Synthesis of soluble proinsulin in a cell-free protein synthesis system / 生物工程学报

Proinsulin (Pins) is the precursor of insulin. The expression of proinsulin in Escherichia coli forms inclusion body, so that the recombinant protein should be processed with multiple steps to form active insulin. With the development in biotechnology, cell-free protein synthesis (CFPS) system is becoming a valuable tool in protein expression by decoupling the cell growth with protein production, which allows it to express proteins that would interfere with cell physiology. In this study, we synthesized soluble proinsulin in CFPS system in order to establish a new approach for both insulin expression and delivery. The soluble proinsulin was successfully expressed in CFPS system by fusing proinsulin with two types of fluorescent protein. The expression of Pins-mCherry was confirmed by Western blotting analysis, and the Pins-eGFP titer was (12.28±3.45) μg/mL in CFPS system. These results implicated that the proinsulin was expressed partially in soluble form. Here, for the first time, we successfully expressed soluble proinsulin in CFPS system by fluorescent protein fusion. These results provide useful information in developing new insulin expression and delivery method.

Mesenchymal Stem Cell Differentiation into Adipocytes Is Equally Induced by Insulin and Proinsulin In Vitro

BACKGROUND AND OBJECTIVES: In advanced β-cell dysfunction, proinsulin is increasingly replacing insulin as major component of the secretion product. It has been speculated that proinsulin has at least the same adipogenic potency than insulin, leading to an increased tendency of lipid tissue formation in patients with late stage β-cell dysfunction. METHODS AND RESULTS: Mesenchymal stem cells obtained from liposuction material were grown in differentiation media containing insulin (0.01 μmol), proinsulin (0.01 μmol) or insulin+proinsulin (each 0.005 μmol). Cell culture supernatants were taken from these experiments and an untreated control at weeks 1, 2, and 3, and were stored at −80°C until analysis. Cell differentiation was microscopically supervised and adiponectin concentrations were measured as marker for differentiation into mature lipid cells. This experiment was repeated three times. No growth of lipid cells and no change in adiponectin values was observed in the negative control group (after 7/14/12 days: 3.2±0.5/3.3±0.1/4.4±0.5 ng/ml/12 h). A continuous differentiation into mature adipocytes (also confirmed by Red-Oil-staining) and a corresponding increase in adiponectin values was observed in the experiments with insulin (3.6±1.9/5.1±1.4/13.3±1.5 ng/ml/12 h; p < 0.05 week 1 vs. week 3) and proinsulin (3.3±1.2/3.5±0.3/12.2±1.2 ng/ml/12 h; p < 0.05). Comparable effects were seen with the insulin/proinsulin combination. CONCLUSIONS: Proinsulin has the same adipogenic potential than insulin in vitro. Proinsulin has only 10~20% of the glucose-lowering effect of insulin. It can be speculated that the adipogenic potential of proinsulin may be a large contributor to the increased body weight problems in patients with type 2 diabetes and advanced β-cell dysfunction.

Implication of proinsulin to insulin ratio in the basic and clinical research of diabetes / 中华内分泌代谢杂志

Proinsulin is the precursor of mature insulin.Proinsulin to insulin ratio reflects the degree of pancreatic β-cell dysfunction and the progression of type 2 diabetes, and may predict the risk of diabetes development.Some variants in susceptibility genes of diabetes are associated with the elevation of proinsulin to insulin ratio.Moreover, several antidiabetic drugs are able to decrease the proinsulin to insulin ratio in patients with type 2 diabetes.Therefore, the proinsulin to insulin ratio may act as a simple and useful indicator in the etiological study, risk prediction, disease progression and therapeutical evaluation in type 2 diabetes.

Transgenic Expression and Identification of Recombinant Human Proinsulin in Peanut

The increased incidence of diabetes, coupled with the introduction of alternative insulin delivery methods that rely on higher doses, is expected to result in a substantial escalation in the future demand for affordable insulin. Plant-based systems offer a safe and economical method for producing pharmaceutical proteins. We used peanut (Arachis hypogaea L.) as bio-reactors to express biosafe, stable proinsulin. We designed two proinsulin analogues (FAIA and LAIA) with substitutions in their amino acid sequences. The fast-acting insulin analogue (FAIA) contains a Gly inserted between Cys19 and Gly20, as well as a Pro28Asp substitution, in the B chain. The long-acting insulin analogue (LAIA) contains a Gly inserted between Cys19 and Gly20 and two Arg residues inserted into the terminus of the B chain, as well as an Asn21Gly substitution in the A chain. Four plasmids were constructed: pROKII-Flag-FAIA, pROKII-Flag-LAIA, pCAMBIA2301-Oleosin-FAIA and pCAMBIA2301-Oleosin-LAIA. These plasmids were transferred into peanut to produce recombinant proinsulin. Western blot and GUS staining analysis indicated that some transgenic peanut successfully expressed exogenous proinsulin. Peanut seeds can act as insulin storage sites, which is the foundation for further production of recombinant proinsulin from peanut seeds.

Analysis on detection results of blood lipid and proinsulin related indicators in patients with type 2 diabetes / 国际检验医学杂志

Objective To analyze the detection results of blood fat and proinsulin related indicators in the patients with type 2 diabetes mellitus(T2DM ) and to investigate the means for improving the patients′ clinical indicators .Methods 57 patients with T2DM in our hospital from February 2013 to February 2015 were divided into the research group ( ≥ 15 .6 mIU /L ,29 cases) and the control group (< 15 .6 mIU /L ,28 cases) according to the proinsulin level .All the cases took glucose ,at the same time the cor‐relation between the blood fat indexes with serum true insulin ,proinsulin and insulin resistance index of steady state insulin assess‐ment model was analyzed .Results Proinsulin ,serum true insulin ,2 h postprandial proinsulin ,2 h postprandial serum true insulin , insulin resistance index of steady state insulin assessment model all had correlation with and apolipoprotein B /apolipoprotein A1 . Conclusion The proinsulin level in the patients with T 2DM is increased ,thus the ratio of apolipoprotein B/apolipoprotein A1 will be accordingly increased .

Serum Proinsulin in Bangladeshi Subjects with Impaired Glucose Tolerance.

Hyperproinsulinemia is commonly present in subjects with impaired glucose tolerance. The present study was undertaken to investigate the proinsulin level in Bangladeshi IGT subjects and to explore its association with insulin resistance. This observational study was conducted under a case-control design with IGT subjects (n=50) and controls (n=44). IGT was diagnosed following the WHO Study Group Criteria. Serum glucose was measured by glucose-oxidase method, serum lipid profile by enzymatic method and serum insulin and serum proinsulin were measured by ELISA method. Insulin secretory capacity (HOMA%B) and insulin sensitivity (HOMA%S) were calculated from fasting serum glucose and fasting serum insulin by homeostasis model assessment. The study subjects were age- and BMI- matched. Mean (±SD) age (yrs) of the control and IGT subjects were 40±6 and 40±5 respectively (p=0.853). Mean (±SD) BMI of the control and IGT subjects were 23±3 and 22±2 respectively (p=0.123). Fasting glucose was not significantly higher in IGT subjects, but serum glucose 2 hours after 75 gm glucose load was significantly higher in IGT subjects. Median (Range) value of fasting serum glucose (mmol/l) of control and IGT subjects were 5.3 (3.8-6) and 5.2 (4-12) respectively; (p=0.297). Median (Range) value of serum glucose (mmol/l) 2 hours after 75 gm glucose load of control and IGT subjects were 6.1 (3-7.8) and 7.9 (5- 21) respectively; (p=0.001). Fasting TG was significantly higher in IGT subjects and LDL-c was significantly lower in IGT subjects. Serum Total cholesterol and HDL-c were not significantly different between the IGT and control subjects. Median (Range) value of fasting serum TG (mg/dl) of control and IGT subjects were 119 (51-474) and 178 (82-540) respectively; (p=0.001). Median (Range) value of fasting serum T chol (mg/dl) of control and IGT subjects were 180 (65-272) and 186 (140-400) respectively; (p=0.191). Median (Range) value of fasting serum HDL-C (mg/dl) of control and IGT subjects were 29 (19-45) and 31 (15-78) respectively; (p=0.914). Median (Range) value of fasting serum LDL-C (mg/dl) of control and IGT subjects were 117(29-201) and 111(41- 320) respectively; (p=0.001). Fasting serum proinsulin was significantly higher in IGT subjects. Median (Range) value of fasting serum proinsulin (pmol/l) of control and IGT subjects were 9.2(1.8-156) and 17(3-51) respectively; (p=0.001). Insulin secretory capacity (HOMA%B) was higher but insulin sensitivity (HOMA%S) was significantly lower in case of IGT subjects. Median (Range) value of HOMA%B of control and IGT subjects were 97(46-498) and 164(17-300) respectively; (p=0.001). Median (Range) value of HOMA%S of control and IGT subjects were 68(19-270) and 39(15-110) respectively (p=0.001). In multiple regression analysis a significant negative association was found between fasting proinsulin and insulin sensitivity (p=0.037). The data led to the following conclusions: a) Insulin resistance is the predominant defect in Bangladeshi IGT subjects. b) Basal proinsulin level is significantly increased in IGT subjects. c) Insulin resistance is negatively associated with serum proinsulin in IGT subjects.

The Short Term Effect of Insulin on Proinsulin Gene Expression of HIT-T15 Insulinnoma Cells / 天津医药

Objective To investigate the short term effect of insulin on proinsulin gene expression of HIT-T15 insu-linnoma cells(pancreatic isletβ-cell). Methods The HIT-T15 cells were randomly divided into four groups.Blank Con-trol Group (LG):complete medium contain 1.4 mmol/L glucose. Control group (LGC):co-cultured nifedipine with medium in order to restain endogenous insulin release. Experimental group (LINS or HINS) add 0.5 U/L insulin or 5 U/L insulin on top of LGC. After being stimulated for 0, 30, 60, 90, 120 mins, proinsulin (PI) mRNA level were assessed by semi-quantitative RT-PCR. Insulin receptor substrate1 (IRS1) tyrosine phosphorylation was detected by immunocytochemistry. Results (1) Expression of PI was up regulated by both LINS and HINS, and peak at 60 mins. (2) After stimulation for 30 mins, the level of IRS1 tyrosine phosphorylation in the experimental group was significantly higher than control group, and the peak time be-tween LINS and HINS was different. (3) Between group of LG and LGC, the expression of PI mRNA and IRS1 tyrosine phos-phorylation show no difference. Conclusion Short term exogenous insulin stimulation can promote expression of proinsulin genes,which is concentration dependent. The expression and regulation of PI were related with IRS1 signal transduction.

Study of Mechanism of Proinsulin Gene Mutations in Diabetes Mellitus / 天津医药

Objective To construct several human proinsulin mutants plasmid related to diabetes and to express in INS-1 (Insulin secreting beta cell derived line) cell. Methods Human mild proinsulin gene was used as template , and site-directed mutagenesis PCR was employed to generate four human proinsulin plasmid mutants. Each mutant plasmid was sequenced then transfected with empty plasmid and mild plasmid into INS-1 cell by liposome 2000. Insulin value in each cell solution was determined by radioimmunoassay. Results Proinsulin mutants plasmid were confirmed by sequencing. In-sulin values in culture solution of H-C(B19)G、H-L(B11)P、H-R(S6)C mutants are less than those in wild type and H-F (B25)L(P＜0.05). Comparison of insulin values between H-C(B19)G、H-L(B11)P、H-R(S6)C groups were not statistically significant(P>0.05), and all these three groups showed no significant differences with empty plasmid group statistically (P>0.05).Insulin value of H-F(B25)L was of no significant differences statistically with empty plasmid(P>0.05). Conclu-sion Four human proinsulin mutants plasmid were constructed and expressed successfully in INS-1 cell, and different mu-tants plasmid result in diabetes through different mechanism.

Maternal glucose-insulin metabolism on early pancreatic islet function in premature infant / 临床儿科杂志

Objectives To analyze the impact of glucose-insulin metabolism during pregnancy onβ-cell function in premature infant, and to explore biomarkers for monitoringβ-cell function in preterm infant. Methods Eighty-two premature infants admitted to NICU from March to December 2012 were divided into 2 groups, a group with abnormal maternal glucose metabolism during pregnancy (35 cases) and another group with normal maternal glucose metabolism during pregnancy group (47 cases). Fasting blood glucose, insulin, C-peptide and proinsulin at 1 hour after birth and 7 days postpartum were measured respectively, and relevant indices ofβ-cell function were compared in premature infants. Results Maternal pre-pregnancy and prenatal body mass index, weight and head circumference of preterm infants at birth were signiifcantly different between two groups (P0.05). The differences in levels of proinsulin at birth, C-peptide and proinsulin at postnatal day 7 were signiifcantly different between the two groups (P0.05). Conclusions Abnormal maternal glucose metabolism in pregnancy has no effect on early pancreatic islet function in premature infant, how-ever, proinsulin secretion has been affected.

Hypothyroidism decreases proinsulin gene expression and the attachment of its mRNA and eEF1A protein to the actin cytoskeleton of INS-1E cells

The actions of thyroid hormone (TH) on pancreatic beta cells have not been thoroughly explored, with current knowledge being limited to the modulation of insulin secretion in response to glucose, and beta cell viability by regulation of pro-mitotic and pro-apoptotic factors. Therefore, the effects of TH on proinsulin gene expression are not known. This led us to measure: a) proinsulin mRNA expression, b) proinsulin transcripts and eEF1A protein binding to the actin cytoskeleton, c) actin cytoskeleton arrangement, and d) proinsulin mRNA poly(A) tail length modulation in INS-1E cells cultured in different media containing: i) normal fetal bovine serum - FBS (control); ii) normal FBS plus 1 µM or 10 nM T3, for 12 h, and iii) FBS depleted of TH for 24 h (Tx). A decrease in proinsulin mRNA content and attachment to the cytoskeleton were observed in hypothyroid (Tx) beta cells. The amount of eEF1A protein anchored to the cytoskeleton was also reduced in hypothyroidism, and it is worth mentioning that eEF1A is essential to attach transcripts to the cytoskeleton, which might modulate their stability and rate of translation. Proinsulin poly(A) tail length and cytoskeleton arrangement remained unchanged in hypothyroidism. T3 treatment of control cells for 12 h did not induce any changes in the parameters studied. The data indicate that TH is important for proinsulin mRNA expression and translation, since its total amount and attachment to the cytoskeleton are decreased in hypothyroid beta cells, providing evidence that effects of TH on carbohydrate metabolism also include the control of proinsulin gene expression.

Expression of proinsulin and insulin in insulinoma and normal pancreas / 中华胰腺病杂志

Objective To investigate the expression of proinsulin, insulin, C-peptide in insulinoma and normal pancreas and their roles. Methods Thirty-eight cases of insulinoma and 20 cases of normal pancreas from Sep. 2006 to Dec. 2009 in our hospital were selected. Immunohistochemistry was used to determine the expression of proinsulin, insulin, C-peptide. Results Proinsulin, insulin, C-peptide was expressed in insulinoma and normal pancreas. Proinsulin, C-peptide were strongly expressed in 100%insulinoma, while they were weekly expressed in 55% ～60% normal pancreas; insulin was expressed as + + +in 79% insulinoma, while it was expressed as + + + + in 85% normal pancreas. Proinsulin, C-peptide positive cell accounted for 80% ～ 100% of 38 insulinoma, and insulin positive cell accounted for 50% ～ 70%,the proinsulin/insulin ratio ＞ 1 accounted for 78.9%; while the corresponding values were 20% ～ 80%, 60% ～90%, 10.0% in normal pancreas, and the difference was statistically significant ( P ＜ 0.05 ). Conclusions The proinsulin/insulin ratio ＞ 1 is 78.9% in insulinoma, and detection of proinsulin may help to diagnose insulinoma.

Relationship between adiponectin and the first phase of glucose-stimulated insulin secretion from pancreatic β-cell in patients with type 2 diabetes mellitus / 中华内分泌代谢杂志

Objective To investigate the relationship between adiponectin and the first-phase of pancreatic P-cell insulin secretion in subjects with different statuses of glucose tolerance. Methods Thirty-seven patients with newly diagnosed type 2 diabetes mellitus (DM) , 30 patients with abnormal glucose tolerance (IGR) , and 40 normal control subjects (NGT) underwent intravenous glucose tolerance test (IVGTT). Fasting adiponectin and proinsulin (PI) was assayed by EL1SA. Fasting free fatty acid ( FFA) was measured by colorimetry. Insulin area under the curve ( AUC ) , incremental AUC (iAUC) from 0 min to 10 min, AIR3-5, homeostasis model assessment for insnlin resistance (HOMA-IR) , and for β cell function ( HOMA-p) were calculated. The relationship between adiponectin and AUC, iAUC, AIR3-5, proinsulin, FFA, and HOMA-IR was explored. Results (1) The levels of AUC, iAUC, AIR3-5, and adiponectin in DM group and IGR group were significantly lower than those in NGT group (P<0.05), reduced in DM group than those in IGR group(P<0.05). (2) The levels of PI in DM group and IGR group were significantly higher than that in NGT (P<0.05). (3) Adiponectin was positively correlated with HOMA-p,AUC,iAUC,AIR3-5, and HDL-C,while negatively correlated with proinsulin, HOMA-IR, and LDL-C. (4) Proinsulin was positively correlated with HOMA-IR. (5 ) Multiple regression stepwise analysis showed that adiponectin was independently associated with AUC. Conclusions Adiponectin was an independent factor affecting the first phase of pancreatic p-cell insulin secretion. Low adiponectin level could predict the dysfunction of the first phase pancreatic p-cell secretion as well as insulin resistance in patients with type 2 diabetes.

Proinsulin gene therapy in diabetic rats——Comparison of the effects on blood glucose by intraportal infusion and intramuscular injection / 中华内分泌代谢杂志

Objective To compare the effects of rat proinsulin gene therapy via intraportal infusion and intramuscular injection blood glucose level in streptozotocin-induced diabetic rots. Methods (1) Recombinant eukaryotic cell expression plasmid of rat proinsulin gene pCMV/proiusulin was transferred into streptozotocin-induced diabetic rats by intraportal infusion and intramuscular injection to observe the effect of rat proiusulin gene therapy in diabetic rats. The treatment group by intraportal infusion (group A) and the group by intramuscular injection (group C) were given pCMV/proinsulin naked plasmid DNA 100 μg, while the control groups by intraportal infusion (group B) or by intramuscular injection (group D) were treated with similar amount of pCMV DNA. Normal group and diabetes mellitus group were also observed at the same time. (2) Blood glucose level was tested and serum insulin was determined by radioimmunoassay. RT-PCR and immunohistochemistry were used to detemine proinsulin mRNA and protein expressions in liver and skeletal muscle and protein. Results (1) The blood glucose levels in two treated groups were both decreased. In group A, levels of blood sugar decreased about 7 mmol/L and glycemie control was maintained for 3-4 weeks. Serum insulin levels step up significantly after pCMV/proinsulin gene therapy. The blood glucose level in group A was significantly lower than those of group B and DM group (P<0.05), while the serum insulin level was higher than those of two groups (P<0.05). In group C, blood glucose levels decreased about 4 mmol/L and glycemic control was maintained for 1-2 weeks. Meanwhile, the concentrations of insulin increased markedly after gene therapy. The blood glucose in group C was significantly lower than those of group D and DM group (P<0.05), while the serum insulin level was higher than those of two groups (P<0.05). (2) Proinsulin mRNA and protein expressions could be detected in either hepatic cell of group A or skeletal muscle cell of group C, not in group B and group D. Conclusion Proiusulin genetherapy via intraportal infusion or intramuscular injection lowers significantly blood glucose in diabetic rats, and thus offers a potential approach to treatment of diabetes.

Establishment of electrochemiluminescence immunoassay to detect proinsulin levels in human serum / 中华检验医学杂志

]. Conclusions The monoclonal-based ECLIA is a sensitive, specific, and rapid method and no radiocontamination. It can be used to detect hanum serum proinsulin in type 2 diabetes.

Serum proinsulin levels in LADA patients / 中华内分泌代谢杂志

Objective To explore the characteristics of proinsulin secretion in latent autoimmune diabetes in adults (LADA). Methods Fasting and 2 h sera in oral glucose tolerance test from 36 LADA patients, 37 type 2 diabetic patients and 43 healthy controls were collected to test glucose, proinsulin (PI) and C-peptide (CP) by radioimmune assay. Glutamie acid decarboxylase antibodies (GAD-Ab) were determined by radioligand assay.Results (1) Fasting proinsulin (FPI) and 2 h proinsulin (PPI) level in LADA patients were lower than those in type 2 diabetic patients (P<0.05), being both significantly inereasad compared with healthy controls (P<0.05 or P<0.01); The ratios of FPI/FCP and PPI/PCP (%) in LADA were beth significantly higer than those of type 2 diabetes mellitus and controls (P<0.05 or P<0.01); (2) LADA type-1 (GAD-Abe>0.3) patients showed lower PI levels(P<0.05 or P<0.01) and higher PI/CP ratio (all P<0.05) than LADA type-2 (0.05≤GAD-Ab<0.3); Meanwhile, there were no significant differences in above parameters between LADA type-2 and type 2 diabetes meUitus (P>0.05). (3) GAD-Ab index was negatively correlated with FPI and PPI in LADA group (r=-0.236 and-0.268, both P<0.05), and positively correlated with PPI/PCP (r=0.254, P=0.030).Meanwhile BMI was positively correlated with FPI, PPI and PI/CP in type 2 diabetes mellitus (all P<0.01). No factor entered the multiple regression analysis for predieting the hyperproinsulinemia and dispropriately elevated proinsulin levels in LADA patients. (4) According to the 99.5 th percentile of proinsulinemia in the healthy controls, which is defined as the cutoff point dispropriately elevated proinsulin levels, the proportion of subjects with fasting dispropriately elevated proinsulin levels (FPI/FCP) were 77.8%, 62.2% and 2.3% in LADA, type 2 diabetes meUitus and controls respectively, and PPI/PCP 83.3%, 51.4% and 2.3% respectively. Conclusion LADA patients, as well as type 2 diabetic patients, all showed hyperproinsulinemia and disproportionately elevated proiasulin levels that were one of characteristics of defective β-cell function. Moreover, disproportionately elevated nproinsulin level is more evident in LADA patients than that in type 2 diabetics and this may be related to humoral immunity.

Study on the Optimum Conditions For the Expression Of Human Recombinant Proinsulin In E.Coli - BL21(DE3) with pET - 28a(+) Vector

Introduction: There are thousands of diabetes sufferers worldwide. In addition, there is an increased trend in Vietnam due to economic development, increased population, lifespan, and changing lifestyle. Insulin is a hormone, which is a natural protein. It plays an important role in the transformation of glucose in human and animal blood. Note, while insulin has not been produced in Vietnam, the production of recombinant Proinsulin is a premise for insulin. This study is based on a successful design of pET - 28a (+) Vector with recombinant Proinsulin codified gene.\r\n', u'Objectives: To define the human proinsulin codified gene and study the optimum conditions for the expression of proinsulin. \r\n', u'Subjects and method: To discover the appropriate conditions for the expression of proinsulin, including initial cell density, cultural temperature, IPTG concentration, and expression time. The product of the expression was confirmed by Sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SOS - PAGE) and reconfirmed by Western blotting with His - Tag antibody. \r\n', u'Results: Proinsulin expression was successfully proved by SOS - PAGE and Western blotting. Four appropriate conditions for the expression were confirmed as highlighted in the Conclusion. \r\n', u'Conclusion: The appropriate conditions for expression of proinsulin: cell density was 00600 0.6 - 1.0; the cultural temperature was 300C; IPTG concentration was 0.4 mM; the length of the culture time was 20 hours. \r\n', u'

Association between proinsulin, insulin, proinsulin/insulin ratio, and insulin resistance status with the metabolic syndrome

The Metabolic Syndrome (MS) constitutes an independent risk factor of cardiovascular disease. There is evidence that proinsulin blood levels and the proinsulin/insulin ratio are associated to the MS. The purpose of this study was to compare proinsulin and insulin, insulin resistance index, and the proinsulin/insulin ratio as predictors of MS. This is a cross-sectional study involving 440 men and 556 women with a mean age of 24 years. Diagnosis of MS was made according to the National Cholesterol Education Program Adult Treatment Panel III. Blood levels of insulin and proinsulin were measured, and the insulin resistance status was estimated using the homeostatic model assessment (HOMA-IR). The prevalence of MS was 10.1 percent. HOMA-IR was the best MS risk factor for both women and men (OR = 2.04; 95 percent CI: 1.68-2.48 and 1.09; 95 percent CI: 1.05-1.13, respectively). HOMA-IR presented the best positive predictive value for MS: 22 percent and 36 percent for men and women, respectively, and was the best MS indicator. The proinsulin/insulin ratio did not show significant association with MS. HOMA-IR, proinsulin, and insulin presented good negative predictive values for both genders that could be used to identify an at-risk population.

A síndrome metabólica (SM) constitui um fator de risco independente para doenças cardiovasculares. Existem evidências de que níveis sangüíneos de proinsulina e o índice proinsulina/insulina estão associados com a presença da SM. O objetivo deste trabalho foi comparar proinsulina e insulina, índice de resistência insulínica e o fator proinsulina/insulina para predizer a presença da SM. Este é um estudo transversal envolvendo 440 homens e 556 mulheres com média de 24 anos de idade. O diagnóstico da SM foi feito de acordo com o Painel III do programa de tratamento nacional educacional de colesterol para adultos. Níveis sangüíneos de insulina e proinsulina foram medidos, o índice de resistência insulínica foi estimado através do modelo de avaliação hemostático (HOMA-IR). A prevalência da SM foi de 10 por cento. HOMA-IR demonstrou ser o melhor fator de risco da SM em homens e mulheres (OR = 2,04; 95 por cento CI: 1,68-2,48 e 1,09; 95 por cento CI: 1,05-1,13, respectivamente). HOMA-IR apresentou o melhor valor preditivo positivo para SM: 22 por cento e 36 por cento para homens e mulheres, respectivamente, e foi o melhor indicador da SM. O índice proinsulina/insulina não apresentou associação significativa com SM. HOMA-IR, proinsulina e insulina apresentaram bons valores preditivos negativos para ambos sexos, o que poderia ser usado para identificar uma população de risco.

Expression of human proinsulin gene in pet 28A (+) vector and escherichia coli BL21 (DE3)

Background: Insulin is a hormone produced by the beta \r\n', u'cells of the pancreas that permits glucose to enter cells and \r\n', u'helps the body use glucose for energy. Insulin controls the \r\n', u'amount of glucose in the blood. Insulin is produced by recombinant protein technology. Expression of human proinsulin is the first step to express insulin. Objectives:To express successfully human proinsulin gene in pET 28a vector and E.coli BL21 (DE3). Subjects and method: Human proinsulin gene was applied from human pencreas cDNA by PCR using specific PINS primer pairs which contained sites for BamH I, Xho I. Proinsulin gene was cloned into pET 28a (+) vector to form recombinant vector pET 28a-PINS then transformed into E.coli BL21 (DE3) host strain to make pET 28a-PINS/ BL21 (DE3) clone. The clone was cultured and induced by IPTG (1mM). Recombine protein was analysed by SDS-PAGE. Results: Expression vector pET 28a-PINS was constructed successfully. Proinsulin protein expressed in E.coli BL21 (DE3) was purified by ProPond-Resin (Amersham). Conclusion: Human proinsulin was produced successfully using pET 28a-PINS/ BL21 (DE3) system.\r\n', u'

Cloning,expression and purification of recombinant human proinsulin C-peptide in E.coli / 中国药科大学学报

Aim:To obtain recombinant human proinsulin C-peptide,a novel expression vector pEDCC was constructed to facilitate the expression and purification of C-peptide. Methods:Gene fragments encoding a truncated asparaginase fragment mutant,native C-peptide,a hinge fragment of human IgG1,an extra acid-labile dipeptide and a basic-amino-acid-riched octopeptide were introduced in turn into plasmid pET28a. The fusion protein ansB-C-hinge-DPKRKRKKSRNGSGR-C-peptide was expressed effectively as inclusion bodies after induced by lactose and partially purified by means of washing and ethanol fractionation. After being hydrolyzed,the polypeptide PKRKRKKSRNGSGR-C-peptide was liberated from the fusion partner. The N-terminal tetradecapeptide extension of C-peptide was subsequently cleaved by trypsin and removed by DE52 column. Results:The nucleotides sequence of plasmid pEDCC was confirmed to be identical with that of designed fusion protein. Recombinant human proinsulin C-peptide was obtained with high purity after purification. Conclusion:Employing truncated asparaginase as the fusion partner and basic-amino-acid-riched octopeptide to modulate isoelectric point is an effective approach to produce recombinant human proinsulin C-peptide.

Complex Partial Seizure Like Symptoms Presented by a Patient with Insulinoma and Hyperproinsulinemia / 대한간질학회지

Insulinoma with hyperproinsulinemia and normal serum insulin level is a rare disease. Because of the neuroglycopenic symptoms, the initial diagnosis tends to be made as epilepsy or as psychosis. A 43-year-old man was admitted to our hospital because of recurrent confusional episodes. Symptoms are intermittent and consist of staring, confusion, amnesia, and bizarre behavior. Vital signs during the episode were normal but the serum glucose level was 27 mg/dl. The serum level of insulin during the episode was lower than normal and those of proinsulin and growth hormone were higher than normal. Solitary pancreatic mass was found by abdominal CT, measuring 15 mm in diameter. Pathologic evaluation showed islet cell tumor. This suggests that the serum level of proinsulin should be checked when insulinoma with neuroglycopenic symptom is suspected.