Bone morphogenetic protein-2 enhances osteoclast formation mediated by interleukin-1alpha through upregulation of osteoclast differentiation factor and cyclooxygenase-2

Bone morphogenic protein-2 (BMP-2) is a member of the transforming growth factor beta (TGF-beta) superfamily. While BMP-2 is capable of inducing bone formation ectopically, little is known about its role on osteoclastogenesis. In this study, we examined the effect of BMP-2 on osteoclast-like multinucleated cell (OCL) formation in cocultures of osteoblast-like cells and hematopoietic cells of bone marrow origin. BMP-2 alone did not stimulate OCL formation in this culture system; however, it strongly enhanced OCL formation in a dose-dependent fashion in the presence of interleukin-1alpha (IL-1alpha). Western blot analysis showed that a simultaneous addition of BMP-2 and IL-1alpha synergistically enhanced cyclooxygenase-2 (COX-2) expression in osteoblast-like cells. Moreover, Northern blot analysis revealed that the level of osteoclast differentiation factor (ODF) mRNA increased by treatment with BMP-2 and IL-1alpha in osteoblast-like cells. It is noted that BMP-2 alone did cause an increase in the expression of both COX-2 and ODF genes. The stimulatory effect of BMP-2 was abolished by adding nonsteroidal anti-inflammatory drugs, such as indomethacin and a selective COX-2 inhibitor NS-398. Addition of NS-398 inhibited the expression of the ODF gene in osteoblast-like cells treated with BMP-2 and IL-1alpha. These results indicated that the combination of BMP-2 and IL-1alpha stimulated osteoblast-like cells to elevate the expression of both COX-2 and ODF genes, resulting in an enhanced OCL formation. Since BMP-2 alone induced the expression of COX-2 and ODF genes in osteoblast-like cells, it appears to be one of the regulating factors of osteoclastogenesis.

Aerobic power as related to body growth and training in Japanese boys: a longitudinal study

Maximal aerobic power was measured for 5-6 successive years in 50 Japanese schoolboys starting from the age of 9 or 13 yr. and for 2-3 yr in 6 superior junior runners from the age of 14 yr. A large increase in aerobic power was observed during the adolescent growth spurt for 7 schoolboys who trained between the ages of 9 and 14 yr. Aerobic power for 43 average schoolboys increased from 45.0 to 52.2 ml/kg.min between the ages of 13 and 17 yr. The aerobic power of 6 superior junior runners increased from 63.4 to 73.4 ml/kg.min between the ages of 14 and 17 yr. A remarkable increase in aerobic power was not observed in trained boys before the age of peak height growth velocity (PHV). Beginning approximately 1 yr prior to the age of PHV and thereafter, training effectively increased aerobic power above the normal increase attributable to age and growth. The highly developed aerobic power found in superior junior runners may have been derived from strenuous training and partially by genetically superior endowment.

Efficacy of an acellular pertussis vaccine in Japan

To assess the efficacy of an acellular pertussis vaccine that has been used in Japan since 1981, 283 patients with pertussis were selected among patients with suspected pertussis seen at hospitals located around the Tokyo Metropolitan area from 1981 to 1983. The survey of secondary cases in household contacts showed that attack rates in children 0 to 6 years of age were 73.1% in unimmunized children, 15.0% in those fully immunized by whole-cell vaccines, and 15.4% in those given acellular vaccines. The efficacy of Japanese acellular pertussis vaccines was 79% and was not different from that of whole cell vaccines.

Comparison of blood-free medium (cyclodextrin solid medium) with Bordet-Gengou medium for clinical isolation of Bordetella pertussis

Cyclodextrin solid medium (CSM) developed by us was evaluated to be a suitable synthetic medium for the clinical isolation of Bordetella pertussis when compared with Bordet-Gengou (BG) medium. The addition of 5 micrograms of cephalexin (CEX) per ml to CSM not only supported the good growth of B. pertussis but also sufficiently suppressed the growth of nasopharyngeal flora. During period 1 of this study, nasopharyngeal specimens from 60 patients with clinical pertussis were inoculated on CSM supplemented with 5 micrograms of CEX per ml. The isolation rate was 70% (42 of 60). To confirm the efficacy of CSM, another study was performed. During period 2 of this study, nasopharyngeal specimens were cultured on both CSM and BG medium, each with 5 micrograms of CEX per ml. The comparative isolation rates were 100% (40 of 40 specimens from 29 patients) on CSM with 5 micrograms of CEX and 65% (26 out of 40) on BG medium with 5 micrograms of CEX. The excellent efficacy of CSM as measured by the isolation rate was thought to be due to the poor nutrition of this medium for the growth of nasopharyngeal bacteria. CSM retained its efficacy in clinical isolations even after 3 months of storage in a refrigerator. These data led us to conclude that CSM with 5 micrograms of CEX was much better than BG medium with 5 micrograms of CEX, determined by both the isolation rate and preservativity considerations, and that CSM with 5 micrograms of CEX per ml can be successfully used instead of BG medium as a medium for the clinical isolation of B. pertussis.

Fulminant type 1 diabetes as a high risk group for diabetic microangiopathy--a nationwide 5-year-study in Japan

AIMS/HYPOTHESIS

The aim of the present study was to assess the development of microangiopathy in patients with fulminant type 1 diabetes, a novel subtype of type 1B diabetes.

MATERIALS AND METHODS

In a nationwide survey, we followed 41 patients with fulminant type 1 diabetes and 76 age- and sex-matched patients with type 1A diabetes for 5 years. The following data were recorded every 12 months after the onset of diabetes: seven-point blood glucose concentrations, HbA1c level, urinary albumin excretion, serum C-peptide level, blood pressure, daily dosages of insulin, frequency of severe hypoglycaemic episodes, and neurological and fundoscopic examination.

RESULTS

The 5-year cumulative incidence of microangiopathy was 24.4% in fulminant type 1 diabetes and 2.6% in type 1A diabetes. In longitudinal studies using the Kaplan-Meier method, the cumulative incidence of each form of microangiopathy was significantly higher in fulminant type 1 diabetes than in type 1A diabetes; retinopathy was 9.8% vs 0% (p=0.014), nephropathy 12.2% vs 2.6% (p=0.015) and neuropathy 12.2% vs 1.3% (p=0.010), respectively. Mean HbA1c levels were similar in the fulminant and type 1A diabetes groups during the follow-up periods. However, the mean M-value, mean insulin dosages and the frequency of severe hypoglycaemic episodes were significantly higher, and the mean postprandial C-peptide level was significantly lower in the fulminant type 1 diabetes group.

CONCLUSIONS/INTERPRETATION

These data suggest that patients with fulminant type 1 diabetes are a high-risk subgroup for diabetic microangiopathy associated with the lack of endogenous insulin secretion from the onset of diabetes.

Relationship of lipoprotein lipase and hepatic triacylglycerol lipase activity to serum adiponectin levels in Japanese hyperlipidemic men

OBJECTIVE

The aim of this study was to determine how lipoprotein lipase (LPL) and hepatic triacylglycerol lipase (HTGL) activity relate to serum adiponectin levels.

RESEARCH DESIGN AND METHODS

Fifty-five hyperlipidemic Japanese men were recruited for this study. LPL and HTGL activity in post-heparin plasma (PHP) was measured using Triton X-100 emulsified-[14C] triolein. The remaining activity in the presence of 1M NaCl was defined as HTGL activity. Serum adiponectin levels were determined by an enzyme-linked immunosorbent assay system.

RESULT

LPL activity had a positive relationship with HDL2, but had no relation with HDL3, while HTGL had positive relationship with HDL3, but had no relationship with HDL2. LPL activity showed a positive relationship [r = 0.345, p = 0.010] to serum adiponectin levels, while and HTGL activity showed an inverse relationship [r = - 0.365 p = 0.006]. Multiple regression analysis with LPL and HTGL as dependent variables and age, BMI, serum adiponectin and the homeostasis model assessment of insulin resistance (HOMA-IR) as independent variables showed LPL and HTGL's association to adiponectin did not persist after adjustments for these covariants. However, the association of LPL activity to HOMA-IR was found to persist after adjustments of age, BMI, and serum adiponectin.

CONCLUSIONS

There was a co-linearity between insulin sensitivity and adiponectin as well as insulin sensitivity and LPL/HTGL activity.

Adverse reactions and antibody responses to acellular pertussis vaccine

Two types of acellular pertussis vaccine are used in Japan: the filamentous hemagglutinin (F-HA) predominant type and the pertussis toxin (PT)-F-HA type. We tested one lot of vaccine from each of three manufacturers (lots A and B, F-HA predominant type; lot C, PT-F-HA type). One hundred fifteen healthy children between the ages of 3 months and 23 months were immunized with one of the three lots of acellular pertussis vaccine to assess adverse reactions and antibody responses. The incidence of fever (temperature greater than or equal to 38 degrees C) was 2.6% for lot A, 1.2% for lot B, and 2.5% for lot C. The incidence of local reactions greater than 5 cm in diameter was 1.9% for lot A, 2.4% for lot B, and 3.3% for lot C. Thus no significant differences in adverse reaction were observed. The anti-PT antibody responses in the tested vaccines were equal to or greater than those in patients with pertussis in the convalescent stage, and the anti-F-HA antibody responses were far higher than those of convalescing patients. Lot C produced the highest anti-PT antibody, and Lot A the highest anti-F-HA antibody.

Possible involvement of protein kinases and Smad2 signaling pathways on osteoclast differentiation enhanced by activin A

Bone tissues reportedly contain considerable amounts of activin A and follistatin, an activin A-binding protein. In the present study, we found that follistatin strongly inhibited osteoclast formation in cocultures of mouse bone marrow cells and primary osteoblasts induced by 1alpha,25 dihydroxyvitamin D(3), prostaglandin E(2), and interleukin-1alpha. Antibody aganist activin A also inhibited the osteoclast formation. Furthermore, activin A synergistically stimulated osteoclast differentiation mediated by receptor activator NF-kappaB ligand (RANKL). RT-PCR analysis revealed that osteoblasts produced not only activin A but also follistatin. Western blot analysis of a panel of phosphorylated proteins revealed that activin A stimulated the phosphorylation of p44/42 mitogen activated protein (MAP) kinase (ERK1/2) and p38 MAP kinase in macrophage colony-stimulating factor-dependent bone marrow macrophages (M-BMMPhis). In addition, phosphorylation of Smad2 was observed in M-BMMPhis stimulated with activin A. These findings indicate that the phosphorylation of p44/42 MAP kinase, p38 MAP kinase, and Smad2 is involved in activin A-enhanced osteoclast differentiation induced by RANKL. Taken together, these results suggest that both activin A and follistatin produced by osteoblasts may play an important role in osteoclast differentiation through MAP kinases and Smad2 signaling pathways.

In Vitro Evolution of Unmodified 16S rRNA for Simple Ribosome Reconstitution

One of the largest challenges in the synthesis of artificial cells that can reproduce is in vitro assembly of ribosomes from in vitro synthesized rRNAs and proteins. In this study, to circumvent the post-transcriptional modification of 16S rRNA for reconstitution of the fully active 30S subunit, we performed artificial evolution of 16S rRNA, which forms the functional 30S subunit without post-transcriptional modifications. We first established an in vitro selection scheme by combining the integrated synthesis, assembly, and translation (iSAT) system with the liposome sorting technique. After 15 rounds of selection cycles, we found one point mutation (U1495C) near the 3' terminus that significantly enhanced the reconstitution activity of the functional 30S subunit from unmodified 16S rRNA to approximately 57% of that from native-modified 16S rRNA. The effect of the mutation did not depend on the reconstitution scheme, anti-SD sequences, or the target genes to be translated. The mutation we found in this study enabled reconstitution of the active 30S subunit without rRNA modification, and thus would be a useful tool for simple construction of self-reproducing ribosomes.

In Vitro Biocompatibility of a New Titanium-29Niobium-13Tantalum-4.6Zirconium Alloy With Osteoblast-Like MG63 Cells

BACKGROUND

Titanium-29niobium-13tantalum-4.6zirconium (TiNb) has recently been developed as a new implant material. TiNb is composed of non-toxic elements and has a lower modulus of elasticity than the other titanium alloys. However, its biocompatibility has not been adequately characterized. The aim of this study was to evaluate the biocompatibility of TiNb using an osteoblast-titanium co-culture system.

METHODS

MG63 cells were cultured on three kinds of titanium disks: TiNb, pure titanium (pTi), and titanium-6aluminum-4vanadium (TiAl), prepared with two different surfaces, a polished and acid-etched surface and a machined-grooved surface. The surface topography and roughness were evaluated by scanning electron microscopy (SEM). After 48 hours culture, the number of proliferating cells and prostaglandin E2 (PGE2) production in the culture supernatant were determined.

RESULTS

There was no significant difference in surface roughness among the three titanium disks with a polished and acid-etched surface. After 48 hours of culture, the number of cells was significantly reduced on pTi and TiAl compared to TiNb and the control. PGE2 production was significantly higher on pTi than on TiAl, TiNb, and the control. We further examined the effect of surface roughness on PGE2 production using machine-grooved titanium disks. While pTi and TiAl stimulated the production of PGE2 depending on surface roughness, roughened TiNb did not affect PGE2 production.

CONCLUSIONS

These results suggest that TiNb may exhibit favorable biocompatibility because it has an efficient surface topography for cell proliferation, and the level of PGE2 production does not depend on surface roughness. We conclude that TiNb may be useful as an implant material.

International expert consensus on precision anatomy for minimally invasive pancreatoduodenectomy: PAM-HBP surgery project

BACKGROUND

The anatomical structure around the pancreatic head is very complex and it is important to understand its precise anatomy and corresponding anatomical approach to safely perform minimally invasive pancreatoduodenectomy (MIPD). This consensus statement aimed to develop recommendations for elucidating the anatomy and surgical approaches to MIPD.

METHODS

Studies identified via a comprehensive literature search were classified using the Scottish Intercollegiate Guidelines Network method. Delphi voting was conducted after experts had drafted recommendations, with a goal of obtaining >75% consensus. Experts discussed the revised recommendations with the validation committee and an international audience of 384 attendees. Finalized recommendations were made after a second round of online Delphi voting.

RESULTS

Three clinical questions were addressed, providing six recommendations. All recommendations reached at least a consensus of 75%. Preoperatively evaluating the presence of anatomical variations and superior mesenteric artery (SMA) and superior mesenteric vein (SMV) branching patterns was recommended. Moreover, it was recommended to fully understand the anatomical approach to SMA and intraoperatively confirm the SMA course based on each anatomical landmark before initiating dissection.

CONCLUSIONS

MIPD experts suggest that surgical trainees perform resection based on precise anatomical landmarks for safe and reliable MIPD.

Cord blood IgE against milk and egg antigens

The aim of the present study was to reevaluate the prenatal production of specific IgE for eggs and milk and, in those cases, to determine whether there is a relation to the amount of maternal egg and milk intake. Total and specific IgEs from 160 cord blood-samples were determined by immunoassays using a paramagnetic particle solid phase and an enzyme-mediated chemiluminescent reaction for signal detection. The levels of cord blood IgE for total, egg, and milk were 0.63 +/- (SD) 1.10 IU/ml, 0.020 +/- 0.055, and 0.036 +/- 0.053 IU/ml, respectively. IgE levels specific to egg and milk over 0.03 IU/ml were observed in 33 and 70 out of 160 cases, respectively. To address whether the maternal intake of eggs and milk affects the level of cord blood IgEs, all mothers except 9 were interviewed, and the amount of eggs and milk taken during pregnancy was recorded. No correlation was seen between egg and milk intakes and cord blood IgE levels. Our data demonstrate a high incidence of the prenatal production of specific IgE for eggs and milk which is independent of maternal egg and milk intakes.

Surgical approaches for minimally invasive distal pancreatectomy: A systematic review

BACKGROUND

Minimally invasive distal pancreatectomy (MIDP) was initially performed for benign tumors, but recently its indications have steadily broadened to encompass other conditions including pancreatic malignancies. Thorough anatomical knowledge is mandatory for precise surgery in the era of minimally invasive surgery. However, expert consensus regarding anatomical landmarks to facilitate the safe performance of MIDP is still lacking.

METHODS

A systematic literature search was performed using keywords to identify articles regarding the vascular anatomy and surgical approaches/techniques for MIDP.

RESULTS

All of the systematic reviews revealed that MIDP was not associated with an increase in postoperative complications. Moreover, most showed that MIDP resulted in less blood loss than open surgery. Regarding surgical approaches for MIDP, a standardized stepwise procedure improved surgical outcomes, including blood loss, operative time, and major complications. There are two approaches to the splenic vessels, superior and inferior; however, no study has ever directly compared them with respect to clinical outcomes. The morphology of the splenic artery affects the difficulty of approaching the artery's root. To select an appropriate dissecting layer when performing posterior resection, thorough knowledge of the anatomy of the fascia, left renal vein/artery, and left adrenal gland is needed.

CONCLUSIONS

In MIDP, a standardized approach and precise knowledge of anatomy facilitates safe surgery and has the advantage of a shorter learning curve. Anatomical features and landmarks are particularly important in cases of radical MIDP and splenic vessel preserving MIDP.

Pertussis in adults

A survey was conducted of 89 households in each of which at least one patient with culture-confirmed pertussis had been detected. The source of infection was found to be an adult in 10 (11.2%) of the 89 households, and the rate of secondary attack was 19 (10.3%) of 185. Furthermore, a laboratory study disclosed 17 adults with subclinical pertussis; the subclinical infection rate was 17 (25.0%) of 68. When compared with pertussis in young children, the adult illness was generally less severe and had different clinical features. Adult pertussis showed neither leukocytosis nor lymphocytosis, but it produced anti-pertussis toxin antibody more quickly and higher levels of anti-filamentous hemagglutinin and agglutinin antibodies, and showed stronger growth inhibition of Bordetella pertussis. Although adult pertussis is usually unrecognized because of its different clinical and laboratory features, it is a significant health threat that requires some measures for disease control.

Two novel Salp15-like immunosuppressant genes from salivary glands of Ixodes persulcatus Schulze tick

Salp15, a 15-kDa tick salivary gland protein, is known for several suppressive activities against host immunity and critical functions for the transmission of Lyme borrelia in Ixodes scapularis and Ixodes ricinus, the major vectors found in North America and Western Europe. Salp15 inhibits the activation of cluster of differentiation (CD)4(+)T-cells through the repression of T-cell receptor (TCR)-triggered calcium fluxes and interleukin (IL)-2 production. Furthermore, Salp15 adheres to the spirochaeta and specifically interacts with its outer surface protein C. The binding of Salp15 to Borrelia burgdorferi protects it from antibody-mediated killing in vitro. The aim of this study is to identify the Salp15 genes in Ixodes persulcatus Schulze, the specific vector for human Lyme borreliosis in Japan. Two cDNA clones encoding the Salp15-like sequence were obtained from salivary glands of fed female ticks. These genes encode 135- and 132-amino acid proteins, designated Salp15 Iper-1 and Salp15 Iper-2, respectively, both having signal peptide sequences and predicted to be secretory proteins. Salp15 Iper-1 and -2 showed 51.8 and 68.2% similarity to I. scapularis Salp15, respectively. Reverse transcriptase PCR analysis showed that Salp15 Iper genes were expressed specifically in the salivary glands throughout life cycle stages of the ticks and were up-regulated by blood feeding. In the I. persulcatus-derived sequences, the C-terminal part, which is the binding domain to the CD4 molecule of T-cells in I. scapularis Salp15, was well conserved. In the future, it will be necessary to analyse immunosuppressive functions of I. persulcatus Salp15 and their interaction with Borrelia spp. in Japan.

Comparison of urine cytology between the ileal conduit and Indiana pouch

OBJECTIVE

To compare the cytomorphologic features of urine obtained from two different kinds of urinary diversions constructed after total bladder resection.

STUDY DESIGN

The smears of urine from 11 ileal conduits and 6 Indiana pouches were evaluated. All patients underwent total bladder resection due to transitional cell carcinoma (TCC) or other kinds of cancer before urine diversion.

RESULTS

The cytologic features of Indiana pouch urine include degenerated, small, round cells without columnar cells derived from intestinal epithelium. In ileal conduit urine, well-preserved columnar cells and degenerated, small, round cells were frequently observed. The columnar cells in ileal conduit urine exhibited cytologic features that should be distinguished from TCC cells.

CONCLUSION

The method of reconstructing the urinary tract is important in urine cytology from urine diversions because the cytomorphologic features of urine are different between the two kinds of urinary diversions. Since columnar cells in ileal conduit urine might lead to misdiagnosis as TCC, special consideration is required to examine ileal conduit urine.

[Effect of posture strategies on preventing aspiration]

The purpose of this study was to determine the effect of postural change on preventing aspiration, and the types of swallowing disorder that were influenced by posture. Ninety-five patients that were examined by aspiration of barium during videofluoroscopic examination of oropharyngeal swallow assumed one of four postures (chin down, head rotation, chin down + head rotation, and head back to chin down). Postural strategies were successful in eliminating aspiration in 68(72%) of the 95 patients. Twenty five of the 68 patients, however, needed an additional change in bolus volume to eliminate aspiration. Effective postures eliminating aspiration were chin down for 43 patients, head rotation for 10 patients, chin down + head rotation for 12 patients, and head back to chin down for 3 patients. The successes rates of posture changes for each swallowing abnormality were 76% for reduced tongue base retraction, 74% for delay in triggering pharyngeal swallow, 74% for reduced laryngeal elevation, 73% for laryngeal paralysis, 68% for inefficient oral transit, and in 57% for cricopharyngeal dysfunction. Among individuals with cricopharyngeal dysfunction or with than three swallowing motility problems, the frequency of unsuccessful swallow despite postural change was significantly higher than that of successful swallow. These results indicated that the posture strategies in addition to control of bolus volume could prevent aspiration in more than 70% of patients, but the efficacy of posture techniques differed with the different types of swallowing disorder identified as causing the aspiration, and suggested that the posture strategies were less beneficial in individuals with cricopharyngeal dysfunction or exhibiting multiple swallowing disorders.

A causal relationship between Bordetella pertussis and Bordetella parapertussis infections

Bordetella parapertussis is isolated during the late stages of pertussis outbreaks and occasionally from patients infected with pertussis. The relationship between Bordetella pertussis and B. parapertussis was investigated in mice with monoinfections and mixed infections. Four groups of 10 2-week-old suckling mice were studied: mice born to mice vaccinated against pertussis during pregnancy and unvaccinated controls consequently did and did not receive antipertussis toxin (PT) antibody transcolostrally. The mice were infected transnasally with B. parapertussis strain 422 and 2 identical groups were infected transnasally with B. parapertussis strain 422 and B. pertussis strain 18-323. Bacterial colonization of the lungs and trachea was studied at 1, 2, and 3 weeks after challenge. No persistent colonization by B. parapertussis of the lungs or trachea of monoinfected suckling mice were observed. Persistent colonization by B. parapertussis was observed when suckling mice that received anti-PT antibody transcolostrally were infected with both species. These findings are consistent with the clinical characteristics of B. parapertussis. The results of this study demonstrate that B. pertussis infection facilitates B. parapertussis infection.

Surgery after sunitinib administration to improve survival of patients with advanced pancreatic neuroendocrine neoplasms

BACKGROUND

Little research is available regarding the treatments combining surgical resection with systemic chemotherapy for advanced pancreatic neuroendocrine neoplasm patients. We retrospectively elucidated whether sunitinib administration before surgery in advanced pancreatic neuroendocrine neoplasm (Pan-NEN) patients increases survival.

METHODS

This study included 106 of 326 Pan-NEN patients with distant metastases and/or unresectable locally advanced tumors who visited our department to receive sunitinib for more than 1 mo during April 2002 to December 2019. Risk factors for overall survival (OS) and disease-free survival (DFS) were analyzed.

RESULTS

The median duration of preoperative sunitinib administration and observation time after sunitinib were 6 and 26.5 mo, respectively. Of 106 patients, 31 (29.2%) underwent surgery following sunitinib administration. Hepatectomy, synchronous hepatopancreatectomy, pancreatectomy, and lymphadenectomy were performed for 13, 12, 5, and 1 patient, respectively. The 5-y OS rates in the resected and nonresected groups were 88.9% and 14.1%, respectively (P < .001). In the multivariate analysis, the absence of surgical resection following sunitinib (hazard ratio [HR], 13.1; P = .001), poor differentiation (HR, 5.5; P = .007), and bilateral liver metastases (HR, 3.7; P = .048) were independent risk factors for OS, although large liver tumor volumes were more evident in the nonresected group, as patient characteristics. The median DFS was 16.1 mo in 22 patients who underwent R0/1 resections, and risk factors for postoperative recurrence were Ki-67 index >7.8% (HR, 7.4; P = .02) and R1 resection (HR, 4.4; P = .04).

CONCLUSION

Surgical resection after sunitinib administration improved OS in advanced Pan-NENs.

Assay of 222Rn in water samples by a modified integral counting method

22Rn activity concentrations in water collected from 163 private wells and 14 springs in Tokyo were measured with a liquid scintillation spectrometer using a modified integral counting method. The activity concentrations of 222Rn range from 0.2 to 22.9 Bq/L and average 4.8 Bq/L. The errors due to the air luminescence counts and the interferences from 220Rn and 219Rn are discussed and evaluated. 222Rn samples of 0.2 Bq/L can be assayed within an overall uncertainty of 3.1%. The liquid scintillation method involving agitation of the sample water directly with a liquid scintillation cocktail was compared with the present method and evaluated.