Towards an understanding of the nature of resistance to Phytophthora root rot in red raspberry

A mapping population segregating for root rot resistance was screened under both field and glasshouse conditions over a number of seasons. Few correlations between field and glasshouse scores were significant. Final root rot scores were significantly negatively correlated with measures of root vigour. Two QTL associated with resistance were identified as were overlapping QTL for root vigour assessments. Markers significantly associated with the traits were used to identify BAC clones, which were subsequently sequenced to examine gene content. A number of genes were identified including those associated with stem cell identity, cell proliferation and elongation in the root zone, control of meristematic activity and organisation, cell signalling, stress response, sugar sensing and control of gene expression as well as a range of transcription factors including those known to be associated with defence. For marker-assisted breeding, the SSR marker Rub118b 110 bp allele from Latham was found in resistant germplasm but was not found in any of the susceptible germplasm tested.

Temporal trends in diabetes prevalence and key diabetes risk factors in Scotland, 2003-2008

AIMS

We assessed temporal trends in diabetes prevalence and key diabetes risk factors (obesity, physical activity, smoking) over 5 years in a nationally representative sample.

METHODS

Participants were drawn from the Scottish Health Surveys, which recruited two separate, nationally representative samples in 2003 (n = 7229, aged 50.5 ± 17.2 years) and 2008 (n = 6313, aged 51.8 ± 17.6 years). Prevalent diabetes was assessed from a self-reported physician's diagnosis, and high diabetes risk or undiagnosed cases were defined from HbA(1c) ≥ 6.0% (≥ 42 mmol/mol) to < 6.5% (< 47.5 mmol/mol) and ≥ 6.5% (≥ 47.5 mmol/mol), respectively.

RESULTS

Over 5 years there was an increased prevalence of diabetes (5.2 vs. 9.4% in 2003 and 2008, respectively) and in the prevalence of high diabetes risk (2.9 vs. 12.4%). These differences were accentuated in participants aged 65 years and above; for diabetes, there was a prevalence of 12 and 17.3% in 2003 and 2008, respectively, and, for high risk, the prevalence was 7.8 and 24.7%, respectively. There was also an increase in diabetes risk factors, including obesity and lack of physical activity, although these factors did not explain the diabetes trend.

CONCLUSIONS

These results suggest nearly a doubling in the prevalence of diabetes over 5 years in Scotland.

Low dose (0.05 units/kg/h) is comparable with standard dose (0.1 units/kg/h) intravenous insulin infusion for the initial treatment of diabetic ketoacidosis in children with type 1 diabetes-an observational study

OBJECTIVE

To compare low dose (0.05 units/kg/h) with standard dose (0.1 units/kg/h) intravenous insulin infusion for the treatment of diabetic ketoacidosis (DKA) in children with type 1 diabetes.

STUDY DESIGN

Data from five paediatric centres were compared in children who received 0.05 (41 episodes) or 0.1 units/kg/h (52 episodes).

RESULTS

In the low vs. standard dose group, at 6 h following admission, the fall in blood glucose levels [11.3 (95% confidence interval 8.6 to 13.9) vs. 11.8 (8.4 to 15.2) mmol/L, p = 0.86] and rise in pH [0.13 (0.09 to 0.18) vs. 0.11 (0.07 to 0.15), p = 0.78] were similar. These changes were comparable between doses in relation to: severity of initial acidosis, children newly diagnosed with diabetes or aged less than 5 years. After adjustment for other clinical and biochemical covariates, insulin dose was unrelated to the change in pH and blood glucose levels at 6 h following admission. Comparisons of safety data, particularly in relation to abnormal Glasgow Coma Score, were inconclusive.

CONCLUSION

In this observational study, low dose was as effective as standard dose intravenous insulin infusion in the initial treatment (less than 6 h) of DKA in children with type 1 diabetes. A randomised controlled trial is required to show true equivalence between doses and to evaluate potential safety benefits.

A randomised controlled trial to compare minimally invasive glucose monitoring devices with conventional monitoring in the management of insulin-treated diabetes mellitus (MITRE)

OBJECTIVES

To evaluate whether the additional information provided by minimally invasive glucose monitors results in improved glycaemic control in people with poorly controlled insulin-requiring diabetes, and to assess the acceptability and health economic impact of the devices.

DESIGN

A four-arm randomised controlled trial was undertaken.

SETTING

Participants were recruited from secondary care diabetes clinics in four hospitals in England.

PARTICIPANTS

404 people aged over 18 years with insulin-treated diabetes mellitus (types 1 or 2) for at least 6 months who were receiving two or more injections of insulin daily were eligible. Participants had to have had two glycosylated haemoglobin (HbA1c) values > or = 7.5% in the last 15 months.

INTERVENTIONS

Participants were randomised to one of four groups. Two groups received minimally invasive glucose monitoring devices [GlucoWatch Biographer or MiniMed Continuous Glucose Monitoring System (CGMS)]. These groups were compared with an attention control group (standard treatment with nurse feedback sessions at the same frequency as those in the device groups) and a standard control group (reflecting common practice in the clinical management of diabetes in the UK).

MAIN OUTCOME MEASURES

Change in HbA1c from baseline to 3, 6, 12 and 18 months was the primary indicator of short- to long-term efficacy in this study. Perceived acceptability of the devices was assessed by use and a self-report questionnaire. A health economic analysis was also performed.

RESULTS

At 18 months all groups demonstrated a decline in HbA1c levels from baseline. Mean percentage changes in HbA1c were -1.4 for the GlucoWatch group, -4.2 for the CGMS group, -5.1 for the attention control group and -4.9 for the standard care control group. At 18 months the relative percentage reduction in HbA1c in each of the intervention arms was less than that in the standard care control group. In the intention to treat analysis no significant differences were found between any of the groups at any of the assessment times. There was no evidence that the additional information provided by the devices resulted in any change in the number or nature of treatment recommendations offered by the nurses. The health economics analysis indicated no advantage in the groups who received the devices; a lower cost and higher benefit were found for the attention control arm. Assessment of device use and acceptability indicated a decline in use of both devices, which was most marked in the GlucoWatch group by 18 months (20% still using GlucoWatch versus 57% still using the CGMS). The GlucoWatch group reported more side effects, greater interference with daily activities and more difficulty in using the device than the CGMS group.

CONCLUSIONS

Continuous glucose monitors do not lead to improved clinical outcomes and are not cost-effective for improving HbA1c in unselected individuals with poorly controlled insulin-requiring diabetes. On acceptability grounds the data suggest that the GlucoWatch will not be frequently used by individuals with diabetes because of the large number of side effects.

Randomized controlled trial to assess the impact of continuous glucose monitoring on HbA(1c) in insulin-treated diabetes (MITRE Study)

AIMS

To determine whether continuous glucose information provided through use of either the GlucoWatch G2 Biographer or the MiniMed continuous glucose monitoring system (CGMS) results in improved glycated haemoglobin (HbA(1c)) for insulin-treated adults with diabetes mellitus, relative to an attention control and standard care group.

METHODS

Four hundred and four adults taking at least two daily insulin injections and with two consecutive HbA(1c) values > or = 7.5% were recruited to this randomized controlled trial (RCT). All were trained at baseline to use the same monitor for traditional capillary glucose testing throughout the 18-month study. The CGMS group were asked to wear the device three times during the first 3 months of the trial and on another three occasions thereafter. The GlucoWatch group wore the device a minimum of four times per month and a maximum of four times per week during the first 3 months and as desired for the remainder of the trial. Trained diabetes research nurses used downloaded data to guide therapy adjustments. Proportional reduction in HbA(1c) from baseline to 18 months was the primary outcome measure.

RESULTS

Neither an intention-to-treat nor per-protocol analysis showed improvement in HbA(1c) in the device groups compared with standard care. For the intention-to-treat analysis, when the standard care group was compared with each of the other groups, this equated to differences in mean relative HbA(1c) reduction (95% confidence interval) from baseline to 18 months of 3.5% (-1.3 to 8.3; GlucoWatch), 0.7% (-4.1 to 5.5; CGMS), and -0.1% (-4.6 to 4.3; attention control).

CONCLUSIONS

The additional information provided by these devices did not result in improvements in HbA(1c) in this population.

Cognitive behaviour therapy for violent men with antisocial personality disorder in the community: an exploratory randomized controlled trial

BACKGROUND

Little information exists on treatment effectiveness in antisocial personality disorder (ASPD). We investigated the feasibility and effectiveness of carrying out a randomized controlled trial of cognitive behaviour therapy (CBT) in men with ASPD who were aggressive.

METHOD

This was an exploratory two-centre, randomized controlled trial in a community setting. Fifty-two adult men with a diagnosis of ASPD, with acts of aggression in the 6 months prior to the study, were randomized to either treatment as usual (TAU) plus CBT, or usual treatment alone. Change over 12 months of follow-up was assessed in the occurrence of any act of aggression and also in terms of alcohol misuse, mental state, beliefs and social functioning.

RESULTS

The follow-up rate was 79%. At 12 months, both groups reported a decrease in the occurrence of any acts of verbal or physical aggression. Trends in the data, in favour of CBT, were noted for problematic drinking, social functioning and beliefs about others.

CONCLUSIONS

CBT did not improve outcomes more than usual treatment for men with ASPD who are aggressive and living in the community in this exploratory study. However, the data suggest that a larger study is required to fully assess the effectiveness of CBT in reducing aggression, alcohol misuse and improving social functioning and view of others. It is feasible to carry out a rigorous randomized controlled trial in this group.

Development and piloting of an acceptability questionnaire for continuous glucose monitoring devices

BACKGROUND

User acceptability of new health technologies is important in determining their widespread use and adoption. The aim of this current study was twofold: first, to investigate the acceptability of two continuous glucose monitoring devices for people with diabetes; and second, to develop a valid questionnaire measure to assess the acceptability of continuous glucose monitoring devices.

METHODS

Semi-structured interviews were conducted with six people with diabetes who had previously used the GlucoWatchBiographer (Animas Corp., West Chester, PA) or the CGMS continuous glucose monitoring system (Medtronic MiniMed, Northridge, CA) in order to increase understanding of the issues relating to acceptability of, and satisfaction with, the devices. Interview transcripts were analyzed qualitatively using framework analysis. These analyses, together with consultation with researchers and health professionals in the field, provided the foundation for development of a questionnaire measure that was piloted with 19 individuals.

RESULTS

Six broad themes were elicited from the framework analysis: interference with daily activities; reliability and accuracy of the devices; practicality and ease of use; improvements in glycemic control; side effects; and self-consciousness and disclosure. Piloting of the questionnaire arising from this analysis demonstrated face validity. Further psychometric testing of the questionnaire will be conducted as part of a randomized controlled trial evaluating the clinical efficacy and cost-effectiveness of the CGMS and GlucoWatch G2 Biographer.

CONCLUSIONS

Ultimately it is the user's preferences and his or her assessment of acceptability that will determine uptake and use of continuous glucose monitoring devices. It is therefore essential to consider and evaluate this alongside clinical efficacy and cost-effectiveness.

Mechanics of the passive knee joint. Part 2: interaction between the ligaments and the articular surfaces in guiding the joint motion

The aim of this study was to examine how the interaction between ligament tensions and contact forces guides the knee joint through its specific pattern of passive motion. A computer model was built based on cadaver data. The passive motion and the ligament lengthening and force patterns predicted by the model were verified with data from the literature. The contribution of each ligament and contact force was measured in terms of the rotational moment that it produced about the tibial medial plateau and the anterior-posterior (AP) force that it exerted on the tibia. The high tension of the anterior cruciate ligament (ACL) and the geometric constraints of the anterior horns of the menisci were found to be key features that stabilized the knee at full extension. The mutual effect of the cruciates was found as the reason for the screw-home mechanism at early flexion. Past 300, the AP component of contact force on the convex geometry of the lateral tibial plateau and tension of the lateral collateral ligament (LCL) were identified as elements that control the joint motion. From 60 degrees to 90 degrees, reduction in the tension of the ACL was determined as a reason for continuation of the tibial anterior translation. From 90 degrees to 120 degrees, increase in the tension of the posterior cruciate ligament and the AP component of the contact force on the convex geometry of the lateral tibial plateau pushed the tibia more anteriorly. This anterior translation was limited by the constraining effects of the ACL tension and the AP component of the contact force on the medial meniscus. The important guiding role observed for the LCL suggests that it should not be overlooked in knee models.

On the origin of the invasive olives (Olea europaea L., Oleaceae)

The olive tree (Olea europaea) has successfully invaded several regions in Australia and Pacific islands. Two olive subspecies (subspp. europaea and cuspidata) were first introduced in these areas during the nineteenth century. In the present study, we determine the origin of invasive olives and investigate the importance of historical effects on the genetic diversity of populations. Four invasive populations from Australia and Hawaii were characterized using eight nuclear DNA microsatellites, plastid DNA markers as well as ITS-1 sequences. Based on these data, their genetic similarity with native populations was investigated, and it was determined that East Australian and Hawaiian populations (subsp. cuspidata) have originated from southern Africa while South Australian populations (subsp. europaea) have mostly derived from western or central Mediterranean cultivars. Invasive populations of subsp. cuspidata showed significant loss of genetic diversity in comparison to a putative source population, and a recent bottleneck was evidenced in Hawaii. Conversely, invasive populations of subsp. europaea did not display significant loss of genetic diversity in comparison to a native Mediterranean population. Different histories of invasion were inferred for these two taxa with multiple cultivars introduced restoring gene diversity for europaea and a single successful founder event and sequential introductions to East Australia and then Hawaii for cuspidata. Furthermore, one hybrid (cuspidata x europaea) was identified in East Australia. The importance of hybridizations in the future evolution of the olive invasiveness remains to be investigated.

Mechanics of the passive knee joint. Part 1: The role of the tibial articular surfaces in guiding the passive motion

The motion of the unloaded knee is associated with tibial internal rotation and femoral posterior translation. Although it is known that the passive motion is the result of the interaction between the articular surfaces and the ligaments, the mechanism through which the particular pattern of motion is guided is not completely understood. The goal of this study was to focus on the tibial geometry and to identify the roles that its geometric features have in guiding the passive knee motion. The method used in this study simplified the geometry of the tibial plateaux and the menisci into basic features that could be eliminated individually. The generated tibial geometry was implemented in a computer model to simulate the passive motion. Different parts of the geometry were eliminated individually and the comparison between the simulation results was used to identify the role that each part of the geometry had in guiding the passive motion. The medial meniscus was found as the feature that promoted the tibial internal rotation and restrained the femoral posterior translation. The lateral meniscus and the medial aspect of the tibial eminence, on the other hand, were found as the elements that confined the tibial internal rotation.

Efficacy and safety of bimatoprost in patients with elevated intraocular pressure: a 30-day comparison with latanoprost

PURPOSE

To compare the safety and efficacy of bimatoprost and latanoprost in patients with primary open-angle glaucoma or ocular hypertension.

METHODS

This was a 30-day, multicenter, double-masked, randomized, clinical trial. Patients (n = 64) diagnosed with primary open-angle glaucoma or ocular hypertension were randomly assigned to receive bimatoprost 0.03%, latanoprost 0.005%, or vehicle topically in both eyes once daily, in the evening, for 29 days. The primary endpoint was the reduction in IOP from baseline on day 14 and day 29. Secondary outcome measures included eye examinations and safety parameters.

RESULTS

Bimatoprost and latanoprost significantly lowered IOP from baseline (p <.001). Bimatoprost lowered IOP more than latanoprost at every timepoint measured (bimatoprost: 25-34% reduction, 5.9-8.9 mm Hg; latanoprost: 20-31% reduction, 4.4-7.9 mm Hg), although the between-group differences did not reach statistical significance. Over the 12-hour course of IOP measurements on day 29, bimatoprost provided better diurnal IOP control than latanoprost (p =.0378, area under the curve of diurnal IOP reductions, 1-way ANOVA with pairwise t-test). Both treatment regimens were safe and well tolerated, with no significant between-group differences in reports of specific adverse events. The most common side effect was conjunctival hyperemia, which was similarly apparent in the bimatoprost and latanoprost treatment groups.

CONCLUSIONS

At the end of this 30-day trial, once-daily bimatoprost 0.03% provided better diurnal IOP control than latanoprost and was safe and well tolerated in patients with ocular hypertension and glaucoma.

Echocardiographic validation of gated SPECT ventricular function measurements

Left ventricular (LV) volumes are valuable prognostic indicators in the management of coronary artery disease and traditionally have been obtained by x-ray contrast angiography or echocardiography. There now are several scintigraphic methods to compute volumes that are based on different LV modeling assumptions. Both the reasons that calculations from different nuclear techniques can disagree with one another and the relationship of these values to the more conventional echocardiographic measurements must be investigated thoroughly for calculations to be interpretable for individual patients.

METHODS

Echocardiographic volumes were determined in 33 retrospective subjects with coronary artery disease (mean age, 61 +/- 12 y; 42% men; 70% with abnormal perfusion and 58% with abnormal segmental wall motion) using the modified Simpson's rule technique applied to digitized apical 4-chamber and apical 2-chamber views of 4 averaged heartbeats. These volumes were compared with those from 3 gated SPECT methods based on Simpson's rule LV modeling similar to standard echocardiographic algorithms (SPECT EF from St. Luke's-Roosevelt Hospital) (method 1), Gaussian myocardial count profile curve fitting (QGS from Cedars-Sinai Medical Center) (method 2), and an endocardial model based on perfusion sampling and count-based thickening (Cardiac Toolbox from Emory University) (method 3).

RESULTS

By ANOVA, there were no significant differences among ejection fractions (EFs), but there were for volumes. Paired t test analysis showed volumes from methods 2 and 3 to be significantly larger than echocardiographic volumes and larger than those of method 1. Linear regression analysis comparing gated SPECT and echocardiographic volumes showed a nearly identical strong correlation (r = 0.92; P < 0.000001) for all 3 methods. Excellent correlation also was found among gated SPECT volumes from the 3 methods (r = 0.94). Bland-Altman analysis and t tests showed that method 1 volumes (70 +/- 61 mL) were the same as for echocardiography (77 +/- 55 mL), but volumes were overestimated by method 2 (105 +/- 74 mL) and method 3 (127 +/- 92 mL), particularly for larger volumes. Pearson coefficients for EFs compared with echocardiography were r = 0.82, 0.75, and 0.72 for methods 1-3, respectively. EFs correlated strongly among the 3 gated SPECT methods (r = 0.86-0.92). The Fisher z test showed no differences among these methods for any of the volume or EF linear correlation analyses.

CONCLUSION

All gated SPECT parameters correlated well with echocardiographic values. However, the gated SPECT method for which underlying assumptions most closely resembled those commonly used in echocardiography produced mean volume values closest in agreement with echocardiographic measurements.

Mechanical properties of medical grade expanded polytetrafluoroethylene: the effects of internodal distance, density, and displacement rate

Expanded polytetrafluoroethylene (e-PTFE) is used successfully in a multitude of biomedical and clinical applications. The success of this biomaterial is due to its microporous structure that allows biointegration for fixation, as well as overall mechanical integrity. The mechanical properties and degree of tissue ingrowth depend on the microstructure of the expanded polymer foam, yet little is known about the correlation of the internodal distance and other microstructural features with the monotonic tensile properties. Complete structure-property correlation can be used to provide invaluable knowledge for the design of biomedical devices. The purpose of this study was to investigate the monotonic tensile properties of e-PTFE over a range of medically relevant microstructural features and manufacturing parameters. The microstructural and manufacturing parameters considered were internodal distance, linear density, volumetric density, and reduction ratio. Additionally, the effect of displacement rate on mechanical properties was studied. We found that the ultimate stress and strain increased linearly with linear density (R2 = 0.88 and 0.67, respectively). Surprisingly, elastic modulus did not correlate with any parameter measured and only weak correlations were found between all properties and internodal distance. The yield and ultimate stresses increased with increasing displacement rate (R2 = 0.88 and 0.57, respectively). The findings from this study indicate that linear density is a better predictor of mechanical properties than internodal distance and may be the preferred parameter to control when specifying a material for implantation in load bearing situations.

Linkage and LOH studies in 19 cylindromatosis families show no evidence of genetic heterogeneity and refine the CYLD locus on chromosome 16q12-q13

Familial cylindromatosis is an autosomal dominant predisposition to multiple neoplasms of the skin appendages. The susceptibility gene has previously been mapped to chromosome 16q12-q13 and has features of a recessive oncogene/tumour suppressor gene. We have now evaluated 19 families with this disease by a combination of genetic linkage analysis and loss of heterozygosity in cylindromas from affected individuals. All 15 informative families show linkage to this locus, providing no evidence for genetic heterogeneity. Recombinant mapping has placed the gene in an interval of approximately 1 Mb. There is no evidence, between families, of haplotype sharing that might be indicative of common founder mutations.

Comparison of the tetrazolium salt assay for succinate dehydrogenase with the cytosensor microphysiometer in the assessment of compound toxicities

The cytosensor microphysiometer (a biosensing instrument for detecting cellular metabolism) was compared to the established tetrazolium salt assay as a chemosensitivity test. Two coumarin compounds, 7-hydroxycoumarin and esculetin, were examined to determine their effect on the cellular metabolism of A431 cells over a 24-h exposure period. In the tetrazolium salt assay, 7-hydroxycoumarin caused suppression of the succinate dehydrogenase activity at concentrations greater than 10 microg/ml. Esculetin exerted a more serious effect on succinate dehydrogenase, with decreases in activity observed at greater than 1 microg/ml. The observed effect was dose-dependent for both compounds examined. The metabolic activities of cells exposed to 100 microg/ml of drug were 90.37 +/- 2.8 and 71.62 +/- 2.96 (n = 3), of control values, for 7-hydroxycoumarin and esculetin, respectively. Using the cytosensor microphysiometer to assess metabolic activities, a similar pattern of inhibition was observed, with esculetin more detrimental to cellular metabolism than 7-hydroxycoumarin. The effect was dose- and time-dependent for both compounds. 7-Hydroxycoumarin (100 microg/ml) caused the cellular metabolic rate to drop to 44.21 +/- 5.34% (n = 4) of the control metabolic rate, while 100 microg/ml esculetin caused the metabolic rate to fall to 21.5 +/- 4.54% (n = 4) of the control rate. The cytosensor method proved to be superior to the tetrazolium salt assay for a number of reasons, which are discussed in this paper.

Repression at a distance by the global regulator KorB of promiscuous IncP plasmids

KorB protein (358 amino acids) binds to 12 highly conserved sequences on the RK2 genome and co-ordinates the expression of at least five operons encoding genes for stable inheritance and plasmid transfer. KorB represses the trfA, korA and klaA promoters where it binds 4 bp upstream of the -35 region (class I KorB operators, OB). We show here that KorB on its own can also repress the trbA, trbB, kfrA and kleA promoters where OB is between 80 and 189 bp away from the transcription start point (class II operator). A C-terminal deletion of 17 amino acids resulted in the loss of KorB's ability to repress through class II operator but not through class I operator. This deletion reduced multimerization of His6-tailed KorB protein in vitro and greatly reduced binding specificity for fragments containing OB sequences. At the trbBp region, where OB9 lies 189 bp upstream of the transcription start point, mutagenesis of a proposed secondary binding site overlapping the trbBp -35 region had no effect on the ability of KorB to repress trbBp. Nevertheless, gel retardation analysis showed that KorB binding is promoted by sequences upstream and downstream of OB9 and that KorB can form higher order complexes on DNA. However, DNase I footprinting suggested that RNA polymerase may interact directly with KorB bound at OB9 and implied that contacts between these proteins could be responsible for the action of KorB at a distance.

ST segment elevation and the prediction of hospital life-threatening complications: the role of right ventricular and posterior leads

Accurate prognosis in suspected acute myocardial infarction (AMI) is essential for appropriate use of thrombolytic therapy and primary angioplasty. However, previous models may be limited because the 12-lead electrocardiogram (ECG) does not examine the right ventricular (RV) and posterior myocardium. We evaluated ST segment elevation (STSE) in posterior (V7-V9) and RV (V4R-V6R) leads to determine their predictive value for hospital life-threatening complications (HLTCs).

METHOD AND RESULTS

This prospective trial of seven Midwestern hospital emergency departments (EDs) had inclusion criteria of age 35 years, chest pain suggestive of ischemia, and coronary care unit (CCU) admission. ECG leads were test positive if STSE was > 0.1 mV. Patients were positive for HLTCs if ED or inpatient hospital course included: ventricular fibrillation or tachycardia, second- or third-degree block, shock, arrest, or death. Univariate and multivariate analyses were performed to test each lead's association with HLTCs. Of 533 patients, 64.7% (345/533) had AMI and 15.8% (85/533) had HLTCs. The sensitivity of 18 leads for HLTCS was increased by 5.8%, but specificity decreased by 8.2%. ECG subgroups by STSE were associated with the following HLTC rates: inferior/+RV (32.4%); anterior (29.5%), lateral (23.1%), inferior RV (17.9%), and posterior (16.2%). V1 (odds = 3.2) and V6R (odds = 3.1) were statistically significant independent predictors.

CONCLUSION

Posterior and RV leads did not increase the ECG's overall prognostic value, but in the presence of inferior STSE, were associated with low and high complication rates, respectively. Right and left precordial leads were the best predictors of HTLCs.

Evaluation of expanded polytetrafluoroethylene as a soft-tissue filling substance: an analysis of design-related implant behavior using the porcine skin model

Soft-tissue augmentation using the synthetic nonfluid biomaterial expanded polytetrafluoroethylene (ePTFE) has been supported by number of recent reports citing the favorable characteristics of biocompatibility, soft and natural feel, ease of use, and permanent augmentation. Concern has been expressed about this application for ePTFE material because of the proximity of the implants to the skin surface and potential problems with infection and extrusion. We evaluated the behavior of a series of specific ePTFE implant designs using a long-term subcutaneous augmentation model. By using a porcine model, 466 implants of ePTFE in the form of strips, rolls, or tubes were placed using a percutaneous insertion device subcutaneously over the dorsum and face. The animals were divided into three study groups by length of implantation (3 weeks, control; 6 months, intermediate term; and 12 months, long-term) and en-bloc tissue specimens, including skin, implants, and underlying soft tissue, were harvested for gross and histologic examination. Implants were removed at the earliest sign of infection, exposure, or extrusion and the difficulty of removal was ascertained and recorded. These data reveal that ePTFE material elicits acceptable levels of tissue activity with low extrusion rates over the short and long term supporting its use for soft-tissue augmentation. The data show a clear difference, however, in the host response and behavior of the implants for this application based on shape or design. A statistically significant difference in the low, but measurable, extrusion rates was observed amongst these implant designs. ePTFE tubes showed greater stability and predictable augmentation over other implant designs for soft-tissue augmentation and seem to represent a substantial improvement for this application.

The patient alert system--pilot study of built-in warning systems for pacemakers

Malfunction of a pacing system can be life-threatening for a pacemaker-dependent patient. It would be desirable for implantable pulse generators to have a built-in automatic warning system capable of alerting the patient as soon as a potentially dangerous disorder is detected. In this study, seven patients (mean age, 72.6 +/- 10.7 years) with slow, chronic atrial fibrillation underwent implantation of a dual-chamber pulse generator with a custom-made "alert electrode" connected to the atrial port of the pulse generator to stimulate the underlying pectoral muscle. The muscle was temporarily stimulated while the pacemaker was in VVIR mode. The lowest amplitude sufficient to alert the patient (perception threshold) was 1.6 +/- 0.58 V at 0.45 ms during implantation and 1.2 +/- 0.5 V at 0.45 ms chronically. In a second phase, alerts outside of the office were issued using a special software routine capable of delivering stimuli at programmable date and time.