Thermal Stability of siRNA Modulates Aptamer- conjugated siRNA Inhibition.

Oligonucleotide aptamer-mediated in vivo cell targeting of small interfering RNAs (siRNAs) is emerging as a useful approach to enhance the efficacy and reduce the adverse effects resulting from siRNA-mediated genetic interference. A current main impediment in aptamer-mediated siRNA targeting is that the activity of the siRNA is often compromised when conjugated to an aptamer, often requiring labor intensive and time consuming design and testing of multiple configurations to identify a conjugate in which the siRNA activity has not been significantly reduced. Here, we show that the thermal stability of the siRNA is an important parameter of siRNA activity in its conjugated form, and that siRNAs with lower melting temperature (T(m)) are not or are minimally affected when conjugated to the 3' end of 2'F-pyrimidine-modified aptamers. In addition, the configuration of the aptamer-siRNA conjugate retains activity comparable with the free siRNA duplex when the passenger strand is co-transcribed with the aptamer and 3' overhangs on the passenger strand are removed. The approach described in this paper significantly reduces the time and effort necessary to screening siRNA sequences that retain biological activity upon aptamer conjugation, facilitating the process of identifying candidate aptamer-siRNA conjugates suitable for in vivo testing.Molecular Therapy - Nucleic Acids (2012) 1, e51; doi:10.1038/mtna.2012.41; published online 16 October 2012.

Anaemia and kidney dysfunction in Caribbean type 2 diabetic patients.

BACKGROUND: Anaemia has been shown in previous studies to be a risk factor for cardiovascular disease in diabetic patients with chronic kidney disorder. This study was aimed to assess the prevalence of anaemia and kidney dysfunction in Caribbean type 2 diabetic patients that have been previously shown to have a high prevalence of the metabolic syndrome. METHODS: 155 type 2 diabetic patients and 51 non-diabetic subjects of African origin were studied. Anthropometric parameters were measured and fasting blood samples were collected for glucose, creatinine, glycated hemoglobin and complete blood count. Anaemia was defined as haemoglobin < 12 g/dl (F) or < 13 g/dl (M). Kidney function was assessed using glomerular filtration rate (GFR) as estimated by the four-variable Modification of Diet in Renal Disease (MDRD) study equation. Subjects were considered to have chronic kidney disease when the estimated GFR was < 60 ml/min per 1.73 m2. Comparisons for within- and between-gender, between diabetic and non-diabetic subjects were performed using Student's t-test while chi-square test was employed for categorical variables. RESULTS: The diabetic patients were older than the non-diabetic subjects. While male non-diabetic subjects had significantly higher red blood cell count (RBC), haemoglobin and hematocrit concentrations than non-diabetic female subjects (p < 0.001), the RBC and hematocrit concentrations were similar in male and female diabetic patients. Furthermore, irrespective of gender, diabetic patients had significantly higher prevalence rate of anemia than non-diabetic subjects (p < 0.05). Anaemic diabetes patients had significantly lower GFR (67.1 +/- 3.0 vs. 87.9 +/- 5.4 ml/min per 1.73 m2, p < 0.001) than non-anaemic patients. CONCLUSION: A high prevalence of anaemia was identified in this group of type 2 diabetic patients previously shown to have a high prevalence of the metabolic syndrome. It is therefore recommended that diagnostic laboratories in developing countries and elsewhere should include complete blood count in routine laboratory investigations in the management of diabetic patients.

Anaemia and kidney dysfunction in Caribbean type 2 diabetic patients.

BACKGROUND: Anaemia has been shown in previous studies to be a risk factor for cardiovascular disease in diabetic patients with chronic kidney disorder. This study was aimed to assess the prevalence of anaemia and kidney dysfunction in Caribbean type 2 diabetic patients that have been previously shown to have a high prevalence of the metabolic syndrome. METHODS: 155 type 2 diabetic patients and 51 non-diabetic subjects of African origin were studied. Anthropometric parameters were measured and fasting blood samples were collected for glucose, creatinine, glycated hemoglobin and complete blood count. Anaemia was defined as haemoglobin < 12 g/dl (F) or < 13 g/dl (M). Kidney function was assessed using glomerular filtration rate (GFR) as estimated by the four-variable Modification of Diet in Renal Disease (MDRD) study equation. Subjects were considered to have chronic kidney disease when the estimated GFR was < 60 ml/min per 1.73 m2. Comparisons for within- and between-gender, between diabetic and non-diabetic subjects were performed using Student's t-test while chi-square test was employed for categorical variables. RESULTS: The diabetic patients were older than the non-diabetic subjects. While male non-diabetic subjects had significantly higher red blood cell count (RBC), haemoglobin and hematocrit concentrations than non-diabetic female subjects (p < 0.001), the RBC and hematocrit concentrations were similar in male and female diabetic patients. Furthermore, irrespective of gender, diabetic patients had significantly higher prevalence rate of anemia than non-diabetic subjects (p < 0.05). Anaemic diabetes patients had significantly lower GFR (67.1 +/- 3.0 vs. 87.9 +/- 5.4 ml/min per 1.73 m2, p < 0.001) than non-anaemic patients. CONCLUSION: A high prevalence of anaemia was identified in this group of type 2 diabetic patients previously shown to have a high prevalence of the metabolic syndrome.

Potential biomarkers for dementia in Trinidad and Tobago.

Biomarkers that could possibly discriminate between healthy controls and patients with dementias of the Alzheimer's type (AD) and vascular dementia (VaD) were investigated. The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition TR (DSM IV TR) was used to diagnose for dementia in Trinidad. Healthy seniors greater than 60 years old were controls. All participants were administered the Mini-Mental State Examination (MMSE) and had blood analyzed for levels of C-reactive protein (CRP), total homocysteine (tHcy) and microglial antibodies (MgAb). Plasma tHcy was determined on the Abbot AxSym, serum CRP concentrations were measured using the Tina-Quant sCRP (Latex) high sensitive immunoturbidimetric assay and serum MgAb were examined on frozen rat brain sections. The study was carried out on 29 patients that fulfilled the inclusion criteria and 46 controls. Of the patients 65.5% had AD and 34.5% had VaD. Significant differences were found between the mean MMSE scores of the different types of dementias and controls. MgAb presence as well as tHcy were able to distinguish between controls and dementia of the AD and VaD type, respectively. The MMSE is a good discriminative tool for dementias. Serum MgAbs are a possible biomarker for Alzheimer disease pathology and tHcy is elevated in patients with vascular dementia.