Biomedical subjects

Jing Liu

Publications and source records attributed to Jing Liu.

At least 217 records · Page 12Linked to original sources

PubMed2005

[Soluble expression and characterization of disulfide bond-rich subdomains of membrane protein p185 in Escherichia coli].

Transmembrane protein p185 (the product of Her2/c-erbB-2 gene) is a member of the epidermal growth factor receptor (EGFR) family. Its overexpression was found in about 30% of breast cancer. It is essential to obtain soluble extracellular domain (ECD) of p185, especially disulfide bond rich domains, for identifying the epitopes of anti-p185 antibodies and researching the interrelationship between the antigen and antibody. The disulfide bond rich domain I-II and domain IV of p185 ECD were amplified from plasmid pBabe/erbB-2 by PCR respectively. These two fragments were inserted into pGEX/4T-1 vector, transfected into E. coli Origami B (DE3) pLysS and expressed inductively by low concentration of IPTG and low temperature overnight. After the pressure lysis of cells, the supernatants were analyzed by SDS-PAGE and the result demonstrated that this GST-fusion protein was expressed solubly in the amount of 10-15 mg/L. By the ELISA, Western blot and other immunological assays, the fusion proteins and their GST cut-off derivates both showed binding activities with several anti-p185 antibodies respectively. These results indicated that it was a feasible and effectual method to express disulfide bond rich domain I-II and domain IV of p185 ECD and this method may also be used to express other disulfide bond rich proteins.

Antibodies, Monoclonal↗

PubMed2005

[Comparative study on the influence of arginine hydrochloride and arginine acetate on the immune function and acid-base balance in rabbits with severe burns].

OBJECTIVE: To investigate the influence of arginine hydrochloride and arginine acetate on the immune function and acid-base balance in rabbits with severe burns. METHODS: One hundred and ten flap-eared rabbits were used in the study, in which 8 served as normal control, while the rest were inflicted with 30% TBSA full thickness burn. All the rabbits were divided into 10 groups, i.e. normal control (C, n = 14), burn control (B, n = 14, with intravenous infusion of Ringer's solution), 0.3 g/kg arginine hydrochloride (AH, n = 12), 0.3 g/kg arginine acetate (AA, n = 10), 0.6 g/kg AH (n = 10), and 0.6g/kg AA (n = 10) groups, 1.2 g/kg AH (n = 10), 1.2 g/kg AA (n = 10), 2.4 g/kg AA (n = 14) and 2.4 g/kg AH (n = 12) groups. AA and AH in different doses were fed to rabbits in corresponding groups 2 times a day for 7 days. The changes in the immune function, acid-base balance, chloride ion metabolism, and mortality were determined. RESULTS: Disorder in immune system was found after severe burns, with enhanced immune function at the beginning and weakening afterwards. The lymphocytic transformation rate, the CD4/CD8 ratio, the phagocytosis rate and the chemotactic index of white blood cells on 7 post burn day (PBD) were obviously lower in B group compared with C group (P < 0.05 or 0.01). These indices were obviously higher in 1.2, 2.4 g/kg AA and AH groups than those in B group on 7 PBD (P < 0.05 or 0.01). There was no difference in improvement of immune functions between 0.3, 0.6g/kg AH, AA group and B group. The values of blood pH, base excess (BE), buffer base (BB), HCO(3)(-) level in AH group were significantly lower than those in C group on 7 PBD (P < 0.05 or 0.01), while there were no obvious changes in AA group, they were obviously higher than those in AH group (P < 0.05 or 0.01). The contents of chloride ion in but 2.4 g/kg AH group during 5 to 7 PBD were obviously higher than those in C group and 2.4 g/kg AA group (P < 0.05 or 0.01), while no difference was found between 2.4 g/kg AA and C groups. The mortality in B group was obviously higher than that in 0.3, 0.6, 1.2 g/kg AH and AA groups (P < 0.05 or 0.01), but significantly lower than that in 2.4 g/kg AA and AH groups (P < 0.05). CONCLUSION: Disorders in immune functions were observed in severely burned rabbits. Administration of arginine acetate as well as arginine hydrochloride could enhance the immune function, but arginine acetate seemed to be safer than arginine hydrochloride. Excessive dosage should be avoided to prevent a rise of the mortality.

Acetates↗

PubMed2005

[A cohort study on trends of cardiovascular disease risk factors in Beijing during 1992-2002].

OBJECTIVE: To evaluate the trends of cardiovascular disease (CVD) risk factors between 1992 and 2002 (10 years) in a cohort of Beijing. METHODS: Two separate surveys were carried out for a cohort (2740 subjects) in 1992 and 2002 according to methods of the WHO MONICA project. Systolic blood pressure (SBP) and diastolic blood pressure (DBP), body mass index (BMI), waist circumference (WC) and hip circumference (HC), serum total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), triglyceride (TG), glucose, prevalence of hypertension, rate of hypertension treatment and control were compared between 1992 and 2002. RESULTS: (1) Comparisons of the same age groups showed that CVD risk factors increased significantly during the 10 year period from 1992 to 2002. (2) Nineteen percent of the subjects with optimal BP in 1992 became hypertensive in 2002, and 45.3% of normal BP subjects in 1992 became hypertensive in 2002. (3) 43.8% of the subjects with normal blood lipid in 1992 became hyperlipidemia in 2002. (4) 37.0% of the subjects with normal BMI in 1992 became overweight in 2002, and 43.7% of subjects with normal WC in 1992 became high WC in 2002. (5) 14.6% of the subjects without metabolic syndrome in 1992 became with metabolic syndrome in 2002. CONCLUSIONS: The levels of CVD risk factors in this cohort increased significantly in a 10 year period from 1992 to 2002. Most of the risk factors were related to unhealthy life styles. To modify unhealthy life style and control the increasing rate of major risk factors are the key to reduce CVD incidence.

Adult↗

PubMed2005

[Association between serum uric acid and triglyceride in a Chinese community].

OBJECTIVE: To Study the association between the level of serum uric acid and triglyceride in a Chinese population. METHODS: In 1999, a cross-sectional study was carried out in a natural population of Beijing, using stratified-random sampling method. Serum uric acid and triglyceride were measured in 1239 subjects. RESULTS: The prevalence of hypertriglyceridemia significantly increased with increased level of serum uric acid among both the men and women. After adjusting BMI, HOMA index and alcohol consumption level with stratified methods, the incidence of hypertriglyceridemia increased with increasing level of basal serum uric acid in different levels of BMI, HOMA index and alcohol consumption. After adjusting gender, age, BMI, HOMA index, total cholesterol, smoking and alcohol consumption, the results of multivariate logistic regression analyses indicated that the odds ratio for hypertriglyceridemia as compared with the lowest quartile of serum uric acid was 1.26 (P = 0.28) for the second quartile, 1.88 (P = 0.002) for the third quartile, and 3.36 (P < 0.001) for the highest quartile. CONCLUSIONS: Serum uric acid level was strongly associated with triglyceride independent of age, genders, smoking, alcohol consumption, obesity and insulin resistance.

Adult↗

PubMed2005

[Inhibitory effect of ardipusilloside-I on Lewis pulmonary carcinoma and hepatocarcinoma SMMC-7721].

OBJECTIVE: To study the antitumor effect of ardipusilloside-I (ADS-I) on Lewis pulmonary carcinoma and hepatocarcinoma SMMC-7721. METHODS: Lewis pulmonary metastasizing model was made by Sc. diluted 3-time 20 microl cancer cells in the right sole of C57BL/6 mice, after we treated the mice 14 days with ADS-I orally, cut the neoplasia-foot and weighed, we calculated the inhibitory rate in situ, then put the mice to death after being administrated 11 days continuously, counted the lung medtastasis colony and calculated the metastasis inhibitory rate; Human being hepatocarcinoma model was made by sc. in the back 5 x 10(6)/ml SMMC-7721 cells per BALB/c/nu nude mice, after we treated them orally 16 days with ADS-I continuously, measured the volume of tumor growth and body weight, and drew the growth curve, we detached the tumor and calculated the inhibitory rate of tumor growth in the end. RESULTS: Lewis pulmonary carcinoma inhibitory rate in situ and lung transfer inhibitory rate of ADS-I (25 mg/kg - 100 mg/kg) were between 40.5% and 54.0%, 45.4% and 69.1% respectively; Inhibitory rate of hepatocarcinoma SMMC-7721 was between 45.6% and 56.3%. CONCLUSIONS: ADS-I has inhibitory effect on Lewis pulmonary metastasis carcinoma and hepatocarcinoma SMMC-7721 carcinoma.

Animals↗

PubMed2005

[Function analysis of the family-specific CTL induced by peptides derived from IgHV gene framework region of B-cell malignance].

OBJECTIVE: To identify immune epitopes existed in the framework region (FR) of the IgHV protein of B-cell malignance, and explore the use of these FR-derived peptides to induce the family specific immune response in vitro, in order to explore the possibility of a new IgHV gene family-specific immunotherapy for B-cell malignance. METHODS: Bioinformatics was used for predicting T cell epitopes in IgHV protein. Peptides of interest were synthesized in vitro. T2 cell binding assay was performed to determine the binding ability of the peptides to HLA-A*0201 molecules. Peptide/HLA tetramer staining was used to detect the number of peptide-specific cytotoxic T lymphocytes (CTLs). Cytotoxicity assay was used to determine killing activity. RESULTS: Twelve peptides that were common to seven IgHV gene subfamilies were identified, and 10 (83%) of them were located in the FR of IgHV protein. The synthesized peptides up-regulated HLA*0201 molecules fluorescence intensity on cell surfaces of T2. By using an antigen-specific T-cell expansion system in vitro, the peripheral blood mononuclear cells (PBMNC) from a healthy HLA-A0201 donor were stimulated weekly by autologous PBMNC loaded with the peptide as antigen presenting cells (APC), and the peptide-specific CTLs were demonstrated to be generated successfully in the healthy donors. The frequency of CD8 and peptide/HLA tetramer double positive cells in the gated lymphocyte population was 0.38% before stimulation and increased to 49.38 % after four times stimulation. Cytotoxicity assay indicated that these CTLs were capable of killing the HLA-A*0201, IgHV1 (+) lymphoma cells. Furthermore, the generated CTL could not kill the target cell loaded with the IgHV3 peptide, indicating that the cytotoxicity is family-specific. CONCLUSION: Peptides derived from the IgHV protein FR can successfully induce the generation of peptide-specific CTLs in vitro. These CTLs are capable of killing the lymphoma cell belonged to the same subfamily in a peptide-specific and MHC-restricted way. These findings could potentially form the basis of broadening application of immunoglobulin-directed immunotherapy in B-cell malignancies.

Cells, Cultured↗

PubMed2005

[Neurological complications following haploidentical bone marrow transplantation].

UNLABELLED: To explore the occurrence patterns of neurological complications following haploidentical bone marrow transplantation, a series of clinical data as the onset time, etiology, choices of therapies and prognosis in 10 patients with neurological disorders were summarized. The results showed that complications occurred in 10 out of 74 patients after bone marrow transplantation, which include 3 with encephalorrhagia, 3 infection, 1 epilepsy, 1 Guillian-Barr's syndrome, 1 encephalopathy and 1 schizophrenia. 4 patients died of neurological complications. IN CONCLUSION: neurological complications commonly occurred in haploidentical bone marrow transplantation, and encephalorrhagia might be the main indication that needs intensive care. Moreover, central nerve system infection and peripheral nerve diseases associated with slow immune reconstitution should have clinical interests.

Adolescent↗

PubMed2005

[Observation of the L929 cell membrane after infrasound exposure with atomic force microscope].

OBJECTIVE: To observe the changes of L929 cell membrane with atomic force microscope (AFM) after infrasound exposure and to explore the mechanisms of effect of infrasound on cell membrane. METHODS: After primary culture, the L929 cells were exposed to infrasound with intensity output of 130 dB and frequency of 16 Hz 2 hours each day for 3 days. The subsequent changes in the membrane of the control cells and the cells exposed to the infrasound were determined by nano-scale scanning with AFM. RESULTS: After infrasound exposure, the normal prominence of the membrane became short and the dent became shallow in the 7.5 microm x 7.5 microm and 4.0 microm x 4.0 microm photographs. The prominence appeared as cobblestones. The surface of the membrane became smooth. CONCLUSION: The membrane structure of the L929 cells can be changed by infrasound exposure with intensity of 130 dB and frequency of 16 Hz. The change might be one of the characteristics of effect of infrasound on cell membrane.

Animals↗

PubMed2005

[Level of vitamin K-dependent coagulation factors in premature infants and the influence of maternal antenatal administration of vitamin K1 on their activity].

OBJECTIVE: Infants less than 35 weeks of gestational age are susceptible to peri-/intraventricular hemorrhage (PIVH). This may be due in part to low concentrations of vitamin K-dependent coagulation factors. This study was conducted to determine the umbilical cord blood activities of vitamin K-dependent coagulation factors II, VII, IX and X in premature infants to understand whether preterm infants have absence status of these factors the changes of theses factors' activities in premature infants' umbilical blood after vitamin K(1) was given to mothers antenatally and the preventing effectiveness of PIVH after maternal antenatal supplement of vitamin K(1). METHODS: Pregnant women in preterm labor at less than 35 weeks of gestational age were randomly selected to receive antenatal vitamin K(1) intramuscular or intravenous injections 10 mg per day for 2 to 7 days (vitamin K(1) group), or no vitamin K(1) treatment (control group). Dexamethone was antenatally given to both groups of pregnant women routinely. Vitamin K(1) group had 44 infants and the control group had 133 infants. During the same period, thirty full-term neonates' cord blood samples were obtained to determine theses factors to compare with those from the premature infants. The cranial ultrasound was performed by a same physician to understand whether the neonates were complicated with PIVH and its severity. RESULTS: The levels of vitamin K-dependent coagulation factors in umbilical blood in control group were significantly lower than those in full-term infants' cord blood (P < 0.05). However, in vitamin K(1) group, supplement of vitamin K(1) antenatally could significantly increase activities of factors II, VII and X in preterm infants' cord blood (P < 0.05). The total occurrence rates of PIVH in vitamin K(1) group and control group were 31.8% and 52.6%, respectively, (P = 0.017), and the frequency of severe PIVH in vitamin K(1) group and control group was 2.3% and 12.0%, respectively (P = 0.057). CONCLUSION: Preterm infants have absence status of vitamin K-dependent coagulation factors. Administration of vitamin K(1) to pregnant women at less than 35 weeks of gestational age resulted in significantly improved activities of vitamin K-dependent coagulation factors II, VII, and X, and a significantly decreased frequency of PIVH and less severe hemorrhage in preterm infants.

Blood Coagulation Factors↗

PubMed2005

[Screening of a phenanthrene-degrading bacterium and its degradation conditions].

Several PAHs-degrading bacteria were isolated from the soil near a petrochemicals factory, and one strain Fl0a identified as B. sphaericus was chosen for use. The study on the phenanthrene-degradation potential of the strain and its affecting factors showed that at 28 degrees C, the degradation rate of phenanthrene (50 mg x L(-1)) was 98.12% after 27 hours rotary culture, and 98.47% after 84 hours static culture. F10a had a good phenanthrene-degradation capability when the pH was 4, 6 and 8, but its growth was inhibited when pH was 10. Cr2+ was toxic to the strain, Cu2+ could delay the degradation of phenanthrene, while Zn2+ and Pb2+ had no significant effects. The degradation rate of phenanthrene (200 mg x L(-1)) was 99.6% after 84 hours rotary culture. A significant positive relationship was found between bacterial growth and phenanthrene degradation.

Biodegradation, Environmental↗

PubMed2004

Cardiovascular effects of endomorphins in alloxan-induced diabetic rats.

Endomorphins, the endogenous, potent and selective mu-opioid receptor agonists, have been shown to decrease systemic arterial pressure (SAP) in rats. In the present study, responses to endomorphins were investigated in systemic vascular bed of alloxan-induced diabetic rats and in non-diabetic rats. Diabetes was induced by alloxan (220 mg/kg, i.p.) in male Wistar rats. At 4-5 weeks after the onset of diabetes, intravenous injections of endomorphins (1-30 nmol/kg) led to an increase of SAP and heart rate (HR) consistently and dosed-dependently. SAP increased 7.68+/-3.73, 11.19+/-4.55, 21.19+/-2.94 and 27.48+/-6.21% from the baseline at the 1, 3, 10 and 30 nmol/kg dose, respectively, of endomorphin 1 (n=4; p<0.05), and similar changes were observed in response to endomorphin 2. The hypertension could be antagonized markedly by i.p. 2 mg/kg of naloxone. On the other hand, bilateral vagotomy would attenuate the effects of hypertension and diminished the changes of HR in response to endomorphins. With diabetic rats, 6-10 weeks after the induction of diabetes, intravenous injections of endomorphins produced non-dose-related various changes in SAP, such as a single decrease, or a single increase, or biphasic changes characterized by an initial decrease followed by a secondary increase, or no change at all. These results suggest that diabetes may lead to the dysfunction of the cardiovascular system in response to endomorphins. Furthermore, the diabetic rats of 4-5 weeks after alloxan-treatment, the increase in SAP and HR caused by i.v. endomorphins might be explained by a changed effect of vagus and by a naloxone-sensitive mechanism.

Analgesics, Opioid↗

PubMed2004

Effects of lycorine on HL-60 cells via arresting cell cycle and inducing apoptosis.

As a natural anti-cancer alkaloid extracted from Amaryllidaceae, lycorine shows various biological effects on tumor cells. The survival rate of HL-60 cells exposed to lycorine was decreased in a dose-dependent manner with 1 microM as the 50% inhibitory concentration (IC50), cell growth was slowed down by arresting cell cycle at G2/M phase, and cell regeneration potential was inhibited. HL-60 cells exhibited typical apoptotic morphological changes, apoptotic DNA "ladder" pattern, and sub-G1 peak in cell phase distribution, showing apoptosis of HL-60 cells. To further understand the apoptotic molecular mechanism of lycorine on HL-60 cells, caspase activity was tested by colorimetric assay, and the expression of Bcl-2 and Bax proteins was examined by Western blotting. The increase of caspase-8, -9, -3 activities demonstrated that caspase was a key mediator of apoptotic pathways induced by lycorine. Under-expression of Bcl-2 and increase of Bax:Bcl-2 ratio showed that Bcl-2 family proteins were involved in apoptosis. Our finding suggests that lycorine can suppress leukemia growth and reduce cell survival via arresting cell cycle and inducing apoptosis of tumor cells.

Amaryllidaceae Alkaloids↗

PubMed2004

Predictors of motor development in children prenatally exposed to cocaine.

The current study examined the pattern of motor development across the first 18 months of life in infants with in utero exposure to cocaine to determine how prenatal drug effects and level of exposure relates to motor development. Motor development was examined at 1, 4, 12, and 18 months of age (corrected for prematurity). Infants were divided into cocaine exposed (n=392) and comparison (n=776) groups. Exposure status was determined by meconium assay and maternal self-report with alcohol, marijuana, tobacco, and opiates present in both groups. Motor skills were assessed at 1 month using the NICU Network Neurobehavioral Scale (NNNS), at 4 months using the posture and fine motor assessment of infants (PFMAI), at 12 months using the Bayley Scales of Infant Development-Second Edition (BSID-II), and at 18 months using the Peabody Developmental Motor Scales (PDMS). Examiners masked to exposure status performed all assessments. Motor scores were converted to standard (z) scores, and hierarchical linear modeling (HLM) was used to examine the change in motor skills from 1 to 18 months of age. Infants with exposure to cocaine showed low motor skills at their initial status of 1 month but displayed significant increases over time. Both higher and lower levels of tobacco use related to poorer motor performance on average. Heavy cocaine use related to poorer motor performance as compared to no use, but there were no effects of level of cocaine use on change in motor skills.

Child Development↗

PubMed2004

Preparation and characterization of a single-chain calcineurin-calmodulin complex.

Calcineurin (CN), a Ca(2+)/calmodulin (CaM)-dependent serine/threonine protein phosphatase, is a heterodimer composed of a catalytic subunit (CNA) and a regulatory subunit (CNB). The activity of CNA is under the control of two functionally distinct, but structurally similar Ca(2+)-regulated proteins, CaM and CNB. The crystal structure of the holoenzyme reveals that the N-terminus and C-terminus of CNB and the N-terminus of CNA each have a long arm not involved in the active site. We constructed a fusion of the genes of CaM, CNB and CNA in that order using linker primers containing six and ten codons of glycine. A single-chain CaM-CNB-CNA (CBA) complex was expressed and purified to near homogeneity. The single-chain complex was fully soluble, and had biochemical properties and kinetic parameters similar to single-chain CNB-CNA (BA) activated by CaM. It was not regulated by CaM and CNB, but was strongly stimulated by Mn2+, Ni2+ and Mg2+. Intrinsic fluorescence spectroscopy of the complex showed a change in the environment of tryptophan in the presence of Ca2+ and circular dichroism (CD) spectropolarimetry revealed an increase in alpha-helical content. Our findings suggest that fusion of CaM, CNB and CNA does not prevent the structural changes required for their functioning; in particular, CaM within the complex could still interact correctly with CN in the presence of Ca2+.

Binding Sites↗

PubMed2004

Molecular cloning and expression of two chicken invariant chain isoforms produced by alternative splicing.

The biosynthesis of distinct forms of the invariant chain (Ii) protein from a unique gene as the result of differential splicing patterns has been observed in humans and mice. However, there have been no reports on the existence of Ii isoforms in avian species. In the present study, we identified two chicken Ii cDNAs by RT-PCR and RACE, and examined the Ii gene copy number, mRNA expression and protein expression by Southern blotting, Northern blotting and immunofluorescence confocal microscopy, respectively. One of the Ii cDNAs, named Ii-1, was 1,151 bp in length, and had an open reading frame (ORF) of 672 nucleotides, in agreement with a previously identified chicken Ii sequence; the other, named Ii-2, was 1,337 bp long and had an ORF of 861 nucleotides. Southern blotting confirmed that these cDNAs were derived from a single copy gene. Northern blotting performed with total RNA from various tissues of 6-week-old chickens revealed high levels of Ii-1 and Ii-2 mRNA expression in the spleen and bursa of Fabricius, and low levels of Ii-1 expression in the thymus, heart and liver, while Ii-2 was not expressed in these tissues. High levels of expression of both Ii isoforms were detected in the spleen and bursa of Fabricius during late embryogenesis. Immunofluorescence staining showed that Ii proteins were expressed in the cell membranes of the splenocytes. These data suggest that chicken Ii exists in two isoforms resulting from alternative splicing, and is strongly expressed in the major immune organs.

Alternative Splicing↗

PubMed2004

Family-based association study between autism and glutamate receptor 6 gene in Chinese Han trios.

The glutamate pathways are involved in diverse processes such as learning and memory, epilepsy, and they play important roles in neural plasticity, neural development, and neurodegeneration. It has been proposed that autism could be a hypoglutamatergic disorder. Recently, Jamain et al. reported that the glutamate receptor 6 (GluR6 or GRIK2) is in linkage disequilibrium with autism. In the present study, the transmission disequilibrium test (TDT) and the haplotype transmission were performed to analyze the four SNPs (SNP1: rs995640; SNP2: rs2227281; SNP3: rs2227283; SNP4: rs2235076) of GluR6 in 174 Chinese Han parent-offspring trios. The TDT demonstrated that the two SNPs (SNP2 and SNP3) showed preferential transmission (TDT P = 0.032). The global chi(2) test for haplotype transmission also revealed an association between GluR6 and autism (chi(2) = 10.78, df = 3, P = 0.013). Our results suggested that GluR6 is in linkage disequilibrium with autism.

Alleles↗

PubMed2004

Short-term BOD (BODst) as a parameter for on-line monitoring of biological treatment process; Part II: instrumentation of integrated flow injection analysis (FIA) system for BODst estimation.

An instrument with integrated flow injection analysis (FIA) system has been developed for on-line monitoring a process for conversion of biomass under field condition. The instrument consists of a newly designed biosensor for easy renewal of the bio-receptor without disassembling the sensor, a FIA controller for controlling the analysis operations, and a computer-based data acquisition system for data recording and processing. The instrument performed a sequence operations automatically including preparation of sample in the desired concentration, sample loading, sample injection, signal recording, data processing, and self-cleaning of the system. This makes the instrument being an interesting and promising device for on-line process monitoring.

Bacteria, Aerobic↗

PubMed2004

Short-term BOD (BODst) as a parameter for on-line monitoring of biological treatment process. Part I. A novel design of BOD biosensor for easy renewal of bio-receptor.

A novel design of a biochemical oxygen demand (BOD) biosensor has been developed for on-line monitoring of easily biodegradable organic compounds in aqueous samples. The biological recognition element of the sensor could be easily renewed by injecting new bacterial paste without disassembling the sensor system. The sensor measurements were carried out in the initial-rate mode using a flow injection (FI) system, resulting in 60 s for one sample analysis followed by a recovery time less than 10 min. The sensor performance achieved showed a wide detection linearity over the range of 5-700 mg BOD5.l(-1) and a generally good agreement between the BOD values estimated by the biosensor and the conventional 5-day test. Furthermore, the precision test was in the control range (i.e. repeatability < or = /+/-7.5%/, reproducibility < or = /+/-7.3%/). The sensor could be used over 1 week in continuous test, however, the best performance was found within the first 24 h where standard deviation of the sensor response was +/-2.4%. The design of the sensor allows easy and fast renewal of the cells used as sensing elements. Replacement of biological recognition element and calibration of the sensor responses can be performed in a rather simple procedure on a daily regular basis. By using a mixed culture as the bio-receptor, one gets a sensor that reacts to a wide range of substrates. The new sensor construction will thus allow fast and convenient replacement of the bio-receptor and on-line assay of a broad range of substrates. This makes the sensor being an interesting and promising candidate for on-line monitoring of biological treatment process.

Bacteria, Aerobic↗