Identification and characterization of genes encoding carbazole 1,9a-dioxygenase in Pseudomonas sp. strain CA10

Nucleotide sequence analysis of the flanking regions of the carBC genes of Pseudomonas sp. strain CA10 revealed that there were two open reading frames (ORFs) ORF4 and ORF5, in the upstream region of carBC. Similarly, three ORFs, ORF6 to ORF8, were found in the downstream region of carBC. The deduced amino acid sequences of ORF6 and ORF8 showed homologies with ferredoxin and ferredoxin reductase components of bacterial multicomponent dioxygenase systems, respectively. ORF4 and ORF5 had the same sequence and were tandemly linked. Their deduced amino acid sequences showed about 30% homology with large (alpha) subunits of other terminal oxygenase components. Functional analysis using resting cells harboring the deleted plasmids revealed that the products of ORF4 and -5, ORF6, and ORF8 were terminal dioxygenase, ferredoxin, and ferredoxin reductase, respectively, of carbazole 1,9a-dioxygenase (CARDO), which attacks the angular position adjacent to the nitrogen atom of carbazole, and that the product of ORF7 is not indispensable for CARDO activity. Based on the results, ORF4, ORF5, ORF6, and ORF8 were designated carAa, carAa, carAc, and carAd, respectively. The products of carAa, carAd, and ORF7 were shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be polypeptides with molecular masses of 43, 36, and 11 kDa, respectively. However, the product of carAc was not detected in Escherichia coli. CARDO has the ability to oxidize a wide variety of polyaromatic compounds, including dibenzo-p-dioxin, dibenzofuran, biphenyl, and polycyclic aromatic hydrocarbons such as naphthalene and phenanthrene. Since 2,2',3-trihydroxydiphenyl ether and 2,2',3-trihydroxybiphenyl were identified as metabolites of dibenzo-p-dioxin and dibenzofuran, respectively, it was considered that CARDO attacked at the angular position adjacent to the oxygen atom of dibenzo-p-dioxin and dibenzofuran as in the case with carbazole.

Cloning of genes involved in carbazole degradation of Pseudomonas sp. strain CA10: nucleotide sequences of genes and characterization of meta-cleavage enzymes and hydrolase

The DNA fragment encoding meta-cleavage enzymes and the meta-cleavage compound hydrolase, involved in carbazole degradation, was cloned from the carbazole-utilizing bacterium Pseudomonas sp. strain CA10. DNA sequence analysis of this 2.6-kb SmaI-SphI fragment revealed that there were three open reading frames (ORF1, ORF2, and ORF3, in this gene order). ORF1 and ORF2 were indispensable for meta-cleavage activity for 2'-aminobiphenyl-2,3-diol and its easily available analog, 2,3-dihydroxybiphenyl, and were designated carBa and carBb, respectively. The alignment of CarBb with other meta-cleavage enzymes indicated that CarBb may have a non-heme iron cofactor coordinating site. On the basis of the phylogenetic tree, CarBb was classified as a member of the protocatechuate 4,5-dioxygenase family. This unique extradiol dioxygenase, CarB, had significantly higher affinity and about 20-times-higher meta-cleavage activity for 2,3-dihydroxybiphenyl than for catechol derivatives. The putative polypeptide encoded by ORF3 was homologous with meta-cleavage compound hydrolases in other bacteria, and ORF3 was designated carC. The hydrolase activity of CarC for 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid, the meta-cleavage compound of 2,3-dihydroxybiphenyl, was 40 times higher than that for 2-hydroxy-6-oxohepta-2,4-dienoic acid, the meta-cleavage compound of 3-methylcatechol. Alignment analysis and the phylogenetic tree indicate that CarC has greatest homologies with hydrolases involved in the monoaromatic compound degradation pathway. These results suggest the possibility that CarC is a novel type of hydrolase.

Triggers of hair cell regeneration in the avian inner ear

We performed an in vitro study in order to determine possible triggers of hair cell regeneration in the chick basilar papilla following degeneration. We compared the response of sensory epithelium damaged by collagenase treatment with that damaged by acoustic trauma. The former exhibited no proliferative activity, but the latter did. The basilar papillae damaged by acoustic trauma could have proliferating activity in medium containing fetal bovine serum (FBS) or epidermal growth factor (EGF) but not in the medium without FBS or EGF. These findings indicate that regeneration of basilar papillae depends on the manner of cell death and that FBS or EGF is required for regeneration.

Temporal bone pathology of a patient with cochlear implant

A 66-year-old man with profound total deafness received a 22-channel cochlear implant. After surgery, his hearing improved and the postoperative course was uneventful except transient vertigo. The patient died of lung cancer after 2.5 years. Twelve hours after death, the temporal bone was harvested for histological and electron microscopic examination. The mastoid air cells were preserved, although a few mucosal folds were present. The Dacron mesh tie had largely been absorbed, but part remained embedded in fibrous tissue. No inflammation was noted in the tympanic cavity or the round window through which the electrodes were inserted. In the cochlea, the scala tympani was filled with fibrous tissue at the site of electrode insertion. The scala media had collapsed, while the organ of Corti and stria vascularis showed degeneration. Osseous spiral bundles and spiral ganglion cells were noted, though reduced in number.

Nitric oxide synthase and contractile protein in the rat cochlear lateral wall: possible role of nitric oxide in regulation of strial blood flow

The present study demonstrated by histochemical and immunohistochemical methods that NADPH diaphorase reactivity, endothelial nitric oxide synthase (eNOS)-like immunoreactivity, and tropomyosin-like immunoreactivity, were located within the rat cochlear lateral wall. Both NADPH diaphorase reactivity and eNOS-like immunoreactivity were found mainly in the endothelium of the strial capillaries (ESC) and that of the vessels of the spiral ligament (ESL). These reaction products appeared to be somewhat more common in the ESC than in the ESL. On the other hand, tropomyosin-like immunoreactivity was localized in tissues outside the endothelium and its intensity was greater in the ESL than in the ESC. These findings suggest that nitric oxide (NO) produced by eNOS may play a role in regulating the blood flow of the cochlear lateral wall. In addition, NADPH diaphorase reactivity, eNOS-like immunoreactivity, and tropomyosin-like immunoreactivity showed different patterns of distribution between ESC and ESL. This suggests that in these two sites blood circulation is controlled by NO through two different mechanisms that are suitable for regulating strial blood flow.

Identification of stylar RNases associated with gametophytic self-incompatibility in almond (Prunus dulcis)

Stylar proteins of 13 almond (Prunus dulcis) cultivars with known S-genotypes were surveyed by IEF and 2D-PAGE combined with immunoblot and N-terminal amino acid sequence analyses to identify S-RNases associated with gametophytic self-incompatibility (SI) in this plant species. RNase activities corresponding to Sa and Sb, two of the four S-alleles tested, were identified by IEF and RNase activity staining. The Sa-RNase band reacted with the anti-S4-serum prepared from Japanese pear (Pyrus serotina); no reaction with the antiserum was observed with the Sb-RNase band. When the Sa-RNase band was excised from an IEF gel stained for RNase activity, subjected to SDS-PAGE, and detected by immunoblotting, it appeared that this band consisted of a single protein that reacted with the anti-S4-serum with M(r) of about 28 kDa. With 2D-PAGE and silver staining of the stylar extracts, all four S-proteins could be successfully distinguished from each other in the highly basic zone of the gel. Although Sb-, Sc-, and Sd-proteins had roughly the same M(r) of about 30 kDa, the Sc-protein seemed to be slightly smaller than the Sb-protein and slightly larger than the Sd-protein. In 2D-PAGE profiles as well, the Sa-protein had M(r) of about 28 kDa, apparently smaller than the other three proteins. A bud sport, in which one of the two S-alleles of the original cultivar is impaired, was visualized as a loss of Sc-protein, which is consistent with the previous pollination study. All four S-proteins reacted with the anti-S4-serum, probably because of the differing conformations of these S-proteins in the IEF and 2D-PAGE gels. The Sa-protein in 2D-PAGE appeared to be identical to Sa-RNase in IEF; both had the same M(r) and were reactive with the anti-S4-serum. N-terminal amino acid sequence analysis of the four S-proteins revealed that they were highly homologous to each other and similar to the S-RNases of Malus, Pyrus, Scrophulariaceae, and Solanaceae. Taken together, RNases in the style are strongly suggested to be associated with the gametophytic SI of almond. This is the first report identifying and characterizing S-RNase in almond.

Biosynthesis of GA73 Methyl Ester in Lygodium Ferns

Biosynthesis of GA73 methyl ester (GA73-Me), the principal antheridiogen in Lygodium ferns, was investigated. From the methanol extract of prothallia of Lygodium circinnatum, GA25, GA73, GA73-Me, GA88-Me, and a few unknown GA73 derivatives were detected by GC-MS. Because the presence of GA25 suggests that GA24, a direct precursor of GA25, could also be present in L. circinnatum prothallia, we used feeding experiments to investigate the possibility that GA24 is a precursor of GA73-Me. In L. circinnatum prothallia, [2H2]GA24 was converted into [2H2]GA73-Me and a trace amount of [2H2]GA9-Me, whereas [2H3]GA9 was converted into [2H3]GA9-Me and [2H3]monohydroxy-GA9-Me. Because GA73-Me, GA9-Me, and their monohydroxy derivatives had been identified by GC-MS from the culture medium of L. circinnatum prothallia, our results suggest that GA73-Me is biosynthesized from GA24 via GA73, and that neither GA9 nor GA9-Me is a precursor of GA73-Me. Though the possibility had been suggested that GA73-Me is biosynthesized from 9,15-cyclo-GA9 (GA103), [2H2]GA103 was not converted into [2H2]GA73-Me.

Subunit Ya-specific glutathione peroxidase activity toward cholesterol 7-hydroperoxides of glutathione S-transferases in cytosols from rat liver and skin

Dermal 7alpha- and 7beta-hydroperoxycholest-5-en-3beta-ols (cholesterol 7alpha- and 7beta-hydroperoxides), regarded as good aging markers in the rat (Ozawa, N., Yamazaki, S., Chiba, K., Aoyama, H., Tomisawa, H., Tateishi, M., and Watabe, T. (1991) Biochem. Biophys. Res. Commun. 178, 242-247), were reduced in the presence of glutathione (GSH) with concomitant formation of GSSG by cytosol from rat liver in which no detectable level of the hydroperoxides had been demonstrated to occur. The GSH peroxidase (GSH Px) activity toward the toxic steroid hydroperoxides was exerted to almost the same extent by both Alpha-class GSH S-transferases (GSTs), Ya-Ya and Ya-Yc, and by selenium-containing GSH Px (Se-GSH Px) in rat liver cytosol. None of three Mu-class GSTs, Yb1-Yb1, Yb1-Yb2, and Yb2-Yb2, and a Theta-class GST, Yrs-Yrs, from rat liver and a Pi-class GST, Yp-Yp, from rat kidney showed any appreciable GSH Px activity toward the hydroperoxides. The subunit Ya-bearing GSTs and Se-GSH Px purified from rat liver cytosol showed marked differences in apparent specific activity toward the cholesterol hydroperoxides (GSTs Ya-Ya > Ya-Yc >> Se-GSH Px). However, a kinetic study indicated that Se-GSH Px had a higher affinity for steroid hydroperoxides than did the GSTs, so that Se-GSH Px could catalyze the reduction of lower concentrations of cholesterol 7-hydroperoxides with approximately equal Vmax/Km values to those by the GSTs. Rat skin had no GST bearing the subunit Ya but contained only a very low concentration of Se-GSH Px, possibly resulting in the accumulation of cholesterol 7-hydroperoxides in the skin but not in the liver. From rat skin cytosol, GSTs Yc-Yc, Yb1-Yb1, Yb1-Yb2, Yb2-Yb2, and Yp-Yp were isolated, purified to homogeneity, and identified with the corresponding GSTs from liver and kidney. The GSTs accounted for 0.23% of total skin cytosolic protein, and the most abundant isoform of skin GSTs was Yb2-Yb2, followed by Yc-Yc, Yp-Yp, Yb1-Yb1, and Yb1-Yb2 in decreasing order.

Cell death caused by the acute effects of aminoglycoside and zinc in the ampullary cristae of guinea pigs

We reported that apoptosis occurred in the guinea pig vestibular hair cells after chronic aminoglycoside treatments. In the present study, we used in situ nick-end labeling to determine whether apoptosis was also induced by the acute effects of aminoglycosides in guinea pig ampullar cristae. In addition, we evaluated the effect of zinc supplements upon these ototoxic treatments. After a local application of streptomycin directly to the round window, we found labeled bodies in the vestibular hair cells. The zinc supplement increased the number of labeled bodies resulting in severe hair cell loss. These findings indicate that the acute effects of aminoglycosides also induce apoptosis of the vestibular hair cells, and that zinc enhances aminoglycoside ototoxicity. Consequently, we propose that an interaction with ion channels may play a key mechanism in the processes of apoptosis affecting the vestibular hair cells.

Induction of free radicals in the cochlea by an aminoglycoside antibiotic

Free radicals are known to cause damage to biological tissues. We used histochemical methods to examine the emergence of free radicals in kanamycin (KM)-treated guinea pig cochlea. As a preliminary in vitro study, the emergence of free radicals was observed in guinea pig cochlea incubated with KM. In an in vivo study, KM was placed on the guinea pig round window membrane and the emergence of free radicals was observed over time. The emergence of free radicals was observed along the luminal membrane and hair bundles of outer hair cells. The appearance and disappearance of free radicals in the cochlea coincided with the transport of KM into the inner ear. These findings suggest that the emergence of free radicals could be attributed to the administration of KM.

Gentamicin ototoxicity induced apoptosis of the vestibular hair cells of guinea pigs

To clarify mechanisms of inner ear cell death induced by aminoglycosides, we used an in situ nick-end labelling method to examine guinea pig vestibular epithelia after chronic systemic treatments with gentamicin to produce apoptosis. Such changes occurred in damaged hair cells, suggesting that this process may be crucial for subsequent repair and cell regeneration.

Asialo GM1-positive cells in mouse cochlea

The presence of ganglio-N-tetraosylceramide (asialo GM1)-positive cells in mouse cochlea was tested for using an immunohistochemical method with an anti-asialo GM1 antibody which reacts with natural killer cells and macrophages in mouse. Only a few asialo GM1-positive cells were present on the surface of the scala tympani of the basal turn near the collecting venules. Transmission electron microscopic study showed the internal structure of these cells to be that of macrophages. These findings suggest that asialo GM1-positive cells function as resident type macrophages against invasion by pathogens of the mouse cochlea.

Analysis of cumene (isopropylbenzene) degradation genes from Pseudomonas fluorescens IP01

We obtained the DNA fragments encoding 2-hydroxy-6-oxo-7-methylocta-2,4-dienoic acid (HOMODA) hydrolase in the cumene (isopropylbenzene) degrader Pseudomonas fluorescens strain IP01 via PCR using two synthesized oligonucleotides corresponding to the conserved regions within known meta-cleavage compound hydrolases. Following colony hybridization using the amplified DNA as a probe, a 4.5-kb HindIII fragment was isolated from P. fluorescens IP01. After determining the nucleotide sequence of this fragment, three open reading frames (ORF11 [cumH], ORF12 [cumD], and ORF13) were identified. The deduced amino acid sequence of ORF12 showed homology with meta-cleavage compound hydrolases encoded by the tod, dmp, xyl, and bph operons. Although the product of ORF12 was found to exhibit HOMODA and 2-hydroxy-6-oxohepta-2,4-dienoic acid (HOHDA) hydrolase activities, it did not exhibit 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) hydrolase activity. The deduced amino acid sequence of ORF11 showed 40.4% homology with the sequence of todX in Pseudomonas putida F1 (Y. Wang, M. Ralings, D. T. Gibson, D. Labbé, H. Bergeron, R. Brousseau, and P. C. K. Lau, Mol. Gen. Genet. 246:570-579, 1995). The nucleotide sequence of ORF13 and its flanking region showed strong homology (91.0%) with IS52 from Pseudomonas savastanoi (Y. Yamada, P.-D. Lee, and T. Kosuge, Proc. Natl. Acad. Sci. USA 83:8263-8267, 1982). By characterization of cumH and cumD, the entire cum gene cluster from the cumene-degrader P. fluorescens IP01 (cumA1A2A3A4BCEGFHD) has been identified.

[Chemotherapy for small-cell lung cancer]

Here we review the current treatments for small-cell lung cancer. Cisplatin and etoposide, combined with concurrent or alternating thoracic irradiation, have been considered to be the standard therapy for patients with limited disease. Dose-intensive weekly chemotherapy and high-dose chemotherapy with autologous stem cell transplantation have failed to increase survival in patients with extensive disease. Promising new drugs such as irinotecan and taxol may improve survival in patients with extensive disease.

Sphingosine inhibition of NADPH oxidase activation in a cell-free system

The effects of sphingoid bases, sphingosine and dihydrosphingosine, which are protein kinase C (PKC) inhibitors, on NADPH oxidase were examined in a cell-free system. The bases inhibited cell-free activation of NADPH oxidase by arachidonic acid at lower concentration than N-acetylsphingosine. Thus, positive charge in the molecules may play a critical role in inhibition of the oxidase. Sphingosine did not change the Km value for NADPH, but shifted the optimum concentration of arachidonic acid for activation of the oxidase. Moreover, sphingosine suppressed the translocation of p47-phox, one of the cytosolic components of the oxidase, to the membrane fraction, suggesting that the base inhibits the assembly of the components.

Molecular cloning and characterization of a cDNA encoding the gibberellin biosynthetic enzyme ent-kaurene synthase B from pumpkin (Cucurbita maxima L.)

The first committed step in the formation of diterpenoids leading to gibberellin (GA) biosynthesis is the conversion of geranylgeranyl diphosphate (GGDP) to ent-kaurene. ent-Kaurene synthase A (KSA) catalyzes the conversion of GGDP to copalyl diphosphate (CDP), which is subsequently converted to ent-kaurene by ent-kaurene synthase B (KSB). A full-length KSB cDNA was isolated from developing cotyledons in immature seeds of pumpkin (Cucurbita maxima L.). Degenerate oligonucleotide primers were designed from the amino acid sequences obtained from the purified protein to amplify a cDNA fragment, which was used for library screening. The isolated full-length cDNA was expressed in Escherichia coli as a fusion protein, which demonstrated the KSB activity to cyclize [3H]CDP to [3H]ent-kaurene. The KSB transcript was most abundant in growing tissues, but was detected in every organ in pumpkin seedlings. The deduced amino acid sequence shares significant homology with other terpene cyclases, including the conserved DDXXD motif, a putative divalent metal ion-diphosphate complex binding site. A putative transit peptide sequence that may target the translated product into the plastids is present in the N-terminal region.

cDNA cloning and characterization of a gibberellin-responsive gene in hypocotyls of Cucumis sativus L

A cDNA clone corresponding to a gibberellin-responsive gene (CRG16) was isolated from cucumber hypocotyls. CRG16 was deduced to encode an extremely hydrophobic protein of 65 amino acids. The deduced sequence exhibited no significant homology to other proteins. Levels of CRG16 mRNA reflected the gibberellin-induced elongation of cucumber hypocotyls.

The use of epoxy patch grafts for the repair of experimentally-created diaphragmatic defects in dogs

Canine pericardium which had been treated with polyepoxy compounds (Denacol EX-313) was used as a patch graft for the correction of experimentally-created diaphragmatic defects in five dogs belonging to the same litter. Clinical, macroscopic and histological examinations were conducted every month up to five months after suturing of the patch graft. Clinical examination of the patch graft showed no apparent abnormalities. Macroscopic examination conducted during autopsy showed that the patch graft maintained adequate elasticity for five months after suturing, the surface of the patch graft was covered with a thin membrane and neovascularization was observed. Histological examination showed that the surface of the patch graft was covered with a thin membrane. Inflammatory tissue reactions were observed at one month, but gradually decreased from the second month onwards. In addition, the patch graft had excellent tissue affinity.

Identification of Antheridiogens in Lygodium circinnatum and Lygodium flexuosum

Antheridiogens in two species of Schizaeaceous ferns, Lygodium circinnatum and Lygodium flexuosum, were analyzed by gas chromatography-mass spectrometry. In L. circinnatum, gibberellin A73 (GA73) methyl ester (GA73-Me), which had originally been identified in L. japonicum, was identified as a principal antheridiogen, and the methyl esters of five known GAs (GA9, GA20, GA70, GA88, and 3-epi-GA88) were also identified as minor antheridiogens. In addition, four compounds corresponding to isomers of monohydroxy-GA73-Me were detected. One of these was shown to be 12[beta]-hydroxy-GA73-Me, the parent acid of which has been allocated the GA assignment GA96. The other three compounds, tentatively named X1, X2, and X3, have not been fully characterized. In L. flexuosum, GA73-Me was also identified as a major antheridiogen, with X2 being detected as a minor one. The total antheridium-formation activity in the culture medium of 7-week-old prothallia of L. circinnatum and L. flexuosum was more than 1000 times higher than that of L. japonicum. On the other hand, the response of gametophytes of the former two Lygodium ferns to GA73-Me was more than 100 times lower than that of L. japonicum.

["Vertigo" the fact analysis of clinical practice by ENT physicians of Chiba Prefecture by "send-out" questionnaires]

Despite the fact that vertigo has been one of the most frequent complaints encountered in daily practice in an ENT outpatient clinic, it is believed to be the most unwelcome subject for ENT physicians. The reasons are diverse; e.g., the understanding of vertigo is still a difficult task for most physicians and requires time-consuming multiple studies. However, answers to those questions, although speculated a posteriori, are yet to be substantiated. Therefore, we have analyzed the data obtained from multiple questionnaires that were addressed to ENT physicians practicing in Chiba Prefecture in November of 1993. However, those who work in publicly run hospitals were excluded from the study. The study included otorhinolaryngologists who were members of the Society of Otorhinolaryngology of Japan. We received filled questionnaire forms from 76 of 155 members (49%). The age ranged from 33 to 82 years (mean 55.8 years, 68 men and 8 women). From these questionnaires, it became apparent that physicians are not necessarily reluctant to see patients with vertigo. Instead, most ENT physicians appeared to be actively paying attention to this symptom and to be making efforts to approach its diagnosis and treatment. Although we are not certain if the data obtained here represent the majority of ENT physicians, the positive attitudes toward the patients with vertigo/dizziness would certainly encourage those of us who are interested in this particular symptom category.