Impact of PTSD treatment on postconcussive symptoms in veterans: A comparison of sertraline, prolonged exposure, and their combination

Many Veterans who served in Iraq and Afghanistan struggle with posttraumatic stress disorder (PTSD) and the effects of traumatic brain injuries (TBI). Some people with a history of TBI report a constellation of somatic, cognitive, and emotional complaints that are often referred to as postconcussive symptoms (PCS). Research suggests these symptoms may not be specific to TBI. This study examined the impact of PTSD treatment on PCS in combat Veterans seeking treatment for PTSD. As part of a larger randomized control trial, 198 Operation Iraqi Freedom, Operation Enduring Freedom, Operation New Dawn (OIF/OEF/OND) Veterans with PTSD received Prolonged Exposure Therapy, sertraline, or the combination. Potential deployment related TBI, PCS, PTSD and depression symptoms were assessed throughout treatment. Linear mixed models were used to predict PCS change over time across the full sample and treatment arms, and the association of change in PTSD and depression symptoms on PCS was also examined. Patterns of change for the full sample and the subsample of those who reported a head injury were examined. Results showed that PCS decreased with treatment. There were no significant differences across treatments. No significant differences were found in the pattern of symptom change based on TBI screening status. Shifts in PCS were predicted by change PTSD and depression. Results suggest that PCS reduced with PTSD treatment in this population and are related to shift in depression and PTSD severity, further supporting that reported PCS symptoms may be better understood as non-specific symptoms.

Trauma-focused therapy retention among military sexual trauma survivors: relationship with veterans' sexual or gender minority identification

Military servicemembers identifying as sexual and gender minorities (SGM) are at increased risk for military sexual trauma (MST) exposure and Post-traumatic Stress Disorder (PTSD). Although evidence-based treatments can reduce symptoms of PTSD, treatment attrition is concerning. Unfortunately, evaluations of such approaches with veterans identifying as SGM are currently restricted to case studies offering limited information regarding treatment completion. Both historic and current contextual factors related to military and mental health practices may uniquely influence minority veterans' treatment engagement in veteran healthcare settings. We explored associations between SGM identification and treatment of MST-focused therapy completion patterns (finishing the full protocol [FP] or receiving minimally adequate care [MAC; defined as attending eight or more sessions]). Veterans (N = 271, 12.5% SGM) enrolled in individual Prolonged Exposure or Cognitive Processing Therapies at a Midwestern veterans hospital system. Those identifying as SGM were more likely than non-identifying peers to complete FP treatment and, even when attrition occurred, they were retained longer. For MAC, the SGM group was as likely as non-SGM peers to be retained. This research suggests SGM veterans represent a notable minority of those seeking treatment in association with MST and do not appear at greater risk for discontinuation from trauma-focused treatment.

Feasibility and Acceptability of Group-Facilitated Prolonged Exposure Therapy for PTSD in VA Residential Rehabilitation Treatment Programs

Prolonged Exposure therapy (PE) is a first-line treatment for posttraumatic stress disorder (PTSD); however, few VA patients receive this treatment. One of the barriers to PE receipt is that it is only available in an individual (one-on-one) format, whereas many VA mental health clinics provide the majority of their psychotherapy services in group format. In particular, PTSD residential rehabilitation treatment programs (RRTPs) offer most programming in group format. Consequently, strategies are needed to improve the scalability of PE by adapting it to fit the delivery setting. The current study was designed to pilot test a group-facilitated format of PE in RRTPs. Thirty-nine Veterans who were engaged in care in the PTSD RRTP at a Midwestern VA were recruited to participate in a Group-facilitated PE protocol. Participants engaged in twelve 90-minute sessions of Group PE over the course of 6 weeks, plus six 60-minute individual sessions for imaginal exposure. Group treatment followed the PE model and consisted of psychoeducation, treatment rationale, and in vivo exposure to reduce trauma-related avoidance and thereby improve PTSD symptoms. PTSD symptoms were measured via the PTSD Checklist for DSM-5 (PCL-5) and depression symptoms were measured via the Patient Health Questionnaire (PHQ-9) at baseline, endpoint (6 weeks), and at 2-month follow-up. Thirty-nine individuals initiated Group-facilitated PE and 34 completed treatment. The average number of group sessions attended was 11 out of 12. Acceptability ratings were high. Mean change (improvement) in the intent-to-treat sample at 2-month follow-up was 20.0 points on the PCL-5 (CI 18.1, 21.9; Cohen's d = 1.1) and 4.8 points on the PHQ-9 (CI 4.1, 5.5, d = .8). These results suggest that adapted evidence-based interventions for PTSD can improve treatment access and efficiency for the RRTP setting. A group-based approach has the potential to improve the scalability of PTSD treatment by reducing required resources. A fully powered trial is now needed to test the effectiveness of Group-facilitated PE in the RRTP setting.

Can families help veterans get more from PTSD treatment? A randomized clinical trial examining Prolonged Exposure with and without family involvement

Background

Posttraumatic stress disorder occurs in as many as one in five combat veterans and is associated with a host of negative, long-term consequences to the individual, their families, and society at large. Trauma-focused treatments, such as Prolonged Exposure, result in clinically significant symptom relief for many. Adherence to these treatments (i.e., session attendance and homework compliance) is vital to ensuring recovery but can be challenging for patients. Engaging families in veterans’ treatment could prove to be an effective strategy for promoting treatment adherence while also addressing long-standing calls for better family inclusion in treatment for posttraumatic stress disorder. This paper describes the methods of a pragmatic randomized controlled trial designed to evaluate if family inclusion in Prolonged Exposure can improve treatment adherence.

Methods

One hundred fifty-six veterans, with clinically significant symptoms of posttraumatic stress disorder, will be randomized to receive either standard Prolonged Exposure or Prolonged Exposure enhanced through family inclusion (Family-Supported Prolonged Exposure) across three different VA facilities. Our primary outcomes are session attendance and homework compliance. Secondary outcomes include posttraumatic stress disorder symptom severity, depression, quality of life, and relationship functioning. The study includes a concurrent process evaluation to identify potential implementation facilitators and barriers to family involvement in Prolonged Exposure within VA.

Discussion

While the importance of family involvement in posttraumatic stress disorder treatment is non-controversial, there is no evidence base supporting best practices on how to integrate families into PE or any other individually focused trauma-focused treatments for posttraumatic stress disorder. This study is an important step in addressing this gap, contributing to the literature for both retention and family involvement in trauma-focused treatments.

Trial registration

ClinicalTrials.govNCT03256227. Registered on August 21, 2017.

Predictors of Response to Prolonged Exposure, Sertraline, and Their Combination for the Treatment of Military PTSD

Objective: The current study is an analysis of predictors of posttraumatic stress disorder (PTSD) treatment response in a clinical trial comparing (1) prolonged exposure plus placebo (PE + PLB), (2) PE + sertraline (PE + SERT), and (3) sertraline + enhanced medication management (SERT + EMM) with predictors including time since trauma (TST), self-report of pain, alcohol use, baseline symptoms, and demographics. Methods: Participants (N = 196) were veterans with combat-related PTSD (DSM-IV-TR) of at least 3 months' duration recruited between 2012 and 2016 from 4 sites in the 24-week PROlonGed ExpoSure and Sertraline (PROGrESS) clinical trial (assessments at weeks 0 [intake], 6, 12, 24, 36, and 52). Results: Across treatment conditions, (1) longer TST was predictive of greater week 24 PTSD symptom improvement (β = 1.72, P = .01) after adjusting for baseline, (2) higher baseline pain severity was predictive of smaller symptom improvement (β = -2.96, P = .003), and (3) Hispanic patients showed greater improvement than non-Hispanic patients (β = 12.33, P = .03). No other baseline characteristics, including alcohol consumption, were significantly predictive of week 24 improvement. Comparison of TST by treatment condition revealed a significant relationship only in those randomized to the PE + SERT condition (β = 2.53, P = .03). Longitudinal analyses showed similar results. Conclusions: The finding that longer TST shows larger symptom reductions is promising for PTSD patients who might not seek help for years following trauma. Higher baseline pain severity robustly predicted attenuated and slower response to all treatment conditions, suggesting a common neuropathologic substrate. Finally, in the current study, alcohol use did not impede the effectiveness of pharmacotherapy for PTSD. Trial Registration: ClinicalTrials.gov identifier: NCT01524133.

Neural function during emotion processing and modulation associated with treatment response in a randomized clinical trial for posttraumatic stress disorder

BACKGROUND

Posttraumatic stress disorder (PTSD) has been associated with exaggerated threat processing and deficits in emotion modulation circuitry. It remains unknown how neural circuits are associated with response to evidence-based treatments for PTSD.

METHOD

We examined associations between PTSD symptoms and indicators of neural response in key emotion processing and modulation regions. Fifty-six military Veterans with PTSD were randomly assigned to one of three evidence-based treatments (prolonged exposure, sertraline, and PE plus sertraline) in a randomized clinical trial ("PROGrESS"; 2018, Contemp Clin Trials, 64, 128-138). Twenty-seven combat-exposed controls (CCs) served as a comparison group at pretreatment. Before and after PTSD treatment, functional magnetic resonance imaging was used to assess brain activation and connectivity during the validated Shifted Attention Emotion Appraisal Task (2003, J Neurosci, 23, 5627-5633; 2013, Biol Psychiatry, 73, 1045-1053).

RESULTS

Greater activation in emotion processing (anterior insula) and modulation (prefrontal cortex) regions and increased connectivity between attentional control (dorsolateral prefrontal cortex and superior parietal cortex) and emotion processing (amygdala) regions, at pretreatment, were associated with subsequent PTSD symptom improvement.

CONCLUSIONS

This study is one of the first to examine task-based activation and functional connectivity in a PTSD treatment trial, and provides evidence to suggest that activation in and connectivity between emotion processing and modulation regions are important predictors of treatment response.

Neural correlates of emotional reactivity and regulation associated with treatment response in a randomized clinical trial for posttraumatic stress disorder

Posttraumatic Stress Disorder (PTSD) is a debilitating condition often associated with difficulty in emotion regulation, including reappraising negative emotions. This study assessed neural mechanisms associated with emotion regulation in veterans prior to and following treatment for PTSD. Participants with PTSD and combat exposed controls (CC) completed diagnostic evaluation and underwent fMRI scanning while completing Emotion Regulation Task (ERT) and Emotional Faces Assessment Task (EFAT). Participants with PTSD were randomly assigned to Prolonged Exposure plus placebo (PE+PLB), Sertraline plus enhanced medication management (SERT+EMM), or PE plus SERT (PE+SERT) and repeated diagnostic evaluation and MRI scanning following treatment. The amygdala, dmPFC, and dlPFC were examined as regions of interest. On ERT, veterans with PTSD showed significantly less dmPFC activation than CCs during reappraisal vs emotional maintenance. Within the PTSD group, results demonstrated a significant association between less activation in the dmPFC during emotion reappraisal vs maintenance trials before treatment and greater reductions in symptoms from pre- to post-treatment. During the EFAT, there were no group differences between participants with PTSD and CCs in brain activation, and no relationships between brain function and PTSD symptoms. These findings suggest that less emotional reactivity might potentially reflect less need for recruitment of prefrontal regions when reappraising negative emotion, and is an individual factor associated with better treatment outcome.

PTSD as a Mediator in the Relationship Between Post-Concussive Symptoms and Pain Among OEF/OIF/OND Veterans

Introduction

Traumatic brain injury (TBI), pain, and post-traumatic stress disorder (PTSD) commonly co-occur in Veteran populations, particularly among Veterans returning from the recent conflicts in Iraq and Afghanistan. Extant research indicates that both TBI and PTSD can negatively impact pain broadly; however, less is known about how these variables impact one another. The current study examines the impact of self-reported post-concussive symptoms on both pain severity and pain interference among Veterans with PTSD who screened positive for a possible TBI, and subsequently, evaluates the potential mediating role of PTSD in these relationships.

Materials and Methods

Participants were 126 combat Veterans that served in Operation Enduring Freedom, Operation Iraqi Freedom, or Operation New Dawn who were being evaluated for participation in a multisite treatment outcomes study. As part of an initial evaluation for inclusion in the study, participants completed several self-report measures and interviews, including the Brief Traumatic Brain Injury Screen, Neurobehavioral Symptom Inventory, Brief Pain Inventory, and the Clinician Administered PTSD Scale, which were utilized in these analyses.

Results

For pain severity, greater post-concussive symptoms significantly predicted increased pain severity with a significant indirect effect of post-concussive symptoms on pain severity through PTSD (indirect effect = 0.03; 95% confidence interval = 0.0094-0.0526). Similar results were found for pain interference (indirect effect = 0.03; 95% confidence interval = 0.0075-0.0471).

Conclusions

These findings replicate and extend previous findings regarding the relationship between TBI, pain, and PTSD. Self-reported post-concussive symptoms negatively impact both pain severity and pain interference among Veterans with probable TBI, and PTSD serves as a mediator in these relationships. Clinically, these results highlight the importance of fully assessing for PTSD symptoms in Veterans with a history of TBI presenting with pain. Further, it is possible that providing effective PTSD treatment to reduce PTSD severity may provide some benefit in reducing post-concussive and pain symptoms.

Context Matters: Posttraumatic Stress Disorder Symptom Associations With Military Sexual Trauma Event Characteristics and Dual Histories of Interpersonal Trauma

Despite the high rates of military sexual trauma (MST) experienced by service members and veterans, little is known about how contextual features of the MST event or concurrent histories of other interpersonal traumas are associated with diverse clinical presentations. This study examined contextual factors of MST events (number of perpetrators, location of MST, relationship to perpetrator, location of MST) and dual history of interpersonal traumas (including sexual abuse or assault throughout the lifespan, repeated MST, and intimate partner violence) in relation to total symptoms and symptom clusters of Posttraumatic Stress Disorder (PTSD). MST involving multiple perpetrators was related to higher avoidance and hyperarousal. MST while combat-deployed was associated with higher hyperarousal. Veterans endorsing a history of partner violence presented with higher reexperiencing and avoidance. Recognition of phenotypic differences may assist providers in treatment planning and optimizing outcomes.

Relation between sexual and gender minority status and suicide attempts among veterans seeking treatment for military sexual trauma

There is limited study of suicidal behaviors among veterans identifying as sexual and gender minorities (SGMs), despite previous research indicating rates of suicide attempts are high within civilian SGM populations. Further, some research incorporating military service members suggests those identifying as SGMs are disproportionately exposed to military sexual trauma (MST), an additional risk factor for negative psychiatric sequelae. To address health care research disparities among minority veterans (i.e., women, those endorsing MST, SGMs), we examined presentations of veterans (N = 277) who attended initial consultation appointments for MST-related treatment and completed a semistructured clinical interview including demographic characteristics, history of suicide attempts (HSA), and a diagnostic evaluation. Twenty-eight (10.1%) veterans identified as SGMs. SGM/non-SGM groups were contrasted on suicidal and psychiatric morbidity outcomes. Overall, endorsement of HSA was high (30.7%). Despite similar clinical profiles, 53.6% of veterans who identified as SGM endorsed HSA in contrast with 28.1% of peers identifying as heterosexual and nontransgender, a significant effect of small-to-moderate size. Findings suggest assessment and clinical management of suicidality is of critical importance for clinicians providing services to veterans pursuing recovery from MST, generally, and may be especially so when delivering care to SGM. Further, results underscore the need for culturally competent delivery of trauma-focused interventions. (PsycINFO Database Record

Postconcussive symptoms (PCS) following combat-related traumatic brain injury (TBI) in Veterans with posttraumatic stress disorder (PTSD): Influence of TBI, PTSD, and depression on symptoms measured by the Neurobehavioral Symptom Inventory (NSI)

Mild traumatic brain injury (mTBI) is commonly reported in recent combat Veterans. While the majority resolve, some Veterans develop postconcussive symptoms (PCS). Previous research suggests these symptoms are not specific to head injury and are often associated with psychiatric symptoms. The current study examines the relative contributions of posttraumatic stress, depressive symptoms, and TBI on postconcussive symptoms, and explores whether the relationship remains after controlling for symptom overlap. Two hundred eighteen combat Veterans from Operation Iraqi Freedom (OIF), Operation Enduring Freedom (OEF), and Operation New Dawn (OND) provided the data for this study as part of a baseline evaluation for inclusion into larger treatment study for posttraumatic stress disorder (PTSD). Participants completed the Brief Traumatic Brain Injury Screen (BTBIS), Neurobehavioral Symptom Inventory (NSI), PTSD Checklist-Stressor Version (PCL-S), Beck Depression Inventory-II (BDI-II). Significant differences in NSI total score between individuals with and without history of TBI were not found. A series of regression analyses demonstrated that Depression and PTSD were significant predictors of NSI score even after removal of NSI symptoms that overlap with PTSD or depression. TBI status was also a significant predictor of PCS in most models, but its relative contribution was much smaller than that of depression and PTSD. Within PTSD symptoms, hyperarousal cluster was a significant predictor of NSI scores. Findings demonstrate that depression and PTSD are related to PCS beyond similarities in construct. Further, within a primarily PTSD treatment-seeking population, these psychiatric symptoms appear to be a stronger contributor than TBI.

Trauma related guilt cognitions partially mediate the relationship between PTSD symptom severity and functioning among returning combat veterans

Trauma related guilt, a distressing emotion associated with negative cognitions regarding one's actions or inaction during a traumatic event, is common among individuals with posttraumatic stress disorder (PTSD). We hypothesized that trauma related guilt cognitions would partially explain the relationship between PTSD symptom severity and functioning. The sample consisted of 254 combat veterans or active duty military personnel who served in Operation Enduring Freedom, Operation Iraqi Freedom or Operation New Dawn (OEF/OIF/OND) who consented to participate in a larger PTSD treatment study. Results revealed a significant relationship between PTSD severity and guilt cognitions (standardized β = 0.40), as well as PTSD and overall functioning (β = 0.49). Guilt cognitions (β's = 0.13 to 0.32) were significantly associated with nearly all domains of functioning, including overall functioning (β = 0.27), and partially explained the relationship between PTSD and functioning. This study lends support to the addition of guilt as a symptom of PTSD in the DSM-5 as it contributes significantly to functional impairment even when accounting for other symptoms of PTSD, although co-occurring mental health problems may also contribute to functional impairments associated with PTSD. Future studies are needed to investigate whether reductions in traumatic guilt are related to improved functional outcomes in PTSD treatments.

The Role of Big Endothelin-1 in Colorectal Cancer

Introduction

Changes in liver blood flow caused by an unknown splanchnic vasoconstrictor have been noted in colorectal cancer patients with liver metastases. This prospective study was performed to assess whether plasma levels of big endothelin-1 (big ET-1) were raised in patients with colorectal cancer.

Methods

Plasma samples from peripheral vein of patients who underwent surgery for primary colorectal cancer (n=60) and those with known colorectal liver metastases (n=45) for a period of 15 months were taken prior to treatment and compared to age- and sex-matched controls (n=20). Plasma samples were analysed by using a single-step sandwich enzyme immunoassay. Immunohistochemistry and in situ hybridisation were also performed on tumour sections to investigate the expression of ET-1 by cancer cells.

Results

The median (range) plasma concentration of big ET-1 in controls was 2.1 pg/mL (1.2–13.4 pg/mL). The median (range) plasma concentration of big ET-1 in colorectal cancer patients with no overt hepatic metastases was 3.8 pg/mL (1.2–15.8 pg/mL), p=0.002, and the median (range) plasma concentration of big ET-1 in colorectal cancer patients with hepatic metastases was 5.2 pg/mL (1.7–30 pg/mL), p=0.0001; both were significantly elevated compared to the control group. A significant difference in immunostaining for big ET-1 was noted between paired normal colonic mucosa (median score-1) and tumour sections (median score-3), p=0.01.

Conclusion

This study has demonstrated elevated concentrations of big ET-1 in colorectal cancer patients, especially in those with hepatic metastases. Upregulation of ET activity in colorectal cancer could be inferred by the increased immunostaining of big ET-1 in cancer cells. Therefore, plasma big ET-1 levels should be evaluated as a potential tumour marker for the identification of hepatic metastases at an earlier stage.

Sleep disturbances as predictors of prolonged exposure therapy effectiveness among veterans with PTSD

Sleep disturbances (SD) are pronounced in Veterans with posttraumatic stress disorder (PTSD). In clinical trials, SD have been shown to limit the effectiveness of evidence-based treatments for non-PTSD disorders. The purpose of this study was to investigate the relationships between pretreatment SD and the effectiveness of Prolonged Exposure (PE) therapy for Veterans with PTSD. Twenty-one Veterans completed the Pittsburgh Sleep Quality Index (PSQI) and the Clinician Administered PTSD Scale upon presenting to a PTSD specialty clinic. Veterans completed the PTSD Symptom Checklist-Civilian (PCL-C) at the initiation of PE and biweekly thereafter for the duration of treatment (96 total assessments). Correlations and hierarchical linear modeling were utilized to examine the potential impact of baseline sleep variables on the slope and magnitude of treatment outcomes. Higher PSQI total scores, and higher sleep latency and sleep medication use subscale scores were associated with higher PCL-C scores at baseline. Veterans evidenced significant reductions in PTSD symptoms during the course of the treatment study. Total PSQI scores and composites were not associated with reduced effectiveness of PE treatment or the slope of PTSD symptom changes. Sleep disturbances do not preclude Veterans from benefits derived from engagement in this gold standard PTSD intervention.

Posttraumatic stress disorder and somatic complaints: Contrasting Vietnam and OIF/OEF Veterans' experiences

OBJECTIVE

To replicate and expand upon the relationship of somatic symptoms and posttraumatic stress disorder (PTSD) by comparing symptoms among service eras in US Veterans.

METHOD

Data were collected from 226 Vietnam and 132 Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) Veterans who were referred to a Veterans Affairs (VA) hospital PTSD outpatient clinic between 2005 and 2013. Veterans were administered self-report inventories and a clinical interview to measure somatic symptoms and PTSD severity. A subset of Veterans (n=185) screening positive for PTSD were administered the Clinician Administered PTSD Scale (CAPS) to measure PTSD severity. Multiple moderated linear regressions were used to examine the influence of service era on the relationship between somatic and PTSD symptoms.

RESULTS

There were no significant differences between service eras in pain severity, pain interference, and total somatic symptoms reported. Vietnam Veterans were more likely to report limb/join pain (p<.05), fainting (p<.01), and shortness of breath (p<.001), whereas OIF/OEF Veterans were more likely to complain of headaches (p<.001). A significant interaction effect occurred between service era and dizziness (p<.05) and chest pain (p<.01), with OIF/OEF Veterans reporting higher levels of these symptoms significantly more likely than Vietnam Veterans to also experience more severe PTSD.

CONCLUSION

Findings are consistent with previous research demonstrating the relationship of somatic symptoms and PTSD across service eras but provide additional data concerning similarities and differences of somatic symptoms between eras. Potential explanations for observed service era differences in somatic symptoms are discussed.

A Pilot Study of Mindfulness-Based Exposure Therapy in OEF/OIF Combat Veterans with PTSD: Altered Medial Frontal Cortex and Amygdala Responses in Social-Emotional Processing

Combat-related posttraumatic stress disorder (PTSD) is common among returning veterans, and is a serious and debilitating disorder. While highly effective treatments involving trauma exposure exist, difficulties with engagement and early drop may lead to sub-optimal outcomes. Mindfulness training may provide a method for increasing emotional regulation skills that may improve engagement in trauma-focused therapy. Here, we examine potential neural correlates of mindfulness training and in vivo exposure (non-trauma focused) using a novel group therapy [mindfulness-based exposure therapy (MBET)] in Afghanistan (OEF) or Iraq (OIF) combat veterans with PTSD. OEF/OIF combat veterans with PTSD (N = 23) were treated with MBET (N = 14) or a comparison group therapy [Present-centered group therapy (PCGT), N = 9]. PTSD symptoms were assessed at pre- and post-therapy with Clinician Administered PTSD scale. Functional neuroimaging (3-T fMRI) before and after therapy examined responses to emotional faces (angry, fearful, and neutral faces). Patients treated with MBET had reduced PTSD symptoms (effect size d = 0.92) but effect was not significantly different from PCGT (d = 0.43). Improvement in PTSD symptoms from pre- to post-treatment in both treatment groups was correlated with increased activity in rostral anterior cingulate cortex, dorsal medial prefrontal cortex (mPFC), and left amygdala. The MBET group showed greater increases in amygdala and fusiform gyrus responses to Angry faces, as well as increased response in left mPFC to Fearful faces. These preliminary findings provide intriguing evidence that MBET group therapy for PTSD may lead to changes in neural processing of social-emotional threat related to symptom reduction.

Prolonged Exposure for PTSD in a Veteran group: a pilot effectiveness study

Previous research has consistently demonstrated that Prolonged Exposure (PE) therapy is an effective treatment for posttraumatic stress disorder (PTSD). Traditionally, PE has been studied and delivered on an individual basis. However, the growing number of Veterans in need of PTSD treatment has led to increased interest in group therapies as an efficient way to provide access to care. The current study examined a group and individual hybrid treatment that was developed based on PE principles. Treatment was 12 weeks in length and consisted of 12 one-hour group sessions focused on in vivo exposures, and an average of approximately five-hour long individual imaginal exposure sessions. Data for this study were derived from 67 veterans who participated in 12 cohorts of the Group PE. Significant reductions in PTSD and depression symptoms were found in both completers and intent-to-treat sample analyses. The clinical implications of these findings are discussed.

PTSD and pain: exploring the impact of posttraumatic cognitions in veterans seeking treatment for PTSD

OBJECTIVE

Previous research has demonstrated a significant relationship between posttraumatic stress disorder (PTSD) and pain. While several models attempt to explain this relationship, significant questions remain regarding factors that may play a role in this interaction. The purpose of this study was to determine whether posttraumatic cognitions mediate the relationship between PTSD and pain.

DESIGN

The sample comprised 136 veterans who presented to the VA Ann Arbor Health Care System seeking evaluation and treatment in the PTSD clinic. Participants completed the Clinician-Administered PTSD Scale, the Posttraumatic Cognitions Inventory, and Brief Pain Inventory-Short Form, along with other assessments as part of their evaluation.

RESULTS

This study showed that the majority of patients (86.8%) reported some problems with pain. Further, the findings indicate that there is a significant relationship between PTSD severity and pain severity. Posttraumatic cognitions were not related to the level of pain experienced, but they were related to pain interference in this population.

CONCLUSIONS

In particular, negative cognitions regarding the self were associated with the level of pain-related interference, and partially mediated the relationship between PTSD and pain. The clinical implications of these findings are discussed.

Anger, dissociation, and PTSD among male veterans entering into PTSD treatment

Prior research suggests that dissociation and anger are risk factors for the development of posttraumatic stress disorder (PTSD). Research found that trauma survivors with higher levels of anger also report more severe PTSD overall. Studies also support a relationship between PTSD severity and dissociation. Only one prior study of sexual assault survivors by Feeny, Zoellner, and Foa (2000) examined the relationships among dissociation, anger, and PTSD. While Veterans have been found to report high levels of anger and dissociation, the relationship between these factors and PTSD has not been examined among Veterans. This paper examines the relationship among anger, dissociation, and PTSD in treatment-seeking Veterans who presented for evaluation at the PTSD Clinic in the VA Ann Arbor Healthcare System during a four year period. Anger and dissociation predicted PTSD, hyperarousal, and avoidance/numbing severity while dissociation predicted intrusive severity. The implications of these results for clinical practice are discussed.

Stereo-selective inhibition of transient receptor potential TRPC5 cation channels by neuroactive steroids

BACKGROUND AND PURPOSE

Transient receptor potential canonical 5 (TRPC5) channels are widely expressed, including in the CNS, where they potentiate fear responses. They also contribute to other non-selective cation channels that are stimulated by G-protein-coupled receptor agonists and lipid and redox factors. Steroids are known to modulate fear and anxiety states, and we therefore investigated whether TRPC5 exhibited sensitivity to steroids.

EXPERIMENTAL APPROACH

Human TRPC5 channels were conditionally expressed in HEK293 cells and studied using intracellular Ca²⁺ measurement, whole-cell voltage-clamp and excised patch techniques. For comparison, control experiments were performed with cells lacking TRPC5 channels or expressing another TRP channel, TRPM2. Native TRPC channel activity was recorded from vascular smooth muscle cells.

KEY RESULTS

Extracellular application of pregnenolone sulphate, pregnanolone sulphate, pregnanolone, progesterone or dihydrotestosterone inhibited TRPC5 activity within 1–2 min. Dehydroepiandrosterone sulphate or 17β-oestradiol had weak inhibitory effects. Pregnenolone, and allopregnanolone, a progesterone metabolite and stereo-isomer of pregnanolone, all had no effects. Progesterone was the most potent of the steroids, especially against TRPC5 channel activity evoked by sphingosine-1-phosphate. In outside-out patch recordings, bath-applied progesterone and dihydrotestosterone had strong and reversible effects, suggesting relatively direct mechanisms of action. Progesterone inhibited native TRPC5-containing channel activity, evoked by oxidized phospholipid.

CONCLUSIONS AND IMPLICATIONS

Our data suggest that TRPC5 channels are susceptible to relatively direct and rapid stereo-selective steroid modulation, leading to channel inhibition. The study adds to growing appreciation of TRP channels as non-genomic steroid sensors.

Cellular mechanisms by which proinsulin C-peptide prevents insulin-induced neointima formation in human saphenous vein

AIMS/HYPOTHESIS

Endothelial cells (ECs) and smooth muscle cells (SMCs) play key roles in the development of intimal hyperplasia in saphenous vein (SV) bypass grafts. In diabetic patients, insulin administration controls hyperglycaemia but cardiovascular complications remain. Insulin is synthesised as a pro-peptide, from which C-peptide is cleaved and released into the circulation with insulin; exogenous insulin lacks C-peptide. Here we investigate modulation of human SV neointima formation and SV-EC and SV-SMC function by insulin and C-peptide.

METHODS

Effects of insulin and C-peptide on neointima formation (organ cultures), EC and SMC proliferation (cell counting), EC migration (scratch wound), SMC migration (Boyden chamber) and signalling (immunoblotting) were examined. A real-time RT-PCR array identified insulin-responsive genes, and results were confirmed by real-time RT-PCR. Targeted gene silencing (siRNA) was used to assess functional relevance.

RESULTS

Insulin (100 nmol/l) augmented SV neointimal thickening (70% increase, 14 days), SMC proliferation (55% increase, 7 days) and migration (150% increase, 6 h); effects were abrogated by 10 nmol/l C-peptide. C-peptide did not affect insulin-induced Akt or extracellular signal-regulated kinase signalling (15 min), but array data and gene silencing implicated sterol regulatory element binding transcription factor 1 (SREBF1). Insulin (1-100 nmol/l) did not modify EC proliferation or migration, whereas 10 nmol/l C-peptide stimulated EC proliferation by 40% (5 days).

CONCLUSIONS/INTERPRETATION

Our data support a causative role for insulin in human SV neointima formation with a novel counter-regulatory effect of proinsulin C-peptide. Thus, C-peptide can limit the detrimental effects of insulin on SMC function. Co-supplementing insulin therapy with C-peptide could improve therapy in insulin-treated patients.

Diabetes and the abdominal aortic aneurysm

OBJECTIVE

The aim of this review is to delineate the association between abdominal aortic aneurysms (AAAs) and diabetes mellitus. Mechanisms for the underlying association are then discussed.

METHODS

A systematic review of the English-language literature using PubMed, EMBASE and Cochrane databases was undertaken up to September 2009. Studies reporting appropriate prevalence data were identified and a meta-analysis performed.

RESULTS

Eleven studies were identified. The prevalence of diabetes mellitus in studied patients with AAA ranged from 6% to 14%. The prevalence of diabetes in control patients without AAA ranged from 17% to 36%. Pooled analysis suggested a reduced rate of diabetes amongst people with AAA compared to those without (OR 0.65, 0.60-0.70, p<0.001).

CONCLUSIONS

Studies so far suggest a protective role for diabetes on the development of AAA. Further research is required to demarcate the underlying mechanisms for this possible association.

Upregulated TRPC1 channel in vascular injury in vivo and its role in human neointimal hyperplasia

Occlusive vascular disease is a widespread abnormality leading to lethal or debilitating outcomes such as myocardial infarction and stroke. It is part of atherosclerosis and is evoked by clinical procedures including angioplasty and grafting of saphenous vein in bypass surgery. A causative factor is the switch in smooth muscle cells to an invasive and proliferative mode, leading to neointimal hyperplasia. Here we reveal the importance to this process of TRPC1, a homolog of Drosophila transient receptor potential. Using 2 different in vivo models of vascular injury in rodents we show hyperplasic smooth muscle cells have upregulated TRPC1 associated with enhanced calcium entry and cell cycle activity. Neointimal smooth muscle cells after balloon angioplasty of pig coronary artery also express TRPC1. Furthermore, human vein samples obtained during coronary artery bypass graft surgery commonly exhibit an intimal structure containing smooth muscle cells that expressed more TRPC1 than the medial layer cells. Veins were organ cultured to allow growth of neointimal smooth muscle cells over a 2-week period. To explore the functional relevance of TRPC1, we used a specific E3-targeted antibody to TRPC1 and chemical blocker 2-aminoethoxydiphenyl borate. Both agents significantly reduced neointimal growth in human vein, as well as calcium entry and proliferation of smooth muscle cells in culture. The data suggest upregulated TRPC1 is a general feature of smooth muscle cells in occlusive vascular disease and that TRPC1 inhibitors have potential as protective agents against human vascular failure.

Hypoxic regulation of Ca2+ signalling in astrocytes and endothelial cells

Acute hypoxia is well known to modulate plasmalemmal ion channels in specific tissue types, thereby modulating [Ca2+]i. Alternative mechanisms by which acute hypoxia could modulate [Ca2+]i are less well explored, particularly in non-excitable cells. Here, we describe experiments employing microfluorimetric recordings from Fura-2-loaded rat cortical astrocytes and human saphenous vein endothelial cells designed to explore any effects of hypoxia (pO2 20-30 mmHg) on [Ca2+]i. In both cell types, hypoxia evoked small rises of [Ca2+]i in the majority of cells during perfusion with a Ca(2+)-free solution, indicating hypoxia can release Ca2+ from an intracellular pool. Capacitative Ca2+ entry was observed when Ca2+ was subsequently restored to the extracellular solution. These effects were abolished by pre-treatment of cells with thapsigargin or prior application of inositol 1,4,5-trisphosphate (IP3)-generating agonists. Antioxidants fully prevented this effect of hypoxia in both cell types. Mitochondrial uncoupling significantly enhanced the effects of hypoxia in astrocytes, yet markedly suppressed the effects of hypoxia in endothelial cells. Our findings indicate that hypoxia can modulate [Ca2+]i in non-excitable cells; most importantly, it can evoke Ca2+ release from intracellular stores via a mechanism which involves reactive oxygen species. The involvement of mitochondria in this effect appears to be tissue specific.

The Effect of Six Different Statins on the Proliferation, Migration, and Invasion of Human Smooth Muscle Cells

Intimal hyperplasia (IH) can occur after any vascular injury and results from smooth muscle cells (SMC) proliferation, migration, and invasion into the subintimal space. The purpose of this study was to investigate the effect of six different statins on the proliferation, migration, and invasion of human venous SMC. The statins were all used at their Cmax concentrations. SMCs were used to construct growth curves in the presence of 10% fetal calf serum or 10% fetal calf serum supplemented with the six statins. Migration and invasion experiments were performed using modified Boyden chambers. The invasion experiments were performed using Matrigel coated plates. We found that all of the statins significantly inhibited SMC proliferation compared to the platelet-derived growth factor control (ranging from fluvastatin 33% of control to pravastatin 72% of control, P = 0.03). SMC migration through uncoated polycarbonate membranes in presence of the six statins was significantly reduced (ranging from lovastatin 43% to pravastatin 57% of control, P = 0.006). All six statins also significantly reduced SMC invasion (ranging from fluvastatin 65% to simvastatin 87% of control, P = 0.002). We conclude that the inhibitory effect of statins on SMC proliferation, migration, and invasion is a class, rather than drug specific effect.

A Comparison of Six Statins on the Development of Intimal Hyperplasia in a Human Vein Culture Model

OBJECTIVE

Intimal hyperplasia (IH) threatens the patency of up to 35% of saphenous vein (SV) bypass grafts. In addition to reducing cholesterol levels, statins may modulate smooth muscle cell proliferation and migration. Statins inhibit matrix metalloproteinase (MMP) activity. We therefore investigated the effect of six statins on neointimal formation and MMP activity in human SV organ culture.

STUDY DESIGN

Human SV specimens were cultured for 14 days in the presence of six different statins and subsequently processed for measurement of neointimal thickness and MMP activity. The drug concentrations chosen corresponded to the manufacturers' Cmax.

RESULTS

The six statins all significantly reduced IH development (P = 0.004) in association with reduced expression of proMMP-2 and 9 (P = 0.03) and reduced activity of activated MMP-2 and 9 (P = 0.03).

CONCLUSION

This study suggests that the potential benefit of statins in reducing IH is a class effect and not confined to specific statins. The reduction of IH produced by statins may in part be due to their inhibition of MMPs.

Enhanced invasive properties exhibited by smooth muscle cells are associated with elevated production of MMP-2 in patients with aortic aneurysms

BACKGROUND

abdominal aortic aneurysms (AAA) are associated with excessive vascular matrix remodelling. Recent findings suggest a systemic overproduction of matrix metalloproteinases-2 (MMP-2) by vascular smooth muscle cells (SMC) may be pivotal aetiologically. SMC migration is facilitated by MMP mediated proteolysis of the basement membrane and extracellular matrix. Our aim was to see if enhanced MMP-2 production by these SMC exhibit increased invasion, in an in vitro model of migration.

METHOD

SMC were derived from inferior mesenteric vein (IMV) harvested from patients undergoing aneurysm repair (n=6) or colectomy for diverticulosis (n=6, control). Using a modified Boyden chamber chemotaxis was measured towards platelet derived growth factor (PDGF) and foetal calf serum (FCS) and invasion through a Matrigel layer. MMP-2 production was quantified by ELISA and gelatin zymography.

RESULTS

chemoattractant studies demonstrated no difference in the effect of PDGF or FCS between the two populations of SMC. However, invasive studies demonstrated a significant increase in the number of migrating SMC isolated from IMV of AAA patients. Analysis of culture media extracts revealed that this difference was associated with a significant increase in production of MMP-2.

CONCLUSION

SMC derived from patients with AAA demonstrate increased invasive properties when compared to a control group. Increased migration appears to be due to overproduction of MMP-2. The enhanced migratory potential of these SMC may lead to extracellular matrix remodelling and subsequent medial disruption demonstrated in the aneurysmal aorta. These data further support evidence of the proteolytic role of MMP-2 in cell migration.

Statins for the prevention of vein graft stenosis: a role for inhibition of matrix metalloproteinase-9

Saphenous vein (SV) grafts are commonly used to bypass coronary arteries that are diseased due to atherosclerosis. However, the development of intimal hyperplasia in such grafts can lead to patency-threatening stenosis and re-occlusion of the vessel. The proliferation and migration of smooth muscle cells (SMC) play key roles in the development of intimal hyperplasia, and an agent that inhibits both of these processes therefore has therapeutic potential. A prerequisite for SMC proliferation and migration in vivo is degradation of the basement membrane, achieved by secretion of the matrix-degrading gelatinases matrix metalloproteinase-2 (MMP-2) and MMP-9. Statins are cholesterol-lowering drugs that also have direct effects on SMC function. Here we report that neointima formation in organ-cultured human SV segments is inhibited by simvastatin, an effect that is associated with reduced MMP-9 activity. Additionally, our work shows that simvastatin not only inhibits proliferation, but importantly also inhibits invasion (migration through a matrix barrier), of cultured human SV SMC. Thus simvastatin treatment appears to inhibit neointima formation as a result of combined inhibition of SMC proliferation and invasion. The potential intracellular mechanisms by which statins affect SMC proliferation and migration, and thus attenuate intimal hyperplasia, are discussed, with particular emphasis on the role of MMP-9.

Inhibition of neointima formation in an organ culture of human saphenous vein: a comparison of dual endothelin-converting enzyme/neutral endopeptidase and selective neutral endopeptidase inhibition

PURPOSE

Endothelin-1 (ET-1) has been implicated in a variety of vascular pathologic conditions, although there is considerable controversy as to whether such effects are mediated by the ET-(A) or ET-(B) receptor. This study investigated whether inhibition of big ET-1 processing by inhibition of endothelin-converting enzyme (ECE) could, therefore, offer an alternative therapeutic strategy in the prevention of vein graft intimal hyperplasia.

METHODS

Human saphenous vein (3 equal segments from 10 patients) were maintained in organ culture for 14 days with either 50 micromol/L CGS 26303 (a dual ECE/neutral endopeptidase [NEP] inhibitor), 50 micromol/L CGS 24592 (a selective NEP inhibitor), or vehicle (control). They were then processed for immunostaining and neointimal thickness measurements, and conditioned media was collected for enzyme-linked immunosorbent assay analysis.

RESULTS

Neointimal thickness in the ECE/NEP-inhibited veins did not differ significantly from that of control segments. However, there was a highly significant augmentation in the NEP-inhibited segments, consistent with an inhibition of ET-1 degradation (median difference, 16.8; 95% CI, -23.5, -10.4; P =.002, Wilcoxon). ECE immunostaining was reduced in the ECE/NEP-inhibited veins, although ET-1 staining was also present. ET-1 expression was intense in the thickened neointimas of NEP-inhibited veins, which also showed significant ECE staining. Elevated levels of big ET-1 were measured in the ECE/NEP-inhibited veins, consistent with reduced ECE activity. However, mature ET-1 was still detectable in these segments.

CONCLUSION

There is a requirement for potent and selective inhibitors of ECE to evaluate fully the potential therapeutic benefits of blocking ET-1 biosynthesis. The use of dual inhibitors complicates the interpretation of results, because the observed response is likely to be a combination of both ECE and NEP inhibition.

Antiproliferative effect of UTP on human arterial and venous smooth muscle cells

We have investigated the hypothesis that responses associated with proliferation are regulated by extracellular nucleotides such as ATP and UTP in cultured human vascular smooth muscle cells (VSMC) derived from internal mammary artery (IMA) and saphenous vein (SV). Platelet-derived growth factor (PDGF), ATP, and UTP each generated an increase in cytosolic free Ca(2+) concentration ([Ca(2+)](i)) in both IMA- and SV-derived cells in the absence of detectable inositol 1,4,5-trisphosphate production. ATP alone had no effect on [(3)H]thymidine incorporation into DNA, but with a submaximal concentration of PDGF it raised [(3)H]thymidine incorporation in SV- but not IMA-derived cells. UTP alone also was without effect on [(3)H]thymidine incorporation or cell number. However, in both SV- and IMA-derived cells, UTP reduced the PDGF-stimulated [(3)H]thymidine response and PDGF-stimulated cell proliferation. This cannot be explained by an inhibitory effect on the p42/p44 mitogen-activated protein kinase (MAPK) cascade, since this response to PDGF was not attenuated by UTP. We conclude that, in human VSMC of both arterial and venous origin, UTP acts as an anti-proliferative regulator.

Raised levels of plasma big endothelin 1 in patients with colorectal cancer

BACKGROUND

The aim was to assess the role of plasma Big Endothelin (ET) 1 levels as a marker of disease presence and stage in colorectal adenocarcinoma.

METHODS

Big ET-1 was measured in the plasma of 37 patients with colorectal cancer. Preoperative systemic plasma levels of Big ET-1 in patients with cancer were compared with levels in 20 age- and sex-matched controls. Portal plasma samples were collected at operation in addition to peripheral venous samples. Immunohistochemical staining for Big ET-1 was performed on a selection of primary tumour specimens and liver metastases.

RESULTS

Median (range) preoperative systemic plasma levels of Big ET-1 were significantly higher in patients with cancer than in controls (1.0 (0.3-9.7) versus 0.2 (0.0-6.0) fmol/ml; P = 0.0001). Intraoperative portal plasma levels of Big ET-1 were significantly higher in patients with Dukes' 'D' disease than in patients with Dukes' A, B and C disease (2.1 (1.4-10.0) versus 1.2 (0.3-6.6) fmol/ml; P = 0. 01). Similarly, systemic plasma levels were significantly higher in patients with Dukes' 'D' disease than in those with localized disease (1.9 (1.2-9.7) versus 1.2 (0.2-8.3) fmol/ml; P = 0.01). The presence of microvascular invasion in the tumour specimens was associated with a significantly raised portal plasma level of Big ET-1 (1.6 (1.5-2.1) versus 1.1 (0.8-1.3) fmol/ml; P = 0.04). Immunohistochemistry localized Big ET-1 to the cancer epithelial cells.

CONCLUSION

The plasma level of Big ET-1 is significantly raised in patients with colorectal cancer. Patients with liver metastases have significantly higher levels than those with localized disease.

Marimastat inhibits neointimal thickening in a model of human arterial intimal hyperplasia

OBJECTIVE

matrix metalloproteases (MMPs) produced by vascular smooth-muscle cells (VSMCs) degrade extracellular matrix and facilitate the migration of these cells. This is a fundamental process in arterial intimal hyperplasia. This study investigated whether Marimastat (a selective but non-specific MMP inhibitor) can prevent intimal hyperplasia in cultured human internal mammary artery (IMA).

MATERIALS AND METHODS

segments of IMA from 8 patients were prepared and cultured for 14 days in serum-supplemented medium (control) or in medium supplemented with Marimastat at 2 concentrations (treatment groups). The tissue was fixed, sectioned, stained and neointimal thicknesses measured by computer-aided image analysis. Further sections were cultured in the same manner and prepared for gel enzymography to quantify the production of MMPs.

RESULTS

neointimal thickness was significantly reduced by Marimastat in a dose-dependent manner when compared to controls (p =0.008 Wilcoxon). Gel enzymography demonstrated a reduction in levels of MMP2 and MMP9. This was most significant for the active forms of the enzymes ( p =0.03).

CONCLUSIONS

our results suggest that there is a potential therapeutic role for specific inhibition of the gelatinases in the prevention of human arterial restenosis.

Production and inhibition of the gelatinolytic matrix metalloproteinases in a human model of vein graft stenosis

OBJECTIVES

human vein graft stenoses are caused by intimal hyperplasia, a process which is characterised by extensive degradation and accumulation of extracellular matrix. This study investigated the role of the matrix metalloproteinases (MMPs) - the principal physiological mediators of extracellular matrix degradation - in the development of intimal hyperplasia in cultured human long saphenous vein.

DESIGN

experimental study.

MATERIALS AND METHODS

paired venous segments with the endothelium intact or denuded were cultured in standard conditions for 14 days. At the termination of culture, MMPs were extracted from one half of the tissue, whilst the remainder of the vein was prepared for histological examination.

RESULTS

stereologic analysis revealed that the endothelium intact veins developed a significantly thicker neointima when compared to the denuded venous segments (20 micron v. 0 micron, p=0.006). Quantification of MMPs by substrate gel enzymography demonstrated that the development of a neointima was associated with increased production of the gelatinolytic MMP-9 (p=0. 03) in intact veins. Immunocytochemistry showed that the MMP-9 localised to the internal elastic lumina, which suggested a role in facilitating smooth-muscle-cell migration into the intima. The role of MMPs-2 and -9 in intimal hyperplasia was further investigated by culturing intact venous segments with a therapeutic concentration of doxycycline--a potent MMP inhibitor. These experiments demonstrated that a therapeutic dose of doxycycline significantly reduced neointimal thickness (control 21 micron, doxycycline 10 mg/l-5.5 micron), in conjunction with a significant reduction in the production of MMP-9.

CONCLUSIONS

these data suggest that elevated levels of MMPs may play a significant role in the development of human intimal hyperplasia and that inhibition of these enzymes may offer a potential therapeutic strategy for the prevention of hyperplastic lesions.

Endothelin-B receptors mediate intimal hyperplasia in an organ culture of human saphenous vein

OBJECTIVE

Although a number of pharmacologic agents have been shown to reduce intimal hyperplasia in animal models of restenosis, to date no systemic agent has conclusively been shown to be effective in humans. Recently, considerable attention has been directed towards endothelin (ET), a potent vasoconstrictor and a powerful mitogen for vascular smooth muscle cells, as a mediator of intimal hyperplasia. Endothelin-1 has been shown to be mitogenic for human saphenous vein smooth muscle cells, and expression also is elevated in human vein graft stenosis. The aim of this study was the investigation of whether ET receptor antagonists can attenuate neointima formation in a laboratory model of vein graft intimal hyperplasia and the determination of whether the effects are mediated by a specific ET receptor subtype.

METHODS

We used an organ culture of human saphenous vein, a well-validated model of vein graft intimal hyperplasia. Paired segments of human long saphenous vein were cultured with and without the following antagonists: bosentan, a nonselective ET receptor antagonist; BQ 123, a specific endothelin-A antagonist; or BQ 788, a specific endothelin-B (ETB) antagonist. After 14 days in the culture, the segments were fixed and processed and the sections were immunostained to facilitate the measurements of neointimal thickness with a computerized image analysis system.

RESULTS

The nonselective antagonist bosentan and the ETB selective antagonist BQ 788 significantly reduced neointima formation by 70% (P = .001) and 50% (P = .03), respectively, but the ETA antagonist BQ 123 had no significant effect on the reduction of neointima formation (P = 1.0).

CONCLUSION

The results of this study imply an important role for ET as a mediator of human vein graft intimal hyperplasia and imply further that a specific ETB antagonist may have a therapeutic potential for the prevention of vein graft stenosis.

Marimastat inhibits neointimal thickening in a model of human vein graft stenosis

BACKGROUND

There is now accumulating evidence that matrix metalloproteinases (MMPs), the physiological mediators of matrix deposition and degradation, play an important role in the development of intimal hyperplasia following arterial bypass. This study investigated the effect of marimastat, an orally active specific MMP inhibitor, on neointima formation in cultured human saphenous vein.

METHODS

Segments of human saphenous vein obtained from ten patients undergoing arterial bypass surgery were cultured for 14 days in serum-supplemented RPMI medium (controls) or in control medium supplemented with marimastat at three different concentrations (treatment groups). Following culture, half of each segment was prepared for histological examination and MMPs were extracted from the other half for gelatin zymography.

RESULTS

Marimastat inhibited neointimal thickening in a concentration-dependent manner; inhibition was significant at 10(-5) and 10(-6) mol/l (P=0.006). This observation was paralleled by a significant reduction in the levels of MMP-2 and MMP-9 in the tissues.

CONCLUSION

Marimastat significantly reduced neointimal thickening in this laboratory model. MMP inhibitors may offer a potential therapeutic strategy in the prevention of intimal hyperplasia.

Endothelin-1 is a mediator of intimal hyperplasia in organ culture of human saphenous vein

BACKGROUND

Endothelin-1 (ET-1) is a powerful vasoconstrictor and a potent mitogen for vascular smooth muscle cells. Excessive smooth muscle cell proliferation is a feature of intimal hyperplasia, the pathological lesion of vein graft stenosis. This study investigates the role of ET-1 in isolated human saphenous vein smooth muscle cells and also in an organ culture of the human saphenous vein.

METHODS

Growth-arrested human saphenous vein smooth muscle cells were stimulated with ET-1 and proliferation quantified by [3H]thymidine uptake in these cells compared with unstimulated control cells. Organ cultures of the human saphenous vein were established with endothelium intact, with endothelium denuded, and with endothelium denuded and the culture medium supplemented with ET-1.

RESULTS

ET-1 stimulated DNA synthesis in isolated smooth muscle cells in a dose-dependent manner with half-maximal stimulation at 1 nmol/l. Addition of ET-1 to denuded vein caused a significant increase in median (range) neointimal thickness, from 4 (0-19) to 20 (4-30) microns (P < 0.05). In veins cultured with ET-1 a parallel increase in median (range) neointimal proliferation index, from 21 (0-31) to 33 (23-46) per cent (P < 0.05), was also observed.

CONCLUSION

These results demonstrate that ET-1 is a mediator of intimal hyperplasia in human saphenous vein in vitro. Endothelin receptor antagonists may therefore be of therapeutic value in the modulation of vein graft intimal hyperplasia.

The development of an in vitro flow model of human saphenous vein graft intimal hyperplasia

OBJECTIVE

Although the role of blood flow has been investigated in animal models of intimal hyperplasia, there have been no detailed studies in intact human vein owing to the difficulties in designing a suitable laboratory model. The aim of this study was to develop a flow model of human vein graft intimal hyperplasia.

METHODS

Organ cultures of human saphenous vein were exposed to laminar flow by culturing in a closed circulatory system under predetermined conditions of venous and arterial shear stress for 14 days. Following fixation and processing, paraffin sections were immunostained and neointimal thicknesses measured.

RESULTS

It was found that arterial flow completely inhibited neointima formation, but venous flow only partly suppressed the response when compared with vein cultured under static conditions. These results are in agreement with previous in vivo studies in a primate graft model, where increased shear stress inhibited intimal proliferation.

CONCLUSION

The endothelial cell is believed to be the key mediator of haemodynamic effects which influence smooth muscle cell proliferation, and the flow rig developed in this study offers the potential to study inter-cellular interactions within the intact vessel. Furthermore, this method provides the facility to study the effects of different flow conditions on segments of vein from the same patient. This model has scope for further development and sophistication which may ultimately lead to increasing our understanding of the aetiology of vein graft stenoses, and hence formulation of preventative strategies.

Human saphenous vein organ culture: a useful model of intimal hyperplasia?

OBJECTIVES

Although cell culture techniques and animal models of intimal hyperplasia have increased our current understanding of the aetiology of vein graft stenosis, the results of such studies have been difficult to relate to the human situation.

DESIGN

The present study was designed to validate an organ culture of human saphenous vein by comparing the changes occurring in cultured vein with those seen in pathological vein graft stenoses and to identify a suitable marker of cell proliferation.

MATERIALS AND METHODS

Saphenous vein segments were cultured for 14 days, fixed in formalin and processed for immunohistochemistry. Freshly excised stenoses were fixed and processed similarly. A number of markers of cell proliferation were evaluated in the culture system in order to identify the one best suited to this particular model.

RESULTS

Marked similarities were observed in the cellular and extracellular matrix composition, and electron microscopy revealed that both the neointima of the cultured vein and the pathological lesion contained an abundance of smooth muscle cells of a secretory phenotype. Bromodeoxyuridine proved to be the most reliable proliferation marker and revealed that early proliferation in the superficial layers of the vein intima gave rise to the formation of neointima. Both proliferation and neointimal thickness were maximal by day 14 in culture. Proliferation declined rapidly thereafter, and the neointima was maintained.

CONCLUSIONS

The changes occurring in cultured vein and graft stenoses bore many similarities, thereby justifying the use of organ culture as a valuable experimental tool.

Renal and spermatozoal toxicity of alpha-bromohydrin, 3-bromolactate and 3-bromopyruvate

(R,S)- and (R)-3-Bromopropan-1,2-diol (alpha-bromohydrin) produced diuresis and glucosuria when administered to male rats but had no effect on the metabolic activity of rat kidney tubules in vitro. The oxidation products (R,S)-3-bromolactate and 3-bromopyruvate produced brief phases of diuresis but not glucosuria, and severely inhibited the metabolic activity of rat kidney tubules in vitro. alpha-Bromohydrin had no effect on the metabolic activity of boar spermatozoa whereas the oxidation products severely affected mitochondrial metabolism. 3-Bromopyruvate also inhibited boar spermatozoal glyceraldehyde 3-phosphate dehydrogenase.

Osteopontin is not a marker for proliferating human vascular smooth muscle cells

Osteopontin (OP) is a secreted glycoprotein that contains the Arg-Gly-Asp (RGD) cell-binding sequence that binds calcium and is chemotactic and adhesive for rat vascular smooth muscle cells (VSMCs). OP gene expression is upregulated in cultured rat VSMCs in vitro and after balloon carotid injury in vivo, suggesting that OP may be a marker for proliferating VSMCs in vivo and in vitro. Our in situ hybridization studies of human atherosclerotic coronary vessels, however, have shown OP mRNA expression in plaque macrophages but not VSMCs. The current study investigated OP mRNA expression in cultured human VSMCs and macrophages and in an organ culture model of neointima formation in human saphenous vein. OP mRNA expression was not detected by Northern blot analysis of total RNA from subconfluent or confluent cultures of human VSMCs of any passage maintained in normal growth medium or after stimulation with TGF beta 1 (20 ng/mL), angiotensin II (1 mumol/L), or basic fibroblast growth factor (10 mg/mL) but was just detectable after stimulation with activation vitamin D3 (1 mumol/L). In contrast, cultured human macrophages expressed high levels of OP mRNA that were not dependent on lipid loading. OP mRNA was detected in isolated foci in all layers of saphenous veins maintained in organ culture for 14 days, including <2% of neointimal cells, a distribution that paralleled that of tissue macrophages. These results suggest that OP gene expression is not a marker for proliferation of human VSMCs in vitro and highlight a fundamental difference in the biology of human and rodent VSMCs.

Is the nephrotoxicity of (R)-3-chlorolactate in the rat caused by 3-chloropyruvate?

1. When (R, S)-[3-36 Cl]chlorolactate was administered to male rats, two radioactive constituents were excreted in the urine. These were identified as 36Cl- and [3-36 Cl]chlorolactate which was subsequently shown to be essentially the (S)-isomer. 2. Analysis of the urinary oxalate content from rats receiving either (R)- or (S)-3-chlorolactate revealed that elevated levels were produced by the (R)-isomer whereas normal levels followed the administration of the (S)-isomer. 3. Treatment of (R,S)-3-chlorolactate with a modified Fenton's oxidizing system produced oxalate and an intermediate which was identified as 3-chloropyruvate. 4. 3-Chloropyruvate is a potent nephrotoxin in the rat producing a brief phase of diuresis when administered, increasing the urinary excretion of oxalate and inhibiting the oxidative metabolic capability of rat kidney tubules and rat kidney mitochondria in vitro. 5. Both (R)-3-chlorolactate and 3-chloropyruvate were shown to be inhibitors of the commercially-available pyruvate dehydrogenase complex. 6. 3-Chloropyruvate inhibits kidney mitochondrial metabolism possibly at the pyruvate dehydrogenase complex level and appears to be a metabolite of (R)- but not (S)-3-chlorolactate.