Interlayer magnetoresistance of quasi-one-dimensional layered organic conductors

We studied the interlayer magnetoresistance of the representative quasi-one-dimensional (Q1D) layered organic conductor, (TMTSF)2PF6, over the full range of magnetic field orientations in three dimensions, and constructed a stereographic conductivity plot. Our results show that the previously reported angular-dependent magnetoresistance phenomena in Q1D conductors are closely related to one another in intermediate field orientations. Based on a comparison with theories, we can conclude that the Lebed resonance is the only fundamental effect and that other effects result from the modulation of the Lebed resonance amplitude. Most of the observed phenomena can be explained within the framework of the conventional Fermi liquid; however, the anomalous enhancement of the interlayer conductivity under a field parallel to the conducting planes suggests the existence of a new electron state.

Irinotecan monotherapy as second-line treatment in advanced pancreatic cancer

15111

Background: The aim of this phase II study was to determine whether second line therapy with single agent irinotecan could provide any clinical benefit in patients with gemcitabine- pretreated advanced pancreatic cancer. Methods: From January 2004 to October 2006, patients with advanced pancreatic cancer previously treated with gemcitabine alone or combination were treated with single agent irinotecan(150 mg/m2, biweekly), until unacceptable toxicity or disease progression. Primary endpoint was response rate with single stage design. Results: Twenty-eight patients were enrolled(22 male, 6 female, median age : 54.5 years (39–76)). Nine patients are still alive and 3 remain on therapy with stable disease. The median number of cycles was 3.5(1–12). Twenty-four patients were assessable for toxicity and 21 for response. The most common toxicities was diarrhea (grade 3, 12.5%). Grade 3 neutropenia in 1 patient was observed. Other hematological and non-hematological toxicities were mild and manageable. Partial responses were observed in 3 patients (3/21, 14%). An additional 9 patients (9/21, 43%) had stable disease as their best response. 12 patients have progressed with a median time-to-progression of 4.0 months. Conclusions: Single-agent irinotecan was tolerated with manageable toxicity, offering encouraging activity as second-line treatment of patients with advanced pancreatic cancer, refractory to gemcitabine.

No significant financial relationships to disclose.

Sunitinib as second-line treatment for advanced gastric cancer: preliminary results from a phase II study

4603

Background: Sunitinib malate (SU) is an oral, multitargeted tyrosine kinase inhibitor of VEGFRs, PDGFRs, KIT, RET, and FLT3, approved internationally for the treatment of advanced RCC and imatinib-resistant or -intolerant GIST. We investigated the safety and activity of SU monotherapy in pts with previously-treated gastric cancer. Preliminary results from this open-label, multicenter, phase II study are reported. Methods: Eligibility criteria included measurable stage IV disease; 1 prior chemotherapy regimen; and ECOG PS =1. Pts took SU 50 mg/day for 4 wks followed by 2 wks off treatment in 6-wk cycles. A Simon 2-stage design was used with a target accrual of 38 pts in the first stage, expanding to 63 pts if =2 partial responses (PRs) were observed. The primary endpoint was RECIST-defined objective response rate. Secondary endpoints included duration of response and safety. Pharmacokinetic (PK) Ctrough parameters were also monitored. Results: As of Sept 15 2006, 38 evaluable pts (median age 56 years [range 29–78]; 2–3 metastatic sites [63%]; prior treatment with 5-FU ± platinum [P] [24%], capecitabine ± P [13%], TS-1 ± P [26%], other [37%]) have received a median of 2 SU cycles (range 1–3). Of 21 pts evaluable for efficacy, 1 PR has been confirmed and 8 pts had stable disease (SD), 4 with SD for =2 cycles. The most commonly reported AEs were typically grade 1/2 in severity and included stomatitis, skin discoloration, fatigue, anorexia, diarrhea, hand-foot syndrome (HFS), nausea and vomiting. Grade 3/4 toxicities included HFS (10.5%), fatigue (7.9%), anorexia (7.9%) and mucosal inflammation (5.3%). Grade 3/4 hematologic toxicities included neutropenia (29%), thrombocytopenia (29%) and anemia (11%). 7 pts experienced serious SU- related AEs requiring dose modifications in 3 pts and treatment discontinuation in 1 pt. Preliminary PK investigations indicate that concentrations seen in gastric pts are similar to those seen in other pts treated with SU. Conclusions: These initial findings show that SU is generally well tolerated and may have single-agent antitumor activity in pre-treated gastric cancer pts. Further trials with SU in combination with standard chemotherapy regimens are planned.

No significant financial relationships to disclose.

A phase II trial of perioperative chemotherapy with folinic acid, 5-fluorouracil, and oxaliplatin in potentially resectable gastric cancer with regional lymph node metastasis

4602

Background: Peri-operative chemotherapy in operable advanced gastric cancer (AGC) is still in a controversial area. Results from MAGIC trial suggest that a peri-operative regimen of ECF (epirubicin, cisplatin, 5-FU) decreased tumor size and significantly improved PFS and OS in patients with operable AGC (NEJM 355: 11, 2006). The aim of this study was to evaluate the efficacy and toxicity of folinic acid (FA), infusional 5-fluorouracil (5-FU), and oxaliplatin (modified FOLFOX6), administered every 2 wks in potentially operable AGC with regional lymph node (LN) metastasis. Methods: Previously untreated gastric adenocarcinoma patients with measurable LN on CT scan (clinical stage: cT2 or cT3, N+) were eligible. Staging also included a PET-CT and endoscopic ultrasonography (EUS). Patients received 4 cycles of neoadjuvant therapy with FA 100 mg/m2 (2-hr i.v.), 5-FU 2.4 g/m2 (46-hr continuous infusion), and oxaliplatin 100 mg/m2 (2-hr i.v.), followed by curative radical surgery including D2 dissection and 4 cycles of adjuvant modified FOLFOX6. Clinical responses were assessed by RECIST using CT scan before surgery and early metabolic responses were assessed by PET-CT after 2 cycles of chemotherapy. Results: Thirty-one patients were enrolled from Oct. 2004 to Nov. 2006 and currently, 29 of them are evaluable for response. Median age was 56 yrs (range, 35–69). Most patients had EUS T3N1or2 designation. Of 29 evaluable patients, PR were observed in 19 (66%), SD in 9 (31%), and PD in 1 (3%) patient. Early metabolic responses (SUV decrement = 35% by PET-CT) were significantly correlated with conventional radiographic response (p=0.037). The R0 resection rate was 90% and pathologic CR was 7%. Median follow-up duration was 11.8 mo. and median PFS has not been reached yet. Total 219 cycles were administered. G3/4 neutropenia occurred in 6 cycles (3.0%). Nausea G3/4 occurred in 1 cycle (0.5%) and diarrhea in 1 cycle (0.5%). There were no cases of peripheral neuropathy G3/4 or febrile neutropenia G3/4. Conclusions: Peri-operative chemotherapy with modified FOLFOX6 is very effective and feasible in patients with potentially resectable AGC with regional LN metastasis. Early response can be predicted by PET-CT.

No significant financial relationships to disclose.

A randomized multi-center phase II trial of capecitabine (X) versus S-1 (S) as first-line treatment in elderly patients with metastatic or recurrent unresectable gastric cancer

4546

Background: Although the combination chemotherapy is the standard of care for young patients (pts) with advanced gastric cancer (AGC), single agent chemotherapy may be a good alternative for elderly pts. Recent introduction of two new generation oral fluoropyrimidines, capecitabine and S-1, prompted us to investigate the activity and safety of these agents in elderly pts with AGC in a randomized multi-center phase II design. ( NCT00278863 ) Methods: Elderly chemo-naïve pts (= 65 years) with measurable metastatic or recurrent gastric cancer were randomly assigned to receive capecitabine (1,250 mg/m2 bid, D1–14 every 3 weeks, arm X) or S-1 (40∼60 mg bid according to BSA, D1–28 every 6 weeks, arm S). The primary endpoint was the response rate (RR). Results: From Oct 2004 to Apr 2006, 96 pts were enrolled. Excluding 5 pts who did not fit inclusion criteria, 91 pts were randomized to arm X (N=46) or arm S (N=45). Median age was 70.5 years for arm S and 71.0 years for arm X. Other clinical and tumor characteristics were well balanced across the two treatment arms. Among 44 assessable pts in arm X, 13 attained partial response (PR, 29.5%), 17 stable disease (SD, 38.6%) and 10 progressive disease (PD); 4 pts were not evaluable (NE). The corresponding disease responses in the 45 assessable pts in arm S were: 1 complete response (2.2%), 12 PR (26.7%), 18 SD (40.0%), 10 PD, and 4 NE. The incidence of grade 3–4 granulocytopenia was 6.8% in arm X and 4.8% in arm S. One episode of febrile neutropenia was observed in arm X. Grade 3–4 non-hematologic toxicities were as follows (arm X vs. S): asthenia (0% vs. 7.2%), anorexia (6.8% vs. 9.5%), diarrhea (2.3% vs. 0%), and HFS (6.8% vs. 0%). With a median follow up of 13.5 months (mo) for survivors (range, 8.1∼21.9), median time to progression and time to treatment failure were 4.8 mo (95% CI, 3.0–6.5) and 4.4 mo (3.6–5.3) for arm X and 4.2 mo (1.5–6.9) and 3.0 mo (1.5–4.5) for arm S. Median overall survival was 10.0 mo (8.0–12.0) for arm X and 7.9 mo (4.1–11.7) for arm S. Conclusions: Both treatments were active and tolerable as a 1st line treatment for elderly pts with AGC.

No significant financial relationships to disclose.

Comparison of the epidermal growth factor receptor gene mutation in matched primary tumor and lymph node metastasis of non-small cell lung cancer

7614

Background: Mutations in epidermal growth factor receptor (EGFR) are considered as a strong predictive marker to EGFR tyrosine kinase inhibitors (TKIs) in non-small-cell lung cancer (NSCLC). Recent studies suggested EGFR status may change between primary NSCLC and corresponding metastatic site. However, it has not fully been evaluated whether EGFR mutation differs in metastases compared to primary NSCLC. Methods: In total, 128 tumor samples from 64 NSCLC patients were investigated comparing matched 64 primary tumors, and 64 lymph node metastases. The epidermal growth factor receptor mutation status was analyzed by a direct sequencing method (exons 18–21 in EGFR) on tumor samples of primary NSCLC and corresponding lymph node metastasis. Results: In 17.2% of patents (11/64), EGFR mutation was identified in either primary NSCLC or metastasis by DNA sequencing. Six (54.5%) out of eleven cases showed discordance of EGFR mutation in the primary tumor/metastasis site. Two cases showed EGFR mutation in the metastasis but not in the primary tumor, while, in four cases, EGFR mutation was detected in the primary tumor but not in the metastasis site. The majority of discordance of EGFR mutations was identified in exon 19 (83.3%, 5/6). The median overall survival (OS) was 17.7 months (95% confidence interval, 9.4–20.0). Median OS was not varied by the discordance of EGFR mutation status between primary NSCLC and corresponding metastatic site. Conclusions: The status of EGFR mutation in primary NSCLC and that in corresponding metastasis site varied in considerable cases by DNA sequencing. Whether the status of EGFR mutation changes during the process of metastasis remains to be evaluated. Future study to evaluate the correlation of tumour response to TKIs and the discordance of the EGFR mutation status is warranted.

No significant financial relationships to disclose.

Pharmacokinetic and pharmacodynamic modelling of the effects of glimepiride on insulin secretion and glucose lowering in healthy humans

Glimepiride is an oral sulfonylurea antihyperglycaemic agent. We used pharmacokinetic-pharmacodynamic (PK-PD) modelling to analyse the relationship between plasma glimepiride concentration, insulin secretion and glucose lowering to determine the effects of the drug in healthy volunteers. A single 2-mg oral dose of glimepiride was administered to six healthy volunteers. The control group received a placebo. All subjects consumed 12 g of sugar immediately after drug administration in order to standardize the initial plasma glucose levels. Serial blood sampling was performed for 9 h after oral dosing. Plasma glimepiride, insulin and glucose levels were determined by validated methods (LC/MS/MS assay, hexokinase method and radioimmunoassay respectively). Time courses of plasma glimepiride concentration, insulin secretion, and glucose lowering effects were analysed by means of PK-PD modelling with the ADAPT II program. The time course of the plasma concentrations followed a two-compartmental model with a lag time. The glimepiride concentration peaked at 191.5 ng/mL at approximately 4 h after administration. The maximal increase in insulin secretion was 9.98 mIU/L and the maximal decrease in plasma glucose was 19.33 mg/dL. Both peak effects occurred at approximately 2.5 h after drug intake. The glucose disappearance model was used to analyse glimepiride's insulin secretion and glucose lowering effects. The PK-PD model described well the relationship between plasma glimepiride and its insulin secretion and hypoglycaemic effects in healthy volunteers.

A phase II study of irinotecan, oxaliplatin, 5-fluorouracil, leucovorin (FOLFOXIRI) as a first-line chemotherapy in metastatic gastric cancer

4076

Background: Previous phase II study showed a high efficacy and safety of FOLFOXIRI (irinotecan, oxaliplatin, 5-fluorouracil, leucovorin) combination chemotherapy in metastatic colorectal cancer. This non-randomized open label phase II study evaluated the efficacy and safety of FOLFOXIRI in metastatic or recurrent gastric cancer patients. Methods: Patients with: histologically proven, bidimensionally measurable, metastatic gastric adenocarcinoma, age 18 - 70 years, with a performance status 0 - 2, no prior chemotherapy or at least 12 months after adjuvant therapy, life expectancy > 3 months, signed written informed consent were eligible. Treatment consisted of irinotecan 150 mg/m2 day 1, oxaliplatin 85 mg/m2 day 1, leucovorin 100 mg/m2 day and 5-fluorouracil 2000 mg/m2 as a 48-h continuous infusion starting on day 1, repeated every 2 weeks until unacceptable toxicity, patients’ refusal, or up to 12 cycles. The planned sample size was 48 and the primary endpoint was response rate. Results: From August 2004 to August 2005, 48 patients were prospectively enrolled. The median age was 54 years (24 - 69) and male:female ratio was 1.3:1. In total, 379 cycles were administered with a median of 9 cycles per patient (range, 1–12) and 45/48 patients were evaluable for treatment response. Three patients were not assessable for response due patients’ refusal for further chemotherapy following the first cycle. By per-protocol analysis, the objective response rate was 73.3 % (95% CI, 60.8–85.8) with 2 CRs and 31 PRs. Four patients (9%) had stable disease and 8 patients (18%) had progressive disease. The estimated median survival of all patients was 14.0 months (95% CI, 11.8 - 16.2 ) and the estimated median time-to-progression was 8.9 months (95% CI, 6.7–11.0). In total of 379 cycles administered, most common grade 3/4 toxicities were neutropenia (11% of all cycles) and emesis (12%). Grade 2 peripheral neuropathy occurred in 5 patients. One (2%) patient had severe tumor bleeding and 5 (10%) patients experienced grade 3 diarrhea. Conclusions: FOLFOXIRI combination chemotherapy showed a very promising preliminary anti-tumor activity and was generally well tolerated as a first-line treatment for patients with metastatic gastric cancer.

No significant financial relationships to disclose.

A multicenter phase II study of pemetrexed and cisplatin in patients with advanced gastric cancer (AGC)

14008

Background: Pemetrexed is a novel folate antimetabolite, and it inhibits a number of folate-dependent enzymes. This agent has demonstrated activity in a variety of tumor types including AGC. This study was performed to evaluate the combination of pemetrexed and cisplatin in the treatment of AGC. The primary endpoint was response rate, and secondary endpoints were duration of response, time to progressive disease, time to treatment failure, overall survival, and toxicity. Methods: Patients with stage IV AGC not to be amendable to curative surgery and measurable disease were eligible. Pemetrexed 500 mg/m2 and cisplatin 75 mg/m2 were given on day 1, every 21 days. Treatment was supplemented with folic acid, vitamin B12, and dexamethasone. Response was assessed by RECIST, and toxicity was assessed by NCI-CTC v 2.0. Results: From October 2003 to September 2004, 51 patients were enrolled, but 1 did not meet the eligibility criteria. There were 37 men and 13 women with a median age of 56 years (range, 24–69) and an ECOG PS 0/1 for 14/36 patients; all had metastatic disease. Of 50 evaluable patients, there were no complete responses, and 13 had confirmed partial responses (26%; 95% CI, 14.6%-40.3%). Fifteen patients (30%) had stable disease, and 21 (42%) progressed, and 1 (2%) was unknown. Among 13 responders, the median durarion of response was 3.60 months (95% CI, 2.80–9.40). Median time to progressive disease was 2.8 months (95% CI, 2.20–4.40), and median overall survival was 6.6 months (95% CI, 4.80–10.40). The median time to treatment failure was 2.10 months (95% CI, 1.00–2.80). Survival estimates were 32.0% at 3 months and 7.0% at 6 months. A total of 212 cycles were administered to 51 patients (median 4 [range, 1–13]). Based on 51 patients, most common grade 3/4 hematologic toxicities were neutropenia (49.0%), leukopenia (19.7%), and anemia (13.7%); the most common grade 3/4 nonhematologic toxicities were hyponatremia (15.7%), anorexia (9.8%), nausea (7.8%), and vomiting (7.8%). Conclusions: : The combination of pemetrexed and cisplatin in the current dose and schedule has a modest activity and a mild toxicity profile in patients with AGC. Further study is warranted using a different dose and treatment schedule.

[Table: see text]

Interaction effects and pseudogap in two-dimensional lateral tunnel junctions

Tunneling characteristics of a two-dimensional lateral tunnel junction are reported. A pseudogap on the order of Coulomb energy is detected in the tunneling density of states (TDOS) when two identical two-dimensional electron systems are laterally separated by a thin energy barrier. The Coulombic pseudogap remains robust well into the quantum Hall regime until it is overshadowed by the cyclotron gap in the TDOS. The pseudogap is modified by the in-plane magnetic field, demonstrating a nontrivial effect of the in-plane magnetic field on the electron-electron interaction.

Pharmacokinetics and pharmacodynamics of benidipine using a slow receptor-binding model

PURPOSE

This study examined the relationship between the plasma concentration of benidipine, a long-lasting antihypertensive agent with Ca(2+)-channel-blocking properties, and its cardiovascular effects (reduction in blood pressure and increase in heart rate) in order to assess the usefulness of pharmacokinetic-pharmacodynamic (PK-PD) modelling in describing this relationship.

METHODS

Two groups of 24 healthy volunteers received either a 4- or 8-mg benidipine hydrochloride tablet; 11 additional subjects received a placebo. Serial blood sampling and PD measurements were performed over 8 h thereafter. Plasma concentrations of benidipine were measured with a validated LC/MS/MS system, and the effects on blood pressure and heart rate were assessed during the same period. A two-compartment open model with lag time was used to explain the PK properties, and the PD model was characterized by slow receptor binding, reflecting the binding of benidipine to the ion-channel receptor.

RESULTS

Benidipine reached mean peak plasma concentrations of 1.04 and 3.85 ng/mL at 0.5 and 0.75 h after 4 and 8 mg doses, respectively. Peak cardiovascular effects were detected approximately 2 h after the administration of either dose. Maximal decreases in diastolic blood pressure with 4 and 8 mg of benidipine were 7.79 and 14.75 mmHg, respectively, and maximal increases in heart rate were 7.32 and 17.56 bpm, respectively. No significant changes in systolic blood pressure were observed. The cardiovascular effects were analysed according to a slow receptor-binding model.

CONCLUSIONS

The tested PK-PD model successfully described the relationship between the plasma concentration of benidipine and its cardiovascular effects.

Resonant nernst effect in the metallic and field-induced spin density wave States of (TMTSF)2ClO4

We examine an unusual phenomenon where, in tilted magnetic fields near magic angles parallel to crystallographic planes, a "giant" resonant Nernst signal has been observed by Wu et al. [Phys. Rev. Lett. 91, 056601 (2003)] in the metallic state of an organic conducting Bechgaard salt. We show that this effect appears to be a general feature of these materials and is also present in the field-induced spin density wave phase with even larger amplitude. Our results place conditions on any model that treats the metallic state as a state with finite Cooper pairing.

77Se NMR probe of magnetic excitations of the magic angle effect in (TMTSF)2PF6

We report 77Se spin-lattice relaxation rates for (TMTSF)2PF6, carried out in the regime where a set of spectacular transport anomalies known as the "magic angle effects" are observed. In situ resistance measurements (R(zz)) were used to verify the experimental conditions and give precise sample alignment information. We found that the 77Se T-11 exhibits no significant changes as the magnetic-field orientation is rotated through the magic angles, and conclude that there is no evidence for either a single-particle gap or a spin gap. The clearly observed field-induced spin-density wave transition temperature is also, unexpectedly, not enhanced at the magic angles.

Implant contraception in Singaporean women: one decade of experience in KK Women's and Children's Hospital

INTRODUCTION

The aim of this study was to assess user acceptability and effectiveness of implant contraception in Singaporean women.

METHODS

A prospective study was carried out on 553 patients who received Norplant implant in our hospital from 1 January 1992 to 31 December 2000, and followed-up till 15 July 2003. The patients' profile, side-effects, satisfaction and continuation rate of Norplant implant were studied.

RESULTS

The mean age of the subjects was 29.4 (plus or minus 5.1) years. The mean parity was 2.1 (plus or minus 1) live births. More than one-half (55.2 percent) of the subjects had used other methods of contraception before. The main reason for them to switch to implant contraception was convenience (63.6 percent). Of the 516 users on follow-up, the common side-effects were menstrual irregularity (51 percent), secondary amenorrhoea (9.6 percent) and weight gain (15.7 percent). 29.3 percent of users did not experience any side-effect. There was only one contraceptive failure, which may be related to drug interaction. The Pearl Index was 0.054 per hundred women years. There was only one serious adverse event of a patient (0.2 percent) who developed severe hypertension requiring treatment. The continuation rate was 92.4 percent after one year, 80.8 percent after two years, 68.9 percent after three years and 58.5 percent after four years. The main reasons for early implant removal were side-effects and desire for future pregnancy. Re-insertion was carried out in 53.7 percent of users who had completed five years of Norplant contraception.

CONCLUSION

This largest sub-dermal hormonal implant contraception study in multi-racial Singapore showed that Norplant contraception had a high degree of effectiveness with relatively high user satisfaction and continuation rate.

Cascade of quantum phase transitions in tunnel-coupled edge states

We report on the cascade of quantum phase transitions exhibited by tunnel-coupled edge states across a quantum Hall line junction. We identify a series of quantum critical points between successive strong and weak tunneling regimes in the zero-bias conductance. Scaling analysis shows that the conductance near the critical magnetic fields B(c) is a function of a single scaling argument /B-B(c)/T(-kappa), where the exponent kappa=0.42. This puzzling resemblance to a quantum Hall-insulator transition points to the importance of interedge correlation between the coupled edge states.

The scavenger receptor, cysteine-rich domain-containing molecule gp-340 is differentially regulated in epithelial cell lines by phorbol ester

Gp-340 is a glycoprotein belonging to the scavenger receptor cysteine rich (SRCR) group B family. It binds to host immune components such as lung surfactant protein D (SP-D). Recent studies found that gp-340 interacts directly with pathogenic microorganisms and induces their aggregation, suggesting its involvement in innate immunity. In order to investigate further its potential immune functions in the appropriate cell lines, the expression of gp-340 in four conventional immune cell lines (U937, HL60, Jurkat, Raji), and two innate immune-related epithelial cell lines (A549 derived from lung and AGS from stomach), was examined by RT-PCR and immunohistochemistry. The resting immune cell lines showed weak or no gp-340 mRNA expression; while the two epithelial cell lines expressed gp-340 at much higher level, which was differentially regulated by phorbol myristate acetate (PMA) treatment. In the A549 cells, gp-340 was up-regulated along with the PMA-induced proinflammatory expression of both IL-6 and IL-8. In AGS cells, PMA down-regulation of gp-340 was seen in parallel with an up-regulation of the two mature gastric epithelial specific proteins TFF1 (trefoil factor 1) and TFF2, which are implicated as markers of terminal differentiation. Analysis of the distribution of gp-340, together with the TFFs and SP-D in normal lung and gastric mucosa, supported further our in vitro data. We conclude that the differential regulation of gp-340 in the two epithelial cell lines by PMA indicates that gp-340 s involvement in mucosal defence and growth of epithelial cells may vary at different body locations and during different stages of epithelial differentiation.

Accuracy of CT in local staging of gallbladder carcinoma

PURPOSE

To evaluate the accuracy of CT for staging gallbladder cancers, especially the T-factor of the TNM staging system.

MATERIAL AND METHODS

CT investigations of 100 patients with surgically proven gallbladder cancers were retrospectively analyzed. Dynamic helical CT was performed in 16 patients and conventional CT in the remaining 84. On CT, three radiologists attempted tumor staging for these patients; the majority opinion was used for final decision. According to CT protocols (dynamic helical CT vs. conventional CT) and each tumor type (thickened wall/intraluminal mass/massive), the accuracy of CT staging was compared. The CT staging was correlated with the surgico-pathologic results.

RESULTS

The overall accuracy of CT for staging gallbladder cancers was 71%; it was 79% for T1 and T2 tumors, 46% for T3 tumors, and 73% for T4 tumors. For all three readers, the poorest accuracy was obtained in T3 tumors. No statistically significant difference was noted in the accuracy between the groups undergoing conventional CT and dynamic helical CT. A statistically significant difference was noted in the accuracy for staging thickened wall and intraluminal mass types of tumors (p<0.05); the highest accuracy was obtained in the intraluminal mass type (89%) and the massive type (83%), while it was 54% in the thickened wall type.

CONCLUSION

The accuracy of tumor staging with CT in patients with gallbladder cancer depends on the morphological type of tumor. The poorest result is obtained in the thickened wall type.

Triplet superconductivity in an organic superconductor probed by NMR Knight shift

The nature of the superconducting state in quasi-one-dimensional organic conductors has remained controversial since its discovery. Here we present results of (77)Se NMR Knight shift (K(s)) experiments in (TMTSF)(2)PF(6) under 7 kbar of pressure with a magnetic field aligned along the most conducting a axis. We find no noticeable shift in K(s) upon cooling through the superconducting transition. Since K(s) directly probes the spin susceptibility chi(s), the fact that chi(s) remains unchanged through the superconducting transition strongly suggests spin-triplet superconductivity.

Evolutionary relationships and systematics of the alphaviruses

Partial E1 envelope glycoprotein gene sequences and complete structural polyprotein sequences were used to compare divergence and construct phylogenetic trees for the genus Alphavirus. Tree topologies indicated that the mosquito-borne alphaviruses could have arisen in either the Old or the New World, with at least two transoceanic introductions to account for their current distribution. The time frame for alphavirus diversification could not be estimated because maximum-likelihood analyses indicated that the nucleotide substitution rate varies considerably across sites within the genome. While most trees showed evolutionary relationships consistent with current antigenic complexes and species, several changes to the current classification are proposed. The recently identified fish alphaviruses salmon pancreas disease virus and sleeping disease virus appear to be variants or subtypes of a new alphavirus species. Southern elephant seal virus is also a new alphavirus distantly related to all of the others analyzed. Tonate virus and Venezuelan equine encephalitis virus strain 78V3531 also appear to be distinct alphavirus species based on genetic, antigenic, and ecological criteria. Trocara virus, isolated from mosquitoes in Brazil and Peru, also represents a new species and probably a new alphavirus complex.

Effects of tyrosine kinase signaling inhibition on survival after cecal ligation and puncture in diet-restricted mice

BACKGROUND

Malnutrition impairs host immunity, resulting in high mortality and morbidity due to infections. Phosphorylation of protein tyrosine kinase (PTK) is a key step in the signaling of many cellular functions, including immune cell functions. Malnutrition may affect this signaling in response to surgical insults. The aim of this study was to examine the effects of PTK inhibition on mortality in ad libitum and in diet-restricted mice after cecal ligation and puncture (CLP). Moreover, tyrosine phosphorylation of peritoneal cells from these animals was evaluated.

METHODS

Survival study: Mice (n = 45) received chow, 146 g/kg per day (ad libitum) or 36.5 g/kg per day (diet-restricted), for 7 days. Two hours before CLP, one-half the mice in each group were given a tyrosine kinase inhibitor, AG 556 (3.0 mg/kg i.p.), and the others received vehicle. Survival was observed up to 7 days after CLP. Effects of AG 556 on survival with a lesser degree of malnutrition (chow 73 g/kg per day) were also examined (n = 41). Measurement of tyrosine phosphorylation: mice (n = 20) were assigned to the ad libitum and diet-restricted (chow 36.5 g/kg per day) groups. Peritoneal cells were harvested either before or 2 hours after glycogen injection. Glycogen treatment elicits polymorphonuclear neutrophil influx into the peritoneal cavity. The cells were incubated with or without N-formyl-methionyl-leucyl-phenylalanine (fMLP). Tyrosine phosphorylation in the cells was examined using flow cytometry, laser scanning cytometry, and Western blotting.

RESULTS

Diet restriction significantly reduced survival compared with the ad libitum group. AG 556 treatment decreased the survival of ad libitum, but not in diet-restricted mice in both survival experiments. Stimulation of peritoneal cells with fMLP increased tyrosine phosphorylation in the ad libitum group (23% increase before glycogen and 18% after glycogen), but not in the diet-restricted group (-9% before glycogen and 3% after glycogen).

CONCLUSIONS

Inhibition of tyrosine kinase signaling impairs the ability of a well-nourished host to survive CLP-induced sepsis, while having no effects on survival in diet-restricted mice. Peritoneal cells from diet-restricted animals are unable to increase PTK phosphorylation in response to stimulation, which may be the mechanism underlying impaired host defense during malnutrition.

Influence of P-glycoprotein modulators on cardiac uptake, metabolism, and effects of idarubicin

PURPOSE

The clinical utility of anthracyclines like idarubicin (IDA) is limited by the occurrence of multidrug resistance and cardiotoxicity. Previous studies have demonstrated that the multidrug transporter P-glycoprotein (P-gp) is present in the heart and have suggested that it exerts a protective function. We sought to determine the influence of P-gp inhibitors verapamil and PSC 833 on myocardial uptake, metabolism, and actions of IDA.

METHODS

In Langendorff-perfused rat hearts, the outflow concentration-time curve and the residual amount in cardiac tissue of IDA and its active metabolite idarubicinol (IDOL) were measured after 0.5 mg dose of IDA in the absence and presence of the P-gp inhibitors verapamil and PSC 833.

RESULTS

During perfusion (80 min), 2% of the IDA dose was converted to IDOL in the heart. Myocardial uptake of IDA was significantly increased by verapamil but not by PSC 833, which increased the recovery of IDA and IDOL. IDA significantly decreased left ventricular developed pressure to approximately 40% and increased coronary vascular resistance to 140% of baseline level, respectively. The vasoconstrictive effect was markedly potentiated by PSC 833.

CONCLUSIONS

The enhancement of myocardial IDA uptake by verapamil could be due to a decrease in P-gp-mediated efflux. PSC 833 inhibits cardiac metabolism (non-IDOL pathways) and increases the acute cardiotoxicity of IDA.

Thermodynamic second law in irreversible processes of chaotic few-body systems

Irreversible processes of few hard-ball (N) mechanical systems are investigated numerically and compared with the theoretical results of quasistatic processes. The thermodynamic second law is valid for N>or=2 for both equilibrium and nonequilibrium systems if the average ensemble of the large number of identical systems is taken.

Study of retinal nerve fibre layer thickness in eyes with high tension glaucoma and hemifield defect

AIM

To quantitatively evaluate retinal nerve fibre layer (RNFL) difference in areas of apparently normal appearing visual field in eyes with high tension glaucoma (HTG) and hemifield defects using scanning laser polarimetry.

METHODS

40 eyes from 40 patients with HTG with superior or inferior hemifield defects based on the Humphrey field analyser (HFA) underwent RNFL thickness measurements. 20 normal eyes from 20 subjects matched in age and refractive error were selected as a control group. The RNFL thickness was measured with a scanning laser polarimeter. Mean RNFL thickness was evaluated in four quadrants (superior, inferior, nasal, and temporal). A superior or inferior quadrant in the defined ring of scanning laser polarimetry corresponds to inferior or superior hemifield in HFA.

RESULTS

The mean RNFL thickness in the unaffected quadrant (the quadrant corresponding to the hemifield with apparently normal visual field based on HFA) of the HTG group was significantly thinner than the average RNFL thickness of the corresponding quadrant of the control eyes. The RNFL thickness of the unaffected quadrant in the eyes with HTG was reduced and statistically similar to that of the affected quadrant. Symmetry, calculated as the ratio of superior to inferior RNFL thickness, showed no statistical difference between the study and control group.

CONCLUSION

Changes in RNFL are present in the apparently normal hemifield in the eyes with HTG. The thickness of the RNFL is reduced symmetrically in both superior and inferior quadrants based on the GDx parameters.

Development of expression systems for the production of recombinant human serum albumin using the MOX promoter in Hansenula polymorpha DL-1

To optimize the secretory expression of recombinant human serum albumin (HSA) under the control of methanol oxidase (MOX) promoter in the methylotrophic yeast Hansenula polymorpha DL-1, we analyzed several parameters affecting the expression of HSA from the MOX promoter. Removal of the 5'-untranslated region derived from HSA cDNA in the expression cassette led to at least a fivefold improvement of HSA expression efficiency at the translational level. With the optimized expression cassette, the gene dosage effect on HSA expression was abolished and thus, a single copy of the expression vector integrated into the MOX locus became sufficient for the maximal expression of HSA. Northern blot analysis revealed that the levels of HSA transcript did not increase any further upon increasing copy number. The mox-disrupted (mox Delta) transformant was constructed, in which the genomic MOX gene was transplaced with the HSA expression cassette, to examine the effect of the methanol oxidase-deficient phenotype of the host on HSA expression. The mox Delta transformant showed higher levels of HSA production in shake-flask cultures than the MOX wild-type transformant, especially at low concentrations of methanol and a twofold higher specific HSA production rate in fed-batch fermentation with an abrupt induction mode. The native prepro signal sequence of HSA secreted in H. polymorpha was correctly processed and the mature recombinant protein had a pI value identical to that of the authentic HSA. Our results suggest that the H. polymorpha expression systems developed in this study are suitable for large-scale production of recombinant albumin.

Virulence and viremia characteristics of 1992 epizootic subtype IC Venezuelan equine encephalitis viruses and closely related enzootic subtype ID strains

Following a 19-year hiatus, Venezuelan equine encephalitis (VEE) reemerged in western Venezuela in December 1992. This outbreak is important in understanding VEE emergence because phylogenetic studies imply that sympatric, enzootic, subtype ID VEE viruses mutated to generate the epizootic/epidemic. Although the 1992-1993 strains belong to subtype IC, a serotype implicated in extensive outbreaks during the 1960s and in 1995, relatively small numbers of human and equine cases occurred in 1992-1993. We, therefore, evaluated the pathogenicity of these Venezuelan enzootic ID and epizootic IC viruses to determine 1) if they exhibit phenotypes like those described previously for more distantly related enzootic and epizootic strains, and 2) if the 1992-1993 outbreak was limited by the inability of these IC viruses to exploit equines as amplification hosts. All strains were virulent in mice and guinea pigs, but were benign for cotton rats, natural hosts of enzootic viruses. However, only the IC strains produced equine disease, with mean peak viremias of 10(5) suckling mouse 50% lethal doses per mL serum, and some titers exceeding 10(7). These viremias approximate those observed previously with VEE strains isolated during more extensive epizootics, suggesting that efficient equine amplification did not limit the scope and duration of the 1992-1993 outbreak. Enzootic ID virus infection protected all horses from challenge with epizootic strain P676, supporting the hypothesis that epizootics bypass regions of enzootic transmission due to natural immunization of equines by enzootic VEE viruses.

Potential sources of the 1995 Venezuelan equine encephalitis subtype IC epidemic

Venezuelan equine encephalitis viruses (VEEV) belonging to subtype IC have caused three (1962-1964, 1992-1993 and 1995) major equine epizootics and epidemics. Previous sequence analyses of a portion of the envelope glycoprotein gene demonstrated a high degree of conservation among isolates from the 1962-1964 and the 1995 outbreaks, as well as a 1983 interepizootic mosquito isolate from Panaquire, Venezuela. However, unlike subtype IAB VEEV that were used to prepare inactivated vaccines that probably initiated several outbreaks, subtype IC viruses have not been used for vaccine production and their conservation cannot be explained in this way. To characterize further subtype IC VEEV conservation and to evaluate potential sources of the 1995 outbreak, we sequenced the complete genomes of three isolates from the 1962-1964 outbreak, the 1983 Panaquire interepizootic isolate, and two isolates from 1995. The sequence of the Panaquire isolate, and that of virus isolated from a mouse brain antigen prepared from subtype IC strain P676 and used in the same laboratory, suggested that the Panaquire isolate represents a laboratory contaminant. Some authentic epizootic IC strains isolated 32 years apart showed a greater degree of sequence identity than did isolates from the same (1962-1964 or 1995) outbreak. If these viruses were circulating and replicating between 1964 and 1995, their rate of sequence evolution was at least 10-fold lower than that estimated during outbreaks or that of closely related enzootic VEEV strains that circulate continuously. Current understanding of alphavirus evolution is inconsistent with this conservation. This subtype IC VEEV conservation, combined with phylogenetic relationships, suggests the possibility that the 1995 outbreak was initiated by a laboratory strain.

Extreme genetic diversity among Pirital virus (Arenaviridae) isolates from western Venezuela

Pirital-like virus isolates from rodents collected in a variety of habitats within a six-state area of central Venezuela were analyzed genetically by amplifying a portion of the nucleocapsid protein gene using RT-PCR. Comparisons of the sequences from 30 selected Pirital-like virus isolates demonstrated up to 26% divergence in nucleotide sequences and up to 16% divergence in deduced amino acid sequences. Within the Pirital monophyletic group, 14 distinct lineages or genotypes, differing by at least 6% in nucleotide sequences, were identified. Although sample sizes were small for some lineages, many of the different genotypes were sampled in only one region or locality, suggesting allopatric divergence. Complement fixation tests with representatives of the most divergent Pirital virus lineages failed to delineate multiple species or subtypes within the Pirital clade. These results indicate that the previously proposed 12% nucleocapsid protein amino acid sequence divergence cutoff value for delineating arenavirus species is not appropriate for the entire family. When individual clones were examined from PCR amplicons, a mean of 0.17% sequence diversity vs the consensus sequences was detected, suggesting diverse quasispecies populations within infected rodent hosts. Possible explanations for the extreme genetic diversity within and among Pirital virus populations in infected rodents are discussed.

Supranormal differential renal function is real but may be pathological: assessment by 99m technetium mercaptoacetyltriglycine renal scan of congenital unilateral hydronephrosis

PURPOSE

It is unclear whether supranormal differential renal function of the hydronephrotic kidney is real or artifactual. We investigated the effect of clinical and renographic parameters on differential renal function.

MATERIALS AND METHODS

The study included 34 males and 10 females from 1 to 9 months old (median age 2.6 months) with unilateral congenital hydronephrosis. A 99mtechnetium (Tc) mercaptoacetyltriglycine (MAG3) scan was performed, and regions of interest were drawn on the kidneys, and perirenal and lateral backgrounds. Differential renal function was calculated with and without background subtraction at 30-second intervals from 0.5 to 3 minutes after injection of 99mTc-MAG3. The effects of age, sex, obstruction, site and size of the hydronephrotic kidney were analyzed using the generalized estimating equations method.

RESULTS

There were 11 right and 33 left hydronephrotic kidneys. An obstructive renographic pattern was present in 33 cases. The trends of differential renal function according to intervals were different between kidneys with and without background subtraction, and differential renal function increased significantly as size increased (p <0.05). Differential renal function of the hydronephrotic kidney with an obstructive renographic pattern increased with time when perirenal or no background subtraction was applied (p <0.05). The effects of age, sex or laterality on differential renal function were not significant. Supranormal function (differential renal function 55% or greater) was present regardless of background subtraction methods and measurement time.

CONCLUSIONS

Differential renal function is higher in larger hydronephrotic kidney but function of the kidney with an obstructive pattern is overestimated on later phases of 99mTc-MAG3 renal scan. Supranormal differential renal function is real and may be pathologic since it is prone to occur in larger obstructive hydronephrotic kidneys.

Supranormal differential renal function is real but may be pathological: assessment by 99m technetium mercaptoacetyltriglycine renal scan of congenital unilateral hydronephrosis

PURPOSE

It is unclear whether supranormal differential renal function of the hydronephrotic kidney is real or artifactual. We investigated the effect of clinical and renographic parameters on differential renal function.

MATERIALS AND METHODS

The study included 34 males and 10 females from 1 to 9 months old (median age 2.6 months) with unilateral congenital hydronephrosis. A 99mtechnetium (Tc) mercaptoacetyltriglycine (MAG3) scan was performed, and regions of interest were drawn on the kidneys, and perirenal and lateral backgrounds. Differential renal function was calculated with and without background subtraction at 30-second intervals from 0.5 to 3 minutes after injection of 99mTc-MAG3. The effects of age, sex, obstruction, site and size of the hydronephrotic kidney were analyzed using the generalized estimating equations method.

RESULTS

There were 11 right and 33 left hydronephrotic kidneys. An obstructive renographic pattern was present in 33 cases. The trends of differential renal function according to intervals were different between kidneys with and without background subtraction, and differential renal function increased significantly as size increased (p <0.05). Differential renal function of the hydronephrotic kidney with an obstructive renographic pattern increased with time when perirenal or no background subtraction was applied (p <0.05). The effects of age, sex or laterality on differential renal function were not significant. Supranormal function (differential renal function 55% or greater) was present regardless of background subtraction methods and measurement time.

CONCLUSIONS

Differential renal function is higher in larger hydronephrotic kidney but function of the kidney with an obstructive pattern is overestimated on later phases of 99mTc-MAG3 renal scan. Supranormal differential renal function is real and may be pathologic since it is prone to occur in larger obstructive hydronephrotic kidneys.

Chaoslike behavior in nonchaotic systems at finite computation precision

The dynamical behavior of a two-dimensional map is investigated numerically. A chaoslike behavior, i.e., a nonsmooth distribution of the attractor and seemly sensitive dependence of the motion on initial condition is found as the system state is nonchaotic (both Lyapunov exponents are nonpositive). The key point for this strange behavior is that the mode corresponding to the second negative Lyapunov exponent contains positive local Lyapunov exponent segments. It is argued that this kind of behavior may be typical and easily observed in practical numerical computations and experiments where small noise is inevitable.

Line emission in single-bubble sonoluminescence

We report that single-bubble sonoluminescence (SBSL) at low light intensities produces emission bands similar to multibubble sonoluminescence (MBSL) for pure noble gas bubbles. A smooth crossover between SBSL and MBSL behavior can be induced by varying the acoustic pressure amplitude and thereby the intensity of the light emitted. The relative intensity of the band emission depends both on the molecular weight of the noble gas and the water temperature. Our results provide a connection between the mechanisms SBSL and MBSL and show that molecular emission plays a role in SBSL.

Reproducibility of scanning laser polarimetry (GDx) of peripapillary retinal nerve fiber layer thickness in normal subjects

PURPOSE

To assess the reproducibility of measurement of retinal nerve fiber layer (RNFL) thickness among subjects using the GDx Nerve Fiber Analyzer (NFA).

METHODS

One eye of each of five young and healthy volunteers was imaged by three newly trained technicians (R.-H.P, K.-R.K., and S.-T.K.). Each volunteer was scanned six consecutive times for five independent times within a 1-month period. One composite image was selected out of three best images per session. Intra- and interoperator reproducibilities were calculated and the influence of placement of measurement ellipse by a single operator on interobserver reproducibility was also investigated.

RESULTS

Mean coefficients of variation for total integral value of RNFL were 3.67 +/- 1.47%, 3.86 +/- 2.13%, and 4.16 +/- 1.97%, respectively for the three technicians. Interoperator variability was not statistically significant (P = 0.075), and the difference was even less if a single ellipse drawn by one operator was used in all measurements (P = 0.1528) by repeated-measures analysis of variance (ANOVA).

CONCLUSIONS

The results suggest that GDx NFA may provide acceptable intraoperator as well as interoperator reproducibility among Asian eyes.

Ethnic differences in the age-related distribution of serum prostate-specific antigen values: a study in a healthy Korean male population

OBJECTIVES

To further improve the use of prostate-specific antigen (PSA) as a screening test for prostate cancer in Asian countries, we sought to establish the normal distribution of serum PSA values in Korean men, because, until recently, studies conducted to establish normal serum PSA values have involved few Asian populations.

METHODS

Between May 1995 and June 1997, 5805 healthy Korean men 30 to 79 years old who visited our hospital for a routine health checkup were entered into a prospective study of early screening for prostate cancer. All men underwent detailed clinical examinations, including a digital rectal examination and serum PSA determination. All men who were more than 50 years old with abnormal digital rectal examination findings and/or an elevated serum PSA level (greater than 4.0 ng/mL) also underwent transrectal ultrasound-guided sextant biopsy. Four were found to have cancer and were excluded from the analysis.

RESULTS

The median serum PSA concentration (5th to 95th percentile range) was 0.8 ng/mL (0.2 to 1.8) for patients 30 to 39 years old (n = 1382); 0.8 ng/mL (0.2 to 2.0) for patients 40 to 49 years old (n = 1776); 0.9 ng/mL (0.2 to 2.4) for those 50 to 59 years old (n = 1775); 1.0 ng/mL (0.2 to 3.9) for men 60 to 69 years old (n = 746); and 1.3 ng/mL (0.5 to 6.3) for patients 70 to 79 years old (n = 122). The serum PSA concentration correlated with age (P <0.001), with an increase by approximately 1.2% annually, although the statistical correlation was weak (r = 0.16). Almost no change occurred in the median serum PSA value in patients 50 years old or younger; a gradual increase was observed in patients older than 50. In those 50 years old or older, the median and 95th percentile serum PSA values for Korean men were lower than those for white men.

CONCLUSIONS

Contrary to earlier observations that the serum PSA level strongly correlates with age, the influence of age on serum PSA was found to be weaker in this study. Moreover, the results also demonstrated that the distribution of the serum PSA level differs along ethnic lines. The cutoff value for serum PSA in mass screening for prostate cancer should be adjusted in nonwhite races.

[Change of 5-fluorouracil penetration in blood-pancreatic barrier of rats after high-dose radiotherapy]

OBJECTIVE

The high-dose intraoperative radiotherapy has become an important therapy to control local recur of pancreatic carcinoma. But the relevant effect of high-dose radiotherapy on chemotherapy is not clear now.

METHODS

We studied the effect of high-dose radiotherapy to the penetration of 5-FU (5-Fluorouracil) in blood-pancreatic barrier of rats after the pancreatic region of the rats had treated with 10(Gy) external beam radiotherapy, the penetration ratio (PR) of 5-FU in the pancreatic tissue was investigated with HPLC assay.

RESULTS

We found the PR increased with the time processing. And reached the peak on the 6th day, (PR = 0.8300 +/- 0.1662, P < 0.05). Then, the PR began to descend and was 0.7028 on the 10th day. But it was still significantly higher than control group (P < 0.05).

CONCLUSION

After the treatment of high-dose radiotherapy, in addition to chemotherapy on the 4th day, and finished the course on the 10th day, the effect of radiotherapy may improve chemotherapy significantly.

Quantum hall ferromagnetism in a two-dimensional electron system

Experiments on a nearly spin degenerate two-dimensional electron system reveals unusual hysteretic and relaxational transport in the fractional quantum Hall effect regime. The transition between the spin-polarized (with fill fraction nu = 1/3) and spin-unpolarized (nu = 2/5) states is accompanied by a complicated series of hysteresis loops reminiscent of a classical ferromagnet. In correlation with the hysteresis, magnetoresistance can either grow or decay logarithmically in time with remarkable persistence and does not saturate. In contrast to the established models of relaxation, the relaxation rate exhibits an anomalous divergence as temperature is reduced. These results indicate the presence of novel two-dimensional ferromagnetism with a complicated magnetic domain dynamic.

Evidence for nucleic acid binding ability and nucleosome association of Bombyx mori nucleopolyhedrovirus BRO proteins

The Bombyx mori nucleopolyhedrovirus (BmNPV) genome contains five related members of the bro gene family, all of which are actively expressed in infected BmN cells. Although their functions are unknown, their amino acid sequences contain a motif found in all known viral and prokaryotic single-stranded DNA binding proteins. To determine if they bind to nucleic acids, we fractionated the nuclei of BmNPV-infected BmN cells using a histone extraction protocol. We detected BRO-A, BRO-C, and BRO-D in the histone H1 fraction using anti-BRO antibodies. Micrococcal nuclease treatment released these BRO proteins from the chromatin fraction, suggesting their involvement in nucleosome structures. Chromatographic fractionation showed that BRO-A and/or BRO-C interacted with core histones. Expression of partial sequences of BRO-A proved that the N-terminal 80 amino acid residues were required for DNA binding activity. We also demonstrated that BmNPV BRO proteins underwent phosphorylation and ubiquitination followed by proteasome degradation, which may explain their distribution in the cytoplasm as well as the nucleus. We propose that BRO-A and BRO-C may function as DNA binding proteins that influence host DNA replication and/or transcription.