Adriana Augusto de Rezende

Osteopenia: a bone disorder associated with diabetes mellitus

Although osteopenia has been associated with human diabetes mellitus, the pathogenesis of diabetic osteopenia is unclear. In the present study, we evaluated the effect of diabetes on histomorphometry, bone mineral density (BMD)—measured by dual-energy X-ray absorptiometry (DXA)—and biomarkers of bone metabolism in rats up to 120 days after the onset of experimental diabetes. Female Wistar rats with a regular estrous cycle were randomly divided into two groups: control rats (n = 15) and diabetic rats without insulin treatment (n = 25). Diabetes was induced by injection of alloxan and was confirmed by the determination of blood glucose concentration (>250 mg/dl). The results revealed an approximate threefold increase of femoral trabecular distance in diabetic rats compared to controls. Conversely, trabecular thickness and bone trabecular volume were reduced twofold and 77%, respectively. BMD in both the metadiaphyseal region and total area of the femur was found to be clearly reduced in diabetic animals, with no significant differences between the groups. Serum alkaline phosphatase (ALP) and tartarate-resistant acid phosphatase (TRAP) activities showed significant six- and twofold increases, respectively, in diabetic rats. There were significant decreases in serum calcium and albumin concentrations in diabetic rats, but no difference was observed in serum magnesium, phosphorus, or creatinine concentrations between the groups. Overall, our findings support the conclusion that the diabetic state is associated with alterations in bone turnover, resulting in the development of osteopenia, which is related to the time of evolution of the disorder.

Low bone mineral density is associated to poor glycemic control and increased OPG expression in children and adolescents with type 1 diabetes

AIMS To investigate early alterations on bone mineral density (BMD) and RANK, RANKL and OPG mRNA expression in peripheral blood leukocytes (PBL) in children and adolescents with type 1 diabetes (T1D) and the relationship with glycemic control and bone biomarkers. METHODS This cross-sectional study included 75 children and adolescents with T1D and 100 individuals without diabetes (normoglycemic-NG) aged 6-20 years old. T1D individuals were considered to have good (T1DG) or poor (T1DP) glycemic control according to the values of HbA1c. Phosphorus, magnesium, total and ionized calcium, osteocalcin, alkaline phosphatase and tartaric-resistant acid phosphatase (TRAP) values were determined in blood samples. BMD was measured by DEXA. RANK, RANKL and OPG mRNA expression was measured in PBL by real-time PCR. RESULTS Osteocalcin values were decreased in diabetic groups in comparison to NG group (p<0.05), and a negative correlation with both serum glucose (r=-0.265, p<0.01) and Hb1Ac (r=-0.252, p<0.01) in T1D group was found. BMD was lower in diabetic groups in comparison with NG group (p<0.05) and a negative correlation was observed between BMD and both serum glucose (r=-0.357, p<0.01) and HbA1c (r=-0.351, p<0.01) in T1D group. OPG mRNA expression was significantly increased in T1D and T1DP groups in comparison with NG group (p<0.05). In conclusion, children and adolescents with early onset T1D presented low bone mineral density associated to unsatisfactory glycemic control, increased OPG mRNA expression and low osteocalcin concentration.

Beneficial effects of oral chromium picolinate supplementation on glycemic control in patients with type 2 diabetes: A randomized clinical study.

BACKGROUND Chromium is an essential mineral that contributes to normal glucose function and lipid metabolism. This study evaluated the effect of chromium picolinate (CrPic) supplementation in patients with type 2 diabetes mellitus (T2DM). METHODS A four month controlled, single blind, randomized trial was performed with 71 patients with poorly controlled (hemoglobin A1c [HbA1c]>7%) T2DM divided into 2 groups: Control (n=39, using placebo), and supplemented (n=32, using 600μg/day CrPic). All patients received nutritional guidance according to the American Diabetes Association (ADA), and kept using prescribed medications. Fasting and postprandial glucose, HbA1c, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides and serum ferritin were evaluated. RESULTS CrPic supplementation significantly reduced the fasting glucose concentration (-31.0mg/dL supplemented group; -14.0mg/dL control group; p<0.05, post- vs. pre-treatment, in each group) and postprandial glucose concentration (-37.0mg/dL in the supplemented group; -11.5 mg/dL in the control group; p<0.05). HbA1c values were also significantly reduced in both groups (p<0.001, comparing post- vs. pre-treatment groups). Post-treatment HbA1c values in supplemented patients were significantly lower than those of control patients. HbA1c lowering in the supplemented group (-1.90), and in the control group (-1.00), was also significant, comparing pre- and post-treatment values, for each group (p<0.001 and p<0.05, respectively). CrPic increased serum chromium concentrations (p<0.001), when comparing the supplemented group before and after supplementation. No significant difference in lipid profile was observed in the supplemented group; however, total cholesterol, HDL-c and LDL-c were significantly lowered, comparing pre- and post-treatment period, in the control group (p<0.05). CONCLUSIONS CrPic supplementation had a beneficial effect on glycemic control in patients with poorly controlled T2DM, without affecting the lipid profile. Additional studies are necessary to investigate the effect of long-term CrPic supplementation.

Zinc pharmacokinetics in insulin-dependent diabetes mellitus patients after oral zinc tolerance test

Abstract Zinc is an essential micronutrient that is directly involved in the physiology of insulin, and zinc metabolism could play a role in the pathogenesis of diabetes mellitus and its complications. On the other hand, low zinc absorption and hyperzincuria in diabetic animals and humans have indicated that diabetics are more susceptible to zinc deficiency. This study was designed to compare zinc metabolism in ten insulin-dependent diabetic patients with ten healthy controls, using an oral zinc tolerance test. Pharmacokinetic parameters were performed to study intestinal zinc absorption and urinary zinc excretion. Absorption of zinc was extensive during the first two hours after administration of a single oral dose of 25 mg Zn ++ . The area under the serum zinc curve (AUC) and maximum concentration of zinc (C max ) did not differ in both control and experimental groups, p a ), elimination rate constant (K el ), absorption half-life (T 1/2a ), elimination half-life (T 1/2el ), and time of maximum concentration (T max ) were not significantly different between the diabetic patients and controls ( p > 0.05). All these kinetic parameters suggest that there is no malabsorption of zinc in diabetic patients. Conversely, zinc clearance/creatinine clearance ratio (CZn ++ /Ccr ratio) in diabetic patients differed significantly in comparison to controls, p

Protection against T1DM-Induced Bone Loss by Zinc Supplementation: Biomechanical, Histomorphometric, and Molecular Analyses in STZ-Induced Diabetic Rats

Several studies have established an association between diabetes and alterations in bone metabolism; however, the underlying mechanism is not well established. Although zinc is recognized as a potential preventive agent against diabetes-induced bone loss, there is no evidence demonstrating its effect in chronic diabetic conditions. This study evaluated the effects of zinc supplementation in a chronic (90 days) type 1 diabetes-induced bone-loss model. Male Wistar rats were distributed in three groups: control, type 1 diabetes mellitus (T1DM), and T1DM plus zinc supplementation (T1DMS). Serum biochemical analysis; tibia histomorphometric, biomechanical, and collagen-content analyses; and femur mRNA expression were evaluated. Relative to T1DM, the zinc-supplemented group showed increased histomorphometric parameters such as TbWi and BAr and decreased TbSp, increased biomechanical parameters (maximum load, stiffness, ultimate strain, and Young’s modulus), and increased type I collagen content. Interestingly, similar values for these parameters were observed between the T1DMS and control groups. These results demonstrate the protective effect of zinc on the maintenance of bone strength and flexibility. In addition, downregulation of OPG, COL1A, and MMP-9 genes was observed in T1DMS, and the anabolic effects of zinc were evidenced by increased OC expression and serum ALP activity, both related to osteoblastogenesis, demonstrating a positive effect on bone formation. In contrast, T1DM showed excessive bone loss, observed through reduced histomorphometric and biomechanical parameters, characterizing diabetes-associated bone loss. The bone loss was also observed through upregulation of OPG, COL1A, and MMP-9 genes. In conclusion, zinc showed a positive effect on the maintenance of bone architecture and biomechanical parameters. Indeed, OC upregulation and control of expression of OPG, COL1A, and MMP-9 mRNAs, even in chronic hyperglycemia, support an anabolic and protective effect of zinc under chronic diabetic conditions. Furthermore, these results indicate that zinc supplementation could act as a complementary therapy in chronic T1DM.

A multicentric association study between 39 genes and nonsyndromic cleft lip and palate in a Brazilian population.

PURPOSE The aim of this study was to use the TaqMan OpenArray system to evaluate associations between 39 genes and the etiology of nonsyndromic cleft lip and palate (NSCLP) in a Brazilian population. MATERIAL AND METHODS This case-control association study was designed with 80.11% statistical power according to logistic regression (GPOWER software). The case group had 182 patients with NSCLP enrolled in the Brazilian Database on Orofacial Clefts. The controls included 355 healthy individuals with no history of oral clefting in the past three generations. All samples were genotyped for 253 tag single nucleotide polymorphisms (tagSNPs) in 39 genes, including two that had recently been associated with this process. The association analysis was performed using logistic regression and stepwise regression. The results were corrected for multiple testing [Bonferroni correction and False Discovery Rate (FDR)]. RESULTS Twenty-four SNPs in 16 genes were significantly associated with the etiology of NSCLP, including MSX1, SPRY1, MSX2, PRSS35, TFAP2A, SHH, VAX1, TBX10, WNT11, PAX9, BMP4, JAG2, AXIN2, DVL2, KIF7, and TCBE3. Stepwise regression analysis revealed that 11 genes contributed to 15.5% of the etiology of NSCLP in the sample. CONCLUSION This is the first study to associate KIF7 and TCEB3 with the etiology of NSCLP. New technological approaches using the same design should help to identify further etiological susceptibility variants.

Evaluation of antioxidant parameters in rats treated with sevoflurane.

BACKGROUND AND OBJECTIVES Sevoflurane is a halogenated fluorinated ether that undergoes hepatic biotransformation through cytochrome P4502E1. Halogenated ethers undergoing biotransformation by P4502E1 can produce reactive oxygen species (ROS), weakening the antioxidant defense mechanism. The objective of this study was to investigate the relationship between the activity of erythrocyte antioxidant enzymes and sevoflurane. METHODS Animals were divided in four groups: Group 1 - control: 100% oxygen (1 L.min(-1) for 60 min during five consecutive days); Group 2 - 4.0% sevoflurane in 100% oxygen (1 L.min(-1) for 60 minutes during five consecutive days); Group 3 - isoniazid (i.p.), 50 mg.kg(-1)/ day for four consecutive days, followed by 100% oxygen (1 L.min(-1) for 60 minutes during four consecutive days); Group 4 - intraperitoneal isoniazid, 50 mg.kg(-1) daily for four days, followed by 4.0% sevoflurane in 100% oxygen (1 L.min(-1) for 60 minutes during five days). Twelve hours after the last exposure to sevoflurane, animals were sacrificed and their blood was collected through the portal vein for analysis of antioxidant enzymes. RESULTS An increase in the activity of glucose-6-phosphate dehydrogenase and a decrease in the activity of catalase were observed, especially in the group of animals pre-treated with isoniazid. Changes in the activity of glutathione peroxidase were not observed. CONCLUSIONS The interaction between sevoflurane and cytochrome P450 2E1 with enzymatic inducers can lead to oxidative stress with prolonged and repetitive exposure.

Association of polymorphisms in IL6 gene promoter region with type 1 diabetes and increased albumin-to-creatinine ratio.

Pro‐inflammatory cytokines, such as interleukin‐6 (IL‐6), have been considered as key factors in type 1 diabetes mellitus (T1DM) and diabetic nephropathy, thus, our aim was to investigate the association of IL6‐174G>C (rs1800795) and ‐634C>G (rs1800796) polymorphisms with T1DM susceptibility and diabetic nephropathy.

Sensitivity of zinc kinetics and nutritional assessment of children submitted to venous zinc tolerance test.

Objective: The purposes of this study were to investigate the kinetics of zinc in schoolchildren between the ages of 6 and 9 years, of both sexes, and to verify its sensitivity in detecting alterations in body zinc status. Methods: Nutritional assessment was performed by body mass index. Food intake, venous zinc tolerance test, and zinc kinetics were carried out before and after 3-month oral zinc supplementation. Results: Of the 42 children studied, 76.2% had healthy weight. Only energy, calcium, and fiber intake were suboptimal before and after oral zinc supplementation. Serum zinc and total-body zinc clearance, although at normal levels, increased significantly after zinc supplementation. Conclusion: We concluded, therefore, that kinetics is a sensitive tool for detecting changes in body zinc status, even in children without a deficiency of this mineral. Furthermore, kinetics showed a positive response to supplementation and may be a sensitive parameter for evaluating the efficacy of this therapy.

Increased TLR2 expression in patients with type 1 diabetes: evidenced risk of microalbuminuria

Ururahy MAG, Loureiro MB, Freire‐Neto FP, Souza KSC, Zuhl I, Brandão‐Neto J, Hirata RDC, Doi SQ, Arrais RF, Hirata MH, Almeida MG, Rezende AA. Increased TLR2 expression in patients with type 1 diabetes: evidenced risk of microalbuminuria.