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.

[Relationship between methylation status of gamma-glutamyl transpeptidase (GGT) genes and abnormal expression of its enzyme proteins in tissues of human hepatomas]

OBJECTIVE

To explore the mechanism of expression and alteration of gamma-glutamyl transpeptidase (GGT) genes during the development of human hepatomas.

METHODS

The total GGT protein and total RNA were purified in human hepatomas, adjacent paracancerous and distal cancerous tissues. The specific activities of total GGT, membrane-combine GGT and soluble GGT were investigated, the GGT gene of 5'-NC region was amplified by using a nest RT-PCR assay, and methylation status of GGT gene M3 site were analyzed in the present study.

RESULTS

An increasing tendency (P < 0.05) of total RNA concentrations was found from cancer in distal cancerous tissues; the specific activities (U/g) of total GGT, membrane-combine GGT and soluble GGT were significantly higher (P < 0.05) in hepatomas than those in adjacent paracancerous or and that distal cancerous tissues; and the frequencies of amplified fragment and hypomethylated M3 site of GGT 5'-NC region genes were 100% and 75% in hepatomas, 85% and 55% in adjacent cancerous, and 75% and 50% in distal cancerous tissues, respectively.

CONCLUSIONS

The present data suggest that the abnormal expression of GGT proteins in hepatomas was related to hypomethylation status of GGT genes, and that the fragment analysis of the GGT genes might be a sensitive assay to monitor the hepatic cell canceration.

Merits and limitations of recombinant models for the study of human P450-mediated drug metabolism and toxicity: an intralaboratory comparison

A wide variety of pharmacological and toxicological properties of drugs are determined by cytochrome P450-mediated metabolism. Characterization of these pathways and of the P450 isoenzymes involved constitutes an essential part of drug development. Similarly, because P450s are catalyzing the toxication and detoxication of environmental pollutants, an understanding of these reactions facilitates risk assessment in environmental toxicology. Recently, a variety of recombinant expression systems has been employed to study the role of human P450s in these reactions. These include insect, bacterial, yeast, and mammalian models. As these were developed and characterized by different laboratories, evaluation of their merits and limitations is inherently difficult. To resolve this problem, we have established and characterized the latter three systems and present the key results here. In general, the catalytic properties of P450 isozymes in the various models were rather similar. However, taking technical considerations into account as well as the high level of functional expression of P450s achieved in bacteria make this system ideally suited for drug metabolism research, including the generation of milligram quantities of metabolites for structural determinations. For toxicological studies, however, expression of P450s in mammalian cells was most appropriate. This is exemplified here by studies into the role of human P450s in the activation and inactivation of chemotherapeutic drugs.

Effects of functional disruption of lateral pericentral cerebral cortex on primate swallowing

Bilateral cold block of the intracortical microstimulation (ICMS)-defined swallow cortex markedly affected the ability of monkeys to carry out swallowing. Significant changes also occurred in swallow-related electromyographic (EMG) activity patterns. These findings provide further evidence that the lateral pericentral cortex plays a critical role in the initiation and regulation of swallowing in the primate.

[The expression of glutathione S-transferase pi in human ovarian cancer as an indicator of resistance to chemotherapy]

OBJECTIVE

To study the relationship between the expression of glutathione S-transferase pi (GST-pi) in cancer tissue and the chemoresistance in patients with ovarian carcinoma.

METHODS

The expression of GST-pi in 53 cases of ovarian cancer, 20 ovarian benign tumors and 17 normal controls was determined by using immunohistochemical SP method and the results were studied in correlation with some clinical and pathological data.

RESULTS

(1) Positive expression with GST-pi was demonstrated in 60.4% of malignant and 10.0% of benign ovarian tumors while the expression was negative in normal controls. (2) No significant difference for the expressions was shown in relation to the histopathology, the clinical staging and the size of residual tumors after cytoreductive surgery. (3) The positive rate of the expression was 47.2% (17/36) for the initially treated patients while those with tumor recurrence had a positive rate of 88.2% (15/17). (4) GST-pi positive cases showed less response rate of 37.5% (12/32) to chemotherapy as compared with that of 76.2%(16/21) for GST-pi negative cases. (5) The survival period of the patients with GST-pi positive expression was shorter than that of those with GST-pi negative expression.

CONCLUSION

The expression of GST-pi in patients with ovarian carcinoma in closely related to the chemosensitivities clinically. Determinations of the GST-pi are useful for predicting the chemosensitivities and the prognosis of the disease.

High levels of recombinant CYP3A4 expression in Chinese hamster ovary cells are modulated by coexpressed human P450 reductase and hemin supplementation

Expression of recombinant cytochrome P450s (P450s) in mammalian cells has been used as a powerful tool to study these enzymes. However, the activity of CYP3A4 expressed in several stable mammalian cell lines was much lower than native enzyme in human liver. The low level of recombinant CYP3A4 may have been due to the low copy number of the cDNA. In addition, the low activity is caused by the low level of P450 reductase in these cells. To achieve high levels of CYP3A4 expression, we employed gene amplification of the CYP3A4 cDNA in Chinese hamster ovary (CHO) cells followed by transfection of the P450 reductase cDNA. Using this strategy, we have obtained a cell line, designated D3A4, with high levels of recombinant CYP3A4. The content of spectrally active P450 was 14 pmol/mg total cellular protein. Hemin treatment increased the P450 content 2-fold. Upon coexpression of P450 reductase in DHR/3A4 cells, enzyme activity of CYP3A4 was stimulated 15-fold, despite a 40% decrease in spectrally active P450. Interestingly, the latter effect was not due to a decrease in CYP3A4 mRNA. Treatment of these cells with hemin, however, counteracted the P450 reductase-mediated decrease of spectrally active P450. These data demonstrate that P450 reductase has a strong influence on the levels of recombinant P450 holoenzyme, possibly by modulating the level of heme in CHO cells. Concomitantly our results show that the gene amplification strategy provides a powerful approach to obtain a high level of functional recombinant P450.

MHC class I and II expression in prostate carcinoma and modulation by interferon-alpha and -gamma

BACKGROUND

Expression of Major Histocompatibility Complex (MHC) class I and II antigens are critical for the cellular immune response. Loss of MHC expression represents one mechanism by which cancer cells escape immune recognition.

PURPOSE

To define MHC class I and II expression by prostate cancer (PCa) in vivo and in vitro and the ability to modulate MHC expression in vitro with IFN-alpha and -gamma.

METHODS

Frozen tissue sections of 25 benign prostatic hyperplasia (BPH) and 18 PCa specimens were studied by immunohistochemistry. PCa cell lines LNCaP, PC-3, and DU-145 were studied by FACS, ELISA, and cytospin. Class I was detected by monoclonal antibody (mAb) W6/32, and class II by mAb 13.17. The effects of IFN-alpha and -gamma were assessed by testing the three cell lines in the presence or absence of varying concentrations of the cytokine for varying incubation times.

RESULTS

Class I was strongly expressed by 24/25 BPH specimens; 4/18 (22%) PCa were homogeneously class I-positive, while 5/18 (28%) were heterogeneously positive and 9/18 (50%) were class I-negative. PC-3 and DU-145 expressed normal levels of class I, while LNCaP expressed only low levels. All line except LNCaP demonstrated significant up-regulation of class I with either IFN-alpha or -gamma. Class II expression was not seen in BPH epithelium nor in 17/18 PCa. Class II could be only weakly induced in the three PCa lines.

CONCLUSIONS

These findings confirm prior studies demonstrating that class I expression is commonly lost or diminished in PCa. In addition, class II up-regulation by IFN-gamma appears very limited in relation to other normal or neoplastic epithelium.

IMPLICATIONS

The present findings, taken together with previous studies, are most consistent with the expression of neoantigens by PCa, which are recognized and appropriately eliminated by the cellular immune system. This selective pressure favors outgrowth of cells which down-regulate or lose class I and/or class II expression. Understanding PCa immunobiology will help in the development of effective immunotherapy for this disease.

Characterization of an esophagocardiovascular reflex in the rat

A cardiovascular reflex evoked by esophageal distension (ECR) in urethan-anesthetized male Sprague-Dawley rats was studied to 1) determine whether the relevant sensory input from the esophagus is conveyed by vagal and/or spinal afferents and 2) evaluate the effects and sites of action of antinociceptive agents. Esophageal distension evoked a rise in arterial blood pressure and heart rate that increased linearly with the log of inflation pressure (25-150 mmHg). Distension (100 mmHg for 20 s) of the lower esophagus was a more effective stimulus than distension of the upper esophagus. The ECR was attenuated by unilateral and abolished by bilateral cervical vagotomy and dose dependently inhibited by morphine (1.0-4.0 mg/kg iv) or by intrathecal (T4-T5) administration of dexmedetomidine (DX, 0.05-0.5 microgram), but not by intrathecal (T4-T5) morphine (4-16 micrograms) or intrathecal (L1-L2) or intravenous DX (0.05-0.5 microgram). The ECR was also inhibited by capsaicin and by the topical administration of DX or morphine to the solitary complex. The pressor response persisted after intravenous pancuronium, scopolamine, and methscopolamine. The ECR circuit appears to consist of vagal afferents, efferent sympathetic preganglionic pathways originating in the thoracic spinal cord, and bulbospinal neurons yet to be identified. This reflex fulfills some criteria of a nociceptive event, but this interpretation requires further investigation.

Do arterial phase helical CT images improve detection or characterization of colorectal liver metastases?

Our goal was to determine if arterial phase images from dual phase helical CT improve either the detection or the characterization of hepatic metastases in patients with colorectal carcinoma. Sixty-two patients with known colorectal cancer underwent 65 dual phase helical CT examinations to evaluate for possible liver metastases. Three blinded reviewers independently evaluated the portal venous phase images alone to determine if hepatic metastases were present or absent. Arterial phase images were then analyzed to determine if they identified additional lesions or aided in characterizing small hepatic lesions. Scores of the two methods for diagnosing metastases were compared with the "gold standard" established by a consensus panel of three other radiologists who reviewed all images together with clinical, pathologic, and other imaging data. The addition of arterial phase imaging did not detect any new metastases. However, in 6 of the 64 technically adequate examinations, hepatic arterial phase images increased lesion conspicuity and significantly increased diagnostic confidence when compared with portal vein phase scans alone. In patients with colorectal cancer, the addition of arterial phase imaging does not increase sensitivity, but improves the specificity in diagnosing liver metastases in a small number of cases. Dual phase helical CT does not appear to be indicated in the evaluation of liver metastases from colorectal cancer.

[The application of otoacoustic emissions in paediatric hearing screening]

We conducted auditory test of 132 high risk infants by using both otoacoustic emissions (OAE) and auditory brainstem response (ABR) screening. The result showed that the passing rate was 88.3% (233/264 ears) for OAE and 92% (243/264 ears) for ABR. The sensitivity and specificity of OAE in comparison to ABR were 90.5% (19/21 ears) and 95% (230/243 ears) respectively. The mean test time was 3 min for OAE and 30 min for ABR. We therefore conclude that OAE is a highly sensitive, reliable and convenient method to be used for paediatric hearing screening.

[A stereologic study on the influence of stent tube pressure on bilio-intestinal anastomotic scar formation]

Biliary tract injury results often in biliary scar stricture causing obstructive jaundice and biliary cirrhosis. Choledocho-jejunostomy with tube stent is the routine to prevent anastomotic stenosis, but how long the stent tube should be in place is controversial and little is known on the influence of the stent tube on anastomotic scar formation. In canine experimental models, bili-intestinal scar was sampled 3 weeks, 3, 6, 9 and 12 months after anastomosis for ultrastructure stereologic image analysis. It was found that the internal pressure of the stent tube exerting on anastomotic stoma inhibits scar formation, and the stent tube should be remained inside the stoma for not less than 9 months.

Subacute sclerosing panencephalitis in an infant: diagnostic role of viral genome analysis

Subacute sclerosing panencephalitis (SSPE) is related to "defective" measles virus or vaccination, though an association with parainfluenza viruses has been reported. SSPE is characterized by a slow, erratic course and elevated cerebrospinal fluid measles titers. An immunocompetent, vaccinated infant, with onset of symptoms in parainfluenza virus season and a catastrophic course is described. Cerebrospinal fluid titers were negative, but postmortem brain had typical SSPE lesions. Patient brain-derived RNA, subjected to reverse transcription followed by polymerase chain reaction yielded polymerase chain reaction products with measles virus but not parainfluenza virus genes. The sequenced fragment revealed multiple mutations, typical for SSPE. SSPE can thus present in infants, with short latency and no cerebrospinal fluid antibodies. Viral genomic analysis may be diagnostic, permitting early therapy.

Two regions within the human IL-2 gene promoter are important for inducible IL-2 expression

We have examined regulatory domains of the human IL-2 gene promoter by transfection and transient expression of rDNA constructs in which the chloramphenicol acetyl transferase gene shows T cell-specific inducible expression and cyclosporin A-mediated inhibition when placed downstream of 587 bp of the human IL-2 5'-flanking region. A series of 5'-deletion constructs transfected into the Jurkat T lymphoid line demonstrates that a region encompassing 370 bp 5' of the transcription start site is sufficient for inducible chloramphenicol acetyl-transferase expression. Further dissection of this region with internal deletion (linker-scanner) mutants revealed that portions of at least two discrete regions from -42 to -169 and -289 to -361 bp relative to the transcription start site are critical for inducible expression of the IL-2 gene. T cell-specific expression of wild-type and mutant IL-2 promoter constructs could be increased severalfold by the insertion of an upstream SV40 enhancer. With use of a battery of IL-2 promoter constructs, we could not identify subregions within IL-2 5'-flanking sequences which are crucial for cyclosporin A inhibition of the IL-2 gene or deletion of which resulted in loss of T cell-specific expression, suggesting that such functions may be mediated at pre-transcriptional levels.

Two regions within the human IL-2 gene promoter are important for inducible IL-2 expression

We have examined regulatory domains of the human IL-2 gene promoter by transfection and transient expression of rDNA constructs in which the chloramphenicol acetyl transferase gene shows T cell-specific inducible expression and cyclosporin A-mediated inhibition when placed downstream of 587 bp of the human IL-2 5'-flanking region. A series of 5'-deletion constructs transfected into the Jurkat T lymphoid line demonstrates that a region encompassing 370 bp 5' of the transcription start site is sufficient for inducible chloramphenicol acetyl-transferase expression. Further dissection of this region with internal deletion (linker-scanner) mutants revealed that portions of at least two discrete regions from -42 to -169 and -289 to -361 bp relative to the transcription start site are critical for inducible expression of the IL-2 gene. T cell-specific expression of wild-type and mutant IL-2 promoter constructs could be increased severalfold by the insertion of an upstream SV40 enhancer. With use of a battery of IL-2 promoter constructs, we could not identify subregions within IL-2 5'-flanking sequences which are crucial for cyclosporin A inhibition of the IL-2 gene or deletion of which resulted in loss of T cell-specific expression, suggesting that such functions may be mediated at pre-transcriptional levels.

[3H]TCP binding sites in Alzheimer's disease

Quantitative autoradiography was used to determine the density and distribution of [3H]1-[1-(2-thienyl)-cyclohexyl]piperidine ([3H]TCP) binding sites in human hippocampal tissue sections from control and Alzheimer's disease patients. Some Alzheimer's cases showed no changes in binding site density while other cases showed substantial declines in the CA1 region. [3H]TCP binding in the CA1 region from Alzheimer's patients was reduced an average of 40% while the other hippocampal regions were unaffected. It is proposed that the loss of [3H]TCP sites in the hippocampal CA1 region of certain Alzheimer's cases is associated with the greater cell loss observed in cases of severe Alzheimer's disease.

Antigenic changes in gp70 associated with the adult variant of Gross murine leukemia virus, WB91

Gross murine leukemia virus (GV) is not leukemogenic in adult mice whereas a variant of GV, WB91, is highly leukemogenic regardless of the age of the inoculated animal. FACS and SDS-PAGE analysis have demonstrated that these viruses differ at least with respect to the env-encoded gp70 molecule. FACS analysis of virus infected or virus transformed cells with a type specific monoclonal antibody (mAb #55) indicated a difference in determinants associated with gp70 expressed by the two viruses. Rat antisera raised against GV- or WB91-induced tumor cells demonstrated that there were no crossreactive determinants between the gp70 molecules expressed on these tumor cells as recognized by the rat antisera. This difference in the gp70 molecules encoded by WB91 and GV may account for the ability of the WB91 virus to induce leukemia in adult mice, possibly by affecting the immunogenicity of the virus.

L-[3H]Glutamate binds to kainate-, NMDA- and AMPA-sensitive binding sites: an autoradiographic analysis

The anatomical distribution of L-[3H]glutamate binding sites was determined in the presence of various glutamate analogues using quantitative autoradiography. The binding of L-[3H]glutamate is accounted for by the presence of 3 distinct binding sites when measured in the absence of Ca2+, Cl- and Na+ ions. The anatomical distribution and pharmacological specificity of these binding sites correspond to that reported for the 3 excitatory amino acid binding sites selectively labelled by D-[3H]2-amino-5-phosphonopentanoate (D-[3H]AP5), [3H]kainate ([3H]KA) and [3H] alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid ([3H]AMPA) which are thought to be selective ligands for the N-methyl-D-aspartate (NMDA), KA and quisqualate (QA) receptors, respectively.

Autoradiography of D-2-[3H]amino-5-phosphonopentanoate binding sites in rat brain

Quantitative autoradiographic techniques were used to obtain a preliminary description of the pharmacological characteristics and anatomical distribution of the selective N-methyl-D-aspartate (NMDA) receptor antagonist D-2-[3H]amino-5-phosphonopentanoate (D-[3H]AP5). Binding sites exhibit the appropriate pharmacological profile and are found throughout the brain. Consistent with ligand binding experiments using purified synaptic membranes, the hippocampus has the highest levels of binding. Within this structure, the binding site distribution is indistinguishable from that obtained for D-AP5-sensitive L-[3H]glutamate binding sites; highest levels are found within the stratum radiatum, a region in which NMDA receptors are involved in the formation of long-term potentiation.

Distribution of [3H]AMPA binding sites in rat brain as determined by quantitative autoradiography

Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) is a potent neuroexcitatory compound which acts at the quisqualate class of excitatory amino acid receptors. In this study we describe the pharmacological characteristics and anatomical distribution of [3H]AMPA binding sites in rat brain using quantitative autoradiography. These binding sites exhibit the appropriate pharmacological characteristics and are found in high concentrations in the hippocampus, cerebral cortex (especially layers I-III), induseum griseum, and dorsal lateral septum. Intermediate concentrations are found in the corpus striatum and deeper layers of cerebral cortex. Lower concentrations are found in the diencephalon, midbrain and brainstem. These results demonstrate that [3H]AMPA binding sites are found throughout the CNS and suggest brain regions which may use quisqualate receptors as glutamate neurotransmitter receptors.