Prolonged rat allograft survival induced by temporary elimination of α/β T cells with monoclonal antibody

Abstract We tested the ability of lewis (LEW; RT-1¹) recipients to reject DA (RT-1^av1) cardiac allografts following the selective elimination of α/β T cells with the mouse monoclonal antibody R73. One group of adult rats (6 weeks old) received 1000 μ R73 i.p. on days 2 and 1 before transplantation, and 100 pg R73 every third day after transplantation up to day 18. Prolonged cardiac graft survival was noted (30, 30, 32, 51, 62, 108, > 500, > 500, > 500 days). Untreated controls ( n = 10) rejected their grafts within 7 ± 1 days. R73 therapy induced a dramatic decrease in α/β T cells from 69% before treatment to 5% within the first 5 days, followed by an increase to 64% by day 8. The T cell increase was paralleled by the appearance of anti-mouse antibody. A second group of adult rats (10 weeks old) received the same treatment. These "older" recipients rejected their grafts within 20 ± 5 days. Chronic R73 therapy from birth until the day of transplantation (100 μ R73 i.p. twice a week) resulted in graft survival of 37 ± 9 days in eight animals. Two rats had a graft survival of more than 200 days. When chronic R73 therapy was continued to day 70 after transplantation, DA hearts were accepted well in all animals for more than 100 days. α/β T cells were virtually absent throughout the whole time of treatment. Antibodies against R73 were not detected. We concluded that selective elimination of a/B T cells has a strong effect on allograft survival.     

Functional magnetic resonance imaging with intermolecular double-quantum coherences at 3 T.

Functional magnetic resonance imaging (fMRI) based on the selection of intermolecular double-quantum coherences (iDQC) was performed with a standard birdcage coil at 3 T in a group of normal human volunteers. Suppression of spurious signal contributions from unwanted coherence-transfer pathways was achieved by combining a two-step phase cycle and a long repetition time of 5 s. A gradient-recalled echo iDQC sequence (echo time, T(E) = 80 ms) yielded robust activation with a visual paradigm. Maximum z-scores were about half of those observed with conventional blood-oxygen level dependent fMRI, whereas the functional signal change increased by more than a factor of 5. No activation was obtained with a spin-echo iDQC sequence (T(E) = 160 ms), in which dephasing accumulated during the evolution period was fully rephased by an appropriate delay time. It is hypothesized that substantial inherent diffusion weighting of the iDQC technique efficiently suppresses intravascular contributions to the functional contrast. A consistent quantitative explanation of the observed amount of signal change currently remains speculative.     

Efficiency of flow-driven adiabatic spin inversion under realistic experimental conditions: a computer simulation.

Continuous arterial spin labeling (CASL) using adiabatic inversion is a widely used approach for perfusion imaging. For the quantification of perfusion, a reliable determination of the labeling efficiency is required. A numerical method for predicting the labeling efficiency in CASL experiments under various experimental conditions, including spin relaxation, is demonstrated. The approach is especially useful in the case of labeling at the carotid artery with a surface coil, as consideration of the experimental or theoretical profile of the B(1) field is straightforward. Other effects that are also accounted for include deviations from a constant labeling gradient, and variations in the blood flow velocity due to the cardiac cycle. Assuming relevant experimental and physiological conditions, maximum inversion efficiencies of about 85% can be obtained.     

Down syndrome and male fertility: PCR-derived fingerprinting, serological and andrological investigations

Down syndrome, the most common birth defect causing mental retardation, is characterized by a specific phenotype including subfertility or sterility and hypogonadism in males. In contrast, several females with Down syndrome have borne offspring. Here, a male with trisomy 21 fathering an infant is described. This observation is verified by serological markers, DNA fingerprinting using different DNA micro-or minisatellites and andrological investigations.     

Angiographic anatomy of hearts with one ventricular chamber: the true single ventricle

Fifteen patients with an isolated ventricular chamber were studied using angiography. These patients constitute 7% of the 218 patients with single ventricle who were examined at our institution over a 10-year period. The atrial situs was solitus in 6 and isomeric in 9. The ventricular chamber showed 3 varieties based on trabecular pattern: right type, mixed and indeterminate. The atrioventricular (AV) connection was through 2 valves in 4 hearts, through a common AV valve in 8 and through a single valve in 3. The morphologic features of the ventricular chamber and the AV valves are considered the most important factors for planning surgical management.     

Organochlorine pesticide accumulation and genotoxicity in Mexican free-tailed bats from Oklahoma and New Mexico

The summer population of Mexican free-tailed bats (Tadarida brasiliensis) at Carlsbad Caverns, New Mexico, declined from an estimated 8.7 million in 1936 to 200,000 in 1974; thereafter, it increased to approximately 700,000 in 1991. This decline has been attributed primarily to organochlorine (OC) pesticide contamination and habitat disturbance. Similar declines have been observed in other populations of this species. This study examined the potential genotoxic effects of OC pesticide contamination on two populations of T. brasiliensis. Pesticide accumulation, frequencies of chromosomal aberrancy, and nuclear DNA content variation in spleen and testicular tissues were examined in specimens collected from Carlsbad Caverns and Vickery Cave, a maternity colony in northwestern Oklahoma, during the summers of 1990 and 1991. Pesticide residues in brain and carcass tissues were identified and quantified by electron capture gas chromatography. Genotoxicity was examined with the standard bone marrow chromosomal aberration assay and flow cytometry. Statistical relationships among pesticide content, observed chromosomal aberrancy, and nuclear DNA content variation were examined. Both populations demonstrated significant levels of DDE contamination; however, the Carlsbad Caverns population showed consistently higher pesticide loads. Males also demonstrated higher levels than females. No statistical differences in chromosomal aberrancy or nuclear DNA content variation were observed among sexes, sites, or collected periods. Positive correlations were detected between brain and carcass DDE concentrations for all bats examined. A significant negative relationship was found between brain DDE concentration and coefficients of variation in spleen DNA content only for males.     

Wert und Gefahren der allgemeinen Thromboseprophylaxe

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