A comparison of membrane components of normal and transformed BALB/c cells.

Membrane glycolipids, glycoproteins, and surface proteins of normal and transformed BALB/c cell lines have been compared. Several virally and spontaneously transformed cell lines showed differences in membrane components compared to normal A31 cells. These differences consisted of increased amounts of simpler gangliosides, absence of the large external transformation sensitive (LETS) protein, and the appearance of a major new glycoprotein band of about 105 000 molecular weight. In contrast, the spontaneously transformed cell line that caused the fastest growing tumors in vivo and the most rapid animal death (3T12T) did not have these changes. A31 and 3T12T glycolipid profiles appear similar as did glycoproteins and cell surface proteins detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. When Pronase-generated glycopeptides were analyzed by Sephadex G-50 chromatography, and enrichment in faster-eluting species was seen in two killing tumor lines (c5T and 3T12T) compared to A31. Regressing tumor lines (MSC, c5) did not show this change. Isolated membrane glycoproteins yield glycopeptides of different sized after Pronase digestion. In addition, several 3T12T glycoproteins yield glycopeptides that are larger than those from the corresponding glycoproteins of A31 cells. It appears that glycopeptide alterations associated with transformation occur in several membrane glycoproteins.     

Histiocytic sarcoma of the scrotum in a rat

A 225-day-old male fourth generation rat from a developing recombinant inbred line (Lewis x Brown Norway) had a bilaterally symmetrical enlargement of the scrotum. Palpation indicated the presence of a firm lobulated mass extending from the tip of the scrotum to the abdominal wall. Bilateral nodular masses totally occupied the scrotal sacs, surrounded the testicles, and extended along the spermatic cords into the abdominal cavity. Tumor nodules also were present in the intestinal mesentery, omentum, mesenteric lymph nodes, pancreas, and lung. Histologically, the neoplasm presented a spectrum of characteristics varying from that of a granuloma with giant cells to a diffuse proliferation of spindle-shaped mononuclear cells.     

Column chromatography of plant polyphenols on weak anion exchangers.

Mixtures of phenols and cinnamic acid derived plant polyphenols are separated on several WAX cellulose materials and on DEAE Sephadex. Reference mixtures are also split up into the following distinct groups: phenolic carboxylic acids--neutral o-dihydroxy phenolics--neutral non o-dihydroxy phenolics. Quantitative recoveries are obtained, while no isomerizations occur with the pH labile plant phenolics. It is suggested that these materials can be used for preparative scale purification of plant phenolics, or for cleaning up plant extracts prior to HPLC examination.     

Rapid separation and quantitation of 3',5'-cyclic nucleotides and 5'-nucleotides in phosphodiesterase reaction mixtures using high-performance liquid chromatography

A simple, rapid high-performance liquid-chromatography system for the fractionation and direct quantitation of substrates and products in crude phosphodiesterase reaction mixtures is described. Phosphate buffers and a pellicular anion exchange resin are used at ambient temperature. The method is sensitive, measuring picomoles of products with ultraviolet detection and femtomoles with isotopic measurement, and offers several advantages over the more popular batch sorption and manual methods for measuring phosphodiesterase activity. The time required for analysis, less than 8 min for single substrate reaction mixtures, is a fraction of that required with other chromatographic systems, and precision is +/- 5%. Results of studies with an activatable form of phosphodiesterase demonstrate the accuracy, precision and utility of the procedure for biochemical analyses.     

Production of rhodomycins inStreptomyces griseoruber 4620

The strainStreptomyces griseoruber 4620 produces, besides the anthracycline antibiotics beromycins, some other anthracyclines of the rhodomycin type. Twelve isolates exhibiting a higher antibiotic activity (up to 2.5×), as compared to the parent strain, were obtained after a spontaneous selection. The following species were isolated from the hydrolysate of mycelial extract: β-rhodomycinone, β-isorhodomycinone, α₂-rhodomycinone and 10-deoxy-β-rhodomycinone, which has not yet been described.     

Effects of cycloheximide on the uterine refractory state induced by 'nidatory' oestrogen in rats.

After priming with oestradiol, ovariectomized rats were given 6 days of progesterone treatment in which two doses of 50 ng oestradiol were given on Days 3 and 6. This basic treatment allows the oestradiol-induced (1st injection) disappearance of uterine sensitivity to decidual stimuli to occur. Cycloheximide could not mimic oestrogen action in the production of the uterine refractory state. However, a high dose (500 micrograms per animal) of this inhibitor given with the first injection of oestradiol allowed the uterus to remain in a neutral state and to respond to decidual induction after the second dose of oestradiol. By delaying the injection of cycloheximide after the first oestrogen treatment, protein synthesis requisite to the occurrence of uterine refractoriness would not take place within 12 h after the 'nidatory' oestrogen injection.     

Adenosine dimethylation of 16S ribosomal RNA: effect of the methylgroups on local conformational stability as deduced from electrophoretic mobility of RNA fragments in denaturing polyacrylamide gels.

The electrophoretic mobility of RNA fragments derived from the 3'-end of 16S rRNA on slabs of polyacrylamide gel in the presence of urea is strongly influenced by dimethylation of the N6-aminogroup of two adjacent adenosines. This is not due to the presence of the methylgroups per se, but must be ascribed to an effect of methylation on long range intramolecular interactions at these denaturing conditions. When it is assumed that the electrophoretic mobilities of the RNA fragments in the polyacrylamide matrix are determined by the conformational state(s) of the fragments, dimethylation of the adenosines leads in the smaller fragments to a less compact average conformation and in the larger fragments to a more compact average conformation. An effort is made to comprehend the effects of adenosine dimethylation in terms of secondary structure based on nucleotide sequence.     

Prolactin levels and the LH-response to synthetic LH-RH in the lactating sow

To determine the role of prolactin in the suppression of ovarian activity during lactation in the sow experiments were performed to investigate a possible inhibitory action of prolactin at the pituitary level. Therefore the LH-response to an intravenous injection of 25 μg synthetic LH-RH was measured in the 1st, 2nd and 3rd week of lactation. The compound was injected under high and low concentrations of prolactin in the peripheral blood, the latter achieved by removal of the piglets 6 h before administration of LH-RH. The results showed no difference in the effect of LH-RH injected at high or low prolactin levels. However, although the mean prolactin concentrations in the 1st, 2nd and 3rd week of lactation were similar, the results clearly demonstrated an increase in LH-response as lactation proceeds.The low responsiveness of the pituitary shortly post partum was also observed when the preparturient rise of prolactin was suppressed by treatment with bromoergocryptine. Injections of LH-RH in the last week of gestation given before and after the physiological increase of PRL, which occurred about 48 h before delivery, all showed low LH-response.It is obvious from the presented data that the LH-response to an intravenous injection of 25 μg LH-RH is in no way correlated with the prolactin levels at the time of treatment.