Intrasplenic autograft of testicular tissue in rats

Intrasplenic heterotransplantation of infantile testis is a conventional method to produce testicular tumors in adult castrated rodents. To avoid possible immunological interference in the tumorigenic process in allografted testis, the parenchyma of testis of Wistar strain rats aged 7 weeks was injected into the spleen of the same rat after bilateral gonadectomy. In 17 of 20 animals testicular neoplasms, resembling gonadal stromal cell tumors in human, developed from the intrasplenic gonadal tissue in the 14th month following transplantation. This autografting technique is feasible to induce testicular neoplasms in granulosa cell tumor category in high incidence, and thus deserves further attention.

[Long-term follow up of QRS axis deviation]

It has been already described that the average axis of QRS complex is deviated by aging as well as various diseases, such as ventricular overload or bundle branch block. In this study, we first tested the hypothesis that the extra-cardiac factor changes with aging, such as the body shape or diaphragm position, which are represented by body weight (WT) and/or cardiac-thoracic ratio (CTR), are the main cause of QRS axis deviation. In 28 cases including 1 right (RAD) and 27 left axis deviation (LAD) patients whose QRS axis have been deviated during observed periods, WT and X-ray CTR were compared to the degree of axis deviation. Unfortunately no clear relationship was found among these parameters. On the other hand, in 8 cases out of 27 LAD patients, confirmed or suspected left anterior hemiblock (LAH) was found by vector electrocardiogram. Pathological studies showed that the degeneration of the stimulation pathway occurred with aging and it caused the bundle branch block. Therefore, we conclude that the degenerative change in left anterior stimulation pathway by aging should be, at least, one of the cause of the QRS axis deviation.

Modulation of cancer chemotherapy by green tea

Biochemical modulation has played an important role in the development of cancer chemotherapy. We have directed our attention to the intake of common beverages and investigated the effects of green tea and tea components on the antitumor activity of doxorubicin. We carried out the combined treatment of toxorubicin and green tea on Ehrlich ascites carcinoma tumor-bearing mice. The oral administration of green tea enhanced 2.5-fold the inhibitory effects of doxorubicin on tumor growth. The Doxorubicin concentration in the tumor was increased by the combination of green tea with doxorubicin. In contrast, the increase in doxorubicin concentration was not observed in normal tissues after green tea combination. Furthermore, the enhancement of antitumor activity of doxorubicin induced by green tea was observed in M5076 ovarian sarcoma, which has low sensitivity to doxorubicin. These results suggest that drinking green tea can encourage cancer chemotherapy and may improve the quality of life of clinical patients.

Intrasplenic grafting of ovarian tissue containing 7, 12-dimethylbenz[a]anthracene

To produce malignant granulosa cell tumors, ovarian tissue containing 7,12-dimethylbenz[a]anthracene (DMBA) was autografted in the spleen of 20 castrated rats. Adenocarcinoma developed in 8 rats within 6 months from the transplantation. Granulosa cell tumor arose from the intrasplenic graft, in 6 rats at the 14th month. The neoplastic cells were diffusely arranged in sheet showing focal luteinization. In 3 cases extrasplenic spreads were found on the peritoneal surface. Since malignant ovarian tumors seldom develop by intrasplenic grafting alone, the DMBA treatment may contribute to the occurrence of malignant granulosa cell tumor.

Toxic interactions between disopyramide and propranolol in chick embryos

The toxic interaction between disopyramide and propranolol were studied in chick embryos. Fertilized eggs of White Leghorns were incubated and investigated. Disopyramide with and without propranolol was injected into the air sac of a fertilized egg on the 16th day of incubation. Electrocardiograms (ECGs) were recorded 0 to 60 min after the injection. After each drug injection alone, the heart rate was not different compared with control. However, the heart rate was significantly decreased by combination with disopyramide and propranolol. In addition, arrhythmia was produced by disopyramide 1.0 mg/egg alone and in combination with propranolol. These findings indicate that the interaction between disopyramide and propranolol has a marked influence on the heart rate in chick embryos.

What role does Helicobacter pylori play in gastric cancer?

Several lines of evidence support an association between Helicobacter pylori infection and gastric cancer. The natural history of H. pylori-associated gastritis is inexorable progression ultimately leading to gastric atrophy. In general, this process requires between 20 and 40 years to complete. Atrophic gastritis is widely considered to be a precursor lesion of the intestinal type of gastric cancer. Moreover, areas with a high prevalence of H. pylori infection also have a high prevalence of gastric cancer. Strong evidence from three prospective studies shows the risk of gastric cancer to be increased fourfold in H. pylori-positive persons. Several retrospective studies have also confirmed that H. pylori infection is associated with development of gastric cancer, especially in the younger generation, early gastric cancer, and noncardiac gastric cancer. H. pylori alone is not likely responsible for gastric cancer. Rather, it may provide a suitable environment, including chronic gastritis and intestinal metaplasia, for neoplastic change. Recognition of an association between H. pylori infection and gastric cancer has led to a major shift in emphasis on the cause of the disease. Research into H. pylori has focused attention on the importance of chronic inflammation and impaired host defense mechanisms as factors in the development of gastric cancer. H. pylori infection leads to changes in many factors that are important to the pathogenesis of gastric cancer, including vitamin C content of gastric juice, reactive oxygen metabolites, and epithelial cell proliferation. Eradication of the organism may reverse these changes. Therefore, eradication of H. pylori in infected persons might be a route to preventing gastric cancer, although many questions still remain as to the effectiveness of this strategy.

Differential release of endotoxin from Pseudomonas aeruginosa treated with beta-lactam antibiotics and its effect on the lethal activity

The relationship between the level of endotoxin released from Pseudomonas aeruginosa by exposure to beta-lactam antibiotics and the lethal activity against D-galactosamine (D-GalN)-sensitized mice was examined. In vitro treatment of P. aeruginosa with imipenem (IPM) exclusively caused low-level release of free endotoxin, which was not lethal for D-GalN-sensitized mice. Treatment with other beta-lactam antibiotics, such as ceftazidime (CAZ), meropenem (MEPM) and cefozopran (CZOP) caused high-level release of free endotoxin and it exhibited the lethal action against D-GalN-sensitized mice. This study demonstrated close association of free endotoxin released by antibiotic treatment with the lethal activity.

Essential roles of the winged helix transcription factor MFH-1 in aortic arch patterning and skeletogenesis

Mesenchyme Fork Head-1 (MFH-1) is a forkhead (also called winged helix) transcription factor defined by a common 100-amino acid DNA-binding domain. MFH-1 is expressed in non-notochordal mesoderm in the prospective trunk region and in cephalic neural-crest and cephalic mesoderm-derived mesenchymal cells in the prechordal region of early embryos. Subsequently, strong expression is localized in developing cartilaginous tissues, kidney and dorsal aortas. To investigate the developmental roles of MFH-1 during embryogenesis, mice lacking the MFH-1 locus were generated by targeted mutagenesis. MFH-1-deficient mice died embryonically and perinatally, and exhibited interrupted aortic arch and skeletal defects in the neurocranium and the vertebral column. Interruption of the aortic arch seen in the mutant mice was the same as in human congenital anomalies. These results suggest that MFH-1 has indispensable roles during the extensive remodeling of the aortic arch in neural-crest-derived cells and in skeletogenesis in cells derived from the neural crest and the mesoderm.

Cardiac sympathetic neuropathy and effects of aldose reductase inhibitor in streptozotocin-induced diabetic rats

Cardiac autonomic neuropathy can be a cause of sudden death in patients with diabetes mellitus. Clinical evaluation methods for diabetic cardiac sympathetic neuropathy have not been established. Using 125I-metaiodobenzylguanidine (MIBG) and streptozotocin (STZ)-induced diabetic rats, we evaluated cardiac sympathetic neuropathy and the effects of aldose reductase inhibitor (ARI).

METHODS

Myocardial MIBG uptake was measured 4 hr after injection in the following groups: control rats, rats treated with insulin or ARI (epalrestat, 100 mg/kg/day) from immediately to 4 wk after STZ injection and rats treated with insulin or ARI from 4-8 wk. Myocardial MIBG distribution and norepinephrine content were evaluated in the control and diabetic rats with or without ARI therapy started immediately after STZ injection.

RESULTS

Myocardial MIBG uptake was significantly lower in diabetic rats than in control rats; the reduction was marked in the subendocardial myocardium. Myocardial norepinephrine content was increased significantly in diabetic rats compared with control rats. Decreased MIBG uptake and increased norepinephrine content in diabetic myocardium were completely prevented by insulin therapy started immediately after STZ injection and partially, but significantly, by ARI administered from immediately after STZ injection. Heterogeneous MIBG distribution also disappeared with the ARI therapy. In contrast, diabetic rats treated with insulin or ARI therapy started 4 wk after STZ injection showed no improvement in MIBG uptake.

CONCLUSION

These results suggest that MIBG abnormalities observed in diabetic rats may reflect diabetic cardiac sympathetic neuropathy independently of cardiomyopathy, nephropathy or coronary heart disease secondary to diabetes and that MIBG imaging may be useful for clinical assessment of cardiac sympathetic neuropathy.

Activation and repression of the activity of a lead ribozyme by the combination of Pb2+ and Mg2+

The effect of Pb2+ and Mg2+ on the activity of a lead ribozyme with modified sequences has been studied. At low Pb2+ concentrations, cleavage at a previously reported site (site a) is observed. At higher Pb2+ concentrations, cleavage at a new site (site b) adjacent to site a is observed, while the cleavage at site a is repressed. On the addition of a certain amount of Mg2+, the cleavage at site a is enhanced by almost fourfold, while the cleavage at site b is repressed. Further addition of Mg2+ represses the cleavage at both sites. CD analysis indicates that the structure and stability of the lead ribozyme change depending on the metal conditions. Activation and repression of the activity by the combination of Pb2+ and Mg2+ are rationalized by considering that the two metals compete with each other for binding at two metal-binding sites.

Comparison of [123I]metaiodobenzylguanidine kinetics with heart rate variability and plasma norepinephrine level

BACKGROUND

[123I]Metaiodobenzylguanidine (MIBG) imaging has been used to assess cardiac sympathetic nerve abnormalities. We evaluated the clinical significance of myocardial MIBG imaging as a measure of cardiac sympathetic nervous system function by comparing it to heart rate variability and plasma norepinephrine level.

METHODS AND RESULTS

In 211 subjects, we analyzed heart rate variability with 24-hour electrocardiography, performed scintigraphy with MIBG, and measured plasma norepinephrine levels. Time and frequency domain measures of heart rate variability were calculated with the Marquette heart rate variability program (Marquette Electronics, Milwaukee, Wis.). Early and late myocardial MIBG uptakes were measured at 15 and 150 minutes after injection, respectively. MIBG clearance rate from the heart and heart-to-lung and heart-to-mediastinum ratios of MIBG activities were calculated. On the whole, heart rate variability, including low-frequency power, correlated positively, but modestly so, with late MIBG uptake and negatively with MIBG clearance rate. The plasma norepinephrine level correlated negatively with late MIBG uptake and with heart rate variability, including low-frequency power, and positively with MIBG clearance rate. Similar correlations were also observed in patient subgroups with coronary artery disease, diabetes mellitus, and renal failure, but these correlations were weak (R2 < 0.5).

CONCLUSIONS

Increased cardiac sympathetic nervous system activity may be associated with increased myocardial MIBG clearance and decreased heart rate variability, including low-frequency power. Because these associations were not strong, however, the combination of heart rate variability with MIBG may allow an interactive assessment of the cardiac autonomic nervous system.

Loss of arterial dilation in the reendothelialized area of the flow-loaded rat common carotid artery

We have investigated regenerated endothelial cells and their possible contribution to arterial dilation in response to increased blood flow in rat common carotid artery (CCA). After endothelial denudation using a balloon catheter in the left CCA, an arteriovenous shunt was constructed between the left CCA and the left external jugular vein at 20 mm distal from the orifice in the denuded group. Animals that were given the arteriovenous shunt without denudation were used to form the nondenuded group. The blood flow rate in the left CCA was increased by sixfold after operation in the denuded group. We observed that endothelial cells were gradually regenerated from the orifice to the distal area and that the reendothelialized area after 4 to 8 weeks was approximately one third of the left CCA (5.31 +/- 1.49 mm at 4 weeks, 5.47 +/- 1.56 mm at 8 weeks). In the reendothelialized area of the left CCA after 4 to 8 weeks, the lumen diameter was significantly smaller than that of the nondenuded group and showed no significant difference from age-matched nonsurgical animals. The intimal and medial thickening, which would result in arterial stenosis in the reendothelialized area, was not observed in the denuded group, although the denuded control showed significant intimal thickening. From these results, we conclude that regenerated endothelial cells reduce intimal thickening but do not respond to increased blood flow to dilate the artery.

Retinal toxicity of nitric oxide released by administration of a nitric oxide donor in the albino rabbit

PURPOSE

Nitric oxide (NO), which has been identified as an endothelium-derived relaxing factor, might be involved in regulation of retinal circulation and intraocular pressure. Recently, it was suggested that NO might also be related to neuronal excitotoxicity mediated by the N-methyl-D-aspartate receptor and to the pathologic changes induced by some kinds of uveitis. However, ocular toxicity of NO released by an NO donor has not been clearly demonstrated. In the current study, NO neurotoxicity in the retina was investigated.

METHODS

S-nitroso-N-acetyl-DL-penicillamine (SNAP, 200 nmol) was injected into the vitreous of albino rabbits as an NO donor. The changes of retinal function were evaluated at 1, 2, and 3 hours and 1 and 4 weeks after SNAP injection, using electroretinogram and visual-evoked potentials. Histologic changes of the retina were also examined.

RESULTS

Injection of SNAP reduced the a-wave amplitude. In contrast, the amplitudes of the oscillatory potentials were increased during the 3-hour observation period. Histologic examination showed vacuolar degeneration and loss of the nuclei of the photoreceptors. In the inner retina, some ganglion cells were lost, and cell density in the internal nuclear layer was decreased.

CONCLUSION

Retinal toxicity of NO was demonstrated functionally and histologically, suggesting that NO may play a pathophysiologic role in retinal ischemia or in degenerative retinal diseases.

Gene amplification of int-2 and erbB in human esophageal cancer: relationship to clinicopathological variables

Gene amplification is a relatively frequent event in human malignant tumors and is believed to play an important role in tumor progression. The int-2 and erbB genes are amplified more frequently than any other genes in human esophageal cancer. In order to investigate the correlation between these two proto-oncogenes and the clinical behavior of esophageal cancer, we examined DNA amplification of int-2 and erbB and analyzed their relationship to clinicopathological variables. Genomic DNA was extracted from 21 esophageal squamous carcinomas and normal esophageal mucosa, as well as from 4 metastatic tumors. We used Southern blot analysis for detection of gene amplification. Amplification of int-2 was observed in 13 of 21 cases (62%) and in all the metastatic tumors (4/4; 100%). We found a significant correlation between amplification of int-2 and the length of the primary lesion. Amplification of erbB was detected in 3 of 18 patients (17%). All patients who showed amplification of erbB also demonstrated amplification of int-2. These results suggest that amplification of int-2 or neighboring genes on 11q may participate in tumor progression and metastasis in patients with esophageal squamous cancer.

Low-level release of Shiga-like toxin (verocytotoxin) and endotoxin from enterohemorrhagic Escherichia coli treated with imipenem

Shiga-like toxin (SLT) and endotoxin may participate in the pathogenesis of enterohemorrhagic Escherichia coli (EHEC) infection. Levels of release of SLT and endotoxin from EHEC treated in vitro with antibiotics were estimated. There were differential levels of release of SLT and endotoxin from EHEC treated with different antibiotics. Treatment of EHEC strains, namely, E. coli O157, O111, and O26, with imipenem induced much lower levels of release of SLT and endotoxin than treatment with ceftazidime.

Effect of ecabet sodium on Helicobacter pylori adhesion to gastric epithelial cells

Helicobacter pylori is a major etiological agent in gastroduodenal disorders, with the adhesion of H. pylori to gastric epithelial cells being the initial step of H. pylori infection. Inhibition of H. pylori adhesion is thus a therapeutic target in preventing H. pylori infection. We evaluated the effect of ecabet sodium, an antiulcer agent, on H. pylori adhesion to gastric epithelial cells, using our previously established enzyme-linked immunosorbent assay. The adhesion of H. pylori was significantly inhibited by ecabet sodium in a dose-dependent manner. Our studies suggest that ecabet sodium inhibits the adhesion of H. pylori to gastric epithelial cells.

[Promising new drugs for gynecological cancer]

Five promising new drugs for gynecological cancer were reviewed. Taxans (Paclitaxel: Taxol and Docetaxel: Taxotere) diterpenoid plant products enhance the polymerization of tublin. Taxol showed significant activity for platinum refractory ovarian cancer in a phase 1 clinical trial in the United States. The combination with cisplatin (CDDP) showed superior results to CDDP plus Cyclophosphamide and has been recognized as a new standard in adjuvant chemotherapy for advanced ovarian cancer. The major toxicities are myelosuppression, alopecia, and hypersensitivity reactions (HSRs). HSRs were overcome by pretreatment with anti-histamines and over 24 hours administration. It was also reported that Taxol was administered safely by over 3 hours infusion with reduced myelotoxicity, but the incidence of HSRs may be increased. Clinical trials of intraperitoneal administration and combination with Carboplatin (CBDCA) are ongoing. Taxotere, an analog of Taxol, is also effective as Taxol with a low incidence of HSRs. Topoisomerase inhibitors (Irinotecan hydrochloride: CPT-11 and Topotecan) have promising antitumor activity for ovarian and cervical cancer. CPT-11 is a semisynthetic camptothesin analog developed in Japan. It was also effective for platinum-resistant ovarian cancer, such as mucinous and clear cell carcinoma. An adverse effect was observed in the combination of CPT-11 and CDDP. The phase 1 clinical trial showed a 40% response rate against recurrent ovarian cancer. CPT-11 50-60 mg/m2 (day 1,8,15) and CDDP 50-60 mg/m2 (day 1) are a recommended schedule. The major toxicities are neutropenia and diarrhea. Thrombocytopenia is not severe and diarrhea is also controllable. Topotecan is also a promising topoisomerase inhibitor and reported superior result to Taxol for platinum refractory ovarian cancer. A phase II trial is ongoing for ovarian and cervical cancer in Japan. Nedaplatin, a new analog of cisplatin, has similar activity especially for cervical cancer with less myelotoxicity and nephrotoxicity.

Helicobacter pylori extracts exhibit nicotinamide adenine dinucleotide-derived adenylation but not mono(adenosine 5'-diphosphate-ribosyl)ation of DNA ligase

The issue of toxins produced by Helicobacter pylori (H. pylori) urgently requires clarification given that the bacterium causes gastric epithelial cell damage which may lead to precancerous and cancerous changes. During an investigation of the possibility of mono(adenosine 5'-diphosphate (ADP)-ribosyl)ation by H. pylori products, as observed for other bacterial toxins, we found that radioactivity of [adenylate-32P]nicotinamide adenine dinucleotide (NAD) is incorporated into an H. pylori protein of 80 kDa after incubation with crude bacterial extract. In contrast, [carbonyl-14C]NAD did not show any radioactivity incorporation. Unexpectedly, treatment of the modified protein with 0.1 N HCl, but not 0.1 N NaOH, released the AMP moiety. Such chemical properties are characteristic of bacterial DNA ligase-AMP complexes. We found that an antibody raised against Escherichia coli DNA ligase [EC 6.5.1.2] immunoprecipitated the modified 80 kDa protein. Our results indicate that incorporation of radioactivity derived from NAD into the 80 kDa protein was due to adenylation, but not mono(ADP-ribosyl)ation, of the DNA ligase of H. pylori.

Evolutionary relationship among rfb gene clusters synthesizing mannose homopolymer as O-specific polysaccharides in Escherichia coli and Klebsiella

In order to clarify the evolutionary relationship among rfb gene clusters synthesizing mannose homopolymer as O-specific polysaccharides in Escherichia coli and Klebsiella, we studied the DNA sequence of the boundary region between the rfb and his genes in a series of strains possessing mannose homopolymer as O-specific polysaccharide. All had a characteristic gene organization carrying no gene between the rfb and his genes. Further, the recombination event was suggested to occur at the same site of the hisI gene in those strains. It was suggested that there was a close evolutionary relationship among rfb gene clusters synthesizing mannose homopolymer as O-specific polysaccharide in E. coli and Klebsiella.

Cloning of maize ferredoxin III gene: presence of a unique repetitive nucleotide sequence within an intron found in the 5'-untranslated region

A genomic clone encoding the precursor of a non-photosynthetic ferredoxin (Fd III) from maize has been isolated and characterized. In comparison with the corresponding cDNA, the gene (fedIII) was found to be interrupted in the 5'-untranslated region by an intron consisting of 3,037 bp. About 80% of the total region of this intron is organized into four classes of tandemly repeated sequences with monomeric lengths of about 200 bp, 320 bp, 130 bp, and 90 bp. This unique intron organization is present in the fedIII gene of three related maize cultivars examined.

Two forms of Wilson disease protein produced by alternative splicing are localized in distinct cellular compartments

Copper is an essential trace element in prokaryotes and eukaryotes and is strictly regulated by biological mechanisms. Menkes and Wilson diseases are human disorders that arise from disruption of the normal process of copper export from the cytosol to the extracellular environment. Recently a gene for Wilson disease (WD)(also named the ATP7B gene) was cloned. This gene encodes a copper transporter of the P-type ATPase. We prepared monoclonal and polyclonal anti-(WD protein) antibodies and characterized the full-length WD protein as well as a shorter form that is produced by alternative splicing in the human brain. We found that the WD protein is localized mainly in the Golgi apparatus, whereas the shorter form is present in the cytosol. These results suggest that the alternative WD proteins act as key regulators of copper metabolism, perhaps by performing distinct roles in the intracellular transport and export of copper.