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Biomedical subjects

R Lambrecht

Publications and source records attributed to R Lambrecht.

At least 19 recordsLinked to original sources
PubMed2001

There is no influence of a temperature rise on in vivo adsorption of UV filters into the stratum corneum.

Temperature influences the stratum corneum adsorption of several topically applied compounds. This study was designed to evaluate the influence of the temperature on the stratum corneum adsorption of 3 UV filters. The UV filters were solubilized in two vehicles, an emulsion gel and petroleum jelly and applied at respectively, 31 and 40 degrees C during 30 min. In vivo stratum corneum UV filter content was measured using the tape stripping method. Similar amounts of UV filter were detected in the stratum corneum when comparing applications at the different temperatures. Application of the UV filters in the emulsion gel resulted in higher stratum corneum UV filter concentrations compared with application in the petroleum jelly. The application temperature did not influence the stratum corneum adsorption of the tested UV filters while the nature of the vehicle significantly influenced the amount of UV filters recovered from the stratum corneum.

Adult↗
PubMed2001

A comparative study of the effects on the skin of a classical bar soap and a syndet cleansing bar in normal use conditions and in the soap chamber test.

BACKGROUND/AIMS: The skin irritation potential of a body cleansing product is often compared under exaggerated test conditions, although the product is intended to be used at home with repetitive and brief contact with the skin. The aim of this study was to determine how much patch testing is predictive of the clinical, sub-clinical and subjective cutaneous effects of products used at home by consumers for their normal hygienic cleansing. METHODS: A double-blind comparative study of the normal use of an alkaline soap bar and a syndet at home during 10 consecutive weeks was performed on two identical groups of 25 healthy female subjects. The eventual skin changes observed at different anatomical skin sites were evaluated by clinical visual examination and by bioengineering measurements before the start of the study and then every 2 weeks. The objective measurements were compared with the subject's perceptions of dryness, tightness and product irritancy during the testing. RESULTS: The bioengineering measurements did not show any significant changes on all the anatomical skin sites, except for a small increase in skin pH with the classical soap bar. However, a trend appeared, showing that the alkaline soap bar is perceived by the subjects themselves as more of an irritant than the syndet bar. In the soap chamber test, the bar soap showed a significantly higher irritancy than the syndet bar. CONCLUSION: This study showed that cutaneous irritation induced by cleansing products in patch testing is not necessarily predictive of the irritation likely to occur in normal use conditions. Finally, a clear relationship could be demonstrated between the results of the soap chamber test and the consumer perception of both cleansing bars.

Adult↗
PubMed1998

In vivo evaluation of a lead-labeled monoclonal antibody using the DOTA ligand.

The aim of this study was to assess the utility of a radioimmunoconjugate containing a lead radionuclide for therapy and scintigraphy applications. The radioimmunoconjugate evaluated consisted of a bifunctional DOTA ligand and monoclonal antibody (MAb) B72.3 using athymic mice bearing LS-174T tumors, human colon carcinoma xenografts. In the studies reported here, the lead-203-DOTA complex itself was first demonstrated to have in vivo stability. MAb B72.3 was then conjugated with the DOTA ligand and labeled with 203Pb, and the immunoreactivity of B72.3 was maintained. The localization of the radioimmunoconjugate to tumor tissue and other select organs paralleled that of DOTA-125I-B72.3, suggesting a similar metabolic pattern of the two radioimmunoconjugates. Thus, the DOTA-metal complex does not alter the behavior of the radioimmunoconjugate. Tumor localization of the 203Pb-DOTA-B72.3 conjugate was demonstrated with biodistribution studies as well as immunoscintigraphy studies. Such data highlight the stability of a lead radionuclide in the DOTA ligand. The suitability of this chelation chemistry for labeling radioimmunoconjugates with a lead radionuclide now makes its application in nuclear medicine a feasible proposition.

Animals↗
PubMed1996

Localization of temporal lobe epileptic foci with iodine-123 iododexetimide cholinergic neuroreceptor single-photon emission computed tomography.

There is evidence suggesting that muscarinic cholinergic neuroreceptors (mChR) are reduced at seizure foci. Iodine-123 (I-123) iododexetimide (IDEX) single-photon emission computed tomography (SPECT) permits in vivo imaging of mChR. We assessed 23 patients with temporal lobe epilepsy (TLE) undergoing preoperative assessment. Regions of interest were placed over the amygdala, hippocampus, and lateral temporal cortex on IDEX SPECT images. Eighteen patients had unilateral TLE. In these, IDEX binding in the ipsilateral hippocampal region was reduced by 19.1 +/- 12%. This was significantly greater than blood flow asymmetry (p < 0.02 by Wilcoxon's signed-rank test). Changes were less marked in the amygdala (11.3 +/- 6.4%) and lateral cortex (7.6 +/- 12.1%). Blinded visual analysis gave correct localization in 14 (78%) patients, and hexamethylpropylenamine oxide (HMPAO) SPECT gave correct localization in 50%. MRI revealed hippocampal sclerosis in 13 (72%) patients and was normal in 5 patients. Of the latter group, four were correctly localized by IDEX. This study confirms that mChR receptors are altered in medial temporal lobe structures in TLE. IDEX SPECT appears to be superior to interictal HMPAO SPECT and complimentary to MRI for seizure focus localization.

Adult↗
PubMed1992

A facile purification procedure of phospholipase D from cabbage and its characterization.

Phospholipase D (PLD), an enzyme predestined for the preparation of new phospholipids, was isolated from cabbage and purified in a highly efficient way by using a combination of hydrophobic chromatography and a specific calcium effect. In the presence of calcium ions (50mM), PLD is bound from the crude enzyme solution to Octyl-Sepharose and subsequently selectively eluted by removing the calcium ions. The obtained enzyme is electrophoretically pure (95%), its molecular mass and isoelectric point were determined to be 87,000 Da and 4.7, respectively. The purified enzyme was kinetically characterized by use of mixed phosphatidylcholine-SDS micelles as well as the short-chain lecithins 1,2-dihexanoyl- and 1,2-diheptanoyl-sn-glycero-3-phosphocholine as substrates. A hyperbolic upsilon/[S]-characteristic was obtained for the mixed micellar system, whereas the upsilon/[S] curves of the short-chain lecithins reflect the dependence of velocity on the physical state of the substrate. A small velocity increase was observed up to a critical substrate concentration near the critical micelle concentration, from where the velocity increases hyperbolically.

Brassica↗
PubMed1991

Quantitative measurement of monoclonal antibody distribution and blood flow using positron emission tomography and 124iodine in patients with breast cancer.

The uptake and in vivo quantitation of monoclonal antibodies (MAbs) has been measured non-invasively using positron emission tomography (PET) and 124iodine in 9 patients with breast ductal carcinoma. Blood-flow measurements were also made using 15oxygen-labelled water and PET to evaluate antibody delivery; 7 patients were studied with HMFGI antibody and 2 patients with a non-specific antibody. Tumour uptake ranged from 2-7.7 x 10(-3)% of injected dose per gram of tissue. Values for normal tissues including liver, lung and bone were also obtained. In 2 out of 7 patients studied with the specific antibody, uptake was greater than that seen with the non-specific antibody. There was no correlation between antibody uptake and blood flow. This report exemplifies the potential of PET for the non-invasive and accurate quantitative assessment of targeted antibody which is a prerequisite to therapy.

Adult↗
PubMed1989

Penetrating chest injuries.

The purpose of this paper is to review our experience in the management of penetrating chest injuries and their outcome in spite of the shortage of equipment for thoracic surgery at the Gonder Hospital. The study was based on prospective analysis of 32 cases treated at this hospital between February 1987 and February 1988. About 30% of our cases has associated injuries to other organs. Simple pleural space drainage was done in 19 cases. Only 4 of the patients required immediate or delayed thoracotomy while 3 other cases required laparotomy. Complications occurred in 8 patients, of whom 6 died. In 6 cases only conservative treatment was indicated. About 80% of our patients with penetrating chest chest injuries were treated successfully with no, or only minimal, residual defects. Availability of of simple and effective materials in rural hospitals is recommended.

Adolescent↗
PubMed1988

[Clinical, immunologic and therapeutic aspects of endangiitis obliterans].

In the period of 1975-1983 twenty-three patients with thromboangiitis obliterans were examined at the Surgical Clinic of the Medical Academy of Magdeburg. The diagnosis was established clinically, angiographically histologically and immunologically. In 7 out of 12 patients histology revealed inflammatory vascular alterations including lymphocyte infiltrates throughout the entire vessel wall and also in the perivascular area. Immunohistology showed in 10 out of 15 patients segmental granular fluorescence identifiable as deposits of IgM and IgG. In 6 cases a complement formation was found. The endangiitis group revealed more frequent and increased immune complexes concentrations. Circulating immune complexes were established by phase-locked radio-immunoassay. The therapy is depended on the localization of the obliteration and can be a lumbar sympathectomy or a vascular reconstruction.

Adult↗
PubMed1988

Immobilization of acetylcoenzyme A synthetase and the preparation of an enzyme reactor for the synthesis of [11C]acetylcoenzyme A.

The enzyme acetylcoenzyme A synthetase (acetate-CoA ligase (AMP forming), EC 6.2.1.1) from Saccharomyces cerevisiae (baker's yeast) is used for the synthesis of 1 mumol [11C]acetylcoenzyme A. (CoA-[11C]Ac). A screening of the immobilization of the enzyme on differently derivatized controlled pore glass beads (50 nm pore size and 125-180 micron particle size) was performed. Several silanes, spacer arms and terminal reactive groups were tested. The immobilized enzyme was subjected to storage stability tests. From these experiments, the method of choice was selected: immobilization on CNBr-activated controlled pore glass. The immobilized parameters were optimized further to improve the activity of the enzyme-loaded glass beads. The latter were packed in a glass column. The kinetic properties of the column were investigated and optimized to obtain an almost complete conversion of 1 mumol acetate into acetylcoenzyme A (CoA-Ac) within a few minutes. This is realized with an enzyme reactor (13.0 x 0.5 cm) containing 6.12 U active acetylcoenzyme A synthetase immobilized onto 1 g controlled pore glass.

Acetate-CoA Ligase↗
PubMed1987

Evidence for cytochrome P450-mediated oxidation of uroporphyrinogen by cell-free liver extracts from chick embryos treated with 3-methylcholanthrene.

Cell-free preparations from liver of chick embryo treated with 3-methylcholanthrene catalyzed oxidation of uroporphyrinogen I in the presence of NADPH and 3,4,3',4'-tetrachlorobiphenyl. Extracts of untreated embryo liver or liver from embryo treated with glutethimide, a phenobarbital-like inducer of cytochrome P450 in this system, did not catalyse the oxidation. Direct involvement of cytochrome P450 was demonstrated by inhibition of the oxidation by CO, piperonyl butoxide and specific antisera to the methylcholanthrene-induced cytochrome P450. 2,4,2',4'-tetrachlorobiphenyl was inactive in the oxidation. These results may explain the role of induced cytochrome P450 in experimental uroporphyria. The oxidation may be useful as a simple assay for reactive O2 species.

Animals↗
PubMed1986

[Recording of cell-mediated immunity in patients with gliomatous brain tumors].

The cell-mediated immunity state by detecting lymphokine in the macrophage electrophoresis mobility test (MEM-test) was supervised in 9 patients with gliomatous cerebral tumors and 12 normal subjects. A positive lymphokine proof was provable by application of 100 micrograms antigen in 8 of 9 patients of the tumor group, however, in the control group in 1 of 12 probands. The MEM-test is a practical improvement of the immunodiagnosis especially for tumors of the nervous system despite the high technical and temporal expense.

Adult↗
PubMed1986

The in vitro radiobiology of astatine-211 decay.

Chinese hamster V79 cells in culture were exposed to astatine-211, an alpha-particle-emitting radiohalogen. The dose-log survival response was linear with no detectable shoulder. Cells in monolayers had a D0 of 1.0 microCi/ml. Suspended cells had a D0 of 0.60 microCi/ml with a cellular uptake of 2.5 fCi/cell; this is equal to approximately 1.5 alpha-particle traversals per cell nucleus. The frequencies of chromosome and chromatid breaks were linear with dose, but the number declined rapidly with time. These data are discussed in relation to published alpha-particle beam studies and the potential use of 211At in radionuclide therapy.

Alpha Particles↗
PubMed1985

[Comparative studies of the determination of T lymphocytes in human peripheral blood].

Different methods for determination of T-lymphocytes in human peripheral blood were compared: rosetting with sheep erythrocytes (SRBC), AET-treated SRBC, immunofluorescence using a monoclonal antibody against T cells (BL-T2), complement dependent cytolysis with polyclonal antisera against thymocytes, cytochemical demonstration of unspecific acid alpha-naphthyl-acetate esterase (ANAE), and electrophoretic mobility using a cell electrophoresis system (PARMOQUANT 2). Depending on the method, mean values between 70 and 79% T cells among separated mononuclear cells (MNC) were found. All paired observations were subjected to statistical analysis using rank correlation and U-test. From this analysis it is concluded that rosetting with SRBC, immunofluorescence using the monoclonal T-cell antibody and cytochemical reactivity for ANAE are favored methods for determining the T cell content of human MNC. However, the monoclonal antibody BL-T2 and the ANAE are not generally applicable because both markers were also found on malignant B-lymphocytes (B-CLL).

Adult↗