[The effect of epidural saline injection on analgesic level during combined spinal and epidural anesthesia]

The purpose of this study is to clarify the volume effect of epidural saline injection 20 min after spinal anesthesia. Thirty patients undergoing combined spinal and epidural anesthesia for orthopedic surgery were randomly divided into two groups: a control group (n = 15) and a saline group (n = 15). In the control group, 2% lidocaine 3 ml with 0.4% tetracaine was injected into the subarachnoid space from L 4-5 interspace using Durasafe (Becton Dickinson, USA) and saline was not injected into the epidural space. In the saline group, saline 10 ml was injected through an epidural catheter 20 min after spinal anesthesia. The levels of analgesia 20 min after spinal anesthesia were not significantly different between the groups. However, the levels of analgesia 3, 5, 10, 40 and 100 min after epidural saline injection in the saline group were significantly higher than those in the control group (P < 0.05). The highest analgesic level was obtained 10 min after epidural saline injection and reached to T 4.3 +/- 1.1. In conclusion, epidural saline injection increases the analgesic level 20 min after spinal anesthesia because of the volume effect.

Interferons alpha-2a and beta increase the antitumor activity, detected by MTT assay, of 5-fluorouracil against experimental and clinical human gastrointestinal carcinomas

In order to investigate the combined antitumor activity of 5-fluorouracil (5-FU), and recombinant human interferon alpha 2a (IFN alpha) or human fibroblastoid interferon beta (IFN beta), the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide (MTT) assay was carried out using a cultured human colon cancer cell line (C-1) and fresh surgical specimens of gastric and colon carcinomas. IFNs did not show positive antitumor activity against C-1 cells, whereas 5-FU showed time- and concentration-dependent antitumor activity against C-1 cells. Furthermore, the antitumor activity of 5-FU on C-1 cells was augmented by IFN alpha or beta. When 5-FU (50 micrograms/ml) with IFN alpha (50 IU/ml). or IFN beta (50 IU/ml) was applied for the MTT assay with 48 hours incubation of fresh surgical specimens of gastric and colon carcinomas, the inhibition rates increased by 10% in 9 of 21 gastric specimens and in 18 of 36 colon carcinomas for IFN alpha (47.4% or 27/57), and in 8 of 15 gastric specimens and in 15 of 28 colon carcinomas for IFN beta (53.5% or 23/43). These results suggest that the chemosensitivity to 5-FU of human gastric and colon carcinomas is increased in the presence of IFNs, without involvement of the host-mediated immune system, and that this combined effect can be predicted by the MTT assay in vitro.

The modulating effect of interferon alpha-2a on the antitumor activity of UFT against a human gastric carcinoma xenograft, SC-1-NU, in nude mice

The modulating effect of recombinant human interferon alpha-2a (IFN) on the antitumor activity of UFT, a mixed compound of tegafur and uracil at a molar ratio of 1:4, was investigated against SC-1-NU, a human gastric cancer xenograft serially transplanted in nude mice. IFN was administered subcutaneously at a dose of 60,000 IU/mouse daily for 14 days, and UFT was given at a dose of 15 mg/kg as tegafur daily, except on Sundays, for 3 weeks. The agents were administered either alone or simultaneously. Synergistic antitumor activity on SC-1-NU was produced by the combination of IFN and UFT without any increment of side effects, and the combination therapy also increased intratumoral thymidylate synthetase (TS) inhibition and the amount of 5-fluorouracil (5-FU) in the intratumoral RNA. Thus, IFN seems to modulate the antitumor activity of UFT against SC-1-NU through an inhibition of DNA synthesis and RNA distortion, and therefore this combination could be useful for clinical application.

Dual modulation by l-leucovorin and recombinant human interferon alpha 2a of 5-fluorouracil antitumor activity against the human colon carcinoma xenograft Co-4

We investigated the dual modulation by l-leucovorin (LV) and recombinant human interferon-alpha 2a (IFN-alpha 2a) of 5-fluorouracil (5-FU) antitumor activity against human colon carcinoma cells (Co-4) using a nude mouse system. 5-FU was administered intraperitoneally (IP) at 10 or 90 mg/kg. 5-FU (10 mg/kg) was administered daily for 10 days, and 90 mg/kg was administered once. LV was administered IP 1 and 0 h before 5-FU treatment at 200 mg/kg. IFN-alpha 2a was administered subcutaneously (SC) daily for 14 days at 60,000 IU/mouse. When 5-FU was administered at 10 or 90 mg/kg with these two modulators, the antitumor effect was increased significantly, with T/C ratios of 18.1 and 6.1, respectively. These modulatory effects were assessed as synergistic, without associated severe side effects or death during the experimental period. LV augmented the antitumor activity of 5-FU through increment of thymidylate synthetase (TS) inhibition, and IFN-alpha 2a showed a modulatory effect in elevating the intratumoral concentration of fluorouridine without change in TS inhibition. These results suggest that 5-FU antitumor activity against human colon carcinoma could be significantly potentiated without severe side effects by these two modulators, which possess different modes of action.

In vivo antitumor activity of hexamethylmelamine against human breast, stomach and colon carcinoma xenografts

We have evaluated the antitumor activity of Altretamine (hexamethylmelamine, HMM) on human carcinoma xenografts serially transplanted in nude mice. Five human breast carcinoma xenografts, MX-1, T-61, MCF-7, R-27 and Br-10, were inoculated subcutaneously into female nude mice. Two human stomach carcinoma xenografts, SC-1-NU and St-4, and three human colon carcinoma xenografts, Co-3, Co-4 and Co-6, were inoculated subcutaneously into male nude mice. One pellet of 17 beta-estradiol (0.1 mg/mouse) was inoculated subcutaneously in the mice transplanted with MCF-7 when the tumors were inoculated. HMM was administered per os daily for 4 weeks. MX-1 and T-61 tumors regressed completely after treatment with HMM at a dose of 75 mg/kg (the maximum tolerated dose: MTD) for MX-1 and 25 mg/kg for T-61. Br-10 was sensitive, whereas MCF-7 and R-27 were resistant to HMM at its MTD. HMM exerted the most potent antitumor effect against T-61. Against MX-1, it exerted an antitumor effect equivalent to that of cisplatin or cyclophosphamide. In addition, this agent was effective against all stomach and colon carcinoma xenografts, in particular St-4 (T/C% = 10.7: the mean tumor weight of treated group/the mean tumor weight of control group) and Co-3 (T/C% = 31.5%) which are insensitive to presently available agents. HMM seems worthy of further clinical investigation as a candidate agent to treat breast, stomach, colon and other carcinomas.

Recombinant human interferon alpha-2a increases the antitumor activity of 5-fluorouracil on human colon carcinoma xenograft Co-4 without any change in 5-FU pharmacokinetics

We investigated the modulating effect of recombinant human interferon alpha-2a (IFN-alpha) on the antitumor activity of 5-fluorouracil (5-FU) against a human colon carcinoma xenograft (Co-4) in nude mice with reference to changes in the pharmacokinetic pattern of 5-FU. Mice bearing Co-4 received 5-FU ip at a dose of 90 mg/kg once with or without IFN-alpha, which was administered sc at a dose of 60.000 IU/mouse daily for 7 days before 5-FU treatment. When the area under the curve (AUC) and peak plasma concentration (Cmax) of 5-FU with or without IFN-alpha were measured as pharmacokinetic parameters, the pharmacokinetics of 5-FU was not changed by IFN-alpha administration. This result suggests that the modulating effect of IFN-alpha on 5-FU does not involve augmentation of 5-FU pharmacokinetic parameters.

Synergistic antitumor activity of combination chemotherapy with mitomycin C and cisplatin against human gastric cancer xenografts in nude mice

A new combined cancer chemotherapy regimen of mitomycin C (MMC) and cisplatin (DDP) showed synergistic antitumor activity against human gastric cancer xenografts St-40 and SC-1-NU in BALB/c nu/nu mice. The drugs were administered intraperitoneally at doses of 2 or 4 mg/kg for MMC and 3 or 6 mg/kg for DDP, respectively. To clarify the schedule-dependent antitumor activity of MMC and DDP against St-40 and SC-1-NU, different sequential therapies were conducted. Simultaneous administration of these agents showed the highest antitumor activity against SC1-NU among the three regimens used, whereas the sequence of MMC followed by DDP showed higher antitumor activity than the reverse sequence against St-40. The intratumoral concentration of platinum was significantly increased in St-40 treated with the sequence MMC to DDP, in comparison with the sequence DDP to MMC. The maximum tolerated dose (MTD) of this combination was 4 mg MMC plus 6 mg DDP per kg in all the combinations, and these MTDs were 2/3 of the corresponding values for their single use. Since this combination increased the antitumor activity of each single agent without any increase in their toxicity, it would appear to be useful clinically.

[A case report of left limb compartment syndrome associated with laparoscopic surgery]

A 63-year-old male patient with early gastric cancer was attempted for laparoscopic wedge resection of the stomach. After the introduction of anesthesia, bandage of bilateral leg was carried out to prevent deep venous thrombosis during laparoscopic surgery. Although the procedure was converted to open surgery, the bandage has been continued throughout the surgery for 6 hours. After the operation, the swelling and severe tenderness at his left leg was observed. MRI revealed remarkable edema in left deep posterior compartment. Under diagnosis of left limb compartment syndrome, fasciotomy was carried out. Postoperatively the patient did well without any functional disturbance.

Recombinant human interferon alpha-2a increases 5-fluorouracil efficacy by elevating fluorouridine concentration in tumor tissue

The modulating effect of recombinant human interferon alpha (IFN-alpha) on the antitumor efficacy of 5-fluorouracil (5-FU) against human carcinoma cell lines was investigated in vitro and in vivo. 5-FU, fluorouridine (FUR) or fluoro-5'-deoxyuridine (FUdR) were tested against cultured human colon tumor C-1 cells with or without IFN-alpha. The in vitro antitumor activity of 5-FU was enhanced by the addition of IFN-alpha, but IFN-alpha did not increase the effect of FUR or FUdR. The in vivo antitumor activity of 5-FU with or without IFN-alpha was assessed using Co-4, a human colon carcinoma xenograft, in nude mice. Thymidylate synthetase inhibition and concentration of FUR in the treated tumor tissues were concomitantly measured. A synergistic effect of 5-FU and IFN-alpha was observed on Co-4 in nude mice, and this in vivo synergism was obtained without any increment of thymidylate synthetase inhibition or side effects in terms of death rate and body weight loss. The intratumoral concentration of FUR was significantly increased by the addition of IFN-alpha in Co-4 tumor tissue treated with 5-FU. These results suggest that the mechanism of the combined effect of 5-FU and IFN-alpha is not related to enhancement of thymidylate synthetase inhibition, but to an increase of FUR concentration in the target tumor tissue. It is expected that this combination method will be clinically useful for the treatment of advanced colorectal carcinoma.

Antitumor activity of (2''R)-4'-O-tetrahydropyranyl adriamycin on human gastric cancer cell lines in vitro and in vivo

The antitumor activity of (2''R)-4'-O-tetrahydropyranyl adriamycin (pirarubicin; THP) was assessed using human gastric cancer cell lines in vitro and in vivo. The cytotoxicity of THP on MKN-28 and MKN-45 was superior to that of adriamycin (ADM) as detected by a growth assay with an MTT colorimetric endpoint. When the same doses of THP and ADM were administered intraperitoneally to nude mice bearing St-15, St-40 and SC-1-NU, the antitumor activity of THP was almost equivalent to ADM in terms of relative mean tumor weight. However, the adverse effects of THP were also significantly lower than those of ADM in terms of death rate, body weight loss and spleen weight loss. This was also confirmed in THP or ADM combination chemotherapy with mitomycin C and 5-fluorouracil on St-15 and MKN-45. These results indicated that THP is a candidate anthracycline to replace ADM for combination cancer chemotherapy in gastric carcinoma.

Combined effect of 5-fluorouracil and carboplatin against human gastric cancer cell lines in vitro and in vivo

The antitumor activity of a sequential combination of 5-fluorouracil (5-FU) and carboplatin (JM-8) was evaluated using gastric cancer cell lines in vitro and in vivo. In the in vitro study, the sequence of 5-FU followed by JM-8 showed higher antitumor activity than that of the reverse sequence. The sequence of 5-FU at 5 micrograms/ml for 24 h followed by 5 micrograms/ml JM-8 for 24 h showed antitumor activity almost equivalent to that of 10 micrograms/ml 5-FU for 24 h and higher activity than that of 10 micrograms/ml JM-8 for 24 h on two cell lines. To evaluate the antitumor activity and toxicity of 5-FU and JM-8 in vivo, BALB/cA nu/nu mice bearing human gastric cancer xenografts St-15, St-40 and SC-1-NU were administered 5-FU and JM-8 intraperitoneally. The sequence of 5-FU prior to JM-8 showed higher antitumor activity than that of the reverse sequence on all the xenografts, and simultaneous administration of 5-FU and JM-8 showed the most potent antitumor activity on St-40 and SC-1-NU. On the other hand, the sequence of 5-FU before JM-8 showed the lowest toxicity in all the treated groups, in terms of death rate, body weight loss and spleen weight loss. This combination is thought to be a promising chemotherapy regimen, showing high antitumor activity without an increment of toxicity.

Splenic abscess associated with colon cancer: a case report

The present report describes a case of colon cancer which presented with a rare complication of splenic abscess. A 52-year-old Japanese man with diarrhea, fever and chills was admitted to our hospital. He complained of fever, with chills at night, and abdominal pain occurring during the last month. The origin of the fever was investigated, and Escherichia coli grew from a blood culture. Multilocular splenic abscesses and wall thickening of the descending colon were revealed by CT scan, magnetic resonance imaging and ultrasound. A cancer of the descending colon was found by barium enema and colonoscopy. A curative resection was performed and the pathological report revealed the splenic abscess to have developed from a direct extension of, and perforation by, the carcinoma of the descending colon.

Synergistic antitumor activity of mitomycin C and cisplatin against gastric cancer cells in vitro

The synergistic antitumor activity of mitomycin C (MMC) and cisplatin (DDP) against the gastric cancer cell lines MKN-28 and MKN-45 was assessed in vitro using the MTT assay. The synergism of the two agents was evaluated in terms of the interaction index (I.I.). The sequence of MMC followed by DDP showed higher antitumor activity than the reverse sequence against MKN-28 and MKN-45, and the intracellular concentration of platinum was significantly increased in MKN-45 by preincubation with MMC, suggesting that MMC modulates cellular permeability to DDP or the ability of DDP to intercalate DNA. Since these two antitumor agents show different types of toxicity clinically, i.e., myelotoxicity by MMC and nephrotoxicity by DDP, this combination chemotherapy could be advantageous by providing synergistic antitumor activity without increased toxicity.

Different chemo- and endocrino-sensitivity of MCF-7 cells with or without estradiol supplement in vitro

The sensitivity of MCF-7 cells to tamoxifen (TAM) and mitomycin C (MMC) was assessed in rapidly and slowly growing cells with or without estradiol supplementation, respectively. The growth of MCF-7 was inhibited by MMC in a concentration-dependent manner with or without estradiol (E2) supplementation. Preincubation with MMC suppressed subsequent E2 stimulated growth of MCF-7. TAM inhibited the growth of MCF-7 supplemented with E2 and preincubation with TAM prevented subsequent E2 stimulated growth of MCF-7. However, TAM did not inhibit the growth of MCF-7 cells in E2 free medium. These results suggested that MMC may be more effective than TAM on breast cancer cells in the dormant or slow-growth phase.

The modulation by L-leucovorin of 5-fluorouracil antitumor activity on human colon carcinoma cells in vitro and in vivo

We investigated the modulating effect of L-leucovorin (LV) on the antitumor effect of 5-fluorouracil (5-FU) against human colon carcinoma cells (C-1) in vitro and human colon carcinoma xenografts (Co-4) in nude mice. The modulating effect of LV on 5-FU reached an optimal concentration of 40-80 micrograms/ml in vitro which was detected by a colorimetric MTT assay. An optimal dose of 200 mg/kg was also observed in the nude mouse system. The modulating effect of LV increased according to the increment of thymidylate synthetase inhibition in vivo. Since the pharmacokinetic pattern of LV in the nude mice administered LV at 200 mg/kg was similar to that in patients treated with LV at a dose of 100 mg/m2, this clinical method of administration was thought to be adequate for modulating the antitumor activity of 5-FU against clinical colon carcinomas.

A metastatic model of human colon cancer constructed using cecal implantation of cancer tissue in nude mice

COL-2-JCK, a human colon cancer xenograft line able to be transplanted into nude mice, was implanted in the subserosal layer of the cecum, either as cancer tissue or as a single cell suspension. When cancer tissue was used for the cecal implantation, 100% extensive local tumor growth and a high incidence of metastases to the regional lymph nodes, peritoneum, liver, and lung was observed. In contrast, when the cell suspension of this line was injected into the cecal wall, no metastases were observed, with significantly reduced local tumor growth. The use of cancer tissue maintaining the original cancer tissue structure is therefore considered imperative for allowing full expression of the biological characteristics of cancer cells. This nude mouse model using the cecal implantation of cancer tissue should thus prompt further study on the biology of human colon cancer.

A newly developed hexamethylmelamine derivative, SAE9 with both antitumor and aromatase-inhibitory activity

Hexamethylmelamine (HMM) has previously been shown to be active against ovarian, breast and small cell lung cancer. However HMM dose not have aromatase-inhibitory activity. A newly developed HMM derivative, 2-N,N-dimethylamino-4, 6-bis (1-H-imidazol-1-yl)-1,3,5-triazine (SAE9), was found to have direct antitumor activity as well as aromatase-inhibitory activity. The direct antitumor activity on breast carcinoma cell lines (MCF-7, R-27 and MDA-MB-231) was assessed using the 3-(4,5-dimethylthiazol-2yl)-2, 5-diphenyl tetrazolium bromide (MTT) on cells growing in monolayer culture. The 50% inhibitory concentrations (IC50) of SAE9 were found to be approximately 10(-4) M for each cell line, roughly equivalent to those of HMM. When the aromatase-inhibitory effect was assessed using a human placental aromatase-inhibitory assay, the IC50 of SAE9 was 5.5 x 10(-7) M, which was superior to that of aminoglutethimide (AG) (3.8 x 10(-5) M). In a rat uterine growth model treated with androstenedione as the in vivo aromatase inhibition assay, SAE9 had an effect equivalent to that of AG. Since SAE9 has both antitumor and aromatase-inhibitory activity on breast carcinoma cell lines with estrogen dependency, this and similar non-steroidal aromatase inhibitors are thought to be promising for further study.

Site-specific chemosensitivity of human small-cell lung carcinoma growing orthotopically compared to subcutaneously in SCID mice: the importance of orthotopic models to obtain relevant drug evaluation data

We have developed a novel in vivo model of human small-cell lung carcinoma (SCLC) using orthotopic reconstitution by injecting human SCLC in the tail vein of severe combined immunodeficient (SCID) mice whereby the SCLC grows in the lung and other organs. Cisplatin (DDP) had significant antitumor effects on the SCLC growing orthotopically in the lung whereas mitomycin C (MMC) did not, thereby reflecting the clinical situation. However, the opposite effects were found when the SCLC was growing subcutaneously, where the tumors responded to MMC and not to DDP. This suggests that the tumors growing orthotopically reflect the clinical effects of drugs on human SCLC more closely than the tumors growing subcutaneously. Therefore, this orthotopic reconstitution model of human SCLC in SCID mice is thought to be useful for studies on the treatment of human SCLC and emphasizes the need for orthotopic models for relevant cancer drug evaluation.

Significance of in vitro attachment of human colon cancers to extracellular matrix proteins in experimental and clinical liver metastases

The attachment of 7 human colon cancer lines transplantable into nude mice, and primary tumors and liver metastases from 30 patients with colon cancer to 4 extracellular matrix proteins (EMPs)--Matrigel, laminin, fibronectin, and type IV collagen--was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H (MTT) assay. Cancer cells from the 4 established tumor lines which produced experimental liver metastases in vivo showed significantly greater attachment to each EMP than those from the other 3 tumor lines which did not. Although there were no significant differences between attachment to EMPs of cancer cells from 15 clinical primary tumors with liver metastases and those without, attachment to each EMP of cells derived from liver metastases was significantly greater than that of the cells from the corresponding primary tumors in 8 cases for which liver metastases and primary tumors were examined simultaneously. Attachment to EMPs, which could be determined simply and rapidly using the MTT assay, is thus considered a significant factor in experimental and clinical liver metastases of human colon cancers.

Immunochemotherapy prevents human colon cancer metastasis after orthotopic onplantation of histologically-intact tumor tissue in nude mice

A metastatic model of human colon cancer has been previously established using orthotopic onplantation of histologically intact in tissue nude mice. In this study, effects of immunochemotherapy using OK-432, 5-fluorouracil (5-FU) and mitomycin C (MMC) on Col-2-JCK, a human colon cancer xenograft, were evaluated using this model. When 5-FU and MMC were administered without OK-432, liver metastases were not reduced even at maximum tolerated doses of both drugs, although cecal tumor growth was significantly reduced. On the other hand, when combined with OK-432, both 5-FU and MMC reduced liver metastases with synergistic reduction of cecal tumor growth, demonstrating the potential of combining immunotherapy with chemotherapy against metastases.

Interferon beta increases antitumor activity of 5-fluorouracil against human colon carcinoma cells in vitro and in vivo

The modulating effect of human fibroblast-derived interferon beta (IFN-beta) on the antitumor effect of 5-fluorouracil (5-FU) against human colon carcinoma cells in vitro and in vivo was investigated. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide (MTT) assay was carried out in vitro using the cultured human colon cancer cell line C-1. IFN-beta at concentrations of 50, 500, 5,000 and 50,000 IU/ml was added to the cultured tumor cells with or without 5-FU at concentrations of 10, 50 and 500 micrograms/ml. The antitumor activity of 5-FU with or without IFN-beta was assessed using Co-4, a human colon carcinoma xenograft in nude mice, with reference to thymidylate synthetase inhibition. IFN-beta was administered subcutaneously daily for 14 days at doses of 6,000, 60,000 and 600,000 IU/mouse. The combined antitumor effect with 5-FU was evaluated by simultaneous intraperitoneal administration of 5-FU at doses of 10 and 20 mg/kg daily for 10 days. The antitumor activity of IFN-beta alone increased in a dose-dependent manner against Co-4 in nude mice, whereas its antitumor activity in vitro against C-1 was limited. The synergistic effect of 5-FU and IFN-beta was observed both in vitro and in vivo, and the in vivo synergism was obtained without any enhancement of thymidylate synthetase inhibition or side effects in terms of death rate and body weight loss. These results suggest that the mechanism of the combined effect of 5-FU and IFN-beta is not related to enhancement of thymidylate synthetase inhibition or the host immune system, since human fibroblastoid IFN-beta is species-specific to humans. The clinical usefulness of this combination method for the treatment of advanced colorectal carcinoma is expected.

Colorimetric chemosensitivity testing using sulforhodamine B

A colorimetric chemosensitivity test was investigated using sulforhodamine B (SRB), which stains protein synthesized by cells, as an end-point marker. Four cultured cell lines, 9 human tumor xenografts serially transplanted into nude mice, and 14 fresh surgical specimens were subjected to this assay. The optimal conditions for the assay were 3-5 x 10(4) cells per well in a 96-microplate, an SRB concentration of 4%, and an incubation time of more than 10 minutes. When mitomycin C, doxorubicin, cisplatin, and 5-fluorouracil were assessed by the SRB assay, the concentration-effect curves revealed a sharp slope between plateaux at low and high concentrations, suggesting that this assay has an excellent sensitivity which can assess the effect of drugs as "all or none." Although this high sensitivity resulted in good reproducibility of the assay for cultured cell lines, the predictive rate of the SRB assay for the chemosensitivity of human tumor xenografts in vivo was limited to 63.9%. As a result, this SRB assay is thought to be useful for evaluating the chemosensitivity of cultured cells as all or none, since it can assess directly cellular protein synthesis, which is one of the most important parameters of cell renewal, with excellent sensitivity.

Experimental cancer chemotherapy using a liver metastatic model of human colon cancer transplanted into the spleen of severe combined immunodeficient mice

We have developed a liver metastatic model of human colon cancer using severe combined immunodeficient (SCID) mice. Liver metastases were observed in all the SCID mice on day 28 after intrasplenic injection with 5 x 10(6) dissociated tumor cells of COL-2-JCK, a human colon cancer strain serially transplanted in nude mice. When this model was applied for chemotherapeutic experiments, 5-fluorouracil (5-FU) demonstrated significant antitumor effects in preventing liver metastases, whereas the efficacy of 5-FU was limited in the currently used sc-ip chemosensitivity assay in nude mice. When the human LDH-5 isozyme was evaluated in the homogenized metastatic liver tissue of SCID mice, a good correlation was obtained between the liver tumor weights and LDH-5 isozyme, suggesting that it could be a promising quantitative indicator for metastases. This model would be useful for further studies on the treatment of liver metastases of colon cancer.

Growth of human tumor xenografts in nude mice and mice with severe combined immunodeficiency (SCID)

Twenty-three fresh tumor specimens obtained at surgery and 5 serially transferable human tumor xenografts were implanted subcutaneously into nude mice and mice with severe combined immunodeficiency (SCID) to compare the take rates of the fresh surgical specimens and the growth rates of the transferable strains. The overall take rates were 65% for the SCID mice and 60% for the nude mice, without any significant difference, although colon carcinoma seemed to have higher acceptance in the SCID mice with a take rate of 6/8. All the serially transferable strains were successfully accepted in the SCID mice, their growth rates being essentially identical to those in the nude mice. These results indicate that the SCID mouse can be used as a human tumor xenograft-mouse system as well as the nude mouse.