[Familial spontaneous pneumothorax]

A case of familial spontaneous pneumothorax was reported. A 52-year-old man was referred to our hospital complaining of exertional dyspnea. He had experienced right spontaneous pneumothorax and cured with tube drainage last year. Five of his 7 brothers and his son too had had spontaneous pneumothorax. Chest X-ray film and computed tomography (CT) scan on admission showed giant bulla of the left lung with compression of normal lungs. Pulmonary function studies revealed obstructive pulmonary disease and mild hypoxemia. Partial resection of the lung with open thoracotomy surgery was performed. Air leaks sealed in 14 days and the patient discharged the hospital with inadequate expansion of the left lung. Three years later the patient experienced right hemicolectomy for colon cancer and died for recurrence 7 years later with adequate expansion of the left lung.

Cloning and characterization of the histidine kinase gene Dic1 from Cochliobolus heterostrophus that confers dicarboximide resistance and osmotic adaptation

A gene for a putative two-component histidine kinase, which is homologous to os-1 from Neurospora crassa, was cloned and sequenced from the plant-pathogenic fungus Cochliobolus heterostrophus. The predicted protein possessed the conserved histidine kinase domain, the response regulator domain, and six tandem repeats of 92-amino-acids at the N-terminal end that are found in histidine kinases from other filamentous fungi. Introduction of the histidine kinase gene complemented the deficiency of the C. heterostrophus dic1 mutant, suggesting that the Dic1 gene product is a histidine kinase. Dic1 mutants are resistant to dicarboximide and phenylpyrrole fungicides, and they are sensitive to osmotic stress. We previously classified dic1 alleles into three types, based on their phenotypes. To explain the phenotypic differences among the dic1 mutant alleles, we cloned and sequenced the mutant dic1 genes and compared their sequences with that of the wild-type strain. Null mutants for Dic1, and mutants with a deletion or point mutation in the N-terminal repeat region, were highly sensitive to osmotic stress and highly resistant to both fungicides. A single amino acid change within the kinase domain or the regulator domain altered the sensitivity to osmotic stress and conferred moderate resistance to the fungicides. These results suggest that this predicted protein, especially its repeat region, has an important function in osmotic adaptation and fungicide resistance.

[Irrigation for the post-pneumonectomy empyema infected by methicillin-resistant Staphylococcus aureus without broncho-pleural fistula; report of a successful case]

It has been known that treatments of post-pneumonectomy empyema are difficult. We report a successful case of irrigation for the post-pneumonectomy. The patient was 68-year-old man with advanced lung cancer. He underwent induction chemoradiotherapy following by pneumonectomy of the right side. A few days later after the chest drain was withdrawn, spike fever appeared. Empyema was suspected, so a 28 Fr diameter double lumen chest drain was intubated again. Turbid effusion was discharged through the drain, in which methicillin-resistant staphylococcus aureus (MRSA) was cultured. Irrigation using a lot of saline and acid electrolyzed water started. A month later, irrigator through the drain was looking clear, however, MRSA was cultured so far. After putting minomycine into the irrigator, MRSA died away. This physical and chemical irrigations were effective.

Iron-Mediated regulation of alkaline proteinase production in Pseudomonas aeruginosa

We analyzed the regulation by iron of alkaline proteinase (AP) production in Pseudomonas aeruginosa. Extracellular AP production was detected from the mid-logarithmic to the stationary phase by an antibody-based assay system, and was strongly repressed by iron in the medium. This repression was shown by Northern hybridization and primer extension to occur at the level of transcription. The primer extension analysis revealed that the start point of transcription of AP gene was the nucleotide position -84 from the start point of translation. Furthermore, we investigated whether this transcriptional repression involved PvdS protein. Using the mutant strain of pvdS, the alternative sigma factor gene revealed that the PvdS protein is required for the full expression of AP, and a previous study showed that expression of pvdS is also repressed by iron. Therefore, we thought that one mechanism of repression of AP production operated through reduction of the PvdS protein level. Purified AP decomposed the transferrin, and released iron from it. Purified AP added to the medium containing transferrin as the only iron source enhanced the growth of P. aeruginosa. Moreover, mutation in the AP gene decreased the growth rate in the medium containing the transferrin as the only iron source. These results clearly indicated that AP expression should occur in a free-iron-deficient environment and emphasized the importance of AP to iron acquisition in the infection site.

Molecular dynamics simulations of Gly-12-->Val mutant of p21(ras): dynamic inhibition mechanism

The mutant p21(ras) protein is a G protein produced by the point-mutated H-ras gene, and this mutant protein has been shown to cause carcinogenesis due to a reduction in its GTPase activity. However, the mechanism underlying this strange phenomenon has still not been elucidated. In our previous study, we have clarified the mechanism of the GTP-->GDP hydrolysis reaction in the wild-type p21(ras) at the atomic level and concluded that GTPase-activating protein plays a significant role in the supply of H2O molecules for the hydrolysis. The structure of the active site in the mutant is the same as that in the wild type. However, by performing molecular dynamic calculations, we found that the structure of the active site of the enzyme substrate complex in the oncogenic mutant p21(ras) continuously changes, and these continuous changes in the active site would make it difficult for the GTP-->GDP hydrolysis reaction to occur in the mutant. These findings can explain the fact that the GTPase activity in the mutant was only 15% of that in the wild type and the fact that GTPase-activating protein has no reaction-activating effect in the mutant. This is a dynamic inhibition mechanism of a vital reaction that can be explained by considering the molecular dynamics.

[Radiofrequency ablation of rabbit liver: correlation between CT findings and pathological findings]

The purpose of this study was to present the time-related imaging findings and correlative pathological findings of irradiated regions in the rabbit liver. RF ablation was carried out on 16 rabbit livers. Irradiated regions were imaged at 3 days, 4 weeks, and 12 weeks. At 3 days, the regions showed a two-zone structure on plain CT and peripheral enhancement on the arterial phase. The regions presented a three-zone structure on pathological study. At 4 weeks, peripheral enhancement had almost disappeared, and a two-zone structure obscured on plain CT. The CT findings reflected pathological changes after RF ablation.

A defect in the cytochrome b large subunit in complex II causes both superoxide anion overproduction and abnormal energy metabolism in Caenorhabditis elegans

A mev-1(kn1) mutant of the nematode Caenorhabditis elegans is defective in the cytochrome b large subunit (Cyt-1/ceSDHC) in complex II of the mitochondrial electron transport chain. We have previously shown that a mutation in mev-1 causes shortened life span and rapid accumulation of aging markers such as fluorescent materials and protein carbonyls in an oxygen-dependent fashion. However, it remains unclear as to whether this hypersensitivity is caused by direct toxicity of the exogenous oxygen or by the damage of endogenous reactive oxygen species derived from mitochondria. Here we report important biochemical changes in mev-1 animals that serve to explain their abnormalities under normoxic conditions: (i) an overproduction of superoxide anion from mitochondria; and (ii) a reciprocal reduction in glutathione content even under atmospheric oxygen. In addition, unlike wild type, the levels of superoxide anion production from mev-1 mitochondria were significantly elevated under hyperoxia. Under normal circumstances, it is well known that superoxide anion is produced at complexes I and III in the electron transport system. Our data suggest that the mev-1(kn1) mutation increases superoxide anion production at complex II itself rather than at complexes I and III. The mev-1 mutant also had a lactate level 2-fold higher than wild type, indicative of lactic acidosis, a hallmark of human mitochondrial diseases. These data indicate that Cyt-1/ceSDHC plays an important role not only in energy metabolism but also in superoxide anion production that is critically involved in sensitivity to atmospheric oxygen.

Simultaneous expression of guinea pig UDP-glucuronosyltransferase 2B21 and 2B22 in COS-7 cells enhances UDP-glucuronosyltransferase 2B21-catalyzed morphine-6-glucuronide formation

Although UDP-glucuronosyltransferases (UGTs) act as an important detoxification system for many endogenous and exogenous compounds, they are also involved in the metabolic activation of morphine to form morphine-6-glucuronide (M-6-G). The cDNAs encoding guinea pig liver UGT2B21 and UGT2B22, which are intimately involved in M-6-G formation, have been cloned and characterized. Although some evidence suggests that UGTs may function as oligomers, it is not known whether hetero-oligomer formation leads to differences in substrate specificity. In this work, evidence for a functional hetero-oligomer between UGT2B21 and UGT2B22 is provided by studies on the glucuronidation of morphine in transfected COS-7 cells. Cells transfected with UGT2B21 cDNA catalyzed mainly morphine-3-glucuronide formation although M-6-G was also formed to some extent. In contrast, cells transfected with UGT2B22 cDNA did not show any significant activity toward morphine. When UGT2B21 and UGT2B22 were expressed simultaneously in different ratios in COS-7 cells, extensive M-6-G formation was observed. This stimulation of M-6-G formation was not observed, however, when microsomes containing UGT2B21were mixed with those containing UGT2B22 in the presence of detergent. Furthermore, this effect was not very marked when human UGT1A1 and UGT2B21 were coexpressed in COS-7 cells. This is the first report suggesting that UGT hetero-oligomer formation leads to altered substrate specificity.

Hepatocellular carcinoma after radiofrequency ablation therapy: dynamic CT evaluation of treatment

The aim of this study is to analyze the dynamic CT findings after radiofrequency (RF) ablation for hypervascular hepatocellular carcinoma (HCC). RF ablation was used for 22 tumors in 20 patients. Peripheral enhancement was noted in 89% of regions within 1 month in the arterial phase. In 1-3 months, peripheral enhancement remained at 56% and was reduced to 22% by 3-6 months. It is difficult to determine the therapeutic result within 3 months due to continued peripheral enhancement in the arterial phase.

Identification and characterization of Tn4656, a novel class II transposon carrying a set of toluene-degrading genes from TOL plasmid pWW53

It has been reported that the toluene-degrading (xyl) genes from Pseudomonas putida plasmid pWW53 are able to translocate to broad-host-range drug resistance plasmid RP4, and pWW53-4 is one of the smallest RP4 derivatives (H. Keil, S. Keil, R. W. Pickup, and P. A. Williams, J. Bacteriol. 164:887-895, 1985). Our investigation of pWW53-4 in this study demonstrated that such a translocated region that is 39 kb long is a transposon. This mobile element, Tn4656, was classified as a class II transposon since its transposition occurred by a two-step process: transposase (TnpA)-mediated formation of the cointegrate and resolvase (TnpR)-mediated site-specific resolution of the cointegrate at the two copies of the res site. The Tn4656 TnpA and TnpR functions encoded in the rightmost 4-kb region were found to be exchangeable with those specified by other Tn1721-related class II transposons, including another toluene transposon, Tn4653. Sequence analysis of the transposition-related genes and sites of Tn4656 also supported the hypothesis that this transposon is closely related to the Tn1721-related transposons. The lower transposition frequency of Tn4656 has been suggested to be due to the unique nucleotide sequence of one of the terminal 39-bp inverted repeats.

Theoretical studies of the ATP hydrolysis mechanism of myosin

The ATP hydrolysis mechanism of myosin was studied using quantum chemical (QM) and molecular dynamics calculations. The initial model compound for QM calculations was constructed on the basis of the energy-minimized structure of the myosin(S1dc)-ATP complex, which was determined by molecular mechanics calculations. The result of QM calculations suggested that the ATP hydrolysis mechanism of myosin consists of a single elementary reaction in which a water molecule nucleophilically attacked gamma-phosphorus of ATP. In addition, we performed molecular dynamics simulations of the initial and final states of the ATP hydrolysis reaction, that is, the myosin-ATP and myosin-ADP.Pi complexes. These calculations revealed roles of several amino acid residues (Lys185, Thr186, Ser237, Arg238, and Glu459) in the ATPase pocket. Lys185 maintains the conformation of beta- and gamma-phosphate groups of ATP by forming the hydrogen bonds. Thr186 and Ser237 are coordinated to a Mg(2+) ion, which interacts with the phosphates of ATP and therefore contributes to the stabilization of the ATP structure. Arg238 and Glu459, which consisted of the gate of the ATPase pocket, retain the water molecule acting on the hydrolysis at the appropriate position for initiating the hydrolysis.

Estrogen replacement therapy in postmenopausal women augments reactive hyperemia in the forearm by reducing angiotensin converting enzyme activity

The precise mechanism of the vasoprotective effect of estrogen replacement therapy in postmenopausal women is not fully understood. The present study sought to determine the role of nitric oxide (NO) and angiotensin-converting enzyme (ACE) in the vasodilator response of the forearm vessels induced by estrogen administration to postmenopausal women. Subjects were divided into two groups. One group received conjugated equine estrogen (0.625 mg daily) orally for 3 months (n=26), while the other received no treatment (control group, n=10). Forearm blood flow was measured by strain-gauge plethysmography. The concentrations of nitrite/nitrate (metabolites of NO), ACE activity, and lipid parameters were measured. Basal forearm blood flow, body weight, blood pressure, and heart rate were similar at baseline in both groups. After 3 months of estrogen administration, the maximal forearm blood flow response during reactive hyperemia and the serum level of nitrite/nitrate each showed a significant increase over baseline values: from 23.6+/-2.0 to 36.5+/-3.1 ml/min per 100 ml tissue (P<0.01), and from 24.8+/-2.3 to 38.6+/-3.6 micromol/l (P<0.01), respectively. Plasma levels of ACE activity were significantly reduced from baseline after 3 months of estrogen treatment (from 12.2+/-0.6 to 10.9+/-0.6 IU/l, P<0.01). No changes were seen in controls. The change in forearm blood flow after sublingual nitroglycerin was similar at baseline versus after 3 months of estrogen administration. The increase in the serum level of nitrite/nitrate after 3 months of estrogen therapy showed a significant inverse correlation (r=0.52, P<0.01) with the reduction in the plasma level of ACE activity. There was no significant correlation between the increase in serum nitrite/nitrate and any change in serum lipids, blood pressure, or other parameters. The administration of oral estrogen to postmenopausal women for 3 months increased the NO-mediated forearm endothelium-dependent vasodilatation. This was likely due, at least in part, to ACE inhibition. The latter may be one mechanism by which ERT provides its well-known cardiovascular benefit.

Biosynthetic study of amphidinolide B

The biosynthetic origins of amphidinoide B (1) were investigated on the basis of 13C-NMR data of 13C-enriched samples obtained by feeding experiments with [1-(13)C], [2-(13)C], and [1,2-(13)C2] sodium acetates in cultures of a dinoflagellate Amphidinium sp. These incorporation patterns suggested that 1 was generated from three successive polyketide chains, an isolated C1 unit from C-2 of acetates, six branched C1 units from C-2 of acetates, and an "m-m" and an "m-m-m" unit derived only from C-2 of acetates. The labeling patterns of amphidinolide B (1) were different from those of amphidinolide H (2), a 26-membered macrolide closely related to 1.

Ci-opsin1, a vertebrate-type opsin gene, expressed in the larval ocellus of the ascidian Ciona intestinalis

A novel gene encoding visual pigment, Ci-opsin1, was identified in a primitive chordate, the ascidian, Ciona intestinalis. Molecular phylogenetic analysis and the exon-intron organization suggest that Ci-opsin1 is closely related to the retinal and pineal opsins of vertebrates. During embryogenesis, Ci-opsin1 transcripts were first detected in part of the brain of mid tailbud embryos; its expression was confined to photoreceptor cells of the ocellus (eye spot) in the larval brain as development proceeded. These results suggest a common descent of the ascidian ocellus and the vertebrate eyes. The ocellus of ascidian larvae may represent an ancestral state of the vertebrate eye.

Mechanisms underlying extracellular ATP-evoked interleukin-6 release in mouse microglial cell line, MG-5

Microglia play various important roles in the CNS via the synthesis of cytokines. The ATP-evoked production of interleukin-6 (IL-6) and its intracellular signals were examined using a mouse microglial cell line, MG-5. ATP, but not its metabolites, produced IL-6 in a concentration-dependent manner. Although ATP activated two mitogen-activated protein kinases, i.e. p38 and extracellular signal-regulated protein kinase, only p38 was involved in the IL-6 induction. However, the activation of p38 was not sufficient for the IL-6 induction because 2'- and 3'-O-(4-benzoylbenzoyl) ATP, an agonist to P2X7 receptors, failed to produce IL-6 despite the fact that it activated p38. Unlike in other cytokines in microglial cells, P2Y rather than P2X7 receptors seem to have a major role in the IL-6 production by the cells. The ATP-evoked IL-6 production was attenuated by Gö6976, an inhibitor of Ca(2+)-dependent protein kinase C (PKC). The P2Y receptor responsible for these responses was insensitive to pertussis toxin (PTX) and was linked to phospholipase C. Taken together, ATP acting on PTX-insensitive P2Y receptors activates p38 and Ca(2+)-dependent PKC, thereby resulting in the mRNA expression and release of IL-6 in MG-5. This is a novel pathway for the induction of cytokines in microglia.

Intracellular Ca(2+) changes induced by in vitro ischemia in rat retinal slices

The effect of ischemia on intracellular Ca(2+)concentration [[Ca(2+)](i)] in retinal slices was investigated. [Ca(2+)](i)in each layer of the retina was determined from fluorescence images in rat retinal slices loaded with fura2-AM. Ischemic like conditions were imposed on the retinal slice in vitro by perfusion with an oxygen/glucose deprived solution. All measurements were taken at 25 degrees C except when temperature dependence was examined. In response to 100 m M K(+)or 0.2 m M glutamate under normoxic conditions, the [Ca(2+)](i)increase was higher in the inner retinal layers. Fifteen min ischemia evoked an increase in Ca(2+)levels in all layers of the retina, and the rates of increase were especially high in the outer/inner segment layer and the outer nuclear layer. Ischemia in the absence of extracellular Ca(2+)also induced a Ca(2+)rise, but at lower rates than with standard ischemia. Intermittent ischemia, composed of three 15 min bursts of ischemia at 10 min intervals, promoted the Ca(2+)rise. There was a more marked rise in [Ca(2+)](i)when the temperature was increased to 29 or 33 degrees C. Thus, in the rat retinal slice, in vitro ischemia evoked a more marked Ca(2+)rise in the outer retina, which was in contrast to the Ca(2+)responses to glutamate or high K(+). The rates of increase in [Ca(2+)](i)with ischemia were larger at higher temperatures, and intermittent ischemia also promoted the Ca(2+)rise. These increases appear to be derived from predominant influx of extracellular Ca(2+)rather than release of intracellular Ca(2+)stores.

A spectrally silent transformation in the photolysis of octopus rhodopsin: a protein conformational change without any accompanying change of the chromophore's absorption

A spectrally silent transformation in the photolysis of octopus rhodopsin was detected by the time-resolved transient grating method. Our results showed that at least two photointermediates, which share the same chromophore absorption spectrum, exist after the final absorption changes. Previously, mesorhodopsin was thought to decay to the final photoproduct, acid metarhodopsin with a lifetime of 38 micros at 15 degrees C, but the present results show that there is at least one intermediate species (called transient acid metarhodopsin) with a lifetime of 180 micros at 15 degrees C, before forming acid metarhodopsin. This indicates that the parts of the protein distant from the chromophore are still changing even after the changes in microenvironment around the chromophore are over. From the signal intensity detected by the transient grating method, the volume change of the spectrally silent transformation was found to be DeltaV = 13 ml/mol. The activation energy of the spectrally silent transformation is much lower than those of other transformations of octopus rhodopsin. Since stable acid metarhodopsin has not been shown to activate the G protein, this transient acid metarhodopsin may be responsible for G protein activation.

Monooxygenation mechanism by cytochrome p-450

The substrate oxygenation mechanism by an ultimate species in monooxygenation by cytochrome P-450 (compound I) was investigated by the density functional theory method. An initial model compound was constructed from a structure obtained by 300-ps molecular dynamics simulation of compound I-formed P-450cam under physiologic conditions, and it consisted of porphine for protoporphyrin IX, S(-)-CH(3) for the side chain of Cys357 of the fifth ligand of heme, a methane molecule for the substrate, a heme iron, and an oxygen atom of the sixth ligand of heme. The results of the calculation revealed that the substrate oxygenation mechanism had four elementary processes, i.e., (1) formation of [FeOH](3+) and a substrate radical by hydrogen atom abstraction from the substrate caused by [FeO](3+), (2) rotation of the OH group of the sixth ligand of [FeOH](3+) produced by process 1, (3) substrate radical binding with the [FeOH](3+), and (4) elimination of the oxygenated substrate formed at the sixth ligand binding site. The rate-determining step is process 1, hydrogen atom abstraction from the substrate, and the activation energy was determined to be about 15 kcal/mol. For this reason, it is thought that this reaction occurs in vivo.

[Molecular science of the living organism: the case of G-proteins]

The concept of Molecular Science of the Living Organism was described, where the living state is explained as the purposive flows of the quantum mechanically controlled chemical reaction systems which support the homeostasis of the living organism. In the 21st century, the post genomic sequence era, the concept may be a self-evident truth. Molecular Science of the Living Organism was presented in the case of G-proteins: i.e., the atomically controlled mechanism of 1. the carcinogenesis which originates from the point mutation of ras p21, 2. the activation of a receptor protein at the cell membrane, especially in the case of bacteriorhodopsin, 3. the activation of an inactive G-protein by the activated receptor protein.