Marked differences in local bone remodelling in response to different marrow stimulation techniques in a large animal.

Marrow stimulation, including subchondral drilling and microfracture, is the most commonly performed cartilage repair strategy, whereby the subchondral bone plate is perforated to release marrow-derived cells into a cartilage defect to initiate repair. Novel scaffolds and therapeutics are being designed to enhance and extend the positive short-term outcomes of this marrow stimulation. However, the translation of these newer treatments is hindered by bony abnormalities, including bone resorption, intralesional osteophytes, and bone cysts, that can arise after marrow stimulation. In this study, three different marrow stimulation approaches - microfracture, subchondral drilling and needle-puncture - were evaluated in a translationally relevant large-animal model, the Yucatan minipig. The objective of the study was to determine which method of marrow access (malleted awl, drilled Kirschner wire or spring-loaded needle) best preserved the underlying subchondral bone. Fluorochrome labels were injected at the time of surgery and 2 weeks post-surgery to capture bone remodelling over the first 4 weeks. Comprehensive outcome measures included cartilage indentation testing, histological grading, microcomputed tomography and fluorochrome imaging. Findings indicated that needle-puncture devices best preserved the underlying subchondral bone relative to other marrow access approaches. This may relate to the degree of bony compaction occurring with marrow access, as the Kirschner wire approach, which consolidated bone the most, induced the most significant bone damage with marrow stimulation. This study provided basic scientific evidence in support of updated marrow stimulation techniques for preclinical and clinical practice.

Are adult carpal angle measurements applicable to the pediatric population in the trauma setting?

OBJECTIVE: The aim of this study is to assess the applicability of standard adult carpal angle measurements, specifically the scapholunate and capitolunate angles, in the assessment of the pediatric wrist. MATERIALS AND METHODS: The study cohort comprised male and female children who underwent a wrist radiograph for the evaluation of suspected wrist injuries following trauma. A gender- and indication-matched adult cohort was also assessed. To ensure an accurate carpal angle measurement, only individuals with a sufficiently ossified carpus and an adequately positioned lateral wrist radiograph were included. RESULTS: Carpal angle measurements were performed on the lateral wrist radiographs of 256 individuals between the ages of 5 and 17 years (mean 11.2 years, SD ± 2.5 years) and 256 individuals between the ages of 18 and 40 years (mean 28.8 years, SD ± 6.2 years). The mean pediatric scapholunate angle was 47° (SD ± 8) and the mean pediatric capitolunate angle was 11° (SD ± 7). The mean adult scapholunate and capitolunate angles were 48° (SD ± 8°) and 10° (SD ± 6°) respectively. No statistically significant difference was observed between the scapholunate or capitolunate angle measurements in the two groups (p = 0.26 and p = 0.36). CONCLUSION: The study data supports the applicability of standard adult carpal angle values to the pediatric population provided the carpus is sufficiently ossified.

The differences between sex offenders who victimise older women and sex offenders who offend against children.

OBJECTIVES: Within the literature on sex offending, much attention is paid to the distinction between those sex offenders who offend against adults and those who offend against children. In contrast, there is a paucity of research into sex offenders who offend specifically against elderly or older victims. METHOD: A detailed interview and psychometric tests were conducted with a sample of 28 sex offenders who had been convicted of a sexually motivated offence against an older female. These data were compared to a sample of 23 child sex offenders. RESULTS: Results indicate that amongst other significant differences between these sub-groups, men who offend against older women are generally younger, are more violent, and are more likely to use a weapon and cause injury and death compared to child sex offenders. The men who offended against children were more likely to think about and plan their offending, spend more time with the victim pre and post offence, admit sexual arousal during the offence, and admit to a sexual motivation for the offence. CONCLUSIONS: This study suggests that men who sexually offend against older women and men who sexually offend against children are distinct groups. Treatment and risk management strategies should take this into account. Further exploration of this sub-group of offenders is recommended to help inform treatment and risk management strategies for sex offenders who offend against older people.

Chronic Disease Management - The Patient's Perspective.

A paucity of data exists on Irish patients' perspective of chronic disease management. This study explores patients' views on what is the most appropriate setting for their chronic disease management, the advantages and disadvantages of these settings, and where they get information on their condition. Semi-structured qualitative interviews were carried out with 24 patients. Three main themes emerged: Current Care Model, Health Literacy and Treatment Burden. Patients believe that the GP-patient relationship plays a pivotal role in the provision of chronic disease management. Health literacy and psychosocial burden were found to impact significantly on the lives of patients with chronic disease(s).

Proliferative Capacity and Phenotypical Alteration of Multipotent Ecto-Mesenchymal Stem Cells from Human Exfoliated Deciduous Teeth Cultured in Xenogeneic and Allogeneic Media.

Foetal calf serum (FCS) is a standard supplement used in media for in vitro stem cell cultivation. This xenogeneic supplement remains widely used for its favourable growth-promoting properties and ease of accessibility; however, it is inherently not fit for human medicine due to its capacity to temper with the cultured cell quality. For this reason, the international community encourages research and development of allogeneic sera, which would expunge this issue. This study aims to investigate the differences in proliferative capacity, phenotype, and differentiation capacity of ecto-mesenchymal stem cells from human exfoliated deciduous teeth (SHED) cultured in vitro in media supplemented with allogeneic and xenogeneic sera. To address these aims, we cultured three lineages of stem cells in media supplemented with FCS in a concentration of 2% + growth factors; human blood plasma and platelet-rich plasma in concentrations of 2% + growth factors, and 10%. Here, the xenogeneic cultivation was considered as a basis for comparison because this serum is commonly used in studies concerning ecto-mesenchymal stem cells. The study shows that multipotent ecto-mesenchymal SHED can be feasibly cultivated in media where the xenogeneic FCS is substituted by allogeneic platelet-rich plasma, considering the cultured cell proliferative and differentiation capacities. We have also proved that different sera impact the cultured cells' phenotype differently, which has major implications for previous and future stem cell research and regenerative therapy.

An unequivocal good? Acknowledging the complexities of advance care planning.

Over the past few decades advance care planning (ACP) has become the subject of debate, research and legislation in many countries. Encouraging people to express their preference for treatment in advance, ideally in written form, seems a natural way to identify what someone might have wanted when they can no longer participate in decision-making. The notion of ACP as an unequivocal good permeates much of the research and policy work in this area. For example, ACP is now actively encouraged in Australian federal and state government policies and the Victorian Government has recently published a practical ACP strategy for Victorian health services (2014-2018). However, advance care plan is ethically complex and the introduction of the Victorian health services strategy provides an opportunity to reflect on this complexity, particularly on the benefits and risks of ACP.

Clinical observed performance evaluation: a prospective study in final year students of surgery.

We report a prospective study of clinical observed performance evaluation (COPE) for 197 medical students in the pre-qualification year of clinical education. Psychometric quality was the main endpoint. Students were assessed in groups of 5 in 40-min patient encounters, with each student the focus of evaluation for 8 min. Each student had a series of assessments in a 25-week teaching programme. Over time, several clinicians from a pool of 16 surgical consultants and registrars evaluated each student by direct observation. A structured rating form was used for assessment data. Variance component analysis (VCA), internal consistency and inter-rater agreement were used to estimate reliability. The predictive and convergent validity of COPE in relation to summative OSCE, long case, and overall final examination was estimated. Median number of COPE assessments per student was 7. Generalisability of a mean score over 7 COPE assessments was 0.66, equal to that of an 8 × 7.5 min station final OSCE. Internal consistency was 0.88-0.97 and inter-rater agreement 0.82. Significant correlations were observed with OSCE performance (R = 0.55 disattenuated) and long case (R = 0.47 disattenuated). Convergent validity was 0.81 by VCA. Overall final examination performance was linearly related to mean COPE score with standard error 3.7%. COPE permitted efficient serial assessment of a large cohort of final year students in a real world setting. Its psychometric quality compared well with conventional assessments and with other direct observation instruments as reported in the literature. Effect on learning, and translation to clinical care, are directions for future research.

Male circumcision for HIV prevention in Papua New Guinea: a summary of research evidence and recommendations for public health following a national policy forum.

In 2005, a clinical trial in South Africa found that circumcision of young men could reduce their risk of acquiring HIV (human immunodeficiency virus) infection by over 60%. In the following year, two more trials in Africa confirmed this finding, leading the World Health Organization to recommend male circumcision as a public health strategy for HIV prevention in high-incidence countries. In order to inform public health policy in Papua New Guinea (PNG), two major research projects were initiated with the goals of investigating the status of penile cutting practices and assessing understandings, acceptability, feasibility and cost-effectiveness of male circumcision for HIV prevention. In addition, behavioural surveillance surveys systematically asked questions on penile cutting practices and an ethnographic literature review informed historical perspectives of penile cutting in PNG. Key findings from these research activities were presented at a National Policy Forum on Male Circumcision for HIV Prevention held in Port Moresby in November 2011. The Forum made three key recommendations: (1) the formation of a joint National Department of HealthlNational AIDS Council Secretariat Policy Committee on male circumcision; (2) the establishment of an integrated harm reduction program; and (3) that future policy on wide-scale roll-out of male circumcision for HIV prevention in PNG be informed by a combination of data from (a) male circumcision intervention pilot programs and (b) research on the potential protective effect of other forms of penile cutting.

An exploration of the impact of ethanol diluent on breath alcohol concentration in patients receiving paclitaxel chemotherapy.

PURPOSE: This study aimed to provide a better understanding of the impact of paclitaxel chemotherapy on breath alcohol in an Irish population. METHODS: Patients attending the Oncology Day Unit at Beaumont Hospital were invited to participate on the day of their treatment. The brand of paclitaxel used was Actavis Pharma Inc and contained 6 mg/mL paclitaxel in 50% Ethanol/ 50% Cremophor EL. Breath alcohol concentration was measured using the AlcoSense ™ Breathalyser on three separate visits. The primary end-point was the number of patients who were above the legal threshold for drink driving in Ireland. RESULTS: In total, 50 patients were recruited. 36 (68%) were female. The most common diagnosis was breast cancer (56%). Ten (20%) patients had metastatic disease and 4 (8%) had liver metastases. The mean paclitaxel dose administered was 118 mg. The mean amount of ethanol infused was 7.7 g. 27 patients had a detectable breath alcohol level on at least one visit. The mean breath alcohol concentration was 2 mcg/100 mL or 0.02 mg/L of breath. The maximum concentration of ethanol in exhaled breath was 11 mcg/100 mL or 0.11 mg/L which is 50% of the statutory limit for drink driving in Ireland. A weak correlation was observed between ethanol concentration in exhaled breath and the total amount of ethanol administered. Although no patient exceeded the general limit for drink driving in Ireland, three (6%) participants had a breath alcohol concentration above the threshold for professional, learner or novice drivers. CONCLUSION: Although definitive conclusions are limited by relatively small numbers, it seems unlikely that weekly paclitaxel infusions pose any significant risk to patients driving.

Granzyme B (GraB) autonomously crosses the cell membrane and perforin initiates apoptosis and GraB nuclear localization.

Granzyme B (GraB) induces apoptosis in the presence of perforin. Perforin polymerizes in the cell membrane to form a nonspecific ion pore, but it is not known where GraB acts to initiate the events that ultimately lead to apoptosis. It has been hypothesized that GraB enters the target cell through a perforin channel and then initiates apoptosis by cleaving and activating members of the ICE/Ced-3 family of cell death proteases. To determine if GraB can enter the cell, we treated YAC-1 or HeLa cells with FITC-labeled GraB and measured intracellular fluorescence with a high sensitivity CCD camera and image analyzer. GraB was internalized and found diffusely dispersed in the cell cytoplasm within 10 min. Uptake was inhibited at low temperature (4 degrees C) and by pretreatment with metabolic inhibitors, NaF and DNP, or cytochalasin B, a drug that both blocks microfilament formation, and FITC-GraB remained on the cell membrane localized in patches. With the simultaneous addition of perforin and FITC-GraB, no significant increase in cytoplasmic fluorescence was observed over that found in cells treated only with FITC-GraB. However, FITC-GraB was now detected in the nucleus of apoptotic cells labeling apoptotic bodies and localized areas within and along the nuclear membrane. The ability of GraB to enter cells in the absence of perforin was reexamined using anti-GraB antibody immunogold staining of ultrathin cryosections of cells incubated with GraB. Within 15 min, gold particles were detected both on the plasma membrane and in the cytoplasm of cells with some gold staining adjacent to the nuclear envelope but not in the nucleus. Cells internalizing GraB in the absence of perforin appeared morphologically normal by Hoechst staining and electron microscopy. GraB directly microinjected into the cytoplasm of B16 melanoma cells induced transient plasma membrane blebbing and nuclear coarsening but the cells did not become frankly apoptotic unless perforin was added. We conclude that GraB can enter cells autonomously but that perforin initiates the apoptotic process and the entry of GraB into the nucleus.

Initiation of apoptosis by granzyme B requires direct cleavage of bid, but not direct granzyme B-mediated caspase activation.

The essential upstream steps in granzyme B-mediated apoptosis remain undefined. Herein, we show that granzyme B triggers the mitochondrial apoptotic pathway through direct cleavage of Bid; however, cleavage of procaspases was stalled when mitochondrial disruption was blocked by Bcl-2. The sensitivity of granzyme B-resistant Bcl-2-overexpressing FDC-P1 cells was restored by coexpression of wild-type Bid, or Bid with a mutation of its caspase-8 cleavage site, and both types of Bid were cleaved. However, Bid with a mutated granzyme B cleavage site remained intact and did not restore apoptosis. Bid with a mutation preventing its interaction with Bcl-2 was cleaved but also failed to restore apoptosis. Rapid Bid cleavage by granzyme B (<2 min) was not delayed by Bcl-2 overexpression. These results clearly placed Bid cleavage upstream of mitochondrial Bcl-2. In granzyme B-treated Jurkat cells, endogenous Bid cleavage and loss of mitochondrial membrane depolarization occurred despite caspase inactivation with z-Val-Ala-Asp-fluoromethylketone or Asp-Glu-Val-Asp-fluoromethylketone. Initial partial processing of procaspase-3 and -8 was observed irrespective of Bcl-2 overexpression; however, later processing was completely abolished by Bcl-2. Overall, our results indicate that mitochondrial perturbation by Bid is necessary to achieve a lethal threshold of caspase activity and cell death due to granzyme B.

Motivation for participating in phase 1 vaccine trials: Comparison of an influenza and an Ebola randomized controlled trial.

INTRODUCTION/HYPOTHESIS: Recruitment of participants into phase 1 vaccine clinical trials can be challenging since these vaccines have not been used in humans and there is no perceived benefit to the participant. Occasionally, as was the case with a phase 1 clinical trial of an Ebola vaccine in Halifax, Canada, during the 2014-2016 West African Ebola virus outbreak, recruitment is less difficult. In this study, we explored the motivations of participants in two phase 1 vaccine trials that were concurrently enrolling at the same centre and compared the motivations of participants in a high-profile phase 1 Ebola vaccine trial to those in a less high-profile phase 1 adjuvanted seasonal influenza vaccine study. METHODS: An online survey which included participants' prior experience with clinical trials, motivations to participate (including financial incentives), and demographic information was developed to examine the motivations of healthy participants in two phase 1 clinical vaccine trials conducted at the Canadian Center for Vaccinology in Halifax, Nova Scotia. Participants were invited via email to complete the online survey. Readability and clarity were assessed through pilot testing. RESULTS: A total of 49 (55.7%) of 88 participants of the two studies completed the survey (22 [55%] of 40 participants from the Ebola vaccine study and 27 [56.3%] of 48 from the adjuvanted influenza vaccine study). Motivations that were most frequently ranked among participants' top three in both trials were (1) wanting to contribute to the health of others, (2) wanting to participate in something important, (3) wanting to contribute to the advancement of science, and (4) wanting to receive an incentive such as money or a tablet. CONCLUSIONS/RECOMMENDATIONS: Although media attention and financial compensation were more often cited by Ebola vaccine trial participants as a reason to participate, both altruistic and self-interested factors were important motivations for participants in their decision to participate in a phase 1 vaccine clinical trial.

Mechanisms of hypochlorite injury of target cells.

HOCl, which is produced by the action of myeloperoxidase during the respiratory burst of stimulated neutrophils, was used as a cytotoxic reagent in P388D1 cells. Low concentrations of HOCl (10-20 microM) caused oxidation of plasma membrane sulfhydryls determined as decreased binding of iodoacetylated phycoerythrin. These same low concentrations of HOCl caused disturbance of various plasma membrane functions: they inactivated glucose and aminoisobutyric acid uptake, caused loss of cellular K+, and an increase in cell volume. It is likely that these changes were the consequence of plasma membrane SH-oxidation, since similar effects were observed with para-chloromercuriphenylsulfonate (pCMBS), a sulfhydryl reagent acting at the cell surface. Given in combination pCMBS and HOCl showed an additive effect. Higher doses of HOCl (greater than 50 microM) led to general oxidation of -SH, methionine and tryptophan residues, and formation of protein carbonyls. HOCl-induced loss of ATP and undegraded NAD was closely followed by cell lysis. In contrast, NAD degradation and ATP depletion caused by H2O2 preceded cell death by several hours. Formation of DNA strand breaks, a major factor of H2O2-induced injury, was not observed with HOCl. Thus targets of HOCl were distinct from those of H2O2 with the exception of glyceraldehyde-3-phosphate dehydrogenase, which was inactivated by both oxidants.

Cytosolic delivery of granzyme B by bacterial toxins: evidence that endosomal disruption, in addition to transmembrane pore formation, is an important function of perforin.

Granule-mediated cell killing by cytotoxic lymphocytes requires the combined actions of a membranolytic protein, perforin, and granule-associated granzymes, but the mechanism by which they jointly kill cells is poorly understood. We have tested a series of membrane-disruptive agents including bacterial pore-forming toxins and hemolytic complement for their ability to replace perforin in facilitating granzyme B-mediated cell death. As with perforin, low concentrations of streptolysin O and pneumolysin (causing <10% (51)Cr release) permitted granzyme B-dependent apoptosis of Jurkat and Yac-1 cells, but staphylococcal alpha-toxin and complement were ineffective, regardless of concentration. The ensuing nuclear apoptotic damage was caspase dependent and included cleavage of poly(ADP-ribose) polymerase, suggesting a mode of action similar to that of perforin. The plasma membrane lesions formed at low dose by perforin, pneumolysin, and streptolysin did not permit diffusion of fluorescein-labeled proteins as small as 8 kDa into the cell, indicating that large membrane defects are not necessary for granzymes (32 to 65 kDa) to enter the cytosol and induce apoptosis. The endosomolytic toxin, listeriolysin O, also effected granzyme B-mediated cell death at concentrations which produced no appreciable cell membrane damage. Cells pretreated with inhibitors of endosomal trafficking such as brefeldin A took up granzyme B normally but demonstrated seriously impaired nuclear targeting of granzyme B when perforin was also added, indicating that an important role of perforin is to disrupt vesicular protein trafficking. Surprisingly, cells exposed to granzyme B with perforin concentrations that produced nearly maximal (51)Cr release (1,600 U/ml) also underwent apoptosis despite excluding a 8-kDa fluorescein-labeled protein marker. Only at concentrations of >4,000 U/ml were perforin pores demonstrably large enough to account for transmembrane diffusion of granzyme B. We conclude that pore formation may allow granzyme B direct cytosolic access only when perforin is delivered at very high concentrations, while perforin's ability to disrupt endosomal trafficking may be crucial when it is present at lower concentrations or in killing cells that efficiently repair perforin pores.

A Cu(ii) complex targeting the translocator protein: in vitro and in vivo antitumor potential and mechanistic insights.

A new Cu-based anticancer metallodrug which targets the translocator protein is reported. [CuBr2(TZ6)] elicits a remarkable in vitro cytotoxicity in sensitive and multidrug resistant cell lines and induces a 98% reduction of tumor mass in a murine tumor model. Target binding was studied by experimental and computational methods.

Intracardiac recording by catheter electrode of accessory pathway depolarization.

At electrophysiologic study in a patient with the Wolff-Parkinson-White syndrome, intracardiac catheter recordings demonstrated a deflection that occurred 30 ms before ventricular activation. The rapid deflection was present during ventricular preexcitation but not during normal atrioventricular conduction. All QRS complexes were preexcited to varying degrees during atrial fibrillation, yet the deflection consistently preceded ventricular activation by 30 ms. This deflection most likely represents the rare recording of a Kent bundle depolarization with an intracardiac electrode catheter.

Electrophysiologic effects and clinical efficacy of oral propafenone therapy in patients with ventricular tachycardia.

The effects of the antiarrhythmic agent propafenone were evaluated in 25 patients with recurrent symptomatic ventricular tachycardia. Oral propafenone was given to a maximal dose of 300 mg every 8 hours. Ten of the 25 patients developed side effects or had inadequate suppression of spontaneous ventricular arrhythmias during propafenone therapy. Electrophysiologic studies were performed before and during drug therapy on the 15 patients who had a satisfactory clinical response. Propafenone increased the PR interval from 168 +/- 46 to 188 +/- 25 ms (p less than 0.007), the HV interval from 47 +/- 10 to 65 +/- 13 ms (p less than 0.005), the shortest atrial pacing cycle length to maintain 1:1 atrioventricular (AV) nodal conduction from 385 +/- 44 to 436 +/- 42 ms (p less than 0.005), the ventricular effective refractory period from 231 +/- 17 to 255 +/- 19 ms (p less than 0.001) and the ventricular functional refractory period from 260 +/- 15 to 278 +/- 17 ms (p less than 0.002). Before propafenone therapy, all 15 patients had ventricular tachycardia induced by programmed ventricular stimulation. During propafenone treatment, 12 patients still had ventricular tachycardia induced, and the tachycardia cycle length significantly increased from 236 +/- 44 to 374 +/- 103 ms (p less than 0.001). Ten patients were considered to have satisfactory electrophysiologic response to propafenone on the basis of either the inability to initiate ventricular tachycardia or a marked increase in ventricular tachycardia cycle length associated with lack of symptoms during the induced tachycardia. These patients were discharged receiving propafenone.(ABSTRACT TRUNCATED AT 250 WORDS)

Initial experience with reuse of coronary angioplasty catheters in the United States.

OBJECTIVES: We sought to evaluate the performance of angioplasty catheters, restored under a strict manufacturing process, in patients with coronary artery disease. BACKGROUND: Most countries outside the United States routinely reuse disposable medical equipment, resulting in significant cost savings. Because of quality and legal concerns, reuse in the United States has been limited. We investigated the reuse of percutaneous transluminal coronary angioplasty (PTCA) balloon catheters, restored by a process strictly controlled for bioburden and sterility, in patients undergoing PTCA. METHODS: Used PTCA balloon catheters were shipped to a central facility and were decontaminated, cleaned and tested for endotoxin using the limulus amebocyte lystate (LAL) gel clot method. Physical testing and quality assurance were performed. The products were packaged and sterilized with ethylene oxide. Catheter performance was assessed in a pilot study powered to detect a 5% difference in the angiographic failure rates of new and reused balloons (beta 0.8). RESULTS: The study enrolled 107 patients. The indication for PTCA was stable angina pectoris in 69 patients, unstable angina in 22 and acute myocardial infarction in 16. Of the 107 patients enrolled, 106 had a successful laboratory outcome, and 1 required coronary artery bypass graft surgery after failed rescue stenting. There were 122 lesions attempted (American College of Cardiology/American Heart Association classification A, n = 32; B1, n = 43; > or = B2, n = 35; C, n = 12). Of the 110 lesions initially approached with restored PTCA catheters, 108 were crossed and dilated. Sixty-four required no further procedures. Stenting was performed in 37 patients (29 planned, 8 rescue). Thus, the angiographic failure rate was 7% (10 of 108, 95% confidence interval 2% to 12%), comparable to the 10% rate seen with new balloons in other studies. CONCLUSIONS: Restoration of disposable coronary angioplasty catheters using a highly controlled process appears to be safe and effective, with success rates similar to those of new products and no detectable sacrifice in performance. Cost analysis suggests that implementation of reuse technology for expensive disposable equipment may offer cost savings for U.S. hospitals, without sacrifice of quality.

Clinical efficacy and electrophysiologic effects of cibenzoline therapy in patients with ventricular arrhythmias.

Cibenzoline, a new antiarrhythmic agent, was tested in 26 patients who had symptomatic ventricular tachycardia (24 patients) or premature ventricular complexes (2 patients) unresponsive to conventional drugs. Cibenzoline was given orally every 8 hours to maximal doses of 65 mg in 2 patients, 81.25 mg in 22 patients and 97.5 mg in 2 patients. Cibenzoline abolished spontaneous episodes of ventricular tachycardia in 8 of 16 patients with ventricular tachycardia during a 72 hour control electrocardiographic recording, and 7 of 22 patients had greater than 83% decrease in premature ventricular complexes compared with control. The PR interval increased 14% (p less than 0.001), QRS duration increased 17% (p less than 0.001), QT interval did not change and mean ejection fraction in 10 patients did not change. Electrophysiologic studies were performed on 10 patients in the control period and during maximal cibenzoline dosage. Cibenzoline did not affect electrophysiologic properties of the atrium or atrioventricular (AV) node. It prolonged the ventricular effective (223 +/- 16 to 241 +/- 22 ms, p less than 0.02) and functional (247 +/- 18 to 264 +/- 25 ms, p less than 0.02) refractory periods. At control electrophysiologic studies, ventricular tachycardia was induced in 9 of 10 patients (mean cycle length 210 +/- 31 ms). Cibenzoline therapy prevented ventricular tachycardia induction in two patients, and in the other seven patients the mean ventricular tachycardia cycle length increased from 210 to 260 ms. The one patient with no ventricular arrhythmia induced during the control study still had no arrhythmia induced while receiving cibenzoline.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of external beam irradiation on neointimal hyperplasia after experimental coronary artery injury.

Human coronary artery restenosis after percutaneous revascularization is a response to mechanical injury. Smooth muscle cell proliferation is a major component of restenosis, resulting in obstructive neointimal hyperplasia. Because ionizing radiation inhibits cellular proliferation, this study tested in a porcine coronary injury model the hypothesis that the hyperplastic response to coronary artery injury would be attenuated by X-irradiation. Deep arterial injury was produced in 37 porcine left anterior descending coronary artery segments with overexpanded, percutaneously delivered tantalum wire coils. Three groups of pigs were irradiated with 300-kV X-rays after coil injury: Group I (n = 10), 400 cGy at 1 day; Group II (n = 10), 400 cGy at 1 day and 400 cGy at 4 days and Group III (n = 9), 800 cGy at 1 day. Eight pigs in the control group underwent identical injury but received no radiation. Treatment efficacy was histologically assessed by measuring neointimal thickness and percent area stenosis. Mean neointimal thickness in all irradiated groups was significantly higher than in the control groups and thickness was proportional to X-ray dose. X-irradiation delivered at these doses and times did not inhibit proliferative neointima. Rather, it accentuated the neointimal response to acute arterial injury and may have potentiated that injury.