Search PubMed⌕ Search

Biomedical subjects

D L Gordon

Publications and source records attributed to D L Gordon.

At least 55 records · Page 3Linked to original sources
PubMed1995

Clinical utility of the polymerase chain reaction to diagnose Mycoplasma pneumoniae infection.

The diagnosis of Mycoplasma pneumoniae infection currently relies on serological methods which may be slow to produce diagnostic results and may be inconvenient for both the clinician and the patient. This study was designed to assess whether or not the polymerase chain reaction (PCR) is a useful additional diagnostic method. Comparison was therefore made with serology as it is routinely practiced. PCR was used to examine for the presence of M. pneumoniae DNA in throat swab specimens obtained from 99 hospitalized patients investigated for a range of respiratory pathogens including M. pneumoniae. PCR detected M. pneumoniae DNA in 24 adults and 25 children, which is significantly more than the 32 patients found to be antibody positive by the particle agglutination test (p = 0.001). M. pneumoniae DNA was not detected in any of the throat swabs from 32 apparently healthy volunteers. PCR inhibitors were not detected in any of the samples tested. Significantly more children (88%) than adults (38%) were found to be anti-mycoplasma antibody-positive (p < 0.0001). Routine clinical practice was reflected in the fact that 56 patients (57%) had indeterminate serological results because only single sera were obtained. The sensitivity and specificity of PCR were assessed to be 92% and 98% respectively, using a combination of serological and clinical data as the benchmark. PCR appears to have advantages over serological testing, both with respect to accuracy and convenience of single specimen testing. The poor performance of serological tests in adults makes PCR especially useful in this age group.

Adult↗
PubMed1995

Enhancement of NK cell-mediated antibody-dependent lysis of recombinant gp120-coated CD4 cells by complement.

The contribution of complement to NK cell lysis of CD4 cells expressing recombinant gp120 (rgp120) was investigated. Peripheral blood mononuclear cells were used as effector cells in a Cr release assay against purified CD4 target cells that had been coated with rgp120. Assays included human immunodeficiency virus (HIV) antibodies and a complement source alone and in combination to determine their importance in mediating cytotoxicity. NK cells were confirmed to be the effector cells in the lysis of rgp120-coated CD4 targets. Anti-HIV was crucial for lysis and cytotoxicity was enhanced by C3 deposition on targets. However, a prozone effect was observed, with reduced IgG binding, C3 deposition, and NK cell lysis at serum concentrations > 10 micrograms IgG/mL. The susceptibility of these CD4-gp120-antibody-C3 complexes to NK cell lysis may contribute to progressive depletion of CD4 cells in HIV infection.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1995

Chest wall actinomycosis in association with the use of an intra-uterine device.

A 31 year old woman presented with a chest wall abscess due to Actinomyces israellii and Porphyromonas asaccharolytica (previously Bacteroides asaccharolyticus). She was a long-term user of an intra-uterine device (IUD) and, although asymptomatic, had radiological evidence of pelvic infection. Actinomyces-like organisms were seen on cervico-vaginal smears. The abscess was surgically drained, the IUD removed, and a prolonged course of amoxycillin/clavulanic acid given.

Actinomyces↗
PubMed1994

Upregulation of human neutrophil CD59, a regulator of the membrane attack complex of complement, following cell activation.

CD59 is a membrane glycoprotein that regulates the membrane attack complex of complement and protects cells from autologous complement damage. Human polymorphonuclear leucocyte (PMN) expression of CD59 was confirmed by flow cytometry following staining with mAb 1F5, and western blotting revealed staining of a 19-23 kDa band. Warming of PMN from 4 to 37 degrees C resulted in spontaneous CD59 upregulation. A dose-dependent increase in expression following PMN stimulation with FMLP was observed and occurred within minutes, indicating that new protein synthesis was not required. Treatment of PMN with calcium ionophore A23187 resulted in similar increases in CD59 expression. This occurred in the presence or absence of extracellular calcium, indicating that upregulation was dependent on release of calcium from intracellular stores. Evidence for a mobilizable intracellular pool of CD59 was obtained by detection of increased binding of 1F5 following PMN permeabilization; CD59 could also be re-expressed after stripping by phosphatidylinositol specific phospholipase C (PI-PLC) by treatment with FMLP or A23187. There was a correlation between CD59 upregulation and lactoferrin release, suggesting that stores of CD59 may be associated with secondary granules. These studies indicate that PMN expression of CD59 is enhanced by cell activation and suggest the presence of an intracellular pool of CD59 which can be translocated to the cell membrane upon PMN stimulation.

Antibodies, Monoclonal↗
PubMed1994

Regulation of C3 deposition on gp120 coated CD4 positive cells by decay accelerating factor and factor H.

We investigated complement activation by recombinant gp120 (rgp120) treated CD4 cells and the role host complement regulatory proteins play in controlling C3 deposition. Complement activation was determined by detection of C3 on rgp120 coated cells in the presence and absence of HIV seropositive sera using flow cytometry. Treatment of rgp120 coated cells with complement resulted in C3 deposition only if HIV positive sera was included. Examination of C3 fragments on these cells demonstrated rapid cleavage of C3b to iC3b. The role of the regulatory proteins was examined by pretreating cells with mAb to block decay accelerating factor (DAF) or membrane cofactor protein (MCP) or by using factor H depleted sera as a complement source. Inhibition of DAF or use of factor H depleted sera significantly increased C3 deposition on rgp120 coated cells. In contrast, C3 deposition on rgp120 coated cells was not increased after blocking MCP. The sensitivity of rgp120 coated cells to complement lysis was unchanged after inhibition of the regulatory proteins, despite the increase in C3 deposited. These results indicate that in a model of virus infected cells, C3 deposition is regulated by DAF and factor H but MCP appears to have no role.

Antigens, CD↗
PubMed1994

Cystic pulmonary lesions in Pneumocystis carinii infection.

Thick-walled pulmonary cavities are an uncommon manifestation of Pneumocystis carinii pneumonia (PCP). A case of PCP in a man with Acquired Immunodeficiency Syndrome (AIDS) presenting with a thick-walled pulmonary cavity and multiple smaller pulmonary air cysts is described. All of these lesions showed dramatic healing with therapy. A brief review of the recent literature is also presented.

AIDS-Related Opportunistic Infections↗
PubMed1994

The impact of unit-based self-management by nurses on patient outcomes.

OBJECTIVE: Patients discharged from a self-managed nursing unit are compared with patients from traditionally managed units on postdischarge outcomes. DATA SOURCES AND STUDY SETTING: Primary data were collected on patients discharged from eight nursing units in three clinical areas in one hospital from August through November 1990. STUDY DESIGN: A case series of eligible patients discharged from four self-managed nursing units (n = 140) are compared with patients from four matched traditionally managed units (n = 138) on postdischarge outcomes: perceived health status, perceived functional status, needs for care, unmet needs for care, unplanned health care visits, and readmissions to the hospital within 31 days of discharge. DATA COLLECTION METHODS: Patients were interviewed by telephone at approximately two weeks postdischarge, and data from hospital records were merged with interview data. PRINCIPAL FINDINGS: Bivariate and multiple logistic regression analyses showed no significant effects (either positive or negative) of self-managed units on the postdischarge outcomes studied. CONCLUSIONS: Self-managed nursing units, previously shown to improve nurses' work satisfaction and retention, have no impact on patient postdischarge outcomes.

Adolescent↗
PubMed1993

Common epitope on HIV p24 and human platelets.

Mimicry of human antigen by HIV may underlie the autoreactivity seen in AIDS. A mouse monoclonal antibody (VIC8) raised against HIV p24 cross-reacted with human platelets; binding could be abolished by recombinant p24 antigen. VIC8 bound less well to platelets from patients with HIV than to those from healthy individuals. In the HIV group, binding was not related to p24 antigenaemia, disease stage, or platelet counts. This cross-reactivity is another example of antigenic mimicry by HIV and may be mechanistically important in HIV-associated autoimmune-like thrombocytopenia.

Antibodies, Monoclonal↗
PubMed1993

Characterization of factor H binding to human polymorphonuclear leukocytes.

Previous studies indicate that factor H (fH) binds to a number of cell types and may have functions other than C regulation. We have examined for fH binding to PMN using flow cytometry and radiolabeled binding assays. Binding of fH was demonstrated to be specific and saturable with approximately 6 x 10(4) binding sites/polymorphonuclear leukocytes (PMN) and a Ka value of 3.3 x 10(8) L/M. Binding of fH to PMN was ionic strength dependent, required divalent cations, and was enhanced by PMN stimulation with FMLP and calcium ionophore, A23187. The 38-kDa N-terminal tryptic fragment of fH bound to PMN and blocking experiments with mAb suggested a receptor binding site was located within the fifth SCR of fH. fH binding was not due to associations with surface-bound C3 or to CR3. Binding of fH to U937 and Raji cells, but not to T cells was also demonstrated. These studies provide presumptive evidence for a fHR on PMN. Binding of fH by fHR could enhance recognition of opsonized targets, trigger secondary intracellular events or contribute to intrinsic protection of cells against C.

Amino Acid Sequence↗
PubMed1993

Expression of CD59, a regulator of the membrane attack complex of complement, on human astrocytes.

The present study demonstrates that human astrocytes synthesize and express CD59, a regulator of the membrane attack complex of complement. This was shown by flow cytometry following staining of astrocytes with MAb to CD59, and Western blotting of astrocyte lysates, which revealed the characteristic 18-23,000 M(r) band of CD59. Synthesis of CD59 by astrocytes was confirmed by detection of CD59 specific mRNA by polymerase chain reaction. A low level of C3 deposition occurred on astrocytes following exposure to autologous serum. CD59 may prevent subsequent damage from C5b-9 and protect astrocytes during inflammatory and infectious disorders of the nervous system.

Antigens, CD↗
PubMed1993

Effect of needle changing and intravenous cannula collection on blood culture contamination rates.

STUDY OBJECTIVES: We tested the hypotheses that blood culture positivity and contamination rates were not increased by not changing needles between venipuncture and inoculation of blood culture bottles or by taking blood for culture by freshly inserted IV cannulae. DESIGN: A prospective study of blood cultures collected by venipuncture or IV cannulae taken from an emergency department population. Venipuncture samples were randomized into needle change (standard method) or no needle change before inoculation into blood culture bottles. PARTICIPANTS: Nine hundred forty patients requiring blood cultures after assessment in the ED. INTERVENTIONS: A standard disinfection procedure using 0.5% chlorhexidine in 70% alcohol was used. Blood was collected by venipuncture and inoculated with or without needle change. Blood collected by IV cannula was inoculated with a fresh needle applied to the collection syringe. MEASUREMENTS AND MAIN RESULTS: There was no statistically significant difference in contamination rates for blood collected by venipuncture with no needle change (6.4%) compared with needle change (4.2%, P > .30). No significant difference in contamination rates was noted for blood taken by freshly inserted IV cannulae (4.3%) compared with venipuncture with needle change after sampling (4.2%, P > .90). Some problems with randomization resulted in unequal numbers in the needle-change (286) versus no-needle-change (141) subgroups, and this may have introduced bias. A higher rate of pathogen growth was observed in blood taken by IV cannula (11.4%) compared with the standard method (6.3%) (P < .025). A significantly greater rate of Gram-negative sepsis was noted in the IV cannula group (6.6%) compared with direct venipuncture with needle change (1.1%) and no needle change (4.2%, P < .01). CONCLUSION: The results of this study do not support the practice of changing needles before inoculating blood samples into blood culture bottles. Collection of blood for culture through freshly inserted IV cannulae is associated with a low contamination rate and is an acceptable alternative to direct venipuncture. Sources of bias in this study suggest that further research is needed to determine the optimal technique for collecting blood cultures.

Bacteriological Techniques↗
PubMed1993

Detection of mosaic protein mRNA in human astrocytes.

Mosaic proteins consist of a group of proteins that may be comprised of one or more types of a variety of different structural modules and have a diverse range of functions. We have examined primary human astrocyte cultures for the presence of three mosaic proteins, B2I and the complement proteins factor H and properdin. Using the polymerase chain reaction and an enhanced chemiluminescence detection technique, we were able to show that mRNA transcripts for each of these proteins are expressed in human astrocytes.

Astrocytes↗
PubMed1993

The effect of fine-needle aspiration biopsy on the thyroid scan.

Fine-needle aspiration biopsy (FNAB) is the most sensitive and specific procedure in diagnosing benign from malignant thyroid nodular disease. The effects of a FNAB on the thyroid scan, however, have never been studied. This assumes importance because a hot nodule on scan has been advocated as useful to differentiate certain benign from malignant follicular neoplasms. Thyroid scans were performed before and after FNAB on 11 patients with nodular thyroid disease and an area of normal or increased uptake either in the nodule or in a contralateral enlarged lobe to determine if the biopsy changed the pattern of isotope uptake. For this study, biopsies were done in the area of normal or increased uptake. In two patients, there was a reduction in isotope concentration in three nodules after FNAB, whereas no change was demonstrable in nine other patients. Review of the literature revealed a number of prior reports of hemorrhage, necrosis, or infarction of thyroid nodules after FNAB. Based on these data and the demonstration of a change in scan pattern in a patient following FNAB, it is concluded that FNAB may decrease the isotope uptake in thyroid nodules; therefore, the concept of clinical judgments being based on the scan pattern after FNAB should be reevaluated.

Adult↗
PubMed1993

The effects of unit self-management on hospital nurses' work process, work satisfaction, and retention.

A number of innovative practice models have been introduced in an effort to resolve the hospital nursing shortage and improve the working conditions and retention of registered nurses. This study examines the effects of a unit-level self-management model (including salaried compensation and gainsharing) in a number of clinical areas at The Johns Hopkins Hospital in Baltimore, Maryland. In comparisons of nurses on self-managed and traditional nursing units, outcomes examined were nurses' perceptions of their work process, nurses' work satisfaction levels, and nurses' retention. The self-management model is found to increase work satisfaction through effects on two work process variables: coordination of care and effective team performance. The model is also associated with higher retention. Nurses on self-managed units work longer hours but earn increased pay; the effects of hours and pay on work satisfaction and retention are discussed.

Baltimore↗
PubMed1993

Classification of subtype of acute ischemic stroke. Definitions for use in a multicenter clinical trial. TOAST. Trial of Org 10172 in Acute Stroke Treatment.

BACKGROUND AND PURPOSE: The etiology of ischemic stroke affects prognosis, outcome, and management. Trials of therapies for patients with acute stroke should include measurements of responses as influenced by subtype of ischemic stroke. A system for categorization of subtypes of ischemic stroke mainly based on etiology has been developed for the Trial of Org 10172 in Acute Stroke Treatment (TOAST). METHODS: A classification of subtypes was prepared using clinical features and the results of ancillary diagnostic studies. "Possible" and "probable" diagnoses can be made based on the physician's certainty of diagnosis. The usefulness and interrater agreement of the classification were tested by two neurologists who had not participated in the writing of the criteria. The neurologists independently used the TOAST classification system in their bedside evaluation of 20 patients, first based only on clinical features and then after reviewing the results of diagnostic tests. RESULTS: The TOAST classification denotes five subtypes of ischemic stroke: 1) large-artery atherosclerosis, 2) cardioembolism, 3) small-vessel occlusion, 4) stroke of other determined etiology, and 5) stroke of undetermined etiology. Using this rating system, interphysician agreement was very high. The two physicians disagreed in only one patient. They were both able to reach a specific etiologic diagnosis in 11 patients, whereas the cause of stroke was not determined in nine. CONCLUSIONS: The TOAST stroke subtype classification system is easy to use and has good interobserver agreement. This system should allow investigators to report responses to treatment among important subgroups of patients with ischemic stroke. Clinical trials testing treatments for acute ischemic stroke should include similar methods to diagnose subtypes of stroke.

Anticoagulants↗
PubMed1993

Interphysician agreement in the diagnosis of subtypes of acute ischemic stroke: implications for clinical trials. The TOAST Investigators.

To test interphysician agreement on the diagnosis of subtype of ischemic stroke, we sent subtype definitions and 18 case summaries (clinical features and pertinent laboratory data) to 24 neurologists who have a special interest in stroke, and asked them to determine the most likely subtype diagnosis. The overall agreement was 0.64 (Kappa [K] = 0.54). Interphysician agreement was highest for the diagnoses of stroke secondary to cardioembolism (K = 0.75) or to large-artery atherosclerosis (K = 0.69). Individual physicians varied widely; four agreed with the consensus diagnosis in all 18 cases, while six others disagreed with the consensus diagnosis in three to five cases. Our level of interphysician agreement is greater than that reported in other studies and was substantial. However, despite using subtype definitions and being given extensive information often not available in the acute setting, physicians still disagree about the etiology of stroke, particularly in regard to stroke due to small-artery occlusion or of undetermined etiology. Physicians seem reluctant not to attribute stroke to a specific etiology. The uncertainty about subtype diagnosis will affect interpretation of the results of clinical trials in patients selected by the subtype of ischemic stroke and also suggests that results of treatment as affected by subtype should be cautiously interpreted unless efforts to assure uniformity are included in the trial's operations. Refinement of algorithms for determining subtype of ischemic stroke do improve interphysician agreement. Such criteria should be applied strictly, and trials should include measures to assure the most uniform diagnosis of stroke subtype possible.

Aged↗