Sodium succinate enhances the colorimetric reaction of the in vitro chemosensitivity test: MTT assay

We compared the colorimetric reactions between the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl 2H-tetrazolium bromide (MTT) assay and the succinate dehydrogenase inhibition (SDI) test, in order to evaluate the usefulness of the SDI test for in vitro chemosensitivity testing. The addition of sodium succinate enhanced the colorimetric absorbance at 565 nm in the MTT assay in a dose- and a time-dependent manner, in mouse sarcoma-180 (S-180) cells. At 10 microM of sodium succinate, a dose used in the SDI test, the absorbance of the MTT assay increased by about 2.5-fold in the S-180 cells and in 10 human tumor tissues. The absorbance in the SDI test correlated well with the viable cell number of S-180 cells (r = 0.9993). These results show that the SDI test, using MTT as a tetrazolium salt, has a higher sensitivity for predicting cell viability, compared to the MTT assay.

UFT is more antineoplastic against gastric carcinoma than 5-fluorouracil, 1-(2-tetrahydrofuryl)-5-fluorouracil and 1-hexylcarbamoyl-5-fluorouracil

The sensitivity of human gastric cancer tissue to 5-fluorouracil (5-FU) and its analogues 1-(2-tetrahydrofuryl)-5-fluorouracil (FT), UFT and 1-hexylcarbamoyl-5-fluorouracil (HCFU) was determined, using the in vivo subrenal capsule (SRC) assay. The relative variation of tumor size (delta TS/TS0) was calculated as follows: delta TS/TS0 = (TS6-TS0/TS0) x 100%, where TS6 was the tumor size on day 6 and TS0 on day 0. The chemosensitivity was considered to be positive when delta TS/TS0 in the treated group decreased to below -10%. For their cytotoxic effects, 5-FU analogues are converted to 5-FU and positive correlations were noted between the tumor sizes of 5-FU and its analogues (5-FU vs. FT, r = 0.737; 5-FU vs. UFT, r = 0.653; 5-FU vs. HCFU, r = 0.709), in gastric tissues from 22 patients. The means +/- SD of tumor size were -8.5 +/- 11.5% for 5-FU, -8.3 +/- 16.0% for FT, -18.1 +/- 15.8% for UFT and -13.7 +/- 13.4% for HCFU. Decrease in tumor size was marked in case of exposure to UFT, compared with that to 5-FU (p less than 0.001), FT (p less than 0.001) and HCFU (p less than 0.05). 18% were sensitive to UFT and resistant to 3 other drugs. Thus, UFT proved to be the most effective among 5-FU and its analogues for decreasing the size of gastric cancer tissues.

Colorectal carcinoma in vitro is more sensitive to 1-hexylcarbamoyl-5-fluorouracil compared with six other antitumor drugs: carboquone, Adriamycin, mitomycin C, aclacinomycin A, cisplatin, 5-fluorouracil

The sensitivity to 1-hexylcarbamoyl-5-fluorouracil (HCFU) of 25 colorectal cancer tissues was compared with that of six antitumor drugs: carboquone (CQ), Adriamycin (ADM), mitomycin C (MMC), aclacinomycin A (ACR), cisplatin (DDP), and 5-fluorouracil (5-FU), using the in vitro succinate dehydrogenase inhibition (SDI) test. Chemosensitivity was determined to be positive when the succinate dehydrogenase (SD) activity of the drug-exposed cells, at ten times the peak plasma concentration, was decreased to below 50 percent of that of control cells on day 3 of exposure. Decrease in SD activity was remarkable in cases of exposure to HCFU, compared with six other drugs. The sensitivity rates were 32 percent for CQ, 40 percent for ADM, 24 percent for MMC, 28 percent for ACR, 32 percent for DDP, 16 percent for 5-FU, and 68 percent for HCFU. The sensitivity rate for at least one of the six drugs (CQ, ADM, MMC, ACR, DDP, and 5-FU) was 52 percent, but was 80 percent when HCFU was taken into account. Since colorectal cancer tissues are resistant to various antitumor drugs, the chemosensitivity test of HCFU should aid in determining the effects of a particular drug for an individual patient.

1-Hexylcarbamoyl-5-fluorouracil is more cytostatic than 5-fluorouracil against human tumors in vitro

The sensitivity of HeLa cells and 15 human tumors, including eight gastric cancers, five colorectal cancers and two lung cancers to 1-hexylcarbamoyl-5-fluorouracil (HCFU) was compared with that to 5-fluorouracil (5-FU) in vitro. HeLa cells were doubly sensitive to HCFU, as compared to 5-FU. After the HeLa cells had been treated with 5-FU or HCFU at 77 microM for 1-5 h, the intracellular levels of 5-FU and HCFU were determined, using gas chromatographic-mass spectrometric methods. The level of HCFU plus 5-FU in the HCFU-treated cells was twice as high as the level of 5-FU in the 5-FU-treated cells. The sensitivity to HCFU in 15 tumor tissues varied with the tissue; however, all tissues tested were more sensitive to HCFU than to 5-FU, assessed using the succinate dehydrogenase inhibition test. These results suggest that the hexylcarbamoyl structure facilitates the rapid uptake of HCFU through the cell membrane. HCFU may prove to be more effective for treating each individual patient with a malignant lesion.

Structure and expression of human thrombomodulin, a thrombin receptor on endothelium acting as a cofactor for protein C activation

We have deduced the entire 575-amino acid sequence of the human thrombomodulin precursor from cDNA clones. The precursor starts with an 18-residue signal peptide domain, followed by the NH2-terminal domain, a domain with six epidermal growth factor-like structures, an O-glycosylation site-rich domain, a 24-residue transmembrane domain and a cytoplasmic domain. Simian COS cells transfected with the expression vector pSV2 containing thrombomodulin cDNA synthesized immunoreactive and functionally active thrombomodulin.

Poorly differentiated human gastric carcinoma is more sensitive to antitumor drugs than is well differentiated carcinoma

The chemosensitivities of 41 poorly differentiated gastric cancer tissues were compared with that of 16 well differentiated tissues, using the in vitro succinate dehydrogenase inhibition test. These human tissues obtained at the time of surgery were exposed to six different antitumor drugs: carboquone (CQ), adriamycin (ADM), mitomycin C (MMC), aclacinomycin A (ACR), cisplatin (DDP) and 5-fluorouracil (5-FU). The chemosensitivity was determined as positive when the succinate dehydrogenase (SD) activity of the drug exposed cells was decreased to below 50% of that of control cells, on day 3 of exposure. Decrease in SD activity was remarkable in the poorly differentiated tissues, compared to the well differentiated tissues, exposed to ADM, MMC, DDP and 5-FU. The sensitive rates were higher in the poorly differentiated tissues than in the well differentiated tissues, against all six antitumor drugs. Sixty-three per cent of the poorly differentiated tissues were sensitive to more than three antitumor drugs, in an identical tissue, but the rate was only 19% in the well differentiated tissues. The resistant rates to all drugs tested were 20% in the poorly differentiated and 31% in the well differentiated tissues. This would indicate that patients with a poorly differentiated gastric cancer will probably show a better response to antitumor drugs, compared to those with a well differentiated type.

[Chemosensitivity testing for 5-FU and 5-FU derivatives using subrenal capsule assay]

An evaluation was made, using in vivo subrenal capsule (SRC) assay, of the chemosensitivity of 12 human neoplastic tissues including 7 gastric cancers, 2 colo-rectal cancers, 2 lung cancers and 1 breast cancer, exposed to 5-fluorouracil (5-FU) and the 5-FU derivatives: tegafur (FT), UFT and hexylcarbamoyl-5-FU (HCFU). The relative variation of tumor size (delta TS/TS0) was calculated as follows: delta TS/TS0 = (TS6-TS0)/TS0 X 100 (%), where TS6 was the tumor size on day 6 and TS0 that on day 0, and more than a 10% decrease of delta TS/TS0 in the treated group was considered as positive for chemosensitivity. Delta TS/TS0 was decreased to -10.9 +/- 11.3% (mean +/- standard deviation) for 5-FU, -13.0 +/- 16.4% for FT, -19.8 +/- 18.2% for UFT and -18.8 +/- 15.1% for HCFU, and the inhibition of tumor growth following exposure to 5-FU correlated well with that following exposure to 5-FU derivatives (5-FU vs. FT, r = 0.659; 5-FU vs. UFT, r = 0.864; 5-FU vs. HCFU, r = 0.729). However, the sensitivity of each tumor varied; for example, the chemosensitivity was positive for 5-FU derivatives, but negative for 5-FU, in some tissues. The SRC assay appears to be useful for selecting sensitive drugs from 5-FU and 5-FU derivatives for individual cancer patients.

[Comparison between the succinate dehydrogenase inhibition test and ATP assay for in vitro chemosensitivity testing]

The predicted level of cell viability was compared between the succinate dehydrogenase inhibition (SDI) test and the adenosine triphosphate (ATP) assay, both of which are used for in vitro human tumor chemosensitivity testing. After HeLa cells had been exposed to various concentrations of 5-FU for 1, 2, 3 or 4 days, the decrease occurring in viable cell number correlated with that of succinate dehydrogenase (EC 1.3.99.1) activity and that of the intracellular ATP level of the viable cells. In dead cells, the ATP level was extensively decreased, but the succinate dehydrogenase activity remained at a level of 11% of that of 5-FU-untreated viable cells, even on day 4. The cell viability correlated well with the intracellular ATP level, as compared with the succinate dehydrogenase activity. The activity remaining in dead cells must thus be taken into consideration for the prediction of chemosensitivity in the SDI test, but not in the ATP assay.

Carboquone alters the protein synthesis of Chinese hamster V79 cell

The effect of carboquone (CQ) on protein synthesis in Chinese hamster V79 cells was determined. While the syntheses of higher molecular weight proteins decreased, the relative level of a 43-kilodalton (kd) protein increased following exposure to CQ at the concentration of 0.5 microgram/ml, in a time-related fashion, determined using one-dimensional gel electrophoresis. Using two-dimensional gel electrophoresis, the 43-kd protein may be actin protein, and the syntheses of another two proteins of 8.5/45 and 4.8/270 (designated isoelectric point/molecular weight, kd) were increased in the CQ-treated V79 cells. These changes of the proteins induced by CQ in V79 cells were noted in HeLa cells. Three CQ-induced proteins are candidates for the elucidation of the antineoplastic effect of CQ.

Comparison between succinate dehydrogenase inhibition test and subrenal capsule assay for chemosensitivity testing

The chemosensitivity result of the succinate dehydrogenase inhibition (SDI) test was compared with that of the subrenal capsule (SRC) assay in 23 human tumor tissues exposed to adriamycin (ADM), mitomycin C (MMC), cisplatin (DDP) and 5-fluorouracil (5-FU). The chemosensitivity was considered as positive when the succinate dehydrogenase (SD) activity of the drug-exposed cells was decreased to below 50% of that of control cells on day 3 in the SDI test, and the tumor size on day 6 was decreased to below -10% of that on day 0 in the SRC assay. Correlation rates between the decrease of SD activity in the SDI test and the decrease of tumor size in the SRC assay, using 23 evaluable cases in both assays, were r = 0.717 for ADM, r = 0.699 for MMC, r = 0.796 for DDP and r = 0.735 for 5-FU. The correlations of the chemosensitivity results were 73.9% for ADM, 73.9% for MMC, 82.6% for DDP and 60.9% for 5-FU. A positive correlation was noted between the in vitro and in vivo chemosensitivity results. This SDI test can serve as an effective tool for chemosensitivity testing.

[In vitro chemosensitivity of various human tumors evaluated by the succinate dehydrogenase inhibition (SDI) test (2)]

In vitro chemosensitivity was evaluated by succinate dehydrogenase inhibition (SDI) test in 94 human tumors including 59 gastric cancers, 27 colo-rectal cancers and 8 malignant lymphomas. Tumor fragments were exposed to 12 kinds of antitumor drugs at ten times peak plasma concentration. Evaluable rates were 86/94 (91%) for all cases, 56/59 (95%) for gastric cancers, 22/27 (81%) for colo-rectal cancers and 8/8 (100%) for malignant lymphomas. The mean of SD activity was decreased to 48% of that of control cells with aclacinomycin, 49% with carboquone, 53% with actinomycin D, 54% with mitomycin C and 54% with daunomycin for gastric cancers, 59% with adriamycin for colo-rectal cancers and 33% with cyclophosphamide (40487 S), and 33% with actinomycin D, 37% with vinblastine and 39% with adriamycin for malignant lymphomas. When the SD activity was reduced to below 50% by antitumor drugs, the chemosensitivity was defined as positive. The antitumor drugs which had a higher chemosensitive-positive rate were aclacinomycin, carboquone and mitomycin C for gastric cancers, adriamycin for colo-rectal cancers and 40487 S, daunomycin and vinblastine for malignant lymphomas. Our results suggest that the origin of a tumor is a critical factor in its chemosensitivity.

Isolation and characterization of thrombomodulin from bovine lung

Bovine thrombomodulin was isolated from the lung by Triton X extraction, affinity chromatography on diisopropyl phosphate-thrombin-agarose, and gel filtration on Ultrogel AcA-44. The final preparation was purified 6000-fold from the membrane extract with a yield of 21%. It showed apparent Mr of 78,000 and 105,000, before and after reduction, respectively, on polyacrylamide gel electrophoresis in SDS. The activity of the thrombomodulin was stable under the conditions of 1% SDS, 8 M urea, pH 2 and 10, and heat treatment at 60 degrees C for 30 min, but was unstable against treatment with 2-mercaptoethanol. Activation of protein C by thrombin in the presence of the thrombomodulin depended on Ca2+, and an equimolar complex formation between thrombin and thrombomodulin was required for the maximum rate activation. The rate of protein C activation by thrombin was increased 900-fold by thrombomodulin. Thrombomodulin inhibited the thrombin-induced fibrinogen clotting and platelet activation. However, it did not affect the inhibition of thrombin by antithrombin III with or without heparin, a protein C inhibitor or several synthetic inhibitors. These properties of bovine thrombomodulin were similar to those of rabbit thrombomodulin reported earlier.

Monoclonal antibodies to human protein C: effects on the biological activity of activated protein C and the thrombin-catalyzed activation of protein C1

Thirteen monoclonal antibodies designated as MFC-1 to MFC-13 were obtained from hybridoma cells cloned after the fusion of mouse myeloma cells with spleen cells of mice immunized with purified human protein C. Studies were made to determine where the antibodies bound to the molecule of protein C and whether they affected the biological actions of protein C. By using the immunoblotting technique, six of these antibodies were shown to bind to the light chain of protein C, and five to the heavy chain of protein C and also activated protein C. The remaining two antibodies bound to neither the light chain nor the heavy chain, though both antibodies bound to the intact protein C. Antibodies specific for the light chain did not bind to the gamma-carboxyglutamic acid-domain. Two of the antibodies specific for the heavy chain (MFC-13 and -1) inhibited the amidolytic activity of activated protein C. The MFC-13 also inhibited the activity of bovine activated protein C, but not that of human Factor IXa, Factor Xa, or thrombin. In addition to these two antibodies, another one for the heavy chain (MFC-10) and two antibodies for the light chain (MFC-9 and -11) inhibited the inactivation of Factor Va by human activated protein C. One of the antibodies which inhibited the enzyme activity (MFC-1) blocked the inhibition of activated protein C by protein C inhibitor. Another one for the heavy chain (MFC-5) inhibited the activation of protein C by thrombin regardless of the presence or absence of thrombomodulin. Based on these results, we have established the positions of some monoclonal antibody-binding sites on the protein C molecule.

Mechanism of inhibition of activated protein C by protein C inhibitor

Protein C inhibitor isolated from human plasma inhibited thrombin, factor Xa, trypsin and chymotrypsin as well as activated protein C, but had very little effect on urokinase and plasmin. The inhibition constants (K1) of protein C inhibitor for activated protein C, thrombin and factor Xa were 5.6 X 10(-8) M, 6.7 X 10(-8) M and 3.1 X 10(-7) M, respectively. The second-order rate constant for inhibition of activated protein C by the inhibitor increased about 30-fold in the presence of an optimal heparin concentration (5-10 units/ml). The inhibition of activated protein C by plasma protein C inhibitor was also accelerated by heparin. When activated protein C (Mr = 62,000) was incubated with protein C inhibitor (Mr = 57,000), enzyme-inhibitor complexes with apparent Mr = 102,000 and 88,000 were observed in the nonreduced and the reduced samples, respectively, on SDS-polyacrylamide gel electrophoresis. In addition to these complexes, a band of unbound enzyme and a band with Mr = 54,000 were detected. When 125I-labeled protein C inhibitor was exposed to activated protein C, the inhibitor band was converted to bands with apparent Mr = 102,000 and 54,000 in the nonreduced samples, as determined by autoradiography after gel electrophoresis in SDS. The band with Mr = 54,000 also appeared when the inhibitor reacted with other serine proteases. The activated protein C was released from the inactive complex by treatment with 1 M ammonia or hydroxylamine. This phenomenon was found by SDS-polyacrylamide gel electrophoresis to represent the dissociation of the enzyme-inhibitor complex by ammonia or hydroxylamine into the free enzyme and the proteolytically modified inhibitor.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative double-blind trial of dl-alpha-tocopheryl nicotinate on vibration disease

Sixty inpatients with vibration disease were examined on the effect of dl-alpha-tocopheryl nicotinate by comparative double-blind study. The observed period was 6 weeks and the dose was 6 capsules a day (600 mg as dl-alpha-tocopheryl nicotinate, Juvela Nicotinate, referred to as EN). The physical exercise therapy was applied to all patients throughout the test period. EN group became better with a significant difference from P (placebo) group in the subjective symptoms, the clinical examinations and the collective improving rate (p less than 0.01, 0.05, 0.01), respectively. The improvement of the subjective symptoms of both groups was higher 6 weeks than 3 weeks after administration. Most items in EN group became better significantly (p less than 0.05) as compared with those in P group. The examinations of the peripheral functions in EN group showed a significant improvement 6 weeks after administration in comparison with those in P group. Blood chemistry, blood cell counts and serum electrolytes changed within normal range. Thus, this preparation would be a curative agent for patients with vibration disease.

Digital plethysmographic responses to auditory stimuli in patients with vibration disease

Digital plethysmographic responses to auditory stimuli in 15 healthy men and 82 patients with vibration disease were analyzed in order to clarify the functional conditions of autonomic nervous system in this disease. The auditory stimuli given to healthy men caused a rapid decrease in the amplitude of the plethysmograms. After cessation of the auditory stimuli the decreased amplitude recovered to the control value within 30 sec. In the patients with vibration disease, however, the recovery of the decreased amplitude was delayed. The plethysmographic changes in the patients with vibration disease were divided into 4 types: normal (N), intermediate (I), delayed (D) and poor response (P) types. Each type of I, D and P was altered to type N by treatments consisting of therapeutic exercises, hot spring cures and so on. All healthy men showed type N. There were no significant differences between the time courses of the recovery of the plethysmographic changes and the amplitudes of the plethysmograms before the auditory stimuli. The results obtained seem to indicate that the autonomic nervous system in the patient with vibration disease is in disorder, and that the digital plethysmography with auditory stimuli is instrumental to detect the functional changes in the autonomic nervous system.