Osama E. Amer

Irisin as a predictor of glucose metabolism in children: sexually dimorphic effects

Irisin, a novel myokine, increases energy expenditure and glucose tolerance and, thus, improves carbohydrate homeostasis in humans. This hormone has potential therapeutic applications for weight loss and improvement in insulin resistance in subjects with obesity and diabetes mellitus type 2 (T2DM). In this cross‐sectional study, we aimed to associate circulating levels of irisin and several anthropometric and metabolic parameters among Arab children.

Fenugreek extract as an inducer of cellular death via autophagy in human T lymphoma Jurkat cells

BackgroundDrugs used both in classical chemotherapy and the more recent targeted therapy do not have cancer cell specificity and, hence, cause severe systemic side effects. Tumors also develop resistance to such drugs due to heterogeneity of cell types and clonal selection. Several traditional dietary ingredients from plants, on the other hand, have been shown to act on multiple targets/pathways, and may overcome drug resistance. The dietary agents are safe and readily available. However, application of plant components for cancer treatment/prevention requires better understanding of anticancer functions and elucidation of their mechanisms of action. The current study focuses on the anticancer properties of fenugreek, a herb with proven anti-diabetic, antitumor and immune-stimulating functions.MethodJurkat cells were incubated with 30 to 1500 μg/mL concentrations of 50% ethanolic extract of dry fenugreek seeds and were followed for changes in viability (trypan blue assay), morphology (microscopic examination) and autophagic marker LC3 transcript level (RT-PCR).ResultsIncubation of Jurkat cells with fenugreek extract at concentrations ranging from 30 to 1500 μg/mL for up to 3 days resulted in cell death in a dose- and time-dependent manner. Jurkat cell death was preceded by the appearance of multiple large vacuoles, which coincided with transcriptional up-regulation of LC3. GC-MS analysis of fenugreek extract indicated the presence of several compounds with anticancer properties, including gingerol (4.82%), cedrene (2.91%), zingerone (16.5%), vanillin (1.52%) and eugenol (1.25%).ConclusionsDistinct morphological changes involving appearance of large vacuoles, membrane disintegration and increased expression of LC3 transcripts indicated that fenugreek extract induced autophagy and autophagy-associated death of Jurkat cells. In addition to the already known apoptotic activation, induction of autophagy may be an additional mechanism underlying the anticancer properties of fenugreek. This is the first report showing fenugreek as an inducer of autophagy in human cells and further work is needed to define the various intermediates of the autophagic pathway.

Does visceral adiposity index signify early metabolic risk in children and adolescents?: Association with insulin resistance, adipokines, and subclinical inflammation

Background:Visceral adiposity index (VAI) is a novel gender-specific index based on waist circumference (WC), BMI, and lipid parameters. Although VAI does not actually estimate visceral adiposity, it accurately reflects visceral fat function and insulin resistance. This index has not been studied in children thus far. This study aims to fill this gap.Methods:In a cohort of Saudi children and adolescents, anthropometric measurements and metabolic/hormonal profile were obtained.Results:A total of 543 subjects, 292 of whom were boys, were included (mean age: 11.9 ± 3.3 y; BMI: 19.8 ± 5.6 kg/m2). In all subjects, VAI was inferior to BMI and WC regarding its correlations with adiponectin, leptin, insulin resistance (homeostasis model of assessment–insulin resistance (HOMA-IR)), C-reactive protein (CRP) level, and systolic blood pressure, but it exhibited a stronger association with glucose in boys (r = 0.23; P < 0.01). In stepwise multivariate analyses, only BMI was consistent as an independent predictor of adiponectin, leptin, HOMA-IR, and CRP. VAI was the only index independently associated with glucose.Conclusion:Although VAI is related to glucose in children, it seems to be inferior to BMI in terms of association with insulin resistance, adipokines, and subclinical inflammation. Until specific studies can be performed in children, VAI should be extrapolated with caution in this age range.

Habitual Physical Activity is Associated with Circulating Irisin in Healthy Controls but not in Subjects with Diabetes Mellitus Type 2

Irisin, a novel myokine, has been shown to increase following vigorous exercise, with studies suggesting that it mediates some of the beneficial effects of exercise. Irisin might play a role in ‘browning’ of white adipocytes, thus increasing energy expenditure. The role of irisin in exercise and energy expenditure in subjects with diabetes mellitus type 2 (DMT2) remains largely unknown. We aimed to investigate the association between circulating irisin and habitual physical activity in subjects with and without DMT2.

Maternal inheritance of circulating irisin in humans

The recently discovered myokine irisin has been implicated in several observational studies as a potential therapeutic target for obesity-related diseases. However, no information is available as to the heritability of this hormone. The present study aims to fill this gap. A total of 120 families (n=254; 121 adults and 133 children) were included in the study taken from the Riyadh Biomarkers Research Program cohort. Information gathered include anthropometrics, and glycaemic, lipid and adipocytokine profiles. Irisin was measured using ELISA. Examining heritability between mother and offspring, the most significant heritable traits in sons included irisin (P=1.6×10(-5)), systolic blood pressure (P=3.6×10(-4)), total cholesterol (P=3.5×10(-7)) and LDL (low-density lipoprotein)-cholesterol (P=1.2×10(-6)). Heritable traits between mother and daughter again included irisin (P<0.002), as well as anthropometric associations such as waist (P<0.01) and hip (P<0.005) circumference and blood pressure (P<0.002); biochemically, principal associations were observed with HDL (high-density lipoprotein)-cholesterol (P<0.04) and TNF-α (tumour necrosis factor-α) (P<0.002). HDL-cholesterol was the single most significant predictor for irisin levels in adults, explaining 17% of the variance, whereas in children AngII (angiotensin II) was the most significant predictor of irisin levels, explaining 19% of the variance (P=0.003). Circulating irisin appears to be maternally inherited and is predicted by HDL-cholesterol in adults and AngII in children, both factors influenced by energy expenditure and regulation. Taken together, these findings suggest a significant role of irisin in energy-generating processes.

Non liquid nitrogen-based-method for isolation of DNA from filamentous fungi

A simple, efficient, reliable and cost-effective method for isolation of total genomic DNA from fungi, suitable for polymerase chain reaction (PCR) amplification and other molecular applications was described. The main advantages of the method are: (1) does not require the use of liquid nitrogen for preparation of fungi DNA; (2) the mycelium is directly recovered from Petri-dish cultures; (3) the quality and quantity of DNA obtained are suitable for molecular assays; (4) the technique is rapid and relatively easy to perform; (5) it can be applied to filamentous fungi from soil as well as from a fungi from other environmental sources; and (6) it does not require the use of expensive and specialized equipment or hazardous reagents. This method does not require liquid nitrogen for fixation, grinding or storage at - 80°C, making it advantageous over other common protocols. Key words: Genomic DNA extraction, filamentous fungi, polymerase chain reaction (PCR) amplification.

Novel splicing variants of recepteur d'origine nantais (RON) tyrosine kinase involving exons 15–19 in lung cancer

BACKGROUND Altered expressions of receptor tyrosine kinases drive the growth and metastasis of several cancers. RON is a single pass transmembrane receptor tyrosine kinase (RTK) shown to be aberrantly expressed in various cancer types. However, target validation and successful therapeutic targeting of RON in cancers is hampered by the co-existence of unknown number/types of isoforms, which are structurally similar but functionally diverse. OBJECTIVE The objective of this study was to identify differential splicing in the C-terminal region of RON transcripts to better understand RON signaling in cancers. mRNA transcript sequence between exons 14 and 20 of RON was PCR amplified and sequenced using cDNA from 10 SCLC and 13 NSCLC cell lines. Specific exon deletions were identified by aligning sequencing chromatograms with reference RON cDNA sequence. RESULTS We identified the presence of four unique transcript sequence variants of RON formed through skipping of exons 15-19, 16-19, 16-17 and 16. The transcript variants, except the one lacking exons 15-19, were found in more than one cell line. Several cell lines contained two to four of these uniquely spliced transcript variants. dbEST (Expressed Sequence Tags database) or other DNA sequence databases did not contain RON cDNA sequences corresponding to any of the above exon deletions indicating that all these transcript sequence alterations are novel. CONCLUSIONS Results of our study indicate common occurrence of different types of alternatively spliced transcripts of RON in lung cancer with potential to be translated into proteins lacking active kinase domain. Our findings suggest that tumors produce several dominant negative isoforms which probably inhibit ligand dependent RON signaling, and hence, raise important questions regarding the appropriateness of blocking wild type RON signaling for therapy. Further, presence of transcript variants and their isoform products may interfere with quantitative and functional analysis during target validation.

SNPs in FNDC5 (irisin) are associated with obesity and modulation of glucose and lipid metabolism in Saudi subjects

BackgroundIrisin is a recently identified myokine that plays an important role in preventing obesity and insulin resistance. We investigated whether the common FNDC5 (irisin precursor) gene variants influence susceptibility to obesity and type 2 diabetes (T2D) and verified the impact of FNDC5 gene variants on serum irisin levels, glucose and lipid metabolism in a Saudi population.MethodsGenomic DNA from 814 (394 T2DM and 414 controls) subjects were genotyped for the five common SNPs (rs3480A/G, rs1746661G/T, rs1298190A/G, rs726344A/G and rs1570569G/T) of the FNDC5 gene using the TaqMan genotyping assay. Biochemical parameters and hematic concentrations of irisin and insulin as well as anthropometric indices were collected.ResultsSerum irisin levels were higher in T2DM patients compared to controls (p < 0.0001). Analyses of FNDC5 SNPs showed that: 1) The rs3480 GG associates with decreased risk of obesity (p = 0.005; odds ratio: 0.48) and lower body mass index (BMI) values (p = 0.03). In addition, GGAAG was identified as the protective haplotype against risk of obesity (p = 0.001; odds ratio: 0.23). 2) The rs1746661 G allele associates with higher triglyceride (TG) levels (p = 0.019). 3) The rs157069 TT genotype associates with higher fasting insulin (p = 0.029) and HOMA-IR (p = 0.002) as well as with lower circulating irisin levels (p = 0.016).ConclusionsSNPs in FNDC5 gene correlates with obesity and glucose-lipid metabolism possibly because they modulate the serum levels of irisin.

Circulating betatrophin in healthy control and type 2 diabetic subjects and its association with metabolic parameters

AIMS Betatrophin, a newly identified liver and adipose tissue-derived hormone, has been suggested as an inducer of β-cell proliferation in mice. However, the physiological role of betatrophin remains poorly understood in humans. Hence, the aim of this study was to investigate circulating betatrophin concentrations in normal and type 2 diabetes mellitus (T2DM) Saudi subjects and its association with various metabolic parameters. METHODS In this cross-sectional study, 200 Saudi adults (81 healthy non-T2DM controls, age: 41.43±8.35 [mean±SD]; BMI: 31.58±5.49 and 119 T2DM subjects, age: 48.78±11.76years; BMI: 30.25±4.83kg/m(2)) were studied. Anthropometric and fasting serum biochemical data were collected. Circulating betatrophin was measured using an enzyme-linked immunosorbent assay (ELISA) based kit. RESULTS We observed significantly higher levels of betatrophin in T2DM subjects compared to healthy controls (882.19±329.06 vs 657.14±261.04pg/ml, p<0.001). Furthermore, in T2DM subjects, betatrophin level was positively associated with blood pressure and serum fasting glucose (p<0.05). CONCLUSIONS Our results suggest that circulating betatrophin is significantly elevated in subjects with T2DM compared to healthy controls. Increase in the level of betatrophin in T2DM subjects might be a compensatory mechanism for enhanced insulin demand in T2DM condition.

Inflammation as a contributing factor among postmenopausal Saudi women with osteoporosis.

Abstract Postmenopausal osteoporosis is an important metabolic bone disease characterized by rapid bone loss occurring in the postmenopausal period. Recently, the most prevalent form of clinically significant osteopenia and osteoporosis involves various inflammatory conditions. The aim of the study is to evaluate the association between proinflammatory markers (interleukin [IL]-1&bgr;, IL-6, TNF-&agr;) with bone turnover markers (BTMs) in postmenopausal Saudi women with and without osteoporosis. A total of 200 postmenopausal Saudi women ≥50 years old, 100 with osteoporosis and 100 without osteoporosis (control) were recruited under the supervision of qualified physicians in King Salman Hospital and King Fahd Medical City, Riyadh, Saudi Arabia. Serum tumor necrosis factor alpha (TNF-&agr;), IL-1, IL-4, IL-6, and parathyroid hormone (PTH) were determined using Luminex xMAP technology. N-telopeptides of collagen type I (NTx) was assessed using ELISA, 25(OH) vitamin D and osteocalcin were determined using electrochemiluminescence, serum calcium and inorganic phosphate (Pi) were measured by a chemical analyzer. Serum IL-1&bgr;, IL-6, NTx, and PTH levels in women with osteoporosis were significantly higher than controls. Although IL-4 and osteocalcin were significantly lower than controls. IL-1&bgr; and TNF-&agr; were positively associated with NTx in osteoporosis women. TNF-&agr;, IL-6, and TNF-&agr; were positively correlated with IL-l&bgr; in both groups. A significant negative correlation between osteocalcin and IL-1&bgr; in healthy women and women with osteoporosis were observed. Findings of the present study implicate a role for cytokine pattern-mediated inflammation in patients with osteoporosis.