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Biomedical subjects

K Kim

Publications and source records attributed to K Kim.

At least 325 records · Page 18Linked to original sources
PubMed1997

Fast and localized event-related optical signals (EROS) in the human occipital cortex: comparisons with the visual evoked potential and fMRI.

Localized evoked activity of the human cortex produces fast changes in optical properties that can be detected noninvasively (event-related optical signal, or EROS). In the present study a fast EROS response (latency approximately 100 ms) elicited in the occipital cortex by visual stimuli showed spatial congruence with fMRI signals and temporal correspondence with VEPs, thus combining subcentimeter spatial localization with subsecond temporal resolution. fMRI signals were recorded from striate and extrastriate cortex. Both areas showed EROS peaks, but at different latencies after stimulation (100 and 200-300 ms, respectively). These results suggest that EROS manifests localized neuronal activity associated with information processing. The temporal resolution and spatial localization of this signal make it a promising tool for studying the time course of activity in localized brain areas and for bridging the gap between electrical and hemodynamic imaging methods.

Adult↗
PubMed1997

Autologous blood donation prior to anatomical radical retropubic prostatectomy: is it necessary?

OBJECTIVES: To determine if autologous blood donation prior to anatomical radical retropubic prostatectomy, given current improvements in surgical technique, is necessary. METHODS: The medical records of 200 consecutive patients undergoing radical retropubic prostatectomy for clinically localized prostate cancer were reviewed with regard to (1) preoperative hematocrit (HCT); (2) estimated blood loss (EBL); (3) postoperative HCT prior to discharge; (4) number of units of autologous blood donated; and (5) number of units of autologous and homologous blood transfused. In addition, the charges associated with autologous blood donation were determined via telephone interview with 14 blood donation centers across the United States. RESULTS: Overall, 189 patients (95%) did not require a homologous blood transfusion. Sixty-four patients (32%) donated autologous units and 136 patients (68%) did not. Of the patients who had donated, only 17 (27%) received their blood back, and none (0%) received any homologous blood. Eleven (8%) of the 136 nondonors received a blood transfusion. The autologous donors, in comparison with nondonors, were found to have a significantly lower preoperative HCT (mean +/- standard deviation: 40 +/- 4.0% versus 42 +/- 2.9%, P < 0.05). However, there was no statistically significant difference in the mean EBL between the two groups, autologous donors versus nondonors (771 +/- 370 versus 737 +/- 425 cc, P = 0.23). The autologous donors had a smaller mean change in HCT versus the nondonors (-9.3 +/- 5.1% versus -11.2 +/- 4.4%, P < 0.05), reflecting an increased willingness to transfuse patients who have autologous units available. With regard to cost, patients, on average, can expect to be charged as much as $745 per unit of autologous blood donated. CONCLUSIONS: These findings suggest that preoperative blood donation prior to radical prostatectomy may not be necessary, because 95% of the patients did not require a homologous blood transfusion. In addition, autologous blood donation can be associated with substantial costs in both time and money. Thus, autologous donation should be left as an option for the patient and should not be considered routine practice.

Adult↗
PubMed1997

Peptide-specific CTL induction in HBV-seropositive PBMC by stimulation with peptides in vitro: novel epitopes identified from chronic carriers.

Cytotoxic T lymphocytes (CTL) recognize and destroy virus-infected cells, and it has been established that epitope-based peptides could induce such CTL in vivo as well as in vitro. In this study attempts were made to define the epitopes that are recognized by the CTL, and thus a series of 9- to 10-mer peptides derived from the amino acid sequences of hepatitis B virus (HBV) proteins were synthesized on the basis of the previously described HLA-A2 peptide binding motif. The binding assay of the synthetic peptides using transporter-associated with antigen processing (TAP)-deficient human cell line, T2, showed that eight out of 11 peptides tested enhanced the expression of HLA-A2 molecules on the T2 cell surface. Some of these peptides triggered activation of CTL in peripheral blood mononuclear cells of HBV-seropositive chronic carriers. The activated CTL in turn recognized and killed the T2 cells pulsed with the same peptides. This study shows that novel HLA-A2-restricted epitopes exist in the natural repertoire of immunity against HBV. These findings can be useful in developing peptide-based therapeutics against viral infections.

Carrier State↗
PubMed1997

Induction of c-fos mRNA by lead in PC 12 cells.

Addition of lead acetate to PC 12 pheochromocytoma cells elicits induction of c-fos, an immediate early response gene. Induction of c-fos was concentration- and time-dependent: the lowest concentration of lead acetate tested that induced c-fos was 10 microM; induction was observed after a 30 min incubation and remained high after 90 min. Treatment with lead acetate and cycloheximide superinduced c-fos mRNA. Actinomycin D, an inhibitor of mRNA transcription, decreased the level of c-fos mRNA induced by lead acetate by almost 80%. Cadmium chloride and zinc chloride did not induce c-fos mRNA. Since the c-fos gene encodes a transcription factor, Pb2+ has the potential to deregulate the expression of other genes.

Animals↗
PubMed1997

Surgical management of type A aortic dissection: evaluation of predisposing factors for postoperative neurologic complication and late reoperation.

The technique of cerebral protection during hypothermic circulatory arrest remains controversial. Forty-seven patients underwent operations for type A aortic dissection in the past 9 years. During hypothermic circulatory arrest, selective cerebral perfusion and retrograde cerebral perfusion was applied in 12 and seven patients, respectively. The mortality rate was 28.6% in patients without adjunctive cerebral perfusion, 25.0% in selective cerebral perfusion patients, and zero in the retrograde cerebral perfusion group (P > 0.05). However, there was no mortality by cerebral injury in cerebral perfusion groups (P = 0.03). Age (P = 0.001), hypothermic circulatory arrest time (P = 0.012), and acuity (P = 0.013) were predisposing factors for cerebral injury, but cerebral perfusion has not yet been found to be a protective factor (P = 0.56). Nine late reoperations and three deaths occurred during the follow-up period. Marfan syndrome was the only predisposing factor for late reoperation (P = 0.016). In summary, although further studies are still required, retrograde cerebral perfusion is a possible cerebral protective factor. In addition, periodic follow-up is mandatory, especially in patients with Marfan syndrome.

Adolescent↗
PubMed1997

An automated radiopharmaceutical dispenser.

An automated radiopharmaceutical dispenser, that offers several advantages over manual procedures, has been developed. It employs a personal computer interfaced to a precision syringe drive module, a dose calibrator, and a printer. The operating program provides menu-selection operation and documentation of procedures and individual doses delivered. All materials in contact with the radiopharmaceutical are sterile and disposable. A novel transport safe is employed to further reduce radiation exposure.

Deoxyglucose↗
PubMed1997

Involvement of gamma amino butyric acid (GABA) in the postnatal function of the GnRH pulse generator as determined on the basis of GnRH and GnRH-receptor gene expression in the hypothalamus and the pituitary.

In many species the GnRH pulse generator functions early postnatally to become arrested during infancy. In rats highly variable LH levels in 15-day-old animals are suggestive that LH is being released by the pituitary in pulses whereas between day 20 after birth and puberty LH levels are low indicating that the GnRH pulse generator is arrested. In the present study we show on the basis of consecutively withdrawn blood samples in 15-day-old animals that LH pulses are indeed present at that age. The proper function of GnRH receptors in the pituitary is crucially dependent on pulsatile GnRH release from the hypothalamus. In addition, GnRH receptors have been demonstrated in the medial preoptic area and in the mediobasal hypothalamus of adult rats. In 15-day-old animals the functional GnRH pulse generator results in upregulated GnRH receptor gene expression as demonstrated by quantitative RT-PCR. It is not known what neural mechanisms are involved in turning the GnRH pulse generator off during infancy and a GABAergic brake has been discussed. Indeed, when 30-day-old animals were injected with the GABA-A receptor blocking drug bicuculline, this resulted in increased serum LH levels indicating that a tonic GABAergic inhibition is indeed operative at this age.

Aging↗
PubMed1997

In vitro metabolism of the new insecticide flupyrazofos by rat liver microsomes.

1. The in vitro metabolism of the new insecticide flupyrazofos was studied using rat liver microsomes. Two metabolites were produced and identified as O,O-diethyl O-(1-phenyl-3-trifluoromethyl-5-pyrazoyl) phosphoric acid ester (flupyrazofos oxon) and 1-phenyl-3-trifluoromethyl-5-hydroxypyrazole (PTMHP) based on UV and mass spectral analysis. 2. Cytochrome P450 oxidatively converted flupyrazofos to flupyrazofos oxon, a major metabolite and phenobarbital-induced microsomes increased this desulphuration by 8-fold. 3. Flupyrazofos oxon was converted to PTMHP with a half-life of 47.8 min by chemical hydrolysis and this conversion also proceeded non-enzymatically under our microsomal incubation conditions.

Animals↗
PubMed1997

A mutational study of the site-specific cleavage of EC83, a multicopy single-stranded DNA (msDNA): nucleotides at the msDNA stem are important for its cleavage.

Multicopy single-stranded DNA (msDNA) molecules consist of single-stranded DNA covalently linked to RNA. Such molecules are encoded by genetic elements called retrons. Unlike other retrons, retron EC83 isolated from Escherichia coli 161 produces RNA-free msDNA by site-specific cleavage of msDNA at 5'-TTGA/A-3', where the slash indicates the cleavage site. In order to investigate factors responsible for the msDNA cleavage, retron EC83 was treated with hydroxylamine and colonies were screened for cleavage-negative mutants. We isolated three mutants which were defective in msDNA cleavage and produced RNA-linked msDNA. They were all affected in msd, a gene for msDNA, with a base substitution at the bottom part of the msDNA stem. In contrast, base substitution at and around the cleavage site has no marked effect on msDNA synthesis or its cleavage. From these results, we concluded that the nucleotides at the bottom of the msDNA stem, but not the nucleotides at the cleavage site, play a major role in the recognition and cleavage of msDNA EC83.

Base Sequence↗
PubMed1997

Cisplatin, doxorubicin, and cyclophosphamide plus thoracic radiation therapy for limited-stage unresectable thymoma: an intergroup trial.

PURPOSE: To determine the response rate of cisplatin plus doxorubicin plus cyclophosphamide (PAC) in patients with limited-stage unresectable thymoma. In addition, this study was undertaken to determine the toxicity, progression-free survival, and overall survival of combined-modality therapy with PAC plus radiation therapy. PATIENTS AND METHODS: Patients with a histologic diagnosis of limited-stage unresectable thymoma or thymic carcinoma were eligible. Further requirements included a Karnofsky Performance Score of > 60, no prior radiation to the chest, and adequate bone marrow, hepatic, and renal function. No patient had undergone chemotherapy previously. Patients received two to four cycles (repeated every 3 weeks) of cisplatin (50 mg/m2), doxorubicin (50 mg/m2), and cyclophosphamide (500 mg/m2) followed by a total dosage of 54 Gy to the primary tumor and regional lymph nodes for patients with a stable, partial, or complete response to chemotherapy. RESULTS: From November 1983 through January 1995, 26 patients were entered onto the trial. Three patients were ineligible on the basis of pathologic review (lung cancer, germ cell cancer, lymphoma). Toxicity, primarily hematologic, was mild, with only one early death due to a perforated abdominal viscus. Among the 23 assessable patients, there were five complete and 11 partial responses to chemotherapy (overall response rate, 69.6%). The median time to treatment failure was 93.2 months (range, 3 to 99.2+ months), and the median survival time was 93 months (range, 1 to 110 months). The 5-year survival rate is 52.5%. CONCLUSIONS: PAC combination chemotherapy produces response rates in the management of patients with limited thymoma. Combined-modality therapy is feasible and associated with prolonged progressive-free survival. The benefit of combined-modality therapy over radiation therapy alone is suggested for patients with unresectable thymoma.

Adult↗
PubMed1997

Mitochondrial gene transfer ribonucleic acid (tRNA)Leu(UUR) 3243 and tRNA(Lys) 8344 mutations and diabetes mellitus in Korea.

The high prevalence of diabetic patients with a mutation in the mitochondrial gene (the 3243 and 8344 bp mutations) has been identified in Japan. To determine the prevalence of diabetic patients with those mutations in Korea, we randomly screened selected 503 clinical diabetic patients regardless of their diabetes types. We found only 1 patient with the mitochondrial DNA mutation at position 3243 (percent mutation, 32%), and the mitochondrial DNA mutation at position 8344 was not found in any of the patients. The affected subject was a 22-yr-old man with a history of myoclonic epilepsy and mild sensorineural hearing loss, a 1-yr duration of diabetes mellitus, and a low level C peptide response to oral glucose. Because of the low frequency of these mutations in the Korean diabetic population, we concluded that these particular mutations of mitochondrial DNA may not be a common contributor to diabetes mellitus in Korea.

Adult↗
PubMed1997

Encoding, repetition, and the mirror effect in recognition memory: symmetry in motion.

Attention/likelihood theory has been used to explain the mirror effect in recognition memory. The theory also predicts that any manipulation that affects the recognition of old items will also affect recognition of the new items-more specifically, that all the underlying distributions will move and that they will move symmetrically on the decision axis. In five experiments, we tested this prediction. The first two experiments used encoding tasks during study to change recognition performance for high- and low-frequency words. The results show symmetrical dispersion of the underlying distributions. The final three experiments used repetition to increase recognition performance. Repetition produced a symmetrical pattern of movement that was different from that produced by encoding task. This pattern is, however, also covered by attention/likelihood theory. A further extension of the theory was used to predict response times.

Adult↗
PubMed1997

Cisplatin/etoposide vs paclitaxel/cisplatin/G-CSF vs paclitaxel/cisplatin in non-small-cell lung cancer.

A phase III trial conducted by Eastern Cooperative Oncology Group (ECOG) investigators assessed the possible impact of paclitaxel on survival, response, and toxicity in patients with advanced non-small-cell lung cancer. Three regimens were compared: cisplatin/etoposide, paclitaxel/ cisplatin/granulocyte colony-stimulating factor (G-CSF), and paclitaxel/ cisplatin. Patients were randomly assigned to the regimens, each of which was repeated every 21 days over a 17-month period. Response rates were 12% in the cisplatin/etoposide group, 31% in the paclitaxel/cisplatin/G-CSF group, and 26% in the paclitaxel/cisplatin group. Significant differences in response were observed between the cisplatin/etoposide and paclitaxel/cisplatin/G-CSF groups and the cisplatin/etoposide and paclitaxel/cisplatin groups; there was no significant difference between patients treated with paclitaxel/cisplatin vs paclitaxel/cisplatin/G-CSF. Both paclitaxel regimens were associated with significantly higher response rates compared with etoposide/cisplatin. Based on preliminary survival analyses, the investigators concluded that the paclitaxel regimens may be associated with superior survival.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

Calcium supplementation.

Calcium is necessary for the prevention and treatment of diseases such as osteoporosis, hypertension, and, possibly, colon cancer. Supplementation is useful when dietary calcium intake is low, as is the current situation in North America. There are many factors to consider before recommending any one form of supplement. A consideration for calcium carbonate tablets is whether the tablet disintegrates and whether or not a lack of food or acid in the stomach will hinder utilization. Other forms of calcium, particularly the chelated calcium salts, are better absorbed in fasting achlorhydric subjects but have less calcium per gram of supplement. Interaction of calcium with other mineral nutrients and the presence of contaminating metals has focused attention on safety. Based on present evidence, chelated calcium and refined calcium carbonate tablets (including those labeled as antacids) may be safely and effectively ingested by most people at doses generally recommended for treatment or prevention of osteoporosis. One should not exceed 2,000 mg of calcium, except at the advice of their health care provider, as inadvertent mineral deficiencies may arise. Persons at risk for developing milk-alkali syndrome, such as thiazide users and persons with renal failure, should be identified and monitored for alkalosis and hypercalcemia when using calcium supplements.

Adolescent↗
PubMed1997

Lymphocyte recruitment and the kinetics of adhesion receptor expression during the pulmonary immune response to particulate antigen.

The selectins and beta2 integrins participate in the recruitment of neutrophils in acute pulmonary inflammation. However, the cell adhesion receptors that mediate lymphocyte trafficking into the lung have not been defined. This study examined the relationship between cell adhesion molecules on the pulmonary vasculature and on lymphocytes recovered from the lung during a pulmonary immune response to intratracheal (I.T.) sheep red blood cells (SRBCs) in sensitized C57BL/6J mice. Silver-enhanced immunogold staining and reverse transcriptase polymerase chain reaction of lung tissues revealed sustained induction of VCAM-1, E-selectin, and P-selectin on the pulmonary vasculature for up to 7 days after I.T.-SRBC challenge. Neither the MECA 79 nor MECA 367 antigens were induced on the pulmonary vasculature during this period. In the peripheral blood, both CD4 and CD8 T-cell subsets showed an initial increase in P-selectin ligand expression after I.T.-SRBC challenge. The number of P-selectin ligand-positive T cells in the peripheral blood fell as T cells with both P-selectin and, to a lesser extent, E-selectin ligands accumulated in the bronchoalveolar lavage fluid. We conclude that I.T.-SRBC challenge in sensitized mice elicits prolonged synthesis of P-selectin, E-selectin, and VCAM-1 by the lung vasculature as well as selectin ligand synthesis by responding T cells. Furthermore, the entry of selectin-ligand-positive T cells into the circulation and their accumulation in the bronchoalveolar lavage fluid indicates that these receptors may contribute to T cell recruitment. Finally, VCAM-1 on the vasculature may also participate; however, the vascular addressins, required for homing to peripheral and mucosal lymphoid organs, are not essential for T-cell entry into the lung following I.T.-SRBC challenge.

Animals↗