Neonatal exposure to estradiol prevents the expression of ovarian hormone-induced luteinizing hormone and prolactin surges in adulthood but not antecedent changes in neuropeptide Y or adrenergic transmitter activity: Implications for sexual differentiation of gonadotropin secretion

Sex differences in adult patterns of mating behavior and gonadotropin secretion in rats are determined in part by the presence or absence of gonadal steroids during a perinatal critical period. For example, male rats and female rats exposed neonatally to androgen do not exhibit LH surge patterns when treated appropriately with ovarian hormones in adulthood, and there is evidence that this may be due to a failure of ovarian hormones to activate the hypothalamic neuronal systems that stimulate LH secretion in such animals. Because considerable evidence suggests that estradiol formed centrally from testosterone is responsible for the permanent defeminization of mating behavior and gonadotropin secretion, the present studies compared normal females with normal males and with females treated neonatally with estradiol on the ability of ovarian hormones to induce several important neurochemical changes antecedent to the LH surge, including changes in neuropeptide Y (NPY) and LH-releasing hormone (LHRH) concentrations in the median eminence, as well as changes in turnover rates for catecholamine transmitters in the medial basal hypothalamus and medial preoptic area. Normal ovariectomized female rats responded to sequential treatment with estradiol followed by progesterone with afternoon LH and prolactin (PRL) surges, and with sequential accumulation followed by decline in concentrations of LHRH and NPY in the median eminence prior to the LH surge. In addition, administration of progesterone increased the turnover rates of norepinephrine (NE) and epinephrine (EPI) in the arcuate-median eminence region of normal females. Gonadectomized male rats receiving the same ovarian hormone treatment failed to exhibit LH or PRL surges and displayed none of the changes in neurotransmitter turnover or peptide concentrations characteristically seen in the normal female. Unexpectedly however, when females that were treated with estradiol benzoate on days 1–3 postpartum were ovariectomized and treated with ovarian hormones in adulthood, they showed the same accumulation/decline in median eminence NPY concentrations and the same activation of NE and EPI turnover in the arcuate-median eminence region as normal females, even though they showed no LH or PRL surges or changes in median eminence LHRH concentrations. These results suggest that estradiol may not mediate all of the defeminizing actions of androgen exerted during the early neonatal period, and particularly those actions that result in a lack of responsiveness in central noradrenergic, adrenergic and NPY systems in adulthood. However, an action of neonatal estradiol may result in uncoupling of the LHRH neurosecretory system from normal excitatory neurochemical influences.     

诱导兔骨髓基质细胞向神经干细胞分化的初步实验研究

目的：观察兔骨髓基质细胞体外培养的生长行为及增殖、分化情况，探讨由骨髓分离培养神经干细胞的可行性和有效性。方法：无菌条件下行骨穿术，密度梯度离心分离获取骨髓基质细胞，利用多种增殖、分化诱导因子和神经干细胞培养液进行培养、分化诱导，用免疫细胞化学方法进行鉴定。结朵：骨髓基质细胞在体外培养中能形成NESTIN抗原阳性的细胞克隆团，进一步分化，部分细胞胞体增大并出芽，逐渐发育成为较成熟的长突起细胞，长突起相互连接、交织成网并建立纤维联系。结论：骨髓基质细胞具有较强的自我更新能力和多向分化潜能，易于取材、体外培养和增殖，在一定诱导条件下可以生成神经干细胞。     

三氧化二砷与维甲酸联合作用在NB4,MR2细胞系中的体外研究

目的：观察三氧化二砷(As2O3)和全反式维甲酸(ATRA)联合作用对NB4，MR2不同亚型急性早幼粒白血病细胞株，诱导分化、增殖、凋亡的影响。方法:以NB4，MR2为体外模型，利用细胞生长曲线、台盼蓝拒染法、MTT法、NBT、细胞形态Wrigh‘s-Gimesa染色，观察细胞增殖、分化、凋亡的相互作用。结果：NB4细胞株：0．5μmol/L As2O3与10^-6mol/L ATRA对细胞增殖、分化、凋亡呈现拮抗，而0．5μmol/L As2O3与(10^-7--10^-8mol/L)ATRA呈现协同；MR2细胞株：0．5μmol/L As2O3与10^-6mol/L ATRA对细胞增殖、分化、凋亡呈现协同。结论：As2O3与全反式维甲酸协同效应呈现不同细胞、剂量的特异性，MR2细胞株协同效应明显强于NB4细胞株。     

Liposomal 1,25 (OH)2 vitamin D3 compounds block proliferation and induce differentiation in myelomonocytic leukaemia cells

The vitamin D₃ derived hormone 1,25 (OH)₂ vitamin D₃ (1,25 D₃) is able to induce growth arrest and differentiation in myelomonocytic leukaemia cells. In order to allow for specific delivery to leukaemic cells the lipophilic compound was incorporated into the lipid membranes of liposomes. Liposomal 1,25 D₃ reduced proliferation as measured by ³H-thymidine incorporation in HL60 leukaemia cells by up to 60%. When liposomes were prepared at different concentrations of 1,25 D₃ 65% inhibition was achieved at 48 n M . The MC 1288 stereoisomer of 1,25 D₃ was more potent and had the same activity at 48 n M .
The effect of the liposomal compounds was specific to myeloid cells as they reduced proliferation in myelomonocytic HL60, monoblastic U937 and monocytic Mono Mac 6 cells but not in the T-cell lines Jurkat and Molt 4.
The antiproliferative effect of liposomal 1,25 D₃ was associated with an induction of differentiation since treated HL60 cells showed a monocytic morphology, increased expression of CD14 and decreased expression of CD33.
When peripheral blood leukaemic cells from M4 and M5 acute myeloid leukaemia (AML) patients were admixed with liposomal compounds an antiproliferative effect was seen in all five cases, including the two cases where free compounds led to enhanced growth. Liposomal delivery of 1,25 (OH)₂ vitamin D₃ may offer a novel approach to treatment of myelomonocytic leukaemia.     

HMBA诱导MEC—1细胞分化角蛋白染色的变化

用六亚甲基二乙酰胺（ＨＭＢＡ）作为分化诱导剂，对人粘液表皮样癌细胞系ＭＥＣ－１细胞中角蛋白进行染色，结果发现高分子量角蛋白在被诱导细胞中含量明显增高。分光光度仪检测角蛋白含量，诱导组ｘ±ｓ为２１８±５１，对照组为１４９±４７，两组有显著差异（Ｐ＜００１），这可能与细胞分化有关。     

Depriving neonatal rats of milk from early lactation has long-term consequences on mammotrope development

The sudden appearance of prolactin-releasing cells during the early postnatal period of the rat is initiated by a small milk-borne peptide. Depriving newborn rats of this early milk factor severely retards mammotrope differentiation during the neonatal period. In the present work, we extend our study of early milk deprivation to the adult. To this end, newborn litters were crossfostered onto mothers that had given birth the same day or one week earlier in order to deprive pups in the latter group of early milk. At 5, 15, and 30 d of age, rats deprived of such milk had decreased percentages of mammotropes (as measured by reverse hemolytic plaque assay, RHPA) when compared to nondeprived animals (P<0.05). By 45 d, the percentage of mammotropes was similar for the two crossfostered groups (P>0.1) and this persisted through d 60. Subsequently, we assessed the secretory capacity of mammotropes from 60-d old rats to secretagogues and found that early milk deprivation had no effect on basal prolactin release (P>0.1), but that it augmented hormone secretion evoked by thyrotropin-releasing hormone (TRH, 100 nM; P<0.01). The inhibitory response to dopamine (DA; 1 μM) and the stimulatory response to angiotensin II (AGII; 100 nM) were not altered by early milk deprivation (P>0.1). Taken together, these results demonstrate that factors in milk from early lactation are required for normal mammotrope differentiation, and that the delay induced by early milk deprivation leads to altered secretory function of mammotropes in adult animals.     

甲状腺机能亢进症辨证分型与甲皱微循环及TT_3、TT_4、FT_4I和吸~(131)碘率的关系

对甲状腺机能亢进症(甲亢)患者进行了临床辨证分型,同步观察甲皱微循环及检测TT_3 TT_4 FT_4I、吸~(131)碘率,探讨它们之间的关系。结果表明甲亢患者微循环积分明显高于对照组(P<0.01),但不同类型甲亢的血淤情况亦不相同。心肝火旺型的微循环积分低于气滞痰凝型和血瘀型,但TT_3、TT_4、FT_4I明显增高;气滞痰凝型居中;血淤型的微循环积分明显增高,但TT_3、TT_4、FT_4I低于其他两型。吸~(131)碘率三型间无差异(P>0.05)。     

60Coγ射线对体外培养成骨细胞作用的实验研究

目的：研究放射性骨损伤的发病机制，探讨骨折合并射线损伤愈合能力下降的原因。方法：将体外培养的成骨细胞用^60Coγ射线一次性照射3、6、9、12Gy，以建立体外培养成骨细胞受射线作用的实验模型；同时，观察成骨细胞的碱性磷酸酶（ALP）活性改变，骨形态发生蛋白（BMP）和转化生长因子β1（TGF-β1）的胞质内表达量，以及细胞内钙离子的含量。结果：成骨细胞受射线照射后，其ALP活性明显降低，且与照射剂量呈明显量效关系，3Gy组抑制率为31.59%，而12Gy组则为84.95%；BMP、TGF-β1的表达量下降，但与照射剂量无明显量效关系；胞质内钙含量亦降低，但受照各组间的抑制率无明显统计学差异。结论：射线对成骨细胞具有直接损害作用，放射性骨损伤的重要方面就是射线对成骨细胞的主要功能酶ALP活性的损害，抑制BMP、TGF-β1等生长因子的合成，且干扰细胞内第二信使钙离子，从而致骨组织的再生重建机能下降。     

Neuronal migration and dendritic maturation of the medial cerebellar nucleus in rat embryos: an HRP in vitro study using cerebellar slabs

The morphological maturation of medial nuclear neurons of fetal rat cerebella was studied using an in vitro assay. Neurons of this nucleus were identified in isolated preparations of rhombencephalon between embryonic days 16 and 20 (E16-E20) by the intracerebellar decussation of their outgrowing axons within the uncinate fascicle. A small crystal of horseradish peroxidase (HRP) applied either in the region containing the inferior cerebellar peduncle or, preferably, in the lateral cerebellum retrogradely labeled contralateral medial nuclear neurons. In the youngest embryos (E16-E17), HRP-marked neurons were situated rostrally at the dorsal surface of the cerebellum. By E18, the cell mass containing labeled neurons had shifted in a rostrocaudal and dorsoventral direction and finally reached the adult position in E19-E20 embryos. Dendritic differentiation of these neurons followed a similar positional gradient, closely corresponding to the pattern of temporal development. From the most immature monopolar forms located dorsally to the virtually adult stellate neurons in a ventral position, it was possible to trace a continuum of intermediary forms grouped into six well-defined stages. Immature monopolar cells first became transversely bipolar. Then, they changed orientation, assuming a longitudinal radial direction. During this stage, neurons sank into the cerebellar parenchyma. As they reached their final destination, these neurons gradually developed dendrites which radiated from the cell body in an adult-like pattern. It is concluded that the medial nuclear neurons occupy a superficial dorsal position in early phases of cerebellar ontogeny, thereafter undergoing a second, inward migration. The main stages of neuronal dendritic differentiation occur between E16 and E20, indicating that the ingrowth of afferent in puts to the medial nucleus most probably occurs rather early and is concomitant with dendritic development.