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M Schaefer

Publications and source records attributed to M Schaefer.

157 records · Page 9Linked to original sources
PubMedDate not supplied

Polymeric conjugates of Gd(3+)-diethylenetriaminepentaacetic acid and dextran. 2. Influence of spacer arm length and conjugate molecular mass on the paramagnetic properties and some biological parameters.

Macromolecular conjugates of dextran 40 (Mn = 38 kg/mol, Mw = 43 kg/mol) and diethylenetriaminepentaacetic acid (DTPA), capable of complexing Gd3+, were synthesized in order to obtain contrast agents for nuclear magnetic resonance imaging, with long intravascular persistence. As already reported, relaxivity of these macromolecular complexes was greater than that of molecular complexes (2-2.5 times). On the other hand, as relaxivity of paramagnetic agents partially depends on their rotation speed, the influence of the length of the spacer arm inserted between DTPA and dextran was investigated. Various conjugates with spacer arms comprised of methylenic chains (-(CH2)n-) with varying lengths (2 < or = n < or = 6) were prepared. The result was that, whatever the distance between DTPA and dextran, all of the Gd(3+)-complexed polymeric conjugates with similar DTPA content (0.6-0.8 mmol/g) exhibited, at 20 MHz, about the same relaxivity values. On the other hand, in the same way, no significant effect of the molecular masses (Mn between 166 and 224 kg/mol and Mw between 332 and 865 kg/mol) of the polymeric conjugates on relaxivity were observed. Toxicity studies carried out on mice, showed very similar LD50 values whatever the spacer arm and molecular mass of the macromolecular conjugates. Finally the urinary excretion studied on rats (after 4 h) and on rabbits (after 24 h) was relatively low (15-20% of the administered dose), and, as expected, the lower values were obtained with the higher molecular mass conjugates.

Animals↗
PubMedDate not supplied

Capacity of purified Lyt-2+ T cells to mount primary proliferative and cytotoxic responses to Ia- tumour cells.

Allogeneic gene products of the major histocompatibility complex, the HLA complex in man and the H-2 complex in mice, induce T lymphocytes to exert powerful mixed lymphocyte reactions (MLR) and cell-mediated lympholysis (CML). In mice, the subset of T cells carrying the L3T4 surface antigen but lacking the Lyt-2 antigen responds predominantly to H-2 class II (Ia) differences whereas the L3T4- Lyt-2+ subset reacts to class I (K/D) differences. For primary responses the stimulus for MLR and CML appears to be controlled by Ia+ cells of the macrophage/dendritic cell lineages, for both L3T4+ and Lyt-2+ cells. The finding that Ia+ cells are required for responses involving Lyt-2+ cells has been taken to imply that triggering of these cells is controlled by Ia-restricted L3T4+ cells. Lyt-2+ cells have thus come to be regarded as crippled cells which are heavily dependent on 'help' from other T cells. This well-entrenched view is challenged by evidence presented here that purified Lyt-2+ cells can give high primary responses to certain Ia- tumour cells in vitro.

Animals↗
PubMedDate not supplied

[Doppler ultrasound examination of fetal umbilical arteries of the intra-abdominal segment in normal singleton pregnancies].

BACKGROUND: In the management of high risk pregnancies, blood flow measurements in the umbilical arteries (Aa. umb) have reduced perinatal morbidity and mortality. No consensus has been reached about the optimal location of measurements along the umbilical cord. The present study analyses the blood flow in both umbilical arteries where they pass by the fetal bladder. PATIENTS AND METHODS: In 48 normal pregnancies, Doppler examinations were used to measure the pulsatility indices (PI). From the 20th week of pregnancy onward, the PI were measured once every four weeks in the intraabdominal segments of the right and the left Aa. umb. lateral to the fetal bladder. Measurements were also done in a free loop and at the placental insertion. RESULTS: For all locations, normal ranges were calculated. The PI at all four sites decreased as the pregnancies were approaching term. In the III. trimester, the standard deviations of PI were smaller than in the II. trimester. The PI at the intraabdominal segment of the right and the left umbilical arteries turned out to be similar to each other and exceeded the values measured at the free loop and at the placental insertion respectively. CONCLUSION: The intraabdominal segments of the umbilical arteries were defined as a new location for PI measurements. When adopting a fixed place of measurement, it is likely that the reproducibility of PI measurements will be increased. DISCUSSION: The higher PI at the intraabdominal segment of the umbilical arteries are caused by the more central location compared to the placental insertion.

Blood Flow Velocity↗
PubMedDate not supplied

[Current diagnosis and therapy of undescended testis].

Although the etiology of maldescended testes is multifactorial, dysfunction of hypothalamic-pituitary-gonadal axis should be considered as the most important factor. The hormonal treatment with Gn-RH on its own or followed by hCG can provoke testicular descent and should be applied at 10th month of life. Failure, partial or transient success needs orchidopexy within the first two years of life to prevent infertility. If a concomitant hernia or a true ectopia is encountered, if patients are seen at an adolescent age and if the testes are truly cryptorchid, surgery is the treatment of choice.

Child↗
PubMedDate not supplied

Bioavailability of clobetasol propionate-quantification of drug concentrations in the stratum corneum by dermatopharmacokinetics using tape stripping.

The concentration of clobetasol propionate in the stratum corneum after application of three different formulations was determined, quantifying the influence of the formulations on the bioavailability of the drug. The stratum corneum was sampled by tape stripping. The concentrations of clobetasol propionate were determined quantitatively by HPLC. After application of Clobetasol Propionate Cream USP, 0.05%, and Temovate Cream, 0.05%, identical amounts of the drug were found in the stratum corneum, whereas after application of Temovate epsilon Emollient, 0.05%, the quantity was clearly decreased. From results obtained measuring the drug concentration in the adjacent sites of the skin where the creams had not been applied, it became clear that clobetasol propionate in Temovate epsilon Emollient, migrated to a large extent in the lateral direction. This explains the lower concentration measured for this formulation in the skin areas where the cream had been applied. In general, a lateral distribution of the applied drug must be taken into account when positioning the application areas on the forearm.

Administration, Cutaneous↗
PubMedDate not supplied

Lithium treatment of depressed and nondepressed alcoholics.

We assessed the efficacy of lithium carbonate in the treatment of 457 male alcoholics in a double-blind, placebo-controlled Department of Veterans Affairs Cooperative Study. Alcoholics either without depression or with a history of major depression, current major depression, or dysthymic disorder were studied. Two hundred eighty-six alcoholics without depression and 171 alcoholics with depression began the 52-week outpatient study; 172 alcoholics (60.1%) without depression and 108 alcoholics (63.2%) with depression completed the study. Among both all alcoholics who began the study and a subgroup who completed the study, no significant differences between alcoholics who took lithium and those who took placebo were found for the following outcome measures:number of alcoholics abstinent, number of days of drinking, number of alcohol-related hospitalizations, changes in rating of severity of alcoholism, and change in severity of depression. Similarly, no significant differences were found when only the 82 alcoholics compliant in taking lithium and the 89 alcoholics compliant in taking placebo were considered. In our study, lithium treatment did not affect the course of alcoholism in either depressed or nondepressed alcoholics.

Adult↗
PubMedDate not supplied

Multiple bilateral sialoliths of the submandibular ducts.

A patient with a history of 20 years of intermittent pain and swelling of the floor of the mouth was diagnosed with bilateral multiple sialoliths of the submandibular ducts. Subsequent to the excision of all the sialoliths, the patient was asymptomatic. She will be observed periodically.

Female↗