Meal-induced thermogenesis in lean and obese prepubertal children.

The resting metabolic rate (RMR) and the thermic effect of a meal (TEM) were measured in a group of 16 prepubertal (8.8 +/- 0.3 y) obese children (43.6 +/- 9.2 kg) and compared with a group of 10 age-matched (8.6 +/- 0.4 y), normal-weight children (31.0 +/- 6.0 kg). The RMR was higher in the obese than in the control children (4971 +/- 485 vs 4519 +/- 326 kJ/d, P < 0.05); after the RMR was adjusted for the effect of fat-free mass (FFM) the values were not significantly different (4887 +/- 389 vs 4686 +/- 389 kJ/d). The thermic response to a liquid mixed meal, expressed as a percentage of the energy content of the meal, was significantly lower in obese than in control children (4.4 +/- 1.2% vs 5.9 +/- 1.7%, P < 0.05). The blunted TEM shown by the obese children could favor weight gain and suggests that the defect in thermogenesis reported in certain obese adults may have already originated early in life.

Differential regulation of Na-K-ATPase isoform gene expression by T3 during rat brain development.

A fetal rat telencephalon organotypic cell culture system was found to reproduce the developmental pattern of Na-K-adenosinetriphosphatase (ATPase) gene expression observed in vivo [Am. J. Physiol. 258 (Cell Physiol. 27): C1062-C1069, 1990]. We have used this culture system to study the effects of triiodothyronine (T3; 0.003-30 nM) on mRNA abundance and basal transcription rates of Na-K-ATPase isoforms. Steady-state mRNA levels were low at culture day 6 (corresponding to the day of birth) but distinct for each isoform alpha 3 much greater than beta 1 = beta 2 greater than alpha 2 greater than alpha 1. At culture day 6, T3 did not modify mRNA abundance of any isoform. At culture day 12 (corresponding to day 7 postnatal), T3 increased the mRNA level of alpha 2 (4- to 7-fold), beta 2 (4- to 5-fold), alpha 1 (3- to 6-fold), and beta 1 (1.5-fold), whereas alpha 3 mRNA levels remained unchanged. Interestingly, the basal transcription rate for each isoform differed strikingly (alpha 2 greater than alpha 1 much greater than beta 1 = beta 2 greater than alpha 3) but remained stable throughout 12 days of culture and was not regulated by T3. Thus we observed an inverse relationship between rate of transcription and rate of mRNA accumulation for each alpha-isoform, suggesting that alpha 1- and alpha 2-mRNA are turning over rapidly whereas alpha 3-mRNA is turning over slowly. Our data indicate that one of the mechanisms by which T3 selectively controls Na-K-ATPase gene expression during brain development in vitro occurs at the posttranscriptional level.

Effects of beta-blockade on energy metabolism following burns.

The purpose of this study was to compare the effects of propranolol administered either by i.v. infusion or by prolonged oral administration (4 days) during the first 3 weeks following burns. The resting metabolic rate (RMR) of 10 non-infected fasting burned patients (TBSA: 28 per cent, range 18-37 per cent) was determined four times consecutively by indirect calorimetry (open circuit hood system) following: (1) i.v. physiological saline; (2) i.v. propranolol infusion (2 micrograms/kg/min following a bolus of 80 micrograms/kg); (3) oral propranolol (40 mg q.i.d. during 4 +/- 1 days); and (4) in control patients. All patients showed large increases in both RMR (144 +/- 2 per cent of reference values) and in urinary catecholamine excretion (three to four times as compared to control values). The infusion of propranolol induced a significant decrease in RMR to 135 +/- 2 per cent and oral propranolol to 129 +/- 3 per cent of reference values. A decrease in lipid oxidation but no change in carbohydrate and protein oxidation were observed during propranolol administration. It is concluded that the decrease in RMR induced by propranolol was not influenced by the route of administration. The magnitude of the decrease in energy expenditure suggests that beta-adrenergic hyperactivity represents only one of the mediators of the hypermetabolic response to burn injury.

Is our heart a well-designed pump? The heart along animal evolution.

A carrier system for gases and nutrients became mandatory when primitive animals grew larger and developed different organs. The first circulatory systems are peristaltic tubes pushing slowly the haemolymph into an open vascular tree without capillaries (worms). Arthropods developed contractile bulges on the abdominal aorta assisted by accessory hearts for wings or legs and by abdominal respiratory motions. Two-chamber heart (atrium and ventricle) appeared among mollusks. Vertebrates have a multi-chamber heart and a closed circulation with capillaries. Their heart has two chambers in fishes, three chambers (two atria and one ventricle) in amphibians and reptiles, and four chambers in birds and mammals. The ventricle of reptiles is partially divided in two cavities by an interventricular septum, leaving only a communication of variable size leading to a variable shunt. Blood pressure increases progressively from 15 mmHg (worms) to 170/70 mmHg (birds) according to the increase in metabolic rate. When systemic pressure exceeds 50 mmHg, a lower pressure system appears for the circulation through gills or lungs in order to improve gas exchange. A four-chamber heart allows a complete separation of systemic and pulmonary circuits. This review describes the circulatory pumping systems used in the different classes of animals, their advantages and failures, and the way they have been modified with evolution.

Characterization of cerebral glucose dynamics in vivo with a four-state conformational model of transport at the blood-brain barrier.

Determination of brain glucose transport kinetics in vivo at steady-state typically does not allow distinguishing apparent maximum transport rate (T(max)) from cerebral consumption rate. Using a four-state conformational model of glucose transport, we show that simultaneous dynamic measurement of brain and plasma glucose concentrations provide enough information for independent and reliable determination of the two rates. In addition, although dynamic glucose homeostasis can be described with a reversible Michaelis-Menten model, which is implicit to the large iso-inhibition constant (K(ii)) relative to physiological brain glucose content, we found that the apparent affinity constant (K(t)) was better determined with the four-state conformational model of glucose transport than with any of the other models tested. Furthermore, we confirmed the utility of the present method to determine glucose transport and consumption by analysing the modulation of both glucose transport and consumption by anaesthesia conditions that modify cerebral activity. In particular, deep thiopental anaesthesia caused a significant reduction of both T(max) and cerebral metabolic rate for glucose consumption. In conclusion, dynamic measurement of brain glucose in vivo in function of plasma glucose allows robust determination of both glucose uptake and consumption kinetics.

Total and exogenous carbohydrate oxidation in obese prepubertal children.

The aim was to explore whether the origin of carbohydrate oxidation (exogenous compared with endogenous carbohydrate) after consumption of a mixed meal was influenced by obesity in children. Ten obese prepubertal children 8 y of age (44.2 +/- 3.6 kg) were studied over 9.5 h and compared with eight normal-weight, matched control children (28.5 +/- 1.6 kg). They were fed a mixed meal containing naturally enriched [13C]carbohydrate (cane sugar and popcorn) providing 55% of the daily energy requirement as measured by 24-h resting metabolic rate. Total carbohydrate oxidation was calculated by indirect calorimetry (hood system) whereas exogenous carbohydrate oxidation was estimated from carbon dioxide production (VCO2), the isotopic enrichment of breath 13CO2, and the abundance of [13C]carbohydrate in the meal ingested. The time course of 13CO2 in breath-measured over 570 min-followed a similar pattern in both groups. Although total carbohydrate oxidation was not significantly different among the two groups, exogenous carbohydrate utilization was significantly greater (P < 0.03) and endogenous carbohydrate oxidation was significantly lower (P < 0.05) in obese compared with control children. In addition, the rate of exogenous carbohydrate oxidation expressed as a proportion of total carbohydrate oxidation was positively related to the body fat of the children (r = 0.68, P < 0.01). The study suggests that in the postprandial phase, a smaller proportion of carbohydrate oxidation is accounted for by glycogen breakdown in obese children. The sparing of endogenous glycogen may result from decreased glycogen turnover already present at an early age.

Histological description of seminiferous epithelium and cycle length of spermatogenesis in the water shrew Neomys fodiens (Mammalia: Soricidae).

Recently, we examined the spermatogenesis cycle length in two shrews species, Sorex araneus characterized by a very high metabolic rate and a polyandric mating system (sperm competition) resulting in a short cycle and Crocidura russula characterized by a much lower metabolic rate and a monogamous mating system showing a longer cycle. In this study, we investigated the spermatogenesis cycle in Neomys fodiens showing an intermediate metabolic rate. We described the stages of seminiferous epithelium according to the spermatid morphology method and we calculated the cycle length of spermatogenesis using incorporation of 5-bromodeoxyuridine into DNA of the germ cells. Twelve males were injected intraperitoneally with 5-bromodeoxyuridine, and the testes were collected. For cycle length determination, we applied a recently developed statistical method. The calculated cycle length is 8.69 days and the total duration of spermatogenesis based on 4.5 cycles is approximately 39.1 days, intermediate between the duration of spermatogenesis of S. araneus (37.6 days) and C. russula (54.5 days) and therefore congruent with both the metabolic rate hypothesis and the sperm competition hypothesis. Relative testes size of 1.4% of body mass indicates a promiscuous mating system.

Mid-gut ACTH-secreting neuroendocrine tumor unmasked with (18)F-dihydroxyphenylalanine-positron emission tomography.

Ectopic ACTH Cushing's syndrome (EAS) is often caused by neuroendocrine tumors (NETs) of lungs, pancreas, thymus, and other less frequent locations. Localizing the source of ACTH can be challenging. A 64-year-old man presented with rapidly progressing fatigue, muscular weakness, and dyspnea. He was in poor condition and showed facial redness, proximal amyotrophy, and bruises. Laboratory disclosed hypokalemia, metabolic alkalosis, and markedly elevated ACTH and cortisol levels. Pituitary was normal on magnetic resonance imaging (MRI), and bilateral inferior petrosal sinus blood sampling with corticotropin-releasing hormone stimulation showed no significant central-to-periphery gradient of ACTH. Head and neck, thoracic and abdominal computerized tomography (CT), MRI, somatostatin receptor scintigraphy (SSRS), and (18)F-deoxyglucose-positron emission tomography (FDG-PET) failed to identify the primary tumor. (18)F-dihydroxyphenylalanine (F-DOPA)-PET/CT unveiled a 20-mm nodule in the jejunum and a metastatic lymph node. Segmental jejunum resection showed two adjacent NETs, measuring 2.0 and 0.5 cm with a peritoneal metastasis. The largest tumor expressed ACTH in 30% of cells. Following surgery, after a transient adrenal insufficiency, ACTH and cortisol levels returned to normal values and remain normal over a follow-up of 26 months. Small mid-gut NETs are difficult to localize on CT or MRI, and require metabolic imaging. Owing to low mitotic activity, NETs are generally poor candidates for FDG-PET, whereas SSRS shows poor sensitivity in EAS due to intrinsically low tumor concentration of type-2 somatostatin receptors (SST2) or to receptor down regulation by excess cortisol. However, F-DOPA-PET, which is related to amine precursor uptake by NETs, has been reported to have high positive predictive value for occult EAS despite low sensitivity, and constitutes a useful alternative to more conventional methods of tumor localization. LEARNING POINTS: Uncontrolled high cortisol levels in EAS can be lethal if untreated.Surgical excision is the keystone of NETs treatment, thus tumor localization is crucial.Most cases of EAS are caused by NETs, which are located mainly in the lungs. However, small gut NETs are elusive to conventional imaging and require metabolic imaging for detection.FDG-PET, based on tumor high metabolic rate, may not detect NETs that have low mitotic activity. SSRS may also fail, due to absent or low concentration of SST2, which may be down regulated by excess cortisol.F-DOPA-PET, based on amine-precursor uptake, can be a useful method to localize the occult source of ACTH in EAS when other methods have failed.

Social huddling and physiological thermoregulation are related to melanism in the nocturnal barn owl.

Endothermic animals vary in their physiological ability to maintain a constant body temperature. Since melanin-based coloration is related to thermoregulation and energy homeostasis, we predict that dark and pale melanic individuals adopt different behaviours to regulate their body temperature. Young animals are particularly sensitive to a decrease in ambient temperature because their physiological system is not yet mature and growth may be traded-off against thermoregulation. To reduce energy loss, offspring huddle during periods of cold weather. We investigated in nestling barn owls (Tyto alba) whether body temperature, oxygen consumption and huddling were associated with melanin-based coloration. Isolated owlets displaying more black feather spots had a lower body temperature and consumed more oxygen than those with fewer black spots. This suggests that highly melanic individuals display a different thermoregulation strategy. This interpretation is also supported by the finding that, at relatively low ambient temperature, owlets displaying more black spots huddled more rapidly and more often than those displaying fewer spots. Assuming that spot number is associated with the ability to thermoregulate not only in Swiss barn owls but also in other Tytonidae, our results could explain geographic variation in the degree of melanism. Indeed, in the northern hemisphere, barn owls and allies are less spotted polewards than close to the equator, and in the northern American continent, barn owls are also less spotted in colder regions. If melanic spots themselves helped thermoregulation, we would have expected the opposite results. We therefore suggest that some melanogenic genes pleiotropically regulate thermoregulatory processes.

Metabolic and respiratory effects of infused sodium acetate in healthy human subjects.

The metabolic and respiratory effects of intravenous 0.5 M sodium acetate (at a rate of 2.5 mmol/min during 120 min) were studied in nine normal human subjects. O2 consumption (VO2) and CO2 production (VCO2) were measured continuously by open-circuit indirect calorimetry. VO2 increased from 251 +/- 9 to 281 +/- 9 ml/min (P < 0.001), energy expenditure increased from 4.95 +/- 0.17 kJ/min baseline to 5.58 +/- 0.16 kJ/min (P < 0.001), and VCO2 decreased nonsignificantly (211 +/- 7 ml/min vs. 202 +/- 7 ml/min, NS). The extrapulmonary CO2 loss (i.e., bicarbonate generation and excretion) was estimated at 48 +/- 5 ml/min. This observation is consistent with 1 mol of bicarbonate generated from 1 mol of acetate metabolized. Alveolar ventilation decreased from 3.5 +/- 0.2 l/min basal to 3.1 +/- 0.2 l/min (P < 0.001). The minute ventilation (VE) to VO2 ratio decreased from 22.9 +/- 1.3 to 17.6 +/- 0.9 l/l (P < 0.005), arterial PO2 decreased from 93.2 +/- 1.9 to 78.7 +/- 1.6 mmHg (P < 0.0001), arterial PCO2 increased from 39.2 +/- 0.7 to 42.1 +/- 1.1 mmHg (P < 0.0001), pH from 7.40 +/- 0.005 to 7.50 +/- 0.007 (P < 0.005), and arterial bicarbonate concentration from 24.2 +/- 0.7 to 32.9 +/- 1.1 (P < 0.0001). These observations indicate that sodium acetate infusion results in substantial extrapulmonary CO2 loss, which leads to a relative decrease of total and alveolar ventilation.

Clustering of cardiovascular risk factors mimicking the human metabolic syndrome X in eNOS null mice.

AIMS/HYPOTHESIS: The metabolic syndrome comprises a clustering of cardiovascular risk factors but the underlying mechanism is not known. Mice with targeted disruption of endothelial nitric oxide synthase (eNOS) are hypertensive and insulin resistant. We wondered, whether eNOS deficiency in mice is associated with a phenotype mimicking the human metabolic syndrome. METHODS AND RESULTS: In addition to arterial pressure and insulin sensitivity (euglycaemic hyperinsulinaemic clamp), we measured the plasma concentration of leptin, insulin, cholesterol, triglycerides, free fatty acids, fibrinogen and uric acid in 10 to 12 week old eNOS-/- and wild type mice. We also assessed glucose tolerance under basal conditions and following a metabolic stress with a high fat diet. As expected eNOS-/- mice were hypertensive and insulin resistant, as evidenced by fasting hyperinsulinaemia and a roughly 30 percent lower steady state glucose infusion rate during the clamp. eNOS-/- mice had a 1.5 to 2-fold elevation of the cholesterol, triglyceride and free fatty acid plasma concentration. Even though body weight was comparable, the leptin plasma level was 30% higher in eNOS-/- than in wild type mice. Finally, uric acid and fibrinogen were elevated in the eNOS-/- mice. Whereas under basal conditions, glucose tolerance was comparable in knock out and control mice, on a high fat diet, knock out mice became significantly more glucose intolerant than control mice. CONCLUSIONS: A single gene defect, eNOS deficiency, causes a clustering of cardiovascular risk factors in young mice. We speculate that defective nitric oxide synthesis could trigger many of the abnormalities making up the metabolic syndrome in humans.

Development of metabolic labeling strategies to study changes in protein expression

Résumé : Les progrès techniques de la spectrométrie de masse (MS) ont contribué au récent développement de la protéomique. Cette technique peut actuellement détecter, identifier et quantifier des milliers de protéines. Toutefois, elle n'est pas encore assez puissante pour fournir une analyse complète des modifications du protéome corrélées à des phénomènes biologiques. Notre objectif était le développement d'une nouvelle stratégie pour la détection spécifique et la quantification des variations du protéome, basée sur la mesure de la synthèse des protéines plutôt que sur celle de la quantité de protéines totale. Pour cela, nous volions associer le marquage pulsé des protéines par des isotopes stables avec une méthode d'acquisition MS basée sur le balayage des ions précurseurs (precursor ion scan, ou PIS), afin de détecter spécifiquement les protéines ayant intégré les isotopes et d'estimer leur abondance par rapport aux protéines non marquées. Une telle approche peut identifier les protéines avec les plus hauts taux de synthèse dans une période de temps donnée, y compris les protéines dont l'expression augmente spécifiquement suite à un événement précis. Nous avons tout d'abord testé différents acides aminés marqués en combinaison avec des méthodes PIS spécifiques. Ces essais ont permis la détection spécifique des protéines marquées. Cependant, en raison des limitations instrumentales du spectromètre de masse utilisé pour les méthodes PIS, la sensibilité de cette approche s'est révélée être inférieure à une analyse non ciblée réalisée sur un instrument plus récent (Chapitre 2.1). Toutefois, pour l'analyse différentielle de deux milieux de culture conditionnés par des cellules cancéreuses humaines, nous avons utilisé le marquage métabolique pour distinguer les protéines d'origine cellulaire des protéines non marquées du sérum présentes dans les milieux de culture (Chapitre 2.2). Parallèlement, nous avons développé une nouvelle méthode de quantification nommée IBIS, qui utilise des paires d'isotopes stables d'acides aminés capables de produire des ions spécifiques qui peuvent être utilisés pour la quantification relative. La méthode IBIS a été appliquée à l'analyse de deux lignées cellulaires cancéreuses complètement marquées, mais de manière différenciée, par des paires d'acides aminés (Chapitre 2.3). Ensuite, conformément à l'objectif initial de cette thèse, nous avons utilisé une variante pulsée de l'IBIS pour détecter des modifications du protéome dans des cellules HeLa infectée par le virus humain Herpes Simplex-1 (Chapitre 2.4). Ce virus réprime la synthèse des protéines des cellules hôtes afin d'exploiter leur mécanisme de traduction pour la production massive de virions. Comme prévu, de hauts taux de synthèse ont été mesurés pour les protéines virales détectées, attestant de leur haut niveau d'expression. Nous avons de plus identifié un certain nombre de protéines humaines dont le rapport de synthèse et de dégradation (S/D) a été modifié par l'infection virale, ce qui peut donner des indications sur les stratégies utilisées par les virus pour détourner la machinerie cellulaire. En conclusion, nous avons montré dans ce travail que le marquage métabolique peut être employé de façon non conventionnelle pour étudier des dimensions peu explorées en protéomique. Summary : In recent years major technical advancements greatly supported the development of mass spectrometry (MS)-based proteomics. Currently, this technique can efficiently detect, identify and quantify thousands of proteins. However, it is not yet sufficiently powerful to provide a comprehensive analysis of the proteome changes correlated with biological phenomena. The aim of our project was the development of ~a new strategy for the specific detection and quantification of proteomé variations based on measurements of protein synthesis rather than total protein amounts. The rationale for this approach was that changes in protein synthesis more closely reflect dynamic cellular responses than changes in total protein concentrations. Our starting idea was to couple "pulsed" stable-isotope labeling of proteins with a specific MS acquisition method based on precursor ion scan (PIS), to specifically detect proteins that incorporated the label and to simultaneously estimate their abundance, relative to the unlabeled protein isoform. Such approach could highlight proteins with the highest synthesis rate in a given time frame, including proteins specifically up-regulated by a given biological stimulus. As a first step, we tested different isotope-labeled amino acids in combination with dedicated PIS methods and showed that this leads to specific detection of labeled proteins. Sensitivity, however, turned out to be lower than an untargeted analysis run on a more recent instrument, due to MS hardware limitations (Chapter 2.1). We next used metabolic labeling to distinguish the proteins of cellular origin from a high background of unlabeled (serum) proteins, for the differential analysis of two serum-containing culture media conditioned by labeled human cancer cells (Chapter 2.2). As a parallel project we developed a new quantification method (named ISIS), which uses pairs of stable-isotope labeled amino acids able to produce specific reporter ions, which can be used for relative quantification. The ISIS method was applied to the analysis of two fully, yet differentially labeled cancer cell lines, as described in Chapter 2.3. Next, in line with the original purpose of this thesis, we used a "pulsed" variant of ISIS to detect proteome changes in HeLa cells after the infection with human Herpes Simplex Virus-1 (Chapter 2.4). This virus is known to repress the synthesis of host cell proteins to exploit the translation machinery for the massive production of virions. As expected, high synthesis rates were measured for the detected viral proteins, confirming their up-regulation. Moreover, we identified a number of human proteins whose synthesis/degradation ratio (S/D) was affected by the viral infection and which could provide clues on the strategies used by the virus to hijack the cellular machinery. Overall, in this work, we showed that metabolic labeling can be employed in alternative ways to investigate poorly explored dimensions in proteomics.

Prevalence of the metabolic syndrome in the Seychelles according to different definitions, contribution of components, and agreement between different definitions

Background: The metabolic syndrome (MS) represents a cluster of metabolic disorders that predicts diabetes and cardiovascular disease. Several definitions exist and further descriptive and prospective data are needed to compare these definitions and their significance in different populations. Objective: We examined, in a country of the African region, i) the prevalence of MS according to three major definitions (ATP, IDF, WHO); ii) the contribution of individual MS components; and iii) the agreement between the three considered definitions. We also examined the prevalence among diabetics and non-diabetics. Methods: We conducted an examination survey in a sample representative of the general population aged 25-64 of the Seychelles (Indian Ocean, African region), attended by 1255 persons (participation rate of 80.2%). Results: The prevalence of MS was similar with either definition of MS in men (24%--25%) but differed in women (WHO: 25%, ATP: 32%; IDF: 35%). Upon exclusion of diabetic persons, the prevalence was 5-10% lower for all three MS definitions: most diabetic persons had MS although a substantial proportion of diabetic men aged 45--64 did not have MS. The following components were found most often among persons with MS: 90% had high blood pressure (HBP) and 78% had obesity (ATP); 95% had obesity and 84% had HBP (WHO), and 89% had HBP and 75% had impaired glucose regulation (IDF) - not considering impaired glucose regulation and obesity that are compulsory components of the WHO and IDF definitions, respectively. Among persons with MS based on either of the three definitions (37% of total population), less than 80% met both ATP and IDF criteria, 67% both WHO and IDF criteria, 54% both WHO and ATP criteria and only 37% met all three definitions. Conclusion: We found a fairly high prevalence of MS in an African population. However, because there was only poor agreement between the 3 MS definitions, the fairly similar proportions of MS based on ATP, IDF or WHO definitions identified, to a substantial extent, different subjects as having MS.

Glucose competence of the hepatoportal vein sensor requires the presence of an activated glucagon-like peptide-1 receptor.

Activation of the hepatoportal glucose sensors by portal glucose infusion leads to increased glucose clearance and induction of hypoglycemia. Here, we investigated whether glucagon-like peptide-1 (GLP-1) could modulate the activity of these sensors. Mice were therefore infused with saline (S-mice) or glucose (P-mice) through the portal vein at a rate of 25 mg/kg. min. In P-mice, glucose clearance increased to 67.5 +/- 3.7 mg/kg. min as compared with 24.1 +/- 1.5 mg/kg. min in S-mice, and glycemia decreased from 5.0 +/- 0.1 to 3.3 +/- 0.1 mmol/l at the end of the 3-h infusion period. Coinfusion of GLP-1 with glucose into the portal vein at a rate of 5 pmol/kg. min (P-GLP-1 mice) did not increase the glucose clearance rate (57.4 +/- 5.0 ml/kg. min) and hypoglycemia (3.8 +/- 0.1 mmol/l) observed in P-mice. In contrast, coinfusion of glucose and the GLP-1 receptor antagonist exendin-(9-39) into the portal vein at a rate of 0.5 pmol/kg. min (P-Ex mice) reduced glucose clearance to 36.1 +/- 2.6 ml/kg. min and transiently increased glycemia to 9.2 +/- 0.3 mmol/l at 60 min of infusion before it returned to the fasting level (5.6 +/- 0.3 mmol/l) at 3 h. When glucose and exendin-(9-39) were infused through the portal and femoral veins, respectively, glucose clearance increased to 70.0 +/- 4.6 ml/kg. min and glycemia decreased to 3.1 +/- 0.1 mmol/l, indicating that exendin-(9-39) has an effect only when infused into the portal vein. Finally, portal vein infusion of glucose in GLP-1 receptor(-/-) mice failed to increase the glucose clearance rate (26.7 +/- 2.9 ml/kg. min). Glycemia increased to 8.5 +/- 0.5 mmol/l at 60 min and remained elevated until the end of the glucose infusion (8.2 +/- 0.4 mmol/l). Together, our data show that the GLP-1 receptor is part of the hepatoportal glucose sensor and that basal fasting levels of GLP-1 sufficiently activate the receptor to confer maximum glucose competence to the sensor. These data demonstrate an important extrapancreatic effect of GLP-1 in the control of glucose homeostasis.

Reducing the learning curve for the treatment of morphoeic (sclerosing) basal cell carcinoma of the face.

The treatment of morphoeic (or sclerosing) basal cell carcinoma (mBCC) of the face is associated with high rates of incomplete excision and recurrence. A principal risk factor for incomplete resection is the grade of surgeon. We did a prospective, randomised study of 40 consecutive patients with mBCC of the face. The extent of the tumour was assessed under standard conditions by consultant surgeons and compared with assessments by resident surgeons with the help of the Varioscope, a combination of microscope and loupe glasses with strong illumination and a maximal magnification of 7x. The data from a former retrospective study of all excisions of mBCC of the face during a five-year period at the hospital served as control. Residents with the support of the Varioscope achieved a rate of incomplete excisions similar to that of consultants under standard conditions. There was a significant reduction of the rate of incomplete resections by resident surgeons thanks to high magnification and good lighting (p=0.02). High magnification and good lighting were useful in learning how to recognise skin changes associated with mBCC of the face and achieving a low rate of incomplete excisions.