[Experience of long term survival in a case with surgery for cancer metastasis to brain and mediastinal lymph node from unknown primary site].

We report a rare case of metastatic brain and lymph node carcinoma of unknown primary origin. A 68-year-old man had been followed up after resection of brain metastasis in right parietooccipital region without suspicious primary site. Seventy-eight months after the resection, a mediastinal lymph node (#2R) of 15 mm in diameter was detected by computed tomography (CT) and was surgically removed. The histological diagnosis was poorly differentiated adenocarcinoma resembling lymphoepithelial carcinoma, which was similar to the histology of the previously resected brain tumor. This patient is alive without recurrence and apparent primary site at 24 months after lymph node resection.

The development of a non-contact screening system for rapid medical inspection at a quarantine depot using a laser Doppler blood-flow meter, microwave radar and infrared thermography.

In order to conduct fast screening of passengers with infections such as severe acute respiratory syndrome (SARS) or pandemic influenza at a quarantine depot, we developed a non-contact screening system with self-produced program to conduct a human screening within five seconds, via a linear discriminant function from non-contact derived variables, i.e. palmer pulse derived from a laser Doppler blood-flow meter, respiration rate determined by a 10-GHz microwave radar, and facial temperature measured by thermography. The system evaluation was conducted on seven healthy male subjects (23 +/- 1 years). In order to achieve a pseudo-infection condition, the subjects maintained an ergometer exercise load (100 W, 10 minutes). Before (normal condition) and after (pseudo-infection condition) exercise, a significant linear discriminant function (p < 0.001) was determined to distinguish pseudo-infection condition from normal condition (Mahalanobis D-square = 20.3, classification error rate <5%). The proposed system appears promising for future application in fast screening of infection at a quarantine depot.

Development of a non-contact screening system for rapid medical inspection at a quarantine depot using a laser Doppler blood-flow meter, microwave radar and infrared thermography.

In order to conduct fast screening of passengers with infections such as severe acute respiratory syndrome (SARS) or pandemic influenza at a quarantine depot, we developed a non-contact screening system with a self-produced program to conduct a human screening within five seconds, via a linear discriminant function from non-contact derived variables, i.e. palmer pulse derived from a laser Doppler blood-flow meter, respiration rate determined by a 10-GHz microwave radar, and facial temperature measured by a thermography. The system evaluation was conducted on seven healthy male subjects (23+1 years). In order to achieve a pseudo-infection condition, the subjects maintained an ergo-meter exercise load (100 W, 10 minutes). Before (normal condition) and after (pseudo-infection condition) exercise, a significant linear discriminant function (p50.001) was determined to distinguish the pseudo-infection condition from the normal condition (Mahalanobis D-square 1/4 20.3, classification error rate55%). The proposed system appears promising for future application in fast screening of infection at a quarantine depot.

A novel apparatus for non-contact measurement of heart rate variability: a system to prevent secondary exposure of medical personnel to toxic materials under biochemical hazard conditions, in monitoring sepsis or in predicting multiple organ dysfunction syndrome.

BACKGROUND: The impaired balance of the low-frequency/high-frequency ratio obtained from spectral components of RR intervals can be a diagnostic test for sepsis. In addition, it is known that a reduction of heart rate variability (HRV) is useful in identifying septic patients at risk of the development of multiple organ dysfunction syndrome (MODS). We have reported a non-contact method using a microwave radar to monitor the heart and respiratory rates of a healthy person placed inside an isolator or of experimental animals exposed to toxic materials. APPARATUS DESIGN AND TESTING: With the purpose of preventing secondary exposure of medical personnel to toxic materials under biochemical hazard conditions, we designed a novel apparatus for non-contact measurement of HRV using a 1215 MHz microwave radar, a high-pass filter, and a personal computer. The microwave radar monitors only the small reflected waves from the subject's chest wall, which are modulated by the cardiac and respiratory motion. The high-pass filter enhances the cardiac signal and attenuates the respiratory signal. In a human trial, RR intervals derived from the non-contact apparatus significantly correlated with those derived from ECG (r=0.98, P<0.0001). The non-contact apparatus showed a similar power spectrum of RR intervals to that of ECG. CONCLUSIONS: Our non-contact HRV measurement apparatus appears promising for future pre-hospital monitoring of septic patients or for predicting MODS patients, inside isolators or in the field for mass casualties under biochemical hazard circumstances.

Cerebral endothelial cells are a major source of adrenomedullin.

Adrenomedullin is a peptide hormone with multifunctional biological properties. Its most characteristic effects are the regulation of circulation and the control of fluid and electrolyte homeostasis through peripheral and central nervous system actions. Although adrenomedullin is a vasodilator of cerebral vasculature, and it may be implicated in the pathomechanism of cerebrovascular diseases, the source of adrenomedullin in the cerebral circulation has not been investigated thus far. We measured the secretion of adrenomedullin by radioimmunoassay and detected adrenomedullin mRNA expression by Northern blot analysis in primary cultures of rat cerebral endothelial cells (RCECs), pericytes and astrocytes. We also investigated the expression of specific adrenomedullin receptor components by reverse transcriptase-polymerase chain reaction and intracellular cAMP concentrations in RCECs and pericytes. RCECs had approximately one magnitude higher adrenomedullin production (135 +/- 13 fmol/10(5) cells per 12 h; mean +/- SD, n = 10) compared to that previously reported for other cell types. RCECs secreted adrenomedullin mostly at their luminal cell membrane. Adrenomedullin production was not increased by thrombin, lipopolysaccharide or cytokines, which are known inducers of adrenomedullin release in peripheral endothelial cells, although it was stimulated by astrocyte-derived factors. Pericytes had moderate, while astrocytes had very low basal adrenomedullin secretion. In vivo experiments showed that adrenomedullin plasma concentration in the jugular vein of rats was approximately 50% higher than that in the carotid artery or in the vena cava. Both RCECs and pericytes, which are potential targets of adrenomedullin in cerebral microcirculation, expressed adrenomedullin receptor components, and exhibited a dose-dependent increase in intracellular cAMP concentrations after exogenous adrenomedullin administration. Antisense oligonucleotide treatment significantly reduced adrenomedullin production by RCECs and tended to decrease intraendothelial cAMP concentrations. These findings may suggest an important autocrine and paracrine role for adrenomedullin in the regulation of cerebral circulation and blood-brain barrier functions. Cerebral endothelial cells are a potential source of adrenomedullin in the central nervous system, where adrenomedullin can also be involved in the regulation of neuroendocrine functions.

Adrenomedullin regulates blood-brain barrier functions in vitro.

Adrenomedullin (AM) is an important vasodilator in cerebral circulation, and cerebral endothelial cells are a major source of AM. This in vitro study aimed to determine the AM-induced changes in blood-brain barrier (BBB) functions. AM administration increased, whereas AM antisense oligonucleotide treatment decreased transendothelial electrical resistance. AM incubation decreased BBB permeability for sodium fluorescein (mol. wt 376 Da) but not for Evan's blue albumin (mol. wt 67 kDa), and it also attenuated fluid-phase endocytosis. AM treatment resulted in functional activation of P-glycoprotein efflux pump in vitro. Our results indicate that AM as an autocrine mediator plays an important role in the regulation of BBB properties of the cerebral endothelial cells.

Involvement of the NUP98 gene in a chromosomal translocation t(11;20)(p15;q11.2) in a patient with acute monocytic leukemia (FAB-M5b).

We report here a case of acute monocytic leukemia (M5b subtype according to the French-American-British [FAB] classification) with chromosomal translocation t(11;20)(p15;q11.2). Fluorescence in situ hybridization analysis with a probe for the NUP98 gene, which is located at chromosome band 11p15, showed that the probe hybridized to both derivative chromosomes 11 and 20 as well as to the remaining normal chromosome 11, indicating that the NUP98 gene was split and involved in this translocation. This is the first report of t(11;20)(p15;q11.2) involving the NUP98 gene in overt leukemia.

High prevalence of infection with Entamoeba dispar, but not E. histolytica, in captive macaques.

A total of 268 nonhuman primates (20 species) kept in the Primate Research Institute, Kyoto University, Japan, were surveyed for intestinal amebas. Total positive rates as based on the presence of cysts in the stool following formalin-ether sedimentation were as follows: Entamoeba histolytica/E. dispar, 53%; E. coli, 34%; E. hartmanni, 34%; Iodamoeba buetschlii, 25%; Endolimax nana, 8%; and E. chattoni, 3%. Positive rates were higher in Old World monkeys and lower in New World monkeys. All the 141 E. histolytica/E. dispar-positive animals were Macaca monkeys. The E. histolytica/E. dispar-positive samples were analyzed by polymerase chain reaction (PCR) for identification of E. histolytica and E. dispar. E. dispar DNA was detected in 137 samples, whereas no E. histolytica DNA was seen. Zymodeme analysis and reactivity to monoclonal antibodies of cultured trophozoites also supported the presence of E. dispar and the absence of E. histolytica. When the sera of 93 macaques were examined by an indirect fluorescent antibody test, only 3 animals proved to be positive for E. histolytica, showing the lowest titer. These results demonstrate that infection with E. dispar, but not E. histolytica, is predominant in macaques.

Cadmium-induced mRNA expression of Hsp32 is augmented in metallothionein-I and -II knock-out mice.

Cadmium is toxic and carcinogenic to humans and animals. The testis and lung are the target organs for cadmium carcinogenesis. Heat shock proteins (HSPs) as well as metallothionein (MT) and glutathione (GSH) play an important role in protection against its toxicity. HSP32, also known as heme oxygenase-1, is a 32-kDa protein induced by heme, heavy metals, oxidative stresses, and heat. We investigated expression of the Hsp32 gene of various organs (the liver, lung, heart, stomach, kidney, and testis) in transgenic mice deficient in the MT-I and -II genes (MT-KO) and in control mice (MT-W) after an injection of cadmium chloride (CdCl2). Survival of MT-W mice after a subcutaneously injection of CdCl2 was higher than that of MT-KO mice, while no significant difference was observed in the level of GSH in each organ between MT-W and MT-KO mice. Northern blot analysis showed that the MT-I mRNA was more extensively induced in the liver, kidney, and heart than other organs 6 h after an injection of CdCl2 (30 micromol/kg body wt, sc). There was little increase of the MT-I mRNA in the testis when induced by CdCl2. Expression of the Hsp32 gene in the liver and kidney in response to CdCl2 was more extensively augmented in MT-KO mice than in MT-W mice. In the lung and testis, there was little induction and no augmentation in expression of the Hsp32 gene induced by CdCl2 in both MT-W and MT-KO mice. In the stomach, there was little induction of the Hsp32 mRNA in MT-W mice, but was increased in MT-KO mice. Immunohistochemical staining revealed that the HSP32 protein was strongly expressed in the kidney and liver of MT-W mice 24 h after an injection of CdCl2 (20 micromol/kg body wt, sc), while the expression of HSP32 protein was not increased in the testis. In metabolically active organs such as the liver and kidney, expression of the Hsp32 gene as well as the MT-I gene was extensively induced by cadmium in MT-W mice, and more eminently induced in MT-KO mice. We suggest that organs of low stress response to cadmium such as the testis and lung may be vulnerable target sites for cadmium toxicity and carcinogenesis.

Blunt cell growth potential in carcinogen resistant inbred DRH rats.

A carcinogen-resistant inbred strain DRH/Sea has been developed from the Crj:Donryu strain. The rats had a very low incidence of liver tumors when they were fed diets containing a hepatocarcinogen such as 3'-methyl-4-dimethylamino-azobenzene (3'-Me-DAB). Despite using 3'-Me-DAB during the stage of selection, the DRH/Sea rats developed normally, reproduced and did not have any spontaneous tumor in the lung, liver or uterus at over 1 year of age. Although their growth curves were similar to the Crj:Donryu rats, the progression of polyploidization in the liver was significantly delayed when compared with Crj:Donryu rats. Mitogenic changes that occurred in the liver caused by either 3'-Me-DAB or lead nitrate were less significant in the DRH rats than in Crj:Donryu rats. Furthermore, the growth rate of cultured fibroblasts derived from the DRH rats was slower than that of Crj:Donryu rats. These results, together with our previous results, suggest that slow growth potential is present under certain conditions in DRH rats. These findings may explain partly the meaning of the different susceptibility to hepatocarcinogens.

Transgenic Nicotiana occidentalis Plants Expressing the 50-kDa Protein of Apple chlorotic leaf spot virus Display Increased Susceptibility to Homologous Virus, but Strong Resistance to Grapevine berry inner necrosis virus.

ABSTRACT The 50-kDa protein (P50) encoded by the open reading frame 2 of Apple chlorotic leaf spot virus (ACLSV), a putative movement protein, was expressed in transgenic Nicotiana occidentalis plants. P50 in transgenic plants was mainly detected in a modified form in the cell wall fraction, similar to that in infected leaves. The P50-expressing plants (P50 plants) complemented the systemic spread of the P50-defective mutants of an infectious cDNA clone of ACLSV (pCLSF), indicating that P50 in transgenic plants was functional. Severity of symptoms was greatly enhanced and accumulation of virus in upper leaves was increased in P50 plants inoculated with pCLSF or ACLSV compared with that in nontransgenic control plants (NT plants). Conversely, transgenic plants expressing the coat protein of ACLSV (CP plants) showed a significant delay in symptom development and a reduction of virus accumulation. However, most P50 plants inoculated with Grapevine berry inner necrosis virus (GINV), another species of the genus Trichovirus, neither developed obvious symptoms nor supported virus accumulation in inoculated or upper leaves. In contrast, systemic symptoms developed and virus accumulated equally in NT and CP plants inoculated with GINV. After inoculation with Apple stem grooving virus or Apple stem pitting virus, there was no difference in symptom development and virus accumulation among P50, CP, and NT plants. Our results indicate that transgenic plants expressing a functional P50 were more susceptible to homologous virus and, on the contrary, showed strong resistance to the heterologous virus GINV.

The occurrence of polymorphism of mannose 6-phosphate/insulin-like growth factor 2 receptor gene in laboratory and wild rats.

Carcinogen-resistant inbred DRH rat strain was established from closed colony Donryu rats in the presence of 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB). Despite using 3'-Me-DAB during the stage of selection, the DRH rats developed normally and did not show any spontaneous tumor at over 1 year of age. In the present study, we examined the polymorphism in mannose 6-phosphate/insulin-like growth factor 2 receptor (M6p/Igf2r) gene and found that the DRH rat showed CCC (Proline)-type polymorphism in exon 48 and the Donryu rat had GCC (Alanine) sequence. Since the DRH rat was developed from the Donryu rat, we examined whether this polymorphism in exon 48 of M6p/Igf2r gene was due to mutation that occurred at the stage of selection in the presence of 3'-Me-DAB, using several other laboratory and wild rats. We detected the presence of polymorphism at the same site of the M6p/Igf2r gene among these rats. It is likely that the polymorphism in exon 48 of the M6p/Igf2r gene is present broadly in rats since ancient times and not due to the mutation during the course of selection unless this site is a hot spot for chemical carcinogens.

Assessment of outcome by EC/IC bypass with 123I-iomazenil brain SPECT.

We report two patients with occlusive cerebrovascular disease who were examined by means of benzodiazepine receptor SPECT(BZR-SPECT) with 123I-iomazenil (IMZ) before extracranial-intracranial bypass surgery (EC/IC bypass). Preoperative low perfusion areas detected by cerebral blood flow SPECT (CBF-SPECT) were divided into two parts on BZR-SPECT images. In the low perfusion areas where the BZR were preserved, regional cerebral blood flow (rCBF) increased on postoperative CBF-SPECT, but where the BZR were not preserved, rCBF did not increase on postoperative CBF-SPECT. On visual inspection, the SPECT images of postoperative CBF-SPECT appeared similar to those of preoperative BZR-SPECT. For evaluation of the ischemic brain condition itself, instead of the cerebral metabolism, the distribution and activity of cerebral neurons indicated by BZR-SPECT with IMZ might be utilized.

Attenuation by glutathione of hsp72 gene expression induced by cadmium in cisplatin-resistant human ovarian cancer cells.

Intracellular GSH has some effects on protecting cells against cadmium and is involved in the development of resistance to cisplatin (CDDP). To determine the effects of intracellular GSH on expression of the heat shock genes (hsp) induced by cadmium in CDDP-resistant cancer cells, we used two human ovarian cancer cell lines: CDDP-sensitive A2780 and its CDDP-resistant derivative A2780CP. The concentration of intracellular GSH was significantly higher in A2780CP than in A2780 cells. A2780CP cells were more resistant to CdCl2 exposure than A2780 cells. The treatment of the two cell lines with 50 microM CdCl2 induced hsp72, hsp32 and metallothionein (MT-II) mRNAs, and the induction level of each mRNA did not differ in the two cell lines. However, the treatment with 20 microM CdCl2 induced the hsp72 and hsp32 mRNAs in A2780CP cells less than in A2780 cells, while the MT-II mRNA was induced to similar levels in the two cell lines. The DNA binding activity of the heat shock factor (HSF) in response to 20 microM CdCl2 exposure was also significantly lower in A2780CP cells. The treatment of A2780 cells with N-acetyl-L-cysteine increased the intracellular GSH concentration, and profoundly suppressed hsp72 mRNA induction and HSF activation by CdCl2. These results indicate that the regulation of the hsp72 gene expression induced by CdCl2 was more suppressive in A2780CP than in A2780 cells. Our findings suggest that increased GSH biosynthesis in CDDP-resistant cancer cells may be involved in the attenuation of HSF activation by CdCl2.

Genetic properties for the suppression of development of putative preneoplastic glutathione S-transferase placental form-positive foci in the liver of carcinogen-resistant DRH strain rats.

The post-initiation stage of hepatocarcinogenesis was investigated in carcinogen-resistant inbred DRH rats and the parental strain, carcinogen-sensitive Donryu rats. Male rats at 5 weeks of age from both strains were treated with N-nitrosodiethylamine (200 mg/kg i.p.) followed by feeding with a diet containing 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) from 2 weeks later and were then subjected to partial hepatectomy at 1 week later. At 8 weeks after the start of treatment, the mean area occupied by glutathione S-transferase placental form (GST-P)-positive lesions was about 30% in Donryu rats but less than 4% in DRH rats despite the presence of comparable numbers of foci in the livers of both strains. These observations suggested that clonal expansion of GST-P-positive foci in DRH rat liver was significantly suppressed under these conditions. Furthermore, this genetic property was dominantly inherited in the F1 rats by crosses of DRH and carcinogen-sensitive inbred F344 rats; that is, the induction of GST-P mRNA in the livers of F344 x DRH F1 rats was dominantly suppressed after administration of 3'-Me-DAB for 8 weeks as compared with parental F344 rats under the same conditions. We compared the intrinsic properties related to growth potential of liver cells between adult DRH and Donryu rats. DRH rat liver showed retarded and/or reduced DNA synthesis after partial hepatectomy or a single i.v. injection of lead nitrate and lower activity of telomerase induced by 3'-Me-DAB administration for 1 week, as compared with the Donryu rat liver. The intrinsic properties observed in this study may be related, at least in part, to the low incidence of liver tumors induced by hepatocarcinogens in DRH rats.

Higher induction of heat shock protein 72 by heat stress in cisplatin-resistant than in cisplatin-sensitive cancer cells.

Induction of the heat shock proteins (HSPs) is involved in the increased resistance to cancer therapies such as chemotherapy and hyperthermia. We used two human ovarian cancer cell lines; a cisplatin (CDDP)-sensitive line A2780 and its CDDP-resistant derivative, A2780CP. The concentration of intracellular glutathione (GSH) is higher (2.7-fold increase) in A2780CP cells than in A2780 cells. A mild treatment with a heat stress (42 degrees C for 30 min) induced synthesis of both the heat shock protein 72 (Hsp72) mRNA and the HSP72 protein in A2780CP cells, but not in A2780 cells. In contrast, a severe heat stress (45 degrees C for 30 min) increased synthesis of the HSP72 protein in the two cell lines. The induced level of the HSP72 protein by the severe treatment was higher in A2780CP than in A2780 cells. The gel mobility shift assay showed that DNA binding activities of the heat shock factor (HSF) in the two cell lines were induced similarly and significantly by the mild heat stress. Immunocytochemistry using an anti HSF1 antibody also indicated that mild heat stress activated the HSF1 translocation from the cytosol to the nucleus similarly in the both cell lines. Pretreatment of CDDP-sensitive A2780 cells with N-acetyl-L-cysteine, a precursor of GSH, effectively enhanced induction of the Hsp72 mRNA by the mild heat stress. The present findings demonstrate that induction of the Hsp72 mRNA by the mild heat stress was more extensive in CDDP-resistant A2780CP cells. It is likely that the higher GSH concentration in A2780CP cells plays an important role in promoting Hsp72 gene expression induced by the mild heat stress probably through processes downstream of activation of HSF-DNA binding.

Detection of ALMB-toxin in the larval body of Myrmeleon bore by anti-N-terminus peptide antibodies.

Antibodies were raised against a synthetic antigen carrying the N-terminus peptide of ALMB-toxin, which had been isolated from the antlion, Myrmeleon bore, that exhibited high specificity to the toxin. Analyses with the antibodies showed the toxin to be present mainly at the larval stage and localized in a region from the thorax to abdomen of the larval body.

Studies on the multidrug resistance gene expression in the livers of rats associated with different susceptibility of hepatocarcinogenesis.

Inbred carcinogen-resistant DRH rat strain developed from the closed colony Donryu rats on the basis of selective markers such as poor induction of gamma-glutamyltranspeptidase and marked reduced incidences of liver tumors during 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) administration, which took more than 10 years. Previously, we observed that the Donryu rat liver was quite sensitive to both DNA-damaging and cytotoxic effects of 3'-Me-DAB, while the DRH rat liver showed tolerance to 3'-Me-DAB under the same conditions. In the present study, we examined mRNA levels related to the cytotoxic drug resistance mechanism in the livers of DRH and Donryu rats using RT-PCR. Contrary to our expectation, we observed rather similar levels of mRNAs between the two rat strains under the following conditions: i) mdr1 mRNA induction after 3'-Me-DAB administration. ii) MLP-2 mRNA reduction by 3'-Me-DAB administration, iii) MLP-2 mRNA induction after cholestasis and iv) constitutive levels of cMOAT gene expression. On the other hand, the levels of p53 mRNA and p53 protein in the Donryu rat liver were higher than those in DRH rat liver during 3'-Me-DAB administration, suggesting that the former were more sensitive to 3'-Me-DAB than DRH rat under these conditions. In conclusion, we failed to demonstrate the difference in the cytotoxic drug resistance mechanism between DRH and Donryu rats at least under the conditions examined in this study.

Different responses other than the formation of DNA-adducts between the livers of carcinogen-resistant rats (DRH) and carcinogen-sensitive rats (Donryu) to 3'-methyl-4-dimethylaminoazobenzene administration.

Carcinogen-resistant inbred DRH rats developed from the Donryu strain showed a remarkably low incidence of liver tumors when they were fed diets containing hepatocarcinogens such as 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB). In this work, we examined various characteristics of male DRH and Donryu rats during 3'-Me-DAB administration for 8 weeks. 32P-Postlabeling analysis showed that essentially similar levels of DNA-adducts were generated by the metabolites of 3'-Me-DAB in the livers of these two strains of rats at several time points. However, both GADD45 (growth arrest and DNA damage-inducible) and O6-methylguanine methyltransferase (putatively DNA damage-inducible) mRNA levels were increased significantly in Donryu rat livers, but were increased to a lesser extent in DRH rats. [3H]Thymidine incorporation into hepatic DNA began to increase around 10 to 20 days after the start of 3'-Me-DAB administration in Donryu rats probably due to DNA repair, while no significant change occurred in DRH rats under the same conditions. Furthermore, inductions of heme oxygenase (due to degradation of heme-proteins) and hepatocyte growth factor (HGF; cell death and regeneration of hepatocytes) mRNAs were greater in Donryu rat livers than those of DRH, suggesting that the former were more sensitive to cytotoxic effects of 3'-Me-DAB than the latter. Another remarkable difference observed between these two strains was the significant induction of cytochrome P-450 2E1 mRNA in Donryu rat livers; this may contribute to the generation of reactive oxygen intermediates. Finally, increases of glutathione S-transferase (P-form) and gamma-glutamyltranspeptidase mRNAs as marker enzymes of preneoplastic changes of hepatocytes were clearly seen only in Donryu rat livers at 6 to 8 weeks after the start of 3'-Me-DAB administration. These results indicate that the different susceptibility to hepatocarcinogenesis between these two strains of rats may arise from events other than the DNA adduct formation.

Prompt activation of telomerase by chemical carcinogens in rats detected with a modified TRAP assay.

The maintenance of telomere length is crucial for survival of cells. Telomerase is an RNA-containing reverse transcriptase, which is responsible for elongation of shortened telomeres. Telomerase reactivation has been suggested to be involved in malignant progressions. To study on the involvement of telomerase activation in in vivo carcinogenesis, we first modified the original TRAP assay by changing the primer designs and the labeling method of PCR products to an end-labeling method. Second, we investigated the activation of telomerase in different organs after treatments of rats with various chemical carcinogens. Very early after the beginning of the treatment, telomerase activity in the liver, kidney, and lung was increased. In most cases, telomerase activation occurred in the primary or favorite target organs. The present results suggest that telomerase activation occurs promptly when animals are exposed to chemical carcinogens, which may contribute to in vivo chemical carcinogenesis.