Transient stimulation of glucose metabolism by insulin in the 1-day chick embryo.

Effects of insulin upon glucose metabolism were investigated in chick embryos explanted in vitro during the first 30 h of incubation. Insulin stimulated the glucose consumption of the chick gastrula (18 h) and neurula (24 h), but had no effect on the late blastula (0 h:laying) and on the stage of six to eight somites (30 h). The increase in glucose consumption concerned both the embryonic area pellucida (AP) and extraembryonic area opaca (AO). AP responded to a greater extent (50%) and at a lower range of concentrations (0.1-1.0 ng/ml) than AO (30%; 1-100 ng/ml). Insulin had no effect on the oxygen consumption of blastoderms, whereas it stimulated the aerobic lactate production (approximately 70% of the additional glucose consumption was converted to lactate). The nanomolar range of stimulating concentrations suggests that insulin has a specific effect in the chick embryo, and that it could modulate glucose metabolism in ovo as well. The transient sensitivity of the embryo to insulin is discussed in relation to behavior of mesodermal cells.

Secondary amyloidosis: a severe complication of ankylosing spondylitis. Two case-reports.

STUDY OBJECTIVE: To report two cases of amyloidosis secondary to ankylosing spondylitis. PATIENTS AND RESULTS: Of the 47 ankylosing spondylitis patients who have received follow-up at our department over the last few years, two have developed AA amyloidosis. Both have extremely severe, long-standing joint disease, with virtually complete spinal ankylosis and destructive peripheral arthritis of the hips and wrists; one also has tarsal joint destruction. Renal dysfunction was the first manifestation of amyloidosis in both cases. One patient required chronic hemodialysis and developed peritonitis due to colonic perforation, probably at a site of amyloid deposition. CONCLUSIONS: Secondary amyloidosis is a rare complication of ankylosing spondylitis that can cause severe renal and gastrointestinal complications. No treatment capable of clearing established amyloid deposits is available to date.

Effect of carbohydrate overfeeding on whole body macronutrient metabolism and expression of lipogenic enzymes in adipose tissue of lean and overweight humans

OBJECTIVE: Lipids stored in adipose tissue can originate from dietary lipids or from de novo lipogenesis (DNL) from carbohydrates. Whether DNL is abnormal in adipose tissue of overweight individuals remains unknown. The present study was undertaken to assess the effect of carbohydrate overfeeding on glucose-induced whole body DNL and adipose tissue lipogenic gene expression in lean and overweight humans. DESIGN: Prospective, cross-over study. SUBJECTS AND METHODS: A total of 11 lean (five male, six female, mean BMI 21.0+/-0.5 kg/m(2)) and eight overweight (four males, four females, mean BMI 30.1+/-0.6 kg/m(2)) volunteers were studied on two occasions. On one occasion, they received an isoenergetic diet containing 50% carbohydrate for 4 days prior to testing; on the other, they received a hyperenergetic diet (175% energy requirements) containing 71% carbohydrates. After each period of 4 days of controlled diet, they were studied over 6 h after having received 3.25 g glucose/kg fat free mass. Whole body glucose oxidation and net DNL were monitored by means of indirect calorimetry. An adipose tissue biopsy was obtained at the end of this 6-h period and the levels of SREBP-1c, acetyl CoA carboxylase, and fatty acid synthase mRNA were measured by real-time PCR. RESULTS: After isocaloric feeding, whole body net DNL amounted to 35+/-9 mg/kg fat free mass/5 h in lean subjects and to 49+/-3 mg/kg fat free mass/5 h in overweight subjects over the 5 h following glucose ingestion. These figures increased (P<0.001) to 156+/-21 mg/kg fat free mass/5 h in lean and 64+/-11 mg/kg fat free mass/5 h (P<0.05 vs lean) in overweight subjects after carbohydrate overfeeding. Whole body DNL after overfeeding was lower (P<0.001) and glycogen synthesis was higher (P<0.001) in overweight than in normal subjects. Adipose tissue SREBP-1c mRNA increased by 25% in overweight and by 43% in lean subjects (P<0.05) after carbohydrate overfeeding, whereas fatty acid synthase mRNA increased by 66 and 84% (P<0.05). CONCLUSION: Whole body net DNL is not increased during carbohydrate overfeeding in overweight individuals. Stimulation of adipose lipogenic enzymes is also not higher in overweight subjects. Carbohydrate overfeeding does not stimulate whole body net DNL nor expression of lipogenic enzymes in adipose tissue to a larger extent in overweight than lean subjects.

Once-yearly zoledronic acid for treatment of postmenopausal osteoporosis.

BACKGROUND: A single infusion of intravenous zoledronic acid decreases bone turnover and improves bone density at 12 months in postmenopausal women with osteoporosis. We assessed the effects of annual infusions of zoledronic acid on fracture risk during a 3-year period. METHODS: In this double-blind, placebo-controlled trial, 3889 patients (mean age, 73 years) were randomly assigned to receive a single 15-minute infusion of zoledronic acid (5 mg) and 3876 were assigned to receive placebo at baseline, at 12 months, and at 24 months; the patients were followed until 36 months. Primary end points were new vertebral fracture (in patients not taking concomitant osteoporosis medications) and hip fracture (in all patients). Secondary end points included bone mineral density, bone turnover markers, and safety outcomes. RESULTS: Treatment with zoledronic acid reduced the risk of morphometric vertebral fracture by 70% during a 3-year period, as compared with placebo (3.3% in the zoledronic-acid group vs. 10.9% in the placebo group; relative risk, 0.30; 95% confidence interval [CI], 0.24 to 0.38) and reduced the risk of hip fracture by 41% (1.4% in the zoledronic-acid group vs. 2.5% in the placebo group; hazard ratio, 0.59; 95% CI, 0.42 to 0.83). Nonvertebral fractures, clinical fractures, and clinical vertebral fractures were reduced by 25%, 33%, and 77%, respectively (P<0.001 for all comparisons). Zoledronic acid was also associated with a significant improvement in bone mineral density and bone metabolism markers. Adverse events, including change in renal function, were similar in the two study groups. However, serious atrial fibrillation occurred more frequently in the zoledronic acid group (in 50 vs. 20 patients, P<0.001). CONCLUSIONS: A once-yearly infusion of zoledronic acid during a 3-year period significantly reduced the risk of vertebral, hip, and other fractures. (ClinicalTrials.gov number, NCT00049829.)

Secondary contact zones and hybridizations: the case of the lesser white-toothed shrew (Crocidura suaveolens group, Soricidae)

In the present study, we analyzed 58 samples of the lesser white-toothed shrew group (Crocidura suaveolens) from eastern Europe and Turkey, where, according to previous publications, three different mitochondrial and nuclear lineages are present. We sequenced 799 bp of the nuclear BRCA1 gene and 400 bp of the mitochondrial cytochrome b gene to: (1) determine a potential contact zone between the lineages; (2) detect hybridizations and introgressions between them; and (3) comment on the level of reproductive isolation of the different lineages. We revealed two zones of hybridization in Turkey, of which the first occurred west of the Bosphorus Straits (three hybrids) and the second in Anatolia (twelve hybrids). In the latter, the nuclear markers revealed a large zone of hybridization, of approximately 600 km. It also revealed that hybrids of first, second, and later generations are present within the populations, and therefore that the reproductive isolation between the different lineages is weak.

Secondary choriocapillaritis in infectious chorioretinitis.

PURPOSE: To analyse the indocyanine green angiography (ICGA) patterns of hypofluorescence that are compatible with choriocapillaritis that occur secondarily to toxoplasmic retinochoroiditis (ToRC), ocular tuberculosis (including tuberculous choroiditis, TuCR and multifocal serpiginoid choroiditis, TMSC) and syphilitic chorioretinitis (SyCR). METHODS: This was a single centre, retrospective case review study. Patients with a diagnosis of ToRC, TuCR, TMSC or SyCR were identified, their charts were reviewed and fundus photographs, fluorescein angiography (FA) and ICGA pictures were assessed. RESULTS: Indocyanine green angiography was performed at the initial presentation in 63 of the 105 patients with ToRC, in 37 of the 38 patients with TuCR, in six of six patients with TMSC and in two of four patients with SyCR. The following four ICGA patterns indicated choriocapillaritis: extension of hypofluorescence beyond the hypofluorescence of the actual infectious focus as seen on fundus photography or FA (seen only in ToRC and TuCR); small dark dots around the infectious focus (seen only in ToRC); multiple 'confetti-like' hypofluorescent areas or hypofluorescent geographical confluent areas (seen only in TMSC); and widespread areas of nonperfusion visible only in ICGA (seen only in SyCR). CONCLUSIONS: Patients with secondary choriocapillaritis have distinct typical ICGA findings. ICGA is thus an important diagnostic tool that can provide an explanation for otherwise obscure visual loss and that might have diagnostic value for specific conditions like ToRC and SyCR.

A multi-purpose grammar generating a multi-scale integrated analysis of Laos

In this study we propose an application of the MuSIASEM approach which is used to provide an integrated analysis of Laos across different scales. With the term “integrated analysis across scales” we mean the generation of a series of packages of quantitative indicators, characterizing the performance of the socioeconomic activities performed in Laos when considering: (i) different hierarchical levels of organization (farming systems described at the level of household, rural villages, regions of Laos, the whole country level); and (ii) different dimensions of analysis (economic dimension, social dimension, ecological dimension, technical dimension). What is relevant in this application is that the information carried out by these different packages of indicators is integrated in a system of accounting which establishes interlinkages across these indicators. This is a essential feature to study sustainability trade-offs and to build more robust scenarios of possible changes. The multi-scale integrated representation presented in this study is based on secondary data (gathered in a three year EU project – SEAtrans and integrated by other available statistical sources) and it is integrated in GIS, when dealing with the spatial representation of Laos. However, even if we use data referring to Laos, the goal of this study is not that of providing useful information about a practical policy issue of Laos, but rather, to illustrate the possibility of using a multipurpose grammar to produce an integrated set of sustainability indicators at three different levels: (i) local; (ii) meso; (iii) macro level. The technical issue addressed is the simultaneous adoption of two multi-level matrices – one referring to a characterization of human activity over a set of different categories, and another referring to a characterization of land uses over the same set of categories. In this way, it becomes possible to explain the characteristics of Laos (an integrated set of indicators defining the performance of the whole country) in relation to the characteristics of the rural Laos and urban Laos. The characteristics of rural Laos, can be explained using the characteristics of three regions defined within Laos (Northern Laos, Central Laos and Southern Laos), which in turn can be defined (using an analogous package of indicators), starting from the characteristics of three main typologies of farming systems found in the regions.

Predators promote defence of rhizosphere bacterial populations by selective feeding on non-toxic cheaters.

Soil pseudomonads increase their competitiveness by producing toxic secondary metabolites, which inhibit competitors and repel predators. Toxin production is regulated by cell-cell signalling and efficiently protects the bacterial population. However, cell communication is unstable, and natural populations often contain signal blind mutants displaying an altered phenotype defective in exoproduct synthesis. Such mutants are weak competitors, and we hypothesized that their fitness depends on natural communities on the exoproducts of wild-type bacteria, especially defence toxins. We established mixed populations of wild-type and signal blind, non-toxic gacS-deficient mutants of Pseudomonas fluorescens CHA0 in batch and rhizosphere systems. Bacteria were grazed by representatives of the most important bacterial predators in soil, nematodes (Caenorhabditis elegans) and protozoa (Acanthamoeba castellanii). The gacS mutants showed a negative frequency-dependent fitness and could reach up to one-third of the population, suggesting that they rely on the exoproducts of the wild-type bacteria. Both predators preferentially consumed the mutant strain, but populations with a low mutant load were resistant to predation, allowing the mutant to remain competitive at low relative density. The results suggest that signal blind Pseudomonas increase their fitness by exploiting the toxins produced by wild-type bacteria, and that predation promotes the production of bacterial defence compounds by selectively eliminating non-toxic mutants. Therefore, predators not only regulate population dynamics of soil bacteria but also structure the genetic and phenotypic constitution of bacterial communities.

A first attempt of geographically-distributed Multi-scale integrated analysis of societal and ecosystem metabolism (MuSIASEM): mapping human time and energy throughput in metropolitan Barcelona

This study presents a first attempt to extend the “Multi-scale integrated analysis of societal and ecosystem metabolism (MuSIASEM)” approach to a spatial dimension using GIS techniques in the Metropolitan area of Barcelona. We use a combination of census and commercial databases along with a detailed land cover map to create a layer of Common Geographic Units that we populate with the local values of human time spent in different activities according to MuSIASEM hierarchical typology. In this way, we mapped the hours of available human time, in regards to the working hours spent in different locations, putting in evidence the gradients in spatial density between the residential location of workers (generating the work supply) and the places where the working hours are actually taking place. We found a strong three-modal pattern of clumps of areas with different combinations of values of time spent on household activities and on paid work. We also measured and mapped spatial segregation between these two activities and put forward the conjecture that this segregation increases with higher energy throughput, as the size of the functional units must be able to cope with the flow of exosomatic energy. Finally, we discuss the effectiveness of the approach by comparing our geographic representation of exosomatic throughput to the one issued from conventional methods.

Separation of free amino acids in human plasma by capillary electrophoresis with laser induced fluorescence: potential for emergency diagnosis of inborn errors of metabolism.

Free amino acids (AAs) in human plasma are derivatized with 3-(4-carboxybenzoyl)quinoline-2-carboxaldehyde (CBQCA) and analyzed by capillary electrophoresis (CE) with laser induced fluorescence (LIF) detection. The labeling procedure is significantly improved over results reported previously. Derivatization can be completed in 40 min, with concentrations as low as 4 x 10(-8) M successfully labeled in favourable cases. Twenty-nine AAs (including 2 internal standards) are identified and can be reproducibly separated in 70 min. Migration time RSD values for 23 of these AAs were calculated and found in the range from 0.5 to 4%. The rapid derivatization procedure and the resolution obtained in the separation are sufficient for a semi-quantitative, emergency diagnosis of several inborn errors of metabolism (IEM). Amino acid profiles for both normal donor plasma samples and plasma samples of patients suffering from phenylketonuria, tyrosinemia, maple syrup urinary disease, hyperornithinemia, and citrullinemia are studied.

Imaging liver and brain glycogen metabolism at the nanometer scale.

In mammals, glycogen synthesis and degradation are dynamic processes regulating blood and cerebral glucose-levels within a well-defined physiological range. Despite the essential role of glycogen in hepatic and cerebral metabolism, its spatiotemporal distribution at the molecular and cellular level is unclear. By correlating electron microscopy and ultra-high resolution ion microprobe (NanoSIMS) imaging of tissue from fasted mice injected with (13)C-labeled glucose, we demonstrate that liver glycogenesis initiates in the hepatocyte perinuclear region before spreading toward the cell membrane. In the mouse brain, we observe that (13)C is inhomogeneously incorporated into astrocytic glycogen at a rate ~25 times slower than in the liver, in agreement with prior bulk studies. This experiment, using temporally resolved, nanometer-scale imaging of glycogen synthesis and degradation, provides greater insight into glucose metabolism in mammalian organs and shows how this technique can be used to explore biochemical pathways in healthy and diseased states. FROM THE CLINICAL EDITOR: By correlating electron microscopy and ultra-high resolution ion microprobe imaging of tissue from fasting mice injected with (13)C-labeled glucose, the authors demonstrate a method to image glycogen metabolism at the nanometer scale.

Ammonium accumulation and cell death in a rat 3D brain cell model of glutaric aciduria type I.

Glutaric aciduria type I (glutaryl-CoA dehydrogenase deficiency) is an inborn error of metabolism that usually manifests in infancy by an acute encephalopathic crisis and often results in permanent motor handicap. Biochemical hallmarks of this disease are elevated levels of glutarate and 3-hydroxyglutarate in blood and urine. The neuropathology of this disease is still poorly understood, as low lysine diet and carnitine supplementation do not always prevent brain damage, even in early-treated patients. We used a 3D in vitro model of rat organotypic brain cell cultures in aggregates to mimic glutaric aciduria type I by repeated administration of 1 mM glutarate or 3-hydroxyglutarate at two time points representing different developmental stages. Both metabolites were deleterious for the developing brain cells, with 3-hydroxyglutarate being the most toxic metabolite in our model. Astrocytes were the cells most strongly affected by metabolite exposure. In culture medium, we observed an up to 11-fold increase of ammonium in the culture medium with a concomitant decrease of glutamine. We further observed an increase in lactate and a concomitant decrease in glucose. Exposure to 3-hydroxyglutarate led to a significantly increased cell death rate. Thus, we propose a three step model for brain damage in glutaric aciduria type I: (i) 3-OHGA causes the death of astrocytes, (ii) deficiency of the astrocytic enzyme glutamine synthetase leads to intracerebral ammonium accumulation, and (iii) high ammonium triggers secondary death of other brain cells. These unexpected findings need to be further investigated and verified in vivo. They suggest that intracerebral ammonium accumulation might be an important target for the development of more effective treatment strategies to prevent brain damage in patients with glutaric aciduria type I.

Effects of infused fructose on endogenous glucose production, gluconeogenesis, and glycogen metabolism.

To determine the mechanisms that prevent an increase in gluconeogenesis from increasing hepatic glucose output, six healthy women were infused with [1-13C]fructose (22 mumol.kg-1.min-1), somatostatin, insulin, and glucagon. In control experiment, non-13C-enriched fructose was infused at the same rate without somatostatin, and [U-13C]glucose was infused to measure specifically plasma glucose oxidation. Endogenous glucose production (EGP, [6,6-2H]glucose), net carbohydrate oxidation (CHOox, indirect calorimetry), and fructose oxidation (13CO2) were measured. EGP rate did not increase after fructose infusion with (13.1 +/- 1.2 vs. 12.9 +/- 0.3 mumol.kg-1.min-1) and without (10.3 +/- 0.5 vs. 9.7 +/- 0.5 mumol.kg-1.min-1) somatostatin, despite the fact that gluconeogenesis increased. Nonoxidative fructose disposal, corresponding mainly to glycogen synthesis, was threefold net glycogen deposition, the latter calculated as fructose infusion minus CHOox (14.8 +/- 1.1 and 4.3 +/- 2.0 mumol.kg-1.min-1). It is concluded that 1) the mechanism by which EGP remains constant when gluconeogenesis from fructose increases is independent of changes in insulin and 2) simultaneous breakdown and synthesis of glycogen occurred during fructose infusion.