Serum ghrelin in infants with protein-energy malnutrition.

BACKGROUND: Ghrelin is an appetite and weight physiologic controller. The question is whether there is a relation between ghrelin and protein-energy malnutrition (PEM). Our aim was to assess serum ghrelin in these patients and its relation to different patient variables. METHODS: A cross-sectional study was conducted on 30 PEM infants (12 marasmic=Ia, 10 kwashiorkor=Ib and 8 marasmic kwashiorkor=Ic) and 15 age and sex matched controls (II). Plasma ghrelin was measured in all subjects using radioimmunoassay with thorough medical history and clinical assessment. RESULTS: The mean serum ghrelin levels were significantly higher among the 3 patient subgroups than controls with no significant inter-subgroup differences. The presence of intestinal parasitic infestations or edema, type of milk feeding and gender had no significant effects on serum ghrelin levels. CONCLUSION: Serum ghrelin is elevated in PEM as an adapting consequence of the malnutrition rather than a primary event. Although this elevation may not be helpful to correct the growth failure because of deficient nutrients, it may prove to have a role in the catch up phenomenon after the recovery. Further research should be directed toward therapeutic trials of ghrelin in the recovery phase.

Regulation of neuron-specific enolase isozyme levels during differentiation of murine neuroblastoma cell cultures.

A specific event which accompanies the terminal differentiation of most neurons is the isozymic enolase transition from the ?? form to the ?? and ?? adult neuronal forms. It is partly expressed during maturation of a mouse neuroblastoma clonal cell line (NIE-115). We demonstrate, in these cell cultures, that the significant increase in the concentration of ? gene product, expressed as ?? enolase during differentiation, is due to a parallel and similar increase in its synthesis. The capacities of poly (A)(+) RNA from undifferentiated and differentiated cultures to direct the synthesis of ? gene product were compared in a reticulocyte cell-free protein-synthesizing system. This translating capacity is stimulated in the same proportion as the rate of synthesis of ? antigen in differentiating cell cultures. Therefore the increase in the level of ? protein (expressed mostly as ?? enolase) during differentiation results from the increased translating activity or relative amount of ?mRNA.

Developmental changes in translatable mRNAs for the cerebral enolase isozymes alphaalpha and gammagamma.

Using the rabbit reticulocyte cell-free translation system we have estimated during ontogenesis the proportions of in vitro translatable alpha and gamma brain enolase mRNAs, which are two minor mRNA species. No polypeptide precursor to these enzyme subunits appears to be synthesized during translation in vitro. During brain development, the changes in translatable alpha and gamma mRNA content seem to parallel those of the corresponding antigens. The proportion of each of the enolase mRNAs is highest in adult mouse brain. Mechanisms controlling alpha and gamma antigen expression are discussed. In order to prepare the specific cDNA probes, purification of alpha and gamma mRNAs was undertaken.

Developmental studies with the 14-3-2 antigen and the neuron specific enolase (NSE) associated activities-I.

We have compared the rodent developmental pattern of the 14-3-2 antigen estimated by a microcomplement fixation technique with that of the cerebral enolases. Chromatographic separation of enolase isozymes on microcolumns demonstrates that the embryonic neuron specific enolase is firstly and mostly represented by the ?? isozyme. The most important increase in 14-3-2 antigen and ?? enolase occurs between post-natal days 7th and 15th. By post-natal day 30, adult levels have been reached. An interesting observation is-during embryonic development-the decrease in the specific activity of the cerebral enolase isozyme ??. This could be explained by the replacement-in neuroblasts-of ?? enolase by neuron specific enolase. A comparison between 14-3-2 antigen and neuron specific enolase (??) purified by completely different methods is presented. The 14-3-2 antigen exhibits an enolase specific activity comparable to that of purified enzyme and has the same electrophoretic mobility. Antibodies raised against either antigen have an identical specificity. Pre and post-natal developmental pattern in rodent brains are similar for both proteins. Thus neuron specific 14-3-2 antigen is identical to neuron specific enolase. Thus we have precisely described the ontogenic transition between the three cerebral enolase isozymes at the tissue level. This study is completed by the analysis of these transitions at the neuronal cell level, using homogenous cell lines (Part II of this paper).

Transition between isozymic forms of enolase during in vitro differentiation of neuroblastoma cells-II.

An analysis of enolase expression during differentiation of neuroblastoma clones in homogeneous culture is presented. The enolases expressed in these neuroblast-like cells are identical to those of mouse brain with respect to the examined properties. Our biochemical investigation has premitted us to demonstrate formally that neuroblastoma cells undergo a transition from the embryonic ?? form to the neuronal ?? form and contain both enolases as well as the ?? hybrid form during maturation. These results suggest that the same phenomenon must exist in vivo for neuroblasts. In neuroblastoma cells, an increase in both ?? and ?? neuron specific enolases is related to cell maturation and expression of the ?? form precedes that of the ?? form during differentiation. Modulation of neuronal enolase activities is similar in the various conditions of differentiation studied and appears not to be necessarily related with morphological differentiation, although concomitant with an arrest of cell division. The evolution of specific neuronal enolases in neuroblastoma cells parallels that observed in vivo, in brain from embryonic day 15 to post-natal day 7. Moreover, at least one treatment (dimethylsulfoxide) causes an important decrease in the high specific ?? activity of these cells as occurs in vivo. This enolase can therefore also be considered as a biochemical marker for neuroblastoma maturation. As observed with other markers and other cell types, neuroblastoma cells in culture express an immature biochemical differentiation of the enolase isozymes.

Identification of rat brain polysomes synthesizing the brain specific enolase (14.3.2 protein), S100 protein and alpha and beta tubulin subunits.

Polysomes prepared from frozen rat brain powder were fractionated by centrifugation in a sucrose gradient. Individual fractions were used to program a reticulocyte lysate in a run-off reaction. The products of cell-free synthesis were assayed for the brain-specific enolase (14.3.2 protein) and S100 protein by immunoprecipitation with specific antisera and for tubulin by two-dimensional electrophoresis in polyacrylamide slab gels. The relative synthesis of these proteins by unfractionated free brain polysomes were 0.1 per cent, 0.05 per cent and 0.7 per cent respectively. After centrifugation in a sucrose gradient polysomes synthesizing S100 protein were separated from those synthesizing the other two markers. There was a threefold enrichment in the specific messenger RNA activity for each of the three proteins studied in their respective peak fractions of polysomes.

Comparative structural studies of the active site of ATP: guanidine phosphotransferases. The essential cysteine tryptic peptide of taurocyamine kinase from Arenicola marina.

The active cysteinyl residues of dimeric taurocyamine kinase from Arenicola marina were labelled with N-ethyl-[1-14C]maleimide. The resulting inactivated N-ethyl-[1-14C]succinimido enzyme was then subjected to tryptic hydrolysis. The peptide containing the labelled essential cysteinyl residue was isolated. The amino acid sequence of this peptide is Leu-Gly-Tyr-Leu-Gly-Thr-[14C]-Cys-Pro-Thr-Asn-Ile-Gly-Leu-Arg. This sequence is very similar to that of homologous ATP:guanidine phosphotransferases previously studied, arginine kinase from Homarus vulgaris muscle, creatine kinase from ox brain and ox muscle, and from rabbit muscle, and lombricine kinase from Lubricus terrestris.