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Biomedical subjects

T Ichikawa

Publications and source records attributed to T Ichikawa.

At least 253 records · Page 14Linked to original sources
PubMed1997

Clinical investigation of neuroblastoma with partial deletion in the short arm of chromosome 1.

Several loci on the short arm of chromosome 1 (1p) have been reported as the consensus deleted regions for the putative suppressor genes of neuroblastoma by deletion mapping. The significance of deletion in 1p on the clinical features of neuroblastoma remains controversial. To clarify the relationship between the clinical features of neuroblastoma cases and genetic status of 1p, we performed deletion mapping on 1p on samples obtained from 58 cases with neuroblastoma using 12 highly polymorphic microsatellite or minisatellite loci. Loss of heterozygosity of 1p was detected in 19 cases (33%) of primary tumors and in 21 cases (36%) when metastatic and recurrent sites were included. They were classified into two groups according to the 1p deletion pattern: interstitial deletion (group I, n = 11) and terminal deletion (group T, n = 10). The shortest region of overlap in group I ranged between FGR and D1S170 (1p36.1-2). Clinically, all group I cases survived disease free, and none of these cases showed MYCN amplification. However, in group T, eight (80%) cases showed a large terminal deletion from D1S162 (1p32-pter), including the shortest region of overlap of group I, and two (20%) showed a very terminal deletion from D1S160 (1p 36.3). Of the group T cases, only two survived disease free, and seven (70%) showed MYCN amplification. Thus, the candidates for the locations of neuroblastoma suppressor genes on 1p may involve at least two regions, which demonstrate different clinical features.

Chromosome Mapping↗
PubMed1996

Isolation of cDNA clones of the rat mRNAs expressed preferentially in the prenatal stages of brain development.

For better understanding of the molecular mechanisms underlying the developmental processes of the mammalian brain, we isolated rat fetal brain-enriched (FBE) cDNA clones, whose corresponding mRNAs were expressed at least 5-fold more in the fetal brain than in the adult brain. Our modified differential screening procedure, which utilized a two-vector (pT7T3D and pBluescript) system and showed low background levels of colony hybridization for screening, efficiently identified 64 candidate FBE clones from a small number (475) of colonies in the fetal brain cDNA library. After subsequent second screening of the candidate FBE clones by Northern blot analysis, we successfully isolated 22 distinct FBE clones. The nucleotide sequence analysis of the 22 FBE clones revealed that 13 of them had no significant matches to the sequences reported in the databases, whereas 9 of them matched previously reported sequences (alpha-tubulin M alpha 1, beta-tubulin M beta 5, thymosin-beta 10, stathmin, beta-tubulin M beta 2, alpha-internexin, ferritin Lg chain, neuronatin and amphoterin), most of which have been shown to be down-regulated during brain development. We also found that the Northern blot analysis in the second screening could be replaced by cDNA library DNA-Southern blot analysis, in most clones corresponding to relatively abundantly expressed mRNAs. Thus, once the cDNA library is constructed, clone selection will be possible in such clones without the use of additional RNA or Northern blot in screening, allowing the analysis of small brain regions of interest.

Animals↗
PubMed1996

The activation of K-ras gene at an early stage of lung tumorigenesis in mice.

To clarify the exact timing of K-ras gene mutational activation in lung tumorigenesis of mice, we applied a sensitive mutant allele specific amplification (MASA) method to pulmonary DNA from urethane-treated mice. The activation of K-ras gene with 61st codon AT mutation was detected in the lungs of mice at day 14 but not day 7 after urethane treatment by MASA. The mutation of MASA products was also checked by XbaI restriction fragment length polymorphism analysis and DNA sequencing. These data suggest that the mutation of K-ras gene in the lungs of mice treated with urethane occurred at the early stage of lung tumorigenesis.

Animals↗
PubMed1996

Structural organization and chromosomal assignment of the human 14-3-3 eta chain gene (YWHAH).

14-3-3 protein, a brain-specific protein, is thought to be a multifunctional protein involved in the activation of tyrosine and tryptophan hydroxylases, the inhibition or activation of protein kinase C, and the activation of signal transduction. The human 14-3-3 eta chain gene was isolated and its structure was determined. It is composed of two exons separated by one long intron (approximately 8 kb) and spans about 10 kb. A transcription initiation site was identified by a combination of S1 nuclease mapping, primer extension analysis, and RACE methods. In the 5'-flanking region, we found four GC box sequences, four anti-GC box sequences, a TATA box-like sequence, CAAT box-like sequences, a C/EBP element, two AP-2 sequences, an AP-3 sequence, an Oct-6-like sequence, six E boxes, and a CRE sequence. FISH with DNA probes of the human 14-3-3 eta chain gene mapped the 14-3-3 eta chain gene to chromosome 22q12.1-q13.1.

14-3-3 Proteins↗
PubMed1996

Stimulation of mucin biosynthesis in rat gastric mucosa by FRG-8813 and its structural analogs.

Certain chemical properties, which may determine the stimulatory actions of the new histamine H2 receptor antagonist, FRG-8813 (2-(furfurylsulfinyl)-N-(4-[4-(piperidinomethyl)-2-pyridyl]o xy-(Z)- 2-butenyl)acetamide), on mucin biosynthesis, were identified by considering the derivation of this drug using an organ culture system of the rat stomach. [3H]Glucosamine and [35S]sulfate incorporation was stimulated in the corpus region by FRG-8813 and its structural analog, compound A (N-[4-[[4- (piperidinylmethyl)pyridyl]-2-oxy]-(Z)-2-butenyl]phthalimide). The chronotropic response to histamine in the guinea pig right atria was suppressed by FRG-8813 in a concentration-dependent fashion. In contrast, compound A did not suppress the histamine-induced response. Ranitidine at 10(-4) M did not suppress the FRG-8813-induced increase in [3H]glucosamine incorporation into mucin. These results suggest that the pyridine derivative and amide structure are chemically important in FRG-8813 as a stimulant on mucus metabolism. Also, this effect is not directly due to histamine H2 receptor antagonism.

Acetamides↗
PubMed1996

Mapping of metastasis suppressor gene(s) for rat prostate cancer on the short arm of human chromosome 8 by irradiated microcell-mediated chromosome transfer.

Our previous studies demonstrated that human chromosome 8 contains metastasis suppressor gene(s) for rat prostate cancer. However, it is still unknown which portion of human chromosome 8 is associated with suppression of metastatic ability, because all of the clones in which metastatic ability is suppressed contain at least one copy of intact human chromosome 8. In the present study, we used the irradiated microcell-mediated chromosome transfer technique to enrich for specific chromosomal arm deletions of selected chromosomes. The resultant series of human chromosomes 8 with a variety of chromosomal deletions was introduced into highly metastatic Dunning rat prostate cancer cells. All of the resultant microcell hybrids showed reduced metastatic ability. To obtain a smaller size of human chromosome 8 and to locate further the region of metastasis suppressor gene(s), the most reduced size of human chromosome 8 that was generated with the initial irradiated chromosome transfer was retransferred into the Dunning cancer cells without irradiation. The resultant microcell hybrids were analyzed to determine which portion of human chromosome 8 suppressed the metastatic ability of the recipient cells. This analysis demonstrates that the portion of human chromosome 8 containing metastasis suppressor gene(s) for rat prostate cancer cells lies on human chromosome segment 8p21-p12, where frequent allelic losses have been detected in allelotype analyses of human prostate cancer. This suggests that one of the metastasis suppressor genes for rat prostate cancer on human chromosome 8 may also play an important role in the progression of human prostate cancer.

Animals↗
PubMed1996

Prostate cancer--biology of metastasis and its clinical implications.

Prostate cancer is one of the most commonly diagnosed cancers and is a major cause of cancer death in men. Although the majority of the diagnosed prostate cancers will remain localized and never produce clinical symptoms during the lifetime of the host, a subset of these cancers will progress to a more malignant state requiring therapeutic intervention. Acquisition of metastatic ability by prostatic cancer cells is the most lethal aspect of prostatic cancer progression. Once this has occurred, definitive therapy is required before the initially localized metastatic cells escape from the prostate. At present, metastatic prostate cancer is incurable. Therefore, there is an urgent need to develop molecular markers that can be used to predict the metastatic potential of prostate cancers. Using somatic cell hybridization, we have demonstrated that acquisition of metastatic ability requires both the loss of metastasis-suppressor function(s) and the activation of oncogenes. In further studies using micro-cell-mediated chromosomal transfer, we located genes on human chromosome, 8, 10cen-q23, 11p11.2-13, and 17pter-q23, which, when introduced into rat prostatic cancer cells, are capable of suppressing their metastatic ability without affecting their tumorigenicity or growth rate in vivo. Initially we focused upon the human chromosome 11p11.2-13 region to clone metastasis-suppressor gene(s) positionally. One such gene, termed KAI-1, encodes a membrane glycoprotein. KAI-1 has been mapped to the p11.2 region of human chromosome 11 by fluorescence in-situ hybridization analysis. Expression of KAI-1 has been detected in all normal human tissues thus far tested, including prostate tissue. When introduced into rat metastatic prostatic cancer cells, KAI-1 significantly suppressed the metastasis without affecting the tumor growth rate. KAI-1 expression is high in human normal prostate and benign prostatic hyperplasia but is dramatically lower in cancer cell lines derived from metastatic prostate tumors.

Animals↗
PubMed1996

Glass wool filtration reduces reactive oxygen species by elimination of leukocytes in oligozoospermic patients with leukocytospermia.

PURPOSE: Two types of glass wool were used to remove leukocytes in semen for evaluation of reactive oxygen species production by spermatozoa in oligozoospermic patients with leukocytospermia. METHODS: Semen samples were prepared using fine-structure glass wool (SpermFertil) and coarse-structure glass wool. In each treatment group, native semen was evaluated for sperm concentration, percentage motility, viability, leukocyte concentration, and production of reactive oxygen species. RESULTS: Electron microscopically, SpermFertil showed a higher number of leukocytes attached to the fibers compared to coarse-structure glass wool. Leukocytes in native semen and after glass wool filtration as determined by peroxidase cytochemistry confirmed this observation. Reactive oxygen species decreased from 45.303 counts/10(7) viable cells in native semen to 15.806 counts/10(7) cells in coarse structure wool and 7.465 counts/10(7) cells in Spermfertil, respectively. CONCLUSIONS: Removal of leukocytes from semen of oligozoospermic patients by means of glass wool filtration is a useful method to distinguish production of reactive oxygen species by leukocytes versus sperm cells.

Glass↗
PubMed1996

Mechanisms for cytoprotection by vitamin U from ethanol-induced gastric mucosal damage in rats.

A comparison was made of the effects of a nonsulfhydryl compound, vitamin U (methylmethioninesulfonium chloride, MMSC), and a sulfhydryl compound, cysteine (Cys), with regard to the inducement of acute gastric mucosal damage in the presence and absence of N-ethylmaleimide (NEM), a sulfhydryl-blocking reagent. The effects of MMSC, Cys, or NEM on gastric mucin content were examined using a newly developed biochemical method. MMSC and Cys inhibited mucosal damage due to 50% ethanol. The preinjection of NEM had no effect on cytoprotection of prostaglandins, but prevented the effects of Cys and MMSC. MMSC and Cys increased surface mucin content but lessened that of deep mucin. NEM decreased surface mucin and increased deep mucin. It thus follows that sulfhydryl compounds accelerate the secretion of deep mucin and accumulate surface mucin. The cytoprotective mechanism of MMSC may thus be mediated by sulfhydryl compounds, and the increase in surface mucosal mucin may possibly be related to cytoprotection.

Animals↗
PubMed1996

Intracranial metastases of hepatocellular carcinoma: CT and MRI.

We report clinical characteristics and CT and MRI in 16 patients with brain metastases due to hepatocellular carcinoma (HCC). Eight of these 16 patients presented with apoplexy-like symptoms (50%). Pulmonary metastases were found in 13 cases (81.3%). The mean survival from the appearance of cerebral metastases to death was 6.2 weeks, which is one of the shortest survival terms in metastatic brain tumours. Haemorrhagic brain metastases were observed in 14 patients (87.5%) with a tendency for the frequency of bleeding to increase in proportion to the size of the tumour. On both contrast-enhanced CT and MRI, metastatic brain tumours enhanced strongly, suggesting that brain metastases, like HCC, are also hypervascular. MRI is useful in evaluating brain metastases from HCC, especially in order to differentiate tumour from haemorrhage. Our results demonstrated a poor prognosis and bleeding tendency of brain metastases due to HCC and showed the usefulness of CT and MRI in achieving a correct diagnosis.

Adult↗
PubMed1996

Activity of the intercostal muscle spindle afferents in the lower thoracic segments during spontaneous breathing in the cat.

Intraaxonal recordings of 33 spindle afferents from the inspiratory (n = 8) and expiratory (n = 25) intercostal muscles in the lower thoracic segment (T9-11), were made during spontaneous breathing in the anesthetized cat. All of them showed respiration-related activity. However, only three spindle afferents (one from the inspiratory and two from the expiratory intercostal muscles) showed higher firing frequency during the active contraction phase of the receptor-bearing muscle. The remaining 30 spindle afferents (seven from the inspiratory and 23 from the expiratory muscles) showed the maximum firing discharge during the passive stretch phase of the parent muscles. On the other hand, in the middle thoracic segments (T6-7), five of six spindle afferents from the inspiratory muscles and four of nine spindle afferents from the expiratory muscles showed maximum firing rate during parent muscle contraction in agreement with previous study. These results suggest that the spindle activity in the lower thoracic segments is dominated by muscle length changes, whereas that in the middle thoracic segments is largely via the fusimotor pathway.

Animals↗
PubMed1996

Studies on an experimental system for the invasion of Theileria sergenti merozoite into erythrocytes.

The entry of Theileria sergenti merozoite into erythrocytes was examined to establish an in vitro experimental system for merozoite invasion. Free merozoites (1 x 10(8)) were incubated with erythrocytes (2 x 10(7)) in RPMI-1640 containing various concentrations of fetal bovine serum (FBS). The invasion assay was examined at various temperatures and pH concentrations. The results showed that merozoite invasion was accelerated by the addition of FBS and by incubation at 37 degrees C at pH 6.5-7.5. To investigate how enzymatic activity contributes to the entry of T. sergenti merozoites, the inhibitory effect on the merozoite invasion was examined by using protease inhibitors. An inhibitory effect on the invasion of merozoites was observed in the medium containing 1,10-phenanthroline and ethylenediaminetetraacetic acid disodium salt which are classified as metalloprotease inhibitors. The results suggest that FBS plays an important role in the effective invasion of merozoite into erythrocytes and that enzymatic activity may affect the invasion of merozoite into the host cell.

Animals↗
PubMed1996

Exposure of postnatal rats to glucocorticoids suppresses the development of choline acetyltransferase-immunoreactive neurons: role of adrenal steroids in the development of forebrain cholinergic neurons.

Rat forebrain cholinergic neurons undergo dynamic developmental changes, showing a continuous increase in choline acetyl-transferase (ChAT) activity, during the early postnatal period. In adult rats, increases in circulating glucocorticoids result in decreases in activity of forebrain neuronal ChAT, thus raising the possibility that postnatal development of forebrain cholinergic neurons results from low levels of these hormones. In the rat, the first 2 weeks postnatally are characterized by very low levels of adrenal steroids. To understand the role of endogenous glucocorticoids in the development of forebrain cholinergic neurons, we studied the changes in ChAT immunoreactivity in forebrain cholinergic neurons of postnatal rats which had received daily subcutaneous injection of the synthetic glucocorticoid dexamethasone for 8 days. Immunohistochemical analysis of the rat pup forebrain revealed nearly complete obliteration of ChAT-immunoreactive neurons in the caudate-putamen, especially in the dorsolateral region of the rostral part. At the same stage, treatment with dexamethasone induced significant decreases in both number and length of dendritic branches of ChAT-immunoreactive neurons in the substantia innominata and the diagonal band. Despite the marked alterations in the caudate-putamen and diagonal band, the ChAT-immunoreactive neurons in other forebrain structures such as globus pallidus and medial septal nucleus showed little change. In the caudate-putamen, Nissl staining and specific labeling for nuclear DNA fragmentation exhibited no increase in number of dying cells following dexamethasone treatment, therefore indicating that the loss of ChAT immunoreactivity is not due to glucocorticoid-induced cholinergic cell death. These observations demonstrated that the development of cholinergic neurons in rat pups was inhibited by prolonged glucocorticoid exposure, suggesting that low levels of adrenal steroids may promote the postnatal development of these neurons.

Adrenal Cortex Hormones↗
PubMed1996

Cloning, sequence analysis, and expression in Escherichia coli of the gene encoding the Candida utilis urate oxidase (uricase).

A urate oxidase (uricase) gene was cloned from Candida utilis with an oligonucleotide probe based on the amino acid sequence of cyanogen bromide-cleaved uricase. The uricase gene contains 909 base pairs and encodes a protein with a predicted mass of 34,193 Da. Candida uricase was similar (49% match in amino acid sequence) to the uricase from Aspergillus flavus. The uricase from Candida utilis has four cysteines and one of them, Cys168, participates in the enzyme activity. This enzyme was expressed to a level of about 20% of total cellular protein in an Escherichia coli cell as a soluble and functional form.

Amino Acid Sequence↗
PubMed1996

Primary malignant lymphoma of the brain: demonstration of frequent p16 and p15 gene deletions.

The p16 (MTS-1) gene, a candidate tumor suppressor gene, was examined by means of Southern blot, PCR-SSCP (polymerase chain reaction-single-strand conformation polymorphism) and nucleotide analyses in 5 cases of primary malignant lymphoma of the brain. By Southern blot analysis, the p16 gene was found to be deleted in at least 4 cases, homozygously (3 cases) or hemizygously (1 case). The p15 (MTS-2) gene, another candidate tumor suppressor gene located in the vicinity of the p16 gene, to which it shows structural and functional similarity, was also found to be deleted in 4 cases. Our frequent detection (80%) of p16 and p15 gene deletions might suggest that these deletions are closely related to carcinogenesis in primary malignant lymphoma of the brain. SSCP and nucleotide analyses revealed no mutations of the p16 gene in any of the cases.

Adult↗
PubMed1996

A comparative study of glioma cell lines for p16, p15, p53 and p21 gene alterations.

A total of 10 glioma cell lines were examined for alterations of the p16, p15, p53 and p21 genes, which are tumor suppressor genes or candidates with direct or indirect CDK-inhibitory functions. Genetic alterations (deletions or mutations) were frequently seen in the p16, p15 and p53 genes in these cell lines, but not in the p21 gene. When the states of the p16, p15 and p53 genes were compared among cell lines, all the cell lines showed abnormalities in at least 1 gene, often in 2 or 3 genes coincidentally, suggesting that dysfunction of these genes is closely related to glioma cell growth. Although alteration of all 3 genes was most frequent, there were cell lines having either p16/p15 or p53 or pl6 and p53 gene alterations, suggesting that the time order of these genetic alterations was variable depending on the cell line. Among cell lines examined, one with homozygous p53 gene deletion seemed of particular practical value, since such a cell line might be useful in various studies, including investigation of the functions of various mutant p53 genes in the absence of heteromeric protein formation. On examination of the primary tumor tissues, the same alterations of the p16/p15 and p53 genes as detected in the cell lines were demonstrated in all 6 cases examined: p16/p15 gene deletion in 1, p16 gene mutation in 1 and p53 gene mutations in 5 cases. This suggested that the p16/p15 and the p53 gene alterations and their combinations in at least some glioma cell lines reflected those in the primary glioma tissues.

Adult↗