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Biomedical subjects

A Lemke

Publications and source records attributed to A Lemke.

12 recordsLinked to original sources
PubMed2006

HPLC detection of miltefosine using an evaporative light scattering detector.

Miltefosine has recently been introduced as leishmanicidal drug for oral administration (Impavido). Previous communications report about the use of liquid chromatography coupled with mass spectrometry detection to detect miltefosine in pharmaceutical preparations and biological fluids. We report about a new method to detect miltefosine using an evaporative light scattering detector (ELSD). The absolute recovery of the analyte was greater than 98.0%. The limit of quantification for miltefosine in plasma at a signal-to-noise ratio of 7.3 was 0.34 microg/ml. The precision of the assay yielded coefficients of variation ranging from 1.8 to 4.5% and an accuracy of 97-107%. Our method advances the qualitative and quantitative detection of miltefosine by combining rapid and efficient solid phase extraction and analysis with an evaporative light-scattering detector.

Antiprotozoal Agents↗
PubMed2005

Amphotericin B.

Invasive fungal infections are a major cause of morbidity and mortality in immunodeficient individuals (such as AIDS patients) and in transplant recipients or tumor patients undergoing immunosuppressive chemotherapy. Amphotericin B is one of the oldest, yet most efficient antimycotic agents. However, its usefulness is limited due to dose-dependent side-effects, notably nephrotoxicity. In order to improve its safety margin, new pharmaceutical formulations of amphotericin B have been designed especially to reduce its detrimental effects on the kidneys. Since the 1980s, a wide variety of new amphotericin B formulations have been brought forward for clinical testing, many of which were approved and reached market value in the 1990s. This review describes and discusses the molecular genetics, pharmacological, toxicological, and clinical aspects of amphotericin B itself and many of its innovative formulations.

Amphotericin B↗
PubMed2005

The impact of nanobiotechnology on the development of new drug delivery systems.

Nanotechnology, or systems/devices manufactured at the molecular level, is a multidisciplinary scientific field undergoing explosive development. A part of this field is the development of nanoscaled drug delivery devices. Nanoparticles have been developed as an important strategy to deliver conventional drugs, recombinant proteins, vaccines and more recently nucleotides. Nanoparticles and other colloidal drug delivery systems modify the kinetics, body distribution and drug release of an associated drug. Other effects are tissue or cell specific targeting of drugs and the reduction of unwanted side effects by a controlled release. Therefore nanoparticles in the pharmaceutical biotechnology sector improve the therapeutic index and provide solutions for future delivery problems for new classes of so called biotech drugs including recombinant proteins and oligonucleotides. This review discusses nanoparticular drug carrier systems with the exception of liposomes used today, and what the potential and limitations of nanoparticles in the field of pharmaceutical biotechnology are.

Animals↗
PubMed2000

Assessment of the vascularization of neuroendocrine tumors by stimulated acoustic emission of SH U 508A ultrasound contrast agent and color or power Doppler sonography.

RATIONALE AND OBJECTIVES: To assess the vascularization of neuroendocrine tumors by stimulated acoustic emission (SAE) of SH U 508A during the blood pool phase in comparison with contrast-enhanced Doppler sonography. METHODS: Thirty-six patients with neuroendocrine tumors received contrast-enhanced Doppler sonography and 21, an additional SAE. To classify tumor perfusion on Doppler sonography, a 4-step rating score was introduced: (1) no vessels (hypoperfusion); (2) one feeding or central vessel (hypoperfusion); (3) some vessels (hyperperfusion); and (4) disseminated vessels (hyperperfusion). In 36 patients, 1 pancreatic primary tumor, 33 liver metastases, 1 splenic metastasis, and 1 lymph node metastasis were examined. Results were correlated with biphasic spiral CT (n = 35) and angiography (n = 2). RESULTS: Arterial-phase CT and digital subtraction angiography revealed 18 hyper- and 18 hypoperfused lesions. Contrast-enhanced Doppler correctly classified 15 of 18 patients (83%) with hyperperfused lesions as well as 16 of 18 (89%) hypoperfused tumors by applying the rating score. SAE correctly identified 4 of 9 hyperperfused lesions (44%), 2 were isoperfused compared with normal liver tissue (22%), and 3 were hypoperfused (33%). Of 12 hypoperfused lesions, 11 were classified correctly (92%), and 1 showed isoperfusion. Hence, the positive and negative predictive values for SAE were 80% and 69%, respectively. For contrast-enhanced Doppler sonography, positive and negative predictive values were 88% and 84%, respectively. CONCLUSIONS: Blood pool SAE failed to determine subtle tumor perfusion correctly. The rating score for contrast-enhanced Doppler sonography characterized tumor perfusion with high accuracy. The use of a contrast agent significantly improved perfusion characterization.

Angiography, Digital Subtraction↗
PubMed2000

Tetrabromo(2,6-dimethylpyridine-N)titanium(IV), a twinned crystal structure

The reaction of 2,6-dimethylpyridine with TiBr(4) affords the title compound, [TiBr(4)(C(7)H(9)N)], which is the first example of a neutral TiBr(4)L complex (L is a singly bonded ligand). The environment around the Ti atom can be described as a somewhat distorted trigonal bipyramid, with the nitrogen base occupying an equatorial position. The crystal was a non-merohedral twin.

Journal Article↗
PubMed1999

[MRI in the diagnosis and differential diagnosis of radiocarpal diseases and injuries].

Advances in MRI technology have greatly improved visualization of the radio-carpal region. With todays high-resolution imaging, even very small anatomic structures like the triangular fibrocartilage may be seen. Established indications include the osteonecroses (scaphoid and lunate); however, MR images always should be evaluated in conjunction with plain radiographs. By delineating bone marrow edema, MRI is well suited for the detection of microfractures. Visualization of small soft tissue tumors, soft tissue extension of bone tumors and for staging of tumors in general may also be regarded as indications generally agreed upon. Promising indications include pathology of ligaments and similar structures.

Arthritis, Rheumatoid↗
PubMed1996

[MRT of the eye: the normal anatomy and detection of the smallest lesions with a high-resolution surface coil].

PURPOSE: A new, high-resolution surface coil for MRI of the eye was evaluated with regard to practicability, image quality and sensitivity for small lesions. MATERIAL AND METHODS: 48 patients in whom a space-occupying lesion of the eye or orbit was suspected were examined (1.5 T tomograph, 5 cm surface coil, T1- and T2-weighted spin-echo sequences, the former before and after i.v. gadolinium DTPA). RESULTS: 45/48 patients tolerated MR with the high-resolution surface coil. No adverse effects were experienced by the patients. In 11/48 patients a space occupying lesion of the eye was detected (melanoma, 5; metastases, 2; haemorrhage, 1; malformation, hamartoma and scarring after melanoma, one each). The smallest detectable lesion had a thickness of < 1 mm. CONCLUSION: First experiences with the high-resolution surface coil indicate that this device is suited for detection of very small lesions of the eye.

Adolescent↗
PubMed1995

Telemedicine in rural areas. Experience with medical desktop-conferencing via satellite.

Cooperation between physicians in hospitals in rural areas can be assisted by desktop-conferencing using a satellite link. For six weeks, medical desktop-conferencing was tested during daily clinical conferences between the Virchow-Klinikum, Berlin, and the Medical Academy, Wroclaw. The communications link was provided by the German Telekom satellite system MCS, which allowed temporary connections to be established on demand by manual dialling. Standard hardware and software were used for videoconferencing, as well as software for medical communication developed in the BERMED project. Digital data, such as computed tomography or magnetic resonance images, were transmitted by a digital data channel in parallel to the transmission of analogue video and audio signals. For conferences involving large groups of people, hardware modifications were required. These included the installation of a video projector, adaptation of the audio system with improved echo cancellation, and installation of extra microphones. Learning to use an unfamiliar communication medium proved to be uncomplicated for the participating physicians.

Germany↗
PubMed1994

Delta F508 genotype does not predict disease severity in an ethnically diverse cystic fibrosis population.

OBJECTIVE: As part of a study to determine population-based frequencies of CFTR mutations in an ethnically diverse, midwestern cystic fibrosis (CF) population, clinical histories were studied in 119 CF patients. METHODOLOGY: We sought to examine the association between genotype as characterized by the delta F508 and 11 other commonly occurring mutations and clinical parameters including age at diagnosis, clinical presentation, sweat chloride level, chest roentgenogram score, clinical scores, pulmonary function test results, percent weight for height, and presence of associated CF complications. RESULTS: Age at diagnosis of CF was significantly associated with homozygosity for delta F508 (mean age at diagnosis +/- SE: 1.7 +/- 0.3 years for delta F508/delta F508 vs 3.9 +/- 0.9 years for delta F508/other and other/other; P = .03). No other age-adjusted clinical parameter was significantly associated with delta F508 or any other genotype. CONCLUSION: These data suggest that in this sample of CF patients, delta F508 genotype is not predictive of disease severity. The lack of association between disease severity and genotype in this ethnically diverse sample may reflect the presence of more severe undetected mutations in our sample, or the effects of modifying genes at other, non-CF loci.

Adolescent↗
PubMed1992

Ethnic heterogeneity and cystic fibrosis transmembrane regulator (CFTR) mutation frequencies in Chicago-area CF families.

The identification of a common mutation, delta F508, in the CFTR gene allowed, for the first time, the detection of cystic fibrosis (CF) carriers in the general population. Further genetic studies revealed > 100 additional disease-causing mutations in this gene, few of which occur on > 1% of CF chromosomes in any ethnic group. Prior to establishing counseling guidelines and carrier risk assessments, we sought to establish the frequencies of the CFTR mutations that are present in CF families living in the Chicago area, a region notable for its ethnic heterogeneity. Our sample included 283 unrelated CF carriers, with the following ethnic composition: 78% non-Ashkenazi Caucasians, 5% Ashkenazi, 9% African-American, 3% Mexican, 0.3% Native American, and 5% mixed ancestry. When a panel of 10 mutations (delta F508, delta I507, G542X, G551D, R553X, S549N, R1162X, W1282X, N1303K, and 1717-1G-->A) was used, detection rates ranged from 75% in non-Ashkenazi Caucasians to 40% in African-Americans. These data suggest that the goal of screening for 90%-95% of CF mutations may be unrealistic in this and other, similar U.S. populations.

Base Sequence↗
PubMed1990

Psychological factors that predict AIDS high-risk versus AIDS precautionary behavior.

Men (N = 526) who patronized gay bars in three cities completed measures of sexual behavior covering the previous 3 months and psychological measures theoretically pertinent to AIDS risk. Thirty-seven percent of the sample reported engaging in unprotected anal intercourse, the behavior most strongly associated with transmission of human immunodeficiency virus (HIV) infection. Perceived peer norms concerning the acceptability of safer sex practices, AIDS health locus of control scores, risk behavior knowledge, age, and accuracy of personal risk estimation, but not personal HIV serostatus knowledge, were associated with high-risk and precaution-taking behavior.

Acquired Immunodeficiency Syndrome↗