Correlation between faecal microbial community structure and cholesterol-to-coprostanol conversion in the human gut

Intensity of the cholesterol-to-coprostanol conversion in the intestine, as assessed by the coprostanol-to-cholesterol ratio in faeces, was found highly variable among 15 human volunteers, ranging from absent to almost complete cholesterol conversion. The number of coprostanoligenic bacteria in the same faecal samples, as estimated by the most probable number method, was found to be less than 10(6) cellsg-1 of fresh stools in the low-to-inefficient converters and at least 10(8) cellsg-1 of fresh stools in the highest converters, indicating that the population level of cultivable faecal coprostanoligenic bacteria correlated with the intensity of cholesterol-to-coprostanol conversion in the human gut. Microbial communities of the samples were profiled by temporal temperature gradient gel electrophoresis (TTGE) of bacterial 16S rRNA gene amplicons. Dendrogram analysis of the TTGE profiles using the Pearson product moment correlation coefficient and a unweighted pair group method with arithmetic averages (UPGMA) algorithm clearly separated banding patterns from low-to-inefficient and high converters in two different clusters suggesting a relationship between TTGE profiles and coprostanoligenic activity. Principal components analysis further demonstrated that a large subset of bands rather than some individual bands contributed to this clustering.     

Genetic analysis carried out on blood-spots of phenylalanine hydroxylase-deficient newborns detected by northeastern Italian neonatal screening

The aim of this work was to perform genetic analysis on 18 different blood-spot samples collected from neonates detected as hyperphenylalaninemic by Northeastern Italian screening program. DNA was extracted from blood-spots. Exons/introns of PAH gene were amplified by polymerase chain reaction (PCR), and PCR products were purified and sequenced with both forward and reverse primers. The most frequent mutations were IVS12nt1g>a (16.7%) and R408W, P281L and L48S (all together 11.1%). As expected, compound heterozygosity was the usual finding; homozygosity was found only in two patients with R158Q and IVS2nt5g>c mutations. The V230I mutation was reported for the first time in Italy. We found six previously described polymorphisms (V245V, IVS4nt47c>t, IVS2nt19t>c, IVS3nt-22c>t, IVS5nt-54a>g, and E280>Q280). To our knowledge, four genotypes were not previously described: R158Q/V230I present in one patient with classical PKU; and L48S/R408Q, A403V/IVS2nt-13t>g, and G272X/V230I present in patients showing HPA phenotype. Most of the mutations were located in the exons 12 and 7 and in exon/intron 2 (83.3% detection of total mutations in PKU or HPA patients of Northeastern Italy). From a practical viewpoint, the genetic analysis of blood-spots collected on Guthrie cards for neonatal screening for PKU could be a simple method to establish the genotype of neonates. Consequently, the genotype/phenotype correlation could lead to a more accurate diagnosis and prognosis for families.     

Portal sensing of intestinal gluconeogenesis is a mechanistic link in the diminution of food intake induced by diet protein

Protein feeding is known to decrease hunger and subsequent food intake in animals and humans. It has also been suggested that glucose appearance into portal vein, as occurring during meal assimilation, may induce comparable effects. Here, we connect these previous observations by reporting that intestinal gluconeogenesis (i.e., de novo synthesis of glucose) is induced during the postabsorptive time (following food digestion) in rats specifically fed on protein-enriched diet. This results in glucose release into portal blood, counterbalancing the lowering of glycemia resulting from intestinal glucose utilization. Comparable infusions into the portal vein of control postabsorptive rats (fed on starch-enriched diet) decrease food consumption and activate the hypothalamic nuclei regulating food intake. Similar hypothalamic activation occurs on protein feeding. All these effects are absent after denervation of the portal vein. Thus, portal sensing of intestinal gluconeogenesis may be a novel mechanism connecting the macronutrient composition of diet to food intake.     

Exogenously added fibroblast growth factor 2 (FGF-2) to NIH3T3 cells interacts with nuclear ribosomal S6 kinase 2 (RSK2) in a cell cycle-dependent manner

Fibroblast growth factor 2 (FGF-2) has been detected in the nuclei of many tissues and cell lines. Here we demonstrate that FGF-2 added exogenously to NIH3T3 cells enters the nucleus and interacts with the nuclear active 90-kDa ribosomal S6 kinase 2 (RSK2) in a cell cycle-dependent manner. By using purified proteins, FGF-2 is shown to directly interact through two separate domains with two RSK2 domains on both sides of the hydrophobic motif, namely the NH2-terminal kinase domain (residues 360-381) by amino acid Ser-117 and the COOH-terminal kinase domain (residues 388-400) by amino acids Leu-127 and Lys-128. Moreover, this interaction leads to maintenance of the sustained activation of RSK2 in G1 phase of the cell cycle. FGF-2 mutants (FGF-2 S117A, FGF-2 L127A, and FGF-2 K128A) that fail to interact in vitro with RSK2 fail to maintain a sustained RSK2 activity in vivo.     

Lysosomal leukocyte beta-D-glucuronidase during enzyme replacement therapy in Fabry disease

OBJECTIVE: Fabry disease results from a deficiency in the activity of alpha-d-galactosidase A and subsequent accumulation of neutral glycosphingolipids in lysosomes. This study investigated whether lysosomal enzymes can indicate biochemical changes in the lysosomal apparatus induced by enzyme replacement therapy (ERT). DESIGN AND METHODS: Eight patients were monitored by clinical and biochemical tests and several lysosomal glycohydrolases were measured in plasma and leucocytes. RESULTS: Before starting ERT, beta-d-glucuronidase in leukocytes was markedly increased. After 1 month of therapy, enzyme levels dropped in all patients. In the patients who regularly followed the therapy, the enzyme levels remained stable for the next 20 months. In one patient who interrupted therapy for 2 months, the enzyme levels rose again. CONCLUSIONS: Lysosomal enzymes can be useful for monitoring biochemical changes in patients with Fabry disease receiving ERT. Though these findings refer to only a small number of patients, the correlation between beta-d-glucuronidase levels and ERT is interesting and might serve as a basis for further studies to define the potential of this enzyme in monitoring the effects of ERT in lysosomal storage disorders.