C-peptide in diabetes: A player in a dual hormone disorder?

C-peptide, a byproduct of insulin synthesis believed to be biologically inert, is emerging as a multifunctional molecule. C-peptide serves an anti-inflammatory and anti-atherogenic role in type 1 diabetes mellitus (T1DM) and early T2DM. C-peptide protects endothelial cells by activating AMP-activated protein kinase α, thus suppressing the activity of NAD(P)H oxidase activity and reducing reactive oxygen species (ROS) generation. It also prevents apoptosis by regulating hyperglycemia-induced p53 upregulation and mitochondrial adaptor p66shc overactivation, as well as reducing caspase-3 activity and promoting expression of B-cell lymphoma-2. Additionally, C-peptide suppresses platelet-derived growth factor (PDGF)-beta receptor and p44/p42 mitogen-activated protein (MAP) kinase phosphorylation to inhibit vascular smooth muscle cells (VSMC) proliferation. It also diminishes leukocyte adhesion by virtue of its capacity to abolish nuclear factor kappa B (NF-kB) signaling, a major pro-inflammatory cascade. Consequently, it is envisaged that supplementation of C-peptide in T1DM might ameliorate or even prevent end-organ damage. In marked contrast, C-peptide increases monocyte recruitment and migration through phosphoinositide 3-kinase (PI-3 kinase)-mediated pathways, induces lipid accumulation via peroxisome proliferator-activated receptor γ upregulation, and stimulates VSMC proliferation and CD4+ lymphocyte migration through Src-kinase and PI-3K dependent pathways. Thus, it promotes atherosclerosis and microvascular damage in late T2DM. Indeed, C-peptide is now contemplated as a potential biomarker for insulin resistance in T2DM and linked to increased coronary artery disease risk. This shift in the understanding of the pathophysiology of diabetes from being a single hormone deficiency to a dual hormone disorder warrants a careful consideration of the role of C-peptide as a unique molecule with promising diagnostic, prognostic, and therapeutic applications.

Cardiac Magnetic Resonance in Patients with Suspected Tachycardia-Induced Cardiomyopathy: The Impact of Late Gadolinium Enhancement and Epicardial Fat Tissue

Tachycardia-induced cardiomyopathy (TIC) is a reversible subtype of dilated cardiomyopathy (DCM) resulting from sustained supraventricular or ventricular tachycardia and diagnosed by the normalization of left ventricular ejection fraction (LVEF) after stable sinus rhythm restoration. The aim of this study was to determine the contribution of cardiac magnetic resonance (CMR) to the differential diagnosis of TIC and DCM with persistent atrial arrythmias in patients hospitalized for the first time with heart failure (HF) with reduced LVEF of nonischemic origin. A total of 29 patients (age: 58.2 ± 16.9 years; males: 65.5%; average EF: 37.0 ± 9.5%) with persistent atrial tachyarrhythmia and first decompensation of HF without known coronary artery diseases were included in this study. The patients successfully underwent cardioversion and were observed for 30 days. The study population was divided into groups of responders (TIC patients; N = 16), which implies achieving FF > 50% or its increase > 10% in 30 days of TIC, and non-responders (N = 13). The increase in left ventricle (LV) volumes measured using CMR was significantly higher in the non-responder group when compared with the responders (114.8 mL ± 25.1 vs. 68.1 mL ± 10.5, respectively, p < 0.05). Non-responders also demonstrated decreased interventricular septum thickness (9.1 ± 0.8 vs.11.5 ± 1.3, respectively, p < 0.05). Late gadolinium enhancement (LGE) was observed in 12 patients (41.4%). The prevalence of LGE was increased in the non-responder group (25.0% vs. 65.1%, respectively, p = 0.046). Notably, a septal mid-wall LGE pattern was found exclusively in the non-responders. Epicardial adipose tissue thickness was decreased in the non-responder group versus the TIC patients. Conclusion: Patients with TIC were found to have smaller atrial and ventricular dimensions in comparison to patients with DCM. In addition, LGE was more common in DCM patients.

Predictors of tachycardia-induced cardiomyopathy in patients with first-time decompensation of chro­nic heart failure with reduced left ventricular ejection fraction of nonischemic etiology and persistent atrial tachyarrhythmia

Aim    To identify possible predictors of tachycardia-induced cardiomyopathy (TICMP) in patients with newly developed decompensated chronic heart failure (CHF) of nonischemic origin with reduced left ventricular ejection fraction (LV EF) and with persistent atrial tachyarrhythmias. Material and methods    This study included 88 patients with newly developed decompensated CHF of nonischemic origin with reduced LV EF and persistent atrial tachyarrhythmias. Resting 12-lead electrocardiography (EGC) and transthoracic echocardiography (EchoCG) were performed upon admission and following the electrical impulse therapy for all patients. Also, 24-h ECG monitoring was performed to confirm sinus rhythm stability. After recovery of sinus rhythm, outpatient monitoring was performed for three months, including repeated EchoCG to evaluate the dynamics of heart chamber dimensions and LV EF. Results    The patients were divided into two groups based on the increase in LV EF: 68 responders (TICMP patients with a LV EF increase by >10%) and 20 non-responders (patients with an increase in LV EF by <10% during 3 months following the sinus rhythm recovery). According to results of the baseline EchoCG, LV EF did not significantly differ in the two subgroups (TICMP, 40±8.3 %, 18–50 % and non-responders, 38.55±7.9 %, 24–50 %); moreover, the incidence of cases with LV EF <30% did not differ either (9 patients TICMP and 2 non-responders, р=1.0). TICMP patients compared to non-responders, had significantly smaller left atrial dimensions (4.53±1.14 (2–7) cm and 5.68±1.41 (4–8) cm, р=0.034; 80.8±28.9 (27–215) ml and 117.8±41.3 (46–230) ml, р=0.03, respectively) and left ventricular end-systolic volume (ESV) (67.7±33.1 (29–140) ml and 104.5±44.7 (26–172) ml, р=0.02, respectively). The effect of major EchoCG parameters on the probability of TICMP development was assessed by one-factor and multifactor regression analyses with adjustments for age and sex. The probability of TICMP increased with the following baseline EchoCG parameters: end-diastolic volume (EDV) <174 ml [odd ratio (OR), 0.115, 95 % confidence interval (CI): 0.035–0.371], ESV <127 ml [OR, 0.034, 95 % CI: 0.007–0.181], left atrial volume <96 ml [OR, 0.08 , 95 % CI: 0.023–0.274], right ventricular dimension <4 cm [OR, 0.042 , 95 % CI: 0.005–0.389].Conclusion    Among patients with newly developed decompensation of CHF with reduced LV EF of non-ischemic origin and persistent atrial arrhythmias, TICMP was detected in 72 % of patients. The probability of TICMP did not depend on baseline EF and duration of arrhythmias, but increased with the following baseline EchoCG parameters: EDV< 174 ml, ESV< 127 ml, left atrial volume <96 ml, right ventricular dimension <4 cm. The multifactorial analysis showed that a right atrial volume <96 ml is an independent predictor for the development of TICMP.

Nonlinear identification of NMR spin systems by adaptive filtering

In this paper, we present two new methods for identifying NMR spin systems. These methods are based on nonlinear adaptive filtering. The spin system is assumed to be time-invariant with memory. The first method uses a truncated discrete Volterra series to describe the nonlinear relationship between excitation (input) and system response (output). First-, second-, and third-order kernels of this series are estimated employing the least mean square (LMS) algorithm. Three parallel filters can then model the NMR spin system so that its output is no more than simple sum of three convolution products between combinations of the input signal and filters coefficients. It is also shown that the contribution of the Volterra second-order term to the total system response is neglected compared with the contributions of the first- and the third-order terms. In the second identification method, the output signal is related to the input signal through a recursive nonlinear difference equation with constant coefficients. The LMS algorithm is used again to estimate the equation coefficients. The two methods are validated with a simulated NMR system model based on Bloch equations. The results and the performances of these methods are analyzed and compared. It is shown that our methods permit a simple identification of NMR spin systems. The field of applications of this study is promising in the optimization of NMR signal detection, especially in the cases of low signal-to-noise ratios where optimum signal filtering and analysis must be performed.

Clinical importance of pre-morteum blood lymphocytes in cadaver donor tissue typing

We have refined our immunomagnetic bead (IM bead) procedures to isolate pure and viable lymphocyte subpopulation from pre-morteum (PM) blood for cadaver donor HLA typing, preliminary and final crossmatches (XMs). The results of 1220 XMs were compared using T/B lymphocytes isolated either from PM blood or spleen/lymphnode (SPLN) tissue. IM bead technique was used to isolate T/B cells from PM blood and nylon wool column (NWC) technique was used to isolate T/B cells from SPLN. When we compared the outcome of 800 T-cell crossmatches using T cells from PM blood or SPLN of 5 separate cadaver donors, NWC TXMs tended to be more falsenegative for high PRA (> 10%, total 500 XMs) as well as low PRA (< 10%, total 300 XMs) did not reach statistical significance. In contrast, NW BXM (420 B XM) were found to be far more false negative than IM bead BXM regardless of the PRA of the patients. In order to ensure that NWC BXMs were indeed false negative, 23 sera with known anti-DR antibodies were BXMed where antigen-specific B cells were isolated by both the techniques. Our results showed that IM bead BXM identified the DR specificities greater than 90% of the time, the titers of ab specificities were stronger (1:8). In comparison, NWB cell XMs were weak (titers 1:2), and the false negative rate for some ab was as high as 73%. Using IM bead and NWC techniques we compared our turnaround time (TAT) for cadaver donor typing, preliminary and final XMs.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet crossmatches of single-donor platelet concentrates using a latex agglutination assay

A latex agglutination assay was evaluated for the purpose of identifying compatible platelet donors for alloimmunized recipients. Assay reagents were prepared by adsorbing detergent-solubilized, donor-specific platelets to polystyrene latex beads. Semiquantitative results for up to 30 donors can be completed in less than 1 hour. These reagents retained their immunoreactivity for at least 3.5 months. A retrospective study has established the assay's upper limit of compatibility. The prospective study evaluated transfusions to a group of multiply transfused patients. Part I evaluated 143 crossmatched, single-donor platelet transfusions given to 50 patients. In 96 percent of the cases, a positive crossmatch was associated with an unsuccessful transfusion outcome; in 84 percent of the transfusions, a negative crossmatch predicted a satisfactory platelet increment. The overall predictability, sensitivity, and specificity were 87, 62, and 99 percent, respectively. Part II evaluated 105 transfusions given to the 43 patients (of 50) in whom no incidence of fever, sepsis, or bleeding could be documented. A positive crossmatch was 96-percent efficient in predicting an unsuccessful transfusion, whereas a negative crossmatch was associated with an adequate platelet increment following 89 percent of the transfusions. The overall predictability was 91 percent, the sensitivity was 72 percent, and the specificity was 99 percent. Within-run and between-run variations were 6.3 and 6.2 percent, respectively. These results demonstrate that detergent-solubilized platelet antigens, immobilized on latex particles, can be used in a cost-effective crossmatching procedure.