Activated peritoneal macrophages inhibit the proliferation of rat ascites hepatoma AH-130 cells via the production of tumor necrosis factor-alpha and nitric oxide

OBJECTIVE

To study the effect of peritoneal macrophages on tumor cell proliferation, we cultured ascites hepatoma AH-130 cells with unstimulated, or lipopolysaccharide (LPS)- or interleukin (IL)-2-stimulated rat peritoneal macrophages, and examined the proliferation of AH-130 cells.

MATERIALS AND METHODS

Rat peritoneal macrophages isolated from male Wistar rats were co-cultured with AH-130 cells in the absence or presence of LPS or IL-2. After incubation, proliferation of AH-130 cells was analyzed using flow cytometry. In addition, the levels of tumor necrosis factor (TNF)-alpha and nitric oxide (NOx, nitrate + nitrite) in the culture supernatants were measured. Furthermore, anti-TNF-alpha antibody (10 microg/ml) and nitric oxide synthase inhibitor, N(G)-monomethyl-L-arginine (L-NMMA, 100 microM) were added to the coculture, and their effect on AH-130 cell proliferation was examined.

RESULTS

When AH-130 cells were co-cultured with unstimulated peritoneal macrophages, proliferation of AH-130 cells was not affected. In contrast, when AH-130 cells were cocultured with peritoneal macrophages in the presence of LPS (0.1-20 microg/ml) or IL-2 (1-200 U/ml), proliferation of AH130 cells was dose-dependently suppressed by LPS or IL-2. Moreover, LPS- or IL-2-stimulation increased the levels of TNF-alpha and NOx in the supernatants of AH-130 cell and macrophage co-culture, although LPS and IL-2 did not induce TNF-alpha and NOx production by AH-130 cells incubated without macrophages. Interestingly, anti-TNF-alpha antibody and L-NMMA significantly inhibited the suppression of AH-130 cell proliferation by LPS- or IL-2-stimulated macrophages (p < 0.05). Furthermore, exogenously added recombinant rat TNF-alpha (0.26-1300 ng/ml) or NO donor (GSNO, S-nitroso-L-glutathione) (0.1 - 10 mM) dose-dependently suppressed the proliferation of AH-130 cells in the absence of macrophages.

CONCLUSION

Together these observations suggest that when peritoneal macrophages are activated by LPS and IL-2, they suppress the proliferation of ascites hepatoma AH-130 cells via the production of TNF-alpha and nitric oxide.

Biological activities of novel lipid mediator sphingosine 1-phosphate in rat hepatic stellate cells

Sphingosine 1-phosphate (S-1-P), a lipid mediator shown to be a ligand for aortic G protein-coupled receptor [corrected] (AGRs), endothelial differentiation gene (EDG)1, EDG3, and AGR16/EDG5, is stored in platelets and released on their activation. Platelet consumption occurs in acute liver injury. Hepatic stellate cells (HSCs) play an important role in wound healing. Effects of S-1-P on HSCs were investigated. S-1-P enhanced proliferation of culture-activated HSCs. The mitogenic effect was pertussis toxin sensitive, mitogen-activated protein kinase dependent, and more prominent at lower cell density. S-1-P increased contraction of collagen lattices containing HSCs, irrespective of activation state, in a C3 exotoxin-sensitive manner. mRNAs of EDG1 and AGR16, but not of EDG3, were detected in HSCs. In HSC activation, EDG1 mRNA levels were downregulated, whereas AGR16 mRNA levels were unchanged. Considering that HSCs are capable of production of extracellular matrices and modulation of blood flow in sinusoids, our results suggest that S-1-P may play a role in wound healing process in the liver.

Presence and quantification of neuropeptide Y in pulmonary edema fluids in rats

The present study was undertaken to determine the contribution of neuropeptide Y to edema occurrence in neurogenic and hydrostatic pulmonary edema. To induce neurogenic pulmonary edema, fibrinogen and thrombin were injected into the cisterna magna; and to evoke hydrostatic pulmonary edema, saline was infused intravenously. Concentrations of neuropeptide Y in serum and edema fluid were measured using enzyme-linked immunosorbent assay (ELISA), which showed a mean value of 158 nM (95% confidence limit 124-202 nM) in the neurogenic edema fluid, significantly higher than that in the hydrostatic one. Using immunohistochemistry, fluorescent signals reactive to neuropeptide Y were found in the alveolar macrophages and edema fluid in case of fibrin-induced pulmonary edema, but were almost absent in hydrostatic edema and absent in normal lungs. Mean ratio of protein concentrations in edema fluid to that in serum was 74.9 +/- 0.9% in fibrin-induced pulmonary edema, being higher than that in hydrostatic one. From these results, we conclude that neuropeptide Y has a relationship to the high protein concentration ratio, i.e., to increased pulmonary vascular permeability, and consequently may contribute to the development of neurogenic pulmonary edema in rats.

Spectroscopic characterization of the conformational adaptability of Bombyx mori apolipophorin III

Apolipophorin III (apoLp-III) from the silkmoth, Bombyx mori, has been over-expressed in Escherichia coli, purified and characterized. Far-UV CD spectroscopic analysis revealed 65% alpha-helix secondary structure. Near-UV CD spectra obtained in buffer or complexed with dimyristoylglycerophosphocholine (DMPC), provided evidence that apoLp-III alpha-helices reorient upon interaction with lipid, indicative of a protein conformational change. In guanidine hydrochloride (GdnHCl) denaturation studies, a transition midpoint of 0.33 M was observed, corresponding to a DeltaGDH2O = 2.46 kcal. mol-1. Fluorescence studies of the sole tryptophan residue (Trp40) in apoLp-III revealed an emission lambdamax = 327 nm. Compared to free tryptophan, Stern-Volmer constants (KSV) for acrylamide and KI quenching of Trp40 fluorescence were decreased by 20-fold and sevenfold, respectively. In studies of apoLp-III-DMPC disc complexes, far-UV CD spectroscopy revealed an increase in alpha-helix content to approximately 85% and a ninefold increase in the GdnHCl-induced denaturation transition midpoint to 3 M. In studies of lipid interaction, apoLp-III was shown to disrupt both negatively charged and zwitterionic phospholipid bilayer vesicles, transforming them into discoidal complexes. Characterization of apoLp-III-DMPC discs, using 5-doxyl or 12-doxyl stearic acid as lipid-based quenching agents, revealed that Trp40 localizes near the phospholipid polar head groups. KSV values for acrylamide and KI quenching of intrinsic fluorescence of apoLp-III-DMPC discs indicate that Trp40 is embedded in the lipid milieu, with little or no accessibility to the aqueous quenchers. Given the large amount of alpha-helix in apoLp-III, the data presented support a model in which amphipathic alpha-helical segments are stabilized by helix-helix interactions and lipid association induces a protein conformational change which results in substitution of helix-helix interactions for helix-lipid contacts.

cDNA and deduced amino acid sequences of apolipophorin-IIIs from Bombyx mori and Bombyx mandarina

The cDNA sequence for apolipophorin-III from two strains of Bombyx mori (N4 and P50) and the Japanese and Chinese strains of Bombyx mandarina were determined. Both the cDNA and deduced amino acid sequences of the four apolipophorin-IIIs were highly similar (95-98%). The four Bombyx sequences also showed significant similarity to the sequence of apolipophorin-III from another lepidopteran, Manduca sexta (83-84%), particularly in the five amphipathic alpha-helices that are proposed to play a critical role in the binding of apolipophorin-III to lipophorin. In the coding region, the nucleotide sequences for the Chinese strain of B. mandarina and the P50 strain of B. mori were identical, supporting the suggestion that P50 is the current strain most closely related to the original domesticated strain. The N4 strain of B. mori is more closely related to these two strains than is the Japanese strain of B. mandarina, suggesting that Japanese strain of B. mandarina separated from the Chinese strain of B. mandarina before domestication of B. mori. Arch.

[Participation of neuropeptide Y Y3-receptor subtype in the increase in lung vascular permeability--for therapy of respiratory failure]

In order to find some treatments for respiratory failure caused by pulmonary edema, we investigated the mechanism of neurogenic pulmonary edema. Previously, stimulation of sympathetic nerves caused an increase in pulmonary vascular permeability, possibly due to neuropeptide Y. Neuropeptide Y injected into the trachea increased lung vascular permeability dose-dependently, the ED50 of which was 0.3-1 nM. Such an effect remained even after treatment with reserpine, as well as in the presence of alpha- and beta-blockers. And norepinephrine enhanced the effect of neuropeptide Y on lung vascular permeability. These responses were almost similar to those obtained by stimulation of sympathetic nerves. Furthermore, neuropeptide Y, in fibrin-induced pulmonary edema, was localized in alveolar macrophages and alveolar spaces, amounting to approximately 200 nM in edema fluid. The value was significantly greater than that obtained in hydrostatic pulmonary edema by 10-30 times. Peptide YY, an analogue of neuropeptide Y, had no action on lung vascular permeability, whereas the effect of neuropeptide Y was inhibited by pretreatment with neuropeptide Y- 13-36, an antagonist for Y3-recetor subtype. These results suggested that neuropeptide Y enhances the lung vascular permeability via Y3-recetor subtype. Neuropeptide Y- 13-36, in fibrin-induced pulmonary edema, decreased a ratio of protein concentration in edema fluid to that in serum, indicating that neuropeptide Y actually acts a role in the development of neurogenic pulmonary edema, via an increase in lung vascular permeability.

Structure and function of fibrinogen: insights from dysfibrinogens

The structure-function relationships of dysfibrinogens and their clinical implications are discussed on the basis of the data provided from representative molecules.

A novel tripartite structure comprising a mariner-like element and two additional retrotransposons found in the Bombyx mori genome

A clone of a DNA-mediated mobile element (transposon) corresponding to a mariner-like element (MLE) was obtained by carrying out the polymerase chain reaction with genomic DNA of Bombyx mori using a Hyalophora cecropia MLE sequence as a primer. This clone had a size of about 4.2 kb and, after sequencing, was found to contain an RNA-mediated, shorter retrotransposon named L1Bm, which was in turn integrated with a much longer retrotransposon named BMC1. Thus, the mobile elements made a novel tripartite structure. The BMC1 and L1Bm moieties of the composite structure each contained a 63-bp conserved sequence which was subsequently found to be highly conserved in all BMC1 and L1Bm elements registered so far. We propose that the 63-bp stretch may be a recognition site for a retrotransposition mechanism conducted by a reverse transcriptase and an endonuclease complex. On the basis of this inference, we propose a model that predicts how different types of BMC1 and L1Bm elements are dispersed in the genome. In addition, a phylogenetic tree made from the current and extant BMC1 and L1Bm sequences indicated that these elements can be classified into Subfamilies I and II.

A case of fibrous histiocytoma of the liver

Malignant fibrous histiocytoma (MFH) is a rare disease. We describe a 68-year-old man admitted to the hospital because of malaise. On admission, hematologic and serum chemical examinations showed no abnormalities. A tumor measuring 6.0 x 6.0 x 5.5 cm was found in segment S6 of the right lobe of the liver. A computed tomographic scan of the abdomen revealed a mass surrounded by a capsule-like region with a nonuniform shadow at its margin. The mass contained a nonuniform low density area. A magnetic resonance imaging scan showed low intensity on T1-weighted images and high intensity on T2-weighted images. An angiogram of the abdomen revealed a tumor with a darkly stained margin during the venous phase. Partial resection of the liver, including S6 and part of S7, was performed. On histopathological examination, this case was characterized by a storiform pattern. The inside of the tumor showed a storiform-pleomorphic pattern with inflammatory cell infiltration and partial mucinous degeneration. On immunohistochemical studies, the tumor cells stained positively for CD6. The diagnosis was MFH.

Thiazolidinediones suppress endothelin-1 secretion from bovine vascular endothelial cells: a new possible role of PPARgamma on vascular endothelial function

We examined the effect of troglitazone on immunoreactive endothelin-1 (ET-1) secretion from cultured bovine vascular endothelial cells (bVECs). Insulin (10(-9)-10(-7) M) stimulated ET-1 secretion in a dose-dependent fashion without any kinetic change. Troglitazone (1-20 microM) dose-dependently inhibited both spontaneous and insulin-stimulated ET-1 secretion. This inhibitory effect of troglitazone was associated with reduced ET-1 mRNA levels. Addition of indomethacin (100 microM) or Nw-nitro-l-arginine methyl ester (1 mM) and downregulation of protein kinase C by prolonged pretreatment of the cells with a phorbol ester, 12-O-tetradecanoylphorbol 13-acetate, did not affect the inhibitory effect of troglitazone at concentrations up to 10 microM. Troglitazone did not change the intracellular Ca2+ concentration stimulated by angiotensin II (10 microM). Other PPARgamma ligands, pioglitazone (1-10 microM) and 15-deoxy-delta 12, 14-prostaglandin J2 (1-10 microM), but not a PPARalpha ligand, bezafibrate (1-10 microM), dose-dependently suppressed spontaneous ET-1 secretion from bVECs. These results, taken together, suggest that troglitazone inhibits ET-1 mRNA expression and secretion in bVECs possibly through activation of PPARgamma. This inhibition may contribute to the hypotensive effect of troglitazone in insulin-resistant subjects.

Lipid transfer particle catalyzes transfer of carotenoids between lipophorins of Bombyx mori

The yellow color of Bombyx mori hemolymph is due to the presence of carotenoids, which are primarily associated with lipophorin particles. Carotenoids were extracted from high density lipophorin (HDLp) of B. mori and analyzed by HPLC. HDLp contained 33 micrograms of carotenoids per mg protein. Over 90% of carotenoids were lutein while alpha-carotene and beta-carotene were minor components. When larval hemolymph was subjected to density gradient ultracentrifugation, a second minor yellow band was present, which was identified as B. mori lipid transfer particle (LTP). During other life stages examined however, this second band was not visible. To determine if coloration of LTP may fluctuate during development, we determined its concentration in hemolymph and compared it to that of lipophorin. Both proteins were present during all life stages and their concentrations gradually increased. The ratio of lipophorin: LTP was 10-15:1 during the fourth and fifth instar larval stages, and 20-30:1 during the pupal and adult stages. Thus, there was no correlation between the yellow color attributed to LTP and its hemolymph concentration. It is possible that yellow coloration of the LTP fraction corresponds to developmental stages when the particle is active in carotene transport. To determine if LTP is capable of facilitating carotene transfer, we took advantage of a white hemolymph B. mori strain which, when fed artificial diet containing a low carotene content, gives rise to a lipophorin that is nearly colorless. A spectrophotometric, carotene specific, transfer assay was developed which employed wild type, carotene-rich HDLp as donor particle and colorless low density lipophorin, derived from the white hemolymph strain animals, as acceptor particle. In incubations lacking LTP carotenes remained associated with HDLp while inclusion of LTP induced a redistribution of carotenes between the donor and acceptor in a time and concentration dependent manner. Time course studies suggested the rate of LTP-mediated carotene transfer was relatively slow, requiring up to 4 h to reach equilibrium. By contrast, studies employing 3H-diacylglycerol labeled HDLp as donor particle in lipid transfer assays revealed a rapid equilibration of label between the particles. Thus, it is plausible that the slower rate of LTP-mediated carotene transfer is due to its probable sequestration in the core of HDLp.

Biological activities of a novel lectin derived from silkworm faeces: characteristic changes of mouse peritoneal macrophages by the lectin

A novel lectin derived from silkworm faeces, named NUE, activates phagocytosis of mouse peritoneal macrophages. At this time, significant morphological changes of the cells take place. NUE-treated macrophages formed projection-like neurocytes within 12 hr of treatment, and appeared somewhat flat in shape with the activation of cell growth. Associated with the morphological changes, actin was organized in dot-like structures corresponding to cell-substratum contact sites in NUE-treated macrophages. Vinculin, a cytoskeletal protein involved in microfilament-membrane interaction, formed doughnut-like rings matching the actin-dots, called "podosomes". Furthermore, observation by interference reflection microscopy showed that NUE-treated macrophages adhered more strongly to the substratum at local areas. According to these changes, more proteins associated with cell-substratum contact sites became to detergent-resistant. It was shown that NUE changed adhesive form of mouse peritoneal macrophages structurally and qualitatively.

Activated rat stellate cells express c-met and respond to hepatocyte growth factor to enhance transforming growth factor beta1 expression and DNA synthesis

Hepatocyte growth factor (HGF) decreases transforming growth factor beta1 (TGFbeta1) levels in the liver and attenuates hepatic fibrosis caused by dimethylnitrosamine in rats. In the liver, HGF is presumed to act predominantly on parenchymal cells, and TGFbeta1 is produced mainly by mesenchymal cells. In hepatic fibrosis, stellate cells play a central role with undergoing activation, which also occurs when the cells are cultured on plastic. Thus, we wondered if HGF could act directly on stellate cells. c-Met was detected in rat stellate cells activated by culture for 10 days, but not in the cells cultured for 3 days. Specific binding of HGF to the activated cells was determined, and Scatchard analysis indicated an apparent Kd of 1.5 nM. c-Met mRNA was detected in freshly isolated stellate cells from rats treated with carbon tetrachloride for 8 weeks, but not in those cells from normal rats. These results indicate that stellate cells express c-met when activated in vitro and in vivo. HGF enhanced TGFbeta1 production and DNA synthesis in the activated cells.

The effect of turbulent fluctuation of air on thermal sensation

The palm of right hand was alternately exposed to turbulent and laminar flows of air with the same velocity, to investigate the effect of turbulent velocity fluctuation on thermal sensation. It could be quantitatively shown for the first time, by measuring subjective sensations, that the turbulent velocity fluctuation had the effect of causing the air temperature to be felt lower than that of the laminar flow. The results of heat transfer experiments using an aluminum disk as a model of the palm suggested that the difference in thermal sensation for the two air flows was generally ascribable to the difference in heat transfer coefficient from the skin of the palm caused by the turbulent velocity fluctuation. The hypothesis that the temperatures of the turbulent and laminar flows of air with the same velocity would be felt the same when heat losses from the skin to the two air flows were equal, was supported by the results of these experiments.

Preliminary study on the effect of rocking on activities of persons with severe mental and physical handicaps

In this preliminary observation, a group of seven mentally and physically handicapped persons of chronological ages ranging from 15.4 yr. to 26.8 yr. experienced 15 sec. of physical rocking. For the further analysis, the poststimulus periods were classified into either those when the subjects' spontaneous head, mouth, and body movements had increased from the prestimulus period or those decreased. The median heart rates recorded in the poststimulus period were not significantly different from those in the prestimulus period on trials on which there was an observable increase in the rates of spontaneous head, mouth, and body movements; however, the median heart rates decreased during those trials on which a decrease in the rates of the movements occurred. Since it is said that rocking heightens arousal of persons with mental and physical handicaps, it is suggested that spontaneously emitted, aimless head, mouth, and body movements attributed to low arousal were reduced by heightened arousal rather than by a decline in participants' activities.

Telomere shortening in the colonic mucosa of patients with ulcerative colitis

Telomere length in human somatic cells gradually decreases with the number of cell divisions and is regarded as a marker of somatic cell turnover. Mucosal cells of the affected colon show rapid turnover in individuals with active ulcerative colitis (UC). Telomere length was determined by Southern blot analysis of terminal restriction fragments (TRFs) from the colonic mucosa of 17 patients with UC in remission, two of whom showed dysplasia, and 17 control subjects without colitis. For each individual, mean TRF length was compared between rectal mucosa and unaffected cecal mucosa. The mean TRF length of the rectal mucosa was significantly less than that of cecal mucosa in UC patients (7.87 +/- 0.36kb versus 8.77 +/- 0.21 kb; P = 0.0015, Wilcoxon signed rank test), whereas no significant difference was detected in the control subjects. The extent of telomere shortening was 10.6 +/- 3.35% in UC patients, compared with 0.8 +/- 0.64% in noncolitis controls (P = 0.0024, Mann-Whitney U-test). Four UC patients, two of whom had dysplasia, showed telomere shortening of more than 20% in the rectal mucosa. These observations suggest that telomere shortening in the colonic mucosa of individuals with UC may represent the history of mucosal inflammation during disease of long duration, and that it may contribute to aneuploidy in UC.

Bilateral paraduodenal hernias: computed tomography and magnetic resonance imaging appearance

Paraduodenal hernias are rare congenital malformations. We report an unusual case of bilateral paraduodenal hernias diagnosed preoperatively by small bowel series, computed tomography (CT), and magnetic resonance imaging (MRI). Both CT and MRI are useful in the noninvasive diagnosis of paraduodenal hernias.

Fission yeast Ste9, a homolog of Hct1/Cdh1 and Fizzy-related, is a novel negative regulator of cell cycle progression during G1-phase

When proliferating fission yeast cells are exposed to nitrogen starvation, they initiate conjugation and differentiate into ascospores. Cell cycle arrest in the G1-phase is one of the prerequisites for cell differentiation, because conjugation occurs only in the pre-Start G1-phase. The role of ste9(+) in the cell cycle progression was investigated. Ste9 is a WD-repeat protein that is highly homologous to Hct1/Cdh1 and Fizzy-related. The ste9 mutants were sterile because they were defective in cell cycle arrest in the G1-phase upon starvation. Sterility was partially suppressed by the mutation in cig2 that encoded the major G1/S cyclin. Although cells lacking Ste9 function grow normally, the ste9 mutation was synthetically lethal with the wee1 mutation. In the double mutants of ste9 cdc10(ts), cells arrested in G1-phase at the restrictive temperature, but the level of mitotic cyclin (Cdc13) did not decrease. In these cells, abortive mitosis occurred from the pre-Start G1-phase. Overexpression of Ste9 decreased the Cdc13 protein level and the H1-histone kinase activity. In these cells, mitosis was inhibited and an extra round of DNA replication occurred. Ste9 regulates G1 progression possibly by controlling the amount of the mitotic cyclin in the G1-phase.

Precore wild-type DNA and immune complexes persist in chronic hepatitis B after seroconversion: no association between genome conversion and seroconversion

Precore hepatitis B virus (HBV) mutants may gradually prevail during or after seroconversion (SC) from hepatitis B e antigen (HBeAg) to hepatitis B e antigen antibody (anti-HBe) status in many chronic hepatitis B (CH-B) patients. However, patients with CH-B still produce anti-HBe more than several years after SC, and the relationship between SC and genome conversion in the precore region has not been clarified. Therefore, in patients with CH-B who had a sustained loss of HBeAg and complete remission of hepatitis after SC, the precore region was sequenced in paired serum samples from 1 year before SC to 3 years after SC. Mutant precore defective HBV DNA was found in only 6 (19%) of 31 CH-B patients who had a complete remission of hepatitis after SC. Mixed-type HBV DNA (precore wild-type and mutant-type) was found in 4 (13%) patients. Wild-type HBV DNA was found in 21 (68%) CH-B patients after SC. Longer-term follow-up of 11 CH-B patients indicated that 3 of 11 patients experienced precore genome conversion 2 to 3 years after SC. E-plus DNA or e-minus DNA was semiquantitated by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) assays before and after SC. E-plus DNA levels decreased from 10(5.56+/-1.58) to 10(2.45+/-1.61). Similarly, e-minus DNA levels declined from 10(4.25+/-1.56) to 10(1.86+/-1.37). By dot-blot assay, serum HBV DNA became negative soon after SC, as did serum HBeAg. In contrast, HBeAg-containing immune complexes were still detected after SC. Anti-HBe antibody was produced throughout SC and thereafter, as determined by a sensitive experimental assay. Therefore, we conclude that genome-conversion in the precore region is a separate event from HBeAg/anti-HBe seroconversion.

The Ste16 WD-repeat protein regulates cell-cycle progression under starvation through the Rum1 protein in Schizosaccharomyces pombe

The haploid cells of the fission yeast, Schizosaccharomyces pombe, are arrested in the G1-phase by nitrogen starvation and are committed to sexual reproduction (mating and sporulation). We isolated the sterile mutants which were defective in G1 arrest following nitrogen starvation. Genetic analysis of these mutants defined a single locus designated as ste16. The nucleotide sequence revealed that ste16+ encodes an 82-kDa protein containing eight WD40-repeats in its carboxy terminal half. The ste16 disruptant was viable, but arrested the cell cycle in the G2-phase after the nutritional down-shift. When transferred to fresh growth medium, the G2-arrested ste16Delta haploids resumed the mitotic cycle from the S-phase, resulting in diploidization. This diploidization phenomenon was completely suppressed by the null mutation of rum1 encoding the inhibitor of Cdc2 kinase. As the Rum1 protein level was remarkably elevated in the ste16Delta, the Ste16 protein negatively controls the Rum1 level. The loss of function of ste16 disturbs the cell-cycle progression and impairs the mechanism for the maintenance of ploidy.

Advanced glycation endproducts stimulate mitogen-activated protein kinase and proliferation in rabbit vascular smooth muscle cells

Advanced glycation end products of bovine serum albumin (AGEs-BSA) exhibited biphasic effects on the proliferation of cultured rabbit vascular smooth muscle cells (VSMCs) in terms of [3H]thymidine incorporation and cell number count; a stimulatory effect was observed at 1-10 micrograms/ml and an inhibitory effect at more than 20 micrograms/ml, while it inhibited [3H]thymidine incorporation even at 1-10 micrograms/ml in cultured bovine vascular endothelial cells (VECs). Transient activation of p42 mitogen-activated protein kinase (MAPK) with a peak at around 5 min and a subsequent sustained phase was induced by AGEs-BSA in VSMCs, but not in VECs. The dependence of MAPK activation on AGEs-BSA dose was correlated with that of VSMCs proliferation.