Biomedical subjects

Z Tang

Publications and source records attributed to Z Tang.

At least 55 records · Page 3Linked to original sources

PubMed2001

Comparison of in vivo dopamine D2 receptor binding of [(123)I]AIBZM and [(123)I]IBZM in rat brain.

[(123)I]AIBZM, (S)-5-[(123)I]-Iodo-N-[(1-ethyl-2-pyrrolidinyl)]methyl-4-amine-2-methoxybenzamide is a derivative with high affinity for the D2 receptor. Labeling was achieved by the Iodogen method. The in vivo affinity for the D2 receptor and the biological characteristics were performed in rats. The brain uptake of [(123)I]AIBZM was significantly lower, however the striatum/cerebellum ratio (2h p.i.) was higher than that of [(123)I]IBZM. Because of the high affinity and its possibly lower unspecific binding compared to [(123)I]IBZM, [(123)I]AIBZM may be a potential imaging agent for the D2 dopamine receptor.

Animals↗

PubMed2001

[Study of the cytotoxity against human hepatocellular carcinoma cells induced by the MAGE-1 gene modified dendritic cells].

OBJECTIVE: To genetically modify dendritic cells (DC) with a tumor associated antigen gene MAGE-1 and to observe in vitro the cytotoxic effect induced by this genetically modified DC against human hepatocellular carcinoma (HCC) cell line SMMC7721, thus giving a primary verification of the possibility of this genetically modified DC to induce specific antitumor immunity against HCC and serving as a new type of vaccine. METHODS: The MAGE-1 gene was inserted into the retrovirus vector LXSN to construct the recombinant retrovirus LMSN. The monocyte-derived DCs were transfected by LMSN and control virus LXSN respectively as well as a third group was set up as non-transfected control. The MAGE-1 gene expression in LMSN transfected DC was identified by Western blot and the in vitro cytotoxities against SMMC7721 induced by three groups of DC were tested by MTT assay. RESULTS: A recombinant retrovirus LMSN containing the tumor rejection antigen gene MAGE-1 was successfully constructed and the MAGE-1 gene expression in LMSN transfected human monocyte-derived DC was induced. The LMSN transfected DC could induce very high lytic activity against SMMC7721 in vitro with the lytic activity of 78.9%+/-3.6%. Nevertheless, the LXSN transfected DC and non-transfected DC only induced relatively lower lytic activity as 34.7%+/-4.3% and 3.9%+/-2.0%, respectively. The difference of the lytic activities between those three groups as statistically significant (P<0.01). CONCLUSIONS: The MAGE-1 gene transfected DC can induce higher in vitro cytotoxicity against SMMC7721, suggesting the possibility of this genetically modified DC to induce specific antitumor activity and to serve as a new type of vaccine for HCC.

Animals↗

PubMed2001

[Effects of interferon-alpha on recurrence and metastasis of hepatocellular carcinoma after curative resection in nude mice].

OBJECTIVE: To study the effect of interferon-alpha (IFN-alpha) on the recurrence and metastasis of hepatocellular carcinoma (HCC) in nude mice, and to clarify if there is synergistic effect treated by combination of IFN-alpha and all-trans retinoic acid (ATRA). METHODS: The effect of IFN-alpha and/or ATRA on the proliferation of HCC cell lines was measured in vitro. The metastatic model of human HCC in nude mice LCI-D20 was used in present study. Curative resection was performed at 10th day after implantation in 44 nude mice. Drugs were given at the next day after resection. IFN-alpha was administered subcutaneously at doses of 3+/-10(5) U/day, 6+/-10(5) U/day, respectively. ATRA was administered p.o. at a dose of 20 mg/kg/day, and IFN-alpha 6+/-10(5)U/day combined with ATRA 20 mg/kg/day. The mice were sacrificed 35 days after treatment. The recurrent tumor size was measured and the presence of intrahepatic dissemination and lung metastases were recorded. RESULTS: The effect of IFN-alpha and/or ATRA on the proliferation of HCC cells SMMC7721, BEL-7402, BEL-7405, and MHCC97 was not obvious. The combination of IFN-alpha and ATRA had no synergistic effect in vitro. The lung metastatic rate, the liver recurrent rate, the size of main recurrent lesions, the number of intrahepatic disseminating nodules and the largest disseminating nodule of the controlled group was 100%(12/12), 100%(12/12), (1346.3+/-4.2 ) mm(3), 8.2+/-4.4, 864 mm(3), respectively; whereas it was 0, 87.5%(7/8), (8.7+/-2.9) mm(3), 2.3+/-0.6, and 7.8mm(3), respectively in the IFN-alpha 3+/-10(5) U/day treated group(P<0.05); 0, 12.5%(1/8), 0.5mm(3), 2, 0.5 mm(3) in the IFN-alpha 6+/-10(5)U/day treated group(P<0.05); 0, 12.5%(1/8), 1 mm(3), 2.5+/-0.7, 8 mm(3) in the IFN-alpha 3+/-10(5) U/day and ATRA treated group(P<0.05); 87.5%, 100%, (1472.6+/-5.6) mm(3), 7.3+/-3.8, 768.5 mm(3) in the ATRA treated group (P>0.05). CONCLUSIONS: IFN-alpha has an inhibitory effect on intrahepatic recurrence and lung metastasis of human HCC after curative resection in nude mice, and the effect is enhanced with increasing dose. IFN-alpha and ATRA have no synergistic effect according to in vivo and in vitro test. ATRA has no effect on recurrence and metastasis of HCC.

Animals↗

PubMed2001

[Relationship between serum matrix metalloproteinase-2 and metastasis and recurrence following radical hepatic resection in hepatocellular carcinoma].

OBJECTIVE: To study the relationship between serum matrix metalloproteinase-2 (MMP-2) and metastasis and recurrence following radical hepatic resection in hepatocellular carcinoma (HCC). METHODS: Cox's proportional hazard model was used to determine the significant clinical factor of prognosis. Meanwhile, enzyme linked immunoadsordent assay (ELISA) and northern blot analysis were adopted to detect serum and tumor tissue levels of MMP-2 respectively in HCC patients. RESULTS: Cox's proportional hazard model showed that tumor size and tumor number were significant prognostic factors of HCC patients following hepatic resection (P=0.022 and P=0.040). According to this result, we divided HCC patients into high-tendency to metastasis recurrence and low-tendency to metastasis recurrence groups. Serum levels of MMP-2 in high-tendency to metastasis recurrence following radical hepatic resection group were significantly higher than those in low-tendency group (26.39ng/m+/-2.64ng/ml vs 24.86ng+/-1.95ng/ml, P<0.05). Serum levels of MMP-2 in HCC patients performed non-radical hepatic resection group were also significantly higher than those in HCC patients performed radical hepatic resection group (29.43ng+/-3.12 ng/ml vs 25.72ng+/-2.45ng/ml, P<0.01). Northern blot analysis revealed that the changes of MMP-2 level in the serum were consistent with those of its mRNA level in the tumor tissue of HCC patients. CONCLUSIONS: Serum MMP-2 level is an indicator for metastatic recurrence following radical hepatic resection in HCC. The high levels of MMP-2 in the serum are due to high MMP-2 mRNA expression in the tumor tissue of HCC patients.

Carcinoma, Hepatocellular↗

PubMed2001

[Combined gene therapy for murine liver cancer with interleukin-18 and cytosine deaminase genes].

OBJECTIVE: To investigate the synergistic antitumor effects of murine IL-18 and CD/5FC gene therapy on mice bearing liver cancer. METHODS: A retrovirus vector pGCEN/IL-18 containing murine interleukin-18 gene was constructed. The retrovirus carrying IL-18 gene was used to infect murine liver cancer cell MM45T.Li, and proved to secret biological active IL-18. In mice bearing liver cancer, (60)Co-irradiated MM45T.Li/IL-18 vaccine was inoculated subcutaneously once a week for two weeks, and/or AdCD was injected intratumorally with 5FC injected i.p. for 8 days. RESULTS: Thirty days from the treatment, the tumor volume of control group was 1580 approximately 1625 mm(3), MM45T.Li/IL-18 vaccine group was 366 +/- 159 mm(3), AdCD/5FC group was 438 +/- 65 mm(3), and combined IL-18 and AdCD/ 5FC therapy group was 15 +/- 7 mm(3) (P<0.05). The tumor volume in single gene therapy group reduced to the smallest after three-week treatment, but grew large again, while the tumor volume in combined therapy group still remained small. The median survival time in control group was 50.0 approximately 51.5 days, MM45T.Li/IL-18 group was 65 days, AdCD/5FC group was 57 days versus 75 days for combined gene therapy group (P<0.05), and with more abundant infiltration of CD4+ and CD8+ lymphocytes around the tumor in combined gene therapy group. CONCLUSIONS: Combined gene therapy with IL-18 and CD/5FC can reduce the tumor volume and elicit the antitumor immunity of the host, which is superior to the single gene therapy for murine liver cancer.

Animals↗

PubMed2001

The clinical and pathological characteristics of Chinese patients with pauci-immune crescent glomerulonephritis.

OBJECTIVE: To investigate the clinical and pathological characteristics of pauci-immune crescent glomerulonephritis (PICGN) in Chinese patients. METHODS: During 13 years (1985-1998), 6400 patients underwent non-transplanting renal biopsy. Twenty-four patients were diagnosed as PICGN. All clinical and laboratory data of these patients were collected from the patients' records and used for detailed analysis. The diagnosis is based on clinicopathologic findings. RESULTS: Of the 24 patients, 16 were females and 8 were males, with median age of 33 years (ranged 10-76 years). Microscopic polyarteritis (MPA) (33.3%) and systemic vasculitis (8.3%) were the secondary diseases. The incidence of PICGN was 0.38% in renal biopsies and 22.9% in crescentic glomerulonephritis. Clinically, most patients (75.0%) showed rapidly progressive nephritis with enlarged kidneys. At onset, gross hematuria was noted in 58.3% of patients, hypertension in 45.8%, nephrotic syndrome in 41.7%, and oliguria in 25.0%. However, systemic symptoms were rare except for anemia. Pathologically, necrosis of glomerular capillaries (62.5%), infiltration of monocytes and neutrophil cells in glomeruli (66.7%), and vasculitis in the interstitium (53.3%) were observed. In addition, glomerulosclerosis was noted in 45.8%, severe tubular atrophy in 83.3% and interstitial fibrosis in 75.0%. Anti-neutrophil cytoplasmic antibodies (ANCAs) were positive in 52.2%. All patients except two received intensively immunosuppressive therapy. Sixteen patients were available for long-term follow up (median 29.8 months, range 8-92 months). Twelve of them had life-sustaining renal function, four had normal serum creatinine (< 124 mumol/L) and only 4 patients were dialysis-dependent. CONCLUSION: PICGN is not rare in China. Early diagnosis and administration of immunosuppressive therapy, particularly in patients with rapidly progressive glomerulonephritis (RPGN), are important for good prognosis.

Adolescent↗

PubMed2001

The distribution and significance of renal infiltrating cells in patients with diffuse crescentic glomerulonephritis.

OBJECTIVE: To study the significance and distribution of renal infiltrating cells, including monocytes (CD68+ cells), proliferative cell nuclear antigen positive cells (PCNA+ cells), CD4+ and CD8+ cells in diffuse crescent glomerulonephritis (DCGN). METHODS: Fifty-six patients with DCGN were studied, including 10 cases of anti-glomerular basement membrane (GBM)--type I DCGN, 26 immune complex--type II DCGN, and 20 cases of pauci-immune--type III DCGN. Glomerular and interstitial infiltrates of CD68+ and PCNA+ cells, and interstitial infiltrates of CD4+ and CD8+ cells were detected by using four-layer PAP methods. RESULTS: There was a significant increase of renal infiltrating CD68+, PCNA+, CD4+ and CD8+ cells in patients with DCGN compared with that in normal controls. In patients with type I DCGN, there was a higher number of renal infiltrating CD68+ and PCNA+ cells than that in patients with type II and III DCGN. A glomerular infiltrates of CD68+ and PCNA+ cells correlated with the interstitial infiltrates of CD4+ cells in type I or III DCGN patients. In lupus DCGN patients, the numbers of renal infiltrating CD68+ and PCNA+ cells were similar to vasculitis or type III DCGN patients. CONCLUSION: These findings demonstrate that the renal infiltrates of CD68+ and PCNA+ cells play an important role in patients with DCGN, that the infiltrates of CD4+ cells correlate with the infiltrates of CD68+ and PCNA+ cells may be an active marker of DCGN, and that cell-mediated immunity may contribute to crescent formation in lupus DCGN patients.

Adolescent↗

PubMed2001

Cyclosporin A treatment for idiopathic membranous nephropathy.

OBJECTIVE: To evaluate the efficacy of cyclosporin A (CSA) in the treatment of idiopathic membranous nephropathy (IMN), a prospective controlled clinical study was performed. METHODS: This study included a group of 30 IMN patients, among them 15 were treated with CSA and 15 with captopril (CAP). The diagnosis of IMN was made with exclusion of secondary forms of membranous nephropathy by extensive clinical and pathological studies. No patients received steroids or cytotoxic agents for six months prior to enrollment. In the CSA group, CSA was given at an initial dosage of 5 mg.kg-1.d-1, gradually tailed off over the first three months and maintained at 2 mg.kg-1.d-1 for 12 months. In the CAP group, CAP was given at a dosage of 37.5 mg/day. RESULTS: In the first three months, 6 (6/15) complete remissions (CR) and 2 (2/15) partial remissions (PR) were observed in the CSA group while only 2 (2/15) PRs were observed in the CAP group. Before the end of the 15-months, 8 patients in the CSA group experienced CR and 4 patients experienced PR. One CR patient relapsed as the dosage of CSA was reduced, so 7 patients remained in CR at the end of the first 15-months. No additional CR or PR was observed in the CAP group during late follow-up. At the last visit (an average follow-up time of 44 months) in the CSA-group, another 2 CR patients had relapsed and 1 CR patient shifted to PR after stopping the CSA treatment, so 4 CR and 5 PR remained in the CSA group. In the CAP group, 3 spontaneous CRs occurred beyond 1.5 year's follow-up, with 3 CR and 2 PR at the last visit. No difference was found between the averages of the initial and the last serum creatinine levels in either group. No serious adverse effects were found during CSA treatment. Re-biopsy data of three patients responsive to CSA treatment showed that no pathological improvement of glomerular basement membrane was observed, even in cases at remission. Tubulointerstitial fibrosis was found in 1 relapsed CR patient, whose serum creatinine increased above the normal range, but not in the other 2 patients whose serum creatinine remained in the normal range. CONCLUSIONS: CSA therapy at a dosage of 5 mg.kg-1.d-1 is effective in inducing remission of nephrotic syndrome in adult IMN patients within three months, with a response rate of 80%. A relatively high rate of relapse (50%) was observed within 2 years after the withdrawal of CSA treatment.

Adult↗

PubMed2001

[Clinical and radiographic evaluation of 108 dental implants after 1-year loading].

OBJECTIVE: To evaluate the clinical outcomes and a possible correlation between peri-implant mucosal inflammation and marginal bone loss in a group of Chinese patients who received IMZ and Frialit-2 implants one year after restoration. METHODS: The clinical and radiography parameters of 108 IMZ and Frialit-2 dental implants in 70 patients were measured. RESULTS: There were no signs of mobility and peri-implant radiolucencies in any of the implants. The average bone loss adjacent to implants was (0.63 +/- 0.78) mm. The prevalence of peri-implant mucosal inflammation, as indicated by suclus bleeding index (SBI) of 1.0 or more, was 32.9%. Significant correlation was found between mucosal inflammation and bone loss. The severely inflamed sites experienced greater bone loss than that of healthy or slightly inflamed sites (P < 0.05). In 92% of sites, plaque index (PLI) of more than 1 was measured on implant surfaces. The periodontal status of the remaining natural teeth in each subject was evaluated using the community periodontal index of treatment need (CPITN). Of the 70 examined patients, 15 patients needed oral hygiene instruction, 44 needed scaling and root planing, 8 patients needed periodontal surgical therapy, and only 3 did not need any periodontal treatment. CONCLUSIONS: The 1-year outcomes from this patient series indicated that IMZ and Frialit-2 implant provide satisfactory clinical results. One of the etiologic factors of alveolar bone loss around implants seems to be plaque-associated marginal inflammation. Improvement of oral hygiene, elimination of marginal tissue inflammation, and proper treatment of periodontal disease of natural teeth are needed for maintaining the implants in these observed subjects.

Adolescent↗

PubMed2001

[Clinical study on preventing endodontic interappointment pain with dexamethasone].

OBJECTIVE: To investigate the effect decreasing of the incidence of endodontic interappointment pain(EIP) by local injection of 5 mg dexamethasone. METHODS: 5 mg dexamethasone was injected submucosally at apical region of 80 teeth with asymtomatic pulp necrosis after root canal therapy, then observing the incidence of EIP and compared with control group. RESULTS: The clinical observation revealed that the incidence of EIP of dexamethasone group (10.00%) was lower than that of control group (33.75%), P < 0.01, and the level of pain was decreased. Ordinal logistic regression revealed that EIP was related to tooth location, fistula, and root canal therapy. CONCLUSION: The incidence of EIP can be reduced after 5 mg dexamethasone local injected.

Adult↗

PubMed2001

[Mechanism of contour hedgerow's control for non-point pollution in the semiarid region in northwest Hebei Province].

Slope nutrient loss is an important type of non-point pollution. The mechanism of non-point pollution control by using plenty of natural observed data in Hilly Loess region in Northwest Hebei Province, as well as combating with the large-scale artificial simulation rainfall in the field slope was analyzed. The study results show that the critical slope length was 10-15 m on the condition of rainstorm, which led to the generation of rill and made the erosion amount went up obviously. The study show that the nutrient loss in sediment was the main type of non-point pollution, the contour hedgerow the process of non-point pollution by controlling the nutrient loss in sediment, then the study got the erosion control model of the contour hedgerow.

China↗

PubMed2001

Changes in the temporomandibular joint after mandibular lengthening with different rates of distraction.

This study assessed the changes in the condyle after mandibular lengthening with 2 different rates of distraction (1 mm/day and 2 mm/day). Unilateral mandibular distraction was performed in 8 young adult goats. The animals were sacrificed 8 weeks after the completion of distraction, and the temporomandibular joint (TMJ) specimens were harvested and processed for histologic examination and histomorphometric analysis. Adaptive changes in the condyle were observed in the goats distracted at a rate of 1 mm/day, whereas degenerative alterations were found in those distracted at a rate of 2 mm/day. This study suggests that the TMJ is able to withstand the impact of distraction at a rate of 1 mm/day, but more rapid distraction may induce degeneration in the condylar cartilage.

Animals↗

PubMed2001

[Nondestructive quantitative analysis of Paracetamoli powder pharmaceutical by artificial neural network and near-infrared spectroscopy].

The application of artificial neural network for pharmaceutical nondestructive quantitative analysis were investigated. Real data set from near infrared reflectance spectra of Paracetamoli powder pharmaceutical were used to build up artificial network to predict unknown samples. The parameters affecting network were discussed. A new network evaluation criterion, the degree of approximation, was employed. Owing to good nonlinear multivariate calibration nature of ANN, the predicted results was reliable.

Acetaminophen↗

PubMed2001

[Influence of different treatment modalities on survival of patients with two -stage resection of unresectable hepatocellular carcinoma].

OBJECTIVE: To study the therapeutic results of hepatic resection for shrunk hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE) and hepatic artery ligation and chemoembolization (HALCE) in patients with unresectable HCC, and compare the influence of the above different treatment modalities on the prognosis. METHODS: Two hundred and four patients w ith pathologically proven HCC by two stage liver resection were classified into two groups: TACE group (n = 112) and HALEC group (n = 92). The patients in the TACE group received a total of 1-7 consecutive treatment courses (average, 2.4 +/- 1.2 courses). HALCE was done in 49 patients. HALCE alternating fractionated radiotherapy was employed in 7 patients and HALCE + targeting regional internal radiotherapy in 36. Shrunk tumors were surgically removed by two-stage operation in all the patients with unresectable HCC. Seven possible factors influencing the results of two-stage resection of HCC were studied. RESULTS: All the patients were followed up to June, 1999. The 1-, 3-, 5-, and 7-year survival rates were 95.7%, 69.3%, 56.5% and 44.5% after the first TACE and HALCE, respectively and 88.5%, 64.9%, 51.9% and 38.3% after resection of the shrunk HCC, respectively. The 1-, 3-, 5- and 7-year survival rates were 94.1%, 64.7%, 51.2% and 40.8% respectively in the TACE group and 96.3%, 73.9%, 61.6% and 45.2% respectively in the HALCE group. There were no statistically differences between the survival rates in the TACE and HALCE groups. The extent of cirrhotic liver and percentage of tumor necrosis were of prognostic significance. In the TACE group, the extent of cirrhotic liver, the percentage of tumor necrosis and whether capsule of shrunk tumor was complete or in complete were of prognostic significance. In the HALCE group, however, the 7 factors were not found to be statistically significant for the prognosis. CONCLUSIONS: Sequential resection should be done after cytoreduction of tumor for the patients with unresectable HCC, which might improve their survival. The extent of cirrhotic liver and the percentage of tumor necrosis after TACE or HALCE are the major factors affecting the survival of patients with two-stage operation.

Carcinoma, Hepatocellular↗

PubMed2000

N-acetylaspartylglutamate protects against transient focal cerebral ischemia in rats.

The inhibition of N-acetylated alpha-linked acidic dipeptidase (NAALADase: glutamate carboxypeptidase II) has been previously shown to protect against ischemic injury presumably through mechanisms of decreasing glutamate and increasing N-acetylaspartylglutamate (NAAG). Preventing excessive glutamate release is known to be neuroprotective. However, the role of increased NAAG is not clear. We used a middle cerebral artery occlusion model in rats to investigate the neuroprotective effect of NAAG via its action as a metabotropic glutamate (mGlu) receptor agonist. Rats received intracerebral injections of NAAG (1, 2, or 4 micromol), or a co-injection of NAAG (2 micromol) and the non-selective mGlu receptor antagonist, (R,S)-alpha-methyl-4-carboxyphenylglycine, (MCPG, 2 micromol). Immediately after the treatment, the animals received 2 h of middle cerebral artery occlusion followed by 22 h of reperfusion. Treatment with 1 or 2 micromol of NAAG significantly reduced total infarct volume. Treatment with MCPG partially attenuated the neuroprotective effect of NAAG, indicating that the protective effect of NAAG against ischemic injury may be in part mediated via activation of mGlu receptors.

Animals↗

PubMed2000

Striatal extracts promote the survival and phenotypic expression of rat fetal dopaminergic neurons in vitro.

To begin to identify novel protein(s) that acts on nigral dopaminergic (DA) neurons, we characterized trophic effects of DA-depleted striatum on survival of fetal DA neurons in the present study. Treatment of ventral mesencephalic cultures with the striatal extracts delayed DA cell death in a dose-dependent manner. This effect was partially dependent on brain-derived neurotrophic factor (BDNF), but not glial cell line-derived neurotrophic factor (GDNF), present in the extracts. Furthermore, we addressed the hypothesis that the striatum-derived substances can elicit DA phenotypic expression of striatal cells in cultures. The striatal extract was found to be able to induce expression of tyrosine hydroxylase in cultured striatal cells in the presence of dopamine. These data suggest that denervation of the striatum resulted in production of neurotrophic factors, including BDNF and as-yet-unidentified trophic substances, which may be responsible for the increased survival and DA phenotype expression in DA neurons.

Animals↗

PubMed2000

Differential expression of mRNAs of GDNF family in the striatum following 6-OHDA-induced lesion.

Changes of mRNA levels of GDNF and its recently discovered congeners persephin, neurturin, artemin in the striatum of lesioned side following 6-hydroxydopamine (6-OHDA) lesion in rodents were investigated with semi-quantitative RT-PCR. Two weeks after the lesions were made, mRNA levels of GDNF family members, except for neurturin, were significantly increased in the striatum on the side ipsilateral to the lesion compared with equivalent tissue of sham control. This increase reached a maximal level 5-7 weeks post-lesion. The marked increase of BDNF mRNA expression was also observed in the ipsilateral striatum with similar time course. These findings suggest that 6-OHDA-induced lesions can change gene expression in denervated target tissue, and that mRNA levels of GDNF family members in striatal cells may be modulated by afferent dopaminergic input in a slow-rising and long-lasting fashion.

Animals↗

PubMed2000

High-performance liquid chromatography with on-line post-column immunoreaction detection of digoxin and its metabolites based on fluorescence energy transfer in the far-red spectral region.

The combination of immunoassays with separation techniques such as chromatography can result in enhanced selectivity and sensitivity. This paper describes an on-line chromatography with immunochemical post-column fluorescence energy transfer detection for digoxin and its metabolites. R-phycoerythrin (PE) was used as the donor and an indodicarbocyanine dye (Cy5) as the acceptor label. These labels allow the detection in the far-red spectral region, which is more selective for biological samples. Hence, digoxin was labeled with PE using the activated digoxigenin-NHS-ester and monoclonal anti-digoxin antibody was labeled with Cy5. Digoxin and its metabolites was injected into the HPLC system followed by post-column injection of R-phycoerythrin labeled digoxin and by Cy5 labeled anti-digoxin antibody. Incubation time was provided using an open tubular reactor coil at room temperature. The detection was performed by measurement of the sensitized emission of Cy5 at 670 nm due to fluorescence energy transfer from PE labeled with digoxin. The system was optimized with regard to the concentrations of the used post-column reagents as well as incubation time and temperature. The dynamic range of digoxin spiked in 0.01 M phosphate buffer (pH 7.4) was 0.05 to 10 ng/ml with a correlation coefficient of 0.989. The limit of detection was 33 pg/ml. The precision of two controls, 0.4 and 4 ng/ml, was found to be 2.2 and 8.7% RSD, respectively, accuracy was 10.7 and 20.3% (n=6 in each case).

Antibodies↗