Manganese absorption by excised barley roots

Short-term absorption studies with 5-day-old excised barley roots revealed that the basic aspects of Mn absorption were similar to those of other metabolically absorbed cations. Following an initial non-metabolic equilibration with the root, Mn was absorbed for several hours at a slower steady-state rate comparable to that of other inorganic cations. Complete or nearly complete inhibition of the steady-state phase by low temperature, dinitrophenol, and azide provides strong evidence that Mn transport into this tissue was metabolically mediated. Within limits, the rate of transport was strongly dependent upon the concentrations of Mn and the hydrogen ions in the ambient solution. Absorption increased rapidly with increasing concentrations of Mn up to 1 meq per liter. Above this concentration, the rate leveled off, apparently due to a saturation of the transport mechanism. Within the physiological pH range in which Mn is soluble (below pH 7), absorption increased greatly with decreasing hydrogen-ion concentration.     

Teratogenicity of combinations of sodium dichromate, sodium arsenate and copper sulphate in the rat

1. The teratogenicity of sodium dichromate (2 mg Cr/kg), sodium arsenate (5 mg As/kg) and copper sulphate (2 mg Cu/kg) in female Wistar rats was studied following the administration of the test compounds separately and in their various combinations on gestation day 8. 2. The test compounds administered separately and the combination of dichromate plus Cu2+ were non-fetotoxic and either non- or weakly teratogenic, whereas arsenate/Cu2+ was both weakly fetotoxic and teratogenic. 3. Dichromate/arsenate and dichromate/arsenate/Cu2+ caused a marked decrease in mean fetal weight and an increased incidence of fetal resorption and abnormality formation.     

Immunocytochemical analysis of cytocentrifuged fine needle aspirates. A study based on lung tumors aspirated in vitro

The value of Cytospin preparations of fine needle aspiration (FNA) biopsy material for immunocytochemical analysis was investigated using aspirates obtained from 23 resected human lung tumors. The results were compared with those on cryostat sections from the same tumors. The Cytospin preparations of the FNA biopsies gave the best immunostaining reactions and enabled a comprehensive range of monoclonal antibodies (MAbs) to be utilized. The quality of the Cytospin immunostaining compared favorably with that on cryostat sections of the same tumors and generally yielded a similar immunophenotype. However, the Cytospin preparations were not suitable for staining with MAb Ki67, which detects an antigen associated with cellular proliferation. With Ki67, conventionally prepared smears were much superior and enabled an assessment of tumor growth fraction that concurred with the growth fraction calculated from cryostat sections in most cases.     

Activin B: precursor sequences, genomic structure and in vitro activities

We report here the complete amino acid sequence of the human inhibin beta B-subunit as deduced from the sequence of cDNA and genomic clones. The primary translation product of the beta B mRNA predicts a protein of 407 amino acids, containing a prepro region of 292 amino acids separated by basic amino acids from the mature C-terminal 115 amino acids. Mammalian tissue culture cells transfected with a beta B-subunit expression plasmid secreted an activin B homodimer of approximately 22K mol wt. Coexpression of the beta A- and beta B-subunit mRNAs resulted in the secretion of the three forms of activin, A, AB, and B. Purified activin B was shown to elicit FSH release in an in vitro pituitary assay and trigger the accumulation of hemoglobin in K562 cells. The potency of activin B in both of these assays (ED50 approximately 2 ng/ml) was indistinguishable from that observed for activin A.     

Tumor necrosis factor-alpha induces vitamin D-1-hydroxylase activity in normal human alveolar macrophages.

The induction of 1-hydroxylase in alveolar macrophages by tumor necrosis factor-alpha (TNF) was examined in view of recent evidence suggesting that local production of 1,25-(OH)2D3 may play a role in the regulation of immune functions. Incubation of pulmonary alveolar macrophages from normal human subjects with recombinant TNF caused a 2- to 10-fold increase in 25-hydroxyvitamin D3-1-hydroxylase activity. The dose-response curve was linear over the range 0.05-5.0 IU/ml, and no further increase was seen at higher concentrations. The increase in 1-hydroxylase activity was present after 12 h and reached a maximum after 3 days. The effect of TNF was inhibited in a dose-dependent manner by the presence of 1,25(OH)2D3 (10(-10)-10(-8) M) in the incubation media for 5 days but was unaffected by 10(-9) M 1,25(OH)2D3 after 12 h. The enhancement of macrophage 1-hydroxylase activity by TNF was comparable to that induced by gamma interferon (IFN) but the effects of maximal doses of both agents were not additive. The presence of antibody to TNF resulted in a 76% inhibition of TNF-induced 1-hydroxylase but had no significant effect on IFN-induced 1-hydroxylase activity.