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Biomedical subjects

K Sugano

Publications and source records attributed to K Sugano.

At least 19 recordsLinked to original sources
PubMed1995

Structural and functional analysis of the canine histamine H2 receptor by site-directed mutagenesis: N-glycosylation is not vital for its action.

G-protein-coupled receptors generally share a similar structure containing seven membrane-spanning domains and extracellular site(s) for N-glycosylation. The histamine H2 receptor is a member of the family of G-protein-coupled receptors, and has three extracellular potential sites for N-glycosylation (Asn-4, Asn-162 and Asn-168). To date, however, no information has been presented regarding N-glycosylation of the H2 receptor. To investigate the presence, location and functional roles of N-glycosylation of the H2 receptor, site-directed mutagenesis was performed to eliminate the potential site(s) for N-glycosylation singly and collectively. The wild-type and mutated H2 receptors were expressed stably in Chinese hamster ovary (CHO) cells or transiently in COS7 cells. Immunoblotting of the wild-type and mutated H2 receptors with an antiserum directed against the C-terminus of the H2 receptor showed that mutation at Asn-162, but not at Asn-168, resulted in a substantial decrease in the molecular mass. A mutation at Asn-4 led to a further decrease in the molecular mass. Tunicamycin treatment of the transfected cells yielded a sharp band with a molecular mass identical to that of the mutant devoid of all three potential sites for N-glycosylation. These findings indicate that the H2 receptor is N-glycosylated, and that N-glycosylation takes place mainly at two sites, Asn-4 and Asn-162. Neither the affinity for tiotidine nor that for histamine was affected by the mutagenesis. Immunocytochemistry and tiotidine binding showed that the mutated receptors were exclusively distributed on the cell surface in a fashion similar to that of the wild-type. In addition, the glycosylation-defective receptor was capable of activating adenylate cyclase and elevating the intracellular Ca2+ concentration in response to histamine in stable CHO cell lines. Thus N-glycosylation of the H2 receptor is not required for cell surface localization, ligand binding or functional coupling to G-protein(s).

1-Methyl-3-isobutylxanthine↗
PubMed1995

Single-strand conformation polymorphism analysis by perpendicular temperature-gradient gel electrophoresis.

Using a newly developed temperature-gradient gel electrophoresis apparatus, mutations in the K-ras oncogene and p53 tumor suppressor gene were analyzed for single-strand conformation polymorphism (SSCP). The mobilities of single-stranded DNAs, carrying various mutations, change--depending on the gel temperature during electrophoresis. Therefore, temperature-gradient single-strand conformation polymorphism (TG-SSCP) analysis can provide useful information concerning the optimum temperature for SSCP and may also be used to screen for various mutations or polymorphisms in a single electrophoretic run.

Base Sequence↗
PubMed1995

[A 56-year-old woman with parkinsonism and dementia with the age of onset at 41 years].

We report a 56-year-old woman with parkinsonism and dementia who died of respiratory failure. The patient was well until the age of 41 when she noted insidious onset of difficulty in moving around. Soon after, she noted tremor in both her hands and gait disturbance. She received stereotaxic right thalamotomy when she was 46-year-old; after thalamotomy, improvement was noted in her tremor, rigidity, and in gait. However, a few months later, she started to experience motor fluctuations with worsening of her symptoms in the afternoon. This worsening was temporarily relieved by increasing her levodopa/benserazide dose. She started to show visual hallucination and agitation when she was 54-year-old. Her symptoms had progressively become worse with marked motor fluctuations and she was admitted to our hospital when she was 56-year-old. On admission, she was alert and general physical examination was unremarkable. Neurologic examination revealed that she was disoriented to time and place; memory was markedly disturbed and calculation was poor. Hasegawa dementia scale was 7/30. Higher cerebral functions appeared intact. She showed masked face, small voice, and some dysphagia. Other cranial nerves were intact including ocular movements. She was unable to walk by herself; when supported she walked in small steps with marked disturbance in the righting reflex. Mixed rigidity and Gegenhalten was noted in her four limbs and in the neck. Tremor was absent. She showed marked akinesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Age of Onset↗
PubMed1995

[Early phase II trial of l-leucovorin and 5-fluorouracil in advanced colorectal cancer. l-Leucovorin and 5-FU Study Group].

We report the results of a multicenter clinical trial comparing three combination chemotherapeutic regimens including 5-fluorouracil (5-FU) and l-leucovorin (l-LV). One hundred and twenty-two patients were randomized to three regimens comprising 5-FU (600 mg/m2) plus high-dose l-LV (250 mg/m2) in six doses given weekly by i.v. injection midway during a 2-hr infusion of l-LV (regimen A), 5-FU (370 mg/m2) plus high-dose l-LV (100 mg/m2) given simultaneously for 5 consecutive days and a 23-day interval between treatments (regimen B) and 5-FU (370 mg/m2) plus low-dose l-LV (10 mg/m2) with the same dose administration schedule as regimen B (regimen C). The response rates were 32.4% (12/37 cases) in Regimen A, 20.0% (8/40) in regimen B and 11.1% (4/36) in regimen C. The most prominent side effects observed in regimen A were diarrhea (53.8%) and leukopenia (53.8%); however, they were within permissible levels. The combinations of high-dose l-LV and 5-FU (regimen A and B) had higher response rates than that of low dose l-LV and 5-FU (regimen C). Weekly administration of high-dose l-LV and 5-FU (regimen A) is now being expanded to late phase II trials.

Aged↗
PubMed1995

Clinical trial of continuous infusion of 5-fluorouracil using an ambulatory pump for metastatic colorectal cancer.

A clinical trial was conducted in order to evaluate the anti-tumor effect and toxicity of a continuous infusion of 5-fluorouracil (5-FU) for metastatic colorectal cancer. Two-hundred and fifty mg/m2/day 5-FU was administered as a continuous infusion through an indwelling central venous catheter with ambulatory pump. Twenty patients with metastatic colorectal cancer which could be measured or evaluated were enrolled in the trial. The objective response rate was 35% (95% confidence interval, 14-56%). The response rates by site were 33% in liver, 17% in lung, 60% in lymph nodes, 50% in adrenal gland and 50% in primary lesion. The major toxicity was stomatitis (50%; grades 2 and 3 on Eastern Cooperative Oncology Group (ECOG) criteria) and hand-foot syndrome (40%; grades 2 and 3 on ECOG criteria). The sequence of toxicity was stomatitis first, followed by hand-foot syndrome. The median cumulative dose of 5-FU from the initiation of therapy to the onset of toxicity was 7125 mg in stomatitis and 17,875 mg in hand-foot syndrome. These toxicities were mild and reversible after a short interruption to the 5-FU infusion. Neither hematological toxicity nor serious catheter-related complications were observed. We concluded that continuous infusion of 5-FU was a feasible treatment for the patient with metastatic colorectal cancer, and manageable on an out-patient basis.

Adult↗
PubMed1995

[Late phase II trial of high-dose l-leucovorin and 5-fluorouracil in advanced colorectal carcinoma. l-Leucovorin and 5-FU Study Group (Japan Eastern Group)].

A multicenter cooperative study was conducted from Dec. 1992 to April 1994 to evaluate the clinical efficacy of high-dose l-leucovorin (l-LV) and 5-fluorouracil (5-FU) treatment in 76 patients with advanced colorectal carcinoma. Treatment consisted of intravenous bolus injection of 5-FU (600 mg/m2) 1-hour after the initiation of a 2-hour infusion l-LV (250 mg/m2), 6 weekly treatments were administered followed by a two-week rest. These treatment were repeated until progressive disease or intolerable toxicity. Seventy patients were evaluated for response. Responses were the following: PR 21, NC 29, PD 20 and the overall response rate was 30%. Grade 4 hematological side-effect was observed in three cases, and severe diarrhea in one case. These data suggested that high-dose l-LV and 5-FU was effective for advanced colorectal carcinoma but showed some hematological toxicity, and a further investigation should be carried out.

Aged↗
PubMed1994

Detection of point mutations in the K-ras oncogene at codon 12 in pure pancreatic juice for diagnosis of pancreatic carcinoma.

BACKGROUND: Mutations in the K-ras oncogene at codon 12 are detected at a remarkably high frequency in pancreatic carcinomas and are believed to be a critical event in oncogenesis. The authors attempted to detect K-ras mutations in DNA obtained from pure pancreatic juice collected endoscopically, as a novel diagnostic approach to pancreatic carcinoma. METHODS: K-ras mutations were examined using the two-step polymerase chain reaction (PCR) combined with restriction enzyme digestion, followed by nonradioisotopic single-strand conformation polymorphism (SSCP) analysis. RESULTS: Specific mutations of the K-ras gene at codon 12 were found in six of nine (67%) duct cell carcinomas, all of which were negative by cytodiagnosis of the same pure pancreatic juice. K-ras mutations were not detected in the pancreatic juice from 14 healthy control subjects, 10 patients with chronic pancreatitis, or 3 patients with islet cell tumors. CONCLUSIONS: Detection of K-ras mutation at codon 12 in pancreatic juice is highly specific for diagnosing pancreatic duct cell carcinoma and may be a valuable diagnostic modality for pancreatic carcinoma and for differentiating chronic pancreatitis from carcinoma.

Adenocarcinoma↗
PubMed1994

Production of bioactive gastrin from the non-endocrine cell lines CHO and COS-7.

We made a mutated progastrin cDNA construct that contains a cleavage site (-Arg(-4)-Arg(-3)-Lys(-2)-Arg-1) specific for the Kex2-like endoprotease furin, located ahead of the bioactive gastrin. For expressing the mutated progastrin cDNA, we used two non-endocrine cell lines, CHO and COS-7. CHO cells exhibit amidating enzyme activity and levels of amidation enzyme mRNA as high as those in the pituitary-derived endocrine cell line GH3, whereas COS-7 cells have far less amidating activity and lower amounts of mRNA. Mutant progastrin-expressing CHO cells produced mostly amidated gastrin. Gel filtration showed the size of this gastrin corresponded to that of the synthetic human gastrin-17. In contrast, COS-7 cells produced glycine-extended gastrin and only a small amount of amidated gastrin. The difference in the amount of amidated gastrin products produced by the two non-endocrine cell lines is due to differing amounts of the amidation enzyme contained in each cell line.

Amino Acid Sequence↗
PubMed1994

Pancreatic carcinoma accompanied by pseudocyst: report of two cases.

Two cases of pancreatic cancer accompanied by pseudocyst are reported. Case 1 was a 60-year-old man who was admitted to our hospital complaining of left lower abdominal discomfort. A cystic lesion, about 3 cm in diameter, was found in the pancreatic tail by ultrasonography (US) and computed tomography (CT). No signs of chronic pancreatitis were found. At operation, an elastic, hard, white tumor, about 1 cm in diameter, was felt adjacent to the cystic lesion on the duodenal side. Histologically, this tumor was a duct cell carcinoma with an adjacent pseudocyst upstream of the pancreas. Case 2 was a 57-year-old man who complained of back pain and loss of body weight. US and CT examination revealed a cystic lesion, 11 x 7 cm in size, in the tail of the pancreas. Histological examination of the resected specimen revealed both a duct cell carcinoma, 3 cm in size, in the body of the pancreas and a pseudocyst, 9 cm in size. Pseudocysts accompanying carcinoma are thought to develop from obstruction of the pancreatic duct by the carcinoma, followed by intraductal high pressure and disruption of ductules upstream of the pancreas. Thus, we should pay careful attention to pseudocyst of the pancreas, especially when signs of diffuse chronic inflammation cannot be found, to help identify duct cell carcinoma in the early stage. Further detailed examinations of the cyst fluid or pancreatic juice, such as cytology, tumor marker determinations, or establishment of K-ras codon 12 mutation, are needed.

Carcinoma, Ductal, Breast↗
PubMed1994

Salty food intake and risk of Helicobacter pylori infection.

To clarify the risk factors for Helicobacter pylori infection, which is considered to play an etiologic role in atrophic gastritis, duodenal ulcer and gastric cancer, various parameters including diet and socioeconomic characteristics were compared between H. pylori-infected and non-infected men. In a cross-sectional study of 634 men aged 40 to 49 years selected randomly from five areas with different rates of gastric cancer mortality, 474 of 628 men evaluated were positive for IgG antibody against H. pylori. After logistic regression analysis adjusted for area, the results showed a significant association between frequent intake of pickled vegetables and prevalence of H. pylori antibody (odds ratios against men who consume < 1 day/week 1.19 for 1-2 days/week, 1.92 for 3-4 days/week, 1.90 for 5-7 days/week; P for trend = 0.02). Daily consumption of miso soup was also associated with an increased risk (odds ratio against non-daily consumer = 1.60, 95% confidence interval = 1.03-2.49). Occupation, number of siblings, education, smoking and alcohol drinking, and other dietary habits were not significantly associated with the prevalence of infection in this population. Although there are limitations in a cross-sectional study such as this, consumption of salty foods appears to increase the risk of H. pylori infection, which could be a marker of salty food intake or an intermediate risk factor in the etiologic sequence between salty food intake and gastric cancer.

Adult↗
PubMed1994

Detection of novel mutations in the gyrA gene of Staphylococcus aureus by nonradioisotopic single-strand conformation polymorphism analysis and direct DNA sequencing.

A total of 36 clinical isolates of Staphylococcus aureus (29 fluoroquinolone-resistant strains and 7 fluoroquinolone-susceptible strains) were studied for the presence of point mutations in the gyrA gene by nonradioisotopic single-strand conformation polymorphism (Non-RI SSCP) analysis with silver stain. Direct DNA sequencing analysis of the PCR-amplified DNA fragments confirmed the results obtained by Non-RI SSCP analysis and revealed that fluoroquinolone resistance is closely associated with six types of mutations in the gyrA gene, of which three types of mutations were newly identified: (i) Ser-84-->Leu and Glu-88-->Gly, (ii) Ser-84-->Leu and Glu-88-->Lys, and (iii) Glu-88-->Gly. Furthermore, the novel ATT-->ATC mutation at codon 86 (silent mutation) was seen in only one fluoroquinolone-susceptible strain. All seven mutational types were separated from the wild type in a single electrophoretic step within 3 h after PCR amplification. Thus, we conclude that this new technique is a rapid, simple, and useful screening method for the genotyping of gyrA mutations associated with fluoroquinolone resistance.

Base Sequence↗
PubMed1994

Comparison of c-erbB-2 oncoprotein expression in tissue and serum of patients with stomach cancer.

Resected specimens of 288 primary stomach cancers (175 early cases and 113 advanced cases) and recurrent tumors or biopsy specimens of 21 recurrent or inoperable metastatic stomach cancers were examined immunohistochemically for expression of c-erbB-2 oncogene product. c-erbB-2 protein-positive staining was detected in 6.9, 15.9 and 28.6% of early, advanced and recurrent or inoperable metastatic stomach cancers, respectively, the difference being significant (p < 0.005). Four patients with advanced cancer showed positive staining in metastatic lymph nodes but not in the primary tumors. The results of tissue immunostaining were compared with c-erbB-2 protein levels in sera of the patients measured by an enzyme-linked immunosorbent assay. The levels of this oncogene product were consistently low in the sera of most of the patients with primary stomach cancers, regardless of whether or not c-erbB-2 protein was expressed in the tumor. However, in the recurrent or inoperable metastatic stomach cancers, 5 of 6 patients with c-erbB-2 protein-positive tumors showed elevated levels of c-erbB-2 protein in the serum. After following up c-erbB-2 protein levels in the sera of 3 patients during the period of chemotherapy against recurrent or inoperable metastatic disease, we found that the levels increased only in the late stage. These results suggest that, in stomach cancer, c-erbB-2 protein is likely to be excreted into the serum at a relatively late stage, reflecting systemic spread of the disease.

Adenocarcinoma↗
PubMed1994

[Clinical study of serum ErbB-2 protein using sandwich radioimmunometric assay (ErbB-2 IRMA 'Eiken')].

Sandwich radioimmunometric assay (ErbB-2 IRMA 'Eiken') was developed to determine the levels of c-erbB-2 oncogene product (ErbB-2 protein) in human sera, and a clinical investigation was carried out to evaluate this novel oncogene product. The mean serum concentration of the ErbB-2 protein determined from 364 donors was 4.0 +/- 0.69 ng/ml (mean +/- SD) for females and 4.5 +/- 0.96 ng/ml for males. Cut-off values were set at 5.4 ng/ml for females and 6.5 ng/ml for males. The positivities of serum ErbB-2 protein in patients with breast carcinoma were 13.0% for primary cases and 47.9% for recurrent cases. Patients with hepatic disorders also had positive serum ErbB-2 protein levels, ie, 43.8% (7/16) for hepatocellular carcinoma and 28.9% (11/38) for hepatitis and liver cirrhosis, although the increase was slight and barely exceeded 10 ng/ml. In comparison with the levels of other tumor markers, such as CEA, CA 15-3 and NCC-ST 439, the serum ErbB-2 level was shown to have poor correlations, and was thus assumed to be useful for combination with those tumor markers. In serial determinations of serum ErbB-2 protein in two patients with recurrent breast carcinoma, the antigen increased preceding the increases in the other tumor markers, thereby also showing usefulness as a monitoring marker for breast carcinoma. In conclusion, these results indicated that ErbB-2 measurement improves the assessment of breast cancer in combination with other tumor markers and is useful as a tool for monitoring the clinical condition and the response for treatment in breast cancer.

Aged↗
PubMed1994

[Clinical evaluation of serum ErbB-2 protein using enzyme immuno assay (ErbB-2 EIA [Nichirei])].

The levels of ErbB-2 protein in serum samples from patients with breast cancer, other various malignant tumors, and benign diseases were determined using the sandwich EIA for clinical evaluation. In 364 healthy blood donors, cut-off values were set at 5.4 ng/ml for females and 6.5 ng/ml for males. The positive rate of primary breast cancer was 13.0% (24/185) and that of recurrent breast cancer was 51.2% (62/121). No significant correlation was found between serum levels of ErbB-2 protein and other tumor markers, such as CEA, CA 15-3, and ST 439. Measurement of ErbB-2 protein in combination with these tumor markers showed increased sensitivities. The positive rates and levels of ErbB-2 protein in sera of patients with metastasis to multiple organs were significantly higher than those in patients with metastasis to only a single organ. In postoperative follow-up of two patients with recurrent breast cancer, the levels of ErbB-2 exceeded its cut-off value a few months earlier than did the other tumor markers. These results indicate that the measurement of the ErbB-2 protein in serum is useful for the diagnosis and a monitoring the relapse of breast carcinoma.

Biomarkers, Tumor↗
PubMed1994

[Clinical evaluation of ErbB-2 protein in tissue extract using an enzyme immuno assay (ErbB-2 EIA "Nichirei")].

ErB-2 protein levels in breast cancer tissue extracts were determined by an enzyme immuno assay (ErbB-2 EIA "Nichirei") using anti-c-erbB-2 monoclonal antibodies, and compared with the c-erbB-2 gene amplification detected by dot blot hybridization or differential PCR, and with the overexpression detected by immunostaining. The positivities of c-erbB-2 gene amplification and overexpression in breast cancer tissues were 25.0% (14/56) and 39.3% (46/117), respectively. The cut-off values of the Erb B-2 protein in tissue extract by EIA were set at 18.0 ng/mg-protein for gene amplification and 10.4 ng/mg-protein for overexpression, respectively, from the data of breast cancer tissues which were negative for c-erbB-2 gene. The accuracy of the ErbB-2 protein levels in tissue extract with c-erbB-2 gene amplification and overexpression were 90.6% and 79.2% using these cut-off values respectively. The result of c-erbB-2 gene amplification, overexpression, and ErbB-2 protein levels were significantly correlated with negative estrogen receptor (ER) and progesterone receptor (PgR) status in tissue cytosol fraction. These results indicate that measurement of ErbB-2 protein in tissue extract is useful to estimate the c-erbB-2 gene amplification and/or overexpression in breast cancer tissues.

Antibodies, Monoclonal↗
PubMed1994

Expression of histamine H2 receptor in Chinese hamster ovary cells: a probe to study the desensitization mechanism.

Canine histamine H2 receptor DNA, cloned by polymenase chain reaction (PCR), was transfected into Chinese hamster ovary cells using an expression vector. The expression of H2 receptors was demonstrated by immunoblotting with specific antibodies and the binding of tiotidine, an H2 receptor antagonist. H2 receptor-specific cAMP production was observed only in cells expressing canine H2 receptors. Preincubation of transfected cells with 10 microM histamine for 10 or 60 min at 37 degrees C decreased both the maximal response and the sensitivity of the subsequent histamine-stimulated cAMP production, showing desensitization. Under these circumstances, decreases in tiotidine binding without changes in affinity in intact cells and also in the membrane were observed, whereas there was no decrease in total H2 receptor number. Thus, desensitization of histamine H2 receptor was associated with the sequetration of receptors.

Animals↗
PubMed1993

Desensitization of canine histamine H2 receptor expressed in Chinese hamster ovary cells.

Canine histamine H2 receptor DNA was transfected into Chinese hamster ovary cells using an expression vector. Expression of H2 receptors was demonstrated by immunoblotting with specific antibodies and the binding of tiotidine, an H2 receptor antagonist. H2 receptor-specific cAMP production was observed only in the cells expressing canine H2 receptor with 10(-9)-10(-4) M histamine in a dose-dependent manner. Preincubation of transfected cells with 10 microM histamine for 10 min or 60 min at 37 degrees C decreased both the maximal response and the sensitivity of the subsequent histamine-stimulated cAMP production, showing desensitization. Under these circumstances, tiotidine binding was decreased by 25% in intact cells. A similar decrease in the tiotidine binding was observed also in the membrane without changes in the affinity, whereas no decrease in total H2 receptor number was observed. Thus, desensitization of histamine H2 receptor was associated with the sequestration of receptors.

Adenylyl Cyclases↗