Proinflammatory cytokines in response to insulin-induced hypoglycemic stress in healthy subjects

Hyperglycemic crises of diabetic ketoacidosis and nonketotic hyperglycemia are associated with elevation of counterregulatory hormones and proinflammatory cytokines, markers of lipid peroxidation, and oxidative stress. To investigate if other conditions besides hyperglycemia could evoke such a prompt increase in cytokine levels, lipid peroxidation, and oxidative stress markers, we induced hypoglycemic stress by standard insulin tolerance test and measured proinflammatory cytokines, markers of lipid peroxidation, reactive oxygen species (ROS), and counterregulatory hormones. Insulin tolerance test was performed in 13 healthy male subjects with no history of infection, cardiovascular risk factors, or abnormal glucose. At baseline and at 30, 45, 60, 120, and 240 minutes after insulin injection, the following parameters were measured: glucose, cortisol, corticotropin, epinephrine (EP), norepinephrine (NE), growth hormone, tumor necrosis factor (TNF)-α, interleukin (IL) 1β, IL-6, IL-8, free fatty acids, white blood cells, lipid peroxidation markers by thiobarbituric acid assay, and ROS by dichlorofluorescein method. The peak value of white blood cell count at 120 minutes was significantly associated with the peak values of NE at 30 minutes and cortisol at 60 minutes. By comparing the area under the curve of measured parameters, EP emerged as significant predictor of TNF-α (P = .05) and IL-8 (P = .027). Cortisol emerged as predictor of IL-1β significantly (P = .05). Corticotropin predicted area under the curve of IL-6 with borderline significance (P = .06). In the present study, insulin-induced hypoglycemia in nondiabetic male subjects is associated with increased proinflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-8), markers of lipid peroxidation, ROS, and leukocytosis. Elevations of NE, EP, corticotropin, and cortisol in hypoglycaemia are associated with the elevation of the proinflammatory cytokines and leukocytosis.     

Would blockage of cytokines improve the outcome of pancreatic islet transplantation?

It has been estimated that up to 60% of pancreatic islet tissue undergoes apoptosis within the first several days post-transplantation. This strongly suggests the involvement of an inflammatory event other than alloantigen-specific immune reaction following islet transplantation which contributes to partial destruction of grafts. Inflammatory cytokines including IL-1beta, TNF-alpha and IFN-gamma are implicated in the pancreatic islet beta-cell death and functional loss during autoimmune diabetes and also seem to be involved in early loss of islet mass in islet transplantation. Inflammatory cytokines and free oxygen radicals released in situ could cause apoptosis and the functional impairment of islets after islet transplantation and graft failure. It can be hypothesized that preventing destruction of transplanted islets using cytokine blockade could be helpful in improving islet transplantation outcome. Several approaches have been made based on this hypothesis to examine the effect of inflammatory blockade on the islets survival and functional islet mass. Further investigations are required to identify most efficient way for block of cytokine-induced damage in pancreatic islets transplantation.     

The recombination difference between mouse kappa and lambda segments is mediated by a pair-wise regulation mechanism

In mice, kappa light chains dominate over lambda in the immunoglobulin repertoire by as much as 20-fold. Although a major contributor to this difference is the recombination signal sequences (RSS), the mechanism by which RSS cause differential representation has not been determined. To elucidate the mechanism, we tested kappa and lambda RSS flanked by their natural 5' and 3' flanks in three systems that monitor V(D)J recombination. Using extra-chromosomal recombination substrates, we established that a kappa RSS and its flanks support six- to nine-fold higher levels of recombination than a lambda counterpart. In vitro cleavage assays with these same sequences demonstrated that single cleavage at individual kappa or lambda RSS (plus flanks) occurs with comparable frequencies, but that a pair of kappa RSS (plus flanks) support significantly higher levels of double cleavage than a pair of lambda RSS (plus flanks). Using EMSA with double stranded oligonucleotides containing the same kappa or lambda RSS and their respective flanks, we examined RAG/DNA complex formation. We report that, surprisingly, RAG-1/2 form only modestly higher levels of complexes on individual 12 and 23 kappa RSS (plus natural flanks) as compared to their lambda counterparts. We conclude that the overuse of kappa compared to lambda segments cannot be accounted for by differences in RAG-1/2 binding nor by cleavage at individual RSS but rather could be accounted for by enhanced pair-wise cleavage of kappa RSS by RAG-1/2. Based on the data presented, we suggest that the biased usage of light chain segments is imposed at the level of synaptic RSS pairs.     

Comparison of Harris Benedict and Mifflin-ST Jeor equations with indirect calorimetry in evaluating resting energy expenditure

Background: An understanding of energy expenditure in hospitalized patients is necessary to determine optimal energy supply. The metabolic rate can be measured or estimated by equations, but estimation is by far the most common method. AIM: This study tests the degree of agreement between measured resting energy expenditure by indirect calorimetry and predicted resting energy expenditure by Harris Benedict and Mifflin-St Jeor equations. Patients were categorized according to sex and diagnosis. Settings and Design: Cross-sectional study. Materials and Methods: In 60 randomly selected patients, aged between 18 and 83 years, resting energy expenditure (REE) was measured by indirect calorimetry and compared with the predicted equations of Harris Benedict and Mifflin-St Jeor. Statistical Analysis: Statistical analysis was performed by using the method of Bland-Altman, one sample t-test and Pearson's correlation. Results: There was no statistically significant difference between measured and predicted resting energy expenditure by both equations, in all cases as a whole and each group. The only statistically significant difference was seen between measured resting energy expenditure and its predicted equivalent by Mifflin-St equation when patients were categorized according to their sex. Limits of agreements were wide for both equations in all cases and each category so clinical significance was considerable. Conclusions: At a group level Harris-Benedict equation is suitable for predicting REE but at an individual level, both equations have wide limits of agreement and clinically important differences in REE would be obtained.     

Apelin 13: A novel approach to enhance efficacy of hypoxic preconditioned mesenchymal stem cells for cell therapy of diabetes

Recent studies have proposed cell therapy as an alternative therapeutic strategy for many disease states such as diabetes mellitus. Among different cell types mesenchymal stem cells (MSC) have attracted a significant attention based on their intriguing potentials. However MSC therapy is limited as a large portion of transplanted cells undergo apoptosis after transplantation. Therefore, proposing a strategy to overcome this obstacle may be of great value. Recent studies have shown that hypoxia preconditioning (HPC) may improve cell viability after transplantation. Both HPC and hyperglycemia are reported to exert effects by different levels of ROS overproduction. Overdose of ROS in this case would trigger the apoptosis and thereby decreased cell viability after transplantation. Apelin; the endogenous ligand for the previously orphaned G protein–coupled receptor APJ is shown to exert anti apoptotic effects On oxidative stress-induced apoptosis in MSCs via MAPK/ERK1/2 and PI3K/AKT signaling pathways. Accordingly it has been hypothesized that pretreatment of HPC-MSC_s with apelin 13 would be an effective approach to modify and possibly enhance the efficacy of MSCs in cell therapy of diabetes.     

Poly thymidine polymorphism and cystic fibrosis in a non-Caucasian population

Background: Cystic fibrosis is a monogenic recessive disorder found predominantly in Caucasian population. This disease arises from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. In this study we consider poly T polymorphism c.1210-12T[5], c.1210-12T[7], c.1210-12T[9] (T₅, T₇, T₉) in the intron 8 of CFTR gene in normal individuals and cystic fibrosis patients in the north of Iran. Material and methods: 40 CF patients and 40 normal individuals were screened for poly T polymorphism in intron 8 of CFTR gene using Reverse Dot Blot method which was also used to detect p.Phe508del among CF patients. Results: T₇ allele is the most prevalent in both normal and CF patients. Its abundance is approximately 75%. T₉ and T₅ represent approximately 20% and 5% of alleles respectively. T₇/ T₇ genotype is the most present in both normal and CF patients with 72.5% and 60% prevalence respectively. p.Phe508del was present in 13 CFTR alleles belonging to 7 patients with either homozygote T₉/ T₉, T₇/ T₇ or compound heterozygote T₇/ T₉ genotypes. Conclusion: Contrary to the Caucasians, T₇ allele is more frequent in Northern Iranian CF patients. The presence of p.Phe508del and T₇ allele in the same framework is reported for the first time in this part of the world. Further investigations of other populations will help to understand whether p.Phe508del arose by selection pressure in this part of the world or was imported from European countries. The abundance of T₅, T₇, T₉ alleles indicates that this polymorphism can be used as one of the informative markers for detection of normal and mutant alleles in prenatal diagnosis or carrier assessment in families with previous history of the disease in regions with high degree of CFTR mutation heterogeneity.