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H Higashi

Publications and source records attributed to H Higashi.

At least 19 recordsLinked to original sources
PubMed1995

Differences in substrate specificity between Cdk2-cyclin A and Cdk2-cyclin E in vitro.

Cyclin-dependent kinase 2 (Cdk2), when bound to either cyclin A or cyclin E, recognizes the Ser/Thr-Pro-X-basic amino acid (motif A) as a phosphorylation site. In this study, we designed several peptides based on motif A and examined the substrate specificity of Cdk2-cyclin A and Cdk2-cyclin E using these peptides. Peptides containing a proline residue in the sequence Pro-X-Thr-Pro-X-basic amino acid (motif B) had higher affinity for both Cdk2 complexes than peptides containing motif A. Furthermore, differences in substrate affinity between the two Cdk2 complexes were caused by a proline residue adjacent to or three positions before the threonine residue. Similarly, the presence of different basic amino acids in motif B also had different effects on affinity for each complex. We demonstrate the possibility that the substrate specificity of Cdk2 bound to cyclin might be regulated by the species of cyclin.

Amino Acid Sequence↗
PubMed1995

The interactions of E2F with pRB and with p107 are regulated via the phosphorylation of pRB and p107 by a cyclin-dependent kinase.

It has been postulated that the product (pRB) of the retinoblastoma gene dissociates from the E2F-pRB complex upon phosphorylation by cyclin-dependent kinase(s) (cdk). However, there is no direct evident for the regulation of formation of the E2F-pRB complex via phosphorylation by purified cdk. Therefore, we investigated the regulation of formation of this complex by phosphorylation using pRB and purified cyclin A-cdk2, cyclin E-cdk2 or cyclin D1-cdk4. Purified pRB was incubated with nuclear extracts prepared from pRB-defective cells and then subjected to gel mobility shift assays. We confirmed that unphosphorylated pRB associated with various types of E2F but pRB has been phosphorylated by cyclin A-cdk2 did not. We found that E2F-pRB complexes were disrupted as a consequence of phosphorylation by cyclin A-cdk2, and the levels of the free forms of E2Fs increased. We also found that not only the E2F-pRB complexes but also the E2F-p107 complexes were disrupted upon phosphorylation by cyclin A-cdk2. Furthermore, E2F-pRB complexes were disrupted through phosphorylation by cyclin D1-cdk4 and cyclin E-cdk2, as well as by cyclin A-cdk2. These results clearly demonstrate that the phosphorylation of pRB and p107 by cdks regulates the formation of complexes between E2F and pRB or p107.

Base Sequence↗
PubMed1995

A variant form of cyclin-dependent kinase 2 (Cdk2) in a malignantly transformed rat thyroid (FRTL-Tc) cell line.

Cyclin-dependent kinase 2 (Cdk2) controls the transition from the G1 to the S phase in the mammalian cell cycle. We found by immunoblotting that anti-Cdk2 antibodies recognize three Cdk2 proteins (of 33, 34 and 39 kDa) in FRTL-5 and FRTL-Tc cells (malignantly transformed FRTL cells). Although 33 kDa protein is a phosphorylated form of 34 kDa protein previously reported, the nature of 39 kDa protein is unknown. In order to determine the nature of this protein, we screened a FRTL-5 cDNA library. Two cDNA clones of the rat homologue (rat Cdk2-alpha and -beta) of human Cdk2 were isolated. The open reading frame of rat Cdk2-alpha cDNA encoded a protein with 428 amino acids and has a high degree of conservation with human Cdk2. The calculated molecular weight of Cdk2-alpha protein is 33892 Da. The rat Cdk2-beta cDNA was identical to Cdk2-alpha cDNA except that it had extra 144 bp; this coincided with insertion of 48 amino acids into Cdk2-alpha protein between Met 196 and Val 197. The calculated molecular weight of Cdk2-beta protein is 39087 Da. Northern blot analysis indicated that the sizes of rat Cdk2-alpha and -beta mRNAs are approximately 2.5 kb and 3.0 kb, respectively. Partial proteolytic mapping showed that Cdk2-beta gene product is 39 kDa Cdk2 in the immunoblotting. We also found that Cdk2-beta protein binds to cyclin A and suc1 proteins. During G1-S phase in FRTL-Tc cells, Cdk2-alpha protein level is constant, but is gradually phosphorylated. In contrast, the level of Cdk2-beta protein increases through the S phase and decreases at the early G2 phase. These results suggest that a variant form of Cdk2 protein might be required for entry into the S phase of the cell cycle in FRTL-Tc cells.

Amino Acid Sequence↗
PubMed1995

Phosphorylation of E2F-1 by cyclin A-cdk2.

Transcription factor E2F-1 has a putative consensus sequence for phosphorylation by cyclin dependent kinase (Ser-Pro-X-Lys/Arg). Therefore, we studied the phosphorylation of E2F-1 in vivo and in vitro and its biological functions. E2F-1 was prepared by immunoprecipitation with anti-E2F-1 antibody from IMR32 lysates and was effectively phosphorylated by human cyclin A-cdk2 which was expressed in insect cells using baculovirus system. GST-E2F-1 was phosphorylated by cyclin A-cdk2 more efficiently than by cyclin E-cdk2. Cyclin D1-cdk4 phosphorylated pRB but scarcely phosphorylated GST-E2F-1 or H1 histone. The 60 kd protein precipitated with anti-E2F-1 antibody was phosphorylated in vivo. Phospho-peptide mapping indicated that its cleavage profile was identical with that of E2F-1 phosphorylated by cyclin A-cdk2 in vitro. This 60 kd protein, which is likely to be E2F-1, was not phosphorylated during the G0 and early G1 phase. Phosphorylation of E2F-1 began from the S phase while phosphorylation of pRB started nearly at G1/S. The in vivo phosphorylation of E2F-1 was inhibited by butyrolactone I, a cyclin-dependent kinase inhibitor (Kitagawa et al., 1993, Oncogene, 8, 2425-2432). The binding of E2F-1 to E2 promoter was found to be reduced by phosphorylation of E2F-1 by cyclin A-cdk2, suggesting that phosphorylation of E2F-1 may induce shut off of gene expression at the transcriptional level. These results suggest that E2F-1 is phosphorylated by cyclin A-cdk2 in the S phase in vivo as well as in vitro and that its phosphorylation by cyclin A-cdk2 may modulate its activity.

Baculoviridae↗
PubMed1995

Production of human monoclonal antibodies to i blood group by EBV-induced transformation: possible presence of a new glycolipid in cord red cell membranes and human hematopoietic cell lines.

To study the differentiation-associated glycolipid two anti-i mAb producers, GL-1 and GL-2, were established from the combination of EBV-induced transformation of normal PBL and immune lysis of fluorescent dye-trapped liposome-containing bovine i-active glycolipid. The mAb GL-1 reacted with both sialosylparagloboside and pentahexosyl ceramide and the bovine i-active glycolipid whereas mAb GL-2 reacted only with the bovine i-active glycolipid in LILA. Both mAbs cold-agglutinate human cord red cells but not adult red cells. However, unexpectedly, the majority of the reactivity of these mAbs in human cord red cells on TLC was not identical to the i-active glycolipid. The GL-1 antigenic substance is considered to be a glycolipid distinct from the i-active glycolipid because the immunoreactivity was canceled with endoglycoceramidase which cleaves a linkage between the oligosaccharide and ceramide. Based on complement cytolysis with the mAb, 15 hematopoietic cell lines and normal peripheral lymphocytes were screened for susceptibility to the mAbs. A Burkitt lymphoma cell line, Ramos, was most sensitive among those tested, and BJA-B, Daudi, Namalwa in the B cell lines, TALL-1, Jurkatt in the T-cell lines and HL-60 in the non-lymphoid cell lines were sensitive whereas normal lymphocytes or other 8 cell lines were not. An immunoreactive spot with the same Rf with cord red cells was also detected in sensitive cell lines. The possible presence of a new glycolipid antigen determined from the mAb and related to the differentiation of hematopoietic cells was speculated.

Antibodies, Monoclonal↗
PubMed1995

Increased prostacyclin content in gastric mucosa of cirrhotic patients with portal hypertensive gastropathy.

Plasma levels and gastric mucosal contents of prostaglandin (PG) E2 and prostacyclin were determined in cirrhotic patients with portal hypertensive gastropathy (PHG), in cirrhotic patients without PHG and in healthy controls. PGE2 and 6-keto-PGF1 alpha (a stable metabolite of prostacyclin) levels were measured in 30 cirrhotic patients and 10 controls, using radioimmunoassay. Of 30 cirrhotics, 13 had PHG of the fundus and the corpus. Plasma concentrations of 6-keto-PGF1 alpha in the cirrhotic patients were significantly higher than in the controls (p < 0.01), but there was no significant difference between cirrhotics and controls with regard to plasma levels of PGE2. The gastric mucosal contents of 6-keto-PGF1 alpha in the fundus was significantly higher in cirrhotics with PHG than those without PHG (p < 0.05) and controls (p < 0.01). However, the gastric mucosal contents of PGE2 in the fundus were not significantly different in cirrhotics with and without PHG. The gastric mucosal contents of 6-keto-PGF1 alpha significantly correlated to the plasma levels (r = 0.37, p < 0.05), but there was no significant correlation between plasma levels and gastric mucosal contents of PGE2. Since prostacyclin has vasodilator and gastric acid inhibitory effects, we speculate that high contents of prostacyclin in the gastric mucosa may have some role in the pathogenesis of PHG.

6-Ketoprostaglandin F1 alpha↗
PubMed1995

Resection of deep-seated gliomas using neuroimaging for stereotactic placement of guidance catheters.

A simple computed tomography- (CT) or magnetic resonance (MR) imaging-guided stereotactic method for guided microsurgical resection of either deep-seated gliomas or tumors adjacent to an eloquent area is described. The technique employs the Brown-Roberts-Wells stereotactic system and twist drills, 2.7 mm in diameter, for the stereotactic placement of 2.4 mm diameter scaled guidance catheters through the calvaria. In a patient with a deep-seated small glioma, less than 2 cm diameter, one catheter was implanted into the center of the enhanced mass through the cerebral cortex. In the other 14 patients, three to six catheters were used which made the tumor border clearer. After implantation of the guidance catheters, the stereotactic frame was removed and a standard open craniotomy performed. Target localization is not affected by brain movement, which is inevitable during open surgery. The tumor involved the frontal lobe in eight patients, the parietal lobe in two, and the thalamus in five. In all cases the lesion was quickly localized and radical removal was achieved. Neurological complications occurred in only one patient who suffered transient hemiparesis after the resection of a lesion in the pyramidal tract. The results demonstrate that microsurgery combined with CT- or MR imaging-guided stereotactic placement of guidance catheters is a new option for surgery of deep-seated gliomas or tumors adjacent to an eloquent area.

Adult↗
PubMed1995

192Ir induced radiation damage in monkey brain assessed with magnetic resonance imaging and histological examination.

The effects of irradiation on a large volume of normal brain tissue as occurs in interstitial brachytherapy were investigated. Double iridium-192 seed assemblies were stereotactically implanted into the right centrum semiovale of eight adult Japanese monkeys (Macaca fuscata). The morphological changes induced in the normal brain tissue were evaluated with magnetic resonance (MR) imaging with and without gadolinium-diethylenetriaminepenta-acetic acid (Gd) enhancement at 2 days and 1, 3, and 6 months after the brachytherapy. After each MR imaging examination, randomly selected experimental animals were sacrificed to analyze the histological changes. The low intensity area seen inside the ring of contrast enhancement on the T1-weighted image with Gd enhancement was well correlated with histologically defined necrosis. The high intensity area seen outside the area showing contrast enhancement on the T2-weighted image was well correlated with an area of histological edema and demyelination. The sizes of the lesion and the high intensity area were maximum during the acute stage (2 days) following interstitial irradiation. This monkey model with MR imaging can be used to investigate the development of brain damage induced by interstitial irradiation. We further recommend careful monitoring to detect the development of brain edema during the acute stage after interstitial brachytherapy, especially when large tumors are treated.

Animals↗
PubMed1995

[Image guided stereotactic biopsy for brain tumors: experience of 71 cases].

Despite advances in the neuroimaging of the brain, an accurate diagnosis of intrinsic lesion of the brain requires tissue sampling and histological verification. Seventy-one patients with intraparenchymal lesion of the brain underwent CT or MRI-directed stereotactic biopsy at Okayama University Hospital between June, 1987 and March, 1995. There were 32 men and 39 women whose ages ranged between 7 and 78 years (mean 46.1 years). All patients underwent preoperative cerebral angiography, high resolution contrast enhanced CT and MRI. The lesions were located in the hemisphere in 40 cases, the thalamus or basal ganglia in 14, the midline (corpus callosum or ventricle) in 11, the pineal region in 4, the suprasellar in one and multiple sites in one. A Brown-Roberts-Wells (BRW) CT-directed stereotactic system was used for biopsy under CT guidance. For MRI-directed biopsies a prototype modification of the BRW frame was employed. Target localization was performed using either CT or MRI. Usually one or two targets within the lesion were chosen and target coordinates were calculated using the CT or MRI scan soft ware. Positive diagnosis was obtained in 67 cases and the accuracy of the histological diagnosis was 94.4%. There were 53 gliomas, 4 metastasis, 5 germinomas, 3 malignant lymphomas, one pineoblastoma, one infarction and 4 negative biopsies. Bleeding as a complication due to stereotactic intervention occurred in one patient (1.4%). To patients with potentially inoperable lesions or lesions which might be best treated by chemotherapy or irradiation, modern techniques of neurosurgery now offer the option of precise stereotactic biopsy through small twist-drill burr holes as opposed to open biopsy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Fistula of the posterior communicating artery and cavernous sinus.

A 24-year-old man was admitted with conjunctival hyperemia of the left eye and progressive chemosis and proptosis 1 month after a head injury. An angiogram showed an arterial-cavernous sinus fistula of the posterior communicating artery, which was treated with minicoils. The atypical configuration, transvenous embolization, and unusual nature of the communication suggested that communication developed through a newly generated vessel in granulation tissue.

Adult↗
PubMed1995

Prognostic significance of hepatic vein waveform by Doppler ultrasonography in cirrhotic patients with portal hypertension.

OBJECTIVE: We prospectively evaluated the prognostic value of the flat hepatic vein waveform, measured by Doppler ultrasound, in cirrhotic patients with portal hypertension. METHODS: The Doppler pattern of right and left hepatic veins in a series of 120 consecutive cirrhotic patients with portal hypertension but without hepatocellular carcinoma was examined, together with clinical and biochemical parameters. RESULTS: Flat waveform of the right hepatic vein was recognized in nine patients and that of the left hepatic vein was seen in 13. After a mean follow-up of 13.6 +/- 9.7 months, 17 patients died, all from liver failure. In the univariate analysis, variable significantly associated with the duration of survival were age, etiology of the liver cirrhosis, upper gastrointestinal bleeding after start of the study, Child-Pugh score, ascites, encephalopathy, prothrombin index, bilirubin, albumin, and flat Doppler waveform in the right and left hepatic veins. Multivariate analysis showed that flat Doppler waveform in the right hepatic vein, bilirubin, and prothrombin index were independently related to survival. CONCLUSIONS: The prognostic accuracy in cases of cirrhosis with portal hypertension is significantly improved with acquisition of information obtained from hepatic vein waveform by Doppler ultrasound.

Adult↗
PubMed1995

Feasibility of laparoscopic cholecystectomy for patients with a nonvisualized gallbladder on drip infusion cholangiography.

We report here the operative findings, the incidence of successful laparoscopic treatment, and the perioperative complications in patients with nonvisualized gallbladder on drip infusion cholangiography (DIC). Eighty-five patients with a nonvisualized gallbladder on DIC were entered into the study. None of the patients had a minimal adhesive gallbladder; 51 to 85 patients (60.0%) had moderate adhesive gallbladders, and 34 (40.0%) had severely adhesive ones. The rate of successful laparoscopic treatment, including laparoscopy-assisted abdominal surgery, was 97.6% (83 of 85 patients). Perioperative complications occurred in only three patients (3.5%), and there were no deaths related to the operation. Thus, when patients with a nonvisualized gallbladder on DIC undergo laparoscopic cholecystectomy, meticulous procedures must be carried out; however, as the rate of successful laparoscopic treatment is high, cholecystectomy under laparoscopy is feasible for experienced surgeons.

Cholangiography↗
PubMed1995

[Continuous intraarterial infusion of 5-fluorouracil plus leucovorin for liver metastases from colorectal cancer].

Between September 1990 and August 1994, 11 patients (pts) with liver metastases (mets) from colorectal cancer were treated with continuous hepatic arterial infusion chemotherapy of 5-fluorouracil (FU) plus leucovorin (LV). Eight pts had non-resectable liver mets (H3: 7, H2: 1), and 3 had residual small mets after resection of major mets. Drugs were administered via an extracorporeal infusion device connected to the hepatic arterial infusion port. 5-FU and LV were given through a 5- to 7-day continuous infusion at 500-750 mg/body/day and 30 mg/body/day, respectively, with a 3- to 4-week rest period. In the recent 6 pts, cisplatin was administered as a 2-hour infusion at 25 mg/body, one or two times simultaneously. Grade 2 toxicity was noted in two pts (18%). One was stomatitis and another was uncontrolled ascites in an advanced cirrhotic pt. The response rate in the 9 evaluable pts was 67% with 6 PR and no CR. The duration of the response was 5 to 9 months. One- and two-year survival rates were 75% and 22%, respectively. These results were superior to those of the intermittent bolus injection of 5-FU plus MMC (or epirubicin) in 40 pts from 1977 to 1994. These results suggest that continuous 5-FU plus LV arterial infusion is an effective regimen in pts with liver metastases from colorectal cancer. However, the infusion with an extracorporeal device limits the pts' quality of life. Further investigation is needed for a schedule that can be practiced for a longer period.

Aged↗
PubMed1995

[A case of multiple liver metastasis from remnant gastric cancer responding to leucovorin.5-FU+UFT therapy].

We report a case of a 67-year-old male patient who experienced multiple liver metastasis 6 months after undergoing an operation for remnant gastric cancer. The histological classification of the cancer in gastric remnant was poorly-differentiated adenocarcinoma. The patient was treated with a low dose of LV.5-FU once a week and oral UFT as an outpatient. As a result, after 3 months of the treatment, CT showed that multiple liver lesions almost disappeared, a condition that lasted about 3 years without relapse. Toxic effects due to this treatment were temporary slight liver disfunction, mild anorexia and stomatitis. This case indicates that the regimen of LV.5-FU+UFT may be effective for multiple liver metastasis from postoperative remnant gastric cancer, enabling the patient to maintain an excellent QOL (quality of life).

Adenocarcinoma↗
PubMed1994

Liver resection for hepatocellular carcinoma in the elderly.

OBJECTIVE: To estimate the effectiveness of hepatic resection on hepatocellular carcinoma (HCC) in the elderly. DESIGN: Comparison with younger patients. SETTING: A municipal hospital and a large university hospital in Japan. PATIENTS: The study included 39 patients (age > or = 70 years [the elderly group]) and 229 patients (age < 70 years [the younger group]) who underwent hepatic resection from April 1985 to March 1993. The preoperative clinical features (Child's classification, association of cirrhosis and liver functions) were comparable between two groups. The positive rate for hepatitis C virus antibody was higher in the elderly group (88% vs 59%; P = .016). MAIN OUTCOME MEASURES: Morbidity and survival following operation and the pathological features of HCC. RESULTS: The incidence of postoperative hepatic failure was higher in the elderly group (10% vs 2%; P = .018). However, the incidence of operative death in the elderly group (5% vs 1%) as well as the incidence of other postoperative complications and rates of long-term survival (75.9% vs 51.6% at 5 years) and disease-free survival (30.4% vs 31.0% at 5 years) were similar to those in the younger group. The pathological features of HCC were identical between the two groups. CONCLUSION: The outcome of surgical treatment of HCC in the elderly group was satisfactory when compared with that in the younger group.

Age Factors↗