[Study on the clinical significance and correlation of arginase-1 and inducible nitric oxide synthase expression in hepatocellular carcinoma].

Objective: To investigate the clinical significance and correlation of arginase 1 (Arg-1) and inducible nitric oxide synthase (iNOS) expression in hepatocellular carcinoma (HCC). Methods: The expression of Arg-1and iNOS in 146 cases of hepatocellular carcinoma tissues and corresponding adjacent tissues was detected by immunohistochemistry. The clinicopathological characteristics and the correlation between the expressions and prognosis were determined by chi square test, Spearman's rank correlation, Kaplan-Meier survival analysis and Cox regression analysis. Results: The positive rates of Arg-1 and iNOS were 18.7% (23/123) and 37.0% (54/146), respectively, which was significantly lower than the adjacent tissues [100%(146/146) and 93.8% (137/146)] and the difference was statistically significant (χ (2) = 212.521, P < 0.01, χ (2) = 104.276, P < 0.01). There was a positive correlation between the both expression (r = 0.331, P < 0.01). Arg-1 low expression was correlated with preoperative serum alpha-fetoprotein (AFP) level, tumor size, differentiation degree, histological types and Edmondson's grade. iNOS low expression was correlated with the differentiation degree and Edmondson's grade (P < 0.05). Kaplan Meier survival analysis showed that in patients with recurrence-free survival (RFs), Arg-1 (+) group > Arg-1 (-) group and Arg-1 (+) iNOS (+) group > Arg-1 (+) iNOS (-) group > Arg-1 (-) iNOS (-) group (P < 0.05). Cox multivariate analysis showed that age, tumor size, Edmondson's grade, vascular tumor emboli were significantly correlated with RFs (P < 0.05). Conclusion: There is a positive correlation between Arg-1 and iNOS expressions in HCC, and both may reflect the HCC malignant degree. The reduced/absent expression of both may participate in the occurrence and development of HCC. The combined detection of Arg-1 and iNOS on HCC may have certain significance for the judgment of differentiation degree and prognosis.

Dermoscopy and VISIA imager evaluations of non-insulated microneedle radiofrequency versus fractional CO2 laser treatments of striae distensae.

BACKGROUNDS: Striae distensae (SD) has a known psychological impact due to the resulting cosmetic disfigurement. Many treatment modalities have been used over the years, but no standard interventions or evaluation methods have been proposed to date. OBJECTIVE: We compared the efficacy and safety of non-insulated microneedle radiofrequency (NIMRF) and fractional CO2 laser treatments of SD by objective measurements with dermoscopy and VISIA. METHODS: Fourteen females with severe SD were enrolled. These subjects had been treated three sessions of NIMRF and fractional CO2 laser for the right and left abdomen, respectively. Dermoscopy and VISIA imaging data, and photographs were collected at baseline and 2 months after the last treatment session. The global aesthetic improvement scale (GIAS) was scored by patients, and blinded investigators, pain score and satisfaction score were also documented. Any side effects were recorded. RESULTS: Ten patients completed the study. The GIAS from investigators and patients showed an overall improvement but without a significant difference (P = 0.18, P = 0.17, respectively). The decreased width measured by dermoscopy was between 5% and 32% (right side) and 6-31% (left side). There was no significant difference between both sides in either the per-protocol or intention to treat analyses (P = 0.149, P = 0.161, respectively). The mean pain score was 5.35 and 2.35 on the right side and left side, respectively, which was significant (P = 0.0016). Post-inflammatory hyperpigmentation (PIH) manifested in six patients on their left sides and four patients on their right sides. In most cases, this had resolved by the 3-month follow-up. CONCLUSION: Non-insulated microneedle radiofrequency and fractional CO2 laser are both effective and safe treatment options for SD. PIH is a possible side effect but is more likely with fractional CO2 laser treatment. However, it clears up in most cases. Dermoscopy and VISIA are both convenient, digitalized methods of tracking subtle changes and monitoring the efficacy of SD treatments.

[Clinical application value of combined detection of serum miR-378 and miR-21 in gastric cancer].

Objective: To investigate the clinical value of combined detection of serum miR-378 and miR-21 in gastric cancer (GC). Methods: Eighty-seven patients with GC and 78 patients with colorectal cancer(CRC) from National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences were selected, 83 individuals undergoing healthy physical examination were selected as the healthy controls. The levels of serum miR-378 and miR-21 were detected by quantitative real-time PCR (RT-qPCR) (result data were transformed as log2 for analysis). Results: Relative expression levels of miR-378 in the serum were -1.24, -3.25 and -2.73 in healthy controls, GC and CRC patients, respectively. Compared with the healthy controls, the levels of serum miR-378 were significantly decreased in GC and CRC patients (both P<0.05). Relative expression levels of miR-21 in the serum were 0.11, 2.34 and 2.47 in healthy controls, GC and CRC patients, respectively. Compared with the healthy controls, the levels of serum miR-21 were significantly up-regulated in GC and CRC patients (both P<0.05). Moreover, the serum level of miR-378 in GC patients was inversely associated with tumor clinical stage (P<0.05). However, the level of miR-21 showed no significant differences among patients with different clinical and pathological characteristics (all P>0.05). The area under the receiver operating characteristic curve (AUC), sensitivity and specificity of miRNA-378 to diagnose GC was 0.770, 82.0% and 66.0%, respectively, and were 0.900, 85.0%, and 88.0% of miR-21, respectively. The AUC, sensitivity and specificity of combined detection of serum miR-378 and miR-21 to diagnose GC were 0.930, 92.0% and 87.0%, respectively, while the AUC of combined detection of serum CEA and CA-199 was 0.767, the AUC of combined all of the four factors was 0.946. Conclusion: The combined detection of serum miR-378 and miR-21 have a certain effect on diagnosis of GC.

Experimental study on co-culturing adipose-derived stem cells with osteoblasts under different conditions.

OBJECTIVE: To observe whether adipose-derived stem cells (ADSCS), co-cultured with osteoblasts, can differentiate into osteoblasts and, if so, to study the best-induced conditions, with an ultimate goal of repairing bone defects. MATERIALS AND METHODS: Adipose-derived stem cells and osteoblasts were isolated from New Zealand white rabbits, and co-cultured in media with either 5% or 10% fetal bovine serum, for up to 4 weeks. The morphology of collected cells was examined under a microscope, and histological staining with alkaline phosphatase and alizarin red was carried out after induction for 1, 2, 3 and 4 weeks. Osteogenesis identification, including mRNA expression of type I collagen and osteocalcin, and alkaline phosphatase, was also performed using RT-PCR. RESULTS: After 7 days of co-culture, some adipose-derived stem cells became round in both groups. After 14 days of co-culture, adipose-derived stem cells were found highly-differentiated, and stained positively with alkaline phosphatase and alizarin red, similar to mature osteoblasts. The mRNA expression of type I collagen and osteocalcin increased in both groups, especially in the 10% fetal bovine serum group. CONCLUSIONS: Our findings indicate that adipose-derived stem cells co-cultured with osteoblasts can differentiate into osteoblasts when induced by a high concentration of serum culture.

Knockdown of linc-UFC1 suppresses proliferation and induces apoptosis of colorectal cancer.

Long intergenic noncoding RNAs (lincRNAs) have important roles in biological functions, molecular mechanisms and prognostic values in colorectal cancer (CRC). In this context, the roles of linc-UFC1 remain to be elucidated. In this study, linc-UFC1 was overexpressed in CRC patient tissues and positively correlated with tumor grade, N stage and M stage. Inhibition of linc-UFC1 resulted in cell proliferation inhibition and G1 cell cycle arrest, which was mediated by cyclin D1, CDK4, Rb and phosphorylated Rb. In addition, inhibition of linc-UFC1 induced cell apoptosis through the intrinsic apoptosis signaling pathway, as evidenced by the activation of caspase-9 and caspase-3. An investigation of the signaling pathway revealed that the effects on proliferation and apoptosis following linc-UFC1 knockdown were mediated by suppression of ß-catenin and activation of phosphorylated P38. Furthermore, the P38 inhibitor SB203580 could attenuate the apoptotic effect achieved by linc-UFC1 knockdown, confirming the involvement of P38 signaling in the induced apoptosis. Taken together, linc-UFC1 might have a critical role in pro-proliferation and anti-apoptosis in CRC by regulating the cell cycle, intrinsic apoptosis, and ß-catenin and P38 signaling. Thus, linc-UFC1 could be a potential therapeutic target and novel molecular biomarker for CRC.

Local expression of TAP-1 and MHC-I molecules and their relationship in condyloma acuminatum.

BACKGROUND: Condyloma acuminatum (CA), caused by human papillomavirus (HPV), is characterized by a variable clinical course that can include significant morbidity, frequent disease recurrence and occasional oncogenicity. Effective CD8+ T-cell-mediated clearance of HPV-infected cells may be defective in patients with CA, leading to recurrent disease and failure to suppress latent HPV reactivation. The pathogenesis responsible for CA and the persistence of latent HPV infection remain unknown. OBJECTIVE: To determine whether expression of transporters associated with antigen processing 1 (TAP-1) and the major histocompatibility complex class I (MHC-I) is involved in HPV immune escape. METHODS: In this present study, we compared 31 CA lesions with 30 normal prepuces by immunohistochemistry and reverse transcription PCR for their expressions of TAP-1 and MHC-I. RESULTS: Expressions of TAP-1 and MHC-I were significantly reduced in CA tissue biopsies compared with normal prepuces. There was a statistically significant positive correlation between expressions of TAP-1 and MHC-I in CA lesions. Furthermore, we found that TAP-1 mRNA was significantly reduced in CA lesions compared with those in normal prepuces. CONCLUSION: These results suggest that HPV may evade immune recognition by downregulating MHC-I cell surface expression via decreased TAP-1 levels.

Expression of endothelial nitric oxide synthase and vascular endothelial growth factor in human malignant melanoma and their relation to angiogenesis.

BACKGROUND: Angiogenesis is the major and key factor for growth and invasion of tumours, including malignant melanoma (MM), but the factors that contribute to tumour angiogenesis are still unclear. OBJECTIVE: To study expression of endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor (VEGF) in human MM and their relation to angiogenesis. To investigate the correlation between eNOS and VEGF and the role of nitric oxide (NO) generated by eNOS in the process of mediating angiogenesis by VEGF. METHODS: Tissue sections from 31 patients with MM were examined using immunohistochemistry and morphological quantitative analysis for protein expression of eNOS and VEGF. Microvessel density (MVD) was counted in endothelial cells in immunostained by anti-FVIII:RAg antibody. RESULTS: Positive eNOS and VEGF immunostaining were observed in 77.4% and 83.9% of MM lesions, respectively, whereas pigmented naevi never expressed eNOS and VEGF. A positive correlation between eNOS and VEGF in MM was observed. Expression of eNOS and VEGF was positively correlated with MVD expression in MM, and MVD expression in MM was stronger than in pigmented naevi. Expression of eNOS and VEGF was not correlated with lymph node metastasis. CONCLUSIONS. On the basis of the current data showing that malignant melanocytic tumours displayed strong VEGF and eNOS expression, whereas benign melanocytic proliferations showed no immunoreactivity for VEGF and eNOS, such expression may be used as a discriminating factor to distinguish malignant melanoma from pigmented naevi. Expression of eNOS and VEGF may contribute to angiogenesis of MM, eNOS probably plays an important role in mediating VEGF-induced angiogenesis.

Endogenous production of nitric oxide contributes to proliferation effect of vascular endothelial growth factor-induced malignant melanoma cell.

The objectives of this study were to observe the effect of overexpression of vascular endothelial growth factor (VEGF) on the proliferation of the malignant melanoma (MM) cell line A375, and to study the role of nitric oxide (NO) in this process and the mechanism of VEGF induced-A375 cell proliferation. The VEGF(165) cDNA was transfected into A375 cells by electroporation. VEGF mRNA and protein in A375 cells were detected by RT-PCR and ELISA. The proliferation of A375 cells was assessed by cell counting and MTT assay. Protein expression of iNOS, eNOS and nNOS was detected by Western blotting. NO production in A375 cell supernatant was measured by the nitrate reductase method. VEGF mRNA in A375 cells was significantly increased 72 h and 96 h after transfection of VEGF(165) cDNA, as were VEGF protein, NO and iNOS levels. However, protein expression of eNOS and nNOS was not detected in either transfected or untransfected cells. Proliferation of A375 cells transfected with VEGF(165) cDNA was enhanced. The nitric oxide synthase inhibitor l-NAME could dose-dependently inhibit the proliferation of A375 cells evoked by VEGF. These results indicate that VEGF enhances the expression of iNOS in A375 cells and results in an increase in NO formation, which may be important in the process of VEGF-induced proliferation of A375 cells.

RETRACTED: Isolation, characterization and expression of a gene from Brassica napus encoding a LIM-domain protein.

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Inhibiting the growth of malignant melanoma by blocking the expression of vascular endothelial growth factor using an RNA interference approach.

BACKGROUND: Vascular endothelial growth factor (VEGF) is overexpressed in malignant melanoma (MM). OBJECTIVES: To develop an RNA interference approach that specifically targets VEGF by constructing a eukaryotic expression plasmid containing short interfering RNA (siRNA), and to evaluate the effects of this vector on the proliferation and apoptosis of MM in vitro and in vivo. METHODS: pU-VEGF-siRNA plasmid was transfected into MM cell line A375 and colorectal carcinoma cell line Lovo by electroporation. Expression of VEGF mRNA and protein in A375 and Lovo cells after gene transfer was detected by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Proliferation of pU-VEGF-siRNA-transfected A375 and Lovo cells and control cells was observed by cell counting through the microscope. The proliferation of human umbilical vein endothelial cells (ECV-304) cultured in medium containing supernatants of transfected and control A375 cells was measured by the cell counting method. Flow cytometry (FCM) was used to analyse the apoptosis of transfected and control groups. In a mouse model, tumorigenicity and tumour growth of transfected cells were studied in vivo. VEGF expression and microvessel density (MVD) in tumour tissue were measured by immunohistochemistry. Apoptosis in tumours was detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling. RESULTS: Expression of VEGF mRNA and protein in pU-VEGF-siRNA-transfected A375 and Lovo cells was significantly decreased on days 3, 10, 17 and 24 post-transfection, compared with controls. The greatest suppression occurred on days 3 and 10 post-transfection. The proliferation of transfected A375 cells and ECV-304 cocultured with supernatants of transfected A375 cells was inhibited. FCM analysis showed that a hypodiploidy peak was found only in A375 cells transfected by pU-VEGF-siRNA. After subcutaneous inoculation with pU-VEGF-siRNA-transfected A375 cells, tumour growth in mice was inhibited, VEGF expression and MVD were decreased, and tumour apoptosis was increased significantly, in comparison with mice inoculated with untransfected A375 cells. CONCLUSIONS: The delivery of siRNA directed against VEGF was shown not only to give efficient and specific downregulation of the expression of VEGF, inhibit proliferation of A375 and ECV-304 cells and induce apoptosis of A375 cells in vitro, but also to suppress growth of MM in vivo. These results suggest that a strategy based on siRNA targeting of VEGF may build the foundation to the clinical management of MM.

Determination of DNA with cetyltrimethylammonium bromide by the measurement of Resonance Light Scattering.

A simple assay of DNA was developed based on the measurements of enhanced signals of Resonance Light Scattering (RLS) of cetyltrimethylammonium bromide (CTMAB) by DNA. The enhanced RLS signals, measured by simultaneously scanning the excitation and emission monochromators of a common spectrofluorometer with lambda ex = lambda em, was optimized for the DNA assay with CTMAB. On the conditions of pH 2.21 and ionic strength 0.002, the enhanced RLS intensity at 470.0 nm, delta I, was found to be proportional to the concentration of DNA in the range 0-2.5 micrograms/ml if 1.5 x 10(-5) M CTMAB was used. Limits of determination for calf thymus DNA and fish sperm DNA were 4.9 ng/ml and 9.2 ng/ml, respectively. Synthetic samples were determined with the recovery ratio ranging from 93.2% to 105.1%, and the RSD is lower than 2.7%.

Anodization in oligo(ethylene glycol) as an initial derivatization tool for preparing glassy carbon electrodes covalently modified with amino compounds: effective access to a 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-modified glassy carbon electrode.

Anodization in HO(CH2CH2O)nH (1a, n=2; 1b, n=3; 1c, n=4) as an initial derivatization tool for preparing glassy carbon (GC) electrodes covalently modified with amino compounds was explored. As an amino compound to be immobilized, 4-amino-2,2,6,6-tetramethylpiperidinyl-1-oxyl (4-amino-TEMPO) was selected. When GC electrodes anodized at 2.0 V vs. Ag wire coated with AgCl in 1 containing RCH2CH2SO3Na (2a, R=H; 2b, R=OH) were treated with a N,N-dimethylformamide (DMF) or CH2Cl2 solution of 4-amino-TEMPO and 1,3-dicyclohexylcarbodiimide (DCC), TEMPO-modified GC electrodes were afforded. Coverage (gammaTEMPO) of the electrode surfaces by TEMPO was estimated by cyclic voltammetry in CH3CN containing NaClO4. A TEMPO-modified GC electrode with the best gammaTEMPO (1.36 x 10(-10) mol/cm2) was obtained by anodization in 1b containing 2a at the expense of 3.0 C followed by amidization in DMF for 7 d. On cyclic voltammetry, the TEMPO-modified GC electrode showed good and stable electrocatalytic ability for oxidation of allyl alcohol in the presence of 2,6-lutidine.

Total internal reflected resonance light scattering determination of chlortetracycline in body fluid with the complex cation of chlortetracycline-europium-trioctyl phosphine oxide at the water/tetrachloromethane interface.

A highly selective method of chlortetracycline (CTC) is proposed on the basis of the measurements of total internal reflected resonance light scattering (TMR-RLS) at water/tetrachloromethane (H20/CCl4) interfaces. In the pH range of 7.54-8.14, the interaction of the binary complex of Eu(III)/CTC in the presence of trioctyl phosphine oxide (TOPO) occurs at the H20/CCl4 interface, resulting in greatly enhanced TIR-RLS signals with the maximum peak located at 340 nm. The enhanced TIR-RLS intensity is in proportion to the CTC concentration in the range 0.98 to approximately 20.0 x 10(-7) mol/L. The limit of detection is 9.8 x 10(-9) mol/L. Synthetic samples and body fluid samples including human urine, human serum, and fresh milk were determined with the recovery of 95.4-106.4% and RSD of 2.9-3.9%.

[Detection of serum Lp(a) level of coronary heart disease and its clinical significance].

OBJECTIVE: To study the association of human serum Lp(a) level and coronary heart diseases. METHODS: Objects examined were conposed of 2 groups: CHD (39 cases) and healthy controls (52 cases). Lp (a), TC, HDL-C, TG, apoB of two groups were determined and the results were done with statistic analysis. RESULTS: The mean serum Lp(a) concentrations (mg.L-1) in coronary heart disease group were shown higher significantly than that in the control group (P < 0.01). However, there were no significant correlation between the mean serum Lp(a) and the mean serum TC, HDL-C, TG, spoAI and aopB.(P > 0.05). CONCLUSIONS: Serum Lp(a) level is closely related to the occurrence of coronary heart disease. Lp(a) is a single risk factor for coronary heart disease. Detecting the determination of serum Lp(a) is extremely valuable to the clinical prediction and diagnosis of CHD.

[Impact of AFP promoter on the expressions of GFP in tumor cells].

OBJECTIVE: To study the impact of AFP 5'flanking promoter (enhancer) on the expression of GFP in hepatocarcinoma cell. METHODS: Green Fluorescent Protein (GFP) reporter gene expression plasmid pcDNA3-GFP-AFP-w under the direction of AFP 5' flanking promoter (enhancer) was constructed by recombinant DNA technology and confirmed by restriction analyses. pcDNA3-GFP-AFP-w, pcDNA3-GFP and pcDNA3 were transfected into Hela and Bel7402 cells by lipofectin and selected by G418 respectively, after amplification of the positive cell clones, expression of GFP was detected by Western blotting and quantitatively analysed by GEL Doc 2000 digital image systems. RESULTS: The expression of GFP was lower in Bel-GFP-AFP-w than in Bel-GFP but was significantly higher than in Hela-GFP-AFP-w. CONCLUSION: GFP reporter gene plasmid pcDNA3-GFP-AFP-w under the direction of the 3.1 kb AFP 5'flanking promoter (enhancer) can be expressed in HCC Bel7402 cell definitely and specifically.

A spectrophotometric study on the interaction of neutral red with double-stranded DNA in large excess.

With the measurement of molecular absorption, the interaction of neutral red (NR) with double-stranded DNA in large excess was investigated. It was found that the interaction of NR, existing in the acidic state (HNR) at pH 4.56, with double-stranded structure DNA displays different spectral features depending on the molar ratio of HNR/DNA, R. If R>1.33, the binding process is characterized by a binding constant at the 10(6) level with each nucleotide residue of double-stranded DNA binding one HNR molecule. If R<0.67, the binding constant is reduced to the 10(4) level, and the binding number for each nucleotide residue of double-stranded DNA to HNR is less than one.

Determination of proteins by their enhancement of resonance light scattering by fuchsine acid.

Based on the measurement of the enhancement of resonance light scattering (RLS) of fuchsine acid (FSA) by proteins, a novel sensitive assay of proteins in body fluid samples has been developed. Proteins, including bovine serum albumin (BSA), human serum albumin (HSA), pepsin (Pep), alpha-chymotrypsin (Chy), lysozyme (Lys), and cellulase (Cel), can bind to fuchsine acid (FSA), resulting in enhanced RLS signals at 277.0 nm. Linear relationships between the enhanced RLS intensity and the protein concentration were measured at different concentration of FSA, and the limits of detection for BSA, HSA, and Lys were found to lie in the nanogram range.

Biodegradation of 2,4,6-trichlorophenol in the presence of primary substrate by immobilized pure culture bacteria.

In this study, pure strains that are capable of utilizing 2,4,6-trichlorophenol have been isolated from the mixed culture grown on substrates containing chlorophenolic compounds. Studies have been carried out on the capability of these isolated pure strains in suspended and immobilized forms to decompose 2,4,6-trichlorophenol. Additionally, the influence of primary substrates (e.g., phenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol) on the decomposition of 2,4,6-trichlorophenol by the isolated pure strains grown in immobilized form is also investigated. The results are: Through bacterial isolation and identification, three pure strains have been obtained: Pseudomonas spp. strain 01, Pseudomonas spp. strain 02 and Agrobacterium spp. Whether in suspended or immobilized forms, all strains have poor removal efficiencies of 2,4,6-trichlorophenol. However, addition of 200 mg/l phenol will enable the immobilized Pseudomonas spp. strain 01, and Pseudomonas spp. strain 02 to achieve 65% and 48% removal of 2,4,6-trichlorophenol, respectively. Addition of phenol will assist the immobilized Pseudomonas spp. strain 02 in achieving removal of 2,4,6-trichlorophenol but the removal efficiency is not good if the phenol concentration is too low. The optimum phenol concentration should be between 200 and 400 mg/l.

Interactions of Janus Green B with double stranded DNA and the determination of DNA based on the measurement of enhanced resonance light scattering.

A novel assay of DNA with a sensitivity at the nanogram level is proposed based on the measurement of enhanced resonance light scattering (RLS) signals resulting from the interaction of Janus Green B (JGB) with DNA. At pH 6.37 and ionic strength < 0.20, the RLS signals of JGB were greatly enhanced by DNA in the region of 300-650 nm characterized by three peaks at 416.0, 452.0 and 469.2 nm. The binding properties were examined using a Scatchard plot based on the measurement of the enhanced RLS data at 416.0 nm at a high JGB: DNA molar ratio (R > 2.22), and an aggregation mechanism of JGB in the presence of DNA at the nanogram level is proposed. Linear relationships can be established between the enhanced RLS intensity and DNA concentration in the range 0-3.5 micrograms ml-1 for both calf thymus DNA (ctDNA) and fish sperm DNA (fsDNA) if 2.0 x 10(-5) M JGB is employed. The limits of determination were 8.7 ng ml-1 for ctDNA and 9.9 ng ml-1 for fsDNA, respectively. Synthetic samples were analysed satisfactorily.

Spectrophotometric study on the supramolecular interactions of nile blue sulphate with nucleic acids.

The supramolecular interaction of nile blue sulphate (NBS) with nucleic acids was studied by investigating the characteristics of the interaction absorption spectra on the basis of the drug binding process in organic system in which small amount of drug interacting with large amount of biological macromolecules involves, and an accordingly binding model for organic dyes with large amount of macromolecules was established. At pH 7.40 and ionic strength 0.004, the H-aggregation of NBS occurs with increasing NBS concentration. The NBS aggregates can be bound to both calf thymus DNA and fish sperm DNA by the ratio of each nucleotide residue with a molecule of NBS if the concentration of DNAs is more than 15-fold excessive. The corresponding binding constant for the interaction of NBS with DNAs is about 10(3) order, with which thermodynamic parameters for the interactions, such as the change of free energy, enthalpy and entropy at 25 degrees C, were calculated. It was found that the binding of NBS with thermally denatured DNA is similar to that with native yeast RNA, which indicates H-aggregation of NBS can be encouraged by single stranded nucleic acids.