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At least 163 records · Page 9Linked to original sources

Coat color genetics of Peromyscus: II. Tan streak--a new recessive mutation in the deer mouse, P. maniculatus.

The first mutant tan streak deer mice appeared in the initial laboratory-bred generation of a stock of Peromyscus maniculatus nubiterrae collected in Macon County, North Carolina. Laboratory progeny from the original animals were bred and mated among themselves and to wild-type individuals. The tan streak phenotype is characterized by nearly complete absence of coat pigmentation, except for a pale tan patch or narrow stripe extending mid-dorsally posteriorly from the head. The band is frequently somewhat broader in the shoulder region, occasionally forming a cross-shaped pattern. There is no evidence of black eumelanin in any part of the coat. The eyes are fully pigmented, appearing black, and pigment is present in the skin of the ears and elsewhere. The trait is inherited as an autosomal recessive. The genetic locus is provisionally designated tns. Crosses between homozygous tan streak (tns/tns) animals and albino (c/c), ivory (i/i), non-agouti (a/a) and brown (b/b) deer mice produced only wild-type progeny, indicating that the tns mutation is not at any of these loci.

Alleles↗

Tanning, protection against sunburn and vitamin D formation with a UV-A 'sun-bed'.

There are many types of sun-beds, sun-benches and sun-panels containing fluorescent tubes which, because of their predominantly UV-A emission, are advertised to the public as a means of obtaining a tan without sunburn. This study reports the effects of a sun-bed on skin colour, on the protection afforded against sunburn, and on vitamin D formation. Side-effects are also recorded. It was shown that the sun-bed emits mainly UV-A but very little UV-B and some tanning occurred in most subjects. However, no correlation was observed between the subjects' stated ability to tan and the degree of pigmentation achieved at the end of the treatment. Most subjects also had itching and erythema, and three had polymorphic light eruption. Although very little UV-B irradiation was present, a significant increase in serum levels of 25-hydroxyvitamin D occurred, and possible explanations of this surprising finding are discussed. While the sun-bed proved popular with the subjects, only a modest tan was achieved and the incidence of side-effects appeared to limit the value of this type of appliance, especially with regard to the prevention of vitamin D deficiency.

25-Hydroxyvitamin D 2↗

Use of UV-A sunbeds for cosmetic tanning.

A survey has been carried out of people using UV-A sunbeds at commercial premises in the U.K. The degree of tan achieved was found to be closely related to the subject's ability to tan in sunlight, and subjects who burnt easily in sunlight were most at risk of developing erythema after using a sunbed. Side-effects, particularly itching, were common. The prevalence of itching, nausea and skin rashes were higher in women taking oral contraceptives than in women on no medication. Although long-term quantitative estimates of the risks of UV-A sunbed use (such as skin ageing and skin cancer) are unknown, it is recommended that individuals who do not tan or tan poorly should be discouraged from using sunbeds.

Adolescent↗

UVA sunbeds: tanning, photoprotection, acute adverse effects and immunological changes.

The effects on 31 normal subjects following exposure to sunbeds containing UVA lamps with minimal UVB emission have been compared in a double-blind study with the effects on nine control subjects of a similar exposure course three times weekly for 4 weeks to sunbeds emitting visible light. On previously untanned areas, all those subjects on active treatment developed a mild tan; in tanned areas they all developed a moderate tan, while all control subjects developed a minimal to mild tan. The mean protection factor against later UVB-induced erythema was 3.2 +/- 0.3 after the active course and 1.6 +/- 0.2 among the controls. Significantly more frequent adverse cutaneous effects for active subjects were pruritus, erythema, freckling, burning sensation, dryness and polymorphic light eruption. Cutaneous Langerhans cell numbers, and blood CD3+ (pan T-cell) and CD4+ (helper T-cell) lymphocyte subsets were reduced in both active and control groups. CD8+ (cytotoxic/suppressor T-cell) counts were similarly but not significantly reduced in both groups. Pityrosporum yeast counts were significantly reduced in both groups. The changes found in both groups seem attributable to small amounts of UVB emission from both active and control lamps.

Adolescent↗

A hazard assessment of artificial tanning units.

As a result of increasing concern over the use of artificial tanning units, many local government recreation departments are phasing out the use of sunbeds on their premises, resulting in some clients switching to high street parlours about which little is known. An Environmental Health survey was conducted in all 32 tanning premises within a local government area (Perth & Kinross, Scotland). A number of significant problems emerged in the private sector. In this group, there was no form of cumulative UV exposure control in 89% of premises and 81% failed to give adequate advice and information to customers. We conducted UV spectral irradiation measurements in 38 tanning units using a double grating spectroradiometer. When a carcinogenic weighting factor was applied to these measurements, it was found that a 10 min exposure in a high intensity stand-up cabinet carried the same carcinogenic risk as approximately 30 min of local (56 degrees North) mid-day summer sunlight or 10 min of Mediterranean sunlight at mid-day. A questionnaire completed by 57 customers revealed a wide pattern of usage; 6 (10%) had more than 20 h exposure in the previous 12 months and 3 (5%) had made regular use of sunbeds for the previous 16 to 20 years. These results indicate that there is a need for continuing public education and surveillance of commercial artificial tanning units.

Beauty Culture↗

A photobiological evaluation of tanning booths.

The use of tanning booths as a substitute for natural sunlight is becoming increasingly popular. However, unless careful attention is paid to proper design and maintenance, the radiation field inside a tanning booth can be highly anisotropic. The use of simple, inexpensive ultraviolet radiation meters to measure dosage can lead to serious overexposure. Since the ultraviolet radiation inside a tanning booth has a greater proportion of short wavelengths (less than 300 nanometers) than natural sunlight, the amount of skin cancer-inducing radiation received for a tan may be twice that received for a natural suntan.

Dose-Response Relationship, Radiation↗

Differences between Brucella antigens involved in indirect hemagglutination tests with normal and tanned red blood cells.

Brucella antigens capable of sensitizing normal and tanned sheep red blood cells for indirect hemagglutination were compared with antigens involved in agglutination, gel diffusion, and immunoelectrophoresis. Hyperimmune rabbit sera, before and after absorption with various antigenic preparations from smooth and rough B. abortus, were used in the tests. Normal erythrocytes could be sensitized with an NaOH-treated ether-water extract (EW-T) of smooth Brucella. Tanned erythrocytes could be sensitized with a water-soluble extract from ultrasonically disrupted smooth or rough Brucella. The EW-T produced a single precipitation band and the water-soluble antigens produce 6 to 23 bands in immunoelectrophoresis with unabsorbed sera. After absorption of antisera with water-soluble extracts from smooth or rough Brucella cells or from smooth or rough cell walls, the hemagglutinins for sensitized tanned erythrocytes and the precipitins for water-soluble antigens were removed. Absorption with living smooth or rough Brucella cells or with EW-T did not remove these antibodies. The precipitins and hemagglutinins for the antigen EW-T, and agglutinins for smooth cells, were absorbed by smooth antigens but not by rough antigens. It appears that the antigens which sensitize tanned erythrocytes and diffuse through agar gels are present in both smooth and rough forms and may be situated in the cytoplasm or in the internal part of the cell wall, whereas the agglutinogen and the antigen which attaches to normal erythrocytes are surface antigens found only on the smooth Brucella cell.

Animals↗

Measurement of erythema and tanning responses in human skin using a tri-stimulus colorimeter.

A 'Minolta Tri-Stimulus Colorimeter II' was evaluated for obtaining objective measurements of early changes in erythema and tanning. The meter showed a subtle, continuous transition between the primary erythematous response and the delayed tanning of skin which was below the visual threshold for detection. Thereafter, the a* (redness) value of the meter showed a significant linear correlation with the dermatologist's perception of erythema while the b* (yellow) value showed a significant correlation with the perception of tanning. This capability of the tri-stimulus colorimeter to simultaneously evaluate the hue and saturation of skin color affords an improved opportunity to quantitate the transition from erythema to tanning without subjective bias.

Adolescent↗

Functional dissection of a neuronal network required for cuticle tanning and wing expansion in Drosophila.

A subset of Drosophila neurons that expresses crustacean cardioactive peptide (CCAP) has been shown previously to make the hormone bursicon, which is required for cuticle tanning and wing expansion after eclosion. Here we present evidence that CCAP-expressing neurons (NCCAP) consist of two functionally distinct groups, one of which releases bursicon into the hemolymph and the other of which regulates its release. The first group, which we call NCCAP-c929, includes 14 bursicon-expressing neurons of the abdominal ganglion that lie within the expression pattern of the enhancer-trap line c929-Gal4. We show that suppression of activity within this group blocks bursicon release into the hemolymph together with tanning and wing expansion. The second group, which we call NCCAP-R, consists of NCCAP neurons outside the c929-Gal4 pattern. Because suppression of synaptic transmission and protein kinase A (PKA) activity throughout NCCAP, but not in NCCAP-c929, also blocks tanning and wing expansion, we conclude that neurotransmission and PKA are required in NCCAP-R to regulate bursicon secretion from NCCAP-c929. Enhancement of electrical activity in NCCAP-R by expression of the bacterial sodium channel NaChBac also blocks tanning and wing expansion and leads to depletion of bursicon from central processes. NaChBac expression in NCCAP-c929 is without effect, suggesting that the abdominal bursicon-secreting neurons are likely to be silent until stimulated to release the hormone. Our results suggest that NCCAP form an interacting neuronal network responsible for the regulation and release of bursicon and suggest a model in which PKA-mediated stimulation of inputs to normally quiescent bursicon-expressing neurons activates release of the hormone.

Animals↗

Increased eumelanin expression and tanning is induced by a superpotent melanotropin [Nle4-D-Phe7]-alpha-MSH in humans.

Seven normal volunteers (six males and one female) with tanning skin types III or IV (Fitzpatrick scale) were given 10 daily subcutaneous injections of a superpotent synthetic analog of alpha-melanocyte stimulating hormone (alpha-MSH) over two weeks. This agent, [Nle4-D-Phe7]alpha-MSH, also called Melanotan-I (MT-I), was administered at a dose of 0.16 mg/kg/day (Monday-Friday), over a two week period. Tanning was measured serially using computerized light reflectance. This regimen induced tanning at 3 of 8 anatomic sites including the face, neck and forearm by comparison of baseline to (1) the end of the daily dosing period, (day 14), and (2) one week later, (day 21). Shave biopsies of the forearm taken at baseline and day 21 were analyzed by high performance liquid chromatography for eumelanin content which was measured as the permanganate oxidation product, pyrrole-2,3,5-tricarboxylic acid or PTCA. Pheomelanin content was measured as the hydroiodic acid digestion product, aminohydroxyphenylalanine (AHP). Eumelanin was also measured in the forehead skin samples of three subjects. The HPLC results show that mean (+/- SD) baseline eumelanin (PTCA) levels in forehead skin (n = 3) averaged 1.38 (+/- 0.87) ng/mg of wet skin tissue weight. Higher mean baseline levels of PTCA were detected in forearm skin (2.06 +/- 0.28 ng/mg wet weight, n = 7). One week after MT-I treatments ended, there was a mean (SD) 49% (+/- 17.6%) increase in forehead skin PTCA levels compared to baseline (P = 0.019, n = 3, by paired sample T-test). The mean (SD) increase in forearm skin PTCA levels was 98% (+/- 25.4%) over the same period (P = 0.003). In contrast, forearm pheomelanin expression following MT-I treatment did not significantly change from baseline. Overall, the MT-I regimen increased the eumelanin: pheomelanin ratio in forearm skin from 51:1 at baseline to 86:1 following MT-I (P = 0.054 by paired sample T-test). These results show that the tanning induced by MT-I in the face and forearm is associated with a significant increase in the eumelanin content of the human skin.

Adult↗

Social predictors of sunscreen and self-tanning product use.

This study investigated social predictors of sunscreen and self-tanning product use among 164 undergraduates. Immediate family members' sunscreen use predicted participants' facial sunscreen use while sunbathing but not their sunscreen use on other areas of the body. In addition, familial support of a tanned appearance was inversely associated with self-tanning product use, whereas romantic partners' support of a tanned appearance was positively associated with this behavior. The results of this study suggest that it may be important to include socially significant others in interventions for reducing the risk of skin cancer in college students.

Adolescent↗

Imbalanced expression of TAN-1 and human Notch4 in endometrial cancers.

The development of cancer is a cellular process that reflects and is partly driven by alterations in cell determination. Mutations in various genes responsible for cell determination have been identified as being oncogenic; however, little is known about the involvement of normal cell fate-determining mechanisms in the oncogenic process. The Notch pathway is an evolutionarily conserved, general cell-interaction mechanism that controls fundamental aspects of cell determination during the development of vertebrates and invertebrates. We have explored the roles of the recently cloned human Notch4 gene, which is a homologue of Drosophila Notch, in endometrial tissue, a cellular environment where cell fate changes take place and neoplastic conditions have been characterized. Northern blot analysis, dot blot analysis, and in situ hybridization were performed on samples of normal endometria at different phases of the menstrual cycle and endometrial cancers. Our results showed that: a) Both human Notch4 and translocation-associated Notch homologue-1 (TAN-1), another human homologue of Drosophila Notch, are expressed in the normal endometrium, mainly in the endometrial glandular cells. b) The level of expression of human Notch4, but not TAN-1, changes during the normal menstrual cycle; i.e., the level of Notch4 expression was significantly lower during the secretory phase than during the proliferative phase. c) Endometrial cancers express a significantly lower level of human Notch4 and a significantly higher level of TAN-1 than normal endometria. These results suggest that human Notch4 and/or TAN-1 are involved in the changes of the endometrium during the menstrual cycle, and also in the development of endometrial cancer.

Adenocarcinoma↗

Production and biological activities of a new antifungal antibiotic, TAN-950 A.

A novel antifungal antibiotic, TAN-950 complex, was isolated from the culture filtrate of Streptomyces platensis A-136 (IFO 14603, FERM BP-1786). The water-soluble amphoteric substances in this complex were purified by chromatography using ion-exchange resins, QAE-Sephadex and adsorptive resins and were designated TAN-950 A and TAN-950 A-E mixture. The molecular formula of TAN-950 A was determined to be C6H7N2O4Na for the sodium salt. This new amino acid antibiotic showed antifungal activity against Candida albicans in vitro and in vivo, and had low toxicity in mice.

Animals↗

TAN-1120, a new anthracycline with potent angiostatic activity.

A potent angiogenesis-inhibitory compound TAN-1120 was found to be produced by a Streptomyces species isolated from a soil sample. The producing organism was characterized as a new subspecies of S. triangulatus and named S. triangulatus subsp. angiostaticus subsp. nov. due to its specific ability to produce the compound. This substance was isolated as a red powder by a combination of organic solvent extraction, silica gel column chromatography and preparative HPLC using an ODS column. Its structure was elucidated by chemical reactions and spectral analyses to be a new baumycin-group anthracycline. Reduction of TAN-1120 gave two compounds, a deoxy derivative and baumycin A1. TAN-1120 showed remarkably potent angiostatic activity in two conventional angiogenesis assay systems in vivo, while doxorubicin and daunomycin had far weaker activity. It strongly inhibited proliferation of vascular endothelial cells did not prevent capillary cord formation in vitro by the endothelial cells on extracellular matrix-coated plates. TAN-1120 is one of the most potent angiostatic agents reported.

3T3 Cells↗

New naphthacenecarboxamide antibiotics, TAN-1518 A and B, have inhibitory activity against mammalian DNA topoisomerase I.

New naphthacenecarboxamide antibiotics, TAN-1518 A and B, were isolated from a culture broth of Streptomyces sp. AL-16012. Their structures were elucidated from their reactions and from spectroscopic analyses. The relaxation of supercoiled pBR322 DNA by calf thymus DNA topoisomerase I was inhibited by these metabolites as potently as by camptothecin. However, the decatenation of kinetoplast DNA by calf thymus DNA topoisomerase II was little affected by these agents. The major metabolite, TAN-1518 A, strongly suppressed the growth of various murine and human tumor cells, inducing apoptosis. Unlike camptothecin, TAN-1518 A did not stimulate cleavable complex formation in the nuclei of CHO-K1 cells and had weak activity in intercalating into DNA strands. This metabolite arrested the growth of human tumor cell lines in G1 phase of the cell cycle. These results suggest that TAN-1518 A and B are novel antitumor agents targeting topoisomerase I.

Animals↗

[Tanning beds: effect on skin cancer risk unclear].

Recent estimations show that over 25% of the Dutch population make regular use of tanning equipment. This use is still increasing, in spite of improving knowledge on the potential hazards of ultraviolet radiation. There are different motivations to use the tanning equipment. Younger women are largely represented in the group of sunbed users. Recent studies have brought the testimony that intermittent sun exposure (e.g. during holidays) is an important risk factor for skin cancer (notably basal cell carcinoma and melanoma). The investigations have not provided convincing evidence on the relation between the use of artificial devices and the development of skin cancer. This is partly caused by the fact that sunbed users are generally very motivated to get a tan. It is therefore difficult to distinguish between the effect of natural sun and of artificial UV radiation. In the Netherlands, the analyses of scientific data provide the basis for recommendations concerning sun exposure and use of sunbeds. There is an effort to provide the general public with qualified, professional information on the responsible way of tanning.

Basal Cell Carcinoma↗

Sun protection practices, knowledge and attitudes to tans among New Zealand adolescents, 1991-1997.

AIMS: To examine change in the self-reported sun protection, knowledge and attitudes to tans amongst fourth form students from 1991 to 1997. METHODS: Questionnaires were mailed to 20 New Zealand secondary schools, where 20 students were randomly selected to participate in each school. RESULTS: The proportions of adolescents who reported getting sunburnt over summer, and sunbathing for the purpose of tanning increased significantly from 1991 to 1997, while there were decreases in the proportions who reported getting a suntan, wearing clothing for sun protection and having heard of melanoma. There was also some evidence of a decrease in the attribution of positive qualities to a tan. CONCLUSIONS: Some positive changes in attitudes to tanning among New Zealand adolescents were present over the 1991-1997 period. Although these changes are promising there was little change in utilisation of sun protection measures, in fact, there was evidence that this had worsened.

Adolescent↗

Induction of skin tanning by subcutaneous administration of a potent synthetic melanotropin.

UNLABELLED: OBJECTIVE--To determine the efficacy of short-term administration of a synthetic analogue of alpha-melanotropin, [Nle4D-Phe7] (NDP)-alpha-melanocyte-stimulating hormone (MSH), in darkening (tanning) human skin. DESIGN--Randomized, placebo-controlled, double-blind clinical trial. SETTING--Clinical research unit of a university medical center. SUBJECTS--Twenty-eight healthy white men with a history of either poor tanning (skin type I or II) or good tanning (skin type III or IV) recruited from advertisements and paid to participate in the study. METHODS--Each subject received 10 subcutaneous injections of either a purified NDP preparation or saline over 12 days. They were followed up for 7 weeks after therapy was completed. All subjects used a high-potency sunscreen during the trial. MAIN OUTCOME MEASURE--Skin darkening was quantified by serial chromaticity measurements prior to, during, and after therapy. RESULTS: -A significant parabolic curve of skin darkening activity was noted in subjects with skin type I or II (P less than .001) and with skin type III or IV (P much less than .001) who were given NDP. No darkening occurred in the subjects who were given a placebo. Peak changes were seen 1 to 3 weeks after therapy was completed. CONCLUSION--Human skin darkens as a response to a synthetic melanotropin given by subcutaneous injection. Skin tanning appears possible without potentially harmful exposure to ultraviolet radiation.

Adult↗