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Biomedical subjects

E Richter

Publications and source records attributed to E Richter.

At least 37 records · Page 2Linked to original sources
PubMed2002

Solution deposition of hydroxyapatite on titanium pretreated with a sodium ion implantation.

Titanium surfaces were treated by exposing them to a beam of sodium ions. Sodium titanate was shown to be incorporated within the oxidic titanium surface. The ion-implanted surfaces were examined for their reactivity by immersion in a simulated body fluid, which showed the formation of surface-bound hydroxyapatite. The surface was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and optical and electron microscopy. The surface hydroxyl concentration was determined using the nuclear reaction (1)H((15)N, alpha gamma)(12)C. Surface-related parameters that may affect hydroxyapatite nucleation are discussed in terms of the electrical double layer.

Durapatite↗
PubMed2002

Remission of cutaneous Mycobacterium haemophilum infection as a result of antiretroviral therapy in a Human Immunodeficiency Virus--infected patient.

We describe the first Mycobacterium haemophilum infection that occurred in a patient with human immunodeficiency virus in Germany and report 7 newly diagnosed cases of M. haemophilum infection. In the former case, a local M. haemophilum skin infection resolved as a result of successful antiretroviral therapy only; however, that clinical outcome may not be possible for more invasive forms of the disease.

AIDS-Related Opportunistic Infections↗
PubMed2002

Nitrosation of dietary myosmine as risk factor of human cancer.

The tobacco alkaloid myosmine was detected in nut and nut products [J. Agric. Food Chem. 46 (1998) 2703]. Upon nitrosation, myosmine yields 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) and N-nitrosonornicotine (NNN) [J. Agric. Food Chem. 48 (2001) 392]. NNN is a strong oesophageal carcinogen in rats. Metabolic activation of NNN leads to formation of DNA and protein adducts which release HPB upon hydrolysis. In the present study the time, pH and dose-dependent nitrosation of myosmine and its covalent binding to DNA was investigated. [5-(3)H]myosmine was incubated with nitrite for 1-24 h in buffer solutions adjusted to pH 1-6. At pH 2-4 myosmine was easily nitrosated and gave rise to two major products, HPB and NNN, and five minor not yet identified products. Maximal formation was achieved for HPB at pH 2 after 8 h (72% of total radioactivity) and for NNN at pH 3 after 8 h (16%). For DNA binding studies labeled myosmine was incubated under nitrosation conditions with calf thymus DNA. Within 3 h up to 0.1% of the radioactivity was covalently bound to DNA. Endogenous nitrosation of myosmine, present in nuts and other dietary components could constitute a significant risk factor for tumours in the upper intestinal tract such as oesophageal adenocarcinoma, which are unrelated to tobacco smoking and alcohol abuse.

Adenocarcinoma↗
PubMed2002

Ion beam treatment of titanium surfaces for enhancing deposition of hydroxyapatite from solution.

Surface coating with hydroxyapatite (HA) is a common way to improve the osseointegration of orthopaedic and dental titanium (Ti)-based materials. The main problems with current techniques are changes in composition during heating and poor adhesion to the surface. An alternative method is deposition of HA onto an activated surface out of a solution. The present work studies the surface treatment involving ion implantation of Na into Ti to induce a modification in chemistry and morphology, showing sodium titanate (Na(2)TiO(3)) incorporated within the surface layer with concentration, depth distribution, and morphology depending on the parameters of the ion implantation. Such ion-implanted Ti surfaces actively induce heterogeneous precipitation of HA from a simulated body fluid containing physiological concentrations of calcium and phosphate ions. This is compared with the activation by NaOH etching. The growth of bone forming cells on the pure Na implanted surface is oriented without an increased bone formation. Cell growth on the NaOH etched surface is reduced. After deposition of HA on both surfaces cell the growth pattern was improved.

Calcium↗
PubMed2001

The effect of a 2-h exposure to cigarette smoke on the metabolic activation of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone in A/J mice.

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a tobacco-specific nitrosamine, induces lung adenomas in A/J mice following a single intraperitoneal (i.p.) injection. However, inhalation of mainstream cigarette smoke does not induce or promote NNK-induced lung tumors in this mouse strain purported to be sensitive to chemically-induced lung tumorigenesis. The critical events for NNK-induced lung tumorigenesis in A/J mice is thought to involve O(6)-methylguanine (O(6)MeG) adduct formation, GC-->AT transitional mispairing, and activation of the K-ras proto-oncogene. The objective of this study was to test the hypothesis that a smoke-induced shift in NNK metabolism led to the observed decrease in O(6)MeG adducts in the lung and liver of A/J mice co-administered NNK with a concomitant 2-h exposure to cigarette smoke as observed in previous studies. Following 2 h nose-only exposure to mainstream cigarette smoke (600 mg total suspended particulates/m(3) of air), mice (n=12) were administered 7.5 micromol NNK (10 microCi [5-3H]NNK) by i.p. injection. A control group of 12 mice was sham-exposed to HEPA-filtered air for 2 h prior to i.p. administration of 7.5 micromol NNK (10 microCi [5-3H]NNK). Exposure to mainstream cigarette smoke had no effect on total excretion of NNK metabolites in 24 h urine; however, the metabolite pattern was significantly changed. Mice exposed to mainstream cigarette smoke excreted 25% more 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) than control mice, a statistically significant increase (P<0.0001). Cigarette smoke exposure significantly reduced alpha-hydroxylation of NNK to potential methylating species; this is based on the 15% reduction in excretion of the 4-(3-pyridyl)-4-hydroxybutanoic acid and 42% reduction in excretion of 4-(3-pyridyl)-4-oxobutanoic acid versus control. Detoxication of NNK and NNAL by pyridine-N-oxidation, and glucuronidation of NNAL were not significantly different in the two groups of mice. The observed reduction in alpha-hydroxylation of NNK to potential methylating species in mainstream cigarette smoke-exposed A/J mice provides further mechanistic support for earlier studies demonstrating that concurrent inhalation of mainstream cigarette smoke results in a significant reduction of NNK-induced O(6)MeG adduct formation in lung and liver of A/J mice compared to mice treated only with NNK.

Animals↗
PubMed2001

Effect of van der Waals interactions on the Raman modes in single walled carbon nanotubes.

We have measured the Raman spectrum of individual single walled carbon nanotubes in solution and compare it to that obtained from the same starting material where the tubes are present in ordered bundles or ropes. Interestingly, the radial mode frequencies for the tubes in solution are found to be approximately 10 cm (-1) higher than those observed for tubes in a rope, in apparent contradiction to lattice dynamics predictions. We suggest that there is no such contradiction, and propose that the upshift is due rather to a decreased energy spacing of the Van Hove singularities in isolated tubes over the spacings in a rope, thereby allowing the same laser excitation to excite different diameter tubes in these two samples.

Journal Article↗
PubMed2001

Local hyperthermia, radiation, and chemotherapy in recurrent breast cancer is feasible and effective except for inflammatory disease.

PURPOSE: To investigate the feasibility and effectiveness of radiochemothermotherapy (triple-modality therapy) in patients with inoperable recurrent breast cancer. PATIENTS AND METHODS: Patients with inoperable recurrent lesions, World Health Organization (WHO) performance status of 2 or greater, life expectancy of more than 3 months, adequate bone marrow, hepatic and renal function were eligible for this Phase I/II study. Conventionally fractionated or hyperfractionated radiotherapy (RT) was performed. Once-weekly local hyperthermia (HT) combined with chemotherapy (CT; epirubicin 20 mg/m(2), ifosfamide 1.5 g/m(2)) was applied within 30 min after RT. RESULTS: Twenty-five patients, all heavily pretreated (18/25 preirradiated), received a mean total dose of 49 Gy. The median number of HT/CT sessions was 4. Skin toxicity was low, whereas bone marrow toxicity was significant (leucopenia Grade 3/4 in 14/1 patients). The overall response rate was 80% with a complete response (CR) rate of 44%. Response rates in patients with noninflammatory disease (n = 14; CR 10 patients, partial response [PR] 3 patients) were far better than in patients with inflammatory disease (n = 11; CR 1 patient, PR 6 patients). CONCLUSIONS: In patients with recurrent breast cancer, triple-modality therapy is feasible with acceptable toxicity. High remission rates can be achieved in noninflammatory disease, however, local control is limited to a few months. Whether the addition of chemotherapy has a clear-cut advantage to radiothermotherapy alone remains an open question.

Adult↗
PubMed2001

Detection of embB codon 306 mutations in ethambutol resistant Mycobacterium tuberculosis directly from sputum samples: a low-cost, rapid approach.

Substitutions of codon 306 in the gene embB are the most common mutations found in ethambutol resistant Mycobacterium tuberculosis. The characterization of these mutations has been hampered by the need for prior cultivation of the mycobacteria, or the need for DNA sequencing, or both. Here, we describe a simple and culture-independent technique to detect embB codon 306 mutations directly from sputum samples, requiring little more than a PCR machine and a simple agarose minigel. There is no need for labelled probes or DNA sequencing. In a preliminary test of feasibility, interpretable results were obtained from 21 of 24 selected sputum samples, 12 of which were determined to contain ethambutol resistant M. tuberculosis after culture. All of six samples with embB codon 306 mutations were correctly identified. Although an exact validation of this technique is beyond the scope of this technical report, we conclude from well-known embB codon 306 mutation prevalence figures that approximately one half of EMB resistant cases could already be predicted within 2 working days, with little equipment or hands-on time needed, instead of weeks required for conventional resistance testing.

Chemistry, Clinical↗
PubMed2001

[Radiotherapy for an adenolymphoma of the parotid gland (Warthin tumor)].

BACKGROUND: With 17.6% of all primary parotid neoformations the benign Warthin's tumor (cystadenolymphoma) is the second common parotid gland tumor. Males > 50 years are affected predominantly. After surgery the recurrence rate is less than 5%. Histomorphologically the tumor is characterized by cystoid ducts lined by epithelial cells as well as lymphoid stroma. The lymphoid component has been described as radioresponsive whereas the epithelial parts are less radiosensitive. Since 1960 only one patient treated by primary radiotherapy has been published. CASE REPORT: A 77-year-old woman suffered from cystadenolymphoma (maximal diameter 7 cm). Because of its extension and the reduced performance status of the patient surgery was no option. Radiotherapy was performed with a total dose of 50 Gy. Clinically, the tumor regressed completely after 30 Gy, which was confirmed by CT at 6 weeks after completion of radiotherapy. After 6 and 12 months the patient stayed free of tumor. EPICRISIS: In our case the cystadenolymphoma was unusually large (7 cm). Radiotherapy with 50 Gy induced complete tumor regression. The good clinical response after 30 Gy suggests that the necessary dose may be lower for less extended cystadenolymphomas. CONCLUSION: We present a case of cystadenolymphoma treated by radiotherapy with 50 Gy resulting in a complete remission. Due to missing published experiences no common recommendation for the total dose can be given. In the following situations radiotherapy should be considered: 1. high surgical risk of damage to the facial nerve, 2. unfavorable cosmetic outcome after surgery, 3. inoperability for internal risks, 4. refusal of operation.

Adenolymphoma↗
PubMed2001

Haemoglobin adducts from aromatic amines in children in relation to area of residence and exposure to environmental tobacco smoke.

OBJECTIVE: The influence of area of residence on haemoglobin (Hb) adducts of 4-aminobiphenyl (4-ABP), o-, m-, p-toluidine and o-anisidine was investigated in children from three different-sized Bavarian cities - Munich, Augsburg and Eichstätt, with 1,300,000, 250,000 and 13,000 inhabitants, respectively--and was compared with that of exposure to environmental tobacco smoke (ETS). METHODS: Blood samples from Munich (n = 34) and Eichstätt (n = 64) were from children attending the Paediatric Clinic of the Technical University of Munich (TUM) or a practice in Eichstätt, respectively. Blood samples (n = 126) together with urine samples (n = 88) were collected from Augsburg children during school medical examination. Personal data including possible sources of ETS exposure were obtained at the interview. Hb adduct levels were analysed by a gas chromatographic method, using mass spectrometry with selected-ion monitoring. Urinary cotinine was determined by radioimmunoassay. RESULTS: 4-ABP Hb adduct levels in children from Munich were 1.5 and 1.2 times higher than those in children from Eichstätt and Augsburg (P < 0.001). Children from Munich also had significantly higher Hb adduct levels of monocyclic aromatic amines than did children from Eichstätt and, except for o-toluidine, children from Augsburg (P < 0.005). Compared with children from Eichstätt, children from Augsburg had higher Hb adduct levels of 4-ABP, o- and m-toluidine (P < 0.01) but not p-toluidine and o-anisidine. In a multivariate analysis, gender, age and body mass index had no consistent influence on Hb adducts. ETS exposure resulted in a slight, nonsignificant increase in 4-ABP Hb adduct levels. In contrast, adduct levels from monocyclic aromatic amines were consistently decreased in ETS-exposed children (significant for o- and m-toluidine, P<0.05). CONCLUSIONS: Hb adducts from aromatic amines in children were strongly influenced by site of residence, whereas ETS exposure did not significantly increase the adduct levels.JECT

Amines↗
PubMed2001

Use of serum creatinine to predict pathologic stage and recurrence among radical prostatectomy patients.

OBJECTIVES: To assess serum creatinine as a putative marker for staging/prognosis in localized prostate cancer. Although clinical stage, tumor grade, serum prostate-specific antigen (PSA), and tumor volume assessment by biopsy positivity are established prognostic markers in prostate cancer, the need for additional serum markers is clear. In a prior neural network analysis by our group, serum creatinine appeared to improve staging and prognosis. Even though serum creatinine is one of the most common blood tests used by practicing urologists, it has not been tested rigorously as a potential staging/prognosis marker in localized prostate cancer. METHODS: The data on 409 patients who underwent radical prostatectomy at the Walter Reed Army Medical Center between 1990 and 1996 were analyzed. Logistic regression analysis was used to evaluate the ability of serum creatinine to predict the pathologic stage. The ability of creatinine to predict PSA recurrence was also assessed using Cox regression analysis. In multivariable analyses, creatinine was assessed while simultaneously controlling for race, age, prostate weight, clinical stage, Gleason (World Health Organization) grade, prostatism history, treatment of benign prostatic hyperplasia, and pretreatment PSA level. RESULTS: Creatinine ranged from 0.1 to 2.3 mg/dL (mean and median 1.1 mg/dL). The relationship of creatinine to pathologic stage was significant (P = 0.050). As the level of creatinine increased, the proportion of patients with extraprostatic disease generally decreased. In multivariable logistic regression analysis, creatinine was not a significant predictor (P = 0.270). The relationship of the creatinine level to PSA recurrence was not significant in the univariate or multivariable analysis. CONCLUSIONS: Creatinine did not provide independent information for predicting pathologic stage or disease recurrence in patients with early prostate cancer.

Aged↗
PubMed2001

Creating a high-resolution spatial/symbolic model of the inner organs based on the Visible Human.

Computerized three-dimensional models of the human body, based on the Visible Human Project of the National Library of Medicine, so far do not reflect the rich anatomical detail of the original cross-sectional images. In this paper, a spatial/symbolic model of the inner organs is developed, which is based on more than 1000 cryosections and congruent fresh and frozen CT images of the male Visible Human. The spatial description is created using color-space segmentation, graphic modeling, and a matched volume visualization with subvoxel resolution. It is linked to a symbolic knowledge base, providing an ontology of anatomical terms. With over 650 three-dimensional anatomical constituents, this model offers an unsurpassed photorealistic presentation and level of detail. A three-dimensional atlas of anatomy and radiology based on this model is available as a PC-based program.

Anatomy, Cross-Sectional↗
PubMed2001

Differential requirement for interferon-gamma to restrict the growth of or eliminate some recently identified species of nontuberculous mycobacteria in vivo.

In recent years, a number of newly identified species of the genus Mycobacterium (M.) have been isolated from tissues of both immunocompetent and immunocompromised patients, e.g. M. celatum, M. intermedium, M. interjectum, M. bohemicum, M. conspicuum, M. confluentis, M. heidelbergense, M. lentiflavum, and M. branderi. Little is known about their in vivo virulence characteristics and the host factors predisposing to infection with these strains. In an effort to elucidate the pathogenesis of these nontuberculous mycobacterial species, BALB/c and syngeneic IFNgamma-deficient (GKO) mice were intravenously infected with 106 colony forming units of each of these species, and bacterial growth in infected organs and the development of splenomegaly and granulomatous liver lesions were examined for a period of 3 months. Based on their in vivo virulence, mycobacterial strains could be divided into three major groups: (i) Most species examined either grew progressively or persisted at plateau levels in the livers and spleens of immunocompetent mice, and their growth was increased in GKO mice. (ii) M. heidelbergense, M. intermedium and another species not officially accorded separate taxonomical status were eliminated in BALB/c mice, but persisted in GKO mice. (iii) M. confluentis, M. lentiflavum and another novel species were eradicated even in the absence of IFNgamma. Nontuberculous mycobacterial species differed widely in their capacity to induce splenomegaly and lymphadenopathy in GKO mice. In conclusion, IFNgamma is a crucial determinant of infection outcome with most, but not all opportunistic mycobacterial species.

Animals↗
PubMed2001

[Non-tubercular mycobacterial infection of the lungs due to Mycobacterium smegmatis].

Nontuberculous mycobacteriosis due to M. smegmatis is a rarity. We report on the case of a 51 year old male HIV-seronegative patient without predisposing bronchopulmonary disease, but with a state after gastrectomy and splenectomy who developed unproductive cough, night sweat and weight loss. The chest radiograph and thoracic CT showed wide-spread bilateral patchy infiltrations. Histological examination of transbronchial biopsies revealed chronic carnificating pneumonia. A perhoracic fine-needle biopsy showed caseating epitheloid cell granulomas with acid fast bacilli. These were identified as M. smegmatis by PCR with subsequent sequencing. Acid fast bacilli could not be detected microscopically neither in sputum nor in bronchial secretions, however M. smegmatis has been repeatedly detected by culture in these materials. In neither material tubercle bacilli have been detected by nucleic acid amplification (NAT) or culture. Immunologic investigations revealed a reduced number of CD4+ lymphocytes and a reduction of interferon alpha- and -gamma-synthesis by peripheral blood mononuclear cells. Treatment with Rifabutin, Ethambutol, Clarithromycin and Ofloxacin resulted in complete clinical and roentgenological resolution.

CD4-Positive T-Lymphocytes↗
PubMed2001

Impact of plasmapheresis on platelet hemostatic capacity in healthy voluntary blood donors detected by the platelet function analyzer PFA-100.

Previous flow cytometry studies showed that platelet activation may occur during cytapheresis, cardiopulmonary bypass and hemodialysis. The aim of this pilot study was to determine if the impact of plasmapheresis leads to alterations in platelet hemostatic capacity. Plasmapheresis was carried out in 30 volunteers using an Autopherese C (Baxter) and an MCS3p (Haemonetics). Blood samples were collected and analyzed immediately before and after plasmapheresis. As a result of the plasmapheresis on the Autopherese C, the mean closure time (CT) for collagen/epinephrine (Col/Epi) increased from 118.2 +/- 25.1 to 149.9 +/- 35.0 s and from 88.7 +/- 16.9 to 98.5 +/- 26.3 s for collagen/ADP (Col/ADP), respectively. Seven subjects showed impaired CTs after plasmapheresis for Col/Epi. For Col/ADP, five subjects showed impaired CTs after apheresis. Statistical analysis (McNemar test) showed a significant difference before and after apheresis for Col/Epi (P = 0.024) but not for Col/ADP (P = 0.088). Similar results were shown for plasmapheresis carried out with the MCS3p. These findings show that plasmapheresis can cause an impairment of platelet function in healthy volunteers as measured by the PFA-100, an effect of so far unknown clinical significance.

Adult↗
PubMed2001

Frequency of rpoB mutations inside and outside the cluster I region in rifampin-resistant clinical Mycobacterium tuberculosis isolates.

The prevalence of recently described mutation V176F, located in the beginning of the rpoB gene and associated with rifampin resistance and the wild-type cluster I sequence, was determined by analyzing the distribution of rpoB mutations among 80 rifampin (RIF)-resistant Mycobacterium tuberculosis strains isolated in Germany during 1997. The most frequent rpoB mutations were changes in codon 456 (52 isolates, 65%), followed by changes in codon 441 (13 isolates, 16%) and codon 451 (11 isolates, 14%). The V176F mutation was detected in one isolate of the study population and in 5 of 18 RIF-resistant strains with no cluster I mutation from six previously published studies. In three isolates, a mixture of resistant and susceptible subpopulations (heteroresistance) prohibited the detection of rpoB mutations in the initial analysis; however, in these isolates, cluster I mutations could be verified after a passage on RIF-containing medium. IS6110 DNA fingerprinting of 76 strains revealed eight clusters comprising 27 strains with identical restriction fragment length polymorphism patterns that mainly also show identical rpoB mutations and identical or similar drug resistance patterns. In conclusion, our results indicate that the V176F mutation should be included in molecular tests for prediction of RIF resistance in M. tuberculosis. We further demonstrated that heteroresistance caused by a mixture of mycobacterial subpopulations with different susceptibilities to RIF may influence the sensitivity of molecular tests for detection of resistance.

Adult↗