Biomedical subjects

D Kim

Publications and source records attributed to D Kim.

At least 253 records · Page 14Linked to original sources

PubMed1998

Cell-division-cycle defects associated with fission yeast pre-mRNA splicing mutants.

We have isolated six new pre-mRNA splicing mutants (prp) from a collection of temperature-sensitive (ts-) Schizosaccharomyces pombe strains. The prp mutants are defective in the splicing of both messenger RNA and U6 small nuclear RNA precursors. A single recessive mutation is responsible for both the ts- growth and the splicing phenotypes in each of the prp mutants. The six prp mutations are unlinked and fall into separate complementation groups. Two are allelic with the previously described prp3 and prp4 mutations; the remaining four define the new alleles prp5-1, prp6-1, prp7-1, and prp9-1. The six mutants exhibit three splicing phenotypes: accumulation of unspliced precursor at the restrictive but not at the permissive temperature; accumulation of unspliced precursor at both the permissive and restrictive temperatures; and accumulation of unspliced precursor, the intron-exon lariat intermediate, and the intron lariat final product. In addition to their aberrant splicing phenotypes, the prp5-1 and prp6-1 mutants express classical cell-division-cycle defects, while prp7-1 exhibits an unusual hyphal morphology. These results suggest a connection between pre-mRNA splicing and the control of cell division in fission yeast.

Cell Cycle↗

PubMed1998

Expression of Bfl-1 in normal and tumor tissues: Bfl-1 overexpression in cancer is attributable to its preferential expression in infiltrating inflammatory cells.

Bfl-1, a member of the Bcl-2 gene family, blocks p53-mediated apoptosis and has oncogenic transforming activity. In normal tissues, the transcript of Bfl-1 is expressed abundantly in bone marrow and at a low level in several other tissues. In previous experiments, elevated expression of Bfl-1 was observed by Northern analysis of stomach cancer samples. To study the role of Bfl-1 in normal cell development and in tumorigenesis, we have analyzed the expression of Bfl-1 in normal and tumor tissues by the in situ hybridization technique. The Bfl-1 transcript was detected in the white pulp of the spleen and in the germinal center of lymphatic tissues. In tumor tissues, its expression was preferentially detected in infiltrating inflammatory cells rather than in cancer cells, suggesting that Bfl-1 is not involved in tumorigenesis.

Colonic Neoplasms↗

PubMed1998

Inhibition of immediate type allergic reactions by the aqueous extract of Kum-Hwang-San.

We studied the effect of aqueous extract of Kum-Hwang-San (KHS) on mast cell-mediated immediate type allergic reactions. KHS (1-100 microg/site) inhibited concentration-dependently mast cell-dependent ear swelling response induced by compound 48/80 (200 microg/site) in mice by both topical and intradermal application. KHS (0.1-100 microg/site) inhibited concentration-dependently passive cutaneous anaphylaxis induced by anti-dinitrophenyl (DNP) IgE in rats by both topical and intradermal application. KHS also inhibited concentration-dependently the histamine release from the rat peritoneal mast cells (RPMC) by compound 48/80 and anti-DNP IgE. Moreover, KHS had a significant inhibitory effect on anti-DNP IgE-induced tumor necrosis factor-alpha (TNF-alpha) secretion from RPMC. These results indicate that KHS inhibits immediate type allergic reactions by inhibition of histamine release and TNF-alpha secretion from mast cells in vivo and in vitro.

Animals↗

PubMed1998

Development of effective hydrogen sulphide removing equipment using Thiobacillus sp.IW.

Hydrogen sulphide is one of the commonest odours emitted by chemical plants. To remove the hydrogen sulphide biologically, a three phase fluidised bed bioreactor was used in which Thiobacillus sp.IW was immobilised on activated carbon. The optimum operating conditions of the bioreactor were 30 degrees C, pH7, aspect ratio (L/D) = 1 and at these conditions, the system removed over 94% of the hydrogen sulphide in the concentration range of 100-200 ppm and flow rate of 1.0-2.0 litre min(-1). From the upset and recovery test, the system proved stable within the moderate inlet concentration changes investigated.

Journal Article↗

PubMed1998

On becoming a parasite: evaluating the role of wall oxidases in parasitic plant development.

BACKGROUND: The temporal and spatial control of the transition from vegetative to parasitic growth is critical to any parasite, but is essential to the sessile parasitic plants. It has been proposed that this transition in Striga spp. is controlled simply by an exuded oxidase that converts host cell-surface phenols into benzoquinones which act as developmental signals that mediate the transition. An understanding of this mechanism may identify the critical molecular events that made possible the evolution of parasitism in plants. RESULTS: PoxA and PoxB are identified as the only apoplastic phenol oxidases in Striga asiatica seedlings, and the genes encoding them have been cloned and sequenced. These peroxidase enzymes are capable of oxidizing the 60 known inducing phenols into a small set of benzoquinones, and it is these quinones that induce parasitic development. Analysis of the reaction requirements and comparisons to host enzymes, however, lead us to argue that PoxA and PoxB are not necessary for host recognition. CONCLUSIONS: A new model is proposed where constitutive production of an activated oxygen species (in the case of Striga, H2O2) mediates host recognition. This strategy would allow a parasite to exploit abundant host enzymes to produce the diffusible recognition signals by converting a standard host defense into a parasitic offense.

Amino Acid Sequence↗

PubMed1998

Parotid gland swelling in HIV diffuse infiltrative CD8 lymphocytosis syndrome.

HIV can affect salivary gland tissue. Parotid swellings have been observed in a subset of patients who are HIV-positive; the swellings are the result of a condition that has been termed diffuse infiltrative CD8 lymphocytosis syndrome. Initially the glandular enlargement results from a massive CD8 cell lymphoproliferation, but with time lymphoepithelial cysts become manifest. Two case reports are presented to illustrate this progression of diffuse infiltrative CD8 lymphocytosis.

Adult↗

PubMed1998

A rearrangement of the CDD gene at the 5' UTR produces two types of transcripts that contain a natural antisense region.

In order to study the regulatory region for transcription, the genomic DNA of the human CDD gene was cloned and analyzed. In contrast to previously reported CDD cDNA sequence, the sequence of the isolated genomic clone was rearranged at the 5' untranslated region (UTR) by a 30 bp inversion and a 57 bp insertion. Polymerase chain reaction (PCR) of chromosomal DNA and mRNA, and sequencing analysis of the PCR products revealed that sequences corresponding to both the genomic clone and the cDNA clone were present in the chromosomal DNA and were also transcribed into mRNA. Because of the 30 base inversion, the two types of CDD transcripts contain antisense sequences in their 5' UTR. Their role in the regulation of CDD expression is discussed.

5' Untranslated Regions↗

PubMed1998

A randomized, prospective, comparative study of manual and automated renal biopsies.

A percutaneous renal biopsy can be performed in several ways, including using a spring-loaded biopsy gun. As this form of renal biopsy has become more popular, a controversy has developed regarding tissue adequacy and the incidence of complications. To compare these two aspects in an automated biopsy and a manual biopsy, we studied 166 patients assigned to one of the two renal biopsy methods. In a randomized, prospective manner from June 1994 until February 1997, group 1 (67 patients) received a 14 G Tru-cut needle (Baxter, Deerfield, IL) manual biopsy while group 2 (99 patients) received an 18 G automated gun biopsy. There was no difference in sex, age, hemoglobin level, prothrombin time, partial thromboplastin time, or diastolic and systolic blood pressure prebiopsy in groups I and II. Indications for biopsy were proteinuria (38%), proteinuria accompanied by hematuria (31.3%), acute renal failure (9.6%), lupus nephropathy (9.6%), chronic renal failure (6%), and hematuria only (5.4%). In group I, the number of cores was 1.88 +/- 0.56, the glomeruli obtained were 27.3 +/- 13.8, and the number of glomeruli per core were 15.3 +/- 8.4. In group II, the values were 2.37 +/- 0.88, 20.7 +/- 11.1, and 9.95 +/- 6.9, respectively. These results showed a statistically significant difference (P < 0.05). In all cases, pathological diagnosis was possible. The histology showed IgA nephropathy in 25.9%, minimal change disease in 16.3%, lupus nephritis in 11.4%, membranous glomerulonephropathy in 9.3%, membranoproliferative glomerulonephritis in 5.4%, and others. The incidence of postbiopsy hematoma was marginally greater in group I (22.3% v 11.1%) and the area of perirenal hematoma shown on ultrasound 24 hours postbiopsy was larger in group I, as well (848 +/- 623 mm2 v 338 +/- 260 mm2). Hematocrit levels before and after biopsy showed a significant difference (34.9% +/- 7.9% and 34.0% +/- 7.6%, respectively; P < 0.05) in group I, but no significant difference was observed in group II (35.1% +/- 7.0% and 34.7% +/- 6.9%). Both techniques rendered adequate tissue sampling, but the extent of bleeding was more severe with the manual 14 G Tru-cut needle biopsy.

Acute Kidney Injury↗

PubMed1998

Regulation of programmed cell death following T cell activation in vivo.

Activation of T cell hybridomas in vitro induces rapid Fas-Fas ligand (FasL)-mediated programmed cell death (apoptosis). In contrast, T cells activated by antigen or superantigen in vivo undergo a population expansion and then decline due to Fas-FasL-mediated activation-induced apoptosis (AIA). We asked how T cells activated by antigen in vivo proliferated before undergoing apoptosis. Two possibilities were analyzed: either (i) the apoptosis program was not 'turned on' or (ii) was 'blocked' during the period of cellular proliferation in vivo. Data presented in this manuscript support the second of these possibilities. CD4+ T cells activated in vivo were resistant to anti-fas-mediated apoptosis until 48 h following staphylococcal enterotoxin B (SEB) administration, despite the fact that activated proliferating T cells expressed high levels of Fas (CD95) antigen and many 'apoptosis genes' were induced within 24 h of SEB administration. The analysis of the expression patterns of 'apoptosis genes' during the T cell activation further suggested that temporal blockade of AIA may be due to the induction of apoptosis-preventing genes, such as bag-1.

Animals↗

PubMed1998

Biorhythmic influences on functional capacity of human muscle and physiological responses.

UNLABELLED: Previously, this laboratory has demonstrated that exhaustive aerobic exercise performance is not subject to significant chronobiological variation between 0800 and 2000 h, but certain physiological responses to maximal aerobic effort do fluctuate significantly within that time frame. PURPOSE: The purpose of the present investigation was to determine whether muscle performance, and selected physiological responses to resistance exercise, was significantly influenced by time of day effects. METHODS: Ten healthy, but untrained, men (21.1+/-0.6 yr, mean +/- SE) volunteered to participate in the study. In a balanced and randomized study design, each subject performed resistance exercise protocols on an isokinetic dynamometer with maximal effort at 0800 h, 1200 h, 1600 h, and 2000 h. Selected physiological and hormonal data were recorded before and immediately following the exercise stimulus. RESULTS: The data demonstrated significant chronobiological oscillation in peak torque, average power, maximal work in a single repetition, and total work per set. Interestingly, this oscillation was manifested only at the fastest velocities of limb movement utilized. Pre- and postexercise rectal temperature exhibited significant time of day fluctuation, as did postexercise blood pressure. Plasma levels of testosterone and cortisol also displayed significant biorhythmicity under both pre- and postexercise conditions. However, exercise-induced responses (pre- to postexercise differences) of those steroid hormones did not exhibit significant biorythmic variation. Although plasma concentrations of both testosterone and cortisol were highest at 0800 h, testosterone to cortisol ratios were greatest at 2000 h. CONCLUSIONS: In summary, these data suggest that maximal muscle performance does vary within the segment of the day when exercise typically occurs (0800-2000 h) but that this variation is specific to speed of movement.

Adult↗

PubMed1998

Naïve and memory CD4 T cells differ in their susceptibilities to human immunodeficiency virus type 1 infection following CD28 costimulation: implicatip6s for transmission and pathogenesis.

In vitro evidence suggests that memory CD4(+) cells are preferentially infected by human immunodeficiency virus type 1 (HIV-1), yet studies of HIV-1-infected individuals have failed to detect preferential memory cell depletion. To explore this paradox, we stimulated CD45RA+ CD4(+) (naïve) and CD45RO+ CD4(+) (memory) cells with antibodies to CD3 and CD28 and infected them with either CCR5-dependent (R5) or CXCR4-dependent (X4) HIV-1 isolates. Naïve CD4(+) cells supported less X4 HIV replication than their memory counterparts. However, naïve cells were susceptible to R5 viral infection, while memory cells remained resistant to infection and viral replication. As with the unseparated cells, mixing the naïve and memory cells prior to infection resulted in cells resistant to R5 infection and highly susceptible to X4 infection. While both naïve and memory CD4(+) subsets downregulated CCR5 expression in response to CD28 costimulation, only the memory cells produced high levels of the beta-chemokines RANTES, MIP-1alpha, and MIP-1beta upon stimulation. Neutralization of these beta-chemokines rendered memory CD4(+) cells highly sensitive to infection with R5 HIV-1 isolates, indicating that downregulation of CCR5 is not sufficient to mediate complete protection from CCR5 strains of HIV-1. These results indicate that susceptibility to R5 HIV-1 isolates is determined not only by the level of CCR5 expression but also by the balance of CCR5 expression and beta-chemokine production. Furthermore, our results suggest a model of HIV-1 transmission and pathogenesis in which naïve rather than memory CD4(+) T cells serve as the targets for early rounds of HIV-1 replication.

ADP-ribosyl Cyclase↗

PubMed1998

Inhibition of ATP-induced increase in muscarinic K+ current by trypsin, alkaline pH, and anions.

In atrial cells, the open probability of G protein-activated ACh-sensitive K+ (KACh) channels can be increased approximately fivefold by intracellular ATP (ATPi). Using inside-out patches, we examined how proteases, changes in intracellular pH, and different anions affect G protein-mediated activation and ATP-induced stimulation of the KACh channel. Treatment with trypsin (0.5 mg/ml) removed the GTP dependence of the KACh channel and abolished the ATP-induced stimulation. Intracellular GTP activated KACh channels at all intracellular pH values tested (6.0-8.0), with the concentration at which half-maximal activation (K1/2) occurred ranging from 0.3 (pH 8.0) to 6.7 (pH 6.0) microM. However, the ATPi-induced increase in KACh channel activity was inhibited at pH 8. 0 (K1/2 = pH 7.4). All anions tested except sulfate, phosphate, fluoride, and iodide supported GTP-induced activation. Of the anions that supported GTP-induced activation, only citrate blocked the ATP-induced stimulation of the KACh channel. These results indicate that the GTP- and ATP-mediated effects on the KACh channel use separate signaling pathways. The ATP-mediated effect involves a trypsin- and pH-sensitive mechanism.

Acetylcholine↗

PubMed1998

Peritoneal dialysis-associated peritonitis caused by Alcaligenes xylosoxidans.

Despite significant progress to decrease its incidence, peritonitis remains the main source of morbidity and treatment failure in patients on continuous ambulatory peritoneal dialysis (CAPD). The majority of cases of peritonitis result from infection with aerobic gram-positive (Staphylococcus epidermidis and Staphylococcus aureus), or gram-negative organisms. Less common organisms that are also reported include anaerobic bacteria, fungi, and mycobacteria, which collectively account for less than 10% of isolates cultured. We report a case of peritoneal dialysis-associated peritonitis, and review the literature on peritonitis caused by Alcaligenes species. Alcaligenes xylosoxidans is a nonfermenting gram-negative rod and opportunistic pathogen that is motile with peritrichous flagella. The clinical features and microbiological data of our case, as well as the other previously reported cases of peritonitis caused by Alcaligenes species show no particular pattern of peritoneal dialysate cell count. However, the rate of recurrence of peritonitis is characteristically high. The cause of such a high rate of recurrence of peritonitis is probably a reflection of the predilection of Alcaligenes species to cause infection in the 'sicker' patients, and the almost universal resistance of this species to most antimicrobial agents. We, therefore, recommend that catheter removal be undertaken as early as the identification of the organism is made. Whether patients should be allowed to return to CAPD after recovery is a more difficult question. We suggest that a reevaluation of the patient's overall status be undertaken, including personal hygiene, exchange technique, presence of diabetes mellitus, malnutrition, and/or other factors that may render the patient more prone to infection with opportunistic pathogens.

Alcaligenes↗

PubMed1998

Research-related burnout among faculty in higher education.

We investigated the effects of intrinsic motivation to do research and perceived lack of rewards contingent on doing research on burnout or disenchantment from research. Findings, based on a survey of 328 faculty at a major university, indicate that these two variables account for 74% and 81% of the variance in scores on a scale relating to burnout among 260 tenured and 68 untenured professors, respectively. The effect of perceived lack of rewards contingent on doing research on burnout was moderated by the tenure status.

Attitude↗

PubMed1998

Management and results of sciatic nerve injuries: a 24-year experience.

OBJECT: The purpose of this retrospective clinical study was to present results and provide management guidelines for various types of sciatic injuries. METHODS: Over a 24-year period, 380 patients with sciatic nerve injuries were managed. In 230 patients (60%), the injury was at the buttock level, with injection injuries comprising more than half of these cases. Thigh-level sciatic injury was evaluated in 150 cases (40%) and was usually secondary to one of four main causes: 1) gunshot wound; 2) femur fracture; 3) laceration; or 4) contusion. Patients with partial deficits uncomplicated by severe pain or with significant spontaneous recovery or late referral were managed medically. Surgical exploration was not indicated in 23% of injuries at the thigh level and almost 50% of those at the buttock level. Most of these patients achieved partial but good spontaneous recovery, especially in the tibial division distribution. Surgical intervention was required for more complete and persistent deficits in either the tibial or peroneal distribution. Divisions of the sciatic nerve were split apart and evaluated independently. Management was guided by nerve action potential (NAP) recordings, which indicated whether neurolysis or resection of the lesion was required. Repair was then made by using sutures or more frequently by graft placement. In most cases in which neurolysis was performed because a positive NAP was recorded distal to the lesion, useful function was found in the peroneal distribution. Unfortunately, significant recovery occurred in only 36% of patients who received suture or graft repairs of the peroneal division. Good-to-excellent outcome was common for the tibial division, even in cases in which repair was proximal and required lengthy grafts. The relatively favorable recovery of tibial as opposed to peroneal divisions of the sciatic nerve occurred regardless of the level or mechanism of injury. CONCLUSIONS: Surgical exploration and, when necessary, repair of sciatic nerve injuries is worthwhile in selected cases.

Action Potentials↗

PubMed1998

Hemodynamic effects of the geometric dimensions of graft vessels in coronary artery bypass graft models.

The objectives of this investigation are to evaluate the rheologic properties in atherosclerotic disease treated with the various coronary artery bypass graft (CABG) models by numerical analysis, we used four different CABG models for the assessment of spatial fluctuation in wall shear stress, pressure variation and mass flow rate with Carreau model and Navier-Stokes equation. Wall shear stress was higher in a naturally tapered model (model 1) and a constant (non-tapered) diameter of the graft vessel the same as the distal LAD (model 4) than in others. Pressure variation along the native coronary artery and graft vessels was higher in a model 4, model 1 than in a reverse tapering model (model 2) and a constant diameter of the graft vessel the same as the proximal LAD (model 3). The mass flow rate of the distal part (kg/sec,.m(o)) was the highest in model 3. This study suggests that in vitro spatial simulation following CABG revealed that small caliber or tapered graft vessels have adverse hemodynamic effects on the native and graft vessels. By this technique it is possible to simulate the optimal distribution of local hemodynamic variables in patients treated with CABG, also to minimize the degeneration of graft vessel.

Computer Simulation↗

PubMed1998

Ultrastructural changes of the internal elastic lamina in experimental hypercholesterolemic porcine coronary arteries.

The internal elastic lamina (IEL) serves as a barrier for cells and macromolecules between the intima and media in the vascular wall. We evaluated the morphological changes and quantitative assessments of the IEL architecture in the coronary circulation of pigs fed with a high cholesterol diet. Transmission electron microscopy (TEM) analysis of the IEL from hypercholesterolemic coronary arteries revealed fragmentation of the IEL associated with a decrease in the thickness. Confocal microscopy and scanning electron microscopy (SEM) revealed an altered pattern characterized by a large oval fenestration in the IEL of hypercholesterolemic vessels. Morphometric analysis of confocal microscopy images demonstrated that the IEL of cholesterol-fed animals were characterized by an increase in the minor diameter of the fenestrae (2.16+/-0.04 microm vs 3.32+/-0.06 microm, p=0.003) and a decrease in the fenestrae density (22,333+/-1,334/mm2 vs 17,552+/-931/mm2, p=0.015) compared to controls. The percentage of the IEL area covered by the fenestrae correlated with the intimal thickness (r=0.79, p=0.004). The immunoreactivity for matrix metalloproteinase-3 (MMP-3) increased in cholesterol-fed coronary arteries, predominantly in the neointima. This study demonstrates experimental hypercholesterolemia induced ultrastructural changes of the IEL in the coronary circulation. The IEL may play an important role in the development of structural changes which characterize the early phase of coronary atherosclerosis.

Animals↗

PubMed1998

Computed numerical analysis of the biomechanical effects on coronary atherogenesis using human hemodynamic and dimensional variables.

The objectives of this investigation were to evaluate biomechanical factors in the atherosclerotic process using human in vivo hemodynamic parameters and computed numerical simulation qualitatively and quantitatively. The three-dimensional spatial patterns of steady and pulsatile flows in the left coronary artery were simulated, using a finite volume method. Coronary angiogram and Doppler ultrasound measurement of the proximal left coronary flow velocity were performed in humans. Inlet wave velocity distribution obtained from in vivo data of the intravascular Doppler study allowed for input of in vitro numerical simulation. Hemodynamic variables, such as flow velocity, pressure and shear stress of the left anterior descending coronary bifurcation site were calculated. We found that there were spatial fluctuation of flow-velocity and recirculation areas at the curved outer wall of the left anterior descending coronary artery, which were due to the differences of flow-velocity and shear stress, especially during the declaration phase of pulsatile flow. This study suggests that rheologic properties may be a part of the atherogenic process in the coronary bifurcated and curved areas.

Biomechanical Phenomena↗