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Biomedical subjects

E Arnold

Publications and source records attributed to E Arnold.

At least 55 records · Page 3Linked to original sources
PubMed1998

Improving general practitioner clinical records with a quality assurance minimal intervention.

BACKGROUND: Although good medical records have been associated with good care, there is considerable room for their improvement in general practice. AIM: To improve the quality of general practice medical records at minimal cost. METHOD: A total of 150 randomly sampled general practitioners (GPs) in suburban Brisbane, Australia, were randomized in a controlled trial to receive or not receive an intervention. The intervention consisted of 6 to 12 one-hour monthly meetings when the pairs of GPs assessed samples of each other's medical records using a 12-item instrument. This was developed previously by a process of consensus of general practice teachers. Mean scores of 10 medical records selected at random from before the intervention started and one year later were compared. RESULTS: After the intervention, the increase in the total score (for which the maximum possible was 18) for the intervention GPs (from a baseline of 11.5 to 12.3) was not significantly greater than for the controls (from 11.4 to 11.7). Legibility and being able to determine the doctor's assessment of the consultation were significantly improved. The post-intervention increase of 1.06 (9.3%) of the total scores of the 47% of intervention GPs who complied with the intervention was significantly greater than that for the controls. CONCLUSION: The quality assurance activity improved some components of the quality of GPs' clinical records. However, the improvement was small, and the search for activities for Australian GPs that demonstrate an improvement in the quality of their practice must continue.

Family Practice↗
PubMed1997

CASH, a novel caspase homologue with death effector domains.

CASP-8 and CASP-10, members of a cysteine protease family that participates in apoptosis, interact with MORT1/FADD, an adapter protein in the CD120a (p55 tumor necrosis factor receptor), and CD95 (Fas/Apo-1) death-inducing signaling pathways, through a shared N-terminal sequence motif, the death effector domain. We report cloning of two splice variants of a novel protein, CASH, that contain two N-terminal death effector domains and can bind through them to each other, to MORT1/FADD, to CASP-8, and to CASP-10. The unique C-terminal part of the longer variant shows marked sequence homology to the caspase protease region yet lacks several of the conserved caspase active site residues, suggesting that it is devoid of cysteine protease activity. Overexpression of the short CASH splice variant strongly inhibited cytotoxicity induction by CD120a and CD95. Expression of the longer variant, while inhibiting cytotoxicity in HeLa cells, had a marked cytocidal effect in 293 cells that could be shown to involve its protease homology region. The findings suggest that CASH acts as an attenuator and/or initiator in CD95 and CD120a signaling for cell death.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Structure of poliovirus type 2 Lansing complexed with antiviral agent SCH48973: comparison of the structural and biological properties of three poliovirus serotypes.

BACKGROUND: Polioviruses are human pathogens and the causative agents of poliomyelitis. Polioviruses are icosahedral single-stranded RNA viruses, which belong to the picornavirus family, and occur as three distinct serotypes. All three serotypes of poliovirus can infect primates, but only type 2 can infect mice. The crystal structures of a type 1 and a type 3 poliovirus are already known. Structural studies of poliovirus type 2 Lansing (PV2L) were initiated to try to enhance our understanding of the differences in host range specificity, antigenicity and receptor binding among the three serotypes of poliovirus. RESULTS: The crystal structure of the mouse neurovirulent PV2L complexed with a potent antiviral agent, SCH48973, was determined at 2.9 A resolution. Structural differences among the three poliovirus serotypes occur primarily in the loop regions of the viral coat proteins (VPs), most notably in the loops of VP1 that cluster near the fivefold axes of the capsid, where the BC loop of PV2L is disordered. Unlike other known structures of enteroviruses, the entire polypeptide chain of PV2L VP4 is visible in the electron density and RNA bases are observed stacking with conserved aromatic residues (Tyr4020 and Phe4046) of VP4. The broad-spectrum antiviral agent SCH48973 is observed binding in a pocket within the beta-barrel of VP1, in approximately the same location that natural 'pocket factors' bind to polioviruses. SCH48973 forms predominantly hydrophobic interactions with the pocket residues. CONCLUSIONS: Some of the conformational changes required for infectivity and involved in the control of capsid stability and neurovirulence in mice may occur in the vicinity of the fivefold axis of the poliovirus, where there are significant structural differences among the three poliovirus serotypes in the surface exposed loops of VP1 (BC, DE, and HI). A surface depression is located at the fivefold axis of PV2L that is not present in the other two poliovirus serotypes. The observed interaction of RNA with VP4 supports the observation that loss of VP4 ultimately leads to the loss of viral RNA. A model is proposed that suggests dual involvement of the virion fivefold and pseudo-threefold axes in receptor-mediated initiation of infection by picornaviruses.

Adaptation, Physiological↗
PubMed1997

A transcript map encompassing the multiple endocrine neoplasia type-1 (MEN1) locus on chromosome 11q13.

A transcription map of a 1200-kb region encompassing the MEN1 locus was constructed by direct cDNA selection and mapping ESTs. A total of 29 genes were mapped. Ten transcripts were identified by cDNA selection of a focused 300-kb genomic region telomeric to the MEN1 consensus region. Since many of the sequences cloned by cDNA selection also identified ESTs from the region, 19 additional RH-mapped ESTs were mapped to the entire contig region by PCR amplification of genomic clones. Nine known genes, 2 putative human homologues to mouse genes, and 18 novel transcripts map to the region. Transcripts that map to the MEN1 interval PYGM-D11S449 include SGC35223, IB1256, AA147620, ZFM1, FAU, and CAPN1. The latter 3 known genes have already been excluded as candidate MEN1 genes. The 2 putative human homologues of mouse genes Ltbp2 and Spa-1 may be candidate tumor suppressor genes, but they map telomeric to D11S449. Although both of these genes map outside the MEN1 consensus region they may play a role in sporadic endocrine tumors independent of the MEN1 gene or in other tumors, such as breast cancer, that have loss of heterozygosity within this region.

Blotting, Northern↗
PubMed1997

Protein-nucleic acid interactions and DNA conformation in a complex of human immunodeficiency virus type 1 reverse transcriptase with a double-stranded DNA template-primer.

The conformation of the DNA and the interactions of the nucleic acid with the protein in a complex of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) and 19-mer/18-mer double-stranded DNA template-primer (dsDNA) are described. The structure of this HIV-1 RT complex with dsDNA serves as a useful paradigm for studying aspects of nucleotide polymerases such as catalysis, fidelity, drug inhibition, and drug resistance. The bound dsDNA has a bend of approximately 41 degrees at the junction of an A-form region (first five base pairs near the polymerase active site) and a B-form region (the last nine base pairs toward the RNase H active site). The 41 degrees bend occurs smoothly over the four base pairs between the A-form portion and the B-form portion in the vicinity of helices alpha H and alpha I of the p66 thumb subdomain. The interactions between the dsDNA and protein primarily involve the sugar-phosphate backbone of the nucleic acid and structural elements of the palm, thumb, and RNase H of p66, and are not sequence specific. Amino acid residues from the polymerase active site region, including amino acid residues of the conserved Tyr-Met-Asp-Asp (YMDD) motif and the "primer grip," interact with 3'-terminal nucleotides of the primer strand and are involved in positioning the primer terminal nucleotide and its 3'-OH group at the polymerase active site. Amino acid residues of the "template grip" have close contacts with the template strand and aid in positioning the template strand near the polymerase active site. Helix alpha H of the p66 thumb is partly inserted into the minor groove of the dsDNA and helix alpha I is directly adjacent to the backbone of the template strand. Amino acid residues of beta 1', alpha A', alpha B', and the loop containing His539 of the RNase H domain interact with the primer strand of the dsDNA.

DNA↗
PubMed1997

Protein engineering to create biologically active peptides: recombinant human rhinoviruses that display peptide sequences.

This paper describes the use of human rhinovirus to display peptides corresponding to biologically active sequences. While this system can be used to reconstruct essentially any biologically active sequence for which there is a corresponding ligand that can be used for its selection, we have focused on using this system to display immunogens from dangerous pathogens as a means to develop vaccines. Five mutagenesis approaches are illustrated as ways to generate functionally active moieties. The mutagenesis approaches illustrated can be employed with any of a large number of possible display vectors; however, human rhinovirus might be especially useful in cases where it will be important to derive the benefits of delivery by a live-virus approach. Examples are shown in which reconstruction of immunogens corresponding to the V3 loop of the gp120 glycoprotein of the human immunodeficiency virus type 1 (HIV-1) on the surface of rhinovirus has yielded apparently effective mimics of the HIV-1 immunogens (as measured by their ability to be neutralized by anti-HIV-1 antibodies as well as their ability to elicit the production of antibodies capable of neutralizing HIV-1 in cell culture). This system offers the opportunity to reconstruct functionally important moieties that derive from proteins or pathogens that are either too dangerous or difficult to isolate for use as vaccine preparations themselves.

Amino Acid Sequence↗
PubMed1997

The stress connection. Women and coronary heart disease.

Assessment and treatment of the stressors associated with major medical illness such as CHD without regard to gender overlooks women's issues in some extremely fundamental ways. To ensure that rehabilitation formats are relevant for women, more qualitative studies are needed so that women can give voice to the story of an MI recovery from a feminine perspective. It is vital to understand the psychologic contribution to the development and treatment of CHD both as described by women in their own words and as evaluated by distinctly feminine constructs. Assessment of psychosocial factors should be an essential component of a CHD diagnostic evaluation. Although little can be done about a genetic predisposition to CHD, education and personal support can help women make needed lifestyle changes to forestall further cardiac damage and to improve a woman's level of functioning. The capacity to take charge of one's life and social support are strong counterpoints to negative psychosocial symptoms of CHD. There is a strong need to make rehabilitation programs for women with CHD contextually congruent. Strategies to involve women in cardiac rehabilitation must take into account a woman's needs, providing both age-appropriate physical exercise and psychologic social support for women at times convenient to their schedules. Women must be given permission to let go of normally performed duties after a major cardiac event and to seek out what is meaningful. Group formats that offer women essential social support, an opportunity to verbally process the meaning of a life-threatening diagnosis, an opportunity to share their experiences with other women, and the ability to reconstruct a new sense of self based on feminine constructs may be as important for women as other lifestyle structural components in effective rehabilitation programs. Society must reclassify the CHD disease process as one that equally affects women. Research studies with women as primary subjects and key informants can provide needed direction in the identification of psychosocial risk factors and appropriate treatments to reduce alarming morbidity and mortality of CHD in women. More data are needed about the psychosocial mechanisms that aggravate and mediate physiologic responses in CHD in women.

Coronary Disease↗
PubMed1996

Crystal structures of 8-Cl and 9-Cl TIBO complexed with wild-type HIV-1 RT and 8-Cl TIBO complexed with the Tyr181Cys HIV-1 RT drug-resistant mutant.

Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) is an important target for chemotherapeutic agents used in the treatment of AIDS; the TIBO compounds are potent non-nucleoside inhibitors of HIV-1 RT (NNRTIs). Crystal structures of HIV-1 RT complexed with 8-Cl TIBO (R86183, IC50 = 4.6 nM) and 9-Cl TIBO (R82913, IC50 = 33 nM) have been determined at 3.0 A resolution. Mutant HIV-1 RT, containing Cys in place of Tyr at position 181 (Tyrl81Cys), is highly resistant to many NNRTIs and HIV-1 variants containing this mutation have been selected in both cell culture and clinical trials. We also report the crystal structure of Tyrl81Cys HIV-1 RT in complex with 8-Cl TIBO (IC50 = 130 nM) determined at 3.2 A resolution. Averaging of the electron density maps computed for different HIV-1 RT/NNRTI complexes and from diffraction datasets obtained using a synchrotron source from frozen (-165 degrees C) and cooled (-10 degrees C) crystals of the same complex was employed to improve the quality of electron density maps and to reduce model bias. The overall locations and conformations of the bound inhibitors in the complexes containing wild-type HIV-1 RT and the two TIBO inhibitors are very similar, as are the overall shapes and volumes of the non-nucleoside inhibitor-binding pocket (NNIBP). The major differences between the two wild-type HIV-1 RT/TIBO complexes occur in the vicinity of the TIBO chlorine substituents and involve the polypeptide segments around the beta5-beta6 connecting loop (residues 95 to 105) and the beta13-beta14 hairpin (residues 235 and 236). In all known structures of HIV-1 RT/NNRTI complexes, including these two, the position of the beta12-beta13 hairpin or the "primer grip" is significantly displaced relative to the position in the structure of HIV-1 RT complexed with a double-stranded DNA and in unliganded HIV-1 RT structures. Since the primer grip helps to position the template-primer, this displacement suggests that binding of NNRTIs would affect the relative positions of the primer terminus and the polymerase active site. This could explain biochemical data showing that NNRTI binding to HIV-1 RT reduces efficiency of the chemical step of DNA polymerization, but does not prevent binding of either dNTPs or DNA. When the structure of the Tyr181Cys mutant HIV-1 RT in complex with 8-Cl TIBO is compared with the corresponding structure containing wild-type HIV-1 RT, the overall conformations of Tyr181Cys and wild-type HIV-1 RT and of the 8-Cl TIBO inhibitors are very similar. Some positional changes in the polypeptide backbone of the beta6-beta10-beta9 sheet containing residue 181 are observed when the Tyr181Cys and wild-type complexes are compared, particularlty near residue Val179 of beta9. In the p51 subunit, the Cys181 side-chain is oriented in a similar direction to the Tyr181 side-chain in the wild-type complex. However, the electron density corresponding to the sulfur of the Cys181 side-chain in the p66 subunit is very weak, indicating that the thiol group is disordered, presumably because there is no significant interaction with either 8-Cl TIBO or nearby amino acid residues. In the mutant complex, there are slight rearrangements of the side-chains of other amino acid residues in the NNIBP and of the flexible dimethylallyl group of 8-Cl TIBO; these conformational changes could potentially compensate for the interactions that were lost when the relatively large tyrosine at position 181 was replaced by a less bulky cysteine residue. In the corresponding wild-type complex, Tyr181 iin the p66 subunit has significant interactions with the bound inhibitor and the position of the Tyr181 side-chain is well defined in both subunits. Apparently the Tyr181 --> Cys mutation eliminates favorable contacts of the aromatic ring of the tyrosine and the bou

Antiviral Agents↗
PubMed1996

Structure of unliganded HIV-1 reverse transcriptase at 2.7 A resolution: implications of conformational changes for polymerization and inhibition mechanisms.

BACKGROUND: HIV-1 reverse transcriptase (RT) is a major target for anti-HIV drugs. A considerable amount of information about the structure of RT is available, both unliganded and in complex with template-primer or non-nucleoside RT inhibitors (NNRTIs). But significant conformational differences in the p66 polymerase domain among the unliganded structures have complicated the interpretation of these data, leading to different proposals for the mechanisms of polymerization and inhibition. RESULTS: We report the structure of an unliganded RT at 2.7 A resolution, crystallized in space group C2 with a crystal packing similar to that of the RT-NNRTI complexes. The p66 thumb subdomain is folded into the DNA-binding cleft. Comparison of the unliganded RT structures with the DNA-bound RT and the NNRTI-bound RT structures reveals that the p66 thumb subdomain can exhibit two different upright conformations. In the DNA-bound RT, the p66 thumb subdomain adopts an upright position that can be described as resulting from a rigid-body rotation of the p66 thumb along the "thumb's knuckle' located near residues Trp239 (in strand beta 14) and Val317 (in beta 15) compared with the thumb position in the unliganded RT structure. NNRTI binding induces an additional hinge movement of the p66 thumb near the thumb's knuckle, causing the p66 thumb to adopt a configuration that is even more extended than in the DNA-bound RT structure. CONCLUSIONS: The p66 thumb subdomain is extremely flexible. NNRTI binding induces both short-range and long-range structural distortions in several domains of RT, which are expected to alter the position and conformation of the template-primer. These changes may account for the inhibition of polymerization and the alteration of the cleavage specificity of RNase H by NNRTI binding.

Anti-HIV Agents↗
PubMed1996

Synthesis and activity of piperazine-containing antirhinoviral agents and crystal structure of SDZ 880-061 bound to human rhinovirus 14.

A series of antipicornaviral agents containing piperazinyl moieties was synthesized with the objective of obtaining a compound with a broad spectrum of antirhinovirus activity, high potency (< or = 0.003 microgram/ml), and low cytotoxicity (> or = 30 micrograms/ml). Five compounds of this series were evaluated in detail for efficacy against various HRV serotypes. The agent SDZ 880-061, containing the benzothiazine moiety SDZ 108-075, which is particularly active against HRV14, and the thiazolyl acetic acid ester group of SDZ 89-124, which is potent against HRV1B, indeed has a relatively broad antiviral spectrum. SDZ 880-061 inhibited 85% of 89 HRV serotypes tested at a concentration of < or = 3 micrograms/ml. The 3.0 A resolution X-ray structure of SDZ 880-061 bound to HRV14 has revealed the binding characteristics of this potent compound. It binds in the same pocket as other capsid-binding antiviral agents characterized to date, leaving the innermost portion of the pocket vacant. The binding causes similar, although less extensive, alterations of the HRV14 VP1 backbone conformation (residues 100 to 110, 151 to 159, and 213 to 224) compared to other antiviral agents analyzed structurally. Although the contacts between SDZ 880-061 and HRV14 are mostly of hydrophobic character, the inhibitor has three relatively short polar interactions with residues of VP1 that represent potential hydrogen bonds. The amount of solvent-accessible surface area of SDZ 880-061 buried in the complex (613 A2) is within the range of that observed in protein-protein interfaces. The observed influence of time of addition or removal of SDZ 880-061 on virus yield and on the infectious-center formation indicates that the compound primarily interferes with HRV14 cellular attachment. Since it is assumed that uncoating requires virion instability and/or flexibility, the finding that SDZ 880-061 has only a marginal effect on uncoating may be due to the fact that it does not completely fill the hydrophobic pocket.

Antiviral Agents↗
PubMed1996

Use of chimeric human immunodeficiency virus types 1 and 2 reverse transcriptases for structure-function analysis and for mapping susceptibility to nonnucleoside inhibitors.

The human immunodeficiency virus type 1 and type 2 (HIV-1 and HIV-2) reverse transcriptases (RTs) are evolutionary related. To study the effect of homologous sequence replacements on polymerase function and to map the determinants of the lack of susceptibility of HIV-2 RT to nonnucleoside drugs, a series of chimeric HIV-1/HIV-2 RTs were constructed. Analysis of the chimeric RTs showed that wild-type levels of RNA-dependent DNA polymerase activity were retained when both finger and palm subdomains were exchanged as a unit between the two parental RTs. Analysis of enzymatically active chimeras for inhibition by the thiobenzimidazolone derivative TIBO R82150 showed that a segment of HIV-2 RT at 212-250, when placed in the HIV-1 RT context, conferred a 40-fold decrease in susceptibility to TIBO R82150. Site-directed mutagenesis of this segment found Tyr227 to be a key residue in this segment for the natural resistance of HIV-2 RT to TIBO R82150.

Amino Acids↗
PubMed1996

Selective pressure of a quinoxaline nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) on HIV-1 replication results in the emergence of nucleoside RT-inhibitor-specific (RT Leu-74-->Val or Ile and Val-75-->Leu or Ile) HIV-1 mutants.

The quinoxaline nonnucleoside RT inhibitor (NNRTI) (S)-4-isopropoxycarbonyl-6-methoxy-3-(methylthiomethyl)-3,4- dihydroquinoxaline-2(1H)-thione (HBY 097) was used to select for drug-resistant HIV-1 variants in vitro. The viruses first developed mutations affecting the NNRTI-binding pocket, and five of six strains displayed the RT G190-->E substitution, which is characteristic for HIV-1 resistance against quinoxalines. In one variant, a new mutant (G190-->Q) most likely evolved from preexisting G190-->E mutants. The negative charge introduced by the G190-->E substitution was maintained at that site of the pocket by simultaneous selection for V179-->D together with G190-->Q. After continued exposure to the drug, mutations at positions so far known to be specific for resistance against nucleoside RT inhibitors (NRTIs) (L74-->V/I and V75-->L/I) were consistently detected in all cultures. The inhibitory activities of the cellular conversion product of 2',3'-dideoxyinosine (ddI, didanosine), 2',3'-dideoxyadenosine (ddA) and of 2',3'-didehydro-3'-deoxythymidine (d4T, stavudine) against these late-passage viruses were shown to be enhanced with the L74-->V/I RT mutant virus as compared with the wild-type (wt) HIV-1MN isolate. Clonal analysis proved linkage of the codon 74 and codon 75 mutations to the NNRTI-specific mutations in all RT gene fragments. The nonnucleoside- and nucleoside-resistance mutation sites are separated by approximately 35 A. We propose that the two sites "communicate" through the template-primer which is situated in the DNA-binding cleft between these two sites. Quinoxalines cause high selective pressure on HIV-1 replication in vitro; however, the implication of these findings for the treatment of HIV-1 infection has yet to be determined.

Antiviral Agents↗
PubMed1996

An in vivo mutation from leucine to tryptophan at position 210 in human immunodeficiency virus type 1 reverse transcriptase contributes to high-level resistance to 3'-azido-3'-deoxythymidine.

Sequencing of the reverse transcriptase (RT) region of 26 human immunodeficiency virus type 1 (HIV-1) isolates from eight patients treated with 3'-azido-3'-deoxythymidine (AZT) revealed a mutation at codon 210 from TTG (leucine) to TGG (tryptophan) exclusively in association with resistance to AZT. The mutation Trp-210 was observed in 15 of the 20 isolates phenotypically resistant to AZT, being more commonly observed than resistance-associated mutations at codons 67, 70, and 219. Trp-210 was never observed before the emergence of resistance-associated mutations Leu-41 and Tyr-215, and in a sequential series of five isolates from one patient the order of emergence of mutations was found to be Tyr-215, Leu-41, and then Trp-210. Trp-210 was also found in association with the Leu-41, Asn-67, Arg-70, and Tyr-215 resistance genotype. To define the role of Trp-210 in AZT resistance, molecular HIV-1 clones were constructed with various combinations of RT mutations at codons 41, 67, 70, 210, and 215 and tested for susceptibility to AZT. In clones with polymerase genes derived either from HXB2-D or clinical isolates, Trp-210 alone did not increase AZT resistance, whereas in conjunction with Leu-41 and Tyr-215, Trp-210 contributed to high-level resistance (50% inhibitory concentration of >1 microM). In HXB2-D, Trp-210 with Tyr-215 generated a virus with resistance comparable to one with Leu-41, Tyr-215, and Trp-210. Inserting Trp-210 into the genetic context of mutations at codons 41, 67, 70, and 215 further enhanced resistance from a 50% inhibitory concentration of 1.44 microM to 8.41 microM. Molecular modeling of the tertiary structure of HIV-1 RT revealed that the distance between the side chains of Trp-210 (in helix alphaF) and Tyr-215 (in strand beta11a) approximated 4 A (1 A = 0.1 nm), sufficiently close to result in significant energetic interaction between these two aromatic side chains. In conclusion, Trp-210 contributes significantly to phenotypic AZT resistance of HIV-1 by augmenting resistance at least three- to sixfold in the context of two resistant genotypes, and its effect may require an interaction with an aromatic amino acid at position 215.

Base Sequence↗
PubMed1996

Inhibition of human immunodeficiency virus type 1 integrase by the Fab fragment of a specific monoclonal antibody suggests that different multimerization states are required for different enzymatic functions.

We have characterized a murine monoclonal antibody (MAb 35), which was raised against human immunodeficiency virus type 1 (HIV-1) integration protein (IN), and the corresponding Fab 35. Although MAb 35 does not inhibit HIV-1 IN, Fab 35 does. MAb 35 (and Fab 35) binds to an epitope in the C-terminal region of HIV-1 IN. Fab 35 inhibits 3'-end processing, strand transfer, and disintegration; however, DNA binding is not affected. The available data suggest that Fab 35 inhibits enzymatic activities of IN by interfering with the ability of IN to form multimers that are enzymatically active. This implies that the C-terminal region of HIV-1 IN participates in interactions that are essential for the multimerization of IN. Titration of the various IN-mediated enzymatic activities suggests that different degrees of multimerization are required for different activities of HIV-1 IN.

Antibodies, Monoclonal↗
PubMed1996

Chimeric rhinoviruses as tools for vaccine development and characterization of protein epitopes.

Chimeric human rhinoviruses (HRVs) have the potential to serve as vaccines against a wide variety of diseases. Such vaccines can be developed optimally by generating libraries of chimeric HRVs displaying immunogens from dangerous pathogens or tumor cells in many different conformations. Extremely large numbers of conformationally defined presentations of foreign epitopes can be produced efficiently by flanking transplanted epitopes with linkers, or adapters, of small segments of randomized amino acids. In addition, the individual residues of the immunogenic sequences can be encoded in proportion to their prevalence in databases, generating composite immunogens that function as mimotopes. The diversity of sequences and conformations improves the likelihood of generating immunologically valuable vaccine candidates. Chimeric viruses thus generated can be propagated and purified to select for viruses whose growth and physical stability are like those of wild-type HRV. Viruses containing a foreign epitope in antigenically relevant conformations can then be captured by immunoselection with neutralizing antibodies directed against the foreign pathogen. Using this approach, we have been able to generate HRV chimeras that present V3 loop sequences of the human immunodeficiency virus type 1 (HIV-1) in immunologically relevant conformations. Antisera directed against such chimeras can neutralize multiple strains of HIV-1 in cell culture, suggesting that the HRV14:HIV-1 chimeras may be presenting their V3 loop sequences in manners that mimic those of multiple strains of HIV. Immunologically interesting chimeras can be examined using X-ray crystallography to yield detailed information about the structures of chimeras with immunogenic epitopes. This information may lead to a greater understanding of key functional and structural elements of immunogenicity. The chimeric HRV system allows one to present virtually any protein epitope or mimitope thereof, identify viruses with immunological characteristics that mimic those of the foreign pathogen, and examine the structures of these immunogenic sequences at the atomic level.

Epitopes↗
PubMed1996

Targeting HIV reverse transcriptase for anti-AIDS drug design: structural and biological considerations for chemotherapeutic strategies.

The reverse transcriptase of HIV is a key target for the antiviral treatment of AIDS. Numerous potent inhibitors of RT have been described including all of the drugs that have been currently licensed for the treatment of AIDS, but their efficacy has been limited by the emergence of drug-resistant HIV variants. Extensive biochemical, genetic, and clinical data about HIV RT enzymatic mechanisms, inhibition, and drug resistance have been reported. This information, taken together with structural data from crystallographic studies of HIV-1 RT, has set the stage for structure-based design of improved inhibitors of this essential viral enzyme. Comparisons of the different crystal structures of HIV-1 RT shows that the enzyme has great conformational flexibility, providing additional possibilities for drug targeting. Recent clinical and virological data suggest that HIV-1 RT enzymes that carry drug-resistance mutations can be substantially impaired and that combinations of RT inhibitors can produce significant clinical benefit in the treatment of AIDS. An immediate goal is to use the available information to design specific inhibitors or combination therapies that will select for relatively less fit HIV variants.

Binding Sites↗
PubMed1996

What is the quality of general practitioner records in Australia?

OBJECTIVE: To describe the quality of general practitioner (GP) medical records. SUBJECTS AND SETTING: One hundred and fifty fee-for-service GPs in suburban Brisbane. SETTING OF STANDARDS: Standards were set at meetings with general practitioner educators, and refined after circulating drafts to participants. Criteria were established in the 12 areas of: general ease-of-use (legibility; consciousness; and layout); whether certain patient data could be found (date of birth; past medical history; family history; allergies; alcohol and tobacco use; and immunisation status); and whether information about the most recent consultation could be found, (the reason for the consultation; its assessment; and management). MAIN OUTCOME MEASURES: Ten randomly selected medical records of consultations from each of the GPs scored blind by medical students. RESULTS: The mean weighted score was 11.4 out of a maximum possible of 18. Most records attained the standard with: consciousness (97%); recording date of birth (94%); and immunisation status (92%). Fewest attained the standard with family history (12%); adequate layout (17%); and recording alcohol and tobacco use (31%). Practice size and membership of the Royal Australian College of General Practitioners were not associated with significant differences in score, although sex, (being female) and date of graduation, (recent), were associated with significantly higher scores. CONCLUSION: There is considerable room for improvement in the quality of the clinical records of Australian GPs.

Analysis of Variance↗