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.

Colonic wall thickening in cirrhotic patients: CT features and its clinical significance

BACKGROUND

To evaluate the computed tomographic (CT) features of colonic wall thickening in cirrhotic patients and to determine their prognostic value.

METHODS

We retrospectively reviewed 28 cirrhotic patients with colonic wall thickening (>/=10 mm) on CT. Twenty-six of the 28 patients had hepatocellular carcinoma. The severity of hepatic dysfunction was determined by using the Child-Pugh classification. We analyzed the patterns of bowel wall thickening and degree of portal hypertension on CT and the survival periods after initial CT detection of colonic wall thickening.

RESULTS

The involved segment of the colon was diffusely thickened with either scalloped or nodular circumferential configuration. In all patients, the thickened colonic wall enhanced poorly. Although the ascending colon was involved in all patients, the transverse (n = 14) or descending (n = 5) colon was also simultaneously involved. Most patients exhibited an advanced stage of portal hypertension on CT. The median survival period of 25 patients who expired was 34 days, and 21 patients (84%) expired within 3 months.

CONCLUSIONS

Colonic wall thickening on CT can be used as one of the indicators of poor prognosis in cirrhotic patients. Advanced liver cirrhosis with significantly severe dysfunction is the likely cause of mortality. Therefore, a less aggressive therapeutic approach is recommended if hepatocellular carcinoma is coexistent in these patients.

Structure of influenza virus panhandle RNA studied by NMR spectroscopy and molecular modeling

The structure of a 34 nucleotide RNA molecule in solution, which contains the conserved panhandle sequences, was determined by NMR spectroscopy and molecular modeling. The partially double-strandedpanhandle structure of the influenza virus RNA serves to regulate initiation and termination of viral transcription as well as polyadenylation. The panhandle RNA consists of internal loop flanked by short helices. The nucleotides at or near the internal loop are crucial for polymerase binding and transcriptional activity. They show more flexible conformational character than the Watson-Crick base-paired region, especially for the backbone torsion angles of alpha, gamma and delta. Although residues A10 and A12 are stacked in the helix, the phosphodiester backbones are distorted. Residues A12, A13 and G25 show dynamic sugar conformations and the backbone conformations of these nucleotides are flexible. This backbone conformation and its associated flexibility may be important for protein-RNA interactions as well as base-specific interactions.

Characterization of atrioventricular nodal reentry with continuous atrioventricular node conduction curve by double atrial extrastimulation

BACKGROUND

Characterization of typical atrioventricular nodal reentrant tachycardia (AVNRT) with continuous AVN conduction (A1A2/A2H2) curves by double atrial extrastimulation (A1A2A3) has never been systematically studied.

METHODS AND RESULTS

This study was composed of 33 patients with typical AVNRT and continuous AVN conduction curves (group 1) and 103 patients with AVNRT and discontinuous AVN conduction curves (group 2). Using A1A2A3 with predefined fast pathway-conducted A2, we examined the effects of slow pathway ablation on the A2A3/A3H3 curves in both groups. In group 1, anterograde AVN effective refractory period (272+/-33 versus 277+/-47 ms, P>0.05) and AVN Wenckebach block cycle length (320+/-45 versus 343+/-59 ms, P>0.05) remained unchanged after ablation. A2H2max was shorter in group 1 than group 2 (237+/-89 versus 395+/-72 ms, P<0.05) at baseline. It shortened in group 2 (395+/-72 versus 221+/-78 ms, P<0.001) but remained unchanged in group 1 (237+/-89 versus 214+/-59 ms, P>0.05) after ablation. A1A2A3 could further disclose discontinuous A2A3/A3H3 curves in 29 patients of group 1. A3H3max shortened in both groups (375+/-81 versus 238+/-82 ms, P<0.001, and 419+/-104 versus 220+/-78 ms, P<0.001, respectively) in a similar fashion. Successful ablation resulted in loss of the left portion of the A2A3/A3H3 curves in the 4 patients of group 1 with continuous A2A3/A3H3 curves.

CONCLUSIONS

Use of A1A2A3 could expose discontinuous A2A3/A3H3 curves in most patients with continuous A1A2/A2H2 curves. Significant shortening of A3H3max after ablation may be indicative of successful elimination of AVNRT.

Early experience with laparoscopic pelvic lymphadenectomy in women with gynecologic malignancy

STUDY OBJECTIVES

To compare the results of laparoscopic pelvic lymphadenectomy with those of open lymphadenectomy; to assess differences in lymph node yield, operating time, and rate of positive nodes based on experience (early and late); and to evaluate the clinical course of laparoscopic lymphadenectomy.

DESIGN

Retrospective case review (Canadian Task Force classification II-2).

SETTING

University-affiliated hospital.

PATIENTS

Sixty-one women with cervical cancer, one with vaginal cancer, and one with endometrial cancer.

INTERVENTIONS

Laparoscopic lymphadenectomy followed by laparotomy or radical vaginal hysterectomy was performed in 19 women between 1994 and 1995, and radical abdominal hysterectomy with pelvic lymphadenectomy was performed in 44 women between 1993 and 1995. MEASUREMENTS AND MAIN RESULTS. Mean lymph node yields at laparoscopic pelvic lymphadenectomy were significantly increased in the group operated during the last 6 months compared with the first 6 months (16.2 +/- 6.8 vs 33.2 +/- 10. 5, p <0.05). After 6 months' experience, lymph node yields were 23.9 +/- 10.3 for laparoscopic lymphadenectomy followed by laparotomy and 23.2 +/- 10.2 for laparoscopic lymphadenectomy followed by radical vaginal hysterectomy (NS). The rate of positive lymph nodes was not significantly different between procedures, 16% and 14%, respectively. Operating time for laparoscopic lymphadenectomy was significantly shorter in the last 6 months (143 +/- 34 vs 78 +/- 18 min, p <0.05). Major complications of the procedure were injury to aberrant obturator and iliac veins in two cases in the early period. Average blood loss was 150 to 350 ml. Two women died due to disease recurrence at minimum of 2.5 years' follow-up; the others were alive without recurrence.

CONCLUSION

Laparoscopic pelvic lymphadenectomy was feasible and safe, and did not compromise short-term survival. A learning curve was associated with the procedure, but after a period of learning, pelvic lymphadenectomy can be performed as effectively by laparoscopy as by laparotomy. (J Am Assoc Gynecol Laparosc 6(1):59-63, 1999)

Neural regulation of phenylethanolamine N-methyltransferase (PNMT) gene expression in bovine chromaffin cells differs from other catecholamine enzyme genes

Expression of the gene encoding the epinephrine-synthesizing enzyme phenylethanolamine N-methyltransferase (PNMT) is regulated by hormonal and neural stimuli. Because the 5'-upstream regions of the PNMT do not contain sequences analogous to those demonstrated to convey neural regulation to the tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) catecholamine-synthesizing enzyme genes, functional and biochemical analyses have been utilized to characterize PNMT promoter responses to cholinergic and depolarizing agents. In primary cultures of bovine adrenal medullary chromaffin cells, reporter gene expression from transiently transfected 3- and 0.9-kb-containing PNMT promoter constructs is stimulated approximately twofold by nicotine and muscarine. Depolarizing concentrations of K+ produce fourfold increases in expression. These responses are not detected with constructs containing the proximal 0.3-kb promoter, indicating that the regions between -273 and -877 bp convey neural responsiveness for the PNMT gene in bovine chromaffin cells. Electrophoretic mobility shift assays (EMSAs) with oligonucleotides encoding these regions of the PNMT promoter revealed distinctions in migration of nuclear protein complexes formed following treatment of chromaffin cells with nicotine, muscarine, or 50 mM K+. Thus, the PNMT promoter between 0.3 and 0.9 kb contains sequences capable of responding to cholinergic and depolarization stimuli. Moreover, these treatments influence the interactions of specific nuclear proteins with this region of the PNMT promoter.

Receptor activator of NF-kappaB recruits multiple TRAF family adaptors and activates c-Jun N-terminal kinase

Receptor activator of NF-kappaB (RANK) is a recently cloned member of the tumor necrosis factor receptor (TNFR) superfamily, and its function has been implicated in osteoclast differentiation and dendritic cell survival. Many of the TNFR family receptors recruit various members of the TNF receptor-associated factor (TRAF) family for transduction of their signals to NF-kappaB and c-Jun N-terminal kinase. In this study, the involvement of TRAF family members and the activation of the JNK pathway in signal transduction by RANK were investigated. TRAF1, 2, 3, 5, and 6 were found to bind RANK in vitro. Association of RANK with each of these TRAF proteins was also detected in vivo. Expression of RANK in cultured cells also induced the activation of JNK, which was blocked by a dominant-negative form of JNK. Furthermore, by employing various C-terminal deletion mutants of RANK, the regions responsible for TRAF interaction and JNK activation were identified. TRAF5 was determined to bind to the C-terminal 11 amino acids and the other TRAF members to a region N-terminal to the TRAF5 binding site. The domain responsible for JNK activation was localized to the same region where TRAF1, 2, 3, and 6 bound, which suggests that these TRAF molecules might mediate the RANK-induced JNK activation.

Inhibition of transforming growth factor-beta 2 expression with phosphorothioate antisense oligonucleotides in U937 cells

Four types of phosphorothioate antisense oligonucleotides for transforming growth factor-beta 2 were synthesized and tested for their antisense activity in U937 cells. The full-length phosphorothioate modified antisense analogues exhibited the highest inhibitory effects on the transforming growth factor-beta 2 expression in U937 cells.

Hyperimmunoglobulin E-recurrent infection syndrome in a patient with juvenile dermatomyositis

A 13-year-old girl presented with multiple skin abscesses. She was diagnosed as having juvenile dermatomyositis (DM) at the age of 7 years. She had suffered from recurrent skin infections, atypical pruritic dermatitis and pneumonia since the age of 8 years. Bacteriologic and fungal cultures for skin abscesses and oral mucosa were positive S. aureus and C. albicans, respectively. Chemotactic defect in peripheral blood neutrophils was observed. The level of serum IgE was markedly elevated, and anti-S.aureus specific IgE was found. A diagnosis of hyperimmunoglobulin E-recurrent infection syndrome (HIE) was made and she was successfully treated with surgical drainage and antibiotics. To our knowledge, this is the first case report of HIE in a patient with juvenile dermatomyositis.

Cloning and expression of a G protein-linked acetylcholine receptor from Caenorhabditis elegans

We have isolated a cDNA clone from the nematode Caenorhabditis elegans that encodes a protein of greatest sequence similarity to muscarinic acetylcholine receptors. This gene codes for a polypeptide of 682 amino acids containing seven putative transmembrane domains. The amino acid identities, excluding a highly variable middle portion of the third intracellular loop, to the human m1-m5 receptors are 28-34%. When this cloned receptor was coexpressed with a G protein-gated inwardly rectifying K+ channel (GIRK1) in Xenopus oocyte, acetylcholine was able to elicit the GIRK current. This acetylcholine-induced current was substantially inhibited by the muscarinic antagonist atropine in a reversible manner. However, another muscarinic agonist oxotremorine and antagonists scopolamine and pirenzepine had little or negligible effects on this receptor. Taken together, these results suggest that the cloned gene encodes a G protein-linked acetylcholine receptor that is most similar to but pharmacologically distinct from muscarinic acetylcholine receptors.

Partial purification of protein farnesyl cysteine carboxyl methyltransferase from bovine brain

C-terminal farnesyl cysteine carboxyl methylation has been known to be the last step in the post-translational modification processes of several important signal transduction proteins in eukaryotes including ras related GTP binding proteins and the gamma-subunit of heterotrimeric G proteins. Protein farnesyl cysteine carboxyl methyltransferase (PFCCMT; EC, 2.1.1.100) catalyzing the reaction is well characterized as being stimulated by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) and suppressed by N-acetyl-S-farnesyl-L-cysteine (AFC). As an initial step to understand the physiological significance of the process, we attempted to purify the enzyme, which was partially purified 130-fold (specific activity, 143 pmol of methyl group transferred/min/mg of protein) with yield of 1.8% after purification by fast protein liquid chromatography (FPLC) on a Superdex 75 column. The enzyme was further purified with non denaturing polyacrylamide gel electrophoresis (ND-PAGE) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of PFCCMT was determined to be about 30 kDa based on Superdex 75 FPLC as well as photoaffinity labelling with S-adenosyl-L-[methyl-3H] methionine ([methyl-3H]SAM). The partially purified enzyme (Superdex 75 eluate) was found to be characteristically affected by GTP gamma S, being activated about 40-fold in 2 mM, in contrast to ATP which did not show any effect on enzyme activity. Meanwhile, the enzyme was found to be markedly inhibited by AFC, reaching 0 activity in 2 mM. These observations strongly suggested that the partially purified enzyme was PFCCMT.

Intracellular Ca2+ mediates lipoxygenase-induced proliferation of U-373 MG human astrocytoma cells

The role of intracellular Ca2+ in the regulation of tumor cell proliferation by products of arachidonic acid (AA) metabolism was investigated using U-373 MG human astrocytoma cells. Treatment with nordihydroguaiaretic acid (NDGA), a lipoxygenase (LOX) inhibitor, or caffeic acid (CA), a specific 5-LOX inhibitor, suppressed proliferation of the tumor cells in a dose-dependent manner. However, indomethacin (Indo), a cyclooxygenase (COX) inhibitor, did not significantly alter proliferation of the tumor cells. At anti-proliferative concentrations, NDGA and CA significantly inhibited intracellular Ca2+ release induced by carbachol, a known intracellular Ca2+ agonist in the tumor cells. Exogenous administration of leukotriene B4 (LTB4), an AA metabolite of LOX pathway, enhanced proliferation of the tumor cells in a concentration-dependent fashion. In addition, LTB4 induced intracellular Ca2+ release. Intracellular Ca2+ inhibitors, such as an intracellular Ca2+ chelator (BAPTA) and intracellular Ca(2+)-release inhibitors (dantrolene and TMB-8), significantly blocked the LTB4-induced enhancement of cell proliferation and intracellular Ca2+ release. These results suggest that LOX activity may be critical for cell proliferation of the human astrocytoma cells and that intracellular Ca2+ may play a major role in the mechanism of action of LOX.

Induction of quinone reductase by a methanol extract of Scutellaria baicalensis and its flavonoids in murine Hepa 1c1c7 cells

The effect of extracts of scutellariae radix (Scutellaria baicalensis Georgi) and its flavonoids, baicalin, baicalein and wogonin, on induction of quinone reductase (QR) in the Hepa 1c1c7 murine hepatoma cell line was examined. A significant and dose-dependent induction of QR activity was observed in the methanol extract of scutellariae radix and baicalin. HPCL analysis showed that baicalin was contained as a main component in the methanol extract of scutellariae radix, indicating that baicalin may be the major active principle of QR induction mediated by scutellariae radix extract. To elucidate the mechanism of baicalin-mediated induction of QR enzyme activity, the effect on QR mRNA levels in Hepa 1c1c7 cell cultures was investigated. Using reverse transcriptase-polymerase chain reaction techniques, time- and dose-dependent induction of QR mRNA levels by baicalin were demonstrated in Hepa 1c1c7 cells. On the basis of these results, the scutellariae radix extract or baicalin can be regarded as a readily available, promising, novel cancer chemopreventive agent.

The Gln-Arg 191 polymorphism of the human paraoxonase gene is not associated with the risk of coronary artery disease among Chinese in Taiwan

Paraoxonase (PON1) is a high density lipoprotein-associated enzyme capable of hydrolyzing lipid peroxides, and thus, might protect lipoproteins from oxidation. A common polymorphism due to an amino acid substitution (Gln-Arg) at codon 191 is considered to be a major determinant of variation in serum PON1 activity. Recent studies have suggested that the PON1-191 polymorphism is an independent risk factor for coronary atherosclerosis in patients with or without diabetes mellitus. The association of PON1-191 polymorphism genotypes and coronary artery disease (CAD) among Chinese subjects in Taiwan was examined. The genotype of 218 angiographically documented CAD patients and the same number of age- and sex-matched control subjects was determined. Genotypes AA, AB and BB were present in 25 (11%), 102 (47%) and 91 (42%) of control subjects, respectively, and in 30 (14%), 96 (44%) and 92 (42%) of CAD patients, respectively (chi2 = 0.57, P = 0.75 between groups). The frequency of the A allele was 0.36 for the control group and 0.35 for CAD patients (P = 0.94). No significant differences in the PON1-191 genotype frequencies could be found between groups when multivariate logistic regression analysis was performed, or different subgroups of age, sex or risk factors were analyzed. Among control subjects, there was also no significant difference between genotypes of the PON1-191 polymorphism and various clinical and lipid variables. In conclusion, our data suggest that there is no association between the Gln-Arg 191 polymorphism of the human PON1 gene and CAD among Chinese subjects in Taiwan.

Mutation of the uracil DNA glycosylase gene detected in glioblastoma

Despite extensive characterization of genetic changes in gliomas, the underlying etiology of these tumors remains largely unknown. Spontaneous DNA damage due to hydrolysis, methylation, and oxidation is a frequent event in the brain. Failure of DNA repair following this damage may contribute to tumorigenesis of gliomas. Uracil DNA glycosylase (UDG), an enzyme which excises uracil from DNA, is an important component of the base excision repair pathway. The sequence of a human homologue of uracil DNA glycosylase gene (UNG) has been recently identified. We performed PCR-based SSCP mutational analysis of UNG in 11 sporadic gliomas (six glioblastomas, two anaplastic astrocytomas, and three oligodendrogliomas) and eight glioblastoma cell lines. One out of six sporadic glioblastomas had a point mutation in exon 3, which resulted in a missense mutation in codon 143. None of the eight glioblastoma cell lines or the five non-glioblastoma sporadic gliomas showed a mutation. Genetic alterations of UNG may play a role in the development of a subset of primary glioblastomas.

Differentiation of cultured human epidermal keratinocytes at high cell densities is mediated by endogenous activation of the protein kinase C signaling pathway

Normal human epidermal keratinocytes (NHEK) grown in serum-free medium on a plastic substrate spontaneously differentiate at high cell densities in vitro. Because protein kinase C (PKC) regulates murine keratinocyte differentiation triggered by a variety of stimuli, we examined the role of this signaling pathway in density-dependent activation of NHEK differentiation. Relative to subconfluent cultures, confluent NHEK expressed markedly higher levels of multiple differentiation markers assayed by immunoblotting, including keratin 1, loricrin, filaggrin, involucrin, TGK, and SPR-1. Expression of several of these markers continued to increase for several days after cells reached confluency. The total level of several PKC isoforms was not substantially altered in NHEK harvested at different cell densities, based on immunoblotting; however, subcellular fractionation revealed that PKCalpha underwent a redistribution to the particulate fraction in confluent and postconfluent NHEK cultures, suggesting that this isozyme was activated under these conditions and may be involved in triggering the terminal differentiation program. Supporting this concept, inhibition of PKC function using bryostatin 1 or GF 109203X blocked the induction of keratinocyte differentiation markers at high cell densities. These data suggest that endogenous activation of PKC is responsible for cell density-mediated stimulation of NHEK differentiation, establishing a critical role for this pathway in regulating human as well as murine keratinocyte differentiation.

Enzyme-linked immunosorbent assay for serum procollagen type III peptide in rats with hepatic fibrosis

The process of hepatic fibrosis, and the changes in contents of hepatic hyproxyproline (HYP) and serum procollagen type III peptide (PIIINP) were examined in two rat models for hepatic fibrosis, i.e. bile duct ligation/scission (BDL/s)- and dimethylnitrosamine (DMN)-induced models. In addition, an expression of type III collagen mRNA in the liver of BDL/s model was also examined. In BDL/s model, hepatic fibrosis started at 2 weeks after operation (WAO) and cirrhosis with prominent bile duct hyperplasia was detected at and after 5 WAO. Serum PIIINP content measured using a modified double armed inhibition enzyme-linked immunosorbent assay (ELISA) method proposed by us started to increase at 1 WAO and continued to increase thereafter. Hepatic HYP content measured colorimetrically started to increase at 3 WAO and it continued to increase until 7 WAO. An expression of type III collagen mRNA in the liver was enhanced at and after 2 WAO, especially at 4 and 5 WAO. In DMN model, marked hepatic fibrosis was detected at 1 week after the last DMN administration (WAA), and the degree of fibrosis was apparently reduced at 4 WAA. Serum PIIINP content prominently increased at 1 WAA and decreased at and after 3 WAA. Hepatic HYP content showed a marked increase at 1 WAA and decreased thereafter. The present results indicated that the sequences of hepatic fibrosis, hepatic HYP content and serum PIIINP content were well correlated with each other in both BDL/s and DMN models. In conclusion, ELISA system for the detection of serum PIINP content is considered to be reliable method for assessment of cirrhotic liver, and the present two rat models for liver fibrosis/cirrhosis seems to be a good tool for researching antifibrotic agents.

Ultrastructural and biochemical characterization of catecholamine release mechanisms in cultured human pheochromocytoma cells

OBJECTIVE

To characterize ultrastructurally and biochemically catecholamine release mechanisms of cultured human pheochromocytoma cells in the basal and stimulated states.

METHODS

The cultured pheochromocytoma cells were prepared from human adrenal pheochromocytoma tumors. Biochemical determinations of catecholamine secretion from the cultured cells were carried out in the basal and stimulated states. Transmission electron microscopy was used to observe the modes of catecholamine release from the cells without and with stimulation by depolarization of the cells with the administration of 50 mmol/L KCl.

RESULTS

Biochemical determinations consistently showed spontaneous secretion of catecholamines from the cultured cells in the basal state without stimulation. Catecholamine release in a calcium-dependent manner could be enhanced in the cells in response to high extracellular potassium concentration. A series of electron microscopic observations of the cultured cells consistently disclosed the classical exocytotic profiles on the cell surface in the basal state. In addition to abundant increase in the number of classical single exocytosis, compound exocytosis was frequently observed in the stimulated cells. Furthermore, other modes of catecholamine release mechanism involving the formation of pseudopodial and/or tubule-like structures, which were different from classical exocytosis, were often present in the intensely stimulation cells.

CONCLUSIONS

Based on the biochemical and electron microscopic findings, we concluded: (1) classical single exocytosis is considered to be a primary mechanism responsible for spontaneous secretion of catecholamines from the cells in the basal state; (2) compound exocytosis is an essential mechanism for extruding large amounts of catecholamines in the stimulated cells; and (3) other modes of catecholamine release mechanism may operate in the cells in response to intense stimulation. These morphological data may be helpful in explanation of biochemical variability and extreme diversity of clinical manifestations in patients with pheochromocytoma tumor.

Changes in natural killer cell activity and prostaglandin E2 levels during the progression of diethylnitrosamine-induced hepatocarcinogenesis in Fischer 344 rats

The sequential changes of natural killer cell (NK) activity and prostaglandin E2 (PGE2) during hepatocarcinogenesis induced by diethylnitrosamine (DEN) in male Fischer 344 rats were investigated. DEN at a concentration of 40 ppm was administered in drinking water for 10 weeks. At weeks 5, 10, 20 and 30, rats were autopsied and the development of glutathione S-transferase placental form positive foci (GST-P+ foci) at weeks 5 and 10 and hepatocellular tumors at weeks 20 and 30 were examined. The labeling index of bromodeoxyuridine (BrdU) an indicator of DNA synthesis, was also sequentially checked. GST-P+ foci were found to increase with age. Hepatocellular nodules increased until week 20, but by week 30 when the incidence of hepatocellular carcinoma was 100%, the incidence of nodules had decreased. BrdU positive cells also increased with age, and by week 30 when the incidence of hepatocellular carcinoma was 100%, the number of BrdU-positive cells had decreased. NK cell activity increased until week 10, but at week 20, was less than in the untreated control group. The level of PGE2 increased until week 5, but at week 10, levels were not significantly different from those seen in the untreated control group. On the basis of these results, we concluded that NK activity is closely related to the progression of hepatocarcinogenesis, but PGE2 levels show no significant change.

Autofluorescence in normal and malignant human oral tissues and in DMBA-induced hamster buccal pouch carcinogenesis

Light-induced fluorescence spectroscopy was conducted on human oral malignant and normal tissues. Under 330-nm excitation wavelength, significant differences in fluorescence intensity were observed around 380- and 460-nm emission. Furthermore, 7,12-dimethylbenz[a]anthracene (DMBA)-induced carcinogenesis in hamster buccal pouch was investigated to elucidate whether similar alterations of fluorescence spectroscopy occurred during the development of squamous cell carcinoma. Similar to the spectral profiles of human oral malignant and normal tissues, the most intense fluorescence peaks in the pouches occurred at 380 nm and 460 nm emission under 330 nm excitation wavelength. At 380 nm emission, the fluorescence intensity of normal pouch mucosa was stronger than those of DMBA-treated abnormal tissues at different stages of carcinogenesis. However, at 460 nm emission, the fluorescence intensity of DMBA-treated tissues was not only stronger than that of normal pouch mucosa but also shifted to 470 nm. These results suggest that under 330 nm excitation wavelength fluorescence spectroscopy may be useful for the detection of oral malignant lesions.

Minimum effective dose of casein phosphopeptides (CPP) for enhancement of calcium absorption in growing rats

We examined the effect of ingested casein phosphopeptides (CPP) on intestinal calcium (Ca) absorption and determined the minimum effective dose for enhancement of Ca absorption under conditions of marginal dietary Ca levels. Male Sprague-Dawley rats, divided upon weaning into five groups, were fed a control diet (isolated soyprotein, ISP; 20%) or a CPP diet (ISP + CPP; 20%, CPP/Ca: 0.1, 0.2, 0.35 and 1.0) for 4 weeks. All diets contained the same amounts of Ca (0.35%) and phosphorus (0.70%). The apparent Ca absorption, the retention of Ca, and the luminal soluble Ca content in the small intestine as determined at 4 weeks in the rats fed CPP diet with a weight ratio of CPP/Ca of more than 0.2 were significantly (p < 0.05) higher than those in the rats fed control diet. The wet weight, length and Ca content of the femur were not significantly different among the groups. These results indicate that the minimum effective dose of CPP for enhancement of Ca absorption is 0.7 g/kg or a weight ratio of CPP/Ca of 0.2 in the ISP diet and that CPP supplementation has the effect of significantly increasing Ca absorption at least under conditions of marginal dietary Ca levels.

Maternal or paternal exposure to radiation increases susceptibility to the induction of glutathione S-transferase-positive hepatic foci in offspring rats

Experiments were conducted to determine whether gamma-ray-induced genetic damage in parental rats can lead to the development of cancer in their offspring rats using glutathione S-transferase-positive (GST-P+) hepatic foci with or without the addition of diethylnitrosamine (DEN), a carcinogen. A single 1 Gy whole-body exposure of gamma-rays was given to pregnant rats at day 14 and during postnatal week 3, DEN was intraperitoneally injected twice in 1 week. Female pups from irradiated maternal and paternal rats were also used. Twelve weeks after birth, the rats were sacrificed. GST-P+ foci in animals subjected only to radiation were not different to those of normal control pups, but the incidence of GST-P+ foci was 2.4 times higher in pups treated with DEN alone at 3 weeks after birth than in those irradiated after the onset of pregnancy. In DEN-combined groups, irradiation of post-pregnant or maternal and paternal rats with gamma-rays before mating significantly increased both the incidence and area of GST-P+ foci when compared to those of rats treated with DEN alone. The proliferating cell nuclear antigen (PCNA) labeling index was significantly higher in the offspring of rats subjected to radiation alone or radiation combined with DEN than in normal control pups. Using a rat-liver model, the results of this study indicate that although the dose did not induce phenotypic malformation, exposure to radiation during the embryonic or pre-embryonic stage increases susceptibility to carcinogens.

Immunological properties of recombinant hepatitis B surface antigen expressed in mammalian cell (C127)

We examined the immunological properties of the recombinant hepatitis B surface antigen (r-HBsAg) which was expressed in mammalian cell (C127). The cross-immunity of r-HBsAg and plasma-derived hepatitis B surface antigen (p-HBsAg) were tested using Western blotting and ELISA with guinea pig polyclonal antibody and naturally infected human-derived antibody and the both antigens show the same results in their response pattern and intensity, which indicate they have a good cross-immunity. From the measurement of ED50 after formalin- or heat-inactivation, both r-HBsAg and p-HBsAg showed ED50 of 0.2-0.3 in formalin-inactivation, while r-HBsAg was 0.05-0.09 and p-HBsAg was 0.03-0.07 in heat-inactivation, which means heat-inactivation method is 3-4 times superior in immunogenicity. In the immunopersistency test performed in guinea pig for the period of 3 months with two different adjuvants, antibody titer was 34.2 with muramyl dipeptide adjuvant, which was 1.8 times greater than the antibody titer of 18.9 with AlPO4 adjuvant. The mutagenicity of r-HBsAg, examined by Ames test and micronucleus test, were all negative. In conclusion, r-HBsAg has the same cross-immunity with p-HBsAg, and heat-inactivation method and muramyl dipeptide adjuvant allow development of r-HBsAg vaccine with excellent immunogenicity.