UCP1 expression in human brown adipose tissue is inversely associated with cardiometabolic risk factors.

OBJECTIVE: Brown adipose tissue (BAT) is a therapeutic target for obesity. 18F-Fluorodeoxyglucose positron emission tomography (18F-FDG-PET) is commonly used to quantify human BAT mass and activity. Detectable 18F-FDG uptake by BAT is associated with reduced prevalence of cardiometabolic disease. However, 18F-FDG uptake may not always be a reliable marker of BAT thermogenesis, for example insulin resistance may reduce glucose uptake. Uncoupling protein 1 (UCP1) is the key thermogenic protein in BAT. Therefore, we hypothesized that UCP1 expression may be altered in individuals with cardiometabolic risk factors. METHODS: We quantified UCP1 expression as an alternative marker of thermogenic capacity in BAT and white adipose tissue (WAT) samples (n = 53) and in differentiated brown and white pre-adipocytes (n = 85). RESULTS: UCP1 expression in BAT, but not in WAT or brown/white differentiated pre-adipocytes, was reduced with increasing age, obesity and adverse cardiometabolic risk factors such as fasting glucose, insulin and blood pressure. However, UCP1 expression in BAT was preserved in obese subjects of <40 years of age. To determine if BAT activity was also preserved in vivo, we undertook a case-control study, performing 18F-FDG scanning during mild cold exposure in young (mean age ∼22y) normal weight and obese volunteers. 18F-FDG uptake by BAT and BAT volume were similar between groups, despite increased insulin resistance. CONCLUSION: 18F-FDG uptake by BAT and UCP1 expression are preserved in young obese adults. Older subjects retain precursor cells with the capacity to form new thermogenic adipocytes. These data highlight the therapeutic potential of BAT mass expansion and activation in obesity.

The serotonin transporter sustains human brown adipose tissue thermogenesis.

Activation of brown adipose tissue (BAT) in humans is a strategy to treat obesity and metabolic disease. Here we show that the serotonin transporter (SERT), encoded by SLC6A4, prevents serotonin-mediated suppression of human BAT function. RNA sequencing of human primary brown and white adipocytes shows that SLC6A4 is highly expressed in human, but not murine, brown adipocytes and BAT. Serotonin decreases uncoupled respiration and reduces uncoupling protein 1 via the 5-HT2B receptor. SERT inhibition by the selective serotonin reuptake inhibitor (SSRI) sertraline prevents uptake of extracellular serotonin, thereby potentiating serotonin's suppressive effect on brown adipocytes. Furthermore, we see that sertraline reduces BAT activation in healthy volunteers, and SSRI-treated patients demonstrate no 18F-fluorodeoxyglucose uptake by BAT at room temperature, unlike matched controls. Inhibition of BAT thermogenesis may contribute to SSRI-induced weight gain and metabolic dysfunction, and reducing peripheral serotonin action may be an approach to treat obesity and metabolic disease.

Substantial Metabolic Activity of Human Brown Adipose Tissue during Warm Conditions and Cold-Induced Lipolysis of Local Triglycerides.

Current understanding of in vivo human brown adipose tissue (BAT) physiology is limited by a reliance on positron emission tomography (PET)/computed tomography (CT) scanning, which has measured exogenous glucose and fatty acid uptake but not quantified endogenous substrate utilization by BAT. Six lean, healthy men underwent 18fluorodeoxyglucose-PET/CT scanning to localize BAT so microdialysis catheters could be inserted in supraclavicular BAT under CT guidance and in abdominal subcutaneous white adipose tissue (WAT). Arterial and dialysate samples were collected during warm (∼25°C) and cold exposure (∼17°C), and blood flow was measured by 133xenon washout. During warm conditions, there was increased glucose uptake and lactate release and decreased glycerol release by BAT compared with WAT. Cold exposure increased blood flow, glycerol release, and glucose and glutamate uptake only by BAT. This novel use of microdialysis reveals that human BAT is metabolically active during warm conditions. BAT activation substantially increases local lipolysis but also utilization of other substrates such as glutamate.

Commercially available recombinant sonic hedgehog up-regulates Ptc and modulates the cytokine and chemokine expression of human macrophages: an effect mediated by endotoxin contamination?

The Sonic hedgehog (Shh) signalling pathway plays an important role in developmental patterning and proliferation. Recent evidence suggests that Shh also plays a role in the development of the immune system. Here, we demonstrate that components of the Shh signalling pathway are expressed in human macrophages and that the receptor for Shh, Ptc, is up-regulated by a commercially available recombinant preparation of Shh (CArShh). Further, we report that the addition of CArShh up-regulates the production of IL-6, IL-8, MCP-1, IP-10, MIG and RANTES by macrophages, an effect enhanced by the presence of fetal calf serum in the culture medium. In contrast, TGF-beta, TNF-alpha, IL-1b, IL-12 and IL-10 production were not modulated by CArShh and VEGF was minimally up-regulated even in the presence of serum. The up-regulation of these cytokines and chemokines was abrogated by CD14 inhibition and polymixin B, but not reliably inhibited by the specific Shh pathway inhibitor cyclopamine. These results suggest that, although components of the Shh signalling pathway are expressed in macrophages, the modulation of macrophage cytokine and chemokine effector function seen in response to commercially available rShh results from low levels of endotoxin contained within the CArShh preparations employed to explore the effects of Shh in vitro.

Plasma creatine kinase indicates major amputation or limb preservation in acute lower limb ischemia.

OBJECTIVE: Acutely ischemic limbs are often of uncertain viability. To assist operative management, this study determined prospectively which indicators on admission were the best predictors of major amputation and, conversely, limb preservation. METHODS: Data were collected on admission. Presenting complaint, history, clinical assessment, and blood test results, including creatine kinase (CK), were recorded. Surgical procedures were noted-in particular, the presence or absence of major amputation by death or discharge. The setting was a tertiary vascular referral center in a university teaching hospital. Subjects included all patients referred as emergency cases to the vascular unit over an 18-month period who were admitted for inpatient management with acute lower limb ischemia. The main outcome measure was major amputation. RESULTS: A total of 97 patients with acute ischemia were studied prospectively (51 men and 46 women). Twenty-one patients (21.6%) underwent major amputation. Previous vascular surgery (P = .012), mottling (P = .001), sensory loss (P = .003), motor loss (P = .001), muscle tenderness (P < .001), absent ankle Doppler signals (P = .008), neutrophilia (P = .011), and increased CK (P < .001) were significantly associated with major amputation. If CK was normal, the risk of major amputation was 4.6% (95% confidence interval, 0.0%-9.7%). If CK was increased, the risk was 56.2% (95% CI, 39.1%-73.4%). CONCLUSIONS: Specific clinical findings were significantly associated with major amputation. Of these, only CK had a positive predictive value greater than 50%. Plasma CK can assist operative management of acute lower limb ischemia by quantifying prospectively the risk of major amputation or limb preservation on admission.

"Dirty little secrets"--endotoxin contamination of recombinant proteins.

The identification of Toll-like receptors has revolutionised our understanding of innate immunity. TLR4 transduces the LPS signal and that of a number of structurally and functionally unrelated agonists. However, recent evidence adds to longstanding concerns that endotoxin contamination of bacterially derived recombinant TLR4 agonists is responsible for effects attributed to these molecules. We highlight key factors in differentiating specific agonist effects from those of endotoxin and emphasize why conventional methods of detecting and eliminating LPS may lead to erroneous results. We propose that considerable caution is needed in the investigation of TLR4 agonists, particularly when using proteins produced in a bacterium that also houses the most ideal TLR4 agonist, LPS.

The incidence and importance of bacterial contaminants of cadaveric renal perfusion fluid.

Infections represent a significant risk in the postoperative transplant recipient. The perfusion fluid used to perfuse and preserve the kidneys prior to transplantation represents a potential medium in which organisms can grow. The aim of this study was to determine the incidence and clinical relevance of bacterial contamination of perfusion fluid. A total of 4 centres participated in the study and 269 perfusion fluid samples were taken for microbiological analysis. Organisms were isolated from 38 out of 218 (17.4%) perfusion fluid samples taken prior to allograft implantation and 23 out of 51 (45%) samples taken at procurement. Low virulence organisms predominated although Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli were also isolated. Although infective complications were not seen in the allograft recipients, given the frequency with which contamination occurs and the variation in unit antibiotic protocols, we recommend the routine culturing of perfusion fluid to ensure that any potentially significant organisms are identified and treated appropriately.

The role of vascular endothelial growth factor in the kidney in health and disease.

Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen, angiogenic factor and enhancer of vascular permeability. Expressed in the epithelial cells of the developing glomerulus and tubular epithelium, VEGF plays an important role in the development and maintenance of the early vasculature of the kidney. Here, we review the available literature regarding the expression and function of VEGF both in the developing and healthy adult kidney. Furthermore, we highlight how VEGF expression is altered in the diseased kidney and how this modulated expression may impact on and reflect underlying functional changes occurring during the disease process. As discussed, many controversial issues remain, particularly concerning the role of VEGF in the diseased kidney. That VEGF has been proposed as a potential future therapeutic target for the management of some renal diseases requires first that the precise role of VEGF in the normal kidney and various renal pathologies be further and more clearly defined.

Hip disarticulation--the evolution of a surgical technique.

Introduced in the 18th century, hip disarticulation was considered to be one of the most radical operations performed for trauma or disease of the lower limb. The high morbidity and mortality associated with it ensured that it was a rarely performed procedure. It is fortunate that it remains extremely uncommon to the present day. Since the first successful hip disarticulation was described, a number of important advances have occurred. General medical care has improved dramatically and the development of anaesthesia, analgesics, antibiotics and blood transfusions has resulted in greatly decreased morbidity associated with this dramatic operation. This review on the history of hip disarticulation outlines the surgical evolution of the operation, the indications for its use and the techniques used. It draws on the early experiences and preferred techniques of the surgeons of the 19th century, with some discussion on the methods employed to reduce intraoperative haemorrhage. Further development of techniques in the 20th century is also described together with discussion on the evolution of hindquarter amputation.

Sonic hedgehog signaling modulates activation of and cytokine production by human peripheral CD4+ T cells.

Sonic hedgehog (Shh) is important in the growth and differentiation of a variety of cell types, including the development of T cells in the thymus. This prompted us to investigate whether Shh signaling is a functional component of the physiological response of human mature CD4(+) T cells following Ag recognition. In this study, we demonstrate that Shh and its receptor Patched (Ptc) are expressed on resting and activated human peripheral CD4(+) T cells. In approximately one-half of the randomly selected, anonymous blood donors tested, exposure of anti-CD3/28 Ab-activated CD4(+) T cells to the biologically active N-terminal Shh peptide increased the transcription of ptc, thereby demonstrating that Shh signaling had occurred. Furthermore, the addition of exogenous Shh amplified the production of IL-2, IFN-gamma, and IL-10 by activated CD4(+) T cells. The synthesis of IL-2 and IFN-gamma, but not IL-10, by CD4(+) T cells was down-regulated by the addition of neutralizing anti-Shh Ab. Cell surface expression of CD25 and CD69 on activated T cells was up-regulated by exogenous Shh, whereas in the presence of the neutralizing anti-Shh Ab expression it was reduced. Collectively, our findings demonstrate that Shh-mediated signaling is a physiological component of T cell responses, which acts to modulate CD4(+) T cell effector function.

A comparison of computerised tomography, laparoscopic ultrasound and endoscopic ultrasound in the preoperative staging of oesophago-gastric carcinoma.

INTRODUCTION AND OBJECTIVE: Oesophago-gastric carcinoma is associated with a poor prognosis despite advances in diagnosis and treatment. Accurate preoperative staging of gastro-oesophageal carcinoma is, therefore, essential in order to determine patient selection for potentially curative resection. The aim of this study was to evaluate and compare the role of computerised tomography (CT), laparoscopic ultrasound (LapUS) and endoscopic ultrasound (EUS) in the staging of oesophago-gastric carcinoma. METHODS AND PATIENTS: Thirty-six patients with histologically proven carcinoma of the oesophagus or stomach who were considered fit for surgical resection were identified from a prospectively collected database. All patients underwent spiral CT, LapUS and EUS as part of their preoperative staging investigations. RESULTS from the staging modalities were compared retrospectively with final histopathology where available and to intraoperative findings where the tumour was irresectable. RESULTS: Locally advanced tumours (T3/T4) were accurately identified by CT in 15/16 (94%) and by EUS in 14/16 (88%). LapUS was unable to detect 11 tumours (of which five were T3/T4) because they were above the diaphragm, but in the locally advanced cases where the tumour could be seen the accuracy was 10/12 (83%). EUS was the best modality for assessing early tumours and locoregional nodal involvement with accuracies of 8/13 (62%) and 21/29 (72%), respectively. EUS accuracies rose to 64, 92 and 83% for T1/T2, T3/T4 and N staging with the exclusion of those patients (n=6) in whom strictures prevented full assessment. LapUS had a specificity of 100%, compared to 90% for CT and was more accurate than CT for assessing distant metastases (accuracy of 26/32 (81%) compared to 23/32 (72%) for CT). CONCLUSIONS: Although this study is small it has confirmed that CT, EUS and LapUS act in a complimentary manner to provide the most complete preoperative staging for patients with oesophago-gastric cancer.