Fluctuation of hepatitis C virus quasispecies in persistent infection and interferon treatment revealed by single-strand conformation polymorphism analysis

Hepatitis C virus (HCV) populations in vivo consist of heterogeneous mixtures of genetically different but closely related variants defined as a 'quasispecies'. The longitudinal fluctuation of HCV quasispecies populations in chronic hepatitis C has not been elucidated. Serial plasma samples were obtained from four patients with chronic hepatitis C (two patients without any treatment and two patients treated with interferon), and cDNA fragments containing the 5'-terminal region of the E2 gene of HCV were amplified from plasma RNA using PCR. Since conventional cloning of PCR products detects only a small part of the entire population, PCR products of each sample were separated by electrophoresis using single-strand conformation polymorphism (SSCP) analysis, which can distinguish DNA fragments of the same size as different electrophoretic bands depending on their sequence-specific conformation. Separated DNA fragments were recovered from SSCP bands in gels and their nucleotide sequences determined. SSCP electrophoresis separated PCR products into bands with different mobility. Sequence analysis of these bands confirmed that HCV populations in each patient are composed of quasispecies with different E2-hypervariable regions (HVR), which are known to contain antibody epitopes. Different patterns of variation in the HVR of quasispecies were observed in individual patients with different clinical features over time during chronic infection. Following interferon treatment, some quasispecies disappeared during the treatment and reappeared after the end of the treatment, whereas other quasispecies in the same patient remained during the treatment suggesting that the sensitivity to interferon is different among quasispecies.

Detection and quantification of hepatitis C virus RNA replication in the liver

To investigate the correlation between the replication of hepatitis C virus in liver and the clinical and histopathological features, we detected and quantified plus and minus strands of HCV-RNA in plasma and in livers of patients with chronic hepatitis C by a quantitative polymerase chain reaction. RNA was extracted from the plasma and liver tissue of ten patients with biopsy-proven chronic hepatitis C. The plus and minus strands of HCV-RNA were detected by a strand-specific reverse transcription with either sense or anti-sense oligonucleotide primers deduced from the hepatitis C virus genome, and a standard HCV-RNA with an enzyme restriction site was used to quantify the amount of HCV-RNA. Both plus and minus strands of HCV-RNA were detected from the liver tissue of all patients included. The amount of plus-stranded HCV-RNA in the liver was 10 times higher than that of minus-stranded HCV-RNA. Plus-stranded HCV-RNA was detected in the plasma in all patients, while the minus strand was not detected in any patient. There was a weak correlation between the amount of both strands of HCV-RNA in the liver and that of the plus strand in plasma. There was no significant correlation between the amount of liver HCV-RNA and serum alanine transaminase and aspartate transaminase levels, or histopathological findings in the liver. The present method of detecting and quantifying liver HCV-RNA is simple and sensitive; it may be used to detect residual hepatitis C virus replication after the disappearance of plasma HCV-RNA in acute hepatitis or in chronic hepatitis after interferon treatment.

Endothelin-1 acts as an autocrine growth factor for normal human keratinocytes

Endothelin-1 (ET-1) is an endothelium-derived 21 amino acid vasoconstrictor peptide possessing two intrachain disulfide bridges. Recently it has become evident that isoforms of ET (ET-1, -2, and -3) have a wide range of pharmacological effects in various tissues and act as autocrine/paracrine factors. We demonstrate here that ET-1 is secreted from normal human keratinocytes and may work as an autocrine growth factor through a specific receptor. In this study, human foreskin keratinocytes were cultured in serum-free MCDB 153 medium. Cell growth and [3H] thymidine incorporation in low and high Ca++ concentration media was stimulated by ET-1, -2, and -3 with similar potencies. The strongest response was observed at 10 nM ETs, whereas stimulatory activity was reduced at 100 nM. ETs suppressed keratinocyte differentiation as measured by reactivity with involucrin antibody. Plasminogen activator activity (mainly urokinase) in the medium was also stimulated by the addition of 10 nM ETs. ET-1-like immunoreactivity measured by radioimmunoassay was 1.4 fmol/day/10(6) cells in non-treated condition medium. Among the various cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-1 alpha, and transforming growth factor-beta stimulated ET-1 secretion in a dose-dependent manner. The strongest response (ten-fold) was observed upon the addition of 10 ng/ml TNF-alpha. Scatchard plot analysis of [125I] ET-1 binding to keratinocytes revealed the presence of a single class of high affinity receptors (KD 50 pM, 9 x 10(3) sites/cell). Binding was competitively inhibited by the addition of unlabeled ET-1 and -2 with similar affinities and by ET-3 with weaker affinity. ET-1 mRNA expression in keratinocytes was detected by reverse transcription-polymerase chain reaction and was increased by treatment with 10 ng/ml TNF-alpha. These results suggest that ET-1 acts as an autocrine growth factor for keratinocytes through a specific receptor.

Phenotypic change in portal fibroblasts in biliary fibrosis

Portal fibroblasts have been considered responsible for biliary fibrosis. Since lipocytes show differentiation toward myofibroblast-like cells in hepatic fibrogenesis, we studied whether similar differentiation of portal fibroblasts could be observed in biliary fibrosis. We examined rat livers after bile duct ligation by double immunofluorescent staining of alpha-smooth-muscle actin (alpha-smA) and desmin and also by electronmicroscopy. In the portal tract of normal livers, alpha-smA-positive cells were noted only in the vessel wall, whereas desmin-positive cells were occasionally seen in the connective tissue as well. With the development of biliary fibrosis, alpha-smA was remarkably expressed in the portal connective tissue, while desmin was seen in a small portion of alpha-smA-positive cells around proliferating bile ducts. In normal livers, portal fibroblasts presented quiescent features, such as a small Golgi complex and a few cisternal profiles of endoplasmic reticulum under electron microscopy. After 7 days of bile duct ligation, portal fibroblasts proliferated, were arrayed in multilayers, and were associated with collagen bundles. Some of these fibroblasts had numerous cytoskeletal components, and developed rough endoplasmic reticulum and a dense body. These data suggest that portal fibroblasts appear to differentiate toward myofibroblasts in biliary fibrosis.

Isolation and characterization of a diagnostic polysaccharide antigen from larval Echinococcus multilocularis

A diagnostic antigen, C-antigen, was evaluated in serodiagnosis of alveolar hydatid disease by Western blotting. The C-antigen migrated diffusely to the region of 30-35 kDa in 8% polyacrylamide-SDS gel electrophoresis. We isolated this antigen from a crude metacestode extract by a simple method of phenol/chloroform extraction. The isolated antigen was resistant to boiling, proteolysis and acid hydrolysis, but destroyed with sodium periodate. Such lectins as peanut agglutinin (PNA), Ricinus communis lectin (RCA120) and wheatgerm agglutinin (WGA) were capable of binding with the isolated antigen; no binding to concanavalin A (Con A), Lens culinaris agglutinin (LCA) or Phaseolus vulgaris (PHA-E4) was demonstrated. C-antigen is associated with a polysaccharide containing galactose and N-acetyl glucosamine residues.

Hepatitis C virus after interferon treatment has the variation in the hypervariable region of envelope 2 gene

There is a hypervariable region in the envelope 2 gene of the hepatitis C virus genome, whose heterogeneity in different hepatitis C virus isolates has been suggested to be a result of the immune selection of escape variants. To determine the role of hypervariable region variants in the mechanism of resistance to interferon observed in 75-80% of interferon-treated patients with chronic hepatitis C, hypervariable region sequences were compared before and after interferon treatment. Eight patients with chronic hepatitis C were treated with recombinant interferon-alpha-2b. DNA containing the hypervariable region was obtained by reverse transcription-polymerase chain reaction from serial plasma samples of each patient and directly sequenced without cloning to determine changes in the predominant sequence. In two patients, hepatitis C virus-RNA was eliminated by interferon treatment. In the remaining six patients, hepatitis C virus-RNA was not eradicated. The predominant hepatitis C virus which survived interferon treatment was the mutant hepatitis C virus with 3-19 out of 81 nucleotide substitutions in the hypervariable region, resulting in 2-14 out of 27 amino acid changes. Most of the nucleotide substitutions were nonsynonymous, indicating that there were positive selections for amino acid changes in the hypervariable region. The change rate was significantly higher in patients whose plasma hepatitis C virus-RNA was consistently detectable during and after interferon treatment than in patients whose plasma hepatitis C virus-RNA became undetectable during treatment and reappeared after the cessation of the treatment (4.23 +/- 0.43 vs 0.77 +/- 0.20 x 10(-1)/site/year, p < 0.01). This suggests that the evolution of the hypervariable region was associated with the effect of interferon treatment. These results suggest that hypervariable region variants play an important role in maintaining persistent infection during interferon treatment by evading host immune surveillance.

A prospective study on hepatocellular carcinoma in liver cirrhosis: respective roles of alcohol and hepatitis C virus infection

To assess the interaction of alcohol and HCV infection in hepatocarcinogenesis, we prospectively studied 447 patients with liver cirrhosis (LC) who presented to our out-patient clinics in a month; 163 patients with habitual drinking (AL-LC) who had taken more than 72 g alcohol per day (HCV positive 79 cases: HCV+AL; HCV negative 84 cases: AL); 176 with HCV infection but without alcohol intake; 39 with HB infection; and 82 with liver disease from other etiologies such as primary biliary cirrhosis (PBC). In the HCV group, HCC developed in 15 patients in the first year and 10 in the second year; the cumulative appearance rate was 11% and 16%, respectively. There was no difference in the HCC appearance rate between the two groups. In the AL group, the cumulative HCC occurrence rate was only 2% in the first year, and 2% in the second year. The appearance rate was significantly lower in the AL group compared with the HCV and the HCV+AL groups. One-hundred and fourteen patients (94 with HCV, 20 with HCV+AL) who had a history of blood transfusion more than 10 years ago were selected. A year-adjusted disease occurrence rate calculated by the Kaplan-Meier method showed that the HCV+AL group had a significantly higher disease occurrence rate than the HCV group. Theses results suggest that although alcohol alone does not become an independent risk factor for HCC from LC, it may accelerate the development of HCC caused by HCV, at least in the group with a history of blood transfusion.

Sequential change of the hypervariable region of the hepatitis C virus genome in acute infection

Hepatitis C virus (HCV) infection is characterized by persistence of liver inflammation that often leads to end-stage liver disease, although the mechanisms are not fully understood. A hypervariable region (HVR) has been reported in the E2/NS1 region of the HCV genome, in which striking diversity is found among different HCV isolates. To investigate the association of the HVR alterations with the clinical courses of HCV infection, a longitudinal analysis of the HVR in patients with acute HCV infection was carried out. Plasma samples were obtained at several times in three patients with acute hepatitis C. Plasma RNA was extracted and reverse transcribed, and DNA fragments that included the HVR were amplified by PCR. The sequences of the HVR were directly determined from the PCR products by the dideoxy chain termination method, from which amino acid sequences were deduced. In all cases, plasma HCV-RNA disappeared with the improvement of the initial alanine aminotransferase (ALT) elevation, but HCV-RNA reappeared about 1 year later with or without deterioration of the hepatitis. In a case of sporadic acute hepatitis, the HCV in the recurrent phase had seven amino acid substitutions in the HVR compared with that in the acute phase, although no amino acid changes were noted during the initial acute phase. In a case of posttransfusion hepatitis, a marked difference was observed between the acute and the recurrent phases, with an amino acid homology of 30% (8/27). The mutation rate of the HVR had a tendency to accelerate as the HCV infection progressed to the chronic stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Rapid sequence variation of the hypervariable region of hepatitis C virus during the course of chronic infection

To evaluate the clinical significance of sequence variations in the hypervariable region of hepatitis C virus during the course of chronic infection, we performed pairwise comparison of the predominant nucleotide sequences. Hepatitis C virus RNA was extracted from two plasma samples obtained from 12 chronically infected Japanese patients over approximately 1 yr. Complementary DNA containing the hypervariable region was amplified by means of reverse transcription-polymerase chain reaction and was directly sequenced for determination of predominant sequences. In all 12 individuals, the predominant sequence of the hypervariable region at the second time point differed from that at the first time point, and significant sequence variation was observed during this short period. A high proportion of these nucleotide substitutions (90%) resulted in changes of predicted amino acid sequences, indirect evidence of in vivo positive selection for these variants. There appeared to be an important difference in the rate of nucleotide sequence variation of the hypervariable region between four patients with flare-ups of their ALT levels (1.54 to 2.24 x 10(-1)/genome site/yr) and eight patients with quiescent courses (0.13 to 1.21 x 10(-1)/genome site/yr). These results demonstrate that rapid sequence variations of the hypervariable region of predominant virus population take place during the natural course of chronic hepatitis C virus infection. These sequence variations seem to occur as an adaptive response of hepatitis C virus to evade host immunity and may play a major role in the establishment of persistent infection and in the occasional flare-up of hepatitis.

Structural diversity in the alpha 2-->8-linked polysialic acid chains in salmonid fish egg glycoproteins. Occurrence of poly(Neu5Ac), poly(Neu5Gc), poly(Neu5Ac, Neu5Gc), poly(KDN), and their partially acetylated forms

alpha 2-->8-Linked polysialic acid (polySia) chains terminate O-linked oligosaccharide chains on Salmonidae fish egg polysialoglycoproteins (PSGPs). Expression of these surface PSGPs are developmentally regulated and the polySia epitope is functionally implicated in a number of distinct species-specific cell-cell recognition events during fertilization and early embryogenesis. To better understand the functional diversity of these PSGPs, structural studies of the polySia chains isolated from three genera and eight species of Salmonidae fish eggs were carried out by chemical, immunochemical, enzymatic, and 1H NMR methods. A remarkable degree of structural diversity was found, including differences in the N-acyl groups, i.e. N-acetylneuraminic acid (Neu5Ac) or N-glycolylneuraminic acid (Neu5Gc), and in the presence of either O-acetyl substitution at C4, C7, or C9 or O-lactyl substitution at C9. The presence of heteropolymers containing both Neu5Ac and Neu5Gc residues was also an unexpected finding. Accordingly, the different forms of alpha 2-->8-linked homo- and heteropolymers of these polySia structures include: poly(Neu5Ac), poly(Neu5Gc), poly(Neu5,chi Ac2), poly(Neu5Gc chi Ac), poly(Neu5Ac, Neu5Gc), poly-(Neu5Ac, Neu5,chi Ac2), poly(Neu5Ac, Neu5Gc chi Ac), poly(Neu5Gc,Neu5,chi Ac2), and poly(Neu5Gc, Neu5-Gc chi Ac), where chi represents the site of acetylation at carbon atom 4, 7, or 9. The significance of this new structural information, together with our recent finding of alpha 2-->8-linked polydeaminoneuraminic acid, poly(KDN), in the rainbow trout egg vitelline envelope, is that it demonstrates the natural occurrence of multiple forms of alpha 2-->8-linked polySia chains in Salmonidae fish glycoproteins that have not been previously described. The results also predict that a remarkable array of polysialylated glycoconjugates is yet to be discovered in animals other than teleost fishes.

Role of hepatic vitamin A and lipocyte distribution in experimental hepatic fibrosis

Lipocytes are the major site of hepatic vitamin A storage, and they have been demonstrated to lose their vitamin A content in the process of hepatic fibrosis. To investigate the relationship between hepatic vitamin A content and the degree of hepatic fibrosis, we measured levels of retinyl palmitate and retinol in the CCl4-induced fibrotic liver using high-performance liquid chromatography. We estimated hepatic collagen content using a spectrophotometric analysis with sirius red, and also by measuring hydroxyproline levels. Lipocytes were detected by an immunoperoxidase method with anti-desmin antibody, and were counted morphometrically through a Texture Analyzing System. A significant negative correlation was observed between the level of retinyl palmitate and collagen content (r = -0.64) as well as the hydroxyproline level (r = -0.69) in the CCl4-induced fibrotic liver. In the process of fibrosis, hepatic retinol levels were elevated in association with a decrease in retinyl palmitate. In particular in the early stage of fibrosis, lipocytes increased remarkably in number in fibrotic areas in spite of a decrease in total hepatic vitamin A. The present study suggests that an increase in hepatic retinol as well as a decrease in retinyl palmitate may facilitate the process of hepatic fibrosis produced by lipocytes.

Genetic changes and histopathological grades in human hepatocellular carcinomas

Loss of heterozygosity (LOH) on chromosomes 1p, 4q, 5q, 8p, 13q, 16q, 17p, and 22q, and mutation of the p53 gene were simultaneously analyzed in 63 hepatocellular carcinomas (HCCs) with distinct histopathological grades, 80% of the tumors being from patients who had been exposed to hepatitis B virus (HBV) or hepatitis C virus (HCV). The frequencies of LOH on 8 chromosomes were 0-25% in 10 well differentiated HCCs, LOH being observed on 4q, 5q and 17p, 21-53% in 26 moderately differentiated HCCs, LOH on 8p and 17p being high, and 29-75% in 27 poorly differentiated HCCs, LOH on 17p, 4q and 8p being the most frequent. p53 gene mutation was detected in moderately and poorly differentiated HCCs at 15% and 52%, respectively, but not at all in well differentiated HCCs. Of the mutations detected, 42% were transition mutation and only 5% were CpG transition, in contrast to the high frequencies of these types of mutations in colon tumors (78% and 54%, respectively). LOH on every chromosome and p53 mutation were more frequent in more advanced tumors, and accumulation of genetic changes increased with increase of the histopathological grade. Frequency of genetic changes in HCCs from HBV-positive patients was comparable to that from HCV-positive patients. The present results suggest that accumulation of genetic changes in multiple tumor suppressor genes, especially LOH on 17p, 4q and 8p, and mutation in p53 gene, are involved in the progression of liver cancer, and LOH on 17p and 4q precedes other genetic changes. Differences in the direction of p53 mutation between HCC and colon carcinoma suggest that liver carcinogens are distinct from colon carcinogens. Furthermore, mechanisms affecting the frequency of LOH in HCCs in HBV-infected patients may be similar to those in HCV-infected patients.

Detection of hepatitis C virus RNA in the liver by in situ hybridization

To examine HCV infection histologically, we attempted non-radioactive in situ hybridization of HCV-RNA in the liver. We amplified cDNA probe (360 base pairs) by PCR using the primers deduced from the core region of the HCV genome. The probe was labelled with digoxigenin by PCR and used for in situ hybridization on paraformaldehyde-fixed frozen liver sections. The hybrids were visualized immunohistochemically with alkaline-phosphatase-conjugated anti-digoxigenin and alkaline-phosphatase substrates. HCV-RNA-cDNA hybrids were detected in 21 of 24 patients with positive serum HCV markers, whereas there were no positive signals in the liver of 12 cases without HCV infection. The signal intensity of HCV-RNA-cDNA hybrids was abolished after RNase treatment. Various other specificity experiments also verified specific hybridization of HCV-RNA-cDNA. HCV-RNA was visualized in liver cells and most of them were regarded as hepatocytes from their characteristic features. The infected hepatocytes were frequently associated with mononuclear cell infiltration. Hepatocytes positive for HCV-RNA were sometimes binuclear and distributed in various patterns among cases tested. The present in situ hybridization of HCV RNA is highly sensitive and specific and the results suggest the host immune response to HCV-infected cells.

Alpha-smooth-muscle actin expression in normal and fibrotic human livers

To determine the significance of the expression of alpha-smooth-muscle actin in the fibrotic human liver, normal and diseased livers were stained with anti-alpha-smooth-muscle-actin antibody by an immunoperoxidase method. Vitamin A-containing lipocytes were also identified by the modified Kupffer's gold chloride method. In the normal human liver, lipocytes as well as vascular smooth muscle cells expressed alpha-smooth-muscle actin. In alcoholic liver disease, there was an increase in the cells positive for alpha-smooth-muscle actin adjacent to the fibrotic areas, but the response of lipocytes to the gold chloride reaction diminished. In chronic hepatitis, the cells positive for alpha-smooth-muscle actin increased around the enlarged portal areas, and the response to the gold chloride reaction did not change appreciably. An increase in the cells positive for alpha-smooth-muscle actin was associated with the progression of hepatic fibrosis in the liver of patients with alcoholic liver disease and chronic hepatitis.

Expression of the hepatocyte growth factor receptor in the regenerating rat liver

The c-met oncogene product is a cell-surface receptor, which ligand is believed to be the hepatocyte growth factor. We studied the expression of c-met oncogene in the regenerating rat liver after either partial hepatectomy or CCl4-induced liver injury. Northern blot analysis showed that after partial hepatectomy the transcripts of c-met decreased at 8 h, reached the minimum at 36 h, and returned to the steady level on the seventh day. In contrast with the hepatectomized liver, the transcripts of c-met increased after CCl4 treatment. These observations suggest that c-met transcription may be regulated differently depending on regeneration signals.

Asymptomatic arteriovenous malformation of the pancreas. Demonstration by Doppler ultrasonography and magnetic resonance imaging

We reported a case of asymptomatic pancreatic AVM, incidentally found on routine ultrasonography and diagnosed noninvasively by means of Doppler ultrasonography and MRI. The diagnosis was confirmed by angiography. This is the first report to demonstrate the characteristics of pancreatic AVM by these two imaging techniques. They proved to be useful in identifying the vascular nature of AVM without the use of a contrast material, which is a definite advantage over DSA and CT. The quality of the image obtained was equivalent or superior to that obtained by DSA and contrast-enhanced CT. Doppler ultrasonography and MRI may serve as the primary imaging techniques of choice in suspected cases of AVM.

Keratinocyte growth factor (FGF-7) stimulates migration and plasminogen activator activity of normal human keratinocytes

Keratinocyte growth factor (KGF), a member of the fibroblast growth factor (FGF) family (and alternatively designated FGF-7), is a paracrine growth factor produced by mesenchymal cells and mitogenic specifically for epithelial cells. The potential effect of KGF on wound healing was assessed in vitro by measuring randomized migration and plasminogen activator (PA) activity of keratinocytes in response to the growth factor. Incubation of normal human keratinocytes with KGF in modified MCDB 153 medium significantly stimulated cell migration and PA activity compared with control (p < 0.001 and p < 0.01, respectively). When tested in these assays on an equimolar basis, 1 nM KGF was at least as potent as transforming growth factor alpha and more active than basic FGF. None of these effects were observed when KGF was administered to fibroblasts or endothelial cells. Stimulation of keratinocyte migration by KGF was dose dependent, and a neutralizing monoclonal antibody against KGF reduced KGF-stimulated migration and cell growth. Zymographic analyses of cell extracts and conditioned medium from KGF-treated keratinocytes revealed increased PA activity, which was mainly attributable to an elevated level of urokinase-type PA. These in vitro results suggest that KGF may have an important role in stimulating reepithelialization during the process of wound repair.

Radiosensitization by a new potent nucleoside analog: 1-(1',3',4'-trihydroxy-2'-butoxy)methyl-2-nitroimidazole(RP-343)

PURPOSE

A new hypoxic cell sensitizer has been synthesized; this is a 2-nitroimidazole nucleoside analog having erythritol as a sugar moiety at the N-1 position of the imidazole ring (RP-343). Its possibility as a potent hypoxic cell sensitizer was compared with those of RP-170 and etanidazole.

METHODS AND MATERIALS

Radiosensitization was tested in two murine tumors, EMT6 using in vitro and in vivo-in vitro assays and SCCVII using growth delay and TCD50 assays. Pharmacokinetic study was performed in Balb/c mice bearing EMT6 tumors and in Beagle dogs. LD50 of each sensitizer was obtained with ICR mice.

RESULTS

As might be expected from the almost identical electron affinities of the three sensitizers, they were equally effective against hypoxic EMT6 cells in vitro. While having the lowest partition coefficient (0.035), RP-343 exhibited almost equally effective distribution to tumors and sensitizing radiation activity. An intravenous (i.v.) injection of 100 mg/kg of RP-343, RP-170 and etanidazole showed an almost equal sensitizer enhancement ratio (SER) of about 1.4 to solid EMT6 tumor under in vivo-in vitro assay and a virtually equal SER of 1.33-1.44 to solid SCCVII tumor under both tumor growth delay assay and TCD50 assay. A great advantage of RP-343 over RP-170 and etanidazole is its very much lower toxicity; their LD50 in mice were > 6.0, 4.3 and 4.8 g/kg, respectively, on i.v. injection. The lower toxicity of RP-343 was supported by its lower concentrations in the brain; the RP-343 AUC for brain was 0.43 times that of RP-170. Three indices were selected to compare the three nitroimidazoles. SER at 5% LD50 doses of RP-343, RP-170 and etanidazole was 1.66, 1.59 and 1.56. At the same toxicity levels, RP-343 was found to have better sensitization of solid tumors over both etanidazole and RP-170. The maximum tumor concentration/AUC for brain (Cmax,tumor/AUCbrain) ratios for RP-343 and RP-170 were 9.62 and 3.98.

CONCLUSIONS

This extremely high ratio of RP-343 could explain its lower toxicity than RP-170 or etanidazole. The therapeutic risk index defined as D1.5/LD50 (D1.5 is the sensitizer dose to obtain the SER of 1.5 in vivo) for RP-343, RP-170 and etanidazole were 0.022, 0.033 and 0.036, respectively. Especially, the effectively lower therapeutic risk index for RP-343 presents the possibility of clinical advantage over etanidazole.

Down-regulation of ubiquitin gene expression during differentiation of human leukemia cells

Ubiquitin, which is ligated covalently to target proteins for their acquisition of a variety of functions, is encoded by multiple unique genes in human cells: two distinct poly-ubiquitin genes with tandemly repeated sequences of 3 or 9 moieties and two mono-ubiquitin genes fused with small and large ribosomal proteins. We found that all classes of ubiquitin genes as well as the two genes encoding the ribosomal proteins S17 and L31 were expressed at abnormally high levels in various hematopoietic malignant tumor cells. In contrast, in vitro terminal differentiation of various immature leukemic cell lines, such as HL-60 promyelocytic leukemia cells and K562 erythroleukemia cells into monocytic, granulocytic and erythroid cells, induced by various agents was found to cause rapid and marked down-regulation of ubiquitin expression, irrespective of the cell type, direction of differentiation or type of signal. These findings suggest that the expressions of the multiple ubiquitin genes, coordinated with those of the ribosomal protein genes, are in a dynamic state during growth and differentiation of leukemia cells.

Hepatocellular carcinoma producing universal type of alkaline phosphatase

We report on a 54-year-old man with hepatocellular carcinoma (HCC) associated with a marked elevation of serum alkaline phosphatase (ALP) levels. Serum ALP was biochemically similar to that of universal (liver/bone/kidney) type. The noncarcinomatous area revealed typical micronodular cirrhosis due to excessive alcohol consumption. By histochemical staining, ALP activity was demonstrated diffusely within the cytoplasm of carcinoma cells. Immunohistochemical observation of the carcinoma cells excluded the intestinal or placental type of ALP. Tissue extracts from the carcinomatous area had much higher ALP activities than those from a noncarcinomatous area, which also showed characteristics of the universal type. The present HCC is the first reported to produce and excrete the universal type of ALP.