中国油气田开发特征与技术发展

从中国陆上油气田的地质特征出发，系统地阐述了中国油田注水开发的动态变化特征、对策，综合调整方法和技术系列，并分别了阐述了各种特殊类型油气藏。如复杂断块油藏、低渗透砂岩油藏、重质油藏天然气 以及西部沙漠地区新油田的开发特点和技术系列，并且阐述了三次采油提高采收率新技术的进展情况，还提出了今后开发各类油藏，特别是深度开发高含水，高采出程度的老油田的技术发展和研究方向。     

Leptin is a four-helix bundle: secondary structure by NMR

OBJECTIVES: To describe the experience of two male fertility programs using electroejaculation (EEJ) in the management of men with ejaculatory failure secondary to diabetes mellitus. METHODS: Twenty-nine EEJ procedures were performed in 7 diabetic men with ejaculatory failure. Results were reviewed with attention paid to sperm characteristics in both antegrade and retrograde specimens as well as pregnancy rates. RESULTS: Retrograde semen specimens retrieved from the bladder following EEJ contained a mean of 3444.5 million sperm (range 269.2 to 4996 million). Antegrade specimens contained a mean of 698.8 million sperm (range 226.8 to 1961 million). Mean sperm motility was 4% for retrograde specimens (range 0% to 11%) and 7% for antegrade specimens (1% to 15%). In all but 1 case, semen specimens were used for intrauterine insemination. The total number of motile sperm contained in the processed, inseminated specimens ranged from 1 to 87.2 million. In 1 case, the sperm obtained through EEJ was used in an in vitro fertilization procedure. CONCLUSIONS: EEJ can be successfully used to obtain sperm from men with ejaculatory failure due to diabetes mellitus. The procedure requires general anesthesia, and pregnancy rates after intrauterine insemination with the processed sperm are low. Advanced reproductive technologies may offer a feasible alternative, providing higher success rates with fewer procedures.     

Antioxidative and proapoptotic effects of riluzole on cultured cortical neurons

Riluzole is used clinically in patients with amyotrophic lateral sclerosis. As oxidative stress, in addition to excitotoxicity, may be a major mechanism of motoneuron degeneration in patients with amyotrophic lateral sclerosis, we examined whether riluzole protects against nonexcitotoxic oxidative injury. Probably reflecting its weak antiexcitotoxic effects, riluzole (1-30 microM) attenuated submaximal neuronal death induced by 24-h exposure to 30 microM kainate or NMDA, but not that by 100 microM NMDA, in cortical cultures. Riluzole also attenuated nonexcitotoxic oxidative injury induced by exposure to FeCl3 in the presence of MK-801 and CNQX. Consistent with its antioxidative effects, riluzole reduced Fe3+-induced lipid peroxidation, and inhibited cytosolic phospholipase A2. By contrast, riluzole did not attenuate neuronal apoptosis induced by staurosporine. Rather unexpectedly, 24-48-h exposure to 100-300 microM riluzole induced neuronal death accompanied by nuclear and DNA fragmentations, which was attenuated by caspase inhibitor carbobenzyloxy-Val-Ala-Asp-fluoromethyl ketone but not by protein synthesis inhibitor cycloheximide. The present study demonstrates that riluzole has direct antioxidative actions, perhaps in part by inhibiting phospholipase A2. However, in the same neurons, riluzole paradoxically induces neuronal apoptosis in a caspase-sensitive manner. Considering current clinical use of riluzole, further studies are warranted to investigate its potential cytolethal effects.     

The ancestral gene for transcribed, low-copy repeats in the Prader-Willi/Angelman region encodes a large protein implicated in protein trafficking, which is deficient in mice with neuromuscular and spermiogenic abnormalities

Transcribed, low-copy repeat elements are associated with the breakpoint regions of common deletions in Prader-Willi and Angelman syndromes. We report here the identification of the ancestral gene ( HERC2 ) and a family of duplicated, truncated copies that comprise these low-copy repeats. This gene encodes a highly conserved giant protein, HERC2, that is distantly related to p532 (HERC1), a guanine nucleotide exchange factor (GEF) implicated in vesicular trafficking. The mouse genome contains a single Herc2 locus, located in the jdf2 (juvenile development and fertility-2) interval of chromosome 7C. We have identified single nucleotide splice junction mutations in Herc2 in three independent N-ethyl-N-nitrosourea-induced jdf2 mutant alleles, each leading to exon skipping with premature termination of translation and/or deletion of conserved amino acids. Therefore, mutations in Herc2 lead to the neuromuscular secretory vesicle and sperm acrosome defects, other developmental abnormalities and juvenile lethality of jdf2 mice. Combined, these findings suggest that HERC2 is an important gene encoding a GEF involved in protein trafficking and degradation pathways in the cell.     

Identification of fur, aconitase, and other proteins expressed by Mycobacterium tuberculosis under conditions of low and high concentrations of iron by combined two-dimensional gel electrophoresis and mass spectrometry

Iron plays a critical role in the pathophysiology of Mycobacterium tuberculosis. To gain a better understanding of iron regulation by this organism, we have used two-dimensional (2-D) gel electrophoresis, mass spectrometry, and database searching to study protein expression in M. tuberculosis under conditions of high and low iron concentration. Proteins in cellular extracts from M. tuberculosis Erdman strain grown under low-iron (1 microM) and high-iron (70 microM) conditions were separated by 2-D polyacrylamide gel electrophoresis, which allowed high-resolution separation of several hundred proteins, as visualized by Coomassie staining. The expression of at least 15 proteins was induced, and the expression of at least 12 proteins was decreased under low-iron conditions. In-gel trypsin digestion was performed on these differentially expressed proteins, and the digestion mixtures were analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry to determine the molecular masses of the resulting tryptic peptides. Partial sequence data on some of the peptides were obtained by using after source decay and/or collision-induced dissociation. The fragmentation data were used to search computerized peptide mass and protein sequence databases for known proteins. Ten iron-regulated proteins were identified, including Fur and aconitase proteins, both of which are known to be regulated by iron in other bacterial systems. Our study shows that, where large protein sequence databases are available from genomic studies, the combined use of 2-D gel electrophoresis, mass spectrometry, and database searching to analyze proteins expressed under defined environmental conditions is a powerful tool for identifying expressed proteins and their physiologic relevance.     

Domain organization of the 39-kDa receptor-associated protein

The 39-kDa receptor-associated protein (RAP) is an endoplasmic reticulum resident protein that binds to the low density lipoprotein receptor-related protein (LRP) as well as certain members of the low density lipoprotein receptor superfamily and antagonizes ligand binding. In order to identify important functional regions of RAP, studies were performed to define the domain organization and domain boundaries of this molecule. Differential scanning calorimetry (DSC) experiments revealed that the process of thermal denaturation of RAP is highly reversible and occurs in a broad temperature range with two well resolved heat absorption peaks. A good fit of the endotherm was obtained with four two-state transitions suggesting these many cooperative domains in the molecule. A number of recombinant fragments of RAP were expressed in bacteria, and their domain composition and stability were characterized by DSC, circular dichroism, and fluorescence spectroscopy. The results confirmed that RAP is composed of four independently folded domains, D1, D2, D3, and D4, that encompass residues 1-92, 93-163, 164-216, and 217-323, respectively. The first and the fourth domains preserved their structure and stability when isolated, whereas the compact structure of the fragment corresponding to D2 seems to be altered when isolated from the parent molecule. Isolated D3 was partially degraded during isolation from bacterial lysates. The isolated D4 was capable of binding with high affinity to LRP whereas neither D1 nor D2 bound. At the same time a fragment containing both D1 and D2 exhibited high affinity binding to LRP. These facts combined with the thermodynamic analysis of the melting process of the fragments containing D1 and D2 indicate that these two domains interact with each other and that the proper folding of the second domain into a native-like active conformation requires presence of the first domain.     

Divergence in proteins, mitochondrial DNA, and reproductive compatibility across the isthmus of Panama

It is widely believed that gene flow connected many shallow water populations of the Caribbean and eastern Pacific until the Panama seaway closed 3.0 to 3.5 million years ago. Measurements of biochemical and reproductive divergence for seven closely related, transisthmian pairs of snapping shrimps (Alpheus) indicate, however, that isolation was staggered rather than simultaneous. The four least divergent pairs provide the best estimate for rates of molecular divergence and speciation. Ecological, genetic, and geological data suggest that gene flow was disrupted for the remaining three pairs by environmental change several million years before the land barrier was complete.     

Effect of hexachlorocyclohexane on hsp26 expression in transgenic Drosophila melanogaster

The type and amount of lipophilic antioxidants in plasma of hyperlipidemic patients are of great importance since they play a central role in preventing deleterious oxidation of blood lipids and proteins. Isolation and quantitation of lipophilic antioxidants from hyperlipidemic plasma samples meet great obstacles because of increased levels of various intermediary lipid products. This study was designed to develop a rapid and efficient extraction and separation procedure for simultaneous analysis of ubiquinone-9 and -10 as well as alpha-, delta-, and gamma-tocopherol isomers. The levels of ubiquinone-10, alpha- and gamma-tocopherol were analyzed in human plasma samples using high-performance liquid chromatography. Lipid extraction was performed by petroleum ether/methanol/water. After phase separation, ubiquinone was reduced to ubiquinol by sodium borohydride and the lipids were separated on a C18 column. A binary gradient with solvents containing lithium perchlorate was used, and an electrochemical detector was employed for quantitation. This procedure was also efficient for the analysis of antioxidant lipids in samples containing a large number of accumulated and interfering lipid intermediates. Thus, the procedure described here is useful for efficient and rapid quantitation of ubiquinones and tocopherols in human plasma samples, especially those originating from hyperlipidemic patients.