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Biomedical subjects

E Richter

Publications and source records attributed to E Richter.

At least 109 records · Page 6Linked to original sources
PubMed1998

[Esophageal scintigraphy of Zenker's diverticula before and after diverticulotomy].

AIM: The filling and evacuation of Zenker's diverticula were scintigraphically examined before and after operation to quantify their functional relevance. These results were correlated with the symptoms of the patients and the findings of the barium swallow x-ray examination using cineradiography. METHODS: Sequential and static esophageal scintigraphies were performed in 17 patients with Zenker's diverticulum before and after laser surgical diverticulotomy. We used a gamma camera system in 45 degrees LAO-position after application of 15 ml of tea which was marked with 99mTc-DTPA. Filling and evacuation of the diverticulum were expressed in proportion to the administered activity. Relative volumes of the diverticula were obtained from cineradiography by using the height of the neighbouring cervical vertebra, and the clinical symptoms were divided into 4 groups. RESULTS: Zenker's diverticula could be verified visually and quantitatively by scintigraphy. The precise temporal course of the reduction of activity in the diverticulum was exactly determined. The scintigraphic retentions correlated with the x-ray volumes with a coefficient ranging from 0.55 to 0.85. Clinical symptoms also were not very closely related to scintigraphic and x-ray findings, respectively. CONCLUSION: The esophageal scintigraphy allows quantification of the filling and evacuation of Zenker's diverticula, thus it is suitable for objectivization of the functional relevance of the diverticula. That's why the esophageal scintigraphy should be taken to the diagnosis of diverticula in addition to the clinic and the x-ray examinations. The method is especially useful to evaluate the results after diverticulotomy.

Aged↗
PubMed1998

Influence of radioiodine therapy on urinary iodine excretion.

AIM: In 214 patients with benign thyroid diseases the time-course of urinary iodine excretion (UIE) was investigated in order to identify changes after radioiodine therapy (RITh). METHOD: UIE was measured photometrically (cerium-arsenite method) and related to urinary creatinine on the first and last day of the radioiodine test and then three days, seven days, four weeks, and six months after 131I administration. RESULTS: As compared with the level found immediately before radioiodine therapy, median UIE had almost doubled four weeks after therapy and was still significantly elevated six months after therapy. This increase correlated significantly with the target volume as measured by scintigraphy and sonography. CONCLUSIONS: The persistent elevation of UIE for months after RITh is a measure of treatment-induced damage to thyrocytes. Therefore, in view of the unfavourable kinetics of iodine that follow it, RITh should if possible be given via a single-dose regime.

Antithyroid Agents↗
PubMed1998

5% Me2SO is sufficient to preserve stem cells derived from cord blood.

On the basis of historical findings, 10% dimethylsulfoxide is still used to cryopreserve stem cells. We studied a final concentration of 5% dimethylsulfoxide in cryopreservation of cord blood-derived stem cells in autologous plasma. In our opinion, a final concentration of 5% dimethylsulfoxide in autologous plasma without further additives is sufficient for cryopreservation of cord blood stem cells in a banking routine.

Blood Banks↗
PubMed1998

Actinomycotic splenitis and intestinal volvulus in an alpaca (Lama pacos).

Morphologic, microbiologic, and polymerase chain reaction amplification techniques were used to evaluate an alpaca (Lama pacos) with splenitis and intestinal volvulus. The intestinal volvulus produced a severe necrosuppurative typhlocolitis associated with vascular thrombosis and was most likely the cause of death of this animal. In addition, this animal had multiple coalescing abscesses affecting most of the splenic tissue. The isolation of Actinomyces spp. from the spleen and the morphology of the colonies when stained with Gram and Steiner stains support a diagnosis of splenic actinomycosis.

Abscess↗
PubMed1998

Photographic documentation of acute radiation-induced side effects of the oral mucosa.

BACKGROUND: Radiotherapy in cancer of the head and neck induces cutaneous and mucosal reactions. These must be carefully assessed and documentated to control the accuracy of individual treatment, the overall toxicity of particular treatment schedules, the efficacy of prophylaxis and treatment and to determine the adequate therapy of treatment sequelae depending on the severity of the reactions. The accurate classification of lesions according to internationally accepted schedules (WHO/RTOG/CTC) is indispensable for the comparison of radiotherapy treatment results and efficacy of supportive care. METHODS: While the treatment of cancer depends on tumor stage and medical circumstances of the patient and is more or less standardized, prophylaxis and treatment of side-effects is highly variable. Discussing an optimized prophylaxis and therapy of oral mucositis, the problem of accurate classification and documentation emerged. The verbal description of mucosal lesions is open to many subjective interpretations. Photographic documentation seems a suitable method to optimize the grading of toxicity. RESULTS: A photographic survey of typical lesions for each grade of toxicity is a tool to reach several aims in one step. Toxicity of an individual patient may be compared with representative photographic examples in daily routine to decide quickly on the grade of toxicity. Subjective differences due to intra- and interpersonal variability of the evaluating radiooncologist will be reduced. The efficacy of treatment can be proven by accurate documentation. Randomized clinical studies concerning prophylaxis and treatment of oral mucositis will provide more reliable results if evaluation of toxicity grading is standardized by photographs. CONCLUSIONS: Photographic documentation of lesions of the oral mucosa might be the best means to reduce interindividual subjectivity in grading. It is a valuable appendix to standard classification systems and only concerns the visible signs of mucosal lesions. However, the exact grading of mucositis is only possible with additional clinical information about pain and nutritional situation.

Documentation↗
PubMed1997

Characterization of two pituitary GH3 cell sublines partially resistant to apoptosis induction by okadaic acid.

Pituitary GH3 cells die by apoptosis when treated with okadaic acid, a specific inhibitor of ser/thr phosphatases. Incubations starting at concentrations of 5 and 12.5 nM followed by stepwise rises resulted in two populations (the S1 and S2 sublines) that proliferated at initially lethal 30 nM. Cells were partially resistant to higher concentrations of okadaic acid and its derivative methyl okadaate. Toxicity of the structurally distinct inhibitors cantharidic acid and calyculin A was differently affected in the two resistant lines. The enhanced expression of the P-glycoprotein was one mechanism of resistance in S1 and S2. Resistance was reversed completely (S1) or partially (S2) by the addition of verapamil. In addition, phosphatase activity, presumably PP2A, was increased in S2. Therefore, pharmacokinetic and pharmacodynamic mechanisms can protect pituitary GH3 cells from apoptotic cell death by okadaic acid.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Diameter-Selective Raman Scattering from Vibrational Modes in Carbon Nanotubes

Single wall carbon nanotubes (SWNTs) that are found as close-packed arrays in crystalline ropes have been studied by using Raman scattering techniques with laser excitation wavelengths in the range from 514.5 to 1320 nanometers. Numerous Raman peaks were observed and identified with vibrational modes of armchair symmetry (n, n) SWNTs. The Raman spectra are in good agreement with lattice dynamics calculations based on C-C force constants used to fit the two-dimensional, experimental phonon dispersion of a single graphene sheet. Calculated intensities from a nonresonant, bond polarizability model optimized for sp2 carbon are also in qualitative agreement with the Raman data, although a resonant Raman scattering process is also taking place. This resonance results from the one-dimensional quantum confinement of the electrons in the nanotube.

Journal Article↗
PubMed1997

Studies on propafenone-type modulators of multidrug-resistance IV1): synthesis and pharmacological activity of 5-hydroxy and 5-benzyloxy derivatives.

A series of 5-hydroxy and 5-benzyloxy analogs of the antiarrhythmic and multidrug resistance (MDR) modulating drug propafenone was synthesized and the MDR-modulating activity of the compounds was evaluated using a daunomycin efflux assay system. The key step of the synthesis is the selective reduction of the double bond in 1 without cleavage of the benzyl group thus leading to the phenol 3. Alkylation with epichlorohydrine followed by nucleophilic epoxide ring opening gave the benzylated target compounds 5a-d. Subsequent cleavage of the benzyl group gave the 5-hydroxy analogs 6a-d. Structure activity relationship studies showed, that the 5-hydroxy derivates 6a-d fit the log P/log potency correlation line previously established for a series of propafenone analogs. In contrast, all four 5-benzyloxy analogs 5a-d showed almost identical EC50 values, independent of their log P value.

Anti-Arrhythmia Agents↗
PubMed1997

Tumour necrosis factor alpha promoter gene polymorphism in sarcoidosis.

Biallelic polymorphisms in the promoter region of the TNF-alpha gene (TNFA) and in the first intron of the TNF-beta gene (TNFB) have been associated with variation in TNF-alpha production and with susceptibility to severe diseases. Among other functions, TNF-alpha plays a pivotal role in regulatory aspects of granuloma formation and sustenance. In sarcoidosis, a systemic granulomatous disorder of unknown aetiology, the clinical course of the disease has been associated with the patient's individual capacity of spontaneous TNF-alpha production by alveolar macrophages. We determined the TNFA and TNFB polymorphisms in 101 patients with pulmonary sarcoidosis and 216 healthy blood donors. A highly significant shift to the more uncommon TNFA2 allele was found in the Löfgren syndrome patient group, which represents the acute form of the disease with frequent spontaneous remission. The results show that gene frequencies of the TNFA gene variation are significantly different within the clinical forms of sarcoidosis, indicating that genetic predisposition for TNF-alpha production may play a role in the pathogenesis of the disease.

Humans↗
PubMed1997

Systemic infection with Mycobacterium genavense following immunosuppressive therapy in a patient who was seronegative for human immunodeficiency virus.

We describe, to our knowledge, the first case of disseminated Mycobacterium genavense infection in a patient who was seronegative for human immunodeficiency virus. The patient, a 47-year-old woman, had been previously treated with immunosuppressive drugs for 9 months to control an unclassified immunologic disorder characterized by intermittent fever and inflammatory pulmonary, hepatic, and dermal infiltrates. Antemortem and postmortem examinations revealed the presence of numerous mycobacteria in the bone marrow, spleen, kidneys, and lungs; these organisms failed to grow in vitro and were identified as M. genavense by 16S rRNA gene sequencing. This case illustrates that systemic M. genavense infections are not restricted to patients with AIDS but can also occur in otherwise immunocompromised patients.

Female↗
PubMed1997

Simultaneous solid-phase extraction and gas chromatographic-mass spectrometric determination of hemoglobin adducts from tobacco-specific nitrosamines and aromatic amines.

A new method for the simultaneous determination of hemoglobin adducts from aromatic amines and tobacco-specific nitrosamines (TSNA) is described. After mild base-catalysed hydrolysis releasing aromatic amines and the TSNA adduct 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB), the extraction, cleanup, and concentration are performed by a one-step procedure using C18 cartridges. Determination in the picograms per gram of hemoglobin range by gas chromatography-mass spectrometry with negative chemical ionization requires a separate derivatization procedure with pentafluoropropionic anhydride and pentafluorobenzoylchloride for aromatic amines and HPB, respectively. The method is shown to be quantitative, reproducible, and applicable to the determination of hemoglobin adducts from monocyclic and bicyclic aromatic amines as well as TSNA in smokers and nonsmokers.

Amines↗
PubMed1997

IS6110 fingerprinting of drug-resistant Mycobacterium tuberculosis strains isolated in Germany during 1995.

The epidemiological relatedness of drug-resistant Mycobacterium tuberculosis strains isolated in Germany in 1995 was evaluated by the standardized IS6110 fingerprinting method. Altogether, 196 M. tuberculosis isolates from 167 patients were analyzed. A large degree of IS6110 polymorphism was found, ranging from 1 to 20 copies. Multiple isolates from one patient generally remained stable over a period of up to 1 year. However, one strain showed an additional fragment 7 months after the first isolate was obtained. Isolates from 55 patients (33%) showed identical fingerprint patterns or fingerprint patterns that differed only in one band, and thus they were clustered in 22 fingerprint groups. Specific transmission links could be established between members of four groups, e.g., transmission by family contacts. In one case, transmission of a multidrug-resistant strain to a patient initially infected with a drug-susceptible strain could be shown. Besides these fingerprint groups, 30 of the 167 isolates (approximately 18%) could be grouped in two fingerprint clusters with a similarity of at least 78%. Approximately 60% of the patients of these two clusters were known to be immigrants from the former Soviet Union, and one patient is still living in Belarus. In conclusion, our results indicate that (i) transmission of drug-resistant strains contributes substantially to the emergence of drug-resistant tuberculosis in Germany and (ii) drug-resistant M. tuberculosis strains were presumably carried over from the former Soviet Union to Germany by immigrants.

Commonwealth of Independent States↗
PubMed1997

Biomonitoring exposure to environmental tobacco smoke (ETS): a critical reappraisal.

1 The most frequently used biomarkers for exposure to environmental tobacco smoke (ETS) are cotinine and thiocyanate in body fluids, carboxyhaemoglobin in red blood cells (COHb) and carbon monoxide in the expired air. Although not ideal, cotinine in blood, saliva or urine is an established biomarker for ETS exposure within the past 1-3 days. Comparison with cotinine concentrations in cigarette smokers reveals that passive smokers take up less than 1/100 of the nicotine dose of smokers. 2 Biomonitoring data available for the ETS-related exposure to genotoxic substances comprise uptake of benzene, polycyclic aromatic hydrocarbons (PAH), aromatic amines, tobacco-specific nifrosamines (TSNA), electrophilic compounds giving rise to urinary thioethers, mutagens causing urinary mutagenic activity and the formation of various DNA adducts. With the exception of TSNA, these biomarkers are related to chemicals occurring ubiquitously in the environment and in the food. As a consequence, the background levels in unexposed nonsmokers are high compared to the observed increases (if any) associated with ETS exposure. 3 Some markers of biological effects, which, by definition, are non-specific with regard to the underlying exposure, have also been investigated in relation to ETS exposure. These markers comprise cytogenetic effects, aryl hydrocarbon hydroxylase (AHH) induction, urinary hydroxyproline excretion and various factors indicative of cardiovascular risks. The available data suggest that passive smoking is associated with a small induction of placental AHH and also with effects on cardiovascular risk markers. The latter findings in particular may be confounded by other risk factors, which have been observed to be more frequent in passive smokers than in unexposed nonsmokers.

Benzene↗
PubMed1996

Effect of medium conductivity and composition on the uptake of propidium iodide into electropermeabilized myeloma cells.

The effects of ionic composition and conductivity of the medium on electropermeabilization of the plasma membrane of mammalian cells were studied. Temporal and spatial uptake of propidium iodide (PI) into field-treated cells was measured by means of flow cytometry, spectrofluorimetry and confocal laser scanning microscopy. Murine myeloma cells were electropulsed in iso-osmolar solutions. These contained 10-100 micrograms ml-1 PI at different conductivities (0.8-14 mS cm-1) and ionic strengths, adjusted by varying concentrations of K+, Na+, Cl- and SO4(2-). Field-induced incorporation of PI into reversibly permeabilized cells was (almost) independent of ionic composition and strength (at a fixed medium conductivity), but increased dramatically with decreasing medium conductivity at a fixed field strength. The time-course of PI uptake (which apparently reflected the resealing process of the membrane) could be fitted by single-exponential curve (relaxation time about 2 min in the absence of Ca2+) and was independent of medium conductivity and composition. These and other data suggested that the expansion of the 'electroleaks' during the breakdown process is field-controlled and depends, therefore, on the (conductivity-dependent) discharging process of the permeabilized membrane. The threshold field strength for dye uptake increased with increasing K+ concentration (about 0.6 kV cm-1 in K(+)-free, NaCl-containing medium and about 0.9 kV cm-1 in 30 mM KCl-containing medium). Also, the spatial uptake pattern of PI shifted from an asymmetric permeation through the cell hemisphere facing the anode to a more symmetric uptake through both hemispheres. These results suggested that the generated potential is superimposed on the (K(+)-dependent) resting membrane potential. Taking this into account, the breakdown voltage of the membrane was estimated to be about 1 V.

Animals↗
PubMed1996

Human dermal fibroblasts express eotaxin: molecular cloning, mRNA expression, and identification of eotaxin sequence variants.

Recently we discovered and purified a novel beta-chemokine with eosinophil specific chemotactic activity from supernatants to long-term TNF-alpha stimulated dermal fibroblasts. Using degenerated specific oligonucleotides based on partial amino acid sequence data and a PCR protocol, we obtained different clones sharing high sequence homology with this novel chemokine and with human eotaxin cDNA. Semi-quantitative RT-PCR experiments using eotaxin-specific primers indicate low constitutive eotaxin mRNA expression in human dermal fibroblasts which is upregulated by IL-1 alpha and TNF-alpha within 6 hrs and modulated by IFN-gamma. While IL-1 alpha-induced eotaxin mRNA accumulation is transient, long-term stimulation with TNF-alpha resulted in a further increase of eotaxin mRNA.

Amino Acid Sequence↗
PubMed1996

The identification of 11 beta-hydroxysteroid dehydrogenase as carbonyl reductase of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.

The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NC), which is generated by nitrosation of nicotine, requires enzymatic activation by cytochrome-P450-mediated alpha-carbon hydroxylation to yield particularly powerful carcinogenic alkylating intermediates. Pyridine-N-oxidation and carbonyl reduction are detoxification pathways, the latter by providing the functional hydroxy moiety necessary for glucuronosylation and final excretion of NC. For more than a decade, the enzyme responsible for NC carbonyl reduction has awaited characterization. In the present study, we demonstrate that the NC carbonyl reductase is identical to 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD), the physiological function of which is the oxidoreduction of glucocorticoids. We conclude that the expression of 11 beta-HSD (together with glucuronosyl transferase) may have profound influence on the carcinogenic potency of NC and that many compounds of endogenous and exogenous origin, which are known to be substrates or inhibitors of 11 beta-HSD, may modulate NNK-induced carcinogenicity by competing for the same enzyme. In light of the known species and tissue differences in the expression of 11 beta-HSD isozymes, important aspects of NNK-induced tumorigenesis, such as metabolic activation versus inactivation or organospecificity, can now be re-evaluated.

11-beta-Hydroxysteroid Dehydrogenases↗