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Biomedical subjects

M Kitajima

Publications and source records attributed to M Kitajima.

At least 343 records · Page 19Linked to original sources
PubMed1993

Molecular cloning and characterization of a human carboxylesterase gene.

A cDNA encoding human liver carboxylesterase and its gene were isolated. Nucleotide sequence analyses of the cDNA revealed that the predicted enzyme protein consists of 567 amino acids, including 18 amino acids of a putative signal peptide. Comparison of the deduced amino acid sequences of this enzyme with those of seven other carboxylesterases in various mammalian species, together with experimental data from several other laboratories, showed that these enzymes can be classified into three groups depending on the sequences at their carboxyl terminals and the presence or absence of one exon. A human carboxylesterase gene was found to span approximately 30 kb and to have 14 small exons. Alignments of this gene with those of human cholinesterase and rat cholesterol esterase indicated insertional sites at some introns and homologous amino acid sequences around them, although these genes have different numbers of exons. Thus the results supported the conclusion that these esterases evolved from a common ancestral gene.

Amino Acid Sequence↗
PubMed1993

Analysis of a genetic mutation in an electrophoretic variant of the human lactate dehydrogenase-B(H) subunit.

An electrophoretic variant of the lactate dehydrogenase (LDH)-B(H) subunit was discovered in a patient with diabetes mellitus. His LDH activity in serum was slightly lower than normal and the LDH isozyme pattern showed an abnormal migration indicating an LDH-B subunit variant of the fast type. The LDH containing the variant subunit revealed a decreased heat stability. DNA analysis of the variant allele detected a base substitution, an A to G transition, at codon 6 (AAA-->GAA). The mutation resulted in the replacement of a lysine by a glutamic acid (K6E). The change may cause the heat instability and affect the net charge of the variant subunit, resulting in an electrophoretic LDH-B subunit variant of the fast type.

Aged↗
PubMed1993

Detection and characterization of new genetic mutations in individuals heterozygous for lactate dehydrogenase-B(H) deficiency using DNA conformation polymorphism analysis and silver staining.

Human lactate dehydrogenase (LDH)--B(H) mutant genes were analyzed by polymerase chain reaction (PCR) and DNA conformation polymorphism. We used polyacrylamide gradient gel and silver staining procedures for DCP analysis, and observed abnormal migration patterns in individuals heterozygous for the LDH-B deficiency. Subsequent sequence determination of the mutant alleles consistently resulted in detection of three single base substitutions (transversions), viz., a C to A at residue "35" (GCG, Ala-->GAG, Glu), a T to G at residue "172" (TTT, Phe-->GTT, Val), and an A to T at residue "176" (ATG, Met-->TTG, Leu). Furthermore, mismatched PCR or amplification refractory mutation system was developed for the rapid screening and confirmation of these mutations. These amino acid replacements may cause conformational changes in neighboring residues; this probably affects the active site arrangement and results in the loss of enzyme activity.

Amino Acid Sequence↗
PubMed1993

Synergetic effect of interleukin-2 and cellular cytotoxicity against a novel tumor-associated carbohydrate antigen Le(a)/Le(a) (dimeric Le(a)) mediated by monoclonal antibody NCC-ST-421 in adoptive immunization using SCID mice.

The murine IgG3 monoclonal antibody NCC-ST-421, raised against a human gastric cancer, shows strong reactivity with dimeric Le(a) (Le(a)/Le(a); V4FucIII4FucLc6Cer) expressed on gastrointestinal cancer cells. ST-421 reacted minimally with non-dimeric or simple Le(a) expressed on normal tissues. ST-421 is capable of mediating both antibody-dependent cellular cytotoxicity (ADCC) with human peripheral blood lymphocytes, and complement-dependent cytotoxicity with human complement. Interleukin-2 (IL-2) modulates the function of immunocytes, in particular inducing lymphokine-activated killer (LAK) cell activity and enhancing ADCC. We therefore employed combination immunotherapy with IL-2, LAK, and ST-421-induced ADCC in vitro and in mice with severe combined immunodeficiency (SCID), using target tumor cells expressing Le(a)/Le(a) antigen. ADCC against human colon cancer cell lines in vitro was enhanced three to four times after preincubation with IL-2. Addition of IL-2 reduced the amount of ST-421 required for efficient ADCC 10- to 100-fold. ADCC was activated by IL-2 earlier (1 day) than the generation of LAK cells (3-4 days), and at lower concentration of IL-2. These effects were specific for ST-421, as demonstrated by experiments with irrelevant antibody or irrelevant target cells. An anti-(Fc receptor) antibody blocked the ADCC but not the LAK activity in vitro. The enhancement of ADCC by IL-2 may be caused by activation of effector cells expressing Fc receptors. In vivo experiments using SCID mice inoculated with human colon cancer showed a significant tumor-growth-suppressive effect after combined therapy using human peripheral blood lymphocytes, LAK, IL-2, and ST-421. In summary, adoptive immunization with human lymphocytes activated by IL-2 and ST-421 effectively suppressed growth of gastrointestinal cancer cells expressing Le(a)/Le(a).

Animals↗
PubMed1993

Alteration in proliferative and endocrine responsiveness of human mammary carcinoma cells by prototypic tumor-suppressing agents.

The experiments performed in this study were designed to establish that (1) acquisition of anchorage-independent growth, a biological characteristic of tumorigenically transformed phenotype, can be modulated by prototypic tumor-suppressing agents, and (2) modulation of growth is influenced by the metabolic competence of the cells to biotransform estradiol, MCF-7 human breast carcinoma cells exhibited linear cell proliferative kinetics with a 41-hour population doubling time, and a 15% colony-forming efficiency in 0.33% agar. Indole-3-carbinol (13C), a naturally occurring tumor-suppressive agent; tamoxifen (TAM), an antiestrogenic agent; and 4-hydroxytamoxifen (4-OHTAM), a metabolite of TAM, demonstrated 73.7%, 72.5%, and 89.9% suppression in anchorage-independent growth of MCF-7 cells, respectively. At the metabolic level, 13C and 4-OHTAM induced 2.3-fold (P < 0.0001) and 1.3-fold increase (P = 0.001) relative to their own controls in the extent of 2-hydroxylation of estradiol. The results indicate that growth inhibition by 13C, TAM, and 4-OHTAM may in part be due to altered estradiol metabolism in MCF-7 cells. Thus, anchorage-independent growth and altered biotransformation of estradiol may constitute useful cellular and endocrine markers to evaluate the biological response of chemosuppressive agents.

Antineoplastic Agents↗
PubMed1993

Increased chemiluminescence and ulcer development in the low blood flow state of the gastric tube for esophageal replacement.

Peptic ulcers in the gastric tube for esophageal replacement develop in spite of reduction of acid secretion after truncal vagotomy and often result in serious conditions such as bleeding and perforation. Thirteen cases of gastric tube ulcers were detected endoscopically from 1985 to 1990 in our hospital. Most of these ulcers developed within 20 cm of the anastomosis (esophagogastrostomy), which was an especially hypoxic and ischemic area. Ischemic change due to decreased blood supply is suggested as a causative factor in ulcer development. Recent studies indicate that chemiluminescence (ChL) activity may increase even in the low-flow hypoxic condition. Therefore, we investigated the ChL of regional blood in the hypoxic gastric tube in dogs. The ChL activity of the blood sample collected from the ischemic region in the gastric tube significantly increased after construction of the gastric tube, compared with systemic blood from the femoral vein, and the number of leukocytes decreased in the ischemic region. We believe that oxygen radicals derived from neutrophils adhering to the vascular endothelium may play an important role in the damage to endothelial cells of the gastric tube and suggest the possibility of their causative effects in the process of ulcer formations.

Anastomosis, Surgical↗
PubMed1993

Enhancement of antitumor activity of cisplatin on human gastric cancer cells in vitro and in vivo by buthionine sulfoximine.

An attempt was made to evaluate the enhancement of the antitumor activity of cisplatin (DDP) by buthionine sulfoximine (BSO) in vitro and in vivo. In the in vitro study, pre-treatment with BSO (5, 10 and 25 mM) increased the antitumor activity of DDP against the gastric cancer cell lines MKN-28 and MKN-45, whereas BSO alone exhibited only slight antitumor activity (inhibition rate, 20-30%). In the in vivo study, the antitumor effects of DDP against human gastric cancer xenografts St-15 and SC-1-NU in BALB/c nu/nu mice were enhanced pretreatment with BSO, which was administered intraperitoneally at a dose of 500 mg/kg according to a schedule of qd x 3. BSO alone showed no antitumor effects against these tumors in nude mice. The side effects (assessed in terms of death rate and body weight loss) associated with the maximum tolerated dose of DDP (9 mg/kg) were not increased by BSO pretreatment. As BSO increased the antitumor activity of DDP without a corresponding increment of its toxicity, BSO appears to be a promising agent for further study.

Animals↗
PubMed1993

Revaluation of endoscopic laser therapy for treatment of early cancer in the stomach.

The efficacy and safety of the endoscopic laser therapy for eradication of early cancer in the stomach was revaluated in fourty-eight patients. In 37 of the 42 patients (88%) treated with the laser therapy alone, the procedure was effective and the complete eradication was confirmed at the end of the follow-up period. In seven of fourteen patients with the incomplete treatment, residual cancer cells were successfully removed by repeated laser therapy. The endoscopic mucosal resection was effective in 21 of the 30 patients (70%) with the early gastric cancer. Interestingly, six of the eleven cases with incomplete treatment with the endoscopic mucosal resection underwent the laser therapy and the complete eradication was achieved in all patients. Although the endoscopic mucosal resection is now the main method for the endoscopic treatment of the early gastric cancer, these data favor offering the endoscopic laser therapy as the combined method with the mucosal resection therapy.

Adult↗
PubMed1993

Carbohydrate antigens and liver metastasis in colorectal cancer.

A comparative immunohistochemical study was performed to analyse the expression of cancer-associated carbohydrate antigens by primary and metastatic lesions of colon cancer. We used monoclonal antibodies which reacted with Lea, Lex and Tn as well as their sialylated derivatives. Twenty-one primary lesions in patients without metastasis and 26 primary and metastatic lesions in patients with liver metastasis were studied. Sialyl Lea was expressed by 57% of the primary lesions of patients without metastasis, 65% of the primary lesions of patients with metastasis and 73% of their liver metastases. Sialyl Lex was expressed by 60% of the primary lesions of patients with and without metastasis as well as by approximately 80% of the liver metastases. Sialyl Lea and sialyl Lex showed strong expressions in the liver metastases, significantly greater than in the primary lesions. The findings indicate the increased expressions of sialyl Lea and sialyl Lex to be correlated with liver metastasis of colorectal cancer.

Adenocarcinoma↗
PubMed1993

Anastomotic leakage after colorectal cancer surgery: a risk factor for recurrence and poor prognosis.

In order to discover the incidence of recurrence and prognosis of patients with anastomotic leakage after colorectal surgery, 980 colorectal cancer patients who underwent anastomosis at Keio University Hospital between 1970 and 1990 were examined. Thirty-three patients (leakage group) out of the 980 exhibited anastomotic leakage. The incidence of local recurrence in the leakage group was significantly higher than in the no leakage group (P < 0.01). The disease-free survival rate of the leakage group was significantly lower than that of the no leakage group in Dukes' A, B patients (P < 0.01), but was not so in Dukes' C, D patients. These results suggested that anastomotic leakage after colorectal cancer surgery might enhance the incidence of local recurrence and make the prognosis poor.

Aged↗
PubMed1993

Splenic abscess associated with colon cancer: a case report.

The present report describes a case of colon cancer which presented with a rare complication of splenic abscess. A 52-year-old Japanese man with diarrhea, fever and chills was admitted to our hospital. He complained of fever, with chills at night, and abdominal pain occurring during the last month. The origin of the fever was investigated, and Escherichia coli grew from a blood culture. Multilocular splenic abscesses and wall thickening of the descending colon were revealed by CT scan, magnetic resonance imaging and ultrasound. A cancer of the descending colon was found by barium enema and colonoscopy. A curative resection was performed and the pathological report revealed the splenic abscess to have developed from a direct extension of, and perforation by, the carcinoma of the descending colon.

Abscess↗
PubMed1993

[Targeting therapy using monoclonal antibody directed against growth factor receptors].

Targeting therapy is expected to be a new effective anti-cancer treatment in near future. Major advances are achieved by considerable effort in this area. Monoclonal antibodies that recognize tumour-associated antigens were conjugated to chemotherapeutic drugs, toxins and radionuclides with various procedures. To apply this new therapy for clinical use, many problems still remain to be clarified. These problems consist of human anti-mouse antibody, antigenic heterogeneity and low tumour uptake. By our experiment, growth factor receptor was an ideal target for targeting therapy and immunoconjugate directed against growth factor receptor showed selective cytotoxicity to cancer cells with expression of growth factor receptor. Moreover, cytotoxic effect was positively correlated with expression level of growth factor receptor.

Animals↗
PubMed1993

[High clinical predictability of histoculture drug response assay (HDRA) for drug-sensitivity of cancer of the digestive organs].

Fresh surgical specimens from 250 patients with cancer were used for the histoculture drug response assay (HDRA) with MTT method. Scissor cut small pieces of the specimens were placed onto collagen-gel-matrix which was incubated in 24 well-plate dishes filled with medium containing mitomycin C (MMC), adriamycin (ADM), 5-fluorouracil (5-FU) or cisplatin (CDDP). The cutoff concentrations of the drugs used are 7.5 micrograms/ml for MMC, 15 micrograms/ml for ADM, 300 micrograms/ml for 5-FU and 20 micrograms/ml for CDDP. After 7 days incubation, the specimens were assessed the inability to reduce MTT. A 50% or greater inhibition of MTT reduction at the cutoff concentrations indicated in vitro sensitivity. The clinical effect of the drugs was evaluated according to the criteria of the Japanese Society for Cancer Therapy. Two hundred thirty two (93%) cases were evaluable, and in vitro and in vivo correlation was compared in 42 cases. Of the 33 patients whose tumors showed drug resistance in HDRA, 33 failed treatment with one or more of these agents. Of the nine patients whose tumors showed drug sensitivity in HDRA, six had chemo-responses (2 CRs and 4 PRs) for a total accuracy of 93% (34/42). The advantages of HDRA include, three-dimensional tumor cell growth in in vitro culture with cell to cell contact and maintenance of tissue architecture, 7 days to assess the effect of antitumor agents, ability to evaluate both growing and resting tumor cells, small amounts of specimen required for assay, and high evaluable and predictable rates for clinical use in designing optimal chemotherapy regimens for cancer patients.

Cisplatin↗
PubMed1992

High in vitro-in vivo correlation of drug response using sponge-gel-supported three-dimensional histoculture and the MTT end point.

The in vitro sponge-gel-supported three-dimensional histoculture chemosensitivity assay (Hoffman assay) allows the in vivo-like culture of human tumors. In this study, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H tetrazolium bromide (MTT) end point was applied to the Hoffman assay in an attempt to increase in vitro-in vivo correlation. The chemosensitivities of 16 human tumor lines were determined in vitro by the histoculture assay, and retrospectively correlated to their in vivo chemosensitivity as xenografts in nude mice. The in vitro test was considered to be positive if tumor-cell MTT reduction activity was lowered by more than 50%. The cutoff drug concentrations to determine sensitivity in vitro were determined for mitomycin C, doxorubicin, 5-fluorouracil and cisplatin. Using these cutoff drug concentrations in vitro we found, as a function of time of exposure, a strong correlation between serum drug concentrations found in nude mice given maximum tolerated doses and drug concentrations found in the histoculture media in vitro, thereby establishing a relationship between the amounts of drugs to which tumors were exposed in vivo and in vitro. The overall correlation rate of the efficacy results of the drug-response assay to in vivo chemosensitivities was 89.8%, with 90.0% true-positive and 89.7% true-negative rates, 81.7% sensitivity and 94.6% specificity, thereby indicating potential clinical use for tumor histoculture with the MTT end point.

Animals↗