The importance of the timing of microbial signals for perinatal immune system development

Background: Development and maturation of the immune system begin in utero and continue throughout the neonatal period. Both the maternal and neonatal gut microbiome influence immune development, but the relative importance of the prenatal and postnatal periods is unclear. Methods: In the present study, we characterized immune cell populations in mice in which the timing of microbiome colonization was strictly controlled using gnotobiotic methodology. Results: Compared to conventional (CONV) mice, germ-free (GF) mice conventionalized at birth (EC mice) showed few differences in immune cell populations in adulthood, explaining only 2.36% of the variation in immune phenotypes. In contrast, delaying conventionalization to the fourth week of life (DC mice) affected seven splenic immune cell populations in adulthood, including dendritic cells and regulatory T cells (Tregs), explaining 29.01% of the variation in immune phenotypes. Early life treatment of DC mice with Limosilactobacillus reuteri restored splenic dendritic cells and Tregs to levels observed in EC mice, and there were strain-specific effects on splenic CD4+ T cells, CD8+ T cells, and CD11c+ F4/80+ mononuclear phagocytes. Conclusion: This work demonstrates that the early postnatal period, compared to the prenatal period, is relatively more important for microbial signals to influence immune development in mice. Our findings further show that targeted microbial treatments in early life can redress adverse effects on immune development caused by the delayed acquisition of the neonatal gut microbiome.

A phylogenomic analysis of Limosilactobacillus reuteri reveals ancient and stable evolutionary relationships with rodents and birds and zoonotic transmission to humans

BACKGROUND

Gut microbes play crucial roles in the development and health of their animal hosts. However, the evolutionary relationships of gut microbes with vertebrate hosts, and the consequences that arise for the ecology and lifestyle of the microbes are still insufficiently understood. Specifically, the mechanisms by which strain-level diversity evolved, the degree by which lineages remain stably associated with hosts, and how their evolutionary history influences their ecological performance remain a critical gap in our understanding of vertebrate-microbe symbiosis.

RESULTS

This study presents the characterization of an extended collection of strains of Limosilactobacillus reuteri and closely related species from a wide variety of hosts by phylogenomic and comparative genomic analyses combined with colonization experiments in mice to gain insight into the long-term evolutionary relationship of a bacterial symbiont with vertebrates. The phylogenetic analysis of L. reuteri revealed early-branching lineages that primarily consist of isolates from rodents (four lineages) and birds (one lineage), while lineages dominated by strains from herbivores, humans, pigs, and primates arose more recently and were less host specific. Strains from rodent lineages, despite their phylogenetic divergence, showed tight clustering in gene-content-based analyses. These L. reuteri strains but not those ones from non-rodent lineages efficiently colonize the forestomach epithelium of germ-free mice. The findings support a long-term evolutionary relationships of L. reuteri lineages with rodents and a stable host switch to birds. Associations of L. reuteri with other host species are likely more dynamic and transient. Interestingly, human isolates of L. reuteri cluster phylogenetically closely with strains from domesticated animals, such as chickens and herbivores, suggesting zoonotic transmissions.

CONCLUSIONS

Overall, this study demonstrates that the evolutionary relationship of a vertebrate gut symbiont can be stable in particular hosts over time scales that allow major adaptations and specialization, but also emphasizes the diversity of symbiont lifestyles even within a single bacterial species. For L. reuteri, symbiont lifestyles ranged from autochthonous, likely based on vertical transmission and stably aligned to rodents and birds over evolutionary time, to allochthonous possibly reliant on zoonotic transmission in humans. Such information contributes to our ability to use these microbes in microbial-based therapeutics.

A secondary metabolite drives intraspecies antagonism in a gut symbiont that is inhibited by cell-wall acetylation

The mammalian microbiome encodes numerous secondary metabolite biosynthetic gene clusters; yet, their role in microbe-microbe interactions is unclear. Here, we characterized two polyketide synthase gene clusters (fun and pks) in the gut symbiont Limosilactobacillus reuteri. The pks, but not the fun, cluster encodes antimicrobial activity. Forty-one of 51 L. reuteri strains tested are sensitive to Pks products; this finding was independent of strains' host origin. Sensitivity to Pks was also established in intraspecies competition experiments in gnotobiotic mice. Comparative genome analyses between Pks-resistant and -sensitive strains identified an acyltransferase gene (act) unique to Pks-resistant strains. Subsequent cell-wall analysis of wild-type and act mutant strains showed that Act acetylates cell-wall components, providing resistance to Pks-mediated killing. Additionally, pks mutants lost their competitive advantage, while act mutants lost their Pks resistance in in vivo competition assays. These findings provide insight into how closely related gut symbionts can compete and co-exist in the gastrointestinal tract.

Limosilactobacillus balticus sp. nov., Limosilactobacillus agrestis sp. nov., Limosilactobacillus albertensis sp. nov., Limosilactobacillus rudii sp. nov. and Limosilactobacillus fastidiosus sp. nov., five novel Limosilactobacillus species isolated from the vertebrate gastrointestinal tract, and proposal of six subspecies of Limosilactobacillus reuteri adapted to the gastrointestinal tract of specific vertebrate hosts

Ten strains, BG-AF3-AT, pH52_RY, WF-MT5-AT, BG-MG3-A, Lr3000T, RRLNB_1_1, STM3_1T, STM2_1, WF-MO7-1T and WF-MA3-C, were isolated from intestinal or faecal samples of rodents, pheasant and primate. 16S rRNA gene analysis identified them as Limosilactobacillus reuteri. However, average nucleotide identity and digital DNA-DNA hybridization values based on whole genomes were below 95 and 70 %, respectively, and thus below the threshold levels for bacterial species delineation. Based on genomic, chemotaxonomic and morphological analyses, we propose five novel species with the names Limosilactobacillus balticus sp. nov. (type strain BG-AF3-AT=DSM 110574T=LMG 31633T), Limosilactobacillus agrestis sp. nov. (type strain WF-MT5-AT=DSM 110569T=LMG 31629T), Limosilactobacillus albertensis sp. nov. (type strain Lr3000T=DSM 110573T=LMG 31632T), Limosilactobacillus rudii sp. nov. (type strain STM3_1T=DSM 110572T=LMG 31631T) and Limosilactobacillus fastidiosus sp. nov. (type strain WF-MO7-1T=DSM 110576T=LMG 31630T). Core genome phylogeny and experimental evidence of host adaptation of strains of L. reuteri further provide a strong rationale to consider a number of distinct lineages within this species as subspecies. Here we propose six subspecies of L. reuteri: L. reuteri subsp. kinnaridis subsp. nov. (type strain AP3T=DSM 110703T=LMG 31724T), L. reuteri subsp. porcinus subsp. nov. (type strain 3c6T=DSM 110571T=LMG 31635T), L. reuteri subsp. murium subsp. nov. (type strain lpuph1T=DSM 110570T=LMG 31634T), L. reuteri subsp. reuteri subsp. nov. (type strain F 275T=DSM 20016T=ATCC 23272T), L. reuteri subsp. suis subsp. nov. (type strain 1063T=ATCC 53608T=LMG 31752T) and L. reuteri subsp. rodentium subsp. nov. (type strain 100-23T=DSM 17509T=CIP 109821T).

A Phylogenetic View on the Role of Glycerol for Growth Enhancement and Reuterin Formation in Limosilactobacillus reuteri

Lineages within the species Limosilactobacillus reuteri have specialized to various hosts and their genomes reflect these adaptations. The pdu-cbi-cob-hem gene cluster is conserved in most human and poultry isolates but is infrequent in rodent and porcine isolates. This gene cluster confers the transformation of glycerol into 3-hydroxy-propionaldehyde (reuterin), which can either be secreted and function as precursor of the antimicrobial compound acrolein or serve as an electron acceptor that enhances the organisms’ growth rate. However, it remains unclear which of these two functions is more relevant for L. reuteri evolution and ecology. Here we characterized the effect of glycerol on growth rate and reuterin formation in L. reuteri strains across different phylogenetic lineages during growth on ecologically relevant carbohydrates. We further evaluated the innate reuterin resistance among these strains to infer a possible role of reuterin in the evolution of strains. Results revealed that the poultry/human lineage VI strain, L. reuteri DSM 17938 shows more growth enhancement through glycerol and greater capacity for reuterin production on glucose and maltose as compared to human lineage II strains. Interestingly, reuterin production in lineage II strains was significantly elevated on raffinose and lactose, reaching levels similar to DSM 17938. On all carbohydrates tested, reuterin production occurred during the exponential growth phase and became undetectable during the stationary growth phase. The amount of reuterin produced was sufficient to inhibit E. coli, suggesting that it could be ecologically relevant, but the resistance towards reuterin among L. reuteri strains was highly variable and, for the most part, unrelated to the strain’s capacity for reuterin production. Overall, the findings suggest differences in the substrate-specific regulation of the pdu cluster in L. reuteri lineages that might be reflective of their ecological niches, e.g., chicken foregut versus human infant and adult large intestine. Such information can inform future studies on the ecology of L. reuteri and guide the development of synbiotic applications to improve the therapeutic use of this species.

Ecological Importance of Cross-Feeding of the Intermediate Metabolite 1,2-Propanediol between Bacterial Gut Symbionts

Cross-feeding based on the metabolite 1,2-propanediol has been proposed to have an important role in the establishment of trophic interactions among gut symbionts, but its ecological importance has not been empirically established. Here, we show that in vitro growth of Lactobacillus reuteri (syn. Limosilactobacillus reuteri) ATCC PTA 6475 is enhanced through 1,2-propanediol produced by Bifidobacterium breve UCC2003 and Escherichia coli MG1655 from the metabolization of fucose and rhamnose, respectively. Work with isogenic mutants showed that the trophic interaction is dependent on the pduCDE operon in L. reuteri, which encodes the ability to use 1,2-propanediol, and the l-fucose permease (fucP) gene in B. breve, which is required for 1,2-propanediol formation from fucose. Experiments in gnotobiotic mice revealed that, although the pduCDE operon bestows a fitness burden on L. reuteri ATCC PTA 6475 in the mouse digestive tract, the ecological performance of the strain was enhanced in the presence of B. breve UCC2003 and the mucus-degrading species Bifidobacterium bifidum The use of the respective pduCDE and fucP mutants of L. reuteri and B. breve in the mouse experiments indicated that the trophic interaction was specifically based on 1,2-propanediol. Overall, our work established the ecological importance of cross-feeding relationships based on 1,2-propanediol for the fitness of a bacterial symbiont in the vertebrate gut.IMPORTANCE Through experiments in gnotobiotic mice that employed isogenic mutants of bacterial strains that produce (Bifidobacterium breve) and utilize (Lactobacillus reuteri) 1,2-propanediol, this study provides mechanistic insight into the ecological ramifications of a trophic interaction between gut symbionts. The findings improve our understanding on how cross-feeding influences the competitive fitness of L. reuteri in the vertebrate gut and revealed a putative selective force that shaped the evolution of the species. The findings are relevant since they provide a basis to design rational microbial-based strategies to modulate gut ecosystems, which could employ mixtures of bacterial strains that establish trophic interactions or a personalized approach based on the ability of a resident microbiota to provide resources for the incoming microbe.

Precision Microbiome Modulation with Discrete Dietary Fiber Structures Directs Short-Chain Fatty Acid Production

Dietary fibers (DFs) impact the gut microbiome in ways often considered beneficial. However, it is unknown if precise and predictable manipulations of the gut microbiota, and especially its metabolic activity, can be achieved through DFs with discrete chemical structures. Using a dose-response trial with three type-IV resistant starches (RS4s) in healthy humans, we found that crystalline and phosphate cross-linked starch structures induce divergent and highly specific effects on microbiome composition that are linked to directed shifts in the output of either propionate or butyrate. The dominant RS4-induced effects were remarkably consistent within treatment groups, dose-dependent plateauing at 35 g/day, and can be explained by substrate-specific binding and utilization of the RS4s by bacterial taxa with different pathways for starch metabolism. Overall, these findings support the potential of using discrete DF structures to achieve targeted manipulations of the gut microbiome and its metabolic functions relevant to health.

Toll-like receptor signalling associated with immunomodulation of umbilical cord-derived mesenchymal stem cells in mice with systemic lupus erythematosus

With potent immunomodulatory activities, mesenchymal stem cells (MSCs) have the potential to be a beneficial treatment option for diseases with aberrant immune responses such as systemic lupus erythematosus (SLE). However, the underlying mechanisms remain largely unknown. Here, we used NZBWF1 mice as a SLE animal model to examine immunomodulation of MSCs as well as to assess the role of Toll-like receptor signalling in this circumstance. We found that mice receiving MSCs had a significant decrease in severity of proteinuria at 20 and 22 weeks of age (p = 0.009 and p = 0.022, respectively). Serum anti-dsDNA levels were significantly lower compared with the control group (p = 0.016 and p = 0.036, respectively). C3 and C4 levels were significantly higher at 22 weeks of age (p = 0.046 and p = 0.016, respectively). Altered expression of inflammation-associated cytokine profiles in the serum was also noted in mice receiving MSCs. Down-regulation of myeloid differentiation factor 88 (MyD88)-nuclear factor-κB (NF-κB) signalling in the liver was demonstrated by quantitative polymerase chain reaction, ELISA and Western blotting. In addition to demonstrating the beneficial effects of MSC treatment in NZBWF1 mice, our study provided the first evidence for the association of MyD88-NF-κB signalling and MSC-mediated immunomodulation in this disease.

Ciguatera fish Poisoning: a Challenge to Emergency Physicians

Seven patients from two families presented with ciguatera poisoning after fish consumption. They suffered most of the typical clinical features of ciguatera poisoning and were given supportive treatments. Three of them were given mannitol infusion and showed improvement in symptoms. All of them were discharged within two days.

A 6-Year Epidemiological Study of Pulmonary Embolism in an Emergency Department

Objective

To identify the epidemiology and early clinical features of patients with pulmonary embolism with a view to facilitate making the correct diagnosis.

Methodology

A retrospective study of patients admitted through the emergency department with a discharge diagnosis of pulmonary embolism in the computerised Clinical Management System from 1st January 1999 to 31st December 2004 in a public emergency general hospital in Hong Kong.

Results

Twenty-two patients were newly diagnosed to have pulmonary embolism and included in the study. The patients' clinical features and investigation findings were analysed. Old age and immobilisation were the most common risk factors identified. Nine patients were found to have deep vein thrombosis but none of them complained of calf pain during consultation in the emergency department. Most patients had symptoms of shortness of breath and chest pain on presentation. Fourteen patients had type 1 respiratory failure. The electrocardiogram and chest X-ray findings were non-specific. All the patients with D-dimer done showed positive results. CT scans were used in all patients to make the final diagnosis. Nineteen patients received low molecular weight heparin followed by warfarin and three patients had thrombolytic therapy.

Conclusion

Pulmonary embolism is not a commonly diagnosed disease in Hong Kong. The symptoms are non-specific and it is difficult to make the correct diagnosis in the emergency department.

Empirical Selection of Informative Microsatellite Markers within Co-ancestry Pig Populations Is Required for Improving the Individual Assignment Efficiency

The Lanyu is a miniature pig breed indigenous to Lanyu Island, Taiwan. It is distantly related to Asian and European pig breeds. It has been inbred to generate two breeds and crossed with Landrace and Duroc to produce two hybrids for laboratory use. Selecting sets of informative genetic markers to track the genetic qualities of laboratory animals and stud stock is an important function of genetic databases. For more than two decades, Lanyu derived breeds of common ancestry and crossbreeds have been used to examine the effectiveness of genetic marker selection and optimal approaches for individual assignment. In this paper, these pigs and the following breeds: Berkshire, Duroc, Landrace and Yorkshire, Meishan and Taoyuan, TLRI Black Pig No. 1, and Kaohsiung Animal Propagation Station Black pig are studied to build a genetic reference database. Nineteen microsatellite markers (loci) provide information on genetic variation and differentiation among studied breeds. High differentiation index (FST) and Cavalli-Sforza chord distances give genetic differentiation among breeds, including Lanyu's inbred populations. Inbreeding values (FIS) show that Lanyu and its derived inbred breeds have significant loss of heterozygosity. Individual assignment testing of 352 animals was done with different numbers of microsatellite markers in this study. The testing assigned 99% of the animals successfully into their correct reference populations based on 9 to 14 markers ranking D-scores, allelic number, expected heterozygosity (HE) or FST, respectively. All miss-assigned individuals came from close lineage Lanyu breeds. To improve individual assignment among close lineage breeds, microsatellite markers selected from Lanyu populations with high polymorphic, heterozygosity, FST and D-scores were used. Only 6 to 8 markers ranking HE, FST or allelic number were required to obtain 99% assignment accuracy. This result suggests empirical examination of assignment-error rates is required if discernible levels of co-ancestry exist. In the reference group, optimum assignment accuracy was achievable achieved through a combination of different markers by ranking the heterozygosity, FST and allelic number of close lineage populations.

Estimations of fiber Bragg grating parameters and strain gauge factor using optical spectrum and strain distribution information

An inverse approach based on an optimization technique is proposed to characterize a fiber Bragg grating (FBG) and the strain gauge factor (GF) when the FBG is bonded on a structure. By bonding an FBG on a substrate and simply straining this FBG into a chirped fiber Bragg grating with a predesignated strain, the proposed method, based on an optimization technique, can be used to reconstruct seven parameters of the FBG from the corresponding reflective spectrum. The parameters identified are the length of an FBG, the grating period, the average refractive index, the index modulation, the apodization coefficient, the starting point bonded on the plate, and the strain GF. The information from the predesignated strain, as well as the measured reflective spectrum, is used as the objective function during the optimal search. As a result, the design sensitivity for the optimal search is much improved compared with the design sensitivity when only the reflective spectrum is used. In particular, the strain GF, which depends on the adhesive, the bonding layer characteristics, etc., can be determined in order to provide a reference for an FBG used as a strain sensor. Results from numerical simulations and experiments show that seven parameters of an FBG can be obtained accurately and efficiently.

Iatrogenic esophagobronchial fistula arising in irradiated Barrett's esophagus

A 47-yr-old male underwent a right upper lobectomy for stage IIB bronchoalveolar carcinoma followed by 4600 Gy of irradiation. One year later a fistula formed from an ulcerated region of Barrett's esophagus into the left main bronchus. Bronchotomy repair with onlay patch intercostal muscle flap and esophageal repair with serratus anterior muscle flap plus postoperative esophageal stent placement for stricture resulted in good functional results.

Design of antineoplastic agents based on the '2-phenylnaphthalene-type' structural pattern--synthesis and biological activity studies of 11H-indolo[3.2-c]quinoline derivatives

Designed as a new group of planar molecule containing the proposed 2-phenylnaphthalene-type structure, a number of 11H-indolo[3.2-c]quinoline derivatives were synthesized and evaluated biologically. Several compounds were found to possess cytotoxic activity against the growth of human promyelocytic leukemia cells (HL-60), against the small cell lung cancer (SCLC), and showed good response in the National Cancer Institute preclinical antitumor drug discovery 60-cell line panel.

Generation of electromagnetic pulses from plasma channels induced by femtosecond light strings

We present a model that elucidates the physics underlying the generation of an electromagnetic pulse from a femtosecond laser induced plasma channel. The radiation pressure force from the laser pulse spatially separates the ionized electrons from the heavier ions and the induced dipole moment subsequently oscillates at the plasma frequency and radiates an electromagnetic pulse.

CAPD-associated peritonitis caused by Alcaligenes xylosoxidans sp. xylosoxidans

Alcaligenes xylosoxidans is an uncommon cause of peritonitis in patients on maintenance continuous ambulatory peritoneal dialysis (CAPD). Peritonitis caused by A. xylosoxidans usually carries a poor prognosis because of the pathogen's virulence and its universal resistance to most antimicrobial agents. Even after early Tenckhoff catheter removal, the transport property of the peritoneum is often irreversibly damaged, leading to permanent technique failure. We report 2 patients with CAPD-associated peritonitis due to A. xylosoxidans sp. xylosoxidans who were successfully cured with a combination of piperacillin and tazobactam. One of them subsequently returned uneventfully to CAPD.

Long-term follow-up of interferon alfa treatment in Chinese patients with chronic hepatitis B infection: The effect on hepatitis B e antigen seroconversion and the development of cirrhosis-related complications

The long-term effect of interferon alfa (IFN-alpha) in Chinese patients with chronic hepatitis B infection is unknown. A total of 411 chronic hepatitis B patients (208 treated with IFN-alpha and 203 as control) were followed up for hepatitis B serology and the development of hepatoma and other cirrhosis-related complications. The hepatitis B e antigen (HBeAg) seroconversion rate in the IFN-alpha-treated group, though significantly greater at 6 and 24 months, was comparable with the control group on subsequent follow-up, irrespective of pretreatment alanine transaminase (ALT) levels. HBeAg seroreversion rate was higher in the IFN-alpha group compared with the control group (21.1% vs. 2.2%; P =.001). Loss of hepatitis B surface antigen (HBsAg) occurred in 2.4% of the IFN-alpha-treated patients and 0.49% of the control patients (P = NS). Around 90% of the anti-HBe-positive patients in both groups were still hepatitis B virus (HBV)-DNA-positive by polymerase chain reaction (PCR) assay. Two patients suffered from hepatic reactivation during the course of treatment. Nine (4.3%) patients in the IFN-alpha group and 2 (1.0%) in the control group developed complications of cirrhosis and hepatoma (P =.062). In Chinese HBsAg carriers, IFN-alpha was of no long-term benefit in inducing HBeAg seroconversion or in the prevention of hepatoma and other cirrhosis-related complications.

Poly(2-hydroxyethyl methacrylate) film as a drug delivery system for pilocarpine

This work investigates pilocarpine trapped in a matrix diffusion-controlled drug delivery system using hydrophilic inserts of Poly(2-hydroxyethyl methacrylate) (pHEMA) to ensure an increased bioavailability of pilocarpine and prolong the length of time in which the medication remains in the eyes of the test subjects. The physical and chemical properties of pilocarpine were investigated to elucidate the mechanism of drug-polymer interaction and the effect on drug release behavior of controlled release polymeric devices. In vitro release studies indicated that pilocarpine continued to be released from the inserts for a 24 h period. The results of intraocular pressure tests performed on albino rabbits were consistent with the observed in vitro behavior. The pressure decrease was significant for a period longer than 48 h. It confirms that the inserts, as sustainable releasing devices, are promising carriers for ophthalmic drug delivery systems.

Proteolysis of integrin α5 and β1 subunits involved in retinoic acid-induced apoptosis in human hepatoma Hep3B cells

Our previous report demonstrated that all-trans-retinoic acid (ATRA) induces detachment and death under serum starvation in several human tumor cell lines. In this study, we examined the influence of cell-extracellular matrix interaction on the ability of ATRA to induce apoptosis. Plating of human hepatoma Hep3B cells onto poly-hydroxyethylmethacrylate-coated plates in the absence of serum resulted in the acceleration of ATRA-induced apoptosis. In contrast, ATRA-induced apoptosis was significantly suppressed by plating cells onto Matrigel-coated plates but not suppressed by culturing onto collagen-, laminin-, vitronectin-, or fibronectin-coated plates. Exogenously added soluble collagen, laminin, fibronectin, vitronectin or Matrigel failed to suppress ATRA-induced apoptosis. Results from the adhesion assay indicated that the cell attachment to fibronectin was significantly inhibited by ATRA. Treatment with perturbing antibody against integrin alpha5 or beta1 subunits resulted in promotion of ATRA-induced apoptosis. Moreover, the proteolytic cleavage of alpha5beta1 integrin and focal adhesion kinase (FAK) proteins is linked to the early phase of the ATRA-induced apoptotic process. Furthermore, ATRA-induced detachment, death, and cleavage of alpha5beta1 integrin and FAK were drastically suppressed by plating cells onto Matrigel-coated plates. These findings provide evidence that abrogation of cell adhesion, through proteolysis of alpha5beta1 integrin and FAK, is closely linked to ATRA-induced apoptosis in Hep3B cells.

Combined measurement of fetal nuchal translucency, maternal serum free beta-hCG, and pregnancy-associated plasma protein A for first-trimester Down's syndrome screening

PURPOSE

It has been proposed that first-trimester Down's syndrome screening has a higher detection rate compared to second-trimester biochemical screening. This study investigated the accuracy of Down's syndrome screening during gestational weeks 10 to 13 using the combination of fetal nuchal translucency (NT) measurement with maternal serum concentrations of free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A).

METHODS

A total of 1,514 women with singleton pregnancies were enrolled in this study. Fetal NT was measured using the criteria published by the Fetal Medicine Foundation. Maternal serum concentrations of free beta-hCG and PAPP-A were determined by microtiter-plate ELISA. Down's syndrome risk was calculated using multivariate Gaussian distribution and Alpha software.

RESULTS

Seventeen (1.12%) of the 1514 screened pregnancies had a fetal NT of at least 3 mm, and 41.2% of these had a poor pregnancy outcome, including four fetal aneuploidies. The odds of a fetal aneuploidy when the NT was greater than 2.0 multiples of median (MoM) was 90, when serum PAPP-A concentration was less than 0.45 MoM, it was 8.6, and when serum free beta-hCG concentration was greater than 2.2 MoM, it was 4.7. Using a risk cut-off level of 1 in 400, nine of 10 fetal aneuploidies were identified with a 4.7% false-positive rate, including two with trisomy 21, one with trisomy 18, and three with Turner's syndrome.

CONCLUSIONS

This study demonstrated that Down's syndrome screening using the combined test in the first trimester had a higher detection rate than that of serum screening in the second trimester. Implementation of NT measurement in the first trimester provides substantial advantages for Down's syndrome detection and early diagnosis of fetal structural abnormalities.

Formation and properties of proton-exchanged and annealed LiNbO3 waveguides for surface acoustic wave

The proton-exchanged (PE) and annealed PE (APE) z-cut LiNbO3 waveguides were fabricated using H4P2O7. The positive strain, c-axis lattice constant change (delta C/C), was calculated to be about +0.43%, which was almost independent of the exchanged conditions. The penetration depth of H measured by secondary ion mass spectrometry (SIMS) exhibited a step-like profile, which was assumed to be equal to the waveguide depth (d). The surface acoustic wave (SAW) properties of PE and APE z-cut LiNbO3 samples were investigated. The phase velocity (Vp) and electromechanical coupling coefficient (K2) of PE samples were significantly decreased by the increase of kd, where k was the wavenumber (2 pi/lambda). The insertion loss (IL) of PE samples was increased by the increase of kd and became nearly constant at kd > 0.064. The temperature coefficient of frequency (TCF) of PE samples showed an apparent increase with kd, reaching a maximum at kd = 0.292, then slightly decreased at higher kd. The effects of annealing resulted in a restoration of Vp and an improvement of IL.

Absence of nasal mucosal atrophy with fluticasone aqueous nasal spray

OBJECTIVE

To evaluate whether 1 year of continuous treatment with intranasal fluticasone propionate would lead to atrophy in the nasal mucosa compared with an active control, oral terfenadine.

DESIGN

Prospective, randomized, multicenter, open-label, parallel-group study.

SETTING

Two tertiary care academic institutions.

PATIENTS

Seventy-five subjects older than 18 years with perennial allergic rhinitis.

INTERVENTIONS

Patients received either fluticasone propionate aqueous nasal spray, 200 microg once daily, or terfenadine, 60 mg twice daily, for 1 year. Nasal biopsy specimens were obtained before and after 1 year of treatment and were evaluated for evidence of atrophy.

MAIN OUTCOME MEASURES

Epithelial and collagen layer thickness of the nasal mucosa as assessed by light microscopy and the presence and degree of edema, and regularity of collagen fibrils as assessed by electron microscopy. Analyses were performed without knowledge of subject identity or treatment assignment.

RESULTS

Neither fluticasone nor terfenadine treatment led to atrophy in the nasal mucosa by clinical or histologic observation. No significant changes from baseline were observed for any assessment of atrophy. In contrast to what would have been expected if atrophy were to occur, mean epithelial layer thickness in the fluticasone group significantly increased compared with terfenadine treatment (P = .03).

CONCLUSIONS

Treatment with intranasal fluticasone for 1 year increases the thickness of the nasal epithelium as compared with a year's treatment with terfenadine and does not lead to atrophy in the nasal mucosa. The increased thickness in the fluticasone treatment may represent repair from epithelial damage caused by chronic allergic inflammation.

An interesting observation of the position of some electronegative atoms in the taxol molecule

A study of the absolute energy-minimized configuration of the taxol molecule revealed that many oxygen atoms in this molecule and a nitrogen atom on the side chain are located on the same plane. A comparison of these electronegative atoms with information provided from existing literature indicated that most of these noted atoms conform with the reported structure--activity relationship (cytotoxicity, antineoplastic activity, tubulin assembly property, etc.). This observation may assist investigators in their future design of simpler, possibly clinically efficacious molecules related to taxol.

Early detection of hepatocellular carcinoma increases the chance of treatment: Hong Kong experience

The prognosis for patients with hepatocellular carcinoma (HCC) is poor because of the low chance of curative treatment. To increase the chance of intervention and to improve survival, early detection of subclinical HCC (SCHCC) by alpha-fetoprotein (AFP) and/or ultrasonography (USG) screening is implemented in many countries. Three hundred six Chinese patients with HCC diagnosed between January 1995 and December 1997 were recruited. They were categorized into two groups: 142 patients (group 1) had SCHCC diagnosed by screening (AFP and/or USG), and 164 patients (group 2) presented with symptomatic HCC. The tumor size was significantly smaller in group 1 compared with that of group 2 (3.5 cm vs. 8.1 cm; P <.0001). A significantly higher proportion of patients had bilobar involvement, multifocal HCC, diffuse-type HCC, portal vein infiltration, and distant metastasis in group 2 when compared with group 1. Operability and feasibility of treatment by transcatheter intra-arterial chemoembolization (TACE) in group 1 patients (26.8% and 45.1%, respectively) were significantly better than in group 2 patients (7.9% and 32.3%, P <.0001 and P =.03, respectively). The cumulative survival rate was significantly higher in group 1 than in group 2 (P <.0001). For those who had surgical resection and those who had TACE, group 1 patients had a higher cumulative survival rate compared with that of group 2 patients (P =.04 and P =.0003, respectively). Screening for HCC by AFP and/or USG can identify tumors at an early stage, resulting in a higher chance of receiving treatment. Whether it can improve survival requires a further prospective, randomized study.

Antituberculosis drug-related liver dysfunction in chronic hepatitis B infection

Liver toxicity is a common side effect of antituberculosis (anti-TB) drugs. We studied the differences in liver dysfunction observed during anti-TB treatment between hepatitis B virus carriers (HBV) and noncarriers. Three hundred twenty-four patients on anti-TB drugs were recruited and followed up for 1 year. Forty-three patients with HBV and 276 non-HBV patients were included for analysis. Liver function tests and viral markers were monitored monthly. Liver biopsy was requested whenever the alanine transaminase (ALT) was persistently abnormal. Eighty-six HBV carriers who were not given anti-TB drugs were chosen as a second control and evaluated prospectively. The incidence of liver dysfunction was significantly higher in HBV carriers given anti-TB drugs (34.9%) when compared to noncarriers (9.4%, P <.001) and with HBV carriers not given anti-TB drugs (8.1%, P <.001). For patients given anti-TB drugs, HBV carriers who developed liver dysfunction were younger (P =.011) and had more severe liver injury compared with noncarriers (P =.008). By multiple logistic regression analysis, age (P =.002) and hepatitis B infection (P <.001) were the only 2 significant risk factors for hepatotoxicity related to anti-TB therapy.

T1762/A1764 variants of the basal core promoter of hepatitis B virus; serological and clinical correlations in Chinese patients

BACKGROUND

A double variant in the basal core promoter, converting nucleotide 1762 from A to T (T1762) and nucleotide 1764 from G to A (A[764), has been described in patients with chronic hepatitis B infection. Its prevalence and significance in Chinese chronic HBV carriers are unknown.

METHODS

We studied 177 Chinese patients with chronic HBV infection (chronic hepatitis/asymptomatic: 89/88; hepatitis B e antigen positive/negative: 84/93). The double variant was detected by mismatched polymerase chain reaction and restriction fragment length polymorphism analysis. The reliability of this method was verified by sequencing in 41 serum samples with 100% matching.

RESULTS

The double variant T1762/ A1764 was found in 52 of 89 patients with chronic hepatitis, but in only 6 of 59 asymptomatic carriers (p<0.001). The prevalence was significantly lower in hepatitis B e antigen positive patients (23/84) than in hepatitis B e antigen negative patients (35/64) (p<0.005). Precore variant, A1896 was detected in 40 individuals; 31 of them suffered from chronic hepatitis and 9 were asymptomatic (p<0.001). A combination of both variants T1762/A1764 and A1896 was seen in 3 of 59 asymptomatic and 22 of 89 patients with chronic hepatitis (p<0.005).

CONCLUSIONS

Mismatched polymerase chain reaction with restriction fragment length polymorphism provides a reliable, easy and fast method for detection of the presence of the T1762/A1764 variant. In Chinese chronic hepatitis B carriers, T1762/A1764 variant was associated with both active liver disease and hepatitis B e antigen negativity.

Random X chromosome methylation patterns in the carriers with clinical phenotypic expressions of X-linked recessive bulbospinal neuronopathy

OBJECTIVES

We report the unusual phenotypic expression in 2 female carriers of a family with X-linked recessive bulbospinal neuronopathy (X-BSN). We analyze the methylation pattern of the androgen receptor (AR) gene to inspect the possibility of non-random X chromosome inactivation to be the underlying mechanism.

MATERIAL AND METHODS

Twenty-three members in 3 generations of a Taiwanese family were examined and studied for genomic DNA analysis. We analyzed the sequence of the first exon of the AR gene to identify the numbers of CAG repeats, and to determine the methylation pattern by using the restriction enzymes HpaII and HhaI.

RESULTS

There were 3 probands and 5 carriers and 2 of the carriers manifested clinical symptoms. Sequence analysis revealed that the numbers of trinucleotide repeats ranged from 42 to 45 in one allele of the X-chromosome in the 5 female carriers. The restriction pattern of the HpaII and HhaI recognizable sites of the X-chromosome indicated a random methylation.

CONCLUSION

Our data suggest that molecular genetic studies are important in confirming the diagnosis of X-BSN and early detection of female carriers, and the random or non-random methylation pattern of the X-chromosome is not a determining factor for partial expression of the abnormal AR gene in some carriers.

Mannose binding lectin gene mutations are associated with progression of liver disease in chronic hepatitis B infection

Mannose-binding lectin (MBL) plays an important role in immune defense. We examined the MBL gene mutations and MBL levels in Chinese hepatitis B and hepatitis C patients with and without symptomatic cirrhosis. We recruited 190 hepatitis B and C patients, and 117 normal Chinese as controls. Serum MBL levels were measured by enzyme-linked immunosorbent assay. MBL gene mutation at codons 52, 54, and 57 was detected by polymerase chain reaction (PCR) assay. In asymptomatic hepatitis B and C patients, there was no increase in codons 52, 54, and 57 mutation, but the MBL levels were significantly lower than those in the controls. Codon 54 mutation rate was increased to 44.4% (P =.007) in symptomatic hepatitis B cirrhosis and 64.3% (P =.0026) in patients with spontaneous bacterial peritonitis (SBP). There was no increase in codon 54 mutation rate in hepatitis B-related hepatocellular carcinoma (HCC). In chronic hepatitis B infection, the odds ratio for an individual with codon 54 mutation to develop cirrhosis was 1.84 (95% CI: 1.21-2. 81) and to develop SBP was 4.58 (95% CI: 1.73-12.16). Chronic hepatitis B and hepatitis C infection lowered the MBL levels, probably by suppressing MBL production. Codon 54 mutation of MBL was associated with progression of disease in chronic hepatitis B infection.

Twelve-year follow-up of a prospective randomized trial of hepatitis B recombinant DNA yeast vaccine versus plasma-derived vaccine without booster doses in children

A total of 318 children were prospectively randomized in group 1 with two 5-microg doses of recombinant vaccine given at 0 and 1 month; in group 2 with three 5-microg doses of recombinant vaccine given at 0, 1, and 6 months; or in group 3 with three doses of plasma-derived vaccine given at 0, 1, and 6 months. Eleven subjects with a hepatitis B surface antigen antibody (anti-HBs) titer of less than 10 mIU/mL at 12 months were given an extra dose of vaccine and were excluded from analysis. No booster doses were given to any other subjects. All children were followed up yearly for the level of anti-HBs titers and for the detection of hepatitis B infection. At the 12th year of follow-up, there were significantly fewer subjects with anti-HBs of 10 mIU/mL or above in group 1 (60.4%) when compared with group 2 (81.4%; P =.0287) and group 3 (79.0%; P =. 0381). The geometric mean titers (GMTs) of subjects of group 1 were significantly lower than those of group 2 and group 3 throughout the 12 years of follow-up. A total of 65 subjects had one or more episodes of anamnestic response. No subject became positive for hepatitis B surface antigen (HBsAg); 2 became positive for hepatitis B core antigen antibody (anti-HBc). In conclusion, the long-term protective immunity was better with three doses of hepatitis B vaccine (either the recombinant or plasma-derived) than with two doses. However, protection from hepatitis B infection could be equally achieved by either two doses or three doses of the vaccine. Booster doses were not necessary, probably because of effective anamnestic response.

Design of antineoplastic agents based on the "2-phenylnaphthalene-type" structural pattern. 4. Synthesis and biological activity of 2-chloro-3-(substituted phenoxy)-1, 4-naphthoquinones and related 5,8-dihydroxy-1,4-naphthoquinones

The intermediate in the preparation of 1,3,7, 10-tetrahydroxybenzo[b]naphtho[2,3-d]furan-6,11-dione (2), 2-chloro-5,8-dimethoxy-3-(3,5-dimethoxyphenoxy)-1,4-naphthoquinone (8h), and corresponding hydroxyl, methoxyl, and acetoxyl analogues was found to possess interesting inhibitory activities in a number of cytotoxic test systems. Activities were also noticed in some 5, 8-dihydroxy-1,4-naphthoquinone derivatives. A structure-activity discussion of compounds of this series is presented. The newly uncovered biological activity of 2-chloro-3-(substituted phenoxyl)-1, 4-naphthoquinones and 2,3-bis(substituted phenoxy)-1, 4-naphthoquinones may suggest an approach for the development of new classes of antineoplastic agents.

Failed adoptive immunity transfer: reactivation or reinfection?

A 26-year-old female bone marrow transplant (BMT) recipient was hepatitis B surface antigen (HBsAg) and hepatitis B e antibody (HBeAb) positive. The donor, her human leucocyte antigen (HLA)-compatible sister, was HBsAg negative but hepatitis B surface antibody (HBsAb) and hepatitis B core antibody (HBcAb) positive. Twelve weeks post-BMT the patient became HBsAg negative, as determined using a monoclonal antibody-based assay. At 16 weeks post-BMT, HBsAg became undetectable by monoclonal and polyclonal immunoassay with seroconversion to HBsAb; however, at 24 weeks post-BMT the patient again became HBsAg positive. Both the recipient and the donor were retrospectively tested by hepatitis B virus (HBV) polymerase chain reaction (PCR) and found to be positive. The recipient displayed variants at amino acids 4 and 47 of the surface (S) gene prior to BMT. These mutations were not detected 32 weeks post-BMT when the S gene sequence was identical to that of an adr prototype. The donor was found to have four unique amino acid substitutions at positions 30, 98, 101 and 210 of the S gene. However, in vitro-expressed HBsAg from the donor was detected by commercial kits and an immunofluorescence assay, indicating that antigenic alteration did not explain HBsAg negativity. This donor highlights the value of PCR as the gold standard test for current HBV infection. It also demonstrates that discordance between two commercial HBsAg assays may not always be caused by antigenic variants. The second episode of hepatitis may theoretically have been caused by reactivation, selection of an escape mutant by HBsAb, reinfection or recombination. We suggest it was reactivation because none of the donor variants was seen in the recipient post-BMT.

Affinity capillary electrophoresis in biomolecular recognition

Affinity capillary electrophoresis is a new method for studies of biomolecular recognition. Applications reported in the literature include chiral separation of racemic biomolecules, measurement of binding constants, estimation of kinetic on- and off-rate constants, determination of binding stoichiometries (a useful tool in examining electrostatic interactions), estimation of effective charges and molecular weights of proteins, characterization of enzymatic activities and library screening for tight-binding drug candidates in solution. This technique demands only small amounts of sample (nanolitre injection volumes, picograms of proteins), involves no radiolabelled materials or chemically immobilized ligands, and does not require changes in spectroscopic characteristics upon binding. This paper reviews the most recent applications of affinity capillary electrophoresis and its use in the analysis of biomolecules.

Increase of reactive oxygen species (ROS) in endothelial cells by shear flow and involvement of ROS in shear-induced c-fos expression

Intracellular reactive oxygen species (ROS) may participate in cellular responses to various stimuli including hemodynamic forces and act as signal transduction messengers. Human umbilical vein endothelial cells (ECs) were subjected to laminar shear flow with shear stress of 15, 25, or 40 dynes/cm2 in a parallel plate flow chamber to demonstrate the potential role of ROS in shear-induced cellular response. The use of 2',7'-dichlorofluorescin diacetate (DCFH-DA) to measure ROS levels in ECs indicated that shear flow for 15 minutes resulted in a 0.5- to 1.5-fold increase in intracellular ROS. The levels remained elevated under shear flow conditions for 2 hours when compared to unsheared controls. The shear-induced elevation of ROS was blocked by either antioxidant N-acetyl-cysteine (NAC) or catalase. An iron chelator, deferoxamine mesylate, also significantly reduced the ROS elevation. A similar inhibitory effect was seen with a hydroxyl radical (.OH) scavenger, 1,3-dimethyl-2-thiourea (DMTU), suggesting that hydrogen peroxide (H202), .OH, and possibly other ROS molecules in ECs were modulated by shear flow. Concomitantly, a 1.3-fold increase of decomposition of exogenously added H2O2 was observed in extracts from ECs sheared for 60 minutes. This antioxidant activity, abolished by a catalase inhibitor (3-amino-1,2,4-triazole), was primarily due to the catalase. The effect of ROS on intracellular events was examined in c-fos gene expression which was previously shown to be shear inducible. Decreasing ROS levels by antioxidant (NAC or catalase) significantly reduced the induction of c-fos expression in sheared ECs. We demonstrate for the first time that shear force can modulate intracellular ROS levels and antioxidant activity in ECs. Furthermore, the ROS generation is involved in mediating shear-induced c-fos expression. Our study illustrates the importance of ROS in the response and adaptation of ECs to shear flow.

X-linked recessive bulbospinal neuronopathy: clinical and molecular studies in a Taiwanese family

We describe clinical, biochemical, and molecular studies on a Taiwanese family with X-linked recessive bulbospinal neuronopathy. There were three probands and five female carriers among the 23 members examined. The clinical manifestations included progressive muscle weakness, diffuse fasciculation, postural tremor, muscle cramps, dysarthria, dysphagia, diabetes, and gynecomastia. Phenotypic expression varied among the affected subjects. Two carriers also had postural tremor and perioral fasciculation. Endocrine tests were normal except for a mild increase in serum testosterone and/or growth hormone in one patient and one carrier. Type IV hyperlipoproteinemia was observed in two patients, one carrier, and one healthy offspring. Molecular genetic studies confirmed elongation of the CAG triplet repeat in exon 1 of the gene for the androgen receptor. Sequence analysis showed that there were 42 to 43 CAG repeats in the three probands and 42 to 45 in the five carriers. The mutant allele had a tendency to increase by one or two repeats from one generation to the next. The length of CAG repeats at which the mutant allele became unstable was shorter in our family than in previous reports. The normal allele was also unstable and had a tendency to shrink by one of five repeats during transmission. These findings suggest that the number of CAG triplet repeats is variable in both the mutant and normal alleles.

Primary hyperparathyroidism with cardiac abnormalities: a case report

Primary hyperparathyroidism, characterized by hypersecretion of parathyroid hormone (PTH) leading to hypercalcemia and relative hypophosphatemia, is quite common in the elderly. Most patients with primary hyperparathyroidism have only mild hypercalcemia and are symptomless. But others experience various other organ diseases. Primary hyperparathyroidism is also associated with cardiovascular abnormalities, including QT interval shortening, heart block, cardiac arrhythmias, hypertension, myocardial hypertrophy, myocardial calcification and, though rarely, with valvular heart disease. We described a case of primary hyperparathyroidism associated with cardiac abnormalities. An 82-year-old male presented with the complaints of chest discomfort, fatigue, general weakness, nausea and vomiting over a period of months and was admitted in July 1996. Physical examination with heart auscultation showed a pansystolic murmur over the right sternal border and apex region, and a blowing diastolic murmur over the left sternal border. Biochemistry profiles revealed elevations of serum calcium (14.3 mg/dl) and chloride/phosphate ratio (> 33). Endocrinological studies showed elevations of serum PTH-C (4.8 ng/ml) and PTH-intact (705 pg/ml) concentrations. Kidney ultrasonography revealed a left renal stone. A spine X-ray revealed spondylosis and a compression fracture of the lumbar-spine with osteoporotic change. Thyroid ultrasonography and Thallium (Tl201)-technetium (Tc99m) subtraction scan showed parathyroid adenoma in the low pole of the right thyroid bed. Parathyroid aspiration cytology revealed few and discrete cells. Echocardiogram revealed moderate to severe aortic valvular calcification as well as stenosis with moderate aortic regurgitation, mitral regurgitation and myocardial calcification. The patient received parathyroidectomy one month later. During his postoperative days, he suffered from muscle twitching with positive Trousseau's sign and Chvostek's sign. The patient received calcium carbonate and vitamin D for hypocalcemia, diltiazem and capoten for his heart problems. A repeated echocardiogram two months after surgery showed no improvement of valvular calcification.

Reduced folate carrier gene (RFC1) expression and anti-folate resistance in transfected and non-selected cell lines

Methotrexate transport deficiency due to decreased reduced folate carrier (RFC) activity has been observed in several cell lines selected for resistance to methotrexate (MTX). Since MTX resistance is multifactorial, however, it is difficult to quantify the relative importance of changes in RFC activity in selected cell lines and even more so to determine the relative contribution of naturally occurring RFC activity in the MTX sensitivity of non-selected cell lines. We examined the role of RFC in MTX resistance by studying a transport-deficient cell line transfected with the gene for human RFC, RFC1, and by correlating relative RFC1 expression with MTX and trimetrexate (TMTX) growth inhibition (GI50) in a panel of cell lines used in the NCI Anticancer Drug Screen. Clones of transport-deficient, MTX-resistant ZR-75-1 human breast cancer cells (MTX(R) ZR-75-1) transfected with RFC1 were 250-fold more sensitive to MTX and 300-fold more resistant to TMTX than control cell clones, showing that restoration of RFC activity has a significant impact on MTX and TMTX cytotoxicity. We also surveyed 40 of the 60 cell lines in the NCI drug screen panel for RFCI RNA levels by a quantitative RT-PCR assay. RFCI RNA levels varied over a range of 15-fold, with only 1 cell line found to be null in expression. Using data from the 6-day drug exposure assay, RFC1 correlated positively with MTX and negatively with TMTX cytotoxicity. As predicted by transfection studies, the calculated difference between MTX and TMTX potency was even more strongly correlated with RFC1 RNA levels of the cell lines. In addition, compounds in the NCI Anticancer Drug Screen database with cytotoxicity profiles which correlated with RFC1 RNA levels or with the calculated difference in MTX-TMTX potency were examined for MTX uptake inhibition and cytotoxicity in the RFC1-transfected MTX(R) ZR-75-1 cell line. Overall, our data demonstrate the importance of RFC1 in MTX resistance both as a transgene and as a constitutively expressed gene in non-selected cell lines.

Bilateral increases in histamine after unilateral nasal allergen challenge

Studying the inflammatory response that follows the early response to nasal challenge with antigen provides a better understanding of allergic rhinitis than just studying the immediate (early) response. Nine allergic volunteers were challenged unilaterally with antigen-containing discs, and bilateral changes in physiologic responses as well as in the concentration of histamine in nasal secretions were measured for 11 h. We found significant immediate increases in symptoms, sneezes, ipsilateral nasal airway resistance, and ipsilateral histamine in the early phase response. Two-thirds of the allergen-challenged volunteers showed increases in physiologic parameters or histamine in the hours after allergen challenge. The pooled data of all subjects exhibited significant increases in bilateral nasal airway resistance and in ipsilateral and contralateral histamine, hours after unilateral provocation. These responses differed significantly from control subjects. In another group of 11 volunteers challenged ipsilaterally with antigen, the number of basophils increased both on the side of challenge and on the contralateral side. The magnitude of the increase on the ipsilateral side correlated with the increase on the contralateral side (r(s) = 0.72). The basophils are the most likely source of the contralateral increase in histamine as they are on the ipsilateral side. Although the mechanisms underlying this contralateral increase in basophils and histamine are not known, we speculate that delayed, neurogenic responses play a contributory role.

Accessory atrioventricular pathways with only antegrade conduction in patients with symptomatic Wolff-Parkinson-White syndrome. Clinical features, electrophysiological characteristics and response to radiofrequency catheter ablation

Information about accessory pathways conducting only in the antegrade direction is limited. The purposes of the present study were to prospectively investigate the clinical features, electrophysiological characteristics, effects of radiofrequency catheter ablation and recurrent atrial fibrillation after successful ablation in patients with accessory pathways conducting only in the antegrade direction, and to compare them with those who had pathways capable of bidirectional conduction in a consecutive series of 759 patients. Electrophysiological studies and radiofrequency catheter ablation were performed in 33 study patients with antegrade-only accessory pathways and in 377 patients with bidirectional accessory pathways for comparison. The patients with accessory pathways conducting only in the antegrade direction were older (47 +/- 16 vs 40 +/- 16 years, P = 0.037) and had a higher incidence of atrial fibrillation (100% vs 27.1%, P < 0.001) as well as related syncope (33.3% vs 10.1%, P = 0.001). The study patients also had more accessory pathways located in the posterior septum and a higher incidence of retrograde atrioventricular nodal conduction. The biophysical variables, success and complication rates of radiofrequency ablation were similar in both groups. During the follow-up period of 32 +/- 12 months, symptomatic atrial fibrillation after successful ablation did not recur in 79% and 81% of patients with unidirectional and bidirectional accessory pathways, respectively. Furthermore, old age and cardiovascular diseases were independent predictors of recurrent atrial fibrillation after radiofrequency ablation. In conclusion, this study showed that atrial fibrillation with preexcitation was the usual presentation in patients who had symptomatic Wolff-Parkinson White syndrome with an antegrade-only accessory pathway, and might be related to antegrade conduction of the accessory pathway. Therefore elimination of antegrade-only and bidirectional pathways by radiofrequency ablation could prevent the recurrence of symptomatic atrial fibrillation in younger patients without cardiac disease.

Paradox of accessory pathway block after radiofrequency ablation in patients with the Wolff-Parkinson-White syndrome

Although pacing technique has demonstrated that the most common site of conduction block in a manifest accessory pathway (AP) was between the AP and the ventricle, most of the block sites have been found to be between the atrium and AP after successful radiofrequency ablation. Furthermore, the block site in a concealed AP after successful radiofrequency catheter ablation has not been reported in the literature, and comparisons between a manifest and concealed AP have not been performed. This study included 219 consecutive patients undergoing successful radiofrequency catheter ablation of a single AP. AP potential was recorded at the successful target site in 76 of 92 (82.6%) patients with manifest APs, and in 99 of 127 (77.9%) patients with concealed APs. All the left-sided APs (including left posteroseptal APs) were ablated by a ventricular approach, and right-sided APs (including anteromidseptal and right posteroseptal APs) were ablated by an atrial approach. The site of conduction block was determined by analyzing and comparing the local electrograms recorded before and after radiofrequency ablation at successful ablation sites. Conduction block of manifest APs was between the atrial-AP (A-AP) in 69 patients (75%) and between the AP-ventricle (AP-V) interface in 7 patients (7.6%), whereas the conduction block of concealed APs occurred between the AP-V in 90 patients (70.9%) and between the A-AP interface in 9 patients (7.1%). Neither the preablation electrogram nor electrophysiologic characteristics of APs predicted the site of conduction block. Furthermore, neither the location of the APs nor the position of the ablation catheter affected the block site. It was concluded that the most common site of conduction block during successful radiofrequency catheter ablation of a manifest and concealed AP was between the A-AP and AP-V interface, respectively, and the impedance mismatch theory explained only part of the findings.

Form-birefringent computer-generated holograms

Polarization-selective computer-generated holograms made with form-birefringent nanostructures were designed, fabricated, and evaluated experimentally at 1.5 microm. The fabricated element showed a large polarization contrast ratio (>250:1) and a high diffraction efficiency (>40% for a binary phase level element). The experimental evaluation was in good agreement with the design and modeling predictions.

Effect of dietary L-glutamine on the hepatotoxic action of D-galactosamine in rats

The protective effect of dietary L-glutamine against the hepatotoxic action of D-galactosamine (GaIN) was investigated by model experiments with rats. Rats fed with 20% casein diets containing 10% free amino acids were injected with GaIN, and the serum aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase activities and the hepatic glycogen content were assayed 20 hours after the injection. These enzyme activities in the group fed with 10% L-glutamine diet for 8 days were lower than those in the groups fed with the control, 10% L-glutamic acid and 10% L-alanine diets for 8 days. The more prolonged the feeding period with the 10% L-glutamine diet was, the more the serum activity levels of such enzymes were decreased. Although neomycin also lowered these enzyme activities, its simultaneous ingestion with neomycin did not show any additive or synergistic effect. The hepatic glycogen content in the 10% glutamine group still remained high after the GaIN treatment. It is therefore assumed that the effectiveness of glutamine intake would have been mediated by glycogen metabolism rather than by uridine metabolism.

Modulation of [3H]quinpirole binding in brain by monoamine oxidase inhibitors: evidence for a potential novel binding site

[3H]Quinpirole is a dopamine agonist with high affinity for the D2 and D3 dopamine receptor subtypes. A variety of drugs, most notably monoamine oxidase inhibitors (MAOls), inhibit the binding of [3H]quinpirole, but not [3H]spiperone or [3H](-)N-n-Propylnorapomorphine, in rat striatal membranes by a mechanism that does not appear to involve the enzymatic activity of MAO. This study extends the characterization of MAOI-displaceable [3H]quinpirole binding in rat brain. Clinically antidepressant MAOIs exhibited selectivity between sites labeled by [3H]quinpirole and [3H]spiperone as did a number of structurally related propargylamines and N-acylethylenediamine derivatives and other drugs such as debrisoquin and phenylbiguanide. The MAOIs clorgyline and Ro 41-1049 were the most potent. Anti-depressant MAOIs inhibited [3H]quinpirole binding with the following rank order of potency: phenelzine > pargyline > tranyl-cypromine > isocarboxazid > nialamide > moclobemide. In striatal membranes, MAOI Ro 41-1049 inhibited [3H]quinpirole binding with similar potency at a variety of incubation temperatures (4-37 degrees C), assay tissue concentrations (5-20 mg original wet weight/ml), and time points (2 min-4 hr) and in the presence or absence of K+, Mg2+, Ca2+ ions, ascorbate, EDTA and NaCl. The regional distribution of Ro 41-1049-displaceable [3H]quinpirole binding in brain paralleled that of D2-like receptors. These data suggest that MAOIs interact with a novel binding site that is labeled by [3H]quinpirole or that modulates [3H]quinpirole binding. This site may be associated with D2-like dopamine receptors.

Longitudinal clinical and electrophysiological assessment of patients with symptomatic Wolff-Parkinson-White syndrome and atrioventricular node reentrant tachycardia

BACKGROUND

Functional changes of the accessory AV pathways and dual AV node pathways are very important for patients with Wolff-Parkinson-White syndrome or AV node reentrant tachycardia who refuse to receive long-term medication or radiofrequency catheter ablation. However, no studies of serial clinical and electrophysiological characteristics in these patients have been performed.

METHODS AND RESULTS

One hundred thirteen patients with Wolff-Parkinson-White syndrome or AV node reentrant tachycardia were included in this study. The first and second follow-up electrophysiological studies were performed in years 5 and 10 after the baseline study, respectively. Conduction properties of the accessory pathways became poor over time. After a mean follow-up period of 9 +/- 1 years, antegrade ventricular preexcitation and retrograde accessory pathway conduction disappeared in 22.5% and 7.8% (P < .01), respectively; dual AV node pathway physiology persisted and retrograde fast pathway disappeared in 10.8% of the patients. Baseline conduction properties of the antegrade and retrograde accessory pathways and the retrograde fast pathway independently predicted late loss of conduction. Spontaneous disappearance of the original tachyarrhythmias occurred in 10.3% of all patients, and newly developed tachyarrhythmias in 15.2%. The incidence (38.5%) of newly developed atrial fibrillation was significantly higher in patients with manifest accessory pathways. Furthermore, symptom scores and attack frequency increased significantly over time in the patients with accessory pathways and AV node reentrant tachycardia.

CONCLUSIONS

Disappearance of the original tachycardia and changing patterns of tachycardia, also with an increase in symptom scores and attack frequency, suggested that a detailed evaluation of these events is important and early intervention with radiofrequency ablation would be helpful.