Genome organization of human 48-kDa oligosaccharyltransferase (DDOST)

The enzyme oligosaccharyltransferase (dolichyl-diphosphooligosaccharide-protein glycosyltransferase; EC 2. 4.1.119) (DDOST) catalyzes the transfer of a high-mannose oligosaccharide (GlcNac2Man9Glc3) from a dolichol-linked oligosaccharide donor (dolichol-P-GlcNac2Man9Glc3) onto the asparagine acceptor site within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains across the membrane of the endoplasmic reticulum. We isolated mouse and human DDOST cDNAs from retinoic acid-treated mouse P19 EC cells and human NT-2 cells, respectively. DDOST mRNA is expressed intensely in heart and pancreas, but at lower levels in brain. Here we show that the human DDOST 48-kDa subunit gene (HGMW-approved symbol DDOST) is organized into 11 exons expanding about 9 kb. This DDOST subunit gene is localized on chromosome 1p36.1 by fluorescence in situ hybridization analysis.

GS-164, a small synthetic compound, stimulates tubulin polymerization by a similar mechanism to that of Taxol

PURPOSE

During our search for new microtubule effectors as anticancer agents, we have found that a small synthetic molecule designated GS-164 interferes with the assembly of porcine microtubule proteins and has cytotoxic activity against a wide range of human tumor cell lines. In this study, we investigated mode of action of the compound in comparison with Taxol and colcemid.

METHODS

To gain an insight into the mode of action of GS-164, we used an in vitro microtubule polymerization assay and a flow-cytometric measurement technique. Microtubule organization and the level of tubulin polymerization in HeLa cells were also examined by immunofluorescence microscopy and cytoskeletal protein analyses, respectively.

RESULTS

GS-164 stimulated assembly of microtubule proteins in vitro in a concentration-dependent and a GTP-independent manner. Furthermore, as with Taxol, the microtubule polymerization induced by GS-164 was antagonized by podophyllotoxin, a tubulin polymerization inhibitor, and microtubules formed by GS-164 were resistant to disassembly by calcium or low temperatures. GS-164 in the micromolar range arrested the cell cycle of HeLa cells in the mitotic phase leading to cell death. GS-164 also increased the amounts of cellular microtubules in HeLa cells, resulting in the formation of microtubule bundles.

CONCLUSION

These results indicate that GS-164 stimulates microtubule assembly by a similar mechanism to that of Taxol. A comparative conformational analysis of GS-164 and Taxol suggested that the structure of the former mimics the minimum essential sites of Taxol required to exert the Taxol-like activities described above. Although the cytotoxicity of GS-164 against human tumor cells was 1000-fold lower than that of Taxol and GS-164 was one-tenth as active as Taxol in vitro, these findings pave the way for synthesizing clinically useful anticancer agents using GS-164 as a lead compound.

High-speed holographic microscopy for fast-propagating cracks in transparent materials

A method of high-speed holographic microscopy is developed to take three successive microscopic photographs of a crack tip propagating in a transparent poly(methyl methacrylate) specimen at a speed of several hundred meters per second. When a crack is propagating in a specimen, three Q-switched ruby lasers emit three laser pulses successively. The time interval between each laser pulse and the next is 1 mus or longer. An optical system of angle-multiplexing holography records the crack as three successive holograms on one photographic plate. Crack images are reconstructed and photographed through a conventional microscope. The spatial resolution of the reconstructed images is approximately 114 lines/mm. From the photographs, one can measure crack speed, crack opening displacement, and the dynamic stress intensity factor. The high-speed holographic microscopy makes it possible to study rapid crack propagation in microseconds.

Mechanism of nitric oxide-dependent killing of Mycobacterium bovis BCG in human alveolar macrophages

We demonstrated that products of the L-arginine-dependent pathway of human alveolar macrophages (AM) effectively kill the Mycobacterium bovis bacillus Calmette-Guérin (BCG) in vitro. The formation of products was triggered by inoculation with BCG itself. Many reports have shown that activated rodent AM could produce an amount of nitric oxide (NO) sufficient to suppress the growth of mycobacteria. However, there have been no definitive results as to whether human AM might have the NO-dependent mechanism for the killing of mycobacteria. Therefore, we have undertaken some experiments to answer this question. Immunofluorescence assays showed an increased production of inducible nitric oxide synthase (iNOS) and peroxynitrite in BCG-inoculated AM from patients with pulmonary fibrosis. Reverse transcriptase-PCR also revealed the higher expression of iNOS-coding mRNA. Colony assays demonstrated that these human AM effectively killed BCG in their cytoplasm. However, treatment of AM with N(G)-monomethyl-L-arginine monoacetate resulted in markedly reduced killing activity. These results clearly show that BCG-induced NO and its reactive product with the oxygen radical peroxynitrite could play an important role in the killing of BCG in human AM.

[A clinical evaluation of the Hepcon/HMS: a new device of monitoring hemostasis management during cardiopulmonary bypass]

BACKGROUND

The "Hepcon/HMS", a small, protable console which can instantaneously measure residual whole blood heparin concentration and automatically compute the necessary dose of additional heparin during extracorporeal circulation and also compute the required dose of protamine to reverse the effect of residual heparin.

METHOD

This study was performed in 32 consecutive patients undergoing primary elective cardiac operation between March and July 1996. Patients were divided randomly in two groups: control group and "Hepacon/HMS" group. Hematologic factors, total heparin dose, total protamine dose, postoperative bleeding and blood transfusion volume were compared between these two groups.

RESULTS

Patients in the "Hepcon/HMS" group received significantly greater doses of heparin (p = 0.01) and lower doses of protamine (p = 0.01) compared with the control patients.

CONCLUSION

By using "Hepcon/HMS", smaller amount of protamine to reverse residual heparin was achieved without no hemostatic derangement nor increase in the amount of postoperative bleeding, irrespective of the fact that the greater amount of heparin was administered during extracorporeal circulation as compared with the conventional anticoagulation protocol. It may help prevent the undesirable side effects of administering excessive amount of protamine, including depression of myocardial function, platelet dysfunction, anaphylactic reaction and catastrophic circulatory collapse.

[Type III procollagen N-terminal aminopeptide and type IV collagen 7S in pleural effusion fluid]

The mechanism of pleural fibrosis in malignant and inflammatory pleural effusion remains unclear. We measured the levels of type III procollagen N-terminal amino peptide (PIIIP) and type IV collagen 7S in patients who had pleural effusion and lung carcinoma, and in others who had inflammatory diseases (parapneumonic and tuberculous pleuritis). The PIIIP level and the PIIIP/type IV collagen 7S ratio in patients with malignant pleural effusion were significantly lower than those in patients with inflammatory pleural effusion (p < 0.01), but the levels of type IV collagen 7S did not differ. The ratio of PIIIP to type IV collagen 7S was higher in patients with tuberculous pleuritis than in those with parapneumonic pleuritis (p < 0.05). These data indicate that pleural fibrotic adhesion may be accelerated in inflammatory pleural effusion because of elevated production of type III collagen; basement membrane injury in malignant and inflammatory pleural effusion may be caused by similar damage. We conclude that a high level of PIIIP and a high PIIIP/type IV collagen 7S ratio may indicate the presence of inflammatory pleuritis, and that the latter may indicate the presence of tuberculous pleuritis.

Nitric oxide as an inflammatory mediator of radiation pneumonitis in rats

Radiation pneumonitis is a major complication of radiation therapy. To elucidate the mechanisms of radiation-induced pneumonitis, we studied nitric oxide (NO) produced from lung tissues using a model of unilaterally irradiated rats. Our results demonstrated that alveolar macrophages (AM) produced NO after irradiation, and the expression of inducible NO synthase (NOS) in both AM and alveolar epithelial cells was increased. Furthermore, the progression of radiation pneumonitis was reduced with the in vivo treatment of the NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). The effect of L-NAME was further confirmed by the inhibition of mRNA expression for procollagen-alpha1 type III of the lung. With these results, NO produced from AM and alveolar epithelial cells after irradiation may be an important mediator in the progression of radiation pneumonitis.

Stoichiometry of subunits and heme content of hemoglobin from the earthworm Lumbricus terrestris

The extracellular hemoglobin (Hb) of the earthworm, Lumbricus terrestris, has four major O2-binding chains, a, b, c (forming a disulfide-linked trimer), and d ("monomer"). Additional structural chains, "linkers," are required for the assembly of the approximately 200-polypeptide molecule. The proportion of linker chains had been reported to be one-third of the total mass on the basis of densitometry of Coomassie Blue-stained SDS-gels. Reverse-phase high performance liquid chromatography (HPLC), however, gave 16.3% linkers on the basis of both 220-nm absorbance and amino acid analysis (Ownby, D. W., Zhu, H., Schneider, K., Beavis, R. C., Chait, B. C., and Riggs, A. F. (1993) J. Biol. Chem. 268, 13539-13547). The subunit proportions have now been redetermined by SDS capillary electrophoresis as a test of the HPLC results. The electrophoresis, monitored at 214 nm, avoided the use of Coomassie Blue and provided results identical with those obtained by HPLC. Capillary electrophoresis monitored at both 214 and 415 nm was used to show that linker chains do not bind heme. Heme content has been found to be 2.9% by determination of hemin, amino acid analysis and dry weight. Measurement of the rate of hemin loss from oxidized L. terrestris Hb shows that high rates of loss can account for values of heme content significantly below 2.9% (or 0.26% iron).

Generation of CD1+RelB+ dendritic cells and tartrate-resistant acid phosphatase-positive osteoclast-like multinucleated giant cells from human monocytes

We previously showed that granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF) stimulate the differentiation of human monocytes into two phenotypically distinct types of macrophages. However, in vivo, not only CSF but also many other cytokines are produced under various conditions. Those cytokines may modulate the differentiation of monocytes by CSFs. In the present study, we showed that CD14+ adherent human monocytes can differentiate into CD1+relB+ dendritic cells (DC) by the combination of GM-CSF plus interleukin-4 (IL-4) and that they differentiate into tartrate-resistant acid phosphatase (TRAP)-positive osteoclast-like multinucleated giant cells (MGC) by the combination of M-CSF plus IL-4. However, the monocyte-derived DC were not terminally differentiated cells; they could still convert to macrophages in response to M-CSF. Tumor necrosis factor-alpha (TNF-alpha) stimulated the terminal differentiation of the DC by downregulating the expression of the M-CSF receptor, cfms mRNA, and aborting the potential to convert to macrophages. In contrast to IL-4, interferon-gamma (IFN-gamma) had no demonstrable effect on the differentiation of monocytes. Rather, IFN-gamma antagonized the effect of IL-4 and suppressed the DC and MGC formation induced by GM-CSF + IL-4 and M-CSF + IL-4, respectively. Taken together, these results provide a new aspect to our knowledge of monocyte differentiation and provide evidence that human monocytes are flexible in their differentiation potential and are precursors not only of macrophages but also of CD1+relB+DC and TRAP-positive MGC. Such a diverse pathway of monocyte differentiation may constitute one of the basic mechanisms of immune regulation.

[Landau-Kleffner syndrome: relationship between aphasia and electroencepharographic changes]

The relationship between aphasia and electroencephalogram (EEG) findings was studied in 2 patients with Landau-Kleffner syndrome. The appearance of diffuse spike and wave complexes almost always preceded the exacerbation of aphasia. Prior to the improvement of aphasia, EEG abnormality localized into the temporal region, and subsequently disappeared.

Purification and some properties of an endo-1,4-beta-D-mannanase from a marine mollusc, Littorina brevicula

An endo-1,4-beta-D-mannanase (EC 3.2.1.78) was purified from viscera of a marine mollusc Littorina brevicula. The purified enzyme, with a molecular weight of 42,000, was homogeneous by SDS-PAGE. The amino-terminal sequence starting with Gly was analyzed up to the 30th amino acid. The enzyme was stable from pH about 4.0 to about 9.0 and had its maximum activity at pH about 6.5. The purified enzyme produced M2, M3, M4, and M5 from Codium beta-1,4-mannan. The enzyme activity was greatly inhibited by Ag+, HG2+, Cu2+, and N-bromosuccinimide at 1 mM concentration.

Expression of tumor necrosis factor receptors in human lung cancer cells and normal lung tissues

The purpose of this study was to investigate the expression of tumor necrosis factor (TNF) receptors for the control of the biologic action of TNF-alpha in lung cancer cells and normal lung tissues. Lung cancer specimens and normal lung tissues were freshly obtained in pairs from 15 patients who underwent surgery for lung cancer. Thirteen lung cancer specimens expressed the 55 kDa TNF receptor messenger RNA (mRNA), whereas only six lung cancer specimens expressed the 75 kDa TNF receptor mRNA by Northern blot analysis. The 55 kDa and 75 kDa TNF receptors mRNA were detected in all and 11 normal lung tissues, respectively. All four lung carcinoma cell lines examined expressed the 55 kDa TNF receptor mRNA, but only RERF-LC-MS (MS) expressed both the 55 kDa and 75 kDa TNF receptors mRNA. Immunohistochemical examination revealed that lung cancer cells expressed the 55 kDa TNF receptor, but not the 75 kDa TNF receptor at the protein level. In normal lung tissues, the 55 kDa TNF receptor was detected in alveolar macrophages, bronchioles, and some small vessels. The 75 kDa TNF receptor was detected in alveolar macrophages. All four lung carcinoma cell lines examined exhibited the only 55 kDa TNF receptor. TNF-mediated tumor cell lysis was observed in all lung carcinoma cell lines that exhibited the 55 kDa TNF receptor except A549, which is a TNF-insensitive cell line. In surface binding assays, specific surface binding of TNF-alpha to TNF-insensitive cell line A549 was observed to be about half that of TNF-sensitive cell lines. We demonstrated the expression of two distinct TNF receptors in human lung cancer and normal lung tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

A new mutant rat with hyperbilirubinuria (hyb)

We have discovered mutant rats with hyperbilirubinuria at the laboratories of Eisai Co., Ltd., Gifu, Japan, and established a new inbred mutant strain, which was designated Eisai Hyperbilirubinuria Rat (EHBR/Eis). They show jaundice immediately after birth, and direct or conjugated hyperbilirubinemia throughout their life. The phenotypes are controlled by a single autosomal recessive gene, hyb with full penetrance. Affected homozygous males seem to have full reproductive capacity. On the other hand, the litter size of hyb/hyb females is significantly reduced at second parturition compared with that at first one. In order to maintain the strain efficiently and to produce both affected (hyb/hyb) and normal control (hyb/+) offspring at the same time, we have mainly been mating hyb/hyb males with hyb/+ females in establishing the inbred strain. We also report here the allele distribution of the EHBR/Eis strain.

A new mutant rat with turning behavior (Tur)

A new rat mutant with abnormal behavior has been found in a closed colony of Slc: SD. The affected rats turned around after their own tails beginning 4-5 weeks after birth, in response to extroceptive stimuli, such as sound or vibration. The behavior was more pronounced in younger animals. On gross observation, no alteration was found in the cerebrum, cerebellum, or anterior, posterior, or lateral semicircular canals. Light microscopic examination revealed no abnormality in the cerebrum or cerebellum. The trait was controlled by an autosomal dominant gene with incomplete penetrance (78.0%) when transferred to the WKY genetic strain background. It was named "turning" with the gene symbol Tur. A congenic strain was established, which was designated WKY/Eis-Tur.

[Hemichorea-hemiballism associated with nonketotic hyperglycemia and presenting with unilateral hyperintensity of the putamen on MRI T1-weighted images--a case report]

A 74-year-old man was admitted to our hospital with abrupt onset of hemichorea-hemiballism in the left arm and leg. On admission, the blood glucose level was 296 mg/dl, glycosylated hemoglobin Alc was 17.0%, and the serum osmolality was 296 mOsm/l. Urinalysis was negative for ketone bodies, but was strongly positive for glucose. After normalization of the blood glucose level, ballistic movement disappeared, but choreiform movement of the left arm and leg continued for 10 months. Brain CT showed a slight high density of the right putamen, which disappeared on 37th day after the onset. MRI showed high intensity on T1-weighted images and low intensity on T2-weighted images in the right putamen, which disappeared 10 months after the onset. SPECT on the 21th day after the onset showed hyperperfusion in the right putamen. 4 months later, the blood flow slightly reduced in the right putamen. The abnormality in the right putamen was considered to be the cause of his involuntary movements. High intensity in the putamen on T1-weighted MR images in the present case are presumed to have developed following mild ischemia and the reversible deposition of calcium or other material which occurred in association with nonketotic hyperglycemia.

TAN-1323 C and D, new concanamycin-group antibiotics; detection of the angiostatic activity with a wide range of macrolide antibiotics

We detected potent angiostatic activity in a MeOH extract from the mycelia of microbial strain S-45628 in the chick chorioallantoic membrane (CAM) assay. The producer was taxonomically characterized as Streptomyces purpurascens. Active principles designated TAN-1323 A-D were isolated and determined to be 18-membered macrolide antibiotics; components C and D are new members of this group, while components A and B are identical to concanamycins C and A, respectively. When tested in the CAM assay, components B and D gave huge avascular zones at the extremely low doses of 10-100 ng/disk, although components A and C showed far weaker activity due to their preferential tissue-damaging effect on the CAM. The discovery that these 18-membered macrolide antibiotics are angiostatic substances prompted us to examine other types of macrolide antibiotics, leading to the discovery that 16-membered macrolide antibiotics such as bafilomycin C1, tylosin and leucomycin also show angiostatic activity on the CAM. Thus, angiostatic potential is widely distributed among macrolide antibiotics. The mechanism of action of these macrolide antibiotics is also discussed.

[Establishment of hyperbilirubinuria rat mutant--a new animal model for jaundice]

A new animal model for jaundice, a hyperbilirubinemic rat mutant (EHBR, Eizai hyperbilirubinuria rat), was established from Sprague-Dawley rats. Hyperbilirubinemia was inherited as an autosomal recessive trait. The gene manifesting jaundice was named "hyb". Homozygotes developed jaundice immediately after birth, and a high bilirubin concentration was detected in plasma and urine. The plasma bilirubin levels were high in the neonatal period, but they decreased from 6 to 10 weeks old. In male homozygotes, plasma bilirubin levels increased rapidly until about 40 weeks, and decreased thereafter. Female homozygotes showed slightly high plasma bilirubin levels until 56 weeks, then increased rapidly thereafter. At 72 weeks, the plasma bilirubin level of females was comparable to that of males. About 80 percent of the plasma bilirubin was conjugated. Plasma biochemistry demonstrated the increase of total cholesterol and total bile acid in the homozygotes. Histopathologically, the homozygote was characterized by brown pigment in the hepatocytes, and glomerular lesions with mesangial expansion. From these findings it was considered that EHBR might be a useful animal model for studying constitutional conjugated hyperbilirubinemia and bilirubin metabolism.

A case of a primary hepatic tumor causing segmental changes on imaging and its relation to Zahn's infarct

A 69-year-old female was admitted to our hospital for further examination of an intrahepatic mass which had been found while undergoing a complete physical examination. The mass measured 4 cm in size and was located in the medial segment (S4) of the liver. On computed tomography (CT), S4 was observed to be 'atrophied' and was well enhanced segmentally. A celiac angiogram showed segmental staining, and a transarterial portogram demonstrated portal stoppage of S4 from the left branch. However, no segmental intensity difference was seen on magnetic resonance imaging (MRI). An aspiration biopsy showed adenocarcinoma and thus an operation was performed under a tentative diagnosis of intrahepatic cholangiocarcinoma. The postoperative diagnosis of the tumor was combined hepatocellular and cholangiocellular carcinoma. However, no histological abnormality was seen in S4, contrary to the expectation of Zahn's infarct. In this study, we discuss the mechanism and imaging findings of Zahn's infarct, the possible reasons as to why no pathological change was seen in S4, as well as stress the rarity of reports on Zahn's infarct in cases of portal thrombus due to hepatocellular carcinoma.

[Adult case of aortopulmonary window with aortic regurgitation: a case report]

A 45-year-old woman was admitted to our hospital because of the evaluation of heart murmur. Her height was 152 cm and body weight was 46 kg. The physical examination showed a grade 4 continuous murmur widely audible on the anterior chest wall. The chest X-ray film was normal. The electrocardiogram showed premature ventricular contractions and left ventricular (LV) hypertrophy. The two dimensional echocardiogram demonstrated the presence of moderate aortic regurgitation (AR), however, aortopulmonary window could not be detected. The aortic valve showed neither atherosclerotic nor rheumatic changes. At cardiac catheterization, pulmonary artery (PA) pressure was 20/11 mmHg and aortic pressure was 133/60 mmHg, and a step-up of O2 saturation between right ventricule and pulmonary artery (PA) was demonstrated. The aortography revealed an aortopulmonary window between the proximal ascending aorta and the main PA, and grade 2 AR. The pulmonary to systemic flow ratio averaged 1.5:1. The coronary artery and the LV wall motion was normal. Aortopulmonary window is a very rare anomaly and often requires operation in childhood because of its large left-to-right shunt in most cases. Neither an asymptomatic adult case with this anomaly nor a case with AR has not been reported so far.

TAN-1120, a new anthracycline with potent angiostatic activity

A potent angiogenesis-inhibitory compound TAN-1120 was found to be produced by a Streptomyces species isolated from a soil sample. The producing organism was characterized as a new subspecies of S. triangulatus and named S. triangulatus subsp. angiostaticus subsp. nov. due to its specific ability to produce the compound. This substance was isolated as a red powder by a combination of organic solvent extraction, silica gel column chromatography and preparative HPLC using an ODS column. Its structure was elucidated by chemical reactions and spectral analyses to be a new baumycin-group anthracycline. Reduction of TAN-1120 gave two compounds, a deoxy derivative and baumycin A1. TAN-1120 showed remarkably potent angiostatic activity in two conventional angiogenesis assay systems in vivo, while doxorubicin and daunomycin had far weaker activity. It strongly inhibited proliferation of vascular endothelial cells did not prevent capillary cord formation in vitro by the endothelial cells on extracellular matrix-coated plates. TAN-1120 is one of the most potent angiostatic agents reported.

Monoamine metabolism in the cerebrospinal fluid in Parkinson's disease: relationship to clinical symptoms and subsequent therapeutic outcomes

We correlated monoamine concentrations in the cerebrospinal fluid from de novo (untreated) patients with Parkinson's disease with their clinical symptoms and therapeutic outcome after two years of L-dopa with/without other anti-parkinson medication. A significant correlation was found between the severity of some parkinsonian symptoms and the reduction in particular monoamines: Hoehn and Yahr's stage with dopamine, norepinephrine, and homovanillic acid: rigidity with dopamine; akinesia with dopamine and norepinephrine; freezing of gait with norepinephrine; and dementia with dopamine and homovanillic acid. Tremor had no correlations with the concentrations of the monoamines measured. Patients with dementia had a significantly increased level of epinephrine concentrations. Insufficient therapeutic responses of individual symptoms were associated with significantly decreased concentrations of particular monoamines before treatment: Hoehn and Yahr's stage with norepinephrine and epinephrine; akinesia with homovanillic acid and 5-hydroxyindoleacetic acid; and freezing of gait with dopamine, norepinephrine, homovanillic acid, and 5-hydroxyindoleacetic acid. These results suggest a significant correlation between the reduction in particular monoamines and the severity of some parkinsonian symptoms and their subsequent responses to L-dopa.

Purification and properties of carbonyl reductase from rabbit kidney

An enzyme catalyzing the metabolic reduction of acetohexamide, an oral antidiabetic drug, has been purified from the cytosolic fraction of rabbit kidney to apparent homogeneity by various chromatographic techniques. The purified enzyme consists of a single polypeptide chain with a molecular weight of 28,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme requires NADPH as a cofactor and has an optimal pH of 6.0. A variety of xenobiotic carbonyl compounds including acetohexamide are effectively reduced by the enzyme. Flavonoids (quercetin and quercitrin) are potent inhibitors for the enzyme, but pyrazole or barbiturates have little effect on the enzyme activity. These findings clearly indicate that the enzyme can be classified as one of the carbonyl reductases. The enzyme also shows both prostaglandin 9-ketoreductase and 3 alpha-hydroxysteroid dehydrogenase activities. Judging from the Kcat/Km values of the enzyme for 4-pyridylketones with a straight-chain alkyl group, a hydrophobic pocket that binds most strongly to a straight-chain alkyl group of five carbon atoms in length appears to be located in the substrate-binding region of the enzyme.

Ferrocins, new iron-containing peptide antibiotics produced by bacteria. Taxonomy, fermentation and biological activity

A Gram-negative bacterium was found to produce new iron-containing peptide antibiotics, ferrocins A, B, C and D, and the producing bacterium was characterized and identified as Pseudomonas fluorescens YK-310. These new antibiotics showed antibacterial activity against Gram-negative bacteria in vitro. Although the ferrocins showed similar antibacterial activity against both Escherichia coli and Pseudomonas aeruginosa on the standard assay media, they showed strong therapeutic effects selectively against P. aeruginosa in experimentally infected mice.