Lower striatal dopamine D2/3 receptor availability in obese compared with non-obese subjects

Background: Obesity is a result of a relative excess in energy intake over energy expenditure. These processes are controlled by genetic, environmental, psychological and biological factors. One of the factors involved in the regulation of food intake and satiety is dopaminergic signalling. A small number of studies have reported that striatal dopamine D-2/D-3 receptor [D2/3R] availability is lower in morbidly obese subjects. Methods: To confirm the role of D2/3R in obesity, we measured striatal D2/3R availability, using [I-123]IBZM SPECT, in 15 obese women and 15 non-obese controls. Results: Striatal D2/3R availability was 23% (p = 0.028) lower in obese compared with non-obese women. Conclusion: This study is an independent replication of the finding that severely obese subjects have lower striatal D2/3R availability. Our findings invigorate the evidence for lower striatal D2/3R availability in obesity and confirm the role of the striatal dopaminergic reward system in obesit

The dopaminergic system in patients with functional dyspepsia analysed by single photon emission computed tomography (SPECT) and an alpha-methyl-para-tyrosine (AMPT) challenge test

Functional dyspepsia (FD) is a chronic condition characterized by upper abdominal symptoms without an identifiable cause. While the serotonergic system is thought to play a key role in the regulation of gut physiology, the role of the dopaminergic system, which is important in the regulation of visceral pain and stress, is under-studied. Therefore, this study investigated the dopaminergic system and its relationship with drinking capacity and symptoms in FD patients. In FD patients and healthy volunteers (HV) the dopaminergic system was investigated by in-vivo assessment of central dopamine D2 receptors (D2Rs) with [I-123]IBZM SPECT and by an acute, but reversible, dopamine depletion alpha-methyl-para-tyrosine (AMPT) challenge test. A nutrient drink test was performed to investigate the association between maximal ingested volume, evoked symptoms, and D2Rs. The HV subjects comprised 12 women and 8 men (mean age 31 +/- 3 years), and the FD patients comprised 5 women and 3 men (mean age 39 +/- 5 years). The FD patients had a lower left plus right average striatal binding potential (BPNP) for the caudate nucleus (p = 0.02), but not for putamen (p = 0.15), which in the FD patients was correlated with maximal ingested volume (r = 0.756, p = 0.03). The D2R BPNP in the putamen was correlated with nausea (r = 0.857, p = 0.01). The acute dopamine depletion test, however, failed to reveal differences in prolactin release between the FD patients and the HV subjects. These preliminary data suggest that chronic rather than acute alterations in the dopaminergic system may be involved in the pathogenesis of FD. Further studies are required to reproduce our novel findings and to evaluate to what extent the dopaminergic changes may be secondary to abnormalities in serotonergic pathway

Assignment of the gene for cytosolic alanine aminotransferase (AAT1) to human chromosome 8

The segregation of human cytosolic alanine aminotransferase (AAT1) and the individual human chromosomes has been studied in 27 secondary and tertiary rat hepatoma-human (liver) fibroblast hybrids. The staining solution used to visualize AAT activity on starch gels was specific for AAT since it was visualized only when all components of the stain were present. The locus for human AAT1 has been assigned to chromosome 8

Ecological conditions, flora and vegetation of a large doline in the Mecsek Mountains (South Hungary)

Vegetation-environment relationships were investigated in a large doline of the Mecsek Mts (South Hungary). To reveal the vegetation pattern, we collected vegetation data and environmental variables along a 243 m long transect. Atotal of 144 vascular plant species and 4 vegetation types were identified in the doline.We found that both the species composition and the vegetation pattern are significantly influenced by air temperature, air humidity, soil moisture and altitude. Our results confirm the putative temperature and vegetation inversion in the doline

Scope and limitations of rotating-frame nuclear Overhauser enhancement spectroscopy applied to oligosaccharides

Two-dimensional rotating-frame nuclear Overhauser enhancement spectroscopy has been applied to milk oligosaccharides containing the blood-group determinants Lea, Led, or Leb. The results indicate a large number of dipolar interactions that are consistent with the preferred conformations described for these blood-group determinants. Despite careful experimental conditions, coherent transfer processes are not suppressed completely, allowing only a qualitative evaluation of the nuclear Overhauser data. The 1H- and 13C-n.m.r. spectra are assigned by comparison with literature data and by application of two-dimensional 13C-1H shift-correlation spectroscopy

Conformational analysis of the sialylα(2→3/6)N-acetyllactosamine structural element occurring in glycoproteins, by two-dimensional NOE 1H-NMR spectroscopy in combination with energy calculations by hard-sphere exo-anomeric and molecular mechanics force-field with hydrogen-bonding potential

The conformation is described of the sialylalpha(2-> 3/6)N-acetyllactosamine structural element, frequently occurring in glycoproteins. NOE spectroscopy of NeuAcalpah(2-> 3) Galbeta(1-> 4)GlcNAcbeta(1-> N)Asn and NeuAcalpha-(2-> 6)Galbeta(1-> 4)GlcNAcbeta(1-> N)Asn is presented and for each glycosidic linkage, except for the alpha(2->6)-linkage, a number of interglycosidic NOEs are measured. The analysis of these effects is performed using a full relaxation matrix. Analysis of intraresidue NOEs provides a calibration of the calculation method. Hard-sphere exo-anomeric (HSEA) energy calculations indicate a single conformation for the beta(1-> 4)-linkage in both compounds, both being consistent with the NOE data. HSEA and molecular-mechanics force-field with hydrogen-bonding potential energy calculations both indicate the existence of three preferred conformations for the alpha(2-> 3)-linkage. The analysis of the NOE spectra are consistent with a distribution over two or three of these conformations; by combination with the energy diagram for this linkage the existence of onyl a single conformation can be excluded. The NOE spectrum of the compound with the alpha(2-> 6)-linkage indicates a gt orientation for the Gal C-6 hydroxymethyl group. On this basis, the HSEA energy calculations for the alpha(2->6)-linkage indicate an extended low-energy surface with a number of preferred conformations. The absence of NOEs across this linkage is interpreted in terms of a non-rigid, but overall folded conformation of the NeuAcalpha(2->6)Galbeta(1->4)GlcNAcbeta structural element. This provides an explanation for the shift effects induced by alpha(2->6) attachment of NeuAc to the N-acetyllactosamine unit

Structure of α-D-N-acetyl-1-O-methylneuraminic acid methyl ester

CI3H23NO9, Mr=337"33, orthorhombic, P2~212~, a = 8.8479 (9), b = 9.691 (2), c = 18.121 (4) A, V = 1553.8 (5)/~3, Z = 4, Ox = 1.442 Mg m -3, ,~(Mo Ka) = 0-71073 A, /z(Mo Ka) =0.11mm-~, F(000)=720, T=100K, final R= 0.034 for 3398 observed diffractometer data. The conformation of the glycerol side chain is the same as in the structures of the two fl forms of Nacetylneuraminic acid. The crystal consists of a twodimensional network of hydrogen-bonded molecules and in the third direction there are only hydrophobic contacts