α‐ketoglutarate delays age‐related fertility decline in mammals

The fecundity reduction with aging is referred as the reproductive aging which comes earlier than that of chronological aging. Since humans have postponed their childbearing age, to prolong the reproductive age becomes urgent agenda for reproductive biologists. In the current study, we examined the potential associations of α‐ketoglutarate (α‐KG) and reproductive aging in mammals including mice, swine, and humans. There is a clear tendency of reduced α‐KG level with aging in the follicle fluids of human. To explore the mechanisms, mice were selected as the convenient animal model. It is observed that a long term of α‐KG administration preserves the ovarian function, the quality and quantity of oocytes as well as the telomere maintaining system in mice. α‐KG suppresses ATP synthase and alterations of the energy metabolism trigger the nutritional sensors to down‐regulate mTOR pathway. These events not only benefit the general aging process but also maintain ovarian function and delay the reproductive decline. Considering the safety of the α‐KG as a naturally occurring molecule in energy metabolism, its utility in reproduction of large mammals including humans deserves further investigation.     

Optimal Sequence of Irinotecan and Oxaliplatin-Based Regimens in Metastatic Colorectal Cancer: A Population-Based Observational Study

The optimal sequence of irinotecan and oxaliplatin-based regimens for metastatic colorectal cancer remains unclear. We conducted a population-based observational study by retrospectively reviewing records from Taiwan’s National Health Insurance Research Database to explore this issue. Patients aged ≥20 years with metastatic colorectal cancer newly diagnosed between 2004 and 2008 (n = 9490) were enrolled in current study. Among these 9490 patients, 3895 patients (41.04%) did not receive any chemotherapy within the first three months after catastrophic illness registration. Patients who received best supportive care were older and had higher Charlson comorbidity indexes and incidences of comorbidities than those who received irinotecan-based regimens, oxaliplatin-based regimens, and 5-fluorouracil/capecitabine alone. Patients who received irinotecan followed by oxaliplatin-based regimens and those who received the reverse sequence were further stratified into arm A (n = 542) and arm B (n = 1156), respectively. The median first time to next treatment was not significantly different between arm A and arm B (210 days vs. 196 days; p = 0.17). However, the median second time to next treatment was longer in arm A than in arm B (155 days vs. 123 days; p = 0.006), which translated into a better overall survival (487 days vs. 454 days; p = 0.02). The crossover rate was higher in arm A than in arm B (47.84% vs. 41.61%; p<0.001). Multivariate Cox regression analyses showed that overall survival was comparable between the two chemotherapy sequences (p = 0.27). Our study suggested that irinotecan followed by oxaliplatin-based regimens might be a better chemotherapy treatment option for metastatic colorectal cancer than the reverse sequence given the higher crossover rate and potential overall survival benefit.     

The androgen-dependent mouse seminal vesicle secretory protein IV: characterization and complementary deoxyribonucleic acid cloning

Seminal vesicle secretory protein IV of a mouse has been isolated, and the cDNA coding for its mRNA has been cloned and sequenced. The 556-nucleotides encode 16 amino acid signal peptides and 92 residues of mature protein. Considerable homology between mouse and rat SVS IV cDNA was found. In the leader peptide and 3'-noncoding region there is 92% and 85% homology, respectively. The other regional homologies are 86% for the first 12, 68.5% for the last 35, and 40% for the middle 44 amino acids. The expression of mouse SVS IV mRNA is under the control of androgen. Administration of testosterone to castrated mice resulted in induction of the mRNA level to 50% of the mature male in 96 h of hormone treatment. Secretion of the protein after testosterone injection follows a similar pattern.     

Modulation of apolipoprotein B antigenic determinants in human low density lipoprotein subclasses

To investigate the effect of low density lipoprotein (LDL) heterogeneity on the conformation of LDL apolipoprotein B (apo-B), the immunoreactivities of 6 monoclonal antibodies against LDL apo-B were measured in 3 LDL subfractions isolated by equilibrium density gradient ultracentrifugation. To ensure a broad range of LDL particles, the LDL subfractions were prepared from normal subjects and patients with hyperapobetalipoproteinemia. With 3 of the antibodies, 1D1, 5E11, and 3A10, LDL fractions 1 (the most buoyant), 2 (the intermediate), and 3 (the densest) were equally immunoreactive and competed similarly with reference whole LDL. In contrast, with 3 other antibodies, 2D8, 3F5, and 4G3, fraction 1 was significantly more reactive than fraction 3; that is for each in turn, 290, 250, and 150% more of the densest LDL protein was required to achieve the same displacement as with fraction 1. Further, the immunoreactivities of the 3 LDL fractions with antibodies 2D8, 3F5, and 4G3 were negatively correlated with their LDL cholesterol to LDL protein ratio with r values of 0.727, 0.898, and 0.870, respectively, suggesting that as LDL particle size decreases, the conformation of the LDL apo-B changes progressively. It is of interest that the antigenic determinants recognized by 3F5 and 4G3 are close to the LDL receptor recognition site on LDL apo-B. Therefore, it is possible that the reduced immunoreactivity of these determinants in dense LDL may be the in vitro correlate of the reduced fractional catabolics rate of dense LDL compared to buoyant LDL previously observed in vivo.     

A chemical and enzymological account of the multiple forms of human liver aldehyde dehydrogenase. Implications for ethnic differences in alcohol metabolism

Three major low-pI zones of aldehyde dehydrogenase (aldehyde:NAD+ oxidoreductase, EC 1.2.1.3) may be visualized with specific histochemical staining after starch gel electrophoresis at pH 7.4 of Caucasian human liver extracts, whereas about 50% of Chinese human liver extracts show only two such zones. The three zones of activity were purified to apparent homogeneity from Caucasian liver. The substrate specificity of each form was investigated by double reciprocal plots using 13 aldehydes of various chemistries. The acetaldehyde-preferring isozyme I lacking in 50% of Chinese livers had a slightly lower native and subunit molecular weight than the "universal' isozymes IIa and IIb. All forms were highly sensitive to disulfiram inhibition. This inhibition could be protected against, or reversed, by dithiothreitol. 2,2'-Dithiodipyridine was a slower inhibitor of isoenzyme I. All three purified forms of the enzyme, as well as crude extracts of normal and isozyme I-deficient Chinese livers, showed positive immunoreactivity to antibodies prepared in rabbits against type I enzyme. Tryptic peptide maps of forms IIa and IIb were almost identical, whereas that of form I, although showing some similarities, was clearly different. These results provide a consistent explanation for the acetaldehyde-mediated extreme sensitivity to moderate alcohol ingestion shown normally by about 50% of oriental subjects and during disulfiram (Antabuse) therapy by all subjects.     

Common denominators in the etiology and pathology of visceral lesions of cystic fibrosis and Keshan disease

The common denominator of a unique disseminated multi-focal milliary myocardial hyaline necrosis and fibrosis in Keshan disease (KSD) and cystic fibrosis (CF) and a commonality of the affected age groups of fetuses and preschool children led to the review of existing KSD autopsy material to search for pancreatic and hepatic lesions considered pathognomonic for CF. Pancreatic lesions considered pathognomonic for CF were found in 595, or 35% of 1700 documented cases of KSD. The pancreatic lesions were limited to tissues of fetuses and preschool children. Adults dying of KSD had diagnostic lesions limited to the cardiovascular system, liver, and skeletal muscle. Varying degrees of focal biliary cirrhosis were identified in 850, or 50% of the KSD autopsies, and 85, or 5% developed severe lobular cirrhosis. The common denominator in CF and KSD appears to be a primary or induced secondary selenium deficiency in age-susceptable humans, prenatally at or around 22 wk of fetal life, during early postnatal life, or during the rapid-growth preschool years. The basic difference between the natural history of CF and KSD is that the selenium deficiency is totally environmental in KSD and appears to be the result of a maternal malabsorptive syndrome or an abnormality of selenium transfer in CF.     

质粒YRP7的基本特性鉴定

质粒YRP7用氯霉素法扩增,碱变性裂解法提取,酸酚法及核糖核酸酶纯化后,得到了高产量(5.6mg/L培养液),高纯度(A260:A280=2.0)的质粒制品,经转化实验及酶切分析确定YRP7具有下列特征:大小为5.41±0.10kb,可赋予宿主细胞AmP~r、Tet~r的表型,对大肠杆菌C600的转化频率为10~(-6)、转化效率为1.5×10~6转化子/mgDNA。限制性内切酶BamH Ⅰ、ECoRⅠ、Hind Ⅲ及PstⅠ在其分子上的切点数分别为1、2、2、2,并确定了各酶切片段的分子大小,对BanHⅠ的单切点,经插入失活法证实其位于Tet~r的基因上。由上述特征可确定,质粒YRP7是一个比较理想的克隆载体。     

无色素腺棉籽蛋白粉与棉子油的制备

低棉酚棉籽为高蛋白含油的植物资源,适宜于水溶法制备油及蛋白粉,出油率一般可达９５％。