The prevalence and related factors of depressive symptoms among junior college nursing students: a cross-sectional study.

Nursing students have particularly experienced stressful lives during nursing education. This cross-sectional study aimed to investigate depressive symptoms and related factors in junior college nursing students. A total of 625 nursing students from a junior college in Taiwan were assessed by Pittsburgh Sleep Quality Index, Adolescent Depression Inventory, Situational Anxiety Scale and the Taiwanese-Chinese version of Stress in Nursing Students Scale. The results showed that (1) the prevalence of depressive symptoms among junior college nursing students was 32.6%; (2) depressive symptoms are significantly related to grade point average, interest in nursing, interest in their clinical placement, career planning after graduation, overeating as a stress-relief strategy, sleep problems, stress, and anxiety; and (3) anxiety, sleep quality, and stress are three major variables that can significantly predict depressive symptoms. Psychological factors may influence young nursing students' willingness to seek assistance from teachers. These factors should be considered when designing strategies to promote their emotional health and well-being. Nursing educators can plan appropriate strategies tailored to junior college nursing students' problems and needs, which thereby may facilitate learning experience and prevent depressive symptoms.

In vivo gene transfer to the mouse nasal cavity mucosa using a stable cationic lipid emulsion.

We evaluate a new cationic emulsion as a mucosal gene carrier and elucidate the relationship between the transfection efficiency and the stability of the carrier/DNA complex. A cationic lipid emulsion was formulated with soybean oil and 1,2-dioleoyl-sn-glycero-3-trimethylammonium-propane (DOTAP) as major components and was used to transfer genes to the epithelial cells of the mouse nasal cavity via intranasal instillation. Correlation between the transfection efficiency and the stability of the carrier/DNA complex was investigated by measuring the carrier size changes and by observing the degree of DNA protection against DNase I digestion in the presence of heparin. The cationic emulsion showed at least 3 times better transfection activity than the liposomal carriers in nasal mucosae. The cationic emulsion was stable in the presence of heparin whereas the liposomal carriers became very unstable. Unlike DNA in liposome/DNA complexes, DNA in the emulsion/DNA complex was resistant to heparin exchange and DNase I digestion. The cationic emulsion was more effective in delivering DNA to nasal mucosae than commercially available liposomal carriers. The transfection activities of the lipid carriers in nasal cavity mucosae are in agreement with the stability of the lipid carriers and their complexes with DNA.

Expression, purification, characterization and crystallization of flap endonuclease-1 from Methanococcus jannaschii.

A gene coding for a protein homologous to the flap endonuclease-1 (FEN-1) was cloned from Methanococcus jannaschii, overexpressed, purified and characterized. The gene product from M. jannaschii shows 5' endo-/exonuclease and 5' pseudo-Y-endonuclease activities as observed in the FEN-1 in eukaryotes. In addition, Methanococcus jannaschii FEN-1 functions effectively at high concentrations of salt, unlike eukaryotic FEN-1. We have crystallized Methanococcus jannaschii FEN-1 and analyzed its preliminary character. The crystal belongs to the space group of P2(1) with unit cell dimensions of a = 58.93 A, b = 42.53 A, c = 62.62 A and beta = 92.250. A complete data set has been collected at 2.0 A resolution using a frozen crystal.

Identification and antioxidant activity of novel chlorogenic acid derivatives from bamboo (Phyllostachys edulis).

One known and two novel antioxidant compounds have been isolated from bamboo (Phyllostachys edulis). The butanol-soluble extract of the bamboo leaves was found to have a significant antioxidant activity, as measured by scavenging the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and the superoxide anion radical (O(2)(-)) in the xanthine/xanthine oxidase assay system. Antioxidant activity-directed fractionation of the extract led to the isolation and characterization of three structural isomeric chlorogenic acid derivatives: 3-O-(3'-methylcaffeoyl)quinic acid (1), 5-O-caffeoyl-4-methylquinic acid (2), and 3-O-caffeoyl-1-methylquinic acid (3). Compounds 2 and 3 were isolated and characterized for the first time from the natural products. In the DPPH scavenging assay as well as in the iron-induced rat microsomal lipid peroxidation system, compounds 2 (IC(50) = 8.8 and 19.2 microM) and 3 (IC(50) = 6.9 and 14.6 microM) showed approximately 2-4 times higher antioxidant activity than did chlorogenic acid (IC(50) = 12.3 and 28.3 microM) and other related hydroxycinnamates such as caffeic acid (IC(50) =13.7 and 25.5 microM) and ferulic acid (IC(50) = 36.5 and 56.9 microM). Among the three compounds, compound 1 yielded the weakest antioxidant activity, and the DPPH scavenging and lipid peroxidation inhibitory activity (IC(50) = 16.0 and 29.8 microM) was lower than those of chlorogenic and caffeic acids. All three compounds exhibited both superoxide scavenging activities and inhibitory effects on xanthine oxidase. Their superoxide anion (O(2)(-)) scavenging activities (IC(50) = 1, 4.3 microM; 2, 2.8 microM; and 3, 1.2 microM) were markedly stronger than those of ascorbic acid (IC(50) = 56.0 microM), alpha-tocopherol (IC(50) > 100 microM), and other test compounds, although their inhibition effects on xanthine oxidase may contribute to the potent scavenging activity. alpha-Tocopherol exerted a significant inhibitory effect (65.5% of the control) on superoxide generation in 12-O-tetradecanoylphorbol-13-acetate-induced human promyelocytic leukemia HL-60 cells, and compound 3 showed moderate activity (36.0%). On the other hand, other compounds including 1, 2, chlorogenic acid, and other antioxidants were weakly active (24.8-10.1%) in the suppression of superoxide generation.

Formulation of defined media for carbon monoxide fermentation by Eubacterium limosum KIST612 and the growth characteristics of the bacterium.

Phosphate-buffered (PBBM) and carbonate-buffered (CBBM) basal media were used in the formulation of defined media for the cultivation of Eubacterium limosum KIST612 with carbon monoxide (CO) as the sole energy source. The bacterium was adapted to the minimal media by sequential passage in media containing casamino acids and those containing ammonium chloride in the place of yeast extract. Biological growth was slower with a lower growth yield in the defined minimal media than in PBBM or CBBM. More butyrate was produced in phosphate-buffered media than in carbonate-buffered media. The bacteria grew without any organic nitrogen in the presence of trace quantities of biotin and pantothenic acid. Anaerobic digester fluid stimulated bacterial growth.

Re-evaluation of 5-fluorouracil as a single agent for gestational malignant trophoblastic neoplasms.

Large doses of 5-fluorouracil, administered by slow intravenous drip, have proven to be very effective in the treatment of malignant trophoblastic tumors. From 1964 through 1975, 5-fluorouracil was used as a single chemotherapeutic agent in 173 cases of invasive mole and 139 cases of choriocarcinoma. This series of patients was further divided into Group A (212 cases) in which 5-fluorouracil was used as initial therapy, and Group B (100 cases) in which 5-fluorouracil was given to those who developed resistance to 6-mercaptopurine and/or to methotrexate. The overall remission rate in Group A patients was 98.4% for invasive mole and 93.0% for choriocarcinoma. In Group B patients the corresponding remission rate was 93.6% and 71.7%, respectively, indicating that 5-fluorouracil is effective in patients who develop resistance to other antimetabolic agents. The rate of recurrence among 213 patients achieving complete remission during follow-up was 1.4% (3 cases). All of the remaining 210 patients had survived for more than 5 years up to the end of 1981, and 96 patients (45.7%) had survived for more than 10 years. In comparison with other antimetabolites, 5-fluorouracil has the advantages of being more effective and less toxic, and can be administered through multiple routes. Therefore, it has remained the agent of first choice in the chemotherapy of malignant trophoblastic neoplasms.

Reevaluation of 5-fluorouracil as a single therapeutic agent for gestational trophoblastic neoplasms.

Large dosage of 5-fluorouracil given by slow intravenous infusion has proved to be very effective in the treatment of gestational trophoblastic neoplasms. From 1965 through 1975, 5-fluorouracil was used as a single chemotherapeutic agent in 173 cases of invasive mole and 139 cases of choriocarcinoma. Complete remission was achieved in 84.9% of cases of invasive mole and in 59.3% of cases of choriocarcinoma when 5-fluorouracil was used as the initial treatment. Seven recurrences with three deaths occurred during follow-up in 216 patients who had achieved complete remission, providing a recurrence rate of 3.2% and recurrence death rate of 1.4%. All of the survivors were followed up for more than 5 years and 85.6% for more than 10 years. Toxicity of 5-fluorouracil was milder and less frequent than that of 6-mercaptopurine or methotrexate. The toxic reaction specific to 5-fluorouracil was diarrhea, which can result in pseudomembranous colitis if improperly treated. One of the two toxic deaths was due to this complication.

Roentgenologic manifestations of pulmonary metastases in choriocarcinoma and invasive mole.

From 1949 to 1975, a total of 3,915 chest films were taken for 429 cases of choriocarcinoma and 441 cases of invasive mole. The incidences of pulmonary metastases were 85.1% and 65.0%, respectively. The various forms of pulmonary metastases were studied and correlated with clinical symptoms and pathologic changes. In order to follow up the progression or regression of the various forms, serial chest films were taken at intervals of 10 to 14 days in 27 cases. In eight cases postmortem pulmonary arteriograms were obtained on the autopsied lung specimens for the study of vascular changes of metastatic lesions. Pathologic examinations and pulmonary arteriography were also done on the surgically resected lung specimens. As a result of this study, a relative comprehensive knowledge about the nature and development of the various forms of metastatic shadows has been deduced. It is rational to say that the various forms seen on the chest films represent only the various evolutionary changes of the same lesion.

Optimization of lipid composition in cationic emulsion as in vitro and in vivo transfection agents.

PURPOSE: To enhance in vitro and in vivo transfection activity by optimizing lipid composition of cationic lipid emulsions. METHODS: Various emulsion formulations having different cationic lipids as emulsifiers, and additional helper lipids as co-emulsifiers, were prepared. The stability of the emulsion and its complex with DNA was investigated by measuring the particle size change in phosphate buffer saline (PBS) over a period of 20 days. The activity of the emulsions in transfecting pCMV-beta into COS-1 cells in the presence or absence of 80% serum was evaluated. We also evaluated in vivo transfection activity using intravenously administered pCMV-Luc+ as a reporter gene. RESULTS: Among the cationic emulsifiers, 1,2-dioleoyl-sn-glycero-3-trimethylammonium-propane (DOTAP) formed the most stable and efficient emulsion gene carrier. Addition of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) increased in vitro transfection activity, but slightly compromised the stability of the emulsion. The loss was compensated for by including small amounts of Tween 80 in the emulsion. The in vitro and in vivo transfection activities were also increased by adding Tween 80. Even though in vitro transfection activity of liposomes was high in the absence of serum, the transfection activity of emulsions was far greater than that of liposomes in the presence of serum and for in vivo applications. CONCLUSIONS: By including DOPE as an endosomolytic agent and Tween 80 as a stabilization agent, the cationic emulsion becomes a more potent gene carrier for in vitro and in vivo applications, especially in the presence of serum.

A rapid assay method for ammonia using glutamine synthetase from glutamate-producing bacteria.

A rapid enzymatic assay method for ammonia was developed by using glutamine synthetase from glutamate-producing bacteria together with pyruvate kinase, lactate dehydrogenase, and NADH. The time required for determination of 25 nmol of ammonia was 5 min with 1 unit of glutamine synthetase, as opposed to 14-30 min with 1 unit of glutamate dehydrogenases from various sources. The present method was used to determine ammonia in serum, microbiol-culture broth, and waste water. The method can be modified for spectrophotometry in the visible region by substituting pyruvate oxidase, peroxidase, and appropriate chromogens for lactate dehydrogenase and NADH. With 4-aminoantipyrine (4AA) and phenol, and with 4AA and N-ethyl-N-2-hydroxyethyl-m-toluidine as chromogens, the sensitivity of ammonia determination was 0.65 and 1.7 times that with glutamate dehydrogenase, respectively. The present method was also applicable to the continuous detection of the activity of some ammonia-forming enzymes such as guanase, adenosine deaminase, and urease and to the determination of 0.5-30 microM ATP-ADP after some modification of the mixture.

Structure and mechanism of glutamate racemase from Aquifex pyrophilus.

Glutamate racemase (MurI) is responsible for the synthesis of D-glutamate, an essential building block of the peptidoglycan layer in bacterial cell walls. The crystal structure of glutamate racemase from Aquifex pyrophilus, determined at 2.3 A resolution, reveals that the enzyme forms a dimer and each monomer consists of two alpha/beta fold domains, a unique structure that has not been observed in other racemases or members of an enolase superfamily. A substrate analog, D-glutamine, binds to the deep pocket formed by conserved residues from two monomers. The structural and mutational analyses allow us to propose a mechanism of metal cofactor-independent glutamate racemase in which two cysteine residues are involved in catalysis.

Structural basis for cold adaptation. Sequence, biochemical properties, and crystal structure of malate dehydrogenase from a psychrophile Aquaspirillium arcticum.

Aquaspillium arcticum is a psychrophilic bacterium that was isolated from arctic sediment and grows optimally at 4 degrees C. We have cloned, purified, and characterized malate dehydrogenase from A. arcticum (Aa MDH). We also have determined the crystal structures of apo-Aa MDH, Aa MDH.NADH binary complex, and Aa MDH.NAD.oxaloacetate ternary complex at 1.9-, 2.1-, and 2.5-A resolutions, respectively. The Aa MDH sequence is most closely related to the sequence of a thermophilic MDH from Thermus flavus (Tf MDH), showing 61% sequence identity and over 90% sequence similarity. Stability studies show that Aa MDH has a half-life of 10 min at 55 degrees C, whereas Tf MDH is fully active at 90 degrees C for 1 h. Aa MDH shows 2-3-fold higher catalytic efficiency compared with a mesophilic or a thermophilic MDH at the temperature range 4-10 degrees C. Structural comparison of Aa MDH and Tf MDH suggests that the increased relative flexibility of active site residues, favorable surface charge distribution for substrate and cofactor, and the reduced intersubunit ion pair interactions may be the major factors for the efficient catalytic activity of Aa MDH at low temperatures.

Human cytomegalovirus gene products US3 and US6 down-regulate trophoblast class I MHC molecules.

The epidemiological correlation between human CMV (HCMV) infection and spontaneous fetal loss has been suggested, but the underlying mechanism is not well understood. Fetal cytotrophoblasts, which are in direct contact with the maternal immune system in the uterus during pregnancy, do not express HLA-A and HLA-B, but express the nonclassical class I HLA-G and HLA-C. It has been shown that both HLA-G and HLA-C are capable of inhibiting NK-mediated cell lysis. In our present study, using human trophoblast cell lines as well as other cell lines stably transfected with the human class I genes, we have demonstrated that HCMV US3 and US6 down-regulate the cell-surface expression of both HLA-G and HLA-C by two different mechanisms. HCMV US3 physically associates with both trophoblast class I MHC species, retaining them in the endoplasmic reticulum. In contrast, HCMV US6 inhibits peptide transport by TAP and thus specifically the intracellular trafficking of class I molecules. Therefore, these findings suggest for the first time a possible molecular mechanism underlying HCMV-related spontaneous pregnancy loss.

Cloning of a cDNA encoding bovine mitochondrial NADP(+)-specific isocitrate dehydrogenase and structural comparison with its isoenzymes from different species.

Mitochondrial NADP(+)-specific isocitrate dehydrogenase (IDP) was co-purified with the pyruvate dehydrogenase complex from bovine kidney mitochondria. The determination of its N-terminal 16-amino-acid sequence revealed that it is highly similar to the IDP from yeast. A cDNA clone (1.8 kb long) encoding this protein was isolated from a bovine kidney lambda gt11 cDNA library using a synthetic oligodeoxynucleotide. The deduced protein sequence of this cDNA clone rendered a precursor protein of 452 amino-acid residues (50,830 Da) and a mature protein of 413 amino-acid residues (46,519 Da). It is 100% identical to the internal tryptic peptide sequences of the autologous form from pig heart and 62% similar to that from yeast. However, it shares little similarity with the mitochondrial NAD(+)-specific isoenzyme from yeast. Structural analyses of the deduced proteins of IDP isoenzymes from different species indicated that similarity exists in certain regions, which may represent the common domains for the active sites or coenzyme-binding sites. In Northern-blot analysis, one species of mRNA (about 2.2 kb for both bovine and human) was hybridized with a 32P-labelled cDNA probe. Southern-blot analysis of genomic DNAs verified simple patterns of hybridization with this cDNA. These results strongly indicate that the mitochondrial IDP may be derived from a single gene family which does not appear to be closely related to that of the NAD(+)-specific isoenzyme.

A case-control study of trophoblastic diseases in the People's Republic of China.

A case-control study is currently under way in Beijing, People's Republic of China, involving approximately 165 patients with invasive moles or choriocarcinoma, 165 with hydatidiform moles, and 330 population controls, who were matched to the patients with invasive moles or choriocarcinoma on age and interval since last pregnancy. The interviews are focused on a number of suspected risk factors, including previous pregnancy outcomes, history of hydatidiform mole, medical factors, drug usage, family history, and diet. A brief background of the study and methods as established through a previous pilot study are given.

Structural and functional dissection of human cytomegalovirus US3 in binding major histocompatibility complex class I molecules.

The human cytomegalovirus US3, an endoplasmic reticulum (ER)-resident transmembrane glycoprotein, forms a complex with major histocompatibility complex (MHC) class I molecules and retains them in the ER, thereby preventing cytolysis by cytotoxic T lymphocytes. To identify which parts of US3 confine the protein to the ER and which parts are responsible for the association with MHC class I molecules, we constructed truncated mutant and chimeric forms in which US3 domains were exchanged with corresponding domains of CD4 and analyzed them for their intracellular localization and the ability to associate with MHC class I molecules. All of the truncated mutant and chimeric proteins containing the luminal domain of US3 were retained in the ER, while replacement of the US3 luminal domain with that of CD4 led to cell surface expression of the chimera. Thus, the luminal domain of US3 was sufficient for ER retention. Immunolocalization of the US3 glycoprotein after nocodazole treatment and the observation that the carbohydrate moiety of the US3 glycoprotein was not modified by Golgi enzymes indicated that the ER localization of US3 involved true retention, without recycling through the Golgi. Unlike the ER retention signal, the ability to associate with MHC class I molecules required the transmembrane domain in addition to the luminal domain of US3. Direct interaction between US3 and MHC class I molecules could be demonstrated after in vitro translation by coimmunoprecipitation. Together, the present data indicate that the properties that allow US3 to be localized in the ER and bind MHC class I molecules are located in different parts of the molecule.