ASXL1 mutations are associated with a response to alvocidib and 5-azacytidine combination in myelodysplastic neoplasms

Inhibitors of anti-apoptotic BCL-2 family proteins in combination with chemotherapy and hypomethylating agents (HMA) are promising therapeutic approaches in acute myeloid leukemia (AML) and high-risk myelodysplastic syndromes (MDS). Alvocidib, a cyclin-dependent kinase 9 (CDK9) inhibitor and indirect transcriptional repressor of the anti-apoptotic factor MCL-1, has previously shown clinical activity in AML. Availability of biomarkers for response to the alvocidib + 5-azacytidine (5-AZA) could also extend the rationale of this treatment concept to high-risk MDS. In this study, we performed a comprehensive in vitro assessment of alvocidib and 5-AZA effects in N=45 high-risk MDS patients. Our data revealed additive cytotoxic effects of the combination treatment. Mutational profiling of MDS samples identified ASXL1 mutations as predictors of response. Further, increased response rates were associated with higher gene expression of the pro-apoptotic factor NOXA in ASXL1-mutated samples. The higher sensitivity of ASXL1 mutant cells to the combination treatment was confirmed in vivo in ASXL1Y588X transgenic mice. Overall, our study demonstrated augmented activity for the alvocidib + 5-AZA combination in higher-risk MDS and identified ASXL1 mutations as a biomarker of response for potential stratification studies.

Myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions: reevaluation of the defining characteristics in a registry-based cohort

In a registry-based analysis of 135 patients with "myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions" (MLN-TK; FIP1L1::PDGFRA, n = 78; PDGFRB, diverse fusions, n = 26; FGFR1, diverse, n = 9; JAK2, diverse, n = 11; ETV6::ABL1, n = 11), we sought to evaluate the disease-defining characteristics. In 81/135 (60%) evaluable patients, hypereosinophilia (>1.5 × 109/l) was observed in 40/44 (91%) FIP1L1::PDGFRA and 7/7 (100%) ETV6::ABL1 positive patients but only in 13/30 (43%) patients with PDGFRB, FGFR1, and JAK2 fusion genes while 9/30 (30%) patients had no eosinophilia. Monocytosis >1 × 109/l was identified in 27/81 (33%) patients, most frequently in association with hypereosinophilia (23/27, 85%). Overall, a blast phase (BP) was diagnosed in 38/135 (28%) patients (myeloid, 61%; lymphoid, 39%), which was at extramedullary sites in 18 (47%) patients. The comparison between patients with PDGFRA/PDGFRB vs. FGFR1, JAK2, and ETV6::ABL1 fusion genes revealed a similar occurrence of primary BP (17/104, 16% vs. 8/31 26%, p = 0.32), a lower frequency (5/87, 6% vs. 8/23, 35%, p = 0.003) of and a later progression (median 87 vs. 19 months, p = 0.053) into secondary BP, and a better overall survival from diagnosis of BP (17.1 vs. 1.7 years, p < 0.0008). We conclude that hypereosinophilia with or without monocytosis and various phenotypes of BP occur at variable frequencies in MLN-TK.

Significant improvement of bone marrow-derived MSC expansion from MDS patients by defined xeno-free medium

BACKGROUND

Robust and reliable in vitro and in vivo models of primary cells are necessary to study the pathomechanisms of Myelodysplastic Neoplasms (MDS) and identify novel therapeutic strategies. MDS-derived hematopoietic stem and progenitor cells (HSPCs) are reliant on the support of bone marrow (BM) derived mesenchymal stroma cells (MSCs). Therefore, isolation and expansion of MCSs are essential for successfully modeling this disease. For the clinical use of healthy MSCs isolated from human BM, umbilical cord blood or adipose tissue, several studies showed that xeno-free (XF) culture conditions resulted in superior growth kinetics compared to MSCs cultured in the presence of fetal bovine serum (FBS). In this present study, we investigate, whether the replacement of a commercially available MSC expansion medium containing FBS with a XF medium is beneficial for the expansion of MSCs derived from BM of MDS patients which are often difficult to cultivate.

METHODS

MSCs isolated from BM of MDS patients were cultured and expanded in MSC expansion medium with FBS or XF supplement. Subsequently, the impact of culture media on growth kinetics, morphology, immunophenotype, clonogenic potential, differentiation capacity, gene expression profiles and ability to engraft in immunodeficient mouse models was evaluated.

RESULTS

Significant higher cell numbers with an increase in clonogenic potential were observed during culture of MDS MSCs with XF medium compared to medium containing FBS. Differential gene expression showed an increase in transcripts associated with MSC stemness after expansion with XF. Furthermore, immunophenotypes of the MSCs and their ability to differentiate into osteoblasts, adipocytes or chondroblasts remained stable. MSCs expanded with XF media were similarly supportive for creating MDS xenografts in vivo as MSCs expanded with FBS.

CONCLUSION

Our data indicate that with XF media, higher cell numbers of MDS MSCs can be obtained with overall improved characteristics in in vitro and in vivo experimental models.

Inhibition of lysyl oxidases synergizes with 5-azacytidine to restore erythropoiesis in myelodysplastic and myeloid malignancies

Limited response rates and frequent relapses during standard of care with hypomethylating agents in myelodysplastic neoplasms (MN) require urgent improvement of this treatment indication. Here, by combining 5-azacytidine (5-AZA) with the pan-lysyl oxidase inhibitor PXS-5505, we demonstrate superior restoration of erythroid differentiation in hematopoietic stem and progenitor cells (HSPCs) of MN patients in 20/31 cases (65%) versus 9/31 cases (29%) treated with 5-AZA alone. This effect requires direct contact of HSPCs with bone marrow stroma components and is dependent on integrin signaling. We further confirm these results in vivo using a bone marrow niche-dependent MN xenograft model in female NSG mice, in which we additionally demonstrate an enforced reduction of dominant clones as well as significant attenuation of disease expansion and normalization of spleen sizes. Overall, these results lay out a strong pre-clinical rationale for efficacy of combination treatment of 5-AZA with PXS-5505 especially for anemic MN.

[Mobbing Among Hospital Physicians]

OBJECTIVES

Bullying in the workplace is considered an interpersonal stress factor. Occupational stress and mental health among physicians is increasingly becoming the focus of public attention. The extent to which mobbing plays a role in this has hardly been investigated yet. The aim of this study is to provide data on the prevalence of bullying among hospital physicians in Germany and possible correlations with occupational stress and mental health.

METHODS

Within the framework of two cross-sectional studies, 692 hospital physicians in the field of psychiatry/psychotherapy (P/PT) and 667 hospital physicians in intensive care (IM) were interviewed at conferences. Standardized questionnaires on mobbing experience, occupational stress and mental health (single item from COPSOQ, BDI-II, ERI, MBI) were used.

RESULTS

Bullying was experienced by 4.6% (n=61) of the respondents. IM and women physicians were more often affected (not significant) and correlations with occupational stress (ERI), overcommitment (OC), emotional exhaustion (MBI) and depression (BDI-II) were found.

CONCLUSION

Our data on a large cohort of physicians in specialties with different exposure profiles show that a relevant proportion is affected by bullying and that bullying is related to the experience of occupational stress as well as mental health impairments. From this, implications for institutional and individual prevention and support services can be derived.

Risk stratification of perioperative myocardial infarction/injury following noncardiac surgery in high risk patients

Background

Perioperative myocardial infarction/injury (PMI) screening is increasingly recommended by current guidelines. PMI is often caused by type 2 myocardial infarction, and risk stratification tools for these patients are lacking.

Purpose

To derive and internally validate a risk prognostication model for PMI of likely type 2 infarction (lT2MI)

Methods

We included consecutive high-risk patients undergoing noncardiac surgery into this prospective multicenter study. Patients received a systematic routine PMI screening with pre- and postoperative measurement of cardiac troponin (cTn). PMI was prospectively defined as an absolute increase of cTn above the preoperative value. PMI etiology was centrally adjudicated and hierarchically classified by 2 independent physicians based on all clinical information obtained during index hospitalization and selected those with lT2MI for further analyses. To identify risk factors and allow risk stratification in lT2MI, we prespecified that only perioperative variables should be included into the model. We constructed a logistic binary regression model for major adverse cardiac events (MACE) within 120 days, including variables available at time of clinical evaluation: additional symptoms or ECG-criteria required according to the Universal Definition of Myocardial Infarction, absolute increase in cTn (categorized according to level of absolute increase 1–&lt;2 times the 99th percentile, ≥2 to &lt;4 times, and ≥4 times), urgency of procedure, perioperative bleeding (drop in haemoglobin &gt;30g/L or deemed relevant for PMI by adjudicator), and ESC/ESA surgery risk (low, medium, high risk of cardiac events). Variables were omitted from the final model if the p-value was &gt;0.05. Variable levels with similar odds ratios were grouped for simplification of the prognostic model. We constructed a calibration plot and calculated the area under the receiver-operating characteristics curve (AUC) and Brier Score. For internal validation we calculated the predicted probabilities and classified patients into low-risk (predicted event rate &lt;10%), intermediate range (10–20%), and high-risk (&gt;20%), and compared the predicted with the observed event rate.

Results

PMI occurred in 1016/7754 patients (13.1%) of which 750/1016 (73.8%) were adjudicated as lT2MI. MACE within 120 days occurred in 118/750 (15.7%) patients. The initial and final logistic prognostic model for 120-day MACE or death is shown in the table. Internal validation found a good fit of predicted and observed event rate following bootstrapping of 1000 iterations (Figure 1), a good AUC of 0.71 and a Brier score of 0.12.

Conclusion

The derived risk prognostication model for PMI of lT2MI can aid in the stratification of patients and support clinical decision making following noncardiac surgery.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Swiss National Science FoundationSwiss Heart Foundation

Long term outcomes in different aetiologies of perioperative myocardial infarction/injury after noncardiac surgery

Background

Perioperative myocardial infarction/injury (PMI) occurring in the first 48h following noncardiac surgery is a frequent cardiac complication. Better understanding of the underlying aetiologies is urgently needed.

Aim

To explore the association of different aetiologies of PMI with long term outcomes.

Methods

In this prospective multicenter observational study, PMI aetiology was centrally adjudicated and hierarchically classified by two independent physicians based on all information obtained during clinically-indicated PMI work-up including cardiac imaging among consecutive high-risk patients undergoing major noncardiac surgery. PMI aetiology was classified into “extracardiac” if caused by a primarily extracardiac disease such as severe sepsis or pulmonary embolism; and “cardiac”, further subtyped into type 1 myocardial infarction (T1MI), tachyarrhythmia, acute heart failure (AHF), or likely type 2 myocardial infarction (lT2MI). Major adverse cardiac events (MACE) including T1MI, AHF (both only from day 3 to avoid inclusion bias), life-threatening arrhythmia, and cardiovascular death as well as all-cause death were assessed during 365-days follow-up.

Results

PMI occurred in 1016/7754 patients (13.1%). At least one MACE occurred in 684/7754 patients (8.8%) and 818/7754 patients died (10.5%) within 365 days. MACE and all-cause death occurred in 51% (95% CI 31–60) and 38% (95% CI 29–47), 41% (95% CI 28–51) and 27% (95% CI 16–34), 57% (95% CI 41–69) and 40% (95% CI 25–53), 64% (95% CI 45–76) and 49% (95% CI 30–62), as well as 25% (95% CI 22–28%) and 17% (95% CI 14–20) of patients with extracardiac PMI, T1MI, tachyarrhythmia, AHF, and lT2MI, respectively. These associations were confirmed in multivariable analysis.

Conclusion

At 365 days, most PMI aetiologies have unacceptably high rates of MACE and all-cause death, highlighting the urgent need for more intensive treatments.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Swiss National Science FoundationRoche Diagnostics

[Phytotherapeutic treatments of gynecological diseases and fertility disorders in cattle - a veterinary historical analysis]

INTRODUCTION

Fertility problems are the main reasons for culling dairy cows. Diseases of the female genital tract are also often the cause of antibiotic or hormonal treatments in bovine practices. The use of medicinal plants could expand the available therapeutics. The aim of the work was to analyze historical literature before the introduction of antibiotics in veterinary reproductive medicine. Five books in German language, published in Germany and Switzerland between 1878 and 1921, and one handwritten therapy booklet by the rural veterinarian Carl Ammann-Honegger (1879-1960) were systematically examined regarding the descriptions (AW) on gynecological diseases. The herbal and additional ingredients of the recipe, the target animal species, the type of administration and the indication were recorded in detail for each AW. The six literature sources contained a total of 103 AW (79 administered orally, 13 locally, and 11 both orally and locally). Almost two thirds of the AW (61) were based on a mixture of different plants (two to seven plants), and one third of the AW (31) on a single plant. A total of 55 plants were recorded. The most frequently mentioned medical plants were plants of the genus Juniperus (J. communis L. (19 AW), J. sabina L. (13 AW)) and Linum usitatissimum L. (18 AW), Matricaria chamomilla L. (13 AW) and Gentiana lutea L. (12 AW). The treatment of the Retentio secundinarum was the most frequently mentioned indication (44 AW), followed by parturition preparation (17 AW) and endometritis treatment (15 AW). The most frequently recorded plants can be divided based on their ingredients and their effect into (a) energy- and protein-rich forage plants, (b) generally appetizing, digestive- and metabolism-enhancing plants, (c) medical plants with a specific gynecological organotrophic effect and (d) according to current knowledge, predominantly toxic plants. Besides the antimicrobial active immunity to defence against bacterial infections, a stable barrier funcion of the endometrium contributes to uterine health. The plants classified under (a) - (c) have at least the potential for a positive effect on the immune system and the endometrial barrier function and thus contribute indirectly to the uterine health.

Abstract 6257: Mutations in the ASXL1 and ZRSR2 genes are associated with the response to the combination of alvocidib and 5-azacytidine in higher-risk myelodysplastic syndromes

The hypomethylating agent 5-azacytidine (5-Aza) is a standard-of-care for patients with higher-risk myelodysplastic syndromes (MDS). Although an initial response is induced in approximately 50% of 5-Aza treated patients, subsequent relapse is almost certain. Recently, inhibitors of anti-apoptotic BCL-2 protein family members have shown therapeutic potential in acute myeloid leukemia (AML) and higher-risk MDS. Alvocidib (Alv), a CDK9 inhibitor and indirect transcriptional repressor of the anti-apoptotic factor MCL-1, has shown anti-leukemic effects in a phase 1 study of patients with AML (Lee DJ et al, Expert Opin Investig Drugs 2019; Zeidner JF et al, Leuk Res 2015). A phase 1b/2 study with Alv and 5-Aza or decitabine in higher-risk patients with MDS was recently completed (NCT03593915); however, biomarkers for response to the Alv and 5-Aza combination are not well characterized. To identify potential biomarkers of response, we performed a comprehensive in vitro assessment of Alv and 5-Aza combination using a clinically well-characterized cohort of n=45 higher-risk patients with MDS and n=11 healthy controls (HC). CD34+ cells were purified from bone marrow (BM) aspirates using positive selection with MACS beads. CD34+ cells of HC were obtained from femur head replacement surgery bone specimens. After 4 days of expansion in SFEM II medium containing StemSpan Myeloid Expansion Supplement, cells were treated with 5-Aza for 48h, Alv for 24h or their combination (5-Aza for 48h followed by Alv for 24h). Cell viability was determined using CellTiter-Glo (CTG) and Annexin-V apoptosis assays. MCL-1 dependency of MDS samples was assessed using MS1 peptide-based assay. Recurrent myeloid neoplasia mutations in 67 genes were assessed in BM mononuclear cells using NGS panel deep sequencing. The combination of 5-Aza+Alv had an additive cytotoxic effect on CD34+ MDS cells in CTG assay (median cell viability = 74%, 73.8% and 55% for 5-Aza, Alv and combination respectively, p&lt;0.0001). In Annexin-V apoptosis assay, MDS samples were more sensitive to the combination treatment compared to HC (median % of apoptotic and dead cells = 36.6% for MDS vs 25.6% for HC, p=0.0288). MCL-1 dependency inversely and not significantly correlated with CD34+ cell viability in CTG assays (Spearman r=-0.37, p=0.1119). In contrast, we found significant associations between ASXL1 and ZRSR2 mutations and higher sensitivity of MDS samples to 5-Aza+Alv combination (p=0.008 and p=0.0005 in univariable analysis respectively). ZRSR2 mutations also retained an independent impact on cell viability in multivariable analysis (p=0.035). Overall, we provide pre-clinical support for the use of 5-Aza+Alv combination for higher-risk MDS and identified ASXL1 and ZRSR2 mutations as potential genetic biomarkers of augmented response.

Citation Format: Vladimir Ryabov, Nanni Schmitt, Qingyu Xu, Alexander Streuer, Johann-Christoph Jann, Alina Wein, Eva Altrock, Verena Nowak, Nadine Weimer, Julia Obländer, Iris Palme, Ahmed Jawhar, Ali Darwich, Patrick Wuchter, Christel Weiss, Georgia Metzgeroth, Jason M. Foulks, Laurenz Steiner, Mohamad Jawhar, Wolf-Karsten Hofmann, Daniel Nowak. Mutations in the ASXL1 and ZRSR2 genes are associated with the response to the combination of alvocidib and 5-azacytidine in higher-risk myelodysplastic syndromes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6257.

Preclinical evaluation of eltrombopag in a PDX model of myelodysplastic syndromes

Preclinical research of myelodysplastic syndromes (MDSs) is hampered by a lack of feasible disease models. Previously, we have established a robust patient-derived xenograft (PDX) model for MDS. Here we demonstrate for the first time that this model is applicable as a preclinical platform to address pending clinical questions by interrogating the efficacy and safety of the thrombopoietin receptor agonist eltrombopag. Our preclinical study included n = 49 xenografts generated from n = 9 MDS patient samples. Substance efficacy was evidenced by FACS-based human platelet quantification and clonal bone marrow evolution was reconstructed by serial whole-exome sequencing of the PDX samples. In contrast to clinical trials in humans, this experimental setup allowed vehicle- and replicate-controlled analyses on a patient–individual level deciphering substance-specific effects from natural disease progression. We found that eltrombopag effectively stimulated thrombopoiesis in MDS PDX without adversely affecting the patients’ clonal composition. In conclusion, our MDS PDX model is a useful tool for testing new therapeutic concepts in MDS preceding clinical trials.

Cerebrovascular Autoregulation Monitoring in the Management of Adult Severe Traumatic Brain Injury: A Delphi Consensus of Clinicians

BACKGROUND

Several methods have been proposed to measure cerebrovascular autoregulation (CA) in traumatic brain injury (TBI), but the lack of a gold standard and the absence of prospective clinical data on risks, impact on care and outcomes of implementation of CA-guided management lead to uncertainty.

AIM

To formulate statements using a Delphi consensus approach employing a group of expert clinicians, that reflect current knowledge of CA, aspects that can be implemented in TBI management and CA research priorities.

METHODS

A group of 25 international academic experts with clinical expertise in the management of adult severe TBI patients participated in this consensus process. Seventy-seven statements and multiple-choice questions were submitted to the group in two online surveys, followed by a face-to-face meeting and a third online survey. Participants received feedback on average scores and the rationale for resubmission or rephrasing of statements. Consensus on a statement was defined as agreement of more than 75% of participants.

RESULTS

Consensus amongst participants was achieved on the importance of CA status in adult severe TBI pathophysiology, the dynamic non-binary nature of CA impairment, its association with outcome and the inadvisability of employing universal and absolute cerebral perfusion pressure targets. Consensus could not be reached on the accuracy, reliability and validation of any current CA assessment method. There was also no consensus on how to implement CA information in clinical management protocols, reflecting insufficient clinical evidence.

CONCLUSION

The Delphi process resulted in 25 consensus statements addressing the pathophysiology of impaired CA, and its impact on cerebral perfusion pressure targets and outcome. A research agenda was proposed emphasizing the need for better validated CA assessment methods as well as the focused investigation of the application of CA-guided management in clinical care using prospective safety, feasibility and efficacy studies.

Direct comparison of the accuracy of preoperative high-sensitivity cardiac troponin T to predict mortality, acute heart failure and perioperative myocardial infarction/injury after non-cardiac surgery

Background

Death, acute heart failure (AHF) and perioperative myocardial infarction/injury (PMI) are the most relevant cardiovascular complications following non-cardiac surgery. Unfortunately, the incidence of these complications are higher than expected. Currently available tools to predict these complications have only modest accuracy.

Purpose

To determine the accuracy of preoperative high-sensitivity cardiac troponin T (hs-cTnT) concentrations for prediction of mortality, AHF and PMI after non-cardiac surgery.

Methods

We prospectively included 4,709 patients at high cardiovascular risk undergoing non-cardiac surgery. Hs-cTnT concentrations were measured before surgery and, daily after surgery, for two days. PMI was defined as an absolute increase of 14ng/L (the 99th percentile of the assay used) from hs-cTnT baseline values. The primary endpoint was the diagnostic accuracy of preoperative hs-cTnT concentration to predict death, AHF and PMI within 30 days, as quantified by the area under the receiving-operating curve (AUC). Multivariate logistic regression analysis was performed to test the association between preoperative hs-cTnT and each endpoint.

Results

All-cause mortality occurred in 133 (3%), AHF in 84 (2%) and PMI in 742 (16%) patients. Preoperative hs-cTnT concentrations had good accuracy for prediction of death, AHF and PMI (AUC = 0.75 [95% CI, 0.71–0.79], 0.72 [95% CI, 0.67–0.77] and 0.73 [95% CI, 0.71–0.75], respectively). After adjusting for confounders, hs-cTnT remained an independent predictor for death with an adjusted odds ratio (aOR) of 2.1 (95% CI, 1.7–2.7, P&lt;0.001) and for PMI (aOR 2.2, 95% CI, 1.9–2.4, P&lt;0.001), but not for AHF (aOR 1.0, 95% CI, 0.7–1.4, P=0.99). An hs-cTnT concentration below 5ng/L was found in 526 (11%) patients, and this cut-off yielded a negative predictive value of 99.6% for the occurrence of death, 99.2% for AHF and 95.6% for PMI.

Conclusion

The preoperative hs-cTnT concentration has a good accuracy to predict mortality, AHF and PMI after non-cardiac surgery, but is an independent predictor only for mortality and PMI. A cut-off value of 5ng/L identifies a subgroup of patients at low risk for these complications.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Swiss National Foundation, Swiss Herat Foundation

Changes in Working Conditions and Mental Health Among Intensive Care Physicians Across a Decade

Background: International studies have shown that among physicians working in intensive care, a relatively high level of work load, an elevated risk of developing burnout and reduced mental health are frequent. The implementation of a legislative intervention in Germany with the goal to reduce the working hours of physicians, offered an opportunity to investigate the potential influence of occupational conditions on stress and mental health. The present study investigates working conditions, occupational stress and burnout risk in two samples of German Intensive Care Physicians in 2006 and 2016. The aim was to assess how occupational and private stress factors influenced burnout and Effort-Reward-Imbalance indices over this time-period. Methods: Intensive care physicians were surveyed during the annual conference of their profession in two cross-sectional studies (10-year gap). Data on demographic (occupational, family), medical history, and mental health (burnout and Effort-Reward-Imbalance) were assessed by paper pencil questionnaires. Results: In total, N = 2,085 physicians participated (2006: N = 1,403, 2016: N = 695), with N = 1,840 (2006 = 1,248; 2016 = 592) eligible for propensity score matching comparison. In general, more working hours per week and working days on weekends were associated with an increased effort/reward imbalance and higher burnout scores. From 2006 to 2016, reductions in working hours per week and days worked on weekends were accompanied by improvements in occupational stress (Effort-Reward-Imbalance) and by trend in mental health indices (burnout) after matching for differences in working conditions. Conclusions: The study presents the changes concerning occupational stress factors and mental wellbeing in physicians working in intensive care in 2016 as compared to 2006. These findings may promote the implementation of preventive strategies in the vocational context to protect health and productivity of physicians, especially intensive care physicians.

Application of fatigue management systems: small mines and low technology solutions

The impact of fatigue is seen not only in its effect on job performance of haul truck operators but also on the health of the operator and the productivity at the mine site. Its impact can even extend outside of the mine site to the health and well-being of the surrounding community (Fourie et al., 2010). In this paper, a case study of a small surface mining organization is presented. The goal is to highlight the fatigue risk management system implemented at the studied mine site. Mine safety personnel who were interviewed discuss the changes made to the infrastructure of the mine, to administrative areas such as the number of shifts and the use of vacation time, as well as the implementation of new technology into haulage vehicles. This paper reviews how these changes are supported in the research literature.

Directional control-response relationships for mining equipment

A variety of directional control-response relationships are currently found in mining equipment. Two experiments were conducted in a virtual environment to determine optimal direction control-response relationships in a wide variety of circumstances. Direction errors were measured as a function of control orientation (horizontal or vertical), location (left, front, right) and directional control-response relationships. The results confirm that the principles of consistent direction and visual field compatibility are applicable to the majority of situations. An exception is that fewer direction errors were observed when an upward movement of a horizontal lever or movement of a vertical lever away from the participants caused extension (lengthening) of the controlled device, regardless of whether the direction of movement of the control is consistent with the direction in which the extension occurs. Further, both the control of slew by horizontally oriented controls and the control of device movements in a frontal plane by the perpendicular movements of vertical levers were associated with relatively high rates of directional errors, regardless of the directional control-response relationship, and these situations should be avoided. STATEMENT OF RELEVANCE: The results are particularly applicable to the design of mining equipment such as drilling and bolting machines, and have been incorporated into MDG35.1 Guideline for bolting & drilling plant in mines (Industry & Investment NSW, 2010). The results are also relevant to the design of any equipment where vertical or horizontal levers are used to control the movement of equipment appendages, e.g. cranes mounted to mobile equipment and the like.

Bio-sorption of atrazine in the press-cake from oilseeds

Oilseed press-cake (PC) is proposed as a novel material for the removal of hydrophobic organic pollutants (HOPs) from water. Sorption of the pesticides carbaryl, atrazine and parathion, with log K(ow) being, respectively, 1.59, 2.55 and 3.83, was demonstrated using cold-pressed rapeseed (Brassica napus), moringa (Moringa oleifera) and soybean (Glycine max) PCs. Linear sorption isotherms have been observed. The partition coefficient of carbaryl, atrazine and parathion using rapeseed PC were determined to be 0.028+/-0.003, 0.144+/-0.003 and 2.52+/-0.24 L/g, respectively. Partition studies of atrazine in PC-extracted oil and defatted PC showed that the sorption mechanism is mainly through absorption in the residual oil in the PC, whereas adsorption on the PC matrix is quantitatively much less significant. It was also shown that the oil content of the PC is not the only parameter determining the partitioning of pesticides. Indeed, sorption using ground seeds was very weak, as demonstrated by the low partition and mass transfer coefficients. This may be due to cell structures blocking the pesticide diffusion to the oil-containing structures within the seeds, while for PC oil they are present in the form of small (10 microm) droplets trapped within the hydrophilic PC matrix, thus presenting less resistance for mass transfer.

[Lipomatous hypertrophy of the cardiac interatrial septum]

Lipomatous hypertrophy of the interatrial septum (LHIS) is a rare lesion of unknown origin usually diagnosed as an incidental finding during autopsy. It can be associated with supraventricular arrhythmias, venous return obstruction and sudden cardiac death. Five necropsy cases (4 females, 1 male) of LHIS were encountered during the last 31 years; only one case from this series was diagnosed ante mortem. The patients' mean age was 68 years; their mean BMI was 28.4. The mean size of the lesion was 31 mm. In three patients the LHIS was asymptomatic, two patients experienced relapsing multifocal atrial tachycardia and sick sinus syndrome, respectively. Histologically, all cases consisted of a mixture of mature and brown adipose tissue with foci of cardiomyocytes. For a pathologist the knowledge of LHIS is important because of an increasing possibility of its ante mortem diagnosis by imaging methods with a following endomyocardial biopsy, and also because it may appear as a cause of sudden cardiac death.

Concept of "true ICP" in monitoring and prognostication in head trauma

OBJECTIVE

To propose a new coefficient, which contains information about both the absolute ICP and the position of the 'working point' on the pressure-volume curve.

METHOD

ICP was monitored continuously in 187 sedated and ventilated patients. The RAP coefficient was calculated as the running (3 minutes) correlation coefficient between slow changes in pulse amplitude and mean ICP. RAP has value 0 on the flat part of the Pressure-Volume Curve and +1 on the ascending exponential part. Then RAP decreases to zero or becomes negative when ICP increases further and affects cerebrovascular pressure-reactivity (which flattens the pressure-volume curve). Variable tICP = ICP* (1 - RAP) has been called 'trueICP'. It magnifies the critical values of ICP when cerebrovascular reactivity is exhausted and dampens those states where absolute ICP is elevated but vascular reactivity is not affected.

RESULTS

Both Mean ICP and RAP were independently correlated with outcome (ANOVA:ICP-GOS: F = 22; p < 0.00001, RAP-GOS: F = 9; p < 0.001). 'TrueICP' had stronger association with outcome: F = 28; p < 0.000001. Mortality in those patients having 'trueICP' above the threshold of 19 mm Hg was above 80%, while the mortality in those having cICP below 19 mm Hg was only 20% (F = 80; p < 10(-8)). 'TrueICP' was also suitable for continuous monitoring: sustained rise in tICP above 19 mm Hg was strongly associated with fatal complications.

CONCLUSION

The proposed variable is a powerful predictor of fatal outcome following head injury. It is sensitive to both the rising absolute ICP and the critical loss of cerebrovascular regulation.

ICM+: software for on-line analysis of bedside monitoring data after severe head trauma

ICM software was developed in 1986 in Warsaw, Poland and has been in use at the University of Cambridge Neurocritical Care Unit for 10 years collecting data from bed-side monitors in nearly 600 severely head injured patients and calculating secondary indices describing cerebral autoregulation and pressure-volume compensation. The new software ICM+ includes a much extended calculation engine that allows easy configuration and on-line trending of complex parameters. The program records raw signals, and calculates time trends of summary parameters. Configuration and analysis utilises arithmetic expressions of signal processing functions to calculate various statistical properties for each signal, frequency spectrums and derivatives, as well as correlations/cross-correlations between signals. The software allows configuration of several levels of analysis before calculating the final time trends. The final data are displayed in a variety of ways including simple time trends, as well as time window based histograms, cross histograms, correlations etc. All this allows complex information coming off the bed-side monitors to be summarized in a concise fashion and presented to medical and nursing staff in a simple way that alerts them to the development of various pathological processes. The system provides a universal tool for clinical and academic purposes. Its flexibility and advanced signal processing is specialized for the needs of multidisciplinary brain monitoring.

Multi-locus interactions predict risk for post-PTCA restenosis: an approach to the genetic analysis of common complex disease

The complexity of recognizing the potential contribution of a number of possible predictors of complex disorders is increasingly challenging with the application of large-scale single nucleotide polymorphism (SNP) typing. In the search for putative genetic factors predisposing to coronary artery restenosis following balloon angioplasty, we determined genotypes for 94 SNPs representing 62 candidate genes, in a prospectively assembled cohort of 342 cases and 437 controls. Using a customized coupled-logistic regression procedure accounting for both additive and interactive effects, we identified seven SNPs in seven genes that, together, showed a statistically significant association with restenosis incidence (P <0.0001), accounting for 11.6% of overall variance observed. Among them are candidate genes for cardiovascular pathophysiology (apolipoprotein-species and NOS), inflammatory response (TNF receptor and CD14), and cell-cycle control (p53 and p53-associated protein). Our results emphasize the need to account for complex multi-gene influences and interactions when assessing the molecular pathology of multifactorial medical entities.

Strategies for disseminating evidence-based practices to staff who treat people with serious mental illness

Evidence-based practices have not been widely implemented in real-world treatment settings for several reasons, including existing state laws, administrative policies, funding priorities, advocates' concerns, and program staffing. Dissemination strategies focus largely on program staffing and the question of why treatment teams that are responsible for assisting people with serious mental illness fail to use evidence-based practices. In a review of the research literature, two barriers to staff dissemination emerge: individual service providers lack the necessary knowledge and skills to assimilate these practices, and certain organizational dynamics undermine the treatment teams' ability to implement and maintain innovative approaches. Three sets of strategies are useful for overcoming these barriers and fostering dissemination: packaging evidence-based practices so that specific interventions are more accessible and user-friendly to service providers; educating providers about relevant knowledge and skills; and addressing the organizational dynamics of the team to facilitate the implementation of innovations. Research on dissemination is relatively new and is less well developed than the clinical and services research enterprise that has led to evidence-based practices. Implications for future studies are discussed.

Radiosurgery-induced microvascular alterations precede necrosis of the brain neuropil

OBJECTIVE

Radiosurgery is used as a therapeutic modality for a wide range of cerebral disorders. It is important to understand the underlying causes of deleterious side effects that may accompany gamma-irradiation of brain tissue. In this study, structural alterations in rat cerebral vessels subjected to gamma knife irradiation in vivo were examined, for elucidation of their potential role in necrosis formation.

METHODS

A maximal center dose of 75 Gy was delivered to the rat parietal cortex with a 4-mm collimator, and changes occurring before necrosis formation were assessed 3.5 months after irradiation. Transmission electron microscopy, using horseradish peroxidase as a tracer, and scanning electron microscopy with vascular casting were performed.

RESULTS

The capillary network in the irradiated area exhibited thickening and vacuolation of the basement membrane. The capillary density in the irradiated area was lower and the average capillary diameter was larger, compared with the nonirradiated side. These results indicate that substantial changes in the neuropil do not occur 2 weeks before the time of definite necrosis formation, whereas changes in the basement membrane are prominent.

CONCLUSION

The necrotic response to intermediate doses of focused-beam irradiation appears after a considerable latency period and then progresses rapidly. This contrasts with previously reported responses to fractionated whole-brain irradiation, in which damage occurs slowly and gradually. Alterations in the microvascular basement membrane precede overt cellular changes in neuronal and vascular cells and provide an early index of cerebrovascular dysfunction in regions destined to undergo necrosis.

Anticonvulsant effects of gamma surgery in a model of chronic spontaneous limbic epilepsy in rats

OBJECT

The management of intractable epilepsy remains a challenge, despite advances in its surgical and nonsurgical treatment. The identification of low-risk, low-cost therapeutic strategies that lead to improved outcome is therefore an important ongoing goal of basic and clinical research. Single-dose focal ionizing beam radiation delivered at necrosis-inducing and subnecrotic levels was investigated for its effects on seizure activity by using an established model of chronic recurrent spontaneous limbic seizures in rats.

METHODS

A single 90-minute period of repetitive electrical stimulation (inducing stimulus) of the hippocampus in rats elicited a single episode of status epilepticus, followed by a 2- to 4-week seizure-free period. Spontaneous recurrent seizures developed subsequently and persisted for the duration of monitoring (2-10 months). Simultaneous computerized electroencephalography and video recording were used to monitor the animals. After the establishment of spontaneous recurrent seizures, bilateral radiation centered in the ventral hippocampal formation was administered with the Leksell gamma knife, aided by a stereotactic device custom made for small animals. A center dose of 10, 20, or 40 Gy was administered using a 4-mm collimator. Control animals were subjected to the same seizure-inducing stimulus but underwent a sham treatment instead of gamma irradiation. In a second experiment, the authors examined the effects of gamma irradiation on the proclivity of hippocampal neurons to display epileptiform discharges. Naive animals were irradiated with a single 40-Gy dose, as already described. Slices of the hippocampus were prepared from animals killed between 1 and 178 days postirradiation. Sensitivity to penicillin-induced epileptiform spiking was examined in vitro in slices prepared from control and irradiated rat brains.

CONCLUSIONS

In the first experiment, single doses of 20 or 40 Gy (but not 10 Gy) reduced substantially, and in some cases eliminated, behaviorally and electrographically recognized seizures. Significant reductions in both the frequency and duration of spontaneous seizures were observed during a follow-up period of up to 10 months postradiation. Histological examination of the targeted region did not reveal signs of necrosis. These findings indicate that single-dose focal ionizing beam irradiation at subnecrotic dosages reduces or eliminates repetitive spontaneous seizures in a rat model of temporal lobe epilepsy. In the second experiment, synaptically driven neuronal firing was shown to be intact in hippocampal neurons subjected to 40-Gy doses. However, the susceptibility to penicillin-induced epileptiform activity was reduced in the brain slices of animals receiving 40-Gy doses, compared with those from control rats that were not irradiated. The results provide rational support for the utility of subnecrotic gamma irradiation as a therapeutic strategy for treating epilepsy. These findings also provide evidence that a functional increase in the seizure threshold of hippocampal neurons contributes to the anticonvulsant influence of subnecrotic gamma irradiation.

Gamma surgery for hemangiopericytomas

A retrospective analysis of a consecutive series of 12 patients with 15 intracranial hemangiopericytomas treated at the University of Virginia using Gamma surgery is presented. Clinical and radiographic follow up of 3 to 56 months is available for 10 patients with 12 tumors. There was one tumor present at the time of initial Gamma surgery in each patient. Two new tumors occurred in patients previously treated. Nine of the tumors decreased in volume and three remained stable. Four of the nine tumors that shrank later progressed at an average of 22 months after treatment. Of the tumors that decreased in volume and have not progressed, the response has been for an average of 11 months. The follow-up for two tumors that remained unchanged was 10 and 34 months (average 22 months). A third tumor was unchanged at 42 months but the patient died of new disease adjacent to the treated area in the anterior skull base. There were no complications and the quality of life following the procedure was maintained or improved in every case. Gamma surgery is effective in palliating the patients by decreasing tumor volume and delaying recurrence.

Gamma surgery for vein of Galen malformations

OBJECT

The goal of this study was to evaluate the results of gamma surgery in nine patients treated for vein of Galen malformations (VGMs).

METHODS

A consecutive series of nine VGMs in eight children aged 4 to 14 years and in one adult were treated with gamma surgery. Six of the patients were male, including the adult, and three were female. Among these patients there were three Yasargil Type I, one Type II, two Type III, and three Type IV malformations. Previous embolization had failed in four cases. Three VGMs were treated with gamma surgery twice. An additional patient with a Type III VGM underwent stereotactic angiography in preparation for gamma surgery but was judged to be suitable for direct embolization. Follow-up angiograms were obtained in eight of the VGMs treated. Four no longer filled; one has probably been obliterated, but this cannot be confirmed because the patient refused to undergo final angiography; one patient has residual fistulas not included in the initial treatment field, which were retreated recently; and two other patients have marked reduction of flow through their VGMs.

CONCLUSIONS

Gamma surgery is a viable option in the treatment of VGMs in clinically stable patients. Combined endovascular therapy and gamma surgery is of benefit in complex malformations.

Gamma surgery for vestibular schwannoma

OBJECT

The goal of this study was to assess the results of gamma surgery (GS) for vestibular schwannoma (VS) in 200 cases treated over the last 10 years and to review the role of this neurosurgical procedure in the management of VS.

METHODS

Follow-up reviews ranging from 1 to 10 years were available in 153 of these patients. Follow-up images in these cases were analyzed using computer software that we developed to obtain volume measurements for the tumors, and the clinical condition of the patients was assessed using questionnaires. Gamma surgery was the primary treatment modality in 96 cases and followed microsurgery in 57 cases. Tumors ranged in volume from 0.02 to 18.3 cm(3). In the group in which GS was the primary treatment, a decrease in volume was observed in 78 cases (81%), no change in 12 (12%), and an increase in volume in six cases (6%). The decrease was more than 75% in seven cases. In the group treated following microsurgery, a decrease in volume was observed in 37 cases (65%), no change in 14 (25%), and an increase in volume in six (11%). The decrease was more than 75% in eight cases. Five patients experienced trigeminal dysfunction; in three cases this was transient and in the other two it was persistent, although there has been improvement. Three patients had facial paresis (in one case this was transient, lasting 6 weeks; in one case there was 80% recovery at 18 months posttreatment; and in one case surgery was performed after the onset of facial paresis for presumed increase in tumor size). Over a 6-year period, hearing deteriorated in 60% of the patients. Three patients showed an improvement in hearing. No hearing deterioration was observed during the first 2 years of follow-up review.

CONCLUSIONS

Gamma surgery should be used to treat postoperative residual tumors as well as tumors in patients with medical conditions that preclude surgery. Microsurgery should be performed whenever a surgeon is confident of extirpating the tumor with a risk-benefit ratio superior to that presented in this study.

Gamma surgery for intracranial metastases from renal cell carcinoma

OBJECT

The goal of this study was to evaluate the effectiveness and limitations of gamma surgery (GS) in the treatment of renal cell carcinoma that has metastasized to the brain.

METHODS

The authors performed a retrospective analysis of a consecutive series of 21 patients with 37 metastatic brain deposits from renal cell carcinoma who were treated with GS at the University of Virginia from 1990 to 1999. Clinical data were available in all patients. No patient died of progression of intracranial disease or deteriorated neurologically following GS. Eight patients clinically improved. Follow-up imaging studies were available for 23 tumors in 12 patients. Nine patients did not undergo follow-up imaging. One patient lived 17 months and succumbed to systemic disease: no brain imaging was performed in this case. Another patient refused further imaging and lived 7 months. Seven patients lived up to 4 months after the procedure; however, their physicians did not require these patients to undergo follow-up imaging examinations because of their general conditions-all had systemic progression of disease. Of the 23 tumors that were observed posttreatment, one remained unchanged in volume, 16 decreased in volume, and six disappeared. No tumor progressed at any time, and there were no radiation-induced changes on follow-up imaging an average of 21 months after GS (range 3-63 months).

CONCLUSIONS

Gamma surgery provides an alternative to surgical resection of metastatic brain deposits from renal cell carcinoma. Neurological side effects were seen in only one case; freedom from progression of disease was achieved in all cases.

Radiosurgery for cavernous malformations

OBJECT

The authors examined 22 patients with cavernous malformations (CMs) who had undergone gamma knife radiosurgery (GKRS) to assess the value of this procedure in treating these lesions.

METHODS

At the Karolinska Hospital, GKRS was used to treat 23 patients with CMs during the period of 1985 through 1996. One of the patients was lost to follow up and the treatment results of the 22 remaining patients were analyzed. In the first half of the series, the CMs were treated with high doses of radiation (> 15-Gy dose to the periphery); in the second half of the series, lower doses were used. Nine of the 22 patients suffered a post-GKRS hemorrhage and six developed a radiation-induced complication (two of these patients experienced both). Some time after GKRS was performed, surgical removal of the CM had to be undertaken in four patients because of hemorrhage and in two patients because of radiation-induced complications. Four of the nine patients who experienced no post-GKRS hemorrhage or radiation-induced complication were treated before 1990; recent magnetic resonance imaging revealed a decrease in the size of the CM in three of these individuals and no size change in the other. The annual post-GKRS hemorrhage rate was 8% in this group. There was a trend in the hemorrhage rate to decrease 4 years postsurgery. There was also a trend for higher radiation doses administered to the periphery of the lesion to result in a lower risk of posttreatment hemorrhage. However, it could not be concluded whether GKRS affects the natural course of a CM. The incidence of radiation-induced complications was approximately seven times higher than that expected if the same number of patients had been treated by GKRS with the same radiation dose distributions for arteriovenous malformations instead of CMs.

CONCLUSIONS

The high incidence of radiation-induced complications does not seem to justify the limited protection the treatment may afford in only exceptional cases. A prospective randomized study is needed before the role of radiosurgery in the management of these lesions can be defined. Until such a study has proved differently, a caveat must be raised for the treatment of CM with GKRS.

Gamma knife surgery for previously irradiated arteriovenous malformations

OBJECTIVE

The goal was to report the treatment results after a second gamma knife treatment and to compare them with the results obtained after a first gamma knife treatment, as well as to investigate whether the models to predict the results after a first treatment are also applicable after gamma knife treatment of previously irradiated arteriovenous malformations.

METHODS

The number of complications and the posttreatment hemorrhage rate were recorded for 112 patients in the study, and the number of obliterations was recorded for the 101 patients for whom conclusive angiograms were obtained. The results were compared with the expected results after a first gamma knife treatment.

RESULTS

The observed number of obliterations was 62, which is not significantly different from the predicted number of 65. There were 14 observed and 5 predicted complications. When the risk from the preceding radiation treatment was added, the observed number of complications was similar to the predicted number. Six hemorrhages were observed after the second treatment. Of the 5 patients with unchanged arteriovenous malformation size after both the first and second treatments, 2 experienced hemorrhages after the second treatment, compared with none among the 81 patients for whom the malformation was obliterated or significantly decreased in size after the second treatment.

CONCLUSIONS

The obliteration rate after gamma knife surgery for previously irradiated arteriovenous malformations is similar to that after primary gamma knife treatment. The complication rate increases with the amount of radiation previously given. The incidence of posttreatment hemorrhages is lower in the latency period if the malformation is affected by the radiation.

[Frequency and etiology of calf losses and calf diseases in cow-calf farms. III. seroprevalence of selected diseases and prevalence of endoparasites and weaning age]

In a cross sectional study in 38 cow-calf farms blood and fecal samples were taken from 207 calves at an age of 8-10 months and their darms, in order to determine the seroprevalence of Leptospira hardjo, Coxiella burnetii, Toxoplasma gondii and the presence of the BVD-Antigen as well as the prevalence of endoparasites. The study was conducted in fall 1994 at the end of the grazing period. Eggs or larvaes of gastrointestinal helminths were detected in 74% of calves that were dewormed before the grazing period and in 88% of untreated calves. The difference between the two groups was statistically significant. In 83% of the weaned calves oocysts of Eimeria spp. were diagnosed. No significant difference in weight gain was observed between animals without endoparasites and animals infected with either helminths and/or Eimeria. In cows the prevalence was 61.5% for helminths and 45.7% for Eimeria spp. In calves the seroprevalence was 4% for Leptospira hardjo, 0.5% for Coxiella burnetii and 14.0% for Toxoplasma gondii. The seroprevalence in cows were 18% for Leptospira hardjo, 7.6% for Coxiella burnetii and 14.3% for Toxoplasma gondii. The prevalence of the BVD-Virus antigen was 0.5% for calves and cows.

Annual risk for the first hemorrhage from untreated cerebral arteriovenous malformations

To estimate the annual risk for the first hemorrhage, survival and life table statistics were used to analyze data from 2262 patients with cerebral arteriovenous malformations (AVM). We found that the risk for hemorrhage increases with increasing age. A validity test revealed, however, that life table statistics used on the total patient material underestimated the annual risk for hemorrhage, especially for patients 20-50 years of age. A method based on the fact that the distribution of the time at risk until the initial hemorrhage (= age at first rupture) reflects the risk for hemorrhage in untreated AVM was therefore also employed. The analysis yielded three conclusions: 1) the annual risk of hemorrhage increases with age; 2) small AVM are less prone to rupture; and 3) the risk of hemorrhage is higher in women during their fertile years as compared to males in the same age group. The risk related to age, AVM size and location assessed by survival statistics in the subgroup of patients with a known date for the initial hemorrhage gave similar results.

Six new DPB1 alleles identified in a study of 1,302 unrelated bone marrow donor-recipient pairs

Six new DPB1 alleles were identified by PCR-SSOP methodologies in the course of a retrospective study of the role of HLA matching in the outcome of unrelated donor bone marrow transplantation. Sequencing confirmed that five of these alleles (DPB1*5901, *6801, *7101, *7201, and *7301) represent novel combinations of previously described sequence motifs in the variable regions of DPB1; the sixth (DPB1*7001) appears to result from a novel point mutation. These data support previous observations which suggest that multiple mechanisms, including segmental exchange and mutation, appear to be responsible for generating sequence diversity at the DPB1 locus. The extremely low discrepancy rate of 0.1% between the two laboratories which typed the samples, and the ability to predict the new sequences from probe hybridization patterns, indicate that SSOP is an accurate and efficient method for studying polymorphism at DPB1.

[Frequency and etiology of calf losses and calf diseases before weaning in cow-calf farms. II. Microbiological and parasitological diagnoses in diarrheic calves]

Diarrhea is the most frequently diagnosed disease in Swiss cow-calf farms. During an longitudinal study conducted in 105 cow-calf farms in Switzerland in 1993-95, blood and fecal samples were collected from diarrheic calves and from calves that died because of diarrhea. Campylobacter spp. were detected in 42%, E. coli (VTEC) in 32%, rotavirus in 33%, coronavirus in 13%, coccidia in 43% and helminths in 8% of the cases. In some samples Yersinia pseudotuberculosis were isolated. The BVD-virus antigen was not detected in any of the calves examined. In most cases concurrent infection with several enteropathogens was diagnosed. Specific causes of diarrhea were therefore difficult to establish. The bacteriological findings of this study have implication for food safety: VTEC, Campylobacter spp. Yersinia spp. and cryptosporidia are considered as potential causes on zoonoses.

Calf health in cow-calf herds in Switzerland

In 1993, an observational study was initiated to provide general information on animal health in extensive beef farms, to estimate disease frequency and the economic impact of calf diseases and to identify risk factors related to health and weight gain. The longitudinal study was conducted from fall 1993 until winter 94/95 and included 100 farms in western Switzerland. The basic concept was to follow one generation of calves on these farms and record all events concerning animal health from birth to weaning. The study population included 1270 calves (most were Angus crossbreds). Farm-management data were collected with a questionnaire conducted on the farm. Birth and weaning weights were obtained from the beef cattle breeding association. Clinical diagnoses and treatment costs were provided by the farm veterinarians. Two thirds of the dead calves were submitted to a complete postmortem examination. Fifty-three percent of the farms in the study were primary type income farms while 47% were secondary type income farms. Thirty-eight percent of the farms were situated in the lower areas of Switzerland, 14% in the prealpine foothills, the remaining 48% were located in mountain areas. Preweaning calf mortality was 5%. The main causes of calf deaths were respiratory diseases and digestive disorders. Twenty-two percent of the calves were treated at least once by a veterinarian; 36% of the treatments administered by the veterinarian were applied because of diarrhea, 27% because of respiratory diseases. Disease incidence was highest during the months of November, December and January. The association of disease and potential farm-level risk factors was analysed using chi 2-statistics and multivariable regression methods including generalized estimating equations to adjusted for herd effects. Specific risk factors for disease were not identified. Treatment for disease was not associated with 250-day standardized weight gain.

[Frequency and etiology of calf losses and calf diseases in cow-calf farms. I. Methods of data collection, calf mortality, and calf morbidity]

An observational study was initiated to provide general information on calf health and estimates of frequency and of economic impact of calf diseases in farms with extensive beef production. The study was planned as a cohort study and included all calves born during the calving season of 1993/94 in 105 cow-calf farms in western Switzerland. The total preweaning mortality was 8.5% (123 calves out of 1452 calvings); 2.5% of the calves were stillborn, and 6.0% died or were euthanized before weaning. Forty-four percent of all losses were recorded in the perinatal period (i.e. the first 48 hours p. p.). The average preweaning mortality among liveborn calves at farm level was 6.1%. A large variation in mortality was observed from farm to farm (0-50%). In 50% of the post mortem analyses, respiratory disease was diagnosed as the cause of death. Twenty-two percent of all calves were treated at least once by a veterinarian. Thirty-six percent of all treatments were performed because of diarrhea, 26% because of respiratory disease and 15% because of umbilical problems. From birth to weaning age, the average treatment costs including calving assistance, medication and prophylactic measures were SFr, 23.80 per calf.

Prediction of obliteration after gamma knife surgery for cerebral arteriovenous malformations

OBJECTIVE

To define the factors of importance for the obliteration of cerebral arteriovenous malformations (AVMs), thus making a prediction of the probability for obliteration possible.

METHODS

In 945 AVMs of a series of 1319 patients treated with the gamma knife during 1970 to 1990, the relationship between patient, AVMs, and treatment parameters on the one hand and the obliteration of the nidus on the other was analyzed.

RESULTS

The obliteration rate increased both with increased minimum (lowest periphery) and average dose and decreased with increased AVM volume. The minimum dose to the AVMs was the decisive dose factor for the treatment result. The higher the minimum dose, the higher the chance for total obliteration. The curve illustrating this relation increased logarithmically to a value of 87%. A higher average dose shortened the latency to AVM obliteration. For the obliterated cases, the larger the malformation, the lower the minimum dose used. This prompted us to relate the obliteration rate to the product minimum dose (AVM volume)1/3 (K index). The obliteration rate increased linearly with the K index up to a value of approximately 27, and for higher K values, the obliteration rate had a constant value of approximately 80%. For the group of 273 cases treated with a minimum dose of at least 25 Gy, the obliteration rate at the study end point (defined as 2-yr latency) was 80% (95% confidence interval = 75-85%). If obliterations that occurred beyond the end point are included, the obliteration rate increased to 85% (81-89%).

CONCLUSION

The probability of obliteration of AVMs after gamma knife surgery is related both to the lowest dose to the AVMs and the AVM volume, and it can be predicted using the K index.

Radiosurgery for cerebral AVMs in children and adolescents: the neurobehavioral outcome

Eight patients, ranging in age from 9 to 18 years, were treated for arteriovenous malformations using gamma knife radiosurgery and were evaluated an average of 6 years after treatment to record potential effects of radiosurgery on cognitive and neuropsychological performance. Tests for general intelligence, nonverbal intelligence, memory and its components, and attention performance were administered to patients and compared with test results of age-matched siblings or first cousins. No statistically significant difference was found between the performance of patients and controls in any of the tests administered. Additionally, a specially designed questionnaire completed by the patients, their parents, and their teachers revealed that the patients' emotional and relational behavior was stable and unchanged after treatment. No correlation was found between the neurocognitive test performance and the lesion volumes irradiated, but the lesion site was found to contribute to the type of deficit recorded after treatment. The less invasive nature of the radiosurgical approach, combined with the brevity or absence of hospitalization, presumably contributed to the patients successful physical, mental, and emotional recovery.

Endothelial cells as cytotoxic effector cells: cytokine-activated rat islet endothelial cells lyse syngeneic islet cells via nitric oxide

In vivo, each beta cell is located in proximity to at least one capillary islet endothelial cell. Rat aorta and islet endothelial cells can be activated in vitro to express inducible nitric oxide synthase by a cytokine mixture of tumour necrosis factor-alpha, gamma-interferon, and interleukin-1 beta and to produce high concentrations of nitric oxide. We have performed co-culture experiments with rat islet endothelial cells together with isolated syngeneic islet cells at low target:effector ratios with or without previous cytokine challenge of endothelial cultures. Co-cultures were always free of exogenous cytokines, which were removed prior to addition of islet cells. We found that pre-activated, in contrast to resident islet endothelial cells, at a target:effector ratio as low as 1:1 almost completely lysed syngeneic beta and non-beta cells with 24 h of co-culture. Lysis by pre-activated islet endothelial cells was found to be preceded by DNA damage found in 46% of islet cells after 8 h of co-culture with pre-activated vs 7% with resting islet endothelial cells. Lysis was blocked to control levels in the presence of the nitric oxide synthase inhibitor NG-methyl-L-arginine. With the results presented here, we demonstrate for the first time, that activated endothelial lining cells can express effector cell activity and thus can contribute to local tissue destruction, especially in organs that are densely capillarized such as pancreatic islets.

Accuracy of an experimental stereotactic system for MRI-based gamma knife irradiation in the rat

Stereotactic devices for experimental Gamma Knife irradiation and magnetic resonance imaging (MRI) have recently been developed for experimental studies using rats [6,7]. The present study examined the accuracy of these devices using the following two approaches. In the first approach, Gamma Knife irradiation was performed using the stereotactic device with targets based on a standard stereotactic atlas. Gadolinium-enhanced T1-weighted magnetic resonance imaging was performed using the MRI stereotactic device. Animals were then sacrificed after Evans blue injection, and the rat brain was sliced using an attachment to the stereotactic device. The center coordinates of the gadolinium-enhanced area from the MRI and Evans blue-stained area from the tissue sections were obtained using a computer-assisted image analysis system. These coordinates were compared with the target coordinates planned from the stereotactic atlas. In the second approach, a thermoluminescence dosimeter was implanted in the rat brain. Stereotactic MRI was performed using the stereotactic MRI device, and the coordinates of the implant were obtained. Gamma Knife irradiation was then performed at this target using the stereotactic device. The absorbed dose was measured and compared with the planning dose. These experiments demonstrated a spatial error of 0.6 mm (standard error +/- 0.07) between Gamma Knife irradiation based on a comparison of the atlas coordinates and the lesion, and a spatial error of 1.0 mm (standard error +/- 0.13) based on a comparison of the stereotactic MR images and the lesion. Gamma Knife irradiation based on MR images using the stereotactic device demonstrated a maximum error of 10% in absorbed dose at the target center. Together, the stereotactic devices for Gamma Knife irradiation and magnetic resonance imaging provide useful tools for Gamma Knife research in an animal model.