Two-step high resolution sequence-based HLA-DRB typing of exon 2 DNA with taxonomy-based sequence analysis allele assignment

A two-step high resolution sequence-based DRB typing method was developed. The system needs only one polymerase chain reaction (PCR) to type all functional DRB alleles of a given individual. It uses a pair of generic PCR primers to amplify exon 2 DNA of all functional DRB genes and a first-step taxonomy-based sequence analysis (FSTBSA) method to assign allele groups after sequencing the PCR products with a generic primer. In the second step, group-specific primers are used to sequence the same PCR products and a taxonomy-based sequence analysis (TBSA) is used to assign alleles. Thus, both low and high resolution DRB typing can be done with PCR amplified exon 2 DNA from a single PCR reaction. Correct allele group assignment by FSTBSA was confirmed by sequencing the PCR products with group-specific primers and correctly assigned all 158 DNA samples including 34 samples pre-typed by PCR-sequence-specific primer or PCR-sequence-specific oligonucleotide probe. FSTBSA correctly assigned 116 heterozygous combinations of 81 DRB1-DRB3/4/5 haplotypes. Sixty-seven DRB1, 6 DRB3, 1 DRB4, and 3 DRB5 alleles were identified in this study. TBSA successfully resolved all heterozygous allele combinations including 31 heterozygous combinations of 33 alleles of DRB1*03, 08, 11, 12, 13, and 14 allele groups, and six heterozygous combinations of six DRB3 alleles.

The crystal structure of the influenza matrix protein M1 at neutral pH: M1-M1 protein interfaces can rotate in the oligomeric structures of M1

The influenza matrix protein (M1) forms a protein layer under the viral membrane and is essential for viral stability and integrity. M1 mediates the encapsidation of the viral RNPs into the viral membrane by its membrane and RNP-binding activities. In order to understand the roles of M1-M1 protein interactions in forming the M1 layer, X-ray crystallographic studies of a M1 fragment (1-162) were carried out at neutral pH and compared with an acidic pH structure. At neutral pH the asymmetric unit was a stacked dimer of M1. A long molecular ribbon of neutral stacked dimers was formed by translation as dictated by the P1 space group. The elongated ribbon had a positively charged stripe on one side of the ribbon. A similar M1-M1 stacking interface was also found in the acidic asymmetric unit. However, within the acidic stacked dimer the molecules were not straight, but rotated in relation to each other by slightly changing the M1-M1 stacking interface. The acidic structure possessed an additional M1-M1 twofold interface. Protein docking confirmed that the M1-M1 stacking and M1-M1 twofold interfaces could be used to form a double ribbon of M1 molecules. By iterative repetition of the rotated relationship among the M1 molecules, a helix of M1 was generated. These studies suggest that M1 has the ability to form straight or bent elongated ribbons and helices. These oligomers are consistent with previous electron microscopic studies of M1, which demonstrated that isolated M1 formed elongated and flexible ribbons when isolated from what appeared to be a helical shell of M1 in the influenza virus.

[Analysis and experimental study of reasons for breakage in the bone fracture plate during internal fixation]

Bone fracture plate has been in clinical use for internal fixation of fracture, however, during healing, the steel plate breaks occasionally. This paper applied the static strength theory to imitate the pressed down combination out of shape that was borne by single limb of human body standing. Fracture was made on low limbs of the fresh dead body, fixed with a bone fracture plate. Strain measure was made on a bone fracture plate. Additionally, fatigue experiment and four-point bending experiment were carried out on a bone fracture plate. The reason for a breakage in the bone fracture plate was analyzed with static strength theory and low period fatigue theory.

Differentiation of NIH3T3 fibroblasts into adipocytes induced by peroxisome proliferator activated receptor gamma 2 expression

OBJECTIVE

To express mouse peroxisome proliferator activated receptor gamma 2 (mPPAR gamma 2) in NIH3T3 fibroblasts mediated by the recombinant retrovirus and study its function.

METHODS

The mPPAR gamma 2 gene was subcloned into retrovirus vector pGCEN to generate the recombinant pGCEN/mPPAR gamma 2. Then it was packaged into PA317 cells and selected with G418. Viral supernatants were harvested and then used to infect NIH3T3 fibroblasts. PPAR gamma activator 5, 8, 11, 14-eicosatetraynoic acid (ETYA) was used to induce the mPPAR gamma 2-expressing NIH3T3 cells into adipocyte differentiation.

RESULTS

The recombinant retrovirus pGCEN/mPPAR gamma 2 was constructed, and the higher titers of the viral supernatants were obtained. mPPAR gamma 2 was expressed in NIH3T3 cells mediated by the recombinant retrovirus. Lipid accumulation obviously existed in these induced adipocytes which morphologically resembled mature adipocytes in vivo and expressed tissue specific adipocyte P2 (AP2) and Leptin genes.

CONCLUSIONS

An adipocyte differentiation model in vitro was successfully established. The work is the basis for further research on the molecular mechanism of adipocyte differentiation induced by PPAR gamma 2.

An avian basal ganglia pathway essential for vocal learning forms a closed topographic loop

The mammalian basal ganglia-thalamocortical pathway is important for motor control, motor learning, and cognitive functions. It contains parallel, closed loops, at least some of which are organized topographically and in a modular manner. Songbirds have a circuit specialized for vocal learning, the anterior forebrain pathway (AFP), forming a basal ganglia loop with only three stations: the pallial ("cortex-like") lateral magnocellular nucleus of the anterior neostriatum (lMAN), the basal ganglia structure area X, and the medial portion of the dorsolateral thalamic nucleus (DLM). Several properties of this pathway resemble those of its mammalian counterpart, but it is unknown whether all projections in the loop are topographically organized, and if so, whether topography is maintained through the entire loop. After small single- or dual-tracer injections into area X and/or the lMAN of adult zebra finches, we found that the area X to DLM projection is topographically organized, and we confirmed the topography for all other AFP projections. Quantitative analysis suggests maintained topography throughout the loop. To test this directly, we injected different tracers into corresponding areas in lMAN and area X. We found somata retrogradely labeled from lMAN and terminals anterogradely labeled from area X occupying the same region of DLM. Many labeled somata were tightly surrounded by tracer-labeled terminals, indicating the microscopically closed nature of the AFP loop. Thus, like mammals, birds have at least one closed, topographic loop traversing the basal ganglia, thalamus, and pallium. Each such loop could serve as a computational unit for motor or cognitive functions.

[An AFLP marker related to fibrogenesis in upland cotton (Gossypium hirsuturm L.)]

By using AFLP technique polymorphism analysis was performed between a fuzzlesslintless mutant line and its isogenic wild-type line, Xuzhou 142. Out of 6,360 bands produced by 64 pairs primers, a fragment, named as CF1, appearing stably in wild-type line, Xuzhou 142. This polymorphism was further verified using several normal fiber varieties and F2, F3 populations from the cross of fuzzless-lintless mutant line with a high-lint-percentage variety Yumian No. 1. The cosegregation of CF1 and fibrogenesis was proved, which suggested that CF1 can be used as a molecular marker for cotton fibrogenesis. The CF1 segment was cloned into PUCm-T Vector and then sequenced. The putative amino acid sequences, is an analogue to phenol hydroxylase alpha subunit, outer surface protein C, NADH dehydrogenase subunit 1, NADH-ubiquinone oxidoreductase, 2-oxoacid ferredoxin oxidoreduct and hypothetical 14.5kD protein.

Hadronic loop corrections to the muon anomalous magnetic moment

The dominant theoretical uncertainties in both the anomalous magnetic moment of the muon and the value of the electromagnetic coupling at the Z scale, M(Z), arise from their hadronic contributions. Since these will ultimately dominate the experimental errors, we study the correlation between them, as well as with other fundamental parameters. To this end we present analytical formulas for the QCD contribution from higher energies and from heavy quarks. Including these correlations affects the Higgs boson mass extracted from precision data.

Study of an Au colloid self-assembled electrode and its application to the determination of carbon monoxide

A novel electrochemical sensor has been developed for the detection of carbon monoxide. The chemically modified electrode, prepared by reaction of cysteine and then an Au colloid of size approximately 15 nm with a platinum microelectrode, has excellent catalytic activity toward carbon monoxide, with an oxidation potential of +600 mV relative to the Ag/AgCl electrode. The CO gas sensor is based on an Au colloid self-assembled modified electrode as working electrode, an Ag/AgCl electrode as reference electrode, a Pt electrode as counter electrode, and a porous film which is in direct contact with the gas-containing atmosphere. The effects on the determination of CO of different internal electrolyte solutions of perchloric acid, hydrochloric acid, sulfuric acid, nitric acid, and phosphate buffer of different concentrations were also studied. The sensor is characterized by a short response time and highly reproducible detection of CO. This sensor can be used in the field of environmental monitoring and control.

RANTES-induced chemokine cascade in dendritic cells

Dendritic cells (DC) are the most potent APCs and the principal activators of naive T cells. We now report that chemokines can serve as activating agents for immature DC. Murine bone marrow-derived DC respond to the CC chemokine RANTES (10-100 ng/ml) by production of proinflammatory mediators. RANTES induces rapid expression of transcripts for the CXC chemokines KC and macrophage inflammatory protein (MIP)-2, the CC chemokines MIP-1beta and MIP-1alpha, and the cytokines TNF-alpha and IL-6. Synthesis of KC, IL-6, and TNF-alpha proteins were also demonstrated. After 4 h, autoinduction of RANTES transcripts was observed. These responses are chemokine specific. Although DC demonstrated weak responses to eotaxin, DC failed to respond to other chemokines including KC, MIP-2, stromal-derived factor-1alpha, MIP-1beta, MIP-1alpha, monocyte chemoattractant protein-1, T cell activation gene 3, or thymus-derived chemotactic agent 4. In addition, RANTES treatment up-regulated expression of an orphan chemokine receptor termed Eo1. Chemokine induction was also observed after treatment of splenic DC and neonatal microglia with RANTES, but not after treatment of thymocytes or splenocytes depleted of adherent cells. TNF-alpha-treated DC lose responsiveness to RANTES. DC from mice deficient for CCR1, CCR3, and CCR5 respond to RANTES, indicating that none of these receptors are exclusively used to initiate the chemokine cascade. RANTES-mediated chemokine amplification in DC may prolong inflammatory responses and shape the microenvironment, potentially enhancing acquired and innate immune responses.

Fruit development is actively restricted in the absence of fertilization in Arabidopsis

Flowering plants usually require fertilization to form fruit and seed and to initiate floral organ abscission in structures that do not contribute to the fruit. An Arabidopsis mutant that initiates seedless fruit without fertilization (fwf) or parthenocarpy was isolated and characterized to understand the factors regulating the transition between the mature flower and the initiation of seed and fruit development. The fwf mutant is fertile and has normal plant growth and stature. It sets fertile seed following self-pollination and fertilization needs to be prevented to observe parthenocarpy. The initiation of parthenocarpic siliques (fruit) was found to be dependent upon carpel valve identity conferred by FRUITFULL but was independent of the perception of gibberellic acid, shown to stimulate parthenocarpy in Arabidopsis following exogenous application. The recessive nature of fwf is consistent with the involvement of FWF in processes that inhibit fruit growth and differentiation in the absence of fertilization. The enhanced cell division and expansion in the silique mesocarp layer, and increased lateral vascular bundle development imply FWF has roles also in modulating silique growth post-fertilization. Parthenocarpy was inhibited by the presence of other floral organs suggesting that both functional FWF activity and inter-organ communication act in concert to prevent fruit initiation in the absence of fertilization.

[Study on inhibitory effect of ampelopsin on melanoma by serologic pharmacological method]

OBJECTIVE

To study the inhibitory effect of ampelopsin on melanoma.

METHODS

Using a serologic pharmacological method, the inhibitory effects of different dose of ampelopsin on B16 melanoma cells were evaluated by a MTT assay and a flow cytometry.

RESULTS

The serums of C57BL/6 mices, which were administered by 0.420 mmol/kg dose and 0.560 mmol/kg dose of ampelopsin, could obviously suppress the B16 melanoma cells, and the inhibitory rate was equal to that of the vacant serum adding same consistency ampelopsin. The drug serums of the two doses groups reduced the cleavage and proliferation index of B16 melanoma cells to 19.1% and 21.7% respectively.

CONCLUSION

Ampelopsin possibly acts on melanoma B16 cells by original form drug at the period with a peak of the drug concentration, and inhibits the DNA synthesis of B16 cells.

A genome-wide search for type II diabetes susceptibility genes in Chinese Hans

AIMS/HYPOTHESIS

The aim of the study was to search for Type II (non-insulin-dependent) diabetes mellitus susceptibility genes in a Chinese population.

METHODS

A genome-wide scan was carried out using non-parametric linkage analyses. We studied 102 families (478 family members) who were Chinese Hans residing in east and south-east China, including 282 diabetic patients, among them 142 independent affected sibpairs were available for genotyping. A total of 247 fluorescence labelled microsatellite markers, with an average resolution of 15 cM, were amplified. GENEHUNTER was used for the non-parametric linkage analyses.

RESULTS

Two loci on chromosome 9 D9S171 and D9S175 showed suggestive evidence for linkage, with an NPL-score of 3.286 and 2.939 respectively, and a p value of 1.19 x 10(-4) and 4.47 x 10(-4). A locus on the long arm of chromosome 20, D20S196 showed a rise in the non-parametric-linkage score (from 1.517 to 2.922) and a corresponding decrease in the p value from 0.04 to 6.5 x 10(-4) when families with lower BMI were analysed alone. Other loci with weaker evidence for linkage were also observed.

CONCLUSIONS

Our results suggest that chromosome 9 contains genes involved in the susceptibility to Type II diabetes in an eastern and southeastern Chinese Han population, and chromosome 20 could hide genes linked to Type II diabetes in families with a lower BMI. Other regions could also hide susceptibility genes with minor effects.

[Adipocytes differentiation of NIH3T3 cells induced by peroxisome proliferator activation receptor gamma 2 expression]

OBJECTIVE

To express the mouse peroxisome proliferator activated receptor gamma 2(mPPAR gamma 2) in NIH3T3 cells mediated by the recombinant retrovirus and study its function.

METHODS

mPPAR gamma 2 gene digested from the recombinant plasmid pcDNA3/mPPAR gamma 2 and confirmed to contain the target gene segment with fluorescence-sequencing was subcloned into retrovirus vector pGCEN to generate the recombinant retrovirus pGCEN/mPPAR gamma 2. The recombinant retrovirus pGCEN/mPPAR gamma 2 and pGCEN were packaged with PA317 cells and anti-G418 clones of PA317 cells were selected. Viral supernatants were collected and used to infect NIH3T3 cells. Peroxisome proliferator activated receptor gamma 2 (PPAR gamma 2)-expressing NIH3T3 cells cultured in the differentiation media containing PPAR gamma activator ETYA were induced into adipocytes.

RESULTS

The recombinant retrovirus pGCEN/mPPAR gamma 2 was constructed, 5 x 10(4) CFU/ml of the viral supernatants containing pGCEN/mPPAR gamma 2 and 6 x 10(5) CFU/ml of the viral supernatants containing pGCEN were obtained. mPPAR gamma 2 was expressed in NIH3T3 cells mediated by the recombinant retrovirus. Lipid accumulation obviously existed in PPAR gamma 2-expressing NIH3T3 cells at 10 days postdifferentiation and the lipid-containing cells morphologically resembled the mature adipocytes in vivo.

CONCLUSION

An adipocyte differentiation model in vitro was established. The work is the basis for further researches on the molecular mechanism of adipocyte differentiation induced by PPAR gamma 2.

Melon bacterial artificial chromosome (BAC) library construction using improved methods and identification of clones linked to the locus conferring resistance to melon Fusarium wilt (Fom-2)

Utilizing improved methods, two bacterial artificial chromosome (BAC) libraries were constructed for the multidisease-resistant line of melon MR-1. The HindIII library consists of 177 microtiter plates in a 384-well format, while the EcoRI library consists of 222 microtiter plates. Approximately 95.6% of the HindIII library clones contain nuclear DNA inserts with an average size of 118 kb, providing a coverage of 15.4 genome equivalents. Similarly, 96% of the EcoRI library clones contain nuclear DNA inserts with an average size of 114 kb, providing a coverage of 18.7 genome equivalents. Both libraries were evaluated for contamination with high-copy vector, empty pIndigoBac536 vector, and organellar DNA sequences. High-density filters were screened with two genetic markers FM and AM that co-segregate with Fom-2, a gene conferring resistance to races 0 and 1 of Fusarium wilt. Fourteen and 18 candidate BAC clones were identified for the FM and AM probes, respectively, from the HindIII library, while 34 were identified for the AM probe from filters A, B, and C of the EcoRI library.

Galanin transgenic mice display cognitive and neurochemical deficits characteristic of Alzheimer's disease

Galanin is a neuropeptide with multiple inhibitory actions on neurotransmission and memory. In Alzheimer's disease (AD), increased galanin-containing fibers hyperinnervate cholinergic neurons within the basal forebrain in association with a decline in cognition. We generated transgenic mice (GAL-tg) that overexpress galanin under the control of the dopamine beta-hydroxylase promoter to study the neurochemical and behavioral sequelae of a mouse model of galanin overexpression in AD. Overexpression of galanin was associated with a reduction in the number of identifiable neurons producing acetylcholine in the horizontal limb of the diagonal band. Behavioral phenotyping indicated that GAL-tgs displayed normal general health and sensory and motor abilities; however, GAL-tg mice showed selective performance deficits on the Morris spatial navigational task and the social transmission of food preference olfactory memory test. These results suggest that elevated expression of galanin contributes to the neurochemical and cognitive impairments characteristic of AD.

[The genetic effect of estrogen receptor(ESR) on litter size traits in pig]

Litter size is one of the most important economic traits in pig production, and the more piglet numbers per litter is capable to increase pork production and bring more economic profit for pig industry. ESR (estrogen receptor) gene has been determined to be one of the major genes affecting phenotype of litter size without any genetic negative correlation to growth and carcass traits. An optimized standard PCR-RFLP protocol is employed to type 262 sows from 5 different breeds in ESR loci, and then with the computation based on linear model ESR gene is confirmed to be a major locus significantly associated with litter size (P < 0.001). The genetic effect of ESR gene is quite large in these breeds, especially in these Chinese pig population. The sows of beneficial homozygote BB produce 1.40-3.37 total number born/litter and 0.63-3.58 number born alive/litter more than the sows of non-beneficial homozygote AA do. The information found in the present study is very important and could be utilized as DNA marker for improvement of reproduction trait in practice of pig breeding.

[The normalization creep functions of C5.6,T6.7,L4.5 interverbral discs of human vertebral column]

In this paper are reported the creep experimental studies on 9 fresh C5.6 intervertebral discs,9 fresh T6.7 intervertebral discs and 10 L4.5 intervertebral discs that were taken from the bodies of ten men(aged 19-35 years) who had died of head injury 1-4 h before. By simulating the temperature of human body (36.5 degrees C +/- 0.5 degree C) and putting 300 N load on the discs, we measured the intervertebral creep effects and obtained the strain-time curves.

[Effects of hypothyroidism on Goalpha gene expression in hippocampus and dentate gyrus during early development of rat brain]

AIM

To study the expression of Goalpha mRNA in hippocampus and dentate gyrus of 7-day rats with hypothyroidism.

METHODS

We use wistar rat model of hypothyroidism and non-radioactive in situ hybridization technique to observe the changs of Goalpha mRNA levels in hippocampus and dentate gyrus of 7-day rats with or without hypothyroidism.

RESULTS

Perinatal hypothyroidism can increase Goalpha mRNA levels in all areas of hippocampus and dentate gyrus of 7-day rats.

CONCLUSION

Thyroid hormone can down-regulate Goalpha gene transcription in hippocampus and dentate gyrus during the early development of rat brain.

Identification of a novel DRB1 allele, DRB1*1112, by sequence-based DRB typing

We report here a novel DRB1 allele (DRB1*1112) identified during sequence-based HLA-DRB typing. Polymerase chain reaction with generic DRB primers and group-specific primers and subsequent sequencing yielded identical results. Molecular cloning and sequencing confirmed that the new DRB1 allele is identical to DRB1*11011 and 1129 at exon 2 except for a single nucleotide substitution at codon 37, changing the codon from Tyr (DRB1*11011) or Ser (DRB1*1129) to Phe.

Human immunodeficiency virus type 1-infected women exhibit reduced interferon-gamma secretion after Chlamydia trachomatis stimulation of peripheral blood lymphocytes

Epidemiologic, animal, and in vitro models suggest an important role for interferon (IFN)-gamma in the clearance of Chlamydia trachomatis infection. IFN-gamma in the supernatants of in vitro-stimulated peripheral blood mononuclear cells (PBMC) from 22 human immunodeficiency virus type 1 (HIV-1)-infected and 73 uninfected women at high risk for C. trachomatis acute pelvic inflammatory disease (PID) was studied. PBMC were stimulated with C. trachomatis purified major outer membrane protein (MOMP) and whole elementary bodies (EBs) from the 4 predominant serovars (E, F, K, and L2) that circulate in Nairobi. PBMC IFN-gamma secretion after stimulation with C. trachomatis EBs was significantly decreased in HIV-1-infected women. Among HIV-1-infected women, CD4 T cell depletion was associated with lower IFN-gamma secretion from PBMC stimulated with either C. trachomatis MOMP or EB antigen. Decreased antigen-specific IFN-gamma production may enhance the susceptibility of HIV-1-infected women to C. trachomatis PID.

Study of the assembly of vesicular stomatitis virus N protein: role of the P protein

To derive structural information about the vesicular stomatitis virus (VSV) nucleocapsid (N) protein, the N protein and the VSV phosphoprotein (P protein) were expressed together in Escherichia coli. The N and P proteins formed soluble protein complexes of various molar ratios when coexpressed. The major N/P protein complex was composed of 10 molecules of the N protein, 5 molecules of the P protein, and an RNA. A soluble N protein-RNA oligomer free of the P protein was isolated from the N/P protein-RNA complex using conditions of lowered pH. The molecular weight of the N protein-RNA oligomer, 513,879, as determined by analytical ultracentrifugation, showed that it was composed of 10 molecules of the N protein and an RNA of approximately 90 nucleotides. The N protein-RNA oligomer had the appearance of a disk with outer diameter, inner diameter, and thickness of 148 +/- 10 A, 78 +/- 9 A, and 83 +/- 8 A, respectively, as determined by electron microscopy. RNA in the complexes was protected from RNase digestion and was stable at pH 11. This verified that N/P protein complexes expressed in E. coli were competent for encapsidation. In addition to coexpression with the full-length P protein, the N protein was expressed with the C-terminal 72 amino acids of the P protein. This portion of the P protein was sufficient for binding to the N protein, maintaining it in a soluble state, and for assembly of N protein-RNA oligomers. With the results provided in this report, we propose a model for the assembly of an N/P protein-RNA oligomer.

Expression and parent-of-origin effects for FIS2, MEA, and FIE in the endosperm and embryo of developing Arabidopsis seeds

The promoters of MEA (FIS1), FIS2, and FIE (FIS3), genes that repress seed development in the absence of pollination, were fused to beta-glucuronidase (GUS) to study their activity pattern. The FIS2GUS product is found in the embryo sac, in each of the polar cell nuclei, and in the central cell nucleus. After pollination, the maternally derived FIS2GUS protein occurs in the nuclei of the cenocytic endosperm. Before cellularization of the endosperm, activity is terminated in the micropylar and central nuclei of the endosperm and subsequently in the nuclei of the chalazal cyst. MEAGUS has a pattern of activity similar to that of FIS2GUS, but FIEGUS protein is found in many tissues, including the prepollination embryo sac, and in embryo and endosperm postpollination. The similarity in mutant phenotypes; the activity of FIE, MEA, and FIS2 in the same cells in the embryo sac; and the fact that MEA and FIE proteins interact in a yeast two-hybrid system suggest that these proteins operate in the same system of control of seed development. Maternal and not paternal FIS2GUS, MEAGUS, and FIEGUS show activity in early endosperm, so these genes may be imprinted. When fis2, mea, and fie mutants are pollinated, seed development is arrested at the heart embryo stage. The seed arrest of mea and fis2 is avoided when they are fertilized by a low methylation parent. The wild-type alleles of MEA or FIS2 are not required. The parent-of-origin-determined differential activity of MEA, FIS2, and FIE is not dependent on DNA methylation, but methylation does control some gene(s) that have key roles in seed development.

Changes of reliability and efficiency of micronucleus bioassay in Vicia faba after exposure to metal contamination for several generations

Mitotic root micronucleus (MCN) frequency in Vicia faba as a bioassay, is primarily based on the extent of the sentinel Vicia response in terms of cytogenetic damage quantitatively or qualitatively to indicate the presence of mutagenic contaminants. This paper describes an investigation designed to assess changes in MCN frequencies of Vicia faba from three generation plants obtained, respectively from a reference site (RS) and a metal-contaminated experimental field (EF) in the bioassay of mutagenic Cd(2+) and NaN(3). The background value, dose-response to Cd(2+) and to NaN(3) in three generation (F(1), F(2) and F(3)) plants of the EF and the initial (F(0)) plants were determined in terms of MCN frequencies. With more generations of growing Vicia plants in the EF, a higher background value of MCN frequency, a lower slope value in the regression equation, a smaller ratio of MCN frequency between the control and treatment in the same generation and larger perturbation values were observed. This denotes that the decreased reliability and efficiency are represented in Vicia plants from the EF if the plants are used as sentinels in the bioassay of mutagenic Cd(2+) and NaN(3). It was concluded that the Vicia MCN bioassay should be used as an endpoint biomarker acceptable in biomonitoring environmental mutagens when the sentinel plants were collected from clean areas. Because no place is absolutely without pollutants, it is suggested that several seed stock centers should be established for providing sentinel Vicia if Vicia MCN bioassay is used as a biomarker to identify the global environmental status.

Genome organization and phylogenetic distribution of a novel family of ancient murine endogenous proviruses with evidence for transposition-mediated proliferation

A new family of murine endogenous proviruses (VL6.0) is described here. The intact provirus is near 6 kb in length and shows a genomic organization of 5' LTR, gag, pol, env, and 3' LTR. The primer binding site (PBS) is that of a tRNA(gly). The lack of functional open reading frames and occurrence of significant gaps in most, if not all, members of this group show it to be ancient. Our estimate of copy number per haploid genome is 30+. Members of this group have been isolated from Mus musculus domesticus, M. m. casteneus, M. m. hortulanus, M. caroli, and M. spretus. The occurrence of these sequences throughout such diverse members of the genus Mus may indicate that the date of the original infection predated the divergence of the extant Mus lineages at around 2.5 million years ago. Analysis of gap (deletion/insertion) patterns indicates that these sequences may have proliferated within the Mus genome by a mechanism of reverse transcriptase-mediated transposition. As yet, there are no closely related murine retroviruses described. The closest mammalian retrovirus based on sequence similarity is from the miniature swine (Sus scrofa).

A novel murine Staufen isoform modulates the RNA content of Staufen complexes

Mouse Staufen (mStau) is a double-stranded RNA-binding protein associated with polysomes and the rough endoplasmic reticulum (RER). We describe a novel endogenous isoform of mStau (termed mStau(i)) which has an insertion of six amino acids within dsRBD3, the major double-stranded RNA (dsRNA)-binding domain. With a structural change of the RNA-binding domain, this conserved and widely distributed isoform showed strongly impaired dsRNA-binding ability. In transfected cells, mStau(i) exhibited the same tubulovesicular distribution (RER) as mStau when weakly expressed; however, when overexpressed, mStau(i) was found in large cytoplasmic granules. Markers of the RER colocalized with mStau(i)-containing granules, showing that overexpressed mStau(i) could still be associated with the RER. Cotransfection of mStau(i) with mStau relocalized overexpressed mStau(i) to the reticular RER, suggesting that they can form a complex on the RER and that a balance between these isoforms is important to achieve proper localization. Coimmunoprecipitation demonstrated that the two mStau isoforms are components of the same complex in vivo. Analysis of the immunoprecipitates showed that mStau is a component of an RNA-protein complex and that the association with mStau(i) drastically reduces the RNA content of the complex. We propose that this new isoform, by forming a multiple-isoform complex, regulates the amount of RNA in mStau complexes in mammalian cells.

Chlamydia trachomatis mouse pneumonitis lung infection in IL-18 and IL-12 knockout mice: IL-12 is dominant over IL-18 for protective immunity

BACKGROUND

Interferon (IFN)-gamma is a key to protective immunity against a variety of intracellular bacterial infections, including Chlamydia trachomatis. Interleukin (IL)-18, a recently identified Th1 cytokine, together with IL-12 is a strong stimulator for IFN-gamma production. We investigated the relative roles of IL-18 and IL- 12 in protective immunity to C. trachomatis mouse pneumonitis (MoPn) infection using gene knockout (KO) and wild-type (WT) mice.

MATERIALS AND METHODS

Mice were intranasally infected with C. trachomatis MoPn and protective immunity was assessed among groups of mice by daily body weight changes, lung growth of MoPn, and histopathological appearances at day 10 postinfection. The corresponding immune responses for each group of mice at the same postinfection time point were evaluated by measuring antigen-specific antibody isotype responses and cytokine profiles.

RESULTS

Our results showed that IL-18 deficiency had little or no influence on clearance of MoPn from the lung, although KO mice exhibited slightly more severe inflammatory reactions in lung tissues, as well as reduced systemic and local IFN-gamma production, compared with WT mice. Results with IL-18 KO mice were in sharp contrast to those observed with IL-12 KO mice that showed substantially reduced clearance of MoPn from the lungs, substantial reductions of antigen-specific systemic and lung IFN-gamma production, decreased ratio of MoPn-specific immunoglobulin G (IgG)2a/IgG1, and severe pathological changes in the lung with extensive polymorphonuclear, instead of mononuclear, cell infiltration. Exogenous IL-12 or IL-18 was able to increase IFN-gamma production in IL-18 KO mice; whereas, only exogenous IL-12, but not IL-18, enhanced IFN-gamma production in IL-12 KO mice. Caspase-1 is the key protease for activation of IL-18 precursor into the bioactive form, and caspase-1 KO mice also displayed similar bacterial clearance and body weight loss to that in WT mice at early stages of MoPn infection. This further confirmed that IL-18 was not essential for host defense against chlamydia infection.

CONCLUSIONS

These results suggest that IL-12, rather than IL-18, plays the dominant role in the development of protective immunity against chlamydia lung infection, although both cytokines are involved in the in vivo regulation of IFN-gamma production.

In vitro and in vivo antioxidant properties of gliclazide

Diabetes is a state of increased oxidant stress and there is evidence that oxidation may play a role in the genesis of complications. Gliclazide, a sulfonylurea hypoglycemic drug, has been shown to possess free radical scavenging properties. This study examined the effects of in vitro supplementation with gliclazide and other sulfonylureas as on low-density lipoprotein (LDL) oxidation and the total plasma antioxidant capacity (TPAC). In a separate study, the effects of 10 months of oral gliclazide therapy on oxidative parameters were assessed in 44 type 2 diabetic patients. Gliclazide, but not glibenclamide, glimepiride, glipizide or tolbutamide, inhibited LDL oxidation and enhanced TPAC. With the addition of 1 microM gliclazide, oxidation lag time increased from 53.6+/-2.6 to 113.6+/-5.1 min (p<0.001), and TPAC increased from 1. 09+/-0.11 to 1.23+/-0.11 mM (p<0.01). Administration of either modified release or standard gliclazide to type 2 diabetic patients resulted in a fall in 8-isoprostanes, a marker of lipid oxidation, and an increase in the antioxidant parameters TPAC, SOD and thiols. These studies show that gliclazide possesses antioxidant properties that produce measurable clinical effects at therapeutic doses.

Genomic organization of the human and mouse stau genes

Mammalian Staufen is a double-stranded RNA-binding protein potentially involved in mRNA transport and localization. Recently, we reported that the human gene is located on chromosome 20, region q13.1. We now report the genomic organization of both the human and mouse stau genes. Amplification of genomic DNA and sequencing of the resulting PCR products indicated that the human and mouse genes are fragmented into 15 and 12 exons, distributed over at least 65 and 17 kb of genomic DNA, respectively. The three additional exons found in the human gene are subjected to differential splicing, generating four different transcripts. Corresponding exons have not been found in mouse transcripts. Apart from those three exons, the overall organization of the stau gene is similar in the two species, and the positions of the exon-intron junctions are perfectly conserved. Even an alternative choice between two splicing acceptor sites, which causes an insertion of 18 nucleotides in exon 5, is conserved in both humans and mice. An extremely G+C-rich region lacking canonical TATA and CAAT boxes was found upstream of the most 5' RACE sequence, suggesting that a housekeeping-like promoter drives the broad expression of Staufen in mammalian cells. This work represents the first step toward production of knockout mice and the elucidation of putative Staufen-linked hereditary diseases in humans.

The double-stranded RNA-binding protein Staufen is incorporated in human immunodeficiency virus type 1: evidence for a role in genomic RNA encapsidation

Human Staufen (hStau), a double-stranded RNA (dsRNA)-binding protein that is involved in mRNA transport, is incorporated in human immunodeficiency virus type 1 (HIV-1) and in other retroviruses, including HIV-2 and Moloney murine leukemia virus. Sucrose and Optiprep gradient analyses reveal cosedimentation of hStau with purified HIV-1, while subtilisin assays demonstrate that it is internalized. hStau incorporation in HIV-1 is selective, is dependent on an intact functional dsRNA-binding domain, and quantitatively correlates with levels of encapsidated HIV-1 genomic RNA. By coimmunoprecipitation and reverse transcription-PCR analyses, we demonstrate that hStau is associated with HIV-1 genomic RNA in HIV-1-expressing cells and purified virus. Overexpression of hStau enhances virion incorporation levels, and a corresponding, threefold increase in HIV-1 genomic RNA encapsidation levels. This coordinated increase in hStau and genomic RNA packaging had a significant negative effect on viral infectivity. This study is the first to describe hStau within HIV-1 particles and provides evidence that hStau binds HIV-1 genomic RNA, indicating that it may be implicated in retroviral genome selection and packaging into assembling virions.

Effect of thyroid hormone deficiency on developmental expression of goalpha gene in the brain of neonatal rats by competitive RT-PCR and in situ hybridization histochemistry

Goalpha is a guanine nucloetide-binding regulatory protein alpha subunit which is mainly distributed in the central nervous system, but it has not previously been reported how it is regulated by thyroid hormone in the brain of neonatal rat at transcriptional levels. In this report, we used quantitative competitive reverse transcriptional PCR to quantify the effects of TH deficiency on Goalpha gene expression in the brain of neonatal rat at mRNA levels. It was found that Goalpha mRNA levels in the brain of 14-day-old rats significantly increased over 3-fold after induction of perinatal hypothyroidism, and declined markedly after treatment of thyroxine replacement. In situ hybridization histochemistry was further employed to observe the time-course and spatial expression of Goalpha gene in the brain of neonatal rats affected by thyroid hormone deficiency during the developmental period. The data showed that perinatal hypothyroidism can enhance Goalpha mRNA levels in the temporal cortex, sensorimotor cortex, piriform cortex, amygdala, hippocampal CA1-4 subfields, dentate gyrus, arcuate nucleus (AR) and ventromedial hypothalamic nucleus (VMH) of hypothalamus, but not in the striate cortex, cingulate cortex, claustrum, caudate/putamen and thalamus in the brain of rat at 7-21 days post-partum. The results suggest that up-regulation of Goalpha gene expression may be one kind of common mechanism responsible for neurological deficits in some brain areas arising from thyroid hormone deficiency in the critical periods of neonatal rats.

The use of conventional antipsychotic medications for patients with schizophrenia in a medicaid population: therapeutic and cost outcomes over 2 years

OBJECTIVE

To evaluate the association between drug therapy patterns achieved with conventional antipsychotics and direct healthcare costs over 2 years.

METHODS

Paid claims data from the California Medicaid (Medi-Cal) program were used to identify 2476 patients with schizophrenia for whom 2 years of data were available. Ordinary least squares (OLS) regression models were used to estimate the association between lack of antipsychotic drug therapy, delayed therapy, changes in medications, and continuous therapy on healthcare costs over a 2-year period.

RESULTS

Nearly 99% of Medi-Cal patients with schizophrenia were treated with conventional antipsychotics. Patients with schizophrenia consumed nearly $48,000 in direct costs over 2 years. Over 16% of patients did not use any antipsychotic medication for 2 years. Untreated patients used more healthcare resources than treated patients did ($10,833, P = .0422), especially psychiatric hospital care ($8,027, P = .0004). However, treated patients frequently experienced suboptimal drug use patterns. Nearly 33% of treated patients delayed antipsychotic therapy for up to 2 years. Delayed therapy was associated with increased costs of $12,285 (P = .070). Over 56% of patients experienced changes in therapy that were associated with higher total direct costs ($17,644, P < .0001). Finally, only 3.2% of treated patients used an antipsychotic medication consistently for 2 years. However, continuous drug therapy was not associated with lower costs.

CONCLUSION

Suboptimal drug use patterns are common and costly in Medi-Cal patients with schizophrenia who initiated therapy with conventional antipsychotics.

[The prevalence of Chlamydia trachomatis and Ureaplasma urealyticum cervical infection in infertility women and the observation of therapeutic efficacy]

OBJECTIVE

To study the prevalence of Chlamydia trachomatis (CT) and Ureaplasma urealyticum (Uu) cervical infection in infertility women, and therapeutic effectiveness of tetracycline and qianglimycin.

METHOD

CT in cervical swab specimen was detected by cell culture, polymerase chain reaction(PCR) and immunofluorescent assay(IFA), Uu in cervical swab specimen was detected by culture, in a group of 145 infertility women, before and after treatment, and 45 women at productive age who attended obstetric and gynecologic clinic.

RESULT

The positive rate of CT by cell culture, PCR, IFA(shell) and IFA(direct smear) was 62.7%, 66.8%, 64.8% and 36.5%, respectively, which was obviously higher than that of the control (P < 0.01). The positive rate of Uu was 33.1%, that of CT and Uu co-infection was 18.6%. Both were obviously higher than those of the control (P < 0.01).

CONCLUSION

This study indicates that the prevalence of CT and Uu cervical infection in infertility women is high. CT and Uu cervical infection is closely related to female infertility. The therapeutic effectiveness of tetracycline and qianglimycin is not ideal.

Sialylation of the host receptor may modulate entry of demyelinating persistent Theiler's virus

Theiler's murine encephalomyelitis virus (TMEV) is a picornavirus of the Cardiovirus genus. Certain strains of TMEV may cause a chronic demyelinating disease, which is very similar to multiple sclerosis in humans, associated with a persistent viral infection in the mouse central nervous system (CNS). Other strains of TMEV only cause an acute infection without persistence in the CNS. It has been shown that sialic acid is a receptor moiety only for the persistent TMEV strains and not for the nonpersistent strains. We report the effect of sialylation on cell surface on entry and the complex structure of DA virus, a persistent TMEV, and the receptor moiety mimic, sialyllactose, refined to a resolution of 3.0 A. The ligand binds to a pocket on the viral surface, composed mainly of the amino acid residues from capsid protein VP2 puff B, in the vicinity of the VP1 loop and VP3 C terminus. The interaction of the receptor moiety with the persistent DA strain provides new understanding for the demyelinating persistent infection in the mouse CNS by TMEV.

Endothelial vasodilator function is related to low-density lipoprotein particle size and low-density lipoprotein vitamin E content in type 1 diabetes

OBJECTIVES

We sought to determine whether endothelial vasodilator function (EVF) in patients with type 1 diabetes was related to low-density lipoprotein (LDL) particle size (LDLPS), LDL vitamin E content (LDLVE) or the susceptibility of LDL to oxidation (OxLDL).

BACKGROUND

Impaired EVF is an early feature of diabetic vascular disease and may be related to oxidant stress. Although small, dense LDL and oxidized LDL are features of type 2 diabetes and predict the development of coronary artery disease, their role in type 1 diabetes is less clear.

METHODS

Endothelium-dependent vasodilation was assessed in the brachial artery (flow-mediated vasodilation [FMD]) and in the forearm resistance circulation using venous occlusion plethysmography in response to graded doses of intrabrachial acetylcholine (ACh). Thirty-seven patients with type 1 diabetes mellitus (DM) and 45 matched controls underwent flow-mediated dilation, while a subset of 19 DM and 20 controls underwent plethysmography.

RESULTS

Total, LDL and high-density lipoprotein cholesterol or triglycerides were not different in DM compared with controls, but LDLPS was smaller (25.6 +/- 0.06 vs. 26.1 +/- 0.1 nm, p < 0.05) and LDLVE was reduced (2.0 +/- 0.25 vs. 2.6 +/- 0.18 micromol/mmol LDL, p < 0.05). Oxidative susceptibility of LDL was not different. Flow-mediated vasodilation was impaired in DM compared with controls (3.6 +/- 0.6% vs. 7.1 +/- 0.5%, p < 0.005), as was the vasodilator response to ACh (p < 0.05). Flow-mediated vasodilation was directly related to LDLPS and LDLVE in both the entire study cohort and DM alone (p < 0.05), but not to other parameters of the standard lipid profile. Similarly, endothelium-dependent vasodilation in the resistance circulation was directly related to LDLPS and LDLVE, but not to OxLDL.

CONCLUSION

These results suggest, but do not prove, that LDL particle size and LDL vitamin E may be determinants of conduit and resistance vessel endothelial vasodilator function in type 1 diabetes. Further work will be required to prove cause and effect.

Mutation of predicted virion pit residues alters binding of Theiler's murine encephalomyelitis virus to BHK-21 cells

Theiler's murine encephalomyelitis virus (TMEV), a natural pathogen of mice, is a member of the genus Cardiovirus in the family Picornaviridae. Structural studies indicate that the cardiovirus pit, a deep depression on the surface of the virion, is involved in receptor attachment; however, this notion has never been systematically tested. Therefore, we used BeAn virus, a less virulent TMEV, to study the effect of site-specific mutation of selected pit amino acids on viral binding as well as other replicative functions of the virus. Four amino acids within the pit, V1091, P1153, A1225 and P3179, were selected for mutagenesis to evaluate their role in receptor attachment. Three amino acid replacements were made at each site, the first a conservative replacement, followed by progressively more radical amino acid changes in order to detect variable effects at each site. A total of seven viable mutant viruses were recovered and characterized for their binding properties to BHK-21 cells, capsid stability at 40 degrees C, viral RNA replication, single- and multistep growth kinetics, and virus translation. Our data implicate three of these residues in TMEV-cell receptor attachment.

Crystallization and preliminary X-ray diffraction studies of human epidermal growth factor

Human epidermal growth factor (hEGF), a 6.2 kDa protein of 53 amino acids with three internal disulfide bridges, has been crystallized by the hanging-drop method. hEGF crystallizes in space group P3(1)21 (or P3(2)21) using MgCl(2) as precipitant, with unit-cell parameters a = b = 61.4, c = 87.0 A. Another type of crystal, obtained using NaCl as precipitant, belongs to a tetragonal point group and has unit-cell dimensions a = b = 102.5, c = 166.6 A. The trigonal crystals with the smaller unit cell diffract X-rays better and a native data set from a single crystal has been collected to 3.0 A resolution.

Magnesium chelatase subunit D from pea: characterization of the cDNA, heterologous expression of an enzymatically active protein and immunoassay of the native protein

Mg-chelatase catalyzes the insertion of Mg into protoporphyrin and lies at the branchpoint of heme and (bacterio)chlorophyll synthesis. In prokaryotes, three genes--BchI, D and H--encode subunits for Mg-chelatase. In higher plants, homologous cDNAs for the I, D and H subunits have been characterized. Since the N-terminal half of the D subunit is homologous to the I subunit, the C-terminal portion of the pea D was used for antigen production. The antibody recognized the chloroplast D subunit and was used to demonstrate that this subunit associated with the membranes in the presence of MgCl2. The antibody immunoprecipitated the native protein and inhibited Mg-chelatase activity. Expression in Escherichia coli with a construct for the full-length protein (minus the putative transit peptide) resulted in induction of 24.5 kDa (major) and 89 kDa (minor) proteins which could only be solubilized in 6 M urea. However, when host cells were co-transformed with expression vectors for the full-length D subunit and for the 70 kDa HSP chaperonin protein, a substantial portion of the 89 kDa protein was expressed in a soluble form which was active in a Mg-chelatase reconstitution assay.

PI transfer protein: the specific recognition of phospholipids and its functions

Phosphatidylinositol transfer proteins (PITPs) can bind specifically and transfer a single phosphatidylinositol (PI) molecule between phospholipid membranes in an ATP-independent manner in vitro. PITPs exist in all the eukaryotic systems from yeast to human. PITP plays an essential role in intracellular vesicle flow and inositol lipid signaling. The crystal structure of yeast PITP Sec14p reveals a large hydrophobic pocket to accommodate the acyl chains of phospholipid molecules. At the opening of the pocket, a hydrogen bond network may render Sec14p the binding specificity to PI molecules. The structure suggests that the PI-binding ability may play an important role in the in vivo function of PITPs.

Novel aromatic inhibitors of influenza virus neuraminidase make selective interactions with conserved residues and water molecules in the active site

The active site of type A or B influenza virus neuraminidase is composed of 11 conserved residues that directly interact with the substrate, sialic acid. An aromatic benzene ring has been used to replace the pyranose of sialic acid in our design of novel neuraminidase inhibitors. A bis(hydroxymethyl)pyrrolidinone ring was constructed in place of the N-acetyl group on the sialic acid. The hydroxymethyl groups replace two active site water molecules, which resulted in the high affinity of the nanomolar inhibitors. However, these inhibitors have greater potency for type A influenza virus than for type B influenza virus. To resolve the differences, we determined the X-ray crystal structure of three benzoic acid substituted inhibitors bound to the active site of B/Lee/40 neuraminidase. The investigation of a hydrophobic aliphatic group and a hydrophilic guanidino group on the aromatic inhibitors shows changes in the interaction with the active site residue Glu275. The results provide an explanation for the difference in efficacy of these inhibitors against types A and B viruses, even though the 11 active site residues of the neuraminidase are conserved.

Hydrophobic benzoic acids as inhibitors of influenza neuraminidase

Neuraminidase (NA) plays a critical role in the life cycle of influenza virus and is a target for new therapeutic agents. A new benzoic acid inhibitor (11) containing a lipophilic side chain at C-3 and a guanidine at C-5 was synthesized. The X-ray structure of 4-(N-acetylamino)-5-guanidino-3-(3-pentyloxy)benzoic acid in complex with NA revealed that the lipophilic side chain binds in a newly created hydrophobic pocket formed by the movement of Glu 278 to interact with Arg 226, whereas the guanidine of 11 interacts in a negatively charged pocket created by Asp 152, Glu 120 and Glu 229. Compound 11 was highly selective for type A (H2N2) influenza NA (IC50 1 microM) over type B (B/Lee/40) influenza NA (IC50 500 microM).

Microtubule-dependent recruitment of Staufen-green fluorescent protein into large RNA-containing granules and subsequent dendritic transport in living hippocampal neurons

Dendritic mRNA transport and local translation at individual potentiated synapses may represent an elegant way to form synaptic memory. Recently, we characterized Staufen, a double-stranded RNA-binding protein, in rat hippocampal neurons and showed its presence in large RNA-containing granules, which colocalize with microtubules in dendrites. In this paper, we transiently transfect hippocampal neurons with human Staufen-green fluorescent protein (GFP) and find fluorescent granules in the somatodendritic domain of these cells. Human Stau-GFP granules show the same cellular distribution and size and also contain RNA, as already shown for the endogenous Stau particles. In time-lapse videomicroscopy, we show the bidirectional movement of these Staufen-GFP-labeled granules from the cell body into dendrites and vice versa. The average speed of these particles was 6.4 microm/min with a maximum velocity of 24. 3 microm/min. Moreover, we demonstrate that the observed assembly into granules and their subsequent dendritic movement is microtubule dependent. Taken together, we have characterized a novel, nonvesicular, microtubule-dependent transport pathway involving RNA-containing granules with Staufen as a core component. This is the first demonstration in living neurons of movement of an essential protein constituent of the mRNA transport machinery.

Yeast Sec14p deficient in phosphatidylinositol transfer activity is functional in vivo

Yeast phosphatidylinositol transfer protein (Sec14p) is essential for Golgi secretory function. It is widely accepted, though unproven, that phosphatidylinositol transfer between membranes represents the physiological activity of phosphatidylinositol transfer proteins (PITPs). We report that Sec14pK66,239A is inactivated for phosphatidylinositol, but not phosphatidylcholine (PC), transfer activity. As expected, Sec14pK66,239A fails to meet established criteria for a PITP in vitro and fails to stimulate phosphoinositide production in vivo. However, its expression efficiently rescues the lethality and Golgi secretory defects associated with sec14-1ts and sec14 null mutations. This complementation requires neither phospholipase D activation nor the involvement of a novel class of minor yeast PITPs. These findings indicate that PI binding/transfer is remarkably dispensable for Sec14p function in vivo.

Amino acid residues contributing to the substrate specificity of the influenza A virus neuraminidase

Influenza A viruses possess two glycoprotein spikes on the virion surface: hemagglutinin (HA), which binds to oligosaccharides containing terminal sialic acid, and neuraminidase (NA), which removes terminal sialic acid from oligosaccharides. Hence, the interplay between these receptor-binding and receptor-destroying functions assumes major importance in viral replication. In contrast to the well-characterized role of HA in host range restriction of influenza viruses, there is only limited information on the role of NA substrate specificity in viral replication among different animal species. We therefore investigated the substrate specificities of NA for linkages between N-acetyl sialic acid and galactose (NeuAcalpha2-3Gal and NeuAcalpha2-6Gal) and for different molecular species of sialic acids (N-acetyl and N-glycolyl sialic acids) in influenza A viruses isolated from human, avian, and pig hosts. Substrate specificity assays showed that all viruses had similar specificities for NeuAcalpha2-3Gal, while the activities for NeuAcalpha2-6Gal ranged from marginal, as represented by avian and early N2 human viruses, to high (although only one-third the activity for NeuAcalpha2-3Gal), as represented by swine and more recent N2 human viruses. Using site-specific mutagenesis, we identified in the earliest human virus with a detectable increase in NeuAcalpha2-6Gal specificity a change at position 275 (from isoleucine to valine) that enhanced the specificity for this substrate. Valine at position 275 was maintained in all later human viruses as well as swine viruses. A similar examination of N-glycolylneuraminic acid (NeuGc) specificity showed that avian viruses and most human viruses had low to moderate activity for this substrate, with the exception of most human viruses isolated between 1967 and 1969, whose NeuGc specificity was as high as that of swine viruses. The amino acid at position 431 was found to determine the level of NeuGc specificity of NA: lysine conferred high NeuGc specificity, while proline, glutamine, and glutamic acid were associated with lower NeuGc specificity. Both residues 275 and 431 lie close to the enzymatic active site but are not directly involved in the reaction mechanism. This finding suggests that the adaptation of NA to different substrates occurs by a mechanism of amino acid substitutions that subtly alter the conformation of NA in and around the active site to facilitate the binding of different species of sialic acid.

A GABAergic, strongly inhibitory projection to a thalamic nucleus in the zebra finch song system

The anterior forebrain pathway (AFP) of the oscine song system is essential for song learning but not song production. Most cells recorded in this serially connected pathway show increased firing in response to song playback, suggesting largely excitatory connections among AFP nuclei. However, the neurons forming a key projection in this pathway, from area X to the medial nucleus of the dorsolateral thalamus (DLM), express glutamic acid decarboxylase in their somata and terminals, suggesting an inhibitory connection. To investigate the firing properties of DLM neurons and the functional influence of area X afferents in DLM, we made whole-cell recordings from DLM neurons in brain slices from adult male zebra finches. Most cells had intrinsic properties closely resembling those of mammalian thalamocortical cells, including a low-threshold Ca(2+) spike and time-dependent, hyperpolarization-activated inward rectification. Activation of afferents from area X evoked a strong, all-or-none IPSP whose amplitude and latency were unchanged by application of glutamate antagonists, consistent with a monosynaptic contact. The IPSP had a reversal potential near -70 mV and was blocked by the GABA(A) receptor antagonist bicuculline methiodide. Post-inhibitory rebound firing occurred in DLM neurons with a delay near 50 msec. Strong inhibition can combine with the intrinsic properties of DLM neurons to allow signaling on disinhibition. Our data are consistent with the hypothesis that the AFP corresponds to the mammalian corticobasal ganglia-thalamocortical loop. The similar functional properties of avian and mammalian thalamic neurons suggest conserved forebrain mechanisms of sensorimotor information processing across vertebrate taxa.

Design of benzoic acid inhibitors of influenza neuraminidase containing a cyclic substitution for the N-acetyl grouping

A 2-pyrrolidinone ring containing a single hydroxymethyl side chain effectively replaces the N-acetylamino group of 4-(N-acetylamino)-3-guanidinobenzoic acid, a low micromolar inhibitor of influenza neuraminidase. This novel structural template affords new opportunities to evolve more potent benzoic acid inhibitors.

Potent inhibition of influenza sialidase by a benzoic acid containing a 2-pyrrolidinone substituent

On the basis of the lead compound 4-(N-acetylamino)-3-guanidinobenzoic acid (BANA 113), which inhibits influenza A sialidase with a Ki of 2.5 microM, several novel aromatic inhibitors of influenza sialidases were designed. In this study the N-acetyl group of BANA 113 was replaced with a 2-pyrrolidinone ring, which was designed in part to offer opportunities for introduction of spatially directed side chains that could potentially interact with the 4-, 5-, and/or 6-subsites of sialidase. While the parent structure 1-(4-carboxy-2-guanidinophenyl)pyrrolidin-2-one (8) was only a modest inhibitor of sialidase, the introduction of a hydroxymethyl or bis(hydroxymethyl) substituent at the C5' position of the 2-pyrrolidinone ring resulted in inhibitors (9 and 12, respectively) with low micromolar activity. Crystal structures of these inhibitors in complex with sialidase demonstrated that the substituents at the 5'-position of the 2-pyrrolidinone ring interact in the 4- and/or 5-subsites of the enzyme. Replacement of the guanidine in 12 with a hydrophobic 3-pentylamino group resulted in a large enhancement in binding to produce an inhibitor (14) with an IC50 of about 50 nM against influenza A sialidase, although the inhibition of influenza B sialidase was 2000-fold less. This represents the first reported example of a simple, achiral benzoic acid with potent (low nanomolar) activity as an inhibitor of influenza sialidase.

High-resolution sequence typing of HLA-DQA1 and -DQB1 exon 2 DNA with taxonomy-based sequence analysis (TBSA) allele assignment

High-resolution DNA sequencing of exon 2 of DQA1 and DQB1 genes that uses a taxonomy-based sequence analysis (TBSA) method to assign alleles was developed. The system uses fewer primers for polymerase chain reaction (PCR) amplification and sequencing than other methods and yields accurate DQA1 and DQB1 typing when either homozygous or heterozygous DNA samples are tested. The approach was initially corroborated by the correct typing of 10 blinded samples that had been previously typed by PCR using sequence-specific oligonucleotide probes (PCR-SSOP) or serology, and subsequently confirmed by sequencing of cloned PCR products. DNA from peripheral blood cell samples of 130 individuals enrolled in a case-control analysis of HLA determinants of abdominal aortic aneurysm were subsequently evaluated. Overall, 8 different DQA1 and 19 DQB1 alleles were identified. All 21 DQA1 heterozygous combinations and 45 of 49 DQB1 heterozygous combinations were successfully resolved with TBSA. The two pairs of heterozygous DQB1 combinations that were not unambiguously typed required sequence specific PCR amplification for correct allele identification. We conclude that the method provides precise analysis for HLA-DQ typing.

Characterization and localization to chromosome 7 of psihGABPalpha, a human processed pseudogene related to the ets transcription factor, hGABPalpha

GABP is a heteromeric transcription factor complex which consists of the ets related protein, GABPalpha, and the Notch-related protein, GABPbeta. We isolated a human genomic DNA fragment which is highly homologous and colinear with human GABPalpha cDNA, but which lacks introns. This processed pseudogene, psihGABPalpha, is expressed as RNA in U937 human myeloid cells, but a mutation at the site that corresponds to the ATG start methionine codon prevents its translation into protein. The pseudogene was localized to chromosome 7 using a somatic cell hybrid mapping panel and it is not syntenic with authentic GABPalpha, which was localized to chromosome 21. We have identified psihGABPalpha, a novel, GABPalpha-related processed pseudogene which is expressed as a RNA transcript in human myeloid cells.