Detection of lysyl oxidase gene expression in rat skin during wound healing

Lysyl oxidase (LOX) initiates the crosslinking of the lysine-derived aldehyde and plays an essential role in maturation of collagen, for example in wound healing. Although the activity of this enzyme has been examined in various disorders, and a further intriguing aspect of the relationship between LOX and tumorigenesis has recently emerged, its gene expression pattern in tissues is still unknown. We examined LOX gene expression during wound healing in rat skin. In addition, type III collagen gene expression was studied to determine the formation of fibrils. The LOX mRNA level reached a peak by day 3 after injury, which was earlier than that of type III collagen, and continued at a high level until day 22. The type III collagen mRNA level began to rise from day 3 and had increased intensely by day 22. In situ hybridization revealed grains corresponding to LOX mRNA in the fibroblasts of the granulomatous tissue. These results suggest that LOX is produced before collagen synthesis in preparation for crosslinking in the early phase of wound healing.

Effect of 1,25-dihydroxyvitamin D3 on induction of scavenger receptor and differentiation of 12-O-tetradecanoylphorbol-13-acetate-treated THP-1 human monocyte like cells

We investigated the effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on the expression of scavenger receptors in human monocytic cell line (THP-1 cells) treated for 24 h with 12-O-tetradecanoylphorbol-13-acetate (TPA) which induces their differentiation into macrophages. The capacity to degrade 125I-labeled acetyl low density lipoprotein (LDL) was developed in accordance with macrophage differentiation. The treatment with 10 nM 1,25(OH)2D3 for 72 h inhibited the degradation of acetyl LDL by THP-1 macrophages in a dose-dependent manner, suggesting that 1,25(OH)2D3 inhibits scavenging function in macrophages. In order to clarify the mechanism of its inhibitory effect on degradation of acetyl LDL, we performed the ligand binding assay using 125I-labeled acetyl LDL. Scatchard analysis revealed that 1,25(OH)2D3 decreased the number of scavenger receptors without changing the affinity for acetyl LDL. We next examined the effect of 1,25(OH)2D3 on the expression of scavenger receptor mRNA. The mRNA of type I scavenger receptor was first detected in THP-1 cells 4 days after the treatment with TPA, the mRNA level increased up to 6 days, and then decreased. The treatment with 1,25(OH)2D3 for 72 h dramatically decreased the mRNA levels after the acquisition of macrophage phenotypes as evidenced by nonspecific esterase staining. However, 1,25(OH)2D3 did not affect the activity of nonspecific esterase nor the induction of interleukin-1 beta mRNA by lipopolysaccharide in THP-1 macrophages. These findings suggest that 1,25(OH)2D3 exclusively decreases the expression of scavenger receptors in TPA-induced THP-1 macrophages without affecting the basic cellular functions as macrophages.

Regulation of apoptosis of interleukin 2-dependent mouse T-cell line by protein tyrosine phosphorylation and polyamines

We examined the effect of inhibitors of tyrosine kinase and tyrosine phosphatase on DNA fragmentation, protein tyrosine phosphorylation, and polyamine metabolism in the murine T-cell line CTLL-2. When cells were exposed to herbimycin A, a specific inhibitor of tyrosine kinase (Uehara et al., 1989, Biochem. Biophys. Res. Commun., 163:803-809), in the presence of interleukin 2 (IL-2), DNA was degraded into oligonucleosomal fragments in a dose-dependent fashion. Genistein, another inhibitor of tyrosine kinase (Akiyama et al., 1987, J. Biol. Chem., 262:5592-5596), had similar effects. Exposure of CTLL-2 cells to vanadate, a tyrosine phosphatase inhibitor, blocked with the DNA fragmentation induced by herbimycin A. Tyrosine phosphorylation of 55 Kd protein was inhibited by herbimycin A, and the inhibition was reduced by vanadate. Ornithine decarboxylase (ODC) activity decreased rapidly after herbimycin A was added to CTLL-2 cell cultures, while vanadate increased ODC activity. The exogenous addition of putrescine or spermine, but not that of spermidine, attenuated herbimycin A-induced DNA fragmentation. These findings suggest that phosphorylation of tyrosine residues of 55 Kd protein prevents DNA fragmentation and that polyamines are involved in regulation of apoptosis.

Expression of immunoreactive human hepatocyte growth factor in human esophageal squamous cell carcinomas

Hepatocyte growth factor (HGF) is a potent mitogen for epithelial cells that promotes cell motility and invasiveness. In this study, we report that the human esophageal squamous cell carcinoma (SCC) shows a significant elevation of HGF concentration (600 +/- 416 ng/100 mg protein), compared to normal mucosa (80 +/- 183 ng/100 mg protein) (P < 0.01). An association could be established between levels of HGF and decreasing differentiation of 37 SCCs. The 2-year crude survival rates were 51.1% and 68.4% at high and low HGF concentrations, respectively. The results indicate that HGF is significantly increased in human esophageal SCCs, especially of poorly differentiated type. HGF might thus be useful as a biological biomarker for characterization of human esophageal SCCs.

Long-term survival of 5 years following initial surgery for gastric cancer and simultaneous disseminated peritoneal metastasis: report of a case

We report herein the rare case of a patient who survived for 5 years and 10 months after commencing treatment for gastric cancer with simultaneous disseminated peritoneal metastasis. A 45-year-old man was diagnosed as having advanced gastric cancer following the discovery of numerous nodules in the peritoneal cavity at laparotomy. The patient was treated by palliative gastrectomy and continuous hyperthermic peritoneal perfusion (CHPP) immediately after surgery on November 11, 1987. Postoperatively, he underwent radiofrequency (RF) hyperthermia with intraperitoneal cisplatin a total of seven times. He continued on a combination of uracil and tegafur (UFT) administered orally with a protein-bound beta-D-glucan extracted from the mycelia of Cariolus versicolor (PSK). Long-term survival was achieved following the initial palliative gastrectomy despite simultaneous disseminated peritoneal metastasis.

Randomised trial of effects of interferon-alpha on incidence of hepatocellular carcinoma in chronic active hepatitis C with cirrhosis

Patients with chronic active hepatitis C and cirrhosis often develop hepatocellular carcinoma. Interferon (IFN) seems to be effective in some patients but whether it prevents carcinogenesis is unknown. In a prospective randomised controlled trial, we evaluated the effects of IFN-alpha in cirrhotic patients with HCV infection because of their high risk of hepatocellular carcinoma. 90 patients with compensated chronic active hepatitis C with cirrhosis were randomly allocated to receive IFN-alpha (6 MU three times weekly for 12-24 weeks) (45 patients) or symptomatic treatment (45 controls), and were followed up for 2-7 years. In nine controls, alanine aminotransferase (ALT) decreased to less than 80 IU/L but did not stay in the normal range. In 19 patients given IFN-alpha, ALT decreased to less than 80 IU/L (in seven patients, it became and stayed normal; p = 0.011, Wilcoxon rank-sum test). However, the mean change in ALT was not significantly different between the two groups. The mean change in peak alpha-fetoprotein values was smaller in patients given IFN-alpha than in controls (p = 0.021). The mean change in the serum albumin level was higher in the IFN-alpha group (p < 0.001). The histological activity index in the 12 IFN-alpha patients undergoing a second biopsy after therapy was improved (p = 0.031). Hepatitis C viral RNA disappeared in seven (16%) of the 45 IFN-alpha patients (95% CI, 7-29%) and in none of the 45 controls (0-8%; p = 0.018). Hepatocellular carcinoma was detected in two (4%, 1-15%) IFN-alpha patients and 17 (38%, 24-54%) controls (p = 0.002, Wilcoxon signed-rank test). The risk ratio of IFN-alpha treatment versus symptomatic treatment was 0.067 (0.009-0.530; p = 0.010 Cox's proportional hazards). IFN-alpha improved liver function in chronic active hepatitis C with cirrhosis, and its use was associated with a decreased incidence of hepatocellular carcinoma.

Polyamine metabolism in the rat liver after orthotopic liver transplantation

We examined the polyamine metabolism in liver transplanted after cold ischemia and effects of putrescine administration on liver injury, liver regeneration, and survival rate after orthotopic liver transplantation in the rat. Male Wistar rats were used as donors and recipients. Grafts were stored in Euro-Collins solution for 6 h at 4 degrees C. Orthotopic liver transplantation was performed by the three cuff technique. The activities of aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase elevated and peaked 4 h after liver transplantation. Hepatic ornithine decarboxylase and spermidine/spermine N1-acetyltransferase activities were also elevated and peaked 8 h after the operation. In agreement with the increases in ornithine decarboxylase and spermidine/spermine N1-acetyltransferase activities, the putrescine content increased and spermidine content decreased in the transplanted liver. Putrescine administrated intraperitoneally improved the survival rate, decreased serum transaminase level and increased the [3H]thymidine incorporation into the liver DNA. These findings suggest that both biosynthetic and biodegradative pathways are stimulated in liver transplantation, resulting in the increase in the formation of putrescine from ornithine and from spermidine, and that putrescine administration improve the survival rate by protecting the damaged graft after cold ischemia and reperfusion and by stimulating liver regeneration.

Novel colorectal adenocarcinoma-associated 40- and 47-kDa protein antigens recognized by anti-60-kDa heat shock protein antibody

Expression of 40- and 47-kDa proteins recognized by anti-60-kDa heat shock protein antibody was investigated in colorectal adenocarcinoma tissue. In all cases of colorectal adenocarcinoma tissue (n = 9), 40- and 47-kDa proteins were detected by immunoblot analysis. However, expression of these two proteins was extremely low or was not expressed in control tissue. There was no correlation between the quantity of these two bands and histologic type or the location of the tumors. Our results first demonstrate the accumulation of structurally altered 60-kDa heat shock protein-associated antigens in carcinoma tissue and suggest that these two proteins could be a possible candidate for tumor-specific 60-kDa heat shock protein-related protein antigens.

Induction and intracellular localization of a 72-kDa heat shock protein in rat gastric mucosa after water-immersion stress

We investigated the expression and changes in the intracellular localization of a 72-kDa heat shock protein (HSP72) in rat gastric pyloric and fundic mucosa before and after water-immersion stress. Severe mucosal damage was found in the fundic mucosal area of the stomach after this stress. However, no mucosal lesion developed in the pyloric mucosal area. HSP72 in both the soluble and insoluble fractions of the pyloric and the fundic mucosal areas was significantly increased after water-immersion stress, peaking 6h after the initiation of the stress. The increase in HSP72 was more significant in the pyloric mucosal area than in the fundic mucosal area under both normal and stress conditions. The increase of HSP72 in the pyloric mucosal cells occurred prior to the formation of the mucosal lesions, whereas the increase of HSP72 in the fundic mucosal cells was observed after ulcer formation. An immunohistochemical study showed that HSP72 was constitutively expressed in the cytoplasm of the gastric mucosal cells, and that the intranuclear induction of HSP72 was remarkably intense in the pyloric mucosal cells, especially in the proliferative zone, compared with the fundic mucosal cells. Our results may suggest that HSP72 has an important cytoprotective function in gastric mucosal cells and that there is a "biophysical" difference between pyloric and the fundic mucosal cells.

Inhibition of intestinal tumor development in rat multi-organ carcinogenesis and aberrant crypt foci in rat colon carcinogenesis by 22-oxa-calcitriol, a synthetic analogue of 1 alpha, 25-dihydroxyvitamin D3

The modifying effects of 22-oxa-calcitriol (OCT), a synthetic analog of 1 alpha,25-dihydroxyvitamin D3, were assessed in a multi-organ carcinogenesis model using male F344 rats initially treated with five kinds of carcinogens. In experiment 1 the rats were given OCT intraperitoneally at doses of 30 micrograms/kg (25 rats) or 3 micrograms/kg (25 rats), three times a week for 24 weeks after initial carcinogen exposure over 4 weeks and a 2 week non-treatment period. Twenty-two rats received the five carcinogens and were given the vehicle intraperitoneally as a control. A further group of 10 rats was given the 30 micrograms/kg dose of OCT without prior carcinogen application. At the end of the total observation period of 30 weeks the carcinoma incidence in the small intestine of rats given 30 micrograms/kg OCT after carcinogen treatment was 0%. This incidence was significantly smaller when compared with the control group. The incidence of large intestine carcinomas in the 30 micrograms/kg OCT group showed a tendency to decrease. The numbers of small and large intestinal carcinomas per rat were also significantly lower in the group given 30 micrograms/kg OCT than after 3 micrograms/kg OCT or carcinogens alone. Attention was, therefore, focused on colon carcinogenesis and in experiment 2 30 micrograms/kg OCT administered six times a week to rats for 8 weeks after the last injection of N,N'-dimethylhydrazine (DMH) exposure. OCT significantly reduced the formation of DMH-induced aberrant crypt foci, considered to be putative preneoplastic lesions. In experiment 3 30 micrograms/kg OCT was administered six times a week to rats for 4 weeks without prior carcinogen treatment. The proliferating cell nuclear antigen labeling index for the colonic epithelium of rats given 30 micrograms/kg OCT was decreased. Ornithine decarboxylase and spermidine/spermine N1-acetyltransferase activities in colonic epithelium, assayed as indicators of cell proliferation, were not significantly decreased as compared with control group values. Furthermore, vitamin D receptors in colonic epithelium were not significantly increased. Thus the present study indicates that OCT can exert inhibitory effects on tumor development in the small and large intestines, although the mechanism is unclear.

Point mutation of ornithine decarboxylase gene in human hepatocellular carcinoma

Ornithine decarboxylase (ODC) plays an important role in cell growth, and its activity is regulated by many mechanisms. The biochemical characteristics of ODC in malignant cells differ from those of ODC in normal cells. To determine whether novel changes occur in ODC in neoplastic tissue, we compared the nucleotide sequence of ODC cDNA obtained from human hepatoma tissue as determined by reverse transcriptase-PCR with that of ODC cDNA obtained from nontumorous tissue in the same patients. There were three point mutations accompanied by replacements of amino acids in hepatoma tissue with other amino acids or a stop codon. In one poorly differentiated hepatoma, codon 415, CAA was converted to TAA, resulting in replacement of Gln-415 by a stop codon. The mutated ODC protein produced by translation in a reticulocyte-lysate protein synthesizing system was truncated and stabilized in an ATP antizyme-dependent degradation system. These findings suggest that formation of a truncated and stabilized ODC protein due to point mutation is one reason why ODC activity is high in human hepatoma tissue.

[Chronic left ventricular epicardial pacing by the perforated endocardial electrode through the cardiac vein]

We report a rare complication of endocardial pacing electrode implantation. A 64-year-old man, who was implanted transvenous pacemaker system by the other hospital one month ago, visited our outpatient clinic with the complaint of diaphragmatic twitching. Left ventricular pacing was highly suspected because of right bandle branch block pattern by 12 leads ECG. Pericardial effusion was observed by echocardiography, and angiography revealed the pacing electrode coursing through the coronary sinus and perforated the cardiac vein towards the posterior wall of the left ventricle. A new generator and a pacing electrode were implanted on the other side. Pericardial drainage was not performed because hemodynamics was stable. The patient discharged hospital on 18th postoperative day without any complication.

Influence of high glucose on 1,25-dihydroxyvitamin D3-induced effect on human osteoblast-like MG-63 cells

Impaired bone formation due to defective osteoblast function, as reflected in a decreased serum osteocalcin (OC) concentration in the patients with diabetes, has been implicated in the development of diabetic osteopenia. The role of hyperglycemia in this decrease in serum OC concentration was investigated. 1,25-dihydroxyvitamin D3 (1,25[OH]2D3), an active form of vitamin D3, stimulated OC secretion from the human osteosarcoma cell line MG-63 in a dose-dependent manner. Exposure of the cells to high concentrations of glucose for 7 days significantly impaired 1,25(OH)2D3-induced OC secretion as compared with that observed with cells maintained under normal glucose (5.5 mM) or high mannitol conditions. The inhibitory effect of glucose was in a dose-dependent manner up to 55 mM. High glucose (55 mM) also attenuated the 1,25(OH)2D3-induced increase in OC mRNA abundance in MG-63 cells, suggesting that the inhibition of the 1,25(OH)2D3-induced increase in OC secretion by exposure to a high concentration of glucose was, at least in part, mediated at the transcriptional level. High glucose significantly decreased the number of 1,25(OH)2D3 receptors in MG-63 cells, without any change in the dissociation constant for 1,25(OH)2D3; this effect was not mimicked by high mannitol, indicating specificity for glucose. These observations suggest that a high glucose concentration significantly impairs the ability of osteoblastic cells to synthesize OC in response to 1,25(OH)2D3 by reducing 1,25(OH)2D3 receptor number, and that impaired cell function caused by sustained exposure to high glucose contributes to the defect in bone formation observed in the patients with diabetic osteopenia.

Adrenomedullin inhibits the secretion of cytokine-induced neutrophil chemoattractant, a member of the interleukin-8 family, from rat alveolar macrophages

This study was undertaken to determine the effects of adrenomedullin (AM) on the secretion of cytokine-induced neutrophil chemoattractant (CINC), a member of the interleukin-8 family, from lipopolysaccharide-stimulated rat alveolar macrophages in vitro. AM significantly increased cAMP levels in alveolar macrophages in a dose-dependent fashion. On the other hand, AM significantly inhibited CINC secretion from alveolar macrophages in a dose-dependent fashion, and 8-bromo-cyclic adenosine monophosphate (8-Br-cAMP) also significantly inhibited CINC secretion. These findings suggest that AM may play important roles in the regulation of airway inflammation via a cAMP-dependent mechanism.

Long-term depression of naïve synapses in adult hippocampus induced by asynchronous synaptic activity

1. Two independent Schaffer collateral pathways converging to the same pyramidal cell were alternately stimulated by 2-Hz trains (900 pulses) offset by a 150-ms interval in adult rat hippocampal slices. The second input underwent an immediate and persistent long-term depression (LTD). Depression in the first input was smaller than the second input. A narrower interpulse interval (20 ms) failed to induce LTD in either input. 2. Neither the N-methyl-D-aspartate receptor antagonist DL-2-amino-5-phosphonovaleric acid nor the metabotropic glutamate receptor antagonist (+)-alpha-methyl-4-carboxylphenyl-glycine blocked this associative LTD. However, coapplication of these two antagonists blocked LTD. 3. Associative LTD was blocked by prior injection of the Ca2+ chelator bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid into the postsynaptic cell and by bath-applied L-NG-nitroarginine, a nitric oxide synthesis inhibitor. 4. We propose that temporally confined, asynchronous synaptic activity weakens the efficacy of naïve synapses in slices from the adult hippocampus.

Effects of highly hydrogenated soybean oil and cholesterol on plasma, liver cholesterol, and fecal steroids in rats

We investigated the relationship between dietary highly hydrogenated soybean oil (HSO) and cholesterol transport in rats. In the first study, to examine the effects on cholesterol transport of different concentrations of HSO in dietary oil, rats were given one of the three diets containing 0, 25, or 50% HSO in dietary oil with cholesterol (5 g/kg diet) or a diet without HSO and cholesterol for 22 d. Feeding the high concentration of HSO prevented the increase in plasma total cholesterol, hepatic total lipids, and cholesterol and the decrease in high-density lipoprotein-cholesterol, which were caused by dietary cholesterol. Moreover, HSO increased the fecal excretion, fecal lipids, and steroids in a dose-dependent manner. In the second study, to examine the effects on cholesterol transport of redistribution of steric acid in the triacylglycerol species contained in HSO, rats were given one of the six diets containing HSO (distearoylmonoacylglycerol and tristearoylglycerol)-rich, monostearoylglycerol-rich, or palmitic acid-rich oil with/without cholesterol (5 g/kg diet), for 30 d. Whereas the accumulation of cholesterol in the body was reduced, cholesterol excretion was enhanced effectively in rats given the HSO-rich diet compared with rats given the monostearoylglycerol-rich diet. These results suggested that not only the high concentration of stearic acid but also its uneven distribution in HSO-triacylglycerol contributed to the reduction in intestinal cholesterol absorption in rats.

Effects of cyclosporin and ultraviolet radiation on growth and ornithine decarboxylase activity in cultured human epidermal keratinocytes

Both cyclosporin (CyA) and ultraviolet radiation are effective in the treatment of psoriasis, but their precise mechanisms of action are uncertain. We investigated their effects on ornithine decarboxylase (ODC) activity, ODC gene expression, and cellular proliferation stimulated by epidermal growth factor (EGF), in cultured normal human epidermal keratinocytes. CyA (5 micrograms/ml) inhibited ODC activity, ODC mRNA level, and cell growth induced by 50 ng/ml EGF. Ultraviolet B (10 mJ/cm2) irradiation suppressed the induction of ODC, ODC mRNA, and cell proliferation stimulated by EGF, but ultraviolet A (0-15 J/cm2) irradiation inhibited neither EGF-stimulated ODC activity nor cell proliferation. These findings indicate that reduction of ODC activity in CyA- or ultraviolet B-treated human keratinocytes may contribute to the antiproliferative mechanism of these agents. These results also suggest that the regulation of ODC activity by ultraviolet B and A irradiation may be mediated by different signal transduction pathways.

Cancer induction by an organic arsenic compound, dimethylarsinic acid (cacodylic acid), in F344/DuCrj rats after pretreatment with five carcinogens

Arsenic (As) is environmentally ubiquitous and an epidemiologically significant chemical related to certain human cancers. Dimethylarsinic acid (cacodylic acid; DMA) is one of the major methylated metabolites of ingested arsenicals in most mammals. To evaluate the effects of DMA on chemical carcinogenesis, we conducted a multiorgan bioassay in rats given various doses of DMA. One-hundred twenty-four male F344/DuCrj rats were divided randomly into 7 groups (20 rats each for groups 1-5; 12 rats each for groups 6 and 7). To initiate multiple organs and tissues, animals in groups 1-5 were treated sequentially with diethylnitrosamine (100 mg/kg body weight, i.p., single dose at the commencement) and N-methyl-N-nitrosourea (20 mg/kg body weight, i.p., 4 times, on days 5, 8, 11, and 14). Thereafter, rats received 1,2-dimethylhydrazine (40 mg/kg body weight, s.c., 4 times, on days 18, 22, 26, and 30). During the same period, the animals were sequentially administered N-butyl-N-(4-hydroxybutyl)nitrosamine (0.05% in the drinking water, during weeks 1 and 2) and N-bis(2-hydroxypropyl)nitrosamine (0.1% in the drinking water, during weeks 3 and 4; DMBDD treatment). After a 2-week interval, groups 2-5 were given 50, 100, 200, or 400 ppm DMA, respectively, in the drinking water. Groups 6 and 7, which were not given DMBDD treatment, received 100 and 400 ppm DMA during weeks 6-30. All rats were killed at the end of week 30. In the initiated groups (groups 1-5), DMA significantly enhanced the tumor induction in the urinary bladder, kidney, liver, and thyroid gland, with respective incidences in group 5 (400 ppm DMA) being 80, 65, 65, and 45%. Induction of preneoplastic lesions (glutathione S-transferase placental form-positive foci in the liver and atypical tubules in the kidney) was also significantly increased in DMA-treated groups. Ornithine decarboxylase activity in the kidneys of rats treated with 100 ppm DMA was significantly increased compared with control values (P < 0.001). In conclusion, DMA is acting as a promoter of urinary bladder, kidney, liver, and thyroid gland carcinogenesis in rats, and we speculate that this may be related to cancer induction by As in humans.

[Comparison of the long-term results of intra or extracardiac implanted bioprosthetic valves]

The long-term results following intra or extracardiac implanted bioprosthetic valves were compared. Forty-one patients, whose average age at the operation was 43.3 +/- 10.7 (mean +/- SD) year-old, were implanted 33 Hancock and 11 Carpentier-Edwards porcine valves, 35 in mitral, 6 in aortic and 3 in tricuspid position. Twenty-five children, whose average age was 6.0 +/- 3.5 year-old (p < 0.01) at the operation, underwent right ventricular-pulmonary artery conduit repair with 16 Hancock, 7 Carpentier-Edwards porcine valves and 2 Ionescu-Shiley pericardial valves. There were only one late death and one operative death in the patients implanted intracardiac bioprosthetic valves. Seven intracardiac and 12 extracardiac implanted bioprosthetic valves were removed at the reoperation for prosthetic valve dysfunction. The probabilities free from reoperation after 7 and 9 years of follow-up was 91% and 82%, respectively, with intracardiac implanted valves, on the other hand 51% (p < 0.05) and 8.6% (p < 0.05), respectively, with extracardiac implanted valves. Valve dysfunction in extracardiac implantation was mainly related to the stenosis due to fusion of comissure and/or calcification. Regurgitation due to tear and/or perforation was mainly associated with intracardiac implanted bioprosthetic valves.

Long-term potentiation and evidence for novel synaptic association in CA1 stratum oriens of rat hippocampus

In CA1 stratum oriens of hippocampal slices, a robust long-term potentiation (LTP) induced by tetanic stimulation (20 pulses at 100 Hz, 10 trains delivered at 0.1 Hz) was accompanied by a slowly developing potentiation in a second, untetanized pathway. N-methyl-D-aspartate (NMDA) receptor antagonist DL-2-amino-5-phosphonovaleric acid (D-APV, 50 or 100 microM) reduced the homosynaptic LTP by 80% but failed to affect heterosynaptic LTP. The metabotropic receptor antagonist DL-2-amino-3-phosphonopropionic acid DL-AP3, 300 microM) or (+)-alpha-methyl-4-carboxyphenylglycine (MCPG, 500 microM), applied with DL-APV, further reduced homosynaptic LTP and blocked heterosynaptic LTP. The inhibitor of Ca(2+)-induced Ca2+ release dantrolene (20 microM), also applied with DL-APV, blocked both components of LTP. Importantly, when low-frequency test stimulation (0.017 Hz) to the untetanized, heterosynaptic pathway was interrupted for 30 min after homosynaptic tetanization, heterosynaptic LTP did not develop. These results demonstrate homosynaptic and heterosynaptic LTP inductions in stratum oriens of the area CA1 and suggest that the heterosynaptic LTP is induced by NMDA-independent, novel associative processes between tetanized and untetanized pathways.

Studies on carbon material requirements for bacterial proliferation and spore germination under stress conditions: a new mechanism involving transmission of physical signals

The growth of bacteria is often enhanced by addition of carbon materials such as graphite or activated charcoal to the growth medium. In this work, bacterial strains that strictly require such carbon materials under the ordinarily lethal stress caused by high concentrations of salt were isolated. The organisms were gram-positive, spore-forming, sugar-nonfermenting aerobic bacilli and were provisionally designated "Bacillus carbophilus" Kasumi after examination of their phenotypic traits. The growth- and germination-promoting effects of graphite and activated charcoal were demonstrated either quantitatively on agar plates containing fine crystals of the carbon materials mixed with a nonpermissive growth medium or qualitatively on agar plates on nonpermissive growth media half-covered with fine carbon particles. Further experiments demonstrated a novel feature of the phenomenon; i.e., the ability to induce colony formation on the nonpermissive plate was transmissible through the air, as well as through plastic or glass barriers. The mechanism probably involves transmission of physical signals regulating cell growth.

Enhanced inhibitory effects of hyperthermia combined with ascorbic acid on DNA synthesis in Ehrlich ascites tumor cells grown at a low cell density

Effects of hyperthermia and cell densities on inhibitory activity of ascorbic acid on DNA synthesis in Ehrlich ascites tumor cells were studied. When cells at a low density of 5 x 10(3)/ml were treated with 75 microM ascorbic acid for 1 h, DNA synthesis was inhibited after treatment at 37 degrees C and the inhibition was significantly enhanced at 42 degrees C. At a cell density as high as 1 x 10(5)/ml, however, inhibition did not occur at 37 degrees C or 42 degrees C. In contrast, dehydroascorbic acid was inactive even at a low cell density under similar conditions. Inhibitory effects of ascorbic acid on DNA synthesis were also markedly enhanced by treatment at 40 degrees C. DNA synthesis was not inhibited in the absence of the drug. Furthermore, mice transplanted with cells treated with a combination of 75 microM ascorbic acid and hyperthermia at 42 degrees C, considerably prolonged their survival time in comparison with untreated cells. Addition of ascorbic acid to hyperthermia is suggested to be an advantageous treatment for cancer.

Effect of sucrose monostearate, an emulsifier, on polyamine metabolism and phosphatidylinositol turnover in Ehrlich ascites tumor cells

Sucrose esters of fatty acids have antitumor activity. We studied the effect of sucrose monostearate (SS), an emulsifier, on polyamine metabolism and phosphatidylinositol turnover in Ehrlich ascites tumor cells. The activity of ornithine decarboxylase (ODC) was increased in the cells by changing the medium. This increase in the activity was inhibited by adding sucrose stearate, but not sucrose or stearate to the medium. The activity of spermidine/spermine N1-acetyltransferase (SAT), a rate-limiting enzyme of polyamine biodegradation, was enhanced with the addition of SS in a time- and dose-dependent manner. The elevation of SAT activity was completely prevented when cycloheximide was added to the culture simultaneously. In in vitro studies, SS at various concentrations up to 1 mM hardly affected the activities of ODC or SAT. The incorporation of [3H]inositol into both fractions of inositolphospholipid and inositol phosphates was inhibited by SS. These results suggest that the perturbation of polyamine metabolism and phosphatidylinositol turnover is involved in the mechanism of antitumor activity of SS in Ehrlich ascites tumor cells.

Vitamin E acts as a useful chemopreventive agent to reduce spontaneous lung tumorigenesis in mice

The present study was designed to evaluate whether vitamin E could be a useful chemopreventive agent to reduce spontaneous lung tumorigenesis in mice. Starting at 6 weeks of age, groups were divided into three groups, i.e. A/J mice fed a control diet (A/J control), A/J mice fed a vitamin E-supplemented diet (A/J vitamin E) and ddY mice fed a control diet (ddY control). At the 28th experimental week, nuclear NADPH-driven active oxygen generation, thiobarbituric acid reactive substances (TBARS) and DNA single strand breaks (DNA-SSB) in A/J mice fed a control diet were significantly higher than those in the ddY control group. A/J mice fed Vitamin E for 28 weeks could decrease the levels of TBARS and DNA-SSB with a significant difference, as compared with those in A/J control mice. The nuclear alpha-tocopherol levels in A/J controls were significantly lower than those in ddY controls, on the contrary, the vitamin feeding to A/J mice increased nuclear alpha-tocopherol levels more than that in the ddY controls. At the 40th experimental week, lung tumor incidence and tumor multiplicity (percentage of mice with tumors) in A/J controls were reduced and brought close to those in ddY control mice by vitamin E. Then the alpha-tocopherol level in plasma of A/J controls was significantly lower than the level in plasma of ddY controls, and the level in tumor-bearing mice in A/J controls also showed a lower level with significant difference as compared to that in non-tumor-bearing mice of A/J controls. These results suggest that the difference in susceptibility to spontaneous lung tumorigenesis between A/J and ddY mice partly depends on the difference of oxidative stress on the pulmonary nuclei, and vitamin E can act as a useful chemopreventive agent to reduce spontaneous lung tumorigenesis in mice.