Studies on the mechanisms of action and physiological relevance of SOCS proteins

Understanding systemic biological pathways and the key cellular mechanisms that dictate disease states, drug response, and altered cellular function in metabolic disorders is a significant challenge. Research in the last 20 years have made it clear that tissue communication, through the actions of endocrine, paracrine or autocrine factors play a significant role in pathogenesis of complex multiorgan diseases such as the metabolic syndrome. The actions of these factors are governed both at the site of production and through mechanisms that regulate the sensitivity of target tissues. The Suppressors of Cytokine Signaling (SOCS) proteins act as negative regulators of the main cytokine and growth factor signaling pathways in multiple tissues and as such have important physiological functions. The molecular basis for SOCS actions as well as their role in the pathogenesis of metabolic diseases is just starting to be understood. All SOCS proteins (SOCS1 to 7 and CIS) are characterized by the presence of structural motifs called SOCS box and a SH2 domain. SOCS are thought to act as substrate recognition subunits of multimeric Cullin/RING E3 ubiquitin ligase complexes. It has been proposed that the SH2 domain mediates the recognition of tyrosine phosphorylated signaling proteins to be targeted for ubiquitination and subsequently, proteasomal degradation, thereby inhibiting cytokine signaling. In this thesis we investigated the mechanisms of action of SOCS2 and SOCS6 in the inhibition of cellular signaling and the physiological consequence of their actions. We demonstrated that both SOCS2 and SOCS6 assemble a canonical ECS (Elongin/Cullin/SOCS) complex through the interaction of SOCS box with Elongin B and C, cullin 5 and Rbx2. We also demonstrated that SOCS2 and SOCS6 exert E3- ligase activity towards the growth hormone (GH) receptor and cKIT proteins, respectively. Our structural and binding studies confirmed the existence of substrate binding motifs mainly in the SH2 domains and the N-terminal domain of both SOCSs. The C-terminus harbours the cullin 5 recognition domain that controls both E3 ligase activity of the complex as well as the SOCS stability. We proposed that extended target recognition domain in the SOCS proteins may serve to broaden their specificity toward various targets and hence their ability to regulate various signaling pathways. On the other hand, the existence of a degradation signal within the Elongin C interacting domain of SOCS proteins may serve to secure their timely actions avoiding competition from SOCS that are not engaged in active E3 ubiquitin ligase complexes. The patho-physiological role of SOCS2 was studied in SOCS2 knockout (SOCS2-/-) mice. In line with the in vitro studies (paper I), we observed an increased GH sensitivity in SOCS2-/- mice, demonstrated by low plasma GH/IGF1 ratio. In the liver, this enhanced sensitivity was manifested through increased VLDL secretion and reduced hepatic triglycerides levels. SOCS2-/- showed reduced hepatic steatosis upon high fat feeding as compared to wild type littermates but also exhibited increased adiposity and fat deposition in the skeletal muscles accompanied by profound systemic insulin resistance. We also demonstrated the involvement of SOCS2 in the regulation of inflammatory pathways. SOCS2-/- mice showed an exacerbated response to a high fat diet, with increased expression of inflammatory cytokines such as IL-6, RANTES, IL1β both in the liver and adipose tissue. We also identified possible mechanisms to explain these phenomena by demonstrating that macrophages isolated from SOCS2-/- mice showed higher phagocytic activity and higher LPS-induced NF-κB activity; indicative of SOCS2 negative regulation of TLR4 signals. Given the short half-life of SOCS proteins in the cells, the regulation of SOCS gene transcription is an important mechanism to control their function. The nuclear receptor LXR has regulatory functions on hepatic lipid metabolism that overlap with those controlled by the GH. Therefore, in order to understand the molecular basis for possible crosstalks between these two pathways, we studies how LXR ligands regulate the GH receptor signaling in liver. We showed that LXR agonist downregulates STAT5b protein levels and suppresses GH receptor activity in hepatocytes through a mechanism involving SREBP1. The regulation by SREBP1 occurs through the modulation of STAT5b protein stability and results in reduced expression of GH target genes such as SOCS2. These results provide a plausible explanation for the hepatosteatosis observed upon LXR agonist treatment in vivo. In conclusion, through structural, in vivo and in vitro studies, we provide mechanistic and functional data on SOCS2 and SOCS6; information that may lead to a better understanding of the distinct physiological functions of these proteins. Given our demonstration on the key role of ubiquitination on SOCS functions, future mechanistic studies of SOCS2 and SOCS6 function should focus on the identification of ubiquitination targets of these proteins. Are the physiological functions ascribed to these proteins a result of the degradation of a few target proteins or do they have many targets? If the later is the case, how is SOCS target-specificity structurally determined and how is their activity regulated in time and cellular location? The demonstration that SOCS2 regulate both GH receptor and TLR4 signaling offers system where these questions can be addressed. At physiological levels, the SOCS2-/- mice constitute a novel model system for the study of the metabolic syndrome with unique features that are relevant to the human disease. In the SOCS2-/- mice, insulin resistance and production of inflammatory cytokine are exacerbated by high fat feeding and associated with obesity and deposition of triacylglycerides in the muscle. In these conditions reduced accumulation of TG in liver is observed. This model presents opportunities for future investigations aiming to distinguish between steatotic versus inflammatory causes for insulin resistance

Frequencies of the Arg16Gly, Gln27Glu and Thr164Ile Adrenoceptor β2 Polymorphisms among Omanis

Objectives: This study aimed to assess the distribution of missense mutations in the adrenoceptor β2 (ADRB2) gene in an Omani cohort. Methods: This study was carried out between May 2014 and March 2015 at the Sultan Qaboos University, Muscat, Oman. Blood samples were taken from 316 unrelated Omani subjects. Genotyping for rs1042713 (c.46A>G, p.Arg16Gly), rs1042714 (c.79C>G, p.Gln27Glu) and rs1800888 (c.491C>T, p.Thr164Ile) polymorphisms was performed by real-time polymerase chain reaction using single nucleotide polymorphism (SNP) genotyping assays. The allelic frequencies of these polymorphisms were estimated on the basis of the observed numbers of specific alleles from the genotype data for male and female subjects. The genotype frequencies for each polymorphism were tested for deviation from the Hardy-Weinberg equilibrium. Results: Gly16 and Glu27 were the most frequent variants found among the cohort (63% and 75%, respectively). The Ile164 variant was not detected in the study population. There was a significant linkage disequilibrium between the rs1042713 and rs1042714 SNPs (r2 = 0.209; P ≤0.001). The most observed haplotypes were Gly16-Gln27 and Arg16-Gln27 (0.37 and 0.38, respectively). The frequency of Gly16-Glu27 was 0.25, comprising all Glu27 carriers. Conclusion: The allelic distribution of variants in this Omani cohort was similar to distributions reported among Caucasian populations

Mechanisms of Inhibition and Contraction in Uterine Smooth Muscle

(1) The possible mechanisms involved in the variation in rat uterine response to adrenoceptor agonists in preparations under different hormonal conditions have been investigated during the natural oestrous cycle and in pregnant and post-partum animals using pharmacological and biochemical techniques. (2) Uterine tone was induced with acetylcholine (Ach) in isolated preparations from non-pregnant and pregnant animals. Tension developed to Ach was more than twofold higher in uteri from 20-day and 1-day post-partum animals than in those from the four phases of the oestrous cycle. The observed variation in uterine response to Ach may reflect changes that occur in the thickness of the myometrium under the different hormonal states. (3) Noradrenaline (NA) , adrenaline (ADR), isoprenaline (ISO) and isoxsuprine (ISOX) produced inhibitory responses in uteri from non-pregnant and pregnant animals. During the oestrous cycle, the effects elicited by NA, ADR and SAL varied with the phase of the cycle. This variation could be partially due to the activation of a -excitatory receptors (NA and ADR) and/or to alterations in agonists removal mechanisms during the oestrous cycle. (4) Pre-treatment of animals with oestradiol- 17B increased the uterine response to SAL when compared to effects observed in natural oestrus indicating a role for the ovarian hormones in regulating adrenoceptor function in this preparation. (5) Inhibition of cyclo-oxygenase activity with flurbiprofen (FBF) enhanced uterine inhibitory response to the adrenoceptor agonists in preparations from nonpregnant, pregnant and post partum animals suggesting that intramurally generated prostaglandins were involved in their response. The effect elicited by FBF was, however, not reversed by excess exogenous arachidonic acid. Inhibition of phospholipase A2 activity with quinacrine also enhanced uterine inhibitory response to the adrenoceptor agonists. (6) Removal of the endometrium slightly reduced uterine response to ADR and SAL with the effects being greater in 1-day post-partum than in 20-day pregnant animals. In endometrium-free preparations, FBF had no significant effect on adrenoceptor agonists responses which would tend to suggest that the endometrium may play a role as a major source of PGs in the interaction between these agonists and the cyclo-oxygenase pathway leading to prostaglandin production. (7) Biochemical measurements of uterine adenosine 3',5' cyclic monophosphate (cAMP) were made in uteri from non-pregnant and pregnant animals. During the oestrous cycle, basal cAMP levels were similar in uteri from the four phases and cyclo-oxygenase inhibition with FBF had no effect on these levels nor on the ability of SAL to increase tissue cAMP content. Thus it would appear that cAMP may not be involved in the variation in uterine response to adrenoceptor agonists during the oestrous cycle. (8) Removal of the endometrium in uteri from 20-day pregnant animals did not alter basal tissue cAMP content neither did it affect the ability of SAL to increase cAMP levels. An effect on tissue cAMP metabolism may, therefore, not account for the observed changes in uterine response to adrenoceptor agonists in endometrium-free preparations. (9) In conclusion, presence of a heterogeneous population of adrenoceptors, an avid agonist removal mechanism, ovarian hormones and intramurally generated prostaglandins appear to contribute to the observed variations in uterine responses to adrenoceptor agonists during the oestrous cycle. cAMP is not the source of the variation. Adrenoceptor agonists effect on intramural prostaglandin production could play an important role in their overall response in the rat uterus since such an interaction was also present in preparations from pregnant and post-partum animals

The investigation of hand woven products and motifs in the Sultanate of Oman in order to rejuvenate a local market

Traditional Bedouin rugs are considered to be one of the most valuable items of cultural heritage throughout the centuries in Oman. The methods for weaving these products and the motifs they employ are full of symbolism and explanations. In the last few decades, the modernization and imported rugs has forced weavers to abandon their craft, as it is not economically viable when forced to compete with the imported rug industry. Additionally, local people seem unable to find rugs, which meet their needs from amongst the locally hand-woven products, and this creates a demand for imports. A solution to this problem is sought in this investigation. The aim of this study is a revival of the original Omani handicrafts that are created by desert people, whose influence was uniquely exercised on the various artistic Islamic decorative motifs. In addition surveys of the local market‟s needs were undertaken to get a better understanding of this industry. The research concludes that an invigoration of the industry is possible; given certain training conditions and marketing effects. An experiment for possible future work was undertaken using computerized „Jacquard loom‟ production, with the aim of establishing soft furnishing textiles industry in Oman. These computerized looms, with their capability to produce different kinds of fabrics and patterns, can introduce traditional or Islamic motifs to soft furnishing fabrics into Oman which is what the local market requires

Computer-aided diagnosis of complications of total hip replacement X-ray images

Hip replacement surgery has experienced a dramatic evolution in recent years supported by the latest developments in many areas of technology and surgical procedures. Unfortunately complications that follow hip replacement surgery remains the most challenging dilemma faced both by the patients and medical experts. The thesis presents a novel approach to segment the prosthesis of a THR surgical process by using an Active Contour Model (ACM) that is initiated via an automatically detected seed point within the enarthrosis region of the prosthesis. The circular area is detected via the use of a Fast, Randomized Circle Detection Algorithm. Experimental results are provided to compare the performance of the proposed ACM based approach to popular thresholding based approaches. Further an approach to automatically detect the Obturator Foramen using an ACM approach is also presented. Based on analysis of how medical experts carry out the detection of loosening and subsidence of a prosthesis and the presence of infections around the prosthesis area, this thesis presents novel computational analysis concepts to identify the key feature points of the prosthesis that are required to detect all of the above three types of complications. Initially key points along the prosthesis boundary are determined by measuring the curvature on the surface of the prosthesis. By traversing the edge pixels, starting from one end of the boundary of a detected prosthesis, the curvature values are determined and effectively used to determine key points of the prosthesis surface and their relative positioning. After the key-points are detected, pixel value gradients across the boundary of the prosthesis are determined along the boundary of the prosthesis to determine the presence of subsidence, loosening and infections. Experimental results and analysis are presented to show that the presence of subsidence is determined by the identification of dark pixels around the convex bend closest to the stem area of the prosthesis and away from it. The presence of loosening is determined by the additional presence of dark regions just outside the two straight line edges of the stem area of the prosthesis. The presence of infections is represented by the determination of dark areas around the tip of the stem of the prosthesis. All three complications are thus determined by a single process where the detailed analysis defer. The experimental results presented show the effectiveness of all proposed approaches which are also compared and validated against the ground truth recorded manually with expert user input

The Development of Government Information Infrastructure: The case of Government Cloud Computing in Oman (13)

This paper investigates the roles of institutional isomorphic mechanism in Information Infrastructure (II) implementation. It explores a type of cloud computing namely; Infrastructure as a Service in the context of its national government implementation in Oman. The research answers the following research question; how institutional isomorphic mechanisms impact the Cloud Computing Implementation? The findings revealed that institutional isomorphic mechanisms played a major role in the implementation of government Cloud Computing project in Oman and in particular the Coercive and mimetic mechanisms. Practical and theoretical implications of the findings are then discussed

EXPERIMENTAL INVESTIGATION ON THE RELATIONSHIP BETWEEN LEAD EXPOSURE AND THYROIDS IN DIABETES

Lead exposure can cause multiple systemic toxicities, particularly affecting the hematopoietic, nervous and renal systems. However, its effects on the thyroid functions are not well elucidated and the published studies are controversial. In addition, although there are several experimental thyroid models, each one of them has its own limitations. Accordingly, in this dissertation, we investigated the possible relationship between lead exposure, thyroid functions and short-term systemic toxicity in two animal models, namely normal (non-diabetic) and diabetic animals. We also investigated the possibility of developing a hormonal thyroid model. In the non-diabetic model, Wistar rats were divided into five groups and treated for five days. The four treatment groups received 1, 25, 50, or 100 mg/ kg of lead acetate trihydrate intraperitoneally (i.p.), respectively. The control group received i.p. injections of distilled water. In the diabetic model, diabetes was induced with an i.p. injection of 60 mg/ kg streptozocin (STZ). Six weeks later, lead exposure experiments started. Here, four groups were studied: a control; and 25, 50 and 100 mg/ kg lead acetate groups. In each model, the measured blood lead levels correlated very well with the administered doses of lead acetate. Treatment of the animals with lead acetate resulted in significant weight loss in both models. Lead exposure caused a dose-related increase in thyroid stimulating hormone (TSH) in non-diabetic and diabetic animals. Although, thyroxine (T4) and triiodothyronine (T3) levels remained within normal range in non-diabetic animals, their levels were reduced in diabetic animals. The highest dose of lead (100 mg/ kg) significantly increased white blood cell counts and caused a significant decrease in the number of platelets in non-diabetic animals. In addition, C-reactive protein levels increased significantly in response to lead exposure in this model. Moreover, there was a significant increase in lactate dehydrogenase (LDH), aspartate aminotransferase, total bilirubin, and urea levels; following lead exposure in non-diabetic animals. In comparison, lead exposure in diabetic animals increased urea levels and caused a significant decrease in creatinine levels in plasma. While the concentrations of malondialdehyde were not affected, glutathione stores were depleted in response to lead exposure in the diabetic animals. In the last stage, we tried to develop a new experimental thyroid model, based on the use of hormones. In this experiment, animals were treated for five days with either thyrotropin-releasing hormone (TRH) or octreotide (OCT) to induce hyperthyroidism or hypothyroidism, respectively. Although there were no effects on T4 and T3 levels, TRH was effective in causing an increase in TSH levels. However, TRH also elevated LDH levels. The use of TRH did not cause any other side effects on the tested parameters, which included weight change, oxidative stress markers and renal and hepatic functions. In comparison, OCT failed to affect TSH, T4 and T3 levels, at the dose and treatment duration that we used. In conclusion, short-term lead exposure in healthy and diabetic animal models affected the functions of the anterior pituitary and thyroid glands, caused oxidative stress, liver and kidneys toxicity and induced systemic inflammation. In addition, we found that TRH has a potential to induce hyperthyroidism in experimental animals

Effectiveness of Nasheed-based Teaching of Islamic Education Subject to Fifth-Grade Female Students and Its Impact on their Achievement and Retention of Learning

هدفت الدراسة إلى الكشف عن فاعلية التدريس بالأناشيد في مادة التربية الإسلامية على التحصيل الدراسي، لطالبات الصف الخامس الأساسي، وبقاء أثر التعلم لديهن. ولتحقيق أهداف الدراسة استخدم المنهج شبه التجريبي، حيث أُعدت المادة العلمية باستخدام الأناشيد التعليمية واختباراً تحصيليا مكونا من 21 سؤالا من نوع الاختيار من متعدد، وبعد التأكد من صدق الأداة وثباتها، طبقت على عينة مكونة من 65 طالبة، من مدرسة أم ورقة الأنصارية للتعليم الأساسي 5-7 بمحافظة مسقط، تم تقسيمهن إلى مجموعتين: تجريبية، وعدد طالبتها 33 طالبة، درست باستخدام الأناشيد، وضابطة وعدد طالبتها 32 طالبة، درست بالطريقة الاعتيادية. أظهرت نتائج الدراسة بعد تطبيق الاختبار البعدي الفوري، وجود فروق دالة إحصائيا عند مستوى 0.05 بين متوسطات درجات المجموعة التجريبية والضابطة، لصالح المجموعة التجريبية. ولقياس بقاء أثر التعلم لدى عينة الدراسة، طبق الاختبار البعدي المؤجل؛ بعد مرور أربعة أسابيع من تطبيق الاختبار البعدي الفوري، فأظهرت النتائج أيضا، وجود فروق دالة إحصائيا بين متوسطات درجات المجموعتين؛ التجريبية والضابطة في الاختبار التحصيلي البعدي المؤجل، لصالح المجموعة التجريبية التي درست بالأناشيد. وفي ضوء النتائج التي خلصت إليها الدراسة، أوصت بعدد من التوصيات أهمها: تطبيق التجربة على شريحة واسعة من طلبة الصف الخامس الأساسي ونظرائهم.The study aimed to reveal the effectiveness of the Nasheed-based teaching of Islamic Education subject to fifth-grade female students and its impact on their achievement and the retention of learning effect among them. The sample of the study consisted of 65 fifth-grade students who were selected from a 5-7 grade school at one of the primary schools in Muscat Governorate. The sample was divided into two groups: an experimental group consisting of 33 female students who were taught using nasheeds (Islamic songs) and a control group of 32 female students who were taught using the traditional teaching method. To measure the differences between the two groups, the researchers created an achievement test that consisted of 21 multi-choice questions. The findings of the study showed statistically significant differences between the mean scores of the two groups (the experimental and control groups) in the immediate achievement post-test and the postponed post-test in favor of the experimental group that was taught using nasheeds. The study offers a number of recommendations that include the application of the experiment to a wider category of fifth-grade students in the area of education