Lead inhibits 1,25-dihydroxyvitamin D-3 regulation of calcium metabolism in osteoblastic osteosarcoma cells (ROS 17/2.8)

We have determined the dose-response of 1,25-dihydroxyvitamin D-3 (1,25-(OH)₂D₃) on the intracellular free calcium-ion concentration ([Ca²⁺¹]_i) in the osteoblastic osteosarcoma cells, ROS 17/2.8, using ¹⁹F-NMR and the intracellular divalent cation indicator, 1,2-bis(2-amino-5-fluorephenoxy)ethane-N, N, N′, N′-tetraacetic acid (5F-BAPTA). The dose-response demonstrated an inverted U-shaped relationship with maximal elevation of [Ca²⁺]_i at doses of 1 to 10 nM 1,25-(OH)₂D₃. At 10 nM, 1,25-(OH)₂D₃ elevated the [Ca²⁺]_i from a control level of 118±4 nM to a peak value of 237±8 nM within 40 min. 1,25-(OH)₂D₃ also increased the intial rate of Ca²⁺ influx into ROs 17/2.8 cells, measured by ⁴⁵Ca uptake, with a dose-response relationship which paralleled its effects on [Ca²⁺]_i. Treatment of ROS 17/2.8 cells with Pb²⁺ at 1 and 5 μM significantly increased [Ca²⁺]_i but significantly reduced the 1,25-(OH)₂D₃-induced elevation of [Ca²⁺]i. Simultaneous treatment of naive cells with 1,25-(OH)₂D₃ and Pb²⁺ produce little reduction of 1,25-(OH)₂D₃ and Pb²⁺ produce little reduction of 1,25-(OH)₂D₃-induced ⁴⁵Ca uptake while 40 min treatment with Pb²⁺ before addition of 1,25-(OH)₂D₃ significantly reduced the 1,25-(OH)₂D₃-induced increase in ⁴⁵Ca influx. These findings suggest that Pb²⁺ acts by inhibiting 1,25-(OH)₂D₃-activation of Ca²⁺ channels and interferes with 1,25-(OH)₂D₃ regulation of Ca²⁺ metabolism in osteoblastic bone cells.     

Psychosexual milestones in women prenatally exposed to diethylstilbestrol

Thirty women aged 17 to 30 years with a record-confirmed history of prenatal exposure to diethylstilbestrol (DES) were compared to 30 women of similar age and demographic background with a history of abnormal Pap smear findings. Heterosocial and heterosexual histories were assessed by systematic semistructured interviews. The groups differed neither in the age at menarche nor in the age at attainment of various psychosexual milestones.     

Chronic administration of three neuroleptics: Effects of behavioral supersensitivity mediated by two different brain regions in the rat

This investigation assessed the relative abilities of three neuroleptics to supersensitize behaviors mediated by the nigrostriatal and mesolimbic dopamine (DA) systems. Rats were treated with either haloperidol, thioridazine, fluotracen or vehicle for 21 days. Stereotypy, in response to DA injection to the striatum, or locomotor activity, in response to DA injection to the nucleus accumbens, were measured after the termination of drug treatment. Pre-treatment with haloperidol enhanced both behavioral responses to central DA injection, while pre-treatment with thioridazine did not enhance either behavior. Pre-treatment with fluotracen enhanced the locomotor response to DA injection to the nucleus accumbens, but did not alter stereotypy after DA injection to the striatum. Neuroleptics differ in their ability to supersensitize the same DA-related behavior, and act selectively to supersensitize behaviors mediated by different DA systems.     

The role of choline phospholipids in hypertonic cryohemolysis

Hemolysis resulting from a warm-to-cold temperature shift in a Hypertonie environment (hypertonic cryohemolysis) is studied with the use of phospholipases as membrane probes of the phospholipids of the outer leaflet of the bilayer. Bee venom phospholipase A₂ which attacks only phosphatidylcholine (PC) in the intact erythrocyte results in inhibition of cryohemolysis produced by both hypertonic sodium chloride and sucrose. In both cases, about 25% of the loss of PC occurs before any such inhibition, suggesting the possibility of functionally separate domains of PC in the outer leaflet of the bilayer. Sphingomyelinase also attacks only sphingomyelin in the intact erythrocyte and results in inhibition of cryohemolysis due to hypertonic sodium chloride but not of that due to sucrose. In each case, inhibition of the enzymatic hydrolysis by EDTA abolished the effect on cryohemolysis. It is postulated that cryohemolysis is inhibited when phosphylipid interaction with membrane (cytoskeletal) proteins are abolished, but present knowledge of membrane structure does not permit a detailed mechanism to be proposed.     

Conjugation in Tetrahymena thermophila: A temporal analysis of cytological stages

The time course and synchrony of the stages of conjugation in Tetrahymena thermophila as defined by cytologically observable changes in the morphology and position of the nuclei were established. The time required for 50% of the pairs to enter or pass a particular stage, as well as the duration of each stage were determined. The relative synchrony of the pairs as they went through conjugation was followed by correlating the maximum percentage of the population found in a stage with the duration of that stage. The degree of synchrony between the pairs was found to be high under the conditions of this study, with very little decrease in synchrony seen during the initial 9 h of conjugation. Although some variability in the degree of synchrony was seen between different matings, there was little change detected in the duration of each cytological stage. Prolonged starvation of the cells prior to their mating resulted in a gradual loss of synchrony.     

Respective role of superoxide and hydroxyl radical in the activity of the reconstituted microsomal ethanol-oxidizing system.

Superoxide dismutase, a scavenger of O^?₂. does not affect the rate of ethanol oxidation in a reconstituted system containing purified cytochrome P-450, NADPH-cytochrome c reductase, and dilauroyl l-3-phosphatidyl choline. The same concentration of Superoxide dismutase (50 μg/ml) completely abolishes the oxidation of epinephrine in this reconstituted system and ethanol oxidation by the xanthine-xanthine oxidase. Ethanol is not oxidized by the reconstituted system when NADPH is replaced by H₂O₂ but the addition of H₂O₂ to this sytem containing NADPH accelerates ethanol oxidation. This increase is abolished by the addition of Superoxide dismutase. Hydroxyl radical scavengers (50 mm dimethylsulfoxide, 100 mm benzoate, 100 mm mannitol, 20 mm thiourea) diminish the oxidation of ethanol in the reconstituted system by 48 to 76%. Thus hydroxyl radical may participate in the activity of reconstituted ethanol-oxidizing system, whereas Superoxide is not involved.     

Effects of diverse androgens on the sexual behavior and morphology of castrated male quail

Castrated male Japanese quail were injected for 15 days with 1 mg/day of testosterone propionate (TP), testosterone (T), androstenedione (AE), androsterone (AO), 5α-dihydrotestosterone benzoate (5α-DHTB), or 5β-dihydrotestosterone (5β-DHT), or with oil. Copulation was activated to a significant extent only by TP and T. Strutting was activated only by TP, T, and AE. Proctodeal (foam) glands were well-developed in birds injected with TP, T, AE, or 5α-DHTB. Additional data were obtained following implantation of pellets of crystalline T, AE, AO, or 5α-DHT. T pellets activated copulation, but AO and 5α-DHT pellets did not. Effects of AE require further study. These results suggest that conversion of androgen to estrogen is necessary for the activation of copulation in the male quail.     

铜绿假单胞菌NY3胞外分泌物对降解烃类的影响作用

为了研究铜绿假单胞菌Pseudomonas aeruginosa NY3胞外分泌物对烃类降解的作用,对胞外分泌物影响烃类降解的效率进行了研究。研究发现,NY3菌以LB培养基和以烃类为唯一碳源的无机盐培养基培养得到的种子液,离心并洗涤菌体后,菌细胞代谢烃类效率明显下降。分别利用盐析和溶剂萃取法,提取种子液上清液中胞外大分子和小分子,且投加在NY3菌(离心后的菌细胞)降解十四烷的无机盐培养基中,发现24 h内外加胞外大分子化合物,使NY3菌对十四烷去除率可提高约14%,而投加小分子化合物使NY3菌24 h内对十四烷去除率提高约6%。利用SDS-page聚丙烯酰氨凝胶电泳分离胞外大分子,结果发现主要是该菌胞外所分泌的蛋白或多肽类,主要有3个条带,它们的分子量约在35~55 k D范围内,其对烃降解促进作用机理有待进一步验证。利用飞行质谱(LCMS-IT-TOF)鉴定胞外小分子分泌物,结果表明在本研究条件下,它们均为氧化还原反应活性物,可以加快反应体系中电子传递速度,促进底物的氧化还原反应。     

2H2O effect on the electron and proton flow in isolated chloroplasts. An indication for lateral heterogeneity of membrane pH

To determine how the actual pH on the membrane surfaces regulate the redox reactions, a study of the electron and proton flow in thylakoids was made in heavy water, in which ²H⁺ has a smaller mobility than ¹H⁺. The decrease of the redox rates by ²H₂O is stronger in coupled than in uncoupled conditions, although the bulk ΔpH is slightly diminished; therefore changing ¹H⁺ by ²H⁺ enhances the electron transfer control. This is particularly so when the two systems are linearly connected: i.e. the plastoquinone pool, not the water-splitting complex, is the main point of the redox chain regulation by ΔpH and of the deuterium action. The role of the proton diffusion barriers is emphasized and the concept of a heterogeneity—accentuated in ²H₂O - of the pH along the membrane is proposed. The corresponding local pH , different at the points of H⁺ active translocation and passive leakage, would be the real factors controlling the membrane-bound processes.