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Biomedical subjects

W B Chen

Publications and source records attributed to W B Chen.

At least 19 recordsLinked to original sources
PubMed2003

Recycling and reuse of wastewater from a new-developed community using sand filtration, ultrafiltration, and ozonation.

In this study, the pilot apparatus combined with sand filtration, ozonation and ultrafiltration was established. Wastewater from the secondary treatment effluent in the new-developed community was taken as the sample for looking into the feasibility of domestic wastewater reuse and recycling. The test results by sand filtration, sand filtration/ultrafiltration, sand filtration/ozonation, and sand filtration/ultrafiltration/ozonation were compared for looking for appropriate treatment processes applied in the domestic wastewater reuse and recycling. Finally, cost analysis was carried out and sand filtration/ozonation process was suggested to be one of the best processes. The total cost is about 0.1-0.32 USD dollars per cubic meter of produced water by considering the capital and operation cost for five years in the small domestic wastewater treatment plant (50-750 CMD).

Conservation of Natural Resources↗
PubMed2003

Effects of the preparation methods of hydroxypropyl methylcellulose/polyacrylic acid blended films on drug release.

Hydroxypropyl methylcellulose (HPMC)/polyacrylic acid (PAA) blended films were prepared under different conditions (i.e. temperature, solvent, and cross-linking agent). The effects of hydrogen-bonding interactions or a chemical reaction between the two-component polymers in the blended films on drug release were studied. Two model drugs were used for comparison: a water-soluble drug, dl-propranolol hydrochloride, and a lipophilic drug, ketoprofen. The H-bonding interaction of HPMC/PAA was found to be stronger in the blended films prepared from H2O than that from H2O/EtOH. However, the H-bonding effect between HPMC and PAA on drug release is indistinct. Chemical esterification of the carboxylic acid groups of PAA with the hydroxyl groups of HPMC was proposed from the solid-state NMR, ESCA, and FTIR studies when the blended films were dried at 110 degrees C. This chemical reaction also resulted in insolubilization of the blended films.

Acrylic Resins↗
PubMed2002

Synthesis and properties of a naproxen polymeric prodrug.

A water-soluble polymeric prodrug containing a naproxen moiety was synthesized. The carboxylic groups of naproxen were condensed with the hydroxyl groups of 2-hydroxyethyl methacrylate (HEMA) to produce a drug-linked monomer, denoted HN. The polymeric prodrug was prepared by copolymerization of HN with methacrylic acid. The molar percentage of HN in the polymeric prodrug was 26 mol%, as determined by 1H NMR. To investigate the pertinence of this polymeric prodrug, the hydrolysis was studied in-vitro with or without esterase or lipase. The kinetics of enzymatic catalysis was calculated from a Lineweaver-Burk plot. The anti-inflammatory activity was evaluated using the carrageenan-induced oedema test. The polymeric prodrug released a major fraction of the free naproxen and a significant fraction of the hydroxyethyl ester derived-naproxen. The maximum hydrolysis rate Vmax, and the Michaelis constant Km were calculated to be 2.16 x 10(-5) equiv. mol L-1 min-1 and 5.11 x 10(-2) equiv. mol L-1. The maximum anti-inflammatory inhibition of free naproxen appeared at 2 h and quickly decreased thereafter. In contrast, the polymeric prodrug showed a maximum at around 2-3 h and then slowly decreased. This indicates that the polymeric prodrug displays greater potency than free naproxen in the inhibition of acute inflammatory processes over long periods.

Animals↗
PubMed2002

Ozonation of domestic secondary effluent for recycling and reuse--a pilot plant study.

In this study, a pilot plant combined ozonation with sand filtration is established. Wastewater from the secondary effluent was taken as the sample for looking into the feasibility of domestic wastewater recovery and recycling. At the beginning, a series of hydraulic analysis and ozone transfer tests was conducted in the bubble column reactor. From these tests, it was found that when the gas flow is controlled to within 0.2 to approximately 1.0 L/min and liquid flow within 0.5 to approximately 2.5 L/min, using series connected mixing tank model for our calculation, the result J (CSTR) is 1 to approximately 2. From the ozone transfer test it is known that the smaller the gas flow, the better the transfer rate, and the same pattern occurs on ozone gas concentration. After sand filtration and ozone treatment, the G/L ratio within the ozone column reactor can be maintained within 0.2 to approximately 0.4 and the ozone dosage within 8 to approximately 12 mg/L. The removal rate for coliform bacillus, BOD, turbidity and color is 99.96%, 62.2%, 89.6% and 67% respectively. After ozonation treatment, coliform bacillus content can be controlled under 10 CFU/mL, BOD under 10 mg/L, turbidity within 2.0 to approximately 2.5 (NTU), and color within 10.3 to approximately 13.7 degree. The recycled water is almost colorless and odorless, and is capable of reaching the reference standard for recycled water.

Conservation of Natural Resources↗
PubMed2001

Study of cytochrome P4502E1 mRNA level of mononuclear cells in patients with alcoholic liver disease.

BACKGROUND: Cytochrome P-4502E1 (CYP2E1) is an important enzyme because of its unique ability to convert many substrates to cytotoxins. The increased production of reactive intermediates by elevated enzyme concentrations leads to various pathological conditions. Therefore, it is important to detect induced CYP2E1 levels in alcoholic individuals to avoid xenobiotic-promoted liver injury. In the present investigation, we detected CYP2E1 mRNA levels of mononuclear cells obtained from 10 ml of blood by using competitive polymerase chain reaction (PCR) method. METHODS: Mononuclear cells were obtained from healthy individuals who did and did not drink habitually and patients with alcoholic liver disease (ALD). Complementary DNA synthesis was performed with RNA obtained from mononuclear cells by reverse transcription-PCR. Competitive PCR of CYP2E1 was performed with the sense (5'-CTGCAACGTCATA-GCCGACA-3') and antisense (5'-TCCATTTCCACGAGCAGGCA-3') primer and competitor DNA. Competitive PCR of beta-actin also was performed. Electrophoresis was scanned, and each band was digitized. The concentration of CYP2E1 and beta-actin mRNA was calculated from the ratio of competitor DNA. RESULTS: In healthy individuals who did and did not drink habitually, CYP2E1 mRNA levels were 103.3 copies/microl RNA and 101.7 copies/microl RNA, respectively. In actively drinking patients with ALD, CYP2E1 mRNA levels were 103.5 copies/microl RNA, but those levels decreased to 101.7 copies/microl RNA after 4 days of abstinence. No significant difference was observed in CYP2E1 mRNA levels between alcoholic fibrosis and cirrhosis. As control, we measured beta-actin mRNA levels in mononuclear cells in all samples. The mean value of beta-actin mRNA was 104.3 copies/microl RNA in all cases, which included patients with ALD. CONCLUSIONS: The results demonstrated that it is possible to measure the CYP2E1 mRNA levels of mononuclear cells in a 10 ml blood sample. The CYP2E1 mRNA level in mononuclear cells increases during drinking and decreases in abstinence for a short period of 3 to 4 days. It is concluded that CYP2E1 mRNA level may be used as an effective marker for alcoholic intake.

Actins↗
PubMed2001

[Tetrandrine loaded sustained-release microcapsules for lung targeting].

AIM: To prepare lung targeted tetrandrine (TET) loaded sustained-release drug delivery system by microencapsulation, decrease the toxicity and enhance the therapeutic function of anti-pulmonary hypertension of TET. METHODS: Albumin microcapsules were produced by spray drying-thermal denaturation, a new technique. Some characterization of the prepared microcapsules was evaluated. Distribution of the microcapsules and their anti-pulmonary hypertension effect in vivo were investigated. RESULTS: The spherical microcapsules showed a drug loading of 37.88%. Compared to the original drug, the rate of TET released from the positively charged microcapsules in vitro was significantly decreased and fitted well by Higuchi equation. The TET concentrations in mouse lungs of TET microcapsules were significantly higher than those of TET injection, and the mean retained time of TET in lungs was prolonged from 157.1 h to 223.6 h after microencapsulation. The in vitro--in vivo correlation was established and confirmed (P < 0.001). CONCLUSION: The new spray drying-thermal denaturation method allows the preparation of drug loaded albumin microcapsules with desired results. The prepared microcapsules were found to have the potential function of delivering TET to pulmonary artery via i.v., with low toxicity and high efficacy.

Alkaloids↗
PubMed2000

Formation of 20-hydroxyeicosatetraenoic acid, a vasoactive and natriuretic eicosanoid, in human kidney. Role of Cyp4F2 and Cyp4A11.

20-hydroxyeicosatetraenoic acid (20-HETE), an omega-hydroxylated arachidonic acid (AA) metabolite, elicits specific effects on kidney vascular and tubular function that, in turn, influence blood pressure control. The human kidney's capacity to convert AA to 20-HETE is unclear, however, as is the underlying P450 catalyst. Microsomes from human kidney cortex were found to convert AA to a single major product, namely 20-HETE, but failed to catalyze AA epoxygenation and midchain hydroxylation. Despite the monophasic nature of renal AA omega-hydroxylation kinetics, immunochemical studies revealed participation of two P450s, CYP4F2 and CYP4A11, since antibodies to these enzymes inhibited 20-HETE formation by 65. 9 +/- 17 and 32.5 +/- 14%, respectively. Western blotting confirmed abundant expression of these CYP4 proteins in human kidney and revealed that other AA-oxidizing P450s, including CYP2C8, CYP2C9, and CYP2E1, were not expressed. Immunocytochemistry showed CYP4F2 and CYP4A11 expression in only the S2 and S3 segments of proximal tubules in cortex and outer medulla. Our results demonstrate that CYP4F2 and CYP4A11 underlie conversion of AA to 20-HETE, a natriuretic and vasoactive eicosanoid, in human kidney. Considering their proximal tubular localization, these P450 enzymes may partake in pivotal renal functions, including the regulation of salt and water balance, and arterial blood pressure itself.

Antibodies↗
PubMed2000

Isolation, purification, and characterization of a killer protein from Schwanniomyces occidentalis.

The yeast Schwanniomyces occidentalis produces a killer toxin lethal to sensitive strains of Saccharomyces cerevisiae. Killer activity is lost after pepsin and papain treatment, suggesting that the toxin is a protein. We purified the killer protein and found that it was composed of two subunits with molecular masses of approximately 7.4 and 4.9 kDa, respectively, but was not detectable with periodic acid-Schiff staining. A BLAST search revealed that residues 3 to 14 of the 4.9-kDa subunit had 75% identity and 83% similarity with killer toxin K2 from S. cerevisiae at positions 271 to 283. Maximum killer activity was between pH 4.2 and 4.8. The protein was stable between pH 2.0 and 5.0 and inactivated at temperatures above 40 degrees C. The killer protein was chromosomally encoded. Mannan, but not beta-glucan or laminarin, prevented sensitive yeast cells from being killed by the killer protein, suggesting that mannan may bind to the killer protein. Identification and characterization of a killer strain of S. occidentalis may help reduce the risk of contamination by undesirable yeast strains during commercial fermentations.

Amino Acid Sequence↗
PubMed1997

Intravenous pretreatment of hypertonic saline can prevent systemic hypotension induced by spinal anesthesia.

BACKGROUND: Hypertonic saline improves organ perfusion and patient survival during hemorrhagic shock because it expands plasma volume and increases tissue oxygenation. Its beneficial results have been reported in patients suffering from hypotension during spinal anesthesia. The purpose of this study was to compare the influence between prehydration with 3% hypertonic saline and with isotonic lactated Ringer's solution on the hemodynamic changes and serum electrolyte concentrations in patients undergoing spinal anesthesia. METHODS: Sixty ASA class I patients scheduled for herniorrhapy under spinal anesthesia were assigned randomly into two groups. Group 1 = patients were prehydrated with isotonic lactated Ringer's solution at 7 mg/kg (n = 30); Group 2 = patients were given prehydration with 3% hypertonic saline at 7 ml/kg (n = 30). Following prehydration, arterial blood pressure and heart rate were recorded and serum electrolyte concentrations were measured. RESULTS: The incidence of hypotension was 17/30 (57%) in the isotonic lactated Ringer's solution group as against 7/30 (23%) in the hypertonic saline group (p < 0.05). There was no significant difference between two groups in relation to the level of anesthesia or maximal heart rate, and electrolyte imbalance did not occur in either group. CONCLUSIONS: Prior to spinal anesthesia, hydration with small amount of hypertonic saline is effective to minimize hypotension associated with spinal anesthesia. If so administered it would not increase bodily sodium load and unlike isotonic crystalloid solution it dose not cause accumulation of water in the body on equipollent basis.

Adult↗
PubMed1997

Clinical significance of hepatitis GB virus C infection in alcoholic liver disease.

Recently, hepatitis GB virus C (HGBV-C) has been recovered from patients with non-A-E hepatitis. However, it has been unclear whether HGBV-C may be related to the development of alcoholic liver disease (ALD) or not. In this study, we determined HGBV-C RNA in sera from alcoholic patients without markers for hepatitis C and B viruses to evaluate the role of HGBV-C in ALD. Serum samples were obtained from 68 patients with ALD and 40 nonalcoholic patients with chronic type C liver disease. HGBV-C RNA was detected in only 3 of 68 (4.4%) patients with ALD, in 2 of 27 patients with hepatic fibrosis, and in 1 of 5 patients with chronic hepatitis. There was no HGBV-C RNA in sera from patients with fatty liver, alcoholic hepatitis, or cirrhosis. Serum levels of AST, ALT, and gamma-glutamyltranspeptidase in alcoholic patients with, as well as without, HGBV-C RNA decreased to normal levels after abstinence. In addition, an inflammatory change was not observed in liver biopsy specimens obtained from two HGBV-C-positive patients with alcoholic hepatic fibrosis. Our results clearly suggest that the prevalence of HGBV-C infection in patients with ALD is rare and that HGBV-C may not play an important role in the development of liver disease in alcoholics.

Alcohol Drinking↗
PubMed1993

[Clinical application of the forced inspiratory volume-time curve. A preliminary study].

The forced inspiratory volume-time curve in 25 health subjects with normal ventilation function and 25 patients with COPD were determined, and MMIF, FIV were calculated from the curves. The PImax was measured in the same 50 subjects by modified Blac method sequentially. A close relationship between MMIF, FIV and PImax was found. This result indicated that MMIF and FIV could be indeed for evaluation of strength of respiratory, muscles. Additional observations of MMIF, FIV and PImax in 50 patients with COPD before and after inotropic drugs, aminophylline and CNB, further proved the validity of MMIF and FIV.

Aged↗
PubMed1992

[The diagnostic value of transbronchial needle aspiration in patients with extrabronchial bronchogenic carcinoma].

Tissue pathologic and cytologic examination of 47 cases with suggestive extrabronchial bronchogenic carcinoma using the four technics of transbronchial needle aspiration (TBNA), bronchial biopsy, brushing and washing through the fiberoptic bronchoscopy were reported. For any one case, any one or more of the above said technic showed positivity will be regarded as positive case. The results showed that the total positive rate was 82.9%. The diagnostic rate of using TBNA alone was 68.1% that of bronchial biopsy 63.8% and bronchial brushing 70.2% (P > 0.05), but obviously higher than the bronchial washing (34.0%) (P < 0.05). Thus the deficiency of any one above said technic will be complemented by one of the other technics. The results also showed that TBNA is especially suitable for use in the squamous and small cell types of lung cancer. Complications of pneumothorax or bleeding were not found with the TBNA technic. We, therefore, recognize that the TBNA is one of a high positive rate, easily performed and with few complications diagnostic technic for extrabronchial bronchogenic carcinoma, and it should be recommended for clinical application.

Adult↗
PubMed1992

[The diagnosis of smear negative pulmonary tuberculosis in superior segment of lower lobe].

20 cases of tuberculosis in the superior segment of the lower lobe of the lung were misdiagnosed as lung cancer, pneumonia, bronchiectasis and inflammatory pseudoneoplasm were reported. The final diagnosis were confirmed by fiberoptic bronchoscopy (FOB). The causes of the misdiagnoses were: (1) the hilar mass shadow found on the PA chest film, mistaken for central type lung cancer; (2) the mass shadow found on the lateral chest film, mistaken for peripheral lung cancer; (3) the patients with fever, cough and expectoration accompanied by exudative infiltrative shadow, mistaken for pneumonia; (4) patients with recurrent attacks of hemoptysis but the lesions overshadowed by the spinal column on the lateral chest film were misdiagnosed as bronchiectasis. The author suggested PA and lateral chest films taken simultaneously were needed. The special points, to which should be pay attention during reading the films were listed and noted. FOB examination including TBLB, brushing and BALF for pathologic and AFB determination could be of help to confirm the diagnosis.

Adolescent↗
PubMed1991

[Aggressive fibrous histiocytoma of bone--report of two cases].

Three osseous tumors multicentrically arising in the radius, ulna, and metacarpal bones of a 10-year-old girl and another in the femur of a 75-year-old man are reported. These lesions were designated as aggressive fibrous histiocytoma because of the benign cytological appearance with aggressive roentgenographic findings. These tumors were composed mainly of spindle cells tightly packed in a storiform pattern. Clear histiocytes and multinuclear giant tumor cells were occasionally seen. Variable amounts of collagen fiber were found. Both patients have been followed for 32 and 21 months respectively without evidence of local recurrence or distant metastasis.

Aged↗