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)

Multiplanar variations in the structural characteristics of cancellous bone

A quantitative serial sectioning technique and a video-imaging procedure were used to obtain precise (20-microns voxels, in a 5 mm x 6 mm x 7 mm test volume) digital images of lumbar vertebral cancellous bone specimens. Conventional stereological image analyses were performed on this data to determine multiplanar (bulk) and surface planar variations in cancellous structural properties. Based upon an error analysis of subgroups of the complete serial planar images, our findings suggest that, for a plane resolution of 20 microns, sectioning at an increment < or = 100 microns along an axis is necessary to obtain accurate data of bulk structural properties of cancellous bone. Planar structural variations obtained from the serial sections of cancellous bone revealed a high degree of complexity and heterogeneity of the bone architecture. Bone area centers deviated from the section centroid and showed a helical variation along the primary or superior--inferior loading axis of samples. In comparison with the base planes (perpendicular to the superior-inferior axis), the lateral planes (parallel to the superior-inferior axis) of spine samples showed smaller mean values of structural indices and a more oriented structure. This structural anisotropy may be related to the functional mechanical anisotropy of the samples.

Regulation of tetrahydrobiopterin biosynthesis in cultured dopamine neurons by depolarization and cAMP

Primary cultures containing embryonic rat brain mesencephalic or hypothalamic dopamine neurons were used to examine the effects of membrane depolarization and elevations of cAMP levels on tetrahydrobiopterin cofactor content. Initial studies showed that 24-h incubations with 8-bromo-cAMP or isobutyl methylxanthine increased cofactor levels in either culture system, whereas the stimulatory effects of forskolin or depolarization of membrane potential were only observed in cultures of hypothalamus. 8-Bromo-cAMP was found to increase cofactor content in a concentration-dependent manner, with increases observed up to 5 mM. The time course of the effect of 8-bromo-cAMP was biphasic. Over the short term, an increase of 50% in cofactor content at 2 and 5 h was detected. Over the long term, by 24-48 h, cofactor levels increased by between 100% and 300%. Studies of cofactor turnover indicated that the long-term increase was due to stimulation of tetrahydrobiopterin biosynthesis with no alteration in degradation rate. Inhibitors of gene transcription and translation prevented the long- but not short-term increase in cofactor content. Levels of GTP cyclohydrolase I mRNA were increased 7-10-fold following 5 h of incubation with 8-bromo-cAMP. Tetrahydrobiopterin biosynthesis within cultured dopamine neurons of the hypothalamus and mesencephalon thus appears to be regulated by a cAMP-dependent mechanism involving enhanced gene expression of enzyme(s) involved in cofactor biosynthesis.

Effects of specimen load-bearing and free surface layers on the compressive mechanical properties of cellular materials

The influence of load-bearing surface layers on Young's modulus was determined for cancellous bone and polyurethane foam specimens of three different heights cut from each material: 16, 9, and 5 mm for bone specimens (cross-sectional area A = 81 mm2) ranging in density from 0.04 to 0.32 g cm-3; 20, 10, and 5 mm for foam specimens (A = 100 mm2) ranging in density from 0.064 to 0.64 g cm-3. The compressive elastic modulus of the 5 mm bone specimens was significantly smaller (42%) than that of the 16 mm bone specimens. A similar change in elastic modulus was also observed for the foam specimens, but the height effect diminished in a relatively linear manner as the foam density increased. For a height change from 20 to 5 mm, the foam modulus difference ranged from a 41% decrease for the lowest density specimens (p = 0.064 g cm-3) to an insignificant change (< 1.8%) for the highest foam density specimens (p = 0.64 g cm-3). The specimen height effect on elastic modulus was hypothesized to result from a higher deformation (compliance) of the cellular materials in the load-bearing or contacting surface layer than in the bulk. A mathematical formula was derived to predict the variation in measured elastic modulus (E) caused by the contacting surface layer modulus (Ecs) to bulk modulus (Eb) ratio (Y = Ecs/Eb) and contacting surface layer height (hcs) to sample height (h) ratio (t = hcs/h): E/Eb = Y/[Y(1-t)+t]. Predicted differences in the measured modulus associated with graduated specimen heights were verified experimentally by regional strain measurements of the foam and bone samples using an optical microscope. The influence of free-surface layers was also determined for the foam specimens with cross-sectional areas 1.21 and 10 times the load-bearing area of a load platen, but the measured differences were small (< 10%) compared to that of the load-bearing surface layer influence. In future compressive mechanical testing of cellular materials, specimens < 10 mm in height should be avoided, particularly specimens with low bulk density or high porosity.

[Effects of "moist burn ointment--mei bao" on production of IL-2 in burn rats and its clinical problems]

Since "Mei Bao" has been used in clinical treatment of burn wounds, there is a diversity of opinions concerning its effect. We carried out a series of experiments to observe its therapeutic effect, bacteriostatic property, and its effect on production of IL-2 in thermally injured rats. These results indicate that obvious infection occurred after its use on burn wounds and healing is delayed. Hyperplastic scars accompanying with deformity appeared after healing. The cost of treatment is high. There is no improvement in immune reaction, and no bacteriostatic property is observed.

The value of hepatitis B x antigen as a prognostic marker in the development of hepatocellular carcinoma

Chronic infection with hepatitis-B virus (HBV) is associated with high risk for the development of hepatocellular carcinoma (HCC). Several studies have implicated that the X gene product(s) of HBV are important to the pathogenesis of HCC. This study tests the hypothesis that immunohistochemical detection of hepatitis B x antigen (HBxAg) is closely associated with HCC. The patterns of HBxAg were determined by staining in tumor and non-tumor liver sections from 30 Chinese patients with HBV-associated HCC, and the results were compared with other markers of infection. HBxAg was the most prevalent marker of HBV infection both in tumor and in non-tumor tissues of HCC patients, as compared with the hepatitis-B surface and core antigens. This pattern was observed among carriers as well as several patients who were HBsAG- in serum. The HBxAg staining results were validated by Southern blotting with an X-region probe and by Western blotting with anti-HBx. These results suggest that the persistence of HBxAg is important to the pathogenesis of early HCC and that HBxAg expression in the liver during chronic HBV infection may be an important prognostic marker for the development of HCC.

Capillary electrophoresis of abnormal hemoglobins associated with alpha-thalassemias

Capillary electrophoresis was evaluated for separation of hemoglobin species associated with alpha-thalassemias, and for identification of hemoglobin variants commonly found in the same human populations. Separation of hemoglobins was achieved using capillary isoelectric focusing with chemical mobilization; visible-wavelength absorbance detection was used to identify hemoglobins against a background of nonheme-containing proteins. This technique could easily differentiate hemoglobins Bart's and H (associated with alpha-thalassemias) from hemoglobin variants. Analysis of globin chains derived from intact hemoglobins was performed by free zone capillary electrophoresis under denaturing conditions. This technique was useful for distinguishing Hb Bart's and Hb H, and for confirming the identity of hemoglobin variants.

Detection of the actin scavenger system in burn wound fluid

The intravascular actin scavenger system depolymerizes and sequesters actin released after tissue injury. Studies were carried out to determine if this system is active in the extracellular space during wound repair. Using burn wound fluid as a noninvasive means for analyzing the wound environment, we measured actin accumulation and actin complex formation with the plasma proteins responsible for scavenger function. Actin at concentrations as high as 0.25 mg/ml ( approximately 5 micromol/L) was found in burn wound fluid samples from 9 of 11 patients. Wound fluid also contained the two plasma proteins that bind actin-gelsolin (both plasma and cytoplasmic forms) and Gc protein. Because actin in wound fluid was complexed with gelsolin and Gc protein, we conclude that the components of the actin scavenger system are functional in wound tissue. In addition, proteolysis of gelsolin, but not actin or Gc protein, appeared to occur at the wound site. Gelsolin proteolysis was accompanied by the appearance of 49 kd gelsolin fragments, and wound fluid samples lacking intact gelsolin also contained high metalloproteinase levels.

Hepatitis B x antigen and p53 are associated in vitro and in liver tissues from patients with primary hepatocellular carcinoma

To test the hypothesis that hepatitis B x antigen (HBxAg) binds to the tumor-suppressor protein p53, immunoprecipitation was carried out with monoclonal anti-x or monoclonal anti-p53 using radiolabeled HBxAg and p53 made by in vitro translation. The results showed that anti-p53 specifically immunoprecipitates HBxAg only in the presence of p53 and that anti-x specifically immunoprecipitates p53 only in the presence of HBxAg. to determine whether HBxAg binds p53 in vivo, immunoprecipitation and Western blot analysis of liver samples from 10 hepatitis B virus (HBV)-infected patients with primary hepatocellular carcinoma (PHC) were carried out. A protein band at 53,000 daltons that specifically immunoprecipitated with a monoclonal anti-x was identified as p53 by Western blotting with a monoclonal anti-p53. Anti-p53 specifically immunoprecipitated bands of 28,000, 17,000 and 13,000 daltons, which were identified as HBxAg polypeptides by Western blotting with anti-HBx. These findings suggest that HBxAg binds to p53 and that this association is important to the development of PHC.

Beyond Section 504: satisfaction and empowerment of students with disabilities in higher education

College and university students with disabilities were surveyed to determine their levels of satisfaction with accessibility, special services, and accommodations at their schools. In addition, students were requested to identify barriers to postsecondary education, improvements in services, and other concerns. Respondents generally expressed satisfaction with the services that they had received. However, the majority indicated that they had encountered barriers to their education, including a lack of understanding and cooperation from administrators, faculty, staff, and other students; lack of adaptive aids and other resources; and inaccessibility of buildings and grounds. Recommendations were made for improving the delivery of services and self-advocacy of students with disabilities.

Effects of some opiates and opioid peptide eyedrops on ocular melatonin regulation in rabbits

Levels of melatonin in rabbit eye tissues were detected by radioimmunoassay. Solutions of met-enkephalin, leu-enkephalin, alpha-endorphin and beta-endorphin were given topically. Met-Enkephalin and alpha-endorphin lowered levels of melatonin in the iris, iris root-ciliary body, retina and choroid; leu-enkephalin raised levels in the retina and lowered them in other tissues. beta-Endorphin only lowered levels in the iris root-ciliary body. DAGO (a mu agonist) given i.v. lowered levels of melatonin in the iris, iris root-ciliary body and retina. The delta and sigma agonists given i.v. only lowered levels in the iris root-ciliary body, and a kappa agonist given i.v. raised levels in the ciliary body. No opiate binding sites could be detected in the rabbit iris or iris root-ciliary body for any class of receptor. Our data suggest opioids may be useful for treating glaucoma.

Differential metabolism of tetrahydrobiopterin in monoamine neurons: a hypothesis based upon clinical and basic research

This chapter has attempted to describe and integrate some of the clinical and basic research that support our hypothesis that the metabolism of BH4 is normally heterogeneous across different populations of monoamine-containing neurons. Based upon this hypothesis, there may now be reason to support the idea that certain neuropsychiatric illnesses, which are though to be the result (at least in part) of altered monoamine metabolism, might find their roots in an abnormal metabolism of BH4 within specific monoaminergic cell groups. Such a specific dysfunction might not be apparent in the rest of the brain or peripheral nervous system, thereby being difficult to detect. Perhaps the application of molecular biological techniques to studies of BH4 metabolism in man will shed new light on these problems.

Analysis of alkylpyrrole autoxidation products by high-performance liquid chromatography with thermospray mass spectrometry and UV photodiode-array detection

A method employing high-performance liquid chromatography with thermospray mass spectrometry (TSP-MS) and photodiode-array detection was developed and applied to the analysis of autoxidation products of 2,5-dimethyl-N-alkylpyrroles in aqueous solution under air or 18O2. Numerous oxidation products were separated, characterized and categorized, primarily as (1) non-polar oligomers without incorporated oxygen, and (2) polar, oxygen-containing monomers. Kinetic studies showed that oligomerization was the dominant autoxidation pathway, with production of unstable dimers and trimers and, ultimately, a high-molecular-mass sediment. TSP-MS together with UV and proton nuclear magnetic resonance spectral data revealed that both the dimer and trimer contained a novel methylene bridge. These results suggest that this method is suitable for the analysis of alkylpyrrole autoxidation products that may be relevant to hexane neuropathy and products that are responsible for the instability of fuels in storage.

Direct measurement of oxygen free radicals following cardiac failure of ischemic dog myocardium with the electron spin resonance technique

OBJECTIVE

To determine whether the involvement of oxygen-derived free radicals in the pathogenesis of ischemic cardiac failure in dogs.

DESIGN

Free radicals were measured in normal and ischemic myocardium from dogs with cardiac failure induced by acute coronary occlusion. The changes in free radical production in ischemic myocardium (compared with normal myocardium with or without polymorphonuclear leukocytes) were studies, with plasma superoxide dismutase and malondialdehyde analyzed concurrently.

MAIN RESULTS

The results showed that the oxygen free radicals in the ischemic myocardium were about 42.5% higher than those in the normal myocardium, about 67.8% higher than those in the normal myocardium washed with normal saline and about 60.5% higher than those in the ischemic myocardium washed with normal saline (P < 0.05). Compared with controls, the concentration of malondialdehyde in ischemic dog myocardium was increased markedly. The activity of plasma superoxide dismutase was not significantly different between control dogs and dogs with ischemic cardiac failure.

CONCLUSIONS

The current results indicate that there was increased production of free radicals and peroxidative damage in ischemic myocardium of dogs with cardiac failure. Polymorphonuclear leukocytes appear to be a main source of free radicals in dog with ischemic cardiac failure.

[Isolation of Neisseria from human dental plaque and study of characteristics of acid degradation]

The Neisseria was isolated and identified from human dental plaque.The incidence of Neisseria was 100%.The N.Sicca was the predominant group.The results of sugar metabolism of Neisseria indicated that they were not only able to produce acid while sugar was offered sufficiently,but also degrade lactate evenacetate to supply energy after sugar was consumed.