PubMed Health⌕ Search

Biomedical subjects

N Tomita

Publications and source records attributed to N Tomita.

At least 19 recordsLinked to original sources
PubMed1996

Mutations of the transforming growth factor beta type II receptor gene and microsatellite instability in gastric cancer.

Forty-three sporadic gastric cancers were analyzed with regard to whether mutations of simple repeated sequences in the transforming growth factor beta type II receptor (TbetaR-II) gene are associated with microsatellite instability (MSI) and gastric carcinogenesis. In 12 of the 43 cancers (28%), MSI was observed at least at 1 of the 2 microsatellite loci. Frameshift mutations of the TbetaR-II gene, all of which were 1 base deletion of 10 adenine repeats, were detected in 3 of 6 cancers, with MSI at 2 loci. However, mutations were not detected in 6 cancers, with MSI only at 1 locus and 31 cancers without MSI. Moreover, microanalysis in these cases revealed that the mutant-type alleles of TbetaR-II were invariably common in different areas within the tumor, in contrast to the markedly variable alleles of microsatellite loci. Our results suggest that frameshift mutation of the TbetaR-II gene may be a critical event associated with MSI and may contribute to carcinogenesis of the stomach. One of the possible mechanisms of escape from growth control by TGFbeta during gastric carcinogenesis could involve frameshift mutations of the TbetaR-II gene caused by DNA replication errors.

Adenine↗
PubMed1996

Sustained transgene expression by transfection of renin gene into liver of neonates.

Although transfection of renin gene into adult liver resulted in increased blood pressure (BP) for 1 week, sustained transgene expression must be considered to produce a continuous hypertensive animal. We hypothesized that gene transfer into neonatal rats would result in long-term transgene expression, given with highly replicating hepatocytes in neonates. Initially, chloramphenicol acetyltransferase (CAT) vector was transfected into the liver of 1-day-old rats. Immunohistochemical staining showed positive staining of CAT throughout the liver. Therefore, we transfected renin vector to study biological effects. At 2, but not 4 and 8, weeks, a significant increase in plasma angiotensin II concentration was observed in rats transfected with renin vector. Expression of renin mRNA in the liver transfected with renin vector could be detected at least up to 6 weeks, while no significant changes in BP were observed. These results demonstrated that in vivo gene transfer into the neonatal liver resulted in sustained transgene expression, suggesting the potential use of in vivo gene transfer as a tool to produce a novel model.

Aging↗
PubMed1996

Pure red cell aplasia after major ABO-incompatible bone marrow transplantation: two case reports of treatment with recombinant human erythropoietin.

A 34-year-old man with acute myelocytic leukemia (AML: MO) and a 32-year-old woman with AML: M2 developed pure red cell aplasia (PRCA) after receiving a major ABO incompatible bone marrow transplant (BMT). The first patient responded to recombinant human erythropoietin (rhEPO) therapy, while the second did not. The second patient also received methylprednisolone (m-PSL) but developed reticulocytosis and hemolysis after the administration of m-PSL. Plasmapheresis was then performed and the patient promptly recovered from hemolysis and PRCA. We conclude that close attention must be paid when treating PRCA following major ABO-incompatible BMT with rhEPO and m-PSL, as there is always the potential for massive hemolysis.

ABO Blood-Group System↗
PubMed1996

Occult macular dystrophy.

PURPOSE: Occult macular dystrophy is a hereditary macular dystrophy without any visible abnormality of the fundus or abnormality indicated by fluorescein angiography even when visual acuity is decreased. Normal full-field electroretinogram in both cone and rod components with abnormal focal macular cone electroretinogram is the key to diagnosing this disorder. The purpose of this study was to identify the function of the macular rods and to provide detailed clinical findings in occult macular dystrophy. METHODS: Thirteen patients from eight families were examined. The fundi of 12 patients were essentially normal (occult macular dystrophy), and the oldest patient in one family disclosed bull's eye maculopathy. In the 12 patients, including the patient with bull's eye maculopathy, the profiles of cone and rod absolute thresholds were performed across the 60-degree horizontal meridian of the posterior pole. RESULTS: All 12 patients showed cone sensitivity loss only in the macular area. Six relatively young patients revealed normal rod sensitivity, whereas six older patients showed borderline rod sensitivity or abnormal rod sensitivity in the macular area. CONCLUSIONS: The pathology of occult dystrophy involves either only the macular cone system or macular cone and rod systems without any visible abnormality. This difference of the pathology suggests a different clinical entity or a different stage of occult macular dystrophy.

Adolescent↗
PubMed1996

Human herpesvirus-6-associated exanthema in a patient with acute lymphocytic leukaemia.

SUMMARY: We report the first case of human herpesvirus-6 (HHV-6) associated exanthema in a patient with acute lymphocytic leukaemia (ALL). We analysed DNA extracted from an exanthematous lesion using the polymerase chain reaction (PCR). DNA was positive for HHV-6 but negative for herpes simplex virus, varicella zoster virus, and cytomegalovirus. Immunohistochemical staining of the skin with monoclonal antibody against (HHV-6 confirmed the infection. The possibility of HHV-6 infection should be considered when an atypical skin rash is seen in patients with ALL.

Adult↗
PubMed1996

Role of transcriptional cis-elements, angiotensinogen gene-activating elements, of angiotensinogen gene in blood pressure regulation.

Results of recent genetic studies suggest that the angiotensinogen gene is a possible determinant of hypertension. Using antisense technology, we demonstrated that generation of circulating angiotensinogen is a rate-limiting step in blood pressure regulation. In the present study, we examined how the angiotensinogen gene is regulated in vivo. The transcriptional cis-elements, angiotensinogen gene-activating elements (AGE) 2 and 3, have been reported to regulate angiotensinogen production in human hepatocytes in vitro. To determine the critical transcriptional regulator of angiotensinogen production in vivo, we used synthetic double-stranded oligodeoxynucleotides (ODN) as "decoy" cis-elements to block the binding of nuclear factors to promoter regions of the targeted gene, resulting in the inhibition of gene transactivation. Here we examined whether AGE 2 and AGE 3 in the promoter region of the angiotensinogen gene have a pivotal role in hepatic angiotensinogen production in vivo. Hepatic angiotensinogen mRNA was decreased by the transfection of AGE 2 but not mismatched decoy ODN. Transfection of decoy but not mismatched ODN against AGE 2 resulted in a transient decrease in blood pressure of spontaneously hypertensive rats (SHR), accompanied by a reduction in plasma angiotensinogen and angiotensin II levels. In contrast, transfection of AGE 3 decoy ODN had little effect on blood pressure. Overall, our results demonstrate that transfection of decoy ODN against AGE 2, but not against AGE 3, of the angiotensinogen gene resulted in a transient decrease in high blood pressure of SHR, suggesting that the transcriptional cis-element AGE 2, rather than AGE 3, has an important role in blood pressure regulation through the control of circulating angiotensinogen.

Angiotensinogen↗
PubMed1996

[Ganciclovir prophylaxis for cytomegalovirus interstitial pneumonitis after allogeneic bone marrow transplantation].

We evaluated the efficacy of ganciclovir to prevent the development of cytomegalovirus interstitial pneumonitis (CMV-IP) in patients with bone marrow transplants. Of 35 patients enrolled in this study, 33 were seropositive for CMV or had seropositive donors, and two were seronegative before transplant but were positive for CMV examined by polymerase chain reaction (PCR) on days 30-37. Ganciclovir was given at a dose of 250 mg/body daily from day 30-37 to day 70. Blood, throat swabs, urine and bronchoalveolar-lavage fluid (BALF) were screened for CMV by PCR on days 30-37, 70 and 100. CVM-IP developed in two of 35 patients (5.7%) who received ganciclovir for prophylaxis, as compared with six of 39 historical controls who did not receive ganciclovir. A significant reduction of CMV detection by PCR in blood, throat swabs, and BALF was observed after administration of ganciclovir, on day 70. The incidence of neutropenia, thrombopenia and renal impairment in the study period showed no difference between the study group and the historical control. Early prophylactic use of ganciclovir appears to reduce the risk of CMV disease in allogeneic transplant recipients with positive serology or positive CMV-PCR.

Adolescent↗
PubMed1996

In vivo gene transfer of insulin gene into neonatal rats by the HVJ-liposome method resulted in sustained transgene expression.

In Many areas of disease such as homozygous familial hypercholesterolemia, no known effective therapy exists. The time is ripe for the introduction of gene therapy for the management of incurable disorders. However, for clinical gene therapy it is necessary to establish an efficient and non toxic gene delivery system. Recently, we have developed a gene delivery system mediated by Sendai virus as a potential means of gene therapy. However, this HVJ-liposome method has some disadvantages: (1) transient transgene expression; and (2) no integration. In gene therapy, it is desirable for transgenes to be expressed for as long as possible. To deal with this issue, we hypothesized that gene transfer into newborn animals would result in sustained expression of transgene. Our results demonstrated that transgene expression in liver was subsequently sustained for at least up to 8 weeks, as detected by reverse transcriptase PCR and radioimmunoassay, while our previous studies documented that transgene expression in adult animals disappeared within 2 weeks. Interestingly, we detected the presence of transgene in the host genomic DNA extracted from the nuclei of hepatic cells assessed by PCR. These findings provide new important information for gene therapy, although the mechanisms of sustained transgene expression are not clear.

Aging↗
PubMed1996

A new technique for exposing Calot's triangle during laparoscopic surgery: usefulness of extracorporeal lifting of the round ligament and gallbladder.

We developed a maneuver for holding and lifting the intraperitoneal organs from the extracorporeal side using a new instrument, the leading bar, by which we could guide the tape or the thread to the outside of the abdomen. In the case of cholecystolithiasis with a thickened wall or a stone stuck in the neck, we lifted the round ligament and gallbladder for better exposure of Calot's triangle, using the tape or thread through the abdominal wall to the extracorporeal side, and then clamped them with Kocher's forceps. With this technique, a good view of Calot's triangle was maintained so that the surgeon could expose the cystic duct easily and safely using both hands.

Cholangiography↗
PubMed1996

[Low-grade non-Hodgkin's lymphoma: intensive combined chemotherapy].

The efficacy of various combination chemotherapies employed for the 37 patients with low-grade non-Hodgkin's lymphoma between 1981 and 1994 was evaluated retrospectively. The overall survival at 5 years was 68%. The 5-year survival of the 27 patients achieving complete response (CR) was 87%, which was significantly higher than that of 9 patients with partial response (p = 0.0005). The CR rate of stage III and IV patients was 64% for the 22 patients treated with ACOMP-B (D), and was 38% for 8 others treated with milder chemotherapy regimens including VEPA. The 22 advanced stage patients had a 5-year survival of 88% after the treatment with ACOMP-B (D) and 69% of them remained free of disease at 5 years. In this group no relapse occurred beyond 1.6 years after treatment. These findings suggest a possible role of third generation chemotherapy in the treatment of patients with advanced-stage low-grade non-Hodgkin's lymphoma.

Adult↗
PubMed1996

[RB gene expression in gastrointestinal tract].

pRB, the retinoblastoma tumor suppressor gene product, regulates the cell cycle at G1/S transition negatively. Many cell cycle regulators modulate pRB function through its phosphorylation status. G1 cyclins (cyclin D, E)/cyclin-dependent kinases (cdk2, 4) inactivates pRB through its phosphorylation, while p21 (WAF1) and p16 inhibit cdks. In several kinds of cancer, Rb gene alteration or functional inactivation of pRB has been reported. In esophageal cancer, loss of heterozygosity of Rb gene and cyclin D gene amplification were frequently detected. But in gastric and colorectal cancer, Rb gene loss or deletion has been shown to be rare. In this study we investigated the expression of pRB, G1 cyclins, cdks and cdk-inhibitors in adenoma-carcinoma sequence of colorectum. And we compared the phosphorylation status of pRB in colorectal normal mucosa and cancer tissue. In adenoma only cyclin D and E were overexpressed but not cdks. In cancer in adenoma pRB and cdk2 were overexpressed with high frequency, and cdk4 overexpression was detected in advanced cancer. p16 overexpression was detected in almost all cancers, but in contrast p21 overexpression was rare event. Comparative study showed that pRB-positive cancer cells also expressed both cdc2/cdk2 and cyclin E. Densitometric analysis revealed that in advanced cancer pRB was hyperphosphorylated compared with normal mucosa. These results indicate that overexpression of cyclin D/cdk4 and cyclin E/cdk2 would phosphorylate pRB, and insufficient expression of p21 may accelerate pRB inactivation.

Cell Cycle↗
PubMed1996

[Cyclin D, CDK4 and p16 expression in colorectal cancer].

G1/S transition of cell cycle is regulated by G1 cyclins/cyclin-dependent kinases (CDKs) and their inhibitors. Cyclin D/CDK4 complex phosphorylates retinoblastoma gene product and p16 inhibits CDK4 in competition with cyclin D. Aberrant expression of these proteins may deregulate cell proliferation and moreover may lead to tumor formation and progression. In this study we examined the expression of cyclin D, CDK4 and p16 in adenoma-carcinoma sequence of colorectum. Immunohistochemical staining revealed that cyclin D was overexpressed in 55 of 66 (83%) adenomas, 8 of 8 (100%) carcinomas in adenoma (CIAs), 26 of 45 (58%) advanced carcinomas and even in hyperplastic mucosa. CDK4 was overexpressed in 0 of 52 (0%) adenomas, 0 of 14 (0%) CIAs and 39 of 45 (87%) advanced carcinomas, but not in hyperplastic mucosa. p16 was overexpressed in only 5 of 52 (10%) adenomas, 10 of 14 (71%) CIA and 59 of 60 (98%) advanced carcinomas, but not in hyperplastic mucosa. And comparative study of CDK4 and p16 showed that CDK4-positive cancer cells also expressed p16. Western blot analysis also revealed that primary regions of advanced colorectal cancer tissues showed 4.61, 3.30, 1.65 and 8.03-fold overexpression on the average in cyclin D1, cyclin D2, CDK4 and p16 respectively. These results indicate that both cyclin D and CDK4 may contribute to phosphorylation of pRB. p16 overexpression would be induced as a brake at G1/S transition through pRB phosphorylation by CDK4 overexpression in advanced colorectal carcinomas.

Adenoma↗
PubMed1995

Evaluation of vascular compliance and vasoconstrictive reactions in amputated hindlimbs of rats.

The vascular compliance and the contractility of vascular smooth muscle of preserved, amputated hindlimbs of rats were evaluated using a fresh blood extracorporeal circulatory system. Vascular compliance was measured under physiologic circulatory conditions (blood pressure of the amputated limb was maintained at 80-150 mm Hg [10-20 kPa]) and found not to differ significantly from that of freshly amputated limbs after storage at 4 degrees C for 12 hours. However, after more than 24 hours of storage at 4 degrees C, the vascular compliance decreased significantly (p < 0.01). To evaluate the contractility of vascular smooth muscle, the arterial blood pressure in the amputated limbs was transiently increased with injections of norepinephrine. The contractility could be preserved for at least 12 hours at 4 degrees C; however, it decreased markedly after more than 24 hours. The vascular compliance and vasoconstrictive reactions of the amputated limbs were maintained for at least 12 hours at 4 degrees C.

Amputation, Surgical↗
PubMed1995

Expression of phospholipases gamma 1, beta 1, and delta 1 in primary human colon carcinomas and colon carcinoma cell lines.

The levels of expression of phosphoinositide-specific phospholipase Cs (PLCs) were examined in a series of primary human colon carcinomas and in eight colon carcinoma cell lines by using monoclonal antibodies and cDNA probes for PLC gamma 1, PLC beta 1, and PLC delta 1. Western and northern blot analyses of PLC gamma 1 revealed elevated expression of this isozyme at both the protein and mRNA levels in most tumors when compared with paired adjacent normal mucosa samples (in 11 of 13 pairs in the western blots and 8 of 9 pairs in the northern blots). On the other hand, decreased levels of the PLC delta 1 protein were seen in most colon carcinomas (12 of 13 paired samples). The levels of PLC beta 1 protein were too low to detect possible differences between the carcinoma and normal mucosa samples. Relatively high expression of PLC gamma 1 was found in almost all of the eight human colon carcinoma cell lines at both the protein and mRNA levels. Only weak expression of PLC beta 1 was detected in these cell lines, by both western and northern blot analyses, and PLC delta 1 protein was not detected in any of the carcinoma cell lines. These findings provide evidence that colon carcinomas display altered expression of individual isoforms of PLCs and suggest that increased expression of PLC gamma 1 may play an important role in colon carcinogenesis.

Adult↗
PubMed1995

Coexpression of cdk2/cdc2 and retinoblastoma gene products in colorectal cancer.

The retinoblastoma gene (Rb gene) is a tumour-suppressor gene and its product (pRB) is known to act as a negative regulator of the cell cycle. Although lack of pRB expression resulting from gene alterations is considered to be responsible for the genesis of several human malignancies, increased expression of pRB has been demonstrated in a majority of colorectal cancer cases. In the present study, we investigated the expression of pRB as well as that of its related kinases, cdk2 and cdc2, in colorectal cancer, since these kinases have been reported to phosphorylate and inactivate pRB. Western blot analysis revealed that colorectal cancer expressed higher levels of cdk2 and cdc2 than did normal mucosa and that the ratio of the hyperphosphorylated form of pRB was higher in colorectal cancer. Furthermore, immunohistochemical studies showed that cdk2/cdc2 was expressed exclusively in the cancer cells positive for pRB. These results suggest that an increase in the expression of cdk2/cdc2 in colorectal cancer may have prevented pRB from braking the cell cycle through phosphorylation.

Blotting, Western↗
PubMed1995

Effect of an antihypertensive drug on brain angiotensin II levels in renal and spontaneously hypertensive rats.

1. Although numerous studies suggest that brain angiotensin (AII) may play an important role in the regulation of blood pressure, it is still unclear what factors may influence brain AII. In this study, we hypothesized that brain AII is influenced by circulating factors. To investigate the role of blood pressure and plasma AII in brain AII level, we studied the effect of an antihypertensive drug on brain AII in two-kidney, one-clip (2K1C) and spontaneously hypertensive (SHR) rats. 2. Hydralazine (20 mg/kg per day) and vehicle (water) were given to 2K1C rats between 2 and 6 weeks after operation and SHR for 4 weeks. In addition, vehicle was applied to sham operated rats and Wistar-Kyoto (WKY) rats. Brain and plasma AII was measured by a highly sensitive radioimmunoassay coupled with high performance liquid chromatography. 3. Hydralazine treatment effectively lowered blood pressure to the same level of sham-operated and WKY rats. 2K1C rats showed significantly higher plasma AII than sham rats, but hydralazine treatment did not show any change in plasma AII. Brain AII in the hypothalamus region of 2K1C rats showed a significantly higher level than sham rats. Interestingly, hydralazine treatment diminished this increase in brain AII. In contrast, SHR showed higher brain AII levels in the hypothalamus, brainstem and cerebellum than in WKY rats, whereas there was no significant change in plasma AII concentration between SHR and WKY rats. In contrast to the results found in 2K1C rat experiments, hydralazine treatment failed to decrease brain AII levels despite lowered blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1995

Transient decrease in high blood pressure by in vivo transfer of antisense oligodeoxynucleotides against rat angiotensinogen.

The renin-angiotensin system plays an important role in blood pressure regulation. Angiotensinogen, which is mainly produced in the liver, is a unique component of the renin-angiotensin system, because angiotensinogen is only known as a substrate for angiotensin I generation. It is unclear whether circulating angiotensinogen is a rate-limiting step in blood pressure regulation. Recent findings of genetic studies and analyses suggest that the angiotensinogen gene may be a candidate as a determinant of hypertension. To test the hypothesis that angiotensinogen may modulate blood pressure, we transfected antisense oligonucleotides against rat angiotensinogen into the rat liver via the portal vein using liposomes that contain viral agglutinins to promote fusion with target cells, a technique that has been reported to be highly efficient. Transfection of antisense oligonucleotides resulted in a transient decrease in plasma angiotensinogen levels in spontaneously hypertensive rats from day 1 to day 7 after the injection, consistent with the reduction of hepatic angiotensinogen mRNA. Plasma angiotensin II concentration was also decreased in rats transfected with antisense oligonucleotides. Moreover, a transient decrease in blood pressure from day 1 to day 4 was observed, whereas transfection of sense and scrambled oligonucleotides did not result in any changes in plasma angiotensinogen level, blood pressure, or angiotensinogen mRNA level. Overall, our results demonstrate that transfection of antisense oligonucleotides against rat angiotensinogen resulted in a transient decrease in the high blood pressure of spontaneously hypertensive rats, accompanied by a decrease in angiotensinogen and angiotensin II levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗