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Biomedical subjects

P Shaw

Publications and source records attributed to P Shaw.

At least 55 records · Page 3Linked to original sources
PubMed2001

Scavenger receptors, oxidized LDL, and atherosclerosis.

Oxidized LDL (OxLDL) competes with oxidatively damaged and apoptotic cells for binding to mouse peritoneal macrophages, implying the presence of one or more common domains. However, the nature of the ligands involved has not been determined. Studies in this laboratory over the last several years provide evidence that oxidized phospholipids, present in OxLDL and also in the membrane of apoptotic cells, represent one such ligand. These oxidized phospholipids, either in the lipid phase of OxLDL or becoming attached covalently to apoprotein B during LDL oxidation, have been shown to play a major role in the binding of OxLDL to CD36 and to SR-B1 expressed in transfected cells. The lipid and protein moieties compete with each other to some extent, indicating that they are binding to at least one common site. A monoclonal antibody selected because of its reactivity with OxLDL proved to be an antibody against oxidized phospholipids (but not native phospholipids). This antibody (EO6) blocked the uptake of OxLDL by CD36 and by SR-B1 in transfected cells by as much as 80%; it also inhibited macrophage phagocytosis of apoptotic cells by about 40%. Thus, the persistence of receptors for OxLDL during evolution is probably accounted for by their role in recognition of ligands on the surfaces of oxidatively damaged or apoptotic cells. This has important implications in biology generally and specifically in atherogenesis, because apoptosis is a prominent feature of late lesions.

Animals↗
PubMed2001

Subacute pulmonary granulomatous schistosomiasis: high resolution CT appearances--another cause of the halo sign.

A case of probable acute granulomatous pulmonary schistosomiasis is described with multiple focal opacities on chest radiography and widespread, but predominantly peribronchovascular, nodules with ground-glass halos on high resolution CT (HRCT). The HRCT appearances in early schistosomiasis have not been described previously. Although the features are not diagnostic and may be seen in other conditions, in the appropriate clinical context they may suggest pulmonary involvement in schistosomiasis. The features of pulmonary schistosomiasis in the different stages of infection are discussed. Pulmonary involvement should be suspected in patients with even minor respiratory symptoms when there is a history of exposure to fresh water in endemic areas.

Acute Disease↗
PubMed2001

Involvement of connexin 43 in meiotic maturation of bovine oocytes.

In ovarian follicles, cumulus cells provide the oocyte with small molecules that permit growth and control maturation. These nutrients reach the germinal cell through gap junction channels, which are present between the cumulus cells and the oocyte, and between the cumulus cells. In this study the involvement of intercellular communication mediated by gap junction channels on oocyte maturation of in vitro cultured bovine cumulus-oocyte complexes (COCs) was investigated. The stages of oocyte maturation were determined by Hoechst 33342 staining, which showed that 90% of COCs placed in the maturation medium for 24 h progress to the metaphase II stage. Bovine COC gap junction communication was disrupted initially using n-alkanols, which inhibit any passage through gap junctions. In the presence of 1-heptanol (3 mmol l(-1)) or octanol (3.0 mmol l(-1) and 0.3 mmol l(-1)), only 29% of the COCs reached metaphase II. Removal of the uncoupling agent was associated with restoration of oocyte maturation, indicating that treatment with n-alkanols was neither cytotoxic nor irreversible. Concentrations of connexin 43 (Cx43), the major gap junction protein expressed in the COCs, were decreased specifically using a recombinant adenovirus expressing the antisense Cx43 cDNA (Ad-asCx43). The efficacy of adenoviral infection was > 95% in cumulus cells evaluated after infection with recombinant adenoviruses expressing the green fluorescence protein. RT-PCR performed on total RNA isolated from Ad-asCx43-infected COCs showed that the rat Cx43 cDNA was transcribed. Western blot analysis revealed a three-fold decrease in Cx43 expression in COCs expressing the antisense RNA for Cx43. Injection of cumulus cells with Lucifer yellow demonstrated further that the resulting lower amount of Cx43 in infected COCs is associated with a two-fold decrease in the extent of coupling between cumulus cells. In addition, oocyte maturation was decreased by 50% in the infected COC cultures. These results indicate that Cx43-mediated communication between cumulus cells plays a crucial role in maturation of bovine oocytes.

Adenoviridae↗
PubMed2001

Native and artificial reticuloplasmins co-accumulate in distinct domains of the endoplasmic reticulum and in post-endoplasmic reticulum compartments.

We compared the subcellular distribution of native and artificial reticuloplasmins in endosperm, callus, and leaf tissues of transgenic rice (Oryza sativa) to determine the distribution of these proteins among endoplasmic reticulum (ER) and post-ER compartments. The native reticuloplasmin was calreticulin. The artificial reticuloplasmin was a recombinant single-chain antibody (scFv), expressed with an N-terminal signal peptide and the C-terminal KDEL sequence for retrieval to the ER (scFvT84.66-KDEL). We found that both molecules were distributed in the same manner. In endosperm, each accumulated in ER-derived prolamine protein bodies, but also in glutelin protein storage vacuoles, even though glutelins are known to pass through the Golgi apparatus en route to these organelles. This finding may suggest that similar mechanisms are involved in the sorting of reticuloplasmins and rice seed storage proteins. However, the presence of reticuloplasmins in protein storage vacuoles could also be due to simple dispersal into these compartments during protein storage vacuole biogenesis, before glutelin deposition. In callus and leaf mesophyll cells, both reticuloplasmins accumulated in ribosome-coated vesicles probably derived directly from the rough ER.

Calcium-Binding Proteins↗
PubMed2000

Physical map of 17p13 and the genes adjacent to p53.

Genetic lesions in the p53 tumor suppressor gene are the most frequently observed alterations in human cancers. Typically in tumors, one allele of the p53 gene is initially mutated, followed by deletion of the remaining wildtype allele. In human colon cancer, for example, approximately 70% of late stage tumors are hemizygous mutant p53. Since the precise gene environment surrounding the p53 gene is not known, the neighboring genes concomitantly lost with wildtype p53 deletion remain undetermined. A restriction enzyme map and clone array of 1.1 Mb surrounding the p53 gene were constructed using a combination of YAC, BAC, NotI linking, and NotI jumping clones. The resulting physical map and clone array include approximately 400 kb telomeric and 700 kb centromeric to the p53 gene. Sequence determination and analysis adjacent to NotI and AscI sites, indicative of CpG islands, allowed the rapid identification of numerous genes within the cloned region. Twenty-seven transcription units were identified, including 18 characterized genes. Limited analysis of primary human colon tumors, hemizygous for the p53 gene, indicates loss of the entire 1.1-Mb region upon deletion of wildtype p53.

Chromosomes, Artificial, Yeast↗
PubMed2000

The nucleus: a highly organized but dynamic structure.

The nucleus in plants and animals is a highly structured organelle containing several well-defined subregions or suborganelles. These include the nucleolus, interphase chromosome territories and coiled bodies. We have visualized transcription sites in plants at both light- and electron-microscopy level by the incorporation of BrUTP. In the nucleolus many dispersed foci are revealed within the dense fibrillar component, each of which probably corresponds to a single gene copy. In the nucleoplasm there are also many dispersed foci of transcription, but not enough to correspond to one site per transcribed gene. We have shown that in wheat, and probably many other plant species, interphase chromosome territories are organized in a very regular way, with all the chromosomes in the Rabl configuration, all the centromeres clustered at the nuclear membrane and all the telomeres located at the nuclear membrane on the opposite side of the nucleus. However, despite this regular, polarized structure, there is no sign of polarization of transcription sites, or of any preferred location for them with respect to chromosome territorial boundaries. The nucleus is also highly dynamic. As an example, we have shown by the use of a green fluorescent protein fusion to the spliceosomal protein U2B" that coiled bodies move and coalesce within the nucleus, and may act as transport structures within the nucleus and nucleolus.

Autoantigens↗
PubMed2000

Widely separated multiple transgene integration sites in wheat chromosomes are brought together at interphase.

We have investigated the organization of transgenes delivered by particle bombardment into the wheat genome, combining conventional molecular analysis with fluorescence in situ hybridization (FISH) and three-dimensional confocal microscopy. We selected a representative population of transformed wheat lines and carried out molecular and expression analysis. FISH on metaphase chromosomes showed that transgene integration sites were often separated by considerable lengths of genomic DNA (>1 Mbp), or could even be on opposite chromosome arms. Plants showing multiple integration sites on a single chromosome were selected for three-dimensional confocal analysis of interphase nuclei in root and embryo tissue sections. Confocal microscopy revealed that these sites lay in close physical proximity in the interphase nuclei. Our results clearly show that multiple transgenes physically separated by large intervening regions of endogenous DNA at metaphase can be brought together at interphase. This may reflect the original physical organization of the endogenous DNA at the moment of transformation, with DNA strand breaks introduced into several co-localized DNA loops by the intruding gold particles. Alternatively, the transgenes may be brought together after transformation, either by an ectopic homologous pairing mechanism, or by recruitment to a common transcription site.

Chromosome Mapping↗
PubMed2000

Probing cortical sites of antipsychotic drug action with in vivo receptor imaging.

Imaging receptors using radioactive ligands has allowed direct determination of the sites of action of antipsychotic drugs. Initial studies relating antipsychotic drug efficacy to action at striatal dopamine D2-like receptors have recently been undermined. Developments in imaging extrastriatal dopamine D2-like receptors suggest rather that antagonism of these receptors in the temporal cortex is the common site of action for antipsychotic drugs, with occupancy at striatal receptors relating more closely to extrapyramidal side effects. Further work into dopamine receptor subtypes and other receptor groups such as serotonin and GABA neurotransmitters awaits the development of suitable probes, but there are some initial finding. Again a main site of antipsychotic drug action is at cortical levels with high degrees of cortical D1 and 5HT2a receptor occupancy attained particularly by atypical antipsychotic drugs.

Journal Article↗
PubMed2000

European cerebrospinal fluid consensus group--a TeamRoom (Lotus Notes)-based communication network.

A group of clinical neurochemists from all over Europe used TeamRoom to share information and to trace their discussions in a computer network. TeamRoom is a Lotus Notes based groupware tool enabling collaboration amongst geographically dispersed teams. As a result of this work a picture is emerging in the virtual TeamRoom space that represents a new kind of consensus in the use of cerebrospinal fluid analysis for diagnosis of neurological diseases. This kind of consensus differs from the conventional written report in giving a more complex and potentially richer representation of the field, in which both common views and minority perspectives are revealed. If direct access to this work is made available to other clinical neurochemists for consultation via a website, they may see their own practice in a wider context. This approach to improving different evolving traditions is more suitable for a global multicultural environment than a singular view of best practice produced by a more traditional process of group discussion. We refer to the benefits of a mixture of face to face meetings, collaboration in TeamRoom and teleconferencing for work in a non-hierarchical, multicultural and multilingual group. We suggest that the TeamRoom concept is a valuable model for enhancing self-organized harmonization across the developing European Union.

Computer Communication Networks↗
PubMed1999

Is radical trachelectomy a safe alternative to radical hysterectomy for patients with stage IA-B carcinoma of the cervix?

BACKGROUND: The prognosis associated with lymph node negative, early stage carcinoma of the cervix is excellent, with 5-year survival rates greater than 90%. Radical trachelectomy in combination with pelvic lymph node dissection (RVT + LPL) has emerged as an alternative to radical hysterectomy (RH) for these patients who desire preservation of fertility. However, there are limited data to support its efficacy and safety. METHODS: All patient information was collected prospectively and was subsequently extracted from the cervical cancer surgery database of the Division of Gynecologic Oncology at the University of Toronto. Patients treated by RVT + LPL for fertility preservation were compared with two groups of patients treated by RH. One control group was matched for age, tumor size, histology, depth of invasion, presence of capillary lymphatic space involvement, lymph node metastases, and use of adjuvant radiation. The other control group consisted of patients with tumor sizes </=2 cm, negative pelvic lymph nodes who had not received adjuvant radiation therapy. RESULTS: Thirty of 32 patients treated by RVT + LPL between March 1994 and November 1998 were matched. The only statistically significant difference in prognostic factors between the patients who underwent RVT + LPL and unmatched controls (556 patients) was the median depth of invasion in the adenocarcinomas (2. 0 mm vs. 4.0 mm, respectively; P < 0.02). The 2-year actuarial recurrence free survival was 95%, 100%, and 97% for the patients who underwent RVT + LPL, matched controls, and unmatched controls, respectively. The actuarial conception rate at 12 months was 37%. CONCLUSIONS: Acknowledging the small numbers and short follow-up, RVT + LPL appears to be similar in efficacy to RH. If longer follow-up with more patients confirms the above, this procedure will represent an acceptable alternative to RH for patients with early Stage I carcinoma of the cervix who desire preservation of fertility.

Adenocarcinoma↗
PubMed1999

Isolation, characterization and sequence analysis of five IgG monoclonal anti-beta 2-glycoprotein-1 and anti-prothrombin antigen-binding fragments generated by phage display.

We have isolated five monoclonal IgG anti-beta 2-glycoprotein-1 (anti-beta 2G-1) and anti-prothrombin Fab from a patient with autoantibodies to oxidized low-density lipoproteins by phage display method. Analysis of their binding specificity revealed that all three beta 2GP-1-enriched mAbs (B14, B22, B27) reacted with beta 2GP-1 while both prothrombin-isolated mAbs (P11 and P13) reacted with prothrombin. Intriguingly, mAb P11 reacted with beta 2GP-1 and prothrombin and showed comparable binding affinity to both Ags, with Kd values of 1.6 x 10-6 M for beta 2GP-1 vs 3.2 x 10-6 M for prothrombin. This clone may thus, define a hitherto unknown shared epitope between beta 2GP-1 and prothrombin. Sequence analysis of all five clones showed significant mutations of the expressed genes. One rearranged V-D-J segment was repeatedly employed by three clones (mAbs B22, B27, and P13). However, all three clones used different L chains. Of note, the pairing of VH6-D-J with the L5-Vk1 L chain in mAb P13 resulted in the loss of binding to beta 2GP-1 and specific reactivity to prothrombin. Together, these data suggest that while the VH6-D-J chain may be important in the binding to beta 2GP-1, pairing with certain L chains may influence this binding. These data are the first human IgG anti-beta 2GP-1 and anti-prothrombin sequences reported; both represent the major subsets of antiphospholipid Abs present in antiphospholipid syndrome patients.

Aged↗