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Labelling index (LI) was determined in the cap, epidermis, cortex and stele over the apical mm of newly emerged, 0.2, 0.5 - 2 and 4 cm long secondary roots of Vicia faba. This parameter increased in each of the tissues investigated as the roots lengthened. These results have been discussed with respect to the onset of meristematic activity in more of less quiescent lateral root primordia about the time they elongate to form secondary roots. LI was also different in the epidermis, corted and stele in roots of any one length. These differences were more evident in the more basal parts of the laterals examined and they increased with root elongation. On the basis of these results and others in the literature, it is suggested that changes in LI reflect one of the initial events taking place at the onset of cell differentiation and that it may be possible to study differentiation by examining cells from comparable parts of lateral roots which are at different stages of development. [ABSTRACT FROM AUTHOR]

The fungal toxin, fusicoccin, induces wilting when applied to uninfected plant material. We have confirmed that fusicoccin stimulates stomatal opening and the entry of potassium into the guard cells. When detached epidermis of Commelina communis is placed in a potassium-free medium containing 10 μM fusicoccin, the stomata open widely and potassium accumulates in the guard cells, demonstrating that sufficient endogenous potassium is available. The failure of stomata to open on isolated epidermis is discussed. It is suggested that the subsidiary cells respond to a wound hormone produced after stripping off the epidermis, the effect of which is to block the normal route taken by potassium as it moves into the guard cells. A physiological role for the subsidiary cells in regulating stomatal movements is thus strongly indicated. Fusicoccin is able to overcome the effect of those environmental factors, darkness and high CO2 concentrations, which normally inhibit stomatal opening. Evidence is presented that, in this case, it must act within the guard cells and not only on the subsidiary cells. The time of exposure to the toxin required for a subsequent opening response of the stomata is very short. Stomata in contact with 10 μM fusicoccin for 1 min open almost as widely as those exposed to the same concentration for 2 h. [ABSTRACT FROM AUTHOR]

The distribution of 3,3',4',5-tetrachlorosalicylanilide (TCSA), 3,4',5-tribromosalicylanilide (TBS). and 4'-monobromosalicylanilide (MBS) in skin following topical application at varying times was investigated in fluorescence microscopy in unfixed frozen sections. Analyses were carried out before and alter removal of ethanol-extractable materials. In normal guinea pigs. TCSA was detectable in the entire epidermis and dermis between 5 min and 7 days or longer after topical application. It was recognized in the horny layer even after 21 days. Fluorescence of TCSA in sections disappeared completely after ethanol extract ion, unless the application sites were irradiated with long-wave UV. When the sites to which TCSA had been applied were irradiated, only TCSA in the horny layer was not extractable with ethanol. Compared with TCSA. TBS did not easily penetrate the skin and revealed granular fluorescence in the horny layer which disappeared after ethanol extraction. Long-wave UV irradiation transformed the fluorescence into a hand-like appearance which was not ethanol-extractable. The fluorescence of MBS was detected even after extraction. In vitro irradiated TCSA and TBS were washed out of application sites with ethanol. [ABSTRACT FROM AUTHOR]

Guinea-pig epidermal cells were grown in vitro after release by gentle trypsin treatment. The cells formed clusters from which DNA-synthesizing cells grew to form confluent cell sheets. Treatment of the cultures with vitamin A acid (VAA) significantly increased cellular attachment in the first hours after seeding. This was followed by a steep rise in DNA synthesis as revealed by autoradiography and liquid scintillation counting. The increase was approximately 6-fold compared to the controls. Cellular out growth was considerably accelerated as shown by cell density counts. The results show that in vitro VAA exhibits potent mitogenic activity. Culturing of postembryonic epidermal cells seems to be greatly facilitated by the use of this compound. [ABSTRACT FROM AUTHOR]

Strains of phage Group 2 staphylococci and cell-free fractions isolated from the same strains induced toxic epidermal necrolysis (TEN) when injected into neonatal mice. Furthermore, adult mice developed TEN in both hairy and glabrous skin following intracutaneous (but not systemic) administration of cell-free fractions. While normal adult mice did not develop TEN after inoculation of cocci, generalized TEN could be produced in adult mice pretreated with systemically injected corticosteriods for 3 weeks. Mice which had survived injections of cell-free fractions as neonates remained susceptible to intracutaneously administered fractions in adulthood. Regardless of the age of the animal and the cause of TEN (cocci or cell-free filtrates), the pathogenesis appeared identical both hitologically and ultrastructurally, i.e., via intercellular cleavage without evidence of cell necrosis. These studies demonstrate that neither maturation nor hair development, as previously proposed, confer cutaneous resistance to TEN. Instead, an extracutaneous factor(s) probably confers resistance to the normal adult mouse. Since similar factors lead to naturally occurring and experimental staphylococcal TEN in adult humans and adult mice, the adult mouse may prove to be a valuable model for the study of factors resulting in staphylococcal TEN in adult human. [ABSTRACT FROM AUTHOR]

Previous observations on suction blisters have indicated that dermal epidermal adherence is of a viscous nature. However, very small pressure differences over the epidermis generally fail to produce blistering even over extended periods of time. This suggests that a second, nonviscous, element is involved in the adherence of epidermis and dermis. In the present study experiments with interrupted suction were performed. Results demonstrate a process of repair, or regeneration of the adherence, operating with a time constant of less than 1 hr. This process of repair may be described mathematically as an elastic component in the adherence, suggesting the involvement of elastic structures. A process of active reattachment originating from the epidermal cells could also account for the observations. We believe that failure of the repair mechanism, followed in turn by rupture of the viscous bond due to small local pressure differences, may he the cause of some types of experimental and clinical blistering. [ABSTRACT FROM AUTHOR]

Concentrations of gold in skin achieved during systemic chrysotherapy inhibited prostaglandin synthesis in vitro, using a sheep vesicular gland dioxygenase system. Two human epidermal enzymes, acid phosphatase and tryptophanyl-tRNA synthetase, were also inhibited by gold in vitro, but at higher concentrations; the latter action was blocked by 2-mercaptoethanol. Antiepithelial antibody titer, and immunoglobulin synthesis as determined by serial herpes simplex complement-fixing antibody titer, were unaffected by gold. Furthermore, gold concentrations in skin did not correlate with the clinical activity of pemphigus. These findings suggest some possible mechanisms of gold action in pemphigus. such as interruption of the inflammatory cycle and inhibition of skin enzymes involved in blister format ion. [ABSTRACT FROM AUTHOR]

Epidermis from shaved CEI mice (7 9 weeks old) in the resting phase of the hair cycle was isolated by first employing a depilatory agent followed by a mild heat treatment of the skin. A method for isolating mouse epidermal chromatin and the subsequent isolation of histones and nonhistone chromosomal proteins is described. The relative proportions of the chromatin components and the ultraviolet absorption spectra were similar to those of chromatin from mouse or rat liver. Electrophoresis of the histones from epidermal chromatin in acidic polyacrylamide gels containing urea revealed a pattern of histones qualitatively similar to that obtained from mouse or rat liver chromatin. The nonhistone chromosomal proteins of mouse epidermis were analyzed on high-resolution sodium dodecyl sulfate (SDS) polyacryl-amide gels. Our preparation of mouse nonhistone chromosomal proteins revealed approximately 30 bands. A comparison of the SDS gel patterns of nonhistone chromosomal proteins from mouse epidermis, mouse liver, and rat liver revealed some similarities especially in the high- and low-molecular-weight regions and several differences in both the high- and middle-molecular-weight regions. [ABSTRACT FROM AUTHOR]

Epithelial cells (keratinocytes) from normal human epidermis show contact inhibition of movement in vitro. Fifteen minutes following collision, cells were fixed and ultrastructural studies of the contact zone were performed. Small, specialized junctions, not resembling desmosomes, were demonstrated linking the cells. Interlocking micro-pseudopodial cytoplasmic processes were also present. Both these structures might provide a means of limitation of cell overlap. [ABSTRACT FROM AUTHOR]

The changes produced in the histologic appearance of mouse epidermis as the result of daily application of a controlled frictional stimulus for periods of up to 35 days were studied. Friction resulted in thickening of the stratum corneum and an increase in the size and number of cells in the stratum granulosum and stratum spinosum. The degree of epidermal thickening was increased by increasing the frictional stimulus, and, after thickening, the epidermis appeared to be resistant to mechanical damage. An approximate steady state in the rate of epidermal cell formation and cell loss was reestablished during the period of daily stimulation and a 2- or 3-fold increase in the rate of passage of cells from the stratum basale to the stratum corneum was estimated. It was concluded that increased rates of cell formation and maturation play an important role in the adaptive response of the epidermis to mechanical stimulation. [ABSTRACT FROM AUTHOR]

A modified method was developed for rapid and continuous isolation of viable epidermal cells from adult mouse skin. Using a special type of trypsination apparatus (trypsinator) it was possible to obtain 3-6. 106 epidermal cells per 30 cm² of depilated back skin. Dye exclusion tests indicated a viability of more than 80%. In suspension the isolated epidermal cells incorporated ³H-thymidine into acid-insoluble material during a 4- to 6-hr period. After plating on plastic culture dishes the cells grew as primary cultures and could be maintained in a proliferative state for 2 months. After 7days in culture the labeling index reached 17% and the mitotic count 0.67, respectively. The epidermal nature of the cultures was characterized by morphologic features and by detection of a tissue-specific membrane antigen on cultivated cells with a heterologous antiepidermal antiserum. Attempts to increase the low plating efficiency and to maintain the initial proliferation rate were not successful. [ABSTRACT FROM AUTHOR]

Specimens of skin were obtained from 25 human fetuses ranging on crown rump length from 47 mm testimated gestational age 61-51 days. They were pulse labeled in vitro for 1 hr with ³H-thymidine and labeling indices determined. The range of epidermal labeling indices extended from 1.4-11.7%. Rank correlation testing indicates that as crown rump length (age) increases, labeling index decrease. The labeling index also varies inversely with stage of keratinization. Similar observations have been made by others for fetal rat epidermis and chick embryo skin. It is proposed that control mechanisms during epidermal development lead to the formation of keratin precursor molecules and the concomitant inhibition of DNA synthesis. [ABSTRACT FROM AUTHOR]

Recent observations and theories implicating long-wave ultraviolet radiation (320-400 nm) as the stimulus for various phenomena in human skin have prompted us to investigate the erythemogenic properties of middle (UV-B) and long (UV-A) wave ultraviolet light combinations. The backs of fair-skinned human volunteers were irradiated with varying doses of UV-A and UV-B to determine the minimal perceptible erythema (MPE) dose in each of these wavelength regions. The subjects then received overlapping suberythemal doses of UV-A and UV-B in each of several sites . When UV-A was held constant and UV-B was varied, the observed breakpoint dose (energy at which MPE was seen in doubly irradiated sites) quantitatively demonstrated an additive phenomenon. When combined energies approach threshold erythema values, the known erythemogenic properties of high-dose UV-A are additive to the subclinical or visible erythema induced by UV-B. [ABSTRACT FROM AUTHOR]

Ribosome fractions were isolated from normal, trypsinized epidermis of CD-1 female mouse skin. About 83%, of the ribosomes are free, and approximately 17% are membrane-bound. Almost all the ribosomes are found in the post-mitochondrial supernatant fraction. Epidermis 4 days after treatment with 3-methylcholanthrene shows a marked proportionate increase in both free and membrane-bound ribosomes. Again almost all the ribosomes are in the post-mitochondrial supernatant fraction. [ABSTRACT FROM AUTHOR]

The lipases (glycerol ester hydrolases, 3.1.1.3) from two cutanious bacteria Corynebacterium acnes (Propionibacterium acnes, Group II) and Staphylococcus epidermidis have been partially purified and characterized to permit the screening of possible enzyme inhibitors. Ultimately one of these inhibitors may be useful in the topical treatment of acne vulgaris. Although these enzymes are similar in function, they are distinctive in their characteristics. The enzymes were partially purified from liquid culture broth by either ultrafiltration or precipitation followed by gel filtration on Sephadex G-100 and chromatography with a cellulose ion exchanger. These enzyme preparations demonstrated their greatest catalytic activity against emulsions of tributyrin > triolein > tricaprylin > trilaurin > tristearin. The patterns of triglyceride hydrolysis by the two lipases, however, was different. The enzyme from S. epidermidis behaved similarly to pancreatic lipase and cleaved the α positions of the triglycerides more rapidly than the β position, producing monoglyceride intermediated. The C. acnes lipase cleaved both positions with equal facility, producing only glycerol and free fatty acids. C. acnes lipase was stable in the acidic pH range between 5.8, while the S. epiermidis lipase was inactivated in that range and stable between pH 7-10. C. acnes lipase was generally more sensitive to enzyme inhibitors and was very effectively inhibited by diisopropylfluorophosphate (DFP) and some of its analogs, S. epidermidis lipase was not acitivity present within comedones removed from acne patients was inhibited 70% by DFP (0.1 mM), suggesting that the major lipase in comedones originates from C. acnes. [ABSTRACT FROM AUTHOR]

The specific activities of the pyrrolidone carboxylic acid (PCA)-forming enzymes, γ glutamyl cyclotransferase, glutamine cyclotransferase, and glutamic acid cyclotransferase and pyrrolidone carboxylyl peptidase, in homogenates of guinea-pig epidermis were 3.05, 0.99. 0.58. and 0.03 μ moles/hr/mg protein, respectively. The pH optimum, apparent Km, and cofactor requirements of these epidermal enzymes were compared with those in liver, kidney, and brain. If the specific activities of the three cyclotransferases reflect their in situ activity, any one of them can account for formation of the high level (186 μ mole/gm) of PCA in guinea-pig epidermis. [ABSTRACT FROM AUTHOR]

Factors related to the formation of epidermal cell columns were investigated in skin sections which had been expanded and stained with fluoresceine-isothiocyanate of prepared for electron microscopy and electron microscopical autoradiography. An analysis was also made of the epidermal proliferative rate in mouse ear and sole and guinea-pig ear. All these methods showed that, in epidermis which is organized into cell columns, the cornification process does not occur synchronously in adjacent stacks. Cornification occurs alternately from one column to the next so that the newest cornified cell is found in the lowermost (down) position, and in consequence there are fewer living cells in this stack. Further flattening. due possibly to the loss of turgidity and cellular contents in the newly cornified cell, apparently results in an overall reduction of pressure in this column. It is then possible for the most mature basal cell to slide from the basal layer and position itself in this column. Evidence for the movement of maturing basal cells in this way was demonstrated by staining with fluoresceine-isothiocyanate. It was also found that column formation was associated with a low rate of new cell production. Where the new cell production exceeds one cell per day per corneocyte, cell production. Where the new cell production exceeds one cell per day per cornepcute, cells of the same age and hence maturity are in competition, and a disorganized arrangement occurs. It is concluded that the low cell production and hence the differences in degree of maturation of neighboring cells in adjacent stacks are directly responsible for the columnar organization of epidermis in certain body sites. [ABSTRACT FROM AUTHOR]

Stratum corneum from Negroes and Caucasians has been compared with respect to facility of tape stripping, numbers of cell layers, and density. Significantly more strips were required for removal of stratum corneum, and significantly more cell layers were present in the stratum corneum from Negroes as compared to Caucasians. The buoyant density of abdominal stratum corneum, as determined in organic solvent systems. is less in Negroes than in Caucasians. The reverse is true when density in air is determined and when isopyknic sucrose density gradient ultracentrifugation is employed. We believe the latter values portray the true relationship of Negro and Caucasian stratum corneum. since detipidization does not occur, and since a greater density of Negro stratum corneum is consonant with its greater microscopic compactness. [ABSTRACT FROM AUTHOR]

Mixed cultures of epidermal and dermal cells from term fetuses of Balb/cAn mice were exposed to high concentrations (50 μg/ml) of 7. 12-dimethylbenz(a)anthracene (DMBA) in medium containing Tween-80 or to medium with Tween-80 alone for 45 min. Within 5 weeks the cultures exposed to DMBA began to exhibit accelerated growth in vitro and an epithelioid morphology. These same changes occurred in the Tween-80-treated group starting around 15 weeks in culture. Both sets of cultures remained epithelioid in appearance and rapidly growing for over 9 months. Injections of cells into syngeneic hosts, beginning approximately 21 weeks after treatment. gave rise to undifferentiated tumors. Animals receiving carcinogen-treated cells had more tumors than those receiving vehicle-treated cells. Ultrastructural studies of the transformed cells in vitro suggested that they were of keratinocyte origin, but DMBA + Tween-80-treated cells were more differentiated than cells treated with Tween-80 alone. 80-100 Å cytofilaments, presumably identical to tonofilaments in vivo, were organized into bundles which traversed both the cellular endoplasm and ectoplasm, either terminating on adherens-like junctional structures, or looping back into the cytoplasm after attaching peripherally to such structures. After transplantation into syngeneic hosts, transformed cells from both groups produced tumors which ultrastructurally resembled anaplastic squamous-cell carcinomas. When highly undifferentiated tumors derived from DMBA + Tween-80-treated cells were recultured, more differentiated features reappeared. This observation indicates an important role for the cellular millieu in the determination of phenotypic expression. [ABSTRACT FROM AUTHOR]

The regulation of glycolysis by phosphofructokinase (PFK) was studied in psoriatic epidermis by measuring the acute changes in the levels of adenosine triphosphate. glucose-6-phosphate plus fructose-6-phosphate, fructose-1 ,6-diphosphate, and lactate after periods of ischemia. In all experiments, acute ischemia caused decreases in the levels of adenosine triphosphate, glucose, and glucuse-6-phosphate plus fructose-6-phosphate, and increases in the levels of fructose-1 ,6-diphosphate and lactate. The rapid depletion of glycolytic intermediates before PFK and the accumulation of those after the enzyme indicate activation of the enzyme by ischemia in psoriatic epidermis. [ABSTRACT FROM AUTHOR]

Newborn mouse skin was separated into dermis and epidermis by four procedures, each of which was found to reduce the ability of both skin components to incorporate 14C-acetate into fatty acids. For comparison, skin was labeled with acetate under the same conditions prior to separation by each method. Distribution of polyunsaturated fatty acids was studied after separation of prelabeled skin by trypsin and collagenase. In epidermis both unlabeled and labeled fatty acids were concentrated in the trypsin-released cell. Results indicated that C22 polyunsaturated fatty acids are possibly not synthesized by skin, except 22:4ω6 which is a dermal product. Collagenase-released cells contain mainly saturated acids. Linoleic acid was the only C18 diene observed. The fatty acid composition of both epidermis and dermis depended on the enzymatic method used. [ABSTRACT FROM AUTHOR]

The proportion of sterols in esterified form increase during stratification and cornification of the fetal and newborn rat whole skin and epidermis. This change cannot e ascribed either to development of alternative biosynthetic pathways favoring formation of sterol esters or to a commensurate increase in cholesterol-fatty acyl transferase. The activity of the latter enzyme, in fact, decreases from day 17 of gestation to 7 days postpartum. The decline in enzymatic activity is not due to the presence of inhibitors or exhaustion of endogenous substrate but may reflect changing proportions of epidermal cells in progressive stages of maturation. It is concluded that the increase in sterol esters is due to the increased availability of free fatty acids and sterols provided by the degradation of intracellular membranes during cornification. [ABSTRACT FROM AUTHOR]

The epidermis of squamate reptiles is generated and shed discontinuously. Multiple cornified strata which are histologically, ultrastructurally, biochemically, biophysically, and developmentally distinct are formed sequentially from cells forced out of the germinal stratum. In order to determine the ultimate destiny of cells generated at different times in the sloughing cycle, the fate of ³H-thymidine-labelled germinal cells from the epidermis of Constrictor constrictor was studied with relation to the times of their synthesis of desoxyribonucleic acid (DNA). All DNA synthesis occurred in the cells of single columnar germinal stratum. The ultimate destiny of the progeny did not depend entirely upon when labelling took place. Daughters of cells undergoing DNA synthesis during the early to mid resting phase became part of the alpha, lacunar, and clear stratum of the outer generation and occasionally of the Oberhautchen of the inner generation. Cells labelled in this portion of the resting phase left the germinal stratum randomly and continued to form part of a thickening alpha stratum during the resting phase. The progeny of cells labelled in the mid to late resting phase ultimately became part of the inner epidermal generation. Those cells undergoing DNA synthesis during the early proliferative stage formed portions of the mesos and alpha strata of the inner generation. the daughters of cells labelled during the late proliferative phase generally remained in the germinal stratum and randomly formed part of the alpha stratum after sloughing. The ultimate fate of a cell depends more on when it leaves the germinal stratum than on when it was generated. Paired daughter cells may form parts of different strats, and cells labelled at the same time may end up in different strata depending upon their position in the scale and when they leave the germinal stratum. These studies support the idea of intrinsic epidermal determination of differentiation squamate epidermal strata [ABSTRACT FROM AUTHOR]

Incorporation of cystine -²H into keratohyalin granules of newborn rat epidermis was studied by autoradiography, Sulfhydryl and disulfide groups were tested both in situ and in isolated keratohyalin granules by the use of the DDD reagent. Labeled granules appeared in significant numbers in skin specimens taken 6 and 24 hr after injection of cystine-³H, indicating that cystine-containing protein had been incorporated. Granules in situ gave a negative test whereas isolated granules gave a positive test with the DDD reagent for both sulfhydryl and disulfide groups. The negative reaction obtained in situ was attributed to blocking of the histochemical reaction rather than to the absence of cystine-containing protein in keratohyalin granules as proposed by previous investigators. [ABSTRACT FROM AUTHOR]

The epidermis of patients with several different types of ichthyosis has been analyzed for the presence of keratohyalin granules, a positive stain for protein-bound histidine, and the incorporation of labeled histidine into protein. It has been shown that when keratohyalin granules are absent there is no increased incorporation of histidine in the upper malpighian layer or increased staining for histidine as is observed in normal epidermis. In a variety of lower vertebrates, kerathohyalin granules are absent and there is no staining for histidine. The absence of keratohyalin granules appears to be associated with a failure to synthesize a histidine-rich protein. [ABSTRACT FROM AUTHOR]

Protein (HRP), rich in histidine and soluble in o.I.N HCIO4 at room temperature, has been obtained from keratohyalin granules (KHG) isolated from the epidermis of the newborn rat by extraction with 1 M phosphate, pH 7.0, followed by dialysis against H2O. HRP constituted about 50 percent of the protein in the isolated KHG which were shown to have staining properties and ultrastructure similar to the in situ KHG. HRP was also obtained from the residual tissue after removal of the KHG. Polyacrylamide disc gel electrophoresis in sodium dodecyl sulfate resolved the total protein of the KHG into 15 separate bands having molecular weights from 12,700 to 93, 000 daltons with highest concentrations of protein at 48,500 and 79,000 daltons. Histidine, aspartic acid, glutamic acid, arginine, serine, threonine, glycine, and alanine constituted 85 percent of the total protein in the KHG. Neither methionine nor cysteine residues were detected. The demonstrated presence of HRP in the KHG makes it possible to investigate molecular phenomena of control in epidermal differentiation. [ABSTRACT FROM AUTHOR]

Under normal conditions the stratum corneum in vivo is very much less hydrated than the excised tissue routinely used in laboratory permeability experiments. As a consequence, certain quantitative predictions of skin permeability based on laboratory experiments are not applicable to many cases of clinical and practical interest. In this study a modified in vitro permeability technique was used which permitted the hydration of the stratum corneum to be maintained very close to its natural state. Penetrant molecules were applied by adding a few microliters of acetone solution to the stratum corneum surface. The acetone quickly evaporated leaving a residue of solid penetrant. The time course of penetration of the solid material through the epidermis was observed as a function of applied dose, mild hydration, and solvent contact time. Remarkably steady, uniform penetration persisting over several weeks was observed. Generally, the penetration rates were similar to those observed in vivo and increased in a similar manner upon occlusion. Diffusion through the stratum corneum rather than sorption of the solid at the surface appears to be rate limiting. [ABSTRACT FROM AUTHOR]

In most animal tissues, lipogenesis converts excessive dietary carbohydrate or protein into storage lipids and this process must obviously be under the control of homeostatic regulatory mechanisms related to dietary intake and composition. The lipids of the skin, both sebaceous and epidermal, however, are formed for a specific biological function, to maintain the integrity of the integument. Lipogenesis, on another hand, in skin regulated by the same mechanisms that operate in other tissues poses a problem.

Glucose, glycoge&ngrave;, and ATP concentrations were measured in the peripheral and central layers of the sebaceous glands as well as in the epidermis. Both carbohydrates exhibited a decreasing gradient of concentration from the periphery to the center of the glands. No differential distribution of ATP content was found in the sebaceous glands. The periphery of the glands contained 8 m moles glucose, 22 m moles glycogen, and 10 m moles ATP per kg dry weight tissue. The glucose and ATP concentrations were comparable to those in epidermis, whereas on the basis of lipid-free dry weight the amount of glycogen at the periphery was 6.3 times that of epidermis. The total NADP concentration in sebaceous glands was 0.5 m moles/kg dry weight, 78 percent of which was in the reduced form; the total NAD concentration was 1.4 m moles/kg dry weight, 34 percent of which was in the reduced state. Sebaceous glands contained 3 times more NADP nucleotides than epidermis. The ratios of the NAD nucleotides to NADP nucleotides were 3:1 in the sebaceous glands and 8:1 in the epidermis. Of the 29 enzymes assayed, the most prominent in the sebaceous glands were α-glycerophosphate dehydrogenase, malic enzyme, alanine amino-transferase, glucose-6-phosphate dehydrogenase, and phosphorylase. Enzyme analyses also demonstrated increased contributions of the pentose phosphate pathway and tricarboxylic acid cycle, a significant role for glycogen metabolism and active glycolysis. The high activities of α-glycerophosphate dehydrogenase and triosephosphate isomerase suggest that triosephosphate is being shifted into α-glycerophosphate for the acylglycerol formation. The high aminotransferase activities suggested an important contribution of amino acid metabolism to the sebaceous glands. The conspicuously high activity of alanine aminotrans-ferase indicates a tissue potential to convert amino acids to pyruvate in sebaceous glands. High malic enzyme and malate dehydrogenase activiti... [ABSTRACT FROM AUTHOR]

The sebaceous glands in man are aggregates of various-sized acini that empty into a duct. Glandular configuration is determined by the relative size of the glands in any given area and the number of other glands in the same area, that is by the amount of crowding they are subjected to and by the nature of the dermis in which they grow. Regardless of differences in size, shape, or position, their cellular morphology and sequence of differentiation are similar but not necessarily identical. Sebaceous differentiation is the orderly synthesis, segregation, and accumulation of lipid droplets which culminate in enlarged, misshapen cells that fragment to form sebum.

Two distinct and separate patterns of epidermal cytoplasmic fluorescence were seen with indirect immunofluorescence on human normal skin cyrostat sections. 1. Upper epidermal cytoplasmic (UEC). This fluorescence was seen only in the upper and middle epidermis. The epidermal cytoplasm fluoresced brightly except for that of the basal cell layer which was negative and contrasted sharply with the rest of the epidermal cytoplasm. No cytoplasmic fluorescence was seen in the dermis. This pattern was found with sera from patients with bullous and nonbuflous diseases. 2. General epidermal cytoptasmic (GEC). This pattern differed from UEC in that the entire epidermis fluoresced equally intensely. Furthermore, strong cytoplasmic fluorescence was noted in the dermis. This pattern was seen in live patients with nonbullous diseases and in one patient with bullous pemphigoid. Cytoplasmic fluorescence was seen on human spleen touch imprints with sera producing both these patterns, but no cytoplasmic fluorescence occurred on human huffy coat peripheral blood smears. [ABSTRACT FROM AUTHOR]

Studies of freshly excised rat skin yield evidence that the living epidermal cells are responsible fur the nonlinear electrical behavior of skin. The electrical measurements were carried out according to the method call "phoreography" developed by J. Kryšpín. It appears that the nonlinearity is closely rehired to the metabolism of the epidermis, in particular to oxidative processes. A tentative interpretation of the mechanisms involved is given in terms of membrane phenomena. [ABSTRACT FROM AUTHOR]

The mitotic response of mouse ear epidermis to a controlled frictional stimulus produced by a rotating brush has been studied. A single application of friction resulted in an increased rate of cell proliferation judged by the number of Colcemid-arrested mitotic nuclei per unit length of epidermis. Maximum mitotic activity was found 48 hr after friction. Mitotic duration was apparently reduced in friction specimens. Daily application of friction for up to 35 days resulted in a high level of mitotic activity throughout the experimental period. The epidermal mitotic response to friction appears to be similar to the response to other forms of physical or chemical trauma. [ABSTRACT FROM AUTHOR]

The value of HL-A antigens as genetic markers and epidemiologic tools in various disease states is becoming increasingly apparent. The antigens of the HL-A system (the major histocompatibility locus in man) are found on most human cells, especially the leukocytes and cells of the epidermis and the dermis. Associations have recently been found for HL-A antigens in psoriasis. atopic dermatitis, systemic lupus ervthematosus, dermatitis herpetiformis, pemphigus vulgaris,. and malignant melanoma of the skin; in several other diseases, associations with HL-A antigens are also probably present. Two possible mechanisms of association of HL-A with various diseases are (1) a close linkage between a gene governing immunologic responsiveness to a disease and HL-A genes, or (2) antigenic (chemical) cross-reaction between HL-A antigens and the etiologic agent (e.g.. streptococci or viral capsular antigen) associated with the disease. [ABSTRACT FROM AUTHOR]

The influence of skin temperature on dermal-epidermal adherence was investigated. The adherence was measured by eliciting suction blisters; blistering time was determined under controlled skin temperature. In the range of skin temperatures investigated (20°-43° C) the adherence decreases continuously with increasing temperature. Adherence is, approximately, an exponential function of temperature; an increase of skin temperature by 10° C decreases blistering time by a factor of about 4. This type of relationship supports the hypothesis that epidermis and dermis are connected by a viscous bond. The strong influence of skin temperature suggests that a high viscosity is involved. [ABSTRACT FROM AUTHOR]

Five male subjects with "dry" skin treated one leg For 6 or 14 nights by plastic film occlusion. The treatment resulted in a marked improvement in the appearance of the skin in four out of five subjects. Following the treatment period, dermatome sections of the treated and control skin were prepared and the stratum corneum was isolated and examined lot its vapor-phase hydration and dehydration kinetics as well as its composition. Occlusion treatment resulted in an increased mass of tissue/cm² without a change in either the tissue thickness or number of cell layers. This increased mass was associated with an increase in both the water-extractable material and the cellular residue (keratin) and a decrease in the either-extractable materials. The occlusion-treated samples showed an increased capacity to absorb water when hydrated at 95% RH for several days. The increased mass of water was lost more slowly during dehydration at 0% RH and 30°C. The results are discussed in terms of their significance to "dry" skin formation in vivo. [ABSTRACT FROM AUTHOR]

During keratinization basal cells differentiate sequentially into spinous, granular, and keratinized cells. One method nf studying keratinization involves separating the tissue into cell types of its component strata and examining them for differences in synthetic activity. Another approach involves analyzing the preparations in order to determine what proteins are present at each stage of differentiation. This study deals with polyacrylamide disc gel electrophoretic analysis of neutral salt soluble proteins obtained from the four cell populations. In the basal, spinous, and granular cell gels there are some 18 electrophoretic hands. Using the most prominent band as reference (R1 53-57). there are eight faster-moving and 10-slower-moving hands. in electrophoretograms of protein from the keratinized cells, on the other hand, only four prominent bands are present and of these two are new. The other hands are present as traces or are lacking. They apparently represent substances which diminish during differentiation or are precursor of new protein. The alteration in soluble protein content in the differentiated as opposed to the undifferentiated cell gels may be utilized to study sequential changes which occur during keratinization. [ABSTRACT FROM AUTHOR]

Thirty-seven foreskin preparations obtained during routine circumcisions were investigated with the combined skin-splitting and dopa techniques. At birth, melanin pigmentation was present in various degrees. The color of the epidermis varied from very dark brown to very pale in this region of the body which had not yet been exposed to visible or to ultraviolet light for any length of time. The topography of the dermoepidermal junction varied from smooth (mostly in the lightly colored samples) to extremely hilly (characteristic for the darker samples). In 15 specimens 45 dark. 5 medium colored, and 5 macroscopically unpigmented), the frequency population of melanocytes was estimated and no significant difference was found in melanocyte number. There was also no statistically significant difference in the melanocyte frequency when we compared the data obtained from newborn foreskin with that from the adult. [ABSTRACT FROM AUTHOR]

The lactate dehydrogenase activity in mouse ear epidermis exposed to monochromatic wavelengths of ultraviolet light was determined. The wavelengths used in this experiment were between 260 and 380 nm at intervals of 20 nm. The exposure energy was 50 millijoules per cm2 for each wavelength. Ultraviolet light exposure caused an immediate increase in enzyme activity, which remained above normal for at Least 3 hr post exposure. The greatest increase in enzyme activity was observed at 280 nm, whereas activity remained close to the normal level at 320 nm. The effect of 8-methoxypsoralen injected intraperitoneally prior to ultraviolet exposure was determined. Lactate dehydrogenase activity was significantly higher in 8-methoxypsoralen-treated mice than in untreated controls. The increase in enzyme activity associated with 8-methoxypsoralen administration was found to be maximal between 320 nm and 340 nm. [ABSTRACT FROM AUTHOR]

Histochemically identifiable amyloid associated with actinic keratosis was studied with the electron microscope. Typical amyloid filaments forming islands identical to collagen strands were found in the upper dermis. Beyond the lesion of actinic keratosis, no amyloid was found. In the healing wound of a previously biopsied lesion, amyloid was regenerated only when the epidermis covered the wound. In such epidermis-covered granulation tissue, electron-dense amorphous substance was initially formed in the upper dermis and amyloid filaments subsequently emerged within it. In both original and regenerated lesions, perivascular spaces were free from amyloid, and actinic elastosis was absent. It was concluded that secondary amyloidosis associated with actinic keratosis is produced by local fibroblastic cells under an abnormal influence of the epidermis. [ABSTRACT FROM AUTHOR]

Scales from patients with psoriasis sehorrheic dermatitis, and pityriasis rubra pilaris characteristically have microvilli on their surface when examined by scanning electron microscopy. The experiments reported here were designed to investigate the relationships between the development of parakeratotic scale, the appearance of the scale with scanning electron microscopy, and the proliferative state of the epidermis producing the scale. The villous pattern appeared in scale taken from areas that had developed a high mitotic index and appeared to be related to the proliferative state of the epidermis as well as to the appearance of parakeratosis. A " ridge" pattern was found in some specimens examined and this was thought to represent an intermediary stage between the normal pattern and the villous pattern of the hyperproliferative epidermis. [ABSTRACT FROM AUTHOR]

The pattern of organization and cellular architecture of the stratum corneum has been examined by silver staining sheets of epidermis and other keratinizing epithelia after separation from the connective tissue by NaBr. Most specimens of epidermis demonstrated an ordered pattern of closely packed polygons formed by the alignment and superimposition of several layers of flattened cells, each of similar outline form, with a small, regular overlap between adjoining cellular units. This pattern was shown to correspond to a columnar pattern of organization as demonstrated by expansion of frozen sections of epidermis. An ordered pattern of organization was not apparent in keratinizing mucosal epithelia or in specialized areas of epidermis such as those of plantar or palmar surfaces. [ABSTRACT FROM AUTHOR]

Following topical treatments of rat dorsal skin with soap solutions (under greatly exaggerated conditions compared with normal usage) to invoke a primary irritation response, keratotome sections of pure epidermis free from sebaceous glands, and dermis free from epidermis were incubated with 11C glycerol, acetate, thymidine, and glucose in order to measure skin metabolism. In the epidermis. DNA synthesis was stimulated soon after treatment, and this was rapidly followed by increased incorporation of both labelled glycerol and acetate into glycerolipids (phospholipids and triglycerides). No such changes were seen in the dermis. Of these altered lipids, the proportion of the total radioactivity incorporated into phospholipids fell drastically, but rose in triglycerides. The frequency of soap treatment was more important than its duration for the development of irritation and changes in liquid synthesis. The activity of the pentose phosphate shunt pathway, as measured by 1-14C- and 6-14C- glucose oxidation was unchanged after soap treatment, as was the synthesis of epidermal fatty acids. The altered glycerolipid metabolism was reversible if the animals were allowed to recover following mild irritation by soap. Cell fractionation and autoradiography suggested that the germinative (stratum basale) cells of the epidermis were the locus of the observed effect, and not the differentiated cells. [ABSTRACT FROM AUTHOR]

Keratohyalin granules of the cheek epidermis, buccal epithelium, and transitional region of newborn rats were fixed by several different procedures and studied by electron microscopy. Keratohyalin granules of epidermis were irregularly shaped, while those of the buccal epithelium appeared round or oval and those of the transitional zone revealed a fibrillar structure. Electron dense homogenous deposits observed at the edge of keratohyalin granules in epidermis were associated with a fibrillar component in the transitional region but were located in the center portion of keratohyalin granules in buccal mucosa. These results seem to document the heterogeneous composition of keratohyalin granules. The morphology of the granules appears to be altered depending upon the amount and manner of combination of each constituent. [ABSTRACT FROM AUTHOR]

Most previous studies of stomatal behavior on isolated epidermis of Commelina communis have been carried out in media of pH 6.5-7.0. In the present investigation we have used a wide range of pH values obtained with several different buffers, and have paid special attention to the response of the epidermis to incubation in media of pH 4.0-5.0. Within this region of pH, all the cells of the epidermis apart from the guard cells were severely damaged, a condition leading to considerably enhanced stomatal openings even in media containing low concentrations (1 mM) or completely lacking inorganic cations. The guard cells appeared to continue to function normally, with stomatal apertures changing in response to light and CO2, and the cells showing the expected solute potential changes and potassium accumulation as opening occurred. The stimulation of opening might, in part, be attributable to the removal of pressure from the surrounding cells. Exposure of epidermis to a pH of 4.5 for 1½ hours proved to be a highly effective method of destroying all the cells apart from the guard cells, which apparently remained fully functional. This is a quick and reliable way of 'isolating' stomata which could prove invaluable in future studies of their physiology and metabolism. A comparison of stomatal responses to solutes in the medium for epidermis with all cells intact and for epidermis with isolated stomata suggests a role for the subsidiary cells in regulating solute entry into the guard cells. [ABSTRACT FROM AUTHOR]

Measurements of apparent osmotic pressures of guard cells in isolated epidermis of Commelina communis indicate a considerable rise (up to 26.3 bars) when KSUP+] ions are added to the incubation medium. This rise in apparent osmotic pressure appears to be the major cause of the stomatal opening that is stimulated by K[SUP+] ions, but reduction in turgor of the epidermal cells, owing to the solutes in the incubation medium, may also contribute to the wide stomatal apertures. Histochemical tests on epidermis taken from leaves with stomata that were closed in darkness, or that were open in light, suggest that K[SUP+] accumulates in guard cells when stomata open in response to light. No movements of K[SUP+] or Na[SUP+] from epidermis to mesophyll could be detected and it is concluded that ion movements associated with changes in guard cell turgor are probably confined to the epidermis in C. communis. Ion uptake (indicated by[SUP86]Rb and [SUP24]Na) into epidermis was stimulated by light but not by a reduction in CO[SUB2] concentration, whereas stomatal apertures were affected by these environmental factors to approximately the same extent. It is tentatively concluded that active transport of monovalent cations into guard cells might explain the CO[SUB2]- independent light responses of stomata, but not their light-independent CO[SUB2 ]responses. [ABSTRACT FROM AUTHOR]

A method to determine the amount of protoporphyrin in epidermis, blood plasma, and blister fluid has been developed. Epidermis was obtained in a simple way by making suction blisters. The protoporphyrin was extracted by a modification of the method of Schwartz, and was determined spectrofluorometrically. Plasma of normal controls contained little or no protoporphyrin. and no protoporphyrin could be demonstrated in blister fluid and epidermis. All patients with erythropoietic protoporphyria had an increased amount of protuporphyrin in the plasma. They all had protoporphyrin in the blister fluid, and in some the protoporphyrin level in the blister fluid was even higher than in the plasma. Only traces of protopurphyrin were found in freshly isolated epidermis. [ABSTRACT FROM AUTHOR]

Fixation or epidermis with osmium zinc iodide (OZI) for 24 hr at room temperature renders keratinosomes (lamellar granules of epidermis), the Golgi region, and mitochondria preferentially impregnated with heavy material while the remainder of the epidermal cell merely shows background staining. OZI fixation intensifies the heavy metal staining of the lamellae and of the envelope of keratinosomes. Extraction of epidermis with hexane prior to fixation with OZI abolishes the intensified impregnation of the lamellae and of the envelope of keratinosomes with the osmium zinc iodide stain. Because hexane theoretically extracts nonpolar lipids only and does not cause tissue disruption, it is suggested that the OZI-positive materials in keratinosomes are largely nonpolar lipids. [ABSTRACT FROM AUTHOR]

Bullae, erosions, red-blue plaques, and macular erythema are commonly found on sites of pressure in patients immobilized for prolonged periods. Coma from drug overdose is the most frequent predisposing event, but the lesions cannot be related to the toxic effects of any specific medication. The cutaneous lesions are a result of pressure-induced ischemia (and anoxia); their histology may include subepidermal bullae and focal necrosis of epidermis, dermis, subcutaneous tissue, and all epidermal appendages. [ABSTRACT FROM AUTHOR]

Most quantitative permeability data on human skin are based on studies in which water was used as the vehicle. Very little is known of the permeability of normal stratum corneum as it exists in vivo where it is considerably less hydrated. Similarly very little is known of the effect of nonaqueous solvents on the skin although they are common vehicles in topical therapy. In this study the permeation rates of a homologous series of primary alcohols (C1-C10) through skin were measured. The alcohols were applied from aqueous solutions and also as the pure liquids. The permeation behavior in the two cases is compared in terms of (1) the transport rates of the alcohols, (2) the distribution equilibrium between the tissue and vehicle, and (3) the damage to the tissue produced by the vehicle. Fick's law was found to hold as an approximation for both the aqueous and the liquid alcohol systems. Using the measured data, which include permeability and diffusion constants and tissue:vehicle partition coefficients, the diffusional resistance offered by epidermis and dermis is accurately apportioned. The overwhelming role of the stratum corneum in both the aqueous and the pure liquid systems is quantitatively confirmed. The effect of the solubility characteristics of different vehicles on skin permeability is discussed. It is shown that with the aid of a few simple principles and a knowledge of the solubility character of the vehicle, the permeation of different substances can be qualitatively predicted. [ABSTRACT FROM AUTHOR]