Biomedical subjects

S J Harris

Publications and source records attributed to S J Harris.

At least 37 records · Page 2Linked to original sources

PubMed1999

Protection against Helicobacter pylori infection by intestinal immunisation with a 50/52-kDa subunit protein.

A mouse model of Helicobacter pylori infection was used to evaluate the vaccine antigen potential of the citrate synthase homologue protein purified from the H. pylori NCTC 11637 strain. Mice were immunised with the protein by intra-Peyer's patch immunisation. This route gives maximal intestinal immunisation and was used to screen oral vaccine candidate antigens without the added complication of simultaneously testing oral delivery systems. Two weeks post-immunisation mice were infected with Sydney strain H. pylori and 4 weeks after infection the mice were killed and the level of H. pylori infection in the stomach determined. Pre-immunisation with the 50/52-kDa protein led to a 84-91% reduction in H. pylori infection compared to unimmunised controls.

Animals↗

PubMed1998

Identification and characterization of kraken, a gene encoding a putative hydrolytic enzyme in Drosophila melanogaster.

Kraken, a novel Drosophila gene isolated from a 4-8-h-old Drosophila embryo cDNA library, shows homology to a family of serine hydrolases whose common feature is that they all catalyse breakage of substrates with a carbonyl-containing group. It is a single-copy gene with at least two introns and maps to position 21D on polytene chromosomes. kraken is a member of a conserved gene family. Messenger RNA of kraken is expressed ubiquitously in early embryogenesis. Later, it is concentrated in the foregut and the posterior midgut primordium. Towards the end of embryogenesis, expression of kraken is confined to the gastric caeca. During the third-instar larval stage, kraken is expressed at low levels in the gastric caeca and parts of the gut, and at higher levels in the fat body. We suggest a role for Kraken in detoxification and digestion during embryogenesis and larval development.

Amino Acid Sequence↗

PubMed1998

Binding of purified 14-3-3 zeta signaling protein to discrete amino acid sequences within the cytoplasmic domain of the platelet membrane glycoprotein Ib-IX-V complex.

The glycoprotein (GP) Ib-IX-V complex constitutively expressed on the platelet plasma membrane mediates initial adhesion of circulating platelets to vessel wall matrix at high shear, and shear-induced platelet aggregation. In both cases, this involves binding of GP Ib-IX-V to the adhesive glycoprotein, von Willebrand Factor (vWF). vWF binding to GP Ib-IX-V rapidly induces platelet activation, leading to cytoskeletal rearrangement, shape change, and secretion that enables alphaIIbbeta3 integrin (GP IIb-IIIa)-dependent platelet aggregation. All these events are critical in (patho)physiological thrombus formation. The recent discovery that the signaling protein, 14-3-3 zeta, copurifies with the GP Ib-IX complex (minus GP V) [Du, X., Harris, S. J., Tetaz, T. J., Ginsberg, M. H., & Berndt, M. C. (1994) J. Biol. Chem. 269, 18287-18290] indicated a potential mechanism for vWF-dependent signaling. The aim of the present study was to identify discrete amino acid sequences that bind 14-3-3 zeta within the cytoplasmic domain of the receptor. As an initial screening assay, overlapping synthetic peptides based on the cytoplasmic domains of GP Ibalpha (100 residues), GP Ibbeta (34 residues), GP IX (5 residues), and GP V (16 residues) were immobilized and assessed for the ability to bind purified 14-3-3 zeta. The C-terminal sequence GHSL of GP Ibalpha was identified as one 14-3-3 zeta interactive sequence, consistent with previous results [Du, X., Fox, J. E., & Pei, S. (1996) J. Biol. Chem. 271, 7362-7367]. Binding of 125I-labeled 14-3-3 zeta to GHSL-containing peptides was inhibitable by unlabeled 14-3-3 zeta and by anti-14-3-3 zeta IgG. Ala-walking through the GHSL sequence suggested all residues were necessary for optimal binding. In addition, 14-3-3 zeta bound with lower affinity to a peptide based on the central region of the GP Ibalpha cytoplasmic domain (Arg-557-Gly-575), whereas peptide sequences within the cytoplasmic domains of GP Ibbeta (Arg-160-Arg-175) and GP V (Lys-529-Gly-544) bound 14-3-3 zeta with comparable affinity to the GHSL-containing peptide. Soluble GHSL-containing peptides, GP Ibbeta- and GP V-based peptides semidissociated 14-3-3 zeta from GP Ib-IX-V or GP Ib-IX in platelet extracts as analyzed by immunoprecipitation, suggesting these sequences, at least partially, mediate the GP Ib-IX-V-14-3-3 zeta interaction in cells. Further, phosphorylation of the GP Ibbeta peptide at a site corresponding to a protein kinase A phosphorylation site (Ser-166) enhanced the affinity of 14-3-3 zeta binding by approximately 8-fold, suggesting phosphorylation as a potential mechanism for regulating 14-3-3 zeta association with the GP Ib-IX-V complex.

14-3-3 Proteins↗

PubMed1998

An audit and evaluation of bladder movements during radical radiotherapy.

With the introduction of the conformal approach for radical radiotherapy for prostate cancer, there has been renewed interest in the movement of the prostate and other pelvic organs during the course of radical pelvic radiotherapy. Many patients reviewed during a course of radical radiotherapy for bladder carcinoma have urinary flow symptoms, which may suggest impaired bladder emptying. There is concern, therefore, that the bladder volume may increase during such treatment, leading to inadequate coverage of the bladder by the planning target volume. We used serial CT scans to assess bladder size in 20 patients during the course of radical bladder radiotherapy. Our results showed that there was little variation in the left to right direction and, in 12 of the 20 patients studied, the anteriorposterior (AP) movement was < 1 cm. The bladder dome rose out of the treatment field in two patients during the course of therapy. However, in 16 patients, the target volume was encompassed as planned throughout.

Humans↗

PubMed1998

The hexA gene of Erwinia carotovora encodes a LysR homologue and regulates motility and the expression of multiple virulence determinants.

We have identified a gene important for the regulation of exoenzyme virulence factor synthesis in the plant pathogen Erwinia carotovora ssp. carotovora (Ecc) and virulence and motility in Erwinia carotovora ssp. atroseptica (Eca). This gene, hexA (hyperproduction of exoenzymes), is a close relative of the Erwinia chrysanthemi (Echr) gene pecT and encodes a member of the LysR family of transcriptional regulators. hexA mutants in both Ecc and Eca produce abnormally high levels of the exoenzyme virulence factors pectate lyase, cellulase and protease. In addition, Eca hexA mutants show increased expression of the fliA and fliC genes and hypermotility. Consistent with a role as a global regulator, expression of hexA from even a low-copy plasmid can suppress exoenzyme production in Ecc and Eca and motility in Eca. Production of the quorum-sensing pheromone OHHL in Ecc hexA is higher throughout the growth curve compared with the wild-type strain. Overexpression of Ecc hexA also caused widespread effects in several strains of the opportunistic human pathogen, Serratia. Low-copy hexA expression resulted in repression of exoenzyme, pigment and antibiotic production and repression of the spreading phenotype. Finally, mutations in hexA were shown to increase Ecc or Eca virulence in planta.

4-Butyrolactone↗

PubMed1997

CD36 forms covalently associated dimers and multimers in platelets and transfected COS-7 cells.

CD36 is a transmembrane glycoprotein expressed on the surface of a number of cell types. The analysis of CD36 from platelets using immunoblotting, gel filtration, and native PAGE indicated the presence of high molecular complexes exceeding the Mr of monomeric CD36. Experiments using transfected COS-7 cells revealed these complexes were homodimers and -multimers of CD36. The multimers could be dissociated by treatment with a reducing agent, indicating they were formed by intermolecular cysteine-bridging. Mutagenesis of the cDNA for CD36 implicated the cysteines in the extracellular domain of the molecule. The potential physiological roles of CD36 multimerisation are discussed.

Animals↗

PubMed1997

A protein particle vaccine containing multiple malaria epitopes.

Ty virus-like particles consist of a single protein species that can be produced in yeast. Recombinant Ty-VLPs carrying a string of up to 15 defined cytotoxic T lymphocyte (CTL) epitopes from Plasmodium species prime protective CTL responses in mice following a single administration without adjuvant. Effective processing of epitopes from the string was demonstrated in vitro and in vivo and was not affected by flanking sequences.

Amino Acid Sequence↗

PubMed1997

Prediction of murine MHC class I epitopes in a major house dust mite allergen and induction of T1-type CD8+ T cell responses.

The group I (Der p 1) allergen of Dermatophagoides pteronyssinus (house dust mite, HDM) contains several T helper (Th) epitopes recognized by C57BL/6 mice, with the peptide (111-139) containing a dominant MHC class II-restricted epitope (113-127). Since CD8+ T cells are thought to play a role in the regulation of allergic disease, we examined the Der p 1 sequence for potential MHC class I-binding motifs and observed that residues 111-119 (FGISNYCQI) contain motifs for H-2Db and Kb. Furthermore, immunization of C57BL/6 mice with unadjuvanted Ty virus-like particles (VLP) carrying Der p 1 (111-139), a method known to induce murine cytotoxic T lymphocyte (CTL) responses, primed Der p 1 (111-119)-specific Db-restricted CTL which produce high levels of IFN-gamma and low levels of IL-5 and IL-6 in vitro (T1-type CTL). VLP carrying the minimal epitope (FGISNYCQI) also induced a CTL response following immunization without adjuvant by various routes. Der p 1 (111-139)-VLP adjuvanted with alum did not prime CTL in C57BL/6 mice but were found to prime Th1-type CD4+ T cells that recognize the overlapping peptide (113-127) and native protein. The ability to successfully predict allergen-specific CD8+ T cell epitopes and prime CD8+ and/or CD4+ T cell responses provides an opportunity to dissect the relative roles of these T cells in the regulation of allergic responses and may offer therapeutic potential for reprogramming Th2-type allergic responses.

Administration, Intranasal↗

PubMed1997

Active compliance in robotic surgery--the use of force control as a dynamic constraint.

Robotic surgery can be carried out automatically by using a robot to move the cutting tool under position control. However, although the surgeon can observe the procedure on a visual display and has the ability to stop the operation in an emergency, he has little direct contact with the task. An alternative approach is to involve the surgeon more directly, by his moving a robot using active force control. The robot is then used to allow motion in preprogrammed regions, by the surgeon back-driving the robot motors, while preventing motion in prohibited areas. This active constraint robot (or ACROBOT) is described in this paper applied to knee surgery, in which the knee bones are accurately machined to allow the fitting of prosthetic knee implants. The ACROBOT is, however, ideally suited to a range of surgical procedure, because it allows the surgeon to feel the forces exerted during cutting and take appropriate action. This ability to be in direct control, while being constrained to cut within a permitted region, enhances safety and makes the system more acceptable to the medical community. The system of programmable constraint also allows the ACROBOT to provide the traditional benefits of robot surgery, namely the ability to machine complex geometrical surfaces very accurately and to make repetitive motions tirelessly. The system also has a potential for minimally invasive procedures. In knee surgery, for example, the robot could operate through a small incision in the skin and excise a volume into which a small, specially designed, unicompartmental prosthesis could fit.

Arthroplasty, Replacement, Knee↗

PubMed1997

The Probot--an active robot for prostate resection.

As men age, their prostates can enlarge, causing urinary difficulty. Surgery to correct this [transurethral resection of the prostate (TURP)] is a skilled and time-consuming operation requiring many repetitive motions of a cutter. A robot has been developed to perform these motions, relieving the surgeon of much of the burden of surgery. This robot has been tried both in the laboratory and later on human subjects and has proved itself capable of performing prostate resection. The Probot system consists of on-line imaging and three-dimensional prostate model construction, an appropriate surgeon-computer interface, a counterbalanced mounting frame and a computer controlled robot.

Computer Graphics↗

PubMed1996

Dendritic cells process exogenous viral proteins and virus-like particles for class I presentation to CD8+ cytotoxic T lymphocytes.

Previous reports have indicated that both dendritic cells and macrophages have the ability to induce cytotoxic T lymphocyte (CTL) and T helper (Th) cell responses in vivo. Dendritic cells process exogenous antigens conventionally for presentation on major histocompatibility complex (MHC) class II molecules. However, unconventional processing of exogenous antigens in vitro for presentation on MHC class I molecules is still an open question. In this study, we report that a cloned dendritic cell line (D2SC/1) is able to present cell debris-associated exogenous viral proteins to MHC class I-restricted CTL in vitro. The dendritic cell line was very efficient in processing recombinant lymphocytic choriomeningitis virus nucleoprotein (LCMV NP) and presenting the class I-restricted epitope to CTL primed in vivo. Peritoneal macrophages could also process the recombinant LCMV NP for subsequent MHC class I presentation, but were less efficient compared to the dendritic cells. Furthermore, recombinant yeast-derived virus-like particles carrying the HIV-1 V3 loop (V3-VLP), which are protenaceous and do not contain any lipid, were also found to be efficiently processed by the dendritic cell line for presentation of the class I-restricted epitope. These results clearly indicate that viral proteins, in particulate form or associated with cell debris, are processed by dendritic cells for CTL induction.

Amino Acid Sequence↗

PubMed1996

Dopamine directly activates a ligand-gated channel in snail neurones.

Synaptically released dopamine is known to evoke fast as well as slow synaptic potentials in neurones of gastropod molluscs. Here evidence is presented that the fast excitatory response to dopamine is mediated by the direct activation of a ligand-gated channel: unitary currents were observed in outside-out patches of neurones exposed to dopamine, and the response persisted in the presence of intracellular guanosine 5'-o-(2-thiobiphosphate), GDP[beta-S], a condition known to block G-protein-coupled responses to dopamine and other agents. In whole-cell recordings, the fast response desensitized very rapidly; it was less desensitized in outside-out patches, suggesting dependence of desensitization on an intracellular factor. The response to dopamine was blocked by D-tubocurarine and strychnine (both probably by channel blockade), by apomorphine, chlorpromazine and relatively high doses of (+/-)-sulpiride and spiperone. The channel conducts predominantly monovalent cations. Unexpectedly, the fast response to dopamine was also observed in an identified dopaminergic neurone when maintained in isolation in culture. The receptors on the dopaminergic neurone were unevenly distributed, being more abundant on the axon-hillock, axon and neurite terminals.

Animals↗

PubMed1996

The effects of adjuvants on CTL induction by V3:Ty-virus-like particles (V3-VLPs) in mice.

We have previously described the generation of HIV-1 V3-specific cytotoxic T-lymphocytes (CTL) responses in BALB/c (H-2d) mice following immunization with Ty-virus-like particles carrying the V3 loop of gp120 (V3-VLPs) without adjuvant. In this study the effects of various adjuvants on CTL induction by V3-VLPs was examined. Mice immunized with V3-VLPs formulated in aqueous-based adjuvants, Detox, gamma-inulin, galactosaminylmuramyl dipeptide and Chemivax generated V3-specific CTL responses, although at reduced levels when compared to the no adjuvant group. V3-VLPs prepared in Alhydrogel, algamulin or as an oil emulsion in SAF-MF failed to generate V3-specific CTL responses. The mechanism whereby alum prevented the induction of a CTL response was investigated further. Immunization with V3-VLPs prepared in non-saturating doses of alum or alum plus EDTA primed for strong CTL responses, indicating that free VLPs do, but alum-bound VLPs do not enter the MHC class I processing pathway of antigen-presenting cells (APCs). Furthermore, V3-VLPs with very low doses of alum led to an enhancement of the CTL response. The formulation of hybrid Ty-VLPs in oil based or precipitating adjuvants, therefore, inhibits access to the MHC class I processing pathway of APCs. The intact particulate structure of hybrid VLPs is therefore strictly necessary for CTL induction.

Adjuvants, Immunologic↗

PubMed1996

Bidirectional interaction of valproate and lamotrigine in healthy subjects.

OBJECTIVE: To evaluate the steady-state pharmacokinetics of lamotrigine and valproate at three dosing levels of lamotrigine in normal volunteers receiving steady-state therapeutic doses of valproate. METHODS: This was an open-label, randomized, three-way crossover study of 18 normal male volunteers. Subjects received oral valproate (500 mg Depakote twice a day) throughout the study. Each subject subsequently received three oral dosage regimens of lamotrigine (50, 100, or 150 mg/day) for 1 week each, with a 2-week washout period between lamotrigine treatment periods. Valproate and lamotrigine trough plasma samples were determined by a capillary gas chromatography method and immunofluorometric assay, respectively. Urine samples were assayed for 11 valproate metabolites by gas chromatography/mass spectrometry. RESULTS: When compared to other studies in which lamotrigine was administered with no concurrent antiepileptic drug, concomitant valproate markedly increased the half-life of lamotrigine and decreased lamotrigine clearance, without substantial alteration in the linear kinetics of the drug. The addition of lamotrigine was associated with a small but significant 25% decrease in steady-state valproate plasma concentration. Oral clearance of valproate was increased (from 7.2 +/- 1.1 ml/hr/kg before lamotrigine treatment to 9.0 +/- 2.0 ml/hr/kg on day 28; p < 0.05). The formation clearance of the hepatotoxic valproate metabolites, 2-n-propyl-4-pentenoic acid (4-ene-valproate) and 2-propyl-2,4-pentadienoic acid [2(E),4-diene-valproate], was unaffected by lamotrigine administration. CONCLUSIONS: As a consequence of the interaction between lamotrigine and sodium valproate, a dosage reduction of lamotrigine should be considered in patients taking a combination of valproate and lamotrigine.

Analysis of Variance↗

PubMed1996

Irradiation of the scrotum: what some men need MOST: the Manual Orchid Shielding Technique.

Although the need for radiotherapy to the scrotum is now unusual, shielding for the contralateral testis is used to maintain fertility and to preserve the endocrine function of the testis. We report a simple radiotherapy technique to achieve this by manually removing the contralateral testis proximally from the scrotum, to the level of the inguinal ring, where it is held by the patient during radiotherapy. A lead shield placed over the hand, testis and penis reduces the dose to the testis to an acceptable < 1.5% of the tumour dose. This can be confirmed by thermoluminescent dosimetry.

Humans↗

PubMed1996

Pulmonary metastases, an occult prostatic adenocarcinoma and delayed administration of antiandrogens.

The presentation of prostatic carcinoma with pulmonary metastases is unusual. The patient reported here presented with nodular lung metastases from an unknown primary site and 3.5 years later became symptomatic with a prostatic carcinoma. Subsequent hormonal therapy led to radiological regression of the pulmonary metastases. This case report demonstrates the progression of asymptomatic prostatic lung metastases with time and their response to delayed hormonal therapy, which is discussed.

Adenocarcinoma↗

PubMed1996

Induction of single and dual cytotoxic T-lymphocyte responses to viral proteins in mice using recombinant hybrid Ty-virus-like particles.

The induction of cytotoxic T-lymphocyte (CTL) responses to viral proteins is thought to be an essential component of protective immunity against viral infections. Methods for generating such responses in a reproducible manner would be of great value in vaccine development. We demonstrate here that the recombinant antigen-presentation system based on the yeast transposon (Ty) particle-forming p1 protein is a potent means of inducing CTL responses to a variety of viral CTL epitopes, including influenza virus nucleoprotein (two epitopes), Sendai virus and vesicular stomatitis virus nucleoproteins, and the V3 loop of human immunodeficiency virus type-1 (HIV-1) gp120. CTL were primed by hybrid Ty-virus-like particles (VLP) carrying the minimal epitope or as much as 19,000 MW of protein. Ty-VLP carrying two different epitopes (dual-epitope Ty-VLP) were capable of priming CTL responses in two different strains of mice or against two epitopes in the same individual. Furthermore, co-administration of a mixture of two different Ty-VLP carrying single epitopes could induce responses to both epitopes in the same individual. Ty-VLP appear to represent a reproducible and flexible system for inducing CTL responses in mice, and warrant further evaluation in primates.

Amino Acid Sequence↗

PubMed1996

Confession-building, long-distance networks, and the organization of Jesuit science.

The ability of the Society of Jesus to engage in a broad and enduring tradition of scientific activity is here addressed in terms of its programmatic commitment to the consolidation and extension of the Catholic confession (i.e., to a multipronged program of confession-building) and its mastery of the administrative apparatus necessary to operate long-distance networks. The Society's early move into two major apostolates, one in education and the other in the overseas missions, brought Jesuits into regular contact with the educated elites of Europe and at the same time placed the society's missionaries in remote parts of the natural world. The modes of organization of travel and communication required by the Society's long-distance networks (i.e., the training and deployment of reliable agents willing to work under direction in remote locations and capable of providing trustworthy reports and observations to their superiors through regular exchange of correspondence) not only facilitated scientific communication and collaboration within the order, it also provided Jesuits with the resources they needed to engage successfully in 'ministries among the learned'. Evidence of a sustained attempt by Jesuit authors to assume the role of Kulturträger is found in the several genres of scientific publications that dominate the society's scientific corpus. Thus the society's early recognition of the "apostolic value" of scientific publications in recruiting friends and allies among Europe's intellectual elites, I argue, allowed a robust interest in natural knowledge to emerge as a legitimate part of the Jesuit vocation.

Catholicism↗