Deeply Virtual Compton Scattering Cross Section at High Bjorken x_{B}

We report high-precision measurements of the deeply virtual Compton scattering (DVCS) cross section at high values of the Bjorken variable x_{B}. DVCS is sensitive to the generalized parton distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton form factors (CFFs) of the nucleon as a function of x_{B}, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs.

Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q^{2}) up to 15.75  (GeV/c)^{2}. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q^{2} and double the range over which a longitudinal or transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q^{2} and attributed to hard two-photon exchange (TPE) effects, extending to 8  (GeV/c)^{2} the range of Q^{2} for which a discrepancy is established at >95% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q^{2}.

Deep Exclusive Electroproduction of π^{0} at High Q^{2} in the Quark Valence Regime

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of x_{B} (0.36, 0.48, and 0.60) and Q^{2} (3.1 to 8.4  GeV^{2}) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions dσ_{T}/dt+εdσ_{L}/dt, dσ_{TT}/dt, dσ_{LT}/dt, and dσ_{LT^{'}}/dt are extracted as a function of the proton momentum transfer t-t_{min}. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross section throughout this kinematic range. The data are well described by calculations based on transversity generalized parton distributions coupled to a helicity flip distribution amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

Measurements of parity-violating asymmetries in electron-deuteron scattering in the nucleon resonance region

We report on parity-violating asymmetries in the nucleon resonance region measured using inclusive inelastic scattering of 5-6 GeV longitudinally polarized electrons off an unpolarized deuterium target. These results are the first parity-violating asymmetry data in the resonance region beyond the Δ(1232). They provide a verification of quark-hadron duality-the equivalence of the quark- and hadron-based pictures of the nucleon-at the (10-15)% level in this electroweak observable, which is dominated by contributions from the nucleon electroweak γZ interference structure functions. In addition, the results provide constraints on nucleon resonance models relevant for calculating background corrections to elastic parity-violating electron scattering measurements.

Measurement of the neutron radius of 208Pb through parity violation in electron scattering

We report the first measurement of the parity-violating asymmetry A(PV) in the elastic scattering of polarized electrons from 208Pb. A(PV) is sensitive to the radius of the neutron distribution (R(n)). The result A(PV)=0.656±0.060(stat)±0.014(syst) ppm corresponds to a difference between the radii of the neutron and proton distributions R(n)-R(p)=0.33(-0.18)(+0.16) fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.

New precision limit on the strange vector form factors of the proton

The parity-violating cross-section asymmetry in the elastic scattering of polarized electrons from unpolarized protons has been measured at a four-momentum transfer squared Q2 = 0.624  GeV2 and beam energy E(b) = 3.48  GeV to be A(PV) = -23.80 ± 0.78(stat) ± 0.36(syst) parts per million. This result is consistent with zero contribution of strange quarks to the combination of electric and magnetic form factors G(E)(s) + 0.517G(M)(s) = 0.003 ± 0.010(stat) ± 0.004(syst) ± 0.009(ff), where the third error is due to the limits of precision on the electromagnetic form factors and radiative corrections. With this measurement, the world data on strange contributions to nucleon form factors are seen to be consistent with zero and not more than a few percent of the proton form factors.

Clinical comparison of high-dose interferon-alpha2b with or without ribavirin for treatment of interferon-relapsed chronic hepatitis C

BACKGROUND

Interferon a with ribavirin combination therapy is effective but still unsatisfactory in the treatment of patients with interferon-relapsed chronic hepatitis C.

AIMS

To compare, in a randomized, double blind, placebo-controlled study, high-dose interferon-alpha2b with or without ribavirin in the treatment for interferon-relapsers.

PATIENTS

A total of 52 patients with interferon-relapsed chronic hepatitis C were randomly assigned to receive 24-week treatment with interferon-alpha2b (6 MU three times per week) combined with either ribavirin (1,000 to 1,200 mg per day) or a matched placebo and then followed for an additional 24 weeks.

METHODS

Hepatitis C virus RNA was detected by reverse-transcription polymerase chain reaction. For determining viral concentration, the commercial bDNA Quantiplex hepatitis C virus-RNA 2.0 assay was used. Genotyping was performed by reverse hybridization assay

RESULTS

At the end of treatment, no detectable hepatitis C virus RNA levels were observed in 92% (24/26) of patients on interferon alpha2b/ribavirin and 81% (21/26) of patients on interferon alpha2b/placebo. At the end of the follow-up, a higher sustained virological response rate was seen in patients treated with interferon alpha2b/ribavirin than those treated with interferon alpha2b/placebo (69% vs 23%, p < 0.001). Patients with either initially high levels of viral concentration or with genotype 1 responded poorly. Patients who received interferon-alpha2b/ribavirin treatment and in whom no hepatitis C virus RNA was detected at 4th week after treatment had 90% chance to achieve sustained virological response.

CONCLUSIONS

High-dose interferon-alpha2b plus ribavirin treatment is highly effective in interferon-relapsed patients.

Limitations and improvements of the quantiplex branched-DNA assay in Hepatitis B virus-infected patients receiving lamivudine

The branched DNA (bDNA) assay for hepatitis B virus (Chiron Corporation Emerville, USA) was investigated by application to HBV-infected patients in Taiwan, where the B and C genotypes of hepatitis B virus are most prevalent. The study group included sera with hepatitis B surface antigen (HBsAg) and e antigen (HBeAg); Group 1 (n=70) without treatment; Group 2 (n=28) lamivudine treatment less than 3 months; Group 3 (n=73) lamivudine treatment 3-12 months; Group 4 (n=45) HBeAg-negative sera after 1 year treatment with lamivudine; control group (n=36) HBsAg-negative sera. Comparison of identical-sample results showed a significantly higher coefficient of variation for low-level HBV DNA (<100 MEq/ml) than for high-level (> or =100 MEq/ml), indicating increasing assay inaccuracy uncertainty as the sample HBV DNA concentration decreased. It is thus concluded that low-titered sera should receive special careful pipetting and processing. It was also found that using the relative luminescence of the negative control plus two standard deviations (S.D.) as a new cutoff could promote sensitivity (97.1-->97.1%, 89.3-->100%, 76.7-->84.9%, and 17.8-->22.2% in Groups 1-4, respectively) and specificity (94.4-->97.2%). In summary, the bDNA HBV assay showed only moderate assay performance for samples with low HBV DNA levels. This problem can be improved partially by choosing a new cutoff value based on the relative luminescence of the negative controls in the kit.

Multiple mucosal lesions in the duodenum: exploring the potential clinical backgrounds and concurrent diseases

BACKGROUND/AIMS

Multiple mucosal lesions of the duodenum (MMLD), presenting with multiple mucosal redness and ulcers with or without blood clots in the proximal duodenum, may be occasionally discovered during gastroduodenal endoscopy. This study was undertaken to investigate the clinical implications of MMLD.

METHODOLOGY

Endoscopic pictures and charts of patients with MMLD were retrospectively reviewed. The endoscopic features of MMLD were recorded for both location and severity. The endoscopic severity of MMLD was defined as follows: Grade I: multiple mucosal redness; Grade II: multiple ulcers with clear base; Grade III: multiple ulcers with reddish base or fresh blood clot coating.

RESULTS

A total of 229 (1.08%) MMLD events in 207 patients were identified out of a total of 21,223 upper gastrointestinal endoscopies. Common backgrounds of patients with MMLD included diabetes, hypertension, and some chemical exposure, such as cigarettes, alcohol, nonsteroidal anti-inflammatory drugs and anti-Helicobacter pyloric regimens. Common concurrent diseases included peptic disease, sepsis, malignancy, renal insufficiency, and portal hypertension. MMLD associated with sepsis usually involved only the second portion of the duodenum, but when associated with nonsteroidal anti-inflammatory drugs was less often only involved with the second portion. MMLD with renal insufficiency was less prone to involve the bulb alone. Diabetes-related MMLD tended to present with mild severity as defined by Grade I, H. pylori infection with Grade II, and renal insufficiency and portal hypertension with higher severity such as Grade III. Nine patients had fatal outcomes due to uncontrolled concurrent diseases, other than MMLD.

CONCLUSIONS

MMLD, an uncommon occurrence in endoscopy, can develop from several clinical settings. When encountering MMLD while performing endoscopy, the best policy is to search and correct the concurrent diseases as early as possible.

Electrochemical therapy--comparison with other local treatment methods on rat model

BACKGROUND/AIMS

Electrochemical therapy is an alternative to treat hepatoma. We compare this method with the other local injection methods on rat liver.

METHODOLOGY

Five groups of Wister rats (24 in each) were anaesthetized. Electrochemical therapy was set under direct current, 6 volts, electrodes were 0.5 cm apart, 0.5 cm deep into exposed parenchyma for 10 min. Local injection was done with 50 microL of 95% alcohol, 30 microL of 20% acetic acid, 30 microL of 35% hydrochloric acid, and 30 microL of 20% sodium hydroxide via a 27-gauge needle under direct vision into each rat. Rats and their livers were examined postmortem on day 1, 3, 7 and 14.

RESULTS

In electrochemical therapy, the treated area showed coagulation necrosis and without blood cells on day 1; then the margin became blurred. Mononuclear cell infiltration, reperfusion and fibrous band formation were prominent from day 3 through day 14. In local injection groups, the necrosis is quite irregular and unpredictable. The regeneration went under similar process.

CONCLUSIONS

To destroy tissue locally, electrochemical therapy is unique for its predictability in destructive area and the recovery process and is as effective as the other injection methods. Therefore, it has great potential for hepatoma treatment.

GB virus-C/hepatitis G virus infection in a hepatitis C virus endemic village: prevalence in residents with low educational attainment and frequent recovery in females

AIMS/BACKGROUND

GB virus-C/hepatitis G virus (HGV) is a newly identified flavivirus, which may share the same mode of transmission as hepatitis C virus (HCV). The aim of this study was to investigate associated factors of HGV infection and clearance in a HCV endemic village in southern Taiwan.

METHODS

Five hundred and ninety-four residents of a village in southern Taiwan were enrolled for hepatitis virus screening. Clinical features were recorded and a questionnaire addressing the possible routes of transmission was filled in by the participating residents.

RESULTS

The prevalence of antibody to hepatitis C virus and hepatitis B surface antigen in the 594 residents was 70.7% and 19.5% respectively. Of the 399 residents tested for HGV RNA, GB virus-C/Hepatitis G virus envelop 2 protein (HGV-E2) antibody, and HCV RNA, the prevalence was 13.5%, 25.3%, 53.1% respectively. Multivariate logistic regression analysis showed that low educational attainment was associated with HGV infection, old age and low educational attainment were associated with HCV infection, and female gender was associated with HGV clearance. Alanine aminotransferase (ALT) values were significantly higher for residents with HCV infection alone, HBV infection alone, and co-infection of HCV and HBV than for those without HBV, HCV, and HGV infection. There were no differences in ALT values between subjects with HGV infection alone and those without HBV, HCV, and HGV infections. Residents with co-infection of HGV and HBV, or HGV and HCV had ALT values similar to those with HBV or HCV infection alone.

CONCLUSION

HGV infection is common in the HCV endemic village. The transmission of HGV is closely related to low educational attainment. HGV clearance is frequently encountered in females. Co-infection of HGV does not compound hepatocellular inflammation.

Saturated saline enhances the effect of electrochemical therapy

We conducted this experiment to assess the effect of saline injection in electrochemical therapy. Platinum electrodes using direct current were inserted into egg white or liver parenchyma. Pure water or 0.9%, 3%, or 26% sodium chloride were injected into various objects to compare with the control group (no injection). Power was set at 10 V. In the egg-white experiment, gas bubbles and coagulated protein developed around the electrodes. In ex vivo liver, frothy reddish debris developed around the cathodes, while a hardening and shrunken surface occurred around the anodes. The pH was 14 around the cathodes, 0 around the anodes. The electric current, the amount of coagulated protein, and the severity of tissue damage were all in proportion to the concentrations of the injected saline. The volume destroyed in the 26% saline group was 8.1 times larger than that of the control group. Therefore, injected saline, especially saturated saline, can enhance the effect of electrochemical therapy.

A three-day course of intravenous omeprazole plus antibiotics for H. pylori-positive bleeding duodenal ulcer

BACKGROUND/AIMS

This prospective trial aimed to test the efficacy of 3-day intravenous omeprazole plus antibiotics for Helicobacter pylori (H. pylori) eradication rate, and to see whether individualized response to omeprazole in intragastric pH elevation will alter the success of eradication.

METHODOLOGY

One hundred and thirty-eight cases with H. pylori-positive duodenal ulcer bleeding were randomized into four therapy groups: Group 1 (n = 32) received a 3-day course of intravenous omeprazole (80 mg loading then 40 mg q 9 am & 9 pm) plus ampicillin/salbactum (1.5 gm i.v. loading then 750 mg q 9 am, 3 pm, & 9 pm); Group 2 (n = 35) followed protocol as for Group 1 except the antibiotics were metronidazole and erythromycin (both 500 mg i.v. q 9 am, 3 pm, & 9 pm). Group 3 (n = 31) followed protocol as for Group 1 and further added with erythromycin (both 500 mg i.v. q 9 am, 3 pm, & 9 pm). Group 4 served as a control group (n = 40) receiving oral dual therapy after leaving the emergency room (omeprazole 20 mg and amoxycillin 1 g bid x 2 weeks). In each case, three gastric biopsies were done for total histologic density of H. pylori (THPD) (range: 0-15) before, 1 day and 6 weeks after completion of therapy. Except for the control group, the 24-hour ambulatory intragastric pH meter (MIC Inc, Gastrograph Spark III, Swiss) was inserted as possible on the 2nd day of therapy.

RESULTS

The 3-day intravenous regimens achieved high clearance rates of H. pylori (Group 1: 93.8%; Group 2: 93.9%; Group 3: 100%). The eradication rates of H. pylori in Groups 1-4 were 43.8%, 57.1%, 58.1%, and 72.8%, respectively. In Groups 1-3, the H. pylori-eradicated cases had lower pre-treatment THPD than non-eradicated cases (6.01 vs. 9.24, p < 0.001). Among 72 cases with pH meter insertion, the percentage of intragastric pH > 5.3 during 24-hour was not different among 35 H. pylori non-eradicated and 37 eradicated cases (78.7 vs. 76.7%, p > 0.05).

CONCLUSIONS

The 3-day intravenous regimens may achieve clearance of H. pylori quickly. However, they were not so effective for eradication, especially in cases with higher bacterial loads. The interindividual response to omeprazole in intragastric pH elevation under the study dosage had insignificant variations to alter the success of eradication.

Liver, spleen and tumor volume measured by personal computer

BACKGROUND/AIMS

Computed tomography (CT) scans are common examinations for patients with chronic liver diseases. To quantitate the organ or tumor volume from the scans and to accomplish the task in an efficient way with the most economic equipment, we developed a system based on a personal computer.

METHODOLOGY

We used color-markers and transparency to sketch the edges of liver, hepatoma, and spleen. Each organ or tumor of interest is marked out by fine-point markers on pieces of transparency. The sketch was scanned into a digitized image format on a personal computer (Pentium 133). The calculation involves edge detection, three-dimensional reconstruction, and voxel counting. By using summation-of-the-area and trapezoid approximation technique, the voxels of each structure are counted. In this study, we illustrate the potential application in the management of a hepatic cancer patient.

RESULTS

After digitalization, the data size of CT images is about 1 to 1.5 megabytes. It takes less than 5 min to complete volume calculation.

CONCLUSIONS

By this method, tumor load before and after chemotherapy can be estimated easily and accurately. This would be helpful in clinical practice.

Long-range effects on the retinal chromophore of bacteriorhodopsin caused by surface carboxyl group modification

Carboxyl groups of bacteriorhodopsin (bR) that are modified by 1-ethyl-3-[3-(trimethylamino)-propyl]carbodiimide (ETC) have been identified. Reaction of deionized purple membrane with a 400-fold molar excess of ETC or [14C]ETC for 1 h at 0 degree C incorporates about 3.5 mol of ETC/mol of bR. Proteinase K cleavage of ETC-modified bacterioopsin (bO) produced small 14C-labeled peptides. Amino acid sequence analysis showed three major ETC-modified residues: Glu 234, Asp 38, and Glu 74. Proteolysis of purple membrane with papain removes the ETC site at Glu 234. Treatment of ETC-modified, papain-cleaved purple membrane with hydroxylamine removes half of the remaining ETC label. Subsequent cleavage with chymotrypsin, followed by amino acid sequence analysis, revealed that most of the remaining label was at Glu 74. bR modified by ETC primarily at Glu 74 displays two alterations in the retinal chromophore, located in the membrane interior at a distance more than 2 nm away from the modified carboxyl group. (1) The acid-induced purple-to-blue transition undergoes a shift in apparent pK from 3.2 to 2.3. (2) The second-order rate constant for chromophore regeneration from bO and retinal is diminished from 3600 to 1700 M-1 s-1 in membrane sheets. Most of the shift in the pK of the purple-to-blue transition can be explained by the quaternary ammonium ion of ETC attached to Glu 74 overlapping the postulated location of the guanidinium group of Arg 82.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors affecting sensitivity of Staphylococcus aureus 196E to polyphosphates

The effect of polyphosphates (eight compounds) on growth of Staphylococcus aureus 196E in brain heart infusion broth was studied. The organism was sensitive (in decreasing order) to chain polyphosphates with 21, 3, 13, and 15 PO4 groups, and bactericidal effects were observed with 0.5% of these compounds. No inhibition was effected by PPi or a metaphosphate. The inhibitory effects were pH dependent, and bacterial sensitivity was highest at pH greater than 7.4. Initial populations affected the number of survivors. No growth was observed after 24 h at 35 degrees C when the initial cell population was less than 10(4) CFU/ml, and a 100- to 1,000-fold decline in cell numbers occurred when initial populations were higher than 10(4) CFU/ml. Sodium tripolyphosphate produced less inhibition after heat sterilization (15 min, 121 degrees C) than after filter sterilization, whereas sodium hexametaphosphate (n = 21) retained most of its antimicrobial activity after heat sterilization. Supplementation of broth with Mg2+ was effective in overcoming inhibition by 0.5% sodium tripolyphosphate, and an addition of 0.25 to 1.0 mM cation restored most of the growth. Inhibition was partially eliminated by Ca2+ and Fe2+, but not by Zn2+ or Mn2+.