Decrease In Rate Of Incorporation Research Articles

The effect of maintenance in vitro on glucose uptake and the incorporation of glucose into glycogen by adult Schistosoma mansoni

The effect of maintenance in vitro on glucose uptake and the incorporation of glucose into glycogen by adult Schistosoma mansoni. International Journal for Parasitology 16: 253–261. Adult male Schistosoma mansoni rapidly depleted their glycogen reserves in vitro. Both sexes also exhibited a gradual reduction in glycogen content during prolonged maintenance. Paired and separated worms were incubated in [ 3H] glucose and rates of glucose uptake and incorporation into glycogen were determined following periods of maintenance in vitro. The glucose uptake rate declined during long-term maintenance and was higher for separated males and females than for equivalent paired worms. Increasing the medium glucose concentration also increased the rate of uptake. Glucose continued to be incorporated into glycogen throughout 10 days in vitro, with evidence from paired schistosomes suggesting that the rapid depletion of male glycogen could be due to a decrease in incorporation rate in vitro. The incubation of separated worms and the use of higher glucose concentrations in media both effected an increase in incorporation rate. These results are discussed in the light of observations of the depletion of schistosome glycogen in vitro.

Primary cultures from defined brain areas; effects of seeding time on cell growth, astroglial content and protein synthesis

The influence of seeding time on cell growth, astroglial content and on protein synthesis during cultivation was determined in primary cultures from 3 phylogenetically different brain areas from rat cerebral cortex, striatum and brainstem. Brainstem cultivated from 17-day-old embryos and all the cultures studied from the 3 brain areas of newborn and 7-day-old rat showed a similar increase in total and water-soluble protein during cultivation. Glial fibrillary acidic protein (GFAp, α-albumin) levels increased with age in all cultures studied. There was a rapid increase in GFAp (α-albumin) between 1 and 2 weeks in cultures from newborn and between 2 and 3 weeks in brainstem cultures from 17-day-old embryos, these increases being slower thereafter. Incorporation of [ 3H]valine into soluble protein was lower in 3-week-old cultures than in 1- and 2-week-old cultures derived from newborn and 7-day-old rat brain. The incorporation rates were similar in comparisons of the various cultures. Similar results were obtained from embryonic cultures, although the decrease in incorporation rate was between 3 and 4 weeks. The efficiency of incorporation (% TCA-precipitated material/total [ 3H]activity) was higher in 2- and 3-week-old than in 1-week-old cultures from newborn and 7-day-old rats and in 3- and 4-week-old cultures of brainstem from 17-day-old rat embryos. These findings suggest a cell differentiation during cultivation. The results show that seeding time has a variable influence on cultures from the different brain areas studied concerning cell growth, astroglial content and probably differentiation during cultivation. Embryonic cell cultures seem, in general, to develop one week later than neonatal and postnatal ones. Cultures of newborn rat cells from cerebral cortex, striatum and brainstem show many similarities in the above parameters during cultivation. This is also the case for brainstem cultures from embryonic rat.

Induction of differentiation of human and murine myeloid leukemia cells in culture by tunicamycin.

Tunicamycin, an antibiotic that specifically blocks the synthesis of N-acetylglucosamine-lipid intermediates and thereby prevents glycosylation of glycoproteins, induced differentiation of both human (HL-60) and murine (M1) myeloid leukemia cell lines in culture. At 0.1-1.0 microgram/ml, it induced differentiation of both HL-60 and M1 cells, characterized by increase in phagocytic cells and changes to resemble mature myeloid cells. Fc receptors were also induced in M1 but not in HL-60 cells; induction of intracellular lysozyme activity was not detected in either HL-60 or M1 cells. With this concentration of tunicamycin, there was marked decrease in rate of incorporation of radioactive glucosamine into macromolecules and a decrease in the rate of DNA synthesis. These data show that glycosylation of cellular proteins has an important role in maintaining these myeloid leukemia cells in an undifferentiated state in culture. The results also indicate that induction of phagocytosis in both HL-60 and M1 myeloid leukemia cells and of Fc receptors in M1 cells does not require continued synthesis of the oligosaccharide portions of cellular proteins by the lipid-linked pathway.

The in vitro effect of oestradiol on collagen metabolism in metaphyseal rat bone.

Surviving bone pieces from the femoral and tibial metaphyses of young castrated female rats have been incubated for 6 hours with concentrations of oestradiol-17-beta ranging from 10(-9) M to 3 x 10(-5) M, and the in vitro collagen metabolism studied. The addition of oestradiol did not produce any change in the resorption patterns of bone collagen, expressed as release of hydroxyproline to the medium. Parathyroid hormone in the incubation medium increased the resorption and decreased the incorporation rate insignificantly. Addition of both parathyroid hormone and oestradiol to the incubation medium produced a significant increase in resorption and a decrease in incorporation rate as compared with the control incubations. The bone pieces incubated with oestradiol-17-beta 3 x 10(-5) synthesized and incorporated significantly less hydroxyproline than the control bone pieces. This is, however, a very high concentration of the hormone and the physiological significance of the observation is doubtful.

Rate of protein synthesis in rat salivary gland cells after pilocarpine or feeding. II. Protein synthesis in vivo in cells of the submandibular and parotid gland after secretion.

The effect of pilocarpine and food uptake on the rate of incorporation of [3H]-leucine in vivo was measured by means of quantitative radioautography in three exocrine cells of the rat: the acinar and the granular duct cells of the submandibular and the acinar cells of the parotid gland. The three cell types react differently. The submandibular acinar cells showed a decrease in incorporation rate after pilocarpine administration but not after feeding. The incorporation rate of the granular duct cells of the submandibular gland remains constant after both stimulations. The acinar cells of the parotid gland show an increase in incorporation rate of [3H]-leucine in response to both. The contrast between the submandibular and the parotid gland could also be demonstrated radiobiochemically, the results reflecting the incorporation rates of the acinar cells of both glands, giving no information on the contribution of other cell types. The decrease in incorporation rate of the submandibular gland acinar cells is accompained by a shift of polyribosomes towards monomers.

Ultraviolet-stimulated thymidine incorporation in xeroderma pigmentosum lymphocytes.

Abstract Autoradiographic and liquid scintillation counting techniques were utilized to measure the ultraviolet (UV)-stimulated incorporation of radioactive thymidine during repair replication of the UV-damaged deoxyribonucleic acid (DNA) of irradiated peripheral blood lymphocytes from 4 patients with xeroderma pigmentosum (XDP) and from normal donors. Lymphocytes from 3 of the 4 patients had a markedly decreased rate of incorporation soon after irradiation in comparison with the rate obtained with normal donors' lymphocytes. However, the duration of incorporation into these 3 patients' lymphocytes was prolonged, so that XDP lymphocytes appear eventually to incorporate as much total thymidine as normal lymphocytes. Lymphocytes from the fourth patient had a rate and duration of thymidine incorporation after irradiation similar to normal lymphocytes. This patient, therefore, may have a different genetic and biochemical defect from the other XDP patients.

The Effect of 6-Mercaptopurine on the Incorporation of Labeled Amino Acids into Cellular Protein of Chronic Granulocytic Leukemia Leukocytes

Abstract The leukocytes of chronic granulocytic leukemia incorporate labeled valine and leucine at a higher rate than normal leukocytes. 6-mercaptopurine causes significant decrease in the rate of amino acid incorporation into cellular protein of leukemic cells. The onset of a sharp decrease in the amino acid incorporation rate by granulocytic leukemic cells occurs only after several days of therapeutic oral doses of 6-mercaptopurine. The decrease in incorporation rate precedes the decrease in circulating leukocytes by several days, indicating that damage to a vital function of these cells occurs before their disappearance from the blood stream. The decrease in the amino acid incorporation rate persists as long as the leukemia is in remission and even after therapy has been stopped; it exists until exacerbation occurs. Increase in incorporation accompanies exacerbation of the leukemic cell count. A possible action of 6-mercaptopurine is its role in interference with amino acid incorporation into cellular protein of chronic granulocytic leukemia cells.

Uptake of glycine-1-C14 by connective tissue. III. Effects of adrenal hormones and aging.

When glycine-1-C14 is injected into rats bearing Ivalon sponges implanted 2 weeks previously, significant radioactivity is found in the various protein fractions (including collagen) of the sponge connective tissue after 6 hours. Adrenalectomy at the time of implantation exerted some influence upon the extent of incorporation into some of the fractions, but administration of hydrocortisone for 2 days to either intact or adrenalectomized animals had no effect. When studies of glycine uptake by sponge-biopsy connective tissue proteins were made in rats of various ages, a steady decrease in rate of incorporation into all fractions was observed as age of the host increased from one month to one year.