Biomedical subjects
Publications and source records attributed to J Kim.
A boy now 8 years old presented at 21 months of age with developmental arrest, followed by regression, cortical blindness and myoclonic seizures. Urine organic acid analysis revealed 3-hydroxy-2-methylbutyric acid and tiglyglycine; 3-ketothiolase enzyme activity was normal and he was subsequently found to have 3-hydroxy-2-methylbutyryl-CoA dehydrogenase deficiency.
BACKGROUND: Prolongation of spinal anesthesia by oral clonidine premedication has been known. We hypothesized that intravenous clonidine administered after the spinal block may prolong spinal anesthesia. METHODS: To assess the prolongation of spinal anesthesia by intravenous clonidine, we designed a double-blind, placebo-controlled, prospective study. Patients scheduled for orthopedic surgery received 12 mg of 0.5% hyperbaric bupivacaine and were randomly divided into three groups (n = 26 in each group). In the clonidine 10-min group, 3 microg x kg-1 of clonidine was administered for 10 min immediately after the spinal block. In the clonidine 60-min group, 3 microg x kg-1 of clonidine was administered for 10 min, 50 min after the spinal block. The control group received normal saline. Sensory block was evaluated by pinprick and the duration was defined as the time for sensory block to regress to L1 dermatome. Duration of motor block was defined as the time required for the patient to flex his or her knee. RESULTS: The duration of sensory block was longer in both the clonidine 10-min and clonidine 60-min groups compared with the control group (196 +/- 42 min, 179 +/- 41 min vs. 125 +/- 25 min, P < 0.05). The duration of motor block was longer in the clonidine 10-min group than in the control group (153 +/- 26 min vs. 131 +/- 29 min, P < 0.05). The lowest heart rate and mean blood pressure were not different among groups. CONCLUSIONS: Intravenous clonidine administration within 1 h after the spinal block prolonged bupivacaine spinal anesthesia for approximately 1 h without adverse effects.
We obtained scanning near-field optical microscopy images to study the excitation of surface plasmons on metallic dots fabricated using scanning probe lithography. Gold nano-dots were fabricated by applying electric voltages to conducting probes installed in an atomic force microscope using the mechanism of field-induced diffusion and nano-oxidation plus Au-coating. High spatial resolution of scanning near-field optical microscopy revealed a 'bifold' pattern of surface plasmon mode on fabricated Au dots in the polarization direction of incident light. We found that scanning near-field optical microscopy imaging combined with scanning probe lithography is able to provide a systematic study of surface plasmon excitation on nano-metallic structures.
Plants often respond to attack by insect herbivores and necrotrophic pathogens with induction of jasmonate-dependent resistance traits, but respond to attack by biotrophic pathogens with induction of salicylate-dependent resistance traits. To assess the degree to which the jasmonate- and salicylate-dependent pathways interact, we compared pathogenesis-related protein activity and bacterial performance in four mutant Arabidopsis thaliana lines relative to their wild-type backgrounds. We found that two salicylate-dependent pathway mutants (cep1, nim1-1) exhibited strong effects on the growth of the generalist biotrophic pathogen, Pseudomonas syringae pv. tomato, whereas two jasmonate-dependent pathway mutants (fad3-2fad7-2fad8, jar1-1) did not. Leaf peroxidase and exochitinase activity were negatively correlated with bacterial growth, whereas leaf polyphenol oxidase activity and trypsin inhibitor concentration were not. Interestingly, leaf total glucosinolate concentration was positively correlated with bacterial growth. In the same experiment, we also found that application of jasmonic acid generally increased leaf peroxidase activity and trypsin inhibitor concentration in the mutant lines. However, the cep1 mutant, shown previously to overexpress salicylic acid, exhibited no detectable biological or chemical responses to jasmonic acid, suggesting that high levels of salicylic acid may have inhibited a plant response. In a second experiment, we compared the effect of jasmonic acid and/or salicylic acid on two ecotypes of A. thaliana. Application of salicylic acid to the Wassilewskija ecotype decreased bacterial growth. However, this effect was not observed when both salicylic acid and jasmonic acid were applied, suggesting that jasmonic acid negated the beneficial effect of salicylic acid. Collectively, our results confirm that the salicylate-dependent pathway is more important than the jasmonate-dependent pathway in determining growth of P. syringae pv. tomato in A. thaliana, and suggest important negative interactions between these two major defensive pathways in the Wassilewskija ecotype. In contrast, the Columbia ecotype exhibited little evidence of negative interactions between the two pathways, suggesting intraspecific variability in how these pathways interact in A. thaliana.
Thirty-two colostrum-deprived conventional pigs aged 28 days were co-infected with Korean isolates of porcine circovirus 2 (PCV2) and porcine parvovirus (PPV) and observed for up to 35 days post-inoculation (dpi). Histopathologically, granulomatous inflammation, with or without intracytoplasmic inclusion bodies, was present in lymphoid tissues (e.g., lymph nodes, thymus, spleen and tonsil) from 20 dpi, being most severe at 24 dpi. PCV2 and PPV DNA were detected in the lymph nodes from 3 to 35 dpi by in-situ hybridization, but the labelling for both viruses was particularly intense and widespread at 20 and 24 dpi. A close relationship between the cells labelled for PCV2 and those labelled for PPV was revealed by examination of serial sections from lymph nodes, and PCV2 and PPV were also detected in peripheral blood monocytes from 3 to 35 dpi. Other tissues and cells in which PCV2 and PPV DNA were detected included macrophages in the tonsil, thymus, spleen, lung, liver, kidney and heart. Significantly more PCV2-positive cells than PPV-positive cells were detected in the lymph nodes at 5 to 35 dpi. The pathogenesis of postweaning multisystemic wasting syndrome (PMWS) reproduced in this study may be suggested thus: initial viral entry through tonsillar macrophages, followed within 3 days by viraemia; PCV2 and PPV replicate, at least to some extent, in circulating peripheral monocytes, contributing to the cell-associated viraemia and to viral distribution throughout the lymphoid tissues.
A solitary plasmacytoma occurring in the mandible of a 15-year-old Korean male 6 years after renal transplantation is reported. The tumour presented as a hyperplastic gingival overgrowth in the right madibular molar area. Histology and immunohistochemistry revealed plasmacytoma and monoclonality of the kappa chain and IgG. In situ hybridization for Epstein-Barr virus encoded RNA (EBER) showed positive signals in the tumour cells. The tumour regressed after reducing the immunosuppressive agents with concurrent radiotherapy. The patient remains in a stable condition with normal renal functions after 7 years without recurrence. This case confirms that Epstein-Barr virus associated B-lymphoproliferative disorders are still a major complication of immunosuppression.
Explore the source record for details and available documents.
AnyHeart is a single-piece, implantable biventricular assist device. This electromechanical BVAD has a moving-actuator mechanism. To monitor the status of AnyHeart from anywhere at any time, a portable personal digital assistant (PDA) monitor and web-based remote monitoring system were developed. The PDA local monitoring system has replaced bulky personal computer monitoring systems. The web-based remote monitoring system has several functions such as data collecting, storing, and posting through the internet. Basically, interventricular pressure (IVP) is a parameter indicating the filling level of the blood chambers of AnyHeart. The pump output can be estimated using IVP, which is acquired noninvasively from AnyHeart. With the proposed method, we can estimate the pump output with a small margin of error.
An assist flow estimation scheme for a moving-actuator biventricular assist device (MA-BVAD) using interventricular pressure (IVP) has been developed. The scheme uses a waveform feature parameter of IVP, peak IVP time (PIT), for estimation of the filling volumes of both left and right blood sacs simultaneously. In a regression analysis on data from an in vivo test in an 85 Kg male calf for 20 days, the PIT was found to have high correlation with the blood sac filling volume (R=0.883: left filling volume, R=0.967: right filling volume). A conceptual equation hypothesizing this correlation between PIT and filling volume was established based on the observation and the unknown parameters were identified using least squares parameter optimization. The estimation equation identified proved highly accurate (R=0.916 for left flow, R=0.970 for right flow). The accuracy of the estimation scheme promises very good practical applicability.
Monocyte chemoattractant protein-1 (MCP-1) but not interleukin-8 (IL-8) was detected by in situ hybridization using a nonradioactive digoxigenin-labeled complementary DNA probe in granulomatous lesions of lymph nodes from 20 pigs with naturally occurring postweaning multisystemic wasting syndrome (PMWS). Complementary DNA probes of 375 and 266 base pairs for MCP-1 and IL-8, respectively, were generated by reverse transcription-polymerase chain reaction. The 20 pigs with PMWS had distinct positive hybridization signals for MCP-1 but not for IL-8. The hybridization signals for MCP-1 were strictly confined to the cells with granulomatous lesions, including macrophages and multinucleated giant cells. A very close cell-to-cell correlation between MCP-1 and porcine circovirus 2 was seen in serial sections of lymph nodes. Results of this study indicate that MCP-1 expression may play a role in the pathogenesis of granulomatous inflammation in pigs with PMWS.
The prediction of the spatial and temporal flow regime is important for the efficient design and operation of the settling tank. The impact of the gravity current has been investigated by the temperature difference or artificial glass particles. This experimental study is designed to obtain the steady state of stratified flow with the consideration of the heavy density flow. Two different approaches were performed at lab scale considering the hydraulic similarity. One is the investigation of a heavy density current of saline water intrusion. The characteristics of the internal hydraulics are monitored using Particle Image Velocimetry (PIV). As a result of the saline intrusion, the internal flow established a continual density stratification of 3-layers in steady state. The other is the movement of activated sludge from a sewage treatment plant. The video image is captured to analyze the behavior of activated sludge in the settling tank. The experiments with various inlet baffle conditions suggest that the hydraulic characteristics of the two experiments are significantly different. As the distance between the baffle and inlet point was decreased, significant strength of saline density currents in the bottom layer was observed. However, the strength of the velocity in the bottom density currents appeared to be the opposite in the case of the activated sludge. The reason for the slower density current in the bottom layer is associated with the compressibility of activated sludge characteristics.
The development of bioreactor landfills originated with the recognition that the sequential acid and methane fermentation phases of anaerobic waste stabilization could be accelerated by leachate recirculation. Original studies suggested the potential for such a change in design and management of landfills receiving both municipal and industrial solid wastes, followed by both pilot- and full-scale bioreactor landfill demonstrations. The enhancement of waste transformation within controlled bioreactor landfills is addressed in terms of the sequential phases of waste stabilization, temporal and spatial distribution of leachate and gas generation patterns, mechanisms of conversion, and proposed process and operational modifications. Selected results from investigations on bioreactor landfills include co-treatment of organic and inorganic constituents and the use of dedicated treatment zones.
This paper describes a novel hybrid-modeling paradigm for the simulation of surgical tool-soft tissue interactions in real time medical simulations using force feedback. A local point collocation-based method of finite spheres is coupled with a global boundary element technique to capture local features of the interaction (e.g., nonlinearities of the soft tissue) without sacrificing global accuracy. The technique is demonstrated using realistic examples.
We measured leg blood flow (LBF), drew arterial-venous (A-V) blood samples, and calculated muscle O(2) consumption (VO(2)) during incremental cycle ergometry exercise [15, 30, and 99 W and maximal effort (maximal work rate, WR(max))] in nine sedentary young (20 +/- 1 yr) and nine sedentary old (70 +/- 2 yr) males. LBF was preserved in the old subjects at 15 and 30 W. However, at 99 W and at WR(max), leg vascular conductance was attenuated because of a reduced LBF (young: 4.1 +/- 0.2 l/min and old: 3.1 +/- 0.3 l/min) and an elevated mean arterial blood pressure (young: 112 +/- 3 mmHg and old: 132 +/- 3 mmHg) in the old subjects. Leg A-V O(2) difference changed little with increasing WR in the old group but was elevated compared with the young subjects. Muscle maximal VO(2) and cycle WR(max) were significantly lower in the old subjects (young: 0.8 +/- 0.05 l/min and 193 +/- 7 W; old: 0.5 +/- 0.03 l/min and 117 +/- 10 W). The submaximally unchanged and maximally reduced cardiac output associated with aging coupled with its potential maldistribution are candidates for the limited LBF during moderate to heavy exercise in older sedentary subjects.
The random energy model (REM) for the critical points (saddles and minima) of the potential energy landscape of liquids is further developed. While thermodynamic properties may be calculated from the unconditional distribution of states G(E), dynamics requires the distribution G(c)(E';E) of energies E' of neighbors connected to a state with energy E. Previously it was shown [T. Keyes, Phys. Rev. E 62, 7905 (2000)] that an uncorrelated REM, G(c)(E';E)=G(E'), is badly behaved in the thermodynamic limit N--> infinity. In the following, a simple expression is obtained for G(c)(E';E), which leads to reasonable N dependences. Results are obtained for the fraction f(u) of imaginary-frequency instantaneous normal modes, the configuration entropy S(c), the distributions of the different-order critical points, and the rate R of escape from a state. Simulation data on f(u)(T) and the density of minima rho(0)(E) in Lennard-Jones and CS2 are fit with the theory, allowing a determination of some model parameters. A universal scaling form for f(u), and a consequent scheme for calculating the mode-coupling temperature T(c) consistently among different materials, is demonstrated. The dependence of the self-diffusion constant D upon R and f(u) is discussed, with the conclusion that D proportional, variant f(u) in deeply supercooled states. The phenomenology of fragile supercooled liquids is interpreted. It is shown that the REM need not have a Kauzmann transition in the relevant temperature range, i.e., above the glass transition.
We investigate a model protein interaction network whose links represent interactions between individual proteins. This network evolves by the functional duplication of proteins, supplemented by random link addition to account for mutations. When link addition is dominant, an infinite-order percolation transition arises as a function of the addition rate. In the opposite limit of high duplication rate, the network exhibits giant structural fluctuations in different realizations. For biologically relevant growth rates, the node degree distribution has an algebraic tail with a peculiar rate dependence for the associated exponent.
We describe here a method for measuring DNA replication and, thus, cell proliferation in slow turnover cells that is suitable for use in humans. The technique is based on the incorporation of (2)H(2)O into the deoxyribose (dR) moiety of purine deoxyribonucleotides in dividing cells. For initial validation, rodents were administered 4% (2)H(2)O in drinking water. The proliferation rate of mammary epithelial cells in mice was 2.9% per day and increased 5-fold during pregnancy. Administration of estradiol pellets (0-200 microg) to ovariectomized rats increased mammary epithelial cell proliferation, according to a dose-response relationship up to the 100 microg dose. Similarly, proliferation of colon epithelial cells was stimulated in a dose-response manner by dietary cholic acid in rats. Bromodeoxyuridine labeling correlated with the (2)H(2)O results. Proliferation of slow turnover cells was then measured. Vascular smooth muscle cells isolated from mouse aorta divided with a half-life in the range of 270-400 days and die-away values after (2)H(2)O wash-out confirmed these slow turnover rates. The proliferation rate of an adipocyte-enriched fraction from mouse adipose tissue depots was 1-1.5% new cells per day, whereas obese ad libitum-fed obob mice exhibited markedly higher fractional and absolute proliferation rates. In humans, stable long-term (2)H(2)O enrichments in body water were achieved by daily (2)H(2)O intake, without toxicities. Labeled dR from fully turned-over blood cells (monocytes or granulocytes) exhibited a consistent amplification factor relative to body (2)H(2)O enrichment ( approximately 3.5-fold). The fraction of newly divided naive-phenotype T cells after 9 weeks of labeling with (2)H(2)O was 0.056 (CD4(+)) and 0.043 (CD8(+)) (replacement rate <0.1% per day). In summary, (2)H(2)O labeling of dR in DNA allows safe, convenient, reproducible, and inexpensive measurement of cell proliferation in humans and experimental animals and is well suited for slow turnover cells.
Guided-wave single-mode propagation of sub-ps terahertz (THz) pulses in a plastic photonic crystal fibre has been experimentally demonstrated. The plastic photonic crystal fibre (PPCF) is fabricated from high-density polyethylene tubes and filaments. The fibre exhibits low loss and relatively low dispersive propagation of THz pulses within the experimental bandwidth of 0.1-3 THz. Such PPCFs have the promise of low loss, mechanically flexible interconnect channels for compact THz devices and systems.