Inhibition of lymphoma cell proliferation by supernatant from fibrosarcoma cultures: Preliminary evidence that the inhibitory material is prostaglandin E

Supernatants obtained from mouse fibrosarcoma cultures 48 hr after the addition of fresh medium contained dialyzable material which inhibited the proliferation of syngeneic lymphoma cells , as measured by ³H-thymidine incorporation. Three lines of evidence indicate that the supernatant inhibitory material is probably prostaglandin (PG) E. First, the supernatant and dialysate of the supernatant contained a substance with the same characteristics as PGE₁ or PGE₂ as detected by thin layer chromatography. Second, PGE₂-treatment of lymphoma cells mimicked the inhibition of proliferation observed with supernatant inhibitory substance. Third, indomethacin treatment of fibrosarcoma cultures reduced the amount of supernatant inhibitory substance present.     

The spatial frequency sensitivity of bipolar cells

Retinal bipolar cells constitute the output stage of the outer layer of the retina. There are several constraints on the ability of the bipolar cell array to respond to the different spatial frequency components of the visual image, including (i) electrical coupling in the dendritic tree receiving receptor input; (iii) the "lateral inhibition" mediated by horizontal cells. Using simple mathematical models, we derive analytical expressions for the spatial frequency response of the bipolar cell array for the case in which horizontal cells are presynaptic to bipolar cells (feedforward model) and also for the case in which horizontal cells are presynaptic to receptors (feedback model). The results illustrate the importance of the three factors mentioned in determining the bipolar cells' properties. The optimal spatial frequency for stimulating the bipolar cell array, and the range of spatial frequencies transmitted onward to the inner plexiform layer, are thus related to the anatomical and electrical properties of the cells in the outer plexiform layer.     

Hyperparathyroidism in pregnancy: case report and review of the literature.

The apparent incidence of hyperparathyroidism (HPT) is low in pregnancy but will likely increase now that more asymptomatic HPT is being diagnosed. However, since the serum calcium levels are decreased in pregnant women, mild primary HPT may go unrecognized. In untreated cases of HPT, complications during pregnancy or during the neonatal period have included spontaneous abortion, stillbirth, neonatal death, neonatal tetany and hypercalcemia. A review of the literature indicates a substantial improvement in fetal outcome when parathyroidectomy is done during pregnancy, as in the case reported here. Therefore, parathyroidectomy is the treatment of choice when the diagnosis is made during pregnancy, although oral phosphate therapy may be an alternative if surgery is contraindicated.     

Design optimization of continuous sterilizers

The development of a design of a continuous sterilization is considered with regard to practical data for temperature/time thermal deactivation of infecting organisms. An example of the optimization of the engineering design for capital and operating costs is given. Systems for continuous sterilization by membrane filtration are also considered.     

A cytological basis for the separation of Geropogon from Tragopogon (Compositae: Lactuceae)

The single species ofGeropogon, G. hybridus (L.) Schultz-Bip., is sometimes submerged in the morphologically similarTragopogon. A comparative study of the karyotypes ofGeropogon andTragopogon sensu stricto clarified their relationship. The karyotype ofG. hydridus (2n=14) was compared with that ofT. dubius Scop. (2n=12). The karyotypes are distinct, offering a compelling reason to recognizeGeropogon as a separate genus.     

The gene for aromatase (P450arom) in the chicken is located on the long arm of chromosome 1

An 125I-labeled partial cDNA for the chicken aromatase P450 was used for in situ hybridization to chromosomes from primary chicken embryo fibroblast cultures. The results indicate that the gene that encodes aromatase is located on the long arm of chromosome 1 at approximately position 0.16.     

Inhibitors of sterol synthesis. Characterization of trimethylsilyl dienol ethers of 3 beta-hydroxy-5 alpha-cholest-8(14)-en-15-one. Applications in the analysis of mitochondrial metabolites of the 15-ketosterol by gas chromatography-mass spectrometry.

Derivatization of delta 8(14)-15-ketosterols as bis-TMS dienol ethers facilitates their analysis by gas chromatography-mass spectrometry (GC-MS). Conditions are presented for the preparation of each of the three possible bis-TMS dienol ethers of 3 beta-hydroxy-5 alpha-cholest-8(14)-en-15-one (1), a potent regulator of cholesterol metabolism. Treatment of 1 with N,O-bis(tri-methylsilyl)-trifluoroacetamide (BSTFA) and pyridine for 20 h at 100 degrees C produced primarily 3 beta,15-bis(trimethylsilyloxy)-5 alpha-cholesta-7,14-diene. Treatment of 1 with BSTFA-pyridine in the presence of 0.1% perchloric acid for 20 h at 22 degrees C gave mainly the delta 8(14)15, dienol ether. Heating this reaction mixture at 100 degrees C for 4 days gave mainly the delta 8,14 ether. The structures of the three dienol ethers were established by GC-MS and 1H and 13C nuclear magnetic resonance spectroscopy. The three TMS dienol ethers of 1 were resolved by capillary GC and gave very simple mass spectra upon electron impact with fragmentation limited almost exclusively to the elimination of trimethylsilanol, methyl, and the side chain. The TMS dienol ethers showed reduced artefact formation, improved chromatographic resolution, and increased sensitivity relative to the delta 8(14)-15-ketosterols, properties that improve the detection and identification of minor components in analyses of complex biological mixtures. The utility of this derivatization is illustrated for the delta 7,14 TMS dienol ethers of the 3-deoxy, 3-keto, 3 alpha-hydroxy, and 3 beta-methoxy analogs of 1 and for delta 8(14)-15-ketosterols in mixtures obtained from incubations of 1 with rat liver mitochondria in the presence of NADPH.