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K König

Publications and source records attributed to K König.

At least 37 records · Page 2Linked to original sources
PubMed2000

Lipopolysaccharide induces distinct alterations in the microtubule cytoskeleton of monocytes.

Microtubules are obligate functional elements of almost all eukaryotic cells. They are involved in a broad range of essential cellular functions and structural changes of this system may trigger cell death. Recently, we have reported that lipopolysaccharides inhibit in vitro microtubule formation due to exclusion of microtubule-associated proteins. The distinct epitopes of lipopolysaccharides responsible for these effects and the in vivo relevance of these data are unknown. Therefore, this study was conducted to elucidate the effects of lipid A, the biologically active motif of lipopolysaccharides, on microtubule formation in vitro and to prove whether lipopolysaccharides affect the microtubule architecture of cultured human monocytes in vivo. Despite a dose- and pH-dependent inhibition of microtubule formation by lipopolysaccharides, inhibition of microtubule assembly could be mimicked by lipid A. Near-infrared two-photon microscopy revealed that human peripheral blood monocytes accumulate lipopolysaccharides. A vesicular distribution pattern of lipopolysaccharides within the monocytes was observed. Confocal laser scanning microscopy demonstrated alterations in the microtubule architecture of monocytes after incubation with lipopolysaccharides. Lipid A seems to be responsible for the observed crosstalk between lipopolysaccharides and microtubule proteins. Furthermore, our data indicate that lipopoly-saccharides may affect the microtubule architecture in human monocytes after intracellular accumulation directly. Therefore, we conclude, that the microtubule cytoskeleton is an essential intracellular target for sepsis-relevant bacterial components such as lipopolysaccharides.

Animals↗
PubMed2000

Multiphoton microscopy in life sciences.

Near infrared (NIR) multiphoton microscopy is becoming a novel optical tool of choice for fluorescence imaging with high spatial and temporal resolution, diagnostics, photochemistry and nanoprocessing within living cells and tissues. Three-dimensional fluorescence imaging based on non-resonant two-photon or three-photon fluorophor excitation requires light intensities in the range of MW cm(-2) to GW cm(-2), which can be derived by diffraction limited focusing of continuous wave and pulsed NIR laser radiation. NIR lasers can be employed as the excitation source for multifluorophor multiphoton excitation and hence multicolour imaging. In combination with fluorescence in situ hybridization (FISH), this novel approach can be used for multi-gene detection (multiphoton multicolour FISH). Owing to the high NIR penetration depth, non-invasive optical biopsies can be obtained from patients and ex vivo tissue by morphological and functional fluorescence imaging of endogenous fluorophores such as NAD(P)H, flavin, lipofuscin, porphyrins, collagen and elastin. Recent botanical applications of multiphoton microscopy include depth-resolved imaging of pigments (chlorophyll) and green fluorescent proteins as well as non-invasive fluorophore loading into single living plant cells. Non-destructive fluorescence imaging with multiphoton microscopes is limited to an optical window. Above certain intensities, multiphoton laser microscopy leads to impaired cellular reproduction, formation of giant cells, oxidative stress and apoptosis-like cell death. Major intracellular targets of photodamage in animal cells are mitochondria as well as the Golgi apparatus. The damage is most likely based on a two-photon excitation process rather than a one-photon or three-photon event. Picosecond and femtosecond laser microscopes therefore provide approximately the same safe relative optical window for two-photon vital cell studies. In labelled cells, additional phototoxic effects may occur via photodynamic action. This has been demonstrated for aminolevulinic acid-induced protoporphyrin IX and other porphyrin sensitizers in cells. When the light intensity in NIR microscopes is increased to TW cm(-2) levels, highly localized optical breakdown and plasma formation do occur. These femtosecond NIR laser microscopes can also be used as novel ultraprecise nanosurgical tools with cut sizes between 100 nm and 300 nm. Using the versatile nanoscalpel, intracellular dissection of chromosomes within living cells can be performed without perturbing the outer cell membrane. Moreover, cells remain alive. Non-invasive NIR laser surgery within a living cell or within an organelle is therefore possible.

Biological Science Disciplines↗
PubMed2000

Red light kills bacteria via photodynamic action.

With the increase in the number of antibiotic resistant strains of microorganism, the search for alternative treatments of microbial infections becomes all the more important. We report a novel method for bacterial inactivation based on the optical excitation of the naturally occurring (endogenous) photosensitzing porphyrins by red light. In particular, the pathogenic Gram-positive porphyrin producing ATCC strains Propionibacterium acnes, Actinomyces odontolyticus and Porphyromonas gingivalis were investigated. Sensitive autofluorescence spectroscopy revealed that these bacteria naturally synthezise the fluorescent photosensitizer protoporphyrin IX. In addition, bacterial plaque samples of periodontitis patients were studied. Non-labeled fluorescent bacterial colonies were exposed to red light at 632.8 nm, 100 mW/cm2 light intensity and 360 J/cm2 energy density using a helium-neon laser. The survival rate after a single phototreatment with red light was found to be 0.58 +/- 0.09 in the case of Propionibacterium acnes, 0.30 +/- 0.04 in Actinomyces odontolyticus and 0.59 +/- 0.10 in Porphyrormonas gingivalis compared to non-exposed bacteria suspensions. No photoeffect was found for the bacterium Streptococcus mutans which exhibited no detectable porphyrin autofluorescence. Red-light exposed plaque samples of patients showed significant reduction of colony forming units by 50% as well as a pronounced photoeffect on the pigmented species Prevotella intermedia. Taken together, these results suggest the treatment with red light can be potentially employed as an therapeutic method to inactivate certain pathogenic strains of porphyrin producing bacteria without the use of external photosensitizers.

Anti-Bacterial Agents↗
PubMed1999

Technical advance: near-infrared femtosecond laser pulses as a novel non-invasive means for dye-permeation and 3D imaging of localised dye-coupling in the Arabidopsis root meristem.

We have used near-infrared femtosecond Titanium: Sapphire laser pulses as novel non-invasive means for dye loading into various cell types of the Arabidopsis root meristem, and by 3D imaging have assessed the extent of dye coupling between the meristematic cells. The post-embryonic primary root of Arabidopsis thaliana has an invariant ontogeny and fixed cellular organisation which makes it an attractive model system to study developmental events involving cell fate determination, cellular differentiation and pattern formation. Local intercellular communication and local transmission of positional signals are likely to play a pivotal role in cell proliferation and regulation of differentiation. We have therefore examined the extent to which the constituent cells in the root meristem are symplastically coupled. Following laser-assisted loading of membrane impermeate fluorescent dye propidium iodide (PI) in single cells, we show by time-lapse and 3D imaging that in the root tip all undifferentiated cells are dye-coupled. When PI is permeated into the central cells, it rapidly moved into the adjacent initials of the columella, cortex, pericycle and stele. Interestingly, when only either of the initials were loaded with the dye, it never moved into any of the central cells. Amongst the epidermal cells, the differentiated hair cells are symplastically isolated. Our data provide evidence (1) for differential dye-coupling behaviour between quiescent centre cells and the neighbouring initials; (2) that cells in the root are coupled during stages at which the cell-lineage pattern is formed and that it becomes progressively secluded as they differentiate and the pattern is fixed. Taken together, our NIR-laser mediated approach is highly efficient and has numerous potential applications for non-invasive permeation of dyes in different cell types.

Arabidopsis↗
PubMed1999

Long-term follow-up of the 137Cs body burden of individuals after the Chernobyl accident--a means for the determination of biological half-lives.

Since 1986, the year of the Chernobyl accident, 137Cs body burdens of members of a Bavarian reference group have been measured monthly. These time series were individually analyzed with respect to the long-term component T1 of the biological half-life of 137Cs, assuming a continuous 137Cs intake, which is based on reference data for the food consumption in the Federal Republic of Germany. In 13 individual cases, T1 was additionally deduced after single ingestion of 137Cs. The resulting T1 deduced from continuous and from single intake agreed within about 20%. Using the results of 64 cases, it is shown that there is a dependency of T1 with sex for adults. T1 for children and adults are also significantly different. When combining all data for children, adult females and adult males, significant correlations of T1 with age, 40K and body mass can be found. Since body mass, for example, is a parameter very simple to measure, the given correlations are useful for practical purposes.

Adolescent↗
PubMed1999

Intracellular nanosurgery with near infrared femtosecond laser pulses.

We report on laser-assisted knocking out of genomic nanometer-sized regions within the nucleus of living cells. The intranuclear nanosurgery was possible by application of highly intense near infrared femtosecond laser pulses. The non-contact laser treatment was performed within a closed sterile cell chamber. The destructive multiphoton effect was based on 10(12) W/cm2 light intensities and limited to a sub-femtoliter focal volume of a high numerical aperture objective. We used the intracellular nanoscalpel for highly precise non-contact dissection of Hoechst-labelled chromosomes within a nucleus of a living Chinese hamster ovary cell. Following laser treatment, the cell remained alive and did not show any signs of membrane perturbation. The use of near infrared pulses provide the possibility of non-invasive intracellular nanoprocessing also within living tissue in depths of more than 100 microns.

Animals↗
PubMed1999

Time-gated in vivo autofluorescence imaging of dental caries.

Laser-induced time-resolved autofluorescence from carious lesions of human teeth was studied by means of ultrashort pulsed laser systems, time-correlated single photon counting and time-gated imaging. Carious regions exhibited a slower fluorescence decay with a main 17 ns fluorescence lifetime than healthy hard dental tissue. The long-lived fluorophore present in carious lesions only emits in the red spectral region. Fluorescence decay time and spectral characteristics are typical of fluorescent metal-free porphyrin monomers. The spatial distribution of the long-lived endogenous porphyrin fluorophore within the tooth material was detected by time-gated nanosecond autofluorescence imaging. In particular, high contrast video images were obtained with an appropriate time delay of 15 ns to 25 ns between excitation and detection due to the suppression of short-lived autofluorescence of healthy tissue. First in vivo applications are reported indicating the potential of time-resolved fluorescence diagnostics for early caries- and dental plaque detection.

Dental Caries↗
PubMed1998

Cerebral blood flow in chronic hydrocephalus--a parameter indicating shunt failure--new aspects.

Prediction of outcome after shunt-therapy in chronic hydrocephalus syndrome is uncertain. Pathology reveals an impairment of cerebral blood flow (CBF). Based on this, we evaluated CBF and its significance for the assessment of prognosis. In 21 patients (mean age 69 years) selected for surgery, CBF was measured by PET (15O-H2O) before, about one week and 7 months (n = 14) after shunting. CBF was computed by a 1-compartmental model in the territories of the ACA, MCA and PCA. One PET slice in the height of the maximum projection of both cellae mediae was chosen. CBF data were standardized by cluster analysis. Three CBFClusters with significantly different CBF levels prior to shunting in the ACA, MCA and PCA territory, respectively, referred to the sample average (38.2 ml/100 ml/min) were found. These CBFClusters differed in clinical outcome: almost 50% and 90% of patients improved clinically in CBFCluster I, with a perfusion level lower than average, after one week and 7 months, respectively. In contrast, patients of CBFCluster II with an average perfusion did not improve. CBF changes 7 months after shunting related to global CBF before surgery showed a relationship with the clinical course. Clinical outcome corresponded with preoperative global CBF values. Cerebral blood flow lower than average forecasts clinical improvement. Our results suggest that measurement of CBF adds to the indication for surgery.

Aged↗
PubMed1998

Treatment of elevated intracranial pressure by infusions of 10% saline in severely head injured patients.

The management of intracranial pressure (ICP) is a factor in outcome of patients with head trauma. However, recent studies have revealed that the current strategies, which have been applied to control ICP for adequate cerebral perfusion, are unsatisfactory. Against this background, the efficacy of short-term infusions of hypertonic saline on ICP was investigated. In severely head injured (SHI) patients, hypertonic saline (100 ml 10% NaCl) was administered when standard agents (mannitol, sorbitol, THAM) failed in reducing ICP. To evaluate the pressure reduction after saline infusions the resulting ICP relaxations were analysed statistically in respect to the parameters amplitude, duration and dynamic behaviour of the ICP responses. In 42 randomized relaxations, the relative ICP decrease was 43% [28%-58%] (median [interquartile range]). The corresponding pressure drop was 18 mmHg [15-27 mm Hg]. Relaxations lasted for 93 min [64-126 min] and a relative ICP minimum was reached 26 min [12-33 min] after infusion. In the individual cases the temporal course of the parameters amplitude and decline interval depict a tendency toward lower and higher values, respectively, under conditions of a generally increasing ICP. As expected, the infusion of hypertonic saline reduces ICP in patients suffering from SHI. The pressure drop, duration and dynamic behaviour are suspected to depend both on the pressure level to reduce and concomitant medications.

Adolescent↗
PubMed1998

[Current status of laser therapy in dermatology].

Indications for dermatological laser therapy have been enlarged during the last few years. In this article the physics and biophysics of laser therapy and the common laser systems in dermatology are described. Modern pulsed laser systems are combined with little side effects. Nevertheless, successfully used alternative methods should not be neglected.

Adult↗
PubMed1998

Direct beta measurements to determine in vivo whole-body activities of 90Sr in residents of the southern Urals: description of a new method.

For 44 individuals living in areas of the Southern Urals with historical 90Sr contamination, whole-body activities of this radionuclide were investigated using a new mobile detection system. Beta-particles from 90Sr/90Y decay were measured in vivo via two proportional counters mounted in front of the forehead and above the head, respectively. In order to correct for absorption by the skin, scalp thickness was measured using ultrasonic techniques. Corrections are given with respect to self-absorption by the bone matrix and absorption by hair. A procedure is described to extrapolate from measured 90Sr activity of the skull bone to total 90Sr skeleton burden. As a result, 90Sr whole-body activities of up to 50 kBq were recorded in the selected cohort. For the same individuals, 90Sr was measured via the detection of bremsstrahlung using an established whole-body counting device. The overall results of both systems agree within 15%, but differences exceeding a factor of 2 were observed in some cases.

Absorption↗
PubMed1998

Different patterns of change in narratives of men and women during analytical group psychotherapy.

Narratives of men and women concerning their interactions with other people were evaluated before and during analytically oriented group psychotherapy using the Core-Conflictual-Relationship-Theme (CCRT) method (Luborsky & Crits-Cristoph, 1990). Relationship patterns of men and women developed differently during therapy. Some gender stereotypes persisted, others changed. During therapy the proportion of negative responses in the narratives increased in the men. Change in the narratives was not related to change in self-reported symptoms. For group treatments, the results suggest that the gender of the patients has to be taken into account. Knowledge of different developmental patterns for men and women in groups can be important in regard to the expectations of therapists and their countertransference.

Adult↗
PubMed1998

European whole body counter measurement intercomparison.

In order to test the common quality standards for the performance of measurements of internal radioactivity, the European Commission funded a European intercomparison of whole body counters, which was organized and carried out by the Institut fuer Strahlenhygiene (part of the German Bundesamt fuer Strahlenschutz). Forty-four whole body counting facilities from forty-two institutions in nineteen countries (the fifteen member states of the European Union plus Hungary, the Czech Republic, Switzerland and Norway) took part in this intercomparison, which made it the most comprehensive ever carried out in Europe. For the study, the 70 kg tissue equivalent St Petersburg phantom was used with rods containing 40K, 57Co, 60Co, and 137Cs. The overall results of the whole body counter study were rather good.

Cesium Radioisotopes↗
PubMed1998

Laser tweezers are sources of two-photon excitation.

The most important application of continuous wave (cw) near infrared (NIR) microbeams in cellular and molecular biology are single-beam gradient force optical traps, also called "laser tweezers". Laser tweezers have been used for optical picoNewton force determination as well as for 3D cellular and intracellular micromanipulation, such as optical spermatozoa transportation in laser-assisted in vitro fertilization. Light intensities in the MW/cm2 range are necessary to confine motile spermatozoa in the optical trap. The enormous photon concentration in space and time results in non-resonant two-photon excitation of endogenous and exogenous absorbers with electronic transitions in the ultraviolet and visible spectral range. Trap-induced two-photon excitation of intracellular flurorophores can be used to study metabolism and vitality of motile cells without additional fluorescence excitation sources. Therefore, laser tweezers as sources of two-photon excitation may act as novel non-linear tools in cell diagnostics. The far red/NIR trapping radiation, in particular <800 nm, may also excite endogenous absorbers such as NAD(P)H, flavins, porphyrins and cytochromes. Excitation of these cellular absorbers may result in oxidative stress via type I and type II photooxidation processes. Severe non-linear-induced cell damage in a variety of cells confined in <800 nm traps was found. Two-photon induced destructive effects are enhanced in multimode traps due to longitudinal mode-beating phenomena. Pulsed laser sources are not suitable for safe optical trapping of living cells. The use of single frequency long-wavelength NIR traps (800 nm-1200 nm) for vital cell handling is recommended.

Animals↗
PubMed1998

Time-gated autofluorescence microscopy of motile green microalga in an optical trap.

Ultrafast time-gated fluorescence imaging of optically trapped single motile cells is presented. The biflagellar green microalga Haematococcus pluvialis was confined with picoNewton trapping forces in the focal volume of a high numerical aperture objective by near infrared multitraps. Trapping radiation of 100 mW power at the sample was provided by a Nd:YLF laser (1047 nm) operating in the cw mode. Simultaneously, cellular autofluorescence was excited with a 633 nm picosecond 80 MHz laser diode. An ultrafast gated intensified slow scan CCD camera system with a tunable gate width (200 ps-1 ms) and tunable time-delay (0-20 ns) between excitation and detection was used as fluorescence detector. We demonstrate fluorescence imaging of high temporal (sub-ns) and high spatial (sub-microm) resolution and fluorescence lifetime determination of intracellular autofluorescence based on chlorophyll excitation. Exposure to the herbicide DCMU resulted in an increase of fluorescence intensity and lifetime by 250% and 150%, respectively.

Chlorophyta↗
PubMed1998

New time-resolved techniques in two-photon microscopy.

Microscopy is traditionally a tool for determining biological structures. Many recent advances in optical microscopy involves the incorporation of spectroscopy techniques to monitor biochemical states of microscopic structures in living cells and tissues. By minimizing tissue photodamage, two-photon excitation microscopy provides a new opportunity to study the dynamics of biological systems on time scales from nanoseconds to hours. This review will focus on a number of these new methods: two-photon time-lapse microscopy, two-photon photoactivation, two-photon correlated spectroscopy, two-photon single particle tracking and two-photon lifetime microscopy.

Animals↗
PubMed1998

Laser scanning microscopy in enzyme histochemistry. Visualization of cerium-based and dab-based primary reaction products of phosphatases, oxidases and peroxidases by reflectance and transmission laser scanning microscopy.

The reflectance mode of confocal laser scanning microscopy is suitable to detect cerium-based primary reaction products of oxidases (CeIV-perhydroxide) and phosphatases (CeIII-hydroxy-phosphate converted into CeIV-perhydroxy-phosphate) as well as of DAB-based primary reaction products (Ni-DAB, Ni-FeII-DAB and CeIV-DAB complexes) of cytochrome C oxidase and peroxidases in vibratome, cryotome and semithin plastic sections. In combination with confocal detection 3D images with submicron spatial resolution can be obtained. Moreover, CeIV-perhydroxide, CeIV-perhydroxy-phosphate, CeIV-DAB complexes and catechol-DAB polymers are highly absorptive. Among other additives, especially stable nitroxyl radicals led to a distinct improvement of the DAB staining in terms of sensitivity and proper localization. This was proven in addition by means of blotting a horseradish peroxidase dilution series during several experiments. In sections it was easily possible to record reflectance signals and high transmission contrast at the wavelength of the exciting argon ion laser (preferentially 488 nm). The results of an imbibition study of cerium-containing model precipitates indicate that the cerium generally should be oxidized prior to observation because the index of refraction of CeIV compounds is considerably higher than that of the corresponding CeIII compounds. A comparative numerical assessment of reflection intensities from reflectant parts in morphologically similar sections is possible. Confocal laser scanning microscopy offers a unique way for high resolution detection of primary histochemical reaction products being sufficiently reflective and/or absorptive. The proposed techniques may open new methodological possibilities for basic research and for medical diagnosis.

3,3'-Diaminobenzidine↗