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K Li

Publications and source records attributed to K Li.

At least 181 records · Page 10Linked to original sources
PubMed1999

Characterization of the molecular species of phosphatidylethanolamine from kidney of the fresh water snail Lymneae stagnalis by mass spectrometry.

The structural analysis of sixteen molecular species of diacyl glycerophosphoethanolamine from fresh water snail Lymneae stagnalis kidney using chromatography and mass spectrometry is described in this paper. 1-eicosadienoyl-2-eicosatetraenoyl-sn-glycero-3-phosphoethanolamine (PE 20:2-20:4), 1-eicosapentaenoyl-2-eicosadienoyl-sn-glycero-3-phosphoethanolamine (PE 20:5-20:2) and 1-eicosatrienoyl-2-eicosatetraenoyl-sn-glycero-3-phosphoethanolamine (PE 20:3-20:4) as well as 1-octadecanoyl-2-eicosatetraenoyl-sn-glycero-3-phosphoethanolamine (PE 18:0-20:4), 1-ocetadecenoyl-2-eicosatetraenoyl-sn-glycero-3-phosphoethanolamine (PE 18:1-20:4) and 1-octadecanoyl-2-eicosapentaneoyl-sn-glycero-3-phosphoethanolamine (PE 18:0-20:5) were found as the major molecular species, and the first three were tentatively identified as the novel species present in this biological material. The presence of a relatively high content of 1,2-dieicosenoyl-sn-glycero-3-phosphoethanolamine species (approximately 27% of total species) as well as the absence of 22-carbon fatty acid containing and plasmalogen PE molecular species are remarkable in healthy Lymneae stagnalis kidney. Copyright 1999 John Wiley & Sons, Ltd.

Journal Article↗
PubMed1999

Radon, tobacco-specific nitrosamine and mutagenesis in mammalian cells.

The mutagenicity of 4-methylnitrosamine-1-3-pyridyl-1-butanone (NNK), either alone or in combination with low dose alpha particle irradiation, was examined using the human-hamster hybrid (A(L)) cell assay. NNK induced a dose-dependent toxicity in A(L) cells. In combination with a 25 cGy dose of alpha particles, the induced survival fraction fell within the statistical range of the calculated values assuming an additive interaction of the two agents. In addition, NNK is mutagenic in A(L) cells at the CD59 locus. Furthermore, a low dose of NNK, when combined with radon alpha particles, resulted in a combined mutagenic effect in A(L) cells that was consistent with an additive model but less than additive at higher NNK concentrations. The majority of NNK induced CD59(-) mutants (77.6%) lost at least one additional marker in addition to the CD59 which encodes the cell surface antigen. When combined with alpha particles, the proportion of mutants with additional marker loss increased with increasing dose of NNK. Our study further confirms that NNK is mutagenic in mammalian cells, induces mostly deletions, and provides an in vitro assessment of the combined genotoxic effects of NNK and alpha particles at low environmentally relevant doses. This finding should be helpful in understanding the molecular mechanism of the mutagenic process as a result of multi-agent interaction.

Alpha Particles↗
PubMed1999

Association of Nafion with Polypyrrole Nanoparticles in a Hydrophilic Polymer Network: Effects on Proton Transport.

Proton-conducting polymer composites containing perfluorosulfonic polymer (Nafion) and polypyrrole (PPy) nanoparticles in a polyacrylamide network, P(AAM-MBAM), were synthesized as proton-conducting electrolytes. An investigation into the assembling of Nafion polymer molecules as well as the colloidal PPy-Nafion complexes in the P(AAM-MBAM) network was carried out on the basis of DSC and XRD analysis. It was found that the proton conductivity of the composites was largely affected by the occurrence of the free volume between the P(AAM-MBAM) network and Nafion polymer as well as the concentration of the PPy-Nafion complexes in the composites according to the measurements of the electrical resistance and the frequency-dependent impedance. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Fed-batch fermentor synthesis of 3-dehydroshikimic acid using recombinant Escherichia coli.

3-Dehydroshikimic acid (DHS), in addition to being a potent antioxidant, is the key hydroaromatic intermediate in the biocatalytic conversion of glucose into aromatic bioproducts and a variety of industrial chemicals. Microbial synthesis of DHS, like other intermediates in the common pathway of aromatic amino acid biosynthesis, has previously been examined only under shake flask conditions. In this account, synthesis of DHS using recombinant Escherichia coli constructs is examined in a fed-batch fermentor where glucose availability, oxygenation levels, and solution pH are controlled. DHS yields and titers are also determined by the activity of 3-deoxy-D-arabino-heptulosonic acid 7-phosphate (DAHP) synthase. This enzyme's expression levels, sensitivity to feedback inhibition, and the availability of its substrates, phosphoenolpyruvate (PEP) and D-erythrose 4-phosphate (E4P), dictate its in vivo activity. By combining fed-batch fermentor control with amplified expression of a feedback-insensitive isozyme of DAHP synthase and amplified expression of transketolase, DHS titers of 69 g/L were synthesized in 30% yield (mol/mol) from D-glucose. Significant concentrations of 3-dehydroquinic acid (6.8 g/L) and gallic acid (6.6 g/L) were synthesized in addition to DHS. The pronounced impact of transketolase overexpression, which increases E4P availability, on DHS titers and yields indicates that PEP availability is not a limiting factor under the fed-batch fermentor conditions employed.

3-Deoxy-7-Phosphoheptulonate Synthase↗
PubMed1999

Cytokine regulation of chronic cardiac allograft rejection: evidence against a role for Th1 in the disease process.

BACKGROUND: Transient depletion of CD4+ T cells in cardiac allograft recipients prolongs allograft survival; however, grafts exhibit signs of chronic rejection characterized by collagen deposition and neointima development. Although it is believed that Th1 cells promote acute graft rejection, the role of these cells in chronic rejection remains unclear. Hence, our study evaluated whether Th1 cells are associated with the development of chronic cardiac allograft rejection. METHODS: Splenocytes obtained from C57BL/6 recipients bearing BALB/c hearts with signs of chronic rejection were adoptively transferred into C57BL/6 SCID cardiac allograft recipients. As a measure of Th1 function, interferon-y production was determined after restimulation of recipient splenocytes with donor alloantigens. RESULTS: Transfer of splenocytes in SCID allograft recipients resulted in accelerated chronic rejection in the majority of mice. Characterization of these cells before transfer revealed hyporesponsive Th1 function. However, donor-specific proliferative responses and precursor interleukin-2 producing helper and cytotoxic T lymphocyte frequencies were comparable to that of naive splenocytes. Further, splenocytes obtained from SCID recipients with advanced signs of chronic rejection remained deficient in Th1 function, suggesting that Th1 are not involved in this disease process. This possibility was further supported by the development of chronic rejection in IL-12 knockout recipients. Finally, when splenocytes used for adoptive transfer retained Th1 function, transfer of these cells into SCID recipients resulted in acute allograft rejection. CONCLUSIONS: We have established a model in which the mediators of chronic rejection may be further explored. In this system, the absence rather than the presence of donor-reactive Th1 is associated with chronic rejection. These data indicate that Th1-independent effector mechanisms are responsible for chronic rejection in this model.

Adjuvants, Immunologic↗
PubMed1999

Interleukin-12 (IL-12)-driven alloimmune responses in vitro and in vivo: requirement for beta1 subunit of the IL-12 receptor.

BACKGROUND: Interleukin-12 (IL-12) mediates its biologic activities via binding high-affinity receptors on T and natural killer cells. Although emphasis has been placed on the requirement for IL-12Rbeta2 in IL-12 bioactivity, the role of IL-12Rbeta1 is less well defined. The current study evaluated the effects of exogenous IL-12 on alloantigen-specific immune responses and determined the requirement for IL-12Rbeta1 in IL-12-mediated alloimmunity. METHODS: The mouse heterotopic cardiac transplant model was employed to evaluate the effects of IL-12 on alloantigen-specific immune responses in vivo. In addition, IFN-gamma production in mixed lymphocyte cultures (MLC) supplemented with IL-12 was measured to assess the effects of IL-12 on Th1 function in vitro. Mice deficient in IL-12Rbeta1 (IL-12Rbeta1-/-) were used to determine the requirement for this receptor component in IL-12-driven alloimmune responses. RESULTS: Addition of IL-12 to MLC consisting of wild-type splenocytes enhanced alloantigen-specific proliferative responses and Th1 development. In contrast, IL-12 did not alter these in vitro immune parameters in IL-12Rbeta1-/- MLC. Treatment of wild-type cardiac allograft recipients with IL-12 resulted in high concentrations of serum interferon-gamma (IFN-gamma) and a 10-fold increase in IFN-gamma production by recipient splenocytes after restimulation in vitro. However, this fulminate Th1 response did not accelerate allograft rejection. Importantly, IL-12 had no effect on serum IFN-gamma or in vivo priming of Thl in IL-12Rbeta1-/- recipients. Finally, administration of IL-12 to WT allograft recipients resulted in a bimodal alloantibody response: antibody production was suppressed at high doses of IL-12, and enhanced at lower doses. CONCLUSIONS: IL-12 markedly enhances alloantigen-specific immune function; however, these exaggerated Th1-driven responses do not culminate in accelerated allograft rejection. Further, these data indicate that IL-12Rbeta1 is essential for the enhancement of both in vitro and in vivo alloimmune responses by exogenous IL-12.

Animals↗
PubMed1999

High-frequency homologous genetic recombination of an arterivirus, lactate dehydrogenase-elevating virus, in mice and evolution of neuropathogenic variants.

On the basis of genome nucleotide differences between a nonneuropathogenic and a neuropathogenic lactate dehydrogenase-elevating virus (LDV) quasispecies (LDV-P and LDV-C, respectively), we have designed sets of primers for polymerase chain reaction (PCR) amplification that can detect recombinants between them in a 1276-nt-long segment ranging from ORF 5 to ORF 7. Mice were infected with large amounts of both LDVs and bled at various times postinfection (p.i.). RNA was extracted from plasma samples and reverse transcribed and the first-strand products were PCR amplified with four sets of sense and antisense primers that discriminate between parental (P/P and C/C) and recombinant (P/C and C/P) genomic segments. Both P/C and C/P recombinants were detected in plasma from six different mice at 1 day p.i. No recombinant products were generated with in vitro mixtures of LDV-P and LDV-C. End-point dilution experiments indicated that the generation of P/C and C/P recombinants varied between mice but that in some mice the frequency of recombination in the 1276-nt-long genome segment was as high as 5%. Sequence analyses of clones of some recombinants indicated that recombination had occurred at 26- to 43-nt-long stretches of homology between the LDV-P and the LDV-C genomes. Sequence analyses of the 3157-nt-long 3' end of the genomes of the neuropathogenic LDV-v and of a newly discovered nonneuropathogenic quasispecies, LDV-vx, showed that LDV-v is a natural recombinant of LDV-vx that has specifically acquired by a double recombination about 400 nt of the 5' end of ORF 5 of the neuropathogenic LDV-C and thereby the unique properties of LDV-C, neuropathogenicity and high sensitivity to antibody neutralization. In dual infections of mice with LDV-P and LDV-C all genetic recombinants, like the LDV-C parent itself, had been lost by 7 days p.i., and only LDV-P persisted. The results further support the view that LDV-P and LDV-vx have evolved to a highly stable relationship with their host, the mouse.

Animals↗
PubMed1999

Astrocytic demise precedes delayed neuronal death in focal ischemic rat brain.

Active neuronal-glial interaction is important in the maintenance of brain homeostasis and is vital for neuronal survival following brain injury. The time course of post-ischemic astroglial dysfunction and neuronal death was studied in the spontaneously hypertensive rat (SHR) brain following permanent middle cerebral artery occlusion (MCAO). In situ hybridization with 35S-labeled riboprobes for GFAP and GLUT3 was used to monitor mRNA expression in glia and neurons. Astrocytic proteins GFAP, vimentin, S100, Glutathione-S-Transferase Yb (GST Yb) and neuronal protein TG2 were detected by immunofluorescence. Cells were co-stained with in situ end labeling (ISEL) to detect DNA fragmentation, a hallmark of cell death. GFAP mRNA expression declined rapidly in the ischemic region of the cortex and was almost absent by 12 h. Immunohistochemical studies revealed a parallel decline in the corresponding protein: a reduction in GFAP staining was apparent in the infarct after 3 h and by 24 h, there was essentially no remaining GFAP. Three other glial proteins (vimentin, S100 and GST Yb) disappeared from infarct over a similar time course. A few ISEL positive cells were observed in the infarct at 6 h, but maximal detection was not seen until 24-48 h. Most of the ISEL-positive cells were neurons, identified by co-staining with the neuronal marker TG2. Few cells expressing GFAP or other glial markers were positive at any time point. Neuronal GLUT3 mRNA declined more slowly than GFAP mRNA in the ischemic core and disappeared during the period of neuronal death. Concurrent with the loss of GFAP mRNA and protein expression in the infarct, there was a rapid rise in GFAP mRNA in the peri-infarct region of ipsilateral hemisphere and proximal region of the contralateral hemisphere. This was followed by the enhanced GFAP protein expression characteristic of reactive astrocytes, but over a significantly slower time course. These studies show that MCAO leads to a rapid decline of GFAP mRNA and glial proteins, which appears to precede the decline in neuronal mRNA and neuronal death within the infarct. Early astroglial dysfunction may play a critical role in determining the outcome of acute hypoxic-ischemic injury by compromising neuronal-glial interactions.

Animals↗
PubMed1999

Collagen-homology domain 1 deletion mutant of Shc suppresses transformation mediated by neu through a MAPK-independent pathway.

Shc proteins are implicated in coupling receptor tyrosine kinase to the mitogen-activated protein kinase (MAPK) pathway by recruiting Grb2/SOS to the plasma membrane. To better understand the role of Shc in the oncogenesis by point-mutation activated neu (p185*), we transfected a Shc mutant (ShcdeltaCHI), which lacks the Grb2 binding site Y317 by deletion of collagen-homology domain 1, into p185*-transformed NIH3T3 cells. The cellular transformation phenotypes were found to be largely suppressed by expression of ShcdeltaCH1. Although ShcdeltaCH1 still retained another Grb2 binding site (Y239/240), we did not detect its physical association with Grb2. We also found that ShcdeltaCH1 could associate with p185*; however, this association did not interfere with the endogenous Shc-p185* interaction or the Shc-Grb2 interaction. In addition, p185*-mediated MAPK and Elk activation likewise were not inhibited by ShcdeltaCH1 expression. Taken together, these data demonstrate that ShcdeltaCH1 suppresses the transformation induced by activated neu through a MAPK-independent pathway, indicating that Shc may be involved in other signal pathway(s) critical for cellular transformation in addition to the MAPK pathway.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Growth inhibition of breast cancer cells by Grb2 downregulation is correlated with inactivation of mitogen-activated protein kinase in EGFR, but not in ErbB2, cells.

Increased breast cancer growth has been associated with increased expression of epidermal growth factor receptor (EGFR) and ErbB2 receptor tyrosine kinases (RTKs). Upon activation, RTKs may transmit their oncogenic signals by binding to the growth factor receptor bound protein-2 (Grb2), which in turn binds to SOS and activates the Ras/Raf/MEK/mitogen-activated protein (MAP) kinase pathway. Grb2 is important for the transformation of fibroblasts by EGFR and ErbB2; however, whether Grb2 is also important for the proliferation of breast cancer cells expressing these RTKs is unclear. We have used liposomes to deliver nuclease-resistant antisense oligodeoxynucleotides (oligos) specific for the GRB2 mRNA to breast cancer cells. Grb2 protein downregulation could inhibit breast cancer cell growth; the degree of growth inhibition was dependent upon the activation and/or endogenous levels of the RTKs. Grb2 inhibition led to MAP kinase inactivation in EGFR, but not in ErbB2, breast cancer cells, suggesting that different pathways might be used by EGFR and ErbB2 to regulate breast cancer growth.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Monoclonal antibody-based ELISAs for part-per-billion determination of polycyclic aromatic hydrocarbons: effects of haptens and formats on sensitivity and specificity.

As a first step toward developing sensitive enzyme-linked immunosorbent assays (ELISAs) for multianalyte detection of polycyclic aromatic hydrocarbons (PAHs), haptens with different lengths of carboxylic acid spacers at various positions were derived from naphthalene, fluorene, anthracene, phenanthrene, pyrene, fluoranthene, chrysene, and benzo[a]pyrene (BaP). These haptens were coupled with bovine serum albumin (BSA) to form competitor conjugates. All of these haptens were recognized to different extents by monoclonal antibodies (MAbs) 4D5 and 10C10 originally derived by Gomes and Santella (Chem. Res. Toxicol. 1990, 3, 307-310). The most sensitive indirect ELISAs were obtained by coating wells with the least competitive conjugates. Direct ELISAs using horseradish peroxidase conjugates of pyrene and BaP were less sensitive. The MAbs bound BaP with spacers at either C1 or C6. The cross-reactivity profiles of the eight PAHs were different with each PAH-BSA conjugate used as coating antigen. The ELISA results for BaP closely correlated with those by gas chromatography (GC), but the detection limit of the ELISA was approximately 150-fold more sensitive than that of GC, with 2-600 nM spike recoveries of 80-127% from human urine and canal and tap water.

Antibodies, Monoclonal↗
PubMed1999

Analysis of 9-fluorenylmethyloxycarbonyl derivatives of catecholamines by high performance liquid chromatography, liquid chromatography/mass spectrometry and tandem mass spectrometry.

9-Fluorenylmethyloxycarbonyl (FMOC) derivatives of catecholamines, including dopamine (DA; 3,4-dihydroxyphenethylamine), norepinephrine (NE; 2-amino-1-(3,4-dihydroxyphenyl)ethanol) and epinephrine (EPI; 1-phenyl-1-hydroxy-2-methylaminopropane) as well as 3, 4-dihydroxybenzylamine (DHBA) have been analyzed using high performance liquid chromatography coupled to fluorometric detection and atmospheric pressure chemical ionization mass spectrometry at low femtomole levels. Structures of the derivatives have also been characterized by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry and electrospray/tandem mass spectrometry. Protonated molecules of FMOC-DA and FMOC-DHBA as well as [M + H - H(2)O](+) ions of FMOC-NE and FMOC-EPI appear in their conventional mass spectra, and abundant fragments characteristic of catecholamines dominated the spectra. Structurally diagnostic ions using several hundred femtomoles of the FMOC derivatives of catecholamine were observed. Collision-induced dissociation (CID) of electrospray-generated protonated molecules of FMOC-DA and FMOC-DHBA as well as [M + H - H(2)O](+) ions of FMOC-NE and FMOC-EPI produced diagnostic product ion spectra. Liquid chromatography/atmospheric pressure chemical ionization mass spectrometric analysis of the FMOC derivatives of catecholamines and DHBA should prove useful in the separation and characterization of these compounds from biological materials.

Animals↗
PubMed1999

Granulocyte colony-stimulating factor-mobilized peripheral blood stem cells in beta-thalassemia patients: kinetics of mobilization and composition of apheresis product.

beta-Thalassemias are often associated with bone marrow expansion and immunomodulation in terms of lymphocyte subsets and cytokine levels in the peripheral blood. The mobilization of peripheral blood stem cells (PBSC) by cytokines in such a background has not been reported. If achieved, the apheresis product could be used as a stem cell back-up for beta-thalassemia patients prior to bone marrow transplant. PBSC collection may also become a means for providing stem and progenitor cells for gene manipulation and therapy of this disorder. The aim of the study was to assess the administration of G-CSF in mobilizing stem and progenitor cells in these patients and to compare the kinetics of CD34+ cells and lymphocyte subsets with those of healthy PBSC donors. Results showed that the CD34+ cells were effectively mobilized by G-CSF (10-16 micrograms/day per kg) in 20 thalassemia patients and 11 healthy donors. Although no significant difference was observed in levels of daily stem cell counts between the two groups of subjects, a 1 day delay in achieving peak levels of CD34+ cells was observed in the majority of thalassemia patients. The peak increase of CD34+ cells was 21.5 +/- 6.1-fold and 30.8 +/- 7.6-fold of the basal steady-state levels in thalassemia patients and healthy donors, respectively. Similar to the situation of healthy donors, G-CSF stimulated essentially the CD34+ cells and the myeloid lineage (granulocytes, monocytes) in thalassemia patients and had a slight effect on lymphocyte subsets (T-helper, T-suppressor, NK, and B cells) and activation (CD25, HLA-DR, and CD45RO). Compositions of the apheresis products, including CD34+CD38-, CD34+CD33+ and CD34+HLA-DR- cells, were similar in the two groups of subjects. Correlation studies showed that the level of CD34+ cells in the PB is a good indicator of that in the apheresis product (r = 0.88, p < 0.001). The study has demonstrated that under close monitoring of CD34+ cell levels in PB, the mobilization by G-CSF and collection of PBSC in beta-thalassemia patients are feasible.

Adolescent↗
PubMed1999

In vitro sensitivity of artemeter in Plasmodium falciparum-infected beta-thalassaemic trait erythrocytes.

Using an age-fractionated RBC model, we investigated the in vitro sensitivity of artemether in beta-thalassaemic RBC infected with the K1 and FC27 strains of Plasmodium falciparum and, to study the role of oxidant stress in modulating the sensitivity pattern, pro-oxidant (riboflavin) and antioxidant (vitamin E) agents were added to cultures in the presence of artemether. With the FC27 strain, the artemether IC50 doses in thalassaemic samples (whole blood and fractions) were significantly higher compared to equivalent normal RBC samples (P < 0.05). However, with the K1 strain, such a significant difference was not demonstrable. The addition of vitamin E reduced the antimalarial effect of artemether in both the FC27 and K1 strains (P < 0.0001). In contrast, the addition of riboflavin resulted in a significant increase in antimalarial activity (P < 0.0001). This effect of the drug combinations was not influenced by the red cell type (P < 0.0001) and there was no interaction between red cell type and drug type (P < 0.0001). These findings show that reduced sensitivity to artemether occurs in whole blood and age-fractionated beta-thalassaemic trait RBC. It appears that the RBC redox status does not influence the sensitivity to artemether.

Animals↗
PubMed1999

Tissue-specific consequences of the anti-adenoviral immune response: implications for cardiac transplants.

The immune response to adenoviral vectors can induce inflammation and loss of transgene expression in transfected tissues. This would limit the use of adenovirus-mediated gene transfer in disease states in which long-term gene expression is required. While studying the effect of the anti-adenoviral immune response in transplantation, we found that transgene expression persisted in cardiac isografts transfected with an adenovirus encoding beta-galactosidase. Transfected grafts remained free of inflammation, despite the presence of an immune response to the vector. Thus, adenovirus-mediated gene transfer may have therapeutic value in cardiac transplantation and heart diseases. Furthermore, immunological limitations of adenoviral vectors for gene therapy are not universal for all tissue types.

Adenoviridae↗
PubMed1999

Ex vivo expansion of enriched CD34+ cells from neonatal blood in the presence of thrombopoietin, a comparison with cord blood and bone marrow.

Neonatal blood (NB) contains substantial numbers of stem and progenitor cells which decline rapidly after birth. Using a combination of cord blood (CB) and NB, we performed a successful, sibling transplant for a thalassaemia patient, leading to the proposal that NB could be used as an adjunct to CB for transplantation. This study was aimed at addressing the feasibility of expanding NB and thus minimizing the volume needed from a NB collection. In the presence of early acting cytokines interleukin-1beta (IL-1beta), IL-3, IL-6, stem cell factor (SCF), flt-3 ligand with and without thrombopoietin (Tpo), we compared the expansion capacity of CD34+ enriched cells from CB, NB and bone marrow (BM). Flow cytometry and colony-forming unit (CFU) analyses show that Tpo significantly increased the expansion of CD34+ cells from CB and NB to early and committed progenitors. No significant difference was observed between the expansion of CB and NB at 7, 14 or 21 days of culture in terms of CFU, CD34+ and CD61+ cell subsets. The expansion capacity of BM was significantly lower than that of NB or CB, possibly related to the low proportion of CD34+ CD38- cells observed at day 0. There was a relatively rapid expansion of NB which was evident at day 7 whilst the expansion of CB and BM remained low, suggesting a speedy maturation process in the postnatal infant. The expanded cells, being heterogeneous in their morphology and cell surface marker expression, were mostly of the myeloid lineage (CD45+, CD33+ and HLA-DR+). Our results showed that the expansion capacity of NB is comparable to that of CB and if transplanted, the expanded products of NB might contribute to the engraftment kinetics of the neutrophil and megakaryocyte lineage.

Antigens, CD34↗
PubMed1999

Nephelometric determination of micro amounts of nucleic acids with protamine sulfate.

Nucleic acids can form large particle complexes with protamine sulfate by electrostatic forces, which results in strong light scattering. Based on this, a nephelometric method is described for sensitive and convenient determination of nucleic acids with protamine sulfate by using a common spectrofluorimeter. Maximum light scattering is produced in the range of pH 2.2-4.4 with the same excitation and emission wavelengths at 365 nm. Under optimal conditions, the calibration curves are linear in the range 0.05-60.0 micrograms cm-3 for nucleic acids. The corresponding detection limits are 12.5 ng cm-3 for calf thymus DNA, 9.0 ng cm-3 for fish sperm DNA, and 18.0 ng cm-3 for yeast RNA, respectively. Six synthetic samples are determined with satisfactory results. The relative standard deviation of five replicate measurements is 3.2% for 2.0 micrograms cm-3 calf thymus DNA.

Animals↗