Extracellular recording of glycine receptor chloride channel activity as a prototype for biohybrid sensors

There is a continuously growing scientific and technological interest to develop and improve the application of artificial sensors. Biological components which are capable to transduce neutral signals into specific, robust and reproducible indicators frame an attractive alternative to construct biohybrid sensors. Since naturally "occurring" biosensors are only sparsely compatible with artificial devices, genetic engineering of eukaryotic cells provides an attractive approach, where cells can be tailored such to detect target compounds with exquisite specificity and sensitivity. We have developed the prototype for a single-cell-based anion-selective biohybrid sensor. HEK293 cells were stably transfected with a gene encoding glycine receptor alpha(1) subunits. These cells were employed as transducers for glycine-evoked chloride currents in a concentration-dependent way. Cultured on substrate-integrated micro-devices, anionic membrane currents of cells were monitored extracellularly with field-effect transistors (FETs) and gold microelectrode arrays (MEAs). The results supported predictions of state-of-the-art models for cell-sensor coupling mechanisms and confirmed that extracellularly recorded anion currents cause similar signals, regardless whether obtained with field-effect transistors or microelectrodes. The whole-cell sensor successfully tracked glycine concentrations differing by three orders of magnitude. To our knowledge this contribution for the first time marks the functional characterization of an anion-selective biohybrid sensor.

[Laboratory changes in anorexia nervosa]

To correctly diagnose a patient with anorexia nervosa, medical history according to DSM-IV or ICD-10 criteria and the physical examination is essential. Furthermore, it is useful for a physician to have knowledge regarding typical alteration in laboratory parameters of anorectic patients to realize diagnostical hints. Typical laboratory changes, although not exclusively seen in anorexia nervosa, include hyponatremia, hypokalemia, hypochloremia, liver enzyme elevation, and low red and white blood cell count. The hormones leptin, neuropeptide Y (NPY), triiodothyronine (T3), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and oestrogen are usually below the normal range, whereas ghrelin, pancreatic polypeptide (PP), tumor necrosis factor-alpha (TNF-alpha) and cortisol levels are reported to be typically elevated.

Inverse agonist and neutral antagonist actions of synthetic compounds at an insect 5-HT1 receptor

BACKGROUND AND PURPOSE

5-Hydroxytryptamine (5-HT) has been shown to control and modulate many physiological and behavioural functions in insects. In this study, we report the cloning and pharmacological properties of a 5-HT(1) receptor of an insect model for neurobiology, physiology and pharmacology.

EXPERIMENTAL APPROACH

A cDNA encoding for the Periplaneta americana 5-HT(1) receptor was amplified from brain cDNA. The receptor was stably expressed in HEK 293 cells, and the functional and pharmacological properties were determined in cAMP assays. Receptor distribution was investigated by RT-PCR and by immunocytochemistry using an affinity-purified polyclonal antiserum.

KEY RESULTS

The P. americana 5-HT(1) receptor (Pea5-HT(1)) shares pronounced sequence and functional similarity with mammalian 5-HT(1) receptors. Activation with 5-HT reduced adenylyl cyclase activity in a dose-dependent manner. Pea5-HT(1) was expressed as a constitutively active receptor with methiothepin acting as a neutral antagonist, and WAY 100635 as an inverse agonist. Receptor mRNA was present in various tissues including brain, salivary glands and midgut. Receptor-specific antibodies showed that the native protein was expressed in a glycosylated form in membrane samples of brain and salivary glands.

CONCLUSIONS AND IMPLICATIONS

This study marks the first pharmacological identification of an inverse agonist and a neutral antagonist at an insect 5-HT(1) receptor. The results presented here should facilitate further analyses of 5-HT(1) receptors in mediating central and peripheral effects of 5-HT in insects.

Cell surface tetraspanin Tspan8 contributes to molecular pathways of exosome-induced endothelial cell activation

Tumor-derived exosomes containing the tetraspanin Tspan8 can efficiently induce angiogenesis in tumors and tumor-free tissues. However, little information exists on exosome-endothelial cell (EC) interactions or the proangiogenic role of tetraspanins, which are a constitutive component of exosomes. In this study, we used a rat adenocarcinoma model (AS-Tspan8) to explore the effects of exosomal Tspan8 on angiogenesis. Tspan8 contributed to a selective recruitment of proteins and mRNA into exosomes, including CD106 and CD49d, which were implicated in exosome-EC binding and EC internalization. We found that EC internalized Tspan8-CD49d complex-containing exosomes. Exosome uptake induced vascular endothelial growth factor (VEGF)-independent regulation of several angiogenesis-related genes, including von Willebrand factor, Tspan8, chemokines CXCL5 and MIF, chemokine receptor CCR1, and, together with VEGF, VEGF receptor 2. EC uptake of Tspan8-CD49d complex-containing exosomes was accompanied by enhanced EC proliferation, migration, sprouting, and maturation of EC progenitors. Unraveling these new pathways of exosome-initiated EC regulation could provide new options for therapeutic interference with tumor-induced angiogenesis.

Mechanism of bubble coalescence induced by surfactant covered antifoam particles

Mechanism of inter-bubble coalescence by an aqueous fatty alcohol particle suspension antifoam containing a nonionic surfactant has been investigated. By observing visually two colliding air bubbles in a liquid pool in the presence of the antifoam, a four-step mechanism is identified. The role of the surfactant in the antifoam is, for the first time, proposed. A surface tension gradient due to the local surfactant concentration difference enables a surfactant laden hydrophobic particle located on bubble surface to move from the periphery of a liquid film between two colliding air bubbles to their region of contact. Drop volume tensiometry and macroscopic foam column experiments are used to further prove this observation. Subsequently, the particle bridges and dewets the bubbles resulting in film rupture. The rate of drainage of the liquid film depends on the particle hydrophobicity, which necessitates complete surfactant desorption from particle surface. This is corroborated experimentally by Wilhelmy plate tensiometry. In addition, cryo-scanning electron and atomic force microscopy are used to determine the particle shape and the force for its entry into the bubble.

A microfluidic chip for electrochemical conversions in drug metabolism studies

We have designed a microfluidic microreactor chip for electrochemical conversion of analytes, containing a palladium reference electrode and platinum working and counter electrodes. The counter electrode is placed in a separate side-channel on chip to prevent unwanted side-products appearing in the measured spectrograms. Using this chip, cyclic voltammograms are measured in volumes of 9.6 nL. Furthermore the conversion efficiency of ferricyanide is characterized using UV/vis-spectroscopy. We have obtained an on-line conversion of 97% using a flow rate of 1 microL/min. We have used the microreactor chip to study the electrochemical metabolism pathway of amodiaquine using electrochemistry (EC)-liquid chromatography (LC)-mass spectrometry (MS). We have compared our results with measurements obtained with commercially available electrochemical flow-through cells. Using our chip it was possible to obtain similar results. Therefore, we have fabricated an electrochemical cell on-chip which is used successfully in EC-UV/vis and EC-LC-MS experiments.

[Deleterious role of hyperthermia in neurocritical care]

Fever is a secondary brain injury and may worsen neurological prognosis of neurological intensive care unit (NICU) patients. In response to an immunological threat, fever associates various physiological reactions, including hyperthermia. Its definition may vary but the most commonly used threshold is 37.5 degrees C. In animal studies, hyperthermia applied before, during or after cerebral ischemia may increase the volume of ischemic lesions. The mechanism of this effect may include increase in blood brain barrier permeability, increase in excitatory amino acid release and increase in free radical production. In NICU patients, fever is frequent, occurring in up to 20-30% of patients. Moreover, after haemorrhagic stroke, fever has been reported in 40-50% of patients. In half of the patients, fever may be related to an infectious cause but in more than 25% of patients, hyperthermia may be of central origin. After ischemic stroke, hyperthermia during the first 72 hours is associated with an increase in infarct size and increase in morbidity and mortality. This holds true also after subarachnoid haemorrhage. After traumatic brain injury, fever is not related to mortality but may increase morbidity. Whereas no causal link has been established between fever and unfavourable outcome, it seems reasonable to treat hyperthermia in patients suffering from brain injuries. In such patients, antipyretics have a moderate efficacy. In case of failure, they should be replaced by physical cooling techniques.

Continuous intravenous lidocaine in the treatment of paralytic ileus due to severe spinal cord injury

Paralytic ileus is a major concern in the acute phase of spinal cord injury. Classical treatment with neostigmine is often ineffective. Continuous intravenous (i.v.) lidocaine infusion has been previously proposed intra and post-operatively in order to decrease the duration of post-operative ileus after abdominal surgery. We report the cases of seven patients suffering from complete paralytic spinal cord injury-related ileus with colectasy resistant to neostigmine, who were treated by i.v. lidocaine infusion.

[Transfusion in neurosurgery]

In neurosurgery, the question of the optimal transfusion "trigger" remains a controversial matter. Regarding the brain, the current data are still incomplete, justifying the continuation of experimental and clinical studies. The existing expert advices are based on these rather poor data and would probably evolve after the completion of clinical studies in progress. In spine surgery, the situation is simpler and the transfusional stakes are quite similar to those of orthopedics and traumatology. With regard to hemostasis, standardized recommendations exist depending on the laboratory test results or the anticoagulant treatments of the patient.

A novel therapeutic option in Cogan diseases? TNF-alpha blockers

Cogan's syndrome is characterized by noninfectious, interstitial keratitis combined with a vestibulo-auditory deficit. Despite therapy with corticosteroids in combination with immunosuppressive agents, relapses occurred in two subjects and the clinical course suggested a progression of the disease. Treatment with anti-TNF-alpha was started leading to a rapid and sustained clinical remission for over 2 respectively 3 years.

Population pharmacokinetics-pharmacodynamics of alemtuzumab (Campath) in patients with chronic lymphocytic leukaemia and its link to treatment response

AIMS

To characterize alemtuzumab pharmacokinetics and its exposure-response relationship with white blood cell (WBC) count in patients with B-cell chronic lymphocytic leukaemia (CLL).

METHODS

Nonlinear mixed effects models were used to characterize plasma concentration-time data and WBC count-time data from 67 patients. Logistic regression was used to relate summary measures of drug exposure to tumour response.

RESULTS

Alemtuzumab pharmacokinetics were best characterized by a two-compartment model with nonlinear elimination where V(max) (microg h(-1)) was [1020 x (WBC count/10 x 10(9) l(-1))(0.194)], K(m) was 338 microg l(-1), V(1) was 11.3 l, Q was 1.05 l h(-1) and V(2) was 41.5 l. Intersubject variability (ISV) in V(max), K(m), V(1) and V(2) was 32%, 145%, 84% and 179%, respectively. The reduction in WBC over time was modelled by a stimulatory loss indirect response model with values of 18.2 for E(max), 306 microg l(-1) for EC(50), 1.56 x 10(9) cells l(-1) h(-1) for K(in) and 0.029 per h for K(out). The probability of achieving a complete or partial response was >/=50% when the maximal trough concentration exceeded 13.2 microg ml(-1) or when AUC(0-tau) exceeded 484 microg h(-1) ml(-1).

CONCLUSIONS

Alemtuzumab displayed time- and concentration-dependent pharmacokinetics with large interpatient variability, both in pharmacokinetics and pharmacodynamics, which was probably reflective of differences in tumour burden among patients. A direct relationship between maximal trough concentrations and clinical outcomes was observed, with increasing alemtuzumab exposure resulting in a greater probability of positive tumour response.

Veränderungen in der sozialen Distanz der Bevölkerung gegenüber schizophren Erkrankten in 6 deutschen Großstädten

BACKGROUND

In several German cities various programmes and initiatives have been conducted during recent years aimed at reducing the stigma attached to mental illness, especially schizophrenia. So far only single interventions in specific target groups have been evaluated but not their effectiveness in the general population.

METHODS

Two representative telephone surveys with repeated measurements were conducted in six German cities (n 7,225/4,622). Social distance towards people with schizophrenia and knowledge of antistigma projects were assessed.

RESULTS

Between 2001 and 2004 the social distance toward persons with schizophrenia decreased in the general population. Persons familiar with antistigma projects or who lived in cities with such projects showed lower social distance.

CONCLUSIONS

For the first time evidence has been found that antistigma interventions are successful in reducing the stigma attached to schizophrenia in the general population.

Neurogenic pulmonary edema

Neurogenic pulmonary edema (NPE) is usually defined as an acute pulmonary edema occurring shortly after a central neurologic insult. It has been reported regularly for a long time in numerous and various injuries of the central nervous system in both adults and children, but remains poorly understood because of the complexity of its pathophysiologic mechanisms involving hemodynamic and inflammatory aspects. NPE seems to be under-diagnosed in acute neurologic injuries, partly because the prevention and detection of non-neurologic complications of acute cerebral insults are not at the forefront of the strategy of physicians. The presence of NPE should be high on the list of diagnoses when patients with central neurologic injury suddenly become dyspneic or present with a decreased P(a)o(2)/F(i)o(2) ratio. The associated mortality rate is high, but recovery is usually rapid with early and appropriate management. The treatment of NPE should aim to meet the oxygenation needs without impairing cerebral hemodynamics, to avoid pulmonary worsening and to treat possible associated myocardial dysfunction. During brain death, NPE may worsen myocardial dysfunction, preventing heart harvesting.

Amphotericin B nasal spray has no effect on nasal polyps

Nasal polyps and chronic rhinosinusitis are the products of an inflammatory process. Recently, fungal involvement has been thought to stimulate the development of polyps, and administration of antifungal agents was therefore considered a potential treatment. Several studies have been published indicating amphotericin B as an effective treatment for nasal polyps and chronic rhinosinusitis. The aim of our investigation was to evaluate the efficacy of intranasal applied amphotericin B on the growth of nasal polyps in a three-month, prospective, open trial. Our results show that nasal amphotericin B spray is not effective for nasal polyps and may even cause deterioration.

Lebensqualität und Zufriedenheit nach Brustrekonstruktion

BACKGROUND

Nowadays, the array of methods for reconstruction of the female breast following mastectomy is vast. In this study, we investigate and compare quality of life after breast reconstruction and satisfaction with the results of two commonly used techniques (autologous tissue vs. expander/implant).

METHODS

Ninety-one consecutive patients who underwent breast reconstruction at a German clinic between 1996 and 2001 were included in the study. Patient satisfaction and quality of life were assessed retrospectively using self-evaluation questionnaires.

RESULTS

Patients were generally more satisfied with the outcome of the operation when autologous tissue was used. This was significant in the following areas: breast size, form, definition of the lower breast fold, softness of the breast, and symmetry of the breasts. In both groups the quality of life following breast reconstruction at least 2 years after the operation was equal to that of healthy women of the same age group.

CONCLUSION

Although patients were more satisfied with the results of autologous breast reconstruction, procedure choice did not affect quality of life.

Dysgnathia, orthognathic surgery and spinal posture

The aim of this study was to evaluate the spine by video rasterstereography before and after orthognathic surgery. Twenty-nine patients (17 patients with a skeletal class III, 7 patients with a skeletal class II, and 5 patients with mandibular asymmetry) were evaluated preoperatively and 1 year postoperatively. Video rasterstereography is a method of back surface measurement and shape analysis using the moire topography. Orthognathic surgery in cases of class III and asymmetry did not lead to significant changes in body posture. In class II patients it led to some changes in body posture, but without orthopaedic consequences. It is concluded that orthognathic surgery causes minimal or no change in body posture.