High-temperature operation of electrical injection type-II (GaIn)As/Ga(AsSb)/(GaIn)As "W"-quantum well lasers emitting at 1.3 µm

Electrical injection lasers emitting in the 1.3 μm wavelength regime based on (GaIn)As/Ga(AsSb)/(GaIn)As type-II double "W"-quantum well heterostructures grown on GaAs substrate are demonstrated. The structure is designed by applying a fully microscopic theory and fabricated using metal organic vapor phase epitaxy. Temperature-dependent electroluminescence measurements as well as broad-area edge-emitting laser studies are carried out in order to characterize the resulting devices. Laser emission based on the fundamental type-II transition is demonstrated for a 975 μm long laser bar in the temperature range between 10 °C and 100 °C. The device exhibits a differential efficiency of 41 % and a threshold current density of 1.0 kA/cm2 at room temperature. Temperature-dependent laser studies reveal characteristic temperatures of T0 = (132 ± 3) K over the whole temperature range and T1 = (159 ± 13) K between 10 °C and 70 °C and T1 = (40 ± 1) K between 80 °C and 100 °C.

[Patients' experiences of orgasm changes and loss of ejaculation after radical prostatectomy]

Patients' experiences of orgasm changes and loss of ejaculation after radical prostatectomy   In this study we report on men's experiences of orgasm changes and loss of ejaculation after radical prostatectomy. Ten men, all recruited through a Swedish hospital, were interviewed and data was analyzed using qualitative content analysis. The results showed that the experience of orgasm has weakened but that the loss of ejaculation was not perceived as a loss per se. However, the risk of urine release during orgasm was troublesome and inhibiting. These challenges were framed within an existential narrative about sexuality, as expressed in preoperative sexual farewell rituals and postoperative feelings of ambivalence and regret. These findings can be used in the design of patient information and for sexual rehabilitation treatment.

Salivary gland scintigraphy in patients suffering from severe keratoconjunctivitis sicca. Evaluation of the viability of submandibular glands before and after transfer into the temporal fossa

Low tear production or elevated tear evaporation can lead to severe keratoconjunctivitis sicca. In patients with this disease, the transfer of an autologous submandibular gland into the temporal fossa is currently the most common surgical lacrimal gland substituting procedure.

AIM

We compared the pre- and postoperative viability of transferred submandibular glands.

PATIENTS, METHODS

Altogether 16 submandibular glands had been transferred in 12 patients. The graft's viability was evaluated before and 0.5-1, 1-6 and 8-12 months after transplantation by dynamic salivary gland scintigraphies after application of 40-50 MBq 99mTc-pertechnetate. Quantitative analysis was performed by calculation and comparison of the glandula submandibularis-to-background-ratio (SBR) and the transplant-to-background-ratio (TBR). The scintigraphic results were correlated with the clinical follow-up.

RESULTS

All grafts remained viable during clinical follow-up. Salivary gland scintigraphy yielded 15 true positive results and 1 false-negative result. Comparison of presurgical SBR and postsurgical TBR showed good correlation with the clinical course. In 10 patients at least one transplant-reduction was necessary due to excessive epiphora occurring averagely 8 months after transplantation.

CONCLUSION

Our results show that salivary gland scintigraphy very exactly reflects the morphological and biochemical postsurgical changes in a transferred submandibular gland. Thus, it is a reliable tool to exactly and objectively evaluate the viability of the grafts in the postsurgical course.

[Trabeculectomy versus canaloplasty--utility and cost-effectiveness analysis]

PURPOSE

Due to increasing cost pressure in the public health system treatments and their costs are highly relevant in the therapy for chronic diseases such as glaucoma. In the era of diagnosis-related group (DRG) reimbursement, new interventions need to prove not only their safety and effectiveness but also their cost-utility. Canaloplasty as a new interventional surgery is compared to trabeculectomy (TE) by means of a cost and effort analysis.

METHODS

In this retrospective, consecutive case series patients were compared as follows: group I, 21 eyes of 21 patients undergoing canaloplasty from 2009 on and group II, 48 eyes of 42 patients, who were treated with TE with mitomycin C (MMC) from 2001 to 2004 and had intensified postoperative care. Data regarding demography, duration of hospitalisation, duration of surgery, surgical complications and interventions, and pre- and post-operative IOP were analysed within the first 6 months post operation.

RESULTS

In group I mean duration of hospitalisation was 5.3 ± 0.8 days (d) and in group II 10.7 ± 2.8 d. Duration of surgery was 77 ± 14 min in group I and in group II 48 ± 11 min. On average 2.8 ± 1.0 visits were needed during follow-up in group I and 6 ± 1.5 visits in group II. The mean preoperative IOP of 28.75 ± 9.6 mmHg was lowered to 12.8 ± 3.3 mmHg after six months in group I and in group II from 34.5 ± 13.4 mmHg to 10.3 ± 4.5 mmHg. In group I, a total of 4 interventions were seen within the first six months without re-admission. In group II 107 interventions and eleven re-admissions were necessary. Mean costs for hospitalisation amount to 821.50 € in group I and 1658.50 € in group II. Overall expenses were 2379.62 € for canaloplasty and 2733.61 € for TE.

CONCLUSION

Both interventions could effectively control IOP. However, trabeculectomy requires a longer hospitalisation, has higher re-admission rates and needs more frequent postoperative controls, which makes TE more costly and time-consuming than canaloplasty.

High Quality Ion Channel Analysis on a Chip with the NPC© Technology

In evaluating ion channel function, electrophysiology, e.g., patch clamping, provides the highest information content. For the analysis of ion channel-modulating compounds, one variant of the patch-clamp technique, the whole-cell configuration, is particularly useful. We present here patch-clamp recordings in the whole-cell configuration and single channel recordings performed with planar patch-clamp chips, which are microstructured from borosilicate glass substrate. The chips are used in the Port-a-Patch, an ion channel research/screening instrument that enables automated patch-clamp experiments on a single cell. A software runs the experiment by executing user-determined protocols for cell positioning, as well as for electrical stimulation and current readout. In various electrophysiological experiments, the high quality of recordings and the versatility of the perfusion of the recorded cells are demonstrated. Quantitative pharmacological experiments are performed on sodium channels expressed in HEK cells using solution volumes in the low microliter range. The exceptionally low volume consumption in the experiments make the system attractive for work on rare or expensive compounds. Due to the low volumes necessary, a rapid solution exchange is facilitated, which is shown on RBL cells. The patch-clamp chip enables a rapid and precise perfusion, allowing sophisticated investigations on ion channel function with the Port-a-Patch.

A kinetic study on the stereospecific inhibition of KCNQ1 and I(Ks) by the chromanol 293B

1. Recently we and others have demonstrated a stereoselective inhibition of slowly activating human I(Ks) (KCNQ1/MinK) and homomeric KCNQ1 potassium channels by the enantiomers of the chromanol 293B. Here, we further characterized the mechanism of the 293B block and studied the influence of the 293B enantiomers on the gating kinetics of both channels after their heterologous expression in Xenopus oocytes. 2. Kinetic analysis of currents partially blocked with 10 microM of each 293B enantiomer revealed that only 3R,4S-293B but not 3S,4R-293B exhibited a time-dependent block of I(Ks) and KCNQ1 currents, indicating preferential open channel block activity. 3. Inhibition of both KCNQ1 and I(Ks) channels by 3R,4S-293B but not by 3S,4R-293B increased during a 2 Hz train of stimuli. 4. At high extracellular potassium concentrations the inhibition of KCNQ1 by 3R,4S-293B and 3S,4R-293B was unaffected. Drug inhibition of KCNQ1 and I(Ks) by both enantiomers also did not display a significant voltage-dependence, indicating that 293B does not strongly interact with permeant ions in the pore. 5. The inhibitory properties of 3R,4S-293B on I(Ks)-channels but not those of 3S,4R-293B fulfill the theoretical requirements for a novel class III antiarrhythmic drug, i.e. positive use-dependency. This enantiomer therefore represents a valuable pharmacological tool to evaluate the therapeutic efficiency of I(Ks)blockade.

Synthesis and activity of novel and selective I(Ks)-channel blockers

Since the discovery of the I(Ks)-potassium channel as the slowly activating component of the delayed rectifier current (I(k)) in cardiac tissue, the search for blockers of this current has been intense. During the screening of K(ATP)-channel openers of the chromanol type we found that chromanol 293B was able to block I(Ks). Chromanol 293B is a sulfonamide analogue of the K(ATP)-channel openers but had no activity on this target. Experiments were initiated to improve the activity and properties based on this lead compound. As a screening model we used Xenopus oocytes injected with human minK (KCNE1). Variations of the aromatic substituent and the sulfonamide group were prepared, and their activity was evaluated. We found that the greatest influence on activity was found in the aromatic substituents. The most active compounds were alkoxy substituted. We chose HMR1556 ((3R, 4S)-(+)-N-[-3-hydroxy-2,2-dimethyl-6-(4,4,4-trifluorobutoxy)chroman-4-yl]-N-methyl-ethanesulfonamide) 10a for development as an antiarrhythmic drug. The absolute configuration, resulting from an X-ray single-crystal structure analysis, was determined.

Comparison of cloned Kir2 channels with native inward rectifier K+ channels from guinea-pig cardiomyocytes

The aim of the study was to compare the properties of cloned Kir2 channels with the properties of native rectifier channels in guinea-pig (gp) cardiac muscle. The cDNAs of gpKir2.1, gpKir2.2, gpKir2.3 and gpKir2.4 were obtained by screening a cDNA library from guinea-pig cardiac ventricle. A partial genomic structure of all gpKir2 genes was deduced by comparison of the cDNAs with the nucleotide sequences derived from a guinea-pig genomic library. The cell-specific expression of Kir2 channel subunits was studied in isolated cardiomyocytes using a multi-cell RT-PCR approach. It was found that gpKir2.1, gpKir2.2 and gpKir2.3, but not gpKir2.4, are expressed in cardiomyocytes. Immunocytochemical analysis with polyclonal antibodies showed that expression of Kir2.4 is restricted to neuronal cells in the heart. After transfection in human embryonic kidney cells (HEK293) the mean single-channel conductance with symmetrical K+ was found to be 30.6 pS for gpKir2.1, 40.0 pS for gpKir2.2 and 14.2 pS for Kir2.3. Cell-attached measurements in isolated guinea-pig cardiomyocytes (n = 351) revealed three populations of inwardly rectifying K+ channels with mean conductances of 34.0, 23.8 and 10.7 pS. Expression of the gpKir2 subunits in Xenopus oocytes showed inwardly rectifying currents. The Ba2+ concentrations required for half-maximum block at -100 mV were 3.24 M for gpKir2.1, 0.51 M for gpKir2.2, 10.26 M for gpKir2.3 and 235 M for gpKir2.4. Ba2+ block of inward rectifier channels of cardiomyocytes was studied in cell-attached recordings. The concentration and voltage dependence of Ba2+ block of the large-conductance inward rectifier channels was virtually identical to that of gpKir2.2 expressed in Xenopus oocytes. Our results suggest that the large-conductance inward rectifier channels found in guinea-pig cardiomyocytes (34.0 pS) correspond to gpKir2.2. The intermediate-conductance (23.8 pS) and low-conductance (10.7 pS) channels described here may correspond to gpKir2.1 and gpKir2.3, respectively.

Characterization of TASK-4, a novel member of the pH-sensitive, two-pore domain potassium channel family

We report the primary sequence of TASK-4, a novel member of the acid-sensitive subfamily of tandem pore K(+) channels. TASK-4 transcripts are widely expressed in humans, with highest levels in liver, lung, pancreas, placenta, aorta and heart. In Xenopus oocytes TASK-4 generated K(+) currents displaying a marked outward rectification which was lost by elevation of extracellular K(+). TASK-4 currents were efficiently blocked by barium (83% inhibition at 2 mM), only weakly inhibited by 1 mM concentrations of quinine, bupivacaine and lidocaine, but not blocked by tetraethylammonium, 4-aminopyridine and Cs(+). TASK-4 was sensitive to extracellular pH, but in contrast to other TASK channels, pH sensitivity was shifted to more alkaline pH. Thus, TASK-4 in concert with other TASK channels might regulate cellular membrane potential over a wide range of extracellular pH.

Inhibition of IKs channels by HMR 1556

Chromanol HMR 1556 [(3R,4S)-(+)-N-[3-hydroxy-2,2-dimethyl-6-(4,4,4-trifluorobutoxy)chroman-4-yl]-N-methylmethanesulfonamide], a novel inhibitor of the slow component of the delayed outward current in heart muscle cells (IKs), has been characterized in several in-vitro systems. mRNA encoding for the human protein minK was injected into Xenopus oocytes, leading to the expression of IKs channels. HMR 1556 inhibited this current half-maximally at a concentration of 120 nmol/l (IC50). Expression of the K+ channels Herg, Kv 1.5, Kv 1.3 and Kir2.1, and also the cationic current HCN2, were blocked little or not at all by 10 micromol/l HMR 1556. In isolated ventricular myocytes from the guinea pig the whole-cell patch-clamp method revealed inhibition of the IKs current with an IC50, of 34 nmol/l. Other current components, like IKr and IK1. were only slightly blocked at an HMR 1556 concentration of 10 micromol/l, whereas 10 micromol/l HMR 1556 inhibited the transient outward current I(to) and the sustained outward current I(sus) in rat ventricular myocytes by 25% and 36%, respectively. The L-type Ca2+ channel in guinea pig cardiomyocytes was blocked by 10 micromol/l HMR 1556 by 31%. Guinea pig right papillary muscles were investigated by the micropuncture technique at various pacing rates. In the frequency range of 0.5-7 Hz HMR 1556 (1 micromol/l) caused a prolongation of the action potential duration at 90% repolarization (APD90) by 19%-27%. In the presence of isoproterenol (10 micromol/l) the prolongation of the APD90 was more pronounced at low pacing rates (47% at 0.5 Hz and 35% at 1 Hz, compared with 25% at 7 Hz). The monophasic action potential was recorded in Langendorff-perfused guinea pig hearts. In spontaneously beating preparations, HMR 1556, at 0.1 micromol/l and 1 micromol/l, prolonged the MAPD90 by 3% and 10%, respectively, with no further prolongation at 10 micromol/l. The prolongation was much greater at low pacing rates [25% at 100 beats per min (bpm) and 13% at 150 bpm] than at fast pacing rates (9% at 350 bpm). The left ventricular pressure LVPmax was not affected at 1 micromol/l HMR 1556, but it decreased by 15% at 10 micromol/l. Other parameters, like the heart rate and coronary flow, were only slightly decreased at 1 micromol/l HMR 1556. In conclusion, HMR 1556 is a potent and selective inhibitor of the IKs current in guinea pig ventricular myocytes. The prolongation of the action potential duration is maintained at fast pacing rates.

Oncogenic potential of EAG K(+) channels

We have investigated the possible implication of the cell cycle-regulated K(+) channel ether à go-go (EAG) in cell proliferation and transformation. We show that transfection of EAG into mammalian cells confers a transformed phenotype. In addition, human EAG mRNA is detected in several somatic cancer cell lines, despite being preferentially expressed in brain among normal tissues. Inhibition of EAG expression in several of these cancer cell lines causes a significant reduction of cell proliferation. Moreover, the expression of EAG favours tumour progression when transfected cells are injected into immune-depressed mice. These data provide evidence for the oncogenic potential of EAG.

[Abstract or concrete: the importance of biotechnological descriptions in its evaluation]

Biotechnology is an environmental issue that can be evaluated with regard to the impact of the technology "as such" or with regard to specific products. We assume that the concreteness of presentations of biotechnology has an influence on evaluations of risks and benefits. We conducted two experimental studies. In Study 1, 99 subjects evaluated the strength and importance of pro and contra arguments that were presented in short texts on biotechnology. In study 2, 141 subjects were given short texts on biotechnology as well as 15 scales measuring evaluations of risks and chances. Datareveal an influence of the factor "concreteness" on evaluations of pro arguments and benefits as well as on evaluations of contra arguments and risks. But results point to an interaction between levels of concreteness of descriptions and their specific contents: in the pharmaceutical domain concrete descriptions are evaluated more positively than abstract descriptions, in the agricultural domain concrete descriptions are evaluated more negatively.

Cell cycle-related changes in the conducting properties of r-eag K+ channels

Release from arrest in G2 phase of the cell cycle causes profound changes in rat ether-à-go-go (r-eag) K+ channels heterologously expressed in Xenopus oocytes. The most evident consequence of the onset of maturation is the appearance of rectification in the r-eag current. The trigger for these changes is located downstream of the activation of mitosis-promoting factor (MPF). We demonstrate here that the rectification is due to a voltage-dependent block by intracellular Na+ ions. Manipulation of the intracellular Na+ concentration indicates that the site of Na+ block is located approximately 45% into the electrical distance of the pore and is only present in oocytes undergoing maturation. Since the currents through excised patches from immature oocytes exhibited a fast rundown, we studied CHO-K1 cells permanently transfected with r-eag. These cells displayed currents with a variable degree of block by Na+ and variable permeability to Cs+. Partial synchronization of the cultures in G0/G1 or M phases of the cell cycle greatly reduced the variability. The combined data obtained from mammalian cells and oocytes strongly suggest that the permeability properties of r-eag K+ channels are modulated during cell cycle-related processes.

Mitosis-promoting factor-mediated suppression of a cloned delayed rectifier potassium channel expressed in Xenopus oocytes

The cell cycle is the crucial process that leads to mitosis in all cell types. The dramatic redirectioning of many cellular processes during the cycle is known to involve ion channels, either changing their level of expression or their voltage dependence, as in the case of inward rectifiers. Here we describe the specific inhibition of heterologously expressed ionic channels at the onset of maturation in Xenopus oocytes. In cells expressing rat eag (R-eag) potassium channels, maturation induces a dramatic reduction in the current amplitude, which is almost complete in most cases. The key molecule in oocyte maturation, the mitosis-promoting factor (a complex of cyclin B and p34cdc2), is able to induce similar changes when injected into the oocytes.

Functional expression of a rat homologue of the voltage gated either á go-go potassium channel reveals differences in selectivity and activation kinetics between the Drosophila channel and its mammalian counterpart

We have cloned a mammalian (rat) homologue of Drosophila ether á go-go (eag) cDNA, which encodes a distinct type of voltage activated potassium (K) channel. The derived Drosophila and rat eag polypeptides share > 670 amino acids, with a sequence identity of 61%, exhibiting a high degree of similarity at the N-terminus, the hydrophobic core including the pore forming P region and a potential cyclic nucleotide binding site. Rat eag mRNA is specifically expressed in the central nervous system. In the Xenopus oocyte expression system rat eag mRNA gives rise to voltage activated K channels which have distinct properties in comparison with Drosophila eag channels and other voltage activated K channels. Thus, the rat eag channel further extends the known diversity of K channels. Most notably, the kinetics of rat eag channel activation depend strongly on holding membrane potential. Hyperpolarization slows down the kinetics of activation; conversely depolarization accelerates the kinetics of activation. This novel K channel property may have important implications in neural signal transduction allowing neurons to tune their repolarizing properties in response to membrane hyperpolarization.

Ether-à-go-go encodes a voltage-gated channel permeable to K+ and Ca2+ and modulated by cAMP

The Drosophila ether-à-go-go (eag) mutant is responsible for altered potassium currents in excitable tissue. These mutants exhibit spontaneous, repetitive firing of action potentials in the motor axons of larval neuromuscular junctions. The eag gene encodes a polypeptide that shares sequence similarities with several different ionic channel proteins, including voltage-gated potassium channels, an inward rectifier as well as cyclic-nucleotide-gated channels. These formal similarities in the derived primary sequences indicate that eag polypeptides might express a new type of ion channel. Here we report the expression by eag RNA in Xenopus oocytes of such a channel which incorporates properties of both voltage- and ligand-gated channels. The permeability of these eag channels to potassium and calcium is dependent on voltage and cyclic AMP. The ability to mediate potassium-outward and calcium-inward currents endows this channel with properties likely to be important in the modulation of synaptic efficiency in both central and peripheral nervous systems.

[The value of digital luminescence radiography within the scope of traumatologic follow-up examinations]

At the present time we cannot unhesitatingly recommend the general use of digital luminescence radiography in traumatological follow-up examinations. Marked drawbacks of this method are, for example, sudden changes in contrast in the marginal areas of osteosynthesis material, occasional limitations in the detailed assessment of spongious structures and problems in respect of imaging geometry. By modifying the image processing parameters, increasing the image matrix and enlarging the format spectrum, however, these problems should be capable of being resolved in the future. Positive features, on the other hand, are even now the possibility of reducing the dosage to a marked degree in many traumatological follow-up examinations, especially in children and adolescents, and in case of conservatively treated fractures. In the long run we can foresee the routine use of digitalised examination methods on traumatology coupled with the possibility of storage in an image filing and communication system, although this is at present not yet feasible due to lack of requisite experience and the cost of the necessary equipment.

Sonographical findings in Whipple's disease. A case report with regard to the literature

We present a case report of a 60-year-old male patient and subsequently discuss sonographical findings in Whipple's disease. This particular patient showed an intraabdominal tumorous mass. Symptoms of a malabsorption disorder were absent. Computer-assisted tomography and radiological examination could not determine the origin of the tumor. Sonography demonstrated a polycyclic hyperechoic mass in the root of the mesentery. The small intestine was not distended and showed normal peristalsis. Its wall was hyperechoic concentrically thickened. Final diagnosis was established from a diagnostic laparotomy showing enlarged lymph nodes and distended lymphatic vessels. Based on the literature the described sonographical findings seem to be typical in cases of Whipple's disease.

Real-time sonography of the mediastinum in adults: a study in 100 healthy volunteers

Real-time sonography has proved to be a valuable tool in the evaluation of the mediastinum in children. In the literature there is a paucity of information on ultrasound examination of the mediastinum in adults. Using a 3.5-MHz sector scanner, we evaluated a new method for the examination of mediastinal organs in adults, which is practicable in routine as well as emergency diagnosis. The endpoints of this study were the visibility of mediastinal organs and the discomfort of the patient. In 100 healthy volunteers aged 20-40 years, the normal anatomy of the anterior and middle mediastinum was investigated. Neither the height nor the weight of the volunteers limited the examination. We found that this method causes no discomfort to the subject. Via the supra-, infra- and left parasternal approaches, anatomical structures of the mediastinum are visible in a high percentage of cases. To date, this method has proved its practicability in more than 250 patients suffering from blunt thoracic trauma, primary and metastatic tumours, and infections of the mediastinum.

Influence of bone and soft-tissue operations on serum concentrations of growth hormone, somatomedin C and alkaline phosphatase

After animal experiments suggested there was an interaction between growth hormone and bone healing, our aim in this paper was to ascertain whether there were any changes or possible interaction between the serum level of growth hormone, somatomedin C and alkaline phosphatase while a fractured bone was healing. To this end, the serum concentrations of growth hormone, somatomedin C, alkaline phosphatase and calcium were ascertained both pre- and post-operatively in two groups of patients--one with bone operations, the other with soft-tissue operations--and the results were compared. Comparing the groups, we found that after bone operations there was no increase in the serum level of growth hormone, nor of somatomedin C. An increase would have implied that these two hormones are directly involved in bone regeneration. There was no change in the serum level of alkaline phosphatase or calcium after either bone or soft-tissue operations.

Prognostic relevance of ploidy, proliferation, and resistance-predictive tests in ovarian carcinoma

In a cooperative study specimens of 37 patients with stage III and IV ovarian carcinomas who had been treated with chemotherapy were investigated utilizing flow cytometry and an in vitro short-term test for predicting resistance. Patients with aneuploid tumors had significantly shorter survival rates than did those with diploid tumors. Patients whose tumors showed a low G0/G1 cell proportion or a high proliferation pool (S- and G2/M cell-proportion) seemed to die earlier. There was also a tendency for patients with in vitro resistant tumors to die earlier under chemotherapy than those with sensitive tumors.