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The interaction of tamoxifen with the rat uterine oestrogen receptor protein has been investigated. The administration of tamoxifen to immature female rats produced a dose-dependent decrease in cytoplasmic oestrogen receptor concentrations and exchange methods were used to demonstrate a rise in nuclear oestrogen receptor concentrations. In immature rat uterine weight tests tamoxifen produced a partial uterotrophic response over a dose range of 0.5–8.0 μg/day and the same doses, administered simultaneously with oestradiol, produced a dose-related inhibition of oestrogen-stimulated uterine wet weight increases and uterine DNA content. Measurement of cytoplasmic oestrogen receptor concentrations during a uterine weight test demonstrated that 4 μg tamoxifen produced significant antiuterotrophic effects without a complete depletion of cytoplasmic oestrogen receptors. A single administration of tamoxifen (4 μg) produced a slow but prolonged rise in uterine wet weight associated with a slow decrease in cytoplasmic oestrogen receptors and a prolonged rise in oestrogen receptor levels in the nucleus. By 24 h cytoplasmic oestrogen receptor concentrations had returned to control levels. After a single dose of oestradiol (0.08 μg) there was a rapid decrease in cytoplasmic oestrogen receptors associated with a rapid rise in uterine wet weight but only a small rise in nuclear oestrogen receptor concentrations. In oestradiol-treated animals neither rises in uterine weight nor nuclear oestrogen receptor concentrations were maintained after 24 h. Oestrogen receptors which were translocated to the nucleus after a large dose of oestradiol (0.9 μg) were in the main salt (0.4 M KC1) extraetable although a small but significant proportion were salt resistant. By comparison oestrogen receptors translocated after tamoxifen were completely salt extractable. It is suggested that the change in the properties of the oestrogen receptor is responsible for the partial agonistic effects of tamoxifen. Since tamoxifen does not have to deny oestrogen binding completely to produce antioestrogenic effects in the uterus, a competition between tamoxifen-oestrogen receptor complexes and oestradiol-oestrogen receptor complexes for nuclear acceptor sites may be the primary antioestrogenic mechanism.     

Extrapineal melatonin: analysis of its subcellular distribution and daily fluctuations

Abstract: We studied the subcellular levels of melatonin in cerebral cortex and liver of rats under several conditions. The results show that melatonin levels in the cell membrane, cytosol, nucleus, and mitochondrion vary over a 24‐hr cycle, although these variations do not exhibit circadian rhythms. The cell membrane has the highest concentration of melatonin followed by mitochondria, nucleus, and cytosol. Pinealectomy significantly increased the content of melatonin in all subcellular compartments, whereas luzindole treatment had little effect on melatonin levels. Administration of 10 mg/kg bw melatonin to sham‐pinealectomized, pinealectomized, or continuous light‐exposed rats increased the content of melatonin in all subcellular compartments. Melatonin in doses ranging from 40 to 200 mg/kg bw increased in a dose‐dependent manner the accumulation of melatonin on cell membrane and cytosol, although the accumulations were 10 times greater in the former than in the latter. Melatonin levels in the nucleus and mitochondria reached saturation with a dose of 40 mg/kg bw; higher doses of injected melatonin did not further cause additional accumulation of melatonin in these organelles. The results suggest some control of extrapineal accumulation or extrapineal production of melatonin and support the existence of regulatory mechanisms in cellular organelles, which prevent the intracellular equilibration of the indolamine. Seemingly, different concentrations of melatonin can be maintained in different subcellular compartments. The data also seem to support a requirement of high doses of melatonin to obtain therapeutic effects. Together, these results add information that assists in explaining the physiology and pharmacology of melatonin.     

Correlation of two methods for determination of cathepsin D in breast carcinoma (immunohistochemistry and ELISA in cytosol)

We have studied the correlation of two methods(immunohistology and ELISA in cytosol) of cathepsin D(CD) determination in breast carcinoma patients. Fifty sixspecimens of tumor tissue were collected consecutively, andCD expression in tumor tissue and tissue macrophageswas determined by standard immunohistochemistry using the aNCL-CDmanti-cathepsin D mouse monoclonal antibody (Novocastra Laboratories Ltd.,Newcastle, UK). Additionally, CD concentration was determined byELISA in cytosol of the same breast carcinomaspecimens. CD positivity was correlated with tumor size,histological grade of tumor, and the cytosol progesteroneand estrogen receptor concentrations. There was no statisticallysignificant correlation between examined parameters and either CDpositivity by immunohistochemistry or cytosol CD concentration. Thecorrelation between CD expression in tumor cells ofbreast carcinoma by immunohistochemistry and cytosol CD positivitywas not found either. However, there was asignificant association between abundance of CD positive stromalmacrophages and cytosol CD concentration in all histologicaltumor types (p < 0.05). CD positive macrophageswere abundant in most of cytosol CD positivespecimens.These results suggest that breast cancer cytosol CDconcentration is the cumulative result of CD contentin both carcinoma cells and stromal macrophages.     

实验性动脉粥样硬化进程中血小板内游离钙[Ca~(2+)]i和cAMP水平相关性分析

食饲2％胆固醇饲料的60只家兔与仅食饲基础饲料的20只家免对比研究发现:随着动脉粥样硬化(AS)的病理进展,血小板内〔Ca~(2+)〕i逐渐增高,峰值在AS晚期cAMP水平最低,而且,两者呈非常密切负相关(r=-0.667,P<0.001)。     

脑血管疾病患者外周红细胞及其胞膜Cu/ZnSOD水平变化的观察

本文报道50名健康人及33例脑血管疾病患者外周红细胞及其胞膜铜锌超氧化物歧化酶Cu/Zn SOD放免测定值。结果表明94％患者红细胞胞液Cu/Zn SOD呈极显著性降低(P<0.001),提示缺血性损伤病理过程中红细胞内超氧阴离子自由基(O(_2~-))产生异常,胞外(O(_2~-))可通过RBC膜阴离子通道进入胞内增多,从而引起胞内SOD歧化作用而耗损增加。本文测定18例脑血栓形成患者红细胞膜Cu/ZnSOD含量未见明显变化(0.2>P>0.1),可能由于细胞间隙胞外SOD(EC-SOD)及RBC膜本身具有防御氧自由基作用有关,从而保护了RBC膜Cu/ZnSOD于平衡状态。本文还就其作用机理作了简要论述。     

Calcium-activated neutral proteinase in rat brain myelin and subcellular fractions

The activity of calcium-activated neutral proteinase (mM CANP) was determined in subcellular fractions of rat brain. The CANP activity in whole homogenate and its membrane fractions including myelin was increased ten-fold following treatment with Triton X-100. The majority of the activity (60%) was in the primary particulate fractions P1 (nuclear), P2 (mitochondrial), and P3 (microsomal). Following subfractionation of each particulate fraction, most of the activity (50%) was found in the myelin-enriched fractions (P1A, P2A, and P3A) and separated at the interface of 0.32-0.85 M sucrose. Only 20-30% of the total homogenate activity was in cytosol. The enrichment in the myelin fractions resembled that for 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) activity. Immunoblotting revealed that the CANP was mainly in myelin and cytosol. In addition to the presence of 72-76 Kd and 80 Kd bands, there were faint high-molecular-weight CANP bands ranging from 110-150 Kd and lower-molecular-weight forms in the region of 30-50 Kd in both purified myelin and cytosol. These studies suggested that CANP is present in myelin and cytosol and that it exists in the brain in membrane-bound and soluble forms.     

The metabolism and N-oxide reduction of olaquindox in liver preparations of rats,pigs and chicken

Olaquindox, N-(2-hydroxyethyl)-3-methyl-2-quinoxalinecarboxamide-1,4-di-N-oxide, is one of the quinoxaline-dioxides used widely as an antimicrobial growth promoter in pig production. Its toxicities were reported to be closely related to the formation of N-oxide reductive metabolites. The present study presents the metabolism and N-oxide reduction of olaquindox incubated with liver microsomes and liver cytosol of rats, pigs and chicken. Metabolites were identified and characterized with a novel LC/MS-ITTOF. Thirteen metabolites were found in liver microsomes of rats, three of which were identified to be novel. Seven metabolites were found in liver microsomes of pigs and chicken. The N-oxide reduction was the major metabolic pathway of olaquindox in liver microsomes of the three species. The N1-reduction of olaquindox to metabolite O2 was found in not only liver microsomes but also cytosol of the three species in the presence of NAD(P)H under hypoxic conditions. The N1-reduction could be inhibited by air and carbon monoxide, and be significantly stimulated by riboflavin under various conditions. The N1-reduction in the liver cytosol of rats and pigs could be enhanced by menadione, but the reduction in liver cytosol of chicken could not be. The N1-reduction activities in all animals were not abolished when liver microsomes and cytosol were boiled. These findings suggested that the N1-reduction of olaquindox could be mediated by non-enzymatic and enzymatic conditions. This N1-reduction of olaquindox could also be catalyzed by a quinone-dependent reducing system in liver cytosol of rats and pigs. Moreover, liver cytosol of rats and pigs had an ability of N4-reduction that catalyzed olaquindox to metabolite O1 in the presence of benzaldehyde under hypoxic conditions, but the liver cytosol of chicken did not. The N4-reduction could be inhibited markedly in the cytosol rats and pigs by menadione, chlorpromazine and promethazine. In addition, 7-hydroxycoumarin was also found to inhibit the formation of O1 in the cytosol of rats. The inhibitory results suggested that the N4-reduction might be catalyzed by aldehyde oxidase in the cytosol of pigs, and by aldehyde oxidase and xanthine oxidase in the cytosol of rats. In conclusion, the N1-reduction and N4-reduction of olaquindox are mediated by multiple mechanisms and significant species differences are involved in both reductions. This work is a contribution to the understanding of toxicities and the relativities between toxicities and metabolism of olaquindox.     

Acceleration of lipid degradation by sericoside of Terminalia sericea roots in Fully differentiated 3T3-L1 cells

Sericoside is a traditional herbal saponin from Terminalia sericea (Family Combretaceae). The influence of sericoside on lipolysis was studied in fully differentiated 3T3-L1 cells, and glycerol release into the cytosol and residual triglyceride were measured. The addition of sericoside stimulated glycerol release into the cytosol from deposited triglyceride in a dose- and time-dependent manner. These data suggested that sericoside has a strong lipolytic activity.     

Superoxide Dismutase As An Index Of Copper, Zinc And Manganese Status

The activity of cytosolic superoxide dismutase (Cu, Zn-SOD), correlates well with other measures of copper status, but it is not affected by zinc deficiency. The activity of the mitochondrial enzyme (Mn-SOD) is expressed by manganese deficiency.     

Age differences in RNA transport through the nuclear membrane

Laboratory of Molecular Biology, Institute of Gerontology, Academy of Medical Sciences of the USSR, Kiev. (Presented by Academician of the Academy of Medical Sciences of the USSR D. F. Chebotarev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 108, No. 10, pp. 445–447, October, 1989.