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Biomedical subjects

J M Ward

Publications and source records attributed to J M Ward.

At least 19 recordsLinked to original sources
PubMed2007

Degradation of supercoiled plasmid DNA within a capillary device.

Supercoiled plasmid DNA is susceptible to fluid stress in large-scale manufacturing processes. A capillary device was used to generate controlled shear conditions and the effects of different stresses on plasmid DNA structure were investigated. Computational fluid dynamics (CFD) analysis was employed to characterize the flow environment in the capillary device and different analytical techniques were used to quantify the DNA breakage. It was found that the degradation of plasmid DNA occurred at the entrance of the capillary and that the shear stress within the capillary did not affect the DNA structure. The degradation rate of plasmids was well correlated with the average elongational strain rate or the pressure drop at the entrance region. The conclusion may also be drawn that laminar shear stress does not play a significant role in plasmid DNA degradation.

Computer Simulation↗
PubMed2007

One-pot synthesis of amino-alcohols using a de-novo transketolase and beta-alanine: pyruvate transaminase pathway in Escherichia coli.

Biocatalysis continues to emerge as a powerful technique for the efficient synthesis of optically pure pharmaceuticals that are difficult to access via conventional chemistry. The power of biocatalysis can be enhanced if two or more reactions can be achieved by a single whole cell biocatalyst containing a pathway designed de-novo to facilitate a required synthetic sequence. The enzymes transketolase (TK) and transaminase (TAm) respectively catalyze asymmetric carbon--carbon bond formation and amine group addition to suitable substrate molecules. The ability of a transaminase to accept the product of the transketolase reaction can allow the two catalysts to be employed in series to create chiral amino-alcohols from achiral substrates. As proof of principle, the beta-alanine: pyruvate aminotransferase (beta-A:P TAm) from Pseudomonas aeruginosa has been cloned, to create plasmid pQR428, for overexpression in E.coli strain BL21gold(DE3). Production of the beta-A:P TAm alongside the native transketolase (overexpressed from plasmid pQR411), in a single E.coli host, has created a novel biocatalyst capable of the synthesis of chiral amino alcohols via a synthetic two-step pathway. The feasibility of using the biocatalyst has been demonstrated by the formation of a single diastereoisomer of 2-amino-1,3,4-butanetriol (ABT) product, in up to 21% mol/mol yield, by the beta-A:P TAm, via transamination of L-erythrulose synthesized by TK, from achiral substrates glycolaldehyde (GA) and beta-hydroxypyruvate (beta-HPA). ABT synthesis was achieved in a one-pot process, using either whole cells of the dual plasmid strain or cell lysate, while the dual alcohol-amine functionality of ABT makes it an excellent synthon for many pharmaceutical syntheses.

Amino Alcohols↗
PubMed2006

Plasmodium falciparum-infected erythrocytes induce tissue factor expression in endothelial cells and support the assembly of multimolecular coagulation complexes.

BACKGROUND: Plasmodium falciparum malaria infects 300-500 million people every year, causing 1-2 million deaths annually. Evidence of a coagulation disorder, activation of endothelial cells (EC) and increase in inflammatory cytokines are often present in malaria. OBJECTIVES: We have asked whether interaction of parasitized red blood cells (pRBC) with EC induces tissue factor (TF) expression in vitro and in vivo. The role of phosphatidylserine-containing pRBC to support the assembly of blood coagulation complexes was also investigated. RESULTS: We demonstrate that mature forms of pRBC induce functional expression of TF by EC in vitro with productive assembly of the extrinsic Xnase complex and initiation of the coagulation cascade. Late-stage pRBC also support the prothrombinase and intrinsic Xnase complex formation in vitro, and may function as activated platelets in the amplification phase of the blood coagulation. Notably, post-mortem brain sections obtained from P. falciparum-infected children who died from cerebral malaria and other causes display a consistent staining for TF in the EC. CONCLUSIONS: These findings place TF expression by endothelium and the amplification of the coagulation cascade by pRBC and/or activated platelets as potentially critical steps in the pathogenesis of malaria. Furthermore, it may allow investigators to test other therapeutic alternatives targeting TF or modulators of EC function in the treatment of malaria and/or its complications.

Adolescent↗
PubMed2006

Eosinophilic crystalline pneumonia as a major cause of death in 129S4/SvJae mice.

Eosinophilic crystalline pneumonia is an idiopathic disease that occurs in many strains and stocks of mice, more commonly in strains on a C57BL/6 background. The disease occurs sporadically in most strains of mice and varies from mild and subclinical to severe and fulminating, sometimes resulting in respiratory distress and death. In this study, 94 aged male and female 129S4/SvJae mice were evaluated for eosinophilic crystalline pneumonia lesions. There was an 87% incidence, with females overrepresented. Histologically, there were multifocal to coalescing inflammatory infiltrates composed of numerous large eosinophilic macrophages and multinucleate cells admixed with eosinophils, neutrophils, lymphocytes, and plasma cells within alveolar and bronchiolar spaces, associated with refractile, brightly eosinophilic, angular crystals. Alveolar macrophages and multinucleate cells contained fine needlelike to rectangular intracytoplasmic crystalline material. Similar crystals were often free within alveoli and conducting airways, often associated with mucous metaplasia of bronchiolar epithelium. This disease may occur spontaneously or in concert with other pulmonary lesions, such as pulmonary adenomas, lymphoproliferative disease, allergic pulmonary disease, and parasitic or fungal infections. The characteristic crystals morphologically resemble Charcot-Leyden crystals, which represent eosinophil breakdown products in humans with eosinophil-related disease. However, crystals in eosinophilic crystalline pneumonia are composed predominantly of Ym1 protein, a chitinase-like protein associated with neutrophil granule products and secreted by activated macrophages. The function of Ym1 protein is not fully understood but is believed to be involved in host immune defense, eosinophil recruitment, and cell-cell and cell-matrix interactions consistent with tissue repair. The mechanism of induction of eosinophilic crystalline pneumonia with Ym1 crystal formation is unknown.

Aging↗
PubMed2005

Bioinformatics approaches for cross-species liver cancer analysis based on microarray gene expression profiling.

BACKGROUND: The completion of the sequencing of human, mouse and rat genomes and knowledge of cross-species gene homologies enables studies of differential gene expression in animal models. These types of studies have the potential to greatly enhance our understanding of diseases such as liver cancer in humans. Genes co-expressed across multiple species are most likely to have conserved functions. We have used various bioinformatics approaches to examine microarray expression profiles from liver neoplasms that arise in albumin-SV40 transgenic rats to elucidate genes, chromosome aberrations and pathways that might be associated with human liver cancer. RESULTS: In this study, we first identified 2223 differentially expressed genes by comparing gene expression profiles for two control, two adenoma and two carcinoma samples using an F-test. These genes were subsequently mapped to the rat chromosomes using a novel visualization tool, the Chromosome Plot. Using the same plot, we further mapped the significant genes to orthologous chromosomal locations in human and mouse. Many genes expressed in rat 1q that are amplified in rat liver cancer map to the human chromosomes 10, 11 and 19 and to the mouse chromosomes 7, 17 and 19, which have been implicated in studies of human and mouse liver cancer. Using Comparative Genomics Microarray Analysis (CGMA), we identified regions of potential aberrations in human. Lastly, a pathway analysis was conducted to predict altered human pathways based on statistical analysis and extrapolation from the rat data. All of the identified pathways have been known to be important in the etiology of human liver cancer, including cell cycle control, cell growth and differentiation, apoptosis, transcriptional regulation, and protein metabolism. CONCLUSION: The study demonstrates that the hepatic gene expression profiles from the albumin-SV40 transgenic rat model revealed genes, pathways and chromosome alterations consistent with experimental and clinical research in human liver cancer. The bioinformatics tools presented in this paper are essential for cross species extrapolation and mapping of microarray data, its analysis and interpretation.

Animals↗
PubMed2003

A modified Escherichia coli protein production strain expressing staphylococcal nuclease, capable of auto-hydrolysing host nucleic acid.

The large-scale production of recombinant biotherapeutics, particularly recombinant proteins, provides significant process and regulatory challenges to the biotechnology industry in order to meet the regulatory agencies stringent requirements in a cost-effective manner. Host cell derived nucleic acid causes problems from both a process and a regulatory perspective, as high molecular weight chromosomal DNA is responsible both for the viscosity of cell lysates, and it is a source of heterologous DNA sequences whose inclusion in the final product must be prevented. We have constructed a modified Escherichia coli JM107 expression host (JMN), containing a staphylococcal nuclease expression cassette, integrated into the host chromosome at the dif locus. The nuclease is expressed as a fusion to the ompA signal peptide, and is translocated to the periplasm of the cell, protecting the cytoplasmic nucleic acid from any toxic activity. The nuclease is released during cell lysis, where it subsequently acts to hydrolyse host nucleic acid present in the lysate. Results with this strain show that sufficient levels of nuclease activity are produced to completely auto-hydrolyse the host's chromosomal DNA to a size non-visible on 1% agarose gel, generating a markedly lower lysate viscosity. This provides a suitable methodology to remove heterologous DNA sequences early in the product stream and decrease lysate viscosity, improving the efficiency of downstream processing and product yield, whilst avoiding the addition of exogenous nuclease and its prohibitive costs at large-scale.

Base Sequence↗
PubMed2002

A comparison of the process issues in expressing the same recombinant enzyme periplasmically in Escherichia coli and extracellularly in Streptomyces lividans.

The choice of a host for the production of a biological molecule will have a significant effect on isolation and purification procedures employed. This paper makes a comparison between the production of a single enzyme, a recombinant alpha-amylase, in Escherichia coli and Streptomyces lividans, on a small scale. It defines the differences in the cultivation and in the isolation stages and also describes the impact of the expression system on later downstream processing steps. At the cultivation stage, the specific productivity of the E. coli in units per gram per hour is four times that of the S. lividans while the total biomass yields are of the same order. The initial volume for downstream processing of S. lividans is six-fold larger and the total protein released into the extracellular medium is three times greater than E. coli, however, the recoverable yield from the E. coli is a fifth of that obtained from the S. lividans and requires three additional stages prior to chromatography. Even with these stages the final specific activity is 64% of the S. lividans. The results indicate the need to consider the whole process when making such comparisons.

Biomass↗
PubMed2002

Expression of the S. aureus hysA gene in S. carnosus from a modified E. coli-staphylococcal shuttle vector.

We have modified an E. coli-staphylococcal shuttle vector for use in the general cloning and expression of genes from pathogenic staphylococci in Staphylococcus carnosus. As S. carnosus is non-pathogenic, this expression system will facilitate the study of the roles of individual gene products in the disease process. To evaluate the use of this expression system, a DNA fragment containing the Staphylococcus aureus hyaluronate lyase (hysA) gene was cloned into the modified vector, pNW21, and introduced into S. carnosus. Hyaluronate lyase was both produced and secreted by S. carnosus. In addition, the secreted HysA protein was enzymatically active, as determined using a zymographic assay.

Base Sequence↗
PubMed2001

Systemic cancer therapy with a tumor-selective vaccinia virus mutant lacking thymidine kinase and vaccinia growth factor genes.

We have demonstrated previously the oncolytic effects of a systemically delivered, replicating vaccinia virus. To enhance the tumor specificity of this vector, we have developed a combined thymidine kinase-deleted (TK-) and vaccinia growth factor-deleted (VGF-) vaccinia virus and investigated its properties in vitro and in vivo. The gene for enhanced green fluorescent protein (EGFP) was inserted into the TK locus of a VGF- vaccinia virus by homologous recombination creating a double-deleted mutant vaccinia virus (vvDD-GFP). Infection of resting and dividing NIH3T3 cells with vvDD-GFP yielded reduced viral recovery compared with wild-type (WT), TK-, or VGF- viruses from resting cultures but equivalent virus recovery from dividing cultures. Eight days after nude mice were injected i.p. with 10(7) plaque-forming units (pfu) of WT, TK-, VGF-, or vvDD-GFP vaccinia virus, tissues and tumor were harvested for viral titer determination. No virus was recovered from the brains of mice injected with vvDD-GFP compared with the other viruses, which ranged from 130 to 28,000 pfu/mg protein; however, equivalent amounts were recovered from tumor. There was no toxicity from vvDD-GFP because nude mice receiving 10(8) pfu of IP vvDD-GFP lived >100 days, whereas mice receiving WT, VGF-, or TK- virus had median survivals of only 6, 17, and 29 days, respectively. Similar results were seen when 10(9) pfu of vvDD-GFP were given. Nude mice bearing s.c. murine colon adenocarcinoma (MC38) had significant tumor regression after treatment with 10(9) pfu of systemic (i.p.) vvDD-GFP compared with control (mean tumor size, 180.71 +/- 35.26 mm(3) versus 2796.79 +/- 573.20 mm(3) 12 days after injection of virus). Our data demonstrate that a TK- and VGF- mutant vaccinia virus is significantly attenuated in resting cells in vitro and demonstrates tumor-specific replication in vivo. It is a promising vector for use in tumor-directed gene therapy, given its enhanced safety profile, tumor selectivity, and the oncolytic effects after systemic delivery.

3T3 Cells↗
PubMed2001

Induction of transplantable mouse renal cell cancers by streptozotocin: in vivo growth, metastases, and angiogenic phenotype.

Interleukin-2-based regimens of biological therapy have shown some clinical promise for the treatment of kidney cancer in humans, although the mechanisms responsible for tumor regression occurring in these patients remain unclear. Preclinical insight into these mechanisms is limited by a paucity of orthotopic animal models of kidney cancer. We have used streptozotocin, an antibiotic and diabetogenic nitrosamine compound derived from Streptomyces achromogenes to induce new kidney tumors in BALB/c mice. Single or multiple doses of streptozotocin induced kidney tumors in up to 25% of mice by 50-90 weeks of age, with up to 18% characterized as renal cell carcinomas (RCCs). Several transplantable lines were obtained from the RCCs, and one of these lines was subsequently cloned. The initial tumor isolates and sublines were histologically reconfirmed to be RCCs, and all grew progressively but slowly (mean survival times, 57 to >100 days) in vivo after intrarenal implant. None of the primary isolates or sublines revealed mutations in either the VHL or Ras genes, although karyotype analysis and chromosome painting revealed the consistent presence of a submetacentric chromosome resulting from the fusion of chromosomes 16 and 19. Biological characterization of these tumors revealed several features analogous to the growth of human kidney cancers, including a propensity for the formation of lung metastases and high vascularity. This hypervascularity is evident by both gross and microscopic analysis and correlates with the expression of several proangiogenic genes. Overall, the features of orthotopic transplantability, slower in vivo growth (relative to the rapid growth rates of other transplantable mouse kidney tumors), propensity for lung metastases, and hypervascularity may make these tumors valuable models for the study of new therapeutic strategies based on antineovascular agents and antitumor cytokines.

Animals↗
PubMed2001

Peroxisome proliferator-activated receptor-alpha regulates lipid homeostasis, but is not associated with obesity: studies with congenic mouse lines.

Considerable controversy exists in determining the role of peroxisome proliferator-activated receptor-alpha (PPARalpha) in obesity. Two purebred congenic strains of PPARalpha-null mice were developed to study the role of this receptor in modulating lipid transport and storage. Weight gain and average body weight in wild-type and PPARalpha-null mice on either an Sv/129 or a C57BL/6N background were not markedly different between genotypes from 3 to 9 months of age. However, gonadal adipose stores were significantly greater in both strains of male and female PPARalpha-null mice. Hepatic accumulation of lipids was greater in both strains and sexes of PPARalpha-null mice compared with wild-type controls. Administration of the peroxisome proliferator WY-14643 caused hepatomegaly, alterations in mRNAs encoding proteins that regulate lipid metabolism, and reduced serum triglycerides in a PPARalpha-dependent mechanism. Constitutive differences in serum cholesterol and triglycerides in PPARalpha-null mice were found between genetic backgrounds. Results from this work establish that PPARalpha is a critical modulator of lipid homeostasis in two congenic mouse lines. This study demonstrates that disruption of the murine gene encoding PPARalpha results in significant alterations in constitutive serum, hepatic, and adipose tissue lipid metabolism. However, an overt, obese phenotype in either of the two congenic strains was not observed. In contrast to earlier published work, this study establishes that PPARalpha is not associated with obesity in mice.

Animals↗
PubMed2001

Eotaxin (CCL11) induces in vivo angiogenic responses by human CCR3+ endothelial cells.

Chemokines are attractants and regulators of cell activation. Several CXC family chemokine members induce angiogenesis and promote tumor growth. In contrast, the only CC chemokine, reported to play a direct role in angiogenesis is monocyte-chemotactic protein-1. Here we report that another CC chemokine, eotaxin (also known as CCL11), also induced chemotaxis of human microvascular endothelial cells. CCL11-induced chemotactic responses were comparable with those induced by monocyte-chemotactic protein-1 (CCL2), but lower than those induced by stroma-derived factor-1alpha (CXCL12) and IL-8 (CXCL8). The chemotactic activity was consistent with the expression of CCR3, the receptor for CCL11, on human microvascular endothelial cells and was inhibited by mAbs to either human CCL11 or human CCR3. CCL11 also induced the formation of blood vessels in vivo as assessed by the chick chorioallantoic membrane and Matrigel plug assays. The angiogenic response induced by CCL11 was about one-half of that induced by basic fibroblast factor, and it was accompanied by an inflammatory infiltrate, which consisted predominantly of eosinophils. Because the rat aortic sprouting assay, which is not infiltrated by eosinophils, yielded a positive response to CCL11, this angiogenic response appears to be direct and is not mediated by eosinophil products. This suggests that CCL11 may contribute to angiogenesis in conditions characterized by increased CCL11 production and eosinophil infiltration such as Hodgkin's lymphoma, nasal polyposis, endometriosis, and allergic diathesis.

Allantois↗
PubMed2001

Lsh, a SNF2 family member, is required for normal murine development.

Lsh is a member of the SNF2 family of chromatin remodelers, that regulate diverse biological processes such as replication, repair and transcription. Although expression of Lsh is highly tissue specific in adult animals, Lsh mRNA is detectable in multiple tissues during embryogenesis. In order to determine the physiologic role of Lsh during murine development and to assess its unique function in adult mice, we performed targeted deletion of the Lsh gene using homologous recombination in murine embryonic stem cells. Lsh-/- embryos occurred with the expected Mendelian frequency after implantation and during embryogenesis. However, Lsh-/- mice died within a few hours after birth. Furthermore, newborn mice were 22% lower in weight in comparison with their littermates and showed renal lesions. Thus Lsh is a non-redundant member of the SNF2 family and is essential for normal murine development and survival.

Animals↗
PubMed2001

Purification of essentially RNA free plasmid DNA using a modified Escherichia coli host strain expressing ribonuclease A.

Regulatory agencies have stringent requirements for the large-scale production of biotherapeutics. One of the difficulties associated with the manufacture of plasmid DNA for gene therapy is the removal of the host cell-related impurity RNA following cell lysis. We have constructed a modified Escherichia coli JM107 plasmid host (JMRNaseA), containing a bovine pancreatic ribonuclease (RNaseA) expression cassette, integrated into the host chromosome at the dif locus. The expressed RNaseA is translocated to the periplasm of the cell, and is released during primary plasmid extraction by alkaline lysis. The RNaseA protein is stable throughout incubation at high pH ( approximately 12-12.5), and subsequently acts to hydrolyse host cell RNA present in the neutralised solution following alkaline lysis. Results with this strain harbouring pUC18, and a 2.4 kb pUC18DeltalacO, show that sufficient levels of ribonuclease (RNase) activity are produced to hydrolyse the bulk of the host RNA. This provides a suitable methodology for the removal of RNA, whilst avoiding the addition of exogenous animal sourced RNase and its associated regulatory requirements.

Animals↗
PubMed2001

A mouse model of multiple endocrine neoplasia, type 1, develops multiple endocrine tumors.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant cancer syndrome, characterized primarily by multiple tumors in the parathyroid glands, endocrine pancreas, and anterior pituitary. Other tumors, including gastrinoma, carcinoid, adrenal cortical tumors, angiofibroma, collagenoma, and lipoma, also occur in some patients. Individuals with MEN1 almost always have loss-of-function mutations in the MEN1 gene on chromosome 11, and endocrine tumors arising in these patients usually show somatic loss of the remaining wild-type allele. To examine the role of MEN1 in tumor formation, a mouse model was generated through homologous recombination of the mouse homolog Men1. Homozygous mice die in utero at embryonic days 11.5-12.5, whereas heterozygous mice develop features remarkably similar to those of the human disorder. As early as 9 months, pancreatic islets show a range of lesions from hyperplasia to insulin-producing islet cell tumors, and parathyroid adenomas are also frequently observed. Larger, more numerous tumors involving pancreatic islets, parathyroids, thyroid, adrenal cortex, and pituitary are seen by 16 months. All of the tumors tested to date show loss of the wild-type Men1 allele, further supporting its role as a tumor suppressor gene.

Adenoma↗
PubMed2001

The restricted expression of granzyme M in human lymphocytes.

We have analyzed the expression of human granzyme M (Gzm M) in various human leukocyte subsets using the specific mAb 4H10. Using FACS and Western blotting analysis we compared the expression of Gzm M with that of other granzymes (Gzm A and Gzm B) and the lytic protein perforin. Human Gzm M was constitutively highly expressed in NK cells as was perforin and Gzm A. Surprisingly, freshly isolated NK cells had very low (sometimes undetectable) levels of Gzm B. In contrast to Gzm B and perforin, Gzm M was not detected in highly purified CD4(+) and CD8(+) T cells either constitutively or after short term activation in vitro. However, low levels of Gzm M were observed in some T cell clones on prolonged passage in vitro. Gzm M was not detected in highly purified neutrophils, monocytes, or tumor cells of the myelomonocytic lineage. Examination of minor T cell subsets from human peripheral blood showed detectable Gzm M in CD3(+), CD56(+) T cells and gammadelta T cells. A histological staining procedure was developed that demonstrated a granular staining pattern for Gzm M and a cellular distribution similar to that observed by Western blotting. These data indicate that the expression of Gzm M does not always correlate with the lytic activity of cytotoxic cells. However, expression of Gzm M in NK cells, CD3(+), CD56(+) T cells, and gammadelta T cells suggests that this enzyme may play some role in innate immune responses.

Blotting, Western↗
PubMed2001

Analysis of the effect of changing environmental conditions on the expression patterns of exported surface-associated proteins of the oral pathogen Actinobacillus actinomycetemcomitans.

Actinobacillus actinomycetemcomitans has been specifically implicated in the aetiology of one or more of the periodontal diseases, conditions in which inflammation of the gums is associated with destruction of the alveolar bone supporting the teeth. In these diseases there is loss of attachment of the gums (gingivae) to the teeth forming a periodontal pocket. The microenvironment of this pocket is extremely complex and it is likely that there will be substantial variation in the environmental conditions operating in this habitat. The aim of the current investigation was to study the effect of disease-relevant environmental factors on the production and release of secreted surface- associated proteins of A. actinomycetemcomitans. These secreted proteins contain many of the virulence determinants of this organism. A range of environmental conditions were investigated: growth in a CO(2)-enriched aerobic atmosphere vs anaerobic growth, presence of serum or blood, biofilm vs planktonic mode of growth and iron depletion. Differential expression of a number of the secreted surface-associated proteins was observed under different growth conditions and these included the glycolytic enzyme triose phosphate isomerase. An ability to adapt to prevailing environmental conditions may facilitate the survival of the organism in the changing microIenvironment of the periodontal pocket.

Adaptation, Biological↗