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Biomedical subjects

K Shimada

Publications and source records attributed to K Shimada.

At least 1,135 records · Page 63Linked to original sources
PubMed1989

Immobilized enzyme reactors for detection systems in high-performance liquid chromatography.

The applications of immobilized-enzyme reactors (IMERs) to detection systems in high-performance liquid chromatography (HPLC) have been reviewed. A substrate unresponsive to the detector is enzymatically converted to a highly responsive product. The main analytes detected by this system are various steroids, conjugates of various compounds, acetycholine, choline and amino acids. The repetitive use of a single batch of expensive enzyme has economic advantages. On the other hand, the organic modifier in the mobile phase exerts a considerable influence on the activity and stability of the IMER. Usually the activities of the IMER decrease after two or three months of ordinary use. These problems need to be overcome in the future. HPLC-IMER systems are being used in the field of clinical chemistry, and further applications to other fields are expected to be developed.

Chromatography, High Pressure Liquid↗
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

Sensitive ferrocene reagents for derivatization of amines for high-performance liquid chromatography with electrochemical detection.

Six reagents possessing ferrocene as an electrophore were prepared and evaluated for pre-column derivatization of amino compounds for their determination by high-performance liquid chromatography with electrochemical detection. The utility of these reagents was investigated employing phenethylamine as a model compound. Among these six, N-succinimidyl 3-ferrocenylpropionate was the best with respect to reactivity, stability and electrochemical properties. The developed method was applied to the determination of putrescine formed from ornithine by ornithine decarboxylase.

Amines↗
PubMed1989

cDNA cloning and expression of pig cytosolic aspartate aminotransferase in Escherichia coli: amino-terminal heterogeneity of expressed products and lack of its correlation with enzyme function.

A full-length cDNA encoding the pig cytosolic aspartate aminotransferase (EC 2.6.1.1) (cAspAT) was constructed from two overlapping cDNA clones. One clone (Lm pcAAT-8) isolated from a lambda gt10 pig heart cDNA library contained a 3' untranslated sequence, a poly(A) segment, and a part of the coding region for amino acid positions 127-412. Another clone (Lm pcAAT-107) isolated from a lambda gt10 primer extension library contained the coding region for amino acid positions 1-148 and a 5' untranslated sequence. Rejoining of the cDNA inserts of the two clones and recloning into pUC18 gave rise to a cDNA covering an entire coding sequence for pig cAspAT mRNA. Insertion into pKK223-3 yielded an expression plasmid, ppcAAT200. Escherichia coli JM105 cells transfected with ppcAAT200 overproduced pig cAspAT to an extent of about 3% of the total cellular soluble proteins. The expressed product was indistinguishable from the alpha subform of cAspAT isolated from pig heart in terms of specific activity, absorption spectra, molecular size, crystalline form, and immunological reactivity with anti pig cAspAT antibody. Compared with the amino-terminal sequence (Ala-Pro-Pro-) reported for pig heart cAspAT, the recombinant pig cAspAT showed heterogeneity in the amino-terminal sequence: Ala 1 (26%), Pro2 (54%), and Pro3 (19%). Construction of a mutant cAspAT with deletion of residues 1-3 and its comparison with the wild-type enzyme revealed that loss of the three amino-terminal residues does not affect the catalytic activity and structural integrity of the enzyme.

Amino Acid Sequence↗
PubMed1989

Three cases of Wegener's granulomatosis treated with an antimicrobial agent.

Sulfamethoxazole-trimethoprim, an antimicrobial agent, was used to treat three cases of cytotoxic agent-resistant Wegener's granulomatosis; one case was refractory to a regimen consisting of azathioprine and prednisolone, and in another two cases the therapy was insufficient to control the disease. By the introduction of sulfamethoxazole-trimethoprim, which has an advantage of fewer side effects compared with the conventional agents, into the regimen, the disease condition was markedly improved in all cases within four months. Sulfamethoxazole-trimethoprim is thus considered as one of the most promising drugs to treat, especially, cytotoxic agent-resistant Wegener's granulomatosis. The possible underlying mechanism of the effect of sulfamethoxazole-trimethoprim is also described.

Adult↗
PubMed1989

Morphology of the pterygomandibular raphe in human fetuses and adults.

The pterygomandibular raphe as described in current anatomy textbooks is not supported by actual observations in cadavers. A study was made on 60 adult Caucasian and Negro cadavers (52 right and 58 left sides, giving a total of 110 sides) providing comparison with an earlier study on Japanese specimens. In addition, 50 fetuses (25 mm crown-rump length to term) were examined to determine the arrangement of the raphe prenatally. Variations in the morphology of the raphe region were classified into three types: Type A--only the upper portion of the raphe could be identified and had a broad, triangular shape. Type B--the buccinator and superior pharyngeal constrictor muscles were widely separated by a broad, fascial region. Type C--the raphe was absent with complete continuity of the buccinator and superior pharyngeal constrictor muscles. A prominent, narrow, tendinous band with attachments as described in current textbooks was never found in adults. There was a complete absence of the raphe in 36% of the specimens resulting in continuity of the buccinator and superior pharyngeal constrictor muscles (type C). However, the remaining adult specimens (64%) exhibited some form of a broad, fascial region that either completely (type B, 36%) or partially (type A, 28%) separated the two muscles. All of the fetuses exhibited the type B arrangement exclusively, indicating that changes in the shape of the raphe occur postnatally. The frequency of appearance of the raphe types in adults differs significantly according to race.

Black People↗
PubMed1989

Differential distribution and ultrastructural staining of oxytalan and elastic fibers in the periodontal ligament of Alligator mississippiensis.

We have investigated ultrastructural cytochemical properties of elastic elements in Alligator periodontal ligaments decalcified with EDTA and stained with 1) the tannic acid-uranyl acetate (TA-UA) method for elastin in combination with elastase digestion; 2) the high iron diamine-thiocarbohydrazide-silver proteinate (HID-TCH-SP) method with prior treatment of specimens with either monopersulphate or cupric-sulphite reagent for the localization of disulphide- and/or sulphydryl-containing material (i.e., oxytalan fibers); and 3) HID-TCH-SP alone for sulphated complex carbohydrates. Many microfibrils accumulated to form either large or small bundles. Large bundles having a diameter of 2.50 +/- 1.10 microns (mean +/- SD; n = 50) each showed an apico-occlusal distribution, although small bundles measuring 0.63 +/- 0.13 microns (mean +/- SD; n = 50) in diameter each were exclusively localized in interstitial areas rich in vessels and nerves. The former bundles always lacked TA-UA reactivity and represented oxytalan fibers; the latter bundles frequently contained TA-UA-reactive elastase digestible components and were similar in appearance to immature elastic fibers or elaunin fibers. HID-TCH-SP after oxidation strongly stained both the oxytalan and elastic fiber microfibrils but stained the amorphous elastin very weakly or not all. In nonoxidized specimens, there was no definite HID-TCH-SP staining of microfibrils and the amorphous elastin, although adjacent matrix proteoglycans stained consistently. These results indicate that although there is a marked difference in the distribution and size of oxytalan and elastic fibers in Alligator periodontal ligaments, their associated microfibrils lack stainable sulphate groups but are enriched with disulphide and/or sulphydryl groups, as has been described in mammals.

Alligators and Crocodiles↗
PubMed1989

New development and progression of renal scarring in children with primary VUR.

To study the development of new scars and progression of previous scarring, we analysed 711 children with primary VUR. New scar or progression of previous scarring was observed in 7.3% of the kidneys with reflux. Factors which promote the formation of new scars are high-grade VUR, recurrent UTIs and high-pressure bladder which results in high-pressure reflux. The average age of new scarring was from 7 to 9 years. We emphasize the importance of the follow-up study until the age of 15 years, even after reflux has stopped following surgery.

Adolescent↗
PubMed1989

Loss in transformed cells of cell cycle regulation of expression of a nuclear protein recognized by SLE patient antisera.

The identification of cellular proteins involved in the control of cell proliferation in normal cells is essential for understanding the mechanism underlying growth regulation and cellular transformation. A nuclear protein termed Ki antigen with a relative mobility of 32,000 (Mr 32K) and which is recognized by SLE patient antisera has been identified in cells of human, bovine, and murine origin. Recently, cDNA clones for the bovine and human Ki antigens have been isolated using SLE patient antisera (T. Nikaido, et al., in preparation). The nucleotide sequence predicted a protein of 239 amino acids with a possible nuclear localization signal resembling that identified in SV40 T antigen and other nuclear proteins. Here we show that the expression of Ki antigen is regulated in the normal cell, but not in the transformed cell. Furthermore, in the K-ras temperature-sensitive mutant cell line, ts 371 normal rat kidney (NRK), Ki antigen expression increases several-fold at the permissive temperature relative to the nonpermissive temperature. These results suggest that expression of Ki antigen might be correlated with cellular transformation as well as with cell growth regulation.

Animals↗
PubMed1989

Autonomic nervous reflexes in respiration elicited by mechanical stimulation of the velopharyngeal region in rabbits.

Reflex increases in peak activity of the diaphragm and expiratory pharyngeal muscles were recorded in lightly anesthetized and vagotomized rabbits by gentle mechanical stimulation of the nasal surface of the soft palate and of the posterior wall of the nasopharynx. No noticeable change in diaphragmatic activity was evoked by gentle mechanical stimulation of the oral surface of the soft palate and of the posterior wall of the oropharynx. The present results suggest that afferent signals from mechanoreceptors of the velopharyngeal region may contribute to reflex augmentation of respiration.

Animals↗
PubMed1989

IgG class anti-cardiolipin antibody as a possible marker for evaluating fetal risk in patients with systemic lupus erythematosus.

To identify the correlation between incidence of anti-phospholipid antibodies and fetal prognosis in pregnant SLE patients, we measured the amount of anti-cardiolipin antibody in their sera, using solid-phase enzyme immunoassay (EIA) methods. Findings in the group having poor obstetric results (fetal loss group) and in those with a history of full-term births (live birth group) were compared with regard to other anti-phospholipid antibodies. The incidence of IgG class anti-cardiolipin antibody was 60% in the fetal loss group and 19% in the live birth group, (P less than 0.05). The incidence of the other anti-phospholipid antibodies, including lupus anticoagulant and biological false-positive serological test for syphilis (BFP-STS), did not differ significantly between the two groups. Therefore, the presence of IgG class anti-cardiolipin antibody may prove to be a useful marker for evaluating fetal risk in SLE patients.

Biomarkers↗
PubMed1989

Gonadotropin-stimulated estradiol production in small ovarian follicles of the hen is suppressed by physiological concentrations of prolactin in vitro.

The in vitro effects of physiological levels of prolactin (PRL) on luteinizing hormone (LH)-stimulated estradiol production by four classes of small follicles (super small (SS) less than 1 mm; small white (SW) 1-2 mm; large white (LW) 3-5 mm; and small yellow (SY) 5-10 mm) were compared in laying and out-of-lay (OL) Gifujidori hens. All classes of follicles responded to increasing doses of LH in a dose-dependent manner and the estradiol content of the media increased two to five-fold when 8 ng/ml of ovine LH was included in the incubation media. Ovine PRL (up to 1 micrograms/ml) had no effect on the LH-stimulated rise in media content of estradiol from SW or LW follicles from either the laying or OL hens, whereas the rise in the estradiol content of the media from SS follicles was blocked or reduced by 500 ng/ml PRL in the laying and OL hens, respectively. This suggests that the SS follicles are a target organ for PRL and that PRL may act, in part, at the level of the ovary to reduce estradiol production at the onset of incubation behavior and thus cause ovarian regression.

Animals↗
PubMed1989

Detection of human immunodeficiency virus (HIV) in cultures of lymphocytes from HIV-seropositive persons with special reference to an enzyme immunoassay.

Three different assay systems for monitoring the production of human immunodeficiency virus (HIV) in infected cells were compared. These were (1) a reverse transcriptase assay (RTA), (2) an indirect immunofluorescence assay (IFA), and (3) an enzyme immunoassay (EIA) for detecting HIV antigen in vitro. MOLT-4 subclone 1 cells were infected with serial dilutions of the HTLV-IIIB strain of HIV. Six days after infection, production of HIV was examined by the three methods. EIA was most sensitive showing 64-fold higher sensitivity than RTA, which in turn was fourfold more sensitive than IFA. We applied EIA for detecting HIV in the lymphocyte cultures derived from 18 HIV-seropositive persons. By means of the three systems HIV was isolated from lymphocyte cultures derived from one of nine (11%) asymptomatic persons and from five of nine (56%) symptomatic patients. Interestingly, it was noticed that four samples of lymphocytes did not allow the isolation of HIV but gave positive results by EIA only. Thus, the detection rate of HIV was increased by the application of EIA, to three of nine (33%) persons in the asymptomatic group and to seven of nine (78%) patients in the symptomatic group. Possible use of this assay system for following the development of acquired immunodeficiency syndrome is discussed.

Cells, Cultured↗
PubMed1989

Endobronchial non-Hodgkin's lymphoma.

A 64-year-old man with non-Hodgkin's lymphoma suffered a complete collapse of the left upper lobe of the lung. Fibreoptic bronchoscopy demonstrated a large number of distinct polypoid tumours of the lymphoma in the trachea and bilateral sub-segmental bronchi. The left upper lobe bronchus was completely occluded by the tumours, which responded to the combination chemotherapy against the lymphoma. This report presents the seventh case of non-Hodgkin's lymphoma with multiple endobronchial tumours.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

Application of inclusion chromatography to the determination of in vitro metabolites of estriol.

The application of inclusion chromatography with beta-cyclodextrin as a mobile phase additive in high-performance liquid chromatography to the determination of in vitro metabolites of estriol is reported. Compared to conventional methods, the inclusion chromatography gives much more satisfactory separation of isomeric estriol derivatives in a short time. Species difference (rat and guinea pig liver homogenates) is observed in the glucuronidation of estriol. The hydroxylation of estriol with rat liver homogenate occurs preferentially at the 2-position. Methylation of this product with catechol-O-methyl transferase in rat liver gives almost equal amounts of 2- and 3-methyl ethers. In contrast, 4-hydroxyestriol gives 4-methyl ether as a main product.

Animals↗