Evidence for a synergistic interaction between phenytoin and phenobarbital in experimental animals

Combined anticonvulsant effects of phenytoin and phenobarbital in mice and rabbits were studied using the isobolographic method which was based on the plasma concentrations of these drugs. Anticonvulsant activity of test drugs alone or in combination was determined by the method of maximal electroshock seizure test. Response of each animal to drug action was recorded as abolition of the tonic hindlimb extensor component of maximal electroshock seizure. It was demonstrated that the minimal effective plasma concentrations of phenytoin and phenobarbital alone for protection against maximal electroshock seizure was 5.9 +/- 0.2 and 18.1 +/- 0.4 microgram/ml (+/- SE) in mice and 14.7 +/- 0.5 and 17.5 +/- 0.6 microgram/ml (+/-SE) in rabbits, respectively. Isobolograms for mice and rabbits were constructed by identifying and plotting each responder and nonresponder for its corresponding plasma phenytoin and phenobarbital concentrations when these drugs were given in combination. The isoboles in mice and rabbits were concave bowing toward the origin, indicated synergism (potentiation). The apparent synergism between phenytoin and phenobarbital cannot be explained by changes in the amount of these drugs entering into the brain from the blood, since the relationship between brain and plasma concentrations of either drug was not altered by the presence of the other. These results, therefore, suggest that the synergistic action between these two anticonvulsants occurs within the central nervous system; this provides experimental support for the combined use of phenytoin and phenobarbital in the clinical treatment of epilepsy.

Normalization by cell fusion of sister chromatid exchange in Bloom syndrome lymphocytes

Fusion of fresh lymphocytes from a Bloom syndrome (BS) patient with those of normal subjects or a BS heterozygote resulted in complete normalization of the frequency of sister chromatid exchanges in the chromosomes of BS cells. This normalization took place by the first mitosis in hybrid cells. In contrast, cultivation of BS lymphocytes with those of normal subjects or the BS heterozygote had no effect on sister chromatid exchanges. The cell fusion experiments suggest that the normalization on the sister chromatid exchanges. The cell fusion experiments suggest that the normalization of the sister chromatid exchange frequencies in BS cells can be achieved by factors conserved in the cells of various mammalian species. These findings are compatible with the concept that BS is a recessive genetic mutation at regulatory levels of the DNA repair function.

Differential antagonisms of anticonvulsants to various components of maximal seizures induced by electroshock or pentylenetetrazol in mice

Effects of antiepileptic drugs on various components (TF: tonic extension of forelimb, TH: tonic extension of hindlimb and CL: clonic convulsions or MCL: myoclonus) of maximal seizures induced by electroshock or pentylenetetrazol in mice were examined in order to classify these drugs. In addition, experiment was conducted similarly on the new anti-convulsant agent, 3-sulfamoylmethyl-1,2-benzisoxazole (AD-810), in order to assess this compound on the basis of the results with clinically useful antiepileptic drugs. From the results obtained in the present study, irrespective of the method, i.e. chemically or electrically induced seizures, anticonvulsant drugs tested can be classified into four main groups; 1) drugs (trimethadione, ethosuximide, nitrazepam, diazepam, erthotoin and metharbital) with an effect to antagonize all the whole seizure components. (TF, TH and CL or MCL) in an almost same antagonism, 2) drugs (phenacemide, dipropylacetate, pheneturide, acetylpheneturide and phenobarbital) which inhibit all forms of seizures at relatively dissociated doses for the prevention of each component of seizures, 3) drugs (diphenylhydantoin and carbamazepine) which selectively abolish both components (TF and TH) of tonic seizures, and 4) drugs (acetazolamide, sulthiame and primidone) exclusively blocking TH of tonic seizures. AD-810 demonstrated an antagonistic effect on tonic seizures but no on clonic ones with the same manner as seen with diphenylhydantoin and carbamazepine.

Relationships between plasma concentrations of diphenylhydantoin, phenobarbital, carbamazepine, and 3-sulfamoylmethyl-1,2-benzisoxazole (AD-810), a new anticonvulsant agent, and their anticonvulsant or neurotoxic effects in experimental animals

The relationships between plasma concentrations of diphenylhydantoin (DPH), phenobarbital (PB), carbamazepine (CBZ), and 3-sulfamoylmethyl-1,2-benzisoxazole (AD-810), a new anticonvulsant agent, and their anticonvulsant and neurotoxic effects were studied in various species of animals. Anticonvulsant activities of test drugs were examined by the maximal electroshock seizure (MES) test. Neurotoxicities were determined by the rotorod performance test in mice and rats and by behavioral observations in rabbits, dogs, and monkeys. It was demonstrated that both the anticonvulsant effects and the neurotoxic effects of the drugs tested were more closely correlated with their plasma concentrations than with the dosages administered. There was a critical plasma concentration for each drug to show an anticonvulsant effect or to cause a neurotoxic effect in an individual animal. The critical plasma concentrations for anticonvulsant and neurotoxic effects of each drug were relatively constant among different species, with the exception of DPH in rabbits, which had twice the value in other species. The therapeutic ranges of plasma concentrations of DPH, PB, and CBZ determined in various species of animals coincided well with those recommended clinically. AD-810 was found to be effective against MES without signs of neurological toxicity in the ranges of plasma concentrations of 9.8 to 74.0, 10.8 to 95.0, 9.6 to 117.0, and 12.6 to 96.2 microgram/ml in mice, rats, rabbits, and dogs, respectively. These results seem to suggest that AD-810 may be effective clinically at plasma concentrations above 10 microgram/ml, with a therapeutic range up to 70 microgram/ml, which is much wider than the therapeutic ranges of DPH (10--20 microgram/ml), PB (10--30 microgram/ml), and CBZ (4--10 microgram/ml).

Differential response of sister chromatid exchange and chromosome aberrations to mitomycin C of normal and abnormal human lymphocytic cell lines

Mitomycin C (MMC) induced chromosome aberrations and an increased sister chromatid exchange (SCE) incidence in a cell line derived from normal lymphocytes, whereas in lines originating from cells of chronic lymphocytic leukemia (lines SN1029 and SN1033) and Burkitt lymphoma (lines B35 M and HR1K) MMC caused a striking increase in SCE, but not in the frequency of chromosome abnormalities. The latter may be due to the failure of the cells with chromosome aberrations to survive, possibly related to their high sensitivity to MMC. The increased rate of SCE with MMC treatment was more marked in the neoplastic lymphocytic cells than in the normal ones; the sensitivity of SN1029 and SN1033 cells was 10 times higher and that of B35M and HR1K cells about 5 times higher than that of the normal cells. These observations suggest that the MMC-induced high rate of SCE in the neoplastic cells may in some aspects differ from the mechanism(s) leading to chromosome aberrations; and that SCE is a much more sensitive indicator of MMC effects than chromosome aberrations.

Evaluation of fibergastroscopic biopsy in the diagnosis of gastric cancer: a study of 339 cases

Three hundred and sixty-five biopsies under direct vision, using a fibergastroscope, were performed on 339 patients with gastric cancer from 1966 to 1975. Diagnostic accuracy improved with an increased in the number of biopsy specimens and reached 100% when 6 or more biopsy specimens were obtained. Positive specimens were obtained with 48.5% of the biopsied tissue from the center of the lesion (A), 52.2% from the inner margin of the lesion (B1), 19.6% from the outer margin of the lesion (B2), and 1.6% from the area around the lesion (C). The combined result of the biopsies from A and B1 was highly positive in 49 out of 51 cases (96.1%). Diagnostic accuracy of the early cancer reached 96.9%. This was significantly higher than that of advanced cancer (80.3%). False negative biopsies were found in 51 (16.3%) of the 313 patients who were gastrectomized and diagnosed by histological examinations. Twenty-three of the 27 patients, who were diagnosed as benign either by x-ray or endoscopic examination, and 4 of the 5 patients who were diagnosed as benign under both examinations, were found to have positive results by biopsy. Positive biopsy examination was particularly helpful with patients showing on inconclusive or benign diagnosis by x-ray and/or endoscopic examinations.

Chromosome aberrations induced by monomeric acrylamide in bone marrow and germ cells of mice

Acrylamide induces chromatid exchanges and breaks with considerable frequency in spermatogonia of mice with long-term administration (3 weeks), though not, remarkably, with short-term administration (1--2 weeks. At 12 and 24 h after single injections with 50, 100 and 150 mg/kg acrylamide, evaluation of the cytogenetic effect is difficult in the spermatogonia because of an extreme reduction of mitotic cells. Aneuploid and polyploid cells increase with time after treatment in both marrow and spermatogonial cells, while the aberration frequency shows no increase in marrow after both oral-administration and injection. Evidently the spermatogonia are thus rather more sensitive to acrylamide than marrow cells. On the other hand, the SCE frequency is at the control level in treated subjects in marrow and spermatogonia. Acrylamide induces chain quadrivalents, ring quadrivalents, fragments and univalents which are particularly evident in primary spermatocytes in both oral administration and injection, though it is questionable whether these structural changes deal with spermatogonia, or otherwise with the S-phase primary spermatocytes. There is a possibility that the aberrant cells thus produced can develop into spermatozoa carrying a certain type of reciprocal translocation which leads to semi-sterile progeny. In relation to the above problem detailed investigations into this type of rearrangement in primary spermatocytes are needed.

Effects of mitomycin C on sister chromatid exchange in normal and Bloom's syndrome cells

Bloom's syndrome lymphocytes, which are characterized by a high incidence of sister chromatid exchanges (SCE: 80.6 per cell), were treated with mitomycin C (MMC) and the effect of the chemical on SCE frequency compared with that in normal cells. Raising the concentration of MMC from 1 X 10(-9) to 1 X 10(-7) g/ml led to about 10-fold increase (61.7 SCE per cell) in the SCE frequency over the base line in normal lymphocytes (6.4 SCE per cell), though chromosome aberrations remained at a relatively low frequency. MMC caused about a two-fold rise in SCE in cells of Bloom's syndrome (128.8 SCE at 10(-9) g/ml; 139.3 SCE at 10(-8) g/ml). The frequency of chromosome aberrations in Bloom's syndrome cells at concentrations of MMC of 1 X 10(-9) and 1 X 10(-8) g/ml was 0.350 and 0.825 per cell, respectively, and low when compared to the increased number of SCE. The increased frequency of SCE in normal and Bloom's syndrome cells is in contrast to the reported findings with cells from Fanconi's anemia and xeroderma pigmentosum. The distribution of SCE in MMC-treated normal cell correlates with that of spontaneous SCE in cells of Bloom's syndrome.

The relationship between sister chromatid exchanges and chromosome aberrations in Bloom's syndrome

The distribution of the break points of sister chromatid exchanges (SCE) was compared with that of chromosome aberrations in Bloom's syndrome by using differential sister chromatid staining and banding techniques. A comparison was made of the distribution in chromosomes 1, 2, and 3, since the exact identification of other chromosomes is difficult with the differential sister-chromatid staining technique. It was shown that SCE and chromosome breaks do not necessarily correlate as to location. Some chromosome break points, e.g., 1q21, 1p36, 2q31, 3q12, and 3p13, were common with those of SCE, whereas others (at 1p13, 2p11, 2q11, and 3q11) showed little or no SCE. SCE breaks were not observed in the centromeric regions. In addition, the SCE frequency was examined in Bloom's syndrome cells with and without chromosome aberrations, and no significant differences of SCE frequency were observed between cells with chromatid- or chromosome-type of aberrations and those with normal complements. Banding analyses indicated a nonrandom distribution of chromosome breaks in the lymphocytes and marrow cells of the Bloom's syndrome patient.

Dependency of sister chromatid exchange in T- and B-cells on the incorporation of deoxyribonucleosides into chromosomal DNA

Human T-cells (CCRF-HSB2) did not incorporate tritiated thymidine ([3H]TDR)--1.0-5.0 muCi/ml--into the nuclei, where.as they readily incorporated tritiated deoxycytidine (E13H]CDR). When contamination with pleuropneumonia-like organisms was ruled out, these findings strongly suggested a deficiency of the enzyme thymidine kinase in the cells. Human B-cells (CCRF-SB) and normal T-lymphocytes (NTL) readily incorporated [3H]CDR, [3H]TDR, and tritiated 5-bromodeoxyuridine, and they clearly exhibited differential staining of the sister chromatids (SCD). When nonisotopic bromodeoxyuridine (BUDR), 10(-6)-10(-4) M, was used with the B-cells and NTL, SCD were clearly evident and sister chromatid exchange (SCE) was relatively infrequent; when the concentration was 10(-7) M, SCD staining was poor but the frequency of SCE was high. SCE frequencies in NTL, measured by autoradiography after incorporation of [3H]CDR, were the same as SCE frequencies measured by staining with BUDR at 10(-4) M. In the case of CCRF-HSB2, 10(-4) M BUDR produced relatively high frequencies of SCE as did 10(-7) M BUDR with the former two cells. However, [3H]CDR with CCRF-HSB2 gave relatively low frequencies of SCE, of the magnitude observed after 10(-4) M BUDR was used with NTL and the B-cells. Thus the high frequency of SCE in CCRF-HSB2 cells may have been due to the staining property of chromosomes that had incorporated low levels of BUDR.

Clones of Friend leukemia cells: differences in karyotypes and responsiveness to inducers of differentiation

Several clones of Friend leukemia cells have been established which differ in their chromosome composition. These cells also vary with regard to their responsiveness to DMSO, whereas all are responsive to butyric acid. Hence, there appears to be independent assortment of the ability of a cell line to respond to DMSO and to butyric acid, suggesting a different mechanism of action for each agent. Further, individual Friend cells possess the ability to simultaneously contain chloroacetate esterase and heme--two biochemical properties which have previously been believed to be mutually exclusive.

Differential sensitivity to x-ray of chromosomes of blood T-lymphocytes and B-and T-cell lines

Normal T-lymphocytes, B-cell line (CCRF-SB) and T-cell line (CCRF-HSB-2) cells, all diploid in their chromosome constitution, were exposed in vitro to various doses of X-ray and analyzed at their first mitotic division for structural chromosome abnormalities. The irradiation effects were determined also by a viability test of the cells, using trypan blue dye. The irradiated T-cell line (CCRF-HSB-2) showed a remarkably high frequency of chromosome aberrations, including chromosome and chromatid deletions, chromatid exchanges, dicentrics, rings and acentric fragments. On the other hand, the chromosome aberrations observed in the irradiated B-cell line and normal T-lymphocytes consisted mainly of dicentrics, rings, deletions and acentric fragments; the frequency of chromosome and chromatid deletions was low as compared to that of the T-cell line. The cell viability test showed a singificantly higher percent reduction of viable cells at every dose of X-ray in the irradiated T-cell line than in the B-cell line or the normal T-lymphocytes. It is possible that the increased radiosensitivity of the T-cell line is related to the original malignant nature of the cells, which originated from the lymphocytes of a patient with acute lymphoblastic leukemia.

Increased sister chromatid exchange in bone marrow and blood cells from Bloom's syndrome

Bone-marrow cells from a patient with Bloom's syndrome cultured for 48 h in the presence of BudR exhibited a striking increase in the number of sister chromatid exchanges (SCEs) in comparison to that in the marrow cells of a patient with treated polycythemia vera (PV). Thus, it appears that an increased incidence of SCE in Bloom's syndrome occurs in various differentiated types of cells, not just blood lymphocytes, and constitutes the syndrome's most characteristic cytogenetic feature. In contrast, the incidence of SCE was not increased in marrow cells and lymphocytes of the particular PV patient studied here, whose cells did exhibit increased numbers of chromatid and chromosome gaps and breaks, presumably as result of the patient's earlier treatment. An increased frequency of SCE was demonstrated in Bloom's syndrome lymphocytes using both a technique based on BudR incorporation and one based on labeling with tritated deoxycytidine. This observation constitutes evidence against the increase of SCE being due to an unusual reaction to BudR. By conventional cytogenetic techniques, chromosome instability, including chromatid and chromosome breaks, but no homologous chromatid interchanges were also recognized in Bloom's syndrome bone-marrow cells incubated in vitro (without BudR) for either 1.k or 16 h. This observation points to the existence of chromosome instability in vivo.

Chromosomes and causation of human cancer and leukemia. XII. Banding analysis of abnormal chromosomes in polycythemia vera

The chromosome constitution of bone marrow cells was determined in 13 patients with polycythemia vera (PV). In 5 of these patients definite karyotypic abnormalities were found: 3 with 46,XY,Fq-; 1 with 46,XY,11q-, 13q-; and 1 with missing Y. The latter cytogenetic finding is thought not to be related to the PV. The 4 patients with partial deletions of chromosomes had been treated with 32P, and 3 of them with chemotherapy also. Karyotypes from 2 of these patients, 1 with 46,XY,20q-, and another with 46,XY,11q-,13q- were examined with G and/or Q banding. From the results of the banding analysis, it appears that the abnormal chromosomes were due to simple deletions at specific sites on their arms, particularly in the cases with the F abnormality (20q11). The breaks occurred in the regions C11q and D12q. The portions missing from the original chromosomes could not be found on any chromosome. Most patients with PV do not develop chromosomal abnormalities through the course of their disease; when such abnormalities appear (20q- in particular), they seem to result exclusively from radiation (and possibly chemo-) therapy. Thus, cytogenetic changes do not appear to play a crucial role in the genesis of PV.

Cytogenetic studies in 12 patients with itai-itai disease

Among 12 Itai-Itai disease patients examined, 8 patients showed a remarkably high frequency of chromatid aberrations, whereas the other 4 patients showed a much lower frequency of such aberrations, although a significant number of stable type aberrations was observed also in the latter patients. The frequencies of aneuploid cells of all 12 patients were significantly higher than those of the controls. The abnormalities were found in 50-hour and 72-hour cultures, from which it can be concluded that the aberrations occurred in the blood stem cell of the patients. In addition to these structural and numerical aberrations, satellite associations of the D and G group chromosomes were often observed.