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1.
Diabet Med ; 37(5): 752-759, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31811662

RESUMO

AIM: To evaluate the effect of final HbA1c levels on the incidences of hypoglycaemia in participants with type 1 diabetes treated with inhaled Technosphere® Insulin or subcutaneous insulin aspart, reported in alignment with the International Hypoglycaemia Study Group recommendations. METHODS: In the randomized, phase 3, multicentre AFFINITY-1 study, adults (N = 375) who had type 1 diabetes for ≥ 12 months and an HbA1c level of 58-86 mmol/mol (7.5-10.0%) were randomized to receive basal insulin plus either inhaled Technosphere Insulin or subcutaneous insulin aspart. This was a post-hoc regression analysis on a subset (N = 279) of the randomized AFFINITY-1 cohort for whom baseline and end-of-treatment HbA1c values were reported. Primary outcome measures were incidence and event rates for levels 1, 2 and 3 hypoglycaemia, respectively defined as blood glucose levels of ≤ 3.9 mmol/l, < 3.0 mmol/l or requiring external assistance for recovery. RESULTS: Participants treated with Technosphere Insulin experienced statistically significantly fewer level 1 and 2 hypoglycaemic events and a lower incidence of level 3 hypoglycaemia than participants treated with insulin aspart. The lower rate of hypoglycaemia with Technosphere Insulin was observed across the range of end-of-treatment HbA1c levels. Technosphere Insulin was associated with higher rates of hypoglycaemia 30-60 min after meals, but significantly lower rates 2-6 h after meals. CONCLUSIONS: Participants using Technosphere Insulin experienced clinically non-inferior glycaemic control and lower hypoglycaemia rates across a range of HbA1c levels compared with participants receiving insulin aspart. ClinicalTrials.gov: NCT01445951.


Assuntos
Diabetes Mellitus Tipo 1/tratamento farmacológico , Hipoglicemia/induzido quimicamente , Hipoglicemiantes/administração & dosagem , Hipoglicemiantes/efeitos adversos , Insulina Aspart/efeitos adversos , Insulina/administração & dosagem , Insulina/efeitos adversos , Microesferas , Administração por Inalação , Adulto , Diabetes Mellitus Tipo 1/metabolismo , Feminino , Hemoglobinas Glicadas/metabolismo , Humanos , Masculino , Refeições
2.
Diabet Med ; 33(8): 1076-83, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-26261902

RESUMO

AIMS AND HYPOTHESIS: In patients with Type 2 diabetes, intensive glycaemic control is associated with hypoglycaemia and possibly increased mortality. However, no blood biomarkers exist to predict these outcomes. Using participants from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study, we hypothesized that insulin deficiency and islet autoantibodies in patients with clinically diagnosed Type 2 diabetes would be associated with severe hypoglycaemia and death. METHODS: A nested case-control study design was used. A case (n = 86) was a participant who died with at least one episode of severe hypoglycaemia, defined as hypoglycaemia requiring assistance, at any point during ACCORD follow-up. A control (n = 344) was a participant who did not die and did not have severe hypoglycaemia during follow-up. Each case was matched to four controls (glycaemic intervention arm, race, age and BMI). Baseline insulin deficiency (fasting C-peptide ≤ 0.15 nmol/l) and islet autoantibodies [glutamic acid decarboxylase (GAD), tyrosine phosphatase-related islet antigen 2 (IA2), insulin (IAA) and zinc transporter (ZnT8)] were measured. Conditional logistic regression with and without adjustment for age, BMI and diabetes duration was used. RESULTS: Death during ACCORD in those who experienced at least one episode of severe hypoglycaemia was associated with insulin deficiency [OR 4.8 (2.1, 11.1): P < 0.0001], GAD antibodies [OR 2.3 (1.1, 5.1): P = 0.04], the presence of IAA or baseline insulin use [OR 6.1 (3.5,10.7): P < 0.0001], which remained significant after adjusting for age, BMI, and diabetes duration. There was no significant association with IA2 or ZnT8 antibodies. CONCLUSIONS: In patients with Type 2 diabetes, C-peptide or GAD antibodies may serve as blood biomarkers predicting higher odds of subsequent severe hypoglycaemia and death. (Clinical Trial Registry No: NCT00000620, www.clinicaltrials.gov for original ACCORD study).


Assuntos
Autoanticorpos/sangue , Peptídeo C/sangue , Diabetes Mellitus Tipo 2/sangue , Hipoglicemia/sangue , Hipoglicemiantes/efeitos adversos , Insulina/sangue , Mortalidade , Idoso , Autoanticorpos/imunologia , Biomarcadores , Estudos de Casos e Controles , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/epidemiologia , Feminino , Glutamato Descarboxilase/imunologia , Humanos , Hipoglicemia/induzido quimicamente , Hipoglicemia/epidemiologia , Insulina/imunologia , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Proteínas Tirosina Fosfatases Classe 8 Semelhantes a Receptores/imunologia , Índice de Gravidade de Doença , Transportador 8 de Zinco/imunologia
3.
Diabetes Obes Metab ; 18(1): 92-5, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26435375

RESUMO

The aim of this study was to identify the clinical features of participants in the standard therapy arm of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) glycaemia trial who failed to reach the glycated haemoglobin (HbA1c) target. We analysed 4685 participants in the standard therapy arm, comparing participants who reached the HbA1c target of <8.0% with those whose HbA1c level was ≥8.0% 12 months after randomization. Baseline and 12-month clinical characteristics were compared. At 12 months after randomization, 3194 participants had HbA1c <8.0% and 1491 had HbA1c ≥8.0%. Black race [odds ratio (OR) 0.74, 95% confidence interval (CI) 0.61-0.89; p = 0.002], severe hypoglycaemia (OR 0.57, CI 0.37-0.89; p = 0.014) and insulin use (OR 0.51, CI 0.40-0.65; p < 0.001) were associated with failure to reach HbA1c goal at 12 months in the adjusted model. Even with free medications, free visits with clinicians and aggressive titration of medications, >30% of participants in the standard arm of the ACCORD trial had an HbA1c ≥8.0% at 1 year. Participants who were black, had severe hypoglycaemia and were on insulin were more likely to have an above-target HbA1c concentration after 12 months on the standard protocol.


Assuntos
Doenças Cardiovasculares/prevenção & controle , Diabetes Mellitus Tipo 2/sangue , Hemoglobinas Glicadas/análise , Hipoglicemiantes/uso terapêutico , Idoso , População Negra/estatística & dados numéricos , Glicemia/análise , Doenças Cardiovasculares/etiologia , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/etnologia , Quimioterapia Combinada , Feminino , Humanos , Hipoglicemia/induzido quimicamente , Insulina/efeitos adversos , Masculino , Pessoa de Meia-Idade , Valores de Referência , Fatores de Risco , Falha de Tratamento
4.
Magn Reson Med ; 71(1): 12-8, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23423963

RESUMO

PURPOSE: Hypothalamic GABA signaling has been shown to regulate the hormonal response to hypoglycemia in animals. The hypothalamus is a challenging brain region for magnetic resonance spectroscopy (MRS) due to its small size and central location. To investigate the feasibility of measuring GABA in the hypothalamus in humans, ultra-high field MRS was used. METHODS: GABA levels in the hypothalamus and occipital cortex (control region) were measured in healthy volunteers during euglycemia and hypoglycemia at 7 tesla using short-echo STEAM (TE = 8 ms, TR = 5 s). RESULTS: Hypothalamic GABA levels were quantified with a mean within-session test-retest coefficient of variance of 9%. Relatively high GABA levels were observed in the hypothalamus compared with other brain regions. Hypothalamic GABA levels were 3.5 ± 0.3 µmol/g during euglycemia (glucose 89 ± 6 mg/dL) vs. 3.0 ± 0.4 µmol/g during hypoglycemia (glucose 61 ± 3 mg/dL) (P = 0.06, N = 7). In the occipital cortex, GABA levels remained constant at 1.4 ± 0.4 vs.1.4 ± 0.3 µmol/g (P = 0.3, N = 5) as glucose fell from 91 ± 4 to 61 ± 4 mg/dL. CONCLUSION: GABA concentration can be quantified in the human hypothalamus and shows a trend toward decrease in response to an acute fall in blood glucose. These methods can be used to further investigate role of GABA signaling in the counterregulatory response to hypoglycemia in humans.


Assuntos
Glicemia/metabolismo , Hiperinsulinismo/metabolismo , Hipoglicemia/metabolismo , Hipotálamo/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Lobo Occipital/metabolismo , Ácido gama-Aminobutírico/metabolismo , Adulto , Feminino , Humanos , Insulina/sangue , Masculino , Projetos Piloto , Valores de Referência , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
5.
Minerva Med ; 101(2): 105-14, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20467409

RESUMO

Both type 1 and type 2 diabetes mellitus are known to cause widespread complications in numerous organ systems, including the brain. In this review we will discuss the structural changes that have been identified in humans with type 1 diabetes using magnetic resonance imaging. We will also review how diabetes, hyperglycemia, and hypoglycemia have been found to alter neurocognitive function in patients with this disease. Potential mechanisms that may underlie the development of the cerebral structural and function changes seen in patients with type 1 diabetes will then be presented.


Assuntos
Encefalopatias Metabólicas/patologia , Encéfalo/patologia , Diabetes Mellitus Tipo 1/patologia , Encefalopatias Metabólicas/etiologia , Transtornos Cognitivos/etiologia , Transtornos Cognitivos/patologia , Diabetes Mellitus Tipo 1/complicações , Humanos , Hiperglicemia/complicações , Hiperglicemia/patologia , Hipoglicemia/complicações , Hipoglicemia/patologia , Imageamento por Ressonância Magnética
6.
J Clin Invest ; 89(6): 1761-6, 1992 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-1601986

RESUMO

To assess the metabolic consequences of hemipancreatectomy in humans, we determined pancreatic beta and alpha cell function in healthy donors. Donors examined cross-sectionally were found to have significantly decreased glucose-induced phasic insulin secretion and arginine-induced insulin and glucagon secretion as compared to age, sex, and body index-matched controls. However, their fasting glucose and insulin values were not different from controls. Similar observations were found in the prospective evaluation of eight donors before and 15 +/- 2 mo after hemipancreatectomy. Beta cell reserve, as measured by glucose potentiation of arginine-induced insulin secretion, was significantly decreased in donors (maximal acute insulin response [AIRmax]: donors = 666 +/- 84 pM vs controls = 1,772 +/- 234 pM) while the PG50 (the glucose value at which the half-maximal response was observed) was the same in the two groups. Donors and controls responded to 60-min continuous intravenous infusions of glucose by reaching identical serum glucose values, despite significantly lower insulin secretory responses in donors. We conclude that hemipancreatectomy in human donors is associated with decreased pancreatic alpha and beta cell function. Since donors generally maintain normoglycemia after hemipancreatectomy despite diminished insulin secretion, our data suggest that healthy humans may compensate for hemipancreatectomy by increasing glucose disposal.


Assuntos
Ilhotas Pancreáticas/fisiologia , Doadores de Tecidos , Adulto , Análise de Variância , Arginina/administração & dosagem , Glicemia/metabolismo , Feminino , Glucagon/administração & dosagem , Glucagon/sangue , Glucose/administração & dosagem , Teste de Tolerância a Glucose , Humanos , Insulina/sangue , Insulina/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/cirurgia , Cinética , Masculino , Pessoa de Meia-Idade
7.
J Clin Invest ; 97(2): 455-60, 1996 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-8567967

RESUMO

The cause of disproportionate hyperproinsulinemia in patients with type II diabetes is controversial. To examine whether increased beta cell demand might contribute, we measured proinsulin and insulin concentrations in clinically healthy humans who had undergone hemipancreatectomy for the purpose of organ donation, a procedure previously demonstrated to increase beta cell demand and diminish insulin secretory reserve capacity. Subjects were studied at least 1 yr after hemipancreatectomy. Seven donors were followed prospectively and serves as their own controls. Nine additional donors were matched with normal controls (cross-sectional group). Fasting serum concentrations of intact proinsulin and conversion intermediates (total) were measured by a two-step radioimmunoassay; independent determinations of intact proinsulin and 32,33 split proinsulin were performed using an immunoradiometric assay. Serum total proinsulin values were significantly greater in hemipancreatectomized groups than controls (prospective group: predonation = 6.24 +/- 1.14 pM, postdonation = 34.63 +/- 17.47 pM, P < 0.005; cross-sectional group: controls = 5.78 +/- 1.12 pM, donors = 15.22 +/- 5.20 pM, P < 0.025). The ratio of total proinsulin to immunoreactive insulin was directly correlated with fasting plasma glucose and showed a significant inverse relationship to secretory reserve capacity. Both absolute and relative hyperproinsulinemia is found in hemipancreatectomized donors. These data demonstrate that partial pancreatectomy with its associated increase in beta cell demand raises measures of proinsulin in humans.


Assuntos
Ilhotas Pancreáticas/metabolismo , Proinsulina/sangue , Adulto , Glicemia/metabolismo , Jejum , Feminino , Humanos , Imunoensaio , Insulina/sangue , Masculino , Transplante de Pâncreas , Pancreatectomia , Doadores de Tecidos
8.
Minerva Endocrinol ; 31(2): 149-58, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16682938

RESUMO

The brain uses glucose as a primary fuel for energy generation. Glucose gains entry into the brain by facilitated diffusion across the blood-brain barrier. Glucose transport may adapt during changes in cerebral glucose metabolism, neural activation and changes in plasma glucose levels. Within the brain, glucose is either oxidized to produce ATP or used to synthesize glycogen. To ensure the delivery of a continuous supply of glucose to maintain normal cellular function, the brain has developed a complex regulatory system to preserve its supply. Gluco-sensing neurons have been demonstrated in various regions of the brain and they appear to play an important role in not only detecting changes in brain glucose levels but also in initiating responses to maintain constant brain glucose levels. In this review, we will discuss the regulation of brain glucose metabolism (CMR(gluc)) and how it adapts to chronic changes in glycemia, like that seen in hyperglycemic patients with diabetes mellitus or patients with type 1 diabetes, recurrent hypoglycemia, and hypoglycemia unawareness. We will also consider the role of brain glycogen in providing fuel for energy under conditions of stress.


Assuntos
Barreira Hematoencefálica/metabolismo , Encéfalo/metabolismo , Glucose/metabolismo , Encéfalo/irrigação sanguínea , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Transportador de Glucose Tipo 1/metabolismo , Transportador de Glucose Tipo 3/metabolismo , Glicogênio/metabolismo , Humanos , Insulina/metabolismo , Neuroglia/metabolismo , Neurônios/metabolismo
9.
Diabetes ; 43(5): 661-6, 1994 May.
Artigo em Inglês | MEDLINE | ID: mdl-8168643

RESUMO

Although successful pancreas transplantation in humans with type I diabetes mellitus restores glucose-induced insulin secretion, provides freedom from insulin treatment, and normalizes fasting glucose levels, much less is known about its effects on counterregulation of hypoglycemia. To determine whether pancreas transplantation normalizes glucagon secretion and hepatic glucose production (HGP) during hypoglycemia, we performed hyperinsulinemic hypoglycemic clamps in successful recipients of pancreas allografts. Recipients were found to have glucagon secretory responses during hypoglycemia that were similar to those of control subjects (incremental glucagon response: recipients, 147 +/- 34 ng/L; control subjects, 161 +/- 43 ng/L, NS) but were significantly higher than those of matched subjects with type I diabetes (23 +/- 9 ng/L, P < 0.01). HGP rates at the end of 120 min of hypoglycemia were also significantly higher in recipients and control subjects than in subjects with diabetes (pancreas recipients, 1.92 +/- 0.33 mg.kg-1.min-1; control subjects, 2.05 +/- 0.18 mg.kg-1.min-1; subjects with type I diabetes, 0.58 +/- 0.12 mg.kg-1.min-1). A comparison with a third group of nondiabetic kidney transplant recipients demonstrated that the beneficial effects on glucose counterregulation were a result of pancreas transplantation and not the associated immunosuppressive therapy. We conclude that pancreas transplantation restores hypoglycemia-induced glucagon secretion and HGP, thereby allowing for normalization of glucose recovery from hypoglycemia.


Assuntos
Glicemia/metabolismo , Diabetes Mellitus Tipo 1/tratamento farmacológico , Diabetes Mellitus Tipo 1/metabolismo , Gluconeogênese , Fígado/metabolismo , Transplante de Pâncreas/fisiologia , Adulto , Peptídeo C/sangue , Peptídeo C/metabolismo , Diabetes Mellitus Tipo 1/sangue , Feminino , Glucagon/sangue , Glucagon/metabolismo , Glucose/metabolismo , Técnica Clamp de Glucose , Humanos , Hipoglicemia/metabolismo , Imunossupressores/uso terapêutico , Infusões Intravenosas , Insulina/administração & dosagem , Insulina/sangue , Insulina/farmacologia , Transplante de Rim/fisiologia , Masculino , Transplante de Pâncreas/imunologia , Valores de Referência
10.
Diabetes ; 44(1): 85-9, 1995 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-7813819

RESUMO

Previously, we have demonstrated that somatostatin mediates all of its inhibitory effects on glucose-induced insulin secretion from the HIT-T15 cell through pertussis toxin-sensitive G-proteins and that the membrane fraction of this clonal line of pancreatic beta-cells contains six such proteins: G(i) alpha 1, G(i) alpha 2, G(i) alpha 3, and three forms of G(o) alpha. To determine the specificity of somatostatin receptor-G-protein coupling in HIT-T15 cells, we examined the ability of antisera specific for the COOH-terminus of G alpha subtypes to inhibit somatostatin-induced augmentation of membrane GTPase activity. GTPase activity increased in membranes as a function of GTP. At all concentrations of GTP studied, 1 mumol/l somatostatin stimulated GTPase activity. Pertussis-toxin pretreatment prevented the effects of somatostatin. Antisera selective for G(o) alpha subtypes reduced the effects of somatostatin on GTPase activity (GTPase activity in absence of antisera, 125 +/- 3% of control; in the presence of antisera 976, 110 +/- 2% of control; n = 13, P < 0.001), whereas antisera directed against G(i) alpha 1, G(i) alpha 2, G(i) alpha 3, and Gs alpha were without effect. Somatostatin also significantly prevented cyclic AMP accumulation during perifusion with 11.1 mmol/l glucose through a pertussis toxin-sensitive mechanism. These data indicate that the somatostatin receptor couples to G(o) alpha in the HIT-T15 cell and suggest that G(o) alpha may link somatostatin to cyclic AMP metabolism in pancreatic beta-cells.


Assuntos
Proteínas de Ligação ao GTP/metabolismo , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/metabolismo , Somatostatina/farmacologia , Animais , Linhagem Celular , Membrana Celular/química , Membrana Celular/metabolismo , Membrana Celular/ultraestrutura , Cricetinae , AMP Cíclico/metabolismo , GTP Fosfo-Hidrolases/fisiologia , Glucose/farmacologia , Guanosina Trifosfato/fisiologia , Insulina/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/química , Mesocricetus , Toxina Pertussis , Receptores de Somatostatina/análise , Receptores de Somatostatina/metabolismo , Fatores de Virulência de Bordetella/farmacologia
11.
Diabetes ; 40(1): 1-6, 1991 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-1901807

RESUMO

Guanine nucleotide-binding proteins (G proteins) are critically important mediators of many signal-transduction systems. Several important sites regulating stimulus-secretion coupling and release of insulin from pancreatic beta-cells are modulated by G proteins. Gs mediates increases in intracellular cAMP associated with hormone-induced stimulation of insulin secretin. Gi mediates decreases in intracellular cAMP caused by inhibitors of insulin secretion, e.g., epinephrine, somatostatin, prostaglandin E2, and galanin. G proteins also regulate ion channels, phospholipases, and distal sites in exocytosis. Cholera and pertussis toxins irreversibly ADP ribosylate G proteins and are important tools that can be used both to manipulate G-protein-dependent modulators of insulin secretion and detect and quantify G proteins by electrophoretic techniques. The stage is set to pursue these initial observations in greater depth and ascertain whether G-protein research will provide important new insights into normal and abnormal regulation of insulin secretion.


Assuntos
Proteínas de Ligação ao GTP/fisiologia , Insulina/metabolismo , Transdução de Sinais , Animais , Secreção de Insulina , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/fisiologia , Modelos Biológicos
12.
Diabetes ; 38(11): 1439-45, 1989 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-2482818

RESUMO

Although prostaglandin E2 (PGE2) is known to inhibit glucose-induced insulin secretion, it is uncertain whether PGE2 actions on the beta-cell are direct, whether they are equipotent for both phases of hormone secretion, and whether the same mechanism of action prevails throughout. Study of the HIT cell, a clonal line of pancreatic beta-cells, provides answers to these questions because perifusion with glucose and 3-isobutyl-1-methylxanthine stimulates biphasic insulin secretion. Perifusion with PGE2 decreased both the first and second phases of glucose-induced insulin release to 47 +/- 4% of controls. Pretreatment with pertussis toxin partly prevented PGE2 inhibition to 80 +/- 4% of controls for first phase and 79 +/- 4% of controls for second phase. To evaluate whether the partial prevention of PGE2 inhibition seen with pertussis toxin pretreatment was caused by Gi heterotrimer association between the preincubation period and the end of perifusion, PGE2 actions were also examined during continuous treatment with pertussis toxin. Under these conditions, PGE2 inhibition of both phases was totally prevented. However, no difference was observed in membrane protein ADP ribosylation when cells were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after pretreatment or continuous treatment with pertussis toxin. Cyclic AMP (cAMP) accumulation was inhibited by PGE2 (from 3263 +/- 153 to 1549 +/- 158 fmol/10(6) cells) but less so after pretreatment with pertussis toxin (correlation between insulin release and cAMP accumulation during perifusion; n = 18, r = .85, P less than .001). Thus, PGE2 equally inhibits both phases of glucose-induced insulin secretion and cAMP generation through a pertussis toxin-sensitive G protein-mediated direct effect on the pancreatic beta-cell.


Assuntos
AMP Cíclico/metabolismo , Dinoprostona/farmacologia , Proteínas de Ligação ao GTP/fisiologia , Glucose/farmacologia , Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Toxina Pertussis , Fatores de Virulência de Bordetella/farmacologia , 1-Metil-3-Isobutilxantina/farmacologia , Animais , Linhagem Celular , Células Cultivadas , Células Clonais , Cricetinae , Secreção de Insulina , Ilhotas Pancreáticas/efeitos dos fármacos
13.
Diabetes ; 50(10): 2203-9, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11574399

RESUMO

The continuous delivery of glucose to the brain is critically important to the maintenance of normal metabolic function. However, elucidation of the hormonal regulation of in vivo cerebral glucose metabolism in humans has been limited by the lack of direct, noninvasive methods with which to measure brain glucose. In this study, we sought to directly examine the effect of insulin on glucose concentrations and rates of glucose transport/metabolism in human brain using (1)H-magnetic resonance spectroscopy at 4 Tesla. Seven subjects participated in paired hyperglycemic (16.3 +/- 0.3 mmol/l) clamp studies performed with and without insulin. Brain glucose remained constant throughout (5.3 +/- 0.3 micromol/g wet wt when serum insulin = 16 +/- 7 pmol/l vs. 5.5 +/- 0.3 micromol/g wet wt when serum insulin = 668 +/- 81 pmol/l, P = NS). Glucose concentrations in gray matter-rich occipital cortex and white matter-rich periventricular tissue were then simultaneously measured in clamps, where plasma glucose ranged from 4.4 to 24.5 mmol/l and insulin was infused at 0.5 mU. kg(-1). min(-1). The relationship between plasma and brain glucose was linear in both regions. Reversible Michaelis-Menten kinetics fit these data best, and no differences were found in the kinetic constants calculated for each region. These data support the hypothesis that the majority of cerebral glucose uptake/metabolism is an insulin-independent process in humans.


Assuntos
Encéfalo/metabolismo , Glucose/metabolismo , Hipoglicemiantes/farmacologia , Insulina/farmacologia , Adulto , Transporte Biológico , Encéfalo/efeitos dos fármacos , Ventrículos Cerebrais/metabolismo , Feminino , Técnica Clamp de Glucose , Humanos , Hipoglicemiantes/sangue , Insulina/sangue , Cinética , Espectroscopia de Ressonância Magnética , Masculino , Lobo Occipital/metabolismo , Concentração Osmolar , Valores de Referência
14.
Diabetes ; 43(4): 593-8, 1994 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-8138066

RESUMO

Although both kidney and pancreas transplantation can restore renal and pancreatic endocrine functions, the accompanying immunosuppression may cause diminished glucose tolerance in some individuals. Therefore, we determined to what extent pancreas transplantation itself and the triple immunosuppressive therapy used in pancreas transplant recipients have adverse effects on insulin secretory reserve. Beta-cell secretory reserve was assessed by the method of glucose potentiation of arginine-induced insulin secretion in 25 normoglycemic pancreas recipients, 12 nondiabetic kidney recipients using the same immunosuppressive therapy, 3 psoriasis patients treated long term with cyclosporine, 5 arthritis patients treated long term with prednisone, and their respective sex-, age-, and body mass index-matched control subjects. Levels of fasting glucose, HbA1c, and glucose disappearance rates were normal in all subjects. During the glucose potentiation study, pancreas recipients had significantly less insulin secretion than control subjects (maximal acute response [ARmax] = 1,083 +/- 93% vs. 3,938 +/- 355%, P < 0.001). Insulin responses were also decreased in kidney recipients (ARmax = 2,296 +/- 290%) vs. control subjects (4,691 +/- 554%, P = 0.001) and in psoriasis patients treated with cyclosporine (ARmax = 2,153 +/- 390%) vs. control subjects (3,962 +/- 88%, P = 0.011), but not as extreme as that seen in pancreas recipients. No abnormalities were observed in arthritis patients treated with steroids. We conclude that normoglycemic pancreas and kidney transplant recipients receiving triple immunosuppressive therapy have diminished beta-cell secretory reserve. Because this defect was present in psoriasis patients treated long term with cyclosporine, but not in arthritis patients treated long term with prednisone, this adverse effect was probably caused in part by cyclosporine.


Assuntos
Diabetes Mellitus Tipo 1/cirurgia , Imunossupressores/uso terapêutico , Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Transplante de Rim/fisiologia , Transplante de Pâncreas/fisiologia , Adulto , Arginina , Artrite/sangue , Artrite/tratamento farmacológico , Glicemia/metabolismo , Peptídeo C/sangue , Peptídeo C/metabolismo , Ciclosporina/uso terapêutico , Diabetes Mellitus Tipo 1/sangue , Feminino , Glucose/farmacologia , Humanos , Secreção de Insulina , Ilhotas Pancreáticas/efeitos dos fármacos , Masculino , Prednisona/uso terapêutico , Psoríase/sangue , Psoríase/tratamento farmacológico , Transplante Homólogo
15.
Diabetes ; 41(11): 1390-9, 1992 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-1383067

RESUMO

G-proteins are important mediators of hormonal inhibition of insulin secretion. To characterize the pertussis toxin-sensitive substrates present in HIT cell membranes, we performed immunoblots with specific antisera and found evidence for the presence of Gi alpha 1, Gi alpha 2, Gi alpha 3, and three forms of Go alpha. We observed that pertussis toxin-sensitive substrates mediate all of the effects of SRIF, and a major portion of the effects of EPI, on insulin secretion from rat islets during static incubations. These results agree with our previously reported studies examining phasic glucose-induced insulin secretion from HIT cells. To ascertain whether inhibition of adenylate cyclase, presumably involving coupling of the catalytic subunit to Gi, may be a common mechanism for both hormones, we studied the effects of 8-bromo-cyclic AMP and found that this agent partially prevented the inhibitory effects of both hormones. We also observed that the inhibitory effects of SRIF and EPI on insulin were nonadditive, that both hormones were additive to nickel chloride during inhibition of insulin release, and that they noncompetitively inhibited glipizide-induced insulin secretion through pertussis toxin-sensitive mechanisms. Together, these results suggest that both hormones exert their effects on insulin secretion at multiple G-protein-regulated sites including adenylate cyclase and sites distal to the glipizide-binding site on the KATP channel.


Assuntos
Toxina Adenilato Ciclase , Epinefrina/farmacologia , Proteínas de Ligação ao GTP/metabolismo , Glucose/farmacologia , Ilhotas Pancreáticas/metabolismo , Toxina Pertussis , Somatostatina/farmacologia , Fatores de Virulência de Bordetella/farmacologia , 1-Metil-3-Isobutilxantina/farmacologia , 8-Bromo Monofosfato de Adenosina Cíclica/farmacologia , Adenosina Difosfato Ribose/metabolismo , Animais , Linhagem Celular , Cricetinae , Proteínas de Ligação ao GTP/isolamento & purificação , Glipizida/farmacologia , Técnicas In Vitro , Ilhotas Pancreáticas/efeitos dos fármacos , Cinética , Mesocricetus , Modelos Biológicos , NAD/metabolismo , Ratos , Ratos Sprague-Dawley
16.
Diabetes ; 43(8): 1020-6, 1994 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-8039595

RESUMO

Cystic fibrosis (CF) patients demonstrate a spectrum of pancreatic beta-cell abnormalities. Those with no exocrine insufficiency (NEXO) have normal insulin secretion. Exocrine-insufficient CF patients with overt diabetes (EXO-IT) have impaired insulin secretion and fasting hyperglycemia. Exocrine-insufficient patients without diabetes (EXO) have impaired insulin secretion but maintain normoglycemia. We postulated that EXO individuals compensate for insulin deficiency by increasing insulin sensitivity and investigated glucose utilization in CF. To examine hepatic and peripheral insulin sensitivity, euglycemic-hyperinsulinemic clamp studies were performed by using the hot GINF isotope dilution technique. Insulin was sequentially infused at 0.25, 1.0, and 10.0 mU.kg-1.min-1. Glucose-mediated glucose uptake (GMGU) was assessed on another day with hyperglycemic clamp studies, during which insulin and somatostatin were infused to hold insulin-mediated glucose uptake constant between the two clamp studies. Skeletal muscle GLUT4 levels were assessed in EXO and control patients with Western blotting. Three patterns of peripheral and hepatic insulin sensitivity were seen that were related to the degree of pancreatic beta-cell dysfunction. NEXO individuals had normal peripheral and hepatic insulin sensitivity. EXO individuals had enhanced peripheral insulin sensitivity that was not associated with a change in skeletal muscle glucose transporter abundance compared with control patients; paradoxically, EXO subjects demonstrated hepatic insulin resistance. EXO-IT had peripheral and hepatic insulin resistance. GMGU was diminished in both EXO and EXO-IT subjects. The unique combination of increased hepatic glucose production and increased peripheral glucose utilization seen in EXO may be a metabolic adaptation to increased peripheral energy needs.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Fibrose Cística/fisiopatologia , Insulina/farmacologia , Proteínas Musculares , Adulto , Glicemia/metabolismo , Western Blotting , Feminino , Glucose/metabolismo , Técnica Clamp de Glucose , Transportador de Glucose Tipo 4 , Glicogênio/metabolismo , Humanos , Insulina/administração & dosagem , Insulina/sangue , Resistência à Insulina , Ilhotas Pancreáticas/fisiopatologia , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Proteínas de Transporte de Monossacarídeos/metabolismo , Músculos/efeitos dos fármacos , Músculos/metabolismo
17.
Diabetes Care ; 12(8): 544-52, 1989 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-2673694

RESUMO

Ten untreated type II (non-insulin-dependent) diabetic subjects were given 15, 25, 35, and 50 g glucose orally. Plasma glucose, insulin, C-peptide, glucagon, urea nitrogen, alpha-amino acid nitrogen, and lactate concentrations were measured, and net 5-h postprandial areas were calculated. The net glucose-area response to the ingested glucose dose (with the 0-time value as a constant baseline) was best described by a second-order polynomial equation, whereas insulin-area response was best described by a third-order equation. In a separate study, 5 untreated type II diabetic subjects were given only water, and the same metabolites and hormones were measured. Data from this study indicated that the baseline was not constant during the 5 h of study but decreased progressively. The net glucose-area and insulin-area responses to ingested glucose dose (with the decreasing baseline) were then best described by third-order equations. Glucagon, alpha-amino acid nitrogen, and lactate concentrations were exquisitely sensitive to a rise in glucose and insulin concentrations. These were all decreased with the lowest concentration of glucose used. At this dose of glucose, the increase in insulin was only 15 microU/ml.


Assuntos
Glicemia/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Glucose/farmacologia , Hormônios Pancreáticos/metabolismo , Idoso , Aminoácidos/análise , Nitrogênio da Ureia Sanguínea , Peptídeo C/sangue , Relação Dose-Resposta a Droga , Alimentos , Glucagon/sangue , Humanos , Insulina/sangue , Lactatos/sangue , Masculino , Pessoa de Meia-Idade , Nitrogênio/análise
18.
Metabolism ; 46(11): 1364-6, 1997 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9361700

RESUMO

To determine whether arterialized venous blood obtained from a foot vein could be substituted for arterialized venous blood obtained from a hand vein during studies using the glucose clamp technique, we simultaneously measured glucose concentrations and PO2 in blood samples obtained from the heated hands and feet of five normal volunteers during the euglycemic and hyperglycemic steps of a hyperinsulinemic clamp. Plasma glucose concentrations were found to be virtually identical in arterialized venous blood drawn from the hand and the foot under both euglycemic and hyperglycemic conditions. The correlation between these values was significant (R2 = .99, P < .001). PO2 measurements in blood drawn from the heated hand or foot were not statistically different. We conclude that the glucose concentration measured in arterialized venous blood drawn from the foot is equivalent to the concentration in arterialized venous blood drawn from the hand. These observations will allow investigators to study in vivo glucose metabolism in individuals with poor venous access in the upper extremities and to use protocols that make the arms of the subject inaccessible for blood sampling during the study.


Assuntos
Glicemia/análise , Pé/irrigação sanguínea , Mãos/irrigação sanguínea , Adulto , Metabolismo Basal/fisiologia , Feminino , Técnica Clamp de Glucose , Humanos , Hiperglicemia/sangue , Hiperglicemia/patologia , Masculino
19.
Postgrad Med ; 103(1): 61-3, 66-8, 1998 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9448674

RESUMO

The microvascular complications of diabetes mellitus are responsible for a substantial portion of associated morbidity and mortality. Fortunately, recent evidence indicates that improved glycemic and blood pressure control can slow and perhaps even stop the development of retinopathy, nephropathy, and neuropathy in diabetic patients. In addition, early recognition of these complications provides the opportunity for early treatment, which has been shown to preserve vision, renal function, and limb integrity. Screening for the early.


Assuntos
Complicações do Diabetes , Nefropatias Diabéticas , Neuropatias Diabéticas , Retinopatia Diabética , Humanos
20.
Minn Med ; 84(3): 58-61, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11269842

RESUMO

CONTEXT: Continuing medical education (CME) is necessary for ongoing licensure and is critical in maintaining professional expertise. However, educators may not always consider their students preferences when developing new programs. OBJECTIVE: To determine physician preference for the format of CME programs and to learn what factors contribute to selecting a CME activity. DESIGN: Survey with 12 multiple response items pertaining to educational objectives, past educational experiences, and demographic information. PARTICIPANTS: A total of 1,967 Minnesota physicians were sent the survey; 385 physicians returned surveys within 2 months of mailing date (20% return rate). RESULTS: The vast majority of respondents reported participating in traditional CME programs during the preceding two years, and most said they planned to attend a traditional program in the next two years. CONCLUSIONS: Minnesota physicians overwhelmingly prefer attending traditional CME programs to participating in more interactive, technology-based activities. Before new technology such as the Internet can be widely used in CME, it must be made attractive to the practicing physician.


Assuntos
Atitude do Pessoal de Saúde , Educação Médica Continuada , Medicina de Família e Comunidade , Medicina Interna/educação , Currículo , Coleta de Dados , Humanos , Minnesota
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