Deep hybrid modeling of a HEK293 process: Combining long short-term memory networks with first principles equations

The combination of physical equations with deep learning is becoming a promising methodology for bioprocess digitalization. In this paper, we investigate for the first time the combination of long short-term memory (LSTM) networks with first principles equations in a hybrid workflow to describe human embryonic kidney 293 (HEK293) culture dynamics. Experimental data of 27 extracellular state variables in 20 fed-batch HEK293 cultures were collected in a parallel high throughput 250 mL cultivation system in an industrial process development setting. The adaptive moment estimation method with stochastic regularization and cross-validation were employed for deep learning. A total of 784 hybrid models with varying deep neural network architectures, depths, layers sizes and node activation functions were compared. In most scenarios, hybrid LSTM models outperformed classical hybrid Feedforward Neural Network (FFNN) models in terms of training and testing error. Hybrid LSTM models revealed to be less sensitive to data resampling than FFNN hybrid models. As disadvantages, Hybrid LSTM models are in general more complex (higher number of parameters) and have a higher computation cost than FFNN hybrid models. The hybrid model with the highest prediction accuracy consisted in a LSTM network with seven internal states connected in series with dynamic material balance equations. This hybrid model correctly predicted the dynamics of the 27 state variables (R2 = 0.93 in the test data set), including biomass, key substrates, amino acids and metabolic by-products for around 10 cultivation days.

Quality of life in patients and caregivers after aneurysmal subarachnoid hemorrhage: a Flemish population study

Background and aims

Aneurysmal subarachnoid hemorrhages (aSAH) have high mortality and morbidity. However, the impact on Quality of Life (QoL) of patients remains poorly documented, and data on primary caregiver burden is even scarcer.

Methods

This is a single center, cross-sectional study performed at the Antwerp University Hospital, Belgium. We included aSAH patients during follow-up at the outpatient clinic and assessed the QoL, by using the Stroke Specific Quality of Life scale (SSQoL). Caregiver burden was evaluated by the Caregiver Strain Index (CSI). The aSAH severity and functional outcome (at 90 days) were assessed, respectively, by mFisher score and modified Ranking Scale (mRS). Statistical analysis was performed using SPSS version 27.

Results

In total, 22 aSAH patients were included, on average 15.5 (range 4–45) months after the aSAH. The SSQoL score was 3.7 ± 0.7, with a mean psychosocial domain score of 3.2 ± 0.8 and physical domain of 4.2 ± 0.8. Psychosocial factors, especially decreased energy levels and cognitive impairment, had a negative impact on the QoL (p = 0.02 en p = 0.05). No association was found between QoL and mFisher, nor between QoL and mRS. Fifteen primary caregivers completed the CSI. Only 3 (20%) of them reported a high care burden (CSI > 6), although changes in daily life and personal plans were reported, respectively, by 73% (n = 11) and 67% (n = 10) of caregivers. We only found a correlation between the mFisher score and CSI (p = 0.01).

Conclusion

Our results emphasize that there is an important psychosocial impact on the QoL of patients after aSAH, and their primary caregivers. More research is warranted.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13760-022-02085-x.

Successful conservative managements of extensive pneumatoceles in a preterm girl: A case report

We describe a preterm girl with severe respiratory distress syndrome, which was managed with mechanical ventilation. She developed severe ventilator induced lung injury, causing extensive unilateral emphysema. CT-scan of the lungs corresponded with extensive pneumatoceles. She was managed conservatively, using neurally adjusted ventilatory assist, with success and was extubated on day of life 38. She was discharged home without any respiratory support at 39 weeks of postmenstrual age. Our case illustrates the ongoing risk of severe ventilator induced lung injury and highlights a unique injury pattern in a preterm newborn that was managed conservatively using neurally adjusted ventilatory assist with an excellent outcome.

Combining quantitative and qualitative approaches to determine viability of a potential Salmonella Typhimurium vaccination program in pigs in Belgium

Vaccinating pigs against Salmonella Typhimurium (ST) might be a way to control ST infections at farm level and reduce human infections. Two main issues have to be addressed before such a mandatory vaccination program can be implemented: the effective reduction of attributable human incidence has to be demonstrated and all socio-economic barriers impacting the attitude and motivation of the pig sector have to be lifted. The present research used a quantitative microbial risk assessment model to estimate the effect of different hypothetical Salmonella spp. and ST mitigation strategies on the annual prevalence of human salmonellosis along the minced pork production chain. In addition, a qualitative study aimed to list the potential concerns of the pig sector about the implementation of a hypothetical future vaccination program. The following themes were the most often mentioned: awareness, vaccine cost-benefit/effectiveness, legislation, monovalent vaccine, time and labour required to vaccinate, vaccine registration and trade restriction. Cost-effectiveness and cost-benefit of vaccination were cited by all the key interviewees (n = 12). However, based on the quantitative microbial risk assessment model, vaccination alone may not be sufficiently effective to reduce the annual human salmonellosis prevalence. A combination of different control measures along the food chain, with a special focus on interventions at the slaughterhouse, might be more effective in achieving the desired goal than vaccination alone.

Evaluation of group vaccination of sows and gilts against Salmonella Typhimurium with an attenuated vaccine in subclinically infected pig herds

Subclinical Salmonella Typhimurium infections occur frequently in pigs and constitute a major risk for human salmonellosis. With the currently available control measures, Salmonella Typhimurium infections in pigs remain difficult to control. Vaccination has been proposed to be an effective tool to control infections at farm level. In the current study, the effect of group vaccination of sows and gilts against Salmonella Typhimurium is evaluated on Salmonella prevalence in fecal and overshoe samples and ileocecal lymph nodes, and on serology in the sows and their offspring in three subclinically infected pig farms. In each farm, all sows and gilts were vaccinated twice, three weeks apart, with an attenuated histidine-adenine auxotrophic vaccine (Salmoporc®, IDT Biologika). From three months after the group vaccination onwards, all sows were given a booster dose three weeks before every farrowing. The farms were monitored bacteriologically and serologically from 12 months before until 15 months after the group vaccination. After group vaccination, no significant effect was detected in the prevalence of Salmonella Typhimurium in the fecal and overshoe samples collected in the sows (before: 2 %, after: 0 %) and their offspring at 18 weeks (before: 17 %, after: 11 %) and at 26 weeks of age (before: 15 %, after: 7 %), and when combining the results of the offspring at 18 and 26 weeks of age (before: 16 %, after: 9 %). Also, no significant effect was detected in the prevalence of Salmonella Typhimurium positive lymph nodes of sows (before and after: 0 %) and their offspring (before: 4 %, after: 7 %). Regarding serology, the mean S/P-ratios of the sows were significantly higher after the group vaccination, compared to before group vaccination (before: 1.50, after: 2.32, p < 0.001). The mean S/P-ratios of the offspring at slaughter age were significantly lower after the group vaccination, compared to before group vaccination (before: 1.71, after: 1.04, p = 0.001). In conclusion, group vaccination of sows and gilts resulted in a more beneficial serological status of the offspring, but did not significantly decrease Salmonella Typhimurium excretion and lymph node contamination.

Diagnostic and (new) therapeutic options for resistant hypertension: a short review

Hypertension is a major risk factor for ischaemic heart disease and stroke. Despite the availability of numerous pharmacological treatment options, blood pressure (BP) targets are often not achieved. The inability to reach BP levels below 140/90 mmHg despite the use of three or more antihypertensive drugs is defined as resistant hypertension (RH). The etiology for RH is multifactorial. First, BP should be appropriately measured. In order to improve BP control, lifestyle modification should be recommended, adherence should be carefully assessed to exclude pseudo-resistance, and efforts should be made to exclude secondary causes of hypertension before initiating new drugs or considering device-based treatment strategies. This short review will highlight several aspects of RH management along with a focus on several new treatment options. act available.

Effect of aquifer storage and recovery (ASR) on recovered stormwater quality variability

Aquifer Storage and Recovery (ASR) is increasingly being considered as a means of reusing urban stormwater to supplement available urban water resources. Storage of stormwater in an aquifer has been shown to affect water quality but it has also been claimed that storage will also decrease the stormwater quality variability making for improved predictability and management. This study is the first to document the changes in stormwater quality variability as a result of subsurface storage at four full scale ASR sites using advanced statistical techniques. New methods to examine water quality are required as data is often highly left censored and so traditional measures of variability such as the coefficient of variation are inappropriate. It was observed that for some water quality parameters (most notably E. coli) there was a marked improvement of water quality and a significant decrease in variability at all sites. This means that aquifer storage prior to engineered treatment systems may be advantageous in terms of system design to avoid over engineering. For other parameters such as metal(loids)s and nutrients the trend was less clear due to the numerous processes occurring during storage leading to an increase in variability, especially for geogenic metals and metalloids such as iron and arsenic. Depending upon the specific water quality parameters and end use, use of ASR may not have a dampening effect on stormwater quality variability.

Universal Fermi liquid crossover and quantum criticality in a mesoscopic system

Quantum critical systems derive their finite-temperature properties from the influence of a zero-temperature quantum phase transition. The paradigm is essential for understanding unconventional high-Tc superconductors and the non-Fermi liquid properties of heavy fermion compounds. However, the microscopic origins of quantum phase transitions in complex materials are often debated. Here we demonstrate experimentally, with support from numerical renormalization group calculations, a universal crossover from quantum critical non-Fermi liquid behaviour to distinct Fermi liquid ground states in a highly controllable quantum dot device. Our device realizes the non-Fermi liquid two-channel Kondo state, based on a spin-1/2 impurity exchange-coupled equally to two independent electronic reservoirs. On detuning the exchange couplings we observe the Fermi liquid scale T*, at energies below which the spin is screened conventionally by the more strongly coupled channel. We extract a quadratic dependence of T* on gate voltage close to criticality, and validate an asymptotically exact description of the universal crossover between strongly correlated non-Fermi liquid and Fermi liquid states.

Molecular determinants of positive allosteric modulation of the human metabotropic glutamate receptor 2

BACKGROUND AND PURPOSE

The activation of the metabotropic glutamate receptor 2 (mGlu2 ) reduces glutamatergic transmission in brain regions where excess excitatory signalling is implicated in disorders such as anxiety and schizophrenia. Positive allosteric modulators (PAMs) can provide a fine-tuned potentiation of these receptors' function and are being investigated as a novel therapeutic approach. An extensive set of mutant human mGlu2 receptors were used to investigate the molecular determinants that are important for positive allosteric modulation at this receptor.

EXPERIMENTAL APPROACH

Site-directed mutagenesis, binding and functional assays were employed to identify amino acids important for the activity of nine PAMs. The data from the radioligand binding and mutagenesis studies were used with computational docking to predict a binding mode at an mGlu2 receptor model based on the recent structure of the mGlu1 receptor.

KEY RESULTS

New amino acids in TM3 (R635, L639, F643), TM5 (L732) and TM6 (W773, F776) were identified for the first time as playing an important role in the activity of mGlu2 PAMs.

CONCLUSIONS AND IMPLICATIONS

This extensive study furthers our understanding of positive allosteric modulation of the mGlu2 receptor and can contribute to improved future design of mGlu2 PAMs.

Time interval between maternal electrocardiogram and venous Doppler waves in normal pregnancy and preeclampsia: a pilot study

PURPOSE

To evaluate the time interval between maternal electrocardiogram (ECG) and venous Doppler waves at different stages of uncomplicated pregnancy (UP) and in preeclampsia (PE).

MATERIALS AND METHODS

Cross-sectional pilot study in 40 uncomplicated singleton pregnancies, categorized in four groups of ten according to gestational age: 10 - 14 weeks (UP1), 18 - 23 weeks (UP2), 28 - 33 weeks (UP3) and ≥ 37 weeks (UP4) of gestation. A fifth group of ten women with PE was also included. A Doppler flow examination at the level of renal interlobar veins (RIV) and hepatic veins (HV) was performed according to a standard protocol, in association with a maternal ECG. The time interval between the ECG P-wave and the corresponding A-deflection of the venous Doppler waves was measured (PA), and expressed relative to the duration of the cardiac cycle (RR), and labeled PA/RR.

RESULTS

In hepatic veins, the PA/RR is longer in UP 4 than in UP 1 (0.48 ± 0.15 versus 0.29 ± 0.09, p ≤ 0.001). When all UP groups were compared, the PA/RR increased gradually with gestational age. In PE, the HV PA/RR is shorter than in UP 3 (0.25 ± 0.09 versus 0.42 ± 0.14, p < 0.01) and this difference persisted under anti-hypertensive treatment (0.28 ± 0.06 versus 0.42 ± 0.14, p ≤ 0.01, n = 6). Similar results were found in both kidneys. In UP 1 but not in UP 3 or UP 4, the HV PA/RR is shorter in the liver than in the left and right kidney (0.29 ± 0.09 versus 0.38 ± 0.12, p < 0.01, and versus 0.36 ± 0.09, p ≤ 0.01).

CONCLUSION

The PA/RR is organ-specific and gestation-dependent, and is considered to relate to venous vascular tone and/or intravascular filling. Increased values at advanced gestational stages are consistent with known features of maternal cardiovascular adaptation. Shorter values in preeclampsia are consistent with maternal cardiovascular maladaptation mechanisms. Our pilot study invites more research of the relevance of the time interval between maternal ECG and venous Doppler waves as a new parameter for studying the gestational cardiovascular (patho)physiology of the maternal venous compartment by duplex sonography.

OS095. Impedance cardiography: A straightforward and reliable tool to evaluate differences of cardiac reflex response between normal pregnancy and pre-eclampsia

INTRODUCTION

Reflex responses of cardiac cycle time intervals (CCTI) can be measured by echocardiography, and are reported to differ between uneventful pregnancy (UP) and pre-eclampsia (PE). It is unknown whether impedance cardiography (ICG) is a useful method to measure CCTI during pregnancy.

OBJECTIVES

ICG measurements of CCTI before and after orthostatic challenge are evaluated in UP and in the clinical phase of PE.

METHODS

Examinations were performed twice in 16 UP (30-36 weeks), and once in 30 early PE (EPE, <34 weeks) and in 32 late PE (LPE, ⩾34 weeks). A 3rd generation ICG device using a 4 electrode arrangement (NICCOMO, Medis, Germany) was used to measure CCTI in supine position and after moving to upright position. The pre-ejection period (PEP) is the time-interval between ventricular depolarisation and start of aortic flow. The left ventricular ejection time (LVET) is the time-interval between opening and closing of the aortic valve. Diastolic time (DT) is heart period duration - (PEP+LVET). Orthostatic-induced changes from supine to upright position (cardiac reflex response or CRR) were evaluated using One-sample Wilcoxon Signed Rank Tests. All CRRs in EPE and LPE were compared to UP using Mann-Whitney U tests. Data are represented as medians (interquartile ranges).

RESULTS

Maternal age was comparable between all groups [29 (26-32) years; p⩾0.47]. Gestational age was comparable between both early [31 (28-32) vs 31 (27-33) weeks] and late [37 (36-39) vs 38 (36-39) weeks] third trimester UP and PE [p⩾0.38]. Pre-gestational BMI was higher in EPE compared to UP [26 (24-32) vs 23 (21-24); p<0.01]. This was not true for LPE [25 (23-28); p=0.06]. Birth weight percentiles were lower in both EPE and LPE compared to UP [UP: 44 (38-78), EPE: 18 (5-28), LPE: 31 (18-59); p<0.05], and also lower in EPE compared to LPE [p=0.03]. CRRs within each group are shown in Table 1. The CRRs of PEP were significantly different between UP and both EPE and LPE [p⩽0.01], due to orthostatic-induced increase in PE but not in UP .

CONCLUSION

Our study confirms that orthostasis does not change PEP in UP but induces a significant increase of PEP in PE. The increased reflex-induced duration of isovolumetric contraction time can be explained by a decreased left ventricular performance in the clinical phase of PE as compared to UP. ICG turns out to be a straightforward and useful method to evaluate these hemodynamic features.

OS105. Increased left ventricular mass index in normotensive formerly preeclamptic women is associated with the later development of chronic hypertension

INTRODUCTION

A history of preeclampsia is associated with a 4-fold increased risk to develop chronic hypertension later in life. Interestingly, preeclampsia and chronic hypertension share the presence of increased left ventricular mass and increased left atrial diameter. Whether these increases are also present in the preclinical phase of chronic hypertension in women with a history of preeclampsia is still unknown.

OBJECTIVES

To evaluate whether increased left ventricular mass index and/or left atrial widening in normotensive formerly preeclamptic women are associated with the development of chronic hypertension.

METHODS

324 Women with a history of preeclampsia, who were normotensive at the time of a diagnostic work-up 4 months postpartum, were included in this study. The tests employed included cardiac ultrasound and blood pressure measurements. Left ventricular mass was indexed (LVMi) for length in meters(2.7). To follow up on the health state, we send a health checklist to each screened former patient once every two years. The information of the diagnostic work-up and the one of the returned checklists were used for the statistical analysis by Uni- and Multivariate Cox regression analysis.

RESULTS

Women who had developed chronic hypertension during a medium follow-up period of 6 years showed a significant Hazard Ratio (HR) of 1.11 (95% CI 1.03-1.18) for Left ventricular mass index, 1.13 (95% CI 1.06-1.20) for diastolic BP, 1.07 (95% CI 1.02-1.11) for systolic BP, 1.05 (95% CI 1.01-1.10) for Heart Rate and 0.215 (95% CI 0.055-0.848) for EA ratio. The multivariate top-down analysis showed a significant HR only for LVMi and diastolic BP, 1.08 (95% CI 1.00-1.18) and 1.10 (95% CI 1.02-1.19), respectively.

CONCLUSION

Increased diastolic blood pressure and increased LVMi in normotensive formerly preeclamptic women are both associated with the development of chronic hypertension.

PP018 Cardiac reflex responses measured by impedance cardiography are different between low and high cardiac output pre-eclampsia

INTRODUCTION

Pre-eclampsia (PE) has been categorised into subtypes depending on low or high cardiac output (CO) states. Are cardiac reflex responses (CRR) different between these two subtypes?

OBJECTIVES

Impedance cardiography (ICG) measurements of cardiac cycle time intervals (CCTI) before and after orthostatic challenge are evaluated in the clinical phase of PE with low and high CO (LPE and HPE, respectively).

METHODS

Examinations were performed in 25 LPE (CO⩽7l/min) and 16 HPE (CO⩾9l/min). A third generation ICG device using a four electrode arrangement (NICCOMO, Medis, Germany) was used to measure CCTI in supine position and after moving to upright position. The pre-ejection period (PEP) is the time-interval between ventricular depolarisation and start of aortic flow. The left ventricular ejection time (LVET) is the time-interval between opening and closing of the aortic valve. Systolic time ratio (STR) is PEP/LVET. Diastolic time (DT) is the heart period duration - (PEP+LVET). Time intervals were expressed as a percentage of the heart period duration, i.e. PEPi, LVETi and DTi. Orthostatic-induced changes from supine to upright position (cardiac reflex response or CRR) were evaluated using One-sample Wilcoxon Signed Rank Tests. All CRRs were compared between LPE and HPE using Mann-Whitney U tests. Data are presented as medians (interquartile ranges).

RESULTS

Maternal age was comparable between LPE and HPE [29 (26-34) vs 28 (26-33) years; p=0.55]. This was also true for gestational age [34 (30-38) vs 36 (31-39) weeks; p=0.50], and pre-gestational BMI [24 (22-30) vs 25 (24-32); p=0.21]. Birth weight percentiles were lower in LPE compared to HPE [18 (5-31) vs 44 (18-83); p<0.01]. CRRs within each group are shown in Table 1. CRRs of PEP, PEPi and DT were different between LPE and HPE [p⩽0.04], whereas changes in LVET, LVETi, DTi and STR were not [p⩾0.09]. Reflex-induced changes of diastolic blood pressure and heart rate (HR) were not significantly different between LPE and HPE [p⩾0.41].

CONCLUSION

Orthostasis does not change PEP in HPE, but induces a significant increase of PEP in LPE. PEP is dependent on HR, preload, afterload and sympathetic activity. There is no difference in the reflex-induced response of HR, DBP (∼afterload), and STR (∼sympathetic activity) between the two groups. This suggests that the orthostatic-induced change in the isovolumetric contraction time in LPE is preload-induced. Our observations suggest that hemodynamic background mechanisms behind LPE and HPE are different, and support the view that these subtypes are two different clinical entities.

Role of dysfunctional maternal venous hemodynamics in the pathophysiology of pre-eclampsia: a review

The venous compartment has an important function in regulation and control of cardiac output. Abnormalities of cardiac output have been found in early gestational stages of both early- and late-onset pre-eclampsia. The venous compartment also maintains the balance between circulating and non-circulating blood volumes and regulates the amount of reserve blood stored in the splanchnic venous bed. It is well known that adaptive regulation of maternal blood volume is disturbed in pre-eclampsia. Abnormal venous hemodynamics and venous congestion are responsible for secondary dysfunction of several organs, such as the kidneys in cardiorenal syndrome and the liver in cardiac cirrhosis. Renal and liver dysfunctions are among the most relevant clinical features of pre-eclampsia. Doppler sonography studies have shown that the maternal venous compartment is subject to gestational adaptation, and that blood flow characteristics at the level of renal interlobar and hepatic veins are different in pre-eclampsia compared with uncomplicated pregnancy. In comparison to late-onset pre-eclampsia, in early-onset pre-eclampsia venous Doppler flow abnormalities are more prominent and present up to weeks before clinical symptoms. This paper reviews the growing evidence that dysfunction of maternal venous hemodynamics is part of the pathophysiology of pre-eclampsia and may perhaps be more important than is currently considered. Doppler sonography is a safe and easily performed method with which to study maternal venous hemodynamics. Therefore, exploring the role of maternal venous hemodynamics using Doppler sonography is an exciting new research topic for those who are interested in cardiovascular background mechanisms, as well as prediction and clinical work-up of pre-eclampsia.

Maternal renal interlobar vein impedance index is higher in early- than in late-onset pre-eclampsia

OBJECTIVES

To test the hypothesis that Doppler characteristics of maternal renal interlobar veins (RIV) are different between pregnancies affected by early-onset pre-eclampsia (EP) and those affected by late-onset pre-eclampsia (LP).

METHODS

A gestational age of 34 weeks was considered to differentiate EP from LP. All women had a renal duplex scan according to a standard protocol, with known intraobserver correlation coefficient (0.88). Maximum (Vmax) and minimum (Vmin) RIV velocities were measured on two occasions (between 28 and 32 and between 34 and 37 weeks) in 18 women with uncomplicated pregnancy (UP). In women with EP (n = 32) or LP (n = 41), these variables were measured once, within 3 days following hospital admission. Delta velocity (DeltaV) was calculated as Vmax - Vmin and the RIV impedance index (RIVI) was calculated as DeltaV/Vmax. Data on neonatal outcome and maternal renal function were obtained for UP and those with EP and LP, and group-specific means +/- SD were calculated and compared.

RESULTS

Compared with UP, the RIVI of both left and right kidneys was higher in those with EP (0.49 +/- 0.13 vs. 0.36 +/- 0.04, P = 0.0001, and 0.46 +/- 0.15 vs. 0.33 +/- 0.04, P = 0.0008) and in those with LP (0.41 +/- 0.07 vs. 0.37 +/- 0.06, P = 0.04, and 0.38 +/- 0.12 vs. 0.30 +/- 0.05, P = 0.009). RIVI was higher in pregnancies with EP than in those with LP (P < or = 0.01), and this difference was associated with lower median birth-weight percentiles (22.5 (interquartile range (IQR), 15-35) vs. 40.0 (IQR, 12-55), P = 0.01), higher maternal serum uric acid concentrations (419 +/- 84 vs. 374 +/- 85 micromol/L, P = 0.03) and higher proteinuria (4131 +/- 3885 vs. 1190 +/- 1133 mg/24 h, P < 0.0001).

CONCLUSION

Maternal vascular maladaption in pre-eclampsia is associated with abnormal Doppler findings in the venous compartment. RIVI is higher in EP than in LP pregnancies and this is associated with lower birth-weight percentiles and higher proteinuria.

Post-pegylated lipoplexes are promising vehicles for gene delivery in RPE cells

The retinal pigment epithelium (RPE) is a potential tissue for gene therapy. We recently demonstrated that pegylation of lipoplexes prevents their aggregation in the vitreous of the eye. However, pegylation of lipoplexes may affect their gene transfer capacity. Therefore we studied the effect of pegylation of lipoplexes on the transfection of RPE cells. "Pre-pegylated" lipoplexes were prepared by mixing pDNA with pegylated liposomes, while "post-pegylated" lipoplexes were obtained by pegylation of (non-pegylated) cationic liposome/DNA complexes with PEG-ceramides. Pre-pegylation of lipoplexes severely inhibited their transfection efficacy. The poor transfection was attributed to an inefficient and slower internalization of pre-pegylated lipoplexes by RPE cells, compared to non-pegylated lipoplexes. In addition, pre-pegylated lipoplexes also remained entrapped in the endosomes of the RPE cells. In contrast, post-pegylation of the lipoplexes with PEG-ceramides strongly improved their transfection efficiency. As PEG-ceramides are believed to leave the lipoplexes upon contact with the cell membranes, this "de-pegylation" results in non-pegylated lipoplexes which successfully escape from the endosomes. In conclusion, post-pegylation of lipoplexes with PEG-ceramides appears to be an attractive strategy to deliver therapeutic DNA to RPE cells as (a) it prevents the lipoplexes from aggregation in vitreous and (b) de-pegylation upon contact with RPE membranes results in successful DNA delivery.

Challenges in non-viral ocular gene transfer

Nowadays, there is no effective treatment for many retinal disorders. Knowledge of the genetic basis of many severe ocular diseases may allow for alternative treatments by gene therapy. Non-viral gene complexes, such as lipo- and poly-plexes, can be delivered to the posterior segment, most often the target tissue, by intravitreal or subretinal injection. Since subretinal injections are very invasive, intravitreal injection is a promising alternative route to deliver gene complexes into the eye. However, the drawback of this technique is the relative long distance the complexes have to travel through the vitreous gel before they reach the retina. This mini-review reports on how non-viral gene complexes behave in vitreous. It especially focuses on how the coating of lipoplexes with poly(ethylene glycol) influences their behaviour in vitreous and the transfection of retinal pigment epithelium.

[Acute psychiatric symptomatology in Wegener's granulomatosis]

A 69-year-old man presented with a manic episode but in fact was found to be suffering from Wegener's granulomatosis, a systemic disease that can attack the central nervous system. This case study demonstrates that in rare cases acute psychiatric symptoms can develop in a patient suffering from Wegener's granulomatosis, that need to be treated in the proper way. The purpose of the discussion is twofold: to draw attention to the rarity of the case and to stress the need for a multidisciplinary approach to systematic diseases.

Critical use of methyl bromide for soil disinfestation in Belgium during 2005

During 2005, Belgium enforced a strict procedure for the assignment of critical-use permits for methyl bromide (MeBr) as a soil disinfestant. This procedure involved an inspection of the site before disinfestation by a representative of a registered institute, and a mandatory demonstration of the presence of a pest or disease for which a critical use permit could be granted according to the Critical Use Nominations (CUNs). The procedure was subject to random inspections by an independent institute. The results of these inspections demonstrated proper and timely evaluation of the permit requests. A total of 113 requests for a MeBr disinfestation permit were submitted in 2005. Out of these, 105 referred to applications in 2005. The remaining 8 requests referred to applications in 2006 and were denied a permit based on the lack of MeBr quotum granted to Belgium for 2006. Of the 105 requests for applications in 2005, 93 received a MeBr application permit for soil disinfestation. These 93 permits represented 15911 kg or 37.3% of the total quotum assigned to Belgium in 2005 (42676 kg). Most of the quotum was used for butterhead lettuce (11456 kg or 72% of the applied MeBr). For most commodities, a surplus in quotum was available. However, for chrysanthemum, the amount requested for critical use exceeded the available quotum. The most important pests and diseases for which a permit was assigned were Meloidogyne, Sclerotinia, Rhizoctonia, Olpidium, Pythium, Pyrenochaeta, Verticillium, and a combination of these fungi and nematodes. The 12 requests for which no permit was granted represented 2010 kg or 11.3% of the total amount requested. In addition, institutes carrying out the assignment procedure reported at least 62 extra cases where they had been contacted by a grower but where no official permit request was filed based on the first inspection. When including those cases, the total reduction of the potentially used amount of MeBr is about 44 %. When adding an estimated 10 to 15% reduction due to the use of alternatives by growers who did not start the permit assignment procedure, the total reduction is approximately 50-55%.

Tertiary syphilis presenting as hepatic bull's eye lesions

We report a rare case of tertiary syphilis (hepatic gummata, asymptomatic neurosyphilis and iridocyclitis) in a 47 year old female patient. Our patient suffered from a troubled sight, pain in the right hypochondrium, one enlarged submandibular lymph node, an elevated sedimentation rate, disturbed liver tests and two hepatic lesions upon abdominal computed tomography. The diagnosis was based upon a liver biopsy and a positive Treponema Pallidum haemagglutination test. The patient was treated with doxycyclin. After treatment the sedimentation rate and liver tests normalised and the hepatic lesions disappeared leaving a small 'scar' on CT-scan; at the end she still complained of a decreased sight. We conclude that syphilitic gummata of the liver have a favourable prognosis when the diagnosis is made early. One has to differentiate with hepatic abscesses, primary tumours and metastases.

Preeclampsia and maladaptation to pregnancy: a role for atrial natriuretic peptide?

BACKGROUND

The majority of women with a history of preeclampsia have either an underlying thrombophilic disorder or a vascular disorder. In this study, we tested the hypothesis that only the latter condition predisposes for abnormal hemodynamic adaptation to pregnancy.

METHODS

Thirty-seven formerly preeclamptic subjects were subdivided into a hypertensive (HYPERT, N = 10), a normotensive thrombophilic (THROMB, N = 13) and a normotensive nonthrombophilic subgroup (NONTHROMB, N = 14). In these women and in 10 normal parous controls, the following variables were measured at least five-months postpartum at day 5 (+/-2) of the menstrual cycle and again at five- and seven-weeks amenorrhea in the next pregnancy: mean arterial pressure, heart rate, cardiac output, central cardiovascular dimensions, plasma volume, glomerular filtration rate, effective renal plasma flow, 17-beta estradiol, progesterone, the hormones of the renin-angiotensin-aldosterone (RAAS) axis, catecholamines and alpha-atrial natriuretic peptide.

RESULTS

The early pregnancy rise in cardiac output, renal variables, RAAS activity, and plasma volume was comparable in all groups. However, the HYPERT and NONTHROMB subgroups differed from controls by a lower plasma volume in the prepregnant state. In addition, only the women in these two subgroups responded to pregnancy by a rise in circulating alpha-atrial natriuretic peptide. In addition, at seven weeks, in the subjects belonging to the HYPERT and NONTHROMB subgroups, plasma volume was the lowest and correlated inversely with the concomitant circulating level of alpha-atrial natriuretic peptide.

CONCLUSION

The hemodynamic adaptation to pregnancy in the HYPERT and NONTHROMB subgroups differs from that in THROMB and controls by an early pregnancy rise in alpha-atrial natriuretic peptide. As a consequence, the early pregnancy plasma volume expansion in the NONTHROMB and HYPERT subgroups is less than in normal parous controls.

Antimicrobial susceptibility of nontyphoidal Salmonella isolated from humans in Belgium

Human nontyphoidal Salmonella infections are the primary cause of foodborne disease in developed countries, resulting in considerable morbidity and occasionally death, especially in immunocompromised patients. Strains of Salmonella that are resistant to antimicrobial agents have become a world-wide health problem. Fluoroquinolones are drugs of choice for treatment of human invasive salmonellosis, and have been useful for the treatment of infections caused by multi-resistant strains. However, strains resistant to ciprofloxacin have been noted. A random sample of 378 Salmonella strains of human origin was collected during 1998. Their susceptibility to 11 antimicrobial agents was determined by the agar dilution method according to NCCLS standards. In total, 38 serotypes were represented of which S. Enteritidis (20.4%), S. Typhimurium (20.4%), S. Hadar (9.0%), S. Brandenburg (7.9%), S. Infantis (7.7%), and S. Virchow (5.3%) were the most common. All strains were susceptible to ceftriaxone and ciprofloxacin. For nalidixic acid the rate of resistance was 19.0%. Of the 72 strains resistant to nalidixic acid, 31 were S. Hadar, and thus 91.2% (31/34) of the S. Hadar isolates showed resistance to nalidixic acid. Most of the S. Hadar strains were also resistant to ampicillin, tetracycline and sulphamethoxazole, and an elevated MIC50 (0.25 microgram/ml) and MIC90 (1 microgram/ml) was observed for ciprofloxacin. The high rate of resistance to nalidixic acid can be a first step towards the development of resistance to ciprofloxacin.

Stereoselective de-ethylation of chloroquine in rat liver microsomes

A qualitative kinetic study on the stereoselective hepatic metabolism of chloroquine was undertaken by separately incubating chloroquine enantiomers with rat liver microsomes. The dependency of desethylchloroquine formation on NADPH suggests a cytochrome P-450 isozyme catalysed metabolism. Over a wide concentration range (1-300 microM), chloroquine metabolism appeared not to follow simple Michaelis-Menten kinetics. The enantiomeric ratio (R/S) of desethylchloroquine was dependent on concentration, and ranged from 8 at 1 microM to 1 at 300 microM. Mutual enantiomer--enantiomer interaction studies at low concentration (1-5 microM) revealed that the formation of (R)-desethylchloroquine was strongly inhibited by (S)-chloroquine. The findings of the present study support the hypothesis that a high-affinity/low capacity enzyme is capable of stereoselective discrimination. At this point, it remains to be proven whether stereoselective metabolism and enantiomer-enantiomer interactions affect the in vivo disposition of chloroquine.

Lubeluzole, a novel long-term neuroprotectant, inhibits the glutamate-activated nitric oxide synthase pathway

The novel drug lubeluzole, but not its (-)-R-isomer, protects against sensorimotor deficits provoked by photochemical stroke in rats. We studied the mechanism of protection of lubeluzole against glutamate toxicity in primary hippocampal cell cultures. In a model for glutamate antagonism, i.e., treatment of the cultures with compound during the glutamate trigger, lubeluzole was not protective. In contrast, after prolonged pretreatment, i.e., administration of compound to the culture for 7 days before glutamate, lubeluzole was neuroprotective. It had an IC50 of 48 nM and its R-isomer was nine times less active. Under these conditions, lubeluzole inhibited glutamate-stimulated guanosine 3',5'-cyclic monophosphate production (IC50 37 nM). Again the R-isomer was seven times less active. The compounds did not affect nitric oxide synthase activity, guanylate cyclase activity or arginine uptake. After prolonged pretreatment, lubeluzole attenuated citrulline production in the culture, which could not be compensated for by excess arginine. Because prolonged lubeluzole treatment does not inhibit glutamate-activated [Ca+2]i rise in these cultures, the findings may indicate that expression of nitric oxide synthase or levels of its cofactors were reduced. Treatment of C6 glioma cells with lubeluzole did not affect lipopolysaccharide/gamma interferon induced guanosine 3',5'-cyclic monophosphate levels, suggesting that lubeluzole does not inhibit the glial nitric oxide synthase pathway. In conclusion, the long-term neuroprotective property of lubeluzole against glutamate toxicity in hippocampal cultures is reflected by the fact of interference with the glutamateactivated nitric oxide synthase pathway. Prolonged treatment may reduce expression of nitric oxide synthase or levels of its cofactors.

Surgical treatment of benign tumours of the salivary glands

In this multicentre retrospective study 30 patients with benign salivary gland tumours are reviewed. Initial operation consisted of total parotidectomy in 6 patients, superficial lobectomy in 13 and tumour enucleation in 11. There were 5 recurrences, treated by enucleation in 1, superficial lobectomy in 2 and extensive total resection in 2 patients. In 18 cases a typical facial nerve dissection was performed. The resected specimens showed a pleiomorph adenoma in 24 cases and monomorph adenoma's in 6 cases. Complications were haematoma formation, Frey syndrome and facial nerve paresis. Recurrences were related to incomplete resection or fragmentation during operation. In this study benign tumours of the salivary glands proved to have a good prognosis, provided a total tumour excision with nerve dissection is performed; the excision should consist of a superficial lobectomy or total parotidectomy depending on the location of the tumour in the lateral or medial part of the gland.

Neuroprotective sigma ligands interfere with the glutamate-activated NOS pathway in hippocampal cell culture

We studied neuroprotective properties of 12 structurally different sigma site ligands in primary rat hippocampal cell cultures and analyzed whether they interfere with glutamate-induced activation of the nitric oxide synthase (NOS) pathway. Neurotoxicity was triggered with 1 mM glutamate on day 8 of culture. Cells were treated with various concentrations of the compounds for 7 days before glutamate exposure (prolonged pretreatment), or during glutamate exposure (acute treatment). Protection was seen after prolonged pretreatment (long-term protection) with sabeluzole, opipramole, haloperidol, ifenprodil, fenpropimorph, carbetapentane, and tiospirone, with pIC50s of 7.30, 7.15, 6.87, 6.68, 6.66, 6.39, and 6.34, respectively. There was no protection with PD 128298, 1,3-ortho-di-tolylguanidine, BMY-14802, (+)3-(3-hydroxyphenyl)-N-1(propyl) piperidine, or dextromethorphan. Upon acute treatment, only ifenprodil was protective. Interference of the drugs with glutamate activation of the NOS pathway was determined by measuring glutamate-activated cGMP formation and citrulline levels. Glutamate-activated cGMP formation was reduced by all neuroprotective sigma ligands after prolonged pretreatment but not after acute treatment. Sigma ligands added to cell culture lysate did not reduce citrulline formation, evidence that there was no direct effect on the NOS enzyme. We conclude that some but not all sigma ligands exert long-term protective properties against glutamate-induced neurotoxicity in primary hippocampal cultures, and that this protection is accompanied by attenuation of cGMP formation in the NOS pathway. However, inhibition of cGMP formation by itself appeared not sufficient for obtaining neuroprotective effects, as inhibition of glutamate-activated cGMP formation by N omega-nitro-L-arginine, haemoglobin, or PD128298 did not provide neuroprotection.

Bisoprolol and atenolol in essential hypertension: effects on systemic and renal hemodynamics and on ambulatory blood pressure

The acute and short-term responses to bisoprolol and to atenolol on systemic and renal hemodynamics and on ambulatory blood pressure (BP) were compared in a randomized double-blind cross-over study including 14 patients with mild to moderate essential hypertension. After a 4-week placebo period, the patients received either bisoprolol (10 mg once daily, o.d.) or atenolol (100 mg o.d.) for 4 weeks and were switched to the other drug after a new 4-week placebo period. Cardiac output (CO) was measured by Doppler echography, and renal blood flow (RBF) and glomerular filtration rate (GFR) were measured by constant infusion techniques using [123I]iodohippurate and [51Cr]EDTA, respectively. Bisoprolol and atenolol decreased diurnal and nocturnal blood pressure (BP). Both drugs decreased heart rate (HR) and BP both acutely and after 4 weeks. During short-term treatment, CO was maintained with bisoprolol but reduced by atenolol (by 17%). RBF decreased after the first drug intake (by 9 and 12%, respectively) but returned to its baseline value after 4 weeks, so that calculated renal vascular resistance (RVR) was reduced (by 12 and 15%, respectively). Overall, GFR was not affected by treatment. Bisoprolol and atenolol are effective antihypertensive agents that preserve renal hemodynamics during short-term treatment.

[Prosthetic duplication of the ascending aorta]

A simple implantation technique for multiple bypass of the ascending aorta with cervico-encephalic and infradiaphragmatic targets is reported. A conduit made by termino-terminal suture of two bifurcated grafts is anastomosed latero-laterally to the ascending aorta. The procedure is easy to perform and provides a suitable trajectory to the grafts.