Distilling experience into a physically interpretable recommender system for computational model selection

Model selection is a chronic issue in computational science. The conventional approach relies heavily on human experience. However, gaining experience takes years and is severely inefficient. To address this issue, we distill human experience into a recommender system. A trained recommender system tells whether a computational model does well or poorly in handling a physical process. It also tells if a physical process is important for a quantity of interest. By accumulating this knowledge, the system is able to make recommendations about computational models. We showcase the power of the system by considering Reynolds-averaged-Navier-Stokes (RANS) model selection in the field of computational fluid dynamics (CFD). Since turbulence is stochastic, there is no universal RANS model, and RANS model selection has always been an issue. A working model recommending system saves fluid engineers years and allows junior CFD practitioners to make sensible model choices like senior ones.

Immune Cells and Immunosenescence

Aging is associated with progressive loss of physiological integrity, leading to impaired physical and mental functions as well as increased morbidity and mortality. With advancing age, the immune system is no longer able to adequately control autoimmunity, infections, or cancer. The abilities of the elderly to slow down undesirable effects of aging may depend on the genetic background, lifestyle, geographic region, and other presently unknown factors. Although most aspects of the immunity are constantly declining in relation to age, some features are retained, while e.g. the ability to produce high levels of cytokines, response to pathogens by increased inflammation, and imbalanced proteolytic activity are found in the elderly, and might eventually cause harm. In this context, it is important to differentiate between the effect of immunosenescence that is contributing to this decline and adaptations of the immune system that can be quickly reversed if necessary.

Fracture of the Occipital Condyle as an Incidental Finding during CT-Evaluation of a Maxillary Fracture

A 43-year-old male presented with blunt facial trauma after a motor-vehicle accident. CT-evaluation revealed a right-sided maxillary fracture and a fracture of the left occipital condyle. The fracture of the occipital condyle is potentially unstable and fatal cases have been described. Plain radiographs are not diagnostic. This occipital condyle fracture was an incidental finding during CT-evaluation of a maxillary fracture and is probably the first case with coronary CT scans of this type of fracture.

Histopathological grading systems analysis of oral squamous cell carcinomas of young patients

BACKGROUND

To analyze the clinicopathological profile of young patients (≤ 40 years) with oral SCC and correlate with a control group (≥ 50 years) by means of histopathological grading systems.

MATERIAL AND METHODS

14 young patients and 14 control patients were selected with similar clinical stage and tumor location. Demographic and clinical data were obtained from patient records and histological sections were evaluated according to four histopathological grading systems. Associations between categories of demographic and clinical data were performed through Chi-square test and Exact Fisher test. The survival analyzes were performed according to the Kaplan-Meier method.

RESULTS

The comparison between groups showed a greater association of treatment modalities in younger patients (p=0.022), they had a higher incidence of local recurrence and regional metastasis (p=0.018) and lower disease-free survival in 5 years (p=0.069). There was no difference in 5-year overall survival among the studied groups. There was no difference in histological grading between studied groups according to the four used systems.

CONCLUSIONS

This study showed that, despite tumors had similar histological grade and more therapeutic modalities were used in the young group, tumors in young patients had a higher incidence of recurrence/metastasis, showing tendency to a more aggressive behavior.

Localized Modeling of Biochemical and Flow Interactions during Cancer Cell Adhesion

This work focuses on one component of a larger research effort to develop a simulation tool to model populations of flowing cells. Specifically, in this study a local model of the biochemical interactions between circulating melanoma tumor cells (TC) and substrate adherent polymorphonuclear neutrophils (PMN) is developed. This model provides realistic three-dimensional distributions of bond formation and attendant attraction and repulsion forces that are consistent with the time dependent Computational Fluid Dynamics (CFD) framework of the full system model which accounts local pressure, shear and repulsion forces. The resulting full dynamics model enables exploration of TC adhesion to adherent PMNs, which is a known participating mechanism in melanoma cell metastasis. The model defines the adhesion molecules present on the TC and PMN cell surfaces, and calculates their interactions as the melanoma cell flows past the PMN. Biochemical rates of reactions between individual molecules are determined based on their local properties. The melanoma cell in the model expresses ICAM-1 molecules on its surface, and the PMN expresses the β-2 integrins LFA-1 and Mac-1. In this work the PMN is fixed to the substrate and is assumed fully rigid and of a prescribed shear-rate dependent shape obtained from micro-PIV experiments. The melanoma cell is transported with full six-degrees-of-freedom dynamics. Adhesion models, which represent the ability of molecules to bond and adhere the cells to each other, and repulsion models, which represent the various physical mechanisms of cellular repulsion, are incorporated with the CFD solver. All models are general enough to allow for future extensions, including arbitrary adhesion molecule types, and the ability to redefine the values of parameters to represent various cell types. The model presented in this study will be part of a clinical tool for development of personalized medical treatment programs.

Interventions to reduce or prevent obesity in pregnant women: a systematic review

BACKGROUND

Around 50% of women of childbearing age are either overweight [body mass index (BMI) 25-29.9 kg/m(2)] or obese (BMI ≥ 30 kg/m(2)). The antenatal period provides an opportunity to manage weight in pregnancy. This has the potential to reduce maternal and fetal complications associated with excess weight gain and obesity.

OBJECTIVES

To evaluate the effectiveness of dietary and lifestyle interventions in reducing or preventing obesity in pregnancy and to assess the beneficial and adverse effects of the interventions on obstetric, fetal and neonatal outcomes.

DATA SOURCES

Major electronic databases including MEDLINE, EMBASE, BIOSIS and Science Citation Index were searched (1950 until March 2011) to identify relevant citations. Language restrictions were not applied.

REVIEW METHODS

Systematic reviews of the effectiveness and harm of the interventions were carried out using a methodology in line with current recommendations. Studies that evaluated any dietary, physical activity or mixed approach intervention with the potential to influence weight change in pregnancy were included. The quality of the studies was assessed using accepted contemporary standards. Results were summarised as pooled relative risks (RRs) with 95% confidence intervals (CIs) for dichotomous data. Continuous data were summarised as mean difference (MD) with standard deviation. The quality of the overall evidence synthesised for each outcome was summarised using GRADE (Grading of Recommendations Assessment, Development, and Evaluation) methodology and reported graphically as a two-dimensional chart.

RESULTS

A total of 88 studies (40 randomised and 48 non-randomised and observational studies, involving 182,139 women) evaluated the effect of weight management interventions in pregnancy on maternal and fetal outcomes. Twenty-six studies involving 468,858 women reported the adverse effect of the interventions. Meta-analysis of 30 RCTs (4503 women) showed a reduction in weight gain in the intervention group of 0.97 kg compared with the control group (95% CI -1.60 kg to -0.34 kg; p = 0.003). Weight management interventions overall in pregnancy resulted in a significant reduction in the incidence of pre-eclampsia (RR 0.74, 95% CI 0.59 to 0.92; p = 0.008) and shoulder dystocia (RR 0.39, 95% CI 0.22 to 0.70; p = 0.02). Dietary interventions in pregnancy resulted in a significant decrease in the risk of pre-eclampsia (RR 0.67, 95% CI 0.53 to 0.85; p = 0.0009), gestational hypertension (RR 0.30, 95% CI 0.10 to 0.88; p = 0.03) and preterm birth (RR 0.68, 95% CI 0.48 to 0.96; p = 0.03) and showed a trend in reducing the incidence of gestational diabetes (RR 0.52, 95% CI 0.27 to 1.03). There were no differences in the incidence of small-for-gestational-age infants between the groups (RR 0.99, 95% CI 0.76 to 1.29). There were no significant maternal or fetal adverse effects observed for the interventions in the included trials. The overall strength of evidence for weight gain in pregnancy and birthweight was moderate for all interventions considered together. There was high-quality evidence for small-for-gestational-age infants as an outcome. The quality of evidence for all interventions on pregnancy outcomes was very low to moderate. The quality of evidence for all adverse outcomes was very low.

LIMITATIONS

The included studies varied in the reporting of population, intensity, type and frequency of intervention and patient complience, limiting the interpretation of the findings. There was significant heterogeneity for the beneficial effect of diet on gestational weight gain.

CONCLUSIONS

Interventions in pregnancy to manage weight result in a significant reduction in weight gain in pregnancy (evidence quality was moderate). Dietary interventions are the most effective type of intervention in pregnancy in reducing gestational weight gain and the risks of pre-eclampsia, gestational hypertension and shoulder dystocia. There is no evidence of harm as a result of the dietary and physical activity-based interventions in pregnancy. Individual patient data meta-analysis is needed to provide robust evidence on the differential effect of intervention in various groups based on BMI, age, parity, socioeconomic status and medical conditions in pregnancy.

Effects of interventions in pregnancy on maternal weight and obstetric outcomes: meta-analysis of randomised evidence

OBJECTIVE

To evaluate the effects of dietary and lifestyle interventions in pregnancy on maternal and fetal weight and to quantify the effects of these interventions on obstetric outcomes.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Major databases from inception to January 2012 without language restrictions.

STUDY SELECTION

Randomised controlled trials that evaluated any dietary or lifestyle interventions with potential to influence maternal weight during pregnancy and outcomes of pregnancy.

DATA SYNTHESIS

Results summarised as relative risks for dichotomous data and mean differences for continuous data.

RESULTS

We identified 44 relevant randomised controlled trials (7278 women) evaluating three categories of interventions: diet, physical activity, and a mixed approach. Overall, there was 1.42 kg reduction (95% confidence interval 0.95 to 1.89 kg) in gestational weight gain with any intervention compared with control. With all interventions combined, there were no significant differences in birth weight (mean difference -50 g, -100 to 0 g) and the incidence of large for gestational age (relative risk 0.85, 0.66 to 1.09) or small for gestational age (1.00, 0.78 to 1.28) babies between the groups, though by itself physical activity was associated with reduced birth weight (mean difference -60 g, -120 to -10 g). Interventions were associated with a reduced the risk of pre-eclampsia (0.74, 0.60 to 0.92) and shoulder dystocia (0.39, 0.22 to 0.70), with no significant effect on other critically important outcomes. Dietary intervention resulted in the largest reduction in maternal gestational weight gain (3.84 kg, 2.45 to 5.22 kg), with improved pregnancy outcomes compared with other interventions. The overall evidence rating was low to very low for important outcomes such as pre-eclampsia, gestational diabetes, gestational hypertension, and preterm delivery.

CONCLUSIONS

Dietary and lifestyle interventions in pregnancy can reduce maternal gestational weight gain and improve outcomes for both mother and baby. Among the interventions, those based on diet are the most effective and are associated with reductions in maternal gestational weight gain and improved obstetric outcomes.

Study of local hydrodynamic environment in cell-substrate adhesion using side-view μPIV technology

Tumor cell adhesion to the endothelium under shear flow conditions is a critical step that results in circulation-mediated tumor metastasis. This study presents experimental and computational techniques for studying the local hydrodynamic environment around adherent cells and how local shear conditions affect cell-cell interactions on the endothelium in tumor cell adhesion. To study the local hydrodynamic profile around heterotypic adherent cells, a side-view flow chamber assay coupled with micro particle imaging velocimetry (μPIV) technique was developed, where interactions between leukocytes and tumor cells in the near-endothelial wall region and the local shear flow environment were characterized. Computational fluid dynamics (CFD) simulations were also used to obtain quantitative flow properties around those adherent cells. Results showed that cell dimension and relative cell-cell positions had strong influence on local shear rates. The velocity profile above leukocytes and tumor cells displayed very different patterns. Larger cell deformations led to less disturbance to the flow. Local shear rates above smaller cells were observed to be more affected by relative positions between two cells.

Stellar and primordial nucleosynthesis of 7Be: measurement of 3He(alpha,gamma)7Be

The 3He(alpha,gamma)7Be reaction presently represents the largest nuclear uncertainty in the predicted solar neutrino flux and has important implications on the big bang nucleosynthesis, i.e., the production of primordial 7Li. We present here the results of an experiment using the recoil separator ERNA (European Recoil separator for Nuclear Astrophysics) to detect directly the 7Be ejectiles. In addition, off-beam activation and coincidence gamma-ray measurements were performed at selected energies. At energies above 1 MeV a large discrepancy compared to previous results is observed both in the absolute value and in the energy dependence of the cross section. Based on the available data and models, a robust estimate of the cross section at the astrophysical relevant energies is proposed.

[The GRADE System. An international approach to standardize the graduation of evidence and recommendations in guidelines]

Clinical practice guidelines have become an important source of information to support clinicians in the management of individual patients. However, current guideline methods have limitations that include the lack of separating the quality of evidence from the strength of recommendations. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) working group, an international collaboration of guideline developers, methodologists, and clinicians have developed a system that addresses these shortcomings. Core elements include transparent methodology for grading the quality of evidence, the distinction between quality of the evidence and strength of a recommendation, an explicit balancing of benefits and harms of health care interventions, an explicit recognition of the values and preferences that underlie recommendations. The GRADE system has been piloted in various practice settings to ensure that it captures the complexity involved in evidence assessment and grading recommendations while maintaining simplicity and practicality. Many guideline organizations and medical societies have endorsed the system and adopted it for their guideline processes.

Systemic prokinetic pharmacologic treatment for postoperative adynamic ileus following abdominal surgery in adults

BACKGROUND

Postoperative adynamic bowel atony interferes with recovery following abdominal surgery. Prokinetic pharmacologic drugs are widely used to accelerate postoperative recovery.

OBJECTIVES

To evaluate the benefits and harms of systemic acting prokinetic drugs to treat postoperative adynamic ileus in patients undergoing abdominal surgery.

SEARCH STRATEGY

Trials were identified by computerised searches of the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and the Cochrane Colorectal Cancer Group specialised register. The reference lists of included trials and review articles were tracked and authors contacted.

SELECTION CRITERIA

Randomised controlled parallel-group trials (RCT) comparing the effect of systemically acting prokinetic drugs against placebo or no intervention.

DATA COLLECTION AND ANALYSIS

Four reviewers independently extracted the data and assessed trial quality. Trial authors were contacted for additional information if needed.

MAIN RESULTS

Thirty-nine RCTs met the inclusion criteria contributing a total of 4615 participants. Most trials enrolled a small number of patients and showed moderate to poor (reporting of) methodological quality, in particular regarding allocation concealment and intention-to-treat analysis. Fifteen systemic acting prokinetic drugs were investigated and ten comparisons could be summarized. Six RCTs support the effect of Alvimopan, a novel peripheral mu receptor antagonist. However, the trials do not meet reporting guidelines and the drug is still in an investigational stage. Erythromycin showed homogenous and consistent absence of effect across all included trials and outcomes. The evidence is insufficient to recommend the use of cholecystokinin-like drugs, cisapride, dopamine-antagonists, propranolol or vasopressin. Effects are either inconsistent across outcomes, or trials are too small and often of poor methodological quality. Cisapride has been withdrawn from the market due to adverse cardiac events in many countries. Intravenous lidocaine and neostigmine might show a potential effect, but more evidence on clinically relevant outcomes is needed. Heterogeneity among included trials was seen in 10 comparisons. No major adverse drug effects were evident.

AUTHORS' CONCLUSIONS

Alvimopan may prove to be beneficial but proper judgement needs adherence to reporting standards. Further trials are needed on intravenous lidocaine and neostigmine. The remaining drugs can not be recommended due to lack of evidence or absence of effect.

Impact of short evidence summaries in discharge letters on adherence of practitioners to discharge medication. A cluster-randomised controlled trial

BACKGROUND

International concern about quality of medical care has led to intensive study of interventions to ensure care is consistent with best evidence. Simple, inexpensive, feasible and effective interventions remain limited.

OBJECTIVE

We examined the impact of one-sentence evidence summaries appended to consultants' letters to primary care practitioners on adherence of the practitioners to recommendations made by the consultants regarding medication for patients with chronic medical problems.

DESIGN

Cluster-randomised trial.

SETTING

Secondary/primary care interface (urban district hospital/referral practices).

PARTICIPANTS

178 practices received one or more discharge letters with evidence summaries. The 66 practices in the intervention group provided feedback on 172 letters, and the 56 practices in the control group provided feedback on 96 letters.

RESULTS

Appending an evidence summary to discharge letters resulted in a decrease in non-adherence to discharge medication from 29.6% to 18.5% (difference adjusted for underlying medical condition 12.5%; p = 0.039). Among the five possible reasons for discontinuing discharge medication, the evidence summaries seemed to have the largest impact on budget-related reasons for discontinuation (2.6% in the intervention versus 10.7% in the control group (p = 0.052)). Most clinicians (72%) were enthusiastic about continuing receiving evidence summaries with discharge letters in routine care.

CONCLUSIONS

The one-sentence evidence summary is a simple, inexpensive, well-accepted intervention that may improve primary care practitioners' adherence to evidence-based consultant recommendations.

Randomisation to protect against selection bias in healthcare trials

BACKGROUND

Randomised trials use the play of chance to assign participants to comparison groups. The unpredictability of the process, if not subverted, should prevent systematic differences between comparison groups (selection bias), provided that a sufficient number of people are randomised.

OBJECTIVES

To assess the effects of randomisation and concealment of allocation on the results of healthcare trials.

SEARCH STRATEGY

We searched the Cochrane Methodology Register, MEDLINE, SciSearch, reference lists up to August 2000 and used personal communication.

SELECTION CRITERIA

Cohorts of trials, systematic reviews or meta-analyses of healthcare interventions that compared outcomes or prognostic factors for one of the following comparisons: randomised versus non-randomised trials, randomised trials with adequately versus inadequately concealed allocation, or high versus low quality trials where selection bias could not be separated from other sources of bias.

DATA COLLECTION AND ANALYSIS

One of us went through all of the citations in the Cochrane Methodology Register and accumulated reference lists. Studies that appeared to meet the inclusion criteria were retrieved and assessed independently by two of the reviewers. The methodological quality of included studies was appraised and information extracted by one of us and checked by a second. Tabular summaries of the results were prepared for each comparison and the results across studies were assessed qualitatively to identify common trends or discrepancies.

MAIN RESULTS

We identified 32 studies including over 3000 trials. Twenty-two studies compared randomised versus non-randomised trials, three compared adequately versus inadequately concealed allocation, and nine compared high versus low quality trials (some studies included more than one comparison). Five studies were of high methodological quality. In 15 of the 22 studies that compared randomised and non-randomised trials of the same intervention, important differences were found in the estimates of effect. Some of these differences were due to a poorer prognosis in the control groups in the non-randomised trials. The results of the other seven studies that compared randomised and non-randomised trials across different interventions are less clear. Comparisons of adequately and inadequately concealed allocation in randomised trials of the same intervention provided high quality evidence that concealment can be crucial in achieving similar treatment groups and, therefore, unbiased estimates of treatment effects. Studies with inadequate concealment tended to overestimate treatment effects. Comparisons of high and low quality trials of the same intervention have found important differences in estimates of effect, but it is not possible to determine the extent to which these differences can be attributed to randomisation or concealment of allocation. Omitting comparisons between randomised trials and non-randomised trials using historical controls did not substantially alter the results or conclusions of our review.

AUTHORS' CONCLUSIONS

On average, non-randomised trials and randomised trials with inadequate concealment of allocation tend to result in larger estimates of effect than randomised trials with adequately concealed allocation. However, it is not generally possible to predict the magnitude, or even the direction, of possible selection biases and consequent distortions of treatment effects.

Beurteilung von Schmerz bei Demenz (BESD)

BACKGROUND

The observation scale PAINAD (pain assessment in advanced dementia) is composed of five behavioral categories: breathing, vocalization, facial expression, body language, and consolability. The present study investigates the construct validity of the German version.

PATIENTS AND METHODS

We conducted a prospective one-dimensional observation study with repeated measurements (t(1)=pretreatment, t(2)=2 h posttreatment, t(3)=24 h posttreatment). The sample consisted of 12 verbally noncommunicative demented inpatients with severe comorbidity treated in three geriatric clinics. Their age was M=84.3 years (SD=4.4) on the average. Ten of them were female. Inclusion criteria were pain-related physical illness and observed pain behavior. Every patient was treated with analgesics after t(1). After t(2) the medication was discontinued in five patients until t(3). Nurses documented the PAINAD scores after an observation period of 2 min during routine care.

RESULTS

Pain behavior at t(2) diminished considerably displaying a large effect size. Scores continued to be low at t(3) only in the sample with continued medication. Scores in the other part of the sample returned to initial values.

CONCLUSION

The data demonstrate that pain medication strongly impacts the pain behavior of demented patients. The outcome supports the assumption that PAINAD really measures pain.

Leitlinien

Now more than ever physicians need effective management of the constantly increasing flood of medical information. The authors discuss possibilities for developing clinical guidelines as a core element of this information management and the requirements of these possibilities. The development of clinical guidelines is a process also suitable for involving patient and consumer expertise in health care. Models of involving patients are described and how these processes can build an important base for shared decision making of physicians and patients.

Cellular neural networks (CNN) with linear weight functions for a prediction of epileptic seizures

In this paper, we present a novel approach to the prediction of epileptic seizures using boolean CNN with linear weight functions. Three different binary pattern occurrence behaviours will be discussed and analysed for several invasive recordings of brain electrical activity. Furthermore analogic binary pattern detection algorithms will be introduced for a possible prediction of epileptic seizures.

Palliative Care f�r Patienten mit fortgeschrittener Demenz: Values Based statt Evidence Based Practice

For the treatment of patients with advanced dementia, we could not find any evidence based guidelines to help in decision making. Individual values and expected quality of life must be the leading goals of any intervention. Symptom control and relieving suffering are core values of palliative care, but the recognition of discomfort needs qualified assessment skills. Pain assessment with common tools like the VAS fails in patients with cognitive impairment and inability to communicate; instruments like Doloplus and ECPA can be helpful to assess behavioral changes as expression of pain. The treatment of acute and chronic pain in advanced dementia is still not sufficient and needs improvement. Oral feeding in advanced dementia becomes more and more difficult. No randomized controlled study has found evidence that tube feeding will reduce the risk of aspiration or prolong life expectancy. Eating may be the only meaningful activity that remains for the patient; artificial feeding cannot serve the same function. All final complications, like pneumonia, call for a decision making process. Those who care for and care about these patients must make decisions. The feelings of the family have to be considered, but the probable will of the patient, his dignity and quality of life must not be overridden.

Do short courses in evidence based medicine improve knowledge and skills? Validation of Berlin questionnaire and before and after study of courses in evidence based medicine

OBJECTIVE

To develop and validate an instrument for measuring knowledge and skills in evidence based medicine and to investigate whether short courses in evidence based medicine lead to a meaningful increase in knowledge and skills.

DESIGN

Development and validation of an assessment instrument and before and after study.

SETTING

Various postgraduate short courses in evidence based medicine in Germany.

PARTICIPANTS

The instrument was validated with experts in evidence based medicine, postgraduate doctors, and medical students. The effect of courses was assessed by postgraduate doctors from medical and surgical backgrounds.

INTERVENTION

Intensive 3 day courses in evidence based medicine delivered through tutor facilitated small groups.

MAIN OUTCOME MEASURE

Increase in knowledge and skills.

RESULTS

The questionnaire distinguished reliably between groups with different expertise in evidence based medicine. Experts attained a threefold higher average score than students. Postgraduates who had not attended a course performed better than students but significantly worse than experts. Knowledge and skills in evidence based medicine increased after the course by 57% (mean score before course 6.3 (SD 2.9) v 9.9 (SD 2.8), P<0.001). No difference was found among experts or students in absence of an intervention.

CONCLUSIONS

The instrument reliably assessed knowledge and skills in evidence based medicine. An intensive 3 day course in evidence based medicine led to a significant increase in knowledge and skills.

C1-inhibitor for prophylaxis of xenograft rejection after pig to cynomolgus monkey kidney transplantation

BACKGROUND

Early rejection of discordant porcine xenografts in primate recipients is initiated by the intragraft binding of either preformed (hyperacute xenograft rejection) or induced (acute vascular rejection) antiporcine recipient antibodies with subsequent complement activation via the classical pathway. We have investigated the efficacy of the supplemental administration of C1-inhibitor (C1-INH), a specific inhibitor of the classical complement activation pathway, for prophylaxis of xenograft rejection in a pig to primate kidney xenotransplantation setting.

METHODS

Based on the results of pharmacokinetic studies performed in two nontransplanted monkeys, supplemental C1-INH therapy was administered daily to three Cynomolgus monkeys receiving a life-supporting porcine kidney transplant together with cyclophosphamide-induction/cyclosporine A/mycophenolat-mofetil/steroid immunosuppressive therapy.

RESULTS

In the three monkeys receiving porcine kidney xenografts and continuous C1-INH treatment none of the grafts underwent hyperacute rejection; all xenografts showed initial function. Recipient survival was 13, 15, and 5 days. No graft was lost due to acute vascular rejection. All animals died with a functioning graft (latest creatinine 96, 112, and 96 micromol/liter) due to bacterial septicemia.

CONCLUSION

We conclude that, in our model, supplemental C1-INH therapy together with a standard immunosuppressive regimen can be helpful for prevention of xenograft rejection in a pig to primate kidney xenotransplantation setting. The optimal dose and duration of C1-INH treatment, however, has yet to be determined.

(22)Ne(alpha,n)(25)Mg: the key neutron source in massive stars

The excitation function of the reaction (22)Ne(alpha,n)(25)Mg, the key neutron source in the astrophysical s process in massive stars, has been determined from threshold at E(alpha) = 570 up to 1450 keV with an experimental sensitivity of 10(-11) b. For all resonances in this energy range new resonance parameters have been measured. For a possible resonance at about 635 keV a new upper limit omega gamma < 60 neV for the strength was obtained. Based on the new data, improved reaction rates were calculated as a function of temperature. The new uncertainty limits are considerably smaller than in previous determinations, ruling out the large enhancement factors, up to 500, assumed in some stellar model calculations.

[Development of quality assurance criteria for continuing education in evidence-based medicine]

OBJECTIVE

To develop a set of core contents for teaching evidence-based medicine (EBM).

METHOD

Description of basic principles from clinical epidemiology, medical statistics and literature search essential for health care practitioners to perform critical appraisal of the medical literature. Based on textbooks for EBM and clinical epidemiology and guided by the EBM courses at McMaster university and the Oxford Centre for EBM, core contents were defined. Decision on inclusion was made by consensus.

RESULTS

The core contents for the Berlin curriculum in EBM covers 3 areas: 1. General information on the methods of experimental and observational clinical studies, principles of EMB, basic statistical concepts, and literature search. 2. Tools for critical appraisal of primary studies required for medical decision making: therapy, diagnosis, prognosis, and harm. 3. Evidence-based summary reports: meta-analysis and guidelines.

CONCLUSIONS

The contents of EBM can be precisely defined. They are transparent, explicit and communicable and present a reproducible basis for the different forms of teaching EBM.

12C(alpha,gamma)16O: the key reaction in stellar nucleosynthesis

The angular distributions of gamma rays from the 12C(alpha,gamma)16O reaction have been measured at 20 energy points in the energy range E(cm) = 0.95 to 2.8 MeV. The sensitivity of the present experiment compared to previous direct investigations was raised by 1-2 orders of magnitude, by using an array of highly efficient ( 100%) Ge detectors shielded actively with BGOs, as well as high beam currents of up to 500 microA that were provided by the Stuttgart Dynamitron accelerator. The S(E1) and S(E2) factors deduced from the gamma angular distributions have been extrapolated to the range of helium burning temperatures applying the R-matrix method, which yielded S(300)(E1) = (76+/-20) keV b and S(300)(E2) = (85+/-30) keV b.

[Severely injured patients after the initial phase--vegetative state or remaining cognitive functions?]

BACKGROUND

We wanted to quantify improvements in the subacute rehabilitation phase in patients with severe brain injuries classified as vegetative or minimal brain consciousness.

MATERIAL AND METHODS

Five patients were studied during a 12 months period using a method called Coma Recovery Scale (CRS) as described by Giacino et al. (1991). The parameters measured included visual and hearing functions, motor functioning, oromotor/verbal function, communication, and arousal. The observations of the patients and commandos given were standardised in a manual, and the responses achieved from the patients were recorded according to a scale for each parameter.

RESULTS

This procedure for measuring closely the progress over time in these severely brain injured patients, was used for planning a realistic rehabilitation program. It was found to be very practical in communication with relatives of the patients and with the other therapists involved.

INTERPRETATION

By decomposing the cognitive functions by this method using all the available possibilities for inputs, even minimal improvement in the cognitive functions mentioned could be uncovered and recorded.

Studies of symptoms in primary care

Publications on the frequency of defined symptoms in the practice setting, underlying conditions and prognosis have been rare in the past. Also, studies addressing these questions have suffered from several methodological problems. We therefore developed criteria to help investigators improve the quality of study design, implementation and publication. Studies evaluating symptoms in practice can make an important contribution to a more rational approach to diagnostic decision making especially in primary care.

A primate model for discordant pig to primate kidney xenotransplantation without hyperacute graft rejection

Organs transplanted between phylogenetically disparate species, such as from the pig into the primate, are subject to intragraft deposition of preformed recipient immunoglobulin M (IgM) antibodies with subsequent complement activation finally leading to complete and rapid destruction of the xenograft (hyperacute graft rejection, HAR). Current therapeutic strategies for abrogation of HAR include pretransplant antibody absorption by specific or nonspecific extracorporeal column perfusion, ex vivo donor organ perfusion, the administration of substances interfering with complement activation, or even the genetic alteration of the donor. Here, in the pig to cynomolgus monkey species combination, we are describing an experimental model for abrogation of HAR by using large, relative to the recipient weight, oversized donor kidneys as xenotransplants. Porcine kidney xenotransplantation (n = 15) was performed using large white pigs of different weights and ages as organ donors and cynomolgus monkeys as recipients. In grafts with an organ weight below 50 g (20 to 48 g, median 25 g), primary nonfunction (PNF) of the porcine kidney was observed in 11 out of 12 cases and complete HAR in 5 out of 12 experiments. In contrast, none of three grafts with a donor organ weight >70 g showed signs of HAR or PNF. In one animal, a second porcine kidney from the same donor (23 g) was successfully transplanted immediately after HAR and subsequent removal of a first porcine kidney (20 g). By using appropriate immunohistochemistry stainings of reperfusion biopsies, profound deposition of recipient natural antibodies in both small and large xenografts was shown, with only scarce deposition of C3 and C5b-9 in the latter, indicating only incomplete intragraft activation of the complement cascade in these organs. Intraoperative cardiac output (CO) measurements performed in 7 experiments demonstrated a 20 to 50% decrease in CO following reperfusion in 6 out of 7 grafts irrespective of the donor organ weight. The intraoperative decrease in CO was not associated with perioperative morbidity or mortality. The use of oversized doner kidneys can enable the study of a variety of immunologic and physiologic sequela beyond HAR associated with life-supporting discordant primate kidney transplantation.

Practice variations in the evaluation of adult candidates for cadaveric kidney transplantation: a survey of the European Transplant Centers

BACKGROUND

This survey was conducted to investigate similarities and differences in the diagnostic evaluation of adult candidates for cadaveric renal transplantation and the criteria for acceptance to the cadaveric renal transplant waiting-list in the European transplant centers.

METHODS

A questionnaire listing 45 diagnostic procedures (consultations of 9 specialties, 18 imaging techniques and 18 laboratory investigations), 45 medical conditions constituting possible reasons for exclusion from renal transplantation, and 10 properties characterizing the responding transplant center was sent to 214 European transplant centers.

RESULTS

A completed questionnaire was returned by 154 of 214 centers (72%). Significant disagreement (P<0.001) exists about the necessity of 28 of the 45 surveyed diagnostic procedures and about the acceptability of transplant candidates for 15 of the 45 surveyed medical conditions. The influence of center characteristics on the observed practice variations was examined by multinomial logistic regression (factors: Center size, waiting-list pressure, responsibility for organizing the diagnostic work-up, status of transplant center, responsibility for decision about acceptance of candidates and geographic location of center): In 13 of 28 controversial diagnostic procedures, geographic location of the centers turned out to be the only significant determining factor (P<0.001), whereas the dissent about medical conditions is not influenced significantly by the analyzed factors.

CONCLUSION

The detected significant practice variations in the evaluation of renal transplant candidates may either indicate where scientific evidence is missing and more clinical research is needed or where the existing evidence has not been adequately disseminated and convincing guidelines should be established.

Effect of ethanol on dynamic visual acuity during vertical body oscillation in healthy volunteers

Visual orientation is the most important sensory input during locomotion (e.g. walking, driving a car, riding a bicycle). We investigated dynamic visual acuity (DVA) during vertical body-oscillations (amplitude 5 cm; frequency 1.5 Hz) in 12 healthy subjects before and twice after ethanol consumption. During oscillation, vertical eye movements were recorded under two test conditions: with eyes closed (EC) and during DVA testing. A significant increase in vertical eye-amplitude after ethanol ingestion occurred only during EC tests, as a possible sign of vestibular hyperreaction. During vestibular stimulation alone (EC), ethanol did not affect the phase shift between stimulus and eye movements. However, when the subjects were given an additional visual stimulus (DVA), the post-alcohol phase shift rose significantly. Surprisingly, the post-alcohol phase shift values for the two test conditions showed no significant differences. After ethanol ingestion we found no changes in static visual acuity but a significant loss of DVA. Volunteers with a change of DVA threshold (DVAT) showed significantly (P = 0.004) higher post-alcoholic changes in the phase shift. In summary, low doses of ethanol disturbed the visually guided oculomotor response during fixation of an earth-fixed target while the observer was subject to linear vertical acceleration. This effect led to an increasing delay between the beginning of body and eye movements. The consequence was an increasing phase shift and thus a decrease in DVA during whole-body oscillation which was comparable to movements during human locomotion.

The localization of an imaginary target under the influence of caloric vestibular stimulation in healthy adults

It is well known that fixation of an imaginary target (IT) can influence the vestibulo-ocular reflex, but reports on the effect of peripheral vestibular stimulation on the localization of an IT are still lacking. In a prospective study, errors in pointing towards an IT without and after cold caloric vestibular stimulation (VS) were investigated in 24 right-handed volunteers with the head tilted backwards by 60 degrees. After the stationary target had been extinguished for 120 s each subject had to point towards the target position as remembered in darkness. The vestibular response was recorded by electronystagmography. Without VS 73% of the volunteers showed a systematic horizontal pointing error towards the right side. VS led to an increased horizontal pointing error in the direction of the slow phase of the induced nystagmus and the degree of deviation showed a significant (P = 0.001) positive correlation (r = 0.32) with the amplitude of the calorically induced nystagmus. In summary, an IT is not merely a useful visual stimulus for influencing the vestibulo-ocular reflex during linear and angular acceleration. A peripheral vestibular stimulation is itself able to change the position of an IT significantly and the extent of deviation shows a significant correlation with the amplitude of the evoked nystagmus.

Dynamic visual acuity during linear acceleration along the inter-aural axis

We investigated visual-vestibular interactions during linear acceleration along the inter-aural axis. Eighteen healthy volunteers and two patients with central neurological diseases were subjected to transaural linear acceleration in the direction of gravity force (frequency: 0.5-1.5 Hz; amplitude: 5 cm). During linear acceleration, eye movements were recorded under three test conditions: eyes closed (EC), while staring at an imaginary target (IT) and during the testing of dynamic visual acuity (DVA). As parameters of evaluation we used the amplitude of horizontal eye movements, phase shift and the decrease of DVA threshold (DVAT). Under all test conditions, eye amplitude increased with rising stimulus frequency and exceeded, especially in the higher frequency range, a hypothetically calculated eye amplitude for smooth pursuit. The combination of a visual and vestibular input (DVA and IT) led to a better compensation (lower phase shift) than under vestibular stimulation alone (EC). Eye movements during low-frequency stimulation depended more on the visual system while responses in the higher frequency range were mainly triggered by the otolith organ. At 1.5 Hz the compensatory function of the visual-vestibular system was limited (rising phase shift) and DVAT decreased even in a significant number of healthy subjects. Patients with diseases of the central nervous system showed a higher phase shift and thus a stronger decrease of DVAT (two levels) already at a stimulus frequency of 1.25 Hz.