Safety and Feasibility of Trans Radial Percutaneous Coronary Intervention Approach in Elderly Patients with Acute Coronary Syndrome

Coronary catheterization is usually performed using the transfemoral approach but trans-radial has been increasingly used as an alternative to transfemoral approach due to less vascular complications, earlier ambulation time and improved patient comfort. The aim of the study was to compare the safety and feasibility of trans-radial and transfemoral PCI in the elderly ACS patients. This prospective observational study was conducted in the NICVD, Dhaka from October 2017 to September 2018. Total 80 patients were categorized into two groups according to the approach of PCI. Group I consists 40 patients who underwent trans-radial PCI and Group II consists 40 patients who underwent transfemoral PCI. Patients with abnormal Allen's test, history of CABG, CKD were excluded. Patient's demographics were same in both groups. The mean procedural time in min (37.44±5.13 vs. 34.42±4.42, p=0.004) and fluoroscopy time in min (21.6±4.11 vs. 17.55±2.78, p=0.02) were more in Group I but the mean hemostasis time in min (7.58±1.11 vs. 15.59±3.33, p=0.005) and the ambulation time in hour (0.00±0.00 vs. 15.59±3.33, p=0.001) were more in Group II. Significant arterial spasm following puncture (10.0% vs. 0.0%, p=0.01) were more in Group I. Post procedural major bleeding (0.0% vs. 10.0%, p=0.004), minor bleeding (10.0% vs. 20.0%, p=0.004) were significant in Group II but vessel occlusion (5.0% vs. 0.0%, p=0.02) were significant in Group I. Transradial PCI is safe in respect of procedural and post procedural vascular complications. Transradial procedure leads to improved quality of life after the procedure and thus gives much comfort to the patient. It also shortened mean duration of hospital stay. So transradial approach is an attractive alternative to conventional transfemoral approach in the elderly.

Impact of Myocardial Blush Grade on In-Hospital Outcome after Primary Percutaneous Coronary Intervention

Primary percutaneous coronary intervention (PPCI) is the optimal reperfusion strategy in patients with ST elevation Myocardial Infarction (STEMI). However, despite achieving TIMI 3 flow after PPCI, some patients have less optimal perfusion at the myocardial tissue level, as assessed by Myocardial Blush Grade (MBG) and consequently show adverse outcome. This prospective observational study was performed in the National Institute of Cardiovascular Diseases (NICVD), Dhaka, Bangladesh from March 2016 to February 2017. Total 74 patients with STEMI who underwent primary PCI and achieved TIMI 3 flow were included among them 37 patients were taken with low MBG (grade 0 or 1) in Group I and other 37 patients with high MBG (grade II or III) were taken in Group II. Mean age of Group I and Group II were 53.70±9.17 and 51.49±9.41 years respectively (p=0.536). Male to female ratio was 5.7:1. Smoking (59.5% versus 35.1%, p=0.036) and diabetes mellitus (43.2% versus 18.9%, p=0.024) were significantly higher in low MBG group than high MBG group. Multi vessel involvement (24.3% versus 5.4%, p=0.022) and anterior MI (72.9% versus 51.4%, p=0.047) were significantly higher in low MBG group. LVEF was significantly lower in low MBG group than high MBG group (49.92?6.60% versus 58.84?4.55%, p=0.003). Among the complications acute heart failure was found significantly higher in low MBG group than high MBG group (8.1% versus 0.0%, p=0.048) along with total adverse in hospital outcome (24.3% versus 5.4%, p=0.041). In study population total mortality was 2.7% and all were in low MBG group (5.4%). Multivariate logistic regression analysis showed MBG was an independent predictor of adverse in hospital outcome after PPCI (OR 6.553, 95% CI 1.984-21.643, p=0.002). Low MBG is associated with more adverse in hospital outcome after PPCI. So, along with TIMI 3 flow following PPCI we have to assess MBG for evaluation of complete reperfusion and further outcome.

Serum Albumin Level and In-Hospital Outcome of Patients with First Attack Acute Myocardial Infarction

Acute myocardial infarction (AMI) patients constitute a large proportion of admissions in coronary care unit and their management and risk stratification is of immense importance. A decrease in serum albumin concentration might be associated with an increased risk in the incident of both cardiovascular diseases and worse hospital outcome. We assessed whether serum albumin levels at admission was associated with in-hospital adverse outcome in patients with first attack of acute myocardial infarction (AMI). The aim of the study was to evaluate association of serum albumin level with in-hospital outcome in patients with first attack of acute myocardial infarction. This cross-sectional analytical study was conducted in the department of cardiology in Mymensingh Medical College Hospital, Mymensingh, Bangladesh from March 2017 to February 2018. Total 374 patients of first attack of acute myocardial infarction included considering inclusion and exclusion criteria. The sample population was divided into two groups: Group I (Patients with acute myocardial infarction with serum albumin <3.5gm/dl) and. Group II (Patients with acute myocardial infarction with serum albumin ≥3.5gm/dl). Serum albumin level was measured within 24 hours of admission and the incidence of in-hospital major cardiac outcomes was observed. In this study mean±SD serum albumin level of Group I, Group II were 3.02±0.12gm/dl, 4.48±0.50gm/dl respectively. In Group I patient, 52(59.80%), 7(8.00%), 10(11.50%), developed heart failure, cardiogenic shock, arrhythmias respectively and 8(9.20%) died and in Group II patient 20(7.90%), 7(2.80%), 8(3.20%) developed heart failure, cardiogenic shock, arrhythmias respectively and 4(1.60%) died out of them and all of these outcome were statistically significant. Mean±SD duration of hospital stay of the study population according serum albumin level, in Group I, 5.76±1.83 days, in Group II, 4.40±1.22 days which was statistically significant (p<0.05). In conclusion, patient with first attack of acute myocardial infarction serum albumin level below 3.50gm/dl increased the risk of worse in-hospital outcome.

Combination of Sonodynamic and Photodynamic Therapy against Cancer Would Be Effective through Using a Regulated Size of Nanoparticles

Nanoparticles have been used for many functional materials in nano-sciences and photo-catalyzing surface chemistry. The titanium oxide nanoparticles will be useful for the treatment of tumor by laser and/or ultrasound as the sensitizers in nano-medicine. We have studied the combination therapy of photo- and sono-dynamic therapies in an animal tumor model. Oral-administration of two sensitizers titanium oxide, 0.2%-TiO2 nanoparticles for sono-dynamic and 1 mM 5-aminolevulinic acid for photodynamic therapies have resulted in the best combination therapeutic effects for the cancer treatment. Our light microscopic and Raman spectroscopic studies revealed that the titanium nanoparticles were distributed inside the blood vessel of the cancer tissue (1-3 μm sizes). Among these nanoparticles with a broad size distribution, only particular-sized particles could penetrate through the blood vessel of the cancer tissue, while other particles may only exhibit the side effects in the model mouse. Therefore, it may be necessary to separate the optimum size particles. For this purpose we have separated TiO2 nanoparticles by countercurrent chromatography with a flat coiled column (1.6 mm ID) immersed in an ultrasonic bath (42 KHz). Separation was performed with a two-phase solvent system composed of 1-butanol-acetic acid-water at a volume ratio of 4:1:5 at a flow rate of 0.1 ml/min. Countercurrent chromatographic separation yielded fractions containing particle aggregates at 31 and 4400 nm in diameter.

Relaxation dynamics of liposomes in an aqueous solution

The gel–liquid crystal phase transition has been studied by the temperature and frequency dependent dielectric relaxation behavior of liposomes in an aqueous solution (40 g L⁻¹ DPPC–water mixture).

Advanced rheological characterization of soft colloidal model systems

The complex flow behavior of polymer-based soft colloidal model systems was investigated using steady and oscillatory shear to prove new concepts for advanced rheological characterization. In the very dilute regime we investigated high molecular weight polybutadiene star polymers to quantify the internal relaxation time arising from the polymeric nature of these ultra-soft colloids. The observed shear-induced brush deformation is interpreted in terms of the internal Zimm time τ(z). The observed dependence of τ(z) on matrix viscosity can be explained by shrinkage of the star polymer due to an increasing incompatibility with increasing matrix molecular weight. The influence of the polymeric nature on the characteristic structural relaxation time in the concentrated regime was investigated using non-linear rheology following Wyss et al (SRFS) (2007 Phys. Rev. Lett. 98 238303). Here we used star-like block copolymer micelles to systematically tune the 'softness' of the colloids by variation of the block ratio. A master curve with proper scaling parameters could be generated independent of the degree of colloidal 'softness'. However, the obtained strain-rate independent structural relaxation time τ(0) was not observed in the linear regime. In addition, a high frequency discrepancy was clearly found in all our experimental data. Both reflect the shortcomings of the SRFS approach.

Dielectric relaxation behavior of a liquid crystal showing an unusual type of antiferroelectric-ferroelectric-antiferroelectric phase sequence

The temperature and frequency dependent dielectric relaxation behavior of a liquid crystalline (S)-(+)-1-methylheptyl 4-[2-(4-alkoxyphenyl) thiophene-5-carbonylthiooxy] benzoate system is reported. Interesting successive antiferroelectric-ferroelectric-antiferroelectric (AF-FE-AF) phase transitions are observed in this system resembling the successive phase transitions observed in crystalline Rochelle salt. The smectic-C* (SmC*) to AF1 phase transition (around 103.0 degrees C) is first order in nature, predicted from the use of Orihara and Ishibashi theory. It is also found that a contribution of the ferroelectric SmC* phase ordering penetrates even in the antiferroelectric AF1 (SmC(*)(A)) and AF2 (SmC(*)(A)) phases very close to the SmC*-AF1 and SmC*-AF2 phase boundaries (critical regions). It is suggested that this type of mixing of AF and FE phases might cause surface induced ferroelectric- or ferroelectric-type ordering near the AF-FE phase transitions. A soft mode with Debye-type dispersion was observed in the SmA phase. The thermal behaviors of dielectric dispersion, absorption, and dielectric strength in different phases are also reported and discussed.

Dielectric investigation of electrically oriented ferroelectric smectic mixture CS-1013

From dielectric spectroscopic study, a first-order ferroelectric phase transition has been observed in ferroelectric smectic mixture CS-1013 having the phase sequence Cr-SmC*-SmA-N*-Iso. Frequency (100 Hz-10 MHz) and temperature-dependent dielectric measurements have been performed on an electrically aligned sample (thickness 15+/-1 microm) gold coated on glass plates. In the unidirectionally aligned sample, two dielectric relaxation modes (Goldstone mode and soft mode) have been clearly observed in the ferroelectric SmC* phase while only one relaxation mode (soft mode) is visualized in the paraelectric SmA phase. Low-frequency molecular relaxation was also observed in the smectic phases. The experimental results have also been analyzed at different temperatures and biasing voltages for an understanding of the dynamics of dielectric processes in the ferroelectric phase. Finally, we proposed the "pseudospin" model for understanding the ferroelectric-antiferroelectric transition in liquid crystals. We associate the tilt angle straight theta and the pitch of the helix, respectively, with biaxial (b) and uniaxial (u) anisotropy parameters as fluctuating parameters around their stability limit (corresponding to the crystalline values). Here, the director acts as the pseudospin variable. This gives rise to a transverse Ising type (or anisotropic Heisenberg model under the mean-field approximation). It is then shown that such a model with fluctuations of (b) and (u) would explain the ferroelectric and antiferroelectric phase transitions in such liquid crystals. Using Landau theory and the stability conditions, we have also shown, in brief, the feasibility of different types of phase transitions in the ferroelectric liquid crystal system.

In vivo persistence of donor cells following adoptive transfer of allogeneic dendritic cells in HIV-infected patients

Peripheral blood samples from HIV-seropositive individuals enrolled in a pilot clinical trial investigating the use of allogeneic dendritic cell therapy were evaluated for mixed chimerism. In this study, dendritic cells from HLA-identical, HIV-seronegative siblings were used. Patients received an infusion of dendritic cells pulsed with HIV MN gp160 protein or with peptides from HLA-A2 restricted epitopes of env, gag, and pol proteins every month for 6-9 months. Of the five allogeneic dendritic cell recipients, two showed increases in HIV antigen-specific immune responses. Allele-specific polymorphisms were identified in three sib-pairs that allowed infused donor cells to be detected using sensitive PCR-based molecular methods. Analysis of blood samples from patients showed similar patterns of donor cell persistence after the first infusion, in that cells were detectable for at least 1 week. Also, differences were observed in the kinetics of cell survival between the first and subsequent infusion cycles in all three patients. This suggests variation in HIV-specific immune responses detected among these three patients was not due to differences in persistence of infused donor cells.

Frequency of class I HLA-restricted anti-HIV CD8+ T cells in individuals receiving highly active antiretroviral therapy (HAART)

Peptide/MHC tetrameric complexes were used to enumerate the frequency of HLA class I-restricted epitope-specific CD8+ T cells in 18 HLA-A*0201 HIV type 1-infected asymptomatic patients. HLA-A*0201 molecules were complexed to HIV Gag p17 (amino acids 77-85) and reverse transcriptase (amino acids 464-472) peptides, biotinylated, and bound to streptavidin-phycoerythrin to form tetramers. We show in this study that 17 of 18 HIV-1-infected asymptomatic patients have circulating frequencies of 1/50-1/1000 CD8+ T cells that recognize both Gag and Pol CTL epitopes or either epitope alone. The functional nature of these cells is open to interpretation, as we show that despite relatively high frequencies of fresh epitope-specific CD8+ T cells, variant epitope sequences in viral plasma progeny were rare. In addition, the majority of tetramer-positive cells did not display discernible fresh CTL activity; only after restimulation with specific peptide in culture was there an expansion of epitope-specific CD8+ cells, correlating with high CTL activity. These data suggest that fresh tetramer-stained cells probably represent memory precursors; we demonstrate, with the application of highly active antiretroviral therapy, that the interruption of chronic antigenic stimulation causes significant reductions in the frequency of these cells in five of six patients. In conclusion, this study provides evidence that persistently replicating viral populations are probably required to maintain high frequencies of HIV-1 epitope-specific CD8+ T cells in asymptomatic chronically infected individuals

Variation in net photosynthesis, stomatal characteristics, leaf area and whole-plant phytomass production among ten provenances of neem (Azadirachta indica)

Variation in net photosynthesis, CO(2) exchange parameters, stomatal characteristics, leaf area and seedling dry weight were investigated among 10 provenances of neem (Azadirachta indica A. Juss.). Significant provenance variation was established for net photosynthesis (8.14 to 15.13 &mgr;mol m(-2) s(-1)), stomatal conductance (0.37 to 0.59 mol m(-2) s(-1)), stomatal density (145 to 204 mm(-2)), and total guard cell length (2681 to 3873 &mgr;m). Net photosynthesis was positively correlated with whole-plant dry weight and leaf area. Stomatal density was positively correlated with net photosynthesis, whole-plant dry weight, and leaf area. Total guard cell length was positively correlated with all of these traits. Information on six traits was used in a cluster analysis to construct a dendrogram to assess phenetic relationships among the provenances. With a few exceptions, the dendrogram revealed three major clusters grouped according to rainfall distribution. The study indicated that whole-plant phytomass production of neem seedlings was associated with photosynthesis and stomatal characteristics during the early stages of growth.

Role of preimmunization virus sequences in cellular immunity in HIV-infected patients during HIV type 1 MN recombinant gp160 immunization

The effect of patient preimmunization virus sequences on CTL responses during gp160 immunization were studied. Ten HLA-A2+, HIV+ asymptomatic patients with CD4+ T cells >500/mm3 were given two courses of HIV-1 MN rgp160 vaccine over a 2-year period. Envelope epitope-specific CTL responses, using PBMCs, were measured against peptide-coated autologous B lymphoblastoid cell lines. Optimum CTL epitopes were determined by HLA-A2-binding affinity of 9- to 10-mer peptides containing the HLA-A2.1-binding motif. Ten of the high- or intermediate-binding peptides were conserved among >50% of reported clade B HIV strains. These peptide-specific CTL activities and the patient virus sequences in peptide-coding regions were monitored. Six patients showed envelope peptide-specific CTL responses, which correlated with the presence of whole envelope antigen-specific CTL responses. Five of these patients, who showed responses to epitopes in the gp41 region (aa 814-824), had preimmunization virus similar to the vaccine sequence in this region. Three patients who did not show these epitope-specific responses had initially different sequences in the HIV gene encoding that region. The epitope-specific CTL responses appear to reflect recall responses, as only patients infected with virus containing the vaccine sequence developed them and they could be recalled with a second set of vaccine injections. This appears to be reminiscent of the concept of T cell "original antigenic sin." This vaccine was also immunogenic as measured by gp160-specific lymphocyte-proliferative responses. However, increased immune responses did not impact the HIV load or CTL epitope sequences during therapy.

A pilot clinical trial of HIV antigen-pulsed allogeneic and autologous dendritic cell therapy in HIV-infected patients

A pilot study was carried out to assess the safety and antigen-presenting properties of allogeneic or autologous dendritic cells (DCs) in six HLA-A2+, HIV-infected patients. Allogeneic DCs obtained from the peripheral blood of HLA-identical, HIV-seronegative siblings were pulsed with recombinant HIV-1 MN gp160 or synthetic peptides corresponding to HLA-A2-restricted cytotoxic epitopes of envelope, Gag, and Pol proteins. The antigen-pulsed cells were infused intravenously six to nine times at monthly intervals and HIV-specific immune responses were monitored. One allogeneic DC recipient with a CD4+ T cell count of 460/mm3 showed increases in envelope-specific CTL- and lymphocyte-proliferative responses, as well as in IFN-gamma and IL-2 production. Another allogeneic DC recipient with a CD4+ T cell count of 434/mm3 also showed an increase in HIV envelope-specific lymphocyte-proliferative responses. A recipient of autologous DCs with a CD4+ T cell count of 730/mm3 showed an increase in peptide-specific lymphocyte-proliferative responses after three infusions. Three other allogeneic DC recipients with CD4+ T cell counts <410/mm3 did not show increases in their HIV-specific immune responses. No clinically significant adverse effects were noted in this study and CD4+ T cell numbers and plasma HIV-1 RNA detected by RT-PCR of all six patients were stable during the study period. Thus, both allogeneic and autologous DC infusions were well tolerated and in patients with normal or near normal CD4+ T cell counts administration of these antigen-pulsed cells enhanced the immune response to HIV. However, since no effect on viral load was observed there was no evidence that this approach provided clinical benefit.

Generation of Primary Peptide-Specific Cd8+ Cytotoxic T-lymphocytes in Vitro using allogeneic dendritic cells

Dendritic ceils (DC) are potent antigen-presenting cells (APC) capable of inducing strong T-cell–mediated immunity. Infusion of lymphoma-specific antigen-loaded autologous DC has been demonstrated to result in the generation of antigen-specific immunity and reduction in tumor burden in B-cell lymphoma patients. Cellular immunotherapy employing antigen-loaded DC could have a potential therapeutic impact in tumors and viral infections, including HIV infection. However, DC in HIV-infected individuals and breast cancer patients are believed to be functionally defective. Therefore, the potential of using allogeneic DC offers significant implications for DC immunotherapy in AIDS and immunocompromised cancer patients. To explore the potential of allogeneic DC therapy in vivo, we tested the ability of allogeneic DC to generate primary peptide-specific CD8+ cytotoxic T-lymphocyte (CTL) responses in vitro. Our results indicate that DC from HLA class I-matched individuals elicit primary immune responses in vitro using viral peptides as naive antigens. A primary peptide-specific immune response could also be detected even when only one HLA allele (HLA-A*0201) was matched between the allogeneic DC and T-lymphocytes. The ability to generate primary peptide-specific responses in vitro is strongly indicative of the in vivo therapeutic potential of allogeneic DC.

Generation of primary peptide-specific CD8+ cytotoxic T-lymphocytes in vitro using allogeneic dendritic cells

Dendritic cells (DC) are potent antigen-presenting cells (APC) capable of inducing strong T-cell-mediated immunity. Infusion of lymphoma-specific antigen-loaded autologous DC has been demonstrated to result in the generation of antigen-specific immunity and reduction in tumor burden in B-cell lymphoma patients. Cellular immunotherapy employing antigen-loaded DC could have a potential therapeutic impact in tumors and viral infections, including HIV infection. However, DC in HIV-infected individuals and breast cancer patients are believed to be functionally defective. Therefore, the potential of using allogeneic DC offers significant implications for DC immunotherapy in AIDS and immunocompromised cancer patients. To explore the potential of allogeneic DC therapy in vivo, we tested the ability of allogeneic DC to generate primary peptide-specific CD8+ cytotoxic T-lymphocyte (CTL) responses in vitro. Our results indicate that DC from HLA class I-matched individuals elicit primary immune responses in vitro using viral peptides as naive antigens. A primary peptide-specific immune response could also be detected even when only one HLA allele (HLA-A*0201) was matched between the allogeneic DC and T-lymphocytes. The ability to generate primary peptide-specific responses in vitro is strongly indicative of the in vivo therapeutic potential of allogeneic DC.

Effect of therapeutic immunization with recombinant gp160 HIV-1 vaccine on HIV-1 proviral DNA and plasma RNA: relationship to cellular immune responses

Therapeutic vaccination has been proposed as a strategy to augment immune mechanisms to control viral replication and slow clinical progression of HIV infection to disease. Following recombinant gp160 (r-gp160) immunization in three clinical trials, plasma HIV-1 RNA and cellular proviral DNA were assessed by quantitative polymerase chain reaction (PCR) in 76 HIV-seropositive subjects with CD4+ T cell counts > or = 300/mm3. Immunization increased HIV-specific cellular immune responses (e.g., cytotoxic T lymphocyte [CTL] activities, lymphocyte proliferative responses); however, there were no significant effects of immunization or cellular immune responses on measures of plasma RNA or cellular DNA viral load.

Heterogeneity of cytokine functions in HIV infection

Immunological responses, especially cytokines, play important roles in determining the persistence of infectious agents in chronic diseases. Th1 responses enhance cellular immunity to control infection whereas Th2 immune responses down-regulate these effector immune responses. It has been suggested that the Th1 to Th2 switch is involved in human immunodeficiency virus (HIV) disease progression. We studied the regulatory role of interleukin-4 (IL-4; Th2 response) on interferon-gamma (IFN-gamma; Th1 response) in HIV infection and its role in the generation of HIV-specific cytotoxic T lymphocytes (CTL) in an in vitro system. Forty HIV-infected, asymptomatic individuals and 20 HIV-seronegative individuals were included in this study. Peripheral blood mononuclear cells were stimulated with phytohaemagglutinin and tetanus toxoid in the presence or absence of IL-4 to determine the effect of IL-4 on IFN-gamma production and HIV-Env-specific CTL activity. IL-4 showed a dual effect on IFN-gamma production in HIV patients. IL-4 down-regulated IFN-gamma production in HIV-seronegative individuals and in 55% of HIV patients whereas it stimulated IFN-gamma production in 45% of HIV patients. IL-4 increased HIV-Env-specific CTL activity in five of seven patients of the latter group. IL-4 has multiple biological activities, e.g. IL-4 inhibits IFN-gamma production as well as stimulates CTL generation which in turn produces IFN-gamma. Understanding the biological significance of these interactions is of importance for immunotherapeutic approaches against HIV infection.

Allogeneic dendritic cell induction of HIV-specific cytotoxic T lymphocyte responses from T cells of HIV type 1-infected and uninfected individuals

The potential benefit of T cell-based vaccination for HIV-1 infection remains to be determined. Cytotoxic T lymphocytes (CTLs) appear to clear substantial populations of HIV-1 virus in vivo, although CTL activity may contribute to the decline in CD4+ T cell count observed in the course of the disease. To investigate further the role of specific CTL responses in the control of HIV-1 replication, we raised primary CTL lines against a panel of conserved HIV-1 epitopes using blood-derived dendritic cells as antigen-presenting cells (APCs). Specific primary human CTL responses were induced against HLA-A*0201-restricted peptides with dendritic cells from HIV-1-seronegative donors. This method of immunization elicited cytotoxic activities capable of recognizing endogenously processed antigen. The CTL induction protocol was extended in order to explore the capacity of HLA-matched allogeneic dendritic cells to evoke novel CTL responses in T cells from an HIV-seropositive asymptomatic individual. Allogeneic peptide-pulsed dendritic cells from a healthy sibling were capable of eliciting a CTL response directed against an HIV epitope (env814: SLLNATDIAV) that was initially not detected in the CTL effector population of the HIV-1-infected patient. The possibility of manipulating CTL specificity directed against multiple conserved HIV-1 epitopes represents a significant step in the evaluation of T cell-based vaccination for treatment of disease.

Polyethylene glycol-modified interleukin-2 and thymosin alpha 1 in human immunodeficiency virus type 1 infection

The safety and antiviral effects of polyethylene glycolated interleukin-2 (PEG-IL-2) and thymosin alpha 1 in addition to zidovudine were studied in 12 human immunodeficiency virus (HIV)-infected subjects with 50-250 CD4 T cells/mm3. PEG-IL-2 was administered by intravenous infusions every 2 weeks at 10(6) IU/m2 for 20 weeks. Thymosin alpha 1 was administered subcutaneously at 400 microgram/m2 after four doses of PEG-IL-2, escalating to 1600 microgram/m2 weekly for an additional 2 months. Significant elevations of CD4 T cell numbers of 30%-40% were seen after PEG-IL-2 infusions, but no additional increase in CD4 cell count was observed with thymosin alpha 1. Virologic monitoring by polymerase chain reaction quantitation of proviral DNA and plasma RNA and p24 antigen assays showed no evidence of increased HIV activation during PEG-IL-2 or thymosin alpha 1 therapy. Patients tolerated both PEG-IL-2 and thymosin alpha 1 without significant toxicities.

Purification of commercial coomassie brilliant blue R-250 and characterization of the chromogenic fractions

Coomassie brilliant blue R-250 (CBB) is a popular and widely used dye for detection of proteins by gel electrophoresis. However, commercially available CBBs are complex mixtures of numerous chromogenic compounds that vary from lot to lot, thereby giving an undesirable level of variation in reproducibility, precision, and specificity in staining gels. We have developed a silica gel column chromatographic method for purification of commercial CBBs in high yield and have standardized each lot to perform equivalently in staining proteins as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and quantitative scanning densitometry. This is a major improvement in protein purity determinations by quantitative scanning densitometry. A thinlayer chromatographic method for quality control testing of the purified CBB lots was also developed. Plasma desorption mass spectrometry was used to identify components of silica gel column fractions. Scanning densitometry was the technology used to establish performance equivalency between different CBB preparations. The less polar chromogenic compounds are nonblue and/or fluorescent in color, contain mono- or unsulfonated structures, and lack significant protein binding capacity. The more polar chromogenic compounds are green and blue-green in color, contain tri- and tetrasulfonated moieties, compared to the disulfonated structure of CBB, and bind to protein at least 40 times more effectively than pure CBB. The concentrations of these highly polar chromogens differ from lot to lot and act as "inhibitors" in protein staining, thereby causing variability in protein staining.

Characterization of HLA-A 0201-restricted cytotoxic T cell epitopes in conserved regions of the HIV type 1 gp160 protein

CTL activity is a major component of the host immune response associated with control of HIV replication in the course of infection. Emerging populations of HIV overcome the protective effector mechanisms with variant sequences unrecognized by CTL. Therefore, a critical element for containment of virus spread might be the establishment of an immune response against highly conserved epitopes. In this study, we selected a panel of nonamer or decamer peptides, with demonstrated binding affinity for HLA-A 0201, to define novel highly conserved envelope-derived epitopes of HIV-1. CTL activities were characterized from PBMC of five HLA-A2+, HIV-1-infected individuals given recombinant gp160. CTL activity derived from patient PBMC stimulated in vitro with peptide was demonstrated against at least two novel minimal env-encoded conserved epitopes. One epitope, KLTPLCVTL (aa 120-128), is highly conserved among HIV-1 strains of the B subtype. Analysis of a CTL clone reactivity to a distinct epitope (aa 814-823) demonstrated fluctuations in the recognition of peptides corresponding to natural virus variants found in vivo.

Characterization of HLA-A 0201-restricted cytotoxic T cell epitopes in conserved regions of the HIV type 1 gp160 protein

CTL activity is a major component of the host immune response associated with control of HIV replication in the course of infection. Emerging populations of HIV overcome the protective effector mechanisms with variant sequences unrecognized by CTL. Therefore, a critical element for containment of virus spread might be the establishment of an immune response against highly conserved epitopes. In this study, we selected a panel of nonamer or decamer peptides, with demonstrated binding affinity for HLA-A 0201, to define novel highly conserved envelope-derived epitopes of HIV-1. CTL activities were characterized from PBMC of five HLA-A2+, HIV-1-infected individuals given recombinant gp160. CTL activity derived from patient PBMC stimulated in vitro with peptide was demonstrated against at least two novel minimal env-encoded conserved epitopes. One epitope, KLTPLCVTL (aa 120-128), is highly conserved among HIV-1 strains of the B subtype. Analysis of a CTL clone reactivity to a distinct epitope (aa 814-823) demonstrated fluctuations in the recognition of peptides corresponding to natural virus variants found in vivo.

Description of an in vitro platelet function analyzer--PFA-100

A new in vitro system for the detection of platelet dysfunction, PFA-100, has been developed. It provides a quantitative measure of platelet function in anticoagulated whole blood. The system comprises a microprocessor-controlled instrument and a disposable test cartridge containing a biologically active membrane. The instrument aspirates a blood sample under constant vacuum from the sample reservoir through a capillary and a microscopic aperture cut into the membrane. The membrane is coated with collagen and epinephrine or adenosine 5'-diphosphate. The presence of these biochemical stimuli, and the high shear rates generated under the standardized flow conditions, result in platelet attachment, activation, and aggregation, slowly building a stable platelet plug at the aperture. The time required to obtain full occlusion of the aperture is reported as the "closure time." We have found that impairment of von Willebrand factor, or inhibition of platelet receptors glycoprotein Ib or IIb/IIIa with monoclonal antibodies or peptides, resulted in abnormal closure times. An antifibrinogen antibody, in contrast, failed to show any effect. The test appears to be sensitive to platelet adherence and aggregation abnormalities. The PFA-100 system has potential applications in routine evaluation of platelet function in the clinical setting because of its accuracy, ease of operation, and rapid turnaround of results.

Relationship of HIV-1 provirus load, CD8+ CD11+ T cells and HIV-1 envelope-specific cytotoxic T lymphocytes in HIV-infected asymptomatic offients

The course of human immunodeficiency virus (HIV) infection progresses from an acute infection, through a prolonged asymptomatic phase, to an immunocompromised state. Some of the possible mechanisms underlying immune dysfunction include decreased HIV-specific cytotoxic T lymphocyte (CTL) activity, increased suppressor T cells, and/or increased HIV load. However, no study has been carried out to correlate all these factors. In this study, 26 patients showed > 3 log DNA copy number/10(6) CD4+ T cells, and seven patients had < 3 log DNA copy/10(6) CD4+ T cells. Patients with higher virus load had greater than 15% (19-45%) CD8+ CD11+ T cells. HIV-1 envelope-specific, HLA-restricted CTL activity (> 10%) was observed in 11 of 25 asymptomatic patients, and the remaining 14 patients lacked CTL activity (< 10%) in bulk assay. Although CTL activity was undetectable in these individuals, there was no significant difference in the frequency of activated CTL and their precursors in limiting dilution analysis. The patients with undetectable CTL activity had a higher percentage of CD8+ CD11+ T cells and a higher HIV-1 DNA copy number/million CD4+ T cells. Each of these parameters were significantly correlated with CD4+ T-cell numbers. The inverse relationship of CD8+ CD11+ T cells and virus load with HIV-specific CTL activity observed in this study may be one of the underlying factors which determines the course of HIV infection.

Effects of thermal exposure on binding of heparin in vitro to the arterial wall and to clot and on the chronic angiographic luminal response to local application of a heparin film during angioplasty in an in vivo rabbit model

Experimentally, heparin inhibits mechanisms that promote fibrosis, neointimal cellular proliferation, and thrombin bound to fibrin at the surface of intraluminal thrombus, but only in relatively high concentrations. A preliminary hypothesis was tested and confirmed in vitro that initial binding of 3H-heparin to mechanically injured porcine aorta is concentration-dependent over a 1,000-50,000 units/ml range (r = 0.9). The hypothesis was then tested in vitro that thermal exposure during contact of heparin to arterial tissue and to clot would enhance binding of the drug. 3H-heparin binding to clot, whole blood particulates, and washed erythrocytes was markedly enhanced by exposure to temperatures > 70 degrees C. Thermal exposure (80 degrees C x 40 s) also enhanced tissue persistence of the drug within porcine aorta subjected to a shear rate of 1,100(-1) in an annular Baumgartner chamber perfused with normal saline at 37 degrees C for 48 h. Heparin in vitro anticoagulant activity persisted after thermal exposure and binding to tissues. A new method was developed for local application of a heparin film that provides a maximum concentration with a tolerable systemic dose during an angioplasty procedure. In an in vivo rabbit model of mural fibrosis after iliac artery angioplasty, the 1-month mean angiographic luminal diameter loss (23% compared to the acute postangioplasty result by computer image analysis) in response to conventional balloon angioplasty (BA) and laser balloon angioplasty (LBA) was the same (P > 0.05). Local application of a heparin film (3,000 units at a concentration > 100,000 units/g), however, reduced the mean % loss in diameter 1 month after LBA (12%), but not after BA (29%), compared to arteries subjected to angioplasty without local heparin (P < .05). The results are consistent with the hypothesis that thermal energy enhances heparin binding to tissues and that local application of a heparin film favorably modulates arterial luminal responses to LBA, but not to BA, in this animal model.

Safety and efficacy of polyethylene glycol-modified interleukin-2 and zidovudine in human immunodeficiency virus type 1 infection: a phase I/II study

The safety and efficacy of combined therapy with polyethylene glycolated (PEG) interleukin (IL)-2 and zidovudine was assessed in 19 human immunodeficiency virus type 1 (HIV-1)-seropositive subjects in a phase I/II open-label dose-ranging study. During courses of three weekly infusions of PEG IL-2, dose-limiting side effects were seen at 5 x 10(6) IU/m2 and reversible encephalopathy in 1 subject at 3 x 10(6) IU/m2. Significant increases were seen in CD4 cell counts (P < .01), NK cell activity (P < .05), and HIV-specific cytotoxicity (P < .01). Virologic monitoring (quantitative DNA polymerase chain reaction and p24 antigen assay) showed no evidence of increased HIV activation. Patients with CD4 cells < 200/mm3 were entered into a chronic dosing phase. PEG IL-2 was given at 14-day intervals at doses of 10(6) IU/m2 for 8 weeks and 3 x 10(6) IU/m2 for up to 16 weeks, resulting in mean CD4 cell count elevations of 16% and 33%, respectively. PEG IL-2 appears to warrant further investigation, especially in subjects with CD4 cell counts < 200/mm3, to determine whether increased lymphocyte numbers will translate into improved clinical outcome.

Enhancement of human immunodeficiency virus (HIV)-specific CD4+ and CD8+ cytotoxic T-lymphocyte activities in HIV-infected asymptomatic patients given recombinant gp160 vaccine

Twenty-six human immunodeficiency virus (HIV)-infected asymptomatic patients with CD4+ lymphocytes > 400 per mm3 were randomly allocated to a range of doses of recombinant gp160 or a control (recombinant hepatitis B vaccine) on a double-blind basis. Each patient received an injection at 0, 4, 12, 24, 36, and 48 weeks. Treatment assignments were decoded when all patients reached 28 weeks of the study period. HIV-1-specific CD4+ and CD8+ cytotoxic T lymphocyte (CTL) activities were assessed in vitro before vaccination and 2 weeks after each injection. There were significant increases in major histocompatibility complex-restricted HIV-1 Env-specific CD4+ and CD8+ CTL activities in 18 of 21 gp160 vaccinees. No control-injected patients showed a significant change. Neither gp160 nor control recipients showed significant changes in HIV-1 Gag- and Pol-specific CTL activities. HIV-1 Env-specific CD4+ and CD8+ CTL precursor frequencies were also measured in three vaccinees before and at 24 weeks after vaccine was started. CTL precursor frequencies also increased in both CD4+ and CD8+ populations. This study shows that this gp160 vaccine is immunogenic in enhancing HIV-1 Env-specific cytotoxic T-cell-mediated immunity in HIV-seropositive individuals.

Breath acetone analyzer: diagnostic tool to monitor dietary fat loss

Acetone, a metabolite of fat catabolism, is produced in excessive amounts in subjects on restricted-calorie weight-loss programs. Breath acetone measurements are useful as a motivational tool during dieting and for monitoring the effectiveness of weight-loss programs. We have developed a simple, easy-to-read method that quantifies the amount of acetone in a defined volume of exhaled breath after trapping the sample in a gas-analyzer column. The concentration of acetone, as measured by the length of a blue color zone in the analyzer column, correlates with results obtained by gas chromatography. Using the breath acetone analyzer to quantify breath acetone concentrations of dieting subjects, we established a correlation between breath acetone concentration and rate of fat loss (slope 52.2 nmol/L per gram per day, intercept 15.3 nmol/L, n = 78, r = 0.81). We also discussed the possibility of using breath acetone in diabetes management.

Breath acetone analyzer: diagnostic tool to monitor dietary fat loss

Acetone, a metabolite of fat catabolism, is produced in excessive amounts in subjects on restricted-calorie weight-loss programs. Breath acetone measurements are useful as a motivational tool during dieting and for monitoring the effectiveness of weight-loss programs. We have developed a simple, easy-to-read method that quantifies the amount of acetone in a defined volume of exhaled breath after trapping the sample in a gas-analyzer column. The concentration of acetone, as measured by the length of a blue color zone in the analyzer column, correlates with results obtained by gas chromatography. Using the breath acetone analyzer to quantify breath acetone concentrations of dieting subjects, we established a correlation between breath acetone concentration and rate of fat loss (slope 52.2 nmol/L per gram per day, intercept 15.3 nmol/L, n = 78, r = 0.81). We also discussed the possibility of using breath acetone in diabetes management.

An in vitro evaluation of the effect of laser irradiation on the thrombogenicity of thrombus

The effect of laser irradiation on the thrombogenicity of thrombus was evaluated by treating thrombi, formed in-vitro from canine blood, with two different doses of cw Nd:YAG laser energy at 1064 nm. The thrombi were then incubated with whole blood, and the plasma levels of fibrinogen and thrombin-antithrombin III-complexes were measured. A statistically significant decrease (p < 0.05) in the thrombogenicity was indicated by a reduction in both fibrinogen consumption and levels of thrombin-antithrombin III-complexes in the high dose group (600 joules, 100 degrees C peak temperature) in comparison to the low dose group (300 joules, 70 degrees C peak temperature) and the untreated thrombi. These findings suggest that laser irradiation of thrombus at an appropriate dose may substantially reduce its thrombogenicity and ability to modulate hemostasis.

Equivalent recognition of HIV proteins, Env, Gag and Pol, by CD4+ and CD8+ cytotoxic T-lymphocytes

OBJECTIVES

Cytotoxic T-lymphocytes (CTL) appear to be an important defense mechanism against HIV infection. This study proposes to examine the major histocompatibility complex (MHC)-restricted HIV-1 Env-, Gag- and Pol-specific CTL activities in HIV-infected asymptomatic patients.

DESIGN

CD4+ and CD8+ CTL were examined to establish whether the same HIV-1 protein (Env, Gag or Pol) was recognized by both CD4+ and CD8+ CTL with MHC antigen restriction.

METHODS

Peripheral blood mononuclear cells, CD4+ and CD8+ T-cells from 17 HIV-infected asymptomatic patients and 10 HIV-seronegative individuals were examined for HIV-1 Env-, Gag- and Pol-specific MHC-restricted cytotoxicity using autologous and heterologous B-lymphoblastoid cell lines infected with vaccinia recombinant expressing HIV-1 Env, Gag and Pol proteins as targets.

RESULTS

CD4+ and CD8+ CTL specific for the HIV-1 Env, Gag and Pol were demonstrated in the peripheral blood. DR4 and DQw2 were possible sites of MHC class II restriction of CD4+ CTL. Possible MHC class I restriction sites of CD8+ CTL included A2 and B8 for Env, A1 and A2 for Gag, and A2 and B8 for Pol antigen.

CONCLUSIONS

These observations should help to define more precisely the nature and elements of protective immunity and to evaluate AIDS vaccine strategies.

CD8+CD11+Suppressor Cells in HIV-Infected Asymptomatic Patients: Effect on HIV-Specific Cytotoxicity

CD3+CD8+CD11+ cells were present in the peripheral blood of patients infected with asymptomatic human immunodeficiency virus (HIV) in higher percentage (10-20%) than in normal individuals (3-5%) in this study. These cells, through the release of soluble factors, significantly suppressed the effector phase of anti-HIV cytotoxic activities, both human leukocyte antigen (HLA)-class I or class II restricted, and nonrestricted. The effectors were CD8+CD11-, CD4+ T cells, and CD16+ cells for HLA-class I, class II restricted, and nonrestricted cytotoxicities, respectively. The soluble factors also inhibited natural killer cell activity. Thus, this effect was neither HLA-restricted nor antigen-specific. These CD3+CD8+CD11+ cells may be an important immunopathogenic factor in HIV disease.

Inverse relationship of CD8+CD11+ suppressor T cells with human immunodeficiency virus (HIV)-specific cellular cytotoxicity and natural killer cell activity in HIV infection

Profiles of CD8+CD11+ T suppressor cells, human immunodeficiency virus (HIV)-env-specific cytotoxic T-lymphocyte (CTL) activities, and natural killer (NK) cell activity were studied in 12 asymptomatic untreated HIV-infected patients. These patients were followed for 4-7 months. NK activity, HIV-env-specific CTL activities mediated by CD4+, CD8+ T cells and CD8+CD11+ T-suppressor cell number remained stable in seven patients during the study period. Alternatively, NK and HIV-specific CTL activities decreased and CD8+CD11+ cell number increased in five patients whose CD4+ T-cell number fell, and in four of these five patients serum p24 antigen level increased, and they developed minor clinical signs of disease progression during the study period. CD8+CD11+ cells are present in higher percentage (10-45% of peripheral blood mononuclear cells) in these HIV-infected patients as compared to those in normal individuals (3-5%). Our results suggest that CD8+CD11+ cells, NK, and HIV-specific cytotoxic activities may be helpful in monitoring prognosis of HIV infection. These observations also suggest that CD8+CD11+ cells may play an important role in the failure of host immune defences against HIV.

Novel solid-phase assay of ketone bodies in urine

This simple dip-and-read color-matching assay measures ketone bodies in urine. The result is matched with any of the seven colors provided in a color chart. The intensity and hue of the color formed depends on the concentration of acetoacetic acid and follows a gradation starting from light purple (0.2 mol/L acetoacetate) to dark purple and finally to dark violet (9 mol/L). The color developed is independent of pH in the range pH 4-9.5, and is stable for at least 1 h. 3-Hydroxybutyric acid produced no color at the concentrations tested (less than or equal to 100 mmol/L), and acetone was detectable only when greater than or equal to 15 mmol/L. The test was compared with the Ames Ketostix assay in subjects who were on restricted-calorie weight-loss programs. The two methods showed good agreement, except that 20% (21/103) of samples that were negative by Ketostix were read as positive by the new method, which may be more sensitive (detection limit = 0.2 mmol/L). Measurement of urine ketones was unreliable (in comparison with measurement of blood or breath acetone) for monitoring the rate of fat loss during a negative calorie balance.

Novel solid-phase assay of ketone bodies in urine

This simple dip-and-read color-matching assay measures ketone bodies in urine. The result is matched with any of the seven colors provided in a color chart. The intensity and hue of the color formed depends on the concentration of acetoacetic acid and follows a gradation starting from light purple (0.2 mol/L acetoacetate) to dark purple and finally to dark violet (9 mol/L). The color developed is independent of pH in the range pH 4-9.5, and is stable for at least 1 h. 3-Hydroxybutyric acid produced no color at the concentrations tested (less than or equal to 100 mmol/L), and acetone was detectable only when greater than or equal to 15 mmol/L. The test was compared with the Ames Ketostix assay in subjects who were on restricted-calorie weight-loss programs. The two methods showed good agreement, except that 20% (21/103) of samples that were negative by Ketostix were read as positive by the new method, which may be more sensitive (detection limit = 0.2 mmol/L). Measurement of urine ketones was unreliable (in comparison with measurement of blood or breath acetone) for monitoring the rate of fat loss during a negative calorie balance.

Laser balloon angioplasty: potential for reduction of the thrombogenicity of the injured arterial wall and for local application of bioprotective materials

Mitigation of adverse biologic reactivity after balloon angioplasty is necessary before the incidence of restenosis can be appreciably reduced. A brief review of experimental evidence supports the hypothesis that the thrombogenicity of the injured arterial wall can be reduced by a suitable level of thermal denaturation or cross-linking of thrombogenic proteins. In addition, the concept of local pharmacologic therapy, which can be provided with laser balloon angioplasty at the site of arterial injury, is introduced. Preliminary in vitro and in vivo data suggest that guide catheter-injected albumin-heparin conjugates fabricated as water-insoluble microspheres remain adherent to the injured luminal surface and deeper arterial layers after physical trapping by the inflated balloon and subsequent laser/thermal exposure. The combination of initially adequate luminal morphology, reduction of the thrombogenicity of the injured arterial wall and application of local pharmacologic therapy with laser balloon angioplasty may eventually prove helpful in reducing the incidence of restenosis.

ECMO without heparin: laboratory and clinical experience

To evaluate the feasibility of long-term extracorporeal membrane oxygenation (ECMO) without heparin, we placed six lambs on standard venoarterial ECMO for 71 to 96 hours. Group 1 (3 animals) was given doses of heparin to maintain activated clotting times (ACT) greater than 400 seconds. No form of anticoagulant was used for the three animals in group 2. Blood flow was maintained at 60 mL/kg/min. No histological evidence of thrombosis was noted at necropsy. ACT, prothrombin time, and partial thromboplastin time were higher in group 1, and much lower, although still above normal in group 2. Fibrinogen was significantly lower in group 2 (75 +/- 35 v 219 +/- 64 mg/dL group 1), and, although the platelet count was lower in group 2 (142 +/- 76 x 10(3)/mm3 v 225 +/- 167 x 10(3)/mm3), it was clinically acceptable. These results encouraged us to discontinue heparin when faced with severe hemorrhage in four patients on ECMO, rather than withdraw support at a time when there was little chance of survival. Heparin was discontinued for 10.5 +/- 6 hours. The mean ACT was reduced from 220 +/- 23 seconds to 144 +/- 22 seconds. One patient, who required repair of gastric necrosis while on ECMO following repair of a congenital diaphragmatic hernia, survived and had a decrease in blood loss from 2 to 0 mL/kg/h after the heparin was discontinued. One of the three patients who died had an autopsy with no evidence of thrombosis. We conclude that it may be reasonable to discontinue heparin in the face of life-threatening hemorrhage while on ECMO.

Role of Vicia villosa-adherent CD8+ T cells in the immune response to Epstein-Barr virus

Epstein-Barr virus (EBV) is a lymphotropic human herpesvirus which is also a polyclonal B-cell activator. We show here that Vicia villosa-adherent CD8+ T (VV-T) cells, which have a contrasuppressive activity, play an important role in the B-cell response to EBV and that T-helper cells are not required for antibody production against EBV particles. We have examined this activity by measuring anti-EBV IgM antibody production by B cells in vitro in the presence and the absence of both T-helper and VV-T cells. The presence or absence of T-helper cells did not affect antibody production. Our results suggest that the antigen-presenting activity of VV-T cells was virus specific, while the contrasuppressive activity was not. Control experiments carried out in parallel using human cytomegalovirus (CMV) produced similar results also for CMV-specific IgM production. Taken together, our data lead us to hypothesize that VV-T cells might also play other roles in EBV infections: on the one hand, by presenting EBV to B cells, VV-T cells could contribute to the spread of viral infection of B lymphocytes, as the latter are the exclusive targets for EBV immortalization within the immune system; on the other hand, by inhibiting the effect of T-suppressor cells on T-helper cells, VV-T cells could indirectly help the latter maintain their lymphokine producing activity, especially interleukin-2 and interferon-gamma production, which in turn could directly or indirectly (i.e., by stimulating natural killer and T cells) contribute to control of the EBV infection.

Regional blood flow distribution during extracorporeal membrane oxygenation in rabbits

To study regional blood distribution during extracorporeal membrane oxygenation, we stabilized three groups of five rabbits each (3 to 5 kg) on venoarterial bypass at a flow rate of 30 ml/kg/min. Albumin aggregates (15 to 30 microns) labeled with technetium 99m were injected into the left ventricle during bypass (ventricle), the perfusion cannula during bypass (cannula), and the left ventricle with no bypass (control). Animals were put to death, organs were removed, and the percent distribution was determined with a gamma camera. The Student Newman-Keuls test was used for statistical comparisons. Distribution to both the heart and brain in the cannula group were decreased from control by 55% and 35%, respectively. Distribution to the brain in the ventricle group was also decreased from control by 39%. Intestinal distribution was elevated above control in the ventricle group by 37%, whereas musculoskeletal distribution was elevated 33% above control in the cannula group. No significant changes were noted for the kidneys, stomach, or liver. These data suggest that overall perfusion of some vital organs may be significantly reduced during low-flow extracorporeal membrane oxygenation, specifically in the case of the heart and brain, which may be deprived of oxygenated blood.

Regional blood flow during extracorporeal membrane oxygenation in lambs

To determine changes in blood flow to different organs during extracorporeal membrane oxygenation (ECMO), the authors performed venoarterial ECMO in four young lambs for 71-96 hr (Group 1). Macroaggregated albumin microspheres labeled with technetium 99m were injected through the perfusion cannula before termination of ECMO to determine percent of blood flow by measuring radioactivity from the microspheres lodged in specific organs. The control group (Group 2) consisted of three animals not on bypass; injections were made through a catheter placed in the left ventricle. Relative coronary blood flow from the perfusion cannula was significantly less than relative coronary blood flow in the control group, possibly because of cannula location. Renal flow from the perfusion cannula also was decreased. Contrary to observations in rabbits, cerebral perfusion did not decrease in the bypass group despite ligation of the carotid artery and the external jugular vein. There were no statistically significant differences between the two groups in the relative blood flow to other organs. The authors conclude that ECMO may significantly alter myocardial and renal perfusion, with minimal effects to other organs.

Extracorporeal membrane oxygenation without anticoagulation: a study using quantitative scanning electron microscopy

In current clinical applications of extracorporeal circulation (ECC) of blood, heparin is administered to prevent thrombosis in the circuit and to eliminate thromboembolism in the patient. Systemic heparinization, however, causes impairment of normal coagulation properties and significantly increases the risks of major bleeding complications. It has been observed in the past that ECC may be performed in the absence of any systemic anticoagulants or material surface treatments. In this study, short-term extracorporeal membrane oxygenation (ECMO) was performed on rabbits in three groups. The animals in the first group received standard clinical dosages of heparin. No form of anticoagulation was used in the second group. The ECMO circuits in the third group were treated with an albumin-heparin complex surface-coating. Thrombosis in the extracorporeal circuit was evaluated by using quantitative scanning electron microscopy. The results indicated very few statistically significant differences between the three experimental systems in the amounts of blood components adhering to the surface. Considerably more platelet activation and attachment was noted in the systemic heparin group. These experiments failed to demonstrate any benefit of systemic heparinization in short-term ECMO. The findings from these experiments suggest that the current levels of systemic heparinization may be unwarranted, and they indicate that more controlled studies must be performed to determine optimal levels of anticoagulation for different applications of ECC.

Interleukin-2 induced killer cell activity against Epstein-Barr virus-immortalized human B cells

Interleukin-2 (IL-2) activated killer (LAK) cells, generated in vitro by treating peripheral blood lymphocytes (PBL) with human IL-2, are able to lyse a wide variety of target cells without restriction by major histocompatibility complex (MHC) molecules. Earlier observations from this and other laboratories indicated that patients with Epstein-Barr virus (EBV) induced infectious mononucleosis, a self-limiting viral disease, have high EBV-non-specific natural killer (NK) cell activity. Since the effect of LAK cells on EBV-immortalized B lymphocytes has not yet been studied, we decided to investigate LAK cell activity against autologous and heterologous B lymphocytes immortalized in vitro by EBV and other EBV genome-positive and -negative targets of malignant origin. LAK activity was determined by 51Chromium release assay. The results obtained show that LAK activity was not specific for EBV and was not MHC-restricted. Results of experiments using NK cell reactive monoclonal antibodies suggest that the cytotoxicity is due predominantly to activated NK cells. Our observations suggest that LAK cells may be very effective for immunotherapy in patients with chronic or progressive EBV infections and EBV-induced lymphoproliferative diseases.