A study of dermabrasion and chemical peels in an animal model

An animal model was designed to compare the histology of the injuries resulting from dermabrasion and various escharotics presently used for face peeling. The results suggest that dermabrasion, although a superficial wounding process, leads to deep dermal and subcutaneous injuries. The deep dermal wound probably accounts for the correction of actinically damaged skin and wrinkling so often seen after dermabrasion. The injuries after peels were proportional to the concentration of the acid used: 50% phenol being stronger than 50% trichloracetic acid, which is stronger than 25% trichloracetic acid. The effects of epideraml irritants such as croton oil, the effects of occlusion, and the dose-dependent responses of phenol are all presented and discussed.

Complement-independence of the acute-phase production of serum amyloijd P-component (SAP) in mice

Mice depleted of circulating C3 by injection of cobra factor (CoF), the C3-activating protein of cobra (Naja naja) venom, mounted the same acute-phase responses of serum amyloid P-component (SAP) to subsequent injection of casein, bacterial lipopolysaccharide or croton oil as did normal control mice. There was also evidence for accelerated synthesis of C3 itself in response to injection of these acute-phase stimulants in CoF-treated mice. On the other hand complement activation produced by injection of CoF alone did not cause any elevation of the serum SAP level. These results indicate that acute-phase plasma protein production can proceed independently of the complement system as a mediator of or participant in inflammatory reactions, and that complement activation alone is not a sufficient stimulus for an acute-phase response, at least of SAP.

Interaction of benzo [A] pyrene and a hyperplastic agent in epidermal nuclear enlargement in the mouse. A dose response study

Experiments were conducted on the effects of various dose levels of benzo [a]pyrene (BP) on nuclear size in mouse interfollicular epidermis over a 3-day period. Topical application of BP was made with or without croton oil (CO) (0.1 or 0.5%) in the vehicles acetone, toluene and methyl ethyl ketone (MEK). Nuclear size was measured on histological sections either manually or by Quantimet Image Analyser. Vehicle controls treated with 0.1 or 0.5% CO in acetone or MEK gave rise to epidermal hyperplasia with some nuclear enlargement and toluene without CO produced a similar response. It was found that when BP was applied in a vehicle capable of inducing hyperplasia, the nuclear enlargement produced was greater than that produced by either the vehicle control or BP in a non-irritant vehicle. The enhancement of response to BP when tested in the presence of a hyperplastic agent resulted in lower concentrations of BP being detectable. As the levels of BP detectable by nuclear enlargement under these conditions compared reasonably well with those detectable in long-term tests, this system might be usable as a basis for a short-term test for carcinogens.

Promoting action of croton oil on gastrocarcinogenesis by N-methyl-N'-nitro-N-nitrosoguanidine in rats

The promoting effect of croton oil on gastrocarcinogenesis by MNNG was examined in male Wistar rats. Gastric carcinomas were found in five of 10 rats given 83 micrograms/ml MNNG for three months and then 0.02% croton oil with 0.5% Tween 60 as solvent for nine months. No gastric carcinomas were found in rats given MNNG for three months and then Tween 60 only for nine months. The incidence of gastric carcinomas in these two groups was significantly different (p less than 0.05). No tumors were found in rats given only croton oil with Tween 60.

Effect of deoxycholic acid on 7,12-dimethylbenz(a)anthracene-induced, two-stage mouse skin carcinogenesis

The effect of deoxycholic acid on 7,12-dimethylbenz(a)anthracenecroton oil carcinogenesis in mouse skin was tested. Painting deoxycholic acid in addition to croton oil during promotion resulted in the earlier appearance of tumors, a greater tumor incidence, and a larger number of tumors per animal. DMBA initiation followed by either deoxycholic acid or solvents during the promotion period produced no tumors. Animals receiving deoxycholic acid or solvents alone developed no tumors.

Induction of the deficient acid DNAse activity in mouse interfollicular epidermis by croton oil as a possible tumor promoting mechanism

Histochemical activity of acid DNAse, intensity of nucleic acid staining and histological alterations in mouse interfollicular epidermis (I.F.E.) were investigated after a single dose or after chronic topical administration of two hyperplastic agents, of which one (croton oil) was a potent tumor promotor, and the other one (podophyllin) did not promote skin carcinogenesis. Podophyllin induced intense uniform I.F.E. hyperplasia without any proliferation of poorly differentiated basal cells, without increased nucleic acid staining and without any appreciably decreased acid DNAse activity. On the other hand, croton oil (as well as TPA) produced almost immediate, distinct hyperplasia of poorly differentiated basal cells with increased intensity in the staining of both nucleic acids and nearly complete deficiency in acid DNAse activity. Similar histochemical and histological patterns were observed at the sites of wounding hyperplasia in untreated control mice. Such wounding hyperplasia was thought also to be a tumor promoting factor. It was suggested that the decrease in acid DNAse activity which occurred almost immediately after administration of potent tumor promoters and which could not be induced by a hyperplastic agent without tumor promoting action may have a particular importance in the mechanisms of tumor promotion.

Nuclear enlargement and DNA synthesis in mouse epidermis treated with carcinogen and promotor

An autoradiographic investigation was made into the causes of nuclear size increase observed in the mouse epidermis within a few days of topical benzpyrene treatment. The effects of croton oil pretreatment of posttreatment in combination with benzpyrene were examined to see what effect a growth stimulus had on this response. The degree of nuclear size increase induced in the epidermis suggested that some ploidy level increase resulted from combined croton oil and benzpyrene treatment and evidence was found of a G2 block occurring in association with this. Enhancement of nuclear size increase by croton oil highlighted the importance of a growth stimulus in carcinogen induced nuclear enlargement and the implications of this are discussed. Disappearance of enlarged nuclei was seen when mice were kept for 5 days after combined croton oil and benzpyrene treatment in spite of a reduced cell loss compared with croton oil treatment alone.

Passive immunotherapy of established tumors with syngeneic antitumor serum in combination with immunopotentiators

The possibility of passive therapy of 6 approximately 8-day established tumors with syngeneic antitumor antiserum was tested using (1) combination of the antiserum and immunopotentiators, (2) combination of the antiserum and inflammatory agents, and (3) repeated injections of antiserum. Therapeutic effect on an ascites tumor was seen using antiserum in combination with BCG or lipopolysaccharide, or less clearly with carrageenan. Combinations of antiserum and PS-K, histamine, or croton oil did not have a synergistic therapeutic effect, but repeated injection of a small amount of antiserum did have a therapeutic effect on established peritoneal and subcutaneous tumors.

Effects of the water-soluble carcinogen 4-nitroquinoline N-oxide on hamster lingual mucosa

The water-soluble carcinogen 4-nitroquinoline N-oxide (4NQO) was painted onto hamster ventral lingual mucosa twice weekly for up to 20 weeks. No neoplasms developed during this period. The promoting agent croton oil was applied to the treated areas in an attempt to determine whether initiation had occurred. During the following 6 months, one animal developed a papilloma and three animals showed areas of epithelial atypia in the treated mucosa. No malignant neoplasms were seen. Despite its efficiency in producing intraoral neoplasms in the rat, 4NQO would appear to be a poor choice in the hamster.

Effect of tumor promoters on the activity of cyclic adenosine 3':5'-monophosphate-dependent and -independent protein kinases from mouse epidermis

Cyclic adenosine 3'5'-monophosphate (cyclic AMP)-dependent and -independent protein kinases were detected and partially characterized in soluble extracts from mouse epidermis. Cylic AMP-dependent histone kinase activity was separated rom cyclic AMP-independent casein kinase activity by DEAE-Sephadex chromatography. The application of the tumor promoters croton oil or 12-o-tetradecanoyl-phorbol-13-acetate to mouse skin caused a rapid increase in the soluble protein extractable from the epidermis resulting in a decrease in the specific activity of both classes of protein kinase when expressed on a protein basis. No change in the activities of either the cyclic AMP-dependent or -independent enzymes was observed when expressed relative to the DNA content.

Effect of trichloropropene oxide on the ability of polyaromatic hydrocarbons and their "K-region" oxides to initiate skin tumors in mice and to bind to DNA in vitro

The potent epoxide hydrase inhibitor, 1,1,1-trichloro-2,3-propene oxide (TCPO), enhanced the tumor-initiating ability of benzo[alpha]pyrene (BP) and 3-methylcholanthrene (MCA) but had no effect on 9,10-dimethyl-1,2-anthracene (DMBA) initiation in a two-stage system of tumorigenesis in female Charles River CD-1 mice. The tumor-initiating ability of dibenz[alpha,h]-anthracene (DBA) was decreased by prior topical treatment with 10 mumoles of TCPO. The tumor latency period of BP and MCA was decreased by TCPO but had no effect on DMBA or DBA. Topical treatment with 10 mumoles of TCPO did not initiate tumors in a two-stage system in mouse skin nor did it cause any histopathologic changes in the skin. The "K-region" epoxides of BP, DMBA, and MCA were weak tumor initiators when compared to the parent compounds. TCPO only slightly increased or had no effect on the tumor-initiating activity of the above epoxides. Pretreatment with Croton oil 18 hours prior to initiation with BP-4,5-epoxide also slightly enhanced the tumorigenic response in mouse skin. DBA-5,6-epoxide, when tested as a complete carcinogen at high doses (1 mg daily/10 days), was found to be a weak carcinogen but with activity comparable to that of DBA. TCPO only slightly increased the in vitro epidermally mediated covalent binding of the above parent polycyclic hydrocarbons to DNA.

Serum corticosterone as a quantitative test of the phlogistic potency of various agents topically applied in the rat

The application into the rat conjunctiva of various phlogistic agents, such as croton oil, mustard oil and formaldehyde, elicits an increase of serum corticosterone linearly related to the log of the applied concentrations, so that from their parallelized regression lines it is possible to calculate the phlogistic potency of each tested agent in reference to croton oil. The time kinetic of such an increase (elicited by croton oil) is compared with that of two other parameters previously adopted as indirect quantitative indices of the phlogosis: the adrenal ascorbic acid depletion and the liver tyrosine-alpha-ketoglutarate transaminase increase. Serum corticosterone is shown to be the quickest and the most sensitive of the adopted indices, even if the phlogistic potency of the tested agents and the precision of these evaluations substantially coincides whatsoever the index adopted. Finally the pathways of adrenocortical activation are investigated and it is shown that the activation may be peripherally blocked by topical application of corticosteroids (but not of local anesthetics) and centrally by hypophysectomy or parenteral administration of pentobarbital plus morphine.

Effects of croton oil on epidermal growth regulators (chalones)

Variations in epidermal chalones after a single surface application of methylcholanthrene have been described in previous papers. This paper reports a study of the effect of croton oil on epidermal growth regulators (G1 and G2 chalones). Hairless mice received a single topical application of 0.2 ml 0.25% acetone solution of croton oil. Control mice received only acetone. The short-term effect of croton oil on epidermal DNA synthesis and mitotic rate was studied. Other groups of croton oil-treated and acetone-treated mice were then killed at similar time intervals, and the treated area of skin was homogenized and extracted with water. The inhibitory effect of these extracts on normal epidermal DNA synthesis and mitotic rate was assayed in normal hairless mice. The resulting inhibition was interpreted as an expression of the concentration of G1 and G2 chalones, respectively, in the skin extracts. The first experiment confirmed that a single croton oil application provokes a short block in epidermal mitotic activity and probably also in DNA synthesis. This was followed by bimodal peaks of increased activity, the two maxima of mitotic rate on days 2 and 7. The concentration of the two chalones in the skins of treated animals varied in inverse proportion to the alterations in the DNA synthesis and the mitotic rate, with one exception. There was here initially a depression both of the mitotic rate and a low concentration of G2 chalone. This was interpreted as a short, initial direct effect of croton oil on the G2 chalone present at the time of application. It is concluded that croton oil application injures and kills epidermal cells, with subsequent alterations in the content of G1 and G2 chalones. This theory may explain the changes observed. The effects of croton oil on the amount of G1 and G2 chalones in the skin are probably related to the direct, toxic, cell-killing effect of croton oil, and not to its specific cancer promoting potency.

Localization of adenosine o',5'-monophosphate in mouse epidermis by immunofluorescence

Adenosine 3',5'-monophosphate (cyclic AMP) has been localized in mouse epidermal cells using an immunofluorescent technique. Within 10 min following the intraperitoneal injection of isoproterenol or 30 hr following the topical application of croton oil in acetone, staining was clearly visible in the cytoplasm of the basal cells.

Carcinogenesis by carbamic acid esters and their binding to DNA

The tumor-initiating potency of three simple alkyl carbamates and mono-N-substituted ethyl carbamates was examined in Hall strain mice. The binding of 14C-labeled carbamates of DNA was measured in Crackenbush mice. Ethyl carbamate was the most potent carcinogen for the epidermis, liver, and lung, followed by its N-alkyl derivatives. Methyl carbamate was without effect but n-propyl and n-butyl were possible carcinogens. The ethyl esters bound to a greater extent to DNA in liver and skin than the methyl, n-propyl, and n-butyl esters and only this binding persisted. A preliminary application of croton oil increased the yield of skin tumors but not of liver or lung tumors. It also increased the binding of the alkyl carbamates to DNA in skin, the increase being greatest with ethyl carbamate. The binding persisted longer in treated than in non-croton oil-treated mice.

Croton oil- and benzo(a)pyrene-induced changes in cyclic adenosine 3':5'-monophosphate and cyclic guanosine 3':5'-monophosphate phosphodiesterase activities in mouse epidermis

The topical application of croton oil, benzo(a)pyrene, acetic acid, and 12-O-tetradecanoyl-phorbol-13-acetate to mouse skin caused an increase in the activity of epidermal low-affinity cyclic adenosine 3':5'-monophosphate (cyclic AMP) phosphodiesterase. The increase was most pronounced with croton oil, began between 4 and 6 hr after application of this material, and was maintained for at least 48 hr. The activity of cyclic guanosine 3':5'-monophosphate phosphodiesterase was also increased by treatment with croton oil or 12-O-tetradecanoyl-phorbol-13-acetate, but detailed time courses were not obtained. Increased activity was observed in both the soluble fractions and the washed particulate fractions of epidermis. Fractionation of soluble extracts from acetone-treated epidermis on DEAE-cellulose columns showed the presence of enzymes with specificity for both cyclic AMP and cyclic guanosine 3':5'-monophosphate, together with a peak catalyzing the hydrolysis of both cyclic AMP and cyclic guanosine 3':5'-monophosphate. The activity of this latter nonspecific activity was selectively increased following treatment with croton oil. The increase in cyclic AMP phosphodiesterase activity was partially abolished by multiple injections of cycloheximide, suggesting that new protein synthesis was involved. Injection of the alpha-receptor antagonist phentolamine abolished a croton oil-induced rise in epidermal cyclic AMP levels and decreased the induction of cyclic AMP phosphodiesterase activity. From these results it was concluded that the increase in enzyme activity was induced by cyclic AMP.

Initiation-promotion skin carcinogenesis and immunological competence

The immune competence of mice during initiation-promotion skin carcinogenesis was determined by skin allograft rejection and lymphocyte mitogenesis. The carcinogen 7, 12-dimethylbenzanthracene inhibited the cellular immune competence of mice while lymphocytes from croton oil treated mice had enhanced PWM response. Chlorphenesin, a stimulator of cellular immunity, was found to inhibit tumorigenesis in initiation-promotion skin carcinogenesis when injected during promotion.

Acetic acid, a potent stimulator of mouse epidermal macromolecular synthesis and hyperplasia but with weak tumor-promoting ability

The effects of a single application of various dose levels of acetic acid or the weak tumor promoter, phorbol-12,13-ditetradecanoate, on the incorporation of tritiated thymidine (3H-TDR), 3H-cytidine, and 3H-leucine into DNA, RNA, and protein of mouse epidermis, respectively, were determined and compared with histologic changes in the skin. Treatment with either 500 or 833 mumoles acetic acid induced a sequential and sustained stimulation of RNA, protein, and DNA synthesis, which was followed by extensive epidermal hyperplasia similar to that reported for the strong promoter and irritant, 12-O-tetradecanoyl-phorbol-13-acetate. A dose-response relationship between the amount of acetic acid and the rate of DNA synthesis was found between the dose levels of 33 to 833 mumoles of acetic acid per application. The latter dose induced the maximum activation of 3H-TDR into DNA at 723% of control at 2 days, whereas 33 mumoles stimulated DNA synthesis earlier and peaked at 210% of control at 3 hours. Phorbol-12,13-ditetradecanoate also stimulated macromolecular synthesis in a similar sequence, though to a lesser degree. No observable inflammation and only a slight hyperplastic response were noted with phorbol-12,13-ditetradecanoate. Weekly applications of 667 mumoles of acetic acid produced a maximal tumor response of 0.73 papilloma/mouse after 32 weeks of promotion. However, a weekly dose of 677 mumoles of acetic acid was essentially inactive when given in two divided doses. When croton oil was administered twice weekly at a 0.25%-dose level, 10.2 papillomas/mouse were induced after 32 weeks of promotion. The results showed that the previously considered nonpromoting inflammatory agent, acetic acid, must be a weak promoter. However, there was no correlation between stimulated macromolecular synthesis or hyperplasia and tumor promotion when phorbol esters were compared with acetic acid.