Mean, geometric mean, or median grain count in cell cycle studies

Steroid regulation of calcitonin gene-related peptide mRNA expression in motoneurons of the spinal nucleus of the bulbocavernosus

Motoneurons express calcitonin gene-related peptide (CGRP). Previous studies have shown that CGRP immunoreactivity is regulated by testosterone in the androgen-sensitive motoneurons of the spinal nucleus of the bulbocavernosus (SNB). In this research the effect of plasma levels of testosterone on the expression of alpha CGRP mRNA in the SNB motoneurons of adult male rats was studied with in situ hybridization. The number of motoneurons expressing alpha CGRP mRNA and the level of alpha CGRP mRNA expression was significantly higher in the SNB of castrated male rats than in the SNB of gonadally intact rats. Using a 5x background labeling criterion in castrated rats 88.1 +/- 4.5% while in intact rats 75.3 +/- 6.4% of SNB motoneurons expressed alpha CGRP mRNA. Testosterone replacement at the time of castration prevented the effect of castration on the expression of alpha CGRP mRNA in SNB motoneurons. In castrated rats, the increase in the number of SNB cells expressing CGRP was the result of increased steady state levels of alpha CGRP mRNA in all SNB neurons.

A modification of the grain count halving method for detailed analysis of cell kinetic parameters

A modification of the conventional grain count halving (GCH) method is presented. By determining the decrease of the mean grain number of all interphase cells in addition to that of all labelled interphase cells on the same autoradiographs, the potential doubling time Tpot (or the cell production rate kp) can be obtained in one and the same experiment. Thus the modified GCH method provides not only the cycle time of the cell population studied but also the growth fraction and, with additional cytofluorometric measurements, the duration of all cycle phases. By evaluating the cell production rate and the growth fraction this method leads to more reliable cell kinetic data of experimental tumours and human tumours growing in nude mice. In contrast to other cell kinetic methods, the modified GCH method can also be applied in special cases to human tumours in vivo, since only few points of measurement are needed. A comparison of the cell kinetic results obtained by the modified GCH method with those derived from the fraction of labelled mitoses method, both applied to allotransplants of the adenocarcinoma EO 771 in nude mice, shows good agreement.

Rate and time of DNA synthesis of human leukaemic blasts in bone marrow and peripheral blood

We have evaluated DNA synthesis rate (S rate) and time (Ts) and tritiated thymidine labelling index (LI) of peripheral blood (PB) and/or bone marrow (BM) leukaemic blasts (Bl) in nineteen cases of acute leukaemia (twelve non-lymphoblastic, AnLL, and seven lymphoblastic, ALL), in one case of non-Hodgkin's leukaemic lymphoma and in a case of plasma cell leukaemia. The LI of PB-Bl was significantly lower than that of BM-Bl (range 0.1-6.2% and 1.9-19.5%, respectively; P less than 0.01). The S rate was higher for PB-Bl than for BM-Bl (range 3.5-11.3 and 2.5-9.5 mol X 10(-18)/min; P less than 0.02) and the Ts of PB-Bl was shorter than that of BM-Bl (range 7.6-22.1 and 10.8-34.7 hr, respectively; P less than 0.02). In eight cases where S rates of both BM-Bl and PB-Bl were available, a linear correlation (r = 0.82; P less than 0.01) was found between the two parameters. This suggests that the DNA synthetic rate is a property of the leukaemic cell line in individual patients and differs from case to case. It further indicates that the environmental influences on the DNA synthesis rate in BM or PB are always of the same order of magnitude. From the results of this study we speculate that the DNA synthesis rate of leukaemic blasts is slowed down in the BM by environmental factors such as cell density.

Proliferative kinetics of central nervous system (CNS) leukemia

The proliferative kinetics of the leukemic cells in the cerebrospinal fluid (CSF) were studied in three adults with CNS leukemia after 18 and 8 months while receiving an intensive treatment regimen. One (J.L.) had acute myeloblastic leukemia and developed CNS disease after 5 years' treatment with arabinosylcytosine and 6-thioguanine. All were in marrow remission at the time of study. G.H. had had no therapy for CNS disease, A.K. had had intrathecal methotrexate 2 months previously, and J.L. had recently completed radiotherapy (1900 R) to the head. An Ommaya reservoir was placed in a lateral ventricle and 3H-thymidine was injected into the resrvoir every 12 hours for 10 days; samples of cells were obtained by lumbar puncture periodically for autoradiography. In all patients the flash 3H-thymidine labeling index (LI) of the leukemic cells was less than 2% (determined in vitro) and the mitotic index less than 0.1%. After 10 days of 3H-thymidine injections in vivo, the LIs of the leukemic cells were 55%, 36%, and 21% in G.H., A.K., and J.L., respectively. These findings indicate that leukemic cells may proliferate very slowly in the CNS, and stress the difficulty of eradicating CNS leukemia with chemotherapeutic agents which are only active against proliferating cells.