Using the Zeno line to assess and refine molecular models

The Zeno line is the locus of points on the temperature-density plane where the compressibility factor of the fluid is equal to one. It has been observed to be straight for a broad variety of real fluids, although the underlying reasons for this are still unclear. In this work, a detailed study of the Zeno line and its relation to the vapor-liquid coexistence curve is performed for two simple model pair-potential fluids: attractive square-well fluids with varying well-widths λ and Mie n-6 fluids with different repulsive exponents n. Interestingly, the Zeno lines of these fluids are curved, regardless of the value of λ or n. We find that for square-well fluids, λ ≈ 1.8 presents a Zeno line, which is the most linear over the largest temperature range. For Mie n-6 fluids, we find that the straightest Zeno line occurs for n between 8 and 10. Additionally, the square-well and Mie fluids with the straightest Zeno line showed the closest quantitative agreement with the vapor-liquid coexistence curve for experimental fluids that follow the principle of corresponding states (e.g., argon, xenon, krypton, methane, nitrogen, and oxygen). These results suggest that the Zeno line can provide a useful additional feature, in complement to other properties, such as the phase envelope, to evaluate molecular models.

Model-Based Optimization of Laser Excitation and Detection Improves Spectral Contrast in Noninvasive Diffuse Raman Spectroscopy

Spatially offset Raman spectroscopy (SORS) is a powerful technique for subsurface molecular analysis of optically turbid samples. Numerical modeling of light propagation has been used to investigate opportunities for improving spectral contrast and signal to noise ratio when imaging regions of interest located 0-4.5 mm below the surface in polymer bulk material. Two- and three-dimensional modeling results demonstrate that when analyzing a certain region of interest (ROI) of finite lateral dimensions below the sample surface, offsetting both the laser source and detector in opposite directions from the central point of the ROI can increase the spectral contrast as compared to conventional SORS approach where the detector or the laser source is maintained at the central point (centered SORS). The outlined modeling results have been validated experimentally using a bulk polymer sample with a trans-stilbene ROI (cylinder) below the sample surface. The results show that modeling of the spatial configurations of laser excitation and detection points can be used to optimize the instrument configuration to achieve significant improvements (up to 2.25-fold) in performance over the conventional centered SORS. Such optimal solutions can then be implemented, for example, using robust fiber optic probes, moveable optics, or flexible spatial light modulator instruments for specific applications.

Thiolene- and Polycaprolactone Methacrylate-Based Polymerized High Internal Phase Emulsion (PolyHIPE) Scaffolds for Tissue Engineering

Highly porous emulsion templated polymers (PolyHIPEs) provide a number of potential advantages in the fabrication of scaffolds for tissue engineering and regenerative medicine. Porosity enables cell ingrowth and nutrient diffusion within, as well as waste removal from, the scaffold. The properties offered by emulsion templating alone include the provision of high interconnected porosity, and, in combination with additive manufacturing, the opportunity to introduce controlled multiscale porosity to complex or custom structures. However, the majority of monomer systems reported for PolyHIPE preparation are unsuitable for clinical applications as they are nondegradable. Thiol-ene chemistry is a promising route to produce biodegradable photocurable PolyHIPEs for the fabrication of scaffolds using conventional or additive manufacturing methods; however, relatively little research has been reported on this approach. This study reports the groundwork to fabricate thiol- and polycaprolactone (PCL)-based PolyHIPE materials via a photoinitiated thiolene click reaction. Two different formulations, either three-arm PCL methacrylate (3PCLMA) or four-arm PCL methacrylate (4PCLMA) moieties, were used in the PolyHIPE formulation. Biocompatibility of the PolyHIPEs was investigated using human dermal fibroblasts (HDFs) and human osteosarcoma cell line (MG-63) by DNA quantification assay, and developed PolyHIPEs were shown to be capable of supporting cell attachment and viability.

649 Smoking Cessation as A Variable Risk Factor in Head and Neck Cancer

Aim

Smoking is the leading cause of preventable death and disability worldwide and is a well understood risk factor in a number of diseases, including cancers of the head and neck. In 2019 over half of UK smokers reported interest in quitting, however, continue to do so. We assessed referrals made to the cessation service by the Ear Nose & Throat (ENT) department across the health board with the aim of raising awareness and improving smoking cessation referrals.

Method

Working with the smoking cessation team, we retrospectively assessed the clinical information of all patients referred by ENT over an 8-month period during 2019. The results of which, were presented departmentally with the goal of raising awareness of the service. Posters were also created detailing the referral process to aid junior doctors on surgical wards. Data was then re-audited over the subsequent 9-month period.

Results

Initially, 33 patients were referred over the first 8-month period, averaging 4 per month with 44% of patients already having laryngeal cancer. After our interventions, the total number of referrals increased with 74 over the 9-month period, averaging 8 referrals per month with 28% of patients having laryngeal cancer association.

Conclusions

Overall, there was a significant 135% increase in the number of referrals made, both cancer and non-cancer. The increase made in monthly referrals suggests a sustainable change. The percentage decrease of cancer patients referred and overall increase in number of referrals, represents the reduction of smoking being a risk factor of developing laryngeal cancer in ENT patients.

Heartworm control in Grenada, West Indies: Results of a field study using imidacloprid 10% + moxidectin 2.5% and doxycycline for naturally-acquired Dirofilaria immitis infections

Canine heartworm disease (CHD) results from infection with Dirofilaria immitis and while it is of global concern, it is most prevalent in tropical climates where conditions support the parasite and vector life cycles. Melarsomine dihydrochloride is the sole treatment for CHD recommended by the American Heartworm Society. However, in cases where cost or access to melarsomine precludes treatment of an infected dog, therapeutic alternatives are warranted. This randomized, controlled field study evaluated the adulticidal efficacy of a combination therapeutic protocol using 10 % imidacloprid + 2.5 % moxidectin spot-on and a single 28-day course of doxycycline and compared with that of a 2-dose melarsomine dihydrochloride protocol. Of 37 naturally-infected domestic dogs with class 1, 2 or early class 3 CHD enrolled in the study, 30 were evaluated for a minimum of 12 months. Seven dogs were withdrawn due to canine ehrlichiosis, non-compliance, or wrongful inclusion. Dogs were randomly assigned to a control (CP, n = 15) or investigational (IVP, n = 15) treatment group. CP dogs received two injections of melarsomine dihydrochloride (2.5 mg/kg) 24 -hs apart and maintained on monthly ivermectin/pyrantel. IVP dogs were treated with oral doxycycline (10 mg/kg twice daily for 28 days) and topical 10 % imidacloprid + 2.5 % moxidectin once monthly for 9 months. Dogs were evaluated up to 18 months - monthly for the first 9 months, then every 3 months. Parasiticidal efficacy was based on antigen status using the IDEXX PetChek® 34 Heartworm-PF Antigen test. By month 18, antigen was not detected in any study dog except one from the IVP group. One other IVP dog was persistently antigenemic and treated with melarsomine at month 12 according to the initial study protocol. Mean antigen concentration (based on optical density) decreased more rapidly in the CP group and by month 15 was 0.11 for the IVP and 0.07 for CP groups, with equivalent median concentrations (0.04) in both groups. Conversion following heat-treatment of antigen-negative samples occurred frequently and at similar rates in both treatment groups. Based on the bias of diagnostic tests towards detection of female worms, we conclude that monthly application of 10 % imidacloprid + 2.5 % moxidectin for 9 months combined with a course of doxycycline twice daily for 28 days resulted in effective therapy against female adults in CHD. This therapeutic option may be particularly useful in cases where financial constraint or access to melarsomine precludes treatment of an infected individual. This study was supported by Bayer Animal Health.

Osteosarcoma growth on trabecular bone mimicking structures manufactured via laser direct write

This paper describes the direct laser write of a photocurable acrylate-based PolyHIPE (High Internal Phase Emulsion) to produce scaffolds with both macro- and microporosity, and the use of these scaffolds in osteosarco-ma-based 3D cell culture. The macroporosity was introduced via the application of stereolithography to produce a clas-sical woodpile structure with struts having an approximate diameter of 200 ?m and pores were typically around 500 ?m in diameter. The PolyHIPE retained its microporosity after stereolithographic manufacture, with a range of pore sizes typically between 10 and 60 ?m (with most pores between 20 and 30 ?m). The resulting scaffolds were suitable substrates for further modification using acrylic acid plasma polymerisation. This scaffold was used as a structural mimic of the trabecular bone and in vitro determination of biocompatibility using cultured bone cells (MG63) demon-strated that cells were able to colonise all materials tested, with evidence that acrylic acid plasma polymerisation im-proved biocompatibility in the long term. The osteosarcoma cell culture on the 3D printed scaffold exhibits different growth behaviour than observed on tissue culture plastic or a flat disk of the porous material; tumour spheroids are ob-served on parts of the scaffolds. The growth of these spheroids indicates that the osteosarcoma behave more akin to in vivo in this 3D mimic of trabecular bone. It was concluded that PolyHIPEs represent versatile biomaterial systems with considerable potential for the manufacture of complex devices or scaffolds for regenerative medicine. In particular, the possibility to readily mimic the hierarchical structure of native tissue enables opportunities to build in vitro models closely resembling tumour tissue.

Emulsion templated scaffolds with tunable mechanical properties for bone tissue engineering

Polymerised High Internal Phase Emulsions (PolyHIPEs) are manufactured via emulsion templating and exhibit a highly interconnected microporosity. These materials are commonly used as thin membranes for 3D cell culture. This study uses emulsion templating in combination with microstereolithography to fabricate PolyHIPE scaffolds with a tightly controlled and reproducible architecture. This combination of methods produces hierarchical structures, where the microstructural properties can be independently controlled from the scaffold macrostructure. PolyHIPEs were fabricated with varying ratios of two acrylate monomers (2-ethylhexyl acrylate (EHA) and isobornyl acrylate (IBOA)) and varying nominal porosity to tune mechanical properties. Young's modulus, ultimate tensile stress (UTS) and elongation at failure were determined for twenty EHA/IBOA compositions. Moduli ranged from 63.01±9.13 to 0.36±0.04MPa, UTS from 2.03±0.33 to 0.11±0.01MPa and failure strain from 21.86±2.87% to 2.60±0.61%. Selected compositions were fabricated into macro-porous woodpile structures, plasma treated with air or acrylic acid and seeded with human embryonic stem-cell derived mesenchymal progenitor cells (hES-MPs). Confocal and two-photon microscopy confirmed cell proliferation and penetration into the micro- and macro-porous architecture. The scaffolds supported osteogenic differentiation of mesenchymal cells and interestingly, the stiffest IBOA-based scaffolds that were plasma treated with acrylic acid promoted osteogenesis more strongly than the other scaffolds.

Combination of microstereolithography and electrospinning to produce membranes equipped with niches for corneal regeneration

Corneal problems affect millions of people worldwide reducing their quality of life significantly. Corneal disease can be caused by illnesses such as Aniridia or Steven Johnson Syndrome as well as by external factors such as chemical burns or radiation. Current treatments are (i) the use of corneal grafts and (ii) the use of stem cell expanded in the laboratory and delivered on carriers (e.g., amniotic membrane); these treatments are relatively successful but unfortunately they can fail after 3-5 years. There is a need to design and manufacture new corneal biomaterial devices able to mimic in detail the physiological environment where stem cells reside in the cornea. Limbal stem cells are located in the limbus (circular area between cornea and sclera) in specific niches known as the Palisades of Vogt. In this work we have developed a new platform technology which combines two cutting-edge manufacturing techniques (microstereolithography and electrospinning) for the fabrication of corneal membranes that mimic to a certain extent the limbus. Our membranes contain artificial micropockets which aim to provide cells with protection as the Palisades of Vogt do in the eye.

Seroprevalence of Trypanosoma cruzi in stray and pet dogs in Grenada, West Indies

American trypanosomiasis (Chagas disease) caused by the protozoan parasite Trypanosoma cruzi is endemic to parts of South America and the Caribbean. Infected dogs are important in the epidemiology of the parasite as they can play a role in the transmission of the parasite to humans. A total of 399 dog sera (242 stray and 157 pet dogs) were examined for T. cruzi infection; using a qualitative immunochromatographic dipstick test, based on recombinant antigens specific for American trypanosomiasis (Trypanosoma detect rapid test; InBios international, Inc., Seattle, Washington). Overall seroprevalence for T. cruzi was estimated at 10.5% (95% confidence interval: 7.5% to 13.5%); with stray dogs being significantly more affected (p<0.05, χ2). Results from this study indicate that dogs in Grenada are moderately exposed to T. cruzi compared to other areas in the region.

Alternate virtual populations elucidate the type I interferon signature predictive of the response to rituximab in rheumatoid arthritis

Background

Mechanistic biosimulation can be used in drug development to form testable hypotheses, develop predictions of efficacy before clinical trial results are available, and elucidate clinical response to therapy. However, there is a lack of tools to simultaneously (1) calibrate the prevalence of mechanistically distinct, large sets of virtual patients so their simulated responses statistically match phenotypic variability reported in published clinical trial outcomes, and (2) explore alternate hypotheses of those prevalence weightings to reflect underlying uncertainty in population biology. Here, we report the development of an algorithm, MAPEL (Mechanistic Axes Population Ensemble Linkage), which utilizes a mechanistically-based weighting method to match clinical trial statistics. MAPEL is the first algorithm for developing weighted virtual populations based on biosimulation results that enables the rapid development of an ensemble of alternate virtual population hypotheses, each validated by a composite goodness-of-fit criterion.

Results

Virtual patient cohort mechanistic biosimulation results were successfully calibrated with an acceptable composite goodness-of-fit to clinical populations across multiple therapeutic interventions. The resulting virtual populations were employed to investigate the mechanistic underpinnings of variations in the response to rituximab. A comparison between virtual populations with a strong or weak American College of Rheumatology (ACR) score in response to rituximab suggested that interferon β (IFNβ) was an important mechanistic contributor to the disease state, a signature that has previously been identified though the underlying mechanisms remain unclear. Sensitivity analysis elucidated key anti-inflammatory properties of IFNβ that modulated the pathophysiologic state, consistent with the observed prognostic correlation of baseline type I interferon measurements with clinical response. Specifically, the effects of IFNβ on proliferation of fibroblast-like synoviocytes and interleukin-10 synthesis in macrophages each partially counteract reductions in synovial inflammation imparted by rituximab. A multianalyte biomarker panel predictive for virtual population therapeutic responses suggested population dependencies on B cell-dependent mediators as well as additional markers implicating fibroblast-like synoviocytes.

Conclusions

The results illustrate how the MAPEL algorithm can leverage knowledge of cellular and molecular function through biosimulation to propose clear mechanistic hypotheses for differences in clinical populations. Furthermore, MAPEL facilitates the development of multianalyte biomarkers prognostic of patient responses in silico.

Genotypechecker: an interactive tool for checking the inheritance consistency of genotyped pedigrees

Datapoint errors in pedigree genotype data sets are difficult to identify and adversely affect downstream genetic analyses. We present GenotypeChecker, a desktop software tool for assisting data cleansing. The application identifies likely data errors in pedigree/genotype data sets by performing an inheritance-checking algorithm for each marker across the pedigree, and highlights inconsistently inherited genotypes in an exploratory user interface. By 'masking' suspect datapoints and rechecking inheritance consistency, erroneous datapoints can be confirmed and cleansed from the data set. The software, examples and documentation are freely available at http://bioinformatics.roslin.ac.uk/genotypechecker.

Standard data model representation for taxonomic information

The names used by biologists to label the observations they make are imprecise. This is an issue as workers increasingly seek to exploit data gathered from multiple, unrelated sources on line. Even when the international codes of nomenclature are followed strictly the resulting names (Taxon Names) do not uniquely identify the taxa (Taxon Concepts) that have been described by taxonomists but merely groups of type specimens. A standard data model for exchange of taxonomic information is described. It addresses this issue by facilitating explicit communication of information about Taxon Concepts and their associated names. A representation of this model as a XML Schema is introduced and the implications of the use of Globally Unique Identifiers discussed.

Gene transfer to primary acute myeloid leukaemia blasts and myeloid leukaemia cell lines

The transfer of genes encoding co-stimulatory molecules and/or cytokines to leukaemia cells in order to create autologous tumour vaccines represents a potential immunotherapeutic strategy for treating acute myeloid leukaemia (AML). One of the essential requirements for this strategy if it is to be applicable in a clinical setting is a high efficiency of gene transfer to primary human AML blasts. Using green fluorescent protein (GFP) as a reporter gene, we have systematically evaluated a variety of physical, chemical and viral vector-based gene transfection systems in order to determine which gave the highest gene transfer efficiency to myeloid leukaemia cell lines and primary AML blasts. Transfection efficiency was low for all the physical and chemical transfection methods tested. Retroviral vector-based infection gave a high efficiency of gene transduction in two of the four leukaemia cell lines (KG1a and U937), but was low in primary AML blasts. An adenoviral vector gave a high transduction efficiency in all of the leukaemia cell lines with the exception of the HL60. In primary AML blasts, derived from 19 patients, gene transduction efficiency was variable, ranging from 1.1% to 67.1% (mean 12.1%). Following culture in cytokines GM-CSF/IL-4/CD40L, which induced differentiation of AML blasts to dendritic-like cells, transduction efficiency was increased between two- and eightfold in 6 out of the 15 cases that underwent differentiation.

Role for CD40-CD40 ligand interactions in the immune response to solid tumours

CD40-mediated interactions play an important role in the response to infections, transplantation, and cancer by affecting the development, activation, proliferation and differentiation of a variety of immune cells. In the current study we examined the role of CD40-mediated interactions in immune responses to bladder, pancreatic and breast carcinomas as well as melanoma cell lines using soluble human CD40L (rhCD40L) or anti-CD40 mAb in vitro. CD40 expression was readily detected in a large proportion of the cell lines and was augmented but not induced de novo by treatment with IFNgamma. Treatment of CD40-positive cell lines with rhCD40L or anti-CD40mAb enhanced cell surface expression of ICAM-1 and FAS and stimulated the production of IL-6, IL-8, GROalpha, GM-CSF and TNFalpha but not IL-4, IL-10, TGFbeta, MCP-1, RANTES, MIP-1beta, or IP-10. In addition, incubation of CD40+ tumour cell lines with immobilised rhCD40L or anti-CD40 mAb in vitro resulted in significant inhibition of proliferation and a corresponding decrease in viability. This CD40-mediated inhibition of cell growth was due, at least in part, to alterations in cell cycle and the induction of apoptosis. Transfection of CD40-negative tumour cell lines with the cDNA for CD40 conferred responsiveness to rhCD40L and anti-CD40 antibody. Finally, the presence of CD40 on the surface of carcinoma lines was found to be an important factor in the generation of tumour-specific T cell responses.

Variation in IgG1 heavy chain allotype does not contribute to differences in biological activity of two human anti-Rhesus (D) monoclonal antibodies

BACKGROUND

Pooled human anti-Rhesus D antiserum is currently administered for the prevention of RhD alloimmunization. Increased demand, and decreased supply, of donated pooled antiserum has led to the investigation of the suitability of human monoclonal anti-RhD antibodies for use in its place. However, it is unclear which biological properties of monoclonal antibodies are important for function in RhD-positive foetal red cell clearance and the prevention of alloimmunization. Various antibodies behave differently in a number of in vitro assays of biological function.

OBJECTIVES

To compare the function and structure of two human anti-RhD IgG1 monoclonal antibodies which differ in their ability to promote red cell lysis in vitro. In particular to examine whether the functional differences correlate to differences in the IgG1 heavy chain constant region (allotype).

STUDY DESIGN

We report here the cloning, characterization and re-expression in stable myeloma cell transformants of cDNAs coding for two such antibodies, secreted by the heterohybridoma cell lines ESD-1 (THERAD 03) and LHM 70/45.3 (THERAD 06). The cDNAs were then recombined to exchange portions of the Fc encoding regions and the recombinant antibodies were assayed in vitro to determine RhD-positive red cell-dependent activity.

RESULTS

Recombinant THERAD 03 and 06 antibodies behaved identically to the parent antibodies. The 'inactive' THERAD 06 did not have biological activity reconstituted by exchange with the THERAD 03 Fc regions, nor was THERAD 03 activity abolished by the reciprocal Fc region exchange.

CONCLUSIONS

Human monoclonal anti-RhD antibodies can be cloned and re-expressed in stable cell lines, and exhibit identical properties to the parent antibodies. Differences in biological activity cannot be attributed to differences in IgG1 heavy chain allotype.

A LINE-like transposable element in Drosophila, the I factor, encodes a protein with properties similar to those of retroviral nucleocapsids

I factors are members of the LINE-like family of transposable elements and move by reverse transcription of an RNA intermediate. Complete I factors contain two open reading frames. The amino acid sequence encoded by the first of these, ORF1, includes the motif CX2CX4HX4C that is characteristic of the nucleocapsid domain of retroviral gag polypeptides followed by a copy of the slightly different sequences CX2CX4HX6C and CX2CX9HX6C. The function of this protein is unknown. We have expressed this protein in Escherichia coli and Spodoptera frugiperda cells and have shown that it binds both DNA and RNA but without any evidence for sequence specificity. The properties of deletion derivatives of the protein indicate that more than one region is responsible for DNA binding and that the CCHC motif is not essential for this. The ORF1 protein expressed in either E. coli or Spodoptera cells forms high molecular weight structures that require the region of the protein including the CCHC motif for their formation. This protein can also accelerate the annealing of complementary single-stranded oligonucleotides. These results suggest that this protein may associate with the RNA transposition intermediates of the I factor to form particles that enter the nucleus during transposition and that it may stimulate both the priming of reverse transcription and integration. This may be generally true for the product of the first open reading frame of LINE-like elements.

The expression and characterization of five recombinant murine alpha 1-protease inhibitor proteins

The Mus musculus alpha 1-protease inhibitor gene cluster encodes five highly related proteins. The most significant amino acid polymorphisms lie within the reactive-site loop which is important in determining serpin substrate specificity. All five genes are transcribed in M. musculus adult liver and presumably secreted into plasma. In an attempt to characterize their protein products all five cDNAs were expressed in recombinant mammalian cells and the protease inhibition activity of each determined. Only two of the proteins were efficient inhibitors of neutrophil elastase, the major physiological target of the sole human alpha 1-protease inhibitor (antitrypsin). Four of the proteins were active against chymotrypsin, while no substrate could be identified for the fifth.

Approaches to maximizing stable expression of alpha 1-antitrypsin in transformed CHO cells

A variety of approaches to maximizing the production of recombinant human alpha 1-antitrypsin (AAT) in Chinese hamster ovary (CHO) cells have been investigated. The highly active and inducible human cytomegalovirus immediate early (IE) promoter/enhancer was used to drive transcription of a recombinant AAT gene in transiently transfected and stably transformed CHO cells. The AAT gene was modified to incorporate highly efficient 3'RNA processing signals from the herpes simplex virus type 2 IE gene 5, and optimal translational initiation signals were created by site-directed mutagenesis. The effect of flanking the recombinant gene with matrix attachment regions was investigated. Combinations of these modifications allowed secretion of up to 44 micrograms AAT/ml per day by cell lines growing in serum-rich medium. This could be increased to up to 100 micrograms AAT/ml per day upon chemical induction of expression by propionate, butyrate or hexamethylene bisacetamide. Cell lines adapted to grow in protein-free medium produced less AAT but still responded to chemical induction to secrete up to 14 micrograms/ml per day of readily purified AAT.

Polypeptide components of Drosophila small nuclear ribonucleoprotein particles

In eukaryotes splicing of pre-mRNAs is mediated by the spliceosome, a dynamic complex of small nuclear ribonucleoprotein particles (snRNPs) that associate transiently during spliceosome assembly and the splicing reaction. We have purified snRNPs from nuclear extracts of Drosophila cells by affinity chromatography with an antibody specific for the trimethylguanosine (m3G) cap structure of snRNAs U1-U5. The polypeptide components of Drosophila snRNPs have been characterized and shown to consist of a number of proteins shared by all the snRNPs, and some proteins which appear to be specific to individual snRNP particles. On the basis of their apparent molecular weight and antigenicity many of these common and particle specific Drosophila snRNP proteins are remarkably conserved between Drosophila and human spliceosomes. By probing western blots of the Drosophila snRNP polypeptides with a number of antisera raised against human snRNP proteins, Drosophila polypeptides equivalent to many of the HeLa snRNP-common proteins have been identified, as well as candidates for a number of U1, U2 and U5-specific proteins.

The major transcriptional regulatory protein of herpes simplex virus type 1 includes a protease resistant DNA binding domain

Herpes simplex virus type 1 expresses five immediate-early (IE) polypeptides. In the absence of functional Vmw175 (the product of IE gene 3) activation of transcription of later classes of viral genes and repression of IE gene expression does not occur. The recognition of specific DNA sequences by Vmw175 requires, as determined by sensitivity to mutation, a part of the protein highly conserved in the corresponding proteins of related herpes viruses. However, mutations in other parts of the protein can also disrupt specific DNA binding. This paper shows that the DNA binding domain of Vmw175 can be liberated as a functional unit by digestion with proteinase K. Analysis of mutant Vmw175 proteins showed that the proteinase K resistant domain has an amino terminus between amino acid residues 229 and 292, while its carboxy terminus is between residues 495 and 518. Mutations outside this region which affect DNA binding by the intact protein do not eliminate binding of the proteinase K resistant domain. This implies that direct DNA binding by Vmw175 involves a linear subsection of the polypeptide, and that mutations in other parts of the polypeptide which affect DNA binding of the whole protein do so by indirect means.

A prominent serine-rich region in Vmw175, the major transcriptional regulator protein of herpes simplex virus type 1, is not essential for virus growth in tissue culture

Herpes simplex virus type 1 (HSV-1) encodes five immediate early (IE) genes of which at least three are involved in the transcriptional regulation of later classes of viral genes. Perhaps the most important of these regulatory proteins is Vmw175, a nuclear phosphoprotein of 1298 predicted amino acid residues. In the absence of functional Vmw175 the virus fails to activate early or late genes or to repress IE gene expression. All viruses of the sub-family alphaherpes-virinae encode polypeptides that are closely related to Vmw175. Mutational studies have shown that regions of homology within this family of gene regulators are generally of functional importance. One of the most striking conserved stretches of amino acid sequence is a run of serine residues followed by a highly acidic region in the amino-terminal fifth of the polypeptide. We have constructed an HSV-1 virus which lacks this serine-rich run within Vmw175. Surprisingly, the virus was viable in tissue culture cells and expressed apparently normal amounts of viral polypeptides. In plaque assays it was very slightly temperature-sensitive and, depending on the state of the host cells, could generate plaques with a syncytial morphology. The mutant protein was able to bind to DNA in a manner indistinguishable from that of the wild-type polypeptide. We conclude that despite its conservation in all of the alphaherpes-virinae so far sequenced, the serine-rich homology is not important for virus growth in tissue culture.

A mutant of herpes simplex virus type 1 immediate early polypeptide Vmw175 binds to the cap site of its own promoter in vitro but fails to autoregulate in vivo

Vmw175, the product of herpes simplex virus type 1 immediate early (IE) gene 3, is essential for viral replication. It is required for the activation of transcription from both early and late gene promoters and also for the repression of IE gene expression. Vmw175 is able to bind specifically to certain DNA sequences, some of which (including that at the cap site of IE gene 3) contain the consensus sequence ATCGTC. The presence of this sequence at the cap site has been correlated with the ability of Vmw175 to autoregulate its own promoter. This report describes the characterization of five viruses with temperature-sensitive (ts) lesions in Vmw175. Four of these mutants express Vmw175 which is ts in its ability to bind to DNA in vitro and to autoregulate IE-3 gene expression in the infected cell. Although Vmw175 produced by the remaining mutant, ts1225, fails to autoregulate IE-3 expression at the non-permissive temperature (NPT) its DNA-binding properties are indistinguishable from those of the wild-type protein. This suggests that the ability of Vmw175 to bind to the IE-3 cap site (as measured in vitro) is insufficient for autoregulation (in vivo). All five newly characterized ts mutants are partially permissive for early gene transcription at the NPT, although Vmw175 expressed by four of them is unable to bind to the IE-3 cap site sequence at elevated temperatures. This suggests that binding to one class of recognition sequences by Vmw175, as measured in vitro, is not absolutely required for the activation of early gene promoters during virus infection. The lesions in these five ts mutants lie in the carboxy-terminal third of the polypeptide; three of the mutations (those in ts1219, ts1221 and ts1225) were identified by DNA sequence analysis and were found to affect amino acid residues that are conserved in the homologous proteins from varicella-zoster virus and pseudorabies virus.

The effect of DnaA protein levels and the rate of initiation at oriC on transcription originating in the ftsQ and ftsA genes: in vivo experiments

The DnaA protein of Escherichia coli, essential for initiation at oriC, binds at a defined sequence which occurs at the chromosomal origin, near plasmid replication origins and in the promoters of the dnaA and mioC genes. This sequence also occurs at many other sites on the E. coli chromosome including three sites within the essential cell division genes ftsQ and A. Using an fts-lac fusion phage, lambda JFL100, we show here that fts gene expression responds both to reduced and increased intracellular levels of DnaA protein in a manner consistent with the hypothesis that DnaA protein regulates fts gene expression. Experiments using dnaC and dnaB-ts strains, however, suggest that DnaA control of fts transcription may be indirect, at least in part, with fts responding to the rate of initiation at oriC as well as to changes in DnaA protein level per se. It differs in this respect from dnaA gene expression which is unaffected when initiation of replication is inhibited by DnaB or DnaC inactivation. Strains integratively suppressed with pKN500 behave anomalously; neither fts nor dnaA transcription is significantly increased when DnaA is inactivated in these strains.

The regions of the herpes simplex virus type 1 immediate early protein Vmw175 required for site specific DNA binding closely correspond to those involved in transcriptional regulation

The immediate-early (IE) protein Vmw175 (ICP4) of HSV-1 is required for the transcription of later classes of viral genes and the repression of IE gene expression. We have previously constructed a panel of plasmid-borne insertion and deletion mutants of the gene encoding Vmw175 and assayed their ability to regulate transcription in transient transfection assays. By this approach we have mapped the regions of the Vmw175 amino acid sequence that are required for transcriptional activation and repression of herpes virus promoters. This paper describes the use of nuclear extracts, made from cells transfected with these mutant plasmids, in gel retardation DNA binding assays in order to define the regions of Vmw175 involved in binding to a specific Vmw175 DNA binding site. The results show that amino acid residues 275-495 (a region which is highly conserved between Vmw175 and the varicella-zoster virus "IE" 140K protein) include structures which are critically required for specific DNA binding, transactivation and repression. This raises the interesting paradox that although the specific DNA sequence recognized by Vmw175 is not commonly found in its target promoters, the protein domain required for recognition of this sequence is required for promoter activation.

Mutational dissection of the HSV-1 immediate-early protein Vmw175 involved in transcriptional transactivation and repression

Vmw175 is one of five immediate-early (IE) proteins encoded by herpes simplex virus type-1 (HSV-1). It is required for the transcription of later classes of genes and for the accompanying repression of IE expression. Vmw175 has been shown to be a transactivator of transcription and also to autoregulate its own synthesis. We have made a large number of small, in-frame, insertion and deletion mutants of a plasmid-borne copy of the gene encoding Vmw175. Study of the activity of the resultant mutant polypeptides in transient transfection assays has defined the regions of the protein important for the repression of its own promoter, and for the transactivation of an HSV early promoter in synergy with another HSV IE protein, Vmw110. Large stretches of the protein are relatively unimportant for either function, while the regions most sensitive to disruption correlate to sequences conserved between Vmw175 and VZV 140K, the corresponding transactivating protein of Varicella-Zoster virus. The region from amino acids 275 to 490 is particularly important for both repression and transactivation, whereas that from around 840 to 1100 seems to be more important for transactivation than repression. The nuclear localization signal has been mapped to within residues 682-774.

2,4-diamino-5-benzylpyrimidines and analogues as antibacterial agents. 6. A one-step synthesis of new trimethoprim derivatives and activity analysis by molecular modeling

A new route to 2,4-diamino-5-(4-hydroxybenzyl)pyrimidines has been developed that involves the condensation of 2,4-diamino-5-(hydroxymethyl)pyrimidine with phenols in acidic medium. The use of phenol and its 2,6-dialkyl derivatives produces 5-(4-hydroxybenzyl)pyrimidines exclusively. However, 2,6-dimethoxyphenol produces a mixture of 5-(3-hydroxy-2,4-dimethoxybenzyl)- and 5-(4-hydroxy-3,5-dimethoxybenzyl)pyrimidines. The phenolic condensation has been used to prepare a series of alkyl-substituted 5-(4-hydroxybenzyl)- and 5-(4-alkoxybenzyl)pyrimidines. The use of 1,2,3-trimethoxybenzene in place of a phenol produces 2,4-diamino-5-(2,3,4-trimethoxybenzyl)pyrimidine, a trimethoprim isomer with low antibacterial activity. The use of molecular models of several of the new ortho-substituted derivatives in the active site of dihydrofolate reductase has provided a rational explanation for their activities relative to trimethoprim.