Radiation augments a sequential program of differentiation in PKC inhibitor- pretreated mouse epidermal cells

The aim of this study was to determine whether gamma-rays affect differentiation in mouse epidermal cells. After a pre-treatment with the PKC inhibitor staurosporin (STS) or 1-(5-isoquinolinesulfomyl)-2-methylpiperazine (H7), gamma-rays were irradiated with or without an elevation of 0.12 mM Ca2+ and expressions of differentiation markers and each PKC isozyme were examined in normal primary and v-rasHa transformed mouse keratinocytes. Gamma-rays induced the expressions of differentiation markers of keratin 1 and 10 (K1 and 10), filaggrin, loricrin and SPR-1 in normal keratinocytes when the Ca2+ concentration was increased, and these phenomena were augmented in H7 pretreated cells. Similar results were obtained in STS pretreated cells; in this case, gamma-rays enhanced the expressions of the differentiation markers even without an elevated Ca2+ concentration. In v-rasHa transformed cells, gamma-rays induced the expression of differentiation markers not only at 0.05 mM Ca2+, but in 0.12 mM Ca(2+)-shifted cells, and in H7 pretreated cells, these phenomena were augmented. The translocation of PKC alpha to the particulate fraction was seen in H7 pretreated normal keratinocytes. Radiation also induced PKC alpha expression in STS pretreated cells, independent of Ca(2+)-shift, as well as altered expressions of PKC delta and -eta, while expressions of PKC alpha, -delta, -epsilon, and -eta were enhanced in v-rasHa transformed cells. In conclusion, gamma-rays augmented the expressions of both spinous and granular differentiation markers in normal and v-rasHa transformed keratinocytes and this effect was augmented when PKC inhibitors were used, which may be mediated by the cellular redistribution of PKC isozymes.

Interaction of radicicol with members of the heat shock protein 90 family of molecular chaperones

The Hsp90 family of proteins in mammalian cells consists of Hsp90 alpha and beta, Grp94, and Trap-1 (Hsp75). Radicicol, an antifungal antibiotic that inhibits various signal transduction proteins such as v-src, ras, Raf-1, and mos, was found to bind to Hsp90, thus making it the prototype of a second class of Hsp90 inhibitors, distinct from the chemically unrelated benzoquinone ansamycins. We have used two novel methods to immobilize radicicol, allowing for detailed analyses of drug-protein interactions. Using these two approaches, we have studied binding of the drug to N-terminal Hsp90 point mutants expressed by in vitro translation. The results point to important drug contacts with amino acids inside the N-terminal ATP/ADP-binding pocket region and show subtle differences when compared with geldanamycin binding. Radicicol binds more strongly to Hsp90 than to Grp94, the Hsp90 homolog that resides in the endoplasmic reticulum. In contrast to Hsp90, binding of radicicol to Grp94 requires both the N-terminal ATP/ADP-binding domain as well as the adjacent negatively charged region. Radicicol also specifically binds to yeast Hsp90, Escherichia coli HtpG, and a newly described tumor necrosis factor receptor-interacting protein, Trap-1, with greater homology to bacterial HtpG than to Hsp90. Thus, the radicicol-binding site appears to be specific to and is conserved in all members of the Hsp90 family of molecular chaperones from bacteria to mammals, but is not present in other molecular chaperones with nucleotide-binding domains.

CT features of abdominal manifestations of primary antiphospholipid syndrome

PURPOSE

The purpose of this work was to evaluate the CT features of the abdominal manifestations of primary antiphospholipid syndrome (PAPS).

METHOD

Of the 32 patients who were confirmed to have PAPS among 751 patients with elevated antiphospholipid antibodies during a 2 year period, we retrospectively reviewed the 14 patients who underwent abdominal CT. The clinical indications for abdominal CT included abdominal pain, abdominal distension, or lower leg swelling. CT findings were analyzed with regard to the abdominal vascular system and abdominal organ involvement patterns as well as ancillary findings.

RESULTS

Of the 14 patients with PAPS, 10 had involvement of the venous system (72%), 2 of the arterial system (14%), and 2 of both systems (14%). Of the 12 patients who had venous system involvement, 4 had thrombosis in the inferior vena cava (IVC), 2 in both the IVC and the hepatic vein, 1 in the IVC and splenic and portal veins, 1 in the IVC and hepatic and adrenal veins, 1 in the hepatic, portal, and renal veins, and 3 in the portal and superior mesenteric veins. Budd-Chiari syndrome developed in five of the nine patients who had thrombosis of the IVC or hepatic vein. Arterial thrombosis was noted in four patients, hepatic artery in two, aorta in one, renal artery in one, pancreatic arcade in one, and splenic artery in one, with infarct of multiple organs including the liver, jejunum, colon, kidney, and adrenal gland. Seven of the 14 patients (50%) manifested thrombosis or infarct of multiple extra-abdominal organs.

CONCLUSION

PAPS should be included in the differential diagnosis when CT demonstrates infarcts in multiple organs or patients have recurrent episodes of venous or arterial thrombosis.

Inhibition of human malignant glioma growth in vivo by human recombinant plasminogen kringles 1-3

Human malignant gliomas are highly vascularized and aggressive tumors. Angiogenesis inhibitors have been shown to induce regression of a variety of primary and metastatic tumors in vivo. However, their usefulness in treating brain tumors is not well understood. Angiostatin, a multiple kringle (1-4 of 5)-containing fragment of plasminogen, is one of the highly effective natural cryptic angiogenesis inhibitors. In our study, the therapeutic efficacy of non-glycosylated and small molecular size recombinant kringles 1-3 (rPK1-3) was examined in the treatment of brain tumors generated by stereotactic intracerebral implantation of U-87 human glioma cells in nude mice. Mice bearing tumors 7 days post-implant were treated daily with rPK1-3 (100 mg/kg) s.c. for 21 days. Treated animals showed suppressed brain tumor growth by greater than 71.2% along with a 3-fold increase of apoptotic index and suppressed vascularization by 78.9%, without any observable signs of toxicity. Analysis of bFGF and VEGF expression in the tumors of treated animals using immuno-histochemical methods showed near complete absence of growth factors. Our results indicate that the non-glycosylated, small molecular size rPK1-3 is an efficient tumoristatic agent for the treatment of intracranial human glioma xenografts in mice and might provide new strategies for the treatment of brain tumors.

Determination of enzymatic activity and properties of secretory phospholipase A2 by capillary electrophoresis

A capillary electrophoretic (CE) system coupled with a diode array UV detector was used for the assay of secretory phospholipase A2 (sPLA2) activity. This method is based on monitoring both the breakdown of substrates and the formation of products simultaneously using micellar electrokinetic chromatographic techniques. Under our developed separation conditions, we analyzed the substrates and products quantitatively, and investigated enzyme activity as a function of reaction time and presence of enzyme activator or inhibitor. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was also utilized to confirm the phosphatidylcholine, a substrate of sPLA2. In order to test the feasibility of the developed method for measurement of enzymatic activity, we compared it to the conventional radioactive assay method for sPLA2. On the basis of our results, the conventional method can be complemented, or even replaced, by this new CE method which possesses the advantages of short analysis time, use of non-radiolabeled and inexpensive substrates, simple measurement of enzymatic activity, and exact quantitation of substrate and product.

Glibenclamide induces apoptosis through inhibition of cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channels and intracellular Ca(2+) release in HepG2 human hepatoblastoma cells

Glibenclamide, an inhibitor of cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channels, induced apoptosis in a dose- and time-dependent manner in HepG2 human hepatoblastoma cells. Glibenclamide increased intracellular Ca(2+) concentration, which was significantly inhibited by Ca(2+) release blockers dantrolene and TMB-8. BAPTA/AM, an intracellular Ca(2+) chelator, and the Ca(2+) release blockers significantly inhibited glibenclamide-induced apoptosis. Glibanclamide also increased intracellular Cl(-) concentration, which was significantly blocked by CFTR Cl(-) channel activators levamisole and bromotetramisole. These activators also significantly inhibited both intracellular Ca(2+) release and apoptosis induced by glibenclamide. The expression of CFTR protein in the cells was confirmed by Western blot analysis. These results suggest that glibenclamide induced apoptosis through inhibition of CFTR Cl(-) channels and intracellular Ca(2+) release and that this protein may be a good target for treatment of human hepatomas.

Aldose reductase, a key enzyme in the oxidative deamination of norepinephrine in rats

The sympathoneural neurotransmitter norepinephrine (NE) is deaminated to 3,4-dihydroxymandelaldehyde (DHMAL) and subsequently converted to either 3,4-dihydroxymandelic acid (DHMA) or 3,4-dihydroxyphenylglycol (DHPG). In this study, we investigated the relative importance of aldose reductase versus aldehyde reductase in the formation of DHPG from DHMAL. The in vitro incubation of NE with aldose reductase in the presence of monoamine oxidase (MAO) resulted in the formation of DHPG, which was confirmed by mass spectrometry. Although aldehyde reductase also generated DHPG, its activity was much lower than that of aldose reductase. With northern blotting, the expression of both aldose reductase and aldehyde reductase was detected in rat superior cervical ganglia. However, with western blotting, only aldose reductase was immunologically detectable. Treatment of rats with aldose reductase inhibitors for 3 days increased the plasma level of DHMA. There was no correlation between the selectivity of inhibitors and effects on NE metabolite levels. A significant decrease in DHPG, however, was obtained only with an extremely high dose (9 mg/kg/day) of the nonselective inhibitor AL 1576. The present study confirmed that aldose reductase generates DHPG from NE in the presence of MAO. In rat sympathetic neurons, aldose reductase appears to be more important than aldehyde reductase for the formation of DHPG. However, when aldose reductase is inhibited, it appears that aldehyde reductase can compensate for the conversion of DHMAL to DHPG, indicating redundancy in the reduction pathway.

Proton magnetic resonance spectroscopy (1H-MRS) findings for the brain in patients with liver cirrhosis reflect the hepatic functional reserve

OBJECTIVE

Proton magnetic resonance spectroscopy (1H-MRS) has been used to assess the metabolic changes in the brain in patients with liver cirrhosis. Decreased myo-inositol and increased glutamine levels were noted to be the most sensitive spectroscopic markers for cirrhotic patients with hepatic encephalopathy (HE). The purpose of this study was to assess how the abnormalities seen on the 1H-MRS of the brain in patients with liver cirrhosis are related to clinical and laboratory parameters.

METHODS

In a prospective study, localized 1H-MRS was performed in the basal ganglia and parietal white matter regions in liver cirrhosis patients with (n = 48) and without (n = 52) HE and chronic hepatitis (CH) (n = 15), and in normal controls (n = 20).

RESULTS

Among cirrhotic patients, the myo-inositol levels were significantly lower (p < 0.01) and the glutamine levels were higher (p < 0.05) for patients with HE than for those without HE. The myo-inositol and glutamine levels, respectively, were inversely (r = -0.50; p < 0.001) and linearly (r = 0.50; p < 0.001) related to the Child-Pugh score. However, by subgroup analysis of Child-Pugh class C patients, there were no significant differences in the myo-inositol and glutamine levels between cirrhotic patients with (n = 40) and without HE (n = 24). A follow-up study of eight cirrhotic patients with HE showed no significant differences in the myo-inositol and glutamine levels after clinical improvement of HE.

CONCLUSIONS

The abnormalities seen on the 1H-MRS of the brain of patients with liver cirrhosis are not likely to reflect the severity of HE or acute alteration in the level of consciousness. Rather, we believe they represent the chronic metabolic derangement of the brain associated with hepatic functional reserve.

Proliferating cell nuclear antigen and c-erbB-2 oncoprotein expression in adenoid cystic carcinomas of the salivary glands

BACKGROUND

Adenoid cystic carcinoma (ACC) of the salivary gland shows a variable clinical course. It would be helpful to discover reliable biologic markers in the management of patients with ACC.

METHODS

We examined proliferating cell nuclear antigen (PCNA) and c-erbB-2 oncoprotein expression on 30 cases of ACC of the salivary glands. The immunohistochemical results, and size, location, and histologic grade of the tumors were compared with the clinical outcome of the patients.

RESULTS

Mean PCNA positivity of ACCs was 15%, and was higher in solid than in cribriform/tubular areas. High PCNA value was significantly correlated with shorter disease-free and overall survival of the patients with ACC. c-erbB-2 overexpression was observed in only five cases, focally in cribriform/tubular areas. High histologic grade, which was determined by the presence of solid components, showed a trend toward shorter survival. Size and location of ACC were not associated with patient outcome.

CONCLUSIONS

The present study indicates that PCNA score may be one of the most useful prognostic factor of ACC.

Inhibitory effects of constituents of Gastrodia elata Bl. on glutamate-induced apoptosis in IMR-32 human neuroblastoma cells

The inhibitory effects of the constituents of Gastrodia elata Bl. (GE) on glutamate-induced apoptosis in human neuronal cells were investigated using IMR32 human neuroblastoma cells. Glutamate (GLU) induced DNA fragmentation, a hallmark of apoptosis, in a dose-dependent manner. GLU also induced a slow and sustained increase in intracellular Ca2+ concentration. Treatment with EGTA, an extracellular Ca2+ chelator, in a nominal Ca2+-free buffer solution abolished the GLU-induced intracellular Ca2+ increase, indicating that GLU stimulated Ca2+ influx pathway in the IMR32 cells. BAPTA, an intracellular Ca2+ chelator, significantly inhibited the GLU-induced apoptosis assessed by the flow cytometry measuring hypodiploid DNA content indicative of apoptosis, implying that intracellular Ca2+ rise may mediate the apoptotic action of GLU. Vanillin (VAN) and p-hydroxybenzaldehyde (p-HB), known constituents of GE, significantly inhibited both intracellular Ca2+ rise and apoptosis induced by GLU. These results suggest that the apoptosis-inhibitory actions of the constituents of GE may account, at least in part, for the basis of their antiepileptic activities. These results further suggest that intracellular Ca2+ signaling pathway may be a molecular target of the constituents of GE.

Identification of a novel beta-lactamase produced by Xanthomonas campestris, a phytopathogenic bacterium

The Xanthomonas campestris pv. campestris 11 chromosome encodes a periplasmic beta-lactamase of 30 kDa. Gene replacement and complementation confirmed the presence of this enzyme. Its deduced amino acid sequence shows identity and conserved domains between it and Stenotrophomonas maltophilia L2 and other Ambler class A/Bush group 2 beta-lactamases. Southern hybridization detected a single homologous fragment in each of 12 other Xanthomonas strains, indicating that the presence of a beta-lactamase gene is common among xanthomonads.

Cell cycle arrest in endometrial carcinoma cells exposed to gonadotropin-releasing hormone analog

Gonadotropin-releasing hormone (GnRH) has been shown to have an inhibitory effect on the growth of several hormone-dependent human tumors. We have treated a human endometrial cancer cell line which expresses GnRH receptor with GnRH analog, D-Trp6-LHRH, in order to study whether there are differences in cell cycle kinetic response. Flow cytometric analysis revealed that cultured carcinoma cells showed a cell cycle arrest at the G1-S transition after treatment with 10 microM D-Trp6-LHRH for 36 h. Western blot analysis showed that the level of p16 protein was obvious following 24 h of D-Trp6-LHRH treatment. These results suggest that the mechanism by which GnRH inhibits the growth of endometrial carcinoma cells may include effects on cell cycle arrest.

Thalidomide responsiveness in an infant with Behçet's syndrome

BACKGROUND

Behçet's syndrome is a chronic relapsing vasculitis characterized by aphthous stomatitis, genital ulcerations, and uveitis. The disease is a multisystem illness, which may involve the skin, joints, gastrointestinal tract, blood vessels, central nervous system, and other organs.

CASE STUDY

We report a case of an infant with features of Behçet's syndrome who did not respond to conventional immunosuppression with high-dose corticosteroids and cytotoxic agents. Thalidomide, a potent immune response-modifying drug, was used with marked improvement and resolution of symptoms.

CONCLUSION

This finding supports a trial of thalidomide treatment in patients with Behçet's syndrome who are unresponsive to other forms of immunosuppressive therapy or develop undesirable side effects.

Influence of ionizing radiation on induction of apoptotic cell death and cellular redistribution of protein kinase C isozymes in mouse epidermal cells differing in carcinogenesis stages

Although protein kinase C (PKC) plays an important role in cellular response to radiation, little is known about the specific role of each isoform in the radiation induced cellular response. In this study, the induction of apoptosis and subcellular distribution of PKC isoforms after gamma-ray irradiation were examined in three kinds of mouse epidermal cells with different stages of carcinogenesis (normal mouse keratinocytes, PK: v-rasHa transfected mouse keratinocytes, ras-PK; and neoplastic cells from mouse skin papilloma, 308 cells). The induction of apoptosis was different in normal and neoplastic cells; in normal cells after 16 Gy of radiation, apoptosis was 2-10 times higher than that in ras-PK or 308 cells, and was rapidly induced; other cells died more slowly, depending on the stage of carcinogenesis. The responses of each PKC, especially rapid translocation of PKCdelta and no response of PKCepsilon by radiation in normal cells may influence the induction of apoptosis by radiation.

Gender differences in pharmacokinetics and pharmacodynamics of azosemide in rats

Gender differences in pharmacokinetics and pharmacodynamics of azosemide were evaluated after intravenous, 10 mg kg(-1), and oral, 10 mg kg(-1), administration to male and female rats. After intravenous administration to male rats, the percentages of intravenous dose of azosemide recovered from entire gastrointestinal tract at 24 h (13.2 versus 3.93%) was significantly greater than those in female rats. In male rats, the nonrenal clearance of azosemide tended (p<0.066) to be faster and kidney weight tended (p<0.068) to be greater than those in female rats. After oral administration of azosemide to male rats, the 8-h urinary excretion of potassium (0.395 versus 0.766 mmol g(-1) kidney) and 8-h kaluretic efficiency (55.9 versus 284 mmol mg(-1)) decreased significantly compared with female rats.

Prevention of naphthalene-1,2-dihydrodiol-induced lens protein modifications by structurally diverse aldose reductase inhibitors

The effects of aldose reductase inhibitors on lens protein modifications induced by naphthalene-1,2-dihydrodiol were investigated in vitro to confirm the role of aldose reductase on naphthalene cataract formation. HPLC analysis of naphthalene-1, 2-dihydrodiol incubated with aldose reductase and NAD+indicated the formation of a metabolite peak corresponding to 1,2-naphthoquinone. Soluble proteins from rat lenses prepared by gel filtration of crude lens extracts through Sephadex PD-10, incubated with naphthalene-1, 2-dihydrodiol in the presence of NAD+displayed an absorbance ca 450 nm and their spectra were essentially identical to those of 1, 2-naphthoquinone-protein adducts. Similar spectra were also obtained from proteins isolated from the intact rat lens after in vitro incubation in medium containing naphthalene-1,2-dihydrodiol. The spectra obtained from lens proteins incubated with 1, 2-dihydroxynaphthalene were distinct from those of either naphthalene-1,2-dihydrodiol or 1,2-naphthoquinone. Aldose reductase inhibitors possessing either hydantoin or carboxylic acid groups prevented protein modification induced by naphthalene-1, 2-dihydrodiol but not protein modification induced by 1, 2-dihydroxynaphthalene or 1,2-naphthoquinone. Therefore, the metabolite formed from naphthalene-1,2-dihydrodiol by aldose reductase is 1,2-naphthoquinone. Lens proteins modified by naphthalene-1,2-dihydrodiol appear essentially identical to protein adducts formed with 1,2-naphthoquinone and their formation can be prevented by both hydantoin and carboxylic acid containing aldose reductase inhibitors.

A preliminary study of the immunohistochemical detection of a novel tumour marker, 22-1-1 antigen, in gynaecological cancer specimens

A novel tumour associated antigen, 22-1-1, has been recently described in association with a cervical adenocarcinoma cell line. The aims of this paper were to study the tissue distribution of this antigen in sections of gynaecological cancer specimens and to compare it with negative controls. Six cases of cervical cancers, 5 cases of endometrial cancers, 4 cases of ovarian cancers and 5 cases each of normal endometrium and cervix were studied. Immunohistochemical staining using streptoavidin-biotin methodology was used for each tumour specimen. This revealed positive staining for the 22-1-1 antigen in 5 out of 6 cases of cervical cancer, 3 out of 5 cases of endometrial cancers, and all 4 cases of ovarian mucinous cystadenocarcinomas. Importantly, the antigen was expressed in the cytoplasm, cell membrane and glandular lumen of adenocarcinoma cells. The 22-1-1 antigen was not detected in normal uterine tissues except in uterine cervix, in which its expression was observed at low levels. This study shows that the 22-1-1 antigen was expressed in cancer cells derived from the uterus, cervix and the ovary and may be a potential tumour marker in the management of gynaecological cancer patients.

Neuroprotective effects of lamotrigine enhanced by flunarizine in gerbil global ischemia

We examined whether the anti-ischemic effect of lamotrigine (LTG), which inhibits the presynapic sodium channel, could be enhanced by the calcium channel blocker-flunarizine (FNR) in cerebral ischemia. Global ischemia was induced in Mongolian gerbils for 5 min under the monitoring of scalp temperature. LTG and FNR were administered intraperitoneally 1 h before ischemia. After 7 days, animals were killed and viable neurons in CA1 area were counted. LTG treated group showed significant protective effects compared to control group (P < 0.01). These effects were more prominent in group treated with LTG and FNR (P = 0.01). Combination of two drugs did not increase the mortality rate compared to single-treated group. These results show that a synergistic reduction of neuronal death can be achieved by combination of LTG and FNR without serious adverse reaction.

Modified small-bowel follow-through: use of methylcellulose to improve bowel transradiance and prepare barium suspension

PURPOSE

To evaluate the efficacy of barium suspension prepared in methylcellulose (MC) in modified small-bowel follow-through (SBFT).

MATERIALS AND METHODS

The authors evaluated 155 patients who underwent modified SBFT with oral administration of MC after ingesting barium suspension. Of these patients, 52 received 40% suspension in MC, 46 received 40% suspension in water, and 57 received 70% suspension in water. Patients were divided into normal (n = 74) and abnormal (n = 81) groups according to the final results. The image quality, transit time to the cecum, and time to and frequency of flocculation were compared for both groups.

RESULTS

In the normal group, the quality of the images in patients receiving 40% suspension in MC or 70% suspension in water was superior to that of images in patients receiving 40% suspension in water. In the abnormal group, the best image quality was achieved for the patients who received 40% suspension in MC. In the normal group, the difference in transit time between the three preparations was not substantial. In the abnormal group, however, the 40% suspension in MC showed the fastest transit time. Use of the 40% suspension in MC helped lower the frequency of flocculation in the normal group.

CONCLUSION

Use of 40% barium suspension in MC is effective for improving the image quality in modified SBFT.

Percutaneous hot saline injection therapy: effectiveness in large hepatocellular carcinoma

PURPOSE

To report on the efficacy of percutaneous hot saline injection therapy (PSIT) in the treatment of large hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Twenty-nine patients with 31 HCCs underwent PSIT. Physiologic saline was mixed with contrast medium and Lipiodol; this mixture was boiled and injected into the tumor. Mean tumor diameter was 7.0 cm. Initial regression rates were evaluated at 3-month interval with computed tomography (CT) and alpha-fetoprotein level measurement. Cumulative survival rates were calculated with the Kaplan-Meier method. Multivariate analysis using Cox's proportional hazard regression model was performed to determine the significant prognostic factors.

RESULTS

Initial regression rate for all tumors at a 3-month interval was 42% (13 of 31 tumors) and the median survival was 10.0 months (range, 3.0-36.0 months). The significant prognostic factors were encapsulated tumors, tumors less than 10 cm in diameter, tumors with even saline dispersion, tumors with initial regression at 3-month follow-up, and TNM stage II or III rather than IV.

CONCLUSION

PSIT is a feasible alternative treatment for a large HCC when transcatheter arterial chemoembolization is not feasible or has failed.

Different induction of adaptive response to ionizing radiation in normal and neoplastic cells

Since the beneficial effects of low-dose radiation (0.01 Gy) are usually observed in normal cells, we investigated whether the adaptive response was induced by low-dose radiation in neoplastic cells of different origin as well as in normal cells. Cell lines used in this experiment were as follows: mouse lymphocytes (NL); L929 cells established from mouse connective tissue; primary mouse keratinocytes (PK); line 308 from mouse papilloma; X-ray sensitive lymphoma cells, L5178Y-S and EL-4 cells from mouse lymphoma. The adaptive response was determined by cell survival and apoptosis. The involvement of apoptosis in the adaptive response was examined by ELISA and TUNEL assay. Adaptive response was induced by pretreatment with low-dose radiation of 0.01 Gy in normal cells such as NL, L929, and PK, but not in L5178Y-S, EL-4, and line 308 cells. In addition, the reduction of apoptosis by pretreatment with low-dose radiation was observed in NL, L929, and PK, but not in L5178Y-S, EL-4, and line 308 cells. These results suggested that the adaptive response could be induced by pretreatment with low-dose radiation and the phenomena were observed in normal cells, not in neoplastic cells. In addition, pretreatment with low-dose radiation reduced apoptosis, suggesting that an anti-apoptotic pathway may be involved in the adaptive response.

Organophosphate-induced brain injuries: delayed apoptosis mediated by nitric oxide

The features of organophosphate-induced brain injuries were investigated. Rats were poisoned intraperitoneally with 9 mg/kg (1.8 LD(50)) of diisopropylfluorophosphate. Pyridostigmine bromide (0.1 mg/kg) and atropine methylnitrate (20 mg/kg), which are centrally inactive, were pre-treated intramuscularly to reduce the mortality and eliminate peripheral signs. Diisopropylfluorophosphate induced severe limbic seizures, and early necrotic and delayed apoptotic brain injuries. The necrotic brain injury was observed to be maximal as early as 1 h after diisopropylfluorophosphate treatment predominently in hippocampus and piriform/entorhinal cortices, showing a spongiform change (malacia) of neuropils in severe cases. In contrast, typical apoptotic (TUNEL-positive) cells started to appear at 12 h in thalamus, and a mixed type in amygdala. Separately, nitrite/nitrate content in cerebrospinal fluid was found to significantly increase after 2 h, reaching a maximal level at 6 h. Pre-treatment with l-N(G)-nitroarginine, an inhibitor of nitric oxide synthase, reduced nitrite/nitrate content and, noteworthy, attenuated only apoptotic brain injury in all four brain regions without affecting seizure intensity and necrotic injury. Taken together, the delayed apoptotic injury of brain induced by diisopropylfluorophosphate poisoning in rats might be mediated in part through nitric oxide production.

Correlation of changes in natural killer cell activity and glutathione S-transferase placental form positive hepatocytes in diethylnitrosamine-induced rat hepatocarcinogenesis

To evaluate the induction of preneoplastic hepatic foci in relation to natural killer cell (NK) activity, we sequentially analyzed glutathione S-transferase placental form positive (GST-P+) hepatocytes and NK activity during diethylnitrosamine (DEN) and phenobarbital (PB)-induced hepatocarcinogenesis in Sprague-Dawley rats. Previous studies have shown that NK activity can modulate the carcinogenic process induced by chemical carcinogens. Newborn females were initially given a single intraperitoneal injection of 15 mg DEN/kg and three weeks later, they were treated with 500 ppm phenobarbital (PB). From week 3, PB was administered in drinking water for 9 weeks. Interim and terminal sacrifices were performed at weeks 12, 15 and 30. GST-P+ hepatocytes increased with age in DEN-treated rats, especially in the population of more than two GST-P+ hepatocytes. The NK activity of DEN-treated rats did not significantly differ from that of control rats until week 12, but it progressively decreased from week 15 to 30. These results indicate that changes of NK activity inversely correlated with the induction of preneoplastic hepatic foci. This strong correlation of decreased NK activity with enhanced induction of GST-P+ foci suggests that NK activity is important in the early progression of hepatocarcinogenesis in rats.