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Biomedical subjects

J Spencer

Publications and source records attributed to J Spencer.

At least 127 records · Page 7Linked to original sources
PubMed1997

Identification of entero-aggregative Escherichia coli based on surface properties.

Twenty-nine strains of Escherichia coli that adhere to HEp-2 cells with a 'stacked brick' pattern (EAggEC), and four nonadherent control strains, were examined for the ability to hybridize with gene probes for aggregative (AA) and diffuse (DA) HEp-2 cell adhesion phenotypes. These strains were also tested for the ability to express an 18 kDa membrane-associated outer-membrane protein (MAP), to agglutinate erythrocytes, and to produce a pellicle during broth culture. Thirteen of the 29 HEp-2 adherent strains of E. coli hybridized with the gene probes for both AA and DA, and expressed an 18 kDa outer membrane protein (OMP) which was antigenically related to the MAP expressed by strains of E. coli O126:H27. The strains that did not carry the additional DA genes did not express an 18 kDa OMP. Although strains of EAggEC share the ability to adhere to HEp-2 cells with a stacked brick pattern, these strains exhibit a diverse range of physical and biochemical properties. From the results of this study, it was concluded that currently, the possession of EAggEC genes or the ability to adhere to HEp-2 cells in a stacked brick formation, remain the only reliable means of identifying EAggEC.

Bacterial Adhesion↗
PubMed1997

Analysis of TH1 and TH2 cytokine production in low grade B cell gastric MALT-type lymphomas stimulated in vitro with Helicobacter pylori.

Previous studies have suggested that the dependence of low grade B cell gastric lymphoma on infection of the gastric mucosa with Helicobacter pylori results from help provided by H pylori specific tumour infiltrating T cells. ELISPOT analysis was used to characterise functional subpopulations of tumour infiltrating T cells. The production of the TH1 cytokine interferon gamma and TH2 cytokines interleukin (IL)-4, IL-5, and IL-10 were measured in tumour cell suspensions from two cases of low grade B cell gastric lymphoma, one case of thyroid gland lymphoma, and one case of salivary gland lymphoma. Cells were assayed on day 0 and following 24 hours incubation either in culture medium or with a range of strains of H pylori. There was a dominant TH1-type (pro-inflammatory) response consistent with the TH1 response observed in H pylori gastritis.

Antigens, Bacterial↗
PubMed1997

Help clients develop hopes for the future.

The purposes of this article are (a) to examine cognitive, emotional, and spiritual aspects of hope as reflected in the literature; (b) to describe three clinical approaches that have been used in occupational therapy to engage clients in development of hopes for the future; and (c) to consider practical issues that have been raised by therapists seeking to incorporate development of hopes in their practice. Literature from health care and the social sciences indicates that cognitive, emotional, and spiritual aspects of hope are interwoven in a complex process that evolves over time after major loss. Three alternative clinical strategies for collaborating with clients in developing hopes are reviewed, including a goal-setting and goal-attainment approach, an occupational change approach, and a life history approach. These clinical strategies are illustrated by the stories of an elderly mental health client, an adult rehabilitation client, and an adolescent orthopedic client, which are drawn from research in which the authors have been involved. Discussion of issues involved in incorporating hope work into daily practice is based on the experiences of practicing therapists who participated in a workshop. These include pragmatic issues of documentation and reimbursement of this aspect of practice as well as clinical issues of how to develop hopes among clients who appear hopeless.

Adolescent↗
PubMed1997

Treatment of penicillin-resistant pneumococcus with penicillin: a case report.

Antibiotic resistance of Streptococcus pneumoniae is on the rise in many parts of the world, and varies widely across the United States. This is of growing concern as organisms become resistant to cephalosporins and macrolides as well as to beta-lactam antibiotics. Susceptibility testing has become a critical element in antibiotic selection. In vitro susceptibility, however, may not correlate with clinical susceptibility. For example, penicillin G in appropriate doses is often effective therapy for drug-resistant Streptococcus pneumoniae pneumonia. This report takes into account in vitro susceptibility as well as the patient's coexisting morbidities in the treatment of penicillin-resistant S pneumoniae with penicillin G.

Humans↗
PubMed1997

Risk adjustment of the postoperative mortality rate for the comparative assessment of the quality of surgical care: results of the National Veterans Affairs Surgical Risk Study.

BACKGROUND: The National Veterans Affairs Surgical Risk Study was designed to collect reliable, valid data on patient risk and outcomes for major surgery in the Veterans Health Administration and to report comparative risk-adjusted postoperative mortality rates for surgical services in Veterans Health Administration. STUDY DESIGN: This cohort study was conducted in 44 Veterans Affairs Medical Centers. Included were 87,078 major noncardiac operations performed under general, spinal, or epidural anesthesia between October 1, 1991, and December 31, 1993. The main outcomes measure was all-cause mortality within 30 days after the index procedure. Multivariable logistic regression risk-adjustment models for all operations and for eight surgical subspecialties were developed. Risk-adjusted surgical mortality rates were expressed as observed-to-expected ratios and were compared with unadjusted 30-day postoperative mortality rates. RESULTS: Patient risk factors predictive of postoperative mortality included serum albumin level, American Society of Anesthesia class, emergency operation, and 31 additional preoperative variables. Considerable variability in unadjusted mortality rates for all operations was observed across the 44 hospitals (1.2-5.4%). After risk adjustment, observed-to-expected ratios ranged from 0.49 to 1.53. Rank order correlation of the hospitals by unadjusted and risk-adjusted mortality rates for all operations was 0.64. Ninety-three percent of the hospitals changed rank after risk adjustment, 50% by more than 5 and 25% by more than 10. CONCLUSIONS: The Department of Veterans Affairs has successfully implemented a system for the prospective collection and comparative reporting of risk-adjusted postoperative mortality rates after major noncardiac operations. Risk adjustment had an appreciable impact on the rank ordering of the hospitals and provided a means for monitoring and potentially improving the quality of surgical care.

Cohort Studies↗
PubMed1997

Risk adjustment of the postoperative morbidity rate for the comparative assessment of the quality of surgical care: results of the National Veterans Affairs Surgical Risk Study.

BACKGROUND: The National Veterans Affairs Surgical Risk Study was designed to collect reliable, valid data on patient risk and outcomes for major surgery in the Veterans Health Administration and to report comparative risk-adjusted postoperative mortality and morbidity rates for surgical services in the Veterans Health Administration. STUDY DESIGN: This was a cohort study conducted at 44 Veterans Affairs Medical Centers closely affiliated with university medical centers. Included were 87,078 major noncardiac operations performed under general, spinal, or epidural anesthesia between October 1, 1991, and December 31, 1993. The main outcomes measures in this report are 21 postoperative adverse events (morbidities) occurring within 30 days after the index procedure. Multivariable logistic regression risk-adjustment models for all operations and for eight surgical subspecialties were developed. RESULTS: Patient risk factors predictive of postoperative morbidity included serum albumin level, American Society of Anesthesia class, the complexity of the operation, and 17 other preoperative risk variables. Wide variation in the unadjusted rates of one or more postoperative morbidities for all operations was observed across the 44 hospitals (7.4-28.4%). Risk-adjusted observed-to-expected ratios ranged from 0.49 to 1.46. The Spearman rank order correlation between the ranking of the hospitals based on unadjusted morbidity rates and risk-adjusted observed-to-expected ratios for all operations was 0.87. There was little or no correlation between the rank order of the hospitals by risk-adjusted morbidity and risk-adjusted mortality. CONCLUSIONS: The Department of Veterans Affairs has successfully implemented a system for the prospective collection and comparative reporting of postoperative mortality and morbidity rates after major noncardiac operations. Risk adjustment had only a modest effect on the rank order of the hospitals.

Female↗
PubMed1997

Gastric MALT lymphoma and Helicobacter pylori.

The majority of low grade gastric lymphomas arise within acquired organized lymphoid tissue, which has all the features of MALT. This MALT is specifically acquired most commonly in response to infection of the gastric mucosa by H pylori. The lymphocytes within this MALT are therefore programmed to respond to this organism and the neoplastic cells of the lymphoma that may develop within this acquired MALT retain the ability to respond to the immunological proliferative drive associated with the continued presence of the organism. Following the removal of this immunological drive by eradication of the organism in vivo, the lymphoma shows clinical and histological regression. The time required to see this response is unknown and there are some lymphomas that fail to respond to simple Helicobacter eradication. In some cases, there is continued molecular evidence of the presence of the lymphoma clone in low levels and the significance of this remains unknown. These factors are presently under detailed examination, and several clinical trials to assess the response of a large series of low grade gastric MALT lymphomas to anti-Helicobacter therapy and the requirement for additional chemotherapy are at present in progress.

Gastric Mucosa↗
PubMed1996

Domain behavior during the folding of a thermostable phosphoglycerate kinase.

Bacillus stearothermophilus phosphoglycerate kinase (bsPGK) is a monomeric enzyme of 394 residues comprising two globular domains (N and C), covalently linked by an interdomain alpha-helix (residues 170-185). The molecule folds to the native state in three stages. In the first, each domain rapidly and independently collapses to form an intermediate in which the N-domain is stabilized by 5.1 kcal mol-1 and the C-domain by 3.3 kcal mol-1 over their respective unfolded conformations. The N-domain then converts to a folded state at a rate of 1.2 s-1 (delta GI-F = 3.8 kcal mol-1), followed by the C-domain at 0.032 s-1 (delta GI-F = 12.1 kcal mol-1). It is this last step that limits the rate of acquisition of enzyme activity. In the dynamics of unfolding in water, the N-domain converts to the intermediate state at a rate of 8 x 10(-4) s-1, some 10(7) times faster than the C-domain. Consequently, the most populated intermediate in the folding reaction has a native-like N-domain, while that in the unfolding direction has a native-like C-domain. In a conventional sense, therefore, the folding/unfolding kinetics of bsPGK can be described as random order. Consistent with these observations, cutting the molecule in the interdomain helix produces two, independently stable units comprising residues 1-175 and 180-394. A detailed comparison of their folding behavior with that of the whole molecule reveals that true interdomain contacts are relatively weak, contributing approximately 1.4 kcal mol-1 to the stability of the active enzyme. The only interactions which contribute to the stability of rapidly formed intermediates or to transition states along the productive folding pathways are those within domain cores. Contacts formed either between domains or with the interdomain helix are made only in the folded ground state, but do not constitute a separate step in the folding mechanism. Intriguingly, the most pronounced effect of interdomain contacts on the kinetics of folding is inhibitory; the presence of the C-domain appearing to reduce the effective rate of acquisition of native structure within the N-domain.

Circular Dichroism↗
PubMed1996

Earth-Based Observations of the Galileo Probe Entry Site

Earth-based observations of Jupiter indicate that the Galileo probe probably entered Jupiter's atmosphere just inside a region that has less cloud cover and drier conditions than more than 99 percent of the rest of the planet. The visual appearance of the clouds at the site was generally dark at longer wavelengths. The tropospheric and stratospheric temperature fields have a strong longitudinal wave structure that is expected to manifest itself in the vertical temperature profile.

Journal Article↗
PubMed1996

Helicobacter pylori-specific tumour-infiltrating T cells provide contact dependent help for the growth of malignant B cells in low-grade gastric lymphoma of mucosa-associated lymphoid tissue.

Previous studies have shown that tumour cells from low-grade B-cell gastric lymphomas of mucosa-associated lymphoid tissue (MALT) type proliferate in vitro in response to heat-killed whole cell preparations of Helicobacter pylori, but only in the presence of tumour-infiltrating T cells. This response is strain-specific in that the tumours studied responded optimally to different strains of H. pylori. It was unclear from these studies, however, whether the ability to recognize the specific stimulating strains of H. pylori was a property of the tumour cells or the tumour-infiltrating T cells. This study shows that whereas the tumour cells do not respond to H. pylori, both freshly isolated tumour-infiltrating T cells and a T cell line derived from these cells proliferate in response to stimulating strains of H. pylori. T cells from the spleen of one of the patients do not share this property. These results suggest that B-cell proliferation in cases of low-grade gastric lymphoma of MALT type in vitro in response to H. pylori is due to recognition of H. pylori by tumour-infiltrating T cells, which in turn provide help for tumour cell proliferation. The observations provide an explanation for properties of gastric MALT-type lymphoma, such as regression following eradication of H. pylori and the tendency of the tumour to remain localized to the primary site.

Antigens, Bacterial↗
PubMed1996

p57K1P2 is expressed in Wilms' tumor with LOH of 11p15.5.

p57KIP2 is a cyclin-dependent kinase inhibitor that maps to human chromosome band 11p15.5, placing it in a genomically imprinted region that has been implicated in the etiology of Wilms' tumor and in the Beckwith-Wiedemann syndrome. Recent analysis of p57KIP2 expression in the mouse has determined that this gene is exclusively expressed from the maternal allele. It has been suggested that p57KIP2 is the WT2 tumor suppressor gene in the 11p15.5 region. We have used reverse transcriptase PCR to determine whether loss of p57KIP2 expression occurs in Wilms' tumor samples that have undergone maternal loss of heterozygosity of 11p15.5. p57KIP2 mRNA was amplified in both the Wilms' tumor tissue and in normal kidney tissue of all five patients analyzed. Semi-quantitative PCR analyses demonstrated that the relative level of p57KIP2 expression in tumor tissue is not markedly different from that in normal kidney. Our data indicate that if the p57KIP2 gene is imprinted in humans and expressed exclusively from the maternal allele, reactivation of the paternal allele has occurred in all five Wilms' tumor samples analyzed in this study. Sequence analysis of the p57KIP2 Cdk inhibitory domain in genomic DNA from primary and secondary tumors from two patients showed only a single base change in one secondary WT, resulting in a predicted methionine to isoleucine substitution at amino acid position 70. These studies suggest that p57KIP2 may not be the WT2 gene.

Alleles↗
PubMed1996

Demonstration of local clonality of mucosal T cells in human colon using DNA obtained by microdissection of immunohistochemically stained tissue sections.

Intraepithelial lymphocytes have been shown to be oligoclonal and to be disseminated widely along the human intestine. However, studies using monoclonal antibodies have suggested that superimposed on the widespread clones, there is local variability in the mucosal T cell population. We have investigated the possibility that local dominant clones of T cells are present in the colonic mucosa by polymerase chain reaction (PCR) amplification of T cell receptor beta chain junctional regions using DNA extracted from microdissected fragments of tissue sections. Colon from two right hemicolectomy specimens was sampled at 7-cm intervals. Adjacent areas of mucosa were microdissected from sections from each colon sample. When the PCR products were separated according to size on polyacrylamide gels, bands of identical size were often observed when DNA extracted from adjacent fragments of mucosa had been used. Different bands were present when the different samples of colon had been studied. Sequencing of the PCR products confirmed that clonally related T cells were present in adjacent areas of mucosa, whereas different clones dominated at distant sites. DNA extracted from cells microdissected from the T cell zone of Peyer's patch was treated identically. The sequences obtained from the Peyer's patch, as expected, were diverse. However, one of the sequences identified was identical to that of one of the clones in the colon, implying that this clone was either trafficking through the Peyer's patch or possibly originated from the Peyer's patch. In this study, we also identified the Peyer's patches as a site of proliferation of CD4+ T cells. No T cell division was observed in the lamina propria. The molecular and immunohistochemical observations together support the hypothesis that the Peyer's patches are a source of mucosal T cells.

Adenocarcinoma↗