The effect of copper on frog skin. The role of sulphydryl groups

1. 1. Cu²⁺ at a concentration of 10⁻⁴ M, when applied to the external side of the frog skin produces an increase in the short-circuit current (I_sc).

2. 2. This effect was studied in skins of Rana temporaria adapted to cold (5°C) and room temperature (20°C), skins of Rana pipiens adapted to cold, and the results compared with those obtained previously with Rana ribibunda.

3. 3. The observed effect is less dependent upon the adaptation to cold than upon the functional state of the skin: skins with low short circuit currents have a bigger response to Cu²⁺ than skins with high I_sc.

4. 4. A species difference cannot be ruled out since skins of Rana ribibunda exhibiting high I_sc give good responses to Cu²⁺.

5. 5. 5,5′-dithiobis(2-nitrobenzoic acid), a sulphydryl-oxidizing reagent, produces an effect similar to that of Cu²⁺, and dithiothreitol an SH-reducing agent, reverses the effect of this ion.

6. 6. Cu²⁺ also induces an increase in the unidirectional K⁺ fluxes and unmasks a net outward potassium flux.

7. 7. The outward K⁺ flux induced by Cu²⁺ is sensitive to ouabain.

8. 8. It is concluded that Cu²⁺ increases the permeability of the external barrier of the frog skin to Na⁺ and K⁺, probably by reacting with SH groups.

Color and morphological characteristics of the skin in people of different racial groups

A complex colorimetric, spectrometric and morphological research of race-dependent differences in skin colour and structure has been carried out. Certain regularities in the quantity, distribution and morphological composition of melanin-containing structures and Hb pigment have been revealed in the Russians, Vietnamese, Angolans and Mulattoes. The study has shown that sex differences in skin color depend on hemoglobin concentration--in people of the Caucasian race; both on melanin and hemoglobin concentration--in people of the Mongolian race and only on melanin concentration--in people of the Negroid race.     

The effect of copper on frog skin: the role of sulphydryl groups.

1. Cu2+ at a concentration of 10-4 M, when applied to the external side of the frog skin produces an increase in the short-circuit current (Isc). 2. This effect was studied in skins of Rana temporaria adapted to cold,(5 degrees C) and room temperature (20 degrees C), skins of Rana pipiens adapted to cold, and the results compared with those obtained previously with Rana ribibunda. 3. The observed effect is less dependent upon the adaptation to cold than upon the functional state of the skin: skins with low short circuit currents have a bigger response to Cu2+ than skins with high Isc. 4. A species difference cannot be ruled out since skins of Rana ribibunda exhibiting high Isc give good responses to Cu2+. 5. 5,5' -dithiobis (2-nitrobenzoic acid), a sulphydryl-oxidizing reagent, produces an effect similar to that of Cu2+, and dithiothreitol an SH-reducing agent, reverses the effect of this ion. 6. Cu2+ also induces an increase in the unidirectional K+ fluxes and unmasks a net outward potassium flux. 7. The outward K+ flux induced by Cu2+ is sensitive to ouabain. 8. It is concluded that Cu2+ increases the permeability of the external barrier of the frog skin to Na+ and K+, probably by reacting with SH groups.     

Journey to the skin

The peripheral axons of vertebrate tactile somatosensory neurons travel long distances from ganglia just outside the central nervous system to the skin. Once in the skin these axons form elaborate terminals whose organization must be regionally patterned to detect and accurately localize different kinds of touch stimuli. This review describes key studies that identified choice points for somatosensory axon growth cones and the extrinsic molecular cues that function at each of those steps. While much has been learned in the past 20 years about the guidance of these axons, there is still much to be learned about how the peripheral axons of different kinds of somatosensory neurons adopt different trajectories and form specific terminal structures.     

Plant functional classifications: from general groups to specific groups based on response to disturbance

Predicting the effects of anthropogenic changes in climate, atmospheric composition and land use on vegetation patterns has been a central concern of recent ecological research. This aim has revived the search for classification schemes that can be to group plant species according to their response to specified environmental factors. One way forward is to adopt a hierarchical classification, where different sets of traits are examined depending on growth form. Also, at the level of interpretation, the environmental context and purpose of functional classifications need to be specified explicitly, so that global generalizations can be made by comparing across environments functional classifications derived from similar methodologies.     

Blood groups of anthropoid apes and their relationship to human blood groups

Affinity between blood groups of man and those of anthropoid apes is reflected not only in similarities or identities of reactions of the red cells with many specific typing reagents, but also in overall structures of some of the main blood group systems defined in man and in apes.Besides specificities of human-type, such as A-B-O, M-N, Rh-Hr, I-i, etc. known to be present on the red cells of various species of apes, specific reagents were produced by iso- or cross-immunization of chimpanzees that detect red cell specificities characteristic for apes only. Some of those specificities were found to be shared by several ape species and to fall into separate blood group systems that are counterparts of the human blood group systems. Recently obtained serological, as well as population data, indicate that the chimpanzee R-C-E-F blood group system is the counterpart of the human Rh-Hr system. Similarly to the Rh-Hr system, it is built around a main antigen, the R^c antigen, to which secondary specificities are attached by means of multiple allelic genes. The R^c is not only the principal factor of the chimpanzee R-C-E-F group system, but also constitutes a direct link with the human Rh-Hr blood group system, since anti-R^c reagents also detect Rh₀ specificity on the human red cells. Another chimpanzee blood group system, the V-A-B-D system, is counterpart of the M-N-S-s system, and is built around the central antigen V^c. the V^c is not only the principal specificity of the chimpanzee V-A-B-D system, but it also constitutes the direct link with the human M-N-S-s system since anti-V^c reagent gives with chimpanzee red cells reactions parralleling those obtained with anti-N lectin (N^v) while in tests with human red cells it detects specificity identical or closely related to the Mi^a specificity.     

Pathways to improving skin regeneration

A significant proportion of the human population suffers from some form of skin disorder, whether it be from burn injury or inherited skin anomalies. The ideal treatment for skin disorders would be to regrow skin tissue from stem cells residing in the individual patient's skin. Locating these adult stem cells and elucidating the molecules involved in orchestrating the production of new skin cells are important steps in devising more-efficient methods of skin production and wound healing via the ex vivo expansion of patient keratinocytes in culture. This review focuses on the structure of the skin, the identification of skin stem cells, and the role of Notch, Wnt and Hedgehog signalling cascades in regulating the fate of epidermal stem cells.     

Relationship between skin response to ultraviolet exposure and skin color type

Sun exposure is responsible for detrimental damage ranging from sunburn to photoaging and skin cancer. This damage is likely to be influenced by constitutive pigmentation. The relationship between ultraviolet (UV) sensitivity and skin color type was analyzed on 42 ex vivo skin samples objectively classified from light to dark skin, based on their values of individual typology angle (ITA) determined by colorimetric parameters. The biologically efficient dose (BED) was determined for each sample by quantifying sunburn cells after exposure to increasing doses of UV solar-simulated radiation. Typical UV-induced biologic markers, other than erythema, such as DNA damage, apoptosis and p53 accumulation, were analyzed. A statistically significant correlation was found between ITA and BED and, ITA and DNA damage. Interestingly, DNA lesions were distributed throughout the whole epidermal layers and the uppermost dermal cells in light, intermediate and tanned skin while they were restricted to suprabasal epidermal layers in brown or dark skin. Our data support, at the cellular level, the relationship between UV sensitivity and skin color type. They emphasize the impact of DNA damage accumulation in basal layer in relation to the prevalence of skin cancer.     

The spatial structure and hierarchy of the ecological groups in the skin microbiocenosis of the breasts

In 120 nulligravidae, 175 pregnant women and 280 puerperants the skin microbiocenosis of mammary glands was studied. Its horizontal structure, the types of the distribution of different ecological groups over the surface of the biotope and their hierarchy, as well as the diversity of species at different anatomical areas, were described. The study showed that the representatives of resident flora were characterized by group distribution, while for transitory flora variations from occasional distribution in nulligravidae to group distribution in nursing mothers were noted. The most pronounced changes in hierarchy were observed in puerperants. In nursing mothers a significant increase in the diversity of species at different anatomical areas were also disclosed.