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Results for “Modifiable factors”

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PubMedDate not supplied

[Long-term effects of sublethal radiation doses and modifying factors on the state of immunological indices in mice].

A study was made of mean life, amount of CFUs and plaque-forming cells, and functional activity of T-lymphocyte subpopulations in CBA mice a year after irradiation with a dose of 3 Gy and a single therapeutic administration (after 4-5 h) of bone marrow and thymus cells, or after shielding of femur during exposure. The effects obtained after irradiation at different dose-rates (0.031 and 1.29 mA/kg) have been compared.

Animals↗
PubMedDate not supplied

Effect of certain factors modifying the lipid-mobilizing activity in vitro in the serum of rats during hypothermia.

The serum of hypothermic animals shows in vitro the ability of mobilizing fatty acids from the adipose tissue. This ability is quantitatively comparable to the lipolytic activity of glucagon but is lower than that of adrenaline. Propranolol decreases the lipid-mobilizing activity in the serum of hypothermic animals in vitro. Similarly insulin added to the medium with the serum of hypothermic animals decreased the lipid-mobilizing activity.

Adipose Tissue↗
PubMed1984

Dietary carbohydrate level as a modifying factor of 3'-methyl-4-dimethylaminoazobenzene liver carcinogenesis in rats.

The effect of dietary carbohydrate (CHO) level on liver carcinogenesis induced by 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) was investigated in male Wistar rats. In the first experiment, three groups of 30 rats were maintained on liquid diets, which differed only in the level of CHO (sucrose); high-CHO (14.04 g/day), medium-CHO (9.72 g/day) and low-CHO (3.64 g/day). Half of the animals from each group were given 3'-Me-ADB added to their diet at the level of 10 mg/day/rat for 20 weeks, the remainder being maintained as carcinogen-free controls. Final body and liver weights of control rats decreased with decreasing dietary level of CHO, while carcinogen treatment increased the liver/body weight ratio with decreasing CHO level. Quantitative analysis showed that the number and area of liver tumors per unit area of liver sections increased with decreasing dietary sucrose level. Hepatocellular carcinomas were only observed in rats placed on the low-CHO diet (4 out of 15 rats). In the second experiment, where rats were given 3'-Me-DAB in a semisynthetic powder diet for 16 weeks, the number and area of gamma-glutamyltranspeptidase-positive foci were significantly higher in the low-CHO diet group, with decreasing values being associated with increase in sucrose level in the diet. Thus, the present experiments clearly showed that lowered CHO intake enhanced, whereas high intake reduced, 3'-Me-DAB liver carcinogenesis in rats.

Animals↗
PubMed1984

Ankle and knee position as a factor modifying intracompartmental pressure in the human leg.

The objective of this study was to examine the effect of position of the knee and ankle on intracompartmental pressures in the leg. Slit catheters were introduced bilaterally into all four muscle compartments of the lower extremities of six healthy volunteers. Intracompartmental pressures were monitored with the catheters while the ankle joint was passively held in full dorsiflexion, full plantar flexion, or neutral with the knee flexed 90 or 10 degrees or fully extended. Statistical analysis revealed that intracompartmental pressure increased significantly in all four compartments when the ankle was passively dorsiflexed. Pressure in the superficial posterior and lateral compartments was dependent on knee position and in the deep posterior and anterior compartments it was independent of knee position. In addition, pressure in the deep posterior compartment decreased significantly when the ankle was placed in full plantar flexion, and that finding was independent of knee position. Anterior compartment pressure was not significantly elevated by full passive plantar flexion of the ankle.

Adult↗
PubMed1983

Modifying factors in pancreatic carcinogenesis in the hamster model. I. Effect of protein-free diet fed during the early stages of carcinogenesis.

The role of protein in pancreatic carcinogenesis was examined in outbred Syrian golden hamsters treated with the pancreatic carcinogen N-nitrosobis(2-oxopropyl)amine (BOP) and fed a purified protein-free diet (PPFD). The PPFD was fed for 28 days from 8 weeks of age; before and after animals were fed PPFD, they were given a commercial diet (CD). BOP was given before PPFD feeding (group 1) or at 18 days (group 2) and 28 days (group 3) from the beginning of the PPFD feeding. BOP-treated control hamsters (group 4) were pair-fed a purified control diet (PCD) instead of PPFD. All animals fed PPFD and PCD were returned to a CD for the rest of the experiment, which was terminated in each group 52 weeks after BOP treatment. The results showed a highly significant reduction of tumor incidence (P less than 0.0001) in hamsters that received PPFD, when compared to those fed PCD, regardless of the time of carcinogen administration during the dietary regimen. Hamsters treated with BOP at 18 days of PPFD (group 2) developed neither benign nor malignant pancreatic tumors. The inhibition of pancreatic neoplasms was not related to reduced calorie consumption, since this occurred in the BOP-treated hamsters that were pair-fed the PCD diet. The results indicated that both the initiation and promotion of pancreatic carcinogenesis with BOP in hamsters can be inhibited by lack of protein in the diet given for 4 weeks during the early stages of the neoplastic process.

Animals↗
PubMed1983

Modifying factors in pancreatic carcinogenesis in the hamster model. IV. Effects of dietary protein.

The possible effects of dietary protein on pancreatic cancer induced in outbred Syrian golden hamsters by N-nitrosobis(2-oxopropyl)amine (BOP) were studied. Three levels of casein as protein at low [LP = 9 g/385 kilocalories (kcal)], medium (MP = 18 g/385 kcal), or high levels (HP = 36 g/385 kcal) were fed in two sequences to 4 groups of hamsters. The effects of protein level on the initiation phase of BOP carcinogenesis were examined in hamsters fed LP or HP from 3 through 7 weeks of age, followed by MP for the remainder of their lives. The role of protein level on the promotional (developmental) phase of carcinogenesis was evaluated in hamsters fed (from 3 through 7 wk of age) MP, followed by LP or HP for the rest of their lives. One-half of the hamsters from each of the 4 groups received a single sc BOP injection (10 mg/kg body wt) at 8 weeks of age. Changes in diet from one type to the other occurred 2 days after BOP treatment. An MP diet fed before and after BOP served as the experimental control diet. The results demonstrated that the LP diet inhibited the developmental phase of carcinogenesis only in females, whereas the MP and HP diets did not affect initiation or promotion of cancer in either sex. The inhibitory effect of the LP diet in pancreatic carcinogenicity only in females calls for further studies.

Animals↗
PubMed1983

T lymphocytes modifying factors in sera of patients with Myasthenia gravis.

The examination of patients with Myasthenia gravis revealed that before thymectomy the number of T and B cells in the peripheral blood did not deviate from the norm. It was also observed that their sera contained factor stimulating T lymphocytes to the spontaneous rosette formation, theta antigen generation in xynogeneic system and hydrocortisone-resistant thymocytes. No factor inhibiting the spontaneous rosette formation by T lymphocytes or causing the transmission from Thy-1.2+ cells to Thy-1.2-cells was detected in these sera. Thymectomy resulted in the immediate fall of T lymphocytes number in the peripheral blood of the patients examined. Besides, serum of most patients almost totally lost the stimulating factor. The fall of T cells number did not involve the appearance of the inhibitory factor in the patients' serum. Different than in others results gave blood and serum analysis in the patient tymectomized 10 years earlier. Her blood contained the normal number of T and B lymphocytes and the stimulatory factor of a "limited" activity. It displayed only the ability of generating hydrocortisone-resistant cells, it appeared nonactive in generating theta antigen or restoring the ability of rosette formation by T cells.

Adolescent↗
PubMed1983

Factors modifying the synergistic toxicity of deoxycytidine in combination with thymidine plus 5-fluorouracil in HeLa cells.

We reported previously that deoxycytidine (CdR) enhances the cytotoxic effects of the drug combination thymidine (TdR) plus 5-fluorouracil (FUra) against HeLa S-3 cells. We have now examined the relationships between the concentration of CdR and its cytotoxic and cytokinetic effects, and have also investigated the role of certain other components of the culture medium in this phenomenon. Cell survival was determined by a colony-forming assay; cytokinetic effects were monitored by flow cytometry. In the initial experiments, cells were grown in Ham's F12 medium and exposed for 22 hr to 4 mM TdR, 0 X 025 mM FUra, and dCyd ranging from 1 microM to 4 X 0 mM. The individual drugs were at most only slightly toxic under these conditions; for TdR plus FUra, the survival decreased to 50% (in 5% FCS), and in the three-drug combination it varied from 8% at 1 microM CdR to 28% at 0 X 10 mM and back to a low of 3% at 4 X 0 mM CdR. Results from flow cytometry appeared correlated with the survival data, in that cells accumulated in the S phase to a greater extent in the region around 0 X 10 mM CdR than at higher or lower concentrations. When cells were exposed to the drugs in MEM medium in place of F12, their sensitivity to FUra and the TdR-FUra combination was enhanced, although the additional synergistic effect of CdR was reduced. We found that hypoxanthine, present in F12 but not in MEM, was the principal compound responsible for the observed differences between media.

Cell Survival↗