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Biomedical subjects

K Thompson

Publications and source records attributed to K Thompson.

At least 37 records · Page 2Linked to original sources
PubMed1992

Secondary pancreatic infections: are they distinct clinical entities?

BACKGROUND: Infected pseudocysts, pancreatic abscesses, and infected pancreatic necroses have been proposed as distinct clinical entities in terms of treatment and outcome. To evaluate this classification, we reviewed the clinical course and bacteriologic findings of pancreatic infections. METHODS: Of 1299 patients with pancreatitis or a related complication admitted over a 7-year period, 64 (4.9%) with culture-documented secondary pancreatic infections were reviewed with regard to cause, clinical course, bacteriologic findings, and outcomes. RESULTS: Group I consisted of 23 patients with infected pseudocysts; group II, 20 patients with pancreatic abscesses; and group III, 21 patients with infected pancreatic necrosis. The causes were alcohol in 36%, biliary tract disease in 30%, and postoperative in 16%, with no significant difference between groups. Patients in group I had abdominal pain or a mass without accompanying signs of sepsis, whereas patients in groups II and III had sepsis. In group I, 15 patients were treated with internal drainage, four with percutaneous drainage, and four with external drainage. In group II, three had percutaneous drainage, 15 operative drainage, and two open packing. In group III, 19 patients had operative drainage and two had open packing. Morbidity occurred in 26% of patients in group I, 40% in group II, and 90% in group III (p less than 0.001). Mortality rates were 9% in group I, 25% in group II, and 48% in group III (p less than 0.01). Enteric organisms were present in 66% of isolates, with no difference between groups, suggesting a common mode of infection. CONCLUSIONS: Despite similar bacteriologic findings, infected pseudocysts, pancreatic abscesses, and infected pancreatic necroses have significantly different presentations, clinical courses, and outcomes, confirming that they are distinct entities. This distinction is important when therapeutic outcomes are compared.

Abscess↗
PubMed1992

IgM rheumatoid factors in patients with rheumatoid arthritis derive from a diverse array of germline immunoglobulin genes and display little evidence of somatic variation.

Rheumatoid factors (RF) are present in the plasma of patients with rheumatoid arthritis (RA) although the site of synthesis of most of these antibodies is within the synovium. This report primary concerns RF of the IgM isotype. While a few of the RF derive from patients with systemic lupus erythematosus or from normal individuals, the remaining derive from the inflamed synovial tissue of patients with RA. Two RF are encoded by members of the VH1 gene family, 8 from the VH3 family and 2 from the VH4 family. Two polyreactive antibodies derive from the VH3 family and 2 come from the VH4 family. This distribution is not fundamentally different from the distributions seen in a large array of autoantibodies and antibodies to external antigens. Similarly, the light chains derive from most of the known kappa and lambda VL families. It is hard to escape the preliminary conclusion that gene segments from virtually any light chain variable region can contribute to RF or polyreactive antibody structures. Most IgM RF and polyreactive antibodies are direct copies of germline genes in one of their polypeptide chains or at most are 2 nucleotides away in one of their chains from a known germline gene.

Antibody Formation↗
PubMed1991

Interaction of the alpha beta dimers of the insulin-like growth factor I receptor is required for receptor autophosphorylation.

We have recently found that association of the two alpha beta dimers of the insulin-like growth factor I (IGF I) receptor is required for formation of a high-affinity binding site for IGF I [Tollefsen, S. E., & Thompson, K. (1988) J. Biol. Chem. 263, 16267-16273]. To determine the structural requirements for IGF I activated kinase activity, we have examined the effect of dissociation of the two alpha beta dimers of the IGF I receptor on beta subunit autophosphorylation. The alpha beta dimers formed after treatment with 2 mM dithiothreitol (DTT) at pH 8.75 for 5 min were separated from IGF I receptor remaining as tetramers after DTT treatment by fast protein liquid chromatography on a Superose 6 gel filtration column. Purification of the alpha beta dimers was confirmed by Western blot analysis using 125I-labeled alpha IR-3, a monoclonal antibody to the IGF I receptor. Autophosphorylation of the IGF I receptor (alpha beta)2 tetramer, treated without DTT or remaining after DTT treatment, is stimulated 1.6-2.9-fold by IGF I. In contrast, autophosphorylation of the alpha beta dimers incubated in the presence or absence of IGF I (100 ng/mL) does not occur. Both IGF I receptor dimers and tetramers exhibit similar kinase activities using the synthetic substrate Arg-Arg-Leu-Ile-Glu-Asp-Ala-Glu-Tyr-Ala-Ala-Arg-Gly, indicating that the failure to detect autophosphorylation of the IGF I receptor dimers does not result from inactivation of the kinase by DTT treatment. We conclude that autophosphorylation of the IGF I receptor depends upon the interaction of the two alpha beta dimers.

Adenosine Triphosphate↗
PubMed1991

Molecular cloning in Lactobacillus helveticus by plasmid pSA3::pVA797 co-integrate formation and conjugal transfer.

A gene encoding beta-glucanase activity from Bacillus amyloliquefaciens was subcloned in both orientations into plasmid shuttle vector pSA3. In only one orientation could a co-integrate be generated with the conjugative plasmid pVA797. The plasmid co-integrate was conjugated into Lactobacillus helveticus strain CNRZ450, where it was stably maintained without antibiotic selection and exhibited beta-glucanase activity. This method of introducing cloned DNA into thermophilic lactobacilli will facilitate the study of heterologous gene expression in non-transformable species.

Cloning, Molecular↗
PubMed1991

Script generation as an indicator of knowledge representation in patients with Alzheimer's disease.

We examined script and lexical retrieval in patients with probable Dementia-Alzheimer's Type (DAT), Depressed patients, and normal controls. DAT patient breakdown in script production was structurally similar to their impaired lexical retrieval such that script events of low frequency and low centrality value were lost first. DAT patients also produced more events that fell outside the script boundary as well as more event-order errors. Four cases with DAT were identified on the basis of Z scores whose script production was at least 2 SDs greater than their lexical production or vice versa. This finding suggests that it may be possible to dissociate script and lexical knowledge and production processes. The findings lend partial support for a model of knowledge representation that includes parallel and partially redundant memory networks that are distinctly distributed in the brain.

Aged↗
PubMed1991

Using a manpower database to model nurse turnaround and return to service.

A manpower database for nurses employed by the Department of Health and Social Services in Northern Ireland has been developed. This database contains information on all nurses employed between March 1977 and July 1988 and consists of data on all posts held in this period, including breaks in service. The authors show how these data may be used to analyse the durations of spells in post and spells out of service prior to departure to a number of destinations for the sister and staff nurse grades. The results are presented in a graphical format which enables us to evaluate the relative proportion of departures to each destination and at what stage in service these departures are likely to occur. Such a methodology provides a valuable tool for the nurse manpower planner, and utilizes personnel data which are routinely collected by most health authorities.

Career Mobility↗
PubMed1991

The Health Knowledge Inventory-Alpha: a personal health knowledge test for high school seniors.

This study assessed validity and reliability of the Health Knowledge Inventory-Alpha (HKI-Alpha) in a sample of high school seniors. The HKI-Alpha, a general health knowledge test, consists of 110 multiple choice items covering 11 health content areas. All seniors attending one of four high schools completed HKI-Alpha twice, one week apart. A secondary sample of college students also was tested. Descriptive analysis revealed the test discriminated among examinees and avoided ceiling and floor effects. Test-retest reliability was .81 (n = 355). Internal consistency reliability (KR20) was .85 (n = 418). A sample of college students scored significantly higher than the high school students, demonstrating construct validity. Other estimates of content validity, criterion-related validity, and construct validity were high.

Adolescent↗
PubMed1991

Rheumatoid factors isolated from patients with autoimmune disorders are derived from germline genes distinct from those encoding the Wa, Po, and Bla cross-reactive idiotypes.

To better understand the structural basis for rheumatoid factor activity, the nucleotide sequence of the light chain variable regions of nine human monospecific IgM rheumatoid factors were analyzed. Rheumatoid factors were isolated from three patients with rheumatoid arthritis, a patient with systemic lupus erythematosus, and a normal individual. The VL gene segments used by these rheumatoid factors are not as restricted as previous work on mixed cryoglobulin rheumatoid factors had suggested. Each of the different VK families is represented and there are two examples where a V lambda gene segment is used. Molecules with structures similar to those of the Wa and Po CRI, characteristic of mixed cryoglobulin rheumatoid factors, are not common among these rheumatoid factors isolated from patients with rheumatoid arthritis. While there are clear examples of rheumatoid factors that are direct copies of germline genes, most of the sequence data suggest that the processes of antigenic selection and somatic mutation contribute significantly to the generation of monospecific rheumatoid factors in patients with autoimmune disease.

Autoimmune Diseases↗
PubMed1991

Calcium-dependent and calcium-independent protease activities in skeletal muscle during sepsis.

Sepsis was produced in rats by implanting into their abdominal cavities fecal pellets containing Escherichia coli (10(2) colony-forming units [CFU]) and Bacteroides fragilis (10(4) CFU). Control rats were implanted with sterile pellets. A febrile response and hyperlactacidemia marked the onset of the septic injury. Control and septic rats were killed 24 and 48 hr after implantations, and posterior leg muscles were removed. Muscles were homogenized to prepare soluble fractions containing calcium-independent lysosomal (cathepsins B and L) and calcium-dependent cytosolic (calpain) proteases. Cathepsin and calpain activities were then assayed using standard procedures. There were no alterations in cathepsins B or L activities during sepsis. Calpain activity in septic muscle was significantly higher than that in control muscles. In vitro calpain sensitivity to Ca2+ was also higher in septic muscle than in controls. The cysteine protease inhibitor leupeptin caused a quantitatively greater inhibition of calpain activity in septic than in control muscles. These data indicate that whereas sepsis has no effect on Ca(2+)-insensitive lysosomal proteases, it is associated with an elevation of the Ca(2+)-dependent cytosolic protease activity.

Animals↗
PubMed1990

Is the copper T 380A device associated with an increased risk of removal due to bleeding and/or pain? An analysis.

Previous studies have consistently shown that the family of the Copper T 380 devices is more effective in preventing accidental pregnancies than the inert, as well as most other, if not all, copper devices. However, a number of these studies also reported a higher removal rate due to bleeding and/or pain for the TCu 380A than for other devices. The programmatical importance of these findings prompted us to analyze the international multi-center randomized clinical trial datasets to examine this question on the new TCu 380A (ParaGard) recently marketed in the U.S. Our results, while confirming the inherent superior efficacy of the TCu 380A, did not reveal a significantly higher removal rate because of bleeding and/or pain among TCu 380A users than among users of the comparative devices, which included the Lippes Loop D, the TCu 200, the TCu 220 and the Multiload Cu 250 devices.

Adolescent↗
PubMed1990

Cytogenetic effects of extremely low doses of plutonium-238 alpha-particle irradiation in CHO K-1 cells.

CHO K-1 cells were irradiated during the G1 phase with 0.5-6 rad of alpha particles. There was no appreciable cell killing in this low dose range. Significantly increased frequencies of sister-chromatid exchanges were induced by doses as low as 0.5 rad of alpha-particle irradiation, whereas increased numbers of chromosomal aberrations were observed following exposure to 2 rad. These results suggest that very low doses of alpha radiation may lead to radiation-induced genetic alterations.

Alpha Particles↗
PubMed1990

Antioxidant-based inhibitors of leukotriene biosynthesis. The discovery of 6-[1-[2-(hydroxymethyl)phenyl]-1-propen-3-yl]-2,3-dihydro-5- benzofuranol, a potent topical antiinflammatory agent.

The leukotrienes, metabolites of arachidonic acid produced through the action of the enzyme 5-lipoxygenase, are important mediators of immediate hypersensitivity and inflammation. Among the variety of diseases in which the leukotrienes may play a symptomatic or causative role is the dermatological condition psoriasis, a chronic proliferative disease of the skin. This study reports the synthesis and comparative biological activities of various ortho-substituted phenols including 4-methoxyphenols, 6-hydroxy-1,2,3,4-tetrahydrobenzopyrans, 2,3-dihydro-5-benzofuranols, and 5-benzofuranols. The phenols prepared in this study were evaluated for their ability to inhibit the production of leukotriene B4(LTB4) in isolated human polymorphonuclear leukocytes (PMNs) and to inhibit a topical inflammatory response in the topical mouse ear (TME) model. In the former case, when the log IC50 was plotted versus the log of the octanol/water partition coefficient (log P), to eliminate the effect of lipophilicity, the 2,3-dihydro-5-benzofuranol ring system was shown to be more potent than the other ring systems examined throughout the range of partition coefficients studied. The ability to inhibit leukotriene production in vitro in human PMNs can be rationalized on the basis of a model that suggests that the observed inhibition is dependent on the kinetic ability of the inhibitor to reduce a radical species and on the fraction of inhibitor that is partitioned into the cell membrane. While the in vivo antiinflammatory activity as measured by the TME did not correlate with the in vitro data, it was felt that the TME represented a valuable measure of the ability of a compound to penetrate the skin to the site of an ongoing inflammatory response. Of the compounds synthesized in this study, 6-[1-[2-(hydroxymethyl)phenyl]-1-propen-3-yl]-2,3-dihydro-5-benzof uranol (1, L-651896) was chosen for further development.

Administration, Topical↗
PubMed1990

Implicit learning in patients with Alzheimer's disease.

We examined implicit memory using priming and procedural learning tasks in patients with probable Dementia-Alzheimer's Type (DAT) to examine whether priming and procedural processes could be dissociated and whether task specificity was a factor in DAT patient performance. Priming was tested using a word recognition paradigm (perceptual priming) and by repeated administrations of a fragmented objects test (long term priming). Procedural learning was tested using repeated and random sequences on a choice serial reaction time task and by repeated administration of a puzzle map of the United States. DAT patients were compared to hospitalized depressed patients, patients suffering from Progressive Supranuclear Palsy (PSP), and normal controls. We found that DAT patients demonstrated marginal but significant implicit learning on both procedural learning and perceptual priming tasks. DAT patients performed relatively better on the procedural learning task than a perceptual priming task compared to PSP patients, suggesting that priming of meaningful stimuli is subserved by cortical structures whereas procedural motor responses to simple serial visual stimulus patterns can be maintained by subcortical systems. Furthermore, our findings suggest that priming and procedural processes can be dissociated and that task specificity is a factor in interpreting the results of implicit learning paradigms in DAT patients. The implications of these results for models of knowledge representation and memory processes as well as the way they can serve as models for testing nootropic drug effects are discussed.

Aged↗
PubMed1990

The complete nucleotide sequences of the heavy chain variable regions of six monospecific rheumatoid factors derived from Epstein-Barr virus-transformed B cells isolated from the synovial tissue of patients with rheumatoid arthritis. Further evidence that some autoantibodies are unmutated copies of germ line genes.

Structural studies of human monoclonal rheumatoid factors (RF) derived from patients with monoclonal gammapathies have revealed a restriction in the usage of heavy and light chain variable regions. These studies have suggested that germline genes with little if any somatic mutation can generate RF specificity. However, there is no information presently available regarding the primary structure and genetic origin of RF in rheumatoid arthritis. In this study, we have isolated and sequenced the VH regions of six monoclonal RF derived from the synovial membranes of two patients with rheumatoid arthritis and one with the juvenile polyarticular form of the disease. We found the same VH families as previously reported among monoclonal paraproteins with RF activity. However, our sample was diverse regarding the VH, DH, and JH gene segments used. Among VHI RF there was conservation in the length of CDRIII as well as restriction in the amino acid generated at the V-D junction, as opposed to VHIII RF and non-RF VHI molecules that are highly heterogeneous in these two aspects. We also found that different JH gene segments may contribute to RF specificity. The VH, DH, and JH elements of one RF in our study all had clearly identifiable germline counterparts. This RF displays a nearly germline configuration throughout its entire heavy chain and represents another example of an autoantibody encoded by one of the VH gene segments from the preimmune fetal repertoire.

Arthritis, Rheumatoid↗
PubMed1990

Cognitive effects of corticosteroids.

In three independent studies with different designs and groups of subjects, the authors found that 1) depressed patients who did not suppress cortisol when given dexamethasone (compared to suppressors and normal control subjects), 2) healthy volunteers given a single 1-mg dose of dexamethasone (compared to those given placebo), and 3) healthy volunteers given 80 mg/day of prednisone for 5 days (compared to those given placebo) all made significantly more errors of commission in verbal memory tasks, with no significant change in their rates of errors of omission. These findings raise the possibility of specific corticosteroid-related cognitive impairments.

Adrenal Cortex Hormones↗
PubMed1990

Cross-sectional echocardiographic characterization of atelectatic lung segments. Differentiation from extracardiac tumors.

This report describes a unique series of patients who, during routine cross-sectional echocardiographic examination, were each noted to have a large echo-dense extracardiac mass adherent to the lateral aspect of the left ventricle. While this echo-dense mass was considered initially to represent an extracardiac tumor, this mass was shown subsequently to be an atelectatic segment of the left lower lobe of the lung. The salient echocardiographic findings that were considered to be helpful in terms of differentiating these adherent pulmonary atelectatic lung segments were that the lung segments always occurred in the presence of a moderate to large left pleural effusion; in real-time examination, the atelectatic lung masses generally appeared solid, as opposed to cystic, with a characteristic brightly reflective ground-glass appearance; there was never any evidence of extrinsic compression of the heart by the lung mass.

Aged↗