors: Atkinson P.J. , Hallsworth A.S.
Published: July 2006

The spatial structure of human mandibular bone has been studied using microradiography, scanning electron microscopy, and methacrylate replication. Microradiographs have demonstrated lamellar organization and mineralization. Methacrylate replicas have been examined by scanning electron microscopy which revealed the complex structure and inter‐connection of the vascular, lacunar, and canalicular spaces. The spatial replicas, representing the pore volume, have been dispersed ultrasonically and separated by sedimentation in a fluid column. The harvested methacrylate replicas of the three types of space have been weighed and knowing the density of methacrylate (1.18g/ml) their volumes determined by calculation. Pore volume increases with age. The vascular space makes the greatest contribution to this increasing porosity with age. Although lacunar volume increases with age, their numbers may fall. Canalicular volume appears to fall with age. This method has provided more information about the contribution the three different spatial compartments make to the increasing porosity of aging bone. There is no difference in the volume of these compartments in alveolar and basal mandibular bone but their distribution indicates that some of the smaller channels are more readily obstructed in alveolar bone.
Denture Wearers' Awareness of their Vertical Dimension
Authors: ÖWall Bengt
Published: July 2006

A method of analyzing facial proportions in evaluating occlusal vertical dimension was used in a test on 71 complete denture wearers aiming to find a way to rank denture wearers with different stages of reduced vertical dimension and development an instruction for patients' self judgment. By use of face drawings on a proforma the patients ranked themselves into one of four classes. The investigator also ranked the patients into these classes. There was a significant correlation (p<0.01) between the ranking by patient and investigator. The face proportions were also measured with an instrument. The distances nasion‐rima oris and subnasale‐gnathion were established. When ranking into classes, there was a significant (p<0.0001) correlation between the ranking by the investigator and the measurements. The results show that it may be possible to use information of facial proportions to give complete denture wearers a way of assessment of face height and thus a reason to consult a dentist in case of suspicion of reduced vertical dimension.
An Introduction to a Symposium in Geriatric Dentistry: Issues in Gerontology
Authors: Bonner Joseph , Harris William
Published: July 2006

The papers in this collection address geriatric dentistry at a time when society is rapidly becoming older. More than ever before, all dental care providers must understand the special needs of elderly patients and the unique biological features of the aged person that affect the diagnosis and prognosis of oral pathology. Attitudes about aging in the elderly must be discussed within the context of the health care setting so we can address the needs for social change, particularly in the dental and medical professions. This symposium brings together a series of papers on topics that are being researched in geriatric dentistry. The topics are diverse, including methods to finance dental care, psychiatric considerations, temporomandibular joint dysfunction, prosthodontics, artificial saliva and nutritional factors, immunology and the new frontiers in dental science, periodontal disease and oral cancer. And as an epilogue to our theme, a dentist with a primarily geriatric practice reflects on the difficulties and the rewards of the elderly patient. Improving the quality of life is the goal of aging research and to investigate aging legitimately we must ask in a systematic manner, what is aging? In this introduction, we discuss briefly the several theories of aging that are guiding research efforts.
An Alternative Method for Financing Care for the Non‐Institutionalized Geriatric Dental Patient
Authors: Marcus Marvin , Schoen Max H. , May Steve
Published: July 2006

Developing dental benefit programs for the expanding ambulatory geriatric population represents an important challenge for dentistry. This paper describes Blue Cross of California's experience in developing and providing a dental benefit as part of a HMO. supplement to the Medicare program. A study of a randomly selected sample of 133 Ultra Care enrollees was conducted in a small California city. A dental record review was performed on those individuals who accessed dental care. Patterns of utilization, distribution of planned and rendered treatment, and level of care achieved are presented. The experience of those patients compared to another sample of Ultra Care patients in a California city of comparable size, had similar care patterns. The major difference between the two patient populations was the tendency of one practice to repair existing prosthetic appliances, while the other practice tended to replace the existing appliances. The method of determining a capitation rate for these geriatric enrollees, using this data, is presented.
Hematological and Immunological Changes with Age
Authors: Wolf Norman S.
Published: July 2006

The development of both myeloid cells and immunocytes from a common stem cell precursor, their differentiated pathways, functions and the factors which modulate them are briefly reviewed here. The age‐related decline (or lack of it) for the several cell lines is outlined, as well as the effect of this upon life processes and homeostasis. The results from two approaches to extending high levels of immune responses in aged mice are reviewed.
Mineralized Tissue in Aging1
Authors: Somerman M.J.
Published: July 2006

Mineralized tissues undergo continuous remodeling through an appropriate balance in activity of osteoblasts, which regulate bone formation, and osteoclasts, which regulate bone resorption. Identification of the factors which control the osteogenic process has not yet been accomplished. Such identification is vital however, if we are to understand any aberrations in remodeling, that may occur with disease and/or aging. It is known that aging is accompanied by a decrease in absolute bone volume, which may be attributed to alterations in bone specific factors that regulate osteoblast and osteoclast function. In order to better understand age associated bone changes, the author and colleagues have compared extracts of human fetal bone with adult bone using a chemotactic assay, SDS‐polyacrylamide gel electrophoresis and molecular sieve chromatography. The results show that the extract of adult bone, when compared with fetal bone, had a relative increase in organic components of lower molecular weight. Second, that chemoattractant activity was present in the extract of fetal bone, but not of adult bone. These differences may in part be related to the clinical condition of increased fracture rate and decreased fracture healing and bone remodeling in older individuals when compared with younger populations.
Speech and Swallowing in the Elderly
Authors: Sonies Barbara C. , Stone Maureen , Shawker Thomas
Published: July 2006

Normal speech and swallow depend on the integrity of the oral motor system and the underlying processes of respiration, phonation, sensation, resonance and articulation. A variety of age‐related changes occur in the oral peripheral mechanism, some of which affect speech and swallow. Nonpathologic changes in the thoracic and laryngeal structures that serve to reduce the vital capacity of the lungs and produce perturbations in the acoustic signal alter the quality of the aging voice. As one ages, the oral mucosa reportedly thins, salivary flow may be decreased, and the sensory and motor integrity of the tongue musculature is altered. The effect of such changes on speech articulation and voice production in the elderly is discussed. Although not dependent on one another, speech and swallowing use many of the same oral structures and underlying physiologic mechanisms. The anatomic and physiologic changes in the aging pharvngeal area and oral tract that can affect swallowing are reviewd and studies of these changes are discussed. Viewing the oral area and vocal tract has required invasive, cumbersome or dangerous radiographic procedures, thereby limiting the quantity of research in this field. Recent work on the use of real‐time ultrasound imaging to view the oral soft tissues and dynamic lingual gestures in vivo during speech and swallow are reviewed and ongoing studies of speech and swallowing performance in normal aging persons using this technique are presented.
Age‐Related Changes in Collagen and Glycosaminoglycans of Rat Gingiva1
Authors: Shikata Hideo
Published: July 2006

Age‐related changes in collagen and glycosaminoglycans (GAGs) of rat gingiva were studied biochemically and histologically. The components of isolated GAGs were identified as dermatan sulphate, hyaluronic acid, and heparan sulphate. In histological studies, hyaluronic acid was present in all regions of the gingiva, whereas dermatan sulphate and heparan sulphate were present only in gingival connective tissue. However, there was no significant difference in the relationship between aging, and the content or distribution of GAGs. On the other hand, histological findings showed that collagen fibers were markedly increased in number and the vascular composition was decreased with increasing age. In biochemical studies, the content of collagen, especially of insoluble collagen, was greatly increased with age, whereas collagen biosynthesis and collagenolytic activity were markedly decreased. In addition, lysyl oxidase activity was also significantly decreased with age. The results indicate that the rate of collagen turnover decreases and collagen fibers increase in stability in rat gingiva with increasing age. These observed age‐related changes may affect the ability of gingiva to respond to local irritants.
Mouthdryness Among Patients in Longterm Hospitals
Authors: Johnson Gunilla , Barenthin Inkeri , Westphal Peter
Published: July 2006

The purpose of this investigation was to determine the mean salivary flow rate and the prevalence of mouthdryness and its relation to some background variables, such as oral condition, state of health and drug intake, among patients in somatic longterm hospitals. From 154 randomly selected patients salivary samples were taken from both parotid glands with Lashley cannules and 5 min stimulation with citric acid 2%. The sampling was repeated 3 times at a few days interval. The mean parotid flow rate among women was 0.28 ml/min and among men 0.47 ml/min. Forty‐three% of the patients had a rate ≤ 0.2 ml/min and 44% of these reported an almost constant sensation of dryness of mouth. Background factors with a significant effect on salivary flow rate could be found only among men taking tricyclic antidepressents especially in combination with diuretics. The flow rates among these institutionalized, old patients as a group were found to be consistently lower than rates found in earlier investigations among healthy old people.
Research in Geriatric Dentistry
Authors: Levy Barnet M.
Published: July 2006

Little is known about the aging per se of the oral mucosa, the salivary glands, the dental pulp or the periodontium. Even less is known about the relationship of the aging immune system to periodontal disease or to oral cancer. The interrelationship of aging body systems to oral biology is dentistry's challenge for the future. This conference paper is designed to stimulate some thinking, planning, and activity in the dental research community.
Xerostomia in the Elderly: Prevalence, Diagnosis, Complications and Treatment1
Authors: Ben‐Aryeh H. , Miron D. , Berdicevsky I. , Szargel R. , Gutman D.
Published: July 2006

The prevalence of xerostomia was evaluated in 259 volunteers 70 ± 4.5 years old. Seventy–two (27.7%) complained of dry mouth. In 31 (11.8%) salivary secretion was under 0.1 ml/min. The xerostomic patients were compared to an age–matched control group. The main complaints of xerostomia were dry mouth during the day, dry throat, burning sensation of the tongue, difficulty in swallowing, and taste disturbances. Systemic diseases frequent in the xerostomic patients were heart failure and hypertension. Chronic renal failure, depression, rheumatoid arthritis, and hypothyroidism were also encountered. The medications most frequently used by the xerostomic patients were parasympatholytics, sympatholytics, and diuretics. A higher frequency of active caries, gingivitis, and dryness of the mucosa was detected in the xerostomic patients. A significantly higher response to stimulation, elevated salivary calcium, and lowered oral pH were found in this group. Xerostomia was found to be related o t systemic diseases, medications, or a combination of these factors. The importance of saliva for maintaining oral health was also observed. Twenty–nine patients suffering from xerostomia were treated with an artificial saliva. On reexamination after one month, most of them reported improvement, and a significant increase in salivary flow rate was found.