Roles of His-79 and Tyr-180 of D-xylose/dihydrodiol dehydrogenase in catalytic function

Mammalian dimeric dihydrodiol dehydrogenase is identical with d-xylose dehydrogenase and belongs to a protein family with prokaryotic proteins including glucose-fructose oxidoreductase. Of the conserved residues in this family, either His-79 or Tyr-180 of d-xylose/dihydrodiol dehydrogenase has been proposed to be involved in the catalytic function. Site-directed mutagenesis was used to examine the roles of the two residues of the monkey enzyme. A mutant, Y180F, was almost inactive, but, similarly to the wild-type enzyme, exhibited high affinity for NADP(H) and fluorescence energy transfer upon binding of NADPH. The H79Q mutation had kinetically largest effects on K(d) (>7-fold increase) and K(m) (>25-fold increase) for NADP(H), and eliminated the fluorescence energy transfer. Interestingly, the dehydrogenase activity of this mutant was potently inhibited with a 190-fold increase in the K(m) for NADP(+) by high ionic strength, which activated the activity of the wild-type enzyme. These results suggest a critical role of Tyr-180 in the catalytic function of this class of enzymes, in addition to functions of His-79 in the coenzyme binding and chemical steps of the reaction.

Flavonoid constituents from Glycyrrhiza glabra hairy root cultures

An unusual biflavonoid named licoagrodin was isolated from the hairy root cultures of Glycyrrhiza glabra (Leguminosae) along with three prenylated retrochalcones, licoagrochalcones B, C, D, a prenylated aurone, licoagroaurone and four known prenylated flavonoids, licochalcone C, kanzonol Y, glyinflanin B and glycyrdione A. From the glycosidic fraction, a isoflavone glycoside, licoagroside A, and a maltol glycoside, licoagroside B were isolated together with four known isoflavone glycosides, two flavone C-glycosides, and three other glycosides. Their structures were elucidated on the basis of spectroscopic evidence.

Filamentous fungus Aspergillus oryzae has two types of alpha-1,2-mannosidases, one of which is a microsomal enzyme that removes a single mannose residue from Man9GlcNAc2

alpha-Mannosidase activities towards high-mannose oligosaccharides were examined with a detergent-solubilized microsomal preparation from a filamentous fungus, Aspergillus oryzae. In the enzymatic reaction, the pyridylaminated substrate Man(9)GlcNAc(2)-PA was trimmed to Man(8)GlcNAc(2)-PA which lacked one alpha-1,2-mannose residue at the nonreducing terminus of the middle branch (Man8B isomer), and this mannooligosaccharide remained predominant through the overall reaction. Trimming was optimal at pH 7.0 in PIPES buffer in the presence of calcium ion and kifunensine was inhibitory with IC(50) below 0.1 microM. These results suggest that the activity is the same type as was previously observed with human and yeast endoplasmic reticulum (ER) alpha-mannosidases. Considering these results together with previous data on a fungal alpha-1,2-mannosidase that trimmed Man(9)GlcNAc(2) to Man(5)GlcNAc(2) (Ichishima, E., et al. (1999) Biochem J, 339: 589-597), the filamentous fungi appear to have two types of alpha-1,2-mannosidases, each of which acts differently on N-linked mannooligosaccharides.

Coronary atherosclerosis in youths in Kyushu Island, Japan: histological findings and stenosis

We histologically examined the coronary arteries of 52 autopsied cases of the youths (3 to 39 years of age, mean 28.5 years) in Kyushu island, Japan, without clinical events of coronary artery diseases. The coronary artery specimens were taken from the proximal portions of the right coronary artery (Seg. 1), the left anterior descending artery (Seg. 6), and the macroscopically most stenotic region (ST). Atherosclerotic lesions were histologically classified into four types: concentric fibrous, eccentric fibrous, concentric lipid rich, or eccentric lipid-rich type. The degrees of stenosis (< 25%, 25-50%, 50 75%, > 75%) were morphometrically evaluated. The majority of coronary arteries with under 50% stenosis were of the concentric fibrous type. Lipid-rich types of coronary atherosclerosis increased in the coronary arteries with over 50% stenosis and were observed in the Seg. 6 and ST, while 70% of Seg. 1 lesions with over 50% stenosis were of a fibrous type. Serum cholesterol levels of patients with a lipid rich type of coronary atherosclerosis were significantly higher than those with a fibrous type. These results suggested that the early stage of coronary atherosclerosis in Japanese youths is mainly of a concentric fibrous type, which later develops to a lipid rich type. Hypercholesterolemia would promote the progression of atherosclerosis.

Biosynthesis of the dimethylallyl moiety of glabrol in Glycyrrhiza glabra hairy root cultures via a non-mevalonate pathway

Incorporation of [1-13C]glucose indicates that the biosynthesis of the hemiterpene moiety of glabrol, the main prenylated flavanone in the hairy root cultures of Glycyrrhiza glabra, proceeds via a glyceraldehyde/pyruvate non-mevalonate pathway.

Phosphotransacetylase as a key factor in biological production of polyhydroxybutyrate

Phosphotransacetylase (Pta) catalyzes the reversible conversion of acetyl-coenzyme A (CoA) to acetyl phosphate. Polyhydroxybutyrate (PHB) synthase and accumulation were compared between a Pta-deficient mutant and the wild-type Escherichia coli, which were transformed with pAE100, coding for 3-ketothiolase, NADPH-dependent acetoacetyl-CoA reductase, and PHB synthase from Ralstonia eutropha. During the growth period, PHB synthase activity in the Pta-deficient mutant was lower than that in the wild type. PHB accumulation in the Pta-deficient mutant, however, was higher than that in wild-type cells grown in Luria-Bertani (LB) medium containing 1% glucose (high C:N ratio). The Pta-deficient mutant showed PHB accumulation even in LB medium (low C:N ratio), whereas wild-type cells showed no PHB accumulation. These data suggest the activation of PHB synthase by acetyl phosphate that is synthesized by Pta. A decrease in Pta activity probably causes some increase in acetyl-CoA as substrate for the PHB synthesis pathway, resulting in increased PHB accumulation.

Effect of light/dark cycle on bacterial hydrogen production by Rhodobacter sphaeroides RV. From hour to second range

Hydrogen production by photosynthetic bacteria provides an efficient energy conversion method under low light intensity. However, under strong illumination, such as midday sunlight, the efficiency drops. This prevents the method from being applied industrially. To overcome this problem, we examined a method to thin out the excessive illumination. Light was given intermittently to reduce the total energy flux. The on/off ratio was set at 1/1 throughout the study, so that the time average of the light energy flux became half the continuous illumination. By keeping the time-average light flux constant (0.6 kW.m-2), the effects of the cycle period were examined in the range of hours to seconds. The hydrogen production rate was greatly affected by the cycle period, but cell growth and substrate consumption rates remained almost constant. The 30-min light/dark cycle (30 min on and 30 min off) provided the highest rate of hydrogen production (22 L.m-2.24 h-1). At the shorter cycles, the rate decreased except that there was a suboptimum at about 40 s. Under excessive light intensity (1.2 kW.m-2), the light-to-hydrogen conversion efficiency was greatly enhanced. The hydrogen production rate during the 30-min cycle was twice as high as during a 12-h cycle under the same conditions.

Polyhydroxybutyrate production from carbon dioxide by cyanobacteria

Genetic characterization and enhancement of polyhydroxybutyrate (PHB) accumulation in cyanobacteria were investigated for efficient PHB production from CO2. The genome DNAs in the PHB-accumulating strains Synechococcus sp. MA19 and Spirulina platensis NIES46 retained the highly homologous region to phaC of Synechocystis PCC6803, whereas low homology was detected in the nonaccumulating strains Synechococcus sp. PCC7942 and Anabaena cylindrica NIES19. Synechococcus sp. MA19, which accumulates PHB up to 30% of dry cell weight from CO2 as the sole carbon source, was mutated by insertion of transposon Tn5 to enhance the PHB accumulation. Genetic and physiological analysis of the mutant indicated that decreased phosphotransacetylase activity could trigger an increase of acetyl coenzyme A leading to enhancement of PHB accumulation. PHB synthase in Synechococcus sp. MA19 was probably attached to thylakoid membrane since PHB granules were associated with pigments. A genetically engineered cyanobacteria retaining soluble PHB synthase from Ralstonia eutropha accumulated pigment-free PHB granules, which is an advantage for the purification of PHB.

Neurocutaneous vascular hamartomas mimicking Cobb syndrome. Case report

The authors report the rare case of a patient with neurocutaneous vascular hamartomas mimicking Cobb syndrome. An 8-year-old boy was admitted to the authors' hospital with progressive urinary disturbance and upper back pain. Multiple skin nevi had been noted at the child's birth. Radiological examination revealed multiple cavernous angiomas in the spinal cord in the same metamere in which the skin nevi had been observed and also in the left cerebral hemisphere. His symptoms gradually improved without surgical intervention. Four years later he was readmitted because of a cerebral hemorrhage involving the left cerebral peduncle. Nonsurgical treatment was chosen because his symptoms promptly improved. To the best of the authors' knowledge, this is the first case of multiple cavernous angiomas in the brain and spinal cord associated with skin nevi. The authors discuss this clinical entity and the significance of the disease.

Rotatory motion of a cemented acetabular component caused by aseptic loosening and dissociation of the polyethylene liner: a case report

A 63-year-old woman without rheumatoid arthritis who had undergone cemented total hip arthroplasty developed coxalgia 1 year later. Radiography showed a clear zone at the cement-implant interface and rotatory motion of the acetabular component, so revision surgery was performed 4.5 years after the first operation. Aseptic loosening was noted and 7 spacers outside the acetabular component were broken and buried under the cement mantle. We consider that the rotatory motion may be caused by circumferential loosening of the acetabular component stemming from incomplete implant fixation and also dissociation of the ultra-high-molecular weight polyethylene (UHMWPE) liner from the metal base plate.

Construction of a physical and transcript map flanking the imprinted MEST/PEG1 region at 7q32

MEST/PEG1, a gene expressed paternally in mesodermal derivatives in early embryonic stages, is the first imprinted gene mapped to chromosome 7q32. Since imprinted genes are clustered in general at a chromosomal region, we speculated that a similar imprinted-gene cluster may exist at chromosome region 7q32 and that the functions of some such genes may contribute to the phenotype of Silver-Russell syndrome including maternal uniparental disomy for chromosome 7 (maternal UPD7). As an initial step toward the isolation of imprinted genes at 7q32, we adopted an integrated approach involving the construction of a PAC contig and ESTs mapping in the vicinity of MEST. Here, we have constructed a complete contig of PAC and BAC clones and a transcript map spanning the entire approximately 1-Mb region between D7S530 and D7S649. We developed 60 novel STSs and precisely mapped 47 genes/ESTs. This map contains a putative autistic disorder locus that has been suggested to be localized near markers D7S530 and D7S684. This integrated physical and transcript map provides a valuable resource for identification of an imprinted gene(s) in this region as well as a candidate gene(s) for autistic disorder.

Postoperative hyponatremia in a patient with ACTH-producing Merkel cell carcinoma

Merkel cell carcinoma is characterized by specific neuroendocrine features and the expression of several neuropeptides. We report a case of Merkel cell carcinoma with post-surgical hyponatremia in an 85-year-old Japanese woman. A tumor on the left cheek histopathologically showed the characteristics of Merkel cell carcinoma together with Bowen's disease. Although an increased level of ACTH was found both in the tumor and in the peripheral blood, the postoperative hyponatremia in our patient seems more likely to have been caused by the stress of the operation and indapamide, considering that the ACTH level in the tumor was much lower than those in other ectopic ACTH-producing tumors in previous reports.

Radiographic evaluation of bioactive glass-ceramic grafts in postero-lateral lumbar fusion

STUDY DESIGN

Follow-up study of bioactive glass-ceramic graft for postero-lateral fusion (PLF) in the lumbar spine was performed using plain radiography.

OBJECTIVES

To investigate the fusion state of the porous stick type of bioactive glass-ceramic which has been used in PLF in the lumbar spine, by plain radiography, and to evaluate the usefulness of this technique.

METHODS

Fourteen patients who underwent PLF using apatite and wollastonite-containing glass-ceramic (A-W. GC) were followed-up for more than 1 year and 6 months by plain radiography.

RESULTS

Six patients who were followed up for more than 2 years were considered to have obtained subtotal or total fusion.

CONCLUSION

PLF using A-W. GC mixed with autologous grafted bone can preserve bone stock without the need to harvest a bone graft from the iliac crest and will be useful for PLF in the lumbar spine.

Heterologous expression of clostridial hydrogenase in the Cyanobacterium synechococcus PCC7942

The Clostridium pasteurianum hydrogenase I has been expressed in the cyanobacterium Synechococcus PCC7942. The Shine-Dalgarno sequence of the structural gene encoding hydrogenase I from C. pasteurianum was changed to that of the cat (chloramphenicol acetyltransferase) gene. The hydrogenase gene was cloned downstream of a strong promoter, isolated from Synechococcus PCC7942, with the cat gene as a reporter gene. Expression of clostridial hydrogenase was confirmed by Western and Northern blot analyses in Synechococcus and Escherichia coli, whereas in vivo/in vitro measurements and activity staining of soluble proteins separated on non-denaturing polyacrylamide gels revealed functional expression of hydrogenase only in cyanobacterial cells. The changed Shine-Dalgarno sequence appeared to be essential for the functional expression of clostridial hydrogenase in Synechococcus, but had no influence on the expression and activity of clostridial hydrogenase expressed in E. coli.

Synthesis of neoglycoenzymes with homogeneous N-linked oligosaccharides using immobilized endo-beta-N-acetylglucosaminidase A

A procedure for the enzymatic synthesis of neoglycoenzymes is described. The gene encoding endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae (Endo-A) was overexpressed in Escherichia coli as a fusion protein linked to glutathione S-transferase (GST). GST-Endo-A fusion was extracted as a soluble protein. The fusion protein was purified to homogeneity with glutathione-Sepharose 4B and showed transglycosylation activity toward high-mannose-type glycopeptides without removing the GST moiety. The GST-Endo-A immobilized on glutathione-Sepharose 4B retained its transglycosylation activity. The immobilized enzyme could transfer (Man)(6)GlcNAc en bloc to partially deglycosylated ribonuclease B without damaging its enzyme activity. The immobilized GST-Endo-A should be very useful for synthesizing active neoglycoenzymes attached with homogeneous N-linked oligosaccharides.

Plate assay for endo-β-N-acetylglucosaminidase activity using a chromogenic substrate synthesized by transglycosylation with Arthrobacter Endo-β-N-acetylglucosaminidase

The transglycosylation activity of Arthrobacter endo-beta-N-acetylglucosaminidase (Endo-A) was used for the enzymatic synthesis of a novel oligosaccharide, Man6GlcNAc-5-bromo-4-chloro-3-indolyl-beta-glucoside (Man6GlcNAc-Glc-beta-X). Various endo-beta-N-acetylglucosaminidases hydrolyzed this oligosaccharide, producing Man6GlcNAc and Glc-beta-X. The E. coli strains coexpressing Endo-A and beta-glucosidase formed blue colonies in the presence of Man6GlcNAc-Glc-beta-X. Therefore, endo-beta-N-acetylglucosaminidase activity could be directly detected by the plate assay. This simple plate assay is useful for screening microorganisms for endo-beta-N-acetylglucosaminidase activity.

COLLABORATIVE WORK TO EVALUATE TOXICITY ON MALE REPRODUCTIVE ORGANS BY REPEATED DOSE STUDIES IN RATS : 4)FADROZOLE HYDROCHLORIDE : AN ORAL 2/4-WEEK MALE REPRODUCTIVE ORGAN TOXICITY STUDY

Doses of 0, 30 and 60 mg/kg/day of fadrozole hydrochloride (Afema: non-steroidal aromatase inhibitor, antitumor agent) were given perorally by gavage to HanIbm WIST male rats from 6 or 8 weeks of age for 2 weeks, and from 6 weeks of age for 4 weeks. In all treatment groups, reduced weights of seminal vesicle, prostate and epididymis, and degeneration/necrosis of the pachytene spermatocytes in stages VII or VIII seminiferous tubules, were dose-relatedly observed. Effects could also be assessed quantitatively by staging analysis with the result of a reduction in the numbers of stage VII pachytene spermatocytes at 30 and 60 mg/kg/day. Epididymal sperm examination revealed no treatment-related changes in any groups. The effects of 4-week treatment on male reproductive organs were similar to those of 2-week treatment at the same dose levels, except for the weights of seminal vesicle and prostate, which were more reduced by 4-week treatment than by 2-week treatment. There was no notable difference in detectability of toxicity in male reproductive organs between 2-week treatment from 6 weeks of age and 2-week treatment from 8 weeks of age. It was concluded that the changes observed in the rat male reproductive organs following 4 weeks of treatment with fadrozole hydrochloride could be detected also with 2 weeks of treatment.

Dynamic Ca2+ signalling in rat arterial smooth muscle cells under the control of local renin-angiotensin system

1. We visualized the changes in intracellular Ca2+ concentration ([Ca2+]i), using fluo-3 as an indicator, in individual smooth muscle cells within intact rat tail artery preparations. 2. On average in about 45 % of the vascular smooth muscle cells we found spontaneous Ca2+ waves and oscillations ( approximately 0.13 Hz), which we refer to here as Ca2+ ripples because the peak amplitude of [Ca2+]i was about one-seventh of that of Ca2+ oscillations evoked by noradrenaline. 3. We also found another pattern of spontaneous Ca2+ transients often in groups of two to three cells. They were rarely observed and are referred to as Ca2+ flashes because their peak amplitude was nearly twice as large as that in noradrenaline-evoked responses. 4. Sympathetic nerve activity was not considered responsible for the Ca2+ ripples, and they were abolished by inhibitors of either the Ca2+ pump in the sarcoplasmic reticulum (cyclopiazonic acid) or phospholipase C (U-73122). 5. Both angiotensin antagonists ([Sar1,Ile8]-angiotensin II and losartan) and an angiotensin converting enzyme inhibitor (captopril) inhibited the Ca2+ ripples. 6. The extracellular Ca2+-dependent tension borne by unstimulated arterial rings was reduced by the angiotensin antagonist by approximately 50 %. 7. These results indicate that the Ca2+ ripples are generated via inositol 1,4, 5-trisphosphate-induced Ca2+ release from the intracellular Ca2+ stores in response to locally produced angiotensin II, which contributes to the maintenance of vascular tone.

Invasion of the lacrimal system by basal cell carcinoma

BACKGROUND

The rate of recurrence of basal cell carcinoma (BCC) in the periorbital region is higher than that in other areas because of the spread of the tumor along barrier structures.

OBJECTIVE

A better understanding of the biological behavior of BCC in this area, in particular as it relates to the lacrimal system, should improve the outcome of surgery.

METHODS

A study was made of two cases of BCC that developed in the periorbital region and invaded the lacrimal system.

RESULTS

The tumors were found to have invaded the lacrimal system along the mucosal epithelium. Magnetic resonance imaging (MRI) did not suggest any abnormalities in this area. In one patient, the tumor had infiltrated the nasal cavity without destruction of the periorbital bone and nasal cartilage. A preoperative fiberscopic examination clearly demonstrated the involvement of the nasal cavity in this case.

CONCLUSION

The lacrimal system is often invaded by BCC that originates from the periorbital region. Physicians and surgeons need to be well aware of the possibility of such aggressive infiltration by BCC.

Susceptibility to testicular germ-cell tumours in a 129.MOLF-Chr 19 chromosome substitution strain

The identification of genes that control susceptibility to testicular germ-cell tumours (TGCTs), the most common cancer affecting young men, has been difficult. In laboratory mice, TGCTs arise from primordial germ cells in only the 129 inbred strains, and susceptibility is under multigenic control. The spontaneously arising mutation Ter (ref. 5) on mouse chromosome 18 (Refs 6,7) increases TGCT frequency on a 129/Sv background. We originally used Ter in genetic crosses to identify loci that control tumorigenesis. A genome scan of tumour-bearing progeny from backcrosses between the 129/Sv-Ter/+ and MOLF/Ei strains provided modest evidence that MOLF-derived alleles on chromosome 19 enhance development of bilateral TGCTs (ref. 9). To obtain independent evidence for linkage to the MOLF chromosome, we made an autosomal chromosome substitution strain (CSS; or 'consomic strain') in which chromosome 19 of 129/Sv+/+ was replaced by its MOLF-derived homologue. The unusually high frequency of TGCTs in this CSS (even in the absence of the Ter mutation) provides evidence confirming the genome survey results, identifies linkage for a naturally occurring strain variant allele that confers susceptibility to TGCTs and illustrates the power of CSSs in complex trait analysis.

The mRNA for protease nexin-1 is expressed in human dermal papilla cells and its level is affected by androgen

Protease nexin-1, an inhibitor of serine proteases, plays important parts in the regulation of the growth, differentiation, and death of cells by modulating proteolytic activity. The mRNA for protease nexin-1 accumulates in rat dermal papilla cells in a hair cycle-dependent fashion and its levels are well correlated with the ability of dermal papilla cells to support hair growth. In an attempt to characterize the potential role of protease nexin-1 as a modulator of hair growth in humans, we investigated the steady-state level of protease nexin-1 mRNA in cultured human dermal papilla cells using a semiquantitative technique that involved reverse transcription and polymerase chain reaction, as well as the localization of this mRNA in vivo using dissected hair follicles. Protease nexin-1 mRNA was expressed in all dermal papilla cells examined, and it was also identified in the lower part of the connective tissue sheath. Moreover, we found that levels of protease nexin-1 mRNA were depressed by dihydrotestosterone, the most potent androgen, in cultured dermal papilla cells obtained from balding scalp. Our results suggest that protease nexin-1 might be a key molecule in the control of hair growth in humans and, moreover, that the androgen-mediated downregulation of the synthesis of protease nexin-1 might be associated with the progression of male-pattern baldness.

Novel distribution of adrenomedullin-immunoreactive cells in human tissues

Adrenomedullin (AM) is a novel hypotensive and vasodilator peptide. We previously examined the localization of AM in human, rat, and porcine tissues using a polyclonal antibody against synthetic human AM[40-52]. We demonstrated that AM is widely distributed in the endocrine and neuroendocrine systems, but not in the heart, kidney, or blood vessels, although high levels of AM mRNA were detected in the latter tissues. In this study, we further investigated the distribution of AM by using two newly developed monoclonal antibodies against synthetic human AM peptides, [12-25] and [46-52]. AM immunoreactivity was observed in cardiac myocytes, vascular smooth muscle cells, endothelial cells, and renal distal and collecting tubules. In addition, AM-immunoreactive (IR) cells were found in mucosal and glandular epithelia of the digestive, respiratory, and reproductive systems, as well as the endocrine and neuroendocrine systems. These findings indicate that AM-IR cells are more widely distributed in human tissues and suggest that AM might play multiple biological roles in humans.