Evaluation of electropolymerized molecularly imprinted polymers (E-MIPs) on disposable electrodes for detection of SARS-CoV-2 in saliva.

We investigate electropolymerized molecularly imprinted polymers (E-MIPs) for the selective recognition of SARS-CoV-2 whole virus. E-MIPs imprinted with SARS-CoV-2 pseudoparticles (pps) were electrochemically deposited onto screen printed electrodes by reductive electropolymerization, using the water-soluble N-hydroxmethylacrylamide (NHMA) as functional monomer and crosslinked with N,N'-methylenebisacrylamide (MBAm). E-MIPs for SARS-CoV-2 showed selectivity for template SARS-CoV-2 pps, with an imprinting factor of 3:1, and specificity (significance = 0.06) when cross-reacted with other respiratory viruses. E-MIPs detected the presence of SARS-CoV-2 pps in <10 min with a limit of detection of 4.9 log10 pfu/mL, suggesting their suitability for detection of SARS-CoV-2 with minimal sample preparation. Using electrochemical impedance spectroscopy (EIS) and principal component analysis (PCA), the capture of SARS-CoV-2 from real patient saliva samples was also evaluated. Fifteen confirmed COVID-19 positive and nine COVID-19 negative saliva samples were compared against the established loop-mediated isothermal nucleic acid amplification (LAMP) technique used by the UK National Health Service. EIS data demonstrated a PCA discrimination between positive and negative LAMP samples. A threshold real impedance signal (ZRe) ≫ 4000 Ω and a corresponding charge transfer resistance (RCT) ≫ 6000 Ω was indicative of absence of virus (COVID-19 negative) in agreement with values obtained for our control non-imprinted polymer control. A ZRe at or below a threshold value of 600 Ω with a corresponding RCT of <1200 Ω was indicative of a COVID-19 positive sample. The presence of virus was confirmed by treatment of E-MIPs with a SARS-CoV-2 specific monoclonal antibody.

The major histocompatibility complex homozygous inbred Babraham pig as a resource for veterinary and translational medicine.

The Babraham pig is a highly inbred breed first developed in the United Kingdom approximately 50 years ago. Previous reports indicate a very high degree of homozygosity across the genome, including the major histocompatibility complex (MHC) region, but confirmation of homozygosity at the specific MHC loci was lacking. Using both direct sequencing and PCR-based sequence-specific typing, we confirm that Babraham pigs are essentially homozygous at their MHC loci and formalise their MHC haplotype as Hp-55.6. This enhances the utility of the Babraham pig as a useful biomedical model for studies in which controlling for genetic variation is important.

Pathology and Virus Distribution in the Lung and Lymphoid Tissues of Pigs Experimentally Inoculated with Three Distinct Type 1 PRRS Virus Isolates of Varying Pathogenicity.

Porcine reproductive and respiratory syndrome (PRRS) continues to be the most economically important disease of swine worldwide. The appearance of highly pathogenic PRRS virus (PRRSV) strains in Europe and Asia has raised concerns about this disease and initiated increased efforts to understand the pathogenesis. In this study, we have compared the pathology and the virus distribution in tissues of pigs experimentally inoculated with three different genotype 1 PRRSV isolates. Sixty 5-week-old pigs were inoculated intranasally with a) the Lelystad virus (LV), b) a field strain from the UK causing respiratory clinical signs (UK) or c) a highly pathogenic strain from Belarus (BE). Sixteen animals were mock-infected and used as controls. The animals were euthanized at 3, 7 and 35 days post-infection (dpi), and lung and lymphoid tissues collected for histopathological examination and PRRSV detection by immunohistochemistry (IHC). Histopathological lesions consisted of interstitial pneumonia with mononuclear cell infiltrates in the lungs, lymphoid depletion, apoptosis and follicular hyperplasia in the spleen, lymph nodes and tonsil and lymphoid depletion in the thymus. Porcine reproductive and respiratory syndrome virus was detected mainly in monocytes-macrophages. BE-infected animals showed the highest pathological scores and the highest presence of virus at 3 and 7 dpi, followed by the UK field strain and then LV. Moderate lesions were observed at 35 dpi with lesser detection of PRRSV by IHC in each infected group. The highly pathogenic BE strain induced more severe pathology in both lungs and lymphoid organs of pigs compared with the classic field isolate and the prototype LV. The increased severity of pathology was in correlation with the presence of a higher number of PRRSV-infected cells in the tissues.

Increased pathogenicity of European porcine reproductive and respiratory syndrome virus is associated with enhanced adaptive responses and viral clearance.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically important diseases of swine worldwide. Since its first emergence in 1987 the PRRS virus (PRRSV) has become particularly divergent with highly pathogenic strains appearing in both Europe and Asia. However, the underlying mechanisms of PRRSV pathogenesis are still unclear. This study sets out to determine the differences in pathogenesis between subtype 1 and 3 strains of European PRRSV (PRRSV-I), and compare the immune responses mounted against these strains. Piglets were infected with 3 strains of PRRSV-I: Lelystad virus, 215-06 a British field strain and SU1-bel from Belarus. Post-mortem examinations were performed at 3 and 7 days post-infection (dpi), and half of the remaining animals in each group were inoculated with an Aujeszky's disease (ADV) vaccine to investigate possible immune suppression resulting from PRRSV infection. The subtype 3 SU1-bel strain displayed greater clinical signs and lung gross pathology scores compared with the subtype 1 strains. This difference did not appear to be caused by higher virus replication, as viraemia and viral load in broncho-alveolar lavage fluid (BALF) were lower in the SU1-bel group. Infection with SU1-bel induced an enhanced adaptive immune response with greater interferon (IFN)-γ responses and an earlier PRRSV-specific antibody response. Infection with PRRSV did not affect the response to vaccination against ADV. Our results indicate that the increased clinical and pathological effect of the SU1-bel strain is more likely to be caused by an enhanced inflammatory immune response rather than higher levels of virus replication.

Characterisation of experimental infections of domestic pigs with genotype 2.1 and 3.3 isolates of classical swine fever virus.

The early identification of classical swine fever epizootics is hampered by difficulties in recognising early signs of infection, due to a lack of specific clinical signs. In addition many textbook descriptions of CSF are based on observations of disease caused by historic, mainly genotype 1, strains. Our objective was to improve our knowledge of the diverse range of signs that different CSFV strains can cause by characterising the experimental infection of domestic pigs with both a recent strain of CSFV and a divergent strain. Conventional pigs were inoculated with a genotype 2.1 isolate, that caused an outbreak in the UK in 2000, and a genotype 3.3 strain that is genetically divergent from European strains. This latter strain is also antigenically distinct as it is only poorly recognised by the CSFV-specific monoclonal antibody, WH303. Transmission was monitored by use of in-contact animals. Clinical, virological and haematological parameters were observed and an extended macro- and histopathological scoring system allowed detailed characterisation of pathological lesions. Infection with the genotype 2.1 isolate resulted in a similar outcome to other recent genotype 2 European strains, whereas the genotype 3.3 strain produced fewer and delayed clinical signs, notably with little fever. This strain would therefore be particularly difficult to detect in the early stages of infection and highlights the importance of encouraging early submission of samples for laboratory diagnosis. As representatives of recent and divergent CSFV isolates, these strains are good candidates to study the pathogenesis of current CSFV isolates and as challenge models for vaccine development.

Characterization of efferent lymph cells and their function following immunization of cattle with an allogenic Theileria annulata infected cell line.

Immunization of cattle with in vitro propagated bovine mononuclear cells infected with Theileria annulata induces a protective immune response. Activation and effector function of T cells exiting the lymph node draining the site of cell line immunization were investigated to understand the mechanisms involved in the generation of immunity. Immunized animals exhibited a biphasic immune response in efferent lymph as well as peripheral blood. The first phase corresponded to allogenic responses against MHC antigens of the immunizing cell line and the second was associated with parasite specific responses. An increase in the output of CD2(+) cells and MHC class II(+) cells in efferent lymph was observed after cell line immunization with a corresponding decrease in WC1(+) cells. Although the percentage of CD4(+) T cells did not change significantly over the course of the experiment, they became activated. Both CD25 and MHC class II expressing CD4(+) T cells were detected from day 7 onwards, peaking around day 13. Efferent lymph leukocytes (ELL) exhibited sustained responses to IL-2 in vitro following cell line immunization. Antigen specific proliferation was also detected first to the immunizing cell line and then to parasite antigens. The two peaks of CD2(+) cells were observed, which corresponded to similar peaks of CD8(+) cells. The increase in CD8(+) cells was more pronounced during the second parasite specific phase than the first allogenic phase. Activated CD8(+) T cells mainly expressed MHC class II and some expressed CD25. Significantly the peak of activated CD4(+) T cells preceded the peak of activated CD8(+) T cells, highlighting the role of T. annulata specific CD4(+) T cells in inducing parasite specific CD8(+) cytotoxic responses. A biphasic cytotoxic response also appeared in efferent lymph and peripheral blood, the first directed against MHC antigens of the immunizing cell line followed by MHC class I restricted parasite specific cytotoxicity. The cytotoxic responses in efferent lymph appeared earlier than peripheral blood, suggesting that activated CD8(+) cells exiting the draining lymph node following immunization with T. annulata infected schizonts play an important role in the development of protective immune responses.

To anticoagulate or not to anticoagulate patients with cardiomyopathy.

The current published literature does not indicate whether the long-term effect of anticoagulant or antiplatelet therapy contributes to mortality reduction in patients with LV dysfunction. Evaluating patients for personal risk for emboli or for ischemic coronary artery events may influence the choice of therapies. As more is learned about the mechanisms of drug effects in different populations, physicians may be better able to direct appropriate therapies. Until that time, one must weigh the risks and benefits of each drug alone and in combination. In NYHA class IV patients, the risk for thrombosis owing to spontaneous clotting increases as does the adverse potential of warfarin and the adverse effects of inhibiting prostaglandin mediated vasodilation by aspirin. In NYHA class I and II patients, the quality of life and convenience of multidrug therapy is weighed against the devastating effect of a major stroke. In less symptomatic patients, the long-term risk for acute coronary events may be higher than previously identified. This would suggest that all patients with depressed LV function should be on some type of antiplatelet or anticoagulant therapy. The current WATCH study will provide much needed information about the outcome differences between these agents. Conclusions based on available data include the following: Heart failure is increasing in incidence and prevalence. Atherosclerotic disease is an important causative factor for the development of heart failure or may be a comorbid condition in these patients. There is a measurable rate of stroke in patients with heart failure, although the cause of death in large studies is more often owing to sudden death or progressive heart failure. Sudden death may be from new ischemic events, asystole, or from ventricular tachyarrhythmias. In patients with heart failure, not all strokes are cardioembolic in origin. The benefits and risks of warfarin may be increased as the EF worsens or heart failure functional class declines. The interactions of aspirin and ACE inhibitors have been best evaluated for the hemodynamic effects. There may be additional factors hitherto not studied. The hemodynamic effect of ACE inhibitors may be more important in NYHA classes III and IV than in less symptomatic patients. Warfarin use has clear indications for patients in atrial fibrillation with mechanical prosthetic valves, in hypercoagulable states, and with a previous history of embolization. Aspirin is inexpensive and commonly available, but its use must be evaluated and articulated by the prescribing physician. The current multicenter prospective trials will provide much needed guidance on this subject. The ongoing trials do not have a placebo arm, however, indicating a consensus among clinicians that patients with cardiomyopathy should be on an antiplatelet or anticoagulant drug until further data emerge.

Down-regulated lymphoproliferation coincides with parasite maturation and with the collapse of both gamma interferon and interleukin-4 responses in a bovine model of onchocerciasis.

Onchocerciasis is a debilitating parasitic infection caused by the filarial nematode Onchocerca volvulus. Infections are chronic, and persistence of the parasites for several years argues for highly adapted mechanisms of immune evasion. Due to the restricted host repertoire of O. volvulus, we have used the cattle parasite Onchocerca ochengi to investigate the nature of immunomodulation underpinning these long-term infections. Cattle were infected with a single inoculation of 350 infective-stage larvae under laboratory conditions (n = 6). Intradermal nodules containing immature adult worms were detected from 110 days postinfection, and microfilariae in skin were detected from day 280 postinfection. Parasite-specific responses during early infection were nonpolarized with respect to the major Th cytokines (interleukin-4 [IL-4], IL-2, and gamma interferon [IFN-gamma]) produced by antigen-stimulated peripheral blood mononuclear cells (PBMC) or serum antibody isotypes. Antigen-induced proliferation of PBMC peaked shortly after exposure and remained high during the prepatent infection. As the parasites matured and animals developed patent infections, there was a profound down-regulation of lymphoproliferation, accompanied by sharp falls in the expression of both IL-4 and IFN-gamma and a gradual decline in IL-2. Levels of immunoglobulin G2 (IgG2) fell, while those of IgG1 remained high. We conclude that neither a classical Th2 response nor a simple Th1-to-Th2 switch is sufficient to explain the immunomodulation associated with patent Onchocerca infections. Instead, there is an initial Th0 response, which matures into a response with some, but not all of the features of a Th2 response. The natural host-parasite relationship of O. ochengi in cattle may be useful as both a descriptive and predictive tool to test more refined models of immunomodulation in onchocerciasis.

Proinflammatory cytokine expression by Theileria annulata infected cell lines correlates with the pathology they cause in vivo.

Control of Theileria annulata is currently best achieved by the use of live attenuated cell line vaccines. However, the mechanisms underlying attenuation are unclear and there is a need to rapidly produce new cell line vaccines, which could safely and effectively vaccinate cattle against tropical theileriosis. There is increasing evidence to suggest that proinflammatory cytokines produced by T. annulata infected cells play a central role in both pathology and immune evasion. This study aimed to test this hypothesis and to evaluate cytokine expression as a marker of virulence. The pathogenicity and protective efficacy of cloned T. annulata cell lines that expressed different levels of proinflammatory cytokines were compared. In two independent trials using different stocks of T. annulata, cell lines that expressed higher levels of proinflammatory cytokines induced severe reactions, and in some cases death, when used to vaccinate groups of cattle. In contrast, low cytokine expressing lines induced low post-vaccinal reactions. The results clearly demonstrated that cytokine expression by T. annulata infected cells could be used as a marker of virulence and provided strong evidence to support a role for cytokines in the induction of pathology. Both high and low cytokine expressing cell lines protected cattle against heterologous challenge infection, offering the possibility of using cytokine expression to rapidly select new safe, potent vaccines against tropical theileriosis without the need for culture attenuation.

Anticoagulation and heart failure.

There are no clear data regarding whether to use warfarin, aspirin, or no therapy in patients with left ventricular systolic dysfunction. Aspirin use is widespread in patients with vascular disease but it can decrease renal blood flow in low output states. Warfarin may be used in patients with advancing heart failure due to the perceived risk of in situ thromboembolism. However, we know that ejection fraction and symptom class do not always match and that the regulation of warfarin dosing is more difficult in worsening heart failure. Drug use must be individualized, based on knowledge of underlying heart failure etiology, functional class, drug side effects, and renal function. We await ongoing studies to elucidate the differential effects of these drugs on global outcome as well as on the mechanisms by which they achieve their results.

Distinct response kinetics of gamma interferon and interleukin-4 in bovine tuberculosis.

This study shows that gamma interferon (IFN-gamma) and interleukin-4 (IL-4) cytokine responses are produced by peripheral blood cells in cattle infected with Mycobacterium bovis. The different kinetics of the IFN-gamma and IL-4 responses to bovine tuberculin and to ESAT-6 following experimental intratracheal infection with M. bovis are described. An early increase in IFN-gamma was observed that was maintained throughout the period studied. In contrast, the IL-4 response was delayed and confined to a peak of activity lasting 6 to 8 weeks. Interestingly, an experimental challenge of cattle with a lower dose of M. bovis which did not result in the development of lesions, positive DTH skin test, or substantial IFN-gamma responses nevertheless generated strong specific IL-4 responses. Investigation of naturally infected M. bovis field reactors showed increased IFN-gamma and IL-4 responses compared to uninfected cattle and that both of these cytokines were equally able to differentiate infected from uninfected animals. The magnitude of the M. bovis-induced IL-4 responses were found to be similar to the antigen-specific IL-4 responses of cattle infected with the parasitic nematode Onchocerca ochengi, further supporting the presence of this type 2 cytokine in bovine tuberculosis.

Onchocerca volvulus: comparative analysis of antibody responses to recombinant antigens in two animal models of onchocerciasis.

Experimental infections of chimpanzees with Onchocerca volvulus and cattle with Onchocerca ochengi provide model systems for research in human onchocerciasis. These infections share many similarities from the standpoint of parasite biology, but little is known about the comparability of immune responses in the two systems. To make a direct comparison between the models in terms of immune responsiveness to defined parasite products, three recombinant antigens of O. volvulus (Ov7, Ov103, and B20) were used to analyze the kinetics of antibody production following experimental infection. Each of the antigens was derived from adult cDNA libraries following immunoscreening with sera from chimpanzees (Ov7, Ov103) or cattle (B20). All chimpanzees (n = 12) and cattle (n = 8) displayed responses to Ov7 and Ov103, and all cattle, but only 33% of chimpanzees, showed responses to B20. The dynamics of the response to individual antigens showed further similarities between the chimpanzees and the cattle, with responses to Ov7 and Ov103 peaking after, and B20 before, the onset of patent infections. We conclude that there is good preliminary evidence of concordance in the kinetics of serological responses in the two models. However, individual antigens many be more or less immunogenic in the two systems, making it inadvisable to extrapolate between models concerning the relative immunodominance of specific parasite products.

Onchocerca ochengi infections in cattle as a model for human onchocerciasis: recent developments.

The bovine parasite Onchocerca ochengi is a nodule-dwelling filarial nematode, closely related to O. volvulus, the causal agent of human River Blindness, and, sharing with it, the same vector. This brief review, based on a presentation at the BSP Autumn Symposium 1999, describes recent work supported by the WHO Drug Development Research Macrofil programme and the Edna McConnell Clark Foundation vaccine development programme, to research the chemotherapy and immunology of onchocerciasis utilising this model system, with experimental infections in Liverpool and field infections in northern Cameroon. In a series of chemotherapeutic trials involving 10 compounds in 20 treatment regimes, the comparability of drug efficacy against O. ochengi with that described against O. volvulus has been demonstrated. Repeated, long-term treatment with oxytetracycline has been shown to be macrofilaricidal and the effect is hypothesized to be related to action on Wolbachia endobacteria, abundant in O. ochengi. Avermectins/milbemycins are not macrofilaricidal (even in high and repeated long-term treatments) but induce sustained abrogation of embryogenesis. In prospective, field exposure experiments with naive calves, prophylactic treatments with ivermectin and moxidectin prevented the development of adult worm infection, raising the possibility that drug-attenuated larval challenge infections may induce immunity. Putatively immune adult cattle exist in endemically exposed populations, and these have been shown to be significantly less susceptible to challenge than age-matched naive controls, whereas radically drug-cured, previously patently-infected cattle were not. Experimental infections with O. ochengi have revealed the kinetics of the immune response in relation to parasite development and demonstrate analogous responses to those reported in O. volvulus infection in humans and chimpanzees. In an immunization experiment with irradiated L3 larvae, cattle were significantly protected against experimental challenge--the first such demonstration of the experimental induction of immunity in a natural Onchocerca host-parasite system. Taken collectively, these studies not only demonstrate the similarity between the host-parasite relationships of O. ochengi in cattle and O. volvulus in humans, but promise to advance options for the control of human onchocerciasis.

Patterns of Onchocerca volvulus recombinant antigen recognition in a bovine model of onchocerciasis.

The antibody responses of 8 cattle experimentally infected with Onchocerca ochengi to 18 recombinant O. volvulus antigens were measured by ELISA. In addition to establishing antigenic cross-reactivity between the species, the dynamics of antigen-specific responses were examined to assess how the recognition of the antigens compared to the known stage-specificity of expression. Six cattle responded to all of the antigens and 2 animals responded to all but 1. The dynamics of the recognition of 4 antigens (B20, MOv-2, MOv-14 and OvNHR2 02E1) were characterized by rapid seroconversion following infection. Antibody levels to 2 antigens (Ov7 and OvALT-1) increased gradually over the course of infection. Antibody levels to 4 antigens (OvTPX-2, OvL3Chitinase, Ov103 and Ov9m) reached maximum levels coincident with the onset of patency. The levels to 3 antigens (OvProalf C50, OvAldolase, Ov39) varied little over the course of infection. Responses to antigens with functional similarities (OvSOD1, OvSOD2 and OvSOD3 or OvGST1 and OvGST2) showed comparable temporal profiles. This study demonstrates the high degree of immunological cross-reactivity between the antigens of O. volvulus and O. ochengi. The immunogenicity of antigens varied over the course of infection in an antigen-specific manner, which not always reflected developmentally regulated expression of the corresponding gene, possibly owing to cross-reactive epitopes on distinct parasite products.

Comparison of long-term patency of "horseshoe" saphenous vein grafts with and without valves.

OBJECTIVE: The paper analyzes the long-term patency of valveless and valvular limbs of reversed saphenous veins. METHODS: Between 1983 and 1988, 335 patients underwent isolated coronary artery bypass grafting (CABG) with 1,329 grafts. Eighty-three patients had follow-up angiography over 8-12 years. The side-to-side saphenous vein to aortic "horseshoe" anastomosis was created just before the first valve from the ankle (naturally a valveless portion). The valveless (ankle end) was depicted in every case. These patients with angiography were similar to 252 patients without angiography in terms of age, gender, number of grafts, diseases vessels, single (A) and sequential (B) grafts and actuarial survival. In the 83 patients, graft patency was 75%. Overall patency was the same in B versus A grafts (76% versus 74.6%); valveless patency (78.7%) was slightly better than valvular patency (73.3%). RESULTS: In patients with B grafts (88.6%) valveless patency was significantly better than valvular patency (71.9%) (P < 0.02). The patency of B-valveless to the left coronary bed was also better, (86.8% versus B-valvular 70.5%, P < 0.04). Attrition of the B-valveless and B-valvular grafts was similar up to 8 years, but by the 12th year it had become significantly different (P < 0.05). The 12-year actuarial survival rate of the patients was 87.7%. CONCLUSIONS: We recommended the use of valveless vein segments when possible.

Recombinant ovine interferon gamma inhibits the multiplication of Chlamydia psittaci in ovine cells.

The local production of interferon-gamma (IFN-gamma) in sheep in response to Chlamydia psittaci was measured by cannulation of the efferent lymph duct draining the site of challenge inoculation. Peak production of IFN-gamma (256 U/ml) was detected 24 h after challenge. Based on these physiological data, functional studies were carried out in vitro to determine the effect of recombinant ovine (rOv) IFN-gamma on the multiplication of C. psittaci in ovine fibroblasts. IFN-gamma inhibited the multiplication of C. psittaci in ovine cells over a range of concentrations (250 U/ml to 2.5 U/ml) in a dose-dependent manner. The inhibition of chlamydial multiplication was most pronounced when cells were treated with rOvIFN-gamma for 24 h before infection. The addition of exogenous L-tryptophan (500 micrograms/ml) to cultures within 48th of infection abrogated the anti-chlamydial effect of rOvIFN-gamma thus suggesting that tryptophan deprivation is an anti-chlamydial mechanism induced by rOvIFN-gamma in these ovine cells.

Comparison of angiographic findings and demographic variables in patients with coronary artery disease presenting with acute pulmonary edema versus those presenting with chest pain.

One hundred nineteen patients admitted to the coronary care unit with pulmonary edema were retrospectively reviewed to identify the demographic characteristics and underlying cardiac disorders of this population. The patients with pulmonary edema were compared with 119 patients admitted to the coronary care unit with chest pain. Cardiac catheterization in 71 patients with pulmonary edema and 93 with chest pain showed left main and 3-vessel coronary artery diseases to be equally common in both groups, although anginal pain was infrequent in patients with pulmonary edema (n = 28, 24%). Left ventricular function was reduced in the patients with pulmonary edema compared with those with chest pain (mean ejection fraction 42 vs 59%; p less than 0.001). More patients with pulmonary edema were black, and had diabetes and preexisting hypertension than those with chest pain. The results of cardiac catheterization were the same for black and white patients with pulmonary edema. In conclusion, patients with pulmonary edema have a high incidence of cardiac disease, and pulmonary edema may be 1 manifestation of silent myocardial ischemia. Important demographic differences exist between patients admitted with pulmonary edema and those who present with chest pain.

Percutaneous intravascular ultrasound imaging: validation of a real-time synthetic aperture array catheter.

This study was designed to validate the dimensional accuracy and ability to characterize atherosclerotic vessel morphology of a new percutaneously passed ultrasound catheter. The 5.5F catheter used for this study has a synthetic aperture array transducer providing a radial field of view perpendicular to the catheter and can be passed over a standard 0.014-in guide wire. Initial in vitro studies were performed to assess accuracy of dimensional and morphologic information. In vitro images of fixed human vessels demonstrated good boundary definition, and dimensional measurements were closely correlated with histological samples (luminal area, r = .97; maximal lumen diameter, r = .95; maximal wall thickness, r = .83). Morphological subtypes were also closely correlated, with increasing severity of histological atherosclerosis characterized by predictable changes in the ultrasound images. Subsequently, the catheter was passed percutaneously in 28 patients to obtain images of coronary (n = 20) and pelvic (n = 12) vessels. Ultrasound images were compared with simultaneous digital angiograms. Correlation between ultrasonic and angiographic estimations of vessel diameters was good (r = .92). We conclude that intravascular ultrasound imaging will be useful for dimensional and morphological characterization of vascular disease, for the study of regression or progression of atherosclerosis, and, potentially, for guidance of therapeutic interventions such as atherectomy and angioplasty.

Percutaneous intracoronary ultrasound imaging: initial applications in patients.

This study was designed to evaluate the feasibility and potential clinical utility of intracoronary ultrasound imaging in patients using a 5.5 F synthetic aperture array, over-a-wire ultrasound catheter. Thirty patients underwent percutaneous intracoronary (n = 22) or peripheral (n = 8) ultrasound imaging at the time of cardiac catheterization. Ultrasound images were compared to simultaneous digital angiograms. Correlation between ultrasonic and angiographic estimation of coronary diameters was good (r = 0.80). Morphological analysis of ultrasound images obtained in patients revealed a pattern consistent with mild-to-minimal atherosclerosis, as defined by prior in vitro studies. In 15 patients, imaging was performed during intracoronary infusion of vasoactive medications (papaverine 15 mg, nitroglycerine 100 mugm, and acetylcholine 2 x 10 -5 or 2 x 10 -6M). These medications were also infused during continuous intracoronary Doppler catheter monitoring of velocity and pressure, thus allowing calculation of volume flow and coronary resistance indices. Serial determination of ultrasound-derived epicardial vessel cross-sectional area demonstrated no change (-1 +/- 1%) after papaverine, an 8 +/- 2% increase after nitroglycerine, and a 9 +/- 3% decrease after acetylcholine. Calculated resistance fell 53 +/- 4% after acetylcholine and 60 +/- 3% after papaverine. Preliminary in vitro studies using a combination angioplasty balloon/ultrasound catheter demonstrated the ability to visualize vessel dilation in real time. We conclude that intravascular ultrasound imaging will be useful for dimensional and morphological characterization of vascular disease, for beat-to-beat monitoring of vasomotion, and potentially as a real-time adjunct to therapeutic interventions.

Estimation of coronary flow reserve by intracoronary Doppler flow probes and digital angiography.

This prospective study investigated two different methods used clinically to estimate coronary flow reserve during cardiac catheterization. First, the relationship between simultaneous digital angiography and intracoronary Doppler velocity measurements was determined in 61 patients. The correlation coefficient for 233 simultaneous pairs of papaverine-induced flow reserve was 0.70 (Doppler = 0.41 digital + 0.93, P less than 0.0001). Repeated basal flow determinations showed little variability (Doppler: 2 +/- 5% (mean +/- 95% confidence intervals); digital: 3 +/- 10%). Repeated hyperemic flow estimates by the Doppler technique were more reproducible (10 +/- 2%) than those by the digital method (26 +/- 6%). Second, estimates of coronary flow reserve by side-mounted and end-mounted Doppler catheters were compared in vitro and in patients. In vitro measurement of blood velocity was linear for both catheter designs and was highly correlated with volume flow determined by electromagnetic flow meter (r = 0.99 side-mounted; r = 0.96 end-mounted). In patients (n = 20), average coronary flow reserve for the side-mounted Doppler crystal was 2.64 +/- 0.15 and for the end-mounted Doppler crystal was 2.40 +/- 0.14 (P less than 0.02). When flow reserve was determined twice for each catheter, there was greater variability in repeated measurements using the side-mounted Doppler crystal (21 +/- 10%, n = 14) than using the end-mounted Doppler crystal (12 +/- 4%, n = 32).(ABSTRACT TRUNCATED AT 250 WORDS)