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Biomedical subjects

S Park

Publications and source records attributed to S Park.

At least 127 records · Page 7Linked to original sources
PubMed2001

Mobility shift assay of calcium-binding proteins of mouse epididymal spermatozoa.

The calcium-binding proteins (CBPs) of mouse epididymal spermatozoa were analysed by mobility changes in the presence of added Ca2+ in two-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The expression patterns of relatively high molecular weight CBPs (Mr > 20 kDa) were different between caput and cauda epididymal spermatozoa. There was a constitutive expression of low molecular weight CBPs (Mr < 20 kDa) regardless of the epididymal region. Most of the CBPs disappeared after the acrosome reaction (AR) induced by Ca2+ ionophore A23187, suggesting that they originated from the acrosome and/or the plasma membrane overlaying the acrosome. Taken together, it can be suggested that changes in CBPs of spermatozoa are important features of sperm maturation during epididymal transit, and that they may be related to the fertilizing ability of mouse epididymal spermatozoa.

Acrosome Reaction↗
PubMed2001

Desflurane pharmacokinetics during cardiopulmonary bypass.

OBJECTIVE: To describe the washin and washout of desflurane when first administered during cardiopulmonary bypass (CPB) for cardiac surgery. DESIGN: A single-arm prospective study. SETTING: University-affiliated hospital operating room. PARTICIPANTS: Ten adult patients presenting for cardiac surgery. INTERVENTIONS: Consenting patients presenting for cardiac surgery received anesthesia with midazolam and fentanyl. Patients were cooled to 32 degrees C on CPB, then desflurane 6% was administered and blood samples drawn repeatedly from the arterial and venous bypass cannulae as well as from the membrane oxygenator inlet and exhaust from 2 to 32 minutes of desflurane administration. Just before rewarming, final (maximum) washin samples were taken. On rewarming, desflurane was discontinued, and blood and gas samples were taken 2 to 24 minutes thereafter. MEASUREMENTS AND MAIN RESULTS: CPB time was 116 +/- 10 minutes, and ischemic time was 81 +/- 6 minutes. Mean pump flow was 4.49 +/- 0.03 L/min, and mean arterial pressure was 70.1 +/- 1 mmHg during the study period. Arterial washin of desflurane was initially rapid; arterial concentrations reached 50% of administered concentrations within 4 minutes, but then slowed, reaching 68% of inspired concentrations at 32 minutes (desflurane concentration 4.0% +/- 0.3%). Arterial washout of desflurane was more rapid; arterial concentrations fell to 18% of the maximum concentration reached within 4 minutes, and only 8% of the maximum arterial concentration was present in blood 20 minutes later. CONCLUSION: Desflurane showed rapid initial washin and washout on CPB when administration was started at 32 degrees C and stopped at time of rewarming.

Aged↗
PubMed2001

Eyelid reconstruction using a hard palate mucoperiosteal graft combined with a V-Y subcutaneously pedicled flap.

Full-thickness eyelid defects after tumour ablation require the reconstruction of two layers, the anterior and posterior lamellae. Eyelids were successfully reconstructed after removal of malignant tumours in four patients using a hard palate mucoperiosteal graft combined with a curved V-Y subcutaneously pedicled flap. Although there have been some reports of hard palate mucosal grafts for reconstruction of the posterior lamella, the graft is not sufficiently rigid to support the reconstructed eyelid without the aid of supporting materials such as cartilage grafts. The hard palate mucoperiosteal graft seems to be rigid enough to support the reconstructed eyelid without the use of cartilage or other supporting materials. The subcutaneously pedicled V-Y advancement flap is useful for reconstruction of the anterior lamella in partial eyelid defects. We used it with a modified curved design to allow easy advancement and to make postoperative scars inconspicuous.

Basal Cell Carcinoma↗
PubMed2001

A case of disseminated Cryptococcosis with skin eruption in a patient with acute leukemia.

Disseminated cryptococcosis is a life-threatening infection caused by Cryptococcus neoformans and cutaneous dissemination occurs in 10-15% of patients. We report a case of a 49-y-old leukemic patient with disseminated cryptococcosis who presented with fever, headache, normal cerebrospinal fluid profile and multiple skin lesions mimicking molluscum contagiosum.

Biopsy↗
PubMed2001

Cleft palate in spondyloepiphyseal dysplasia congenita: case reports.

Cleft palate is one of the common features of spondyloepiphyseal dysplasia congenita (SEDC). However, there are few clinical data about cleft palate in SEDC. We report four patients with cleft palate and SEDC including two with overt cleft palate and two with submucous cleft palate. Our results suggested that SEDC associated with cleft palate should be treated in the same way as solitary cleft palate, and submucous cleft palate may be more common in patients with SEDC than previously appreciated.

Abnormalities, Multiple↗
PubMed2001

Variations of landfill leachate's properties in conjunction with the treatment process.

A study was done on the variations of water quality parameters, in conjunction with the processing steps, installed for the treatment of leachate from a sanitary landfill. The leachate was primarily subjected to biological treatment, composed of anaerobic digestion, aerobic treatment, and rotating biological contact in series. The effluent from the rotating biological contact process was further treated by combination of flocculation-sedimentation and adsorption processes. Finally, it was polished by the reverse osmosis process before discharge. The quality of raw leachate, of influents to and of effluents from the reverse osmosis process was assessed and compared. To determine size--dependent behavior of organic materials, analyses were also made for the fractionated samples through ultrafiltration. The overall treatment efficiency was about 98% for removal of organic materials. Most of the organic materials were in the low molecular weight range. In particular, about 95% of the biological oxygen demand was found to be exerted by the fraction of organic material of which cut -off molecular weight was less than 500. The analysis of molecular weight distribution confirmed that the organic materials resistant to the removal by the treatment process were humic substances, of which cut off molecular weight was greater than 500. The reverse osmosis process showed a high efficiency for removal of high molecular weight constituents. However, the final effluent showed an unexpectedly high oxygen demand.

Adsorption↗
PubMed2001

A new classification of palatal fracture and an algorithm to establish a treatment plan.

Palatal fractures have previously been classified according to the anatomic location of the fracture line, which is helpful for understanding the types of palatal fracture, but which is insufficient for helping the surgeon to decide which fracture to open and how to do so. The purpose of this study was to aid in the establishment of a precise treatment plan by determining the surgical approach and the types of stabilization that should be used for different types of palatal fracture. In a retrospective review of 136 consecutive Le Fort maxillary fractures over 6 years, 18 patients (13.2 percent) with palatal fractures were analyzed. The principle of open reduction and internal fixation was applied to all the patients. In six patients (33 percent), exploration and fixation was done in the palatal surface. Eight patients (44 percent) needed an extended period of immobilization (4 to 6 weeks). No major complications were observed during the follow-up period. An algorithm was devised to help establish a proper treatment plan, and palatal fractures were classified into four types: closed reduction, anterior treatment, anterior and palatal treatment, and combined. The key elements considered in deciding the treatment principle and the classification of a palatal fracture were the possibility of closed reduction, surgical exposure, site of rigid fixation, and stability of fractured segments after rigid fixation. The outcome of reconstruction and the postoperative course differed depending on the type of palatal fracture. This classification scheme provided an easy and simple way to establish a treatment plan and was helpful in learning the treatment principles of palatal fracture.

Adult↗
PubMed2001

New restriction fragment length polymorphism (RFLP) markers for Aspergillus fumigatus.

In this study, we isolated and tested restriction fragment length polymorphism (RFLP) markers for Aspergillus fumigatus based on PCR products amplified by the random amplified polymorphic DNA (RAPD) primer R108. Four DNA fragments, Afd, Af5, Af4, and Af4A, were amplified. Fragments Afd and Af5 were 85% and 88% identical at the DNA level to part of the Afut1 retrotransposon from A. fumigatus. Fragment Af4A is a duplication of fragment Af4 and both showed similarity at the amino acid level with endonucleases from other fungal retrotransposons. We used both RAPD with primer R108 and RFLP assays with Afut1, Afd, and Af4A, to determine the genetic relatedness of clinical isolates of A. fumigatus isolated sequentially from four patients colonized with A. fumigatus. The combination of these different methods suggested that the isolates infecting the four patients were not identical.

Amino Acid Sequence↗
PubMed2001

Prospective study of Candida species in patients at a comprehensive cancer center.

Since most nosocomial systemic yeast infections arise from the endogenous flora of the patient, we prospectively evaluated the species stratification and antifungal susceptibility profile of Candida spp. associated with heavy colonization and systemic infection in patients at Memorial Sloan-Kettering Cancer Center in New York. A total of 349 Candida isolates were obtained from 223 patients during the later half of 1998. Cancer was the most common underlying disease, occurring in 91% of the patients, including 61.8% with organ and 23.7% with hematological malignancies; 4.4% of the patients had AIDS. Candida albicans was the predominant species (67.3%); among 114 non-albicans Candida spp., C. glabrata (45.6%) was the most frequent, followed by C. tropicalis (18.4%), C. parapsilosis (16.6%), and C. krusei (9.6%). The overall resistance to triazole-based agents among all yeast isolates was 9.4 and 10.8% for fluconazole and itraconazole, respectively. A total of 5% of C. albicans strains were resistant to triazole antifungals, whereas 30.8 and 46.2% of C. glabrata strains were resistant to fluconazole (MIC > or = 64 microg/ml) and itraconazole (MIC > or = 1 microg/ml), respectively. A significant association was observed between prior treatment with triazole and isolation of fluconazole-resistant C. albicans (P = 0.005, OR 36), although this relationship was not seen in C. glabrata isolates (P = 0.4). This study reinforces the importance of periodic, prospective surveillance of clinical fungal isolates to determine appropriate prophylactic, empiric, and preemptive antifungal therapy for the highly susceptible patient population.

Antifungal Agents↗
PubMed2001

Cytopathic changes in rat microglial cells induced by pathogenic Acanthamoeba culbertsoni: morphology and cytokine release.

To determine whether pathogenic Acanthamoeba culbertsoni trophozoites and lysate can induce cytopathic changes in primary-culture microglial cells, morphological changes were observed by transmission electron microscopy (TEM). In addition, the secretion of two kinds of cytokines, tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta), from microglial cells was observed. Trophozoites of pathogenic A. culbertsoni made contact with microglial cells and produced digipodia. TEM revealed that microglial cells cocultured with amoebic trophozoites underwent a necrotic process, accompanied by lysis of the cell membrane. TEM of microglial cells cocultured with amoebic lysate showed that the membranes of the small cytoplasmic vacuoles as well as the cell membrane were lysed. The amounts of TNF-alpha secreted from microglial cells cocultured with A. culbertsoni trophozoites or lysate increased at 6 h of incubation. The amounts of IL-1beta secreted from microglial cells cocultured with A. culbertsoni trophozoites at 6 h of incubation was similar to those secreted from the control group, but the amounts decreased during cultivation with A. culbertsoni lysate. These results suggest that pathogenic A. culbertsoni induces the cytopathic effects in primary-culture rat microglial cells, with the effects characterized by necrosis of microglial cells and changes in levels of secretion of TNF-alpha and IL-1beta from microglial cells.

Acanthamoeba↗
PubMed2001

Protection against anthrax lethal toxin challenge by genetic immunization with a plasmid encoding the lethal factor protein.

The ability of genetic vaccination to protect against a lethal challenge of anthrax toxin was evaluated. BALB/c mice were immunized via gene gun inoculation with eucaryotic expression vector plasmids encoding either a fragment of the protective antigen (PA) or a fragment of lethal factor (LF). Plasmid pCLF4 contains the N-terminal region (amino acids [aa] 10 to 254) of Bacillus anthracis LF cloned into the pCI expression plasmid. Plasmid pCPA contains a biologically active portion (aa 175 to 764) of B. anthracis PA cloned into the pCI expression vector. One-micrometer-diameter gold particles were coated with plasmid pCLF4 or pCPA or a 1:1 mixture of both and injected into mice via gene gun (1 microg of plasmid DNA/injection) three times at 2-week intervals. Sera were collected and analyzed for antibody titer as well as antibody isotype. Significantly, titers of antibody to both PA and LF from mice immunized with the combination of pCPA and pCLF4 were four to five times greater than titers from mice immunized with either gene alone. Two weeks following the third and final plasmid DNA boost, all mice were challenged with 5 50% lethal doses of lethal toxin (PA plus LF) injected intravenously into the tail vein. All mice immunized with pCLF4, pCPA, or the combination of both survived the challenge, whereas all unimmunized mice did not survive. These results demonstrate that DNA-based immunization alone can provide protection against a lethal toxin challenge and that DNA immunization against the LF antigen alone provides complete protection.

Animals↗
PubMed2001

Type D retrovirus Gag polyprotein interacts with the cytosolic chaperonin TRiC.

The carboxy terminus-encoding portion of the gag gene of Mason-Pfizer monkey virus (M-PMV), the prototype immunosuppressive primate type D retrovirus, encodes a 36-amino-acid, proline-rich protein domain that, in the mature virion, becomes the p4 capsid protein. The p4 domain has no known role in M-PMV replication. We found that two mutants with premature termination codons that remove half or all of the p4 domain produced lower levels of stable Gag protein and of self-assembled capsids. Interestingly, yeast two-hybrid screening revealed that p4 specifically interacted with TCP-1gamma, a subunit of the chaperonin TRiC (TCP-1 ring complex). TRiC is a cytosolic chaperonin that is known to be involved in both folding and subunit assembly of a variety of cellular proteins. TCP-1gamma also associated with high specificity with the M-PMV pp24/16-p12 domain and human immunodeficiency virus p6. Moreover, in cells, Gag polyprotein associated with the TRiC chaperonin complex and this association depended on ATP hydrolysis. In the p4 truncation mutants, the Gag-TRiC association was significantly reduced. These results strongly suggest that cytosolic chaperonin TRiC is involved in Gag folding and/or capsid assembly. We propose that TRiC associates transiently with nascent M-PMV Gag molecules to assist in their folding. Consequently, properly folded Gag molecules carry out the intermolecular interactions involved in self-assembly of the immature capsid.

Capsid↗
PubMed2001

The EphA8 receptor regulates integrin activity through p110gamma phosphatidylinositol-3 kinase in a tyrosine kinase activity-independent manner.

Recent genetic studies suggest that ephrins may function in a kinase-independent Eph receptor pathway. Here we report that expression of EphA8 in either NIH 3T3 or HEK293 cells enhanced cell adhesion to fibronectin via alpha(5)beta(1)- or beta(3) integrins. Interestingly, a kinase-inactive EphA8 mutant also markedly promoted cell attachment to fibronectin in these cell lines. Using a panel of EphA8 point mutants, we have demonstrated that EphA8 kinase activity does not correlate with its ability to promote cell attachment to fibronectin. Analysis using EphA8 extracellular and intracellular domain mutants has revealed that enhanced cell adhesion is dependent on ephrin A binding to the extracellular domain and the juxtamembrane segment of the cytoplasmic domain of the receptor. EphA8-promoted adhesion was efficiently inhibited by wortmannin, a phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor. Additionally, we found that EphA8 had associated PI 3-kinase activity and that the p110gamma isoform of PI 3-kinase is associated with EphA8. In vitro binding experiments revealed that the EphA8 juxtamembrane segment was sufficient for the formation of a stable complex with p110gamma. Similar results were obtained in assay using cells stripped of endogenous ephrin A ligands by treatment with preclustered ephrin A5-Fc proteins. In addition, a membrane-targeted lipid kinase-inactive p110gamma mutant was demonstrated to stably associate with EphA8 and suppress EphA8-promoted cell adhesion to fibronectin. Taken together, these results suggest the presence of a novel mechanism by which the EphA8 receptor localizes p110gamma PI 3-kinase to the plasma membrane in a tyrosine kinase-independent fashion, thereby allowing access to lipid substrates to enable the signals required for integrin-mediated cell adhesion.

3T3 Cells↗
PubMed2001

Thyroid-stimulating hormone transcriptionally regulates the thiol-specific antioxidant gene.

Thiol-specific antioxidant (TSA) plays an important role in regulating cell differentiation and proliferation by modulating the hydrogen peroxide (H2O2) mediated responses in a variety of mammalian cells. Thyroid cells are constantly exposed to the actions of reactive oxygen species (ROS), because they produce high levels of H2O2 in response to the physiological action of TSH (thyroid-stimulating hormone). Thyrocytes have several defense mechanisms against ROS, including TSA and SOD (superoxide anion dismutase). Using Northern blot hybridization, we tested the effects of TSH on TSA gene expression in FRTL-5 cells derived from rat thyroids. TSA mRNA expression increased following treatment of cells with TSH at concentrations greater than 10(-9) M. This effect was observed within 6 hours following treatment, and peaked at 8 hours. The effect was blocked by actinomycin D, but not by cycloheximide. The half-life of TSA mRNA was approximately 5.5 hours in the presence or absence of TSH, and that was not affected by TSA mRNA stability. The effects on TSA gene expression were specific to TSH. Other growth factors (e.g., insulin, transferrin and hydrocortisone) did not alter TSA expression. Our results are the first indication that TSH regulates the expression of TSA transcriptionally in thyrocytes.

Animals↗
PubMed2001

endo-Fullerene and doped diamond nanocrystallite-based models of qubits for solid-state quantum computers.

Models of encapsulated nuclear spin 1/2 1H and 31P atoms in fullerene and diamond nanocrystallite, respectively, are proposed and examined with an ab initio local density functional method for possible applications as single quantum bits (qubits) in solid-state quantum computers. A 1H atom encapsulated in a fully deuterated fullerene, C20D20, forms the first model system and ab initio calculation shows that the 1H atom is stable in its atomic state at the center of the fullerene with a barrier of about 1 eV to escape. A 31P atom positioned at the center of a diamond nanocrystallite is the second model system, and 31P atom is found to be stable at the substitutional site relative to interstitial sites by 15 eV. Vacancy formation energy is 6 eV in diamond, so the substitutional 31P atom will be stable against diffusion during the formation mechanisms within the nanocrystallite. The coupling between the nuclear spin and the weakly bound (valance) donor electron in both systems is found to be suitable for single qubit applications, whereas the spatial distributions of (valance) donor electron wave functions are found to be preferentially spread along certain lattice directions, facilitating two or more qubit applications. The feasibility of the fabrication pathways for both model solid-state qubit systems within practical quantum computers is discussed within the context of our proposed solid-state qubits.

Computer Simulation↗