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Biomedical subjects

J A Harrison

Publications and source records attributed to J A Harrison.

At least 19 recordsLinked to original sources
PubMed2001

Crystallization and X-ray diffraction measurements on recombinant molbindin, MopII, from Clostridium pasteurianum.

Clostridium pasteurianum carries three genes termed mopI, II and III encoding three molbindin isoforms, one of which has been cloned, the gene product expressed in high yield and crystallized using the hanging-drop vapour-diffusion method. Well ordered monoclinic crystals in two different crystal forms, both with space group C2, were obtained in the presence and absence of Na(2)MoO(4) and Na(2)WO(4). Ligand-bound MopII crystallized with polyethylene glycol (PEG) 400 as a precipitant, whereas apo MopII required PEG 6000. High-resolution diffraction data were collected for ligand-bound MopII structures using synchrotron radiation to 1.8 and 1.6 A resolution for the molybdate and tungstate complexes, respectively. Data were collected on apoMopII crystals to a resolution of 1.8 A in-house.

Bacterial Proteins↗
PubMed2001

Hydrolase and sialyltransferase activities of trypanosoma cruzi trans-sialidase towards NeuAc-alpha-2,3-gal-Gal-beta-O-PNP.

NeuAc-alpha-2,3-Gal-beta-O-PNP has been synthesised and its ability to act as a substrate for the hydrolase and transferase activities of Trypanosoma cruzi trans-sialidase have been investigated. The turn-over of this compound shows marked differences from the behaviour of NeuAc-MU. In addition, distinct differences in the action of T. cruzi trans-sialidase and Clostridium perfringens neuraminidase on NeuAc-alpha-2,3-Gal-beta-O-PNP were apparent.

Clostridium perfringens↗
PubMed2001

The involvement, understanding and attitudes of dietitians towards research and audit.

AIM: To investigate the involvement of dietitians in research and audit and to assess their understanding of and attitudes towards these activities. METHODS: A postal questionnaire was used to investigate the knowledge, attitude towards and involvement in research and audit of State Registered Dietitians practising in the National Health Service (NHS) in the UK. RESULTS: A response rate of 64% was achieved. Few respondents (15%) were currently involved in research, although more (65%) were currently involved in audit. Involvement in audit rose significantly with increasing grade and managerial responsibility. Dietitians qualifying more recently were more likely to believe that their college training prepared them to undertake research, but felt less confident about undertaking audit. Experience of audit made respondents more confident about auditing their work and improved their belief that they understood audit terminology. Higher grade dietitians were more likely to see audit as an important part of their role than were their more junior colleagues. Understanding of the terms 'research' and 'audit' was poor, although 48% of respondents identified the link between the two activities. Perceived constraints to involvement in research and audit were identified. CONCLUSION: The present level of involvement of dietitians in research and audit activities falls below that recommended in the BDA's (1997a) National Professional Standards for Dietitians Practising in Healthcare. This study identifies factors that influence dietitians' involvement in, understanding of and attitudes towards research and audit and recommends ways of increasing their involvement in these activities.

Adult↗
PubMed2001

Home-style beef jerky: effect of four preparation methods on consumer acceptability and pathogen inactivation.

The safety of homemade jerky continues to be questioned. Producing a safe product that retains acceptable quality attributes is important. Lethality of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes as well as consumer acceptability and sensory attributes of jerky prepared by four methods were examined. Preparation methods were drying marinated strips at 60 degrees C (representing a traditional method), boiling strips in marinade or heating in an oven to 71 degrees C prior to drying, and heating strips in an oven after drying to 71 degrees C. A 60-member consumer panel rated overall acceptability. A 10-member descriptive panel evaluated quality attributes. Samples heated after drying and samples boiled in marinade prior to drying had slightly higher acceptability scores but were not statistically different from traditional samples. Although the four treatments were significantly different in color (P = 0.0001), saltiness (P = 0.0001), and texture (P = 0.0324), only texture appeared to influence overall consumer acceptability. Microbial challenge studies subjecting the pathogens to the four treatments showed a 5.8-, 3.9-, and 4.6-log reduction of E. coli O157:H7, L. monocytogenes, and Salmonella, respectively, even with traditional drying. Oven treatment of strips after drying was shown to have the potential to reduce pathogen populations further by approximately 2 logs. In conclusion, a safer, yet acceptable home-dried beef jerky product can be produced by oven-heating jerky strips after drying.

Animals↗
PubMed2000

Tetanus toxin fragment C expressed in live Salmonella vaccines enhances antibody responses to its fusion partner Schistosoma haematobium glutathione S-transferase.

Tetanus toxoid has been used widely as an adjuvant. The atoxic fragment C from tetanus toxin (TetC) is potently immunogenic when expressed in Salmonella vaccine strains and has been used as a fusion partner for antigens (Ag). However, there has been no formal comparison of the immunomodulatory impact of TetC on its fusion partners. In this study, we have addressed this important issue. The protective 28-kDa glutathione S-transferase (GST) from Schistosoma haematobium (Sh28GST) was expressed either as a fusion to TetC or as the full-length Sh28GST alone in a nonvirulent aroA-attenuated strain of Salmonella enterica serovar Typhimurium. The Sh28GST proteins were soluble and stably expressed in Salmonella, as evaluated by Western blotting with TetC and/or Sh28GST antisera. Mice were immunized orally with a single dose of the live recombinant Salmonella. The constructs were stable in mice but, dramatically, only the strain expressing the TetC-Sh28GST fusion elicited significant antibody (Ab) responses directed against Sh28GST as determined by enzyme-linked immunosorbent assay. An analysis of the isotype profiles showed that these mice also produced anti-Sh28GST immunoglobulin A and GST-neutralizing assays revealed high levels of neutralizing Abs in sera. These are important correlates of protection in schistosomiasis. In addition, stimulation of spleen cells from immunized mice with Sh28GST Ag showed that both strains, expressing Sh28GST alone or the TetC-Sh28GST fusion, were able to stimulate the secretion of Th1-related cytokines (gamma interferon and interleukin 2) to comparable levels. Thus, TetC has modulated the immune responses generated against its fusion partner, Sh28GST, by markedly enhancing the Ab responses elicited. These results have important implications in the rational development of live vaccines.

Adjuvants, Immunologic↗
PubMed1999

The role of the C-terminal domain in the inhibitory functions of tissue factor pathway inhibitor.

Tissue factor pathway inhibitor (TFPI) inhibits the activity of coagulation factors VIIa and Xa through Kunitz domains, thereby inhibiting the activity of tissue factor. However, it has been shown that the C-terminal of this inhibitor is essential for the maximal anticoagulant activity of TFPI. We have investigated the endogenous ability of the C-terminal of TFPI to influence coagulation. A synthetic peptide corresponding to residues 254-265 within the C-terminal of TFPI was prepared and shown to be capable of inhibiting tissue factor pathway by preventing the activation of factor VII. Mutational analysis of the peptide revealed the identity of the key lysine residues.

Amino Acid Sequence↗
PubMed1999

Interleukin 18 contributes to host resistance and gamma interferon production in mice infected with virulent Salmonella typhimurium.

Spleen and peritoneal macrophages obtained from innately resistant A/J mice released low levels of interleukin 18 (IL-18) upon infection with Salmonella typhimurium C5 RP4. Incubating the cells with recombinant gamma interferon (rIFN-gamma) enhanced IL-18 production. A/J mice treated in vivo with anti-IL-18 antibodies showed impaired resistance to infection, with increased bacterial loads in the liver and spleen. Administration of rIL-18 could protect A/J mice from challenge with a lethal dose of virulent salmonellae, with a dramatic reduction in bacterial numbers in the tissues. rIL-18 administration did not ameliorate the disease in IFN-gamma-R-/- mice. IL-18 proved to be required for IFN-gamma production by mouse splenocytes from conventional, scid, and rag-1(-/-) mice; in vivo IL-18 neutralization caused a decrease in circulating IFN-gamma levels. Thus, IL-18 is a key factor in early host resistance to Salmonella and probably acts via IFN-gamma.

Animals↗
PubMed1998

Single photon infrared emission spectroscopy: a study of IR emission from UV laser excited PAHs between 3 and 15 micrometers.

Single-photon infrared emission spectroscopy (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs). A supersonic free-jet expansion has been used to provide emission spectra of rotationally cold and vibrationally excited naphthalene and benzene. Under these conditions, the observed width of the 3.3-micrometers (C-H stretch) band resembles the bandwidths observed in experiments in which emission is observed from naphthalene with higher rotational energy. To obtain complete coverage of IR wavelengths relevant to the unidentified infrared bands (UIRs), UV laser-induced desorption was used to generate gas-phase highly excited PAHs. Lorentzian band shapes were convoluted with the monochromator-slit function in order to determine the widths of PAH emission bands under astrophysically relevant conditions. Bandwidths were also extracted from bands consisting of multiple normal modes blended together. These parameters are grouped according to the functional groups mostly involved in the vibration, and mean bandwidths are obtained. These bandwidths are larger than the widths of the corresponding UIR bands. However, when the comparison is limited to the largest PAHs studied, the bandwidths are slightly smaller than the corresponding UIR bands. These parameters can be used to model emission spectra from PAH cations and cations of larger PAHs, which are better candidate carriers of the UIRs.

Argon↗
PubMed1998

Interleukin-12 is required for control of the growth of attenuated aromatic-compound-dependent salmonellae in BALB/c mice: role of gamma interferon and macrophage activation.

The attenuated S. typhimurium SL3261 (aroA) strain causes mild infections in BALB/c mice. We were able to exacerbate the disease by administering anti-interleukin-12 (IL-12) antibodies, resulting in bacterial counts in the spleens and livers of anti-IL-12-treated mice that were 10- to 100-fold higher than the ones normally observed in premortem mice; yet the animals showed only mild signs of illness. Nevertheless, they eventually died of a slow, progressive disease. Mice infected with salmonellae become hypersusceptible to endotoxin. We found that IL-12 neutralization prevented the death of infected mice following subcutaneous injection of lipopolysaccharide. Granulomatous lesions developed in the spleens and livers of control animals, as opposed to a widespread infiltration of mononuclear cells seen in the organs of anti-IL-12-treated mice. In the latter (heavily infected), salmonellae were seen within mononuclear cells, indicating an impairment of the bactericidal or bacteriostatic ability of the phagocytes in the absence of biologically active IL-12. Gamma interferon (IFN-gamma) levels were reduced in the sera and tissue homogenates from anti-IL-12-treated mice compared to those in control animals. Furthermore, fluorescence-activated cell sorter analysis on spleen cells showed that IL-12 neutralization impaired the upregulation of I-Ad/I-Ed antigens on macrophages from infected mice. Inducible nitric oxide synthase and IFN-gamma mRNA production was down-regulated in anti-IL-12-treated mice, which also showed an increased production of IL-10 mRNA and a decrease in nitric oxide synthase activity in the tissues. Administration of recombinant IFN-gamma to anti-IL-12-treated mice was able to restore host resistance, granuloma formation, and expression of major histocompatibility complex class II antigens in F4/80(+) and CD11b+ spleen cells.

Animals↗
PubMed1998

Survival of Escherichia coli O157:H7 in ground beef jerky assessed on two plating media.

Recent outbreaks of food-borne illness due to Salmonella spp. in beef jerky and Escherichia coli O157:H7 in venison jerky, coupled with the fact that a variety of preparation methods and dying procedures abound, raise concern over the safety of processed meat products made in the home. The potential of injured bacterial cells to regain the ability to cause illness is a particular threat with pathogens such as E. coli O157:H7, which is believed to have a low infectious dose. This study examined the efficacy of various methods of jerky preparation in reducing populations of E, coli O157:H7 in ground beef jerky and compared the recovery rate of E. coli O157:H7 on two selective plating media, modified sorbitol MacConkey agar (MSMA) and modified eosin methylene blue agar (MEMB). Populations of E. coli O157:H7 in both heated and unheated samples exhibited a greater decline during drying when a nitrite and salt cure mix was added during jerky preparation. When recovery of E. coli O157:H7 on MSMA and MEMB was compared, a trend toward slightly higher recovery rates with MEMB was observed. On the basis of these results, MEMB is a suitable alternative to MSMA for the recovery of E. coli O157:H7 from heated and dried meat samples similar to beef jerky.

Animals↗
PubMed1997

Correlates of protection induced by live Aro- Salmonella typhimurium vaccines in the murine typhoid model.

Live attenuated salmonella vaccines generally confer better protection than killed vaccines. The immune responses in BALB/c mice elicited by immunization with a live attenuated Aro Salmonella typhimurium vaccine given orally, intravenously or subcutaneously were compared with those elicited by killed whole-cell vaccines (acetone or heat-treated) given subcutaneously. Live vaccines given by all routes elicited higher interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) responses in spleen cells against an alkali-treated whole-cell salmonella lysate than did killed vaccines. Live and killed vaccines elicited high total antibody levels to smooth lipopolysaccharide (LPS) (enzyme-linked immunosorbent assay), but all live vaccine regimes elicited higher IgG2a, suggesting a Th1 response. Oral and intravenous vaccination with live organisms elicited IgA against smooth LPS which subcutaneous vaccination with live or killed salmonellae failed to evoke. Western blots using rough whole-cell lysates showed that all vaccines elicited a varied anti-protein response; however, all groups immunized with live organisms recognized three unidentified bands of MW 52,000, 46,000 and 18,000 which were consistently absent in groups immunized with killed organisms. The results indicate that immunization with live aroA salmonellae elicited a Th1 type of response, including bystander T-cell help to LPS, and a response to proteins not seen in mice that received killed vaccines.

Administration, Oral↗
PubMed1997

Expression and immunogenicity of an Echinococcus granulosus fatty acid-binding protein in live attenuated Salmonella vaccine strains.

Fatty acid-binding proteins (FABPs) are candidate molecules for vaccines against several parasitic platyhelminths. A FABP from the cestode Echinococcus granulosus (EgDf1) was expressed in Salmonella vaccine strains as a C-terminal fusion to fragment C of tetanus toxin (TetC) by using expression vector pTECH. The fusion protein was equally expressed in several attenuated vaccine strains derived from bacteria with different genetic backgrounds and different attenuating mutations. Single-dose immunization experiments with the aroA Salmonella typhimurium strain SL3261 carrying the pTECH-EgDf1 construct were conducted with mice, using both the intravenous and the oral routes. Surprisingly, the antibody response to EgDf1 and the antigen-specific cytokine production in spleen cells were stronger in mice immunized orally. Furthermore, immune mouse sera strongly reacted with fixed sections of the worm's larval stage. Analysis of the isotype distribution of the specific anti-EgDf1 antibodies showed similar production of immunoglobulin G1 (IgG1) and IgG2a together with specific IgA antibodies. In addition, stimulation of spleen cells from mice immunized with the different constructs with either Salmonella lysate, TetC, or EgDf1 showed that, together with Th1-related cytokines (gamma interferon and interleukin 2 [IL-2]), significant levels of a Th2 cytokine (IL-5) were produced specifically, indicating a Th2 component to the response to the Salmonella carrier and to the recombinant antigens. Salmonellae expressing the TetC-rEgDfl fusion are currently under evaluation as potential vaccines against E. granulosus.

Animals↗
PubMed1996

Down-regulation of hormone-sensitive lipase in sterol ester-laden J774.2 macrophages.

The development of atherosclerotic plaques in arteries is a key step in atherogenesis, with cholesterol ester accumulation in macrophage-derived foam cells being recognized as a major pathogenic event in this process. In this study, the mouse macrophage cell line J774.2 was induced to accumulate intracellular sterol esters by incubation with 25-hydroxycholesterol in the presence of oleic acid. The accumulation of sterol esters in these cells was found to be accompanied by a marked decrease in the activity of the enzyme responsible for their hydrolysis, namely hormone-sensitive lipase (HSL); Western blotting studies revealed a corresponding decrease in the levels of the HSL polypeptide. Similar findings were obtained after incubation with oxidized low-density lipoprotein or very-low-density lipoprotein. These findings suggest that down-regulation of the expression of HSL is important in cholesterol ester accumulation in macrophages.

Animals↗
PubMed1996

Protection against oral challenge three months after i.v. immunization of BALB/c mice with live Aro Salmonella typhimurium and Salmonella enteritidis vaccines is serotype (species)-dependent and only partially determined by the main LPS O antigen.

The role of the main LPS O antigen in the specificity of protection as mediated by systemic mechanisms following immunization with live attenuated Aro Salmonella vaccines was studied in mice. Innately Salmonella-susceptible (Itys) BALB/c mice were immunized intravenously with a single dose of either Salmonella typhimurium SL3261 aroA (LPS O4,5,12) or Salmonella enteritidis Se795aroA (LPS O1,9,12), and challenged orally 2-3 months later with either S. typhimurium C5 or S. enteritidis Thirsk. Nearly isogenic transductants of the two challenge strains expressing either their own LPS or that of the other serotype (S. typhimurium C5 O4 or O9, and S. enteritidis Thirsk O9 or O4) were also used. Both vaccines conferred similar high protection against the virulent strain of the homologous serotype expressing its own LPS. There was no protection against the heterologous serotype expressing its own LPS. However, when vaccinated mice were challenged with either the same serotype as the vaccine but expressing the heterologous LPS, or with the heterologous serotype expressing the LPS of the vaccine, protection was always lower than protection against the fully homologous serotype. Anti-smooth LPS antibodies showed higher titres against the homologous LPS, but with significant crossreactivity with the heterologous LPS. Antibodies to O-rough S. typhimurium and S. enteritidis LPS were present following immunization with either of the two vaccine strains. The LPS alone cannot fully account for the specificity of protection in this model; other (protein) antigens may be responsible. It remains to be seen whether there is a T-cell mediated component to the specificity of protection conferred by live Salmonella vaccines.

Animals↗
PubMed1996

Prosthodontic management of a combination transosteal/endosteal implant reconstruction: a clinical report.

This is a clinical report of a patient who was not referred for prosthodontic evaluation and treatment until after undergoing Bränemark endosseous implant placement to supplement the previously existing mandibular staple bone plate implant. This supplemental treatment was the surgeon's attempt to resolve the patient's complaint of loose dentures. Creativity with implant biomechanics and prosthodontic design were necessary to restore the patient, in a predictable manner, to normal function. A fixed, detachable cast overdenture bar rigidly connected to all the implants was constructed utilizing resilient attachments to retain the tissue-supported mandibular overdenture. A presurgical prosthodontic evaluation could have averted many of the problems encountered with treatment. More effective conventional prosthodontic treatment may have resolved the patient's complaints and eliminated the need for additional implant placement.

Bone Plates↗