Protective effect of coenzyme Q10 on cultured skeletal muscle cell injury induced by continuous electric field stimulation

The protective effect of coenzyme Q10 (CoQ10) on continuous electric field stimulation-induced muscular injury was investigated in cultured cells established from neonatal rat femoral muscles. After cultivation for 9 days, skeletal muscle cells contracted and relaxed rhythmically for 4 hr in response to continuous electric field stimulation (power, 5 V; duration, 5 msec; amplitude, 3 Hz). After the onset of the stimulation, lactate and lactate dehydrogenase (LDH) release and intracellular Ca2+ contents ([Ca2+]i) at relaxation increased gradually. In contrast, the intracellular ATP contents decreased. The addition of 5 microM CoQ10, but not alpha-tocopherol and radical scavengers, to the culture medium protected the cells against these biochemical changes after the stimulation. Verapamil, an inhibitor of Ca2+ channels, also attenuated the increase in [Ca2+]i at relaxation and LDH. These results suggested that one of the causal mechanisms of muscular injury is an increase in [Ca2+]i due to the excess entry of extracellular Ca2+, and that CoQ10 can protect skeletal muscle cells against such undesirable biochemical changes.

Characterization of a novel parathyroid hormone (PTH) receptor with specificity for the carboxyl-terminal region of PTH-(1-84)

Carboxyl-terminal fragments of PTH (C-PTH) appear to have biological properties different from those mediated by the amino-terminal portions of PTH and PTH-related peptide (PTHrP). To characterize a C-PTH receptor that may be involved in mediating these functions, we performed RRAs and affinity cross-linking studies with several clonal cell lines. Radiolabeled recombinant [Leu8,18,Tyr34]human PTH-(1-84)[mutPTH-(1-84) and [Tyr34] human PTH-(19-84)[mutPTH-(19-84) showed little or no specific binding to stably expressed recombinant PTH/PTHrP receptors. However, high affinity binding was observed using osteoblast-like and rat parathyroid (PT-r3) cells. The apparent Kd values were 20-30 nM for PTH-(1-84), mutPTH-(1-84), and mutPTH-(19-84), respectively; 400-800 nM for PTH-(39-84); and more than 5000 nM for PTH-(53-84). [Nle8,18,Tyr34]bovine PTH-(1-34)amide [PTH-(1-34)], PTH-(44-68), PTHrP-(37-74), and PTHrP-(109-141) showed no displacement of either radioligand. C-PTH receptor number was increased up to 2-fold by pretreating ROS 17/2.8 cells with increasing doses of PTH-(1-34), PTH-(1-84), or 8-bromo-cAMP, whereas no change was observed in response to dexamethasone or PTH-(39-84). Cross-linking studies using radiolabeled mutPTH-(1-84) or mutPTH-(19-84) revealed specific labeling of two proteins in ROS 17/2.8 cells that were approximately 40 and 90 kilodaltons in size (including the radioligand of approximately 10 kilodaltons). The intensity of affinity labeling of both proteins was dose dependently inhibited by increasing concentrations of unlabeled PTH-(1-84) and several carboxyl-terminal PTH-(1-84) fragments, but not by PTH-(1-34). Similar studies with PT-r3 cells revealed only a single protein band of about 90 kilodaltons. These data indicate that the carboxyl-terminal portion of PTH-(1-84) binds specifically to a unique receptor/binding protein distinct from the previously isolated PTH/PTHrP receptor.

A comparison of biological effects of modulated carbon-ions and fast neutrons in human osteosarcoma cells

PURPOSE

To compare the biological effects of a 135 MeV/u carbon-ion beam and 13 MeV fast neutron beam using human osteosarcoma cells.

METHODS AND MATERIALS

We have studied the clonogenic cell survival, recovery of potentially lethal damage (PLD) in plateau phase cells, and spheroid cure in multicellular spheroid after irradiation at various positions in the plateau and spread out Bragg peak (SOBP) of a 135 MeV/u carbon-ion beam and with 13 MeV neutrons. The carbon beam had a 4-cm range in water and a range filter was used to produce a 3-cm extended-peak region. The reference radiation was 137Cs gamma-rays.

RESULTS

The relative biological effectiveness (RBE) values for 10% survival level of plateau phase cells for carbon-ions at the position of plateau, proximal peak, midpeak, and distal peak within the SOBP, and neutrons were 1.71, 2.48, 2.63, 3.47, and 2.29, respectively. Corresponding RBE values at 1% level were 1.64, 1.93, 2.06, 2.49, and 2.05. The extent of recovery from PLD was reduced after carbon-ions at proximal peak, midpeak, and distal peak, and neutrons, although not substantially reduced after carbon-ions at plateau. The RBE values for 50% spheroid cure level of spheroids for carbon-ions at the position of plateau, proximal peak, midproximal peak, middistal peak, and distal peak within the SOBP, and neutrons were 1.69, 1.88, 1.87, 1.94, 2.03, and 1.90, respectively.

CONCLUSIONS

The biological parameters measured all indicate an approximately comparable biological effectiveness between 75-80 KeV/microns carbon-ions of the SOBP and 13 MeV neutrons in the human tumor model studied in vitro.

Melittin cardiotoxicity in cultured mouse cardiac myocytes and its correlation with calcium overload

Venom from the honey bee Apis mellifera induces cardiovascular dysfunction. We studied which constituent(s) of the venom induces cardiotoxicity and how, using cultured cardiac myocytes from mouse fetuses. Among the venom constituents, only melittin caused contractile and morphological effects; other peptides, such as apamin and mastparan; enzymes, such as phospholipase A2; and low-molecular-weight compounds, such as histamine and dopamine, did not. Treatment with 4.5 micrograms/ml melittin, which accounts for about half the dry weight of the venom, induced the same cardiotoxic effects as treatment with 9.0 micrograms/ml whole venom; these effects were a transient increase in the spontaneous beating rate, then a decrease, then cessation of beating, and finally, morphological degeneration. The cardiotoxicity of whole bee venom was completely destroyed by pretreatment of the venom with antimelittin antibody. These results suggest that bee venom cardiotoxicity is attributable to melittin. When spontaneous beating ceased following the addition of melittin or whole venom, an increase in systolic [Ca2+]i, was observed. On further incubation with melittin or bee venom, morphological injury, such as balloon degeneration, occurred concomitant with a further increase in the [Ca2+]i. An extracellular Ca2+ concentration of more than 10(-6) M was necessary for morphological injury. Melittin depolarized the maximum diastolic potentials, inhibited the generation of action potentials, and induced an increase in [Na+]i. Cells were protected against the melittin-induced increase in [Ca2+]i by pretreatment with bepridil, an inhibitor of Na(+)-Ca2+ exchange, but not by Ca2+ channel blockers such as verapamil. These observations suggest that the melittin-induced increase in [Ca2+]i was due to entry of extracellular Ca2+ via the sarcolemmal Na(+)-Ca+ exchange system.

Antitumor activities of a new indolocarbazole substance, NB-506, and establishment of NB-506-resistant cell lines, SBC-3/NB

The novel anticancer glucosyl derivative of indolo-carbazole (NB-506), an inhibitor of DNA topoisomerase I, exhibited strong in vitro cytotoxicity against various human cancer cell lines. In order to elucidate its cytotoxic mechanisms, we established nine NB-506-resistant sublines with different resistance ratios from human small cell lung cancer cells (SBC-3/P) by stepwise and brief exposure (24 h) to NB-506. Among them, SBC-3/NB#9 was 454 times more resistant to NB-506 than the parent cell line. The SBC-3/NB#9 cells showed cross-resistance only to topoisomerase I inhibitors, such as 11,7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecia and 7-ethyl-10-hydroxy-camptothecin, and not to other anticancer drugs, such as vincristine, vinblastine, Adriamycin, etoposide, and teniposide. These results indicate that the difference on the effect of topoisomerase I was considered to be related to a resistance mechanism. The topoisomerase I activities of nuclear extracts eluted from SBC-3/NB#9 cells was only one-tenth of the parent cell activity. A Western blotting study indicated that this lower activity was due to a lower amount of DNA topoisomerase I. Furthermore, we found correlations between topoisomerase I activity and sensitivity to NB-506 in sublines with different degrees of resistance. Accumulation of 3H-labeled NB-506 by SBC-3/NB#9 cells was only one-fifth of that by the parent cells, whereas intracellular accumulation of 3H-labeled camptothecin by both cell lines did not differ. The reduction of accumulation was specific to NB-506, and this result may explain why the resistance ratio for NB-506 was higher than those for 11,7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin and 7-ethyl-10-hydroxy-camptothecin.

Manipulation of the lighting schedule can modify the pharmacological effects of theophylline in chick embryos

The effect of the lighting schedule on the pharmacological action of theophylline was studied in chick embryos. Fertile eggs of White Leghorns were incubated and investigated, on two occasions, under constant light conditions or under constant dark conditions. A single injection of theophylline 2.14, 4.29, 8.57 and 17.14 mg/egg into the air sac of fertile eggs was carried out on the 16th day of incubation. Electrocardiograms (ECGs) were recorded 0 to 60 min after drug injection. After drug injection, heart rate increased under constant light conditions, but decreased under dark conditions. In addition, arrhythmia was produced by theophylline, 17.14 mg/egg, under constant dark conditions. These results indicate that the manipulation of the lighting schedule may have a marked influence on the pharmacological effects of theophylline in chick embryos.

The scid factor on human chromosome 8 restores V(D)J recombination in addition to double-strand break repair

The murine severe combined immune deficiency mutation (scid) is characterized by a lack of B- and T-lymphoid cells due to a defect in lymphoid V(D)J recombination. Moreover, defective rejoining of DNA double-strand breaks (dsb) in scid cells also results in a marked increase in sensitivity to ionizing radiation. Recently, the putative human homologue of the murine scid gene locus, HYRC1, was assigned to human chromosome 8q11, based on the radiation sensitivity of scid cells as compared to scid:human cell hybrids carrying portions of human chromosome 8. Given the precedent (e.g., ataxia-telangiectasia) for genes other than the affected one being able to complement radiation defects, we were interested in determining if the V(D)J recombination defect was also corrected by the HYRC1 locus. The V(D)J recombination analysis using extrachromosomal DNA substrates in control scid cells (SC3VA2) versus complemented cells (RD13B2) indicates that the radiation sensitivity-complemented cells (RD13B2) are also fully complemented for the V(D)J recombination reaction, whereas the control (uncomplemented) cells (SC3VA2) fail to carry out V(D)J recombination normally. Slightly over 60% of the radiation-induced dsb are rejoined even in scid cells, and this alternative pathway is temperature sensitive. Only the remaining 30-35% of dsb require the introduction of the HYRC1 locus, and this pathway is not temperature sensitive. This merely partial contribution of the scid factor to the repair process suggests the presence of another pathway of dsb repair. Our results indicate that the HYRC1 locus, assigned to human chromosome 8q11, encodes the scid factor, which is involved in all V(D)J recombination coding joint formation and in 30-35% of dsb repair by the temperature-resistant pathway.

Signalling drug-induced rash with 36 drugs recently marketed in the United Kingdom and studied by Prescription-Event Monitoring

This study examines skin rash, as a reported event, in the patients who used one of the 36 drugs recently released to the UK market and studied by Prescription-Event Monitoring between 1985 and 1992. The results are also compared to the voluntary reports on rash as a possible adverse drug reaction sent to the Committee on Safety of Medicines (CSM). Specific types of skin rash (e.g. exfoliative dermatitis) are excluded. The rate of rash has been calculated for 2 periods, the first month (T1) and the subsequent 5 months (T2) after the first prescription for the drug. Despite the heterogeneity of the patient groups, the rate for rash between the 2nd and 6th months was consistent in the 36 drugs and probably represented the baseline rate of rash due to a variety of nonspecific causes. This rate (T2) was around 1 per 1,000 patients per month (ranging from 0.5 to 2 per 1,000 patients per month). On the other hand, in the first month after the first prescription for the drug, the rate (T1) varied substantially from 0.9 to 6.4 per 1,000 patients per month. Diltiazem had the highest first monthly rate. These rates are listed for the 36 drugs. The difference of the rates was tested by 2 methods: a standard statistical test assuming a Poisson model and a method based on the ratio of the rates for the 2 periods. When the 2 rates (T1 and T2) were similar to each other, drug induced rash was considered to be rare.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical evidence that tumors elicit the synthesis of estrogen receptors in the submandibular gland of female rats

We have demonstrated the presence of estrogen receptor mRNA and the mature protein in the cytoplasm and nucleus, respectively, of a 9,10-dimethyl-1,2-benzathracene-induced submandibular gland tumor in female rats. We have previously shown that progesterone receptors are also present in human salivary gland tumors. These results suggest that endocrine therapy may be effective in treatment of submandibular gland tumors.

[Pattern-reversal visual evoked potentials dissociated vertical deviation]

We recorded pattern-reversal visual evoked potentials (P-VEP) from dissociated vertical deviation (DVD) patients to evaluate the sensory system abnormalities in DVD. 91 DVD patients with good visual acuity were studied. Normal subjects and horizontal strabismic patients without DVD were compared for evaluation. Transient and steady state P-VEPs were recorded from three EEG electrodes placed on the posterior scalp. Half-field checker-board reversal stimulation was applied to stimulate monocular temporal retina and responses from right and left hemispheres were also compared for evaluation. Paradoxical lateralization was observed in all normal subjects. Abnormal P-VEPs were observed in 4 of 20 (20%) horizontal strabismic patients without DVD when employing the transient stimulation method and in 2 of 8 (25%) when using steady state stimulation. Abnormal P-VEPs were observed in 31 of 67 (46.3%) DVD patients, with the transient stimulation method and in 20 of 25 (80.0%) DVD patients with the steady state stimulation method. The abnormalities were various and diverse. Our observations indicate that DVD patients frequently have an abnormal sensory system detected by P-VEP, and DVD might be a complex and multi-origin condition involving both sensory and motor systems.

Immunohistochemical localization of estrogen receptors in the submandibular gland tumors of female rats

The localization of estrogen receptors (EsR) in the tumor tissues of submandibular glands was examined in female rats, using the indirect immunoperoxidase method in combination with the in situ hybridization technique. Tumors were experimentally produced by 9,10-dimethyl-1,2-benzanthracene (DMBA), and the tumor tissues were fixed with formalin or paraformaldehyde and then embedded in paraffin. In the DMBA-induced submandibular gland tumors, immunoreactivity to EsR-peroxidase conjugate was found in nuclei of the tumor cells which occupied the peripheral rim of the tumor cell nests. In contrast, the reactivity in the normal submandibular glands without tumor was mostly confined to nuclei of the duct cells. When EsR mRNA expression was analyzed in the tumor tissue by in situ hybridization with a cDNA probe, its distribution was identical with that of immunoreactivity to EsR. These data suggest that the ductal cells of the submandibular gland are responsive to ovarial steroids, and that estrogens may play an important role in the maintenance of growth of the submandibular gland tumors.

Establishment of a human small-cell lung-cancer subline resistant to okadaic acid

Okadaic acid (OA), a specific protein phosphatase inhibitor, has various biological functions. To elucidate the mechanism of OA resistance, we have established a small-cell lung-cancer subline (H69/OA100) resistant to the growth-inhibitory effect of OA; this was done by using the parental cell line (H69) and increasing the concentration of OA. H69/OA100 was about 8 times more resistant to OA than H69. Intracellular retention of the fluorescent OA derivative in H69/OA100 was the same as that in H69. The catalytic activity of protein phosphatase from H69/OA100 was significantly reduced compared with that from H69. The protein phosphatase from H69/OA100 was 3.6 times more resistant to OA than that from H69. We examined the effect of OA on the activity of the immunoprecipitated protein phosphatase type I (PPI) and type 2A (PP2A) from the 2 cell lines. The PPI and PP2A from H69/OA100 showed more resistance to OA than those from H69. We next examined the effect of OA on the cell cycle of H69 and H69/OA100. In H69, G2/M block was observed at an OA concentration of 30 ng/ml whereas in H69/OA100, no G2/M block was observed at concentrations up to 100 ng/ml OA. We finally evaluated the amount of p34cdc2 kinase expression and the phosphorylation status of p34cdc2. There was no difference in p34cdc2 expression between H69 and H69/OA100 at several concentrations of OA. However, dephosphorylation of p34cdc2 was observed at 30 ng/ml OA in H69, but not in H69/OA100 up to 100 ng/ml OA. These data suggest that the resistance to OA and the resistance of the cell-cycle block to OA in H69/OA100 might be due to alteration of protein phosphatase activity.

[Observation of the eyelid structure with opening and closing of the eye in magnetic resonance imaging]

To confirm the changes in the upper eyelid structure during normal movements such as opening and closing we observed the changes with magnetic resonance imaging and obtained the following results. (1) In the anterior lobe of the upper eyelid, the lower part moves more than the upper part. (2) The tarsus slides toward posterior and upper direction when the eye opens. (3) The orbital septum and the orbital fat move posteriorly and thicken when the eye opens. (4) When the eye opens Whitnall's ligament moves posteriorly with a little change of the acting vector direction of the levator muscle. (5) Aponeurosis of the levator muscle clearly separates from Müller's muscle when the eye opens. (6) We suspected that there is some suspending tissue of Whitnall's ligament that consists of a membranous or mesh-like structure in the orbital fat above the levator muscle.

Establishment of a CPT-11-resistant human ovarian cancer cell line

A camptothecin analog, ((4s)-4,11-diethyl-4-hydroxy-9-[(4- piperidinopiperidino)carbonyloxy]dione hydrochloride trihydrate), (CPT-11), is a recently developed topoisomerase I (Topo I) inhibitor which attracts the attention of clinicians because of its high antitumor activity. We established a CPT-11-resistant human ovarian cell line, HAC2/CPT, from the parental HAC2 cell line. An in vitro drug sensitivity assay revealed that HAC2/CPT was 9.7 and 4.7 times as resistant as HAC2 to CPT-11 and 7-ethyl-10-hydroxy-CPT-11 (SN-38), an active metabolite of CPT-11, respectively. HAC2/CPT showed no cross-resistance to other drugs tested (adriamycin, etoposide, cisplatin and Taxol), suggesting that HAC2/CPT acquired a phenotype specifically resistant to the Topo I inhibitor. In order to elucidate the mechanism of the resistance, we measured Topo I activity of HAC2 and HAC2/CPT. The activity of Topo I of HAC2/CPT was reduced to half of that of the parental HAC2 cells. To determine the cause of the decreased activity of Topo I, the mutation of the Topo I gene was searched for by the polymerase chain reaction and the reverse transcriptase analysis. Topo I gene mutation was not detected. The amount of Topo I protein was measured by immunoblotting and a marked decrease of Topo I protein was observed in HAC2/CPT. These results suggest that the decreased protein content of Topo I causes the decreased activity of Topo I and the decreased sensitivity of HAC2/CPT to Topo I inhibitors.

Ouabain-resistant non-small-cell lung-cancer cell line shows collateral sensitivity to cis-diamminedichloroplatinum(II) (CDDP)

We have reported that the cellular uptake of cis-diamminedichloroplatinum(II) (CDDP) was inhibited by an Na+,K(+)-adenosine triphosphatase (ATPase) inhibitor, ouabain, in a human non-small-cell lung-cancer cell line, PC-14, but not in its CDDP-resistant cell line, PC-14/CDDP. [3H]Ouabain binding of PC-14/CDDP was about 50% lower than that of PC-14. Accordingly, we speculated that a decrease in Na+,K(+)-ATPase activity in PC-14/CDDP might contribute to the decrease in cellular CDDP accumulation. To clarify the relationship between the activity or expression of Na+,K(+)-ATPase and cellular CDDP accumulation, we established an ouabain-resistant non-small-cell lung-cancer cell line (PC-14/OB300), which showed 1.9-fold resistance to the cytotoxicity of ouabain. Interestingly, this cell line was 4.2-fold more sensitive to CDDP than PC-14. The accumulation of CDDP in PC-14/OB300 was increased to 2.7-fold that in PC-14. This elevation of CDDP accumulation was not considered to be caused by increased passive diffusion, because the accumulation of CDDP in PC-14/OB300 was also inhibited by ouabain compared to PC-14. As one of the indices of Na+,K(+)-ATPase activity, we determined cellular 86Rb+ influx rates. The 86Rb+ influx rate was 1.5-fold higher in PC-14/OB300 and fell to 0.7-fold in PC-14/CDDP compared with PC-14. The mRNA expression of Na+,K(+)-ATPase was increased in PC-14/OB300 and decreased in PC-14/CDDP. There was no difference in cellular [3H]ouabain binding between PC-14/OB300 and PC-14. It is possible that Na+,K(+)-ATPase of PC-14/OB300 has a different affinity for ouabain from that of PC-14. Our results suggest that the enzyme activity or the level of expression of Na+,K(+)-ATPase may contribute to the cellular uptake of CDDP and determine the sensitivity to CDDP.

Turbidimetric latex agglutination inhibition immunoassay for primidone

We have developed a quick, highly sensitive immunoassay method for drugs by latex agglutination inhibition. An antiserum against primidone (PRM) was obtained by immunizing rabbits with PRM-bovine serum albumin conjugate. PRM-rabbit serum albumin conjugate sensitized latex was agglutinated with diluted antiserum, and the agglutination was inhibited by free PRM quantitatively. Turbidity of the agglutination suspension was measured by spectrophotometry as absorbance. Larger latex gave higher sensitivity than the smaller, because its agglutination was inhibited more intensely by free PRM. The assay values of this method were correlated well with those obtained by an enzyme immunoassay method.

A novel antitumor antibiotic, KW-2189 is activated by carboxyl esterase and induces DNA strand breaks in human small cell lung cancer cells

KW-2189 has been selected as a lead compound for clinical trial among duocarmycin derivatives with structural similarity to CC-1065, a cyclopropylpyrroloindole. The purpose of this study was to examine the DNA-binding potency and the mechanisms of cytotoxicity of KW-2189. In order to analyze DNA-binding activity of KW-2189, plasmid pBR322 was treated with KW-2189 with or without pretreatment with carboxyl esterase, which we demonstrated to be an activating enzyme, and the products were examined by agarose gel electrophoresis and restriction enzyme analysis. Cytotoxic activity was examined by exposing a human small cell lung cancer cell line, NCI-H69 to KW-2189 with or without carboxyl esterase. Alkaline elution was performed to examine whether KW-2189 induces DNA strand breaks. DNA treated with KW-2189 and carboxyl esterase migrated faster than KW-2189-treated DNA, which migrated at the same rate as untreated DNA. In addition DNA treated with esterase-activated KW-2189 was protected from digestion by some restriction enzymes. KW-2189 showed concentration- and time-dependent growth inhibitory effect with IC50 values (drug concentration required for 50% growth inhibition) of 58 nM (96 h) to 1900 nM (1 h) in H69 cells. The IC50 values of 4-h exposure of H69 to KW-2189 with 0, 26, 130, 650 mU/ml carboxyl esterase were 460, 120, 30, and 7 nM, respectively. Time-dependent enhancement of cytotoxicity by carboxyl esterase was also observed. KW-2189 induced DNA strand breaks in H69 cells in a concentration-dependent manner around the IC50 value. We conclude that 1) KW-2189 is activated by carboxyl esterase to its active form(s), 2) activated KW-2189 has a stronger DNA-binding activity and cytotoxicity than KW-2189, 3) DNA cleavage is one of the major mechanisms of KW-2189-mediated cytotoxicity.

[A pregnant woman with convulsion treated with diazepam which was reversed with flumazenil just prior to cesarean section]

A 37 year-old female in 36th week gestation with convulsion treated with intravenous diazepam underwent an emergency cesarean section. Just prior to induction of anesthesia flumazenil was administrated intravenously to reverse the effects of diazepam in both mother and fetus. Cesarean section was successful under general anesthesia (N2O-pentazocine). The neonate's Apgar score was 6 points at 1 minute and 7 points at 5 minutes after delivery. We conclude that intravenous administration of flumazenil just prior to Cesarean section is effective in a patient with convulsion treated with diazepam.

[Changes in liver tissue amino acids during hemorrhagic shock]

Changes in amino acids in liver tissue during hemorrhagic shock were examined in eight mature mongrel dogs using the microdialysis method. The mean blood pressure was maintained at 50 mmHg by exsanguination, and the values of liver tissue amino acids after 30 minutes showed significant decreases of aspartate, glutamate, histidine, glutamine, glycine and taurine. The decrease of taurine was especially marked. The values dropped further 30 minutes after returning the blood into circulation with some exceptions. These results suggest the possibility that hemorrhagic shock causes reduction in uptake of amino acids by the liver or consumption of amino acids in the liver, and that bile acid metabolism appears to be disturbed by the marked drop in the taurine level. It is necessary to give careful consideration to the possible existence of reduced amino acid metabolism in the liver in the treatment of hemorrhagic shock.

Characterization of a taxol-resistant human small-cell lung cancer cell line

Taxol is a novel anticancer agent with activity against a broad range of tumors. It has a unique ability to stabilize polymerized tubulin into microtubule bundles within the cell. We have established a taxol-resistant human small-cell lung cancer cell line (H69/Txl) by exposing H69 cells to stepwise increases in taxol concentration. The resistance of H69/Txl cells to taxol was 4.7-fold that of the original H69 cells: the IC50 values for H69 and H69/Txl were 113.7 +/- 56.54 nM and 538.7 +/- 214.7 nM by the tetrazolium dye assay, respectively. Removal of the drug from the medium resulted in a 38% decrease in the growth rate of H69/Txl as compared with that in the presence of 30 nM taxol, suggesting that the growth of H69/Txl was partially dependent on taxol. H69/Txl showed higher sensitivity to vinca alkaloids such as vindesine, vincristine and vinblastine than the parental H69. There was no significant difference in intracellular [3H]taxol content between H69 and H69/Txl cells. No MDR-1 mRNA was detected in H69/Txl by the reverse transcription polymerase chain reaction. There was no significant difference of total and polymerized tubulin content between H69 and H69/Txl cells. Altered mobility of one of the alpha-tubulin isoforms in H69/Txl was revealed by using isoelectric focusing and Western blotting with anti-alpha-tubulin antibody. In H69, two alpha-tubulin isoforms were observed, whereas three were evident in H69/Txl, two of them comigrating with the isoforms of H69 and the other being more acidic. We observed the increased acetylation of alpha-tubulin in H69/Txl cells as compared with that in H69 cells. The acetylation of alpha-tubulin may be responsible for the taxol resistance and/or taxol-dependent growth of H69/Txl.

The effects of X-ray energy and an iodine-based contrast agent on chromosome aberrations

A study was undertaken to evaluate the effect of combining irradiation with X rays of various energies and an iodine-based contrast agent on the induction of chromosome aberrations in the peripheral lymphocytes of blood samples taken from healthy young donors. Although no enhancement of the effect of radiation was induced when blood samples with the iodine-based contrast agent were given 35 kV X irradiation, an 80 kV X-ray exposure induced an enhanced level of chromosome aberrations, and at 250 kV X irradiation, an enhancement of the frequencies of chromosome aberrations was seen in blood samples with the iodine-based contrast agent, especially when a Lucite phantom was employed in studies to increase the scattered rays. It was thus shown by microdosimetric analysis that X irradiation combined with an iodine-based contrast agent causes an enhancement of the absorbed radiation dose, which is dependent on the X-ray energies employed. This phenomenon may have clinical use in the radiotherapeutic management of tumors, although further extensive studies of tumor vascularity must be pursued before this can be applied clinically.

Characterization of an etoposide-resistant human ovarian cancer cell line

Etoposide (VP-16) is one of the most important anticancer agents available and is used in many chemotherapeutic regimens. To characterize resistance to this drug, we established a VP-16-resistant human ovarian cancer cell line, SKOV3/VP, by continuous stepwise exposure of SKOV3 cells to VP-16. The degree of resistance to VP-16 of SKOV3/VP was about 25 times that of the parent cell line (SKOV3), and SKOV3/VP showed cross-resistance to teniposide, adriamycin, CPT-11, and vincristine. The accumulation of [3H]-VP-16 observed in SKOV3/VP cells was about half that seen in SKOV3 cells, and the accumulation of Adriamycin by this resistant cell line was also lower than that of its parent. Overexpression of neither the multidrug resistance gene mdr-1, the multidrug-resistance-associated protein (mrp) gene, nor P-glycoprotein was detected using reverse transcriptase-polymerase chain reaction analysis and flow cytometry with MRK-16, a monoclonal antibody against P-glycoprotein. The topoisomerase II activity of nuclear extracts from SKOV3/VP cells was lower than that from the parental cells, as was the amount of DNA topoisomerase II, demonstrated by immunoblotting. These results suggest that the mechanism responsible for the multidrug resistance of this cell line may be attributable to changes on its DNA topoisomerase II and to its reduced accumulation of the drugs as compared with the parental line SKOV3.

7-Ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxy camptothecin: mechanism of resistance and clinical trials

The camptothecin derivative 7-ethyl-10-[4-(1-piperidino)-1-piperidino]-carbonyloxy camptothecin (CPT-11) has attracted the attention of clinicians because of its high antitumor activity against refractory solid cancers. We established two CPT-11-resistant cell lines, a non-small-cell lung-cancer cell line (PC-7/CPT-11) from the parental PC-7 line and an ovarian cancer cell line (HAC-2/CPT-11) from the parental HAC-2 line. The mechanisms of resistance to CPT-11 in PC-7/CPT-11 cells were reduced conversion of CPT-11 to its active metabolite SN-38 and point mutation topoisomerase I. Those in HAC-2/CPT-11 cells were reduction of topoisomerase I activity and decreased sensitivity of topoisomerase to topoisomerase I inhibitors. No point mutation of the topoisomerase was observed in HAC-2/CPT-11 cells. We conducted two phase I trials using CPT-11 in combination with other anticancer agents. One was a phase I trial of CPT-11 and cisplatin given with a fixed dose of vindesine to patients with advanced non-small-cell lung-cancer and the other was a phase I study on a topoisomerase-targeting combination of CPT-11 and etoposide (VP-16) in patients with various malignant solid tumors. The results of the first trial indicated that the recommended dose of CPT-11 for phase II studies was 80 mg/m2 combined with 3 mg/m2 vindesine on days 1 and 8 and 60 mg/m2 cisplatin on day 1. In the second trial, the recommended dose of CPT-11/VP-16 given with recombinant granulocyte colony-stimulating factor (on days 4-17) was found to be 60/60 mg/m2. In both trials, diarrhea and granulocytopenia were considered to be dose-limiting toxicities.

Suramin inhibits the phosphorylation and catalytic activity of DNA topoisomerase II in human lung cancer cells

Suramin is a prototype of a new class of anticancer drugs. We investigated the action of suramin on the signal transduction pathways to DNA topoisomerase II (Topo II). Suramin showed a growth-inhibitory effect on a human lung cancer cell line (PC-9) with an IC50 of about 160 micrograms/ml. Suramin inhibited the catalytic activity of Topo II with an IC50 of about 100 micrograms/ml without stabilization of the cleavable complex of DNA and Topo II. Suramin decreased the phosphorylation of Topo II with an IC50 of 175 micrograms/ml, but did not change the degree of Topo II expression. These IC50 values for inhibition of catalytic activity and phosphorylation of Topo II were equivalent to the growth-inhibitory dose determined by tetrazolium dye assay. Phosphorylation of the tyrosine residues of Topo II was not changed by suramin. In the presence of okadaic acid, a potent inhibitor of serine/threonine protein phosphatase, suramin also decreased the phosphorylation of Topo II, suggesting that the drug did not act on the serine/threonine protein phosphatases inhibited by okadaic acid. Suramin also inhibited the protein kinase C (PKC) activity of PC-9 cells. These results suggest that suramin decreases the phosphorylation of Topo II mediated by PKC. This effect of suramin might cause the inhibition of Topo II activity resulting in the growth inhibition of tumor cells.

Cis-diamminedichloroplatinum(II) inhibits p34cdc2 protein kinase in human lung-cancer cells

cis-Diamminedichloroplatinum(II) (CDDP) induced G2-phase arrest in PC-9 human cancer cells. To elucidate how CDDP acts on cell-cycle regulation, we analyzed the effect of CDDP on cell-cycle regulators such as p34cdc2 protein kinase. p34cdc2 protein kinase activity was maximum in G2 phase and decreased after G2/M transition in synchronized PC-9 human lung cancer cells. Evidence for a phosphorylated p34cdc2 protein kinase complexed with cyclin B was obtained from cells in G2 phase and the p34cdc2 protein kinase appeared to be dephosphorylated at M phase. After exposure to CDDP in G1 phase, PC-9 cells were arrested in G2 phase. The activation of p34cdc2 protein kinase was inhibited by CDDP. Cyclin A and wee-I kinase were not affected by the exposure to CDDP. Cyclin B was degraded in M phase in PC-9 cells. Exposure to CDDP did not affect the degradation of cyclin B. Our data suggest that the effect of CDDP on cell-cycle phase might be regulated by the dephosphorylation of p34cdc2 protein kinase. To determine whether the p34cdc2 protein kinase is a primary target for CDDP, we examined the direct effect of CDDP on tyrosine dephosphorylation of p34cdc2 protein kinase in cellular extracts. Cell lysates from synchronized PC-9 in G2 phase were immunoprecipitated with p13-Sepharose beads. In vitro dephosphorylation of phosphotyrosine of p34cdc2 protein kinase was observed after exposure to okadaic acid in a concentration-dependent manner. The dephosphorylation of p34cdc2 protein kinase by okadaic acid was inhibited by CDDP. We hypothesize that inhibition of p34cdc2 dephorphorylation by CDDP is important for its growth-inhibiting properties.

[The effects of sevoflurane anesthesia with hypothermia on ischemic brain cellular respiration]

We examined the effects of sevoflurane anesthesia with hypothermia on ischemic brain cellular respiration using Wistar strain rats. Ischemia was induced by decapitation. L/P in brain increased during no anesthesia-normothermia-ischemia (1), then gradually, but not fully recovered during 2.5% sevoflurane anesthesia-normothermia-ischemia (2) and during 2.5% sevoflurane anesthesia-hypothermia-ischemia (3). Energy charge decreased during (1) and slight recovery was observed during (3). Respiratory control ratio in brain mitochondria decreased during (1) and recovery during (2) and (3) was slight. No recovery was observed in ADP/O. These findings indicate that during sevoflurane anesthesia with hypothermia, ischemic brain energy metabolism has an effect not on the mitochondrial energy producing processes but on the consuming system.

Novel water-soluble derivatives of docosahexaenoic acid increase diacylglycerol production mediated by phosphatidylcholine-specific phospholipase C

The effect of ascorbic acid 6-docosahexaenoate (DHA-VC) on the phospholipase-C-mediated hydrolysis of phosphatidylcholine was investigated. In human non-small cell lung cancer cells (PC-14) exposed to DHA-VC for 24 hr, a dose-dependent increase in phosphatidylcholine-specific phospholipase C (PC-PLC) activity was seen. PC-PLC activity in whole-cell homogenate of PC-14 cells was increased about 2.5-fold by 2 hr of treatment with DHA-VC (20 micrograms/ml). Treatment with DHA-VC also augmented PC-PLC activity in the crude membrane extract. On the other hand, DHA-VC inhibited the activity of phospholipase A2 (ID50 = 800 micrograms/ml). Another water-soluble analog, choline docosahexaenoate, also stimulated PC-PLC activity. To explore the effect of DHA-VC on phosphatidylcholine turnover, we analyzed phospholipids labeled with [14C] choline or [3H]myristate by thin-layer chromatography, and found that the amount of [14C]- and [3H]-labeled phosphatidylcholine was constant in the presence of DHA-VC. These results suggest that phosphatidylcholine turnover was not influenced by DHA-VC. DHA-VC treatment increased protein kinase C activity of the cells in the late phase (120 min), suggesting that DHA-VC-induced diacylglycerol production mediated by PC-PLC causes protein kinase C activation. Considering that significant inhibition of DNA synthesis occurred 12 hr after 2 hr of treatment with DHA-VC (20 micrograms/ml), DHA-VC-induced PC-PLC activation seems to be an early event in DHA-VC-induced cytotoxicity, which suggests that the effects of DHA-VC on signal transduction pathways may play an important role in the cytotoxicity of DHA-VC.

[The development of occlusion amblyopia following atropine therapy for strabismic amblyopia]

For the treatment of strabismic amblyopia the authors have used atropine in the sound eye under usual optical correction as soon as central fixation of the amblyopic eye is secured by means of proceeding occlusion therapy. Although there may be little effect of occlusion in atropine therapy, six children under five years of age developed amblyopia in their sound eyes. In every case, the first sign of developing amblyopia was the decrease of fixation ability in the sound eye in a binocular fixation test prior to the reduction of visual acuity. On the other hand, fixation ability of the originally amblyopic eye was reinforced more and more not only during atropinization but after its finish until deep amblyopia developed in the sound eye. In three cases, eccentric fixation occurred at 7, 9, and 17 weeks after atropinization. These facts suggest that occlusion amblyopia following atropine therapy is not the result of deprivation but is due to the reversal of the eye used for fixation. Strabismic amblyopia may have the tendency toward an alternation between fixation abilities of the two eyes and such a binocular sensory anomaly may cause strabismic amblyopia itself.

Apoptosis of lung cancer cells caused by some anti-cancer agents (MMC, CPT-11, ADM) is inhibited by bcl-2

To determine whether the apoptotic cell death induced by anti-cancer agents could be inhibited by bcl-2, we established a bcl-2-transfected human small cell lung cancer cell line, SBC-3/Bcl2. SBC-3/Bcl2 showed higher resistance to ADM, CPT-11 and MMC compared with the parental line SBC-3, with relative resistance values of 3.4, 7.6 and 5.7, respectively. However, there was no difference in sensitivity to CDDP, VP-16, ACNU, MTX and taxol between SBC-3 and SBC-3/Bcl2. Agarose gel electrophoresis showed typical DNA fragmentation of SBC-3 following treatment with CPT-11 or MMC, in a concentration-dependent manner. In contrast, the same concentration of the drugs did not induce DNA fragmentation in SBC-3/Bcl2. Treatment with CDDP resulted in the same degree of DNA fragmentation in SBC-3 and SBC-3/Bcl2. These studies indicate that bcl-2 can modulate the cytotoxicity of some anti-cancer agents by inhibiting the process of apoptosis.

The Effect of sevoflurane on rat liver mitochondrial respiration

The effect of sevoflurane on rat liver mitochondrial respiration has been investigated with a Clark type oxygen electrode at 25 degrees C, pH 7.4. The higher susceptibility of NADH-linked substrate (glutamate) oxidation (with respect to succinate oxidation) to the damages by sevoflurane has been confirmed.

Hyperthermic enhancement of cell killing by five platinum complexes in human malignant melanoma cells grown as monolayer cultures and multicellular spheroids

The cytotoxic properties of hyperthermia combined with cis-diammine-dichroloplatinum(II) (CDDP), and recently developed platinum complexes, (Glycolato-O-O')diammineplatinum(II) (254-S), cis-1-1-cyclobutane-dicarboxylate-(R)-2-methyl-1-4-butanediammine platinum(II) (NK-121), cis-diammine(1,1-cyclobutanedicarboxylato)platinum(II) (CBDCA), and (-)-R-[2-(aminomethyl)pyrrolodine](1,1- cyclobutanedicarboxylato)-platinum(II)monohydrate (DWA-2114R) were studied in vitro in monolayer cultures and multicellular spheroids of HMV-I human malignant melanoma cells. Hyperthermia at 44 degrees C for 30 min was applied during the latter part of 1 hr drug exposure. Cell survival was compared after drug treatments in cells exposed or not exposed to heat. Cytotoxicity was assessed by clonogenic assays. In exponentially growing monolayer cultures, marked hyperthermic sensitization was observed by each of the five platinum complexes studied. The dose modifying factors obtained were almost the same in these drugs. Unlike monolayer cells, the spheroids were appreciably different with regard to hyperthermic sensitization among platinum complexes. The order of the magnitude was as follows: CDDP, DWA-2114R, 254-S, CBDCA, and NK-121. In the low dose region, however, 254-S was the most thermally sensitized. These results suggest that the microenvironment factor within spheroids may significantly affect the cytotoxicity of platinum complexes combined with hyperthermia. On the basis of these findings using spheroids, CDDP, DWA2114R, and 254-S appear to be promising platinum complexes for use with hyperthermia clinically as far as hyperthermic sensitization is concerned.

Characteristics of neutron beam generated by 500 MeV proton beam

A neutron irradiation facility was constructed at PARMS, University of Tsukuba to produce an ultrahigh energy neutron beam with a depth dose distribution superior to an x-ray beam generated by a modern linac. This neutron beam was produced from the reaction on a thick uranium target struck by a 500 MeV proton beam from the booster synchrotron of the High Energy Physics Laboratory. The percentage depth dose of this neutron beam was nearly equivalent to that of x-rays around 20 MV and the dose rate was 15 cGy per minute. The relative biological effectiveness (RBE) of this neutron beam has been estimated using the cell inactivation effect and the HMV-I cell line. The survival curve of cells after neutron irradiation has a shoulder with n and Dq of 8 and 2.3 Gy, respectively. The RBE value at the 10(-2) survival level for the present neutron beam as compared with 137Cs gamma rays was 1.24. The results suggest that the biological effects of ultrahigh energy neutrons are not large enough to be useful, although the depth dose distribution of neutrons can be superior to that of high energy linac x-rays.

Detection of topoisomerase I gene point mutation in CPT-11 resistant lung cancer cell line

CPT-11, a recently developed topoisomerase I (Topo I) inhibitor, attracts the attention not only of basic researchers but also of clinicians because of its high antitumor activity. The CPT-11 resistant human lung cancer cell line, PC-7/CPT, showed 10-fold resistance compared to parental cell line, PC-7. The total activity of Topo I in the resistant cell line was one fourth that of the parental sensitive cell line. The Topo I from the resistant cells was also 5-fold more resistant to the inhibitory effect of CPT-11 than that of the parental cells. We speculated that the alteration of the Topo I gene may be responsible for the change in topoisomerase activity of the CPT-11 resistant cell line. Therefore, we analyzed the mutation of Topo I gene using the method of single strand conformation polymorphism of polymerase chain reaction and the reverse transcriptase. We divided Topo I cDNA into ten fragments which overlapped each other and covered whole coding sequences of the Topo I cDNA. We observed mobility shift of two fragments in the PC-7/CPT, suggesting the presence of some mutations in these fragments. We performed the direct-sequencing of these portions by the dideoxy chain termination method and observed an altered sequence having a G to A base change in PC-7/CPT. This base substitution results in replacement of the conserved threonine at 729 position with alanine. These results suggest that the point mutation of Topo I gene is related to the decreases of Topo I activity and the sensitivity to Topo I inhibitor in PC-7/CPT cells.

Alteration of type II regulatory subunit of cAMP-dependent protein kinase in human cisplatin-resistant cells as a basis of collateral sensitivity to 8-chloro-cAMP

A cyclic adenosine 3',5'-monophosphate (cAMP) analogue, 8-chloro-cAMP (8-Cl-cAMP), had a collateral growth-inhibitory effect on a cis-diamminedichloroplatinum(II) (CDDP)-resistant human cancer cell lines (PC-14/CDDP). The non-selective analogues dibutyryl-cAMP, 8-bromo-cAMP and forskolin, which are cAMP agonists, showed far less cytotoxicity than 8-Cl-cAMP in both cell lines. There was no significant difference in cAMP content between PC-14 and PC-14/CDDP. Because 8-Cl-cAMP has been shown to bind selectively to the site I receptor of the type II regulatory subunit (RII) of cAMP-dependent protein kinase, we determined the level of expression of regulatory subunits in PC-14 and PC-14/CDDP cells by photoaffinity labeling. PC-14/CDDP cells had a higher RII level, low site I receptor of type I regulatory subunit (RI) level, and a lower RI/RII ratio than the parental PC-14 cells. Exposure to 8-Cl-cAMP increased the RI and RII level in PC-14/CDDP cells in dose- and time-dependent manners. On the other hand, in parental PC-14 cells, RII was not detected and the levels of RI and RII were not increased by exposure to 8-Cl-cAMP. These results suggested that the change in RI and/or RII levels caused by 8-Cl-cAMP was correlated with 8-Cl-cAMP-induced growth inhibition and that the collateral sensitivity to 8-Cl-cAMP in CDDP-resistant cells was due to the increased RII level. Our results suggest that 8-Cl-cAMP can be used in combination with CDDP and that measurement of RI and RII levels and/or the RI/RII ratio is a useful tool to predict CDDP sensitivity.

Application of immunocryoultramicrotomy to free cells: ultrastructural localization of myeloperoxidase in neutrophils of human peripheral blood

Immunocryoultramicrotomy is generally considered the most suitable method for observing the immunostainings by monoclonal antibodies to intracellular antigens by electron microscopy. However, this procedure with the free cells such as peripheral blood cells or cultured cells is not widely used because of the difficulty in preparing ultrathin frozen sections. We report here a new technique for making ultrathin frozen sections of peripheral blood cells by positioning the cell in a semigelatinized medium for ultrasectioning. Monoclonal antibody against myeloperoxidase (MPO) was reacted with the ultrathin sections made with this new technique to observe the ultrastructural localization of intracellular MPO. MPO was observed in the primary granules of the neutrophils.

[An epidemiogenetic study of typical retinitis pigmentosa in Japan--a preliminary report of nationwide, multicenter study]

We performed a nationwide, multicenter study of typical retinitis pigmentosa with reference to the inheritance patterns of the disease. A total of 253 probands were registered during two months of 1989, and an analysis of the parental consanguinity of 182 probands with the method of inbreeding coefficient enabled us to estimate the relative prevalence of genetic types; autosomal recessive trait: 47.6%; autosomal dominant trait: 17.3%; sporadic cases: 34.6%. A comparison of the results with previous studies has indicated a decrease in the prevalence of the autosomal recessive trait and an increase in the sporadic cases, as would be expected from the decrease in consanguineous marriages and offsprings in the past few decades in Japan. X-linked retinitis pigmentosa was rarely identified, but precise evaluation of its frequency needs further investigation.

A case of splenic vein occlusion caused by the intravenous tumor thrombus of nonfunctioning islet cell carcinoma

We report herein a case of successfully treated advanced, nonfunctioning islet cell carcinoma associated with left-sided portal hypertension. The splenic vein was obstructed by a huge intravenous tumor thrombus developing from the main pancreatic tumor. Direct invasion to adjacent organs such as the spleen, colon, left kidney and stomach was also observed, although liver metastasis was not present. Radical resection was carried out with removal of these five involved organs and the patient is alive without recurrence more than 5 years after surgery.

[Clinico-pathological studies on the effects of preoperative hyperthermo-chemoradiotherapy of advanced esophageal carcinoma]

We report clinico-pathological studies on the effect of preoperative hyperthermia and chemotherapy combined with radiotherapy (HCR) for progress of the local curability of advanced esophageal carcinoma. The subjects of these studies were 17 patients who underwent subtotal esophagectomy after preoperative irradiation 40 Gy from 1980 to 1989, of which 8 patients had HCR, 6 patients irradiation only (R), 3 patients both irradiation and chemotherapy (CR). The clinical response rate of the patients with R or CR was 33% (PR 3, MR 3, NC 3), and the histological effective (Ef3 or Ef2) rate was 56% (Ef3 1, Ef2 4, Ef1 4). The clinical response rate of the patients with HCR was 88% (PR 7, MR 1), and the histological effective rate was 100% (Ef3 1 Ef2 7). HCR was more effective than R or CR for the local lesion of esophageal carcinoma histopathologically (p less than 0.05). However, the survival rate of patients with HCR was similar to R and CR, respectively. These results suggest that further improvement of the heating methods and the methods of combining hyperthermia with irradiation and chemotherapy is needed.

Effects of dietary konjac mannan on serum and liver cholesterol levels and biliary bile acid composition in hamsters

We studied the effect of dietary konjac mannan on serum and liver cholesterol levels and biliary bile acid composition in hamsters. In hamsters fed a control diet supplemented with konjac mannan for 6 weeks, serum and liver cholesterol levels were decreased significantly compared to hamsters fed the control diet. Addition of konjac mannan to the cholesterol-enriched diet reduced the elevation of serum cholesterol caused by feeding cholesterol. However, the absorption of cholesterol from the intestine was not changed between the four groups. The increase in the proportion of chenodeoxycholic acid in biliary bile acids was significantly enhanced in the hamsters fed both cholesterol and konjac mannan compared to hamsters fed the control diet. The change of the bile acid composition may suggest that konjac mannan inhibits the intestinal absorption of bile acids.

Hyperthermic purging in vitro of murine leukemia cells (MK-8057): surviving fractions of normal and leukemic stem cells and the long-term survival of mice injected with the post-hyperthermic leukemia cells

Hyperthermic purging of leukemic cells has been applied in clinical trials, although an accurate evaluation system to compare the effect on leukemia cells with that on normal hemopoietic cells has not been established. We evaluated the heat-sensitivity of murine leukemia cells, MK-8057, and compared differences in heat-sensitivity between surviving fractions of leukemic stem cells (leukemic spleen colony-forming units, L-CFU-S) and normal hemopoietic stem cells (spleen colony-forming units, CFU-S). Using the spleen colony assay, the survival fraction of L-CFU-S was compared with that of CFU-S after various hyperthermic treatments. One of the most efficient conditions, that is, hyperthermia at 42 degrees C for 3 h, allowed only 0.17% of L-CFU-S to survive, whereas 26.5% of normal CFU-S survived. Hyperthermia at 44 degrees C for 45 min further reduced the L-CFU-S (0.13%); however, the relative ratio of L-CFU-S to CFU-S was less than that at 42 degrees C for 3 h, because there was a larger reduction at 44 degrees C in normal CFU-S (5.1%). Recipient mice injected with MK-8057 cells treated with hyperthermia survived longer in proportion to the decreasing number of surviving L-CFU-S injected. This extension of the survival of recipient mice given MK-8057 cells after hyperthermia was also proportional to the estimated survival fraction of L-CFU-S. The survival fraction of MK-8057 cells after hyperthermia that was independently calculated through the extended survival of the recipients showed a good correlation with the surviving fraction of L-CFU-S, seen as the leukemic spleen colonies, at a correlation coefficient of r = 0.985. The number of surviving mice receiving the post-hyperthermic MK-8057 cells and the number of L-CFU-S calculated to have been injected had a relationship based on a Poisson distribution. Thus, the calculated results imply that the hyperthermia proportionally targets L-CFU-S, which are the only cells responsible for killing the recipient mice.

[Characterization of ultra high energy neutron beam generated by 500 MeV proton beam]

An ultra high energy neutron facility was constructed at PARMS, University of Tsukuba, to produce a neutron beam superior to an X-ray beam generated by a modern linac in terms of dose distribution. This has been achieved using the reaction on a thick uranium target struck by 500 MeV proton beam from the booster-synchrotron of High Energy Physics Laboratory. The percentage depth dose of this neutron beam is nearly equivalent to that of X-rays at around 20 MV and the dose rate of 15 cGy per minute. Relative biological effectiveness of this neutron beam has been estimated on the cell killing effect by the use of HMV-I cell line. Resultant survival curve of cells after the neutron irradiation shows the shoulder with n and Dq of 8 and 2.3 Gy, respectively. RBE value at 10(-2) survival level for the present neutron, compared with 137Cs gamma-rays is 1.24. The result suggests that the biological effects of high energy neutrons are not practically large enough whenever the depth dose distribution of neutrons becomes superior to high energy linac X-rays.

Structural characterization of natural and recombinant human granulocyte colony-stimulating factors

Granulocyte colony-stimulating factor (G-CSF) is a glycoprotein which stimulates predominantly neutrophilic granulocyte colony formation in mammals. Natural human G-CSF (hG-CSF) and recombinant hG-CSF produced in Chinese hamster ovary (CHO) cells transfected with the cDNA clone for hG-CSF have been purified to apparent homogeneity for structural and biological comparison. The amino acid sequence of recombinant hG-CSF, composed of 174 amino acid residues, was identical with that of natural hG-CSF and also with the sequence predicted from the cDNA. Both forms of hG-CSF have a free Cys-17 and two intramolecular disulfide linkages, between Cys-36 and Cys-42, and between Cys-64 and Cys-74. The O-glycosylation occurred at Thr-133 in both hG-CSFs. Similar CD spectra were obtained for both hG-CSFs. Additionally, both forms showed almost the same biological activities determined by in vitro colony-forming assay and in vivo assay. It is thus concluded that the recombinant hG-CSF is indistinguishable from its natural counterpart and that the former is valuable for more detailed characterization and clinical use.