Induction of 8-hydroxydeoxyguanosine in DNA by chromium(III) plus hydrogen peroxide and its prevention by scavengers

The capability of Cr(III) to induce DNA lesions generated by oxidative damage was investigated in this study by examining the formation of 8-hydroxydeoxyguanosine (8-OHdG) in calf thymus DNA by CrCl3 and/or H2O2 in 10 mM phosphate buffer. In the presence of 0.5 mM H2O2, the formation of 8-OHdG markedly increased with increasing CrCl3 concentration. In contrast, H2O2 or CrCl3 alone did not cause any increase in 8-OHdG level above background. The amount of 8-OHdG induced by CrCl3 plus H2O2 was time dependent; its generation increased linearly over an incubation period of 90 min. The formation of 8-OHdG was unfavorable in an acidic solution (pH < 6); the highest level of 8-OHdG was observed at pH 7-8. Scavengers of reactive oxygen species markedly inhibited the formation of 8-OHdG by CrCl3 plus H2O2; the inhibition effect was sodium azide > D-mannitol > Tris-HCl at an equal concentration. The induction of 8-OHdG by CrCl3 plus H2O2 remained unchanged in D2O. Moreover, an addition of catalase (2.2 U/ml) to the reaction mixture completely inhibited the formation of 8-OHdG by CrCl3/H2O2, whereas only 22% of that formation was inhibited by superoxide dismutase (11 U/ml). A large amount of bovine serum albumin (1.1 mg/ml) could reduce the formation of 8-OHdG by CrCl3 plus H2O2, thereby implying that Cr(III)-mediated DNA-protein crosslinks are unfavorable for 8-OHdG formation. Furthermore, ascorbate could prevent the formation of 8-OHdG by CrCl3 plus H2O2; the extent of prevention increased with increasing ascorbate concentration (10 microM-3 mM). Thus, ascorbate acts as a free radical scavenger in the CrCl3/H2O2 system. The above findings suggest that Cr(III)/H2O2 could generate oxidative damage to DNA, possibly through a Fenton-like reaction, i.e. Cr(III)+H2O2-->Cr(IV)+.OH+OH-. This study also indicates that Cr(III), previously considered as the ultimate kinetically stable species of Cr(VI) metabolites, is capable of inducing carcinogenic lesions through interaction with a cellular oxygen species.

Oxidative damage to DNA induced by areca nut extract

In Taiwan, people chew betel quid which contains tender areca nut with husk. In other countries, people prefer ripe and dried areca nut without husk. In this study, we compared the reactive oxygen species-induced oxidative DNA damage in isolated DNA and CHO-K1 cells between treatments with tender areca nut extract (ANE) and ripe ANE. Incubation of these two ANE preparations with isolated DNA generated 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in an alkaline environment in a dose-dependent manner. Ripe ANE generated higher levels of 8-OH-dG compared to tender ANE. The addition of iron(II) (100 microM) resulted in 1.4- and 3.1-fold increases of 8-OH-dG when incubated with 1 mg/ml each of tender and ripe ANE. In testing the effect of ANE to cellular DNA, CHO-K1 cells were used for its documented sensitivity to reactive oxygen species. In CHO-K1 cells, ripe ANE was more cytotoxic than tender ANE following an 18-h incubation. The cytotoxicity to CHO-K1 cells was positively correlated with the formation of 8-OH-dG following tender (r=0.97) and ripe (r=0.91) ANE treatment. Addition of the iron chelating agent o-phenanthroline (10 and 20 microM) to cells prior to ri ANE exposure significantly increased (p<0.05) the survival of CHO-K1 cells. In addition, ripe ANE induced dichlorofluorescein-mediated fluorescence which indicated the formation of hydrogen peroxide in CHO-K1 cells. In conclusion, this study demonstrated that ANE-induced oxidative damage to isolated and cellular DNA which may result from the generation of hydrogen peroxide, and iron may serve as a catalyst in this process. Furthermore, ripe ANE generated higher oxidative DNA damage levels compared to tender ANE.

Heterologous desensitization of opioid-stimulated Ca2+ increase by bradykinin or ATP in NG108-15 cells

Leucine-enkephalin (Leu-EK) dose-dependently elicited an increase in cytosolic Ca2+ concentration ([Ca2+]i) with an EC50 of 1.2 microM via the phosphoinositide cascade in NG108-15 cells. Chronic treatment of cells with [D-Ala2,D-Leu5]enkephalin caused time-dependent homologous desensitization. In the presence of extracellular Ca2+, ATP as well as bradykinin stimulated significantly higher increases in inositol 1,4,5-trisphosphate (IP3) generation than did Leu-EK; however, the magnitude of intracellular Ca2+ pools increased after ATP stimulation, whereas bradykinin depleted intracellular pools. Hence, cells lost their [Ca2+]i response to Leu-EK if bradykinin was first added to induce a [Ca2+]i increase, whereas the response was unchanged if Leu-EK was added after addition of ATP. When Leu-EK was added simultaneously with bradykinin or ATP, an additive response was observed in IP3 generation; however, the rise in [Ca2+]i reached the same level as that induced by bradykinin or ATP alone. In the absence of extracellular Ca2+ in which the replenishment of intracellular pools was not possible, ATP displayed an inhibitory effect similar to that of bradykinin on the Leu-EK-induced [Ca2+]i increase. Prior treatment of cells with Leu-EK slightly heterologously desensitized the action of bradykinin, but had no effect on the ATP response. Our results suggest that a shared intracellular Ca2+ pool is sensitive to the opioid, bradykinin and P2-purinoceptor agonists; however, a defined pool of phosphatidylinositol 4,5-bisphosphate or a specific phospholipase C is responsible for each receptor.

Establishment of in vivo hepatoma models in rat and mouse from rodent hepatoma cell lines

BACKGROUND

Hepatoma is one of the most common cancers in Southeast Asia and African countries. In Taiwan, it is the leading cause of death in male cancer patients. In order to examine the effect of various factors on the growth of hepatoma, in vivo hepatoma models such as carcinogen-induced hepatoma and subcutaneous implantation of hepatoma in nude mice have been used. However, there are disadvantages in these models.

METHODS

Rats and mice were anesthetized by ketamine or ether, respectively. After a midline incision was made, N1S1 rat hepatoma cells were injected intrasplenically to partially hepatectomized or sham-operated rats, while BALB/c mice received intrasplenic injection of ML-2 and ML-3 mouse hepatoma cells. For direct tumor implantation, a 1mm3 N1S1 tumor piece was implanted in liver of Sprague-Dawley (SD) rat using a trocar. Animals were sacrificed at specific times after tumor implantation. Tumor incidence and the number of tumor nodules on the liver surface were recorded. Tumor samples were fixed and embedded for histological examination.

RESULTS

After intrasplenic implantation of ML-2 cells, no tumor was observed on the liver in any of the 10 mice 40 days later. In comparison, rapid growth of hepatic ML-3 tumors was observed in all animals. Rat hepatoma cells RH-35, McA-RH7777 and McA-RH8994 cells did not form tumors in SD rats. The tumorigenicity of N1S1 cells in SD rats was dose-dependent on implanted tumor cells. In addition, hepatic N1S1 tumors could be obtained within a few weeks by homograft.

CONCLUSIONS

We have successfully established in vivo hepatoma models in both the rat and the mouse. The murine ML-3 cells generated hepatoma in syngeneic BALB/c mice while the tumorigenicity of N1S1 cells in partially hepatectomized SD rats was dose-dependent on implanted tumor cells. These in vivo rodent models will be valuable tools for future studies of hepatoma.

Mechanistic study of the inhibition of aflatoxin b1-induced hepatotoxicity by dimethyl 4,4'-dimethoxy-5,6,5',6'-dimethylenedioxy biphenyl-2, 2'-dicarboxylate

The mechanism of DDB (dimethyl 4,4'-dimethoxy-5,6,5',6'-dimethylenedioxy biphenyl-2,2'-dicarboxylate) prevention of aflatoxin B1 (AFB1)-induced hepatotoxicity in rats has been investigated. Pretreatment of DDB (200 mg/kg) daily for 4 days significantly suppressed (P < 0.05) the AFB1-induced hepatic damage as evidenced by the increase of serum marker enzymes. DDB induced rat hepatic cytochrome P450IA1, IIB1 and glutathione S-transferase activities. The hepatic microsomes derived from DDB treated rats increased the mutation frequency of AFB1 and enhanced the binding of AFB1 to DNA. However, the hepatic S9 fraction from DDB treated rats showed a protective effect against AFB1-induced damage. It is concluded that the protective effect of DDB against AFB1-induced damage might be mediated by the induced glutathione S-transferase activity and not from the accelerated hepatic cytochrome P450 detoxification pathway of AFB1 which was previously believed.

A phospholipase A2 inhibitor from the plasma of the South American rattlesnake (Crotalus durissus terrificus). Protein structure, genomic structure, and mechanism of action

The lethal toxicity of the South American rattlesnake (Crotalus durissus terrificus) venom can be attributed mainly to the presence of a pre-synaptic neurotoxin, crotoxin, with phospholipase A2 activity. Crotoxin is a heterodimer of an acidic protein (CA) and a basic phospholipase A2 (CB). An anti-toxic protein of subunit molecular mass 23.6 kDa that neutralizes both lethal and PLA2 activity of crotalid venom and crotoxin has been previously purified from the plasma of this snake (Fortes-Dias, C., Fonseca, B. C. B., Kochva, E., and Diniz, C. R. (1991) Toxicon 29, 997-1008). The protein has been named CNF for Crotalus neutralizing factor. In the present study, we have shown that CNF exists as an oligomeric aggregate of (CNF)n, where n = 6-8, and when it interacts with crotoxin, it replaces the acidic protein CA of crotoxin to form a stable near stoichiometric complex of CNF.CB. The CNF.CB complex no longer exhibits PLA2 activity and is inert in vivo. Thus, the exchange reaction between CA.CB of crotoxin and CNF to form CNF.CB and free CA is reminiscent of the interaction of crotoxin with its target receptor at the neuromuscular transmission site in the presynaptic cells. A cDNA encoding CNF has been isolated from a liver cDNA library using an appropriate nucleotide probe. The nucleotide sequence codes for a 19-residue signal peptide, followed by a 181-residue protein of which 16 are half-cystines. Calculated molecular mass is 20.06 kDa, and there is a putative N-linked carbohydrate site at Asn157.

C-reactive proteins, limunectin, lipopolysaccharide-binding protein, and coagulin. Molecules with lectin and agglutinin activities from Limulus polyphemus

In 1964, Levin and Bang discovered that gram-negative bacterial endotoxin could rapidly induce gelation of Limulus amebocyte lysate. This observation has led to the development of the most sensitive and specific method for the detection of bacterial endotoxin in pharmaceuticals and drugs intended for human use. Over 10 years ago, Bang injected endotoxin into young horseshoe crabs and observed a time and dose-dependent coagulation of the whole hemolymph. Limunectin, LEBP-PI, and Limulus CRP are found together with coagulin as part of the hemolymph clot at the time of endotoxin-induced exocytosis of amebocytes. In this manner, these molecules with agglutinin/lectin activities could work in concert to assist in the recognition and eventual removal of invading microorganisms from the circulating system. Although the mechanism of endotoxin-induced clot formation is to a large extent understood, the mechanism of clot dissolution and removal in the Limulus hemolymph remains to be clarified.

Flowcytometric analysis of the effect of berberine on the expression of glucocorticoid receptors in human hepatoma HepG2 cells

Berberine is an alkaloid found in many plants, including the Coptis chinensis and Arcangelisia flava. Berberine has been reported to have cytostatic effect on tumor growth. Previously, we have found that the level of glucocorticoid receptors (GR) was significantly higher in hepatoma than in adjacent liver tissues. Using human HepG2 hepatoma cells, we have found that GR were expressed not only in G0-G1 phases, but also in S and G2+M phases. The objective of the present study was to examine the effect of berberine on the expression of GR and its relation to cell cycle progression of HepG2 cells. Continuous exposure of HepG2 cells to various concentrations (1-50 microM) of berberine resulted in growth inhibition in a dose dependent manner. The viability of berberine-treated HepG2 cells was greater than 90% in all treatment groups. Flowcytometric analysis of berberine-treated HepG2 cells showed that the S phase fraction was significantly reduced. GR levels were higher in berberine-treated HepG2 cells than in vehicle (DMSO)-treated cells. In addition, the secretion of alpha-fetoprotein by HepG2 cells was inhibited by berberine. Finally, the berberine induced cell growth arrest was partially reversible in HepG2 cells.

Bacterial mutagenicity, metabolism, and DNA adduct formation by binary mixtures of benzo[a]pyrene and 1-nitropyrene

Air pollutants are a complex mixture containing polycyclic organic compounds. Among these are 1-NP and B[a]P, which are important contributors to the mutagenicity of diesel exhaust and airborne particulate matters. To investigate the interaction of a complex mixture of airborne mutagens, the mutagenicity of 1-NP was examined with S. typhimurium TA98 and TA98NR in the presence and absence of B[aP. B[a]P exhibited a more antagonistic effect on the mutagenicity of 1-NP in strain TA98 than in strain TA98NR. Also studied were (1) the inhibitory effects of B[a]P on the nitroreductive metabolism of 1-NP and (2) DNA adduct formation by 1-NP. Nitroreductase was associated with the metabolism of 1-NP, and was reduced in a dose-dependent manner in a binary mixture of 1-NP and B[a]P. HPLC analysis showed that the amounts of 1-AP and NAAP, the metabolites of 1-NP, were significantly decreased by the addition of B[a]P in mixtures. The results indicate that the antagonistic effect of B[a]P on the mutagenicity of 1-NP is mediated through altering its nitroreductive metabolism.

Analysis of glucocorticoid receptors in human hepatocellular carcinoma and HepG2 cells

Hepatocellular carcinoma is the leading cause of male cancer death in Taiwan. We have found that the level of glucocorticoid receptor in hepatocellular carcinoma is significantly higher than that in the peritumoral tissue. In this study, we used a rat liver glucocorticoid receptor complementary DNA probe to examine the expression of glucocorticoid receptor gene in 15 paired samples of hepatocellular carcinoma and their peritumoral tissues. No differences in genomic DNA patterns of the glucocorticoid receptor gene were found between the tumor and peritumoral tissues. The amount of glucocorticoid receptor was found to be significantly higher in hepatoma samples than in peritumoral liver samples. The levels of glucocorticoid receptor messenger RNAs were increased in most tumors compared with their peritumoral samples. To examine the function of glucocorticoid receptors in hepatoma, we examined the expression of glucocorticoid receptor and its relation to cell-cycle progression in human HepG2 cells. Using specific monoclonal antibodies and flow cytometric study, we found glucocorticoid receptor to be expressed constitutively in all cell-cycle phases. In addition, hydrocortisone treatment of HepG2 cells resulted in increased expression of glucocorticoid receptors and increased secretion of alpha-fetoprotein. RU-486, a glucocorticoid antagonist, blocked the hydrocortisone effect, indicating that glucocorticoid receptors are functional in HepG2 cells. Taken together, our data suggest that glucocorticoids and their receptors play an important role in the growth of hepatoma.

Aromatic DNA adducts in brain tumors by 32P-postlabeling analysis

DNA from human brain tumor samples was analysed by the 32P-postlabeling technique for the presence of aromatic DNA adducts. Thirteen out of 16 samples showed low levels of adducts at 0.14-3.53 adducts per 10(9) nucleotides. Inter-individual variations in the patterns of these aromatic adducts were observed. On the other hand, none of 5 brain samples from epilepsy patients revealed any evidence of such adducts. The data demonstrated the presence of low level, large molecule aromatic DNA adducts in malignant brain tissues and these adducts may either result from environmental exposure to an undetermined genotoxic agent or from the aging process.

Agglutination activity of Limulus polyphemus coagulogen following limited proteolysis

1. A 14 kDa protein with cell agglutination properties has been purified from endotoxin-activated L. polyphemus amebocyte lysate. Amino terminal sequence analysis indicates that this protein corresponds to a proteolytically cleaved product (coagulin) of coagulogen. 2. Similar cell agglutination activity can be generated, in vitro, by proteolytic cleavage of the coagulogen with either trypsin, endogenous protease or an alpha 2M/enzyme complex isolated from amebocytes. 3. Studies with [125I]-labeled coagulogen showed that only coagulin, not the intact coagulogen, binds to rabbit erythrocytes and formalin-fixed amebocytes. 4. The cell agglutination activity of coagulin towards erythrocytes was not inhibited by various sugars tested, and was not Ca(2+)-dependent. 5. These findings suggest that coagulogen and coagulin are reminiscent of their mammalian counterparts, fibrinogen and fibrin, in their clotting and relative adhesive properties.

Differential sensitivity of human hepatoma cell line and primary rat hepatocyte culture to benzo(a)pyrene-induced unscheduled DNA synthesis and adduct formation

We studied the genotoxic potential of a carcinogen in the human hepatoma cell line, HepG2, and in primary rat hepatocyte culture. HepG2 is a well differentiated human hepatoblastoma cell line with biotransforming capacity. Rat hepatocytes were obtained by the standard two-step in situ perfusion technique. Following benzo(a)pyrene treatment, both HepG2 and primary rat hepatocyte culture showed unscheduled DNA synthesis with different sensitivity. In 32P-postlabelling analysis, the chromatogram revealed quantitative and qualitative differences between HepG2 and primary rat hepatocyte cultures when treated with 10 microM benzo(a)pyrene for 18 hr. The results have demonstrated that the HepG2 cell line may be used in addition to primary rat hepatocytes in risk assessment for detection of environmental carcinogens.

Isolation and characterization of C-reactive protein (CRP) cDNA and genomic DNA from Xenopus laevis. A species representing an intermediate stage in CRP evolution

C-reactive protein (CRP) is a prototypic acute phase protein in human and rabbit. Although it is structurally and functionally conserved from invertebrate to human, there are species-specific differences in patterns of expression and putative function. To further investigate the biological significance, regulation, and evolution of CRP, we isolated Xenopus CRP and subsequently derived and sequenced corresponding cDNA and the genomic clones. The structure and expression of Xenopus CRP were also compared to those of the other CRPs. Analyses of the amino acid sequence and the nucleotide sequence reveal that the mature Xenopus CRP is a 222-amino acid protein preceded by a 16-residue signal peptide. During development, Xenopus CRP is expressed, only when the liver appears, and therefore is not likely to play a role in early embryonic development. Compared to other species, Xenopus CRP is present at an intermediate low level of < 1 microgram/ml in the normal serum. Unlike human and rabbit CRP, Xenopus CRP is not induced by turpentine or heatshock treatment. The heatshock consensus sequence (Woo, P., Korenberg, J. R., and Whitehead, A. S. (1985) J. Biol. Chem. 265, 4136-4142) are not present in the Xenopus CRP gene. It is suggested that Xenopus CRP represents a transitional period in CRP evolution when host defenses switched from primitive innate immunity to a much more complex immune system. The constitutive functions of CRP gradually became less essential as the result of the development of a complex immune system.

Effect of an extract from Phyllanthus amarus on hepatitis B surface antigen gene expression in human hepatoma cells

It has been suggested that Phyllanthus amarus may be helpful in the treatment of hepatitis B virus infection. We studied the effect of an aqueous extract of P. amarus on the cultured hepatoma cell line HepA2. This cell line had been transfected with tandemly arranged HBV DNA and continued to synthesize and secrete both HBsAg and HBeAg. Extract of P. amarus reversibly inhibited cellular proliferation and suppressed HBsAg production but not HBeAg production in HepA2 cells. We also found that P. amarus suppressed HBsAg gene expression at mRNA level in a time-dependent manner, and selectively abolished the HBsAg gene promoter driven CAT activity. Our results demonstrate that P. amarus contains some active components which can suppress the HBsAg gene expression in human hepatoma cells. Such suppression may contribute the antiviral activity of P. amarus in vivo.

Partially multiplexing sensor network exploiting low coherence interferometry

A partially multiplexed fiber-optic-based sensor network based on low coherence interferometry is reported for which the scanning interferometer simultaneously sweeps the coherence-matched region of each sensor. The advantage of this approach is that the signal-to-noise ratio is maximized while the cross talk between sensors is minimized. The normal requirement that each sensor must be fabricated with a different length also does not apply. The concept is demonstrated by multiplexing two bulk optic Michelson interferometers. A resolution of ~ 50 nm with an operational range of 200 microm was achieved in the prototype system.

Alpha-fetoprotein in patients with hepatocellular carcinoma after transcatheter arterial embolization

To assess the usefulness of alpha-fetoprotein (AFP) in monitoring treatment effects of transcatheter arterial embolization (TAE) in hepatocellular carcinoma (HCC) patients, a total of 31 sets of AFP levels after TAE in 21 HCC patients were analysed by linear regression between logarithmic AFP levels and days. Eleven sets of AFP data with poor linear declination were accompanied with poor TAE results except in one patient who had chronic hepatitis with acute exacerbations. Twenty sets of data with good linear declination in the first month after TAE indicated good TAE results. Seven of them showed no evidence of tumour recurrence nor elevated AFP levels within a follow-up of 6 months. The mean, standard deviation and range of half-lives of AFP in the non-recurrent group were 5.0, 1.6 and 2.9-7.2 days, respectively. The others experienced late tumour recurrence that was detected by rebound of AFP levels except one who had another non-AFP-secreting HCC. Thus, the results might be used as a reference in monitoring the treatment effects of TAE and the timing selection of repeated TAE.

Debrisoquine metabolism in Chinese patients with Alzheimer's and Parkinson's diseases

We determined the oxidative phenotype and metabolic ratio of debrisoquine in 96 Chinese patients with Alzheimer's disease (n = 12), Parkinson's disease (n = 55), and using patients with stroke and cervical spondylosis as controls (n = 29). We did not find any difference in debrisoquine metabolic phenotype among Parkinson's disease, Alzheimer's disease, and control patients as judged by chi-square analysis. In addition, the metabolic ratio of all our patients was less than 12.6. The result suggested that Chinese patients with Parkinson's disease and Alzheimer's disease metabolize debrisoquine at a velocity not different from that of their Western counterparts even though the frequency distribution of debrisoquine metabolism phenotyping in these two populations is quite different.

The cis-acting 3'-element of rubella virus RNA has DNA promoter activity

The 3'-terminal region of the rubella virus (RV) positive-strand RNA, referred to here as the cis-acting element (CAE), is implicated in the initiation of negative-strand RNA synthesis. Sequence analysis of the 3'-CAE shows that there is a putative TATA box which is surrounded by G + C-rich sequences. To determine whether this element, in a DNA form, has the capability to initiate transcription, a 3'-end 165-bp NarI-EcoRI fragment from the RV cDNA was cloned upstream from a cat reporter gene. The level of CAT activity was dependent on the presence of the 3'-CAE and the SV40 enhancer. Primer extension analysis of the CAT mRNA showed that the transcription start point is in the RV 3'-CAE, 34 bp downstream from the putative TATA box. DNA-gel shift analysis revealed that three nucleoprotein-specific complexes were formed with the 3'-CAE and the binding sites for these proteins were between bp -64 to -108. The possible promoter function of the RV 3'-CAE is discussed in context to RV persistence.

Effect of sodium butyrate on glucocorticoid-sensitive and -resistant P1798 lymphosarcoma

This study aims to examine the effect of sodium butyrate on the viability and the level of glucocorticoid receptors and cells cycle progression in glucocorticoid-sensitive and -resistant P1798 cells. Our results indicated that low levels of sodium butyrate had no effect on either the viability or the receptor level. However, high-level (5 mM) sodium butyrate appeared to reduce cell viability as well as the glucocorticoid receptor level. On the other hand, sodium butyrate inhibited cell cycle progression in a dose-dependent manner. This response was similar in both the glucocorticoid-sensitive and -resistant P1798 cells. Results from this study suggested that the sodium butyrate induced effect may be cell cycle related.

Systemic amyloidosis presenting as splenic tumor

We report a case of amyloidosis manifesting as a splenic tumor and pleural effusion. Only one case of a splenic amyloid tumor has been reported in the literature, but its radiological findings were not described. Therefore, we present the computed tomographic (CT), sonographic, and angiographic features of splenic amyloid tumor.

Analysis of monoamines in the cerebrospinal fluid of Chinese patients with Alzheimer's disease

We have established HPLC assay conditions that could measure the levels of 14 monoamines and their metabolites simultaneously. Monoamine levels in cerebrospinal fluids of 12 Chinese patients with Alzheimer's disease were compared with those in samples from patients with benign prostate hyperplasia. Of the 14 monoamines and metabolites, only three were found to be present in all samples. Although the levels of 5-hydroxy-3-indoleacetic acid (HIAA) and homovanillic acid (HVA) in cerebrospinal fluid of patients with Alzheimer's disease were lower, and the levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) higher, as compared to control patients, no significant differences were found between these two groups.

Purification and characterization of an endotoxin-binding protein with protease inhibitory activity from Limulus amebocytes

Using a lipopolysaccharide affinity column and ion exchange chromatography, a 12-kDa protein has been purified from Limulus amebocytes. In solid phase binding assays, the radiolabeled protein binds specifically to lipopolysaccharide (LPS) with a Kd value on the order of 10(-7) M. A cDNA coding for this protein has been isolated and sequenced. The amino acid sequence deduced from the cDNA indicates that this protein shares no sequence homology with LPS-binding proteins isolated from different species of vertebrates (Schumann, R. R., Leong, S. R., Flaggs, G. W., Gray, P. W., Wright, S. D., Mathison, J. C., Tobias, P. S., and Ulevitch, R. J. (1990) Science 249, 1429-1431) and invertebrates (Aketagawa, J., Miyata, T., Ohtsubo, S., Nakamura, T., Morita, T., Hayashida, H., Miyata, T., Iwanaga, S., Takao, T., and Shimonishi, Y. (1986) J. Biol. Chem. 261, 7357-7365). The binding to LPS can be displaced by the unlabeled 12-kDa protein, polymyxin B, lipid A, and to a lesser extent by D-glucosamine. In whole cell binding assays, the 12-kDa protein has also been shown to bind to Escherichia coli. Using both [14C]casein and a synthetic substrate, the protein has been shown to inhibit the proteolytic activity of trypsin, with an IC50 of approximately 10(-7) M. In the presence of LPS, the antitryptic acitivity of the Limulus endotoxin-binding protein-protease inhibitor remains unaffected. The protein is a major component of the cytoplasmic proteins (1%). Immunocytochemical analysis reveals that this protein exists in the secretory granules of the amebocytes where enzymes and substrates for the clotting cascade reside. Based on the unusual dual functional properties, the newly isolated protein was named a "Limulus endotoxin-binding protein-protease inhibitor" (LEBP-PI).

Specific binding of host cell proteins to the 3'-terminal stem-loop structure of rubella virus negative-strand RNA

At the 5' end of the rubella virus genomic RNA, there are sequences that can form a potentially stable stem-loop (SL) structure. The complementary negative-strand equivalent of the 5'-end SL structure of positive-strand rubella virus RNA [5' (+) SL structure] is thought to serve as a promoter for the initiation of positive-strand synthesis. We screened the negative-strand equivalent of the 5' (+) SL structure (64 nucleotides) and the adjacent region of the negative-strand RNA for their ability to bind to host cell proteins. Specific binding to the 64-nucleotide-long potential SL structure of three cytosolic proteins with relative molecular masses of 97, 79, and 56 kDa was observed by UV-induced covalent cross-linking. There was a significant increase in the binding of the 97-kDa protein from cells upon infection with rubella virus. Altering the SL structure by deleting sequences in either one of the two potential loops abolished the binding interaction. The 56-kDa protein also appeared to bind specifically to an SL derived from the 3' end of positive-strand RNA. The 3'-terminal structure of rubella virus negative-strand RNA shared the same protein-binding activity with similar structures in alphaviruses, such as Sindbis virus and eastern equine encephalitis virus. A possible role for the host proteins in the replication of rubella virus and alphaviruses is discussed.

Hormonal therapy for hepatocellular carcinoma

Hepatocellular carcinoma is not only the leading cause of male cancer death in Taiwan, but also one of the most common cancers in the world. The survival of hepatocellular carcinoma patients is very low, mainly due to the lack of effective treatments. Radiation and chemotherapies in general are not satisfactory: surgery itself is the most effective treatment for hepatocellular carcinoma but only on small resectable tumors. The overall prognosis is still poor. Previously, we have found that the level of glucocorticoid receptor and its mRNA in hepatocellular carcinoma was significantly higher than that of the adjacent liver tissue. This correlated well with the elevated serum alpha-fetoprotein levels in patients with hepatocellular carcinoma. Recently, a female hormone, progesterone, has been found to inhibit the expression of alpha-fetoprotein in hepatoma cells. In addition, progesterone has been used to treat a few hepatocellular carcinoma patients with promising responses. These results together with our hypothesis that the expression of alpha-fetoprotein is regulated by glucocorticoid receptor complex in proliferating hepatocellular carcinoma cells lead to the conclusion that steroid hormones and/or their antagonists may interfere with the function of glucocorticoid receptors in tumors, consequently regulate tumor growth. The potential of hormonal therapy for treatment of hepatocellular carcinoma is worthy of further investigation.

[Post-operative evaluation of 1000 consecutive hemorrhoid cases]

From September 1983 to October 1988, one thousand consecutive hemorrhoid patients were hospitalized and treated at T.C.V.G.H.A retrospective evaluation based on their admission charts was conducted. Two surgical procedures, wedge hemorrhoidectomy and anoplasty, were compared. We collected and analyzed the following data: sex, age, surgical procedure, post-operative pain, complications and number of days of hospitalization. This study discovered that the larger the major operative area and the greater the number of suture knots, the severer the post-operative pain. For instance, anoplasties resulted in a higher incidence of urine retention (78.1%) and stool impaction (79.4%) than hemorrhoidectomies did. Early complications were found primarily in cases receiving anoplasty, but in later complications, there were no significant differences found between procedures. Anoplasty also resulted in a longer hospital stay, so when dealing with the same degree of hemorrhoid, the simpler the operation, the better the result, because the patients' discomfort can be reduced and hospitalization can be shortened.

Baclofen-induced frontal lobe syndrome: case report

An 81-year-old man with cervical spondylotic myelopathy developed an acute frontal lobe like syndrome with prominent preservation and an abnormal electroencephalogram after being given seven doses (70 mg) of baclofen for spasticity. The clinical symptoms cleared up in 72 hours after the medication was discontinued.

HTLV-1-associated myelopathy: first case reported in Taiwan

Taiwan is geographically, culturally, and socially close to southern Japan, which is an endemic area of human T-lymphotropic virus type 1-associated myelopathy (HAM). Taiwan, however, is not an endemic area of HAM. We report the first case of HAM in a native Taiwanese, a 61-year-old woman, without known HTLV-1 risk factors.

Limunectin. A phosphocholine-binding protein from Limulus amebocytes with adhesion-promoting properties

A protein that binds to and precipitates with pneumococcal C-polysaccharide and a phosphocholine (PC) derivative of bovine serum albumin has been affinity purified from Limulus amebocytes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis reveals that the isolated protein consists of a single polypeptide chain of approximately 50 kDa. It is an intracellular protein localized in the secretory granules of amebocytes according to immunogold staining. Although it shares the PC-binding property with C-reactive protein isolated from Limulus and other animal species, it differs from C-reactive protein in that the latter binds to PC only in the presence of Ca2+, whereas the newly isolated protein binds to PC in a Ca(2+)-independent manner. In this respect, the newly isolated PC-binding protein resembles the antibodies to PC of mouse myelomas. The gene coding for this protein has been isolated. The gene sequence predicts a protein of 54 kDa with an unusual structural feature: it consists almost entirely of 10 contiguous segments, 45 amino acids in length, with extensive homology. Some limited sequence homologies were found between the 54-kDa protein and segments of vitronectin, gelatinase, and collagenase. It binds to bacterial cells, fixed amebocytes, and a number of extracellular matrix molecules. Due to its structural and some functional similarities to other adhesion molecules, the Limulus 54-kDa protein was named "Limunectin."

Effect of aging on phosphate metabolites of rat brain as revealed by the in vivo and in vitro 31P NMR measurements

Changes of phosphate metabolism in brains of neonate, weaning and adult rats were compared using both in vivo and in vitro nuclear magnetic resonance spectra. Ratios of phosphocreatine/nucleoside triphosphate (PCr/NTP) were the same in neonatal brain in both in vivo and in vitro studies, but not in weaning and adult brains. This discrepancy may have resulted from extended cerebral hypoxia due to slowed freezing of the brain by the increased skull thickness and brain mass in the weaning and adult rats. Variations in in vitro extraction condition for this age-related study may lead to systematic errors in the adult rats. Nevertheless, the phosphomonoester/nucleoside triphosphate (PME/NTP) ratios in extracts of brain from neonatal rats were higher than those obtained in vivo. In addition, the glycerophosphorylethanolamine plus glycerophosphorylcholine/nucleoside triphosphate (GPE+GPC/NTP) ratios, which were not measurable in vivo, showed age-dependent increase in extracts of rat brain. Some of the phosphomonoester and phosphodiester molecules in rat brain may be undetectable in in vivo NMR analysis because of their interaction with cellular components. The total in vitro GPE and GPC concentration in brain from neonatal rat was estimated to be 0.34 mmole/g wet tissue.

Spermidine biosynthesis in Saccharomyces cerevisiae. Biosynthesis and processing of a proenzyme form of S-adenosylmethionine decarboxylase

We have cloned and sequenced the Saccharomyces cerevisiae gene for S-adenosylmethionine decarboxylase. This enzyme contains covalently bound pyruvate which is essential for enzymatic activity. We have shown that this enzyme is synthesized as a Mr 46,000 proenzyme which is then cleaved post-translationally to form two polypeptide chains: a beta subunit (Mr 10,000) from the amino-terminal portion and an alpha subunit (Mr 36,000) from the carboxyl-terminal portion. The protein was overexpressed in Escherichia coli and purified to homogeneity. The purified enzyme contains both the alpha and beta subunits. About half of the alpha subunits have pyruvate blocking the amino-terminal end; the remaining alpha subunits have alanine in this position. From a comparison of the amino acid sequence deduced from the nucleotide sequence with the amino acid sequence of the amino-terminal portion of each subunit (determined by Edman degradation), we have identified the cleavage site of the proenzyme as the peptide bond between glutamic acid 87 and serine 88. The pyruvate moiety, which is essential for activity, is generated from serine 88 during the cleavage. The amino acid sequence of the yeast enzyme has essentially no homology with S-adenosylmethionine decarboxylase of E. coli (Tabor, C. W., and Tabor, H. (1987) J. Biol. Chem. 262, 16037-16040) and only a moderate degree of homology with the human and rat enzymes (Pajunen, A., Crozat, A., Jänne, O. A., Ihalainen, R., Laitinen, P. H., Stanley, B., Madhubala, R., and Pegg, A. E. (1988) J. Biol. Chem. 263, 17040-17049); all of these enzymes are pyruvoyl-containing proteins. Despite this limited overall homology the cleavage site of the yeast proenzyme is identical to the cleavage sites in the human and rat proenzymes, and seven of the eight amino acids adjacent to the cleavage site are identical in the three eukaryote enzymes.

[An approach to the mode of case findings of pulmonary tuberculosis in countryside]

Through basic health care network, the mode of symptomatic case finding was adopted to discover, treat and supervise pulmonary tuberculosis patients in countryside. The results showed that its outstanding advantages were high detection rate (13.2%), high proportion of initial treated cases (98.2%), high curative effect and low expenses. The detection rate of smear-positive patients (48.5%) was much higher than that of other case finding modes (P less than 0.05). Sputum conversion was seen in all smear positive cases. They were cured after regular treatment.

Prediction of fatty liver from serum triglyceride levels and body weight indexes

Fatty liver is a common disease in Taiwan. In this study, we tried to evaluate the validity of predicting the presence of fatty liver from clinical data instead of liver biopsy or sonography. From a community survey in Putai, a total of 873 adults older than 30 years and quantified as to triglyceride level, body height, body weight, and the results of the oral glucose tolerance test and upper abdominal sonography were recruited for analysis. Using a receiver operating characteristic (ROC) curve, the best 'cutoff values' for determination of fatty liver were predicted from body weight index and serum triglyceride level in 8 clusters grouped by sex, age and presence or absence of diabetes mellitus. The best cutoff values of triglyceride in the 8 clusters varied from 100 to 170 mg/dl with worse validity. Most of the values were 130 and 140 mg/dl. The cutoff values of body weight index were constant in all clusters and showed greater validity than those for triglyceride. They were 115% or 120%. Their accuracy for the prediction of fatty liver was positively correlated with its prevalence. However, their accuracy was lower than 70% in non-diabetic females. We conclude that body weight index is a good parameter for prediction of fatty liver especially in the high risk groups and we recommend that health-determining cutoff values of serum triglyceride and body weight index should be set at 130 mg/dl and 115%, respectively.

cis-acting elements responsible for interleukin-6 inducible C-reactive protein gene expression

To study the mechanism of induction of human C-reactive protein (CRP) gene expression, we have utilized an in vitro liver cell system to analyze the cis-acting DNA sequences located within the 5'-flanking region of human CRP gene. Stable transfection of human hepatoma cells, PLC/PRF/5, by a CRP gene construct containing the 1 kilobase pair of upstream sequence of the CRP gene demonstrated that this region contained the inducible element(s) which regulated human CRP gene transcription. Dissection of this region by 5', 3' and internal deletion constructs of upstream region of the CRP gene fused to a reporter gene, chloramphenicol acetyl transferase, indicated the presence of two inducible elements located proximal to the site of initiation of transcription, two constitutive enhancer-like elements located distal to the promoter, and a negative regulatory region located between the two inducible elements. We had previously shown that a protein factor from monocytes or HTLV1-infected T-cells, was responsible for CRP induction in hepatoma cells. We have found this factor to be synonymous with interleukin-6. By stable and transient transfection assays in hepatoma cells, recombinant interleukin-6 alone was sufficient to activate both inducible elements.

Paraquat-resistant cell lines derived from Chinese hamster ovary cells

Two paraquat-resistant clones, PR-1 and PR-2, were selected from CHO K1 cells pretreated with ethyl methanesulfonate. PR-1 and PR-2, routinely cultured in a normal medium without paraquat, were six fold more resistant to paraquat than the parental CHO K1 cells. There was no difference in the uptake of [3H]paraquat among PR-1, PR-2, and CHO K1 cells. Both PR-1 and PR-2 cells showed no cross resistance to free radical generating agents and no increase in total activity of superoxide dismutase. The activities of paraquat-dependent NADPH oxidase and glucose-6-phosphate dehydrogenase were significantly reduced in PR-1 and PR-2 cells, hence the rate of paraquat radical formation will be limited. In addition, an elevation of glutathione levels in PR-1 cells or an increase in glutathione S-transferase activity in PR-2 cells may also play a certain role in protective mechanisms against the toxicity of paraquat.

Specific high-affinity binding of host cell proteins to the 3' region of rubella virus RNA

Replication of rubella virus is initiated at the 3' end of the genomic RNA. An inverted repeat sequence of 12 nucleotides that is capable of forming a stem-loop structure is located at the 3' end of the RNA, 59 nucleotides upstream from the poly (A) tail. We screened the 158-bp region of the 3' end of the virus, including the stem-loop structure, for its ability to bind to host-cell proteins. Specific high-affinity binding of three cytosolic proteins with relative molecular masses (Mr) of 61, 63 and 68 kD to the stem-loop structure was observed by UV-induced covalent crosslinking. Altering the stem structure by removal of specific bases abolished the binding interactions. The binding of the host proteins is greatly increased after infection and coincides with the appearance of negative strand RNA synthesis. The increase in binding is dependent on new protein synthesis. The amount of the 61-kD protein that binds varies in uninfected cells and is maximal in cells that are in the stationary phase of growth. All binding activity could be abrogated by alkaline phosphatase treatment of cell lysates. A possible role of these host proteins in the replication of rubella virus is discussed.

Hydrolysis of proteins and peptides in a hermetically sealed microcapillary tube: high recovery of labile amino acids

A method for the hydrolysis of peptides and proteins in a hermetically sealed microcapillary tube has been developed. The method is based on the concept that oxidative degradation of labile amino acids during acid hydrolysis of proteins and peptides at high temperature can be reduced to a minimum by limiting the ratio of air to liquid (v/v, less than 1:10) in a microcapillary tube. Furthermore, the physical constraints imposed by the capillary tube will restrict the exposure of the protein solution to air at a very limited area at the meniscus of the liquid. This method eliminates the necessity of time-consuming sealing under vacuum and/or flushing with nitrogen to remove oxygen in the hydrolysis tube. High recovery of labile amino acids can be obtained in a reproducible manner. Because of the simplicity and high reproducibility of the method described, it could be the method of choice for the hydrolysis of protein and peptide intended for quantitative amino acid analysis. Performic acid oxidation is performed at 50 degrees C for 10 min instead of 4 to 20 h at 0 degrees C to achieve an equally good yield of cysteic acid and methionine sulfone from peptides and proteins.

Nucleotide sequence of the 24S subgenomic messenger RNA of a vaccine strain (HPV77) of rubella virus: comparison with a wild-type strain (M33)

A full-length cDNA clone for the 24S subgenomic mRNA of the vaccine strain (HPV77) of rubella virus has been isolated from a cDNA library made from the RNAs of infected cells. Starting from the first Met start codon, the 24S mRNA codes for a precursor protein of 1063 amino acids (aa). This precursor encodes a capsid protein of 300 aa, and two envelope proteins, E1 (481 aa) and E2 (282 aa). Both the E1 and E2 proteins are preceded by a stretch of 21 hydrophobic aa, characteristic of a signal peptide, and each has three putative glycosylation sites in the polypeptide chains. Comparison between the structural proteins of the vaccine and the wild-type (wt; M33) strains of rubella virus, revealed that the E2 protein of the vaccine strain differs, in its apparent Mr, by approx. 3 kDa, from the wt strain. The difference could be due to decreased glycosylation of the vaccine strain E2 protein, as revealed by [3H]mannose incorporation studies. Five single-aa changes in the structural proteins occurred during the attenuation process, one each in the capsid and the E1 protein and three in the E2 protein. The change of Thr-412----Ile in the E2 protein results in the loss of a putative glycosylation site at Asn-410, which offers a plausible explanation for decreased glycosylation of the E2 protein from the vaccine strain of rubella virus.

Steroid hormone receptors in meningiomas of Chinese patients

Meningioma is a hormone-related intracranial tumor. Brain tumor samples were collected from 32 Chinese patients, 20 of whom had meningiomas. Estrogen receptors were present in 6 of 17 meningiomas, 1 hemangioblastoma, 1 gemistocytic astrocytoma, and 1 neurilemoma. Of the 26 samples assayed for progesterone receptors, measurable bindings were found in 14 of 17 meningiomas, 1 of 2 astrocytomas, 1 malignant lymphoma, 1 hemangioblastoma, 1 ganglioglioma, 1 glioblastoma multiforme, 1 anaplastic ependymoma, 1 small cell sarcoma, and 1 neurilemoma. Androgen receptors were found in 8 of 19 meningiomas, but not in the 11 other brain tumors examined. Measurable glucocorticoid receptors were found in 15 of 19 meningiomas, 1 malignant lymphoma, 1 hemangioblastoma, 2 craniopharyngiomas, 1 neurilemoma, 1 of 2 glioblastomas, and 1 of 2 astrocytomas. Of the 10 samples examined for tyrosine aminotransferase activity, measurable enzyme activity was found in 7 of the 8 meningiomas, but not in the single hemangioblastoma nor in the single craniopharyngioma. In accordance with other published studies, the results from this study also suggest that the growth of meningiomas may be regulated by hormones, and that the role steroid hormones and their receptors play in the meningioma is worthy of further investigation.

Analysis of monoamines in the cerebrospinal fluid of Chinese patients with neurological diseases

Levels of dopamine (DA), 3-methoxy-4-hydroxy-phenylacetic acid (HVA), 5-hydroxy-indoleacetic acid (HIAA), 5-hydroxytryptamine (HT), 5-hydroxytryptophan (HTP), and 3, 4-dihydroxyphenylalanine (DOPA) in cerebrospinal fluids (CSF) of twenty-four Chinese with or without neurological diseases were determined simultaneously. The level of HIAA in the CSF of myelopathy-spondylosis patients and the level of DA in CSF of the myelopathy-tumor patients were higher than that of the control. No difference in levels of monoamines and their metabolites was observed between the control and patients with dementia.

Rubella virus: mechanism of attenuation in the vaccine strain (HPV77)

The vaccine type (HPV77 strain) of rubella virus replicates slower and manifests a delayed appearance of cytopathic effect in Vero-76 cells as compared to wild-type virus (M33). The change in cytopathic effect coincides with the delayed appearance of both genomic and subgenomic RNA as well as viral structural proteins in the cell. The delay in the appearance of the viral proteins in the cells was also evident when the cells infected with the vaccine-type virus were treated with the lysosomotropic agent such as chloroquine. Binding studies using [35S]methionine-labeled virus showed that the vaccine-type virus bound to the cells poorly and the binding was not completely competed out with the cold virus.

Identification of the cysteine residue of beta-tubulin alkylated by the antimitotic agent 2,4-dichlorobenzyl thiocyanate, facilitated by separation of the protein subunits of tubulin by hydrophobic column chromatography

The mechanism of action of the antimitotic drug 2,4-dichlorobenzyl thiocyanate (DCBT) has been examined in detail. Shown in previous studies to inhibit tubulin polymerization [Abraham, I., Dion, R. L., Duanmu, C., Gottesman, M. M., & Hamel, E. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 6839-6843] and to form a covalent bond preferentially with beta-tubulin [Bai, R., Duanmu, C., & Hamel, E. (1989) Biochim. Biophys. Acta 994, 12-20], DCBT has now been documented to interact at low concentrations with a high degree of specificity at cysteine residue 239 of beta-tubulin. These low DCBT concentrations also result in the partial inhibition of tubulin polymerization. Such findings strongly indicate that cysteine-239 of beta-tubulin is essential for microtubule assembly. Although alpha-tubulin is alkylated almost as well as beta-tubulin when the drug:tubulin ratio = 5:1 (Bai et al., 1989), beta-tubulin is alkylated about 25 times as extensively as alpha-tubulin, almost exclusively at Cys-239, when the drug:tubulin ratio = 1:5. In addition, we find that low concentrations of DCBT do not affect the binding of colchicine to tubulin but that colchicine and related compounds do reduce the alkylation of tubulin by DCBT. This suggests that Cys-239 of beta-tubulin is not involved in the binding of colchicine to tubulin but that this amino acid residue is at least partially masked by the drug when it is bound to the protein. We also describe a column chromatography procedure (hydrophobic chromatography on decylagarose) useful for the preparative resolution of unalkylated, although denatured, alpha- and beta-tubulin.

Studies on peptides. CLXVII. Solid-phase syntheses and immunological properties of fragment peptides related to human malaria circumsporozoite protein

A glycine-linked tetramer of Asn-Ala-Asn-Pro, a tandem repeated sequence of malaria circumsporozoite (CS) protein, was synthesized by the Boc-based solid phase method, followed by deprotection with 1 M trimethylsilyl trifluoromethanesulfonate-thioanisole in trifluoroacetic acid. In addition, three tetramer-related peptides were similarly synthesized, i.e., a 34-residue peptide [linked with TH, a proposed T-cell epitope of CS, at the C-terminus of the tetramer], a 46-residue peptide and a 59-residue peptide [linked with HA or HA', two proposed T-cell epitopes of influenza hemagglutinin protein, at the N-terminus of the above 34-residue peptide]. Their immunological properties were examined by enzyme-linked immunosorbent assay, for which three different congenic strains of mouse were used to raise the specific antibodies. Despite conjugation of T-cell epitopes to the tetramer, the mice of low-responder strains to the tetramer failed to produce any antibody specific to the tetramer. However, with the aid of recombinant interleukin 2 as an adjuvant, the low-responder mice produced antibody with relatively high titers.

Glucocorticoid receptors in hepatocellular carcinoma and adjacent liver tissue

Glucocorticoid and progesterone receptors, tyrosine aminotransferase, gamma-glutamyltransferase and alpha-fetoprotein levels were determined in human hepatocellular carcinoma (HCC) and adjacent liver tissues. Glucocorticoid receptor was present in seven of ten HCC samples, values ranged from 1.9 to 66.8 fmol/mg protein. Progesterone receptor was present in two of ten HCC samples with values of 1.7 and 7.2 fmol/mg protein, respectively. In the adjacent liver tissues, no measurable progesterone receptor was found and only one sample had glucocorticoid receptor with a value of 3.0 fmol/mg protein. The increase of glucocorticoid receptor in HCC samples was coincident with a decreased level of tyrosine aminotransferase and an increased level of gamma-glutamyltransferase. No correlation was found among glucocorticoid receptor level, serum or tissue alpha-fetoprotein levels. The presence of glucocorticoid receptors in HCC suggest that hormones may play an important role in the formation of hepatoma, and hormonal therapy may be useful for patients with HCC.