Beta-adrenergic receptors in hamster smooth muscle cells are transcriptionally regulated by glucocorticoids

Steroid hormones modulate adrenergic receptor responsiveness and receptor number. To investigate the regulation of the beta 2-adrenergic receptor gene by glucocorticoids we examined the effects of the synthetic glucocorticoid agonist triamcinolone acetonide on the expression of beta 2-adrenergic receptors in DDT1MF-2 hamster smooth muscle cells. Glucocorticoid treatment (1 X 10(-7) M) produced a 2.2 +/- 0.4-fold (n = 8) increase in beta 2-adrenergic receptor number (maximum) between 6 and 12 h) as determined by radioligand binding and a similar increase in catecholamine-stimulated adenylate cyclase activity. Steady-state levels of beta 2-adrenergic receptor mRNA, analyzed by Northern blot hybridization, were increased 2.4 +/- 0.4-fold (n = 6) within 1 h, while actin mRNA levels were unchanged throughout the experiment. These steroid-induced increases in beta 2-adrenergic receptor mRNA returned to control levels by 24 h and were followed by a much slower decline in beta 2-adrenergic receptor in plasma membranes. The rate of beta 2-adrenergic receptor gene transcription, assessed by nuclear run-off transcription assays, increased 3.1 +/- 0.1-fold (n = 2) in cells treated for 30 min with 1 X 10(-7) M triamcinolone acetonide. These studies indicate that glucocorticoids regulate the beta 2-adrenergic receptor-adenylate cyclase system by controlling the rate of transcription of the beta 2-adrenergic receptor gene and hence the responsiveness of the enzyme to catecholamine stimulation.

Regulation of the beta 2-adrenergic receptor and its mRNA in the rat ventral prostate by testosterone

To investigate the regulation of beta 2AR expression in rat ventral prostate the effects of castration and testosterone replacement on the beta 2AR were studied by ligand binding and Northern blot analysis. Orchidectomy depressed beta 2AR number by 50% within 4 days and testosterone administration to 4-day castrates produced a rapid and complete recovery of beta 2AR number within 24 h. In contrast to receptor number, beta 2AR mRNA levels did not change relative to total RNA following castration. However, during the testosterone replacement period beta 2AR mRNA levels rose transiently, reaching a maximum (3.5-fold) between 8 and 12 h, and this increase in mRNA preceded the recovery in beta 2AR number in the membrane. Regulation of beta 2AR gene expression by testosterone in the ventral prostate is thus complex and probably involves both transcriptional and post-transcriptional components.

The effect of coronary angioplasty on coronary flow reserve

To determine the effects of coronary angioplasty on coronary flow reserve (CFR), we studied 32 patients before and immediately after single-vessel coronary angioplasty and 31 patients evaluated late after angioplasty (7.5 +/- 1.2 months, mean +/- SEM). The geometry (percent area stenosis and minimal cross-sectional area) of each lesion was determined by quantitative coronary angiography (Brown/Dodge method) and the integrated optical density was measured by videodensitometry. CFR was measured with a No. 3F coronary Doppler catheter placed immediately proximal to the lesion and a maximally vasodilating dose of intracoronary papaverine. The translesional pressure gradient was obtained in all lesions before and immediately after angioplasty and in 18 of 31 vessels late after angioplasty. CFR immediately after angioplasty returned to normal levels (greater than 3.5 peak/resting velocity ratio) in 14 of 31 patients and was improved, although not normalized, in the remaining 17 patients. CFR immediately after dilation was not significantly correlated with any of the angiographic variables of arterial stenosis nor the resting pressure gradient. Moreover, the pressure gradient and absolute distal coronary pressure at peak hyperemia were not significantly different in vessels with normal and those with abnormal flow reserve immediately after dilation, suggesting that the residual stenosis did not significantly limit hyperemia. Late after angioplasty, however, a significant relationship emerged between CFR and all four indexes of residual arterial stenosis (percent area stenosis r = .70, p less than .01; minimum arterial cross-sectional area r = .70, p less than .01; integrated optical density r = .60, p less than .01; and translesional pressure gradient r = .77, p less than .01). Furthermore, in the absence of restenosis, CFR eventually normalized in all patients. These findings demonstrate that in one-half of patients there is a transient reduction in coronary flow reserve immediately after angioplasty. In the absence of restenosis, coronary flow reserve later normalizes. Consequently, measurements of coronary flow reserve immediately after angioplasty may not reflect the eventual success of the procedure in removing physiologic obstruction to coronary blood flow.

Expression of a human cDNA encoding the beta 2-adrenergic receptor in Chinese hamster fibroblasts (CHW): functionality and regulation of the expressed receptors

A human beta-adrenergic receptor cDNA was transfected and expressed in transformed Chinese hamster fibroblasts (CHW). The expressed receptor exhibited a typical beta 2-adrenergic selectivity for agonists and antagonists as assessed by radioligand binding and adenylate cyclase activation. Guanine nucleotide-sensitive high affinity binding of the agonist, isoproterenol, indicated effective coupling of the expressed receptor to a guanine nucleotide-regulatory protein. The level of expression of beta 2-AR in various cell clones varied over 200-fold and was positively correlated with the levels of beta 2-AR mRNA. In cells expressing between 0.04 and 3.0 pmol of beta 2-AR/mg of membrane protein, the efficacy of isoproterenol for stimulating adenylate cyclase increased with increasing numbers of expressed receptors but reached a plateau and started to decrease in clones with higher beta 2-AR density (3.0-8.0 pmol/mg of membrane protein). Preincubation of beta 2-AR-expressing cells with isoproterenol for 15 min led to significant reduction in the level of isoproterenol-sensitive adenylate cyclase activity. This agonist-induced desensitization was also accompanied by phosphorylation of the beta 2-AR. These data indicate that the expressed human beta 2-AR displays typical functional characteristics of adenylate cyclase-coupled receptors including agonist-induced desensitization. Moreover, the availability of this series of cellular clones, which differ markedly in their density of beta 2-AR, provides a unique set of biological reagents for future studies of beta 2-AR function and regulation.

Cloning of the cDNA for the human beta 1-adrenergic receptor

Screening of a human placenta lambda gt11 library has led to the isolation of the cDNA for the human beta 1-adrenergic receptor (beta 1AR). Used as the probe was the human genomic clone termed G-21. This clone, which contains an intronless gene for a putative receptor, was previously isolated by virtue of its cross hybridization with the human beta 2-adrenergic receptor (beta 2AR). The 2.4-kilobase cDNA for the human beta 1AR encodes a protein of 477 amino acid residues that is 69% homologous with the avian beta AR but only 54% homologous with the human beta 2AR. This suggests that the avian gene encoding beta AR and the human gene encoding beta 1AR evolved from a common ancestral gene. RNA blot analysis indicates a message of 2.5 kilobases in rat tissues, with a pattern of tissue distribution consistent with beta 1AR binding. This pattern is quite distinct from the pattern obtained when the beta 2AR cDNA is used as a probe. Expression of receptor protein in Xenopus laevis oocytes conveys adenylate cyclase responsiveness to catecholamines with a typical beta 1AR specificity. This contrasts with the typical beta 2 subtype specificity observed when the human beta 2AR cDNA is expressed in this system. Mammalian beta 1AR and beta 2AR are thus products of distinct genes, both of which are apparently related to the putative G-21 receptor.

Intramedullary spinal cord metastasis in Hodgkin's disease. Rapid diagnosis and treatment resulting in neurologic recovery

Intramedullary spinal cord metastases are uncommon in Hodgkin's disease and have a poor prognosis. This prognosis reflects the refractory or widely disseminated status of the disease at the time of development of neurological symptoms and difficulties in diagnosis. Computerized tomography and magnetic resonance imaging have enabled more rapid and specific diagnosis of spinal cord diseases. The authors report a patient who presented with Brown-Sequard syndrome due to intramedullary spinal cord infiltration from Hodgkin's disease. This patient was diagnosed promptly and with rapid initiation of radiation and chemotherapy, she has had neurologic recovery.

An intronless gene encoding a potential member of the family of receptors coupled to guanine nucleotide regulatory proteins

Plasma membrane receptors for hormones, drugs, neurotransmitters and sensory stimuli are coupled to guanine nucleotide regulatory proteins. Recent cloning of the genes and/or cDNAs for several of these receptors including the visual pigment rhodopsin, the adenylate-cyclase stimulatory beta-adrenergic receptor and two subtypes of muscarinic cholinergic receptors has suggested that these are homologous proteins with several conserved structural and functional features. Whereas the rhodopsin gene consists of five exons interrupted by four introns, surprisingly the human and hamster beta-adrenergic receptor genes contain no introns in either their coding or untranslated sequences. We have cloned and sequenced a DNA fragment in the human genome which cross-hybridizes with a full-length beta 2-adrenergic receptor probe at reduced stringency. Like the beta 2-adrenergic receptor this gene appears to be intronless, containing an uninterrupted long open reading frame which encodes a putative protein with all the expected structural features of a G-protein-coupled receptor.

Expression of bcr and bcr-abl fusion transcripts in normal and leukemic cells

The translocation of the c-abl oncogene from chromosome 9 to the bcr gene on chromosome 22 in cases of Philadelphia chromosome-positive chronic myelogenous leukemia (CML) generates an aberrant bcr-abl fusion transcript which may be intimately related to the pathogenesis of CML. Because factors controlling normal bcr expression might also be involved in the expression of this aberrant bcr-abl transcript, we studied the patterns of expression of the normal bcr gene in different cell types. We found that the normal bcr gene was expressed in many different types of human cells. Moreover, the bcr gene was evolutionarily conserved, and homologous bcr genomic sequences and RNA transcripts were readily detected in chick tissue. The highest level of bcr expression in chick tissue was in brain tissue, the lowest level was in liver tissue, and a truncated bcr mRNA was noted in chick testes. Normal bcr transcripts, in addition to the aberrant bcr-abl hybrid transcripts, have been found in all Philadelphia chromosome-positive CML cells studied to date. Within a given CML sample, the relative amounts of normal bcr RNA and aberrant bcr-abl RNA were similar. In addition, the normal bcr and the aberrant bcr-abl hybrid transcripts demonstrated similarly prolonged half-lives compared with that of the normal abl-related transcripts in CML cells. These findings suggest that in CML cells, similar cellular mechanisms control the steady-state levels of both the normal bcr and the bcr-abl fusion RNAs.

Constitutive and inducible secretion of platelet-derived growth factor analogs by human leukemic cell lines coexpressing erythroid and megakaryocytic markers

We have examined the constitutive and inducible secretion of platelet-derived growth factor (PDGF)-like proteins in a variety of human hemopoietic cell lines. The highest levels of secreted protein were noted in four human erythroleukemia lines which, in addition to erythroid lineage markers, express one or more megakaryocytic lineage markers. Induction of these lines by 12-O-tetradecanoylphorbol-13-acetate enhanced the expression of megakaryocytic markers and increased secretion of PDGF-like proteins several fold. In concert with these changes, there was significant induction of c-sis/PDGF-B messenger RNA (mRNA) expression in all lines, whereas one line showed significant concurrent induction of PDGF-A mRNA expression. Whether PDGF-like secretion is part of the stem cell-like phenotype displayed by these lines or is secondary to their leukemic transformation remains to be determined. Nevertheless, these lines provide new cellular models for studying the expression and function of PDGF analogs in hemopoietic cells.

Purification of a benzo[a]pyrene binding protein by affinity chromatography and photoaffinity labeling

Binding proteins for the polycyclic aromatic hydrocarbon carcinogen benzo[a]pyrene (B[a]P) have been purified from C57B1/6J mouse liver. Following affinity chromatography on aminopyrene-Sepharose, a single polypeptide of 29,000 daltons was isolated. The photolabile compound 1-azidopyrene was developed as a photoaffinity labeling agent to identify the protein during its purification. 1-Azidopyrene was found to be a competitive inhibitor of [3H]B[a]P binding. Affinity labeling studies with [3H]-1-azidopyrene in unfractionated cytosol, and in purified preparations, yielded a single covalently labeled protein of 29,000 daltons. The formation of this labeled species was blocked by preincubation with excess unlabeled B[a]P. A native molecular weight of 30,000 was estimated by gel filtration chromatography of [3H]B[a]P- and [3H]-1-azidopyrene-labeled cytosol proteins. An equilibrium dissociation constant of 2.69 +/- 0.66 nM and a maximum number of binding sites of 2.07 +/- 0.10 nmol of [3H]B[a]P bound/mg of protein were estimated for the pure protein. Two-dimensional gel electrophoresis further resolved the purified 29,000-dalton protein into three major isoelectric variants, each of which was specifically labeled by [3H]-1-azidopyrene.

Plasmapheresis: an adjunct to medical management of severe hyperthyroidism

A woman with hyperthyroidism and myasthenia gravis developed respiratory failure in association with radiation-induced thyroiditis. Treatment with steroids, propylthiouracil, propranolol, iodine, and plasmapheresis was associated with dramatic reduction in serum triiodothyronine (T3), serum thyroxine (T4), and thyroglobulin levels and prompt recovery of the patient. The medications that this patient received have been shown to cause an abrupt decline in serum T3 levels with little or no effect on the serum T4 concentration. The 56% decline in serum T4 observed in this patient during the first 24 hours of therapy suggests that plasmapheresis may be a useful adjunct to medical therapy in selected patients with severe hyperthyroidism.

Use of the pill electrode for transesophageal atrial pacing

The pill electrode, which was developed for esophageal electrocardiography, has found application in transesophageal atrial pacing during procedures such as conversion of tachycardia, electrophysiologic measurement, and acceleration of heart rate to produce stress during cardiac imaging studies. This paper presents theoretical studies that examine the relationship of interelectrode distance, current level, and pulse duration to the achievement of successful capture. Theoretical results agree with our clinical findings, i.e., current levels of 25 mA are effective to sustain capture; increased pulse duration reduces current requirements; and close bipolar spacing combines efficacy with safety. Results of animal studies performed to assess the extent of esophageal burn injury reveal that current levels in excess of 75 mA are required to produce lesions in short-term (under 30 minutes) pacing, and greater than 60 mA in long-term (4 hours) pacing. These results are based on experiments using a pulse duration of 2 ms, and the current levels that produce injury will be considerably lower if longer pulse durations are used. Typical current levels and pulse durations for successful capture are presented for 46 subjects in several new clinical applications. Termination of tachycardia, basic electrophysiologic measurements, and controlled acceleration of heart rate can be performed noninvasively with this technique.

Development of an affinity chromatography resin for the purification of carcinogen binding proteins from mouse liver

Pyrene, a structural analog of benzo[a]pyrene, is an effective competing ligand for high affinity carcinogen binding proteins in mouse liver. A pyrene-derivatized Sepharose gel was prepared for affinity chromatography purification of these proteins, and adsorbs all detectable [3H]B[a]P-binding activity from hepatic cytosol with the adsorption of less than 1% of total protein. Specific carcinogen binding activity is recovered from pyrene-derivatized Sepharose columns with the enrichment of a 33 kDa polypeptide. This chromatography resin represents a major step in the isolation of these unusual receptor-like binding proteins for aromatic hydrocarbon carcinogens.

Human thoracic anatomy based on computed tomography for development of a totally implantable left ventricular assist system

Human thoracic anatomy was studied using computed tomography (CT) for the development of a totally implantable electrohydraulic left ventricular system [Nimbus, Inc., and The Cleveland Clinic Foundation (CCF)]. To obtain statistical dimensional information for the chest wall, apex of the heart, and aorta, routine calibrated CT scans of 18 men and 17 women were analyzed. A special radiopaque vest was worn by the patient just prior to the scanning and X-ray procedures, so that each transverse scan could be assigned to a specific chest level after combination with a standard vertical referencing system set on the patient's radiogram. A polar coordinate system and direct measurement of transverse distances from the vertical column to points on the chest wall were employed to define collectively the shape and size of the intrathoracic surface of the chest wall. Locations of the aorta and apex were described by measuring their normalized distances from the midline and vertical column to the intrathoracic surface of the lateral and anterior chest wall. The radius of curvature of the intrathoracic wall lateral to the left ventricle was determined to be approximately 10.4 cm for the average adult male chest. The present CCF intrathoracic pump with this curvature fits fairly well in both the average and individual thoraxes of these adult males. The location of the aorta, particularly of the descending aorta, was used to determine the optimal outlet design. The most critical anatomical area was the apex location. For adult males, an average distance of 2.8 cm from the apex to the internal chest wall was found. Because of this small dimension, careful design of the inflow port is being performed to avoid anatomical mismatch.

Carcinogen-binding proteins. High-affinity binding sites for benzo[a]pyrene in mouse liver distinct from the Ah receptor

Mouse liver cytosol contains saturable, high-affinity binding sites for the aromatic carcinogen benzo[a]pyrene that are distinct from the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-binding aryl hydrocarbon receptor. Specific binding parameters determined by an equilibrium binding assay indicate a dissociation constant of 7.7 nM and a binding capacity of 4.7 pmol of benzo[a]pyrene per milligram of cytosolic protein. Although the data best fit a single class of binding sites by Scatchard and Hill analyses, discrete 4 S and 9 S [3H]benzo[a]pyrene peaks are identified on sucrose density gradients comprising about 98% and 2% of the specific binding, respectively. Steroid hormones and other ligands for previously described binding proteins have no effect on the specific carcinogen binding when present in the cytosol incubation at saturating levels. The glutathione S-transferases, shown in rat and human liver to possess carcinogen-binding properties, were also found not to be responsible for this receptor-like benzo[a]pyrene binding in mouse liver cytosol. Competition binding studies indicate that other aromatic hydrocarbon compounds of a structure similar to that of benzo[a]pyrene are equipotent in affinity for this major carcinogen-binding site.

The effects of proglumide on cholecystokinin-, bombesin-, and glucagon-induced satiety in the rat

Intraperitoneal (IP) administration of the glutaramic acid derivative proglumide inhibited satiety induced by all IP doses of cholecystokinin octapeptide (CCK-OP) in 3-hour food-deprived intact rats. Proglumide did not influence satiety when administered alone and did not inhibit satiety induced by IP glucagon. While proglumide did not inhibit satiety induced by low doses of IP bombesin, it partially and significantly inhibited the satiety effects produced by high doses of this peptide. Since bombesin is a known secretagogue for CCK in several species, these results indicate that while bombesin and CCK act independently to induce satiety, the effect induced by high doses of bombesin is mediated, in part, by the release of endogenous CCK or a structurally related peptide. Furthermore, these results illustrate that proglumide is a specific antagonist of CCK-induced satiety and is, therefore, a potentially useful tool for investigating the physiologic role of this peptide in the control of food intake.

The treatment of obsessive-compulsive disorder in adolescence. A report of fifteen cases

The treatment of 15 adolescents with obsessive-compulsive disorder is described. Treatment was in most cases primarily behavioural (response-prevention), with the family involved in the therapy. Other components of treatment which were used in some cases are also described: medication, psychotherapy, and 'milieu' therapy. Outcome after treatment was generally good, with symptoms in most cases being relieved entirely or reduced to a mildly incapacitating level. Treatment gains in most cases were maintained at follow-up. Obstacles to treatment are noted, and recommendations are made as to the management of the disorder in adolescence.