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Biomedical subjects

S Klee

Publications and source records attributed to S Klee.

31 records · Page 2Linked to original sources
PubMed1996

The Ethylene Hot Band Spectrum near 3000 cm-1

A new hot band spectrum of ethylene has been recorded from 2970 to 3015 cm-1 at low rotational temperatures in a seeded molecular jet, using vibrational energy transfer from SF6 to C2H4. An IR-IR double resonance technique has been applied to pump the lower states and subsequently probe the hot bands. Two new hot bands, nu10 + nu11 - nu10 and nu7 + nu11 - nu7, have been found. The weak hot band starting from nu7 has been identified by direct labeling of some rotational levels in the nu7 manifold. High resolution FTIR spectra at ambient and at elevated temperatures have been recorded, too; it has thus become possible to extend the analysis to higher rotational quantum numbers. The previously analyzed nu9 + nu10 level has been reinvestigated and a b-type Coriolis interaction with the nearby nu7 + nu11 state has been observed. Rotational energy levels of nu7 + nu11 and of nu9 + nu10 have been fitted simultaneously, taking into account the local perturbations due to five dark states. From the shift of all K not equal 0 levels to higher frequencies in the nu10 + nu11 state, a global a-type Coriolis interaction with nu8 + 2nu12 has been identified.

Journal Article↗
PubMed1996

Infrared Transitions of H12C14N and H12C15N between 500 and 10 000 cm-1

We have measured the Fourier transform spectrum (FTS) of two isotopomers of hydrogen cyanide (H12C14N and H12C15N) from 500 to 10 000 cm-1. The infrared data have been combined with earlier published microwave and submillimeter-wave measurements. From this analysis new vibration-rotation energy levels and constants are given, based on the observation of a number of new vibrational levels, especially for H12C15N. The Coriolis interaction involving Deltav3 = -1, Deltav2 = 3, and Deltal = ±1 has been observed for a great many levels and in some cases the assignments of laser transitions allowed by this interaction are more clearly shown. New vibration-rotation constants are given that allow one to predict the transition wavenumbers for most of the transitions below 10 000 cm-1 with accuracies of about 0.5 cm-1 or better. Values are given for the power series expansion of the l-type resonance constants and for the centrifugal distortion constants, as well as the usual vibrational and rotational constants.

Journal Article↗
PubMed1996

The Rotational Spectrum of H2Te

In the present work, we study the spectrum of the H2Te molecule in the submillimeter-wave and far infrared region. An important aim of this investigation is the further experimental characterization of the anomalous "four-fold cluster effect" exhibited by the rotational energy levels in the vibrational ground state of H2Te. The spectrum in the region 90-472 GHz was measured with a source-modulated millimeter-wave spectrometer and that between 600 and 1600 GHz with a far-infrared sideband spectrometer. The far infrared spectrum from 30 to 360 cm-1 was measured with a Bruker IFS 120 HR interferometer attached to a 3 m long cell. We have assigned 224 submillimeter-wave lines and 1695 FIR lines. These observed data were supplemented by a large number of ground state combination differences derived from rotation-vibration bands of H2Te, and the resulting large data set was analyzed by means of a modified Watson Hamiltonian. Accurate sets of rotational and centrifugal distortion constants for all eight tellurium isotopomers were obtained.

Journal Article↗
PubMed1996

[The plasma level of kanamycin after intravenous and intramuscular injections in horses].

A therapeutical dose of kanamycin was tested intravenously and intramuscularly in four normal standardbreds and plasma concentrations were measured over a 12 hour period. Plasma levels exceeded a minimum inhibitory concentration of 4 micrograms/ml within only 15 minutes for 8 hours both after i.v. and i.m. injection. Kanamycin revealed a mean plasma half life of 2.3 hours. Bioavailability of an intramuscular dose was about 76%. The pharmacokinetic parameters demonstrate the rapid onset of antibacterial plasma levels of the test compound. A dose regimen for horses of two times daily 5 mg/kg body weight ensures therapeutically effective plasma levels. The risk of accumulation as well as nephro- or ototoxic side effects are negligible at short-term treatment.

Animals↗
PubMed1995

Effects of the tachykinin NK1 receptor antagonist, RP 67580, on central cardiovascular and behavioural effects of substance P, neurokinin A and neurokinin B.

1. We have investigated the effects of the non-peptide NK1 tachykinin receptor antagonist, RP 67580, and its inactive enantiomer, RP 68651, on the cardiovascular and behavioural responses to substance P (SP), neurokinin A (NKA) and neurokinin B (NKB) injected intracerebroventricularly (i.c.v.) in conscious rats. 2. The SP and NKA (25 pmol)-induced increases in blood pressure (BP) and heart rate (HR) were of the same magnitude. The cardiovascular responses to both peptides were associated with excessive grooming behaviour and wet dog shakes (WDS). Relative to SP, NKA was weaker in inducing hindquarter grooming (HG), but more effective in eliciting WDS. The cardiovascular response to NKB (50 pmol) comprised an increase in BP and HR, while the behavioural response was weak. 3. RP 67580 (100 pmol), injected 10 or 30 min prior to SP, effectively inhibited the cardiovascular and behavioural responses to the peptide whereas lower doses were ineffective. Pretreatment with 500 pmol of RP 67580, 10 or 30 min prior to SP, reduced the BP response. Of the behavioural manifestations, only face washing was attenuated when the antagonist was injected 10 min before SP. At 2500 pmol, the antagonist exaggerated the BP response to the peptide without affecting the behavioural response. RP 68651 (100 or 2500 pmol) did not modify the central responses to SP. 4. Neither RP 67580 nor RP 68651 (100 pmol), affected the cardiovascular and behavioural responses to NKA or NKB. 5. Our results indicate that RP 67580 is a selective and high affinity antagonist at central NK1 tachykinin receptors in the rat.

Animals↗
PubMed1995

Expression of Shigella dysenteriae serotype 1 O-antigenic polysaccharide by Shigella flexneri aroD vaccine candidates and different S. flexneri serotypes.

The potential utility of Shigella flexneri aroD vaccine candidates for the development of bi- or multivalent vaccines has been explored by the introduction of the genetic determinants rfp and rfb for heterologous O antigen polysaccharide from Shigella dysenteriae serotype 1. The serotype Y vaccine strain SFL124 expressed the heterologous antigen qualitatively and quantitatively well, qualitatively in the sense of the O antigen polysaccharide being correctly linked to the S. flexneri lipopolysaccharide R3 core oligosaccharide and quantitatively in the sense that typical yields were obtained, with ratios of homologous to heterologous O antigen being 4:1 for one construct and 1:1 for another. Moreover, both polysaccharide chains were shown to be linked to position O-4 of the subterminal D-glucose residue of the R3 core. In contrast to the hybrid serotype Y SFL124 derivatives, analogous derivatives of serotype 2a vaccine strain SFL1070 did not elaborate a complete heterologous O antigen. Such derivatives, and analogous derivatives of rough, O antigen-negative mutants of SFL1070, formed instead a hybrid lipopolysaccharide molecule consisting of the S. flexneri lipid A R3 core with a single repeat unit of the S. dysenteriae type 1 O antigen. Introduction of the determinants for the S. dysenteriae type 1 O antigen into a second serotype 2a strain and into strains representing other serotypes of S. flexneri, revealed the following for the expression of the heterologous O antigen: serotypes 1a, 1b, 2a, and 5a did not produce the heterologous O antigen, whereas serotypes 2b, 3a, 3b, 4a, 4b, 5b, and X did.

Bacterial Proteins↗
PubMed1994

The consequences of nitrofurantoin-induced oxidative stress in isolated rat hepatocytes: evaluation of pathobiochemical alterations.

Oxidative stress was induced in isolated rat hepatocytes by incubation with nitrofurantoin in the absence and presence of the GSSG reductase inhibitor BCNU. In both cases nitrofurantoin markedly reduced glutathione but exerted cytotoxicity as measured by LDH release and loss of intracellular potassium only in BCNU pretreated cells. The onset of cytotoxicity was accompanied by an increase of lipid peroxidation. Oxidation of protein thiols, however, could not be detected in the early phase of cell damage. The cytoprotective activity of N-acetyl-cysteine > dithiothreitol = deferoxamine revealed the substantial importance of glutathione for cellular defence and the sensitivity of not yet identified thiol-dependent targets of oxidative stress.

Acetylcysteine↗
PubMed1994

The role of glutathione and protein thiols in CBrCl3-induced cytotoxicity in isolated rat hepatocytes.

The role of glutathione (GSH) and protein thiols in the pathobiochemical process of CBrCl3 cytotoxicity was investigated in isolated hepatocytes. Administration of 0.5, 1.0 and 1.5 mmol/l CBrCl3 affected cellular viability as assessed by trypan blue exclusion, release of lactate dehydrogenase and loss of intracellular potassium in a dose-dependent manner. Intracellular glutathione and the capacity to reduce 3-(4,5-dimethylthiazolyl-2-)-2,5-diphenyltetrazolium bromide (MTT, thiazolyl blue) decreased almost independently of the CBrCl3 concentration. Protein thiols were not markedly oxidized in the presence of CBrCl3. However, compromising cellular defence mechanisms by either inhibition of glutathione regeneration or depletion of glutathione enhanced the cytotoxicity of CBrCl3 and induced a loss of protein thiols in the late phase of cellular injury. Under these conditions the thiol-dependent Na+,K+ATPase revealed high sensitivity towards CBrCl3. Thus, glutathione proved to exert effective cytoprotection, and sulfhydryl groups of particular proteins were supposed to be an important target of radical attack.

Animals↗
PubMed1993

Trichlorobromomethane-induced changes of purine nucleotides in hepatocytes.

The changes in nucleotide content during CBrCl3 treatment were investigated. In the first 5-10 minutes a significant ATP decrease was detected. The GTP loss leading to 57% of the initial level after 10 min surpasses the ATP loss which leads to 70% of the initial value after 10 min. The increase in uric acid is not only the result of CBrCl3 induced reaction, because of no significant changes in adenine and hypoxanthine values. The uric acid pool reflected different influx and efflux processes. These changes were compared with nucleotide degradation and accumulation of nucleotide degradation products during anoxia.

Adenosine Triphosphate↗
PubMed1992

[In vitro studies of intestinal absorption and biotransformation of furazolidone].

The intestinal biotransformation and absorption of the nitrofuran furazolidone were investigated in isolated gut cells and in the isolated perfused gut. In case of inhibiting furazolidone metabolism by high oxygen tension almost equal concentrations of the parent compound were measured on the mucosal and serosal side of the perfused gut segments. Lowering oxygen supply in order to adjust it to physiological conditions caused a complete degradation of furazolidone in isolated gut cells. Accordingly, hardly any unchanged furazolidone was detected on the serosal side of the isolated perfused gut. An open-chain cyanometabolite was formed in both systems indicating a reductive metabolic process which induces highly reactive intermediates. This metabolite also reached the serosal side of the gut representing the systemic circuit. Thus, the low systemic bioavailability is due to the considerable intestinal metabolism rather than a limited absorption. Unknown metabolites will reach the systemic circuit, the toxic potential of which is still obscure. Independent of its metabolic degradation, thus probably due to its redox cycle furazolidone inhibited intestinal functions as e. g. the flow of water and the transport of sodium.

Animals↗
PubMed1981

Alleviation of performance deficits of depression through thermal biofeedback training.

Explored thermal biofeedback as a method of reducing performance deficits associated with depression. A depressed and nondepressed control group and a depressed group given pretreatment with biofeedback were (N = 30) compared on their performance on an escape/avoidance task. As predicted by the learned helplessness model of depression, depressed controls showed significantly poorer performance than both other groups. The depressed biofeedback and nondepressed control groups did not differ from one another. Implications for alleviation of depression are discussed.

Achievement↗