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Biomedical subjects

M Shin

Publications and source records attributed to M Shin.

At least 37 records · Page 2Linked to original sources
PubMed1997

Thiocyanato and Iodo Complexation of Cadmium(II) Ions in Micellar Solutions of a Nonionic Surfactant Triton X-100

Complexation of the cadmium(II) ion with thiocyanate and iodide ions have been studied by precise titration calorimetry in micellar solutions of a nonionic surfactant Triton X-100 containing 0.4 mol dm-3 NaClO4 as a constant ionic medium at 298 K. With regard to the Cd(II)-SCN- system, the formation of [Cd(NCS)]+ and [Cd(NCS)(SCN)] in aqueous solution and [Cd(NCN)2(SCN)]- in micelles was established, though the complexation in micelles is not extensive. With the Cd(II)-I- system, the formation of [CdI]+, [CdI3]-, and [CdI4]2- was established in aqueous solution together with the formation of [CdI2], [CdI3]-, and [CdI4]2- in micelles. It is revealed that the complexation in micelles is accompanied by relatively large and negative enthalpies, which is ascribed to the enthalpies of transfer of [CdI3]- and [CdI4]2- from aqueous solution to micelles. This suggests that a hydrophobic complex with no capacity to form strong hydrogen bonds in water is favored in micelles.

Journal Article↗
PubMed1997

[Examination of scanning technique for lung cancer screening with helical CT].

As a new application of helical CT scanning we evaluated the parameters for lung cancer screening with an extremely low doses and large helical pitch. On the phantom studies, the image quality obtained with the low dose parameter was not inferior to that of the usual screening technique but artifacts were increased with the large helical pitch. A scanning technique using 120 kv, 40-60mA, 10mmth, 20mm/ sec, and a reconstruction pitch of 2 was used for lung cancer screening (screening parameters) (50 cases), and comparison was made between the detectability of the screening parameters and the routine parameters (120 kv, 200mA, 10mmth, 10-13mm/sec, and a reconstruction pitch of 1-1.3). Detectability with the screening parameters was as follows: nodular lesions (< 5mm in size: 76%. 5-10mm: 90-93% 10mm < 100%), linear lesions: 94-95%, infiltrations: 93-100%. There were no false negative lesions, when the reconstruction pitch of the screening parameters was changed from 1 to 0.25. In conclusion, reconstruction pitch had the most influence on lesion detectability.

Adult↗
PubMed1996

Mice with disrupted GM2/GD2 synthase gene lack complex gangliosides but exhibit only subtle defects in their nervous system.

Gangliosides, sialic acid-containing glycosphingolipids, are abundant in the vertebrate (mammalian) nervous system. Their composition is spatially and developmentally regulated, and gangliosides have been widely believed to lay essential roles in establishment of the nervous system, especially in neuritogenesis and synaptogenesis. However, this has never been tested directly. Here we report the generation of mice with a disrupted beta 1,4-N-acetylgalactosaminyltransferase (GM2/GD2 synthase; EC 2.4.1.92) gene. The mice lacked all complex gangliosides. Nevertheless, they did not show any major histological defects in their nervous systems or in gross behavior. Just a slight reduction in the neural conduction velocity from the tibial nerve to the somatosensory cortex, but not to the lumbar spine, was detected. These findings suggest that complex gangliosides are required in neuronal functions but not in the morphogenesis and organogenesis of the brain. The higher levels of GM3 and GD3 expressed in the brains of these mutant mice may be able to compensate for the lack of complex gangliosides.

Animals↗
PubMed1996

NAD+ biosynthesis and metabolic fluxes of tryptophan in hepatocytes isolated from rats fed a clofibrate-containing diet.

Hepatocytes were isolated from rats fed a diet with or without 0.25% clofibrate, and NAD+ synthesis by the hepatocytes was determined using either [carboxyl-14C]nicotinic acid or [5-3H]tryptophan. NAD+ and total pyridine nucleotides synthesized from [14C]nicotinic acid by the clofibrate-treated cells were not significantly different from those synthesized by the control cells when expressed on the basis of nanomoles per hour per milligram of DNA. On the contrary, NAD+ synthesized from [3H]tryptophan was significantly higher in the clofibrate-treated cells (158% of the control cells) on the basis of nanomoles per hour per milligram of DNA. Clofibrate was inhibitory to tryptophan metabolism as a whole, affecting the glutarate pathway more (decreased to 37% of control) than the kynureninase flux (decreased to 64% of control). As a result, the quinolinate-NAD flux, estimated as the difference in the amounts of tryptophan metabolized by the two metabolic pathways, increased in the clofibrate-treated hepatocytes. The increase in quinolinate during the incubation was 8 times more in the clofibrate-treated cells than in the control cells, which confirmed alteration in the metabolic fluxes of tryptophan in the clofibrate-treated cells. Hepatic quinolinate phosphoribosyltransferase (EC 2.4.2.19) activity increased with dietary clofibrate and returned to the control level 1 week after removing clofibrate from the diet. Nicotinate phosphoribosyltransferase (EC 2.4.2.11) and NAD+ glycohydrolase (EC 3.2.2.5) activities remained unchanged with dietary clofibrate.

Animals↗
PubMed1996

Chemotherapeutic drugs released from polymers: distribution of 1,3-bis(2-chloroethyl)-1-nitrosourea in the rat brain.

PURPOSE: The distribution of [(3)H]BCNU following release from polymer implants in the rat brain was measured and evaluated by using mathematical models. METHODS: [(3)H]BCNU was loaded into p(CPP:SA) pellets, which were subsequently implanted intracerebrally in rats; [(3)H]BCNU was also directly injected into the brains of normal rats and rats with intracranially transplanted 9L gliomas. Concentrations of [(3)H]BCNU on coronal sections of the brain were measured by autoradiography and image processing. For comparison, the kinetics of [(3)H]BCNU release from the p(CPP:SA) polymer discs into phosphate-buffered saline were also measured. RESULTS: High concentrations of BCNU (corresponding to 1 mM) were measured near the polymer for the entire 30-day experiment. The penetration distance, defined as the distance from the polymer surface to the point where the concentration of [(3)H]BCNU in the tissue had dropped to 10 percent of the maximum value, was determined: penetration distance was 5 mm at day 1 and 1 mm at days 3 through 14. Local concentration profiles were compared with a mathematical model for estimation of the modulus phi (2), an indicator of the relative rate of elimination to diffusion in the brain. From day 3 to 14, phi(2) was 7, indicating that BCNU elimination was rapid compared to the rate of diffusive penetration into tissue. The enhanced penetration observed on day 1 appears to be due to convection of extracellular fluid caused by transient, vasogenic edema, which disappears by day 3. CONCLUSIONS: Polymer implants produce very high levels of BCNU in the brain, but BCNU penetration into brain tissue is limited due to rapid elimination.

Animals↗
PubMed1996

Detection of cytokine mRNA-expressing cells in peripheral blood of patients with IgA nephropathy using non-radioactive in situ hybridization.

IgA nephropathy (IgA-N) is considered to be an immune-mediated disorder and several immunological abnormalities have been observed. In the present study, we optimized non-radioactive in situ hybridization and applied this technique to evaluate the degree of expression of various cytokine mRNAs in peripheral blood mononuclear cells (PBMC) taken from patients with IgA-N on cytospin preparation. Using this method, together with image analysis, we examined the expression of mRNA in cells which secrete cytokines, such as IL-2, interferon-gamma (IFN-gamma), IL-4, IL-5 and IL-6. The expression of these mRNAs was clearly observed in monocytes and lymphocytes at a single-cell level. Compared with healthy adults, the expression of IL-4 mRNA, IL-5 mRNA and IL-6 mRNA, but not IL-2 mRNA or IFN-gamma mRNA, was significantly enhanced. Our results indicate that non-radioactive in situ hybridization method is a powerful technique for analysis of cytokine mRNAs in PBMC at a cellular level. Our results also suggest that mRNA expression of IL-4, IL-5 and IL-6, produced by Th2 cells, is increased in patients with IgA-N. The abnormal regulatory process involved in cytokine expression may play an important immunopathologic role in IgA-N.

Adult↗
PubMed1995

Four ferredoxins from Japanese radish leaves.

We detected three ferredoxin components, a, b, and c, in green shoots of Japanese radish seedlings by hydrophobic HPLC analysis using a phenyl-5PW column. All components were also present in mature leaves. Component a was further separated into two components, a1 and a2, by reversed-phase HPLC after carboxymethylation. The existence of four ferredoxins in the photosynthetic tissue of a single plant species is reported here for the first time. Each individual ferredoxin component was isolated, and its primary structure was analyzed for comparison with the two leaf ferredoxins, L-Fds A and B, isolated by Wada et al. (J. Biochem. 105, 619-625 (1989)). The primary structures of components a1, a2, and b were all found in 12 possible structures of L-Fd A deducible from its microheterogeneities. This led us to conclude that L-Fd A is a mixture of three ferredoxins corresponding to components a1, a2, and b. The complete primary structure of component c was established by sequencing of the whole protein and of peptides generated by protease digestion. The N-terminal structure of component c was identical with L-Fd B up to the 11th amino acid residue, suggesting that this component is the same ferredoxin as L-Fd B.

Amino Acid Sequence↗
PubMed1995

Multilayer peroxidase-labeled antibody method: comparison with labeled streptavidin-biotin method, avidin-biotin-peroxidase complex method, and peroxidase-antiperoxidase method.

A new, extremely sensitive, "multilayer peroxidase-labeled antibody method" is introduced. This method utilizes peroxidase-labeled antibodies that immuno-react with their antigen, but also can be an antigen to other peroxidase-labeled antibodies. An example of this method is: use rabbit IgG as the first antibody, peroxidase-labeled goat antirabbit IgG as the second antibody, peroxidase-labeled rabbit antigoat IgG as the third antibody, peroxidase-labeled goat antirabbit IgG as the fourth antibody, and peroxidase-labeled rabbit antigoat IgG as the fifth antibody in succession. We compared the sensitivities of this multilayer peroxidase-labeled antibody method with that of commercially available immuno-peroxidase staining kits, i.e., avidin-biotin-complex method and peroxidase-antiperoxidase method, both by immunostaining and enzyme-linked immunosorbent assay. The generated signal and background in immunostained sections were determined by a computer-assisted image analyzer and by enzyme-linked immunosorbent assay spectrophotometrically. It was found that a maximum signal/background ratio was obtained with those sections reacted with the first four antibodies in succession by the multilayer peroxidase-labeled antibody method, and those reacted with the five antibodies in succession by the multilayer peroxidase-labeled antibody method in the enzyme-linked immunosorbent assay. Thus, the multilayer peroxidase-labeled antibody method is more sensitive than the avidin-biotin-complex method and the peroxidase-antiperoxidase method.

Animals↗
PubMed1995

Effect of feeding clofibrate-containing diet on the hepatic NAD+ level in rats.

Feeding rats with a diet containing 0.25% clofibrate for 2 weeks elevated the hepatic NAD+ and total nicotinate levels significantly. Other peroxisome proliferators, such as 2-(4-chlorophenoxy)propionic acid and di(2-ethylhexyl)phthalate, had similar effects. When rats were fed the control diet without clofibrate for 1 week after 2 weeks of the clofibrate diet, the hepatic NAD+ level returned to the control value. Muscular NAD+ content was not affected by the peroxisome proliferators. The results were discussed in relation to induction of peroxisomal beta-oxidation enzymes by the peroxisome proliferators.

Animals↗
PubMed1995

Laparoscopic surgery for inflammatory bowel disease.

In the setting of inflammatory bowel disease (IBD), laparoscopic approaches have been avoided because of the often fragile intestinal tissue, thickened mesentery, malnutrition, immunosuppression, and the presence of dense adhesions. In this article, we report 10 successfully managed laparoscopic cases in IBD patients (five with ulcerative colitis, five with Crohn's Disease). Patients with ulcerative colitis underwent total abdominal colectomies, mucosal proctectomies, J-pouch construction, and diverting ileostomies. Procedures in patients with Crohn's disease included ileocecectomy (3), sigmoid colectomy with takedown of a transverse colonic fistula (1), and stricturoplasty (1). One of the 10 cases was converted to an open technique for technical reasons. Six of the 10 patients were on high dose corticosteroids for disease control. Hospital stay ranged from 6-13 days, with a median of 7 days. The morbidity rate was 20 per cent, and included one case of mild postoperative pancreatitis in a Crohn's disease patient and one delayed peri-ileostomy fistula in an ulcerative colitis patient. There was no mortality. Based on these results, we conclude that laparoscopic intestinal surgery is both feasible and safe in selected patients with inflammatory bowel disease. Use of laparoscopic techniques in these patients may reduce hospital stay, lessen adhesion formation, and improve cosmetic results in this generally young group of patients.

Adolescent↗
PubMed1995

NAD synthesis from nicotinic acid by the hepatocytes prepared from diabetic rats.

Hepatocytes were prepared from rats 3 and 7 days after a single injection of streptozotocin (50 mg/kg) or alloxan (40 mg/kg). Using the hepatocytes, NAD-and total pyridine nucleotide-syntheses from [carboxyl-14C]-nicotinic acid were investigated. The NAD content of streptozotocin- or alloxan-treated hepatocytes was not significantly different from that of the control hepatocytes. Syntheses of NAD and total pyridine nucleotides from nicotinic acid were significantly elevated 3 days after streptozotocin-injection but only total pyridine nucleotide synthesis was significantly higher 7 days after streptozotocin. Only total pyridine nucleotide synthesis was elevated 3 days after alloxan. Differences in the effects of the two diabetogenic agents and the physiological meaning of an increased NAD synthesis from nicotinic acid in the liver of diabetic animals were discussed.

3-Hydroxybutyric Acid↗
PubMed1994

The core and complementary sequence responsible for biological activity of the diapause hormone of the silkworm, Bombyx mori.

To evaluate the structure-function relationship of the diapause hormone of the silkworm, Bombyx mori, the entire molecule and selected fragment and deleted analogues were chemically synthesized to compare their biological activity. The C-terminal pentapeptide amide was the shortest fragment that elicited 11% diapause eggs at maximum, indicating that this sequence is the core-active structure required for a biological response. The full biological response of about 70% diapause eggs was expressed by the C-terminal hexapeptide amide. However, an ED50 value of this peptide amide was 1000-fold higher than that of the parent molecule. The serial elongation of peptide chain lengths toward the N-terminus brought about the sudden decrease in ED50 values at two positions between Arg9-Gly10 and Thr1-Asp2. The deletion of duplicated sequence(s) located in the middle part of the molecule or the truncation of N-terminal region of the parent molecule increased ED50 values but had no effects on response. Thus, N-terminal region and duplicated sequences act as the complementary structures for full potency of diapause hormone.

Amino Acid Sequence↗