Biomedical subjects

Yang Wang

Publications and source records attributed to Yang Wang.

At least 235 records · Page 13Linked to original sources

PubMed2002

Uncertainties and novel prospects in the study of the soil carbon dynamics.

Establishment of the Kyoto Protocol has resulted in an effort to look towards living biomass and soils for carbon sequestration. In order for carbon credits to be meaningful, sustained carbon sequestration for decades or longer is required. It has been speculated that improved land management could result in sequestration of a substantial amount of carbon in soils within several decades and therefore can be an important option in reducing atmospheric CO2 concentration. However, evaluation of soil carbon sources and sinks is difficult because the dynamics of soil carbon storage and release is complex and still not well understood. There has been rapid development of quantitative techniques over the past two decades for measuring the component fluxes of the global carbon cycle and for studying the soil carbon cycle. Most significant development in the soil carbon cycle study is the application of accelerator mass spectrometry (AMS) in radiocarbon measurements. This has made it possible to unravel rates of carbon cycling in soils, by studying natural levels of radiocarbon in soil organic matter and soil CO2. Despite the advances in the study of the soil carbon cycle in the recent decades, tremendous uncertainties exist in the sizes and turnover times of soil carbon pools. The uncertainties result from lack of standard methods and incomplete understanding of soil organic carbon dynamics, compounded by natural variability in soil carbon and carbon isotopic content even within the same ecosystem. Many fundamental questions concerning the dynamics of the soil carbon cycle have yet to be answered. This paper reviews and synthesizes the isotopic approaches to the study of the soil carbon cycle. We will focus on uncertainties and limitations associated with these approaches and point out areas where more research is needed to improve our understanding of this important component of the global carbon cycle.

Carbon↗

PubMed2002

Transfection of tubule cells with Fas ligand causes leukocyte apoptosis.

BACKGROUND: Since the Fas/Fas Ligand (FasL) interaction is recognized as a major pathway of apoptosis in immune cells, we hypothesized that selective expression of FasL by tubular cells (TC) may promote the resolution of interstitial inflammation by inducing apoptosis of infiltrating immune cells. In this study, the effect of FasL transfection of rat TC on apoptosis of leukocytes was examined. METHODS: Rat tubule cells (NRK52E) were transfected with plasmids constructed using human and rat FasL (hFasL and rFasL). The propensity of activated, transfected TC to undergo apoptosis was examined. Similarly, the effects of FasL transfection on apoptosis of Jurkat cells and activated leukocytes were assessed directly following co-culture for 12 hours and in a cell insert system intended to assess the effects of soluble FasL. Fas and FasL expression was assessed by flow cytometry and apoptosis was examined using Annexin V staining and the TUNEL method. RESULTS: Expression of FasL in TC was increased after FasL transfection. Transfected TC showed no detectable increase in apoptosis following lipopolysaccharide (LPS) or tumor necrosis factor-alpha (TNF-alpha) activation. Jurkat cell apoptosis was increased ninefold and eightfold after co-culture with TC transfected with hFasL and rFasL, respectively (67.0 +/- 12.1% and 60.1 +/- 8.8% vs. 6.7 +/- 1.8% with un-transfected TC, P < 0.01). Similarly, apoptosis of activated leukocytes was increased fourfold by co-culture (26.8 +/- 4.9% vs. 6.7 +/- 2.0% with untransfected TC, P < 0.01). Leukocyte apoptosis also was increased in an insert culture system (18.2 +/- 4.4% vs. 5.8 +/- 2.3% with un- transfected TC, P < 0.01). No increase of TC apoptosis was detected in any of the co-culture experiments. CONCLUSION: Enhanced expression of FasL by TC is capable of inducing apoptosis of activated leukocytes, without evidence for increased susceptibility to apoptosis of the transfected cells themselves. This suggests a potential role for this approach in the limitation and resolution of renal tubulointerstitial inflammation.

Animals↗

PubMed2002

Among substituted 9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4,5,8-tetraones, the lead antitumor triptycene bisquinone TT24 blocks nucleoside transport, induces apoptotic DNA fragmentation and decreases the viability of L1210 leukemic cells in the nanomolar range of daunorubicin in vitro.

In contrast to their inactive parent compound triptycene (code name TT0), several new synthetic analogs (TT code number) have antileukemic activities and remain effective in daunorubicin (DAU)-resistant tumor sublines in vitro. Among variously substituted 9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4,5,8-tetraones, a total of six lead antitumor compounds have been identified, and their code names are TT2, TT13, TT16, TT19, TT21 and TT24. These active antitumor triptych structures have bisquinone functionality, and various bromo, methoxy, methylamino and/or dimethylamino substitutions with or without longer alkyl chains on the amino function. Like the anthracycline quinone antibiotic DAU, these triptycene (TT) bisquinones also inhibit DNA synthesis and induce DNA cleavage in relation with their cytotoxic activities, but have the additional advantage of blocking the cellular transport of purine and pyrimidine nucleosides, an effect which DAU cannot do. As demonstrated by intact chromatin precipitation and agarose gel electrophoresis, the ability of TT bisquinones and DAU to induce DNA fragmentation is biphasic with a peak that shifts to lower concentrations with increasing times of drug exposure. The most effective lead antitumor compound, TT24, induces DNA cleavage in the same concentration-dependent manner as DAU at 24 h (similar peak in response to 1.6 microM) and is nearly equipotent to DAU against L1210 tumor cell viability at day 4 (IC50 values of TT24 and DAU: 48 and 25 nM, respectively). The mechanism by which TT24 induces DNA fragmentation is inhibited by actinomycin D, cycloheximide, benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone, benzyloxycarbonyl-Ile-Glu-Thr-Asp-fluoromethyl ketone, N-tosyl-L-phenylalanine chloromethyl ketone and ZnSO4, suggesting that TT bisquinones trigger apoptosis by caspase and endonuclease activation. Since TT24 is cytotoxic in the nanomolar range of DAU, but might have a more versatile mechanism of action than DAU in wild-type and multidrug-resistant tumor cells, this new class of DNA-damaging quinone antitumor drugs inhibiting nucleoside transport might be valuable to develop new means of polychemotherapy.

Animals↗

PubMed2002

All-trans retinoic acid as a single agent induces complete remission in a patient with acute leukemia of M2a subtype.

OBJECTIVE: To present a special case with the karyotype and molecular marker of acute myeloid leukemia (AML)-M2 who was induced to complete remission by all-trans retinoic acid (ATRA) alone. METHODS: A recently hospitalized young female patient with acute leukemia was initially diagnosed as M3 subtype based on morphological French-American-British (FAB) classification. Karyotype analysis using standard G and R banding techniques and RT-PCR were applied to further define the diagnosis. After primarily cultured bone marrow cells from the iliac aspiration were tested for in vitro induced differentiation, the patient was treated with oral all-trans retinoic acid alone, 60 mg per day until complete remission was achieved. Peripheral blood and bone marrow changes were monitored over the whole treatment course. RESULTS: The characteristic chromosomal aberration for M3, the t(15;17) reciprocal translocation, was not found while a t(8;21) translocation was verified. Furthermore, an amplified product of the AML-1/ETO fusion gene instead of the PML/RAR alpha fusion gene was detected by RT-PCR and the diagnosis was corrected from M3 to M2. Primary cultured bone marrow cells can be fully induced to terminal differentiation after 4 days exposure to ATRA. A hematological complete remission was achieved after 40 days treatment with ATRA as a single therapeutic agent, suggesting an alternative pathway mediating ATRA-induced myeloid differentiation. CONCLUSION: A leukemia patient with a subtype other than M3, such as M2 in this case, may also be induced to complete remission by the mechanism of ATRA-induced terminal differentiation. This implies that there may be a pathway other than PML/RAR alpha fusion gene product which mediates ATRA-induced myeloid maturation in leukemia cells.

Adolescent↗

PubMed2002

[Late course accelerated hyper-fractionated radiotherapy of upper and middle thoracic esophageal T2N0M0 carcinoma].

OBJECTIVE: To analyse the result of late course accelerated hyper-fractionated radiotherapy (LCAHFR) of upper and middle thoracic segment esophageal T2N0M0 carcinoma. METHODS: Fifty-three patients with squamous cell esophageal T2N0M0 carcinoma in the upper and middle segment were treated by LCAHFR from August 1994 to January 2000. The design of the radiation fields were based on CT and barium examination. All patients were treated with the conventional fractionated radiotherapy during the first two-thirds of the treatment to a dose about 41.4 Gy/23 F/4 to 5 weeks. This was followed by accelerated hyper-fractionated irradiation using reduced fields, twice daily at 1.5 Gy per fraction to a dose about 27 Gy/18 d. Thus, the total dose was 67-70 Gy/40-43 F/40-49 d. RESULTS: The 1-, 2- and 5-year actuarial survival rates were 89.9%, 66.8% and 51.2%, respectively. The 1-, 2- and 5-year local control rates were 92.1%, 87.1% and 87.1%. Of the 17 patients who died, 5 died of local failure (29.4%), 9 (52.9%) of distant metastasis, 5 (29.4%) of lymph metastasis and 1 (5.9%) of bleeding from the esophagus. The Cox multivariate model showed that the site of lesion was the only prognostic factor, with upper better than the middle segment. CONCLUSION: Late course accelerated hyper fractionated radiotherapy is one of the best radiation treatment regimen for early esophageal carcinoma in the upper and middle thoracic segment.

Aged↗

PubMed2002

[Construction and tumorigenic study on a novel fusion gene AML1-MTG16].

OBJECTIVE: To test whether splicing overlapping extension(SOE) method can be a tool for obtaining rare fusion gene's transcripts and to study the tumorigenic capacity of a novel fusion gene AML1-MTG16. METHODS: SOE method was used to obtain AML1- MTG16 fusion gene's transcripts. MTG16, AML1-MTG16 and AML1-MTG16 without III,VI conserved domains of MTG16 segment were inserted into pEGFP- C1,pDsRed-N1 vector respectively,then transfected NIH3T3 cell line by lipofection. Forty-eight hours later, the transfected cells were examined by laser-scanning confocal microscopy. Stable transfected cells were obtained by G418 500ug/ul selection for one month. Growth curve, soft agar colonies formation tumorigenesis in nude mice were done to compare the difference between stable transfected cells. RESULTS: Recombined AML1-MTG16 by SOE contained its CDS. NIH3T3 expressing AML1-MTG16 had a faster proliferation in medium, colony growth in soft agar. AML1-MTG16 expression cells also induced tumors formation following injection into nude mouse. MTG16,AML1-MTG16 and AML1-MTG16 without III,VI conserved domains of MTG16 were colocalized in the nucleus of cotransfected NIH3T3 cells under the examination of laser-scanning confocal microscope. CONCLUSION: SOE is an effective method to get rare fusion gene's transcripts. AML1-MTG16 plays an important role in leukemogenesis. MTG16 may also have a carcinogenic property within the AML1-MTG16 fusion gene. Carcinogenic property of AML1-MTG16 is restricted to its localization in the nuclear matrix. N terminal of MTG16 may play an important part in the carcinogenic activity of AML1-MTG16.

3T3 Cells↗

PubMed2002

[Fat particle injection auto-transplantation a 10-year review].

OBJECTIVE: To summarize clinical experiences in fat particle injection auto-transplantation during the past ten years. METHODS: Retrospective analysis of 334 cases of fat particle injection auto-transplantation was done, and we suggested the correct method of liposuction and fat injection. RESULTS: In this series, one patient (0.29%) had a complication, thirty one patients (9.38%) had lower survival of autogenous fat-transplantation. CONCLUSION: In order to improve the results of fat-grafting, we must adopt the correct method of liposuction and follow the right rules.

Adipocytes↗

PubMed2002

[The relationship between arterial blood oxygen pressure and the changes in blood biochemical indices after partial liquid ventilation in canine inhalation injury].

OBJECTIVE: To explore the therapeutic effects of partial liquid ventilation on canine inhalation injury. METHODS: Mongrel dogs were inflicted with steam inhalation injury and were employed as the model. Partial liquid ventilation was accomplished by slow instillation of into the lungs. The changes in blood superoxide dismutase (SOD), malondialdehyde (MDA), nitric oxide (NO) and arterial oxygen pressure (PaO(2)) were determined. RESULTS: The blood levels of MDA and NO at 2 postburn hours (PBHs) increased obviously but those of SOD and PaO(2) decreased significantly when compared with those before injury (P < 0.05). The blood levels of SOD, MDA, NO and PaO(2) recovered to near preinjury levels after partial liquid ventilation. CONCLUSION: Partial liquid ventilation might be helpful in the management of inhalation injury by raising blood oxygen pressure, antagonizing lipid peroxidation and reducing the in vivo NO production.

Animals↗

PubMed2002

[An experimental study on the cograft of auto-microskin and allo-dermal matrix].

OBJECTIVE: To explore the promoting effects of cograft of auto-microskin and allo-dermal matrix on burn wound healing. METHODS: Forty-six patches of full skin loss wounds were made in the backs of 6 small white swines. Auto-microskin and meshed acellular allo-dermal matrix were simultaneously prepared. The 46 wounds were averagely divided into test (T) and control (C) groups. The wounds in T group were covered with auto-microskin and allo-dermal matrix (1:4) and split-thick allo-porcine skin. While the wounds in C group were grafted with autoskin and allo-dermal matrix. RESULTS: The skin survival rate exhibited no difference between C and T groups (P > 0.05). There was similar histological exhibition in the two groups after skin grafting. The structure of collagen fibres appeared integrated, clear with regular arrangement and steady diameter at 8 - 20 post-operative weeks. Simultaneously, it was revealed by histological examination that normal vascular structure could be identified in the grafted skin and that inflammatory reaction ameliorated gradually and that epithelium combined well with dermis. It was also found that the epidermal papillar across the basement membrane fixed well to allo-dermis. The skin appeared smooth, elastic and functioned well at 5 months after skin grafting. CONCLUSION: The grafted skin survived well after the cograft of auto-microskin and allo-dermal matrix, which might be ideal covering material for the major deep burn wound healing.

Animals↗

PubMed2002

[The influence of lanthanum chloride on the TNFalpha expression of murine peritoneal macrophages stimulated by lipopolysaccharide].

OBJECTIVE: To explore the influence of lanthanum chloride on the TNFalpha expression of murine peritoneal macrophages stimulated by lipopolysaccharide (LPS). METHODS: Murine peritoneal macrophages (Mphi) were isolated, cultured and then stimulated by LPS. The influence of lanthanum chloride on the TNFalpha secretion and TNFalphamRNA expression of murine Mphi stimulated by LPS was determined by ELISA method and SYBR green fluorescence quantitative RT-PCR. Forty BALB/C mice were randomly divided into two groups and were treated by lethal dose of LPS and lanthanum chloride processed LPS, respectively. The mortality within 7 days was observed. RESULTS: The TNFalpha secretion and TNFalphamRNA expression level of the Mphi from mice treated by lanthanum chloride processed LPS were obviously lower than those by LPS only (P < 0.01). The mortality of the mice treated by lethal dose of LPS which has been processed by lanthanum chloride was significantly lower than that by lethal dose of LPS only. CONCLUSION: Lanthanum chloride possessed the capacity of lowering down the toxicity of LPS and inhibiting the TNFalpha secretion and TNFalphamRNA expression in murine Mphi stimulated by LPS.

Animals↗

PubMed2002

[A review of operative treatment of hypospadias in twelve years].

OBJECTIVES: To evaluate the relationship between the operative methods and the therapeutic results of the patients with hypospadias. METHODS: Nine operative types and different tissue materials taken in hypospadias operations in the past 12 years were retrospectively analyzed. RESULTS: The operative types and tissue materials had significantly effects on the therapeutic results besides the clinical experience of the operators. The cure rates of Tunneltron Urethroplasty, Preputial island flap urethroplasty and Bladder mucosa graft urethroplasty were 86.4%, 83.3% and 83.0% respectively. CONCLUSIONS: All the nine types and different tissue materials of Hypospadias operations have its own advantages and disadvantages. They are worth further study and improvement.

Adolescent↗

PubMed2002

[Determination of the conversion of air oxidation of penicillin derivatives by high performance liquid chromatography].

In air oxidation of penicillin G p-methoxybenzyl ester (PGPMB) to its sulfoxides (PGPMBO), sol-gel technique was employed to encapsulate the catalyst Co (acac)3, by which the reaction was run under heterogeneous conditions. A reversed-phase high performance liquid chromatographic method was established for the determination of the conversion of this reaction. The analysis of PGPMBO was carried out on a C18 column (4.6 mm i.d. x 150 mm, 10 microm) with the mobile phase of methanol-water (85:15, V/V), at a flow rate of 1 mL min(-1) and with detection wavelength of 270 nm. The linearity of the calibration curve of PGPMBO was obtained over the range of 0.05 g x L(-1) - 0.40 g x L(-1) with a relative coefficient of 0.999 2. The highest conversion was 98.8%. The method can be applied to determine this conversion promptly in the reaction system.

Anti-Bacterial Agents↗

PubMed2000

[Application of Metaphase-Fluorescence in Situ Hybridization to the Diagnosis of Acute Promyelocytic Leukemia and the Detection of Minimal Residual Disease]

To investigate the value of metaphase-fluorescence in situ hybridization (M-FISH) in the diagnosis of acute promyelocytic leukemia (APL) and the detection of its minimal residual disease (MRD), 10 cases of untreated acute myeloid leukemia (AML) (de novo APL 5 cases, relapsed APL 3 cases, AML-M(1) and AML-M(5) one case each) diagnosis by cell morphology at presentation and 10 cases of APL after complete remission (CR) were studied by M-FISH using a whole chromosome 17 painting probe labeled by digoxigenin and the results were compared with that of conventional cytogenetic examination and reverse transcription-polymerase chain reaction (RT-PCR). Among 10 untreated AML cases, 7 had positive M-FISH results, of whom 4 had t (15;17) translocation, 3 had normal karyotype. Six of them had PML/RARalpha fusion transcript except one, in whom RT-PCR did not be performed; 3 had negative M-FISH results, of whom one had del (2q) x 2 abnormalities, who was RT-PCR-positive for PML/RARalpha fusion transcript; one had complex karyotype abnormalities, whose RT-PCR was negative for PML/RARalpha fusion transcript; one had t (9;22) translocation, whose RT-PCR was negative for PML/RARalpha fusion transcript, but positive for BCR/ABL fusion transcript. Thus the diagnosis of AML-M(3) was revised as AML-M(2) for the latter two cases. 10 APL cases after CR had normal karyotype, but 12/15 M-FISH assays detected 1 - 5 t (15;17) positive cells in 9 of them. This finding is compatible with the results of RT-PCR assays. Leukemia relapse was seen in one case, and two positive M-FISH results were appeared in the 2 assays at a 13 months' interval. This study suggests that M-FISH had important practical value in the diagnosis of APL and the detection of MRD, and that it is less sensitive than RT-PCR, however, it seems to be more potential for prediction of the relapse of leukemia due to its capacity of detecting quantitatively the chromosome translocation in proliferative cells.

Journal Article↗

PubMedDate not supplied

Management for postoperative complications of breast augmentation by injected polyacrylamide hydrogel.

Polyacrylamide hydrogel, a new biomaterial, has been used for injected breast augmentation in China since 1997. A series of 30 patients with various complications after injected polyacrylamide hydrogel visited the author's department. Most of these patients had undergone injection of both breasts. The average age of the patients was 27.6 years, and the time of consultation for the complications was from 3 to 36 months postopertively. Nearly all the patients had breast lumps and other common complications including breast pain, disfigurement, and infection. Ultrasound examination showed diffuse, irregular, anechoic zones of mammary tissue. Pathologic results indicated inflammatory cell infiltration and fibrous capsular formation. An open suction technique and partial mastectomies via periareolar incisions were performed for the all patients. Most of their symptoms were relieved after removal of the polyacrylamide hydrogel. Only one patient had undergone immediate breast reconstruction with implants, whereas five patients had received breast implants secondarily via an axillary incision. The authors conclude that polyacrylamide hydrogel should be prohibited for injected breast augmentation before more scientific data are available about the long effect of the gel in breast tissue.

Acrylic Resins↗

PubMedDate not supplied

P38 activation mediates amyloid-beta cytotoxicity.

Amyloid-beta is a leading candidate factor in the development of Alzheimer disease (AD), however the mechanisms involved are unclear. As such, there has been considerable interest in evidence showing that the neuronal damage caused by amyloid-beta is mediated by oxidative stress. Notably, oxidative stress leads to activation of stress-activated protein kinases, which we and others have shown are also involved in AD pathogenesis. One SAPK in particular, p38, appears to be crucial in AD and therefore, in the current study, we investigated the role of p38 activation in amyloid-beta cytotoxicity. Our data showed p38 activation was induced by amyloid-beta in a concentration-dependent manner in M17 human neuroblastoma cells. Notably, amyloid-beta toxicity was significantly decreased by inhibition of p38 activity by overexpressing dominant negative p38. Consistent with this, in primary cortical neurons amyloid-beta also induced p38 activation and amyloid-beta toxicity was significantly diminished when p38 was inhibited by its specific inhibitor, SB203580. Taken together, these data suggest that p38 is a key downstream effector of amyloid-beta-induced neuronal death and blocking this pathway may be of therapeutic value.

Amyloid beta-Peptides↗

PubMedDate not supplied

Antibacterial activity of vegetables and juices.

OBJECTIVE: We evaluated the antibacterial activities of various fruit and vegetable extracts on common potential pathogens including antibiotic-resistant strains. METHODS: Standardized bacterial inocula were added to serial dilutions of sterile vegetable and fruit extracts in broth, with final bacterial concentrations of 10(4-5) cells/mL. After overnight incubation at 35 degrees C, antibacterial activity was measured by minimum inhibitory and minimum bactericidal dilutions (for raw juices) or concentrations (for tea). RESULTS: Among the vegetable and fruit extracts tested, all green vegetables showed no antibacterial activity on Staphylococcus epidermidis and Klebsiella pneumoniae. All purple and red vegetable and fruit juices had antibacterial activities in dilutions ranging from 1:2 to 1:16. Garlic juice had significant activity, with bactericidal action in dilutions ranging up to 1:128 of the original juice. Tea also had significant activity, with bactericidal action in concentrations ranging up to 1.6 mg/mL, against a spectrum of pathogens including resistant strains such as methicillin- and ciprofloxacin-resistant staphylococci, vancomycin-resistant enterococci, and ciprofloxacin-resistant Pseudomonas aeruginosa. CONCLUSIONS: Tea and garlic have the potential for exploration of broader applications as antibacterial agents.

Anti-Bacterial Agents↗

PubMedDate not supplied

Dendrimer versus linear conjugate: Influence of polymeric architecture on the delivery and anticancer effect of paclitaxel.

The relative difference in polymeric architectures of dendrimer and linear bis(poly(ethylene glycol)) (PEG) polymer in conjugation with paclitaxel has been described. Paclitaxel, a poorly soluble anticancer drug, was covalently conjugated with PAMAM G4 hydroxyl-terminated dendrimer and bis(PEG) polymer for the potential enhancement of drug solubility and cytotoxicity. Both conjugates were characterized by 1NMR, HPLC, and MALDI/TOF. In addition, molecular conformations of dendrimer, bis(PEG), paclitaxel, and its polymeric conjugates were studied by molecular modeling. Hydrolysis of the ester bond in the conjugate was analyzed by HPLC using esterase hydrolyzing enzyme. In vitro cytotoxicity of dendrimer, bis(PEG), paclitaxel, and polymeric conjugates containing paclitaxel was evaluated using A2780 human ovarian carcinoma cells. Cytotoxicity increased by 10-fold with PAMAM dendrimer-succinic acid-paclitaxel conjugate when compared with free nonconjugated drug. Data obtained indicate that the nanosized dendritic polymer conjugates can be used with good success as anticancer drug carriers.

Antineoplastic Agents↗

PubMedDate not supplied

Characterization of biodegradation intermediates of nonionic surfactants by MALDI-MS. 2. Oxidative biodegradation profiles of uniform octylphenol polyethoxylate in 18O-labeled water.

This paper reports the characterization of the biodegradation intermediates of octylphenol octaethoxylate (OP(8)EO) by means of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The biodegradation test study was carried out in a pure culture (Pseudomonas putida S-5) under aerobic conditions using OP(8)EO as the sole carbon source and (18)O-labeled water as an incubation medium. In the MALDI-MS spectra of biodegraded samples, a series of OP(n)EO molecules with n = 2-8 EO units and their corresponding carboxylic acid products (OP(n)EC) were observed. The use of purified OP(8)EO enabled one to distinguish the shortened OPEO molecules as biodegradation intermediates. Furthermore, the formation of OP(8)EC (the oxidized product of OP(8)EO) supported the notion that terminal oxidation is a step in the biodegradation process. When biodegradation study was carried out in (18)O-labeled water, incorporation of (18)O atoms into the carboxyl group was observed for OPEC, while no incorporation was observed for the shortened OPEO products. These results could provide some rationale to the biodegradation mechanism of alkylphenol polyethoxylates.

Biodegradation, Environmental↗