Reversibility of spermine-induced intestinal maturation in the rat

In the present investigation, the reversibility of spermine-induced precocious intestinal maturation was studied. Neonatal rats received either saline or spermine (4 mol, twice daily) solution orally on the 11th and 12th postnatal day. They were killed on the 13th, 14th, 15th, 16th, and 17th postnatal days. After the small bowel was removed, it was either divided into three equal parts or prepared for electrophoretic analysis. Histological examination, protein content measurement, and disaccharidase activity estimation were performed on each part of the intestine. Spermine administration was shown to induce structural and mucosal enzyme changes characteristic of postnatal maturation. This phenomenon, which was generally clearly observed in 13- and 14-day-old rats, then became less apparent in 15- and 16-day-old animals. Differences were noted according to the segment of intestine or the biochemical parameter analyzed. When rats were 17 days old, no significant differences generally existed between control and spermine-treated rats. If the 140-to 150-kDa proteins, isolated by electrophoresis, are assumed to represent the subunits of the sucrase-isomaltase complex, the results obtained indicate that spermine induces a modification of the concentration of this complex. When compared to values obtained in adult rats, the concentration of the complex was approximately three times higher in spermine-treated 13-day-old rats, while no differences were found in spermine-treated 14-day-old rats. Further, similar concentrations were found in control and spermine-treated rats with an age of 17 days. These results suggest that spermine-induced precocious intestinal maturation is reversible when spermine treatment is stopped.This work was supported by grants from the F.R.S.M. (number 3.4535.88) and from la Loterie Nationale (1987).     

Evaluation of short‐TE 1H MRSI for quantification of metabolites in the prostate

Back‐to‐back ¹H MRSI scans, using an endorectal and phased‐array coil combination, were performed on 18 low‐risk patients with prostate cancer at 3 T, employing TEs of 32 and 100 ms in order to compare metabolite visualization at each TE. Outer‐volume suppression of lipid signals was performed using regional saturation (REST) slabs and the quantification of spectra at both TEs was achieved with the quantitation using quantum estimation (QUEST) routine. Metabolite nulling experiments in an additional five patients found that there were negligible macromolecule background signals in prostate spectra at TE = 32 ms. Metabolite visibility was judged using the criterion Cramér–Rao lower bound (CRLB)/amplitude < 20%, and metabolite concentrations were corrected for relaxation effects and referenced to the data acquired in corresponding water‐unsuppressed MRSI scans. For the first time, the prostate metabolites spermine and myo‐inositol were quantified individually in vivo, together with citrate, choline and creatine. All five metabolite visibilities were higher in TE = 32 ms MRSI than in TE = 100 ms MRSI. At TE = 32 ms, citrate was visible in 99.0% of lipid‐free spectra, whereas, at TE = 100 ms, no metabolite simulation of citrate matched the in vivo peaks. Spermine, choline and creatine were visualised separately in 30.4% more spectra at TE = 32 ms than at TE = 100 ms, and myo‐inositol in 72.5% more spectra. T₂ values were calculated for spermine (53 ± 16 ms), choline (62 ± 17 ms) and myo‐inositol (90 ± 48 ms). Data from the TE = 32 ms spectra showed that the concentrations of citrate and spermine secretions were positively correlated in both the peripheral zone and central gland (R² = 0.73 and R² = 0.43, respectively), and that the citrate content was significantly higher in the former at 64 ± 22 mm than in the latter at 32 ± 16 mm (p = 0.01). However, lipid contamination at TE = 32 ms was substantial; therefore, to make clinical use of the greater visualisation of prostate metabolites at TE = 32 ms rather than at TE = 100 ms, three‐dimensional MRSI at TE = 32 ms with effective lipid suppression must be implemented. ©2014 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd.     

Skin polyamine levels in psoriasis: the effect of dithranol therapy.

Concentrations of putrescine, spermidine and spermine were determined in biopsies of skin of eight control subjects and of uninvolved skin and skin lesions of eight psoriatic patients before and after topical therapy with dithranol. Mean spermidine and spermine concentrations in uninvolved skin of psoriatic patients were normal, but putrescine concentration was elevated. In psoriatic skin lesions all three amines were significantly elevated. Chemotherapy effectively reduced polyamine concentrations in involved skin touards normal. This decrease in polyamine levels correlated with reduction of the proliferative activity of the epidermis and with clinical improvement of the patients.     

右旋糖苷衍生物纳米粒对人乳腺癌细胞的转染作用研究

目的以右旋糖苷为起始反应物制备对人乳腺癌细胞具有高转染活性的右旋糖苷衍生物纳米粒非病毒基因载体。方法先将右旋糖苷40与高碘酸钠以不同的配比进行反应,生成醛基含量不同的氧化右旋糖苷;氧化右旋糖苷与精胺以不同的配比反应,共生成9种右旋糖苷衍生物纳米粒;以绿色荧光蛋白基因为报告基因、mda-mb-435人乳腺癌细胞为转染细胞,考察9种合成物的基因转染活性,从中选出转染活性最高的生成物。结果高碘酸钠与右旋糖苷40按摩尔比为0.8∶1反应生成氧化右旋糖苷;该氧化右旋糖苷再与精胺按1∶1的摩尔比继续反应,生成的终产物的转染效率最高。结论制备出了对mda-mb-435人乳腺癌细胞具有高转染活性的右旋糖苷衍生物纳米粒非病毒基因载体。     

精胺对某些tRNA熔融曲线和熔融温度的影响

应用纯化的牛肝ｔＲＮＡＩｌｅ和酵母ｔＲＮＡＰｈｅ观察精胺对ｔＲＮＡ熔融曲线和熔融温度的影响。结果显示：在２ｍｍｏｌ／Ｌ精胺存在下，ｔＲＮＡ的吸光度（Ａｂｓ）随温度上升而下降，呈现“低色效应（ｈｙｐｏｃｈｒｏｍｉｓｍ）”和“反Ｔｍ（ｒｅｖｅｒｓｅＴｍ）”现象。本文认为精胺可与ｔＲＮＡ结合，遮掩ｔＲＮＡ分子对２６０ｎｍ紫外光的吸收，保护ｔＲＮＡ分子二级结构。实验亦观察了Ｍｇ２＋＋和Ｋ＋对ｔＲＮＡ熔融曲线和熔融温度的影响。     

正交试验优选非病毒基因载体的制备条件

目的:优选聚阳离子化合物非病毒基因载体的制备条件,制备优良的基因载体.方法:正交试验法,以生成物的伯胺基含量为考察指标,以反应物的浓度、反应物的比例、反应时间、反应物的加入速度为考察因素,每个因素取3个水平.结果:影响因素为反应物比例、反应物的浓度、反应物的加入速度、反应时间.结论:本实验所确立的制备条件可制备出较好的基因载体,且重复性好.     

Modulation of protein synthesis in a cell-free system derived from rat brain by corticotropin (ACTH), magnesium,and spermine

Modulation of protein synthesis by fragments of the ACTH molecule has been studied in a cell-free system obtained from subcortical brain tissue of rats. Both the activity of the protein-synthesizing system and its sensitivity to ACTH-like peptides appeared to be highly dependent on the Mg²⁺ and spermine concentrations. At optimal Mg²⁺ concentrations (4 mM) the peptide sequences ACTH(1–24) and (11–24) were both inhibitory, the latter being the more active. The inhibitory effect was reduced or abolished at higher (suboptimal) Mg²⁺ concentrations. Spermine, like ACTH, inhibited protein synthesis at the optimal Mg²⁺ concentration. However, at lower Mg²⁺ concentrations spermine had a stimulatory effect and maximal activity was obtained at 0.75–1.0 mM Mg²⁺. In the presence of spermine (60 μM) and Mg²⁺ (0.75 mM), a half-maximal inhibition of protein synthesis was obtained with a peptide concentration of 5 μM. A structure-activity study showed that the peptides ACTH(7–16)-NH₂, (11–24), (5–18, ¹⁷Lys¹⁸Lys)-NH₂ and (15–24) were active in inhibiting protein synthesis, whereas the fragments ACTH(1-16)-NH₂ and (17–24) were inactive. The results are discussed in terms of an interaction between ACTH, Mg²⁺, and spermine, and intracellular processes involved in protein synthesis.