The impact of biliary stents on the diagnostic yield of endoscopic ultrasound-guided fine needle aspiration for solid pancreatic lesions: A single-center retrospective study and meta-analysis

Background

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is widely used for the pathological diagnosis of solid pancreatic lesions but in cases with obstructive jaundice, transpapillary sampling can be performed during endoscopic retrograde cholangiopancreatography with transpapillary biliary stent placement. Thus, it is still controversial whether EUS-FNA should be performed prior to endoscopic retrograde cholangiopancreatography with biliary stent placement or only after negative transpapillary sampling.

Methods

The accuracy, sensitivity, and specificity of EUS-FNA for solid pancreatic lesions with or without indwelling biliary stents were retrospectively studied in patients undergoing EUS-FNA between January 2017 and December 2021. We also conducted a meta-analysis including our data to compare the accuracy and sensitivity of EUS-FNA with or without biliary stents.

Results

A total of 509 patients (40 with biliary stents and 469 without biliary stents) were included. The accuracy (77.5% vs. 94.5%, p < 0.001) and sensitivity (71.0% vs. 91.7%, p < 0.001) were lower in EUS-FNA with biliary stents. A meta-analysis confirmed that accuracy (odds ratio [OR] of 0.43, 95% confidence interval [CI] 0.29-0.62, p < 0.001) and sensitivity (OR of 0.46, 95% CI 0.33-0.64, p < 0.001) were lower in EUS-FNA with biliary stents. There were no statistically significant differences between plastic stents and self-expandable metallic stents for accuracy or sensitivity.

Conclusions

The presence of biliary stents had a negative impact on the diagnostic performance of EUS-FNA, and EUS-FNA prior to endoscopic retrograde cholangiopancreatography with biliary stent placement should be considered in cases with obstructive jaundice.

Feasibility of comprehensive genomic profiling using endoscopic ultrasound-guided tissue acquisition with a 22-gauge Franseen needle

Aim

Comprehensive genomic profiling (CGP) test for solid tumors is now increasingly utilized in clinical practice, especially in pancreatobiliary cancer, and specimens obtained by endoscopic ultrasound-guided tissue acquisition (EUS-TA) are often submitted for tissue-based CGP test. In this study, we evaluated the feasibility of EUS-TA using a 22-gauge Franseen needle for the CGP test.

Methods

Consecutive patients with solid tumors who underwent EUS-TA using a 22-gauge Franseen needle, and whose tissue samples were pre-checked for suitability for CGP test, were included in this single-center, retrospective analysis. The success rates of appropriate sample collection for CGP evaluated by pathologists (1st quality control) and CGP test (2nd quality control) were evaluated. In addition, The EUS-TA slides were evaluated for the tissue area and tumor area content, using the image software.

Results

A total of 50 cases, with 78% of pancreatic cancer, were included in the analysis. A median of 3 passes of EUS-TA were performed with an adverse event rate of 4%. The success rates for 1st and 2nd quality control for CGP tests were 86% and 76%, respectively. The image analyses suggested EUS-TA specimen did not always fulfill CGP test criteria, with 18% of tissue area ≥16 mm2 and 38% of tumor area content ≥20%, even in cases with successful CGP tests. The suction method yielded a significantly larger amount of DNA but without a significant difference in the multivariate analysis.

Conclusions

The present study demonstrated the feasibility of EUS-TA using a 22-gauge Franseen needle for CGP test.

Retrospective comparative study of new slim-delivery and conventional large-cell stents for stent-in-stent methods for hilar malignant biliary obstruction

OBJECTIVES

Endoscopic management of unresectable hilar malignant biliary obstruction (HMBO) is technically challenging, and effectiveness of stent-in-stent using large-cell, metal stents was reported. A new, large-cell stent with a 6F tapered delivery system was recently developed. The aim of this study was to compare clinical outcomes of slim-delivery and conventional large-cell stents.

METHODS

This was a multicenter retrospective comparative study of stent-in-stent methods using slim-delivery stents (Niti-S Large Cell SR Slim Delivery [LC slim-delivery]) and conventional stents (Niti-S large-cell D-type; LCD) for unresectable HMBO.

RESULTS

Eighty-three patients with HMBO were included; 31 LC slim-delivery and 52 LCD. Overall technical and clinical success rates were 100% and 90% in LC slim-delivery group and 98% and 88% in LCD group. Use of the LC slim-delivery was associated with shorter stent placement time in the multiple regression analysis, with a stent placement time of 18 and 23 min in LC slim-delivery and LCD groups, respectively. The early adverse event (AE) rate of LC slim-delivery was 10%, with no cholangitis or cholecystitis as compared to 23% in the LCD group. Recurrent biliary obstruction (RBO) rates and time to RBO were comparable between the two groups: 35% and 44%, and 8.5 and 8.0 months in LC slim-delivery and LCD groups, respectively. The major cause of RBO was tumor ingrowth (82%) in the LC slim-delivery group and sludge (43%) and ingrowth (48%) in LCD group.

CONCLUSION

Stent-in-stent methods using LC slim-delivery shortened stent placement time with low early AE rates and comparable time to RBO in patients with HMBO.

Skeletal muscle status and survival among patients with advanced biliary tract cancer

BACKGROUND

Studies have demonstrated a prognostic role of sarcopenia (i.e., loss of skeletal muscle volume and functionality) in patients with various cancer types. In patients with biliary tract cancer, the quantity and quality of skeletal muscles and their serial changes have not been fully investigated in relation to survival outcomes.

METHODS

We identified 386 patients with unresectable or recurrent biliary tract cancer and calculated skeletal muscle index (SMI) and skeletal muscle density (SMD) to estimate muscular quantity and quality, respectively, based on computed tomography images. Using the Cox regression model with adjustment for potential confounders, we calculated hazard ratios (HRs) and 95% confidence intervals (CIs) for progression-free survival (PFS) and overall survival (OS) according to skeletal muscle status and its serial change.

RESULTS

Compared to patients without sarcopenia, patients with sarcopenia were associated with shorter PFS (multivariable HR, 1.60; 95% CI, 1.15-2.22; P = 0.005), but not with OS (P = 0.027) at the adjusted α level of 0.013. SMD at baseline was associated with OS (multivariable HR comparing the extreme quartiles, 1.52; 95% CI, 1.07-2.14; Ptrend = 0.012), but not with PFS (Ptrend = 0.13). A reduction in SMI rather than that in SMD was associated with OS. Progressive disease was a risk factor for reductions in SMI and SMD.

CONCLUSIONS

Skeletal muscle quantity and quality and their serial changes were associated with survival outcomes in patients with advanced biliary tract cancer. Our data highlight the importance of designing nutritional and physical interventions for improvements in skeletal muscle status.

Kluyvera georgiana Bacteremia Due to Acute Cholangitis: A Report of the First Known Case and a Literature Review

We herein present the first known case of bacteremia caused by Kluyvera georgiana in a 67-year-old female undergoing chemotherapy for recurrent pancreatic cancer. The patient underwent choledochojejunotomy and thereafter developed ascending cholangitis. The diagnosis of K. georgiana was confirmed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. A literature review of Kluyvera spp. infections indicated potential risk factors including an underlying malignancy and immunosuppression. Although Kluyvera spp. infections are typically sensitive to antibiotics, multidrug resistance is possible. This case highlights the importance of the early diagnosis and treatment of K. georgiana and its associated risk factors.

Clinical trajectory of intraductal papillary mucinous neoplasms progressing to pancreatic carcinomas during long-term surveillance: a prospective series of 100 carcinoma cases

BACKGROUND

Trajectories of serological and morphological signatures have not been documented in pancreatic carcinogenesis related to intraductal papillary mucinous neoplasms (IPMNs).

METHODS

Using a prospective cohort of 3437 IPMN patients, we identified 100 IPMN patients who developed pancreatic carcinomas during long-term surveillance. We examined serial changes of blood markers (carbohydrate antigen 19-9 [CA19-9], hemoglobin A1c [HbA1c], and pancreatic enzymes) and morphological features (worrisome features and high-risk stigmata) during the prediagnostic period of pancreatic carcinomas, overall and by carcinoma types (IPMN-derived vs. concomitant pancreatic carcinomas).

RESULTS

CA19-9 elevation was observed in 39 patients and was associated with a metastatic stage. Compared to IPMN-derived carcinomas, concomitant carcinomas were more likely to represent CA19-9 elevation (60% vs. 30%, respectively; P = 0.005). HbA1c levels elevated only in 3 patients. Pancreatic enzyme elevation was observed in 18 patients with no differences in frequencies between the carcinoma types. All patients with elevated levels of blood markers had positive findings on cross-sectional imaging. High-risk stigmata or worrisome features were observed in all patients but one with concomitant carcinoma. The most common types of worrisome features were the main pancreatic duct dilatation and CA19-9 elevation in IPMN-derived and concomitant carcinomas, respectively. Compared to IPMN-derived carcinomas, concomitant carcinomas were less likely to harbor high-risk stigmata (16% vs. 86%, respectively; P < 0.001).

CONCLUSIONS

The usefulness of currently available blood biomarkers was limited in early detection of pancreatic carcinomas related to IPMNs. Morphological alterations were well correlated with long-term risk of IPMN-derived carcinomas, but not with that of concomitant carcinomas.

Second Covered and Uncovered Self-Expandable Metal Stents for Recurrent Gastric Outlet Obstruction: A Retrospective Comparative Study

Background: Endoscopic self-expandable metal stent (SEMS) placement is a current mainstay for malignant gastric outlet obstruction (GOO), but symptomatic recurrence due to initial SEMS dysfunction commonly occurs. We aimed to compare the safety and effectiveness of second SEMS for recurrent GOO (RGOO). Methods: Between April 2006 and December 2022, a total of 95 cases with malignant RGOO undergoing second endoscopic SEMS placement were enrolled. Technical and clinical success rates, RGOO, time to RGOO (TRGOO), stent patency rate, adverse events (AE), and overall survival (OS) were retrospectively compared between covered and uncovered SEMS (cSEMS/uSEMS) groups. Risk factors for TRGOO were also explored. Results: Baseline characteristics were well balanced between cSEMS (n = 48) and uSEMS (n = 47) groups, except for the causes of the initial SEMS dysfunction. High technical and clinical success rates with a similar incidence of AE (15% vs. 17%, p = 0.78) and OS (median of 101 vs. 102 days, p = 0.68) were achieved in both groups. There were no statistical differences in cumulative incidence of RGOO (19% vs. 13%, p = 0.58), TRGOO (median, not reached in both groups, p = 0.57), and stent patency rates at 1, 2, and 3 months between the groups (60%, 47% and 26%, respectively vs. 70%, 55% and 38%, respectively). However, TRGOO tended to be longer in cSEMS in cases with RGOO due to tumor ingrowth (median, not reached vs. 111 days, p = 0.19). A Cox regression analysis demonstrated that chemotherapy after second SEMS placement was significantly associated with an improved TRGOO (the hazard ratio of 0.27 [95% confidence interval, 0.08-0.93], p = 0.03). Conclusions: Regardless of the type of SEMS, second SEMS placement was similarly safe and effective for RGOO. The type of second SEMS might be considered based on the cause of initial SEMS dysfunction.

Application of MinION Amplicon Sequencing to Buccal Swab Samples for Improving Resolution and Throughput of Rumen Microbiota Analysis

The Illumina MiSeq platform has been widely used as a standard method for studying the rumen microbiota. However, the low resolution of taxonomic identification is the only disadvantage of MiSeq amplicon sequencing, as it targets a part of the 16S rRNA gene. In the present study, we performed three experiments to establish a high-resolution and high-throughput rumen microbial profiling approach using a combination of MinION platform and buccal swab sample, which is a proxy for rumen contents. In experiment 1, rumen contents and buccal swab samples were collected simultaneously from cannulated cattle (n = 6) and used for microbiota analysis using three different analytical workflows: amplicon sequencing of the V3–V4 region of the 16S rRNA gene using MiSeq and amplicon sequencing of near full-length 16S rRNA gene using MinION or PacBio Sequel II. All reads derived from the MinION and PacBio platforms were classified at the species-level. In experiment 2, rumen fluid samples were collected from beef cattle (n = 28) and used for 16S rRNA gene amplicon sequencing using the MinION platform to evaluate this sequencing platform for rumen microbiota analysis. We confirmed that the MinION platform allowed species-level taxa assignment for the predominant bacterial groups, which were previously identified at the family- and genus-level using the MiSeq platform. In experiment 3, buccal swab samples were collected from beef cattle (n = 30) and used for 16S rRNA gene amplicon sequencing using the MinION platform to validate the applicability of a combination of the MinION platform and buccal swab samples for rumen microbiota analysis. The distribution of predominant bacterial taxa in the buccal swab samples was similar to that in the rumen samples observed in experiment 2. Based on these results, we concluded that the combination of the MinION platform and buccal swab samples may be potentially applied for rumen microbial analysis in large-scale studies.

Corticosteroid-induced Kaposi's Sarcoma Revealed by Severe Anemia: A Case Report and Literature Review

We herein report a case of gastrointestinal (GI) Kaposi's sarcoma (KS) without cutaneous involvement in a 73-year-old man who had received immunosuppressive drugs for granulomatosis with polyangiitis. After one year of prednisolone use, he presented with tarry stool and severe anemia. Endoscopic and pathological examinations revealed bright-reddish protruding lesions with proliferating spindle cells positive for D2-40, CD34, and HHV-8, which are definitively diagnostic of GI-KS. Drug-induced KS without HIV infection or transplantation is extremely rare, and its clinical features remain unknown. Therefore, we conducted a literature review of steroid-induced KS.

Mental health of gatekeepers may influence their own attitudes toward suicide: A questionnaire survey from a suicide-prevention gatekeeper training program

AIMS

We aimed to investigate the association between general mental health and attitudes toward suicide of participants in suicide-prevention gatekeeper training programs.

METHODS

We conducted a number of half day training seminars within a suicide prevention program addressing gatekeepers. Participants filled in two questionnaires, one measuring general health (General Health Questionnaire, GHQ-12), and one measuring attitudes towards suicide (ATTS).

RESULTS

The total sample size of participants was 230, of whom 115 completed questionnaires. There were no significant differences in demographic backgrounds between the good mental health (GHQ-12 ≤ 4) and the poor mental health (GHQ-12 ≥ 5) groups. The poor mental health group was more likely to think that people have the right to commit suicide.

CONCLUSION

There was a difference in attitudes toward suicide between the good mental health and the poor mental health groups, indicating that attention should be paid to participants' mental health when conducting suicide-prevention gatekeeper training.

How perceived social support relates to suicidal ideation: a Japanese social resident survey

BACKGROUND

The loss of social support is one of the major risk factors for suicide. However, there are few empirical studies that have examined how a person's suicide ideation relates to their social support.

AIMS

To examine the relationship between social support and suicidal ideation.

METHODS

Self-report questionnaires were sent to 2,200 randomly selected adults in Japan. The questionnaire inquired the participants about the severity of suicidal ideation, the details of current perceived social support and their degree of satisfaction with this social support. Social support and related indicators were compared among three groups of participants that varied in severity of suicidal ideation.

RESULTS

People in the group that had suicide ideation during their lives reported receiving significantly less support from their family and had greater feelings of dissatisfaction with that support than those in the other groups. Furthermore, people who had suicide ideation during the month immediately preceding the survey reported providing less support to their family, relatives or friends, as well as receiving less support from family than other groups, and having stronger feelings of dissatisfaction with social support.

CONCLUSION

Our study identified a strong relationship between the severity of suicidal ideation and perceived social support.

Network analysis for motives in suicide cases: a cross-sectional study

AIM

Suicide victims have various distresses or motives. There are few studies on how these motives toward suicide relate with each other. We used network analyses to extract the structures of correlations among the motives for suicide.

METHODS

We obtained datasets of suicide victims from 2007-2009 in Japan in cooperation with Ibaraki Prefectural Police Headquarters. The data were analyzed by network centrality measures and a structural analysis by block modeling.

RESULTS

Among the motives, depression and physical illness showed relatively high scores of 'degree centrality', whereas depression and unemployment showed relatively high scores of 'betweenness centrality'. Structural analysis by block modeling resulted in eight blocks. The most important block comprised eight motives, including conflict between parent and child, marital conflict, economic hardship, and overloaded with debt.

CONCLUSION

Depression and physical illness were important and priority areas for completed suicides, although these two motives had different influences on suicide behaviors. Furthermore, structural analysis revealed the important role of a block, including some familial and financial motives, which induced hopelessness. Our results suggest that it might be useful to consider the common ways in which motivations for suicide are tied together when suicide intervention is launched from a social model point of view.

[A case of Brugada syndrome with convulsive seizure during antidepressant administration: relation of antidepressant agents and arrhythmia leading to sudden death]

Brugada syndrome is an arrhythmogenetic disease characterized by electrocardiographic ST segment elevation in right precordial leads, which is called "coved type", and an increased risk of sudden death as the result of ventricular fibrillation. We presented a case of Brugada syndrome with a convulsive seizure, during administration of a tricyclic antidepressant for the treatment of a depressive state. A 43-year-old man with bipolar II disorder and obsessive-compulsive disorder was admitted to our hospital for the treatment of a depressive state. There was no medical history of heart failure. Nortriptyline was effective for his depressive as well as for obsessive symptoms. During the treatment, however, he presented a convulsive syncope. Electrocardiography (ECG) showed "coved type" ST segment elevation, and the patient consulted a cardiologist. Electrophysiological study revealed Brugada syndrome, and an implantable cardioverter defibrillator was placed. An overdose of antidepressants has been reported to produce a Brugada-type ECG because of its Na channel antagonism. However, in the present case, the abnormal ECG findings occurred following a usual dosage of nortriptyline. Thus, it is suggested that Brugada syndrome is related to a susceptibility to antidepressants in the present case. Every psychiatrist managing antidepressant therapy should be aware of Brugada syndrome and this ECG pattern, which may be a marker of sudden death.

Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and coplanar polychlorinated biphenyls in human milk in Osaka City, Japan

Forty-eight human milk samples were collected from primiparous mothers in Osaka City from June 1999 to January 2000 and analyzed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like coplanar polychlorinated biphenyls (CoPCBs). Mean toxic equivalents (TEQs) in the milk were 13.86 pg I-TEQ/g fat or 16.50 pg World Health Organization (WHO)-TEQ/g fat for PCDDs and PCDFs; 9.87 pg WHO-TEQ/g fat for CoPCBs; and 23.74 pg TEQ/g fat using I-TEQ values of PCDDs and PCDFs or 26.36 pg TEQ/g fat using WHO-TEQ values of PCDDs and PCDFs for total PCDDs, PCDFs, and CoPCBs. The TEQ levels of these chemicals in human milk in Osaka City were in the range of levels in human milk surveyed in Japan, but the TEQ levels of PCDDs and PCDFs and total PCDDs, PCDFs, and CoPCBs from our study were slightly higher than average TEQ levels in human milk in Japan. When comparing our data with the latest data from the United States and some European countries, the TEQ levels of PCDDs and PCDFs in human milk from Osaka City were relatively high, whereas those of CoPCBs were ranked as being of intermediate level. Only TEQ values of CoPCBs in human milk were found to correlate with the increasing age of mothers and their estimated intake of seafood during the year before pregnancy. Concentrations of PCBs 105 and 118 contributed to TEQ values of CoPCBs associated with seafood intake, whereas those of PCBs 156, 157, 114, 189, 167, and 169 contributed to TEQ values of CoPCBs associated with increasing maternal age.

Effects of cysteine on the cytotoxicity of arsenic compounds

Effects of cysteine on the cytotoxicity of arsenic compounds, such as arsenite, arsenate, methylarsonic acid (MMA), and dimethylarsinic acid (DMA), were investigated in cultured human HL-60 cells. Using adenosine triphosphate bioluminescence assay, the rank order of the mixtures of arsenicals with cysteine was: DMA > arsenite > arsenate > MMA. The IC50 of DMA with equimolar cysteine was approximately 7.7 microM, nearly two orders of magnitude lower than that of DMA alone. Apoptotic cells were examined by the TUNEL method, and cysteine was found to enhance the induction of apoptosis by arsenicals. Using LC-ICP-MS, trivalent arsenic was detected in the mixtures of arsenate, DMA, and MMA with cysteine. These results suggested that the trivalent arsenic in the mixtures of arsenicals with cysteine might account for the enhanced cytotoxicity as well as apoptosis, and that cysteine is involved in induction of the adverse effects of arsenicals in humans.

Genotoxicity of gardenia yellow and its components

Gardenia fruit (Gardenia jasminoides ELLIS) is widely used as a natural food colorant and as a traditional Chinese medicine for treatment of hepatic and inflammatory diseases. "Gardenia yellow" is a natural food colorant which is extracted by ethanol from gardenia fruit. The purpose of this study was to evaluate the genotoxicity of gardenia yellow. Genotoxicity of gardenia yellow and its components, crocetin, gentiobiose (a component of crocin), geniposide and genipin (formed by hydrolysis of geniposide), was studied by Ames test, rec-assay, and sister chromatid exchange (SCE) using V79 cells. Gardenia yellow and its components were found not to be mutagenic in the Salmonella reverse mutation assay. Gardenia yellow and genipin caused damage of DNA in rec-assay. Gardenia yellow induced a significant dose-dependent increase of SCE frequency (8.6 times at 1000 microg/ml as the value for the solvent control). Only genipin induced SCEs significantly among the components of gardenia yellow. Moreover, genipin induced a significant increase of tetraploids at all doses tested (95% at 8 microg/ml). Gardenia yellow preparation was analyzed by capillary electrophoresis (CE), and geniposide was detected. However, genipin was not observed. In conclusion, we have shown that genipin possesses genotoxicity. Furthermore, there were unidentified genotoxicants in gardenia yellow.

Simultaneous detection and removal of organomercurial compounds by using the genetic expression system of an organomercury lyase from the transposon Tn MERI1

Using a newly identified organomercury lyase gene (merB3) expression system from Tn MERI1, the mercury resistance transposon first found in Gram-positive bacteria, a dual-purpose system to detect and remove organomercurial contamination was developed. A plasmid was constructed by fusing the promoterless luxAB genes as bioluminescence reporter genes downstream of the merB3 gene and its operator/promoter region. Another plasmid, encoding mer operon genes from merR1 to merA, was also constructed to generate an expression regulatory protein, MerR1, and a mercury reductase enzyme, MerA. These two plasmids were transformed into Escherichia coli cells to produce a biological system that can detect and remove environmental organomercury contamination. Organomercurial compounds, such as neurotoxic methylmercury at nanomolar levels, were detected using the biomonitoring system within a few minutes and were removed during the next few hours.

Bio-affecting mercury detection using mercury resistance gene module fused with bioluminescence reporter genes

Bioluminescence sensor systems were developed for monitoring environmental mercury contamination. The biological mercury measurement sensor systems were constructed by DNA recombination technique. A bacterial mercury-resistant operon (meroperon) from Pseudomonas sp. K-6y4 and a bacterial bioluminescence operon (lux operon) from an ocean bacterium Vibrio fischeri were fused in avector plasmid. The resulting recombinant plasmids were cloned in Escherichia coli cells. The bioluminescence sensor systems responded to mercury chloride of 0.1 nM to 100 nM. The mercury bioluminescence sensor developed in this study can be used for monitoring of the bio-affecting mercury instead of total mercury that is measured by conventional analytical equipment. The fundamental feature of the bioluminescence sensor system is attractive for use as a monitoring system for bio-affecting environmental mercury contamination.

Evaluation of ppk-specified polyphosphate as a mercury remedial tool

To evaluate the utility of polyphosphate kinase gene (ppk)-specified polyphosphate in mercury remediation, a fusion plasmid, pMK27, with ppk from Klebsiella aerogenes and mercury transport genes, merT and merP, from Pseudomonas K-62, was constructed. The transcription and translation of ppk, merT and merP were found to be mercury-inducible. The ppk-specified polyphosphate was identified in cells preinduced by Hg2+, but not in cells without mercury induction, suggesting that the synthesis of polyphosphate is regulated by merR. The hypersensitive phenotype to Hg2+, shown by bacteria with pMRD141, which contains merT and merP, was almost completely restored to its original levels when the ppk was introduced into the plasmid, suggesting that the Hg2+-toxicity was reduced by the polyphosphate, probably via chelation formation. Bacteria with pMK27 accumulated approximately 6-fold more mercury than the bacteria with cloning vector, pUC119. These results clearly demonstrate that the polyphosphate is capable of retaining mercury in the cells without taxing the cells. Based on the results obtained in the present study, the fusion plasmid pMK27 may serve as a strategy for mercury remediation.

Sampling methods and residential factors affecting formaldehyde concentration in indoor air

Formaldehyde (HCHO) is the most serious residential pollutant. In order to evaluate residential HCHO levels, two sampling methods have been recommended; one is a 30 minute sampling in a closed room, and the other is a 24 hour sampling with an ordinary lifestyle routine. The aim of this report was to clarify the difference between the HCHO levels obtained by the two sampling methods. Residential air in 58 rooms was sampled for 30 minutes by an active sampling method more than 5 hours after residents closed windows, and by a passive sampling method for 24 hours with an ordinary lifestyle routine. The HCHO concentration with the 30 minute sampling was 0.118+/-0.065 ppm (range: 0.034-0.295 ppm) and 36 rooms (62%) exceeded the Japanese guideline value of 0.08 ppm, while 5% were higher than 0.25 ppm. The HCHO concentration with the 24 hours sampling was 0.053+/-0.039 ppm (range: 0.02-0.167 ppm) and only 13 rooms (22%) exceeded 0.08 ppm. The relationship between the concentrations obtained by the two methods was linear. However, the level with the 24 hour sampling significantly reduced with prolonged window opening time, meaning that occupants made an effort to reduce the usual exposure to about 40% of the exposure in a closed room by opening windows in order to escape from irritation. Since major adverse effects of HCHO are irritation and sensitization, the occasional peak concentration must be focused. In order to evaluate residential HCHO levels, measurement in a closed room is recommended even if people are living there.

The index of motor current amplitude has feasibility in control for continuous flow pumps and evaluation of left ventricular function

The index of motor current amplitude (ICA) has feasibility in continuous-flow ventricular assist device control. It can demonstrate the safe range of pump speed, which exists between the starting point of total assistance (t-point) and the starting point of sucking (s-point). The objective of this study was to investigate how the ICA characteristic curve changes with each condition of contractility, preload, and afterload changes. We changed preload, afterload, and contractility of closed-mock circulation and plotted the change of the ICA value against pump speed. Then the shift of ICA characteristic curve against the change of each condition was considered. When preload increased, ICA characteristic curves showed the expansion of a safe range. When afterload increased, ICA characteristic curves were shifted to the high rotation side, slightly narrowing a safe range. When contractility increased, ICA characteristic curves showed the shift of a convex above to narrowing of a safe range. As these shift patterns were observed even when the driving conditions of a circuit changed, reproducibility was checked. Understanding the feature of a shift pattern of ICA characteristic curves correctly, a possibility that change of the heart function could be predicted by change of ICA value and a possibility for a flexible control method based on ICA, according to hemodynamic state, were suggested.

Serum uric acid and the risk for hypertension and Type 2 diabetes in Japanese men: The Osaka Health Survey

OBJECTIVE

To investigate the association of serum uric acid level with the risk for hypertension and Type 2 diabetes.

DESIGN

Prospective cohort study.

SETTING

Work site in Osaka, Japan.

PARTICIPANTS

A total of 6,356 Japanese men, aged 35-60 years with systolic blood pressure < 140 mmHg and diastolic blood pressure < 90 mmHg, normal glucose intolerance, and no history of hypertension or diabetes at baseline.

MAIN OUTCOME MEASURES

Blood pressure was measured by standard techniques, using 160/95 mmHg for diagnosis of hypertension. Type 2 diabetes was defined as a fasting plasma glucose level > or = 126 mg/dl or a 2 h post-loaded plasma glucose level > or = 200 mg/dl.

RESULTS

During the 61,716 person-years follow-up period, we confirmed 639 cases of hypertension and 454 cases of Type 2 diabetes. Serum uric acid level was associated with an increased risk for hypertension but not for Type 2 diabetes. After adjustment for known risk factors, including daily alcohol consumption, the serum uric acid level was associated with an increased risk for hypertension; the relative risks for hypertension were 1.00 for quintile 1 of the serum uric acid level, 1.24 [95% confidence interval (CI), 0.94-1.65] for quintile 2, 1.34 (CI, 1.03-1.76) for quintile 3, 1.76 (CI, 1.35-2.29) for quintile 4, and 2.01 (CI, 1.56-2.60) for quintile 5 (P for trend < 0.001). Even among both non-drinkers and lean subjects, serum uric acid level was associated with an increased risk for hypertension.

CONCLUSIONS

Serum uric acid level was associated with an increased risk for hypertension but not for Type 2 diabetes.

Simple and rapid determination of Gtpase activity by capillary electrophoresis without radioisotope

In order to determine guanosine-5'-triphosphatase (GTPase) activity, we developed a simple, rapid and reliable method that utilizes capillary electrophoresis without radioisotope. Tubulin-GTPase was used for simple measurement of GTPase activity utilizing capillary electrophoresis. Tubulin, a component of microtubules, was incubated with guanosine-5'-triphosphate (GTP) in 100 mM 2-(N-morpholino) ethanesulfonic acid (MES) buffer (pH 6.5). Guanosine-5'-diphosphate (GDP) was determined as the hydrolyzed product of GTP. Guanosine-5'-monophosphate, GDP and GTP in the filtrate of the mixture were clearly separated using 10 mM MES buffer (pH 6.5) (migration time, 3.8, 5.5 and 7.2 minutes, respectively) with a fused-silica capillary column. The quantification of GDP was based on the peak area, which increased linearly with the concentration of GDP from 1 to 50 microM (r2=0.995). The peak area and migration time had good reproducibility; the intra-assay coefficient of variation (n=6) was 1.3% for peak area and 0.6% for migration time. As an application of this method, we examined the effect of dimethylarsinic acid, an effective antimitotic agent, on tubulin-GTPase. Dimethylarsinic acid inhibited tubulin-GTPase activity in a dose-dependent manner. The inhibition was not complete and the maximum decrease of the activity was about 50% at 200 microM dimethylarsinic acid. Thus, since this method is clean, simple and rapid, its application to the study of various GTPase proteins is expected to be useful.

Control strategy for biventricular assistance with mixed-flow pumps

A left ventricular assist device (LVAD) is an effective method to rescue severe heart failure. Although some require a biventricular assist, the control method for the biventricular assist device (BVAD) with a rotary pump is rarely shown. The objective of this study was to investigate the strategy for controlling BVAD with rotary pumps by in vivo studies. Using 5 piglets, we set a BVAD through a left thoracotomy and made global ischemia for 30 min by clamping the base of the ascending aorta. After unclamping, the analysis of pumping performance acted for 6 h reperfusion. We set the target flow of the LVAD and set the right ventricular assist device (RVAD) speed limit as less than when the atrial collapse occurs. To detect the ventricular collapse without any specific sensor, we calculated the index of current amplitude from motor current waveform and simultaneous mean current value. In all cases, over 6 h of observation was performed, and the RVAD was weaned almost automatically.

Sensorless controlling method for a continuous flow left ventricular assist device

We originated a novel control strategy for a continuous flow left ventricular assist device (LVAD). We examined our method by acute animal experiments to change the left ventricular (LV) contractility or LV end-diastolic pressure (LVEDP). To estimate the pump pulsatility without any specific sensor, we calculated the index of current amplitude (ICA) from motor current waveform. The ICA had a peak point (t-i point) that corresponded closely with the turning point from partial to total assistance, and a trough (s-i point) that corresponded with the beginning point of ventricular collapse. The pump flow at the t-i point (Qt-i) had no component of flow regurgitation. In the evaluation of the effects of preload LVEDP, afterload (mAoP), and contractility (max LV dp/dt), we found that preload was the only parameter that significantly influenced Qt-i. We concluded that our method could well control continuous flow LVAD by preventing reversed flow and ventricular collapse.

Determination of histamine, 1-methylhistamine and N-methylhistamine by capillary electrophoresis with micelles

Urinary histamine and Ngamma-methylhistamine (1-MH), a histamine metabolite, are highly correlated with histamine in plasma. Therefore, allergic reactions can be examined by determination of histamine and 1-MH in urine. We separated histamine, 1-MH and Nalpha-methylhistamine (N-MH) by capillary electrophoresis with UV detection at 210nm, using borate buffer (pH 9) containing 100 mM SDS. The absolute detection limits were 200, 100 and 50 pg for histamine, 1-MH and N-MH, respectively. To purify histamine 1-MH and N-MH in urine, a silica cartridge was used. Recovery rates of histamine, 1-MH and N-MH in physiological saline were 90.0, 91.4 and 95.4%, respectively. We measured histamine and 1-MH levels in urine from a normal female volunteer before and after a meal, and a male bronchial asthma patient. The results showed clearly that the concentrations of histamine and its metabolite rose after eating or asthma attack. N-MH was not detected in the urine.

Leisure-time physical activity at weekends and the risk of Type 2 diabetes mellitus in Japanese men: the Osaka Health Survey

AIMS

To investigate association between leisure-time physical activity at weekends and the risk of developing Type 2 diabetes mellitus (DM).

METHODS

Prospective examination of 6,013 Japanese men aged 35-60 years who were free of DM, impaired fasting glycaemia, or hypertension at study entry. Type 2 DM was defined by a fasting plasma glucose level > or = 7.0 mmol/l or a 2-h post-load plasma glucose level > or =11.1 mmol/l. Data on physical activity obtained from questionnaires consisted of overall leisure-time physical activity weekly and leisure-time physical activity at weekends.

RESULTS

During the 59,966 person-years follow-up, 444 cases developed Type 2 DM. Regular physical exercise at least once a week was associated with a reduced risk of Type 2 DM. After adjustments for age, body mass index, daily alcohol consumption, smoking habits, blood pressure levels and a parental history of Type 2 DM, men who engaged in regular physical exercise at least once a week had a relative risk of Type 2 DM of 0.75 (95% CI, 0.61-0.93) compared with men engaging in exercise less often. Even vigorous activity only once a week at weekends was associated with a reduced risk of Type 2 DM. Men who engaged in vigorous activity at least once a week at weekends had a multiple-adjusted relative risk of Type 2 DM of 0.55 (95% CI, 0.35-0.88) compared with sedentary men.

CONCLUSIONS

Regular physical exercise at least once a week and vigorous activity even only once a week at weekends are associated with a decreased risk of Type 2 DM.

Identification of three merB genes and characterization of a broad-spectrum mercury resistance module encoded by a class II transposon of Bacillus megaterium strain MB1

The complete structure of a broad-spectrum mercury resistance module was shown by sequencing the Gram-positive bacterial transposon TnMERI1 of Bacillus megaterium MB1. The regions encoding organomercury resistance were identified. Upstream of a previously identified organomercurial lyase merB (merB1) region of TnMERI1, a second merR (merR2) and a second merB gene (merB2) were found. These genes constitute a second operon (mer operon 2) following a promoter/operator (P(merR2)) region. A third organomercurial lyase gene (merB3) was found immediately upstream of the mer operon (mer operon 1) followed by a promoter/operator (P(merB3)) region homologous to that of the mer operon 1 (P(merR1)-merR1-merE-like-merT-merP-merA). The complete genetic structure of the mercury resistance module is organized as P(merB3)-merB3-P(merR1)-merR1-merE-like-merT+ ++ -merP-merA-P(merR2)-merR2 -merB2-merB1. The subcloning analysis of these three merB genes showed distinct substrate specificity as different organomercury lyase genes.

Impact of cigarette smoking on the incidence of Type 2 diabetes mellitus in middle-aged Japanese men: the Osaka Health Survey

AIMS

To assess the impact of cigarette smoking on the incidence of Type 2 diabetes mellitus (DM) in middle-aged Japanese men.

METHODS

The study enrolled 6250 men aged 35-60 years and free of diabetes, impaired fasting glucose and hypertension at entry. Type 2 DM was defined by a fasting plasma glucose level > or =7.0 mmol/l or physician-diagnosed Type 2DM.

RESULTS

Four hundred and fifty cases of Type 2 DM were confirmed during the 60904 person-years follow-up. After adjustment for multiple covariates, including age, body mass index, alcohol consumption, physical activity, parental history of diabetes and the level of fasting plasma glucose, total cholesterol, triglycerides, high-density lipoprotein cholesterol and haematocrit, the relative risk of Type 2 DM among current smokers compared with non-smokers was 1.47 (95% confidence interval (CI) 1.14-1.92). Men who smoked >30 cigarettes/day had a multivariate-relative risk of 1.73 (95% CI 1.20-2.48) compared with non-smokers. The number of cigarettes smoked daily and the pack-year values were positively related to the development of Type 2 DM in a dose-dependent manner (P for trends = 0.0026 and 0.001, respectively).

CONCLUSIONS

A cigarette smoking habit is an independent risk factor for Type 2 DM.

High normal blood pressure, hypertension, and the risk of type 2 diabetes in Japanese men. The Osaka Health Survey

OBJECTIVE

To investigate the relationship between high normal blood pressure or hypertension and the risk of developing type 2 diabetes in a large Japanese cohort.

RESEARCH DESIGN AND METHODS

We enrolled 7,594 Japanese men aged 35-60 years who did not have diabetes or impaired fasting glucose at study entry. Type 2 diabetes was defined as a fasting plasma glucose level of > or = 126 mg/dl or a 2-h postload plasma glucose level of > or = 200 mg/dl. High normal blood pressure was defined as no history of hypertension and a systolic blood pressure of > or = 130 and < 140 mmHg or a diastolic blood pressure of > or = 85 and < 90 mmHg. Subjects were considered to have hypertension if they had a systolic blood pressure > or = 140 mmHg, if they had a diastolic blood pressure > or = 90 mmHg, or if they were taking anti-hypertensive medications.

RESULTS

We confirmed 600 cases of type 2 diabetes during the 72,946 person-years of follow-up. Both high normal blood pressure and hypertension were associated with the risk of type 2 diabetes. Compared with normotensive men, men with high normal blood pressure had a multiple adjusted relative risk (RR) of 1.39 (95% CI 1.14-1.69), and men with hypertension had a multiple adjusted RR of 1.76 (1.43-2.16). Even among lean men (BMI < 22.7 kg/m2), men with high normal blood pressure had a multiple adjusted RR of 1.71 (1.20-2.42), and men with hypertension had a multiple adjusted RR of 2.02 (1.34-3.05) compared with normotensive men.

CONCLUSIONS

High normal blood pressure and hypertension are associated with an increased risk of developing type 2 diabetes.

Daily alcohol consumption and the risk of type 2 diabetes in Japanese men: the Osaka Health Survey

OBJECTIVE

To investigate the relationship between daily alcohol consumption and the risk of type 2 diabetes in a large Japanese cohort.

RESEARCH DESIGN AND METHODS

We enrolled 6,362 Japanese men aged 35-61 years who did not have diabetes, impaired fasting glucose, hypertension, or liver cirrhosis at study entry. Type 2 diabetes was defined as a fasting plasma glucose (FPG) level > or =126 mg/dl or was diagnosed by a physician. Data on alcohol consumption were obtained from questionnaires. We confirmed 456 cases of type 2 diabetes during the 62,016 person-years of follow-up.

RESULTS

The relationship between daily alcohol consumption and the risk of type 2 diabetes among lean men and among men with a higher BMI was paradoxical. Among lean men (BMI < or =22.0 kg/m2), heavy drinking was associated with an increased risk of type 2 diabetes. Men who consumed > or =50.1 ml/day of alcohol had a relative risk (RR) of 2.48 (95% CI 1.31-4.71) compared with nondrinkers after adjusting for age, BMI, regular physical exercise, parental history of diabetes, smoking habits, and FPG level. However, among men with a BMI > or =22.1 kg/m2, moderate drinking (29.1-50.0 ml/day) was associated with a decreased risk of type 2 diabetes. Daily moderate drinkers had a multiple adjusted RR of 0.58 (0.39-0.87) compared with nondrinkers.

CONCLUSIONS

Among men with a BMI > or =22.1 kg/m2, moderate alcohol consumption was associated with a reduced risk of type 2 diabetes, but among lean men (BMI < or =22.0 kg/m2), heavy alcohol consumption was associated with an increased risk of type 2 diabetes.

Structure analysis of a class II transposon encoding the mercury resistance of the Gram-positive Bacterium bacillus megaterium MB1, a strain isolated from minamata bay, Japan

A unique transposon was found in the chromosome of Bacillus megaterium MB1, a Gram-positive bacterium isolated from mercury-polluted sediments of Minamata Bay, Japan. The transposon region of a 14.5kb DNA fragment was amplified by PCR using a single PCR primer designed from the nucleotide sequence of an inverted repeat of class II transposons. The molecular analysis revealed that the PCR-amplified DNA fragment encodes a transposition module similar to that of Tn21. The transposon also encodes a broad-spectrum mercury resistance region having a restriction endonuclease map identical to that of Bacillus cereus RC607, a strain isolated from Boston Harbor, USA. The result of a phylogenetic analysis of the amino acid sequence of putative resolvase of the transposon showed that the transposon is phylogenetically closer to the transposons of Gram-positive bacteria than those of Gram-negative bacteria. Besides the transposition module and mer operon, the transposon encodes a mobile genetic element of bacterial group II introns between the resolvase gene and mer operon. The intron, however, does not intervene in any exon gene. The discovery of this newly found combination of the complex mobile elements may offer a clue to understanding the horizontal dissemination of broad-spectrum mercury resistance among microbes.

Walking to work and the risk for hypertension in men: the Osaka Health Survey

BACKGROUND

It is not known whether physical activity is effective in reducing the risk for hypertension.

OBJECTIVE

To investigate the association of the duration of the walk to work and leisure-time physical activity with the risk for hypertension.

DESIGN

Prospective cohort study.

SETTING

Work site in Osaka, Japan.

PARTICIPANTS

6017 Japanese men 35 to 60 years of age with systolic blood pressure less than 140 mm Hg, diastolic blood pressure less than 90 mm Hg, normal glucose intolerance, and no history of hypertension or diabetes at baseline.

MEASUREMENTS

Data on physical activity were obtained by using questionnaires. Blood pressure was measured by using a standard technique; a value of at least 160/95 mm Hg was used to diagnose hypertension.

RESULTS

During 59,784 person-years of follow-up, 626 cases of hypertension were confirmed. The duration of the walk to work was associated with a reduction in the risk for incident hypertension; multivariate-adjusted relative risks were 1.00 for a walk of 10 minutes or less (reference category), 0.88 (95% CI, 0.75 to 1.04) for an 11- to 20-minute walk, and 0.71 (CI, 0.52 to 0.97) for a walk of 21 minutes or more (P for trend = 0.02). For every 26.3 men who walk more than 20 minutes to work, one case of hypertension will be prevented.

CONCLUSIONS

Walking to work and other types of physical activity decreased the risk for hypertension in Japanese men. Regular exercise can prevent hypertension.

Local coagulofibrinolysis in the postsurgical recovery of patients with chronic subdural haematoma

Postoperative recovery of patients with chronic subdural haematoma (CSH) was investigated by comparing pre- and postoperative coagulant and fibrinolytic activity in the haematoma contents of 15 patients with SCH. Patients in this study were treated draining the haematoma cavity without irrigation, a procedure dubbed the closed drainage. Haematomas were collected during, and 24 hrs after, surgery. Postoperative fibrinolytic activity was lower than that observed pre-operatively. In particular, levels of tissue plasminogen activator activity (TPA), and fibrin and fibrinogen degradation products (FDP) all decreased. In contrast, coagulant activity increased postoperatively. This paper will discuss the role of local coagulofibrinolysis in the postoperative recovery of CSH patients.

Impaired fasting glucose and the risk of hypertension in Japanese men between the 1980s and the 1990s. The Osaka Health Survey

OBJECTIVE

To determine whether impaired fasting glucose (IFG) increased the risk for hypertension in two large Japanese cohorts during the different time periods.

RESEARCH DESIGN AND METHODS

We prospectively investigated two Japanese cohorts: a 1980s population, comprising 4,130 normotensive and nondiabetic men aged 35-60 years entered between 1981 and 1983, and a 1990s population, comprising 4,319 normotensive and nondiabetic men aged 35-60 years entered between 1991 and 1992. Data on lifestyle factors were obtained from questionnaires. IFG was defined as a fasting plasma glucose level > or = 110 and < 126 mg/dl.

RESULTS

During the 4-year observation period, 708 cases of hypertension were confirmed in the 1980s and 848 cases were confirmed in the 1990s. In both the 1980s and 1990s populations, IFG was associated with the risk of hypertension. The frequency of IFG in men in the 1990s group was twice as high as that in the 1980s group. The multivariate-adjusted odds ratio (OR) of hypertension was 1.54 (95% CI, 1.01-2.34) for men with IFG in the 1980s population and 1.73 (1.31-2.29) in the 1990s population, compared with those without IFG in the two populations. In the 1990s population, among lean men with a BMI < or = 23 kg/m2, men with IFG had a multivariate-adjusted OR of hypertension of 2.31 (1.46-3.65) compared with those without IFG.

CONCLUSIONS

This study demonstrated direct correlation between IFG and hypertension and greater incidence of this hypertension in the 1990s group than in the 1980s group.

Peripheral hemodynamics evaluated by acceleration plethysmography in workers exposed to lead

To clarify the effect of lead exposure on peripheral hemodynamics, acceleration plethysmography (APG) was performed for 48 male subjects occupationally exposed to lead (exposure group) and 43 male subjects with no history of occupational exposure to lead (control group). In the exposure group, the blood lead concentration (Pb-B) was also measured. Each APG parameter was assessed by comparing measured data with the standard aging curves. A significant negative correlation was obtained between the parameter--b/a and Pb-B. The exposure group showed significantly lower values of parameters--b/a (p < 0.01) and d/a (p < 0.05) than the control group. The parameter--b/a in the exposure group dose-dependently decreased with increases in length of working career (duration of exposure to lead) and Pb-B. The parameter--b/a significantly (p < 0.05) decreased in subjects with working careers of 5 years or more and in subjects whose Pb-B was 40 micrograms/100 ml or more. These results suggest that lead exposure affects peripheral hemodynamics as evaluated by APG.

Promotion of NCI-Black-Reiter male rat bladder carcinogenesis by dimethylarsinic acid an organic arsenic compound

Dimethylarsinic acid (DMAA) is a major metabolite of inorganic arsenicals in mammals. In the present study, we investigated its promoting effects on urinary bladder carcinogenesis in NCI-Black-Reiter (NBR) rats, which lack alpha2u-globulin synthesizing ability. Male 9-14-week-old NBR rats were treated sequentially with 0.05% N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) for 4 weeks and then given 100 ppm DMAA in their drinking water (group 1) for 32 weeks. Induction of preneoplastic lesions (papillary or nodular hyperplasia) in this DMAA-treated group was significantly increased as compared to the carcinogen alone control group (P < 0.01). The development of carcinomas was also enhanced and a significant increase in the 5-bromo-2'-deoxyuridine (BrdU) labeling index of the urinary bladder epithelial cells was observed for the DMAA treatment group. These results indicate that DMAA has promoting effects on urinary bladder carcinogenesis even in NBR rats, so its effects are not dependent on the presence of alpha2u-globulin.

Types of organic solvents used in workplaces and work environment conditions with special references to reproducibility of work environment classification

A survey of solvent was conducted for 196 unit work areas in 95 plants in 1994 to 1996 in Hiroshima Prefecture, Japan. The survey had been repeated every 6 months (i.e., twice a year) during the 3-year period. Sampling and analysis of the solvent vapors were carried out after national protocols set by the regulation. Toluene was most frequently detected regardless of the type of solvent work (except for degreasing), whereas the second- and the third-most common solvents varied depending on the type of solvent works. Among chlorinated hydrocarbon solvents for degreasing, dichloromethane was most widely used. Solvent concentrations were generally low as none of the median concentrations exceeded corresponding Administrative Control Levels set by the regulation, either individually or even when the assumption of additiveness was applied. Among the 1176 cases analyzed, 80% of the unit work areas were evaluated as adequate (i.e., classified as Class I). Furthermore, about 57% stayed in Class I throughout the 3 years, suggesting that solvent exposure conditions were generally quite stable. In regulatory evaluation by classification, A-sampling was decisive in most cases, whereas the role of B-sampling was limited.

Urinary excretion of arsenic metabolites after long-term oral administration of various arsenic compounds to rats

The metabolism of arsenic compounds in rats was studied by comparing urinary metabolites of arsenic compounds administered for 1 wk or 7 mo. Male F344/DuCrj rats were given 100 mg As/L as monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), trimethylarsine oxide (TMAO), or arsenobetaine (AsBe), or 10 mg As/L as arsenite [As(III)] via drinking water for 7 mo. Urine was collected by forced urination after 1 wk or 7 mo. Arsenic metabolites in urine were analyzed by ion chromatography with inductively coupled plasma mass spectrometry. In the case of As(III) ingestion, a small portion of all arsenic excreted in urine (about 6%) was excreted in inorganic form, while most arsenic was excreted as methylated arsenic metabolites. Following MMA treatments for 1 wk or 7 mo, the predominant products excreted were unchanged MMA and DMA accompanied by small amounts of TMAO and tetramethylarsonium (TeMA). In the case of DMA treatment the urinary compounds found were mainly the parent DMA and TMAO with minute amounts of TeMA. TMAO was methylated to TeMA to a slight extent after 1 wk and 7 mo of administration, although most TMAO was excreted in the form of unchanged TMAO. AsBe was predominantly eliminated in urine without any transformation. Two unidentified metabolites were detected in urine after 7 mo of arsenic species exposure; the amounts of these metabolites increased in the order DMA > MMA > TMAO with only small quantities of these detected in the As(III)-treated group. These results suggest that these unidentified metabolites are formed during a demethylation process, and not during methylation. Our findings indicate that long-term exposure to As(III), MMA, or DMA decreases the proportion of TMAO elimination in urine and increases that of DMA, M-1, and M-2, and that further methylation to TMAO to TeMA does occur to a slight extent following long-term exposure to arsenical compounds in rats.

Aneuploidy induced by dimethylarsinic acid in mouse bone marrow cells

We investigated the cytogenetic effects of dimethylarsinic acid (DMA), which is the major metabolite of inorganic arsenic compounds, on mouse bone marrow cells after a single intraperitoneal injection to mice. DMA increased mitotic indices significantly at 16, 24 and 48 h after injection, and prolonged the average generation time 1.5 h at the 24 h. These results suggest that DMA may cause mitotic arrest in vivo as well as in vitro. However the activity of mitotic arrest induced by DMA was much weaker than that induced by colchicine. Metaphase cells obtained after administration of DMA without colchicine pretreatment were morphologically normal except for chromosome number, which varied by stage from the prophase to the telophase in M phase as seen after administration of saline. DMA significantly induced aneuploids. The frequencies of euploids with DMA and saline treatment were 55.1 and 94.0%, respectively, and in DMA treatment hyperploids with 1 or 2 extra chromosomes were over 80% of all aneuploids. These results suggest that aneuploidy induced by DMA might be associated with carcinogenicity of arsenic.

The characteristics of specific IgG to phthalic anhydride (PA)-albumin conjugate

Phthalic anhydride (PA), used in the chemical industry, binds to proteins and causes allergic reactions. It is important to study the characteristics of antibody to PA-protein. We produced specific IgG against PA-rabbit serum albumin (RSA) by administering subcutaneous injections of PA-RSA conjugate to two rabbits. Both rabbits' sera had high titers of IgG not only to PA-RSA but also to PA-human serum albumin (HSA) and HSA. In enzyme-linked immunosorbent assay (ELISA) and ELISA HSA inhibition, specific IgG to PA-HSA revealed cross-reactivity to three other phthalyl anhydride conjugates, hexahydrophthalic anhydride (HHPA)-HSA, methylhexahydrophthalic anhydride (MHHPA)-HSA, and methyltetrahydrophthalic anhydride (MTHPA)-HSA, in both sera. Titers of IgG to HHPA-HSA, MHHPA-HSA, and MTHPA-HSA were not significantly different. On affinity chromatography, highly specific IgG to PA hapten alone was purified. In the serum not binding to PA column, specific IgG to PA-HSA was significantly less than in original serum, but levels of specific IgG to other phthalyl anhydride-HSA were unchanged. Rabbits immunized with PA-RSA produced at least two types of IgG: one is to PA hapten alone and the other may be against new antigenic determinants (NADs) on HSA.

Possible carcinogenic potential of dimethylarsinic acid as assessed in rat in vivo models: a review

The modifying effects of dimethylarsinic acid (DMA), the major metabolite of ingested arsenicals in most mammals, on chemical carcinogenesis were investigated using rat in vivo models and reviewed here. In a multi-organ bioassay, rats pretreated with 5 carcinogens were administered DMA at various concentrations in their drinking water. Significantly increased tumor induction due to DMA was observed in the urinary bladder, kidney, liver, and thyroid gland. This was associated with significantly elevated ornithine decarboxylase activity in the kidneys of DMA-treated animals. To estimate the hazard levels of its promoting influence, further examinations were carried out concerned with urinary bladder and liver carcinogenesis. Doses of 25 and 50 ppm, respectively, of DMA were found capable of enhancing lesion development in the two organs. In conclusion, our data indicate that DMA is a carcinogen or promoter in the urinary bladder, liver, kidney and thyroid gland, in line with previous epidemiological findings.

The urinary excretion of arsenic metabolites after a single oral administration of dimethylarsinic acid to rats

The biotransformation following oral administration of dimethylarsinic acid (DMA), an organoarsenical herbicide and the main metabolite of inorganic arsenic in mammals, was studied in rats. Male F344/DuCrj rats were administered a single dose of DMA (50 mg/kg) orally. Urine was collected at 0, 2, 4, 8, 10, 24, and 48 h after administration by forced urination. Arsenic metabolites in urine were analyzed by ion chromatography with inductively coupled plasma mass spectrometry (IC-ICP-MS). The proportions of urinary elimination of DMA, trimethylarsine oxide (TMAO), methylarsonic acid (MMA), an unidentified arsenic metabolite, and arsenite were determined at various timepoints after administration. Unmetabolized DMA was the most common form excreted during the first 4 h. Thereafter, a gradual decrease in the proportion of DMA was observed, while progressive increases in those of TMAO, the unidentified metabolite, and arsenite occurred. The proportion of TMAO excreted amounted to over 50% of all arsenic in urine between 6 and 24 h. The proportion of the unidentified metabolite and arsenite were each approximately 10% at 10 and 24 h after administration. The findings indicate that DMA administered to rats was initially excreted as unchanged DMA, and later as the methylated metabolite, TMAO. Arsenite, a demethylated metabolite of DMA, also was excreted later than elimination of DMA and TMAO. The hypothesis of demethylation by intestinal microorganisms can be supported by comparing the metabolites following oral and intraperitoneal administration. The unidentified metabolite was readily decomposed by HCl but was left unchanged by NaOH; these findings suggest that it was present in a complexed form in urine.

The inhibitory effect of selenium on induction of tetraploidy by dimethylarsinic acid in Chinese hamster cells

Arsenic is a human carcinogen. On the other hand, selenium supplementation can inhibit induction of carcinogenesis by chemical carcinogens. The effect of selenium compounds on the cytotoxicity of dimethylarsinic acid (DMA) and on the induction of tetraploidy by DMA were studied using Chinese hamster V79 cells. Two selenium compounds were tested, sodium selenite and trimethylselenonium iodide (TMSeI). Trimethylselenonium is a major excretory product of selenite metabolism. The cytotoxicity of sodium selenite was 1000-fold greater than that of TMSeI. The cytotoxicity of DMA was about the same as that of TMSeI. The mitotic index for DMA administration was increased by these selenium compounds at low concentrations and decreased by them at high concentrations. The tetraploid index for DMA decreased with increasing concentrations of these selenium compounds. Tetraploidy is a form of aneuploidy, and aneuploidy is known to induce carcinogenesis. The finding that selenium inhibited induction of tetraploidy by DMA may yield clues to the role of selenium in the chemoprevention of carcinogenesis by chemical carcinogens.