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Biomedical subjects

K M Halprin

Publications and source records attributed to K M Halprin.

At least 19 recordsLinked to original sources
PubMed1988

Cyclosporin A induced augmentation of the beta-adrenergic adenylate cyclase response of pig epidermis.

It has been known that beta-adrenergic adenylate cyclase response is decreased in psoriatic-involved epidermis. Since the immunosuppressive agent, cyclosporin A, is reported to be effective on psoriasis clinically, the effect of cyclosporin A on beta-adrenergic adenylate cyclase response in pig skin was examined in vitro. Therapeutic serum levels of cyclosporin A (100-400 ng/ml) augmented the beta-adrenergic adenylate cyclase response of the epidermis. Highest levels of cyclosporin A (2-20 micrograms/ml) did not have any effect on its response. Both low Km and high Km cyclic AMP phosphodiesterases were not affected by cyclosporin A. Therefore, it is suggested that the clinical efficacy of cyclosporin A on psoriasis can be explained partially by its direct effect on the keratinocyte itself.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1988

Application study of N-hexadecane on pig skin.

Pig skin was treated with N-hexadecane. Epidermal mitoses, epidermal and dermal histopathology, epidermal phospholipase A2 activity were investigated. The most prominent increase of mitoses was found 48 hours after three applications of n-hexadecane. Epidermal and dermal changes were observed mainly at the same time. Phospholipase A2 activity was decreased when increased mitoses and histological changes were seen. This paradoxical movements of the activity of this enzyme has also been reported in regard to psoriasis.

Alkanes↗
PubMed1987

Immunohistochemical study of beta-adrenergic receptors in the psoriatic epidermis using an anti-alprenolol anti-idiotypic antibody.

In order to study the beta-adrenergic receptor-cyclic AMP system in the human skin, we have developed a monoclonal antibody against the receptor binding site in two fusion steps. We produced an anti-alprenolol monoclonal antibody using a hybridoma technique after the immunization of a mouse with alprenolol-BSA conjugate. This antibody was then used to immunize mice, whose splenocytes were used for the second fusion. Colonies were screened by enzyme linked immunosorbent assay (ELISA) using turkey erythrocyte membrane as an antigen. One of the positive colonies was grown in mice to obtain ascites fluids. This antibody showed the ability to compete with [125I]-iodocyanopindolol for the binding to beta-adrenergic receptors of turkey erythrocytes. The binding of the antibody to the turkey erythrocytes was prevented by the existence of the anti-alprenolol antibody and also L-alprenolol. This antibody showed a prominent inhibition of the adrenaline-stimulated adenylate cyclase activity of the turkey erythrocyte membrane. The data indicate that the anti-idiotypic monoclonal antibody against alprenolol binds to the beta-adrenergic receptors and acts like an antagonist. We further studied the localization of the beta-adrenergic receptors with this antibody in the normal human skin as well as in the psoriatic skin using immunohistochemical technique. A prominent decrease of the beta-receptors was observed in the psoriatic epidermis.

Alprenolol↗
PubMed1986

A cell-spreading inhibitor exists in serum and in epidermal basal cells.

A unique monoclonal antibody was obtained by immunizing mice with complement-inactivated fetal bovine serum (FBS). This antibody, named SI-1, stained epidermal basal cells of humans, pig, guinea pig, and rat by an indirect immunofluorescence technique after pretreatment of cryostat sections with alkali buffer (pH 9.6). After dissociating pig epidermal cells by trypsin, the SI-1 antibody stained exclusively and strongly one type of uniquely shaped cells. They were small and hanging-bell or columnar in shape with one convoluted side on the base, consisting of less than 2.8% of the dissociated epidermal cell population. The antigen contained in FBS was partially purified by affinity chromatography using the SI-1 antibody. The affinity-purified antigen inhibited the spreading of PAM cells, a spontaneously transformed murine keratinocyte line, in serum-free medium in a dose-dependent manner at concentrations of 10(-5) to 10 ng/ml. The antigen also inhibited the spreading of trypsinized pig epidermal cells in the range of 10(-2) to 10(3) ng/ml in the presence of 0.05% FBS. Although there have been a few reports indicating that serum inhibited both spreading and attachment, a specific factor in serum has not been purified before. This is, to our knowledge, the first presentation of a cell-spreading inhibitor contained in serum.

Animals↗
PubMed1986

Monoclonal antibodies against epidermal cell surface and dermal-epidermal junction: antigens which may be epidermal cell spreading factors.

Two monoclonal antibodies which reacted with the epidermal cell surface (SF-1) and the dermal-epidermal-junction (SF-2), respectively, were obtained by immunizing mice with partially-purified human epibolin. The corresponding antigens were partially purified from fetal bovine serum by affinity chromatography using these antibodies. SDS-polyacrylamide gel electrophoresis showed that these antigens contained polypeptide components with molecular weights different from that of epibolin (mol. wt. 65,000 daltons); SF-1 antigen had a 68,000 dalton main component, and SF-2 antigen a broad 58,000-61,000 dalton main component. Both of these partially-purified antigens promoted the spreading of dissociated pig epidermal cells. SF-2 antigen also promoted the spreading of Pam cells (a murine keratinocyte line). The results suggest that proteins capable of promoting epidermal cell spreading may be present on the epidermal cell surface and at the dermal-epidermal junction. However, their physiological role in keratinization remains to be elucidated.

Animals↗
PubMed1979

Cyclic GMP System in epidermis: I. Effect of ischemia.

When keratome-sliced pig epidermis was floated on Hank's balanced salt solution, we observed a rapid decrease in the intracellular level of cyclic GMP. A portion of the lost cyclic GMP was detected in the incubation medium. When the epidermis was kept in air at room temperature, the cyclic GMP level also decreased rapidly but to a lesser degree. Incubating the epidermal slice at 37 degrees C in Hank's balanced salt solution with the addition of 3-isobutyl-1-methyl xanthine (IBMX) prevented the decrease. Also, after the cyclic GMP level had fallen, it could be raised to be the in vitro level by the addition of IBMX. Increased amounts of cyclic GMP were detectable in the medium in this case. These data indicate that the decrease in cyclic GMP in ischemic epidermis is due to sudden activation of epidermal cyclic GMP-phosphodiesterase and also in part due to leakage of cyclic GMP extracellularly. In contrast to the rapid decline in the cyclic GMP level, ischemia caused a rapid and transient increase in epidermal cyclic AMP. This confirms previous data by ourselves and by others (Br J Dermatol 92: 249-254, 1975; J Invest Dermatol 68:125-127, 1977). These "ischemic effects" must be avoided in order to measure the "in vivo level" of cyclic nucleotides in epidermis.

1-Methyl-3-isobutylxanthine↗
PubMed1979

A combined alkali extraction--ethidium bromide technique for the measurement of DNA in small pieces of tissue.

Alkaline solutions (0.1--0.5 N NaOH) at elevated temperatures can be used to extract DNA from small pieces of tissue. RNA is destroyed by the treatment. In tissues which have been previously exposed to tritiated thymidine, aliquots from the extracting solution can be used directly for the determination of DNA by ethidium bromide fluorescence and radioactivity in both DNA and the nucleotide pool.

Animals↗
PubMed1978

Epinephrine activation of pig skin adenylate cyclase in vivo and subsequent refractoriness to activation.

Epinephrine injected intradermally activated pig skin adenylate cyclase and increased the epidermal cyclic AMP level in vivo. This biphasic response reached a maximum in 5 min and gradually decreased thereafter. The simultaneous injection of a cyclic AMP phosphodiesterase inhibitor, isobutyl methyl xanthin (IBMX) potentiated the increase. The simultaneous injection of a specific beta-adrenergic receptor inhibitor, propranolol, inhibited this accumulation of cyclic AMP. After the first activation by epinephrine in vivo, there was a marked refractoriness of the skin (epidermal) adenylate cyclase to subsequent epinephrine stimulation vivo and in vitro. This refractoriness was specific for catecholamine stimulation as responses to histamine were normal. Recovery from refractoriness started at 48 hr and was completed at 1 week after the injection of epinephrine.

Adenylyl Cyclases↗
PubMed1978

Cyclic nucleotide-phosphodiesterase in the uninvolved and involved skin of psoriasis.

In the present study we have compared cyclic nucleotide-phosphodiesterase activities and affinity of phosphodiesterase for substrates (Km) in enzyme preparations obtained from the involved and uninvolved skin of psoriatic patients. With crude skin homogenates we consistently obtained two Km values (high and low) for both the involved and uninvolved, and both Km values were nearly identical between the involved and uninvolved. The same conclusion is also drawn from the Km determinations with partially purified preparations. Cyclic AMP-phosphodiesterase activities with crude homogenates showed no statistically significant differences between the involved and the uninvolved skin. However, when cyclic AMP- and cyclic GMP-phosphodiesterase activities were compared with a highly sensitive assay method in "pure" epidermal samples, which were microdissected free from stratum corneum, dermis and skin appendages, the involved skin contained 40% more activity of the low Km enzyme and 100% more of the high Km enzyme of both cyclic AMP- and cyclic GMP-phosphodiesterase. It is suggested that this may be due to a higher proportion of germinative cells in the lesional epidermis.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1978

Cyclic AMP accumulation in psoriatic skin: differential responses to histamine, AMP, and einephrine by the uninvolved and involved epidermis.

Using the uninvolved and involved skin from psoriatic patients, we investigated the effects of histamine and AMP (or adenosine) in vitro on the intracellular cyclic AMP levels. Both agents activated adenylate cyclase of the uninvolved and involved resulting in the accumulation of cyclic AMP. Without a cyclic nucleotide phosphodiesterase (PDE) inhibitor, these responses were biphasic and the maximal accumulation was observed in 5 min. With the PDE inhibitor both responses were markedly potentiated and high levels of cyclic AMP were observed for more than 20 min. The response to histamine by the involved skin was much greater than that by the uninvolved. The degree of the response to adenosine was approximately equal. In accordance with our previous work, the response to epinephrine by the involved skin was much less than that by the uninvolved. Thus adenylate cyclases of involved skin from psoriatic patients exhibit a markedly diminished response to epinephrine while at the same time exhibiting a markedly enhanced response to histamine. This precludes the possibility that the unresponsiveness to epinephrine can be due to a generalized inability of the epidermal psoriatic plaque cell to make a functioning cell membrane.

Adenosine Monophosphate↗
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↗
PubMed1977

Methotrexate uptake by psoriatic epidermis.

Psoriatic epidermis has been shown to be more sensitive to the effects of methotrexate than normal epidermis. One possible explanation for this observation is more rapid active transport of methotrexate into psoriatic cells. This study compares the uptake of methotrexate by normal and psoriatic epidermis and demonstrates the influence of extracellular pH on this process. Methotrexate uptake was not found to be greater in psoriatic epidermis than normal. A possible explanation for this unexpected finding is discussed.

Acid-Base Equilibrium↗