Immunophenotypic and immunoelectron microscopic characterization of major constituent cells in malignant fibrous histiocytoma using human cell lines and their transplanted tumors in immunodeficient mice

BACKGROUND

Malignant fibrous histiocytoma (MFH) is the most common soft tissue sarcoma of adult life. Its histogenesis, however, is still a matter of debate because of its various cellular components.

EXPERIMENTAL DESIGN

To elucidate the nature of tumor cells of MFH, six human MFH cell lines were compared immunohistochemically and immunoelectron microscopically with fibrosarcoma and fibroblast cell lines. In vitro differentiation of tumor cells was evaluated after the treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA), IL-3, macrophage CSF, and granulocyte-macrophage CSF. Heterotransplantation of MFH tumor cells into nude mice and severe combined immunodeficient mice was performed to examine whether the tumor cells differentiate toward histiocytes or not. Gene expression of monocyte chemoattractant protein-1 in cultured tumor cells and transplanted tumors was also evaluated.

RESULTS

All MFH cell lines examined were positive for collagen type I and prolyl hydroxylase. They failed to react with most anti-myeloid mAb such as CD11c, CD14, CD15, CD33, CD35, CD45, anti-HLA-DR, and PM-2K. Several Ab, including CD13, CD32, CD68, CD71, and HAM56, were reactive with MFH cells. However, all of these Ab were also reactive with fibrosarcoma and/or fibroblastic cell lines. These data indicate that MFH cell lines possess immunophenotypic characteristics very similar to those of fibrosarcoma and fibroblastic cell lines. In vitro treatment of tumor cells with TPA, IL-3, macrophage CSF, granulocyte-macrophage CSF, or their combination did not change their immunophenotypic characteristics and did not induce differentiation toward histiocytes (macrophages). Transplantation of tumor cells into nude mice and severe combined immunodeficient mice produced tumors similar in histology to human MFH. Tumor cells in the transplanted tumors revealed the same immunophenotypic characterization that they did in vitro. No in vivo differentiation of tumor cells toward histiocytes was observed. Immunohistochemical staining with anti-mouse macrophage mAb revealed marked infiltration of macrophages of mouse origin. Quantitative immunoelectron microscopy disclosed that these cells coincided with histiocyte-like cells. Gene expression of monocyte chemoattractant protein-1 was detected in all MFH cell lines as well as in transplanted tumors.

CONCLUSIONS

The histiocyte-like cells in malignant fibrous histiocytoma are not a neoplastic component but rather infiltrated macrophages attracted by tumor-derived monocyte chemoattractant(s), and the tumor cells belong to a fibroblastic lineage differentiated from mesenchymal cells.

Adrenoleukodystrophy: the restoration of peroxisomal beta-oxidation by transfection of normal cDNA

In order to elucidate the function of ALDP [a protein encoded by the gene responsible for adrenoleukodystrophy (ALD)], normal ALDP cDNA, inserted in an expression vector driven by chicken beta-actin promotor, was transfected into ALD fibroblasts. In a transient expression system, the fatty acid composition did not change even though the ALDP was newly synthesized based on the findings of a western blot analysis. In a stable expression system, 3 cell lines were strongly positive for ALDP. In these cells the level of very long chain fatty acid (C26:0) turned out to be as low as those of the control, while the activities of C24 beta-oxidation, as checked by two different methods, became normal. From these results, it is concluded that ALDP is indispensable for the function of peroxisomal beta-oxidation, and thus the treatment of ALD may be possible by the supplementation of ALDP.

Neutrophil accumulation and activation by homologous IL-8 in rabbits. IL-8 induces destruction of cartilage and production of IL-1 and IL-1 receptor antagonist in vivo

Whether or not IL-8 attracts T lymphocytes and activates neutrophils in vivo remains unclear. Most studies on function of IL-8 in vivo have been done on human IL-8 in heterologous animals. To elucidate the role of IL-8 in vivo, we injected homologous IL-8 into rabbit knee joints and investigated the inflammatory response. Injection of 10 micrograms of rabbit IL-8 induced a massive accumulation of neutrophils. IL-8 attracts T lymphocytes in vitro; however, rabbit IL-8 induced no appreciable lymphocyte accumulation in rabbits. Although human IL-8 was reported not to induce cartilage destruction when injected into heterologous animals, we observed that rabbit IL-8 did provoke a release of neutrophil elastase, leading to cartilage destruction, when injected into rabbits. An inhibitor against neutrophil elastase (ONO-5046) prevented destruction of the cartilage. Injection of rabbit IL-8 induced bioactive and immunoreactive IL-1 beta and IL-1 receptor antagonist (IL-1Ra) in the joint cavity. Immunohistochemistry showed that IL-1 beta and IL-1Ra positive cells were infiltrating leukocytes. In neutrophil-depleted rabbits, rabbit IL-8 induced far lesser concentrations of IL-1 beta and IL-1Ra and no cartilage destruction compared with findings in normal rabbits. Thus, the infiltrating neutrophils are the main producers of these cytokines and are responsible for the cartilage destruction. In addition to neutrophil chemotactic activity, IL-8 proved to have a neutrophil-activating capability in vivo, with respect to release of neutrophil elastase and induction of IL-1 beta and IL-1Ra.

Neutrophil accumulation and activation by homologous IL-8 in rabbits. IL-8 induces destruction of cartilage and production of IL-1 and IL-1 receptor antagonist in vivo

Whether or not IL-8 attracts T lymphocytes and activates neutrophils in vivo remains unclear. Most studies on function of IL-8 in vivo have been done on human IL-8 in heterologous animals. To elucidate the role of IL-8 in vivo, we injected homologous IL-8 into rabbit knee joints and investigated the inflammatory response. Injection of 10 micrograms of rabbit IL-8 induced a massive accumulation of neutrophils. IL-8 attracts T lymphocytes in vitro; however, rabbit IL-8 induced no appreciable lymphocyte accumulation in rabbits. Although human IL-8 was reported not to induce cartilage destruction when injected into heterologous animals, we observed that rabbit IL-8 did provoke a release of neutrophil elastase, leading to cartilage destruction, when injected into rabbits. An inhibitor against neutrophil elastase (ONO-5046) prevented destruction of the cartilage. Injection of rabbit IL-8 induced bioactive and immunoreactive IL-1 beta and IL-1 receptor antagonist (IL-1Ra) in the joint cavity. Immunohistochemistry showed that IL-1 beta and IL-1Ra positive cells were infiltrating leukocytes. In neutrophil-depleted rabbits, rabbit IL-8 induced far lesser concentrations of IL-1 beta and IL-1Ra and no cartilage destruction compared with findings in normal rabbits. Thus, the infiltrating neutrophils are the main producers of these cytokines and are responsible for the cartilage destruction. In addition to neutrophil chemotactic activity, IL-8 proved to have a neutrophil-activating capability in vivo, with respect to release of neutrophil elastase and induction of IL-1 beta and IL-1Ra.

[Effects of polychlorinated biphenyls on regeneration of the peripheral nerve in rats]

The effects of polychlorinated biphenyls (PCB) on regeneration of the peripheral nerves were investigated in rats. The sciatic nerves were crushed at the mid-thigh level on the last day of 32 days of oral administration of PCB. The sciatic nerves were biopsied from the crushed regions at 1, 2, 4, 8 and 12 weeks after crushing. Myelin thickness on the axon diameter was smaller in the PCB administered group than in the control group. There was no difference between the experimental group and the control group in the density of regenerating fibers and distribution of fiber diameters in unmyelinated fibers. After 12 weeks the number of large diameter myelinated fiber densities was lower in the experimental group than in the control group. These results indicate that PCB may affect the remyelination of the regenerating nerve.

[Segmental muscular atrophy of unilateral upper limb associated with cervical disc herniation in a juvenile male]

A 25-year-old man first noticed atrophy of right upper arm at the age of 15. This symptom progressed for the following 3 years and then became stable. As he noted difficulty in elevating his right arm above the shoulder level, at the age of 25 he was admitted to our hospital. On neurological examination, he had right scapula alata, moderate atrophy and weakness of right triceps muscle. Right triceps reflex was absent. Other neurological examinations were normal. Needle electromyography revealed neurogenic patterns in the muscles of the C5-T1 segments. Cervical MRI and CT myelography revealed mild cervical disc protrusion toward the right side at the C5/6 level and atrophy of the middle and lower cervical cord on the right side, but nothing suggestive of the fexion myelopathy. The clinical manifestations of the patient resembled those of Hirayama disease, except for the distribution of the involved muscles. Since the most severely involved level of the cervical cord (C7 segment) corresponded to the level of the protruded cervical disc, it was suggested that the cervical disc herniation played an important role in the development of the myelopathy in this patient.

Expression of monocyte chemoattractant protein-1 in meningioma

Monocyte chemoattractant protein-1 (MCP-1), purified from glioma cell line (U-105MG) culture fluid, attracts monocytes but not neutrophils. Macrophage accumulation is one of the pathological features of meningioma. To investigate the mechanism of macrophage infiltration into meningioma, the expression and localization of MCP-1 in 16 cases of meningioma were studied using Northern blot analysis and immunohistochemistry. Seven of 16 meningiomas expressed MCP-1 messenger ribonucleic acid and protein, and some degree of macrophage infiltration was seen in all 16 meningiomas. There was a relationship between MCP-1 expression and the degree of macrophage infiltration; MCP-1 was strongly expressed in meningiomas with a high degree of macrophage infiltration. Sometimes the meningioma was accompanied by perifocal edema; a correlation between macrophage infiltration into brain tumors and perifocal edema has already been reported. It was found that the degree of MCP-1 expression is not correlated with the extent of perifocal edema. The authors' findings suggest that MCP-1 plays an important role in macrophage infiltration into meningioma.

Role of leucine 201 of thermostable D-amino acid aminotransferase from a thermophile, Bacillus sp. YM-1

We studied the catalytic role of leucine 201 residue of the thermostable D-amino acid aminotransferase: the residue was shown crystallographically to be in the vicinity of the active site to interact with the bound pyridoxal phosphate. We replaced the leucine 201 by alanyl or tryptophanyl residues by means of site-directed mutagenesis. The L201A and L201W mutant enzymes showed anomalous kinetic behavior in the overall reaction. The reaction rates of the L201A and L201W mutant enzymes gradually decreased with an increase in the reaction time to become practically zero at a high concentration of substrates. The mutant enzymes were also inactivated in the half reaction with D-alanine, although more slowly than in the overall reaction. The absorption spectra of the mutant enzymes in the presence of D-alanine and alpha-ketoglutarate suggest that the enzyme molecules were mostly in the pyridoxamine form under the conditions employed. These phenomena were explained by assuming two (or more) enzyme species showing kinetically different catalysis for pyridoxamine form of the mutant enzymes, and the rate of conversion from one of these pyridoxamine forms to the pyridoxal form should be very low. The leucine 201 residue probably regulates the function of cofactor during the reaction of D-amino acid aminotransferase.

[Pseudoaneurysm of saphenous vein graft after CABG]

A 69-year-old man was admitted because of angina pectoris and thoracic descending aorta aneurysm. Staged operations were planned. First, he underwent CABG (coronary artery bypass grafting) with SVGs (saphenous vein grafts) to #4 PD, #7 and #12. Aprotinin was administrated to reduce blood loss. The routine postoperative graft angiography and enhanced CT showed a pseudoaneurysm in the SVG to #4 PD. We planned an elective operation of pseudoaneurysm repair and graft replacement of thoracic descending aorta. Also in this second operation, continuous infusion of aprotinin was started after the induction of anesthesia. About 30 minutes later, he suddenly fell in shock and cardiac arrest. Partial cardiopulmonary bypass was established and median sternotomy was performed. In the mediastinum, no bleeding was found. We found out a bleeding point of the SVG to #4 PD and a hemostatic clip on the right ventricule, and closed the bleeding point with suture. The cause of the pseudoaneurysm seemed to be defluxion of the hemostatic clip for a side brunch of the SVG. The cause of the preoperative shock may be an anaphylaxis to readministrated aprotinin.

Prevalence of senile dementia in Okinawa, Japan. COSEPO Group. Study Group of Epidemiology for Psychiatry in Okinawa

METHODS. The prevalence of dementia was investigated in Okinawa Prefecture, Japan. In all, 3524 subjects, > or = 65 years old, were sampled randomly (urban and rural populations 61.1% and 38.9% respectively). Phase 1 of the survey was carried out by specially trained students of the Faculty of Medicine who used the Mini-Mental State (MMS) scale (interview rate: 94.3%) to screen 522 (15.8%) of the 3312 subjects for the phase 2 survey. Phase 2, conducted by psychiatrists using the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) criteria, detected 172 cases of dementia. RESULTS. The estimated prevalence of dementia was 6.7%. For women, the rate increased sharply in the 90-99 year old group, and was 41.4%; for men in the 90-99 year old group prevalence was 21.2%. The ratio of Alzheimer-type dementia to multi-infarct dementia was 1.5:1 (men 1.2:1, women 1.7:1). The breakdown of the severity of dementia in the total cases was: mild 16.9%, moderate 30.8%, and severe 52.3%. The number of severe cases increased with age.

Mortality in psychiatric patients, with a specific focus on cancer mortality associated with schizophrenia

BACKGROUND

Higher mortality rates among psychiatric patients compared with the general population have been widely reported. On the other hand, lower cancer mortality for schizophrenics has been occasionally pointed out. Few studies from Japan have investigated mortality among psychiatric patients, and this study is the first large-scale follow-up in this country.

METHODS

A total of 4980 patients admitted to a national mental hospital from 1948 through 1982 were followed up until 31 August 1985. The standardized mortality ratios (SMR) were calculated in comparison to the general population, using the person-years method.

RESULTS

The SMR for total deaths and those for malignancy were as follows for males/females respectively: 2.55/3.02 and 0.84/1.37 for schizophrenia, 1.76/2.37 and 1.44/2.10 for depression, 2.45/3.04 and 1.18/1.82 for mania, 1.81/1.90 and 0.27/1.07 for neurosis, 5.55/4.33 and 1.85/3.34 for alcohol/drug abuse, and 3.65/3.57 and 1.01/0.72 for organic brain syndrome.

CONCLUSIONS

The SMR for total deaths were significantly elevated in schizophrenia, depression, mania, neurosis, alcohol/drug abuse, and organic brain syndrome, respectively. The SMR for malignancy were not elevated nor lowered significantly in any of these disease categories. The SMR for stomach cancer in male schizophrenics was significantly lower (0.27; P < 0.05).

Modulation of neutrophil influx in glomerulonephritis in the rat with anti-macrophage inflammatory protein-2 (MIP-2) antibody

The role of the chemokine, macrophage inflammatory protein-2 (MIP-2), during anti-glomerular basement membrane (GBM) antibody (Ab) glomerulonephritis (GN) was studied. Rat MIP-2 cDNA had been cloned previously. Recombinant rat MIP-2 (rMIP-2) from Escherichia coli exhibited neutrophil chemotactic activity and produced neutrophil influx when injected into the rat bladder wall. By using a riboprobe derived from the cDNA and an anti-rMIP-2 polyclonal Ab, MIP-2 was found to be induced in glomeruli with anti-GBM Ab GN as mRNA by 30 min and protein by 4 h, with both disappearing by 24 h. The expression of MIP-2 correlated with glomerular neutrophil influx. A single dose of the anti-MIP-2 Ab 30 min before anti-GBM Ab was effective in reducing neutrophil influx (40% at 4 h, P < 0.01) and periodic acid-Schiff deposits containing fibrin (54% at 24 h, P < 0.01). The anti-rMIP-2 Ab had no effect on anti-GBM Ab binding (paired-label isotope study). Functional improvement in the glomerular damage was evidenced by a reduction of abnormal proteinuria (P < 0.05). These results suggest that MIP-2 is a major neutrophil chemoattractant contributing to influx of neutrophils in Ab-induced glomerular inflammation in the rat.

In vivo effect of GroESL on the folding of glutamate racemase of Escherichia coli

The overexpression of the murI (glr) gene, which encodes the glutamate racemase of Escherichia coli, resulted in the formation of inclusion bodies of the enzyme, and little activity was found in the soluble fraction of the transformant cells. The coexpression of the groESL gene with murI caused an in vivo solubilization of glutamate racemase in an active form. We isolated the active enzyme and purified it effectively.

Different time-course production of peptidic and nonpeptidic leukotrienes and prostaglandins E2 and F2 alpha in the ovary during ovulation in gonadotropin-primed immature rats

Temporal changes in ovarian leukotrienes (LTs) and prostaglandins (PGs) were examined during ovulation to assess roles they may play in this process. Ovulation was induced in immature rats by injection with human chorionic gonadotropin (hCG; 10 IU, s.c.) 2 days after they had been primed with pregnant mare serum gonadotropin (10 IU, s.c.). The ovaries were extirpated at various intervals after hCG administration and assayed for LTB4, and LTC4/D4/E4, as well as PGE2, and PGF2 alpha. Ovarian concentration of LTB4 increased (P < 0.01) rapidly, reaching a peak at 1 hour after hCG administration, then declined (P < 0.05) by 4 hours and remained low thereafter. In contrast, LTC4/D4/E4 peaked (P < 0.01) between 1 and 2 hours, declined (P < 0.05), and then increased (P < 0.01) to achieve a second, larger peak at 10 hours. Prostaglandin E2 increased (P < 0.01) at 6 hours after hCG and did not decrease from the peak value until (P < 0.01) 14 hours after hCG. Concentrations of PGF2 alpha increased (P < 0.01) at 4 hours after hCG, but decreased (P < 0.01) from the peak by 10 hours. Although LTB4, LTC4/D4/E4, PGE2, and PGF2 alpha all increased during ovulation, the time-course differed. This suggests that each eicosanoid may play a distinct role in the process of follicular rupture.

Structure and function of beta 2-glycoprotein I: with special reference to the interaction with phospholipid

beta 2-Glycoprotein I (beta 2-GPI) is a cofactor in the recognition of a phospholipid antigen, cardiolipin, by anticardiolipin antibodies in autoimmune diseases such as systemic lupus erythematosus. We examined the interaction of various forms of bovine beta 2-GPI, such as its intact form, desialylated form (Asialo beta 2-GPI), N-terminal domain (domain I) and the modified forms of beta 2-GPI and Asialo beta 2-GPI with nicks in their C-terminal domains (domain 5), with phospholipid liposomes under different conditions of pH and ionic strength. We found that at neutral pH and low ionic strength beta 2-GPI bound to liposome membranes containing cardiolipin with a dissociation constant (Kd) of 10(-8) M. Phosphatidylglycerol, phosphatidylserine, phosphatidic acid or phosphatidylinositol bound to beta 2-GPI, but phosphatidylcholine did not. We also found that domain I and Asialo beta 2-GPI bound to cardiolipin with Kd values of 10(-6) and 10(-8) M, respectively. At neutral pH and both low and high ionic strengths, the affinities of nicked forms of beta 2-GPI and Asialo beta 2-GPI for cardiolipin were lower than those of intact forms but similar to that of domain 1.

[Small bowel metastasis from large cell carcinoma of the lung: report of a case]

The case of a 44-year-old man with metastatic tumor of the small intestine from large cell carcinoma of the lung was reported. The patient underwent exploratory thoracotomy because of tumor invasion into the left ventricle. He was discharged from our department after chemotherapy and irradiation. However, he was again admitted because of the development of anemia secondary to melena. An abdominal ultrasonography revealed ascites and tumor of the small intestine. Symptoms of ileus also developed. A laparotomy was performed. The metastatic tumors were found in the jejunum, and resection of jejunum was performed. The postoperative course of the patient was uneventful, and he survived one month after laparotomy. Small bowel metastasis of lung cancer, which is unusual pattern of metastasis, is also reviewed.

Optimum determination of speckle size to be used in electronic speckle pattern interferometry

Characteristics of the fringe pattern detected by an electronic speckle pattern interferometer, in conditions in which a test object deforms in an arbitrary direction and the speckle intensity is detected over a pixel area in the TV camera to be used, have been investigated from two aspects: speckle noise reduction and fringe contrast. The main result is that the fringes are obtained with high contrast and low speckle noise, if the speckle size is selected by the optical system so as to be smaller than the pixel size. This result is applicable to highly accurate measurements of the out-of-plane displacements of the test object, whose in-plane displacement is small.

Kinetic analysis of endocytosis and intracellular fate of liposomes in single macrophages

Endocytosis and the intracellular fate of liposomes in single mouse peritoneal macrophages were examined kinetically by fluorescence microphotometry. Liposomes labeled with N-(7-nitro-2,1,3-benzoxadiazol-4-yl)phosphatidylethanolamine or containing 8-amino-naphthalene-1,3,6-trisulfonate were promptly incorporated into macrophages on incubation at 37 degrees C, but fluorescence increase caused by hydrolysis of 4-methylumbelliferyl-beta-D-glucoside encapsulated in the liposomes was observed after 30 min of incubation. The fluorescences of calcein and 8-hydroxy-1,3,6-pyrenetrisulfonate (HPTS) in liposomes, which were respectively quenched statically due to high concentration and dynamically by a co-entrapped fluorescence quencher, p-xylene-bis-pyridinium bromide, also increased from 30 min after the start of liposome incorporation, indicating that macrophages require this period for intracellular delivery of liposomes from the cell surface to lysosomes. Measurement of the intraendosomal pH change in a single macrophage at 37 degrees C with liposomes containing a pH-sensitive fluorescent marker, HPTS, showed that the pH value decreased continuously to a constant value of 5.5 in 30-40 min after endocytosis, and this decrease was reversed on addition of NH4Cl, suggesting that acidification of endosomes is not a stepwise reaction and is coupled with delivery of liposomes. These fluorescence microphotometric systems using liposomes containing different fluorescent dyes should be useful for kinetic analyses of the endocytosis and intracellular fate of liposomes in various phagocytes.

Molecular and structural requirements of a lipoteichoic acid from Enterococcus hirae ATCC 9790 for cytokine-inducing, antitumor, and antigenic activities

Comparison was made between the immunobiological and antigenic properties of two lipoteichoic acid (LTA) fractions (LTA-1 and -2) from Enterococcus hirae ATCC 9790, their glycolipid portions, and synthetic compounds partially mimicking the above bacterial products. The more lipophilic LTA-2 fraction was capable of inducing serum tumor necrosis factor alpha and interleukin-6 in muramyldipeptide-primed mice and serum gamma interferon in those primed with Propionibacterium acnes. The LTA-2 fraction also induced tumor necrosis factor alpha, interleukin-6, and thymocyte-activating factor (essentially interleukin-1) in murine peritoneal macrophage cultures. Consecutive intravenous injections of muramyldipeptide and the LTA-2 fraction in Meth A fibrosarcoma-bearing BALB/c mice caused hemorrhagic necrosis and marked regression leading to complete regression of the tumor with no accompanying weakening or lethal effects. The LTA-2 fraction was at least 10,000-fold less pyrogenic in rabbits than a reference endotoxic lipopolysaccharide. The more hydrophilic LTA-1 fraction, on the other hand, showed at most marginal activity in the in vivo and in vitro assays. Natural glycolipids (NGL-1 and -2) which were prepared from a chloroform-methanol extract of Streptococcus pyogenes and E. hirae cells, and comparable in structure to the lipid moieties of the LTA-1 and -2 fractions, respectively, were practically inactive in all of the assays. None of the test synthetic compounds was immunobiologically active, although synthetic partial counterparts of the structure of LTA proposed by W. Fischer (Handb. Lipid Res. 6:123-234, 1990) reacted with murine monoclonal antibody TS-2, which was raised against OK-432, a penicillin-killed S. pyogenes preparation, and capable of neutralizing the cytokine-inducing activities of the LTA-2 fraction.

[Aortic valve replacement in patients older than 75 years of age]

From 1988 to 1992, 16 patients older than 75 years underwent AVR (14 cases) or AVR+MVR (two cases). All patients were followed up for an average of 2.4 years after the operation and follow-up totaled to 38 patient-years. There were no hospital death and one late death. The survival rate was 93.8% through 1 to 5 years and 15 patients are now in NYHA class I or II. The problems of AVR for elderly patients were calcification and small annulus. Decalcification using CUSA was effective technique and supraannular fixing of bioprosthetic valve avoided from aortic annular enlargement. The improved quality of life after AVR supports the aggressive surgery in elderly population.

Identification of active site lysyl residues of phenylalanine dehydrogenase by chemical modification with methyl acetyl phosphate combined with site-directed mutagenesis

A monoanionic acetylation reagent, methyl acetyl phosphate, was used to acetylate lysyl residues of the recombinant thermostable phenylalanine dehydrogenase from Thermoactinomyces intermedius. The enzyme was irreversibly inactivated with the reagent in a time- and dose-dependent manner. Simultaneous addition of substrate and coenzyme markedly protected the enzyme from inactivation. Acetylated lysyl residues presumably occurring at the active site were determined by differential modification; the enzyme was first modified with a cold reagent in the presence of both substrate and coenzyme and, after removal of the added substances by gel filtration, was then labeled with a radioactive reagent. At least 7 lysyl residues per enzyme subunit were radiolabeled by this method. To further specify the lysyl residue(s) whose modification results in inactivation of the enzyme, 5 lysyl residues highly conserved in various amino acid dehydrogenase sequences were replaced with Ala by site-directed mutagenesis. Although all of the single mutant enzymes were inactivated with the reagent as effectively as the wild-type enzyme, a double mutant enzyme in which both Lys-69 and Lys-81 were replaced with Ala was found to be inactivated very slowly. These results suggest that the reagent can acetylate both of these lysyl residues and inactivate the enzyme. Kinetic analyses of the single Lys-69 and Lys-81 mutant enzymes revealed that they are involved in substrate binding and catalysis, respectively, like the corresponding residues in the homologous leucine dehydrogenase.

Kinetics of macrophage subpopulations and expression of monocyte chemoattractant protein-1 (MCP-1) in bleomycin-induced lung injury of rats studied by a novel monoclonal antibody against rat MCP-1

We investigated the kinetics of macrophage subpopulations and the expression of monocyte chemoattractant protein 1 (MCP-1) in a rat model of bleomycin-induced lung injury. Rat macrophage subpopulations were examined by immunohistochemistry using various anti-rat macrophage monoclonal antibodies (mAbs) and their proliferative capacity by [3H]thymidine (3HTdR) autoradiography. To detect the localization of expressed MCP-1, we generated an mAb against rat MCP-1 for immunohistochemical staining. Expression of MCP-1 messenger RNA (mRNA) was detected by Northern blot hybridization. Shortly after intratracheal instillation of bleomycin, the number of exudate macrophages recognized by mAb TRPM-3 increased in the injured lungs, peaked 3 days later, and decreased thereafter, whereas tissue macrophages identified by mAb ED2 increased slowly and peaked 2 weeks after instillation. Northern blot analysis disclosed that the expression of MCP-1 mRNA in the lung was most prominent 1 day after instillation and declined thereafter, preceding the numerical change of the TRPM-3-positive exudate macrophages. Immunohistochemistry with anti-rat MCP-1 revealed that the main sources of MCP-1 production were alveolar and interstitial macrophages and polymorphonuclear leukocytes. Based on these results, MCP-1 produced by polymorphonuclear leukocytes and by alveolar and interstitial macrophages is thought to induce the infiltration of blood monocytes, and infiltrated exudate macrophages produce MCP-1 to enhance subsequent accumulation of macrophages. In contrast, the expression of MCP-1 did not correlate with the numerical changes of the ED2-positive macrophages.