Human NADPH-P450 oxidoreductase modulates the level of cytochrome P450 CYP2D6 holoprotein via haem oxygenase-dependent and -independent pathways

NADPH-P450 oxidoreductase (CPR) is essential for the activity of cytochrome P450 (P450). Previous studies demonstrated that CPR regulates the levels of various P450 isoforms in vitro. We investigated the mechanistic basis for this regulation. By transfection of Chinese hamster ovary DUKXB11 cells we obtained the cell line DUKX/2D6, which expressed human CYP2D6, a P450 isoform. Subsequently, DUKX/2D6 cells were transfected with human CPR cDNA to generate the cell line DUKX/2D6/CPR-3. Expression of recombinant CPR decreased the level of spectrally detectable CYP2D6 holoprotein in DUKX/2D6/CPR-3 cells by 70%, whereas the level of immunodetectable apoprotein remained unchanged. Addition of the radical scavenger DMSO increased levels of CYP2D6 holoenzyme in DUKX/2D6/CPR-3 cells but not in DUKX/2D6 cells. A similar effect was noted when cells were grown in the presence of hemin. Importantly, combined treatment with DMSO and hemin increased levels of CYP2D6 holoenzyme in DUKX/2D6/CPR-3 but not in DUKX/2D6 cells even further than either treatment alone. None of these treatments affected the level of immunodetectable CYP2D6. This demonstrates that expression of CPR increases production of damaging radicals but also that CPR may alter haem homoeostasis. In agreement with this, the activity of haem oxygenase, a rate-limiting enzyme in haem metabolism, was compared with that in DUKX/DHFR control cells (expressing dihydrofolate reductase), and was 3-fold higher in DUKX/2D6/CPR-3 but similar in DUKX/2D6 cells. Furthermore, treatment of cells with sodium arsenite increased levels of haem oxygenase concomitant with a marked decrease of spectrally detectable CYP2D6 and a rise in levels of ferritin, which sequesters free iron released from the destruction of haem. These data demonstrate that CPR regulates P450 activity by supplying electrons and also by altering P450 levels via radical-and haem oxygenase-mediated pathways.

Detection of leukemic cells in the CD34(+)CD38(-) bone marrow progenitor population in children with acute lymphoblastic leukemia

Successful autologous hematopoietic stem cell (HSC) transplantation in childhood acute lymphoblastic leukemia (ALL) requires the ability to either selectively kill the leukemia cells or separate normal from leukemic HSC. Based on previous studies showing that more than 95% of childhood B-lineage ALL express CD38, this study evaluated whether normal CD34(+)CD38(-) progenitors from children with B-lineage ALL could be isolated by flow cytometry. CD34(+) cells from bone marrow samples from 10 children with B-lineage ALL were isolated at day 28 of treatment, when clinical remission had been attained. The CD34(+) progenitor cells were flow cytometrically sorted into CD34(+)CD38(+) and CD34(+)CD38(-) populations. The absolute numbers of CD34(+)CD38(-) cells that could be isolated ranged from 401 to 6245. The cells were then analyzed for the presence of clonotypic rearrangements of the T-cell receptor (TCR) Vdelta2-Ddelta3 locus. Only patients whose diagnostic marrow had an informative TCR Vdelta2-Ddelta3 rearrangement were included in this study. Detection thresholds were typically 10(-4) to 10(-5) leukemic cells in normal marrow. In 6 of 10 samples analyzed, the sorted CD34(+)CD38(-) cells had no detectable Vdelta2-Ddelta3 rearrangements. In 4 cases, the clonotypic leukemic Vdelta2-Ddelta3 rearrangement was detected in the CD34(+)CD38(-) population, indicating that the putative normal HSC population also contained leukemic cells. The data indicate that although most childhood ALL cells express CD34 and CD38, leukemic cells are also frequently present in the CD34(+)CD38(-) population. Therefore, strategies to isolate and transplant normal HSC from children with ALL will require a more stringent definition of the normal HSC than the CD34(+)CD38(-) phenotype. (Blood. 2001;97:3925-3930)

Synthesis and reactivity of the catechol metabolites from the equine estrogen, 8,9-dehydroestrone

The risk factors for women developing breast and endometrial cancers are all associated with a lifetime of estrogen exposure. Estrogen replacement therapy in particular has been correlated with an increased cancer risk. Previously, we showed that the equine estrogens equilin and equilenin, which are major components of the widely prescribed estrogen replacement formulation Premarin, are metabolized to highly cytotoxic quinoids which caused oxidative stress and alkylation of DNA in vitro [Bolton, J. L., Pisha, E., Zhang, F., and Qiu, S. Chem. Res. Toxicol. 1998, 11, 1113-1127]. In this study, we have synthesized 8,9-dehydroestrone (a third equine estrogen component of Premarin) and its potential catechol metabolites, 4-hydroxy-8,9-dehydroestrone and 2-hydroxy-8,9-dehydroestrone. Both 2-hydroxy-8,9-dehydroestrone and 4-hydroxy-8,9-dehydroestrone were oxidized by tyrosinase or rat liver microsomes to o-quinones which reacted with GSH to give one mono-GSH conjugate and two di-GSH conjugates. Like endogenous estrogens, 8,9-dehydroestrone was primarily converted by rat liver microsomes to the 2-hydroxylated rather than the 4-hydroxylated o-quinone GSH conjugates; the ratio of 2-hydroxy-8,9-dehydroestrone versus 4-hydroxy-8,9-dehydroestrone was 6:1. Also in contrast to experiments with equilin, 4-hydroxyequilenin was not observed in microsomal incubations with 8,9-dehydroestrone or its catechols. The behavior of 2-hydroxy-8,9-dehydroestrone was found to be more complex than 4-hydroxy-8,9-dehydroestrone as GSH conjugates resulting from 2-hydroxy-8,9-dehydroestrone were detected even without oxidative enzyme catalysis. Under physiological conditions, 2-hydroxy-8,9-dehydroestrone isomerized to 2-hydroxyequilenin to form the very stable 2-hydroxyequilenin catechol; however, 4-hydroxy-8,9-dehydroestrone was found to be stable under similar conditions. Finally, preliminary studies conducted with the human breast tumor S-30 cell lines demonstrated that the catechol metabolites of 8,9-dehydroestrone were much less toxic than 4-hydroxyequilenin (20-40-fold). These results suggest that the catechol metabolites of 8,9-dehydroestrone may have the ability to cause cytotoxicity in vivo primarily through formation of o-quinones; however, most of the adverse effects of Premarin estrogens are likely due to formation of 4-hydroxyequilenin o-quinone from equilin and equilenin.

An epidemiological survey on neonatal jaundice in China

OBJECTIVE

To provide epidemiological data for revising the diagnostic criteria of neonatal hyperbilirubinemia in China.

METHODS

A survey was performed among full-term infants in multiple centers throughout the country. From less than 24 hours after birth, the infants' bilirubin levels were measured every day until the peak level fell to less than 68.4 mumol/L. Auditory brainstem responses were assessed in 56 infants randomly chosen from those with serum bilirubin levels of higher than 220.5 mumol/L.

RESULTS

Jaundice in most infants was detected at 2-3 days after birth. The bilirubin level usually reached a peak level of 204 +/- 54.69 mumol/L at 5 days after birth and then fell. Among the 875 infants, the serum bilirubin levels in 34.4% of neonates were higher than 220.5 mumol/L. The mean serum bilirubin level of the infants during the first week after birth varied with geography (P < 0.001) and season (P < 0.001). The serum bilirubin level was significantly associated with gestation age (P < 0.01), delivery method (P < 0.01), weight loss (P < 0.001), and PCV elevation (P < 0.001) during the first three days after birth.

CONCLUSIONS

The start time of neonatal jaundice was similar to that reported elsewhere, but the mean peak level in our study was higher than the reported. It is suggested that the diagnostic criteria for neonatal hyperbilirubinemia in China should be strict.

[An off site petroleum-contaminated soil bioremediation technology: soil compositing in windrow]

With off-site bioremediation technology, a soil contaminated by crude oil from Liaohe Oil Field was treated on a 20 x 10 m prepared bed. 8 composting windrow units were set, each measured 8 m in length, 2 m in width, and 0.35 m in height. The results showed that when the pollutant petroleum hydrocarbon(TPH) was within the range of 4.16-7.72 g.100 g-1 soil, the total degradation rate of TPH reached 45.19%-56.74% after 53 days operation, which indicated that a technological basis would be provided for the bioremediation of oil-contaminated soil.

Mechanisms of transforming growth factor-beta receptor endocytosis and intracellular sorting differ between fibroblasts and epithelial cells

Transforming growth factor-betas (TGF-beta) are multifunctional proteins capable of either stimulating or inhibiting mitosis, depending on the cell type. These diverse cellular responses are caused by stimulating a single receptor complex composed of type I and type II receptors. Using a chimeric receptor model where the granulocyte/monocyte colony-stimulating factor receptor ligand binding domains are fused to the transmembrane and cytoplasmic signaling domains of the TGF-beta type I and II receptors, we wished to describe the role(s) of specific amino acid residues in regulating ligand-mediated endocytosis and signaling in fibroblasts and epithelial cells. Specific point mutations were introduced at Y182, T200, and Y249 of the type I receptor and K277 and P525 of the type II receptor. Mutation of either Y182 or Y249, residues within two putative consensus tyrosine-based internalization motifs, had no effect on endocytosis or signaling. This is in contrast to mutation of T200 to valine, which resulted in ablation of signaling in both cell types, while only abolishing receptor down-regulation in fibroblasts. Moreover, in the absence of ligand, both fibroblasts and epithelial cells constitutively internalize and recycle the TGF-beta receptor complex back to the plasma membrane. The data indicate fundamental differences between mesenchymal and epithelial cells in endocytic sorting and suggest that ligand binding diverts heteromeric receptors from the default recycling pool to a pathway mediating receptor down-regulation and signaling.

Modulation of P450 CYP3A4-dependent metabolism by P-glycoprotein: implications for P450 phenotyping

Some compounds used for phenotyping of cytochrome P450s are substrates of P-glycoprotein (pgp). It is likely that in these cases, the level of pgp modulates the metabolism of in vivo probes. To address this important issue, we have analyzed the effects of pgp on CYP3A4-mediated reactions in two newly established cell lines (3A4/HR/MDR(-) and 3A4/HR/MDR(+)), which express CYP3A4 in the absence and presence of pgp, respectively. In cultured cells, the presence of pgp increased the apparent K(m) for the 6beta-hydroxylase activity of CYP3A4 toward testosterone and cortisol by a factor of 1.7 and 4, respectively. These steroids are poor and good substrates of pgp, respectively, and cortisol 6beta-hydroxylase has been frequently used as an in vivo probe for CYP3A4. Interestingly, we also found that pgp modulated the inhibition of CYP3A4-mediated metabolism by several compounds in intact cells. Although quinidine inhibited testosterone 6beta-hydroxylase activity in membranes or in intact cells that expressed recombinant CYP3A4 in the absence of pgp, low concentrations of this compound increased CYP3A4 activity in intact cells that expressed pgp. These results imply that pharmacokinetic drug-drug interactions involving CYP3A4 can be influenced by pgp.

[Prolapse of the urethral mucosa in young girls from the Ivory Coast]

In this retrospective study covering a nine-year period, 65 cases have been analyzed of prolapse of the urethral mucosa in young girls (aged between six weeks and 14 years) from the Ivory Coast. The aim of this study was to describe the etiology of this disorder, and to demonstrate the utility of ambulatory surgery. The main reason for the detection of this disorder was mild genital hemorrhage in 37 cases, which was related to rape in eight instances and to other types of trauma in nine cases, thereby raising serious medico-legal problems. Various forms of treatment were used (medical and/or surgical). The medical approach consisted of antibiotic and antiinflammatory treatment, combined with a local antiseptic. Two surgical approaches were adopted, either the Doria method in which the necrosed tissue is spontaneously eliminated after three to five days, or surgical excision under general anesthesia of the prolapsed mucosa followed by seromucosal stitching. The results were satisfactory in all cases, and in the surgically operated cases no complications or recurrence were noted at one-year follow-up.

Immobilization of antibodies on ultraflat polystyrene surfaces

BACKGROUND

Functional antibody surfaces were prepared on ultraflat polystyrene surfaces by physical adsorption, and the uniform distribution of monoclonal antibodies against hepatitis B surface antigen (anti-HBs) on such surfaces and the presence of dense hepatitis B surface antigen (HBsAg) particles captured by immobilized antibodies were identified.

METHODS

A model polystyrene film was spin-coated directly onto a silicon wafer surface. Atomic force microscopy was used to directly monitor the immobilization of anti-HBs antibodies and their specific molecular interaction with HBsAg. Enzyme immunoassay was also used to characterize functional antibody surfaces.

RESULTS

A mean roughness of 2 A for areas of 25 microm(2) was produced. We found a uniform distribution of anti-HBs antibodies on ultraflat polystyrene surfaces and the presence of dense HBsAg particles bound to such anti-HBs surfaces after incubation with HBsAg.

CONCLUSIONS

This study confirmed the potential of preparing dense, homogeneous, highly specific, and highly stable antibody surfaces by immobilizing antibodies on polystyrene surfaces with controlled roughness. It is expected that such biofunctional surfaces could be of interest for the development of new solid-phase immunoassay techniques and biosensor techniques.

A novel system A isoform mediating Na+/neutral amino acid cotransport

A cDNA clone encoding a plasma membrane alanine-preferring transporter (SAT2) has been isolated from glutamatergic neurons in culture and represents the second member of the system A family of neutral amino acid transporters. SAT2 displays a widespread distribution and is expressed in most tissues, including heart, adrenal gland, skeletal muscle, stomach, fat, brain, spinal cord, colon, and lung, with lower levels detected in spleen. No signal is detected in liver or testis. In the central nervous system, SAT2 is expressed in neurons. SAT2 is significantly up-regulated during differentiation of cerebellar granule cells and is absent from astrocytes in primary culture. The functional properties of SAT2, examined using transfected fibroblasts and in cRNA-injected voltage-clamped Xenopus oocytes, show that small aliphatic neutral amino acids are preferred substrates and that transport is voltage- and Na(+)-dependent (1:1 stoichiometry), pH-sensitive, and inhibited by alpha-(methylamino)isobutyric acid (MeAIB), a specific inhibitor of system A. Kinetic analyses of alanine and MeAIB uptake by SAT2 are saturable, with Michaelis constants (K(m)) of 200-500 microm. In addition to its ubiquitous role as a substrate for oxidative metabolism and a major vehicle of nitrogen transport, SAT2 may provide alanine to function as the amino group donor to alpha-ketoglutarate to provide an alternative source for neurotransmitter synthesis in glutamatergic neurons.

Collective beam-beam effects in hadron colliders

Collective beam-beam effects in hadron colliders were studied with a strong-strong beam-beam simulation on the CERN Large Hadron Collider, including multipole field errors in the lattice and beam-beam interactions at two high-luminosity interaction points. It was found that the beam-beam interaction could result in two distinct dynamics for hadron beams: a slow beam-size growth and an unstable beam-centroid oscillation. The instability of the beam-centroid oscillation has typical characteristics of the chaotic transport, i. e., the amplitude increase of the oscillation consists of slow escape from the remnants of invariant manifolds and fast diffusion in fully developed chaotic regions. The simulation results indicate that there is a threshold of the beam-beam parameter below which no unstable beam-centroid motion was observed. The escape rate of the unstable beam-centroid motion, on the other hand, increases with the nonlinear field errors in the lattice. As the slow beam-size growth is strongly enhanced by the beam-centroid oscillation, an elimination of the centroid motion with feedback can effectively suppress the beam-size growth. No steady state of coherent beam-beam oscillation was observed.

Detoxication of vinca alkaloids by human P450 CYP3A4-mediated metabolism: implications for the development of drug resistance

Vinca alkaloids are important chemotherapeutic agents, and their pharmacokinetic properties display significant interindividual variations, possibly due to CYP3A4-mediated metabolism. We have evaluated the relevance of this metabolism for the chemotherapeutic and the toxicological properties of these drugs. Analysis was performed using Chinese hamster ovary cell lines that expressed either CYP2D6 or CYP3A4. The latter cells metabolized vinblastine with a turnover number of 0.4 min(-1), resulting in a decreased cytotoxicity of this compound. Whereas vincristine and vinblastine at a concentration of 100 nM killed more than 90% of the parental cells, more than 50 and 35%, respectively, of cells that coexpressed CYP3A4 and cytochrome P450 (P450) reductase survived these treatments. No additional increase in cytotoxicity was noted above 100 nM. Similarly, preincubation of vinblastine with bacterial membranes that contained recombinant CYP3A4 and P450 reductase decreased the cytotoxicity of vinblastine for parental Chinese hamster ovary cells. We also demonstrate that the presence of vinblastine in a coculture of cells that expressed beta-galactosidase together with cells that expressed CYP3A4 strongly selected for the latter cells, resulting in an increased level of CYP3A4 in the surviving cell population. Similarly, treatment of the human colon adenocarcinoma cell line LS174T with vinblastine selected for a cell population with higher levels of endogenous CYP3A4 as revealed by immunohistochemistry without simultaneous increase of multidrug resistance protein 1 (MDR1). This is the first evidence that tumor P450s have the potential to contribute to the development of drug resistance during chemotherapy.

Electric potential produced by a dipole in a homogeneous conducting sphere

The potential produced by a dipole in a homogeneous conducting sphere is useful in simulation study, and the current available solutions still suffer from some shortcomings. In this communication, a closed solution is developed for the precise calculation of the potential anywhere in the spherical model.

Cloning and sequencing of partial genes of hepatitis C virus genome in patients with acute hepatitis C

OBJECTIVE

To explore the etiological role of HCV in patients with acute hepatitis.

METHODS

The prevalence of HCV infection in 89 patients with acute hepatitis was investigated by analysis of HCV RNA and HCV second generation antibody. HCV RNAs extracted from the sera of 5 patients with NANB acute hepatitis, which were positive for HCV RNA, were converted to cDNA by reverse transcription with random primer and genotyping by PCR with type-specific primers. The partial genes of HCV genome were amplified. The PCR products were expressed in E. coli with p-GEM-T vector, and their nucleotide sequences were determined by dideoxynucleotide chain-termination method.

RESULTS

The incidence of hepatitis virus infection was 47. 2% in HAV, 28.1% in HBV and 15.7% in HCV, respectively. The incidence of HAV and HBV coinfection was 14.6% and the rate of non-A, non-B and non-C hepatitis was 9% in all patients. The genotype of HCV-RNA positive patients was 85.8% in HCV-II, 7.1% in HCV-III and 7. 1% in combining HCV-II/III, respectively. The partial sequence of HCV genome in 5 patients with non-A and non-B acute hepatitis was amplified and the fragment was 424 bp in accordance with original design. The homology of the sequences was 98.1%-99.5% in nucleotide acid and 97.6%-99.2% in amino acid among five isolates. The average homology was 91.9% or 94.3%-95.6% for nucleotide sequences between HCV-I or HCV-II and the 5 isolates, and 92.3%-95.8% for amino acid sequences between the 5 isolates and HCV-I or HCV-II, respectively.

CONCLUSION

HCV infection is one of the main hepatitis viruses in patients with acute hepatitis, in which the HCV-II genotype is dominant and should be paid attention to it.

[Electroencephalography inverse problem by subspace decomposition of the fourth-order cumulant matrix]

It is an important topic in electroencephalography (EEG) research to localize the EEG activity sources from the scalp recordings. In this paper, based on the fourth-order cumulant matrix, a new sub-space decomposition algorithm is proposed for the EEG inverse problem. As the second-order moments (cumulants) has the drawback of being sensitive to the noise covariance. Using the fourth-order cumulants we need not know the noise covariances, as long as the noise is Gaussian. Computer simulation study on a three-layer concentric sphere head model shows its better performance than the two-order cumulate method in depressing the spatial coherent Gaussian noise.

A clinical series of laparoscopic nephrectomy, nephroureterectomy and heminephroureterectomy in the pediatric population

PURPOSE

Laparoscopic techniques have enabled less invasive surgery in pediatric urology. We report our experience with laparoscopic nephrectomy, nephroureterectomy and heminephroureterectomy in 26 children, and evaluate our series to establish the safety and efficacy of such procedures for benign disease.

MATERIALS AND METHODS

Laparoscopic procedures were done in 15 girls and 11 boys 4 months to 11 years old (mean age 37) during a 23-month period. Laparascopic surgery consisted of nephrectomy in 14 (1 horseshoe kidney), nephroureterectomy in 6 and laparoscopic heminephroureterectomy in 6 cases.

RESULTS

Mean overall operative time for the laparoscopic procedures was 165 minutes (range 43 to 355). Blood loss was less than 5 cc in all cases and there were no intraoperative complications in our series. Overall postoperative analgesic administration during hospitalization was 0.20 mg./kg. morphine sulfate and 19 mg./kg. acetaminophen as well as 0.9 mg./kg. codeine in 6 patients who did not receive morphine. Three children were discharged home on the day of surgery, while 17, 3, 1 and 2 were discharged home on postoperative days 1, 2, 4 and 5, respectively. Cosmetic results were excellent in all cases.

CONCLUSIONS

Nephrectomy, nephroureterectomy and heminephroureterectomy may be performed for benign disease in children using laparoscopy with minimal morbidity, minimal postoperative discomfort, improved cosmesis and a short hospital stay. It may even be done as an outpatient procedure.

FKBP12 is a negative regulator of transforming growth factor-beta receptor internalization

Transforming growth factor-beta (TGF-beta) family polypeptides regulate cell growth and differentiation by binding to single pass serine/threonine kinases referred to as TGF-beta type I and II receptors. Although interaction screens have shown that the immunophilin FKBP12 interacts with TGF-beta type I receptors, the role of FKBP12 in TGF-beta receptor action is presently unclear. Using a chimeric TGF-beta receptor system, we have shown a specific enhancement of internalization when FKBP12 binding to the type I receptor was prevented with rapamycin. Moreover, although earlier studies demonstrated that type II receptor kinase activity was required for optimal internalization in mesenchymal cells, we found that rapamycin functioned downstream of the type II receptor kinase. Thus, rather than modulating TGF-beta signaling, our data suggest a novel role for FKBP12 as a negative regulator of TGF-beta receptor endocytosis.

Abnormal expression of hepatoma specific gamma-glutamyl transferase and alteration of gamma-glutamyl transferase gene methylation status in patients with hepatocellular carcinoma

BACKGROUND

Hepatoma specific gamma-glutamyl transferase (HS-GGT) bands were expressed in the development of hepatocellular carcinoma (HCC) and were associated with a high incidence of HCC diagnosis. The objectives of this study were to determine the levels of HS-GGT quantitatively in the sera of patients with different liver diseases. The methylational status of GGT gene CCGG sites was analyzed in hepatoma tissues.

METHODS

The HS-GGT concentrations were quantitatively analyzed in the sera of 156 HCC patients and others with liver diseases or extrahepatic tumors. In 20 hepatoma tissues, the GGT enzyme proteins were purified, the activities of GGTs of different molecular form were examined, total RNAs were extracted and amplified by using a nested polymerase chain reaction (PCR) assay, and the methylational status of CCGG site (M3) in the 5'-noncoding region of GGT genes was investigated with the restriction enzyme Hpa II.

RESULTS

Total GGT activities in patients with liver diseases and extrahepatic tumors were abnormally increased. The levels of serum HS-GGT were significantly elevated (P < 0.001) in the HCC group; the incidence of HS-GGT over 5.5 IU/L was 86% in HCC patients and less than 3% in patients with other diseases. From liver cancer to distal noncancerous tissues, an increasing tendency (P < 0.05) of total RNA concentrations was found; the frequencies of amplified fragment and hypomethylated M3 site of GGT genes were 100% and 75% in HCC, 85% and 55% in paracancerous tissues, and 75% and 50% in noncancerous tissues, respectively. An inverse correlation was found between methylational degrees of GGT genes and expression levels of GGT.

CONCLUSIONS

The abnormal alteration of serum HS-GGT level is a sensitive tumor marker for HCC diagnosis or differentiation, and the overexpression of GGT in HCC may be related to the hypomethylational status of CCGG sites of GGT genes.

Abnormal expression of hepatoma specific gamma-glutamyl transferase and alteration of gamma-glutamyl transferase gene methylation status in patients with hepatocellular carcinoma

BACKGROUND

Hepatoma specific gamma-glutamyl transferase (HS-GGT) bands were expressed in the development of hepatocellular carcinoma (HCC) and were associated with a high incidence of HCC diagnosis. The objectives of this study were to determine the levels of HS-GGT quantitatively in the sera of patients with different liver diseases. The methylational status of GGT gene CCGG sites was analyzed in hepatoma tissues.

METHODS

The HS-GGT concentrations were quantitatively analyzed in the sera of 156 HCC patients and others with liver diseases or extrahepatic tumors. In 20 hepatoma tissues, the GGT enzyme proteins were purified, the activities of GGTs of different molecular form were examined, total RNAs were extracted and amplified by using a nested polymerase chain reaction (PCR) assay, and the methylational status of CCGG site (M3) in the 5'-noncoding region of GGT genes was investigated with the restriction enzyme Hpa II.

RESULTS

Total GGT activities in patients with liver diseases and extrahepatic tumors were abnormally increased. The levels of serum HS-GGT were significantly elevated (P < 0.001) in the HCC group; the incidence of HS-GGT over 5.5 IU/L was 86% in HCC patients and less than 3% in patients with other diseases. From liver cancer to distal noncancerous tissues, an increasing tendency (P < 0.05) of total RNA concentrations was found; the frequencies of amplified fragment and hypomethylated M3 site of GGT genes were 100% and 75% in HCC, 85% and 55% in paracancerous tissues, and 75% and 50% in noncancerous tissues, respectively. An inverse correlation was found between methylational degrees of GGT genes and expression levels of GGT.

CONCLUSIONS

The abnormal alteration of serum HS-GGT level is a sensitive tumor marker for HCC diagnosis or differentiation, and the overexpression of GGT in HCC may be related to the hypomethylational status of CCGG sites of GGT genes.

Abnormal expression of hepatoma specific gamma-glutamyl transferase and alteration of gamma-glutamyl transferase gene methylation status in patients with hepatocellular carcinoma

BACKGROUND

Hepatoma specific gamma-glutamyl transferase (HS-GGT) bands were expressed in the development of hepatocellular carcinoma (HCC) and were associated with a high incidence of HCC diagnosis. The objectives of this study were to determine the levels of HS-GGT quantitatively in the sera of patients with different liver diseases. The methylational status of GGT gene CCGG sites was analyzed in hepatoma tissues.

METHODS

The HS-GGT concentrations were quantitatively analyzed in the sera of 156 HCC patients and others with liver diseases or extrahepatic tumors. In 20 hepatoma tissues, the GGT enzyme proteins were purified, the activities of GGTs of different molecular form were examined, total RNAs were extracted and amplified by using a nested polymerase chain reaction (PCR) assay, and the methylational status of CCGG site (M3) in the 5'-noncoding region of GGT genes was investigated with the restriction enzyme Hpa II.

RESULTS

Total GGT activities in patients with liver diseases and extrahepatic tumors were abnormally increased. The levels of serum HS-GGT were significantly elevated (P < 0.001) in the HCC group; the incidence of HS-GGT over 5.5 IU/L was 86% in HCC patients and less than 3% in patients with other diseases. From liver cancer to distal noncancerous tissues, an increasing tendency (P < 0.05) of total RNA concentrations was found; the frequencies of amplified fragment and hypomethylated M3 site of GGT genes were 100% and 75% in HCC, 85% and 55% in paracancerous tissues, and 75% and 50% in noncancerous tissues, respectively. An inverse correlation was found between methylational degrees of GGT genes and expression levels of GGT.

CONCLUSIONS

The abnormal alteration of serum HS-GGT level is a sensitive tumor marker for HCC diagnosis or differentiation, and the overexpression of GGT in HCC may be related to the hypomethylational status of CCGG sites of GGT genes.

Abnormal expression of hepatoma specific gamma-glutamyl transferase and alteration of gamma-glutamyl transferase gene methylation status in patients with hepatocellular carcinoma

BACKGROUND

Hepatoma specific gamma-glutamyl transferase (HS-GGT) bands were expressed in the development of hepatocellular carcinoma (HCC) and were associated with a high incidence of HCC diagnosis. The objectives of this study were to determine the levels of HS-GGT quantitatively in the sera of patients with different liver diseases. The methylational status of GGT gene CCGG sites was analyzed in hepatoma tissues.

METHODS

The HS-GGT concentrations were quantitatively analyzed in the sera of 156 HCC patients and others with liver diseases or extrahepatic tumors. In 20 hepatoma tissues, the GGT enzyme proteins were purified, the activities of GGTs of different molecular form were examined, total RNAs were extracted and amplified by using a nested polymerase chain reaction (PCR) assay, and the methylational status of CCGG site (M3) in the 5'-noncoding region of GGT genes was investigated with the restriction enzyme Hpa II.

RESULTS

Total GGT activities in patients with liver diseases and extrahepatic tumors were abnormally increased. The levels of serum HS-GGT were significantly elevated (P < 0.001) in the HCC group; the incidence of HS-GGT over 5.5 IU/L was 86% in HCC patients and less than 3% in patients with other diseases. From liver cancer to distal noncancerous tissues, an increasing tendency (P < 0.05) of total RNA concentrations was found; the frequencies of amplified fragment and hypomethylated M3 site of GGT genes were 100% and 75% in HCC, 85% and 55% in paracancerous tissues, and 75% and 50% in noncancerous tissues, respectively. An inverse correlation was found between methylational degrees of GGT genes and expression levels of GGT.

CONCLUSIONS

The abnormal alteration of serum HS-GGT level is a sensitive tumor marker for HCC diagnosis or differentiation, and the overexpression of GGT in HCC may be related to the hypomethylational status of CCGG sites of GGT genes.

Cloning and functional identification of a neuronal glutamine transporter

Glutamine is the preferred precursor for the neurotransmitter pool of glutamate, the major excitatory transmitter in the mammalian central nervous system. We have isolated a complementary DNA clone (designated GlnT) encoding a plasma membrane glutamine transporter from glutamatergic neurons in culture, and its properties have been examined using the T7 vaccinia system in fibroblasts. When GlnT is transfected into CV-1 cells, L-glutamine is the preferred substrate. Transport is Na(+)-dependent and inhibited by alpha-methylaminoisobutyric acid, a specific inhibitor of neutral amino acid transport system A. Kinetic analysis of glutamine uptake by GlnT is saturable, with a Michaelis constant (K(m)) of 489 +/- 88 microM at pH 7.4. Glutamine uptake mediated by GlnT is pH-sensitive with a 5-fold greater efficiency of uptake at pH 8.2 than at pH 6.6. Only the maximal velocity of transport increases without a significant change in K(m). The distribution of GlnT mRNA and protein in the central nervous system is widespread and is expressed on neurons that use glutamate as their neurotransmitter. In cultured cerebellar granule cells, GlnT is expressed only on neurons and is absent from astrocytes. GlnT expression increases concomitantly with the morphologic and functional differentiation of these cells in vitro, consistent with its role of supplying glutamatergic neurons with their neurotransmitter precursor. GlnT is the first member of the system A family of neutral amino acid transporters with 11 putative membrane-spanning domains and is a potential target to modulate presynaptic glutamatergic function.

[A simplified six-item checklist for screening of fragile X syndrome]

OBJECTIVE

To investigate whether a simplified six-item checklist could be developed to improve the screening fragile X syndrome test result.

METHODS

Nine clinical characteristics were selected from patient records of 190 male and 18 female pediatrics for fragile X screening test were analyzed. The characteristics included mental retardation, family history of mental retardation, elongated face, large or prominent ears, attention deficit hyperactivity disorder, Autistic-like behavior, simian crease, macroorchidism, and hyperextensible joints.

RESULTS

Seven cases were diagnosed with fragile X syndrome by Southern analysis on PCR product. Among the nine characteristics, simian crease, macroorchidism, and hyperextensible joints were eliminated, because of low frequency and statistical insignificance. Using remaining six-item clinical checklist, if a score of 6 or more was used as the criteria for screening fragile X test, about 60% of this test in our cases could have been eliminated clinically without missing any positive cases. Thereby the proportion of case with positive results improved 8.8%.

CONCLUSIONS

With our simplified six-item clinical checklist, 60% of testing could have been eliminated clinically, thereby improving the effectiveness of fragile X screening test and promoting the proportion of cases with positive results in two groups.

[Experimental study on value of carcino-embryonic gama-glutamyl transferase isoenzymes for monitoring carcinogenesis of hepatocytes]

OBJECTIVE

To explore the value of gama-glutamyl transferase (GGT) abnormal expression in monitoring carcinogenesis of hepatocytes.

METHODS

The kinetic alterations of rat (SD) liver pathology, enzymatic histochemistry, total RNA levels, different molecular form GGT and its isoenzymes were investigated on experimental hepatomas inducing with 0.05% 2-fluoenylacetamide (2-FAA).

RESULTS

The GGTs of livers were overexpressed during canceration, liver GGT specific activities (U/g) including soluble and membrane-combined GGT activities of each group in experiment rats were significantly higher (q=4.90, P<0.01) than those of control group. The total RNA concentration was highly positively correlated with liver GGT specific activities or serum GGT activities (r=0.90, r=0.79, P<0.01). The mixed isoenzyme patterns of control rats' and embryo rats' GGT were found in sera and livers of experimental rats, the carcino-embryonic GGT bands can be detected at early stages of rat hepatocyte canceration.

CONCLUSIONS

The present data suggest that GGT is a sensitive enzyme for carcinogenesis of hepatocytes, the analysis of carcino-embryonic GGT is a useful marker for early diagnosis of rat hepatoma.

Features of cortically evoked swallowing in the awake primate (Macaca fascicularis)

Although the cerebral cortex has been implicated in the control of swallowing, the output organization of the cortical swallowing representation, and features of cortically evoked swallowing, remain unclear. The present study defined the output features of the primate "cortical swallowing representation" with intracortical microstimulation (ICMS) applied within the lateral sensorimotor cortex. In four hemispheres of two awake monkeys, microelectrode penetrations were made at </=1-mm intervals, initially within the face primary motor cortex (face-MI), and subsequently within the cortical regions immediately rostral, lateral, and caudal to MI. Two ICMS pulse trains [35-ms train, 0.2-ms pulses at 333 Hz, </=30 microA (short train stimulus, T/S); 3- to 4-s train, 0.2-ms pulses at 50 Hz, </=60 microA (continuous stimulus, C/S)] were applied at </=500-micron intervals along each microelectrode penetration to a depth of 8-10 mm, and electromyographic (EMG) activity was recorded simultaneously from various orofacial and laryngeal muscles. Evoked orofacial movements, including swallowing, were verified by EMG analysis, and T/S and C/S movement thresholds were determined. Effects of varying ICMS intensity on swallow-related EMG properties were examined by applying suprathreshold C/S at selected intracortical sites. EMG patterns of swallows evoked from various cortical regions were compared with those of natural swallows recorded as the monkeys swallowed liquid and solid material. Results indicated that swallowing was evoked by C/S at approximately 20% of 1,569 intracortical sites where ICMS elicited an orofacial motor response in both hemispheres of the two monkeys, typically at C/S intensities </=30 microA. In contrast, swallowing was not evoked by T/S in either monkey. Swallowing was evoked from four cortical regions: the ICMS-defined face-MI, the face primary somatosensory cortex (face-SI), the region lateral and anterior to face-MI corresponding to the cortical masticatory area (CMA), and an area >5 mm deep to the cortical surface corresponding to both the white matter underlying the CMA and the frontal operculum; EMG patterns of swallows elicited from these four cortical regions showed some statistically significant differences. Whereas swallowing ONLY was evoked at some sites, particularly within the deep cortical area, swallowing was more frequently evoked together with other orofacial responses including rhythmic jaw movements. Increasing ICMS intensity increased the magnitude, and decreased the latency, of the swallow-related EMG burst in the genioglossus muscle at some sites. These findings suggest that a number of distinct cortical foci may participate in the initiation and modulation of the swallowing synergy as well as in integrating the swallow within the masticatory sequence.