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Biomedical subjects

I Y Kim

Publications and source records attributed to I Y Kim.

At least 19 recordsLinked to original sources
PubMed2006

Regulation of adipocyte differentiation by PEGylated all-trans retinoic acid: reduced cytotoxicity and attenuated lipid accumulation.

Obesity is major risk factor for many disorders, including diabetes, hypertension and heart disease. Unfortunately, there is a dearth of therapeutic agents available to clinicians for the treatment of obesity. The principal aim of this study was to investigate whether PEGylated all-trans retinoic acid (PRA) can have favorable stability and biological activity in 3T3-L1 preadipocytes as an antiobesity drug. Here, we found that PRA inhibits the process of adipogenesis, including survival of adipocytes and differentiation to mature adipocytes. The results showed that RA nanoparticles (NPs) were prepared by PEGylation; below 200 nm, PRA-NPs were obtained. Moreover, PRA decreased glycerol-3-phosphate dehydrogenase activity in 3T3-L1 preadipocytes by acting with major adipocyte marker proteins such as PPARgamma2, C/EBPalpha and aP2 modulators. Apoptosis, in addition, increased as the level of RA increased from 10 to 20 microM, whereas PRA reduced apoptosis with increasing concentrations. Our data suggest that PRA-NP has potential as an antiobesity drug carrier due to its small particle size and PEGylated core-shell structure. In addition, our results suggest that PRA inhibits the process of adipogenesis and may be developed to treat obesity. Based on these results, PRA is suitable for adipocyte studies, and an enhanced effect of PRA with adipocyte differentiation offers a challenging approach for pharmaceutical applications.

3T3 Cells↗
PubMed2005

Small cell carcinoma of the colon: barium study and CT findings.

Extrapulmonary small cell carcinoma is a rare neoplasm. It is an aggressive malignant tumour characterized by rapid local progression and early metastasis. We report a case of small cell carcinoma arising in the transverse colon in a 34-year-old man who presented with epigastric pain. On CT, a poorly enhancing bulky mass encircling the transverse colon with extensive regional lymph node metastases was observed. A segmental annular narrowing with thick interhaustral folds of the transverse colon was found by barium enema examination. This is the first report of barium study and CT findings of extrapulmonary small cell carcinoma of the colon.

Adult↗
PubMed2004

Three-dimensional reconstructed images using multidetector computed tomography in evaluation of the biliary tract.

The recent development of multidetector computed tomography (MDCT) and the parallel escalation in the capabilities of the workstation allow the use of high-quality multiplanar and three-dimensional reconstruction images. As a noninvasive technique, MDCT dedicated to the biliary tract represents an alternative to magnetic resonance cholangiography. The usefulness of three-dimensional reconstructed images using MDCT in evaluating biliary tract abnormality is illustrated.

Biliary Tract↗
PubMed2004

Neuronavigation-guided endoscopic surgery for pineal tumors with hydrocephalus.

We have applied the neuronavigation system to endoscopic biopsy and third ventriculostomy in the management of patients with a pineal tumor with hydrocephalus. With the guidance of neuronavigation, the two optimal sites of burr hole and trajectories were planned preoperatively, and the advancing endoscopic device was monitored in real time during the procedure. In our five patients, the diameters of the tumors were 2-3 cm, and the mean systemic accuracy of registration with neuronavigation was 1.2 mm. The biopsy and third ventriculostomy were performed successfully via the respective optimal burr hole and the trajectory determined using preoperative neuronavigation. There were no procedure-related complications, and none of the patients needed another procedure for CSF diversion during the follow-up periods. We present our technique which includes the application of the neuronavigation system to the biopsy and third ventriculostomy in pineal tumor with associated hydrocephalus. This technique can be performed using a simple rigid endoscope via the determined optimal entries and trajectories. The optimal preoperative planning and the intraoperative guidance by neuronavigation are thought to be able to give more chances to minimize the brain injury related to movements or deviation of endoscopic device.

Adolescent↗
PubMed2003

Web-based remote monitoring of infant incubators in the ICU.

A web-based real-time operating, management, and monitoring system for checking temperature and humidity within infant incubators using the Intranet has been developed and installed in the infant Intensive Care Unit (ICU). We have created a pilot system which has a temperature and humidity sensor and a measuring module in each incubator, which is connected to a web-server board via an RS485 port. The system transmits signals using standard web-based TCP/IP so that users can access the system from any Internet-connected personal computer in the hospital. Using this method, the system gathers temperature and humidity data transmitted from the measuring modules via the RS485 port on the web-server board and creates a web document containing these data. The system manager can maintain centralized supervisory monitoring of the situations in all incubators while sitting within the infant ICU at a work space equipped with a personal computer. The system can be set to monitor unusual circumstances and to emit an alarm signal expressed as a sound or a light on a measuring module connected to the related incubator. If the system is configured with a large number of incubators connected to a centralized supervisory monitoring station, it will improve convenience and assure meaningful improvement in response to incidents that require intervention.

Computer Communication Networks↗
PubMed2002

Development of a virtual speaking simulator using Image Based Rendering.

The fear of speaking is often cited as the world's most common social phobia. The rapid growth of computer technology has enabled the use of virtual reality (VR) for the treatment of the fear of public speaking. There are two techniques for building virtual environments for the treatment of this fear: a model-based and a movie-based method. Both methods have the weakness that they are unrealistic and not controllable individually. To understand these disadvantages, this paper presents a virtual environment produced with Image Based Rendering (IBR) and a chroma-key simultaneously. IBR enables the creation of realistic virtual environments where the images are stitched panoramically with the photos taken from a digital camera. And the use of chroma-keys puts virtual audience members under individual control in the environment. In addition, real time capture technique is used in constructing the virtual environments enabling spoken interaction between the subject and a therapist or another subject.

Computer Simulation↗
PubMed2001

Blocking of acidosis-mediated apoptosis by a reduction of lactate dehydrogenase activity through antisense mRNA expression.

Lactic acid produced from the cells is a potential cause of extra- and intracellular acidification. Due to scarce technical tools, lactic acid that leads to acidification could not be reduced and direct evidence of the relationship between metabolic lactate and apoptosis has not yet been elucidated. In this study, we designed a cellular pH regulation system in CHO cells by a reduction of lactate dehydrogenase (LDH) activity through LDH antisense mRNA expression. This inhibited lactate production and, therefore, acidification of the cytosol. Under HCO3(-)-buffered growth conditions, both the parent CHO cells and the engineered CHO cells maintained their extracellular pH and intracellular pH fairly well. However, upon acidification of the cytosol, only the parent CHO cells underwent apoptosis under HCO3(-)-free conditions. In fact, we observed a number of apoptosis-related events only in control cells, including mitochondrial dysfunction, cytochrome c release, and an increase in caspase-3 enzymatic activity.

Acidosis, Lactic↗
PubMed2001

Preoperative plasma levels of transforming growth factor beta(1) strongly predict clinical outcome in patients with bladder carcinoma.

BACKGROUND: Elevated local and circulating levels of transforming growth factor (TGF)-beta(1) have been associated with cancer invasion, progression, and metastasis. The authors tested the hypothesis that preoperative plasma TGF-beta(1) levels would independently predict cancer stage and prognosis in patients with transitional cell carcinoma (TCC) of the urinary bladder. METHODS: The study group consisted of 51 patients who underwent radical cystectomy for muscle-invasive or intravesical immuno- and/or chemotherapy refractory Tis, Ta, or T1 TCC (median follow-up, 45.7 months). Preoperative plasma levels of TGF-beta(1) were measured and correlated with pathologic features and clinical outcome. Transforming growth factor-beta(1) levels also were measured in 44 healthy men without any cancer. RESULTS: The mean preoperative plasma TGF-beta(1) level in patients who eventually developed metastases to distant (11.9 +/- 0.9 ng/mL) or regional (9.6 +/- 2.4 ng/mL) lymph nodes was significantly higher than that in patients with nonmetastatic muscle-invasive TCC (5.4 +/- 1.1 ng/mL), which, in turn, was significantly higher than that in patients with nonmetastatic Tis, Ta, or T1 TCC (4.5 +/- 1.2 ng/mL) and healthy subjects (4.5 +/- 1.2 ng/mL; P < 0.001). Preoperative plasma TGF-beta(1) level was an independent predictor of lymphovascular invasion (P = 0.002), metastases to lymph nodes (P = 0.030), disease recurrence (P = 0.009), and disease specific survival (P = 0.015). In a subgroup of patients with muscle-invasive TCC, TGF-beta(1) level was associated with disease recurrence (P = 0.005) and death from bladder carcinoma (P = 0.001). CONCLUSIONS: The authors confirm that plasma TGF-beta(1) levels are elevated in patients with muscle-invasive TCC before cystectomy. Transforming growth factor-beta(1) levels are highest in patients with bladder carcinoma metastatic to lymph nodes and are a strong independent predictor of disease recurrence and disease specific mortality.

Adult↗
PubMed2001

Predictive value of expression of transforming growth factor-beta(1) and its receptors in transitional cell carcinoma of the urinary bladder.

BACKGROUND: The purpose of this study was to describe the expression patterns of transforming growth factor (TGF)-beta(1) and its receptors in transitional cell carcinoma (TCC) of the bladder, to investigate the relation between the TGF-beta(1) and its receptors, and to determine whether altered expression of TGF-beta or its receptors is associated with disease progression and survival in patients with TCC of the bladder. METHODS: Immunohistochemical staining for TGF-beta(1) and its receptors I and II was conducted on formalin fixed paraffin embedded archival cystectomy specimens of 80 patients with bladder TCC. Immunoreactivity was categorized as either positive or negative in a blinded fashion. RESULTS: Expression of TGF-beta(1), TGF-beta-RI, and TGF-beta-RII was altered in 51 (64%), 34 (43%), and 38 (48%) specimens, respectively. Sixty (75%) specimens had altered expression of at least 1 of the 3 TGF-betas, and 26 (33%) had altered expression of all 3. Expression of the three TGF-betas was highly concordant (P < 0.018). Loss of expression of TGF-beta-RI or TGF-beta-RII was associated with invasive tumor stage (P < 0.001), high grade (P < 0.006), and lymphovascular invasion (P < 0.030). Overexpression of TGF-beta(1) was associated with invasive tumor stage only (P = 0.024). With a median follow-up of 101 months, TGF-beta-RI was an independent predictor of both disease progression (P = 0.007) and disease specific survival (P = 0.006) whereas TGF-beta(1) was an independent predictor of disease progression only (P = 0.050). Transforming growth factor-beta-RII was not independently associated with either disease progression or survival. CONCLUSIONS: Altered expression of TGF-beta(1) and its receptors is common in TCC of the bladder. Overexpression of TGF-beta(1) is associated with the loss of expression of its receptors. Transforming growth factor-beta(1) and TGF-beta-RI are independently associated with clinical outcome in patients with bladder TCC treated by radical cystectomy.

Carcinoma, Transitional Cell↗
PubMed2001

Heterozygous mice for the transforming growth factor-beta type II receptor gene have increased susceptibility to hepatocellular carcinogenesis.

The transforming growth factor-beta (TGF-beta) receptor complex and its downstream signaling intermediates constitute a tumor suppressor pathway. In many cancers, expression of TGF-beta type II receptor (TbetaR-II) is markedly decreased. In the present study, we show that the hepatocytes isolated from 15-day-old, but not 9-month-old, mice heterozygous for the deletion of the TbetaR-II gene are slightly less sensitive to the growth-inhibitory effect of TGF-beta when compared with wild-type littermates of same age. In addition, the proliferation index of hepatocytes as indicated by bromodeoxyuridine incorporation is mildly increased in the heterozygous mice. These subtle changes in cellular phenotype did not result in either gross or microscopic abnormality of the liver. The treatment of these mice with the chemical carcinogen, diethylnitrosamine, results in a significantly enhanced tumorigenesis in the liver when compared with the wild-type littermates. Our results demonstrate the gene-dosage effect of TbetaR-II and indicate that the reduced expression of TbetaR-II in mice increases susceptibility to tumorigenesis in the liver.

Animals↗
PubMed2001

Preoperative plasma levels of transforming growth factor beta(1) (TGF-beta(1)) strongly predict progression in patients undergoing radical prostatectomy.

PURPOSE: Elevated local and circulating levels of transforming growth factor beta(1) (TGF-beta(1)) have been associated with prostate cancer invasion and metastasis. We tested the hypothesis that preoperative plasma TGF-beta(1) levels would independently predict cancer stage and prognosis in patients who undergo radical prostatectomy. PATIENTS AND METHODS: The study group consisted of 120 consecutive patients who underwent radical prostatectomy for clinically localized prostate cancer (median follow-up, 53.8 months). Preoperative plasma levels of TGF-beta(1) were measured and correlated with pathologic parameters and clinical outcomes. TGF-beta(1) levels also were measured in 44 healthy men without cancer, in 19 men with prostate cancer metastatic to regional lymph nodes, and in 10 men with prostate cancer metastatic to bone. RESULTS: Plasma TGF-beta(1) levels in patients with lymph node metastases (14.2 +/- 2.6 ng/mL) and bone metastases (15.5 +/- 2.4 ng/mL) were higher than those in radical prostatectomy patients (5.2 +/- 1.3 ng/mL) and healthy subjects (4.5 +/- 1.2 ng/mL) (P <.001). In a preoperative analysis, preoperative plasma TGF-beta(1) level and biopsy Gleason sum both were predictors of organ-confined disease (P =.006 and P =.006, respectively) and PSA progression (P <.001 and P =.021, respectively). In a postoperative multivariate analysis, preoperative plasma TGF-beta(1) level, pathologic Gleason sum, and surgical margin status were predictors of PSA progression (P =.020,P =.020, and P =.022, respectively). In patients who progressed, preoperative plasma TGF-beta(1) levels were higher in those with presumed distant compared with local-only failure (P =.019). CONCLUSION: Plasma TGF-beta(1) levels are markedly elevated in men with prostate cancer metastatic to regional lymph nodes and bone. In men without clinical or pathologic evidence of metastases, the preoperative plasma TGF-beta(1) level is a strong predictor of biochemical progression after surgery, presumably because of an association with occult metastatic disease present at the time of radical prostatectomy.

Adult↗
PubMed2001

A study for watermark methods appropriate to medical images.

The network system, including the picture archiving and communication system (PACS), is essential in hospital and medical imaging fields these days. Many medical images are accessed and processed on the web, as well as in PACS. Therefore, any possible accidents caused by the illegal modification of medical images must be prevented. Digital image watermark techniques have been proposed as a method to protect against illegal copying or modification of copyrighted material. Invisible signatures made by a digital image watermarking technique can be a solution to these problems. However, medical images have some different characteristics from normal digital images in that one must not corrupt the information contained in the original medical images. In this study, we suggest modified watermark methods appropriate for medical image processing and communication system that prevent clinically important data contained in original images from being corrupted.

Algorithms↗
PubMed2001

Real-time volume rendering of four-dimensional images based on three-dimensional texture mapping.

A four-dimensional (4-D) image consists of three-dimensional (3-D) volume data that varies with time. It is used to express a deforming or moving object in virtual surgery or 4-D ultrasound. It is difficult to obtain 4-D images by conventional ray-casting or shear-warp factorization methods because of their time-consuming rendering process and the pre-processing stage necessary whenever the volume data are changed. Even when 3-D texture mapping is used, repeated volume loading is time-consuming in 4-D image rendering. In this study, we propose a method to reduce data loading time using coherence between currently loaded volume and previously loaded volume in order to achieve real-time rendering based on 3-D texture mapping. Volume data are divided into small bricks and each brick being loaded is tested for similarity to one that was already loaded in memory. If the brick passes the test, it is defined as 3-D texture by OpenGL functions. Later, the texture slices of the brick are mapped into polygons and blended by OpenGL blending functions. All bricks undergo this test. Using continuous deforming, 50 volumes are rendered in interactive time with SGI ONYX. Realtime volume rendering based on 3-D texture mapping is currently available for personal computers.

Humans↗
PubMed2001

Adaptable fuzzy C-Means for improved classification as a preprocessing procedure of brain parcellation.

Parcellation, one of several brain analysis methods, is a procedure popular for subdividing the regions identified by segmentation into smaller topographically defined units. The fuzzy clustering algorithm is mainly used to preprocess parcellation into several segmentation methods, because it is very appropriate for the characteristics of magnetic resonance imaging (MRI), such as partial volume effect and intensity inhomogeneity. However, some gray matter, such as basal ganglia and thalamus, may be misclassified into the white matter class using the conventional fuzzy C-Means (FCM) algorithm. Parcellation has been nearly achieved through manual drawing, but it is a tedious and time-consuming process. We propose improved classification using successive fuzzy clustering and implementing the parcellation module with the modified graphic user interface (GUI) for the convenience of users.

Algorithms↗
PubMed2001

Laparoscopic nephrectomy for renal cell carcinoma.

Since the first reported case of laparoscopic nephrectomy by Clayman et al. in 1991, laparoscopy is gaining acceptance as a viable alternative to open surgery for renal cell carcinoma. The benefits of laparoscopy include improved quality of life and lower incidence of perioperative morbidity. The perceived risks of laparoscopic nephrectomy for renal cell carcinoma include port-site metastasis, increased operative time, and the concern for inadequate surgical resection. The preliminary data concerning laparoscopy in renal cell carcinoma, however, indicate that rates of tumor recurrence are equivalent to open surgery while resulting in better cosmesis, decreased level of perioperative analgesic use, and decreased length of time to full convalescence.

Carcinoma, Renal Cell↗
PubMed2001

Grey matter abnormalities in obsessive-compulsive disorder: statistical parametric mapping of segmented magnetic resonance images.

BACKGROUND: Although a number of functional imaging studies are in agreement in suggesting orbitofrontal and subcortical hyperfunction in the pathophysiology of obsessive-compulsive disorder (OCD), the structural findings have been contradictory. AIMS: To investigate grey matter abnormalities in patients with OCD by employing a novel voxel-based analysis of magnetic resonance images. METHOD: Statistical parametric mapping was utilised to compare segmented grey matter images from 25 patients with OCD with those from 25 matched controls. RESULTS: Increased regional grey matter density was found in multiple cortical areas, including the left orbitofrontal cortex, and in subcortical areas, including the thalamus. On the other hand, regions of reduction were confined to posterior parts of the brain, such as the left cuneus and the left cerebellum. CONCLUSIONS: Increased grey matter density of frontal-subcortical circuits, consonant with the hypermetabolic findings from functional imaging studies, seems to exist in patients with OCD, and cerebellar dysfunction may be involved in the pathophysiology of OCD.

Adult↗
PubMed2001

Changes in dead space/tidal volume ratio and pulmonary mechanics after surfactant replacement therapy in respiratory distress syndrome of the newborn infants.

This study was performed to elucidate the mechanism of improved oxygenation after surfactant replacement therapy in respiratory distress syndrome (RDS) of the newborn infants. In 26 newborns with RDS, end tidal-CO2 tension (PetCO2), arterial blood gas analysis and pulmonary function tests were measured at baseline, 30 min, 2 hr and 6 hr after surfactant administration. The changes in dead space/tidal volume ratio (VD/VT ratio=(PaCO2-PetCO2)/PaCO2), oxygenation index and arterial-alveolar partial pressure difference for oxygen ((A-a)DO2) were elucidated and correlated with pulmonary mechanics. Oxygenation index and (A-a)DO2 improved, and VD/VT ratio decreased progressively after surfactant administration, becoming significantly different from the baseline at 30 min and thereafter with administration of surfactant. Pulmonary mechanics did not change significantly during the observation period. VD/VT ratio showed close correlation with OI and (A-a)DO2, but not with pulmonary mechanics. These results suggest that decreased physiologic dead space resulting from the recruitment of atelectatic alveoli rather than improvement in pulmonary mechanics is primarily responsible for the improved oxygenation after surfactant therapy in the RDS of newborn.

Airway Resistance↗