Mesenteric oxyhemoglobin desaturation improves with patent ductus arteriosus ligation.

Near-infrared spectroscopy was used to monitor cerebral and mesenteric regional oximetry in a preterm neonate undergoing surgical ligation of a patent ductus arteriosus. This patient initially demonstrated severe mesenteric oxyhemoglobin desaturation, which improved immediately following ductal ligation.

The human prostatic carcinoma cell line LNCaP expresses biologically active, specific receptors for 1 alpha,25-dihydroxyvitamin D3.

The LNCaP prostatic carcinoma cell line was examined for the presence of specific receptors for 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25-(OH)2D3]. Whole cell binding studies identified approximately 2500 high-affinity (Kd = 1.4 x 10(-9) binding sites per cell. Competition studies revealed that these receptors are specific for the 1 alpha,25(OH)2 metabolite. Binding studies using the synthetic androgen R1881 indicate that separate androgen and vitamin D3 receptors exist in LNCaP cells. The vitamin D3 receptors sediment at approximately 3.5S on linear sucrose gradients. The sedimentation coefficient could be shifted with a monoclonal anti-vitamin D3 receptor antibody (9A7 gamma) but not with a monoclonal antibody to the androgen receptor (AN1-15). The receptor/ligand complex elutes from native DNA cellulose at 0.2 M KCl. Northern blot analysis identified an mRNA of approximately 4.6 kilobases which hybridized with a specific vitamin D3 receptor complementary DNA probe (hVDR). In the absence of androgens, 1 alpha,25(OH)2D3 stimulated growth and prostate-specific antigen production by LNCaP cells in a dose-dependent fashion. Dose-response curves indicated that at physiological concentrations (10(-9) M) 1 alpha,25(OH)2D3 was mitogenic, whereas at higher concentrations (10(-8) M) it promotes differentiation. These studies suggest that 1 alpha,25(OH)2D3 could play an important role in the natural history of and response to hormone therapy by prostatic cancer.

Vitamin D receptor expression, 24-hydroxylase activity, and inhibition of growth by 1alpha,25-dihydroxyvitamin D3 in seven human prostatic carcinoma cell lines.

Although prostatic cancer is often viewed as an androgen-dependent malignancy, a number of other hormones including 1alpha, 25-dihydroxyvitamin D3 [1alpha,25(OH)2D3] are now recognized to modulate its growth and differentiated phenotype. Seven different continuous human prostatic carcinoma cell lines were examined for the presence of biologically active receptors for 1alpha,25(OH)2D3. All seven lines were found to contain mRNA for the vitamin D receptor using an RNase protection assay. Six of the seven cell lines were found to have high-affinity saturable binding sites for 1alpha,25(OH)2D3. The seventh line was found to contain vitamin D receptors by sucrose gradient analysis. All seven lines were found to express 24-hydroxylase activity by a HPLC assay that measures the conversion of 25-hydroxyvitamin D3 to 24,25-dihydroxyvitamin D3. 24-Hydroxylase activity was up-regulated in all seven cell lines by preincubation with 1alpha,25(OH)2D3. In the presence of fetal bovine serum, the growth of four of the seven cell lines was inhibited. In the majority of cell lines growth inhibition was related not only to the number of receptors per cell, but also in inverse proportion to the 24-hydroxylase activity of each cell line. The ubiquitous presence of vitamin D receptor and 24-hydroxylase activity in human prostatic carcinoma cells suggests new alternatives for the pharmacological treatment of advanced prostatic cancer and implies that chemoprevention strategies could also make use of this endocrine axis.

Repair of radiation-induced damage to the cell division mechanism of Escherichia coli.

Adler, Howard I. (Oak Ridge National Laboratory, Oak Ridge, Tenn.), William D. Fisher, Alice A. Hardigree, and George E. Stapleton. Repair of radiation-induced damage to the cell division mechanism of Escherichia coli. J. Bacteriol. 91:737-742. 1966.-Microscopic observations of irradiated populations of filamentous Escherichia coli cells indicated that filaments can be induced to divide by a substance donated by neighboring cells. We have made this observation the basis for a quantitative technique in which filaments are incubated in the presence of nongrowing donor cells. The presence of "donor" organisms promotes division and subsequent colony formation in filaments. "Donor" bacteria do not affect nonfilamentous cells. An extract of "donor" cells retains the division-promoting activity. The extract has been partially fractionated, and consists of a heat-stable and a heat-labile component. The heat-stable component is inactive in promoting cell division, but enhances the activity of the heat-labile component. The division-promoting system is discussed as a radiation repair mechanism and as a normal component of the cell division system in E. coli.