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C H Huang

Publications and source records attributed to C H Huang.

At least 91 records · Page 5Linked to original sources
PubMed2000

Structure activity studies on group C meningococcal polysaccharide-protein conjugate vaccines: effect of O-acetylation on the nature of the protective epitope.

A series of group C meningococcal polysaccharide-tetanus toxoid (GCMP-TT) conjugates were prepared as vaccines with varying percentages of O-acetylation at the C-7 and C-8 positions of sialic acid residues in the polysaccharide (PS). The immune response in mice was highly dependent on the degree of O-acetylation. Less O-acetylation resulted in higher serum bactericidal activity (SBA) towards the O-acetylated (OA) meningococcal strain, C11. In addition, since an unconjugated de-O-acetylated (dOA) GCMP vaccine was previously shown to be highly immunogenic in humans, we had chosen this dOA form to couple with TT by reductive amination for clinical evaluation. This conjugate vaccine was shown to be well-tolerated and highly immunogenic in adults, children, and infants in the UK. To understand the nature of the GCMP protective epitope, a series of spectroscopic and serological studies were conducted, using high resolution H-NMR spectroscopy at 500 MHz and competitive inhibition SBA assays. The dOA GCMP was 10-1000 times better at inhibiting the SBA for an OA strain than the OA GCMP, suggesting that the GCMP-based protective epitope on the bacterium exists in a dOA form. In addition, SBA for an OA strain is highly correlated with dOA GCMP-specific IgG. NMR data on freshly isolated GCMP indicated that, on the surface of the organism, most of the O-acetylation exists at position C-8, with some regions containing dOA or OA C-7 sialic acid. After extraction of PS and storage in solution, most of the O-acetyl groups migrate to C-7, leaving an epitope that is conformationally related, but not quite identical (due to the presence of the O-acetyl group), to the one contained in the dOA PS. We speculate that the role of the O-acetyl group at the C-8 position of the PS on the organism is to form less immunogenic epitopes, or mask the protective epitope, and thus escape immune surveillance. The dOA form of the vaccine may therefore provide better protection against group C meningococcal disease than the OA form by eliciting a greater proportion of functional antibodies that are directly aimed at the protective epitope.

Acetylation↗
PubMed2000

Adrenal myelolipoma--report of two cases.

Adrenal myelolipoma, which is composed of hematopoietic and adipose elements, is a rare benign tumor. Most adrenal myelolipomas are asymptomatic and are found incidentally. We report two cases of adrenal myelolipoma. One was a middle-aged woman with right flank pain. Tumor size increased 8 years later. The other patient was a 63-year-old man presenting with right flank soreness. The right adrenal tumor was found by abdominal sonography. Both of them received adrenalectomy to relieve symptoms and the pathologic results showed adrenal myelolipoma. The clinical, radiologic and pathologic characteristics of these two cases are discussed together with a review of the literature.

Adrenal Gland Neoplasms↗
PubMed2000

The effect of fluvastatin on fibrinolytic factors in patients with hypercholesterolemia.

Several studies have shown cardiovascular benefit in treating hypercholesterolemia with HMG-CoA reductase inhibitor. However, in addition to the lowering of cholesterol, the beneficial effects of this inhibitor reflect other pharmacological activities. Whether these beneficial effects are partly mediated by changes in fibrinolytic factors remains to be proven, since clinical studies on the effects of HMG-CoA reductase inhibitors on fibrinolytic factors have not yielded consistent results. The purpose of this study was to evaluate the effects of fluvastatin on fibrinolytic factors in hypercholesterolemic patients. After 6 weeks on a low-fat, low-cholesterol diet, 23 outpatients known to have primary hypercholesterolemia with low density lipoprotein cholesterol (LDL-C) > or = 130 mg/dl with at least 2 risk factors or fasting LDL-C > or = 160 mg/dl were selected for the study. Venous blood samples were collected at baseline and at 8 weeks after fluvastatin therapy (40 mg/day) to measure of tissue plasminogen activator (t-PA), plasminogen activators inhibitor-1 (PAI-1), fibrinogen, D-dimer and lipid profile. After 8 weeks of therapy, fluvastatin reduced serum cholesterol by 11% (261.9 mg/dl vs 233.2 mg/dl, P < 0.01) and LDL-C by 22% (191.9 mg/dl vs 149.3 mg/dl, P < 0.01). D-dimer was significantly decreased (0.38 ng/L vs 0.28 ng/L, P = 0.02) and tPA, PAI-1 and fibrinogen tended to decrease after therapy. Fluvastatin therapy improved fibrinolytic profile; the result of this study may in part explain the benefit of HMG-CoA reductase inhibitor on cardiovascular system other than lipid lowering.

Aged↗
PubMed1999

Relationship between chimerism and tolerance in a kidney transplantation model.

The persistence of donor leukocytes in recipients of organ allografts has been associated with long-term graft acceptance. However, it remains unclear whether this peripheral donor cell microchimerism plays an active role in graft acceptance or is simply a consequence of the maintenance of sufficient immunosuppression to avoid rejection. A model of kidney transplantation between swine leukocyte Ag (SLA)-matched miniature swine, in which tolerance can be established with or without immunosuppressive treatment, has been used to study the correlation between donor leukocyte chimerism and kidney graft acceptance. SLA-identical kidney transplants were performed from animals positive for an allelic pig leukocyte Ag to animals negative for this marker. SLA-identical kidney transplant recipients given a 12-day course of cyclosporine (CyA) (n = 3) became tolerant, showing stable serum creatinine levels (1-2 mg/dl) after cessation of CyA treatment. Donor cell chimerism (0.2-0.7%) was present by FACS in all three animals with peak levels detected at 3 wk. Two control animals receiving SLA-identical kidney grafts without CyA also showed stable serum creatinine levels and became tolerant. However, in neither of these animals could donor leukocytes be detected in the peripheral blood beyond 1 wk following transplantation. In one additional control animal, ureteral obstruction occurred at day 10, and was associated with additional peripheral chimerism, presumably related to inflammation rather than to immune status. These results indicate that the persistence of donor cell chimerism is not a requirement for the maintenance of tolerance to organ allografts in this model.

Animals↗
PubMed1999

Unusual clinical presentation of upper urothelial carcinoma in Taiwan.

BACKGROUND: The unusual clinical picture of transitional cell carcinoma (TCC) in Taiwan appears to be different from that reported elsewhere. METHODS: The authors reviewed their experience of 135 cases of pathologically proven TCC of the upper urinary tract. Data regarding the gender ratio and clinical presentation were analyzed. RESULTS: The male to female ratio was found to be 1 to 1.3, showing a slight female predominance. The ratio of TCC of the renal pelvis to TCC of the ureter to TCC of the bladder was noted to be approximately 1.1:0.9:8.0. TCC of the renal pelvis accounted for 10.7% of all urothelial TCC, and for approximately 40% of all renal carcinomas. CONCLUSIONS: The results of the current study found that the gender incidence and ratio of renal pelvis TCC to all renal carcinomas are different in Taiwan compared with data presented in the majority of other studies.

Adolescent↗
PubMed1999

Hydrocarbon chain packing and the effect of ethanol on the thermotropic phase behavior of mixed-chain phosphatidylglycerols.

Previous studies in this laboratory have delineated the relationship between the acyl chain asymmetry of mixed-chain phosphatidylcholines and the effect of ethanol concentration ([EtOH]) on their melting behavior (Li et al., Biophys J., 70 (1996) 2784-2794). This present investigation extends these findings to another phospholipid family by using high-resolution differential scanning calorimetry (DSC) to characterize the effect of ethanol concentration on the main phase transition temperature (Tm) of five molecular species of mixed-chain phosphatidylglycerol (PG). For C(14):C(18)PG, C(15):C(17)PG, C(16):C(16)PG, and C(17):C(15)PG, a biphasic profile in the Tm versus [EtOH] plot was observed, and the minimum in the plot for each PG occurred at 33, 15, 19, and 36 mg/ml, respectively. This biphasic behavior is typical of phospholipids whose acyl chain asymmetry is fairly small. For C(18):C(14)PG, only a linear decrease in the Tm was observed as a function of ethanol concentration; this effect is characteristic of highly asymmetric phospholipids. Our DSC results obtained with mixed-chain PG in the presence of ethanol demonstrate that the acyl chain asymmetry of the five lipids studied can be ranked as follows: C(15):C(17)PG<C(16):C(16)PG<C(14):C(18)PG<C(17):C(15)PG<C(18):C(14)PG , confirming independent results from this laboratory that the overall acyl chain structure of PG in the hydrated gel phase is opposite to that detected in the single crystals. In fully hydrated bilayers, the acyl chain conformation of PG is most likely to be similar to that of phosphatidylcholine.

Calorimetry, Differential Scanning↗
PubMed1999

Thermotropic phase behavior of mixed-chain phosphatidylglycerols: implications for acyl chain packing in fully hydrated bilayers.

In this communication we report the first systematic investigation of the thermodynamic properties of fully hydrated mixed-chain phosphatidylglycerols (PG) using high-resolution differential scanning calorimetry (DSC). The crystal structure of dimyristoylphosphatidylglycerol shows an acyl chain conformation that is nearly opposite to that of phosphatidylcholine (PC). In PC, the sn-1 chain is straight while the sn-2 chain contains a bend; for PG, the sn-1 contains a bend while the sn-2 chain is in the all-trans conformation (R.H. Pearson, I. Pascher, The molecular structure of lecithin dihydrate, Nature, 281 (1978) 499-501; I. Pascher, S. Sundell, K. Harlos, H. Eibl, Conformational and packing properties of membrane lipids: the crystal structure of sodium dimyristoylphosphatidylglycerol, Biochim. Biophys. Acta, 896 (1987) 77-88). If the structure of PG found in the single crystal can be extrapolated to that in the fully hydrated gel-state bilayer, the observed difference in acyl chain conformations implies that modulation of the acyl chain asymmetry will have an opposite effect on the thermotropic phase behavior of PG and PC. For example, it is expected, based on the crystal structures, that C(15):C(13)PG should have a higher main phase transition temperature (Tm) than C(14):C(14)PG, and C(13):C(15)PG should have a lower Tm than C(14):C(14)PG. However, our DSC studies show clearly that the expectation is not borne out by experimental data. Rather, the Tm values of C(15):C(13)PG, C(14):C(14)PG, and C(13):C(15)PG are 18.2 degrees C, 23.1 degrees C, and 24.4 degrees C, respectively. Several other PGs, each with a unique acyl chain composition, have also been studied in this laboratory using high-resolution DSC. It is shown that the acyl chain conformation of fully hydrated PG in general is nearly opposite to that seen in the PG crystal structure.

Calorimetry, Differential Scanning↗
PubMed1999

Molecular basis for Rh(null) syndrome: identification of three new missense mutations in the Rh50 glycoprotein gene.

Rh(null) is a rare autosomal recessive disorder characterized by an absence of Rh antigens and a varying degree of hemolytic anemia and spherostomatocytosis. We report studies of two Japanese Rh(null) cases and describe three new missense mutations of RHAG, the locus that encodes Rh50 glycoprotein and modulates Rh antigen expression. In Rh(null)(HT), RHAG harbored in exon 6 two G-->A transitions, GTT-->ATT and GGA-->AGA, which cause Val(270)-->Ile and Gly(280)-->Arg substitutions, respectively. These missense mutations were cotransmitted from the propositus to the children and were predicted to reside in endoloop 5 and transmembrane (TM) segment 9, respectively. In Rh(null)(WO), RHAG contained in exon 9 a single G-->T transversion, GGT-->GTT, which caused a Gly(380)-->Val missense change in TM12 segment. The G-->T transversion, which is located at the +1 position of exon 9, had also affected pre-mRNA splicing and caused partial exon skipping. Although both Rh(null) cases had a structurally normal RH antigen locus, hemagglutination and immunoblotting showed no expression of Rh antigens or proteins. These results correlate each mutation with a structural defect in the respective TM domain of Rh50 glycoprotein.

Amino Acid Sequence↗
PubMed1999

Analysis of ultrahigh molecular weight polyethylene failure in artificial knee joints: thermal effect on long-term performance.

The mechanism resulting in damage to and failure of ultrahigh molecular weight polyethylene (UHMWPE) tibial inserts was investigated on clinically retrieved components. The severity of the subsurface damage increased with the length of time that the component had been implanted. A theoretical analysis was developed to account for the generation of subsurface damage based on a heat transfer model. Friction generates surface heat during articulation of total knee systems. Due to the cooling effect of body fluid on the surface, the rise in temperature on the UHMWPE surface is lower than that below the surface. The peak temperature was estimated to occur on a plane positioned about 1 to 2 mm below the surface. This result was similar to the bulk temperature variation observed during in vivo and in vitro studies by other investigators. Although the difference in temperature on and below the surface is only a few degrees, the thermal effect becomes apparent after a long time and may be explained by the viscoelastic behavior of polymers: the temperature-time equivalence. It is therefore suggested that this thermal effect is another contributory factor to material damage, in addition to high stress and oxidative degradation (in appropriate cases). Therefore, any technological efforts aimed at improving the performance of artificial joint prostheses should minimize the thermal effects at the subsurface of the articular components.

Aged↗
PubMed1999

Tea consumption: fluid intake and bladder cancer risk in Southern Taiwan.

OBJECTIVES: To determine whether tea consumption and intake of other beverages increases bladder cancer risk. METHODS: A case-control study was conducted in Kaohsiung, Taiwan between August 1996 and June 1997. Index patients studied were consecutive patients with histologically confirmed, newly diagnosed bladder cancer in two major hospitals. For each patient, 4 controls were selected from patients with non-neoplastic and nonurologic diseases undergoing surgical operations in the same hospital and individually matched by sex, age, and date of admission. Using a structured questionnaire, a trained interviewer interviewed 40 patients and 160 controls. Conditional logistic regression analysis adjusting for ethnicity, family history, and smoking status and matching variables were used to estimate the odds ratio (OR) and 95% confidence interval (CI). RESULTS: Tea consumption overall was associated with increased bladder cancer risk (OR 3.29, 95% CI 1.34 to 8.05). Compared with non-tea drinkers, the odds ratios of bladder cancer for oolong tea drinkers was 3.00 (95% CI 1.20 to 7.47); for non-oolong tea drinkers (black and/or other green tea), it was 14.86 (95% CI 2.13 to 103.83). The risk was greater among those who began to drink tea before age 40 (OR 9.50, 95% CI 2.39 to 37.75) and those who had been drinking tea for more than 30 years (OR 17.75, 95% CI 3.00 to 105.17). Coffee, tap water, and alcohol consumption were associated with a slightly increased risk, and both soy juice and rice juice consumption were associated with reduced risk; none of these odds ratio estimates were statistically significant, however. CONCLUSIONS: Our results suggest that tea consumption is associated with an increased risk of bladder cancer.

Aged↗
PubMed1999

A new approach of designing the tibial baseplate of total knee prostheses.

OBJECTIVE: To improve the design of the knee prosthesis, a new technique to design the tibial baseplate of total knee prostheses was developed. METHODS: One senior surgeon operated on 79 osteoarthrosis patients by using PCA total knee prostheses for total knee replacement. Four dimensions were measured intraoperatively and compared, including the anterioposterior length and the mediolateral width of the resected tibia plateau and implant. The data of anterioposterior length and the mediolateral width of resected surfaces of the tibial plateau of the 79 patients were plotted in a coordinate system. This coordinate system was formed with the mediolateral width as the x-axis and anterioposterior length as the y-axis. A circle, 5 mm in diameter, was used as the maximum coverage criterion. Five contemporary products and a new design product were used to screen the data to see how many patients would fall within the criteria. From the results of the screened data, we calculated the coverage percentage of the patients. RESULTS: The ratio of the anterioposterior length to the mediolateral width of the resected surfaces of the tibial plateau was greater than that of the ratio of the PCA prostheses (P < 0.05). The results showed that no single product on the market had the patients meet over 70% of the criterion. A different ratio of the anterioposterior length to the mediolateral width was designed to achieve 90% coverage of the patients that met the criterion. DISCUSSION: One possible explanation for the discrepancy between resected surfaces and implants is that the osteoarthrosis patients developed knee deformities that changed the surface of the tibial plateau and thus altered the knee dimensions. Since the total knee prostheses were used on osteoarthrosis patients, the dimensions of the resected tibial surfaces of osteoarthrosis patients should be considered in the design of the tibial baseplate of total knee prostheses.

Aged↗
PubMed1999

The influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing.

OBJECTIVE: To investigate the influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing. DESIGN: An experimental set-up was used to measure the total contact areas of the tibiofemoral joint of the prostheses subjected to a compressive load, and the malalignment situations were simulated. BACKGROUND: The contact alignment of the femoral component related to the tibial component in the literature was not described clearly and the effect of malalignment on the testing method has not been reported well. METHODS: Three commercial knee prostheses (Omnifit, Genesis, and AMK) were used for testing under a compression load (3000 N) at flexion 0 degrees and 10 degrees. After aligning the normal contact alignment, the simulated malalignment was done to evaluate the influence on the total contact areas in these conditions relative to the normal contact alignment. The simulated malalignment includes the medial-lateral translation (0.5 and 1 mm), anterior-posterior translation (2 and 4 mm) and internal-external rotation (1 degrees, 3 degrees and 5 degrees ) of the femoral component relative to the tibial component. RESULTS: The ratios of total contact areas of malalignment relative to normal contact alignment ranged from 1.06 to 0.93 in medial-lateral malalignment in these three prostheses. In anterior-posterior malalignment, the ratios ranged from 0.69 to 0.79 in Omnifit, 0.93-0. 96 in Genesis and 0.96-1.04 in AMK. In internal-external malrotation, the ratios ranged from 0.90 to 1.03 in these prostheses. CONCLUSIONS: This study proposes that contact alignment would affect the contact characteristics, especially in anterior-posterior alignment when high conformity knee prosthesis is tested. The contact alignment must be standardized in the procedure in in vitro biomechanical testing, which will be more objective to evaluate the contact characteristics of different knee prostheses. RELEVANCE: This study revealed the importance of contact alignment of the tibiofemoral joint of the prosthesis in in vitro biomechanical testing. Many published reports of the biomechanical evaluations on different designs of knee prostheses would show different results due to contact alignment. Furthermore, this study indicates that the ideal contact characteristics of the tibiofemoral joint in original design will be changed when the prosthesis under the malalignment condition which was caused by surgery technique or soft tissues imbalance.

Biomechanical Phenomena↗
PubMed1999

Failure of the all-polyethylene patellar component after total knee arthroplasty.

From 1991 to 1996, 953 cases of porous-coated anatomic modular knee prostheses with all-polyethylene patellar components were implanted. Among them, 4 cases had breakage of the patellar component at the peg-button interfaces. One had loosening of the patellar component by cutting out the patellar bony bed. Heavy body weight, weakness of the pegs of the all-polyethylene patellar component, and osteonecrosis of the patella were conceived as the causes of failure.

Aged↗
PubMed1999

Fracture of the femoral component associated with polyethylene wear and osteolysis after total knee arthroplasty.

Fracture of the femoral component associated with polyethylene wear and osteolysis after total knee arthroplasty (TKA) has not been well reported before. A 63-year-old man with osteoarthritis of the right knee underwent TKA with a New Jersey LCS Knee, with cementing on the tibia and patella but not on the femoral component. After 42 months, in addition to wearing of polyethylene of the tibia and patella, severe osteonecrosis of the medial femoral condyle was noted. Osteonecrosis caused loss of osseous support of the medial flange of the femoral component, and the bone ingrowth of the central and lateral flange to the distal femur was so good that it overcame the yield stress of the metal of the femoral component and caused fracture of the femoral component. The osteolytic area was filled with autogenous iliac bone, and a new femoral component was inserted and cemented. The patient's condition became satisfactory with relief of pain. Although uncommon, fracture of the femoral component does occur associated with polyethylene wear and osteolysis.

Arthroplasty, Replacement, Knee↗
PubMed1999

Hydrolysis of naptalam and structurally related amides: inhibition by dissolved metal ions and metal (hydr)oxide surfaces.

In metal ion-free solutions, the secondary amide naptalam hydrolyzes more rapidly as the pH is decreased; intramolecular nucleophilic attack by a carboxylate side group is very likely involved. Millimolar levels of dissolved Cu(II) and Zn(II) inhibit hydrolysis between pH 3.6 and pH 6.5. Metal ion-naptalam complex formation is important since addition of the competitive ligand citrate lessens the inhibitory effect. The metal (hydr)oxide surfaces Al(2)O(3) and FeOOH inhibit naptalam hydrolysis to a lesser degree; inhibition is proportional to the extent of naptalam adsorbed. Secondary amides (propanil, salicylanilide, and N-1-naphthylacetamide) and tertiary amides (N-methyl-N-1-naphthylacetamide, furalaxyl, and N, N-diethylsalicylamide) that lack carboxylate side groups do not hydrolyze within 45 days of reaction, even when millimolar Cu(II) concentrations are present. Tertiary amides possessing carboxylate side groups (N,N-diethyl-3,6-difluorophthalamic acid and N, N-dimethylsuccinamic acid) do hydrolyze but are insensitive to the presence or absence of Cu(II). The inhibitory effect is believed to occur via metal coordination of (1) the carbonyl group of naptalam, which induces deprotonation of the amide group and makes the substrate less reactive toward nucleophilic attack; (2) the free carboxylate group of naptalam, which blocks intramolecular nucleophilic attack; or (3) a combination of the two.

Agrochemicals↗
PubMed1999

The mouse Rhl1 and Rhag genes: sequence, organization, expression, and chromosomal mapping.

To seek an alternative model for studies of the Rh protein complex, we isolated by homology cloning and characterized the mouse Rhced and Rhag genes, which are homologous to the human RH and RHAG genes, respectively. Rhced encodes a glycoprotein of 418 amino acids which occurs as a composite of human RhD and RhCE with 60% identity and 74% similarity. Rhag encodes a glycoprotein of 438 amino acids that shares 79% identity and 87% similarity to human Rh50. However, Rhag has an elongated C terminus and four N-glycosylation sites clustered on exoloop 1. Hydropathy plots suggest that Rhl1 and Rhag each span the lipid bilayer 12 times, with N and C termini facing the cytoplasm. Rhced and Rhag are both specified by 10 exons and bear a similar exon/intron structure, but their major transcription start sites are mapped at -17A and -27A. Northern analysis revealed coexpression of Rhced and Rhag from 11-day embryos throughout adult life in erythroid tissues. Southern blotting and linkage analysis showed that Rhced and Rhag are single-copy genes localized to chromosomes 4 and 17, respectively; they are paralogous to one another but orthologous to human RH and RHAG. The results together predate the occurrence and signify a conserved function of the erythroid-specific Rh membrane structures.

3T3 Cells↗