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Biomedical subjects

S Ryu

Publications and source records attributed to S Ryu.

At least 37 records · Page 2Linked to original sources
PubMed2001

Caffeine as a lipolytic food component increases endurance performance in rats and athletes.

Caffeine is one of the famous ergogenic aids in the athletic field. Caffeine has been known to stimulate lipolysis that spares stored glycogen utilization during moderate intensity exercise. Therefore, we investigated the effects of caffeine ingestion on exercise performance in rats and athletes. Rats were administered the caffeine (6 mg/kg) 1 h prior to the exercise then were run on a treadmill at a speed of 20 m/min. They were decapitated at 0 min, 30 min, 60 min of exercise, and exhausted time point. Human subjects ingested the caffeine (5 mg/kg) 1 h prior to the exercise. They exercised on a cycle ergometer at 60% of their VO2max for 45 min, and then the exercise intensity was increased to 80% of their VO2max until exhaustion. Blood and breathing gas samples were collected and calculated every 10 min during exercise. Respiratory exchange ratio of the caffeine trial was significantly lower than that of the placebo trial in the athletes' study (p<0.05). Blood free fatty acid (FFA) levels in studies of both rats and athletes were increased by caffeine ingestion during exercise (p<0.05). Blood lactate levels were also increased during exercise in both rats and athletes (p<0.05). Increased FFA and glycerol concentrations reduced glycogen utilization during exercise compared with placebo group in rats. In addition, endurance time to exhaustion was significantly increased by the caffeine ingestion in both rats and athletes (p<0.05). These results suggest that the caffeine ingestion enhanced endurance performance resulting from spare stored glycogen with increasing lipolysis from adipose tissues and fat oxidation during exercise both in rats and in athletes.

Adipose Tissue↗
PubMed2000

Identification of basic residues involved in drug export function of human multidrug resistance-associated protein 2.

Multidrurg resistance-associated protein 2 (MRP2)/canalicular multispecific organic anion transporter (cMOAT) is involved in the ATP-dependent export of organic anions across the bile canalicular membrane. To identify functional amino acid residues that play essential roles in the substrate transport, each of 13 basic residues around transmembrane regions (TMs) 6-17 were replaced with alanine. Wild type and mutant proteins were expressed in COS-7 cells, and the transport activity was measured as the excretion of glutathione-methylfluorescein. Four mutants, K324A (TM6), K483A (TM9), R1210A (TM16), and R1257A (TM17), showed decreased transport activity, and another mutant, K578A (TM11), showed decreased protein expression. These five mutants were normally delivered to the cell surface similar to the other fully active mutants and wild type MRP2. The importance of TM6, TM16, and TM17 in the transport function of MRP2 is consistent with the previous observation indicating the importance of the corresponding TM1, TM11, and TM12 on P-glycoprotein (Loo, T. W., and Clarke, D. M. (1999) J. Biol. Chem. 274, 35388-35392). Another observation that MRP2 inhibitor, cyclosporine A, failed to inhibit R1230A specifically, indicated the existence of its binding site within TM16.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2000

Determining multiple length scales in rocks

Carbonate reservoirs in the Middle East are believed to contain about half of the world's oil. The processes of sedimentation and diagenesis produce in carbonate rocks microporous grains and a wide range of pore sizes, resulting in a complex spatial distribution of pores and pore connectivity. This heterogeneity makes it difficult to determine by conventional techniques the characteristic pore-length scales, which control fluid transport properties. Here we present a bulk-measurement technique that is nondestructive and capable of extracting multiple length scales from carbonate rocks. The technique uses nuclear magnetic resonance to exploit the spatially varying magnetic field inside the pore space itself--a 'fingerprint' of the pore structure. We found three primary length scales (1-100 microm) in the Middle-East carbonate rocks and determined that the pores are well connected and spatially mixed. Such information is critical for reliably estimating the amount of capillary-bound water in the rock, which is important for efficient oil production. This method might also be used to complement other techniques for the study of shaly sand reservoirs and compartmentalization in cells and tissues.

Journal Article↗
PubMed2000

Kinetics and inhibition of cyclomaltodextrinase from alkalophilic Bacillus sp. I-5.

The cyclomaltodextrinase from alkalophilic Bacillus sp. I-5 (CDase I-5) was expressed in Escherichia coli and the purified enzyme was used for characterization of the enzyme action. The hydrolysis products were monitored by both HPLC and high-performance ion chromatography analysis that enable the kinetic analysis of the cyclomaltodextrin (CD)-degrading reaction. Analysis of the kinetics of cyclomaltodextrin hydrolysis by CDase I-5 indicated that ring-opening of the cyclomaltodextrin was the major limiting step and that CDase I-5 preferentially degraded the linear maltodextrin chain by removing the maltose unit. The substrate binding affinity of the enzyme was almost same for those of cyclomaltodextrins while the rate of ring-opening was the fastest for cyclomaltoheptaose. Acarbose and methyl 6-amino-6-deoxy-alpha-d-glucopyranoside were relatively strong competitive inhibitors with K(i) values of 1.24 x 10(-3) and 8.44 x 10(-1) mM, respectively. Both inhibitors are likely to inhibit the ring-opening step of the CD degradation reaction.

Acarbose↗
PubMed2000

'Full dose' reirradiation of human cervical spinal cord.

With the progress of modern multimodality cancer treatment, retreatment of late recurrences or second tumors became more commonly encountered in management of patients with cancer. Spinal cord retreatment with radiation is a common problem in this regard. Because radiation myelopathy may result in functional deficits, many oncologists are concerned about radiation-induced myelopathy when retreating tumors located within or immediately adjacent to the previous radiation portal. The treatment decision is complicated because it requires a pertinent assessment of prognostic factors with and without reirradiation, radiobiologic estimation of recovery of occult spinal cord damage from the previous treatment, as well as interactions because of multimodality treatment. Recent studies regarding reirradiation of spinal cord in animals using limb paralysis as an endpoint have shown substantial and almost complete recovery of spinal cord injury after a sufficient time after the initial radiotherapy. We report a case of "full" dose reirradiation of the entire cervical spinal cord in a patient who has not developed clinically detectable radiation-induced myelopathy on long-term follow-up of 17 years after the first radiotherapy and 5 years after the second radiotherapy.

Adult↗
PubMed2000

Inhibitory effects of collagen on the PCR for detection of Clostridium perfringens.

It is essential to identify specific food components that inhibit PCR in order to increase the sensitivity of the PCR method for rapid detection of pathogens contaminating a food. We found that collagen, a major component of several foods, inhibited PCR. The inhibitory action of collagen on PCR could be partially reversed by adjusting the concentration of magnesium ion in the reaction mixture and by the use of various DNA extraction methods to remove the collagen from the DNA. Also, the source of thermostable DNA polymerase was affected by the presence of collagen. These results suggest the need to optimize the extraction and assay conditions for rapid detection of enterotoxigenic Clostridium perfringens by PCR with respect to the kind of food being analyzed.

Clostridium perfringens↗
PubMed2000

Hematologic toxic reaction to radiation therapy adjuvant to autologous peripheral blood stem cell transplantation for recurrent or refractory Hodgkin disease.

PURPOSE: To evaluate the hematologic toxic reaction to external-beam radiation therapy after high-dose chemotherapy with peripheral blood stem cell (PBSC) support in patients with Hodgkin disease. MATERIALS AND METHODS: A retrospective study of 30 cases of Hodgkin disease in patients who underwent high-dose carmustine, etoposide, and cyclophosphamide chemotherapy with PBSC support was performed. Thirteen patients underwent radiation therapy (28.8-39.0 Gy) a median of 45 days after PBSC repeat infusion. RESULTS: Radiation therapy was delivered as planned, without interruption, in all patients. Five patients developed thrombocytopenia (one with grade 1 thrombocytopenia; two, grade 2; and two, grade 3) and included three with progressive disease prior to radiation therapy and two with a history of prior irradiation. None developed a bleeding complication or required transfusion support. Five patients who underwent irradiation had thrombocytopenia (three with grade 1 and two with grade 2) 100 days after PBSC repeat infusion, compared with three patients (two with grade 1 and one with grade 3) who did not undergo posttransplantation irradiation. At the most recent follow-up, no patient without evidence of disease had a platelet count of less than 100 x 10(9)/L. CONCLUSION: External-beam radiation therapy was well tolerated in the posttransplantation setting in patients with Hodgkin disease. Thrombocytopenia was common but was not related to clinical complications.

Adolescent↗
PubMed2000

Ventricular arrhythmias with left bundle branch block pattern and inferior axis: assessment of their mechanisms on the basis of response to ATP, nicorandil and verapamil.

The present study investigated the mechanism of ventricular arrhythmias showing left bundle branch block (LBBB) pattern with an inferior axis. The effects of 3 drugs, adenosine triphosphate (ATP), nicorandil and verapamil, were evaluated in 17 patients. ATP suppressed the arrhythmias in 14 patients and nicorandil suppressed them in 8 of those 14. Verapamil suppressed 5 of the 6 ATP-nicorandil-sensitive arrhythmias. Four patients with ATP- or nicorandil-sensitive arrhythmias were not sensitive to verapamil. On the other hand, 3 of the ATP-insensitive arrhythmias were sensitive to neither nicorandil nor verapamil. The QT intervals and QTc were shortened by nicorandil in 5 of the 6 patients who were sensitive to all 3 drugs. One mechanism of suppression by nicorandil could be related to less Ca++ entering the myocardium, which would decrease the duration of the action potential as indicated by the shortened QT intervals. The results suggest that the mechanism of some ventricular arrhythmias is related to triggered activity. Arrhythmias that are sensitive to ATP or nicorandil, but not to verapamil, may be caused by abnormal automaticity. On the other hand, arrhythmias that are insensitive to all 3 drugs might be related to reentry. The features of ventricular arrhythmias with LBBB pattern and inferior axis differ and therefore the causative mechanisms are not the same.

Adenosine Triphosphate↗
PubMed2000

3'UTR polymorphisms in the NRAMP1 gene are associated with susceptibility to tuberculosis in Koreans.

SETTING: Korea University and the Korean Institute of Tuberculosis, Seoul, Korea. OBJECTIVE: To determine whether polymorphisms in the 3' untranslated region (UTR) of the NRAMP1 gene are associated with susceptibility to tuberculosis in Koreans. DESIGN: A case-control study design was used to compare the frequency of 3'UTR of NRAMP1 among 192 tuberculosis patients and 192 healthy individuals. All of the samples were diagnosed by X-ray, smear and culture tests between 1998 and 1999 in the Cross of Lorraine Clinic at the Korean Institute of Tuberculosis. RESULTS: A significant association was found between the Korean tuberculosis patients and polymorphisms in the 3'UTR of the NRAMP1 gene (odds ratio [OR] 1.845; 95% confidence interval [CI] 1.097-3.104; chi2 = 5.424; P = 0.020). CONCLUSION: This study showed that genetic variations in the human NRAMP1 gene are associated with susceptibility to smear-positive tuberculosis in Korean patients. The 3'UTR variant allele associated with susceptibility to tuberculosis is very uncommon in Caucasians, but is present in Koreans and West Africans. These observations may explain in part why African Americans and Koreans have greater susceptibility to tuberculosis than Caucasians.

Alleles↗
PubMed1999

Strong intracellular and negative peripheral expression of fibronectin in tumor cells contribute to invasion and metastasis in papillary thyroid carcinoma.

The intracellular and stromal expression of fibronectin (FN) in invading and central parts of papillary thyroid carcinomas with/without lymph node (LN) metastasis (54 metastasizing cases, 52 non-metastasizing cases) were examined immunohistochemically. The intracellular expression of FN in tumor cells in invading parts was stronger than that in central parts in most cases (79/106 cases, 74.5%). In invading parts, negative stromal FN was frequently found at the periphery of the tumor in cases with extracapsular soft tissue invasion (26/37 cases). Tumor cells in invading parts in metastatic cases were significantly more likely to be negative for stromal FN at the periphery of the tumor than those in non-metastatic cases (P < 0.0001). The strong intracellular and negative stromal FN at the periphery of the tumor in invading parts were associated with invasion and metastasis in papillary thyroid carcinoma. These results suggest that these distinctive characteristics of FN may be useful for understanding invasion and metastasis in vivo.

Adult↗
PubMed1999

Purification of Mlc and analysis of its effects on the pts expression in Escherichia coli.

Products of the pts operon of Escherichia coli have multiple physiological roles such as sugar transport, and the operon is controlled by two promoters, P0 and P1. Expression of the pts P0 promoter that is increased during growth in the presence of glucose is also activated by cAMP receptor protein.cAMP. Based on the existence of a sequence that has a high similarity with the known Mlc binding site in the promoter, the effects of the Mlc protein on the pts P0 promoter expression were studied. In vivo transcription assays using wild type and mlc-negative E. coli strains grown in the presence and absence of glucose indicate that Mlc negatively regulates expression of the P0 promoter, and Mlc-dependent repression is relieved by glucose in the growth medium. In vitro transcription assay using purified recombinant Mlc showed that Mlc repressed transcription from the P0 but did not affect the activity of the P1. DNase I footprinting experiments revealed that a Mlc binding site was located around +1 to +25 of the promoter and that Mlc inhibited the binding of RNA polymerase to the P0 promoter. Cells overexpressing Mlc showed a very slow fermentation rate compared with the wild type when grown in the presence of various phosphoenolpyruvate-carbohydrate phosphotransferase system sugars but few differences in the presence of non-phosphoenolpyruvate-carbohydrate phosphotransferase system sugars except maltose. These results suggest that the pts operon is one of major targets for the negative regulation by Mlc, and thus Mlc regulates the utilization of various sugars as well as glucose in E. coli. The possibility that the inducer of Mlc may not be sugar or its derivative but an unknown factor is proposed to explain the Mlc induction mechanism by various sugars.

Bacterial Proteins↗
PubMed1999

Purification of transcription cofactor complex CRSP.

Transcription of protein coding genes in metazoans involves the concerted action of enhancer binding proteins and the RNA polymerase II apparatus. The cross talk between these two classes of transcription factors is mediated by an elaborate set of cofactor complexes. For the activation of transcription by the promoter specificity protein 1 (Sp1), TATA binding protein-associated factors in the TFIID complex originally were identified as necessary coactivators, but the identity of additional cofactors required for activated transcription was unknown. Recently, we have reported the isolation and properties of a cofactor complex, CRSP (cofactor required for Sp1), which functions in conjunction with the TATA binding protein-associated factors to promote efficient activation of transcription by Sp1. CRSP contains unique subunits as well as polypeptides that are shared with other cofactor complexes. Here, we report a detailed purification protocol for the isolation of CRSP from human HeLa cells. Our purification strategy takes advantage of the ability of CRSP to bind Ni2+-nitrilotriacetic acid-agarose resin as well as other conventional chromatographic resins. We also describe a streamlined purification protocol that allows a more rapid and efficient means to isolate active CRSP.

Chromatography, Affinity↗
PubMed1999

The transcriptional cofactor complex CRSP is required for activity of the enhancer-binding protein Sp1.

Activation of gene transcription in metazoans is a multistep process that is triggered by factors that recognize transcriptional enhancer sites in DNA. These factors work with co-activators to direct transcriptional initiation by the RNA polymerase II apparatus. One class of co-activator, the TAF(II) subunits of transcription factor TFIID, can serve as targets of activators and as proteins that recognize core promoter sequences necessary for transcription initiation. Transcriptional activation by enhancer-binding factors such as Sp1 requires TFIID, but the identity of other necessary cofactors has remained unknown. Here we describe a new human factor, CRSP, that is required together with the TAF(II)s for transcriptional activation by Sp1. Purification of CRSP identifies a complex of approximate relative molecular mass 700,000 (M(r) approximately 700K) that contains nine subunits with M(r) values ranging from 33K to 200K. Cloning of genes encoding CRSP subunits reveals that CRSP33 is a homologue of the yeast mediator subunit Med7, whereas CRSP150 contains a domain conserved in yeast mediator subunit Rgr1. CRSP p200 is identical to the nuclear hormone-receptor co-activator subunit TRIP2/PBP. CRSPs 34, 77 and 130 are new proteins, but the amino terminus of CRSP70 is homologous to elongation factor TFIIS. Immunodepletion studies confirm that these subunits have an essential cofactor function. The presence of common subunits in distinct cofactor complexes suggests a combinatorial mechanism of co-activator assembly during transcriptional activation.

Antibodies↗
PubMed1999

Impact of hypertension guideline implementation on blood pressure control and drug use in primary care clinics.

BACKGROUND: A worsening of blood pressure control has occurred in the 1990s despite the availability of sophisticated technologic, pharmacologic, and educational advances applicable to hypertension care. Clinical guidelines that are intended to improve hypertension care by making specific recommendations on drug use, frequency of follow-up care, and target levels of blood pressure have been developed. METHODS: The Institute for Clinical Systems Integration's (ICSI's; Minneapolis) Hypertension Treatment Guideline was developed in 1994 and is updated annually. This study employed a quasi-experimental, before-and-after design at two medical groups to assess changes in the care provided to patients 18 years of age and older with identified hypertension (International Classification of Diseases-9 codes 401.0, 401.1, or 401.9). RESULTS: Among adults with hypertension, the proportion meeting the blood pressure goal of < 140/90 mm Hg increased from 36.8% (of 685 patients) preguideline to 50.3% (of 928 patients) postguideline (chi-square = 29.4, p < 0.001); the mean arterial pressure decreased from 102.7 mm Hg to 99.4 mm Hg (t = 5.45, p < 0.001). Cohort analysis of patients enrolled at both points in time confirmed these findings and showed an increase in the number of office visits from 5.4 to 6.7 visits per patient per year after guideline implementation (F = 10.9, p = 0.001). The use of a guideline-recommended medication for treatment of blood pressure was 35.9% preguideline and 36.2% postguideline. CONCLUSIONS: Implementation of a hypertension treatment guideline in primary care clinics was related to significantly improved hypertension control. Identification, tracking, and active outreach to patients with hypertension were used by all clinics.

Adult↗
PubMed1999

Resection and permanent I-125 brachytherapy without whole brain irradiation for solitary brain metastasis from non-small cell lung carcinoma.

We assessed a treatment plan of local therapy (resection and placement of permanent low dose-rate I-125 seeds) without whole brain irradiation in 15 patients with solitary brain metastasis (SBM) from primary non-small cell lung cancer between January, 1991 and May, 1996. Thirteen lesions were confirmed as solitary by MRI scan, and 2 patients had CT scan only. With median follow up of 14 months, 3 patients remain alive at 6, 33, and 62 months post-resection. Median survival is 14 months for all patients and 26 months for patients with SBM as the only site of disease. Five tumors failed in the brain: 2 solitary recurrences adjacent to the site of SBM, 2 multiple metastases outside the primary site, and 1 multiple recurrence including the primary site. No failures were seen with SBM <2.5 cm. Only 2 of 13 patients with SBM confirmed with MRI experienced relapses elsewhere in the brain. Recurrence rates both adjacent and outside the area of the initial brain lesion are similar to studies employing resection plus whole brain irradiation (WBI), and the patient is spared the acute and potential late toxicity of WBI. This approach may be considered for selected patients with solitary brain metastases (SBMs), although further experience with larger patient numbers is needed.

Brachytherapy↗
PubMed1999

The meaning of public health nursing: creating 24 hour care in a community in Japan.

This case study describes the strategies and activities of public health nurses to increase the availability of services in a municipality of 36,000 and to transform community attitudes so that those needing services would feel free to use them. Strategies and activities are seen in the context of Japan, Minakuchi Town and the leadership of the chief public health nurse. Practicing in partnership with members of the community, strategies of public health nurses include technical activities (conducting needs assessment and framing program alternatives) and information sharing and health education (e.g. 75 meetings organized with health promoters for residents in the districts of the town). On the basis of the results of Minakuchi Town, viewed as an example of expert public health nursing practice, a general model for public health nursing practice is presented.

Adult↗