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Biomedical subjects

T Kim

Publications and source records attributed to T Kim.

At least 73 records · Page 4Linked to original sources
PubMed2000

Design and implementation of a new electrodynamic ion funnel.

A new electrodynamic (rf) ion funnel has been developed and evaluated for use in the interface regions (at approximately 1-10 Torr) of atmospheric pressure ion sources (e.g., electrospray ionization (ESI) for mass spectrometry). The ion funnel consists of a ring electrode ion guide with decreasing i.d. and with a superimposed dc potential gradient along the ring stack. The thicknesses of the ring electrodes and the spacings between them were reduced to 0.5 mm from 1.59 mm compared to those used for previous designs. The new ion funnel displays a significant improvement in low-mass transmission (m/z >200) and sensitivity compared to previous designs. The transmission efficiencies for electrosprayed peptides and proteins (ranging in mass from 200 to 17,000 Da) were typically 50-60% of total incoming currents from a heated capillary inlet. The transmitted ion currents were a factor of 30-56 greater than those of the standard interface for peptide samples and a factor of 18-22 greater than those for protein samples. The sensitivity gains realized at the MS detector were somewhat lower, possibly due to space charge effects in the octapole ion beam guide following the ion funnel. The improved ion transmission properties result primarily from the use of reduced spacings between ring electrodes. We also show that the ion funnel can be operated in two different modes, one using low-rf-amplitude scans, allowing fragile noncovalent complexes (as well as generally undesired adducts) to be transmitted, and the other using high-rf-amplitude scans, providing greater collisional activation and more effective adduct removal (or the dissociation of lower m/z species).

Electrons↗
PubMed2000

Chemotherapeutic DNA-damaging drugs activate interferon regulatory factor-7 by the mitogen-activated protein kinase kinase-4-cJun NH2-terminal kinase pathway.

Chemotherapeutic drugs and energy-rich radiation cause DNA damage, inducing signaling pathways for apoptotic cell death or cell growth arrest. The tumor suppressor gene p53 plays the critical role in the regulation of these DNA damage responses. Human tumor cells can become resistant to chemotherapy through functional inactivation of p53. Thus, it is important to identify p53-independent DNA damage signaling pathways. Here, treatment of cells with chemotherapeutic drugs or UV irradiation potentiated the transcriptional activity of IFN regulatory factor-7 (IRF7), inducing its phosphorylation and its nuclear translocation. Furthermore, IRF7 was activated by the c-Jun NH2-terminal kinase (JNK) in response to DNA-damaging agents. Activation of JNK by mitogen-activated protein kinase kinase-4 stimulated the transcriptional activity of IRF7 and induced its translocation into the nucleus. Thus, activation of IRF7 through the JNK signaling pathway may play a role in the transcriptional regulation of genes in response to DNA-damaging agents.

Antineoplastic Agents↗
PubMed2000

Expression of enhanced green fluorescent protein (EGFP) and neomycin resistant (Neo(R)) genes in porcine embryos following nuclear transfer with porcine fetal fibroblasts transfected by retrovirus vector.

In this study, we demonstrated expression of enhanced green fluorescent protein (EGFP) and neomycin resistant (Neo(R)) genes in porcine embryos following nuclear transfer from porcine fetal fibroblasts (PFFs) transduced with the EGFP and Neo(R) genes by retrovirus-mediated infection. Nuclear transfer of the nonstarved transfected PFF into enucleated oocytes was accomplished by cell to cell fusion. Out of 188 porcine eggs reconstructed by nuclear transfer, 116 (61.7%) eggs cleaved and 25 (13.3%) developed to morula and blastocyst stages. Of these 25 morulae and blastocysts, 25 (100%) embryos emitted green fluorescence. Expression of the both EGFP and Neo(R) genes was detected as early as the 2-cell stage. As determined by EGFP gene expression, mosaicism was not observed in any embryo. These results suggest that porcine oocytes reconstructed by nuclear transfer with transfected PFFs can successfully develop to the blastocyst stage. In addition, this approach might be applicable to the production of transgenic pigs with complex genetic modifications.

Animals↗
PubMed2000

T2-weighted MR imaging for focal hepatic lesion detection: supplementary value of breath-hold imaging with half-Fourier single-shot fast spin-echo and multishot spin-echo echoplanar sequences.

The purpose of our study was to evaluate the supplementary value of breath-hold fat-suppressed T2-weighted magnetic resonance (MR) imaging with half-Fourier single-shot fast spin-echo (SE) or multishot SE echoplanar (EP) sequences combined with respiratory-triggered fat-suppressed fast SE T2-weighted MR imaging for detection and characterization of focal hepatic lesions. MR images in 42 patients with 82 solid, malignant and 77 nonsolid, benign lesions were analyzed. Image review was conducted on a segment-by-segment basis; in all, 333 liver segments were reviewed separately for solid and nonsolid lesions by three independent radiologists. For solid lesions, observer performance with receiver-operating-characteristic (ROC) analysis in one radiologist and specificity in another significantly improved after adding single-shot fast SE images. For nonsolid lesions, observer performance with ROC analysis in one radiologist and specificity in another significantly improved after adding single-shot fast SE images. Combining breath-hold half-Fourier single-shot fast SE imaging with respiratory-triggered fast SE imaging may be recommended for improved detection and characterization of focal hepatic lesions. J. Magn. Reson. Imaging 2000;12:444-452.

Adipose Tissue↗
PubMed2000

The effects of age and previous experience on social rank in female red junglefowl, Gallus gallus spadiceus.

Social rank can influence lifetime reproductive success and therefore fitness. We examined the effects of morphology, age, previous social experience and aggressiveness on social rank in all-female flocks of red junglefowl. None of the morphological characters measured (mass, tarsus length, comb height or comb length) appeared to play a role in determining rank. Older females were not more likely to be dominant, while previous social experience and aggression levels were both important in dominance determination. Flock-experienced hens were more likely to be dominant as were more aggressive individuals. Red junglefowl females most likely use a combination of characters to establish social order in a newly formed flock. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2000

Synthesis and biological activity of conformationally controlled 2-PAM derivatives.

A series of conformationally controlled 2-PAM derivatives were prepared from 2-acetylpyridine and 2,3-pyrido[b]cycloalkenones in two steps and their reactivities towards parathion poisoned AChE were evaluated. The most planar 2,3-pyrido[b]cyclohexanone oxime methiodide showed an activity comparable to 2-PAM implying E-syn is that the most active conformation of 2-PAM in the biological system.

Acetylcholinesterase↗
PubMed2000

Clinical features of sudden hearing loss associated with a high signal in the labyrinth on unenhanced T1-weighted magnetic resonance imaging.

We report on five patients with high signals in the labyrinth on unenhanced magnetic resonance imaging who developed sudden hearing loss and vertigo. Weissman et al. (1992) suggested the possibility that such high signals were caused by hemorrhage. We assessed these patients using audiograms, caloric tests, and auditory brainstem responses to investigate the possibility of inner ear hemorrhage. Most of the patients were found to have severe and irreversible impairment of both cochlear and vestibular function. These findings were consistent with the hypothesis that their symptoms were caused by inner ear hemorrhage.

Adolescent↗
PubMed2000

Blepharoptosis-induced superior keratoconus.

PURPOSE: This clinical case report demonstrates blepharoptosis-induced corneal steepening and its subsequent resolution after blepharoptosis surgery. METHODS: A 62-year-old man complaining of blurred vision without apparent cause on clinical examination underwent keratometry and computerized corneal topography, which revealed superior corneal steepening in both eyes. Bilateral upper eyelid blepharoptosis surgery was performed. RESULTS: Three months after blepharoptosis surgery, repeat computerized corneal topography revealed normal corneal contours with improved vision in both eyes. CONCLUSIONS: Blepharoptosis is a common condition that may induce superior corneal ectasia that is not evident by manifest refraction, slit-lamp examination, or keratometry. Computerized corneal topography can help detect such subtle corneal abnormalities and guide therapy.

Blepharoplasty↗
PubMed2000

Effects of mobile buffers on facilitation: experimental and computational studies.

Facilitation is an important form of short-term plasticity that occurs in most synapses. At crayfish neuromuscular junctions, basal transmission and facilitation were significantly reduced after presynaptic introduction of "fast" high-affinity calcium buffers, and the decay of facilitation was accelerated. The existence of residual calcium during facilitation was also demonstrated. Computational modeling of three-dimensional buffered Ca(2+) diffusion and binding to secretory and facilitation targets suggest that the facilitation site is located away from a secretory trigger mediating exocytosis; otherwise, the facilitation site would be saturated by each action potential. Our simulations account for many characteristics of facilitation and effects of exogenous buffer, and suggest that facilitation is caused by residual calcium gaining access to a site distinct from the secretory trigger through restricted diffusion.

Animals↗
PubMed2000

Indications for and outcomes of repeat penetrating keratoplasty, 1989-1995.

OBJECTIVE: To evaluate the indications for and outcomes of repeat penetrating keratoplasty over a 7-year period and compare them to a similar study over the prior 6-year period at the same institution. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Two hundred twenty-three consecutive repeat corneal transplants performed by one of five corneal surgeons between 1989 and 1995 were studied. MAIN OUTCOME MEASURES: Reasons for primary and regraft failure, indications for the initial corneal graft, graft clarity, and best-corrected visual acuity were measured on each patient. RESULTS: Between 1989 and 1995, 16% (271 of 1689) of transplants performed by our cornea group were regrafts compared with 9% (165 of 1860) in the period from 1983 to 1988 (P < 0.01). The most common indications for penetrating keratoplasty before regraft were pseudophakic bullous keratopathy (27%, 61 of 223), failed graft (20%, 44 of 223), Fuchs' dystrophy (11%, 24 of 223), aphakic bullous keratopathy (9%, 21 of 223), keratoconus (8%, 17 of 223), and herpes simplex keratitis (6%, 14 of 223). Compared with the prior study period of 1983 to 1988, an increase was revealed in the incidence of failed graft (11% to 20%, P = 0.03), and a decrease was revealed in the incidence of aphakic bullous keratopathy (19% to 9%, P = 0.01). Of the 223 regrafts, 55 (25%) failed during the study period (range, 1 month to 7.5 years; mean 2.1 years). Eleven percent (6 of 55) of regraft failures occurred within 6 months, and 55% (30 of 55) failed within 18 months. Of the 150 regrafts with 2 years follow-up (mean, 3.9 years), 111 (74%) had clear grafts. A best-corrected visual acuity of 20/20 to 20/40 was achieved in 41% (46 of 111), 20/50 to 20/100 in 32% (36 of 111), 20/200 to 20/400 in 21% (23 of 111), and counting fingers to no light perception in 5% (6 of 111). CONCLUSIONS: Failed grafts are increasing as an indication for penetrating keratoplasty. Graft clarity and visual acuity results continue to be very good, supporting the use of repeat corneal transplantation.

Aged↗
PubMed2000

Ultrasonographic measurement of induced myopia associated with capsular bag distention syndrome.

OBJECTIVE: To determine the causes of postoperative myopia associated with capsular bag distention syndrome (CBDS) and characterize the associated findings. DESIGN: Prospective, multicenter, nonrandomized, comparative (self-controlled) trial. PARTICIPANTS: Six eyes from six patients had CBDS develop after phacoemulsification and posterior chamber intraocular lens implantation. METHODS: Keratometric values, axial length, visual acuity, and manifest refraction were assessed in each eye. Using 20-MHz (I3SYSTEM-ABD, Innovative Imaging Inc, Sacramento, CA) and 50-MHz (Ultrasound Biomicroscope, Zeiss Humphrey Systems, Dublin, CA) ultrasonographic probes, images and measurements of the anterior segment were obtained. After neodymium:yttrium-aluminum-garnet (Nd:YAG) capsulotomy, these measures were repeated and correlated with predicted and actual refractive changes. MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction, and anterior chamber depth before and after treatment of CBDS. RESULTS: Although intended postoperative refraction averaged -0.58 diopters (D) (range, -0.12 to -1.63 D), eyes with CBDS had an average spherical equivalent refraction of -2.35 D (range, +0.13 to -4.50 D), P < 0.05 (one-tailed, paired t test). BCVA averaged 20/24 (range, 20/15-20/40-1), but UCVA averaged 20/133 (range, 20/60 to 20/400). Average distance from the corneal surface to the anterior intraocular lens (IOL) optic surface was 3.55 mm in eyes with CBDS, and 4.30 mm after Nd:YAG capsulotomy. Posterior movement of the IOL optic after capsulotomy accounted for 1.23 D of hyperopic shift or 82% of the CBDS-induced myopia. Treatment of CBDS resulted in both improved UCVA and BCVA. Nd:YAG capsulotomy also released the colloidal suspension within the capsular bag posterior to the IOL optic. The incidence of CBDS was 0.3% in one of the practices reviewed. CONCLUSIONS: Capsular bag distention syndrome includes unexpected myopia and poor UCVA after cataract surgery with lens implantation in cases involving a continuous capsulorhexis. A dramatic posterior distention of the posterior capsule is observed, as well as anterior chamber shallowing, tight apposition of the iris to the IOL, and anterior bowing of the iris. A slightly turbid colloidal suspension behind the IOL implant and late posterior capsular fibrosis are also observed. Timely treatment of CBDS can correct unwanted myopia, improve UCVA and BCVA, and restore normal anatomic relationships in the eye.

Aged↗
PubMed2000

The natural history and prognostic factors in patients with cirrhosis and gastric fundal varices without prior bleeding.

Objectives and methods: The prognostic factors have not yet been fully evaluated in patients with cirrhosis and gastric fundal varices (FV). We investigated the natural history of 145 patients with cirrhosis and FV with no history of bleeding. Various possible prognostic factors, which include clinical, biochemical, and endoscopical variables, were analyzed using Cox's proportional hazard model. Results: Among the 145 patients with cirrhosis and FV, there were 76 patients in class A, 45 in class B and 24 class C according to Child's classification. Sixty-five patients had concomitant hepatocellular carcinoma at the time of enrollment. Seventy deaths and 34 episodes of the hemorrhage from FV occurred during the mean follow-up period of 26.4 months. The cumulative survival rates at 1, 3, and 5 years were 75, 53 and 34%, respectively. The cause of death was related to gastrointestinal hemorrhage in 18 patients (15 deaths were related to FV hemorrhage), hepatic failure in 22, hepatocellular carcinoma in 22, and other causes in eight patients. In patients with small-, medium-, and large-sized FV, the deaths related to FV hemorrhage were 4, 21 and 54%, respectively. Overall, the death related to FV hemorrhage was 21%. A multiple regression analysis using Cox's model showed hemorrhage from FV, the presence of hepatocellular carcinoma and poor Child's status were all highly significant prognostic factors. Conclusion: The natural history of the patients with cirrhosis and FV was adversely modified by the hemorrhage from FV, concomitant hepatocellular carcinoma and poor hepatic functional reserve. Since the number of deaths related to FV hemorrhage was great in patients with large-sized FV, it is important to identify high-risk large FV and its prophylactic obliteration. Further studies are needed to elucidate the efficacy of prophylactic obliteration of large-sized FV.

Journal Article↗
PubMed2000

Effects of mixing on fed-batch fermentation of L-ornithine.

The effects of mixing on L-ornithine fermentation were studied using an L-arginine auxotrophic mutant of Brevibacterium ketoglutamicum ATCC 21092. Three different modes of fed-batch culture using two different impeller types were studied in a 7 l fermentor. The first two modes of fed-batch culture were carried out in a fermentor equipped with six-flat-blade disk-turbine impellers with top and bottom feeding. The third mode of fed batch culture was carried out using pitched-six-flat-blade disk-turbine impellers with top feeding. The titre of L-ornithine increased up to 1.8 fold with bottom-feeding or when the pitched-six-flat-blade disk-turbine impellers were used compared to when the six-flat-blade disk-turbine impellers with top-feeding were used. It was observed that the mixing time of the limiting nutrients varied significantly depending on both the direction of feeding and the impeller type. Since the profiles of the specific rates of CO2 evolution, oxygen and glucose uptakes were very similar for the three culture modes, it could be reasonably assumed that the microorganism exhibited similar growth rates for each mode used. However, different amino acid producing activities were observed in the three culture modes. From these results it is concluded that the productivity of L-ornithine fermentation is significantly improved by shortening the mixing time of the limiting nutrient in the fermentor.

Journal Article↗
PubMed2000

Multishot echo-planar imaging with gadopentetate dimeglumine. Preliminary study of efficacy for detection of hypovascular metastatic liver tumors.

OBJECTIVE: To evaluate the usefulness of sequential T2-weighted spin-echo type multishot echo-planar (T2-EP) imaging with gadopentetate dimeglumine for the detection of hypovascular metastatic liver tumors. MATERIAL AND METHODS: Fifteen consecutive patients with 56 proven hypovascular metastatic liver tumors were included in the study. Three observers blindly and independently read the whole-liver images obtained with T2-weighted spin-echo, T2-weighted single-shot fast spin-echo, T1-weighted fast multiplanar spoiled GRASS and T2-EP images obtained before and 25, 60, 90 and 120 s after injection of 0.2 mmol/kg b.w. of gadopentetate dimeglumine. The diagnostic accuracy was estimated by calculating the area under the observer-specific binomial receiver operating characteristics curves (Az). RESULTS: T2-EP images obtained 60 s after contrast injection showed significantly higher contrast-to-noise (C/N) ratios than the other imaging techniques. A combination of all phases of the T2-EP images produced the highest sensitivity and specificity. In terms of the Az value, the diagnostic accuracy for tumor detection achieved with a combination of all phases of the T2-EP images was significantly higher than that with T1-SPGR and T2-SSFSE images (p<0.01). The Az values of the T2-EP images (Az=0.975) were higher than those of T2-CSE images (Az=0.948), but the difference was not significant. CONCLUSION: Our preliminary study revealed that sequential imaging with enhanced T2-EP images was useful for the detection of hypovascular metastatic liver tumors because of its superior C/N ratio and sensitivity.

Adult↗
PubMed2000

Modified extravesical ureterocystoneostomy of the kidney transplant allograft with completely duplicated ureters.

BACKGROUND: The technique of ureterocystoneostomy for completely duplicated ureters has not yet been established. We report on a case of a living-related transplant recipient who successfully received his mother's kidney having completely duplicated ureters. METHODS/RESULTS: The recipient was a 33-year-old male patient introduced to hemodialysis due to focal glomerulosclerosis. The donor was his 60-year-old mother having left completely duplicated ureters. We adopted the modified extravesical ureterocystoneostomy technique. Postoperative drip infusion pyelography and voiding cystography of the recipient showed no evidence of urinary tract obstruction or vesicoureteral reflux. CONCLUSIONS: We conclude that this technique is suitable for the transplantation of the kidney with complete ureteral duplication.

Adult↗
PubMed2000

Quantification of rebound edema after steroid treatment.

OBJECTIVE: Return of edema after abrupt discontinuation of steroid treatment has never been studied or quantified. The purpose of this study was to measure the effect of abrupt cessation and tapering doses of steroids on tissue water content (TWC) in a rat skin flap model. DESIGN: A randomized controlled animal trial was designed to study the effects of discontinuation of steroid on skin flap edema. The animals were assigned to a control group (C), a steroid group (S), an abrupt steroid cessation (SC) group, or a tapering steroid (ST) group. MAIN OUTCOME MEASURES: In each group the skin flaps were biopsied at 30 and 36 hours. TWC was determined by a biopsy-drying technique. RESULTS: A significant difference (P = 0.05) was found between the C and S groups and between the SC and S groups at both 30 and 36 hours, with the C group having the highest TWC. No significant difference was noted between the SC and C groups. The ST group had significantly less edema than the C group and similar TWC to that of the S group. CONCLUSION: Edema rebounded in the skin flaps after abrupt cessation of steroids (SC was not different from C), presumably because of destabilization of inflammatory mediators. The rebound effect was not observed in the ST group. The control of rebound edema by a tapering steroid protocol may be important in skin flap survival and may have implications for the management of airway edema.

Animals↗
PubMed2000

Clinical implications of detection of Ureaplasma urealyticum in the amniotic cavity with the polymerase chain reaction.

OBJECTIVE: The objective of this study was to determine the frequency and clinical significance of the detection of Ureaplasma urealyticum by means of the polymerase chain reaction with specific primers in the amniotic fluid of patients with preterm premature rupture of membranes. STUDY DESIGN: Amniocentesis was performed in 154 patients with preterm premature rupture of membranes. Amniotic fluid was cultured for aerobic and anaerobic bacteria and for mycoplasmas. Ureaplasma urealyticum was detected by means of the polymerase chain reaction with specific primers. Patients were divided into the following 3 groups according to the results of amniotic fluid culture and polymerase chain reaction for U. urealyticum: those with a negative amniotic fluid culture and a negative polymerase chain reaction (n = 99), those with a negative amniotic fluid culture but a positive polymerase chain reaction (n = 18), and those with a positive amniotic fluid culture regardless of the results of the polymerase chain reaction (n = 37). Contingency table and survival techniques were used for analysis. RESULTS: (1) U. urealyticum was detected by polymerase chain reaction in 28% (43/154) of patients and by culture in 16% (25/154). (2) Among the 43 patients with a positive polymerase chain reaction for U urealyticum, amniotic fluid culture was negative in 42% (18/43). (3) Patients with a negative amniotic fluid culture for U urealyticum but a positive polymerase chain reaction had a significantly shorter median interval from amniocentesis to delivery and a higher amniotic fluid interleukin 6 and white blood cell count than did those with a negative amniotic fluid culture and a negative polymerase chain reaction (interval to delivery; median, 53 hours; range, 0.3-335 hours; vs. median, 141 hours; range, 0.1-3552 hours; P<.05; amniotic fluid white blood cell count: median, 513 cells/mm(3); range, 1-2295 cells/mm(3); vs. median, 1 cell/mm(3); range, 0-7956 cells/mm(3); amniotic fluid interleukin 6: median, 16.6 ng/mL; range, 0.3-53.0 ng/mL; vs. median 0.4 ng/mL; range, 0-69.8 ng/mL; P<.0001 for all). (4) Patients with a positive polymerase chain reaction for U. urealyticum but a negative amniotic fluid culture had a higher rate of significant neonatal morbidity than did those with both a negative culture and a negative polymerase chain reaction (P<.05). (5) No significant differences in perinatal outcome were observed between patients with a negative culture but a positive polymerase chain reaction and those with a positive amniotic fluid culture. CONCLUSION: (1) Culture techniques for mycoplasmas missed 40% of cases of microbial invasion of the amniotic cavity with U. urealyticum. (2) Patients with a positive polymerase chain reaction but a negative amniotic fluid culture are at risk for adverse outcomes. (3) The use of molecular microbiologic techniques is likely to increase the detection of infection among patients with obstetric complications.

Adult↗