Persistent induction of apoptosis and suppression of mitosis as the basis for curative therapy with S-1, an oral 5-fluorouracil prodrug in a colorectal tumor model

In an effort to improve the therapeutic selectivity of 5-fluorouracil (FUra) against colorectal cancer, S-1, a combination agent including a prodrug of FUra with two modulators, was recently developed by Taiho Pharmaceuticals Co. S-1 is a combination of tegafur (FT), 5-chloro-2,4-hydroxypyridine, and potassium oxonate in the molar ratio of 1.0:0.4:1.0, with the latter two components as inhibitors of dihydropyrimidine dehydrogenase and phosphoribosylpyrophosphate transferase, respectively. In this study, the therapeutic selectivity and efficacy of S-1 (oral) was compared with FT (oral) and FUra (i.v. infusion) in rats bearing advanced colorectal cancer by using clinically relevant schedules. The maximum tolerated doses (MTDs) of S-1, FT, and FUra were 31.5, 200, and 25 mg/kg/d for 7 days and 22.5, 150, and 12.5 mg/kg/d for 28 days, respectively. The therapeutic index of S-1 was 4- to 5-fold higher than that of either FT or FUra. S-1 achieved 100% complete tumor regression (CR) at its MTD in both 7-day and 28-day schedules. Furthermore, the high incidences of stomatitis, alopecia, and diarrhea observed with FUra and FT, were not observed with S-1. In an attempt to understand the basis for the observed superior therapeutic selectivity with S-1, we studied pharmacokinetic analysis of FUra, drug-induced apoptosis, suppression of mitosis, and inhibition of thymidylate synthase (TS) after S-1, FUra, or FT administration. The peak plasma FUra concentrations derived from FUra or S-1 (FT) at comparable MTDs were similar, but the plasma level of FUra was higher with S-1 than with FUra. Induction of high and sustained apoptosis was achieved with S-1. Although the initial level of apoptosis induced by FUra was comparable to S-1, it was not sustained. The sustained level of apoptosis appears to correlate with tumor growth inhibition. Mitotic figures were more greatly suppressed with S-1 treatment than with FUra. Studies on TS inhibition indicated that, although both S-1 and FUra caused a 4- to 6-fold induction of total TS protein, single oral administration of S-1 was superior to 24-h infusion of FUra in suppressing free TS. The data are consistent with the observation that the therapeutic efficacy of S-1 (100% cure) over FUra is associated with high and sustained levels of drug-induced apoptosis, greater suppression of mitosis, and inhibition of free TS in tumor tissues.

Long-term outcomes in pediatric liver recipients: comparison between cyclosporin A and tacrolimus

In recent years, tacrolimus (FK506, TAC) has been increasingly utilized in liver transplantation. However, long-term risks and benefits as compared with conventional cyclosporin A (CsA) have not been fully elucidated. This retrospective study examined the potential outcome differences between TAC- and CsA-based immunosuppressive therapy in pediatric liver transplant recipients. From March 1988 to December 1996, 218 children (aged 0.1-17 yr) underwent 238 orthotopic liver transplantations; 58.7% (128/218) were under 2 yr of age at time of transplant. Initially, the maintenance immunosuppressive regimen consisted of CsA and prednisone, with antilymphocytic preparations (MALG, ATGAM, and OKT3) as induction therapy. Subsequently, TAC was used first as rescue therapy for steroid refractory rejection in CsA patients and then as maintenance immunosuppression. Fifty-seven out of the 147 CsA patients were converted to TAC for various reasons while 71 patients were placed on TAC as primary maintenance immunosuppression. 62.6 per cent (92/147) of liver recipients on CsA experienced at least one biopsy-proven acute rejection episode as compared to 50.7% (36/71) for TAC patients (p = 0.09); likewise, 34% (50/147) of CsA patients had more than one episode of rejection vs. 18.3% (13/71) for patients on TAC (p < 0.02). Rejection was the reason for conversion from CsA to TAC in 29 of 57 patients. Conversely, 19.0% (28/147) of CsA patients had to be switched to TAC for reasons not related to rejection (i.e. side-effects). The overall incidence of histologically proven chronic rejection was 7.8% (17/218). 10.9 per cent (16/147) of the children who were on CsA initially developed chronic rejection, which was significantly higher compared with one of 71 TAC recipients (p < 0.02). Of these 16 CsA patients with chronic rejection, 50.0% (8/16) underwent retransplantation for graft failure (mean interval from time of diagnosis of chronic rejection to re-transplant, 4.0 months; range 1-8 months), whereas the TAC patient has remained clinically stable with normal liver function tests after 23 months of follow-up. One year after liver transplantation, 72.8% (107/147) of CsA patients were still on steroids (mean dosage 0.20 mg/kg/d), as compared to 42.3% (30/71) of the TAC patients (mean dosage 0.14 mg/kg/d). The incidence of post-transplant lymphoproliferative disorder (PTLD) in Epstein-Barr virus (EBV)-infected patients was 2.2% (2/90), 7.0% (5/71) and 12.3% (7/57) for CsA, primary and TAC-converted groups, respectively. The overall incidence of PTLD was 6.9% (15/218). In summary, pediatric liver transplant recipients treated with TAC as primary maintenance immunosuppressive medication experienced significantly fewer episodes of rejection; especially chronic rejection, which lead to graft loss. However, the trade-off is a potential increased incidence of EBV-related PTLD in these patients.

Posttransplant lymphoproliferative disorders and gastrointestinal manifestations of Epstein-Barr virus infection in children following liver transplantation

BACKGROUND

Epstein-Barr virus (EBV) infection is common after liver transplantation in children and is associated with the risk of posttransplant lymphoproliferative disorders (PTLD).

METHODS

This retrospective study examined the frequency of gastrointestinal (GI) symptoms and the risk of PTLD in pediatric liver recipients who developed symptomatic EBV infection. We reviewed 172 children who received orthotopic liver transplants between March 1988 to December 1994. Twenty-two cases were retransplants. The mean age at transplantation was 3.7 years (range, 0.1-17 years). The immunosuppressive regimens consisted of induction therapy with Minnesota antilymphocyte globulin/antithymocyte globulin/OKT3 in most cases and maintenance therapy with prednisone and either cyclosporine or tacrolimus (FK506).

RESULTS

After 1 year of minimum follow-up, 54 of 172 patients had symptomatic EBV infections (confirmed by serology, histology, or whole blood polymerase chain reaction. At the time of infection, 38.5% (21/54) had either diarrhea or GI bleeding or both. PTLD developed in 11 patients (6.4%). The incidence of PTLD was 42.9% (9/21) when GI bleeding or diarrhea was associated with EBV infections, compared with 6.1% (2/33) when EBV infection was not associated with GI symptoms. Seven of 10 (70%) patients with GI bleeding and 2 of 11 (18.2%) with diarrhea developed PTLD. Of seven patients examined by endoscopy for GI bleeding, two had biopsy-proven PTLD of the GI tract, whereas one of two patients examined by endoscopy for diarrhea had biopsy-proven PTLD.

DISCUSSION

In summary, a high incidence of PTLD was found in patients who developed GI bleeding or diarrhea associated with EBV infection after pediatric liver transplantation. In these patients, endoscopy and biopsy may lead to early diagnosis of PTLD.

Modulation of platinum-induced toxicities and therapeutic index: mechanistic insights and first- and second-generation protecting agents

Platinum-type drugs have proven to be valuable in the treatment of a variety of solid tumors, beginning with the commercial approval of cisplatin 18 years ago. There are several clinically important toxicities commonly associated with the administration of these drugs. Despite the extensive use of cisplatin and carboplatin, the fundamental chemical transformations and mechanisms that underlie their antitumor and toxic effects have not been fully characterized. Several first-generation protective thiols have been clinically studied in an attempt to reduce the toxicity of platinum-type drugs; while some of these agents appear to protect against certain toxicities, nearly all platinum-protecting drugs have their own intrinsic toxicities, which can be additive to the toxicity of platinum-type drugs. Tumor protection by platinum-protecting drugs is an additional untoward effect that is associated with certain types of agents and must be addressed with care. Recent advances in theoretical and laboratory methods and the use of supercomputers have extended our understanding of the possible major mechanisms underlying platinum drug antitumor activity and toxicity; we present strong evidence that there are two classes of chemical species of platinum drug. One class appears to predominantly account for the antitumor activity, and the other class of chemical species produces many of the toxic effects of platinum drugs. We have discovered a new nontoxic, second-generation platinum-protecting agent, known as BNP7787, which appears to selectively inactivate and eliminate toxic platinum species. BNP7787 has recently entered phase I clinical testing in cancer patients.

DNA immunization of infants: potential and limitations

DNA immunization is a relatively new and efficacious approach to vaccination. Only recently have we begun to test the efficacy of DNA vaccines in infants. DNA vaccines for a retrovirus, hepatitis B, influenza, rabies, measles, tetanus toxoid, and sendai virus, have now been proven to induce cellular and humoral immune responses in infant animals. Here we review the field of DNA immunization of newborn animals, some new promising immunization strategies, and the rapid progress obtained in this field.

Rational design of irinotecan administration based on preclinical models

Most clinical drug regimens for irinotecan (CPT-11 [Camptosar]) have been empirically based on classic in vivo pharmacokinetic and pharmacodynamic considerations. We propose an alternative approach that attempts to provide a rationally designed schedule of irinotecan administration based on preclinical data. HL60 cells grown in suspension or as subcutaneously implanted solid xenografts in nude mice served as in vitro and in vivo models to rest the activity of irinotecan or its active metabolite, SN-38. For SN-38, within an effective drug concentration range, scheduling drug administration based on duration of DNA synthesis inhibition significantly potentiated cell kill in vitro, and increasing drug concentrations at suboptimal scheduling did not result in additive cell kill. These data suggested that even though high drug doses may be attainable in vivo, they may not be required to achieve maximum antitumor activity. To test this hypothesis, a sensitive in vivo model to test the toxicity and antitumor activity of CPT-11 is required, which is provided in the human myeloid HL60 xenograft model grown in nude mice. In this model, CPT-11 at a dose 50 mg/kg, daily x5 (MTD) achieved 100% complete tumor regression. This model should be useful to test the hypothesis that for irinotecan, administration of a minimum effective dose (MED) at an optimal schedule can achieve maximum antitumor activity and should therefore prevail over the classic approach of administering the MTD.

Interleukin 15 offers selective protection from irinotecan-induced intestinal toxicity in a preclinical animal model

Irinotecan (CPT-11) is a chemotherapeutic agent that is active in the treatment of a variety of solid tumor malignancies. Diarrhea represents the most common dose-limiting toxicity that is independent of the schedule of administration. A rat model with dose-limiting toxicity profiles that are similar to those observed in patients treated with CPT-11 was developed and used to evaluate the role of interleukin 15 (IL-15) in the modulation of the therapeutic selectivity of CPT-11 in normal rats and rats bearing advanced colorectal cancer. The maximum tolerated dose and lethal dose (LD) of CPT-11 by i.v. push daily x 3 were 150 and 200 mg/kg/day, respectively. CPT-11 at the LD induced a 93-100% incidence of severe diarrhea and an 86-100% incidence of lethality in treated animals. IL-15, a cytokine with multiple mechanisms of action, was used at a 100 or 400 microg/kg/dose with different schedules of administration (3, 8, and 11 doses, i.p.) to protect against CPT-11-induced toxicity. IL-15 offered complete and sustained selective protection against CPT-11-induced delayed diarrhea and lethality. IL-15 also moderately potentiated the antitumor activity of CPT-11 in rats bearing advanced colorectal cancer. Morphological examination of rat intestinal tissues after treatment with LD of CPT-11 revealed dramatic protection of duodenal and colonic tissue architecture by IL-15. CPT-11 alone produced serious damage to duodenal villi and colonic crypts. The results clearly demonstrated the ability of IL-15 to provide significant protection from CPT-11-induced intestinal toxicity with maintenance of antitumor activity, resulting in an increase in the therapeutic index of CPT-11. The clinical relevance of the results obtained in this model system needs to be confirmed.

[Isolation of a lipase-producing Pseudomonas strain and optimization of its fermentation conditions]

A lipase-producing bacterium strain was isolated from soil and was identified as Pseudomonas sp.. Its lipase yield was improved 2.25-fold by combined treatment of UV irradiation and NTG. The lipase fermentation condition for the mutant strain was optimized with Plackett-Burman design and Response Surface Analysis (RSA), and the formula of the optimum medium suitable for industrial scale fermentation was thereby established. A maximum yield of 87.5 U/ml was obtained.

[The determination of diuron and chlortoluron residues in beef and beef products by high performance liquid chromatography]

Amethod for the determination of diuron and chlortoluron in beef and beef products with high performance liquid chromatography is described. The sample was extracted with a mixture of acetonitrile and methanol (50:50, V/V). After filtration, the filtrate was defatted with petroleum ether, then water was added and further extracted with chloroform. The chloroform collected was evaporated in a rotary evaporator(45 degrees C). The residue was dissolved in acetonitrile-methanol(50:50, V/V) mixture, poured into an Al2O3 column and eluted with the same mixture. The eluate was collected for HPLC analysis. The analytical column was Selectosil C18 (5 microns, 250 mm x 4.6 mm i.d.), mobile phase was methanol-water(60:40, V/V) and detection wavelength was UV-245 nm. The minimum amounts of detection were 0.4 ng for diuron and 0.5 ng for chlortoluron. Recoveries were 87.34%-87.64% for diuron and 88.78%-91.94% for chlortoluron.

Caloric intake alters the efficiency of catalase mRNA translation in the liver of old female mice

The free radical theory of aging predicts that calorie restriction, which extends life span, should reduce oxidant damage. In mammals, the oxidative processes centered in the liver are a major source of free radicals. Liver catalase has the dominant role in the intracellular detoxification of hydrogen peroxide. In male rodents, published studies indicate that aging decreases catalase gene transcription and that calorie restriction obviates this effect. In females, published studies are inconsistent, and no molecular mechanisms have been identified. Here we report that, in female mice, aging can lead to an increase in the translational efficiency of hepatic catalase mRNA, and that calorie restriction obviates this effect. Consideration of these results and published studies leads us to propose that the variability in catalase results in females may arise from the small number of studies or from unique aspects of female physiology, perhaps the estrous cycle and its cessation with age.

Health effects of indoor fluoride pollution from coal burning in China

The combustion of high fluoride-content coal as an energy resource for heating, cooking, and food drying is a major exhaust emission source of suspended particulate matter and fluoride. High concentrations of these pollutants have been observed in indoor air of coal-burning families in some rural areas in China. Because airborne fluoride has serious toxicological properties, fluoride pollution in indoor air and the prevalence of fluorosis have been analyzed in a fluorosis area and a healthy nonfluorosis area in China and in a rural area in Japan. For human health, fluoride in indoor air has not only been directly inhaled by residents but also has been absorbed in stored food such as corn, chilies, and potatoes. In the fluorosis area in China, concentrations of urinary fluoride in the residents have been much higher than in the nonfluorosis area in China and in the rural area in Japan. In the fluorosis area, almost all elementary and junior high school students 10-15 years of age had dental fluorosis. Osteosclerosis in the skeletal fluorosis patients was very serious. Urinary deoxypyridinoline in rural residents in China was much higher than in rural residents in Japan. Data suggest that bone resorption was extremely stimulated in the residents in China and that fluoride may stimulate both bone resorption and bone formation. Because indoor fluoride from combustion of coal is easily absorbed in stored food and because food consumption is a main source of fluoride exposure, it is necessary to reduce airborne fluoride and food contamination to prevent serious fluorosis in China.

Interleukin 15 protects against toxicity and potentiates antitumor activity of 5-fluorouracil alone and in combination with leucovorin in rats bearing colorectal cancer

5-Fluorouracil (FUra) modulated by leucovorin (LV) is active in the treatment of colorectal cancer. Diarrhea and stomatitis are the most common dose-limiting toxicities. We have developed a model system in rats bearing a transplantable colon carcinoma sensitive to FUra therapy with dose-limiting toxicity profiles similar to what is observed in patients treated with either daily or weekly schedules of FUra plus LV. Interleukin 15 (IL-15), a cytokine that shares many biological activities with IL-2, was used at different doses (25, 100, and 400 microg/kg) and schedules (three doses before a single dose of FUra, FUra/LV daily x 5, or before each week of FUra/LV weekly x 4, or three doses before a single dose of FUra or FUra/LV daily x 5, then twice daily x 5 for a total of 11 doses) to evaluate its role in the modulation of the therapeutic selectivity of FUra alone and modulated by LV. IL-15 induced a dramatic decrease in chemotherapy-induced gastrointestinal toxicities, significant potentiation of antitumor activity, and an increased therapeutic index of FUra administered on single dose, daily x 5 and weekly x 4 schedules. In contrast, IL-2 (400 microg/kg) significantly potentiated the toxicity of FUra administered as a single i.v. push, with minimal potentiation of the antitumor activity. Taken together, the results clearly demonstrated the ability of IL-15, but not IL-2, to provide significant improvement of the therapeutic index of FUra alone and in combination with LV. The clinical relevance of the results obtained in this model system needs to be confirmed.

New approaches to supporting the failing liver

With the continued, growing disparity between the numbers of organ donations and patients waiting for liver transplantation, various efforts have been made to optimize the allocation of organs, as well as to devise means to support the failing liver. Over the years, the development of bioartificial liver-assist devices has aimed at replacing the three main functions of hepatocytes, which are synthetic, metabolic, and excretory. The application of porcine hepatocytes in humans to carry out biotransformation, as well as other metabolic functions and refinement of the membrane separator, have yielded some promising results in supporting patients with acute liver failure. Further advances will need to be made before these bioartificial devices can be considered for routine application in clinical settings.

Human hepatocytes produce an isoform of FAS that inhibits apoptosis

BACKGROUND

Fas (Apo-1/CD95), a member of the tumor necrosis factor receptor family, can mediate apoptosis when engaged by its ligand or by anti-Fas antibody. Fas is expressed by cells of the immune system and by some nonlymphoid tissues. Numerous studies have suggested that the Fas pathway may play a role in the rejection of allografts. Functional, soluble forms of the Fas receptor are produced by activated peripheral blood mononuclear cells and some transformed cell lines. The purpose of this study was to determine if soluble variants of Fas are produced in the liver and to determine if blockade of the Fas pathway, by liver-derived soluble Fas, inhibits Fas-mediated apoptosis.

METHODS

Liver and purified hepatocyte specimens were analyzed for Fas transcripts by reverse transcriptase-polymerase chain reaction with primers that span the transmembrane region of the molecule. Bile and cell lysates were analyzed for soluble Fas by specific enzyme-linked immunosorbent assay. Lysates were prepared from normal liver and hepatocytes and utilized to block Fas-mediated apoptosis of Jurkat cells as determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and flow cytometry.

RESULTS

A variant form of Fas is abundantly expressed in normal liver and purified hepatocytes. This variant form of Fas is expressed in all normal liver specimens but only in half of the liver specimens obtained during allograft rejection. The levels of soluble Fas diminish in patients undergoing liver allograft rejection in contrast to patients with stable grafts. Importantly, a soluble form of Fas is produced in the liver by hepatocytes and can specifically inhibit Fas-mediated apoptosis.

CONCLUSION

These data raise the possibility that soluble Fas, produced by hepatocytes, may influence the immune response by blocking Fas-mediated apoptosis and, thus, may have a role in liver transplantation.

[Assessment of fetal maturation by epithelial growth factor in serum of pregnant women]

OBJECTIVE

To study the concentrations of human epithelial growth factor (EGF), progesterone (P) in serum, and EGF, P, amylase (Ams), creatinine (Cr) and total bilirubin (TB) in amniotic fluid at different trimester normal pregnancy.

METHODS

The concentrations of EGF, P in serum of 181 cases of pregnant women (first trimester 35, midtrimester 69, late trimester 77) and the concentrations of EGF, P, Ams, Cr, TB in amniotic fluid of 87 cases (mid-trimester 44, late trimester 43) were determined. At the same time, the concentrations of EGF, P in serum of umbilical veins and arteries from 23 full term neonates were determined as well. The concentrations of EGF and P were measured by radioimmunoassay and Ams, Cr, TB in amniotic fluid by PA110 autobiochemistry analyzer.

RESULTS

(1) The concentrations of EGF, P in serum increased as pregnancy advanced. (2) There were significant correlations between EGF level and Ams, Cr levels in amniotic fluid. After 32 gestational weeks, the fetal maturity rate was 70.59% when EGF was > or = 4.5 micrograms/L. There were significant positive correlations between EGF in maternal serum and in amniotic fluid, (3) The maternal serum EGF concentration was significantly higher than that in the umbilical vessels, and there was positive correlations between them.

CONCLUSION

The change of maternal serum concentration could be used to determine the fetal maturation.

[Determination of the soluble non-starch polysaccharides in rice and wheat bran by gas chromatography]

Cereal polysaccharides can be broadly classified into two distinct and chemically well-defined types. They are the storage polysaccharides (alpha-glucan) and the structural polysaccharides starch (beta-glucan) which are usually called non-starch polysaccharides (NSP). The determination of soluble non-starch polysaccharides in rice and wheat bran by gas chromatography has been developed. The free sugars in the sample were extracted with 80% ethanol. The residue was hydrolyzed in an acetic acid buffer solution (pH 5.0) in the presence of amylase and amyloglucosidase to remove starch. The soluble NSP obtained was further hydrolyzed in the acidic condition to produce the corresponding monosaccharides which were derivatized to form alditol acetates for GC analysis with allose as the internal standard. The GC conditions were OV-1701 column (25 m x 0.3 mm) with temperature program from 195 degrees C to 225 degrees C and FID.

Current status of living-related liver transplantation

Living-related liver transplantation has come of age. This manuscript addresses the most important facets of the living-related liver transplant procedure including selection of the donor, the recipient operation, immunosuppression and rejection as well as the most common surgical complications. It also describes the results in terms of patient and graft survival, retransplantation and quality of life. Although living-related liver transplantation has not solved the problem of organ shortage, it has provided many children with an opportunity to live and enjoy life.

Rationale for treatment design: biochemical modulation of 5-fluorouracil by leucovorin

Preclinical in vitro and in vivo results have demonstrated the conditions required for optimal modulation of 5-FU activity by LV. The ability to increase intracellular concentrations of higher chain length polyglutamates was a function of duration of longer exposure to LV rather than the dose. In rats bearing advanced colorectal tumors, the role of LV dosage was more clearly evident with the weekly 5-FU treatment schedule than with the daily schedule. Phase III clinical trials in patients with advanced colorectal cancer demonstrated that low-dose and high-dose LV (daily x 5) and weekly high-dose LV schedules yielded similar response rates with different toxicity profiles. A phase III trial demonstrated significant therapeutic advantages for a bimonthly schedule of high-dose LV over a monthly schedule of low-dose LV. Taken together, these results provide insight into LV biomodulation, but the optimal conditions for these regimens for individual patients remain undetermined. To date it has not been possible to identify the optimal conditions for modulation of 5-FU by LV in individual patients with advanced colorectal cancer, and response rates are comparable. A regimen that offers the opportunity to manage treatment-induced toxicity is recommended. With diarrhea being the primary dose-limiting toxicity with the weekly 5-FU and high-dose LV (manifested during the 2-3 weeks of treatment), management of toxicity can be achieved by delaying treatment, by dose reduction, and/or by treatment with octreotide47 without compromising efficacy. In contrast, with the daily x 5 schedule, multiple toxicities (mucositis [stomatitis], diarrhea, neutropenia, and hand and foot syndrome) are manifested regardless of the dose of LV administered. An additional advantage to the weekly schedule is that it provides the opportunity to use 5-FU/LV treatment in sequence or combination with other drugs, such as topoisomerase I inhibitors (CPT-11), antifolates (methotrexate, trimetrexate), and platins (oxaliplatin).

Expression of functional domain of chicken gizzard calponin

A full-length cDNA of the function domain of wild-type chicken gizzard calponin was cloned into expression vector pAED4 and the recombinant function domain of wild-type calponin was expressed in an Escherichia coli expression system. The actin domain of calponin (CaP-B) can bind with actin and it is a requisite for its inhibition of ATPase and vasoconstriction of smooth muscle. In this study, the cDNA of CaP-B was inserted into vector pAED4 by direction-cloning method. The cDNA of CaP-B was obtained with PCR cloning technique. The recombinant DNA pAED4-Cap-B was transformed into E. coli BL21 (DE3) and identified with the restriction analysis. The bacterial clones containing transformants were induced to be highly expressed in E. coli BL21 (DE3). The target protein was detected and identified by Western Blot analysis. The content of target protein was as high as 10% of the whole protein after overnight (16 h) culture. The results confirmed that Cap-B was relatively highly expressed in E. coli.

Deletion in poly(ADP-ribose)polymerase pseudogene and lung cancer risk

The poly(ADP-ribose)polymerase (PADPRP) gene has been implicated in carcinogenesis through its role in DNA repair, replication and recombination. A two-allele polymorphism in the chromosome 13 PADPRP pseudogene has been studied in several racial groups. It has been suggested that the B allele, which results from a 193-bp deletion in the gene, predisposes to myeloma in Blacks. We assessed the association between chromosome 13 PADPRP pseudogene genotype, mutagen sensitivity (a marker reflecting host DNA repair capability), cigarette smoking, and lung cancer risk in a minority lung cancer case-control study. The chromosome 13 PADPRP pseudogene polymorphism was detected by polymerase chain reaction-based analysis. Mutagen sensitivity was measured by an in vitro assay that quantified bleomycin-induced chromatid breaks in peripheral blood lymphocyte cultures. We examined 121 cases (80 African-Americans and 41 Mexican-Americans) with previously untreated lung cancer and 171 matched controls. Our results suggested that the distribution of the PADPRP pseudogene genotype frequencies was significantly different among African-American and Mexican-American controls (P < 0.001). The susceptibility genotype (i.e. at least one B allele) was found in 82.5% of African-American cases, 79.4% of African-American controls, 53.7% of Mexican-American cases, and 32.4% of Mexican-American controls. The odds ratios (OR) and 95% confidence intervals for the PADPRP susceptibility genotypes were 2.3 (95% CI = 0.7-8.0) and 3.2 (95% CI = 1.0-10.3) for African-Americans and Mexican-Americans respectively, after adjustment by age, sex, pack-years and mutagen sensitivity. Patients with the susceptibility genotype appeared to have more mutagen-induced breaks than did patients with the other genotype. Only adenocarcinoma was significantly associated with the PADPRP susceptibility genotype (OR = 3.8). Mutagen sensitivity (> or = 1 break/cell) was significantly associated with lung cancer risk for both ethnic groups with increased ORs of above three-fold. On stratified analysis, synergistic interactions were noted for the PADPRP susceptibility genotype, mutagen sensitivity and smoking status. In Mexican-Americans, the ORs for PADPRP susceptibility genotype, mutagen sensitivity and both risk factors combined were 1.3, 2.7 and 17.1 respectively. The combined OR for the PADPRP susceptibility genotype and smoking status was 15.6. Therefore, this polymorphism appears to be associated with lung cancer risk. However, it is likely that no single genotype is sufficiently predictive of risk and that a panel of susceptibility markers is needed to define the high-risk subgroup.

Comparative antitumor efficacy of docetaxel and paclitaxel in nude mice bearing human tumor xenografts that overexpress the multidrug resistance protein (MRP)

BACKGROUND

Multidrug resistance has been associated with expression of the multidrug resistance protein (MRP). Recently, MRP-expression has been detected in human tumor samples of patients with breast cancer and non-small-cell lung cancer. Since taxoids are the most active drugs in the treatment of both tumor entities, the antitumor efficacies of paclitaxel and docetaxel were compared in nude mice bearing human tumor xenografts that express MRP.

MATERIALS AND METHODS

Athymic nude mice (nu/nu) bearing tumor xenografts of parental human sarcoma HT1080 or MRP-expressing HT1080/DR4 cells (as confirmed by Northern blot analysis) were treated with the maximum tolerated doses (MTD) of doxorubicin ([Dx] 10 mg/kg i.v. push), paclitaxel ([PC] 50 mg/kg three-hour i.v. infusion), or docetaxel ([DC] 40 mg/kg three-hour i.v. infusion). In vitro, the activity of doxorubicin, paclitaxel and docetaxel was evaluated by the sulphorhodamine B (SRB) assay using the pyridine analogue PAK-104P (5 microM), a potent inhibitor of MRP-function.

RESULTS

At their MTDs both taxoids showed significant activity against MRP-negative HT1080 xenografts with response rates of 80% (40% CR) for PC and 100% (60% CR) for DC. In contrast, DC was significantly more active than PC in nude mice bearing doxorubicin resistant MRP-expressing HT1080/DR4 tumor xenografts (overall response rates: 100% (60% CR) for DC; 10% (0% CR) for PC; 0% for Dx). Since treatment of mice with the MTD of PC or DC yielded similar overall toxicity (maximum weight loss for HT1080: PC 8.6 +/- 2.2%; DC 7.5 +/- 2.2% and for HT1080/DR4: PC 11.6 +/- 3.0%; DC 7.6 +/- 1.8%, respectively), these results demonstrate the increase in the therapeutic index for docetaxel against MRP-expressing tumors. In vitro, HT1080/DR4 cells were 270-fold, 6.4-fold and 2.8-fold more resistant than parental cells to doxorubicin, PC and DC, respectively. Pyridine analogue PAK-104P completely restored drug sensitivity to PC and DC, while no effect of PAK-104P on parental HT1080 cells was observed.

CONCLUSIONS

Both taxoids, when given at their MTDs, showed significant efficacy against parental HT1080 tumor xenografts. However, docetaxel at its MTD was significantly more active against MRP-expressing tumor xenografts than paclitaxel. Furthermore, in vitro resistance of HT1080/DR4 cells was higher for PC (6.4-fold) than for DC (2.8-fold). Since PAK-104P completely restored sensitivity to both taxoids, the observed resistance appears to be related to MRP. These data suggest, that docetaxel is not as readily transported by MRP as paclitaxel leading to an increased therapeutic ratio in MRP-expressing tumors in vivo. Therefore, docetaxel may have therapeutic advantages in the clinical treatment of MRP-expressing tumors.

Detection of yellowhead virus and Chinese baculovirus in penaeid shrimp by the Western blot technique

The continuing threat posed by viral diseases in cultured shrimp calls for the development of detection technologies for monitoring the animals, especially broodstock. Two of the most highly pathogenic viruses of penaeid shrimp are the yellow-head virus (YHV) and Chinese baculovirus (CBV, also called white spot baculovirus). A Western blot (WB) protocol capable of detecting YHV and CBV in the hemolymph of infected shrimp was developed. The use of the hemolymph as material for virus detection allowed for sample collection without sacrificing the animals. This protocol was highly specific, rapid, and sensitive enough to detect the presence of the viruses before the appearance of overt symptoms. It was also useful for demonstrating the growth of both viruses in primary shrimp lymphoid cell cultures.

[The expression of calponin in Oddi's sphincters and its actions during gallstone formation]

OBJECTIVES

To study on the expression of calponin in an animal model of gallstone disease and investigate the molecular mechanisms of gallstone formation.

METHODS

After feeding a high-cholesterol diet to guinea pigs, Oddi's sphincters were disseced on day 30 and day 60 respectively. We used RT-PCR, western-blotting to evaluate expression level of calponin gene.

RESULTS

Down-regulation of calponin gene expression was observed in animals with gallstone. The levels of both protein and mRNA expression for calponin on day 30 and day 60 were lower than those of control group with the level from day 60 lower than that from day 60, while myosin expressions were relatively stable.

CONCLUSION

Our results indicated that the decrease of calponin could increase the pressure of sphincter of Oddi, aggravate the stasis of bile and promote the gallstone formation.

[Correlation analysis of radiation effects on potential doubling time (Tpot) for human nasopharyngeal carcinoma cells]

OBJECTIVE

To understand radiation-induced cell kinetic changes of human nasopharyngeal carcinoma CNE cells and clarify cell biology basis of repopulation.

METHODS

Either exponential growing stage or plateau stage human nasopharyngeal carcinoma CNE cells were measured by BrdUrd/DNA bivariate flow cytometry for phase fraction, BrdUrd labeling index, S phase duration, potential doubling time (Tpot), etc. Correlation analysis of Tpot with other kinetic parameters was made.

RESULTS

(1) For exponentially growing CNE cells, shortening of Tpot after irradiation was closely correlated with increased BrdUrd labeled S phase fraction (P < 0.05), whereas no correlation was found between Tpot and other kinetic parameters measured; (2) for plateau stage CNE cells, shortening of Tpot with various radiation doses was closely correlated with decreased G0/G1 phase fraction (P < 0.05) and increased G2M phase fraction (P = 0.002), whereas no correlation was found between Tpot and other parameters measured.

CONCLUSION

In a range of 0-8 Gy of irradiation, an increased accelerated repopulation rate was resulted from increasing radiation dose. Recruitment of G0 cells into cell cycle might play a major role in radiation-induced accelerated repopulation for plateau stage CNE cells, while it was contributed by an increased DNA synthesis manifested by an increased BrdUrd labeled S phase fraction for exponential growing CNE cells.

Epstein-Barr virus lymphoproliferative disorders after liver transplantation

Post-transplant lymphoproliferative disorders (PTLD) represent a spectrum of histological and immunological abnormalities, ranging from benign polyclonal B-cell hyperplasia to monoclonal malignant lymphoma. The important role of Epstein-Barr virus (EBV) in PTLD in liver transplant patients, particularly in pediatric recipients, is reviewed. Understanding the risks of EBV infection, the clinical presentations and diagnosis of PTLD, and its pathophysiology are crucial to the management of these disorders. Current treatment methods have resulted in better outcomes of these disorders, which in the past were uniformly fatal.

Potential effect of cyclosporin A in formation of cholesterol gallstones in pediatric liver transplant recipients

Recent advancements in liver transplantation have resulted in extended survival both for grafts and recipients. Such improvement, together with the shortage of donor organs has prompted expansion of the donor pool to include less than ideal donors, especially in life-threatening situations. The use of older liver donors has been associated with lower long-term survival. However, potential morbidity such as gallstone formation has not been explored. We analyzed bile composition in a child who developed cholesterol gallstones in the proximal bile duct two years after undergoing emergency liver transplantation with a liver from a 78-year-old donor. Oral administration of ursodeoxycholic acid (ursodiol) shifted the cholesterol composition of the bile from a supersaturated, potentially crystallized state to a liquid (micellar) state. Unlike cyclosporin A, FK506 showed an increase in the proportion of chenodeoxycholic acid and a decrease in the proportion of cholic acid, and thus may exhibit minimal or no hepatotoxic effect. Thus, in donor livers with factors known to be associated with cholesterol gallstone formation (such as age, sex, or obesity), one may consider analyzing the bile composition at the time of procurement. Depending on cholesterol and bile acid composition the use of FK506 with or without addition of ursodeoxycholic acid may be warranted.

The study on the relationship between the expression of calponin and gallstone formation

In order to understand the molecular mechanisms of gallstone formation, the expression of calponin in animal model of gallstone disease was studied. High-cholesterol diet was given to the guinea pigs to induce gallstone formation. RT-PCR and Western-blotting were used to evaluate expression level of calponin gene. Down-regulation of calponin gene expression was observed in animals with gallstone, while myosin expression was relatively stable. Our results indicated that the decrease of calponin could increase the pressure of Oddi's sphincter, aggravate the stasis of bile and promote the gallstone formation.

Thymidylate synthase inhibitors in cancer therapy: direct and indirect inhibitors

PURPOSE AND METHODS

Although fluoropyrimidines, in particular, fluorouracil (5-FU) and fluorodeoxyuridine (FdUrd), are active alone and in combination with other agents in a variety of human malignancies, therapeutic selectivity, resistance, and efficacy have been a major limitation in cancer therapy. Preclinical and clinical results in advanced and adjuvant colorectal cancers confirmed that the therapeutic efficacy of fluoropyrimidines, with thymidylate synthase (TS) as a primary target, can be improved significantly with leucovorin (LV) modulation. With the recognition that TS is an important therapeutic target, direct and specific inhibitors have been developed and are under intensive preclinical and clinical evaluation, primarily in patients with colorectal cancer, with demonstrable activity. The direct TS inhibitors have been shown to be potent, with a high level of specificity under therapeutic conditions for TS. This includes ZD1694, AG337, and LY231514. To date, although the therapeutic activity of both direct and indirect inhibitors of TS is similar, differences in the magnitude and profile of toxicity have been observed. A phase III comparative evaluation of a direct inhibitor of TS (ZD1694) with an indirect inhibitor (5-FU/LV) has been completed and showed similar activity but reduced toxicity in favor of ZD1694.

RESULTS

Recognition that greater than 95% of the injected dose of 5-FU is rapidly inactivated by dihydropyrimidine dehydrogenase (DPD) to therapeutically inactive products, but with toxicity to normal tissues, led to the development of inhibitors of this enzyme with the aim to modify the therapeutic index of 5-FU. Several inhibitors in combination with 5-FU are under preclinical and clinical evaluation, including uracil and 5-chloro-2,4-dihydroxy pyridine, as modulators of 5-FU derived from its prodrug tegafur and 5-ethynyluracil as a modulator of 5-FU.

CONCLUSION

In this review, an update of the present status of direct and indirect inhibitors of TS is discussed, as well as the future prospect for new drugs alone and in combination.

Emergency transjugular intrahepatic portosystemic shunt (TIPS) in an infant: a case report

Since the first successful report regarding the feasibility of transjugular intrahepatic portosystemic shunt (TIPS) as an alternative to surgical decompression of portal hypertension, this method has been used extensively as a temporizing measure in controlling refractory variceal bleeding before liver transplantation in adults with cirrhosis. There are few reports of TIPS in pediatric patients because variceal bleeding in most of these patients can often be managed conservatively without invasive intervention. Recently, successful use of TIPS to treat complications of portal hypertension has been described in two children ages 10 and 13. To our knowledge, there are no reports of TIPS used in infants under the age of 1 year. The authors report a case in which TIPS was used to successfully control variceal bleeding in a 10-month-old infant before consideration for hepatic transplantation.

d,l-buthionine-(S,R)-sulfoximine potentiates in vivo the therapeutic efficacy of doxorubicin against multidrug resistance protein-expressing tumors

Intracellular glutathione (GSH) has been implicated as a regulatory determinant of multidrug resistance protein (MRP) function. The objective of the present study was to evaluate in vivo the ability of d,l-buthionine-(S,R)-sulfoximine (d,l-BSO), a potent inhibitor of GSH biosynthesis, to reverse MRP-mediated drug resistance to doxorubicin. Athymic nude mice (nu/nu) bearing advanced parental human fibrosarcoma HT1080 and MRP-expressing HT1080/DR4 tumors were treated with the maximum tolerated dose of doxorubicin (10 mg/kg, i. v. push). This therapy produced an overall response rate of 50% (20% complete response and 30% partial response) in mice bearing parental HT1080 xenografts, whereas no significant antitumor activity against HT1080/DR4 tumors was observed. Treatment of mice bearing HT1080 and HT1080/DR4 xenografts with a continuous i.v. infusion of nontoxic doses of d,l-BSO (300 and 600 mg/kg/day) produced a 60% reduction of GSH plasma levels and greater than 95% reduction in GSH tumor levels in both parental and multidrug-resistant tumors; however, this treatment possessed no in vivo antitumor activity by itself. Under these treatment conditions, a combination of d,l-BSO with the maximum tolerated dose of doxorubicin administered at 24 h during a 48-h i.v. infusion of d,l-BSO completely restored the response of MRP-expressing HT1080/DR4 tumors to doxorubicin (overall response rate, 63%; complete response rate, 38%) with no potentiation of host toxicity. The d,l-BSO-induced in vivo reversal of MRP-mediated drug resistance correlated in vitro with the restoration of intracellular doxorubicin retention in cultured HT1080/DR4 cells. Depletion of GSH by d,l-BSO in drug-sensitive HT1080 tumors that do not express MRP did not alter the in vivo response to doxorubicin. Using the same treatment schedule, dose, and administration of doxorubicin with and without d,l-BSO in nude mice bearing P-170 glycoprotein-expressing A2780/Dx5 tumors, no potentiation of the therapeutic index of doxorubicin was found, demonstrating the in vivo selectivity of d, l-BSO-induced GSH depletion on MRP-function. The data reported herein indicate that in vivo function of MRP as a mediator of doxorubicin resistance requires the presence of sufficient GSH pools. d,l-BSO may provide an example of an effective in vivo modulator of MRP-mediated drug resistance.

Elevations in IFN-gamma, IL-5, and IL-10 in patients with the autoimmune disease primary biliary cirrhosis: association with autoantibodies and soluble CD30

Antimitochondrial antibodies (AMA) which recognize the E2 component of the pyruvate dehydrogenase complex are found in virtually all patients with the autoimmune liver disease primary biliary cirrhosis (PBC). The factors that contribute to elevated AMA and the relationship of the autoantibodies to disease pathogenesis have not been elucidated. Since cytokines are important regulators of antibody production and isotype switching, the association of specific cytokines to antibody production was examined in patients with PBC. Elevations in IL-2, IFN-gamma, IL-4, IL-5, and IL-10 were detected in serum from patients with PBC. However, only IFN-gamma (6012 +/- 1128 pg/ml vs 147 +/- 89 pg/ml, P < 0.0001) and IL-5 (382 +/- 103 pg/ml vs 29 +/- 12 pg/ml, P < 0.001) were significantly elevated compared to normal controls. Moreover, there was a positive correlation in the levels of IFN-gamma, and to a lesser extent IL-5, with the levels of soluble CD30 (sCD30) in the circulation. The elevated levels of sCD30 detected in patients with PBC (194 +/- 29 U/ml vs 39 +/- 9 U/ml in normal controls) suggest that CD30+ cells may produce cytokines, which contribute to the immune abnormalities in patients with PBC.

Role of fluoropyrimidine Schedule and (6R,S)leucovorin dose in a preclinical animal model of colorectal carcinoma

BACKGROUND

Fluorouracil (5-FU) and 5-fluoro-2'-deoxyuridine (FdUrd), used alone or in combination with other cytotoxic agents, exhibit limited efficacy in the treatment of advanced gastrointestinal cancer. (6R,S)leucovorin (LV), a source of reduced folate cofactor, can modulate (i.e., enhance) the therapeutic efficacy of treatment with these fluoropyrimidines (FPs). The role of FP schedule and lv dose in modulating FP antitumor activity, using clinically relevant drug doses and schedules, has not been fully documented.

PURPOSE

We evaluated the antitumor activities and the toxic effects of 5-FU and FdUrd, used either alone or in combination with LV, by following three clinically relevant treatment schedules in rats bearing advanced ward colorectal carcinomas.

METHODS

Maximum tolerated doses (MTDs), i.e., doses producing a reversible body weight loss of no more than 20% with no lethality, of 5-FU and FdUrd, either individually or in combination with LV, were used in the following treatment schedules: (I) 4 days of continuous intravenous FP infusion (with or without a daily 2-hour lv infusion); (II) a daily FP intravenous push for 4 days (LV, when given, was administered as a 2-hour infusion, with the FP push given after the first hour of LV treatment); and (III) an FP intravenous push given weekly for 3 weeks (the coadministration of LV and FP was performed as in schedule II). In these studies, LV was given at either a low dose (20 mg/kg [body weight] per day) or a high dose (200 mg/kg per day). The MTDs of 5-FU and FdUrd, with or without LV, were defined in normal rats. Antitumor activities were assessed in animals 12-14 days after they received subcutaneous tumor implants. Toxic effects at the MTD were evaluated in both normal and tumorbearing animals.

RESULTS

With schedules I and II, the MTD of 5-FU alone was 35 mg/kg per day; with schedule III, it was 100 mg/kg per week. For FdUrd alone, the MTD was 100 mg/kg per day with schedules I and II and 400 mg/kg per week with schedule III. Coadministration of LV reduced the MTD of both 5-FU and FdUrd by approximately 25%-30%, irrespective of the LV dose used. The dose-limiting toxic effects of treatment with 5-FU and FdUrd were diarrhea and/or stomatitis, the relative severity of which depended on the schedule of FP administration. The profile of toxic effects was not altered by LV when used at either dose. FP antitumor activity was modulated by LV in all three treatment schedules, but the greatest effects were seen using schedule III, where more complete tumor regression was seen with high-dose LV than with low dose LV. LV potentiated the antitumor activity of FdUrd to a greater extent than that observed with 5-FU.

CONCLUSIONS

In this rat model of colorectal carcinoma, the extent to which FP antitumor activity is modulated by LV depends on the schedule of FP administration and the dose of LV used.

Polyglutamylation of the dihydrofolate reductase inhibitor gamma-methylene-10-deazaaminopterin is not essential for antitumor activity

As part of a continuing program aimed at developing nonpolyglutamylatable inhibitors of dihydrofolate reductase that are less toxic and more specific in their action, we herein report the therapeutic efficacy and toxicity of gamma-methylene-10-deazaaminopterin (MDAM) in athymic nude mice bearing advanced human HCT-8 ileocecal xenografts and its antitumor activity in C57BL/6 x DBA/2 F1 (hereafter called B6D2F1) mice bearing P388 murine leukemia. For the xenograft study, MDAM was administered at the maximum tolerated dose by the following dose schedules: (a) 5-day continuous i.v. infusion at 1.0 mg/kg/day (schedule I); and (b) i.v. push, daily for 5 days at 50 mg/kg/day (schedule II). The maximum tolerated dose values for methotrexate (MTX) under these conditions were 0.2 and 1.0 mg/kg/day for schedule I and schedule II, respectively. MTX did not exhibit any significant antitumor activity in this model system by both schedules; however, MDAM induced complete responses of 13 and 25% and partial responses of 25 and 50% by schedules I and II, respectively. MDAM also exhibited antitumor activity significantly superior to that of MTX in the P388 tumor model. One of the enantiomers of MDAM, which possesses the natural configuration at the gamma-methyleneglutamate moiety (l-MDAM), has been shown to be a better inhibitor of human recombinant dihydrofolate reductase and H35 hepatoma cell growth than D,L-MDAM. L-MDAM inhibited the uptake of radiolabeled folinic acid to H35 hepatoma cells eight times more efficiently than MTX. The results indicate that the superior activity of MDAM relative to MTX may be partially due to a combination of enhanced transport to tumor cells and slower deactivation by aldehyde oxidase.

[Reversion of malignant phenotypes of human lung squamous carcinoma cells by ornithine decarboxylase antisense RNA]

Abnormally elevated activity of ornithine decarboxylase (ODC), with subsequent polyamine accumulation are intimately associated with the genesis, development and metastasis of cancer. Therefore, ODC antisense RNA was used to transfect human lung squmous carcinoma cell line LTEP-78. Compared with the parental cells, growth of the antisense transfected LTEP-78 cells arrested in G0/G1 phase and colony formation in soft agar and tumorigenicity in nude mice were significantly reduced. Nucleic acid hybridization demonstrated the expression of ODC antisense RNA and the content of ODC mRNA was markedly reduced. The results suggest that the reversion of malignant phenotypes of human lung squamous carcinoma cells is associated with the control of polyamine biosynthesis.

PAK-104P, a pyridine analogue, reverses paclitaxel and doxorubicin resistance in cell lines and nude mice bearing xenografts that overexpress the multidrug resistance protein

Multidrug resistance (MDR) is considered multifactorial and has been associated with overexpression of the multidrug resistance protein (MRP). However, effective compounds for reversal of MRP-related MDR are limited. In the present study, the modulatory activity of the novel pyridine analogue PAK-104P on MRP-mediated resistance to doxorubicin and paclitaxel was investigated in two doxorubicin-selected human tumor cell lines [HT1080/DR4 (sarcoma) and HL60/ADR (leukemia)] and compared with the nonimmunosuppressive cyclosporine analogue PSC-833. In cell lines HT1080/DR4 (MRP/lung resistance-related protein phenotype) and HL60/ADR (MRP phenotype), doxorubicin resistance was significantly higher (250-fold and 180-fold, respectively) than that to paclitaxel (6-fold and 9-fold, respectively). With noncytotoxic concentrations of PAK-104P (1 and 5 microM), the reversal of doxorubicin resistance was significant but partial in HT1080/DR4 and HL60/ADR cells (dose-modifying factor for 5.0 microM PAK-104P, 25.0 and 31.2, respectively), whereas complete reversal of paclitaxel resistance was achieved in HL60/ADR cells. In contrast, PSC-833 modulation of doxorubicin and paclitaxel resistance was modest. Cellular drug uptake and retention studies by flow cytometry analysis demonstrated that PAK-104P was effective in restoring cellular doxorubicin concentrations in resistant cells to levels comparable to those obtained in parental cells. In athymic nude mice, PAK-104P significantly potentiated the therapeutic efficacy of doxorubicin and paclitaxel against resistant HT1080/DR4 xenografts. Of significance is that the maximum tolerated doses of doxorubicin and paclitaxel were administered in combination with PAK-104P, documenting improvement in the therapeutic index of these agents. In addition to reversing P-glycoprotein-mediated MDR, the pyridine analogue PAK-104P provides an example of an effective in vivo modulator of MRP-mediated MDR.

5-Ethynyluracil (776C85): effects on the antitumor activity and pharmacokinetics of tegafur, a prodrug of 5-fluorouracil

We studied the effects of 5-ethynyluracil (776C85 and 776C), a potent mechanism-based inactivator of dihydropyrimidine dehydrogenase, on the antitumor efficacy and pharmacokinetics of tegafur (FT), a prodrug of 5-fluorouracil (5-FU), in rats with large s.c. colon carcinoma. Rats were dosed p.o. once daily for 7 days with either FT, FT and uracil in a 1:4 molar ratio (UFT), FT 1 h after 776C (776C/FT), or UFT 1 h after 776C (776C/UFT). 776C, which was dosed at 1 mg/kg, had neither intrinsic antitumor activity nor toxicity. The rank order in antitumor efficacy at the maximal tolerated dose of the FT (mg/kg/day) component was 776C/FT (5 mg/kg/day) > or = UFT (80 mg/kg/day) = 776C/UFT (5 mg/kg/day) >> FT (200 mg/kg/day). One-hundred % of rats treated with 776C/FT had complete and sustained tumor regression with no severe toxicity. The area under the plasma 5-FU concentration versus the time curve generated from UFT, FT, and 776C/FT at their maximum tolerated dose was 140, 50, and 27 microM.h, respectively. The area under the concentration in plasma versus time curve did not correlate with the rank order of antitumor efficacy. The vast majority of 5-FU derived from FT (alone) appeared to be rapidly catabolized. Furthermore, plasma exposure of 5-FU derived from UFT was more variable than that from 776C/FT. Each therapy also produced different levels of plasma uracil. Endogenous plasma uracil levels (1-3 microM) were not affected by FT but increased to 100 microM after dosing with 776C. Plasma uracil from UFT was 800 microM 1 h after dosing. These results suggest that moderately elevated uracil (776C/FT) may be beneficial, whereas uracil that is greatly elevated during the first 5 h (UFT) and 5-FU catabolites (FT alone) may interfere with antitumor efficacy. 776C, coadministered with FT, could provide once-a-day oral therapy for cancer patients.

5-Fluorouracil prodrug: role of anabolic and catabolic pathway modulation in therapy of colorectal cancer

Following p.o. administration to rats bearing advanced colorectal carcinoma, Ftorafur (FT) is converted to 5-fluorouracil (FUra) by microsomal P450 in the liver. To optimize the therapeutic selectivity of the FUra generated from FT, three approaches were utilized: (a) inhibition of FUra degradation to dihydrofluorouracil by uracil as an alternative substrate for uracil reductase in the molar ratio of 4 uracil:1 FT (UFT); (b) modulation of drug inhibition of thymidylate synthase by leucovorin (LV); and (c) by increasing the level of FUra incorporation into cellular RNA by N-(phosphonacetyl)-L-aspartate (PALA), an inhibitor of aspartate transcarbomylase. The maximum tolerated dose (MTD) of FT and UFT, administered 3 times a day for 28 days, was 150 mg/kg/day and 60 mg/kg/day, respectively. The MTDs were not significantly modified by LV (150 or 600 mg/kg/day), administered by the p.o. route with the drugs, or by PALA (100 mg/kg) administered weekly by the i.v. route. The dose-limiting toxicity of FT alone and in combination with the modulators was stomatitis. The severe alopecia observed with FT alone was reduced significantly by uracil. At the MTD, the antitumor activity of UFT was superior to those of FT and FUra alone and in combination with LV and/or PALA. The 3-month sustained complete tumor regression for UFT, FT, and FUra was 38%, 0%, and 13% (for the weekly schedule), respectively. Although uracil, LV, and PALA individually increased the antitumor activity of FT at its MTD, the combination of the three modulators produced the highest therapeutic efficacy in rats bearing advanced colorectal carcinoma, in which 100% of the treated animals achieved complete and sustained tumor regression. The therapeutic efficacy observed with FT modulation could not be achieved with FUra administered by different schedules, each at its MTD alone or in combination with either LV or PALA. In brief, modulation of FT produced greater therapeutic efficacy and selectivity than FUra. Furthermore, the combined use of modulators capable of inhibiting the degradation pathway of FUra and potentiating the effects of the anabolic metabolites action appears to offer the greatest therapeutic potential.

[Clinical application of luteinizing hormone releasing hormone agonist and its impact on bone metabolism]

OBJECTIVES

To evaluate the efficacy of luteinizing hormone releasing hormone agonist (LHRH-A) in the treatment of endometriosis (Em), uterine leiomyoma and adenomyosis, and its impact on bone metabolism.

METHODS

Twenty patients, Em 13 (stage II4, III7, IV2), leiomyoma 4 and adenomyosis 3, were selected to receive LHRH-A 200 micrograms intramuscular daily for 3 months. Clinical and ultrasound features serum follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), osteocalcin (BGP) concentrations were compared before and at the end of treatment. Furthermore, 24-hour urinary calcium (Ca), phosphate (P) excretions and bone mineral density (BMD) of radius and lumbar spine measured by single photon absorptiometry (SPA) and dual energy X-ray absorptiometry (DEXA) were also analysed before and at the end of treatment. Patients were followed-up 3-19 months after discontinuation of the drug.

RESULTS

At the end of treatment dysmenorrhea disappeared in all 15 cases. Pelvic tenderness and induration improved in 18, endometrioma shrinked in 13 cases. Mean uterine volume of 7 patients with leiomyoma or adenomyosis was reduced by 35% from the basal volume. Serum LH, E2 levels were suppressed significantly (P < 0.05), mean E2 concentration declined from 459.5 +/- 292.0 to 160.3 +/- 110.7 pmol/L (P < 0.001). No significant change was found in serum BGP, urinary Ca, P, and BMD of radius and lumbar spine at the end of therapy, The only side effect was mild not flushes and sweating during treatment. After stopping the drug, 17 patients resumed menses within 2 months. Dysmenorrhea and pelvic mass recurred in 6 months with less severity. One became pregnant in 3 months.

CONCLUSIONS

LHRH-A administration is effective in the treatment of Em, leiomyoma and adenomyosis. No significant adverse effect was shown on bone metabolism at the end of 3-month therapy.

Electric acupuncture treatment of peripheral nerve injury

54 cases of peripheral nerve injury were treated by electric acupuncture and compared with 54 control cases treated with supportive medication. The changes after treatment were observed chiefly by electromyography while sensory and motor improvement were also recorded as auxiliary indicators. The therapeutic results in the acupuncture group were 5 cases cured, 26 markedly effective, 19 improved, and 4 cases failed, a total effective rate of 92.6% in contrast to the 55.6% for the controls. Analysis of the therapeutic results showed that 1) those in the acupuncture group were significantly better than in the control group; 2) nerve injuries should be treated as early as possible; 3) the radial nerve and the common peroneal nerve recovered faster than others; 4) cases not surgically explored recovered faster than those that were, and 5) patients with prompt propagation of the needling sensation recovered significantly faster than those with slow propagation.

Modulation of the antitumour activity of cisplatin alone and in combination with 5-fluoro-2'-deoxyuridine by N-phosphonacetyl-L-aspartate in murine colon carcinoma no. 26

Modulation of the therapeutic efficacy of cisplatin (CDDP) and 5-fluoro-2'-deoxyuridine (FdUrd) alone and in combination with N-phosphonacetyl-L-aspartate (PALA) was evaluated in mice bearing colon carcinoma (C-26) using a weekly intravenous (i.v.) push schedule for 3 weeks. A non-toxic dose of PALA (100 mg/kg) was administered i.v. 24 h prior to the i.v. administration of CDDP +/- FdUrd. The maximum tolerated doses (MTD) of CDDP and FdUrd when used as a single agent were 9 and 400 mg/kg, respectively. In combination, however, the MTD of CDDP and FdUrd were 2.5 and 300 mg/kg, respectively. PALA did not significantly affect the MTD. PALA improved the antitumour activity of CDDP or FdUrd when used alone; however, the highest tumour response, 66% complete tumour regression, was achieved with a PALA modulation of CDDP and FdUrd in combination.

Attenuation of the antitumor activity of 5-fluorouracil by (R)-5-fluoro-5,6-dihydrouracil

5-Ethynyluracil (5-EU; 776C85) is a potent mechanism-based inactivator of dihydropyrimidine dehydrogenase that improves the antitumor activity of 5-fluorouracil (5-FU) to a greater extent than can be accounted for by the improved 5-FU pharmacokinetics that result from preventing the catabolism of 5-FU. We therefore tested the effects of (R)-5-fluoro-5,6-dihydrouracil (5-FUH2), the 5-FU catabolite extensively formed in the absence of 5-EU, on the antitumor activity and toxicity of 5-FU in 5-EU-treated rats bearing large s.c. tumors. Rats were dosed once weekly for 3 weeks with the following regimens: 100 mg/kg 5-FU (maximum tolerated dose), 10 mg/kg 5-FU 1 h after 1 mg/kg 5-EU, or 10 mg/kg 5-FU plus 90 mg/kg 5-FUH2 1 h after 1 mg/kg 5-EU. The latter regimen was designed to approximate the exposure produced from 5-FU in the absence of 5-EU, where > 80% of the dose is catabolized. 5-FU produced complete and sustained tumor regressions in 94% of the animals pretreated with 5-EU. In contrast, 5-FU in combination with 5-FUH2 produced complete regression in only 38% of the 5-EU-treated rats, which was similar to the antitumor activity of 5-FU in the absence of 5-EU. All treatments resulted in 7-11% transient weight loss. 5-FU produced no other notable toxicity in 5-EU-treated rats. However, 5-FUH2 added to this regimen caused transient diarrhea and stomatitis in 13% of the animals, which was similar to the toxicity produced by 5-FU in the absence of 5-EU. Thus, 5-FUH2, or other downstream catabolites of 5-FU, impaired the antitumor activity and slightly increased the toxicity of 5-FU. Accordingly, 5-EU approved to improve the efficacy of 5-FU by preventing the formation of 5-FU catabolites.

Modulation of the antitumor-activity of 5-Fluorouracil and cisplatinum by N-phosphonacetyl-L-aspartate in the murine colon-carcinoma number-26

Modulation of the antitumor activity of cisplatinum (CDDP) alone or in combination with 5-fluorouracil (FUra) by N-phosphonacetyl-L-aspartate (PALA) was investigated in Balb/c mice bearing colon 26 adenocarcinoma, using weekly i.v. push schedule (days 1, 7 and 14) with PALA (100 mg/kg) been administered 24 h prior to each drug treatment. Antitumor activity was assessed at the maximum tolerated dose (MTD) of treatment by determining tumor doubling time (TD), ratio of tumor size in drug treated to control values (T/C) and by kinetic of tumor regression, being partial (PR) or complete (CR) tumor regression. In this model system, FUra and CDDP alone and in combination did not produce significant antitumor activity. Although tumor reduction by these agents was primarily in the form of PR, regrowth of tumor was apparent following termination of treatment. In contrast, pretreatment with a nontoxic dose of PALA produced significant increase in CR rates, ranged from 6% of treated animals with CDDP to 19% of animals treated with FUra. Furthermore, the greatest therapeutic efficacy was achieved when PALA was used to modulate the antitumor activity of the combination of FUra and CDDP. Under these conditions 70% and 30% of treated animals achieved PR and CR, respectively. With the weekly schedule use herein, PALA did not potentiate significantly the toxicity of either FUra or CDDP. Potentiation of CDDP toxicity by PALA was observed when the drug was used in combination with FUra, requiring approximately 6 fold reduction in CDDP dose. In brief, using the optimal doses of FUra and CDDP in combination, PALA potentiated significantly the antitumor activity of the combination in mice bearing a tumor relatively resistant to FUra and CDDP when used as a single agent and in combination.