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Biomedical subjects

J H Kim

Publications and source records attributed to J H Kim.

At least 19 recordsLinked to original sources
PubMed1992

Effect of pH on quercetin-induced suppression of heat shock gene expression and thermotolerance development in HT-29 cells.

When cells were heated for 15 min at 45 degrees C, they became thermotolerant to a second heat exposure at 45 degrees C. Thermotolerance developed rapidly, reached its maximum 6 hr after heat shock, and then gradually decayed. The development of thermotolerance was partially suppressed by treatment with various concentrations of quercetin (0.05-0.2 mM) at pH 7.4 after the initial heat treatment. In contrast, the drug markedly inhibited thermotolerance development at pH 6.5. Furthermore, a combination of low pH and quercetin treatment distinctively altered the expression of HSP70 gene compared with that of HSP28 or HSP90 gene. These results demonstrate a good correlation between the amount of HSP70 gene expression and development of thermotolerance.

Blotting, Northern↗
PubMed1992

Quantitative magnetic resonance imaging in temporal lobe epilepsy: relationship to neuropathology and neuropsychological function.

Magnetic resonance images (MRIs) were obtained from 25 patients with medically refractory epilepsy of temporal lobe origin (12 on the left, 13 on the right) and 14 right-handed control subjects. The hippocampi and temporal lobes were traced by computer on successive coronal images and the resulting measurements of area were summed for each region. The left and right hippocampi were symmetrical in the control subjects; however, for patients the hippocampus was smaller on the side of the seizure focus. Moreover, the left-right hippocampal ratio significantly differentiated the control subjects from each patient group. The left temporal lobe was significantly smaller than the right in control subjects. The epileptics' temporal lobes were smaller on the side of the seizure focus, compared to the temporal lobes in the control subjects. MRI hippocampal measurements were compared to hippocampal neuronal densities obtained postoperatively. Significant correlations were obtained between the ratio (side ipsilateral to focus/side contralateral to focus) of MRI hippocampal measurements and neuronal densities in all hippocampal subfields except CA2. Prior to surgery, patients were administered the Wechsler Memory Scale and the verbal Selective Reminding Test. Significant correlations existed between MRI measurements of the left hippocampus and the Wechsler logical memory percent retention scores and between the left temporal lobe measurements and the verbal Selective Reminding Test scores for patients with seizure foci in the left temporal lobe.

Adolescent↗
PubMed1992

Structural investigation of helices II, III, and IV of B. megaterium 5S ribosomal RNA by molecular dynamics calculations.

The structures of the helices II-III region and the helix IV region of B. megaterium 5S rRNA have been examined by means of energy minimization and molecular dynamics calculations. Calculated distances between neighboring hydrogen-bonded imino protons in helices II, III, and IV were between 3.5 and 4.5 A. The overall axis for the helices II-III region is warped rather than straight. Formation of additional Watson-Crick base pairs in loop B and loop C was not evident from the atomic positions calculated by molecular dynamics. Bases in loop C are well stacked, showing no significant change during dynamics. Bulge migration in helix III does not seem to be possible; the helices II-III region prefers one conformation. Helix II is more stable than helix III. Five base pairs in helix IV were sufficiently stable to establish that helix IV is terminated by a hairpin loop of three nucleotides. U87 protrudes from loop D. Structures of the helices II-III segment and the helix IV segment of B. megaterium 5S rRNA obtained by molecular dynamics were generally consistent with the solution structure inferred from high-field proton nmr spectroscopy.

Bacillus megaterium↗
PubMed1992

Use of antisense RNA to confer bacteriophage resistance in dairy starter cultures.

The strategy and implementation of a unique system for engineering bacteriophage resistant starter cultures of Lactococcus lactis employing antisense RNA is reviewed. As a necessary prerequisite for developing this system, we have cloned and sequenced a number of bacteriophage genes coding for minor and major structural proteins. In addition, we have also identified a series of genes whose function(s) is not known but their sequences appear to be conserved in a vast number of isolates. One of these latter sequences, designated gp51C, codes for a 51-kDa protein which is extremely charged and shares some homology with yeast translation initiation factor. Resistance to a broad class of isometric bacteriophages has been achieved by expression of an antisense RNA targeted against, for example, gp51C. In the best case, expression of the antisense gp51C RNA results is a greater than 99% reduction in the total number of plaque forming units. Additional antisense RNA constructs directed against other bacteriophage genes, including the major capsid protein, also appear effective at inhibiting infection from 40-55% suggesting that this approach may prove useful for engineering a set of truly isogenic strains to be used in a starter culture rotation plan.

Bacteriophages↗
PubMed1992

Comparison of 180-degree and 360-degree skeletal muscle nerve cuff electrodes.

Use of skeletal muscle for cardiac augmentation is a promising technique for treatment of end-stage cardiac failure. An electrode woven through the latissimus dorsi that recruits nearby nerve fibers is commonly used to pace skeletal muscles both in clinical practice and in the laboratory. A proximally placed nerve cuff electrode offers potential advantages in improved recruitment of muscle fibers and low threshold for stimulation. We tested the effectiveness of a nerve cuff electrode passed directly about the proximal thoracodorsal nerve. Our report looks at the efficacy of nerve cuff electrode stimulation and compares electrical and histologic characteristics of a 180-degree wrap of the thoracodorsal nerve to a 360-degree wrap in dogs over 3 months. Threshold voltage at the commonly used pulse width of 200 microseconds was typically in the range of 400 to 600 mV for each electrode after 3 months. Statistical analysis revealed no significant difference (p < 0.05) in threshold voltage or current between the 180-degree and 360-degree nerve cuff electrode either at acute evaluation or after 3 months. Even contraction of latissimus dorsi was achieved with all implants. Adenosine triphosphatase staining revealed 100% conversion of type II to type I fibers in all stimulated muscles. Histologic examination of the thoracodorsal nerve and latissimus dorsi muscle revealed no abnormalities grossly or by light microscopy. Thus, a carefully applied nerve cuff electrode is an atraumatic, effective method for skeletal muscle stimulation. The 180-degree and 360-degree nerve cuff configurations are equally effective.

Adenosine Triphosphatases↗
PubMed1992

Increases in tumor response by pentoxifylline alone or in combination with nicotinamide.

Pentoxifylline (PENTO), a derivative of methylxanthine, has been reported to improve fluidity of red blood cells (RBC), and thus improve the flux of RBC through narrow capillaries. Additionally, PENTO increases 2,3-DPG levels in RBC, thereby increasing the O2 release from RBC. Nicotinamide (NA) has been known to increase tumor blood flow, reducing the hypoxic cell fractions in the tumors. The purpose of this study was to examine the effects of PENTO alone or in combination with NA (PENTO + NA) on the oxygenation and radio-response of FSaII murine fibrosarcomas of mice. We observed a significantly enhanced, radiation-induced growth delay of the FSaII tumors by the treatment of either single or multiple injections of PENTO. The combination of PENTO and NA further delayed the growth of tumors. The TCD50 of control tumors was about 56.6 Gy, whereas that of PENTO + NA treated tumors was about 31.9 Gy. Thus, TCD50 was modified by a factor of 1.8. PENTO + NA exerted no effect on the acute skin damage of C3H mice after local irradiation and the gastrointestinal death after whole body irradiation. However, PENTO + NA slightly increased the bone marrow death as demonstrated by the decrease in LD50(30) from 5.5 Gy to 5.2 Gy. The average pO2 in the saline-treated control group of FSaII tumors was 8 mmHg and it significantly increased to 19 mmHg in the PENTO + NA treated group (p less than 0.001). We concluded that the PENTO + NA treatment increased the radio-response of tumors by improving tumor oxygenation.

Animals↗
PubMed1992

Potentiation of radiation response in human carcinoma cells in vitro and murine fibrosarcoma in vivo by topotecan, an inhibitor of DNA topoisomerase I.

DNA topoisomerase I, a nuclear enzyme important for solving topologic problems arising during DNA replication, has been identified as a principal target of a plant alkaloid, 20(s)-camptothecin. In view of the profound biochemical effects of camptothecin and its analogues on DNA replication and the differential cytotoxic effects on human tumors in xenografts, experiments were performed to determine whether topotecan, a camptothecin analogue, would potentiate the radiation effects on human carcinoma cells in culture and murine fibrosarcoma in mice. Cell culture studies showed that a dose dependent reduction in cell survival was obtained with a 4 hr exposure of the drug following irradiation of cells. No enhancement of cell killing was seen when cells were treated with the drug before irradiation. Preliminary in vivo tumor studies showed a significant radiosensitizing effect of topotecan that was both drug dose (20 mg/kg) and time sequence (4 hr before irradiation) dependent. There was no enhanced skin reaction following the combined treatments.

Animals↗
PubMed1992

Effect of neodymium:YAG laser photodisruption on intraocular lenses in vitro.

Poly(methyl methacrylate) (PMMA) based intraocular lenses (IOLs) such as injection-molded PMMA and lathe-cut PMMA IOLs and soft IOLs such as silicone and poly(hydroxyethyl methacrylate)(polyHEMA) IOLs were tested for vulnerability to Nd:YAG laser photodisruption. The laser beam was focused on the posterior surface and inside of the IOLs in balanced salt solution. Cracks and central defects with radiating fractures were observed in PMMA IOLs; blistered lesions and localized pits were observed in silicone and polyHEMA IOLs, respectively. A molten edge surrounding the large hole, which was an indication of the thermal effect of the laser, was observed in the injection-molded PMMA while only a minute lesion was found in the polyHEMA IOL which contained 38% water. The size of the superficial damage of the IOL increased as the power of laser irradiation increased and PMMA IOLs showed greater damage than soft IOLs (P < .05).

Lasers↗
PubMed1992

Endoscopic application of Gianturco-Rösch biliary Z-stent.

Ginaturco-Rösch Z-stent is a new self-expanding stainless steel stent for drainage of the obstructed biliary system. It has been used only with a percutaneous transhepatic technique. We describe a new method for endoscopic retrograde placement of a Gianturco-Rösch biliary Z-stent. This report describes our experience for endoscopic application of a Gianturco-Rösch biliary Z-stent in a patient with a benign stricture and multiple common bile duct stones.

Aged↗
PubMed1992

Specificity in the correlation of verbal memory and hippocampal neuron loss: dissociation of memory, language, and verbal intellectual ability.

Fifty-nine patients with temporal-lobe epilepsy (28 left, 31 right) completed the Boston Naming Test (BNT), verbal subtests of the Wechsler Adult Intelligence Scale-Revised, and the Logical Memory Subtest of the Wechsler Memory Scale (WMS) before surgery. Performances by patients with left temporal seizure foci were significantly more impaired than those of patients with right seizure foci on the WMS Logical Memory subtest and the BNT. After surgical removal of the mesial temporal lobe structures, two blinded observers established volumetric cell densities for hippocampal subfields CA1, CA2, CA3, the hilar area, and the granule cell layer of area dentata. Statistically significant correlations existed only between percent retention scores and hippocampal neuron loss in CA3 and the hilar area for patients with left temporal seizure foci. None of the other dependent measures was significantly correlated with hippocampal neuron density in any subfield. These results support the hypothesis that certain verbal memory impairments are attributable to hippocampal damage specifically, and not to temporal lobe damage in general.

Adult↗
PubMed1992

Fungal scleritis after cataract surgery. Successful outcome using itraconazole.

We report the development of fungal scleritis in a 53-year-old man after uncomplicated cataract surgery. Histopathology and culture identified the organism as Aspergillus flavus. Clinically, the patient worsened on treatment with oral ketoconazole and topical amphotericin B with progression of multifocal scleral nodules and necrosis. Resolution of inflammation was achieved using oral itraconazole, a new triazole antifungal agent. The patient achieved 20/15-2 visual acuity and remains free of symptoms and signs for greater than 2 years after discontinuation of all treatment.

Administration, Oral↗
PubMed1992

Characterization of the cytokeratins of human colonic, pancreatic, and gastric adenocarcinoma cell lines.

Cytokeratin-type intermediate filaments are a polygenic family of insoluble proteins that vary according to cell of origin and have been proposed as potentially useful markers of differentiation in epithelial malignancies. Because gastrointestinal malignancies resemble each other in their expression of many soluble antigens, we compared the cytokeratins of seven colonic, three gastric, six pancreatic, and one duodenal carcinoma cell lines, and one colon villous adenoma cell line. Cytokeratins were characterized by one- and two-dimensional gel electrophoresis, immunoblotting, and immunocytochemistry. These cell lines expressed combinations of cytokeratins 7, 8, 18, and 19, which are typical of the "simple" epithelial pattern found in normal ductal and glandular tissues of the gastrointestinal tract. However, pancreatic carcinoma cell lines expressed additional cytokeratins that are normally found in stratified squamous epithelium and epidermoid (squamous cell) carcinomas. These additional cytokeratins consisted of cytokeratin 16 in all six cell lines and cytokeratins 4, 13, and 16 in one cell line. These results suggest that cytokeratin patterns represent stable markers that may aid in distinguishing gastrointestinal malignancies.

Adenocarcinoma↗
PubMed1992

The inhibitory effects of müllerian-inhibiting substance on epidermal growth factor induced proliferation and progesterone production of human granulosa-luteal cells.

This study was undertaken to determine if Müllerian-inhibiting substance (MIS) could block basal and/or epidermal growth factor (EGF)-induced proliferation and progesterone production by cultured human granulosa-luteal cells. Cells from follicles of individual patients were pooled, counted, and aliquoted into Ham's F-10 medium containing 10% MIS-free female fetal calf serum at 37 C in 95% air and 5% CO2. After assessing viability, cells were counted on days 4, 8, 12, and 16 of culture. EGF was added every other day at 0.2, 2, and 20 ng/mL beginning on culture day 4. The greatest stimulatory effect of EGF on cell proliferation was observed at 20 ng/mL on days 12 and 16. EGF increased progesterone production per cell after 4 days exposure, but this effect was lost after 8 days. Granulosa-luteal cells were cultured with 0.2, 2, and 20 ng/mL immunoaffinity purified recombinant human MIS (rhMIS) or conditioned medium from Chinese hamster ovary cells transfected with the human MIS gene, beginning on culture day 4. rhMIS demonstrated its greatest inhibitory effect on cell proliferation at 20 ng/mL on day 16. The rhMIS decreased progesterone production per cell after 4 days exposure, but only in the higher doses. Maintaining EGF at 20 ng/mL and varying rhMIS yielded significant reduction in EGF-mediated proliferation and progesterone production per cell at 2 and 20 ng/mL rhMIS. These experiments demonstrate rhMIS inhibits basal and EGF-stimulated human granulosa-luteal cell proliferation and progesterone production.

Adult↗
PubMed1992

"Central" and "peripheral" benzodiazepine receptors: opposite changes in human epileptogenic tissue.

We measured the density of two benzodiazepine (BZ) receptor subtypes in neurosurgically obtained hippocampal tissue from the seizure focus of patients with temporal lobe epilepsy (TLE) showing mesial temporal sclerosis, the most common pathologic finding in TLE. We performed quantitative in vitro receptor autoradiography with [125I]Ro 16-0154, a probe for the central-type BZ receptor and with [3H]PK 11195, a probe for the peripheral-type BZ receptor. In comparison with autopsy and neurosurgical control groups, patients with mesial temporal sclerosis had regionally selective decreased central-type and increased peripheral-type BZ receptors. These changes paralleled regional losses of neurons and proliferation of glia. Decreases of the inhibitory central-type BZ receptor may be a component of the enhanced excitability of the seizure focus and also may allow localization of the focus by in vivo neuroreceptor imaging. Single photon emission computed tomography (SPECT) imaging of two TLE patients with [123I]Ro 16-0154 suggests that this technique may provide a more sensitive means of localizing the seizure focus than current imaging methods relying on changes in blood flow or glucose metabolism.

Adult↗