Clinical Characteristics of Primary Epstein Barr Virus Hepatitis with Elevation of Alkaline Phosphatase and gamma-Glutamyltransferase in Children

PURPOSE: The aim of the present study was to evaluate the clinical characteristics of the primary Epstein-Barr virus (EBV) hepatitis with elevation of both serum alkaline phosphatase (ALP) and gamma-glutamyltransferase (gamma-GT) levels in children. MATERIALS AND METHODS: A retrospective study was performed by reviewing of the medical records of 36 patients who were diagnosed with primary EBV hepatitis. The patients were divided into 2 groups: patients with elevated serum ALP and gamma-GT levels (group 1) and patients without (group 2). RESULTS: The classic features of infectious mononucleosis (fever, pharyngitis and/or tonsillitis, and cervical lymphadenitis) were seen in 20 (57.1%) of group 1 patients and 18 (50.0%) of group 2 patients. Hepatitis with elevated serum ALP and gamma-GT levels were present in 14 (38.9%) of the all patients. Of these patients, Jaundice occurred in only 2 (5.6%). The mean levels of aspartate aminotransferase and alanine aminotransferase (ALT) as well as the number of patients with ALT greater than 400 IU/L were significantly different between the groups (177 IU/L vs. 94 IU/L, 418 IU/L vs. 115 IU/L, and 50.0% vs. 13.6%; p=0.001, p=0.001, p=0.026, respectively). The mean duration of elevated serum ALT levels was 17.5 days in group 1 and 9.0 days in group 2 (p=0.013). All patients recovered fully without any chronic or serious complications. CONCLUSION: Primary EBV hepatitis with predominant biochemical abnormalities of the elevation of ALP and gamma-GT is frequent and mostly anicteric. This may represent a benign disease, but a delay in recovery of liver function as well.

Contribution of Ser463 residue to the enzymatic and autoprocessing activities of Escherichia coli -glutamyltranspeptidase.

A serine residue Ser463, required for proper function of E. coli -glutamyltranspeptidase (EcGGT) was identified by site-directed mutagenesis on the basis of sequence alignment of human, pig, rat, and three bacterial enzymes. Thr-, Asp-, and Lys-substituted variants were overexpressed in E. coli M15 cells and the recombinant proteins were purified to near homogeneity by nickel-chelate chromatography. With the exception of S463T, the other two variants completely lost GGT activity, implying the importance of this residue in EcGGT. Moreover, substitution of Ser463 with either Lys or Asp impaired the capability of autocatalytic processing of the precursor into - and -subunit. Computer modeling showed that the critical bonding distance of Gln390 C-Thr391 OG1 was significantly increased in S463D and S463K, indicating that these distance changes might be responsible for the lack of enzyme maturation. Measurements of intrinsic tryptophan fluorescence revealed alteration of the microenvironment of aromatic amino acid residues in S463D and S463K, while circular dichroism (CD) spectra were nearly identical for wild-type and all mutant enzymes. The temperature-dependent signal in the far-UV region for S463T was consistent with that of wild-type enzyme, but S463D and S463K showed a different sensitivity towards temperature-induced denaturation. These results implied that a significant conformational change occurred as a result of Asp- and Lys-substitution.

Site-directed mutagenesis of conserved Thr407, Asp433 and Met464 residues in small subunit of Escherichia coli gamma-glutamyltranspeptidase.

Sequence comparison showed that residues Thr407, Asp433, and Met464 in the small subunit of Escherichia coli gamma-glutamyltranspeptidase (EcGGT) were conserved in the aligned enzymes. In this study, we further investigated the functional significance of these conserved residues by site-directed mutagenesis. The wild-type and mutant enzymes were overexpressed in the recombinant E. coli M15 cells and purified to near homogeneity by Ni2+-NTA resin. Except M464L, other mutants had shown no GGT activity under enzyme assay conditions and activity staining. Furthermore, mutations on these residues impaired the capability of autocatalytic processing of the enzyme. Based on these observations, it is concluded that these residues play an important role in the enzyme maturation.