Radioresponsiveness, sublethal damage repair and stem cell rate in spheroids from three human tumor lines: comparison with xenograft data.

Dose-control curves after fractionated irradiation were generated for small oxic spheroids from the two human glioma cell lines, U87 and A7, as well as the squamous cell carcinoma line FaDu. These data were fitted by the linear quadratic model assuming Poisson statistics. The alpha/beta values of A7, U87, and FaDu spheroids, respectively were 10.3 (8.1-12.9) Gy, 17.8 (15.1-21.1) Gy, and 37.9 (29.1-51.5) Gy. These data were compared with those previously published by Suit et al. (31) and Zietman et al. (40) for 6 mm xenografts of U87 and FaDu after fractionated irradiation and for A7 after single dose irradiation under clamped conditions. A good agreement in the alpha/beta values was observed for U87 and Fadu xenografts and spheroids assuming an oxygen enhancement ratio (OER) of 2.7. In addition, the ranking according to the single doses needed to control 50% of the tumors agreed for xenografts and spheroids from the three cell lines. U87 was the most resistant line in both model systems, followed by A7 and FaDu. However, the absolute values of alpha and beta, obtained from the direct fit to the dose-control data were only about half as high for U87 and FaDu xenografts than for the spheroids. Monte Carlo simulations showed that this discrepancy can be explained by a greater tumor heterogeneity of the xenografts. While the number of critical stem cells or spheroid rescuing units equaled the number of cells per spheroid for the three cell lines, the percentage of tumor rescuing units for Fadu and U87 xenografts was estimated to be below 1%. In a next step, survival curves were generated for exponentially growing cells of the three lines. A7 cells were significantly more radioresistant when plated on tissue plastic than in soft agar. Using the most resistance-promoting colony assay conditions for each cell line, a good agreement was observed for the alpha and SF2Gy values calculated from the colony and spheroid control data. This study shows that the spheroid model can quantitatively predict the repair capacity of sublethal damage as well as the rank order of radiation sensitivity of in vivo tumors.     

Antidiuretic-hormone-induced morphological changes in the ampullary epithelium of the frog semicircular canal

Summary Morphological changes induced by in vitro treatment with arginine-vasotocin, the frog antidiuretic hormone, were studied in the ampullary epithelium of the frog semicircular canal. Morphological changes appeared only in the apical side of the dark cells, while the basal part of these cells and the other cells lining the semicircular canal did not show any change. Changes consisted of the appearance of numerous small vesicles in the apical cytoplasm and the development of microvilli on the apical plasma membrane of the dark cells. These results suggest that arginine-vasotocin could play a role in the regulation of endolymph section.     

An Absent Ophthalmic Artery or Carotid Siphon Signal on Transcranial Doppler Confirms the Presence of Severe Ipsilateral Internal Carotid Artery Disease

Transcranial Doppler ultrasound provides a useful adjunct to extracranial ultrasound in the diagnosis of carotid bifurcation disease. Previous studies have shown that collateral flow patterns and diminished flow velocities in the ipsilateral middle cerebral artery correlate with hemodynamically significant carotid disease. In a series of 7,054 carotid duplex and transcranial Doppler examinations, 12.5% (95% confidence interval [CI]: 8.7, 16.4) of 287 ophthalmic arteries ipsilateral to an apparent carotid occlusion had no detectable flow signal, compared with 0.5% (95% Cl: 0.3, 0.7) of 6,767 ophthalmic arteries ipsilateral to a nonoccluded carotid artery (p < 0.001 ). Carotid siphon signals were not detectable in 24.4% (95% Cl: 19.4, 29.4) of arteries ipsilateral to the carotid occlusion, versus 1.0% (95% Cl: 0.8, 1.3) ipsilateral to nonoccluded carotid arteries (p < 0.001 ). A significant number of absent ophthalmic artery and carotid siphon signals (5.7 and 8.7%, respectively) were also found in patients with 80 to 99% extracranial carotid stenosis. A subset of 216 studies with angiographic correlation confirmed the high association of these transcranial Doppler findings with severe stenosis or occlusion of the internal carotid artery. Primary ophthalmological disease or siphon occlusion did not explain these findings. An absent ophthalmic artery or carotid siphon signal on transcranial Doppler examination is believed to represent a failure to detect slow flow distal to severe carotid bifurcation lesions. As a sign of ipsilateral carotid occlusion, the sensitivities of absent ophthalmic artery and carotid siphon signals are quite low (12.5 and 24.4%, respectively). The high specificities of 99.5 and 99.0%, however, make these findings useful in confirming the diagnosis of presumptive carotid occlusion by carotid duplex ultrasound.     

A system for focal intracavitary irradiation of bladder cancer with remote iridium-192 afterloading.

An afterloading system for remote-control focal intracavitary irradiation of bladder cancer is presented. With 192Ir as radiation source, we demonstrated the practicability of the method in 23 chinchilla rabbits. A system for focal intracavitary irradiation of bladder cancer in humans was developed. A guiding tube with an inflatable balloon led to a reproducible vesical diameter. The intravesical part of the tube was shielded with lead and had a slit for focal radiation exposure. Three variant guiding tubes with different positions of the slit were designed to allow irradiation of any part of the bladder. The application is planned in patients with locally advanced tumors who refuse radical cystectomy or who are medically inoperable.     

Frequent ongoing T-cell receptor rearrangements in childhood B- precursor acute lymphoblastic leukemia: implications for monitoring minimal residual disease

Crosslineage T-cell receptor delta (TCR delta) rearrangements are widely used as tumor markers for the follow up of minimal residual disease in childhood B-precursor acute lymphoblastic leukemia (ALL) by polymerase chain reaction (PCR). The major drawback of this approach is the risk of false-negative results due to clonal evolution. We investigated the stability of V delta 2D delta 3 rearrangements in a group of 56 childhood B-precursor ALL patients by PCR and Southern blot analysis. At the PCR level, V delta 2D delta 3-to-J alpha rearranged subclones (one pathway for secondary TCR delta recombination) were demonstrated in 85.2% of V delta 2D delta 3-positive patients tested, which showed that small subclones are present in the large majority of patients despite apparently monoclonal TCR delta Southern blot patterns. Sequence analysis of V delta 2D delta 3J alpha rearrangements showed a biased J alpha gene usage, with HAPO5 and J alpha F in 26 of 32 and 6 of 32 clones, respectively. Comparison of V delta 2D delta 3 rearrangement status between diagnosis and first relapse showed differences in seven of eight patients studied. In contrast, from first relapse onward, no clonal changes were observed in six patients studied. To investigate the occurrence of crosslineage TCR delta rearrangements in normal B and T cells, fluorescence-activated cell sorter-sorted peripheral blood CD19+/CD3- and CD19-/CD3+ cell populations from three healthy donors were analyzed. V delta 2D delta 3 rearrangements were detected at low frequencies in both B and T cells, which suggests that V delta 2-to-D delta 3 joining also occurs during normal B-cell differentiation. A model for crosslineage TCR delta rearrangements in B-precursor ALL is deduced that explains the observed clonal changes between diagnosis and relapse and is compatible with multistep leukemogenesis of B-precursor ALL.     

Bacterio-expert: an integrated system for assisting in the validation of antibiotic sensitivity tests. Retrospective application in 4053 Staphylococcus

Bacterio-expert is a simple expert system for assisting in the validation of antibiotic sensitivity testing. This system is incorporated in a data acquisition and editing program for bacteriologic test (Bacterio program written in Turbo-Pascal for personal computer users by the same authors). The principles of this system are explained and results with 4,053 antibiotic sensitivity tests on Staphylococcus aureus isolates are reported. Approximately 10% of tests required corrections.