Methods and problems in the measurement of body water and electrolyte pools with radionuclide tracers

With the possible exception of ECF, body electrolyte spaces and pools can be measured with fair accuracy and are useful in their proper experimental context. The use of improved tracer techniques and mathematical analysis to study transfer rates between pools and the physiological factors which influence these rates offer a promising means of further progress in this field.

Organisational careers versus boundaryless careers: Insights from the accounting profession

Much of careers research in recent times has focused on the so called move away from traditional ‘organisational careers’ to what Arthur (1994) coined the ‘boundaryless career’. This paper discusses research that challenges the applicability of the boundaryless career and the claim that ‘organisational careers are dead’. Drawing on interviews with nearly 60 accountants in Australia, the research demonstrates that employees are pursuing an organisational career. For this occupational group, the lack of proactive HR involvement in career development and the emphasis on self-direction was not appreciated. Rather, the research highlighted that the lack of organisational career management had negative implications for employee attitudes and motivation. The issues raised by the participants suggest it is timely to consider whether the unique characteristics of the accounting profession represent an ideal environment for the maintenance of an ‘organisational career’.

Distributed expertise: qualitative study of a British network of multidisciplinary teams supporting parents of children with chronic kidney disease

BACKGROUND

Long-term childhood conditions are often managed by hospital-based multidisciplinary teams (MDTs) of professionals with discipline specific expertise of a condition, in partnership with parents. However, little evidence exists on professional-parent interactions in this context. An exploration of professionals' accounts of the way they individually and collectively teach parents to manage their child's clinical care at home is, therefore, important for meeting parents' needs, informing policy and educating novice professionals. Using chronic kidney disease as an exemplar this paper reports on one aspect of a study of interactions between professionals and parents in a network of 12 children's kidney units in Britain.

METHODS

We conducted semi-structured, qualitative interviews with a convenience sample of 112 professionals (clinical-psychologists, dietitians, doctors, nurses, pharmacists, play-workers, therapists and social workers), exploring accounts of their parent-educative activity. We analysed data using framework and the concept of distributed expertise.

RESULTS

Four themes emerged that related to the way expertise was distributed within and across teams: (i) recognizing each other's' expertise, (ii) sharing expertise within the MDT, (iii) language interpretation, and (iv) acting as brokers. Two different professional identifications were also seen to co-exist within MDTs, with participants using the term 'we' both as the intra-professional 'we' (relating to the professional identity) when describing expertise within a disciplinary group (for example: 'As dietitians we aim to give tailored advice to optimize children's growth'), and the inter-professional 'we' (a 'team-identification'), when discussing expertise within the team (for example: 'We work as a team and make sure we're all happy with every aspect of their training before they go home').

CONCLUSIONS

This study highlights the dual identifications implicit in 'being professional' in this context (to the team and to one's profession) as well as the unique role that each member of a team contributes to children's care. Our methodology and results have the potential to be transferred to teams managing other conditions.

Should a 31/62-day target be applicable to urinary stone patients with indwelling stents?

Objective:

Patients with urinary stone disease languish on waiting lists. They are often young and suffer morbidity and unemployment. Stone disease leads to sepsis, loss of renal units and even death. We aimed to assess the readmission rates and associated morbidity for patients with ureteric stents in situ secondary to stone disease.

Patients and methods:

Over 12 months 692 patients totalling 1114 admissions were admitted to our unit with a coded diagnosis of renal colic. Of the 692 individuals, 378 first presented as an emergency. The rest had elective first admissions.

Results:

Of the 378 emergency presentations, 78 were admitted between two and eight times. The total number of admissions for this group of 78 patients was 248. The average time interval was calculated from first emergency presentation to date of first elective treatment (52.3 days (range 2–281)) and from date of first emergency presentation to date of last treatment (63.6 days (range 2–281)). A total of 401 working days were lost.

Conclusion:

The management of patients with urinary stone disease needs serious reconsideration. We propose that patients with indwelling stents have a 31/62-day target similar to cancer patients due to the increased morbidity associated with loss of working days and the increased cost of readmissions to an overburdened health service.

Validation of the NANA (Novel Assessment of Nutrition and Ageing) touch screen system for use at home by older adults

Prospective measurement of nutrition, cognition, and physical activity in later life would facilitate early detection of detrimental change and early intervention but is hard to achieve in community settings. Technology can simplify the task and facilitate daily data collection. The Novel Assessment of Nutrition and Ageing (NANA) toolkit was developed to provide a holistic picture of an individual's function including diet, cognition and activity levels. This study aimed to validate the NANA toolkit for data collection in the community. Forty participants aged 65 years and over trialled the NANA toolkit in their homes for three 7-day periods at four-week intervals. Data collected using the NANA toolkit were compared with standard measures of diet (four-day food diary), cognitive ability (processing speed) and physical activity (self-report). Bland-Altman analysis of dietary intake (energy, carbohydrates, protein fat) found a good relationship with the food diary and cognitive processing speed and physical activity (hours) were significantly correlated with their standard counterparts. The NANA toolkit enables daily reporting of data that would otherwise be collected sporadically while reducing demands on participants; older adults can complete the daily reporting at home without a researcher being present; and it enables prospective investigation of several domains at once.

Blood volumes in cardiac surgery with cardiopulmonary bypass

PURPOSE

Total blood volume (TBV) estimation potentially impacts various aspects of cardiac surgical care, including pharmacological and transfusion interventions, hemodynamic and volume management and perfusion equipment selection. TBV is commonly computed during cardiopulmonary bypass (CPB), using standardized formulae. We hypothesized that these equations fail to accurately predict individual blood volume variability. The aim of this study was to determine TBV with a dilution technique and compare the results to commonly utilized TBV calculations.

METHODS

After institutional review board approval, data was prospectively collected and analyzed for 101 patients undergoing open-heart surgery. Hematocrits (Hct) just prior to and immediately after the initiation of CPB were used to calculate the TBV. Results were compared to (1) the Allen formula and (2) weight-based standards (70 ml/kg for males (SM); 65 ml/kg for females (SF)).

RESULTS

The average dilution TBV (male: 4684 ± 1641 ml; female: 3027 ± 1067 ml; total: 4175 ± 1617 ml) was significantly smaller (p<0.05) than TBV estimated by Allen's formula (male: 6328 ± 973 ml; female: 4167 ± 643 ml; total: 5665 ± 1134 ml) and weight-based standards (male: 6278 ± 1256 ml; female: 4924 ± 1064 ml; total: 5862 ± 1350 ml). Allen's formula and the weight-based standards correlated strongly (R(2) = 0.821, p<0.001), suggesting similar estimates of TBV when using these methods. In contrast, hemodilution correlated poorly with the estimates by Allen (R(2) = 0.221, p<0.001) and weight-based formulae (R(2) = 0.122, p<0.001), suggesting different TBV computation.

CONCLUSIONS

The dilution method during CPB for TBV estimation is applicable and reproducible in the cardiac surgical arena and can be utilized to calculate TBV. Our results suggest that traditional TBV assessment in cardiac surgical patients by Allen's and weight-based formulae lacks the desired accuracy in estimating true TBV.

Blood volume measurement by hemodilution: association with valve disease and re-evaluation of the Allen Formula

BACKGROUND

Total blood volume (TBV) assessment is central to the management of cardiac surgical patients with cardiopulmonary bypass (CPB). The widely accepted Allen Formula lacks accuracy in estimating TBV in these patients. Moreover, the impact of commonly encountered cardiac disease states on TBV has not been systematically investigated. The aim of this study was to determine TBV by hemodilution (TBVHD) for patients with valve disease, compare TBVHD to algorithms frequently used during cardiac surgery and to modify the Allen Formula to better fit today's patient population.

METHODS

TBVHD was prospectively measured upon initiation of CPB. Ninety-six patients were grouped into 4 cohorts by preoperative diagnosis and compared to Allen and weight-based formulae in a univariate analysis: mitral regurgitation (MR), coronary artery disease requiring bypass surgery (CABG) and aortic stenosis (AS) ± CABG. The independent effects of height and weight on TBV were correlated to the original Allen Formula by multiple linear regression.

RESULTS

Patients with MR had significantly larger TBVHD compared to patients with AS, CABG or both. The smallest TBVHD was found in the patients with AS and CABG. The modified Allen Formula had an excellent model fit (R(2) = 0.88 and R(2) = 0.95 for males and females, respectively; p<0.001) while the classic formula overestimated TBV by 30% in males and females. For males, height impacted TBV calculations the most whereas weight was the predominant determinant in females.

CONCLUSION

Blood volume assessment via the Allen Formula or bodyweight overestimated TBV in cardiac surgical patients, with potential implications on their management. The assumption that MR frequently presents with increased intravascular volume was confirmed whereas AS patients with coronary disease had a relatively smaller TBV. Lastly, a modified Allen Formula to better reflect today's patient population was derived to reproducibly improve accuracy in mathematical estimates of TBV.

[Arthroscopic posterior shoulder stabilization with an iliac bone graft and capsular repair]

OBJECTIVE

Arthroscopic posterior shoulder stabilization with an iliac bone graft and capsulolabral repair, which should combine the pre-existing open procedure with the advantages of improved arthroscopic visualization.

INDICATIONS

Posterior instability with concomitant pathologies (e.g. capsular insufficiency, posterior Bankart lesion, posterior glenoid dysplasia) and recurrent posterior instability after failed soft tissue reconstruction.

CONTRAINDICATIONS

Instability osteoarthritis, locked posterior shoulder dislocation, large reverse Hill-Sachs lesion, extended posterior defect of the glenoid.

SURGICAL TECHNIQUE

After arthroscopic evaluation of the shoulder joint and treatment of concomitant pathologies, a tricortical bone graft is harvested from the iliac crest. The posterior capsule is arthroscopically detached from the labrum and the posterior deltoid and rotator cuff are split in line of the muscle fibers. Then the bone graft is positioned and fixed to the posterior scapular neck as an extension of the articular glenoid surface. Thereafter, capsular reconstruction is performed after insertion of suture anchors in the posterior glenoid rim.

POSTOPERATIVE MANAGEMENT

During the first 6 weeks 60° of abduction and flexion are permitted without any rotation and full range of motion is developed gradually. Internal rotation is allowed after 8 weeks and return to sports after 12 weeks.

RESULTS

For posterior shoulder instability 13 of these operations were performed in our hospital since 2011. Until now, no recurrent instability was observed. After remodelling of the graft, one patient complained about posterior soft tissue irritation so the screws were removed.

ICDs at higher age and clinical risk factors

BACKGROUND

The implantable cardioverter defibrillator (ICD) is effective in preventing sudden cardiac death. However, in elderly patients (aged 75 years or older) the role of ICDs is still not well-defined and controversial.

METHODS

We retrospectively analysed all clinical and survival data of all ICD patients who were ≥75 years at the date of implantation in the Erasmus MC, Rotterdam, the Netherlands and the University Hospital, Basel, Switzerland. Kaplan-Meier survival analysis was performed, and mortality predictors were identified. Mortality of the cohort was compared with a random sample of patients aged 60-70 years originating from the same database and to an age- and sex-matched cohort of Dutch persons.

RESULTS

The study cohort consisted of 179 patients aged 75 years or older who were implanted between February 1999 and July 2008. The median follow-up time was 2.0 (IQR 2.8) years. Survival rates after 1, 2 and 3 years were 87, 82, 75 %, respectively. Survival was similar for primary and secondary prevention. Mortality in this study population could be predicted by combining four clinical risk factors: QRS duration >120 ms, NYHA class > II, renal failure and atrial fibrillation (AF). Survival was worse compared with the group of ICD patients aged 60-70 years and to the age- and sex-matched group of elderly persons. However, survival was not significantly worse when comparing elderly ICD patients without additional risk factors to the general population.

CONCLUSIONS

Elderly patients still have an acceptable survival probability independent of prevention indication, certainly if there are no additional clinical risk factors. The presence or absence of additional clinical risk factors should be taken into account when making the decision for implantation, since they strongly correlate with survival.

[Stability versus mobility of the shoulder. Biomechanical aspects in athletes]

The demand profile of athletes shoulders is high. On the one hand the shoulder has to provide a maximum active range of motion that allows rapid movements of the arm and on the other hand it has to be sufficiently stabilized to decelerate rapid movements and to neutralize the resulting translational forces. Two general types of instability can be differentiated in athletes shoulders: the macroinstability typically occurring in athletes involved in contact sports and the microinstability occurring in athletes involved in overhead sports.Repetitive abduction and external rotation movements of athletes involved in overhead sports lead to adaptation of the glenohumeral joint capsule and ligaments. The anterior capsule becomes stretched while the posterior capsule develops tightness. These adaptations can result in an anterior microinstability as well as posterosuperior impingement (PSI) which implicates a pathological contact of the posterosuperior rotator cuff with the posterior glenoid and which is also associated with SLAP lesions. In contrast the shoulders of swimmers are prone to anterosuperior impingement because the arm stroke involves a forceful combined anteflexion, adduction and internal rotation of the arm.The macroinstability of contact athletes is caused by sufficient trauma and characterized by a structural lesion of capsulolabral or bony lesion. While the empirical recurrence risk of young contact athletes is already high, it can be further impaired by bony defects of the glenoid. In suspected cases, critical glenoid defects should be quantified by computed tomography (CT) scans and treated by bony augmentation of the glenoid.

Stem cells for brain repair in neonatal hypoxia-ischemia

Neonatal hypoxic-ischemic insults are a significant cause of pediatric encephalopathy, developmental delays, and spastic cerebral palsy. Although the developing brain's plasticity allows for remarkable self-repair, severe disruption of normal myelination and cortical development upon neonatal brain injury are likely to generate life-persisting sensory-motor and cognitive deficits in the growing child. Currently, no treatments are available that can address the long-term consequences. Thus, regenerative medicine appears as a promising avenue to help restore normal developmental processes in affected infants. Stem cell therapy has proven effective in promoting functional recovery in animal models of neonatal hypoxic-ischemic injury and therefore represents a hopeful therapy for this unmet medical condition. Neural stem cells derived from pluripotent stem cells or fetal tissues as well as umbilical cord blood and mesenchymal stem cells have all shown initial success in improving functional outcomes. However, much still remains to be understood about how those stem cells can safely be administered to infants and what their repair mechanisms in the brain are. In this review, we discuss updated research into pathophysiological mechanisms of neonatal brain injury, the types of stem cell therapies currently being tested in this context, and the potential mechanisms through which exogenous stem cells might interact with and influence the developing brain.

Oedema is associated with clinical outcome following emergency abdominal surgery

INTRODUCTION

Oedema is observed frequently following surgery and may be associated with worse outcomes. To date, no study has investigated the role of oedema in the emergency surgical patient. This study assesses the incidence of oedema following emergency abdominal surgery and the value of early postoperative oedema measurement in predicting clinical outcome.

METHODS

A prospective cohort study of patients undergoing emergency abdominal surgery at a university unit over a two-month period was undertaken. Nutritional and clinical outcome data were collected and oedema was measured in the early postoperative period. Predictors of oedema and outcomes associated with postoperative oedema were identified through univariate and multivariate analysis.

RESULTS

Overall, 55 patients (median age: 66 years) were included in the study. Postoperative morbidity included ileus (n=22) and sepsis (n=6) with 12 deaths at follow-up. Postoperative oedema was present in 19 patients and was associated with prolonged perioperative fasting (107 vs 30 hours, p=0.009) but not with body mass index (24 kg/m(2) vs 27 kg/m(2), p=0.169) or preadmission weight loss (5% vs 3%, p=0.923). On multivariate analysis, oedema was independently associated with gastrointestinal recovery (B=6.91, p=0.038), artificial nutritional support requirement (odds ratio: 6.91, p=0.037) and overall survival (χ(2) =13.1, df=1, p=0.001).

CONCLUSIONS

Generalised oedema is common after emergency abdominal surgery and appears to independently predict gastrointestinal recovery, the need for artificial nutritional support and survival. Oedema is not associated with commonly applied markers of nutritional status such as body mass index or recent weight loss. Measurement of oedema offers utility in identifying those at risk of poor clinical outcome or those requiring artificial nutritional support following emergency abdominal surgery.

Considerations for numerical modeling of the pulmonary circulation--a review with a focus on pulmonary hypertension

Both in academic research and in clinical settings, virtual simulation of the cardiovascular system can be used to rapidly assess complex multivariable interactions between blood vessels, blood flow, and the heart. Moreover, metrics that can only be predicted with computational simulations (e.g., mechanical wall stress, oscillatory shear index, etc.) can be used to assess disease progression, for presurgical planning, and for interventional outcomes. Because the pulmonary vasculature is susceptible to a wide range of pathologies that directly impact and are affected by the hemodynamics (e.g., pulmonary hypertension), the ability to develop numerical models of pulmonary blood flow can be invaluable to the clinical scientist. Pulmonary hypertension is a devastating disease that can directly benefit from computational hemodynamics when used for diagnosis and basic research. In the present work, we provide a clinical overview of pulmonary hypertension with a focus on the hemodynamics, current treatments, and their limitations. Even with a rich history in computational modeling of the human circulation, hemodynamics in the pulmonary vasculature remains largely unexplored. Thus, we review the tasks involved in developing a computational model of pulmonary blood flow, namely vasculature reconstruction, meshing, and boundary conditions. We also address how inconsistencies between models can result in drastically different flow solutions and suggest avenues for future research opportunities. In its current state, the interpretation of this modeling technology can be subjective in a research environment and impractical for clinical practice. Therefore, considerations must be taken into account to make modeling reliable and reproducible in a laboratory setting and amenable to the vascular clinic. Finally, we discuss relevant existing models and how they have been used to gain insight into cardiopulmonary physiology and pathology.

Assessing seasonal variations and age patterns in mortality during the first year of life in Tanzania

Lack of birth and death registries in most of developing countries, particularly those in sub-Saharan Africa led to the establishment of Demographic Surveillance Systems (DSS) sites which monitor large population cohorts within defined geographical areas. DSS collects longitudinal data on migration, births, deaths and their causes via verbal autopsies. DSS data provide an opportunity to monitor many health indicators including mortality trends. Mortality rates in Sub-Sahara Africa show seasonal patterns due to high infant and child malaria-related mortality which is influenced by seasonal features present in environmental and climatic factors. However, it is unclear whether seasonal patterns differ by age in the first few months of life. This study provides an overview of approaches to assess, capture and detect seasonality peaks and patterns in mortality using the infant mortality data from the Rufiji DSS, Tanzania. Seasonality was best captured using Bayesian negative binomial models with time and cycle dependent seasonal parameters and autoregressive temporal error terms. Seasonal patterns are similar among different age groups during infancy and timing of their mortality peaks do not differ. Seasonality in mortality rates with two peaks per year is pronounced which corresponds to rainy seasons. Understanding of these trends is important for public health preparedness.

Short communication: comparison of the effects of heat stress on milk and component yields and somatic cell score in Holstein and Jersey cows

The objectives of this retrospective study were to (1) investigate the effects of heat stress (HS) climatic conditions and breed on milk and component yield for Holstein and Jersey cows on the same farm and (2) determine the effects of breed on udder health as measured by somatic cell score during HS climatic conditions. Data were collected from Dairy Herd Improvement Association records of 142 Jersey and 586 Holstein cows from the Bearden Dairy Research Center at Mississippi State University (Mississippi State). Heat stress climatic conditions were determined using a temperature-humidity index (THI) to combine dry bulb temperature and relative humidity into one measure. Two analyses were conducted to determine the effects of HS. Heat stress was defined as THI ≥ 72, and reported as HS+ for the first analysis and HS for the second analysis. The first analysis compared breeds during HS+ and non-heat-stress (HS-) conditions. Holstein milk yield decreased during HS+, whereas Jersey milk yield increased. Milk fat percentage for Holstein and Jersey cows declined during HS+. Holstein fat-corrected milk yield decreased during HS+, whereas Jersey fat-corrected milk yield during HS+ did not differ from that during HS-. During HS+, somatic cell score increased in milk from Holstein and Jersey cows compared with HS-. In the second analysis, HS was categorized as mild, moderate, or severe. The corresponding THI values were THI ≥ 72 but <79, THI ≥ 79 but <90, and THI ≥ 90. Holstein milk yield declined during moderate and severe HS, whereas Jersey milk yield declined during severe HS. Holstein milk fat percentage was less during moderate and severe HS compared with milk fat percentage during mild HS. Jersey milk fat percentage did not differ with regard to HS category. Jersey cows appeared to be more heat tolerant than Holstein cows; however, Holstein cows still produced larger volumes of milk.

Improved performance of nanowire-quantum-dot-polymer solar cells by chemical treatment of the quantum dot with ligand and solvent materials

We report a nanowire-quantum-dot-polymer solar cell consisting of a chemically treated CdSe quantum dot film deposited on n-type ZnO nanowires. The electron and hole collecting contacts are a fluorine-doped tin-oxide/zinc oxide layer and a P3HT/Au layer. This device architecture allows for enhanced light absorption and an efficient collection of photogenerated carriers. A detailed analysis of the chemical treatment of the quantum dots, their deposition, and the necessary annealing processes are discussed. We find that the surface treatment of CdSe quantum dots with pyridine, and the use of 1,2-ethanedithiol (EDT) ligands, critically improves the device performance. Annealing at 380 °C for 2 h is found to cause a structural conversion of the CdSe from its initial isolated quantum dot arrangement into a polycrystalline film with excellent surface conformality, thereby resulting in a further enhancement of device performance. Moreover, long-term annealing of 24 h leads to additional increases in device efficiency. Our best conversion efficiency reached for this type of cell is 3.4% under 85 mW cm(-2) illumination.