Biomedical subjects

V Levine

Publications and source records attributed to V Levine.

At least 55 records · Page 3Linked to original sources

PubMed1977

Specific refractoriness of adenylate cyclase in skin to epinephrine, prostaglandin E, histamine and AMP.

The cyclic AMP level in pig skin (epidermis) increases markedly after incubation with epinephrine, prostaglandin E, histamine or adenosine 5'-monophosphate. This increase is transient and "spiking" is the consistent response to these four stimulators. The "spiking" is due to a non-responsiveness or refractoriness which develops within minutes and is specific to any one stimulating hormone but not to the others. The addition of inhibitors of protein syntheses did not prevent the development of the refractoriness. Adenylate cyclase and phosphodiesterase activities measured in skin homogenates prepared from skin samples taken before, during and after the "spiking" did not change significantly. The hormone-induced refractoriness in this skin system appears to be due to a specific, localized loss of function of the adenylate cyclase system.

Adenosine Monophosphate↗

PubMed1977

Epidermal adenylate cyclase systems: the retention of hormone responsiveness after enzymatic separation of pure epidermis.

Although it has been shown that keratome-sliced skin contains active adenylate cyclase systems which respond to various hormones and drugs, unequivocal proof that the epidermis contains these hormone-responsive systems is still lacking. We demonstrate in this study that "pure" epidermis obtained after either collagenase or trypsin treatment does contain the hormone-sensitive adenylate cyclase systems.

Adenosine Monophosphate↗

PubMed1977

Epidermal adenylate cyclase: stimulation of the histamine (H2) receptor by tolazoline.

Tolazoline (2-benzyl-2-imidazoline) activated adenylate cyclase in pig epidermal slices resulting in the accumulation of cyclic AMP. This effect was highly potentiated by the addition of the cyclic AMP-phosphodiesterase inhibitor, theophylline. Specific histamine (H2) receptor inhibitors (metiamide and cimetidine) completely blocked the tolazoline activation of adenylate cylase. At low concentrations (10-100 micrometer), a histamine (H1) receptor inhibitor (diphenhydramine) and a beta-adrenergic blocker (propranolol) did not inhibit this effect. The stimulation of cyclic AMP formation by the combination of tolazoline and histamine was about the same as the stimulation by histamine alone (nonadditive), whereas the stimulatory effects by tolazoline and epinephrine were additive. These data suggest that tolazoline, an alpha-adrenergic blocker, also activates adenylate cyclase at the histamine (H2) receptor site which is distinct from the beta-adrenergic receptor site. Another alpha-adrenergic blocker, phentolamine, did not have this effect.

Adenylyl Cyclases↗

PubMed1976

Adenosine and adenine nucleotides stimulation of skin (epidermal) adenylate cyclase.

Adenosine, AMP, ADP and ATP activated adenylate cyclase in pig skin (epidermis) slices resulting in the accumulation of cyclic AMP. This effect was highly potentiated by the addition of the cyclic AMP-phosphodiesterase inhibitor, papaverine. But another inhibitor, theophylline, strongly blocked the activation of adenylate cyclase by adenosine and adenine nucleotides. Theophylline apparently competed with adenosine for the cell surface receptor. Like theophylline, the addition of adenine alone caused no accumulation of cyclic AMP, but it significantly inhibited the stimulatory effect of adenosine. Guanosine, or guanine, cytidine, uridine, or thymidine nucleotides had no effect on the accumulation of cyclic AMP. Among other adenine nucleotides we tested, adenosine 5'-monophosphoramidate, but not adenosine 5'-monosulfate significantly increased cyclic AMP especially with the addition of papaverine. Neither 2'- nor 3'-adenylic acid were effective. Our data indicate that pig epidermis has four specific and independent adenylate cyclase systems for adenosine (and adenine nucleotides), histamine, epinephrine and prostaglandin E.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1976

Histamine (H2) receptor-adenylate cyclase system in pig skin (epidermis).

Histamine activated adenylate cyclase in pig skin (epidermal) slices, resulting in the accumulation of cyclic AMP. This effect was highly potentiated by the addition of cyclic AMP-phosphodiesterase inhibitors (theophylline, papaverine). A specific H2 receptor inhibitor (metiamide) inhibited the effect of histamine completely, while other antihistamines (diphenhydramine, acetophenazine, perphenazine, fluphenazine, promethazine) inhibited the effect of histamine to various lesser degrees. It has been shown that both epinephrine and prostaglandin E stimulate epidermal adenylate cyclase. Our data using specific blocking agents indicate that histamine, epinephrine and prostaglandin E2 act independently on the epidermal adenylate cyclase system.

Adenylyl Cyclases↗

PubMed1976

Multiple forms of cyclic nucleotide phosphodiesterase in pig epidermis.

Pig epidermal cyclic nucleotide phosphodiesterases (EC 3.1.4.16) have been partially purified by DEAE-cellulose column chromatography. At least three different forms of the epidermal phosphodiesterases were identified. They were cyclic GMP-specific, cyclic GMP- and cyclic AMP-hydrolyzing and apparently a cyclic AMP-specific enzyme: the first two forms were soluble and the last was the particulate enzyme. The cyclic GMP-specific soluble fraction had a relatively low Km, the cyclic GMP- and cyclic AMP-hydrolyzing fraction had a high Km for the respective substrates and the third particulate enzyme had both high and low Km values for cyclic AMP. The cyclic GMP-hydrolyzing enzyme was localized almost entirely in the soluble fraction, whereas cyclic AMP-hydrolyzing enzyme was distributed to both soluble and particulate fractions. Thus, our studies show that the multiple forms of pig epidermal enzyme differ distinctly in their substrate affinity, specificity and subcellular distribution.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗

PubMed1976

Effects of short chain alcohols and hydrocarbon compounds on the adenylate cyclase of the skin.

The cyclic AMP content of epidermal slices is increased by incubation with ethanol, the effect of which is dose-dependent from I to 5% concentration in the incubation media. n-Propanol and acetone are also effective at a concentration equimolar to 5% ethanol. Experimental results suggest that this effect of ethanol is due to activation of adenylate cyclase, rather than to the inactivation of cyclic AMP-phosphodiesterase.

1-Propanol↗

PubMed1975

Cyclic AMP and psoriasis.

Evidence that an adenyl cyclase system is present in all mammalian epidermis is reviewed. This adenyl cyclase is stimulated by at least two separate types of chemicals: catecholamines, which act at a beta-adrenergic receptor site, and prostaglandins of the E series, which act at a separate site. In the psoriatic lesion, the response to these stimulators, especially to the catecholamines, is reduced. Despite this lack of response to external agents which elevate cyclic AMP, the concentration of cyclic AMP within the epidermis of the psoriatic lesion is no lower than in noninvolved skin. How cyclic nucleotides act to control cell proliferation and cell differentiation remains unclear.

Adenosine Monophosphate↗

PubMed1975

Micro-determination of cyclic AMP levels in human epidermis, dermis and haif follicles.

In order to study the biological and possible pathological roles of cyclic adenosine 3',5'-monophosphate (cyclic AMP) in the skin, it is mandatory to measure cyclic AMP in 50-100 mug of microdissected epidermis, dermis or appendages. In the present study, we offer a method of extracting cyclic AMP from less than 100 mug of tissue, removing contaminating nucleotides and scaling down Gilman's method to fit the analysis of small amounts of tissue. Cyclic AMP levels in the dermis, epidermis, and hair follicles (bulbs) were approximately 1, 2 and 3-5 pmols/mug dry weight tissue respectively. This procedure is applicable to the measurement of cyclic AMP levels in limited foci of healthy or diseased skin.

Adenine Nucleotides↗

PubMed1975

Cyclic AMP in skin: effects of acute ischaemia.

The cyclic adenosine 3',5'-monophosphate (cyclic AMP) content of pig skin was measured several seconds to minutes after removal of the skin from the body. It increased very rapidly, reached a maximum by 2 min after removal (4 times higher than the initial level), then decreased very slowly. Propranolol injected into the animal before or added after the removal of the skin did not suppress this phenomenon. The practical significance of this finding (increase of cyclic AMP level in skin after ischaemia) is obvious-in order to measure cyclic AMP level in vivo, the sample must be frozen immediately to avoid an 'artificial' increase in cyclic AMP.

Animals↗

PubMed1975

Prostaglandins and cyclic AMP in epidermis. Evidence for the independent action of prostaglandins and adrenaline on the adenyl cyclase system of pig and human epidermis, normal and psoriatic.

Prostaglandins E1 and E2 stimulate cyclic AMP accumulation in pig epidermis and in human epidermis from patients with psoriasis. Prostaglandins A1,A2 and F2alpha are relatively ineffective. The fact that this stimulation is not inhibited by a beta-blocker (propranolol) and that the stimulation by prostaglandin E2 and adrenaline is additive indicates that each drug acts independently on the epidermal adenyl cyclase system. In other words, prostaglandins E1 and E2 act on a site other than the beta-receptor of adenyl cyclase in epidermis. The stimulation by prostaglandins E1 and E2 is not additive; hence they probably act on the same site. Concentrations of prostaglandin E above 3X10(-7) M are effective in causing stimulation. This concentration may be within the physilogical range and the contribution of endogenous prostaglandin levels in the control of intracellular cyclic AMP levels cannot be disregarded.

Adenylyl Cyclases↗

PubMed1975

On the lack of response to catecholamine stimulation by the adenyl cyclase system in psoriatic lesions.

When epidermis from the uninvolved skin of psoriatic patients was incubated for 5 min in Hank's medium containing adrenaline and theophylline, the cyclic AMP level consistently increased 20-30 times over the level observed when adrenaline was not added to the medium. On the other hand, when epidermis from the involved skin of psoriatic patients was incubated under the same experimental conditions, the cyclic AMP level increased only 2-5 times. Even when theophylline, and inhibitor of specific cyclic AMP-phosphodiesterase, was omitted from the medium, a clearly demonstrable difference in sensitivity to adrenaline was evident in normal appearing and lesional psoriatic epidermis. These results indicate a faulty adenyl cyclase system in the involved epidermis of psoriatic lesions rather than a defective degradation process by the specific phosphodiesterase. Since the Km for adrenaline activation of adenyl cyclase was approximately the same in both the uninvolved and the involved epidermis and since the cyclic AMP increase by adrenaline was abolished by the addition of propranolol, the basic nature of the beta-receptor (specifically the binding affinity to adrenaline) in the involved epidermis does not appear to be defective. On the other hand, the finding that the Vmax for adrenaline activation is 10-20 times higher in the uninvolved than in the involved epidermis suggests that the poor response in the involved epidermis may be due to fewer available binding sites for adrenaline in the psoriatic lesion.

Adenylyl Cyclases↗

PubMed1975

The effects of catecholamine and related compounds on the adenyl cyclase system in the epidermis.

The effect of various hormones and drugs on the adenyl cyclase system of pig and human epidermal slices was studied in vitro. Adrenaline and isoproterenol in the presence of theophylline increased the epidermal cyclic AMP level 20-fold in 5 min. Noradrenaline also stimulated cyclic AMP accumulation but to a much lesser degree. The adrenaline stimulation was marked even in the absence of the phosphodiesterase inhibitor, theophylline. Theophylline potentiated the effect of adrenaline at the concentration of 2-10 mM although theophylline alone did not elevate the cyclic AMP level significantly. The Km for adrenaline stimulation of the adenyl cyclase system of pig epidermis was 7-7 X 10(-7) M. A beta-adrenergic antagonist, propranolol, markedly inhibited the adrenaline stimulation while alpha-antagonists, phentolamine or priscoline, showed little effect. The results are in accord with the view that the epidermis possesses an active adenyl cyclase system with beta-adrenergic receptors.

Adenylyl Cyclases↗

PubMed1975

Is the cyclic AMP in psoriatic epidermis low?

A deficiency of epidermal cyclic adenosine 3', 5'-monophosphate (cyclic AMP) has been implicated as the cause of the incomplete differentiation, increased mitosis and increased glycogen concentration which characterize the psoriatic lesion. This communication contains our data on the epidermal concentration of cyclic AMP in the lesional and 'normal' (non-involved) skin of patients with psoriasis. In these studies we have introduced the following improvement in methodology: (1) Local ischaemia in the biopsy specimens was prevented by not giving any injections prior to removal of the tissues and by freezing the tissues prior to removal. (2) The epidermis was microdissected from the dermis prior to cyclic AMP assay as as to give as pure an epidermal specimen as possible. Epidermal cyclic AMP was found to be 20-25% higher in the skin lesion than in the uninvolved skin when compared on a dry weight or protein basis but essentially when compared on the basis of DNA content. Our conclusion is that the cyclic AMP level in the psoriatic lesion is not lower than that in the 'normal' skin and thus these characteristics in psoriatic lesions cannot be related simply to a cyclic AMP deficiency.

Adult↗

PubMed1973