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Biomedical subjects

S Kim

Publications and source records attributed to S Kim.

At least 1,135 records · Page 63Linked to original sources
PubMed1991

Increased production of angiotensin II in the adrenal gland of stroke-prone spontaneously hypertensive rats with malignant hypertension.

Angiotensin(Ang) contents in the adrenal gland of stroke-prone spontaneously hypertensive rats(SHRSP) and age-matched Wistar Kyoto rats(WKY) were determined using reverse phase high performance liquid chromatography combined with a specific radioimmunoassay. In normotensive 5 wk-old SHRSP, the adrenal renin activity was about 3 times higher than that of age-matched WKY while the adrenal Ang I and Ang II concentrations did not differ from those of WKY. In the severely hypertensive 25 wk-old SHRSP, the adrenal Ang II and Ang I, and plasma aldosterone concentrations were about 5-fold, 2-fold and 4-fold, respectively, increased compared with levels in the WKY. In the 25 wk-old SHRSP 24 h after bilateral nephrectomy, the adrenal Ang II and plasma aldosterone levels were not decreased and were 10 and 3 times, respectively, higher than those of nephrectomized control WKY. Thus, the enhanced local generation of Ang II in the adrenal gland may contribute to the increased release of aldosterone in SHRSP with malignant hypertension.

Adrenal Glands↗
PubMed1991

Kinetics of expression of multiply spliced RNA in early human immunodeficiency virus type 1 infection of lymphocytes and monocytes.

The genome of human immunodeficiency virus type 1 (HIV-1) encodes at least six proteins involved in regulation as well as the structural proteins Gag, Pol, and Env. The interplay of the various regulators generates early and late transcriptional phases in the HIV-1 life cycle; the earliest RNA is enriched in subgenomic species, and the genomic transcript appears at the later stage of infection. We investigated the nature of the mRNAs expressed in the early stages of infection when the 2 kilobase subgenomic species predominate. RNA was analyzed in the early phase of a one-step growth cycle of HIV-1 infection in T-lymphoid and monocytic cell lines by using PCR amplification of in vitro-synthesized viral cDNAs. In both cell lines, expression of Tat-, Rev-, and Nef-specific messages appeared simultaneously and could be detected within 8-12 hr of infection but in different amounts with a predominance of Nef-specific message. The Env-specific message could be detected as early as the Rev-specific message, indicating that expression of at least small amounts of the singly spliced message could occur before the accumulation of Rev.

Antisense Elements (Genetics)↗
PubMed1991

Similarity between physicochemical properties of recombinant rat prorenin and native inactive renin.

Rat prorenin was synthesized by Chinese-hamster ovary cells transfected with an expression vector containing rat preprorenin cDNA sequences, then purified by concanavalin A-Sepharose chromatography and h.p.l.c. on G3000SW. The molecular mass of purified prorenin was 46,000 Da, as determined by h.p.l.c. on G3000SW. Immunoblot analysis indicated that recombinant prorenin cross-reacted with anti-(mature renin) antibody and two kinds of antibodies recognizing the N-terminus and C-terminus of the prosegment of rat prorenin. Recombinant prorenin was bound to a Cibacron Blue-Sepharose column and eluted with 1.4 M-NaCl, but was not retained by an octapeptide renin inhibitor (H-77)-Sepharose column. Trypsin activation of prorenin increased the renin activity 110-fold, caused binding to an H-77-Sepharose column and nullified the reactivity to the above two kinds of anti-prosegment antibodies, findings indicating that the activation of prorenin with trypsin is due to the cleavage of the prosegment. Rat plasma inactive renin, partially purified by h.p.l.c. on G3000SW, had much the same physicochemical characteristics as the recombinant prorenin. These results provide evidence that rat plasma inactive renin is prorenin. Recombinant prorenin is a useful material for examining the physiological role of circulating prorenin.

Animals↗
PubMed1991

Phase I and pharmacokinetic trial of intraperitoneal etoposide in combination with the multidrug-resistance-modulating agent dipyridamole.

Dipyridamole synergistically enhances the sensitivity of human ovarian carcinoma cells to etoposide in vitro. We conducted a phase I trial to investigate the feasibility of using dipyridamole to selectively increase the sensitivity to etoposide of tumors confined to the peritoneal cavity. Etoposide and dipyridamole were administered as a continuous 72-hour intraperitoneal infusion to 16 patients. The maximum tolerated dose of etoposide was 175 mg/m2 per day when administered with dipyridamole at a fixed dose of 24 mg/m2 per day. Dose-limiting toxic effects were leukopenia and thrombocytopenia. No other major toxic effects were observed. The free peritoneal etoposide and dipyridamole concentrations varied with the etoposide dose rate, reaching 218.9 and 25.3 microM, respectively, at an etoposide dose rate of 175 mg/m2 per day. The free etoposide and dipyridamole concentrations attained were well within the range needed for synergistic interaction.

Adult↗
PubMed1991

[MRI evaluation of the patellar articular cartilage in patients with subluxation of the patella].

In patients with subluxation of the patella, injury of the patellar articular cartilage is frequently observed and correct evaluation is important to manage these patients. We examined 11 patients with subluxation of the patella and five normal volunteers. In 12 patellofemoral joints of seven patients with subluxation of the patella, the abnormalities observed on MRI were compared with those on arthroscopy and/or at operation. MRI was performed with a Magnetom 1.5 T (Siemens) using the round surface coil. Pulse sequences were SE (TR 400 ms/TE 19 ms), FLASH (TR 320 ms/TE 15 ms FA 90 degrees and 40 degrees), and SE (TR 2000 ms/TE 26, 70 ms). We analysed MR findings of the 12 abnormal joints and 10 normal joints according to the following classification of abnormalities observed on arthroscopy. (1) normal appearance (n = 3 joints), (2) softening and fibrillation (n = 6), (3) fragmentation (n = 3), and (4) erosion to bone (n = 0). In only one of the six cases with softening and fibrillation observed on arthroscopy, MRI could visualize the thickening of patellar articular cartilage, but in all three cases with fragmentation observed on arthroscopy, MRI could visualize the thin inhomogenous cartilage with irregular surface. The combination of SE (TR 400 ms/TE 19 ms) and FLASH (TR 320 ms/TE 15 ms FA 90 degrees) are extremely effective pulse sequence to detect the abnormalities of patellar articular cartilage. We conclude that MRI is a useful noninvasive method of detecting advanced changes in patellar articular cartilage.

Adolescent↗
PubMed1991

Amino-terminal amino acid sequence and heterogeneity in glycosylation of rat renal renin.

We isolated 7.4 mg of pure renin from 2 kg of rat kidneys using affinity chromatography on pepstatin-aminohexyl-Sepharose and an octapeptide renin inhibitor, H-77-Sepharose. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that renin consists of two polypeptide chains linked by a disulfide bond, one of Mr = 36,000 (heavy chain) and the other of Mr = 3,000 (light chain). The amino-terminal 10-amino acid sequences of the heavy and the light chains were identical to the sequences beginning at Ser72 and Asp355, respectively, of the amino acid sequence of preprorenin deduced from the renin cDNA sequence. Amino acid sequencing of the carboxyl-terminal peptide of the heavy chain, generated by digestion with lysyl endopeptidase, showed that the carboxyl-terminal residue of the heavy chain is Phe. Thus, the propeptide of prorenin is cleaved after Thr71, followed by removal of two amino acids, Arg353 and Asn354, the result being formation of the heavy and light chains. Thus, the site of cleavage of rat prorenin is after a nonbasic amino acid, in contrast to the cleavage of the propeptide after a pair of basic amino acids in mouse submaxillary renin, human renal renin, and many secretory proteins. Treatment of renin with neuraminidase or glycopeptidase F had no apparent effect on the charge heterogeneity of renin. Glycosylation probably does not contribute to charge heterogeneity.

Amino Acid Sequence↗
PubMed1991

Pyrimidine catabolism in Pseudomonas aeruginosa.

Pyrimidine catabolism in Pseudomonas aeruginosa was investigated. It was found that the pyrimidine bases uracil and thymidine as well as their respective reductive catabolic products could be utilized as sole sources of nitrogen. Reductive degradation of the pyrimidine bases was noted. The reductive catabolic pathway enzymes dihydropyrimidine dehydrogenase, dihydropyrimidinase and N-carbamoyl-beta-alanine amidohydrolase were all detected in minimal medium grown cells. Induction of pyrimidine catabolism by uracil was observed in this pseudomonad. Pyrimidine degradation in P. aeruginosa was not subject to catabolite repression.

Amidohydrolases↗
PubMed1991

TEM immunogold staining of C3 from plasma onto titanium oxides.

Immunogold staining in conjunction with TEM was used to observe C3 adsorption from plasma in relation to the underlying titanium structure of thermal, anodic, and electropolished oxides. Heat treatments and oxide thickness were found to have no significant effect on the adsorption behavior of C3, while surface oxide type possibly has. Surface concentration of C3 was found to be time- and plasma concentration-dependent. Evidence is given for the possible involvement of C3 in protein exchange, i.e., the Vroman effect. Diluted plasma resulted in a random distribution of gold colloids, whereas clustering occurred with undiluted plasma. Although C3 concentrations present on grain boundaries followed the same trend as that found on the surface, C3 was found to have a higher grain boundary than bulk concentration for 0.1% plasma.

Adsorption↗
PubMed1991

In situ testing of CO2 laser on dental pulp function: effects on microcirculation.

The effect of CO2 laser irradiation on pulpal microcirculation was studied in cat canines. The enamel surfaces of 4 teeth were exposed with energy densities of 304-1440J/cm2, using either a handpiece or a microslad, with a focal spot of 0.21mm and 0.33mm respectively. Pulpal blood flow (PBF) before and following lasing was recorded through the intact tooth surface by a laser Doppler flowmeter. CO2 laser irradiation caused an increase in PBF, which was immediate and transient. The PBF increase was higher in a large pulp than in a small pulp, and it was inversely related to the focal spot size. These findings confirm that the dental pulp is thermally affected by CO2 lasing of the tooth surface, however, without extensive pulp coagulation. It is concluded that the effects of laser irradiation on the pulpal microcirculation may be studied in situ by means of the presented methodology.

Animals↗
PubMed1991

Transcriptional activation by upstream activator sequences requires distinct interactions with downstream elements in the yeast TRP1 promoter.

The interactions between different upstream activator sequences (UAS) and the downstream transcriptional elements of the TRP1 promoter were studied. We have inserted the UAS from the PGK gene into a series of TRP1 promoter deletions such that the PGK UAS is positioned at various distances upstream from or replaces the TRP1 UAS (UAST1). We show that activation of the TRP1 transcription unit I by the PGK UAS shows a marked position dependence, which is solely a function of the position of the PGKUAS relative to sequences involved in the determination of the RNA initiation sites in the TRP1 promoter. No cooperative activation is seen when both UASs are present in the promoter; the PGK UAS is dominant and is not repressed by the TRP1 negative element. In addition, we show that the PGK and TRP1 UASs interact differently with TATA sequence at the TRP1 RNA initiation site. Our results suggest that these UASs are functionally distinct because they use different mechanisms for activating heterologous promoters.

Aldose-Ketose Isomerases↗
PubMed1991

Multivesicular liposomes containing bleomycin for subcutaneous administration.

Optimal cancer treatment with cell-cycle-specific agents requires maintenance of a cytotoxic drug level for a prolonged period. We explored the use of multivesicular liposomes as a slow-release depot of bleomycin for systemic administration via the s.c. route. The average volume-adjusted liposome size was 19.1 microns, the half-life of leakage in human plasma was 32.1 h, and the half-life of s.c. liposomal bleomycin was 31.8 h. When tested against the s.c. B-16 melanoma model in BDF1 mice, the therapeutic index of single-dose bleomycin given s.c. was significantly improved when the drug was encapsulated in multivesicular liposomes. The efficacy was improved as assessed by both inhibition of tumor growth and increased life span, and the toxicity appeared to be decreased.

Animals↗
PubMed1991

Crystallization and a preliminary X-ray crystallographic study of alpha-amylase from Bacillus licheniformis.

alpha-Amylase from Bacillus licheniformis has been crystallized by the hanging-drop vapor diffusion method in the presence of calcium ions using ammonium sulfate as precipitant. The crystals are tetragonal, belonging to the space group P4(1)2(1)2 (or P4(3)2(1)2), with unit cell dimensions of a = 119.9 and c = 85.4 A. The asymmetric unit contains one molecule of alpha-amylase, with a crystal volume per protein mass (VM) of 2.78 A3/Da. The crystals diffract to better than 2.0 A Bragg spacing when exposed to synchrotron X-rays and they are reasonably stable in the X-ray beam. Thus the crystals are suitable for structure determination at high resolution by X-ray methods.

Bacillus↗
PubMed1991

Decreasing intradental nerve activity in the cat with potassium and divalent cations.

Nerve activity was recorded from deep dentinal cavities in the canine teeth to assess the possible influence of potassium and divalent cations in decreasing this activity in hypersensitive teeth. The decreased activity after the topical application of 0.756 mol/l KCl to the cavity was primarily due to the cation. KCl elicited a biphasic response from intradental nerves, an initial transient excitatory response followed by a prolonged inhibitory period. During the inhibitory period 3 mol/l NaCl, an effective excitatory stimulus, failed to evoke intradental nerve activity. However, with time the response to 3 mol/l NaCl eventually recovered to its previous control level. Close, intra-arterial injection of KCl showed the same biphasic response and time-course of intradental nerve activity as with topical application. Therefore, whether KCl was applied topically or injected its effectiveness in altering the nerve activity was similar. Pretreatment of the dentinal cavity with CaCl2, MgCl2 or SrCl2 greatly reduced the response of intradental nerves to KCl. Therefore these divalent cations seem to have a depressant action on pulpal nerve fibres. The mechanism of action of KCl seems to be an alteration of K+ concentration immediately surrounding the intradental nerves which presumably depolarizes the nerve fibre membrane and elicits an initial firing of action potentials. Because of the persisting high levels of extracellular potassium a sustained depolarized state occurs that results in an inactivation of the action potential. Divalent cations appear to depress the excitability of the nerve cell membrane without altering membrane potential. Such ionic agents could be used in conjunction with KCl as a possible treatment for hypersensitive teeth.

Action Potentials↗
PubMed1991

An enzyme-linked immunosorbent assay for myelin basic protein-specific protein methylase I.

A sandwich enzyme-linked immunosorbent assay (ELISA) has been developed to determine myelin basic protein (MBP)-specific protein methylase I. Rabbit immunoglobulin anti-bovine MBP-specific protein methylase I, purified by Sepharose-A affinity chromatography, was utilized as the primary antibodies, while the same antibodies which had been conjugated to peroxidase were employed as the indicator antibodies. This assay method was about 280 times more sensitive than the conventional trichloracetic acid (TCA) precipitation method. Employing the ELISA, the level of MBP-specific protein methylase I during mouse brain development was examined; the peak level of the methylase was shown to be at 16th postnatal day, indicating temporal correlation with myelination. Among several species of brains examined, human showed the highest and carp the least amount of MBP-specific protein methylase I; 6.33 micrograms and 0.33 micrograms per mg of brain cytosol protein, respectively. Dysmyelinating jimpy hemizygous mouse brain showed the immunoreactive MBP-specific protein methylase only 60% that of the control at 20 days of age. The high sensitivity of the method together with the fact that MBP-specific protein methylase is present in human cerebrospinal fluid suggests a possible clinical application of this method for evaluating demyelinating disorders.

Animals↗