Morphological and clinical implications of the optical coherence tomography-derived lipid core burden index

Background

Intracoronary optical coherence tomography (OCT) is a valuable tool for vulnerable plaque assessment and morphology-guided risk stratification. However the groundbreaking impact of OCT in clinical practice may be offset by its inherent limitation, the subjectivity in plaque interpretation. Recent studies reported a semi-automated method to assess fibrous cap thickness but data regarding an automated assessment of lipid component at OCT, such a lipid core burden index (LCBI), are lacking.

Purpose

The aim of this study was to assess the morphological characteristics and prognostic implications of an OCT-derived LCBI (OCT-LCBI).

Methods

In order to assess OCT-LCBI in 1003 patients with 1-year follow-up from the CLIMA multicenter registry (clinicaltrial.gov identifier NCT02883088) we used a novel previously validated software able to automate obtain a maximum OCT-LCBI in 4 mm (maxOCT-LCBI4mm). A maxOCT-LCBI4mm cut-off of 400 was used, based on previous literature on this topic. Primary composite clinical endpoint included cardiac death, myocardial infarction and target vessel revascularization. A secondary analysis using clinical outcomes of CLIMA study was performed.

Results

Patients with a maxOCT-LCBI4mm ≥400 showed higher prevalence of fibrous cap thickness <75μm (FCT, odds ratio [OR] 1.43, 95% confidence interval [CI] 1.03–1.99; p=0.034), lipid pool arc >180°(OR 3.93, 95% CI 2.97–5.21; p<0.001), minimum lumen area <3.5 mm2 (OR 1.5, 1.16–1.94; p=0.002), macrophage infiltration (OR 2.38, 95% CI 1.81–3.13; p<0.001) and intra-plaque intimal vasculature (OR 1.34, 95% CI 1.05–1.72, p=0.021). A maxOCT-LCBI4mm ≥400 predicted the primary endpoint (adjusted hazard ratio [HR] 1.86, 95% CI 1.1–3.2; p=0.019) as well as the CLIMA endpoint (HR 2.56, 95% CI 1.24–5.29; p=0.011). Patients with high lipid content and thin FCT <75 μm were at higher risk for adverse events (HR 4.88, 95% CI 2.44–9.72; p<0.001) (Figure 1).

Conclusions

We applied for the first time in a large population with clinical follow-up a software able to automatically obtain a maxOCT-LCBI4mm. A high maxOCT-LCBI4mm was related to vulnerable plaque features and further clinical events. This study represents a step further towards a comprehensive automated assessment of the coronary plaque risk profile.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Supported by a grant from the Centro per la Lotta contro l'Infarto – Fondazione Onlus, Rome, Italy

P388 CORONARY PLAQUE CHARACTERISTICS ASSOCIATED WITH MAJOR ADVERSE CARDIOVASCULAR EVENTS AMONG ATHEROSCLEROTIC PATIENTS AND LESIONS: A SYSTEMATIC REVIEW AND META–ANALYSIS

Background

The clinical value of coronary plaque characteristics (CPCs) to inform intensified medical therapy or revascularization of non–flow–limiting lesion remains uncertain. We performed a systematic review and meta–analysis to study the prognostic impact of CPCs comprehensively assessed with invasive and non–invasive imaging technologies on patient–level and lesion–level major cardiovascular adverse events (MACE).

Methods

We systematically reviewed MEDLINE, EMBASE, and the Cochrane database for studies evaluating the association of CPC with patient–level and lesion–level (MACE). CPCs included high plaque burden, low minimal lumen area, thin cap fibroatheroma, high lipid core burden index, low attenuation plaque, spotty calcification, napkin ring sign or positive remodelling.

Results

Thirty studies (21 retrospective, 9 prospective) with 30.369 patients were included. CPCs were evaluated by invasive intravascular techniques in 9 studies (optical coherence tomography=4, intravascular ultrasound imaging=3, near–infrared spectroscopy intravascular ultrasound imaging=2) and by coronary computed tomography angiography (CCTA) in 21 studies. CPCs were significantly predictive of patient–level and lesion–level MACE, also when only adjusted data where considered. For each CPC, the odds appeared higher for lesion–level (HR range 3.2–16.8) as compared to patient–level MACE (HR range 1.8–4.1). Accuracy was modest to moderate for most CPCs at the patient–level (AUC for MACE ranging between 0.53 and 0.84) and moderate to good for most CPCs at the lesion–level (AUC for MACE ranging between 0.71 and 0.83). Plaques with more than one CPC had the highest accuracy for lesion–level MACE (AUC 0.87, 95%CI 0.84–0.90). CPC pooled sensitivities for lesion–level MACE ranged between 40% and 63% and specificities between 73% and 98%. As the pooled prevalence of CPCs among plaques was low (3% to 28%), the estimated positive predictive values for lesion–level MACE were modest (range 33% to 45%).

Conclusion

CCTA and intravascular imaging characterization of CPCs provides independent prognostic value among atherosclerotic patients and lesions. However, the modest sensitivity and positive predictive value observed across all CPCs seem to suggest modest clinical value, especially to predict lesion–level events (PROSPERO identifier: CRD42021251810).

Excimer laser technology in percutaneous coronary interventions: Cardiovascular laser society's position paper

Excimer Laser Coronary Atherectomy (ELCA) is a well-established therapy that emerged for the treatment of peripheral vascular atherosclerosis in the late 1980s, at a time when catheters and materials were rudimentary and associated with the most serious complications. Refinements in catheter technology and the introduction of improved laser techniques have led to their effective use for the treatment of a wide spectrum of complex coronary lesions, such as thrombotic lesions, severe calcific lesions, non-crossable or non-expandable lesions, chronic occlusions, and stent under-expansion. The gradual introduction of high-energy strategies combined with the contrast infusion technique has enabled us to treat an increasing number of complex cases with a low rate of periprocedural complications. Currently, the use of the ELCA has also been demonstrated to be effective in acute coronary syndrome (ACS), especially in the context of large thrombotic lesions.

Adoption of a new automated optical coherence tomography software to obtain a lipid plaque spread-out plot

Background

Near infrared spectroscopy – intravascular ultrasound (NIRS-IVUS) imaging can provide a fully automated estimation of lipid burden, providing a two-dimensional spread-out plot, the Lipid Core Burden Index (LCBI), which has been associated with higher incidence of cardiac events. Optical coherence tomography (OCT) can identify lipid component with high accuracy and it is therefore potentially capable of measuring its longitudinal extension in a dedicated two-dimensional LCBI spread-out plot.

Purpose

The present study has been designed to validate a novel automated approach to assess OCT images, able of providing a dedicated LCBI spread-out plot plus other features of plaque vulnerability.

Methods

We compared the results obtained with a novel automated OCT alghorithm, developed utilising a convolutional neural network, with those obtained with conventional (manual) OCT and with NIRS-IVUS in a consecutive series of 40 patients with coronary artery disease. We tested and validated our new OCT algorithm to calculate the lipid core longitudinal extension in a dedicated two-dimensional LCBI spread-out plot. In each coronary plaque, the following measurements were obtained with NIRS-IVUS: 1) minimum lumen area (MLA), 2) vessel area at MLA site, 3) plaque burden (%) at MLA site, 4) NIRS-defined lipid pool arch and 5) maximum LCBI measurement within a 4 mm length. The following OCT features were obtained: 1) the MLA cross section, 2) the minimum fibrous cap thickness (FCT) in presence of lipid components and measured as the average of three measurements obtained in the same cross-section and 3) maximum LCBI within a 4 mm length.

Results

Three lesions groups were identified according to the studied lesions: 1) culprit lesions in patients with acute coronary syndrome (ACS, n=16), 2) non-culprit lesions in patients with ACS (n=12) and 3) lesions in patients with stable angina (n=12). OCT conventional assessment showed for the culprit ACS plaques a trend for a larger lipid arc and a significant thinner FCT (p=0.028). Consistently, NIRS-IVUS showed for culprit ACS plaques a more complex anatomy. A strong trend for increased maximum LPBI in 4mm segments was found in the culprit ACS group, regardless of the adopted imaging modality, either NIRS-IVUS or automated OCT (p=0.184 and p=0.066, respectively, figure 1). A fair correlation was obtained for the maximum 4 mm LCBI measured by NIRS-IVUS and automated OCT (r=0.75). The sensitivity and specificity of automated OCT to detect significant LCBI, applying a validated 400 cut off were 90.5 and 84.2 respectively.

Conclusions

We developed an automated approach, comparable to NIRS, to assess OCT images that can provide a dedicated lipid plaque spread-out plot to address plaque vulnerability. The automated OCT software can promote and improve OCT clinical applications for the identification of patients at risk of hard events.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): CLI - Centro Lotta all'Infarto Spread-out plot by IVUS-NIRS and OCT

Unifying Frequency Combs in Active and Passive Cavities: Temporal Solitons in Externally Driven Ring Lasers

Frequency combs have become a prominent research area in optics. Of particular interest as integrated comb technology are chip-scale sources, such as semiconductor lasers and microresonators, which consist of resonators embedding a nonlinear medium either with or without population inversion. Such active and passive cavities were so far treated distinctly. Here we propose a formal unification by introducing a general equation that describes both types of cavities. The equation also captures the physics of a hybrid device-a semiconductor ring laser with an external optical drive-in which we show the existence of temporal solitons, previously identified only in microresonators, thanks to symmetry breaking and self-localization phenomena typical of spatially extended dissipative systems.

P5539Genetic heterogeneity of spontaneous coronary artery dissection (SCAD)

Introduction

SCAD is a rare coronary event that may cause acute coronary syndromes (ACS). SCAD predominantly occurs in apparently healthy, young to middle aged women (up to 95% of cases). The known causes include: heritable connective tissue diseases, fibromuscular dysplasia, arteritis, contraceptives, cocaine abuse and chest trauma. A variable proportion of patients manifests progression to longer segments of the same vessel or recurrence of dissection in other coronary arteries. SCAD can be the first manifestation of a previously unrecognised systemic disease.

Methods

In 2010 we started collecting consecutive SCAD, as first clinical manifestation, in patients addressed to our attention for investigation of genetic or non genetic causes, after successful management of the acute phase and exclusion of systemic inflammatory and autoimmune diseases. All patients underwent genetic visit and counselling, collection of clinical reports and imaging records, clinical cardiologic evaluation with pan-angio CT scan, biochemical testing including coagulation-related tests, and and genetic testing of genes causing connective tissue diseases. Parallel clinical family screening and genetic testing were systematically performed.

Results

The series is constituted of 35 patients (28F and 7M) (age at onset, mean ± SD, 44±7.6 years) with ACS-SCAD (20 STEMI and 15 NSTEMI) and 9 second dissections in a different coronary artery. Two sisters had ACS-SCAD caused by dissection of the same coronary artery.

We identified pathologic mutations (n=19/35, 54%) in COL3A1 (n=3), FBN1 (n=1), FBN1+TGFBR1 (n=1), TGFBR1 (n=2), TGFBR2 (n=1), MYLK (n=1), SMAD3 (n=1), COL5A1 (n=1 homozygous), COL5A2 (n=1), MYH11 (n=1), TGFB2 (n=1), ABCC6 (1 homozygous), ELN (2 homozygous sisters and 1 heterozygous unrelated patient), NOTCH1 (n=1). In 8 (23%) patients we identified VUS classified as C3 because previously unreported and predicted as uncertain on the basis of in silico analyses. In the remaining 8 patients we only identified C2 variants. A second SCAD (14 days to 78 months after the first event) occurred in 9 patients (9/35, 25%) (COL3A1 (n=2), FBN1 (n=1), FBN1+TGFBR1 (n=1), MYLK (n=1), COL5A2 (n=1), NOTCH1 (n=1) COL5A2 (n=1) and 1 with a C2 variant in COL3A1. Two patients with thrombocytosis were carriers of the somatic JAK2 V617F mutation. Extra-coronary arterial dilations/aneurysms occurred in 13 families; in the follow-up 2 patients demonstrate dissection in non-coronary arteries.

Conclusions

Our series, with the potential bias of a referral centre for inherited cardiovascular disease, demonstrated that SCAD is the possible first manifestation of a genetic disorder and that neither disease gene or mutation predicts the risk of a second coronary event. SCAD is a potentially fatal coronary event associated with ACS, warning for familial disease and unpredictable risk of recurrence.

From the Lugiato-Lefever equation to microresonator-based soliton Kerr frequency combs

The model, that is usually called the Lugiato-Lefever equation (LLE), was introduced in 1987 with the aim of providing a paradigm for dissipative structure and pattern formation in nonlinear optics. This model, describing a driven, detuned and damped nonlinear Schroedinger equation, gives rise to dissipative spatial and temporal solitons. Recently, the rather idealized conditions, assumed in the LLE, have materialized in the form of continuous wave driven optical microresonators, with the discovery of temporal dissipative Kerr solitons (DKS). These experiments have revealed that the LLE is a perfect and exact description of Kerr frequency combs-first observed in 2007, i.e. 20 years after the original formulation of the LLE-and in particular describe soliton states. Observed to spontaneously form in Kerr frequency combs in crystalline microresonators in 2013, such DKS are preferred state of operation, offering coherent and broadband optical frequency combs, whose bandwidth can be extended exploiting soliton-induced broadening phenomena. Combined with the ability to miniaturize and integrate on-chip, microresonator-based soliton Kerr frequency combs have already found applications in self-referenced frequency combs, dual-comb spectroscopy, frequency synthesis, low noise microwave generation, laser frequency ranging, and astrophysical spectrometer calibration, and have the potential to make comb technology ubiquitous. As such, pattern formation in driven, dissipative nonlinear optical systems is becoming the central Physics of soliton micro-comb technology.This article is part of the theme issue 'Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 2)'.

Characterization of antibody response in neuroinvasive infection caused by Toscana virus

OBJECTIVES

Among sandfly-borne pathogens, Toscana virus (TOSV) is a prominent cause of summer meningitis in Mediterranean Europe. Here, we assessed the kinetics of anti-TOSV antibodies over time in 41 patients diagnosed with TOSV meningitis or meningoencephalitis in northeastern Italy.

METHODS

Acute and follow-up serum samples were collected up to 20 months after diagnosis of TOSV infection and tested for the presence of specific antibody using immunoenzymatic and indirect immunofluorescence assays. In addition, maturation of anti-TOSV IgG over time was evaluated as well as production of neutralizing antibodies.

RESULTS

Specific IgM and IgG response was present at diagnosis in 100% of patients; TOSV-specific IgM and IgG were detected in patients' sera up to 6 and 20 months after diagnosis, respectively. The avidity index (AI) increased over the first month after infection in 100% of patients and most cases exceeded 60% by Day 30 post infection. The AI subsequently plateaued then declined at 20 months after diagnosis. Finally, neutralization assay to TOSV was performed in 217 sera collected from 41 patients; 69.6% of tested samples resulted in reactive and moderate levels of neutralizing antibodies observed during all phases of infection despite high titres of total anti-TOSV IgG.

CONCLUSIONS

Specific antibody response develops rapidly and is long-lasting for neuroinvasive TOSV infection. Serodiagnosis of neuroinvasive TOSV requires simultaneous detection of specific IgM and IgG. Moderate levels of neutralizing antibodies were maintained over the study period, while the protective role of antibodies lacking neutralizing activity is unclear and requires further evaluation.

Publisher's Note: Refractory period of an excitable semiconductor laser with optical injection [Phys. Rev. E 95, 012214 (2017)]

This corrects the article DOI: 10.1103/PhysRevE.95.012214.

Refractory period of an excitable semiconductor laser with optical injection

Injection-locked semiconductor lasers can be brought to a neuronlike excitable regime when parameters are set close to the unlocking transition. Here we study experimentally the response of this system to repeated optical perturbations and observe the existence of a refractory period during which perturbations are not able to elicit an excitable response. The results are analyzed via simulations of a set of dynamical equations which reproduced adequately the experimental results.

Transmission of HIV Drug Resistance and the Predicted Effect on Current First-line Regimens in Europe

Transmitted human immunodeficiency virus drug resistance in Europe is stable at around 8%. The impact of baseline mutation patterns on susceptibility to antiretroviral drugs should be addressed using clinical guidelines. The impact on baseline susceptibility is largest for nonnucleoside reverse transcriptase inhibitors.

Background. Numerous studies have shown that baseline drug resistance patterns may influence the outcome of antiretroviral therapy. Therefore, guidelines recommend drug resistance testing to guide the choice of initial regimen. In addition to optimizing individual patient management, these baseline resistance data enable transmitted drug resistance (TDR) to be surveyed for public health purposes. The SPREAD program systematically collects data to gain insight into TDR occurring in Europe since 2001.

Methods. Demographic, clinical, and virological data from 4140 antiretroviral-naive human immunodeficiency virus (HIV)–infected individuals from 26 countries who were newly diagnosed between 2008 and 2010 were analyzed. Evidence of TDR was defined using the WHO list for surveillance of drug resistance mutations. Prevalence of TDR was assessed over time by comparing the results to SPREAD data from 2002 to 2007. Baseline susceptibility to antiretroviral drugs was predicted using the Stanford HIVdb program version 7.0.

Results. The overall prevalence of TDR did not change significantly over time and was 8.3% (95% confidence interval, 7.2%–9.5%) in 2008–2010. The most frequent indicators of TDR were nucleoside reverse transcriptase inhibitor (NRTI) mutations (4.5%), followed by nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations (2.9%) and protease inhibitor mutations (2.0%). Baseline mutations were most predictive of reduced susceptibility to initial NNRTI-based regimens: 4.5% and 6.5% of patient isolates were predicted to have resistance to regimens containing efavirenz or rilpivirine, respectively, independent of current NRTI backbones.

Conclusions. Although TDR was highest for NRTIs, the impact of baseline drug resistance patterns on susceptibility was largest for NNRTIs. The prevalence of TDR assessed by epidemiological surveys does not clearly indicate to what degree susceptibility to different drug classes is affected.

Dissipative Phase Solitons in Semiconductor Lasers

We experimentally demonstrate the existence of nondispersive solitary waves associated with a 2π phase rotation in a strongly multimode ring semiconductor laser with coherent forcing. Similarly to Bloch domain walls, such structures host a chiral charge. The numerical simulations based on a set of effective Maxwell-Bloch equations support the experimental evidence that only one sign of chiral charge is stable, which strongly affects the motion of the phase solitons. Furthermore, the reduction of the model to a modified Ginzburg-Landau equation with forcing demonstrates the generality of these phenomena and exposes the impact of the lack of parity symmetry in propagative optical systems.

Observation of electro-activated localized structures in broad area VCSELs

We demonstrate experimentally the electro-activation of a localized optical structure in a coherently driven broad-area vertical-cavity surface-emitting laser (VCSEL) operated below threshold. Control is achieved by electro-optically steering a writing beam through a pre-programmable switch based on a photorefractive funnel waveguide.

Periodic and chaotic solitons in a semiconductor laser with saturable absorber

In a semiconductor laser with saturable absorber, solitons may spontaneously drift and/or oscillate. We study three different regimes characterized by strong intensity oscillations, both periodic and chaotic. We show that (i) soliton dynamics may be similar to that of passively Q-switched lasers, (ii) solitons may drift and oscillate simultaneously, and (iii) chaotic solitons may coexist with stationary ones and with the laser off solution.

A concomitant and complete set of nonvolatile all-optical logic gates based on hybrid spatial solitons

We theoretically demonstrate the realization of a complete canonical set of all-optical logic gates (AND, OR, NOT), with a persistent (stored) output, by combining propagative spatial solitons in a photorefractive crystal and dissipative cavity solitons in a downstream broad-area vertical cavity surface emitting laser (VCSEL). The system uses same-color, optical-axis aligned input and output channels with fixed readout locations, while switching from one gate to another is achieved by simply varying the potential applied to the photorefractive crystal. The inputs are Gaussian beams launched in the photorefractive crystal and the output is a bistable, persistent soliton in the VCSEL with a 'robust' eye diagram and large signal-to-noise ratio (SNR). Fast switching and intrinsic parallelism suggest that high bit flow rates can be obtained.

Two diseases, one approach: multitarget drug discovery in Alzheimer's and neglected tropical diseases

Multitarget drug discovery may represent a promising therapeutic approach to treat Alzheimer's and neglected tropical diseases.

3D reconstruction of coronary arteries using frequency domain optical coherence tomography images and biplane angiography

The aim of this study is to describe a new method for three-dimensional (3D) reconstruction of coronary arteries using Frequency Domain Optical Coherence Tomography (FD-OCT) images. The rationale is to fuse the information about the curvature of the artery, derived from biplane angiographies, with the information regarding the lumen wall, which is produced from the FD-OCT examination. The method is based on a three step approach. In the first step the lumen borders in FD-OCT images are detected. In the second step a 3D curve is produced using the center line of the vessel from the two biplane projections. Finally in the third step the detected lumen borders are placed perpendicularly onto the path based on the centroid of each lumen border. The result is a 3D reconstructed artery produced by all the lumen borders of the FD-OCT pullback representing the 3D arterial geometry of the vessel.

Atherosclerotic plaque characterization in Optical Coherence Tomography images

Optical Coherence Tomography (OCT) is a fiber--optic imaging modality which produces high resolution tomographic images of the coronary lumen and outer vessel wall. While OCT images present morphological information in highly resolved detail, the characterization of the various plaque components relies on trained readers. The aim of this study is to extract a set of features in grayscale OCT images and to use them in order to classify the atherosclerotic plaque. Intensity and texture based features we used in order to classify the plaque in four plaque types: Calcium (C), Lipid Pool (LP), Fibrous Tissue (FT) and Mixed Plaque (MP). 50 OCT annotated images from 3 patients were used to train and test the proposed plaque characterization method. Using a Random Forests classifier overall classification accuracy 80.41% is reported.

Intracoronary optical coherence tomography, basic theory and image acquisition techniques

Optical coherence tomography (OCT) imaging is showing great potential as an alternative or complementary tool to intravascular ultrasound (IVUS) for aiding in stent procedures and future diagnosis/treatment of atherosclerosis. Here, we describe the basic theory behind OCT imaging and explain important parameters such as axial resolution, lateral resolution and sensitivity. Also, we describe several image acquisition techniques that have been adopted for OCT imaging.

Difference differential equations for a resonator with a very thin nonlinear medium

We derive from the classic Maxwell-Bloch equations a set of difference-differential equations valid, in general, when the length of the nonlinear medium in the optical cavity is much smaller than a wavelength. Such equations provide an elegant and simple framework in which the case of Fabry-Perot and ring cavity can be discussed in a unified way. We outline a complete scenario for the multimode laser instability in the Fabry-Perot case, illustrating the results for parameter values appropriate to quantum cascade lasers. Our approach can have a relevant impact also on the study of dynamical instabilities in external cavity semiconductor lasers, including multiple quantum well or quantum-dot structures.

Gram-positive bloodstream infections in liver transplant recipients: incidence, risk factors, and impact on survival

The objective of the study was to assess the incidence, risk factors, and survival of gram-positive bloodstream infections (GP-BSI(s)) among liver transplant recipients during the first year after transplantation. Between October 2000 and September 2006, 42 episodes of GP-BSI(s) occurred in 205 patients with an overall incidence of 0.20 episodes/patient. Coagulase-negative staphylococci were detected in 45.2% of cases, Enterococcus species in 42.9% (E faecalis, eight; E faecium, seven; E avium, two; E gallinarum, one) and Staphylococcus aureus in 11.9%. Retransplantation was the only independent risk factor for GP-BSI (odds ratio [OR], 0.253; 95% confidence interval (CI), 0.089 to 0.715; P = .009). Thirty-day mortality rate was 28.5% and S aureus infections were related to a poorer outcome. It is noteworthy that all the isolates of S aureus were methicillin-resistant. Ampicillin was inactive against all the strains of E faecium and 50% of E avium isolates, but active against all E faecalis and E gallinarum strains. All the isolates were glycopeptide-susceptible. No significant differences in mortality rate were observed in relation to sex, etiologies of end-stage liver disease, cytomegalovirus infection/reinfection, type of donor, rejection, or retransplantation. GP-BSI, the only independent risk factor for death (OR, 0.262; 95% CI, 0.106 to 0.643; P = .003), reduced the survival rate by 26% in the first year posttransplant. In conclusion, GP-BSI(s) impact significantly on morbidity and mortality posttransplant, particularly among retransplantations. Control measures are required to reduce the incidence of GP-BSI(s) in liver transplant recipients. These findings must be considered when empirical antimicrobial therapy is indicated while awaiting blood-culture results.

Effects of ketamine or medetomidine administration on quality of electroejaculated sperm and on sperm flow in the domestic cat

The effects of two commonly used drugs for anaesthesia in the domestic cat, ketamine and medetomidine, on features of electroejaculated semen and on sperm flow in this species were evaluated performing three experiments. This is the first study about these topics in the domestic cat. In Experiment 1, ketamine or medetomidine effects on cat sperm quality after collection by electroejaculation (E.E.) have been assessed in nine animals. Results showed that mean sperm concentration was significantly higher (p<0.01) after medetomidine than after ketamine administration. In Experiment 2, ketamine or medetomidine effects on sperm flow in 12 electroejaculated cats were studied. Mean sperm concentration and mean total number of spermatozoa resulted significantly higher (p<0.01) in medetomidine than in ketamine treated animals. The number of spermatozoa displaced in urethra was significantly higher (p<0.01) using medetomidine. No significant differences were observed in percentages of retrograde flow. In Experiment 3, ketamine or medetomidine effects on urethral sperm flow, without any stimulation for sperm collection, were evaluated. Data obtained showed a significantly higher (p<0.05) number of spermatozoa displaced in urethra after medetomidine than after ketamine injection. In conclusion, E.E. in the cat after medetomidine administration determined a higher number of spermatozoa per ejaculate than after ketamine administration, with a good pharmacological restriction and without increasing sperm retrograde flow.

Does optical coherence tomography identify arterial healing after stenting? An in vivo comparison with histology, in a rabbit carotid model

OBJECTIVE

To verify whether optical coherence tomography (OCT) can accurately monitor the occurrence of arterial healing after stenting.

SETTING

Delayed stent endothelialisation may predispose to stent thrombosis. OCT is a high-resolution intravascular imaging technique that accurately identifies stent struts and arterial tissues.

DESIGN AND INTERVENTIONS

Eight New Zealand white rabbits underwent the implantation of single bare metal stents (diameter 2-2.5 mm, length 8-13 mm) in the right common carotid artery through the external carotid artery. After a median of 11 days (range 2-28), the stented arteries were visualised by OCT, with images acquired at a pull-back speed of 0.5 mm/sec. The rabbits were then euthanised, vessels were formalin-fixed and finally processed for histopathology.

RESULTS

We analysed 32 cross-sections from eight stented carotid arteries, for a total of 384 stent struts. OCT detected all of the stent struts in 30 of 32 cross-sections (93.7%), and correctly identified the presence/absence of tissue for every strut. Histological and OCT measurements of mean neointima thickness (0.135 (SD 0.079) mm and 0.145 (SD 0.085) mm, respectively, p = NS) were similar and closely related (r = 0.85, p<0.001). Neointima area progressively increased with longer time intervals from stent deployment to sacrifice; histological and OCT measurements were similar for each time interval. The intra-observer and interobserver reproducibility of OCT neointima measurements were excellent (R2 = 0.90 and 0.88, respectively).

CONCLUSIONS

OCT is a promising means for monitoring stent strut coverage and vessel wall healing in vivo, the relevance of which will become even more significant with the increasing use of drug-eluting stents.

Ultrasonography for pregnancy diagnosis and evaluation in queens

In the present paper, we describe the clinical utility of ultrasonography for diagnosing and evaluating pregnancy in domestic cats. Ultrasonography is a non-invasive technique that permits an accurate diagnosis of pregnancy and allows serial evaluation of the developing embryo/fetus and the extrafetal structures. The first ultrasonographic indication of pregnancy is a gestational chamber seen on day 10 after mating as a small circular anechoic structure. From day 30, it is possible to recognize different fetal organs, and between 38 and 43 days, the gender of the fetus can be determined. Measurements obtained during the second half of gestation can be used to determine fetal age and calculations can then be made that may more accurately predict the time of parturition. Further studies are needed in the queen to determine the applicability of the echo-Doppler technique used routinely in human obstetric medicine. This type of ultrasonography could potentially provide useful information about fetal health and the maturity of the placenta.

Fertilizing Ability of Electro-Ejaculated Cryopreserved Semen in the Domestic Cat

Semen collection and AI in the cat are still not routine procedures. The correlation between semen quality and fertility under natural conditions is a relatively unknown field in the cat. In the present study, functional in vitro tests, such as the ability to bind and penetrate the zona pellucida or to fertilize in vitro, were used to determine fertilizing ability of sperm cryopreserved with a practical and efficient freezing protocol previously developed in our laboratory. Semen was collected by electroejaculation, evaluated for motility and diluted with Tris-glucose-citrate egg-yolk extender supplemented with Equex STM paste (0.5% v/v). After equilibration and loading into 0.25 ml straws, semen was frozen at 3.85 degrees C/min. Frozen-thawed semen was co-cultured with in vitro matured cat oocytes. Penetration rate was recorded 30 h after in vitro fertilization and cleaved zygotes were cultured in vitro until day 7. A correlation was found between sperm motility index (SMI) after thawing and semen fertilizing ability (p<0.05). In conclusion, it was demonstrated that the post-thaw motility quality, expressed as SMI, of spermatozoa frozen using the protocol mentioned above can be considered an index of the sperm ability to penetrate in vitro matured oocytes.

319IN VITRO MATURATION OF EQUINE OOCYTES IN A COMPLETELY DEFINED MEDIUM SUPPLEMENTED WITH PROGESTERONE

A completely defined medium for in vitro maturation (IVM) of equine oocytes has not yet been developed, since most of the media used for IVM are supplemented with serum or BSA. Furthermore, in this species there is no report about the influence of progesterone on maturation, although it has already been used as supplement (500ngmL−1) in EMMI (Maclellan LJ et al., 2001, Theriogenolgy 55, 310 abst). The aims of this study were to develop a completely defined medium for equine oocyte maturation and to investigate the effect of progesterone on nuclear maturation. Equine oocytes were collected by follicular scraping of abattoir-derived ovaries between April and June. The basal medium for maturation was SOFaa supplemented with pFSH-LH 0.1IUmL−1 (Pluset, Laboratorios Calier, Barcelona, Spain), EGF* 50ngmL−1, ITS (Insulin, Transferrin, Sodium selenite), L-cysteine 1.2mM, Maturation SOF (MSOF). Compact cumulus-oocyte complexes were selected, washed three times in H-SOF and matured in one of the following media (15–20 oocytesmL−1): (1) MSOF+FCS 10% (MSOF-FCS), (2) MSOF+progesterone 100ngmL−1 (MSOF-P4), (3) MSOF. After 24h of culture in 5% CO2 in air at 38.5°C, the oocytes were denuded by gently pipetting in a 0.25% trypsin solution, washed and stained with Hoechst 33258 (10μgmL−1 in PBS) for 30min at room temperature. Oocytes were examined under a fluorescent microscope to assess nuclear maturation. Only oocytes with an evident polar body and metaphase II plate (MII) were considered mature. The experiment was done in 6 replicates. Chi Square test was used for statistical analysis (Statistica for Windows – Stat Soft Inc., Tusla, OK, USA). Significance was assessed for P&lt;0.05. The results of this study show that MSOF can be considered a suitable completely defined medium for IVM of equine oocytes. Adding progesterone significantly (P&lt;0.05) increases the nuclear maturation rate at 24h of culture. It can be speculated that although cumuls cells produce this hormone, supplementation is useful to reach progesterone concentrations similar to those present in follicular fluid (early dominant 63.4±19.3ngmL−1, healthy preovulatory follicle 1094.3±170.9ngmL−1; Gerard N et al., 2002, Reproduction 124, 241–248). Further studies are needed to investigate the influence of progesterone on cytoplasmic maturation and to test the effect of different progesterone concentrations and time of maturation in a completely defined system.*All chemicals were purchased from Sigma, St. Louis, MO, USA, unless otherwise stated. Table 1 Maturation of equine oocytes in different media

Eccentric atherosclerotic plaques with positive remodelling have a pericardial distribution: a permissive role of epicardial fat? A three-dimensional intravascular ultrasound study of left anterior descending artery lesions

AIMS

The transversal distribution of coronary atherosclerotic plaques (AP) (myocardial vs pericardial) affects vessel remodelling. The aim of this study was to define the impact of transversal lesion distribution on vessel remodelling in proximal and distal coronary segments using a 3D intravascular ultrasound (IVUS) reconstruction.

METHODS

The study group included 70 lesions located in the left anterior descending artery within 5mm of the septal take-off, and imaged using 3D-IVUS. The take-off of the septal branch was used to divide the plaque into a myocardial and pericardial surface. The IVUS index of vessel remodelling was calculated as: [narrowest external elastic membrane (EEM) site cross-sectional area (CSA)-reference EEM CSA)/reference EEM CSAx100]. The lesions with an intermediate vessel remodelling index (between -25% and +15%) were excluded from analysis.

RESULTS

Of the 38 APs with a pericardial distribution, 34 (89%) showed positive remodelling (P<0.001). The distal lesions had a positive vessel remodelling index regardless of transversal plaque distribution. At multivariate analysis, pericardial distribution and the distal location of AP were the only independent variables predictive of positive remodelling.

CONCLUSIONS

The transversal distribution of atherosclerotic plaque affects vessel remodelling in left anterior descending coronary lesions, probably because of an extravascular splinting effect. Distal lesions usually show positive remodelling regardless of transversal plaque distribution.

Large intracoronary thrombi with good TIMI flow during acute myocardial infarction: four cases of successful aggressive medical management in patients without angiographically detectable coronary atherosclerosis

Four cases of young patients with acute myocardial infarction are discussed in which urgent angiography showed large intracoronary thrombus and TIMI (thrombolysis in myocardial infarction) flow > or = 2 in the infarct related artery. The rest of the coronary tree appeared to be free of detectable atherosclerosis. Percutaneous transluminal coronary angioplasty was not performed and an aggressive antiplatelet/anticoagulant treatment was administered (acetylsalicylic acid, clopidogrel, abciximab, and heparin). In all cases early angiographic control (1-12 days after AMI) showed disappearance of thrombus, no significant residual stenosis, and normal flow. No deterioration of left ventricular function was observed and the clinical course both in hospital and at five months' follow up was uneventful.

Structures of ceftazidime and its transition-state analogue in complex with AmpC beta-lactamase: implications for resistance mutations and inhibitor design

Third-generation cephalosporins are widely used beta-lactam antibiotics that resist hydrolysis by beta-lactamases. Recently, mutant beta-lactamases that rapidly inactivate these drugs have emerged. To investigate why third-generation cephalosporins are relatively stable to wild-type class C beta-lactamases and how mutant enzymes might overcome this, the structures of the class C beta-lactamase AmpC in complex with the third-generation cephalosporin ceftazidime and with a transition-state analogue of ceftazidime were determined by X-ray crystallography to 2.0 and 2.3 A resolution, respectively. Comparison of the acyl-enzyme structures of ceftazidime and loracarbef, a beta-lactam substrate, reveals that the conformation of ceftazidime in the active site differs from that of substrates. Comparison of the structures of the acyl-enzyme intermediate and the transition-state analogue suggests that ceftazidime blocks formation of the tetrahedral transition state, explaining why it is an inhibitor of AmpC. Ceftazidime cannot adopt a conformation competent for catalysis due to steric clashes that would occur with conserved residues Val211 and Tyr221. The X-ray crystal structure of the mutant beta-lactamase GC1, which has improved activity against third-generation cephalosporins, suggests that a tandem tripeptide insertion in the Omega loop, which contains Val211, has caused a shift of this residue and also of Tyr221 that would allow ceftazidime and other third-generation cephalosporins to adopt a more catalytically competent conformation. These structural differences may explain the extended spectrum activity of GC1 against this class of cephalosporins. In addition, the complexed structure of the transition-state analogue inhibitor (K(i) 20 nM) with AmpC reveals potential opportunities for further inhibitor design.

Acute and mid-term results of phosphorylcholine-coated stents in primary coronary stenting for acute myocardial infarction

The aim of this pilot study was to evaluate the safety and efficacy of the BiodivYsio phosphorylcholine-coated stent in the primary treatment of acute myocardial infarction. The BiodivYsio stent (Biocompatible) is a balloon-expandable stent, laser etched from a 316 L stainless steel tube. This device is coated with phosphorylcholine, a synthetic, hemocompatible phospholipid polymer that has been shown in experimental studies to reduce platelet and protein adhesion to the surface of the metal. One hundred consecutive patients within 24 hr of symptoms of onset of acute MI, treated with primary PTCA, were enrolled. After PTCA, stenting was attempted in all eligible lesions (reference diameter > or = 2.5 mm; no bend lesion > 45 degrees ). Poststenting regimens contained ticlopidine (500 mg/day) and aspirin (325 mg/day) and 6-12 hr of heparin infusion. Procedural success (TIMI > or = II and residual stenosis < 30%) was obtained in 70/74 cases (95%). TIMI grade III was restored in 90% of cases. In the patient group with procedural success (70 cases), 70 BiodivYsio stents were placed. After stenting, diameter stenosis decreased from 96% +/- 11% to 22% +/- 12% (P < 0.01) and minimal luminal diameter increased from 0.13 +/- 0.29 to 2.47 +/- 0.43 (P < 0.01). Nominal stent diameter was between 3.0 and 4.0 mm (mean, 3.5 +/- 0.4 mm). Stent length was between 11 and 28 mm (mean, 17 +/- 4.5 mm). Clinical follow-up was obtained in all patients; angiographic follow-up was performed in 65/70 (93%). No acute or subacute thrombosis was reported. Two in-hospital major adverse cardiac events (MACE) were reported due to a nontreated left main disease that required coronary artery bypass graft (CABG) surgery. At follow-up, MACE were found in 9 of 68 patients (13%), target lesion revascularization (TLR) in 6%, and CABG in the remaining 6%. Primary stenting with phosphorylcholine-coated stent leads to excellent short- and mid-term clinical outcomes and is associated with a restenosis rate of 12%.

Correlation between high frequency intravascular ultrasound and histomorphology in human coronary arteries

OBJECTIVE

To test the efficacy of high frequency intravascular ultrasound (IVUS) transducers in identifying lipid/necrotic pools in atherosclerotic plaques.

METHODS

40 MHz transducers were used for in vitro IVUS assessment of 12 arterial segments (10 coronary and two carotid arteries, dissected from five different necropsy cases). IVUS acquisition was performed at 0.5 mm/s after ligature of the branching points to generate a closed system. Lipid/necrotic areas were defined by IVUS as large echolucent intraplaque areas surrounded by tissue with higher echodensity. To obtain histopathological sections corresponding to IVUS cross sections, vessels were divided into consecutive 3 mm long segments using the most distal recorded IVUS image as the starting reference. Samples were then fixed with 10% buffered formalin, processed for histopathological study, serially cut, and stained using the Movat pentacrome method.

RESULTS

122 sections were analysed. Lipid pools were observed by histology in 30 sections (25%). IVUS revealed the presence of lipid pools in 19 of these sections (16%; sensitivity 65%, specificity 95%).

CONCLUSIONS

In vitro assessment of lipid/necrotic pools with high frequency transducers was achieved with good accuracy. This opens new perspectives for future IVUS characterisation of atherosclerotic plaques.

Correlation between high frequency intravascular ultrasound and histomorphology in human coronary arteries

OBJECTIVE

To test the efficacy of high frequency intravascular ultrasound (IVUS) transducers in identifying lipid/necrotic pools in atherosclerotic plaques.

METHODS

40 MHz transducers were used for in vitro IVUS assessment of 12 arterial segments (10 coronary and two carotid arteries, dissected from five different necropsy cases). IVUS acquisition was performed at 0.5 mm/s after ligature of the branching points to generate a closed system. Lipid/necrotic areas were defined by IVUS as large echolucent intraplaque areas surrounded by tissue with higher echodensity. To obtain histopathological sections corresponding to IVUS cross sections, vessels were divided into consecutive 3 mm long segments using the most distal recorded IVUS image as the starting reference. Samples were then fixed with 10% buffered formalin, processed for histopathological study, serially cut, and stained using the Movat pentacrome method.

RESULTS

122 sections were analysed. Lipid pools were observed by histology in 30 sections (25%). IVUS revealed the presence of lipid pools in 19 of these sections (16%; sensitivity 65%, specificity 95%).

CONCLUSIONS

In vitro assessment of lipid/necrotic pools with high frequency transducers was achieved with good accuracy. This opens new perspectives for future IVUS characterisation of atherosclerotic plaques.

Energetic, structural, and antimicrobial analyses of beta-lactam side chain recognition by beta-lactamases

BACKGROUND

Penicillins and cephalosporins are among the most widely used and successful antibiotics. The emergence of resistance to these beta-lactams, most often through bacterial expression of beta-lactamases, threatens public health. To understand how beta-lactamases recognize their substrates, it would be helpful to know their binding energies. Unfortunately, these have been difficult to measure because beta-lactams form covalent adducts with beta-lactamases. This has complicated functional analyses and inhibitor design.

RESULTS

To investigate the contribution to interaction energy of the key amide (R1) side chain of beta-lactam antibiotics, eight acylglycineboronic acids that bear the side chains of characteristic penicillins and cephalosporins, as well as four other analogs, were synthesized. These transition-state analogs form reversible adducts with serine beta-lactamases. Therefore, binding energies can be calculated directly from K(i) values. The K(i) values measured span four orders of magnitude against the Group I beta-lactamase AmpC and three orders of magnitude against the Group II beta-lactamase TEM-1. The acylglycineboronic acids have K(i) values as low as 20 nM against AmpC and as low as 390 nM against TEM-1. The inhibitors showed little activity against serine proteases, such as chymotrypsin. R1 side chains characteristic of beta-lactam inhibitors did not have better affinity for AmpC than did side chains characteristic of beta-lactam substrates. Two of the inhibitors reversed the resistance of pathogenic bacteria to beta-lactams in cell culture. Structures of two inhibitors in their complexes with AmpC were determined by X-ray crystallography to 1.90 A and 1.75 A resolution; these structures suggest interactions that are important to the affinity of the inhibitors.

CONCLUSIONS

Acylglycineboronic acids allow us to begin to dissect interaction energies between beta-lactam side chains and beta-lactamases. Surprisingly, there is little correlation between the affinity contributed by R1 side chains and their occurrence in beta-lactam inhibitors or beta-lactam substrates of serine beta-lactamases. Nevertheless, presented in acylglycineboronic acids, these side chains can lead to inhibitors with high affinities and specificities. The structures of their complexes with AmpC give a molecular context to their affinities and may guide the design of anti-resistance compounds in this series.

Intracoronary ultrasound measurements in women with myocardial infarction without significant coronary lesions

METHODS

Morphologic characteristics of coronary arteries in eight women with myocardial infarction and angiographically normal or not significantly stenosed vessels were investigated with intracoronary ultrasound. The infarct-related vessel was assessed by three-dimensional volumetric analysis and compared with a control vessel from a noninfarcted area.

RESULTS

Atherosclerosis was found in all infarct-related arteries. The plaques were predominantly soft, eccentric, poorly calcified, and with little lipid pools or none at all. Although the average area and thickness of plaques and cross-sectional narrowing of the infarct-related arteries were greater than those of control arteries, there were no pathognomonic characteristics of plaques in the infarct-related vessels.

CONCLUSION

The possibility that atherosclerosis is the main etiologic factor for myocardial infarction can not be excluded even for women without an angiographically obvious coronary stenosis in the infarct-related vessels.

Intravascular ultrasound insights into plaque composition

Previous studies correlating histomorphology with 20-30 MHz-derived intravascular ultrasound (IVUS) images showed that IVUS provides to some extent qualitative information on plaque composition. IVUS imaging proved to define calcifications with high sensitivity and specificity but was found to be less accurate in the assessment of soft components. Nevertheless previous studies on atherosclerotic plaque characterization were limited by use of low-frequency transducers that did not define accurately soft components. Our goal was to test the effectiveness of high frequency IVUS transducers in the identification of lipid/necrotic pools in atherosclerotic plaques.

METHODS

Forty MHz transducers were used for in vitro IVUS assessment of 12 arterial segments (10 coronary arteries and 2 carotid arteries dissected from 5 different autopsy cases). IVUS acquisition was performed at a 0.5 mm/s speed after ligature of the branching points to generate a closed system. Lipid necrotic areas were defined by IVUS as large echolucent intraplaque areas surrounded by tissue with higher echodensity. To obtain histopathologic sections corresponding to IVUS cross sections, vessels were divided into consecutive 3 mm-long segments using the most distal recorded IVUS image as the starting reference. Then, samples were fixed with 10% buffered formalin, processed for histopathologic study, serially cut, and stained with the Movat penthacrome method.

RESULTS

One hundred twenty-two sections were analyzed. Lipid pools were observed by histology in 30 cross sections (25%). IVUS revealed the presence of lipid pools in 19 of 122 cross sections with a sensitivity and specificity of 67% and 94%, respectively.

CONCLUSIONS

High frequency transducers accurately identify lipid/necrotic pools and open new perspectives on future IVUS characterization of atherosclerotic plaques.

Screening of health care workers for hepatitis B virus and hepatitis C virus: criteria for fitness for work

The aim of this study was to propose a protocol for assessment of markers of infection with hepatitis B virus (HBV) and hepatitis C virus (HCV) in exposed health care professionals and to define criteria for evaluation of fitness for the job of the infected personnel. The study comprised 800 persons involved in operative procedures, including 414 surgeons, 275 nurses, and 111 anaesthetists. A graduated protocol was created for monitoring markers of HBV and HCV infection. A well-defined combination of markers of antigen-antibody systems enabled identification of four groups of persons with HBV infection differing in fitness for work: 1) HBsAg-positive, HBeAg-positive, HBV DNA-positive; 2) HBsAg-positive, anti-HBe-positive, HBV DNA-positive; 3) HBsAg-positive, anti-HBe-positive, HBV DNA-negative; and 4) anti-HBs-positive, anti-HBc-positive, anti-HBe-positive group. For HCV infection, two groups with different job fitness were identified: 1) anti-HCV-positive, HCV RNA-negative and 2) anti-HCV-positive, HCV RNA-positive. Screening of hospital personnel at risk to HBV and HCV infection requires a well-defined protocol which may help to evaluate the fitness of the infected personnel for a specific job.

[Use of diverse diagnostic techniques in the study of silicosis]

This study would examine the efficiency of different diagnostic tools, imaging and functional, in the study of pulmonary system of workers exposed to silicotigen dusts. 24 male miners were examined with chest H.R.T.C., spirometry with study of DLCO and of total lung capacity. 13 of 24 miners were submitted to pulmonary ventilatory scintigraphy (99mTcDTPA). All 24 miners were previously yet submitted to two follow-up by means of chest radiography in conformity with ILO guidelines. The chest radiography, even evaluated in conformity with ILO guidelines, is subject to remarkable differences when performed and reported by different operator. Useful data are provided by functional studies. H.R.T.C. is necessary to evaluate the degree of parenchymal involvement and for medicolegal porpoises. Scintigraphy with 99mTc DTPA need of further studies in the evaluation of exposure to silicotigen dusts.

From plaque biology to clinical setting

Coronary atherosclerosis may cause acute and chronic ischemic syndromes; the former are caused by "acute plaque events," mostly thrombosis complicating vulnerable ruptured plaques, namely severe lesions with large core, thin cap, and weak shoulder infiltrated by activated inflammatory cells. Plaque rupture may also occur in nonischemic settings and is not obligatorily complicated by thrombosis. Furthermore, plaque rupture is not the only thrombus substrate in acute ischemic syndromes: Superficial erosion of fibrous plaques is found in 44% of acute thrombi in sudden coronary deaths and in 25% of those in acute myocardial infarctions. Coronary thrombosis appears to be triggered by superficial intimal inflammation in plaque ulceration and by neointimal hyperplasia in plaque erosion. "Endogenous" and, recently, exogenous factors, particularly infective intracellular organisms, have been proposed as major contributors to plaque inflammation, activation, and vulnerability. Possible exogenous triggers are DNA and RNA viruses and intracellular bacteria such as Chlamydia pneumoniae, which has been identified with microbiological, ultrastructural, immunohistochemical, and molecular tools in a consistent proportion of human plaque samples. Chlamydia increases local thrombogenicity and is associated with an atherogenic lipid profile. Systemic indexes of inflammation, such as PCR, SAA, and fibrinogen, are also increased in acute syndromes and common infectious diseases with high morbidity and minimal clinical impact are good candidates; Helicobacter pylori is a major one. Infectious agents could link local and systemic inflammation: White cells infected in its target tissue could circulate into the flow and be captured, on a specific local trigger, into vessel walls thus stimulating local inflammation.