Translocation of ultrafine insoluble iridium particles from lung epithelium to extrapulmonary organs is size dependent but very low

Recently it was speculated that ultrafine particles may translocate from deposition sites in the lungs to systemic circulation. This could lead to accumulation and potentially adverse reactions in critical organs such as liver, heart, and even brain, consistent with the hypothesis that ultrafine insoluble particles may play a role in the onset of cardiovascular diseases, as growing evidence from epidemiological studies suggests. Ultrafine (192)Ir radio-labeled iridium particles (15 and 80 nm count median diameter) generated by spark discharging were inhaled by young adult, healthy, male WKY rats ventilated for 1 h via an endotracheal tube. After exposure, excreta were collected quantitatively. At time points ranging from 6 h to 7 d, rats were sacrificed, and a complete balance of (192)Ir activity retained in the body and cleared by excretion was determined gamma spectroscopically. Thoracic deposition fractions of inhaled 15- and 80-nm (192)Ir particles were 0.49 and 0.28, respectively. Both batches of ultrafine iridium particles proved to be insoluble (<1% in 7 d). During wk 1 after inhalation particles were predominantly cleared via airways into the gastrointestinal tract and feces. This cleared fraction includes particles deposited in the alveolar region. Additionally, minute particle translocation of <1% of the deposited particles into secondary organs such as liver, spleen, heart, and brain was measured after systemic uptake from the lungs. The translocated fraction of the 80-nm particles was about an order of magnitude less than that of 15-nm particles. In additional studies, the biokinetics of ultrafine particles and soluble (192)Ir was studied after administration by either gavage or intratracheal instillation or intravenous injection. They confirmed the low solubility of the particles and proved that (1) particles were neither dissolved nor absorbed from the gut, (2) systemically circulating particles were rapidly and quantitatively accumulated in the liver and spleen and retained there, and (3) soluble (192)Ir instilled in the lungs was rapidly excreted via urine with little retention in the lungs and other organs. This study indicates that only a rather small fraction of ultrafine#10; iridium particles has access from peripheral lungs to systemic circulation and extrapulmonary organs. Therefore, the hypothesis that systemic access of ultrafine insoluble particles may generally induce adverse reactions in the cardiovascular system and liver leading to the onset of cardiovascular diseases needs additional detailed and differentiated consideration.

Pulmonary and systemic distribution of inhaled ultrafine silver particles in rats

The cardiovascular system is currently considered a target for particulate matter, especially for ultrafine particles. In addition to autonomic or cytokine mediated effects, the direct interaction of inhaled materials with the target tissue must be examined to understand the underlying mechanisms. In the first approach, pulmonary and systemic distribution of inhaled ultrafine elemental silver (EAg) particles was investigated on the basis of morphology and inductively coupled plasma mass spectrometry (ICP-MS) analysis. Rats were exposed for 6 hr at a concentration of 133 microg EAg m(3) (3 x 10(6) cm(3), 15 nm modal diameter) and were sacrificed on days 0, 1, 4, and 7. ICP-MS analysis showed that 1.7 microg Ag was found in the lungs immediately after the end of exposure. Amounts of Ag in the lungs decreased rapidly with time, and by day 7 only 4% of the initial burden remained. In the blood, significant amounts of Ag were detected on day 0 and thereafter decreased rapidly. In the liver, kidney, spleen, brain, and heart, low concentrations of Ag were observed. Nasal cavities, especially the posterior portion, and lung-associated lymph nodes showed relatively high concentrations of Ag. For comparison, rats received by intratracheal instillation either 150 microL aqueous solution of 7 microg silver nitrate (AgNO(3) (4.4 microg Ag) or 150 microL aqueous suspension of 50 microg agglomerated ultrafine EAg particles. A portion of the agglomerates remained undissolved in the alveolar macrophages and in the septum for at least 7 days. In contrast, rapid clearance of instilled water-soluble AgNO(3) from the lung was observed. These findings show that although instilled agglomerates of ultrafine EAg particles were retained in the lung, Ag was rapidly cleared from the lung after inhalation of ultrafine EAg particles, as well as after instillation of AgNO(3), and entered systemic pathways.

DNA sensing on a DNA probe-modified electrode using ferrocenylnaphthalene diimide as the electrochemically active ligand

Naphthalene diimide derivative 1 carrying ferrocenyl moieties at the termini of imide substituents binds intact calf thymus DNA 4 times more strongly than the denatured DNA, and its complex with the intact DNA dissociates 80 times more slowly than that with the denatured DNA. On the basis of these observations, ligand 1 was applied to a probe of electrochemical DNA sensing. A thiol-linked single-stranded DNA probe was immobilized through the S-Au bonding to 20-30 pmol/mm2 on a gold electrode. Following hybridization with the complementary DNA, the electrode was soaked in a solution containing 1 (intercalation step) and then washed with buffer for 5 s. The cyclic voltammogram and differential pulse voltammogram for this electrode gave an electrochemical signal due to the redox reaction of 1 that was bound to the double-stranded DNA on the electrode. Thus, dA20 and the yeast choline transport gene were quantitated at the subpicomole level. The sensitivity of DNA detection was improved to 10 zmol by reducing the amount of immobilized DNA probe and protecting the uncovered surface of the electrode with 2-mercaptoethanol.

Chronic effects on the respiratory tract of hamsters, mice and rats after long-term inhalation of high concentrations of filtered and unfiltered diesel engine emissions

A long-term exposure study with hamsters, mice and rats inhaling filtered and unfiltered diesel engine exhaust was carried out to investigate effects of chronic toxicity and, predominantly, carcinogenicity in the respiratory tract. The level of diesel exhaust in the exposure chambers corresponded to a concentration close to 4 mg m-3 in the unfiltered diesel exhaust. Satellite groups of animals were additionally treated with BaP, DBahA or nitrosamines in order to check for syncarcinogenic effects. In hamsters and rats, alveolar lung clearance and mechanical lung function tests as well as biochemical and cytological measurements in lung lavage fluids showed significant changes only after exposure to unfiltered diesel exhaust and, predominantly, in rats. No lung tumors were found in hamsters. Spontaneous tumor rates occurred in mice and both types of diesel exhaust increased the incidence of adenocarcinomas in the lungs. In rats, only the unfiltered diesel exhaust caused a lung tumor incidence. It amounted to 16% with no tumors in the controls. The heavy load of particulate matter in the lungs of rats was caused by an exposure-related impairment of the alveolar lung clearance and may have been instrumental in the induction of squamous cell tumors. However, an effect of particle-associated PAH cannot be excluded. Syncarcinogenic effects of diesel exhaust after initial carcinogen treatment were found only in the respiratory tract of rats.

Distribution pattern of inhaled ultrafine gold particles in the rat lung

The role of alveolar macrophages in the fate of ultrafine particles in the lung was investigated. Male Wistar-Kyoto rats were exposed to ultrafine gold particles, generated by a spark generator, for 6 h at a concentration of 88 microg/m3 (4 x 10(6)/cm3, 16 nm modal mobility diameter). Up to 7 days, the animals were serially sacrificed, and lavaged cells and lung tissues were examined by transmission electron microscopy. The gold concentration/content in the lung, lavage fluid, and blood was estimated by inductively coupled plasma-mass spectrometry. Gold particles used were spherical and electron dense with diameters of 5-8 nm. The particles were individual or slightly agglomerated. By inductively coupled plasma-mass spectrometry analysis of the lung, 1945 +/- 57 ng (mean +/- SD) and 1512 +/- 184 ng of gold were detected on day 0 and on day 7, respectively, indicating that a large portion of the deposited gold particles was retained in the lung tissue. In the lavage fluid, 573 +/- 67 ng and 96 +/- 29 ng were found on day 0 and day 7, respectively, which means that 29% and 6% of the retained gold particles were lavageable on these days. A low but significant increase of gold (0.03 to 0.06% of lung concentration) was found in the blood. Small vesicles containing gold particles were found in the cytoplasm of alveolar macrophages. In the alveolar septum, the gold particles were enclosed in vesicles observed in the cytoplasm of alveolar type I epithelial cells. These results indicate that inhaled ultrafine gold particles in alveolar macrophages and type I epithelial cells are processed by endocytotic pathways, though the uptake of the gold particles by alveolar macrophages is limited. To a low degree, systemic particle translocation took place.

Ferrocene-oligonucleotide conjugates for electrochemical probing of DNA

Toward the development of a universal, sensitive and convenient method of DNA (or RNA) detection, electrochemically active oligonucleotides were prepared by covalent linkage of a ferrocenyl group to the 5'-aminohexyl-terminated synthetic oligonucleotides. Using these electrochemically active probes, we have been able to demonstrate the detection of DNA and RNA at femtomole levels by HPLC equipped with an ordinary electrochemical detector (ECD) [Takenaka,S., Uto,Y., Kondo,H., Ihara,T. and Takagi,M. (1994) Anal. Biochem., 218, 436-443]. Thermodynamic and electrochemical studies of the interaction between the probes and the targets are presented here. The thermodynamics obtained revealed that the conjugation stabilizes the triple-helix complexes by 2-3 kcal mol-1 (1-2 orders increment in binding constant) at 298 K, which corresponds to the effect of elongation of additional several base triplets. The main cause of this thermodynamic stabilization by the conjugation is likely to be the overall conformational change of whole structure of the conjugate rather than the additional local interaction. The redox potential of the probe was independent of the target structure, which is either single- or double stranded. However, the potential is slightly dependent (with a 10-30 mV negative shift on complexation) on the extra sequence in the target, probably because the individual sequence is capable of contacting or interacting with the ferrocenyl group in a slightly different way from each other. This small potential shift itself, however, does not cause any inconvenience on practical applications in detecting the probes by using ECD. These results lead to the conclusion that the redox-active probes are very useful for the microanalysis of nucleic acids due to the stability of the complexes, high detection sensitivity and wide applicability to the target structures (DNA and RNA; single- and double strands) and the sequences.

Pulmonary response to toner upon chronic inhalation exposure in rats

A chronic inhalation study of a test toner was conducted by exposure of groups of F-344 rats for 6 hr/day, 5 days/week for 24 months. The test toner was a special Xerox 9000 type xerographic toner, enriched in respirable-sized particles compared to commercial toner, such that it was about 35% respirable according to the ACGIH criteria. The target test aerosol exposure concentrations were 0, 1.0 (low), 4.0 (medium), and 16.0 (high) mg/m3. Titanium dioxide (5 mg/m3) and crystalline silicon dioxide (1 mg/m3), used as negative and positive controls for fibrogenicity, were also evaluated. Inhalation of the test toner or the control materials showed no signs of overt toxicity. Body weight, clinical chemistry values, food consumption, and organ weights were normal in the toner- and TiO2-exposed groups, except for a 40% increase in lung weight in the toner high-exposure group. All of the changes in the toner-exposed groups were restricted to the lungs or associated lymph nodes. A chronic inflammatory response was evident from the bronchoalveolar lavage parameters for the toner high-exposure group. The incidence of primary lung tumors was comparable among the three toner-exposed groups and the TiO2-exposed, and air-only controls, as well as consistent with historical background levels. A mild to moderate degree of lung fibrosis was observed in 92% of the rats in the toner high-exposure group, and a minimal to mild degree of fibrosis was noted in 22% of the animals in the toner middle-exposure group. The pulmonary changes in the toner high-exposure group were smaller in magnitude than those found in the crystalline silica-exposed group. The comparative fibrogenic potency of TiO2, toner, and SiO2 was estimated to be 1:5:418 using a dosimetric model and assuming a common mechanistic basis. There were no pulmonary changes of any type at the toner low-exposure level, which is most relevant in regard to potential human exposures. The lung alterations in the toner high-exposure group are interpreted in terms of "lung overloading," a generic response of the respiratory system to saturation of its detoxification capacity. The maximum tolerated dose (MTD) criterion was met at the toner high (16 mg/m3)-exposure level.

Potential risk of thermal damage to cervical nerve roots by a high-speed drill

Using the transverse processes of fresh porcine lumbar spines as an experimental model we evaluated the heat generated by a rotating burr of a high-speed drill in cutting the bone. The temperature at the drilled site reached 174 degrees C with a diamond burr and 77 degrees C with a steel burr. With water irrigation at a flow rate of 540 ml/hr an effective reduction in the temperature was achieved whereas irrigation with water at 180 ml/hr was much less effective. There was a significant negative correlation between the thickness of the residual bone and the temperature measured at its undersurface adjacent to the drilling site (p < 0.001). Our data suggest that tissues neighbouring the drilled bone, especially nerve roots, can be damaged by the heat generated from the tip of a high-speed drill. Nerve-root palsy, one of the most common complications of cervical spinal surgery, may be caused by thermal damage to nerve roots arising in this manner.

Pseudovitamin B(12) is the predominant cobamide of an algal health food, spirulina tablets

The vitamin B(12) concentration of an algal health food, spirulina (Spirulina sp.) tablets, was determined by both Lactobacillus leichmannii ATCC 7830 microbiological and intrinsic factor chemiluminescence methods. The values determined with the microbiological method were approximately 6-9-fold greater in the spirulina tablets than the values determined with the chemiluminescence method. Although most of the vitamin B(12) determined with the microbiological method was derived from various vitamin B(12) substitutive compounds and/or inactive vitamin B(12) analogues, the spirulina contained a small amount of vitamin B(12) active in the binding of the intrinsic factor. Two intrinsic factor active vitamin B(12) analogues (major and minor) were purified from the spirulina tablets and partially characterized. The major (83%) and minor (17%) analogues were identified as pseudovitamin B(12) and vitamin B(12), respectively, as judged from data of TLC, reversed-phase HPLC, (1)H NMR spectroscopy, ultraviolet-visible spectroscopy, and biological activity using L. leichmannii as a test organism and the binding of vitamin B(12) to the intrinsic factor.

Electrochemically active DNA probes: detection of target DNA sequences at femtomole level by high-performance liquid chromatography with electrochemical detection

Electrochemically active DNA probes were prepared by linking a ferrocene unit with 5'-aminohexyl-terminated oligonucleotides. The DNA sequences of probes 5a, 5b, and 5c were 5'-T12-3', 5'-T20-3', and 5'-TGCAG TTCCG GTGGC TGATC-3', respectively. Probe 5a could form a complex selectively with a single-strand poly(A) and a double-strand DNA fragment containing an A13 sequence and these complexes could be detected at femtomole levels by an electrochemical detector (ECD) on HPLC. The observed ECD response was proportional to the amount of the complex over the range 20-100 fmol. Probe 5c was capable of detecting femtomole levels of a restriction DNA fragment having oncogene v-myc. Moreover, probe 5b was able to detect picogram levels of mRNA taken from rat brain or yeast total cellular RNA. This proves that the electrochemically active DNA probes are useful in analyzing traces of DNA and RNA carrying the complementary sequence.

Microcystin LR degradation by Pseudomonas aeruginosa alkaline protease

We isolated several species of bacteria from the surface water of a Japanese lake. Of the isolated bacteria, Pseudomonas aeruginosa was the only species which could degrade microcystin LR in vitro. Microcystin LR decreased to 4.5% of the spiked microcystin LR quantity in the P. aeruginosa culture, and was metabolized to (2S, 3S, 8S)-3-amino-2, 6, 8-trimethyl-10-phenyldeca-4E, 6E-dienoic acid (DmADDA). It was possible that P. aeruginosa hydrolysed nucleophilically the peptide bond of microcystin LR. We examined if pyochelin, pyocyanin and alkaline protease produced by P. aeruginosa affected the reduction of microcystin LR. In the result, DmADDA was produced from microcystin LR in the presence of 100 microM H2O2 and 100 microM each of pyochelin, pyocyanin or both. However, the production of DmADDA was slight (2 to 12 mole%). After treatment with P. aeruginosa alkaline protease, DmADDA was produced 75 mole% from microcystin LR. Therefore, we concluded that microcystin was degraded mainly by the action of P. aeruginosa alkaline protease.

Novel genes encoding 2-aminophenol 1,6-dioxygenase from Pseudomonas species AP-3 growing on 2-aminophenol and catalytic properties of the purified enzyme

2-Aminophenol 1,6-dioxygenase was purified from the cell extracts of Pseudomonas sp. AP-3 grown on 2-aminophenol. The product from 2-aminophenol by catalysis of the purified enzyme was identified as 2-aminomuconic 6-semialdehyde by gas chromatographic and mass spectrometric analyses. The molecular mass of the native enzyme was 140 kDa based on gel filtration. It was dissociated into molecular mass subunits of 32 (alpha-subunit) and 40 kDa (beta-subunit) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that the dioxygenase was a heterotetramer of alpha2beta2. The genes coding for the alpha- and beta-subunits of the enzyme were cloned and sequenced. Open reading frames of the genes (amnA and amnB) were 816 and 918 base pairs in length, respectively. The amino acid sequences predicted from the open reading frames of amnA and amnB corresponded to the NH2-terminal amino acid sequences of the alpha-subunit (AmnA) and beta-subunit (AmnB), respectively. The deduced amino acid sequences of AmnB showed identities to some extent with HpaD (25.4%) and HpcB (24.4%) that are homoprotocatechuate 2,3-dioxygenases from Escherichia coli W and C, respectively, belonging to class III in the extradiol dioxygenases. On the other hand, AmnA had identity (23.3%) with only AmnB among the enzymes examined.

Rebamipide protects against activation of neutrophils by Helicobacter pylori

Our objectives were to determine whether rebamipide, a unique antiulcer agent, would inhibit adhesive reactions between neutrophils and endothelial cells as well as the production of active oxygen species from neutrophils elicited by an extract of H. pylori. A water extract of H. pylori that was prepared from biopsy materials obtained from a patient with gastric ulcer increased the surface expression of CD18 on human neutrophils isolated from peripheral blood, the adhesion of neutrophil-endothelial cells, and the production of active oxygen species by neutrophils. Rebamipide, at concentrations of 10(-5) and 10(-6) M, reduced the adherence of neutrophils to endothelial cells as well as the CD18 expression on neutrophils induced by this bacterial extract. Rebamipide also inhibited the production of active oxygen species from neutrophils stimulated by H. pylori extract. These results suggest that rebamipide protects against the gastric mucosal inflammation associated with H. pylori by inhibiting neutrophil function.

Covalent glutathione conjugation to cyanobacterial hepatotoxin microcystin LR by F344 rat cytosolic and microsomal glutathione S-transferases

Most investigators report that microcystins (MCs) bound covalently to SH compounds, such as L-cysteine and reduced glutathione (GSH). However, their studies were based on a high pH condition. In the present study, we investigated the reaction between microcystin LR (MCLR) and GSH in various pH conditions. As a result, we found that no MCLR conjugated with GSH in these conditions, and MCLR mixed with GSH showed different peaks of retention time compared with intact MCLR on the high performance liquid chromatography-mass spectrometry (LC-MS) chromatograms. Furthermore, we found the GSH conjugate of MCLR was detected in the glutathione S-transferase (GST) assay using F344 rat liver cytosol and microsomes. This indicates that the covalent GSH conjugation was caused only by an enzymatic activity. We conclude, therefore, that the reaction is caused by enzymatic action and is not due to the Michael reaction.

Relatively benign clinical course in asymptomatic patients with brugada-type electrocardiogram without family history of sudden death

INTRODUCTION

The incidence of sudden death or ventricular fibrillation (VF) in asymptomatic Brugada syndrome patients with a family history of sudden death is reported to be very high. However, there are few reports on the prognosis of asymptomatic Brugada syndrome patients without a family history of sudden death.

METHODS AND RESULTS

Eleven patients (all male; mean age 40.5 +/- 9.6 years, range 26 to 56) with asymptomatic Brugada-type ECG who had no family history of sudden death were evaluated. The degrees of ST segment elevation and conduction delay on signal-averaged ECG (SAECG) before and after pilsicainide were evaluated in all 11 patients. VF inducibility by ventricular electrical stimulation also was evaluated in 8 of 11 patients. Patients were followed for a period of 9 to 84 months (mean 42.5 +/- 21.6). The J point level was increased (V1: 0.19 +/- 0.09 mV to 0.36 +/- 0.23 mV; V2: 0.31 +/- 0.12 mV to 0.67 +/- 0.35 mV) by pilsicainide. Conduction delay was increased (total QRS: 112.2 +/- 6.3 msec to 131.7 +/- 6.3 msec; under 40 microV: 42.0 +/- 8.5 msec to 52.7 +/- 12.7 msec; last 40 msec: 17.4 +/- 5.9 microV to 10.4 +/- 6.1 microV) on SAECG by pilsicainide. VF was induced in only 1 of 8 patients. None of the patients had syncope or sudden death during a mean follow-up of 42.5 +/- 21.6 months.

CONCLUSION

This study suggests that asymptomatic patients with Brugada-type ECG who have no family history of sudden death have a relatively benign clinical course.

Inhalation of ultrafine carbon particles triggers biphasic pro-inflammatory response in the mouse lung

High levels of particulate matter in ambient air are associated with increased respiratory and cardiovascular health problems. It has been hypothesised that it is the ultrafine particle fraction (diameter <100 nm) that is largely responsible for these effects. To evaluate the associated mechanisms on a molecular level, the current authors applied an expression profiling approach. Healthy mice were exposed to either ultrafine carbon particles (UFCPs; mass concentration 380 microg x m(-3)) or filtered air for 4 and 24 h. Histology of the lungs did not indicate any pathomorphological changes after inhalation. Examination of the bronchoalveolar lavage fluid revealed a small increase in polymorphonuclear cell number (ranging 0.6-1%) after UFCP inhalation, compared with clean air controls, suggesting a minor inflammatory response. However, DNA microarray profile analysis revealed a clearly biphasic response to particle exposure. After 4 h of inhalation, mainly heat shock proteins were induced, whereas after 24 h, different immunomodulatory proteins (osteopontin, galectin-3 and lipocalin-2) were upregulated in alveolar macrophages and septal cells. In conclusion, these data indicate that inhalation of ultrafine carbon particles triggers a biphasic pro-inflammatory process in the lung, involving the activation of macrophages and the upregulation of immunomodulatory proteins.

Feeding dried purple laver (nori) to vitamin B12-deficient rats significantly improves vitamin B12 status

To clarify the bioavailability of vitamin B12 in lyophylized purple laver (nori; Porphyra yezoensis), total vitamin B12 and vitamin B12 analogue contents in the laver were determined, and the effects of feeding the laver to vitamin B12-deficient rats were investigated. The amount of total vitamin B12 in the dried purple laver was estimated to be 54.5 and 58.6 (se 5.3 and 7.5 respectively) microg/100 g dry weight by Lactobacillus bioassay and chemiluminescent assay with hog intrinsic factor respectively. The purple laver contained five types of biologically active vitamin B12 compounds (cyano-, hydroxo-, sulfito-, adenosyl- and methylcobalamin), in which the vitamin B12 coezymes (adenosyl- and methylcobalamin) comprised about 60 % of the total vitamin B12. When 9-week-old vitamin B12-deficient rats, which excreted substantial amounts of methylmalonic acid (71.7(se 20.2) micromol/d) in urine, were fed the diet supplemented with dried purple laver (10 microg/kg diet) for 20 d, urinary methylmalonic acid excretion (as an index of vitamin B12 deficiency) became undetectable and hepatic vitamin B12 (especially adenosylcobalamin) levels were significantly increased. These results indicate that vitamin B12 in dried purple laver is bioavailable to rats.

Fate and toxic effects of inhaled ultrafine cadmium oxide particles in the rat lung

Female Fischer 344 rats were exposed to ultrafine cadmium oxide particles, generated by spark discharging, for 6 h at a concentration of 70 microg Cd/m(3) (1 x 10(6)/cm(3)) (40 nm modal diameter). Lung morphology and quantification of Cd content/concentration by inductively coupled plasma (ICP)-mass spectrometry were performed on days 0, 1, 4, and 7 after exposure. Cd content in the lung on day 0 was 0.53 +/- 0.12 microg/lung, corresponding to 19% of the estimated total inhaled cumulative dose, and the amount remained constant throughout the study. In the liver no significant increase of Cd content was found up to 4 days. A slight but statistically significant increase was observed in the liver on day 7. We found neither exposure-related morphological changes of lungs nor inflammatory responses in lavaged cells. Another group of rats were exposed to a higher concentration of ultrafine CdO particles (550 microg Cd/m(3) for 6 h, 51 nm modal diameter). The rats were sacrificed immediately and 1 day after exposure. The lavage study performed on day 0 showed an increase in the percentage of neutrophils. Multifocal alveolar inflammation was seen histologically on day 0 and day 1. Although the Cd content in the lung was comparable between day 0 and day 1 (3.9 microg/lung), significant elevation of Cd levels in the liver and kidneys was observed on both days. Two of 4 rats examined on day 0 showed elevation of blood cadmium, indicating systemic translocation of a fraction of deposited Cd from the lung in this group. These results and comparison with reported data using fine CdO particles indicate that inhalation of ultrafine CdO particles results in efficient deposition in the rat lung. With regard to the deposition dose, adverse health effects of ultrafine CdO and fine CdO appear to be comparable. Apparent systemic translocation of Cd took place only in animals exposed to a high concentration that induced lung injury.

Artificial Pseudomonas aeruginosa biofilms and confocal laser scanning microscopic analysis

Bacterial biofilms may be formed at various sites, including mucous membranes, teeth, and infectious lesions. To elucidate the structure and the function of biofilms, artificial biofilms of mucoid-type Pseudomonas aeruginosa organisms (strain PT1252) were made by centrifuging the organisms onto the surface of a coverglass and culturing further in broth media supplied continuously (45 ml/h). The biofilm structure at 4, 8, 12, and 24 h was visualized with fluorescent staining (SYTO9, propidium iodide [PI], and/or fluorescein isothiocyanate-concanavalin A [FITC-ConA]) by confocal laser scanning microscopy (CLSM). It was clearly demonstrated that the number of bacteria (10(4)--10(6)/ml) could be estimated by their fluorescence intensity. Sectional analysis of each biofilm layer (1-microm thickness) made it possible to demonstrate the three-dimensional development of biofilms, and revealed that the biofilms were 9 microm in height after 12 h. The live and dead organisms were differentiated by SYTO9 and PI, respectively, in situ in biofilms, and about 13% of the organisms were dead in 12-h-old biofilms. When 12-h-old biofilms were exposed to ciprofloxacin at minimum bactericidal concentration (6.26 microg/ml) for 90 min, all the organisms were killed, but some organisms (11 +/- 1.3%; n = 3) in 24-h-old biofilms with thicker and denser structure were still alive after exposure for 120 min. These results indicate that the CLSM analysis of artificial biofilms was useful for elucidating bacterial functions in biofilms, and may lead to a new quantitative system for estimating the bactericidal efficacy of antibacterial drugs in biofilms.

Oscillation of ADP-ribosyl cyclase activity during the cell cycle and function of cyclic ADP-ribose in a unicellular organism, Euglena gracilis

In Euglena gracilis, the activity of ADP-ribosyl cyclase, which produces cyclic ADP-ribose, oscillated during the cell cycle in a synchronous culture induced by a light-dark cycle, and a marked increase in the activity was observed in the G2 phase. Similarly, the ADP-ribosyl cyclase activity rose extremely immediately before cell division started, when synchronous cell division was induced by adding cobalamin (which is an essential growth factor and participates in DNA synthesis in this organism) to its deficient culture. Further, cADPR in these cells showed a maximum level immediately before cell division started. A dose-dependent Ca2+ release was observed when microsomes were incubated with cADPR.

Anatomic localization of 24- and 96-h particle retention in canine airways

Long-term retention of particles in airways is controversial. However, precise anatomic localization of the particles is not possible in people. In this study the anatomic location of retained particles after shallow bolus inhalation was determined in anesthetized, ventilated beagle dogs. Fifty 30-cm(3) boluses containing monodisperse 2.5-micron polystyrene particles (PSL) were delivered to a shallow lung depth of 81-129 cm(3). At 96 h before euthanasia, red fluorescent PSL were used; at 24 h, green fluorescent PSL and (99m)Tc-labeled PSL were used. Clearance of (99m)Tc-PSL was measured during the next 24 h. Sites of particle retention were determined in systematic, volume-weighted random samples of microwave-fixed lung tissue. Precise particle localization and distribution was analyzed by using gamma counting, conventional fluorescence microscopy, and confocal microscopy. Within 24 h after shallow bolus inhalation, 50-95% of the deposited (99m)Tc-PSL were cleared, but the remaining fraction was cleared slowly in all dogs, similar to previous human results. The three-dimensional deposition patterns showed particles across the entire cross-sectional plane of the lungs at the level of the carina. In these locations, 33 +/- 9.9% of the retained particles were found in small, nonrespiratory airways (0.3- to 1-mm diameter) and 49 +/- 10% of the particles in alveoli; the remaining fraction was found in larger airways. After 96 h, a similar pattern was found. These findings suggest that long-term retention in airways is at the bronchiolar level.

Complete nucleotide sequence and functional analysis of the genes for 2-aminophenol metabolism from Pseudomonas sp. AP-3

A 13.9-kb region, which contained the 2-aminophenol 1,6-dioxygenase genes (amnBA) reported before, was cloned from the 2-aminophenol-assimilating bacterium Pseudomonas sp. AP-3. The complete nucleotide sequence of this region was determined and six genes were found downstream of amnBA. The eight genes together were designated amnBACFEDHG. Each gene was similar to the corresponding gene operating in the meta-cleavage pathway, except for amnB, amnA, and amnD. The four 2-aminophenol-metabolizing enzymes, 2-aminomuconic 6-semialdehyde dehydrogenase, 2-aminomuconate deaminase, 4-oxalocrotonate decarboxylase, and 2-oxopent-4-enoate hydratase, were purified and characterized. NH2-terminal amino acid sequences of each purified enzyme agreed with those deduced from amnC, amnF, amnE, and amnD, respectively. These genes were therefore assigned as the genes encoding these respective proteins. The tight clustering of the amn genes, which were all transcribed in the same direction, raised the possibility that these genes formed a single operon. The organization of the amn genes was entirely different from that of the atd, dmp, and xyl genes reported in the meta-cleavage pathway, although these latter genes clustered similarly.

Characterization of a vitamin B12 compound in the edible purple laver, Porphyra yezoensis

The edible purple laver, Porphyra yezoensis, contained 51.49+/-1.51 microg of vitamin B12 compounds per 100 g dry weight of the laver (mean +/- SEM, n = 4). A vitamin B12 compound was purified from the lyophilized purple laver and partially characterized. The silica gel 60 TLC and reversed-phase HPLC patterns of the purified pink-colored compound were identical to those of authentic vitamin B12, but not to those of vitamin B12 analogues inactive for humans.