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PubMed1983

Induction of histidine decarboxylase in mouse tissues by mitogens in vivo.

Various types of mitogenic substances, such as a Escherichia coli lipopolysaccharide (LPS), concanavalin A (Con A), pokeweed mitogen, polyI:polyC (a synthetic double-stranded RNA) and 12-O-tetradecanoylphorbol-13-acetate (a component of croton oil), induced histidine decarboxylase (HDC) in the liver, spleen and lung of mice at 4.5 hr after injection. Other inflammatory agents without mitogenic activity, such as zymosan, carrageenan, glycogen, D-galactosamine and N-acetyl-muramyl-L-alanyl-D-isoglutamine, did not induce the enzyme. Both LPS (a B-cell mitogen) and Con A (a T-cell mitogen) induced HDC also in nude mice that lack T-cells, indicating that T-cells are not required for HDC induction by mitogens. C3H/HeJ mice, which are LPS-low responder mice in various immunological tests, were quite a bit less responsive to LPS also in the HDC induction. These results show that mitogens with different properties can induce HDC as a common characteristic. On the basis of these results, the possible participation of macrophages in the process of HDC induction by mitogens was discussed.

Animals↗

PubMed1992

Antiflammins. Anti-inflammatory activity and effect on human phospholipase A2.

Two anti-inflammatory peptides (antiflammins) corresponding to a high amino acid similarity region between lipocortin I and uteroglobin were tested for their ability to inhibit purified human synovial fluid phospholipase A2 (HSF-PLA2). No inhibitory activity was observed, even at such high concentrations of peptides as 50 microM. When antiflammins were preincubated with the enzyme and/or the substrate, no HSF-PLA2 inhibition was detected. In vivo anti-inflammatory activity of these peptides was evaluated in several experimental models of inflammation induced by carrageenan, croton-oil, oxazolone and Naja naja naja venom phospholipase A2 (PLA2). In contrast to the in vitro results, anti-inflammatory activity was observed in all tests, except when inflammation was induced by snake venom PLA2. Taken together, our results do not support the hypothesis that the in vivo anti-inflammatory effect of antiflammins is directly related to inhibition of PLA2 activity.

Animals↗

PubMed1986

Direct current potential changes of the vagal nuclear area induced by trigeminal stimulation.

To elucidate the mechanism of the Reilly syndrome (irritation syndrome), direct current (DC) potential changes in the medulla oblongata were investigated. Ipsilateral and contralateral trigeminal stimulation induced a DC potential shift above the vagal nuclear area in the medulla. Maxillary and mandibular nerve stimulation showed a summation effect. Continuous stimulation of the tooth pulp cavity by croton oil induced a progressively developed DC shift. DC potential change by trigeminal stimulation was accompanied by the same process of elevation of extracellular potassium concentration. These findings suggest that trigeminal stimulation increases the excitability of vagal nuclear neurons and consequently provokes the Reilly syndrome.

Animals↗

PubMed1988

Classification of GABA receptors in snail neurones.

The present study aimed to elucidate the pharmacological features of GABA receptors on identifiable neurones of Achatina fulica Férussac by testing the effects of GABA analogues, muscimol, (+/-)-baclofen, (-)-beta-hydroxy GABA and those conformationally fixed in either the extended or folded form of carbon chain, such as trans- and cis-isomers of (+/-)-2-(aminomethyl)cyclopropane-1-carboxylic acid [+/-)-cyclo-GABA-extended and (+/-)-cyclo-GABA-folded) and trans-4-amino-crotonic acid (GABA-extended). The giant neurones used were TAN, d-LPeLN, v-VNAN, v-LCDN and RPeNLN. The minimum effective concentrations (MEC) of these compounds to produce hyper- or depolarization of the membrane potentials of the neurones were determined, and the effective potency quotient (EPQ) of each compound vis-à-vis that of GABA was calculated for each neurone. The GABA receptors in these neurones were classified into the muscimol I, muscimol II and baclofen types. The muscimol I (TAN and d-LPeLN) and muscimol II (v-VNAN and v-LCDN) receptors were respectively hyperpolarized and depolarized by GABA and muscimol but were insensitive to (+/-)-baclofen. These muscimol receptors are inferred to accept GABA in an extended form of its carbon chain, since muscimol, conformationally fixed in this form from C-1 to C-4, was quite effective. Muscimol was more potent on the muscimol II receptors (MEC: 3 X 10(-7)-3 X 10(-6) M; EPQ: 30-10) than on the muscimol I type (MEC: 3 X 10(-5)-10(-4) M; EPQ: 1-0.3).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Histamine metabolism in the Arthus reaction.

Histamine metabolism, i.e., concentration of histamine and activities of histamine-degrading enzymes, histamine-N-methyltransferase (HMT), and diamine oxidase (DAO), were examined in the Arthus reaction induced in guinea pig skin. The specific activity of HMT was 44.12 +/- 3.80 pmole/min/mg protein and was about 15 times greater than that of DAO in control specimens. However, HMT activity decreased time dependently to 35% of the control at 3 hr and to 10% 48 hr after the initiation of the reaction. DAO activity increased to 150% till 1 hr followed by a linear decrease to 35% at 6 hr and to 10% at 48 hr. Histamine concentration showed a prominent linear decrease to 15% of the control at 2 hr followed by an increase to about 85% at 6 hr. This biphasic change seemed to be well explained by the dynamic changes in the activities of histamine-degrading enzymes. Such decrease in enzyme activities were not observed in other experimentally induced inflammations including dinitrochlorobenzene allergic and croton oil dermatitis. The addition of tissue extract from the Arthus reaction sites resulted in about 30% inhibition in both of two enzyme activities, suggesting the presence of some inhibitory factor(s) in the reaction sites.

Amine Oxidase (Copper-Containing)↗

PubMed1987

Biogenic amines in the Arthus reaction.

The concentrations of serotonin, tryptamine, dopamine, and tyramine were quantitatively determined in the Arthus reaction, since the activity of histamine-N-methyltransferase (HMT), a major histamine-metabolizing enzyme that had been demonstrated to be inhibited by such biogenic amines in vitro, decreased significantly in the reaction site. The concentrations of serotonin, tryptamine, and dopamine were unchanged in dinitrochlorobenzene allergic and croton oil dermatitis except for a slight increase of tryptamine in the latter. Tyramine was unable to be demonstrated quantitatively in all specimens tested. The concentration of serotonin decreased to about 30% that of the control level until 1 hr, followed by a prominent increase to about two-fold at 6 hr after the initiation of the Arthus reaction accompanying with a concomitant decrease in HMT activity. However, the concentrations of tryptamine and dopamine were rather decreased in the reaction site, and the net decrease of two amines was far greater than the increased amount of serotonin. The decrease in HMT activity is not stoichiometrically well elucidated from these results, and therefore, the presence of other hypothetic inhibitory factors that are increased in the Arthus reaction should be suspected.

Animals↗

PubMed1991

Evidence for and possible mechanisms of non-genotoxic carcinogenesis in mouse skin.

Most chemicals that produce skin cancer are genotoxic by in vitro and in vivo short-term assays and produce a high incidence of skin cancer within a year if optimal doses are applied. If in long-term skin painting studies one or two tumours in 50 mice are observed there is a general consensus that no carcinogenic activity can be claimed and it has been suggested that if up to 10% tumours are induced by irritant substances this could be due to an enhancement of spontaneous tumour incidence. Observations of skin tumour incidences higher than 10% with non-genotoxic substances, usually after a long latent period, is considered to represent evidence for a non-genotoxic mechanism. Examples of such substances include croton oil, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), sodium hydroxide, potassium hydroxide, phenol, dodecylbenzene and petroleum-derived middle distillates. Two distinct mechanisms appear to be involved in the production of tumours by a non-genotoxic substance. The first of these is that seen with the strong promoting agents. These, by binding to and activating protein kinase C, appear to directly stimulate sustained epidermal hyperplasia without severe skin damage. The other appears to involve substances producing severe skin damage either by a direct caustic effect or by cumulative irritancy. These changes give rise to marked epidermal hyperplasia with repeated episodes of regeneration and damage. The tumour induction by both mechanisms probably results from oncogene activation and it is possible that oxidative enzymes from inflammatory cells may be involved in the activation process. Various reasons are given why non-genotoxic carcinogenesis in the skin is considered not to be relevant to man and ways of recognising and avoiding its occurrence in animals studies are recommended.

Animals↗

PubMed1995

A matter of some sensitivity.

The development of sensitive chromatographic and spectroscopic techniques for the isolation and structure determination of natural products has greatly facilitated phytochemical investigations. Chemical investigations of herbarium material have resulted in the isolation of indole, quinoline and isoquinoline alkaloids from a wide number of plants. Examples of novel natural products from higher plants are given and include alkaloids, terpenoids, phenolics and quinones. Some plants investigated have not yielded the types of constituents which would have been predicted from them. Plant tissue cultures provide alternative sources of biologically active compounds and examples investigated include Cinchona, Ailanthus, Brucea and Artemisia for antiprotozoal compounds and Datura for tropane alkaloids. Biological tests are useful for bioassay-guided fractionation of plant extracts and examples of the isolation of a series of natural products with antiprotozoal and cytotoxic activities are given. Chemical and biological investigations into the traditional medicine Dragon's blood (Croton lechleri) from S. America and a Chinese prescription for the treatment of atopic eczema are described. The use of radio-ligand binding assays for the detection of a wide range of biological activities is discussed. Sensitivity of chemical and biological techniques has greatly improved prospects for finding new drug entities from plants and for investigating traditional medicines. Basic phytochemical investigations should continue to be encouraged especially in view of the rapid loss of plant species.

Alkaloids↗

PubMed1986

Topical anti-inflammatory activity of esters of steroid 21-oic acids.

Prednisolone derivatives, methyl 20 alpha- and 20 beta-dihydroprednisolonate and methyl 17,20 alpha- and 17,20 beta-acetonidodihydroprednisolonate have been evaluated for their topical anti-inflammatory activity in the croton oil induced ear edema test. The order of anti-inflammatory potency was prednisolone greater than methyl 17,20 alpha-acetonidodihydroprednisolonate greater than methyl 17,20 beta-acetonidodihydroprednisolonate greater than methyl 20 beta-dihydroprednisolonate greater than methyl 20 alpha-dihydroprednisolonate. This order was paralleled by the compounds' octanol-aqueous partition coefficients. Furthermore, after two consecutive days topical administration of an equipotent anti-inflammatory dose, only prednisolone significantly decreased plasma corticosterone levels and relative thymus weight, while the new steroid derivatives had no effect on these parameters, indicating their lack of systemic side effects.

Administration, Topical↗

PubMed1989

Synthesis and pharmacological evaluation of conjugates of prednisolone and non-steroidal anti-inflammatory agents.

Esters of prednisolone with ibuprofen and indomethacin were prepared by coupling the 21-hydroxy moiety of the glucocorticoid to the carboxylic group of the non-steroidal anti-inflammatory agents. The local and systemic anti-inflammatory activities of the conjugates were evaluated using the cotton pellet granuloma bioassay and their topical activity evaluated by the croton oil-induced ear edema assay, in male Sprague-Dawley rats. The results indicate that these conjugates possess greater local and topical anti-inflammatory activity than prednisolone. In the subacute ear edema bioassay, the conjugates displayed no discernible untoward systemic effects, unlike prednisolone and prednisolone acetate, which elicited significant adverse systemic effects, at equipotent doses. These findings suggest that the chemical coupling of prednisolone and non-steroidal anti-inflammatory agents produced compounds with enhanced anti-inflammatory potencies and reduced systemic toxicities, particularly when administered topically.

Adrenal Glands↗

PubMed1990

In vivo plaque-forming cell suppression by methyl 20 beta-dihydroprednisolonate.

Methyl 20 beta-dihydroprednisolonate, a new local antiinflammatory steroid, and its ester hydrolysis product, 20 beta-dihydroprednisolonic acid, were evaluated for potential immunosuppressive actions as determined by the splenic plaque-forming cell response assay. The parent compound, prednisolone, was used as a comparative agent. All three corticosteroid agents, when administered intraperitoneally or subcutaneously by separate injections given at the same time as antigen, demonstrated significant dose-related suppression of this immunologic parameter. In a croton oil-induced inflammation test (ear challenge in mice), methyl 20 beta-dihydroprednisolonate demonstrated significant antiinflammatory effects, but only in the ear to which it was applied. The comparative drug, prednisolone, significantly reduced inflammation in the ear to which it was applied and in the contralateral ear as well. The methyl ester derivative demonstrated effective antiinflammatory activity when applied topically in the oxazolone delayed-type hypersensitivity test (ear challenge in mice). The results seen in the plaque-forming cell response are in contrast to the generally noted lack of systemic glucocorticoid actions of the steroid acid ester derivatives reported in other studies.

Animals↗

PubMed1978

Granuloma pouch assay. I. Induction of ouabain resistance by MNNG in vivo.

Growth of granulation tissue was induced in rats inside a subcutaneous air pouch by injection of croton oil. Granulation tissue, isolated and cultured in vitro, gave satisfactory and reproducible cloning efficiency of fibroblast-like cells. This experimental model system was used to study the induction of autosomal point mutations in vivo leading to ouabain resistance. For this purpose the mutagen MNNG was administered in the granuloma pouch, and the formation of ouabain-resistant clones was determined in vitro. Various application schedules, expression times in vivo and selective conditions in vitro were evaluated. The highest frequencies of ouabain-resistant clones were found when MNNG was injected into the pouch 24--48 h after induction of granulation tissue, followed by an expression time in vivo of 24--48 h. No ouabain-resistant clones were formed by cells isolated from untreated rats or from animals receiving the highest tolerated doses of MNNG per os or by intraperitoneal injection. The potential usefulness of the granuloma pouch assay for the evaluation of mutagenic and carcinogenic substances in vivo is discussed.

Animals↗

PubMed1980

Granuloma pouch assay. II. Induction of 6-thioguanine resistance by MNNG and benzo[a]pyrene in vivo.

Growth of granulation tissue was initiated with croton oil on the inside of a subcutaneous air pouch, on the back of adult male rats. Two days later, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and benzo[a]pyrene (BP) were applied directly into the pouch in doses ranging from 0.05 to 1.8 mg and from 0.03 to 0.5 mg, resp. The granulation tissue was excised after 48 h. Isolated single cells were checked for their 6-thioguanine resistance in vitro. The influence of cell density during expression time in vitro, of 6-thioguanine concentration and cell density in selective media on the recovery of mutant cells was investigated. The spontaneous mutation frequency was 0.53 x 10(-5). There was a dose-dependent increase in mutation frequencies with both compounds. The frequency was 5 times as high with MNNG as with BP.

Animals↗

PubMedDate not supplied

Attempts to initiate skin tumours in mice in the 2-stage system using 4-chloromethylbiphenyl (4CMB), 4-hydroxymethylbiphenyl (4HMB), and benzyl chloride (BC). Report of the experiment at 10 months.

Groups of T.O. mice (Theiler's Original, derived from Swiss albino mice) were treated topically, with a single dose of 1.0 mg of 4CMB, 4HMB, or BC, or with 0.4 mg benzo[a]pyrene (B[a]P). Twice-weekly promotion of the treated skin area with croton oil was begun 1 week later. At 10 months the skin-tumour incidence in the positive control (B[a]P) was 8/19, with a mean latent period of 20 weeks. Both 4CMB and 4HMB have so far produced 1 papilloma each (1/36 at 40 weeks, and 1/39 at 34 weeks, respectively), while BC has produced none. Further time is required in order to ascertain whether these single papillomas will develop into carcinomas and thereby herald weak initiating activity for 4CMB and 4HMB.

Animals↗

PubMed1991

Dermatopharmacologic investigations of halobetasol propionate in comparison with clobetasol 17-propionate.

Both halobetasol propionate and clobetasol 17-propionate exerted very marked antiinflammatory, antiproliferative, and vasoconstrictive effects during evaluation in a range of dermatopharmacologic models. Halobetasol propionate was distinctly more potent than clobetasol 17-propionate in the ultraviolet-induced dermatitis inhibition assay in guinea pigs and in the rat model of oxazolone-induced late inflammatory reaction. Halobetasol propionate was slightly more potent than clobetasol 17-propionate in inhibiting croton oil-induced ear edema in rats and mice and in the mouse model of oxazolone-induced early inflammatory reaction. In the cotton-pellet granuloma assay in rats and the epidermal hyperplasia inhibition assay in guinea pigs, halobetasol propionate was distinctly superior to clobetasol 17-propionate. There was a trend in favor of halobetasol propionate in the cutaneous vasoconstriction assay performed in volunteers with ethanol solutions of halobetasol propionate and clobetasol 17-propionate. In a further vasoconstriction assay, performed with a 0.05% concentration of both halobetasol propionate and clobetasol 17-propionate in cream and ointment formulations, halobetasol propionate ointment yielded the highest blanching score. In a hypothalamic-pituitary-adrenal axis study in volunteers, effects of 0.05% halobetasol propionate ointment and 0.05% clobetasol 17-propionate ointment on serum cortisol levels were similar. The overall efficacy trends demonstrated in these dermatopharmacologic studies are in agreement with predictions made from corticosteroid structure and activity relationships and the results of two clinical trials comparing halobetasol propionate and clobetasol 17-propionate ointments in the treatment of plaque psoriasis.

Animals↗

PubMed1980

Light scattering from solutions of a semi-flexible polymer and a polyelectrolyte both having sharp molecular weight distributions.

The particle scattering factor in light scattering is determined for poly(tert-butyl crotonate) in n-butyl chloride and also for partially neutralized poly (acrylic acid) in aqueous solution in the presence of added neutral salt (NaBr). The former is a wormlike chain which is extended due to stiffness of the polymer chain, while the latter is extended due to the electrostatic repulsive force which is a kind of excluded volume effect. A clear difference is found between P(theta) of both polymers.

Journal Article↗

PubMed1990

A non-archimedean theory of interaction of chemical compounds with membranes.

The permeability of procaine across axon membranes and the effect of formaldehyde (FA), crotonic aldehyde (CA) and glutaraldehyde (GA) on the compound action potential of frog sciatic nerve was studied by utilizing a non-archimedean (NA) model of the relaxation process. Such models allow a characterization of biosystems exhibiting more than one time scale. Expansions using Laguerre polynomials have been obtained for relaxation functions. The new approach is tested by fitting the model to the experimental data of other authors, and then applying to extract molecular level information from macroscopic data.

Action Potentials↗

PubMed1983

Epstein-Barr virus activation by tung oil, extracts of Aleurites fordii and its diterpene ester 12-O-hexadecanoyl-16-hydroxyphorbol-13-acetate.

During the screening of plant oils for their Epstein-Barr virus (EBV)-activating potency, we found that tung oil possesses an activity comparable to croton oil. Tung oil from various sources and the extracts from its parental plant Aleurites fordii (Chinese tung oil tree), when used in combination with n-butyrate, were shown to efficiently activate EBV persisting in human lymphoblastoid Raji cells (non-producer). The major diterpene ester in the plant extract, 12-O-hexadecanoyl-16-hydroxyphorbol-13-acetate (HHPA), also exerted a similar activity. In producer P3HR-1 cells, both tung oil and HHPA increased the yield of infectious EBV by approximately five-fold. Since tung oil is used for the manufacture of oil paints, varnishes, waterproof substance, anticorrosives and other products, the implication of using such an agent with EBV-activating potency in our daily life is assessed and discussed.

Cells, Cultured↗