Neurological and electroencephalographic changes in newborns treated with prostaglandins E2 and E2

Six newborns with obstructive right heart lesions were examined neurologically and electroencephalographically during treatment with prostaglandin (PG) E₁ or E₂ given to maintain patency of the ductus arteriosus and to increase pulmonary blood flow. PG was administered intravenously or intraarterially in the aortic isthmus proximal to the ductus arteriosus. Besides a rise in arterial oxygen saturation, all patients had some sign of central nervous system involvement. The electroencephalogram showed minor changes suggestive of sedation. In addition, three patients in whom PG given intravenously presented various combinations of neurological abnormalities (“myoclonic jerks”, apnoeic spells, hiccup) of subcortical origin. Side-effects subsided after stopping the treatment anf posed no problem in the management of the patients. These findings confirm the usefulness and safety of the PG therapy and indicate that the intraaortic route of administration is preferable.     

The differential effects of PGE on the immune response in normal and immunosuppressed mice

The effect of 16,16-dimethyl-PGE₂-methyl ester (di-M-PGE₂) on humoral and cellular immunoresponsiveness has been compared in normal mice and in mice immunosuppressed by splenectomy and thymectomy plus antithymocyte serum (ATS). Splenectomy resulted in immunosuppression manifested by augmentation of B-16 melanoma growth; this stimulatory effect was reversed by di-M-PGE₂. In animals immunosuppressed by thymectomy plus ATS, di-M-PGE₂ augmented the humoral and cellular immune responses; this was manifested by slowing of the growth of B-16 melanoma and by stimulating the number of plaque-forming cells, hemagglutinin titers, and delayed-hypersensitivity reactions to sheep erythrocytes. In contrast, in normal (nonthymectomized) mice, di-M-PGE₂ was mildly immunosuppressive. Finally, adriamycin-immunosuppressed normal mice and this suppression were reversed by the addition of di-M-PGE₂ to the treatment regimen.     

AT1 Angiotensin Receptors Mobilize Intracellular Calcium in a Subclone of NG108–15 Neuroblastoma Cells

The effects of angiotensin II (AII) and related peptides on the mobilization of internal Ca2+ were studied in a subclone of NG 108-15 cells. The subclone, C1, was prepared by fluorescence-activated cell cloning using a rapid response kinetics and a large response magnitude following stimulation by AII as the selection criteria. Angiotensin I, AII, and angiotensin III (AIII) stimulated Ca2+ mobilization in the C1 cells in a concentration-dependent manner (1 nM-100 microM), yielding EC50 values of 437 +/- 80 nM (n = 4; slope = 1.6 +/- 0.3), 57 +/- 8 nM (n = 12; slope = 1.5 +/- 0.3), and 36 +/- 5 nM (n = 7; slope = 1.4 +/- 0.3), respectively. AIII was significantly more potent than AII (p less than 0.05). In contrast, Des-Phe8-AII, AII-hexapeptide (AII 3-8), and p-NH2-Phe6-AII (1-10 microM) were inactive as agonists. Although the effects of AII and AIII in C1 and parent NG108-15 cells were totally inhibited by the AT1 receptor-selective nonpeptide antagonist, DUP-753 (0.3-1 microM), the AT2-selective antagonists, EXP-655 and CGP42112A (1-10 microM), failed to block the effects of AII. DUP-753 (0.3-100 nM) produced dextral shifts of the AII-induced concentration-response curves and yielded an estimated affinity constant (pA2) of 8.5 +/- 0.2 (n = 16) using single-point analysis involving different concentrations of DUP-753. These data compared well with those obtained for the inhibition of AII-induced aortic contractions by DUP-753 (pA2 = 8.5) reported previously by others.(ABSTRACT TRUNCATED AT 250 WORDS)     

Chemical quantitation of hemoglobin glycosylation: fluorometric detection of formaldehyde released upon periodate oxidation of glycoglobin

A sensitive fluorometric method for the quantitation of hemoglobin glycosylation, based upon periodate oxidation of the carbohydrate moieties present on both the α- and ?-amino groups of globin is described. The formaldehyde product is measured as the fluorescent 3,5-diacetyl-1,4-dihydrolutidine formed from the condensation of formaldehyde with acetylacetone and ammonia.This method is rigorously designed to assay glycosylated hemoglobin levels and to give a direct measure of the number of glycogroups per milligram of hemoglobin. It requires only 1 mg of protein and may also be used to determine the extent of the nonenzmatic glycosylation of other proteins.     

A DNA-binding fraction of mouse kidney 3-ketosteroid reductase: Comparison with androgen receptors

Since approximately 1% of 3-ketosteroid reductase (which metabolizes dihydrotestosterone [17β-hydroxy-5α-androstan-3-one] to 5α-androstane-3α,17β-diol or 5α-androstane-3α,17β-diol) from mouse kidney cytosol adheres to DNA under conditions that allow virtually complete androgen receptor binding, these two DNA-binding activities were compared in cytosol extracts of mouse kidney and hypothalamus-preoptic area. This DNA-binding fraction of 3-ketosteroid reductase was distinguished from androgen receptor in several ways: (1) its pattern of elution from DNA-cellulose with steps of increasing NaC1 concentration differed from that for receptors from wild-type kidney; (2) it was influenced differently by the mutation Tfm, both in level and in DNA-cellulose elution pattern; (3) in mouse kidney cytosol it was relatively stable at moderate (25°C) temperatures which rapidly inactivated ligand-free androgen receptors in the same cytosols; (4) the DNA-binding was not proportional to androgen receptor levels between two wild-type tissues, the hypothalamus-preoptic area and kidney. By these criteria, a simple relationship of androgen receptors and a DNA-binding fraction of 3-ketosteroid reductase activity is unlikely.     

Lipid participation in intracellular freezing avoidance mechanisms of lettuce seed

Freeze-fracture electron microscopy was used to study water content related freezing resistance in Grand Rapids lettuce seeds. Consistent and recognizable conformational changes occurred in lipid-water phases of lettuce seeds at different moisture contents. In air-dry lettuce seed cotyledons, the lipids lying in spherical lipid bodies near the cell wall appeared amorphous, while the structure was crystalline above 20% water content. The lipid bodies interassociated into membrane bilayers in seeds containing 20 to 25% water. Such lyotropic phase transitions in membrane lipids during lettuce seed hydration are believed to contribute to the biphasic freezing behavior observed in lettuce seeds at different moisture contents and to provide a natural freezing tolerance mechanism for highly desiccated plant tissues such as seeds.     

Characterization of cross-reacting antigens on the Epstein-Barr virus envelope and plasma membranes of producer cells.

A rabbit antiserum has been prepared against the B95-8 transforming strain of EBV. The antiserum has a high virus neutralizing titer (approximately 1:1000) against both the marmoset B95-8 EBV and the human P3HR-1 EBV. The neutralizing antibodies may be absorbed completely with EBV producer cell lines, but not with nonproducer cell lines or producer cell lines treated with phosphonoacetic acid (PAA) so as to be nonproducer. After repeated absorption with PAA-treated B95-8, the serum remains reactive with the membranes of producer cell lines as judged by immunofluorescence or the 125I--Staphylococcal protein A radioimmunoassay. Thus the neutralizing antigens are expressed on the membranes of producer cell lines and may be purified from this source using the serum and 125I--Staph A binding as an assay. The ability of the serum to differentiate between producer and nonproducer cells by means of cell surface determinants has been exploited to achieve a separation of these two populations from the same culture. Immunoprecipitation by the protein A technique shows that the serum recognizes two polypeptides from producer cells of approximate molecular weights 150,000 and 75,000.