The common drivers of children and young people's health and wellbeing across 13 local government areas: a systems view

BACKGROUND

System dynamics approaches, including group model building (GMB) and causal loop diagrams (CLDs), can be used to document complex public health problems from a community perspective. This paper aims to apply Social Network Analysis (SNA) methods to combine multiple CLDs created by local communities into a summary CLD, to identify common drivers of the health and wellbeing of children and young people.

METHODS

Thirteen community CLDs regarding children and young people health and wellbeing were merged into one diagram involving three steps: (1) combining variable names; (2) CLD merging, where multiple CLDs were combined into one CLD with a set of unique variables and connections; (3) paring, where the Decision-Making Trial and Evaluation Laboratory (DEMATEL) method was used to generate a cut-point to reduce the number of variables and connections and to rank the overall importance of each variable in the merged CLD.

RESULTS

Combining variable names resulted in 290 variables across the 13 CLDS. A total of 1,042 causal links were identified in the merged CLD. The DEMATEL analysis of the merged CLD identified 23 common variables with a net importance between 1.0 and 4.5 R + C values and 57 causal links. The variables with the highest net importance were 'mental health' and 'social connection & support' classified as high net receivers of influence within the system.

CONCLUSIONS

Combining large CLDs into a simple diagram represents a generalisable model of the drivers of complex health problems.

Glenohumeral Instability and Arm Pain in Overhead Throwing Athletes: A Correlational Study

Background

The overhead activity of throwing a baseball is arguably the most demanding athletic endeavor placed on the glenohumeral (GH) joint. Previous studies illustrate that 75-80% of baseball players will experience some degree of upper extremity (UE) pain. GH instability is thought to play a role.

Purpose

The purpose of this study was to investigate the relationship between GH joint hypermobility and instability with measures of arm pain and performance in overhead throwing athletes.

Methods

Actively competing baseball pitchers were recruited and evaluated once with the anterior-posterior Load and Shift examination procedure, the Kerlan-Jobe Orthopedic Clinic Shoulder and Elbow Questionnaire (KJOC), and the Functional Arm Scale for Throwers (FAST). Multivariate analysis was performed to identify correlation between severe GH capsular laxity (GH instability), mild capsular laxity (GH hypermobility), no capsular laxity (GH normal), and presence of shoulder pain when pitching.

Study Design

Cross-sectional Study.

Results

Forty-five pitchers were evaluated, 62.2% of throwing shoulders were classified normal stability, 26.7% were classified hypermobile, and 11.1% were classified unstable. Average KJOC scores for pitchers with the three mobility categories were 66.1 (normal), 59.7 (hypermobile), and 45.0 (unstable). Average FAST scores among the pitchers were 19.9 (normal), 34.2 (hypermobile), and 32.2 (unstable). Pitchers with GH instability and GH hypermobility demonstrated increased arm pain compared to athletes with normal GH joints; KJOC scores of 3.2, 5.5, and 7.4 (p = 0.0007), respectively.

Conclusion

Pitchers with GH instability and hypermobility demonstrated significantly increased ratings of arm pain compared to pitchers with no capsular laxity.

Level of Evidence

3b.

Tracking implementation within a community-led whole of system approach to address childhood overweight and obesity in south west Sydney, Australia

Background

Obesity is a chronic disease that contributes to additional comorbidities including diabetes, kidney disease and several cancers. Change4Campbelltown implemented a ‘whole of system’ approach to address childhood overweight and obesity. We present methods to track implementation and stakeholder engagement in Change4Campbelltown.

Methods

Change4Campbelltown aimed to build capacity among key leaders and the broader community to apply techniques from systems thinking to develop community-led actions that address childhood obesity. Change4Campbelltown comprised development of a stakeholder-informed Causal Loop Diagram (CLD) and locally-tailored action plan, formation of key stakeholder and community working groups to prioritise and implement actions, and continuous monitoring of intervention actions. Implementation data included an action register, stakeholder engagement database and key engagement activities and were collected quarterly by the project management team over 2 years of reporting.

Results

Engagement activities increased level of community engagement amongst key leaders, the school-sector and community members. Community-led action increased as engagement increased and this action is mapped directly to the primary point of influence on the CLD. As action spread diversified across the CLD, the geographical spread of action within the community increased.

Conclusions

This paper provides a pragmatic example of the methods used to track implementation of complex interventions that are addressing childhood overweight and obesity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-11288-5.

Tools and analytic techniques to synthesise community knowledge in CBPR using computer-mediated participatory system modelling

Participatory systems thinking methods are often used in community-based participatory research to engage and respond to complexity. Participation in systems thinking activities creates opportunities for participants to gain useful insights about complexity. It is desirable to design activities that extend the benefits of this participation into communities, as these insights are predictive of success in community-based prevention. This study tests an online, computer-mediated participatory system modelling platform (STICKE) and associated methods for collating and analysing its outputs. STICKE was trialled among a group of community members to test a computer-mediated system modelling exercise. The causal diagrams resulting from the exercise were then merged, and network analysis and DEMATEL methods applied to inform the generation of a smaller summary model to communicate insights from the participant group as a whole. Participants successfully completed the online modelling activity, and created causal diagrams consistent with expectations. The DEMATEL analysis was identified as the participant-preferred method for converging individuals causal diagrams into a coherent and useful summary. STICKE is an accessible tool that enabled participants to create causal diagrams online. Methods trialled in this study provide a protocol for combining and summarising individual causal diagrams that was perceived to be useful by the participant group. STICKE supports communities to consider and respond to complex problems at a local level, which is cornerstone of sustainable effective prevention. Understanding how communities perceive their own health challenges will be important to better support and inform locally owned prevention efforts.

Comparing complex perspectives on obesity drivers: action-driven communities and evidence-oriented experts

INTRODUCTION

The Foresight obesity map represents an expert-developed systems map describing the complex drivers of obesity. Recently, community-led causal loop diagrams have been developed to support community-based obesity prevention interventions. This paper presents a quantitative comparison between the Foresight obesity systems map and a community-developed map of the drivers of obesity.

METHODS

Variables from a community-developed map were coded against the thematic clusters defined in the Foresight map to allow comparison of their sizes and strength of adjoining causal relationships. Central variables were identified using techniques from network analysis. These properties were compared to understand the similarities and differences between the systems as defined by the two groups.

RESULTS

The community map focused on environmental influences, such as built physical activity environment (18% of variables) and social psychology (38%). The Foresight map's largest cluster was physiology (23%), a minimal focus in the community map (2%). Network analysis highlighted media and available time within both maps, but variables related to school and sporting club environments were unique to the community map.

CONCLUSION

Community stakeholders focus on modifiable social and environmental drivers of obesity. Capturing local perspectives is critical when using systems maps to guide community-based obesity prevention.

Quantifying a Systems Map: Network Analysis of a Childhood Obesity Causal Loop Diagram

Causal loop diagrams developed by groups capture a shared understanding of complex problems and provide a visual tool to guide interventions. This paper explores the application of network analytic methods as a new way to gain quantitative insight into the structure of an obesity causal loop diagram to inform intervention design. Identification of the structural features of causal loop diagrams is likely to provide new insights into the emergent properties of complex systems and analysing central drivers has the potential to identify leverage points. The results found the structure of the obesity causal loop diagram to resemble commonly observed empirical networks known for efficient spread of information. Known drivers of obesity were found to be the most central variables along with others unique to obesity prevention in the community. While causal loop diagrams are often specific to single communities, the analytic methods provide means to contrast and compare multiple causal loop diagrams for complex problems.

Neurodevelopmental Outcomes Following Extensive Cardiopulmonary Resuscitation in the Delivery Room for Infants Born <29 Weeks’ Gestational Age

BACKGROUND: Neurodevelopmental outcomes of preterm infants who receive extensive CPR (ECPR), defined as chest compression with or without epinephrine in the delivery room, remain unclear.

OBJECTIVES: To compare the neurodevelopmental outcomes of preterm infants admitted to Canadian NICUs requiring ECPR versus those who did not require ECPR in the delivery room.

DESIGN/METHODS: Preterm infants born at <29 weeks GA between January 1, 2010 and September 30, 2011 and evaluated at CNFUN centers were retrospectively evaluated. The primary outcome was a composite of death or neurodevelopmental impairment (NDI) at 18-21 months CA defined as presence of any one or more of the following: definitive cerebral palsy or Bayley- III cognitive, language, motor scores <85 on any one of the components or hearing impairment or visual impairment. Demographic factors, neurodevelopmental status including Bayley III cognitive, language and motor scores and sensory impairments were compared between the ECPR and the no ECPR group using univariate and multivariate analyses. RESULTS: Of 2488 eligible infants, 197 (7.9%) received ECPR. 83% of surviving infants had follow-up data. Demographic and outcomes data are summarized below in Table 1 and 2 respectively.

Enhancing medical named entity recognition with an extended segment representation technique

OBJECTIVE

The objective of this paper is to formulate an extended segment representation (SR) technique to enhance named entity recognition (NER) in medical applications.

METHODS

An extension to the IOBES (Inside/Outside/Begin/End/Single) SR technique is formulated. In the proposed extension, a new class is assigned to words that do not belong to a named entity (NE) in one context but appear as an NE in other contexts. Ambiguity in such cases can negatively affect the results of classification-based NER techniques. Assigning a separate class to words that can potentially cause ambiguity in NER allows a classifier to detect NEs more accurately; therefore increasing classification accuracy.

RESULTS

The proposed SR technique is evaluated using the i2b2 2010 medical challenge data set with eight different classifiers. Each classifier is trained separately to extract three different medical NEs, namely treatment, problem, and test. From the three experimental results, the extended SR technique is able to improve the average F1-measure results pertaining to seven out of eight classifiers. The kNN classifier shows an average reduction of 0.18% across three experiments, while the C4.5 classifier records an average improvement of 9.33%.

A comparison of two non-thrust mobilization techniques applied to the C7 segment in patients with restricted and painful cervical rotation

OBJECTIVES

Cervical mobilization and manipulation have been shown to improve cervical range of motion and pain. Rotatory thrust manipulation applied to the lower cervical segments is associated with controversy and the potential for eliciting adverse reactions (AR). The purpose of this clinical trial was to describe two translatory non-thrust mobilization techniques and evaluate their effect on cervical pain, motion restriction, and whether any adverse effects were reported when applied to the C7 segment.

METHODS

This trial included 30 participants with painful and restricted cervical rotation. Participants were randomly assigned to receive one of the two mobilization techniques. Active cervical rotation and pain intensity measurements were recorded pre- and post-intervention. Within group comparisons were determined using the Wilcoxon signed-rank test and between group comparisons were analyzed using the Mann-Whitney U test. Significance was set at P = 0.05.

RESULTS

Thirty participants were evaluated immediately after one of the two mobilization techniques was applied. There was a statistically significant difference (improvement) for active cervical rotation after application of the C7 facet distraction technique for both right (P = 0.022) and left (P = 0.022) rotation. Statistically significant improvement was also found for the C7 facet gliding technique for both right (P = 0.022) and left rotation (P = 0.020). Pain reduction was statistically significant for both right and left rotation after application of both techniques. Both mobilization techniques produced similar positive effects and one was not statistically superior to the other.

DISCUSSION

A single application of both C7 mobilization techniques improved active cervical rotation, reduced perceived pain, and did not produce any AR in 30 patients with neck pain and movement limitation. These two non-thrust techniques may offer clinicians an additional safe and effective manual intervention for patients with limited and painful cervical rotation. A more robust experimental design is recommended to further examine these and similar cervical translatory mobilization techniques.

Ultrasound analysis of the vertebral artery during non-thrust cervical translatoric spinal manipulation

OBJECTIVE

Cervical translatoric spinal manipulation (TSM) techniques have been suggested as a safer alternative to cervical thrust rotatory techniques. The objective of this study was to determine the effect of three C5-C6 non-thrust TSM techniques on vertebral artery (VA) lumen diameter (LD) and two blood flow velocity parameters. The two-tailed research hypothesis was that the TSM techniques would result in a significant change (increase or decrease) in blood flow velocity and arterial LD at the C5-C6 intertransverse portion of the VA.

METHODS

In a sample of 30 subjects representative of a clinical population, color-coded duplex Doppler diagnostic ultrasound imaging was used to collect data on LD, peak systolic velocity (PSV), and end diastolic velocity with the cervical spine positioned in neutral and in three different manipulation positions. Pair-wise mean differences between measurements at baseline (neutral position) and in all three manipulation positions were analyzed using two-tailed paired t-tests with alpha set at 0·05.

RESULTS

Of the 18 paired comparisons, there were four statistically significant differences between measurements in the neutral position and a manipulation position, three concerning LD and one PSV.

DISCUSSION

The three significant differences in LD ranged from 4·6 to 3·2% and were not associated with changes in blood flow velocity. The one significant change in PSV was only 6·6 cm/s. A value that still greatly exceeded the end diastolic velocity. No subject experienced symptoms associated with VA compromise. This study has provided evidence for the safety of the three lower cervical non-thrust TSM techniques on the current population studied. Further study is required on thrust versus non-thrust TSM techniques and on levels other than C5-C6.

Comprehensive review of neural network-based prediction intervals and new advances

This paper evaluates the four leading techniques proposed in the literature for construction of prediction intervals (PIs) for neural network point forecasts. The delta, Bayesian, bootstrap, and mean-variance estimation (MVE) methods are reviewed and their performance for generating high-quality PIs is compared. PI-based measures are proposed and applied for the objective and quantitative assessment of each method's performance. A selection of 12 synthetic and real-world case studies is used to examine each method's performance for PI construction. The comparison is performed on the basis of the quality of generated PIs, the repeatability of the results, the computational requirements and the PIs variability with regard to the data uncertainty. The obtained results in this paper indicate that: 1) the delta and Bayesian methods are the best in terms of quality and repeatability, and 2) the MVE and bootstrap methods are the best in terms of low computational load and the width variability of PIs. This paper also introduces the concept of combinations of PIs, and proposes a new method for generating combined PIs using the traditional PIs. Genetic algorithm is applied for adjusting the combiner parameters through minimization of a PI-based cost function subject to two sets of restrictions. It is shown that the quality of PIs produced by the combiners is dramatically better than the quality of PIs obtained from each individual method.

Use of anterior tibial translation in the management of patellofemoral pain syndrome in older patients: a case series

The currently most plausible pathophysiologic theory for the etiology of pain in patients with patellofemoral pain syndrome involves abnormal mechanical stress to the patellofemoral joint. At this time, there is no consensus nor is there a sufficient body of research evidence to guide management of patients with patellofemoral pain syndrome. This means that clinicians have to rely to some extent on a mechanism-based approach. Decreased quadriceps flexibility and muscular endurance have been identified as possibly relevant impairments in patients with patellofemoral pain syndrome. Surgical anterior translation of the tibial tuberosity with the Maquet procedure has a proven positive effect on patellofemoral contact forces. This case series studied the effects of a physical therapy management approach that included translating the tibia anteriorly while performing open kinetic chain quadriceps training and manual muscle stretching of the rectus femoris muscle. Outcome measures used included the numeric pain rating scale and goniometric measurement of rectus femoris muscle length in a standardized test position. Anterior tibial translation reduced pain during both interventions and also produced clinically and statistically significant pre- to post-intervention improvements in pain during manual muscle testing and rectus femoris length testing in addition to statistically significant pre- to post-intervention increases in rectus femoris muscle length. The results of this quasi-experimental study indicate the need for future experimental study. Future study should include functional in addition to impairment-based outcome measures, standardization and blinding for the rectus femoris muscle length test (should future researchers chose to again use this outcome measure), a pilot study establishing reliability of outcome measures collected by the therapist, younger subjects, and the collection of longer-term outcome data.

The immediate effects of upper thoracic translatoric spinal manipulation on cervical pain and range of motion: a randomized clinical trial

This study examined the effect of translatoric spinal manipulation (TSM) on cervical pain and cervical active motion restriction when applied to upper thoracic (T1-T4) segments. Active cervical rotation range of motion was measured re- and post-intervention with a cervical inclinometer (CROM), and cervical pain status was monitored before and after manipulation with a Faces Pain Scale. Study participants included a sample of convenience that included 32 patients referred to physical therapy with complaints of pain in the mid-cervical region and restricted active cervical rotation. Twenty-two patients were randomly assigned to the experimental group and ten were assigned to the control group. Pre- and post-intervention cervical range of motion and pain scale measurements were taken by a physical therapist assistant who was blinded to group assignment. The experimental group received TSM to hypomobile upper thoracic segments. The control group received no intervention. Paired t-tests were used to analyze within-group changes in cervical rotation and pain, and a 2-way repeated-measure ANOVA was used to analyze between-group differences in cervical rotation and pain. Significance was accepted at p = 0.05. Significant changes that exceeded the MDC(95) were detected for cervical rotation both within group and between groups with the TSM group demonstrating increased mean (SD) in right rotation of 8.23 degrees (7.41 degrees ) and left rotation of 7.09 degrees (5.83 degrees ). Pain levels perceived during post-intervention cervical rotation showed significant improvement during right rotation for patients experiencing pain during bilateral rotation only (p=.05). This study supports the hypothesis that spinal manipulation applied to the upper thoracic spine (T1-T4 motion segments) significantly increases cervical rotation ROM and may reduce cervical pain at end range rotation for patients experiencing pain during bilateral cervical rotation.

The effect of tibio-femoral traction mobilization on passive knee flexion motion impairment and pain: a case series

The purpose of this case series was to explore the effects of tibio-femoral (TF) manual traction on pain and passive range of motion (PROM) in individuals with unilateral motion impairment and pain in knee flexion. Thirteen participants volunteered for the study. All participants received 6 minutes of TF traction mobilization applied at end-range passive knee flexion. PROM measurements were taken before the intervention and after 2, 4, and 6 minutes of TF joint traction. Pain was measured using a visual analog scale with the TF joint at rest, at end-range passive knee flexion, during the application of joint traction, and immediately post-treatment. There were significant differences in PROM after 2 and 4 minutes of traction, with no significance noted after 4 minutes. A significant change in knee flexion of 25.9°, which exceeded the MDC(95,) was found when comparing PROM measurements pre- to final intervention. While pain did not change significantly over time, pain levels did change significantly during each treatment session. Pain significantly increased when the participant's knee was passively flexed to end range; it was reduced, although not significantly, during traction mobilization; and it significantly decreased following traction. This case series supports TF joint traction as a means of stretching shortened articular and periarticular tissues without increasing reported levels of pain during or after treatment. In addition, this is the first study documenting the temporal aspects of treatment effectiveness in motion restoration.

Effect of 10%, 30%, and 60% body weight traction on the straight leg raise test of symptomatic patients with low back pain

STUDY DESIGN

Single group test-retest repeated measures.

OBJECTIVES

To determine the effects of lumbar traction with 3 different amounts of force (10%, 30% and 60% body weight) on pain-free mobility of the lower extremity as measured by the straight leg raise (SLR) test.

BACKGROUND

There are several recommendations on how lumbar traction should be performed, but the duration, frequency, force, and type of technique to be applied differ among the sources.

METHODS AND MEASURES

Ten subjects with subjective complaints of low back pain or radicular symptoms with a positive unilateral SLR test below 45 degrees participated in this study. The pain-free mobility of the lower extremity in the SLR test position was measured prior to and immediately following 5 minutes of static traction in the supine position. Random assignment in the order of the amount of applied traction was implemented.

RESULTS

The straight leg raise measurements were found to be significantly greater immediately following 30% and 60% of body weight traction as compared to pretraction and 10% of body weight traction. The mean (SD) SLR measurements were pretraction (24.1 degrees +/- 13.0), 10% of body weight traction (27.4 degrees +/- 14.5), 30% of body weight traction (34.0 degrees +/- 14.3), 60% of body weight traction (36.5 degrees +/- 15.8).

CONCLUSIONS

The results of this study indicate that traction in this group of patients improved the mobility of the lower extremity during the SLR test. Both 30% and 60% of body weight tractions were shown to be effective for increasing motion beyond pretraction levels.

Maillard reactions in lens proteins: methylglyoxal-mediated modifications in the rat lens

The nonenzymatic Maillard reaction is thought to contribute to aging and cataract formation in the lens. As levels of methylglyoxal (MG) and glutathione (GSH) affect the reaction, we examined the relationship of these factors and determined the effect of a glyoxalase I inhibitor on the Maillard reaction. Rat lens cultures were maintained for up to 3 days in TC-199 medium with or without 20 m m glyceraldehyde (GLD) and 250 microm S-[N-hydroxy-N-(4-chlorophenyl) carbamoyl] glutathione diethyl ester (HCCG diester). We measured GSH, MG, D-lactate, glyoxalase I activity, immunoreactive MG-derived advanced glycation endproducts (MG-AGEs) and imidazolysine in organ cultured rat lenses. In vitro experiments with isolated rat lens proteins revealed that HCCG alone inhibited glyoxalase I activity in a dose-dependent manner. In organ cultured rat lens protein, GLD increased MG levels 24-fold, and the addition of HCCG diester further increased it by about two-fold. GSH levels fell sharply in the presence of GLD and this was prevented to some extent by the presence of HCCG diester. D-lactate production in the lens was suppressed by HCCG diester treatment. Dialysed lens proteins retained glyoxalase I activity, indicating that the enzyme was unaltered during incubation. MG-AGEs and imidazolysine levels were significantly higher (P<0.05) in GLD-treated lenses, but a combination of HCCG diester and GLD lowered immunoreactive MG-AGEs and imidazolysine levels compared to GLD alone. HCCG had no significant effect on MG-AGE formation in lens proteins incubated with GLD or MG. We conclude that exogenous GLD enhances MG and MG-AGE levels in the rat lens and that this increase is accompanied by a loss in GSH. In addition, inhibition of glyoxalase I promotes MG accumulation.

Endothelial cell adaptation to chronic thrombosis

BACKGROUND

The autogenous vein graft has proven to be the most durable conduit in lower extremity vascular bypass grafts. Failures due to thrombosis, intimal hyperplasia, and progression of atherosclerotic disease commonly plague the vascular surgeon. Part of the ability of vein grafts to provide a nonthrombogenic surface relies on the capability of the endothelial cell to produce prostacyclin, a potent vasodilator and inhibitor of platelet aggregation. Once a graft fails and thromboses, little is known as to the effects of the thrombus on the function and morphology of endothelial cells. Earlier studies by this laboratory demonstrated the ability of arterialized canine vein grafts to recover function after 5 days of exposure to thrombus. This investigation sought to explore the limits of endothelial cell viability and recovery to extended periods of thrombosis.

METHODS

Using a canine model of arterialized vein grafts, prostacyclin production (measured as 6-keto-PGF1a) was assessed in an ex vivo perfusion system from grafts exposed to thrombus for 10 days (group I) and 20 days (group II). Both groups underwent thrombectomy and a recovery period of 30 days. The grafts were perfused with Hanks' balanced salt solution and samples were obtained at 5 and 30 minutes to determine prostacyclin levels. Arachidonic acid was then added to a new perfusate of Hanks' solution and samples were again obtained at 5 and 30 minutes. Results were expressed as PGF/graft area (cm2/min). Representative samples of each graft underwent scanning electron microscopy.

RESULTS

Without arachidonic acid, prostacyclin production of group II (20 day) grafts was greater than group I (10 day) grafts at 5 minutes of perfusion (4.31 versus 2.42, P = 0.08) and at 30 minutes (1.86 versus 0.95, P = 0.02). In response to the addition of arachidonic acid both groups increased prostacyclin production (group I, P = 0.004; group II, P = 0.12). A comparison was made between prostacyclin production at baseline and after addition of arachidonic acid. Group I grafts demonstrated a greater percent increase in prostacyclin production compared to group II (385% versus 229%, P = 0.01). Scanning electron microscopy showed no differences in endothelial coverage between the study groups.

CONCLUSIONS

These results demonstrate that although endothelial cells are able to recover a basal level of prostacyclin production, the response to substrate stimulation diminishes with increased exposure time to thrombus. This diminished response may be important in understanding the ability of vein grafts to survive after a period of thrombosis.

The effect of thrombus on the vascular endothelium of arterialized vein grafts

BACKGROUND

It is known that vein grafts can be salvaged by clot removal, but patency rates are diminished. This study was designed to determine the effects of thrombus on vascular endothelium and the ability of the endothelium to recover normal function.

METHODS

Thirty external jugular vein grafts were placed as bilateral femoral artery interposition grafts in 15 mongrel dogs and allowed to arterialize for a period of at least 12 weeks. Six control grafts were not exposed to thrombus (C-NT). Six other control grafts were exposed to thrombus for 7 days and removed, ie, allowed no in vivo recovery (C-T). The remaining 18 grafts in 9 canines were exposed to autologous thrombus for 5 days and then flow was restored. The right femoral graft was removed 7 days after thrombectomy and the left removed 30 days after thrombectomy. At the time of removal, the grafts were perfused with a balanced salt solution alone and then with arachidonic acid added to the same volume of the salt solution. Perfusates were collected at 5, 15, and 30 minutes. These perfusates were assayed for the presence of 6-keto-prosglandin F1 alpha (6-keto-PGF1(1 alpha)), a metabolite of prostacyclin (PGI2). Over the 30-day recovery period, the amounts of 6-keto-PGF1(1 alpha) produced with and without arachidonic acid added were compared to assess endothelial response. Electron micrographs of the endothelium of all vein grafts were compared to the assay findings.

RESULTS

When arachidonic acid was added to the perfusion system, there was a several fold increase in the production of 6-keto-PGF1(1 alpha) over baseline in all grafts allowed recovery. Grafts (C-T) that were allowed no in vivo recovery had no response to arachidonic acid. Ratios of 6-keto-PGF1(1 alpha) production with arachidonic acid stimulation to 6-keto-PGF1(1 alpha) production without stimulation were calculated to compare endothelial function. The electron micrographs showed the vascular endothelium to be severely injured after contact with thrombus, but recovered by 7 days.

CONCLUSIONS

This study suggests that the endothelium of canine vein grafts is injured by contact with thrombus for 5 days but can recover structure and function. This recovery is detectable at 7 days post-thrombectomy.

Flurbiprofen (Ansaid) cross-sensitivity in an aspirin-sensitive asthmatic patient

Flurbiprofen (Ansaid) is a newly released nonsteroidal antiinflammatory drug (NSAID) that is a potent inhibitor of prostaglandin synthesis. We report the first case (to our knowledge) of a flurbiprofen-induced asthmatic reaction confirmed by single-blind oral challenges. Cross-sensitivity and cross-desensitization between aspirin (ASA) and flurbiprofen were also demonstrated in this patient with rhinosinusitis and asthma, thus reinforcing the observation that NSAIDs capable of cyclooxygenase inhibition crossreact with ASA in producing characteristic respiratory reactions.

Treatment of acute vascular occlusions with intra-arterial urokinase

This study reviewed 57 patients with 71 vascular occlusions treated with urokinase from 1985 to 1988. Of these patients, 89% were candidates for urgent surgery. Total clot lysis was achieved in 73% of cases. The success rate rose with increasing experience (p less than 0.05), and recent occlusions had more favorable outcomes than older ones (p less than 0.05). The length and type of occluded conduit (graft or vessel), age, sex, other medical conditions, and concurrent use of heparin had no influence on success. Of 18 cases successfully lysed and not subjected to any adjunctive therapy directed at the cause of occlusion, 9 (50%) reoccluded within 1 to 88 days (mean: 25 days). Cases successfully treated with thrombolysis and surgery or dilation of the causative stenosis had poor 1-year patencies: 17%, 20%, and 55% for vein grafts, prosthetic grafts, and native arteries, respectively. With additional urokinase treatments, surgical operations, and percutaneous procedures, 1-year patencies were 22%, 45%, and 65%, respectively.

Home oxygen therapy. Outcome of infants discharged from NICU on continuous treatment

Forty-four oxygen-dependent infants were discharged home in oxygen from an NICU during an 8-year period. Survivors were followed for 3 years. The infants' discharge diagnoses were bronchopulmonary dysplasia (BPD) (39), sleep apnea (2), and congenital cardiac defects (3). The five infants who had diagnoses other than BPD all died, but 34 of 39 infants with BPD survived. Supplemental oxygen was discontinued at a mean age of 13.4 months. The infants with BPD experienced health, growth, nutritional, neurodevelopmental and sensory problems that necessitated frequent rehospitalizations and utilization of a variety of medical and support services.

Alprazolam reduces stress-induced mortality in cardiomyopathic hamsters

These experiments examined the role of several variables involved in the production of serious, stress-induced disease. Experiments 1 and 2 indicated that stress may not be medically dangerous except in animals with a predisposition or vulnerability to disease. Repeated exposure to cold-immobilization produced no detectable ill effects in healthy hamsters, but it was lethal for cardiomyopathic hamsters (CMHs). Experiment 3 showed that stressor intensity was also critical to the outcome of stress. CMHs succumbed when they were stressed in the supine position, but not when they were immobilized in the less stressful prone position. In Experiment 4, we attempted to reduce the stressfulness of cold-immobilization with the anxiolytic alprazolam. Alprazolam effectively blocked stress-induced mortality. In addition, we found that poststress body temperature was a crude predictor of an animal's ability to cope with stress. Alprazolam prevented CMHs from developing stress-induced hypothermia.

Aging, stress, and chronic disease interact to suppress plasma testosterone in Syrian hamsters

The effects of old age, chronic disease, and stress on testicular function were examined in Syrian hamsters living on a 12-hr photoperiod. Plasma testosterone concentrations and testes weights were maintained in healthy hamsters 16-19 months of age, but chronic stress decreased plasma testosterone in these old hamsters and not in younger ones (8-11 months of age). Chronic disease in the form of congestive heart failure (CHF) in cardiomyopathic hamsters also decreased plasma testosterone and testes weights, although it is not clear what aspects of this disease affected testicular function. There was an interaction between disease and stress, in that chronic stress produced lower plasma testosterone and testes weights in hamsters with heart failure than in age-matched stressed, healthy hamsters. It appears that younger hamsters can maintain reproductive function during stress, but older ones may not be able to do so. Congestive heart failure in hamsters clearly impairs normal reproductive function by itself; it also makes them more susceptible to stress, so that combining stress and disease results in almost complete suppression of plasma testosterone levels.

Adrenal hormonal indices of stress in laboratory rats

When individual rats were exposed to different intensities of a stressor, foot shock, plasma catecholamines were found to be sensitive and reliable indices of the stress. Plasma corticosterone did not perform as well. Similarly, levels of both plasma epinephrine and norepinephrine correlated highly significantly with a behavioral measure of the degree of stress--namely, the amount of movement about the cage seen during the 30 sec shock period. Importantly, this behavioral measure was as sensitive and reliable an index of stress as the catecholamines. However, use of either the catecholamines or this behavioral measure as a clinically useful measure of the level of stress was limited by the fact that their responses to the stressor were extremely short-lived. Nonetheless, because the catecholamines reliably and sensitively track the intensity of a stressor, they appear to be a good visceral measure of stress, perhaps the best currently available. But the behavioral concomitants of stress are quickly and easily quantifiable and present a wide range to study, starting with alerting, through a progression of more aroused motor activity, and ending with fight-flight. Because the behavioral concomitants of stress have not been as intensively studied as the endocrine ones, we believe that future efforts to find a clinically useful index of stress will be rewarded by a refocussing of attention away from the visceral respondent to the overt behavioral one.

An analysis of some sensitizing agents in the pathogenesis of stress-induced gastric erosive disease

Prior surgical implantation of a venous catheter sensitized rats to cold-immobilization stress. Three of six catheterized females succumbed during the stress. The remaining rats fell into two groups in terms of their core temperature at the end of the stress period: Male uncatheterized rats had higher temperatures than rats in the other three groups. No relation was found between catheter patency and magnitude of hypothermia. Degree of gastric disease paralleled the core temperature findings in that the male uncatheterized rats had significantly fewer gastric erosions than the rats in the other three groups. Additionally, a robust effect of gender was found with uncatheterized females showing more hypothermia and more gastric disease than uncatheterized males. A subsequent experiment was conducted to evaluate whether anesthesia or wearing the protective spring was responsible in part for the sensitization seen. Here, the gender difference was less although females consistently averaged lower core temperatures after stress than did males. Despite similar core temperatures after stress, females that were prepared with the protective spring apparatus developed more gastric disease than female controls or similarly treated males. Thus, the additional sensitization exhibited by females in the first experiment may relate to the fact that both catheterization and the taping procedure were sensitizers while only catheterization was a sensitizer for males.

Roles of stress and adaptation in the elicitation of face-immersion bradycardia

Thirteen young healthy human volunteers immersed their faces in warm or cold water on one day while breathing through a snorkel and on another day while breath holding. The magnitude of the elicited bradycardia was most prominently due to water temperature, with apnea playing a less important role. Perceived stress could affect the magnitude of the response, but it was less important than the other variables. Thus statistically significant nonparametric correlations were found for the group but not for most individuals between a scoring technique that assessed perceived stress and heart rate. In contrast to animals, these data indicate that bradycardia may be reliably elicited in humans by face immersion in cold water and that stress is neither necessary nor sufficient to produce this phenomenon. Adaptation did not seem to play a role in the development of this physiological response.