Application of membrane-coupled anaerobic volatile fatty acids fermentor for dissolved organics recovery from coagulated raw sludge

To investigate the treatment performance of membrane-coupled anaerobic volatile fatty acids fermentor system, the effects of operational parameters for volatile fatty acids production were evaluated through experiments and a mathematical model. The volatile fatty acids recovery ratio was largely affected by the change of hydraulic retention time, reaching its maximum value at 12 hrs. Over the range of hydraulic retention time 8 to 96 hrs, the volatile fatty acids recovery ratio decreased with the increase of hydraulic retention time above 12 hrs, while the ratio of mineralization and gasification increased. Hydraulic retention time and membrane filtration ratio should be maintained less than 1 day and above 0.9, respectively, to attain over 40% of organic materials recovery ratio at 10 days of solids retention time. When the hydrolysis rate constant was 0.01 hr-1, the organic loading rate should be maintained at above 1.0 (kgC/m3/day) to attain over 45% of volatile fatty acids recovery ratio. Based on experimental and simulated results, membrane-coupled anaerobic volatile fatty acids fermentor system was thought to be effective for dissolved organics recovery from coagulated sewage sludge.

A Monte Carlo study of radiation transport through multileaf collimators

Due to the significant increase in the number of monitor units used to deliver a dynamic IMRT treatment, the total MLC leakage (transmission plus scatter) can exceed 10% of the maximum in-field dose. To avoid dosimetric errors, this leakage must be accurately accounted for in the dose calculation and conversion of optimized intensity patterns to MLC trajectories used for treatment delivery. In this study, we characterized the leaf end transmission and leakage radiation for Varian 80- and 120-leaf MLCs using Monte Carlo simulations. The complex geometry of the MLC, including the rounded leaf end, leaf edges (tongue-and-groove and offset notch), mounting slots, and holes was modeled using MCNP4b. Studies were undertaken to determine the leakage as a function of field size, components of the leakage, electron contamination, beam hardening and leaf tip effects. The leakage radiation with the MLC configured to fully block the field was determined. Dose for 6 and 18 MV beams was calculated at 5 cm depth in a water phantom located at 95 cm SSD, and normalized to the dose for an open field. Dose components were scored separately for radiation transmitted through and scattered from the MLC. For the 80-leaf MLC at 6 MV, the average leakage dose is 1.6%, 1.7%, 1.8%, and 1.9% for 5 x 5, 10 x 10, 15 x 15, and 20 x 20cm2 fields, respectively. For the 120-leaf MLC at 6 MV, the average leakage dose is 1.6%, 1.6%, 1.7%, and 1.9% for the same field sizes. Measured leakage values for the 120-leaf MLC agreed with calculated values to within 0.1% of the open field dose. The increased leakage with field size is attributed to MLC scattered radiation. The fractional electron contamination for a blocked MLC field is greater than that for an open field. The MLC attenuation significantly affects the photon spectrum, resulting in an increase in percent depth dose at 6 MV, however, little effect is observed at 18 MV. Both phantom scatter and the finite source size contribute to the leaf tip profile observed in phantom. The results of this paper can be applied to fluence-to-trajectory and trajectory-to-fluence calculations for IMRT.

Fixation of a modified covered esophageal stent: its clinical usefulness for preventing stent migration

BACKGROUND AND STUDY AIMS

Membrane-covered self-expandable metal stents are effective in preventing tumor ingrowth and stent obstruction in patients with inoperable esophageal cancer, but migration of stents continues to be a major problem. We therefore constructed a modified covered self-expandable esophageal metal stent capable of being fixed using a silk thread. The stent was studied prospectively to define its palliative characteristics and whether it is effective in preventing migration.

PATIENTS AND METHODS

Modified covered self-expandable metal stents were placed in 17 patients with malignant gastric cardiac cancer involving the esophagogastric junction, 41 patients with esophageal cancer, and three patients with tracheoesophageal fistulas. Clinical and radiographic follow-up examinations were carried out at regular intervals.

RESULTS

Placement of the stent was successful in all patients, with good symptomatic relief and no serious stent-related complications such as esophageal perforation or hemorrhage. Acute stent placement problems, such as incomplete expansion or acute angulation of the stent, were noted in four patients. However, during a mean follow-up period of 7.5 months (range 1 to 17 months), there was no stent migration.

CONCLUSIONS

Modified covered self-expandable esophageal metal stents of this type would be very effective in preventing stent migration, especially in patients with malignant gastric cardiac cancer extending to the lower esophagus, those with short-segment esophageal cancer, and those with tracheoesophageal fistulas.

The role of percutaneous transhepatic papillary balloon dilation in percutaneous choledochoscopic lithotomy

BACKGROUND

When choledochoscopic lithotomy with basket and electrohydraulic lithotripsy is used to remove intrahepatic duct stones, fragments or small stones usually remain in the bile duct that are too small to be captured with a basket.

METHODS

An attempt was made to remove stone fragments in 16 patients with intrahepatic duct stones by antegrade balloon dilation of the sphincter of Oddi with a conventional balloon catheter. After balloon dilation, remnant stones and sludge were pushed through the papilla with the choledochoscope.

RESULTS

Bile duct stones were completely removed in 12 of 16 patients (75%); stones were removed in 1 session. There was no clinical evidence of procedure-related pancreatitis or fatal complications.

CONCLUSIONS

Percutaneous transhepatic papillary balloon dilation of the sphincter of Oddi and clearance of remnant bile duct stones and stone fragments with the tip of choledochoscope is simple and effective in patients undergoing percutaneous transhepatic choledochoscopic lithotomy.

Arthroscopic anterior cruciate ligament reconstruction with quadriceps tendon composite autograft

At present, no single graft option clearly outperforms another. Autografts (patellar tendon, hamstring) and allografts (Achilles tendon, patellar tendon) are the grafts most often used. However, each grafts has advantages and disadvantages. Quadriceps tendon graft for anterior cruciate ligament reconstruction is not new, but an alternative composite graft is introduced here that consists of quadriceps tendon-patellar bone and bone obtained from a coring reamer used to create the tibial tunnel. This composite graft retains reduced morbidity while allowing the secure bone-to-bone fixation associated with bone-patellar tendon-bone graft.

Monte Carlo dose calculations for dynamic IMRT treatments

Dose calculations for intensity modulated radiation therapy (IMRT) face new challenges due to the complex leaf geometry and time dependent nature of the delivery. A fast method of particle transport through a dynamic multileaf collimator (MLC) geometry that accounts for photon attenuation and first-scattered Compton photon production has been incorporated into an existing Monte Carlo code used for patient dose calculations. Dosimetric agreement between calculation and measurement for two photon energies and MLC types is within experimental error for the sliding window tests. For a patient IMRT field, the Monte Carlo calculations are closer to measured dose than similar superposition or pencil beam calculations.

Pyogenic spondylitis in an S1-S2 immobile segment

STUDY DESIGN

A case of pyogenic spondylitis in S1-S2 is presented.

OBJECTIVE

To describe the diagnosis and management of this rare spondylitis.

SUMMARY OF BACKGROUND DATA

The segment including the first and second sacral vertebrae is not mobile. Therefore, discitis of S1-S2 and adjacent spondylitis is very rare. To the authors' knowledge, this is the first reported case of infectious spondylitis in an immobile segment: S1-S2.

METHODS

In addition to radiography and bone scintigraphy, magnetic resonance imaging was used to confirm the diagnosis. Changes consistent with infectious spondylitis were shown, including an epidural abscess.

RESULTS

The patient was treated with laparoscopic drainage and biopsy. Staphylococcus aureus was cultured, and adequate antibiotics were administered. Repeat magnetic resonance imaging at approximately 4 months demonstrated normal signal intensity and disappearance of the abscess.

CONCLUSION

Findings from this study show that pyogenic spondylitis can occur in immobile S1-S2.

Prediction of a membrane-coupled anaerobic VFA fermenter efficiency using an empirical model

An empirical model based on some statistical analysis for predicting produced volatile fatty acids (VFA) concentration was developed to establish reliable design conditions of a membrane-coupled anaerobic VFA fermenter (MCAVF) and assess its performance with influent organics concentration (Ci), membrane filtration ratio (phi) and hydraulic loading rate (HLR). The empirical model followed the same trend as the experimental data, which showed the effectiveness of the model. The relationship involving these three independent variables explained more than 90% of the variation in the dependent variable. A model explains that the produced VFA concentration is more sensitive to changes in influent organics concentration (Ci) and membrane filtration ratio (phi) than hydraulic loading rate (HLR). This empirical model can predict the optimum values of operation parameters on many scenarios. Due to its simplicity, the empirical model can be used to design and operate a membrane-coupled anaerobic VFAs fermenter.

Effective combination of microfiltration and intermittent ozonation for high permeation flux and VFAs recovery from coagulated raw sludge

This research was conducted to investigate the effect of intermittent ozonation on permeation flux recovery and production for soluble organic materials in a membrane-coupled anaerobic VFAs fermenter (MCAVF) system. Flux recovery ratio exceeded 80% with 22.2 gO3 l-1 of ozone injection and then showed nearly 95% with 43 gO3 l-1 in batch experiment. Under the same ozone concentration, extending contact time was more effective than increasing bubbling dose rate for flux recovery. In continuous-flow operation, the value of average permeation flux was 0.69 m3 m-2 d-1 during without ozonation period, while average permeation flux for 70 days with intermittent ozone bubbling was 1.17 m3 m-2 d-1 that corresponds to 1.7 times that with no ozonation period. Moreover, in spite of intermittent ozone bubbling for 70 days, significant inhibition was not observed for volatile fatty acids (VFAs) producing bacteria and VFAs production. It was found that the average value of [permeates total organic carbon (TOC) concentration: Influent TOC concentration] with ozonation period was about 1.5 times higher than that of no ozonation period. Consequently, it is believed that a membrane-coupled anaerobic VFAs fermenter (MCAVF) process combined with intermittent ozonation is suitable to overcome the flux decline of membrane and simultaneously is useful to the recovery of soluble organic materials from coagulated raw sludge.

Effect of hydraulic loading rate on acidogenesis in a membrane-coupled anaerobic VFAs fermenter

A membrane-coupled anaerobic VFAs fermenter (MCAVF) was operated with five different hydraulic loading rates (3, 2, 1, 0.5 and 0.25 day-1) to evaluate its influence on acid phase VFAs production from coagulated raw sludge. Results show that C2 to C5 volatile fatty acids were formed as predominant compounds. At constant solids retention time (SRT) of 10 days, VFAs production ratio moderately increased over the range of hydraulic loading rate (HLR) of 3 day-1 to 2 day-1, but significantly decreased at other HLR conditions. First order hydrolysis rate constant decreased with a decrease in HLR. The relatively high degradation percentages of carbohydrate and protein were observed, ranging from 25 to 47%, 27 to 47%, respectively. However, lipid and fiber component were degraded at much lower ratio than the previous other two organic materials. On the other hand, despite some variation in the minor acids in five HLR cases, VFAs speciation appeared to be independent of HLR. The results obtained emphasize that; at least in the range investigated, the optimal HLR for VFAs production and recovery from coagulated raw sludge is in the range of 2 day-1 and 1 day-1.

Cloning and characterization of thermostable endoglucanase (Cel8Y) from the hyperthermophilic Aquifex aeolicus VF5

Aquifex aeolicus is the hyperthermophilic bacterium known, with growth-temperature maxima near 95 degrees C. The cel8Y gene, encoding a thermostable endoglucanase (Cel8Y) from Aquifex aeolicus VF5, was cloned into a vector for expression and expressed in Escherichia coli XL1-Blue. A clone of 1.7 kb fragment containing endoglucanase activity, designated pKYCY100, was sequenced and found to contain an ORF of 978 bp encoding a protein of 325 amino acid residues, with a calculated molecular mass of 38,831 Da. This endoglucanase was designated cel8Y gene. The endoglucanase has an 18-amino-acid signal peptide but not cellulose-binding domain. The endoglucanase of A. aeolicus VF5 had significant amino acid sequence similarities with endoglucanases from glycosyl hydrolase family 8. The predicted amino acid sequence of the Cel8Y protein was similar to that of CMCase of Cellulomonas uda, BcsC of Escherichia coli, CelY of Erwinia chrysanthemi, and CMCase of Acetobacter xylinum. The molecular mass of Cel8Y was calculated to be 36,750 Da, which is consistent with the value obtained from result of CMC-SDS-PAGE of the purified enzyme. Cel8Y was thermostable, exhibiting maximal activity at 80 degrees C and pH optima of 7.0 and with half-lives of 2 h at 100 degrees C, 4 h at 90 degrees C.

A mechanistic study of the antibacterial effect of silver ions on Escherichia coli and Staphylococcus aureus

To investigate the mechanism of inhibition of silver ions on microorganisms, two strains of bacteria, namely Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), were treated with AgNO(3) and studied using combined electron microscopy and X-ray microanalysis. Similar morphological changes occurred in both E. coli and S. aureus cells after Ag(+) treatment. The cytoplasm membrane detached from the cell wall. A remarkable electron-light region appeared in the center of the cells, which contained condensed deoxyribonucleic acid (DNA) molecules. There are many small electron-dense granules either surrounding the cell wall or depositing inside the cells. The existence of elements of silver and sulfur in the electron-dense granules and cytoplasm detected by X-ray microanalysis suggested the antibacterial mechanism of silver: DNA lost its replication ability and the protein became inactivated after Ag(+) treatment. The slighter morphological changes of S. aureus compared with E. coli recommended a defense system of S. aureus against the inhibitory effects of Ag(+) ions.

A humanized anti--4-1BB monoclonal antibody suppresses antigen-induced humoral immune response in nonhuman primates

The interaction of 4-1BB and its ligand plays an important role in the regulation of T-cell-mediated immune responses. In this study, the authors examined the effect of a humanized anti--4-1BB monoclonal antibody (H4B4) on ovalbumin-induced immune responses in baboons. Previously, a mouse monoclonal antibody, 4B4 against the human 4-1BB molecule, was generated and characterized. Based on this antibody, a humanized version of 4B4 monoclonal antibody was constructed and the resultant antibody, H4B4, showed full recovery of the binding activity of the original antibody 4B4: a 1.5-fold increase in affinity for 4-1BB. In addition, H4B4 mediated antibody-dependent cellular cytotoxicity of activated human peripheral blood T cells and CEM cells in a dose-dependent manner. Weekly administration of H4B4 at doses of 1 or 4 mg/kg could suppress immunoglobulin G production against ovalbumin. This was not a result of the overall immune suppression, because the numbers of B and T cells and the total immunoglobulin G production were not altered during treatment with H4B4. These findings suggest that treatment with H4B4 may be a valid therapeutic approach to control unwanted immune responses in persons with autoimmune diseases.

A method for determining multileaf collimator transmission and scatter for dynamic intensity modulated radiotherapy

The main purpose of this work is to demonstrate a practical means of determining the leaf transmission and scatter characteristics of a multileaf collimator (MLC) pertinent to the commissioning of dynamic intensity modulated radiotherapy, especially for the sweeping window technique. The data are necessary for the conversion of intensity distributions produced by intensity-modulated radiotherapy optimization systems into trajectories of MLC leaves for dynamic delivery. Measurements are described for two, tungsten alloy MLCs: a Mark II 80-leaf MLC on a Varian 2100C accelerator and a Millenium 120-leaf MLC on a Varian 2100EX accelerator. MLC leakage was measured by film for a series of field sizes. Measured MLC leakage was 1.68% for a 10 x 10 cm2 field for both 6 and 18 MV for the 80-leaf MLC. For the 6 MV field, the 1.68% leakage consisted of 1.48% direct transmission and 0.20% leaf scatter. Direct transmission through the 80-leaf MLC, including the rounded leaf tip, was calculated analytically taking into account the detailed leaf geometry and a Monte Carlo-generated energy spectrum of the accelerator. The integrated fluence under the leaf tip was equivalent to an inward shift of 0.06 cm of a hypothetical leaf with a flat, focused tip. Monte Carlo calculations of the dose to phantom beyond a closed 80-leaf MLC showed excellent agreement with the analytic results. The transmission depends on the density of the MLC alloy, which may differ among individual MLCs. Thus, it is important to measure the transmission of any particular MLC. Calculated doses for a series of uniform fields produced by dynamic sweeping windows of various widths agree with measurements within 2%.

Improvement of oxidative stability of conjugated linoleic acid (CLA) by microencapsulation in cyclodextrins

Oxidative stability of conjugated linoleic acid (CLA) encapsulated in alpha-, beta-, and gamma-cyclodextrins (designated CLA/CDs microencapsules) was studied by measuring the headspace-oxygen depletion in airtight serum bottles and by measuring the peroxide values (POV). The rate of oxygen depletion was reduced from 41.0 (control) to 21.5, 2.1, 1.2, and 1.1 micromol/L.h(-)(1) by CLA/alpha-CD microencapsules at 1:1, 1:2, 1:4, and 1:6 mole ratios, respectively, indicating that CLA oxidation was completely protected by a 1:4 mole ratio of CLA/alpha-CD. Such a protective effect by CLA/beta-CD or CLA/gamma-CD microencapsules was achieved at a 1:6 mole ratio, but the effect by CLA/beta-CD was slightly greater than that by CLA/gamma-CD. The protective effect of alpha-, beta-, and gamma-CDs for CLA oxidation was confirmed by their POV-reducing abilities in CLA/CDs. These results suggest that alpha-CD was the most effective for the protection of CLA oxidation by microencapsulation, followed by beta-CD and gamma-CD.

IL-6 in CSF during ventriculitis in preterm infants with posthemorrhagic hydrocephalus

Treatment of infants with posthemorrhagic hydrocephalus by diversion of CSF is frequently complicated by bacterial ventriculitis. We report the CSF values before and during bacterial ventriculitis of four very low birth weight infants with progressive posthemorrhagic ventricular dilatation. Extremely high CSF IL-6 concentrations of between 8,000 and 61,000 pg/ml were observed and compared with values reported in the literature. IL-6 seems to be a useful marker for bacterial ventriculitis in preterm infants. The role of IL-6 monitoring in the CSF of preterm infants with posthemorrhagic hydrocephalus for early diagnosis of bacterial ventriculitis prior to clinical manifestation should be clarified by further studies.

Cloning and sequencing of cel5Z gene from Erwinia chrysanthemi PY35

The phytopathogenic bacterium Erwinia chrysanthemi (Ech) secretes multiple isozymes of plant cell wall disrupting enzymes such as pectate lyase and endoglucanases. We cloned genomic DNA from Ech PY35 digested with Sau3AI and ligated into pBluescript II SK+. One of the E. coli XL1-blue clones had the ability to hydrolyze carboxymethyl cellulose and polygalacturonic acid. By subsequent subcloning from this 2.9 kb fragment, we obtained a 2.0 kb (pPY401), designated cel5Z, which had the activity of hydrolyzation of carboxymethyl cellulose. The cel5Z gene had an open reading frame (ORF) of 1,281 bp starting with an ATG start codon and followed by a TAA stop codon, encoding 426 amino acids with a signal peptide of 41 amino acids. Since the deduced amino acid sequence of this protein was very similar to that of CelE of Pseudomonas fluorescens, and had the conserved region, VIYEIYNEPL, it belonged to the glycoside hydrolase family 5 of EC 3.2.1.4. The molecular mass of Cel5Z protein from E. coli XL1-blue, as analyzed by CMC-SDS-PAGE, appeared to be 42 kDa. The optimum pH was 6, and the optimum temperature was about 40 degrees C for its enzymatic activity.

Fetal heart rate observations in the brain-damaged infant

The objective of this study was to describe the fetal heart rate patterns and underlying pathophysiologic changes in the brain-damaged fetus. Fetuses with brain damage from hypoxic ischemic encephalopathy do not manifest uniform fetal heart rate patterns. However, these fetuses do show distinct fetal heart rate patterns that permit categorization based on their admission heart rate, subsequent changes in their baseline rate; and neonatal findings. Based on the observations of infants brain damaged in utero because of hypoxic ischemic encephalopathy, the intrapartum fetal management will depend on the admission fetal heart rate pattern, and the subsequent changes in the baseline rate.

Characterization of Erwinia chrysanthemi PY35 cel and pel gene existing in tandem and rapid identification of their gene products

Genomic DNA of the phytopathogenic Erwinia chrysanthemi PY35 was partially digested with Sau3AI, ligated into the BamHI site of pBluescript II SK+, and introduced into E. coli. One clone that was able to hydrolyse carboxymethylcellulose and polygalacturonic acid was selected. A 2.9 kb fragment containing the pelL1 gene (pPY300) and cel5Z gene (pPY401) in tandem was subcloned and sequenced. The pelL1 and cel5Z genes had open reading frames of 1,278 bp and 1,281 bp encoding 425 and 426 amino acid residues with calculated molecular weights of 45,649 Da and 46,473 Da, respectively. pelL1 and cel5Z carried a typical prokaryotic signal peptide of 24 and 41 amino acid residues, respectively. The apparent molecular masses of the proteins when expressed in E. coli cells were approximately 43 kDa (PelL1) and 42 kDa (Cel5Z) as assessed by PGA-SDS-PAGE and CMC-SDS-PAGE.

Mini-detachable snare ligation for the treatment of esophageal varices

BACKGROUND

We manufactured and studied the usefulness of a newly designed mini-detachable snare in the treatment of esophageal varices. The use of a multiple rubber band ligator, although generally effective and well tolerated, has certain limitations, including high cost, reduced visual field, and inadvertent band release.

METHODS

We performed a prospective randomized controlled trial of the use of mini-detachable snare ligation vs. multiple band ligation in patients with recent or active esophageal variceal bleeding. The outcomes assessed were immediate hemostasis and rates of recurrent bleeding, eradication, and recurrence.

RESULTS

From March 1997 to October 1998, 103 patients were entered into this trial; 46 underwent mini-detachable snare ligations and 57 multiple band ligations. Among patients with active bleeding, hemostasis was achieved in 6 of 7 (86%) in the mini-detachable snare ligation group and 11 of 13 (85%) in multiple band ligation group. Recurrent bleeding after initial treatment occurred in 2 of 46 (5.5%) in the mini-detachable snare ligation group and 3 of 57 (5.3%) in the multiple band ligation group. Esophageal varices were eradicated or reduced to grade I in 4.8 +/- 2.1 and 4.5 +/- 1.9 sessions in the mini-detachable snare ligation group and multiple band ligation group, respectively. The recurrence rate was 5 of 46 (11%) and 6 of 57 (11%) in the mini-detachable snare ligation group and multiple band ligation group during a follow-up period of 6 and 16 months, respectively. No serious complication occurred in either group.

CONCLUSION

The mini-detachable snare is a new device that provides safe and effective treatment for esophageal varices that is comparable to multiple band ligation.

Left ventricular muscle mass regression after aortic valve replacement

Implanting a valve that will reduce left ventricular mass is critical in aortic stenosis. Regression of left ventricular hypertrophy in 46 aortic valve replacement (AVR) patients receiving a St. Jude Medical (SJM) valve was assessed by serial electrocardiographic and echocardiographic studies during the preoperative, immediate, and late postoperative periods. The patients were divided into three groups according to valve size; 19 mm group (n=9), 21 mm group (n=20), and 23+mm group (n=17). There was no surgical mortality. The NYHA functional class improved from an average of 2.2+/-0.8 preoperatively to 1.3+/-0.5 post-operatively. Left ventricular muscle mass index (LVMI) regression failed to reach statistical significance in the 19 mm group, whereas in the other two groups a steady decrease in the LVMI occurred with follow up. ECG findings were less remarkable showing insignificant differences in voltage among the three groups (p=0.000). In conclusion, the current data suggest that the 19 mm SJM valve may not result in satisfactory left ventricular muscle mass regression despite adequate function, even in small patients. Therefore, additional procedures to accommodate a larger valve may be warranted in the aortic annulus smaller than 21 mm.

Activation of phonological codes during eye fixations in reading

Two experiments addressed the issue of whether phonological codes are activated early in a fixation during reading using the fast-priming technique (S. C. Sereno & K. Rayner, 1992). Participants read sentences and, at the beginning of the initial fixation in a target location, a priming letter string was displayed, followed by the target word. Phonological priming was assessed by the difference in the gaze duration on the target word between when the prime was a homophone and when it was a control word equated with the homophone on orthographic similarity to the target. Both experiments demonstrated homophonic priming with prime durations of about 35 ms, but only for high-frequency word primes, indicating that lexicality was guiding the speed of the extraction of phonological codes early in a fixation. Evidence was also obtained for orthographic priming, and the data suggest that orthographic and phonological priming effects interact in a mutually facilitating manner.

Activation of phonological codes during eye fixations in reading

Two experiments addressed the issue of whether phonological codes are activated early in a fixation during reading using the fast-priming technique (S. C. Sereno & K. Rayner, 1992). Participants read sentences and, at the beginning of the initial fixation in a target location, a priming letter string was displayed, followed by the target word. Phonological priming was assessed by the difference in the gaze duration on the target word between when the prime was a homophone and when it was a control word equated with the homophone on orthographic similarity to the target. Both experiments demonstrated homophonic priming with prime durations of about 35 ms, but only for high-frequency word primes, indicating that lexicality was guiding the speed of the extraction of phonological codes early in a fixation. Evidence was also obtained for orthographic priming, and the data suggest that orthographic and phonological priming effects interact in a mutually facilitating manner.

Diversity of core promoter mutations in immune clearance phase of chronic HBV infection

BACKGROUND/AIMS

Transcription of HBV (hepatitis B virus) pre-core and pre-genomic mRNAs is controlled by core promoter. Therefore, mutations in the core promoter region might change the activity of liver diseases through an altered transcriptional level of the mRNA. The present study was carried out to determine the diversity of HBV core promoter sequences in chronic HBV carriers.

METHODS

DNA sequences in the core promoter region were determined after cloning the PCR product. Two groups of chronic HBV carriers with HBeAg, including five cases of asymptomatic carriers (ASCs, 21 clones) and eight with chronic hepatitis (CH, 50 clones) were studied.

RESULTS

Mutations in the core promoter were found in three out of the ASCs (11 clones), and in all eight cases in the CH group (48 clones). While mutations at nucleotide 1762 (A-->T) and 1764(G-->A) were not found in ASC, mutations at the same positions were found in all the cases of CH group (40 clones) (P=0.003). Diverse patterns of mutations in the core promoter were observed in each patient in the CH group.

CONCLUSIONS

Further studies are needed to determine whether the diversity of HBV core promoter mutations has clinical significance such as the seroconversion of HBeAg to anti-HBe.