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Biomedical subjects

B Carlson

Publications and source records attributed to B Carlson.

At least 55 records · Page 3Linked to original sources
PubMed1998

Antibody-directed superantigen-mediated T-cell killing of myeloid leukaemic cell line cells.

Bacterial superantigens (SAgs) bound to MHC class II molecules on target cells are efficient activators of cytotoxic T cells expressing certain T cell receptor (TCR) Vbeta regions We described earlier that the specificity of the SAg Staphylococcus enterotoxin A (SEA) can be changed by introducing a D227A point mutation in the major MHC class II binding site and by genetically fusing the SEA mutant (SEAm) to protein A (PA). This SEAm-PA fusion protein can then be used to direct cytotoxic T cells to tumour cells coated with monoclonal antibodies (mAbs). In this communication, we tested the PA-SEAm fusion protein together with mAbs against the myeloid cell surface antigens CD13, CD15 and CD33. A SEA-reactive T cell line was used as effector cells against 10 different myeloid leukaemic cell lines. Optimal lysis of antigen positive leukaemic cells was obtained at a PA-SEAm concentration of 1 ng/ml and effector : target cell ratios of 15 : 1. No correlation between target cell sensitivity and the level of surface antigen expression could be seen. The 6 acute myeloid leukaemia (AML) cell lines tested appeared to be more sensitive than the 4 chronic myeloid leukaemia (CML) cell lines. The sensitivity of the AML cell line HL-60 could be improved further by stimulation with TNFalpha. This was accompanied by increased surface ICAM-1 expression whereas specific target molecule expression (CD13, CD33) was unchanged. This suggests that sensitivity to lysis is related to the leukaemic subtype and ICAM-1 expression but not to the tumour antigen density. Our results show that it is possible to direct cytotoxic T cells to myeloid leukaemia cells by using SAgs linked to mAbs, and encourage the construction and testing of a recombinant direct SAg-mAb fusion protein as a candidate drug for therapy of myeloid leukaemias.

Antibodies, Monoclonal↗
PubMed1998

Action STAT! The crisis nurse.

To provide quality care with limited staff and create a safer environment, managers created a new "crisis nurse" position.

Emergency Service, Hospital↗
PubMed1997

Molecular phylogeny and evolution of the neurotrophins from monotremes and marsupials.

We have investigated the phylogenetic relationships of monotremes and marsupials using nucleotide sequence data from the neurotrophins; nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3). The study included species representing monotremes, Australasian marsupials and placentals, as well as species representing birds, reptiles, and fish. PCR was used to amplify fragments encoding parts of the neurotrophin genes from echidna, platypus, and eight marsupials from four different orders. Phylogenetic trees were generated using parsimony analysis, and support for the different tree structures was evaluated by bootstrapping. The analysis was performed with NGF, BDNF, or NT-3 sequence data used individually as well as with the three neurotrophins in a combined matrix, thereby simultaneously considering phylogenetic information from three separate genes. The results showed that the monotreme neurotrophin sequences associate to either therian or bird neurotrophin sequences and suggests that the monotremes are not necessarily related closer to therians than to birds. Furthermore, the results confirmed the present classification of four Australasian marsupial orders based on morphological characters, and suggested a phylogenetic relationship where Dasyuromorphia is related closest to Peramelemorphia followed by Notoryctemorphia and Diprotodontia. These studies show that sequence data from neurotrophins are well suited for phylogenetic analysis of mammals and that neurotrophins can resolve basal relationships in the evolutionary tree.

Amino Acid Sequence↗
PubMed1997

Intranasal immunization with C5a peptidase prevents nasopharyngeal colonization of mice by the group A Streptococcus.

Early inflammatory events are initiated by phased production of C5a and interleukin-8 in tissue. Most serotypes of group A streptococci express a surface-bound peptidase (SCPA) which specifically cleaves mouse and human C5a chemotaxins. This study investigates the impact of SCPA on colonization of the nasopharyngeal mucosa of mice and evaluates its potential to induce protective immunity. Two strains, serotypes M6 and M49, which contain insertion and deletion mutations in the SCPA gene (scpA) and represent the two major subdivisions of group A streptococci, were characterized and compared in a mouse intranasal infection model. In this model, SCPA mutants were more rapidly cleared from the nasopharynges of inoculated mice compared with wild-type strains. A 2,908-bp fragment of scpA49 gene, obtained by PCR, was ligated to the expression vector pGEX-4T-1 and expressed in Escherichia coli. The affinity-purified deltaSCPA49 protein proved to be highly immunogenic in mice and rabbits. Although the purified deltaSCPA49 immunogen lacked enzymatic activity, it induced high titers of rabbit antibodies which were able to neutralize peptidase activity associated with M1, M6, M12, and M49 streptococci in vitro. This result confirmed that antipeptidase antibodies lack serotype specificity. Intranasal immunization of mice with the deleted form of the SCPA49 protein stimulated significant levels of specific salivary secretory immunoglobulin A (IgA) and serum IgG antibodies and reduced the potential of wild-type M1, M2, M6, M11, and M49 streptococci to colonize. These experiments suggest a new approach to vaccine development for prevention of streptococcal pharyngitis.

Adhesins, Bacterial↗
PubMed1996

Are nurses still practicing coronary precautions? A national survey of nursing care of acute myocardial infarction patients.

BACKGROUND: Coronary precautions were common when coronary care units were instituted in the 1960s. However, research has failed to provide evidence of the validity of most of these restrictions. Only the avoidance of the Valsalva maneuver is clearly indicated as a universal precaution in patients who have experienced acute myocardial infarction. OBJECTIVES: To determine if nurses continue to restrict iced and hot fluids, caffeine, rectal temperature measurement, and vigorous back rubs, and to feed and mandate bedrest for acute myocardial infarction patients. METHODS: Survey techniques were used to describe practice patterns of nurses working in hospitals across the United States. Two sampling methods were used to access a random sample. The survey was mailed to members of the American Association of Critical-Care Nurses and nonmembers working in a hospital accredited by the American Hospital Association and with an intensive care unit. RESULTS: Of the 2549 mailed surveys, 882 were returned with usable data (34.8% response rate). Iced (28.1%) and hot (8.7%) fluids continued to be restricted by nurses. Most (85.6%) restricted stimulant beverages such as coffee. Rectal temperature measurement was avoided by 55.7%, and only 73.3% taught avoidance of the Valsalva maneuver. In terms of rest, 15.6% reported avoiding vigorous back rubs, 8.4% still fed patients, and 33.8% offered bedpans to pain-free patients on the first day after admission. A complete bedbath was offered by 19.8% of nurses to stable, pain-free patients even a day after admission. CONCLUSIONS: The data supporting liberalization of coronary precautions have not been adequately disseminated.

Adult↗
PubMed1995

The role of endoscopic retrograde cholangiopancreatography in patients with laparoscopic cholecystectomies.

BACKGROUND & AIMS: The best clinical strategy for using endoscopic retrograde cholangiopancreatography (ERCP) with laparoscopic cholecystectomy is unknown. The aim of this study is to use decision analysis to assess four different approaches to using ERCP in patients undergoing laparoscopic cholecystectomy. METHODS: Decision trees were designed for four clinical strategies: (1) preoperative ERCP, with sphincterotomy for choledocholithiasis; (2) selective preoperative ERCP for patients at high risk for choledocholithiasis, choledocholithiasis found at surgery treated by postoperative ERCP; (3) no preoperative ERCP, choledocholithiasis detected intraoperatively treated by postoperative ERCP; and (4) no preoperative ERCP, choledocholithiasis detected intraoperatively treated with open common bile duct exploration. Using decision analysis with literature-derived data, the impact on outcome parameters was calculated. RESULTS: Postoperative ERCP resulted in the lowest cost, procedure numbers, and hospital and back-to-work days. With high preoperative likelihood of choledocholithiasis, selective preoperative ERCP was probably a clinically equivalent strategy. Sensitivity analysis supported these conclusions when the probabilities and utilities were varied over a wide range. The open operative approach to choledocholithiasis was only favored if ERCP had < 75% diagnostic and < 50% therapeutic success rates or lengthened hospitalization by > 7 days. CONCLUSIONS: This study suggests that performing ERCP after laparoscopic cholecystectomy minimizes costs and morbidity; however, when choledocholithiasis is likely, selective preoperative ERCP may be a clinically equivalent strategy.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1995

Monitoring electrocardiographic changes: results of a national survey.

This article describes the electrocardiographic (ECG) monitoring practices of a national sample of nurses caring for patients who have suffered an acute myocardial infarction (AMI). Of specific interest were lead section practices, diagnosis of infarct evolution, and use of right precordial leads. Two populations were randomly sampled in an attempt to minimize sampling bias. Of the 2,549 mailed surveys, 882 were returned (34.8% response rate) from 48 states. Lead II was used most commonly (66.3%) with a single-channel system. Lead II plus V1 (or MCL1) was selected most often (62.4%) with dual-channel systems. Few (20%) respondents reported "always" modifying lead selection based on location of AMI; selected most often (62.4%) with only 43.3% correctly identified classic ischemia, injury, and infarction. Right precordial leads are used infrequently in practice.

Chi-Square Distribution↗