[Research and exploration of salivary biological markers for hepatitis B-related hepatocellular carcinoma]

Objective: To study using isotope-labeled relative and absolute quantitative proteomics methodologies to screen for salivary biological markers as a simple, non-invasive tool for identifying hepatitis B-related HCC at an early stage. Methods: Saliva samples were collected to extract salivary proteins. Isotope-labeled relative and absolute quantitative proteomics were used to analyze the differentially expressed proteins between the hepatocellular carcinoma (HCC) and non-HCC groups. Western blotting, immunohistochemistry, and enzyme-linked immunosorbent assays were used to verify differential proteins and identify markers in liver cancer tissues and saliva. Statistical analysis was used to analyze the diagnostic efficiency of salivary biomarkers. Results: 152 differentially expressed salivary proteins were screened out between the HCC and non-HCC groups. Western blot, immunohistochemistry, and enzyme-linked immunosorbent assays validated that the expressions of α-1-acid glycoprotein 1 (ORM1) and alpha-fetoprotein (AFP) were significantly increased in HCC (P < 0.05). There was a significant correlation between salivary AFP and serum AFP (P < 0.05). HCC was diagnosed when salivary α-1-acid glycoprotein 1 combined with AFP. The area under the receiver operating characteristic curve was 0.8726 (95% confidence interval: 0.8104 ~ 0.9347), the sensitivity was 78.3%, and the specificity was 88%. Conclusion: Salivary AFP and α-1-acid glycoprotein 1 can serve as potential biomarkers for hepatitis B-related hepatocellular carcinoma.

[Epidemiological investigation on the local epidemic situation in Zhengzhou High-Tech Zone caused by SARS-CoV-2 Delta variant]

This study collected epidemic data of COVID-19 in Zhengzhou from January 1 to January 20 in 2022. The epidemiological characteristics of the local epidemic in Zhengzhou High-tech Zone caused by the SARS-CoV-2 Delta variant were analyzed through epidemiological survey and big data analysis, which could provide a scientific basis for the prevention and control of the Delta variant. In detail, a total of 276 close contacts and 599 secondary close contacts were found in this study. The attack rate of close contacts and secondary close contacts was 5.43% (15/276) and 0.17% (1/599), respectively. There were 10 confirmed cases associated with the chain of transmission. Among them, the attack rates in close contacts of the first, second, third, fourth and fifth generation cases were 20.00% (5/25), 17.86% (5/28), 0.72% (1/139) and 14.81% (4/27), 0 (0/57), respectively. The attack rates in close contacts after sharing rooms/beds, having meals, having neighbor contacts, sharing vehicles with the patients, having same space contacts, and having work contacts were 26.67%, 9.10%, 8.33%, 4.55%, 1.43%, and 0 respectively. Collectively, the local epidemic situation in Zhengzhou High-tech Zone has an obvious family cluster. Prevention and control work should focus on decreasing family clusters of cases and community transmission.

[Application of pretrained model based on electronic medical record in recognition of acute respiratory infection]

Objective: To evaluate the recognition of acute respiratory infection (ARI) by a pretrained model based on electronic medical records (EMRs). Methods: 38 581 EMRs were obtained from Chongqing University Three Gorges Hospital in December 2021. Bidirectional encoder representation from transformers (BERT) pretrained model was used to identify ARI in EMRs. The results of medical professionals were considered as the gold standard to calculate the sensitivity, specificity, Kappa value, and area under the curve of the receiver operating characteristic (AUC). Results: There were 3 817 EMRs in the test set, with 1 200 ARIs. A total of 1 205 cases were determined as ARI by the model, with a sensitivity of 92.67% (1 112/1 200) and a specificity of 96.45% (2 524/2 617). The model identified ARI with similar accuracy in males and females (AUCs 0.95 and 0.94, respectively), and was more accurate in identifying ARI cases in those aged less than 18 than in adults 18-59 and adults 60 and older (AUCs 0.94, 0.89 and 0.94, respectively). The current model had a better identification of ARIs in outpatient patients than that in hospitalized patients, with AUCs of 0.74 and 0.95, respectively. Conclusion: The use of the BERT pretrained model based on EMRs has a good performance in the recognition of ARI cases, especially for the outpatients and juveniles. It shows a great potential to be applied to the monitoring of ARI cases in medical institutions.

Computer-aided three-dimensional assessment of periodontal healing distal to the mandibular second molar after coronectomy of the mandibular third molar: a prospective study

Background

The periodontal healing distal to the mandibular second molar (M2M) after coronectomy of the M3M has shown controversial results. We aimed to combine a digital method with cone-beam computed tomography (CBCT) and estimate periodontal healing of M2M after M3M coronectomy. An accurate and stable indicator in three dimensions was also explored tentatively.

Methods

Patients with a M3M in contact with the inferior alveolar canal were included. CBCT was applied immediately after coronectomy (baseline) and 6-months later. Data were investigated with digital software for registration. Previously reported and coronectomy-related factors were included for univariate and multivariate analyses.

Results

A total of 181 patients (213 M3Ms) completed 6-month follow-up. Significant reduction in the distal intra-bony defect (DBD) depth of the M2M was shown (1.28 ± 1.24 mm, P < 0.001). DBD depth of the M2M at baseline was the most influential factor (r = 0.59), followed by preoperative M3M condition, age, rotation and migration of the root complex. Remaining enamel (OR = 6.93) and small retromolar space (0.67) contributed to re-contact of the root complex and M2M. Bone volume regenerated in the distal 2 mm was associated significantly with DBD-depth reduction (r = 0.74, P < 0.001).

Conclusions

Bone volume regenerated in the distal 2 mm of the M2M denoted stability of distal periodontal healing of the M2M. DBD depth at baseline was the most influential factor for healing of a DBD of the M2M after M3M coronectomy. The remaining enamel and a small retromolar space could contribute to re-contact of the root complex and the M2M.

Trial registration

China Clinical Trial Center, ChiCTR1800014862. Registered 10 February 2018,

High-throughput sequencing analysis of marine pioneer surface-biofilm bacteria communities on different PDMS-based coatings

Marine biofilms, the attachment of marine microorganisms on artificial surfaces in natural seawater, play critical roles in the development of marine biofouling, which pave ways for the settlement and colonization of sessile invertebrate larvae. Despite the excellent microbe-inhibitory effect of polydimethylsiloxane (PDMS)-based coatings, marine bacteria could still attach to surfaces and form natural biofilms. However, there is little information available on the common structural features of pioneer surface-biofilm bacteria (PSB) communities on different PDMS-based coatings with regard to their compositions, distributions and diversity. Herein, the present study aims to explore the compositional and structural features of the PSB communities on different PDMS-based coatings using 16S rRNA gene amplicon sequencing in terms of the taxonomic structures at phylum, family and genus level. The results revealed the PSB communities on different PDMS-based coatings possessed high similarities in compositional, structural and diversity features, but varied greatly in relative abundance and distributions. Proteobacteria was the most diverse and overwhelming phylum in biofilms formed on all PDMS-based coatings, followed by Cyanobacteria. In addition, the decreased abundance of Proteobacteria and the increased abundance of Cyanobacteria on the carbon nanotubes (CNTs)-modifed PDMS composites (CPCs) may contribute to their differential anti-biofouling effect against the colonization of juvenile macrofoulers.

CdSe quantum dots labeled Staphylococcus aureus for research studies of THP-1 derived macrophage phagocytic behavior

A simple biological strategy to couple intracellular irrelated biochemical reactions of staphylococcus aureus CMCC 26003 (S. aureus) with inorganic metal ions to synthesize cadmium selenide quantum dots (CdSe QDs) was demonstrated. Correspondingly, S. aureus as living matrices are internally generated and labeled with fluorescent QDs by the smart strategy. Several key factors in the process of biosynthesis were systematically evaluated. At the same time, ultraviolet-visible (UV-Vis), photo-luminescence (PL), inverted fluorescence microscopy and transmission electron microscopy (TEM) were utilized to study the characters of the as produced CdSe QDs. In addition, cytotoxicity and photostability of the QDs containing bacteria were also tested and evaluated as a whole. The results showed that intracellular CdSe nanocrystals had successfully formed in S. aureus living cells, which were less toxic, highly fluorescent and photostable. These fluorescent S. aureus bacteria were next applied as invading pathogens as well as fluorescent bioprobes for exploring the phagocytic behavior of THP-1-derived macrophage. Results proved that internal CdSe QDs labeling had no significantly adverse effects compared with the kind of infection reference, fluorescein isothiocyanate (FITC) stained S. aureus pathogen. Assuredly, the methods presented here provide researchers with a useful option to analyze the behavior of S. aureus as a type of infectious pathogen, which would also help understand the complex interplay between host cells and the invading bacteria on molecular level.

[Experimental study on the effects of tumor necrosis factor-α monoclonal antibody on autophagy level in allergic rhinitis mice]

Objective: To observe the effect of tumor necrosis factor-α (TNF-α) monoclonal antibody on autophagy in allergic rhinitis (AR) mice. Methods: Thirty six weeks old BALB/c mice were randomly divided by random number table method into five groups: control group, model group (AR group), TNF-α antibody intervention group (AR+TNF-α group), autophagy inhibitor (3-methylindole, 3-NA) intervention group (AR+3-MA group), TNF-α antibody combined with autophagy inducer rapamycin (RAP) intervention group (AR+TNF-α+RAP group), with 6 mice in each group. AR model was established by conventional method, the corresponding reagent was administered before nasal cavity stimulation sensitization and during the whole experiment. Behavioral scores of mice were obtained, blood was collected from the eye socket, and mice in each group were sacrificed to collect nasal mucosa tissue samples. Pathological changes of nasal mucosa were observed by hematoxylin-eosin staining. Expression levels of inflammatory factor and IgE in serum were detected by enzyme-linked immunosorbent assay (ELISA). Expressions of autophagy related indicators microtubule-associated protein-1 light chain-3B (LC3B), Beclin-1, sequestosome1 (p62), autophagy-related 5 (ATG5), autophagy-related 7 (ATG7) were measured by Real-time PCR and Western blot. The aggregation of LC3B protein was observed by immunofluorescence. SPSS 19.0 software was used for statistical analysis. Results: Compared with the AR model group, symptoms of AR in AR+TNF-α group and AR+3-MA group were mild; the pathological changes of nasal mucosa were weak; the expression of IgE, TNF-α, interleukin 4 (IL-4), interferon-γ (IFN-γ) in serum significantly reduced (IgE: 666.19±78.35 (x±s) vs. 692.38±64.29 vs. 1 059.05±146.44, TNF-α: 112.06±12.95 vs. 113.17±15.43 vs. 161.22±17.96, IL-4: 54.05±7.14 vs. 58.26±5.67 vs. 79.95±6.33, IFN-γ: 28.58±4.51 vs. 30.67±2.60 vs. 39.83±3.31, all P<0.05), and the expression of LC3B Ⅱ/Ⅰ, Beclin-1, ATG5, ATG7 in nasal mucosa significantly decreased, the expression of p62 significantly elevated. After intervention with autophagy inducer RAP, the therapeutic effect of TNF-α monoclonal antibodies on AR was antagonized. Conclusion: TNF-α monoclonal antibody significantly improves nasal symptoms in AR mice by inhibiting autophagy levels.

[Timeless promotes the proliferation of hepatocellular carcinoma cell by reprogramming of glucose metabolism]

Objective: To explore the function and molecular mechanism of Timeless in promoting hepatocellular carcinoma (HCC) growth. Methods: The expression of Timeless in HCC and paracancer tissues were analyzed by using the public data of HCC. Timeless was overexpressed in MHCC97L cells and silenced in MHCC97H cells, respectively, and the expression of Timeless and its downstream molecules were detected by real-time PCR and western blot. The effects of Timeless on cell glycolysis, oxidative phosphorylation and proliferation were detected by the glucose uptake experiment, lactic acid detection experiment, the extracellular fluid pH detection experiment, cell oxygen consumption test and cell viability assay, respectively. Results: The level of Timeless in HCC tissue was significantly higher than that of paracancer tissue (P<0.05). The relative cellular glucose uptake levels in the groups of Timeless knockdown, including siTimeless-1 and siTimeless-2 group were 0.510±0.119 and 0.508±0.099, respectively, significantly different from that of control group (P<0.05); The relative cellular uptake level of Timeless overexpressed group was 1.953±0.324, significantly different from that of vector transfected group (P<0.05). The relative levels of lactic acid production in the siTimeless-1 and siTimeless-2 group were 0.579±0.096 and 0.550±0.120, respectively, significantly different from that of control group (P<0.05); The relative production level of lactic acid in the Timeless overexpressed group was 1.463±0.179, significantly different that of vector transfected group (P<0.05). The extracellular pH values of siTimeless-1 and siTimeless-2 group were 7.390±0.035 and 7.370±0.060, respectively, significantly different from that of control group (P<0.05); the extracellular pH value of Timeless overexpressed group was 7.130±0.031, significantly different than vector transfected group (P<0.05). Oxygen consumption rate of siTimeless-1 and siTimeless-2 group were 3.686±0.389 and 3.955±0.431, respectively, significantly higher than 1.690±0.297 of control group (P<0.05); Oxygen consumption rate of Timeless overexpressed group was 1.302±0.336, significantly lower than 3.185±0.262 of vector transfected group (P<0.05) Timeless inhibited the expression of p53. The cell glucose uptake, lactic acid production, the pH of extracellular culture medium and cell oxygen consumption of control group were not significantly different from that of Timeless and p53 co-silenced group [(si-Timeless+sip53) group] (P>0.05); the glucose uptake, the production of lactic acid, the pH of the extracellular culture medium and the oxygen consumption of Timeless co-transfected with p53 (Timeless+p53) group were not significantly different from those of vector transfected group (P>0.05). Timeless promoted the proliferation of HCC cells through inhibiting the expression of p53. Conclusion: Timeless promotes reprogramming of glucose metabolism and proliferation of HCC cells by inhibiting the p53-dependent signaling pathway.

[LincRNA-ROR functions as a ceRNA to regulate Oct4, Sox2, and Nanog expression by sponging miR-145 and its effect on biologic characteristics of colonic cancer stem cells]

Objective: To investigate the impact of lincRNA-ROR, a ceRNA by binding miR-145 on the expression of the downstream genes Oct4, Sox2 and Nanog, and related biological characteristics of colon cancer stem cells, and to elucidate the clinical significance of this molecular regulatory network. Methods: Fifty-two cases of colorectal cancer tissue and adjacent tissue were collected at Nanyang City Central Hospital and Nanyang Second Hospital, Henan Province, from 2014 to 2016. Real-time quantitative polymerase chain reaction (qPCR) was used to detect the expression of lincRNA-ROR and miR-145 in colorectal cancer tissue and isolated colon cancer cells. The correlation between the expression of lincRNA-ROR, miR-145 and the clinicopathologic features of colon cancer was performed. CD44(-)CD133(-) and CD44(+) CD133(+) cells were isolated from SW1116 by using flow cytometry. The expression of CD44, CD133, Oct4, Sox2, Nanog, lincRNA-ROR and miR-145 in cells were detected by qPCR. The relationship between lincRNA-ROR, miR-145, Oct4, Sox2 and Nanog was analyzed by bioinformatics, dual luciferase reporter assay, qPCR and Western blot. The effects of silencing lincRNA-ROR on the proliferation and chemosensitivity of colon cancer stem cells were detected by MTT, colony formation. Results: LincRNA-ROR was frequently up-regulated and inversely correlated with miR-145 down-regulation in the colon cancer specimens(P<0.05). LincRNA-ROR was related to tumor size, lymph node involvement and distant metastasis(P<0.05), and miR-145 was found related to tumor size and tumor location(P<0.05). CD44(+) CD133(+) cells were successfully isolated from SW1116 by flow cytometry. The levels of CD44, CD133, Oct4, Sox2, Nanog, lincRNA-ROR in CD44(+) CD133(+) cells were significantly increased, while miR-145 was decreased compared with CD44(-)CD133(-)cells(P<0.05). The levels of CD44, CD133, lnc-ROR in CD44(+) CD133(+) cells were significantly reduced upon cell adherence, while miR-145 was significantly increased(P<0.05). Bioinformatics analysis revealed that lincRNA-ROR shared miRNA response elements with core transcription factors Oct4, Sox2 and Nanog. MiR-145 significantly inhibited the expression of lincRNA-ROR, Oct4, Sox2 and Nanog. Silencing lincRNA-ROR significantly inhibited colon cancer stem cells proliferation and increased the sensitivity to chemotherapy. Conclusions: Linc-ROR functions as a key ceRNA to prevent core TFs, e. g., Oct4, Sox2, Nanog, from miR-145-mediated suppression in colon cancer stem cells and regulates cell proliferation and chemosensitivity.The data may provide insights into the pathophysiological interactions of the components of genetic networks in the development of colon cancer and may lead to new therapies in the future.

Methylmercury-l-Cysteine targeting L-type amino acid transporter conjugate cytotoxicity on C6 glioma cells

Glioma is the most common primary tumor in the brain, accounting for about 40~50% of intracranial primary tumors. Most chemotherapeutic drugs have difficulty in penetrating the blood-brain barrier, and their clinical applications are greatly limited. We evaluated the effects of methylmercury-L-cysteine (MeHg-L-cys) and methylmercury chloride (MMC) on apoptosis of C6 glioma cells. L-type amino acid transporter (LAT1) was used to investigate the targeted transport function and cytotoxicity of MeHg- L-cys in glioma. MeHg-L-cys enhanced the ability of targeting glioma cells and reduced the adverse reactions to normal brain tissues. Therefore, it is significantly important to develop new anti-glioma drugs targeting the blood-brain barrier.

Fluorescent CdSe QDs containing Bacillus licheniformis bioprobes for Copper (II) detection in water

Quantum dots (QDs) are semiconductor nanoparticles (NPs) that offer valuable functionality for cellular labeling, drug delivery, solar cells and quantum computation. In this study, we reported that CdSe QDs could be bio-synthesized in Bacillus licheniformis. After optimization, the obtained CdSe QDs exhibited a uniform particle size of 3.71±0.04nm with a maximum fluorescence emission wavelength at 550nm and the synthetical positive ratio can reach up to 87%. Spectral properties, constitution, particle sizes and crystalline phases of the CdSe QDs were systematically and integrally investigated. The CdSe QD-containing Bacillus licheniformis cells were further used as whole fluorescent bio-probes to detect copper (II) (Cu²⁺) in water, which demonstrated a low limit of detection (0.91μM). The assay also showed a good selectivity for Cu²⁺ over other ions including Al³⁺, Cd²⁺, Mg²⁺, K⁺, Na⁺, NH₄⁺, Zn²⁺, CH₃COO⁺, Pb²⁺ and I^-. Our study suggests the fluorescent CdSe QDs-containing Bacillus licheniformis bio-probes as a promising approach for detection of Cu²⁺ in complex solution environment.

Occurrence, distribution and risk assessment of suspected endocrine-disrupting chemicals in surface water and suspended particulate matter of Yangtze River (Nanjing section)

The occurrence and distribution of eight selected endocrine-disrupting chemicals were investigated in samples of surface water and suspended particulate matter (SPM) in Nanjing section of Yangtze River over a year (the flow period, the wet period and the dry period). All target compounds were detected at least once in surface water with 4-tert-butylphenol (4-TBP), nonyphenol (NP) and bisphenol A (BPA) as the dominant compounds, with concentrations in the range of 225-1121ng/L, 1.4-858ng/L and 1.7-563ng/L, respectively. Except for December, all selected compounds for the other sampling times were not found in all sampling points. NP (mean concentration 69.8µg/g) and BPA (mean concentration 51.8µg/g) were also the dominant estrogens in SPM. In addition, the highest total compounds concentrations were found in December in both phases, which could be due to the low flow conditions and temperature during this season. Meanwhile, a significant positive correlation was found between the total compounds concentrations in the water phase and those in SPM phase. Risk assessment based on the calculated risk quotients (RQ) showed that low and moderate risk for the aquatic environment from presence of the target compounds at all sampling points with exception of 4-TBP and NP which might pose a high risk to aquatic organisms.

[Analysis of Lymphocyte Subsets in Peripheral Blood of Patients with Aplastic Anemia or Hypoplastic Myelodysplastic Syndrome]

OBJECTIVE

To explore the ratio of lymphocyte subsets in peripheral blood of patients with aplastic anemia (AA) and patients with hypoplastic myelodysplastic syndrome (hypo-MDS) patients and to evaluate their significance.

METHODS

The clinical data of 181 cases of AA and 111 cases of hypo-MDS from January 2008 to December 2014 were collected from Blood Diseases Hospital of Chinese academy of medical sciences, and then the differences of lymphocyte subsets and its effect in 2 groups were analyzed.

RESULTS

CD4⁺/CD8⁺ ratio, proportion of CD3⁺ cells and its subsets CD3⁺CD4⁺/CD3⁺CD8⁺ cells in hypo-MDS group were not significant different from AA group (P>0.05). the proportion of CD3^-CD16/CD56⁺ NK cells and CD3⁺CD57⁺T-LGL cells in hypo-MDS group was significantly higher than that in AA group (P<0.05, P<0.01), but CD19⁺ B lymphocyte percentage in hypo-MDS patients was lower than that in AA patients (P<0.05). After dividing group according to CD4⁺/CD8⁺ ratio, the ratios of CD3⁺ CD16/CD56⁺ NK cells and CD3⁺/CD57⁺ T-LGL cells were higher only in normal CD4⁺/CD8⁺ ratio group of hypo-MDS patients than those in AA patients, while the ratio of B lymphocytes was significant different in inverted CD4⁺/CD8⁺ ratio group between hypo-MDS and AA patients. The CD19⁺ B lymphocyte ratio in hypo-MDS patients was significantly lower than that in AA patients (P<0.05). As well, the levels of erythrocytes and platelets in peripheral blood between hypo-MDS and AA patients only in normal CD4⁺/CD8⁺ ratio group were significantly different, while the significant difference of WBC count and reticulocyte ratio were observed in high CD4⁺/CD8⁺ ratio and non-inverted CD4⁺/CD8⁺ ratio groups, respectively; the significant difference of bone marrow blast ratio and muture monocyte ratio was found in high CD4⁺/CD8⁺ ratio group.

CONCLUSION

The changes of lymphocyte subsets can be used as an reference indicator for differential diagnosis of hypo-MDS and AA. The comparative analysis of patients with these 2 kinds of diseases after dividing into subgroups according to ratio of CD4⁺/CD8⁺ cells is beneficial to differentiat diagnosis.

Intracellular Biosynthesis of Fluorescent CdSe Quantum Dots in Bacillus subtilis: A Strategy to Construct Signaling Bacterial Probes for Visually Detecting Interaction Between Bacillus subtilis and Staphylococcus aureus

In this work, fluorescent Bacillus subtilis (B. subtilis) cells were developed as probes for imaging applications and to explore behaviorial interaction between B. subtilis and Staphylococcus aureus (S. aureus). A novel biological strategy of coupling intracellular biochemical reactions for controllable biosynthesis of CdSe quantum dots by living B. subtilis cells was demonstrated, through which highly luminant and photostable fluorescent B. subtilis cells were achieved with good uniformity. With the help of the obtained fluorescent B. subtilis cells probes, S. aureus cells responded to co-cultured B. subtilis and to aggregate. The degree of aggregation was calculated and nonlinearly fitted to a polynomial model. Systematic investigations of their interactions implied that B. subtilis cells inhibit the growth of neighboring S. aureus cells, and this inhibition was affected by both the growth stage and the amount of surrounding B. subtilis cells. Compared to traditional methods of studying bacterial interaction between two species, such as solid culture medium colony observation and imaging mass spectrometry detection, the procedures were more simple, vivid, and photostable due to the efficient fluorescence intralabeling with less influence on the cells' surface, which might provide a new paradigm for future visualization of microbial behavior.

Fluorescent yeast containing intracellularly biosynthesized CdSe QDs as a sensitive probe for simple determination of copper(ii) in water and plasma

CdSe QDs were attentively biosynthesized in yeast, and these yeasts can be used as a fluorescent probe for tracing Cu²⁺in water and plasma.

Crucial factors in biosynthesis of fluorescent CdSe quantum dots in Saccharomyces cerevisiae

Simple, controllable and repeatable procedures to biosynthesize CdSe in Saccharomyces cerevisiae are systematically demonstrated.

[Identification of the related substances in docetaxel injection by LC-MS/MS]

The related substances in docetaxel injection were identified by LC-MS/MS. Ethyl acetate was used to extract the injection to remove the pharmaceutical excipients. HPLC separation was carried out on a Hedera ODS-2 column (150 mm x 2.1 mm, 5 microm) with a mobile phase consisting of acetonitrile - 0.1% acetate acid aqueous solution (40: 60). Electrospray ionization source was set in the positive mode for the LC-ESI-MS/MS, and the ion monitoring modes were full scan and product ion scan. According to the mass spectra of the related substances, the fragment profiles were explained, and the chemical structures were elucidated. Docetaxel and its main related substances were well separated. Nine related substances in docetaxel injection were detected by LC-MS/MS. Their chemical structures were proposed, and four of them were identified in the docetaxel injection for the first time. The established LC-MS/MS method is effective in the separation and identification of the related substances in docetaxel injection. The test results are useful for its quality control.

Management of diaphragmatic rupture from blunt trauma

INTRODUCTION

Diagnosis of diaphragmatic rupture is difficult, and delays could result in a catastrophic outcome. We reviewed our institution's management of patients with diaphragmatic rupture after blunt trauma.

METHODS

All patients in this study were treated at Tan Tock Seng Hospital, Singapore, from March 2002 to October 2008. Patients with penetrating injuries were excluded. The parameters included age, mechanism of injury, haemodynamic status at admission, Glasgow coma scale (GCS) score, injury severity score (ISS), imaging studies, location of diaphragmatic injuries, associated injuries and outcome.

RESULTS

14 patients with a median age of 38 years formed the study group. Vehicular-related incidents accounted for 71.4 percent of the injuries. The median GCS score on admission was 14 (range 3-15), while the median systolic blood pressure and heart rate were 94 (range 50-164) mmHg and 110 (range 76-140) beats per minute, respectively. The median ISS was 41 (range 14-66). All had chest radiographs performed in the emergency department, six (42.9 percent) had computed tomography performed before surgery, while the remaining eight (57.1 percent) were sent straight to the operating theatre from the emergency department. There were five (35.7 percent) right-sided and nine (64.3 percent) left-sided diaphragmatic ruptures. The mortality rate was 35.7 percent. Some of the associated injuries included eight (57.1 percent) splenic lacerations, five (35.7 percent) haemothorax and lung injuries, four (28.6 percent) bone fractures and three (21.4 percent) liver lacerations. 12 (85.7 percent) patients underwent repair of the diaphragmatic rupture using interrupted polypropylene suture, while the remaining two (14.3 percent) were too haemodynamically unstable to undergo definitive treatment. Advanced age, haemodynamic instability and raised ISS were associated with mortality.

CONCLUSION

An accurate diagnosis of diaphragmatic rupture in trauma patients is difficult, and a thorough examination of both the hemidiaphragms is mandatory during emergency laparotomy for these patients. Those with more severe injuries and decreased physiological reserves usually fare worse.

Primary chordoma in the nasal cavity and nasopharynx: CT and MR imaging findings

BACKGROUND AND PURPOSE

Primary chordoma in the nasal cavity and nasopharynx is an extremely rare tumor in the extraosseous axial skeleton. Unlike intracranial chordomas, lesions in these sites primarily present as a soft tissue mass without involvement of the skull base bone (clivus), so the preoperative diagnosis of the tumor is possibly difficult. Here, we reviewed the imaging features of 5 cases of chordomas in the nasal cavity and nasopharynx that resulted in successful diagnosis and differential diagnosis of this rare tumor.

MATERIALS AND METHODS

We retrospectively studied 5 patients with histologically proven chordomas in the nasal cavity and nasopharynx. The lesion features of CT and MR imaging were reviewed, with emphasis on the size, shape, location, margin, calcification, CT attenuation characteristics, signal intensity, and degree of MR imaging enhancement.

RESULTS

Expansible and lobular soft tissue masses were mainly present, with irregular intratumor calcification in all 5 cases on CT examination. MR imaging revealed a well-defined tumor with heterogeneous signal intensity in 4 patients, whereas homogeneous signal intensity in 1 patient was present on all pulse sequences. Four cases of nasopharyngeal mass showed mild to moderate heterogenous enhancement. Intratumor septa could be seen in 2 cases.

CONCLUSIONS

Although no imaging features are pathognomonic, primary chordomas without skull base (clivus) bony changes in the nasal cavity and nasopharynx have some CT and MR imaging findings that are suggestive of diagnosis. The differential diagnosis of the soft tissue mass should be limited to these sites.

[Determination of Norfloxacin by its enhancement effect on the fluorescence intensity of functionalized CdS nanoparticles]

A novel assay of Norfloxacin with a sensitivity at the microgram level is proposed based on the measurement of enhanced fluorescence intensity signals by the interaction of functionalized nano-CdS with Norfloxacin. The CdS nanoparticles were synthesized by thioacetamide (TAA) and cadmium nitrate (Cd(NO3)2) in the alkaline solution, and the nanoparticles proved to be stable in the aqueous solution. At pH 7.4, the fluorescence signals of functionalized nano-CdS were greatly enhanced by Norfloxacin in the region of 300-700 nm characterized by the peak around 495 nm, and the surface defect-related emission located at 565 nm. However, the surface defect-related emission was unconspicuous, thus we concluded that the functionalized nano-CdS QDs (Quantum Dots) possessed excellent luminescence capability and favourable structure. At the same time, the absorption spectra and transmission electron microscopy (TEM) also proved this deduction. The external reaction conditions (such as effect of buffer system, pH, ionic strength, reaction time and temperature, colloid concentration) were discussed. The result showed that better fluorescence signals could be obtained in the condition of 0.10 mol x L(-1) Tris-HCl, pH 7.4, 0.1 mol x L(-1) NaCl and the reaction time 5 min. The fluorescence emission spectra of CdS QDs with increasing Norfloxacin concentration were recorded under the optimal condition. From the fluorescence intensity and peak position of nano-CdS colloidal as different concentration of Norfloxacin was added, the possible mechanism of reaction between mercapto-acetic acid capped CdS and Norfloxacin was discussed. Linear relationship can be established between the enhanced fluorescence intensity and Norfloxacin concentration in the range of 1.25-11.25 microg x mL(-1) (3.92-35.27 micromol x L(-1)) or 11.25-100.0 microg x mL(-1) (35.27-313.5 micromol x L(-1)). The limit of detection is 1.5 x 10(-3) x microg x mL(-1), which can be applied to the determination of blood serum samples. Based on this, a new direct quantitative determination method for Norfloxacin in synthetic samples without separation of foreign substances is established. At the same time, the possible enhancing mechanism is due to the formation of exciplex during reaction between nano-CdS and Norfloxacin, providing a guidance for the study of pharmacokinetics.

A novel fluorescent assay for edaravone with aqueous functional CdSe quantum dots

Aqueous thiol-capped CdSe QDs with a narrow, symmetric emission were prepared under a low temperature. Based on the fluorescence enhancement of thiol-stabilized CdSe quantum dots (QDs) caused by edaravone, a simple, rapid and specific quantitative method was proposed to the edaravone determination. The concentration dependence of fluorescence intensity followed the binding of edaravone to surface of the thiol-capped CdSe QDs was effectively described by a modified Langmuir-type binding isotherm. Factors affecting the fluorescence detection for edaravone with thiol-stabilized CdSe QDs were studied, such as the effect of pH, reaction time, the concentration of CdSe QDs and so on. Under the optimal conditions, the calibration plot of C/(I-I(0)) with concentration of edaravone was linear in the range of (1.45-17.42) microg/mL (0.008-0.1 micromol/L) with correlation coefficient of 0.998. The limit of detection (LOD) (3sigma/kappa) was 0.15 microg/mL (0.0009 micromol/mL). Possible interaction mechanism was discussed.

Determination of ciprofloxacin with functionalized cadmium sulfide nanoparticles as a fluorescence probe

A novel assay of ciprofloxacin with a sensitivity at the microgram level is proposed based on the measurement of enhanced fluorescence intensity signals resulting from the interaction of functionalized nano-CdS with ciprofloxacin. The CdS nanoparticles was synthesized by thioacetamide (TAA) and cadmium nitrate (Cd(NO(3))(2)) in the alkaline solution. At pH 7.4, the fluorescence signals of functionalized nano-CdS were greatly enhanced by ciprofloxacin with the increase concentration of ciprofloxacin. Linear relationship can be established between the enhanced fluorescence intensity and ciprofloxacin concentration in the range of (1.25-8.75)x10(-4) mg mL(-1) ((3.77-26.4) x 10(-4)mmol L(-1)) or (8.75-1200) x 10(-4)mg mL(-1) ((26.4-3625) x 10(-4) mmol L(-1)). The limit of detection is 7.64 x 10(-6) mg mL(-1) (2.31 x 10(-5)mmol L(-1)). Based on this, a new direct quantitative determination method for ciprofloxacin in human serum samples without separation of foreign substances was established. The contents of ciprofloxacin in human serum samples were determined with recovery of 95-105% and relative standard deviation (R.S.D.) of 1.5-2.5%. This method was proved to be very sensitive, rapid, simple and tolerance of most interfering substances.

[Synthesis and spectral studies of functionalized L-Cys-CdS nanoparticles as fluorescence probes]

In this work, nano-CdS was successfully prepared. The nano-CdS was also modified with L-cysteine. Absorption and fluorescence spectra of CdS nanoparticles for different pH values, reaction times and different Cys/Cd2+/S ratios were investigated. Meanwhile a fluorescence enhancing effect was observed between trace zinc ions and the functionalized L-Cys-CdS nanoparticles. The response is linearly proportional to the concentration of zinc ions from 1.0 to 15 micromol x L(-1). The functionalized nanoparticles are hopeful of use as fluorescence probes in detecting trace elements in biological samples.

[Studies on the reaction of balofloxacin with bovine serum albumin]

In the present paper, a fluorescence method was used to study at different pH the fluorescence quenching of bovine serum albumin (BSA) by its interaction with balofloxacin (BLFX). The interaction association constants of BSA and BLFX were determined from a double reciprocal line Weaver-Burk plot. According to the Forster dipole-dipole energy transfer, the distance to be measured between the BLFX and tryptophane is 5.09 nm. From thermodynamical coordination it can be judged that the binding power between BLFX and BSA is electrostatic effect. The effect of BLFX on the conformation of BSA was also analyzed by using synchronous fluorescence spectroscopy.

Development of neurotrophic molecules for treatment of neurodegeneration

Over the past several years, neurotrophic factors have made considerable progress from the laboratory into the clinic. Evidence from preclinical and clinical studies indicates that it may be possible to use neurotrophic factors to prevent, slow the progression of, or even reverse the effects of a number of neurodegenerative diseases and other types of insults in both the central and peripheral nervous system. Their potential importance in the development of therapeutic agents against neurodegenerative disorders and nerve injury has led to a flurry of activity towards understanding their structure, function and signalling mechanisms. Approaches to develop pharmacological agents that target neurotrophic factors, their receptors or neurotrophic factors signalling pathways have been attempted. This review focuses on some of the major themes and lines of mechanistic and therapeutic advances in this fast-moving field of neuroscience.

Influence of neuraminidase on the characteristics of microrheology of red blood cells

Surface charge was removed from RBC (erythrocyte) membrane to different degrees with biochemical methods, i.e., treatment of RBCs with neuraminidase, either using different doses for the same incubation time (1 hour) or using the same dose (75 milli-unit) for different incubation time. Several rheological properties of the RBCs with surface charge removal were observed, including the deformation index DI (using traditional ektacytometry) orientation index (DI)or and small deformation index (Dl)d (using new ektacytometry), the viscosity at low and high shear rates (using a cone-plate rotating viscosimeter). In addition, photographs of RBCs aggregation under a microscope and the histograms of RBC aggregate size after treatment with neuraminidase were obtained. It is found from these experiments that the decrease of the surface charge of RBCs leads to the decrease in the deformation and orientation indices as well as the increase in blood viscosity.

A study of hemorheological behaviour for patients with Alzheimer's disease at the early stages

To evaluate the change of hemorheological indexes for patients with Alzheimer's disease (AD) at the early stages and to discuss effects of these changes on AD, high shear value of whole blood viscosity (etabh), reduced high shear value of whole blood viscosity (retabh), low shear value of whole blood viscosity (etabl), reduced low shear, value of whole blood viscosity (retabl), KT value of whole blood viscosity, hematocrit (HCT) and blood plasma viscosity (etaP) were measured in 31 patients with probable AD at the early stages and 33 age-matched healthy subjects. There were significant differences of all hemorheological indexes between AD group and control group except HCT. Step discriminant analysis revealed 81.25% of overall group-classified accuracy in a hemorheological discriminant function consisting of etabl, retabl, retabh and HCT. Significant difference of hemorheological indexes existed between AD and age-matched healthy control subjects. The results showed that measurement of hemorheological indexes could be used as one of reference standards of diagnosis in AD.

Effects of morphine on rheological properties of rat red blood cells

To evaluate the effect of morphine on red blood cells, in vivo and in vitro rat models of morphine dependence were established. Rheological properties of rat red cells were measured by ektacytometry; the biophysical changes in the membrane of rat red cells were measured by the Fourier-Transformed Infrared technique (FT-IR) and the fluorescence depolarization method. The results show that the membrane fluidity of red cells was greatly reduced by morphine and the secondary structure of membrane proteins was changed. This suggests that morphine affects the rat red cell membrane directly, rather than through opioids-receptors.

Allelic imbalance at the LKB1 (STK11) locus in tumours from patients with Peutz-Jeghers' syndrome provides evidence for a hamartoma-(adenoma)-carcinoma sequence

Patients with Peutz-Jeghers' syndrome (PJS) develop hamartomatous gastrointestinal polyps and characteristic pigmentation, as a result of germline mutations in the LKB1 gene. The hamartomas in PJS were long considered to be without malignant potential. There is, however, accumulating epidemiological evidence to suggest that PJS predisposes to cancers at several different sites (colon, pancreas, breast, ovary, testis, and cervix), although large enough patient samples are rarely available to prove this. Allelic imbalance [allele loss, loss of heterozygosity (LOH)] has previously been reported in a small number of PJS polyps, suggesting that LKB1 acts as a tumour suppressor in these tumours. This study confirms allelic loss at LKB1 in PJS polyps and shows that LOH also occurs in cancers of the colon, breast, and cervix in PJS patients. Allele loss was additionally found in a colonic adenoma from a PJS patient, strongly suggesting the existence of a hamartoma-(adenoma)-carcinoma sequence in tumourigenesis. These results provide molecular evidence that PJS patients are predisposed to cancers at several sites, as a direct result of selection for loss of the 'wild-type' LKB1 allele in tumours. Given the rare involvement of LKB1 in sporadic cancers, these data also suggest that the indirect effect on cancer risk (or 'bystander effect') proposed for hamartomas in juvenile polyposis does not apply to carcinomas in PJS.

Germline mutations of the LKB1 (STK11) gene in Peutz-Jeghers patients

Germline mutations of the LKB1 (STK11) serine/threonine kinase gene (chromosome 19p13.3) cause Peutz-Jeghers syndrome, which is characterised by hamartomas of the gastrointestinal tract and typical pigmentation. Peutz-Jeghers syndrome carries an overall risk of cancer that may be up to 20 times that of the general population. Here, we report the results of a screen for germline LKB1 mutations by DNA sequencing in 12 Peutz-Jeghers patients (three sporadic and nine familial cases). Mutations were found in seven (58%) cases, in exons 1, 2, 4, 6, and 9. Five of these mutations, two of which are identical, are predicted to lead to a truncated protein (three frameshifts, two nonsense changes). A further mutation is an in frame deletion of 6 bp, resulting in a deletion of lysine and asparagine; the second of these amino acids is conserved between species. The seventh mutation is a missense change in exon 2, converting lysine to arginine, affecting non-conserved amino acids and of uncertain functional significance. Despite the fact that Peutz-Jeghers syndrome is usually an early onset disease with characteristic clinical features, predictive and diagnostic testing for LKB1 mutations will be useful for selected patients in both familial and non-familial contexts.

Allelic imbalance at the LKB1 (STK11) locus in tumours from patients with Peutz-Jeghers' syndrome provides evidence for a hamartoma-(adenoma)-carcinoma sequence

Patients with Peutz-Jeghers' syndrome (PJS) develop hamartomatous gastrointestinal polyps and characteristic pigmentation, as a result of germline mutations in the LKB1 gene. The hamartomas in PJS were long considered to be without malignant potential. There is, however, accumulating epidemiological evidence to suggest that PJS predisposes to cancers at several different sites (colon, pancreas, breast, ovary, testis, and cervix), although large enough patient samples are rarely available to prove this. Allelic imbalance [allele loss, loss of heterozygosity (LOH)] has previously been reported in a small number of PJS polyps, suggesting that LKB1 acts as a tumour suppressor in these tumours. This study confirms allelic loss at LKB1 in PJS polyps and shows that LOH also occurs in cancers of the colon, breast, and cervix in PJS patients. Allele loss was additionally found in a colonic adenoma from a PJS patient, strongly suggesting the existence of a hamartoma-(adenoma)-carcinoma sequence in tumourigenesis. These results provide molecular evidence that PJS patients are predisposed to cancers at several sites, as a direct result of selection for loss of the 'wild-type' LKB1 allele in tumours. Given the rare involvement of LKB1 in sporadic cancers, these data also suggest that the indirect effect on cancer risk (or 'bystander effect') proposed for hamartomas in juvenile polyposis does not apply to carcinomas in PJS.

Allele loss and mutation screen at the Peutz-Jeghers (LKB1) locus (19p13.3) in sporadic ovarian tumours

Germline mutations in the LKB1 (STK11) gene (chromosome sub-band 19p13.3) cause characteristic hamartomas and pigmentation to develop in patients with Peutz-Jeghers syndrome. Peutz-Jeghers syndrome carries an overall risk of cancer that may be up to 20 times that of the general population and Peutz-Jeghers patients are at increased risk of benign and malignant ovarian tumours, particularly granulosa cell tumours. Loss of heterozygosity (allele loss, LOH) has been reported in about 50% of ovarian cancers on 19p13.3. LKB1 is therefore a candidate tumour suppressor gene for sporadic ovarian tumours. We found allele loss at the marker D19S886 (19p13.3) in 12 of 49 (24%) sporadic ovarian adenocarcinomas. Using SSCP analysis, we screened ten ovarian cancers with LOH, 35 other ovarian cancers and 12 granulosa cell tumours of the ovary for somatic mutations in LKB1. No variants were detected in any of the adenocarcinomas. Two mutations were detected in one of the granulosa cell tumours: a mis-sense mutation affecting the putative 'start' codon (ATG --> ACG, M1T); and a silent change in exon 7 (CTT --> CTA, leucine). Like BRCA1 and BRCA2, therefore, it appears that LKB1 mutations can cause ovarian tumours when present in the germline, but occur rarely in the soma. The allele loss on 19p13.3 in ovarian cancers almost certainly targets a different gene from LKB1.

An animal model to study erythrocyte senescence with a narrow time window of erythrocyte production: alterations in osmotic fragility and deformability of erythrocytes during their life span

Using the model in which the entire RBC population was nearly synchronously produced following the induction of spherocytic anemia in the rabbit with antibody serum, we determined the changes of RBC osmotic fragility and deformability with aging. The results showed that the osmotic fragility increased with the RBC aging process in a nonlinear manner, being much more profound in the later part of the RBC life span. The RBC deformation index (DI) was measured by an ektacytometry. It is found that the DI decreased with RBC aging in a nonlinear fashion, with increasingly greater changes in the later part of the RBC life span. The alterations of RBC mechanical properties with aging may be attributable to a number of factors, including changes of RBC size and shape, and the viscoelasticity of the cytoplasm and membrane.

An animal model to study erythrocyte senescence with a narrow time window of erythrocyte production

Using the method of inducing spherocytic anemia in the rabbit with antibody serum, we have developed an animal model in which red blood cells (RBCs) can nearly grow synchronously. With this model, we determined that the surface charge density on the RBC membrane decreased with cell aging. The change was not linear, being much more profound in the latter half of RBC life span. There was a positive correlation between the mean RBC density and its "age" (r = 0.847, p < 0.01). However, the density distribution of the RBCs at the same "age" showed a broad range, and the density values for RBC groups with different ages showed considerable overlap. This indicates that the density gradient technique can be used to separate RBC population into fractions with different mean ages, but has a low resolving power for obtaining individual RBCs of a given "age".

A study of effects of WGA and ConA on RBC membrane receptors using a new ektacytometric method

With a new ektacytometry, we studied the relation between the microstructure of red blood cell (RBC) membrane and the rheological properties of RBCs in a shear flow field of low viscosity. The main contributions of this paper are as follows: 1. The hemorheological meanings of the orientation index (DI)or and the small deformation index (DI)d were explored. (DI)or is an overall rheological index depending on the deformability and morphology of RBCs. The better the physiological shape of RBCs is maintained, the greater the (DI)or is. (DI)d can be used to describe the lipid fluidity of RBC membrane. Such an explanation for the meaning of (DI)d has been forcefully supported by our experiments using electron spin resonance (ESR) and fluorescence polarization. 2. The influence of wheat germ agglutinin (WGA) of different concentrations on the lipid fluidity of membrane is different from that of concanavalin A (ConA). The lipid fluidity of membrane changes with WGA concentration treating RBCs and there is a maximum value for the membrane fluidity at a specific concentration of WGA. However, the deformability of membrane described by the integrate deformation index (IDI) monotonically decreased with the increase in WGA concentration treating RBCs. 3. It is concluded that the increase in the lipid fluidity of red cell membrane is not necessarily associated with the improvement of RBC deformability.

Bacterial scavengase p20 is structurally and functionally related to peroxiredoxins

Scavengase p20 was recently identified as a novel family of bacterial antioxidant enzymes possessing thioredoxin-linked thiol peroxidase activity. In this study, the Escherichia coli gene coding for scavengase p20 was isolated from three different strains and the nucleotide sequence was determined. Multiple alignment of amino acid sequence revealed that a previously unidentified Cys-61 is most conserved among all bacterial p20 scavengases and corresponds to the active site in the well-characterized peroxiredoxins. Phylogenetic analysis further supported that scavengase p20 is a novel subfamily of peroxiredoxins. Site-directed mutagenesis studies demonstrated that Cys-61 is indispensable for the antioxidant activities of scavengase p20. Taken together, our findings strongly suggest that the p20 scavengases are structurally and functionally related to peroxiredoxins.

Scavengase p20: a novel family of bacterial antioxidant enzymes

A novel antioxidant enzyme designated scavengase p20 was identified in various pathogenic bacteria through database searching for sequences strikingly homologous to a recently discovered Escherichia coli thiol peroxidase p20. The direct biochemical evidence for the existence of scavengase p20 in Haemophilus influenzae, Streptococcus pneumoniae and Helicobacter pylori was provided by protein microsequencing and by in vitro assays for antioxidant activities. Overlapping genes encoding scavengase p20 and superoxide dismutase were recognized in H. pylori and their functional implications are discussed.

Ischemia/reperfusion alters uric acid and ascorbic acid levels in liver

Tissue damage in ischemia/reperfusion injury may be mediated by oxidative stress caused by reactive oxidant species. Since such reactive species are difficult to measure directly, changes in antioxidant concentrations are often used as an indication of oxidative stress. In this study, microdialysis membranes were inserted into the livers of anesthetized rats to determine the effects of ischemia/reperfusion on the extra-cellular concentrations of two antioxidants, uric acid and ascorbic acid. Total hepatic ischemia was induced for 30 min by clamping the portal triad and was followed by 60 min of reperfusion. Uric acid and ascorbic acid concentrations were measured in microdialysis perfusates by high-performance liquid chromatography with electrochemical detection. Initial uric acid and ascorbic acid concentrations were high after insertion of membranes into the liver and decreased rapidly within 90 min (P < 0.001; ANOVA with repeated measures). Uric acid concentrations increased over 300% after ischemia and by 600% during the first 30 min of reperfusion (n = 8; P < 0.05). Ascorbic acid concentrations were 60% higher than controls after ischemia and 90% higher during the first 30 min of reperfusion (n = 8; P < 0.05). Alterations in concentrations of these redox-active molecules may be associated with oxidative stress in liver extracellular fluid during ischemia/reperfusion.

Nitric oxide attenuates endothelin-1-induced vasoconstriction in canine stomach

We previously observed that endothelin-1 (ET-1)-induced gastric vasoconstriction is enhanced after ischemia-reperfusion. The purpose of our present study was to examine the role of nitric oxide in regulating ET-1-induced vasoconstriction under normal conditions and after ischemia-reperfusion. Using a mechanically perfused stomach segment from chloralose-anesthetized dogs, we examined 1) responses to NG-nitro-L-arginine methyl ester (L-NAME) alone and in combination with L-arginine, 2) whether L-NAME affects ET-1-induced vasoconstriction under normal conditions and after ischemia-reperfusion, and 3) if spermine NONOate {1,3-propanediamine-N-[4-1-(3-aminopropyl)-2-hydroxy-2-nitrosohydrazi no] butyl; a nitric oxide donor} attenuates the augmented response to ET-1 after ischemia-reperfusion. Our results show that 1) L-NAME significantly increased baseline vascular resistance and this response was reduced by L-arginine, 2) ET-1-induced vasoconstriction was enhanced by L-NAME, and 3) administration of spermine NONOate during reperfusion largely attenuated the vasoconstrictor response to ET-1 after ischemia-reperfusion. Our findings are consistent with the hypothesis that nitric oxide modulates responses to ET-1 under normal conditions, and loss of this vasodilator after ischemia-reperfusion results in an augmented response to ET-1.

NMR applications in complex food systems

The rheological and functional properties of food components are related to their molecular structure, morphology, and atomic mobilities. NMR provides a powerful tool for elucidating chemical structures, molecular conformations, and interactions of components in food systems. Quantitative analysis of sugars, fats, and other principal compounds in complex food systems was achieved by high-resolution liquid NMR. In addition to information available from liquid experiments, solids NMR experiments can reveal differences and changes in crystal packing of structures in food model systems. Interpretation of experimental results is enhanced by molecular modeling of key food compounds. Models for fat crystallization are carried out to enhance understanding of the molecular structures involved in the fat crystallization process. Recently, MRI has also shown significant impact on food science and technology. Some examples of NMR applications are given in this presentation.

Magnetic resonance imaging (MRI) of a cookie in comparison with time-lapse photographic analysis (TLPA) during baking process

Magnetic Resonance Imaging (MRI) has been used to study the baking of a cookie. The structural and dynamic changes occurring during baking have been monitored, including changes in the internal moisture saturations and distribution. The images reveal the moisture distribution is initially uniform, and during baking a gradient in moisture develops from the interior to the edge. Changes in physical dimensions calculated from the data are consistent with those obtained from time-lapsed photography.

Ischemia-reperfusion increases gastric motility and endothelin-1-induced vasoconstriction

The purpose of our study was to 1) examine the effect of ischemia-reperfusion on gastric vascular resistance and motility, 2) determine whether endothelin-1 (ET-1)-induced vasoconstriction is enhanced after ischemia-reperfusion, and 3) assess the effect of superoxide dismutase (SOD) on these ischemia-reperfusion-induced alterations. These experiments used a mechanically perfused ex vivo gastric segment of chloralose-anesthetized dogs. We first evaluated the effect of varying the duration of total ischemia on reperfusion-induced changes in gastric vascular resistance and motility. In other experiments, responses to ET-1 (10(-10) M) were compared before and after 30-min ischemia and 30-min reperfusion, with saline or SOD (10 U/ml) infused intra-arterially to the stomach during reperfusion. Our results show that 1) after ischemia, vasodilation is seen initially on reperfusion followed by a slowly developing, progressive increase in vascular resistance, 2) the force of gastric contractions was reduced during ischemia but elevated immediately on reperfusion, 3) vasoconstrictor responses to ET-1 are enhanced after ischemia-reperfusion, and 4) SOD reduced the enhanced response to ET-1 and force of contractions. Our findings support the hypothesis that reactive oxygen metabolites contribute to augmented vascular reactivity and hypercontractility after ischemia-reperfusion.

Role of prostaglandins in angiotensin II-induced gastric vasoconstriction

The purpose of our study was to examine the role of prostaglandins in angiotensin II (ANG II)-induced gastric vasoconstriction. ANG II produced statistically significant, dose-related increases in vascular resistance of a mechanically perfused ex vivo stomach segment of chloralose-anesthetized dogs. We next examined the effect of cyclooxygenase inhibitors on responses to ANG II. Indomethacin (10 mg/kg), which blocked the vasodilator response to intra-arterial arachidonic acid, augmented the maximal increase in perfusion pressure during ANG II infusion. Similar results were found using a different cyclooxygenase inhibitor, meclofenamic acid. In the final experiments we used an enzyme immunoassay to measure 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) plasma concentrations. ANG II produced dose-related increases in gastric venous but not arterial levels of 6-keto-PGF1 alpha, the major metabolite of prostacyclin. Our results are consistent with the hypothesis that release of vasodilatory prostaglandins attenuates the vasoconstrictor response to ANG II in the gastric microcirculation.