Establishment of a transgenic mouse model specifically expressing human serum amyloid A in adipose tissue

Obesity and obesity co-morbidities are associated with a low grade inflammation and elevated serum levels of acute phase proteins, including serum amyloid A (SAA). In the non-acute phase in humans, adipocytes are major producers of SAA but the function of adipocyte-derived SAA is unknown. To clarify the role of adipocyte-derived SAA, a transgenic mouse model expressing human SAA1 (hSAA) in adipocytes was established. hSAA expression was analysed using real-time PCR analysis. Male animals were challenged with a high fat (HF) diet. Plasma samples were subjected to fast protein liquid chromatography (FPLC) separation. hSAA, cholesterol and triglyceride content were measured in plasma and in FPLC fractions. Real-time PCR analysis confirmed an adipose tissue-specific hSAA gene expression. Moreover, the hSAA gene expression was not influenced by HF diet. However, hSAA plasma levels in HF fed animals (37.7±4.0 µg/mL, n = 7) were increased compared to those in normal chow fed animals (4.8±0.5 µg/mL, n = 10; p<0.001), and plasma levels in the two groups were in the same ranges as in obese and lean human subjects, respectively. In FPLC separated plasma samples, the concentration of hSAA peaked in high-density lipoprotein (HDL) containing fractions. In addition, cholesterol distribution over the different lipoprotein subfractions as assessed by FPLC analysis was similar within the two experimental groups. The established transgenic mouse model demonstrates that adipose tissue produced hSAA enters the circulation, resulting in elevated plasma levels of hSAA. This new model will enable further studies of metabolic effects of adipose tissue-derived SAA.     

Restoration of Atlantic sturgeon in the northeastern USA with special emphasis on culture and restocking

Stocks of anadromous Atlantic sturgeon ( Acipenser oxyrhynchus ) on the east coast of the United States are severely depleted due to past over-fishing and habitat loss and degradation. All commercial fisheries for this species are now closed and several state and federal agencies are investigating the use of cultured fish for stock replenishment. A breeding and stocking protocol was developed to address genetic concerns and to provide guidance for culture programs.
Several thousand 3-month old cultured fingerling sturgeon were stocked in the Hudson River, New York, in 1994. Based on mark-recapture techniques, juvenile recoveries in 1995 and 1996 indicated that wild production was very weak in that river. In 1996, several thousand cultured and marked yearling sturgeon were stocked in the Nanticoke River in Maryland. Over the next 10 months, these fish grew well and became distributed throughout the Chesapeake Bay in Maryland and Virginia. The amount of useful information gained from these two examples of using cultured Atlantic sturgeon suggests a broader potential role. Without active intervention, such as a long-term commitment to using cultured fish, some sturgeon stocks on the U. S. Atlantic Coast may be lost.     

Enzymatic formation of intermediates in the biosynthests of ajmalicine: Strictosidine and cathenamine

Pre-purified enzymes isolated from Catharanthus roseus suspension cultures synthesize strictosidine and cathenamine from tryptamine and secologanin. Whereas strictosidine showed metabolic activity, cathenamine accumulates during the cell-free incubations in the absence of reduced pyridine nucleotides. In the presence of δ-d-gluconolactone (0.1 M), strictosidine accumulates in a yield of ca 50%. Optimum conditions for its accumulation in crude extracts were found to be at pH 4.1, 0.25 mM tryptamine and 1.25 mM secologinin. Strictosidine synthase is stable for more than 1.5 months at 4°. The optimum conditions for the enzymatic synthesis of cathenamine are 1.54 mM tryptamine and 7.7 mM secologanin at pH 7.5. In the presence of NH₄⁺ the formation of the latter alkaloid decreases due to the synthesis of unidentified compounds.     

Cytoplasmic thioredoxin reductase is essential for embryogenesis but dispensable for cardiac development

Two distinct thioredoxin/thioredoxin reductase systems are present in the cytosol and the mitochondria of mammalian cells. Thioredoxins (Txn), the main substrates of thioredoxin reductases (Txnrd), are involved in numerous physiological processes, including cell-cell communication, redox metabolism, proliferation, and apoptosis. To investigate the individual contribution of mitochondrial (Txnrd2) and cytoplasmic (Txnrd1) thioredoxin reductases in vivo, we generated a mouse strain with a conditionally targeted deletion of Txnrd1. We show here that the ubiquitous Cre-mediated inactivation of Txnrd1 leads to early embryonic lethality. Homozygous mutant embryos display severe growth retardation and fail to turn. In accordance with the observed growth impairment in vivo, Txnrd1-deficient embryonic fibroblasts do not proliferate in vitro. In contrast, ex vivo-cultured embryonic Txnrd1-deficient cardiomyocytes are not affected, and mice with a heart-specific inactivation of Txnrd1 develop normally and appear healthy. Our results indicate that Txnrd1 plays an essential role during embryogenesis in most developing tissues except the heart.     

Phylogenetic relationships of the tribe Paini (Amphibia, Anura, Ranidae) based on partial sequences of mitochondrial 12s and 16s rRNA genes

Partial sequences of mitochondrial 12S and 16S rRNA genes from 19 Asian frog species of the tribe Paini (Ranidae, Dicroglossinae) allowed a first molecular study of the phylogenetic relationships of this tribe. This analysis confirmed that this tribe is a monophyletic group, but suggested relationships did not agree with previous generic classification of this clade based on morphology. Two major clades were recognized within the Paini. For one of them, the generic name Quasipaa is available. Phylogenetic relationships within the other group are not yet fully clarified and need further study.     

The influence of a cellular size distribution on NMR diffusion measurements

In the magnetic resonance community, the usefulness of diffusion-weighted imaging is undisputed. However, the correct interpretation of multicomponent diffusion is not widely agreed upon, and progress in this direction is impeded by several confounding experimental results. It is thus of great importance to resolve possible interfering factors. The objective of the present study is to examine the influence of a cellular size distribution. Using the Kärger equations, numerical calculations show that even substantial cellular size variations induce only small changes in the estimated compartmental diffusion constants and volume fractions.     

Reliability of the Amplicor internal control to disclose false-negative Chlamydia trachomatis PCR results

Four possibly false-negative samples were detected when 514 male urine specimens were tested in the Amplicor Chlamydia trachomatis assay. In three of the four samples, the inhibition could be reduced by removal of urine supernatant. Under partially inhibitory conditions, after spiking with 50 C. trachomatis elementary bodies/ml specimen, a selective inhibition of the C. trachomatis target amplification and a preferential internal control amplification was observed. We conclude that a positive internal control signal might be misleading in inhibitory specimens with low amount of C. trachomatis.     

An evaluation of the in vitro cytotoxicities of 50 chemicals by using an electrical current exclusion method versus the neutral red uptake and MTT assays

According to the 2001 National Institutes of Health guidance document on using in vitro data to estimate in vivo starting doses for acute toxicity, the performance of the electrical current exclusion method (ECE) was studied for its suitability as an in vitro cytotoxicity test. In a comparative study, two established in vitro assays based on the quantification of metabolic processes necessary for cell proliferation or organelle integrity (the MTT/WST-8 [WST-8] assay and the neutral red uptake [NRU] assay), and two cytoplasm membrane integrity assays (the trypan blue exclusion [TB] and ECE methods), were performed. IC50 values were evaluated for 50 chemicals ranging from low to high toxicity, 46 of which are listed in Halles Registry of Cytotoxicity (RC). A high correlation was found between the IC50 values obtained in this study and the IC50 data published in the RC. The assay sensitivity was highest for the ECE method, and decreased from the WST-8 assay to the NRU assay to the TB assay. The consistent results of the ECE method are based on technical standardisation, high counting rate, and the ability to combine cell viability and cell volume analysis for detection of the first signs of cell necrosis and damage of the cytoplasmic membrane caused by cytotoxic agents.