Meta-analysis of the effect of percutaneous coronary intervention on chronic total coronary occlusions

Background and purpose

Coronary chronic total occlusion (CTO) is the last stage of coronary artery atherosclerosis. Percutaneous coronary intervention (PCI) is a therapeutic procedure used to recanalize vessels with total occlusion. However, successful recanalization of CTO is still not optimal, and the key influence factors are still uncertainty. Therefore, a scientific evaluation on the effective of PCI for CTO treatment is necessary.

Methods

Relevant studies of PCI treatment for CTO were examined. Data were extracted and assessed by two independent clinical experts. Embase, PubMed and Medline et al. were used as database. The main research key words include “CTO”, “PCI”, “Stent”, “Reopen”, “long-term”, “follow-up” and “outcome”. Quality assessment was carried out according to the Cochrane Handbook. The selected data were pooled and analyzed using fixed-effect model and random-effect model. Heterogeneity was assessed using the I² test, Q test, L’abbe and Galbraith. Comprehensive Meta -Analysis 2.0 and Metanalysis 1.0 were used for statistics analysis in this research.

Results

A total of 16 articles involving 6695 cases in successful CTO recanalization (CTO success group) and 2370 cases in failed CTO recanalization(CTO failure group) were included in this research. Low CTO success was associated with elder age, previous coronary artery bypass graft surgery (CABG) history, multi-vessel diseases and right coronary artery disease lesion. Six follow-up variables including major adverse cardiac events (MACE), recurrent myocardial infarction (MI), all-cause death, incidence of angina, subsequent CABG and cumulative survival rate were found significantly reduced associated with CTO success.

Conclusions

Clinical baseline characteristics such as age, previous CABG history and lesion baseline characteristics such as lesion length, multi-vessel diseases might be important factors influencing the successful rate of CTO recanalization. Compared to CTO failure patients, all six follow-up variables showed advantage for CTO success patients.

Active role of the predecidual-like zone in endometrial shedding in a mouse menstrual-like model

Cyclic shedding of the endometrium is unique to menstruating species. The status of the decidua in mouse menstrual-like models seems to differ from that of the predecidua in humans before endometrial breakdown. The aim of this study was to determine how this difference in decidual status is related to endometrial breakdown. A mouse menstruallike model was generated by pharmacological progesterone withdrawal. Histomorphological analysis and reticular fiber staining were used to evaluate endometrial status. In situ zymography was used to determine the localization of active collagenase and gelatinase. The functional endometrial layer containing the mature decidual-like zone (MDZ) and predecidual-like zone (PZ) underwent breakdown. The reticular fibers underwent disruption and fragmentation and became loose or disappeared at 12 h in the PZ, where active collagenase and gelatinase were limited. The reticular fibers were visibly reduced at 24 h in the MDZ, where active collagenase was detected. A few reticular fibers remained; however, the functional layer had sloughed into the lumen of the uterus. The results showed that reticular fibers of the PZ are actively degraded during endometrial shedding.

ER stress-mediated apoptosis induced by celastrol in cancer cells and important role of glycogen synthase kinase-3β in the signal network

HeLa cells treated with celastrol, a natural compound with inhibitive effect on proteasome, exhibited increase in apoptotic rate and characteristics of apoptosis. To clarify the signal network activated by celastrol to induce apoptosis, both the direct target proteins and undirect target proteins of celastrol were searched in the present study. Proteasome catalytic subunit β1 was predicted by computational analysis to be a possible direct target of celastrol and confirmed by checking direct effect of celastrol on the activity of recombinant human proteasome subunit β1 in vitro. Undirect target-related proteins of celastrol were searched using proteomic studies including two-dimensional electrophoresis (2-DE) analysis and iTRAQ-based LC-MS analysis. Possible target-related proteins of celastrol such as endoplasmic reticulum protein 29 (ERP29) and mitochondrial import receptor Tom22 (TOM22) were found by 2-DE analysis of total cellular protein expression profiles. Further study showed that celastrol induced ER stress and ER stress inhibitor could ameliorate cell death induced by celastrol. Celastrol induced translocation of Bax into the mitochondria, which might be related to the upregulation of BH-3-only proteins such as BIM and the increase in the expression level of TOM22. To further search possible target-related proteins of celastrol in ER and ER-related fractions, iTRAQ-based LC-MS method was use to analyze protein expression profiles of ER/microsomal vesicles-riched fraction of cells with or without celastrol treatment. Based on possible target-related proteins found in both 2-DE analysis and iTRAQ-based LC-MS analysis, protein–protein interaction (PPI) network was established using bioinformatic analysis. The important role of glycogen synthase kinase-3β (GSK3β) in the signal cascades of celastrol was suggested. Pretreatment of LiCL, an inhibitor of GSK3β, could significantly ameliorate apoptosis induced by celastrol. On the basis of the results of the present study, possible signal network of celastrol activated by celastrol leading to apoptosis was predicted.

Sorafenib combined with transarterial chemoembolization for the treatment of advanced hepatocellular carcinoma: a large-scale multicenter study of 222 patients

BACKGROUND

Data on the efficacy and safety of sorafenib in combination with transarterial chemoembolization (TACE) in patients with advanced hepatocellular carcinoma (HCC) are lacking.

PATIENTS AND METHODS

In this multicenter retrospective study, 222 consecutive HCC patients receiving combination therapy were enrolled between June 2008 and July 2011.

RESULTS

Chronic hepatitis B was the predominant cause of HCC (86%). Eighty percent patients were at Barcelona Clinic Liver Cancer (BCLC) stage C, and 86% patients were in Child-Pugh (CP) A class. The overall median survival was 12 months (95% CI 10.1-13.9). The overall incidence of adverse events (AEs) was 87%. In 177 BCLC-C patients, performance status, the number of HCC nodules, Child-Pugh score and macrovascular invasion were significantly associated with overall survival (OS) and were included in the final risk scores (R), where R = 5 × (vascular invasion: 0 if no, 1 yes) + 6 × (CP: 0 if A, 1 if B) + 7 × (no. of lesions: 0 if 1-2, 1 ≥3) + 8 × ( Eastern Cooperative Oncology Group, ECOG: 0 if 0, 1 ≥1).

CONCLUSIONS

Sorafenib in combination with TACE should be considered a safe and effective therapy for advanced HCC. Further validation of the new subgroup of BCLC-C stage is warranted in an independent patient cohort.

Subinhibitory concentrations of pinocembrin exert anti-Staphylococcus aureus activity by reducing α-toxin expression

AIMS

Natural products have been used as potentially important sources of novel antibacterials in combating pathogenic Staphylococcus aureus isolates, a major problem around the world. In this study, we aimed to investigate the antibacterial effects of pinocembrin (PNCB) against Staph. aureus pneumonia in a murine model and its influence on the production of Staph. aureus α-haemolysin (Hla).

METHODS AND RESULTS

The in vitro activities of PNCB on α-haemolysin production were determined using haemolysis, Western blot and real-time RT-PCR assays. The viability and cytotoxicity assays were performed to evaluate the influence of PNCB on α-toxin-mediated injury of human alveolar epithelial cells. Moreover, through histopathologic analysis, we further determined the in vivo effects of PNCB on Staph. aureus pneumonia in a mouse model. In vitro, PNCB at low concentrations exhibited inhibitory activity against α-haemolysin production and attenuated α-haemolysin-mediated cell injury. Furthermore, the in vivo findings demonstrated that PNCB protected mice from Staph. aureus pneumonia.

CONCLUSIONS

We have provided new evidence of the effects of PNCB, which suggest that PNCB attenuated α-haemolysin-mediated cell injury and protected mice from Staph. aureus pneumonia.

SIGNIFICANCE AND IMPACT OF THE STUDY

The findings indicate that PNCB may be used as a basis for anti-Staphylococcus agent.

A study of circulating anti-CD25 antibodies in non-small cell lung cancer

PURPOSE

Tumors can trigger specific immune response to tumor-associated antigens but the precise mechanism remains unclear. Since regulatory T-lymphocytes (Treg) play a crucial role in controlling autoimmune responses, the present work was undertaken to test whether dysfunction of Treg cells could be involved in developing autoimmunity in patients with lung cancer.

METHODS

In this study, we developed an in-house enzyme-linked immunosorbent assay to test circulating anti-CD25 autoantibodies among 272 patients with non-small cell lung cancer (NSCLC) and 226 control subjects matched in age, gender and smoking history.

RESULTS

Mann-Whitney U test showed that the anti-CD25 IgG level was significantly higher in patients with NSCLC than control subjects (Z = -7.48, P < 0.001) while the anti-CD25 IgA level was not significantly changed in the patient group as compared with the control group (Z = -1.34, P = 0.181). Spearman correlation analysis failed to reveal a significant correlation between the levels of anti-CD25 IgG and IgA either in patients with NSCLC (r = -0.034, P = 0.578) or in control subjects (r = 0.055, P = 0.429). ROC analysis showed an AUC of 0.70 for anti-CD25 IgG, in which NSCLC at stage III had the highest AUC (0.75). The sensitivity against a specificity of >90 % was 35.0 % for anti-CD25 IgG assay with an inter-assay deviation of 9.4 %, and 4.0 % for anti-CD25 IgA assay with an inter-assay deviation of 13.0 %.

CONCLUSIONS

Circulating anti-CD25 IgG antibody may be a useful biomarker for prognosis of lung cancer.

Local thrombolysis for severe cerebral venous sinus thrombosis

BACKGROUND AND PURPOSE

Cerebral venous thrombosis is a rare entity that can be difficult to manage. Most patients with cerebral sinus thrombosis recover after treatment with heparin, but a subgroup of severe cerebral venous sinus thrombosis has a poor prognosis. Those patients may benefit from intrasinus thrombolysis. The purpose of this research was to carry out a retrospective analysis of patients with severe cerebral venous sinus thrombosis, and to study the safety and efficacy of intrasinus thrombolysis in patients with cerebral venous sinus thrombosis unresponsive to conventional heparin therapy.

MATERIALS AND METHODS

Thirty-seven patients with cerebral venous sinus thrombosis who received intrasinus thrombolysis during a 3-year period (January 2007 to December 2009) were included in this study. Urokinase was infused into the sinus via a microcatheter. Data regarding demographic, clinical, and radiologic features were collected. Follow-up data were obtained at 6 months. MRV was repeated to assess the recanalization of the venous sinus.

RESULTS

Twenty-seven patients (73%) had good outcome and 7 patients (19%) who were independent for activities of daily life had only mild deficits. One patient survived with severe neurologic deficits and 2 patients died. Complete recanalization of the superior sagittal sinus was seen in 35 patients (97%). At a follow-up of 6 months, 34 patients (92%) were either asymptomatic or had only minor subjective symptoms.

CONCLUSIONS

Intrasinus thrombolysis is safe and effective in patients with severe cerebral venous sinus thrombosis. However, the subgroup of patients that is likely to benefit the most from this procedure is not clear from our data. Large randomized controlled trials are required to further clarify this issue.

The effect of hierarchical micro/nanosurface titanium implant on osseointegration in ovariectomized sheep

Hydrofluoric etching and anodized hierarchical micro/nanotextured surface titanium implant was placed in mandibles of ovariectomized sheep for 12 weeks, and it showed improved osseointegration by resonance frequency analysis (RFA), microcomputed tomography (micro-CT) evaluation, histomorphometry, and biomechanical test.

INTRODUCTION

This study aimed to investigate the effects of micro/nanotextured titanium implant on osseointegration in ovariectomized (OVX) sheep.

METHODS

The hierarchical micro/nanotextured surface of titanium implant was fabricated by acid in 0.5% (w/v) hydrofluoric (HF) and anodized in HF acid electrolytes with a DC power of 20 V, and the machined surface implants with no treatment served as control group. The implants were placed in mandibles of OVX sheep, respectively. Twelve weeks after implantation, RFA, microcomputed tomography, histomorphometry, and biomechanical tests were applied to detect the osseointegration of the two groups.

RESULTS

The implant stability quotient (ISQ) values, the maximum pull-out forces, and the bone-implant contact (BIC) were 65.5 ± 6.3, 490.6 ± 72.7 N, and 58.31 ± 5.79% in the micro/nanogroup and 58.3 ± 8.9, 394.5 ± 54.5 N, and 46.85 ± 5.04% in the control group, respectively. There was no significant difference between the two groups in ISQ values (p > 0.05), but in the micro/nanogroup, the maximal pull-out force and the BIC were increased significantly (p < 0.05 or p < 0.01). Micro-CT analysis showed that the bone volume ratio and the trabecular number increased significantly (p < 0.01), and the trabecular separation decreased significantly (p < 0.05) in the micro/nanogroup.

CONCLUSION

Implant modification by HF acid etching and anodization to form a hierarchical micro/nanotextured surface could improve titanium implant osseointegration in OVX sheep 12 weeks after implantation.

Acute and chronic myocardial infarction in a pig model: utility of multi-slice cardiac computed tomography in assessing myocardial viability and infarct parameters

OBJECTIVES

The aim of this study was to determine the feasibility of multi-slice computed tomography (MSCT) biphasic imaging in assessing myocardial viability and infarct parameters in both acutely and chronically infarcted pig models.

MATERIALS AND METHODS

Seven pigs underwent ligation of the distal left anterior descending artery. Imaging was performed on the day of infarction and 3 months post-infarct, with contrast infusion followed by MSCT scan acquisition at different time-points. Left ventricular ejection fractions (LVEFs) were obtained by left ventriculography (LVG) after 3 months. Infarcted locations found using MSCT were compared with those obtained using SPECT. Infarcted areas were also analysed histopathologically and compared with the findings from MSCT.

RESULTS

Chronic phase images had perfusion defects with lower CT values relative to normal myocardium (43±10HU vs. 156±13HU, p=0.001) on the early images but no residual defects on delayed images. However, we found hyperenhancing regions on delayed images (244±20HU vs. 121±25HU, p=0.001), and good correlation between MSCT- and LVG-derived LVEFs (60.56±7.56%). The areas identified by MSCT corresponded to the location of (201)Tl SPECT-/pathologic staining-derived regions in all models. Infarct size was in good agreement with MSCT and pathological analyses of chronic phase models.

CONCLUSIONS

Necrotic myocardium in different stages after infarction could be qualitatively and quantitatively assessed using MSCT biphasic imaging, as could the status of microcirculation formation. MSCT-measured LVEFs matched well with other modalities, and hence MSCT is a useful tool in assessing post-infarct cardiac function.

Microbial strategies to control aflatoxins in food and feed

Aflatoxins are a group of toxic and carcinogenic fungal metabolites. They are commonly found in cereals, nuts and animal feeds and create a significant threat to the food industry and animal production. Several strategies have been developed to avoid or reduce harmful effects of aflatoxins since the 1960s. However, prevention of aflatoxin contamination pre/post harvest or during storage has not been satisfactory and control strategies such as physical removing and chemical inactivating used in food commodities have their deficiencies, which limit their large scale application. It is expected that progress in the control of aflatoxin contamination will depend on the introduction of technologies for specific, efficient and environmentally sound detoxification. The utilisation of biological detoxification agents, such as microorganisms and/or their enzymatic products to detoxify aflatoxins in contaminated food and feed can be a choice of such technology. To date, many of the microbial strategies have only showed reduced concentration of aflatoxins and the structure and toxicity of the detoxified products are unclear. More attention should be paid to the detoxification reactions, the structure of biotransformed products and the enzymes responsible for the detoxification. In this article, microbial strategies for aflatoxin control such as microbial binding and microbial biotransformation are reviewed.

Preparation, purification and characteristics of an aflatoxin degradation enzyme from Myxococcus fulvus ANSM068

AIMS

To prepare, purify and characterize an extracellular enzyme from Myxococcus fulvus ANSM068, designated as myxobacteria aflatoxin degradation enzyme (MADE), which possesses degradation activity against aflatoxin B(1) (AFB(1) ), G(1) (AFG(1) ) and M(1) (AFM(1) ) in solution.

METHODS AND RESULTS

The culture supernatant of strain M. fulvus demonstrated high degradation ability against AFB(1) (71·89%), AFG(1) (68·13%) and AFM(1) (63·82%) after 48 h of incubation. An enzyme was purified from the supernatant of M. fulvus using ethanol precipitation and chromatography on DEAE-Sepharose and Superdex 75. An overall 166-fold purification of the enzyme with a recovery of 57% and a final specific activity of 569·44 × 10(3) U mg(-1) was obtained using the present purification protocol. The apparent molecular mass of MADE was estimated to be 32 kDa by SDS-PAGE. AFG(1) and AFM(1) were significantly degraded, by 96·96 and 95·80%, respectively, when treated with pure MADE (100 U ml(-1) ) produced by strain ANSM068. MADE exhibited the largest amount of activity at 35°C and pH 6·0, with Mg(2+) ions greatly promoting and Zn(2+) strongly inhibiting MADE activity.

CONCLUSIONS

An aflatoxin DEGRADATION ENZYME FROM BACTERIAL ISOLATES CAN EFFECTIVELY REMOVE AFLATOXIN B(1) , G(1) AND M(1) IN SOLUTION.

SIGNIFICANCE AND IMPACT OF THE STUDY

The high activity and wide temperature and pH range of MADE for the degradation of aflatoxin have promising applications in control of mycotoxins during food and feed processing.

Partial splenic embolization for hypersplenism in cirrhosis: a long-term outcome in 62 patients

BACKGROUND

Although partial splenic embolization (PSE) has been widely used for treatment of leucocytopaenia and thrombocytopaenia in cirrhosis, only few studies on the correlation between splenic infarction rate and long-term outcome of partial splenic embolization have been reported so far.

AIM

To evaluate long-term results of partial splenic embolization with different infarction rates in cirrhotic patients with hypersplenism.

METHODS

Sixty-two consecutive patients with hypersplenism in cirrhosis received partial splenic embolization. According to the splenic infarction rate after partial splenic embolization, the patients were divided into three groups: more than 70% in group A (n=12), 50-70% in group B (n=34), and less than 50% in group C (n=16). The post-partial splenic embolization following-up time was 5 years.

RESULTS

Before partial splenic embolization, there were no significant differences among the three groups with respect to sex, age, splenic volume, Child-Pugh class, oesophageal varices, and peripheral blood cell counts. After partial splenic embolization, the short- and long-term outcomes of leucocyte and platelet counts showed significant difference among the three groups (P<0.001). In groups A and B, the leucocyte and platelet counts after partial splenic embolization remained significantly higher than those before partial splenic embolization for 2 weeks to 5 years (P<0.05), the post-partial splenic embolization leucocyte and platelet counts was even higher in group A than in group B; while in group C, leucocyte and platelet count improvement only lasted for 6 months after partial splenic embolization. No significant changes were observed concerning blood red cell counts and liver function parameters after partial splenic embolization among the three groups. Severe complications occurred in six patients (50%) in group A and three patients (8.8%) in group B (P<0.05), while in group C, no severe complications developed.

CONCLUSIONS

In partial splenic embolization, the splenic infarction rate should be limited to 50%-70% in order to ensure the long-term efficacy in alleviating hypersplenism and reduce complications.

Sulfopeptide fragmentation in electron-capture and electron-transfer dissociation

Sulfopeptides can be misassigned as phosphopeptides because of the isobaric nature of the sulfo- and the phosphomoieties. Instruments having the ability to measure mass with high accuracy may be employed to distinguish these moieties based on their mass defect (the sulfo-group is 9 mmu lighter than the phosphomoiety). However, the assignment of the exact site(s) of post-translational modification is required to probe biological function. We have reported earlier that peptides with identical sequences containing either O-sulfo- or O-phospho-modifications display different fragmentation behavior (K. F. Medzihradszky et al., Mol. Cell. Proteom.2004, 3, 429-440). We have also established that O-sulfo moieties are susceptible to side-chain fragmentation during collision-induced dissociation. Our present study provides evidence that neutral SO(3) losses can also occur in electron capture dissociation and electron-transfer dissociation experiments. We also report that such neutral losses may be reduced by fragmenting peptide-alkali metal adducts, such as sodiated or potassiated peptides.

Protocatechuic acid suppresses MPP+-induced mitochondrial dysfunction and apoptotic cell death in PC12 cells

Protocatechuic acid (PCA), a phenolic compound isolated from the kernels of Alpinia (A.) oxyphylla, showed antioxidant neuroprotective effect in our previous study. Here, we investigated the effect of PCA on the MPP(+)-induced mitochondrial dysfunction and apoptotic cell death in PC12 cells. The apoptosis in MPP(+)-induced PC12 cells was associated with loss of mitochondrial membrane potential, the formation of reactive oxygen species (ROS), GSH depletion, activation of caspase-3 and down-regulation of Bcl-2. In contrast, treatment of PC12 cells with PCA significantly prevented the above-mentioned mitochondrial dysfunction. Our data pointed to the potential clinical application/use of PCA to overcome neurodegenerative diseases such as Parkinson's disease.

Protocatechuic acid from Alpinia oxyphylla against MPP+-induced neurotoxicity in PC12 cells

An ethyl acetate extract of Alpinia oxyphylla was found to possess neuroprotective activity against 1-methyl-4-phenylpyridinium ion (MPP(+)) induced apotosis and oxidative stress in cultured PC12 cells. From the extract, a phenolic compound was isolated through bioassay-guided fractionation and identified as protocatechuic acid (PCA) by IR, MS, and (1)H and (13)C NMR spectroscopy. It was the first time which was isolated from the kernels of A. oxyphylla. Exposure of PC12 cells to 1mM MPP(+) may cause significant viability loss and apoptotic cell death. PCA stimulated PC12 cellular proliferation and markedly attenuated MPP(+)-induced apoptotic cell death in a dose-dependent manner. By observing the nuclear morphological changes and flow cytometric analysis, PCA showed its significant effect on protecting PC12 cells against MPP(+)-induced apoptosis. Meanwhile, PCA enhanced the activities of superoxide dismutase (SOD) and catalase (CAT) in PC12 cells. In addition, PCA also dose-dependently reduced the hydrogen peroxide (H(2)O(2))- or sodium nitroprusside (SNP)-induced cell death in PC12 cells. The results suggest that PCA may be one of the primary active components in the kernels of A. oxyphylla and provide a useful therapeutic strategy for the treatment of oxidative stress-induced neurodegenerative disease such as Parkinson's disease.

Characterization of Tetrahymena Histone H2B Variants and Posttranslational Populations by Electron Capture Dissociation (ECD) Fourier Transform Ion Cyclotron Mass Spectrometry (FT-ICR MS)

This work describes the nature and sequence information content of the electron capture dissociation mass spectra for the intact Tetrahymena histone H2B. Two major variants of this protein were present bearing nominal modifications of both +42 and +84 Da. This work describes identification of the nature of these two modifications. For example, using gas-phase selection and isolation of the +42-Da modified species, from a background of two H2B variants each present in six or more posttranslationally modified isoforms, we were able to determine that this +42-Da modification isoform bears trimethylation rather than acetylation. LC-CIDMS analysis was also employed on digested preparations to obtain complementary detail of the nature of site-specific posttranslational modifications. This study establishes that integration of the information from these two datasets provides a comprehensive map of posttranslational occupancy for each particular covalent assemblage selected for structural investigation.

Characterization of binding and utilization of hemoglobin by Prevotella nigrescens

The ability of Prevotella nigrescens to utilize and bind to hemoglobin was investigated. Growth studies showed that P. nigrescens was able to utilize hemoglobin efficiently as an iron source. Binding of P. nigrescens to hemoglobin was demonstrated by dot blot assay. Heat and trypsin treatments of the bacteria led to a decrease in activity. Globin gave nearly complete inhibition of activity. Additionally, lactoferrin partially inhibited activity. In contrast, transferrin, cytochrome C and catalase exerted little or no inhibitory effect. Although the sugars tested did not affect activity, several of the amino acids tested, including arginine, cysteine, histidine and lysine, inhibited activity. In a solid phase assay, 41-, 56- and 59-kDa proteins of P. nigrescens reacted with hemoglobin. These results suggest that P. nigrescens utilizes hemoglobin for growth and 41-, 56- and 59-kDa proteins may be involved in hemoglobin binding.

Effect of tetrandrine on cellular electrophysiology and calcium uptake of myocardium in guinea pigs and dogs

OBJECTIVE

To study the effects of tetrandrine, a Chinese herbal medicine, on the action potential (AP), contraction as well as sarcoplasmic reticulum (SR) calcium uptake of myocardium in guinea-pigs and dogs.

METHODS

Changes in AP, dV/dt, peak tension (PT) and dT/dt of myocardial cells were studied using the technique of glass electrode. Changes of the calcium uptake rate by sarcoplasmic reticulum and release of inorganic phosphate from sarcoplasmic reticulum were assessed with biochemical techniques.

RESULTS

Tetrandrine exerts a concentration-dependent and frequency-dependent negative inotropic effect and shortens action potential duration. Tetrandrine depresses both dT(E)/dt and dT(L)/dt as well as the tension of myocardium, and reduces dV/dt and amplitude only in the slow action potential, thus implying that tetrandrine blocks the slow calcium channel. In addition, compared with thapsigargin, a specific inhibitor of Ca(2+)-ATPase on SR, tetrandrine more apparently suppresses the contraction of the myocardium.

CONCLUSIONS

Tetrandrine is a wide-range calcium antagonist of plant origin. Not only it blocks the voltage-operated calcium channels as other authors reported, but also may play an important role in affecting the function of Ca(2+)-ATPase and calcium release channels on SR. From this study, we also suggest that the calcium channel appears to be more critical than SR for the contraction of myocardium.

Functional analysis of the galactosyltransferases required for biosynthesis of D-galactan I, a component of the lipopolysaccharide O1 antigen of Klebsiella pneumoniae

D-Galactan I is an O-antigenic polymer with the repeat unit structure [-->3)-beta-D-Galf-(1-->3)-alpha-D-Galp-(1-->], that is found in the lipopolysaccharide of Klebsiella pneumoniae O1 and other gram-negative bacteria. A genetic locus containing six genes is responsible for the synthesis and assembly of D-galactan I via an ATP-binding cassette (ABC) transporter-dependent pathway. The galactosyltransferase activities that are required for the processive polymerization of D-galactan I were identified by using in vitro reactions. The activities were determined with endogenous lipid acceptors in membrane preparations from Escherichia coli K-12 expressing individual enzymes (or combinations of enzymes) or in membranes reconstituted with specific lipid acceptors. The D-galactan I polymer is built on a lipid acceptor, undecaprenyl pyrophosphoryl-GlcpNAc, a product of the WecA enzyme that participates in the biosynthesis of enterobacterial common antigen and O-antigenic polysaccharide (O-PS) biosynthesis pathways. This intermediate is directed into D-galactan I biosynthesis by the bifunctional wbbO gene product, which sequentially adds one Galp and one Galf residue from the corresponding UDP-sugars to form a lipid-linked trisaccharide. The two galactosyltransferase activities of WbbO are separable by limiting the UDP-Galf precursor. Galactosyltransferase activity in membranes reconstituted with exogenous lipid-linked trisaccharide acceptor and the known structure of D-galactan I indicate that WbbM catalyzes the subsequent transfer of a single Galp residue to form a lipid-linked tetrasaccharide. Chain extension of the D-galactan I polymer requires WbbM for Galp transferase, together with Galf transferase activity provided by WbbO. Comparison of the biosynthetic pathways for D-galactan I and the polymannose E. coli O9a antigen reveals some interesting features that may reflect a common theme in ABC transporter-dependent O-PS assembly systems.

[Clinical observation of the microanatomical relation between pituitary stalk and pituitary adenoma]

OBJECTIVE

To observe the microanatomical relation between the pituitary stalk and pituitary adenoma so as to find practical approach to protect the pituitary stalk during operation.

METHODS

At the level of diaphragm sellae, the laterality of pituitary stalk was assessed in 71 cases by its location to the line connecting the mid-points of tuberculum sellae and dorsum sellae. In 46 cases the level of diaphragma sellae was regarded as the clock dial so as to determine the location by hour of the pituitary stalk.

RESULTS

The laterality of pituitary stalk was observed in 61 cases, among which the pituitary stalk was on the left side in 17 cases, on the right side in 41 cases, and at the posterior middle site in 13 cases. Location by hour was observed in 46 cases, among which 13 cases were at 5 o'clock, 11 at 6 o'clock, 7 at 7 o'clock, 5 at 4 o'clock, 4 at 3 o'clock, 2 at 2 o'clock, 2 at o'clock, and 2 at 11 o'clock respectively.

CONCLUSION

The location of pituitary stalk is related to the direction of growth of tumor in the sella and not related to its extension above the sella. The pituitary stalk can be used as the marker to find normal pituitary tissue.

[Anatomicopathological relation between facial nerve and large vestibular Schwannoma]

OBJECTIVE

To study the anatomicopathological relation between facial nerve and large vestibular schwannoma.

METHODS

Operation by suboccipital retrosigmoid sinus approach was performed on 40 cases with large vestibular schwannoma, During the operation, the anatomicopathological relation between the facial nerve and the vestibular schwannoma was observed directly.

RESULTS

The facial nerve was found to be located ventrally (deep under the tumor), dorsally (over the tumor), at the upper pole of the tumor (near the tentorium cerebelli), at the lower pole of the tumor (near the rear group cranial nerves), or aberrant (unable to be identified because of infiltration of tumor). In 31 cases, mainly with parenchymatous tumor, the facial nerve was flat in shape. In 9 cases, mainly with cystic tumor, the facial nerve was bandlike.

CONCLUSION

The facial nerve varies greatly in neuroanatomy among patients with large vestibular schwannoma. Strengthening of operative monitoring can increase the safety of operation.

[Detection of fetal cells in maternal blood by fluorescence in situ hybridization]

OBJECTIVE

To isolate fetal nucleated cells from maternal blood and determine its fetal origin.

METHODS

Enrichment and isolation of nucleated cells in maternal blood from 20 samples in the first trimester of pregnancy, 20 samples in the mid-trimester of pregnancy, and 15 samples after delivery. Fluorescence in situ hybridization was performed using Y specific probe PY3.4 to identify fetal cells.

RESULTS

Fifteen women in the first trimester and 15 women in the mid-trimester of pregnancy carried male fetuses. The rates of positive cells were 1:6528.0 and 1:2783.8 respectively, and there was a highly significant difference when these rates were compared with the positive cells rate of the 10 female fetuses in the same trimesters. No significant difference in positive cells rate was found between 1 week after delivery and the mid-trimester of pregnancy, nor was it found between 3 months after delivery and the 10 samples of female fetuses in the same time.

CONCLUSION

These data suggest that fetal cells can be detected as early as from 50 days of gestation in maternal blood, in the meantime, the rate of fetal cells will increase with gestational age. One week after delivery, fetal cells still exist, and 3 months after delivery, the fetal cells will no longer be detected.

[Multiple organ dysfunction syndrome after open chest wound and seawater immersion: experimental study]

OBJECTIVE

To evaluate the effect of seawater immersion on multiple organ dysfunction syndrome (MODS) after chest trauma.

METHODS

Twenty health dogs were divided into two groups. Right open pneumothorax was induced in both control group (n = 10) and experimental group (n = 10). After induction of chest trauma, animals in the experimental group were immersed in artificial seawater. Blood samples were taken at seven different intervals for assessing blood gas, plasma level of TNFalpha, and IL-1 beta. Changes of serum alanine aminotransferase (ALT), aspartate amino-transferase (AST), creatine kinase (CK) lactate dehydrogenase (LDH) and creatinine (Cr) were measured. At the end of study, lung was harvested for assessing lung water content and ratio of wet weight and dry weight.

RESULTS

A significant elevation of ALT, AST, CK and LDH was observed in both groups. Organ functional parameters in the experimental group were consistent with the failure standard at 30 minutes after seawater immersion, and those in the control group at 4 hours. Post-trauma mortality and incidence of MODS were much higher in the experimental group than those in the control group (P < 0.01). The plasma levels of TNFalpha and IL-1 beta significantly increased at 30 minutes and reached the highest level at 60 minutes after seawater immersion. The time of peak level appeared earlier in the experimental group than that in the control group.

CONCLUSION

Seawater immersion after open chest trauma results in high incidence of MODS and high mortality rate due to progressive dysfunction of multiple organs.

20-O-acylcamptothecin derivatives: evidence for lactone stabilization

Convincing UV and NMR spectrophotometric evidence is presented which demonstrates that at physiological pH, 7.4, 20-O-acyl derivatives of camptothecin (CPT) are substantially more stable in the lactone form than the 20-OH parent. Additionally, it was determined by HPLC analysis that the lactone ring of a 20-O-ether derivative of CPT underwent endocyclic ring opening at pH > or =8.5, while the lactone ring of 20-O-acyl CPT derivatives remained unaffected. PEG (and other smaller alkyl) 20-O-acyl-CPT derivatives released native CPT at pH > 9.5, which arises from exocyclic cleavage, thus precluding isolation of any open CPT acyl PEG (or alkyl) carboxylate forms.

[Experimental study on anti-fatigue effect of shenfu injection on diaphragmatic muscle]

OBJECTIVE

To study the effect of Shenfu injection (SFI) on function of diaphragmatic muscle in rabbits.

METHODS

Taking the transdiaphragmatic pressure (Pdi), diaphragmatic electromyogram (EMGdi) and diaphragmatic evoked potential (DEP) as criteria for observation, the diaphragmatic fatigue (DiF) was induced by stimulating bilateral phrenic nerve for 30 minutes. Pdi, EMGdi and DEP induced by stimulation with different frequency (Fc) were recorded before and after treatment. Then the high/low (H/L) frequency ratio and central Fc were calculated and analysed by variance analysis and q test.

RESULTS

After administration of 2 ml/kg of SFI, the Pdi, H/L, Fc and amplitude of DEP were markedly increased and latent phase of DEP was shortened by the drug, in comparing with those before treatment, P < 0.05.

CONCLUSION

SFI has the effect in antagonizing diaphragmatic fatigue.

[Allele-specific chromosome 3p deletion in primary non-small cell lung cancer.]

BACKGROUND

To investigate the relationship between loss of heterozygosity (LOH) of the allele genes on 3p and the pathogenesis of NSCLC.

METHODS

Using polymerase chain reaction-based assays for dinucleotide repeat polymorphisms to analyze allele loss of 3p in 162 NSCLC samples.

RESULTS

Of the 162 cases with NSCLC , 108 (66. 67 %) had LOH on 3p. Among them , 65 cases (40. 12 %) had LOH at 3p14 , 84 cases (51. 85 %) had LOH at 3p25 , and 41 cases (25. 31 %) occured co-deletion of 3p14 and 3p25. No 3p LOH were observed in 85 paracancerous lung tissues and 5 tissues of the pulmonary benign diseases. The total frequency of LOH at 3p did not relate to TNM staging and pathological classification in NSCLC ( P > 0. 05) . However , the co2deletion rate of 3p14 and 3p25 was significantly higher in adenocarcinoma (38 % , 19/ 50) than that in squamous cell carcinoma (19. 51 % ,16/82) ( P < 0. 05) . And 3p LOH rate in stage II(51. 28 % ,20/ 39) and stage III(44. 93 % ,31/ 69) were both remarkably higher than that of stage I(25. 93 % ,14/ 54) ( P < 0. 05) .

CONCLUSIONS

3p LOH occur commonly in human NSCLC. It suggests that each region harbor one or more tumor suppressor genes , the inactivation of which might be critical for the oncogenesis and development of lung cancer.

[Lateral approaches for treatment of petroclival region tumor]

OBJECTIVE

To summarize the operation experience of resecting petroclival region tumors by lateral approaches.

METHODS

(1) Ameliorate pterion approach; (2) temporal-occipital transtentorial-transpetrous approach; (3) transpetrous combined with supratentorial and infratentorial presigmoid approach; (4) far lateral transcondylar approach were applied for 61 patients with petroclival region tumor.

RESULTS

Of the 61 tumors studied, 54 were completely resected, 6 were nearly complete and 1 was subtotally resected. No patient died in this group, 37 patients were followed up, and all showed satisfying results. 45% of the patients had CNs deficit, with III, VI, V, VIII, IX, X, XII nerve deficits most commonly seen.

CONCLUSION

Lateral approaches are recommended for total resection of petroclival region tumors. HoVDever the operative techniques are complex and potential risks of morbidity exist.

Inhibition of Na-K-ATPase activity and gene expression by a myeloma light chain in proximal tubule cells

BACKGROUND

Light chain nephrotoxicity is frequently associated with Fanconi syndrome characterized by amino-aciduria, glycosuria, phosphaturia, and bicarbonaturia. The mechanisms of these transport abnormalities are unknown. To determine the role of Na-K-ATPase, we examined the effects of a lambda-light chain on both the activity and gene expression of Na-K-ATPase in primary cultures of rat proximal tubule cells.

METHODS

The lambda-light chain used here was isolated from urine of a patient with multiple myeloma and previously shown to inhibit sodium-dependent phosphate and glucose transport in proximal tubule cells. Na-K-ATPase was determined spectrophotometrically and the gene expression by Northern analysis in cells exposed to light chain.

RESULTS

In cells exposed to 200 mumol/L light chain Na-K-ATPase activity was reduced significantly, up to 73%, at 2, 24, and 48 hours compared with control cells (N = 12, P < 0.001). Northern analysis showed that in cells exposed to light chain for 24 and 48 hours the message for the alpha-1 isoform of Na-K-ATPase was suppressed significantly compared with control cells. The messages for GAPDH, beta-actin, and 28 S RNA in light chain exposed cells were also depressed in comparison with control cells. This light chain also significantly inhibited thymidine incorporation by proximal tubule cells in a dose-dependent manner.

CONCLUSIONS

These data suggest a general toxicity to cells by this light chain and indicate that inhibitory effects on both the activity and gene expression of Na-K-ATPase may be an important mechanism of light chain cytotoxicity on proximal tubule cells.

[Transpetrosal presigmoid approach for removal of giant petroclival tumors]

OBJECTIVE

To discuss the operative technique, advantage and postoperative complications in 41 patients with giant petroclival tumors treated with the supra- and infratentorial transpetrousal presigmoid approach.

METHODS

Clinical data were obtained from the review of charts and radiographic images of the 41 patients after operation with temporo-occipotal free osseous flap, partial petrosectomy and mastoidectomy were performed around the labyrinth. The semicircular canals, cochlea and tympanic cavity were protected during the operation. After the super petrous was ligated and cut off, the petroclival region in front of the sigmoid sinus was exposed.

RESULTS

In the 41 patients 20 had meningiomas, 20 epidermoid cysts, and one schwannoma. Total resection was performed in 34 patients, subtotal resection in 16, and greater partial resection in one. Major postoperative complications included temporal aphasia (10 patients), cerebral edema (6), brain stem infarct (2), IIIth, VIIth, VIth and posterial group cranial nerves palsies (16, 16, 8, 6 respectively), and cerebrospinal fluid leakage (4 cases).

CONCLUSIONS

This approach can expose sufficiently the petroclival region. It can also reveal the area of adjacent sella, interpeduncular and formen magnum, and homolateral III-XIIth cranial nerves. The postoperative complications may be related to operative techniues and tumorous characteristics.

Combinatorial discovery of oxidative dehydrogenation catalysts within the Mo-V-Nb-O system

Combinatorial methodologies were used for the synthesis and screening of mixed metal oxide heterogeneous catalysts. Primary screening at low reactant conversions at a throughput of greater than 10,000 catalyst compositions per month was performed by using simultaneous MS and photothermal deflection spectroscopy on spatially separated thick film catalysts with approximately 200 microg per catalyst prepared by using automated liquid dispensing. Secondary screening under realistic operating conditions was performed at a throughput of greater than 3,000 catalyst compositions per month on approximately 50 mg of catalyst in an array of fixed bed microreactors with gas chromatograph detection. The approach was validated by the discovery of catalysts with superior performance to those previously described for the oxidative dehydrogenation of ethane to ethylene. We show the full implementation and integration of combinatorial methodologies for synthesis, screening, discovery, and optimization of multicomponent heterogeneous catalysts.

Drug delivery of anticancer agents: water soluble 4-poly (ethylene glycol) derivatives of the lignan, podophyllotoxin

This paper reports on the synthesis and in vivo oncolytic activity of a series of water-soluble acyl derivatives of polyethylene glycol (PEG) conjugated podophyllotoxin. Some analogs of the polymer conjugate showed significantly better activity in a murine leukemia model than native podophyllotoxin suspended in an intralipid emulsion. Additionally, when tested intravenously against a solid lung tumor (A549) model, some conjugated analogs were equivalent to the podophyllotoxin/intralipid emulsion, while those compounds demonstrating slower rates of plasma hydrolysis (in vitro) appeared to cause greater toxicity. There appeared to be an overall correlation between the in vivo antitumor activity of the conjugate and its rate of hydrolysis in vitro, with those showing faster release possessing greater antitumor activity. In conclusion, the solubilization and predictable release of podophyllotoxin from a PEG carrier was achieved and resulted in some derivatives demonstrating, at a minimum, equivalency with podophyllotoxin when administered on an equal molar basis. Further studies may be warranted to assess the PEG-conjugates pharmacokinetics and therapeutic indices in leukemic models.

Drug delivery systems employing 1,4- or 1,6-elimination: poly(ethylene glycol) prodrugs of amine-containing compounds

A general methodology for synthesizing poly(ethylene glycol) (PEG) prodrugs of amino-containing compounds has been developed and constitutes the basis for solubilization of insoluble drugs, extending plasma circulating half-lives and, in the case of anticancer agents, apparent tumor accumulation. Thus, we have successfully designed PEG conjugated specifiers or "triggers" as part of a double-prodrug strategy that relies, first, on enzymatic separation of PEG followed by the classical and rapid 1,4- or 1, 6-benzyl elimination reaction releasing the amine (drug) bound in the form of a carbamate. The prodrug trigger was comprised of ester, carbonate, carbamate, or amide bonds in order to secure predictable rates of hydrolysis. Further refinement of the hydrolysis was accomplished by the introduction of steric hindrance through the use of ortho substituents on the benzyl component of the prodrug. This modification led to longer circulating plasma half-lives of the final tripartate form. The "ortho" effect also had the beneficial effect of directing nucleophilic attack almost exclusively to the activated benzyl 6-position of the heterobifunctional intermediates. In vivo testing of the PEG daunorubicin prodrugs (transport forms) prepared in the course of this study ultimately identified the type 1 carbamate (34b), with a circulating t(1/2) of 4 h, as the most effective derivative for solid tumor growth inhibition.

N-Glycosylation of pig flavin-containing monooxygenase form 1: determination of the site of protein modification by mass spectrometry

By using a combination of biochemical methods (i.e., endoglycosidase H digestion and immunoblot and plant lectin binding studies), it was verified that pig flavin-containing monooxygenase (FMO1) was N-glycosylated. By using mass spectrometry approaches [i.e., peptide mapping, gas chromatography/mass spectrometry, microbore HPLC/electrospray ionization mass spectrometry (LC/ESI/MS), chemical ionization gas chromatography/mass spectrometry (CI/GC/MS), and matrix-assisted laser desorption mass spectrometry (MALDI/MS)], we were able to confirm that pig FMO1 was N-glycosylated and we were able to identify the site of N-glycosylation. Pig FMO1 contains two putative consensus sites of N-glycosylation. The results showed that pig FMO1 amino acid Asn120 was selectively N-glycosylated. Highly purified pig FMO1 avidly bound concanavalin A and reacted positively for carbohydrates by the periodic acid/Schiff's base method of analysis. In addition, treatment of pig FMO1 with endo-N-acetylglucosaminidase converted the enzyme to another species with a molecular mass approximately 5000 Da lower than that of the parent protein as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot experiments. Peptide mapping of pig FMO1 showed that the protein used in the study was not contaminated with another glycoprotein. MALDI/MS experiments showed that pig FMO1 was present with the expected molecular mass but that higher-molecular mass forms consistent with the presence of N-linked high-mannose oligosaccharide structures were also covalently attached to the enzyme. The presence of N-acetylglucosamine isolated from acid hydrolysates of the N-linked high-mannose oligosaccharide of pig FMO1 was confirmed by high-pH anion exchange HPLC studies and verified by CI/GC/MS studies of derivatized monosaccharide fractions. Further analysis of pig FMO1 proteolytic peptides by LC/ESI/MS showed that the only residue that was N-glycosylated in pig FMO1 was Asn120. Knowledge of the structural aspects of FMO may be useful in understanding the membrane association properties of the enzyme.

Serotype conversion of a Shigella flexneri candidate vaccine strain via a novel site-specific chromosome-integration system

Shigella flexneri SFL124 (serotype Y) is a promising live oral vaccine candidate, which has been shown to be safe and immunogenic in human volunteers. To change the serotype of this vaccine strain, we inserted a serotype conversion gene cluster into the chromosome of SFL124 by using a bacteriophage-based site-specific integration system. By cloning an integrase gene (int), an attachment site (attP) and a glucosyl transfer gene cluster from bacteriophage SfX into a suicide vector, and subsequently introducing this construct into S. flexneri SFL124, we obtained a S. flexneri strain (designated SFL1213) expressing the serotype X somatic antigen specificity. The strain retained other characteristics of the parent strain, such as colony shape, growth rate, and Congo red binding property. Stability test showed that the serotype X O-antigen specificity in SFL1213 was 100% stable after being cultured approximately 72 successive hours under non-selective condition. In a mouse pulmonary model, the recombinant strain elicited a significant level of humoral antibodies which recognized the lipopolysaccharide (LPS) of a wild-type S. flexneri serotype X strain. The site-specific insertion system will be useful when stable expression of a cloned single copy gene is desired in the chromosome of S. flexneri vaccine candidate, SFL124.

[Allele-specific chromosome 3p25 deletion detected by PCR-LOH analysis in non-small cell lung cancer.]

BACKGROUND

To ascertain whether the loss of heterozygosity (LOH) of allele on chromosome 3p25 region is associated with non-small cell lung cancer (NSCLC) .

METHODS

3p25 LOH was analysed in patients with NSCLC by polymerase chain reaction-based assays for dinucleatide repeat polymorphisms.

RESULTS

Eighty out of 158 (50. 6 %) cancer tissues of NSCLC were found to have 3p25 LOH , but no 3p25 LOH was observed in 5 normal fetal lung tissues and 4 tissues of the benign lung neoplasms. The deletion was detected in 62.0% of adenocarcinoma and 43.2% of the squamous carcinoma , indicating that the former was significantly higher than the latter ( P < 0. 05) . Loss frequences for TNM stages were further observed in 52.2% , 45.0% and 52.8% of the cases for stage I, II and III respectively , and these data showed no significant relationship between the loss frequence and TNM staging of NSCLC ( P > 0. 05) .

CONCLUSIONS

Above findings display that 3p25 LOH appear to be a common structural alteration occurred in NSCLC and there may be suppressor genes relevant to the carcinogenesis of the lung in 3p25 region.

Electrospray ionization and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry of permethylated oligosaccharides

Mass spectra of fragments of permethylated oligosaccharides are analyzed by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Sustained off-resonance irradiation (SORI) collision-induced dissociation (CID), quadrupolar axialization, multiple stages of isolation and dissociation (MSn), and ion remeasurement are exploited for carbohydrate structural analyses. That SORI CID internal energies are adequate for linkage analysis of a permethylated glucose oligomer is demonstrated by identifying ring-opened fragment ions from MALDI-generated mass-isolated and collisionally activated ions. Ion remeasurement and axialization techniques enhance the sensitivity of ion fragmentation analysis. Multiple stages of isolation and dissociation of ion fragments (MSn) provide for structural analysis of an electrospray-ionized permethylated lacto-N-fucopentaose isomer (LNFP II). Compared to MS2 spectra taken with a triple quadrupole, FT-ICR MSn (n > 2) provides more extensive characterization of the parent molecular structure than is available from a single stage of ion isolation and dissociation (MS2).

A discussion about the DiFrancesco-Noble model

An obvious defect in the DiFrancesco-Noble (DN) model was found, so methods to overcome this inadequacy are put forward. Based on these methods, different kinds of modified DN model can be obtained, and numerical results show that most of the dynamics of the DN model can be essentially preserved by these modified systems.

Receptor-mediated endocytosis of immunoglobulin light chains by renal proximal tubule cells

We examined the binding, endocytosis, and degradation of immunoglobulin light chains by primary cultures from rat renal kidneys and immortalized human proximal tubule cells. Both the association and dissociation of light chain were rapid and plateaued within 30 min at 4 degrees C. Up to 10(-3) M bovine serum albumin did not inhibit light chain binding to cells. Internalization studies with 125I-labeled kappa- and lambda-light chains by cells using the acid wash technique showed that up to 80% of total cell-associated binding at equilibrium (30 min) is rapidly internalized at 22 degrees C. Comparison of binding and internalization of light chains with transferrin, a ligand known to undergo receptor-mediated endocytosis, showed that both ligands displayed saturable kinetics. In contrast, endocytosis of sucrose, a marker for fluid-phase endocytosis, was unsaturable and nearly 200-fold less efficient than light chain internalization. Scatchard analysis of binding experiments done at 4 degrees C with trace 125I-labeled lambda-light chain in presence of 0 to 3.0 x 10(-3) M cold light chain revealed a single class of binding sites with a dissociation constant of 5.0 +/- 0.8 x 10(-5) and a maximal binding capacity of 1.6 +/- 0.3 x 10(-9) mol/mg cell protein. Hypertonic medium, a maneuver which interferes with the formation of the clathrin lattice, reduced endocytosis of light chain significantly but did not affect endocytosis of sucrose. Chloroquine and bafilomycin A, agents that interfere with vesicular acidification, also significantly suppressed light chain endocytosis. Using acid precipitation method, we observed that endocytosis of 125I-labeled lambda-light chain results in degradation by the rat renal proximal tubule cells. Degradation was maximum at 37 degrees C, significantly reduced at 22 degrees C, and absent at 4 degrees C. Excess light chain inhibited degradation of radiolabel, whereas excess albumin had no effect. These studies document the presence of binding sites for light chains on proximal tubule cells that mediate endocytosis of light chains by proximal tubule cells. The present data suggest that receptor-mediated endocytosis of light chains leads to delivery of this ligand to degradative sites through acidified vesicles.

Linear prediction Cholesky decomposition vs Fourier transform spectral analysis for ion cyclotron resonance mass spectrometry

The fast Fourier transform (FFT) method of spectral analysis converts a time domain signal to a more easily visualized frequency domain spectrum but does not distinguish between signal and noise and produces spectral artifacts (e.g., "Gibb's oscillations") for a truncated and/or improperly sampled time domain signal. For example, FFT cannot resolve two signals if the sampling duration is less than one cycle of the frequency difference between the two signals. Here, linear prediction Cholesky decomposition spectral analysis is applied to ion cyclotron resonance mass spectrometry. The algorithm is robust and capable of extracting spectral parameters (frequency, time domain exponential damping constant, magnitude, and phase) from a signal consisting of multiple exponentially damped noisy sinusoids. Compared to FFT data reduction, linear prediction can offer significantly increased sensitivity (for signals at or below the rms noise level), elimination of Gibb's oscillations, and increased spectral resolving power for a time domain signal that either is truncated or has damped to the rms noise level before the end of the acquisition period. The present analysis can handle up to 8K time domain data sets with 2.5 h PC computation time.

Detection, number, and sequence location of sulfur-containing amino acids and disulfide bridges in peptides by ultrahigh-resolution MALDI FTICR mass spectrometry

Here, we present several strategies for determining the number of sulfur atoms and disulfide bridges in selected biologically active peptides, based on MALDI FTICR mass spectrometry at femtomole sample consumption level. First, based on the 2-Da mass increase per disulfide bridge reduction, we show that repeated laser shots on the same sample spot can reduce (and therefore reveal the presence of) the disulfide bridge in oxytocin. Second, we show that the primary sequence positions of the disulfide-bridged cystines can be inferred from the presence/absence of MALDI-induced reduction in cystine-containing fragment ions. Third, we show that the presence and number of sulfur atoms as well as the degree of reduction in a peptide can all be determined directly from isotopic relative abundances of mass-resolved 34S, 13C2, and reduced all-12C species in a single ultrahigh-resolution MALDI FTICR mass spectrum. Methods for achieving such ultrahigh mass resolution of peptide ions of closely spaced m/z (m/delta m50% approximately 950,000 at m/z approximately 650) at modest magnetic field (3 T) are discussed.

Two-way conversation with a mass spectrometer: nondestructive interactive mass spectrometry

Most mass spectrometers employ destructive detection, so that it is necessary to repeat an experiment in order to vary even one parameter. In contrast, Fourier transform ion cyclotron resonance mass spectrometry offers nondestructive detection, so that ions remain available for further manipulation and redetection. Here, we show for the first time how to perform mass spectrometry interactively. Following each elementary experimental stage, such as ion generation, isolation, dissociation, or detection, the operator is free to choose and tailor the next stage without creating a fresh supply of ions. For example, we can test the effect of varying one parameter over several values without having to repeat the entire experimental event sequence each time, much like varying one letter or word in a sentence without having to rewrite the whole sentence. Such interactive control promises to speed development of complex experimental event sequences, as for optimizing the sequencing and structural analysis of tiny amounts (e.g., femtomoles or less) of biomacromolecules (peptides, nucleic acids, oligosaccharides).

High-resolution multistage MS, MS2, and MS3 matrix-assisted laser desorption/ionization FT-ICR mass spectra of peptides from a single laser shot

By combined and repeated use of sustained off-resonance irradiation (SORI) for ion dissociation, stored waveform inverse Fourier transform (SWIFT) waveforms for ion isolation, and ion axialization and remeasurements techniques, we obtain for the first time MS, MS2, and MS3 FT-ICR mass spectra from peptide ions (enzymatic digest products of horse cytochrome c) produced from a single laser shot. The successive fragmentation of gas-phase ions detected from the same initial batch of ions increases the sensitivity of analysis of trace amounts of biological samples in structural mass spectrometry, and fragment identification is facilitated by resolution of carbon-13 isotopic distributions. The method is illustrated by analyses of subfemtomole amounts of crudely purified samples of tryptic digest solutions of horse cytochrome c and bovine cytochrome c. The high-resolution primary ion mass spectrum, along with the collision-induced dissociation (CID) and MSn capabilities of FT-ICR, help to determine the primary amino acid sequence of the fragment ions beyond what is obtained from enzymatic digestion alone, without prior chromatographic separation and purification.

Determination of ion magnetron radial distribution in Fourier transform ion cyclotron resonance mass spectrometry

The spatial distribution of the ion cyclotron orbit 'guiding centers' (magnetron radii) in a Penning trap determines virtually all aspects of Fourier transform ion cyclotron resonance (FTICR) mass spectrometry performance. Here, we demonstrate experimentally a simple method for determining that distribution, based on measuring FTICR mass spectral peak height following dipolar excitation/dipolar detection at various stages of magnetron radial expansion. No instrumental modifications are needed. Such data will make it possible to evaluate theoretical models of space charge and to quantitate and optimize ion formation, ion injection, ion trapping, ion transfer, photodissociation and ultrahigh-resolution FTICR experiments.

Fourier transform ion cyclotron resonance mass spectrometry in a 20 T resistive magnet

We present Fourier transform ion cyclotron resonance (FTICR) mass spectra at a magnetic field of 20 T; more than twice the highest field previously used for FTICR. Our instrument is based on a resistive magnet installed at the National High Magnetic Field Laboratory. The magnet has a 50 mm diameter bore and spatial inhomogeneity of approximately 1000 ppm over a 1 cm diameter spherical volume. However, FTICR mass resolving power far in excess of magnet homogeneity is achieved routinely for ions produced by either electron ionization (EI) or matrix-assisted laser desorption/ionization (MALDI). As examples, we show a MALDI mass spectrum of [M + H] quasimolecular ions of the peptide, human luteinizing hormone-releasing hormone (monoisotopic molecular weight, 1181.6 Da) at mass resolving power, m/delta m > 10,000; and an EI mass spectrum of molecular ions of the platinum cluster compound, Pt4(PF3)8 (average molecular weight, 1484 Da at mass resolving power, m/delta m approximately 20,000. Much better FTICR MS performance is predicted for future NHMFL resistive magnets of higher spatial and temporal homogeneity.