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Biomedical subjects

W Urban

Publications and source records attributed to W Urban.

At least 19 recordsLinked to original sources
PubMed2003

Pulmonary 15NO uptake in man.

Nitric oxide (NO) is commonly thought to reveal more precise values of pulmonary gas uptake through alveolar-capillary membranes (DL) than the normally used carbon monoxide (CO). Since such measurements are influenced by a significant endogenous NO delivery within human airways, we propose the use of the naturally occurring (15)N-labelled stable nitric oxide isotope (15)NO. It occurs with a relative abundance of 0.37% of the dominating isotope (14)NO. Therefore, the endogenous (15)NO production can be neglected. In the present pilot study we demonstrate the workability of (15)NO in determining DL in healthy individuals. In seven female and 15 male volunteers, averaged values of DL increase with increasing mean alveolar volume as well as individual body height ( P=0.000001). Due to the very high significance level obtained from the multiple regression analysis, we conclude that the application of (15)NO establishes a novel approach to calculate standard values of DL. Such calculations can be employed to predict a reference for patients who suffer from pulmonary diffusion limitation.

Adolescent↗
PubMed2001

Spectroscopic detection of biological NO with a quantum cascade laser.

Two configurations of a continuous wave quantum cascade distributed feedback laser-based gas sensor for the detection of NO at a parts per billion (ppb) concentration level, typical of biomedical applications, have been investigated. The laser was operated at liquid nitrogen temperature near lambda = 5.2 microns. In the first configuration, a 100 m optical path length multi-pass cell was employed to enhance the NO absorption. In the second configuration, a technique based on cavity-enhanced spectroscopy (CES) was utilized, with an effective path length of 670 m. Both sensors enabled simultaneous analysis of NO and CO2 concentrations in exhaled air. The minimum detectable NO concentration was found to be 3 ppb with a multi-pass cell and 16 ppb when using CES. The two techniques are compared, and potential future developments are discussed.

Breath Tests↗
PubMed2000

More Sub-Doppler Heterodyne Frequency Measurements on OCS between 56 and 63 THz.

By using tunable microwave sidebands added to CO-laser lines, we have made more sub-Doppler heterodyne frequency measurements on OCS. Three new rotational transitions have been measured for each of three absorption bands, 10(0)0-00(0)0, 02(0)1-00(0)0, and 03(1)1-01(1)0. The absolute uncertainties of the measurements are on the order of +/-25 kHz. New calibration tables are given for the region 1860-1925 and 2020-2085 cm(-1) based on the most recent OCS measurements. Copyright 2000 Academic Press.

Journal Article↗
PubMed1999

An anatomic evaluation of T-Fix suture device placement for arthroscopic all-inside meniscal repair.

This investigation documented the locations of endoscopically applied T-Fix suture devices (Acufex Microsurgical, Mansfield, MA) placed in six fresh-frozen cadaveric knees (age, 60 to 72 years) in relationship to the joint capsule, and adjacent neurovascular and musculotendinous structures. Five T-Fix devices were placed in the posterior meniscal regions at approximately 20 degree intervals. Gross dissection enabled T-Fix bar and suture placement identification. Fifty total devices were placed (23 medially and 27 laterally). Lateral: None of the devices penetrated more superficially than the deepest capsular layer (layer III). Six of the 27 devices placed at the posterior horn of the lateral meniscus pierced the popliteus tendon. None of the bars pierced the lateral collateral ligament (layer III). All devices placed at the posterolateral knee were outside the arcuate ligament (layer III) but inside the fabellofibular ligament (layer II). Medial: Seven of the 23 devices pierced the deep medial collateral ligament (MCL, layer III), and 4 pierced the superficial MCL (layer II). Three devices pierced the sartorius tendon (layer I) and one pierced the gracilis tendon (layer II). None of the medial devices created a plicating effect on the posterior capsule. None of the devices were placed near neurovascular structures. Devices placed within the posterior meniscal horns had a > or =1.5-cm buffer zone from the popliteal neurovascular bundle. Most bars (36 of 50) were anchored to the capsular layer (layer III) after piercing the meniscocapsular junction (layer II). T-Fix devices simulating arthroscopic all-inside meniscal repair provided well-positioned, solid suture anchorage through the junction with no neurovascular involvement. Care needs to be taken when placing lateral (popliteus muscle) and medial (gracilis, sartorius tendons and superficial MCL) devices to avoid possible soft tissue tenodesis.

Aged↗
PubMed1999

LMR spectroscopy: a new sensitive method for on-line recording of nitric oxide in breath.

Laser magnetic resonance spectroscopy (LMRS) is a sensitive and isotope-selective technique for determining low concentrations of gaseous free radicals with high time resolution. We used this technique to analyze the nitric oxide (NO) concentration profile while simultaneously measuring the flow and expired volume during several single breathing cycles. Eight healthy, nonallergic volunteers were investigated. An initial NO peak was found in all breathing cycles before the NO concentration dropped to a relatively stable plateau in the late phase of expiration. The nasal NO peak was significantly higher than the oral NO peak. The nasal NO plateau was always higher than the oral NO plateau. The height of the initial nasal and oral NO peak rose with increasing duration of breath hold, whereas the late expiratory NO plateau changed only little for either the nasal or the oral breathing cycles. Our findings demonstrate, in line with other reports using other techniques, that the nose is the primary source for NO within the airways.

Adult↗
PubMed1999

[Amazing career of Cracovian physician in the 15th century].

The epoque of king Casimir Jagiellonczyk was a period of splendid development of the Polish-Lithuanian state, mainly due to regaining of Danzig (Gdansk). In the time, Godzislaw from Gorzyce, village of undetermined location (there were 13 villages named Gorzyce in Poland), son of a poor Polish peasant, made a career. He was born about 1410 and in 1428 entered the Cracow University, the only in the country at that time. Nobody knows where (probably in Italy) and for whose money he got university degrees, including doctor degree of medicine. In the forties of 15th century he was such a famous physician in Cracow, that the patients came to him even from Great Poland. Godzislaw was enobled by king Casimir in 1456, when he already was a king's physician and a priest. He probably died in Cracow about 1470, twenty years before the king, who was some 15 years younger.

Famous Persons↗
PubMed1998

Faraday Laser Magnetic Resonance Spectroscopy of Vibrationally Excited C2D.

We studied the gas phase spectrum of the deuterated ethynyl radical C2D in the region between 3196 and 3243 cm-1 using a Faraday LMR spectrometer in combination with a CO overtone laser. The C2D radicals were generated in a dc glow discharge containing helium, deuterium, and acetylene. We observed a hot band between two vibronic 2Pi states with an origin at 3225 cm-1. The lower level is assigned to the first excited bending level of the electronic X ground state. The upper level corresponds to the first excited electronic state A at 3513 cm-1, which was observed previously [J. Mol. Struct. 190, 41-60 (1988)]. This region is subject to strong vibronic interaction, caused by mixing of the electronic X ground state with the A state at 3513 cm-1. From the analysis of the spectra we could determine the orbital g factor of the upper level, which gave important information about the mixing ratios. In addition we were able to derive a precise term value for the first excited bending level of the electronic X ground state. The experimentally derived molecular parameters are compared with theoretically calculated values, obtained by ab initio calculations. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Sub-Doppler Heterodyne Frequency Measurements on OCS Near 2900 cm-1 Using a CO Overtone Sideband Spectrometer.

We present sub-Doppler heterodyne frequency measurements on 10 rovibrational transitions of carbonyl sulfide (OCS) between 2894 and 2910 cm-1. The measurements were made using a CO overtone laser which had limited tuneability through the generation of microwave sidebands in a CdTe crystal. With this technique the laser frequencies were shifted to the desired OCS transition frequencies. The transition frequencies could be measured with uncertainties less than 30 kHz (Deltanu/nu = 3 x 10(-10)) by frequency offset-locking the CO overtone laser to combination frequencies of two saturation-stabilized CO2 laser standards. The measured transition frequencies of OCS were combined with previous sub-Doppler, Fourier transform, and microwave measurements to recalculate improved calibration tables for the 10(0)1-00(0)0, 11(1e)1-01(1e)0, and 11(1f)1-01(1f)0 bands. These tables are suitable for the calibration of infrared spectrometers in the 87 THz region (near 2900 cm-1). Copyright 1998 Academic Press.

Journal Article↗
PubMed1996

Identification of N2 as a metabolite of acetylhydrazine in the rat.

In the pathogenesis of isoniazid-induced hepatic injury, cytochrome P450-dependent metabolic activation of the metabolite, acetylhydrazine (AcHz), is the crucial step. Exhalation of [14C]-carbon dioxide has previously been used to quantify indirectly this pathway. In contrast, according to the current concept of AcHz bioactivation, molecular nitrogen is produced directly, but has not yet been identified. Here, we measured [15N]-nitrogen and 14CO2 exhalation, after the administration of [15N2]-[14C]-AcHz, in rats. Laser magnetic resonance (LMR) spectroscopy, a new sensitive and specific technique for the measurement of 15N and 14N in gas samples, was used. To demonstrate the involvement of cytochrome P450, rats were treated with phenobarbital (PB) or PB+cobalt(II) chloride (CoCl2) (n = 3 in each group). Time-dependent 15N2 exhalation differed significantly between treatment groups (p < 0.001). At 240 min, cumulative exhalation of 15N was 1.92 +/- 0.43% (mean +/- SE) of the dose in the control group, 2.53 +/- 0.23% in the PB group, and 1.00 +/- 0.15% in the PB+CoCl2 group (p < 0.05 compared to controls, p < 0.01 compared to PB). Cumulative exhalation of 14CO2 in 24 h ranged from 15.1 to 21.9%, with no significant difference between treatment groups. In conclusion, N2 is a metabolite of AcHz. N2 formation reflects the cytochrome P450-mediated activation of AcHz and can be used as an index of this pathway. Generally, LMR spectroscopy is valuable for monitoring any N2-liberating process in vivo.

Animals↗