| 1. |
- Abdelgadir, M, et al.
(författare)
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Reduced leptin concentrations in subjects with type 2 diabetes mellitus in Sudan.
- 2002
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Ingår i: Metabolism, Clinical and Experimental. - : Elsevier BV. - 1532-8600. ; 51:3, s. 304-306
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Tidskriftsartikel (refereegranskat)abstract
- Differences have been observed in the relationship between leptin and metabolic perturbations in glucose homeostasis. Because no information is available from indigenous African populations with diabetes, the purpose of this study was to investigate the possible associations between leptin and different clinical and biochemical characteristics of a large group of subjects with type 2 diabetes mellitus in Sudan. A total of 104 (45 men and 59 women) consecutive type 2 diabetes patients and 75 control subjects (34 men and 41 women) were studied. The body mass index (BMI), blood glucose, serum insulin, and proinsulin were measured and related to serum leptin concentrations. Leptin was higher in females than in males and correlated significantly to BMI. The main novel finding was that serum leptin was significantly lower in diabetic subjects compared with controls in both females (P =.0001) and males (P =.019), although BMI did not differ between diabetic and nondiabetic subjects. Diabetic subjects treated with sulphonylurea (n = 81) had lower BMI than those treated with diet alone or other hypoglycemic drugs (n = 23) (P =.0017), but there was no difference in leptin levels between the 2 groups after adjustment for BMI (P =.87). In diabetic subjects, serum leptin correlated positively with the homeostatic assessment (HOMA) of both beta-cell function (P =.018) and insulin resistance (P =.038), whereas in control subjects, leptin correlated with insulin resistance (P =.0016), but not with beta-cell function. Diabetic subjects had higher proinsulin levels (P =.0031) and higher proinsulin to insulin ratio (P =.0003) than nondiabetic subjects. In univariate analysis, proinsulin showed a weak correlation to leptin (P =.049). In conclusion, we show in a large cohort of Sudanese subjects with type 2 diabetes that circulating leptin levels are lower in diabetic subjectss than in controls of similar age and BMI. The lower serum leptin in diabetic subjects may be a consequence of differences in fat distribution.
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| 4. |
- Agardh, Carl-David, et al.
(författare)
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Expression of antioxidant enzymes in rat retinal ischemia followed by reperfusion.
- 2006
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Ingår i: Metabolism, Clinical and Experimental. - : Elsevier BV. - 1532-8600. ; 55:7, s. 892-898
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate the expression and protein levels of antioxidant enzymes in the rat retina exposed to oxidative stress induced by ischemia-reperfusion injury. Retinal ischemia was induced in female Wistar rats by ligation of the optic nerve and vessels behind the left eye bulb, and was followed by reperfusion for 0, 3, 6, or 24 hours. The right eye served as control. RNA and protein were extracted simultaneously from each retina. Expressions of the endogenous antioxidant enzymes glutathione peroxidase (GPx1), catalase (CAT), copper/zinc superoxide dismutase, manganese superoxide dismutase, and the catalytic subunit of glutamylcysteine ligase (GCLc) were analyzed with real-time reverse transcription polymerase chain reaction and related to the endogenous control cyclophilin B. Protein levels were measured with Western blot analysis. During the early phase (0 or 3 hours) of reperfusion, no changes were seen in enzyme expression. After 6 hours, GCLc expression increased by a factor of 1.14 (P =.034), followed by a decline of 0.80 after 24 hours (P =.00004), according to the comparative Ct method. After 24 hours of reperfusion, GPx1 expression increased by a factor of 1.14 (P =.028), and CAT had decreased by 0.82 (P =.022). Expressions of copper/zinc superoxide dismutase and manganese superoxide dismutase showed a tendency toward a decrease by factors of 0.86 (P =.055) and 0.88 (P =.053), respectively, after 24 hours. Protein levels did not differ for any of the antioxidants, regardless of reperfusion time. The slightly increased messenger RNA expression of GPx1 after 24 hours of reperfusion with a concomitant very modest decrease in CAT and GCLc expression and no change in protein levels indicate a very modest, if any, response to oxidative stress generated by ischemia followed by reperfusion in rat retina.
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| 5. |
- Agardh, Carl-David, et al.
(författare)
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Glutathione levels are reduced in diabetic rat retina but are not influenced by ischemia followed by recirculation
- 1998
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Ingår i: Metabolism, Clinical and Experimental. - 1532-8600. ; 47:3, s. 269-272
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Tidskriftsartikel (refereegranskat)abstract
- Free radicals have recently been proposed to play a role in the development of diabetic retinopathy. The aim of the present study was to examine whether the abnormal metabolism caused by diabetes and by ischemia followed by recirculation interferes with a free radical enzyme defense system in the retina, ie, glutathione. Diabetes mellitus was induced by injecting streptozotocin ([STZ] 60 mg/kg body weight [BW] intraperitoneally). After 2 and 6 months, respectively, glutathione levels were measured in the retina and compared against those of age-matched normal control rats. Retinal ischemia was induced by careful ligation of the vessels and the accompanying optic nerve behind the left eye bulb. The right eye served as a control. After 90 minutes of ischemia, retinal circulation was reestablished by removing the ligature. Two-month-old diabetic rats were kept for an additional 3 days and normal rats for 5 minutes, 15 minutes, or 3 days before they were killed for measurement of glutathione. Retinal levels of glutathione were significantly lower in 6-month diabetic compared with 2-month diabetic rats (16.6 +/- 2.9 v 19.0 +/- 2.2 nmol/mg protein, P < .05) and 6-month normal control rats (16.6 +/- 2.9 v 21.0 +/- 2.1 nmol/mg protein, P < .001). Ischemia followed by recirculation did not influence the total tissue level of glutathione either in 2-month-old diabetic rats or in normal rats. The present study indicates that the abnormal metabolism caused by diabetes, rather than by changes in retinal circulation, results in an impaired defense mechanism against free radicals, a factor that may be of importance for the development of diabetic retinopathy. However, since glutathione levels in the present study were measured in the whole retina, it cannot be excluded that particular cell types, such as vascular cells, show an alteration in glutathione that is masked by the glutathione levels in the other nonvascular cells of the retina. Studies using other techniques are needed to further explore this subject.
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| 6. |
- Agardh, Carl-David, et al.
(författare)
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The influence of plasma insulin concentrations on tissue insulin levels in rodents: a study of the diabetic Chinese hamster and the ob/ob mouse
- 1986
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Ingår i: Metabolism, Clinical and Experimental. - : Elsevier BV. - 1532-8600. ; 35:3, s. 244-249
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Tidskriftsartikel (refereegranskat)abstract
- Immunoreactive insulin was measured in acid-ethanol extracts of kidney, brain, liver, and heart from genetically diabetic Chinese hamsters and their nondiabetic controls and from obese (ob/ob) mice and their thin littermates. Selected samples were filtered on Sephadex G-50 columns and the insulin concentration determined. There was a good correlation between the insulin level measured in the acid-ethanol extracts of tissues and the insulin level after gel filtration, suggesting that the concentration measured in the whole extract is representative of the true insulin content. The present data demonstrate that different extrapancreatic organs contain characteristic amounts of insulin that are often (sometimes several-fold) higher than the insulin level of plasma. The tissue insulin concentrations also exhibit a wide range of values, with occasional high values. The data also show a direct correlation between plasma and kidney insulins but no relationship between plasma and brain insulins and a mixed correlation among plasma and liver and heart insulins.
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| 7. |
- Agardh, Elisabet, et al.
(författare)
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Modifying a standard method allows simultaneous extraction of RNA and protein, enabling detection of enzymes in the rat retina with low expressions and protein levels
- 2006
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Ingår i: Metabolism, Clinical and Experimental. - : Elsevier BV. - 1532-8600. ; 55:2, s. 168-174
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to evaluate messenger RNA and protein expression in limited amounts of tissue with low protein content. The Chomczynski method was used for simultaneous extraction of RNA, and protein was modified in the protein isolation step. Template mass and cycling time for the complementary DNA synthesis step of real-time reverse transcription-polymerase chain reaction (RT-PCR) for analysis of catalase, copper/zinc superoxide dismutase, manganese superoxide dismutase, the catalytic subunit of glutamylcysteine ligase, glutathione peroxidase 1, and the endogenous control cyclophilin B (CypB) were optimized before PCR. Polymerase chain reaction accuracy and efficacy were demonstrated by calculating the regression (R2) values of the separate amplification curves. Appropriate antibodies, blocking buffers, and running conditions were established for Western blot, and protein detection and multiplex assays with CypB were performed for each target. During the extraction procedure, the protein phase was dissolved in a modified washing buffer containing 0.1% sodium dodecyl sulfate, followed by ultrafiltration. Enzyme expression on real-time RT-PCR was accomplished with high reliability and reproducibility (R2, 0.990-0.999), and all enzymes except for glutathione peroxidase 1 were detectable in individual retinas on Western blot. Western blot multiplexing with CypB was possible for all targets. In conclusion, connecting gene expression directly to protein levels in the individual rat retina was possible by simultaneous extraction of RNA and protein. Real-time RT-PCR and Western blot allowed accurate detection of retinal protein expressions and levels.
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| 8. |
- Ahrén, Bo, et al.
(författare)
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Differential impairment of glucagon responses to hypoglycemia, neuroglycopenia, arginine, and carbachol in alloxan-diabetic mice.
- 2002
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Ingår i: Metabolism, Clinical and Experimental. - : Elsevier BV. - 1532-8600. ; 51:1, s. 12-19
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Tidskriftsartikel (refereegranskat)abstract
- To gain insight into the mechanisms responsible for the loss of the glucagon response to insulin-induced hypoglycemia in type 1 diabetes, glucagon responses to 4 different stimuli were examined over 3 months of diabetes in alloxan-treated mice. At 1, 6, and 12 weeks after alloxan (60 mg/kg), phloridzin (0.1 g/kg) was administered to overnight fasted diabetic mice to match the glucose levels of those in nondiabetic control mice before administration of the acute stimuli. Despite the elevation of baseline glucagon levels produced by the phloridzin treatment, the glucagon responses to insulin (2 U/kg intraperitoneally [IP])-induced hypoglycemia was not impaired at 1 week. However, the response was reduced by greater than 60% after 6 and 12 weeks of diabetes (P <.05). In contrast, the glucagon response to arginine (0.25 g/kg intravenously [IV]) was not reduced after 1, 6, or 12 weeks of diabetes, ruling out a generalized impairment of the A-cell responses. The glucagon response to the neuroglucopenic agent, 2-deoxyglucose (2-DG; 500 mg/kg IV) was impaired, like that to insulin-induced hypoglycemia, after 6 and 12 weeks of diabetes (P <.05), suggesting that supersensitivity to the potential inhibitory effects of exogenous insulin is not the mechanism responsible for the impairment. Finally, the glucagon response to the cholinergic agonist, carbachol (0.53 micromol/kg IV), was not impaired in the diabetic animals, arguing against a defect in the A-cell's responsiveness to autonomic stimulation. The data suggest that the impairment of the glucagon response to insulin-induced hypoglycemia in alloxan diabetic mice is not due to a generalized impairment of A-cell responsiveness, to desensitization by a suppressive action of insulin, or to impairment of the A-cell response to autonomic stimuli. The remaining mechanisms which are likely to explain the late loss of the glucagon response to insulin-induced hypoglycemia include (1) a defect in the A-cell recognition of glucopenic stimuli, or (2) a defect in the autonomic inputs to the A cell that are known to be activated by glucopenic stimuli.
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| 9. |
- Annerbrink, Kristina, 1974, et al.
(författare)
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Catechol O-methyltransferase val158-met polymorphism is associated with abdominal obesity and blood pressure in men.
- 2008
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Ingår i: Metabolism. - : Elsevier BV. - 0026-0495 .- 1532-8600. ; 57:5, s. 708-711
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Tidskriftsartikel (refereegranskat)abstract
- Catechol O-methyltransferase (COMT) degrades catecholamines and estrogens, both of which are of known importance for cardiovascular risk factors such as obesity and hypertension. The gene coding for COMT contains a val158-met polymorphism that exerts a considerable influence on enzymatic activity. We hypothesized that this polymorphism might influence risk factors for cardiovascular disease. Deoxyribonucleic acid samples and data regarding blood pressure and anthropometry were collected from 240 Swedish men, all 51 years old. Subjects homozygous for the low-activity allele (met) displayed higher blood pressure, heart rate, waist-to-hip ratio, and abdominal sagittal diameter as compared with heterozygous subjects, who in turn displayed higher blood pressure, heart rate, waist-to-hip ratio, and abdominal sagittal diameter than subjects homozygous for the high-activity allele (val). All measured variables were significantly correlated; however, the associations between COMT val158-met and cardiovascular variables, and the association between COMT val158-met and anthropometry, respectively, were partly independent of each other, as revealed by multiple linear regression.
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| 10. |
- Arnadottir, Margret, et al.
(författare)
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Corticotropin-induced reduction of plasma lipoprotein(a) concentrations in healthy individuals and hemodialysis patients: relation to apolipoprotein(a) size polymorphism
- 1999
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Ingår i: Metabolism, Clinical and Experimental. - 1532-8600. ; 48:3, s. 342-346
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Tidskriftsartikel (refereegranskat)abstract
- Lipoprotein(a) [Lp(a)], a strong independent cardiovascular risk factor, consists of the unique apolipoprotein(a) [apo(a)] covalently linked to a low-density lipoprotein particle. Apo(a) contains a widely differing number of the plasminogen-like kringle IV, a size polymorphism that is codominantly inherited. In addition to powerful genetic control, renal failure is known to influence the plasma Lp(a) concentration. There is still a lot to be learned about the mode and site of catabolism of Lp(a), and there is no readily applicable Lp(a)-lowering treatment available. Therefore, it was of interest to study further the Lp(a)-lowering effect of corticotropin (ACTH) that has been demonstrated in small studies. The main purpose of the present study was to investigate the influence of ACTH on different apo(a) isoforms. Short-term treatment with ACTH decreased the plasma Lp(a) concentration in all 26 study participants. The two study groups (12 healthy individuals and 14 hemodialysis patients) responded similarly, with a median decrease in plasma Lp(a) of 39% and 49%, respectively. In subjects with two clearly separable apo(a) bands, apo(a) phenotyping and densitometric scanning of the bands before and after treatment with ACTH revealed a change in the proportion of apo(a) isoforms, ie, a shift toward the isoform with lower molecular weight. This was observed in seven of nine investigated subjects (four of five healthy individuals and three of four hemodialysis patients).
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