Allelotype analysis of early colorectal cancers with lymph node metastasis

Several studies have indicated that frequent allelic losses in some specific chromosomal regions occur during colorectal cancer (CRC) progression. To clarify the correlation between such allelic losses and metastatic potential, the allelotype of lymph node-positive early CRCs, which are small but extremely malignant cancers consisting of metastatically competent cells, were investigated. Nineteen paraffin-embedded specimens of early CRC (pT1 tumors according to TNM classification) with positive lymph nodes were collected. The tumor tissues were examined for loss of heterozygosity (LOH), using microsatellite markers on chromosomes 1p34-36, 8p21-22, 14q32, 18q21 and 22q12-13. The relationship between p53 protein expression and the metastatic status was also investigated by immunohistochemical staining. A group of 20 early CRCs with negative lymph nodes having a similar distribution of macroscopic appearance were used as controls. Among the 19 node-positive tumors, LOH at 8p21-22 and 18q21 was detected in 11 cases (57.9%) and 17 cases (89.4%), respectively. Allelic losses within these 2 regions in node-positive tumors were significantly more frequent than that in node-negative ones (p < 0.01). No significant correlation was found between LOH at 1p34-36, 14q32 or 22q12-13 and lymph node metastasis. p53 protein expression was not significantly associated with lymph node metastasis. Our results suggest that putative tumor suppressor genes, which may be involved in the metastatic process of CRC, are located on chromosomes 8p21-22 and 18q21. Allelic losses in these regions are possible risk factors for lymph node metastasis of early CRC.

Requiring higher doses of erythropoietin suggests pregnancy in hemodialysis patients

BACKGROUND/AIMS

Pregnancy in hemodialysis (HD) patients tends to be diagnosed late because of its infrequency and the lack of validity of urine pregnancy tests, and because these patients tend to have menstrual irregularities. The outcome is influenced by pregnancy-related anemia. We investigated the characteristics of pregnancy-related anemia and whether it is a useful diagnostic clue to pregnancy in HD patients.

METHODS

We retrospectively investigated six pregnancies of 5 HD patients (mean age 30 years), including 4 patients treated with recombinant human erythropoietin (rHuEpo) and a transfusion-dependent patient with two pregnancies in the pre-rHuEpo era.

RESULTS

The mean duration of HD was 6 years, the mean duration of the patients' marriages at the time of pregnancy was 6 years, and the mean gestational age at diagnosis was 11 weeks and 4 days. The progression of anemia (an 8% decrease in the hematocrit) was detected by 8 weeks of gestation in all patients. The prepregnancy hematocrit was stable in 5 pregnancies, facilitating the detection of changes, but during one of the pregnancies of the transfusion-dependent patient the hematocrit was low and was influenced by the transfusions. The amount of rHuEpo required to attain a target hematocrit of 30% increased gradually or rapidly until delivery.

CONCLUSIONS

The progression of anemia or hyporesponsiveness to rHuEpo was a useful early diagnostic clue to pregnancy in HD patients. However, the prepregnancy hematocrit should be stabilized with rHuEpo, so that decreases can be easily detected. The precise mechanisms of hyporesponsiveness to rHuEpo, which progressed during pregnancy and subsided after delivery, remain to be clarified.

Amelogenin expression in canine oral tissues and lesions

Amelogenins are major enamel proteins within the enamel extracellular matrix. The expression of amelogenin was confirmed in neonatal tissues of the canine jaw. The sequence of a portion of canine amelogenin cDNA, within exons 5 and 6, was determined and found to be closely homologous to sequences reported in the cow, pig, mouse and human being. Two acanthomatous epulides collected from clinically affected dogs showed amelogenin expression, whereas 22 other canine oral lesions, including six additional acanthomatous epulides, did not show amelogenin expression. Examination of structural proteins may allow precise identification of the histogenesis of the odontogenic neoplasms, which are often difficult to distinguish by means of morphological criteria alone.

Promoter analysis of the human mismatch repair gene hMSH2

The human DNA mismatch repair gene homologue hMSH2 is involved in hereditary nonpolyposis colorectal cancer. We isolated and characterized the 5' upstream region, about 4.4kbp, of the hMSH2 gene. This region contains CpG islands and a number of elements involved in constitutive expression, but there is no TATA-box nearby the transcription start points. This is the typical structure for many promoters of housekeeping genes. Alu sequences and mononucleotide repeats are clustered in this region and there are two transcription start points. Deletion analysis revealed that less than 300bp was sufficient to initiate transcription. Although no mutation that influences promoter activity of this region was found, a polymorphism was detected by PCR-RFLP analysis. Because informative cases (C/T heterozygous) were relatively high ( approximately 30%), this polymorphism is suitable for a marker to examine allelic losses.

Functional domains of rep2, a transcriptional activator subunit for Res2-Cdc10, controlling the cell cycle "start"

In the fission yeast Schizosaccharomyces pombe, passage from G1 to S-phase requires the execution of the transcriptional factor complex that consists of the Cdc10 and Res1/2 molecules. This complex activates the MluI cell cycle box cis-element contained in genes essential for S-phase onset and progression. The rep2(+) gene, isolated as a multicopy suppressor of a temperature-sensitive cdc10 mutant, has been postulated to encode a putative transcriptional activator subunit for the Res2-Cdc10 complex. To identify the rep2(+) function and molecularly define its domain organization, we reconstituted the Res2-Cdc10 complex-dependent transcriptional activation in Saccharomyces cerevisiae. Reconstitution experiments, deletion analyses using one and two hybrid systems, and in vivo Res2 coimmunoprecipitation assays show that the Res2-Cdc10 complex itself can recognize but cannot activate MluI cell cycle box without Rep2, and that consistent with its postulated function, Rep2 contains 45-amino acid Res2 binding and 22-amino acid transcriptional activation domains in the middle and C terminus of the molecule, respectively. The functional essentiality of these domains is also demonstrated by their requirement for rescue of the cold-sensitive rep2 deletion mutant of fission yeast.

Small renal cell carcinoma: MRI with pathologic correlation

The MRI features of small renal cell carcinomas (RCCs) were retrospectively reviewed and correlated with histology in 24 patients. MRI features on both T1- and T2-weighted images were classified into hypointensity, isointensity, and hyperintensity. Each tumor was pathologically classified into four types: alveolar, papillary, tubular, and cystic. These findings were correlated with MR signal intensities. Alveolar tumors showed hypointensity to isointensity on T1-weighted image and isointensity to hyperintensity on T2-weighted image. In contrast, all papillary tumors showed hypointensity on T2-weighted image. Four of six tumors with hypointensity on T2-weighted image were caused by hemosiderin deposition, hemorrhage, and necrosis. However, there were two papillary RCCs that showed hypointensity on T2-weighted image despite no hemosiderin deposition and no hemorrhage. We conclude that papillary RCC is associated with T2-hypointense appearance as well as hemosiderin deposition, hemorrhage, and necrosis.

Genetic alterations are frequent in APC but rare in the TGF-beta type II receptor gene in cancer in adenomas of the colon

Cancer in adenomas are thought to be an excellent model of colorectal carcinogenesis based on the adenoma-carcinoma sequence. We searched for alterations in the APC mutation cluster region, the whole coding regions of TGF-beta type II receptor (RII) and beta-catenin exon 3 in 16 cases of cancer in adenomas of the colon. Overexpression of the p53 protein was also analyzed. Nine of the 16 cases showed APC mutations in both the adenoma and cancer regions. Loss of heterozygosity in APC was found in one cancer in adenoma that had no mutation. p53 overexpression was detected in one adenoma and 10 cancerous regions, most of which also exhibited APC alterations. Two cases showed a missense mutation at codon 191 or loss of heterozygosity in TGF-beta RII in both the adenoma and cancer. Our data support the hypothesis that alterations of APC and p53 are responsible for most of the adenoma-carcinoma pathway, rather than TGF-beta RII alterations.

Enhancement of phase-contrast MR angiography with superparamagnetic iron oxide

The effect of superparamagnetic iron oxide particles (AMI-227) was assessed in three-dimensional (3D) phase-contrast (PC) MR angiography (MRA), with various scanning parameters for rats at 1.5 T. The blood T1 and T2 before and after 20 micromol Fe/kg of AMI-227 injection were measured sequentially at .47 T. The visualization of abdominal aorta, renal artery, inferior vena cava, and portal vein was respectively evaluated before and after AMI-227 injection qualitatively by the four confidence levels and quantitatively by analysis of signal-to-noise ratio (SNR) of vessels. The blood T1 and T2 were sufficiently shortened for at least 1 hour after AMI-227 injection. The visualization of each vessel was improved by AMI-227 at various velocity encoding (VENC) value, suggesting the extended application of PC-MRA in various conditions. The optimal flip angle was increased from 20 degrees to 30 degrees in higher VENC after AMI-227 injection, resulting in higher signal from blood flow. Quantitative analyses showed that the optimal flip angle to achieve the maximum SNR seemed to be 20 degrees in unenhanced images, but the optimal flip angle of the high speed flow was increased by contrast enhancement. The postcontrast PC-MRA provides the increased sensitivity of slow flow components, even with a high VENC gradient. AMI-227 can significantly improve SNR to blood vessels during 3D-PC-MRA with various scanning parameters.

Isolation and characterization of the 5' region of the human mismatch repair gene hPMS1

The hPMS1 gene encodes a mutL homolog that is implicated in DNA mismatch repair and was found to be mutated in the germline of a patient with hereditary nonpolyposis colorectal cancer (HNPCC). To understand transcriptional regulation and to perform mutational analysis in the promoter region, we cloned and characterized the genomic sequence of the 5' region of the gene. hPMS1 has an intron upstream of the initiation codon. There were several transcripts with alternative splicing sites and multiple transcriptional start sites. The cloned 1.4-kbp fragment of the 5' region contains a CpG island but no TATA-boxes, typical for promoters of housekeeping genes. The promoter activity of the fragment was almost equal to that of the SV40 early promoter. Deletion analysis showed that about a 300-bp region was sufficient to initiate transcription. Although we searched for mutations in the hPMS1 promoter region in HNPCC kindreds, neither germline nor somatic mutations were detected. However, we found a highly informative polymorphism in the first exon that is useful for searching allelic losses because no polymorphic changes in hPMS1 have been reported previously.

Proapoptotic gene BAX is frequently mutated in hereditary nonpolyposis colorectal cancers but not in adenomas

BACKGROUND & AIMS

The p53 and BAX genes have been linked to apoptosis. p53 was not frequently found to be mutated in colorectal carcinomas with a microsatellite mutator phenotype, but frame-shift mutations in a tract of eight guanines within BAX were frequently found in these carcinomas. To understand the roles of these genes in hereditary nonpolyposis colorectal cancer (HNPCC) tumorigenesis, we examined whether BAX mutations occur in adenoma and carcinoma specimens from patients with HNPCC and also determined the frequencies of p53 mutations.

METHODS

Thirteen colorectal adenomas and 24 adenocarcinomas from patients with HNPCC showing a microsatellite instability phenotype were screened by polymerase chain reaction followed by denaturing polyacrylamide gel electrophoresis and direct sequencing.

RESULTS

Two of the 13 adenomas (15.4%) and 13 of the 24 adenocarcinomas (54.2%) showed mutation patterns and were confirmed to have frame-shift mutations at the BAX repeat site by direct sequencing. For p53, only 1 of the 24 adenocarcinomas (4.2%) showed a missense mutation.

CONCLUSIONS

In HNPCC colorectal carcinomas, BAX was significantly (P = 0.024) more mutated than in adenomas. p53 was not frequently found to be mutated in these carcinomas. These data suggest that mutations in BAX, rather than mutations in p53, may contribute to the adenoma-carcinoma transition in HNPCC tumorigenesis.

Genomic structure of the human Smad3 gene and its infrequent alterations in colorectal cancers

The Smad3 gene is a member of the Smad family, vertebrate homologues of Drosophila Mad, and its gene product is a cytoplasmic element in the TGF-beta signaling pathway. Smad2 and Smad4/DPC4, other members of the Smad family, are possibly tumor suppressor genes because alterations of these genes occurred in various carcinomas. We determined the genomic structure of human Smad3 which consists of nine exons. Then we examined whether or not Smad3 gene mutations exist in sporadic and hereditary non-polyposis colorectal cancers and found no mutations in the entire coding region in 50 cancers. Loss of heterozygosity of Smad3 was observed in two of the 17 (11.8%) informative cases using a polymorphism found in intron 2. These findings suggest that the Smad3 gene may not play an important role in the tumorigenesis of colorectal cancers.

Dynamic MR Imaging and Tumor Angiogenesis in DMBA-Induced Rat Breast Cancer: Three Dimensional (3D) Reconstructed Image Analysis of Tumor Microvessels by Confocal Laser Scanning Microscopy

We investigated the correlation between dynamic magnetic resonance imaging (MRI) findings in breast cancer and tumor angiogenesis in a dimethylbenz(a)anthracene(DMBA)-induced rat breast cancer model. In this study, we clearly demonstrated the three-dimensional (3D) architecture of tumor microvessel networks(MN)by confocal laser scanning microscopy (CLSM)and also investigated the hyperpermeability of tumor microvessels. Dynamic MRI findings were closely related to tumor angiogenesis. Three-dimensional reconstructed image analysis by CLSM revealed that the depicted images were dependent on microvessel density as well as microvessel permeability. It should be emphasized that dynamic MRI may have the potential to evaluate the tumor angiogenic activity in human breast carcinoma.

Genetic polymorphisms of tobacco- and alcohol-related metabolizing enzymes and human esophageal squamous cell carcinoma susceptibility

Many human cancers are caused by synthetic or natural chemical compounds in the environment. Esophageal squamous cell carcinoma has been reported to be epidemiologically associated with tobacco and alcohol consumption. We studied the association between genetic polymorphisms of tobacco- and alcohol-related metabolizing enzymes and esophageal squamous cell carcinoma susceptibility. We examined genetic polymorphisms of the CYPIA1, GSTM1, CYPIIE1, ADH2, and ALDH2 genes in 94 Japanese patients with esophageal squamous cell carcinoma and 70 unrelated healthy Japanese persons. There were no significant differences between healthy controls and patients with esophageal cancer in the polymorphisms of the CYPIA1, GSTM1, and CYPIIE1 genes. On the other hand, there were significant differences in the ADH2 and ALDH2 polymorphisms between healthy controls and esophageal cancer patients. The ADH2(1)/ADH2(1) and ALDH2(1)/ALDH2(2) genotypes were independently and significantly higher in esophageal cancer patients than in healthy controls. Furthermore, persons with the combined genotypes ADH2(1)/ADH2(1) and ALDH2(1)/ALDH2(2) were at extraordinarily high risk for esophageal squamous cell carcinoma, with an odds ratio of 17.9 (p < 0.001). Thus polymorphisms of alcohol-metabolizing enzymes, that is, ADH2 and ALDH2, may be useful for screening patients at high risk for esophageal cancer, which might facilitate clarification of esophageal tumorigenesis and prevention of esophageal cancer.

[Experimental study on intraperitoneal sequential MTX/5-FU therapy for peritoneal seeding in comparison with intravenous administration]

Sequential MTX/5-FU therapy (intravenous route) is powerful chemotherapy especially for poorly differentiated adenocarcinoma of the stomach and its peritoneal metastases. The authors had proposed the idea of intraperitoneal sequential MTX/5-FU chemotherapy for potential peritoneal metastases and micrometastases from advanced gastric carcinoma. This experimental study was planned to confirm this experimentally. Peritoneal seeding model of nude mice was made by the intraperitoneal inoculation of human gastric cancer cell line MKN-45. Control group (n = 5) had no treatment. The intraperitoneal (i.p.) group and intravenous (i.v.) group underwent the treatments on the 7th, 14th, and 21st day after cell implantation. Experimental chemotherapies consisted of intraperitoneal injection of MTX (15 mg/kg, 1.5 ml saline) and 5-FU (50 mg/kg, 1.0 ml saline) for i.p. group and intravenous injection of MTX (15 mg/kg, 0.2 ml saline) and 5-FU (50 mg/kg, 0.2 ml saline) for i.v. group. Interval time between MTX and 5-FU administration was 2 hours. On the 35th day after the cell implantation necropsies were performed. Counting of peritoneal metastatic nodules revealed the number of nodules of control group. (14.2 +/- 6.7) > i.v. group (5.3 +/- 4.1) > i.p. group (0.41 +/- 0.7) (p < 0.05). Weight of omental tumors showed Control group (0.246 +/- 0.136 g) > i.v. group (0.140 +/- 0.068 g) > i.p. group (0.051 +/- 0.017 g) (i.v.-i.p., p < 0.01). The mouse body weight decrease less in the i.p. group than in the i.v. group (p < 0.05) throughout this experiment. The results of this experiment demonstrated intraperitoneal sequential MTX/5-FU therapy was more effective than intravenous sequential MTX/5-FU therapy for potential peritoneal seeding and peritoneal micrometastases from the gastric cancer. Moreover, the side effect of intraperitoneal administration was milder than by the intravenous route.

[Synthesis of promin in Japan and global elimination of Hansen's disease]

Prof. Morizo Ishidate synthesized "Promin" for the treatment of leprosy/Hansen's disease which had been considered "incurable" until the discovery of antileprosy effect of that drug by Dr. Faget of U.S.A. in 1941. Prof. Ishidate was the first to synthesize the drug in Japan in 1946 based on a brief news item on a Swiss journal smuggled in during the War. For this achievement, he is known as "father of chemotherapy for leprosy in Japan." Prof. Ishidate also contributed to the global fight against leprosy as the Chairman of the Board of Directors of Sasakawa Memorial Health Foundation, which he helped to establish in May 1974, with a full financial backing of Mr. Ryoichi Sasakawa, President of Japan Shipbuilding Industry Foundation. Prof. Ishidate, with his scientific knowledge as well as christianity based humanitarian concern, advised Mr. Sasakawa how to spend JSIF money wisely for eliminating leprosy and nearly US$200 million was channeled through WHO and SMHF. The successful outcome of global multidrug therapy (MDT) programme in the '80s resulted in the adoptation of resolution by the World Health Assembly, "Elimination of Leprosy, as a public health problem" by the Year 2000. The synthesis of "Promin" in Japan and promoting the global implementation of MDT, both achievement can be attributed to Prof. Ishidate.

Switch from conventional to high-flux membrane reduces the risk of carpal tunnel syndrome and mortality of hemodialysis patients

The use of a high-flux membrane, which eliminates larger molecular weight solutes with better biocompatibility, has steadily increased since the discovery of beta-2 microglobulin (beta 2m) amyloidosis in 1985. The long-term effects of a dialyzer membrane on morbidity and mortality are not completely understood. To examine the membrane effect as a factor of carpal tunnel syndrome onset and mortality, multivariate Cox regression analysis with time-dependent covariate was conducted on 819 patients from March 1968 to November 1994 at a single center. Two hundred and forty-eight of the patients were either switched from the conventional to high-flux membrane or treated only with a high-flux membrane. Fifty-one patients underwent a CTS operation and 206 died. Membrane status (on high-flux or on conventional) was considered as time-dependent covariate and risk was adjusted for age, gender, type of renal disease and calendar year of dialysis initiation. The relative risk of CTS was reduced to 0.503 (P < 0.05) and mortality 0.613 (P < 0.05) by dialysis on the high-flux membrane, compared to the conventional membrane. Serial measurements of beta 2m indicated significantly lower beta 2m to persist in patients on the high-flux membrane. The high-flux membrane decreased the risk of morbidity and mortality substantially. Larger molecule elimination was shown important not only for preventing beta 2m amyloidosis, but for prolonging survival of dialysis patients as well.

Germ-line mutation of the hMSH6/GTBP gene in an atypical hereditary nonpolyposis colorectal cancer kindred

A germ-line mutation of hMSH6 (also called GTBP) was found in a hereditary nonpolyposis colorectal cancer (HNPCC)-like patient in whom germ-line mutations of hMSH2, hMSH3, or hMLH1 had not been detected. The patient had rectal cancer and two colon adenomas at 62 years of age and a weak family history of gastrointestinal tumors, indicating atypical HNPCC. Somatic mutations of hMSH6 were observed in three colorectal tumors from the patient, indicating two-hit inactivation. Microsatellite instabilities at mononucleotide repeats were detected in all three tumors. These data suggest that hMSH6 is responsible for tumorigenesis in atypical HNPCC.

Efficacy of interferons in treating children with chronic hepatitis C

Twenty-two children with chronic hepatitis serologically positive for hepatitis C virus (HCV) were treated with interferon-alpha (IFN-alpha). Liver biopsy showed chronic active hepatitis in 13 and chronic persistent hepatitis in 9 patients. A sustained clearance of HCV was observed in 8/22 children 12 months after the administration of IFN-alpha for 26 weeks, associated with normalization of HCV core antibody. Of these eight patients six had HCV genotype III and two HCV genotype II or IV. Hepatitis relapsed in seven other patients after completion of IFN-alpha with an increase in HCV core antibody titre, five with HCV genotype II, and two with HCV genotype III or IV. A second course of IFN-alpha suppressed the reactivation of HCV in all seven patients. Three of seven responders who relapsed after the first course remained negative for HCV RNA 12 months after their second course of IFN-alpha. However, the remaining four patients with HCV genotype II again relapsed after completing their second course of IFN-alpha. Seven children with the HCV genotype II resistant to IFN, including 8 weeks of IFN-beta administration, and showed no significant reduction in HCV core antibody titre.

CONCLUSION

The genotype of HCV (III) and a reduction in the core antibody titre appear to be useful parameters for predicting the response to IFN-alpha therapy.

[Comparison between intraperitoneal and intravenous 5-fluorouracil administration using pancreatic cancer model of nude mouse]

Carcinoma of the pancreas is a virulent malignancy. The purpose of this study was to evaluate the efficiency of 5-FU intraperitoneal administration for this malignancy. We developed a pancreatic cancer model whereby a human pancreatic cell line, MIA PaCa-2, was orthotopically transplanted to the pancreas of nude mice as cell suspension (1 x 10(6) cells). IP group (n = 6) received 5 times IP administration (4, 7, 12, 16, 20 days after implantation) of 5-FU 50 mg/kg, 1.5 ml. IV group (n = 6) received 5 times IV therapy (the same dates as IP group) of 5-FU 50 mg/kg, 0.2 ml. Control group (n = 6) received no treatment. The mice were sacrificed 42 days after implantation. The weight of the tumors of IP, IV and Control group was 0.332 +/- 0.143 g, 0.138 +/- 0.047 g and 0.329 +/- 0.085 g. Significant differences were found between IP and IV, and control. There was no difference between IP and control. This experiment demonstrated that 5 FUIP therapy for primary pancreatic cancer showed no effect and 5 FUIV therapy was much more effective.

[TGF-beta and its receptors]

TGF-beta is a member of a superfamily associated with development and regulation of cell growth. Recently, its two receptors and intracellular components of signal transduction, a Smad family, have been identified. The type II receptor gene has been found to be mutated specifically in hereditary colon cancers, HNPCC. Alterations of the Smad 4 gene were also detected in pancreatic and colorectal cancers.

Analyses of the APC and TGF-beta type II receptor genes, and microsatellite instability in mucosal colorectal carcinomas

APC and transforming growth factor-beta type II receptor (TGF-beta RII) gene mutations, and microsatellite instability have been found in sporadic colorectal carcinomas. To clarify further the early alterations in colorectal carcinogenesis, we investigated these genetic changes in 23 protruding- and 24 superficial-type mucosal colorectal carcinomas. TGF-beta RII gene mutations and microsatellite instability were rarely found in these lesions. Nevertheless, APC was mutated in 16 of the 47 (34.0%) mucosal colorectal carcinomas and was significantly more frequently mutated in protruding- (I) and superficial elevated-type (IIa) (14/32, 43.8%) than in other superficial-type (IIa+IIc, IIb, IIc, and IIc+IIa) (2/ 15, 13.3%) mucosal colorectal carcinomas (P < 0.04). These results indicate that the APC gene may be involved from the beginning in the tumorigenesis of many early colorectal carcinomas, particularly of the protruding and superficial elevated types. However, there might be a distinct pathway for other superficial-type colorectal carcinomas, possibly not involving APC as an initial step of tumorigenesis.

Frequent somatic mutations of hMSH3 with reference to microsatellite instability in hereditary nonpolyposis colorectal cancers

hMSH3 is one of the human DNA mismatch repair genes but has not yet been reported to be associated with hereditary nonpolyposis colorectal cancer. Recently, somatic mutation at a polyadenine tract, i.e., (A)8, in hMSH3 was reported in cancers with microsatellite instability (MI). To clarify the tumorigenetic role of hMSH3, we screened for somatic mutations at the hMSH3 (A)8 repeat in 29 tumors from 23 hereditary nonpolyposis colorectal cancer patients. One or two A deletions in the (A)8 repeat were found in 11 (57.9%) of the 19 MI-positive tumors but not in 10 MI-negative ones, indicating secondary mutations after germline mutations of other mismatch repair genes. Moreover, the MI frequency of three or more nucleotide repeats was higher in hMSH3 (A)8-mutated tumor cells than in nonmutated ones (p<0.05). These data suggest that a mutation of a mismatch repair gene enhances the frequency of another mismatch repair gene mutation, such as of hMSH3, resulting in severe MI.

Effect of friction coefficient on Akers clasp retention

STATEMENT OF PROBLEM

Retentive force control of clasp retainers is one of the most essential factors for the successful function of removable partial dentures. However, it is not yet known how the friction coefficients differ among restored abutments and clasp materials, and how the friction coefficients affect the retention of clasps.

PURPOSE

The purposes of this study were to clarify the friction coefficients among restored abutments and clasp materials and to estimate the effect of friction coefficients on the retention of clasps.

MATERIAL AND METHODS

The coefficients of static friction between three clasp materials (type IV gold, high Pd, and cobalt-chromium [Co-Cr] alloys) of two surface treatments (polished and sandblasted) and four abutment materials (human enamel, porcelain, type IV gold, and high Pd alloys) were evaluated under three conditions (dry, wet with water, and wet with saliva), and theoretically, the effect of the friction coefficients on clasp retention was estimated.

RESULTS

The friction coefficients under various conditions ranged from 0.08 (polished Co-Cr clasp on type IV abutment in dry condition) to 0.37 (sandblasted Co-Cr clasp on high Pd abutment in dry condition). The theoretical estimation clarified that the retentive force of the clasp was linear to the friction coefficient.

CONCLUSION

The retentive force increased linearly with increasing friction coefficient between abutment material and clasp material according to the newly developed formula. This study suggested that clasp designs should be changed depending on abutment materials.

Analysis of a polyadenine tract of the transforming growth factor-beta type II receptor gene in colorectal cancers by non-gel-sieving capillary electrophoresis

We developed a method to analyze a polyadenine tract, the (A)10 repeat, within the cysteine-rich domain of the transforming growth factor-beta (TGF-beta) type II receptor gene using a non-gel-sieving capillary electrophoresis technique and applied it to the DNA diagnosis of colorectal cancers. This method consists of single-strand DNA amplification of the (A)10 repeat by an asymmetric PCR technique and capillary electrophoresis. A higher concentration of dATP in the PCR reaction mixture led to more specific amplification of the (A)10 repeat. Under the optimal electrophoretic conditions, one nucleotide difference could be determined in 8 to 32 nucleotides. One or two base deletions of the (A)10 repeat in colorectal cancers could be detected under these conditions within 30 min, and the results coincided with those obtained on DNA sequencing analyses. According to a sensitivity study, we could detect the deleted sequence if it was present in 12.5% or more of the wild-type allele. The reproducibility of this technique was satisfactory because the intraassay imprecision (CV) (n = 10) was 1.4%. These results indicate that capillary electrophoretic analysis of small repeated sequences results in easier handling and more feasible automation, compared with conventional gel electrophoretic analysis.

Proto-oncogene of int-3, a mouse Notch homologue, is expressed in endothelial cells during early embryogenesis

BACKGROUND

Notch and its homologues are key regulatory receptors of the cell fate decision in various developmental processes. The int-3 oncogene was originally identified as a frequent target in Mouse Mammary Tumour Virus (MMTV)-induced mammary tumours and has been regarded as a Notch homologue, based on its similarity to the intracellular domain of Notch. Studies with int-3 transgenic mice have suggested that the int-3 transgene affects the differentiation capacity of stem cells and leads to neoplastic proliferation in epithelial cells. However, the exact nature and the in vivo expression pattern of the int-3 proto-oncogene are unknown. The function of gene products in embryogenesis is also not clear.

RESULTS

We isolated cDNA clones corresponding to the proto-oncogene of int-3 and analysed its overall structure. The predicted amino acid sequence of the int-3 proto-oncogene contains the conserved motif found in Notch family receptors. Therefore, we name Notch-4 for the int-3 proto-oncogene. However, Notch-4 has fewer EGF repeats and shows less similarity to Notch, compared with other mammalian Notch homologues. In embryogenesis, the expression of Notch-4 was detected in endothelial cells of blood vessels forming tissues such as the dorsal aorta, intersegmental vessels, yolk sac vessels, cephalic vessels, heart, vessels in branchial arches, and capillary plexuses. In these tissues, Notch-4 expression coincided with flk-1, the major regulatory gene of vasculogenesis and angiogenesis. We also found that Notch-4 expression was up-regulated in vitro during the differentiation of endothelial cells from embryonic stem cells (ES cells).

CONCLUSION

The endothelial cell specific expression pattern of Notch-4, as well as its structural similarity of Notch, suggest that Notch-4 is an endothelial cell specific homologue of Notch and it may play a crucial role in vasculogenesis and angiogenesis.

Transforming growth factor beta type II receptor gene mutations in adenomas from hereditary nonpolyposis colorectal cancer

BACKGROUND & AIMS

Germline mutations of DNA mismatch repair genes are responsible for cancer susceptibility in hereditary nonpolyposis colorectal cancer (HNPCC) kindreds. Transforming growth factor beta type II receptor (TGF-beta RII) has been found to be somatically altered in HNPCC. The aim of this study was to clarify further the role of TGF-beta RII alterations in HNPCC tumorigenesis, particularly in adenomas.

METHODS

Fourteen adenoma specimens and 13 cancer specimens from 10 patients with HNPCC were screened for mutations in the short repeated sequences of the TGF-beta RII gene by polymerase chain reaction-single-strand conformation polymorphism. Mismatch repair genes, replication errors, and c-K-ras 2 were also analyzed in HNPCC tumors.

RESULTS

Alterations of the TGF-beta RII gene at the short poly(A) repeat were found in 8 (57%) adenoma specimens and 11 (85%) cancer specimens. They were found at an earlier stage of adenomas. Two adenoma specimens showed two-hit inactivation of mismatch repair genes. Replication errors were detectable in 13 (93%) adenoma specimens. Mutations in c-K-ras 2 codon 12 were detected at a 50% frequency in adenoma specimens.

CONCLUSIONS

These data indicate a strong association between TGF-beta RII gene alterations and adenoma-carcinoma progression in HNPCC.

Performance of Gd-EOB-DTPA and superparamagnetic iron oxide particles in the detection of primary liver cancer: a comparative study by alternative free-response receiver operating characteristic analysis

The performance of gadolinium-ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) and superparamagnetic iron oxide (SPIO) particles in detecting liver cancer was compared using alternative free-response receiver operating characteristic (AFROC) analysis, which allowed observers to indicate both the confidence level and the locations of all perceived abnormalities. Axial T1-weighted MR images (1.5 T) pre/post Gd-EOB-DTPA (25 mumol/kg) injection were obtained for 12 rats with chemically induced liver tumors (64 tumors). T2-weighted images (T2WI) were obtained pre/post SPIO (10 mumol/kg) injection for the same animal. Liver signal-to-noise ratio (SNR), tumor-liver contrast-to-noise ratio (CNR), and histopathologic sections corresponding to MR images were obtained. In AFROC, the location and the confidence level for each tumor were indicated independently on MR images by four radiologists. By plotting true-positive fraction and probability of false-positive per image, the area under the AFROC curve (A1) was estimated and statistically analyzed between each sequence. Either drug significantly improved tumor-liver CNR (P < .001) and tumor detection (diameter < or = 6 mm; P < .05). Gd-EOB-DTPA significantly (P < .05) improved the A1 in T1WI. There was no A1 difference between T2WI + SPIO and T1WI + Gd-EOB-DTPA. Gd-EOB-DTPA-enhanced T1WI showed the same performance as SPIO-enhanced T2WI in detecting liver tumors.

Mutations of the transforming growth factor-beta type II receptor gene are strongly related to sporadic proximal colon carcinomas with microsatellite instability

BACKGROUND

Mutations of the transforming growth factor-beta type II receptor gene (TGF-beta RII) have been found in several replication error-positive sporadic colorectal carcinomas and hereditary nonpolyposis colorectal carcinoma cell lines. The aim of this study was to clarify the role of TGF-beta RII in sporadic colorectal carcinogenesis.

METHODS

The authors screened for mutations at simple repeated sequences in the TGF-beta RII gene by polymerase chain reaction-single strand conformation polymorphism. They also examined genomic instability, using five microsatellite DNA markers in 69 sporadic colorectal carcinomas. When the carcinomas exhibited the TGF-beta RII mutations, the authors screened further for mutations in two DNA mismatch repair genes, hMSH2 and hMLH1.

RESULTS

Seven of the 69 cancers (10%) showed one or two A deletions in TGF-beta RII and resultant frameshift mutations in nucleotide positions 709-718 containing a (A) 10 repeated sequence; but none of these appeared in the corresponding normal DNA, indicating a somatic mutation. All of the seven cancers were located in the proximal colon; there were none in the distal colon (P < 0.01). On the other hand, 22 of the 69 carcinomas (32%) showed the replication error-positive phenotype. The frequency of replication errors in proximal colon carcinomas was higher than that in distal colon carcinomas (P < 0.05). All 7 cancers with TGF-beta RII mutations showed replication errors. One of them revealed a nonsense mutation at codon 413, and 1 revealed a loss of heterozygosity in hMSH2.

CONCLUSIONS

These data indicate that mutations of TGF-beta RII are strongly related to proximal colon carcinomas with microsatellite instability and that the mechanism of carcinogenesis in some proximal colon carcinomas is similar to that in hereditary nonpolyposis colorectal carcinoma.

Genomic structure of the transforming growth factor beta type II receptor gene and its mutations in hereditary nonpolyposis colorectal cancers

To characterize the tumorigenetic role of the transforming growth factor beta type II receptor (RII) gene, we defined its genomic structure, which consists of seven exons. The sequences of exon-intron junctions were determined to facilitate mutation analysis of each exon. Twenty-five carcinomas and five adenomas from hereditary nonpolyposis colorectal cancer patients were analyzed for mutations in the entire coding region. Four missense mutations (two in adenomas and two in carcinomas) were found in the 10 cases carrying the polyadenine deletions in one allele. These results indicate that RII shares the two-hit inactivation mechanism with tumor suppressor genes and that mutations of it may occur in the early stage of tumorigenesis.

Clonal heterogeneity in human esophageal squamous cell carcinomas on DNA analysis

Cancers are thought to arise through multistep accumulation of somatic mutations in the progeny of a single cell. Multiple mutations may induce molecular intratumor heterogeneity. Therefore, we examined molecular clonal heterogeneity in esophageal squamous cell carcinomas. Twenty-four esophageal squamous cell carcinomas and associated lymph node metastases were examined for microsatellite alterations, and abnormalities of the p53 and transforming growth factor-beta type II receptor (TGF-beta RII) genes. There were eight cases (33%) showing different patterns of loss of heterozygosity in primary tumors and metastatic lymph nodes with microsatellite markers. On the other hand, the abnormalities of p53 were identical in all these cases. No mutation was detected in the simple repeated sequences of the TGF-beta RII gene. These results indicate that molecular clonal heterogeneity exists in esophageal squamous cell carcinomas. Therefore, care is necessary in preoperative genetic diagnosis using biopsy samples.

Frequent microsatellite instabilities and analyses of the related genes in familial gastric cancers

Microsatellite instability or replication error seems to be related to defective DNA mismatch repair genes, such as hMSH2, hMLH1, hPMS1 and hPMS2, which have been identified as causative genes of hereditary nonpolyposis colorectal cancers (HNPCC). Recently, it was reported that mutations at the simple repeated sequences in the transforming growth factor-beta type II receptor (TGF-beta RII) gene occurred in replication error-positive colorectal cancers. To determine genetic alterations in familial gastric cancers (FGC, we examined replication error using eight microsatellite DNA markers, and screened mutations in the hMSH2, hMLH1 and TGF-beta RII genes in six cases from four FGC kindreds. Moreover, hMTH1, a human homolog of the bacterial mutT gene, was also screened. Four of six (67%) cancers showed the replication error-positive phenotype, indicating that microsatellite instability is highly associated with not only HNPCC, but also FGC. No germline mutation was found in the whole coding sequences of hMSH2 and hMTH1, or in the conservative regions of hMLH1 in any patient, while one cancer DNA showed a somatic mutation at codon 682 (threonine to alanine) in hMSH2. No alteration was found at the small repeated sequences in TGF-beta RII in FGC tumor DNA. These results indicate that the carcinogenetic process of FGC may be different from that of HNPCC.

[Human mismatch repair genes and HNPCC]

Hereditary nonpolyposis colorectal cancer (HNPCC) is a major cancer susceptibility syndrome known to be caused by the inheritance of mutations in DNA mismatch repair genes, such as hMSH2, hMLH1, hPMS1 and hPMS2. Germline mutations in the hMSH2 and hMLH1 genes were detected in 9 and 11 Japanese or Korean HNPCC kindreds, respectively. These data establish a basis for the presymptomatic diagnosis of HNPCC patients. To determine the relation between the mutation of the TGF-beta type II receptor gene and genomic instability in the tumorigenesis of HNPCC, we screened genomic DNA of tumors from HNPCC patients. Seventeen of the 24 (71%) genomic instability-positive HNPCC tumors carried one or two A deletions in the (A)10 repeat, while none of the 14 genomic instability-negative tumors did. These deletions inactivate the receptor through a frameshift mutation and the resultant protein truncation. These data suggest that the TGF-beta type II receptor gene is a major target of genomic instability in HNPCC tumorigenesis.

[Analyses of mutator gene mutations in familial gastric cancers]

The clinical and genetic studies have been very few on a familial predisposition to gastric cancers. We defined the criteria as familial gastric cancer (FGC) in which at least three relatives in two generations have gastric cancers, with one of the relatives having been diagnosed at less than 50 years of age. Other hereditary tumors, such as cancer family syndrome of hereditary nonpolyposis colorectal cancer(HNPCC), should be excluded. To clarify the carcinogenesis in FGC, we examined genetic alterations in six cancers from four FGC kindreds. Four (67%) cancers showed replication error, indicating that microsatellite instability is highly associated with not only HNPCC but also FGC. However, no germline mutation was found in the whole coding sequences of hMSH2 and hMTH1, or in the conservative regions of hMLH1 in any patients. Only few alterations were found at the small repeated sequences in the transforming growth factor-beta type II receptor gene in FGC tumor DNA. These results indicate that the carcinogenetic process of FGC may be different from that of HNPCC.

Retrospective survey of chronic Q fever in Japan by using PCR to detect Coxiella burnetii DNA in paraffin-embedded clinical samples

We used PCR to detect Coxiella burnetii DNA in paraffin-embedded tissues obtained from patients with chronic endocarditis in which the etiological agent had been unknown. On the basis of the published nucleotide sequence of the C. burnetii htpB gene, primers were chosen to produce an amplified fragment of 285 bp. A total of 60 samples from 56 patients were tested for the presence of C. burnetii DNA. Five samples from four patients were found to be positive. All of the amplified DNA fragments possessed a TthHB8I restriction site, as predicted from the published sequence of C. burnetii. In one of the four positive patients, rickettsia-like particles were found in sections of tissue stained by Gimenez's method. This is the first report of chronic Q fever in Japan.

Loss or somatic mutations of hMSH2 occur in hereditary nonpolyposis colorectal cancers with hMSH2 germline mutations

Hereditary nonpolyposis colorectal cancer (HNPCC) is a major cancer susceptibility syndrome known to be caused by the inheritance of mutations in DNA mismatch repair genes, such as hMSH2, hMLH1, hPMS1 and hPMS2. To investigate the role of genetic alterations of hMSH2 in HNPCC tumorigenesis, we analyzed 36 Japanese HNPCC kindreds as to hMSH2 germline mutations. Moreover, we also examined somatic mutations of hMSH2 or loss of heterozygosity at or near the hMSH2 locus in the tumors from the hMSH2-related kindreds. Germline mutations were detected in five HNPCC kindreds (5/36, 14%). Among them, three were nonsense mutations, one was a frameshift mutation and the other was a mutation in an intron where the mutation affected splicing. Loss of heterozygosity in four and somatic mutations in one were detected among the eight tumors with hMSH2 germline mutations. All these alterations were only detected in genomic instability(+) tumors, i.e., not in genomic instability(-) ones, indicating that mutations of hMSH2 were responsible for at least some of the tumors with genomic instability. These data establish a basis for the presymptomatic diagnosis of HNPCC patients, and constitute further evidence that both DNA mismatch repair genes and tumor suppressor genes may share the same requirement, i.e., two hits are necessary to inactivate the gene function.

Growth inhibition by phospholipase C inhibitor peptides of colorectal carcinoma cells derived from familial adenomatous polyposis

We reported previously the enhanced phosphoinositide metabolism and constitutive activation of phosphoinositide-specific phospholipase C (PLC) in two colorectal carcinoma cell lines, KMS-4 and KMS-8, derived from familial adenomatous polyposis patients. To study the physiological role of enhanced PLC activity in these cells, we analyzed the effect of PLC inhibitor (PCI) peptides on their growth and cell cycle. N-Myristoylated PCI peptide, myr-PCI(Y), originally developed based on the PCI sequence of PLC-gamma 2, inhibited activity of purified PLC isoforms in vitro. When myr-PCI(Y) was added to KMS-4 and KMS-8 cultures, it suppressed the production of inositol trisphosphate, DNA synthesis, and cell growth, all of which were induced by serum in both KMS-4 and KMS-8 cells. The number of colonies grown in soft agar was also reduced significantly by treating KMS-8 cells with myr-PCI(Y) peptide. Flow cytometry analysis with propidium iodide labeling revealed marked decreases in the percentage of KMS-8 cells in S phase and increases in G0-G1 by the addition of myr-PCI(Y). On the other hand, myr-PCI(F), in which two of the tyrosine residues in myr-PCI(Y) are replaced by phenylalanine and which does not inhibit phosphatidylinositol 4,5-bisphosphate-hydrolyzing activity in vitro, did not significantly inhibit either inositol trisphosphate production or cell growth. These results indicate that the activation of PLC is essential for growth and the transformed properties of these colorectal carcinoma cells.

Microsatellite instability in gastric cancer prone families

We examined for germ-line p53 mutations and microsatellite instability in three gastric cancer patients who had family histories of gastric cancer aggregation. Although no germ-line p53 mutation was detected in these three cases, the replication error (RER) phenotype was observed in two of them. One base deletion in the sequence of ten repeating adenines of the type II transforming growth factor-beta receptor gene was detected in one of these two cases. Furthermore, there were young patients of 50 years and downward in their families. Therefore, it is possible that inherited disorders in mismatch repair systems contribute to high susceptibility to gastric cancers in these families.

Sequential activation of MAP kinase cascade by angiotensin II in opossum kidney cells

Angiotensin II (Ang II) is a potent regulator of proximal tubule functions, including transport, metabolism, and cell proliferation. The opossum kidney (OK) cell line is a useful model of renal proximal tubule. Mitogen-activated protein (MAP) kinases are rapidly phosphorylated and activated in response to various agonists. We investigated Ang II effects on serine/threonine kinase cascades in OK cells. The major findings of the present study are that Ang II stimulated MAP kinase kinase (MAPKK), MAP kinase (MAPK), and S6 kinase activities, and that it increased phosphorylation of Raf-1 kinase and p42 MAP kinase in OK cells. These stimulations of kinases were dose-dependent (from 10(-6) to 10(-11) M). The time course of activation was sequential; the peak stimulation was reached at 5 to 10 minutes for Raf-1 kinase, MAPKK and MAPK, and at 20 minutes for S6 kinase. The activation of MAPK was inhibited by approximately 70% with prolonged 24-hour PMA pretreatment or in the presence of calphostin C or H-7. Tyrosine kinase inhibitors (genistein and herbimycin) did not inhibit AngII-induced MAPK activity. This activation of MAPK was also inhibited via AT1 receptor antagonist, Dup753 and pertussis toxin. This evidence suggests that the activation of serine/threonine cascades by Ang II is largely dependent on PMA-sensitive PKC, and is not dependent on tyrosine kinase and pertussis toxin.

Mutations of the transforming growth factor-beta type II receptor gene and genomic instability in hereditary nonpolyposis colorectal cancer

To determine the relation between the mutation of the TGF-beta type II receptor gene and genomic instability in the tumorigenesis of hereditary nonpolyposis colorectal cancer (HNPCC), we screened genomic DNA of 38 tumors from 25 HNPCC patients, 15 colorectal cancers from familial adenomatous polyposis patients, and 8 sporadic endometrial cancers, in two areas containing a (A)10 repeat or a (GT)3 repeat of the gene. Seventeen of the 24 (71%) genomic instability-positive HNPCC tumors carried one or two A deletions in the (A)10 repeat, while none of the 14 genomic instability-negative tumors did. These deletions inactivate the receptor through a frameshift mutation and the resultant protein truncation. No mutation was detected in the (GT)3 repeat sequence, but we found a missense mutation of codon 537 in the same area in one tumor. One A deletion was also detected in a genomic instability-positive sporadic endometrial cancer, but none in familial adenomatous polyposis tumors. No mutations were detected in the corresponding normal cells of these cases, indicating a somatic mutation. These data suggest that the TGF-beta type II receptor gene is a major target of genomic instability in HNPCC tumorigenesis.

Effect of total adipose weight and systemic hypertension on left ventricular mass in children

To investigate the effect of obesity and hypertension on left ventricular (LV) mass in children, we performed echocardiography and measured the height, weight, and blood pressure of 267 healthy children (145 boys and 122 girls) aged 12 years. The percentage of body fat was estimated using bioelectric impedance to derive the total adipose weight and lean body weight. End-diastolic measurements of LV parameters were obtained from M-mode echocardiograms. The LV mass was calculated by using the formula of Devereux et al. A strong positive correlation was demonstrated between non-normalized LV mass and height or other measures of body size. Systolic blood pressure was weakly correlated with non-normalized LV mass in boys. The impact of height on LV mass differed between boys and girls. Thus, different allometric formulas to normalize the LV mass for height were determined, using the height to the 3.1 and 1.9 powers for boys and girls, respectively. Regression analysis revealed that only total adipose weight affected the normalized LV mass, and that the effect of total adipose weight was greater in girls than in boys. The obese children had a significantly greater normalized LV mass than the nonobese children. The increase in the LV mass due to obesity appeared to be eccentric, because of the lack of an association between the indices of obesity and relative wall thickness. Our data indicate that appropriate normalization of LV mass is necessary for each study population, and that LV hypertrophy due to obesity begins in childhood.

Polymorphisms and probable lack of mutation in a human mutT homolog, hMTH1, in hereditary nonpoliposis colorectal cancer

The human MTH1 gene, a homolog of the E. coli mutator gene mutT, encodes 8-oxo-dGTPase that degrades a mutagenic substrate for DNA synthesis. To determine whether this gene is associated with hereditary nonpolyposis colorectal cancer (HNPCC), we examined the hMTH1 sequence in 32 HNPCC cases by means of polymerase chain reaction-single strand conformation polymorphism and sequencing analyses. Three different DNA variants were identified in normal and the corresponding tumor DNA. The first variant, a G to A transition at codon 83, changes valine to methionine and was detected in 9 HNPCC cases. The same change was detected in 5 of 30 unrelated healthy individuals, suggesting that it is not associated with a marked HNPCC predisposition. The second variant is a silent C to T transition at codon 119. Another C to T transition at 31 bp upstream of the beginning of exon 4 was also found. However, specific mutations in hMTH1 were detected in neither normal nor tumor cells from HNPCC patients. These results indicate that hMTH1 is not directly involved in HNPCC.

AVP inhibits EGF-stimulated MAP kinase cascade in Madin-Darby canine kidney cells

We investigated the effects of epidermal growth factor (EGF) and arginine vasopressin (AVP) on Raf-1-MAP kinase cascade, including Raf-1-kinase (Raf-1-K), MAP kinase kinase (MAPKK), MAP kinase (MAPK) and S6 kinase (S6K) in Madin-Darby canine kidney (MDCK) cells. In a dose-dependent manner (10(-10) M to 10(-6) M), EGF increased autophosphorylation of Raf-1-K and activated MAPKK, MAPK and S6K. Sequential activation of these kinases was indicated by their peak times of activation (Raf-1-K 5 min; MAPKK 10 min; MAPK 15 min; and S6K 30 min). AVP (10(-9) M to 10(-6) M) inhibited EGF-stimulated MAP kinase cascade. 8-Bromo-cyclic AMP (cAMP) could mimic the inhibitory effect of AVP on EGF-stimulated MAP kinase cascade. These results were confirmed using H-89, an inhibitor of protein kinase A (PKA) that blocked the effect of AVP on EGF-stimulated MAPK activity. We conclude that AVP inhibits EGF-stimulated Raf-1-K, MAPKK, MAPK, and S6K activity via cAMP in MDCK cells. Our results indicate that MAP kinase cascade may play an important role in integrating the effects of AVP and EGF on distal tubule function.

Forced expression of YL-1 protein suppresses the anchorage-independent growth of Kirsten sarcoma virus-transformed NIH3T3 cells

The YL-1 gene, encoding a novel nuclear protein with transcription factor-like features, has been isolated from the human chromosome 1q21, one of the regions supposedly carrying a transformation suppressor gene(s) for Kirsten sarcoma virus-transformed NIH3T3 (DT) cells. To test the suppressive activity of the YL-1 gene product, we forced the expression of human YL-1 cDNA in DT cells. The anchorage-independent growth (colony-forming ability in soft agar medium) was markedly suppressed in cells highly expressing the exogenous human YL-1 protein. Moreover, the soft agar clones, which were rarely originated from these cells, expressed reduced levels of exogenous YL-1 or none, with or without the loss/rearrangement of the introduced cDNA. In control experiments, cells carrying an introduced vector alone or an antisense-strand expression plasmid grew in soft agar as efficiently as parental DT cells. In contrast to the suppression of anchorage-independent growth, the forced expression of YL-1 did not effect the transformed phenotypes in adherent culture and tumorigenicity in nude mice. These findings not only indicated that the YL-1 protein functions as a transformation suppressor, but also suggest that it may be important for elucidating anchorage independence under separate genetic control from other transformed phenotypes.

An investigation of preferable taper and thickness ratios for cast circumferential clasp arms using finite element analysis

This study used a two-dimensional finite element method to investigate the preferred design for a cast circumferential clasp. Finite element models of the clasp arm with the constant flexibility were constructed, the stress was calculated, and the effects of taper and cross-sectional shape on stress were evaluated. The clasp arm with the taper of 0.8 showed less stress than those with other tapers, and the thinner and wider arms showed less stress than those with other cross-sectional dimensions. These results suggest that the use of the preformed clasp-pattern with a taper of 0.8 is preferable for reducing fatigue and/or permanent deformation of the clasp arm.