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Biomedical subjects

K Akagi

Publications and source records attributed to K Akagi.

At least 91 records · Page 5Linked to original sources

Molecular cloning and characterization of mouse HS1.

Here we report the cloning of a cDNA and a genomic DNA encoding the mouse homolog of human HS1, a hematopoietic cell-specific protein-substrate of non-receptor type protein-tyrosine kinase(s). Sequence analysis of the mouse HS1 cDNA revealed that it is highly homologous to human HS1 (total percent match = 84%) especially in the amino-terminal half, which contains unique repeating motifs, and in the carboxyl-terminal Src-homology 3 domain. As is the human counterpart, the mouse HS1 gene is expressed exclusively in hematopoietic cells. Genomic fragments covering most of the HS1 gene were isolated and used to map this gene to mouse chromosome 16.

Adaptor Proteins, Signal Transducing↗

Deletion mapping of the long arm of chromosome 22 in human meningiomas.

Cytogenetic and molecular genetic analyses have shown that a tumor-suppressor gene for human meningioma is located on the long arm of chromosome 22. Recently, somatic mutations of the NF2 gene have been identified in sporadic meningiomas. However, tumorigenesis of certain cases of meningioma cannot be fully explained by inactivation of the NF2 gene alone. Thus, to obtain some indication as to the existence of another tumor-suppressor gene, it seemed important to re-examine the loss of heterozygosity (LOH) on 22q in sporadic meningioma. A total of 46 sporadic meningiomas was examined for LOH at 20 loci on 22q. LOH was observed in 29 tumors (63%), of which 13 (28%) showed different patterns of a partial loss of 22q. However, the NF2 locus was retained in one tumor that lost a more distal part of 22q. Moreover, 27 of the 28 tumors which showed LOH at the NF2 locus also lost alleles at more telomeric loci. These results raise the possibility that another tumor-suppressor gene for meningioma may exist on 22q and that its localization may be distal to the D22S102 locus.

Chromosome Deletion↗

An EcoRI RFLP in human APC gene.

A novel EcoRI-restriction fragment length polymorphism in the genomic sequence of the human adenomatous polyposis coli (APC) gene is described. This polymorphism in the APC gene would be very useful for examination of segregation of the mutated APC gene in the kindreds of familial adenomatous polyposis, and also for studying the loss of heterozygosity at the APC region in certain tumors.

Deoxyribonuclease EcoRI↗

Role of micro-chimerism in inducing immunological tolerance by intraportal injection of donor spleen cells in rats.

Recently, we reported that intraportal (IP) injection of donor spleen cells (SPCs) prevented liver allograft rejection. Moreover, we developed a new method using polymerase chain reaction (PCR)-mediated restriction fragment length polymorphism (RFLP) analysis, and demonstrated micro-chimerism (MC) at the DNA level in the spleen 14 days after IP injection. In the present study, the long-term presence of injected allogeneic SPCs was investigated at the cellular level by immunofluorescence staining as well as the DNA level using RFLP analysis. Male ACI (RT1a) rats were used as the donors and Lewis (RT1(1)) rats as the recipients. After DNA preparation from the lymphoid organs, RT1B beta domain 1 region was amplified by PCR, and RFLP analysis was performed with PvuII restriction enzyme. In the immunofluorescence staining, the monoclonal antibody, MN4-91-6, was used to detect the injected donor ACI SPCs in a frozen specimen. We did not detect MC in Lewis rats intravenously injected with 5 x 10(7) ACI SPCs on day 14. On the other hand, stable chimerism in the spleen was observed in intraportally injected rats up to 28 days after injection at not only the DNA level but also the cellular level. No chimerism was detected in other organs (including the thymus, lymph nodes, and liver). In conclusion, the long-term presence of injected allogeneic SPCs in the spleen was demonstrated after IP injection but not after IV injection, and this phenomenon may be one of the mechanisms involved in portal venous immunosuppression.

Animals↗

Detection of an increase in ascorbate radical in an irradiated experimental tumour system using ESR.

We measured Asc.- (ascorbate radical) produced by the reaction of AscH- (ascorbic acid) with HO. or O2.- after irradiation in mouse. It is possible to measure Asc.- easily using ESR and a dialysis method in which Asc.- was collected at room temperature in the interstitial fluid through the dialysis membrane. After irradiation, Asc.- increased in both normal muscle and tumour tissues (SCC-VII) in proportion to the radiation dose. Asc.- increased after treatment with the agents H2O2 and FeCl2, while it decreased after treatment with SOD and catalase. These results suggest that the amount of HO. and O2.- produced is reflected in the Asc.- production. Also, the increase in Asc.- production when WR-2721 was administered prior to irradiation was less than for experiments in which irradiation only was performed. This method is useful for the following reasons. First, no special treatment, such as freezing of the sample, and no administration of noxious agents are necessary to measure Asc.-. Second, irradiation using a dose of only a few Gy shows an increase in production of Asc.-. Third, this method does not require removal of organs. Using this method, Asc.- can serve as an indicator of the amount of HO. and O2.- produced by irradiation in vivo.

Amifostine↗

Inhibitory effects of 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), green tea catechins and other antioxidants on 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1)-induced rat hepatocarcinogenesis and dose-dependent inhibition by HTHQ of lesion induction by Glu-P-1 or 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx).

The effects of 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), green tea catechins (GTC), alpha-tocopherol, beta-carotene, chlorophyllin, phenylethylisothiocyanate (PEITC), 3-O-ethylascorbic acid (EAsA), 3-O-dodecylcarbomethyl ascorbic acid (DAsA), n-tritriacontane-16,18-dione (TTAD) and d-limonene on 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1)- or dimethylnitrosamine (DMN)-induced hepatocarcinogenesis, and the dose dependence of HTHQ inhibition of Glu-P-1- or 2-amino-3,8-dimethylimidazo [4,5-f]quinoxaline (MeIQx)-influence on lesion development were examined in a rat medium-term liver bioassay system featuring diethylnitrosamine initiation and partial hepatectomy. At the end of week 8, the number and total area of glutathione S-transferase placental form (GST-P) positive liver foci in rats treated with 0.03% Glu-P-1 alone were increased significantly (46.8 +/- 11.0 and 12.0 +/- 5.6 respectively) as compared to the control values (3.8 +/- 1.6 and 0.4 +/- 0.2). Combined treatment with 1% HTHQ remarkably reduced both of these parameters (8.1 +/- 2.1 and 0.6 +/- 0.2). GTC (1%), PEITC (0.1%), beta-carotene (0.1%) and DAsA (1%) also demonstrated inhibition but less than HTHQ. On the other hand, these antioxidants did not influence development of foci initiated by 0.002% DMN. In the dose-response study, up to 0.125% HTHQ significantly reduced the effects of 0.02% Glu-P-1 or 0.03% MeIQx on the number and area of foci. These results indicate that several antioxidants exert chemopreventive effects against heterocyclic amine (HCA)-induced hepatocarcinogenesis, and particularly HTHQ which thus deserves further attention as a chemopreventor in the contest of the environmentally important HCA group of carcinogens.

Animals↗

Chemoprevention of 2-amino-1-methyl-6-phenylimidazo[4,5-b]-pyridine (PhIP)-induced mammary gland carcinogenesis by antioxidants in F344 female rats.

Chemopreventive effects of the antioxidants 1-O-hexyl-2,3,5- trimethylhydroquinone (HTHQ), 3-O-ethylascorbic acid (EAsA), 3-O-dodecylcarbomethylascorbic acid (DAsA), green tea catechins (GTC) and ellagic acid on 2-amino-1-methyl-6- phenylimidazo[4,5-b]pyridine (PhIP)-induced mammary carcinogenesis were examined in female F344 rats. Groups of 20-21 6-week-old rats were maintained on a powdered diet containing 0.02% PhIP alone, PhIP together with 0.5% HTHQ, 1% EAsA, 1% DAsA, 1% GTC or 0.1% ellagic acid, these antioxidants alone or basal diet alone without supplement for 52 weeks. The survival rates of PhIP plus antioxidant groups at the end of the experiment were higher than that of the PhIP alone group. Sequential observation of palpable mammary tumors demonstrated only one tumor by week 52 in the PhIP plus HTHQ group, whereas 40% of the rats receiving PhIP alone had tumors by this time point. The final incidence of mammary adenocarcinomas was significantly decreased in the PhIP plus HTHQ group (4.8%, P < 0.01) as compared to the PhIP alone value (40%). Although statistically not significant, incidences of adenocarcinomas in the other antioxidant-treated groups (23.8-28.6%) were also lower than in the PhIP alone group. Furthermore, the incidence of large intestinal tumors in the PhIP plus HTHQ group (0%) showed a tendency to decrease relative to the PhIP alone group (16.7%). These results indicate that antioxidants, particularly HTHQ, exert a potent chemopreventive action against PhIP-induced carcinogenesis.

Adenocarcinoma↗

Isolation and characterization of a novel gene deleted in DiGeorge syndrome.

The region commonly deleted in DiGeorge syndrome (DGS) has been localized at 22q11.1-q11.2 with the aid of a high resolution banding technique. A 22q11 specific plasmid library was constructed with a microdissection and microcloning method. Dosage analysis proved three of 144 randomly selected microclones to detect hemizygosity in two patients with DGS. Two of the clones were found to contain independent low-copy-number repetitive sequences, all of which were included in the region deleted in the DGS patients. Screening of the cosmid library and subsequent cosmid walking allowed us to obtain two cosmid contigs corresponding to the microclones within the deletion (contig 1 and contig 2), whose order fluorescence in situ hybridization identified as centromere-contig 1-contig 2-telomere on 22q. By direct selection strategy using one of the cosmids of contig 1, a 4.3 kb cDNA was obtained from fetal brain cDNA library. Sequence analysis of the cDNA revealed an open reading frame encoding 552 amino acids which had several characteristics of DNA-binding proteins. The gene, designated LZTR-1, which was transcribed in several essential fetal organs, proved to be hemizygously deleted in seven of eight DGS patients or its variants, but not in one DGS patient and GM00980. Although LZTR-1 does not locate in the shortest region of overlap, several of its structural characteristics identifying it as transcriptional regulator suggest that it plays a crucial role in embryogenesis and that haploinsufficiency of this gene may be partly related to the development of DGS.

Amino Acid Sequence↗

Defective IL-5-receptor-mediated signaling in B cells of X-linked immunodeficient mice.

Murine (m) IL-5 induces proliferation and differentiation of both Ly-1+ B cells and activated conventional B cells. X-linked immunodeficient (XID) mice do not respond to thymus-independent type II antigens, and have an abnormal response to a variety of activation signals through Ig receptors, CD40 and cytokine receptors. Furthermore, XID mice show a B cell specific defect, reflected in decreased numbers of IL-5R alpha+ B cells and reduced responsiveness of IL-5R alpha+ B cells to mIL-5. We generated IL-5R alpha transgenic (5R alpha-Tg) mice in which B cells expressed recombinant IL-5R alpha. We crossed male 5R alpha-Tg mice with female XID mice and used their offspring to determine the IL-5 responsiveness of these B cells. All B cells of F1 male mice carrying the xid gene together with the transgene expressed the recombinant IL-5R alpha. However, those mice lacked Ly-1 B cells and their B cells acquired responsiveness to mIL-5. Interestingly, XID-5R alpha-Tg B cells, but not XID B cells, acquired mIL-5 proliferative and Ig-secretory responsiveness only in the presence of suboptimal doses of lipopolysaccharide. Stimulation of these B cells with mIL-5 plus phorbol myristate acetate induced proliferation, but not Ig secretion. These results indicate that the impaired mIL-5 responsiveness of B cells in XID mice is due to an abnormality of IL-5R-mediated signaling which may correlate with the xid gene mutation, alteration of a single amino acid of Bruton's tyrosine kinase.

Agammaglobulinaemia Tyrosine Kinase↗

Shwachman syndrome associated with de novo reciprocal translocation t(6;12)(q16.2;q21.2).

We describe a de novo apparently balanced reciprocal translocation t(6;12)(q16.2; q21.2) in an 18 month old girl with Shwachman syndrome, characterised by exocrine pancreatic insufficiency and bone marrow dysfunction. The cause of this syndrome is unknown, although autosomal recessive inheritance has been proposed. The translocation breakpoints in the present patient may be candidate regions for a gene responsible for Shwachman syndrome.

Abnormalities, Multiple↗

Hypercalciuria and nephrocalcinosis in patients with idiopathic low-molecular-weight proteinuria in Japan: is the disease identical to Dent's disease in United Kingdom?

Idiopathic low-molecular-weight (LMW) proteinuria is a newly described renal disease in Japan and Italy. We report on 7 patients who manifested bilateral or unilateral nephrocalcinosis, as demonstrated by abdominal computed tomography scans. Renal histology revealed calcinosis of renal tubules in 2 patients. Computed tomography is a reliable method for the detection of nephrocalcinosis in this disorder. Hypercalciuria was also seen in 6 patients. A calcium-loading test performed in 2 patients suggested that hypercalciuria was of renal origin. Although the true pathogenesis is still not known, hypercalciuria and nephrocalcinosis appear to be a common complication in patients with idiopathic LMW proteinuria. These complications and clinical features suggest that idiopathic LMW proteinuria in Japan is likely to be identical to Dent's disease in the United Kingdom.

Adolescent↗

[A case of rhinocerebral phycomycosis].

Rhinocerebral phycomycosis is an uncommon opportunistic infection with ubiquitous fungi of the class Phycomycetes, starting in the nose and extending to the paranasal sinuses and then intracranially. The condition is often characterized by poor prognosis because of occlusion of the internal carotid artery. This disease is commonly associated with predispositions such as uncontrolled diabetes mellitus, which is the most common, immunosuppressive states and metabolic bankruptcy including leukemia, lymphoma, myeloma, malnutrition, uremic or diarrheal acidosis, severe burns, anemia, carcinoma, radiotherapy, liver cirrhosis, hemochromatosis, tuberculosis, septicemia, long-term medication of steroid, antibiotics and antimetabolite, drug addiction, cytotoxic drug administration and AIDS. Cases with unknown predisposition, however, have been infrequently reported in the literature. The authors report a case of rhinocerebral phycomycosis in which concurrence of Candida species instead of the above-mentioned common predispositions was considered a potential predisposition. To our knowledge, only 1 report in which Candida species are referred to as a potential predisposition for this disease has been previously issued. A 85-year-old man was admitted to our hospital on March 2, 1994 because of generalized convulsion. He had received a total extirpation of an ascending colon cancer in July 1993. On admission, physical inspection showed no abnormalities and neurological examination revealed obtunded consciousness without other abnormalities. He had no diabetes mellitus. Hematological and blood chemistry values were normal except for CA19-9 of 45 U/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Evidence for an immunological pathogenesis of thrombocytopenia in chronic liver disease.

OBJECTIVES: To elucidate the role of platelet-associated IgG (PA-IgG) in the mechanism of thrombocytopenia associated with chronic liver disease. METHODS: Platelet count in blood, PA-IgG, and scintigraphic spleen/liver ratio as a marker of splenomegaly was examined in 214 individuals, including 16 controls showing nonspecific reactive change in liver biopsy and 198 patients with chronic liver disease. RESULTS: The mean blood platelet count decreased significantly according to severity of liver disease, from control to liver cirrhosis. PA-IgG levels increased significantly in relation to severity of liver disease, as did spleen/liver ratio. In chronic hepatitis or liver cirrhosis, an inverse correlation was found between platelet counts and PA-IgG levels. An inverse correlation was also observed between platelet count and spleen/liver ratio in liver cirrhosis. The splenic embolization resulted in a significant rise in platelet count and a significant fall in PA-IgG in the 14 cirrhotic patients. CONCLUSIONS: These results may give support to evidence for an immunological mechanism mediated by PA-IgG for the thrombocytopenia occurring in chronic liver disease. In the case of liver cirrhosis, this mechanism would act in addition to platelet pooling in the spleen on thrombocytopenia. PA-IgG may also have an important role in thrombocytopenia associated with chronic hepatitis, in which splenic platelet pooling is less marked.

Adult↗

[Measurement of radical in irradiated experimental tumor: direct detection of ascorbate radical in mice using ESR].

We measured ascorbate radical (AR) produced by the reaction of ascorbic acid (Asc) with hydroxyl radical (.OH) or superoxide (O2-) after irradiation in normal muscle and SCC-VII tumor of C3H/He mice. AR can be measured using electron spin resonance (ESR) equipment and the dialysis method. The tube for collecting AR was inserted such that the dialysis membrane was in contact with the normal thigh or the center of the tumor lesion. The AR in the interstitial fluid around the membrane was collected through the dialysis membrane. After irradiation with 10 Gy, AR increased in both the normal muscle and tumor tissue; the percent increase was 53.1% for normal muscle tissue and 33.8% for tumor tissue. The maximum percent increases in AR in the normal muscle and the tumor tissue were 11.7 and 9.5% for 2.5 Gy, 28.5 and 18.5% for 5 Gy, 53.1 and 33.8% for 10 Gy, and 88.5 and 44.8% for 15 Gy, respectively. The amount of AR increased to maximums of 144.3% and 160.1% after treatment with H2O2 and FeCl2, respectively, while it decreased to minimums of 65.3% and 81.3% after treatment with superoxide dismutase (SOD) and catalase, respectively. These results suggest that the amount of .OH and O2- is reflected in the amount of AR production. This method is useful for the following reasons. First, no special treatment, such as freezing of the samples, and no administration of noxious agents are necessary. Second, irradiation using a dose of only several Gy shows an increase in the production of AR. Third, this method is less invasive.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

[Study of anti-tumor effects of hyperthermia combined with hydralazine on experimental tumor].

We analyzed tumor growth delay in experimental tumors after hyperthermia alone, hydralazine (HDZ) injection alone and the combination of these modalities. We also analyzed the energy parameter (ATP/Pi ratio) obtained by 31P-MRS (magnetic resonance spectroscopy). The purpose of this study was to evaluate the usefulness of 31P-MRS as an index of anti-tumor effect. FM3A tumor cells were transplanted subcutaneously in the hind legs of C3H/He mice. We dipped the tumors into a heated circulating water bath. 31P-MRS was performed with a CSI spectrometer. The anti-tumor effect obtained with HDZ alone was insignificant, but combined treatment with hyperthermia and HDZ had a significant synergistic effect. The ATP/Pi ratios for all groups treated separately with HDZ or hyperthermia were not different from the control, but the ATP/Pi ratio decreased after combined use of these agents. There was a significant correlation between the decrease in ATP/Pi ratio and tumor growth delay. We observed a direct relation between the delay in tumor growth and the decline in ATP/Pi ratio after combined treatment with HDZ and hyperthermia. The ATP/Pi ratio 24 hr after treatment may be useful in predicting the efficacy of the combined use of HDZ and hyperthermia.

Adenosine Triphosphate↗

Inhibition of mammary gland carcinogenesis by green tea catechins and other naturally occurring antioxidants in female Sprague-Dawley rats pretreated with 7,12-dimethylbenz[alpha]anthracene.

Effects of the naturally occurring antioxidants on mammary gland carcinogenesis were examined in female Sprague-Dawley rats pretreated with 7,12-dimethylbenz[alpha]anthracene (DMBA). Groups of 15-16 7-week-old rats received a 50 mg/kg body weight intra-gastric dose of DMBA, and starting one week thereafter placed on diet containing 0.4% catechol, 1.0% gamma-oryzanol, 2.0% phytic acid, 1.0% green tea catechins (GTC), 1.0% tannic acid or basal diet alone for 35 weeks. Although the final incidences and multiplicities of mammary tumors were not significantly different between DMBA-treated groups, the numbers of survivors in the antioxidant-treated groups at the end of the experiment at week 36 were significantly higher than in the basal diet group. In particular, the survival rate of the GTC group at 93.8% strongly contrasted with that of only 33.3% for rats on the basal diet. At the end of week 18, when all the animals were still alive, the average size of palpable mammary tumors was significantly smaller in the catechol, phytic acid and catechins groups. These results indicate that antioxidants, and GTC in particular, inhibit rat mammary gland carcinogenesis after DMBA initiation.

9,10-Dimethyl-1,2-benzanthracene↗

Hydralazine at thermoradiotherapy: tumor size and blood flow effects.

PURPOSE: This study was aimed to assess the dependence on tumor size and blood flow of the efficacy of a vasoactive drug hydralazine with thermoradiotherapy. METHODS AND MATERIALS: Experiments were performed on mice bearing SCC-VII tumors with volumes of about 85 and 340 mm3 (7-8 or 11-12 days after transplantation, respectively). Local hyperthermia (water bath, 43 degrees C, 0.5 h) was started 3 h after irradiation of tumors. Hydralazine (2.5 mg/kg, IP) was given 0.5 h before heating. Tumor blood flow was evaluated by laser Doppler flowmetry before, during and up to 2 days after the treatments. RESULTS: It was shown that hydralazine and hyperthermia, even in combination with each other, had very weak anti-tumor effect, especially for 85 mm tumors. The agents also insignificantly enhanced the efficacy of radiotherapy excluding the case of polyradiomodification for 340 mm3 tumors when a dose modifying factor of about 2.0 was achieved. Thermometry showed only a small improvement by HDZ in heating patterns of tumors of both sizes. Meanwhile, the therapeutic efficacy of hydralazine and heat was correlated with the changes in tumor blood flow, first of all with the delayed effects. The radiomodifiers induced only minor and transient suppression of perfusion in the smaller tumors, and more markedly and for longer time decreased blood flow in the larger tumors. In the latter case, the inhibiting effect of the drug plus hyperthermia remained for at least 48 h after the treatment. CONCLUSION: (a) The combined use of hydralazine and heat seems to be advisable only at radiotherapy of rather large advanced tumors; (b) the efficacy of such radiomodification is correlated with prolonged inhibition of tumor blood flow by these agents; and (c) hydralazine and hyperthermia are likely to kill selectively both acutely and chronically hypoxic radioresistant cancer cells.

Animals↗