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Biomedical subjects

J W Huang

Publications and source records attributed to J W Huang.

At least 19 recordsLinked to original sources
PubMed2001

Direct determination of sinigrin in mustard seed without desulfatation by reversed-phase ion-pair liquid chromatography.

Reversed-phase ion-pair liquid chromatography has been investigated for directly analyzing sinigrin in mustard seed without desulfatation. After extraction by phosphate buffer (pH 7.0) from the grind-pastes of inactivated-myrosinase mustard seeds, sinigrin was first isolated through deproteinization and centrifugation, followed by filtration and injection into the chromatographic system. A reversed-phase C18 column was used to separate the sinigrin with an eluent of acetonitrile (ACN)-water (20:80) containing 0.02 M tetrabutylammonium (TBA) as the counter ion at pH 7.0. Detection was carried out with an UV detector operated at 227 nm. Factors affecting the chromatographic separation and quantitative determination, such as concentrations of TBA and ACN, and pH, were studied. The linear dynamic range is larger than three orders of magnitude and the detection limit is 0.045 mg/L. The RSD is around 3% and the recovery is 85% (3% RSD, n = 3).

Calibration↗
PubMed2001

Dipyridamole inhibits TGF-beta-induced collagen gene expression in human peritoneal mesothelial cells.

BACKGROUND: Peritoneal matrix accumulation is characteristic of peritoneal fibrosis (PF). Continuous ambulatory peritoneal dialysis (CAPD) patients who had persistent transforming growth factor-beta (TGF-beta) in their drained effluent had an increased risk of PF. We previously reported that TGF-beta stimulates the expression of types I and III collagen mRNA in cultured human peritoneal mesangial cells (HPMCs), which may predispose them to develop PF. Pharmacological interventions to attenuate TGF-beta-stimulated matrix accumulation in HPMC may have therapeutic potential for the treatment of PF. The SMAD family and the extracellular signal-regulated protein kinase (ERK1/2, p44/p42) pathways have been shown to participate in TGF-beta signaling. Our current study identified these signal pathways in HPMCs and investigated the molecular mechanisms involved in the inhibitory effects of dipyridamole on TGF-beta-induced collagen gene expression in HPMCs. METHODS: HPMCs were cultured from human omentum by an enzyme digestion METHOD: Expression of collagen alpha1(I) mRNA was determined by Northern blotting. The SMAD proteins and the ERK1/2 activity were determined by Western blotting. RESULTS: TGF-beta-stimulated collagen alpha1(I) mRNA expression of HPMC was inhibited by dipyridamole in a dose-dependent manner. Smad2 and ERK1/2 were activated in response to TGF-beta; however, TGF-beta had little effect on the protein expression of Smad4. The addition of PD98059, which blocked activation of ERK1/2, suppressed TGF-beta-induced collagen alpha1(I) mRNA expression in a dose-dependent manner. At a concentration that inhibited collagen gene expression (17 microg/mL), dipyridamole suppressed ERK1/2 activation by TGF-beta. In contrast, the same concentration of dipyridamole had no effect on TGF-beta-induced activation of Smad2. CONCLUSION: Dipyridamole inhibits TGF-beta-induced collagen gene expression in HPMC through modulation of the ERK pathway. Our study of dipyridamole may provide therapeutic basis for clinical applications in the prevention of PF.

Cells, Cultured↗
PubMed2001

Comparison of infectious complications in peritoneal dialysis patients using either a twin-bag system or automated peritoneal dialysis.

BACKGROUND: Automated peritoneal dialysis (APD) and twin-bag (TB) systems are two major peritoneal dialysis (PD) modalities. Published data comparing the infectious complications of these modalities is limited. Subjects and methods. Ninety-five patients using APD (the APD group) and 117 patients using TB system (the TB group) were recruited. Among them, 35 patients used both modalities. The two groups' clinical characteristics, incidences of infectious complications, and the time intervals to first PD-related infection were compared. RESULTS: Clinical characteristics, incidence of exit-site infection (ESI), and time intervals to first ESI were similar in the TB and APD groups. The incidence of peritonitis in the APD group (1.22 episodes/100 patient-months) was significantly (P < 0.001) lower than that of the TB group (2.28 episodes/100 patient-months). Using the Cox proportional hazard model, APD was found to have a lower risk of peritonitis relative to TB systems, with marginal significance (RR 0.58, P = 0.051). CONCLUSION: APD was found to have a lower peritonitis rate than the TB system. Since reducing the peritonitis rate helps to maintain technical survival during PD, from this viewpoint, APD may be preferred for patients undergoing PD, unless contraindicated.

Adult↗
PubMed2000

Airway cross section strongly influences alveolar plateau slope of capnograms for smaller tidal volumes.

We compared the predictions of the single path convection-diffusion model (SPM) and the well-mixed single acinus model (SAM) with the normalized slopes (NS) of experimentally measured volumetric capnograms in which VT was varied in three healthy spontaneously breathing adults. For values of VT greater than 15 ml/kg, the tidal volume penetrates deep into the acinar airways, mixing by molecular diffusion is rapid and the predictions of the SAM and SPM both agree with the experiment. The SPM however shows much better agreement with the experimental NS data than does the SAM for values of VT less than 10 ml/kg. The explanation for the departure of the SAM from the observed experimental data, at small VT, is that it represents the limiting case (of well-mixed alveolar gas) for the SPM, only at large VT, where the assumption of rapid mixing is most accurate. We conclude that in general, gas phase diffusivity and total acinar airway cross sectional area variation with cumulative volume into the lung are essential to realistically model airway gas exchange between VT and FRC and to obtain agreement with experimental data under the widest range of breathing conditions.

Adult↗
PubMed2000

Trace Metals' abnormalities in hemodialysis patients: relationship with medications.

A multicenter collaborative study was performed to investigate the prevalence of abnormal blood contents of 6 trace metals, copper (Cu), zinc (Zn), aluminum (Al), lead (Pb), cadmium (Cd), and mercury (Hg), in hemodialysis (HD) patients and to analyze their relationship with the medications, such as CaCO3, Ca acetate, Al containing phosphate-binding agents, 1,25-dihydroxy vitD3, 1-hydroxy vitD3, and erythropoietin (EPO), as well as hematocrit level, by chi-square statistics. From 6 medical centers in Taiwan, we included 456 patients in maintenance HD for more than 4 months for this study, and they had continued the previously mentioned medications for at least 3 months. Blood samples were collected before initiating HD, and atomic absorption spectrophotometry was used to measure plasma levels of Cu, Zn, and Al as well as whole blood levels of Pb, Cd, and Hg. Three hundred seventy-five (78%) of the HD patients had low plasma Zn levels, that is, <800 microg/L, and the mean (+/-SD) concentration was 705.8 (+/-128.23) microg/L in all subjects. One hundred forty-one (31%) of the HD patients had high plasma Al, that is, >50 microg/L, and the mean (+/-SD) was 44.30 (+/-28.28) microg/L in all subjects. Three hundred thirty-three (73%) of the dialysis patients had high Cd levels, that is, >2.5 microg/L, and the mean (+/-SD) was 3.32 (+/-1.49) microg/L in all subjects. The majority of HD patients had normal blood levels of Cu, PB, and Hg. Only 21 (4. 6%), 5 (1.1%), and 3 (0.06%) patients had elevated blood levels of Cu, Pb, and Hg, respectively. Their mean (+/-SD) blood concentration of Cu, Pb, and Hg were 1,049.78 (+/-233.25) microg/L, 7.45 (+/-3.95) microg/dL, and 3.17 (+/-25.56) microg/L, respectively. Three patients had elevated plasma Hg concentrations, that is, 546, 12.6, and 24.0 microg/L, respectively. In the 152 normal healthy age and sex matched control group, the blood levels of Al, Cd, and Pb were all significantly lower than the HD patients. However, the levels of Cu and Zn were higher in the control group. The Hg level was not significantly different in both groups. There was no statistical difference between patients with normal and abnormal blood levels of trace metals in various medications except Al containing phosphate binder. The Al containing phosphate binder users had significantly higher plasma Al levels (54.71 +/- 26.70 versus 41.15 +/- 28.03 microg/L, p < 0.001) and hematocrit levels (29.61 +/- 4.61 versus 27. 81 +/- 3.91, p < 0.0005). There was no statistical correlation between erythropoietin (EPO) dose and hematocrit level in these patients. In conclusion, the blood level of trace metals of these HD patients except Al was not related to their medications. However, caution must be exercised in interpreting this result as dose and duration of medication; efficiency of HD and water treatment may play an important role. Otherwise, environmental factors, diet, and the aging process may contribute to the trace metal burden in uremia. Thus, Zn and Cu are abundant in seafood, and Cd is abundant in contaminated plants such as rice.

Acetates↗
PubMed2000

Natural changes in peritoneal equilibration test results in continuous ambulatory peritoneal dialysis patients: a retrospective, seven year cohort survey.

We conducted a retrospective, 7 year cohort survey to examine the natural changes in peritoneal equilibration test (PET) results in patients with long-term uneventful continuous ambulatory peritoneal dialysis (CAPD). Thirty-two (17 males, 15 females) patients on CAPD with two or more standard PETs performed more than 6 months apart, in the absence of peritoneal insult, were included. Changes and pattern of PET results were evaluated by the dialysate to plasma ratio of creatinine (D:P-cre), the fourth h dialysate to instilled glucose ratio (D4:Do) and ultrafiltration volume (UF, ml). The subgroups included high (H), high-average (HA), low-average (LA), or low (L) transporters with the dividing ratios (D:P-cre) of >0.81, >0. 65 to 0.81, >0.5 to 0.65, and <0.5, respectively. The median D:P-cre significantly decreased (p = 0.04), but neither the D4:Do nor the final median UF significantly decreased. The change in D:P-cre was strongly and inversely correlated with the initial D:P-cre value (r = -0.68; p < 0.05). A similar relationship was found between the change in the final D4:Do and the initial D4:Do (r = -0.752; p < 0. 01) and between the change in the final UF and the initial UF (r = -0.875; p < 0.01). No correlation was found between the change in D:P-cre and the age of the patient, the time interval between PETs, monthly dialysate glucose exposure, or underlying diabetes/non-diabetes. The final peritoneal transport pattern was altered with 5 (15.6%) patients remaining in the extreme subgroups (H or L) and, by contrast, 84.4% (27/32) of the patients now in the averaged (HA or LA) groups (p < 0.01, chi2 test). We demonstrated a natural "centralization" migration of PET results after long-term uneventful CAPD, which may help to explain why patients with extreme PET characteristics, that is, H or L, continued to do well on CAPD.

Adult↗
PubMed2000

Clinical features of and risk factors for fungal peritonitis in peritoneal dialysis patients.

BACKGROUND AND PURPOSE: Fungal peritonitis (FP) is a serious complication for peritoneal dialysis (PD) patients and can result in technical failure and mortality. Catheter removal remains the mainstay of treatment. This study sought to identify the risk factors for FP in order to facilitate the prevention of this catastrophic complication. METHODS: A total of 246 patients who received long-term PD from 1985 to 1998 were included in this retrospective study. Twenty episodes of FP occurred in 19 patients. The clinical characteristics, pathogens, treatment modalities, and outcomes of the FP episodes were retrospectively reviewed. The FP incidence in various demographic and clinical groups, classified according to sex, age, education, and underlying cause of uremia, were compared with the Poisson test. RESULTS: Thirteen episodes of FP were caused by yeast, and the remaining episodes were caused by Aspergillus spp. Age, sex, and education did not affect the FP incidence. Lupus patients (969 patient-months) had a higher incidence of FP than patients with other underlying diseases (p < 0.05). The 19 FP patients also had a higher incidence of bacterial peritonitis than other PD patients (p < 0.01). Among the 20 FP episodes, 14 (70%) were preceded by antibiotic use, and eight (40%) developed during hospitalization. Steroids were used at the time of FP in five of six lupus patients. Seven patients (37%) died within 1 month after diagnosis of FP. Five patients were able to remain on PD after FP, but only three patients were able to maintain catheter placement. CONCLUSION: The risk factors for FP identified in this study include the use of antibiotics and steroids, underlying lupus, frequent occurrence of bacterial peritonitis, and hospitalization. Antifungal therapy may allow the catheter to be kept in place in a few patients, but catheter removal should be considered in patients whose FP is refractory to medical treatment.

Adult↗
PubMed2000

Incidence of exit-site infection with various exchange systems in continuous ambulatory peritoneal dialysis.

BACKGROUND AND PURPOSE: The disconnect twin-bag (TB) system was first introduced in Taiwan for use as an exchange system in continuous ambulatory peritoneal dialysis (CAPD) in 1995. Following its introduction, the incidence of CAPD-associated peritonitis declined, but the incidence of exit-site infection (ESI) increased. To determine the cause of the increase in ESI incidence after the introduction of the TB system, this study compared the incidence of ESI among patients using the O set, ultraviolet antiseptic (UV) device, and the TB system. METHODS: A total of 170 patients who had received CAPD for more than 3 months were enrolled in this study. Poisson test and Kaplan-Meier survival analysis were used to compare the ESI incidence and ESI-free catheter survival among patients using the O set, UV device, or TB system. Cox stepwise forward proportional hazard analysis was used to assess the impact of sex, education, cause of uremia, age, and type of exchange system on ESI. RESULTS: The incidences of ESI differed significantly among patients using the three exchange systems, with 20.9, 13.8, and 4.0 episodes per 100 patient-years for patients using the TB system, O set, and UV device, respectively. New patients using the TB system also had a shorter mean interval of ESI-free catheter survival than those using the UV device (26.9 vs 58.8 months, p = 0.002). In the Cox stepwise forward proportional hazard analysis, non-lupus patients had a lower risk of developing ESI than lupus patients (relative risk [RR] 0.40, p = 0.03). The RR of ESI in patients using the UV device was also lower than in those using the TB system (RR 0.15, p < 0.01). CONCLUSION: In this study, use of the TB system was associated with a higher incidence of ESI. The increased ESI incidence may be related to the heavier mini-transfer set of the TB system. Therefore, special attention should be given to fastening the mini-transfer set tightly during the exchanging procedure to prevent traction on the exit-site, which is associated with an increased incidence of subsequent ESI.

Adult↗
PubMed1999

Pneumoperitoneum caused by a perforated peptic ulcer in a peritoneal dialysis patient: difficulty in diagnosis.

Peritonitis due to viscus perforation in peritoneal dialysis (PD) patients can be catastrophic. We describe the first reported case of perforated peptic ulcer (PPU) in a PD patient. This 78-year-old man presented with a 1-day history of mild abdominal pain. He had been receiving nocturnal intermittent PD for 2 years and had ischemic heart disease and cirrhosis of the liver. Pneumoperitoneum and peritonitis were documented, but the symptoms were mild. The "board-like abdomen" sign was not noted. Air inflation and contrast radiography indicated a perforation in the upper gastrointestinal tract, and laparotomy disclosed a perforation in the prepyloric great curvature. Unfortunately, the patient died during surgery. This case illustrates that the "board-like abdomen" sign may be absent in PD patients with PPU because of dilution of gastric acid by the dialysate. Free air in the abdomen, although suggestive of PPU, is also not uncommon in PD patients without viscus perforation. Because PD has to be discontinued after laparotomy and exploratory laparotomy may be fatal in high-risk patients, other diagnostic methods should be used to confirm viscus perforation before surgery. PPU, which can be proved by air inflation and contrast radiography, should be suspected in PD patients with pneumoperitoneum and peritonitis.

Aged↗
PubMed1999

Depth of anesthesia estimation and control.

A fully automated system was developed for the depth of anesthesia estimation and control with the intravenous anesthetic, Propofol. The system determines the anesthesia depth by assessing the characteristics of the mid-latency auditory evoked potentials (MLAEP). The discrete time wavelet transformation was used for compacting the MLAEP which localizes the time and the frequency of the waveform. Feature reduction utilizing step discriminant analysis selected those wavelet coefficients which best distinguish the waveforms of those responders from the nonresponders. A total of four features chosen by such analysis coupled with the Propofol effect-site concentration were used to train a four-layer artificial neural network for classifying between the responders and the nonresponders. The Propofol is delivered by a mechanical syringe infusion pump controlled by Stanpump which also estimates the Propofol effect-site and plasma concentrations using a three-compartment pharmacokinetic model with the Tackley parameter set. In the animal experiments on dogs, the system achieved a 89.2% accuracy rate for classifying anesthesia depth. This result was further improved when running in real-time with a confidence level estimator which evaluates the reliability of each neural network output. The anesthesia level is adjusted by scheduled incrementation and a fuzzy-logic based controller which assesses the mean arterial pressure and/or the heart rate for decrementation as necessary. Various safety mechanisms are implemented to safeguard the patient from erratic controller actions caused by external disturbances. This system completed with a friendly interface has shown satisfactory performance in estimating and controlling the depth of anesthesia.

Algorithms↗
PubMed1999

Necrotizing fasciitis caused by Serratia marcescens in two patients receiving corticosteroid therapy.

Necrotizing fasciitis (NF), a devastating soft tissue infection, is rarely attributed to Serratia marcescens. We here report two patients with S. marcescens NF, both of whom had underlying renal disease and had been receiving corticosteroid therapy. The first patient, a 40-year-old man with systemic lupus erythematosus and uremia on prednisolone therapy, developed fulminant cellulitis and septic shock 1 month after a skin biopsy for cutaneous vasculitis of the left foot. The cellulitis evolved to NF, and blood and necrotic tissue cultures both grew S. marcescens. The patient completely recovered after debridement and ceftazidime therapy. The second patient, a 73-year-old man receiving prednisolone therapy for nephrotic syndrome, developed right leg cellulitis that evolved to NF. Blood and necrotic tissue cultures both grew S. marcescens. After aggressive debridement and ciprofloaxcin therapy, the NF improved. However, the patient died of aspiration pneumonia and massive gastrointestinal bleeding 1 month later. These findings illustrate that S. marcescens should be considered as a potential pathogen causing NF in susceptible hosts.

Adult↗
PubMed1998

Immunoblot analysis of components of barley recognized by IgE antibodies in sera from pig farm workers.

Components of the crude extract of barley, recognized by IgE antibodies in sera from 132 pig farm-workers in southern Taiwan, were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Among the sera tested, 43 (32.6%) showed IgE reactivity to 15 components of barley with molecular mass ranging from 148000 to 14000 daltons (Da). Heterogeneity in the IgE-binding patterns of the samples tested was observed. However, the major antigen appears to be the component with about 37 kDa, in 32 (74.4%) of the 43 immunoblot-positive serum samples. Furthermore, components with about 55 and 67 kDa which reacted with 26 (60.5%) and 18 (41.9%) of the positive samples, respectively. These might also be considered as important allergens of the flour made from entire seeds of barley. The results suggest that barley may be considered to play a role in the IgE-mediated occupational respiratory disorders and the 37 kDa component has also been shown to be the major allergen.

Agricultural Workers' Diseases↗
PubMed1998

H2-uptake activity, spectra, reduction potentials, and kinetics of iron release on the surface of iron core from Azotobacter vinelandii bacterial ferritin.

Bacterial ferritin from Azotobacter vinelandii (AvBFo) has a function in H2 uptake. The Fe3+ reduction on the surface of the iron core from AvBFo is accompanied simultaneously by H2 uptake, with a maximum activity of H2 uptake of 450 H2/AvBFo. A reduction potential of -402 mV for iron reduction on the surface of the core is found. A shift to the red the protein absorbance peaks ranging from 280 to 290 nm is observed between pH 5 and 9 under 100% H2 reduction. The reduction potential for iron release becomes negative at a rate of 0.025 mV/Fe2+ released. The kinetics of iron release on the surface of the core is a first-order reaction.

Azotobacter vinelandii↗
PubMed1998

Multiple-drug hemodynamic control using fuzzy decision theory.

A fuzzy-logic-based, automated drug-delivery system has been developed and validated on a nonlinear canine circulatory model for managing hemodynamic states. This controller features: 1) a fuzzy decision analysis module for patient status determination by assessing cardiac index, systemic vascular resistance index, and pulmonary vascular resistance index and 2) a fuzzy hemodynamic management module utilizing dopamine, phenylephrine, nitroprusside, and nitroglycerin for regulating mean arterial pressure, mean pulmonary arterial pressure, and cardiac output. A rule-based drug delivery scheduling program has been devised and incorporated to execute the therapeutic strategy as recommended by the decision analysis module. Compared to the existing controllers, this system is able to achieve a faster response time with a more secured and effective regulation. The simulation results have demonstrated the feasibility of the decision analysis process for automated management of the arterial and venous circulation with an expanded arsenal of pharmacological agents.

Animals↗