CEA response at four weeks as an early predictor for outcomes in patients (pts) with metastatic colorectal cancer (mCRC) treated with first-line cetuximab-based chemotherapy: A STEP-analysis in the JACCRO CC-05/06 trials

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Background: We have reported that carcinoembryonic antigen (CEA) response correlated with clinical outcomes of 1st-line cet-based therapy (Target Oncol 2017). Early tumor shrinkage (ETS) is considered to be an on-treatment biomarker for outcomes of chemotherapy; however, clinical biomarkers to predict outcomes earlier are warranted. Methods: This study included 69 pts who were assessable for CEA at baseline and 4 wks, and with observed survival time from 2 phase II trials of 1st-line therapy for KRAS exon2 wild-type mCRC; JACCRO CC-05 of cet plus FOLFOX (UMIN000004197) and CC-06 of cet plus SOX (UMIN000007022). We investigated the influence of baseline age, gender, PS, primary tumor sidedness (PTS), number of tumor sites, as well as the CEA decrease at 4 wks to the patient’s OS and PFS. Results: PTS and the CEA decrease at 4 wks were found to be important predictors to OS and PFS. Baseline CEA and CEA decrease at 4 wks were median of 31.0 (range, 1.0-20920.0) and median of 35% (range, -259%-97%), respectively. The STEP-analysis indicated that CEA response was most significantly associated with OS when a cut-off value of 50% for CEA-responder (HR 0.49, log-rank test p = 0.03). Median OS in responders (n = 25) and non-responders (n = 44) were 36.2 m and 21.5 m, respectively. When the same cut-off value was used, median PFS in responders and non-responders were 11.6 m and 6.5 m, respectively (HR 0.64, log-rank test p = 0.08). In addition, a multivariate Cox Proportional-Hazards Model with both PTS and CEA response as risk factors showed that PTS correlated with both OS and PFS. In pts with left-sided tumors, non-responders (n = 33) had shorter OS and PFS compared to responders (n = 23). In the above 2-covariate Cox proportional hazard model, adjusted HR for CEA 50% decrease is 0.55, p = 0.1; adjusted HR for PTS is 2.66, p = 0.008. Conclusions: Our analysis suggests 50% CEA decrease at 4 wks as an early on-treatment biomarker for 1st-line cet-based therapy in mCRC. It may potentially predict outcomes earlier compared to ETS. Also, CEA response at 4 wks may differentiate pts who receive more benefit from cet treatment in left-sided tumors. Clinical trial information: UMIN000004197 and UMIN000007022.

[Multicentral Questionnaire Results for Consciousness of Medical Personnel on Chemotherapy for Gastric and Colorectal Cancer]

When a medical provider(medical personnel)becomes a medical receiver(patient), does the consciousness about chemotherapy change ? If yes, what is the main reason ? In this study, we conducted a questionnaire on the consciousness of doctors and pharmacologists engaged in chemotherapy for gastric and/or colorectal cancer. The number of questionnaires collected was 83 and 92 for gastric and colorectal cancer, respectively. In adjuvant chemotherapy, 5%and 4%do not want to receive any chemotherapy for gastric and colorectal cancer if they are patients. The main reasons are binding hours, side effects, and no wish for life extension. About 11%and 9%change their consciousness regarding chemotherapy according to whether they are care providers or receivers. The main reasons are medical perspective and their sense of duty. In chemotherapy for advanced cancer, 6% and 5% of gastric and colorectal cancer patients, do not want to receive any chemotherapy. The main reasons are low expectations for being cured, binding hours, and no wish for life extension. Further, 21%and 14%wish to have limited chemotherapy. As regards consciousness on chemotherapy, 26% and 18% reported changes according to whether they are providers or receivers. The main reasons are medical perspective and their sense of duty. As for the purpose of chemotherapy for advanced gastric and colorectal cancer, 96% and 43% answered prolonging life and relief, respectively. The proportion of persons who answered complete cure is statistically higher in colorectal(32%)than in gastric cancer(18%). The most common answer for an adverse event they want to avoid if they are patients is peripheral neuropathy. These results clearly demonstrate that a considerable proportion of medical personnel hold a negative attitude against or are reluctant to receiving chemotherapy, especially for advanced gastric and colorectal cancer. It is of great importance to make use of these results in clinical practice.

Early Tumor Shrinkage and Depth of Response as Predictors of Favorable Treatment Outcomes in Patients with Metastatic Colorectal Cancer Treated with FOLFOX Plus Cetuximab (JACCRO CC-05)

BACKGROUND

Retrospective studies have found that early tumor shrinkage (ETS) and depth of response (DpR) are associated with favorable outcomes in patients with metastatic colorectal cancer (mCRC); however, few prospective studies have evaluated ETS and DpR.

PATIENTS AND METHODS

We performed a phase II study of FOLFOX plus cetuximab as first-line treatment in Japanese patients with KRAS wild-type mCRC. The primary endpoint was response rate (RR), and secondary endpoints included progression-free survival (PFS), overall survival (OS), chronological tumor shrinkage (evaluated every 8 weeks), and safety. The association of ETS and DpR with survival time was analyzed using Spearman's rank correlation coefficient.

RESULTS

In 54 participants, the RR, median PFS, and OS were 66.7 % (95 % CI, 53.4-77.8 %), 11.1 months, and 33.9 months, respectively. There was no unexpected toxicity. Forty (80 %) of 50 assessable patients had ETS, which was associated with prolonged PFS and OS (11.3 vs. 3.7 months, HR 0.26, p = 0.0003; 42.8 vs. 9.0 months, HR 0.40, p = 0.0279, respectively). Median DpR was 56.3 %. The DpR correlated with OS (r _s = 0.314, p = 0.027) as well as post-progression survival (PPS) (r _s = 0.366, p = 0.017). Interestingly, DpR was moderately associated with OS and PPS (r _s = 0.587, r _s = 0.570, respectively) in patients harboring tumors with larger target lesions, but was not associated with OS or PPS in patients with smaller target lesions. FOLFOX plus cetuximab was active as a first-line treatment for Japanese mCRC patients, with no unexpected toxicities.

CONCLUSIONS

Our prospective evaluation of chronological tumor shrinkage showed that ETS and DpR correlate with outcomes in patients with KRAS wild-type mCRC who receive cetuximab-based chemotherapy (UMIN000004197).

Laparoscopic versus open adrenalectomy for adrenal myelolipoma

Introduction

Earlier reports of laparoscopic adrenalectomy (LA) for adrenal myelolipoma are limited.

Presentation of case

Between June 2000 and September 2012, we performed right adrenal resections using LA and open adrenalectomy (OA) in patients with myelolipoma (n = 3 and n = 3, respectively). Then, we evaluated patients' background characteristics and short- and long-term outcomes for both groups. The median maximum diameters of tumors were 3.5 (3.0–4.4) cm and 7.1 (7.0–9.5) cm for the LA and OA groups, respectively. The median durations of the operation were 152 (117–188) min and 218 (153–230) min, and the median blood loss volumes were 50 (20–160) mL and 290 (62–1237) mL in the LA and OA groups, respectively. The median postoperative lengths of hospital stay were 4 (4–4) days and 11 (11–13) days for the LA and OA groups, respectively. Conversion from LA to an open approach during surgery was not necessary in any of the cases. Additionally, perioperative morbidity and mortality were not observed.

Discussion

The limitation of this study is its methodological design; it is a case series and not a matched-control study, which would be difficult to conduct owing to the rare nature of adrenal myelolipoma. However, we esteem that LA will become widespread in the future because it is feasible, cosmetic, and less invasive.

Conclusion

LA was a safe, feasible, and effective approach to adrenal myelolipoma, assisted by advancement in preoperative imaging diagnostic techniques.

A phase II study of cetuximab (cet) and mFOLFOX6 in metastatic colorectal cancer (mCRC) (JACCRO CC-05)

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Background: FOLFOX4 combined with cet for mCRC patients (pts) with KRAS wild tumor demonstrated the prolonged progression-free survival (PFS) with higher response rate (RR) in the OPUS study. To evaluate the clinical efficacy and safety of the cet plus mFOLFOX6, we conducted a multi-center phase II study of Japanese pts. Methods: In this trial, pts with KRAS wild type tumor and receiving no prior chemotherapy for mCRC were treated with cet (initial dose 400, and 250 mg/m2 weekly) followed by mFOLFOX6 (oxaliplatin 85mg/m2, l-leucovorin 200 mg/m2, fluorouracil, as 400mg/m2 intravenous bolus then 2,400mg/m246-hour continuous infusion). The treatment was repeated every 2 weeks. The primary endpoint was RR evaluated by the external review board according to RECIST v1.1. Secondary endpoints included PFS, OS, % chronological change at the base line and safety. Results: A total of 57 pts were enrolled from August 2010 to September 2011. The median age was 60 years, 65% of pts were male, and ECOG PS 0 was observed in 91% of pts. All pts had EGFR-expressing disease. The median treatment courses were 21 (cet) and 10 (FOLFOX). The RR was 66.7% (95%CI, 53.4 to 77.7). Complete remission was observed in 5 cases (9.3%). The median PFS was 11.1 months (95%CI, 8.0 to 14.7). The early tumor shrinkage (ETS; over 20% regression at 8 weeks) was observed in 80% of pts, and the PFS for pts with ETS was statistically significantly prolonged as compared with pts without ETS (median PFS, 11.5 vs. 3.7 months, respectively; p = 0.0002). The OS was not reached at the time of median follow-up (19.2 months). Grade 3 or worse adverse events were neutropenia (48.2%), leucopenia (22.2%), rash acneform (20.4%), and peripheral neuropathy (18.5%). Conclusions: The first-line cet+mFOLFOX6 has an acceptable safety profile and demonstrates advantages in response rate for pts with KRAS wild tumor. The first-line cet+mFOLFOX6 should be considered as one of the recommended treatment regimens for pts with KRAS wild tumor. Update survival data will be presented. Clinical trial information: UMIN000004197.

[Coproductive teamwork in surgical cancer treatment]

With regard to surgical treatment of cancer, there is a strong demand for safe treatment with few errors: treatment must be based on transparency, understandability, and rationality. There is also demand for treatment which is quick, efficient and not wasteful. Rather than maintaining our current pyramidal system which has doctors standing as authorities at the top, there is a need for a flat, non-authoritarian system at every level and section of the hospital. As we change methodology, electronic medical records and clinical pathways will be important tools. Among the surgical department's treatment team in our hospital, there are many branches at work on peri-operative management aside from operations; There are teams for infection control (ICT), nutrition support (NST), decubitus and stoma management, rehabilitaion, and chemotherapy, and team cooperation after discharge from hospital. In addition, the collaborative and coproductive team focusing on pain releif and palliative care in terminal phase (PCT) is important. Having introduced each of the parts of team treatment within the setting of the surgical department, the need now for strong leadership from young and brightful surgeons is also emphasized.

Utility of preoperative small-bowel endoscopy for hemorrhagic lesions in the small intestine

PURPOSE

We evaluated a small group of patients with hemorrhagic lesions in the small intestine diagnosed preoperatively by video capsule endoscopy (VCE) and/or double-balloon endoscopy (DBE), who underwent surgery in our hospital.

METHODS

The subjects were 20 patients with hemorrhagic lesions in the small intestine diagnosed preoperatively by VCE and/or DBE, who underwent surgery between April 2004 and December 2008.

RESULTS

VCE, DBE, and computed tomography were performed in 12, 17, and 20 patients, respectively. Eleven patients also had a biopsy taken during DBE, resulting in a definitive diagnosis in eight. Because of the risk of hemorrhage during DBE in five patients, a biopsy was not taken and the sites of the lesion were marked in these patients. Twenty patients underwent surgery, and the diagnoses were small-intestinal cancer in eight, gastrointestinal stromal tumor in seven, arteriovenous malformation in two, and Crohn's disease, angioectasia, and leiomyoma in one each. The interval between the onset of symptoms and surgery was less than 50 days for six patients, 50-100 days for two, 100-200 days for five, and more than 200 days for seven.

CONCLUSION

Preoperative small-bowel endoscopy proved useful for diagnosing the cause of hemorrhagic lesions in the small intestine.

Interstitial lung disease during chemotherapy combined with oxaliplatin and/or bevacizumab in advanced colorectal cancer patients

OBJECTIVE

Interstitial lung disease in patients with colorectal cancer during chemotherapy combined with bevacizumab is rare.

METHODS

We reviewed 104 colorectal cancer patients treated with standard chemotherapy with bevacizumab and examined the incidence of interstitial lung disease and its clinical features.

RESULTS

We identified interstitial lung disease in four patients (3.85%). All patients were male. The median age was 64.5 years. Three of four patients had a history of smoking; median smoking index was 40 pack-years. Except one patient who had asymptomatic pulmonary fibrosis, chest computed tomography before chemotherapy showed no fibrotic changes. Pulmonary function test before chemotherapy showed normal values. All patients had received median 10 cycles (range 10-15 cycles) of FOLFOX before the onset of interstitial lung disease. Interstitial lung disease developed during FOLFOX + bevacizumab in two patients and during FOLFIRI + bevacizumab in two patients. The initial symptom of interstitial lung disease was fever in all patients. The median duration from the last chemotherapy to the onset of interstitial lung disease was 3.5 days (range 2-8 days). Three of four patients showed Grade 3 or more severity of interstitial lung disease according to Common Terminology Criteria for Adverse Events v3.0. High-dose steroid therapy was effective in all patients.

CONCLUSIONS

Interstitial lung disease induced by standard chemotherapy with bevacizumab is rare, but rapidly progressed and were severe in our experience.

Fat replacement of the distal pancreas in a case of advanced gastric cancer

Preoperative computed tomography in a 67-year-old man admitted with type 2 advanced gastric cancer involving the upper body of the stomach revealed marked atrophy of the left lobe of the liver and atrophy of the distal pancreas. Total gastrectomy with D2 lymph node dissection was planned; however, additional distal pancreatectomy with splenectomy was also performed during the operation because of direct invasion of the pancreas by the gastric cancer. Histopathologic examination of the resected pancreas revealed the absence of lobules, acini, conduits, and pancreatic ducts, with only islets of Langerhans found scattered in the adipose tissue. The findings revealed that the gastric cancer had directly invaded the fat, replacing the distal pancreas. In patients with fat-replaced pancreas, preoperative evaluation of direct invasion of adjacent organs/tissues by gastric cancer is difficult.

Effects of Applying Povidone-Iodine Just before Skin Closure

Many surgeons apply povidone-iodine (PVP-I) to the skin around an incision before closing a wound to reduce wound infection rates. However, the effectiveness of this procedure has not been proven. Forty-seven cases of gastric surgery and 60 cases of colorectal surgery performed at Kanto Medical Center between July 2004 and December 2004 were randomly assigned to the group with PVP-I or the group without PVP-I. Wound infection and surgical site infection (SSI) rates were compared between these two groups. Applying PVP-I was effective in eliminating skin contamination, as cultures became negative in all cases after applying PVP-I. However, this study could not demonstrate the reduction of wound infection or SSI in the group with PVP-I, possibly because the number of cases in this study was too small to make a difference. Subcutaneous tissue contamination was considered a more important factor than skin contamination in causing wound infection.

Secondary myelodysplastic syndrome after small cell lung cancer and esophageal cancer

A 50-year-old man was referred to our department with esophageal cancer. He had past history of small cell lung cancer treated with chemoradiation therapy 10 years prior. The disease was evaluated as complete remission after chemoradiation therapy and no recurrence had been observed. Esophagectomy accompanying postoperative chemotherapy was applied, but he died of secondary myelodysplastic syndrome with its acute myeloblastic transformation. Risk evaluation revealed a high incidence of esophageal cancer after radiation therapy and hematological malignancies after chemoradiation therapy in usual regimen with topoisomerase inhibitor or alkylating agents. Chemoradiation therapy is thought to be one of a few highly effective therapeutic alternatives and many complete remission cases have been reported in small cell lung cancer or esophageal cancer. In post-therapeutic follow up of patients with such past therapeutic histories, we should be cautious about secondary malignancies even if primary malignant disease was evaluated as complete remission in long past history.

Development of clinical pathway in S-1 chemotherapy for gastric cancer

We have developed a clinical pathway to enable the safe continuous administration of S-1 (TS-1) in ambulatory care for patients with advanced gastric cancer. The S-1 clinical pathway includes a pathway for clinicians, a pathway for patients, and such assist tools as a medication diary, an explanatory document containing instructions relating to patient compliance, a table of associations between adverse reactions and prodromes, and general principles for dose reduction and withdrawal. These pathways and assist tools will improve the patient's perception of adverse reactions, thereby contributing to early discovery and rapid action against adverse events. The S-1 clinical pathway has been used with ten patients. S-1 administration has been continued in seven patients. In four of the seven patients, continued administration on the occurrence of adverse reactions was made possible by the use of appropriate measures such as drug withdrawal or dose reduction. It was confirmed that the S-1 clinical pathway was a useful tool for cancer chemotherapy in ambulatory care.

A case of bilateral obturator hernias; feasibility of combination study of computed tomography and ultrasonography to make diagnostic and therapeutic strategies

Bilateral obturator hernias were diagnosed by computed tomography in a 77-year-old female. Ultrasonography was also performed and ultrasonographical difference was observed between right and left. This contributed the preoperative diagnosis of unilateral incarceration. Combination study with computed tomography and ultrasonography is thought to be feasible to make diagnostic and therapeutic strategies of obturator hernia.

Establishment of an optimized set of 406 microsatellite markers covering the whole genome for the Japanese population

Microsatellites, an essential tool for genetic linkage analyses, are selected in genetic studies on the basis of both informativeness and their positions with respect to one another on the genetic map. In order to establish a microsatellite marker set useful for linkage studies in the Japanese population, we first genotyped 64 unrelated Japanese subjects, using 400 microsatellite markers from a commercially available set (ABI PRISM Linkage Mapping Set-MD10) and then determined the allelic frequencies and heterozygosities for these marker loci in the population. In order to optimize the set, we replaced 41 markers having a heterozygosity lower than 0.6 with as many informative markers in the corresponding loci, and newly added six markers in the set to minimize the several gaps found at intervals of over 20 cM. We finally established a set comprising 406 microsatellites with average intervals of 9cM (maximum, 17 cM) and minimum heterozygosities of over 0.6 (mean, 0.76). All data generated in this study, including the specific polymerase chain reaction (PCR) primer sequences of the newly added markers, are freely available to all researchers at our web site. The genetic tool established here should facilitate genetic linkage studies of various hereditary diseases, especially in the Japanese.

Gender-specific haplotype association of collagen alpha2 (XI) gene in ossification of the posterior longitudinal ligament of the spine

Among Japanese, ossification of the posterior longitudinal ligament of the spine (OPLL) is a leading cause of myelopathy, showing ectopic bone formation in the paravertebral ligament. We have provided genetic evidence that the collagen alpha2 (XI) (COL11A2) locus of chromosome 6 constitutes susceptibility for OPLL. Five distinct single nucleotide polymorphisms (SNPs), identified in COL11A2, were combined to construct possible haplotypes by the use of a maximum likelihood program. Estimated haplotype frequency was compared in OPLL patients and non-OPLL controls. We report a gender-specific association of the COL11AA2 haplotvpe with OPLL. The frequency of the most commonly observed haplotype was significantly higher in male patients (P = 0.0003) compared with controls, but not in female patients (P = 0.21). OPLL is predominantly observed in males. with a prevalence ratio of 2:1, and our gender-specific associations indicate that genetic factors involving COL11A2 play a specific role in the etiology of OPLL exclusively in males.

A new murine zinc finger gene, Opr

Here we report a novel murine zinc-finger gene, Opr, belonging to the opa/Zic family. Opr is expressed in the entire embryonic ectoderm before gastrulation, but gradually restricted to the anterior part from the mid to late streak stage. At the beginning of neural induction, Opr is expressed throughout the anterior neural plate, but is soon restricted to the neural ridge. After neural tube closure, its expression is maintained in the dorsal part of the neural tube, except for the roof of the telencephalon. Opr is also expressed in somites and limbs.

[Improving the anti-tumor activity of 5-fluorouracil by methotrexate]

The first clinical application of biochemical modulation (BCM) of 5-fluorouracil (5-FU) was the sequential MTX/5-FU regimen proposed in 1977 by Bertino for the treatment of colorectal cancer. In Japan, sequential MTX/5-FU therapy was mainly used as a new method of treating gastric cancer, and attracted a great deal of attention because it proved effective in many cases of advanced gastric cancer that had been unresponsive to the previous chemotherapy, particularly scirrhous gastric cancer with poor prognosis. Its therapeutic efficacy varied according to histologic type, it was effective in cases of peritoneal dissemination and disseminated intravascular coagulopathy (DIC), it was associated with fewer adverse effects, and it was a multidrug chemotherapy based on a clear rationale. With sequential MTX/5-FU therapy as a starting point, fundamental studies of BCM and its clinical applications have expanded rapidly in Japan. This paper provides an outline of sequential MTX/5-FU therapy from the aspects of its mechanism of action, indications, therapeutic efficacy, relevance to adjuvant therapy, counter-measures to adverse effects, and emergence of resistance to the drugs involved. The high therapeutic efficacy of this therapy in certain histologic types is also discussed, and its combined use with other forms of BCM, as in triple BCM (LV/5-FU + CDDP/5-FU + MTX/5-FU), is introduced.

Effects of lanthanide ions on the binding ability of annexin V to phospholipid vesicle

The effects of lanthanide ions (Ln(3+)), La(3+), Ce(3+), Gd(3+), and Tb(3+), on the binding ability of annexin V to phospholipid vesicle were studied, and compared with that of Ca(2+). The energy transfer following excitation at 278 nm was accompanied by a small decrease (about 3%) in the fluorescence signal (310-315 nm) of the aromatic amino acid residues, followed by strong re-emission of annexin V-bound Tb(3+) at 547 nm. The results of the titration of Tb(3+)-protein interactions using the rate dialysis method suggest that there are two high affinity metal binding sites on annexin V, to which Tb(3+) binds with an average dissociation constant, Kd, of about 2.11 x 10(-7) M. The Ln(3+) seemed to assist the anticoagulant action of annexin V because it binds more strongly to phospholipid than Ca(2+) does. Annexin V had the same ability to bind phospholipids in 10 mu M Ln(3+) as it did in 1 InM Ca(2+), showing that it binds to anionic phospholipids with Ln(3+) more strongly than it does with Ca(2+).

Anticoagulant action of rare earth metals

Some of the lanthanides, the rare earth metals, lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm), terbium (Tb), dysprosium (Dy), erbium (Er) and ytterbium (Yb) prolonged the clotting time of normal human plasma in a dose-dependent manner when clotting was induced either by thromboplastin or by kaolin in the presence of cephalin and Ca2+. They also prolonged the activated factor X induced clotting time of platelet-rich plasma. The amidolytic activities of activated factor X and thrombin progressively decreased with increasing amount of rare earth metals. These results suggested that the rare earth metals appear to show their anticoagulant effect with mechanisms in part the inhibition of the enzymatic activities of both activated factor X and thrombin.

[Surgical treatment of metastatic lung cancer from colorectal cancers]

Based on conclusions obtained after the observation of 61 colorectal cancer patients with a lung metastasis, the resection of lung metastasis as a therapy was evaluated. Among these 61 patients, only 5 patients had been identified as having a lung metastasis at the time of resection of the primary lesion, whereas the other 56 patients developed the lung metastasis after the curative resection of the colorectal cancer. Only one patient with a synchronous lung metastasis and twelve patients (eleven with a solitary metastatic lesion and one with multiple metastatic lesions) with metachronous lung metastasis underwent removal of the lung metastasis. The three-year survival rate was 65.2% in the metachronous group.

Studies on (n, alpha) recoils of 6Li and 10B in the reactor UTR-Kinki by gas phase electrodeposition

The energies of recoil particles from (n, alpha) or (n, 2 alpha) reactions of Li and B were investigated by solid state detector and gas phase electrodeposition as previously reported on 228Th series. Nuclear reactor of UTR-Kinki was used as thermal neutron source. Particles from 6Li (n, alpha) 3T and 10B (n, alpha) 7Li were collected on a sheet of triacetate film by gas phase electrodeposition at atmospheric pressure. The film was etched with 6M-NaOH at 50 degrees C. The tracks thus obtained were taken as photographs with a microscope (X600). By counting the number of tracks on the film at various etching times, the energies of alpha-particles were evaluated according to the calibration curve of 227Ac series. Among various peaks of tract density, the two peaks having the evaluated values of 1.85 MeV for 6Li and 1.48 MeV for 10B agreed approximately with the theoretical values of 2.05 MeV and 1.47 MeV of alpha-particle energies for respective reactions.

[Focusing chromatography using a dilute precipitation reagent--separation of 226Ra decayed nuclides by potassium fluoride (author's transl)]

The electrophoresis of 226Ra and it's decayed nuclides was carried out by using hydrochloric acid in the positive electrode cell and aqueous solution of potassium fluoride in the negative electrode cell. Experimental factors, i.e. concentrations of potassium fluoride and hydrochloric acid, intensity of electric field, duration for electrophoresis and pH value of the potassium fluoride solution etc. were examined. The sample solution was of 0.01 M hydrochloric acid with a tracer amount of 226Ra and 210Pb. Each of these nuclides was carrier free and was 4GB1/l(1 muCi/ml) in concentration. For the sake of autoradiography, a photoengraving film (Fujilith Ortho Film, TAC = 135) was made use of examining the locations of the separated radioactive bands obtained on the paper strip. Their beta and gamma radioactivities were detected as the film darkening on developing the film. According to the positions thus detected, the strip filter paper was cut into pieces and the species of radionuclides were determined by the measurements of energies and half-lives on beta and gamma rays. The locations of the separated alpha-radionuclides were decided by etching the surface of it's film with 6 M aqueous solution of sodium hydroxide and the species of radionuclides were determined by the solid state alpha-track detection method. As the result, the optimum conditions for the separation are to use 0.01 M hydrochloric acid in the positive cell and 0.005 M potassium fluoride of pH 6.2 in the negative cell, intensity of the applied electric field being 1000 V/30 cm, and electrophoresis time being 20 minutes. The proposed method gave good results for focusing and separating the radium series nuclides. Bands of 210Bi and 210Po were found on the positive electrode side, while the bands of 226Ra and 210Pb (containing 214Pb) were on the negative electrode side.

[Study on focusing chromatographic simultaneous determinations of 226Ra and its daughter nuclides by means of solid state alpha-tracks detection and beta-autoradiography (author's transl)]

In order to detect to radioactive band on the paper strip developed by focusing chromatography, plate-making-film was used for the autoradiography and beta-spots were photographed. Thereafter the film was etched with sodium hydroxide solution to find the alpha-tracks. Paper strip used for the sample was prepared by the precipitation focusing chromatography of 226Ra and its daughter nuclides using HCl-KF solution as a developer. The film used was not high in its beta-sensitivity, but because of its high resolution good photographic results were obtained according to the intensity of beta-activity when the proper conditions of photographic development were fulfilled. The simple alpha-spectrometry was made possible by counting the numbers of tracks according to the etching depth of the film. The film was hard and thick enough for etching with 6M sodium hydroxide solution at 50 degrees C for more than 50 hrs to measure the depth of tracks.