Hybrid delivery of cluster-set resistance training for individuals previously treated for lung cancer: the results of a single-arm feasibility trial

BACKGROUND

Individuals with non-small cell lung cancer (NSCLC) are burdened by long-lasting symptoms (e.g., dyspnea and fatigue) post-treatment. These symptoms often reduce physical activity levels and increase the risk of functional decline. Though we have previously proposed cluster-set resistance training to mitigate symptom burden in lung cancer, there is currently no data on the feasibility or acceptability of this mode of exercise in cancer. Therefore, the purpose of this study was to investigate the feasibility and acceptability of a hybrid-delivery home-based cluster-set resistance training program in individuals with NSCLC stages I-III (i.e., early stage).

METHODS

This study aimed to recruit individuals with NSCLC stages I-III post-treatment to participate in 8 weeks of home-based resistance training, 3 days per week. The program included supervised sessions in the participants' homes and virtual supervision via videoconferencing. The primary outcome measure of feasibility was evaluated through recruitment, retention, and intervention fidelity (i.e., proportion of exercise completed, relative to what was prescribed). Intervention acceptability (i.e., ease and quality of virtual delivery, level of difficulty, and home-based approach) was assessed using a 4-point Likert-type scale from "strongly disagree" to "strongly agree".

RESULTS

Fourteen participants were recruited over a 6-month period, with 11 completing the intervention (2 withdrew due to unrelated illness, 1 withdrew due to requiring active treatment), yielding a retention rate of 79%. Characteristics of the participants who completed the intervention (n = 11) were as follows: mean age: 71 ± 10 years, mean BMI: 29.1 ± 6.5, and average time since diagnosis was 62 ± 51 months. Of completers, 27% were male, and 36% were Black; 10 were stage I (91%), and one was stage II (9%). Mean session attendance was 86.4 ± 9.5%. Mean intervention fidelity was 83.1 ± 13.1%. With regard to acceptability,  > 90% of participants positively rated all aspects of the intervention delivery. No adverse events related to exercise were recorded.

CONCLUSIONS

The hybrid delivery of a home-based resistance exercise program for individuals previously treated for early-stage NSCLC was found to be safe and feasible. Adaptations to the program for future interventions are required, particularly surrounding resistance exercise programming, and intervention delivery with home visits.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT05014035 . Registered January 20, 2021.

Evaluation of ocular blood flow in the assessment of symptomatic carotid stenosis

BACKGROUND AND PURPOSE

The degree of internal carotid artery (ICA) stenosis determined by criteria from the North American Symptomatic Carotid Endarterectomy Trial (NASCET) is not the most accurate index to assess distal flow compromise. Distal ICA perfusion is also determined by factors such as tandem carotid stenosis and collateral circulation. Quantification of end-organ ocular perfusion using non-invasive laser speckle flowgraphy (LSFG) may provide insights into distal ICA flow. This study prospectively assessed the degree of ICA flow using LSFG.

METHODS

Eighteen patients with symptomatic carotid stenosis underwent LSFG evaluation. LSFG was used to extract ocular blood flow metrics recorded simultaneously in the retina, choroid, and optic nerve head. The following ocular flow parameters were measured with LSFG: mean blur rate (MBR), flow acceleration index (FAI), and rising rate (RR). Syngo iFlow perfusion imaging was used to objectively quantify contrast flow in the ICA and brain parenchyma during digital subtraction angiography. Time to peak (TTP) and contrast delay were extracted from seven different regions of interest (ROIs).

RESULTS

MBR, FAI, and RR were correlated with NASCET degree of stenosis. FAI and RR also improved after stenting. TTP improved after stenting in three ROIs. A moderate negative correlation was observed between FAI and contrast delay.

CONCLUSIONS

LSFG non-invasively quantifies end-organ blood flow distal to the ICA origin. LSFG metrics have the potential to quantify end-organ perfusion and determine if a proximal carotid stenosis is symptomatic.

Abstract WP133: Assessing Aneurysmal Rupture Outcomes Using Automated Quantification Of Hemorrhage Volume

Introduction: Hemorrhage volume affects the risk of developing complications after aneurysmal subarachnoid hemorrhage (aSAH). This volume is quantified subjectively through the Fisher Scale. We developed an automated method to quantify intracranial hemorrhage and determine the risk of complications after aSAH.

Methods: CT scans of patients with aSAH were analyzed. An image-processing algorithm was designed in MATLAB to quantify aSAH volume. The automated algorithm was developed with region-growing and 3D k-means clustering. Two independent raters manually measured hemorrhage volumes using PACS and correlated these measurements with the algorithm measurements in ten patients. Vasospasm and hydrocephalus were identified through chart and imaging review. Hydrocephalus was adjudicated as ventricular enlargement in the setting of aSAH. ROC analysis was performed to evaluate the association between blood volume and the incidence of vasospasm, hydrocephalus and need for a permanent ventriculoperitoneal (VP) shunt.

Results: One hundred and forty-one patients were included in the analysis. The intraclass coefficient correlation (ICC) for inter-rater agreement in PACS was 0.988 (p < 0.001). The ICC for comparing automated versus manual volumes was 0.966 (p < 0.001). Bland-Altman analysis reported a mean difference of -3.14 mL between automated and manual measurements. Hemorrhage volume discriminated for the development of vasospasm (AUC = 0.692), hydrocephalus (AUC = 0.775), and need of permanent VP shunt (AUC = 0.669).

Conclusion: Vasospasm and hydrocephalus were associated with higher volume of aSAH. Patients with higher volume of aSAH at presentation were more likely to require a permanent VP shunt. An objective method to automatically measure aSAH volume can aid in assessing risk of complications among patients with aSAH.

Abstract TP89: Ldl Levels May Correlate With Intracranial Atherosclerotic Plaque Enhancement

Introduction: The enhancement of atherosclerotic plaques after the intravenous administration of gadolinium (Gd) has been correlated with the presence of culprit plaques in patients with acute strokes due to underlying intracranial atherosclerosis (ICAS). A new method to objectively quantify Gd-enhancement was used to monitor plaques over time after an acute stroke. Currently there is no imaging method to accurately monitor atherosclerotic activity.

Methods: Patients with stroke or transient ischemic attack caused by ICAS were included. Every patient was started on high-dose statins after ictus. 7T MRI images were obtained at baseline and after at least 6 months. LDL levels were obtained at the time of the event and at follow-up. Culprit plaques were identified based on degree of stenosis, presence of positive remodeling and Gd-enhancement. Arterial 3D enhancement maps in the territory of the culprit plaque were generated. Orthogonal signal intensity (SI) probes were expanded into the plaque and parent vessel to generate 3D enhancement color maps. Arterial segment variance (ASV) (SD 2 Arterial segment Baseline T1+Gd - SD 2 Arterial segment Follow up T1+Gd ) was used to compare the plaque and parent vessel enhancement.

Results: Five patients underwent baseline and follow-up imaging. The median time between scans was 13.3 (IQR=13.3) months. ASV was strongly correlated with changes in LDL (Rho=0.9, p=0.037). Additionally, Gd-enhancement and plaque burden correlated with levels of LDL (Figure): Gd uptake (Rho=0.7, p=0.22) and plaque burden (Rho=0.67, p=0.22).

Conclusion: This pilot study demonstrates that high-resolution imaging can be used in determining the response to statins in patients with high atherosclerotic burden. Gd-enhancement and plaque burden correlated with serum values of LDL. 3D enhancement maps and histogram analysis of atherosclerotic plaques are promising tools for evaluating disease activity and response to medical therapy.

Calcaneal Osteotomy and First Ray Procedures Improves Talar Head Coverage in the Absence of Lateral Column Lengthening

Category:

Hindfoot; Midfoot/Forefoot

Introduction/ Purpose:

Peritalar subluxation (PTS) is a crucial feature of Progressive Collapsing Foot Deformity (PCFD). Surrounding structures assume distinct behaviors, contributing to different disease deformities (classes). One of its most traditional aspects is the midfoot abduction (class B), usually noted by a lateral deviation of distal structures at the talonavicular joint. This finding commonly leads surgeons to perform a lateral column lengthening osteotomy for abduction correction, a complex surgery with potential complications. The first ray's ability to reestablish the tripod and restore the hindfoot by derotating structures under the talus was previously theorized. This study aimed to test the capability of the Lapidus and the Cotton procedures in conjunction with a calcaneus displacement osteotomy (MDCO) to improve midfoot abduction in the setting of a collapsed foot.

Methods:

In this IRB-approved, prospective cohort study, we analyzed patients undergoing medial column instability surgery and evaluated preoperatively with a weight-bearing CT (WBCT). We included individuals receiving a Lapidus bone block procedure or a Cotton for PCFD or Hallux Valgus (HV). Patients having a lateral column lengthening procedure of any type were excluded. Talonavicular coverage angle (TNCA) was measured as a marker of midfoot abduction. Medial arch collapse and forefoot varus were evaluated by the sagittal talus-first metatarsal angle (TFMA), and the forefoot arch angle (FFA) was measured. Associated procedures and the correction amount (displacement or wedge size) were recorded. Normality was estimated by the Shapiro- Wilk test and comparison among timelines by the one-way ANOVA. A multivariate regression analysis was executed to evaluate which of the measurements influenced abduction improvement. Statistical significance was considered for p-values of less than 0.05.

Results:

A total of 20 patients (age: 43.85 [19-72], BMI 30.98 [SD: 5.95]) were included, 11 PCFD (55%) and 9 HV (45%) with a mean follow-up of 7.5 months (3-12). Bone block Lapidus was performed in most subjects (90%), and the median wedge used was 9mm (5-12mm). MDCO occurred in 55% of patients. All measured variables had improvement with surgery (TNCA: 23.74 to 10.66, p< 0.0001; FFA: 6.27 to 12.67, p< 0.0001; TFMA: 11.73 to 4.22, p=0.0003). A correlation was found between TNCA improvement and FFA improvement (rs=0.46, p=0.0407), but not among TNCA improvement and TFMA improvement (rs=0.43, p=0.06). The size of the wedge did not strongly influence the TNCA correction (R2=0.016, p=0.0036), an improvement moderately explained by the MDCO amount (R2=0.186, p< 0.0001).

Conclusion:

This study demonstrated correction of midfoot abduction, translated by the TNCA, in the absence of lateral column lengthening procedures. When evaluating patients submitted to first ray procedures (bone block Lapidus and Cotton) in conjunction with MDCO, an enhancement on the talar head coverage was noted. Variables associated with arch height and forefoot varus (FFA and TFMA) were correlated with the TNCA improvement. Nevertheless, only the MDCO displacement amount and not the size of the used allograft wedge could explain changes in TNCA. The provided data might support surgeons when planning treatment in the PCFD scenario.

Small-world complex network generation on a digital quantum processor

Quantum cellular automata (QCA) evolve qubits in a quantum circuit depending only on the states of their neighborhoods and model how rich physical complexity can emerge from a simple set of underlying dynamical rules. The inability of classical computers to simulate large quantum systems hinders the elucidation of quantum cellular automata, but quantum computers offer an ideal simulation platform. Here, we experimentally realize QCA on a digital quantum processor, simulating a one-dimensional Goldilocks rule on chains of up to 23 superconducting qubits. We calculate calibrated and error-mitigated population dynamics and complex network measures, which indicate the formation of small-world mutual information networks. These networks decohere at fixed circuit depth independent of system size, the largest of which corresponding to 1,056 two-qubit gates. Such computations may enable the employment of QCA in applications like the simulation of strongly-correlated matter or beyond-classical computational demonstrations.

Study protocol: investigating the feasibility of a hybrid delivery of home-based cluster set resistance training for individuals previously treated for lung cancer

Background

Symptom burden remains a critical concern for individuals with non-small cell lung cancer (NSCLC) following the completion of treatment. The most common symptom clusters, dyspnea (shortness of breath) and fatigue, can contribute to physical decline, reductions in quality of life, and a higher risk of comorbidities and mortality. Dyspnea is a primary limiter of exercise capacity in individuals with lung cancer, resulting in exercise avoidance and an accelerated physical decline. As such, designing resistance training with cluster sets to mitigate symptoms of dyspnea and fatigue may result in improved exercise tolerance. Thus, maintaining the exercise stimulus via cluster sets, combined with improved tolerance of the exercise, could result in the maintenance of physical function and quality of life. The purpose of this study is to investigate the feasibility and preliminary efficacy of a hybrid-delivery home-based cluster-set resistance training program in individuals with NSCLC.

Methods

Individuals with NSCLC (n = 15), within 12 months of completion of treatment, will be recruited to participate in this single-arm feasibility trial. Participants will complete 8 weeks of home-based resistance training designed to minimize dyspnea and fatigue. The hybrid delivery of the program will include supervised sessions in the participants’ home and virtual supervision via video conferencing. The primary outcome of feasibility will be quantified by recruitment rates, retention, acceptability, and intervention fidelity. Exploratory outcomes (dyspnea, fatigue, quality of life, physical function, and body composition) will be assessed pre- and post-intervention.

Discussion

This study will provide important data on the feasibility of delivering this intervention and inform procedures for a future randomized controlled trial.

Trial registration

Record not yet public

Patient Experiences With Telemedicine in a National Health Service Rheumatology Outpatient Department During Coronavirus Disease-19

The coronavirus disease-19 pandemic changed rheumatology practice with remote consultations being increasingly utilized where appropriate. We evaluated patient experiences with telephone consultations and report on patient attitudes toward current health care delivery and perspectives of telemedicine in a UK National Health Service rheumatology outpatient department. We analyzed 297 questionnaires from a postal survey conducted during the summer of 2020 after a telephone follow-up consultation. The mean age of respondents was 67 years and 68% were female. The 161 respondents (54%) reported it was their first telephone consultation and overall, 239 (84%) were satisfied with their health assessment. 60% would be happy to have future routine follow-up telephone consultations. Patients advised to shield shared similar satisfaction to the whole sample. However, with increasing age we identified a higher proportion were dissatisfied with telephone consultations and unlikely to have accessibility to video consultation or preferentially opt for this modality.

An Evaluation of Agreement of Breathing Rates Measured by a Novel Device, Manual Counting, and Other Techniques Used in Clinical Practice: Protocol for the Observational VENTILATE Study

BACKGROUND

Respiratory rate (RR) is the most sensitive physiological observation to predict clinical deterioration on hospital wards, and poor clinical monitoring has been highlighted as a primary contributor to avoidable mortality. Patients in intensive care have their RR monitored continuously, but this equipment is rarely available on general hospital wards.

OBJECTIVE

The primary objective is to assess the accuracy of the RespiraSense device in comparison with other methods currently used in clinical practice. The secondary objective is to assess the accuracy of the RespiraSense device in participants in different positions and when reading aloud.

METHODS

A single-center, prospective observational study will investigate the agreement of the RespiraSense device as compared with other device measurements (capnography, electrocardiogram) and the current standard measurement of RR (manual counting by a trained health care professional). The different methods will be employed concurrently on the same participant as part of a single study visit.

RESULTS

Recruitment to this study has not yet started as funding decisions are still pending. Therefore, results are not available at this stage. It is anticipated that the data required could be collected within 2 months of first recruitment to the study and data analysis completed within 6 months of the study start date.

CONCLUSIONS

The Evaluation of Agreement of Breathing Rates Measured by a Novel Device, Manual Counting, and Other Techniques Used in Clinical Practice (VENTILATE) study will provide further validation of the use of the RespiraSense device in subjects with abnormal respiratory rates.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/15437.

Acute Effect of Cluster and Traditional Set Configurations on Myokines Associated with Hypertrophy

This study compared the acute cytokine response, and kinetic and kinematic profile following back squat exercise in resistance-trained men. In a randomized, cross-over design, 10 resistance-trained men (27±4 y, 1.80±0.07 m, 82.8±6.7 kg, 16.3±3.5% fat) performed the back squat exercise using traditional and cluster set configurations. Kinetic and kinematic data were sampled throughout each condition. Venous blood was sampled prior, immediately post, 30 min, 60 min, 24 h, and 48 h post-exercise for plasma interleukin-6 (IL-6) and interleukin-15 (IL-15). Cluster sets allowed for greater mean power (mean difference, 110 W; 90% confidence interval, ±63 W; benefit odds, 41 447:1), driven by higher overall mean velocities (0.053 m∙s^-1; 0.039 m∙s^-1; 3 105:1) as evidenced by the lack of clear contrasts for mean force. IL-15 increased post-exercise in both conditions, but increased at 24 h (0.13 pg·mL^-1; ±0.11 pg·mL^-1; 486:1) and 48 h (0.12 pg·mL^-1; ±0.10 pg·mL^-1; 667:1) in traditional sets only. IL-6 increased similarly in both conditions, post-exercise through 60 min post. Cluster set configurations allow for greater mean power, attributed to higher velocities. Despite a similar response of IL-6, traditional set configuration may provide a greater stimulus for hypertrophy as evidenced by a secondary increase in IL-15.

RANEY® cobalt--an underutilised reagent for the selective cleavage of C-X and N-O bonds

RANEY® cobalt, which was first prepared in the 1930s, is known to function effectively as a catalyst for certain chemoselective reductions. However, its utility in chemical synthesis does not seem to have been fully appreciated. This first comprehensive survey of the literature on chemical transformations involving RANEY® cobalt attempts to redress matters by, among other things, highlighting the differences between the performance of this system and its much more well-known but usually less selective congener RANEY® nickel. A reliable method for preparing consistently effective RANEY® cobalt is presented together with a protocol that avoids the need to use it with high pressures of dihydrogen. As such, it is hoped more attention will now be accorded to the title reagent that offers considerable promise as a powerful tool for chemical synthesis, particularly in the assembly of polycyclic frameworks through tandem reductive cyclisation processes.

Assessment of power, speed, and agility in athletic, preadolescent youth

AIM

The aim of this report was to assess power, speed, and agility in athletic, preadolescent youth, and determine how agility related to muscular strength and power.

METHODS

Boys (N.=53) and girls (N.=104) completed vertical jump (VJ), standing long jump (SLJ), seated medicine ball throw (SMBT), proagility shuttle run (PRO), partial curl-ups (CURL), and 20 yd sprint (20 SP). One-way analysis of variance for gender comparison and multiple regression analysis for determining association among tests were used.

RESULTS

No gender differences (P>0.05) existed for VJ or PRO. However, boys performed better on SLJ (P=0.03; 162.61+24.64 vs.154.51+20.78 cm), 20 SP (P=0.001; 3.70+0.35 vs. 3.96+0.33 s), and CURL (P=0.02; 35.16+9.67 vs. 31.48+8.80) while girls scored higher on SMBT (P=0.001; 340.46+68.58 vs. 287.12+56.39 cm). Among girls, PRO was correlated (P<0.01) with SLJ (r=-0.70) and VJ (r=-0.67). In boys, correlations (P<0.01) existed between VJ and SLJ (r=0.73) and 20 SP and PRO (r=0.72).

CONCLUSION

The current study supports previous research that found a correlation between SLJ and VJ. SLJ, VJ and SP were significant predictors of PRO, accounting for 55%, 46%, and 43% of the variation, respectively. The PRO agility test is easy to administer and requires lower body strength and power necessary for the quick changes in direction inherent to ground-based field sports. When designing a performance-related test battery for young athletes, PRO, SLJ, and VJ are effective measures and worthy of inclusion.

Retrospective analysis of serum valproate levels and need for an antidepressant drug

We sought to determine whether patients receiving valproate plus an antidepressant had significantly lower serum valproate levels before initiation of the antidepressant than those patients receiving valproate without an antidepressant. We further sought to identify the prevalence of antidepressant-induced mania and to determine if valproate provided a protective effect against antidepressant-induced mania. A computer database search from January 1, 1990-June 30, 1998, identified patients with bipolar or schizoaffective disorder treated with valproate. Patients receiving an antidepressant during valproate therapy were identified as the treatment group (9 patients), and the remaining patients served as the control group (17 patients). Serum valproate levels were recorded just before starting the antidepressant for the treatment group and monthly during a comparable period for the control group. The mean time to antidepressant initiation was 15 +/- 8 weeks. The mean serum valproate level just before antidepressant initiation was significantly lower for the treatment group compared with the mean serum valproate level averaged over 16 +/- 6 weeks for the control group (54 +/- 24 vs 73 +/- 13 microg/ml, p<0.05). Four patients (44%) developed antidepressant-induced mania. Three required discontinuation of the antidepressant; their serum valproate levels were 54, 60, and 71 microg/ml. Patients requiring the addition of an antidepressant had significantly lower valproate serum levels than those who did not require an antidepressant. Further study is necessary to determine whether higher serum valproate levels are needed for prevention of depressive symptoms in bipolar and schizoaffective disorders.

A critical review of published economic modelling studies in depression

Depression is a very costly chronic disease. An important cost driver is treatment failure caused by patient noncompliance due, in part, to the adverse effects of medications. Additionally, inadequate duration of therapy and inappropriate medication switching contribute to the high cost of treatment. With the epidemiological data for depression demonstrating a rise in both incidence and prevalence over the last 20 years, and the fact that many of the newer antidepressants will see patent expiry in the near future, previous antidepressant cost-effectiveness scenarios are likely to change. As economic models play an increasingly important role in therapeutic decision-making, clinicians are encouraged to understand the strategies and methods involved in modelling antidepressant therapy. The aim of this review of the literature and synthesis of the various techniques important to the modelling of antidepressant therapies is for the practitioner to gain an increased understanding of the modelling methods previously utilised and be in a position to better evaluate future health economic models for the treatment of depression.

Pharmacist-designed and -implemented pharmaceutical care plan for antipsychotic-induced movement disorders

We developed a systematic approach to assess the presence, severity, and management of extrapyramidal symptoms (EPS) in patients treated with antipsychotics. Patients were evaluated by the Modified Simpson-Angus scale, Abnormal Involuntary Movement Scale, and Dyskinesia Identification System: Condensed User Scale. We completed 235 sets of evaluations in 83 patients. A pharmaceutical intervention was proposed in 54% (130) of evaluations, of which 82% (107) were accepted and followed. In 93% (99) evaluations in which a recommendation was followed, clinical outcome was positive. The most common intervention was reducing the dosage or discontinuing the antidyskinetic agent, most often an anticholinergic (55% of cases). Our results show that detailed monitoring of EPS in a clinical pharmacist-operated clinic promotes rational drug therapy, limits unnecessary drugs, and improves clinical outcome of patients with EPS.

Coronary surgery in Europe: comparison of the national subsets of the European system for cardiac operative risk evaluation database

OBJECTIVE

To compare the national samples of patients who underwent isolated coronary artery bypass grafting (CABG) during the European System for Cardiac Operative Risk Evaluation (EuroSCORE) trial in order to evaluate national differences in epidemiology, patient risk profile and surgical methods.

METHODS

From September to November 1995, 11731 patients had CABG in the six largest contributing nations to the EuroSCORE project: Germany, UK, Spain, Finland, France and Italy. The Chi-square and Kruskal-Wallis tests were applied to obtain an international comparison of patient general status, including pre-operative risk factors, cardiac status, critical pre-operative states, rare conditions, urgency of surgery, angina status, coronary lesions, procedures and EuroSCORE risk assessment.

RESULTS

Large national samples (from 984 patients in Finland to 3138 in Germany) identified significant differences in epidemiology, risk profile and surgical practice. Regarding epidemiology, CABG accounted for 62.8% of adult cardiac surgery, with a range of 46.2 in Spain to 77.7% in Finland (P<0.001). The mean age was 62.9 years (61.4 in Britain to 64.4 in France, P<0.001). The mean body mass index was 26.8 (26 in France to 27.5 in Finland, P<0.001). With regard to risk profile, diabetes was present in 20.3% of patients (11.8% in Britain to 27.7% in Spain, P<0.001). Chronic renal failure was present in 8.3% (6.8% in Germany to 10.6% in Spain, P<0.001). Chronic airway disease affected 3.8% (1.9% in Italy to 5. 1% in Germany, P<0.001). The mean ejection fraction was 0.56 (0.48 in Britain to 0.58 in Finland, P<0.001). The mean predicted mortality (according to EuroSCORE) was 3.3% (2.8% in Finland to 3.6% in France, P<0.001). The prevalence of chronic congestive heart failure, unstable angina and recent myocardial infarction also showed statistically significant differences. No differences were found for some critical preoperative states (such as immediate preoperative cardiac massage and pre-operative intubation), or for surgery for catheter laboratory complication. Regarding surgical practice, major differences were noted in preoperative intra-aortic balloon use (mean 1%, Finland 0%, Spain 2.3%, P<0.001), the number of mammary artery conduits used (mean 0.9, Spain 0.7, France 1.1, P=0.0001) and the number of distal anastomoses (mean 3, France 2.7, Finland 3.8, P=0.001).

CONCLUSION

There are important epidemiological differences in the national cohorts of CABG patients in the EuroSCORE database. Any international comparison of European surgical results must therefore take into account the risk profile of patients by using a compatible risk stratification system.

Risk factors and outcome in European cardiac surgery: analysis of the EuroSCORE multinational database of 19030 patients

OBJECTIVE

To assess risk factors for mortality in cardiac surgical adult patients as part of a study to develop a European System for Cardiac Operative Risk Evaluation (EuroSCORE).

METHODS

From September to November 1995, information on risk factors and mortality was collected for 19030 consecutive adult patients undergoing cardiac surgery under cardiopulmonary bypass in 128 surgical centres in eight European states. Data were collected for 68 preoperative and 29 operative risk factors proven or believed to influence hospital mortality. The relationship between risk factors and outcome was assessed by univariate and logistic regression analysis.

RESULTS

Mean age (+/- standard deviation) was 62.5+/-10.7 (range 17-94 years) and 28% were female. Mean body mass index was 26.3+/-3.9. The incidence of common risk factors was as follows: hypertension 43.6%, diabetes 16.7%, extracardiac arteriopathy 2.9%, chronic renal failure 3.5%, chronic pulmonary disease 3.9%, previous cardiac surgery 7.3% and impaired left ventricular function 31.4%. Isolated coronary surgery accounted for 63.6% of all procedures, and 29.8% of patients had valve operations. Overall hospital mortality was 4.8%. Coronary surgery mortality was 3.4% In the absence of any identifiable risk factors, mortality was 0.4% for coronary surgery, 1% for mitral valve surgery, 1.1% for aortic valve surgery and 0% for atrial septal defect repair. The following risk factors were associated with increased mortality: age (P = 0.001), female gender (P = 0.001), serum creatinine (P = 0.001), extracardiac arteriopathy (P = 0.001), chronic airway disease (P = 0.006), severe neurological dysfunction (P = 0.001), previous cardiac surgery (P = 0.001), recent myocardial infarction (P = 0.001), left ventricular ejection fraction (P = 0.001), chronic congestive cardiac failure (P = 0.001), pulmonary hypertension (P = 0.001), active endocarditis (P = 0.001), unstable angina (P = 0.001), procedure urgency (P = 0.001), critical preoperative condition (P = 0.001) ventricular septal rupture (P = 0.002), noncoronary surgery (P = 0.001), thoracic aortic surgery (P = 0.001).

CONCLUSION

A number of risk factors contribute to cardiac surgical mortality in Europe. This information can be used to develop a risk stratification system for the prediction of hospital mortality and the assessment of quality of care.

Treatment of mediastinitis: early modified Robicsek closure and pectoralis major advancement flaps

BACKGROUND

The treatment of sternal wound complications is controversial. It is our practice to combine early aggressive debridement, a modified Robicsek sternal closure, and bilateral pectoralis major advancement flaps with or without closed irrigation in a single procedure. We reviewed our experience to determine the efficacy of this approach.

METHODS

Grade II to IV mediastinitis (dehiscence and infection) developed in 47 patients 3 to 14 days after routine open heart operations between 1990 and 1995. Culture-positive infection was identified in 60% (n = 28); 62% (n = 29) had septicemia. Thirty patients underwent incision, drainage, and surgical assessment of the wound. Once systemic signs of infection were under control (no pyrexia, normal white blood cell count), formal single-stage debridement of all infected soft tissues and bones was performed. Sternal stability was achieved using a modified Robicsek closure and bilateral pectoralis major advancement flaps. Seventeen patients were treated with staged procedures.

RESULTS

Early sternal closure and coverage with pectoralis major advancement flaps can be associated with a low mortality (0%), low morbidity (13%; n = 4: three superficial wound infections, one seroma), and shortened hospital stay (median, 22 days, compared with a median of 82 days in patients managed with conservative staged treatment; p < 0.05). Sternal stability with excellent functional and aesthetic results has been achieved in all patients.

CONCLUSIONS

The combination of aggressive early surgical debridement, sternal closure, and the placement of bilateral pectoralis major advancement flaps is a simple procedure associated with a low mortality and morbidity and a short hospital stay.

Rotavirus RNA polymerase requires the core shell protein to synthesize the double-stranded RNA genome

Rotavirus cores contain the double-stranded RNA (dsRNA) genome, RNA polymerase VP1, and guanylyltransferase VP3 and are enclosed within a lattice formed by the RNA-binding protein VP2. Analysis of baculovirus-expressed core-like particles (CLPs) has shown that VP1 and VP2 assemble into the simplest core-like structures with replicase activity and that VP1, but not VP3, is essential for replicase activity. To further define the role of VP1 and VP2 in the synthesis of dsRNA from viral mRNA, recombinant baculoviruses containing gene 1 (rBVg1) and gene 2 (rBVg2) of SA11 rotavirus were generated and used to express recombinant VP1 (rVP1) and rVP2, respectively. After purification, the proteins were assayed individually and together for the ability to catalyze the synthesis of dsRNA in a cell-free replication system. The results showed that dsRNA was synthesized only in assays containing rVP1 and rVP2, thus establishing that both proteins are essential for replicase activity. Even in assays containing a primer-linked mRNA template, neither rVP1 nor rVP2 alone directed RNA synthesis. Characterization of the cis-acting replication signals in mRNA recognized by the replicase of rVP1 and rVP2 showed that they were the same as those recognized by the replicase of virion-derived cores, thus excluding a role for VP3 in recognition of the mRNA template by the replicase. Analysis of RNA-protein interactions indicated that the mRNA template binds strongly to VP2 in replicase assays but that the majority of the dsRNA product neither is packaged nor stably associates with VP2. The results of replicase assays performed with mutant VP2 containing a deletion in its RNA-binding domain suggests that the essential role for VP2 in replication is linked to the protein's ability to bind the mRNA template for minus-strand synthesis.

The importance of work-up (verification) bias correction in assessing the accuracy of SPECT thallium-201 testing for the diagnosis of coronary artery disease

Noninvasive testing is often evaluated by the sensitivity and specificity in comparison with a more invasive, but more definitive "gold" standard. However, work-up or verification bias, which occurs when the results of a noninvasive test impact the decision to perform the gold standard invasive test, increases the "observed" sensitivity and decreases the "observed" specificity of the noninvasive test. Most large clinical studies utilizing a noninvasive technique to diagnose coronary artery disease have biases, particularly work-up bias. To obtain more accurate measurements of sensitivity and specificity, we determined the observed sensitivity and specificity of stress (exercise and dipyridamole) single photon emission computed tomographic (SPECT) thallium testing for the detection of coronary artery disease by angiography, and then applied previously published equations to correct for work-up bias. From a computerized data base, reports of 4354 stress SPECT thallium studies from January 1, 1986 through December 31, 1992 were reviewed. All patients with a known history of myocardial infarction or prior coronary angiography were excluded, leaving 2688 patients. From this total, 471 patients underwent coronary angiography within 90 days following stress SPECT thallium testing. Coronary artery disease was defined as a visually assessed stenosis of a coronary artery or a major branch > 50%. Of the 2688 stress SPECT thallium studies, 1265 were normal and 1423 were abnormal. For the 471 patients who underwent catheterization within 90 days following stress SPECT thallium testing. the "observed" sensitivity and specificity were 98 and 14%, respectively. After correction for work-up bias, the corrected sensitivity and specificity were 82 +/- 6% and 59 +/- 2%, respectively. Most studies utilizing noninvasive technologies for the detection of coronary artery disease include patients with known coronary artery disease and have work-up bias as well. By knowing the thallium results of patients with and without catheterization, we were able to correct for work-up bias. These data provide better estimate of the sensitivity and specificity of stress SPECT thallium testing.

Aortic valve replacement for end-stage aortic valve disease

To evaluate the outcome of surgical intervention for end-stage aortic valve disease, we carried out a retrospective, longitudinal survey of 85 patients (65 males, 20 females; mean age 53 period. All the patients presented in New York Heart Association (NYHA) class IV in cardiac failure (3 had cardiogenic shock and 27 had bacterial endocarditis). In-hospital mortality was 9.4% (8/85) overall. Those with endocarditis had a significantly higher mortality, 6/27 (22%) vs 2/58 (3.4%), p < 0.01. In-hospital mortality was not significantly increased in those with renal failure, reoperation, simultaneous coronary artery surgery, age > 65 years nor was it related to the predominance of aortic regurgitation or stenosis. After a mean follow-up period of 5.9 years (range 0 to 12.5 years), the overall actuarial survival was 82% and 74% at 5 and 10 years respectively. For 66 late survivors, the NYHA status improved to class I in 51, to II in 10, to III in 4 patients, and one patient remained in class IV. The incidence of paraprosthetic leak, reoperation, thromboembolism, anticoagulant-related haemorrhage, and endocarditis were respectively 0.8, 0.8, 1.6, 1.4, and 0.2 per 100 patient-years. Aortic valve replacement in the patient with end-stage aortic valve disease is a high-risk procedure, the risk being higher in the presence of endocarditis. The favourable long-term survival, long-term improvement in functional class and the relatively low incidence of valve-related complications justify surgical intervention in such patients, who would otherwise have a very poor prognosis.

Effect of increasing work rate on metabolic responses of the donkey (Equus asinus)

Oxygen consumption (VO2) and concentration of venous blood metabolites were measured in donkeys trained to run and to pull loads on a treadmill. VO2 in two donkeys running at maximal speed on a 9.8% slope was 110 +/- 2 ml.min-1.kg-1, approximately 22 times preexercise VO2. Average heart rate at maximal VO2 (VO2max) was 223 +/- 2 beats/min, five times the preexercise heart rate. Blood lactate increased 14-fold, and blood glucose did not change (P > 0.05). Animals running up a 4% incline and incremental draft loading of five donkeys walking on the level were also studied. The total energy cost of walking unloaded was 2.86 +/- 0.06 J.m-1.kg live wt-1. During low- to medium-intensity draft work for 25 min, glucose fell below preexercise values (P < 0.05), whereas plasma hematocrit and cortisol increased (P < 0.05). Blood lactate remained unchanged up to approximately 40% VO2 max but increased 170% at approximately 60% VO2max. The responses in donkeys are similar to those of exercising horses except for the rapid decline in blood glucose observed during low-intensity exercise and the lower lactate levels at both the high-intensity exercise and the apparent anaerobic threshold.

Histological examination of peroperative frozen sections in suspected lung cancer

BACKGROUND

Despite extensive investigations some patients with suspected lung cancer may undergo thoracotomy without preoperative histological proof of malignancy. A questionnaire on the use of histological examination of peroperative frozen sections in such patients was sent to 50 thoracic surgeons. Replies were received from 41 surgeons and indicated an absence of consensus on the usefulness of histological examination of frozen sections in this context, confirming the need for this study.

METHODS

During one year 60 consecutive patients undergoing thoracotomy for suspected lung cancer without a prior histological diagnosis were studied prospectively. At thoracotomy the surgeon assessed the lesion macroscopically and a verdict on whether it was malignant was recorded. A biopsy specimen was then taken for examination of a frozen section and the result recorded. The appropriate operation was performed and the surgeon's verdict and the report on the frozen section were compared with the definitive histological diagnosis based on a paraffin section.

RESULTS

Of 50 malignant lesions, 43 were identified by the surgeon and 47 by examination of the frozen section (sensitivity 86% and 94% respectively). Of 10 benign lesions, four were identified by the surgeon and nine by examination of the frozen section (specificity 40% and 90% respectively).

CONCLUSIONS

Clinical and macroscopic assessment at thoracotomy are inferior to examination of frozen sections in suspected lung cancer, particularly where the lesion is benign. Lung resection should not be performed without examination of peroperative frozen sections when thoracotomy is performed for suspected but unproved lung cancer.

Effect of regular voluntary exercise on resting cardiovascular responses in SHR and WKY pregnant rats

The purpose of this study was to assess the influence of regular voluntary exercise in pregnant normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats on 1) uteroplacental perfusion and mean arterial pressure in the resting conscious condition and 2) fetal number, fetal weight, and number of fetal resorptions. WKYs and SHRs were randomly assigned to standard cages [CWKY (n = 10); CSHR (n = 6)] or cages with activity wheels [EWKY (n = 7); ESHR (n = 8)]. EWKYs and ESHRs exercised for 12 wk, and then all rats were bred and experiments were conducted on gestational day 17. Resting blood flow (microspheres), heart rate (HR), and mean arterial pressure (Pa) were measured. No significant difference was found in Pa, HR, uterine blood flow (ESHRs 52 +/- 8 ml.min-1.100 g-1; CSHRs 28 +/- 6 ml.min-1.100 g-1), or maternal placental blood flow (ESHRs, 122 +/- 31 ml.min-1.100 g-1; CSHRs 78 +/- 21 ml.min-1.100 g-1) among the groups. Exercise altered the relationship between maternal placental and uterine blood flow and Pa in the SHR; SHRs with lower Pa maintained higher placental and uterine blood flow after training. Before gestation ESHRs ran on average more kilometers per week than EWKYs (43 +/- 3 vs. 34 +/- 4), but during gestation ESHRs averaged fewer kilometers per week than EWKYs (16 +/- 4 vs. 22 +/- 4). Succinate dehydrogenase activity was higher in the white vastus lateralis (1.02 +/- 0.2 mumol cytochrome c reduced.min-1.g wet wt-1) and vastus intermedius (3.1 +/- 0.5 mumol cytochrome c reduced.min-1.g wet wt-1) muscles of ESHRs.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of maximal oxygen consumption in exercising pregnant sheep

Previous work with pregnant ewes has shown that acute bouts of exercise may cause changes in plasma hormone concentrations, blood flow distribution, and maternal and fetal temperatures. However, most of these studies do not quantify the chosen exercise intensity through measurement of oxygen consumption (VO2). Therefore the purpose of this study was to statistically model the VO2 response of pregnant sheep to treadmill (TM) exercise to determine the exercise intensities (% maximal VO2) of previous studies. Ewes with either single (n = 9) or twin (n = 5) fetuses were studied from 100 to 130 days of gestation. After 1-2 wk of TM habituation, maximal VO2 (VO2max) was determined by measurements of VO2 (open flow-through method) and blood lactate concentration. VO2 was measured as a function of TM incline (0, 3, 5, and 7 degree) and speed (0.8-3.4 m/s). VO2max averaged 57 +/- 7 (SD) ml.min-1.kg-1, and peak lactate concentration during exercise averaged 22 +/- 2 mmol/l. The relationship between VO2 (ml.min-1.kg-1) and incline (INC) and speed (SP) [VO2 = 0.70(INC) + 13.95(SP) + 1.07(INC x SP) - 1.18] was linear (r2 = 0.94). Our findings suggest that most previous research used exercise intensities less than 60% VO2max and indicate the need for further research that examines the effect of exercise during pregnancy at levels greater than 60% VO2max.

Comparison of ultrasonography and oral cholecystography in lithotripsy. II. Determining retreatment

Both ultrasonography (US) and oral cholecystography (OCG) are being used to evaluate patients after extracorporeal shock wave lithotripsy (ESWL) for gallstones. Criteria for retreatment after the initial ESWL are usually related to the size of the residual fragments. This study examines the efficacy of ultrasound and OCG for determining both the size and number of stone fragments in the gallbladder in an in vitro model and in patients. Ultrasonography and OCG examinations using an in vitro ESWL phantom with ten groups of stones, and on 39 patients, were reviewed independently by three radiologists to determine both the size and number of stone fragments. For the in vitro study, the three readers estimated the correct number of fragments, or the next closest range, in 87% of observations by OCG and in 43% by US. The size of the largest fragment was measured within 1 mm of its actual size in 87% of observations by OCG and 20% by US. Correlation coefficients for the mean measurements of the three readers versus the actual fragment size and number were greater for OCG than for US. For the in vivo study, the three readers agreed in 47% of the OCG versus 32% of US examinations with respect to the number of fragments, and in 65% of OCG compared to 40% of US studies with respect to size of the largest fragment. Multiple statistical analyses demonstrate that these differences are statistically significant. A discrepancy among the readers concerning whether a patient was eligible for retreatment occurred in 15% of OCG as compared to 45% of US studies. Both the in vivo and in vitro studies indicate that there is more interobserver reproducibility for OCG than for US, and that OCG is more reliable in making the decision concerning patient eligibility for retreatment following lithotripsy.

Comparison of ultrasonography and oral cholecystography in biliary lithotripsy. I. Screening patients

Ultrasound and oral cholecystography (OCG) are both used to evaluate candidates for biliary lithotripsy. Some investigators have suggested abandoning the OCG, believing that sufficient screening information can be obtained from ultrasound. This study compares ultrasound and OCG in assessing the size and number of gallstones, both in vitro and in vivo. In the in vitro model, 35 gallstones, divided into 20 groups, were separately suspended in dilute contrast media in a phantom, and examined by ultrasound and simulated OCG by each of three gastrointestinal radiologists. In the in vivo study, the ultrasound and OCG examinations from 53 patients were independently reviewed by three radiologists. The number and size of the stones were recorded in both studies. In the in vitro study, the stone size was measured within 2 mm of the actual size by OCG in 23/35 stones (66%) and by ultrasound in 4/35 stones (11%). The correct number of stones was determined by OCG in 19/20 groups (95%), and by ultrasound in 14/20 (70%). In the in vivo study, all readers saw the same number of stones in 40/50 (80%) patients by OCG and 33/49 (67%) patients by ultrasound. Statistical analyses revealed correlation coefficients for OCG greater than those for ultrasound in each comparison. The size of the largest stone was within 2 mm by all readers in 26/51 (51%) of patients by OCG and 20/47 (43%) patients by ultrasound. Oral cholecystography is more reliable than ultrasound for the determination of size and number of stones in patients being screened for biliary lithotripsy.

Effect of maternal cocaine administration on maternal and fetal glucose, lactate, and insulin in sheep

Although cocaine use during pregnancy is an important cause of perinatal morbidity and mortality, there are no reports of its effect on maternal and fetal carbohydrate metabolism. Six pregnant ewes and their fetuses were instrumented under halothane general anesthesia at 113-119 days' gestation. Between 124-135 days' gestation, the ewes received a single infusion of vehicle or cocaine (1.0 or 2.0 mg/kg) into the jugular vein. At least 24 hours was allowed between successive injections. Maternal and fetal blood samples were drawn at 30 and 20 minutes before and at 5, 15, 30, and 60 minutes after the injection. Both maternal and fetal glucose and lactate concentrations increased (P less than .05) after injection of cocaine at 2.0 mg/kg. There were no significant changes in maternal or fetal plasma insulin concentrations after vehicle or cocaine administration. Induction of hyperglycemia and lactacidemia could be mechanisms whereby cocaine exerts its adverse effects during pregnancy.

Hypertonic citrate solution as an alternative to modified Euro-Collins' solution for lung preservation

In a canine model of acute ischemic lung injury, a hypertonic citrate solution (HTC) widely used for renal preservation in the United Kingdom, was compared with modified Euro-Collins' solution (ECS) currently the most widely clinically used pulmonary perfusate. Ten beagle dogs underwent left thoracotomy and exclusion of the left lung in situ. The lung was flushed with 30 ml/kg of either HTC or ECS and subjected to 60 min of warm ischemia. The circulation to the lung was then restored, the contralateral lung excluded, and the animal ventilated at a fixed FiO2 of 0.4 for 4 hr. Lung function was assessed by arterial oxygenation and hemodynamic measurements and, following sacrifice, by lung weight gain, bronchoalveolar lavage, and ultrastructural studies. Flush perfusion with HTC was associated with significantly less severe reperfusion injury, as determined by superior arterial oxygenation (PaO2 at 1 hr: HTC--152 mmHg [(95% confidence interval) CI] [122-182], ECS--59 [47-70]; PaO2 at 4 hr: HTC--124 [100-149], ECS--51 [42-61]), lower pulmonary vascular resistance index (PVRI at 4 hrs: HTC--838 dynes sec cm-5m-2 [651-1075], ECS--1233 [963-1588]); and lower lung weight (HTC--85 g [66-107], ECS--146 [114-184]). Bronchoalveolar lavage studies demonstrated an influx of neutrophils following reperfusion that was significantly less marked in the HTC group (increase in % neutrophils: HTC 24 [19-29], ECS 77 [72-82]). Lung injury assessed by electron microscopy tended to be less severe in the HTC animals. We conclude that HTC may offer an alternative superior to ECS for lung preservation.

Cocaine in pregnancy: the effect of maternal administration of cocaine on the maternal and fetal pituitary-adrenal axes

The effects of cocaine on the maternal and fetal pituitary-adrenal axis in vivo during pregnancy have not been reported. Six pregnant ewes and their fetuses underwent instrumentation at 113 to 119 days' gestation. Ewes were assigned to receive an intravenous bolus injection of vehicle or cocaine (0.5, 1.0, or 2.0 mg.kg-1) at 124 to 136 days' gestation. Maternal arterial blood gases, fetal pH and fetal PCO2 were unchanged after injection of cocaine or vehicle. After administration of 2.0 mg.kg-1 cocaine, arterial fetal PO2 fell 3.2 +/- 1.72 mm Hg (p less than 0.05) at +5 minutes, returning to baseline by +15 minutes. Maternal and fetal adrenocorticotropin levels rose within 5 minutes after the highest cocaine dose (p less than 0.05). There was a significant (p less than 0.05) increase in maternal cortisol at all doses of cocaine and in fetal cortisol at +15 minutes after the 2.0 mg.kg-1.

Lack of effect of fetal administration of cocaine on maternal and fetal plasma adrenocorticotropin, cortisol and lactate concentrations at 127-138 days gestational age

Few in vivo studies have attempted to characterize the effects of cocaine on the maternal and fetal pituitary-adrenal axis during pregnancy. We, therefore, administered cocaine (2 mg.kg-1) intravenously to 6 fetal sheep at 127-138 days of gestation. There was a transient reduction in fetal arterial pO2 with a concomitant increase in pCO2 and a prolonged fall in pH (p less than 0.05) following cocaine injection. No changes were seen in maternal pO2, pCO2 or pH. Maternal plasma adrenocorticotropin, cortisol and lactate were not affected by fetal administration of cocaine. Although there was a tendency for fetal plasma adrenocorticotropin, cortisol and lactate to rise after administering cocaine, the increases were not statistically significant. Previous studies have shown that cocaine administration to the ewe at a similar stage of pregnancy results in increased fetal plasma adrenocorticotropin concentrations. The results of the present study indicate that cocaine administration to the fetus compromises fetal gas exchange and acid base balance, but the effects on the fetal pituitary-adrenal axis are less pronounced than after maternal administration of cocaine.

Lack of effect of fetal administration of cocaine on maternal and fetal plasma adrenocorticotropin, cortisol and lactate concentrations at 127-138 days gestational age

Few in vivo studies have been done to characterize the effects of cocaine on the maternal and fetal pituitary-adrenal axis during pregnancy. We, therefore, administered cocaine (2 mg.kg-1) intravenously to 6 fetal sheep at 127-138 days of gestation. There was a transient reduction in fetal arterial pO2 with a concomitant increase in pCO2 and a prolonged fall in pH (p less than 0.05) following cocaine injection. No changes were seen in maternal pO2, pCO2 or pH. Maternal adrenocorticotropin (ACTH), cortisol and lactate were not affected by fetal administration of cocaine. Although there was a tendency for fetal plasma ACTH, cortisol and lactate to rise after administering cocaine, the increases were not statistically significant. Previous studies have shown that cocaine administration to the ewe at a similar stage of pregnancy results in increased fetal plasma ACTH concentrations. The results of the present study indicate that cocaine administration to the fetus compromises fetal gas exchange and acid-base balance but the effects on the fetal pituitary-adrenal axis are less pronounced than after maternal administration of cocaine.

Effects of training on reproductive tissue blood flow in exercising pregnant rats

The purpose of this study were to investigate 1) whether treadmill training would attenuate the reduction in reproductive (RBF) and visceral tissue blood flow (VBF) that occurs during an acute bout of submaximal exercise (EX) in pregnant rats and 2) whether fetal number of fetal weight would be affected by training. One group (T) of female rats trained on a treadmill (10 degrees incline, 30 m/min) for 1 h/day 5 days/wk for 10 wk before becoming pregnant. A second group (UT) was run at the same speed and incline for 10 min/day 5 days/wk for 2 wk. T and UT rats were bred until pregnant. Skeletal muscle blood flow, RBF, and VBF were measured at pre-EX and at 1 and 10 min of EX (10 degrees incline, 30 m/min). No differences were observed before or during exercise between the two groups in RBF and VBF, heart rate, or mean arterial pressure. Both groups experienced decreases in VBF (except liver) and RBF from pre-EX to EX. In most muscles skeletal muscle blood flow increased for both groups from pre-EX to EX. Neither group experienced a change in mean arterial pressure from pre-EX to EX, but heart rate increased significantly for both groups. No differences were observed between groups in fetal number, fetal weight, or fetal resorptions. It was concluded that training does not significantly attenuate the reduction in RBF and VBF in pregnant rats that occurs during an acute bout of submaximal EX and that training does not affect fetal weight or fetal number.

Biliary lithotripsy: in vitro analysis of gallstone fragmentation for equivalent stone volumes

The relationship between gallstone fragmentation during extracorporeal shock wave lithotripsy (ESWL) and gallstone volume is poorly understood. Clinical results of ESWL show that the highest stone-free rate at 6 months occurs with radiolucent single gallstones 20 mm or less in diameter. In an in vitro study, individual gallstones from cholecystectomy specimens were divided by size and composition into nine single- and nine multiple-stone groups; the stones were then paired on the basis of similar volume. ESWL was performed in a phantom and the size of the largest fragment was measured at 500, 1,000, and 1,500 shock waves. At 1,500 shock waves, sandlike particles were present in six of nine single stones versus two of nine multiple stone groups; the mean size of the largest fragment at 1,500 shock waves was 2.1 mm (single) and 4.4 mm (multiple) in diameter. When corrected for volume, the authors' data suggest that single stones are more easily broken into fragments smaller than 5 mm in diameter than multiple gallstones. The implication, especially when spark-gap technology is used, is that more shock wave energy (ie, an increased number of shock waves at a higher kilovoltage) will be necessary to achieve the same results when treating patients with multiple stones versus a single gallstone with a similar stone volume.

Distribution of blood flow during exercise after blood volume expansion in swine

To study the distribution of blood flow after blood volume expansion, seven miniature swine ran at high speed (17.6-20 km/h, estimated to require 115% of maximal O2 uptake) on a motor-driven treadmill on two occasions: once during normovolemia and once after an acute 15% blood volume expansion (homologous whole blood). O2 uptake, cardiac output, heart rate, mean arterial pressure, and distribution of blood flow (with radiolabeled microspheres) were measured at the same time during each of the exercise bouts. Maximal heart rate was identical between conditions (mean 266); mean arterial pressure was elevated during the hypovolemic exercise (149 +/- 5 vs. 137 +/- 6 mmHg). Although cardiac output was higher and arterial O2 saturation was maintained during the hypervolemic condition (10.5 +/- 0.7 vs. 9.3 +/- 0.6 l/min), O2 uptake was not different (1.74 +/- 0.08 vs. 1.74 +/- 0.09 l/min). Mean blood flows to cardiac (+12.9%), locomotory (+9.8%), and respiratory (+7.5%) muscles were all elevated during hypervolemic exercise, while visceral and brain blood flows were unchanged. Calculated resistances to flow in skeletal and cardiac muscle were not different between conditions. Under the experimental conditions of this study, O2 uptake in the miniature swine was limited at the level of the muscles during hypervolemic exercise. The results also indicate that neither intrinsic contractile properties of the heart nor coronary blood flow limits myocardial performance during normovolemic exercise, because both the pumping capacity of the heart and the coronary blood flow were elevated in the hypervolemic condition.

Prediction of oxygen uptake on a bicycle wind-loaded simulator

The primary purpose of this study was to determine the accuracy of estimating oxygen uptake (VO2) from the flywheel revolution rate of a bicycle wind-loaded simulator. VO2 at four different flywheel revolution rates was measured on a Findlay Road Machine (FRM). Ten male trained cyclists, 10 male untrained cyclists, 10 female trained cyclists and 10 female untrained cyclists served as subjects. Significant curvilinear relationships (P less than 0.01) were found between road speed estimated from flywheel revolution rate and VO2 expressed as 1.min-1, ml.kg-1.min-1, 1.min-1.m-2 (r = 0.97, 0.96, 0.98, respectively). The absolute standard error of the mean VO2 was 0.21 l.min-1 (9.6%), 3.71 ml.kg-1.min-1 (11.5%) and 0.10 l.min-1.m-2 (7.9%), respectively. The relationship between VO2 and speed was similar to that reported during road cycling. To determine the magnitude of between-machine differences in VO2, six subjects randomly performed cycling using two different FMR. Significant (P less than 0.05) differences between machines were found at only the highest speed. The present study indicates that it is possible to accurately predict VO2 from flywheel revolution rate using a FRM. Since the FRM appears to approximate the resistance a cyclist experiences on the road and allows cyclists to use their own bicycle, it provides a good alternative to traditional laboratory ergometers.

Amelioration of lung ischemic injury with prostacyclin

The single-flush technique of lung preservation is thought to be enhanced by prostaglandin treatment. In order to test this hypothesis, ten beagle dogs underwent thoracotomy and in situ flush perfusion of the excluded left lung with 30 ml/kg of cold, modified Euro-Collins' solution. Group 1 (n = 5) received pretreatment with 30 ng/kg/min of PGI2 by infusion and as an additive to the flush (20 micrograms/L). Group 2 (n = 5) received no PGI2 and served as controls. Following 60 min of warm ischemia, the left lung was reperfused, the contralateral lung excluded, and the animal ventilated at a fixed FiO2 of 0.4 for 4 hr. The severity of reperfusion injury was assessed by arterial oxygenation and hemodynamic measurements and, following sacrifice, by lung weight gain and bronchoalveolar lavage and ultrastructural studies. PGI2 therapy resulted in significant amelioration of reperfusion injury, with superior oxygenation at both 1 and 4 hr (PaO2 at 1 and 4 hr, respectively; PGI2: 145 mmHg +/- 17.0 and 114 +/- 11.2; no PGI2: 59 mmHg +/- 5.8 and 51 +/- 4.5; P less than 0.01 at both times), lower pulmonary vascular resistance index at 4 hr (PVRI; PGI2: 913 dynes sec cm-5m-2 +/- 91; no PGI2: 1239 +/- 68; P less than 0.05) and lower lung weight (PGI2: 76 g +/- 4; no PGI2: 146 +/- 10; P less than 0.001). Bronchoalveolar lavage studies revealed an influx of neutrophils following reperfusion that was less marked in the PGI2 group (increase in % neutrophils; PGI2: 50.4 +/- 6.7; no PGI2: 76.9 +/- 6.0; P less than 0.05). Lung injury score assessed by electron microscopy was lower in the PGI2 group (PGI2: 5.2 +/- 1.1; no PGI2; 8.1 +/- 0.5; P less than 0.05). It is concluded that PGI2 treatment is protective against ischemic lung injury in this model.

Oxygen consumption and distribution of blood flow in rats climbing a laddermill

The purpose of this study was threefold: 1) to determine whether untrained rats that refused to run on treadmill would climb on a laddermill (75 degrees incline); 2) to determine O2 consumption (VO2) in untrained rats as a function of laddermill climbing speed; and 3) to determine whether the circulatory response of untrained rats to laddermill climbing is similar to that previously reported for treadmill running at an equivalent VO2. Eighteen female Sprague-Dawley rats that would not perform on a treadmill as part of another study were used to measure VO2 as a function of laddermill speed (5-17 m/min). Data were obtained from all 18 rats; VO2 increased linearly as a function of laddermill speed (r = 0.83, y = 3.0 x + 63.2). Twenty-four female Sprague-Dawley rats that also refused to run on a treadmill were used to measure mean arterial pressure, heart rate, and blood flow distribution (with microspheres) during climbing at 5 and 10 m/min. These exercise intensities were metabolically equivalent to level treadmill running at 45 and 60 m/min (VO2 approximately 78 and 93 ml.min-1.kg-1, respectively). Of the 24 animals, 23 were willing to climb. Mean arterial pressures were higher (approximately 10%) during laddermill climbing than during equivalent treadmill running, but heart rates were the same. General blood flow distribution among muscles as a function of fiber type (with red muscles receiving higher flows) and between muscles and visceral tissues (muscle blood flow increased as a function of exercise intensity while visceral blood flows decreased) were similar to data for rats running on the level.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of prolonged glucocorticoid treatment on intracellular mechanisms involved in ACTH secretion in the rat

Two chemically characterized peptides, arginine vasopressin (AVP) and corticotrophin-releasing factor-41 (CRF-41), known to stimulate ACTH secretion by interaction with their respective specific receptors on the corticotroph, were shown to cause the accumulation of phosphate esters of inositol (IP) and adenosine 3',5'-monophosphate (cAMP) respectively when added to rat anterior pituitary fragments incubated in vitro. The former 'second messenger' response (IP production) was unaffected in tissues removed from animals treated with prednisolone in the drinking water (1035 mumol/1) for 14 days. On the other hand, the cAMP response, whilst still present, was inhibited by some 50% in tissues taken from such animals. In contrast, pituitary glands from steroid-treated rats failed to respond to challenge with a variety of substances expected to cause the release of ACTH by mimicking or provoking the production of IP or cAMP. Indeed, of the wide range of ACTH secretagogues tested, only the phospholipase A2 activator melittin was able to cause attenuated ACTH release from tissues removed from treated rats. The failure to provoke ACTH release from tissues removed from steroid-treated animals was also seen when submaximal concentrations of CRF-41 or AVP, or hypothalamic extract or 48 mmol K+/1 were used as the stimuli. The staged recovery of the ACTH secretory response and IP and cAMP accumulation in vitro following the withdrawal of prednisolone treatment was also investigated. A cAMP response that did not differ significantly from that of control tissue and a normal ACTH response to K+ and to melittin were all recovered by 3 days after withdrawal, and the response to cholera toxin showed a partial recovery. Responses to all stimuli of ACTH secretion which cause their effect by entering the corticotrophs were normal by 5 days after withdrawal, when the response to CRF-41 was still significantly, and that to AVP still slightly, reduced compared with controls. Surprisingly, restoration of the ACTH response was most delayed when the expectedly most potent extracellular stimulus (hypothalamic extract) was used. In this case, release was still significantly impaired 7 days after steroid withdrawal. The results show that the glucocorticoid acts to compromise several distinct steps in the process whereby extracellular signals such as CRF-41 and AVP cause the secretion of ACTH. The only step that appears to be spared is the generation of IP by AVP.(ABSTRACT TRUNCATED AT 400 WORDS)

A new model for assessment of lung preservation

No completely satisfactory experimental model exists to compare different techniques of preservation currently used in the distant procurement of a lung allograft. A canine model of left lung transplantation is described in which an inflatable cuff is placed around each pulmonary artery. Each cuff is connected to a subcutaneous reservoir, which allows alternate occlusion of either pulmonary artery. Functional assessment of lung function is made during ventilation of both lungs and after a 10-minute period of perfusion to the native lung alone and then to the transplanted lung alone. Systemic and pulmonary artery pressures are recorded continuously, and measurement of arterial blood gases and oxygen uptake are made immediately after the operation and again at 3 days. The animal is then put to death and the lungs are excised and weighed. Five dogs underwent transplantation of the donor lung immediately after excision (mean ischemic time = 55 +/- 7 minutes). Similar values for oxygen tension and oxygen uptake were obtained postoperatively for the right lung (oxygen tension = 420 mm Hg, oxygen uptake = 101 ml/min) and the left lung (oxygen tension = 368 mm Hg, oxygen uptake = 108 ml/min). However, carbon dioxide tension was elevated (right lung = 41 mm Hg, left lung = 52 mm Hg). Mean pulmonary artery pressure increased during allograft perfusion (right lung = 14 mm Hg, left lung = 24 mm Hg), although systemic blood pressure was unchanged. Similar results were observed at 3 days. The mean weight of the native lung was 101 +/- 2 gm and that of the transplanted lung, 128 +/- 6 gm. This model achieves consistent survival and allows serial observations of the functional adequacy of an allograft compared with a normal contralateral lung.