Showing papers by "Jon Lindstrom published in 2004"

Acetylcholine Is an Autocrine or Paracrine Hormone Synthesized and Secreted by Airway Bronchial Epithelial Cells

Abstract: The role of acetylcholine (ACh) as a key neurotransmitter in the central and peripheral nervous system is well established However, the role of ACh may be broader because ACh may also function as an autocrine or paracrine signaling molecule in a variety of nonneuronal tissues To begin to establish ACh of nonneuronal origin as a paracrine hormone in lung, we have examined neonatal and adult monkey bronchial epithelium for the components involved in nicotinic cholinergic signaling Using immunohistochemistry and RT-PCR, we have demonstrated in lung bronchial epithelial cells (BECs) expression of choline acetyltransferase, the vesicular ACh transporter, the choline high-affinity transporter, alpha7, alpha4, and beta2 nicotinic ACh receptor (nAChR) subunits, and the nAChR accessory protein lynx1 Confocal microscopy demonstrates that these factors are expressed in epithelial cells and are clearly distinct from neighboring nerve fibers Confirmation of RNA identity has been confirmed by partial sequence analysis of PCR products and by cDNA cloning Primary culture of BECs confirms the synthesis and secretion of ACh and the activity of cholinesterases Thus, ACh meets all the criteria for an autocrine/paracrine hormone in lung bronchial epithelium The nonneuronal cholinergic signaling pathway in lung provides a potentially important target for cholinergic drugs This pathway may also explain some of the effects of nicotine on fetal development and also provides additional mechanisms by which smoking affects lung cancer growth and development

Analogs of α-conotoxin MII are selective for α6-containing nicotinic acetylcholine receptors

Abstract: Neuronal nicotinic acetylcholine receptors (nAChRs) both mediate direct cholinergic synaptic transmission and modulate synaptic transmission by other neurotransmitters. Novel ligands are needed as probes to discriminate among structurally related nAChR subtypes. Alpha-conotoxin MII, a selective ligand that discriminates among a variety of nAChR subtypes, fails to discriminate well between some subtypes containing the closely related alpha3 and alpha6 subunits. Structure-function analysis of alpha-conotoxin MII was performed in an attempt to generate analogs with preference for alpha6-containing [alpha6(*) (asterisks indicate the possible presence of additional subunits)] nAChRs. Alanine substitution resulted in several analogs with decreased activity at alpha3(*) versus alpha6(*) nAChRs heterologously expressed in Xenopus laevis oocytes. From the initial analogs, a series of mutations with two alanine substitutions was synthesized. Substitution at His9 and Leu15 (MII[H9A;L15A]) resulted in a 29-fold lower IC(50) at alpha6beta4 versus alpha3beta4 nAChRs. The peptide had a 590-fold lower IC(50) for alpha6/alpha3beta2 versus alpha3beta2 and a 2020-fold lower IC(50) for alpha6/alpha3beta2beta3 versus alpha3beta2 nAChRs. MII[H9A;L15A] had little or no activity at alpha2beta2, alpha2beta4, alpha3beta4, alpha4beta2, alpha4beta4, and alpha7 nAChRs. Functional block by MII[H9A;L15A] of rat alpha6/alpha3beta2beta3 nAChRs (IC(50) = 2.4 nM) correlated well with the inhibition constant of MII[H9A;L15A] for [(125)I]alpha-conotoxin MII binding to putative alpha6beta2(*) nAChRs in mouse brain homogenates (K(i) = 3.3 nM). Thus, structure-function analysis of alpha-conotoxin MII enabled the creation of novel selective antagonists for discriminating among nAChRs containing alpha3 and alpha6 subunits.

Plasma insulin and cardiovascular mortality in non-diabetic European men and women: a meta-analysis of data from eleven prospective studies.

Abstract: Plasma insulin and cardiovascular mortality in non-diabetic European men and women : a meta-analysis of data from eleven prospective studies.

Up-Regulation of Brain Nicotinic Acetylcholine Receptors in the Rat during Long-Term Self-Administration of Nicotine: Disproportionate Increase of the α6 Subunit

Abstract: In male rats continually self-administering nicotine (approximately 1.5 mg free base/kg/day), we found a significant increase of nicotinic acetylcholine receptors (nAChRs) labeled by epibatidine (Epb) in 11 brain areas. A large increase of high-affinity Epb binding sites was apparent in the ventral tegmentum/substantia nigra, nucleus tractus solitarii, nucleus accumbens, thalamus/subthalamus, parietal cortex, hypothalamus, and amygdala. A smaller but significant up-regulation of high-affinity Epb sites was seen in the piriform cortex, hippocampus, caudate/putamen, and cerebellar cortex. The up-regulation of nAChRs, shown by immunoadsorption and Western blotting, involved alpha4, alpha6, and beta2 subunits. As a consequence of long-term self-administration of nicotine, the alpha6 immunoreactive (IR) binding of either labeled Epb or 125I-alpha-conotoxin MII increased to a much greater extent than did alpha4 or beta2 IR binding of Epb. In addition, the beta2 IR binding of Epb was consistently enhanced to a greater extent than was alpha4. These findings may reflect a larger surface membrane retention of alpha6-containing and, to some degree, beta2-containing nAChRs compared with alpha4-containing nAChRs during long-term self-administration of nicotine.

Common polymorphisms in the genes regulating the early insulin signalling pathway: effects on weight change and the conversion from impaired glucose tolerance to type 2 diabetes

Abstract: Aims/hypothesis Type 2 diabetes is a complex disorder with strong heritability. The aim of our study was to investigate whether common polymorphisms in the genes regulating the early insulin signalling pathway (insulin; A-23T, insulin-like growth factor 1 receptor [IGF-1R]; GAG1013GAA, plasma cell membrane glycoprotein 1 [PC-1]; K121Q, insulin receptor substrate [IRS-1]; G972R, insulin receptor substrate 2 [IRS-2]; G1057D and phosphatidylinositol 3-kinase p85α [PI3K]; M326I) affect the weight change and development of Type 2 diabetes in the Finnish Diabetes Prevention Study.

Association between a deletion/insertion polymorphism in the α2B-adrenergic receptor gene and insulin secretion and Type 2 diabetes. The Finnish Diabetes Prevention Study

Abstract: Impaired insulin secretion has a strong genetic component. In this study we investigated whether the 12Glu9 polymorphism in the gene encoding the α2B-adrenergic receptor (ADRA2B) is associated with insulin secretion and/or the incidence of Type 2 diabetes in individuals with impaired glucose tolerance. We investigated a total of 506 subjects with impaired glucose tolerance participating in the Finnish Diabetes Prevention Study (DPS). Participants were randomly assigned to an intervention group or a control group. Anthropometric measurements and an oral glucose tolerance test were performed at baseline and at annual follow-up. In a subgroup of patients (n=83), a frequently sampled intravenous glucose tolerance test (FSIGT) was performed at baseline. All patients had similar anthropometric measurements and insulin and glucose levels at baseline. Multiple logistic regression analysis revealed significant interaction (p=0.003) between study group and genotype across the entire study population. In the control group, subjects with the Glu9 allele had an increased risk of developing Type 2 diabetes compared with subjects with the Glu12/12 genotype (odds ratio [OR]=2.68, 95% CI 1.02–7.09, p=0.047 for Glu12/12, and OR=5.17, 95% CI 1.76–15.21, p=0.003 for Glu9/9). This increased risk was not observed in the intervention group, who showed significant weight loss during the trial. In the subgroup who underwent the FSIGT, subjects with the Glu9/9 genotype showed the lowest acute insulin response (p=0.005 for trend). The 12Glu9 polymorphism of ADRA2B is associated with impaired first-phase insulin secretion and may predict the development of Type 2 diabetes in subjects with impaired glucose tolerance who are not subjected to a lifestyle intervention.

Childhood myopia and parental smoking

Abstract: Aim: To examine the relation between exposure to passive parental smoke and myopia in Chinese children in Singapore. Methods: 1334 Chinese children from three schools in Singapore were recruited, all of whom were participants in the Singapore Cohort study Of the Risk factors for Myopia (SCORM). Information on whether the father or mother smoked, number of years smoked, and the number of cigarettes smoked per day during the child’s lifetime were derived. These data were correlated with contemporaneously obtained data available in SCORM. The children’s cycloplegic autorefraction, corneal curvature radius, and biometry measures were compared with reported parental smoking history. Results: There were 434 fathers (33.3%) and 23 mothers (1.7%) who smoked during their child’s lifetime. There were no significant trends observed between paternal smoking and refractive error or axial length. After controlling for age, sex, school, mother’s education, and mother’s myopia, children with mothers who had ever smoked during their lifetime had more “positive” refractions (adjusted mean −0.28 D v −1.38 D) compared with children whose mother did not smoke (p = 0.012). Conclusions: The study found no consistent evidence of association between parental smoking and refractive error. There was a suggestion that children whose mothers smoked cigarettes had more hyperopic refractions, but the absence of a relation with paternal smoking and the small number of mothers who smoked in this sample preclude definite conclusions about a link between passive smoking exposure and myopia.

Is “seronegative” MG explained by autoantibodies to MuSK?

Abstract: Jon Lindstrom1 poses the question “Is ‘seronegative' MG explained by autoantibodies to MuSK?” We agree that muscle-specific receptor tyrosine kinase (MuSK) antibodies are not found in all myasthenia gravis (MG) patients seronegative for acetylcholine receptor (AchR) antibodies, their pathogenicity is still unclear, and there are other immune factors in seronegative MG,2–4 but we believe that MuSK antibodies are important. The editorial states, “autoantibodies to MuSK were not found where they were expected.” This referred to a Taiwanese report in which only 1/26 individuals with seronegative MG had MuSK antibodies. But 7/17 were positive in an accompanying Japanese study,5 closer to the 70% reported initially,2 and similar to the 41% in a more inclusive UK study.4 The observations support our growing evidence that the prevalence of MuSK antibodies …

Common variants in beta2- and beta3-adrenergic receptor genes and uncoupling protein 1 as predictors of the risk for type 2 diabetes and body weight changes. The Finnish Diabetes Prevention Study.

Abstract: To the Editor: Both diabetes and obesity have a strong genetic component and their inheritance is polygenic (1, 2). b-adrenergic receptors (b-ARs) and uncoupling proteins (UCPs) have been studied as candidate genes for obesity because of their role in the stimulation of thermogenesis and lipolysis (3, 4). A Gln27Glu polymorphism of b2-AR gene alters the down-regulation of the receptor in vitro (5) and has been associated with body weight (6, 7), hypertriglyceridemia (8, 9), and susceptibility to type 2 diabetes mellitus (T2DM) (10). A Trp64Arg polymorphism of b3-AR has been associated with weight gain, clinical features of insulin resistance, and early development of type 2 diabetes mellitus (T2DM) (10–13). Furthermore, the Arg allele is associated with 10-fold-decreased agonist sensitivity (14). Coexistence of variants in the b3-AR and b2-AR genes has been associatedwithT2DMin one study (10). The UCP1 gene variant A( 3826)G has been associated with obesity and metabolic disorders both individually and in combination with b3-AR (15–17). In this study, we explored the associations of the polymorphisms in b2-AR, b3-AR, andUCP1 genes with the incidence of T2DM and the changes in body weight in 490 individuals with impaired glucose tolerance (IGT) participating in the Finnish Diabetes Prevention Study (DPS) (18, 19). Altogether, 522 overweight individuals with IGT were randomized into either a lifestyle intervention or a control group in five clinics. The study design and methods have been reported in detail elsewhere (19). DNA was available for 490 subjects (mean BMI 31.3 4.6 kg/m, age 55.3 7.1 years). The study protocol was approved by the Ethics Committee of the National Public Health Institute in Helsinki, Finland. All participants gave written informed consent. A medical history was taken and a physical examination was performed at the baseline and at each annual follow-up visit. In this study, measurements at the baseline and at the 3-year examination were used. The genotyping was performed by polymerase chain reactionrestriction fragment length polymorphismmethod. The data were analyzed using the SPSS/WIN program version 11.0 (SPSS, Chicago, IL). At p< 0.05, differences were considered significant. In DPS study population, the allelic frequencies of the variants in b2-AR, b3-AR, and UCP1 genes were 0.40, 0.08, and 0.22, respectively. At baseline and at 3-year follow-up, no significant association was observed between the three polymorphisms and anthropometric measurements, glucose and insulin levels, after correcting for multiple testing. As for the UCP1 gene, subjects with G( 3826)G genotype showed the highest weight during 3 years of follow-up (repeated measures ANOVA, p1⁄4 0.029) (Fig. 1). During the 3-year follow-up, 69 individuals of those whose DNA sample was available developed T2DM. The risk of T2DM did not differ among the three genotypes of the b2-AR gene (Table 1), although a trend for increased risk in wild-type subjects could be seen. Individuals possessing the Arg64 variant of the b3-AR gene tended to have a higher incidence of T2DM, especially in the intervention group (Table 1). To analyze the possible additive effect of these two genes (10), we grouped the individuals with Glu27 and Trp64Trp as a low-risk combination and those with other combinations as a high-risk combination. A suggestive additive effect was Clin Genet 2004: 66: 365–367 Copyright # Blackwell Munksgaard 2004 Printed inDenmark. All rights reserved CLINICALGENETICS doi: 10.1111/j.1399-0004.2004.00313.x

Differential modulation of β2 and β4 subunits of human neuronal nicotinic acetylcholine receptors by acidification

Abstract: We have shown previously that acidification increases the affinity of agonists to rat α3β4 nicotinic acetylcholine receptors (nAChR) and accelerates both the activation and decay kinetics of agonist-induced currents recorded from human embryonic kidney 293 cells stably expressing the receptor (Abdrakhmanova et al., 2002b). Here, we report on experiments examining the effect of rapid acidification on four different subtypes (α3β4α5, α4β2, α3β2, and α3β2α5) of human neuronal nAChRs stably expressed in tsA201 cells using a piezoelectric device for rapid (

Research report Expression of a4 and a7 nicotinic receptors in the brainstem of female rabbits after coitus

Abstract: Coital signaling in the female rabbit involves sequential events in the brainstem and hypothalamus, resulting in a massive release of hypothalamic gonadotropin-releasing hormone (GnRH) that peaks within 1–2 h after mating. The neural connections between coitus and GnRH release involves norepinephrine (NE) and acetylcholine (ACh) since administration of antagonists against NE (dibenamine or phentolamine) or ACh (atropine, a-bungarotoxin (a-BTX) or scopolamine) blocks or attenuates ovulating events. Moreover, hypothalamic NE release and brainstem tyrosine hydroxylase (TH, the rate-limiting enzyme for NE synthesis) expression in the noradrenergic areas increase prior to, or in concert with, the preovulatory GnRH surge. How ACh is involved in the control of ovulation in the rabbit is lesser known. In the present study, the number of brainstem neurons expressing TH, a4 and a7 subunits of the nicotinic ACh receptor (nAChR) before and after coitus was determined by immunocytochemistry. Compared to non-mated female rabbits, the number of a4, a7 and TH single-labeled neurons as well as a4/TH and a7/TH double-labeled neurons increased in the A1, A2 and A6 brainstem noradrenergic areas at 1 h, but not 2 h, after coitus. The results suggest that the participation of ACh in the control of coitus-induced ovulation may include activation of a4h2 and a7 nAChRs in neurons within or adjacent to the brainstem noradrenergic areas in female rabbits. D 2004 Elsevier B.V. All rights reserved. Theme: Neurotransmitters, modulators, transporters and receptors Topic: Acetylcholine receptors: nicotinic