Extending the viability of human precision-cut intestinal slice model for drug metabolism studies.

Human Precision-cut intestinal slices (hPCIS) are used to study intestinal physiology, pathophysiology, drug efficacy, toxicology, kinetics, and metabolism. However, the use of this ex vivo model is restricted to approximately a 24 h timeframe because of declining viability of the hPCIS during traditional culture. We hypothesized that we could extend the hPCIS viability by using organoid medium. Therefore, we cultured hPCIS for up to 72 h in organoid media [expansion medium (Emed) and differentiation medium (Dmed)]. After incubation, we assessed culture-induced changes on viability markers, specific cell type markers and we assessed the metabolic activity of enterocytes by measuring midazolam metabolite formation. We show that the adenosine triphosphate (ATP)/protein ratio of Emed-cultured hPCIS and morphology of both Emed- and Dmed-cultured hPCIS was improved compared to WME-cultured hPCIS. Emed-cultured hPCIS showed an increased expression of proliferation and stem cell markers, whereas Dmed-cultured hPCIS showed an increased expression of proliferation and enterocyte markers, along with increased midazolam metabolism. Using the Emed, the viability of hPCIS could be extended for up to 72 h, and proliferating stem cells remained preserved. Using Dmed, hPCS also remained viable for up to 72 h, and specifically rescued the metabolizing enterocytes during culture. In conclusion, by using two different organoid culture media, we could extend the hPCIS viability for up to 72 h of incubation and specifically steer stem cells or enterocytes towards their original function, metabolism, and proliferation, potentially allowing pharmacokinetic and toxicology studies beyond the 24 h timeframe.

Development of a self-limiting model of methotrexate-induced mucositis reinforces butyrate as a potential therapy.

Gastrointestinal mucositis is a complication of anticancer treatment, with few validated in vitro systems suitable to study the complex mechanisms of mucosal injury. Therefore, we aimed to develop and characterize a chemotherapeutic-induced model of mucositis using 3D intestinal organoids. Organoids derived from mouse ileum were grown for 7 days and incubated with different concentrations of the chemotherapeutic agent methotrexate (MTX). Metabolic activity, citrulline levels and cytokine/chemokine production were measured to determine the optimal dosage and incubation time. The protective effects of folinic acid on the toxicity of MTX were investigated by pre-treating organoids with (0.0005-50 µg/mL) folinic acid. The impact of microbial-derived short-chain fatty acids was evaluated by supplementation with butyrate in the organoid model. MTX caused a dose-dependent reduction in cell metabolic activity and citrulline production that was salvaged by folinic acid treatment. Overall, MTX causes significant organoid damage, which can be reversed upon removal of MTX. The protective effect of folinic acid suggest that the organoids respond in a clinical relevant manner. By using the model for intervention, it was found that prophylactic treatment with butyrate might be a valuable strategy for prophylactic mucositis prevention.

[Hypokalemia due to a liquorice-containing thirst-quencher]. / Pseudohyperaldosteronisme door Arabische dorstlesser.

BACKGROUND: Liquorice consumption can cause pseudohyperaldosteronism and potentially lead to life-threatening complications. Besides correcting hypokalemia and hypertension, finding the triggering factor for pseudohyperaldosteronism is essential to prevent recurrence. CASE DESCRIPTION: A 68-year-old Syrian man presented in the Emergency Department with complaints of fatigue, weakness and exercise-related shortness of breath. Blood tests revealed severe hypokalemia for which suppletion and cardiac rhythm surveillance was necessary. Talking to the patient's son, it occurred that our patient drank copious amounts of Erk Sous, a thirst-quenching drink made from liquorice. The diagnosis pseudohyperaldosteronismwas confirmed by a high level of glycyrrhetinic acid in the patient's urine. After correction of the hypokalemia, our patient recovered successfully. CONCLUSION: Erk Sous is a thirst-quenching drink that can cause pseudohyperaldosteronism. The drink is popular in the Middle East during summer and Ramadan. If a patient from the Middle East presents with hypokalemia and/or hypertension, ask for consumption of Erk Sous.

Recommendations for the successful control of a large outbreak of vancomycin-resistant Enterococcus faecium in a non-endemic hospital setting.

BACKGROUND: A large outbreak of three epidemic vancomycin-resistant Enterococcus faecium (VRE) clones affected the study hospital for almost two years. AIM: To describe the strategy to successfully control this outbreak and eradicate VRE from the study hospital. METHODS: Infection control interventions started after detection of VRE in three patients. Hospital-wide surveillance was started after ongoing transmission despite isolation precautions, cleaning and contact tracing. Hygiene education and discipline were enhanced. Despite these interventions, additional measures were required to control the outbreak, such as ward disinfection with hydrogen peroxide vapour and the introduction of a VRE quarantine ward. Ultimately, ciprofloxacin prophylaxis for haematological patients on chemotherapy was abandoned. FINDINGS: Over a 22-month period, 242 VRE carriers were identified. Of these, 128 (53%) patients were detected by hospital-wide surveillance alone. Three epidemic clones were detected: ST494-vanA (N = 160), ST78-vanA (N = 23) and ST117-vanB (N = 32). In total, 5614 possible contacts were identified. VRE transmission occurred on 13 out of 23 wards. VRE was cultured from clinical specimens in 22 patients (seven with bacteraemia). Since January 2014, no further transmission of these VRE clones has been observed. CONCLUSION: Infection control measures according to international guidelines were insufficient to expose the outbreak to its full extent and control it. Its full extent only became apparent after sustained hospital-wide screening. Successful control of this hospital-wide VRE outbreak was feasible, but required great effort. Final containment and eradication of the epidemic clones was achieved by environmental decontamination with hydrogen peroxide vapour, strict isolation precautions, a VRE quarantine ward and antimicrobial stewardship.

Substrain and light regime effects on integrated anxiety-related behavioral z-scores in male C57BL/6 mice-Hypomagnesaemia has only a small effect on avoidance behavior.

Magnesium (Mg) has been described to possess an anxiolytic function, but a number of studies present inconsistent results on this matter. In this study the effect of Mg deficiency on anxiety-related behavior, brain and blood plasma Mg in young adult male C57BL/6JOlaHsd and C57BL/6NCrl mice was studied. The animals were put on a control or Mg deficient diet from day 0 and significant hypomagnesaemia was evident from day 12 onwards in the test animals. Housing and test conditions were under either conventional light regime (white light behavioral test conditions) or reverse light regime (red light behavioral test conditions). The animals were tested in three tests for unconditioned anxiety: the modified Hole Board (day 14), the light-dark test (day 21) and the elevated plus maze (day 28). Overall integrated behavioral z-scores were calculated over these three behavioral tests. Mg showed a structure dependent distribution at the level of the brain, that differed between C57BL/6 substrain and light regime (conventional versus reverse), respectively. Likewise, total brain Mg did differ between substrain and light regime, but was not affected by the diet. Animals on the Mg deficient diet housed under conventional light regime had a higher final (day 28) blood plasma corticosterone level as compared to controls. Animals housed under reverse light regime exhibited no diet effect of plasma corticosterone levels. The significant hypomagnesaemia at blood plasma level resulted in an effect of Mg deficiency on avoidance, but not overall anxiety-related behavior. Significant differences regarding avoidance behavior were found between the two substrains and light regimes, respectively.

Pannexin1 in the outer retina of the zebrafish, Danio rerio.

In the retina, chemical and electrical synapses couple neurons into functional networks. New candidates encoding for electrical synapse proteins have recently emerged. In the present study, we determined the localization of the candidate protein pannexin1 (zfPanx1) in the zebrafish retina and studied the functional properties of zfPanx1 exogenously expressed in Neuroblastoma 2a (N2a) cells. zfPanx1 was identified on the surface of horizontal cell dendrites invaginating deeply into the cone pedicle near the glutamate release sites of the cones, providing in vivo evidence for hemichannel formation at that location. This strategic position of zfPanx1 in the photoreceptor synapse could potentially allow modulation of cone output. Using whole cell voltage clamp and excised patch recordings of transfected N2a cells, we demonstrated that zfPanx1 forms voltage-activated hemichannels with a large unitary conductance in vitro. These channels can open at physiological membrane potentials. Functional channels were not formed following mutation of a single amino acid within a conserved protein motif recently shown to be N-glycosylated in rodent Panx1. Together, these findings indicate that zfPanx1 displays properties similar to its mammalian homologues and can potentially play an important role in functions of the outer retina.

The prenatal development of the human orbit.

During the 1970s, as part of his work for a doctor's thesis in which he described the development of the human orbit in great detail, the first author established the largest anatomical collection of embryonic and fetal orbits ever. Unfortunately, he died before the thesis could be finished. The thousands of sections have now been scanned at high resolution and made publicly available on the Internet at www.visible-orbit.org; 3-D reconstruction software is being developed. The Discussion and part of the 'Methods' section of this thesis are published in translation in this article. The conclusions of the first author at the time read as follows: (1) initially, the developing orbit is vaguely indicated by condensations in the mesenchymal connective tissue area; (2) in this connective tissue area, chondral, osseous and muscular structures develop and grow until, in the fully developed stage, the orbital content is surrounded by bony surfaces with a thin layer of connective tissue as periosteum, and by a muscle fragment; (3) the embryonic and early fetal phase, during which one can only speak of a 'regio orbitalis,' is followed by a period in which we can speak of a primordial orbit; (4) the phase of the primordial orbit extends until after birth; (5) the surface area of all orbital walls increases more or less linearly; (6) the 'musculus orbitalis Mülleri' occupies a special place in the orbital wall; (7) the so-called 'regio craniolateralis' is the primordium, which, in the fully developed stage, is occupied by the thick intersection of the frontolateral and the horizontal part of the frontal bone; (8) in the frontal plane, the shape of the primordial orbit, as well as that of the fully developed orbit, is more or less round; (9) the prenatal development of an eye socket is a complex event, characterized by changes in composition, shape and size of the orbital wall; and (10) the orbit can only be denoted by the term "eye socket" when it is fully developed. At the end of the thesis, he also presented the following postulates: (1) in the prenatal orbit, the development of the so-called 'periorbita' is at the forefront; (2) the mutual rotation of the orbital axes and the frontalization of the eyes from approx. 180 degrees in the early prenatal stages to approx. 50 degrees in adulthood do not seem to be caused by mechanical influences of the surrounding tissue; (3) the pterygopalatine fossa and the 'cavum cerebri' are not part of the orbit at any developmental stage; (4) in the prenatal skull, the inferior nasal concha, which forms part of the maxilla in the fully developed skull, is part of the 'capsula nasalis'; and (5) in order to achieve normal development of the eye socket in microphthalmus and anophthalmus, the normal orbital content should be restored.

Severe hypokalaemic paralysis and rhabdomyolysis due to ingestion of liquorice.

Chronic ingestion of liquorice induces a syndrome with findings similar to those in primary hyperaldosteronism. We describe a patient who, with a plasma K+ of 1.8 mmol/l, showed a paralysis and severe rhabdomyolysis after the habitual consumption of natural liquorice. Liquorice has become widely available as a flavouring agent in foods and drugs. It is important for physicians to keep liquorice consumption in mind as a cause for hypokalaemic paralysis and rhabdomyolysis.

The involvement of glutamate-gated channels in negative feedback from horizontal cells to cones.

Photoreceptors are the light sensitive cells in the retina. They project to horizontal cells and bipolar cells via a glutamatergic feed forward pathway. Horizontal cells are strongly electrically coupled and integrate in that way the input from the photoreceptors. Horizontal cells feedback to cones negatively. The combined signal from the photoreceptors and the horizontal cells is sent to the bipolar cells. The feedback pathway from horizontal cells to cones is thought to form the basis for the center/surround organization of bipolar cells. The nature of the feedback pathway is an issue of intense debate. It was thought for a long time that this feedback pathway was GABAergic, because cones have GABA-receptors and horizontal cells release GABA via a GABA-transporter working in the reversed direction. However, recently we showed in goldfish that horizontal cells feed back to cones via an alternative mechanism. In goldfish, negative feedback from horizontal cells to cones shifts the calcium current of the cone to more negative potentials. This feedback pathway is independent of GABA, since feedback cannot be blocked by either saturating concentrations of PTX, the GABA-transporter blocker SKF89976A, or application of GABA. The mechanism of negative feedback from horizontal cells to cones involves hemichannels located at the tips of the invaginating horizontal cells, just opposite to the calcium channels of the cones. Current flowing through these hemichannels changes the extracellular potential deep in the synaptic cleft and in that way modulates the calcium current of the cones. Such a modulation of the extracellular potential is called ephaptic. If negative feedback from horizontal cells to cones is indeed ephaptic, other channels present in the synapse should also be able to act as a current source, i.e., should also be able to change the output of the cone. We showed that glutamate-gated channels present at the tips of the horizontal cell dendrites can also mediate feedback responses. Surprisingly, although the glutamate-gated conductance of the horizontal cells is eight times the hemichannel conductance, glutamate-gated channels are not the major current source in negative feedback from horizontal cells to cones. In this chapter we present evidence that this is due to the more focal localization of the hemichannels, compared to a diffuse and extrasynaptic localization of the glutamate-gated channels.

A medical mystery. Lead poisoning.

A 25-year-old schizophrenic man presented with abdominal pain, nausea, vomiting, weight loss and anaemia. He was noted to be malnourished with generalised muscle atrophy. Laboratory investigations showed Hb 4.7 mmol/L, MCV 80fl, bilirubin 75 micromol/L and reticulocyte count 93 percent. Peripheral blood films showed anisocytosis, basophilic stippling and Cabot's rings. Electromyography confirmed typical motor nerve neuropathy. The clinical and laboratory findings were that of lead poisoning. The patient was later found to be ingesting lead-containing paint. He was treated with lead-chelating agents.

Bronchocentric granulomatosis associated with influenza-A virus infection.

Bronchocentric granulomatosis is an unusual pathologic entity that is characterized by a necrotizing granulomatous inflammation surrounding the airways. The diagnosis is usually made retrospectively, after histopathologic examination of an open-lung biopsy or resection of a pulmonary lesion. Although the aetiology has not been fully elucidated, the current pathogenetic mechanism is considered to be an immunologic reaction against endobronchial antigens, since most patients exhibit signs of bronchial asthma, eosinophilia and allergic bronchopulmonary aspergillosis. However, non-asthmatic patients may develop bronchocentric granulomatosis without signs for endobronchial fungal infections, but probably as a consequence of other pulmonary infections. An 80-year-old female patient presented with high fever and bilateral pulmonary infiltrates and nodules. After extensive investigations and open-lung biopsy, the diagnosis bronchocentric granulomatosis was established that was possibly associated with an influenza-A virus infection. Treatment consisted of immunosuppressive drugs (prednisone and cyclophosphamide), which led to complete clinical and radiological recovery.

Disseminated tuberculosis, pulmonary aspergillosis and cutaneous herpes simplex infection in a patient with infliximab and methotrexate.

CASE PRESENTATION: Despite chemoprophylaxis with isoniazid a 58-year-old Creole patient with mild rheumatoid arthritis developed disseminated tuberculosis, pulmonary aspergillosis and cutaneous herpes simplex infection during treatment with infliximab and methotrexate. TREATMENT: The patient received antituberculous drugs (ethambutol, isoniazid, pyrazinamide, rifampicin), amphotericin B, flucytosine, and valaciclovir, along with prolonged intensive care treatment and mechanical ventilation. CONCLUSIONS: The present case confirms that isoniazid prophylaxis (300 mg once daily, during 6 months) does not protect against the reactivation and dissemination of latent tuberculosis. It also shows that combined treatment with infliximab and methotrexate may induce severe immunosuppression with prolonged leukocytopenia and depressed cellular immunity, leading to multiple opportunistic infections. Extensive diagnostic testing, early start of antimicrobial therapy and enteral immunonutrition, and further infection prevention with selective decontamination of the digestive tract may have been the key to a good clinical outcome.

[Hereditary hyperferritinaemia-cataract syndrome]. / Hereditair hyperferritinemie-cataractsyndroom.

A 67-year-old woman and a 22-year-old man, great aunt and great nephew, were examined because of hyperferritinaemia; both had been operated during adolescence for bilateral cataract. The clinical diagnosis 'hereditary hyperferritinaemia-cataract syndrome' (HHCS) was confirmed after DNA-analysis, which showed a point mutation in the L-ferritin gene on chromosome 19 (32G > A, the previously reported Pavia-1 mutation). The further supervision of the patients consisted of reassurance, providing an explanation about the background of HHCS and how it differs from HFE-gene related haemochromatosis, and informing other family members. Both patients were referred back to their general practitioners. HHCS is an autosomal dominant disorder that is characterised by elevated serum ferritin in the absence of iron overload. The dysregulation of ferritin production is caused by heterogenous mutations in the iron responsive element of the L-ferritin gene on chromosome 19, which reduce the binding of iron-regulatory proteins. This results in exaggerated L-ferritin mRNA translation, which is normally tightly controlled by the intracellular iron availability. The only relevant clinical symptom is early-onset, bilateral cataract, which is due to L-ferritin deposits in the stroma of the lens. Internists and haematologists should differentiate this syndrome from haemochromatosis in order to avoid invasive diagnostics and mistreatment. Ophthalmologists should consider this syndrome in patients with congenitial or juvenile cataract.

[Diagnostic image (159). An elderly woman with shock and discoloration of an upper leg. Gas gangrene caused by C. septicum]. / Diagnose in beeld (159). Een bejaarde vrouw met shock en met een verkleurd bovenbeen. Gasgangreen veroorzaakt door C. septicum.

In an 80-year-old woman septic shock and gas gangrene were diagnosed secondary to a perforated carcinoma of the coecum.

[Diagnostic image (133) A man with schizophrenia and anemia. Lead poisoning]. / Diagnose in beeld (133). Een man met schizofrenie en anemie. Loodintoxicatie.

A 25-year-old man with schizophrenia had abdominal complaints and haemolytic anaemia, basophilic stippling and Cabot's rings due to lead poisoning.

The molecular basis of co-evolution between Cladosporium fulvum and tomato.

Cladosporiumfulvum is a semi-biotrophic pathogen, which causes leaf mold of tomato (Lycopersicon spp.). In our laboratory this pathosystem serves as a model to study gene-for-gene interactions between plants and pathogenic fungi (Joosten & De Wit 1999). Many avirulence (Avr) genes and matching resistance (CQ) genes have been cloned and we are now beginning to understand how their products can induce an array of plant defense responses, including the classic hypersensitive response (HR). Here, we will discuss the latest results of our molecular studies on this interaction. These include the isolation of: (i) two new Avr genes, Avr2 and Avr4E, (ii) the determination of the specificity determinants within the Cf-4 and Cf-9 genes by artificial domain swaps and introduction of point mutations, (iii) the analysis of polymorphism occurring in AVR9-responsive Cf genes occurring in natural populations of L. pimpinellifolium, and finally (iv) the description of an efficient method to identify early HR-related genes.