The neutrophil to lymphocyte ratio associates with markers of Alzheimer's disease pathology in cognitively unimpaired elderly people

Background

An elevated neutrophil-lymphocyte ratio (NLR) in blood has been associated with Alzheimer's disease (AD). However, an elevated NLR has also been implicated in many other conditions that are risk factors for AD, prompting investigation into whether the NLR is directly linked with AD pathology or a result of underlying comorbidities. Herein, we explored the relationship between the NLR and AD biomarkers in the cerebrospinal fluid (CSF) of cognitively unimpaired (CU) subjects. Adjusting for sociodemographics, APOE4, and common comorbidities, we investigated these associations in two cohorts: the Alzheimer's Disease Neuroimaging Initiative (ADNI) and the M.J. de Leon CSF repository at NYU. Specifically, we examined associations between the NLR and cross-sectional measures of amyloid-β42 (Aβ42), total tau (t-tau), and phosphorylated tau181 (p-tau), as well as the trajectories of these CSF measures obtained longitudinally.

Results

A total of 111 ADNI and 190 NYU participants classified as CU with available NLR, CSF, and covariate data were included. Compared to NYU, ADNI participants were older (73.79 vs. 61.53, p < 0.001), had a higher proportion of males (49.5% vs. 36.8%, p = 0.042), higher BMIs (27.94 vs. 25.79, p < 0.001), higher prevalence of hypertensive history (47.7% vs. 16.3%, p < 0.001), and a greater percentage of Aβ-positivity (34.2% vs. 20.0%, p = 0.009). In the ADNI cohort, we found cross-sectional associations between the NLR and CSF Aβ42 (β=-12.193, p = 0.021), but not t-tau or p-tau. In the NYU cohort, we found cross-sectional associations between the NLR and CSF t-tau (β = 26.812, p = 0.019) and p-tau (β = 3.441, p = 0.015), but not Aβ42. In the NYU cohort alone, subjects classified as Aβ+ (n = 38) displayed a stronger association between the NLR and t-tau (β = 100.476, p = 0.037) compared to Aβ- subjects or the non-stratified cohort. In both cohorts, the same associations observed in the cross-sectional analyses were observed after incorporating longitudinal CSF data.

Conclusions

We report associations between the NLR and Aβ42 in the older ADNI cohort, and between the NLR and t-tau and p-tau181 in the younger NYU cohort. Associations persisted after adjusting for comorbidities, suggesting a direct link between the NLR and AD. However, changes in associations between the NLR and specific AD biomarkers may occur as part of immunosenescence.

Association of biological sex with clinical outcomes and biomarkers of Alzheimer's disease in adults with Down syndrome

The study of sex differences in Alzheimer's disease is increasingly recognized as a key priority in research and clinical development. People with Down syndrome represent the largest population with a genetic link to Alzheimer's disease (>90% in the 7th decade). Yet, sex differences in Alzheimer's disease manifestations have not been fully investigated in these individuals, who are key candidates for preventive clinical trials. In this double-centre, cross-sectional study of 628 adults with Down syndrome [46% female, 44.4 (34.6; 50.7) years], we compared Alzheimer's disease prevalence, as well as cognitive outcomes and AT(N) biomarkers across age and sex. Participants were recruited from a population-based health plan in Barcelona, Spain, and from a convenience sample recruited via services for people with intellectual disabilities in England and Scotland. They underwent assessment with the Cambridge Cognitive Examination for Older Adults with Down Syndrome, modified cued recall test and determinations of brain amyloidosis (CSF amyloid-β 42 / 40 and amyloid-PET), tau pathology (CSF and plasma phosphorylated-tau181) and neurodegeneration biomarkers (CSF and plasma neurofilament light, total-tau, fluorodeoxyglucose-PET and MRI). We used within-group locally estimated scatterplot smoothing models to compare the trajectory of biomarker changes with age in females versus males, as well as by apolipoprotein ɛ4 carriership. Our work revealed similar prevalence, age at diagnosis and Cambridge Cognitive Examination for Older Adults with Down Syndrome scores by sex, but males showed lower modified cued recall test scores from age 45 compared with females. AT(N) biomarkers were comparable in males and females. When considering apolipoprotein ɛ4, female ɛ4 carriers showed a 3-year earlier age at diagnosis compared with female non-carriers (50.5 versus 53.2 years, P = 0.01). This difference was not seen in males (52.2 versus 52.5 years, P = 0.76). Our exploratory analyses considering sex, apolipoprotein ɛ4 and biomarkers showed that female ɛ4 carriers tended to exhibit lower CSF amyloid-β 42/amyloid-β 40 ratios and lower hippocampal volume compared with females without this allele, in line with the clinical difference. This work showed that biological sex did not influence clinical and biomarker profiles of Alzheimer's disease in adults with Down syndrome. Consideration of apolipoprotein ɛ4 haplotype, particularly in females, may be important for clinical research and clinical trials that consider this population. Accounting for, reporting and publishing sex-stratified data, even when no sex differences are found, is central to helping advance precision medicine.

Hippocampal Subfield Volumes Predict Disengagement from Maintenance Treatment in First Episode Schizophrenia

OBJECTIVES

Disengagement from treatment is common in first episode schizophrenia (FES) and is associated with poor outcomes. Our aim was to determine whether hippocampal subfield volumes predict disengagement during maintenance treatment of FES.

METHODS

FES patients were recruited from sites in Boston, New York, Shanghai, and Changsha. After stabilization on antipsychotic medication, participants were randomized to add-on citalopram or placebo and followed for 12 months. Demographic, clinical and cognitive factors at baseline were compared between completers and disengagers in addition to volumes of hippocampal subfields.

RESULTS

Baseline data were available for 95 randomized participants. Disengagers (n = 38, 40%) differed from completers (n = 57, 60%) by race (more likely Black; less likely Asian) and in more alcohol use, parkinsonism, negative symptoms and more impairment in visual learning and working memory. Bilateral dentate gyrus (DG), CA1, CA2/3 and whole hippocampal volumes were significantly smaller in disengagers compared to completers. When all the eight volumes were entered into the model simultaneously, only left DG volume significantly predicted disengagement status and remained significant after adjusting for age, sex, race, intracranial volume, antipsychotic dose, duration of untreated psychosis, citalopram status, alcohol status, and smoking status (P < .01). Left DG volume predicted disengagement with 57% sensitivity and 83% specificity.

CONCLUSIONS

Smaller left DG was significantly associated with disengagement status over 12 months of maintenance treatment in patients with FES participating in a randomized clinical trial. If replicated, these findings may provide a biomarker to identify patients at risk for disengagement and a potential target for interventions.

Data-Driven Clustering of Functional Signals Reveals Gradients in Processing Both within the Anterior Hippocampus and across Its Long Axis

A particularly elusive puzzle concerning the hippocampus is how the structural differences along its long anteroposterior axis might beget meaningful functional differences, particularly in terms of the granularity of information processing. One measure posits to quantify this granularity by calculating the average statistical independence of the BOLD signal across neighboring voxels, or intervoxel similarity (IVS), and has shown the anterior hippocampus to process coarser-grained information than the posterior hippocampus. This measure, however, has yielded opposing results in studies of developmental and healthy aging samples, which also varied in fMRI acquisition parameters and hippocampal parcellation methods. To reconcile these findings, we measured IVS across two separate resting-state fMRI acquisitions and compared the results across many of the most widely used parcellation methods in a large young-adult sample of male and female humans (Acquisition 1, N = 233; Acquisition 2, N = 176). Finding conflicting results across acquisitions and parcellations, we reasoned that a data-driven approach to hippocampal parcellation is necessary. To this end, we implemented a group masked independent components analysis to identify functional subunits of the hippocampus, most notably separating the anterior hippocampus into separate anterior-medial, anterior-lateral, and posteroanterior-lateral components. Measuring IVS across these components revealed a decrease in IVS along the medial-lateral axis of the anterior hippocampus but an increase from anterior to posterior. We conclude that intervoxel similarity is deeply affected by parcellation and that grounding one's parcellation in a functionally informed approach might allow for a more complex and reliable characterization of the hippocampus.SIGNIFICANCE STATEMENT Processing information along hierarchical scales of granularity is critical for many of the feats of cognition considered most human. Recently, the changes in structure, cortical connectivity, and apparent functional properties across parcels of the hippocampal long axis have been hypothesized to underlie this hierarchical gradient in information processing. We show here, however, that the choice of parcellation method itself drastically affects one particular measure of granularity across the hippocampus and that a functionally informed approach to parcellation reveals gradients both within the anterior hippocampus and in nonlinear form across the long axis. These results point to the issue of parcellation as a critical one in the study of the hippocampus and reorient interpretation of existing results.

CRF serum levels differentiate PTSD from healthy controls and TBI in military veterans

Background and Objective

Posttraumatic stress disorder (PTSD) is a serious and frequently debilitating psychiatric condition that can occur in people who have experienced traumatic stressors, such as war, violence, sexual assault and other life‐threatening events. Treatment of PTSD and traumatic brain injury (TBI) in veterans is challenged by diagnostic complexity, partially due to PTSD and TBI symptoms overlap and to the fact that subjective self‐report assessments may be influenced by a patient's willingness to share their traumatic experiences and resulting symptoms. Corticotropin‐releasing factor (CRF) is one of the main mediators of hypothalamic pituitary adrenal (HPA)‐axis responses in stress and anxiety.

Methods and Results

We analyzed serum CRF levels in 230 participants including heathy controls (64), and individuals with PTSD (53), TBI (70) or PTSD + TBI (43) by enzyme immunoassay (EIA). Significantly lower CRF levels were found in both the PTSD and PTSD + TBI groups compared to healthy control (PTSD vs. Controls: P = 0.0014, PTSD + TBI vs. Controls: P = 0.0011) and chronic TBI participants (PTSD vs. TBI: P < 0.0001, PTSD + TBI vs. TBI: P < 0.0001), suggesting a PTSD‐related mechanism independent from TBI and associated with CRF reduction. CRF levels negatively correlated with PTSD severity on the Clinically Administered PTSD Scale (CAPS‐5) scale in the whole study group.

Conclusions

Hyperactivation of the HPA axis has been classically identified in acute stress. However, the recognized enhanced feedback inhibition of the HPA axis in chronic stress supports our findings of lower CRF in PTSD patients. This study suggests that reduced serum CRF in PTSD should be further investigated. Future validation studies will establish if CRF is a possible blood biomarker for PTSD and/or for differentiating PTSD and chronic TBI symptomatology.

The HPA axis is activated under acute stress conditions, but an enhanced feedback inhibition may be prevalent in chronic stress conditions such as PTSD.

We observed a reduction in serum CRF levels in veterans with PTSD and PTSD + TBI, but not in veterans with chronic TBI alone.

A serum CRF reduction may be indicative of CNS mechanisms specific to PTSD and should be further evaluated as a possible peripheral biomarker.

Effect of citalopram on hippocampal volume in first-episode schizophrenia: Structural MRI results from the DECIFER trial

Hippocampal volume loss is prominent in first episode schizophrenia (FES) and has been associated with poor clinical outcomes and with BDNF genotype; antidepressants are believed to reverse hippocampal volume loss via release of BDNF. In a 12-month, placebo-controlled add-on trial of the antidepressant, citalopram, during the maintenance phase of FES, negative symptoms were improved with citalopram. We now report results of structural brain imaging at baseline and 6 months in 63 FES patients (34 in citalopram group) from the trial to assess whether protection against hippocampal volume loss contributed to improved negative symptoms with citalopram. Hippocampal volumetric integrity (HVI) did not change significantly in the citalopram or placebo group and did not differ between treatment groups, whereas citalopram was associated with greater volume loss of the right CA1 subfield. Change in cortical thickness was associated with SANS change in 4 regions (left rostral anterior cingulate, right frontal pole, right cuneus, and right transverse temporal) but none differed between treatment groups. Our findings suggest that minimal hippocampal volume loss occurs after stabilization on antipsychotic treatment and that citalopram's potential benefit for negative symptoms is unlikely to result from protection against hippocampal volume loss or cortical thinning.

Clinical Trials for Opioid Use Disorder

This chapter describes recent clinical trials for opioid use disorder (OUD), an area that has rapidly accelerated in response to the opioid overdose crisis in the USA and newly appropriated funding. Trials involve a wide range of compounds including cannabinoids and psychedelics, new and existing compounds targeting domains emerging from addiction neuroscience, agents repurposed from other indications, and novel strategies including vaccines, enzymes, and other biologicals. In parallel, new formulations of existing compounds offer immediate promise, as do a variety of web-based interventions and smartphone-delivered apps. Trials focused on implementing existing effective interventions in mainstream healthcare settings, and others focused on special populations, e.g., adolescents, criminal justice, pregnant women, native Americans, etc., have the potential to vastly expand treatment in the near term. Given the range of ongoing and recent trials, this chapter is not intended to be an exhaustive review but rather to present an overview of approaches within the framework of the opioid treatment cascade and the context of current OUD pharmacotherapies.

Sexual Dimorphism and Hemispheric Asymmetry of Hippocampal Volumetric Integrity in Normal Aging and Alzheimer Disease

BACKGROUND AND PURPOSE

Asymmetric atrophy of the hippocampus is an important clinical finding in normal aging and Alzheimer disease. In this study, we investigate the associations between the magnitude and asymmetry of hippocampal volumetric integrity and age, sex, and dementia severity.

MATERIALS AND METHODS

We have recently developed a rapid fully automatic algorithm to measure the hippocampal parenchymal fraction, an index of hippocampal volumetric integrity on structural MR imaging of the brain. We applied this algorithm to measure the hippocampal parenchymal fraction bilaterally on 775 MR imaging volumes scanned from 198 volunteers in a publicly available data base. All subjects were right-handed and older than 60 years of age. Subjects were categorized as cognitively healthy (n = 98), with mild cognitive impairment (n = 70), or with mild/moderate Alzheimer disease (n = 30). We used linear mixed-effects models to analyze the hippocampal parenchymal fraction and its asymmetry with respect to age, sex, dementia severity, and intracranial volume.

RESULTS

After controlling for age, sex, and intracranial volume, we found that the magnitude of the hippocampal parenchymal fraction decreased and its asymmetry increased significantly with dementia severity. Also, hippocampal parenchymal fraction asymmetry was significantly higher in men after controlling for all other variables, but there was no sex effect on hippocampal parenchymal fraction magnitude. The magnitude of the hippocampal parenchymal fraction decreased and its asymmetry increased significantly with age in subjects who were cognitively healthy, but associations with age were different in nature in the mild cognitive impairment and Alzheimer disease groups.

CONCLUSIONS

Hippocampal atrophy progresses asymmetrically with age in cognitively healthy subjects. Hippocampal parenchymal fraction asymmetry is significantly higher in men than women and in mild cognitive impairment/Alzheimer disease relative to cognitively healthy individuals.

The effectiveness of the paclitaxel-coated Luminor® balloon catheter versus an uncoated balloon catheter in superficial femoral and popliteal arteries in preventing vessel restenosis or reocclusion: study protocol for a randomized controlled trial

BACKGROUND

The aim of this investigator-initiated trial is to evaluate the safety and efficacy of the novel Luminor® paclitaxel-coated drug-eluting balloon (DEB) catheter (iVascular, S.L.U., Barcelona, Spain) in inhibiting restenosis and in ensuring long-term vascular patency.

METHODS/DESIGN

This is a multicenter randomized controlled trial to evaluate the Luminor® paclitaxel-coated DEB catheter for stenotic or occlusive lesions (length ≤15 cm) in the superficial femoral artery (SFA) and the popliteal artery (PA) up to the P1 segment compared to the noncoated, plain old balloon angioplasty (POBA) catheter. In total 172 subjects will be treated with either the DEB catheter or the POBA catheter in 11 German study centers in a 1:1 randomization study design. The primary endpoint is late lumen loss (LLL) at 6 months. Secondary endpoints are patency rate, target lesion/vessel revascularization, quality of life (assessed with the Walking Impairment Questionnaire (WIQ) and the EQ-5D), change of Rutherford stage and ankle-brachial index, major and minor amputation rate at the index limb, number of dropouts and all-cause mortality.

DISCUSSION

EffPac represents a randomized controlled trial that will provide evidence on the effectiveness of the Luminor® paclitaxel-coated DEB catheter for the reduction of restenosis compared to the POBA catheter for the SFA and the PA. The results of EffPac will allow direct comparison to other already-completed RCTs applying paclitaxel-coated DEBs from different manufacturers with different coating technologies in the same target vessel.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02540018 , registered on 17 August 2015. Protocol version: CIP Version Final04, 11 February 2016. EUDAMED No: CIV-15-03-013204.

Offroad re-entry catheter system for subintimal recanalization of chronic total occlusions in femoropopliteal arteries: primary safety and effectiveness results of the re-route trial

AIM

Aim of the study was to provide additional clinical data regarding the safety and technical success of the OffRoad Re-Entry Catheter System (Boston Scientific, Natick, MA, USA) for subintimal recanalization of chronic total occlusions (CTO) in the femoropopliteal arteries.

METHODS

A total of 92 patients (mean age 70.3±10.6 years; 70% male) were enrolled in this prospective, single-arm, post-market study conducted at 12 European centers. Patients were required to have claudication or critical limb ischemia and a CTO lesion in a native femoropopliteal artery. The primary safety endpoint was the composite rate of device-related major adverse events (MAEs; i.e., death, perforation requiring intervention, clinically significant peripheral embolism, and major amputation of the treated lower limb) at 30 days. Effectiveness was based on device technical success, defined as placement of a guidewire in the true lumen distal to a CTO.

RESULTS

Ninety patients were evaluable for the primary safety endpoint. The 30-day device-related MAE rate was 3.3% (3/90), with an upper confidence bound of 6.5%, which was lower than the prespecified performance goal of 15%. All 3 events were clinically significant peripheral emboli. Technical success was 84.8% (78/92) with a lower confidence bound of 78.6%, which exceeded the prespecified performance goal of 76%. A decrease of ≥1 Rutherford category was observed in 75% (65/87) of patients at the 30 day visit.

CONCLUSION

The Re-ROUTE trial results demonstrate acceptable performance of the OffRoad system in terms of safety and technical success for the recanalization of femoropopliteal CTOs.

Atypical antipsychotics cause an acute increase in cutaneous hand blood flow in patients with schizophrenia and schizoaffective disorder

OBJECTIVE

Clinical studies suggest resting thermoregulatory cutaneous vasomotor tone could be increased in schizophrenia, resulting in reduced hand blood flow. In animal models, atypical antipsychotics including clozapine potently inhibit sympathetic neural outflow to the thermoregulatory cutaneous vascular beds. We have now determined whether antipsychotic medication administration is associated with an acute increase in hand blood flow in patients with schizophrenia and schizoaffective disorder, and whether this increase correlates with clinical status.

METHOD

Hand temperature was measured with an infrared camera in 12 patients with chronic schizophrenia or schizoaffective disorder 30 min prior to, then 30 and 60 min following medication. Clinical status was assessed via the Brief Psychiatric Rating Scale (BPRS). Results were compared using regression and repeated measures analysis of variance.

RESULTS

A robust and significant increase in hand temperature (p < 0.001) was observed following antipsychotic administration. The mean increase after 60 min was 4.1 ± 2.4°C. This increase was significantly associated with colder hand temperature prior to medication (p < 0.05; suggestive of increased resting vasoconstriction) and with more severe psychiatric symptoms (p < 0.05).

CONCLUSIONS

Atypical antipsychotics were associated with increased hand blood flow, consistent with inhibition of thermoregulatory sympathetic outflow to the cutaneous vascular bed in patients with schizophrenia and schizoaffective disorder. This increase correlated with symptom severity. Hand temperature increase following antipsychotic medication may therefore be a simple and informative physiological marker of disease activity and potential response in patients with schizophreniform disorders. Given that antipsychotics also inhibit sympathetic outflow to brown adipose tissue, which normally converts energy to heat, future studies should examine whether antipsychotic-induced hand temperature increase is associated with antipsychotic-induced weight gain.

Rosuvastatin reduces neointima formation in a rat model of balloon injury

BACKGROUND

Processes of restenosis, following arterial injury, are complex involving different cell types producing various cytokines and enzymes. Among those enzymes, smooth muscle cell-derived matrix metalloproteinases (MMPs) are thought to take part in cell migration, degrading of extracellular matrix, and neointima formation. MMP-9, also known as gelatinase B, is expressed immediately after vascular injury and its expression and activity can be inhibited by statins. Using an established in vivo model of vascular injury, we investigated the effect of the HMG-CoA reductase inhibitor rosuvastatin on MMP-9 expression and neointima formation.

MATERIALS AND METHODS

14-week old male Sprague Dawley rats underwent balloon injury of the common carotid artery. Half of the animals received rosuvastatin (20 mg/kg body weight/day) via oral gavage, beginning 3 days prior to injury. Gelatinase activity and neointima formation were analyzed 3 days and 14 days after balloon injury, respectively. 14 days after vascular injury, proliferative activity was assessed by staining for Ki67.

RESULTS

After 14 days, animals in the rosuvastatin group showed a decrease in total neointima formation (0.194±0.01 mm2 versus 0.124±0.02 mm2, p<0.05) as well as a reduced intima/media ratio (1.26±0.1 versus 0.75±0.09, p<0.05). Balloon injury resulted in increased activity of MMP-9 3 days after intervention for both rosuvastatin treated animals and controls with no significant difference observed between the groups. There was a trend towards a reduction in the number of Ki67-positive cells 14 days after injury.

CONCLUSIONS

Rosuvastatin attenuates neointima formation without affecting early MMP-9 activity in a rat model of vascular injury.

Radial artery thrombosis following transradial coronary angiography: incidence and rationale for treatment of symptomatic patients with low-molecular-weight heparins

BACKGROUND

Transradial access for diagnostic and therapeutic coronary angiography gains more and more popularity because of its advantages over the femoral approach, enhancing patient comfort, reducing bleeding complications and duration of hospital stay. However, these benefits are overshadowed by an increased rate of radial artery (RA) occlusion. There are little data regarding the exact incidence, potential predictors and outcome of post-procedural RA occlusions. Furthermore, there is no clear evidence for the optimal treatment of this complication.

METHODS

In a single-centre prospective observational study, 488 consecutive patients were evaluated by ultrasound the day after transradial cardiac catheterization for signs of RA occlusion. Symptomatic patients with sonographically identified radial artery thrombosis underwent treatment with low-molecular-weight heparin (LMWH) for 4 weeks. Asymptomatic patients did not receive anticoagulation therapy. The primary endpoint was the patency rate of the radial artery at 4 weeks of follow-up.

RESULTS

Radial artery thrombosis was found in 51 of 488 (10.5%) patients 1 day after transradial cardiac catheterization. 30 (58.8%) patients showed symptoms on access site, whereas 21 (41.2%) did not show any symptoms. After 4 weeks, 26 (86.7%) of the symptomatic patients showed a partial or complete recanalization of the radial artery after treatment with LMWH, compared with 4 (19.1%) of the asymptomatic patients without anticoagulation (P < 0.001).

CONCLUSION

Radial artery thrombosis is a frequent complication after transradial coronary angiography. Incidence of RA occlusion is underestimated due to the often asymptomatic clinical course. Treatment of symptomatic RA occlusion with low-molecular-weight heparins significantly increases patency rates after 4 weeks.

A 6 week course of azithromycin treatment has no beneficial effect on atherosclerotic lesion development in apolipoprotein E-deficient mice chronically infected with Chlamydia pneumoniae

OBJECTIVES

To evaluate whether antimicrobial chemotherapy prevents acceleration of atherosclerotic lesion development induced by infection with Chlamydia pneumoniae.

METHODS

ApoE-deficient mice which develop hyperlipidaemia and atherosclerosis spontaneously were inoculated intranasally with C. pneumoniae. Animals were treated with azithromycin for 6 weeks after the third inoculation and the atherosclerotic lesion areas in the aortic sinus were measured by computer-assisted morphometry.

RESULTS

At 12 weeks post-infection, infected untreated animals developed significantly larger lesion areas compared with sham-inoculated controls (8.7 x 10(4)+/-2.3 x 10(4) microm(2) versus 5.6 x 10(4)+/-2.4 x 10(4) microm(2)). However, there were no differences in lesion size of infected mice treated with azithromycin in comparison with untreated infected controls (11.0 x 10(4)+/-3.0 x 10(4) microm(2) versus 8.7 x 10(4)+/-2.3 x 10(4) microm(2)).

CONCLUSIONS

Antibiotic treatment against C. pneumoniae has no beneficial effects on hyperlipidaemia-induced atherosclerosis accelerated by C. pneumoniae in a mouse model.

Fibrinogen induces chemotactic activity in endothelial cells

Chemotaxis of blood monocytes into the vessel wall together with the change of the relative content of the extracellular matrix (ECM) proteins at sites of predilection is an early cellular marker of atherogenesis. To examine the influence of ECM proteins on secretion of chemoattractants by endothelial cells (EC), porcine EC were seeded on gelatin (G), fibronectin (Fn) and fibrinogen (Fg). After 24 h cells seeded on G and Fn showed the histiotypic 'cobblestone'-morphology whereas cells seeded on Fg did not. Chemotactic activity for monocytes in supernatants from cells seeded on Fg was more than two-fold higher compared with G and was independent of soluble Fn or Fg in the supernatant. Quantification of monocyte chemoattracting protein-1, PDGF-AB and IL-8 in EC supernatants showed that Fg led to a significant increase in secretion of all three proteins compared with cells cultured on G. Preincubation of porcine EC with the tripeptide arginine-glycine-aspartic acid, as inhibitor of binding of Fg to integrin receptors, but not with the control tripeptide arginine-glycine-glutamic acid showed a decrease in chemotactic activity for cells cultured on Fg but not on Fn or G. Inhibition of protein kinase C (PKC) activity in EC by GF109203 resulted in a decrease of fibrinogen-induced chemotactic activity. Also the tyrosine-kinase inhibitor herbimycin inhibited fibrinogen mediated secretion of chemokines. The role of the PKC pathway for matrix mediated signal transduction is further corroborated by Fg-dependent induction of the PKC isoform delta. These data indicate an integrin-dependent signal transduction pathway leading to induction of chemotactic activity by the ECM protein fibrinogen. This mechanism may contribute to induction of chemokines in early atherosclerotic lesions.

Chlamydia pneumoniae infection accelerates hyperlipidemia induced atherosclerotic lesion development in C57BL/6J mice

Considerable evidence of an association between Chlamydia pneumoniae infections and cardiovascular disease has emerged. Animal models using genetically altered mice and hypercholesterolemic rabbits have shown a pathogenic role of C. pneumoniae in accelerating atherosclerotic plaque development. In the present study, we evaluated the effect of chronic C. pneumoniae infection on atherosclerosis in C57BL/6J mice, fed either a regular chow diet or a high fat, high cholesterol diet. Infected animals on an atherogenic diet developed significantly larger lesion areas compared with control mice at 18 weeks (2.5-fold increase; 4177+/-777 vs. 1650+/-808 microm(2); P<0.05) and 24 weeks of age (3.3-fold increase; 14139+/-4147 vs. 4298+/-869 microm(2); P<0.02). This study shows that chronic C. pneumoniae infection accelerates atherosclerotic lesion development in diet induced hypercholesterolemic mice, indicating that C. pneumoniae is a co-risk factor of hyperlipidemia in atherogenesis.

Phosphorylation of cytokeratin 8 and 18 in human vascular smooth muscle cells of atherosclerotic lesions and umbilical cord vessels

Expression of cytokeratins (CK) is considered a hallmark of the state of epithelial differentiation. CK also occur in certain vascular smooth muscle cells (VSMC), inferring an association with a less differentiated phenotype. Recently, CK posttranslational modification was shown to occur in epithelial cells in stress, mitosis or apoptosis. The aim of this study was to determine potential CK phosphorylation patterns in human VSMC. Tissue samples of normal peripheral and coronary arteries, atherosclerotic lesions and umbilical cord vessels were evaluated by immunofluorescence microscopy applying antibodies specific for cytokeratins 8 and 18, specific cytokeratin phosphorylation sites, Ki-67-antigen as a proliferation marker and nick end labeling (TUNEL) to detect apoptosis. All samples contained cytokeratin-positive VSMC but diverse phosphorylation patterns. The C-terminal serine 431 of cytokeratin 8 (CK8Ser-431) was phosphorylated in the vast majority of CK-expressing VSMC of coronary artery lesions. Only a subset of these cells demonstrated phosphorylation of CK18Ser-33 or, to an even lesser extent, CK8Ser-73. DNA fragmentation occurred predominantly in samples containing cells with phosphorylated CK8Ser-431 domains. In contrast, occluded peripheral lesions exhibited little or no phosphorylation. Neonatal VSMC in umbilical cord vessels contain abundant phosphorylated CK domains, again predominantly CK8Ser-431, but also CK18Ser-33. Again, only single cells were found to be proliferating or to contain DNA fragmentation. Thus, abundant CK phosphorylation in VSMC of atherosclerotic lesions suggests a specific functional response to cell stress and a possible relation to apoptosis.

Effect of Chlamydia trachomatis infection on atherosclerosis in apolipoprotein E-deficient mice

We have previously demonstrated that Chlamydia pneumoniae accelerates plaque formation in apolipoprotein E-deficient (ApoE(-/-)) mice following intranasal inoculations. In this study, we evaluated the effect of respiratory tract infection with Chlamydia trachomatis on the progression of atherosclerosis in ApoE(-/-) mice. The study showed that in contrast to infection with Chlamydia pneumoniae, infection of the lung and aorta with C. trachomatis was mild and transient and did not significantly accelerate plaque development.

Chlamydia pneumoniae induces inflammatory changes in the heart and aorta of normocholesterolemic C57BL/6J mice

Chlamydia pneumoniae infection induces inflammatory changes in blood vessels in normocholesterolemic rabbits, but it is not known whether the same phenomenon occurs in other animal models. Thus, in this study, C57BL/6J mice were inoculated with C. pneumoniae. Inflammatory changes in the heart or aorta were observed in a small number of chronically infected mice. No evidence of atherosclerotic lesions was found in any of the mice. These findings suggest that chronic C. pneumoniae infection can induce inflammatory changes in the heart and aorta of C57BL/6J mice, but does not initiate definitive atherosclerosis.

Chlamydia, inflammation, and atherogenesis

Atherosclerotic lesions are initiated and progress largely as a result of a chronic, fibroproliferative, inflammatory response. This review discusses how Chlamydia pneumoniae could conceivably contribute to this chronic inflammatory response and reports on recent in vivo and in vitro studies. In vivo studies in mice demonstrate that C. pneumoniae infection is disseminated to the artery wall following infection in the lung by alveolar macrophages. Recent in vitro studies show that infected U937 cells can directly transfer infection to endothelial cells and can indirectly increase the susceptibility of endothelial cells to C. pneumoniae infection. Loading of RAW 264.7 cells with modified forms of low-density lipoprotein increases the resistance of the cells to C. pneumoniae infection and also increases the susceptibility to the combined toxic effects of modified lipids and C. pneumoniae infection.

Mouse models of C. pneumoniae infection and atherosclerosis

Mouse models were used to determine whether Chlamydia pneumoniae establishes chronic infection of the aorta and contributes to atherogenesis. Persistent infection of the aorta occurred in 11 of 31 hyperlipidemic apolipoprotein E-deficient (apoE(-/-)) mice but not in C57BL/6J mice fed a normal diet after a single inoculation and in both models following repeated inoculation with C. pneumoniae. Repeated inoculation of C57BL/6J mice resulted in inflammatory changes in the heart and aorta in 8 of 40 of mice; however, no atherosclerotic lesion development was observed. Repeated inoculation of apoE(-/-) mice resulted in a statistically significant increase in lesion area (n=43; P=.05). Although Chlamydia trachomatis disseminated to the aorta, persistent infection was not established and no statistically significant increase in lesion area occurred. These studies suggest that persistent infection of the aorta can lead to inflammatory changes in the absence of hyperlipidemia and accelerate lesion progress in concert with hyperlipidemia.

Cardiac alpha-actin in smooth muscle cells: detection in umbilical cord vessels and in atherosclerotic lesions

Phenotypic modulation of smooth muscle cells (SMC) is a key event during the development of atherosclerotic and restenotic lesions. During this process, the composition of the cytoskeleton is substantially altered, with changes predominantly in actin expression reflecting a shift from smooth muscle alpha-actin to the non-muscle beta-isoform. We now demonstrate that yet another actin isoform, cardiac alpha-actin, is synthesized, de novo, in SMC of various atherosclerotic lesions. Using a highly specific monoclonal antibody against cardiac alpha-actin, we analyzed and compared the accumulation of this actin isoform in diverse SMC by immunofluorescence microscopy and immunoblotting. As expected, cardiac alpha-actin was present in human myocardium but not in healthy SMC of adult aorta, coronary arteries, trabeculae of the spleen, colon, stomach or skeletal muscle. Interestingly, the presence of cardiac alpha-actin was detected in umbilical cord vessels, human myometrium, in atherosclerotic coronary lesions and atherosclerotic lesions from peripheral vascular disease. The distribution of cardiac alpha-actin often paralleled that of cytokeratins 8 and 18, intermediate filament proteins typically found in dedifferentiated SMC. Taken together, the data presented here illustrate the expression of cardiac alpha-actin to be limited to either fetal vessels or those vessels or tissue having suffered damage or atrophy, outside its 'native' environment in the heart. The demonstration of cardiac alpha-actin in SMC of umbilical cord vessels and in atherosclerotic lesions but not in apparently healthy vessels supports the notion that SMC in atherosclerotic lesions exhibit a dedifferentiated phenotype.

Incomplete expansion of Palmaz-Schatz stents despite high-pressure implantation technique: impact on target lesion revascularization

Improved expansion of stents using high-pressure implantation technique with subsequent antiplatelet therapy has improved patient outcome regarding the incidence of subacute stent thrombosis, bleeding complications and restenosis. Whether high-pressure implantation per se guarantees adequate stent expansion remains unclear. The aim of the study was to determine (1) stent expansion after high-pressure implantation technique and (2) whether stent expansion influences rate of target lesion revascularization within 6 months of follow-up. One hundred Palmaz-Schatz stents were implanted in 98 lesions (91 native vessels, 7 graft vessels) of 94 patients using high-pressure implantation technique (balloon pressure 12-20 atm). Stent expansion was investigated using intravascular ultrasound imaging (IVUS). Clinical follow-up of the patients was performed for 6 months. After implantation, stent/mean reference ratio was 0.81 +/- 0.16. Noncompliant balloons used for implantation were chosen by angiographic criteria. Mean balloon/reference ratio was 1.08 +/- 0.22; therefore balloons were not undersized. Additional balloon dilataion using higher pressures and/or larger balloons based on IVUS criteria and subsequent IVUS measurements was performed in 52 patients (55%); in these patients, stent expansion improved from 79 +/- 16 to 91 +/- 15% (mean +/- SD) of average reference areas (p < 0.002). Within the 6 months' clinical follow-up, target lesion revascularization was performed in 19 patients (20%). The only prognostic factors for the development of in-stent restenosis requiring target lesion revascularization were the vessel size (p < 0.05) and the extent of plaque distal to the stents (p < 0.05). Implantation of Palmaz-Schatz stents using high-pressure technique does not guarantee adequate stent expansion. Additional dilatation with higher pressures and/or larger balloons improves stent expansion. The size of the stented vessel and the extent of plaque at the distal stent end (residual outflow stenosis) but not the degree of stent expansion were predictors for target lesion revascularization within 6 months' follow-up.

Intravascular ultrasound and stent implantation: intraobserver and interobserver variability

BACKGROUND

Intravascular ultrasound (IVUS) imaging can be used to optimize implantation of intracoronary stents; the variability of the measurements, however, remains unclear. Our aim in this study was to determine the intraobserver and interobserver variability of IVUS measurements after stent implantation.

METHODS

Ninety-four patients underwent implantation of 100 Palmaz-Schatz stents in 98 lesions (79 de novo and 19 restenotic). IVUS measurements (3.5F, 30 MHz) of proximal and distal reference sections and of the smallest stent lumen were performed by 2 investigators.

RESULTS

Intraobserver and interobserver correlations, respectively, were r = 0.96 and 0.93 for the proximal reference, r = 0.94 and 0.92 for the distal reference, and r = 0.97 and 0.97 for minimal stent lumen. Stent expansion (minimal lumen in the stent/mean reference area) showed a variability of r = 0.80 and 0.70. Taking a cutoff point of 90% for adequacy of stent expansion, observers agreed in only 77% whether the stent was adequately or inadequately expanded.

CONCLUSIONS

IVUS enables reproducible lumen measurements in stents and reference sections. The degree of stent expansion, however, underlies a high measurement variability that can lead to different therapeutic strategies.

Smooth excimer laser coronary angioplasty (SELCA) and conventional excimer laser angioplasty: Comparison of vascular injury and smooth muscle cell proliferation

Although the excimer laser, which utilizes 'non-thermal ablation effects', has achieved encouraging results in early clinical trials, the long-term results have failed to show any advantage over conventional percutaneous transluminal coronary angioplasty (PTCA).A new system, Smooth Excimer Laser Coronary Angioplasty (SELCA), has been developed to reduce the tissue damage in the vessel wall caused by shock waves and vapour bubbles.SELCA (wavelength 308 nm, pulse duration 115 ns, repetition rate 150 Hz and energy density 50 mJ mm(-2)) lowers the amount of shock wave formation and pressure peak amplitude in the surrounding tissue by about eight times when compared to the conventional 308 nm excimer laser (ELCA). In this preclinical evaluation, this new system was compared to ELCA. Fifty New Zealand White rabbits were stimulated by repeated weak DC impulses for a period of 28 days in order to form an atherosclerotic plaque in the right carotid artery. The vessels were excised 3, 7,14 and 28 days after laser irradiation for immunohistochemical analysis.SELCA and ELCA laser treatment lead to a decrease in maximal intimal wall thickness 3 days after intervention (control: 177+/-4 microm; SELCA: 131+/-22microm; ELCA: 120 +/-33microm). In the period between 3 and 28 days, a moderate increase in intimal wall thickness was observed after SELCA treatment compared to a significant increase after ELCA (28 days after intervention: SELCA: 157+/-22microm; ELCA: 274 +/-28microm). Bromodeoxyuridine (BrdU) was applied 18 and 12 h before excision of the vessels in order to determine the percent of cells undergoing DNA synthesis. The percent of BrdU labelled SMC in the intima (control: 13 +/- 2 cells mm(-2)) increased in both groups after 3 days (SELCA: 248 +/- 107 cells mm(-2); ELCA: 162 +/- 41 cells mm(-2)) and 7 days (SELCA: 162+/- 55 cells mm(-2); ELCA: 279 +/- 119 cells mm(-2)).The present results demonstrate that vascular wall injury and increase in intimal wall thickness following SELCA are reduced in comparison to the results achieved with the conventional technique. Further trials are necessary to assess whether these improvements will lead to more favourable long-term results after excimer laser angioplasty.

Dislodgement of a Wiktor stent during intracoronary ultrasound examination

We report a case of stent dislodgement complicating adjuvant intracoronary ultrasound (ICUS) imaging that required emergency coronary bypass grafting. This probably very rare complication gains importance since ICUS is increasingly used to confirm adequate stent expansion and full coverage of the lesion.

Angiographically undetected plaque in the left main coronary artery. Findings of intravascular ultrasound imaging

The absence of angiographic findings despite significant coronary artery disease has been previously described. Possible explanations for the limitation of plaque detection by angiography include compensatory vessel enlargement in face of intracoronary plaque formation, the lack of reference segments in diffuse atherosclerosis as well as technical limitations. Intracoronary ultrasound (ICUS) imaging provides the possibility of direct plaque visualization. We studied angiographically normal left main coronary arteries (LMCA) in 72 patients prior to diagnostic angiography or therapeutic interventions using ICUS (30 MHz). ICUS images were continuously recorded and recalled from memory for morphometric analysis. Lumen area, plaque area and the total vessel area were determined by computer software. ICUS imaging revealed atherosclerotic plaque in 55 of the 72 patients with angiographically normal LMCA (76%). The average plaque area stenosis was 22 +/- 12% (range 3-44%). Total vessel area showed a significant direct correlation with plaque area, indicating compensation of coronary plaque formation. The average percent change in plaque area (difference between maximal and minimal plaque area within the LMCA) was 11 +/- 19%, indicating a diffuse pattern. Measurement of change in lumen area (difference between maximal and minimal lumen area within the LMCA) revealed an average value of 6 +/- 7%. Lumen area of the LMCA was 15.9 +/- 3.2 mm2 in patients with and 17.2 +/- 1.9 mm2 without atherosclerotic plaque (n.s.). Thus, the lack of angiographic changes despite advanced plaque formation in the LMCA could be explained by compensatory vessel enlargement and by diffuse distribution of plaque in the vessel; true lumen narrowings overlooked by angiography seem not to account for the failure of angiography to detect plaque.

Efficacy of low-molecular-weight heparin delivery with the Dispatch catheter following balloon angioplasty in the rabbit iliac artery

Local drug delivery can be achieved with active injection systems or passive contact of a compound with the arterial wall. The Dispatch catheter allows for passive diffusion of drugs from drug compartments while preserving blood flow through the central conduit. The aim of this study was to investigate whether a reduction in neointima formation can be achieved by local delivery of a limited amount of a highly concentrated solution of the low-molecular-weight heparin Reviparin. In 16 New Zealand white rabbits, successful balloon dilatation was performed in both iliac arteries, followed by local delivery of 4 ml Reviparin (1,000 IU/ml). The arteries were harvested at 7, 28, or 56 d following the procedure. The intimal cell layers increased substantially between 7 and 28 d following balloon dilatation with or without local drug delivery. The medial cell layers showed only a little increase. Proliferation of smooth muscle cells reached an early peak after 7 d, with a significantly higher proliferation index following local delivery. The maximum amount of macrophages in the intima and media was detected after 28 d. The lumen area decreased with time and was 0.6 +/- 0.7 mm2 in the local delivery group at 56 d compared with 0.5 +/- 0.5 mm2 in the control group. In conclusion, local delivery of Reviparin with the Dispatch catheter is safe and feasible. However, the infusion of highly concentrated low-molecular-weight heparin over a short period of time did not result in a reduction of neointima formation and restenosis following balloon dilatation in the rabbit iliac artery.

Posttraumatic myocardial infarction with severe coronary intimal dissection documented by intravascular ultrasound

We present a case of posttraumatic myocardial infarction after blunt chest trauma in a previously healthy man. Coronary angiography showed an eccentric occlusion in the midportion of the left anterior descending artery. Subsequent intracoronary ultrasound imaging revealed a severe intimal dissection. The outcome after intracoronary stent placement was excellent. This rare but potentially harmful complication of blunt chest trauma should be kept in mind and coronary angiography performed immediately when coronary occlusion is suspected. Intravascular ultrasound imaging is a helpful tool in the assessment of coronary artery occlusion caused by intimal dissection.

Regional differences in the distribution of the proteoglycans biglycan and decorin in the extracellular matrix of atherosclerotic and restenotic human coronary arteries

Proteoglycans are important constituents of blood vessels and accumulate in various forms of vascular disease. Little is known concerning the proteoglycan composition of restenotic lesions formed after angioplasty and whether the proteoglycan composition of these lesions differs from that of primary atherosclerosis. Accordingly, we sought to characterize the distribution of two proteoglycans, biglycan and decorin, in primary atherosclerotic and restenotic lesions of human coronary arteries. Restenosis (n = 37) and primary (n = 11) lesions obtained from 48 patients by directional atherectomy of human coronary arteries were stained with antibodies against biglycan and decorin. To further characterize the extracellular matrix of restenotic tissues, we studied the co-distribution of these proteoglycans with collagen types I, III, and IV. The loose fibroproliferative tissue seen predominantly in restenosis lesions consistently stained positively for biglycan in patterns of deposition ranging from disseminated to homogeneous. The density and intensity of biglycan staining was correlated with the density of collagen type I and III fiber networks, both of which were observed to interweave among the loose fibroproliferative tissue. The compact connective tissue of primary atherosclerotic plaque was characterized by strong biglycan staining which co-localized with intense collagen type I and III staining. Only basement membrane-like structures rich in collagen type IV demonstrated negative biglycan staining. In contrast, loose fibroproliferative tissue exhibited no significant staining for decorin. Strong immunostaining for decorin, however, was found in primary atherosclerotic plaque. There are thus regional differences in the distribution of extracellular matrix proteoglycans of restenotic and primary human atherosclerotic lesions; these observations suggest that differences established for the biological roles of biglycan and decorin in other organ systems may extend as well to pathologically altered human coronary arteries.

Arterial gene transfer using pure DNA applied directly to a hydrogel-coated angioplasty balloon

Direct arterial gene transfer has been previously achieved using double-balloon catheters and perforated balloons, in most cases facilitated by the use of cationic liposomes or viral vectors. These gene delivery systems, however, have been compromised by issues relating to efficacy and/or safety, and furthermore require that angioplasty be performed independent of gene transfer. We investigated the possibility that arterial gene transfer might be performed during balloon angioplasty by delivery of naked genetic material from a thin coat of hydrogel polymer applied to a standard angioplasty balloon. Transfections with luciferase DNA applied to a hydrogel balloon were performed in rabbit arteries. Luciferase expression 3 days after transfection was tested in three different models: (i) an organ culture model (n = 10); (ii) surgically exposed carotid arteries (n = 14); and (iii) external iliac arteries using a percutaneous approach (n = 13). Supplementary transfections (n = 3), intended to identify the site of arterial transfection, were performed using the gene encoding for nuclear-specific beta-galactosidase (beta-gal). All rabbit arteries transfected with the luciferase gene (37/37; 100%) expressed luciferase activity. Gene expression achieved in vivo, either in the surgically exposed carotid arteries or in the external iliac arteries transfected percutaneously, was quantitatively similar to that achieved in the organ culture model. Reduction in the duration of inflation from 30 min to 1 min had no statistically significant impact on transfection efficiency. Gene expression was documented to persist up to 14 days post percutaneous transfection. Analysis of arteries transfected with nuclear-specific beta-gal showed the presence of the transgene in intimal and subintimal sites. These results demonstrate that vascular gene transfer can be performed successfully without liposomes or viral vectors using DNA applied to a standard angioplasty catheter balloon coated with hydrogel. Percutaneous transfection with a hydrogel-coated balloon permits gene transfer coincident with the angioplasty procedure itself, even with inflations as short as 1 min.