[Effects of intra-hepatic arterial injection of mitoxantrone for hepatocellular carcinoma]

Twenty patients with unresectable hepatoma, recurrent hepatoma or metastatic liver cancer were treated by intra-hepatic arterial injection of mitoxantrone, and its effectiveness and side effects were studied. In 35.5% of the patients, complete or partial responses were seen. The survival intervals after the beginning of therapy were from one to 21 months (mean, 9.4 months) and one-year survival ratio was 56.3%. Red blood cell, leukocyte, and platelet counts diminished significantly one week later after administration of mitoxantrone compared with the pre-administration levels. Severe hepatic dysfunction has not been experienced.

A nitric oxide donor reverses myocardial injury in rabbits with acute hypercholesterolemia

We evaluated the propagation of myocardial injury in a model of coronary artery occlusion and reperfusion in control and hypercholesterolemic rabbits. This was done by examining the differences in the infarct size and in the extent of leukocyte accumulation resulting from coronary artery occlusion (30 min) followed by reperfusion (2 or 48 hr) in rabbits fed 1% cholesterol for 4 days vs. controls not fed cholesterol. There was no significant difference in the infarct size in the 2-hr (45.7 +/- 6.7%, n = 8) vs. 48-hr (48.8 +/- 5.8%, n = 9) models of reperfusion in control rabbits. However, infarct size in the cholesterol-fed rabbits at 2 hr (64.0 +/- 4.1%, n = 6) or 48 hr (72.3 +/- 3.0%, n = 8) of reperfusion significantly exceeded that in the corresponding controls (P < .05). The infarct in cholesterol-fed rabbits at 2 hr of reperfusion was smaller than that at 48 hr of reperfusion, but not significantly. Treatment with S-nitroso-N-acetylpenicillamine, a nitric oxide donor, effectively reduced the size of infarct in the cholesterol-fed rabbits. However, treatment with N-acetylpenicillamine had no infarct-limiting effect. When we evaluated the extent of leukocyte accumulation in the ischemic myocardium, as assessed by myeloperoxidase activity, a positive correlation was observed between myeloperoxidase activity and infarct size at 48 hr of reperfusion. Results indicate that the propagation of myocardial ischemia and reperfusion injury in acutely hypercholesterolemic rabbits differed from that in controls. An exogenous nitric oxide donor effectively reduced the size of infarct associated with the reduction in the accumulation of leukocytes 48 hr after reperfusion, which suggests that a reduction in the production of endogenous nitric oxide during ischemia and reperfusion may aggravate the severity of myocardial injury in acutely hypercholesterolemic rabbits.

Anti-erythropoietin receptor monoclonal antibody: epitope mapping, quantification of the soluble receptor, and detection of the solubilized transmembrane receptor and the receptor-expressing cells

A hybridoma cell line producing the monoclonal antibody against erythropoietin receptor (EpoR) was established using the soluble ectodomain of mouse erythropoietin receptor (sEpoR) as an antigen. The monoclonal antibody termed 1G3 bound to the denatured sEpoR. Epitope mapping with peptide library revealed that 1G3 recognized the amino terminal region including the hexapeptide (positions 6 to 11; LeuProAspProLysPhe). The amino acid sequence in this hexapeptide was identical in mice, rats, and humans, and therefore 1G3 bound to EpoR from all of these sources. Using 1G3, we evaluated sEpoR by a sandwich enzyme-linked immunoassay, and EpoR in the solubilized membrane preparation was detected by Western blotting. The cells expressing EpoR were identified with immunochemical staining. We confirmed the presence of EpoR in a neuronal cell line and PC12 cells, and EpoR was expressed in primary cultured hippocampal neurons.

[A case of bilateral pneumothorax in the patient with Marfan syndrome]

A case of bilateral pneumothorax in the patient with Marfan Syndrome was reported 13-year-old male was admitted to our hospital with diagnosis of left pneumothorax. He was tall and thin with long tapered extremities and echography revealed annulo-aortic-ectasia. A diagnosis of Marfan Syndrome was established by these characteristic of skeletal and cardiovascular findings. Air leakage continued inspite of the drainage of left chest cavity. Therefore, the resection of bullae was surgically undertaken. Post-operative course was uneventful and he discharged on 18th post-operative day. The pneumothorax of the right side occurred six months after first operation. After chest drainage, the surgical treatment was performed. However, he had recurrence of right pneumothorax six months after second operation. He was treated successfully with drainage tube and minocycline injection into the right pleural cavity. He should be carefully followed up, because the patient of Marfan Syndrome often dies due to cardiovascular abnormalities.

[An immunohistological study on expression of glutathione S-transferase pi (form) in dysplastic and neoplastic human uterine cervix lesions]

The glutathione S-transferase (GST) pi has been studied in association with the mechanisms of multidrug resistance and as a marker for malignant tumors. In this study, specimens from 92 cases of cervical neoplasms and 10 cases of normal squamous epithelium adhering to myoma were stained immunohistochemically with a rabbit polyclonal antibody to GST-pi. In 6 cases of normal squamous epithelium, the intermediate layer was positively stained with the GST-pi antibody. In all 20 cases of dysplasia, the cells with koilocytotic atypia were stained positively. In all 10 cases of carcinoma in situ and all 16 cases of stage Ia squamous cell carcinoma, various intensities of GST-pi staining were demonstrated. Forty-six specimens of stage Ib or more squamous cell carcinoma were positive for GST-pi binding except only one case. In general, squamous cell carcinoma of the uterine cervix is resistant to chemotherapeutic agents. GST-pi is most frequently stained in cervical squamous cell carcinoma as compared with ovarian or endometrial carcinoma. In conclusion, these results suggest that GST-pi may be a marker for cervical squamous cell carcinoma.

[Usefulness of reaction times in high-cortical recognition tasks]

We compared reaction times for high-cortical recognition tasks with kana-searching test in a group of 46 normal individuals aged 21 to 83 who gain a full score in Mini-Mental State. The following tasks of reaction time were used; simple reaction time (SRT), choice reaction time (CRT), memory scanning time (MST), and visual searching time (VST). The results were consistent and demonstrated that mean reaction time of 46 individuals increased in difficult tasks such as MST or VST. All reaction times increased depending on aging, which became longer in difficult tasks. Score of kana-searching test was correlated with MST and VST, but did not correlate with SRT and CRT. These findings suggest that reaction times may be useful for mass-screening of high-cortical functions in different ages as well as the kana-searching test.

Site-directed mutagenesis of hamster complement C1S: characterization with an active form-specific antibody and possible involvement of C1S in tumorigenicity

We have previously shown that non-transformed mouse A31 cells became tumorigenic when they were transfected with hamster C1s cDNA expression plasmid BCMGSNeoCS. In the present study, mutations were introduced into the cDNA at the activation cleavage site, Arg423(AGG) and the active center Ser617(AGC). These amino-acids were replaced by His423(CAC) and Thr617(ACC), respectively. The mutated cDNAs were inserted into BCMGSNeo and transfected to A31 and its polyoma-virus-transformed SEA7 cells. C1s produced from these transfectants lost their enzyme activity. Transfectants of these mutated C1s cDNA did not form tumors in nude mice, To distinguish between active and inactive C1s in situ, we have developed novel antibodies, one directed to the NH2-terminal neoepitope of the L chain and the other specific for uncleaved inactive C1s. These antibodies were used to characterize C1s produced by transfectants, so as to determine whether or not it was cleaved at the right position.

A novel nonsense mutation associated with an exon skipping in a patient with hereditary protein S deficiency type I

The genetic defect in a patient with hereditary type I protein S (PS) deficiency was investigated. All the exons and intron-exon junctions of the patient's PS gene were amplified by PCR and subjected to heteroduplex screening. Only the PCR product of exon 4 revealed heteroduplex bands. A novel nonsense mutation, Ser62 (TCA) to Stop (TGA) was found in exon 4. RT-PCR detected the aberrant mRNA in the patient's platelets, which was markedly reduced in amount and lacked the region of exon 4, suggesting that the nonsense mutation affected the mutated mRNA metabolism and induced exon skipping. The skipping of exon 4 causes an in-frame deletion of 29 amino acids which just construct the thrombin-sensitive region of the PS molecule. The loss of such an important domain as well as the quantitative decrease in the mutated mRNA appear to be responsible for the type I PS deficiency in this patient.

Establishment of eighteen clones of Ishikawa cells

Ishikawa cells, which derive from a well differentiated human endometrial adenocarcinoma, were cloned using the limiting dilution method in an attempt to preserve well differentiated cells. Eighteen clones were obtained. According to their morphologic characteristics, there were six well differentiated, seven moderately differentiated, three poorly differentiated and two adenosquamous carcinoma clones. All of them were transplantable into node mice. Fifteen of the 17 clones were positive for estrogen receptors and all of the clones examined were positive for progesterone receptors. There were no significant differences in terms of population doubling time, plating efficiency or saturation density among these clones. On the basis of these results, we concluded that Ishikawa cells are not as homogeneous morphologically as we thought, since cells with varying degrees of differentiation have already mingled with the parent cell line. It is verified that the adenosquamous cell carcinoma of the endometrium can arise from one stem cell. It would be impossible to revive the cultured cells after having undergone their changes to the original conditions. Therefore, to preserve the characteristics of an established cell line, the cells should be frozen at a very early stage. It is also important to avoid frequent passages when special characters of the cells are necessary for a given investigation.

MRI evidence of high signal intensity and temporomandibular arthralgia and relating pain. Does the high signal correlate to the pain?

In order to investigate the relationship between various temporomandibular joint (TMJ) pain levels and the detection of high signal intensity (joint effusion) on T2 weighted magnetic resonance imaging (MRI), 19 consecutive patients who complained of unilateral painful TMJ hypomobility (closed locking) were involved in this study. All patients were clinically examined in a routine manner, and all patients rated their pain levels by a visual analogue scale and eight pain questionnaire prior MRI study. T1 and T2 weighted MRI was taken in sagittal section at unilateral affected joint side. The presence or absence of a high signal intensity spot within the TMJ compartment were judged by three examiners. The high signal intensity was detected in 10 joints, but not in 9 joints. In between these two groups, the pain ratio was calculated and compared. The data showed that there was no significant statistical correlation between pain levels and the presence of high signals. This study disclosed that the MRI detection of high signal intensity in the closed locking TMJ did not directly relate to the presence of TMJ pain nor the increased pain level. These indicate the need of further larger studies.

[Drug-resistance patterns of clinical isolates of Pseudomonas aeruginosa in regard to their lipopolysaccharide-chain sizes]

Pseudomonas aeruginosa strains isolated from patients with different types of the infections each consisted of LPSs different in chain sizes. The drug-susceptibility patterns of these strains of P. aeruginosa were investigated to clarify the relationship between the LPS-compositions and susceptibility to some kinds of anti-pseudomonal drugs. The susceptibilities of nineteen strains (seven long-LPS strains, four short-LPS strains and eight LPS-deficient strains) to piperacillin, ceftazidime, gentamicin, norfloxacin and polymyxin-B were determined and these strains were classified into six types (Types I-VI) according to their drug-resistance patterns. Six of the eight LPS-deficient strains were found to be highly resistant to gentamicin alone (Type IV). Four of the seven strains with the long-LPS and one strain with the short-LPS were resistant to three drugs such as piperacillin, ceftazidime and norfloxacin, and classified into Type I. These results indicated that the major part of the LPS-deficient strains and the considerable part of the long-chain LPS strains of P. aeruginosa tested had each characteristic profile in the drug resistance. The outer membrane proteins of thirteen strains, consisting of different types of LPS compositions, were analyzed by SDS-PAGE. The strains belonging to the same types of the drug-resistance patterns were found to have similar OMP-profiles, although a few exceptions were found. beta-lactamase and gentamicin-inactivating activities were determined for piperacillin-resistant and gentamicin-resistant strains, respectively. Of the piperacillin-resistant strains tested, the activity of beta-lactamase was high in one (No. 8) only, low in four and not found in four. The results showed that degrees of resistance of P. aeruginosa strains tested to piperacillin did not correlate to their producibility of beta-lactamase except one strain. Of the nine gentamicin-resistant strains tested, the gentamicin inactivating activity was high in one (No. 30) only, moderate in six and low in two. These results suggested that the significant levels of piperacillin- or gentamicin-resistance of P. aeruginosa isolated tested might be expressed each due to their decreased abilities for drug-permeabilities in addition to drug-inactivating activities such as beta-lactamase or gentamicin-modifying enzyme. In the case of some resistant strains, the resistance to piperacillin or gentamicin was not explained by the results of the present study. Therefore, we must investigate the possibility that other mechanisms participate in the resistance of these strains.

MR staging of pelvic endometriosis: role of fat-suppression T1-weighted images

We examined whether MR can determine the stage of endometriosis according to the scoring system established and revised by the American Fertility Society (r-AFS), a system which is widely used by gynecologists. We also studied the utility of fat suppression T1-weighted images in improving accuracy. Seventeen patients with endometriosis examined by conventional MR were included in this study. All the patients had surgically proved stage III or IV disease. We determined the stage by MR using the following criteria according to the r-AFS system: adnexal masses without normal ovarian tissue were considered deep ovarian lesions, while those with normal tissue were considered superficial. A lack of fat between the lesion and surrounding structures was considered a dense adhesion, and hyperintense spots were considered peritoneal implants. The MR scores of patients with and without fat suppression were correlated with the surgical scores. MR staging corresponded to surgical staging in 15 of the 17 patients. In eight patients, peritoneal implants of less than 1.5 cm were depicted only by fat-suppression images. However, these lesions did not change the score significantly. MR imaging could determine the stage in advanced endometriosis. Fat-suppression could highlight smaller implants. These tiny lesions had little clinical meaning in these advanced cases; however, the clinical value of this technique should be evaluated in milder disease.

[Drug-resistance patterns and biological properties of MRSA isolated from different geographical areas of Japan]

One hundred isolates of methicillin-resistant Staphylococcus aureus (MRSA) collected from hospitals located in different geographical areas of Japan were used in the present study. The susceptibilities of the strains to gentamicin (GM), erythromycin (EM), tetracycline (TC) and ofloxacin (OFLX) were determined and classified into twelve groups according to their differences in the patterns of the resistance to the four drugs. Of the 100 strains tested, 75 belonging to the main four groups were investigated for the relationships between their patterns of the drug-resistance and biological properties such as coagulase, enterotoxin and phage types, TSST-1 and beta-lactamase producibilities, and percentages of the strains carrying plasmids of large size (> or = 20,000 bp). The main four patterns of drug resistance of the 75 strains were as follows: the first group (33 strains resistant to GM, EM, TC and OFLX), the second group (15 strains resistant to EM, TC and OFLX), the third group (11 strains resistant to GM, EM and OFLX) and the fourth group (16 strains resistant to EM and OFLX) and the remaining 25 strains were divided into further groups. A considerable number of the strains in the third group differed markedly in some biological properties from those in the other groups; coagulase typing (III type-50%: the other groups-II type), enterotoxin typing (64%-non-production: the other groups-C type), TSST-1 producibility (36%-production: the other groups-76 to 88%-production) and phage typing (55%-non-typable: the other groups-80 to 97%-non-typable). In beta-lactamase and plasmids of large size, the first group consisted of the strains with beta-lactamase producibility at the ratio of 50:50, but the other groups consisted of most of the strains with the beta-lactamase producibility. Most of the strains belonging to the second and fourth groups carried large size of plasmids, but 36 and 46% of those belonging to the first and third groups did not carry them. On the other hand, our results of the susceptibility test for the 100 strains showed that a considerable number of strains were susceptible to GM (35%) and TC (42%) at therapeutically significant concentrations.

Amelioration of severity of myocardial injury by a nitric oxide donor in rabbits fed a cholesterol-rich diet

OBJECTIVES

This study compared the effect of a nitric oxide donor on limiting the size of infarct resulting from myocardial ischemia-reperfusion between atherosclerotic and nonatherosclerotic models.

BACKGROUND

Endothelial-derived relaxation in coronary arteries affected by ischemia is substantially impaired after reperfusion, and this impairment may exacerbate the myocardial ischemia-reperfusion injury. In animals with experimental atherosclerosis, release of endothelial-derived relaxing factor is also decreased, and the propagation of myocardial infarction could be exacerbated.

METHODS

We examined the extent of myocardial injury induced by ischemia (30 min) and reperfusion (48 hr) in rabbits fed a cholesterol-rich (1%) or normal diet for 10 weeks. We also evaluated the effect of a nitric oxide donor (S-nitroso-N-acetylpenicillamine [SNAP], a nitric oxide precursor (L-arginine) or a degradation product of SNAP (N-acetylpenicillamine) on infarct size in these models.

RESULTS

Severity of myocardial injury was significantly exacerbated in cholesterol-fed rabbits (75.2 +/- 4.4% [mean +/- SEM]) compared with that in non-cholesterol-fed rabbits (53.2 +/- 5.2%). This exacerbation was prevented by treatment with SNAP (50.2 +/- 6.4%) but not with L-arginine (70.5 +/- 6.0%) or N-acetylpenicillamine (70.4 +/- 4.8%) in cholesterol-fed-rabbits. However, SNAP did not limit infarct size in non-cholesterol-fed rabbits (60.8 +/- 4.2%). The rate-pressure product was similar during the course of the experiment in all the groups.

CONCLUSIONS

Myocardial damage induced by ischemia-reperfusion was significantly exacerbated in rabbits fed a long-term cholesterol-rich diet but was effectively reversed by treatment with a nitric oxide donor. However, this agent did not limit infarct size in normal rabbits. Thus, a nitric oxide donor reduces myocardial infarct size in atherosclerotic but not in nonatherosclerotic rabbits.

Dissociation of early and late protective immunity to the nematode Nippostrongylus brasiliensis in Brown Norway and Fischer-344 rats

Worm expulsion of, and IgE and interferon (IFN)-gamma responses to, Nippostrongylus brasiliensis were studied in 2 rat strains, Brown Norway (BN) and Fischer (F)-344. BN rats expelled the majority of worms by day 14 post-infection (p.i.) with approximately 6% of worms surviving for at least 3 weeks. In F-344 rats, worm expulsion was delayed by 2 days relative to that in BN, while the numbers of residual worms were significantly fewer than in BN, suggesting that different immune mechanisms are involved in early and late phases of immunity. Total serum IgE, as well as in vitro IgE production by mesenteric lymph node (MLN) cells, was increased 2 weeks p.i., the levels being markedly higher in BN than in F-344 rats. Serum rat mast cell protease II was also increased more significantly in BN than in F-344 rats. In contrast, production of IgG2a and IFN-gamma by MLN and spleen cells was found to be higher in F-344 than in BN rats. These results indicate that the early worm expulsion is correlated with the host IgE and mast cell responsiveness, whereas the persistence of infection in the late period may be controlled by different immune mechanisms.

Insulin resistance and body fat distribution

Body fat distribution can be assessed by computed tomography (CT). The ratio of umbilicus was used to classify obese subjects as having visceral fat obesity (VFO) or subcutaneous fat obesity (SFO). Serum triglyceride and total cholesterol levels and plasma glucose area in an oral glucose tolerance test were higher in patients with VFO than in those with SFO. Significant positive correlations were demonstrated between V/S ratio and plasma glucose area, serum triglyceride level, and total cholesterol level as well as systolic or diastolic blood pressure. VFO was more frequently associated with coronary artery disease. Moreover, VFO was more often accompanied by multiple risk factors than was SFO. Steady-state plasma glucose (SSPG) level was significantly higher in patients with VFO than with SFO, suggesting that insulin resistance may be more remarkable in VFO than in SFO. Furthermore, visceral fat accumulation was also associated with these complications even in nonobese subjects. Visceral fat area (VFA) was significantly correlated with fasting plasma glucose, serum triglyceride, and total cholesterol levels. Animal models such as Goto-Kakizaki (GK) rats with ventromedial hypothalamus (VMH) lesions and Otsuka-Long-Evans-Tokushima-Fatty (OLETF) rats were accompanied by visceral fat accumulation and an early stage of aortic atherosclerosis. Aging, sex hormone, genetic, and dietary factors and physical inactivity may induce visceral fat accumulation. Visceral fat is characterized by its high lipogenic activity as well as its accelerated lipolytic activity. High levels of portal free fatty acids (FFAs) may eventually result in an enhancement of hepatic triglyceride synthesis, causing hyperlipidemia. High portal FFA levels would also induce insulin resistance, thereby causing glucose intolerance, hypertension, and finally atherosclerosis. We propose a term, "visceral fat syndrome," as a highly atherogenic state, which includes visceral fat accumulation, glucose intolerance (insulin resistance), hyperlipidemia, and hypertension.

[Development of multi-drug resistant mutants of clinical isolates of Pseudomonas aeruginosa after exposure to fluoroquinolone]

Eight multi-drug resistant mutants (4.94%) were found in 162 clinical isolates of P. aeruginosa after exposure to norfloxacin at different concentrations (1/4, 1/2, 1, 2 and 4 MICs) and were investigated for the mechanisms of drug resistance. All the mutants were eight-times more resistant to norfloxacin than the respective parents, and showed the cross-resistance to the other fluoroquinolones. However, these mutants differed in the drug-resistant patterns; the 94-74 mutant was resistant to carbenicillin, ceftazidime and chloramphenicol, TA-15 mutant was resistant to imipenem, and the 93-183 was resistant to carbenicillin, ceftazidime and gentamicin. TA-16 mutant only showed a marked decrease in the bacterial uptake of norfloxacin. Profiles of the outer membrane proteins of the mutants were analyzed by SDS-PAGE method. The six mutants, except for TA-52 and 93-183 mutants, increased the intensity of bands in the 46 KD region. Three mutants (TA-15, TA-16 and 93-183) decreased the intensity of 44 KD (OMPE) and also the former two decreased the intensity of 22 KD (OMP G). The gryA mutations associated with fluoroquinolone-resistance were investigated for the eight mutants, and the 93-183 mutant showed to have the gyrA mutation caused by the alteration in the amino acid sequence of gyrA; Thr-83 (ACC) to Ile (ATC). The result of the present study indicate that multi-drug resistance of clinical isolates of P. aeruginosa develops through different types of mechanisms, and is not easily explained fully by the present results, and suggest that many factors attributed to the development of the resistances in those mutants remains to be clarified.

[An immunohistological study on expression of glutathione S-transferase pi (form) in human endometrial carcinoma]

Ninety-five specimens from patients with endometrial carcinoma (82 of endometrial type, 6 of adenoacanthoma, 4 of adenosquamous carcinoma, 3 of atypical endometrial hyperplasia) and 13 with ovarian endometrioid carcinoma were stained immunohistochemically with a rabbit polyclonal antibody prepared against the placental form of the enzyme glutathione S-transferase pi (GST-pi). Histological studies showed that the degree of staining decreased as the tumor lost its differentiation in endometrial carcinoma, but the degree of staining was independent of the differentiation in the case of ovarian endometrioid carcinoma. A comparison between the grade of staining of GST-pi in 82 cases of the endometrial type of endometrial carcinoma and 13 cases of ovarian endometrioid carcinoma revealed a stronger stain for the endometrial carcinoma than for ovarian endometrioid carcinoma (p < 0.01, Mann-Whitney's U test). Therefore, the GST-pi value for endometrial carcinoma was different from that for endometrioid carcinoma. In general, as compared with ovarian endometrioid carcinoma, endometrial carcinoma is considered to be resistant to chemotherapeutic agents. In conclusion, these results suggest that there is an apparent correlation between the GST-pi value and chemoresistance of the tumor.

[Adjuvant chemotherapy with cyclophosphamide, adriamycin, and CDDP (CAP) for high risk endometrial cancer after complete surgery]

One hundred and six patients with endometrial cancer were treated at Tsukuba University Hospital between 1983 and 1992. Sixteen patients who underwent complete resection were at high risk for recurrence and were given adjuvant platinum-based, multiagent chemotherapy instead of adjuvant radiotherapy. Eligibility criteria included outer-third myometrial invasion (group 1; n = 5), pelvic lymph node metastasis (group 2; n = 3) or both myometrial invasion and lymph node metastasis (group 3; n = 8). Of these three groups at high risk for recurrence, each patient in groups 1 and 2 developed recurrence and died. In group 3 two patients developed recurrence and one patient has died. There was one treatment death due to neutropenic sepsis in group 3. The recurrence sites in all four patients were local and no distant recurrence was noted. In other words, of 15 patients (excluding one treatment death) at high risk for recurrence, three of 12 patients (25%) with deep myometrial invasion and three of 10 patients (30%) with positive pelvic lymph nodes developed recurrence and died. The other 12 patients (include one patient with recurrence; 100 months) have survived for a long interval (range, 45-131 months). The survival rates for stage I, II, III, and IV are 92.6, 89.5, 60.0%, respectively. Patients with stage I in this study had a better survival than those with stage I in the 1984 annual report of the Japan Society of Obstetrics and Gynecology (p < 0.05). The findings of this prospective clinical trial supported those of the randomized trial comparing adjuvant CAP with radiation therapy.

Establishment of a novel embryonic stem cell line by a modified procedure

To generate mutant mice, embryonic stem (ES) cells are used as a vehicle for introducing mutations. The establishment of ES cells is difficult because it requires specific skills and it is time-consuming. We established a novel ES cell line derived from hybrid mice between C57BL/6 and DBA/2 using a modified method. To collect a large number of preimplantational embryos, we collected embryos at the 8-cell stage and cultured them to blastocysts, whereas the usual procedure of preparing the delayed blastocysts demands technical skills. To eliminate unnecessary female cells at an initial stage of inner cell mass culture, male clones were selected by polymerase chain reaction to detect the mouse Sry gene. The established ES cell line efficiently contributed to the germ-line when injected into 8-cell embryos of ICR mice. This potency was maintained after manipulation throughout gene targeting.