Toxicity and health-related quality of life during and after high dose rate brachytherapy followed by external beam radiotherapy for prostate cancer

BACKGROUND

The optimal protocol for combining high dose rate brachytherapy and external beam irradiation as treatment for localized prostate cancer is unknown. Toxicity rates and clinical and biochemical outcomes should be evaluated to validate the current treatment protocol.

METHODS

Fifty-eight patients were treated for prostate cancer with high dose rate brachytherapy followed by 30 Gy of external beam radiation therapy. Toxicity during treatment and for 12-18 months thereafter, and treatment-related morbidity, were evaluated. Physician-assessed treatment-related toxicity was graded at the time of occurrence using the Radiation Therapy Oncology Group morbidity criteria. Four separate self-administered questionnaires were used to collect longitudinally demographic data and general and prostate disease-related measures of quality of life.

RESULTS

Various degrees of rectal bleeding due to radiation proctitis were experienced by 13 patients (22%) at a median time of 11 months. Two of these patients needed hospitalization to undergo laser coagulation of the rectal mucosa. Study patients had statistically significant decreases in five SF-36 domains during the first month of treatment. All measures recovered by 12 months. Sexual function was not affected by irradiation. Lower urinary tract symptoms assessed by IPSS/QOL scores worsened significantly during the first month of treatment but later recovered to baseline levels. Physician-assessed RTOG scores failed to detect these changes.

CONCLUSIONS

Morbidity associated with combined radiation therapy was greatest during the first month of treatment and affected quality of life significantly. Most measures recovered to baseline levels by 12 months following radiation therapy. Although the current protocol appears acceptable, measures should be taken to decrease treatment-related morbidity further.

Effects of CCK2 receptor blockade on growth parameters in gastrointestinal tract and pancreas in rats

Gastrin has a growth-promoting effect on the oxyntic mucosa of the stomach but has been claimed also to affect other parts of the gastrointestinal tract and pancreas. This report describes the effects of the cholecystokinin, (CCK2) receptor antagonists YM022 and YF476 on various growth parameters in the gastrointestinal tract and pancreas of the rat. YM022 and YF476 were given subcutaneously in doses known to produce maximum and sustained CCK2 receptor blockade. The body weight was not affected. However, the oxyntic mucosal weight, thickness and protein and DNA contents were reduced by 15-20% already within 1-2 days and by about 30% after 4-8 weeks of CCK2 receptor blockade. Hence, the response of the oxyntic mucosa to CCK2 receptor blockade was in the form of hypotrophy (reduced protein content) and hypoplasia (reduced DNA content). There were no obvious effects of CCK2 receptor blockade on the intestine or pancreas (nor on liver, kidney or thyroid). The proton pump inhibitor omeprazole was used to induce hypergastrinaemia and was given with or without YM022. Omeprazole treatment for 4 weeks increased the oxyntic mucosal weight and thickness by 15-20%. YM022 prevented these effects. We conclude that while elevated circulating gastrin levels, acting on CCK2 receptors, exert a growth-promoting effect on the oxyntic mucosa (but not elsewhere), normal serum gastrin levels exert a mucosa-preserving effect.

Comparison of the kinetic disposition of and serum gastrin change by lansoprazole versus rabeprazole during an 8-day dosing scheme in relation to CYP2C19 polymorphism

BACKGROUND

Little is known about differences in the disposition kinetics and pharmacological effects on gastrin levels between lansoprazole and rabeprazole given in a repeated dosing scheme with respect to the polymorphic CYP2C19.

AIM

To provide preliminary information that should be considered when prescribing proton-pump inhibitors (PPIs) for the treatment of acid-related diseases with reference to the CYP2C/9 genotypic status.

METHODS

Helicobacter pylori-negative healthy volunteers were divided into the following three groups (n = 5 each) on the basis of genotyping for CYP2C19: homozygous (hmEMs) and heterozygous extensive metabolizers (htEMs), and poor metabolizers (PMs). All received once-daily 30-mg doses of lansoprazole or 10-mg doses of rabeprazole during an 8-day course in a crossover manner.

RESULTS

The relative values for the area under the serum concentration-time curve (AUC) of lansoprazole and rabeprazole in the hmEMs, htEMs, and PMs after the final doses were 1:1.7:3.9 and 1:1.7:3.8, respectively. The relative AUCs of gastrin in the hmEMs, htEMs, and PMs were 1.6:2.6:3.1 for lansoprazole and 1.6:2.6:2.9 for rabeprazole, respectively.

CONCLUSION

The disposition kinetic behavior of the two PPIs is co-segregated with CYP2C19. The magnitude of CYP2C19-dependent drug availability in the systemic circulation and resulting gastrin response appears to be fairly similar between the two drugs within the same CYP2C19 genotypic groups after a multiple-dosing regimen.

Extended transsphenoidal approach with submucosal posterior ethmoidectomy for parasellar tumors. Technical note

The authors have developed an extended transsphenoidal approach with submucosal posterior ethmoidectomy for resection of tumors located in the cavernous sinus or the suprasellar region that are difficult to remove via the conventional transsphenoidal approach. Surgery was performed using this approach in 14 patients with large pituitary adenomas, three patients with craniopharyngiomas, and one patient with a meningioma of the tuberculum sellae. The submucosal dissection of the nasal septum used in the conventional transsphenoidal approach was extended to the superior lateral wall of the nasal cavity to expose the bony surface of the superior turbinate lying under the nasal mucosa. Submucosal posterior ethmoidectomy widened the area visualized through the conventional transsphenoidal approach both superiorly and laterally. This provided a safer and less invasive access to lesions in the cavernous sinus or the suprasellar region through the sphenoid sinus. Using this approach the authors encountered no postoperative complications, such as olfactory disturbance, cranial nerve palsy, or arterial injury. In this article the authors present the surgical methods used in this approach.

Five quantitative trait loci affecting 4-nitroquinoline 1-oxide-induced tongue cancer in the rat

In our previous study, Dark-Agouti (DA) rats were found to be highly susceptible to 4-nitroquinoline 1-oxide (4NQO)-induced tongue carcinoma (TC), whereas Wistar / Furth (WF) rats were barely susceptible. Interval mapping analysis of reciprocal backcross rats showed two quantitative trait loci (QTL) on rat chromosomes (RNO) 1 and 19. In the present study, a composite interval mapping analysis was applied to 4NQO-induced TC in 130 (DA x WF) F2 rats, demonstrating five independent QTL, Tongue squamous cell carcinoma 1 - 5 (Tscc1 - 5), responsible for phenotypic differences in the size and number of TCs in the two strains. Two of these QTL were mapped on RNO1, and the others were mapped on RNO4, 14, and 19. The DA allele at these loci consistently yielded semidominant susceptibility to TC. Out of the five loci detected in this F2 generation, Tscc1 and 2 were identical to Stc1 and Rtc1 described in our previous study, but the other three were novel. We propose a new nomenclature consistent with their function. Genome-wide screening of the F2 progeny also suggested the presence of three additional QTL on RNO5, 6, and 10. The possible roles of these loci in tongue carcinogenesis are discussed.

Biological and genetic characterization of a human immunodeficiency virus strain resistant to CXCR4 antagonist T134

The chemokine receptors CXCR4 and CCR5 are considered to be potential targets for the inhibition of HIV-1 replication. We have reported that T134 and T140 inhibited X4 HIV-1 infection specifically because they acted as CXCR4 antagonists. In the present study, we have generated a T134-resistant virus (trHIV-1(NL4-3)) in a cell culture with gradually increasing concentrations of the compound. The EC(50) of T134 against trHIV-1(NL4-3) recovered after 145 passages was 15 times greater than that against wild-type HIV-1(NL4-3). This adapted virus was resistant to other CXCR4 antagonists, T140, AMD3100, and ALX40-4C, and SDF-1; from 10 to 145 times greater than that against wild-type HIV-1(NL4-3). On the other hand, T134, T140, and ALX40-4C were still active against AMD3100-resistant viruses (arHIV-1(018A)). The trHIV-1(NL4-3) contained the following mutations in the V3 loop of gp120: N269K, Q278T, R279K, A284V, F285L, V286Y, I288T, K290E, N293D, M294I, and Q296K; an insertion of T at 290; and Delta274-275 (SI). In addition, many other mutations were recognized in the V1, V2, and V4 domains. Thus, resistance to T134 may be the consequence of amino acid substitutions in the envelope glycoprotein of X4 HIV-1. The trHIV-1(NL4-3) could not utilize CCR5 as an HIV infection coreceptor, although many amino acid substitutions were recognized. The trHIV-1(NL4-3) acquired resistance to vMIP II, which could inhibit both X4 and R5 HIV-1 infection. However, neither the ligands of CCR5, RANTES, and MIP-1alpha, nor a CCR5 low molecular antagonist, TAK-779, were able to influence the infection of trHIV-1(NL4-3). Those results indicated that alternation of coreceptor usage of trHIV-1(NL4-3) was not induced.

Loss of heterozygosity of the mannose 6-phosphate/insulin-like growth factor II receptor and p53 genes in human hepatocellular carcinoma

Information about M6P/IGF2R and p53 genes in hepatocarcinogenesis is limited and controversial. We tested the loss of heterozygosity (LOH) of M6P/IGF2R and p53 genes in cirrhotic and neoplastic foci in surgically resected livers of 30 patients with hepatocellular carcinoma (HCC). The DNAs extracted from microdissected specimens were used for polymerase-chain-reaction (PCR)-based assay. LOH of the M6P/IGF2R gene in the primary HCCs was detected in 10 of 22 informative cases (45%). In five of these 10 cases (50%), LOH was detected in cirrhotic lesions adjacent to the HCCs. The allelic loss patterns of M6P/IGF2R in liver cirrhosis (LC) were identical to those in the corresponding HCC, suggesting that HCC could develop from one of the cells in which M6P/IGF2R had been lost. Furthermore, LOH of the p53 gene in HCC was detected in 10 (43%) of 23 informative cases, and p53 loss in cirrhotic foci adjacent to HCC was shown in one of the 10 cases (10%). The pattern of allelic loss of the p53 gene in the cirrhotic foci was identical with that in the corresponding tumor. The LOH of the M6P/IGF2R and p53 genes occurred independently in HCCs. LOH of the M6P/IGF2R locus was a relatively frequent and possibly early event in hepatocarcinogenesis, and LOH of the M6P/IGF2R gene and LOH of the p53 gene occurred independently.

Effective suppression of HIV-1 gene expression by a mammalian tRNA 3' processing endoribonuclease and external guide sequence oligozymes

We examined the suppression of virus expression by cleaveage of the HIV-1 RNA gene using a mammalian tRNA 3' processing endoribonuclease and an External Guide Sequence Oligozyme (EGS) in vivo. We constructed an EGS expression vector that used the tRNA(met) promoter as an expression cassette for EGS. The EGS expression vector was targeted to the upstream region of gag, region. The EGS expression vector was co-transfected into COS cells with the HIV-1 gene plasmid vector. As compared with the EGS non-expressing cells and the EGS expressing cells, the EGS expressing cells with the targeted gag start codon had a clearly decreased amount of the HIV-1 gag p24 protein. The EGS expressing cells with the targeted gag start codon showed effective suppression of HIV-1 gene expression. Thus, these studies describe novel gene targeting agents for the inhibition of gene expression and antiviral activity.

Effects of itopride hydrochloride on the delayed rectifier K+ and L-type CA2+ currents in guinea-pig ventricular myocytes

The effects of itopride hydrochloride, a new drug used to regulate motility in the gastrointestinal tract, on the delayed rectifier K+ current (I(K)) and the L-type Ca2+ current (I(Ca)) were evaluated in guinea-pig ventricular myocytes at concentrations of 1, 10 and 100 microM to determine whether the drug has a proarrhythmic effect through blockade of I(K). Itopride did not affect I(K) at concentrations of 100 microM or less, and no significant effects of 1, 10 or 100 microM itopride were observed on the inward rectifier K+ current (I(K1)) responsible for the resting potential and final repolarization phase of the action potential. We next investigated the effects of itopride on L-type Ca2+ current (I(Ca)). Significant inhibition of I(Ca) was observed at itopride concentrations greater than 10 microM. These results suggested that itopride hydrochloride has an inhibitory effect on I(Ca) at concentrations much higher than those in clinical use.

Influence of angiotensin II type 1 receptor polymorphism on hypertension in patients with hypercholesterolemia

Essential hypertension results from the combined influence of environmental and genetic factors. The relationship between angiotensin II type 1 receptor (AT(1)) A-C(1166) polymorphism and essential hypertension is controversial. Because it is accepted that high concentration of serum cholesterol is one of risk factors of atherosclerosis, we investigated the influence of the AT(1) A-C(1166) polymorphism on hypertension in patients with hypercholesterolemia. A total of 131 hypertensive, 97 borderline, and 175 normotensive subjects were enrolled in this study. We selected hypercholesterolemic subjects on the condition that their serum concentration of total cholesterol was >220 mg/dl, and obtained 55 hypertensive, 24 borderline, and 52 normotensive subjects with hypercholesterolemia. There were no significant differences in the genotype nor allele frequency between hypertensive and normotensive subjects in the overall population. However, the presence of the C allele of the AT(1) gene has a tendency to increase the value of systolic blood pressure not only in subjects with hypercholesterolemia but also in the overall population. Furthermore, we found a significant relationship between the AT(1) polymorphism and hypertension in subjects with hypercholesterolemia; i.e., the frequency of the C allele of the AT(1) gene was significantly higher in hypertensives than in normotensives (P<0.005). These results suggested that high concentration of total cholesterol was an important risk factor to the occurrence of essential hypertension for patients who carried the C allele of the AT(1) gene.

Histomorphometric analysis of age changes in the human inferior alveolar artery

Angiography is often used to investigate age-related changes in the inferior alveolar artery, the major nutrient artery of the mandible. Although histological examinations have been made from several viewpoints, e.g. age change, pathogenesis of osteoradionecrosis, and relation to tooth extraction, these studies have used a limited number of samples and simple histometric methods. The purpose here was to describe histopathological and histomorphometric age-related changes, and to investigate the relation between dentate status and the histomorphometry of the artery. Inferior alveolar arteries from 162 autopsy cases (age range 3-86 years) were examined histometrically with a mathematically standardized method. Histologically, there was diffuse fibrous intimal thickening, but no atheroma formation. Histometric analyses revealed a very gradual increase in both the radius of the artery and the thickness of the media with age, but the luminal radius did not correlate with age. Intimal thickness increased exponentially with age with very different features from those of the increase in the media. The relative radius of the lumen decreased with age after the sixth decade; this is thought to be an index for senile changes in the artery. Among the variables of arterial architecture examined, no particular difference was found between the dentate and non-dentate cases in the molar region.

Effect of SMP-300, a new Na+/H+ exchange inhibitor, on myocardial ischemia and experimental angina models in rats

We evaluated the effects of SMP-300 (N-(aminoiminomethyl)-11-chloro-5,6,7,8-tetrahydro-8-oxo-4H-pyrrolo[3,2,1-kl][1]benzazocine-2-carboxamide monomethanesulfonate monohydrate), a newly synthesized compound, on Na+/H+ exchange activity in rat cardiomyocytes and on other ion transporters, channels and receptors. We also investigated the protective effects of SMP-300 in isolated ischemic rat hearts and rat isoproterenol- or vasopressin-induced experimental angina models. SMP-300 concentration-dependently inhibited recovery from acidosis in rat myocytes, and its IC50 for Na+/H+ exchange was 6 nM. In comparison, its IC50s for Na+/Ca2+ exchange and for the Na+ channel were >1000 nM, and those for other channels or receptors tested were >10,000 nM. In rat isolated perfused hearts, SMP-300 (10(-8)-10(-7) M), administered only at preischemia and not during reperfusion, significantly improved the postischemic recovery of cardiac function. SMP-300 (0.03-0.3 mg/kg, i.v.) or 5-(N-ethyl-N-isopropyl)-amiloride (1 mg/kg, i.v.) prevented the isoproterenol-induced ST-segment depression in the ECG of anesthetized rats, in a dose-dependent manner. SMP-300 (0.1 mg/kg, i.v.) and 5-(N-ethyl-N-isopropyl)-amiloride (1 mg/kg, i.v.) also inhibited the vasopressin-induced ST-segment depression in the ECG of anesthetized rats. This is the first report presenting the protective effect of Na+/H+ exchange inhibitors on isoproterenol- or vasopressin-induced ECG changes in rats, providing the future perspective of SMP-300, a potent Na+/H+ exchange inhibitor, as an anti-anginal drug.

Reduction of myocardial infarct size by SM-20550, a novel Na(+)/H(+) exchange inhibitor, in rabbits

The effects of N-(aminoiminomethyl)-1, 4-dimethyl-1H-indole-2-carboxamide methanesulfonic acid (SM-20550), a novel potent Na(+)/H(+) exchanger, and nicorandil, a K(+) channel opener with nitrate-like activity, were studied in a myocardial ischemia and reperfusion injury model. Anesthetized rabbits underwent occlusion of the coronary artery (30 min) followed by reperfusion (5 h). Intravenous administration of SM-20550 before ischemia reduced the infarct size by approximately 30-70% in a dose-dependent manner, with a significant reduction in serum creatine phosphokinase activity. Similarly, intravenous administration of nicorandil before ischemia reduced the infarct size by 33% with a significant reduction in serum creatine phosphokinase activity. Moreover, intravenous administration of SM-20550 after ischemia resulted in a significant, approximately 20-40% reduction in the infarct size, but the administration of nicorandil after ischemia did not reduce the infarct size. These results indicate that SM-20550 reduced myocardial necrosis when administered either before or after ischemia.

Higher osteoclastic demineralization and highly mineralized cement lines with osteocalcin deposition in a mandibular cortical bone of autosomal dominant osteopetrosis type II: ultrastructural and undecalcified histological investigations

In this study we report on histological and ultrastructural investigations of the mandibular cortical bone in a case of autosomal dominant osteopetrosis type II complicated by mandibular osteomyelitis. Histologically, there was a marked increase in the number and size of osteoclasts on the inner bone surface. An undecalcified preparation showed a pair of deeply stained (highly demineralized) and stain-phobic (highly mineralized) layers on the bone surface just beneath the osteoclasts. The layers were incorporated into the bone matrix during the remodeling process as thickened cement lines. A contact microradiogram of the cortical bone revealed highly mineralized layers at the cement lines, which were closely correlated with immunohistochemical evidence of deposition of osteocalcin at the thickened cement lines. Ultrastructural examination showed that the osteoclasts had a typical clear zone, but they were deficient in ruffled border formation and had numerous lysosomal vacuoles containing dense substances. An electron-dense amorphous material layer was present on the bone surface just beneath the osteoclasts as well as at the cement lines. The layer was partly composed of a short fibrillar material, and it partially revealed the lamellar structure. Consequently, an osteoclastic malfunction might be primarily involved in the process of bone matrix resorption rather than demineralization, resulting in higher demineralization and abnormal material deposition on the bone surface and at the cement lines. Furthermore, evidence of active osteoclastic bone resorption with a brush border formation at the bone involved in the inflammatory lesion in this case suggests that the osteoclastic malfunction is influenced and recovered by a microenvironment such as inflammatory cytokines.

Prevalence of hepatitis G virus (HGV) infection in an endemic area of hepatitis C virus (HCV) infection

BACKGROUND/AIMS

We investigated the prevalence of hepatitis G virus infection among inhabitants of a hepatitis C virus endemic area.

METHODOLOGY

Two hundred and eighty-eight inhabitants, who underwent medical examinations for health screening, were enrolled in this epidemiological study. HGV RNA and HCV RNA were detected by polymerase chain reaction. We also examined anti-HGV envelope protein (E2) antibodies in all serum samples.

RESULTS

In these 288 inhabitants, we found anti-HCV antibodies (HCV-Ab) and HCV RNA in 28.5% and 17.4%, respectively. HGV RNA and anti-HGV E2 were detected in 9 (3.1%) and 16 (5.5%), respectively. One patient was positive for both HGV RNA and anti-HGV E2. The exposure rate, expressed as the percentage of people with HGV RNA and/or anti-HGV E2, was 8.3%, which was significantly lower than the incidence of positive HCV-Ab. Of the 24 patients with HGV RNA and/or anti-HGV E2, 15 (62.5%) were positive for HCV-Ab, of those HCV RNA was detected in 9 (37.5%). Further, we found a higher prevalence of HGV exposure in patients with HCV-Ab than in those without (8.3% vs. 4.4%).

CONCLUSIONS

HGV infection was not identical to the epidemic hepatitis C virus infection among inhabitants of this town, suggesting that hepatitis C virus might be less infectious than hepatitis C virus.

alpha-fluoromethylhistidine depletes histamine from secreting but not from non-secreting rat stomach ECL cells

Histamine in the oxyntic mucosa of the rat stomach occurs in mast cells (10%) and ECL cells (90%). Unlike the mast cells, the ECL cells operate under the control of gastrin. alpha-Fluoromethylhistidine, an irreversible inhibitor of the histamine-forming enzyme, histidine decarboxylase depletes ECL-cell but not mast-cell histamine. This report shows that the effectiveness by which histidine decarboxylase inhibition depletes ECL-cell histamine depends on the rate of histamine secretion. Rats received alpha-fluoromethylhistidine by continuous subcutaneous infusion for 24 h. Maximally effective doses (>/=3 mg/kg/h) inhibited histidine decarboxylase and reduced oxyntic mucosal histamine in fed rats by 80-90%. In fasted rats, the reduction was 50%. alpha-Fluoromethylhistidine greatly reduced the number of histamine-immunoreactive ECL cells (immunocytochemistry) and of secretory vesicles in the ECL cells (electron microscopy) in fed but not in fasted rats. The half-life of oxyntic mucosal histamine (determined upon histidine decarboxylase inhibition) was 2.6 h in fed rats and 19.4 h in fasted rats. The amount of histamine secreted in response to gastrin (monitored by gastric submucosal microdialysis) was greatly reduced by alpha-fluoromethylhistidine in fed rats but not in fasted rats. ECL cells were isolated from rat stomach by elutriation (80% purity). Their histamine content was determined after culture, with or without alpha-fluoromethylhistidine, in the presence of varying concentrations of gastrin. In a medium containing 10 nM gastrin, ECL cells responded to a maximally effective concentration of alpha-fluoromethylhistidine (0.1 nM) with 80% reduction in histamine content. In the absence of gastrin, ECL cells responded to alpha-fluoromethylhistidine with 45% reduction of histamine; the releasable histamine pool was unaffected. In conclusion, the combination of histidine decarboxylase inhibition and a high rate of histamine secretion will promptly exhaust the ECL-cell histamine pool, while histidine decarboxylase inhibition and a low secretion rate will affect the histamine pool much less.

Increased fractal complexity of the epithelial-connective tissue interface in the tongue of 4NQO-treated rats

The effect of the carcinogen 4-nitroquinoline 1-oxide (0.001% in drinking water) on the irregularity of the epithelial connective tissue interface (ECTI) of the ventral surface of the tongue was quantified in Dark Agouti and Wistar Furth rats. Histological tongue sections stained with the Azan-Mallory method were digitised (111 images, resolution 1 pixel = 3.1 microns), and the limit between epithelium and stroma of the ventral surface was extracted and analysed using a fractal geometry technique (local connected dimension). The results showed that although none of the images included carcinomas on the ventral surface of the tongue (all cases had other oral carcinomas), the epithelial profiles of the treated cases showed a statistically significant increase in irregularity when compared to controls. Canonical discriminant analysis of the parameters describing the irregularity of the ECTI classified 81.1% of the images in the original groups (treated or control). Fractal analysis is capable of detecting subtle architectural changes in the oral epithelium of the rat occurring after exposure to the carcinogen, even when full malignant transformation has not yet taken place. Fractal analysis, which may prove useful for monitoring the progression of carcinogenesis in this animal model, is a morphometrical parameter in the diagnosis of oral epithelial dysplasia.

Chemopreventive effects of coumaperine from pepper on the initiation stage of chemical hepatocarcinogenesis in the rat

This study was designed to investigate the chemopreventive action of three natural products, coumaperine, aurapten and an extract from rosemary, against the initiation stage of rat hepato-carcinogenesis. Coumaperine has been isolated from white pepper as a naturally occurring antioxidative agent, but its potential modifying effects on carcinogenesis remain unclear. In experiment 1, a modification of the model developed by Tsuda et al. was applied, with assessment of numbers and areas of induced glutathione S-transferase placental form (GST-P)-positive hepatocellular foci in male F344 rats. Coumaperine, aurapten and the extract from rosemary were administered i.g. at 100 mg / kg / day once daily for 5 days with initiation by diethylnitrosamine (DEN) on day 4 (20 mg / kg, i.p.). Numbers and areas of GST-P-positive foci in each group given test chemicals tended to be decreased as compared to the vehicle control group values, significance being achieved for number with coumaperine. Experiment 2 was planned to investigate the mechanism of the inhibitory effects of coumaperine. Livers at 8 h after initiation by DEN were examined with coumaperine administered at 100 mg / kg / day once daily for 3 days. Proliferating cell nuclear antigen (PCNA)-positive cells tended to be decreased as compared to the vehicle control, but no effects on apoptosis or cytochrome P-450 (CYP) 2E1 expression were apparent. Our results suggest that coumaperine provides protection against initiation of hepatocarcinogenesis, and that this is related to inhibition of cell proliferation.

Possible rare involvement of O6-methylguanine formation as a significant mutational factor in mouse urinary bladder carcinogenesis models

O6-methylguanine is known as one of the major premutagenic lesions in the human and rodent carcinogenesis process. O6-methylguanine-DNA methyltransferase (MGMT), which repairs methylated guanine bases, might prevent the G:C to A:T transition, and transgenic mice carrying this MGMT gene have been reported to be less sensitive to the carcinogenicity of certain alkylating agents. Here we utilized MGMT transgenic mice to assess the significance of O6-methylguanine formation during urinary bladder carcinogenesis. In experiment 1, 100 and 60 ppm N-butyl-N(4-hydroxybutyl)nitrosamine was given for 20 weeks to transgenic and non-transgenic mice in their drinking water. The incidences of urinary bladder carcinomas were not different between transgenic mice and non-transgenic mice. The mutational spectrum of the p53 gene was evaluated by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and direct sequencing. The pattern of p53 mutations of transgenic and non-transgenic mice did not differ, and the frequencies of mutations were 40% and 42%, respectively. G:C to A:T transition mutations were particularly infrequent (1 of 14 mutations, 7%). In experiment 2, N-methyl-N-nitrosourea, which might induce O6-methylguanine in affected alleles, was given once a week, 3 times (total 5 mg) by direct instillation into the urinary bladder through an abdominal incision. No significant neoplastic lesions were detected, although the experiment was limited by severe toxicity of the treatment. p53 immunostaining was done and there was no difference in transgenic and non-transgenic mice. These results suggest that O6-methylguanine formation might not be a significant mutational factor in these mouse urinary bladder carcinogenesis models.

Anaesthetic agents inhibit gastrin-stimulated but not basal histamine release from rat stomach ECL cells

By mobilizing histamine in response to gastrin, the ECL cells in the oxyntic mucosa play a key role in the control of the parietal cells and hence of gastric acid secretion. General anaesthesia suppresses basal and gastrin- and histamine-stimulated acid secretion. The present study examines if the effect of anaesthesia on basal and gastrin-stimulated acid secretion is associated with suppressed ECL-cell histamine secretion. A microdialysis probe was implanted in the submucosa of the ventral aspect of the acid-producing part of the stomach (32 rats). Three days later, ECL-cell histamine mobilization was monitored 2 h before and 4 h after the start of intravenous infusion of gastrin (5 nmol kg(-1) h(-1)). The rats were either conscious or anaesthetized. Four commonly used anaesthetic agents were given 1 h before the start of the experiments by intraperitoneal injection: chloral hydrate (300 mg kg(-1)), pentobarbitone (40 mg kg(-1)), urethane (1.5 g kg(-1)) and a mixture of fluanisone/fentanyl/midazolam (15/0.5/7.5 mg kg(-1)). In a parallel series of experiments, basal- and gastrin-induced acid secretion was monitored in six conscious and 25 anaesthetized (see above) chronic gastric fistula rats. All anaesthetic agents lowered gastrin-stimulated acid secretion; also the basal acid output was reduced (fluanisone/fentanyl/midazolam was an exception). Anaesthesia reduced gastrin-stimulated but not basal histamine release by 55 - 80%. The reduction in gastrin-induced acid response (70 - 95%) was strongly correlated to the reduction in gastrin-induced histamine mobilization. The correlation is in line with the view that the reduced acid response to gastrin reflects impaired histamine mobilization. Rat stomach ECL cells were purified by counter-flow elutriation. Gastrin-evoked histamine mobilization from the isolated ECL cells was determined in the absence or presence of anaesthetic agents in the medium. With the exception of urethane, they inhibited gastrin-evoked histamine secretion dose-dependently, indicating a direct effect on the ECL cells. Anaesthetized rats are widely used to study acid secretion and ECL-cell histamine release. The present results illustrate the short-comings of such an approach in that a number of anaesthetic agents were found to impair not only acid secretion but also the secretion of ECL-cell histamine - some acting in a direct manner.

SM-20550, a new Na+/H+ exchange inhibitor and its cardioprotective effect in ischemic/reperfused isolated rat hearts by preventing Ca2+-overload

We investigated the effect of a newly synthesized compound, SM-20550 [N-(aminoiminomethyl)-1,4-dimethyl-1H-indole-2-carboxamide methanesulfonic acid] on Na+/H+ or Na+/Ca2+ exchange activity in rat cardiomyocytes, and on radioligand binding with several channels or receptors in membrane preparations, and ischemia/reperfusion injury in isolated perfused rat hearts. In myocytes, SM-20550 concentration-dependently inhibited the recovery from acidosis induced by an NH4Cl prepulse in HCO3(-)-free solution. Its IC50 was 10(-8) M, which was 10 times lower than that of ethylisopropyl amiloride (EIPA). SM-20550 (10(-6) M) did not affect the Na+-dependent Ca2+ influx (Na+/Ca2+ exchange activity) in cardiomyocytes. In the radioligand binding assay, SM-20550 did not have affinity for K+ channel, beta-adrenoceptor, adenosine, angiotensin, or endothelin receptors, and had low affinity for Na+ and Ca2+ channels and alpha-adrenoceptors, only at the concentrations of 10(-6)-10(-5) M. In perfused hearts exposed to 40 min of global ischemia and 20 min of reperfusion, SM-20550 (10(-8)-10(-7) M) significantly reduced the elevation of left ventricular end-diastolic pressure during reperfusion, improved the postischemic recovery of developed pressure, and prevented coronary perfusion pressure increase after reperfusion. Furthermore, SM-20550 reduced creatine phosphokinase release during reperfusion and prevented the abnormal gain of tissue Na+ and Ca2+ at the end of reperfusion. These results suggest that SM-20550 is a potent, highly specific Na+/H+ exchange inhibitor, which exerts a protective effect against myocardial ischemia/reperfusion injury. In addition, our data strongly support the hypothesis that Na+/H+ exchange plays an important role in the development of postischemic cardiac dysfunction, most likely by inducing Na+ and Ca2+ overload.

Long-lasting cholecystokinin(2) receptor blockade after a single subcutaneous injection of YF476 or YM022

Histamine-forming ECL cells in the rat stomach operate under the control of gastrin. They represent a convenient target for studying cholecystokinin-B/gastrin (CCK(2)) receptor antagonists in vivo. We examined the effectiveness and duration of action of two CCK(2) antagonists, YM022 and YF476, with respect to their effect on ECL-cell histidine decarboxylase (HDC) activity in the rat. Oral administration of subcutaneous deposition of YF476 or YM022 reduced the HDC activity. The maximum/near-maximum dose for both drugs and for both modes of administration was 300 micromol kg(-1) (effects measured 24 h after dose). At this dose and time the serum concentration of YF476 was 20 - 40 nmol l(-1). The dose 300 micromol kg(-1) was used in all subsequent studies. A single subcutaneous injection of YF476 inhibited the HDC activity for 8 weeks. The circulating concentration of YF476 remained high for the same period of time (>/=15 nmol l(-1)). Subcutaneous YM022 suppressed the HDC activity for 4 weeks. A single oral dose of YF476 or YM022 inhibited the HDC activity for 2 - 3 days. Chronic gastric fistula rats were used to study the effect of subcutaneous YF476 on gastrin-stimulated acid secretion. A single injection of YF476 prevented gastrin from causing an acid response for at least 4 weeks (the longest time studied). We conclude that a single subcutaneous injection of 300 micromol kg(-1) YF476 causes blockade of CCK(2) receptors in the stomach of the rat for 8 weeks thus providing a convenient method for studies of the consequences of long-term CCK(2) receptor inhibition.

Host genes controlling the susceptibility and resistance to squamous cell carcinoma of the tongue in a rat model

Development of tongue carcinoma (TC) in rats by 4-nitroquinoline 1-oxide (4NQO), a potent carcinogen, is under host genetic control. The inbred Dark-Agouti (DA) strain rats showed a much higher susceptibility to TC than the Wistar-Furth (WF) strain. The author's previous study on crosses between two strains postulated a susceptibility gene in DA and a resistance gene in WF rats. This hypothesis was confirmed by the genetic analysis of the backcrosses to either parent and F2 with a simple sequence repeat polymorphism analysis. In the crosses between the DA and WF strains of rats, two major independently segregating host loci that influenced the cancer development by application of 4NQO positively or negatively were identified and mapped. DA rats had a semidominant susceptibility gene, Stc1, closely linked with D19Mit9 on chromosome 19, which was on the segment syntenic to human chromosome 16. In contrast, WF rats had a semidominant resistance gene, Rtc1, closely linked with D1Rat320 on chromosome 1, which is syntenic to human chromosome 11. The presence of other susceptibility and resistance genes on some chromosomes of both DA and WF rats was suspected, and they will be clarified in the near future. These findings provide powerful evidence that chemically induced tongue carcinogenesis is a multigenetic event.

Effects of trimebutine maleate on delayed rectifier K+ currents in guinea-pig ventricular myocytes

The effects of trimebutine maleate, a drug commonly used to regulate motility in the gastrointestinal tract, on the delayed rectifier K+ current (I(K)) were evaluated in guinea-pig ventricular myocytes to determine whether the drug has a proarrhythmic effect through blockade of I(K). Trimebutine decreased I(K) in a concentration-dependent manner. To investigate the effects of trimebutine on two components of I(K) (I(Kr) and I(Ks); rapidly activated and slowly activated components, respectively), we performed the envelope-of-tails test. Trimebutine-sensitive I(K) was determined by digital subtraction of I(K) during exposure to trimebutine from control I(K) for each duration of the test pulse over the range 50 ms-2 s. The ratio of deltaI(K,tail)/deltaI(K) plotted against pulse duration for trimebutine-sensitive I(K) gradually decreased to a steady-state value as the duration of the test pulse was lengthened. This finding suggested a weak inhibitory effect of trimebutine on both I(Kr) and I(Ks). The effects of trimebutine on the inward rectifier K+ current (I(K1)) responsible for the resting potential and final repolarization phase of the action potential were investigated by applying voltage clamp ramps over a broad range of potentials. No significant effects were observed at 10 or 100 microM. We next investigated the effects of the drug on the L-type Ca2+ current (I(Ca)). Significant inhibition of I(Ca) was observed at trimebutine concentrations greater than 10 microM. These results suggested that trimebutine maleate has weak inhibitory effects on I(Kr), I(Ks) and I(Ca) at concentrations much higher than those in clinical use.