XUV frequency comb production with an astigmatism-compensated enhancement cavity

We have developed an extreme ultraviolet (XUV) frequency comb for performing ultra-high precision spectroscopy on the many XUV transitions found in highly charged ions (HCI). Femtosecond pulses from a 100 MHz phase-stabilized near-infrared frequency comb are amplified and then fed into a femtosecond enhancement cavity (fsEC) inside an ultra-high vacuum chamber. The low-dispersion fsEC coherently superposes several hundred incident pulses and, with a single cylindrical optical element, fully compensates astigmatism at the w₀ = 15 µm waist cavity focus. With a gas jet installed there, intensities reaching ∼ 10¹⁴ W/cm² generate coherent high harmonics with a comb spectrum at 100 MHz rate. We couple out of the fsEC harmonics from the 7th up to the 35th (42 eV; 30 nm) to be used in upcoming experiments on HCI frequency metrology.

100 MHz frequency comb for low-intensity multi-photon studies: intra-cavity velocity-map imaging of xenon

We raise the power from a commercial 10 W frequency comb inside an enhancement cavity and perform multi-photon ionization of gas-phase atoms at 100 MHz for the first time, to the best of our knowledge. An intra-cavity velocity-map-imaging setup collects electron-energy spectra of xenon at rates several orders of magnitude higher than those of conventional laser systems. Consequently, we can use much lower intensities ${\sim}{{10}^{12}} \;{\rm W}/{{\rm cm}^2} $∼10¹²W/cm² without increasing acquisition times above just a few seconds. The high rate and coherence of the stabilized femtosecond pulses are known to be transferred to the actively stabilized cavity and will allow studying purely perturbative multi-photon effects, paving the road towards a new field of precision tests in nonlinear physics.

Incidences and predictors of difficult laryngoscopy in adult patients undergoing general anesthesia : a single-center analysis of 102,305 cases

BACKGROUND

Hypoxemia caused by difficulties in airway management presents a major cause for perioperative morbidity and mortality. The ability to predict difficult laryngoscopy more accurately would enable anesthesiologists to take specific precautions to reduce airway risks and prevent patient-threatening events.

METHODS

Over a 6-year period of time, all anesthesia records with a documented direct laryngoscopic view were retrieved from the electronic data management system and statistically processed. The Cormack-Lehane four-point scale of grading laryngoscopy was used to assess visibility of the vocal cords.

RESULTS

Of 102,306 cases, the overall rate of difficult laryngoscopy was 4.9 %. Male gender (6.5 %), Mallampati score III and IV (17.3 %), obesity with a BMI ≥35 kg/m(2) (6.1 %), as well as physical status ASA III or IV (6.2 %), were identified as risk factors for difficult laryngoscopy. Patients undergoing surgery in the departments of oromaxillofacial (8.9 %), ear nose throat surgery (ENT) (7.4 %), and cardiac surgery (7.0 %) showed the highest rates of difficult laryngoscopy.

CONCLUSIONS

The results indicate that the risk for difficult airway situations might substantially differ between surgical patient groups. In hospitals with departmental structures and spatially separated operating rooms, the deduction might be increased awareness and particular structural preparation for difficult airway situations in the respective subspecialties.

[Anesthesiological time requirements and reasons for delayed processes in MRI examinations of children undergoing sedation or general anesthesia]

PURPOSE

MRI examinations in children under sedation or general anesthesia are a multidisciplinary challenge for pediatric, radiology and anesthesiology departments. This article presents findings about patient population, anesthesiology procedures and process times in pediatric MRI procedures under sedation or general anesthesia. The analysis is focused on the potential to optimize process times.

MATERIALS AND METHODS

Retrospectively over a 5-year period, data from diagnostic radiology procedures in children requiring sedation or general anesthesia were retrieved from anesthesia records and analyzed statistically.

RESULTS

The median anesthesia time in patients without an airway device was 6 min. In patients with a laryngeal mask (19 min) and in patients receiving endotracheal intubation (20 min), the anesthesia time was significantly longer (p < 0.001). The need for airway management in the age groups was 67 % for neonates, 25 % for infants, 8 % for toddlers and 7 % for school children. Improved clinical pathways could potentially save additional time up to 69 hours in our period of investigation.

CONCLUSION

In relation to older children, toddlers, infants and neonates had the longest process times in diagnostic radiology procedures, caused by the need to secure the airway. Improved pre-MRI processes have an enormous potential to generate additional examination time.

[Measurement of retinal thickness with the Heidelberg retina tomograph for patients with macular edema and healthy individuals]

BACKGROUND

This study was carried out to test the reliability of a defined cut-off value for retinal thickness with estimation of the sensitivity, specificity and formation of an edema index in comparison to retinal thickness.

MATERIALS AND METHODS

This was a single center prospective clinical non-blinded study of 100 eyes, including 22 eyes with central vein or branch vein occlusions, 20 eyes with diabetic macular edema, 6 eyes with postoperative macular edema, 2 eyes with uveitis and 50 healthy eyes. Detection of macular edema was carried out by third generation optical coherence tomography. Using the latest version of the Heidelberg retina tomograph (HRT 3) series of five images were produced and evaluated. The 9-zone circle of the HRT was used as the analysis contour.

RESULTS

The reliability of measuring retinal thickness with the HRT in the subjects showed an intraclass correlation between 0.248 and 0.740 and patients with macular edema showed values between 0.515 and 0.949. The reliability of the edema index with the HRT in the subjects showed an intraclass correlation between 0.461 and 0.826 and patients with macular edema showed values between 0.383 and 0.826. The calculated cut-off values were between 285 µm and 360 µm. The corresponding sensitivity values were between 74.7% and 95.9% with a corresponding specificity of 74.7-90.2%. There was also a highly significant correlation between the edema index and retinal thickness (p < 0.001).

CONCLUSIONS

The retina module of the latest generation HRT is capable of reproducible measurement of the retinal thickness in micrometers. The defined cut-off values correspond to expectations and can be used in this form in the clinical practice.

[Diode laser. Ex vivo studies on vaporization and coagulation characteristics]

INTRODUCTION AND OBJECTIVES

Laser therapy of symptomatic benign prostatic hyperplasia (BPH) remains a challenge for most urologic surgeons. The main goal of laser surgery is to achieve a marked volume reduction and to decrease bladder outlet obstruction and lower urinary tract symptoms with minimal morbidity. Laser therapy encompasses a variety of techniques using different laser wavelengths, application systems, and surgical techniques to achieve contrasting tissue effects. In an in vitro animal model we compared the vaporization and coagulation effects of the potassium-titanyl-phosphate (KTP) laser, holmium:yttrium-aluminum-garnet (Ho:YAG) laser, and diode laser (980 nm).

MATERIAL AND METHODS

In an in vitro model using isolated perfused porcine kidneys we investigated the vaporization, the coagulation effect, and the bleeding rate of the KTP, Ho:YAG, and diode lasers on five porcine kidneys each. The application of each laser type was standardized. The area of laser application was 1 cm x 1 cm. The KTP group received an application with 80 W, the Ho:YAG group an application with 10-30 W, and the diode group an application with 30, 60, and 100 W. Hemostasis was measured semiquantitatively. Ablation and coagulation were investigated macro- and microscopically.

RESULTS

Concerning the ablation capacity, the diode laser is most effective (more than fivefold) compared to the KTP and Ho:YAG lasers but demonstrated a rather large coagulation zone of up to tenfold in comparison to the KTP and Ho:YAG lasers. Semiquantitatively, in terms of bleeding rate, all lasers were equivalent in this ex vivo model.

CONCLUSIONS

Our very early and limited experience indicates that KTP (80 W) and Ho:YAG (30 W) laser application are equivalent in terms of tissue ablation capacity and coagulation in an experimental setting. The diode laser at 980 nm is superior in terms of ablation capacity but has a large coagulation zone. Concerning the bleeding rate all tested lasers are equivalent in this ex vivo model.

[VC and DCE in groundwater and drainage channel water]

In an area used merely for gardening in a downland moor, which is partly transformed to an industrial estate, accidentally a contamination of a drainage channel with VOC's - predominantly chloroethylene (vinyl chloride [VC]) and 1.2-cis-dichloroethylene (DCE) - was found. The ascending ground water leaks into the drainage channels. The dissolved harmful substances (water solubility of VC is 1.6 g/l) can reach the radix range of plants and fruit bosks and can theoretically be incorporated with the water influx. Additionally the water from the drainage channels can be used to water the crops. Six gardens and a housing were involved. In the groundwater of the mainly concerned region max. 5,000 microg/l VOC's (quite predominantly VC and DCE) was measured from 147 samples. In the drainage channel water max. 2,500 microg/l was measured from 52 samples (limit value according to the drinking water ordinance is 10 microg/l). In the sediment of the channel with approximately 60,000 microg/kg VOC was found in dry matter (6 samples). We describe, how the consumer protection dept. dealt with this unexpected situation and what measures were taken. The impact on human health by the contaminated ground and channel water or by means of contaminated plants are determined for tree fruits, potatoes, bulbs and carrots. The soil air was contaminated, but in buildings no harmful compounds were detectioned.

Isolation, identification and changes in the composition of lactic acid bacteria during the malting of two different barley cultivars

Malt has a complex microbial population, which changes as the malting process commences. Little is known about the proliferation of lactic acid bacteria (LAB) in each of the malting phases. In this study, we determined the number of LAB present in the different phases of malting with Clipper and Prisma barley cultivars. The strains were identified to species level by using numerical analysis of total soluble cell protein patterns, RAPD-PCR banding patterns and 16S rRNA sequencing. The number of viable LAB in the barley before steep was higher in Prisma than Clipper (7.6 x 10(4) and 1.2 x 10(3) cfu/g, respectively). Despite this, the number of viable cells recorded in the first steep water was slightly higher for Clipper (9.0 x 10(5) cfu/g) than Prisma (5.5 x 10(5) cfu/g). More or less, the same cell numbers were recorded for the two barley cultivars after the first and second dry stands. Both cultivars displayed more or less the same cell numbers (3.7 x 10(7) for Clipper and 3.2 x 10(7) cfu/g for Prisma) after the third day of germination. However, a higher number of LAB were detected in the kilned Prisma malt (6.9 x 10(4) cfu/g) than the Clipper malt (1.5 x 10(4) cfu/g). Leuconostoc argentinum, Le. lactis and Weissella confusa were the most predominant in both cultivars. A few strains were identified as W. paramesenteroides (four strains), Lactobacillus casei (five strains), Lactococcus lactis (five strains) and Lb. rhamnosus (two strains). Lb. casei and Lb. rhamnosus were not isolated from the Prisma cultivar, while W. paramesenteroides and Lc. lactis were absent in the Clipper cultivar. Kilned malt of the Clipper cultivar contained predominantly Le. argentinum, whereas the Prisma cultivar contained mainly Lc. lactis. To our knowledge. this is the first report of LAB in Clipper and Prisma barley and the various malting phases. The influence of the various groups of lactic acid bacteria on the fermenting ability of brewers' yeast is currently being determined.

Mapping and expression pattern analysis of key components of the major histocompatibility complex class I antigen processing and presentation pathway in a representative human renal cell carcinoma cell line

Renal cell carcinoma (RCC) represent approximately 5% of all cancer deaths. At the time of presentation, over 50% of the patients have already developed locally advanced or metastatic disease with five-year survival rates of less than 20%. Although relative resistant to conventional regimens, RCC are partially susceptible to T cell-based immunotherapy. To further develop this treatment modality, two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was applied for both the mapping of the key components of the major histocompatibility complex (MHC) class I antigen processing and presentation machinery (APM) and the characterization of the constitutive and cytokine-regulated protein expression profiles in a representative human RCC cell line. The latter aspect is based on the fact, that the expression level of some of the APM components can be altered in response to interferon (IFN)-gamma treatment. Total cell lysates from untreated and IFN-gamma-treated tumor cells were separated on 2-D PAGE gels using broad range immobilized pH gradient (IPG) strips. Serial Western blot analyses using sets of APM-specific antibodies were performed to target the relevant protein spots. Protein verification was mostly accomplished via peptide mass finger-printing using matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). To date, the majority of the APM-related components have been identified and mapped. In addition, the different protein expression profiles of untreated and IFN-gamma-treated RCC cells are under investigation.

Modulation of angiotensin-converting enzyme by nitric oxide

1. The aim of the present study was to determine the effect of nitric oxide (NO) on angiotensin-converting enzyme (ACE) activity. 2. A biochemical study was performed in order to analyse the effect of the NO-donors, SIN-1 and diethylamine/NO (DEA/NO), and of an aqueous solution of nitric oxide on the ACE activity in plasma from 3-month old male Sprague-Dawley rats and on ACE purified from rabbit lung. SIN-1 significantly inhibited the activity of both enzymes in a concentration-dependent way between 1 and 100 microM. DEA/NO inhibited the activity of purified ACE from 0.1 microM to 10 microM and plasma ACE, with a lower potency, between 1 and 100 microM. An aqueous solution of NO (100 and 150 microM) also inhibited significantly the activity of both enzymes. Lineweaver-Burk plots indicated an apparent competitive inhibition of Hip-His-Leu hydrolysis by NO-donors. 3. Modulation of ACE activity by NO was also assessed in the rat carotid artery by comparing contractions elicited by angiotensin I (AI) and AII. Concentration-response curves to both peptides were performed in arteries with endothelium in the presence of the guanylyl cyclase inhibitor, ODQ (10 microM), and the inhibitor of NO formation, L-NAME (0.1 mM). NO, which is still released from endothelium in the presence of 10 microM ODQ, elicited a significant inhibition of AI contractions at low concentrations (1 and 5 nM). In the absence of endothelium, 1 microM SIN-1 plus 10 microM ODQ, as well as 10 microM DEA/NO plus 10 microM ODQ induced a significant inhibition on AI-induced contractions at 1 and 5 nM and at 1-100 nM, respectively. 4. In conclusion, we demonstrated that (i) NO and NO-releasing compounds inhibit ACE activity in a concentration-dependent and competitive way and that (ii) NO release from endothelium physiologically reduces conversion of AI to AII.

Amiloride-sensitive sodium channels in confluent M-1 mouse cortical collecting duct cells

Confluent M-1 cells show electrogenic Na+ absorption and possess an amiloride-sensitive Na(+)-conductance (Korbmacher et al., J. Gen. Physiol. 102:761-793, 1993). In the present study, we further characterized this conductance and identified the underlying single channels using conventional patch clamp technique. Moreover, we isolated poly(A)+ RNA from M-1 cells to express the channels in Xenopus laevis oocytes, and to check for the presence of transcripts related to the epithelial Na+ channel recently cloned from rat colon (Canessa et al., Nature 361:467-470, 1993). Patch clamp experiments were performed in 6-13-day-old confluent M-1 cells at 37 degrees C. In whole-cell experiments application of 10(-5) M amiloride caused a hyperpolarization of 24.9, SEM +/- 2.2 mV (n = 35) and a reduction of the inward current by 107 +/- 10 pA (n = 51) at a holding potential of -60 mV. Complete removal of bath Na+ had similar effects, indicating that the amiloride-sensitive component of the inward current is a Na+ current. The effect of amiloride was concentration-dependent with half-inhibition at 0.22 microM. The Na+ current saturated with increasing extracellular Na+ concentrations with an apparent Km of 24 mM. Na+ replacement for Li+ demonstrated a higher apical membrane conductance for Li+ than for Na+. In excised inside-out (i/o) or outside-out (o/o) patches from the apical membrane, we observed single-channels which showed slow kinetics and were reversibly inhibited by amiloride. Their average conductance for Na+ was 6.8 +/- 0.5 pS (n = 15) and for Li+ 11.2 +/- 1.0 pS (n = 14). They had no measurable conductance for K+. In o/o patches, channel activity was slightly voltage dependent with an open probability (NPo) of 0.46 +/- 0.14 and 0.16 +/- 0.05 at a holding potential of -100 and 0 mV, respectively (n = 8, P < 0.05). Using the two-microelectrode voltage-clamp technique, we assayed defolliculated stage V-VI Xenopus oocytes for an amiloride-sensitive inward current 1-6 days after injection with H2O or with 20-50 ng of M-1 poly(A)+ RNA. In poly(A)+ RNA-injected oocytes held at -60 or -100 mV application of amiloride (2 microM) reduced the Na-inward current by 25.5 +/- 4.6 nA (n = 25) while it had no effect in H2O-injected oocytes (n = 19). Northern blot analysis of M-1 poly(A+) RNA revealed the presence of transcripts related to the three known subunits of the rat colon Na+ channel (Canessa et al., Nature 367:463-467, 1994). We conclude that the channel in M-1 cells is closely related to the amiloride-sensitive epithelial Na+ channel in the rat colon and that the M-1 cell line provides a useful tool to investigate the biophysical and molecular properties of the corresponding channel in the cortical collecting duct.

minibrain: a new protein kinase family involved in postembryonic neurogenesis in Drosophila

The development of the adult central nervous system of Drosophila requires a precise and reproducible pattern of neuroblast proliferation during postembryonic neurogenesis. We show here that mutations in the minibrain (mnb) gene cause an abnormal spacing of neuroblasts in the outer proliferation center (opc) of larval brain, with the implication that mnb opc neuroblasts produce less neuronal progeny than do wild type. As a consequence, the adult mnb brain exhibits a specific and marked size reduction of the optic lobes and central brain hemispheres. The insufficient number of distinct neurons in mnb brains is correlated with specific abnormalities in visual and olfactory behavior. The mnb gene encodes a novel, cell type-specific serine-threonine protein kinase family that is expressed and required in distinct neuroblast proliferation centers during postembryonic neurogenesis. The mnb kinases share extensive sequence similarities with kinases involved in the regulation of cell division.

Epidemiologically closely related viruses from hemophilia B patients display high homology in two hypervariable regions of the HIV-1 env gene

The diversity of human immunodeficiency virus type 1 (HIV-1) is mainly caused by mutations that affect the gene encoding the gp120 envelope protein. Isolates differ to a large extent in the hypervariable regions of gp120. This study was undertaken to determine the degree of variation of HIV-1 env genes isolated from seven individuals with hemophilia B who became infected in association with administration of a suspected clotting factor lot. Two hypervariable regions and part of a constant region from proviral DNA of the peripheral blood leukocytes of these patients were amplified and the products of the polymerase chain reactions were sequenced. The sequences derived from five of the individuals displayed 100% sequence homology, 1 had two and 1 had six deviations from the consensus sequence. The alignment of the amino acid sequence so deduced revealed no comparable homology to any of these two hypervariable regions from a number of published isolates. The genetic variability of HIV-1 seems to be limited, at least in the early phase of infection, allowing the determination of close relationships between epidemiologically related strains.

Comparison of different methods for detecting human immune deficiency virus in human immunodeficiency virus-seropositive hemophiliacs

Since the detection of antibodies against the human immune deficiency virus (HIV) does not definitely prove HIV infection in hemophiliacs, virus detection was attempted by virus isolation from the peripheral blood monocytes (PBL), by demonstration of p24 antigen and decline of p24 antibody, and by detection of viral DNA by the polymerase chain reaction (PCR). Virus isolation was optimized by immediate coculture of PBL and by replacement of the reverse transcriptase test by the p24 antigen test, whereas the elimination of CD8+ lymphocytes proved to be unnecessary. Virus detection was dependent on the clinical stage of the illness. Virus isolation in 70 of 211 patients (33%) was more sensitive than detection of p24 antigen or decline of p24 antibody. PCR was performed in 25 patients and indicated infection in all of 15 isolation-positive cases and in 6 of 10 patients from whom virus was not isolated. Changes from negative to positive virus culture and from a weakly fusiogenic to a highly fusiogenic isolate were often accompanied by a progression of the disease. The results suggest that reactivation of HIV occurs when immune deficiency has become manifest. Apparently virus isolation detects only the virus already reactivated in vivo, whereas the PCR may also detect latent virus.

Structure of the voltage-dependent potassium channel is highly conserved from Drosophila to vertebrate central nervous systems

Voltage-sensitive potassium channels are found in vertebrate and invertebrate central nervous systems. We have isolated a rat brain cDNA by cross-hybridization with a probe of the Drosophila Shaker gene complex. Structural conservation of domains of the deduced protein indicate that the rat brain cDNA encodes a voltage-sensitive potassium channel. Of the deduced amino acid sequence, 82% is homologous to the Drosophila Shaker protein indicating that voltage-sensitive potassium channels have been highly conserved during evolution. Selective pressure was highest on sequences facing the intracellular side and on proposed transmembrane segments S4-S6, suggesting that these domains are crucial for voltage-dependent potassium channel function. The corresponding rat mRNA apparently belongs to a family of mRNA molecules which are preferentially expressed in the central nervous system.

Immunoglobulin biosynthesis in myeloma-associated and casein- and endotoxin-induced murine amyloidosis

Amyloidosis was induced in C57BL mice by daily injections of casein and in BALB/c mice by daily injections of endotoxin. There was no obvious disorder of immunoglobulin biosynthesis by spleen lymphocytes in these mice either before, during the development of, or in the amyloidotic stage. The pattern of immunoglobulin synthesis, assembly, and secretion was unaltered, the relative amount of heavy and light chains produced was normal, and there was an absence of immunoglobulin polypeptide chain fragments. Small amounts of amyloid were present in only 1 of 19 BALB/c and C3H mice (the IgG2a producing MOPC 173 tumor) bearing immunoglobulin-producing myeloma tumors and variants of these tumors. There was no relationship between excess light chain production by tumor plasma cells or spleen lymphocytes and the development of amyloidosis and there were no light chain fragments demonstrable. Antiserum prepared against casein-induced amyloid cross-reacted by immunofluorescence with the amyloid present in the MOPC 173 tumor-bearing mice, indicating the presence of common antigenic determinants in these two forms of amyloid. Attempts to study the biosynthesis of amyloid with incorporation of radioactively labeled amino acids were unsucessful.