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Biomedical subjects

T Nishi

Publications and source records attributed to T Nishi.

At least 235 records · Page 13Linked to original sources
PubMed1991

Prenatal diagnosis of autosomal recessive polycystic kidney disease by ultrasonography and magnetic resonance imaging.

Autosomal recessive polycystic kidney disease is a relatively rare congenital disease affecting the kidneys and liver. We noticed the kidney abnormality at 22 weeks gestation and observed the patient till the delivery at 36 weeks of gestation. The ultrasonographic features consisted of bilaterally enlarged hyperechogenic kidneys, oligohydramnios, lack of distention and difficulty in identifying the fetal urinary bladder. The serial sonographic features of the kidneys changed as pregnancy progressed. The kidney cysts gradually changed in size, shape and renal texture, but the umbilical velocimetry and the kidney circumference/abdominal circumference ratio did not change. Magnetic resonance imaging also showed similar characteristic features as observed by ultrasonography.

Adult↗
PubMed1991

[Nuclear DNA content in breast cancer in relation to postoperative recurrence].

Nuclear DNA content in breast cancer patients who underwent extended radical mastectomy was investigated to evaluate its possible relation to postoperative recurrence. The most frequent site of the first recurrence in diploid type (D type) cases was the bone and the frequency was significantly higher than that in non-diploid type (N type) cases. On the other hand, the ploidy pattern in all cases associated with local or local lymph node recurrence was N type and the lung was the next frequent site of recurrence in N type case. The frequency of over 4c cells was the highest in the cases of local or local lymph node recurrence being significantly higher than in all cases of distant recurrence or of the bone recurrence. The cumulative disease-free survival rate in patients with D type breast cancer was significantly higher than that in patients with N type. These results suggest that nuclear DNA content provides important information for deciding therapy and the schedule of postoperative follow-up study based on the mode of recurrence.

Breast Neoplasms↗
PubMed1991

Differential expression of two types of the neurofibromatosis type 1 (NF1) gene transcripts related to neuronal differentiation.

A 360 residue region encoded by the neurofibromatosis type 1 (NF1) gene shows significant homology to the catalytic domains of both mammalian GTPase-activating proteins (GAP) and yeast IRA proteins. This GAP-related domain of the NF1 gene (NF1-GRD), like the GAP and IRA protein, has been reported to mediate hydrolysis of Ras-bound GTP to GDP, resulting in inactivation of Ras protein. In the present study, we identified two different types of NF1-GRD cDNA. One (type I) is identical to the previously reported sequence, and the other (type II) contained an additional 63 bp insertion that encodes for a region of 21 amino acids in the center of the NF1-GRD molecule. Alternative splicing is the most likely mechanism by which these two types of transcripts arise. Our observations reveal that the type I transcript is predominantly expressed in undifferentiated cells, whereas the type II transcript predominates in differentiated cells. Furthermore, the expression pattern of type I and type II NF1-GRD mRNA immediately changed in SH-SY5Y neuroblastoma cells when neuronal differentiation programs were induced by retinoic acid treatment. We propose that the differential expression of type I and type II NF1-GRD transcripts might be an 'on/off' switch that regulates the catalytic activity of the NF1 gene product, which plays an important role in the regulation of neuronal differentiation.

Amino Acid Sequence↗
PubMed1990

[Prognostic significance of nuclear DNA content in breast cancer].

The relationship between nuclear DNA content determined by cytofluorometry in the primary focus of breast cancer and the survival rate was analyzed to clarify the prognostic significance of nuclear DNA content in breast cancer. The relationships of the ploidy pattern and the frequency of polyploid cells (4c or above) with the survival rate were studied in patients who underwent extended radical mastectomy and were comparable in the clinical stage and other prognostic factors. The survival rate was significantly lower in those of the non-diploid type showing no prominent peak at 2c or those in whom the frequency of polyploid cells was more than 30% than in those of the diploid type with a prominent peak at 2c or those showing few polyploid cells, even when the disease stage (Stage II by TNM classification and stage III by Tnm classification), histological lymph node metastasis (n (+), n1 beta), and histological type (papillotubular carcinoma, scirrhous carcinoma) were identical. From these findings, nuclear DNA content is considered to be a parameter of the malignancy of breast cancer and to have clinical significance as an important prognostic factor.

Breast Neoplasms↗
PubMed1990

The light-suppressible K+ conductance and evaluation of internal messenger candidates in the molluscan extraocular photoreceptor.

A photoreceptor potential produced by a decrease in membrane conductance was not thought to occur in any invertebrate photoreceptors. However, we have found that the molluscan extraocular photoreceptor, A-P-1 responds to light with a depolarizing receptor potential due to a decrease in K+ conductance, so that the photoresponse associated with a decrease in membrane conductance is not unique to the vertebrate photoreceptor. The properties that the light-suppressible K+ conductance is time- and voltage-dependent are explained by comparison with those of the single channel conductance obtained in patch-clamp of both vertebrate and invertebrate photoreceptors. The noise analysis of the light-induced current suggest that this macroscopic light-suppressible conductance consists of channels. It is concluded that the light-suppressible K+ conductance is mediated by hydrolysis of cGMP which reduces internal cGMP, in agreement with the cGMP hypothesis of vertebrate phototransduction and that the hydrolysis may be modified by IP3.

Animals↗
PubMed1990

Surgical treatment of reflux stricture of the esophagus.

Ten children, aged 7 months to 15 years, with peptic esophageal stricture, were treated surgically. In four of the children, the stricture had occurred after esophageal anastomosis. Peptic stricture was diagnosed by esophagography, pH monitoring, manometry, and esophagoscopy. Barrett's esophagus was found in two children. Nine children underwent transabdominal Nissen fundoplication initially. In the first child of this series, a tight anastomotic stricture had been excised 2 weeks before fundoplication. Seven children became complaint-free within 2 or 3 months after fundoplication without any dilatation, and two children with anastomotic stricture improved after 1 or 2 postoperative dilatations. The condition of one boy, with a 6-year history of tight stricture, did not improve with repeat Nissen and subsequent dilatations. Histological examination showed proliferation of smooth muscle cells in the submucosa. A conservative surgical approach is effective for the management of peptic esophageal stricture in children, and direct surgical intervention for stricture should be attempted only in cases of stricture resistant to antireflux surgery with a long history of reflux.

Adolescent↗
PubMed1990

Syntheses and biological activities of renin inhibitors containing statine analogues.

Syntheses and biological activities of dipeptide renin inhibitors that contain statine analogues are described. The key steps of the synthetic approach to dipeptide renin inhibitors are the asymmetric synthesis of 2(R)-substituted-3-aminocarbonylpropionic acids and the diastereoselective syntheses of (3S,4S)-statine analogues. These inhibitors (2,14-40) inhibited human renin in the 3-140 nM range. Inhibitor ES 6864 (2) was found to be a highly potent inhibitor of human renin (IC50: 4.6 x 10(-9) M) and showed high enzyme specificity. Oral administration of ES 6864 at 3 mg/kg to conscious, sodium-depleted marmosets inhibited plasma renin activity (PRA) more than 80% after 1 h.

Amino Acids↗
PubMed1990

Effect of fructose on glycogen synthesis in the perfused rat liver.

The effect of fructose on glycogen synthesis was examined in the perfused liver of starved rats. With increasing fructose concentration in the perfusate, glycogen synthesis and the % a form of glycogen synthase increased to a maximum at 2 mM and then decreased, progressively. The glucose 6-P level increased with the increase in fructose concentration. On the other hand, the ATP content was unchanged at a concentration of 2 mM or less and decreased at 3 mM or more. We also showed that the stimulation of glycogen synthesis by fructose at a concentration of 2 mM or less was due to activation of glycogen synthase by accumulated glucose 6-P and that ATP depletion at a concentration of 3 mM or more caused an increase in phosphorylase a and a decrease in glycogen synthase activity even in the presence of a high concentration of glucose 6-P.

Adenosine Triphosphate↗
PubMed1990

[Treatment of adult T-cell leukemia with intravenous administration of IFN-gamma-immunohistochemical studies of infiltrating cells in cutaneous lesions].

Three cases of adult T-cell leukemia (ATL) with cutaneous lesions of disseminated papules or nodules were treated with recombinant human interferon-gamma (IFN-gamma) by intravenous administration. Clinical stage of each case was different, i.e., 1) preleukemic state of ATL (pre-ATL), 2) chronic-type ATL, and 3) crisis-type ATL. We evaluated clinical efficacy of IFN-gamma, and performed immunohistochemical analysis of biopsy specimens derived from cutaneous lesions of the patients both before and during treatment. The case of pre-ATL achieved a complete remission of cutaneous lesions for 18 months. The other cases also obtained clinical responses with a shorter duration, but relapsed while they are still on IFN-gamma therapy. The cutaneous lesions reduced in size during the therapy associated with a decrease in the ratio of Leu3a + 3b (CD4)+ cells in all three cases. After the therapy, Leu7 (HNK-1)+ cells increased in all cases, and LeuM5 (CD11)+ cells did in two. These results suggested that IFN-gamma enhanced tumor immunity although its clinical effect was less clear. Only in the cutaneous lesions of pre-ATL case an increased number of LeuM5+ cells, probably monocyte-macrophage series in host defence, were seen before the therapy. And IFN-gamma was useful for this case after all.

Female↗
PubMed1990

[Estimating organ doses of dental students in dental radiographic exercises].

To estimate doses absorbed in organs of dental students in the exercises of dental radiography, we measured the average organ doses of the dental radiographic examinations and sent out questionnaires about the radiographic exposure of the dental students. We selected five organs in the head and neck regions: lens of the eye, parotid gland, submaxillary gland, thyroid and pituitary fossa. The dose determinations were made for the full mouth intra-oral radiography with 10 films, and panoramic radiography and cephalometric radiography. Doses for all organs, except for the parotid gland, were widely distributed with one peak. The highest average dose per dental student was about 5000 microGy for the parotid gland, about 2900 microGy for the submaxillary gland, about 900 microGy for the lens of the eye, about 480 microGy for the thyroid and about 140 microGy for the pituitary fossa. Dose limits for dental students in such exercises have not been yet established. But the organ doses, especially for the parotid gland, appear very high. To reduce exposure in the exercises and to protect the dental students from excess exposure, we need to reconsider the study of dental radiographic techniques.

Adult↗
PubMed1990

[Statistical analysis of nuclear medicine in the Higashi Nippon Gakuen University Dental Hospital].

The number of radionuclide in vivo tests carried out at the Higashi Nippon Gakuen University Dental Hospital was statistically analyzed and discussed. The subjects were all patients admitted to the Division of Nuclear Medicine during the seven years between 1981 and 1989. The total number of the patients included those introduced through medical facilities in Toubetsu-cho and others. The results of this analysis were as follows: 1) The proportion of the first time patients admitted to the Higashi Nippon Gakuen University Dental Hospital was only 11 percent of all patients. 2) Cases of radionuclide in vivo tests at the Higashi Nippon Gakuen University Dental Hospital decreased in number, annually. However the proportion of tumor scintigraphy and bone scintigraphy increased gradually.

Female↗
PubMed1989

A light-induced decrease of cyclic GMP is involved in the photoresponse of molluscan extraocular photoreceptors.

The depolarizing photoreceptor potential in the molluscan extraocular photoreceptor, A-P-1, results from the light-induced suppression of specific K+ currents. An application of cGMP or IBMX (inhibitor of phosphodiesterase) to A-P-1-evoked light-suppressed currents, similar to the above specific K+ currents. Thus, the light-induced decrease of cGMP levels in A-P-1 may be responsible for the photoreceptor potential, like vertebrate phototransductions.

1-Methyl-3-isobutylxanthine↗
PubMed1989

Import and processing of precursor to mitochondrial aspartate aminotransferase. Structure-function relationships of the presequence.

The precursor protein of pig mitochondrial aspartate aminotransferase (pre-mAspAT) contains a 29-residue presequence (Joh, T., Nomiyama, H., Maeda, S., Shimada, K., and Morino, Y. (1985) Proc. Natl. Acad. Sci. U. S. A. 82, 1-5). Pre-mAspAT produced in an in vitro transcription and translation system was avidly imported into pig and rat liver mitochondria to be processed to the mature form of the enzyme. The pre-mAspAT was also processed to the mature form upon incubation with mitochondrial extracts. We synthesized precursor proteins with alterations within the presequence and compared quantitatively the effects of these mutations on the rates of both import and processing. Single and multiple substitutions of four basic residues with neutral amino acids at positions 5, 8, 18, and 28 showed that each residue contributes differentially to import and processing. Substitutions of His5 and Arg8 with glycines abolished the import activity but did not appreciably affect the rate of processing. Substitution of Arg28 with leucine at the position adjacent to the cleavage site seriously impaired the processing without appreciably affecting the rate of import. Analysis of deletions revealed that the amino-terminal region from position 2 to 8 was essential for both the import and processing. Thus the positive charges in the amino-terminal region are critical for import while the amino-terminal peptide segment and the cleavage site region appear to be requisite for recognition by a processing protease.

Amino Acid Sequence↗
PubMed1989

Mutagenesis of human granulocyte colony stimulating factor.

To define the structure-function relationship, we have made a number of mutants of human granulocyte colony-stimulating factor (hG-CSF) by in vitro mutagenesis. The results indicate that most of the mutations located in the internal and C-terminal regions of the molecule abolished the activity, whereas the mutants without N-terminal 4, 5, 7, or 11 amino acids retained the activity. N-terminal amino acids were also altered by cassette mutagenesis using a synthetic oligonucleotide mixture. Among them, KW2228, in which Thr-1, Leu-3, Gly-4, Pro-5 and Cys-17 were respectively substituted with Ala, Thr, Tyr, Arg and Ser, showed more potent granulopoietic activity than that of intact hG-CSF both in vitro and in vivo.

Amino Acid Sequence↗
PubMed1989

The effect of fructose on the cellular content of adenine nucleotides in the perfused rat liver.

In order to evaluate the validity of using fructose in total parenteral nutrition, the mechanism of the resultant decrease in hepatic ATP content on fructose loading was examined using perfused rat livers. The ATP content of the livers perfused with fructose at a concentration of 2 mM or less, was about 2.8 mumol/g liver. Perfusion with 3 mM and 5 mM fructose decreased the ATP level to 1.65 and 1.50 mumol/g liver, respectively. Transient suppression of respiration occurred after the liver was perfused with fructose at a concentration of 3 mM or more, but not after 2 mM or less. Perfusion of the liver with fructose caused an accumulation of fructose 1-phosphate and a decrease in Pi. At higher concentrations of fructose, the accumulation of fructose 1-phosphate and the depletion of Pi were greater. The Pi depletion, caused by the accumulation of fructose 1-phosphate, suppressed O2 consumption and subsequently decreased the hepatic ATP content. A stoichiometric relationship was found between the total loss of adenine nucleotides in the liver and the amount of purine catabolites in the perfusate. After the administration of fructose at a concentration of 2 mM or less, however, the amount of remaining intracellular Pi was sufficient to maintain respiration and no decrease in the hepatic ATP content was observed.

Adenine Nucleotides↗