Trends and Variation in the Use of Radiotherapy in Non-metastatic Rectal Cancer: a 14-year Nationwide Overview from the Netherlands

AIMS

This study describes nationwide primary radiotherapy utilisation trends for non-metastasised rectal cancer in the Netherlands between 2008 and 2021. In 2014, both colorectal cancer screening and a new guideline specifying prognostic risk groups for neoadjuvant treatment were implemented.

MATERIALS AND METHODS

Patients with non-metastasised rectal cancer in 2008-2021 (n = 37 510) were selected from the Netherlands Cancer Registry and classified into prognostic risk groups. Treatment was studied over time and age. Multilevel logistic regression analyses were carried out to identify factors associated with (i) radiotherapy versus chemoradiotherapy use for intermediate rectal cancer and (ii) chemoradiotherapy without versus with surgery for locally advanced rectal cancer.

RESULTS

For early rectal cancer, the use of neoadjuvant radiotherapy decreased (15% to 5% between 2008 and 2021), whereas the use of endoscopic resections increased (8% in 2015, 17% in 2021). In intermediate-risk rectal cancer, neoadjuvant chemoradiotherapy (43% until 2011, 25% in 2015) shifted to radiotherapy (42% in 2008, 50% in 2015), the latter being most often applied in older patients. In locally advanced rectal cancer, the use of chemoradiotherapy without surgery increased (2-4% in 2008-2013, 17% in 2019-2021). Both neoadjuvant treatment in intermediate disease and omission of surgery following chemoradiotherapy in locally advanced disease varied with increasing age (odds ratio>75vs<50: 2.17, 95% confidence interval 1.54-3.06) and treatment region (Southwest and Northwest odds ratio 0.63, 95% confidence interval 0.42-0.93 and odds ratio 0.65, 95% confidence interval 0.44-0.95, respectively, compared with the North).

CONCLUSION

Treatment patterns in non-metastasised rectal cancer significantly changed over time. Effects of both the national screening programme and the new treatment guideline were apparent, as well as a paradigm shift towards organ preservation (watch-and-wait). Observed regional variations may indicate adoption differences regarding new treatment strategies.

Nonlinear effects at the electrode-tissue interface of deep brain stimulation electrodes

Objective.The electrode-tissue interface provides the critical path for charge transfer in neurostimulation therapies and exhibits well-established nonlinear properties at high applied currents or voltages. These nonlinear properties may influence the efficacy and safety of applied stimulation but are typically neglected in computational models. In this study, nonlinear behavior of the electrode-tissue interface impedance was incorporated in a computational model of deep brain stimulation (DBS) to simulate the impact on neural activation and safety considerations.Approach.Nonlinear electrode-tissue interface properties were incorporated in a finite element model of DBS electrodesin vitroandin vivo,in the rat subthalamic nucleus, using an iterative approach. The transition point from linear to nonlinear behavior was determined for voltage and current-controlled stimulation. Predicted levels of neural activation during DBS were examined and the region of linear operation of the electrode was compared with the Shannon safety limit.Main results.A clear transition of the electrode-tissue interface impedance to nonlinear behavior was observed for both current and voltage-controlled stimulation. The transition occurred at lower values of activation overpotential for simulatedin vivothanin vitroconditions (91 mV and 165 mV respectively for current-controlled stimulation; 110 mV and 275 mV for voltage-controlled stimulation), corresponding to an applied current of 30μA and 45μA, or voltage of 330 mV at 1 kHz. The onset of nonlinearity occurred at lower values of the overpotential as frequency was increased. Incorporation of nonlinear properties resulted in activation of a higher proportion of neurons under voltage-controlled stimulation. Under current-controlled stimulation, the predicted transition to nonlinear behavior and Faradaic charge transfer at stimulation amplitudes of 30μA, corresponds to a charge density of 2.29μC cm-2and charge of 1.8 nC, well-below the Shannon safety limit.Significance.The results indicate that DBS electrodes may operate within the nonlinear region at clinically relevant stimulation amplitudes. This affects the extent of neural activation under voltage-controlled stimulation and the transition to Faradaic charge transfer for both voltage- and current-controlled stimulation with important implications for targeting of neural populations and the design of safe stimulation protocols.

Stimulation-induced changes at the electrode-tissue interface and their influence on deep brain stimulation

OBJECTIVE

During deep brain stimulation (DBS) the electrode-tissue interface forms a critical path between device and brain tissue. Although changes in the electrical double layer and glial scar can impact stimulation efficacy, the effects of chronic DBS on the electrode-tissue interface have not yet been established.

APPROACH

In this study, we characterised the electrode-tissue interface surrounding chronically implanted DBS electrodes in rats and compared the impedance and histological properties at the electrode interface in animals that received daily stimulation and in those where no stimulation was applied, up to eight weeks post-surgery. A computational model was developed based on the experimental data, which allowed the dispersive electrical properties of the surrounding encapsulation tissue to be estimated. The model was then used to study the effect of stimulation-induced changes in the electrode-tissue interface on the electric field and neural activation during voltage- and current-controlled stimulation.

MAIN RESULTS

Incorporating the observed changes in simulations in silico, we estimated the frequency-dependent dielectric properties of the electrical double layer and surrounding encapsulation tissue. Through simulations we show how stimulation-induced changes in the properties of the electrode-tissue interface influence the electric field and alter neural activation during voltage-controlled stimulation. A substantial increase in the number of stimulated collaterals, and their distance from the electrode, was observed during voltage-controlled stimulation with stimulated ETI properties. In vitro examination of stimulated electrodes confirmed that high frequency stimulation leads to desorption of proteins at the electrode interface, with a concomitant reduction in impedance.

SIGNIFICANCE

The demonstration of stimulation-induced changes in the electrode-tissue interface has important implications for future DBS systems including closed-loop systems where the applied stimulation may change over time. Understanding these changes is particularly important for systems incorporating simultaneous stimulation and sensing, which interact dynamically with brain networks.

Nationwide Screening for Bee Viruses and Parasites in Belgian Honey Bees

The health of honey bees is threatened by multiple factors, including viruses and parasites. We screened 557 honey bee (Apis mellifera) colonies from 155 beekeepers distributed all over Belgium to determine the prevalence of seven widespread viruses and two parasites (Varroa sp. and Nosema sp.). Deformed wing virus B (DWV-B), black queen cell virus (BQCV), and sacbrood virus (SBV) were highly prevalent and detected by real-time RT-PCR in more than 95% of the colonies. Acute bee paralysis virus (ABPV), chronic bee paralysis virus (CBPV) and deformed wing virus A (DWV-A) were prevalent to a lower extent (between 18 and 29%). Most viruses were only present at low or moderate viral loads. Nevertheless, about 50% of the colonies harbored at least one virus at high viral load (>10⁷ genome copies/bee). Varroa mites and Nosema sp. were found in 81.5% and 59.7% of the honey bee colonies, respectively, and all Nosema were identified as Nosema ceranae by real time PCR. Interestingly, we found a significant correlation between the number of Varroa mites and DWV-B viral load. To determine the combined effect of these and other factors on honey bee health in Belgium, a follow up of colonies over multiple years is necessary.

Routine Analysis of Proteins by Kjeldahl and Dumas Methods: Review and Interlaboratory Study Using Dairy Products

The Kjeldahl and Dumas (combustion) methods were compared in 11 laboratories analyzing samples of milk, skim milk powder, whole milk powder, whey protein concentrate, infant formula, casein, caseinate, 2 reference compounds (glycine and EDTA), and a secondary reference skim milk powder. The comparison was conducted by using international standards where applicable. Overall means were 8.818 g N/100 g by the Kjeldahl method and 8.810 g N/100 g by the Dumas method. No evidence was found for a consistent bias between methods that may be of concern in the trading of dairy produce. A review of more than 10 related trials revealed a lack of consensus in the bias between the 2 methods, suggesting that differences in methodology and sources of systematic error may be contributors. For samples containing &gt;2 g N/100 g, the Dumas relative repeatability and reproducibility standard deviations were consistently about 0.35 and 0.75%, respectively, whereas the corresponding Kjeldahl values declined generally with N content and were significantly larger. The Dumas precision characteristics may be due to the dominance of Leco analyzers in this trials, and in most other recent trials, rather than an inherent method attribute. Protein determination methods for dairy products need to be reviewed and updated. The Dumas method needs Codex Alimentarius status as a recognized test method.

[Outcome after surgical treatment of calcaneal fractures]

BACKGROUND

After controversial discussions in the literature about therapy regimens for calcaneal fractures, a retrospective study of patients operatively treated in a maximum care trauma center was conducted.

OBJECTIVE

Investigation of the influencing factors on the treatment quality of operatively treated patients with calcaneal fractures.

MATERIAL AND METHODS

Between 2005 and 2013 a total of 90 patients with calcaneal fractures were surgically treated in this hospital with locking plate osteosynthesis. A total of 48 patients with 55 fractures were retrospectively investigated. The assessment with respect to posttraumatic arthrosis was made radiologically and Böhler's and Gissane's angles were also determined. Clinically AOFAS and SF-36 scores were documented. The results were statistically tested with respect to possible risk factors.

RESULTS

A total of 9 patients (18.8%) were found with complications necessitating operative revision, with 8 patients requiring subtalar arthrodesis and 1 patient with a deep wound infection. Nicotine abuse and a long interval between trauma and reconstructive surgery were identified as factors that influenced the development of wound healing problems. The average AOFAS score was 68 points and the SF-36 was 58.86 points. A poor result in the scores was caused by the development of symptomatic arthritis and the type of insurance. In this cohort factors, such as age and complexity of fractures were not correlated with a poor result.

CONCLUSION

In this patient collective nicotine abuse and a long interval between trauma and surgery were risk factors for development of wound infections. Other factors with an influence on the outcome were the postoperative development of arthritis and the type of health insurance; however, patient age had no impact on the outcome.

The role of a small posterior malleolar fragment in trimalleolar fractures

Aims

The aim of this study was to investigate the effect of a posterior malleolar fragment (PMF), with < 25% ankle joint surface, on pressure distribution and joint-stability. There is still little scientific evidence available to advise on the size of PMF, which is essential to provide treatment. To date, studies show inconsistent results and recommendations for surgical treatment date from 1940.

Materials and Methods

A total of 12 cadaveric ankles were assigned to two study groups. A trimalleolar fracture was created, followed by open reduction and internal fixation. PMF was fixed in Group I, but not in Group II. Intra-articular pressure was measured and cyclic loading was performed.

Results

Contact area decreased following each fracture, while anatomical fixation restored it nearly to its intact level. Contact pressure decreased significantly with fixation of the PMF. In plantarflexion, the centre of force shifted significantly posteriorly in Group II and anteriorly in Group I. Load to failure testing showed no difference between the groups.

Conclusion

Surgical reduction of a small PMF with less than 25% ankle joint surface improves pressure distribution but does not affect ankle joint stability. Cite this article: Bone Joint J 2018;100-B:95–100.

Altered defaecatory behaviour and faecal incontinence in a video-tracked animal model of pudendal neuropathy

AIM

The aim was to develop a behavioural animal model of faecal continence and assess the effect of retro-uterine balloon inflation (RBI) injury. RBI in the rat causes pudendal neuropathy, a risk factor for obstetric related faecal incontinence in humans.

METHOD

Video-tracking of healthy rats (n = 12) in a cage containing a latrine box was used to monitor their defaecatory behaviour index (DBI) over 2 weeks. The DBI (range 0-1) was devised by dividing the defaecation rate (pellets per hour) outside the latrine by that of the whole cage. A score of 0 indicates all pellets were deposited in the latrine. Subsequently, the effects of RBI (n = 19), sham surgery (n = 4) and colostomy (n = 2) were determined by monitoring the DBI for 2 weeks preoperatively and 3 weeks postoperatively.

RESULTS

The DBI for healthy rats was 0.1 ± 0.03 with no significant change over 2 weeks (P = 0.71). In the RBI group, 13 of 19 rats (68%) showed no significant change in DBI postoperatively (0.08 ±  -0.05 vs 0.11 ±  -0.07) while in six rats the DBI increased from 0.16 ±  -0.09 to 0.46 ± 0.23. The negative control, sham surgery, did not significantly affect the DBI (0.09 ± 0.06 vs 0.08 ± 0.04, P = 0.14). The positive control, colostomy, increased the DBI from 0.26 ± 0.03 to 0.86 ± 0.08.

CONCLUSIONS

This is the first study showing a quantifiable change in defaecatory behaviour following injury in an animal model. This model of pudendal neuropathy affects continence in 32% of rats and provides a basis for research on interventions for incontinence.

Reversal of sensory deficit through sacral neuromodulation in an animal model of fecal incontinence

BACKGROUND

Sacral neuromodulation (SNM) is a treatment option for intractable fecal incontinence. The mechanism of action is unclear, however, increasing evidence for afferent somatosensory effects exists. This study's aim was to elucidate effects of acute SNM on the cerebral cortex in a rodent model of pudendal nerve injury.

METHODS

The effects of 14 Hz and 2 Hz SNM on sensory cortical activation were studied. In 32 anesthetized rats, anal canal evoked potentials (EPs) were recorded over the primary somatosensory cortex. Pudendal nerve injury was produced by 1-hour inflation of two intra-pelvic balloons. Four groups were studied: balloon injury, balloon injury plus either 14 Hz or 2 Hz SNM, sham operation. Immunohistochemistry for the neural plasticity marker polysialylated neural cell adhesion molecule (PSA-NCAM) positive cells (numerical density and location) in the somatosensory cortex was performed.

KEY RESULTS

Anal EP amplitudes diminished during balloon inflation; 14 Hz SNM restored diminished anal EPs to initial levels and 2 Hz SNM to above initial levels. Evoked potential latencies were prolonged during balloon inflation. The numerical density of PSA-NCAM positive cells increased in the SNM groups, but not in sham or balloon injury without SNM. Stimulated cortices showed clusters of PSA-NCAM positive cells in layers II, IV, and V. Post SNM changes were similar in both SNM groups.

CONCLUSIONS & INFERENCES

Sacral neuromodulation augments anal representation in the sensory cortex and restores afferent pathways following injury. PSA-NCAM positive cell density is increased in stimulated cortices and positive cells are clustered in layers II, IV, and V.

Acute lumbosacral nerve stimulation does not affect anorectal motor function in a rodent model

BACKGROUND

Sacral nerve stimulation has become a first line treatment for fecal incontinence, however, its effect on the motor function of the anorectum is uncertain. The aim of this study was to apply acute lumbosacral nerve stimulation in an animal model and to determine its effect on the external and internal anal sphincter forces, the rectoanal inhibitory and excitatory reflexes, and the slow wave frequency of the internal anal sphincter.

METHODS

Lumbosacral nerve stimulation was applied to 16 nulliparous female rats. A novel in vivo preparation was designed to allow simultaneous monitoring of external and internal anal sphincter forces. The effect of rectal distension on the two anal sphincters was also studied.

KEY RESULTS

Lumbosacral nerve stimulation delivered at either S1 or L6 in rodents did not affect sphincter forces, rectoanal reflexes or slow wave frequency of anal canal smooth muscle.

CONCLUSIONS & INFERENCES

The absence of effect on the motor pathways of continence suggests that the mechanism of action is predominantly on sensory feedback mechanisms from the anorectum, thereby increasing cortical awareness of the pelvic floor.

Interferometric phase detection at x-ray energies via Fano resonance control

Modern x-ray light sources promise access to structure and dynamics of matter in largely unexplored spectral regions. However, the desired information is encoded in the light intensity and phase, whereas detectors register only the intensity. This phase problem is ubiquitous in crystallography and imaging and impedes the exploration of quantum effects at x-ray energies. Here, we demonstrate phase-sensitive measurements characterizing the quantum state of a nuclear two-level system at hard x-ray energies. The nuclei are initially prepared in a superposition state. Subsequently, the relative phase of this superposition is interferometrically reconstructed from the emitted x rays. Our results form a first step towards x-ray quantum state tomography and provide new avenues for structure determination and precision metrology via x-ray Fano interference.

A systematic review of sacral nerve stimulation mechanisms in the treatment of fecal incontinence and constipation

BACKGROUND

Sacral nerve stimulation (SNS) is now well established as a treatment for fecal incontinence (FI) resistant to conservative measures and may also have utility in the management of chronic constipation; however, mechanism of action is not fully understood. End organ effects of SNS have been studied in both clinical and experimental settings, but interpretation is difficult due to the multitude of techniques used and heterogeneity of reported findings. The aim of this study was to systematically review available evidence on the mechanisms of SNS in the treatment of FI and constipation.

METHODS

Two systematic reviews of the literature (performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses framework) were performed to identify manuscripts pertaining to (a) clinical and (b) physiological effects of SNS during the management of hindgut dysfunction.

KEY RESULTS

The clinical literature search revealed 161 articles, of which 53 were deemed suitable for analysis. The experimental literature search revealed 43 articles, of which nine were deemed suitable for analysis. These studies reported results of investigative techniques examining changes in cortical, gastrointestinal, colonic, rectal, and anal function.

CONCLUSIONS & INFERENCES

The initial hypothesis that the mechanism of SNS was primarily peripheral motor neurostimulation is not supported by the majority of recent studies. Due to the large body of evidence demonstrating effects outside of the anorectum, it appears likely that the influence of SNS on anorectal function occurs at a pelvic afferent or central level.

Effects of stimulation frequency and intensity in sacral neuromodulation on anorectal inputs to the somatosensory cortex in an experimental model

Introduction

Although sacral neuromodulation (SNM) is an established treatment for faecal incontinence, stimulation parameters have been derived empirically and only one frequency (14 Hz) is employed clinically. The aim of this study was to test a range of stimulation frequencies to establish an optimal frequency of SNM for maximum augmentation of anal canal cortical evoked potentials (EPs) in an animal model.

Methods

In female Wistar rats, anal canal EPs were recorded over the primary somatosensory cortex using a flexible multielectrode array, and the effect of SNM was studied. SNM was applied at 0·1–100 Hz and a frequency response curve plotted. The data were fitted to a quadratic equation.

Results

The magnitude of potentiation of anal canal EPs caused by SNM depended significantly on stimulation frequency (P &lt; 0·001). The frequency–potentiation relationship was parabolic in form, with a clear optimum at 2 Hz. The SNM must be applied for at least 3 min. The theoretical maximal potentiation predicted by the model was not found to be statistically different to actual data recorded (P = 0·514–0·814). The response depended on stimulation amplitude in an ‘all-or-nothing’ fashion. EPs were augmented when the SNM intensity was 0·5 times the motor threshold to tail twitch or greater, but values below this intensity failed to affect the EPs.

Conclusion

The effect of SNM in this animal model is governed principally by frequency, with an optimum of 2 Hz. If animal data can be translated to humans, optimization of SNM frequency may offer a clinically relevant improvement in the efficacy of SNM.

Full counting statistics of laser excited Rydberg aggregates in a one-dimensional geometry

We experimentally study the full counting statistics of few-body Rydberg aggregates excited from a quasi-one-dimensional atomic gas. We measure asymmetric excitation spectra and increased second and third order statistical moments of the Rydberg number distribution, from which we determine the average aggregate size. Estimating rates for different excitation processes we conclude that the aggregates grow sequentially around an initial grain. Direct comparison with numerical simulations confirms this conclusion and reveals the presence of liquidlike spatial correlations. Our findings demonstrate the importance of dephasing in strongly correlated Rydberg gases and introduce a way to study spatial correlations in interacting many-body quantum systems without imaging.

Directional emission of dielectric disks with a finite scatterer in the THz regime

In the Terahertz (THz) domain, we investigate both numerically and experimentally the directional emission of whispering gallery mode resonators that are perturbed by a small scatterer in the vicinity of the resonators rim. We determine quality factor degradation, the modal structure and the emission direction for various geometries. We find that scatterers do allow for directional emission without destroying the resonator's quality factor. This finding allows for new geometries and outcoupling scenarios for active whispering gallery mode structures such as quantum cascade lasers and passive resonators such as evanescent sensors. The experimental results agree well with finite difference time domain simulations.

Sub-Poissonian statistics of Rydberg-interacting dark-state polaritons

We observe individual dark-state polaritons as they propagate through an ultracold atomic gas involving Rydberg states coupled via an electromagnetically induced transparency resonance. Strong long-range interactions between Rydberg excitations give rise to a blockade between polaritons, resulting in large optical nonlinearities and modified polariton number statistics. By combining optical imaging and high-fidelity detection of the Rydberg polaritons we investigate both aspects of this coupled atom-light system. We map out the full nonlinear optical response as a function of atomic density and follow the temporal evolution of polaritons through the atomic cloud. In the blockade regime, the statistical fluctuations of the polariton number drop well below the quantum noise limit. The low level of fluctuations indicates that photon correlations modified by the strong interactions have a significant backaction on the Rydberg atom statistics.

Is there a nitrergic modulation of the rat external anal sphincter?

Nitric oxide is known to relax the internal anal sphincter, but its effect on the external anal sphincter (EAS) is unknown. The aim of this study was to investigate whether there is a nitrergic nerve plexus that modulates the EAS, similar to that found in oesophageal striated muscle. An in vitro ring preparation of rat anal canal was used to evaluate the effects of the nitric oxide synthase inhibitor N(ω)-nitro-L-arginine (L-NNA) and the NO donor sodium nitroprusside (SNP) on the EAS in conditions of neuromuscular blockade and the effect of SNP on nerve-evoked contractions. Immunohistological experiments were conducted to determine whether the neuronal isoform of nitric oxide synthase (nNOS) is present in the EAS. During direct muscle stimulation neither L-NNA (P = 0.32) nor SNP (P = 0.19) significantly changed the EF(50), which is the frequency at which 50% of maximal contraction is reached, compared with a time-dependent control. Nerve-evoked contractions were also not altered by addition of SNP to the tissue bath. Immunohistohistological experiments clearly showed co-localization of nNOS-positive nerve fibres at motor endplates of the oesophagus but not in the EAS. The internal anal sphincter was richly innervated by nitrergic fibres, but these did not extend into the EAS. In conclusion, there are no nitrergic motor fibres innervating the EAS, neurotransmission at the motor endplates is not affected by NO, and NO does not affect muscle force directly in conditions of neuromuscular blockade. There is, therefore, no evidence that EAS contraction is directly modulated by NO or by pudendal nitrergic fibres or diffusion from neighbouring nitrergic plexuses of the anal canal.

Inhibition of microglial and astrocytic inflammatory responses by the immunosuppressant mycophenolate mofetil

AIMS

Nucleotide depletion induced by the immunosuppressant mycophenolate mofetil (MMF) has been shown to exert neuroprotective effects. It remains unclear whether nucleotide depletion directly counteracts neuronal demise or whether it inhibits microglial or astrocytic activation, thereby resulting in indirect neuroprotection.

METHODS

Effects of MMF on isolated microglial cells, astrocyte/microglial cell co-cultures and isolated hippocampal neurones were analysed by immunocytochemistry, quantitative morphometry, and elisa.

RESULTS

We found that: (i) MMF suppressed lipopolysaccharide-induced microglial secretion of interleukin-1β, tumour necrosis factor-α and nitric oxide; (ii) MMF suppressed lipopolysaccharide-induced astrocytic production of tumour necrosis factor-α but not of nitric oxide; (iii) MMF strongly inhibited proliferation of both microglial cells and astrocytes; (iv) MMF did not protect isolated hippocampal neurones from excitotoxic injury; and (v) effects of MMF on glial cells were reversed after treatment with guanosine.

CONCLUSIONS

Nucleotide depletion induced by MMF inhibits microglial and astrocytic activation. Microglial and astrocytic proliferation is suppressed by MMF-induced inhibition of the salvage pathway enzyme inosine monophosphate dehydrogenase. The previously observed neuroprotection after MMF treatment seems to be indirectly mediated, making this compound an interesting immunosuppressant in the treatment of acute central nervous system lesions.

Phase stability of lithium azide at pressures up to 60 GPa

We studied lithium azide (LiN(3)) by x-ray diffraction and Raman spectroscopy at hydrostatic compression up to pressures above 60 GPa at room temperature. The results of x-ray diffraction analyses reveal the stability of the ambient-pressure C 2/m crystal structure up to the highest pressure. The pressure dependence of librational modes provides evidence for an order-disorder transition at low pressures (below 3 GPa), similar to the transition observed previously at low temperatures. The observed structure stability indicates that this transition is not associated with structural changes. The phase stability of LiN(3) is in contrast to that of sodium azide (which is isostructural at ambient pressure), for which a set of phase transitions has been reported at pressures below 50 GPa.

Validation of preimplantation genetic diagnosis by PCR analysis: genotype comparison of the blastomere and corresponding embryo, implications for clinical practice

The aim of this study was to validate the overall preimplantation genetic diagnosis (PGD)-PCR procedure and to determine the diagnostic value. Genotyped embryos not selected for embryo transfer (ET) and unsuitable for cryopreservation after PGD were used for confirmatory analysis. The PGD genotyped blastomeres and corresponding embryos were compared, and morphology was scored on Day 4 post fertilization. To establish the validity of the PGD-PCR procedure and the diagnostic value, misdiagnosis rate, false-negative rate and negative predictive value were calculated. Moreover, comparison on the validity was made for the biopsy of one or two blastomeres. For the total embryo group (n = 422), a misdiagnosis rate of 7.1% and a false-negative rate of 3.1% were found. The negative predictive value was 96.1%. Poor morphology Day 4 embryos (Class 1) were over-represented in the embryo group in which the blastomere genotype was not confirmed by the whole embryo genotype. The misdiagnosis rate of Class 1 embryos was 12.5% and the false-negative rate 17.1%. Exclusion of these embryos resulted in a misdiagnosis rate of 6.1%, a false-negative rate of 0.5% and a negative predictive value of 99.3%. The two blastomere biopsies revealed a significant higher positive predictive value, lowering the misdiagnosis rate, whereas the negative predictive value remained the same. In conclusion, the PGD-PCR procedure is a valid diagnostic method to select unaffected embryos for ET. The misdiagnosis and false-negative rates decrease by rejecting Class 1 embryos for ET. The biopsy of a second blastomere improves the positive predictive value, lowering the misdiagnosis rate.

Resonant interferometric lithography beyond the diffraction limit

A novel approach for the generation of subwavelength structures in interferometric optical lithography is described. Our scheme relies on the preparation of the system in a position dependent trapping state via phase shifted standing wave patterns. Since this process only comprises resonant atom-field interactions, a multiphoton absorption medium is not required. The contrast of the induced pattern does only depend on the ratios of the applied field strengths such that our method in principle works at very low laser intensities.

Reorganization of synaptic inputs to developing skeletal muscle fibres

During early stages of postnatal development skeletal muscle fibres of mammals are contacted by several axons. The transition from poly- to mononeuronal innervation has been extensively studied on the rat soleus. The role of activity in this process has been acknowledged but the mechanisms leading to synapse remodelling are not understood. The participation of the muscle has to be taken into account; if muscles are paralysed by alpha-bungarotoxin, the elimination of terminals is arrested. Changes in Ca2+ also influence the rate of removal of terminals. Calcium seems to act through a calcium-activated neutral protease (CANP) present in nerve endings. If CANP is inhibited, elimination fails to take place. Thus Ca2+ enters the terminal and activates the CANP. Release of K+ ions from active muscle could link muscle activity and synapse elimination. Excess K+ was found to reduce nerve-muscle contacts, by depolarizing terminals and allowing Ca2+ entry. A greater increase of Ca2+ concentration in smaller terminals would be expected, because of their surface-to-volume ratio, and they are preferentially eliminated. Thus elimination depends on the unequal size of terminals at the endplate. Therefore the 'survivability' of individual nerve endings may already be determined at the time of synapse elimination.

Quantum interference enforced by time-energy complementarity

The interplay of the concepts of complementarity and interference in the time-energy domain are studied. In particular, we theoretically investigate the fluorescence light from a J = 1/2 to J= 1/2 transition that is driven by a monochromatic laser field. We find that the spectrum of resonance fluorescence exhibits a signature of vacuum-mediated interference effects, whereas the total intensity is not affected by interference. We demonstrate that this result is a consequence of the principle of complementarity, applied to time and energy. Since the considered level scheme can be found, e.g., in (198)Hg(+) ions, our model system turns out to be an ideal candidate to provide evidence for as yet experimentally unconfirmed vacuum-induced atomic coherences.

[Clinical course and therapy of Langerhans cell histiocytosis in children and adults]

The Langerhans cell histiocytosis is a rare disease with a clear preference of infancy and an incidence of 0.2 to 1.0/100,000 children occurring worldwide. In 60 to 70% of the cases the first manifestation is before the second year of age. The disease prefers the male sex in a male to female relation of 2:1. Occurrence in adult age is very rare. Up to 10% of the cases are congenital. Both the etiology and the pathogenesis of the disease are unknown. The clinical presentation is extremely variable and covers a wide spectrum from localized involvement with a favorable prognosis to disseminated, malignant and foudroyant course. We report on ten patients, six infants and children and four adolescents and adults. We point out the very variable morphologic manifestations, the different disease course and the therapeutic options.

A retrospective follow-up study on intracytoplasmic sperm injection

PURPOSE

Genetic aspects of male subfertility and the novelty of intracytoplasmic sperm injection (ICSI) as a new technique can influence the development of zygotes and children born after ICSI. Therefore, we evaluated the outcome of ICSI compared to in vitro fertilization (IVF).

METHODS

Data from medical records of 233 total pregnancies and the follow-up of 132 children born after IVF and 120 after ICSI were retrospectively analyzed.

RESULTS

No differences were found between ICSI and IVF for early embryonic development and obstetric outcome. In both groups the rate of women undergoing prenatal chromosomal diagnosis was low, 30.0%. The congenital malformation rate was 3.0% after IVF and 1.7% after ICSI, which was not significantly different. Follow-up on development of children born after IVF and ICSI also showed no significant differences.

CONCLUSIONS

Our results indicate that at this moment ICSI is a safe procedure. However, a consistent prospective follow-up is still mandatory to exclude possible risks.

Elevated serum concentrations of soluble selectin and immunoglobulin type adhesion molecules in patients with inflammatory bowel disease

Adhesion molecules mediate the extravasation of leukocytes and their accumulation in inflamed tissues. In the present study, serum concentrations of the selectin (sP- and sE-selectin) and immunoglobulin supergene family (sICAM-1 and sVCAM-1) of adhesion molecules were measured in 93 patients with inflammatory bowel disease (Crohn's disease, n = 65; ulcerative colitis, n = 28) and 58 age-matched normal controls. sP-selectin serum concentrations (mean +/- SEM ng/ml) of patients with Crohn's disease (399 +/- 33 ng/ml) and ulcerative colitis (385 +/- 42 ng/ml) were increased (P = 0.0067 and P = 0.0193, respectively) compared to controls (251 +/- 33 ng/ml). In contrast, E-selectin serum levels of patients with Crohn's disease (58 +/- 5 ng/ml) and ulcerative colitis (64 +/- 12 ng/ml) were not significantly higher than those of controls (53 +/- 5 ng/ml). sICAM-1 serum concentrations of patients with Crohn's disease (420 +/- 19 ng/ml) and those with ulcerative colitis (375 +/- 40 ng/ml) were elevated (P = 0.0001 and P = 0.0473, respectively) compared to controls (297 +/- 8 ng/ml). Further, sVCAM-1 levels of patients with Crohn's disease (664 +/- 43 ng/ml) and ulcerative colitis (963 +/- 162 ng/ml) were increased (P = 0.0222 and P = 0.0121, respectively) compared to controls (510 +/- 31 ng/ml). With few exceptions, serum levels of soluble adhesion molecules were not significantly correlated to disease activity indices or disease localization. Elevated circulating selectin and immunoglobulin supergene type adhesion molecules may compete with membrane-bound forms for their cognate ligands and thereby limit the rolling and stable adhesion of leukocytes.

Blood-brain barrier water permeability and brain osmolyte content during edema development

OBJECTIVE

To determine mechanisms that limit changes in brain water content during acute edema development.

METHODS

A controlled, laboratory investigation of the physiologic and biochemical correlates of osmotic edema was performed in rats. Hypoosmotic hyponatremia was induced by intraperitoneal injection of distilled water. Serum osmolality and electrolytes and regional blood-brain barrier water permeability. Surface area (P.S) product, osmolyte contents, and capillary size were determined during 120 minutes of hypoosmotic brain edema development. Cerebral water content predicted from these data using a mathematical model of brain water movements was compared with measured changes in brain water content.

RESULTS

Fifteen minutes after distilled water injection, mean +/- SEM blood serum osmolality and sodium concentration decreased from 291 +/- 3 mOsm and 131 +/- 13 mmol/L to 267 +/- 3 mOsm and 102 +/- 9 mmol/L, respectively. Specific gravity of cerebral gray matter, cerebral white matter, and basal ganglia decreased throughout the hypoosmotic exposure period and, for gray and white matter, correlated with blood serum osmolality and sodium plus potassium content. Glutamate, but not glutamine, glycine, or taurine, decreased 120 minutes after water injection. The regional water P.S product decreased by 40% to 60% within 60 minutes of the water injection, while capillary diameters in gray and white matter were unchanged. Brain water movements calculated from the mathematical model correctly predicted actual brain water content only if the hydraulic conductivity of the blood-brain barrier was allowed to vary in proportion to the measured P.S product and the measured loss of brain osmolytes was incorporated into the formulation.

CONCLUSIONS

During the first hours of hypoosmotic hyponatremia, changes in brain volume are limited by increased resistance to osmotic flux of water into the brain and reduction in the brain content of inorganic and, to a smaller degree, organic osmolytes.

Reduced serum levels of a soluble form of the human adhesion receptor CD58 (LFA-3) in patients with inflammatory bowel disease

The activation of monocytes, neutrophils, and B cells by T-lymphocytes appears to play a pivotal role in the pathophysiology of inflammatory bowel disease. The pan T cell marker CD2 and its ligand CD58 mediate these immune function. We asked whether serum levels of a soluble form of CD58 is altered in patients with inflammatory bowel disease. Soluble CD58 was measured in sera from 41 patients with Crohn's disease, 19 patients with ulcerative colitis, and 24 normal controls. Soluble CD58 levels were significantly decreased in sera from patients with ulcerative colitis and even more with Crohn's disease when compared to controls (p = 0.025 and p < 0.0001, respectively). Reduction of soluble CD58 serum levels correlated significantly with various humoral (e.g. erythrocyte sedimentation rate: r = -0.48, p = 0.0002) and clinical parameters of disease activity (e.g. CDAI: r = -0.44, p = 0.005). In conclusion, serum levels of soluble CD58 are reduced in patients with inflammatory bowel disease. Since soluble CD58 can block the CD2/CD58 interaction further studies have to show whether the reduction of soluble CD58 in patients with inflammatory bowel disease contributes to T cell adhesiveness in the mucosa.

Influence of renal function on the steady-state pharmacokinetics of the antiarrhythmic propafenone and its phase I and phase II metabolites

The aim of this study was to investigate the disposition of propafenone and its Phase I and II metabolites in relation to kidney function under steady-state conditions. The mechanism of the renal handling of propafenone glucuronides (filtration, secretion) was also examined. Racemic (R/S) propafenone was administered to 7 young volunteers, to 5 older patients with a normal glomerular filtration rate and to 4 patients with chronic renal failure. No difference was found in the plasma concentrations of propafenone and 5-hydroxypropafenone between the three groups. The propafenone glucuronide (PPFG) concentration was elevated in the older compared to the younger subjects (S-PPFG: 544 vs. 222 nmol.ml-1.mol-1; R-PPFG: 576 vs. 304 nmol.ml-1.mol-1). Although Glomerular filtration rate did not differ, the renal clearance of propafenone glucuronides was reduced in the former group, which could be attributed to their impaired renal secretion. A dramatic increase in propafenone glucuronide concentration was observed in the patients with renal failure (S-PPFG: 2783 nmol.ml-1.mol-1; R-PPFG: 7340 nmol.ml-1.mol-1). In summary, the disposition of propafenone and of its active metabolite 5-hydroxypropafenone was not affected by kidney dysfunction, indicating that no dose adjustment is necessary in patients with renal failure. The accumulation of drug glucuronides in older patients with apparently normal kidney function should be taken into account as a possible factor modifying drug therapy.

Fatal lorcainide poisoning

A case of lorcainide poisoning with fatal outcome is reported. A young girl of 15 ingested, without high lethality of intent, 2500 mg lorcainide, an antiarrhythmic agent. Bradycardia, shock, coma, and cerebral convulsions rapidly occurred. Despite immediate resuscitative measures with high doses of catecholamines and hypertonic sodium bicarbonate the patient died three hours later. The course of lorcainide poisoning was similar to that of other class Ic antiarrhythmic agents.

Unpredictability of flecainide plasma concentrations in patients with renal failure: relationship to side effects and sudden death?

We report a retrospective evaluation of plasma concentrations of flecainide obtained from five dialysis patients during chronic oral treatment. A more than sevenfold variation in the dose/concentration relationship was observed. Plasma concentrations of flecainide above 1,200 ng/ml appeared to be associated with serious side effects and in one case with sudden death. Therefore, flecainide should be used with extreme caution in patients with impaired renal function. Frequent therapeutic drug monitoring should be mandatory.