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Biomedical subjects

S Nagasaki

Publications and source records attributed to S Nagasaki.

At least 37 records · Page 2Linked to original sources
PubMed1990

Stereospecific abstraction of epsilon-pro-R-hydrogen of L-lysine by L-lysine epsilon-dehydrogenase from Agrobacterium tumefaciens.

The stereochemical aspects of the L-lysine epsilon-dehydrogenase reaction were examined with (6R)-L-[6-3H]lysine and (6S)-DL-[6-3H]lysine. When (6S)-DL-[6-3H]lysine was used as a substrate, the tritium was found in the product, delta 1-piperideine-6-carboxylate. In contrast, the radioactivity from (6R)-L-[6-3H]lysine was not retained in the product. Thus, the pro-R hydrogen at the prochiral C-6 carbon of L-lysine is specifically abstracted by the enzyme: the enzyme behaves stereochemically as an amino acid D-dehydrogenase.

Amino Acid Oxidoreductases↗
PubMed1990

Ruptured amebic liver abscess.

We treated two patients with a ruptured amebic liver abscess. The diagnosis was made at a relatively early stage and treatment was successful for one patient, but an accurate diagnosis of liver abscess was not made and invasive extraintestinal amebiasis led to multiple organ failure and to death for the other. Neither patient had been outside of Japan, and both were heterosexual. The origins of Entamoeba histolytica infection could not be determined. Though the mortality rate is high in cases of ruptured amebic liver abscess, appropriate management can lead to a good prognosis.

Adult↗
PubMed1990

Selective determination of L-lysine with L-lysine epsilon-dehydrogenase.

Simple and sensitive spectrophotometric methods were developed for the selective determination of L-lysine. The assay methods were based on the spectrophotometric determination of NADH formed in the reaction catalyzed by L-lysine epsilon-dehydrogenase (Procedure A) or the formazan produced on coupling of the dehydrogenase reaction with the reduction of a tetrazolium salt (Procedure B). Procedure B was applicable to the direct determination of L-lysine in rabbit serum.

Amino Acid Oxidoreductases↗
PubMed1990

Leucine dehydrogenase from Corynebacterium pseudodiphtheriticum: purification and characterization.

Leucine dehydrogenase [EC 1.4.1.9] was purified to homogeneity from Corynebacterium pseudodiphtheriticum ICR 2210. The enzyme consisted of a single polypeptide with a molecular weight of about 34,000. Stepwise Edman degradation provided the N-terminal sequence of the first 24 amino acids, and carboxypeptidase Y digestion provided the C-terminal sequence of the last 2 amino acids. Although the enzyme catalyzed the reversible deamination of various branched-chain L-amino acids, L-valine was the best substrate for oxidative deamination at pH 10.9 and the saturated concentration. The enzyme, however, had higher reactivity for L-leucine, and the kcat/Km value for L-leucine was higher than that for L-valine. The enzyme required NAD+ as a natural coenzyme. The NAD+ analogs 3-acetylpyridine-NAD+ and deamino-NAD+ were much better coenzymes than NAD+. The enzyme activity was significantly reduced by sulfhydryl reagents and pyridoxal 5'-phosphate. D-Enantiomers of the substrate amino acids competitively inhibited the oxidation of L-valine.

Amino Acid Oxidoreductases↗
PubMed1990

Cloning and expression of endo-beta-1,3-glucanase gene from Flavobacterium dormitator in Escherichia coli and characterization of the gene product.

The beta-1,3-glucanase (1,3-beta-D-glucan glucanohydrolase, EC 3.2.1.6) gene from Flavobacterium dormitator var. glucanolyticae was cloned into Escherichia coli C600 with a vector plasmid, pBR322. The E. coli cells carrying a recombinant plasmid, pKU beta G1 (8.2 kb), showed a high beta-1,3-glucanase activity and a lytic activity on viable yeast cells. These activities were found in the periplasmic space of E. coli clone cells. Southern hybridization analysis showed that the cloned gene was derived from F. dormitator chromosomal DNA. The gene products were purified from the periplasmic fraction of E. coli by ammonium sulfate fractionation and ion-exchange chromatography. The purified enzymes were demonstrated to be identical with a lytic endo-beta-1,3-glucanase II and a nonlytic endo-beta-1,3-glucanase I from F. dormitator from their enzymological and immunological properties. In the E. coli cells, endo-beta-1,3-glucanase I was also formed by a proteolytic digestion of endo-beta-1,3-glucanase II during the cultivation as in F. dormitator. Thus, the only endo-beta-1,3-glucanase II was coded for in the cloned gene.

Cloning, Molecular↗
PubMed1990

Recurrence in early gastric cancer.

In a retrospective study of 503 cases of early gastric cancer, 17 of the patients had died of a recurrence of the gastric cancer and 72 had died of unrelated causes. The cumulative recurrence mortality rates were 2.2% at 9 years for mucosal cancer and 8.4% at 8 years for submucosal cancer. The recurrence patterns of early gastric cancer were hematogenic metastasis to the liver, lung, or bone (nine cases), recurrence from lymph nodes (three cases), and recurrence in the residual stomach (five cases). Submucosal cancers with a macroscopically elevated appearance, lymph node metastasis, and evidence of vessel invasion were the high-risk cancers for hematogenic recurrence, and adjuvant chemotherapy should be prescribed. Two cases of lymph node recurrence were attributed to inadequacy of lymph node dissection. Because metastasis to the group 2 lymph nodes was noted in 1.5% of cases of early gastric cancer and a macroscopic diagnosis of nodal status was inaccurate, complete dissection should be performed regardless of identification of metastasis. Five cases of recurrence in the residual stomach were attributed to overlooked lesions of multiple carcinoma and were detected at an advanced stage. Careful and regular postoperative follow-up is required to detect these recurrences at an early stage.

Blood Vessels↗
PubMed1989

[Definition of the adaptation of endoscopic surgery for early gastric cancer. Special examination on the relationship between the histological differentiation of the intramucosal gastric cancer and the lymph node metastasis].

Out of five hundred and nineteen surgically resected lesions which were histologically shown to be intramucosal gastric cancer, 247 were well differentiated, 98 were moderately differentiated, and 176 were poorly differentiated lesions. The incidence of lymph node metastasis in the 247 well differentiated, 98 moderately differentiated, and 176 poorly differentiated intramucosal adenocarcinomas were 0.8% (= 2/247), 2.1% (= 2/98), and 8% (14/176), respectively. The cumulative survival rate of 5 years after gastrectomy was 94.2% for the 247 well, 93.3% for the 98 moderately, and 93.7% for the 176 poorly differentiated adenocarcinomas. A pathological study on the atypism of the gland of the cancer and the condition of the proprial space under the cancer cells was conducted on 100 lesions of well differentiated adenocarcinomas in order to define the criteria of non-surgical endoscopic removal resection for early gastric cancer. Out of the 100 lesions mentioned above, there were only two well differentiated adenocarcinomas with lymph node metastasis in which the boundary between the epithelium of the cancer and the proprial space under the cancer was very unclear and the interstitial space in the propria under the cancer was very small. On the other hand, we have resected 73 intramucosal gastric cancers using the endoscopic surgical method called strip biopsy since 1984, and have followed up these cases. The cancers resected by strip biopsy, and were histologically intramucosal well differentiated adenocarcinomas shown to have a moderately maintained interstitial space under the cancer cells. And, up to the present, there has been no incidence of recurrence after strip biopsy for the 73 lesions mentioned above. According to these results, we have defined the criterion for early gastric cancer endoscopic surgery, as follows. Intramucosal cancer which is shown to be well differentiated adenocarcinoma with a moderately maintained interstitial space under the cancer cells is considered to be sufficient for non-surgical endoscopic resection.

Aged↗
PubMed1989

Thermostable alanine dehydrogenase of Bacillus sp. DSM730: gene cloning, purification, and characterization.

We have cloned the thermostable alanine dehydrogenase (EC 1.4.1.1) gene from a thermophile, Bacillus sp. DSM730, into Escherichia coli C600 with a vector plasmid, pBR322. The enzyme was overproduced by the transformed cells, and purified to homogeneity with a yield of 69% by heat treatment and another step. The enzyme has a molecular weight of about 250,000 and consists of 6 subunits identical in molecular weight (43,000). It is not inactivated by heat treatment at 75 degrees C for 60 min, or incubation in the pH range of 5.5-10.5 at 55 degrees C for 10 min. The enzyme ctalyzes the oxidative deamination of L-serine in addition to L-alanine. The oxo analogue of serine is as reactive as pyruvate. Thus, the enzyme differs markedly from alanine dehydrogenases so far studied.

Alanine Dehydrogenase↗
PubMed1989

Properties of L-lysine epsilon-dehydrogenase from Agrobacterium tumefaciens.

Lysine epsilon-dehydrogenase, which has been purified to homogeneity from the extract of Agrobacterium tumefaciens ICR 1600, had a molecular weight of approximately 78,000 and consisted of two subunits identical in molecular weight (about 39,000). The enzyme showed a high substrate specificity. In addition to L-lysine, S-(beta-aminoethyl)-L-cysteine was deaminated by the enzyme, but to a far lesser extent. NAD+ and some NAD+ analogs (deamino-NAD+ and 3-acetylpyridine-NAD+) served as a cofactor. The pH optimum was at about 9.7 for the deamination of L-lysine. Although the NAD+ saturation curve was hyperbolic, a sigmoid saturation curve for L-lysine was obtained with the diluted enzyme solution, in which the dimeric enzyme was predominant. The reversible association of the enzyme to the tetramer was induced either by increasing the enzyme concentration or by addition of L-lysine. The preincubation of the enzyme with 5 mM L-lysine resulted in a 2-fold increase in the activity and gave a hyperbolic saturation curve for L-lysine. Upon modification of SH groups of the enzyme with DTNB, neither the interconversion between the dimer and the tetramer nor the activation by L-lysine occurred. These results indicated that the dimeric enzyme was activated by L-lysine and the activation resulted from the association of two dimeric enzymes to form a tetramer.

Amino Acids↗
PubMed1989

Activation of L-lysine epsilon-dehydrogenase from Agrobacterium tumefaciens by several amino acids and monocarboxylates.

The activation of lysine epsilon-dehydrogenase [EC 1.4.1.] by L-lysine was dependent on lysine concentration and was accompanied by association of the dimeric enzymes to a tetramer. The lysine concentration required for the half-maximal activation was 0.28 mM, which was lower than the Km value for L-lysine. In addition to L-lysine, several compounds, which were neither substrates nor inhibitors, activated the enzyme. The compounds which activated the enzyme have common structural characteristics: they have both a carboxyl group and a hydrophobic side chain. These activators also induced the association of the enzyme. The activation of the enzyme occurred well over the pH range 5.0 to 7.5, and the maximal activation was obtained by preincubation for 5 min at 30 degrees C and pH 7.4, when 5 mM L-lysine or 6-aminocaproate was used as an activator. NADH binding experiments indicated that about 2 mol of NADH bind to 1 mol of the tetrameric enzyme: the dimeric enzyme has one catalytic site. Binding experiments with n-[1-14C]heptanoate and L-[U-14C]lysine showed that approximately 2 mol of ligands bind to 1 mol of the dimeric enzyme and L-lysine could not bind to the catalytic site of the enzyme in the absence of NAD+. These results indicate the presence of one catalytic site and two activator binding binding sites in the dimeric enzyme.

Amino Acid Oxidoreductases↗
PubMed1989

Purification and characterization of a dimeric phenylalanine dehydrogenase from Rhodococcus maris K-18.

NAD+-dependent phenylalanine dehydrogenase (EC 1.4.1.) was purified to homogeneity from a crude extract of Rhodococcus maris K-18 isolated from soil. The enzyme had a molecular mass of about 70,000 daltons and consisted of two identical subunits. The enzyme catalyzed the oxidative deamination of L-phenylalanine and several other L-amino acids and the reductive amination of phenylpyruvate and p-hydroxyphenylpyruvate. The enzyme required NAD+ as a natural coenzyme. The NAD+ analog 3-acetylpyridine-NAD+ showed much greater coenzyme activity than did NAD+. D-Phenylalanine, D-tyrosine, and phenylethylamine inhibited the oxidative deamination of L-phenylalanine. The enzyme reaction was inhibited by p-chloromercuribenzoate and HgCl2. Initial-velocity and product inhibition studies showed that the reductive amination proceeded through a sequential ordered ternary-binary mechanism. NADH bound first to the enzyme, followed by phenylpyruvate and then ammonia, and the products were released in the order L-phenylalanine and NAD+. The Michaelis constants were as follows: L-phenylalanine, 3.8 mM; NAD+, 0.25 mM; NADH, 43 microM; phenylpyruvate, 0.50 mM; and ammonia, 70 mM.

Amino Acid Oxidoreductases↗
PubMed1989

[Difference in the postnatal development of the layer structures in the phylogenetically different cat cerebellar cortices].

Although it has long been accepted that the structure of the cerebellar cortex is the same all over its areas, some of the recent studies indicated that there are regional differences in the time course of development of the cortical layer structures as well as in its cytoarchitecture. The cerebellum consists of 3 phylogenetically different areas; archi-, paleo- and neocerebellum, which deals with vestibular, spinal cord and cerebral cortical activities respectively. The development of the structures of cerebellar cortex occurs mostly after birth in the altrical animals, and the control of the posture and movement takes place faster in the trunk than in the extremities in such animals. It could be expected that the postnatal development occurs faster in the phylogenetically older parts than in the newer ones. To elucidate the above mentioned assumption, post-natal development of the cerebellar cortical structures was studied, cytoarchitectonically and cell morphologically, using cats from birth to the adult state. The external granular layer increased in thickness from birth to 2-9th postnatal days, then decreased gradually, and almost disappeared by the 63rd postnatal day. While the molecular and the internal granular layers increased in thickness gradually after birth, and reached the adult level by the 63rd postnatal day. Cytoarchitectonically, postnatal development took place faster in the archicerebellum, next in the paleocerebellum and slowest in the neocerebellum. Silver impregnation study showed the first dendritic arborization of the Purkinje cell appeared on the 7th postnatal day in the arch- and paleocerebellum, while the same phenomenon was observed on the 14th postnatal day in the neocerebellum. The above observations confirmed our assumption that phylogenetically older parts of the cerebellar cortex have faster postnatal development than the newer ones. This is in agreement with the fact that the function of the neuronal activity in these phylogenetically older parts occurs earlier than in the newer parts.

Animals↗
PubMed1986

[Two cases of recurrent gastrointestinal carcinoma treated with long-term THP].

Two patients with recurrent gastrointestinal carcinoma were treated with THP. Partial response was recognized in the local recurrent tumor of one patient and in liver metastasis of a second patient. THP was administered every three weeks at a dose of 60 mg per total body weight intravenously. The total dose of THP achieved was 720 mg in the first patient and 920 mg in the second. Despite the high dosage, neither cardiotoxicity nor alopecia was observed. These results suggest that the administration of THP may be efficacious and safe in the management of patients with recurrent gastrointestinal carcinoma.

Adenocarcinoma↗
PubMed1985

[Phase II study of (2''R)-4'-0-tetrahydropyranyladriamycin (THP) in gastrointestinal cancer].

A phase II study of a new anthracycline, (2''R)-4'-0-tetrahydropyranyladriamycin (THP) was performed on 37 patients with gastrointestinal cancer in 6 co-operative study institutions. Twenty-five patients out of 37 were evaluable for response according to the Koyama-Saito's criteria. THP was administered weekly at doses of 10 to 30 mg/body or every 3 to 4 weeks at doses of 40 to 60 mg/body intravenously. Of the 14 patients with gastric cancer, we obtained one complete response and 3 partial responses (response rate 28.6%), and of the 6 patients with rectal cancer, we obtained one partial response (16.7%). Leukopenia of less than 3 X 10(3)/mm3 and erythrocytopenia of less than 300 X 10(4)/mm3 were seen in 48% and 26% of cases. Neither cardiotoxicity nor hair loss were seen. These results suggest that THP is useful in the treatment of patients with gastrointestinal cancer.

Adult↗
PubMed1982

Occurrence of L-lysine epsilon-dehydrogenase in Agrobacterium tumefaciens.

A novel amino acid dehydrogenase catalyzing the oxidative deamination of the epsilon-amino group of l-lysine was found in the crude extract of Agrobacterium tumefaciens ICR 1660. The enzyme required NAD(+) and was specific for l-lysine. The enzyme was optimally active at about pH 9.7.

Amino Acid Oxidoreductases↗