Effects of interferons and interleukin 2 on natural killing of cytomegalovirus-infected fibroblasts

The ability of nonadherent peripheral blood mononuclear cells of normal individuals to lyse noninfected and cytomegalovirus (CMV)-infected human fibroblasts was enhanced by preincubation with recombinant human alpha interferon (alpha-rIFN) or beta (beta-rIFN). In contrast, recombinant human gamma IFN (gamma-rIFN) augmented natural killing (NK) against both targets relatively poorly. Recombinant or natural human interleukin 2(IL-2) also augmented NK against noninfected and CMV-infected targets. Augmentation of NK by IFN or IL-2 could be blocked by the addition of corresponding antisera. IL-2-enhanced NK against CMV-infected targets was usually independent of alpha-IFN production.

Requirement for HLA-DR+ accessory cells in natural killing of cytomegalovirus-infected fibroblasts

The role of HLA-DR+ cells in NK activity against CMV-infected FS4 foreskin fibroblasts and K562 erythroleukemia cells was examined. When nonadherent PBMC were depleted of either HLA-DR+ or Leu-11b+ cells by treatment with mAbs plus C, NK activity against CMV-FS4 target cells was markedly reduced. In contrast, depletion of HLA-DR+ cells had no effect on NK activity against K562 target cells. When HLA-DR-depleted cells were added to Leu-11b-depleted cells, NK activity against CMV-FS4 was restored. Negative selection experiments indicated that the HLA-DR+ cells contributing to NK activity against CMV-FS4 are not B or T cells, while negative and positive selection experiments excluded a role for monocytes. Experiments in which HLA-DR- and Leu-11b- cells were mixed in varying proportions indicated that NK(CMV-FS4) is mediated by Leu-11b+ cells, while HLA-DR+ cells provide an accessory function. Irradiation (50 GY) abolished the NK effector function of Leu-11b+ cells, but not the accessory function of HLA-DR+ cells. The NK activity against CMV-FS4 of HLA-DR- cells was restored by the addition of rIFN-alpha or of cell-free supernatants generated by coculturing PBMC or Leu-11b- cells with CMV-FS4. The ability of these supernatants to restore NK activity of HLA-DR- cells was completely abrogated by the addition of neutralizing amounts of antibody to IFN-alpha. In related experiments, neutralization of IFN-alpha in NK assays had little or no effect on NK activity against CMV-FS4, suggesting that the accessory function of HLA-DR+ cells might be mediated by alternative mechanisms in addition to the secretion of extracellular IFN-alpha.

Interleukin 2 enhances natural killing of varicella-zoster virus-infected targets

Preincubation of peripheral blood non-adherent mononuclear cells with purified or recombinant interleukin 2 (IL-2) significantly enhanced natural killer (NK) activity against uninfected and varicella-zoster virus (VZV)-infected targets, while antibody-dependent cellular cytotoxicity (ADCC) against VZV-infected targets was not increased. Preincubation of effector cells with IL-2 had no effect on conjugate formation, but lysis of both targets was increased in single cell assays. IL-2-enhanced NK against VZV-infected targets was independent of gamma-interferon (gamma-IFN) production.

Thyroid hormone regulation of beta-adrenergic receptors and catecholamine sensitive adenylate cyclase in foetal heart

The effect of thyroid hormone on the beta-adrenergic receptor in foetal cardiac membranes was analysed by measuring the binding of (-)[3H]DHA. The specific activities (per mg protein) of beta-adrenergic receptors decreased with advancing gestational age, whereas the total activities (per heart) increased under the similar conditions. The change in the binding affinities was not statistically significant. 1; 3,5,3'-L-triiodothyronine (T3) stimulated the (-)[3H]DHA binding capacities of the cardiac membranes of foetuses of all age groups. The enhancement in the receptor activity was completely inhibited actinomycin D or cycloheximide. The contents of epinephrine, norepinephrine and cAMP increased with advancing gestational age; but T3 had no significant effect on the catecholamines or cAMP. Similarly, the activities of the basal, NaF stimulated and Gpp(NH)p stimulated adenylate cyclase remained unaltered by T3, but the activities increased progressively with foetal maturity. The absolute values of catecholamine stimulated adenylate cyclase activities in the hearts of T3 treated foetuses were, however, higher compared to those in the untreated foetuses. The enhancement of the activities were totally blocked by the action of actinomycin D, cycloheximide or propranolol. Our results indicate that thyroid hormone enhances the number of beta-adrenergic receptor binding sites by synthesizing new receptor proteins resulting in increased catecholamine sensitivity.

Potentiation of surfactant release in fetal lung by thyroid hormone action

Thyroid hormone has been shown to accelerate fetal lung development, but the mechanisms by which this hormone acts are yet unknown. Since this hormone may act indirectly by potentiating the action of endogenous catecholamines, we studied this mechanism by measuring beta-adrenergic receptors in fetal lung. Fetal rabbits at 27 days of gestation were treated with triiodothyronine (T3), 100 micrograms/100 g, in the presence and absence of propranolol, 200 micrograms/100 g, or actinomycin D, 20 micrograms/100 g. Fetuses were killed by decapitation either after 4 or 24 h of T3 treatment. The beta-adrenergic antagonist l-[3H]dihydroalprenolol was used to directly estimate the number and affinity of beta-adrenergic receptor in lung membranes. T3 increased the number of beta-adrenergic receptors in fetal lung, but the affinity of binding did not change. The enhancement of binding capacity after 4 h of T3 treatment was not inhibited by actinomycin D. However, 24-h T3-mediated stimulation was partially blocked by actinomycin D. In addition, T3 stimulated the catecholamine content, adenylate cyclase activity, and adenosine 3',5'-cyclic monophosphate content of lung. T3 increased the lecithin-to-sphingomyelin ratio, phosphatidylglycerol, and disaturated phosphatidylcholine content of the pulmonary lavage fluid. These parameters were completely inhibited by propranolol after 4 h and partially inhibited by actinomycin D after 24 h. Thus thyroid hormone enhances lung maturation by increasing the number of beta-adrenergic receptors in fetal lung.

Antitumor activity with nontoxic doses of protein A

This report confirms our previous observation that IV inoculation of purified protein A causes regression of rat mammary adenocarcinomas. In treated tumors, we have obtained histological evidence of changes indicating tumor cell destruction. Protein A treatment does not cause reduction in the body weight or organ weights of rats; nor does it cause any decrease in activity of the enzymes of the microsomal mixed function oxidase system in the liver. Protein A stimulates peripheral white cell counts in normal rats, but not in tumor-bearing rats. We found that protein A infusion reduced (P less than 0.0005) the level of circulating plasma immune complex concentration. A homing study with 125I-labeled protein A indicated that liver, spleen, and kidney tissues are the major sites of protein A accumulation. Therefore, protein A seemed to exert its antitumor effects without causing any generalized toxicity to the system. It is postulated that the action of protein A may be related to its ability to cause a drastic reduction in circulating plasma immune complex concentration, thus potentiating the immune reactivity of the host observed earlier.

A new laboratory method for evaluating the relative solubility and erosion of dental cements

A method for accelerating the dissolution and erosion of 'acidic' dental cements has been developed which gave relative solubilities in accordance with in vivo observations, in contrast to the conventional test. It involves subjecting 24-h-old specimens to a jet of dilute acid (lactic or citric) and determining weight loss. The relative ranking for 'acidic' cements in the apparatus and in vivo was: glass ionomer less than silicophosphate less than zinc phosphate less than polycarboxylate. The method was not valid for reinforced zinc oxide/eugenol/EBA cements. Of the two polycarboxylate cements studied, a brand which has the acid in the powder was found to be more soluble than the conventional material. It is proposed that the method be the basis of a new solubility/erosion test in national and international standards for 'acidic' dental cements.

Hematological changes produced in mice by ochratoxin A and citrinin

The effect of 6 weekly injections of ochratoxin A (5 mg/kg) and citrinin (20 mg/kg) on the following hematological indices of mice was studied: erythrocyte sedimentation rate, hematocrit percentage, mean corpuscular values, red cell indices, platelet count, total count of bone marrow cells, differential count of bone marrow cells, total count of splenic cells, spleen weight, and serum calcium. These mycotoxins resulted in a significant decrease in platelet count and hematocrit values. On the other hand, they increased erythrocyte sedimentation rate, mean corpuscular values and red cell indices. Weight of the spleen and the splenic cell count decreased significantly in ochratoxin A and citrinin treated mice. Total count of bone marrow cells, erythrocyte precursors, leucocyte precursors and megakaryocyte precursors of femoral bone marrow decreased significantly in toxin treated mice. Calcium concentration in the serum of toxin treated mice also was decreased significantly.

A study of the volumetric setting shrinkage of some dental materials

The setting reaction of six dental materials has been studied by using a water dilatometer at 25 degrees and 37 degrees C. Where there is no water absorption during the test, the method gives reproducible values of the setting shrinkage and at the same time shows a clear physical picture of the entire setting process. This method is suitable for adaptation as a specification test for setting shrinkage and has good potential for being used as a supplementary or substitute test for initial and final set times.

Hematological changes produced in mice by Nuvacron or Furadan

The effects of multiple intraperitoneal doses of Nuvacron (0.8 mg/kg) or Furadan (0.25 mg/kg) on hematological values in mice were studied. The following were measured: clotting time, hemoglobin content, total count of red blood cells and white blood cells, differential count of white blood cells, platelet count, erythrocyte sedimentation rate, hematocrit value, mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration, bone marrow and splenic measurements. These pesticides caused a significant decrease in hemoglobin content, total count of red blood cells, platelet count, erythrocyte sedimentation rate and hematocrit value. The administration of Nuvacron or Furadan prolonged the clotting time and caused an increase in total count of white blood cells. Among white blood cells, there was an increase in neutrophils and basophils and a fall in the count of lymphocytes in treated animals. Bone marrow depression and splenic hyperplasia were observed in mice after administration of the pesticides.

Ovarian steroidogenesis and development of fetuses following ochratoxin A treatment in pregnant rats

Administration of ochratoxin A to pregnant rats from 6 to 12 days of gestation period, resulted in complete resorption of fetuses. On histological examination luteal degeneration was observed along with reduction in the weight of corpus luteum (mg/100 mg ovarian tissue) and pituitary gland. The enzyme delta 5-3 beta-hydroxy steroid dehydrogenase (delta 5-3 beta-OHD) and glucose-6-phosphate dehydrogenase were demonstrated histochemically in the ovary of pregnant rats. The activities of the enzymes were suppressed significantly in ochratoxin A treated rats. The same treatment also resulted in an accumulation of cholesterol and ascorbic acid in the ovary. Based on these results, it is suggested that resorption of fetuses in ochratoxin A treated rats may be related with a diminution in ovarian steroidogenesis possibly due to reduction in pituitary gonadotrophin secretion.

Histochemical determination of adrenal steroidogenesis in rat after treatment with ochratoxin A

The enzymes delta 5-3 beta-hydroxy steroid dehydrogenase and glucose-6-phosphate dehydrogenase were demonstrated histochemically in the adrenal cortex of female rats. The activities of these enzymes were increased significantly in ochratoxin A treated rats along with an increase in the weight and reduction in cholesterol and ascorbic acid content of the gland. The observations suggest that after treatment with ochratoxin A, adrenal steroidogenesis was stimulated.

Onset of puberty and ovarian steroidogenesis following administration of ochratoxin A

The present experimental design was set up to examine the effect of Ochratoxin A on the onset of reproductive maturity and the ovarian steroidogenic capacity by means of histochemical studies. Ochratoxin A treatment causes a remarkable delay in sexual maturation as evidenced by the age at vaginal opening and appearance of first estrus (cornifid smear). The same treatment also results in a significant diminution of the delta 5-3 beta-hydroxysteroid dehydrogenase and glucose-6-phosphate dehydrogenase activity along with a reduction in the weight of ovary, uterus, and pituitary. On the basis of above data it is assumed that the probable cause of delayed maturation in Ochratoxin A treated rat is due to the suppressed ovarian steroidogenesis.