Biomedical subjects

G Skoglund

Publications and source records attributed to G Skoglund.

At least 19 recordsLinked to original sources

PubMed2001

[Task and task time should dictate the choice of gloves in health care services].

Worldwide consumption of medical gloves increased during the 1980's due to the recognized risk of cross infections in medical and dental care. In Stockholm County Council around 1 million pairs of surgical gloves and 18 millions pairs of examination gloves are purchased per year. In the following paper different glove materials and types are presented and also regulations on use and purchase. The protective capacity of gloves and contact hypersensitivity reactions are also discussed and advice is provided on glove usage.

Dermatitis, Allergic Contact↗

PubMed2000

Glucagon-like peptide 1 stimulates insulin gene promoter activity by protein kinase A-independent activation of the rat insulin I gene cAMP response element.

Glucagon-like peptide 1 (GLP-1), a hormonal activator of adenyl cyclase, stimulates insulin gene transcription, an effect mediated by the cAMP response element (CRE) of the rat insulin I gene promoter (RIP1). Here we demonstrate that the signaling mechanism underlying stimulatory effects of GLP-1 on insulin gene transcription results from protein kinase A (PKA)-independent activation of the RIP1 CRE. Although GLP-1 stimulates cAMP production in rat INS-1 insulinoma cells, we find accompanying activation of a -410-bp RIP1 luciferase construct (-410RIP1-LUC) to exist independently of this second messenger. GLP-1 produced a dose-dependent stimulation of -410RIP1-LUC (EC50 0.43 nmol/l), an effect reproduced by the GLP-1 receptor agonist exendin-4 and abolished by the antagonist exendin(9-39). Activation of RIP1 by GLP-1 was not affected by cotransfection with dominant-negative Gs alpha, was not blocked by cAMP antagonist Rp-cAMPS, and was insensitive to PKA antagonist H-89. Truncation of -410RIP1-LUC to generate -307-, -206-, and -166-bp constructs revealed 2 segments of RIP1 targeted by GLP-1. The first segment, not regulated by forskolin, was located between -410 and -307 bp of the promoter. The second segment, regulated by both GLP-1 and forskolin, included the CRE and was located between -206 and -166 bp. Consistent with these observations, stimulatory effects of GLP-1 at RIP1 were reduced after introduction of delta-182 and delta-183/180 inactivating deletions at the CRE. The action of GLP-1 at -410RIP1-LUC was also reduced by cotransfection with A-CREB, a genetically engineered isoform of the CRE binding protein CREB, which dimerizes with and prevents binding of basic-region-leucine-zipper (bZIP) transcription factors to the CRE. In contrast, the action of GLP-1 at the CRE was not blocked by cotransfection with M1-CREB, an isoform that lacks a consensus serine residue serving as substrate for PKA-mediated phosphorylation. On the basis of these studies, it is proposed that PKA-independent stimulatory actions of GLP-1 at RIP1 are mediated by bZIP transcription factors related in structure but not identical to CREB.

Animals↗

PubMed1999

Cell-specific localization of G protein alpha-subunits in the islets of Langerhans.

G protein alpha-subunits are involved in the transduction of receptor-mediated regulation of insulin and glucagon secretions. To get further insight into the status of G proteins in alpha- and beta-cells of the Langerhans islets, we have used immunohistochemistry to study the distribution of alpha-subunits in pancreas sections from the rat. Our results show that only insulin-immunoreactive beta-cells display immunoreactivity for selective antibodies directed against the different members of the Galphas and Galpha12-families (alphas, alphaolf, and alpha12, alpha13 respectively). Immunoreactivities for antibodies directed against members of the Galphaq- and Galphai-families showed a more diverse localization: alpha11 and alphao2 were only detected in glucagon-immunoreactive alpha-cells, whereas alphai1 was detected in all beta-cells but only in a few alpha-cells. Even though beta-cells showed immunoreactivities for alphao-non-isoform-selective antibodies, we could not identify the isoform(s) present using selective alphao1 and alphao2 antibodies. Other members of the Galphai- and Galphaq-families (alphai3, alphat2, alphaz and alphaq) were detected in both alpha- and beta-cells. In conclusion, our findings demonstrate a clear difference in the localization of G protein alpha-subunits between alpha- and beta-cells, suggesting the involvement of specific receptor transduction pathways for the neuronal/hormonal regulation of alpha- and beta-cell functions.

Animals↗

PubMed1997

Cell surface and serum protein phosphorylation by U-937 cell ectoprotein kinases.

Incubation of intact U-937 cells with 0.1 microM [gamma-32P]ATP for 10 min resulted in Mg(2+)-independent radiolabelling of about 40 cell surface proteins, some of which became more intensely labelled when cells were differentiated. Presence of 2% newborn calf serum revealed major labelling of three serum proteins with molecular weights of 170, 85 and 61 kDa. Out of several tested purified human serum proteins, complement factor 1s (C1s) exhibited specific labelling of the 28 kDa subunit. This capacity of monocytic cell ectokinases to phosphorylate cell surface and serum proteins may have significance for the regulation of interactions between these cells and their environment. In addition, phosphorylation of components of the complement system suggest a possible new means of regulating the immune response through the action of extracellular kinases.

Blood Proteins↗

PubMed1996

Pancreatic beta-cell receptors and G proteins coupled to adenylyl cyclase.

Glucagon and tGLP-1 receptors can be either coexpressed or selectively expressed in beta-cell models. Our results indicate that both these peptides can regulate insulin secretion from beta-cells through their own specific receptors. The finding of a selective expression of G proteins in insulin and glucagon cells indicates a clear difference in their transduction pathways. A key role of the G alpha s family in beta-cell function is further supported by its conserved cell distribution between different species. In conclusion, one could postulate that in the human beta-cells, tGLP-1 and glucagon receptors could mediate their action through different G protein alpha-subunits of the G alpha s family.

Adenylyl Cyclases↗

PubMed1996

Glucagon acts through its own receptors in the presence of functional glucagon-like peptide-1 receptors on hamster insulinoma.

The observations that glucagon binds to glucagon-like peptide-1 (tGLP-1) receptors have raised the question of whether glucagon receptors mediate the insulinotropic effect of glucagon. We have investigated the presence and selective activation of glucagon and tGLP-1 receptors on tumor-derived cells. Northern blot analysis detected either glucagon or tGLP-1 receptor messenger RNA in hamster (HIT) and mouse (beta TC3) beta-cell lines, respectively, whereas both receptor messenger RNA were revealed in Syrian hamster insulinoma. Their expression in insulinoma plasma membranes was confirmed by specific covalent labeling with either [125I]glucagon or [125I]tGLP-1. Both glucagon and tGLP-1 receptors showed a single class of high affinity binding sites with respective Kd values of 1.11 +/- 0.11 and 0.82 +/- 0.11 nM. [125I]tGLP binding was dose dependently inhibited with a hierarchy of exendin-4 > tGLP-1 > exendin-(9-39) > oxyntomodulin > glucagon. [125I]Glucagon binding was only inhibited by glucagon and oxyntomodulin. Both glucagon and tGLP-1 increased cAMP formation in insulinoma plasma membranes in a dose-dependent manner, with ED50 values of 170.0 +/- 25.0 and 3.1 +/- 0.4 pM, respectively. Exendin-(9-39), a tGLP-1 receptor antagonist, inhibited tGLP-1-induced, but not glucagon-induced, cAMP formation. Our data demonstrate on hamster insulinoma the presence of high affinity glucagon and tGLP-1 receptors selectively coupled to adenylyl cyclase. The observed low affinity of tGLP-1 receptors for glucagon sustains the idea that each hormone has a direct insulinotropic effect.

Adenylyl Cyclase Inhibitors↗

PubMed1995

Protein kinase activities in Leishmania aethiopica: control by growth, transformation and inhibitors.

Promastigotes of L. aethiopica express an ectokinase activity preferring histone V-S as substrate. A soluble kinase activity utilizing protamine and histone V-S, as well as a particulate fraction associated kinase activity preferring protamine are also expressed. The soluble histone kinase activity, but not the ectokinase, was expressed at a higher level in cells from late phases of growth, as compared to early log phase cultures. Transformation of L. aethiopica to an amastigote-like stage, resulted in almost complete loss of the kinase activities, with retained viability of the cells. Formycin-ATP only weakly inhibited the kinases while effectively inhibiting cell growth and thymidine incorporation. Staurosporin efficiently blocked the kinase activities and cell growth without affecting thymidine incorporation.

Alkaloids↗

PubMed1995

Ectoprotein kinase activities on non-differentiated and differentiated U-937 cells.

Incubation of intact U-937 cells with 1 micron [gamma-32P] ATP resulted in rapid (10 min) incorporation of radioactivity into phosvitin, kemptide and protein kinase C (PKC)-peptide. The amount of incorporation was dependent on substrate type and concentration, and on incubation time. Staurosporine, H-7 and Mg(2+)-exclusion abolished phosphorylation of kemptide and PKC-peptide but not phosvitin. Cyclic AMP and phorbol ester enhanced kemptide and PKC-peptide phosphorylation. Protein kinase inhibitor (PKI) inhibits only kemptide phosphorylation. Cell differentiation enhanced 2-fold the phosphorylation of phosvitin and PKC-peptide without significant effect on kemptide phosphorylation. ATP concentrations sufficient to trigger changes in intracellular Ca2+ were sufficient to support extracellular phosphorylation reactions. The results suggest the presence of at least three ectokinase activities on U-937 cells that may play important roles in regulating membrane associated specific functions of developing and mature monocytes.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1994

Calcitonin gene-related peptide and islet amyloid polypeptide stimulate insulin secretion in RINm5F cells through a common receptor coupled to a generation of cAMP.

The question as to whether the homologous peptides CGRP and IAPP can regulate insulin secretion in RINm5F cells was addressed. Chicken CGRP displayed a reproducible inhibitory effect on insulin secretion within 0.1 and 1 nM concentrations and a stimulatory effect at higher concentrations. The maximal stimulatory effects on insulin secretion were obtained with 1.0 microM of chicken CGRP (cCGRP), human alpha-CGRP (h alpha-CGRP) and human IAPP (hIAPP) which caused 246 +/- 22, 302 +/- 63 and 224 +/- 14 percent increases of control levels, respectively (p < 0.001). Similarly, maximal accumulations of cAMP were obtained with 1.0 microM of cCGRP, h alpha-CGRP and hIAPP with the respective percent increases of control levels of 587 +/- 24, 436 +/- 41 and 410 +/- 25 (p < 0.005). Thus the stimulatory effects on insulin secretion in RINm5F cells by cCGRP, h alpha-CGRP and hIAPP appear to be mediated by the cAMP pathway. Chicken CGRP, the most potent peptide tested, displayed a correlated dose response stimulation of intracellular cAMP and insulin release within the concentration range of 10-1000nM. The EC50 values of cCGRP for cAMP accumulation and insulin release were similar (20nM and 10nM respectively). The stimulatory effect of IAPP on cAMP was not additive with that of cCGRP suggesting that IAPP action was mediated by CGRP receptors. This hypothesis was further sustained by a preferential inhibition of 125I[His]h alpha-CGRP binding to RINm5F cells by cCGRP as compared to IAPP. We conclude that CGRP and IAPP, through a direct action on a chicken CGRP preferring receptor present in beta cells, stimulated insulin by a cAMP mediated pathway.

Amyloid↗

PubMed1993

Different mechanisms are involved in neuropeptide Y-induced pancreatic vasoconstriction and inhibition of insulin secretion.

We have studied the mechanisms whereby neuropeptide Y (NPY) inhibits insulin secretion and induces vasoconstriction in the isolated perfused rat pancreas. Neither prazosin (alpha 1-adrenoceptor antagonist; 6 microM) nor yohimbine (alpha 2-adrenoceptor antagonist; 0.6 microM) affected the effects of neuropeptide Y (1 nM). Also the Ca2+ channel antagonist, verapamil (5 microM), which itself decreased insulin output by 55%, could not affect the neuropeptide Y-induced inhibition of insulin secretion. However, verapamil impaired the neuropeptide Y-induced decrease in pancreatic outflow rate. Finally, neuropeptide Y (1 and 10 nM) suppressed the insulin secretion induced by dibutyryl cAMP (100 microM) and the cyclic nucleotide suppressed the neuropeptide Y-induced vasoconstriction. We conclude that the secretory and vascular effects of neuropeptide Y are mediated by different processes in the perfused rat pancreas: inhibition of insulin secretion seems mediated by a mechanism distal to and/or different from cAMP generation, whereas vasoconstriction seems to involve uptake of extracellular Ca2+ and to be sensitive to dibutyryl cAMP. Both effects occur independently of adrenoceptor receptors.

Adrenergic alpha-Antagonists↗

PubMed1993

Differential regulation of gelatinase B and tissue-type plasminogen activator expression in human Bowes melanoma cells.

A comparison of the production of tissue-type plasminogen activator (t-PA) and gelatinases A and B was made at the mRNA and protein levels in human Bowes melanoma cells treated with phorbol myristate acetate (PMA). Immunocytochemical analysis confirmed previous quantitative data on PMA-mediated induction of t-PA. It also showed that t-PA immunoreactivity can be restrained to the local environment of the producing cell, most probably by interaction with extracellular matrix components. Zymographical analysis showed that gelatinase B protein was induced by PMA, whereas gelatinase A remained at the constitutive level. Protein kinase C (PKC) appeared to be involved in this regulation since, after PMA treatment (1) the PKC activity was found to be translocated from the cytosol to the particulate fraction of the cells and (2) addition of staurosporine and H-7 blocked the gelatinase B increase. Northern-blot hybridization showed a transient rise in t-PA and gelatinase B mRNA levels whereas gelatinase A mRNA levels remained unchanged. When c-fos and c-jun mRNAs were investigated, only that of c-fos was affected by PMA. Activation by PMA can be kinetically ordered as follows: translocation of PKC to the membrane fraction, transcription of the c-fos gene and eclipsing of gelatinase B mRNA, increase in steady-state mRNA levels of t-PA and gelatinase B and, finally, secretion of t-PA and gelatinase B glycoproteins. Our data also suggest that various proteases that are known to cooperate in the remodeling of the extracellular matrix can be differently regulated in one tumor-cell type.

Cell Compartmentation↗

PubMed1993

Evidence for an influence of the peri-arterial hepatic nerves on basal insulin-secretion in the rat.

We studied the in vivo sensitivity of isolated pancreatic islets to glucose and glucagon 1 week after in vivo micro-surgical denervation of the peri-arterial hepatic nerves in the rat. Basal insulin secretion (at 3.3 mM glucose) was significantly higher in denervated than in sham operated or control animals (137 +/- 27 microU/ml vs. 35 +/- 2 microU/ml, P = 0.004 and 58 +/- 15 microU/ml, P = 0.041, respectively). Also after stimulation with 13.3 mM glucose, insulin secretion was significantly higher in denervated cf. to sham operated animals (388 +/- 50 microU/ml vs. 211 +/- 6 microU/ml, P = 0.005), but not significantly vs. controls (273 +/- 41 microU/ml). In contrast, when the islets were stimulated with glucagon (10(-9)-10(-5) M) at basal glucose concentrations (3.3 mM), the increment of insulin secretion was not significantly higher in the denervated animals vs. control animals. Our findings indicate the existence of a neural control mechanism of basal insulin secretion from the pancreatic islets mediated through the peri-arterial autonomic hepatic nerves.

Animals↗

PubMed1993

Selective inhibition by H7 and staurosporin of phorbol ester responses in U-937 cells.

The kinase inhibitors H7 and staurosporin dose-dependently stimulate adhesion U-937 cells to plastic but fail to inhibit the CD11b/CD18-dependent adhesion of U-937 cells induced by phorbol ester. The protein kinase C activity of U-937 cells, measured as phorbol ester-stimulated phosphorylation of pep epsilon in streptolysin-O permeabilized cells, is strongly inhibited by the kinase inhibitors. H7 and staurosporin efficiently overcome the inhibitory effect of phorbol-12,13-dibutyrate (PDBu) on leukotriene D4-induced increase in intracellular Ca2+. The results suggest that U-937 cell adhesion may be controlled by a protein kinase C isoform not sensitive to the inhibitors. In addition, the data indicate that selective pharmacological interference with different protein kinase C-mediated processes is achievable.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1993

Galanin-stimulated high-affinity GTPase activity in plasma membranes from RINm5F cells.

GTPase activity was studied in plasma membranes purified from the clonal beta-cell line RINm5F. GTPase activities were identified as two broad classes with high or low affinity for GTP. The low-affinity GTPase activity had a Km > 60 microM. In contrast, the high-affinity activity had a Km of 225 nM. Only the high-affinity activity was stimulated by galanin. The stimulated activity had a higher Km (448 nM) and Vmax (75 pmol P(i).min-1.mg-1 protein) compared with the basal. This does not necessarily reflect a complex mechanism of stimulation. Rather, it may reflect that basal activity most likely results from multiple GTPases, whereas the stimulated activity probably reflects one or two specific GTPases. Galanin stimulated the high-affinity GTPase, over the concentration range in which it inhibits stimulated insulin secretion, to a maximal rate 80% greater than the basal rate. The EC50 was 5 nM. Murine and porcine galanin had similar potencies and intrinsic activities on the GTPase. Treatment of the RINm5F cells with PTX before making membranes completely eliminated the stimulatory effect of galanin. Thus, galanin stimulates PTX-sensitive GTPase activity in RINm5F cell membranes in a manner consistent with receptor activation.

Animals↗

PubMed1992

Protein kinase C activity in rat renal proximal tubule cells.

The presence of protein kinase C (PKC) in proximal tubule cells of the rat kidney is established by means of immunodetection and by the demonstration of calcium- and phospholipid-dependent, staurosporine-inhibitable histone phosphorylation. The calcium-dependence of renal PKC is described. Maximal activation of the enzyme (178.2 and 258.8 pmol P1 mg-1 min-1 for cytosol and membrane respectively) was achieved with 5 microM of Ca2+. Phorbol 12, 13 dibutyrate (PDBu) translocated PKC from cytosol to membrane in a dose- and time-dependent fashion, while 4 alpha-phorbol 12,13-didecanoate produced no significant effect on translocation. Cytosolic PKC activity was compared in immature and mature tissues (10- and 40-day-old kidneys). Basal activity was found to be significantly higher (P less than 0.05) in immature cells (272.8 vs. 157.5 pmol Pi mg-1 min-1). PDBu at 10(-6) M for 15 min reduced immunoreactivity in the soluble fraction of both groups, which was accompanied by a significant decrease in kinase activity. We speculate that the high PKC activity in the infant kidney plays a role in cell growth.

Aging↗

PubMed1992

Pancreastatin inhibits insulin secretion from isolated rat islets: studies on its mechanism of action.

The peptide pancreastatin is known to inhibit insulin secretion. To study its mechanism of action, we examined the effects of pancreastatin on 45Ca(2+)- and 86Rb(+)-efflux from isolated rat islets. We found that glucose (8.3 mmol/l)-stimulated insulin secretion was totally abolished by pancreastatin (100 nmol/l). It is known that glucose reduces the 86Rb(+)-efflux and increases the 45Ca(2+)-efflux from prelabelled islets, which reflects its action on the K(+)- and Ca(2+)-permeabilities. We found that pancreastatin reduced the glucose-stimulated increase in 45Ca(2+)-efflux without affecting the 86Rb(+)-efflux. This shows that pancreastatin inhibits the action of glucose on Ca(2+)-channels, without influencing the closure of K(+)-channels induced by the sugar. The results indicate that pancreastatin does not inhibit insulin secretion by hyperpolarizing the B-cells, but rather that the peptide inhibits insulin secretion by inhibiting the glucose-stimulated B-cell Ca(2+)-uptake that evolves by depolarization.

Animals↗

PubMed1991

Intracellular mechanisms involved in leukotriene C4-stimulated adhesion of U-937 cells.

Leukotrienes C4 and D4 (LTC4 and LTD4) stimulated, 5- to 6-fold, the adhesion of the monoblastoid cell line U-937 to plastic. Half-maximal effects were observed around 1 nM. Leukotrienes E4 and B4 (LTE4 and LTB4) were less effective. The adhesive response to LTC4 was inhibited by pertussis toxin and was completely dependent on the presence of extracellular Ca2+. The LTC4-stimulated increases in inositol-phosphates and in intracellular Ca(2+)-concentration were insensitive to pertussis toxin. Activation of leukocyte adhesion is a novel action of cysteinyl-leukotrienes and the present study suggests that control of U-937-cell adhesion by LTC4 involves two pathways; one pertussis toxin insensitive pathway regulating intracellular Ca2+ in a manner partly dependent on extracellular Ca2+ and one pertussis toxin sensitive pathway not concerned with Cai(2+)-regulation.

Calcium↗

PubMed1991

Comparison of effects of neuropeptide Y and norepinephrine on insulin secretion and vascular resistance in perfused rat pancreas.

Neuropeptide Y (NPY) and norepinephrine (NE) behave like cotransmitters in intrapancreatic adrenergic nerves. Therefore, in the isolated rat pancreas, we 1) studied and compared the effect of increasing concentrations of NE and NPY given alone on insulin secretion induced by 8.3 mM glucose and on pancreatic vascular flow rate and 2) investigated the effects of combinations of NPY and NE at low concentrations. NE induced a dose-dependent inhibition of insulin release between 1 and 50 nM (max 80%); beta-cells appeared sensitive to NPY at 0.1 nM, but the maximal reduction of insulin release was comparatively weak (25-30%) at 10 nM. The study of the effect of combinations of NE and NPY at different concentrations suggests that the two neurotransmitters act in an additive way to inhibit insulin secretion. NPY (0.1-10 nM) induced a marked dose-dependent reduction of pancreatic outflow rate with a biphasic pattern between 1 and 10 nM. On the other hand, at low concentrations (1 and 2 nM), NE induced a progressive increase in pancreatic outflow rate; a clear but transient decrease could only be observed at 50 nM before a secondary increase. A combined treatment with two effective concentrations of NPY (0.1 nM) and NE (1 nM) resulted in a progressive reversal by NE of NPY's vasoconstrictive effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗