Biomedical subjects

S Hwang

Publications and source records attributed to S Hwang.

At least 19 recordsLinked to original sources

PubMed2007

Outcome of patients with huge hepatocellular carcinoma after primary resection and treatment of recurrent lesions.

BACKGROUND: Tumour recurrence is common after hepatic resection of hepatocellular carcinomas (HCCs) greater than 10 cm in diameter. This study evaluated the outcome of patients with huge HCC after primary resection and treatment of recurrent lesions. METHODS: A retrospective review was undertaken of clinical data for 100 patients with huge HCC who underwent liver resection. RESULTS: Mean(s.d.) tumour diameter was 13.3(3.0) cm; 80 per cent were single lesions. Systematic and non-systematic resections were performed in 80 and 20 per cent of patients respectively, with R0 resection achieved in 86 per cent. Overall 1-, 3- and 5-year disease-free survival rates were 43, 26 and 20 per cent respectively. Risk factors for HCC recurrence were resection margin less than 1 cm and macrovascular invasion. Extensive tumour necrosis of 90 per cent or more after preoperative transarterial chemoembolization was not a prognostic factor. Some 85 per cent of patients with recurrence received various treatments, and these patients had a longer post-recurrence survival than those who were not treated. Overall 1-, 3- and 5-year survival rates were 66, 44 and 31 per cent respectively. CONCLUSION: In patients with huge HCC, hepatic resection combined with active treatment for recurrence resulted in longer-term survival. Frequent protocol-based follow-up appears to be beneficial for the early detection and timely treatment of recurrence.

Adult↗

PubMed2006

Pulmonary complications following adult liver transplantation.

PURPOSE: Pulmonary complications frequently occur after liver transplantation, but the risk factors associated with them have not been fully determined. We therefore sought to identify risk factors for pulmonary complications among adult liver transplant recipients. METHODS: We retrospectively reviewed the medical records of 128 consecutive adult patients who underwent 131 liver transplantations during 2001. We evaluated the incidence, time of onset, and outcome of radiographically determined pulmonary complications, as well as the factors predictive of infectious complications. RESULTS: Postoperative chest roentgenograms detected 68 cases of pulmonary complications, including pleural effusion (n = 50), atelectasis (n = 6), pneumonia (n = 6), pulmonary edema (n = 5), and acute respiratory distress syndrome associated with pneumonia (n = 1). Of the seven patients with pneumonia, five died. On univariate analysis the risk factors predictive for pneumonia were high serum creatinine and total bilirubin, hemodialysis at the time of occurrence, and history of acute rejection and on multivariate analysis increased total bilirubin and history of acute rejection. Pulmonary complications were dependent on the medical condition at the time of occurrence rather than on the preoperative condition. CONCLUSIONS: Although the incidence of pneumonia in liver recipients was relatively low, the mortality rate in patients who developed this complication was high. High-risk patients undergoing liver transplantation thus require early diagnosis and intensive treatment to diminish the morbidity and mortality associated with pulmonary complications.

Acute Disease↗

PubMed2006

Efficacy of 6-month pretransplant abstinence for patients with alcoholic liver disease undergoing living donor liver transplantation.

PURPOSE: Questions have been raised regarding the ethics of liver transplantation in patients with alcoholic liver disease (ALD), including the fairness of cadaveric organ allocation to individuals who abuse alcohol and the efficacy of transplantation in these patients, many of whom may relapse. Living donor liver transplantation (LDLT) for ALD patients raises the similar ethical issues. ALD candidates for cadaveric liver transplants are required to abstain from alcohol for 6 months before being listed, but the efficacy of 6 months of abstinence in ALD patients receiving LDLT is not known. METHODS: We therefore determined the efficacy of 6 months of pretransplant abstinence in 15 ALD patients who underwent LDLT from February 1997 to December 2003. RESULTS: The Model for End-stage Liver Disease score was 24 +/- 10, and mean pretransplant abstinence period was 15 +/- 13 months, with 11 (73.3%) patients being abstinent for at least 6 months. Four patients received dual grafts, making the number of living donors 19: 12 children, two wives, one brother, three nephews, and one aunt. There were no unrelated donors. Three patients showed a relapse to alcohol drinking. The overall 1-, 3-, and 5-year survival rates were 100%, 100%, and 87.5%, respectively, and the cumulative 1-, 3-, and 5-year relapse rates were 6.7%, 20%, and 20%, respectively. The relapse rates in patients who did and did not maintain 6 months of abstinence were 9.1% and 50%, respectively; this difference was not significant (P = .154), likely due to the small sample size. Younger recipient age was a significant risk factor for alcohol relapse (40 +/- 8 years versus 53 +/- 6 years; P = .004). CONCLUSIONS: Pretransplant abstinence of 6 months seemed to be beneficial. For ethical reasons, a 6-month abstinence rule should be strictly observed in LDLT.

Adult↗

PubMed2006

Suitable whole blood levels 2 hours after neoral in liver transplant patients: experiences at a single center.

UNLABELLED: Whole blood levels 2 hours after Neoral (C2) administration were observed to correlate better with area under the curve (AUC(0-4)) than trough levels (C0), suggesting that C2 may be the best single time point predictor of Neoral absorption. Owing to concerns about drug toxicity due to excessive immunosuppression, C2 adjustments to target blood levels may represent an advance. The present study measured C2 and levels to determine which correlated more closely with AUC(0-4). METHODS: Between August 2003 and July 2004, 40 adult liver transplantations were performed in our center. All patients received Neoral twice daily. They were maintained at a C0 level of about 200 ng/mL. C0 levels were measured daily. C2 levels were estimated on postoperative days 3, 5, 7, 14, and 28. AUC(0-4) performed on postoperative days 3, 7, and 28 was calculated using the trapezoidal rule. RESULTS: The mean AUC(0-4), C0, C1, C2, C3, and C4 were 1100.3 +/- 484.8 ng/mL, 197.1 +/- 84.7 ng/mL, 240.7 +/- 166.2 ng/mL, 307.8 +/- 162.6 ng/mL, 302.8 +/- 138.9 ng/mL, and 300.3 +/- 142.8 ng/mL, respectively. C2 correlated with AUC(0-4) (R2 = 0.868: P < .05) better than C0 (R2 = 0.245: P < .05), C1 (R2 = 0.604: P < .05), or C4 (R2 = 0.583: P < .05). CONCLUSIONS: Neoral dose monitoring according to a mean C2 range of 307.8 +/- 162.6 ng/mL correlated better with AUC(0-4). Further studies are required to determine suitable C2 levels in liver transplant patients.

Adult↗

PubMed2006

Reappraisal of seventh-day syndrome following living donor liver transplantation.

Seventh-day syndrome (7DS) is characterized by sudden failure of a liver graft that had been working normally at about 1 week after transplantation, without an identifiable cause. A nonnegligible percentage of cadaveric liver transplants have shown this type of acute graft failure, whereas 7DS has not been reported after living donor liver transplantation (LDLT). Among 580 adult LDLT recipients in our institution between 1997 and 2003, 3 (0.5%) showed clinical sequences typical of 7DS. All three recipients showed similar but unique clinical sequences, consisting of initial uneventful recovery, dramatic rise of serum liver enzyme levels about 1 week later despite potent antirejection therapy, and subsequent graft loss. Liver biopsy findings were compatible with massive hemorrhagic necrosis. Sustained fever lasting for 2 days preceded deterioration of liver function. All three patients died prior to the opportunity for retransplantation. Our findings suggest that, as in cadaveric donor liver transplantation, 7DS can also occur following LDLT and that a preceding episode of sustained fever may be a prodrome of 7DS although its pathogenesis is yet poorly understood.

Adult↗

PubMed2006

The role of biomaterials in stem cell differentiation: applications in the musculoskeletal system.

The capabilities of stem cells continue to be revealed, leading to excitement regarding potential new therapies. Regenerative medicine is an area in which stem cells hold great promise for overcoming the challenge of limited cell sources for tissue repair. Biomaterials play an important role in directing tissue growth and may provide another tool to manipulate and control stem cell behavior. Biomaterials are made from natural or synthetic polymers and can be processed into three-dimensional scaffolds designed to promote cell proliferation and/or differentiation that ultimately produces new tissue. Stem cells will have a significant impact on the fields of regenerative medicine and tissue engineering as a powerful cell source that will work, in conjunction with biomaterials, to treat tissue and organ loss. Herein, we survey our latest research on applying embryonic stem (ES) cells to hydrogel biomaterials for engineering musculoskeletal tissues, emphasizing the unique biomaterial requirements of ES cells for differentiation and tissue development.

Animals↗

PubMed2006

Characteristics of sludge reduction in an integrated pretreatment and aerobic digestion process.

In this study, integrated pretreatments and aerobic digestion processes were investigated in order to provide a feasible alternative that can achieve effective sludge reduction. An ozone treatment in the presence of ionic manganese, a catalyst, increased the sludge reduction ratio three times higher than that of a single ozonation, presumably due to an increase in OH radical production. The ozone treatment yielded the effective sludge reduction ratio with an increasing ozone dosage, and an effective dosage of the catalyst was found to be 4 mg-Mn/g-TS. When a mechanical pretreatment and an ozone/catalyst were applied in a series, the integrated process, even at a half mechanical intensity and a half level of ozone dosage, showed higher and faster sludge reduction than each single process did. In addition, the integrated pretreatment process showed the highest dewaterability of the treated sludges. A ratio of sludge cake generation, which was newly introduced to quantify overall performance of sludge treatment processes, showed that the integrated pretreatment followed by the aerobic digestion yielded approximately a half of the sludge cake volume compared to the single aerobic digestion. Therefore, the integrated pretreatment can be a feasible method for the effective reduction of total suspended solid and the final volume.

Aerobiosis↗

PubMed2006

Short communication: Cultivation of Lentinus edodes mycelia using whey permeate as an alternative growth substrate.

The major objective of this research was to use whey permeate as an alternative growth medium for the cultivation of mycelia of the edible mushroom Lentinus edodes and to find an optimum condition for solid-state cultivation. Response surface analysis was applied to determine the combination of substrate concentration (40 to 60 g of lactose/L), temperature (20 to 30 degrees C), and pH (4 to 6) resulting in a maximal mycelial growth rate. The radial extension rates, estimated by measuring the diameters of growing colonies on the Petri dishes, were used as the growth rate of the mycelia at different conditions. The conditions predicted to maximize the mycelial growth of 6.41 +/- 0.47 mm/d were determined to be 40 g of lactose/L, temperature 23.6 degrees C, and pH 5.0. It was concluded that a partial cubic equation could accurately model the response surface of, and predict optimal growth conditions for, L. edodes mycelia using whey permeate because the model prediction agreed with the experimental growth rate, 6.39 +/- 0.22 mm/d. The results suggest that whey permeate could be utilized as a growth substrate for the cultivation of mycelia from the edible mushroom L. edodes, enhancing the use of this by-product by the cheese manufacturing industry.

Hydrogen-Ion Concentration↗

PubMed2005

Anatomic variation of the right hepatic artery and its reconstruction for living donor liver transplantation using right lobe graft.

We analyzed the anatomy and reconstruction of the right hepatic artery (RHA) in 96 cases of adult-to-adult living donor right liver transplantations, during 2002. Most right livers had a single orifice (n = 185, 96%). Seven right livers (4%) showed multiple arteries, namely a replaced artery in five cases and accessory arteries in two cases. Three liver grafts had two separate orifices: both arterial stumps were reconstructed in one case, and accessory arteries were ligated in two cases because of sufficient back bleeding. The mean diameter of the graft RHA was 2.4 mm (1-4). More than 60% (59 of 96) of graft arteries were anastomosed with distal branches of recipient RHA for size matching. Eleven graft arteries were anastomosed to vessels other than the RHA, namely the left hepatic artery [LHA] in eight right gastroepiploic artery in three: for size matching in five and due to previous injury of RHA in six. Five cases showed significant size-mismatches of more than twofold. The median follow-up period was 270 days. In one patient, an intramural thrombus developed on postoperative day 3 requiring a revision of the anastomosis. In another patient, arterial stenosis occurred on postoperative day 16 a time when collateral arteries had developed. The overall complication rate related to arterial reconstruction was 2%. In conclusion, with precise knowledge of the anatomy, an adequate selection of recipient arterial stump, and an experienced technique, a desirable result may be achieved in right lobe transplantation.

Adult↗

PubMed2005

Refined suture techniques to prevent bleeding from accidental slippage of vascular clamps during living donor hepatectomy.

Accidental slippage of vascular clamps during living donor hepatectomy can induce brisk bleeding and even imperil the donor. After practicing more than 1000 cases of living donor hepatectomy, the investigators realized that specialized suture techniques were important to secure the vascular closure to prevent unnecessary bleeding. For secure division of intrahepatic vein branches, we devised a continuous penetration suture method in which the orders of procedures were changed to clamping-closure-cut sequence. For secure division of the main and accessory hepatic vein branches from the inferior vena cava, we applied stay sutures at each corner and midpoint of the hepatic vein stump so as not to permit its slippage. After application of these methods, we did not experience any episode of accidental clamp slippage. We are sure that these suture techniques are beneficial to prevent unnecessary bleeding during living donor hepatectomy and to make surgeons feel at ease during the living donor operation.

Blood Loss, Surgical↗

PubMed2005

Analysis of community structures in anaerobic processes using a quantitative real-time PCR method.

The methanogenic community structures of four different anaerobic processes were characterized using a quantitative real-time PCR with group-specific primer and probe sets targeting the 16S rRNA gene (rDNA). The group specific primer and probe sets were developed and used to detect the orders Methanosarcinales, and the families Methanosarcinaceae and Methanosaetaceae. Two separate sets targeting the domains Archaea and Bacteria were also used. Each microbial population in different anaerobic processes was determined and the relative abundance in the system was compared with each other. Dominant methanogenic populations and the community structures in the processes were varied by hydraulic retention time and acetate concentration. This indicates that the real-time PCR method with the primer and probe sets is a promising tool to analyze community structures in anaerobic processes.

Acetates↗

PubMed2004

Extrapulmonary tuberculosis as a mimicker of neoplasia.

Despite the efforts for control and eradication of tuberculosis, new cases of the disease are diagnosed daily. The diagnosis of tuberculosis is easily made when the classical features of pulmonary necrotizing granulomatous inflammation are seen. However, extrapulmonary lesions may clinically and radiographically mimic a neoplastic process, and this may lead to misdiagnosis and delay in treatment. We studied 6 patients by aspiration biopsy, all recent immigrants and immunocompetent, who presented with weight loss and fatigue. Of these, 5 patients had a mass. One patient presented with a lytic lesion of bone. In all cases the clinical diagnosis was neoplasia. In all aspirates, the smears showed necrotic debris with neutrophils. No neoplastic cells or granulomas were seen. All cases were signed out descriptively with no specific diagnosis. A search for acid-fast organisms leading to the correct diagnosis of tuberculosis was prompted by clinical investigations that revealed pulmonary lesions, or by repeat aspiration biopsy, which showed granulomatous inflammation. Tuberculosis when present in atypical forms is still a challenging diagnosis. The finding of necrotic debris in a needle biopsy without the clinical signs of an abscess should prompt a search for acid-fast bacilli, since the correct diagnosis will eliminate a needless surgical procedure and will lead to timely and appropriate therapy.

Adult↗

PubMed2004

Intraoperative assessment of hepatic venous congestion with direct clamping of the hepatic vein trunk for living donor liver transplantation.

We devised a hepatic vein clamping method to assess the amount of hepatic venous congestion (HVC) before liver transection. From February 2003 to May 2003, this method was applied to 5 of 58 living donor livers especially to assess donor safety. The left portal vein and proper hepatic artery as well as the middle hepatic vein (MHV)-left hepatic vein (LHV) trunk were clamped simultaneously to assess the HVC in the remnant right lobe before performing extended left lobectomy. As three donors demonstrated the extent of the HVC equivalent to about 40% of the right lobe volume (RLV), their operations proceeded according to the preoperative plan. The territory of HVC after liver transection was the same as that observed with direct clamping of the hepatic vein. However, one donor showed massive HVC more than 50% of RLV and the operative plan was adjusted to harvest only the left lobe without the MHV trunk for donor safety. To assess the HVC in the remnant left lobe, the isolated LHV trunk was occluded after clamping the donor's proper hepatic artery. The whole left lobe except for a small area at the anterior portion of the medial segment became discolored on LHV clamping: the opposite demarcation appeared on MHV clamping. The amount of HVC was so small that we harvested the right lobe with the MHV trunk. All donors and recipients recovered uneventfully. We believe that this direct clamping method makes the assessment of HVC feasible before parenchymal transection of a donor liver.

Adult↗

PubMed2004

A case report of split liver transplantation for two adult recipients in Korea.

We report a case of split liver transplantation (SLT) for two adult recipients, which was the first successful case in Korea. The brain-dead donor was a 22-year-old man weighing 65 kg, but his liver volume was estimated as 2120 mL on computed tomographic volumetry. As it seemed to be too large for a 60-kg recipient candidate, SLT was planned after assessment of lobar liver volume and middle hepatic vein anatomy. The right lobe was mobilized first and the liver parenchyma transected along the right border of the middle hepatic vein. The 1240-g right lobe (segments 5 to 8) graft was implanted into a 57-year-old male patient with acute-on-chronic liver failure in the same manner as a living-donor graft. After that, routine procedures of cadaveric multiorgan procurement were performed. The 670-g left lobe (segments 1 to 4) with a retrohepatic vena cava, common bile duct, and aortic patch was implanted into another 37-year-old male recipient. These two recipients recovered uneventfully surviving 12 months to date. We integrated the surgical techniques learned from hundreds of adult-to-adult living donor liver transplants into this first trial of two adult SLT.

Adult↗

PubMed2004

Antidepressants and suicidal behaviour in unipolar depression.

OBJECTIVE: To compare the rates of suicidal behaviour during vs. after discontinuation of treatment with antidepressants, and to determine the comparative rates of suicidal behaviour for patients maintained on tricyclic (TCA) vs. selective serotonin reuptake inhibitor (SSRI) antidepressants. METHOD: Charts were reviewed for 521 patients with major depressive disorder and/or dysthymic disorder. Periods of active treatment or discontinuation with SSRIs or TCAs were determined. Rates of completed suicide, suicide attempts, and hospitalization for suicidality were analyzed. RESULTS: There was greater than a five-fold increase in risk for suicidal behaviour after discontinuation of antidepressant treatment (P < 0.0001). The rates of suicidal behavior during treatment with SSRIs or TCAs were similar. CONCLUSION: Suicidal behaviour in unipolar depressed patients treated with antidepressants increases substantially after medication discontinuation. This effect occurred in both patients who were maintained on SSRIs and TCAs. The findings support a possible protective effect on suicidal behaviour for both SSRIs and TCAs.

Adult↗

PubMed2004

The status of structural genomics defined through the analysis of current targets and structures.

Structural genomics--large-scale macromolecular 3-dimenional structure determination--is unique in that major participants report scientific progress on a weekly basis. The target database (TargetDB) maintained by the Protein Data Bank (http://targetdb.pdb.org) reports this progress through the status of each protein sequence (target) under consideration by the major structural genomics centers worldwide. Hence, TargetDB provides a unique opportunity to analyze the potential impact that this major initiative provides to scientists interested in the sequence-structure-function-disease paradigm. Here we report such an analysis with a focus on: (i) temporal characteristics--how is the project doing and what can we expect in the future? (ii) target characteristics--what are the predicted functions of the proteins targeted by structural genomics and how biased is the target set when compared to the PDB and to predictions across complete genomes? (iii) structures solved--what are the characteristics of structures solved thus far and what do they contribute? The analysis required a more extensive database of structure predictions using different methods integrated with data from other sources. This database, associated tools and related data sources are available from http://spam.sdsc.edu.

Computational Biology↗

PubMed2004

Clustering protein sequence and structure space with infinite Gaussian mixture models.

We describe a novel approach to the problem of automatically clustering protein sequences and discovering protein families, subfamilies etc., based on the theory of infinite Gaussian mixtures models. This method allows the data itself to dictate how many mixture components are required to model it, and provides a measure of the probability that two proteins belong to the same cluster. We illustrate our methods with application to three data sets: globin sequences, globin sequences with known three-dimensional structures and G-protein coupled receptor sequences. The consistency of the clusters indicate that our method is producing biologically meaningful results, which provide a very good indication of the underlying families and subfamilies. With the inclusion of secondary structure and residue solvent accessibility information, we obtain a classification of sequences of known structure which both reflects and extends their SCOP classifications. A supplementray web site containing larger versions of the figures is available at http://public.kgi.edu/approximately wid/PSB04/index.html

Amino Acid Sequence↗

PubMed2004

Optimizing volatile fatty acid production in partial acidogenesis of swine wastewater.

This research has been conducted based on the fact that acetic and butyric acids are favorable substrates for methanogens, and that a low level of propionic acid production during acidogenesis minimizes the inhibition effect on methanogenic growth. Raw swine wastewater was pretreated with ammonia stripping to enhance acidogenesis. The ammonia nitrogen concentration of less than 1.2 g/L did not significantly affect the biochemical acidogenic potential of swine wastewater. For acidogenesis of swine wastewater, a set of experiments were carried out to produce short chain volatile fatty acids (VFA) in laboratory-scale continuously stirred tank reactors. The production of acetic, propionic, and butyric acids associated with simultaneous changes in hydraulic retention time (HRT) and temperature was investigated. Response surface methodology was successfully applied to approximate the responses of the VFA productions. The optimum physiological conditions where the maximum acetic and butyric acids production occurred were 2.4 days HRT at 34 degrees C and 2.1 days HRT at 35 degrees C, respectively. The propionic acid production linearly increased as both HRT and temperature increased.

Acetic Acid↗