Essential role of CD38 in platelet aggregation through the PKC-mediated internalization and activation

Introduction

CD38 is a multifunctional enzyme with a potent Ca2+ mobilizing effect, cyclic ADP-ribose (cADPR), and nicotinic acid adenine dinucleotide phosphate (NAADP). Here, we aimed to demonstrate the role of CD38 in platelets via protein kinase C (PKC)-mediated internalization and activation.

Methods

Mouse platelets were used in this study. Thrombin, an agonist of platelet function, provoked a prompt and long-lasting increase in intracellular Ca2+ concentration ([Ca2+]i), resulting from an interplay of multifold Ca2+ mobilizing messengers.The signaling pathway was delineated using different inhibitors and techniques such as platelet aggregation assay, intracellular calcium measurements, immunoprecipitation, immunoblotting, and flow cytometry.

Results

We observed a sequential formation of cADPR and NAADP through CD38 activation by PKC of non-muscle myosin heavy chain IIA (MHCIIA), resulting in phospholipase C (PLC) activation in the thrombin-stimulated platelets. These findings reveal that PKC is fundamental in activating CD38 and elicits a physiological response in the murine platelets.

Conclusion

PKC is involved in many signaling pathways. Specifically, PKC is involved in the internalization of CD38 via MHCIIA in CD38+/+ wild-type (WT) and CD38-/- knockout mice (KO). CD38 generates calcium-mobilizing agents that act on specific receptors of the calcium stores. Calcium triggered platelet aggregation while serving as a secondary messenger.

Effect of iron overload on renal functions and oxidative stress in beta thalassemia patients

OBJECTIVES

To check the amount of cellular damage caused by serial transfusions of blood in thalassemia patients.  Methods: A cross-sectional study was conducted in the University of Lahore, Lahore, Pakistan between August 2012 and December 2012. A total of 43 thalassemia patients underwent at least 10 blood transfusions. Comprehensive biochemical analysis of blood was performed to record the levels of creatinine, urea, uric acid, albumin, liver function tests, malondialdehyde (MDA), and ferritin.  Results: Serum creatinine (0.732±0.23mg/dl) and uric acid (6.7±0.94mg/dl, p less than 0.05) were significantly higher in patient groups as compared with the control. Ferritin levels were significantly higher in patients as compared with the control (3103.9±1747.4, p less than 0.05). Hemoglobin levels were observed in controls 14±1.3g/dl and in patients 7.1±1.03g/dl. No clear relationship exists between age and hematological parameters of thalassemic patients. Serum ferritin level is positively related with serum alanine transaminase, aspartate aminotransferase, and alkaline phosphatase and MDA (p less than 0.05).  Conclusion: Serum MDA and serum ferritin of patients (r=0.593, p less than 0.05) reflects that both are crucial parameters estimating the cellular damage in patients suffering from thalassemia.

Urinary N-Acetyl-β-D-Glucosaminidase Excretion in Type – II Diabetes Mellitus

<p>Renal complications develop in about 40% of all type II diabetic patients, characterized by persistent albuminuria, leading towards end stage renal disease. N-acetyl-β-D-Glucosaminidase (NAG) a large protein is released in the tubular lumen after proximaltubular damage thus considered as a tubular injury marker. Its raised levels were observed even in normoalbuminu-rics as the onset of microalbuminuria was considered a late finding. With the <strong><em>objective</em></strong> of comparing urinary NAG between normoalbuminuric and microalbuminuric type II Diabetes Mellitus patients, this study was planned.</p><p><strong>Methods:</strong><strong>  </strong>This comparative cross-sectional study was conducted from January to June 2014 at Shaikh Zayed Hospital Lahore on 86 type-II diabetic patients. Out of known type-II diabetic patients from both genders coming to diabetic clinic for routine checkup, those having duration of diabetes for less than 10 years since its diagnosis made and aged 45 – 65 years, were selected through convenient sampling except those with any comorbidity involving kidneys, pregnancy or history of nephrotoxic drug intake. After taking consent, their spot urine samples were collected. Those having urinary ACR (albumin creatinine ratio in mg/g creatinine) &gt; 300 on dipstick termed ‘macroalbumi-nuria’ were also excluded. The albumin, creatinine and NAG assays were performed in the selected spot urine samples. On the basis of urinary ACR, patients were divided into normoalbuminurics (ACR &lt; 30) as group 1 (n = 42) and microalbuminuric (ACR 30 – 300) as group 2 (n = 44). Urinary NAG level was measured in U/L and also expressed as NAG to creatinine ratio (U/ gram creatinine). Data were analyzed through SPSS (v: 21.0) and described as tables and graphs for age, gender, duration of diabetes and urinary NAG. Five point pictorial comparison of NAG to creatinine ratio in both groups was presented through box plot.</p><p><strong>Results:</strong><strong>  </strong>Out of<strong> </strong>86 subjects, mean age was 50.79 years in group 1 while it was 51.89 years in group 2. Majority subjects presented with disease history of 5 – 8 years, with male predominance (64% n = 55). Mean urinary NAG level was 18.69 U/L in group 1 and 42.36 U/L in group 2 and difference was significant<br /> (p = 0.01). Similarly NAG to creatinine ratio values revealed small sized box-plot in group 1 with lower minimum, maximum, median and interquartile range values as compared to group 2.</p><p><strong>Conclusion:</strong>  Among uncomplicated type-II diabetic patients in the first decade of their illness, the excretion of the urinary enzyme, ‘N-acetyl-β-D-Glucosami-nidase’ was observed. Its levels were lower in normo-albuminurics with less variation as compared to micro-albuminurics.</p>