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Biomedical subjects

P Kim

Publications and source records attributed to P Kim.

At least 19 recordsLinked to original sources
PubMed2006

Landau-level splitting in graphene in high magnetic fields.

The quantum Hall (QH) effect in two-dimensional electrons and holes in high quality graphene samples is studied in strong magnetic fields up to 45 T. QH plateaus at filling factors nu = 0, +/-1, +/-4 are discovered at magnetic fields B > 20 T, indicating the lifting of the fourfold degeneracy of the previously observed QH states at nu = +/-4(absolute value(n) + 1/2), where n is the Landau-level index. In particular, the presence of the nu = 0, +/-1 QH plateaus indicates that the Landau level at the charge neutral Dirac point splits into four sublevels, lifting sublattice and spin degeneracy. The QH effect at nu = +/-4 is investigated in a tilted magnetic field and can be attributed to lifting of the spin degeneracy of the n = 1 Landau level.

Journal Article↗
PubMed2005

Case-controlled clinical and histopathological study of conjunctivochalasis.

BACKGROUND/AIMS: Conjunctivochalasis, a secondary cause of the watery eye, is frequently seen in the older age group as an elevation of the bulbar conjunctiva lying along the lateral or central lower lid margin. A prospective, interventional, case-controlled clinical and histopathological study was conducted. The relevant features of 18 patients (29 eyes) who had their conjunctivochalasis resected as part of the surgical management of their watery eye syndrome were examined. In the control group, tissue was obtained from an age matched series of 24 normal subjects undergoing routine cataract surgery. METHODS: 24 controls (24 specimens) and 18 patients (29 specimens) had conjunctival strip biopsies, taken from the usual lid margin level bulbar conjunctiva in line with the inferior limbus (controls), and the clinically apparent conjunctivochalasis (patients). These were submitted for histological study. RESULTS: 23 of 24 control sections demonstrated normal conjunctival variation. Four of 29 patient specimens demonstrated a chronic non-granulomatous conjunctivitis, while three eyes of the patient group (two patients) demonstrated features of elastosis. Of the four patients who had the inflammatory infiltrates, three had functional nasolacrimal duct obstructions (FNLDOs) and one had a primary acquired nasolacrimal duct obstruction (PANDO). Of the two patients who had elastosis, one had an FNLDO and the other had normal lacrimal drainage and was Jones 1 positive. CONCLUSION: Six of 18 patients--that is, seven of 29 specimens of conjunctivochalasis demonstrated signs of elastosis or of chronic non-granulomatous inflammation. Clinically, patients had a spectrum of aetiologies of their watery eye syndrome.

Aged↗
PubMed2004

Transforming growth factor beta and monocyte chemotactic protein-1 are elevated in cerebrospinal fluid of immunocompromised patients with HIV-1 infection.

Monocyte infiltration of the brain is central to the pathogenesis of HIV-1 encephalitis. The cytokines promoting recruitment of monocytes into the central nervous system during HIV-1 infection are not established. In this study, we evaluated human cerebrospinal fluid from patients with HIV-1 infection for transforming growth factor beta1 (TGFbeta1) and monocyte chemotactic protein-1 (MCP-1) using a quantitative sandwich enzyme-linked immunoassays. Cytokine levels were compared to those from patients with multiple sclerosis and normal controls. In cerebrospinal fluid of patients with HIV-1 infection and CD4<500 cells/mm3, both TGFbeta1 and MCP-1 were significantly elevated compared to those with CD4>500 cells/mm3, multiple sclerosis, and controls.

CD4 Lymphocyte Count↗
PubMed2002

Combination chemotherapy using carboplatin (JM-8) and etoposide (JET therapy) for recurrent malignant gliomas: a phase II study.

BACKGROUND: To study efficacy and safety of chemotherapy using carboplatin (JM-8) and etoposide ("JET" therapy) for the treatment of recurrent malignant glioma, a phase II study was conducted. Tumour control, survival time, and toxicity/side effects were assessed in patients with recurrent malignant glioma which failed to respond to a postoperative combined auxiliary therapy comprising of IFN-beta, ACNU and radiation. METHODS: Twenty-eight patients, fourteen with anaplastic astrocytoma (AA) and fourteen with glioblastoma (GB) were included in this study. The JET regimen consists of the intravenous administration of carboplatin (300 mg/m(2)) on day 1 and etoposide (60 mg/m(2)) on day 1 to 5, repeated every 6 weeks. FINDINGS: Following the therapy, we observed partial response (PR) in five (36%) of 14 patients with AA and two (14%) of 14 with GB, and stabilization of the disease (SD) in six (43%) in each group. The mean survival/survival after recurrence was 51 months/25 months in the AA group, and 17/9 in the GB group. INTERPRETATIONS: These results compare favorably with the natural course of recurrent malignant glioma. JET shows signs of efficacy in patients with recurrent malignant glioma, and a randomized trial comparing it to standard therapy is warranted.

Adolescent↗
PubMed2001

The EGL-3 proprotein convertase regulates mechanosensory responses of Caenorhabditis elegans.

Neuroactive peptides are packaged as proproteins into dense core vesicles or secretory granules, where they are cleaved at dibasic residues by copackaged proprotein convertases. We show here that the Caenorhabditis elegans egl-3 gene encodes a protein that is 57% identical to mouse proprotein convertase type 2 (PC2), and we provide evidence that this convertase regulates mechanosensory responses. Nose touch sensitivity (mediated by ASH sensory neurons) is defective in mutants lacking GLR-1 glutamate receptors (GluRs); however, mutations eliminating the egl-3 PC2 restored nose touch sensitivity to glr-1 GluR mutants. By contrast, body touch sensitivity (mediated by the touch cells) is greatly diminished in egl-3 PC2 mutants. Taken together, these results suggest that egl-3 PC2-processed peptides normally regulate the responsiveness of C. elegans to mechanical stimuli.

Animals↗
PubMed2001

Comparing tandem repeats and multiple antigenic peptides as the antigens to detect antibodies by enzyme immunoassay.

Short synthetic peptides are useful alternatives to whole lysate or recombinant proteins as the antigens used for serodiagnosis of bacterial or viral infections. However, certain known antigenic peptides displayed low seroreactivities in direct enzyme immunoassay. This was believed to be due to the low coating efficiency, a constrained orientation, or loss of flexibility required for optimal antibody binding. Using a model peptide system derived from the V3-loop of HIV-1 gp120, we demonstrated that low antigenicity could be overcome by using either tandem repeats (TR) or multiple antigenic peptides (MAPs) which contained the same amino acid sequence as the monomeric peptide. In our model system, a four-branch MAP was a better choice compared to the tandem repeats because of the MAP's slightly higher sensitivity and lower cost of production.

Amino Acid Sequence↗
PubMed2001

Thermal transport measurements of individual multiwalled nanotubes.

The thermal conductivity and thermoelectric power of a single carbon nanotube were measured using a microfabricated suspended device. The observed thermal conductivity is more than 3000 W/K m at room temperature, which is 2 orders of magnitude higher than the estimation from previous experiments that used macroscopic mat samples. The temperature dependence of the thermal conductivity of nanotubes exhibits a peak at 320 K due to the onset of umklapp phonon scattering. The measured thermoelectric power shows linear temperature dependence with a value of 80 microV/K at room temperature.

Journal Article↗
PubMed2001

The discovery of sulfonylated dipeptides as potent VLA-4 antagonists.

Directed screening of a carboxylic acid-containing combinatorial library led to the discovery of potent inhibitors of the integrin VLA-4. Subsequent optimization by solid-phase synthesis afforded a series of sulfonylated dipeptide inhibitors with structural components that when combined in a single hybrid molecule gave a sub-nanomolar inhibitor as a lead for medicinal chemistry. Preliminary metabolic studies led to the discovery of substituted biphenyl derivatives with low picomolar activities. SAR and pharmacokinetic characterization of this series are presented.

Animals↗
PubMed2001

An intraoperative irrigation device using disposable syringes and an extension tube: technical note.

BACKGROUND: The authors present a simple irrigation device used in a microsurgical setting. METHODS: The system consists of a disposable i.v. catheter, an extension tube, a three-way stopcock and two disposable syringes, capable of assembly during a surgical procedure. RESULTS: The length of the handpiece of this device is comparable to other microsurgical tools, which allow both the assistant and the surgeon to grab and irrigate in a coordinated fashion. Clots, tumor contents, and tissue debris are effectively washed away. This tool is particularly useful for lavage of subarachnoid clots during surgery for ruptured intracranial aneurysms, allowing precise anatomic orientation. This device is also practical for cooling tissues adjacent to drilling sites. CONCLUSION: This system is as efficacious as other available self-irrigating microneurosurgical instruments.

Disposable Equipment↗
PubMed2001

Proper management of the rotational vertebral artery occlusion secondary to spondylosis.

A 66-year-old man with cervical spondylosis noticed severe vertigo when turning his head to the right. He underwent subclavian arteriography elsewhere, which showed a block of the contrast medium in the right vertebral artery (VA) at the C5/6 level when the patient turned his head to the right. After referral to our institute, however, postcontrast CT scan revealed an attenuated shadow of the venous plexus around the right VA at the C3/4 level. Repeated selective angiography with rotation of the head after visualization of the entire VA verified the level of obstruction to be at C3/4. Resection of the C4 transverse process through an anterior approach with drilling of the C3/4 spondylotic spur of the uncinate processi completely resolved the arterial impingement and the symptom. When evaluating rotational VA occlusion, dynamic angiography with selective catheterization is essential in determining which level is affected. The postcontrast CT scan is also useful because it suggests the level even without head rotation.

Aged↗
PubMed2001

The utility of the VCS clip for creation of vascular access for hemodialysis: long-term results and intraoperative benefits.

UNLABELLED: The purpose of this study was to compare the effectiveness of the VCS vascular clip approximating system for the creation of hemodialysis access fistulas. 173 new vascular accesses were created, 92 prosthetic grafts and 81 autologous fistulas over a 40-month period. 50 sutured and 42 clipped fistulas comprised the prosthetic graft series, and 33 sutured and 48 clipped cases the autologous series. Risk factors associated with access patency were correlated and the primary patencies compared in the suture versus clipped group. A significant improvement in primary patency was noted for the clipped prosthetic group at all time points studied, with a positive trend also noted for clipped autologous fistulae. CONCLUSIONS: The vascular clipping system (the VCS system) provides both long-term and immediate advantages for vascular access construction. Clips have been used successfully to treat seven consecutive patients with upper extremity arterial steal syndrome without the technical difficulties associated with traditional methods of repair.

Adult↗
PubMed2001

The VACTERL association: lessons from the Sonic hedgehog pathway.

VACTERL represents a non-random association of congenital anomalies in humans of poorly known etiology and pathogenesis. From our mutant analysis of Gli genes, which encode transcription factors mediating Sonic hedgehog (Shh) signal transduction, we observed that defective Shh signaling leads to a spectrum of developmental anomalies in mice strikingly similar to those of VACTERL. In this review, we will discuss the function of the three Gli transcription factors in Shh signaling and mammalian development. We propose that VACTERL could be caused by defective Shh signaling during human embryogenesis and suggest that the Gli mutant mice can serve as useful models for studying the pathogenesis of VACTERL.

Abnormalities, Multiple↗
PubMed2001

Improvement of tagatose conversion rate by genetic evolution of thermostable galactose isomerase.

To enhance the isomerization rate of galactose into tagatose, a thermostable galactose isomerase, which was isolated from bacteria growing in a hot spring, was genetically improved using the error-prone PCR method. From 500 mutant clones, a clone showing improved conversion activity was selected. The sequence of the selected clone had five amino acid changes: His(228)-->Asp, Gly(384)-->Asp, Ser(393)-->Thr, Lys(428)-->Asn and Asp(475)-->Lys. The improved galactose isomerase had an 11-fold higher reaction rate than the original.

Aldose-Ketose Isomerases↗
PubMed2001

Sudden unconsciousness during a lesser occipital nerve block in a patient with the occipital bone defect.

Occipital nerve block is usually considered to be a very simple and safe regional anaesthetic technique. We describe a case of sudden unconsciousness during a lesser occipital nerve block in a patient with an occipital bone defect. A 63-year-old man complained of headache, which was localized to the right occipital region. A right lesser occipital nerve block with a local anaesthetic was performed for treatment. During the lesser occipital nerve block, the patient suddenly became disturbed and lost consciousness. Two hours after the incident, the patient was fully awake without neurological sequelae. He had previously undergone a microvascular decompression for right trigeminal neuralgia. The patient had a bone defect following craniotomy. We believed that the loss of consciousness during lesser nerve block may be due to a subarachnoid injection. Occipital nerve block is relatively contraindicated in the presence of a bone defect.

Anesthetics, Local↗
PubMed2001

Intrahepatic nuclear factor-kappa B activity and alpha 1-acid glycoprotein transcription do not predict outcome after cecal ligation and puncture in the rat.

OBJECTIVE: Sepsis is the leading cause of death in critically ill surgical patients. Septic hepatic dysfunction, an important determinant of outcome, is poorly understood but includes inappropriate transcriptional down-regulation. This may be modulated by proinflammatory cytokines. We hypothesized that intrahepatic changes in tumor necrosis factor (TNF)/interleukin (IL)-1-linked processes, such as the activation of the p50 homodimeric and the p65/p50 heterodimeric isoforms of the transcription factor nuclear factor (NF)-kappaB or transcription of the acute phase reactant alpha1-acid glycoprotein (AGP), would correlate with recovery from sepsis. DESIGN: Prospective experimental comparison of sham operation and nonlethal and lethal sepsis in male Sprague-Dawley rats. INTERVENTIONS: Nonlethal sepsis was induced by using single-puncture cecal ligation and puncture (CLP). Lethal sepsis was induced via double-puncture CLP. NF-kappaB DNA binding activity was determined by using electrophoretic mobility shift analysis with differentiation of p50/p50 and p50/p65 isoforms by using appropriate antibodies. AGP transcription was assessed with transcription elongation analysis, intrahepatic IL-1beta, and TNF-alpha abundance by using immunohistochemistry, and serum IL-1beta was assessed by using ELISA. MAIN RESULTS: Overall NF-kappaB activity increased equivalently over time after both single- and double-puncture CLP, with a peak occurring 3 hrs after intervention. In single-puncture CLP, there was an increase in the binding of the p50 homodimer form over time. After double-puncture CLP, no such change was observed. AGP transcription was increased equivalently in both models. Intrahepatic IL-1beta was detected 16 and 24 hrs after single-puncture CLP and 6 hrs after double-puncture CLP. After double-puncture CLP, intrahepatic TNF-alpha was detected at 6, 16, and 24 hrs. Serum IL-1beta was undetectable after both single- and double-puncture CLP. CONCLUSIONS: Although AGP transcription was similar in mild and fulminant sepsis, double-puncture CLP increased the binding activity of the p50 homodimer relative to binding of the p50/p65 NF-kappaB heterodimer. These results imply that transcriptional activity not linked to acute phase responses is an important determinant of outcome in sepsis.

Animals↗
PubMed2001

Acute stress reactions to everyday stressful life events among sexual abuse survivors with PTSD.

This study examined symptoms of Acute Stress Disorder (ASD), which is often thought of as a precursor to PTSD, among 54 women who already had PTSD for childhood sexual abuse for which they were seeking treatment. We examined the prevalence of ASD symptoms as well as their relationships to trauma symptoms measured by the Trauma Symptom Checklist-40. The ASD diagnosis requires the occurrence of a traumatic life event as well as meeting specific symptoms criteria. We found that fourty-four percent of participants met all symptom criteria for ASD, but only three of these 24 participants described a traumatic life event. Moreover, ASD symptoms were significantly related to trauma symptom scores. These findings suggest that a significant proportion of women with PTSD for childhood sexual abuse may be highly symptomatic for everyday stressful events that would not be experienced as traumatizing to others. Thus, these individuals need assistance in coping with everyday life stressors that do not involve a serious threat or injury in addition to needing help to alleviate their trauma symptoms.

Adaptation, Psychological↗
PubMed2001

Evidence for mitogen-associated protein kinase activation and transduction of mitogenic signals by platelet-derived growth factor in human meningioma cells.

OBJECT: Coexpression of platelet-derived growth factor (PDGF)-BB and activated PDGF-beta receptor in meningioma cells indicates that this cytokine may act as an autocrine or paracrine stimulant of meningioma growth. The intracellular events transducing signals from PDGF-beta receptor tyrosine kinases are unknown. In this study the authors evaluated whether or not mitogen-activated protein kinases (MAPKs) are expressed in meningiomas, regulate their growth, and transduce mitogenic signals of PDGF-BB. METHODS: Ten human meningioma tumors as well as cells cultured from two normal leptomeninges and 10 additional human meningiomas were evaluated using Western blot analysis to determine the presence of MAPK and phosphorylated (activated) MAPK. The effects of PD098059, a selective inhibitor of MAPK phosphorylation/activation, on proliferation of meningioma cells stimulated with 10% fetal bovine serum was also evaluated. Last, the authors evaluated whether PDGF-BB stimulation of meningioma cells was associated with activation of MAPK. Western blots of lysates from meningiomas and from cultured leptomeningeal and meningioma cells demonstrated MAPK and phosphorylated MAPK. Treatment with PD098059 produced a 52 to 84% (x = 69.8) loss in [3H]thymidine incorporation, which was associated with a partial or complete loss of phosphorylated MAPK after 3 days of treatment. The PDGF-BB produced a significant increase in [3H]thymidine incorporation and phosphorylation of MAPK at 1 and 3 days. Coadministration of PD098059 completely blocked PDGF-BB's stimulation of [3H]thymidine incorporation and cell proliferation concomitant with reduced MAPK phosphorylation. CONCLUSIONS: The findings indicate that MAPK is constitutively expressed in leptomeningeal and meningioma cells and transduces mitogenic signals of PDGF, contributing to the growth of human meningiomas.

Adolescent↗