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1.
Transplant Proc ; 49(10): 2333-2339, 2017 Dec.
Article in English | MEDLINE | ID: mdl-29198673

ABSTRACT

BACKGROUND: Total pancreatectomy (TP) is offered as a last treatment option for pain relief in patients with chronic pancreatitis. Concurrent islets autotransplantation (TP-IAT) may improve glucose control. METHODS: We analyzed results in 20 recent patients who underwent TP-IAT at The University of Chicago. The median observation period was 28 months (2-38). Data were collected prospectively then analyzed retrospectively. RESULTS: The number of patients requiring opioids daily for pain control decreased from 16 (80%) prior to surgery to 2 (13%) 1 year after, with only 1 (6.5%) patient experiencing persistent phantom pancreatic pain. Opioid requirements decreased from a median 56.3 (0-240) morphine equivalent dose to 5 (0-130) on day 75 and to 0 (0-30) at 1-year follow up. Five patients (25%) completely stopped insulin support prior to day 75 while maintaining hemoglobin A1c of 5.9% (5-6.3). Eight (53%) patients were insulin free at 1 year with A1c of 6% (5.5-6.8) and a similar rate persisted in next 2 years. For the remaining patients, the more islet function that was preserved, the less insulin they required and A1c was closer to optimal. Quality of Life (QoL) measured by SF36 Physical (PCS) and Mental (MCS) Component Score improved on day 75 (P < .001) and maintained improvement later on. Both PCS and MCS improved regardless of whether patient requires insulin support or not. CONCLUSIONS: Improvements of QoL with pain resolution and good glucose control can be achieved after TP-IAT in properly selected patients with CP and intractable pain, regardless of patient insulin support status.


Subject(s)
Blood Glucose , Islets of Langerhans Transplantation/methods , Pain, Postoperative/epidemiology , Pancreatectomy/adverse effects , Pancreatitis, Chronic/surgery , Quality of Life , Adult , Female , Humans , Islets of Langerhans Transplantation/adverse effects , Male , Middle Aged , Pain Management , Pancreatectomy/methods , Retrospective Studies , Transplantation, Autologous , Treatment Outcome
2.
Transplant Proc ; 49(10): 2340-2346, 2017 Dec.
Article in English | MEDLINE | ID: mdl-29198674

ABSTRACT

BACKGROUND: BETA-2 score using a single fasting blood sample was developed to estimate beta-cell function after islet transplantation (ITx) and was validated internally by a high ITx volume center (Edmonton). The goal was to validate BETA-2 externally, in our center. METHODS: Areas under receiver operating characteristic curves (AUROCs) were obtained to see if beta score or BETA-2 would better detect insulin independence and glucose intolerance. RESULTS: We analyzed values from 48 mixed meal tolerance tests (MMTTs) in 4 ITx recipients with a long-term follow-up to 140 months (LT group) and from 54 MMTTs in 13 short-term group patients (ST group). AUROC for no need for insulin support was 0.776 (95% confidence interval [CI] 0.539-1, P = .02) and 0.922 (95% CI 0.848-0.996, P < .001) for beta score and 0.79 (95% CI 0.596-0.983, P = .003) and 0.941 (95% CI 0.86-1, P < .001) for BETA-2, in LT and ST groups, respectively, and did not differ significantly. In LT group BETA-2 score ≥ 13.03 predicted no need for insulin supplementation with sensitivity of 98%, specificity of 50%, positive predictive value (PPV) of 93%, and negative predictive value (NPV) of 75%. In ST group the optimal cutoff was ≥13.63 with sensitivity of 92% and specificity, PPV, and NPV 82% to 95%. For the detection of glucose intolerance BETA-2 cutoffs were <19.43 in LT group and <17.23 in ST group with sensitivity > 76% and specificity, PPV, and NPV > 80% in both groups. CONCLUSION: BETA-2 score was successfully validated externally and is a practical tool allowing for frequent and reliable assessments of islet graft function based on a single fasting blood sample.


Subject(s)
Blood Glucose/analysis , C-Peptide/analysis , Hypoglycemic Agents/therapeutic use , Insulin/therapeutic use , Islets of Langerhans Transplantation , Adult , Area Under Curve , Diabetes Mellitus, Type 1/surgery , Female , Glycated Hemoglobin/analysis , Humans , Male , Middle Aged , Predictive Value of Tests , ROC Curve
3.
Diabet Med ; 33(10): 1380-6, 2016 10.
Article in English | MEDLINE | ID: mdl-27223594

ABSTRACT

AIMS: KCNJ11-related diabetes is the most common form of permanent neonatal diabetes and has been associated with a spectrum of neurodevelopmental problems. We compared neurodevelopmental outcomes in patients with KCNJ11 mutations and their sibling controls. METHODS: Through our Monogenic Diabetes Registry (http://monogenicdiabetes.uchicago.edu/), we evaluated 23 patients with KCNJ11 mutations with (n = 9) and without (n = 14) global developmental delay successfully treated with sulfonylurea and 20 healthy sibling controls, using a battery of targeted neuropsychological and behavioural assessments with scaled scores that are comparable across a wide range of ages. RESULTS: Patients with KCNJ11-related diabetes without global developmental delay had significant differences compared with sibling controls on a range of assessments including IQ, measures of academic achievement and executive function. KCNJ11 patients with global delay exhibited significant differences in behavioural symptoms with a tendency to avoid social contact and displayed a reduced ability to adapt to new circumstances. Parents reported more immature behaviour, gross mood swings, bizarre thoughts, other unusual and severe behaviours, and there were also significant deficits in all subdomains of daily living skills. CONCLUSIONS: This series represents the largest and most comprehensive study of neuropsychological and behavioural dysfunction of individuals with KCNJ11 diabetes and is the first to compare outcome with sibling controls. Our data demonstrate the variety of neurodevelopmental problems seen in those with KCNJ11 mutations, even in those without recognized global developmental delays. These data can be used to counsel families and guide structured neurodevelopmental assessments and treatments based on the initial genetic diagnosis in patients with neonatal diabetes.


Subject(s)
Developmental Disabilities/genetics , Diabetes Mellitus/genetics , Diabetes Mellitus/psychology , Potassium Channels, Inwardly Rectifying/genetics , Adolescent , Amino Acid Substitution , Case-Control Studies , Child , Child, Preschool , Developmental Disabilities/diagnosis , Diabetes Mellitus/classification , Female , Humans , Infant , Infant, Newborn , Infant, Newborn, Diseases/genetics , Infant, Newborn, Diseases/psychology , Male , Mutation, Missense , Neurologic Manifestations , Neuropsychological Tests , Siblings
4.
Diabetes Metab ; 42(3): 157-61, 2016 Jun.
Article in English | MEDLINE | ID: mdl-26827115

ABSTRACT

Pancreatic beta-cells play a pivotal role to synthesize and secrete insulin, as the solo source of the body. Physical as well as functional loss of beta-cells over a certain threshold result in diabetes. While the mechanisms underlying beta-cell loss in various types of diabetes have been extensively studied, less is known about residual beta-cells, found even in autoimmune type 1 diabetes and type 2 diabetes with a substantial amount. Why have these beta-cells been spared? Some patients with neonatal diabetes have demonstrated the life-changing restoration of functional beta-cells that were inactive for decades but awakened in several weeks following specific treatment. The recent striking outcomes of bariatric surgery in many obese diabetic patients indicate that their beta-cells are likely "preserved" rather than irreversibly lost even in the multifactorial polygenic state that is type 2 diabetes. Collectively, the preservation of residual beta-cells in various diabetic conditions challenges us regarding our understanding of beta-cell death and survival, where their sustenance may stem from the existence of resting beta-cells under physiological conditions. We posit that beta-cells rest and that studies of this normal feature of beta-cells could lead to new approaches for potentially reactivating and preserving beta-cell mass in order to treat diabetes.


Subject(s)
Diabetes Mellitus, Type 1/pathology , Diabetes Mellitus, Type 2/pathology , Insulin-Secreting Cells/pathology , Insulin-Secreting Cells/physiology , Animals , Cell Count , Cell Cycle , Cytoprotection , Humans , Insulin/metabolism , Insulin Secretion , Regeneration/physiology
5.
Islets ; 5(1): 1-15, 2013.
Article in English | MEDLINE | ID: mdl-23624892

ABSTRACT

In mammals an increase in glucose leads to block of ATP dependent potassium channels in pancreatic ß cells leading to membrane depolarization. This leads to the repetitive firing of action potentials that increases calcium influx and triggers insulin granule exocytosis. Several important differences between species in this process suggest that a dedicated human-oriented approach is advantageous as extrapolating from rodent data may be misleading in several respects. We examined depolarization-induced spike activity in pancreatic human islet-attached ß-cells employing whole-cell patch-clamp methods. We also reviewed the literature concerning regulation of insulin secretion by channel activity and constructed a data-based computer model of human ß cell function. The model couples the Hodgkin-Huxley-type ionic equations to the equations describing intracellular Ca²âº homeostasis and insulin release. On the basis of this model we employed computational simulations to better understand the behavior of action potentials, calcium handling and insulin secretion in human ß cells under a wide range of experimental conditions. This computational system approach provides a framework to analyze the mechanisms of human ß cell insulin secretion.


Subject(s)
Insulin-Secreting Cells/metabolism , Insulin/metabolism , Ion Channels/metabolism , Models, Biological , Secretory Pathway , Animals , Calcium Signaling , Computer Simulation , Humans , Insulin Secretion , Species Specificity
6.
Pediatr Diabetes ; 14(2): 90-6, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23350725

ABSTRACT

Recent results of genome wide association study (GWAS) for diabetes genes, while reaching impressive technical milestones and implicating new findings for research, have been uniformly disappointing in terms of immediate clinical utility. The relative risk associated with any of the newly reported genetic loci, or even considering all of them together, is far less than simply that which can be obtained by taking a history and a physical exam. For type 2 diabetes (T2D), GWAS have implicated novel pathways, supported previously known associations, and highlighted the importance of the beta cell and insulin secretion. Monogenic forms of diabetes, on the other hand, continue to yield interesting insights into genes controlling human beta cell function but most cases of monogenic diabetes are simply not diagnosed. Here, we briefly review recent results related to type 1, type 2 and maturity onset diabetes of youth (MODY) diabetes and suggest that future studies emphasizing quantitative traits are likely to yield even more insights.


Subject(s)
Diabetes Mellitus, Type 1/genetics , Diabetes Mellitus, Type 2/genetics , Genome-Wide Association Study , Humans , Linkage Disequilibrium , Polymorphism, Single Nucleotide , Quantitative Trait Loci
7.
Am J Physiol Endocrinol Metab ; 299(4): E517-32, 2010 Oct.
Article in English | MEDLINE | ID: mdl-20628025

ABSTRACT

Oscillatory phenomenon in electrical activity and cytoplasmic calcium concentration in response to glucose are intimately connected to multiple key aspects of pancreatic ß-cell physiology. However, there is no single model for oscillatory mechanisms in these cells. We set out to identify possible pacemaker candidates for burst activity and cytoplasmic Ca(2+) oscillations in these cells by analyzing published hypotheses, their corresponding mathematical models, and relevant experimental data. We found that although no single pacemaker can account for the variety of oscillatory phenomena in ß-cells, at least several separate mechanisms can underlie specific kinds of oscillations. According to our analysis, slowly activating Ca(2+)-sensitive K(+) channels can be responsible for very fast Ca(2+) oscillations; changes in the ATP/ADP ratio and in the endoplasmic reticulum calcium concentration can be pacemakers for both fast bursts and cytoplasmic calcium oscillations, and cyclical cytoplasmic Na(+) changes may underlie patterning of slow calcium oscillations. However, these mechanisms still lack direct confirmation, and their potential interactions raises new issues. Further studies supported by improved mathematical models are necessary to understand oscillatory phenomena in ß-cell physiology.


Subject(s)
Calcium Signaling/physiology , Glucose/physiology , Insulin-Secreting Cells/physiology , Potassium Channels, Voltage-Gated/physiology , Animals , Cell Membrane/physiology , Humans , Models, Biological
8.
Diabetes Obes Metab ; 11 Suppl 4: 189-96, 2009 Nov.
Article in English | MEDLINE | ID: mdl-19817801

ABSTRACT

The preeminent role of the beta cell is to manufacture, store and release insulin. The mature insulin molecule is composed of two polypeptide chains designated as A and B that are joined by two pairs of disulfide bonds with an additional intramolecular disulfide bond in the A chain. However, the two chains of the insulin molecule are not synthesized as separate polypeptide chains but rather are generated by specific proteolytic processing of a larger precursor, proinsulin. This discovery in 1967 and the concept of prohormones changed our view of the biosynthesis of hormones and neuropeptides. It allowed studies of the regulation of insulin biosynthesis that highlighted the key role of glucose. In addition, the C-peptide, the polypeptide that joins the A and B chains in proinsulin and is stored with insulin in the secretory granules and secreted in equimolar amounts, allowed studies of pancreatic beta cell function in vivo including in patients with diabetes. Subsequent studies have identified the specific proteases, prohormone convertases 1/3 and 2 and carboxypeptidase E, that are involved in the conversion of proinsulin to proinsulin intermediates and then to insulin. Disorders of (pro)insulin biosynthesis continue to illuminate important aspects of this pathway, revealing important connections to diabetes pathogenesis. Recent studies of patients with insulin gene mutations that cause permanent neonatal diabetes have identified key residues affecting the folding and structural organization of the preproinsulin molecule and its subsequent processing. These findings have renewed interest in the key role of endoplasmic reticulum function in insulin biosynthesis and the maintainance of normal beta cell health.


Subject(s)
C-Peptide/metabolism , Diabetes Mellitus, Type 2/metabolism , Insulin-Secreting Cells/metabolism , Insulin/biosynthesis , Diabetes Mellitus, Type 2/genetics , Humans , Insulin/genetics , Proinsulin/biosynthesis , Proinsulin/genetics
9.
Biophys J ; 96(8): 3126-39, 2009 Apr 22.
Article in English | MEDLINE | ID: mdl-19383458

ABSTRACT

We examined the ionic mechanisms mediating depolarization-induced spike activity in pancreatic beta-cells. We formulated a Hodgkin-Huxley-type ionic model for the action potential (AP) in these cells based on voltage- and current-clamp results together with measurements of Ca(2+) dynamics in wild-type and Kv2.1 null mouse islets. The model contains an L-type Ca(2+) current, a "rapid" delayed-rectifier K(+) current, a small slowly-activated K(+) current, a Ca(2+)-activated K(+) current, an ATP-sensitive K(+) current, a plasma membrane calcium-pump current and a Na(+) background current. This model, coupled with an equation describing intracellular Ca(2+) homeostasis, replicates beta-cell AP and Ca(2+) changes during one glucose-induced spontaneous spike, the effects of blocking K(+) currents with different inhibitors, and specific complex spike in mouse islets lacking Kv2.1 channels. The currents with voltage-independent gating variables can also be responsible for burst behavior. Original features of this model include new equations for L-type Ca(2+) current, assessment of the role of rapid delayed-rectifier K(+) current, and Ca(2+)-activated K(+) currents, demonstrating the important roles of the Ca(2+)-pump and background currents in the APs and bursts. This model provides acceptable fits to voltage-clamp, AP, and Ca(2+) concentration data based on in silico analysis.


Subject(s)
Action Potentials , Calcium Signaling , Insulin-Secreting Cells/physiology , Models, Neurological , Adenosine Triphosphate/metabolism , Animals , Calcium/metabolism , Calcium Channels, L-Type/metabolism , Cell Membrane/physiology , Computer Simulation , Delayed Rectifier Potassium Channels/metabolism , Glucose/metabolism , Mice , Mice, Knockout , Patch-Clamp Techniques , Potassium/metabolism , Potassium Channels, Voltage-Gated/antagonists & inhibitors , Shab Potassium Channels/genetics , Sodium/metabolism , Tetraethylammonium/pharmacology , Time
10.
Curr Top Microbiol Immunol ; 323: 67-87, 2008.
Article in English | MEDLINE | ID: mdl-18357766

ABSTRACT

The coxsackievirus and adenovirus receptor (CAR) has been studied extensively since its identification and isolation in 1997. The CAR is an immunoglobulin superfamily protein with two extracellular Ig-like domains, a single membrane-spanning sequence, and a significant cytoplasmic domain. It is structurally and functionally similar to the junctional adhesion molecules. The amino terminal domain, distal from the membrane, has been structurally characterized alone, bound to the adenovirus fiber knob, and, in full-length CAR, docked in the canyon structure of the coxsackievirus capsid. Although the past decade has produced a burst of new knowledge about CAR, significant questions concerning its function in normal physiology and coxsackievirus-related pathology remain unanswered.


Subject(s)
Coxsackievirus Infections/virology , Enterovirus B, Human/metabolism , Membrane Proteins/metabolism , Receptors, Virus/chemistry , Receptors, Virus/metabolism , Animals , Coxsackie and Adenovirus Receptor-Like Membrane Protein , Enterovirus B, Human/ultrastructure , Humans , Protein Conformation , Protein Structure, Tertiary , Receptors, Virus/genetics
11.
Diabetes Obes Metab ; 9 Suppl 2: 89-98, 2007 Nov.
Article in English | MEDLINE | ID: mdl-17919183

ABSTRACT

Coordinated electrical activity allows pancreatic beta-cells to respond to secretagogues with calcium entry followed by insulin secretion. Metabolism of glucose affects multiple membrane proteins including ion channels, transporters and pumps that collaborate in a cascade of electrical activity resulting in insulin release. Glucose induces beta-cell depolarization resulting in the firing of action potentials (APs), which are the primary electrical signal of the beta-cell. They are shaped by orchestrated activation of ion channels. Here we give an overview of the voltage-gated potassium (Kv) channels of the beta-cell, which are responsible in part for the falling phase of the AP, and how their regulation affects insulin secretion. beta cells contain several Kv channels allowing dynamic integration of multiple signals on repolarization of glucose-stimulated APs. Recent studies on Kv channel regulation by cAMP and arachidonic acid and on the Kv2.1 null mouse have greatly increased our understanding of beta-cell excitation-secretion coupling.


Subject(s)
Action Potentials , Insulin/metabolism , Ion Channels/physiology , Islets of Langerhans/physiology , Potassium Channels, Inwardly Rectifying , Animals , Calcium Channels/physiology , Insulin Secretion , Mice , Potassium Channels/physiology , Potassium Channels, Voltage-Gated , Sodium Channels/physiology
12.
Z Gerontol Geriatr ; 40(4): 209-16, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17701112

ABSTRACT

In Denmark, political decisions improved the implementation of 'preventative thinking' into every-day clinical work. The potential benefits of preventive efforts have been supported by legislative and administrative incentives, and an ongoing effort to remain focused on the benefits of these initiatives towards older people is politically formulated and underlined as part of the new structured municipality reform. Evidence of beneficial effects of health promotion and prevention of disease in old age is well documented. In-home visits with individualised assessments make it possible to reach older persons not normally seen in the health care system. In-home assessment is not just a health check, but also an opportunity to meet individual needs that may be of importance for older people to stay independent. Preventive home visits may be part of an overall culture and strategy to avoid or prevent functional decline. There is an urgent need of an interdisciplinary teamwork and management for such programmes, incorporating flexible cooperation between the primary and secondary health care sector. The value and importance of geriatric and gerontological education is evidence based.


Subject(s)
Chronic Disease/prevention & control , House Calls , National Health Programs/legislation & jurisprudence , Patient Care Team/legislation & jurisprudence , Activities of Daily Living/classification , Aged , Aged, 80 and over , Denmark , Geriatric Assessment , Humans , Needs Assessment/legislation & jurisprudence
13.
Handb Exp Pharmacol ; (179): 409-24, 2007.
Article in English | MEDLINE | ID: mdl-17217070

ABSTRACT

Orchestrated ion fluctuations within pancreatic islets regulate hormone secretion and maybe essential to processes such as apoptosis. A diverse set of ion channels allows for islet cells to respond to a variety of signals and dynamically regulate hormone secretion and glucose homeostasis (reviewed by Houamed et al. 2004). This chapter focuses on transient receptor potential (TRP)-related channels found within the beta cells of the islet and reviews their roles in both insulin secretion and apoptosis.


Subject(s)
Insulin-Secreting Cells/physiology , Transient Receptor Potential Channels/physiology , Animals , Humans , Insulin-Secreting Cells/drug effects , Insulin-Secreting Cells/metabolism , Ion Channels/drug effects , Ion Channels/metabolism , Ion Channels/physiology , Neurosecretory Systems/drug effects , Neurosecretory Systems/physiology , Transient Receptor Potential Channels/antagonists & inhibitors , Transient Receptor Potential Channels/metabolism
14.
Am J Transplant ; 6(12): 2861-70, 2006 Dec.
Article in English | MEDLINE | ID: mdl-17062000

ABSTRACT

During isolation, islets are exposed to warm ischemia. In this study, intraductal administration of oxygenated polymerized, stroma-free hemoglobin-pyridoxalated (Poly SFH-P) was performed to improve O2 delivery. Rat pancreata subjected to 30-min warm ischemia were perfused intraductally with collagenase in oxygenated Poly SFH-P/RPMI or RPMI (control). PO2 was increased by Poly SFH-P (381.7 +/- 35.3 mmHg vs. 202.3 +/- 28.2, p = 0.01) and pH maintained within physiological range (7.4-7.2 vs. 7.1-6.6, p = 0.009). Islet viability (77% +/- 4.6 vs. 63% +/- 4.7, p = 0.04) was improved and apoptosis lower with Poly SFH-P (caspase-3: 34,714 +/- 2167 vs. 45,985 +/- 1382, respectively, p = 0.01). Poly SFH-P improved islet responsiveness to glucose as determined by increased intracellular Ca2+ levels and improved insulin secretion (SI 5.4 +/- 0.1 vs. 3.1 +/- 0.2, p = 0.03). Mitochondrial integrity was improved in Poly SFH-P-treated islets, which showed higher percentage change in membrane potential after glucose stimulation (14.7% +/- 1.8 vs. 9.8 +/- 1.4, respectively, p < 0.05). O2 delivery by Poly SFH-P did not increase oxidative stress (GSH 7.1 +/- 2.9 nm/mg protein for Poly SFH-P vs. 6.8 +/- 2.4 control, p = 0.9) or oxidative injury (MDA 1.8 +/- 0.9 nmol/mg protein vs. 6.2 +/- 2.4, p = 0.19). Time to reach normoglycemia in transplanted diabetic nude mice was shorter (1.8 +/- 0.4 vs. 7 +/- 2.5 days, p = 0.02), and glucose tolerance improved in the Poly SFH-P group (AUC 8106 +/- 590 vs. 10,863 +/- 946, p = 0.03). Oxygenated Poly SFH-P improves islet isolation and transplantation outcomes by preserving mitochondrial integrity.


Subject(s)
Blood Substitutes/pharmacology , Hemoglobins/pharmacology , Islets of Langerhans Transplantation/methods , Islets of Langerhans Transplantation/physiology , Islets of Langerhans/cytology , Pyridoxal Phosphate/analogs & derivatives , Animals , Apoptosis , Calcium/metabolism , Cell Separation/methods , Glucose/metabolism , Glucose/pharmacology , Islets of Langerhans/drug effects , Membrane Potentials , Mice , Mice, Nude , Mitochondrial Membranes/drug effects , Mitochondrial Membranes/physiology , Oxidative Stress/drug effects , Pyridoxal Phosphate/pharmacology , Rats , Tolbutamide/pharmacology , Transplantation, Heterologous
15.
Diabetes Obes Metab ; 8(2): 136-45, 2006 Mar.
Article in English | MEDLINE | ID: mdl-16448517

ABSTRACT

The early stages of type 2 diabetes mellitus are characterized by the development of insulin resistance (IRe) in muscle cells and adipocytes with the concomitant loss of beta-cell compensation. We have extensively reviewed the literature related to metabolic and signalling pathways of reactive oxygen species (ROS) in regard to the coordinated development of oxidative stress and IRe. We considered the hypothesis that oxidative stress leads to IRe in muscle cells and adipocytes, but found that the data are more consistent with the hypothesis that the cellular mechanisms that protect against oxidative stress per se are capable of creating an ROS-dependent insulin-resistant state. Furthermore, ROS-induced mitochondrial dysfunction can lead to disruptions of lipid metabolism, increasing the intracellular lipid content, and, in addition, contribute to lipid-dependent IRe in myocytes. Together, these two ROS-activated pathways to IRe can contribute to a global state of profound resistance to insulin action. Therapeutic strategies should, therefore, be directed towards reducing insulin resistance without an increase in ROS production or concentration. Pharmacological or other approaches to IRe that result in the activation of mitochondrial biogenesis in particular could be highly beneficial in the prevention or treatment of both insulin resistance and type 2 diabetes.


Subject(s)
Diabetes Mellitus, Type 2/metabolism , Reactive Oxygen Species/metabolism , Adipocytes/metabolism , Humans , Insulin/metabolism , Insulin Resistance/physiology , Lipid Metabolism , Muscle, Skeletal/metabolism , Oxidative Stress/physiology
16.
J Endocrinol ; 185(1): 57-67, 2005 Apr.
Article in English | MEDLINE | ID: mdl-15817827

ABSTRACT

Several proteins play a role in the mechanism of insulin exocytosis. However, these 'exocytotic proteins' have yet to account for the regulated aspect of insulin exocytosis, and other factors are involved. In pancreatic exocrine cells, the intralumenal zymogen granule protein, syncollin, is required for efficient regulated exocytosis, but it is not known whether intragranular peptides similarly influence regulated insulin exocytosis. Here, this issue has been addressed using expression of syncollin and a syncollin-green fluorescent protein (syncollinGFP) chimera in rat islet beta-cells as experimental tools. Syncollin is not normally expressed in beta-cells but adenoviral-mediated expression of both syncollin and syncollinGFP indicated that these were specifically targeted to the lumen of beta-granules. Syncollin expression in isolated rat islets had no effect on basal insulin secretion but significantly inhibited regulated insulin secretion stimulated by glucose (16.7 mM), glucagon-like peptide-1 (GLP-1) (10 nM) and glyburide (5 microM). Consistent with specific localization of syncollin to beta-granules, constitutive secretion was unchanged by syncollin expression in rat islets. Syncollin-mediated inhibition of insulin secretion was not due to inadequate insulin production. Moreover, secretagogue-induced increases in cytosolic intracellular Ca2+, which is a prerequisite for triggering insulin exocytosis, were unaffected in syncollin-expressing islets. Therefore, syncollin was most likely acting downstream of secondary signals at the level of insulin exocytosis. Thus, syncollin expression in beta-cells has highlighted the importance of intralumenal beta-granule peptide factors playing a role in the control of insulin exocytosis. In contrast to syncollin, syncollinGFP had no effect on insulin secretion, underlining its usefulness as a 'fluorescent tag' to track beta-granule transport and exocytosis in real time.


Subject(s)
Carrier Proteins/metabolism , Insulin/metabolism , Islets of Langerhans/metabolism , Membrane Proteins/metabolism , Animals , Carrier Proteins/genetics , Cell Line , Exocytosis , Glucagon/pharmacology , Glucagon-Like Peptide 1 , Glucose/pharmacology , Glyburide/pharmacology , Green Fluorescent Proteins/genetics , Humans , Insulin Secretion , Membrane Proteins/genetics , Microscopy, Confocal , Microscopy, Fluorescence , Peptide Fragments/pharmacology , Protein Precursors/pharmacology , Rats , Rats, Sprague-Dawley , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Stimulation, Chemical
17.
Transplant Proc ; 36(4): 1031-3, 2004 May.
Article in English | MEDLINE | ID: mdl-15194358

ABSTRACT

INTRODUCTION: Clinical islet transplantation is increasingly regulated, with isolation standards defined under current good manufacturing practices (cGMPs). cGMP requires validation of equipment cleaning and sterilization. The automated process for islet isolation requires rapid thermal exchange during processing, manipulating a metal coil containing cellular product into and out of chilled/heated waterbaths. We recognize challenges of validating cleaning and sterilization of this coil and propose replacement with a disposable blood warming system. Our specific aims were to assess the system's ability to accommodate flow rates utilized during various phases of pancreatic digestion and to assess its efficiency of heat exchange and temperature control. METHODS: In a pancreas digestion circuit, heat exchange occurred via the coil in a digital water bath, or Warmflo blood warming bag in a digital warming unit. Temperature within the digestion chamber was assessed using an inserted thermocouple. Time to achieve 37 degrees C was measured for set heating element temperatures 38.5 degrees C to 41 degrees C. Circuit temperature maintenance characteristics were also recorded. RESULTS: The Warmflo bloodbag easily accommodated flows of 150 and 300 mL/min. At all set temperatures, the bag resulted in shorter or equivalent time to 37 degrees C than the coil. Maintenance of 37 degrees C was also equivalent. We have utilized this system for four human islet isolations with mean time to 37 degrees C of 5.5 minutes, without difference in digestion quality. CONCLUSIONS: Use of a disposable blood warming system in place of the coil during islet isolation provides adequate flow characteristics, heat exchange, and temperature control and may facilitate evolution of islet isolation toward cGMP compliance.


Subject(s)
Cyclic GMP/pharmacology , Islets of Langerhans/cytology , Cell Culture Techniques/methods , Cell Separation/methods , Humans , Islets of Langerhans/drug effects , Islets of Langerhans Transplantation/physiology , Temperature , Thermodynamics
18.
Curr Top Microbiol Immunol ; 273: 87-111, 2004.
Article in English | MEDLINE | ID: mdl-14674599

ABSTRACT

The physiological and cell biological aspects of the Coxsackie-Adenovirus Receptor (CAR) is discussed in this review. The receptor obviously recognizes the group C adenoviruses in vivo, but also fibers from other groups except group B in vitro. The latter viruses seem to utilize a different receptor. The receptor accumulates at, or close to, the tight junction in polarized epithelial cells and probably functions as a cell-cell adhesion molecule. The cytoplasmic tail of the receptor is not required for virus attachment and uptake. Although there is a correlation between CAR and uptake of adenoviruses in several human tumor cells, evidence of an absolute requirement for integrins has not been forthcoming. The implication of these findings for adenovirus gene therapy is discussed.


Subject(s)
Adenoviridae/physiology , Receptors, Virus/physiology , Adenoviridae/genetics , Animals , Cell Adhesion/physiology , Coxsackie and Adenovirus Receptor-Like Membrane Protein , Gene Expression Regulation , Humans , Receptors, Virus/genetics , Receptors, Virus/immunology
19.
J Allergy Clin Immunol ; 110(6 Suppl): S313-7, 2002 Dec.
Article in English | MEDLINE | ID: mdl-12464941

ABSTRACT

This review presents recent concepts of how beta-agonists affect glucose homeostasis by modulating insulin secretion, liver metabolism, and uptake of glucose into muscle, with attention to the influence of hypoglycemia on beta-agonist sensitivity and the effects of beta(3)-adrenergic receptor (beta(3)AR) polymorphisms on adipocyte metabolism. Specific beta(2)-agonist effects on the pancreatic beta cell result in increased insulin secretion, yet other mechanisms, such as increased glucagon secretion and hepatic effects, cause an overall increase in serum glucose and an apparent decrease in insulin sensitivity. Human studies confirm the presence of beta(2)ARs on pancreatic beta cells. Intensive treatment of diabetes mellitus with insulin, especially in type 1 diabetes, has led to increased incidence of hypoglycemia. Repeated episodes of hypoglycemia lead to unawareness of neuroglycopenia, a major limitation to intensive treatment. Hypoglycemic unawareness is associated with reduced beta-agonist sensitivity. Scrupulous avoidance of hypoglycemia over many weeks to months can restore beta-agonist sensitivity and improve detection of hypoglycemia. beta-agonists have also been employed to prevent hypoglycemia. beta-agonists can increase thermogenesis and lipolysis, leading to increased energy expenditure and decreased fat stores. While beta(1)ARs and beta(2)ARs mediate many of these actions, it is likely that beta(3)ARs in the adipocyte membrane also play an important role. Specific beta(3)AR subtypes have been associated with obesity and the metabolic syndrome.


Subject(s)
Adrenergic beta-2 Receptor Agonists , Adrenergic beta-Agonists/pharmacology , Glucose/metabolism , Insulin/metabolism , Adipose Tissue/drug effects , Homeostasis , Humans , Insulin Secretion , Liver/drug effects , Liver/metabolism , Muscle, Smooth/drug effects , Muscle, Smooth/metabolism
20.
Gene Ther ; 9(9): 547-53, 2002 May.
Article in English | MEDLINE | ID: mdl-11973630

ABSTRACT

The use of adenoviral vectors as potent gene delivery systems requires expression of the Coxsackievirus/adenovirus receptor (CVADR) on the target cell surface. This receptor is important for virus attachment to the cell surface. For effective internalization of the vector into the target cell the integrins alpha(v)beta(3) and/or alpha(v)beta(5) are needed. Since there have been reports of loss of CVADR in bladder cancer cell lines, we wanted to investigate the expression of this receptor in bladder carcinoma biopsies. Surgical biopsies, as well as five human bladder cancer cell lines, were analyzed for expression of CVADR, the integrins alpha(v)beta(3) and alpha(v)beta(5) and MHC class I. Further, we studied the ability to transduce these cell lines using adenoviral vectors. Immunohistochemistry revealed that all biopsies (27/27) were positive for CVADR. Some variation in expression was evident, and superficially growing tumors stained more strongly than invasive ones. Most human tumors expressed the integrin alpha(v)beta(5) (14/24), whereas integrin alpha(v)beta(3) was less frequently seen (3/20). The established cell lines were efficiently transduced with adenoviral vectors, and transduction could be reduced with anti-CVADR antibodies. The abundance of appropriate viral receptors on tumor biopsy cells is a further argument for using adenoviral vectors in gene therapy of bladder cancer.


Subject(s)
Adenoviridae , Carcinoma/chemistry , Enterovirus , Receptors, Virus/analysis , Urinary Bladder Neoplasms/chemistry , Adenoviridae/genetics , Antibodies, Monoclonal/pharmacology , Enterovirus/genetics , Genetic Therapy/methods , Genetic Vectors/administration & dosage , Humans , Integrins/analysis , Receptors, Virus/immunology , Receptors, Vitronectin/analysis , Transduction, Genetic/methods , Tumor Cells, Cultured
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