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Biomedical subjects

E A Lerner

Publications and source records attributed to E A Lerner.

At least 19 recordsLinked to original sources
PubMed2000

Chrysoptin is a potent glycoprotein IIb/IIIa fibrinogen receptor antagonist present in salivary gland extracts of the deerfly.

Salivary gland lysates of the deerfly (genus Chrysops) contain chrysoptin, an inhibitor of ADP-induced platelet aggregation, which presumably assists the fly in obtaining a blood meal. Chrysoptin has now been isolated, and its cDNA has been cloned and expressed. Chrysoptin was purified to homogeneity using anion exchange and hydrophobic interaction chromatography and found to be a protein with a molecular mass of 65 kDa as determined by gel electrophoresis. N-terminal amino acid sequencing allowed for the synthesis of degenerate oligonucleotides that led to cloning, from salivary gland specific mRNA, of the cDNA encoding this platelet inhibitor. No RGD sites are present in the predicted sequence. A search of GenBank(TM) did not reveal significant sequence homology between chrysoptin and other proteins. The molecular mass predicted from the cDNA was 59 kDa. Predicted glycosylation and phosphorylation sites may account for this difference in molecular mass, as recombinant chrysoptin expressed in Sf21 cells had a molecular mass of 65 kDa, matching that of the natural protein. Chrysoptin functions by inhibiting the binding of fibrinogen to the fibrinogen/glycoprotein IIb/IIIa receptor on platelets with an IC(50) of 95 pmol. These results reveal that insect salivary glands are a source of fibrinogen receptor antagonists.

Adenosine Diphosphate↗
PubMed2000

Characterization of trichotillomania. A phenomenological model with clinical relevance to obsessive-compulsive spectrum disorders.

Multiple approaches to characterization of TTM have been developed, including categoric definitions and dimensional considerations. When TTM is viewed in the context of other disorders with common comorbidities and overlapping similar phenomenologies, such as OCD, body dysmorphic disorder, skin picking, TS, and olfactory reference syndrome, clinical approaches to assessment and differential diagnosis are more complex. This article presents a general overview of TTM included as a background for a heuristic clinical framework for assessing obsessive-compulsive spectrum disorders. A comprehensive behavioral model of TTM as a template is presented in the context of a broader, phenomenologic approach to assessment of several other disorders. These additional conditions were chosen on clinical grounds because they seem to share some phenomenologic characteristics with TTM. It is hoped that combining a phenomenologic approach to the differentiation of repetitive behaviors (as has been valuable in advancing the understanding of repetitive behaviors in TS and OCD), coupled with a paradigmatic comprehensive behavioral assessment and treatment model of TTM, may foster the validation of such approaches for other putative obsessive-compulsive spectrum disorders. Also, the relative intensity and frequency ascribed to the various behavioral and phenomenologic components of the conditions depicted represent clinical impressions, with varying degrees of empiric support, and require objective validation. This approach is meant to serve as a point of departure for clinical assessment of these complex, interesting, and sometimes incompletely diagnosed and inadequately treated conditions. It is hoped that empiric validation or refutation of this conceptualization will stimulate additional research and provide clinicians with a general framework for assessing patients suffering from these difficult conditions. For more information about trichotillomania, contact The Trichotillomania Learning Center (TLC), 1215 Mission Street, Santa Cruz, CA 95060 (831-457-1004; www.trich.org).

Animals↗
PubMed2000

Nitric oxide synthase in toxic epidermal necrolysis and Stevens-Johnson syndrome.

Toxic epidermal necrolysis and Stevens-Johnson syndrome are severe cutaneous drug reactions of unknown mechanism. Nitric oxide can cause apoptosis and necrosis. The inducible form of nitric oxide synthase generates large amounts of nitric oxide and has been described in human skin. We propose that a large burst of nitric oxide in toxic epidermal necrolysis and Stevens-Johnson syndrome may cause the epidermal apoptosis and necrosis. Skin biopsies were taken from seven patients with actively progressing Stevens-Johnson syndrome or toxic epidermal necrolysis. Expression of inducible nitric oxide synthase was examined by reverse transcription-polymerase chain reaction and by immunoperoxidase staining for inducible nitric oxide synthase protein. Messenger RNA for inducible nitric oxide synthase was detected by reverse transcription-polymerase chain reaction and confirmed by the sequencing of polymerase chain reaction products. Strong staining for inducible nitric oxide synthase was observed in inflammatory cells in the lower epidermis and upper dermis. Diffuse, weaker staining was observed in keratinocytes. Expression of inducible nitric oxide synthase is consistent with the hypothesis that nitric oxide mediates the epidermal necrosis in toxic epidermal necrolysis and provides a potential target for therapeutic intervention.

Adult↗
PubMed1999

Functional characterization of structural alterations in the sequence of the vasodilatory peptide maxadilan yields a pituitary adenylate cyclase-activating peptide type 1 receptor-specific antagonist.

Maxadilan is a vasodilatory peptide derived from sand flies that is an agonist at the pituitary adenylate cyclase-activating peptide (PACAP) type 1 receptor. Surprisingly, maxadilan does not share significant sequence homology with PACAP. To examine the relationship between structure and activity of maxadilan, several amino acid substitutions and deletions were made in the peptide. These peptides were examined in vitro for binding to crude membranes derived from rabbit brain, a tissue that expresses PACAP type 1 receptors; and induction of cAMP was determined in PC12 cells, a line that expresses these receptors. The peptides were examined in vivo for their ability to induce erythema in rabbit skin. Substitution of the individual cysteines at positions 1 and 5 or deletion of this ring structure had little effect on activity. Substitution of either cysteine at position 14 or 51 eliminated activity. Deletion of the 19 amino acids between positions 24 and 42 resulted in a peptide with binding, but no functional activity. The capacity of this deletion mutant to interact with COS cells transfected with the PACAP type 1 receptor revealed that this peptide was a specific antagonist to the PACAP type 1 receptor.

Amino Acid Sequence↗
PubMed1999

Maxadilan interacts with receptors for pituitary adenylyl cyclase activating peptide in human SH-SY5Y and SK-N-MC neuroblastoma cells.

Receptors for pituitary adenylyl cyclase activating peptide (PACAP) have been identified in human SH-SY5Y neuroblastoma cells with PACAP being 1000-fold more potent than vasoactive intestinal peptide (VIP) in [(125)I]PACAP binding inhibition and stimulation of cAMP accumulation. Maxadilan, a vasodilator peptide from the salivary gland of the sand fly Lutzomyia longipalpis also specifically bound to SH-SY5Y cells, and was equipotent to PACAP in [(125)I]PACAP and [(125)I]maxadilan binding inhibition, and stimulation of cAMP accumulation. Maxadilan and PACAP also increased the cytosolic free calcium concentration. In human SK-N-MC neuroblastoma cells PACAP, VIP and maxadilan equipotently stimulated cAMP accumulation. The maximal effects of VIP and maxadilan were additive and reached those of PACAP alone. In human T47D breast carcinoma cells PACAP and VIP were also equipotent in the stimulation of cAMP accumulation, but maxadilan was inactive. The results are consistent with the interaction of maxadilan with PACAP specific PAC(1)receptors in SH-SY5Y cells, but not with VPAC receptors, not differentiating between VIP and PACAP in T47D cells. Moreover, maxadilan is a PAC(1)receptor specific agonist which allows discrimination of co-expressed PAC(1)and VPAC receptors in SK-N-MC cells.

Binding, Competitive↗
PubMed1998

Prevention of cerebral vasospasm by vasodilatory peptide maxadilan following subarachnoid hemorrhage in rabbits.

Maxadilan is a vasodilatory peptide isolated from the blood-feeding sand fly Lutzomyia longipalpis. Its vasodilatory activity, estimated by the formation of erythema on rabbit skin, is greater than those of calcitonin gene-related peptide, vasoactive intestinal polypeptide and pituitary adenylyl cyclase activating polypeptide (PACAP). We have recently demonstrated that maxadilan is a specific agonist for the PACAP type I receptor, which is widely distributed in brain. Therefore, we were interested in the vasodilatory effect of maxadilan on cerebral arteries and the possibility of its clinical use for the delayed cerebral vasospasm following subarachnoid (SAH). In the first experiment, 10(-10) mol/kg of maxadilan (in sterile water) was injected into the cisterna magna three days after the induction of experimental SAH in rabbits (n = 6). Maxadilan dilated spastic basilar arteries within 30 min of the injection, but not at 6 h. In the second experiment, to prolong the vasodilatory effect of maxadilan, tablets containing stearic acid, hydrogenated oil, lactose, hydroxypropylcellulose and 15 mg of maxadilan were prepared. In vitro testing showed that 60% of maxadilan could be released slowly within the initial five days. In vivo experiments were performed to implant the maxadilan tablet (n = 7) and the placebo tablet (n = 6) into the cisterna magna after the induction of experimental SAH in rabbits. The spastic response of the basilar artery was maximum on day three in the placebo-treated groups. In contrast, we observed no significant change in the arterial diameter until day five in the rabbits treated with maxadilan tablet. These data suggest that maxadilan may have therapeutic potency in treating cerebral vasospasm.

Animals↗
PubMed1998

The neuro-immuno-cutaneous-endocrine network: relationship of mind and skin.

Skin does more than present one's "face" to the world; it plays a vital role in the maintenance of physical and mental health. As our most ancient interface, skin retains the ability to respond to both endogenous and exogenous stimuli, sensing and integrating environmental cues while transmitting intrinsic conditions to the outside world. As such, it has long been a target for the application of both medical and nonmedical therapies of healthy and diseased states. Our understanding of how the skin and topical therapies affect health is in its infancy. Conversely, we known little of how our internal systems affect our skin. By exploring an elaborate web of neuro-immuno-cutaneous-endocrine (NICE) phenomena, we seek to shed light on the generally acknowledged, but inadequately defined, relationship between mental and physical health. We use skin as our window, noting some of the biological mediators linking nervous, immune, cutaneous, and endocrine functions. It is likely that these mediators are important in homeostasis, and that they affect several dermatologic and psychiatric conditions.

Endocrine System↗
PubMed1997

Maxadilan, the vasodilator from sand flies, is a specific pituitary adenylate cyclase activating peptide type I receptor agonist.

Maxadilan is a potent vasodilator peptide isolated from salivary gland lysates of the sand fly Lutzomyia longipalpis, a vector of leishmaniasis. The peptide aids the fly in obtaining blood from the skin of its vertebrate hosts but the mammalian receptor through which this insect ligand acts was unknown. We demonstrate that maxadilan is an agonist of the type I receptor for pituitary adenylate cyclase activating peptide, a neuropeptide with vascular activity. This surprising observation is a unique example of convergent evolution from a functional standpoint as these two peptides do not share significant sequence homology.

Adenylyl Cyclases↗
PubMed1996

Structural characterization and location of disulphide linkages of a potent vasodilatory peptide, recombinant maxadilan, by a multiple mass spectrometric approach.

A multiple mass spectrometric strategy using fast-atom bombardment (FAB) and matrix-assisted laser desorption/ionization (MALDI) has been used to confirm the sequence and to locate the disulfide linkages of recombinant maxadilan (r-maxadilan) (average molecular mass 7422.5 Da), a potent vasodilatory peptide from Lutzomyia longipalpis. MALDI measurements of intact r-maxadilan, its reduced form and its pyridylethylated form (p-maxadilan) indicated the presence of four Cys residues without major post-translational modifications. FAB and FAB-tandem mass spectrometry measurements of chymotryptic digests of p-maxadilan were sufficient to map the primary structure of p-maxadilan, though the complementary use of MALDI was necessary for complete mapping using Asp-N digestion due to a strong suppression observed in FAB. Assignment of the Cys-5-Cys-9 linkage was achieved by comparison of FAB mass spectra before and after reduction of tryptic digests of r-maxadilan. Since the molecular weight of the peptide fragment containing the Cys-18-Cys 55 linkage is more than 4000, MALDI measurement was indispensable for assignment of this linkage. The results fully support the value of the multiple mass spectrometric strategy in the structural characterization of peptides and proteins.

Amino Acid Sequence↗
PubMed1996

Leishmaniasis.

Leishmaniasis is a protozoan disease whose diverse clinical manifestations are dependent both on the infecting species of Leishmania and on the immune response of the host. Transmission of the disease occurs through the bite of a sand fly infected with Leishmania parasites. Infection may be restricted to the skin in cutaneous leishmaniasis, limited to the mucous membranes in mucosal leishmaniasis, or spread throughout the reticuloendothelial system in visceral leishmaniasis or kala azar. Three rare clinical variants of cutaneous leishmaniasis include diffuse cutaneous leishmaniasis, leishmaniasis recidivans, and post-kala-azar dermal leishmaniasis.

Animals↗
PubMed1996

Receptors for the vasodilator maxadilan are expressed on selected neural crest and smooth muscle-derived cells.

Maxadilan is a potent vasodilator peptide isolated from salivary glands of the blood feeding sand fly Lutzomyia longipalpis. The peptide relaxes rabbit aortic rings in an endothelium independent manner while elevating levels of cAMP and has been found to bind to membrane homogenates from brain. These studies on tissues have now been expanded with an examination of binding and signaling of maxadilan to a number of established cell lines and primary cultures. The data reveal that maxadilan binds to and stimulates the accumulation of cAMP in the rat pheochromocytoma line PC12 and the human neuroblastoma line NBfl. Accumulation of cAMP occurred in a transformed mouse pancreatic smooth muscle line (MILE) and primary rabbit aorta smooth muscle cells. The peptide did not bind to or induce cAMP formation in the rat thoracic aorta line L6. Scatchard analysis of binding to the PC12 and NBfl lines indicates that maxadilan binds to a single class of high-affinity receptors. Similar pharmacologic actions and possible structural homologies between maxadilan and calcitonin gene-related peptide (CGRP) suggested the possibility that they shared receptors. However, competition studies and comparative second messenger analysis reveal that maxadilan does not interact with receptors for CGRP, amylin or adrenomedullin and suggest that this peptide may bind to a novel receptor whose endogenous ligand remains unknown.

Adrenomedullin↗
PubMed1996

Langerhans cells express inducible nitric oxide synthase and produce nitric oxide.

The importance of nitric oxide (NO) in mediating macrophage functions has been demonstrated, but production of this potent gas has not been examined in Langerhans cells (LC). Using murine LC purified from epidermal cell suspensions and the recently established LC-like cell line derived from newborn BALB/c epidermis (XS-52), it was shown with reverse transcriptase (RT)-PCR that inducible nitric oxide synthase (iNOS) message is present in these cells. Murine keratinocytes did not contain iNOS message. iNOS mRNA was increased in a concentration-dependent manner by lipopolysaccharide (LPS) in purified murine LC and XS-52 cells, and immunofluorescence using an antibody to iNOS revealed bright cytoplasmic staining in LPS-treated XS-52 cells. Anti-iNOS antibody brightly stained LC on human neonatal foreskin cryosections. An increase in NO production by LPS-treated XS-52 cells over 16 h, as measured by the determination of nitrite levels in culture supernatants using the Griess Reaction, was observed. Interferon-gamma (IFNgamma) did not affect NO production on its own. In the presence of LPS and IFNgamma, NO production was 3 times more than observed with LPS alone. NO production was inhibited by the NOS inhibitor L-NAME. Western blots with anti-iNOS antibody demonstrated an increase in iNOS expression in LPS-treated XS-52 cells that was suppressed by IL-10. NO produced in LC may affect LC functions such as microbicidal activity, antigen presentation, and cytotoxicity and may affect adjacent keratinocytes and melanocytes.

Animals↗
PubMed1996

Immunomodulatory properties of maxadilan, the vasodilator peptide from sand fly salivary gland extracts.

Sand flies are the arthropod vector of leishmaniasis and salivary gland extracts from these flies exacerbate leishmaniasis in vivo. The mechanism of exacerbation appears to be due to immunomodulatory effects of the saliva on host immune function but the active component is unknown. The following studies reveal that maxadilan, the vasodilatory peptide present in sand fly salivary gland extracts, has immunomodulatory properties. To examine the effect of maxadilan on T cell proliferation, the peptide was added to murine spleen cells stimulated with either concanavalin A or plate-bound anti-T cell receptor antibody. Inhibition of proliferation was noted in a dose-dependent manner for both sets of experiments (P < 0.05). To examine the effect of maxadilan on alloantigen presentation, the peptide was added to mixed lymphocyte and mixed epidermal cell lymphocyte reactions. Inhibition of proliferation was found in these culture systems. Maxadilan also inhibited the delayed-type hypersensitivity reaction in mice (P < 0.05). These observations suggest a role for maxadilan in the pathogenesis of leishmaniasis since the peptide may inhibit the immune response at the site of parasite inoculation, allowing the infection to proceed.

Adjuvants, Immunologic↗
PubMed1996

From bedside to the bench and back. Nitric oxide and the cutis.

When the discoverer of dynamite (trinitrotoluene [TNT]), Alfred Nobel, was prescribed nitroglycerin for angina in 1895, he was certainly taken aback. Almost a century later, organic nitrates and their gaseous metabolic end product, nitric oxide (NO), were implicated in a vast array of biologically diverse activities. About 10 years ago, a series of discoveries from different avenues of research converged on NO, thrusting it into the limelight as a neurotransmitter, vasodilator, toxin, and modulator of immune function and inflammation. Nitric oxide has thus managed to capture the interest of scientists from a number of fields and holds center stage attention. Interest in NO among dermatologists has been slow to appear, however, and the literature on NO with respect to the skin is sparse when compared with the steep escalation in the number of articles published generally on NO since 1987 (Figure 1).

Blood Vessels↗
PubMed1995

Maxadilan binds to membrane fractions of brain tissue.

Maxadilan is a potent vasodilator peptide isolated from salivary glands extracts of the hematophagous sand fly. Besides effects on the cutaneous vasculature, it has also been shown to relax rabbit aortic rings while elevating levels of cAMP. As a result of the effects on the skin and aorta, it was elected to undertake an examination of the tissue distribution of binding sites for maxadilan. In addition to specific binding in rabbit aorta and spleen, binding was detected in brain from various species including human, bovine, rabbit, rat and mouse with a kD of between 85 and 201 pM. Competitive displacement of [125I] maxadilan by a number of known vasoconstrictor peptides, vasodilator peptides and small molecule receptor ligands did not occur in the rabbit brain preparation. These results suggest the presence of specific binding sites in mammalian tissue for maxadilan whose endogenous ligand remains unknown.

Animals↗
PubMed1995

Specific induction of cAMP in Langerhans cells by calcitonin gene-related peptide: relevance to functional effects.

Epidermal Langerhans cells (LC) are associated anatomically with epidermal nerves, and a product of these nerves, calcitonin gene-related peptide (CGRP), inhibits the antigen-presenting capacity of LC and macrophages. As the CGRP receptor appears to be coupled to Gs alpha protein, which in turn activates adenylate cyclase, the ability of CGRP to induce cAMP in LC was examined and correlated with functional effects. LC were isolated from murine epidermal cells using antibodies on magnetic microspheres. Exposure to CGRP induced a significant increase in cAMP content, which could be inhibited by coculture with a truncated form of CGRP [CGRP-(8-37)] that is a specific competitive inhibitor of CGRP. Substance P and calcitonin failed to induce cAMP in LC. Although culture in CGRP reduced the ability of murine epidermal cells enriched for LC content to present pigeon cytochrome c to a responsive clone or to present antigen for elicitation of delayed-type hypersensitivity in immune mice, culture in forskolin had little or no effect on antigen presentation despite increased cAMP content of LC as much or more than that induced by CGRP. The effect of CGRP on antigen presentation in these systems could be blocked with CGRP-(8-37). CGRP inhibited the induction of B7-2 by lipopolysaccharide on peritoneal macrophages and a LC line, whereas calcitonin did not. CGRP induces specific accumulation of cAMP in LC and inhibits LC antigen-presenting function by a receptor-mediated event. However, the induction of cAMP by itself does not account for inhibition of antigen presentation. Suppression of the expression of B7-2 may be one mechanism by which CGRP inhibits antigen presentation.

Animals↗
PubMed1995

Vasorelaxant and second messenger effects of maxadilan.

Maxadilan is a potent vasodilator isolated from salivary gland extracts of the sand fly. Although cutaneous vasodilatation is probably the most important physiologic effect of maxadilan (i.e., assisting the sand fly in obtaining a blood meal), it also has effects on other vascular beds. In rabbit isolated aorta, recombinant maxadilan exhibited endothelium-independent relaxations with an IC50 of 24 nM for norepinephrine-induced (1 microM) contractions. Synthetic maxadilan had one-third the potency, with a corresponding IC50 of 74 nM for norepinephrine-induced (1 microM) contractions. Pretreatment with a number of receptor and channel blockers, including tetraethylammonium (1 mM), glyburide (1 microM), barium (0.5 mM), indomethacin (10 microM), propranolol (10 microM), cimetidine (10 microM) and nifedipine (10 microM) did not affect maxadilan-induced relaxations. After treatment with maxadilan, contractions recurred very slowly over approximately 40 min. At a concentration of 1 microM, maxadilan induced a 2- to 3-fold increase in cellular cyclic AMP levels. Maxadilan's activity was selective according to vessel type, with maximal activity in rabbit aorta and mesenteric artery and no activity in porcine and bovine coronary arteries. These studies suggest that maxadilan acts by raising the intracellular levels of cyclic AMP in the smooth muscle of selected blood vessels.

Animals↗