In vitro generation of human cytotoxic T lymphocytes specific for peptides derived from prostate-specific antigen

BACKGROUND

Protein antigens are presented to cytotoxic T lymphocytes as small peptides (approximately 9-10 amino acids long) bound to class I molecules of the major histocompatibility complex. The identification of tumor-associated antigens and specific peptide epitopes (i.e., antigenic determinants) may be useful in the development of anticancer vaccines. The generation of a cytotoxic T-cell response to one peptide epitope (amino acids 146-154) of human prostate-specific antigen (PSA) has been reported.

PURPOSE

Our aim was to identify novel PSA peptides capable of eliciting specific cytotoxic T-cell responses.

METHODS

Candidate peptides were identified on the basis of the following criteria: 1) they contained consensus amino acid motifs for binding to HLA-A2, which is the most common type of class I molecule; 2) they lacked strong homology with PSA-related kallikrein proteins; and 3) they were capable of stabilizing HLA-A2 class I molecules on the surface of human T2 (transport deletion mutant) cells, which are defective in antigen presentation. T-cell lines capable of killing (i.e., lysing) T2 target cells that had been pulsed with specific PSA peptides were generated from three different males (two disease-free individuals and one patient with prostate cancer) by incubating peripheral blood mononuclear cells with the peptides and interleukin 2. Specific cell lysis was monitored by the release of radioactivity from target cells that had been labeled with [111In]oxyquinoline.

RESULTS

Two novel PSA peptides capable of eliciting cytotoxic T-cell responses were identified; these peptides were designated PSA-1 (amino acids 41-150) and PSA-3 (amino acids 154-163). Four different cytotoxic T-cell lines were generated in response to these peptides-three against PSA-3 and one against PSA-1. Specific lysis of peptide-pulsed T2 cells by the T-cell lines was blocked by the addition of a monoclonal antibody directed against class I molecules. The T-cell lines were also capable of lysing PSA-positive, HLA-A2-positive LNCaP cells (human prostate carcinoma cells). The specificity of LNCaP cell lysis was shown by the following: 1) the inability of added human K562 (chronic myelogenous leukemia) cells to inhibit it, 2) the ability of added anti-HLA-A2 antibodies to block it, and 3) the inability of the T-cell lines to induce substantial lysis of PSA-negative, HLA-A2-positive human cancer cells.

IMPLICATIONS

Our studies form a rational basis for the use of PSA peptides or recombinant vectors encoding PSA in the development of anticancer vaccine immunotherapy protocols for patients with prostate cancer.

Observation of coherent transients by use of current switching of a semiconductor diode laser

We have observed optical free induction decay on the (3)H(6)(1) ? (3)H(4)(1) transition of Tm(3+) ions in LaF(3), using an external-cavity diode laser. The diode-laser frequency was switched by the application of a current step, and the resulting transient was detected by heterodyne beating with the laser at its new frequency. This provides a simple new way to measure coherent transients. The beat note shows a frequency chirp that gives a real-time measure of the diode-laser frequency. This result is attributed to changes in the laser lattice temperature on the microsecond time scale.

Plant polyphenols: biologically active compounds or non-selective binders to protein?

Twenty phenolic compounds, representatives of proanthocyanidins and gallic acid/hexahydroxyldiphenic acid esters of glucose, have been assessed for their ability to inhibit binding of specific radioligands to 16 receptors. The receptors utilized were alpha 1-, alpha 2- and beta-adrenoceptors, adenosine 1, dopamine 1 and 2, muscarinic, Ca2+ channel, sulphonylureas, 5HT1, 5HT1A, 5HT2, histamine 1, benzodiazepine, opiate and Na+/K/ATPase. These phenolic compounds failed to inhibit ligands binding to 10 of the receptors under the test conditions. The most susceptible receptors to phenolic binding were beta-adrenergic, 5HT1 and opiate. Some of the compounds tested showed selectivity for a single or for two receptors. The inhibition of binding of radioligands to receptors by the phenolic compounds cannot be explained solely in terms of phenolic-protein binding. The results indicate that the removal of tannins from plant extracts prior to screening for receptor activities may result in missing biologically active compounds with specificity of action.

[The establishment and evaluation of abdominal aorta thrombosis model in rat]

An animal model of abdominal aorta thrombosis based on Virchow's thrombosis principle was induced by endothelium denudation with a polyethylene catheter combining severe stenosis with an aortic constriction in rats. A total of 37 rats were involved in thrombosis induction. Among them thrombus developed in 27 rats. Mean length of thrombus was 8.53 +/- 1.42 mm. The contractibility of vascular wall in the thrombotic group significantly reduced.

Integrity of p53 in hepatitis B x antigen-positive and -negative hepatocellular carcinomas

Inactivation of the tumor suppressor p53 seems to be important to the pathogenesis of hepatocellular carcinoma (HCC) associated with chronic hepatitis B virus infection. Although this inactivation may be due to mutations in the p53 gene, recent evidence suggests that the hepatitis B virus-encoded X antigen (HBxAg) binds to and inactivates wild-type p53. Hence, experiments were designed to test the hypothesis that there is a low frequency of p53 mutations in HBxAg-positive HCC. HBxAg and p53 were assayed by immunohistochemistry (IHC) in HCC and nontumor liver from 16 Chinese patients, half of whom were hepatitis B surface antigen carriers. HBxAg was detectable in tumor and/or nontumor cells from all patients by IHC; six of these samples also had detectable p53. To determine whether p53 detection by IHC, and hence stabilization, is associated with mutation, sequencing of p53 exons 5-8 was performed with each patient sample. Wild-type sequences were found in 13 of 16 HBxAg-positive cases (81%). Hence, HBxAg is a common marker of HCC that correlates with the persistence of wild-type p53 among both carriers and noncarriers. The low frequency of p53 mutations in HCC in these patients implies that p53 inactivation may occur predominantly by complex formation with HBxAg.

Exercise training in Otsuka Long-Evans Tokushima Fatty rat, a model of spontaneous non-insulin-dependent diabetes mellitus: effects on the B-cell mass, insulin content and fibrosis in the pancreas

The effects of exercise on alterations in the amount of B-cell mass, insulin content and fibrous tissue present in the pancreas were examined for a diabetic state induced by a 70% pancreatectomy and a prediabetic state in Otsuka Long-Evans Tokushima Fatty (OLETF) rat, a model for the spontaneous development of non-insulin-dependent diabetes mellitus (NIDDM). The rats (5-weeks old) were trained either by a 6-week running program or sedentary controls, and at 6-weeks of age, received either a 70% pancreatectomy or a sham-pancreatectomy (sham). As in our previous report, persistent hyperglycemia was detected after surgery for both trained pancreatectomized (Px) and sedentary Px groups. In the nondiabetic sham rats, exercise training resulted in a significantly smaller increase in body weight and beneficial effects on the pancreas as reflected by an increase in pancreatic volume, accompanied by increases in B-cell mass and insulin content as well as less connective tissue in the pancreas compared with the sedentary nondiabetic sham rats. The effect was not sufficient to improve sustained hyperglycemia in the trained diabetic Px rats. This is probably due to a decreased capacity for B-cell proliferation in response to an increased demand for insulin. Although exercise failed to improve this inherent defect in B-cell proliferation, it ameliorated the further deterioration of the pancreas which occurred with hyperglycemia, and resulted in a higher quantity of insulin stored per milligram of B-cell mass (as function of B-cell mass) and less fibrosis in the pancreas, compared with the sedentary diabetic Px rats. The findings of the present study suggest that exercise training has a beneficial effect on the pancreas in the nondiabetic state, and also exerts some positive effects in the diabetic state in this model rat.

Characterization of glutathione conjugates of pyrrolylated amino acids and peptides by liquid chromatography-mass spectrometry and tandem mass spectrometry with electrospray ionization

High-performance liquid chromatography (HPLC) coupled with electrospray mass spectrometry (ES-MS) and tandem mass spectrometry (MS-MS) was used to identify the products formed upon reaction of lysine-containing peptides with the neurotoxicant 2,5-hexanedione (2,5-HD). In addition, secondary autoxidative reaction products of the resultant alkylpyrroles with the biological thiol, glutathione, were characterized. ES mass spectra of the HPLC-separated conjugates showed intense [M+H]+ ions as well as several ions formed by amide and C-S bond cleavage. The glutathione conjugates of pyrrolylated amino acids and peptides were analyzed by ES ionization and MS-MS, and product-ion spectra showed fragmentation pathways typical of glutathione conjugates. ES-MS-MS analysis of a synthetic nonapeptide modeling a sequence found in neurofilament proteins showed pyrrole formation after incubation with 2,5-HD, and sequence ions were used to assign the position of the pyrrole adduct. Subsequent reaction of the pyrrolylated peptide with reduced glutathione was evidenced by a shift in m/z of the sequence ions of the reaction products with or without prior methylation. The results demonstrate the utility of ES-MS and ES-MS-MS in the characterization of xenobiotic-modified peptides and confirm that stable pyrrole-thiol conjugates are formed by the reaction of biological thiols with pyrrolylated peptides.

Intracellular expression of single-chain variable fragments to inhibit early stages of the viral life cycle by targeting human immunodeficiency virus type 1 integrase

Integration of viral DNA into a chromosome of the infected host cell is required for efficient replication of a retroviral genome, and this reaction is mediated by the virus-encoded enzyme integrase (IN). As IN plays a pivotal role in establishing infection during the early stages of the retroviral life cycle, it is an attractive target for therapeutic intervention. However, the lack of effective antiviral drug therapy against this enzyme has led to the testing of other novel approaches towards its inhibition. In these studies, a panel of anti-human immunodeficiency virus type 1 (anti-HIV-1) IN hybridomas has been used in the construction of single-chain variable antibody fragments (SFvs). The monoclonal antibodies produced by these hybridomas, and derived SFvs, bind to different domains within IN. We now demonstrate that intracellular expression of SFvs which bind to IN catalytic and carboxy-terminal domains results in resistance to productive HIV-1 infection. This inhibition of HIV-1 replication is observed with SFvs localized in either the cytoplasmic or nuclear compartment of the cell. The expression of anti-IN SFvs in human T-lymphocytic cells and peripheral blood mononuclear cells appears to specifically neutralize IN activity prior to integration and, thus, has an effect on the integration process itself. These data support our previous studies with an anti-HIV-1 reverse transcriptase SFv and demonstrate further that intracellularly expressed SFvs can gain access to viral proteins of the HIV-1 preintegration complex. This panel of anti-HIV-1 IN SFvs also provides the tools with which to dissect the molecular mechanism(s) directly involved in integration within HIV-1-infected cells.

Application of radioligand receptor binding assays in the search for CNS active principles from Chinese medicinal plants

Extracts of Schefflera bodinieri and S. delavayi (Araliaceae), Celastrus angulatus and C. orbiculatus (Celastraceae), Clerodendrum mandarinorum and C. bungei (Verbenaceae), Periploca callophylla and P. forrestii (Asclepiadaceae), Alangium platanifolium (Alangiaceae) and Uncaria rhynchophylla (Rubiaceae) were assessed for CNS activity against 18 radioligand receptor binding assays. The receptors used were alpha 1-, alpha 2- and beta-adrenoceptors, 5HT-1, 5HT-1A, 5HT-2, opiate, adenosine-1, benzodiazepine, Ca+2 channel, sulphonylureas, dopamine-1, dopamine-2, muscarinic, histamine-1, Na+/K+ ATPase, GABAA and GABAB. The results indicate that these ligand-receptor binding assays are useful for understanding the mode of action of herbal medicines and for bioassay guided fractionation of plant active ingredients.

Pancreatic A-cell function in the partially pancreatectomized Otsuka Long-Evans Tokushima Fatty rat, a model of spontaneous non-insulin-dependent diabetes mellitus

We examined whether a 70% pancreatectomy changes the morphofunctionality of pancreatic A cells in a model rat (Otsuka Long-Evans Tokushima Fatty [OLETF]) with non-insulin-dependent diabetes mellitus. Male OLETF rats aged 6 weeks were assigned to two groups: partial pancreatectomy (Px) and sham pancreatectomy (sham). The Px group was divided into three subgroups based on treatment received after surgery, which included treatment with nicotinamide, phlorhizin, or saline. As a control, their diabetes-resistant counterparts, Long-Evans Tokushima Otsuka (LETO) rats, were similarly treated and grouped. Six weeks after surgery, plasma glucagon responses to arginine- and insulin-induced hypoglycemia were examined. In addition, the glucagon content and morphological features of pancreatic A cells in Px-remnant and remnant-equivalent pancreata were investigated 7 weeks after surgery. A sustained nonfasting hyperglycemia was evident in Px OLETF rats, which was ameliorated by administration of nicotinamide. The glucagon content and A-cell mass were not decreased significantly in the remnant pancreas of saline- and phlorhizin-treated Px animals of either strain but increased in nicotinamide-treated animals compared with those in the remnant equivalent of the respective sham rats. The areas under the response curves of plasma glucagon (zigma IRG) during an arginine infusion test and 90 minutes of insulin-induced hypoglycemia were 1,010.7 +/- 72.9, 1,083.1 +/- 95.3, 1,029.6 +/- 65.0, and 1,779.8 +/- 226.9 pmol.L-1.min-1 versus 1,997.0 +/- 283.1,2,217.0 +/- 395.0, 1,479.6 +/- 78.0, and 3,466.4 +/- 174.0 pmol.L-1.min-1 in phlorhizin-, nicotinamide-, and saline-treated Px OLETF and sham OLETF rats, respectively. A similar trend was observed for differences in the response of pancreatic A cells to both stimuli among various groups of LETO rats. There was no significant difference in sigma IRGs during both tests between OLETF and LETO rats with similar treatments, except during an insulin tolerance test (ITT) in saline-treated Px rats. The magnitude of the plasma glucagon response to both stimuli in the test animals was roughly parallel to the glucagon content in the pancreas. These findings suggest that differences in the proliferation and responsiveness of pancreatic A cells between OLETF and LETO rats after a 70% pancreatectomy are not nearly as significant as compared with B cells.

Solid-state 13C-NMR spectroscopy of adduction products of 2,5-hexanedione with ribonuclease, albumin, and rat neurofilament protein

The Paal-Knorr condensation reaction between the gamma-diketone 2,5-hexanedione (2,5-HD) and epsilon-amine moieties of proteins of various molecular weight, including ribonuclease (RNase), bovine serum albumin (BSA) and rat neurofilament (NF), has been investigated by solid-state 13C-NMR spectroscopy. These proteins all reacted with 2,5-HD with the formation of 2,5-dimethylpyrrole (2,5-DMP) derivatives. The size and complexity of the protein affected the rate of formation of 2,5-DMP derivatives. Using the selective reducing reagent NaCNBH3, the Paal-Knorr reaction intermediates were trapped by conversion into amines, which were identified by solid-state NMR spectroscopy. The secondary autoxidation reaction following the formation of 2,5-DMP derivatives was also studied by solid-state NMR spectroscopy.

Chemical and biological investigation of the root bark of Clerodendrum mandarinorum

A 70% EtOH extract of Clerodendrum mandarinorum root bark was assessed for CNS activity against 18 radioligand receptor binding assays. The results showed that the extract was able to bind to opiate, adenosine-1, alpha 2-adrenergic, 5HT-1, 5HT-2, dopamine-2, histamine-1, GABA(A), and GABA(B) receptors. Fourteen compounds were isolated and identified by El-MS, 1H-NMR and 13C-NMR spectra as known triterpenoids (friedelanone, lupeol, betulinic acid), steroids (24S-stigmata-5,25-dien-3 beta-ol,22E,24S-stigmata-5,22,25-trien-3 beta-ol), flavonoids (cirsimaritin, cirsimaritin-4'-glucoside, quercetin-3-methyl ether), tetra-hydro-alpha-pyrone and saccharides (sucrose, alpha-D- and beta-D-glucopyranose, ethyl-alpha-D-glucopyranoside, 2-ethyl-beta-D-fructofuranoside). The isolated compounds were assessed for activity by the radioligand receptor binding assays. Betulinic acid and ethyl-alpha-D-glucopyranoside showed weak activities against sulphonylureas (IC50 = 7.5 microM) and muscarinic receptors (IC50 = 5.5 microM), respectively. Cirsimaritin-4'-glucoside was weakly active in the adenosine-1 binding assay (IC50 = 3.0 microM), whereas seven structurally related flavonoids, not isolated from C.mandarinorum, were inactive.

Oligonucleotide analysis by capillary polymer sieving electrophoresis using acryloylaminoethoxyethanol-coated capillaries

Capillary polymer sieving electrophoresis using dynamic sieving polymer solutions provides size-based separations of oligonucleotides. The polymer sieving system described here resolves single-stranded oligonucleotides with single-base resolution up to lengths of 30 bases within 10 min. The effect of temperature on the separation of synthetic oligonucleotide standards was examined between 20 degrees C and 40 degrees C, with optimal performance at 35-40 degrees C. By adding urea to the sieving buffer single-base resolution could be extended to 60 bases in about 40 min. Best performance was achieved with capillaries coated with a new monomer, acryloylaminoethoxyethanol. This coating provides the necessary stability to ensure long lifetimes.

Tetrahydrobiopterin biosynthesis in C6 glioma cells: induction of GTP cyclohydrolase I gene expression by lipopolysaccharide and cytokine treatment

The possibility that 5,6,7,8-tetrahydrobiopterin (BH4) biosynthesis is stimulated in glial cells by treatment with lipopolysaccharide (LPS) and tumor necrosis factor (TNF-alpha) was examined in the astrocyte-derived C6 glioma cell line. Under basal culture conditions BH4 levels were found to be at the limit of detection. Concurrent treatment with 10 micrograms/ml LPS and 50 ng/ml TNF-alpha caused a time-dependent 13-fold increase in the levels of BH4. This treatment paradigm also induced nitric oxide synthase activity, as evidenced by increased levels of nitrite, an oxidized metabolite of NO, in the culture medium. LPS and TNF-alpha treatment led to a 25-fold increase in GTPCH enzyme activity, the first and rate-limiting enzyme in BH4 synthesis, and a corresponding 23-fold increase in GTPCH protein levels. Northern blot analysis showed that increased levels of GTPCH mRNA preceded changes in GTPCH protein, GTPCH enzyme activity and BH4 levels and reached a maximal of 44-fold that was sustained for at least 48 h. These results demonstrate that LPS and TNF-alpha stimulate de-novo BH4 biosynthesis and suggest that C6 cells offer a model system for studying the molecular events that control the induction of GTPCH gene expression and BH4 synthesis in glial cells.

[A preliminary study on the relationship between Streptococcus and Neisseria,Veillonella in an artificial mouth model]

The viable cell count of monobacterial plaque of Streptococcus and mixed bacterial plaque of streptococcus and Neisseria Veillonella,also the demineralization caused by the plaques were observed.The assumption that Neisseria and Veillonella might reduce demineralization of enamel caused by streptococcus was confirmed.The relationship between streptococcus and Neisseria,Veillonella were preliminarily found out.

TAR- and Tat-independent replication of human immunodeficiency virus type 1 in human hepatoma cells

The molecular mechanisms involved in the regulation of human immunodeficiency virus type 1 (HIV-1) replication may differ in various cell types and with various exogenous stimuli. TAR/Tat interactions play important roles in HIV-1-long terminal repeat (LTR)-directed transcription, and have become specific targets in molecular therapies for blocking HIV-1 replication. As we previously reported, astrocytic glial cells, which can support HIV-1 replication in cell culture and may be infected in vivo, provide an intracellular milieu in which TAR mutant HIV-1 viruses may replicate. In further studies of this molecular model, several divergent human cell types were analyzed for both TAR- and Tat-independent HIV-1 replication. Human hepatoma cell lines, which can be productively infected by HIV-1 after the hepatoma cells are transduced with the human CD4 receptor gene, were found to support high levels of HIV-1 replication. In these studies, utilizing a transient transfection system with wild-type and various TAR, Tat, or combined TAR/Tat mutant HIV-1 proviral constructs, we demonstrate TAR-independent replication in unstimulated human hepatoma cells. Remarkably, in human hepatoma cells, HIV-1 replication is not only independent of TAR but also can be independent of Tat expression. It is further demonstrated, using electrophoretic mobility shift assays (EMSAs) and an in situ UV cross-linking system, that human hepatoma cells contain novel endogenous cellular proteins that bind to the proviral HIV-1 5' LTR in the downstream region, between nucleotides +38 to +125 on proviral DNA. This alternative regulatory pathway of TAR- and Tat-independent viral production may provide a new system to dissect further the interactions of Tat/TAR and determine the role of the TAR element, in its DNA form, in HIV-1 replication.

Poor capacity for proliferation of pancreatic beta-cells in Otsuka-Long-Evans-Tokushima Fatty rat: a model of spontaneous NIDDM

Otsuka-Long-Evans-Tokushima Fatty (OLETF) rat, a genetic model of spontaneous development of NIDDM, exhibits hyperglycemic obesity with hyperinsulinemia and insulin resistance similar to that in humans. It is still unclear whether a defect in the beta-cell proliferation per se is the primary pathogenetic event in OLETF rat. To determine whether it is, we used partially pancreatectomized rats as a model, with administration of phlorizin to control blood glucose level, to examine whether the capacity for proliferation of beta-cells during hyperglycemia or normoglycemia differs between OLETF and their diabetes-resistant counterparts, Long-Evans-Tokushima-Otsuka (LETO) rats. We also examined whether such a defect, if present, could be improved by nicotinamide. Male rats, 6 weeks of age, were allocated at random to two groups: 70% pancreatectomy (Px) and sham-pancreatectomy (sham). Each group was divided into four subgroups by date of killing after surgery: 3-day, 7-day, 28-day (treated with phlorizin, nicotinamide, or saline), and 91-day. A sustained hyperglycemia was evident in the Px OLETF rats after surgery, which was associated with insufficient proliferation of beta-cells, characterized by decrease in beta-cell labeling index in proportion to decrease in beta-cell mass and reduction in insulin content in the remnant pancreas. This defect was unaffected by restoration of normoglycemia induced by phlorizin injection. Administration of nicotinamide, however, ameliorated the sustained hyperglycemia by increasing beta-cell proliferation. These findings suggest that OLETF rats have poor capacity for proliferation of pancreatic beta-cells and that this change may be the critical pathogenetic event before the onset of overt diabetes.

Angiotensin II type 1 receptor modulation of neuronal K+ and Ca2+ currents: intracellular mechanisms

Angiotensin II (ANG II) elicits an ANG II type 1 (AT1) receptor-mediated decrease in voltage-dependent K+ current (Ik) and an increase in voltage-dependent Ca2+ current (ICa) in neurons cocultured from newborn rat hypothalamus and brain stem. Modulation of these currents by ANG II involves intracellular messengers that result from an AT1 receptor-mediated stimulation of phosphoinositide hydrolysis. For example, the effects of ANG II on IK and ICa were abolished by phospholipase C antagonists. The reduction in IK produced by ANG II was attenuated by either protein kinase C (PKC) antagonists or by chelation of intracellular Ca2+. By contrast, PKC antagonism abolished the stimulatory effect of ANG II on ICa. Superfusion of the PKC activator phorbol 12-myristate 13-acetate produced effects on IK and ICa similar to those observed after ANG II. Furthermore, intracellular application of inositol 1,4,5-trisphosphate (IP3) elicited a significant reduction in IK. This suggests that the AT1 receptor-mediated changes in neuronal K+ and Ca2+ currents involve PKC (both IK and ICa) and IP3 and/or intracellular Ca2+ (IK).

Gallium-67 scanning for detection of alveolitis in idiopathic pulmonary fibrosis and sarcoidosis

OBJECTIVE

To investigate 67Gallium scanning for the detection of alveolitis in idiopathic pulmonary fibrosis and sarcoidosis.

PATIENTS AND METHODS

67Ga scintigraphy was performed in 14 patients with IPF (age: mean +/- s = 58.3 +/- 10.3 years), 13 patients with sarcoidosis (age: mean +/- s = 46.9 +/- 9.0 years) and 11 controls (age: mean +/- s = 44.0 +/- 10.5 years).

RESULTS

Lung/thigh ratio was respectively 3.18 +/- 0.07 in IPF, 3.12 +/- 0.94 in sarcoidosis and 2.11 +/- 0.26 in controls. IPF and sarcoidosis groups had a significantly higher lung/thigh ratio comparing with the control group (P < 0.05). Three patients received 67Ga scanning examination after corticosteroid therapy and the 67Ga uptake decreased.

CONCLUSIONS

The 67Ga scintigraphy is useful in monitoring the activity and extent of alveolitis.

Differential V region mutation of two transfected Ig genes and their interaction in cultured B cell lines

We have established B cell culture systems in which transfected and stably integrated Ig constructs spontaneously undergo high rates of variable (V) region mutation. Mutation rates were determined using reversion analysis of an Ig V region nonsense codon (Vn). A construct (Vn/gamma2a) in which a Vn was associated with the gamma2a constant region and its intervening and immediate flanking sequences mutated at a high rate of 2.2 x 10(-4)/bp/generation in the NSO myeloma cell line. This same Vn, when associated with the mu constant region (Vn/mu), mutated at a 1000-fold lower rate in NSO. The Vn/gamma2a construct also mutated at high rates in the 18.81 pre-B and the S107 myeloma cell lines and at a low rate in the J558 myeloma cell line. In NSO, the presence of the gamma2a construct raised the mutation rate of the mu construct and the mu decreased the mutation rate of gamma2a. These results suggest that there is both positive and negative regulation of V region mutation and that different cell lines express different combinations and/or amounts of trans-acting factors that are involved in the mutational process.

Targeting human immunodeficiency virus type 1 reverse transcriptase by intracellular expression of single-chain variable fragments to inhibit early stages of the viral life cycle

Novel molecular approaches to inhibit human immunodeficiency virus type 1 (HIV-1) infection have received increasing attention because of the lack of effective antiviral drug therapies in vivo. We now demonstrate that cells can be intracellularly immunized by cytoplasmic expression of single-chain variable antibody fragments (SFv) which bind to the HIV-1 reverse transcriptase (RT) enzyme. The expression of anti-RT SFv in T-lymphocytic cells specifically neutralizes the RT activity in the preintegration stage and affects the reverse transcription process, an early event of the HIV-1 life cycle. Blocking the virus at these early stages dramatically decreased HIV-1 propagation, as well as the HIV-1-induced cytopathic effects in susceptible human T lymphocytes, by impeding the formation of the proviral DNA. These data also demonstrate that intracellular, complete SFvs may gain access to viral proteins of the HIV-1 preintegration complex. These SFvs will provide a tool with which to better understand the molecular mechanisms involved in restricting viral replication in HIV-1-infected cells.

[A study on the influence of zinc on the growth and metabolism of streptococcus in an artificial mouth model]

The influence of zinc on the growth and metabolism of Streptococcus was studied under controlled conditions in an artificial mouth model.the results confirmed the previous conclusion that zinc was capable of inhibiting the growth and metabolism of streptococcus both vivo and in vitro.At the same time,the feasibility of the imitative experiments in an artificial mouth model was proved.

Binding of intracellular anti-Rev single chain variable fragments to different epitopes of human immunodeficiency virus type 1 rev: variations in viral inhibition

Intracellular immunization to target the human immunodeficiency virus type 1 (HIV-1) regulatory protein Rev has been explored as a genetic therapy for AIDS. Efficient intracellular expression of rearranged immunoglobulin heavy and light chain variable regions of anti-Rev monoclonal antibodies, with various vectors, and subsequent inhibition of HIV-1 replication have been previously reported by our laboratories. To further understand the molecular mechanisms and effects that intracellular anti-Rev single chain variable fragments (SFvs) have against HIV-1, via blocking of Rev function, two anti-Rev SFvs which specifically bind to differing epitopes of the Rev protein have been cloned. One SFv binds to the Rev activation domain, and the second SFv binds to the distal C terminus of Rev in the nonactivation region. Further studies now demonstrate that both anti-Rev SFvs lead to variable resistance to HIV-1 infection. Although binding affinity assays demonstrated that the SFv which specifically recognizes the Rev activation domain (D8) had an extracellular binding affinity significantly lower than that of the SFv specific to the nonactivation region (D1O), the SFv D8 demonstrated more potent activity in inhibiting virus production in human T-cell lines and peripheral blood mononuclear cells than did SFv D10. Thus, extracellular binding affinities of an SFv for a target viral protein cannot be used to directly predict its activity as an intracellular immunization moiety. These data demonstrate potential approaches for intracellular immunization against HIV-1 infection, by efficiently blocking specific motifs of Rev to after the function of this retroviral regulatory protein. These studies extend the understanding of the effects, on a molecular level, of SFvs binding to critical epitopes of Rev and further suggest that rational design of SFvs, with interactions involving specific viral moieties which mediate HIV-1 expression, may hold promise for the clinical application of genetic therapies to combat AIDS.

A comparison of values of annual limits on intake presented in ICRP 61 and 10 CFR part 20

The latest (1991) major revision of the U.S. Nuclear Regulatory Commission regulations incorporates internal dose concepts and primary and secondary dose limits adapted from the recommendations of the International Commission on Radiation Protection Publication 30 published in 1979. This work compares values of the Annual Limits on Intake (ALIs) reported in the latest U.S. regulations with those recommended in the more recent, 1990, International Commission on Radiation Protection Publication 61. Overall trends in the updated ALI values compared to those in the regulations, as well as radionuclides exhibiting greater than +/-50% changes in these values, after correcting for differences in the primary dose limits, are reported.

Recombinant human Fab antibody fragments to HIV-1 Rev and Tat regulatory proteins: direct selection from a combinatorial phage display library

A human Fab phage display library has been produced from peripheral blood lymphocytes of an individual who was asymptomatic after 10 years of infection with human immunodeficiency virus type-1 (HIV-1). The library was panned against the HIV-1 Rev and Tat regulatory proteins and several clones, producing Fab binding to these proteins, were isolated (3 to Rev and 4 to Tat) with binding constants varying from 10(-6)M to 10(-8)M. DNA sequencing demonstrated two unique anti-Rev Fab clones, but the four anti-Tat Fab comprised only two unique IgG1 heavy chain Fd fragments, illustrating redundancy of light chains. Peptide mapping of the epitopes recognized by these Fab indicated that three of the anti-Tat Fab were directed to the functional domain between amino acid residues 22-33 of the Tat molecule, and that binding was inhibited by reduction of this cysteine-rich region with dithiothreitol. The anti-Rev Fab were directed to sites adjacent to the Rev basic nucleolar localization sequence (residues 52-64) and to the Rev activation domain (residues 75-88). Binding constants were of a similar order to that of an anti-Rev single-chain Fv fragment (SFv) used successfully for intracellular immunization, and as such intracellular effects with the human anti-Tat and anti-Rev Fab are not precluded. These newly described human antibody fragments to HIV-1 regulatory proteins may be critical moieties for gene therapeutic protocols, to control HIV-1 replication in human cells.

[Simple artificial mouth model]

A simple artificial mouth model is established under our laboratory condition. Development of monobacterial plaque and mixed bacterial plaque was studied in this artificial mouth model. The samples were subjected to viable count, microhardness measurement, etc. The result showed that the controlled conditions of the model can be used to study plaque development and earlier enamel lesion production on a time-dependent basis. It is concluded that the simple artificial mouth model is suitable for a wide range of dental applications.

Fibronectin degradation in chronic wounds depends on the relative levels of elastase, alpha1-proteinase inhibitor, and alpha2-macroglobulin

The goal of our studies was to learn about the mechanism of fibronectin degradation in chronic ulcers. We found that the appearance of fibronectin fragments in chronic ulcer wound fluid correlated with elevated levels of elastase and cleavage of the proteinase inhibitors alpha2-macroglobulin (alpha2-M) and alpha 1-proteinase inhibitor (alpha1-P1). Some wound fluid samples retained the capacity to degrade fibronectin in vitro. Degradation of fibronectin by these samples was blocked by specific inhibitors of neutrophil elastase but not by inhibitors of metalloproteinases. Addition of human neutrophil elastase to mastectomy fluid, an acute wound fluid, resulted in formation of alpha1-PI and alpha2-M complexes and cleavage products resembling those observed in chronic wound fluid. Moreover, degradation of fibronectin and processing of matrix metalloproteinase MMP-9 occurred under these conditions. Taken together, our findings suggest that elevated levels of neutrophil elastase are responsible for fibronectin degradation in the chronic wound environment.

Evaluation of feline leukemia virus control measures

A susceptible-infected-recovered-susceptible (SIRS) model of the epidemiology of feline leukemia virus is formulated and analysed. The dynamics of the disease are dramatically different in no-risk, low-risk and high-risk subpopulations of asocial, free roaming, and multiple cat household cats. Among low risk (<1% prevalence) free roaming cats, the model predicts that an effective immunization rate of 4% year-1, or an effective removal rate of 8% year-1 are adequate to control the disease completely. Under higher risk (10% prevalence) conditions, an effective immunization rate of 23-72% year-1 or a removal rate of 69-145% year-1 are required for control. At very high (30%) prevalence rates, even heroic measures may not suffice to substantially reduce disease prevalence: a vaccination rate of 100% year-1 even if attainable, would only slightly reduce disease prevalence from 30% to 29%. We conclude that the current estimated effective feline leukemia virus immunization rate of 11-19% of the general population is inadequate to provide herd immunity in the subpopulation of cats which are genuinely at risk of infection. A substantial increase in the vaccination rate and/or intensification of test and removal efforts in the at risk population would be required to attain an effective level of protection.

Capillary isoelectric focusing

Capillary isoelectric focusing is a useful analytical technique for characterization of protein mixtures and determination of protein isoelectric points. It is particularly useful in separation of protein glycoforms (Fig. 5), characterizing protein microheterogeneity (Fig. 6), and resolution of charge variants (Fig. 7). The capillary focusing process is analogous to conventional isoelectric focusing in gels, while the requirement for zone mobilization is unique to the capillary format with on-tube detection. A variety of mobilization methods have been described, and the selection of the mobilization method for a particular application depends on the capillary type, the instrument configuration, and the type of proteins to be analyzed. Capillary IEF is generally successful for proteins with a molecular weight up to about 150,000 that exhibit good solubility in aqueous buffers, but may be unsatisfactory for large or hydrophobic proteins. Because of precipitation and variation in mobilization efficiencies, use of internal standards is recommended in most applications. Capillary IEF can be compared to conventional gel IEF in terms of sample throughput and sensitivity. Conventional gels require approximately 4-6 hr to cast, run, and stain the gel, depending on whether silver or Coomassie staining is used. A typical gel contains 10 sample lanes, yielding a throughput of 25-35 min/sample. Capillary IEF separations (including focusing and mobilization) are typically 15-20 min. The mass sensitivity of conventional gel IEF is 36-47 ng for Coomassie staining and 0.5-1.2 ng for silver staining. In capillary IEF, sensitivity will depend on the volume of sample injected; assuming a capillary with a volume of 100 nl is completely filled with sample prior to focusing, the limit of detection will be approximately 1 microgram/ml or 0.1 ng injected. Thus capillary IEF compares favorably with conventional gel IEF in terms of detectivity and analysis time, and has the additional benefit of complete automation of the process including separation and data reduction.

[Inhibitory effect of green tea polyphenols varnish on oral main cariogenic bacteria.]

This study observed the bacteriostatic effect of green tea polyphenols varnish,found green tea polyphenols varnish had significant inhibitory action on Streptococcus mutans,Streptococcus sobrinus and Lactobacilli.growth test showed the growth inhibitory rate of S.mutans and S.sobrinus was positive proportion with the concentration of green tea polyphenols varnish,demonstrated green tea polyphenols varnish possess certain anticariogenic effect.

Intracellular immunization against HIV-1 infection of human T lymphocytes: utility of anti-rev single-chain variable fragments

Genetic therapy offers a potentially promising approach with which to combat human immunodeficiency virus type 1 (HIV-1) infections. Several modalities, using protein- and RNA-based systems, have recently been shown to inhibit HIV-1 replication. A single-chain variable fragment (SFv), constructed from the cDNA of a monoclonal antibody to the HIV-1 regulatory protein Rev, has been demonstrated to potently inhibit HIV-1 replication, when expressed intracellularly in an epithelial cell-line (HeLa-CD4). Murine retroviral shuttle vectors, which express the anti-Rev SFv moiety, have now been constructed. HIV-1 infection was dramatically inhibited in human T-lymphocytic cell-lines, CEM and Sup-T1, transduced with these anti-Rev SFv-expressing vectors. This resistance to high levels of HIV-1 expression was demonstrated in both mixed populations and clones of these cells. Of further potential clinical significance, HIV-1 infection was also potently inhibited in human peripheral blood mononuclear cells (PBMC), transduced with retroviral vectors expressing the anti-Rev SFv molecule. These data suggest that intracellular expression of anti-Rev SFvs, or related approaches, may be utilized as genetic therapy, or intracellular immunization, for HIV-1 infections in vivo.

Molecular characterisation of UK isolates of barley yellow mosaic bymovirus

Several isolates of barley yellow mosaic virus (BaYMV) from different sites in the UK, including some that were virulent on European resistant winter barley cultivars (resistance-breaking strain: BaYMV-2) and some that were not, were examined by RT-PCR, restriction mapping and sequencing of selected parts of the virus genome. Nucleotide and predicted amino acid sequences were determined for the 5'-terminal region, part of the NIa coding region and the coat protein coding region on RNA 1 and an area at the N-terminus of the 70-kDa protein coding region on RNA 2. The sequences differed from those previously reported for a BaYMV isolate from Japan and for two German isolates, one of which was of the BaYMV-2 strain. There were no strain-specific amino acid differences and the few, non-consecutive, nucleotide differences detected were probably not significant and were insufficient to develop a rapid diagnostic test to distinguish BaYMV-2 from other isolates. Restriction mapping of RNA 2 cDNA again showed no consistent strain-related differences. The differences previously reported between the two German isolates are probably not strain-related.

Overexpression of glucose transporters in rat mesangial cells cultured in a normal glucose milieu mimics the diabetic phenotype

An environment of high glucose concentration stimulates the synthesis of extracellular matrix (ECM) in mesangial cell (MC) cultures. This may result from a similar increase in intracellular glucose concentration. We theorized that increased uptake, rather than glucose concentration per se is the major determinant of exaggerated ECM formation. To test this, we compared the effects of 35 mM glucose on ECM synthesis in normal MCs with those of 8 mM glucose in the same cells overexpressing the glucose transporter GLUT1 (MCGT1). Increasing medium glucose from 8 to 35 mM caused normal MCs to increase total collagen synthesis and catabolism, with a net 81-90% increase in accumulation. MCs transduced with the human GLUT1 gene (MCGT1) grown in 8 mM glucose had a 10-fold greater GLUT1 protein expression and a 1.9, 2.1, and 2.5-fold increase in cell myo-inositol, lactate production, and cell sorbitol content, respectively, as compared to control MCs transduced with bacterial beta-galactosidase (MCLacZ). MCGT1 also demonstrated increased glucose uptake (5-fold) and increased net utilization (43-fold), and greater synthesis of individual ECM components than MCLacZ. In addition, total collagen synthesis and catabolism were also enhanced with a net collagen accumulation 111-118% greater than controls. Thus, glucose transport activity is an important modulator of ECM formation by MCs; the presence of high extracellular glucose concentrations is not necessarily required for the stimulation of matrix synthesis.

Immunoglobulin variable region hypermutation in hybrids derived from a pre-B- and a myeloma cell line

Somatic mutation of the variable (V) regions of immunoglobulin genes occurs in vivo at rates that have been estimated to be between 10(-3) and 10(-4) per bp per generation. To study this process in vitro, the 18.81 pre-B-cell line and hybrids derived by fusing 18.81 to the NSO myeloma fusion partner were transfected with a mu heavy-chain construct containing a nonsense mutation in the V region (Vn) or the constant region (Cn). Mutation was quantitated by reversion analysis using the ELISA spot assay to detect single cells secreting IgM. Fluctuation analysis revealed that V-region mutations spontaneously occurred in 18.81 cells at an average rate of 5.8 x 10(-6) per bp per cell generation and in selected 18.81-NSO hybrids at greatly increased rates of 1.6 x 10(-3) to 5.8 x 10(-4) per bp per generation. The Vn construct also reverted frequently in transgenic mice, indicating that it contained sufficient information to mutate at high rates both in vivo and in vitro. Sequence analysis of reverted genes revealed that reversion was due to point mutations. Since the rates and nature of the mutations that are occurring in these transfected genes are similar to those reported in vivo, it should be possible to use this system to identify the cis-acting sequences and trans-acting factors that are responsible for V-region somatic hypermutation.

[Action of Rhodobrum roserm Limpr on changes of red cell aggregation and yield-shear stress in dogs with acute experimental coronary occlusion]

Following acute occlusion of the left anterior descending coronary artery in dogs, significant increases were observed in the red cell aggregation index, yield-shear stress and red cell electrophoretic time in blood drained from ischemic area. When transfusion was performed with Rhodobrum roseum solution from the right femoral vein, significant rises of the above-said items were observed.

Inhibition of 2,5-hexanedione-induced protein cross-linking by biological thiols: chemical mechanisms and toxicological implications

n-Hexane is metabolized to the gamma-diketone 2,5-hexanedione (2,5-HD), a derivative that covalently binds to lysine residues in neurofilament (NF) protein to yield 2,5-dimethylpyrrole adducts. Studies comparing the pyrrole-forming potential and neurotoxic potency of gamma-diketones have demonstrated that pyrrolylation is an absolute requirement in the neuropathogenesis. Autoxidative cross-linking of pyrrolylated NF proteins occurs and is proposed as a second required event. In the present study, the role of nucleophilic thiols and amines in the pyrrole-mediated cross-linking reaction was investigated. When pyrrolylated ribonuclease was incubated with N-acetyllysine, N-acetylcysteine, or glutathione in physiologic buffer (pH 7.4) under air, pyrrole-to-pyrrole cross-linking was inhibited only by the thiol-containing compounds. Stable thiol--pyrrole conjugates containing a bridge from the pyrrole ring at C-3 to the sulfur atom of the thiol were characterized by thermospray LC/MS and 1H-NMR spectroscopy. In contrast to low-molecular-mass thiols, SDS--PAGE studies indicated that, under the same incubation conditions, free thiols present in proteins did not undergo reaction with pyrrole adducts to form cross-links. Further experiments using a low-molecular-mass pyrrole derivative indicated that glutathione may also able to suppress pyrrole dimerization without conjugate formation, possibly via inhibition of a free radical-dependent mechanism. The results suggest the following: (1) 2,5-HD-induced protein cross-linking is mediated primarily by pyrrole-to-pyrrole bridging under physiologic conditions, and (2) glutathione and other low-molecular-mass thiols may inhibit the pyrrole dimerization reaction by two distinct pathways. These findings have significant implications for the mechanism of gamma-diketone neuropathy.

Effects of obesity and inheritance on the development of non-insulin-dependent diabetes mellitus in Otsuka-Long-Evans-Tokushima fatty rats

We studied whether obesity or inheritance was the more important factor in the development of non-insulin-dependent diabetes mellitus (NIDDM) using female Otsuka-Long-Evans-Tokushima Fatty rats (OLETF) possessing one of the diabetic genes, ODB-1, and male Long-Evans-Tokushima-Otsuka rats (LETO) possessing no ODB-1, neither of which were diabetic when bred normally. Diabetes-resistant male LETO rats and female OLETF rats (4 weeks old) were assigned to three groups of 6 rats each, respectively; two groups in which obesity was induced by high calorie 'cafeteria' diet (D), or ventromedial hypothalamus lesions (V) with normal chow diet and a control group fed on normal chow (C). Six male OLETF rats were used as NIDDM positive controls. The mean daily energy intakes of obese male LETO and female OLETF rats were higher than those of the respective C groups. At 27 weeks of age, the average body weights of the obese LETO and female OLETF rats were significantly higher than those of the respective C groups and similar to that of the male OLETF group. Abdominal fat deposits of the obese groups were significantly higher than those of the respective C groups. At 28 weeks of age, the cumulative incidence of diabetes mellitus in obese LETO rats was 0% in group D and 17% in group V, while that of obese female OLETF rats in groups D and V were 100%. At 29 weeks of age, the plasma immunoreactive insulin (IRI) responses to glucose in obese female OLETF rats, groups D and V, were higher than that in group C. In obese LETO rats, insulin-stimulated glucose disposal in vivo was similar to that in group C, but in obese female OLETF rats, it was reduced to 41% in group D and 37% in group V of that in group C. Sections of islets of the pancreas of obese LETO rats appeared histologically normal, whereas those of obese female OLETF rats showed enlarged multilobulated fibrotic islets. These results demonstrate that obesity is necessary, but not sufficient alone for the development of NIDDM in these rat models.

A well-differentiated B-cell line is permissive for somatic mutation of a transfected immunoglobulin heavy-chain gene

pSV2neo plasmids containing an IgM heavy-chain gene with nonsense mutations in either the variable (V) or the constant (C) region were transfected into four differentiated mouse plasma cell lines: S107 and the NSO fusion partner (myeloma cell lines) and 2C3 and 36.65 (hybridoma cell lines). The frequencies of reversion of the nonsense mutations in multiple independent transfectants were determined with the spot ELISA and rates of reversion were calculated by fluctuation analysis. Mutations in both V and C regions were confirmed by sequence analyses. In the S107 cell line, spontaneous point mutations occurred in the V region at a rate of approximately 5 x 10(-5)/bp per cell generation, > 400-fold higher than the rate of V-region mutation in the NSO cell line and considerably higher than the rates in 2C3 and 36.65 hybridoma cell lines. These studies suggest that S107 is a relatively permissive cell line in which V-region mutations can occur constitutively, even though it represents a late stage of B-cell differentiation. Further, the results show that the construct used contains sufficient information in its flanking and coding sequences to allow a relatively high rate of V-region mutation, at least in the S107 cell line.

Is caloric restriction effective in preventing diabetes mellitus in the Otsuka Long Evans Tokushima fatty rat, a model of spontaneous non-insulin-dependent diabetes mellitus?

Studies were made on the effectiveness of caloric restriction in preventing the development of diabetes mellitus in a model rat (Otsuka-Long-Evans-Tokushima Fatty; OLETF) with non-insulin-dependent diabetes mellitus (NIDDM). Groups of 8 male OLETF rats aged 5 weeks were supplied with rat chow ad libitum (100% group) and 85% and 70% of the amount of food consumed by the 100% group (85% and 70% groups, respectively). The average weights of the 100%, 85% and 70% groups were 617, 536 and 450 g at 19 weeks of age and their abdominal fat deposits were 50, 38 and 21 g, respectively, at 22 weeks of age when they were killed. At 20 weeks of age, the cumulative incidences of diabetes mellitus in the 100%, 85% and 70% groups were 67%, 13% and zero, respectively. The plasma immunoreactive insulin (IRI) levels 60 and 120 min after oral glucose administration were significantly lower in the 70% group than in the other groups. In vivo insulin-stimulated glucose uptake measured by a euglycemic clamp technique, was significantly higher in the 70% group than in the 100% group. There was no significant difference in the glucose transporter 4 protein levels of skeletal muscles in the three groups, but the highest ratio of glucose transporter 4 in the plasma membrane to that in intracellular membranes was observed in the 70% group. Morphological studies on the pancreas of rats in the 100% group showed enlarged multilobulated fibrotic islets, whereas sections of islets of rats in the other groups appeared normal, though slightly enlarged. These results demonstrate that caloric restriction is effective in preventing NIDDM in diabetes-prone rats, probably due to increased insulin sensitivity.

[Applied DNA-DNA hybridization in determination of oral Streptococcus.]

Quantitative measurement of DNA-DNA hybridization is a new technique for determination of unknown bacteria.It is more valuable how to identify strains which is rare difference on phenotypic characteristics.It is important to resolve bactericial taxionmy and identify new strain.Four strain of Streptiococcus are determined by hybridization of DNA.Some technique problems are discussed.Such as purification,precision of DNA and temperature as well as time of DNA hybridization and standard of judgment.

Identification of neutrophil elastase as the proteinase in burn wound fluid responsible for degradation of fibronectin

To identify proteinases responsible for fibronectin degradation in the wound environment we studied wound fluid obtained from burn patients. Immunoblotting experiments showed that extensive degradation of fibronectin had occurred in some burn wound fluid samples, in which case intact fibronectin molecules were undetectable, and the largest fibronectin fragment was 116 kDa. The 116-kDa fragment as well as a smaller 90-kDa fragment contained the fibronectin cell binding domain. These burn-fluid samples degraded freshly added fibronectin. Activity of the fibronectin-degrading enzyme was blocked by a broad-spectrum serine proteinase inhibitor or by specific neutrophil elastase inhibitors but not by metalloproteinase inhibitors or inhibitors of trypsin-like or chymotrypsin-like serine proteinases. Enzyme activity also was neutralized by antibodies against human neutrophil elastase. Incubation of fibronectin with burn wound fluid or purified human neutrophil elastase generated similar fibronectin-degradation products. Finally, direct assay of burn-wound-fluid samples with a synthetic elastase substrate showed a correlation between fluid-phase elastase activity and fibronectin degradation. Based on these findings, we conclude that burn-wound-fluid elastase is responsible for extensive fibronectin degradation. Acute elevation of elastase did not appear to hinder normal wound repair.

Formation and structure of cross-linking and monomeric pyrrole autoxidation products in 2,5-hexanedione-treated amino acids, peptides, and protein

2,5-Hexanedione (2,5-HD) is the neurotoxic gamma-diketone metabolite of the industrial solvent n-hexane. Substantial evidence indicates that 2,5-HD reacts with neurofilament protein lysine epsilon-amines to yield 2,5-dimethylpyrrole adducts and that this reaction is critical to the mechanism of toxicity. Alkylpyrroles are susceptible to autoxidative dimerization, a process that has also been suggested as an obligatory step in 2,5-HD neuropathy. In the present study, we characterized pyrrole autoxidation products of a 2,5-HD-treated lysine analogue and of a model, lysine-containing dipeptide and examined mechanistic aspects of pyrrole-mediated protein cross-linking. Incubation of 2,5-HD with N alpha-acetyllysine or the dipeptide N alpha-acetylglycyllysine methyl ester in physiological buffer (pH 7.4) under oxidative conditions resulted in time-dependent formation of the N epsilon-pyrrole derivative and two major pyrrole autoxidation products, as demonstrated by HPLC, on-line thermospray MS, and UV photodiode array detection. An autoxidative pyrrole dimer containing a methylene bridge between C-2 of one pyrrole ring and C-3 of a second ring was characterized by thermospray MS and 1H-NMR spectroscopy. 13C-NMR spectroscopy provided evidence for an identical pyrrole-to-pyrrole bridge in autoxidized, pyrrolylated ribonuclease (RNase). MS analysis also revealed a second major product--a stable, oxygen-containing monomeric pyrrole derivative. This product exhibited a UV absorbance maximum (lambda max = 355 nm) consistent with extended conjugation. Polymerization of pyrrolylated acetyllysine was accelerated by persulfate, a free-radical initiator, and inhibited by ascorbate, an antioxidant.(ABSTRACT TRUNCATED AT 250 WORDS)