Increase In Deoxyribonucleic Acid Content Research Articles

A morphological, biochemical, and radioautographic study in rats

Splenectomy has long been an establishmd surgical procedure in various conditions, including trauma. Because total splenectomy has often been correlated with sepsis, every surgeon tries to preserve as much of the injured spleen as possible. Contradictory reports have been published as to whether regeneration of the remaining splenic tissue is possible. In the present study, 28 Sprague-Dawley rats (≈ 100 g) were divided into four groups. They underwent two-thirds partial splenectomy; the remaining splenic tissue was examined after 1 day, 1 week, 1 month and 3 months postoperatively. The following parameters were determined: weight, length, and protein and deoxyribonucleic acid (DNA) content of the remaining spleen. The incorporation of 3H-thymidine into the remaining spleen tissue was also measured. Histology and radioautography were studied in parallel. Results were compared with control animals that were operated upon but with no partial splenectomy. One day, 1 week, and 1 month following partial splenectomy, a slight increase in weight, length, protein, and DNA content as well as incorporation of the radioisotope into cellular DNA was found. By 3 months after the operation, there was no difference in the above parameters between the experimental animals and controls.

Stimulatory effect of beta-alanyl-L-histidinato zinc on cell proliferation is dependent on protein synthesis in osteoblastic MC3T3-E1 cells.

The effect of beta-alanyl-L-histidinato zinc (AHZ) on bone metabolism was investigated in osteoblastic MC3T3-E1 cells. Cells were cultured for 3 days at 37 degrees C in a CO2 incubator in plastic dishes containing alpha-modified minimum essential medium supplemented with 10% fetal bovine serum. After the cultures, the medium was exchanged for that containing 0.1% bovine serum albumin plus various concentrations of AHZ or other reagents, and the cells were cultured further for appropriate periods of time. The presence of AHZ (10(-7)-10(-5) M) stimulated the proliferation of cells. AHZ (10(-6) and 10(-5) M) increased deoxyribonucleic acid (DNA) content in the cells with 48 hr-culture. This increase was completely blocked by the presence of cycloheximide (10(-6) M) or hydroxyurea (10(-3) M). Also, the presence of cycloheximide (10(-6) M) completely inhibited the AHZ (10(-5) M)-induced increase in the proliferation of cells. Meanwhile, parathyroid hormone (10(-7) M), estrogen (10(-9) M) and insulin (10(-8) M) significantly increased cellular DNA content. However, these hormonal effects clearly lowered in comparison with that of AHZ (10(-5) M). Dibutyryl cyclic AMP (10(-4) M) and zinc sulfate (10(-5) M) did not cause a significant increase in cellular DNA content. The present results support the view that AHZ has a direct specific proliferative effect on osteoblastic cells in vitro and that this effect is dependent on protein synthesis.

Effect of Arterial Infusion of Bleomycin on Esophageal Carcinoma — An Evaluation by Nuclear Cytophotometry —

In order to determine the histological changes after a single infusion of bleomycin (BLM) into the aortic esophageal artery (BLM A.I.), resected specimens from 58 patients with esophageal carcinoma (27 cases with BLM A.I., 14 untreated cases, 13 cases with radiation therapy and four cases with combined therapy of radiation and BLM) were examined and evaluated by Feulgen microspectrometry for nuclear deoxyribonucleic acid (DNA) content. The histological changes following the BLM A.I. were characterized by degeneration and necrosis at the front of the invading carcinoma tissue accompanied by inflammatory cell infiltration with foreign body giant cells and fibrosis. In comparison with untreated cases, BLM-treated cases showed an increase in nuclear DNA content and a wide dispersion of the DNA values especially at the perinecrotic area and at the front of advancing carcinoma nests. Therefore, a histological effect of the BLM A.I. was shown by the measurement of the nuclear DNA content of carcinoma cells.

Changes in serum proteins and in major liver constituents following carbon tetrachloride and a high-fat choline-free diet in rats.

Both carbon tetrachloride and a high-fat, low-protein choline-free diet cause hepatomegaly in rats due to an accumulation of both lipids and proteins with a concomitant increase in deoxyribonucleic acid content. CCl4 causes a decline in hepatic glycogen. Serum albumin level is decreased in CCl4-treated rats and increased in those fed the experimental diet.

Flow microfluorometric quantitation of the blastogenic response of lymphocytes.

A method for quantitating the specific stimulation of peripheral lymphocytes has been developed using the techniques of flow microfluorometry. Peripheral bovine lymphocytes were collected and specifically stained for deoxyribonucleic acid (DNA) content using a low-salt propidium iodide procedure. Flow microfluorometry was used to determine, on the basis of DNA content, the percentage of cells in a population that was stimulated. Extremely uniform staining of the lymphocytes (coefficient of variation of less than 2%) provides a high resolution between proliferating and nonproliferating cells. The method provides a rapid, highly repoducible technique for determing the fraction of lymphocytes stimulated in response to tuberculin antigens based on an increase in cellular DNA content. Specific and nonspecific stimulation by a defined antigen can be measured and resolved.

Requirement of deoxyribonucleic acid synthesis for microcycle sporulation in Bacillus megaterium.

Bacillus megaterium cells have been examined during outgrowth for their macromolecular content, ability to undergo microcycle sporulation, the time of their growth division, the time of deoxyribonucleic acid (DNA) replication initiation, and their ability to synthesize DNA after transfer to sporulation medium. The increase in total DNA content of the cells increased discontinuously beginning at 90 min. Thymidine incorporation became insensitive to chloramphenicol between 90 and 105 min of outgrowth. At 90 min the cells acquired the ability to undergo microcycle sporulation and the degree of sporulation depended on the time spent in outgrowth, with maximal sporulation occurring at 180 min. During outgrowth, cells underwent one synchronous growth division beginning at 225 min and ending at 270 min. Outgrowing cells were not able to continue DNA synthesis after transfer to sporulation medium. The data suggest that DNA replication starts before cells are able to undergo microcycle sporulation; however, the initiation of replication may not be the only requirement for microcycle sporulation.

Potentiation of Effect of Prolactin by Adrenocorticotropic and Growth Hormones Upon Weight and Nucleic Acids Contents of Female Rat Mammary Gland

Effects of prolactin, adrenocorticotropic hormone, growth hormone, adrenalectomy, adrenalectomy and corticoids, and adrenalectomy plus prolactin or growth hormone upon the adult female rat mammary gland were investigated.Endogenous hormone effects were studied in rats bearing a transplantable pituitary mammotropic tumor which secretes large quantities of adrenocorticotropic hormone and prolactin. In 40 days the tumor produced a 380% weight increase and 460% increase in deoxyribonucleic acid content of mammary glands in intact rats in contrast to 95% and 297% increase in adrenalectomized rats (10 days after the rats were adrenalectomized). Inhibitory effects of adrenalectomy were prevented by administration of hydrocorticosterone but not by deoxycorticosterone. Administration of growth hormone elicited an increase in gland weight and deoxyribonucleic acid content (70% and 110%) in intact tumor bearing females but not in adrenalectomized animals (—50% and —10%).Prolactin produced mammogenic effects in normal adrenalectomized female rats. Adrenocorticotropic hormone or growth hormone administered separately did not produce any noticeable change in the mammary gland, but effects of prolactin on mammary gland weight and deoxyribonucleic acid content were greatly potentiated by simultaneous injections of adrenocorticotropic hormone and/or growth hormone.

Action of growth hormone and thyroxine on aortas of hypophysectomized dogs.

Young dogs were surgically hypophysectomized and maintained for eleven weeks postoperatively with age-matched normal controls. For three weeks prior to sacrifice, four hypophysectomized dogs were given daily injections of bovine growth hormone (GH, 0.2 mg./kg.) and another four were given daily injections of thyroxine (T4, 5 μg./ kg.). Aortas were removed, cleaned of adventitia and divided into three segments: arch, thoracic and abdominal. Each portion was analyzed for collagen, elastin, deoxyribonucleic acid (DNA), calcium, total mucopolysaccharides (MPS), hyaluronic acid (HA), heparan sulfate (HS), dermatan sulfate (DS) and chondroitin sulfate (GS). The arch and thoracic aortas of normal animals were found to contain more DNA, CS and elastin but less collagen than the abdominal aorta. Removal of the hypophysis resulted in an overall increase in elastin and DNA content and caused a decrease in all sulfated MPS. Administration of either CH or T4 to hypophysectomized dogs had a profound effect on the majority of constituents in all segments of aorta. GH returned the content of elastin, DS and CS toward normal in at least two of the three aortic segments. T4 returned the content of DNA, DS and CS toward normal in all segments. Moreover, T4 treatment caused significant reductions in collagen and HA contents of thoracic and abdominal segments. These results indicate that: (1) the composition of normal aorta varies with the segment studied; (2) the composition of the aorta is markedly affected by hypophysectomy, CH and T4 treatment; and (3) individual aortic segments show differential sensitivity to a given hormone.

Distribution of deoxyribonucleic acid complementary to the ribonucleic acid of avian myeloblastosis virus in tissues of normal and tumor-bearing chickens.

(3)H-labeled 70S ribonucleic acid (RNA) from purified avian myeloblastosis virus (AMV) was used as a probe in deoxyribonucleic acid (DNA)-RNA hybridization experiments to detect the presence of DNA complementary to the AMV genome in various tissues from noninfected normal chickens and from chickens infected with AMV. There was a remarkable constancy in the average cellular concentration of virus-specific DNA found in every tissue from the same uninfected chicken, and even in different chickens from the same strain. In contrast, different tissues from chickens bearing AMV-induced kidney tumors (embryonal nephromas) revealed an unequal distribution in the average virus-specific DNA content per cell. The increase was limited to tumor cells and to tissues that contain target cells for AMV, i.e., red blood cells, kidney cells, and possibly leukocytes. The red blood cells from AMV-infected chickens suffering from acute myeloblastic leukemia, although producing no virus, contained as many viral genome equivalents per cell as did leukemic myeloblasts known to produce large quantities of AMV. An increased viral DNA content was observed in the target cells of chickens that did not show any sign of tumor formation 6 months after infection with AMV. This study demonstrates that vertically transmitted viral DNA is uniformly and stably distributed among all tissues of the offspring, but that horizontal infection after hatching results in an increase in viral DNA content only in some dividing, target tissues that may or may not give rise to neoplasias.

The action of insulin, growth hormone, and epinephrine on cell growth in liver, muscle, and brain of the hypophysectomized rat.

Extract: This study explores changes in deoxyribonucleic acid (DNA), ribonucleic acid (RNA), protein, and water content of muscle, liver, and cerebrum in hypophysectomized rats and the effects of injecting growth hormone, insulin, or growth hormone with epinephrine conjointly over an eleven-day period. Male hypophysectomized rats, 26 to 49 days of age, fed an ad libitum diet were studied. At 38 days of age they were injected with insulin, 0.4 to 1.8 units per day, with bovine growth hormone (250 μUg/day) or with the same amount of growth hormone and epinephrine, 5 to 20 μUg/day, concomitantly, or were untreated until the 49th day of age. Control rats of the same age were either pair-fed to untreated hypophysectomized rats or given an ad libitum diet. Untreated hypophysectomized rats showed poor body weight gain per unit food intake and reduced skeletal growth. The nucleic acid and protein content of liver, muscle, and cerebrum was reduced when compared with controls of the same age. The ratio of protein: DNA (cell size) was increased for body size but reduced for age. Administration of insulin caused hypertrophy of liver cells and increased the protein content of liver, but did not affect muscle and cerebrum. DNA content of liver or cerebrum did not increase, and the gain in DNA content of muscle was not remarkable. There was a definite increase in RNA content of muscle, liver, and cerebrum and in the ratios of RNA: DNA and protein: DNA of liver. Injections of growth hormone caused an increase in DNA (cell number), RNA, and protein content in liver, muscle, and cerebrum. There was a reduction in the ratio of cytoplasm to nucleus. The protein increment was nullified by the injection of epinephrine in conjunction with growth hormone. DNA content of muscle and liver was increased, but not to the level produced by growth hormone alone. The increase in RNA content of liver, muscle, and cerebrum was again significant; the ratio of RNA: DNA increased only in liver. Caloric intake of untreated hypophysectomized rats and those treated with growth hormone or insulin was comparable. Rats injected with epinephrine showed a significant increase in caloric intake. The results indicate that insulin is involved with growth in cell size, while growth hormone is active with respect to the increase in cell number. Both hormones are required for optimal growth. Speculation: The present study indicates that both growth hormone and insulin are required for optimum cell growth. Epinephrine administration retards the increase in cell number that normally occurs in hypophysectomized rats receiving growth hormone. This suggests that overactivity of the sympathetic pathways may retard growth and produce effects that simulate hypopituitarism.

Induction of excessive deoxyribonucleic acid synthesis in Escherichia coli by nalidixic acid.

Prior treatment of Escherichia coli with nalidixic acid in nutritionally complete medium altered the subsequent pattern of deoxyribonucleic acid (DNA) synthesis normally observed in nutritionally deficient medium. Transfer of E. coli 15 TAU to an amino acid- and pyrimidine-deficient medium usually resulted in a 40 to 50% increase in DNA content. Previous treatment with nalidixic acid caused a 200 to 300% increase in DNA content under these conditions. The extent of this DNA synthesis depended on the duration of prior exposure to nalidixic acid. The maximal rate of synthesis was obtained after a 40- to 60-min exposure to nalidixic acid and was two to three times that of the control. The induction of this excessive DNA synthesis was prevented by chloramphenicol or phenethyl alcohol, but the synthesis of this DNA was only partially sensitive to these agents. With E. coli TAU-bar, the rate of DNA synthesis, after removal of nalidixic acid, was similar to that of E. coli 15 TAU, but the maximal amount of DNA synthesized was 180 to 185% of that initially present. Cesium chloride density gradient analysis demonstrated that DNA synthesis after removal of nalidixic acid occurs by a semiconservative mode of replication. The density distribution of this DNA was similar to that obtained after thymine starvation. These results suggest that nalidixic acid treatment may induce additional sites for DNA synthesis in E.coli.

Enzyme Studies in Muscular Dystrophy V

The separate and concurrent effects of nutritional muscular dystrophy, induced by vitamin E-deficiency, and of denervation atrophy on wet weight, noncollagen protein nitrogen and deoxyribonucleic acid content, and on the activities of six acid hydrolases in the hamstring muscles of rabbits have been investigated. There are similarities in the patterns of increased acid hydrolase activity in both conditions, although in nutritional dystrophy the increments are much greater. Loss of muscle mass and noncollagen protein nitrogen content are much greater in denervation atrophy than in nutritional muscular dystrophy, whereas only in the latter condition is there a marked increase in deoxyribonucleic acid content. The effects of both conditions occurring simultaneously appear to be additive. The results also suggest that the increased activities of hydrolytic enzymes represent a common enzymatic mechanism that is involved in the loss of muscle mass and that most of the increments in hydrolase activity of dystrophic muscle originate from the pathological muscle cells themselves and may partially reflect attempts at regeneration.

Growth hormone and mammary gland lobulealveolar development.

The effect of growth hormone on mammary gland lobule-alveolar growth in the ovariectomized rat was studied using deoxyribonucleic acid (DNA) of the abdominal-inguinal glands as an index of the degree of cellular proliferation. The administration of 1 mg growth hormone in combination with 2 µg estradiol benzoate for 19 days resulted in alveolar formation and an increase in mammary DNA content above that resulting from injections of either hormone alone. The mean DNA concentration of glands of rats treated with 2 µg estradiol, 6 mg progesterone, 3 µg/100 g l-thyroxine, and 0.5, 1.0, 1.5, and 2.0 mg growth hormone was significantly greater than that of animals receiving only the estradiol, progesterone, and thyroxine. The increase in the mean DNA content was due to a shift in the range of values to a higher plane and did not result from an elevated DNA in only a few animals. It is suggested that the administration of growth hormone during the growth phase of the mammary gland may have a beneficial effect on the subsequent lactation.