Distinct phosphorylation states of mammalian CaMKIIβ control the induction and maintenance of sleep

The reduced sleep duration previously observed in Camk2b knockout mice revealed a role for Ca2+/calmodulin-dependent protein kinase II (CaMKII)β as a sleep-promoting kinase. However, the underlying mechanism by which CaMKIIβ supports sleep regulation is largely unknown. Here, we demonstrate that activation or inhibition of CaMKIIβ can increase or decrease sleep duration in mice by almost 2-fold, supporting the role of CaMKIIβ as a core sleep regulator in mammals. Importantly, we show that this sleep regulation depends on the kinase activity of CaMKIIβ. A CaMKIIβ mutant mimicking the constitutive-active (auto)phosphorylation state promotes the transition from awake state to sleep state, while mutants mimicking subsequent multisite (auto)phosphorylation states suppress the transition from sleep state to awake state. These results suggest that the phosphorylation states of CaMKIIβ differently control sleep induction and maintenance processes, leading us to propose a "phosphorylation hypothesis of sleep" for the molecular control of sleep in mammals.

Generation of gene-corrected iPSCs line (KEIUi001-A) from a PARK8 patient iPSCs with familial Parkinson's disease carrying the I2020T mutation in LRRK2

Leucine-rich repeat kinase 2 (LRRK2) is the causal gene of the autosomal dominant hereditary form of Parkinson's disease (PD), PARK8. We have previously reported that induced pluripotent stem cells (iPSCs) from a PARK8 patient with I2020T LRRK2 mutation replicated to some extent the pathologic phenotype evident in the brain of PD patients. In the present study, we generated gene-corrected iPSCs line, KEIUi001-A, using TALEN-mediated genome editing. KEIUi001-A retained a normal karyotype and pluripotency, i.e. the capacity to differentiate into cell types of the three germ layers. This iPSCs will be valuable for clarifying various aspects of LRRK2-related pathology.

Rapid and easy-to-use ES cell manipulation device with a small groove near culturing wells

Objective

Production of genetically modified mice including Knock-out (KO) or Knock-in (KI) mice is necessary for organism-level phenotype analysis. Embryonic stem cell (ESC)-based technologies can produce many genetically modified mice with less time without crossing. However, a complicated manual operation is required to increase the number of ESC colonies. Here, the objective of this study was to design and demonstrate a new device to easily find colonies and carry them to microwells.

Results

We developed a polydimethylsiloxane-based device for easy manipulation and isolation of ESC colonies. By introducing ESC colonies into the groove placed near culturing microwells, users can easily find, pick up and carry ESC colonies to microwells. By hydrophilic treatment using bovine serum albumin, 2-μL droplets including colonies reached the microwell bottom. Operation time using this device was shortened for both beginners (2.3-fold) and experts (1.5-fold) compared to the conventional colony picking operation. Isolated ESC colonies were confirmed to have maintained pluripotency. This device is expected to promote research by shortening the isolation procedure for ESC colonies or other large cells (e.g. eggs or embryos) and shortening training time for beginners as a simple sorter.

Muscarinic Acetylcholine Receptors Chrm1 and Chrm3 Are Essential for REM Sleep

Sleep regulation involves interdependent signaling among specialized neurons in distributed brain regions. Although acetylcholine promotes wakefulness and rapid eye movement (REM) sleep, it is unclear whether the cholinergic pathway is essential (i.e., absolutely required) for REM sleep because of redundancy from neural circuits to molecules. First, we demonstrate that synaptic inhibition of TrkA+ cholinergic neurons causes a severe short-sleep phenotype and that sleep reduction is mostly attributable to a shortened sleep duration in the dark phase. Subsequent comprehensive knockout of acetylcholine receptor genes by the triple-target CRISPR method reveals that a similar short-sleep phenotype appears in the knockout of two Gq-type acetylcholine receptors Chrm1 and Chrm3. Strikingly, Chrm1 and Chrm3 double knockout chronically diminishes REM sleep to an almost undetectable level. These results suggest that muscarinic acetylcholine receptors, Chrm1 and Chrm3, are essential for REM sleep.

Next-generation human genetics for organism-level systems biology

Systems-biological approaches, such as comprehensive identification and analysis of system components and networks, are necessary to understand design principles of human physiology and pathology. Although reverse genetics using mouse models have been used previously, it is a low throughput method because of the need for repetitive crossing to produce mice having all cells of the body with knock-out or knock-in mutations. Moreover, there are often issues from the interspecific gap between humans and mice. To overcome these problems, high-throughput methods for producing knock-out or knock-in mice are necessary. In this review, we describe 'next-generation' human genetics, which can be defined as high-throughput mammalian genetics without crossing to knock out human-mouse ortholog genes or to knock in genetically humanized mutations.

Easy and efficient production of completely embryonic-stem-cell-derived mice using a micro-aggregation device

There is an increasing demand for genetically modified mice produced without crossing, for rapid phenotypic screening studies at the organismal level. For this purpose, generation of completely embryonic-stem-cell (ESC)-derived chimeric mice without crossing is now possible using a microinjection or aggregation method with 3i culture medium. However, the microinjection of ESCs into blastocyst, morula, or 8-cell-stage embryos requires a highly skilled operator. The aggregation method is an easier alternative, but the conventional aggregation protocol still requires special skills. To make the aggregation method easier and more precise, here we developed a micro-aggregation device. Unlike conventional 3-dimensional culture, which uses hanging-drop devices for aggregation, we fabricated a polystyrene funnel-like structure to smoothly drop ESCs into a small area (300-μm in diameter) at the bottom of the device. The bottom area was designed so that the surface tension of the liquid-air interface prevents the cells from falling. After aggregation, the cells can be recovered by simply exerting pressure on the liquid from the top. The microdevice can be set upon a regular 96-well plate, so it is compatible with multichannel pipette use or machine operation. Using the microdevice, we successfully obtained chimeric blastocysts, which when transplanted resulted in completely ESC-derived chimeric mice with high efficiency. By changing the number of ESCs in the aggregate, we found that the optimum number of co-cultured ESCs was around 90~120 per embryo. Under this condition, the efficiency of generating completely ESC-derived mice was the same or better than that of the injection method. These results indicated that our microdevice can be used to produce completely ESC-derived chimeric mice easily and with a high success rate, and thus represents a promising alternative to the conventional microinjection or aggregation method, especially for high-throughput, parallel experimental applications.

Next-generation mammalian genetics toward organism-level systems biology

Organism-level systems biology in mammals aims to identify, analyze, control, and design molecular and cellular networks executing various biological functions in mammals. In particular, system-level identification and analysis of molecular and cellular networks can be accelerated by next-generation mammalian genetics. Mammalian genetics without crossing, where all production and phenotyping studies of genome-edited animals are completed within a single generation drastically reduce the time, space, and effort of conducting the systems research. Next-generation mammalian genetics is based on recent technological advancements in genome editing and developmental engineering. The process begins with introduction of double-strand breaks into genomic DNA by using site-specific endonucleases, which results in highly efficient genome editing in mammalian zygotes or embryonic stem cells. By using nuclease-mediated genome editing in zygotes, or ~100% embryonic stem cell-derived mouse technology, whole-body knock-out and knock-in mice can be produced within a single generation. These emerging technologies allow us to produce multiple knock-out or knock-in strains in high-throughput manner. In this review, we discuss the basic concepts and related technologies as well as current challenges and future opportunities for next-generation mammalian genetics in organism-level systems biology.

Systems biology of mammalian circadian clocks

Systems biology is a natural extension of molecular biology; it can be defined as biology after identification of key gene(s). Systems-biological research is a multistage process beginning with (a) the comprehensive identification and (b) quantitative analysis of individual system components and their networked interactions, which lead to the ability to (c) control existing systems toward the desired state and (d) design new ones based on an understanding of the underlying structure and dynamical principles. In this review, we use the mammalian circadian clock as a model system and describe the application of systems-biological approaches to fundamental problems in this model. This application has allowed the identification of transcriptional/posttranscriptional circuits, the discovery of a temperature-insensitive period-determining process, and the discovery of desynchronization of individual clock cells underlying the singularity behavior of mammalian clocks.

Melanopsin-dependent photo-perturbation reveals desynchronization underlying the singularity of mammalian circadian clocks

Singularity behaviour in circadian clocks--the loss of robust circadian rhythms following exposure to a stimulus such as a pulse of bright light--is one of the fundamental but mysterious properties of clocks. To quantitatively perturb and accurately measure the dynamics of cellular clocks, we synthetically produced photo-responsiveness within mammalian cells by exogenously introducing the photoreceptor melanopsin and continuously monitoring the effect of photo-perturbation on the state of cellular clocks. Here we report that a critical light pulse drives cellular clocks into singularity behaviour. Our theoretical analysis consistently predicts and subsequent single-cell level observation directly proves that desynchronization of individual cellular clocks underlies singularity behaviour. Our theoretical framework also explains why singularity behaviours have been experimentally observed in various organisms, and it suggests that desynchronization is a plausible mechanism for the observable singularity of circadian clocks. Importantly, these in vitro and in silico findings are further supported by in vivo observations that desynchronization underlies the multicell-level amplitude decrease in the rat suprachiasmatic nucleus induced by critical light pulses.

Isolation and Characterization of a Novel Human Radiosusceptibility Gene, NP95

The murine nuclear protein Np95 has been shown to underlie resistance to ionizing radiation and other DNA insults or replication arrests in embryonic stem (ES) cells. Using the databases for expressed sequenced tags and a two-step PCR procedure, we isolated human NP95, the full-length human homologue of the murine Np95 cDNA, which consists of 4,327 bp with a single open reading frame (ORF) encoding a polypeptide of 793 amino acids and 73.3% homology to Np95. The ORF of human NP95 cDNA is identical to the UHRF1 (ubiquitin-like protein containing PHD and RING domain 1). The NP95 gene, assigned to 19p13.3, consists of 18 exons, spanning 60 kb. Several stable transformants from HEK293 and WI-38 cells that had been transfected with the antisense NP95 cDNA were, like the murine Np95-knockout ES cells, more sensitive to X rays, UV light and hydroxyurea than the corresponding parental cells. In HEK293 cells, the lack of NP95 did not affect the activities of topoisomerase IIalpha, whose expression had been demonstrated to be regulated by the inverted CCAAT box binding protein of 90 kDa (ICBP90) that closely resembles NP95 in amino acid sequence and in cDNA but differs greatly in genomic organization. These findings collectively indicate that the human NP95 gene is the functional orthologue of the murine Np95 gene.

No meaningful increase in urinary tubular dysfunction markers in a population with 3 microg cadmium/g creatinine in urine

The critical Cd exposure level to induce tubular dysfunctions is a focus of public concern among general populations in Japan. To answer this question, one group each (about 1000 adult women/area) in nonpolluted areas with high (Area H) and low Cd exposure (Area L) was obtained, and 742 strictly age-matched pairs of never-smoking adult women were selected for comparison. Cd, alpha1-MG (microglobulin) and beta2- MG in urine were taken as markers of exposure and tubular dysfunction, respectively. Geometric mean Cd levels as corrected for creatinine (Cdcr) was greater than three times higher in Area H (2.8 microg/g cr) than in Area L (0.8 microg/g cr). Nevertheless, beta2-MGcr did not differ between the two areas (125 microg/g cr for Area H vs 118 microg/g cr for Area L). alpha1-MGcr was only marginally higher in Area H (2.8 mg/g cr) than in Area L (2.1 mg/g cr), with no biomedical significance. Results were essentially the same when analyses were conducted with noncorrected observed values or values corrected for a specific gravity. Thus, the effects of Cd exposure in Area H on renal tubular function should be essentially nil.

Pharmacological characterization of 5-hydroxytryptamine-induced contraction in the chicken gastrointestinal tract

5-Hydroxytryptamine (5-HT) receptor subtypes involved in 5-HT-induced contraction of the chicken gastrointestinal tract were characterized pharmacologically using subtype-selective agonists and antagonists. The proventriculus (area of stomach adjacent to the oesophagus) and ileum are examined. 5-HT applied cumulatively caused sustained contraction of the proventriculus that was not decreased by tetrodotoxin, atropine or l-nitro-arginine methylester (l-NAME). alpha-Methyl-5-HT showed the same potency as that of 5-HT, indicating the involvement of the 5-HT(2) receptor. (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-amino-propane (DOI), 5-methoxytryptamine and 1-(3-chlorophenyl)piperazine hydrochloride (mCPP) were potent, and 2-methyl-5-HT, 5-carboxamidotryptamine, BW723C86 and 6-chloro-2-(1-piperazinyl)pyrazine hydrochloride (MK212) were moderate, but (+/-)-8-hydroxy-2-dipropylaminotetralin hydrobromide (8-OH-DPAT), [endo-N-8-methyl-8-azabicyclo-(3,2,1)oct-3-yl]-2,3-dihydro-(1-methyl)ethyl-2-oxo-1H-benzimidazol-1-carboxamide (BIMU-8) and cisapride were weak agonists. Correlation of pEC(50) values of these agonists with documented pEC(50) values for 5-HT(2C) receptor was higher than 5-HT(2A) and 5-HT(2B). Cinanserin, ketanserin, methiothepin, methysergide, mianserin, (8-[5-(2,4-dimethoxy-5-(4-trifluoromethylphenylsulphonamido)phenyl-5-oxopentyl)-1,3,8-triazaspiro[4,5]decane-2,4-dione hydrochloride (RS102221), N-(1-methyl-1H-indolyl-5-yl)-N'-(3-methyl-5-isothiazolyl)urea (SB204741), spiperone and N-desmethylclozapine concentration-dependently inhibited the contractile responses to 5-HT. Correlation of pK(b)/pA(2) of antagonists with documented pK(i) for 5-HT(2C) receptor was highest among 5-HT(2) receptor subtypes. In the methysergide- and ketanserin-treated proventriculus, 5-HT, 2-methyl-5-HT and cisapride did not enhance the electrical field stimulation (5 Hz)-induced cholinergic contractions. 5-HT applied non-cumulatively caused transient contraction of ileum, and the responses were partly decreased by atropine or tetrodotoxin. 5-Methoxytryptamine, alpha-methyl-5-HT, 5-carboxamidotryptamine, L692,247 and DOI were potent agonists. However, 2-methyl-5-HT, cisapride, BW723C86, 8-OH-DPAT and 5-nonyloxytryptamine, mCPP and MK212 were less effective. Ketanserin and methysergide decreased the 5-HT-induced ileal contraction, but neither GR113808 nor SB269970 inhibited the responses. In conclusion, 5-HT causes contraction of the proventriculus via 5-HT(2C)-like receptors present on smooth muscle. 5-HT also causes contraction of the ileum, but the underlying mechanisms are complex, involving neural and smooth muscle components, and both 5-HT(1)- and 5-HT(2)-like receptors. Neural 5-HT receptors similar to 5-HT(3)/5-HT(4) receptors were not found in the chicken proventriculus and ileum.

Low-level cadmium exposure in Toyama City and its surroundings in Toyama prefecture, Japan, with references to possible contribution of shellfish intake to increase urinary cadmium levels

OBJECTIVES

This study was initiated to examine if exposure to cadmium (Cd) was high also outside of the previously identified Itai-itai disease endemic region in the Jinzu River basin in Toyama prefecture in Japan.

METHODS

Morning spot urine samples were collected in June-August 2004 from 651 adult women (including 535 never-smokers) in various regions in Toyama prefecture, and subjected to urinalyses for cadmium (Cd), alpha1-microglobulin (alpha1-MG), beta2-microglobulin (beta2-MG), N-acetyl-beta-D-glucosaminidase (NAG), specific gravity (SG or sg) and creatinine (CR or cr). Three months later, the second urine samples were collected from those with elevated Cd in urine (e.g., > or =4 microg/g cr), together with answers to questionnaires on shellfish consumption.

RESULTS

The geometric mean (GM) Cd, alpha1-MG, beta2-MG and NAG (after correction for CR) for the total participants were 2.0 microg/g cr, 2.4 mg/g cr, 104 microg/g cr and 2.8 units/g cr, respectively; further analysis with never-smoking cases only did not induce significant changes in these parameters. Analyses of the second urine samples from the high Cd subjects showed that there was substantial decrease (to about a half) in Cd in the 3-month period, and that the decrease was accompanied by reduction in alpha1-MG and NAG (beta2-MG did not show elevation even in the first samples). The urinalysis results in combination with the results of the questionnaire survey suggest that the high urinary Cd was temporary and might be induced by intake of shellfish that is edible whole.

CONCLUSIONS

The overall findings appear to suggest that Cd exposure in Toyama populations (outside of the Itai-itai disease endemic region) was at the levels commonly observed on the coast of the Sea of Japan, and that the Cd level in urine might be modified by the intake of some types of seafood. Further studies are necessary to elucidate the relation of urinary Cd with seafood intake.

Feedback repression is required for mammalian circadian clock function

Direct evidence for the requirement of transcriptional feedback repression in circadian clock function has been elusive. Here, we developed a molecular genetic screen in mammalian cells to identify mutants of the circadian transcriptional activators CLOCK and BMAL1, which were uncoupled from CRYPTOCHROME (CRY)-mediated transcriptional repression. Notably, mutations in the PER-ARNT-SIM domain of CLOCK and the C terminus of BMAL1 resulted in synergistic insensitivity through reduced physical interactions with CRY. Coexpression of these mutant proteins in cultured fibroblasts caused arrhythmic phenotypes in population and single-cell assays. These data demonstrate that CRY-mediated repression of the CLOCK/BMAL1 complex activity is required for maintenance of circadian rhythmicity and provide formal proof that transcriptional feedback is required for mammalian clock function.

Smoking-induced increase in urinary cadmium levels among Japanese women

OBJECTIVE

To examine if cigarette smoking will induce elevation in cadmium (Cd) in urine.

METHODS

Information on smoking habits, and urinary levels of cadmium (Cd-U), alpha(1)-microglobulin (alpha(1)-MG), beta(2)-microglobulin (beta(2)-MG), creatinine (CR or cr), and urine specific gravity (SG or sg) was cited from a combination of three previously established databases on adult Japanese women. After exclusion of those with unclear answers on smoking habits (412 cases), the combination (12,846 cases) gave 11,092, 1420 and 334 cases of never, current and former smokers, respectively, for present statistical analyses.

RESULTS

Multiple regression analyses taking Cd-U as a dependent variable and 11 regions of urine collection, age and smoking habits as independent variables showed that age and regions were powerful confounders in the analysis for the effects of smoking on Cd-U. To exclude the confounding effects, current and former smokers were paired with age- and region-matched never smoking controls in subsequent analyses. In addition, former smokers were paired with age- and region-matched current smokers. The comparison of the paired cases showed that Cd-U for current smokers was significantly higher than that for never smokers. The levels for former smokers were however not higher than the levels for never smokers. When classified by the number of cigarettes consumed per day, Cd-U for current smokers increased dependently to the number of cigarettes (about 0.09 microg/cigarette/day) with leveling off at 15 or more cigarettes. There was a subtle cigarette dose-dependent increase in alpha(1)-MG, but the increase was insignificant in case of beta(2)-MG. Estimation of the amount of Cd absorbed due to cigarette smoking followed by comparison with the increase in Cd-U suggested that almost all Cd absorbed will be excreted into urine.

CONCLUSIONS

Among currently smoking Japanese women, cadmium in urine increased in a manner dependent to the number of cigarettes consumed daily. Thus, smoking is a confounder of Cd-U evaluation even among the population with relatively high dietary Cd burden.

Decreases in urine specific gravity and urinary creatinine in elderly women

OBJECTIVE

To examine the effects of aging on urinary levels of creatinine (CR) and urine specific gravity (SG) among women in a large-scale epidemiology survey.

METHODS

Data on CR and SG in urine, together with smoking habits and menopausal status, were selected from previously established databases and combined with the results of supplemental sample collection. In total, CR and SG data were available for 11,090 never-smoking women (total group; 29-80 years of age); a subgroup of 1,851 women who lived in Kyoto was also selected from the total group. Data from the two groups were subjected to statistical analyses. In statistical evaluation, SG was converted to factor G, which was defined as (SG-1.000)x1,000.

RESULTS

Classification by decade of years of age showed that both CR and SG decreased steadily as a function of advancement in age over 30 years, both in the total group and in the Kyoto subgroup, showing high reproducibility of the observation on a whole-country basis and on a local basis. When the levels at 80 years of age were compared with those at 30 years, there was an approximately 60% and 30% decrease in CR and factor G, respectively. Thus, the effects of aging were more marked on CR than on factor G (and therefore on SG). Menopause appeared to be an influential factor in the reduction of CR and SG, separately from aging itself.

CONCLUSIONS

Urinary levels of creatinine and, to a lesser extent, urine specific gravity, steadily decreased as a function of ages of over 30 years in women.

Effects of aging on cadmium and tubular dysfunction markers in urine from adult women in non-polluted areas

OBJECTIVES

The objectives of the present analyses were to examine if Cd and tubular dysfunction marker levels in urine show age-dependent changes among women who lived in areas with no known cadmium (Cd) pollution in Japan, and if the trends would be further modified by correction of analyte concentration in terms of urinary creatinine (CR or cr) or urine specific gravity (SG or sg).

METHODS

The results of urinalysis for Cd, alpha(1)-microglobulin (alpha(1)-MG), beta(2)-microglobulin (beta(2)-MG), and N-acetyl-beta-D: -glucosaminidase (NAG) concentrations together with CR and SG were cited from previously established databases. A majority of urine samples were collected in 2000-2002 from adult women (mostly at 40-60 years of age) in various areas in Japan, and the collection was supplemented by cases of > or =60-year-old women in 2003. In total, 11,090 never-smoking cases were subjected to statistical analysis. The values as observed (e.g., Cd(ob)), together with after correction for CR (e.g., Cd(cr)) or SG (e.g., Cd(sg)), were examined by linear regression analysis after logarithmic conversion.

RESULTS

The geometric mean (GM) values for Cd were 1.10 microg/l (as observed) or 1.32 microg/g cr (after correction for creatinine concentration). No increases were found in the levels of alpha(1)-MG, beta(2)-MG or NAG on a group basis, in agreement with the conditions that there was no known environmental pollution with Cd in the sampling areas. There were almost linear increases in logarithm of Cd, alpha(1)-MG, beta(2)-MG and NAG concentrations as age advanced. As CR, and to a lesser extent SG, also decreases steadily throughout life, the correction of the analyte concentrations for urine density induced substantial increases in the analyte values; i.e., the correction by CR and SG induced amplification of the increases by two- and 1.4-times, respectively, compared with the increase in non-corrected observed values.

CONCLUSIONS

There were age-related increases in Cd and tubular dysfunction markers in urine among women in areas with no known Cd pollution. The increase was amplified two- or 1.4-times when CR or SG correction was applied, respectively. The observation suggests that care should be practiced in applying CR or SG correction, especially when evaluation of Cd exposure and resulting health effects is made among elderly populations.

Involvement of illegitimate V(D)J recombination or microhomology-mediated nonhomologous end-joining in the formation of intragenic deletions of the Notch1 gene in mouse thymic lymphomas

Deregulated V(D)J recombination-mediated chromosomal rearrangements are implicated in the etiology of B- and T-cell lymphomagenesis. We describe three pathways for the formation of 5'-deletions of the Notch1 gene in thymic lymphomas of wild-type or V(D)J recombination-defective severe combined immune deficiency (scid) mice. A pair of recombination signal sequence-like sequences composed of heptamer- and nonamer-like motifs separated by 12- or 23-bp spacers (12- and 23-recombination signal sequence) were present in the vicinity of the deletion breakpoints in wild-type thymic lymphomas, accompanied by palindromic or nontemplated nucleotides at the junctions. In scid thymic lymphomas, the deletions at the recombination signal sequence-like sequences occurred at a significantly lower frequency than in wild-type mice, whereas the deletions did not occur in Rag2(-/-) thymocytes. These results show that the 5'-deletions are formed by Rag-mediated V(D)J recombination machinery at cryptic recombination signal sequences in the Notch1 locus. In contrast, one third of the deletions in radiation-induced scid thymic lymphomas had microhomology at both ends, indicating that in the absence of DNA-dependent protein kinase-dependent nonhomologous end-joining, the microhomology-mediated nonhomologous end-joining pathway functions as the main mechanism to produce deletions. Furthermore, the deletions were induced via a coupled pathway between Rag-mediated cleavage at a cryptic recombination signal sequence and microhomology-mediated end-joining in radiation-induced scid thymic lymphomas. As the deletions at cryptic recombination signal sequences occur spontaneously, microhomology-mediated pathways might participate mainly in radiation-induced lymphomagenesis. Recombination signal sequence-mediated deletions were present clonally in the thymocyte population, suggesting that thymocytes with a 5'-deletion of the Notch1 gene have a growth advantage and are involved in lymphomagenesis.

Reproducibility of urinary cadmium, alpha1-microglobulin, and beta2-microglobulin levels in health screening of the general population

The present study examined whether levels of cadmium, and alphal- and beta2-microglobulin in urine (Cd-U, ac-MG-U, and beta2-MG-U, respectively) were reproducible in urine samples collected from the same subjects on multiple occasions. For this purpose, two databases on background exposure to cadmium in Japan-one from study I between 2000 and 2001 and the other from study II in 2002-were revisited to find 231 apparently healthy, nonpregnant, nonlactating adult women who participated in both studies and thus had provided two urine samples. The databases contained information on Cd-U, alphal,-MG-U, and beta2-MG-U, creatinine (CR), and specific gravity (SG) as well as smoking and other lifestyle factors. Of the 231 women, 195 who had never smoked were selected for the present analysis. Cd-U as well as alpha1-MG-U were reproducible (e.g., with correlation coefficients [r] between study I and II results of 0.4 to 0.6) when measured on two occasions 9 to 10 months apart. The r values were lower for beta2-MG-U (r0.3). Exclusion of urine samples with inadequate urine density(i.e., CR <0.5 or >3.0 g/L or SG <1.010 or >1.030) resulted in substantial improvement of the agreements between the two measures (e.g., r = 0.6 to 0.7 for Cd-U and alpha1-MG-U). CR and SG correlated closely with each other, especially in low-density urine samples (r >0.9), and therefore the effects of CR and SG could not be evaluated separately. In the overall evaluation,single determination (i.e., without repeated urine sampling) of Cd-U and alpha1-MG-U should be acceptable, and it may also be acceptable for beta2-MG-U. Use of samples with adequate urine density rather than application of density correction to low-density urine samples in recommended.

No effects of hematuria and proteinuria in school days, and probably current pregnancy and current lactation also, as risk factors of cadmium-induced renal tubular dysfunction among adult women in general populations in Japan

This study was initiated to examine if hematuria and proteinuria in school days, current pregnancy, or current lactation are risk factors of cadmium-induced tubular dysfunction for adult women among general populations in Japan. For this purpose, a database of 9,967 never-smoking adult women were reviewed for urinary levels of cadmium (Cd) and three other elements, calcium (Ca), magnesium (Mg), and zinc (Zn), and two tubular dysfunction markers of alpha1-microglobulin (alpha1-MG) and beta2-microglobulin (beta2-MG); the analyte concentrations were corrected for creatinine (cr) and expressed as, e.g., Cd-Ucr. From the total, 160 cases were selected as those who were informed of urinary abnormality (i.e., proteinuria, hematuria, or both) in their school days (the abnormality being found to be transient, later), and each case was matched by age and prefecture of residence. Separately, seven women with persistent urinary abnormality, seven pregnant women, and six lactating women were identified, and the case was matched with three cases each of the same age and living in the same prefecture. Statistical analyses showed that Cd-Ucr and other markers were not elevated in the transient urinary abnormality group as compared with the matched controls. This was also observed in the subjects with persistent abnormality. In the pregnant women, alpha1-MG-Ucr and possibly beta2-MG-Ucr were elevated, but Cd-Ucr did not increase, suggesting that the observed elevation in alpha1-MG and beta2-MG was not due to the effects of Cd but a part of the physiology of pregnancy itself. There was no change in marker levels in lactating women except for an increase in alpha1-MG. In overall evaluation, it was considered prudent to conclude that urinary abnormality in school days does not increase the risk of Cd-induced nephrotoxicity in adult women, whereas the negative findings with pregnancy and lactation should be taken as preliminary because the numbers of cases studied were limited.

α1-Microglobulin as a promising marker of cadmium-induced tubular dysfunction, possibly better than β2-microglobulin

The purpose of the present study was to evaluate the validity of alpha1-microglobulin (alpha1-MG) in comparison with popularly used beta2-microglobulin (beta2-MG). A database on 8975 cases of never-smoking adult women was revisited; the data were based on spot urine samples from the women in 10 prefectures all over Japan. The validity of alpha1-MG was examined following essentially the same protocol as beta2-MG was examined in a previous study. Comparisons were made for alpha1-MG as observed (e.g. alpha1-MG(ob)), as corrected for creatinine (CR or cr) (e.g. alpha1-MGcr) and as corrected for a specific gravity (SG or sg) of 1.016 (e.g. alpha1-MGsg). A cut-off value of 5.0 mg alpha1-MG/g cr or l was deduced from 400 microg beta2-MG/g cr taking advantage of the regression equation between alpha1-MG and beta2-MG. The prevalence of alph1-microglobulinuria as corrected for a specific gravity of 1.016 (or alpha1-MGsg-uria in short) was essentially unchanged irrespective of SG, except for in very dense or very thin urine samples. alpha1-MGcr-uria prevalence decreased at higher CR. Comparison of the present observation with previous findings on beta2-MG-uria prevalence showed that the variation in prevalence of MG-uria as a function of urine density was smaller for alpha1-MGsg whereas it was substantially larger for beta2-MGcr, and thus it appeared prudent to consider alpha1-MGsg rather than beta2-MGcr as a marker of tubular dysfunction.

Benzylmercapturic acid is superior to hippuric acid and o-cresol as a urinary marker of occupational exposure to toluene

The present study was initiated to examine whether urinary benzylmercapturic acid (or N-acetyl-S-benzyl cysteine, BMA), a mercapturate metabolite of toluene, increases in relation to the intensity of toluene exposure, and whether this metabolite is a better marker of occupational exposure to toluene than two traditional markers, hippuric acid and o-cresol. Accordingly, end-of-shift urine samples were collected from 122 printers and 30 office clerks (all men) in the second half of a working week. Solvent (toluene) exposure of the day (8 h) was monitored by means of diffusive sampling. Quantitative relation with toluene showed that BMA had a greater correlation coefficient with toluene (r = 0.7) than hippuric acid (r = 0.6) or o-cresol (r = 0.6). The levels in the urine of the non-exposed control subjects were below the detection limit of 0.2 microg/l for BMA, whereas it was at substantial levels for hippuric acid and o-cresol (239 mg/l and 32 microg/l as a geometric mean, respectively). Thus, BMA, hippuric acid and o-cresol could separate the exposed from the non-exposed when toluene was at < 1, 50 and 3 ppm, respectively. Overall, therefore, it appeared reasonable to conclude that BMA is superior to hippuric acid and o-cresol as a marker of occupational exposure to toluene.

Bias induced by the use of creatinine-corrected values in evaluation of beta2-microgloblin levels

The present study was initiated to examine if the correction for creatinine (CR or cr) is the best approach among the three methods of correction for CR, correction for a specific gravity (SG or sg) and the use of observed values in managing difference in urine density. For this purpose, a database previously developed on 10,753 adult women in 10 non-polluted areas in Japan was re-visited for information on age, urinary levels of Cd, Mg, Ca, Zn, beta(2)-MG, and creatinine, and urine specific gravity as well as smoking habits. Never-smoking women with various urine density counted 8975 cases (the various urine density group). From these cases, 7081 cases with adequate urine density (i.e. 0.5 g/l < or = CR < or = 3.0 g/l and 1.010 < or = SG < or = 1.030) were selected (the adequate urine density group). When a beta(2)-MG level of 400 microg/g CR or 400 microg/l was taken as a cut-off value for beta(2)-MG-uria, both the prevalence of beta(2)-MG(cr)-uria [i.e. cases with beta(2)-MG (as corrected for CR) in excess of 400 microg/g cr] and that of beta(2)-MG(sg)-uria increased as a function of the decrease in Cd(cr) or Cd(sg). The prevalence of beta(2)-MG(ob)-uria also varied as a function of CR and SG, especially of CR, but its range of variation was smaller than the corresponding changes in beta(2)-MG(cr)-uria prevalence. A noteworthy advantage for the use of observed values over that of SG-corrected values was the minimum effect of age. In over-all evaluation, therefore, the recommended approach appeared to be the use of non-corrected observed values (after selection of urine samples for adequate urine density if desired) or correction for SG, rather than correction for CR.

Comparative evaluation of four urinary tubular dysfunction markers, with special references to the effects of aging and correction for creatinine concentration

Comparative evaluation was made on alpha(1)-microglobulin (alpha(1)-MG), beta(2)-microglobulin (beta(2)-MG), retinol binding protein (RBP) and N-acetyl-beta-D-glucosaminidase (NAG), as a marker of renal tubular dysfunction after environmental exposure to cadmium (Cd), with special references to the effects of aging and correction for creatinine concentration. For this purpose, a previously established database of 817 never-smoking Japanese women (at the ages of 20 to 74 years) on hematological [hemoglobin, serum ferritin (FE), etc.] and urinary parameters [alpha(1)-MG, beta(2)-MG, creatinine (cr), and a specific gravity] was revisited. For the present analysis, the database was supplemented by the data on RBP and NAG in urine. The exposure of the women to Cd was such that the geometric mean Cd in urine was 1.3 microg/g cr. Among the four tubular dysfunction markers, NAG showed the closest correlation with Cd, followed by alpha(1)-MG and then beta(2)-MG, and RBP was least so although the correlations were all statistically significant. The observed values of the markers gave the best results, whereas correction for a urine specific gravity gave poorer correlation, and it was the worst when correction for creatinine concentration was applied. Age was the most influential confounding factor. The effect of age appeared to be attributable at least in part to the fact that both creatinine and, to a lesser extent, the specific gravity decreased as a function of age. Iron deficiency anemia of sub-clinical degree as observed among the women did not affect any of the four tubular dysfunction markers. In conclusion, NAG and alpha(1)-MG, rather beta(2)-MG or RBP, are more sensitive to detect Cd-induced tubular dysfunction in mass screening. The use of uncorrected observed values of the markers rather than traditional creatinine-corrected values is recommended when comparison covers people of a wide range of ages.

Radiation-induced deletions in the 5' end region of Notch1 lead to the formation of truncated proteins and are involved in the development of mouse thymic lymphomas

Notch1 protein is a transmembrane receptor that directs various cell fate decisions. Active forms of Notch1 consisting of a transmembrane domain and an intracellular domain (Notch1TM) or only an intracellular domain (Notch1IC) function as oncoproteins. To elucidate the effect of Notch1 abnormalities in radiation-induced lymphomagenesis, we determined the structure of the Notch1 gene and examined the frequency and the sites of Notch1 rearrangements in radiation-induced mouse thymic lymphomas. The Notch1 gene consists of 37 exons, including three exons upstream of the previously reported exon 1. The transcript starting from exon 1 was the major transcript whereas the transcripts read upstream from exon 1a, in which amino acid sequences in the N-terminal region were changed, were minor. More than 50% of radiation-induced thymic lymphomas exhibited Notch1 rearrangements, suggesting that Notch1 acts as a major oncogene in radiation-induced lymphomagenesis. We identified three rearranged sites: novel sites in the 5' end region encompassing exons 1 and 2, the previously identified juxtamembrane extracellular region, and the 3' end region. The 5' deletion and the insertion of murine leukemia virus in the juxtamembrane region led to the production of abnormal transcripts starting from cryptic transcription start sites located halfway through the Notch1 gene and resulted in transcripts lacking most of the extracellular domain. As a result of these rearrangements, truncated Notch1 polypeptides resembling Notch1TM or Notch1IC were formed. In contrast, the 3' deletion led to the production of a C-terminal PEST motif-deleted transcript. The downstream target gene Hes1 was transcribed in a lymphoma with insertion of murine leukemia virus, but not in a lymphoma with a 5' deletion. These results indicate that in addition to Hes1 expression, other Notch1 pathway(s) have a role in thymic lymphomagenesis and suggest the presence of a novel mechanism for oncogenic activation of Notch1 by 5' deletion.

Formation of an active form of the interleukin-2/15 receptor beta-chain by insertion of the intracisternal A particle in a radiation-induced mouse thymic lymphoma and its role in tumorigenesis

Although many reports suggest that aberrant regulation of cytokine signaling pathways via the interleukin-2 receptor (IL-2R) induces tumorigenic transformation, constitutively active IL-2R in tumors has not been reported. We searched for genomic alteration of the IL-2/15R beta-subunit gene (IL-2/15R beta) in cytokine-independent cell lines established from radiation-induced mouse thymic lymphomas. In the TL34 cell line and its primary tumor, one of the IL-2/15R beta alleles was rearranged by the insertion of an intracisternal A particle (IAP) retrotransposon. The IAP-IL2/15R beta chimeric gene expressed chimeric mRNA in which IAP-coding Gag-Pol mRNA was fused to IL-2/15R beta mRNA and coded for Gag-Pol-IL-2/15R beta chimeric protein. Forced expression of the Gag-Pol-IL-2/15R beta chimeric cDNA in a mouse cytotoxic T-cell line (CTLL-2) converted IL-2-dependent cell growth to IL-2-independent growth, suggesting that the chimeric protein activates some of the IL-2 signaling pathways necessary for cell proliferation. Downregulation of the expression of the Gag-Pol-IL-2/15R beta chimeric protein in TL34 by antisense RNA inhibited cell growth, and concomitantly reduced the level of c-myc protein. These results suggest that the Gag-Pol-IL-2/15R beta is a constitutively active form that transmits proliferative signals by expressing downstream target genes, including c-myc. Thus, we demonstrated that the chimeric receptor gene produced by the insertion of an IAP functions as an oncogene by providing IL-2-independent autonomous growth potential.

No significant effect of iron deficiency on cadmium body burden or kidney dysfunction among women in the general population in Japan

OBJECTIVE

To examine if iron-deficient conditions modify body burden or health effects of cadmium among women in the general population in Japan.

METHODS

In 2002, 1,482 women aged 20 to 74 years in six prefectures in Japan provided informed consent to participate in this study. They offered peripheral blood and spot urine samples, and answered questionnaires on their social habits and health conditions. Never-smoking, non-pregnant and non-lactating healthy women (1,190 subjects) were selected from the volunteers. Blood samples were analyzed for serum iron, ferritin and total iron-binding capacity (TIBC) in addition to red blood cell (RBC) counts and hemoglobin (Hb) concentration as markers of anemia and iron deficiency. Urine samples were analyzed for cadmium (Cd), alpha(1)-microglobulin (alpha(1)-MG), beta(2)-microglobulin (beta(2)-MG) as markers of Cd burden and Cd-induced tubular dysfunction; the measures were expressed after being corrected for creatinine (cr) as, e.g., Cd-Ucr.

RESULTS

The subjects were classified into anemic (37 women) and iron-deficient (388 women) groups separately from healthy controls (765 women), taking ferritin (<20 ng/ml) and Hb (<10 g/100 ml) as classification indicators. Strictly matched pairs (with regard to age and prefecture) were established for 36 anemic and 280 iron-deficient cases. Comparison between the cases and the matched controls showed that serum iron was lower and TIBC was higher in accordance with lower levels of ferritin and Hb in the anemic and iron-deficient groups, although the RBC count was only slightly reduced (the anemic group) or stayed essentially unchanged (the iron-deficient group). In contrast, no significant increase in Cd-Ucr, alpha(1)-MG, or beta(2)-MG was observed in either the anemic group or the iron-deficient group compared with the matched controls. Cd-Ucr in one case of clinical anemia, however, tended to be higher than the levels among women of the same age range and from the same prefecture. Her alpha(1)-MG-Ucr and beta(2)-MG-Ucr, however, remained un-elevated.

CONCLUSIONS

The current level of iron deficiency among women in the general population in Japan may not induce significant increase in Cd body burden or Cd-induced tubular dysfunction.

No clear-cut evidence for cadmium-induced renal tubular dysfunction among over 10,000 women in the Japanese general population: a nationwide large-scale survey

OBJECTIVE

To examine whether environmental exposure to cadmium has been inducing kidney dysfunction among middle-aged women in the general population in Japan.

METHODS

This study was conducted in 2000 and 2001. Morning spot urine samples were collected from 10,753 women (mostly aged 35 to 60 years) in ten prefectures all over Japan (thus about 1,000 women per site). Urine samples were analyzed for cadmium (Cd-U), calcium (Ca-U), magnesium (Mg-U), zinc (Zn-U), alpha(1)- and beta(2)-microglobulins (alpha(1)- and beta(2)-MG-U). The urinary analyte concentrations were corrected for creatinine (cr) concentration (i.e., Ucr). The data thus obtained were subjected to statistical evaluation by chi-square test, ANOVA, multiple comparison test, and simple regression analysis (SRA) as well as multiple regression analysis (MRA) including logistic regression analysis (LRA). Log-normal distribution was assumed for Cd-Ucr, alpha(1)-MG-Ucr and beta(2)-MG-Ucr, whereas normal distribution was considered for age, Ca-Ucr, Mg-Ucr and Zn-Ucr.

RESULTS

Geometric mean values (GM) of Cd-Ucr were distributed unevenly, depending on the sampling areas, with a grand GM of 1.3 microg/g cr, the highest (3.2 microg/g cr) and lowest GM values(0.8 microg/g cr) being significantly different from GMs of other areas. Correlation matrix analysis with subjects of all ages showed that log alpha(1)-MG-Ucr and log beta(2)-MG-Ucr correlated significantly (r=0.272 and 0.202, respectively) with log Cd-Ucr, but they correlated also with age (r=0.280 and 0.213, respectively). The same analysis with the two selected age groups (41-50 and 51-60 years), however, failed to show close correlation of alpha(1)-MG-Ucr and log beta(2)-MG-Ucr with Cd-Ucr. Both MRA and LRA indicated that age was a confounding factor in the evaluation of the effect of Cd-U on the two MG levels. Whereas the LRA with the all-age group showed a positive influence of log Cd-Ucr on log alpha(1)-MG-Ucr and log beta(2)-MG-Ucr, such effect disappeared in parallel with the disappearance of age effects when LRA was conducted with the two selected age groups. An exceptional observation was the influence of log Cd-Ucr on log alpha(1)-MG-Ucr (but not on log beta(2)-MG-Ucr) in LRA when a cut-off value of 5.00 mg for alpha(1)-MG-U/g cr was applied. Comparison between the low and high Cd-U groups showed that both alpha(1)-MG-Ucr and beta(2)-MG-Ucr were higher in the high Cd-U groups, but prevalence of cases with alpha(1)-MG-Ucr and beta(2)-MG-Ucr in excess of the cut-off values did not differ between the two groups except when a cut-off value of 5.00 mg/g cr was employed for alpha(1)-MG-U.

CONCLUSIONS

In over-all evaluation, no clear-cut evidence was obtained in the present study to show that environmental exposure to Cd has induced tubule dysfunction among middle-aged women in the general population in Japan. It might be the case, however, that an increase in alpha(1)-MG-U was associated with Cd exposure. In this sense, it is apparently desirable from public health viewpoints to make further efforts to reduce the intensity of the general population's exposure to environmental Cd.

Analysis for threshold levels of cadmium in urine that induce tubular dysfunction among women in non-polluted areas in Japan

OBJECTIVE

To examine if there is a threshold in urinary cadmium concentration that induces elevation in urinary microglobulins.

METHODS

The database developed in a previous field survey (Ezaki et al. 2002) was employed. In the survey conducted in 2000 and 2001, more than 10,000 middle-aged women (with no occupational exposure to Cd) in ten prefectures all over Japan gave morning spot urine samples, which were analyzed for cadmium (Cd-U), calcium (Ca-U), magnesium (Mg-U), zinc (Zn-U), alpha(1)- and beta(2)-microglobulins (alpha(1)- and beta(2)-MG-U), and creatinine (cr). The urinary analyte concentrations were corrected for cr concentration (to be expressed as, e.g., Cd-Ucr), and the data thus obtained were subjected to statistical evaluation. The largest geometric mean (GM) for Cd-Ucr among the ten prefecture was 3.2 microg Cd/g cr, and the maximum Cd-Ucr observed among the women studied was 20.9 microg Cd/g cr.

RESULTS

Both alpha(1)-MG-Ucr and beta(2)-MG-Ucr increased as a function of the increase in Cd-Ucr among all the women and also in sub-populations of narrow age ranges (i.e., 41-50 and 51-60 years), with no apparent threshold Cd-Ucr. Comparison of the cases exceeding cut-off alpha(1)-MG-Ucr and beta(2)-MG-Ucr levels also indicated a Cd dose-dependent increase in the prevalence, similarly without a threshold Cd-Ucr. In addition, such findings were essentially reproducible when elevation in alpha(1)-MG-Ucr and beta(2)-MG-Ucr levels was examined with the three essential elements, especially with Ca-Ucr and Mg-Ucr, although less clearly with Zn-Ucr. The observations as a whole suggest a possibility that the dose-dependent increases in alpha(1)-MG-Ucr and beta(2)-MG-Ucr with no apparent threshold for element concentration is not specific to Cd-Ucr but common to other elements.

CONCLUSIONS

No threshold Cd-Ucr was detected in relation to the increases in alpha(1)-MG-Ucr and beta(2)-MG-Ucr. The element dose-dependent increases in the two MGs with no threshold in the element concentration might be not limited to Cd, but common to other elements. Further studies are apparently necessary.

Threshold levels of urinary cadmium in relation to increases in urinary beta2-microglobulin among general Japanese populations

Through literature survey, paired data on cadmium (Cd) and beta(2)-microglobulin (beta(2)-MG) levels (as corrected for creatinine concentration) in urine (i.e., Cd-Ucr and beta(2)-MG-Ucr) among Japanese populations were available for 32 groups of men and 58 groups of women in 12 publications. Plotting of the Cd-Ucr and beta(2)-MG-Ucr data for the groups of women showed that beta(2)-MG-Ucr stayed unchanged when Cd-Ucr was at lower levels, whereas beta(2)-MG-Ucr increased sharply when Cd-Ucr was in excess of 10-20 microg/g cr. Regression analysis was made for groups of women with no elevation in beta(2)-MG-Ucr, and those with >400 or >1000 microg beta(2)-MG-U/g cr. A threshold Cd-Ucr level in relation to an increase in beta(2)-MG-Ucr was estimated as Cd-Ucr at the point of intercept of the two regression lines, one with no beta(2)-MG-Ucr elevation, and the other with >400 or >1000 microg beta(2)-MG-U/g cr. Cd-Ucr at the point of flexion thus calculated was 11-12 microg/g cr. Such observation was quantitatively reproduced by the analysis of data for men, giving 10-11 microg Cd-U/g cr at the point of flexion. This study suggests that the relationship of beta(2)-MG-Ucr with Cd-Ucr is not linear but in the shape of letter 'J', i.e., beta(2)-MG-Ucr increases sharply when Cd-Ucr is in excess of 10-12 microg/g cr.

A new technique to prevent self-ligation of DNA

The most widely used technique for preventing self-ligation (self-circularization and concatenation) of DNA is dephosphorylation of the 5'-end, which stops DNA ligase from catalyzing the formation of phosphodiester bonds between the 3'-hydroxyl and 5'-phosphate residues at the DNA ends. The 5'-dephosphorylation technique cannot be applied to both DNA species to be ligated and thus, the untreated DNA species remains capable of self-ligation. To prevent this self-ligation, we replaced the 2'-deoxyribose at the 3'-end of the untreated DNA species with a 2',3'-dideoxyribose. Self-ligation was prevented at the replaced 3'-end, while the 5'-phosphate remaining at the 5'-end permitted ligation with the 3'-hydroxyl end of the 5'-dephosphorylated DNA strand. We successfully applied this 3'-replacement technique to gene cloning, adapter-mediated polymerase chain reaction and messenger RNA fingerprinting. The 3'-replacement technique is simple and not restricted by sequence or conformation of the DNA termini and is thus applicable to a wide variety of methods involving ligation.

Absence of linkage between radiosensitivity and the predisposing atp7b gene mutation for heritable hepatitis in the LEC rat

The LEC rat is known to be a mutant strain that spontaneously develops heritable hepatitis due to copper accumulation, caused by mutation of the copper-transporting ATPase gene (Atp7b). Immunodeficiency and radiosensitivity have also been observed. Hayashi et al. extensively examined the radiosensitivity of the LEC rat and concluded that its hypersensitivity is controlled by a single autosomal gene. Furthermore, they suggested the possibility that it correlates to copper accumulation due to the Atp7b gene mutation, because ionizing radiation-induced hydroxyl radicals might act in concert with copper-induced hydroxyl radicals. In the present experiment, we analyzed linkage between radiosensitivity and the mutation responsible for hepatitis in F(1) animals of a cross with the F344 rat. Our results clearly demonstrated an absence of any significant association. In addition, partial dominance for radiosensitivity was observed, and radiosensitive (F(1) x LEC) backcross rats were twice as numerous as their radioresistant counterparts, suggesting the possibility of control by two or more recessive genes.

Monitoring of occupational exposure to tetrachloroethene by analysis for unmetabolized tetrachloroethene in blood and urine in comparison with urinalysis for trichloroacetic acid

OBJECTIVE

The present study was initiated to examine a quantitative relationship between tetrachloroethene (TETRA) in blood and urine with TETRA in air, and to compare TETRA in blood or urine with trichloroacetic acid (TCA) in urine as exposure markers.

METHODS

In total, 44 workers (exposed to TETRA during automated, continuous cloth-degreasing operations), and ten non-exposed subjects volunteered to participate in the study. The exposure to vapor was monitored by diffusive sampling. The amounts of TETRA and TCA in end-of-shift blood and urine samples were measured by either head-space gas chromatography (HS-GC) or automated methylation followed by HS-GC. The correlation was examined by regression analysis.

RESULTS

The maximum time-weighted average (TWA) concentration for TETRA-exposure was 46 ppm. Regression analysis for correlation of TETRA in blood, TETRA in urine and TCA in urine, with TETRA in air, showed that the coefficient was largest for the correlation between TETRA in air and TETRA in blood. The TETRA in blood, in urine and in air correlated mutually, whereas TCA in urine correlated more closely with TETRA in blood than with TETRA in urine. The TCA values determined by colorimetry and by the GC method were very similar. The biological marker levels at a hypothetical exposure of 25 ppm TETRA were substantially higher in the present study than were the levels reported in the literature. Possible reasons are discussed.

CONCLUSIONS

Blood TETRA is the best marker of occupational exposure to TETRA, being superior to the traditional marker, urinary TCA.

Blood lead level to induce significant increase in urinary delta-aminolevulinic acid level among lead-exposed workers: a statistical approach

The present study was initiated to examine the quantitative relationship between blood lead (Pb-B) and urinary delta-aminolevulinic acid (ALA-U) among Pb-exposed workers, and to find a threshold Pb-B level to induce an increase in ALA-U. For this purpose, pairs of venous blood and spot urine samples were collected from 8,274 men and 5,856 women (14,130 workers in total) who were occupationally exposed to inorganic lead. The blood and urine samples were analyzed for Pb-B and ALA-U by atomic absorption spectrometry and colorimetry, respectively, and the correlation between pairs of measures were subjected to statistical analysis. The assumption of the 3rd degree regression for correlation gave a substantially greater correlation coefficient (0.645 for men and 0.619 for women) than 1st or 2nd degree regression, whereas only very small improvement in the coefficient was achieved with 4th to 6th degree ones. Logarithmic conversion of the parameters was not effective in improving the correlation. The assumption of the 3rd degree regression followed by calculation of the local minimum gave 22, 29 and 23 micrograms/100 ml Pb-B for men, women, and men + women, respectively, as the threshold Pb-B to induce ALA-U increase. Pb-B to elevate ALA-U to the 95% upper normal limit (8 mg/l, common to men and women) was 62, 50 and 58 micrograms/100 ml for men, women and men + women, respectively. The validity of the 3rd degree regression assumption as a tool to calculate a threshold from experimental or epidemiological data is discussed.

Three-dimensional bone response to commercially pure titanium, hydroxyapatite, and calcium-ion-mixing titanium in rabbits

Three-dimensional bone response to 3 biomaterials--commercially pure titanium (Ti), hydroxyapatite (HA), and calcium-ion-mixing titanium (Ca-Ti)--embedded in the tibiae of rabbits was examined chronologically. The rabbits were sacrificed at 2, 4, and 8 weeks after implantation, and the percent bone volume around each implant was calculated from the implant surface to each of 4 measurements: 36 microns, 0.25 mm, 0.5 mm, and 1.0 mm in 2 regions (cortical bone and bone marrow regions). Percent bone volume in the cortical bone was consistent, whereas in the bone marrow region, the percent bone volume varied according to implant material, implantation period, and distance from the implant surface. With Ti implants the percent increased gradually up to 8 weeks at each distance, whereas in HA and Ca-Ti implants the percent was largest at 4 weeks and increased closer to the surface. The percent with Ti implants was largest at 36 microns to 0.25 mm. Aspect of bone response to Ca-Ti was its position intermediate between those of HA and Ti. The decrease of the percent at 8 weeks was smaller than HA.

Urinary lead as a possible surrogate of blood lead among workers occupationally exposed to lead

OBJECTIVES

The aim of the present study is to investigate whether lead (Pb) in urine (Pb-U) can be a valid surrogate of lead in blood (Pb-B), the traditional biomarker of exposure to lead in occupational health.

METHODS

Blood and spot urine samples were collected from 258 workers of both sexes occupationally exposed to lead. The samples were analyzed for lead by graphite furnace atomic absorption spectrometry, and the correlation between Pb-B and Pb-U was examined by linear regression analysis before and after logarithmic conversion.

RESULTS

The correlation coefficient (0.824; P < 0.01) was largest when the relationship between Pb-B and Pb-U was examined with 214 cases of one sex (i.e., men) after Pb-U was corrected for a specific gravity (1.016) of urine (Pb-Usg) and both Pb-B and Pb-Usg were converted to logarithms. The geometric means (GMs) of Pb-B and Pb-Usg for the 214 men were 489 microG/l and 81 microg/l, respectively. When Pb-Usg was assumed to be 100 microg/l in this set of correlations, the 95% confidence range of Pb-B for the group mean was narrow, i.e., 543-575 microg/l (with GM of 559 microg/l), whereas that for individual Pb-B values was as wide as 355-881 microg/l.

CONCLUSIONS

The correlation of Pb-U with Pb-B among workers occupationally exposed to Pb was close enough to suggest that Pb-U may be a good alternative to Pb-B on a group basis, but not close enough to allow Pb-U to predict Pb-B on an individual basis.

Monitoring of occupational exposure to dichloromethane by diffuse vapor sampling and urinalysis

OBJECTIVE

The aim of the present study was to develop valid methods for monitoring of occupational exposure to dichloromethane (DCM).

METHODS

Carbon cloth as an adsorbent in diffusive sampling was tested for its capacity to adsorb DCM vapor and to retain adsorbed DCM after termination of the exposure. Urine samples collected from DCM-exposed workers were analyzed for DCM by the head-space technique. After extraction with carbon disulfide, DCM in the cloth was analyzed on a DB-WAX capillary column by flame-ionization detection gas chromatography (FID-GC) and DCM in urine was analyzed by electron-capture detection (ECD)-GC.

RESULTS

The diffusive sampling with carbon cloth as an adsorbent is applicable to 4-h monitoring of exposure to up to 100 ppm DCM vapor. DCM concentrations detected in end-of-shift urine samples correlated linearly with time-weighted average DCM concentrations measured in the breathing-zone air of the exposed workers; essentially the same exposure-excretion relationship was obtained by vapor monitoring for the afternoon 4-h period as compared with a whole day (8-h) of vapor monitoring. There was no sex difference in the exposure-excretion relation.

CONCLUSIONS

Both personal diffusive sampling (at up to 100 ppm DCM and for up to 4 h) and biological exposure monitoring by urinalysis for DCM are applicable in occupational health as reliable measures of exposure to this chlorinated hydrocarbon solvent.

ftsE(Ts) affects translocation of K+-pump proteins into the cytoplasmic membrane of Escherichia coli

The ftsE(Ts) mutation of Escherichia coli causes defects in cell division and cell growth. We expressed alkaline phosphatase (PhoA) fusion proteins of KdpA, Kup, and TrkH, all of which proved functional in vivo as K+ ion pumps, in the mutant cells. During growth at 41 degrees C, these proteins were progressively lost from the membrane fraction. The reduction in the abundance of these proteins inversely correlated with cell growth, but the preformed proteins in the membrane were stable at 41 degrees C, indicating that the molecules synthesized at the permissive temperature were diluted in a growth-dependent manner at a high temperature. Pulse-chase experiments showed that KdpA-PhoA was synthesized, but the synthesized protein did not translocate into the membrane of the ftsE(Ts) cells at 41 degrees C and degraded very rapidly. The loss of KdpA-PhoA from the membrane fractions of ftsE(Ts) cells was suppressed by a multicopy plasmid carrying the ftsE+ gene. While cell growth stopped when the abundance of these proteins decreased 15-fold, the addition of a high concentration of K+ ions specifically alleviated the growth defect of ftsE(Ts) cells but not cell division, and the cells elongated more than 100-fold. We conclude that one of the causes of growth cessation in the ftsE(Ts) mutants is a defect in the translocation of K+-pump proteins into the cytoplasmic membrane.

High-pressure liquid chromatographic determination of toluene in urine as a marker of occupational exposure to toluene

OBJECTIVE

To establish a convenient method by high-pressure liquid chromatography (HPLC) to measure toluene in urine as a marker of occupational exposure to toluene.

METHODS

As soon after sampling as possible, 1 ml of urine was mixed with an equal volume of acetonitrile in a 2.2-ml HPLC glass bottle, and the bottle was tightly sealed and stored at 4 degrees C. Immediately before HPLC determination, 100 microl methanol was added to the mixture to prevent confounding effects of glycosuria, and the bottle was spun to remove any suspended matter. An aliquot of the supernate was introduced into the HPLC system and analyzed on a PRODIGY column, with an acetonitrile - perchloric acid phosphoric acid - water mixture serving as the mobile phase. The effluent was monitored at 191 nm.

RESULTS

The method can measure toluene in urine every 20 min, the detection limit was 2 microg/l, the coefficient of variation was less than 5%, and the recovery rate was 100%. No significant reduction in toluene concentration was observed for 1 week after storage at 4 degrees C. When the method was applied to end-of-shift urine samples from 13 male workers exposed to toluene at 18-140 ppm and also to urine samples from 10 nonexposed male controls, toluene in urine was linearly related to toluene exposure concentration, with a regression line passing close to the origin. The correlation coefficient was as high as 0.97 (n=23). No toluene was detected in control urine samples. Calculations suggest that urinary toluene accounts for as little as less than 0.01% of the toluene absorbed via inhalation and that the absorbed toluene is converted almost quantitatively to hippuric acid and, by less than 0.1%, to o-cresol.

[Diagnosis of the wall-thickened lesions of the gallbladder with dynamic MRI]

We studied 32 patients with the thickened lesions of the wall of the gallbladder by using dynamic MRI. We tried the differential diagnosis of gallbladder lesions according to the time intensity curve (TIC) and enhanced pattern. TIC of carcinoma was elevated more seeply from plain to arterial phase than the inflammatory diseases. The Inflammatory diseases were keeping three-layer structures of the wall of the gallbladder, but gallbladder carcinoma destroys the wall-structure. We could diagnose as direct liver invasion of the carcinoma clearly. We could exactly diagnose adenomyomatosis in dynamic MRI by small low intensity spots within the wall of the gallbladder. In the patients with gall stones, the wall of the gallbladder were more clearly observed in dynamic MRI compared with US and EUS.

Endoscopic MRI

We used a new magnetic resonance endoscope with a small radiofrequent (RF) coil attached to the tip. After insertion of the instrument into the second portion of the duodenum, patients were placed in a magnetic resonance imaging (MRI) scanner. Fast spoiled gradient-recalled acquisition (SPGR) pulse sequences were used for this method. After plain scans, six axial scans were performed after intravenous injection of 20 ml of gadolinium-diethylenetriaminepentaacetic acid (DTPA) contrast medium. We performed endo-MRI on 22 patients, 13 with pancreatic carcinoma, four with pancreatic cystoadenoma, and five with other diseases. In the patients with pancreatic carcinoma, tumors were delineated as low-intensity masses after injection of contrast medium. Dilated main pancreatic ducts were clearly defined. In eight patients with carcinoma of the head of the pancreas, tumors were clearly defined in seven (87.5%) cases. In the eighth case, motion artifact prevented acquisition of a clear image of the pancreas. For diagnosis of invasion of the portal vein, the sensitivity of endo-MRI was 80%, the specificity was 100%, and overall accuracy was 87.5%. The new technique of endo-MRI allows the precise diagnosis of pancreatic tumors.

Variation in the ratio of respirable particulates over inhalable particulates by type of dust workplace

OBJECTIVE

The aim of the present study was to clarify the quantitative relationship between respirable particulates and inhalable particulates in various dust workplaces.

METHODS

Both respirable particulate and inhalable particulate concentrations were measured in 1644 dust workplaces by means of elutriation, and the ratio of respirable particulate mass over that of inhalable particulate (R/I ratio) was calculated for each workplace.

RESULTS

Statistical analyses showed that the R/I ratio varied substantially, depending on the type of dust work. The ratio was highest in welding workplaces (mean +/- SD: 53 +/- 19%) and lowest in foundries (23 +/- 16%); the former value suggests that respirable particulate exposure may be underestimated in substantial parts of welding work when only the occupational exposure limit for inhalable particulates is taken for compliance testing.

CONCLUSIONS

Simple compliance with the limit for inhalable particulates is not sufficient, and the limit for respirable particulates should also be simultaneously cleared.