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Biomedical subjects

J Kang

Publications and source records attributed to J Kang.

At least 163 records · Page 9Linked to original sources
PubMed1997

Effect of carbohydrate substrate availability on ratings of perceived exertion during prolonged running.

The purpose of this study was to investigate the effects of carbohydrate substrate availability on ratings of perceived exertion (RPE) during prolonged submaximal running. Thirty marathon runners were recruited as subjects. A double-blind study design was used in which subjects performed an experimental trial that consisted of a 2.5-hr treadmill run at 75-80% VO2max. During the experimental trial, the subjects in the carbohydrate feeding group ingested a 6% glucose and fructose solution at a rate of approximately 60 g.hr, whereas subjects in the placebo group consumed an equal volume of artificially flavored placebo. Statistical analysis of RPE, respiratory exchange ratio, fat and carbohydrate oxidation rate, and blood glucose concentrations indicated that increased carbohydrate substrate availability attenuated the intensity of exertional perceptions during the later stages of prolonged running at 75-80% VO2max in marathon runners.

Adult↗
PubMed1997

Interaction of an adenovirus 14.7-kilodalton protein inhibitor of tumor necrosis factor alpha cytolysis with a new member of the GTPase superfamily of signal transducers.

The adenovirus (Ad) 14.7-kDa E3 protein (E3-14.7K), which can inhibit tumor necrosis factor alpha (TNF-alpha) cytolysis, was used to screen HeLa cell cDNA libraries for interacting proteins in the yeast two-hybrid system. A new member of the low-molecular-weight (LMW) GTP-binding protein family with Ras and ADP-ribosylation factor homology was discovered by this selection and has been named FIP-1 (14.7K-interacting protein). FIP-1 colocalized with Ad E3-14.7K in the cytoplasm especially near the nuclear membrane and in discrete foci on or near the plasma membrane. Its interaction with E3-14.7K was dependent on the FIP-1 GTP-binding domain. The stable expression of FIP-1 antisense message partially protected the cells from TNF-alpha cytolysis. FIP-1 was associated transiently with several unknown phosphorylated cellular proteins within 15 min after treatment with TNF-alpha. FIP-1 mRNA was expressed ubiquitously but at higher levels in human skeletal muscle, heart, and brain. In addition to homology to other LMW GTP-binding proteins, FIP-1 has regions of homology to two prokaryotic metalloproteases. However, there was no homology between FIP-1 and any of the recently isolated death proteins in the TNF-alpha or Fas/APO1 cytolytic pathway and no interaction with several members of the Bcl-2 family of inhibitors of apoptosis. These data suggest that FIP-1, as a cellular target for Ad E3-14.7K, is either a new intermediate on a previously described pathway or part of a novel TNF-alpha-induced cell death pathway. FIP-1 has two consensus sequences for myristoylation which would be expected to facilitate membrane association and also has sequences for Ser/Thr as well as Tyr phosphorylation that could affect its function.

Adenoviridae↗
PubMed1997

In vivo responses of single olfactory receptor neurons of channel catfish to binary mixtures of amino acids.

For the first time in any vertebrate, in vivo responses of single olfactory receptor neurons to odorant mixtures were studied quantitatively. Extracellular electrophysiological response of 54 single olfactory receptor neurons from 23 channel catfish, Ictalurus punctatus, to binary mixtures of amino acids and to their components were recorded simultaneously with the electroolfactogram (EOG). For 57% (73 of 128) of the tests, no significant change (N) from spontaneous activity occurred. Responses to the remaining 55 tests of binary mixtures were excitatory (E; 13%) or suppressive (S; 30%). No response type was associated with any specific mixture across the neurons sampled. Eighty-six percent of the responses of catfish olfactory receptor neurons to binary mixtures were classified similar to at least one of the component responses, a percentage comparable (i.e., 89%) with that observed for single olfactory bulb neurons in the same species to equivalent binary mixtures. The responses of single olfactory receptor neurons to component-similar binary mixtures (i.e., component responses were both E, both S, and both N, respectively) were generally (80% of 59 tests) classified similar to the responses to the components. For E+N and S+N binary mixtures, the N component often (66% of 58 tests) reduced or concealed (i.e., "masked") the excitatory and suppressive responses, respectively. For the majority (6 of 11 tests) of E + S binary mixtures, null activity resulted. Responses to the remaining five tests were either excitatory (n = 3) or suppressive (n = 2).

Action Potentials↗
PubMed1997

Cardiorespiratory and metabolic responses during forward and backward walking.

Level and incline backward treadmill walking techniques are used in the rehabilitation of certain lower extremity injuries (eg., anterior cruciate ligament reconstruction). Of interest to clinicians is the maintenance of cardiorespiratory fitness resulting from these activities. The purpose of the present study was to determine the cardiorespiratory and metabolic stress of backward walking compared with forward walking. The metabolic cost of backward incline walking above a 1% grade has previously not been reported. Seventeen volunteers (11 males and six females, age = 25 +/- 2 years) underwent a forward maximal running test and four random-ordered 6-minute submaximal walking bouts at 93.8 m/min (3.5 mph). The bouts consisted of forward walking at 0% and 5% elevation and backward walking at 0% and 5% elevation. Measurements taken for each exercise session were oxygen uptake, expired ventilation, heart rate, and rating of perceived exertion. Statistical analysis of these dependent variables indicates that: 1) at a given elevation, backward walking elicited greater cardiorespiratory, metabolic, and perceptual responses than forward walking and 2) backward walking at 5% elevation could provide a sufficient stimulus to maintain cardiorespiratory fitness.

Adult↗
PubMed1997

[Effects of 8-methoxypsoralen on smooth muscle of isolated human pulmonary arteries].

OBJECTIVE: To study the effect and mechanism of 8-methoxypsoralen (8-MOP) relaxing human pulmonary arteries. METHOD: Observe effects of 8-MOP on the isolated human pulmonary artery rings(PAR) obtained from 11 patients undergoing lobectomy for lung carcinoma. RESULTS: (1)8-MOP(2 x 10(-5) mol/L) caused significant relaxation of PAR precontracted with noradreline (NA) by 88% (P < 0.001) and this effect of 8-MOP was independent on the endothelium of the pulmonary arteries. (2) The contraction of PAR induced by NA was significantly inhibited by 8-MOP(2 x 10(-5) mol/L) and the percentage of inhibition was 89% (P < 0.001). (3) The contractile dose-response curve of PAR induced by NA was shifted to the right and maximal contractile response was inhibited about 55% by 8-MOP, PD'2 = 4.79. CONCLUSIONS: 8-MOP can significantly relax pulmonary arteries and 8-MOP may become an effective vasodilator for pulmonary hypertension.

Female↗
PubMed1997

[Chemical constituents of Pedicularis muscicola Maxim].

From an ethanolic extract of whole plants of Pedicularis muscicola four glycosidic compounds were isolated. On the basis of chemical and spectal methods, their structurdes were determined to be one lignan glycosied and three iridoid glycosides: syringaresinol-4"-O-beta-D-glucoside (1), sesamoside (2), phloyoside II (3) and caryoptoside (4). All the four compounds were isolated from P. muscicola for the first time, and the compounds 2 and 3 were obtained for the first time from Pedicularis genus.

Drugs, Chinese Herbal↗
PubMed1997

[Separation and determination of plant growth regulators by capillary micellar electrokinetic chromatography].

It is important for separation and determination of plant growth regulators in the research of plant physiology. A study of the separation of five plant growth regulators, such as abscisic acid (ABA), gibberellic acid (GA), indole-butyric acid (IBA), indole acetic acid (IAA) and naphthaleneacetic (NAA) by micellar electrokinetic chromatography (MEKC) is presented. The effects of pH, SDS concentration, applied voltage and organic additives on migration behavior were investigated. Results showed that satisfactory separation was achieved on optimization of electrophoretic condition: 80 mmol/L SDS, 10 mmol/L borate-phosphate, 5% isopropanol, 18 kV applied voltage, pH 8.0. The SDS concentration and organic additives played an important role in separating plant growth regulators, and the applied voltage and pH gave less effect. The detection limit of ABA, GA, IBA, IAA and NAA were 5.0 x 10(-3), 3.0 x 10(-3), 5.8 x 10(-4), 1.5 x 10(-4) and 1.4 x 10(-4) g/L respectively. Increasing of the SDS concentration or organic additives would change separation factor (alpha) and result an improvement of the resolution of difficult separation pairs ABA-GA and IAA-NAA.

Abscisic Acid↗
PubMed1997

[Purification and behavior of recombinant human gamma-interferon on reversed-phase high performance liquid chromatography].

A high performance liquid chromatographic system is described for the purification to homogeneity of recombinant human gamma-interferon (gamma-IFN) from the inclusion bodies produced in genetically transformed Escherichia Coli cells. Crude products of gamma-IFN obtained from typical preparative liquid chromatographic separation on Sephacryl S200 column was applied to analytical HPLC with RP-C18 column and eluted with convex gradient of 0-82% acetonitrile in 30 min followed by linear gradient of 82%-100% in 30 min. A constant level of 0.1% trifluoroacetic acid was maintained throughout the gradient process. The retention of gamma-IFN was investigated as a function of pH, temperature as well as concentration of salt in the mobile phase. For denatured and renatured gamma-IFN the chromatographic profiles were analyzed under various conditions. The retention time of renatured gamma-IFN was compared with that of denatured gamma-IFN and a significant difference in the retention time of profiles was observed. Both biological activities were reduced to different degree followed with incorrect disulfide bond gamma-IFN or oligomer gamma-IFN. The purified gamma-IFN has a specific activity about 6 x 10(6) units/mL. The eluats were assayed for identification of gamma-IFN using Enzyme-Linked Immunosorbent Assays (ELISA). Its molecular weight was 17.5 kD, as determined by SDS-PAGE. The results support that renatured sample with tR = 24.8 min and denatured one with tR = 30.1 min were identical protein with different conformation. The chromatographic behavior is explained by the change in net charge and polarity of gamma-IFN when the mobile phase condition and the conformation vary. The oligomer or incorrect disulfide bonds were formed during gamma-IFN renaturation and also the biological activity was found to be native conformation dependent.

Chromatography, High Pressure Liquid↗
PubMed1997

[The effects of spinal fusion on respiratory function and quality of life in Duchenne muscular dystrophy].

We studied the functional outcome of spinal fusion for the surgical treatment of scoliosis in 8 patients with Duchenne muscular dystrophy (DMD). The mean age of DMD patients at the time of the surgery and the mean follow-up duration was 13.8 (12.3 to 15.4) and 3.9 (1.5 to 6.8) years, respectively. The average spinal angle (Cobb angle) was corrected from 58.8 to 28.6 degrees with the mean corrective rate of 51.3% by the surgical intervention. The correction rate was higher and the corrected Cobb angle remained unchanged during follow-up period in mildly scoliotic patients. Forced vital capacity (FVC) increased post-operatively in 3 patients with moderate scoliosis (Cobb angle: 50 to 80 degrees), indicating that the correction of spinal alignment is effective for the treatment of decreased thoracic volume in DMD. On the other hand, two cases with low % FVC (16.9% and 30.4%, respectively) had poor prognosis in respiratory status. Namely, one died of pneumonia at 17 months after the surgery and the other required mechanical ventilation via nasal mask at 3 years post surgery. Sitting balance improved in all patients, which resulted in more functional use of their upper extremities. During the follow-up period, all patients except one patient who died of pneumonia could maintain sitting balance without support. Moreover these included 2 patients over 20 year old. No complications related to spinal deformities have been found in these patients. Previous study in our hospital showed that 7 of 48 (14.6%) of DMD patients spent all their lives without apparent scoliosis (Cobb angle less than 30 degrees). These suggest that spinal fusion could be recommended for patients with Cobb angle more than 30 degrees and with % FVC more than 35%. Although the impact of spinal fusion upon the life expectancy remains unclear, favorable effect on respiratory function and quality of life can be expected for carefully selected patients with DMD.

Adolescent↗
PubMed1997

Changes in lysyl oxidase activity and calcium content during the healing of tooth extraction wounds.

The typical wound healing process after tooth extraction includes several important biological reactions. The collagen fiber, which is the main organic component of connective tissue, plays an important role in the formation of granulation tissue and also bone tissue. Maturation of collagen is controlled by the intermolecular crosslinks in the collagen fibers. Lysyl oxidase, which catalyzes the corresponding aldehyde formation from certain lysyl and hydroxylysyl residues in collagen and elastin in the first step of the linking reaction, is the only known enzyme required in the crosslinking process. This study was designed to analyze changes in the lysyl oxidase activity and calcium content during the healing of rabbit tooth extraction wounds and to survey the relationship between them. Healing tissue in the extraction sockets was removed 1, 2, 3, 4, 5, 7, 10, 14, 21, 28, and 56 days postoperatively. After decalcification, lysyl oxidase was extracted from wound tissue, and activity of this enzyme was examined by tritium-release assay. Radiographs and histologic sections were also obtained in each group. The results show that lysyl oxidase activity can be detected on the first day postoperatively and that it increases sharply from days five to seven, reaching the peak value on the seventh day. After that, enzyme activity decreases gradually and returns to normal range on day 14. Histologically, the healing sockets were filled mainly with young fibrous connective tissue at day seven; osteoid tissue could be found on the lateral wall and fundus of the extraction sockets at the same time. Accompanying the formation of new bone, calcium content increased conspicuously from day 7 to day 14. These results indicate that lysyl oxidase predominantly acts to promote cross-linking of the abundantly synthesized collagen in the early stage of healing of rabbit tooth extraction wounds. When minerals were precipitated at a great rate in the newly-formed bone, lysyl oxidase activity was concurrently decreased.

Animals↗
PubMed1997

[A case of Kallmann syndrome with empty sella and arachnoid cyst].

We report a 28-year-old man of Kallmann syndrome with arachnoid cyst and empty sella. At age 22, he was admitted with acute slipped capital epiphysis and diagnosed as primary hypogonadotropinemia, because of no response to LH-RH before and after 7-day LH-RH injection. He was treated with androgen for only one year. On his second admission due to femoral head necrosis at age 28, the endocrinological evaluation suggested hypothalamic hypogonadotropinemia. Although he had mild hyposomia, we diagnosed him as Kallmann syndrome, because abnormalities of rhinencephalon was present on MRI. Arachnoid cyst in the middle cranial fossa and empty sella were also observed on MRI and the ballooning of the sella had been advanced on plain X-ray for these 6 years. As Kallmann syndrome is known to be accompanied with midline craniofacial anomalies, the dysplasia of sellar diaphragm might be originated by the same pathogenesis. In this case, empty sella might be caused by impaired CSF dynamics due to arachnoid cyst as well as possible constitutional anomaly of the diaphragm.

Adult↗
PubMed1997

[Electroglottographic studies in myasthenia gravis patients--swallowing in exacerbation and remission stage].

We quantitatively evaluated the electroglottographic changes in swallowing in patients with generalized myasthenia gravis during exacerbation and remission stages. Five patients with myasthenia gravis (Osserman's stage IIB, 55.3 +/- 3.1 years old) and 6 healthy control subjects (55.3 +/- 1.1 years old) were examined. The instrument delivered a 450 microA. 52 kHz carrier signal to a pair of surface electrodes on each side of the larynx at the level of the thyroid lamina. Tissue impedance across the neck was recorded via electroglottography (EGG) while swallowing 10 ml of water. Four trials were performed for each subject, and the EGG waveform was analyzed. The EGG waveform during the exacerbation stage exhibited a more significantly increased number of phases and longer duration than that during remission. In myasthenia gravis patients, the number of phases and the duration from exacerbation to remission was more significantly reduced than those in controls at an interval of 3 years (p < 0.001, p < 0.02). These findings suggest that changes in the number of phases and duration of the EGG waveform are objective and quantitative parameters for measuring therapeutic effectiveness in treating swallowing disturbance due to myasthenia gravis. EGG is a useful and noninvasive technique for evaluating swallowing change in myasthenia gravis patents.

Deglutition↗
PubMed1997

[Nocturnal pulmonary hypertension in patients with obstructive sleep apnea associated with daytime pulmonary hypertension].

We investigated the effect of state-specific changes associated with REM sleep on pulmonary artery pressure in patients with obstructive sleep apnea (OSAS). Six male patients with OSAS (age; 40 +/- 12 SD yrs, BMI; 39.0 +/- 8.6 kg/m2, AHI; 51.5 +/- 28.5) were examined throughout the night by polysomnography, while monitoring pulmonary artery pressure via right cardiac catheterization. All patients had pulmonary hypertension (PH) during periods of wakefulness, and their mean pulmonary artery pressure (PAPm) was 31.1 +/- 7.4 mmHg. PAPm was analyzed at two different points in each apneic episode. PAPbase was the baseline value when inspiratory effects during apnea were not elicited, and PAPpeak was the peak value observed just after the cessation of OSA. PAPpeak was higher in REM (56.3 +/- 12.4) than in NREM (41.4 +/- 6.9 mmHg; P < 0.01), and both values were significantly higher than those observed during periods of wakefulness. The magnitude of elevation of PAP (delta PAP; PAPpeak-PAPbase) in REM and NREM were 11.6 +/- 2.0 and 6.9 +/- 2.8 mmHg, respectively. Relative ratios in the response of PAP to a decrease in O2 desaturation (delta PAP/delta SpO2) showed almost the same value for REM (-0.57 +/- 0.27) and NREM sleep (-0.57 +/- 0.26 mmHg/%). The values of PAPm at SpO2 75% were significantly higher in REM than in NREM (48.7 +/- 11.2 vs. 41.6 +/- 6.2 mmHg). We conclude that transient pulmonary hypertension could be caused not only by hypoxia, but also by state-specific responses (which are unrelated to hypoxia) that occur during REM sleep.

Adult↗
PubMed1996

Entropically driven binding in a self-assembling molecular capsule.

The encapsulation of molecules within larger molecular or supramolecular cages (see ref. 1 for examples) brings about many interesting phenomena, among them the stabilization of reactive intermediates, new forms of stereoisomerism, and templating of the cage itself. Here we describe a self-assembling hydrogen-bonded molecular capsule that encapsulates guest molecules in a reversible, apparently entropy-driven process, giving rise to unusual temperature dependence of the formation process. The positive entropy of formation--at first sight unexpected--seems to be the result of the fact that more than one solvent molecule is included in the 'bare' cage, making their replacement by a single large molecule (here adamantane or ferrocene) entropically favourable.

Adamantane↗
PubMed1996

Assessment of chromatographic peak purity by means of artificial neural networks.

An improved chemometric approach is proposed for assessing chromatographic peak purity by means of artificial neural networks. A non-linear transformation function with a back-propagation algorithm was used to describe and predict the chromatographic data. The Mann-Whitney U-test was used for the concluding the purity of the chromatographic peak. Simulation data and practical analytical data for both pure and mixture samples were analysed with satisfactory results. A prior knowledge of the impurity and the related compound is unnecessary when a slight difference between their chromatogram and spectrum exists. The performance on simulated data sets by this approach was compared with the results from principal component analysis.

Algorithms↗
PubMed1996

Scavenging effects of phenylpropanoid glycosides from Pedicularis on superoxide anion and hydroxyl radical by the spin trapping method(95)02255-4.

The scavenging activities of six phenylpropanoid glycosides, i.e. leucosceptoside A and martynoside, isolated from Pedicularis alashanica Maxim, verbascoside, and pediculariosides A, M and N isolated from Pedicularis striata Pall ssp. arachnoidea Franch Tsoong, on superoxide anion and hydroxyl radicals have been studied by the spin trapping method. The results demonstrated that the number of phenolic hydroxyl groups in the structures of the phenylpropanoid glycosides is related to their scavenging activities. The scavenging effects of the phenylpropanoid glycosides possessing two o-dihydroxyl groups were stronger than the effects of the compounds possessing two o-hydroxy-methoxy groups.

Cyclic N-Oxides↗
PubMed1996

Expression of exogenous p59fyn modulates signaling in an immature B cell line, WEHI-231.

The WEHI-231 B lymphoma line is representative of immature B cells, which undergo growth arrest/apoptosis following cross-linking of surface immunoglobulin M (sIgM). In B cells, sIgM engagement has been shown to induce immediate (within seconds) activation of src family protein tyrosine kinases (PTKs) such as p53lyn/56lyn, p55blk, p56lck and p59fyn which are associated with B cell antigen receptor (BCR) complex. However, p59fyn expression is very low in both normal immature B cells and apoptosis-prone B cell lines, including WEHI-231. Such a finding prompted us to investigate the effects of ectopic expression of p59fyn in growth regulation of WEHI-231 cells. We have obtained WEHI-231 transfectants expressing the exogenous p59fyn by retroviral mediated gene transfer method. The transfectants demonstrated increased [Ca2+]i level in both the non-stimulated condition and sIgM cross-linking. The expression of ectopic p59fyn also increased the sensitivity of the transfectants to growth arrest signal by sIgM cross-linking. The results suggest that p59fyn can modulate signal transduction and growth regulation when expressed in the immature B cell line.

Animals↗