bluuebunny/crossref_metadata_2025 huggingface dataset:
A Mediational Model Relating Sociotropy, Ambivalence Over Emotional Expression, and Disordered Eating
Authors: Krause Elizabeth D. , Robins Clive J. , Lynch Thomas R.
Published: July 2006

Two factors that have been found to predict eating disorders are sociotropy or dependent personality style and ambivalence over emotional expression, but there has been little consideration of the relationship between them and how this relationship may contribute to an understanding of eating disorders. A mediational model is proposed in which high sociotropy leads to greater ambivalence over expressing emotions, which in turn increases vulnerability to eating disorders. Consistent with predictions, among 115 college women, a high level of sociotropy was associated with a high level of ambivalence over emotional expression, which in turn was associated with increased disordered eating. Furthermore, ambivalence over emotional expression significantly mediated the effect of sociotropy on disordered eating, even when controlling for depression level. Findings are considered within a developmental framework, and treatment implications are discussed.
Harassed Bodies: An Examination of the Relationships Among Women's Experiences of Sexual Harassment, Body Image, and Eating Disturbances
Authors: Harned Melanie S.
Published: July 2006

The present study examined the relationships among sexual harassment and body image and eating disturbances using a sample of 195 undergraduate women. Sexual harassment was associated with a variety of eating disorder symptoms, even when controlling for experiences of sexual abuse/assault and physical abuse. Whereas sexual abuse/assault and physical abuse appear to be nonspecific risk factors for such symptoms, sexual harassment was more closely associated with eating disorder symptomatology than other types of psychological distress. The results of structural equation modeling better supported a model in which body image and eating disturbances were outcomes rather than antecedents of sexual harassment. Finally, several analyses indicated that disordered eating may function as a way to cope with the negative emotions associated with sexual harassment.
College Students' Visions of Power and Possibility as Moderated by Gender
Authors: Lips Hilary M.
Published: July 2006

The research literature, the shortage of women in positions of visible leadership, and the media's treatment of powerful women suggest that cultural prescriptions for power and leadership mesh uncomfortably with expectations for women in many contexts. To explore the ways in which young women and men may be absorbing cultural messages about power and gender, this study investigated the ways in which university students imagined their “possible powerful selves.” Respondents provided written descriptions of their possible selves as persons with power, political leaders, chief executive officers, and directors of scientific research centers as well as ratings of how possible and how positive such roles would be for them. Women rated the possibility of becoming a person with power or a political leader lower than men did. Women were also significantly more likely than men to anticipate relationship problems associated with the political leader role.
Instrumental and Expressive Traits, Trait Stereotypes, and Sexist Attitudes: What Do They Signify?
Authors: Spence Janet T. , Buckner Camille E.
Published: July 2006

College students rated the typical male and female student and themselves on 22 instrumental (I) and 16 expressive (E) items from the PAQ (Spence & Helmreich, 1978) and the BSRI (Bem, 1974), as well as on the BSRI items “masculine” and “feminine.” They also completed measures of gender stereotypes and sexist attitudes. Significant gender stereotypes were found on all but two I and E items in both genders. Significant gender differences in self-report were found on all the E items but on only 41% of the I items, confirming our hypotheses that societal changes have led women to develop more agentic self-conceptions. The pattern of relationships found between the self-report, stereotype, and attitude measures supports the utility of a multidimensional approach to gender. Responses to the items “masculine” and “feminine” confirm the implications of our hypothesis that these items primarily assess men's and women's basic sense of gender identity.
The Social Stigma of Menstruation: Fact or Fiction?
Authors: Kowalski Robin M. , Chapple Tracy
Published: July 2006

In a study examining the effects of a social stigma on impression management concerns, 28 menstruating and 30 nonmenstruating women were interviewed by a male confederate who either was or was not aware of their menstrual condition. Relative to menstruating women who thought the interviewer was unaware of their menstrual condition, menstruating women who believed that the interviewer knew they were menstruating perceived that the interviewer liked them less, yet were less motivated to make an impression on him. Nonmenstruating women reported more self-presentational motivation and perceived that the interviewer viewed them more positively than he did the menstruating women. These results suggest that the interviewer's knowledge of their menstrual condition inhibited menstruating women's self-presentational motivation. Implications of this social stigma for interpersonal relationships are discussed.
Sexist Discrimination May Account for Well-Known Gender Differences in Psychiatric Symptoms
Authors: Klonoff Elizabeth A. , Landrine Hope , Campbell Robin
Published: July 2006

It was hypothesized that women may have more depressive, anxious, and somatic symptoms than men because they experience a deleterious stressor that men do not: sexist treatment. A total of 255 students (180 females, 75 males) at a state university completed an anonymous questionnaire containing measures of these symptoms. Women were found to exhibit significantly greater symptoms than men on all of them. Further, women who experienced frequent sexism had significantly more symptoms than men on all symptom measures, whereas women who experienced little sexism did not differ from men on any symptom measure. These findings suggest that gender-specific stressors not only play a role in psychiatric symptoms among women but may account for well-known gender differences in those symptoms as well.
Understanding The Sexuality of Mexican-Born Women and Their Risk for Hiv/Aids
Authors: Snyder V. Nelly Salgado de , Acevedo Andrea , Díaz-Pérez María de Jesús
Published: July 2006

Participants in this study were 300 Mexican women of rural origin who were born and raised in villages of that country and who belong to one of three groups: married and living with their husbands in Los Angeles, California ( n = 100), married to migrant workers but living in Mexico ( n = 100), and living in Mexico with their spouses ( n = 100). Trained female professionals conducted face-to-face interviews in Spanish, in Mexico and in the United States. The purpose of this study was to identify specific sexual practices, coping strategies in sex-related situations, and fears and concerns regarding sexual intercourse. This article analyzes how these elements place Mexican rural-origin women at risk for HIV/AIDS. It discusses the need to design intervention strategies to prevent HIV/AIDS that take into consideration the limited power of women in traditional societies and the cultural precepts that promote gender roles characterized by male dominance and female submissiveness in the sexual arena.
Theophylline Effects on Normal Uveal Melanocytes in Culture: An Ultrastructural Study
Authors: HU FUNAN , MAH KUNIE , TERAMURA DINAH J.
Published: July 2006

Theophylline enhances maturation and differentiation of uveal melanocytes. By electron microscopy, we showed that theophylline changes small, dendritic melanocytes into large, platelike cells; it also enhances DOPA reaction as evidenced by increased deposition of DOPA reaction products in dilated cisternae and vesicles around the Golgi region. The effect is partially reversible in choroidal melanocytes but irreversible in iridial cells. It appears that theophylline, in addition to inducing tyrosinase activity, accelerates the maturation and/or aging that normally occurs in cultured melanocytes when incubation is prolonged.
Studies on Cellular Adhesion of Xenopus laevis Melanophores: Modulation of Cell‐Cell and Cell‐Substratum Adhesion In Vitro by Endogenous Xenopus Galactoside‐Binding Lectin
Authors: MILOS NADINE C. , WILSON H. CHRIS , MA YAN‐LING , MOHANRAJ THOMAS M. , FRUNCHAK YVETTE N.
Published: July 2006

We have investigated cell‐cell and cell‐substratum adhesion of Xenopus laevis neural crest cells at various stages of melanophore differentiation. Single‐cell suspensions were obtained by trypsinization and aggregated in a cell‐cell adhesion assay. Unpigmented cells did not adhere while the rate of adhesion of melanophores correlated with the degree of melanization. Melanophore cell‐cell adhesion decreased significantly in the presence of beta‐galactosidase, which suggests that cell‐surface galactose is involved. Beta‐galactoside‐binding lectin has been isolated and purified from embryos at the stage of neural crest migration. When added to aggregating cells smaller, looser clusters formed compared to controls. When lectin was added to cells in stationary culture to test cell‐substratum adhesion, melanophores spread more smoothly and formed more regular spacing patterns. These results suggest that this lectin can modulate receptors used in cell‐cell and cell‐substratum adhesion of melanophores.
Effects of Exogenous Guanosine on Chromatophore Differentiation in the Axolotl
Authors: FROST SALLY K. , ROBINSON SCOTT J. , CARSON MARY KAY , THORSTEINSDOTTIR SOLVEIG , GIESLER JAMES
Published: July 2006

Guanosine is shown to dramatically alter the pigment phenotype of axolotls by suppressing melanization and enhancing the biosynthesis and deposition of purine‐derived pigments. Phenotypic changes caused by guanosine are manifested by altered chromatophore differentiation patterns such that few black pigment cells (melanophores) differentiate (and those that do are punctate and necrotic in appearance), whereas the development of yellow (xanthophore) and reflecting (iridophore) pigment cells is enhanced. Mechanisms for changes in chromatophore differentiation, and thus pattern formation, are discussed, including the possibility that pigment cells may undergo transdifferentiation in vivo.
Distal Retinal Pigment of the Fiddler Crab, Uca pugilator: Release of the Dark‐Adapting Hormone by Methionine Enkephalin and FMRFamide
Authors: KULKARNI GUNDERAO K. , FINGERMAN MILTON
Published: July 2006

The neuropeptides methionine enkephalin and FMRFamide, when injected into intact fiddler crabs, Uca pugilator, produce dark adaptation of the distal retinal pigment. Furthermore, both neuropeptides stimulate release of distal retinal pigment dark‐adapting hormone activity from the isolated eyestalk neuroendocrine complex. It is hypothesized that both neuropeptides, when injected into intact fiddler crabs, act only indirectly on the distal retinal pigment, by stimulating release of this dark‐adapting hormone.
Calcium‐Dependent Irreversible Effect of Ionophore A23187 on Melanophores
Authors: HADLEY MAC E.
Published: July 2006

The calcium ionophore, A231187, induces a Ca2+‐dependent movement (dispersion) of melanosomes within skin melanophores of the lizard, Anolis carolinensis, in vitro. The effects of A23187 are irreversible, since after repeated rinsing of the skins in the absence of the ionophore they will always darken in Ringer containing Ca2+ but will immediately lighten when transferred to Ca2+‐free Ringer. These results suggest that the ionophore is irreversibly localized to the melanophore membrane and that its melano‐some‐dispersing effect is continuously dependent upon extracellular calcium.
Transmission and Scanning Electron Microscopy and Freeze‐Fracture Replication of Normal Human Melanocytes and Human Melanoma Cells in Tissue Culture
Authors: BREATHNACH A.S. , PÄTZOLD H.C. , ROBINS E.J. , BHASIN Y.D. , ETHRIDGE L. , NAZZARO‐PORRO M.
Published: July 2006

Basic LM, TEM, SEM, and FFR appearances of a pure line of normal human melanocytes derived from foreskin, and a human melanoma line, in cell culture are described. Normal melanocyte cultures exhibit side by side, cells of widely different melanogenic activities—possible clones—and melanosomes of bizarre shape and internal structure are frequent. Aggregates of melanosomes, with or without associated amorphous material, and with no discernible limiting membrane are present within many cells, and occasional simple specialised contacts occur between apposed cells. On replicas of plasma membrane of normal melanocytes, particle densities and diameters on P and E fracture faces were within the ranges for cells in general, and equivalent data for the melanoma cells were not significantly different. Similarly, there was no difference in density of distribution or diameter of nuclear pores between the normal and the tumoural cells.
Understanding Colors in Nature
Authors: BOHREN CRAIG F.
Published: July 2006

There are two ways in which white light is transformed into colored light by interaction with matter: absorption and scattering. Absorption transforms light into other forms of energy, whereas scattering redirects it. Reflection, refraction, and diffraction are not distinct from scattering but rather are manifestations of it. There is a hierarchy of theories for describing any color phenomenon. For example, many features of rainbows—but not all—can be described satisfactorily by geometrical optics. More accurate descriptions require more exact theories. What one observes when matter is illuminated depends on its disposition. A microscope slide scatters light mostly in two directions. When smashed to bits, it scatters in all directions. Yet its chemical composition has not changed. Glass particles, unlike those in smoke, are usually too large to give colors upon scattering. The colors one sees when smoke is illuminated depend on whether one observes light that has or has not been scattered. Moreover, particle size is crucial in determining what colors are observed. As with scattering, there is a hierarchy of theories of absorption. One can content oneself with an empirical description of absorption or seek a fuller understanding by appealing to microscopic theories. Yet it is sometimes difficult to associate a definite microscopic mechanism with a given absorption feature. Ice is intrinsically blue, yet this cannot be attributed readily to a specific mechanism. Beer has no yellow absorption feature; absorption by it is least in the red and rises steadily toward the blue. Over short paths, beer is yellow; over long paths, it is reddish. Selective scattering by molecules causes the blue of the sky. Yet it is not uniformly blue. To understand why requires invoking multiple scattering. Snow is another multiple scattering medium. Although we usually think of snow as white, deep within it there is blue light more vivid than the bluest sky. This is the result of multiple scattering by particles that are not selective scatterers but selective absorbers.
Photo‐Induced Events in the Human Melanocytic System: Photoaggression and Photoprotection
Authors: CESARINI JEAN‐PIERRE
Published: July 2006

The human skin is submitted to solar, essentially ultraviolet radiation (UVR), aggressions, and develops, for sufficient doses, erythema and pigmentation. The individual sun‐sensitivity depends on the nature and the quantity of melanins present in the epidermis. These parameters are inherited as genetic traits which account for the large variations of the constitutive and adaptive pigmentation encountered in the caucasian populations. From red‐haired skin‐sensitive individuals, to dark‐haired sun‐resistant individuals, phaeomelanins (red) and eumelanins (black) are mixed in variable proportions. Pure melanins extracted from red hairs and black hairs behave differently when submitted to ultraviolet radiations: phaeomelanins develop aggressive species of molecules responsible for DNA damages, mutations, and cell death. On the contrary, eumelanins are less toxic for the major cellular metabolisms. The sun‐sensitive populations suffer from more skin cancer of all types than the dark ones. In particular, they are exposed significantly to higher risk of melanoma and to the risk of bearing more nevi following large solar exposures early in the life.
Extra‐Cutaneous Melanin
Authors: BREATHNACH A.S.
Published: July 2006

Extra‐cutaneous melanocytes derive from either the neural crest, the outer wall of the optic cup, or the cranial neural tube. Those of neural crest origin reach most bodily regions, and may give rise to primary melanoma in various tissues. The Kupffer cell produces a form of melanin, but is hardly a melanocyte. Melanocytes of the internal ear may be concerned with secretion of endolymph, trans‐epithelial ion transport, and with protection against ototoxic drugs and high‐intensity noise damage. There is evidence from albino animals that retinal pigment epithelium determines co‐ordinates of the neural retina, and its decussation pattern during development.

Neuromelanin derives from Dopamine, and is found in dopaminergic neurons widely distributed throughout the brain‐stem and hypothalamus, and which project to the striatum and limbic system. Parkinsonism is due to degeneration of melanin‐containing dopaminergic neurons of locus coeruleus and substantia nigra, and MPTP provides an investigative probe for studying the causes of Parkinsonism. Neuromelanin should not be regarded as a waste‐product, but as something which can affect the firing properties of neurons with specific functional effect.
Responses of Cultured Melanocytes to Defined Growth Factors
Authors: HALABAN RUTH
Published: July 2006

To proliferate in vitro, normal melanocytes, unlike normal fibroblasts, require specific growth factors in addition to those supplied in serum. The substances that promote melanocyte proliferation, such as 12‐O‐tetradecanoyl‐phorbol‐13‐acetate (TPA) and stimulators of cyclic adenosine monophosphate (cAMP), also promote pigmentation. Consequently, cell division and expression of at least some differentiated functions are not mutually exclusive for melanocytes. At present, the only known natural growth factor that can replace TPA in normal human melanocyte cultures is basic fibroblast growth factor (bFGF). Like TPA, bFGF is effective, most of the time, only in the presence of added cAMP. Some preparations of bFGF, however, may have a highly labile, intrinsinc cAMP stimulatory activity. It is thus possible that bFGF can assume two forms, dependent on and independent of cAMP stimulatory activity. Alternatively, a second factor may exist in pituitary glands that co‐purifies with bFGF but deteriorates with storage. Abnormal melanocytes in culture, such as those derived from dysplastic nevi and primary melanomas, depend on the specific factors (bFGF and cAMP), whereas melanocytes from metastatic melanomas do not
Genetic Regulation of Melanocyte Differentiation
Authors: TAKEUCHI TAKUJI , YAMAMOTO HIROAKI
Published: July 2006

Melanocytes originate from the neural crest in vertebrates and migrate to the body surface where they differentiate into functional cells. Genes involved in melanocyte differentiation can be classified into two groups. One of them consists of the functional genes that control proteins specific to the function of the melanocyte. As the representative gene of this category, albino (c) locus in the mouse is considered to control tyrosinase, the key enzyme in melanogenesis. cDNA for mouse tyrosinase has been cloned and sequenced. The cDNA can be used to detect tyrosinase mRNA synthesized during melanocyte differentiation. On the other hand, genes such as brown (b) or pink‐eyed dilution (p) have been assumed to control melanosome proteins.

The other category consists of genes that regulate the expression of these functional genes directly or indirectly. In the mouse, so‐called white‐spotting genes and genes of the agouti series are considered to fall into this category. Based on the fact that mutations at the white‐spotting loci result in the absence of melanocytes in a particular area of skin, it is assumed that some of these loci control the factors that promote either differentiation or migration of melanoblasts and are candidates for the classic regulator genes

Genes at the agouti (a) locus in the mouse determine the type of melanin synthesized in hair follicle melanocytes, that is eumelanin or pheomelanin. An interesting feature of this locus is that the site of gene action is not within the melanocytes but in the cells surrounding them. The results of our study indicate that the gene product of the a‐locus interacts with α‐MSH at the α‐MSH receptor site, regulates the cellular cAMP level via a signal transduction system and, in turn, determines the type of melanin synthesized in the cells.
Human Albinism and Animal Models of Albinism
Authors: WITKOP CARL J. , KING RICHARD A. , TOWNSEND DeWAYNE
Published: July 2006

Ten phenotypic forms of oculocutaneous albinism (OCA) and four forms of ocular albinism (OA) have been identified in man. All have optic neuronal decussation defects at the optic chiasm. Thus any proposed animal model for these disorders must share optic neuronal decussation defects in addition to hypopigmentation. Three, tyrosinase‐negative (ty‐neg), yellow mutant (ym), and platinum (pt), OCA appear to be allelic in humans. Two, ty‐neg and pt, OCA appear to be analogous to c‐locus mutants c/c and cp/cp in mice, but no homologue is known in mice for ym OCA. Tyrosinase‐positive (ty‐pos) OCA, which is nonallelic with ty‐neg OCA, shares many morphological and biochemical features with pink‐eyed mice. Chediak‐Higashi syndrome (CHS) and Hermansky‐Pudlak syndrome (HPS) appear to be due to genes acting extrinsic to the melanin pathway. CHS is homologous with beige in mice. HPS was investigated in northwestern Puerto Rico, where it affects approximately 1 in 2,000 persons. Approximately 68% of 37 deceased HPS patients died from sequelae of ceroid storage disease, restrictive lung disease between ages 35 and 46 years (43%), and granulomatous colitis (8%) or hemorrhage (16%). The most accurate and consistent diagnostic feature of HPS is lack of platelet dense bodies. HPS patients with ceroid storage disease had high urinary levels of long‐chain isoprenoid alcohols, dolichols, similar to that seen in the neuronal‐ceroid lipofuscinoses (Batten disease). Dolichols are constituents of lysosomes, and their elevation in HPS suggests that this syndrome carries a lysosomal defect. There is no degradative pathway for ceroid and dolichols, which are eliminated by exocytosis. The exocytic process is thought to involve a thioendoproteinase. Pale‐ear mice have been proposed as a model for HPS; their platelets lack dense bodies, and they are depigmented. Leupeptin, a thioendoproteinase inhibitor, administered to 100‐day‐old pale‐eared and black wild‐type C57 mice for 10 days resulted in the accumulation of ceroid in tissues in the same pattern as that in HPS, but granulomas of gut or fibrosis of lungs were not seen. Determinations of homology between mice and men at the molecular level is now possible with the isolation of mouse tyrosinase by Yamamoto et al. and isolation by Kwon et al. of human tyrosinase mapping at the c‐locus in mice.
Dysplastic Nevus Syndromes
Authors: ELDER DAVID. E.
Published: July 2006

Dysplastic nevi (DMN) were first recognized as an autosomal dominant genetic marker of melanoma risk in hereditary cutaneous melanoma (HCMM) kindreds, families in which at least two melanomas have occurred. Subsequently, DMN have been identified in people with a personal but no family history of melanoma (SCMM), and with no history of melanoma. The lesions themselves may similarly be familial (FDMN) or sporadic (SDMN). A good deal is known about HCMM/FDMN kindreds and about patients with SCMM and DMN, while information about other subsets of DMN cases is slowly accumulating. Clinical evidence suggests that DMN may usually be familial when case‐finding is adequate.

Although DMN are potential precursors of melanoma, the risk of progression of individual lesions is low, and their major significance is as markers of prospective risk for melanoma. This risk is heterogeneous, and there are important interactions with other risk factors, especially prior personal or familial melanoma. Traditional risk factors for melanoma, such as susceptibility to sunburn and ability to tan, may be expected to interact with the DMN trait to establish groups at heterogeneous risk. These groups may be regarded as syndromes of DMN cases, but to avoid confusion, it seems more appropriate to refer to cases by descriptive labels such as FDMN with HCMM, FDMN with personal CMM, FDMN without CMM, SDMN, and so on.
L‐Tyrosine, L‐DOPA, and Tyrosinase as Positive Regulators of the Subcellular Apparatus of Melanogenesis in Bomirski Ab Amelanotic Melanoma Cells
Authors: SLOMINSKI ANDRZEJ , MOELLMANN GISELA , KUKLINSKA ELIZABETH
Published: July 2006

In cultured cells of the Bomirski Ab amelanotic hamster melanoma line, the substrates of tyrosinase, L‐tyrosine, and L‐DOPA induce the melanogenic pathway. In this report, we demonstrate that these substrates regulate the subcellular apparatus involved in their own metabolism and that this regulation is under the dynamic control of one of the components of this apparatus, tyrosinase, via tyrosine hydroxylase activity. Culturing cells with nontoxic but melanogenically inhibitory levels of phenylthiourea (PTU; 100 μM) strongly inhibits induction of both the tyrosine hydroxylase and DOPA oxidase activities of tyrosinase by Ltyrosine (200 μM) but has no effect on the induction of either activity by L‐DOPA (50 μM). De novo synthesis of premelanosomes precedes the onset of tyrosine‐induced melanogenesis. Thereafter, increases in the population of melanosomes (likewise inhibited by PTU) correlate positively with increases in tyrosinase activity induced by L‐tyrosine. Melanogenesis induced by L‐DOPA in the absence of L‐tyrosine is rate‐limited not by tyrosinase but by inadequate melanosome synthesis. Our findings indicate that in Bomirski Ab amelanotic hamster melanoma cells the synthesis of the subcellular apparatus of melanogenesis is initiated by L‐tyrosine and is regulated further by tyrosinase and L‐DOPA, which serves as a second messenger subsequent to tyrosine hydroxylase activity.
Control of Melanoblast Differentiation in Amphibia by α‐Melanocyte Stimulating Hormone, a Serum Melanization Factor, and a Melanization Inhibiting Factor
Authors: FUKUZAWA TOSHIHIKO , BAGNARA JOSEPH T.
Published: July 2006

A ventrally localized melanization inhibiting factor (MIF) has been suggested to play an important role in the establishment of the dorsal‐ventral pigment pattern in Xenopus laevis [Fukuzawa and Ide: Dev. Biol., 129:25–36, 1988]. To examine the possibility that melanoblast expression might be controlled by local putative MIF and melanogenic factors, the effects of α‐melanocyte stimulating hormone (α‐MSH), a serum melanization factor (SMF) from X. laevis or Rana pipiens, and MIF on the “outgrowth” and “melanization” of Xenopus neural crest cells were studied. Outgrowth represents the number of neural crest cells emigrating from cultured neural tubes, and melanization concerns the percentage of differentiated melanophores among the emigrated cells. MSH or SMF stimulate both outgrowth and melanization. The melanogenic effect of Xenopus serum in this system is more than twice that of Rana serum. The actions of MSH and Xenopus serum on melanization seem to be different: 1) Stronger melanization is induced by Xenopus serum than by MSH, and the onset of melanization occurs earlier with Xenopus serum; 2) MSH stimulates melanization only in the presence of added tyrosine; and 3) MSH causes young melanophores to assume a prominent state of melanophore dispersion during culture, while Xenopus serum (10%) had only a slight dispersing effect and not until day 3. A fraction of Xenopus serum presumably containing molecules of a smaller molecular weight (MW <30 kDa) than that of a pigment promoting factor reported in calf serum [Jerdan et al.: J. Cell Biol., 100:1493–1498, 1985] produces the same remarkable melanogenic effects as does intact serum. While this fraction stimulates outgrowth, another fraction presumably containing larger molecules (MW > 100 kDa) does not. MIF contained in Xenopus ventral skin conditioned medium (VCM) inhibits both outgrowth and melanization dose dependently. When VCM is used in combination with MSH, the stimulating effects of MSH on both outgrowth and melanization are completely inhibited. In contrast, the stimulatory effects of Xenopus serum are not completely inhibited when combined with VCM, although melanization is reduced to approximately 40% that of controls. MIF activity was also found to be present in ventral, but not in dorsal, skin conditioned media of R. pipiens when tested in the Xenopus neural crest system. We suggest that ventrally localized MIF plays an important role in amphibian pigment pattern formation and that the interacting effects of MIF and melanogenic factors influence melanoblast differentiation, migration, and/or proliferation of neural crest cells to effect the expression of pigmentary patterns.
Ionic Requirements for Melanin Concentrating Hormone (MCH) Actions on Teleost Poecilia reticulata Melanophores
Authors: VISCONTI MARIA A. , CASTRUCCI ANA MARIA DE L. , MAC HADLEY E. , HRUBY VICTOR J.
Published: July 2006

Melanin concentrating hormone (MCH) is a cyclic heptadecapeptide, Asp‐Thr‐Met‐Arg‐Cys‐Met‐Val‐Gly‐Arg‐Val‐Tyr‐Arg‐Pro‐Cys‐Trp‐Glu‐Val, synthesized in the hypothalamus and released by the neurohypophysis of teleost fish. This hormone is a potent lightening agent of fish skin. This lightening results from the stimulation of a centripetal melanosome (melanin granule) migration to a perinuclear position within integumental melanophores.

MCH and related fragment analogues, MCH5‐17 and MCH1‐14 were used to investigate the ionic requirements for receptor activation by MCH on dermal melanophores of the fish Poecilia reticulata. In calcium‐free saline, the sensitivity of the melanophores to MCH and MCH1‐14 increased, whereas the sensitivity of the cells to MCH5‐17 decreased. Verapamil diminished the sensitivity to MCH5‐17, but did not affect melanophore responses to MCH or MCH1‐14. The melanosome aggregating response to MCH was not affected in the presence of tetrodotoxin or in sodium‐ or potassium‐free (choline‐substituted) saline. These results suggest that neither TTX‐sensitive sodium channels nor extracellular sodium or potassium ions play a role in MCH‐induced melanosome aggregation.

It is known that MCH and MCH1‐14 also exhibit MSH‐like melanosome dispersion within melanophores, skin darkening activity on fish melanophores whereas MCH5‐17 lacks this characteristic. Since the darkening activity of MCH and MCH1‐14 requires calcium, these analogues exhibited a diminished lightening (MCH‐like) activity in the presence of the divalent cation. In the absence of the N‐terminal tetrapeptide sequence (necessary for the expression of MSH‐like activity), a role for calcium on melanosome aggregation became evident. These results demonstrate a bifunctional role of calcium on melanosome movements.
Neutron‐Induced Gamma Dose From a Reactor Beam Filter for Boron Neutron Capture Therapy
Authors: HARRINGTON BAIBA V.
Published: July 2006

For the boron neutron capture therapy (NCT) of deep‐seated metastatic melanoma, an epithermal (up to a few keV energy) neutron beam from a reactor horizontal facility could be useful if the inherent contamination from fast neutrons and gamma rays could be minimised.

Calculations for ANSTO's 10 MW research reactor HIFAR have shown that, even though a filter material such as A1F3 attenuates the fast neutron dose, the beam quality improvement is counteracted by a relative increase in the gamma dose because of gammas arising from neutron captures in the filter material, particularly the aluminium. The aluminium gammas, most of which arise from thermal neutron capture, are hard and cannot be attenuated by lead or bismuth without comparable attenuation of the epithermal neutron flux. Addition of an absorber such as 6Li to the AlF3 filter was investigated as a means of reducing the hard gamma dose, but the improvement in beam quality was small and at considerable cost to dose intensity. Dose characteristics calculations confirmed the superiority of a tangential beam over a radial beam with better results from an unfiltered tangential beam than from an AlF3 filter in a radial beam.

This study showed conclusively that assessments of filter assemblies based on the effect of individual components on either the neutron or gamma dose in isolation are inadequate. In assessing any epithermal neutron filter, thermal neutron shield, and gamma shield combination, the total effect of each on the neutron, gamma, and boron‐10 dose must be considered.
A Trial to Improve the Analysis of Boron in Biological Materials
Authors: YOSHINO KAZUO , KAJIYAMA YUKARI , HONDA TADASHI , MORI YOSHIHIRO , HONDA CHIHIRO , ICHIHASHI MASAMITSU , MISHIMA YUTAKA
Published: July 2006

For the spectrophotometric determination of boron in biological materials, two decomposition methods were used. One is the alkali fusion method, and the other is the acid decomposition method using a uniseal decomposition vessel. A long‐range calibration curve for the former method was obtained by using an ultrapure sulfuric acid. The alkali fusion method was applied to samples into which paraboronophenylalanine (BPA) or its hydrochloric salt (BPAHCI) had been injected. By the acid decomposition method using a uniseal vessel, 50 mg dried liver was digested by a mixed solution of 1 ml conc, sulfuric acid and 6 ml 30% hydrogen peroxide. A problem exists, however, in that the hydrogen peroxide remaining in the decomposition solution must be eliminated without loss of boron.
Acute and Subacute Toxicity of 10B‐Paraboronophenylalanine
Authors: TANIYAMA KOHTARO , FUJIWARA HIROSHI , KUNO TAKAYOSHI , SAITO NAOAKI , SHUNTOH HISATO , SAKAUE MOTOYOSHI , TANAKA CHIKAKO
Published: July 2006

The acute and subacute toxicities of 10B‐paraboronophenylalanine (10B‐BPA) were investigated in the rat, according to the Good Laboratory Practice Standard for safety studies on drugs in Japan. In the acute toxicity test of 10B‐BPA, LD50 values of acidic 10B‐BPA for intraperitoneal and subcutaneous injections were 640 mg/kg for male and 710 mg/kg for female rats, and more than 1,000 mg/kg for male and female rats, respectively. The LD50 values of neutral 10B‐BPA for intraperitoneal and subcutaneous injections were more than 3,000 mg/kg for male and female rats. The difference in LD50 values between acidic and neutral 10B‐BPA may be attributed to the acidity of material. From the subacute toxicity test, in which the rats were injected daily subcutaneously for 28 days, the following toxic effects of 10B‐BPA were observed. Increase in ketone level in the urine was induced in all rats treated with 10B‐BPA. High dose of 10B‐BPA (1,500 mg/kg) induced increase in spleen weight and reticulocyte count, and decrease in hemoglobin count, thereby suggesting that 10B‐BPA causes hemolysis. Increases in the leukocyte count and the ratio of neutrophils and lymphocytes were also observed in rats treated with a high dose of 10B‐BPA. This may be attributed to local reactions at the injection site. There were no significant differences in the findings between control rats and rats treated with a low dose of 10B‐BPA (300 mg/kg). Thus, low doses of neutral 10B‐BPA may be available for use as a drug.
Use of Nude Mice in Experimental Neutron Capture Therapy With 10B‐BPA
Authors: TAMAOKI NORIKAZU , UEDA MASATO , TAMAUCHI SHUICHI , YAMAMOTO KUMIKO , MISHIMA YUTAKA
Published: July 2006

Mouse B16 melanoma allografts in nude mice were successfully treated by thermal neutron irradiation after IP injection of 10B‐paraboronophenylalanine hydrochloride. The tumor growth was significantly suppressed for 4 weeks after irradiation, compared with animals given neutron irradiation alone. Tumor‐bearing nude mice were shown to be useful for evaluating the treatment for melanoma.
Estimation of Absorbed Dose in the Covering Skin of Human Melanoma Treated by Neutron Capture Therapy
Authors: FUKUDA HIROSHI , KOBAYASHI TOORU , HIRATSUKA JUNICHI , KARASHIMA HIROSHI , HONDA CHIHIRO , YAMAMURA KEIZOU , ICHIHASHI MASAMITU , KANDA KEIJI , MISHBMA YUTAKA
Published: July 2006

A patient with malignant melanoma was treated by thermal neutron capture therapy using 10B‐paraboronophenylalanine. The compound was injected subcutaneously into ten locations in the tumor‐surrounding skin, and the patient was then irradiated with thermal neutrons from the Musashi Reactor at reactor power of 100 KW and neutron flux of 1.2 ± 109 n/cm2/s. Total absorbed dose to the skin was 11.7–12.5 Gy in the radiation field. The dose equivalents of these doses were estimated as 21.5 and 24.4 Sv, respectively. Early skin reaction after irradiation was checked from day 1 to day 60. The maximum and mean skin scores were 2.0 and 1.5, respectively, and the therapy was safely completed as far as skin reaction was concerned. Some factors influencing the absorbed dose and dose equivalent to the skin are discussed.
Ultrastructural Observations of Motile Iridophores From the Freshwater Goby, Odontobutis obscura
Authors: MATSUNO AKIRA , IGA TETSURO
Published: July 2006

The ultrastructure of “motile” iridophores of Odontobutis obscura and the changes in cell shape related to the motility were studied with electron microscopy. Various structural details were revealed by this method, and their importance is discussed. Of particular interest were the abundant microfilaments observed in the cortical cytoplasm. Cross‐sectional profiles of iridophores showed that, in an iridophore in the dendritic state, the platelets were scattered randomly throughout the centrosphere and its processes, so that the centrosphere appeared to be rather flat. In the punctate state, the platelets were gathered, in groups or in stacks with regular arrangements, in the centrosphere, which appeared to be ovoid in shape. The most notable finding was that, at this time, the processes from which the platelets were lost remained there without retracting. The results indicates clearly that the motility of the goby iridophores involves the migration of platelets within the fixed contour of each cell and that no amoeboidal changes in the shapes of the cells occur.
Linear and Cyclic α‐Melanotropin [4–10]‐Fragment Analogues That Exhibit Superpotency and Residual Activity
Authors: HADLEY MAC E. , MARWAN MOHAMED M. , AL‐OBEIDI FAHAD , HRUBY VICTOR J. , MARIA DE LAURO CASTRUCCI ANA
Published: July 2006

Two analogues of α‐MSH (Ac‐Ser‐Tyr‐Ser‐Met‐Glu‐His‐Phe‐Arg‐Trp‐Gly‐Lys‐Pro‐Val‐NH2), Ac‐[Nle4, Asp5, D‐Phe7, Lys10]α‐MSH4–10NH2 and Ac‐[Nle4, Asp5, D‐Phe7, Lys10] α‐MSH4–10‐NH2, were synthesized, and the melanotropic activities of the peptides were compared in several bioassays. Potencies were determined in the in vitro frog and lizard skin bioassays and in the S91 melanoma cell tyrosinase assay. Both analogues were equipotent or more potent than α‐MSH in all bioassays, and the activities of the analogues were prolonged compared to α‐MSH. The two analogues were very resistant to inactivation by purified proteolytic enzymes (α‐chymotrypsin, trypsin, and pepsin). The two peptides could be topically applied and transdermally delivered across the skin of mice in vivo, resulting in a shift from pheomelanogenesis to eumelanogenesis within follicular melanocytes. The cyclic analogue exhibited greater potency, prolonged activity, and stability against enzyme inactivation than did the linear peptide. The significance of the findings for the further design of melanotropin analogues is discussed, as in the possible relevance of these melanotropin analogues for use in biomedical studies.
Use of an Alpha‐Melanocyte‐Stimulating Hormone Analogue to Improve Alpha‐Melanocyte‐Stimulating Hormone Receptor Binding Assay in Human Melanoma
Authors: LIBERT ANITA , GHANEM GHANEM , ARNOULD ROLAND , LEJEUNE FERDY J.
Published: July 2006

In order to optimize the detection and measurement of α‐melanocyte‐stimulating hormone (α‐MSH) receptivity in human melanoma cells, and the authors replaced the natural hormone by [Nle4,D‐Phe7]‐α‐MSH, a more stable and potent analogue in the receptor binding assay commonly performed with α‐MSH. The following parameters were investigated: temperature, incubation time, number of cells, and ratio of labelled to unlabelled hormone. Optimal conditions for each assay were determined.

The results demonstrate that the analogue has identical binding sites to α‐MSH, as similar reciprocal displacements of each labelled (125I) hormone by serial dilutions of unlabelled α‐MSH or [Nle4,D‐Phe7]‐α‐MSH (10−12 M to 10−6 M) were obtained. To further compare the two hormones, we performed a screening of various human cell lines: ten melanomas and five nonmelanomas. The assay with [Nle4,D‐Phe7]‐α‐MSH yielded more receptor expression on six often melanoma lines against only four often with the natural hormone.

In conclusion, the use of radiolabelled [Nle4,D‐Phe7]‐α‐MSH analogue instead of labelled α‐MSH improved both sensitivity and reproducibility in this receptor binding assay on human melanoma lines.
Evidence for a Calcium/Calmodulin Involvement in Density‐Dependent Melanogenesis in Murine B16 Melanoma Cells
Authors: BUFFEY JAYNE A. , HILL SARAH E. , BLEEHEN STANLEY S. , THODY ANTHONY J. , NEIL S. MAC
Published: July 2006

Previous work from our laboratory has shown that both cyclic AMP and calcium/calmodulin appear to be involved in the regulation of melanogenesis in murine B16 melanoma cells. In these cells as in murine Cloudman S91 cells, melanogenic responsiveness to melanocyte‐stimulating hormone (MSH) varies with cell density in culture. Our objective in this study was to learn more about the intracellular systems involved in the control of melanogenesis, particularly the role played by calcium. The melanogenic response to αMSH was compared to the response to drugs affecting intracellular free calcium and calmodulin over a range of cell densities in B16F1 cells. αMSH‐stimulated melanin production was extremely density‐dependent but αMSH‐stimulated cyclic AMP production was independent of cell density. The melanogenic response to agents that increased intracellular calcium (A23187) or inhibited intracellular calmodulin varied with cell density. A drug (TMB8) that lowered intracellular free calcium, however, increased melanogenesis independently of cell density. At high cell density it was found that an elevation in calcium decreased melanogenesis, whereas agents that reduced calcium or inhibited calmodulin activity increased melanogenesis. At low cell density, however, the inhibitory response to A23187 was lost and in some experiments even stimulated melanogenesis. These data suggest that the calcium/calmodulin signalling system has an inhibitory influence on melanogenesis, and its expression, which depends upon cell density, may also modulate the response to stimulatory agents such as αMSH.
Biological Activities of Melanotropic Peptide Fatty Acid Conjugates
Authors: HADLEY MAC E. , AL‐OBEIDI FAHAD , HRUBY VICTOR J. , WEINRACH JONATHAN C. , FREEDBERG DOUGLAS , JIANG JINWEN , STOVER RACHEL S.
Published: July 2006

Four fatty acids (FA, palmitic, myristic, decanoic, hexanoic) were individually conjugated to the N‐terminus of the α‐MSH fragment analog, H‐Asp5‐His6‐D‐Phe7‐Arg8‐Trp9‐Lys10‐NH2. This resulted in enhanced potency of the conjugates (compared to the unconjugated melanotropin analog) as determined in the lizard skin bioassay and in the mouse melanoma cell tyrosinase bioassay. The shorter conjugates of hexanoic and decanoic acid were at least equipotent to α‐MSH in the lizard skin bioassay, whereas the longer myristoyl and palmitoyl analogs were 100 times less active. The myristoyl and palmitoyl conjugates exhibited a “creeping” potency in the lizard skin bioassay—that is, potency of the peptides increased with time in contact with the skins. These observations may be related to the more lipid nature of these FA‐conjugates. In the tyrosinase assay, the conjugates were 10–100 times more active than α‐MSH or the unconjugated analog. Each of the FA‐melanotropic peptide conjugates exhibited prolonged (residual) melanotropic activity in both the lizard skin and melanoma cell bioassays. In other words, after removal of the melanotropin conjugates from contact with the skins or cells, responses were still manifested for hours or days thereafter. As little as 1 hr of contact with melanoma cells resulted in enhanced enzyme activity as measured 48 hr later. Since the conjugates, but not H‐[Ast5,D‐Phe7,Lys10]α‐MSH5‐10‐NH2, exhibited prolonged activity, the conversion of reversible agonists to irreversible agonists was demonstrated.
A Recombinant Vaccinia Virus Infects Xenopus Melanophores
Authors: Potenza Marc N. , Lerner Michael R.
Published: July 2006

A recombinant vaccinia virus was employed to demonstrate infection of cultured Xenopus laevis melanophores. The recombinant virus contains one copy each of the Escherichia coli lac Z and human growth hormone genes under the transcriptional control of two separate viral promoters. Western blot analysis and in situ staining revealed the dependency of beta‐galactosidase production in infected Xenopus cells on time and multiplicity of infection (MOD. Western blot analysis was used to demonstrate the production of a 65 kD vaccinia late protein and its variation over time and with MOI. When virus preparations from infected Xenopus cells were attempted, no amplification of virus was observed and only a minute portion of the original innoculum was recovered. We therefore propose an abortive infection of Xenopus pigment cells by vaccinia virus: The amphibian cells allow for the synthesis of viral proteins, but not for the efficient replication of competent virus. The findings have implications not only for our understanding of the virus/host interaction, but also for the efficient expression of exogenously introduced genes in cultured Xenopus melanophores.
Truffle Melanogenesis: Correlation With Reproductive Differentiation and Ascocarp Ripening
Authors: RAGNELLI ANNA M. , PACIONI GIOVANI , AIMOLA PIERPAOLO , LANZA BARBARA , MIRANDA MICHELE
Published: July 2006

The present work uses histochemical techniques to investigate the correlation between reproductive differentiation and age of truffles (Tuber aestivumandTuber melanosporum) with melanin synthesis. The dopa oxidase and tyrosine hydroxylase activities of tyrosinase have been localized within the ascocarp and melanin localization was performed by the Schmorl's reaction. A true tyrosinase is present in truffles, able to oxidize both 1‐tyrosine and 1‐dopa. The tyrosinase activity is on in the young ascocarps (in the peridium, hypothecium, and fertile veins) and off in the ripe ones, thus it appears correlated with the age and differentiation of the sporogenic hyphae that arise from the hypothecium; a similar correlation has been previously described inNeurospora crassawhich is an ascomycete as well as the truffles.