Development of a versatile high-throughput mutagenesis assay with multiplexed short read NGS using DNA-barcoded supF shuttle vector library amplified in non-SOS E. coli

A forward mutagenesis assay using the supF gene has been widely employed for the last several decades in studies addressing mutation frequencies and mutation spectra associated with various intrinsic and environmental mutagens. In this study, by using a supF shuttle vector and non-SOS-induced Escherichia coli with short-read next-generation sequencing (NGS) technology, we present an advanced method for the study of mutations, which is simple, versatile, and cost-effective. We demonstrate the performance of our newly developed assay via pilot experiments with ultraviolet (UV) irradiation, the results from which emerge more relevant than expected. The NGS data obtained from samples of the indicator E. coli grown on titer plates provides mutation frequency and spectrum data, and uncovers obscure mutations that cannot be detected by a conventional supF assay. Furthermore, a very small amount of NGS data from selection plates reveals the almost full spectrum of mutations in each specimen and offers us a novel insight into the mechanisms of mutagenesis, despite them being considered already well known. We believe that the method presented here will contribute to future opportunities for research on mutagenesis, DNA repair, and cancer.

Human muscle protein degradation in vitro by eosinophil cationic protein (ECP)

To clarify the role of tissue eosinophils in and around inflammatory foci, we purified eosinophil cationic protein (ECP) and examined its effect on muscle protein degradation in vitro. Eosinophil cationic protein was purified from the buffy coat of blood from healthy volunteers. Myofibrillar, soluble sarcoplasmic, and membrane-associated cytoskeletal proteins were fractionated from latissimus dorsi muscle obtained by orthopedic procedures done on a patient with no neurologic abnormalities. After incubation of these fractions with purified ECP, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting were performed. Eosinophil cationic protein degraded the myofibrillar proteins, especially the myosin heavy chain (MHC) and alpha-actinin. It also degraded membrane-associated cytoskeletal proteins dystrophin and spectrin, whereas soluble sarcoplasmic proteins did not undergo proteolysis. Quantitative analysis of the MHC degradation showed that the ECP reaction was dose-dependent and that the optimal pH was 7.0. Protein degradation was not inhibited by heparin or the protease inhibitors leupeptin, E-64, and pepstatin A. Our results suggest that ECP functions in the degradation of myofibrillar and membrane-associated cytoskeletal proteins, indicating that tissue eosinophils have a specific role in muscle fiber degradation in some myopathies associated with numerous tissue eosinophils, such as eosinophilic myositis, eosinophilic myalgia syndrome, and eosinophilic endocardial disease.

[A case of neuro-Behçet's disease presenting with chorea]

A 46-year-old man was admitted to our hospital because of emotional instability and involuntary movement of the right upper limb. Neurological examination revealed inability to concentrate, emotional incontinence, recent memory disturbance, chorea of bilateral upper limbs and neck, and bilateral pyramidal signs. Brain MRI showed atrophy of bilateral caudate nucleus and diffuse abnormal intensity area with low intensity on T1-weighted images and high intensity on T2-weighted images in cerebral white matter around the lateral ventricles. Huntington's disease was suspected at first, but it was ruled out by DNA analysis. After admission, oral and genital aphthae developed and the CSF examination showed pleocytosis (273 leukocytes/mm3; 39 polymorphonuclear leukocytes and 234 lymphocytes), so we diagnosed this case as neuro-Behçet's disease. Although basal ganglia is occasionally involved in neuro-Behçet's disease, chorea is rare. Neuro-Behçet's disease should be considered as a cause of chorea.

Production of an immunosuppressive polysaccharide, AZ9, in the culture of Klebsiella oxytoca strain TNM3

A soil bacterium, Klebsiella oxytoca TNM3, was found to produce a polysaccharide named AZ9 with immunosuppressive activities. The culture of K. oxytoca in a jar fermentor resulted in an extreme increase in the viscosity of the culture broth (>10,000 mPa.s) due to accumulation of the polysaccharide with a high molecular weight. The molecular weight of AZ9 was successfully controlled by supplementing ethylenediamine tetraacetic acid (EDTA) and Fe2+ ion to the culture. Under optimized culture conditions, 39 g/l AZ9 with an average molecular weight of 200 kDa was produced, which was effective in suppressing IgE antibody production in mice.

Prevention of collagen-induced arthritis in DBA/1 mice by oral administration of AZ-9, a bacterial polysaccharide from Klebsiella oxytoca

Collagen-induced arthritis (CIA) is an excellent model of rheumatoid arthritis (RA) in humans that is induced in DBA/1 mice immunized with bovine type II collagen (CII). Here, we report that the induction of CIA was effectively suppressed by oral administration of AZ-9, a purified polysaccharide with the average molecular weight of approximately 200 kDa that was produced by a soil bacterium, Klebsiella oxytoca. When AZ-9 was administered at 125-250 mg/kg/day orally for 9 consecutive days after immunization with CII followed by its administration every 3 days, resulted in a marked reduction of the incidence and the severity of CIA. The serum level of anti-CII IgG2a and the production of IFN-gamma and IL-12 in the draining lymph node (LN) cells were significantly lower in AZ-9-administered mice than the untreated control. These findings suggest that orally administered AZ-9 suppressed CIA through attenuating a Th1-type response to CII. AZ-9 could be fragmented into smaller molecules (3-4 kDa) without losing its suppressive activity.

A novel mutation of the McLeod syndrome gene in a Japanese family

McLeod syndrome is a rare X-linked hematologic and neuromuscular disorder manifested by chorea, myopathy, cardiomyopathy, areflexia, hyperCKemia, and acanthocytosis. Only four mutations have been reported in the gene responsible for McLeod syndrome. We report a novel gene mutation in a Japanese family. Direct sequencing of the PCR-amplified genomic DNA revealed the mutation was a single C-nucleotide insertion at codon 151 in exon 2 of the XK gene, which resulted in a 3'-frameshift. Study of family members revealed that the patient's mother was a manifesting carrier heterozygous for this mutation.

[A case of McLeod syndrome]

A 52-year-old man was admitted to our hospital in 1997 because of high serum creatine kinase (CK) level. Neurologic findings revealed chorea on the trunk and extremities, mild weakness of proximal muscles, and absence of deep tendon reflexes in four extremities. Serum CK was elevated to 3,494 U/l (normal, below 235). A peripheral blood smear showed acanthocytes in approximately 1% of the red blood cells (RBCs). Very weak expression of the Kell antigens (K2, K4, K5, and K7) on his RBCs led us to make a final diagnosis of McLeod syndrome. Muscle biopsy from the left biceps showed increased variability in fiber diameter, a few regenerating fibers, scattered fibers with internal nuclei, and mild fiber type grouping. Immunohistochemical analyses of dystrophin. merosin, and adhalin were normal. Although McLeod syndrome is a rare X-linked recessive disorder, it is clinically important for differential diagnosis of chorea acanthocytosis and hyperCKemia.

Proteasomes in distal myopathy with rimmed vacuoles

In a previous report we suggested that muscle fibers in distal myopathy with rimmed vacuoles (DMRV) were degraded by both lysosomal proteolysis (cathepsins) and Ca2+-dependent, nonlysosomal proteolysis (calpain). Given recent evidence of abnormal ubiquitin accumulation in rimmed vacuoles, we examined the role of the ATP-ubiquitin-dependent proteolytic pathway (proteasomes) in myofiber degradation in this myopathy. Immunohistochemically, proteasomes (26S) were located in the cytoplasm in normal human muscle, but the staining intensity was weak. Quantitative analysis showed more reactivity for proteasomes in DMRV muscles and, to a lesser extent, in muscles from muscular dystrophy, polymyositis, and amyotrophic lateral sclerosis patients. In DMRV, proteasomes often were located within or on the rim of rimmed vacuoles, and in the cytoplasm of atrophic fibers. Ubiquitin accumulation was marked within rimmed vacuoles and was seen less extensively in the cytoplasm of atrophic fibers. The latter proteins colocalized well. In other diseased muscles, proteasomes and ubiquitin showed a positive reaction in the atrophic or necrotic fibers. The results indicate increased proteasome and ubiquitin in these muscle fibers as well as in other diseased muscle fibers. We suggest that the ATP-ubiquitin-proteasome proteolytic pathway as well as the nonlysosomal calpain and the lysosomal proteolytic pathway may participate in the muscle fiber degradation in DMRV.

Effect of chloroquine-induced myopathy on rat soleus muscle sarcoplasm and expression of clathrin

Clathrin-coated vesicles are involved in receptor-mediated intracellular transport pathways related to lysosomal proteolysis. Clathrin levels were significantly elevated in denervated soleus muscles from chloroquine- and saline-treated rats as compared with their contralateral, innervated muscles. No difference was found in the clathrin levels of the denervated muscles in both groups. The accumulation of autophagic vacuoles was marked only in chloroquine-treated muscles after denervation. These findings suggest that chloroquine does not inhibit intracellular trafficking of clathrin-coated vesicles during the overdevelopment of autophagic vacuoles.

[A case report of Bickerstaff brainstem encephalitis with attention to electronystagmographic findings]

We evaluated brainstem function by using electronystagmography in a 43-year-old woman with typical Bickerstaff brainstem encephalitis. She developed fever, drowsiness, total opthalmoplegia, swallowing disturbance, areflexia, and muscle weakness. On electronystagmography, eye-tracking test showed ataxic pattern with impaired smooth pursuit eye movement. The horizontal optokinetic nystagmus test showed diminished pattern. Caloric test revealed the vestibular hypofunction and the increase of caloric nystagmus on eye fixation. We considered these findings were attributed to the disturbance of pontine tegmentum, especially reticular formation. These findings were similar to those observed in patients with Fisher syndrome.

Calpain and cathepsins in the skeletal muscle of inflammatory myopathies

To clarify the significance of intracellular lysosomal (cathepsins B, L and H) and extralysosomal (calpain) proteolytic systems in the process of muscle fiber degradation in inflammatory myopathies, biopsied muscle specimens were examined from patients with polymyositis (PM) and dermatomyositis (DM). Generally, in specimens from patients with PM and DM, but not in those from normal controls, muscle fibers surrounding inflammatory infiltrates or in the perifascicular regions, and occasionally mononuclear cell infiltrates demonstrated positive immunostaining for calpain and cathepsins B, L, and H. In addition, enzyme activities of cathepsins B and L increased in specimens with inflammatory myopathy. These results suggest that calpain and cathepsins play a significant role in the process of muscle fiber destruction in inflammatory myopathy.

Elevated soluble intercellular adhesion molecules-1 in inflammatory myopathy

INTRODUCTION

We evaluated the serum level of soluble intercellular adhesion molecule-1 (sICAM-1) in patients with polymyositis (PM) and dermatomyositis (DM) and investigated the correlation between the serum level of sICAM-1 and clinical findings.

MATERIAL AND METHODS

We measured the serum level of sICAM-1 using an enzyme-linked immunosorbent assay in 19 untreated patients with inflammatory myopathy (14 patients with PM and 5 patients with DM), 20 patients with other neuromuscular disorders in which immunological mechanisms are unlikely to be involved, and 14 normal healthy controls.

RESULTS

The serum level of sICAM-1 was significantly higher in patients with PM/DM compared with patients with other neurological disorders and control subjects. The sICAM-1 level was, however, not correlated with the clinical characteristic including disease severity, the duration of illness, and the serum level of CK.

CONCLUSION

These findings suggest that sICAM-1 is involved in the inflammatory process of PM and DM.

[Pharmacokinetics of transbronchially injected flconazole in pulmonary aspergillosis]

A 68-year-old woman had a pulmonary aspergilloma in the left upper lobe, with old cavitary pulmonary tuberculosis. Surgery was not possible because of marginal ventilation, and the patient was treated by transbronchial injection of Fulconazole. After five injections of 50 mg of Fulconazole, the fungus ball had decreased in size. To study the pharmacokinetics of Fulconazole after transbronchial injection, its concentration in serum was measured. The values of serum Fulconazole concentration were 0.7 microgram/ml at 1 h, 0.8 microgram/ml at 4 h, 0.8 microgram/ml at 8 h, 0.7 microgram/ml at 12 h, 0.7 microgram/ml at 24 h, and 0 microgram/ml at 48 h after transbronchial injection. These results indicate that Fulconazole was absorbed well. Furthermore, these values are equal to those obtained after intravenous administration of 50 mg and are higher than those obtained after intravenous administration of 25 mg. Fulconazole may have been absorbed via the bronchial epithelium, because of destruction of alveoli, connective tissue proliferation in the cavitary wall and secondary bronchiectasis.

The effect of TYB-2285 on dual phase bronchoconstriction and airway hypersensitivity in guinea-pigs actively sensitized with ovalbumin

The effect of a new anti-asthmatic drug, TYB-2285 (3,5-bis(acetoxyacetylamino)-4-chlorobenzonitrile), was investigated in ovalbumin-sensitized guinea-pigs. When guinea-pigs were pretreated with TYB-2285 (300 mg kg-1, p.o., single dose or consecutively for 7 days), the immediate asthmatic response was inhibited as demonstrated by diminished cyanosis, but not the bronchoconstriction. TYB-2285, given singly or consecutively, inhibited the appearance of late asthmatic response and the infiltration of inflammatory cells, such as eosinophils, into the airway. Additionally, airway hyper-responsiveness was also reversed by the single administration of TYB-2285. Luminol-dependent chemiluminescence of airway-infiltrated cells stimulated with A23187 was inhibited by TYB-2285 in a dose-dependent manner. The present study suggests that TYB-2285 inhibits late asthmatic response and airway hyperresponsiveness by inhibiting the accumulation of eosinophils and other inflammatory cells into the airway, and also by inhibiting the production of oxygen radicals from airway-infiltrated cells.

[A case of facioscapulohumeral muscular atrophy presenting unusual squatting gait, associated with tongue atrophy and sensorineural hearing loss]

A 16-year-old girl has presented speaking disturbance since early in life. Difficulty in running was noted at the age of 7. Her mother (46 years old) had moderate facial weakness and mild proximal weakness of the upper and lower limbs. Neurological examination at age 9 revealed bilateral facial weakness, tongue atrophy and weakness of the shoulder girdle, upper arms, and thighs. Deep tendon reflexes were absent in the four limbs. Gait was waddling. Over the next several years, she developed wasting and weakness around the shoulder girdle, upper arms, thighs, and increased lordosis. She lost the ability to walk by age 13. Since then, she has moved with difficulty in a squatting position. Serum CK was moderately increased and needle EMG in the extremities revealed myopathic changes. Muscle CT demonstrated marked atrophy of the proximal muscles in the left arm and lower limbs and mild atrophy of the calves. Audiogram showed bilateral mild sensorineural hearing loss. Muscle biopsy of the quadriceps at age 9 showed nondiagnostic findings. This case could be diagnosed as congenital facioscapulohumeral muscular dystrophy. Tongue atrophy and sensorineural hearing loss are rarely associated with this syndrome, as well as unusual squatting gait.

[A case of Crow-Fukase syndrome which developed seven years following myelopathy of unknown origin]

A rare case of Crow-Fukase syndrome was reported, which developed 7 years following myelopathy of unknown origin. In September 1983, a 31-year-old man came to our department for progressive gait disturbance and numbness in both lower extremities. Examination on admission showed hyperreflexia with clonus and moderated muscle weakness of legs, and paresthesia below Th9 level, but myelography and CT indicated no abnormality. Thereafter, he was doing as well as walkable with a cane, but in 1989 he developed hypertrichosis, skin pigmentation, leg edema and gynecomastia with aggravation of numbness of lower extremity and was rehospitalized in October. Detailed examination on the present admission indicated compression of the conus medullaris due to an osteosclerotic lesion of vertebral body L1, which did not correspond to the possible site of pyramidal sign. Thus, the origin of the myelopathy remained unknown. After hospitalization, polyneuropathy newly developed, making him confined to his bed. Thus, the diagnosis was established as Crow-Fukase syndrome. Subtotal extirpation of L1 vertebral body and steroid therapy (PSL 10 mg/day) caused improvements of polyneuropathy and numbness of lower extremity, making him walkable again and return to his social work 3 months later. Pathohistological examination of the osteosclerotic lesion proved partial plasmacytoma. In MRI findings of the osteosclerotic lesion, the osteosclerotic and plasmacytomatous regions were outlined as low and high signals, respectively for both T1 and T2-weighted. MRI examination was very useful for grasping the tumorous extent within the osteosclerotic lesion as observed with Crow-Fukase syndrome and for determining the extent of indication for surgery and radiotherapy.

[An autopsy case of neoplastic angioendotheliosis mainly affecting the lung and presenting with atypical cells in peripheral blood]

Neoplastic angioendotheliosis (NAE) is a rare condition characterized by proliferation of atypical cells in small vessels of various organs. In the past, atypical cells seen in this condition were considered to originate from vascular endothelial cells. However, recent immunohistochemical studies have established that the tumor cells in this condition mainly originate from B-lymphocytes. NAE is likely to affect the central nervous system and skin. Cases of NAE with a primary lesion in the pulmonary vessels are rare. One such rare case of NAE was recently encountered by us. The patient was a 77-year-old woman who was admitted to our department because of fever and interstitial shadow in both lungs. After admission, fever did not subside, and the pulmonary shadow became more marked. Laboratory tests upon admission disclosed elevated LDH. Of isozymes, LDH2 and LDH3 were high. Anemia and thrombocytopenia gradually became aggravated, and atypical cells with large basophilic cell body and irregularly shaped nucleus subsequently appeared in peripheral blood. Thereafter, the patient's general condition worsened rapidly and she died about 5 months after admission. Post-mortem examination revealed pleomorphic atypical cells filling the lumen of small vessels in various regions of the body. This finding was particularly marked in pulmonary vessels. With various immunohistochemical stains, these cells were identified as cells of B-lymphocyte origin.

[Study of prognostic factors of survival in patients with unresectable non-small cell lung cancer]

We studied prognostic factors of survival in 121 patients unresectable non-small cell lung cancer treated between March 1983 and November 1988 at forth department of internal medicine, Kinki university school of medicine, about histology, clinical stage, age, sex, performance status, Brinkman Index, hemoglobin, serum TP, serum Alb, serum LDH, pulmonary function and chemotherapy. The prognostic factors were studied using survival rate by Kaplan-Meier method, univariate analysis by Log-rank test and generalized Wilcoxon test and multivariate analysis by proportional hazard model of Cox. The prognostic factors of pretreatment were age, serum Alb, serum LDH, pulmonary dysfunction of mixed type and performance status. In the classified study according to histology, age and pulmonary dysfunction of mixed type were prognostic importance in patients with squamous cell lung cancer. Hemoglobin in patients with squamous cell lung cancer was important, too. The chemotherapy given good response improved patient's prognosis.

[A case of multiple inflammatory tracheo-bronchial polyps associated with chronic sinusitis]

A 57 year-old woman was aware of breath odor and visited to our hospital. There were no abnormal findings in her physical examination and chest X-ray. Multiple polyps in the trachea and both main bronchi were discovered by fiberoptic bronchoscopy. They were 0.1-0.5 cm in diameter. In a histological examination, squamous metaplastic epithelial cells and numerous inflammatory cells infiltrating subepithelially were seen. No malignant cells were found. The patient had suffered from chronic sinusitis for 15 years, and it was suggested that the development of tracheo-bronchial polyps was associated with chronic sinusitis.

[The inhibitory effect of oxatomide, an anti-allergic agent, on eosinophil-mediated and eosinophilic cell line-mediated natural cytotoxicity against bronchial epithelial cells]

Recently, eosinophils have been implicated as inflammatory effector cells in allergic and inflammatory reactions such as bronchial asthma. In this study eosinophil-mediated and eosinophilic cell line-mediated natural cytotoxicity against bronchial epithelial cells and the effects of oxatomide, an anti-allergic agent, on their cytotoxicity were investigated. Treatment with oxatomide diminished both eosinophil-mediated and eosinophilic cell line-mediated natural cytotoxicity in vitro. We concluded from these results that oxatomide not only has anti-allergic activity but also anti-inflammatory properties for eosinophils. In addition this method for isolating eosinophils seems to well serve the purpose of evaluating eosinophil function as in this investigation, as we have reported previously.

[IgE-Fc receptor expressions on bronchoalveolar lavage (BAL) cells in a patient with eosinophilic pneumonia accompanied with bronchial asthma--the effect of ketotifen on their expression]

In this study, IgE-Fc receptor expressions on each type of BAL cells (lymphocytes, macrophages and eosinophils) in a patients with eosinophilic pneumonia accompanied by bronchial asthma were examined by indirect immunofluorescent method using monoclonal antibody (H107). BAL cell findings showed marked increases of total BAL cell counts and eosinophils, an increased number of lymphocytes and the presence of basophilic cells. These results match those of our previous report. Furthermore, IgE-Fc receptor expressions on lymphocytes, macrophages and eosinophils were markedly increased as compared to those in the peripheral blood and normal control subjects. These findings suggest that IgE production in the lung plays the main role in the pathogenesis of eosinophilic pneumonia and bronchial asthma. On the other hand, during ketotifen administration, decreases of peripheral blood eosinophilia, of eosinophilia in the sputum and of serum IgE level and an improvement in chest X-ray findings were observed. Furthermore not only normalization of total BAL cell counts but also decreases of IgE-Fc receptor expressions on BAL cells were observed.

Comparison of several methods for the measurement of urinary hippuric acid as an index of toluene exposure

The levels of hippuric acid in the urine of people exposed to toluene vapour were measured by paper chromatography, direct colorimetry, high performance liquid chromatography and gas chromatography. The control was a similar group not exposed to toluene vapour. The values were analyzed statistically, conversion equations calculated, and the propriety of these equation discussed. Since the three chromatographic methods gave similar values, the measurement of urinary hippuric acid by these methods can be used as an index of toluene exposure. The colorimetric method gave higher levels the chromatographic methods, especially for the urine of people not exposed to toluene. This may have been due to glycine conjugates (other than hippuric acid) developing a similar color, resulting in elevated values for hippuric acid. This colorimetric method should be used with caution for biological evaluation of workers with low toluene exposure.

An improved direct colorimetric method for the quantitative analysis of urinary hippuric acid as an index of toluene exposure

An improved direct colorimetric method for determining the concentration of urinary hippuric acid as an index of toluene exposure was described. One tenth ml of urine was diluted with 0.4 ml 0.01 M phosphate buffer H 6.9 and mixed with 0.5 ml pyridine. The mixture was layered on 0.2 ml benzenesulfonyl chloride. The reaction was started by mixing for one min with a mechanical shaker. The colored solution was allowed to stand for 30 min, diluted with 5 ml ethanol, and absorbance measured at 410 nm within 30 min after the dilution. The coefficient of variation of this method was 6% and the recovery 103% when urine contains about 0.2-0.5 mg hippuric acid per ml of urine. The concentration was linear up to 2.0 mg per ml hippuric acid in a specimen.

Electron microscopic observations on the morphogenesis of renal cell carcinoma induced in rat kidney by dimethylnitrosamine and N-(3,5-dichlorophenyl)succinimide

Renal cell carcinoma was induced in rats by p.o. administration of dimethylnitrosamine, 500 ppm daily, followed by N-(3,5-dichlorophenyl) succinimide (NDPS), 5000 ppm daily. Fine structural changes of the proximal convoluted tubule cells were observed by sequential examinations of the kidney cortices at 3, 5, 12, and 24 weeks after drug administration. Early prominent structural changes of the cells induced by dimethylnitrosamine alone were the appearance of microspherules in nucleoli and of numerous lamellar bodies on the membrane structure of the cells. With the addition of NDPS, the cells exhibited edematous cytoplasm that, in contrast to the relatively intact nuclear structure, contained numerous bodies small vesicles and dark mitochondria, with markedly disarranged microvilli. After prolonged treatment with these drugs, some of the cells showed regenerating features, while others became necrotic. In the former case, large clear nuclei appeared with enlarged nucleoli containing a large amount of granular components. Ribosomes in the cytoplasm also increased in number in accordance with nucleolar changes, and edema in cytoplasm and microvilli markedly decreased. However, a considerable number of vesicles still remained in some cells. Mitochondria decreased in number and showed pleomorphism and relatively high electron density. At 24 weeks, when clear cell carcinoma was induced, the cells in the cancer tissue exhibited a variety of features in their nuclei and cytoplasm. Some cells showed intact nuclear structure and dark cytoplasm containing a large number of vesicles; others had large round clear nuclei with enlarged nucleoli and clear cytoplasm containing no vesicles. Among these cells were mixed populations of large clear cells, showing a structure similar to the cells at 12 weeks, 2.e., to nodular hyperplastic cells. The starting point of malignant transformation seemed to be 1 week after treatment with NDPS (i.e., cells at 5 weeks) and, or the precancerous stage, at 12 weeks. These results suggest that the proximal convoluted tubule cells previously damaged by dimethylnitrosamine treatment were marked for mutation and were transformed to cancer cells by additional treatment with NDPS in such a way as to disturb the permeability of the membrane system of the cell and to condense chromatin fibers.