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Biological markers for Metabolic Syndrome, such as serum lipids and Hemoglobin A1c may have genetic variability among African Americans versus their Caucasian American counterparts. Although cases of Type 2 diabetes and its sequela significantly outweigh Caucasian Americans in the US, paradoxically research has found a lower prevalence of Metabolic Syndrome among blacks versus whites despite there being higher rates of Type 2 diabetes among the former population. Research has shown Metabolic Syndrome lipid parameters among African Americans are more favorable despite outstanding Type 2 diabetes incidence. With the emergence of the Human Genome Project and Genome Wide Association Studies, genetic differences in these parameters have been uncovered and genetic variability may play a role in such paradoxical mismatch. It may be reasonable to consider modifying Metabolic Syndrome parameters as given this new biological evidence. Hemoglobin A1c, also a biological marker used to monitor glucose levels over time, shows variability in its measurements with respect to African Americans. Genetic factors may play a role in the discrepancies among African Americans populations when using this parameter to monitor blood glucose. Precision medicine is now at the forefront of a biomedical new age, to find therapies that cater to specific populations based on genetic research. African Americans may not benefit from such a revolutionary paradigm shift in medicine due to evidence of lack of inclusivity in such studies like the Human Genome Project. Consideration should be made to the future of molecular medicine to include more minority populations such as African Americans in order to cater to specific differences rather than generalized standards of care.

Objective:MicroRNAs (miRNA) are novel critical regulators of cell proliferation and human disease, including diabetes mellitus and cancer. The aim of this study was to evaluate the expression of circulating erythrocytes (E) miRNA-144 and miRNA-451 expression in African Americans Adults (AAA) as a biomarker of cell aging.Methods:The blood samples were collected from healthy controls [n=9] following an 8-12 hours fast. Erythrocytes were purified twice by Boyum gradient. Erythrocytes were further sub-fractionated into young (y) (1.07-1.09 g/ml), mid (m) (1.09- 1.11 g/ml), and old (o) (1.11-1.12 g/ml) age cells by using discontinuous Percoll gradient (35%, 40%, 45%, 50%, 55%, 65%, 80%, and 100%) and total RNA extracted. MiRNA-144 and miRNA-451 were quantified in y, m, and o age E sub-fractions by qRT-PCR.Results:MiRNA-451 expression was 82210.8271, 130922.476, and 149554.364 in y, m, and o cells, respectively. MiRNA-144 expression in y cells was 18.6641092, m cells was 32.4413621, and o cells was 57.8118394 These results showed that o cells expressed both miRNA-144 and miRNA-451 more than that of m, and y cells.Conclusion:The findings of this study showed that miRNAs expression differ in sub-fractionated erythrocytes. This study suggests that miRNA-144 and miRNA-451 have the potential to be used as biomarkers of RBC aging.

The prevalence of diabetes mellitus (DM) is increasing at a staggering rate around the world. In the United States, more than 30.3 million Americans have DM. Type 2 diabetes mellitus (T2DM) accounts for 91.2% of diabetic cases and disproportionately affects African Americans and Hispanics. T2DM is a major risk factor for cardiovascular disease (CVD) and is the leading cause of morbidity and mortality among diabetic patients. While significant advances in T2DM treatment have been made, intensive glucose control has failed to reduce the development of macro and microvascular related deaths in this group. This highlights the need to further elucidate the underlying molecular mechanisms contributing to CVD in the setting of T2DM. Endothelial dysfunction (ED) plays an important role in the development of diabetes-induced vascular complications, including CVD and diabetic nephropathy (DN). Thus, the endothelium provides a lucrative means to investigate the molecular events involved in the development of vascular complications associated with T2DM. microRNAs (miRNA) participate in numerous cellular responses, including mediating messages in vascular homeostasis. Exosomes are small extracellular vesicles (40-160 nanometers) that are abundant in circulation and can deliver various molecules, including miRNAs, from donor to recipient cells to facilitate cell-to-cell communication. Endothelial cells are in constant contact with exosomes (and exosomal content) that can induce a functional response. This review discusses the modulatory role of exosomal miRNAs and proteins in diabetes-induced endothelial dysfunction, highlighting the significance of miRNAs as markers, mediators, and potential therapeutic interventions to ameliorate ED in this patient group.

Background C-peptide blood levels can indicate whether or not a person is producing insulin and roughly how much. C-peptide is secreted as a byproduct of the biosynthesis of insulin from proinsulin. C-peptide has proposed biological activity and a well-established diagnostic value. The significance of C-peptide concentration in the plasma and urine in the pediatric population needs further delineation. Aim: To determine the significance of plasma C-peptide in obese African American adolescents with mild insulin resistance but no evidence of diabetes. Methods This study included 19 African American adolescents with body mass index (BMI) in at least the 85th percentile evaluated with anthropometric measurements, Homeostatic Model Assessment-Insulin Resistance (HOMA-IR) score, and oral glucose tolerance test (OGTT), and 24-hour urine collections. The study also included an age-matched control group of 15 healthy African American adolescent controls and were not subjected for OGTT. The correlation among BMI, fasting plasma C-peptide concentrations, and 24-hour-urine C-peptide concentrations was calculated, t Tests were conducted to compare plasma C-peptide and 24-hour-urine C-peptide concentrations for the test group and controls. Results Mean HOMA score (3.96 ± 1.84) signified mild insulin resistance among the adolescent test group. The test subjects exhibited adequate glucose tolerance (glucose range, 89.4-122.5 mg/dL) during the OGTT. A significant positive relationship was observed between BMI and fasting plasma C-peptide concentration in the control group ( r = 0.537) but not the test group ( r = 0.335). An insignificant positive relationship was exhibited between BMI and 24-hour-urine C-peptide concentration in the test group ( r = 0.150) and controls ( r = 0.254). Conclusions The positive relationship among BMI, plasma C-peptide, and urine C-peptide is worth further evaluation in studies conducting multiple rounds of OGTT with a larger sample of pediatric subjects. The potential diagnostic value of C-peptide may facilitate early detection of insulin resistance in the pediatric population.

In this exploratory study, we investigated total erythrocyte carbonic anhydrase (CA) estrase activity as well as CA I isozyme concentration in patients with diabetes mellitus type II (DM) and healthy individuals of Howard University Hospital community. Total estrase activity of CA was measured spectrophotometrically using p-nitrophenol acetate before and after inhibition with acetazolamide. CA I isozyme was measured by radial immunodiffusion using monoclonal antibody (CA I) in agarose plates. The study involved 20 consented participants; 10 normal (N) and 10 (DM), 21 to 84 years of age. The study was approved by the Howard University Institution Review Board. The CA activity was measured following lysis of cells as U/min/mL and CA I concentration as mg/l. We observed CA activity as 46.3+/-4(N) and 25+/-2.1 (DM) whereas CA I concentration as 1896+/-125 (N) and 1104 +/-63 (DM). We speculate that the change in the CA activity may of fundamental importance in the regulation of intracellular; pH(i) for the basic control of metabolism in diabetes mellitus. Further, we propose that CA activity is a good candidate for a biomarker of diabetes mellitus for the early detection of insulin resistance because the CA activity variation was proportional to the severity of the diabetes.

We examined the long-term effects of enhanced Vitamin D (VitD) supplementation on parameters of type 2 diabetes mellitus (T2DM): serum hemoglobin A1c, low density lipoprotein, high density lipoprotein, and triglyceride for the purpose of determining beneficial VitD levels in T2DM African Americans (AA).Following inclusion criteria, retrospective charts of patients agedor = 30 years were reviewed. VitD supplementation was given to patients as part of drug regimen over a three year continuum. Pearson correlations were used to assess the relationship between VitD levels and levels of each parameter. Repeated measure analysis of variance was conducted to identify difference in mean levels of each parameter between years with VitD included as part of therapy.Vitamin D supplementation was inversely associated with HbA1c (r = -.286, P = .031). No correlation was found between levels of VitD and levels of LDL, HDL or TG. Hemoglobin A1c levels were found to be significantly different under VitD treatment between year 1 (mean VitD 24.75 microg/mL, mean HbA1c 9.15%, P = .000) and year 2 (mean VitD 33.84 microg/mL, mean HbA1c 7.91%, P = .000) and between year 1 and year 3 (mean VitD 34.46 microg/mL, mean 7.98% HbA1c P = .000).In T2DM AA, significant improvements in HbA1c are obtained with enhanced VitD supplementation as part of drug regimen over time. Our investigation provides the first known evidence of a relationship between enhanced VitD supplementation as part of a pre-existing medical regimen taken over long term and determinants of T2DM in a group of overweight and obese AA with T2DM.

Our study aimed to evaluate total plasma ghrelin (TGh) concentration and its correlation with leptin and insulin in obese African American (AA) adolescents with a family history of type 2 diabetes.Insulin, leptin, and TGh were measured for 15 non-obese controls in fasted state and 19 obese AA adolescents on samples collected during oral glucose tolerance test (OGTT) using radioimmunoassay kits. The hormonal concentrations were compared at fasting levels between obese and non-obese AA adolescents. Insulin, leptin, and TGh concentrations were also compared during OGTT in the obese group.Fasting TGh was significantly lower in obese AA adolescents compared to non-obese controls, while fasting leptin and insulin were significantly higher in obese AA adolescents compared to non-obese controls. During OGTT, for the obese group, TGh increased significantly and plasma leptin decreased significantly. A significant negative correlation was found between TGh and leptin at 30 and 120 min, but at no other time points (0, 60, and 90 min). A significant positive correlation was found between TGh and insulin at 30 min during OGTT, but no other time points.TGh was lower in obese AA adolescents with a family history of type 2 diabetes and a significant correlation occurred between TGh and leptin and TGh and insulin during OGGT at specific time points in our obese group. These findings indicate that insulin resistant obese AA adolescents have impaired ghrelin suppression.

Objective The study aim determined if low 25-hydroxy vitamin D levels correlated with low levels of adiponectin and insulin resistance in African American adolescents with body mass index > or = 85th %. Patients and methods Fasting blood levels of adiponectin, 25-hydroxy vitamin D, insulin, glucose, lipid, leptin and glycosylated hemoglobin were measured in a total of 34 (19 study and 15 control) African American adolescents between the ages of 10 and 20 years. Nutritional vitamin D intake and body composition measurements were assessed. Insulin resistance was calculated using the homeostasis model assessment. Results Adiponectin, fasting insulin, glucose, leptin, triglycerides, HDL, and 25-hydroxy vitamin D levels all reached statistical significance in the group with body mass index > or = 85th percentile when compared to the control population. There was no difference in vitamin D intake between the two groups. Conclusions Low vitamin D levels correlated with low adiponectin levels and obesity and insulin resistance.

Studies were undertaken to evaluate the modulatory effect of maintenance hemodialysis on ouabain sensitive (OS) and ouabain insensitive (OIS) 22 Na + uptake in erythrocytes (E) of 8 chronic renal failure patients of both sexes. Following the receipt of informed consent, the blood samples were obtained just before and after Dialysis. The % 22 Na + uptake of the total 22 Na + present in the assay media was determined in the purified E just before and after Dialysis. The assay medium was composed of 100 mM NaCl, 5 mM KCl, 10 mM trisbase, 10 mM MOPS, 10 mM D-glucose and 60 mM sucrose, pH 7.4 with and without ouabain. Five different concentrations of E, ranging from 0.75 to 2.00 × 10 9 /mL were used for this study. We observed a linear relationship between the 22 Na + uptake and E concentrations in both of the assay systems (OS and OIS). The mean total 22 Na + uptake per 6.5 × 10 9 E/mL in OS and OIS before and after hemodialysis were 3.28 ± 0.4 (OS) and 3.26 ± 0.42 (OIS), and 3.42 ± 0.54 (OS) and 3.42 ± 0.68 (OIS) respectively. The relative % differences between pre- and post-Dialysis were 4 and 5%, which were statistically not significant. From this study, we conclude that hemodialysis does not affect E membrane properties influencing 22 Na + transport.

Contents: Structure and characteristics of erythrocyte insulin receptor. Red blood cell age and insulin receptors. Insulin receptors in human disease states. Obesity. Chronic renal failure. Acanthosis nigricans. Miscellaneous disease states. Insulin receptors in children. Insulin receptors in women during pregnancy. Insulin binding and other hormones. Comparison of biosynthetic insulin, pancreatic human insulin and porcine insulin binding to erythrocytes. Effect of exercise on insulin binding to red blood cells of normal human volunteers. Miscellaneous insulin binding studies. Insulin internalization and degradation. Insulin and erythrocyte metabolism. Summary and conclusion.

In order to establish a standard for sodium influx in erythrocytes for the black population, 22Na+ uptake was measured in 29 normotensive black volunteers. Nineteen males and 10 females during the follicular phase of the menstrual cycle were studied utilizing the procedure of Gambhir el al. (1). In the males, cell concentrations ranging from 0.64 to 2.0 × 109 /ml showed an influx of 0.42 to 1.34% of the total 22Na+ added, and in the females, using the same erythrocyte concentrations, the 22Na+ influx ranged from 0.37 to 1.1%; these differences were not significant. Intraassay variation of the 22Na+ data was 4.8%. Interassay variations have been explained elsewhere (1). These data provided a range of observed values for 22Na+ uptake in erythrocytes from a subpopulation of normotensive black males and females for comparison with hypertensive patients.

Human serum albumin was labeled with N-bromoacetyl-l-tryptophan (attached at the 3 position of a histidyl residue), pyridoxal 5'-phosphate (attached to the e-amino group of lysyl residues) and 1-dimethylaminonaphthalene-5-sulfonyl chloride (attached to e-lysyl and tyrosyl-OH residues). Binding studies with these preparations were conducted with N-acetyl-l-tryptophan to determine the extent of blockage of the indole binding site by these reagents. At labeling conditions of 1:1 molar ratio of labeling agents to albumin, 25 to 65% blockage of the indole binding site occurred. When labeling was conducted in the presence of indolepropionate, the labeling was much reduced at the indole binding site, confirming the specificity of the labeling agents. Following the procedures used by McMenamy, Dintzis, and Watson for unlabeled human serum albumin ((1971) J. Biol. Chem. 246, 4744) CNBr fragmentation of the labeled albumins was conducted and the three major fragments were isolated. Sixty-five per cent or more of the attached labels in each preparation were found in Fragment C (mol wt, ∼18,000). At least one of the labeled positions in this fragment (but not all) was effective in blocking the indole binding site. A tyrosyl-OH group, which was located in Fragment A (mol wt, ∼33,000) and which reacted to a limited extent with 1-dimethylaminonaphthalene-5-sulfonyl chloride also influenced binding at the indole site. The diversity of the labeling agents, the diversity of the groups to which the labels were attached, and other physical-chemical considerations lead to the conclusion that the site is very flexible and adaptable. The evidence supports the positioning of the indole binding site between Fragments A and C as they exist in whole albumin. The dominance of the labeling positions in Fragment C also leads to the conclusion that this fragment is the major locus for ligand binding in albumin.

Glucose tolerance does not improve to the normal level after dialysis; however, our studies showed that the insulin receptor binding to erythrocytes of nondiabetic patients with chronic renal failure (CRF) on hemodialysis was more than that in normal subjects. To understand this apparent anomaly in insulin receptor action and glucose metabolism, we investigated insulin degradation-a postreceptor event of insulin binding-in erythrocytes from CRF patients and compared it with that of normal subjects. We studied insulin degradation by erythrocytes from each of eight CRF patients and five normal subjects. The average hyperbolic insulin degradation curve for the CRF patients showed lower activity and a right-handed shift compared to the curve for the normal subjects. The average maximum degradation of insulin in the CRF patients was significantly lower than that of normal subjects. The number of erythrocytes required to produce 50% of maximum insulin degradation was significantly greater in these patients than that in the normal subjects. Furthermore, a linear correlation was observed between the duration of dialysis and maximum percent of insulin degradation in the CRF patients. Clinical implications of these findings are unclear at the present time. However, the insulin-degrading activity in erythrocytes may be reflective of that in other body tissues.

Chronic renal failure is associated with altered insulin sensitivity of unclear etiology. To investigate the effect of renal failure on insulin binding, we studied insulin binding in mature erythrocytes from 5 undialyzed and 12 chronically dialyzed patients with renal failure. The cell suspension of the isolated and purified human erythrocytes (3.52 × 109/ml) was incubated with 100 pg of 125I-insulin and a range of unlabeled insulin concentrations (pH 8.0, 15°C for 3.5 h). A maximum of 7.9 ± 1.6 and 14.1 ± 3.5 (mean ± SD) specific percent of 125I-insulin was bound by the undialyzed and dialyzed patients respectively, as compared to 10.1 ± 1.4 (mean ± SD) maximum specific percent of insulin bound by the normal subjects. Scatchard plots from the normal, undialyzed and dialyzed subjects were curvilinear, indicating negatively cooperative insulin receptor site-site interactions. From the DeMeyts1 analyses of the Scatchard plots, it was determined that the unoccupied receptor site affinity constant, Ke, for the normal subjects was 0.5 × 108 M-1 whereas that for the undialyzed and the dialyzed patients was 0.69 × 108 M-1. The normal subjects had 410 receptor sites per erythrocyte; however, the undialyzed patients had 215 sites per cell and the dialyzed patients had a receptor number similar to that of the normal subjects. The undialyzed patients had 48% fewer receptor sites than the dialyzed patients and the normal subjects. The undialyzed patients comparing with the normal subjects thus, showed a reduction in insulin binding and in the number of receptor sites with increased affinity. Chronic dialysis caused an increase of insulin binding and of receptor number when compared with the undialyzed patients. In the undialyzed patients with renal failure, the defect in receptor number may be associated with a defect in tissue response to insulin. This defect in insulin receptor number was removed with chronic dialysis. Thus, chronic dialysis may improve insulin sensitivity at the cellular level.

Using conventional techniques of ammonium sulfate fractionation and Sephadex gel column chromatography, insulin-degrading enzyme was partially purified from lysate of human erythrocytes. The enzymatic activity was measured by the trichloroacetic acid precipitation method. Compared to trypsin, the enzyme was highly specific for insulin. The apparent molecular weight of the enzyme was 160,000 Da, the optimum pH was the 7.4 to 7.8 range, and the K m value for insulin for the partially purified enzyme was 162 n m . Bacitracin and N -ethylmaleimide were potent inhibitors, while chloroquine, ethylenediaminetetraacetate, antipain, and soybean trypsin inhibitor failed to inhibit the activity of the enzyme. Like most nucleated cells, human erythrocytes not only have the membranal insulin receptors, but also possess the cytosolic specific insulin-degrading enzyme. Insulin internalization and degradation are shown to be due to the receptor and the enzyme acting in concert as in many nucleated cells. Anucleated erythrocytes have both these entities for possible internalization and degradation of insulin.

Highly specific insulin receptors have been identified on human erythrocytes. A modification of the monocyte insulin radioreceptor technique permitted distinct separation of human erythrocytes with their bound insulin from the free insulin. When incubated with 80 pg. per milliliter of 125I-insulin (pH 8.0, 3.5 hours, 15 ° C.), erythrocytes from 17 normal volunteers specifically bound 10 per cent (± 1.450 S.D.) of the total 125I-insulin. Less than 15 per cent of the total 125I-insulin bound was nonspecific. Binding of 125I-insulin to human erythrocytes was dependent on pH and temperature. Less than 5 per cent of the insulin available to the plasma membrane was degraded. Both calcium and magnesium enhanced 125I-insulin binding by 100 per cent but had no synergistic effect when mixed in a 1:1 molar ratio. Scatchard analysis of the binding data resulted in a curvilinear plot with characteristics typical of negative cooperative interactions between receptor sites and with an unoccupied site affinity constant of 0.1 × 108 M-1. Human erythrocytes have 2,000 insulin binding sites per erythrocyte with 14 sites per square micrometer of surface area. The readily available human erythrocyte, thus, has both specific insulin binding sites and binding characteristics similar to other human cell types. These studies have provided the basis for further clinical investigation of polypeptide hormone receptors on human erythrocytes.

In the cytosol fraction in rat testis seminiferous tubules a lower molecular weight protein of ∼4,800 daltons that binds retinol with high specificity has been isolated and purified by ammonium sulfate precipitation and on Sephadex column chromatography. The hexane extract of the component gave a characteristic retinol fluorescence spectrum. The amino acid composition was qualitatively similar to the retinol binding protein in the blood with the exception that cystine and cysteine were absent.