PubMed Health⌕ Search

Biomedical subjects

D A Schwinn

Publications and source records attributed to D A Schwinn.

At least 19 recordsLinked to original sources
PubMed2006

Inflammatory gene polymorphisms and risk of postoperative myocardial infarction after cardiac surgery.

BACKGROUND: The inflammatory response triggered by cardiac surgery with cardiopulmonary bypass (CPB) is a primary mechanism in the pathogenesis of postoperative myocardial infarction (PMI), a multifactorial disorder with significant inter-patient variability poorly predicted by clinical and procedural factors. We tested the hypothesis that candidate gene polymorphisms in inflammatory pathways contribute to risk of PMI after cardiac surgery. METHODS AND RESULTS: We genotyped 48 polymorphisms from 23 candidate genes in a prospective cohort of 434 patients undergoing elective cardiac surgery with CPB. PMI was defined as creatine kinase-MB isoenzyme level > or = 10x upper limit of normal at 24 hours postoperatively. A 2-step analysis strategy was used: marker selection, followed by model building. To minimize false-positive associations, we adjusted for multiple testing by permutation analysis, Bonferroni correction, and controlling the false discovery rate; 52 patients (12%) experienced PMI. After adjusting for multiple comparisons and clinical risk factors, 3 polymorphisms were found to be independent predictors of PMI (adjusted P<0.05; false discovery rate <10%). These gene variants encode the proinflammatory cytokine interleukin 6 (IL6 -572G>C; odds ratio [OR], 2.47), and 2 adhesion molecules: intercellular adhesion molecule-1 (ICAM1 Lys469Glu; OR, 1.88), and E-selectin (SELE 98G>T; OR, 0.16). The inclusion of genotypic information from these polymorphisms improved prediction models for PMI based on traditional risk factors alone (C-statistic 0.764 versus 0.703). CONCLUSIONS: Functional genetic variants in cytokine and leukocyte-endothelial interaction pathways are independently associated with severity of myonecrosis after cardiac surgery. This may aid in preoperative identification of high-risk cardiac surgical patients and development of novel cardioprotective strategies.

Aged↗
PubMed2005

Genetic factors contribute to bleeding after cardiac surgery.

BACKGROUND: Postoperative bleeding remains a common, serious problem for cardiac surgery patients, with striking inter-patient variability poorly explained by clinical, procedural, and biological markers. OBJECTIVE: We tested the hypothesis that genetic polymorphisms of coagulation proteins and platelet glycoproteins are associated with bleeding after cardiac surgery. PATIENTS/METHODS: Seven hundred and eighty patients undergoing aortocoronary surgery with cardiopulmonary bypass were studied. Clinical covariates previously associated with bleeding were recorded and DNA isolated from preoperative blood. Matrix Assisted Laser Desorption/Ionization, Time-Of-Flight (MALDI-TOF) mass spectroscopy or polymerase chain reaction were used for genotype analysis. Multivariable linear regression modeling, including all genetic main effects and two-way gene-gene interactions, related clinical and genetic predictors to bleeding from the thorax and mediastinum. RESULTS: Nineteen candidate polymorphisms were assessed; seven [GPIaIIa-52C>T and 807C>T, GPIb alpha 524C>T, tissue factor-603A>G, prothrombin 20210G>A, tissue factor pathway inhibitor-399C>T, and angiotensin converting enzyme (ACE) deletion/insertion] demonstrate significant association with bleeding (P < 0.01). Adding genetic to clinical predictors results improves the model, doubling overall ability to predict bleeding (P < 0.01). CONCLUSIONS: We identified seven genetic polymorphisms associated with bleeding after cardiac surgery. Genetic factors appear primarily independent of, and explain at least as much variation in bleeding as clinical covariates; combining genetic and clinical factors double our ability to predict bleeding after cardiac surgery. Accounting for genotype may be necessary when stratifying risk of bleeding after cardiac surgery.

Aged↗
PubMed2005

Neuron specific alpha-adrenergic receptor expression in human cerebellum: implications for emerging cerebellar roles in neurologic disease.

Recent data suggest novel functional roles for cerebellar involvement in a number of neurologic diseases. Function of cerebellar neurons is known to be modulated by norepinephrine and adrenergic receptors. The distribution of adrenergic receptor subtypes has been described in experimental animals, but corroboration of such studies in the human cerebellum, necessary for drug treatment, is still lacking. In the present work we studied cell-specific localizations of alpha1 adrenergic receptor subtype mRNA (alpha 1a, alpha 1b, alpha 1d), and alpha2 adrenergic receptor subtype mRNA (alpha 2a, alpha 2b, alpha 2c) by in situ hybridization on cryostat sections of human cerebellum (cortical layers and dentate nucleus). We observed unique neuron-specific alpha1 adrenergic receptor and alpha2 adrenergic receptor subtype distribution in human cerebellum. The cerebellar cortex expresses mRNA encoding all six alpha adrenergic receptor subtypes, whereas dentate nucleus neurons express all subtype mRNAs, except alpha 2a adrenergic receptor mRNA. All Purkinje cells label strongly for alpha 2a and alpha 2b adrenergic receptor mRNA. Additionally, Purkinje cells of the anterior lobe vermis (lobules I to V) and uvula/tonsil (lobules IX/HIX) express alpha 1a and alpha 2c subtypes, and Purkinje cells in the ansiform lobule (lobule HVII) and uvula/tonsil express alpha 1b and alpha 2c adrenergic receptor subtypes. Basket cells show a strong signal for alpha 1a, moderate signal for alpha 2a and light label for alpha 2b adrenergic receptor mRNA. In stellate cells, besides a strong label of alpha 2a adrenergic receptor mRNA in all and moderate label of alpha 2b message in select stellate cells, the inner stellate cells are also moderately positive for alpha 1b adrenergic receptor mRNA. Granule and Golgi cells express high levels of alpha 2a and alpha 2b adrenergic receptor mRNAs. These data contribute new information regarding specific location of adrenergic receptor subtypes in human cerebellar neurons. We discuss our observations in terms of possible modulatory roles of adrenergic receptor subtypes in cerebellar neurons responding to sensory and autonomic input signals, and review species differences in cerebellar adrenergic receptor expression.

Aged↗
PubMed2000

Beta(2)-adrenergic and several other G protein-coupled receptors in human atrial membranes activate both G(s) and G(i).

Cardiac G protein-coupled receptors that couple to Galpha(s) and stimulate cAMP formation (eg, beta-adrenergic, histamine, serotonin, and glucagon receptors) play a key role in cardiac inotropy. Recent studies in rodent cardiac myocytes and transfected cells have revealed that one of these receptors, the beta(2)-adrenergic receptor (AR), also couples to the inhibitory G protein Galpha(i) (activation of which inhibits cAMP formation). If beta(2)ARs could be shown to couple to Galpha(i) in the human heart, it would have important ramifications, because levels of Galpha(i) increase with age and in failing human heart. Therefore, we investigated whether beta(2)ARs in the human heart activate Galpha(i). By photoaffinity labeling human atrial membranes with [(32)P]azidoanilido-GTP, followed by immunoprecipitation with antibodies specific for Galpha(i), we found that Galpha(i) is activated by stimulation of beta(2)ARs but not of beta(1)ARs. In addition, we found that other Galpha(s)-coupled receptors also couple to Galpha(i), including histamine, serotonin, and glucagon. When coupling of these receptors to Galpha(i) is disrupted by pertussis toxin, their ability to stimulate adenylyl cyclase is enhanced. These data provide the first evidence that beta(2)AR and many other Galpha(s)-coupled receptors in human atrium also couple to Galpha(i) and that abolishing the coupling of these receptors to Galpha(i) increases the receptor-mediated adenylyl cyclase activity.

Adenylate Cyclase Toxin↗
PubMed2000

Alpha 1-adrenergic receptor regulation: basic science and clinical implications.

Adrenergic receptors (ARs) are members of the G-protein-coupled receptor family, which includes alpha 1ARs, alpha 2ARs, beta 1ARs, beta 2ARs, beta 3ARs, adenosine, muscarinic, angiotensin, endothelin receptors, and many others that are responsible for a large variety of physiologic effects through G-protein coupling. This review focuses on alpha 1ARs and their regulation at both the mRNA and protein levels. Currently, three alpha 1AR subtypes have been characterized both pharmacologically and at the gene level: alpha 1aAR, alpha 1bAR, and alpha 1dAR. These are expressed in a species- and tissue-dependent manner. Mutagenesis approaches have been extremely valuable in the identification of key residues that govern alpha 1AR ligand binding and signaling. These studies reveal that alpha 1ARs have evolved an exquisitely sensitive regulation of their activity in which any disruption of the native structure has profound effects on subsequent function and effector coupling. Significant advances have also been made in the elucidation of signaling pathway components, resulting in the identification of novel pathways that can lead to pathologic conditions. Specific topics include mitogen-activated protein kinase, phosphatidylinositol 3-kinase, and G-protein-coupled receptor cross-talk pathways. Within this context, recent studies identifying underlying transcriptional mechanisms involved in the regulation of the alpha 1AR subtypes are also discussed. Finally, given the potentially important role of alpha 1ARs in the vasculature, as well as in the pathology of many diseases, such as myocardial hypertrophy and benign prostatic hyperplasia, the clinical relevance of alpha 1AR distribution, pharmacology, and therapeutic intervention is reviewed.

Cardiomyopathy, Hypertrophic↗
PubMed2000

Alpha2-adrenergic receptors in human dorsal root ganglia: predominance of alpha2b and alpha2c subtype mRNAs.

BACKGROUND: Nonselective alpha2-adrenergic receptor (alpha2AR) agonists (e.g., clonidine) mediate antinociception in part through alpha2ARs in spinal cord dorsal horn; however, use of these agents for analgesia in humans is limited by unwanted sedation and hypotension. The authors previously demonstrated alpha2a approximately alpha2b > > > alpha2c mRNA in human spinal cord dorsal horn cell bodies. However, because 20% of dorsal horn alpha2ARs derive from cell bodies that reside in the associated dorsal root ganglion (DRG), it is important to evaluate alpha2AR expression in this tissue as well. Therefore, the authors evaluated the hypothesis that alpha2b mRNA, alpha2c mRNA, or both are present in human DRG. METHODS: Molecular approaches were used to determine alpha2AR expression in 28 human DRGs because of low overall receptor mRNA expression and small sample size. After creation of synthetic competitor cDNA and establishment of amplification conditions with parallel efficiencies, competitive reverse transcription polymerase chain reaction was performed using RNA isolated from human DRG. RESULTS: Overall expression of alpha2AR mRNA in DRG is low but reproducible at all spinal levels. alpha2b and alpha2cAR subtype mRNAs predominate (alpha2b approximately alpha2c), accounting for more than 95% of the total alpha2AR mRNA in DRG at all human spinal nerve root levels. CONCLUSIONS: Predominance of alpha2b and alpha2cAR mRNA in human DRG is distinct from alpha2AR mRNA expression in cell bodies originating in human spinal cord dorsal horn, where alpha2a and alpha2b predominate with little or absent alpha2c expression. These findings also highlight species heterogeneity in alpha2AR expression in DRG. If confirmed at a protein level, these findings provide an additional step in unraveling mechanisms involved in complex neural pathways such as those for pain.

Adult↗
PubMed2000

Endogenous circulating sympatholytic factor in orthostatic intolerance.

Sympathotonic orthostatic hypotension (SOH) is an idiopathic syndrome characterized by tachycardia, hypotension, elevated plasma norepinephrine, and symptoms of orthostatic intolerance provoked by assumption of an upright posture. We studied a woman with severe progressive SOH with blood pressure unresponsive to the pressor effects of alpha(1)-adrenergic receptor (AR) agonists. We tested the hypothesis that a circulating factor in this patient interferes with vascular adrenergic neurotransmission. Preincubation of porcine pulmonary artery vessel rings with patient plasma produced a dose-dependent inhibition of vasoconstriction to phenylephrine in vitro, abolished vasoconstriction to direct electrical stimulation, and had no effect on nonadrenergic vasoconstrictive stimuli (endothelin-1), PGF-2alpha (or KCl). Preincubation of vessels with control plasma was devoid of these effects. SOH plasma inhibited the binding of an alpha(1)-selective antagonist radioligand ([(125)I]HEAT) to membrane fractions derived from porcine pulmonary artery vessel rings, rat liver, and cell lines selectively overexpressing human ARs of the alpha(1B) subtype but not other AR subtypes (alpha(1A) and alpha(1D)). We conclude that a factor in SOH plasma can selectively and irreversibly inhibit adrenergic ligand binding to alpha(1B) ARs. We propose that this factor contributes to a novel pathogenesis for SOH in this patient. This patient's syndrome represents a new disease entity, and her plasma may provide a unique tool for probing the selective functions of alpha(1)-ARs.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed2000

Immortalization of a human prostate stromal cell line using a recombinant retroviral approach.

PURPOSE: We established an immortalized human prostate stromal cell line with retained markers of cell differentiation and alpha1-adrenergic receptor expression. MATERIALS AND METHODS: Primary human prostate stromal explants were infected with an amphotrophic retrovirus encoding the E6/E7 open reading frame of the human papillomavirus type 16. Immunohistochemistry was used to verify the expression of prostate stromal markers. alpha1-Adrenergic receptor expression was investigated using ribonuclease protection assays and radioligand binding. Cell proliferation was measured by the WST-1 assay and cell counting. RESULTS: Clonal isolates of individual prostate stromal cells were isolated and passed in selection media. E6 and E7 expression was verified using reverse transcriptase polymerase chain reaction in the selected cell line. The new prostate stromal cell line PS30 was established which maintains the expression of alpha-smooth muscle actin and expresses 22 fmol./mg. of protein of alpha 1-adrenergic receptors, approximately equal to native human prostate alpha 1-adrenergic receptor expression. However, at a subtype level alpha 1a-adrenergic receptor expression is down-regulated and not detectable by ribonuclease protection assays or radioligand binding, while alpha 1b and alpha 1d-adrenergic receptor expression is enhanced. From a physiological prospective PS30 cells do not form tumors in nude mice and stimulation with phenylephrine does not increase cell proliferation. CONCLUSIONS: We successfully established and characterized an in vitro human prostate stromal cell line. This cell line should facilitate studies designed to characterize the role of the adrenergic nervous system in the regulation of prostate growth.

Actins↗
PubMed1999

Subtype specific regulation of human vascular alpha(1)-adrenergic receptors by vessel bed and age.

BACKGROUND: alpha(1)-adrenergic receptors (alpha(1)ARs) regulate blood pressure, regional vascular resistance, and venous capacitance; the exact subtype (alpha(1a), alpha(1b), alpha(1 d)) mediating these effects is unknown and varies with species studied. In order to understand mechanisms underlying cardiovascular responses to acute stress and chronic catecholamine exposure (as seen with aging), we tested two hypotheses: (1) human alpha(1)AR subtype expression differs with vascular bed, and (2) age influences human vascular alpha(1)AR subtype expression. METHODS AND RESULTS: Five hundred vessels from 384 patients were examined for alpha(1)AR subtype distribution at mRNA and protein levels (RNase protection assays, ligand binding, contraction assays). Overall vessel alpha(1)AR density is 16+/-2.3fmol/mg total protein. alpha(1a)AR predominates in arteries at mRNA (P<0.001) and protein (P<0.05) levels; all 3 subtypes are present in veins. Furthermore, alpha(1)AR mRNA subtype expression varies with vessel bed (alpha(1a) higher in splanchnic versus central arteries, P<0.05); competition analysis (selected vessels) and functional assays demonstrate alpha(1a) and alpha(1b)-mediated mammary artery contraction. Overall alpha(1)AR expression doubles with age (<55 versus > or = 65 years) in mammary artery (no change in saphenous vein), accompanied by increased alpha(1b)>alpha(1a) expression (P< = 0.001). CONCLUSIONS: Human vascular alpha(1)AR subtype distribution differs from animal models, varies with vessel bed, correlates with contraction in mammary artery, and is modulated by aging. These findings provide potential novel targets for therapeutic intervention in many clinical settings.

Adrenergic alpha-Agonists↗
PubMed1999

Alpha1-adrenergic receptors in human spinal cord: specific localized expression of mRNA encoding alpha1-adrenergic receptor subtypes at four distinct levels.

alpha1-Adrenergic receptors (alpha1ARs) are important in lower urinary tract syndromes such as benign prostatic hypertrophy and bladder irritability. Spinal cord alpha1ARs have been postulated to play a role in modulating these diseases, yet alpha1AR subtype (alpha1a, alpha1b, alpha1d) neuronal localization in human spinal cord has not been described. We therefore tested the hypothesis that alpha1AR subtype distribution varies according to specific spinal cord tract and level. In situ hybridization was performed to identify cell bodies containing alpha1AR subtype mRNA at four levels of human spinal cord (cervical enlargement, thoracic, lumbar, sacral). alpha1AR mRNA is present in ventral gray matter only (ventral>dorsal; sacral>lumbar=thoracic>cervical). Signaling cell bodies were detected in anterior horn motor neurons at all levels; dorsal nucleus of Clarke and intermediolateral columns in cervical enlargement, thoracic and lumbar spinal cord regions; and parasympathetic nucleus in sacral spinal cord. Although all three alpha1AR subtypes are present throughout human spinal cord, alpha1d mRNA predominates overall. If confirmed at a protein level, these findings may contribute to the development of new therapeutic strategies in the treatment of several human diseases.

Humans↗
PubMed1999

Molecular pharmacology of human alpha1-adrenergic receptors: unique features of the alpha 1a-subtype.

alpha1-Adrenergic receptors (alpha1ARs) are G protein-coupled receptors important in the dynamic component of benign prostatic hyperplasia. alpha1ARs stimulate predominantly phospholipase C-beta, resulting in mobilization of calcium from intracellular stores and, ultimately, smooth muscle contraction. cDNAs encoding three human alpha1ARs (alpha1a, alpha1b, alpha1d) have been cloned, expressed stably in cells, and characterized pharmacologically. Extensive species heterogeneity in tissue distribution emphasizes the importance of studying alpha1ARs in human tissues. Because of the important role of alpha1aARs in mediating prostate smooth muscle contraction, this current review describes alpha1a carboxyl terminal splice variants, examines alpha1AR subtype distribution in various tissues and the role of the putative alpha1LAR in human prostate, provides a brief discussion regarding regulation of this receptor by agonist, and finally discusses implications of distinct alpha1AR subtype distribution in human bladder compared with prostate.

Adrenergic alpha-Antagonists↗
PubMed1999

Activation of extracellular signal-regulated kinase in human prostate cancer.

PURPOSE: To investigate the level of expression, activation state, and functional significance of extracellular signal regulated kinase (ERK) in prostate cancer. MATERIALS AND METHODS: Human prostate tissue samples (n = 22) were obtained from patients undergoing radical prostatectomy for localized adenocarcinoma of the prostate (n = 16, age range 44 to 72 years) or normal prostate specimens (n = 6, age ranges 19 to 47 years) obtained from rapid autopsy. Immunoblots, in vitro kinase assays, and immunohistochemistry were used to determine the expression and activation state of ERK in human prostate cancer. RESULTS: Immunoblot and in vitro kinase assays demonstrated a 15-fold increase in ERK activation in prostate cancer specimens compared with normal human prostate tissue; however, ERK expression levels were only 1.3-fold higher in cancer. Immunohistochemical analysis demonstrated similar expression of ERK in cancer and normal tissues; however, phosphorylated ERK demonstrated greater intensity in the cancer specimens. Experiments conducted on a prostate cancer cell line demonstrated that EGF induced activation of ERK and cellular proliferation was partially inhibited by PD98059, a chemical inhibitor of the immediate upstream signaling component responsible of activation of ERK. CONCLUSIONS: Collectively, these data demonstrate a dramatic increase in ERK activation in prostate cancer compared with normal prostate tissue and suggest that inhibitors designed to target this signal transduction cascade might have therapeutic benefit in the treatment of prostate cancer.

Adenocarcinoma↗