Isolation and characterization of GBP28, a novel gelatin-binding protein purified from human plasma

By use of its affinity to gelatin-Cellulofine, a novel protein, GBP28 (gelatin-binding protein of 28 kDa), was obtained from human plasma. GBP28 bound to gelatin-Cellulofine could be eluted with 1 M NaCl. By analysis of its amino-terminal amino acid sequences and the peptides obtained by protease digestion, GBP28 was identified as a novel protein. After repeated gel chromatography of the 1 M NaCl eluate from gelatin-Cellulofine, about 50 micrograms of GBP28 was purified from 500 ml of human plasma. On gel chromatography, the protein migrated as a molecule of about 420 kDa. On SDS-PAGE, its molecular mass was 28 kDa under reducing conditions and 68 kDa under nonreducing conditions. Recently, human mRNA specific to adipose tissue, cDNA clone apM1, has been registered [Maeda, K., Okubo, K., Shimomura, I., Funahashi, T., Matsuzawa, Y., and Matsubara, K. (1996) Biochem. Biophys. Res. Commun. 221, 286-289]. The assumed amino acid sequence of cDNA clone apM1 contained all the sequences of GBP28 and its peptides. Therefore, it is evident that the cDNA clone apM1 encodes GBP28 and the protein is specific to adipose tissue. The clone encodes a polypeptide of 244 amino acids with a secretory signal sequence at the amino terminus, a small non-helical region, a stretch of 22 collagen repeats and a globular domain. Thus, GBP28 appears to belong to a family of proteins possessing a collagen-like domain through which they form homo-trimers, which further combine to make oligomeric complexes. Although its biological function is presently unclear, its adipocyte-specific expression suggests that GBP28 may function as an endogenous factor involved in lipid catabolism and storage or whole body metabolism.

Cloning and characterization of bfpTVW, genes required for the transcriptional activation of bfpA in enteropathogenic Escherichia coli

Expression of the bundle-forming pilus (BFP) of enteropathogenic Escherichia coli (EPEC) is regulated at the transcriptional level by growth phase, temperature, calcium and ammonium. Genes required for the transcriptional activation of bfpA were localized to a 1.8 kb fragment of the enteroadherent factor (EAF) plasmid of EPEC that is separated from the bfp operon by 6 kb. Within this fragment three identically oriented and closely spaced open reading frames (ORFs) were identified and designated bfpT, bfpV and bfpW. bfpT is predicted to encode a 31.8 kDa protein that shares homology with the AraC family of transcriptional regulators, including the presence of a conserved C-terminal DNA-binding helix-turn-helix motif. Insertional inactivation of bfpT led to the loss of bfpA transcription, BfpA protein production and the localized adherence (LA) phenotype; this mutant phenotype could be complemented by introduction of bfpTVW and, on separate plasmids, bfpT + bfpW. However, introduction of bfpT + bfpV, bfpV alone, bfpW alone, or bfpV + bfpW did not enable recovery of the wild-type phenotype. Maximal efficiency of bfpA transcription required all three genes, but bfpV and bfpW each enhanced transcription providing bfpT was also present. A series of deletions of the bfpA upstream promoter region was prepared; with respect to the bfpA transcription start site, sequence between nucleotides -94 and -55 was found to bind bfpT. BfpT also bound a DNA fragment containing the eaeA promoter region on the EPEC chromosome. From these results we conclude that bfpTV W causes transcriptional activation of bfpA, and possibly eaeA, by a trans-acting mechanism that may co-ordinately regulate the expression of EPEC virulence determinants.

Purification and characterization of a novel hyaluronan-binding protein (PHBP) from human plasma: it has three EGF, a kringle and a serine protease domain, similar to hepatocyte growth factor activator

A novel hyaluronan-binding protein (PHBP) was purified from human plasma by affinity chromatography on hyaluronan-conjugated Sepharose. The contaminating IgM and albumin in the partially purified preparation were removed with anti-IgG antibody-conjugated Sepharose and anti-albumin antibody-conjugated Sepharose, respectively, and no other contaminant was observed. Finally, 800 micrograms of PHBP was isolated from 500 ml of human plasma. PHBP gave a single 70-kDa band on SDS-PAGE under non-reducing conditions, and 50-kDa and 17-kDa bands under reducing conditions. Thus, PHBP was a heterodimer composed of 50-kDa and 17-kDa subunits, bridged by a disulfide linkage. Both subunits had novel N-terminal amino acid sequences, indicating that PHBP was a novel hyaluronan-binding protein in human plasma. The amino acid sequence deduced from the nucleotide sequence of the cloned PHBP cDNA exhibited significant homology to that of hepatocyte growth factor activator (HGFA). The results of Northern blot analysis indicated that liver, kidney, and pancreas expressed PHBP mRNA. The predicted structure of PHBP showed three epidermal growth factor (EGF) domains, a kringle domain and a serine protease domain, from its N-terminus, although HGFA has a fibronectin type II domain, an EGF domain, a fibronectin type I domain, an EGF domain, a kringle domain, and a serine protease domain, from its N-terminus.

Molecular cloning and expression of human liver biliverdin-IX beta reductase

The cDNA encoding for human liver isozyme I of biliverdin-IX beta reductase was cloned from human liver cDNA libraries. The constructed cDNA of 853 bp in length contained an entire reading frame coding 206 amino acid residues. It was found that isozyme 1 of biliverdin-IX beta reductase is identical to human erythrocyte NADPH-flavin reductase recently reported in a communication by Chikuba et al., Biochem. Biophys. Res. Commun., 198, 1170-1176 (1994). We, further, characterized this mRNA by Northern blot analyses of poly(A) RNA from four different human fetal tissues and eight different human adult tissues showed hybridization mainly to liver RNA in fetal tissues and to skeletal muscle and liver RNA in adult tissues. Southern blot analysis indicated that isozyme I of biliverdin-IX beta reductase appeared to be a single copy gene. Insertion of the enzyme-coding sequence into an expression vector pET-3c yielded relatively high amounts of the active enzyme in E. coli. The amino terminal sequence of the recombinant protein was identical to that of native enzyme, indicating that E. coli also removed the N-terminal methionine to produce the mature form. The recombinant and native biliverdin-IX beta reductases were indistinguishable as far as their mobility on SDS-PAGE gel, immunoreactivity and specific activity were concerned.

Isolation and characterization of the human inter-alpha-trypsin inhibitor family heavy chain-related protein (IHRP) gene (ITIHL1)

Inter-alpha-trypsin inhibitor (ITI) family heavy chain-related protein (IHRP) is a novel human glycoprotein that shows significant homology in amino acid sequence to proteins of the ITI family heavy chains from human plasma. Three overlapping clones that encode the human inter-alpha-trypsin inhibitor family heavy chain-related protein (IHRP) gene (ITIHL1) were isolated and characterized. The IHRP gene spans 15 kb and is composed of 24 exons from 27 to 207 bp in size with consensus splice sites. The gene codes for the precursor of IHRP, which is similar to inter-alpha-trypsin inhibitor (ITI) family heavy chains. Two major transcription initiation sites were identified in the 5'-flanking region. They contain putative promoter elements, but no typical TATA box. Some exons of this gene showed significant similarities to those of the ITI-H1 gene in nucleotide length and in intron phasing. The tissue-specific transcription of this gene may be due to the presence of binding sites for the hepatocyte nuclear factors LF-A1, HNF-5, NF-IL6, and C/EBP. This gene was found to be localized very close to another unknown gene related to EST (GenBank accession #: R54643, R50663, R50563, H27139, and R54913).

Primary structure of the pig homologue of human IHRP: inter-alpha-trypsin inhibitor family heavy chain-related protein

The pig counterpart of human IHRP has been isolated from pig serum, and cDNA clones encoding this counterpart were isolated and characterized. The amino acid sequence of pig IHRP predicted from the nucleotide sequence of its cDNA shows reasonable homology to that of human IHRP. The nucleotide sequence of pig IHRP cDNA is identical to that of the mRNA partially determined to be the heavy chain of pig ITI [Buchman et al. (1990) Surgery 108, 560-566]; it is one of the major mRNAs induced in pig liver on cardiogenic shock. Thus we concluded that the reported mRNA should code for IHRP and not for the heavy chain of ITI. The pig IHRP also seems to be identical to pig-MAP, which was recently reported to be a major acute phase serum protein in pig [Gonzalez-Roman et al. (1995) FEBS Lett. 371, 227-230]. The results suggest that IHRP might be involved in acute phase reactions.

Adjuvant oral chemotherapy to prevent recurrence after curative resection for hepatocellular carcinoma

Adjuvant oral chemotherapy was studied in 67 patients with stage II hepatocellular carcinoma who underwent curative resection between May 1988 and December 1990. Patients were stratified into two groups according to preoperative liver dysfunction: 55 had stage I disease (mild dysfunction) and 12 had stage II (moderate dysfunction). A randomized controlled study of postoperative oral administration of 1-hexylcarbamoyl-5-fluorouracil (HCFU) was conducted in each group. From October 1994 HCFU administration was suspended because of side-effects in nine patients with stage I liver dysfunction and in three with stage II dysfunction who had received the drug for more than 4 weeks. Cumulative survival and recurrence-free survival rates of patients with stage I disease in the treatment group were higher (P = 0.08 and P = 0.04 respectively) than those in the control group. However, in patients with stage II disease no significant difference was observed (P = 0.77 and P = 1.0 respectively). This study suggests that the potential benefits of HCFU on tumour recurrence should be weighed against the risk of adverse reactions in patients with mild liver dysfunction.

Identification of a novel virulence gene, virA, on the large plasmid of Shigella, involved in invasion and intercellular spreading

A novel virulence gene (virA) was identified upstream of the virG gene on the large plasmid of Shigella flexneri 2a YSH6000. Characterization of virA mutants infecting MK2 epithelial cell monolayers revealed that their invasive capacity was decreased to less than one fifth of the wild-type level. Nevertheless, the bacteria were capable of expressing and secreting IpaB, IpaC and IpaD proteins. The virA mutants were also impaired in their ability to spread intercellularly, since the bacteria gave rise to a small number of foci in a focus-plaque-forming test with MK2 cells. Although virG expression was slightly decreased in the virA mutants, introduction of a cloned virG gene into a virA mutant, N1945, failed to restore spreading ability. Although, introduction of a cloned virA gene into N1945 restored invasiveness and spreading ability, the reduced virG transcription level was not affected, indicating that the reduced virG expression in virA mutants does not play a major role in defective intercellular spreading. The nucleotide sequence of the virA region revealed that the virA gene was located 528 bp upstream of the virG gene, in the opposite orientation. The deduced amino acid sequence of the VirA protein indicated a 44.7 kDa protein with no homology to known proteins. The VirA protein was secreted into the culture supernatant, a process that required the Mxi and Spa loci. The expression of virA was under the control of the virB gene, the positive regulator of the ipa, mxi and spa operons. These results indicate that virA is a new member of the invasion regulon directed by virB and that the VirA function is involved in invasion and intercellular spreading.

[A long-term course of experimentally produced choroidal neovascularization in the rat]

We studied morphologically a long-term course of experimental choroidal neovascularization (ChNV) induced by krypton laser photocoagulation in the rat retina. Fifty-two weeks after photocoagulation, ChNV was enveloped completely by the retinal pigment epithelium. Vascular endothelial cells of ChNV were thin, with many fenestrations and wide lumen. The ChNV maintained the morphological characteristics of mature leaky capillaries similar to choriocapillaris. The lumen of the neovascularizations tended to be compressed by massive collagen fibers produced by the retinal pigmented epithelium. We found that experimental ChNV in the rat retina retains the characteristics of leaky capillaries for a long time unlike that in the monkey ChNV.

[Effects of interferon-beta on repair of the retinal pigment epithelium after laser photocoagulation]

We studied the morphological effects of human interferon-beta on repair of the retinal pigment epithelium (RPE) after moderate dye laser photocoagulation in monkey eyes. In the control eyes, RPE cells were proliferating towards the center from the margin of the laser burn 3 days after photocoagulation. At day 14 after photocoagulation, a newly formed monolayer of RPE cells covered Burch's membrane to repair the lesion. In the eyes treated with interferon-beta by systemic administration, RPE cells had proliferated remarkably 3 days after photocoagulation. The RPE cells proliferated to form multiple layers on Burch's membrane even at day 14 after photocoagulation. These results suggest that interferon-beta promotes the proliferation to repair damaged RPE.

Contact of Shigella with host cells triggers release of Ipa invasins and is an essential function of invasiveness

The invasion of colonic epithelial cells by Shigella, an early essential step for causing bacillary dysentery, is mediated by the IpaB, IpaC and IpaD proteins. Secretion of the Ipa proteins from Shigella requires functions encoded by the mxi and spa loci. In this study, we show that contact between the bacteria and epithelial cell triggers release of the Ipa proteins into the external medium, which results in a rapid decrease in levels of Ipa proteins presented on the cell surface. When the bacteria were used to infect polarized Caco-2 cells, release of Ipa proteins occurred efficiently from bacteria interacting with the basolateral surface rather than with the apical surface. Moreover, the interaction of bacteria with components of the extracellular matrix, such as fibronectin, laminin or collagen type IV, also stimulates the release of Ipa proteins. The release of Ipa proteins from Shigella required the surface-located Spa32 protein encoded by one of the spa genes on the large plasmid.

[Expression of fibroblast growth factor receptor 1 in experimental choroidal neovascularization with in situ hybridization]

Fibroblast growth factor (FGF) is an important factor for neovascularization in vivo. In order to clarify the role of FGF in experimentally produced choroidal neovascularization, we demonstrated mRNA for FGF receptor 1 in situ hybridization. Krypton laser photocoagulation was applied to the posterior retina of colored rats to produce choroidal neovascularization experimentally. These eyes were removed at several different intervals after photocoagulation. Chorioretinal section were used for in situ hybridization. FGF receptor 1 cDNA fragment was used to make antisense and sense probes for in situ hybridization. In normal chorioretinal tissue, staining indicating the existence of FGF receptor 1 mRNA was seen in the ganglion cell layer and inner nuclear layer. After the photocoagulation, the staining was seen in the retinal pigment epithelial cells, melanocytes in the choroid, and choroidal blood vessel wall in the photocoagulated lesions. FGF receptor 1 mRNA was expressed through the development of choroidal neovascularization, and it appears that FGF is necessary for development of choroidal neovascularization. Previous workers showed that the capillary endothelial cells and retinal pigment epithelial cells produce basic FGF in vitro. It seems that FGF effects those cells in an autocrine or paracrine manner in vivo.

Disulfide oxidoreductase activity of Shigella flexneri is required for release of Ipa proteins and invasion of epithelial cells

Secretion of IpaB, IpaC, and IpaD proteins of Shigella flexneri, essential for the invasion of epithelial cells, requires a number of proteins encoded by the spa and mxi loci on the large plasmid. Introduction of dsbA::Tn5 into S.flexneri from Escherichia coli K-12 reduced invasiveness, which resulted from a decrease in the capacity to release IpaB, IpaC, and IpaD proteins into the external medium. Examination of the surface-presented Ipa proteins of the dsbA mutant, however, revealed Ipa proteins at levels similar to those on wild-type cells. Since the defective phenotype was similar to that of the spa32 mutant of S. flexneri and the Spa32 sequence possessed two Cys residues, the effect of dsbA mutation of the folding structure of Spa32 under reducing conditions and on the surface expression of Spa32 was investigated. The results indicated that Spa32 was a disulfide-containing protein whose correctly folded structure was required for its presentation on the outer membrane. Indeed, replacing either one of the two Cys residues in Spa32 with Ser by site-directed mutagenesis reduced its capacity to release Ipa proteins into the external medium and led to the accumulation of Spa32 protein in the periplasm. These results indicated that the DsbA protein performs an essential function during the invasion of mammalian cells, by facilitating transport of the Spa32 protein across the outer membrane.

[The effect of interferon-beta on experimental choroidal neovascularization]

We studied histologically the effect of systemic administration of human interferon-beta (IFN-beta) on experimental choroidal neovascularization which was caused by intensive laser photocoagulation at the posterior pole of monkey eyes. The regression of choroidal neovascularization was observed in IFN-treated monkeys. Histologically, retinal pigment epithelium (RPE) was remarkably abundant around choroidal neovascularization in the subretinal space, and the activity of neovascularization was weaker in IFN-treated monkeys than in untreated monkeys. These results indicate that IFN-beta promotes the proliferation of RPE and suppresses the activity of endothelial cells of neovascularization to cause regression of choroidal neovascularization. The results suggest that IFN-beta is clinically useful to treat the choroidal neovascularization of age-related macular degeneration.

[Effect of human interferon-beta on reconstruction of the choriocapillaris in monkeys following laser photocoagulation]

We studied the effect of human interferon-beta on reconstruction of the choriocapillaris following laser photocoagulation in monkey eyes. Moderate dye laser photocoagulation caused the occlusion of the choriocapillaris by the intraluminal thrombus in the photocoagulated lesions on the retina. After 3 days, immature endothelial cells began to migrate towards the center from the edge of the lesions. After 7 days capillaries were newly formed, and after 14 days the choriocapillaris in the lesions was almost reconstructed. Systemic administration of interferon-beta after photocoagulation suppressed the reconstruction of the choriocapillaris remarkably. These results suggest that interferon-beta inhibits proliferation and migration of the capillary endothelium on the retina. Interferon-beta may be effective as medication for the treatment of age-related macular degeneration.

Determination of the active site of CD59 with synthetic peptides

CD59 inhibits the formation of membrane attack complex (MAC) of human complement by binding to C8 and C9 in the nascent membrane attack complex and inhibiting C9 binding to C8 in C5b-8 and C9 polymerization. Considering five disulfide bridges of CD59, we divided the molecule into two portions and synthesized the two peptides. One represented an amino-terminal half, P1-41, consisting of residues 1-41, while another represented a carboxyl-terminal half, P42-77, consisting of residues 42-77. P1-41 inhibited the MAC formation much more strongly than P42-77, indicating that the amino-terminal half contained the active site. We further synthesized P4-18 that consisted of residues 4-18 and P19-41 that consisted of residues 19-41. The activity of P4-18 was less than that of P19-41. Surprisingly, P19-41 showed higher activity than P1-41 and was comparable to urine CD59. Residues 19-41 were further divided into two portions: P20-25 which consisted of residues 20-25 and P27-38 which consisted of residues 27-38. Although their activities were significantly less than the activity of P19-41, P27-38 showed higher activity than P20-25. Residues 27-38 were further divided into three portions: P27-32 which consisted of residues 27-32, P30-34 which consisted of residues 30-34 and P33-38 which consisted of residues 33-38. When these peptides were assayed for the activities, all of them showed significant activities, even though they needed 10-fold more concentrations than P19-41. These data suggest that the portion made up of residues 27-38 is the active site constituting the binding site to C8 and C9.

Purification and characterization of a novel glycoprotein which has significant homology to heavy chains of inter-alpha-trypsin inhibitor family from human plasma

Plasmapheresis with a dextran sulfate column is a treatment for patients with hypercholesteremia. When proteins bound to the column during the treatment were fractionated to prepare some known proteins, we found a 57 kDa glycoprotein designated GP57 which showed a new N-terminal amino acid sequence. Western-blot analysis of human plasma revealed that only a 120 kDa protein, GP120, reacted with anti-GP57 antibody. Since GP120 and GP57 had an identical N-terminal amino acid sequence, GP120 is probably the intact form of GP57. The isoelectric point of GP120 was 6.8. N-Glycanase treatment decreased the molecular weight of GP120 by 15 kDa. Neuraminidase and O-glycanase, however, did not affect the molecular weight. Amino acid sequence analyses of the lysylendopeptidase digest of GP120 revealed significant homology to the heavy chains of inter-alpha-trypsin inhibitor (ITI) family. Since GP120 showed no bikunin sequence, and chondroitinase treatment and alkaline treatment of GP120 did not affect its molecular weight, we concluded that GP120 was not a complex with bikunin. We designated GP120 as IHRP (ITI heavy chain-related protein).

Thermoregulation of virB transcription in Shigella flexneri by sensing of changes in local DNA superhelicity

Transcription of the virB gene, a transcriptional regulator of invasion genes on the large plasmid of Shigella flexneri, is strictly regulated by growth temperature; when bacteria are grown at 37 degrees C, virB transcription is highly activated, while at 30 degrees C the level of virB transcription decreases to less than 5% of that at 37 degrees C. Transcription from the virB promoter is activated by VirF, which is encoded on the same plasmid, in a DNA superhelicity-dependent manner (T. Tobe, M. Yoshikawa, T. Mizuno, and C. Sasakawa, J. Bacteriol. 175:6142-6149, 1993). Here we provide evidence supporting the involvement of negative superhelicity in the thermoregulation of virB transcription. A local negatively supercoiled domain in the virB promoter region was created by activating a divergent transcription from the T7 RNA polymerase-dependent promoter, phi 10, which was placed upstream of the virB promoter in the opposite orientation. Transcription from the virB promoter was activated even at 30 degrees C by induction of divergent transcription. Levels of virB transcription correlated with levels of expressed T7 RNA polymerase. Transcriptional activation of virB by the system depended completely upon VirF function. The level of virB transcription achieved by introducing a negatively supercoiled domain was enough to give rise to expression of invasion capacity at 30 degrees C. These results indicated that the repression of virB transcription at 30 degrees C was caused by a reduction in negative superhelicity around the virB promoter region at 30 degrees C.

Cloning and characterization of cDNA for inter-alpha-trypsin inhibitor family heavy chain-related protein (IHRP), a novel human plasma glycoprotein

The cDNA encoding inter-alpha-trypsin inhibitor family heavy chain-related protein (IHRP) was cloned from human liver cDNA libraries. Oligonucleotide primers of human liver cDNA for PCR were constructed from internal amino acid sequences obtained with proteolytic fragments of IHRP. The amplified cDNA served as a hybridization probe for the screening of human liver cDNA libraries. The cDNA of 2,977 bp contained an entire reading frame coding 930 amino acids. The N-terminal 28 residues corresponded to a signal peptide for secretion. The N-terminal 600 residues of the mature form exhibited considerable homology to those of ITI heavy chains, while the C-terminal 300 residues showed no homology with the heavy chains and low homology with ATP-dependent proteases. IHRP was readily cleaved into 85- and 35-kDa fragments when plasma was incubated at 37 degrees C. The cleaved site, Arg-Arg-Leu, was within a proline-rich region. Northern blot analysis of poly(A) RNAs from various human tissues only showed hybridization to liver RNA.

Mapping of the newly identified biliverdin-IX beta reductase gene (BLVRB) to human chromosome 19q13.13-->q13.2 by fluorescence in situ hybridization

The human biliverdin-IX beta reductase gene (BLVRB) has been newly isolated from a human liver cDNA library. We now report the chromosome mapping of this gene by fluorescence in situ hybridization, using a 0.76-kb cDNA fragment as a probe. The BLVRB gene was localized to chromosome region 19q13.13-->q13.2.

Mapping of human inter-alpha-trypsin inhibitor family heavy chain-related protein gene (ITIHL1) to human chromosome 3p21-->p14

Inter-alpha-trypsin inhibitor family heavy chain-related protein (IHRP) is a novel glycoprotein isolated from human plasma. The cDNA encoding IHRP has recently been cloned from human liver cDNA libraries. We report the mapping of this gene (ITIHL1) by fluorescence in situ hybridization using a 2.5-kb cDNA fragment as a probe. ITIHL1 was localized to chromosome region 3p21-->p14 where the genes of heavy chain 1 and 3 of inter-alpha-trypsin inhibitor are located. This result, together with significant homology between the nucleotide sequences of ITIHL1 and the heavy chain genes, supports ITIHL1 as being a member of an evolutionary related gene family of ITI heavy chains. Northern blot analysis indicated that IHRP was predominantly synthesized in liver. From Southern blot analysis, it was tentatively concluded that ITIHL1 is a single copy gene.

Selective expression of monocyte chemotactic and activating factor/monocyte chemoattractant protein 1 in human blood monocytes by Mycobacterium tuberculosis

Neutrophils are the predominant leukocyte population in acute inflammation. Granulomatous inflammation such as tuberculosis is a specific type of chronic inflammation characterized by the predominant accumulation of macrophages. To clarify the mechanism of cellular recruitment in inflammation, the expression of chemokines, interleukin-8 and monocyte chemotactic and activating factor (MCAF)/monocyte chemoattractant protein 1 (MCP-1), was examined in human blood monocytes in response to lipopolysaccharide of Escherichia coli, which could induce acute inflammation, or purified protein derivative (PPD) or Mycobacterium tuberculosis, which could provoke chronic inflammation. Monocytes stimulated with PPD or M. tuberculosis expressed low levels of antigenic interleukin-8 but high levels of MCAF/MCP-1 compared with monocytes stimulated with lipopolysaccharide. Northern blot analysis showed the early induction of interleukin-8 mRNA and the delayed expression of MCAF/MCP-1 mRNA in response to PPD or M. tuberculosis. Thus, the disparate expression of chemokines may contribute to the cellular recruitment in acute and chronic inflammations.

[Experimental choroidal neovascularization in the rat]

We successfully produced, highly (78%) reproducible experimental choroidal neovascularization (ChNV) in the subretinal space of pigmented rats with intense diode laser photocoagulation. ChNV in the pigmented rat was characterized by rapid development of neovascular membrane and proliferation of retinal pigment epithelium in the subretinal space. This procedure may be useful as an experimental model for ChNV.

vacC, a virulence-associated chromosomal locus of Shigella flexneri, is homologous to tgt, a gene encoding tRNA-guanine transglycosylase (Tgt) of Escherichia coli K-12

The genetic determinants required for invasion of epithelial cells by Shigella flexneri and for the subsequent bacterial spreading are encoded by the large virulence plasmid. Expression of the virulence genes is under the control of various genes on the large plasmid as well as on the chromosome. We previously identified one of the virulence-associated loci near phoBR in the NotI-C fragment of the chromosome of S. flexneri 2a YSH6000 and designated the locus vacC. The vacC mutant showed decreased levels of IpaC, and IpaD proteins as well as transcription of ipa, an operon essential for bacterial invasion (N. Okada, C. Sasakawa, T. Tobe, M. Yamada, S. Nagai, K. A. Talukder, K. Komatsu, S. Kanegasaki, and M. Yoshikawa, Mol. Microbiol. 5:187-195, 1991). To elucidate the molecular nature of the vacC locus, we cloned the vacC region from YSH6000 on a 1.8-kb SalI-BamHI DNA fragment. The nucleotide sequence of the 1,822-bp vacC clone was highly (> 98%) homologous to the tgt region of Escherichia coli K-12, which is located at 9.3 min on the linkage map. Complementation tests indicated that the vacC function was encoded by an open reading frame expressing a 42.5-kDa protein, which corresponded to the tgt gene of E. coli K-12, coding for tRNA-guanine transglycosylase (Tgt) (K. Reuter, R. Slany, F. Ullrich, and H. Kersten, J. Bacteriol. 173:2256-2264, 1991). The cloned tgt gene from E. coli K-12 restored the virulence phenotype to the vacC mutant of YSH6000. Characterization of the vacC mutant indicated that levels of VirG, a protein essential for bacterial spreading, and VirF, the positive regulator for the expression of the virG and ipaBCD operons, decreased significantly compared with those of the wild type. Similar phenotypic changes occurred in vacC mutants constructed by insertion of a neomycin resistance gene in shigellae and enteroinvasive E. coli strains, consistent with the hypothesis that the vacC (tgt) gene contributes to the pathogenicity of Shigella flexneri.

[The role of repeat transurethral resection in stage A1 carcinoma of the prostate]

In order to evaluate the significance of repeat transurethral resection (TUR) in differentiating stage A1 prostatic adenocarcinoma from those with stage A2, we performed repeat TUR in 34 patients with an initial diagnosis of stage A1 prostatic adenocarcinoma. It was found that residual adenocarcinoma was present in five cases (14.7%), but the diagnosis was changed from stage A1 to stage A2 in only one case (2.9%). In one patient with final diagnosis of stage A1 carcinoma, bone metastases were detected seven months after the repeat TUR. It was concluded that repeat TUR for stage A1 prostatic adenocarcinoma did not yield clinically significant information.