The granaticin biosynthetic gene cluster of Streptomyces violaceoruber Tü22: sequence analysis and expression in a heterologous host

BACKGROUND

The granaticins are members of the benzoisochromanequinone class of aromatic polyketides, the best known member of which is actinorhodin made by Streptomyces coelicolor A3(2). Genetic analysis of this class of compounds has played a major role in the development of hypotheses about the way in which aromatic polyketide synthases (PKSs) control product structure. Although the granaticin nascent polyketide is identical to that of actinorhodin, post-PKS steps involve different pyran-ring stereochemistry and glycosylation. Comparison of the complete gene clusters for the two metabolites is therefore of great interest.

RESULTS

The entire granaticin gene cluster (the gra cluster) from Streptomyces violaceoruber T-22 was cloned on either of two overlapping cosmids and expressed in the heterologous host, Streptomyces coelicolor A3(2), strain CH999. Chemical analysis of the recombinant strains demonstrated production of granaticin, granaticin B, dihydrogranaticin and dihydrogranaticin B, which are the four known metabolites of S. violaceoruber. Analysis of the complete 39,250 base pair sequence of the insert of one of the cosmids, pOJ466-22-24, revealed 37 complete open reading frames (ORFs), 15 of which resemble ORFs from the act (actinorhodin) gene cluster of S. coelicolor A3(2). Among the rest, nine resemble ORFs potentially involved in deoxysugar metabolism from Streptomyces spp. and other bacteria, and six resemble regulatory ORFs.

CONCLUSIONS

On the basis of these resemblances, putative functional assignments of the products of most of the newly discovered ORFs were made, including those of genes involved in the PKS and tailoring steps in the biosynthesis of the granaticin aglycone, steps in the deoxy sugar pathway, and putative regulatory and export functions.

The NDP-sugar co-substrate concentration and the enzyme expression level influence the substrate specificity of glycosyltransferases: cloning and characterization of deoxysugar biosynthetic genes of the urdamycin biosynthetic gene cluster

BACKGROUND

Streptomyces fradiae is the principal producer of urdamycin A. The antibiotic consists of a polyketide-derived aglycone, which is glycosylated with four sugar components, 2x D-olivose (first and last sugar of a C-glycosidically bound trisaccharide chain at the 9-position), and 2x L-rhodinose (in the middle of the trisaccharide chain and at the 12b-position). Limited information is available about both the biosynthesis of D-olivose and L-rhodinose and the influence of the concentration of both sugars on urdamycin biosynthesis.

RESULTS

To further investigate urdamycin biosynthesis, a 5.4 kb section of the urdamycin biosynthetic gene cluster was sequenced. Five new open reading frames (ORFs) (urdZ3, urdQ, urdR, urdS, urdT) could be identified each one showing significant homology to deoxysugar biosynthetic genes. We inactivated four of these newly allocated ORFs (urdZ3, urdQ, urdR, urdS) as well as urdZ1, a previously found putative deoxysugar biosynthetic gene. Inactivation of urdZ3, urdQ and urdZ1 prevented the mutant strains from producing L-rhodinose resulting in the accumulation of mainly urdamycinone B. Inactivation of urdR led to the formation of the novel urdamycin M, which carries a C-glycosidically attached D-rhodinose at the 9-position. The novel urdamycins N and O were detected after overexpression of urdGT1c in two different chromosomal urdGT1c deletion mutants. The mutants lacking urdS and urdQ accumulated various known diketopiperazines.

CONCLUSIONS

Analysis of deoxysugar biosynthetic genes of the urdamycin biosynthetic gene cluster revealed a widely common biosynthetic pathway leading to D-olivose and L-rhodinose. Several enzymes responsible for specific steps of this pathway could be assigned. The pathway had to be modified compared to earlier suggestions. Two glycosyltransferases normally involved in the C-glycosyltransfer of D-olivose at the 9-position (UrdGT2) and in conversion of 100-2 to urdamycin G (UrdGT1c) show relaxed substrate specificity for their activated deoxysugar co-substrate and their alcohol substrate, respectively. They can transfer activated D-rhodinose (instead of D-olivose) to the 9-position, and attach L-rhodinose to the 4A-position normally occupied by a D-olivose unit, respectively.

Association of distinct clinical subsets with myositis-specific autoantibodies towards anti-155/140-kDa polypeptides, anti-140-kDa polypeptides, and anti-aminoacyl tRNA synthetases in Japanese patients with dermatomyositis: a single-centre, cross-sectional study

OBJECTIVE

To determine the association of distinct clinical subsets with myositis-specific autoantibodies (MSAs) towards anti-155/140-kDa polypeptides [anti-155/140 antibodies (Abs)], anti-140-kDa polypeptides (anti-140 Abs), and anti-aminoacyl tRNA synthetases (ARS Abs) in Japanese patients with dermatomyositis (DM).

METHODS

We compared the clinical features and short-term prognoses of 30 DM patients whose serological status included these MSAs. The MSAs were determined by immunoprecipitation.

RESULTS

Anti-155/140 Abs (n = 5), anti-140 Abs (n = 8), and anti-ARS Abs (n = 7) did not overlap each other. All of the anti-155/140 Ab-positive patients (n = 5) were complicated by malignancies, as were all of the anti-140 Ab-positive patients (n = 8), who showed rapidly progressive interstitial lung disease (ILD). The survival rate at 6 months from the diagnosis of DM was significantly lower in the anti-140 Ab-positive patients than in the other patients.

CONCLUSION

This is the first study to report, in a single cohort of DM patients, that distinct clinical subsets are distributed in an anti-155/140 Ab-positive group, an anti-140 Ab-positive group, or an anti-ARS Ab-positive group. Our data also confirm previous evidence that anti-155/140 Abs are involved in malignancies and that anti-140 Abs are involved in rapidly progressive ILD.

Endostatin peptide, an inhibitor of angiogenesis, prevents the progression of peritoneal sclerosis in a mouse experimental model

Peritoneal sclerosis is a major and serious complication in patients on long-term continuous ambulatory peritoneal dialysis (PD). The involvement of angiogenesis and proangiogenic factors such as vascular endothelial growth factor (VEGF)-A in progressing peritoneal sclerosis has been reported. We previously reported the therapeutic efficacy of endostatin peptide, a potent inhibitor of angiogenesis derived from type XVIII collagen, in a mouse diabetic nephropathy model. Here, we examined the therapeutic effect of endostatin peptide in preventing progression in a mouse peritoneal sclerosis model. Male ICR mice received intraperitoneal injections of chlorhexidine gluconate (CG) every other day to induce peritoneal sclerosis. Endostatin peptide (1 or 4 mg/kg/day) was administered via subcutaneously implanted osmotic minipumps. Peritoneal sclerosis (day 24) was significantly suppressed by endostatin peptide in a dose-dependent manner. Peritoneal accumulation of type III collagen was significantly suppressed by endostatin peptide. Increase in the number of CD31(+) blood vessels, F4/80(+) monocyte/macrophage accumulation, and 5-bromodeoxyuridine(+) proliferating cells was significantly inhibited by endostatin peptide. Increase in peritoneal expression of VEGF-A, profibrotic transforming growth factor-beta1, and alpha-smooth muscle actin was suppressed by endostatin peptide. Immunoreactivity for endogenous endostatin (whole molecule) and endostatin receptor alpha5beta1-integrin was increased and colocalized to CD31(+) blood vessels in the thickened peritonea of CG-injected mice. These results demonstrate the potential use of antiangiogenic endostatin peptide as a novel therapeutic agent in preventing peritoneal sclerosis, a severe complication in patients undergoing long-term PD.

Crystal structures of the Streptomyces coelicolor TetR-like protein ActR alone and in complex with actinorhodin or the actinorhodin biosynthetic precursor (S)-DNPA

Actinorhodin, an antibiotic produced by Streptomyces coelicolor, is exported from the cell by the ActA efflux pump. actA is divergently transcribed from actR, which encodes a TetR-like transcriptional repressor. We showed previously that ActR represses transcription by binding to an operator from the actA/actR intergenic region. Importantly, actinorhodin itself or various actinorhodin biosynthetic intermediates can cause ActR to dissociate from its operator, leading to derepression. This suggests that ActR may mediate timely self-resistance to an endogenously produced antibiotic by responding to one of its biosynthetic precursors. Here, we report the structural basis for this precursor-mediated derepression with crystal structures of homodimeric ActR by itself and in complex with either actinorhodin or the actinorhodin biosynthetic intermediate (S)-DNPA [4-dihydro-9-hydroxy-1-methyl-10-oxo-3-H-naphtho-[2,3-c]-pyran-3-(S)-acetic acid]. The ligand-binding tunnel in each ActR monomer has a striking hydrophilic/hydrophobic/hydrophilic arrangement of surface residues that accommodate either one hexacyclic actinorhodin molecule or two back-to-back tricyclic (S)-DNPA molecules. Moreover, our work also reveals the strongest structural evidence to date that TetR-mediated antibiotic resistance may have been acquired from an antibiotic-producer organism.

Two sequence elements of glycosyltransferases involved in urdamycin biosynthesis are responsible for substrate specificity and enzymatic activity

BACKGROUND

Two deoxysugar glycosyltransferases (GTs), UrdGT1b and UrdGT1c, involved in urdamycin biosynthesis share 91% identical amino acids. However, the two GTs show different specificities for both nucleotide sugar and acceptor substrate. Generally, it is proposed that GTs are two-domain proteins with a nucleotide binding domain and an acceptor substrate site with the catalytic center in an interface cleft between these domains. Our work aimed at finding out the region responsible for determination of substrate specificities of these two urdamycin GTs.

RESULTS

A series of 10 chimeric GT genes were constructed consisting of differently sized and positioned portions of urdGT1b and urdGT1c. Gene expression experiments in host strains Streptomyces fradiae Ax and XTC show that nine of 10 chimeric GTs are still functional, with either UrdGT1b- or UrdGT1c-like activity. A 31 amino acid region (aa 52-82) located close to the N-terminus of these enzymes, which differs in 18 residues, was identified to control both sugar donor and acceptor substrate specificity. Only one chimeric gene product of the 10 was not functional. Targeted stepwise alterations of glycine 226 (G226R, G226S, G226SR) were made to reintroduce residues conserved among streptomycete GTs. Alterations G226S and G226R restored a weak activity, whereas G226SR showed an activity comparable with other functional chimeras.

CONCLUSIONS

A nucleotide sugar binding motif is present in the C-terminal moiety of UrdGT1b and UrdGT1c from S. fradiae. We could demonstrate that it is an N-terminal section that determines specificity for the nucleotide sugar and also the acceptor substrate. This finding directs the way towards engineering this class of streptomycete enzymes for antibiotic derivatization applications. Amino acids 226 and 227, located outside the putative substrate binding site, might be part of a larger protein structure, perhaps a solvent channel to the catalytic center. Therefore, they could play a role in substrate accessibility to it.

Chemical characterisation of disruptants of the Streptomyces coelicolor A3(2) actVI genes involved in actinorhodin biosynthesis

The actVI genetic region of Streptomyces coelicolor A3(2) is part of the biosynthetic gene cluster of actinorhodin (ACT), the act cluster, consisting of six ORFs: ORFB, ORFA, ORF1, ORF2, ORF3, ORF4. A newly devised method of ACT detection with a combination of HPLC and LC/MS was applied to the analysis of the disruptants of each ORF. ACT was produced by those of ORFB, ORFA, ORF3, and ORF4. Instead of ACT, the ORF1 disruptant produced 3,8-dihydroxy-1-methylanthraquinone-2-carboxylic acid (DMAC) and aloesaponarin II as shunt products. The ORF2 disruptant gave 4-dihydro-9-hydroxy-1-methyl-10-oxo-3-H-naphtho-[2,3-c]-pyran-3-(S)-acet ic acid, (S)-DNPA. These results support our previous proposal for stereospecific pyran ring formation in the biosynthesis of ACT, most importantly suggesting that the actVI-ORF2 product would recognize (S)-DNPA as a substrate for stereospecific reduction at C-15. The disruptant of ORFA produced (S)-DNPA together with ACT, suggesting that actVI-ORFA might play a role such as stabilising the multicomponent, type II PKS complex.

New steroidal saponins from the rhizomes of Anemarrhena asphodeloides Bunge (Liliaceae)

From the rhizome of Anemarrhena asphodeloides Bunge (Liliaceae), four new steroidal saponins named anemarrhenasaponins I-IV (1-4) were isolated, together with known saponins, timosaponin A-III (5), marcogenin diglycoside (6) and timosaponin B-II (7) and a xanthone C-glycoside, mangiferin. These saponins are coprostane type steroidal glycosides. Their structures were established on the basis of spectroscopic and chemical evidence.

Noninvasive measurement of blood glucose concentrations by analysing Fourier transform infra-red absorbance spectra through oral mucosa

Whether Fourier transform infra-red spectroscopy with an attenuated total reflection prism could be applied for noninvasive glucose measurement through oral mucosa was evaluated. As a result, the same absorbance peak at 1033 cm-1 as in glucose aqueous solution was found in the absorbance spectra through mucous membrane. However, these glucose specific peaks were interfered with by the baseline drifts owing to prism attachment and the background spectra from body constituents other than glucose. Therefore, to eliminate these interferences, the calibration curve between the second derivatives of the absorbance peak at 1033 cm-1 and those at 2920 cm-1 was calculated (r = 0.910). By using this calibration curve, the spectral changes due to prism attachment were first eliminated. Secondly, by obtaining the second derivative of the difference between the postprandial absorbance peak and the fasting sample as a characteristic of an individual, high correlations between the corrected second derivatives of absorbance spectra through the mucous membrane of the lip at 1033 cm-1 and the increases in blood glucose concentrations above fasting levels were observed (r = 0.910). In conclusion, it was suggested that Fourier transform infra-red spectroscopy could be useful for noninvasive monitoring of glucose through oral mucosa.

Proof that the ACTVI genetic region of Streptomyces coelicolor A3(2) is involved in stereospecific pyran ring formation in the biosynthesis of actinorhodin

Pyran ring formation in the biosynthesis of actinorhodin in Streptomyces coelicolor A3(2) was studied using the act cluster deficient strain, CH999, carrying pRM5-based plasmids harbouring combinations of the actVI genes. The strain, CH999/pIJ5660 (pRM5 + actVI-ORF1), produced a chiral intermediate, (S)-DNPA, suggesting that the actVI-ORF1 product is a reductase determining the C-3 stereochemical centre.

Antitumor activity of dextran derivatives immobilizing platinum complex (II)

The in vivo antitumor activity and toxicity of a newly synthesized polymeric prodrug of cisplatin was investigated and also compared with plain cisplatin. The prodrug included a dicarboxymethyl-dextran conjugate of cisplatin (DCM-Dex/CDDP). DCM-Dex/CDDP was i.v. injected in mice bearing s.c. Colon 26 mouse colon cancer cells. The tissue distribution of platinum was thereafter determined by flameless atomic absorption spectrophotometry. The platinic concentration of the organs showed a high rate of retention at 24 h after injection in the DCM-Dex/CDDP-treated mice. No biochemical or hematologically adverse effects were observed. In addition, DCM-Dex/CDDP showed a significantly higher antitumor activity than cisplatin alone. These results indicate that DCM-Dex/CDDP may therefore be a potentially effective cancer chemotherapy.

Increased production of inflammatory cytokines in cultured CD4+ cells from patients with HTLV-I-associated myelopathy

We investigated the production of inflammatory cytokines derived from cultured T cells of peripheral blood lymphocytes (PBL) in 14 patients with HTLV-I-associated myelopathy (HAM). The production of inflammatory cytokines, such as tumor necrosis factor-alpha, interferon-gamma, and granulocyte-macrophage colony stimulating factor, was significantly increased in patients with HAM, compared to HTLV-I seronegative controls. On the contrary, interleukin-4 production in cultured T cells was detected in only two patients with HAM, and not detected in HTLV-I seronegative controls. These results suggest that the production of inflammatory cytokines derived from TH1 cell population was simultaneously exaggerated in HAM patients. Interestingly, accelerated production of these cytokines was derived from CD4+ cells, which are main target cells in HTLV-I infection. These findings suggest that an inflammatory state in the central nervous system might be related to the pathogenesis of HAM.

IL-15 is a biomarker involved in the development of rapidly progressive interstitial lung disease complicated with polymyositis/dermatomyositis

BACKGROUND

Polymyositis/dermatomyositis (PM/DM) is an autoimmune disease that is sometimes complicated with rapidly progressive interstitial lung disease (RPILD). However, serum and lung biomarkers that can predict RPILD development remain unclear.

OBJECTIVES

To determine potential serum and lung biomarkers that can predict RPILD development in patients with PM/DM-ILD.

METHODS

In total, 49 patients with PM/DM-ILD were enrolled. We measured the serum levels of 41 cytokines/chemokines, ferritin and anti-MDA5 antibody, compared them between the RPILD (n = 23) and non-RPILD (n = 26) groups, and ranked them by their importance through random forest analysis. To distinguish the two groups, we determined biomarker combinations by logistic regression analysis. We also measured the bronchoalveolar lavage fluid (BALF) levels of 41 cytokines/chemokines. Using immunohistochemistry, we examined IL-15 expression in lung tissues. The IL-15 production was also investigated using A549 and BEAS-2B cells.

RESULTS

The RPILD group had significantly higher IL-15, IL-1RA, IL-6, CXCL10, VCAM-1, anti-MDA5 antibody and ferritin serum levels than the non-RPILD group, but it had a significantly low CCL22 level. Meanwhile, anti-MDA5 antibody, IL-15, CXCL8, CCL22, IL-1RA and ferritin were the best combination to distinguish the two groups. IL-15 and CCL22 were also predictive marker for RPILD development in anti-MDA5 antibody-positive patients. Additionally, the RPILD group had significantly high IL-15 levels in BALF. The lung tissues expressed IL-15, which increased after cytokine stimulation in the A549 cells.

CONCLUSION

This study identified a combination of biomarkers predicting PM/DM-RPILD progression, and IL-15 is an important cytokine for predicting RPILD development and reflecting ILD severity.

Presence of serum anti-human T-lymphotropic virus type I (HTLV-I) IgM antibodies means persistent active replication of HTLV-I in HTLV-I-associated myelopathy

We investigated serum IgM antibodies against human T-lymphotropic virus type I (HTLV-I) in 29 HTLV-I associated myelopathy (HAM) patients and 34 HTLV-I carriers, using western blot analysis. Anti-HTLV-I IgM was detected in all 6 post-transfusional HAM patients and in 19 of 23 (83%) HAM patients with no history of blood transfusion, but in only 4 of 21 (19%) HTLV-I carriers. In HAM patients, HTLV-I proviral DNA integrated into peripheral blood lymphocyte (PBL) was detected by Southern blot analysis in all of the 6 (100%) and 18 of the 23 (78%). In contrast, it was detected in only 2 of 25 (8%) HTLV-I carriers. For the serum anti-HTLV-I IgM and HTLV-I provirus in PBL, the differences between the HAM and HTLV-I carriers were statistically significant (P less than 0.01). Our data indicate that the increased HTLV-I proviral DNA in PBL is produced by the persistent active replication of HTLV-I in HAM. Furthermore, Southern blot analysis showed intense bands in HAM patients with histories of blood transfusion, in whom the progression of the disease had been rapid. We conclude that the persistent active replication of HTLV-I is an important factor in the pathogenesis of HAM.

A new mode of stereochemical control revealed by analysis of the biosynthesis of dihydrogranaticin in Streptomyces violaceoruber Tü22

A class of Streptomyces aromatic polyketide antibiotics, the benzoisochromanequinones, all shows trans stereochemistry at C-3 and C-15 in the pyran ring. The opposite stereochemical control found in actinorhodin (3S, 15R, ACT) from S. coelicolor A3(2) and dihydrogranaticin (3R, 15S, DHGRA) from S. violaceoruber Tü22 was studied by functional expression of the potentially relevant ketoreductase genes, actIII, actVI-ORF1, gra-ORF5, and gra-ORF6. A common bicyclic intermediate was postulated to undergo stereospecific reduction to provide either the 3-(S) or the 3-(R) configuration of an advanced intermediate, 4-dihydro-9-hydroxy-1-methyl-10-oxo-3-H-naphtho[2,3-c]pyran-3-acetic acid (DNPA). Combinations of the four ketoreductase genes were coexpressed with the early biosynthetic genes encoding a type II minimal polyketide synthase, aromatase, and cyclase. gra-ORF6 was essential to produce (R)-DNPA in DHGRA biosynthesis. Out of the various recombinants carrying the relevant ketoreductases, the set of gra-ORF5 and -ORF6 under translational coupling (on pIK191) led to the most efficient production of (R)-DNPA as a single product, implying a possible unique cooperative function whereby gra-ORF6 might encode a "guiding" protein to control the regio- and stereochemical course of reduction at C-3 catalyzed by the gra-ORF5 protein. Updated BLAST-based database analysis suggested that the gra-ORF6 product, a putative short-chain dehydrogenase, has virtually no sequence homology with the actVI-ORF1 protein, which was previously shown to determine the 3-(S) configuration of DNPA in ACT biosynthesis. This demonstrates an example of opposite stereochemical control in antibiotic biosynthesis, providing a key branch point to afford diverse chiral metabolic pools.

Increased adherence of T cells to human endothelial cells in patients with human T-cell lymphotropic virus type I-associated myelopathy

We investigated the adherence of T cells to human umbilical vein endothelial cells in seven patients with human T-lymphotropic virus type I (HTLV-I)-associated myelopathy. The adherence of T cells to endothelial cells increased significantly in all the patients with HTLV-I-associated myelopathy when compared with the adherence in the seronegative controls (1.3- to 2.8-fold) and compared with the adherence in the anti-HTLV-I-seropositive non-HTLV-I-associated myelopathy carriers (1.4- to 2.8-fold). Prior treatment of the endothelial cell monolayer with recombinant interferon gamma (50 IU/mL) enhanced the T cell-endothelial cell adhesion in both the controls and patients with HTLV-I-associated myelopathy. However, values after prior treatment in the patients with HTLV-I-associated myelopathy were significantly higher than those in seronegative controls and carriers. The results suggest that the significantly increased T cell-endothelial cell adherence may be related to the initial stages of lymphocyte migration from the blood to the central nervous system in patients with HTLV-I-associated myelopathy.

Abnormal glucagon response to arginine and its normalization in obese hyperinsulinaemic patients with glucose intolerance: importance of insulin action on pancreatic alpha cells

An excessive glucagon secretion to intravenous arginine infusion was found in obese hyperinsulinaemic patients with glucose intolerance. This study was designed to determine whether the glucagon hyperresponsiveness to arginine in these patients would improve by insulin infused at a high enough dose to overcome insulin resistance. By infusing high dose insulin during arginine infusion, the previously exaggerated glucagon response to arginine could be normalized. To normalize the abnormal glucagon response, insulin doses of 4.2 +/- 0.7 and 3.8 +/- 0.5 IU were required during arginine infusion in obese hyperinsulinaemic patients with impaired glucose tolerance and Type 2 (non-insulin-dependent) diabetes mellitus, respectively. This achieved plasma peak insulin levels 3 to 4 times higher than those observed in non-obese healthy subjects. Furthermore, we clarified whether or not the effect of normalizing insulin action and/or glycaemic excursions contributed to normalizing the exaggerated glucagon response to arginine in these patients. Blood glucose was clamped while high dose insulin was infused at the same levels as observed during the arginine infusion test with no insulin infusion. As a result, normalization of the exaggerated plasma glucagon response was achieved, whether hyperglycaemia existed or not. These results clearly demonstrate that, similar to non-obese hypoinsulinaemic Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetic patients, the exaggerated Alpha-cell response to arginine infusion in obese hyperinsulinaemic patients with glucose intolerance is secondary to the reduction of insulin action on the pancreatic Alpha cell, and that the expression of insulin action plays an important part in normalizing these abnormalities.

Characterization of adherent T cells to human endothelial cells in patients with HTLV-I-associated myelopathy

To clarify the phenomenon of increased adherence of T cells to endothelial cells (EC) in patients with HTLV-I-associated myelopathy (HAM), we determined the surface markers and expression of lymphocyte function antigen-1 (LFA-1) in T cells adherent or nonadherent to EC. The percentage of activated or HLA-DR+ T cells and the expression of LFA-1 in the adherent cell population were significantly higher than those in the nonadherent cell population. Moreover, the CD4 to CD8 ratio of the HLA-DR+ cells in the EC-adherent T cells was significantly higher than that in the nonadherent cells. Collectively, these results indicate that increased adherence of T cells to EC in HAM patients is based on the increase of activated T cells with high density LFA-1 expression in the peripheral blood. Moreover, CD4+ HLA-DR+ cells exhibited more adhesive activity to EC than CD8+ HLA-DR+ cells, suggesting that activated CD4+ cells, rather than activated CD8+ cells, may be important as the first trigger for T cell-infiltration to the central nervous system in the immunopathogenesis of HAM.

Functional complementation of pyran ring formation in actinorhodin biosynthesis in Streptomyces coelicolor A3(2) by ketoreductase genes for granaticin biosynthesis

A mutation in actVI-ORF1, which controls C-3 reduction in actinorhodin biosynthesis by Streptomyces coelicolor, was complemented by gra-ORF5 and -ORF6 from the granaticin biosynthetic gene cluster of Streptomyces violaceoruber Tü22. It is hypothesized that, while gra-ORF5 alone is a ketoreductase for C-9, gra-ORF6 gives the enzyme regiospecificity also for C-3.

Active production of anti-human T-lymphotropic virus type I (HTLV-I) IgM antibody in HTLV-I-associated myelopathy

We investigated the presence of anti-human T-lymphotropic virus type I (HTLV-I) IgM in sera and cerebrospinal fluid from patients with HTLV-I-associated myelopathy (HAM) by Western blot analysis. Analyses of 36 serum samples revealed that most patients (31/36; 86.1%) had anti-HTLV-I IgM, whereas only four of 23 (17.4%) HTLV-I carriers had it. In studies of cerebrospinal fluid, anti-HTLV-I IgM was detected in 24 of 36 (66.7%) HAM patients, whereas none was detected in nine HTLV-I carriers. The differences were statistically significant (p less than 0.01). These results suggest that persistent active replication of HTLV-I occurs in the central nervous system as well as in the peripheral blood of HAM patients, and may contribute to the development of HAM.

In vitro characteristics and in vivo plasma disposition of cisplatin conjugated with oxidized and dicarboxymethylated dextrans

In vitro release behavior and cytotoxic activity, and in vivo plasma disposition of newly synthesized macromolecular derivatives of cisplatin (CDDP) were investigated and compared with CDDP. The derivatives included oxidized dextran conjugate of CDDP (OX-Dex/CDDP) and dicarboxymethylated dextran conjugate of CDDP (DCM-Dex/CDDP). In vitro release of platinum complex from dextran conjugated CDDP was determined by an equilibrium dialysis method. These dextran conjugates showed sustained release of the platinum complex. In vitro release half-life for DCM-Dex/CDDP was significantly longer (4.5 times) than that for OX-Dex/CDDP. In vitro cytotoxic activity of CDDP and dextran conjugated CDDP against colon 26, mouse colon cancer cell line, was measured using the MTT assay method. OX-Dex/CDDP showed a similar cytotoxic activity to CDDP. However, both cytotoxic activities were markedly decreased when preincubated with the medium containing serum. On the other hand, DCM-Dex/CDDP retained residual cytotoxic activity at a significantly higher level than OX-Dex/CDDP after preincubation with the medium containing serum, although it showed the lowest cytotoxic activity. This indicated longer maintenance of the in vitro antitumor activity of DCM-Dex/CDDP in serum compared with OX-Dex/CDDP. Plasma disposition of CDDP and dextran conjugated CDDP was determined by intravenous administration to rats. Although the total platinum plasma concentration-time profile for OX-Dex/CDDP was similar to that for CDDP, its markedly higher profile was achieved when DCM-Dex/CDDP was administered. The values of the total platinum AUC and MRT, where AUC is the area under the platinum concentration-time curve and MRT is the mean residence time, for DCM-Dex/CDDP were 11.2 times and 4.8 times significantly higher than with OX-Dex/CDDP in plasma, respectively. DCM-Dex/CDDP also showed a significantly lower total clearance compared with OX-Dex/CDDP. These results from the in vivo experiments revealed that retention of DCM-Dex/CDDP in blood circulation was much greater than that for OX-Dex/CDDP. DCM-Dex/CDDP thus has potential as a macromolecular derivative of CDDP for passive tumor targeting.

Exaggerated messenger RNA expression of inflammatory cytokines in human T-cell lymphotropic virus type I-associated myelopathy

OBJECTIVE

To investigate the expression of inflammatory cytokine messenger RNA (mRNA) in peripheral blood mononuclear cells of patients with human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM).

PATIENTS

Seventeen patients with HAM, 18 HTLV-I-seropositive carriers, and 10 seronegative individuals were studied.

MAIN OUTCOME MEASURE

We compared the expression of tumor necrosis factor alpha (TNF-alpha), granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon alpha (IFN-alpha), IFN-beta, and IFN-gamma, and interleukin 1 alpha (IL-1 alpha) and IL-1 beta by reverse transcriptase-polymerase chain reaction.

RESULTS

In patients with HAM, the reverse transcriptase-polymerase chain reaction products of TNF-alpha, GM-CSF, IFN-gamma, and IL-1 alpha were detected in significantly higher incidences than in HTLV-I-seropositive carriers and seronegative controls. Furthermore, simultaneous mRNA expression of three or more of these four cytokines was detected in all patients with HAM compared with only 21.4% of HTLV-I-seropositive carriers. By contrast, there was no significant difference in mRNA expression of IFN-alpha, IFN-beta, and IL-1 beta among patients with HAM, HTLV-I-seropositive carriers, and HTLV-I-seronegative controls.

CONCLUSIONS

An exaggerated mRNA expression of several inflammatory cytokines, including TNF-alpha, GM-CSF, IFN-gamma, and IL-1 alpha, was demonstrated in peripheral blood mononuclear cells of patients with HAM. Moreover, transcripts of these cytokines were simultaneously up-regulated in patients with HAM, suggesting that an inflammatory state in the central nervous system may be related to the pathogenesis of HAM.

Effect of alpha 2-adrenoceptor antagonist on platelet activation during insulin-induced hypoglycaemia in type 2 (non-insulin-dependent) diabetes mellitus

The role of epinephrine in platelet activation and the effect of an alpha 2-adrenoceptor antagonist, midaglizole, during insulin-induced hypoglycaemia in Type 2 (non-insulin-dependent) diabetes mellitus were examined. The action of midaglizole as a platelet alpha 2-antagonist was confirmed by in vitro studies using platelet-rich plasma and washed platelet suspension. Hypoglycaemia was induced by a bolus injection of short-acting insulin in 24 diabetic patients. They were divided into two groups, a control group (n = 12) and an alpha 2-group (n = 12), and midaglizole was administered orally 60 min before insulin injection in the latter. Blood glucose and plasma C-peptide levels were significantly decreased (p less than 0.005) by insulin injection in both groups. Counter-regulatory hormones, including epinephrine, and arginine vasopressin were similarly increased at the hypoglycaemic nadir compared with the levels at 0 min in both groups. Plasma beta-thromboglobulin was increased at the hypoglycaemic nadir (165.5 +/- 12.6 ng/ml) compared with the level at 0 min (121.0 +/- 11.5, p less than 0.005) in the control group, whereas no significant increase was demonstrated in the alpha 2-group. These results suggest that plasma epinephrine plays an important role in platelet activation during hypoglycaemia in Type 2 diabetes mellitus, and that the platelet activation is prevented by alpha 2-adrenoceptor antagonist.