Syed Ali Imran

Adipokine Gene Expression in Brain and Pituitary Gland

The brain has been recognized as a prominent site of peptide biosynthesis for more than 30 years, and many neuropeptides are now known to be common to gut and brain. With these precedents in mind it is remarkable that adipose-derived peptides like leptin have attracted minimal attention as brain-derived putative neuromodulators of energy balance. This review outlines the evidence that several adipose-specific genes are also expressed in the central nervous system and pituitary gland. We, and others, confirmed that the genes for leptin, resistin, adiponectin, FIAF (fasting-induced adipose factor) and adiponutrin are expressed and regulated in these tissues. For example, leptin mRNA was readily detectable in human, rat, sheep and pig brain, but not in the mouse. Leptin expression in rat brain and pituitary was regulated through development, by food restriction, and following traumatic brain injury. In contrast, hypothalamic resistin mRNA was unaffected by age or by fasting, but was significantly depleted by food restriction in mouse pituitary gland. Similar results were seen in the ob/ob mouse, and we noted a marked reduction in resistin-positive hypothalamic nerve fibres. Resistin and fiaf mRNA were also upregulated in hypoxic/ischaemic mouse brain. Our studies on the regulation of neuronal adipokines were greatly aided by the availability of clonal hypothalamic neuronal cell lines. One of these, N-1, expresses both rstn and fiaf together with several other neuropeptides and receptors involved in energy homeostasis. Selective silencing of rstn revealed an autocrine/paracrine regulatory system, mediated through socs-3 expression that may influence the feedback effects of insulin and leptin in vivo. A similar convergence of signals in the pituitary gland could also influence anterior pituitary hormone secretion. In conclusion, the evidence is suggestive that brain and pituitary-derived adipokines represent a local regulatory circuit that may fine tune the feedback effects of adipose hormones in the control of energy balance.

KiSS-1 mRNA in adipose tissue is regulated by sex hormones and food intake

Hypothalamic KiSS-1 gene expression is critical for the maintenance of reproductive function, and levels are attenuated by sex hormones and by food restriction, providing a link between fat mass and fertility. We hypothesized that adipose tissue (FAT) would express KiSS-1. KiSS-1 mRNA was quantified in FAT, hypothalamus (HYP) and pituitary gland (PIT) using realtime RT-PCR. FAT KiSS-1 expression was sensitive to sex steroids and to nutritional status. Gonadectomized rats given estradiol (E; females) or testosterone (T; males) revealed striking increases in KiSS-1 mRNA in FAT (E: 8-fold, p<0.01; T: 5-fold, p<0.01). In contrast, HYP KiSS-1 expression was reduced by E/T, whereas PIT expression was reduced by gonadectomy only in females, reversed by E. Food restriction (18 h) increased FAT KiSS-1 mRNA in both sexes (2.5-4.0-fold, p<0.01), but decreased levels in male PIT and female HYP. Conversely, FAT expression was reduced in rats fed a high fat diet (HFD), as well as in obese Zucker rats, whereas PIT expression was increased in Zucker rats (p<0.05) but not by HFD. In contrast HYP KiSS-1 mRNA was elevated by HFD. Experiments in which the arcuate nucleus was damaged by an excitotoxic lesion revealed that hypothalamic KiSS-1 mRNA was significantly reduced, whereas FAT levels were unaffected, suggesting that regulation of KiSS-1 in FAT is independent of the hypothalamus. In conclusion, KiSS-1 expression is differentially regulated by sex hormones, food intake and obesity in FAT, HYP and PIT. Kisspeptins of adipose tissue origin may act as adipokines or as local regulators of adipocyte function.

Traumatic brain injury induces adipokine gene expression in rat brain

UNLABELLED Traumatic brain injury (TBI) induces cachexia and neuroinflammation which profoundly impact patient recovery. Adipokine genes such as leptin (ob), resistin (rstn) and fasting-induced adipose factor (fiaf) are implicated in energy metabolism and body weight control and are also associated with chronic low grade inflammation. Since central rstn and fiaf expression was increased following hypoxic/ischemic brain injury, we hypothesized that these genes would also be induced in the rat brain following TBI. Realtime RT-PCR detected a 2-2.5-fold increase in ob mRNA in the ipsilateral cortex and thalamus 12h following lateral fluid percussion (FP)-induced brain injury. Fiaf mRNA was elevated 5-7.5-fold in cortex, hippocampus and thalamus, and modest increases were also detectable in the contralateral brain. Remarkably, rstn mRNA was elevated in ipsilateral (150-fold) and in contralateral (50-fold) hippocampus. To test whether these changes were part of an inflammatory response to TBI we also examined the effects of an intracerebral injection of lipopolysaccharide (LPS). We determined that central injection of LPS produced some, but not all, of the changes seen after TBI. For example, in contrast to the stimulatory influence of TBI, LPS had no effect on ob expression in any brain region, though fiaf and rstn mRNA levels were significantly elevated in both ipsi- and contralateral cortex. IN CONCLUSION (a) brain-derived adipokines could be involved in the acute pathology of traumatic brain injury partly through modulation of central inflammatory responses, but also via leptin-mediated neuroprotective effects and (b) TBI-induced brain adipokines may induce the metabolic changes observed following neurotrauma.

Anemia is an independent risk for mortality after acute myocardial infarction in patients with and without diabetes

IntroductionAnemia and diabetes are risk factors for short-term mortality following an acute myocardial infarction(AMI). Anemia is more prevalent in patients with diabetes. We performed a retrospective study to assess the impact of the combination of diabetes and anemia on post-myocardial infarction outcomes.MethodsData relating to all consecutive patients hospitalized with AMI was obtained from a population-based disease-specific registry. Patients were divided into 4 groups: diabetes and anemia (group A, n = 716), diabetes and no anemia (group B, n = 1894), no diabetes and anemia (group C, n = 869), and no diabetes and no anemia (group D, n = 3987). Mortality at 30 days and 31 days to 36 months were the main outcome measures.Results30-day mortality was 32.3% in group A, 16.1% in group B, 21.5% in group C, 6.6% in group D (all p < 0.001). 31-day to 36-month mortality was 47.6% in group A, 20.8% in group B, 34.3% in group C, and 10.4% in group D (all p < 0.001). Diabetes and anemia remained independent risk factors for mortality with odds ratios of 1.61 (1.41–1.85, p < 0.001) and 1.59 (1.38–1.85, p < 0.001) respectively at 36 months. Cardiovascular death from 31-days to 36-months was 43.7% of deaths in group A, 54.1% in group B, 47.0% in group C, 50.8% group D (A vs B, p < 0.05).InterpretationPatients with both diabetes and anemia have a significantly higher mortality than those with either diabetes or anemia alone. Cardiovascular death remained the most likely cause of mortality in all groups.

Hypothalamic kiss1 mRNA and kisspeptin immunoreactivity are reduced in a rat model of polycystic ovary syndrome (PCOS).

An intact hypothalamic kiss1/kisspeptin/kiss1r complex is a prerequisite for reproductive competence, and kisspeptin treatment could be a practical therapeutic approach to some problems of infertility. One such disorder is polycystic ovarian syndrome (PCOS), a common cause of infertility affecting more than 100 million women. A rodent model of PCOS is the prepubertal female rat treated for a prolonged period with dihydrotestosterone (DHT), which induces many of the metabolic characteristics of the syndrome. We hypothesized that hypothalamic kiss1 mRNA levels, and kisspeptin immunoreactivity (ir), would be abnormal in these rats. Prepubertal female rats were exposed to DHT for 60 days. Rats were killed in two groups: at 26 and 60 days of DHT exposure. Kiss1 mRNA was quantified in hypothalamus, pituitary, ovary and visceral adipose tissue. Separate groups of rats provided brain tissue for immunohistochemical analysis of kisspeptin-ir. At 26 days of DHT exposure, hypothalamic kiss1 mRNA was severely depleted. In contrast DHT had no effect on pituitary kiss1 expression but it significantly increased levels of kiss1 mRNA in fat (+9-fold; p<0.01) and in ovary (+3-fold; p<0.05). At 60days, kiss1 expression had reverted to normal in hypothalamus and ovary but remained elevated in fat (+4-fold; p<0.05). Immunohistochemical analysis revealed that after 26 days of exposure to DHT, kisspeptin-ir was almost completely absent in the arcuate nucleus and a large depletion in kisspeptin +ve fibers was also seen in the paraventricular nucleus, supraoptic nucleus and in the anteroventral periventricular area. At 60 days, despite restored normal levels of kiss1 mRNA, hypothalamic kisspeptin-ir remained depleted in the treated rats. In summary Kiss1 gene expression is differentially affected in various tissues by chronic exposure to dihydrotestosterone in a rat model of polycystic ovary syndrome. In hypothalamus, specifically, kiss1 mRNA, and levels of kisspeptin immunoreactivity, are significantly reduced. Since these rats exhibit many of the characteristics of polycystic ovary syndrome, we suggest that atypical kiss1 expression may contribute to the multiple tissue abnormalities observed in women with this disorder. However, and of some importance, our data do not appear to be consistent with the elevated levels of LH seen in women with PCOS; i.e. reduced levels of hypothalamic kiss1 mRNA and kisspeptin immunoreactivity observed in DHT-treated rats are unlikely to produce elevated LH secretion.

Valproic Acid and CEBPα-Mediated Regulation of Adipokine Gene Expression in Hypothalamic Neurons and 3T3-L1 Adipocytes

Background/Aims: Valproic acid (VPA) is the drug of choice for treating epilepsy, but has the unwanted effects of inducing weight gain and increasing the risk of developing insulin resistance. The mechanism through which these side effects occur is unknown. VPA inhibits histone deacetylase (HDAC), but also decreases the transcriptional activity of CCAAT enhancer binding protein α (CEBPα). Given the possible association between VPA, CEBPα and adipokine gene regulation, we hypothesized that they would alter the expression of resistin (rstn), fasting-induced adipose factor (fiaf) and suppressor of cytokine signaling-3 (socs-3), genes implicated in the development of leptin and insulin resistance. Methods: We investigated the effects of VPA (1 mM; 24 or 48 h) on gene expression using real-time RT-PCR in 3 distinct models: N-1 hypothalamic neurons, 3T3-L1 adipocytes and male CD-1 mice. Subsequently, cells were treated with 5 nM of the more specific HDAC inhibitor trichostatin A (TSA). CEBPα expression was also modified in N-1 neurons using either RNA interference (RNAi) or an overexpression vector to evaluate its effects on target gene expression. Results: In N-1 neurons, VPA induced significant increases in CEBPα and socs-3, but inhibited rstn and fiaf gene expression. In contrast, TSA induced rstn and socs-3, but inhibited fiaf. VPA also induced the expression of CEBPαin 3T3-L1 adipocytes, but had no effect on other target genes, and TSA suppressed fiaf and socs-3.Subsequently, CEBPα was overexpressed (24 h) or silenced using RNAi (24 and 48 h) in N-1 neurons. The silencing of CEBPα led to significant decreases in rstn mRNA, but increased fiaf and socs-3 expression, whereas its overexpression had the opposite effect. When male CD-1 mice were treated with either a single (100 mg/kg; 24 h), or multiple (200 mg/kg; 72 h) daily injections of VPA, no changes in body weight or gene expression were detected in either hypothalamic or adipose tissues. Conclusions: In summary, these experiments reveal a potentially important role for CEBPα in the regulation of hypothalamic gene expression in N-1 neurons and suggest that it might modulate central energy metabolism. Although VPA also modified hypothalamic gene expression in vitro, it remains to be determined whether it has similar effects in vivo.

Adipokine gene expression in a novel hypothalamic neuronal cell line: resistin-dependent regulation of fasting-induced adipose factor and SOCS-3.

Adipokines such as leptin, resistin, and fasting-induced adipose factor (FIAF) are secreted by adipocytes, but their expression is also detectable in the brain and pituitary. The role of central adipokines remains elusive, but we speculate that they may modulate those hypothalamic signaling pathways that control energy homeostasis. Here we describe experiments to test this in which we exploited a novel hypothalamic neuronal cell line (N-1) that expresses a variety of neuropeptides and receptors that are known to be implicated in appetite regulation. Using real-time RT-PCR, we confirmed that N-1 neurons express resistin (rstn) and fiaf, as well as suppressor of cytokine signaling-3 (socs-3), a feedback inhibitor of leptin signaling. Treating N-1 cells with recombinant resistin (200 ng/ml, 30 min) reduced both fiaf (25%, p < 0.005) and socs-3 (29%, p < 0.005) mRNA levels, and similar reductions in fiaf (40%, p < 0.001) and socs-3 (25%, p < 0.001) resulted following the overexpression of resistin. Conversely, when RNA interference (RNAi) was used to reduce endogenous rstn levels (–60%, p < 0.005), fiaf and socs-3 expression was increased (46 and 65% respectively, p < 0.005). A similar reduction in rstn mRNA was achieved using RNAi in differentiated 3T3-L1 adipocytes, and this manipulation also reduced fiaf and socs-3 expression (–53, –21 and –20% respectively, p < 0.005). In contrast, although RNAi successfully reduced fiaf mRNA by 50% (p < 0.001) in N-1 cells and 40% (p < 0.001) in 3T3-L1 cells, there was no effect on rstn or socs-3 mRNA. These data suggest that resistin exerts a novel autocrine/paracrine control over fiaf and socs-3 expression in both 3T3-L1 adipocytes and N-1 neurons. Such a mechanism could be part of the central feedback system that modulates the effects of adipokines, and other adiposity signals, implicated in hypothalamic energy homeostasis. However, it remains to be determined whether these in vitro results can be translated to the control of adipokine expression in brain and adipose tissue.

Impact of admission serum glucose level on in-hospital outcomes following coronary artery bypass grafting surgery

OBJECTIVE The impact of admission serum glucose (SG) level on outcomes in coronary artery bypass grafting (CABG) surgery is unknown. The present study sought to determine whether elevated admission SG level is associated with adverse outcomes following CABG surgery. METHODS Patients undergoing CABG surgery between January 2000 and December 2005 at a single centre were identified (n=2856). Admission SG levels of less than 9.2 mmol/L and 9.2 mmol/L or greater were chosen to divide patients into two groups based on the 75th percentile of SG distribution. A logistic regression model was generated to determine the impact of admission SG level on a composite outcome of any one or more of in-hospital mortality, stroke, perioperative myocardial infarction, sepsis, deep sternal wound infection, renal failure, requirement for postoperative inotropes and prolonged ventilation. RESULTS In total, 76.3% of patients had an admission SG level of less than 9.2 mmol/L (group A) and 23.7% had an admission SG level of 9.2 mmol/L or greater (group B). Group B patients were more likely to be female, have diabetes, have preoperative renal failure, have an ejection fraction of less than 40%, experience myocardial infarction within 21 days before surgery, and have triple vessel or left main disease (P<0.05). Univariate analysis revealed no difference in in-hospital mortality between group A (2.2%) and group B (3.2%) (P=0.12); however, the composite outcome was more likely to occur in group B (40.8%) versus group A (27.9%) (P=0.0001). After multivariable adjustment, admission SG level of 9.2 mmol/L or greater remained an independent predictor of composite outcome (OR=1.3, 95% CI 1.0 to 1.7, P=0.02, receiver operating characteristic = 78%). CONCLUSION Admission SG level of 9.2 mmol/L or greater is associated with significant morbidity in patients undergoing CABG surgery.

Emerging trends in the diagnosis and treatment of acromegaly in Canada

To evaluate demographic data and quality of care of patients with acromegaly in Canada and their evolution over time and secondly, to evaluate predictors of co‐morbidities and treatment outcomes.

Sellar Masses: An Epidemiological Study

BACKGROUND Sellar masses (SM) are mostly benign growths of pituitary or nonpituitary origin that are increasingly encountered in clinical practice. To date, no comprehensive population-based study has reported the epidemiology of SM from North America. AIM To determine the epidemiology of SM in the province of Nova Scotia, Canada. METHODS Data from all pituitary-related referrals within the province were prospectively collected in interlinked computerized registries starting in November 2005. We conducted a retrospective analysis on all patients with SM seen within the province between November 2005 and December 2013. RESULTS A total of 1107 patients were identified, of which 1005 were alive and residing within the province. The mean age at presentation was 44.6±18 years, with an overall female preponderance (62%) and a population prevalence rate of 0.1%. Of patients with SM, 837 (83%) had pituitary adenomas and 168 (17%) had nonpituitary lesions. The relative prevalence and standardized incidence ratio, respectively, of various SM were: nonfunctioning adenomas (38.4%; 2.34), prolactinomas (34.3%; 2.22), Rathkes cyst (6.5%; 0.5), growth hormone-secreting adenomas (6.5%; 0.3), craniopharyngiomas (4.5%; 0.2), adrenocorticotropic hormone-secreting adenomas (3.8%; 0.2), meningiomas (1.9%), and others (3.9%; 0.21). At presentation, 526 (52.3%) had masses ≥1 cm, 318 (31.6%) at <1 cm, and 11 (1.1%) had functioning pituitary adenomas without discernible tumor, whereas tumor size data were unavailable in 150 (14.9%) patients. The specific pathologies and their most common presenting features were: nonfunctioning adenoma (incidental, headaches, and vision loss), prolactinomas (galactorrhea, menstrual irregularity, and headache), growth hormone-secreting adenomas (enlarging extremities and sweating), adrenocorticotropic hormone-secreting adenoma (easy bruising, muscle wasting, and weight gain) and nonpituitary lesions (incidental, headaches, and vision problems). Secondary hormonal deficiencies were common, ranging from 19.6% to 65.7%; secondary hypogonadism, hypothyroidism, and growth hormone deficiencies constituted the majority of these abnormalities. CONCLUSIONS This is the largest North American study to date to assess the epidemiology of SM in a large stable population. Given their significant prevalence in the general population, more studies are needed to evaluate the natural history of these masses and to help allocate appropriate resources for their management.