Biomedical subjects

J J Hwang

Publications and source records attributed to J J Hwang.

At least 19 recordsLinked to original sources

PubMed2004

Radio frequency ablation of small renal tumors:: intermediate results.

PURPOSE: With evolving radio frequency technology, the clinical application of radio frequency ablation (RFA) has been actively investigated in the treatment for small renal tumors. We present our intermediate patient outcomes after RFA. MATERIALS AND METHODS: Since January 2001, 17 patients with a total of 24 hereditary renal tumors ranging from 1.2 to 2.85 cm were treated with RFA using the 200 W Cool-tip RF System (Radionics, Burlington, Massachusetts) under laparoscopic (9) or percutaneous (8) guidance and had a minimum 1-year followup. A percutaneous approach was considered unsuitable if kidney tumors were contiguous to bowel, ureter or large vessels. Treatment eligibility criteria included an average tumor diameter of less than 3.0 cm, tumor growth during 1 year and solid appearance with contrast enhancement (HU change greater than 20) on computerized tomography (CT). Postoperative followup consisted of CT with and without intravenous contrast, and renal function assessment at regular intervals. RESULTS: Median patient age was 38 years (range 20 to 51). At a median followup of 385 days (range 342 to 691), median tumor or thermal lesion diameter decreased from 2.26 to 1.62 cm (p = 0.0013), and only 1 lesion (4%), which was located centrally near the hilum, exhibited contrast enhancement (HU change greater than 10) on CT at 12 months. Of the 15 renal tumors ablated laparoscopically, 13 were in direct contact with the bowel and 2 were abutting the ureter, necessitating mobilization before RFA. Laparoscopic ultrasound was used to guide radio frequency electrode placement and monitor the ablation process in these cases. Operative time and intraoperative blood loss (mean +/- standard mean of error) were 243 +/- 29 minutes and 67 +/- 9 cc, respectively. In 1 patient whose ureter was adherent to the tumor a ureteropelvic junction obstruction developed after laparoscopic RFA, requiring open repair. CONCLUSIONS: At the minimum 1-year followup 23 of 24 ablated tumors lacked contrast uptake on CT, meeting our radiographic criteria of successful RFA treatment. RFA treatment of small renal tumors using the Radionics system appears to result in superior treatment outcomes compared to those of earlier series with lower radio frequency power generators. A high wattage generator might attain more consistent energy deposition with subsequent cell death in the targeted tissue due to less convective heat loss.

Adult↗

PubMed2003

Electrical characterization of metal-molecule-silicon junctions.

Direct assembly of molecules onto silicon surfaces is of particular interest for potential employment in hybrid organic-semiconductor devices. In the study we report here, aryl diazonium salts were used to assemble covalently bound molecular groups on a hydride-passivated, oxide-free n-type Si(111) surface. The reaction of 4-(trimethylsilylethynyl)benzenediazonium tetrafluoroborate generates a molecular layer of 4-(trimethylsilylethynyl)phenylene (TMS-EP) on the n++-Si(111) surface. The monolayer modifies the electrical properties of the interface and exhibits nonlinear current-voltage characteristics, as compared with the ohmic behavior observed from metal-n++-Si(111) junctions. The result of current-voltage measurements at variable temperatures (from 300 to 10 K) on samples made with the TMS-EP molecule does not show significant thermally-activated transport, indicating that tunneling is the dominant transport mechanism. The measured data is compared to a tunneling model.

Electric Conductivity↗

PubMed2002

Biodistribution study of [99mTc] TRODAT-1 alone or combined with other dopaminergic drugs in mice with macroautoradiography.

A 99mTc labeled tropane derivative, [99mTc] TRODAT-1 (2beta-((N,N'-bis(2-mercaptoethyl) ethylene diamino)methyl), 3beta-(4-chlorophenyl) tropane), is a potential dopamine transporter (DAT) imaging agent for the central nervous system. To better understand the binding localization of [99mTc] TRODAT-1 both in the brain and the body, whole-body macroautoradiography (WBAR) was used in this study. The effect of DAT competing drugs, such as levadopa (L-DOPA), N-methyl-2beta-carbomethoxy-3beta-(4fluorophenyl)tropane (CFT, WIN 35,428) and methylphenidate, on the biodistribution of [99mTc] TRODAT-1 were also included in this study. Doses of 150 MBq [99mTc] TRODAT-1 were injected into normal male ICR mice through the caudal veins. For comparison, mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), L-DOPA, methylphenidate and CFT, respectively, were also investigated under the similar protocols. One and a half hours after [99mTc] TRODAT-1 injection, the mice were sacrificed. Whole-body autoradiography was performed immediately after sacrifice. Both frontal and sagittal sections showed that the liver and mucosa of stomach had the highest uptake of [99mTc] TRODAT-1. Other binding sites included the periphery of the spinal cord and the epithelium of the intestine. In the brain, autoradiographic imaging obtained from frontal sections showed symmetrical uptakes of [99mTc] TRODAT-1 in bilateral striata. Remaining binding sites include olfactory bulbs, thyroid gland, and salivary gland. The autoradiographic imaging obtained from sagittal sections showed a similar biodistribution. Mice treated with MPTP or L-DOPA showed no significant difference in the uptake of [99mTc] TRODAT-1 in bilateral striata, as compared to those of the control. In CFT or methylphenidate-treated mice, DAT binding sites were almost completely inhibited. These data showed that [99mTc] TRODAT-1 has potential clinical use for neurological investigation, such as Parkinson's and similar diseases.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed2002

Estimation of mean-glandular dose from monitoring breast entrance skin air kerma using a high sensitivity metal oxide semiconductor field effect transistor (MOSFET) dosimeter system in mammography.

Estimation of mean-glandular dose (MGD) has been investigated in recent years due to the potential risks of radiation-induced carcinogenesis associated with the mammographic examination for diagnostic radiology. In this study, a new technique for immediate readout of breast entrance skin air kerma (BESAK) using high sensitivity MOSFET dosimeter after mammographic projection was introduced and a formula for the prediction of tube output with exposure records was developed. A series of appropriate conversion factors was applied to the MGD determination from the BESAK. The study results showed that signal response of the high sensitivity MOSFET exhibited excellent linearity within mammographic dose ranges, and that the energy dependence was less than 3% for each anode/filter combination at the tube potentials 25-30 kV. Good agreement was observed between the BESAK and the tube exposure output measurement for breasts thicker than 30 mm. In addition, the air kerma estimated from our prediction formula provided sufficient accuracy for thinner breasts. The average MGD from 120 Asian females was 1.5 mGy, comparable to other studies. Our results suggest that the high sensitivity MOSFET dosimeter system is a good candidate for immediately readout of BESAK after mammographic procedures.

Female↗

PubMed2001

Paternity determination when the alleged father's genotypes are unavailable.

In paternity testing using the DNA evidence, analysis of the deficiency case when the DNA profiles of the alleged father are not available is different from that of the case with complete evidence. In this paper, we describe how to evaluate and determine the paternity in the deficiency case, by comparing the paternity indexes of the true father and the falsely non-excluded man.

Chromosome Mapping↗

PubMed2001

Relation of Chlamydia pneumoniae infection in Taiwan to angiographically demonstrated coronary artery disease and to the presence of acute myocardial infarction or unstable angina pectoris.

Reports of the association of Chlamydia pneumoniae (C. pneumoniae) infection with coronary artery disease (CAD) are scarce in the Oriental population. We therefore conducted a case-control study to explore this issue in Taiwan. There were 242 consecutive subjects (166 men and 76 women) who underwent cardiac catheterization at the National Taiwan University Hospital Cardiac Catheterization Laboratory. Patients with CAD (n = 156) had > or = 1 coronary artery lesion of > 50% diameter stenosis on angiography. Controls (n = 86) had no demonstrable CAD angiographically. Antibodies to C. pneumoniae were tested by using an enzyme-linked immunosorbent assay. The prevalence of antibodies to C. pneumoniae was as follows: immunoglobulin-G (IgG), 50% (122 of 242 patients); immunoglobulin-A (IgA), 72% (176 of 242 patients); and either IgG or IgA, 79% (192 of 242 patients ). The odds ratio (OR) for CAD with either IgG or IgA was 1.4 (95% confidence interval [CI] 0.7 to 2.7, p = 0.31). After adjusting for the known CAD risk factors, the OR decreased to 0.8 (95% CI 0.3 to 2.1, p = 0.60). The OR for unstable angina or acute myocardial infarction with the presence of either IgG or IgA was 0.5 (95% CI 0.2 to 1.1, p = 0.08) and 0.4 ( 95% CI 0.1 to 1.0, p = 0.049) after adjusting for other risk factors. These results suggest a high prevalence of C. pneumoniae infection in Taiwan. However, C. pneumoniae infection is not associated with angiographically documented CAD, and, in contrast, is a negative predictor for the development of acute coronary syndromes.

Aged↗

PubMed2001

Evaluation of DNA match probability in criminal case.

The new emphasis on quantification of evidence has led to perplexing courtroom decisions and it has been difficult for forensic scientists to pursue logical arguments. Especially, for evaluating DNA evidence, though both the genetic relationship for two compared persons and the examined locus system should be considered, the understanding for this has not yet drawn much attention. In this paper, we suggest to calculate the match probability by using coancestry coefficient when the family relationship is considered, and thus the performances of the identification values depending on the calculation of match probability are compared under various situations.

Bias↗

PubMed2001

Functional role of matrix metalloproteinases (MMPs) in mammary epithelial cell development.

The extracellular matrix (ECM) is an important regulator of mammary epithelial cell (MEC) function and is remodeled by matrix metalloproteinases (MMPs). To investigate the significance and regulation of MMP activity in normal MEC, we utilized a primary culture model in which rat MEC were grown three dimensionally within a reconstituted basement membrane (RBM) in defined serum-free medium. Zymograms of culture medium demonstrated that five major gelatinases of 97, 80, 74, 69, and 65 kDa were secreted by MEC and were distinct from gelatinases of RBM origin. Based on molecular weight, p-aminophenylmercuric acid activation, immunoblotting with MMP-specific antibodies, inhibition by EDTA, a peptide containing the prodomain sequence of MMP (TMRKPRCGNPDVAN) and two synthetic MMP inhibitors (BB-94 and CGS 27023A), these were classified as inactive and active forms of MMP-9 and MMP-2. The maximal MMP activities occurred when MEC were in a rapid proliferation and branching phase and declined after they underwent functional differentiation. Known regulators of MEC growth and differentiation were evaluated for their ability to modulate gelatinase activity in primary culture. Secretion of one or both MMPs was inhibited by EGF, TGFalpha, prolactin, and hydrocortisone and stimulated by progesterone. Furthermore, the functional significance of MMPs was demonstrated since three MMP inhibitors blocked branching morphogenesis elicited by the absence of hydrocortisone. Additionally, two synthetic MMP inhibitors not only inhibited epithelial cell growth but also inhibited normal alveolar development of the MEC. Finally, these drugs were found to enhance MMP secretion from MEC, although the activity of the secreted MMPs was inhibited as long as the drug was present.

Animals↗

PubMed2001

Non-amplification of an allele of the D8S1179 locus due to a point mutation.

During a population study of 128 Korean families (626 persons) with the AmpF/STR Profiler Plus PCR amplification system, we found an unusual homozygous genotype at the D8S1179 locus in 4 families. Therefore, a new pair of primers was designed for the D8S1179 locus from GenBank data (GenBank Accession No. G08710) to evaluate the cause. The newly designed primers amplified alleles that were not amplified with the AmpFlSTR Profiler Plus PCR amplification system. We sequenced alleles of the family members who had non-amplified alleles and we found a G-to-A transition at the position of the 147th base of the GenBank sequence.

Alleles↗

PubMed2001

Genomics and the pathophysiology of heart failure.

Heart failure is not a single disease entity, but a syndrome with various causes, including hypertension, ischemic and congenital heart disease, cardiomyopathy, and myocarditis. Because of the multiple etiologies and secondary adaptations contributing to heart failure, the study of the cellular and molecular mechanisms underlying the development and progression of this syndrome has been rather challenging. Much has been learned about the remodeling processes in heart failure, which involve complex interactions among numerous mediators in signaling and regulatory pathways. The Human Genome Project and related projects have provided a preliminary database for a genome-wide analysis of complex polygenic disorders such as heart failure. With the aid of expressed sequence tag technology and microarray applications, both known and previously uncharacterized genes involved in the induction and regression of cardiac hypertrophy and its progression to heart failure can be analyzed simultaneously. Deciphering the complexity of sequence-structure-function relationships in heart failure is a goal for the future, and will require advances in structural biology, proteomics, and computational technology. In this review, we summarize the cellular and molecular aspects of heart failure, and how recent applications of genomic technologies have been successful in achieving a more complete portrait of gene expression in this pathologic state.

Animals↗

PubMed2001

Differential lipogenic effects of cilostazol and pentoxifylline in patients with intermittent claudication: potential role for interleukin-6.

Cilostazol, a novel oral phosphodiesterase inhibitor, has shown consistent improvement in exercise tolerance in patients with intermittent claudication (IC). In addition to this effect, cilostazol has previously been shown to have beneficial effects on the dyslipidemia, i.e., combination of high triglycerides with low high-density-lipoprotein cholesterol (HDL-C) levels. Interleukin-6 (IL-6) suppresses the activity of lipoprotein lipase, which modulates the metabolism of triglycerides and HDL-C. To determine whether a reduction of IL-6 contributes to the improvement of lipid profiles, we prospectively investigated the effect of cilostazol (n=16, 100 mg, twice daily) on the changes of lipid profiles and on the association with the changes of IL-6 compared with those of pentoxifylline (n=16, 400 mg, bid) in patients with IC. After eight weeks of administration of cilostazol to patients with IC, walking distances were increased, associated with a 29% decrease in plasma triglycerides and a 13% increase in HDL-C. No significant changes of lipid profiles in the pentoxifylline and placebo groups were observed although a similar improvement in walking distances was achieved in the pentoxifylline group. IL-6 levels were significantly reduced in patients receiving cilostazol as compared with those receiving placebo or pentoxifylline. The cilostazol-induced changes in the IL-6 were positively related to those of triglycerides in the cilostazol group (r=0.63, P<0.05) and negatively related to those of HDL-C (r=-0.55, P<0.05). These findings suggest that in addition to consistent improvement of exercise tolerance, cilostazol may improve lipid profiles by reducing IL-6 release. However, pentoxifylline did not affect lipid profiles although a similar improvement of maximal walking distance (MWD) was achieved.

Aged↗

PubMed2001

Biodosimetry using chromosomal translocations measured by FISH in a population chronically exposed to low dose-rate 60Co gamma-irradiation.

PURPOSE: To evaluate the cumulative gamma-radiation personal exposure by analysing lymphocyte chromosome translocations using FISH painting and to compare FISH-derived biodoses with those derived from retrospective physical dose reconstruction in residents receiving chronic low dose-rate gamma-irradiation while living in radio-contaminated buildings. MATERIALS AND METHODS: Chromosome translocation frequencies were evaluated by scoring 933 to 3077 metaphases under fluorescence microscope for each of the five male and four female exposed individuals after they had relocated from the radioactive environment for 34-82 months. FISH painting was conducted using kits of whole-chromosome probes for chromosomes 1, 2 and 4 in orange and 3, 5 and 6 in green and counter-stained with 4',6-diamidino-2-phenylindole (DAPI). The retrospective dose estimation termed Taiwan Cumulative Dose (TCD) was conducted by assessment using detailed information of historical exposure and the environmental radioactivity for each apartment during previous residency. RESULTS: A total of 20 244 well-prepared metaphases were scored. Biodoses were calculated from the translocation frequencies and physical doses were estimated from detail questionnaires for each individual. The translocation frequencies measured ranged from 2.2x10(-3) to 26.8x10(-3) translocations per cell and the dose equivalent from 52.2 to 992.2mSv. A good correlation was observed between the physical and biodoses. A plot of TCD against FISH-derived doses produced D(fish) =0.65 D(TCD), when fitted by a linear model, and D(fish) = 0.53 D(TCD)+ 1.26x10(-4 ) D(2)(TCD), when fitted with a linear-quadratic model. Given the scatter in the data and the extremely small quadratic dose contribution, neither model could be ruled out. CONCLUSION: Chromosome translocations provide a valid method of dose estimation in extremely protracted low dose-rate gamma-radiation exposure. Validation of the TCD method by FISH-measured translocations supports the use of TCD for epidemiological studies.

Adolescent↗

PubMed2001

Sensitization of a tumor, but not normal tissue, to the cytotoxic effect of ionizing radiation using Panax notoginseng extract.

The aim of the present study was to investigate any sensitization effect of the Panax notoginseng extract (PNE) and the purified Saponin (Rb1) on the radiation response of an experimental tumor (KHT sarcoma) in mice, in comparison with any effects on a normal tissue (bone marrow). PNE at a concentration of 0.1-100 mg/kg produced an increase in tumor radiosensitivity. The sensitization effect was maximal at 10 mg/kg and at 30 minutes after injection. Higher doses were toxic to the bone marrow stem cells. Similarly Rb1 at a concentration 0.001 to 1 mg/kg also produced an increase in tumor radiosensitivity, with maximum effect at 1 mg/kg. Higher doses were not toxic to the bone marrow stem cells in this case. Radiosensitization factors were calculated as ratios of D0 (the radiosensitivity parameter), and these were highly significant for the tumor and very similar for both compounds at the doses used, namely 1.18-1.19. There was no significant effect for bone marrow stem cells (sensitization factors of 0.99 +/- 0.01 for both compounds). The differential effect on tumor, and the magnitude of the radiosensitization, suggest that further purified or synthetic versions of this extract may be useful not only in vascular-related diseases but also in cancer therapy.

Animals↗

PubMed2001

Differential gene expression in a DNA double-strand-break repair mutant XRS-5 defective in Ku80: analysis by cDNA microarray.

The ability of cells to rejoin DNA double-strand breaks (DSBs) usually correlates with their radiosensitivity. This correlation has been demonstrated in radiosensitive cells, including the Chinese hamster ovary mutant XRS-5. XRS-5 is defective in a DNA end-binding protein, Ku80, which is a component of a DNA-dependent protein kinase complex used for joining strand breaks. However, Ku80-deficient cells are known to be retarded in cell proliferation and growth as well as other yet to be identified defects. Using custom-made 600-gene cDNA microarray filters, we found differential gene expressions between the wild-type and XRS-5 cells. Defective Ku80 apparently affects the expression of several repair genes, including topoisomerase-I and -IIA, ERCC5, MLH1, and ATM. In contrast, other DNA repair-associated genes, such as GADD45A, EGR1 MDM2 and p53, were not affected. In addition, for large numbers of growth-associated genes, such as cyclins and clks, the growth factors and cytokines were also affected. Down-regulated expression was also found in several categories of seemingly unrelated genes, including apoptosis, angiogenesis, kinase and signaling, phosphatase, stress protein, proto-oncogenes and tumor suppressors, transcription and translation factors. A RT-PCR analysis confirmed that the XRS-5 cells used were defective in Ku80 expression. The diversified groups of genes being affected could mean that Ku80, a multi-functional DNA-binding protein, not only affects DNA repair, but is also involved in transcription regulation. Our data, taken together, indicate that there are specific genes being modulated in Ku80- deficient cells, and that some of the DNA repair pathways and other biological functions are apparently linked, suggesting that a defect in one gene could have global effects on many other processes.

Animals↗

PubMed2001

Determination of 8-oxoguanine in individual cell nucleus of gamma-irradiated mammalian cells.

8-Oxoguanine, through its ability to mispair bases other than cytosine, is assumed to be one of the most potent premutagenic lesions in nuclear DNA damaged by reactive oxygen radicals. In this study, we examine whether the presence of residual 8-oxoguanine can be detected in mammalian cells after exposure to ionizing radiation. MOLT-4 human leukemia cells and CHO-K1 Chinese hamster cells were acutely irradiated in vitro with 0, 0.2, 0.4, 0.6 and 1.0 Gy gamma radiation at room temperature. The amounts of 8-oxoguanine and total DNA in the cell nucleus were detected by fluorescein-isothiocyanate (FITC)-labeled avidin, which binds specifically and directly to 8-oxoguanine, and propidium iodide, respectively. The intensity ratios between these two fluorescent dyes were then taken as indices to measure the content of 8-oxoguanine within individual cells. We found an apparent dose-dependent increase in the amount of 8-oxoguanine accumulated in cells of both lines. Moreover, the content of 8-oxoguanine decreased from 2 to 20 h after irradiation in CHO-K1 cells, which may reflect the time-dependent repair processes at the 8-oxoguanine lesions. This novel approach may provide a sensitive tool for in situ measurement of 8-oxoguanine in cells or even in the human body after exposure to ionizing radiation.

Animals↗

PubMed2001

Dyspnea and palpitation during pregnancy.

OBJECTIVES: Dyspnea and palpitation are common features of pregnancy. While several theories have been put forward to explain the etiology of gestational dyspnea and palpitation, there have been few systemic studies of its incidence, severity and time-course in a group of normal women. METHODS: We interviewed postpartum women, within 3 days after delivery, about dyspnea and palpitation. Separately from this interview, we performed 24-hour ECG monitoring for obstetric patients with palpitation before delivery. RESULTS: The subjects interviewed were 261 women, of whom 37.5 percent and 11.5 percent experienced dyspnea and palpitation, respectively. These symptoms had tendency to increase to term. The presence of arrhythmias could be documented in only 22% of patients having 24-hour Holter monitoring. CONCLUSION: Dyspnea and palpitation were common among normal pregnant women and had a tendency to increase to term.

Adult↗

PubMed2001

Pneumopericardium after bronchoscopic carbon dioxide laser surgery--a case report.

A female baby sustained pneumopericardium after bronchoscopic CO2 laser surgery for tracheal stenosis. Perioperative pneumopericardium though rare is a life-threatening condition in babies. The symptoms are usually not specific such as hypotension, bradycardia, muffled heart sound, cardiovascular collapse, etc. The causes and clinical findings of pneumopericardium were reviewed, as are the radiographic features so as to differentiate the condition from pneumomediastinum. Early recognition of pneumopericardium is important, because emergent pericardiocentesis may be required if there is clinical evidence of cardiac tamponade.

Bronchoscopy↗

PubMed2000

Motherless case in paternity testing.

In paternity test using the DNA evidence, the analysis of the deficient case that the DNA profiles of mother or alleged father are not available is different from that of the trio case analyzed routinely. However, the motherless case that the genotypes of mother is not available has been requested and analyzed like the trio case. In this paper, we compared the motherless case and the trio case through the mean exclusion chance describing the probability of exclusion for a genetic marker system and the distribution of the probability of paternity calculated using the three current methods. We have also shown a case which can be falsely discriminated if it were requested in the analysis of the motherless case, and conclude that the analysis of the motherless case should be carefully conducted and the level for the discrimination should be different from that of the trio case.

DNA Fingerprinting↗