Segmentation of elemental EDS maps by means of multiple clustering combined with phase identification.

An imaging concept is proposed for the phase identification and segmentation of elemental map images from energy dispersive spectroscopy. The procedure starts with presegmentation using common clustering algorithms, continues with automated identification of the chemical compositions, followed by their screening by professional expertise. The ultimate phases are finally clustered by applying a minimum Euclidean distance classifier. The potential, performance and limitations of the approach are presented on energy dispersive spectroscopy maps acquired by a scanning electron microscope and conducted on samples produced from cement clinker, natural rock and hydrated cement mortar. Nevertheless, the technique is suitable for arbitrary types of materials and general devices for energy dispersive spectroscopy acquisition. It is an approach for extending common energy dispersive spectroscopy analysis by means of visual examination and ratio plots towards quantitative rating.

Myocardial infarction with minimal coronary atherosclerosis in the era of thrombolytic reperfusion. The Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) Study Group.

The incidence of minimal residual atherosclerotic coronary obstruction after successful intravenous thrombolytic therapy was evaluated in 799 patients with acute myocardial infarction. Minimal residual coronary obstruction (less than or equal to 50%) was observed on selective coronary angiography performed 90 min after initiation of thrombolytic therapy in 43 patients (5.5%). In 42 other patients (5.4%), a greater than 50% but less than 100% residual stenosis noted at 90 min demonstrated further resolution of obstruction to less than 50% at an angiographic follow-up study 7 to 10 days later. Patients with minimal residual coronary obstruction were significantly younger (52 +/- 10.7 versus 56.7 +/- 10 years; p = 0.002) and had less multivessel coronary disease (p less than 0.001), better initial left ventricular ejection fraction (54 +/- 12% versus 50.2 +/- 11.4%; p = 0.006) and a lower in-hospital mortality rate (1% versus 7%; p = 0.04) than did patients who had a significant (greater than 50%) residual coronary obstruction after intravenous thrombolysis. Long-term follow-up study of patients with a minimal coronary lesion (average 1.5 +/- 0.6 years) and those with significant residual stenosis (average 1.6 +/- 0.7 years) demonstrated that the incidence of death (2.4% in patients with minimal stenosis versus 3.5% in those with significant stenosis) and recurrent myocardial infarction (5% each) were similar in both groups. New strategies are needed to prevent coronary rethrombosis in patients with minimal atherosclerosis after thrombolytic therapy for acute myocardial infarction.

Emergency coronary artery bypass surgery preserves global and regional left ventricular function after intravenous tissue plasminogen activator therapy for acute myocardial infarction.

Emergency coronary bypass surgery was performed in 24 (6.2%) of 386 consecutive patients enrolled in the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) Multicenter Trial. Intravenous tissue plasminogen activator was administered 2.6 +/- 0.7 h and bypass surgery was performed 7.3 +/- 1.9 h after the onset of infarction. Infarct artery patency was achieved in 21 (88%) of the 24 patients (pharmacologically in 18 or mechanically with coronary angioplasty in 3) in the catheterization laboratory before bypass surgery. The indication for surgery was left main or equivalent coronary artery disease in 7 patients, coronary anatomy unsuitable for angioplasty in 4 patients and unsuccessful coronary angioplasty in 13 patients. A coronary perfusion catheter was inserted before surgery in 11 of 13 patients with unsuccessful angioplasty. All three deaths occurred postoperatively in patients with preoperative cardiogenic shock. Three patients required surgical reexploration for postoperative hemorrhage. Comparison of preoperative and predischarge contrast left ventriculograms demonstrated significant preservation of global (left ventricular ejection fraction 49 +/- 6 to 56 +/- 6%; p = 0.008) and regional (standard deviation/chord -2.6 +/- 0.5 to -1.5 +/- 1.1; p = 0.001) left ventricular function. Emergency coronary bypass surgery can be performed with a low morbidity and mortality in patients treated with intravenous tissue plasminogen activator therapy for acute myocardial infarction. Such therapy is associated with significant preservation of global and regional (infarct zone) left ventricular function.

Detection of CD1 mRNA in Paneth cells of the mouse intestine by in situ hybridization.

Cluster of differentiation 1 (CD1) antigens are a family of non-MHC but Class I-like molecules that have been identified in humans and rodents. Although their function(s) remains unknown, it has been proposed that CD1 may present antigens to specific subsets of peripheral T-cells. We now provide evidence in support of this hypothesis through the demonstration by in situ hybridization that Paneth cells of the mouse intestine express CD1 mRNA. These cells are thought to be involved in the immunological regulation of intestinal flora and could accomplish this task through interactions with intestinal intraepithelial lymphocytes. The expression and localization of CD1 mRNA was confirmed by both autoradiographic and non-isotopic techniques. The relevance of these results to CD1 function as well as to Paneth cell biology is discussed.

Implementation of a thrombolytic protocol in the emergency department.

The emergency department plays a pivotal role in the identification, selection, and treatment of candidates for thrombolytic therapy. Organized treatment protocols offer direction to the emergency staff and enhance their efficiency and success. However, the process of drug administration is not a one person job. It requires the efforts of a "support team," all of whom must be educated regarding protocol goals and expectations. With the creation of special tools, implementation becomes an achievable task, and staff demands are reduced proportionately. As patient outcomes are known, it is essential to pass these data on to all team members. There is no greater payback for a dedicated caregiver than to realize his positive impact on patient outcome.

Induced thermotolerance to apoptosis in a human T lymphocyte cell line.

A brief exposure to elevated temperatures elicits, in all organisms, a transient state of increased heat resistance known as thermotolerance. The mechanism for this thermotolerant state is unknown primarily because it is not clear how mild hyperthermia leads to cell death. The realization that cell death can occur through an active process of self destruction, known as apoptosis, led us to consider whether thermotolerance provides protection against this mode of cell death. Apoptosis is a common and essential form of cell death that occurs under both physiological and pathological conditions. This mode of cell death requires the active participation of the dying cell and in this way differs mechanistically from the alternative mode of cell death, necrosis. Here we show that mild hyperthermia induces apoptosis in a human leukemic T cell line. This is evidenced by chromatin condensation, nuclear fragmentation and the cleavage of DNA into oligonucleosome size units. DNA fragmentation is a biochemical hallmark of apoptosis and requires the activation of an endogenous endonuclease. The extent of DNA fragmentation was proportional to the severity of heat stress for cells heated at 43 degrees C from 30 to 90 minutes. A brief conditioning heat treatment induced a resistance to apoptosis. This was evident as a resistance to DNA fragmentation and a reduction in the number of apoptotic cells after a heat challenge. Resistance to DNA fragmentation developed during a recovery period at 37 degrees C and was correlated with enhanced heat shock protein (hsp) synthesis. This heat-induced resistance to apoptosis suggests that thermotolerant cells have gained the capacity to prevent the onset of this pathway of self-destruction. An examination of this process in heated cells should provide new insights into the molecular basis of cellular thermotolerance.

Biochemical and developmental characterization of the murine cluster of differentiation 1 antigen.

The cluster of differentiation-1 (CD1) antigens are major histocompatibility complex (MHC) class I-like glycoproteins belonging to the immunoglobulin supergene family. Initially described in humans, more recently putative CD1 encoding genes have been identified in several other species, including the mouse where it has been clearly demonstrated that CD1 mRNA is expressed. However, in the mouse both its unusually wide tissue distribution and the prevalence of incompletely spliced RNA have raised the possibility that the mRNA did not encode a functional protein. We have utilized a rabbit polyclonal antiserum raised against an Escherichia coli-expressed recombinant murine CD1 fusion protein to characterize the murine CD1 protein. Here we demonstrate that the antiserum binds specifically to a set of glycoproteins (49,000-55,000 MW) which contain a common core protein with both a size (36,000 MW) and tissue distribution in accordance with those predicted. During thymic ontogeny, this protein is highly expressed by Day 14 of embryonic development and persists into adulthood, while its pattern of expression in other organs changes significantly during development. Thus, the mouse provides an amenable model system for the study of CD1 function.

Isolation of CD1 genes: a family of major histocompatibility complex-related differentiation antigens.

CD1 differentiation antigens are defined by a group of monoclonal antibodies that characterize immature human thymocytes. A cloned cDNA has been used to identify CD1 genes in a human genomic library. Five CD1 genes have been isolated, and Southern blot analysis suggests that these represent all the cross-hybridizing human CD1 genes. They share a highly conserved exon, which is homologous to the beta 2-microglobulin-binding domain (alpha 3) of major histocompatibility complex (MHC) class I antigens. In this domain, amino acid sequences are 71-88% homologous. However, the homology between CD1 and MHC class I alpha 3 domains is only 21%. This is the same degree of homology as between either of them and the class II beta 2 domain, which does not bind beta 2-microglobulin. The evolutionary implications of these results are discussed.

DNA synthesis during growth and synchronous differentiation of Naegleria.

Naegleria gruberi amoebae were stimulated to differentiate synchronously into flagellates under growth conditions by lowering the temperature from 32 degrees C to 20.5 degrees C. In the presence of nutrient medium, flagellates will eventually revert to amoebae and resume growth. The time course of nuclear DNA synthesis, using a double thymidine isotope procedure, was determined for: (1) logarithmically growing amoebae, (2) differentiating cells, and (3) flagellates that were reverting to amoebae. DNA replication ceased 10 min. after the stimulation of differentiation, and began again during reversion. Neither de novo transcription nor translation appear to be required for the cessation of DNA replication during differentiation.

Ascaris lumbricoides: characterization of the collagenous components of the adult cuticle.

The proteins of the cuticle of adult Ascaris lumbricoides suum were characterized with respect to heterogeneity, glycosylation, and susceptibility to collagenase. Pepsin digestion of intact cuticles was used to determine the extent of stable triple-helical structures of the cuticular components. With sodium dodecyl sulfate-poly-acrylamide gel electrophoresis, it was shown that treatment of purified cuticles with beta-mercaptoethanol released three components (99, 90, and 68 kDa) which comprise 95% of the total solubilized material. The remaining fraction consists of at least four components (16, 28, 154, and 173 kDa). Periodic acid-Schiff staining showed that the only glycoprotein was the 173-kDa component. All cuticular components, except the 173-kDa protein, were degraded by bacterial collagenase. Pepsin digestion of intact cuticles for 24 hr at 4 C produced, after reduction, a 95-kDa fragment; by 96 hr, four fragments (95, 90, 83, and 77 kDa) were evident. When the 96-hr pepsin digest was treated with fresh pepsin, the 77-kDa fragment became the major constituent. With agarose gel electrophoresis, analysis of non-reduced, pepsin-released material revealed intact aggregates that were greater than 2 X 10(3) kDa. The enzyme digestion studies indicate that, with the exception of the 173-kDa component, each cuticular protein contains collagenous domains and that, within the cuticle, the longest contiguous collagen chain in a triple-helical conformation has a uniform molecular size of 77 kDa.

Structure and expression of the human thymocyte antigens CD1a, CD1b, and CD1c.

The CD1 human antigens are a family of at least three components, CD1a, CD1b, and CD1c, that are characteristic of the cortical stage of thymocyte maturation. CD1a was originally named HTA1 or T6 and thought to be the human equivalent of mouse Tla. The genes coding for all three have now been identified by transfection into mouse cells. The transfectants express the surface antigens that can then be recognized by the corresponding cluster of monoclonal antibodies used to define the three members of CD1. The full sequence of the genomic DNA is described for all three. The intron-exon structure of CD1a is deduced by comparison with a near-full-length cDNA clone. Similar structures are proposed for the other two, largely based on sequence homology. An unusually long 5'-untranslated exon (280 bases long) is highly conserved between the three genes, suggesting an important but unknown function. CD1c has a duplicated form of this exon that is thought to be spliced out. The major homology between the three antigens is in the beta 2-microglobulin-binding domain. The general relatedness to major histocompatibility complex class I and class II molecules is significant but low, with no section of higher homology to mouse Tla.

Changes in heat shock protein synthesis and heat sensitivity during mouse thymocyte development.

Heat shock protein synthesis was examined in mouse thymocytes at three stages of development: early embryonic thymocytes, which are CD4-CD8-, adult thymocytes, which are primarily CD4+CD8+, and mature spleen T cells, which are CD4+CD8- or CD4-CD8+. After either a 41 degrees C or 42 degrees C heat shock, the synthesis of the major heat-inducible protein (hsp68) was elevated during the first hour of recovery but then decreased abruptly in thymocytes from adult mice. In contrast, the synthesis of hsp68 continued for up to 4 h after heating embryonic mouse thymocytes or mature spleen T cells. The more rapid termination of the heat shock response in the adult thymocytes was not the result of either less heat damage or more rapid repair since the recovery of general protein synthesis was more severely delayed in these cells. As well, the double positive CD4+CD8+ cells were more sensitive to hyperthermia than either the double negative CD4-CD8- or single positive CD4+CD8- or CD4-CD8+ cells. Exposure of fetal thymus organ cultures to elevated temperature revealed that the double negative thymocytes were able to survive and differentiate normally following a heat shock treatment that was lethal for the double positive thymocytes. Exposure of thymocytes from adult mice to elevated temperatures induced apoptotic cell death. This was evident by the cleavage of DNA into oligonucleosome-sized fragments. Quantitation of the extent of DNA fragmentation and the number of apoptotic cells by flow cytometry demonstrated that the extent of apoptotic cell death was related to the severity of the heat stress. Double positive (CD4+CD8+) thymocytes are selected on the basis of their T-cell antigen receptor (TCR). Most of these cells are negatively selected and die within the thymus by an active process of cell deletion known as apoptosis. Restricting hsp synthesis in response to stress might be essential during developmental processes in which cell maturation is likely to result in death rather than functional differentiation.

Relative importance of emergency medical system transport and the prehospital electrocardiogram on reducing hospital time delay to therapy for acute myocardial infarction: a preliminary report from the Cincinnati Heart Project.

Substantial time delays from symptom onset to diagnosis and treatment of patients with acute myocardial infarction have been demonstrated. To determine the relative importance of prehospital mode of patient transport and the relative impact of emergency medical system transport with or without a prehospital cellular electrocardiogram (ECG) on hospital time delays to initiation of thrombolytic therapy, four prospective parallel groups of patients with acute myocardial infarction were evaluated. The median hospital time delay to treatment median (twenty-fifth and seventy-fifth percentiles) was 64 minutes (46 and 87 minutes, respectively, for twenty-fifth and seventy-fifth percentiles) for patients transported by private automobile ("walk-in"); 55 minutes (45 and 68 minutes, respectively) for patients transported by local ambulance; 50 minutes (38 and 81 minutes, respectively) for patients transported by the emergency medical system without a prehospital ECG; and 30 minutes (27 and 35 minutes, respectively) for patients transported by the emergency medical system who had a 12-lead ECG transmitted from the field. Patients transported by the emergency medical system were randomized to receive cellular telephone transmission of a prehospital 12-lead ECG. Specialized emergency medical system transport alone did not facilitate in-hospital initiation of thrombolytic therapy in patients with acute myocardial infarction when compared with those brought by local ambulance or by private automobile. A significant reduction in hospital time delay to treatment was observed only in patients transported by the emergency medical system who had cellular transmission of a prehospital 12-lead ECG from the field.

Coronary bypass surgery improves global and regional left ventricular function following thrombolytic therapy for acute myocardial infarction. TAMI Study Group.

Coronary bypass surgery was performed prior to hospital discharge in 303 (22%) of 1387 consecutive patients enrolled in the TAMI 1 to 3 and 5 trials of intravenous thrombolytic therapy for acute myocardial infarction. Bypass surgery was of emergency nature (less than 24 hours from treatment with intravenous thrombolytic therapy) in 36 (2.6%) and was deferred (greater than 24 hours) in 267 (19.3%) patients. The indications for bypass surgery included failed angioplasty (12%); left main or equivalent coronary disease (9%); complex or multivessel coronary disease (62%); recurrent postinfarction angina (13%); and refractory pump dysfunction, mitral regurgitation, ventricular septal rupture or abnormal predischarge functional test (1% each). Although patients having bypass surgery were older (59.5 +/- 9.8 versus 56.0 +/- 10.2 years, (p less than 0.0001), had more extensive coronary artery disease (46% with three-vessel disease versus 11%, (p less than 0.0001), had more frequent diabetes mellitus (19% versus 15%, (p = 0.048), had more prior infarctions (p less than 0.0001), had more severe initial depression in global left ventricular ejection fraction (48.0 +/- 11.9% versus 51.8 +/- 11.9%, p = 0.0002), and regional infarct zone (-2.7 +/- 0.94 versus -2.5 +/- 1.1 SD/chord, p = 0.02) and noninfarct zone function (-0.36 +/- 1.8 versus 0.43 +/- 1.6 SD/chord, p less than 0.0001) than patients not having coronary bypass surgery, no difference in the incidence of death in hospital (7% surgical versus 6% nonsurgical) or death at long-term follow-up of hospital survivors (7% surgical versus 6% nonsurgical) was noted between groups. Surgical patients demonstrated a greater degree of recovery in left ventricular ejection fraction (3.4 +/- 9.8% versus 0.16 +/- 8.5%, p = 0.036) and infarct zone regional function (0.71 +/- 1.1 versus 0.34 +/- 0.99 SD/chord, p = 0.001) when immediate (90 minutes following initiation of thrombolytic therapy) and predischarge (7 to 14 days after treatment) contrast left ventriculograms were compared than did patients who received only intravenous thrombolytic therapy with or without coronary angioplasty. These data suggest a beneficial influence of coronary bypass surgery on left ventricular function and possibly on the clinical outcome of patients initially treated with intravenous thrombolytic therapy for acute myocardial infarction.

Antiserums for immunofluorescent enumeration of human T lymphocytes utilizing fluoresceinated staphylococcal protein A.

Five lots (100 ml or more) of heterologous antiserums specific for human T lymphocytes were prepared using human or Rhesus monkey thymocytes as immunogens. After appropriate adsorptions, these antiserums reacted by immunofluorescence with 68% of human peripheral blood mononuclear cells and 98% of human thymocytes, with E-rosette--positive cells but not with EAC-rosette--positive cells or five human B-lymphoblastoid-cell lines. Blocking experiments showed that Rhesus monkey thymocytes share thymic antigenic determinant(s) with humans. E-rosette receptors modulated independently from T-cell heteroantigens. Non-E--rosetting neoplastic T cells were identified in several patients with lymphoproliferative malignancies. Applying both the E-rosette assay and the anti-T-cell serum provides a better method of defining the biologic properties of normal and neoplastic T lymphocytes. Standardization of immunofluorescent conjugates for human T- or B-cell enumeration is simplified if large lots of well-characterized antiserums are available.

Sustained platelet glycoprotein IIb/IIIa blockade with oral xemilofiban in 170 patients after coronary stent deployment.

BACKGROUND: Inhibition of platelet aggregation with parenteral glycoprotein (GP) IIb/IIIa receptor blockers can reduce the ischemic complications of angioplasty. Sustained efficacy and safety of protracted GP IIb/IIIa blockade with an orally administered agent have not previously been determined. This study is the first randomized, dose-ranging, single-blind, placebo-controlled trial of xemilofiban, an oral platelet GP IIb/IIIa receptor antagonist, administered to patients after intracoronary stent deployment. The pharmacodynamic efficacy of xemilofiban-induced platelet inhibition and clinical safety of this agent was evaluated during chronic therapy. METHODS AND RESULTS: After elective intracoronary stent deployment, patients were randomized to receive placebo (250 mg ticlopidine P.O. BID) or xemilofiban in doses of 5, 10, 15, or 20 mg P.O. BID. All patients received 325 mg aspirin P.O. QD. Inhibition of ex vivo platelet aggregation in response to 20 micromol/L ADP and 4 microg/mL collagen was measured over time after the initial dose of study drug and at 1 and 2 weeks of chronic therapy. Study drug was discontinued after 2 weeks, and all patients were followed clinically for > or = 30 days. Oral xemilofiban resulted in a dose-dependent inhibition of platelet aggregation in response to both agonists that was sustained through 2 weeks of chronic therapy. Doses of xemilofiban required to achieve > or = 50% inhibition of platelet aggregation were > or = 10 mg, and the duration of inhibition was 8 to 10 hours. No significant hemorrhagic episodes or blood transfusions were observed in this trial. CONCLUSIONS: Oral xemilofiban in doses of > or = 10 mg produced > or = 50% inhibition of platelet aggregation in response to ADP and collagen for 8 to 10 hours after dosing. Platelet inhibition was sustained through 2 weeks of chronic therapy. The optimal duration of oral GP IIb/IIIa blockade to effectively suppress recurrent ischemic events after coronary intervention remains to be determined.

Time delays in the diagnosis and treatment of acute myocardial infarction: a tale of eight cities. Report from the Pre-hospital Study Group and the Cincinnati Heart Project.

To establish the magnitude of prehospital and hospital delays in initiating thrombolytic therapy for acute myocardial infarction, the time from telephone 911 emergency medical system (EMS) activation to treatment and its components were analyzed from eight separate ongoing trials. This included estimates of ambulance response time, prehospital evaluation and treatment time, and time from admission to the hospital to initiation of thrombolytic therapy. The average time from EMS activation to patient arrival at the hospital was prospectively determined to be 46.1 +/- 8.2 minutes in 3715 patients from eight centers. The time from admission to the hospital to initiation of thrombolytic therapy was retrospectively determined to be 83.8 +/- 55.0 minutes in a separate group of 730 patients from six centers. Both the prehospital and hospital time delays were much longer than those perceived by paramedics and emergency department directors. Shorter hospital time delays were observed in patients in whom a prehospital ECG was obtained as part of a protocol-driven prehospital diagnostic strategy and a diagnosis of acute infarction made before arrival at the hospital (36.3 +/- 11.3 minutes in 13 patients). These results show that the magnitude of time required to evaluate, transport, and initiate thrombolytic therapy will preclude initiation of treatment to most patients within the first hour of symptoms. Implementation of a protocol-driven prehospital diagnostic strategy may be associated with a reduction in time to thrombolytic therapy.