A Bayesian hierarchical survival model for the institutional effects in a multi-centre cancer clinical trial

In randomized clinical trials comparing treatment effects on diseases such as cancer, a multi-centre trial is usually conducted to accrue the required number of patients in a reasonable period of time. While we interpret the average treatment effect, it is necessary to examine the homogeneity of the observed treatment effects across institutions, that is, treatment-by-institution interaction. If the homogeneity is confirmed, the conclusions concerning treatment effects can be generalized to a broader patient population. In this paper, a Bayesian hierarchical survival model is used to investigate the institutional effects on the efficacy of treatment as well as on the baseline risk. The marginal posterior distributions are estimated by a Markov chain Monte Carlo method, that is, Gibbs sampling, to overcome current computational limitations. The robustness of the inferences to the distributional assumption for the random effects is also examined. We illustrate the methods with analyses of data from a multi-centre cancer clinical trial, which investigated the efficacy of immunochemotherapy as an adjuvant treatment after curative resection of gastric cancer. In this trial there is little difference in the treatment effects across institutions and the treatment is shown to be effective, while there appears to be substantial variation in the baseline risk across institutions. This result indicates that the observed treatment effects might be generalized to a broader patient population.

Antibody fragments as inhibitors of Japanese radish acid phosphatase

VH (heavy-chain variable region) and VL (light-chain variable region) genes were amplified by PCR from hybridomas producing MAb-11 and MAb-18 which inhibited Japanese radish acid phosphatase. Nucleotide sequencing of the V genes demonstrates that the MAbs contained similar VH and identical VL domains. Initially, the VH and VL genes were expressed in Escherichia coli as single-chain Fv (ScFv) fragments. Fragments ScFv-11 and ScFv-18, named for MAb-11 and MAb-18, respectively, inhibited the enzyme activity to the same extent as the intact MAbs. Both of the antibody fragments widely cross-reacted with other phosphatases, including some phosphomonoesterases and phosphodiesterases from different sources. ScFv-18 also inhibited acid phosphatase from a different origin, but stimulated the activity of alkaline phosphatase from calf intestine. The PCR-amplified VH and VL genes were subsequently expressed separately in Escherichia coli as fusion products with glutathione S-transferase. The fusion proteins had little effect on Japanese radish acid phosphatase. Furthermore, a large number of recombinant ScFv fragments specific to the acid phosphatase were generated by using a bacteriophage expression system and a mouse ScFv gene library. These ScFv fragments had a range of effects on the enzyme activity, including inhibition, stimulation, and none. Among them, an ScFv fragment, designated ScFv-G7, inhibited more strongly than ScFv-11 and ScFv-18.

The cbaAB genes for bo3-type cytochrome c oxidase in Bacillus stearothermophilus

Structural genes were cloned for cytochrome bo3-type cytochrome c oxidase recently isolated from a Gram-positive thermophile Bacillus stearothermophilus. Sequencing and Northern blotting analyses indicated that the two genes cbaA and cbaB composed an operon encoding for subunits I and II, respectively, and that the oxidase was SoxB-type. They are the first genes for a SoxB-type cytochrome c oxidase whose natural substrate is known.

Effect of protein kinase C inhibitors on cardioprotection by ischemic preconditioning depends on the number of preconditioning episodes

OBJECTIVES

This study examined the possibility that the role of PKC in [corrected] PC, and thus the response to PFC inhibitors, may differ depending on how many ischemic episodes are employed to precondition the heart.

METHODS

In the first series of experiments, myocardial infarct was induced by 30 min of coronary occlusion and 3 h of reperfusion in the rabbit. Infarct size was determined by tetrazolium staining and expressed as a percentage of area at risk (%IS/AR). Prior to the 30-min ischemia, rabbits were subjected to no PC, single PC (i.e., PC with an episode of 5 min ischemia/5 min reperfusion), and repetitive PC (2 cycles of 5 min ischemia/5 min reperfusion) with or without one of three treatments: polymyxin B (PolyB), staurosporine (Stauro), and 8-sulfophenylthephylline (SPT). In the second series of experiments, the rabbits received 5 min of coronary occlusion after repetitive PC with or without PolyB or Stauro treatment. Then, myocardial tissue in the ischemic region was sampled for assay of PKC activity. Untreated rabbits served as controls.

RESULTS

Single and repetitive PC limited %IS/AR to the same extent (%IS/AR = 9.8 +/- 1.9 and 10.4 +/- 2.3, both p < 0.05, vs. the control value of 44.5 +/- 3.4), and single PC was blocked by PolyB (%IS/AR = 43.9 +/- 2.7) and Stauro (%IS/AR = 31.5 +/- 3.2). Although the protocol of PolyB injection maintained the plasma PolyB level during sustained ischemia well above its Ki for PKC, this agent and also Stauro failed to abolish the protection by repetitive PC (%IS/AR = 21.6 +/- 3.0 and 11.4 +/- 4.3, respectively). SPT, an adenosine receptor antagonist, not only blocked single PC (%IS/AR = 44.4 +/- 4.4) but also attenuated protection by repetitive PC (%IS/AR = 28.3 +/- 3.6). Infarct sizes in non-preconditioned hearts were not modified by PolyB, Stauro, or SPT. The ratio of membrane fraction PKC activity to cytosolic fraction PKC activity was elevated by repetitive PC plus 5 min ischemia, and this change in PKC was inhibited in hearts given PolyB and Stauro.

CONCLUSIONS

In contrast to single PC, repetitive PC protects the heart against infarction even when PolyB and Stauro are administered to inhibit PKC during ischemic insult. This difference may be attributable to a PKC-independent mechanism, in which the adenosine receptor may be partly involved.

[Surgery and multidisciplinary treatment for colorectal cancer]

Evaluation of surgery and multidisciplinary treatment for colorectal cancer was performed based on the review of the results of clinical trials. Although most improvement in prognosis for colorectal cancer patients was obtained by the development of surgical techniques until the mid-70's, further extended surgery could not have demonstrated the obvious improvement in survival after the 80's. In this regard, various multidisciplinary treatments were evaluated by a meta-analysis of clinical trials. Among those modalities, preoperative irradiation for rectal cancer, postoperative adjuvant chemotherapy for resected colorectal cancer and biochemical modulation of 5-fluorouracil by methotrexate or leucovorin for advanced colorectal cancers proved to be significantly effective for improvement of prognosis. Clinical trials of immunochemotherapy using either levamisole or PSK for resected colorectal cancers, a trial of hepatic artery infusion for liver metastasis, and a trial of an adjuvant monoclonal antibody treatment, were also reported to demonstrate significant effects. For further progress in multidisciplinary treatment for colorectal cancers, standardization of the appropriate surgical technique for each stage of the disease is much anticipated.

Cold snare excision is a safe method for diminutive colorectal polyps

Cold snare excision (CSE) has proved to be an effective method for the destruction of diminutive polyps of the colon and rectum. We investigated the correlation between polyp size and bleeding time at the resected end after CSE, and also an appropriate measuring method using CSE. Eighty patients with single polyps were examined. Each polyp was identified as being 5 mm in diameter or smaller using the open-biopsy forceps technique (OBFT). The size of the polyp was calculated using our measuring system (SMS). Of the polyps identified as being 5 mm in diameter or less using OBFT, 15% were 6 mm or more using the SMS. CSE was performed for each polyp, and the time taken for the hemostasis (bleeding time of the CSE; BTCSE) was determined. In seventy-seven polyps that were 6 mm or smaller in SMS, a correlation was noted between SMS and BTCSE. In three polyps that were 7 mm or more by SMS, hemostasis took 10 min or more after CSE, and required electrocoagulation. These results suggest that CSE is a safe method for the removal of polyps determined to be 6 mm in diameter or smaller using the SMS.

A re-analysis of a randomized clinical trial for gastric cancer using interval censoring

In a previous randomized clinical trial against curatively resected gastric cancer, we compared the effect of immunochemotherapy to chemotherapy and obtained significantly better survival and disease-free survival time (DFS) in a combined therapy group. Although DFS was analysed with a conventional approach in which the onset of relapse was defined as the diagnosis of relapse, we considered it necessary to re-analyse the data and compare the results of an interval-censored approach with the conventional approach, in order to examine whether the conclusion might be altered depending on the approach.

Characterization of two terminal oxidases in Bacillus brevis and efficiency of energy conservation of the respiratory chain

The respiratory chain of Bacillus brevis was analyzed. Resting cells showed an H+/O ratio of 4.8-5.2 (5.01+/-0.26), when measured using an oxygen pulse method with endogenous substrates. This value is intermediate between those of Bacillus subtilis (about 4), which predominantly expresses cytochrome aa3-type quinol oxidase, and Bacillus stearothermophilus (about 6), which has quinol cytochrome c reductase plus caa3-type cytochrome c oxidase. Measurement of respiration with various substrates, and its inhibition by cyanide suggested that aa3-type quinol oxidase and caa3-type cytochrome c oxidase operate simultaneously in the respiratory chain of B. brevis. Both terminal oxidases were isolated by solubilizing B. brevis membranes with Triton X-100, and fractionating the extract using DEAE-Fractgel and gel-filtration columns. The quinol oxidase (aa3) was composed of four subunits (57, 34, 23, and 15 kDa), like its counterpart of B. subtilis, while three subunits (52, 34, and 22 kDa) were identified in the cytochrome c oxidase (caa3) preparation in B. stearothermophilus.

A novel cytochrome b(o/a)3-type oxidase from Bacillus stearothermophilus catalyzes cytochrome c-551 oxidation

Gram-positive thermophilic Bacillus species contain cytochrome caa3-type cytochrome c oxidase as their main terminal oxidase in the respiratory chain. To identify alternative oxidases, we isolated several mutants from B. stearothermophilus defective in the caa3-type oxidase activity [Sakamoto, J. et al (1996) FEMS Microbiol. Lett. 143, 151-158]. A novel oxidase was isolated from membrane preparations of one of the mutants, K17. The oxidase was composed of two subunits with molecular masses of 56 and 19 kDa, and contained protoheme IX, heme O, heme A, and Cu in a ratio of 1:0.7:0.2:3. CO difference spectra indicate that the high-spin heme is mainly heme O. These results suggest that the enzyme belongs to the heme-copper oxidase family and is a cytochrome b(o/a)3-type oxidase, whose high-spin heme is mainly heme O and partly heme A. The enzyme oxidized cytochrome c-551, which is a membrane-bound lipoprotein of thermophilic Bacillus. The turnover rate of the activity (Vmax = 190 s[-1]) and its affinity for cytochrome c-551 (Km = 0.15 microM) were much higher than those for yeast and equine heart cytochromes c. The oxidase activity was enhanced by the presence of salts and inhibited by sodium cyanide with a Ki value of 19 microM. The enzyme kinetics suggests that cytochrome c-551 is the natural substrate to this oxidase. Furthermore, the oxidase had similarity to cytochrome ba3-type oxidase from Thermus thermophilus in the subunit composition, partial amino acid sequence, and prosthetic groups, and therefore is suggested to belong to a unique subgroup of the heme-copper oxidase family together with the Thermus enzyme and archaeal oxidases such as Sulfolobus SoxABCD.

Imaging of recurrent intestinal carcinoma with indium-111-labeled anti-carcinoembryonic antigen monoclonal antibody CEA102

CEA102 is a mouse immunoglobulin G1 monoclonal antibody (mAb) that detects an epitope of carcinoembryonic antigen (CEA). The biodistribution and imaging characteristics of indium-111-labeled (111-In)-mAb CEA102 were studied in 1 primary and 9 extrahepatic recurrent intestinal carcinoma patients. Evaluation included antibody pharmacokinetics and assessment of antibody distribution in surgical specimens, in comparison with whole body imaging using a gamma camera, and imaging with single photon emission computed tomography. Selective mAb CEA102 localization to tumor tissue was demonstrated in 7 patients with tumors over 2 cm in size, and the external images correlated well with the results of surgical inspection, pathological examination, and tissue radioactivity measurements. Tumor:serum ratios ranged from 0.20:1 to 3.22:1, and serial biodistribution study of "regions of interest" also demonstrated a high radioactivity in the tumor. These results indicated the potential exploitability of the 111-In-labeled mAb CEA102 in radioimmunodetection of primary and extrahepatic recurrence of CEA-positive intestinal carcinomas.

Antigenic analysis of human herpesvirus 7 (HHV-7) and HHV-6 using immune sera and monoclonal antibodies against HHV-7

Using polyclonal and monoclonal (MAbs) antibodies to human herpesvirus 7 (HHV-7), we have studied HHV-7-specific polypeptides. Human sera were obtained during the convalescent phase from patients with exanthem subitum due to HHV-7, and at least 16 HHV-7-specific polypeptides with apparent molecular masses of 26-210 kDa were immuno-precipitated. Sera prepared in mice also precipitated at least 17 HHV-7-specific polypeptides with molecular masses of 26-210 kDa. Among them, the most commonly observed antigenic protein had an apparent molecular mass of 52 kDa. Forty-two clones secreting MAbs against HHV-7-specific proteins, as determined by immunofluorescence assays, were established from BALB/c mice immunized with HHV-7-infected cell extracts. Seven MAbs which immunoprecipitated HHV-7-specific polypeptides were further characterized. Two of these, MAbs 5E12 and 5F12, reacted predominantly with glyco-proteins of 78 kDa and 85 kDa, respectively, and possessed neutralizing activity. This suggests that there are at least two neutralization-inducing proteins in HHV-7. MAb 16B4 reacted with the major immunogenic protein of 52 kDa. Five of the 42 MAbs also reacted in immunofluorescence assays with HHV-6 antigens to the same degree as to HHV-7. Two other MAbs, 7C10 and 10F1, recognized an HHV-7 protein of 40 kDa, and only 7C10 cross-reacted with an HHV-6 protein of 45 kDa.

Identification and characterization of a novel human cortistatin-like peptide

Expressed sequence tags (ESTs) that showed significant homology to rat cortistatin (CST) were found in a human fetal brain cDNA library. A protein coded by the cDNA showed 55% identity to rat preprocortistatin in amino acid. Similarly in the generation of mature peptides from rat preprocortistatin, it was expected that cleavage at dibasic amino acids in the C-terminal portion of the coded protein might produce at least two different sizes of mature peptides with 29 and 17 amino acid residues, respectively. We chemically synthesized the predicted mature peptide with 17 amino acid residues (hCS-17) and examined its biological activities. It bound to all human somatostatin receptor (SSTR) subtypes in almost the same manner as rat CST-14. It also inhibited cAMP production induced by forskolin through SSTRs. Administration of hCS-17 to the cerebral ventricle showed flattening of cortical and hippocampal electroencephalograms in rats. These results indicate that a bioactive peptide encoded by the cDNA is a human counterpart corresponding to rat CST.

5-aminocoumarans: dual inhibitors of lipid peroxidation and dopamine release with protective effects against central nervous system trauma and ischemia

A series of 2,3-dihydro-5-benzofuranamines (5-aminocoumarans) were developed for the treatment of traumatic and ischemic central nervous system (CNS) injury. Compounds within this class were extremely effective inhibitors of lipid peroxidation in vitro and antagonized excitatory behavior coupled with peroxidative injury induced by spinal intrathecal injection of FeCl2 (mouse-FeCl2-it assay) in vivo. Selected compounds were tested for antagonistic activity on methamphetamine (MAP)-induced hypermotility resulting from dopamine release in the mouse brain. Among the compounds synthesized, compound 26n (2,3-dihydro-2,4,6,7-tetramethyl-2-[(4-phenyl-1-piperidinyl) methyl]-5-benzofuranamine) exhibited potent effects in these assays (inhibition of lipid peroxidation, IC50 = 0.07 microM; mouse-FeCl2-it assay, ID50 = 10.4 mg/ kg, po; MAP-induced hypermotility, 98% inhibition, 10 mg/kg, ip). The S-(+)-form of compound 26n dihydrochloride (TAK-218), which has 30 times more potent antagonistic activity on MAP-induced hypermotility than the R-(-)-form, improved more significantly the survival rate in the cerebral ischemia model (rat, 1-3 mg/kg, ip) during the period of 1-14 days after ischemia and decreased functional disorders in the traumatic brain injury model (rat, 0.1-1 mg/kg, ip) 3-14 days after injury. These results imply a role for dopamine in deterioration of CNS function after ischemic and traumatic injury. TAK-218 is a promising compound for the treatment of stroke and CNS trauma and is now under clinical investigation.

Analysis of specific accumulation of radiolabeled anti-carcinoembryonic antigen monoclonal antibody CEA 102 in colorectal cancer using computed radiography

The specific accumulation of radiolabeled anti-carcinoembryonic antigen (CEA) monoclonal antibody (MoAb) CEA 102 in colorectal cancers was investigated by autoradiography of surgical specimens using Fuji Computed Radiography (FCR). Five patients with colorectal cancer were injected intravenously with [13I]-labeled intact CEA 102 or its F(ab')2. Primary tumor and liver metastases were successfully detected by external scanning with gamma camera in four cases. Autoradiographic study using FCR showed predominant localization of [13I]-labeled CEA 102 in primary tumors and liver metastases in all cases. Even the small-sized liver metastasis (0.5 cm) was clearly visualized. The pixel distribution curves showed the heterogeneity of the distribution of administered MoAb in the tumors. In the quantitative distribution analysis of CEA 102, the uptake of the primary tumor was 10-fold greater than that of the normal colon mucosa. These results suggest that MoAb has great potential in radioimmunodetection as well as possible use in antibody-directed therapy.

[Administration of oral etoposide for one year as adjuvant chemotherapy for non-small cell lung cancer-side effect]

The possibility of using etoposide 25 mg daily as adjuvant chemotherapy for non-small cell lung cancer was discussed. Initially, 73 patients who had undergone resection participated in this trial; 49 of them were eligible, 24 including a patient over 70 years of age (8) took the drug for 1 year, 22 patients resigned from the study due to side effects, and a further 3 patients died during the trial. The main side effects observed were gastro-intestinal trouble (13) and pneumonia (4). The side effects of this drug appeared early in the treatment phase. During the first month of treatment, 9 patients discontinued the drug due to side effects, and 10 more did so within 4 months. To achieve optimal conditions for the trial study of low-dose etoposide it was found important to select patients under 70 years of age and to control side effects of the drug on the gastro-intestinal tract from the beginning.

Primary linitis plastica of the rectum: report of four cases and review of the literature

Primary linitis plastica of the rectum is a rare form of large bowel carcinoma, with only 30 cases having been reported in the English literature to date. Of significance is the fact that it carries a prognosis that is poor compared to other types of colorectal cancers. We report herein the cases of four patients with primary linitis plastica of the rectum who underwent surgery, followed by intensive postoperative chemotherapy using 5-fluorouracil (5-FU) derivatives in our institution. A review of the literature is presented with special reference to the diverse treatment and prognosis of this unusual disease. Although three of the patients died of recurrent cancer, one has survived for 5 years and 10 months despite advanced disease. This is only the third reported case of a patient with linitis plastica of the rectum achieving 5-year survival. We believe that this unexpected long survival could be related to the patient's extensive lymphadenectomy and intensive postoperative chemotherapy using cisplatin and 5-FU derivatives.

Cytochrome bd-type quinol oxidase in a mutant of Bacillus stearothermophilus deficient in caa3-type cytochrome c oxidase

Gram-positive thermophilic Bacillus species contain cytochrome caa3-type cytochrome c oxidase as a terminal oxidase in the respiratory chain. To identify alternative oxidases, we isolated B. stearothermophilus mutants defective in the caa3-type oxidase activity. One mutant contained little cytochrome a and had low cytochrome c oxidase activity. However, growth and the respiratory activity of membranes in the presence of NADH were close to normal, suggesting that the mutant contains an alternative electron transfer pathway. A novel oxidase was isolated from the membrane fraction of the mutant. The enzyme is a cytochrome bd-type quinol oxidase composed of two subunits of 52 and 40 kDa, whose N-terminal regions show sequence similarity to polypeptides of the bd-type oxidase from Escherichia coli and Azotobacter vinelandii. This is the first report of a bd-type terminal oxidase purified from a Gram-positive bacterium.

The importance of the real-time fluoroscopic intraoperative direct cholangiogram in the laparoscopic cholecystectomy using a new instrument

BACKGROUND/AIMS

Laparoscopic cholecystectomy (LC) has become an accepted standard operative technique for gallstone treatment worldwide. On the other hand, complications, such as bile duct injuries, have been reported recently with the expansion of indication for LC. Intraoperative cholangiogram (IOC), to minimize the risk of bile duct injury, is now considered to be essential for safe LC. There are disadvantages to IOC such as increased operating time, the possibility of bile duct injury and the difficulties of manipulation.

MATERIAL AND METHODS

We have developed a method for real-time fluoroscopic cholangiograms using a new instrument designed by our group for safe LC. First, a round-tip stylet is inserted through a sheath to coax it gently through the spiral valves of the cystic duct. Secondly, the stylet is removed and the cholangiogram catheter is inserted smoothly. Digital C-arm fluoroscopy provides "real-time" imaging of biliary tree. As a result, we became able to obtain a clear cholangiogram easily in a very short time.

RESULTS

In the first 136 patients, direct cholangiograms were attempted in 106 cases and successfully completed in 102 cases (96.2%).

CONCLUSION

With the development of real-time fluoroscopic intraoperative direct cholangiogram, we are able to cope with bile duct injuries and anomalies, and unsuspected bile duct stones.

Preoperative embolization of gastric arteries for esophageal cancer

BACKGROUND

We developed a novel treatment of preoperative embolization therapy in an attempt to prevent anastomotic leakage after esophageal resection. We report the results of this new treatment.

METHODS

Preoperative embolization therapy (PET) was performed in 24 cases of esophageal carcinoma. The femoral artery was punctured, and celiac angiography was performed. The left gastric artery and splenic artery underwent embolization. The right gastric artery then underwent embolization at a site beyond the second or third branch to the gastric wall. With a laser flow meter the stomach tissue blood flow was measured before and after construction of the gastric tube, and the change in blood flow was compared.

RESULTS

The average decrease in gastric blood flow was 23% in patients with PET and 65% in patients without PET. Twenty-one (88%) of 24 cases maintained more than 50% tissue blood flow in patients with PET and in 1 (8%) of 12 in patients without PET (p < 0.001 by t test). No serious complications occurred.

CONCLUSIONS

Preoperative embolization therapy is a safe and uncomplicated technique, and tissue blood flow in the stomach was better preserved. This new technique is expected to reduce the frequency of anastomotic leakage after esophageal operation.

Association between preoperative plasma CEA levels and the prognosis of gastric cancer following curative resection. Tumor Marker Committee, Japanese Foundation for Multidisciplinary Treatment of Cancer, Tokyo, Japan

A large-scale retrospective study was undertaken to evaluate the association between preoperative plasma carcinoembryonic antigen (CEA) levels and the prognosis of 2768 gastric cancer patients who underwent curative gastrectomy between 1983 and 1984 at 66 leading medical institutions in Japan Postoperative follow-up was at least 5 years. Preoperative plasma CEA levels were also analysed against other prognostic factors. Preoperative plasma CEA levels showed strong correlations to the degree of lymph node metastasis (P < 0.001), TNM stage (P = 0.004) and the histopathology of the gastric cancer (P < 0.001). Preoperative CEA levels were also evaluated against survival, after being adjusted for the effect of clinically important factors by multivariate analysis. Patients with lower preoperative plasma CEA levels survived significantly longer than patients with higher CEA levels (P = 0.0001). This analysis demonstrates that curatively resected gastric cancer patients with higher preoperative plasma CEA levels have a poorer prognosis than those with lower levels, despite the adjustment for the effects of major prognostic factors.

Prognostic value of preoperative immunosuppressive acidic protein in patients with gastric carcinoma. Findings from three independent clinical trials. Tumor Marker Committee for the Study Group of Immunochemotherapy with PSK for Gastric Cancer

BACKGROUND

Immunosuppressive acidic protein (IAP) has been reported to have close correlation with the impairment of host immune response. To evaluate the significance of IAP in clinical studies, the prognostic value of preoperative IAP was investigated in clinical trials of patients with gastric carcinoma after curative resection.

METHODS

An appropriate IAP threshold value of 580 micrograms/mL was determined using Cox's proportional hazards model. Five-year survival rates were estimated for high and low IAP groups in three different clinical studies. Meta-analysis was performed based on individual patient data, and summarized hazard ratios were estimated using a stratified proportional hazards model.

RESULTS

Meta-analysis of the three clinical trials demonstrated that patients with preoperative IAP levels above the threshold had significantly poorer cancer related survival (P = 0.0039) and absolute survival (P = 0.0023), even after adjustment for the major prognostic factors.

CONCLUSIONS

Gastric carcinoma patients with an IAP value above the threshold level of 580 micrograms/mL have a higher risk of cancer death and absolute death than patients with an IAP value below the threshold value.