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Biomedical subjects

B Williamson

Publications and source records attributed to B Williamson.

At least 19 recordsLinked to original sources
PubMed2004

An efficient transformation system for chickpea (Cicer arietinum L.).

A reproducible and efficient transformation method was developed for Desi and Kabuli chickpeas (Cicer arietinum L.) using germinated seedlings as sources of explants. Slices derived from plumules were the most efficient at generating transformed shoots. The AGL1 Agrobacterium-treated explants were first incubated on thidiazuron-containing media, then selected using phosphinothricin. Resistant shoots were successfully transferred to soil either by grafting or in vitro rooting. In experiments each taking 4-9 months, a total of 41 confirmed transformed lines were created using embryo axis slices as source explants, giving a transformation frequency of 5.1%. Southern analysis and histochemical and leaf painting assays demonstrated integration and expression of the transgenes in the initial transformants and two generations of progeny.

Cicer↗
PubMed2003

Medical staff's knowledge of pulse oximetry: a prospective survey conducted in a tertiary children's hospital.

OBJECTIVES: To assess the knowledge of pulse oximetry of senior (SMO) and junior medical officers (JMO) in a tertiary paediatric hospital. METHODS: A 16-item multiple choice questionnaire was administered to SMO and JMO without prior notice or instruction in the area. The questions were completed voluntarily and anonymously, then proctored and collated by the principal investigator. RESULTS: The mean test scores for SMO and JMO were 70 +/- 15% and 65 +/- 13%, respectively (P = 0.06). A significant negative correlation was found between the test scores and the years of paediatric experience with the SMO. CONCLUSIONS: The results of the survey showed there is an insufficiency of knowledge and understanding among medical staff concerning the principles, clinical applications and limitations of pulse oximetry. More emphasis needs to be placed on teaching these principles to ensure quality care for patients.

Australia↗
PubMed2002

Infection of leaves of Arabidopsis thaliana by Botrytis cinerea: changes in ascorbic acid, free radicals and lipid peroxidation products.

Infection of leaves of Arabidopsis thaliana with conidial suspensions of the necrotrophic pathogen Botrytis cinerea resulted in a large decrease in the level of ascorbic acid and increases in intensity of a single-peak free radical and Fe(III) (g=4.27) signals in electron paramagnetic resonance (EPR) spectra. These changes were not confined to the spreading lesions or associated areas of chlorosis, but extended to other apparently healthy tissues in the infected leaves. They are, therefore, consistent with the existence of high levels of oxidative stress being generated as a result of the infection process. The expected accompanying increases in levels of the aldehydic products of lipid peroxidation, malondialdehyde (MDA) and 4-hydroxy-2-nonenal (4-HNE), were not observed, and in the case of MDA the levels in tissue from infected plants were appreciably lower than in the healthy controls. These last findings are surprising and demonstrate a difference in the response of A. thaliana to infection with B. cinerea compared with tissues from other plant families studied previously.

Aldehydes↗
PubMed2001

Immunohistochemical analysis of NY-ESO-1 antigen expression in normal and malignant human tissues.

NY-ESO-1, a member of the CT (cancer/testis) family of antigens, is expressed in normal testis and in a range of human tumor types. Knowledge of NY-ESO-1 expression has depended on RT-PCR detection of mRNA and there is a need for detecting NY-ESO-1 at the protein level. In the present study, a method for the immunochemical detection of NY-ESO-1 in paraffin-embedded tissues has been developed and used to define the expression pattern of NY-ESO-1 in normal tissues and in a panel of human tumors. No normal tissue other than testis showed NY-ESO-1 reactivity, and expression in testis was restricted to germ cells particularly spermatogonia. In human tumors, the frequency of NY-ESO-1 antigen expression corresponds with past analysis of NY-ESO-1 mRNA expression e.g., 20-30% of lung cancers, bladder cancers and melanoma, and no expression in colon and renal cancer. Co-typing of NY-ESO-1 antigen and mRNA expression in a large panel of lung cancers showed a good correlation. There is great variability in NY-ESO-1 expression in individual tumors, ranging from an infrequent homogeneous pattern of staining to highly heterogeneous antigen expression.

Antibodies, Monoclonal↗
PubMed2001

Humoral immunity to human breast cancer: antigen definition and quantitative analysis of mRNA expression.

The ability of the immune system to recognize structurally altered, amplified or aberrantly expressed proteins can be used to identify molecules of etiologic relevance to cancer and to define targets for cancer immunotherapy. In the current study, ninety-four distinct antigens reactive with serum IgG from breast cancer patients were identified by immunoscreening breast cancer-derived cDNA expression libraries (SEREX). A serological profile was generated for each antigen on the basis of reactivity with allogeneic sera from normal individuals and cancer patients, and mRNA expression profiles for coding sequences were assembled based upon the tissue distribution of expressed sequence tags, Northern blots and real-time RT-PCR. Forty antigens reacted exclusively with sera from cancer patients. These included well-characterized tumor antigens, e.g. MAGE-3, MAGE-6, NY-ESO-1, Her2neu and p53, as well as newly-defined breast cancer antigens, e.g. kinesin 2, TATA element modulatory factor 1, tumor protein D52 and MAGE D, and novel gene products, e.g. NY-BR-62, NY-BR-75, NY-BR-85, and NY-BR-96. With regard to expression profiles, two of the novel gene products, NY-BR-62 and NY-BR-85, were characterized by a high level of testicular mRNA expression, and were overexpressed in 60% and 90% of breast cancers, respectively. In addition, mRNA encoding tumor protein D52 was overexpressed in 60% of breast cancer specimens, while transcripts encoding SNT-1 signal adaptor protein were downregulated in 70% of these cases. This study adds to the growing list of breast cancer antigens defined by SEREX and to the ultimate objective of identifying the complete repertoire of immunogenic gene products in human cancer (the cancer immunome).

Antibody Formation↗
PubMed2001

Botrytis cinerea induces the formation of free radicals in fruits of Capsicum annuum at positions remote from the site of infection.

Free radical adducts of the spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone have been observed by electron paramagnetic resonance spectroscopy in detached fruits of Capsicum annuum investigated 5 days after infection with Botrytis cinerea. The spectra of these adducts were at a maximum within the soft rot lesion, but they could also be detected at distances up to 50 mm from the edge of the lesion in samples following main vascular bundles. At distances greater than 40 mm, the spectrum of the ascorbate radical was also seen, and at greater distances from the lesion it was the only radical detected. With samples taken from parenchyma tissue adjacent to the vascular bundles there was little adduct formation and the ascorbate radical could be detected, albeit with reduced intensity compared to healthy tissue, at distances as small as 10 mm from the edge of the lesion. This observation of chemical changes at considerable distances from the infected tissue is in contrast to previous observations on the behaviour of other markers of oxidative stress (e.g., 4-hydroxynonenal, malondialdehyde, single-peak free radical, and Fe(III) (g = 4.27) electron paramagnetic resonance signals), where their levels decreased rapidly outside of the soft rot.

Botrytis↗
PubMed2001

Markers for oxidative stress associated with soft rots in French beans (Phaseolus vulgaris) infected by Botrytis cinerea.

The role of active oxygen species has been studied in spreading soft-rot lesions caused by the necrotrophic fungal pathogen Botrytis cinerea Pers.:Fr. in leaves of four genotypes of French bean (Phaseolus vulgaris L.). Large increases were observed for the aldehydic end-products of oxidative damage, malondialdehyde and 4-hydroxy-2-nonenal, as a result of infection in each of the genotypes studied. Similar increases were found in a stable free radical and g=4.27 Fe(III) signals, but not Mn(II) signals, in electron paramagnetic resonance spectra. These changes were accompanied by large decreases in ascorbic acid levels, with changes in the antioxidant glutathione being genotype dependent.

Aldehydes↗
PubMed2001

Botrydial is produced in plant tissues infected by Botrytis cinerea.

The fungal metabolite botrydial was detected for the first time in ripe fruits of sweet pepper (Capsicum annuum) wound-inoculated with conidial suspensions of Botrytis cinerea and also in leaves of Phaseolus vulgaris and Arabidopsis thaliana inoculated without wounding. This phytotoxin was produced in soft rot regions of the infection. In C. annuum, the most aggressive isolate produced the highest botrydial concentrations in planta. The levels of botrydial produced by this isolate did not correlate with the reported relative susceptibilities of four P. vulgaris genotypes. The results suggest that botrydial is a pathogenicity factor for this fungus, but not a primary determinant of pathogenicity.

Aldehydes↗
PubMed2001

Immunohistochemical and reverse transcription-polymerase chain reaction expression analysis of tyrosinase and microphthalmia-associated transcription factor in angiomyolipomas.

Angiomyolipomas (AMLs) show a characteristic immunoreactivity with melanocyte differentiation markers such as monoclonal antibody (mAb) HMB45, which detects melanocyte differentiation antigen gp100 and mAb A103 reacting with Melan-A/MART-1. Monoclonal antibody T311 to tyrosinase (a key enzyme of melanogenesis) and mAb D5 to the microphthalmia (Mitf) antigen are two newly available markers of melanocytic differentiation. The authors tested 15 AMLs with T311 and D5 by immunohistochemistry and a subset of 3 cases by reverse transcription-polymerase chain reaction for their expression of tyrosinase and Mitf mRNA. T311 showed poor sensitivity in AMLs because only focal staining was seen in 1 out of 15 cases, although tyrosinase mRNA was found in all tested cases. Mitf mRNA was present in 3 of 3 tested cases, and D5 was positive in 15 of 15 AMLs. However, D5 immunostaining often was focal and not as homogeneous as A103, which was analyzed in a previous study. D5 staining also could be seen in other cell types such as normal renal tubular cells, macrophages, and renal cell carcinoma. The current results show that in contrast with HMB45 and A103, T311 has little or no value in the diagnosis of AMLs. D5 may be useful in a panel of antibodies in the diagnosis of AMLs.

Angiomyolipoma↗
PubMed2000

Expression of cancer-testis antigens in lung cancer: definition of bromodomain testis-specific gene (BRDT) as a new CT gene, CT9.

In an effort to define new cancer-testis (CT) genes, we investigated whether BRDT, a testis-restricted member of the RING3 family of transcriptional regulators, is also expressed in cancer. Standard RT-PCR expression analysis detected BRDT transcripts in 12 of 47 cases of non-small cell lung cancer and single cases of both squamous cell carcinoma of the head and neck (1/12) and esophagus (1/12) but not in melanoma or in cancers of the colon, breast, kidney and bladder. Typing of 33 non-small cell lung cancers for coexpression of a panel of CT antigens revealed a high incidence (60%) of MAGE-3 mRNA expression, followed by MAGE-1 (36%), CT7/MAGE-C1 (30%), CT10 (30%), SSX4 (23%), BRDT (21%), NY-ESO-1 (21%) and HOM-MEL-40/SSX2 (15%). The coexpression pattern of these antigens provides a foundation for developing a polyvalent lung cancer vaccine.

Antigens, Neoplasm↗
PubMed2000

Providing visual information to validate 2-D to 3-D registration.

This paper addresses a key issue of providing clinicians with visual information to validate the accuracy of 2-D/3-D registration for robot-assisted total hip replacement (THR) surgery. Although numerous registration approaches have been presented, the topic of registration validation has scarcely been addressed in the literature. In practice, clinicians rely on post-operative X-rays to assess the accuracy of implant placement. Motivated by this, we simulate a set of post-operative X-ray images by superimposing the implant positioned pre-operatively onto the intra-operatively collected and calibrated images of the femur, through a transformation computed by the 2-D/3-D registration. With these images, a judgment on the registration accuracy can be made. In addition, this paper introduces methods for superimposing pre-operative data on intra-operative X-ray images that were not corrected for distortion, by applying the same image distortion to the data. This paper also introduces a new framework for incorporating surface normals in the objective function for registration. A comparison between marker-based and image-based registration is conducted. The advantage of our approach is that the simulated post-operative X-ray images are very familiar to clinicians and, therefore, easy for them to interpret. As an added benefit, this technique provides new means for comparing the marker-based and image-based registration for robot-assisted THR surgery. This approach can be extended to other interventions where intra-operative images are used for registration.

Arthroplasty, Replacement, Hip↗
PubMed2000

Monoclonal antibody MA454 reveals a heterogeneous expression pattern of MAGE-1 antigen in formalin-fixed paraffin embedded lung tumours.

Cancer/testis (CT) antigens such as those encoded by the MAGE-gene family are expressed in a wide variety of malignant neoplasms. In normal tissues, expression is generally restricted to testis. Current knowledge of the expression pattern of CT antigens is mainly based on mRNA analysis. Little is known about actual protein expression. We previously developed MA454, a monoclonal antibody (mAb) to MAGE-1 recombinant protein. By employing antigen retrieval techniques, we show that MA454 is reactive on formalin-fixed paraffin-embedded tissues. Immunohistochemical (IHC) analysis of a normal tissue panel revealed staining solely in germ cells of testes. A series of 59 lung tumours was co-typed for MAGE-1 expression by RT-PCR and by immunohistochemistry with MA454. MA454 was positive in 19/59 cases (32%). MAGE-1 mRNA was found in 17 of the 54 cases (32%) available for RT-PCR. Of the 19 MA454-reactive tumours, 15 showed a highly heterogeneous pattern of expression. The other 4 MA454 positive cases revealed immunoreactivity in >25% of tumour areas. Of the 53 cases typed for both, mRNA and protein expression, 48 co-typed whereas 5 cases were discrepant, a likely consequence of heterogeneous MAGE-1 expression. The predominantly focal expression of MAGE-1 suggests that this antigen might not be sufficient as a sole target for immunotherapeutic approaches.

Antibodies, Monoclonal↗
PubMed1999

Antigens recognized by autologous antibody in patients with renal-cell carcinoma.

The screening of cDNA expression libraries derived from human tumors with autologous antibody (SEREX) is a powerful method for defining the structure of tumor antigens recognized by the humoral immune system. Sixty-five distinct antigens (NY-REN-1 to NY-REN-65) reactive with autologous IgG were identified by SEREX analysis of 4 renal cancer patients and were characterized in terms of cDNA sequence, mRNA expression pattern, and reactivity with allogeneic sera. REN-9, -10, -19, and -26 have a known association with human cancer. REN-9 (LUCA-15) and REN-10 (gene 21) map to the small cell lung cancer tumor suppressor gene locus on chromosome 3p21.3. REN-19 is equivalent to LKB1/STK11, a gene that is defective in Peutz-Jeghers syndrome and cancer. REN-26 is encoded by the bcr gene involved in the [t(9:22)] bcr/abl translocation. Genes encoding 3 of the antigens in the series showed differential mRNA expression; REN-3 displays a pattern of tissue-specific isoforms, and REN-21 and REN-43 are expressed at a high level in testis in comparison to 15 other normal tissues. The other 62 antigens were broadly expressed in normal tissues. With regard to immunogenicity, 20 of the 65 antigens reacted only with autologous sera. Thirty-three antigens reacted with sera from normal donors, indicating that their immunogenicity is not restricted to cancer. The remaining 12 antigens reacted with sera from 5-25% of the cancer patients but not with sera from normal donors. Seventy percent of the renal cancer patients had antibodies directed against one or more of these 12 antigens. Our results demonstrate the potential of the SEREX approach for the analysis of the humoral immune response against human cancer.

Aged↗
PubMed1999

Isoforms of the human PDZ-73 protein exhibit differential tissue expression.

Patients with renal and colon cancer frequently develop IgG autoantibodies toward the NY-CO-38/PDZ-73 antigen, a protein of 652 amino acids (73 kDa) which contains three copies of the PDZ protein-protein interaction domain. The gene encoding PDZ-73 mapped to chromosome 11p15.4-p15.1. Additional tissue-specific isoforms were identified: PDZ-45, which lacks the third PDZ domain and the putative PEST protein degradation motif, is expressed in kidney, colon, small intestine, brain and testis; PDZ-54 and PDZ-59, which also lack the third PDZ domains, have unique carboxyl terminal amino acids and are expressed in brain, kidney, bladder, colon cancer and renal cancer; and a putative PDZ-37 isoform, containing only the third PDZ domain, that is expressed in the central nervous system. Immunohistochemical staining with anti-PDZ 73 monoclonal antibodies showed strong cytoplasmic reactivity in epithelial cells of the small intestine, colon and kidney tubules, with a prominent apical staining pattern in cells of the small intestine. The reactivity pattern of the antibodies with various tissues correlated with the mRNA expression pattern of the PDZ-45 isoform. The existence of multiple PDZ-73 isoforms with variations in tissue distribution, PDZ domains, protein degradation sequences and carboxyl terminal structure indicate that these isoforms have distinct tissue-specific functions.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Electronic imaging and clinical implementation: work group approach at Mayo Clinic, Rochester.

Electronic imaging clinical implementation strategies and principles need to be developed as we move toward replacement of film-based radiology practices. During an 8-month period (1998 to 1999), an Electronic Imaging Clinical Implementation Work Group (EICIWG) was formed from sections of our department: Informatics Lab, Finance Committee, Management Section, Regional Practice Group, as well as several organ and image modality sections of the Department of Diagnostic Radiology. This group was formed to study and implement policies and strategies regarding implementation of electronic imaging into our practice. The following clinical practice issues were identified as key focus areas: (1) optimal electronic worklist organization; (2) how and when to link images with reports; (3) how to redistribute technical and professional relative value units (RVU); (4) how to facilitate future practice changes within our department regarding physical location and work redistribution; and (5) how to integrate off-campus imaging into on-campus workflow. The EICIWG divided their efforts into two phases. Phase I consisted of Fact finding and review of current practice patterns and current economic models, as well as radiology consulting needs. Phase II involved the development of recommendations, policies, and strategies for reengineering the radiology department to maintain current practice goals and use electronic imaging to improve practice patterns. The EICIWG concluded that electronic images should only be released with a formal report, except in emergent situations. Electronic worklists should support and maintain the physical presence of radiologists in critical areas and direct imaging to targeted subspecialists when possible. Case tools should be developed and used in radiology and hospital information systems (RIS/HIS) to monitor a number of parameters, including professional and technical RVU data. As communication standards improve, proper staffing models must be developed to facilitate electronic on-campus and off-campus consultation.

Diagnostic Imaging↗