[Effect of methylene blue labeling on therapeutic effect and prognosis of gastric cancer patients in D2 radical gastrectomy under laparoscope].

Objective: To investigate the effect of methylene blue tracing on the effect of surgical resection and the prognosis of gastric cancer patients in D2 radical surgery under laparoscope. Methods: In this retrospective cohort study, 160 patients with advanced gastric cancer who underwent surgical treatment in Xinxiang Central Hospital, the 4th Clinical College of Xinxiang Medical College from January 2016 to January 2019 were selected for retrospective analysis. Among them, 84 patients underwent laparoscopic D2 radical gastrectomy for gastric cancer combined with methylene blue labeling operation (labeling group), and the other 76 patients underwent only laparoscopic D2 radical gastrectomy for gastric cancer (control group). The difference of intraoperative and postoperative recovery, lymph node dissection, and postoperative 3-year cumulative survival rate between the two groups were analyzed. Results: The age of patients in the labeled group and the control group were (64.9±7.8) and (66.0±8.3) years old, respectively (P=0.389); And the male patients accounted for 61.9% (52 cases) and 55.3% (42 cases), respectively (P=0.394); The operation time in the labeled group was (218.5±19.6) min, which was shorter than that in the control group (230.1±17.4) min (P<0.001). There was no significant difference between the labeled group and the control group in the amount of bleeding during operation, the time of anal exhaust after operation, the time of eating after operation, the time of hospitalization after operation, and the average diameter of lymph nodes (P>0.05). The total number of dissected lymph nodes, D1 lymph nodes and D2 lymph nodes in the labeled group were significantly higher than those in the control group (all P values<0.05). The operative complication rate in the labeled group was 11.9% (10 cases), which was lower than that in the control group (25.0%, 19 cases) (P=0.032); There was no statistical significance in 3-year cumulative survival rates of patients between the labeled group (61.9%) and the control group (52.6%) (χ2=3.46,P=0.065). Conclusion: The use of methylene blue tracing in laparoscopic D2 radical surgery for gastric cancer is beneficial to reduce the operation time, improve the lymph node clearance rate, and reduce surgical complications.

Invasive fungal infection is associated with antibiotic exposure in preterm infants: a multi-centre prospective case-control study.

BACKGROUND: Previous antibiotic exposure is an important risk factor for invasive fungal infection (IFI). Antibiotic overexposure is common in lower-income countries; however, multi-centre studies concerning IFI in relation to antibiotic exposure are scarce. AIM: This prospective, multi-centre matched case-control study explored the correlation of IFI and antibiotic exposure in very preterm infants or very-low-birthweight infants admitted to 23 tertiary hospitals in China between 2018 and 2021. METHODS: Using a 1:2 matched design for gestational age, birth weight and early-onset sepsis (yes/no), the risk factors between infants diagnosed with IFI and infection-free controls were compared. The antibiotic use rate (AUR) was calculated using calendar days of antibiotic therapy in the 4 weeks preceding IFI onset divided by onset day of IFI. FINDINGS: In total, 6368 infants were included in the study, of which 90 (1.4%) were diagnosed with IFI. Median AUR, length of antibiotic therapy (LOT) and days of antibiotic therapy (DOT) within the 4 weeks preceding IFI onset were 0.90, 18 days and 30 days, respectively. Multi-variate analysis showed that a 10% increase in AUR, each additional day of DOT and LOT, and each additional day of third-generation cephalosporins and carbapenems were notably associated with IFI. CONCLUSION: Prolonged antibiotic therapy is common before the onset of IFI, and is an important risk factor, especially the use of third-generation cephalosporins and carbapenems. Antibiotic stewardship should be urgently developed and promoted for preterm infants in order to reduce IFI in lower-income countries such as China.

The emerging role of lncRNAs in the regulation of osteosarcoma stem cells.

OBJECTIVE: Osteosarcoma is a common bone sarcoma that often occurs in childhood and adolescence. In recent years, the efficacy of osteosarcoma treatments has been improved by adjuvant chemotherapies and surgical approaches. However, poor prognosis often occurs among osteosarcoma patients due to recurrence, metastasis, or drug resistance problems. Cancer stem cells (CSCs), a specific type of tumor malignant cells with stem cell-like properties, have been reported to be responsible for tumor origination, aggression, metastasis, recurrence, and drug resistance. CSCs have been identified in osteosarcomas treatment, which exhibits self-renewal, multi-potency, and enhanced drug resistance. Therefore, in the present narrative review, we intend to summarize the role of lncRNAs in regulating CSCs and their effectiveness in the treatment of osteosarcoma. MATERIALS AND METHODS: The databases PubMed (Medline), Web of Science, Embase, Scopus, and Cochrane Library, were used for the presented study. The keywords we used to complete our search are 'lncRNA', 'Stem cell', and 'osteosarcoma'. A total of over 800 relevant articles, with a time limit from 2010 to 2021, were identified according to search strategy. Duplicate records and review articles were excluded by their titles and abstracts. Finally, we found about 80 articles matching our inclusion criteria, which included about 13 relevant studies focusing on both the mechanism and effectiveness of osteosarcomas treatment among osteosarcoma patients. RESULTS: CD133, CD117, ALDH, and Stro-1 are validated as the stem cell biomarkers in osteosarcoma CSCs. Accumulating evidence has revealed that lncRNAs, containing HIF2PUT, SOX2-OT, MALAT1, THOR, B4GALT1-AS1, H19, PVT1, FER1L4, LINK-A, DANCR, and DLX6-AS1, play a potential role in regulating CSCs in osteosarcoma. The drug resistance, inhibition of the relapse, and metastasis in osteosarcoma could be avoided via regulating lncRNAs of targeting CSCs. CONCLUSIONS: Multiple lncRNAs regulate CSCs in osteosarcoma via various molecular mechanisms. This review demonstrated that the method of eliminating CSCs by targeting these lncRNAs is a safe, effective, and a well-tolerated way for osteosarcoma patients, which shows a broad research prospect in tumor diagnoses and therapies. However, this method should be further demonstrated by better animal models and more clinical experiments.

[Regulatory mechanism of interferon regulatory factor 1 by α-synuclein in mouse Parkinson's disease model].

OBJECTIVE: To investigate the molecular mechanism by which α-synuclein (α-Syn) regulates interferon regulatory factor 1 (IRF-1) expression. METHODS: SH-SY5Y cells overexpressing α-Syn and transgenic mouse model carrying human α-Syn gene with A53T mutation (3 and 6 months old) were examined for IRF-1 mRNA and protein expressions using real-time PCR and Western blotting, respectively. The subcellular localization of IRF-1 was determined with immunofluorescence staining and cytoplasmic/nuclear protein isolation. The optimal concentrations of the proteasome inhibitor MG132 (0.01-2.0 µmol/L) and lysosomal inhibitor chloroquine (5-200 µmol/L) for treatment of SH-SY5Y cells for 24 h were determined by examining the cell viability. SH-SY5Y cells were treated with 0.2 µmol/L MG132 and 30 µmol/L chloroquine for 24 h (the maximum dose that did not cause cell damage), and the changes of IRF-1 protein expressions was analyzed. The effects of α-Syn on MDM2 protein expression and IRF-1 ubiquitylation were analyzed using Western blotting and ubiquitylation assay. RESULTS: α-Syn overexpression did not affect the mRNA level of IRF-1 but significantly increased its protein level (P < 0.01). In α-Synoverexpressing SH-SY5Y cells, IRF-1 translocation was observed from the cytoplasm to the nucleus (P < 0.001). Treatment of the cells with 0.2 µmol/L MG132 significantly aggravated α-Syn-induced increase of IRF-1 protein expression (P < 0.01) while 30 µmol/L chloroquine produced no significant changes in IRF-1 level. α-Syn overexpression caused an obvious decrease of MDM2 protein level and further inhibited the ubiquitylation of IRF-1 (P < 0.01). CONCLUSION: α-Syn blocks MDM2-mediated ubiquitylation of IRF-1 through ubiquitin proteasome pathway, thereby enhancing IRF-1 protein expression.

[Molecular mechanism of miR-369-3p regulating hepatocellular carcinoma cell proliferation and apoptosis by targeting ACTN4].

Objective: To investigate the effect of miR-369-3p targeting ACTN4 expression on proliferation and apoptosis of hepatocellular carcinoma cells. Methods: Real-time quantitative polymerase chain reaction (RT-qPCR) and western blot were used to detect the expression levels of miR-369-3p and ACTN4 in hepatocarcinoma tissues and adjacent tissues. MiR-369-3p mimics, miR-negative control (NC), si-ACTN4, and si-NC were transfected into hepatocellular carcinoma MHCC97H cells by liposome method. Cell proliferation was detected by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-dipheny-ltetrazolium bromide (MTT) assay. Flow cytometry was used to detect cell cycle and apoptotic rates. The dual luciferase reporter assay was used to verify the targeted regulation of ACTN4 by miR-369-3p. Western blot was used to detect the expressions of cyclin D1, p21, Bcl-2 and Bax. Results: The expression level of miR-369-3p in liver cancer tissue was lower than that in adjacent tissues [(0.46±0.04) vs (1.00±0.08), P<0.001)], while the expression level of ACTN4 was higher than that in adjacent tissues [mRNA (3.12±0.29) vs (1.01±0.09); protein (0.61±0.06) vs (0.25±0.03), P<0.001]. Overexpression of miR-369-3p significantly decreased the cell viability[(0.71±0.06) vs (1.26±0.11), P<0.001)], increased cell apoptosis rate [(20.16±2.11)% vs (6.25±0.64)%, P<0.001], increased the proportion of cells in G(1) phase [(31.14±3.36)% vs (51.56±5.23)%, P<0.001], decreased the proportion of cells in S phase [(32.44±3.56)% vs (14.33) ±1.45)%, P<0.001], increased the levels of p21 and Bax protein (P<0.001), and decreased the levels of cyclin D1 and Bcl-2 protein (P<0.001). Inhibition of the expression of ACTN4 significantly reduced the cell viability [(0.78±0.07) vs (1.24±0.12), P<0.001], increased the apoptosis rate [(6.58±0.66)% vs (18.32±1.82)%, P<0.001], increased the proportion of cells in G(1) phase [(48.69±4.21)% vs (30.33±3.01)%, P<0.001], decreased the proportion of cells in S phase [(36.21±3.42)% vs (18.54±1.61)%, P<0.001], increased the protein levels of p21 and Bax (P<0.001), and decreased the levels of cyclin D1 and Bcl-2 protein (P<0.001). Compared with the miR-369-3p+ pcDNA group, overexpression of ACTN4 increased the proliferation ability of hepatocellular carcinoma MHCC97H cells at 72 hours of culture[(1.12±0.11) vs (0.68±0.06), P<0.001], significantly reduced the proportion of cells in G(1) stage [(38.81±3.24)% vs (51.80±4.57)%, P<0.001], significantly increased the proportion of S-phase cells [(31.65±3.11)% vs (15.69±1.44)%, P<0.001], decreased cell apoptosis rate [(13.86±1.37)% vs (22.69±2.24)%, P<0.001], increased protein expressions of cyclin D1 and Bcl-2 (P<0.001), decreased the protein expressions of p21 and Bax (P<0.001). Conclusion: MiR-369-3p can induce cell cycle arrest in G(1) phase, inhibit the proliferation and promote apoptosis of liver cancer cells by regulating the expression of ACTN4.

Clinical efficacy of mouse nerve growth factor plus nimodipine in neonatal intracranial hemorrhage and its effect on plasma PAF, CNP, MMP-2, and neurological function.

OBJECTIVE: To investigate the clinical efficacy of combination of mouse nerve growth factor (NGF) and nimodipine in the treatment of neonatal intracranial hemorrhage (NICH) and its effect on plasma platelet-activating factor (PAF), C-type natriuretic peptide (CNP), matrix metalloproteinase-2 (MMP-2), and neurological function. PATIENTS AND METHODS: A total of 90 infants with severe ICH admitted to our hospital from December 2016 to December 2018 were enrolled for retrospective study. According to different treatment schemes, they were assigned into 2 groups: group A (n=40) treated with mouse NGF plus nimodipine; group B (n=50) treated with nimodipine. The recovery time, serum indexes (PAF, MMP-2, CNP), neurological function (neonatal behavioral neurological assessment (NBNA) score), complications, and total effective rate of patients were recorded, and the satisfaction degree of family members was statistically analyzed. RESULTS: Patients in group A showed shorter recovery time, down-regulated PAF and MMP-2, evidently up-regulated CNP, and significantly increased NBNA score after one/two weeks of treatment, as well as fewer complications, higher total effective rate and higher satisfaction of family members. CONCLUSIONS: To sum up, the combination of mouse NGF and nimodipine achieves good clinical efficacy in NICH, which down-regulates plasma PAF and MMP-2, up-regulates CNP, and improves neurological function. Therefore, it is suitable for clinical promotion.

Correlations of MC4R and MSH2 expression with obesity in colon cancer patients.

OBJECTIVE: To investigate the correlations of MC4R and MSH2 with adult obesity, a total of 46 patients with early-stage colon cancer were treated in our hospital between February 2008 and February 2009 and were enrolled. PATIENTS AND METHODS: Venous blood was regularly drawn from subjects of the observation group and 48 healthy subjects for 6 years. Expression levels of MC4R and MSH2 genes were tested using quantitative polymerase chain reaction analyses, and the ensuing proteins were determined using enzyme-linked immunosorbent assays and Western blotting and immunohistochemical analyses. Finally, correlations with body mass index (BMI) and the presence of colon cancer were identified using multivariate analyses. RESULTS: Compared with the control group, MSH2 mRNA and protein expression increased significantly over time (p < 0.05) in patients with colon cancer. Moreover, MSH2 expression was correlated with colon cancer progression, and MC4R mRNA and protein expression increase concurrently in comparison with the control group (p < 0.05). Also, the mean BMI among patients with colon cancer was 30.8, whereas that among control subjects was only 21.4. These data indicate a relationship between BMI and colon cancer. CONCLUSIONS: Expression of MSH2 in patients with colon cancer may promote the expression of the obesity gene MC4R, potentially contributing to body weight gains.

Silencing of ATPase family AAA domain-containing protein 2 inhibits migration and invasion of colorectal cancer cells.

Colorectal cancer is one of the most common malignant tumors with a high rate of distant metastasis, postoperative recurrence and mortality. ATPase family AAA domain-containing protein 2 (ATAD2), a member of ATPase family, is highly expressed in various cancers, including colorectal cancer. However, whether ATAD2 plays a role in the migration and invasion of colorectal cancer cells remains unknown. In this study, we established ATAD2 knockdown in colorectal cancer cell lines by RNA interference and found that silencing of ATAD2 inhibited the migration and invasion ability of Caco-2 and SW-480 cells. Moreover, ATAD2 silencing suppressed epithelial-mesenchymal transition (EMT), and reduced the expression and enzymatic activity of matrix metalloproteinases (MMPs) in Caco-2 and SW-480 cells. In summary, our results suggest that silencing of ATAD2 inhibits migration and invasion of colorectal cancer cells by suppressing EMT and decreasing the activity of MMPs. Hence, ATAD2 could be considered as a novel molecular marker of metastatic colorectal cancer, and it may provide new insights for clinical diagnosis and treatment of colorectal cancer.

MicroRNA-520f suppresses growth of gastric carcinoma cells by target ATPase family AAA domain-containing protein 2 (ATAD2).

MicroRNAs (miRNAs) are small, non-coding RNAs that can serve as tumor suppressor genes or oncogenes in tumorigenesis. More and more evidence demonstrate that abnormal expression of miRNAs lead to the gastric carcinoma occurrence. In the present study, we revealed that the expression levels of miR-520f were significantly down-regulated in gastric carcinoma cells and clinical gastric carcinoma samples. Next, we demonstrated that introduction of miR-520f inhibited the growth of gastric carcinoma cells in vitro. However, down-regulate the expression levels of miR-520f by anti-miR-520f lead to an enhanced cell proliferation, implying that miR-520f maybe serve as a novel tumor suppressor. Moreover, we found that ATPase family AAA domain-containing protein 2 (ATAD2) was one target genes of miR-520f downstream regulator, which caused the decreased expression of ATAD2. Meanwhile, the overexpression of ATAD2 reversed the inhibited proliferation ability caused by miR-520f. Therefore, our find that miR-520f involves in gastric carcinoma proliferation, pointing a therapeutic probability of miR-520f in the therapy of gastric carcinoma.

Id1 knockdown induces the apoptosis and inhibits the proliferation and invasion of ovarian cancer cells.

OBJECTIVE: To explore the role of Id1 in ovarian cancer cell proliferation, invasion and apoptosis. MATERIALS AND METHODS: Lentivirus-based shRNA vectors were constructed to knockdown Id1 expression in SKOV3 ovarian cancer cells. The proliferation, invasion ability and apoptosis of SKOV3 cells were evaluated by CCK-8 assay, transwell assay and flow cytometry, respectively. RESULTS: Compared to control cells, cell proliferation and invasion were significantly inhibited in SKOV3 cells depleted of Id1, while apoptosis was significantly increased in SKOV3 cells depleted of Id1. CONCLUSIONS: Id1 functions to promote ovarian cancer cell proliferation and invasion, and Id1 is a promising therapeutic target for ovarian cancer.

Study on the expression of VEGF and HIF-1α in infarct area of rats with AMI.

OBJECTIVE: To investigate the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1α (HIF-1α) in infarct area of rats with acute myocardial infarction (AMI). MATERIALS AND METHODS: A total of 36 healthy male Wistar rats weighing 180 g-220 g were included in our study and were randomly divided into two groups of 6 rats each: sham operation group and experiment group. In sham operation group, surgery was performed by opening chest without ligation of arteria coronaria while, in the experiment group, surgery was performed to produce AMI model. Animals were sacrificed immediately after the operation on day 7 and day 14, respectively. The serum troponin, myocardial infarct area, microvessel density in infarct area, VEGF and HIF-1α expression were analyzed. RESULTS: Differences in the serum troponin level, myocardial infarct area, microvessel density in infarct area, VEGF and HIF-1 expression level at different time points in sham and experiment groups had statistical significance (p < 0.05). On day 7, the serum troponin, myocardial infarct area, microvessel density in infarct area, VEGF and HIF-1 expression level were the highest and the level was second highest on day 14 while the levels were lowest immediately after the operation. The expression levels of VEGF and HIF-1α were positively related with the increasing density of microvessel in infarct area (p < 0.05). CONCLUSIONS: The expression of VEGF and HIF-1α might be involved with myocardial remodeling and angiogenesis.

Effect of atorvastatin on diabetic rat endothelial cells and retinal lesions.

We investigated the effect of atorvastatin on vascular endothelial growth inhibitor (VEGI) expression in rats with diabetic retinopathy. Wistar rats were divided into a blank group and diabetic model group, which was further randomly divided into treatment and control groups. Rats in the treatment group received 10 mg/kg atorvastatin daily, while rats in the blank and control groups received normal saline. Rats were randomly euthanized at 3 or 6 months. Immunohistochemical staining was used to determine changes in VEGI and vascular endothelial growth factor, interleukin-4, and tumor necrosis factor α levels in rats with diabetic retinopathy. Survival rate in the treatment group was 84% (63/75) after 6 months, which was significantly higher than that in the control group (P < 0.05); rats in the control group showed the lowest survival rate. Survival in the treatment group was higher than that in the control group but not significant compared with the blank group after 3 months. VEGI, vascular endothelial growth factor, tumor necrosis factor α, and interluekin-4 expression was lower than that in the control group, but higher than the blank group after 3 months. The expression of each factor decreased to the blank group level in the treatment group and was significantly lower than that in the control group after 6 months (P < 0.05). Expression in control and blank groups was similar at 3 and 6 months. Atorvastatin can inhibit VEGI and vascular endothelial growth factor expression to protect rats from diabetic retinopathy.

Defective expression of regulatory B cells in iodine-induced autoimmune thyroiditis in non-obese diabetic H-2(h4) mice.

INTRODUCTION: The ability of B cells to negatively regulate cellular immune responses and inflammation has been described. The regulatory B (Breg) cells with the unique CD1d(hi)CD5(+)CD19(+) phenotype and the capacity to produce IL-10 are potent negative regulators of inflammation and autoimmunity in several in vivo mouse models of autoimmune disease. AIM: To investigate whether Breg cell deficiency participates in autoimmune thyroiditis (AIT) in an animal model. MATERIALS AND METHODS: Non-obese diabetic (NOD).H-2(h4) mice at 4 weeks of age were randomly divided into control and iodine-treated groups; the iodine-treated group received sterile water containing 0.005 % NaI for 10 or 20 weeks. The percentage of CD1d(hi)CD5(+)CD19(+) Bregs, CD4(+)CD25(+)FoxP3(+) regulatory T cells (Treg) and CD4(+)IL17(+) T helper 17 cells (Th17) in splenic mononuclear cells was detected by multicolor flow cytometry. The expression of IL-10 mRNA and TGF-ß mRNA in splenocytes was measured by real-time RT-PCR. RESULTS: NOD.H-2(h4) mice spontaneously develop anti-thyroglobulin autoantibodies and intrathyroidal lymphocyte infiltration when supplied with iodine in drinking water. Mice with AIT had a decreased CD1d(hi)CD5(+)CD19(+) Breg subset and reduced IL-10 mRNA expression in splenocytes compared with controls (p < 0.05) and maintained relatively low levels during the development of thyroiditis. The proportion of Breg cells was negatively correlated with the proportion of Th17 cells, but positively correlated with CD4(+)CD25(+)FoxP3(+) Treg cells in splenocytes (All p < 0.05). CONCLUSIONS: The defective expression of Breg cells combined with impaired Treg cells and enhanced Th17 cells might play an important role in the development of iodine-induced AIT in NOD.H-2(h4) mice.

Treatment of strong domestic sewage in a 96 m3 UASB reactor operated at ambient temperatures: two-stage versus single-stage reactor.

A 96 m3 UASB reactor was operated for 2.5 years under different conditions to assess the feasibility of treating strong sewage (COD(tot) = 1531 mg/l) at ambient temperatures with averages of 18 and 25 degrees C for winter and summer respectively. During the first year, the reactor was operated as a two-stage system at OLRs in the range of 3.6-5.0 kg COD/m3 d for the first stage and 2.9-4.6 kg COD/m3 d for the second stage. The results of the first stage showed average removals of 51% and 60% for COD(tot) and COD(ss) respectively without significant effect of temperature. The second stage reactor was unstable. The temperature affected sludge stabilization. During the second year, the first stage was operated as a single-stage UASB reactor at half of the previous loading rates. The results showed an average removal efficiency of 62% for COD(tot) during summer, while it dropped to 51% during wintertime. However, the effluent suspended solids were stabilized with VSS/TSS ratio around 0.50 all over the year. The sludge in the single-stage reactor was well-stabilized and exerted an excellent settlability. During the last three months of research, sludge was discharged regularly from the single-stage UASB reactor. The results showed no significant improvement in the performance in terms of COD(tot). Based on the results of the experiment, a single-stage UASB reactor operated at relatively long HRT is preferred above two-stage system at the Jordanian conditions.

Heterogeneous processing and zona pellucida binding activity of pig zonadhesin.

Zonadhesin is a mosaic protein in sperm membrane fractions that binds directly and in a species-specific manner to the extracellular matrix (zona pellucida) of the oocyte. The active form of pig zonadhesin from capacitated, epididymal spermatozoa comprises two covalently associated polypeptide chains of M(r) 105,000 (p105) and M(r) 45,000 (p45). Here we report detection and characterization of multiple zonadhesin isoforms in freshly ejaculated cells. Antibodies to the predicted von Willebrand D0-D1, D1, and D3 domains of pig zonadhesin recognized p105, p45, and additional M(r) 60,000-90,000 polypeptides in particulate fractions of uncapacitated cells. Although the p105/45 form constituted a minority of all zonadhesin forms in sperm membrane fractions, it was the predominant form capable of binding to the pig zona pellucida. Zonadhesin-binding sites were distributed over the entire zona pellucida. Anion exchange chromatography resolved active, p105/45 zonadhesin from the p60-90 inactive forms. Without disulfide bond reduction some zonadhesin was M(r) > or = 300,000, including M(r) 300,000 and 900,000 proteins comprising in part multimers of p105/45. The multimeric forms did not bind the zona pellucida as avidly as did the p105/45 monomer. Expressed D1 and D3 domain fragments containing the CG(L/V)CG sequence motif spontaneously formed multimers at -246 mV E(h) in vitro. Double Cys --> Ser mutants of the D1 fragment formed multimers with the same apparent kinetics as the wild type protein. Zonadhesin localized to the apical head of pig spermatozoa. We conclude that a heterogeneous combination of specific proteolysis and intermolecular disulfide bond formation in the sperm head generates multiple forms of zonadhesin with differing avidities for the zona pellucida.

Stability of luteinizing hormone releasing hormone: effects of pH, temperature, pig skin, and enzyme inhibitors.

The purpose of this investigation was to determine the stability of luteinizing hormone releasing hormone (LHRH) as a function of solution pH, temperature, and pig skin with and without enzyme inhibitors. LHRH, incubated with a 0.1 M phosphate buffer (pH 2.5-8.1), pig skin, and pig skin with enzyme inhibitors, was analyzed using reversed-phase high performance liquid chromatography. The solution's pH affected the rate constants of LHRH, following apparent first-order kinetics. Maximum stability was achieved at pH 6.05. Therefore, the effect of various temperatures (i.e., 65, 75, 80, and 90 degrees C) was studied on the stability of LHRH at pH 6.05. The activation energy for the overall reaction was 23.4 kcal/mol at pH 6.05. The shelf-life of LHRH at 25 degrees C and pH 6.05, calculated using the Arrhenius equation, was approximately 4 years. The rate constant of LHRH in the skin (area: 9 cm2; thickness: 0.5 mm) was 0.167 hr-1. Out of three inhibitors (i.e., aprotinin, bestatin, and leupeptin), bestatin had the best stabilizing effect on the degradation of LHRH by the skin. The rate constant of LHRH in the presence of bestatin was 0.082 hr-1. Sixty percent of LHRH was found to be degraded in the skin within 5 hr in the absence of enzyme inhibitors, whereas only 33% of LHRH was degraded in the presence of bestatin (an aminopeptidase inhibitor).

Application of solid-phase microextraction to the recovery of explosives and ignitable liquid residues from forensic specimens.

A current review of the application of solid-phase microextraction (SPME) to the analysis of ignitable liquids and explosive residues is presented along with experimental results demonstrating the relative effects of controllable variables. Variables discussed include fiber chemistry, adsorption and desorption temperatures, extraction and desorption times, fiber sampling placement (direct, headspace, and partial headspace) and matrix effects, including water content. SPME is shown to be an inexpensive, rapid and sensitive method for the analysis of ignitable liquids and high explosives residues from solid debris samples and from aqueous samples. Explosives are readily detected at parts per trillion concentrations and ignitable liquids are reproducibly detected at levels below those using conventional methods.

Effect of buffer pH, buffer concentration and skin with or without enzyme inhibitors on the stability of [Arg(8)]-vasopressin.

The stability of [Arg(8)]-vasopressin (AVP) as a function of buffer pH, buffer concentration, salt concentration, temperature, and skin with and without enzyme inhibitors was investigated. AVP was analyzed by reverse-phase high-performance liquid chromatography. The results indicated that the buffer's pH affected the degradation rate of AVP. Buffer ions (H(2)PO(4)(-) and HPO(4)(2-)) and salt concentrations had no effect on the degradation of AVP. Maximum stability was achieved at pH 3.35 among pH values tested. The activation energy for the overall reaction was 21.5 kcal mol(-1) at pH 3.35. From the Arrhenius equation, the shelf-life of AVP at 25 degrees C and pH 3.35 was calculated to be 1.38 years. The degradation rate of AVP in the skin (area: 9 cm(2), thickness: 0.5 mm) was 0.22 h(-1). Bestatin (an aminopeptidase inhibitor) had the best stabilizing effect on the degradation of AVP by skin among the three enzyme inhibitors (i.e. aprotinin, bestatin, and leupeptin) studied. The degradation rate of AVP in the skin was reduced to 0. 059 h(-1) in the presence of bestatin in comparison with no inhibitor (0.22 h(-1)).

[Determination of trace arsenic using GFAAS with metal-coated graphite tube].

The sensitivity, precision and disturbance-resisting property were studied by using metal-coated graphite tube for electrically heated atomic absorption spectrometry. The surface characteristic of the metal-coated graphite tube was studied by using X-ray diffraction meter and scanning electron microscope. The mechanism of satisfactory performance was discussed.