Mistic-fused expression of algal rhodopsins in Escherichia coli and its photochemical properties

BACKGROUND

Since algal rhodopsins, the eukaryotic seven-transmembrane proteins, are generally difficult to express in Escherichia coli, eukaryotic cells have been used for heterologous expression. Mistic, a membrane-associated protein that was originally discovered in Bacillus subtilis, has been shown to improve the expression levels of many foreign integral membrane proteins in E. coli when used as a fusion partner linked to the N-terminus of cargo proteins.

METHODS

Here, we expressed two algal rhodopsins with N- and C-terminal Mistic domains in E. coli-Acetabularia rhodopsin I (ARI) and Chlamydomonas sensory rhodopsin B (CSRB, channel rhodopsin 2). UV/VIS spectroscopy, pH titration of proton acceptor residue, laser-induced photolysis and electrophysiological measurement were used for investigating important residues in proton transport and spectroscopic characters of the proteins.

RESULTS

Protein yield of two algal rhodopsins was enhanced, obtaining 0.12mg of Mistic-ARI and 0.04mg of Mistic-CSRB per liter of culture. Spheroplast expression Mistic-ARI had outward proton-pumping activity, indicating protein functionality. Asp89 of ARI changed its protonation state by light absorption, and Asp100 was important for O(600) formation. Electrophysiology revealed that both residues took part in proton transport. The spectroscopic analyses of Mistic-CSRB revealed its characteristics.

CONCLUSIONS

Fusion to the membrane-integrating protein Mistic can enhance overexpression of eukaryotic type I rhodopsins in E. coli.

GENERAL SIGNIFICANCE

These findings indicate that Mistic fusion and E. coli expression method could be an effective, low cost technique for studying eukaryotic membrane proteins. This may have useful implications, for example, in studying structural characteristics and optogenetics for rhodopsins.

DNA binding activity of Anabaena sensory rhodopsin transducer probed by fluorescence correlation spectroscopy

Anabaena sensory rhodopsin transducer (ASRT) is believed to be a major player in the photo-signal transduction cascade, which is triggered by Anabaena sensory rhodopsin. Here, we characterized DNA binding activity of ASRT probed by using fluorescence correlation spectroscopy. We observed clear decrease of diffusion coefficient of DNA upon binding of ASRT. The dissociation constant, K(D), of ASRT to 20 bp-long DNA fragments lied in micro-molar range and varied moderately with DNA sequence. Our results suggest that ASRT may interact with several different regions of DNA with different binding affinity for global regulation of several genes that need to be activated depending on the light illumination.

PCDHB14- and GABRB1-like nervous system developmental genes are altered during early neuronal differentiation of NCCIT cells treated with ethanol

Ethanol (EtOH) exposure during embryonic development causes dysfunction of the central nervous system (CNS). Here, we examined the effects of chronic EtOH on gene expression during early stages of neuronal differentiation. Human embryonic carcinoma (NCCIT) cells were differentiated into neuronal precursors/lineages in the presence or absence of EtOH and folic acid. Gene expression profiling and pathway analysis demonstrated that EtOH deregulates many genes and pathways that are involved in early brain development. EtOH exposure downregulated several important genes, such as PCDHB14, GABRB1, CTNND2, NAV3, RALDH1, and OPN5, which are involved in CNS development, synapse assembly, synaptic transmission, and neurotransmitter receptor activity. GeneGo pathway analysis revealed that the deregulated genes mapped to disease pathways that were relevant to fetal alcohol spectrum disorders (FASD, such as neurotic disorders, epilepsy, and alcohol-related disorders). In conclusion, these findings suggest that the impairment of the neurological system or suboptimal synapse formation resulting from EtOH exposure could underlie the neurodevelopmental disorders in individuals with FASD.

100 fs photo-isomerization with vibrational coherences but low quantum yield in Anabaena Sensory Rhodopsin

Counter-intuitive photochemistry: in Anabaena Sensory Rhodopsin, the retinal 13-cis isomer isomerizes much faster than all-trans ASR, but with a 3-times lower quantum yield.

Charge-selective membrane protein patterning with proteoliposomes

A novel method to fabricate transmembrane protein (TP) embedded lipid bilayers has been developed, resulting in an immobilized, but biologically functioning TP embedded lipid layer precisely in the targeted patterns.

Light-driven Na(+) pump from Gillisia limnaea: a high-affinity Na(+) binding site is formed transiently in the photocycle

A group of microbial retinal proteins most closely related to the proton pump xanthorhodopsin has a novel sequence motif and a novel function. Instead of, or in addition to, proton transport, they perform light-driven sodium ion transport, as reported for one representative of this group (KR2) from Krokinobacter. In this paper, we examine a similar protein, GLR from Gillisia limnaea, expressed in Escherichia coli, which shares some properties with KR2 but transports only Na(+). The absorption spectrum of GLR is insensitive to Na(+) at concentrations of ≤3 M. However, very low concentrations of Na(+) cause profound differences in the decay and rise time of photocycle intermediates, consistent with a switch from a "Na(+)-independent" to a "Na(+)-dependent" photocycle (or photocycle branch) at ∼60 μM Na(+). The rates of photocycle steps in the latter, but not the former, are linearly dependent on Na(+) concentration. This suggests that a high-affinity Na(+) binding site is created transiently after photoexcitation, and entry of Na(+) from the bulk to this site redirects the course of events in the remainder of the cycle. A greater concentration of Na(+) is needed for switching the reaction path at lower pH. The data suggest therefore competition between H(+) and Na(+) to determine the two alternative pathways. The idea that a Na(+) binding site can be created at the Schiff base counterion is supported by the finding that upon perturbation of this region in the D251E mutant, Na(+) binds without photoexcitation. Binding of Na(+) to the mutant shifts the chromophore maximum to the red like that of H(+), which occurs in the photocycle of the wild type.

Photosynthetic biomineralization of radioactive Sr via microalgal CO2 absorption

Water-soluble radiostrontium ((90)Sr) was efficiently removed as a carbonate form through microalgal photosynthetic process. The immobilization of soluble (90)Sr radionuclide and production of highly-precipitable radio-strontianite ((90)SrCO3) biomineral are achieved by using Chlorella vulgaris, and the biologically induced mineralization drastically decreased the (90)Sr radioactivity in water to make the highest (90)Sr removal ever reported. The high-resolution microscopy revealed that the short-term removal of soluble (90)Sr by C. vulgaris was attributable to the rapid and selective carbonation of (90)Sr together with the consumption of dissolved CO2 during photosynthesis. A small amount of carbonate in water could act as Sr(2+) sinks through the particular ability of the microalga to make the carbonate mineral of Sr stabilized firmly at the surface site.

Prognostic and predictive values of EGFR overexpression and EGFR copy number alteration in HER2-positive breast cancer

Background:

Epidermal growth factor receptor (EGFR) is overexpressed in a subset of human epidermal growth factor receptor 2 (HER2)-positive breast cancers, and coexpression of HER2 and EGFR has been reported to be associated with poor clinical outcome. Moreover, interaction between HER2 and EGFR has been suggested to be a possible basis for trastuzumab resistance.

Methods:

We analysed the clinical significance of EGFR overexpression and EGFR gene copy number alterations in 242 HER2-positive primary breast cancers. In addition, we examined the correlations between EGFR overexpression, trastuzumab response and clinical outcome in 447 primary, and 112 metastatic HER2-positive breast cancer patients treated by trastuzumab.

Results:

Of the 242 primary cases, the level of EGFR overexpression was 2+ in 12.7% and 3+ in 11.8%. High EGFR gene copy number was detected in 10.3%. Epidermal growth factor receptor overexpression was associated with hormone receptor negativity and high Ki-67 proliferation index. In survival analyses, EGFR overexpression, but not high EGFR copy number, was associated with poor disease-free survival in all patients, and in the subgroup not receiving adjuvant trastuzumab. In 447 HER2-positive primary breast cancer patients treated with adjuvant trastuzumab, EGFR overexpression was also an independent poor prognostic factor. However, EGFR overexpression was not associated with trastuzumab response, progression-free survival or overall survival in the metastatic setting.

Conclusions:

Epidermal growth factor receptor overexpression, but not high EGFR copy number, is a poor prognostic factor in HER2-positive primary breast cancer. Epidermal growth factor receptor overexpression is a predictive factor for trastuzumab response in HER2-positive primary breast cancer, but not in metastatic breast cancer.

Cyanobacterial light-driven proton pump, gloeobacter rhodopsin: complementarity between rhodopsin-based energy production and photosynthesis

A homologue of type I rhodopsin was found in the unicellular Gloeobacter violaceus PCC7421, which is believed to be primitive because of the lack of thylakoids and peculiar morphology of phycobilisomes. The Gloeobacter rhodopsin (GR) gene encodes a polypeptide of 298 amino acids. This gene is localized alone in the genome unlike cyanobacterium Anabaena opsin, which is clustered together with 14 kDa transducer gene. Amino acid sequence comparison of GR with other type I rhodopsin shows several conserved residues important for retinal binding and H⁺ pumping. In this study, the gene was expressed in Escherichia coli and bound all-trans retinal to form a pigment (λmax  = 544 nm at pH 7). The pK_a of proton acceptor (Asp121) for the Schiff base, is approximately 5.9, so GR can translocate H⁺ under physiological conditions (pH 7.4). In order to prove the functional activity in the cell, pumping activity was measured in the sphaeroplast membranes of E. coli and one of Gloeobacter whole cell. The efficient proton pumping and rapid photocycle of GR strongly suggests that Gloeobacter rhodopsin functions as a proton pumping in its natural environment, probably compensating the shortage of energy generated by chlorophyll-based photosynthesis without thylakoids.

A role of Anabaena sensory rhodopsin transducer (ASRT) in photosensory transduction

In 2003, Anabaena sensory rhodopsin (ASR), a membrane-bound light sensor protein, was discovered in cyanobacteria. Since then, a large number of functions have been described for ASR, based on protein biochemical and biophysical studies. However, no study has determined the in vivo mechanism of photosensory transduction for ASR and its transducer protein (ASRT). Here, we aimed to determine the role of ASRT in physiological photo-regulation. ASRT is known to be related to photochromism, because it regulates the expression of phycocyanin (cpc-gene) and phycoerythrocyanin (pec gene), two major proteins of the phycobilisome in cyanobacteria. By examining wild type and knockout mutant Anabaena cells, we showed that ASRT repressed the expression of these two genes. We also demonstrated physical interactions between ASRT, ASR, and the promoter regions of cpc, pec, kaiABC (circadian clock gene) and the asr operon, both in vitro and in vivo. Binding assays indicated that ASRT had different sites of interaction for binding to ASR and DNA promoter regions. ASRT also influenced the retinal re-isomerization rate in dark through a physical interaction with ASR, and it regulated reporter gene expression in vivo. These results suggested that ASRT relayed the photosignal from ASR and directly regulated gene expression.

Abstract OT3-1-08: The PROCEED trial KCSG BR11-01: Phase III multicenter randomized open label study of irinotecan plus capecitabine versus capecitabine in patients previously treated with anthracycline and taxane for HER2 negative metastatic breast cancer

Background: Most patients with metastatic breast cancer (MBC) experience disease progression after being treated with an anthracycline or taxane. Irinotecan, a semisynthetic agent derived from the natural alkaloid camptothecin is metabolized to the active metabolite SN-38 which targets topoisomerase I leading to single and double strand DNA breaks. Irinotecan as a single agent demonstrated tumor activity with an objective response rate ranging from 5 to 23% in patients with MBC refractory to taxane and anthracycline. Irinotecan increased the activity of 5-FU, the active metabolite of capecitabine, and overcomes the negative effect of thymidylate synthase overexpression, which is the main target of an active metabolite of 5-FU. A phase II study that evaluated the efficacy and safety of irinotecan and capecitabin combination (IX) showed that the median progression free survival (PFS) was 7.6 months (95% CI, 5.0-10.2months), and the median OS was 22.6 months (95% CI, 15.4 – 29.8 months) with good tolerability in anthracycline and taxane pretreated MBC patients. Based on these results, we planned to conduct a multicenter, randomized phase III study which assesses the efficacy of irinotecan and capecitabine combination therapy compared with capecitabine alone in patients with anthracycline and taxane resistant MBC.

Methods: In this trial, patients with HER2 normal tumor who previously received anthracycline and taxane based chemotherapies are enrolled. Eligible patients are randomly assigned in a 1:1 ratio to receive irinotecan plus capecitabine or capecitabine alone. The primary end point of this trial is PFS and a total number of accrual patients will be 222. Randomization is done using a random block size permutation method and stratified by hormone receptor status (negative vs. positive), first line vs. ≥second lines, visceral metastasis (negative vs. positive). Patients receive irinotecan at 80 mg/m2 on day 1 and 8 every 3 weeks and capecitabine 1000mg/m2 bid from day 1 to day 14 every 3 weeks. In control arm, patients receive capecitabine 1250mg/m2 bid from day 1 to day 14 every 3 weeks. Response will be assessed using RECIST1.1 criteria and toxicity will be graded according to NCI-CTCAE 4.0 criteria. Study Status: A total of 107 patients consented for the study since June 2011, and accrual is ongoing. Clinical trial information: NCT01501669.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT3-1-08.

Abstract P6-05-17: A study of investigating biologic markers of anti-tumor effects of zoledronic acid and taxane-based chemotherapy for metastatic breast cancer in bone: A prospective, multi-center, non-randomized study (BEAT-ZO) (KCSG BR10-13)

Introduction

Currently the predictive factors for taxane(T)-zoledronic acid(ZA) combination therapy in breast cancer patient with bone metastasis have not been established except tumor biology. The aim of this study is to investigate potential biologic markers of anti-tumor effects of and T-ZA for metastatic breast cancer(MBC) in bone.

Methods

Patients(pts) with MBC in bone being treated with docetaxel or paclitaxel based chemotherapy and ZA for the first time in metastatic setting were enrolled. Blood samples were collected serially at baseline, after 2 cycles to examine markers for angiogenesis(VEGF, VEGFR2, FGF-2, PDGF-AA), immune modulation (IL-2, IFN-γ, MCP-2, IL-10, TGF-β, IL-12, TNF-α, IL-17, IL-6) and apoptosis (TRAIL).

Results

Of enrolled total 58 pts, 31 pts (median age 49; ECOG 0-1 96.8%; menopause 58.1%; invasive ductal carcinoma 92.9%; ER-(+) 77.4%; HER2-(+) 35.5%; visceral metastasis 35.5%) were included in this preliminary analysis.

Fifteen pts received docetaxel-based chemotherapy and the remainder were treated with paclitaxel-based chemotherapy. Median 6 (range: 1 – 23) cycles per pt were administered. In per-protocol analysis, overall RR was 55.6% [95% CI: 37.3 – 72.4]. After the median follow-up of 13.67 months(mo.), median PFS was 9.13 mths [95% CI: 3.25 – 15.02]. Osteonecrosis of the jaw was reported in only one patient (3.2%).

In the baseline biomarker analysis, the pts with triple-negative breast cancer (TNBC) showed significantly higher VEGF level than hormone (+) or HER-2 (+) pts (518.7 vs 151.6 and 179.2 pg/ml, p = 0.041). Median baseline TRAIL was significantly higher in the postmenopausal women than the premenopausal women (52.0 vs 32.0 pg/ml, p = 0.038).

For the group as a whole, there was a borderline significant reduction in median serum MCP-2 level (41.4 to 34.1 pg/ml, p = 0.066) and an increasing tendency in median serum TRAIL level (44.7 to 54.5 pg/ml, p = 0.080) after 2 cycles of treatment. Median percentage reduction in serum VEGF in the TNBC group was -50.0% compared with +37.7% in others (p = 0.099). Median changes in MCP-2 was -36.4% in hormone (+) group compared with +7.6% in others (p = 0.008).

The pts who were progression free at 6 mths showed significant increase in median TNF-α after 2cycles of treatment, while the pts who experienced disease progression within 6 mths showed significant decrease in TNF-α level (p = 0.028) and there was a similar tendency in TRAIL level (p = 0.157).

The pts with increase of serum TNF-α or TRAIL levels from baseline showed significant improvement of PFS comparing the pts with no change or decrease of TNF-α and TRAIL levels (13.3 vs 5.93 mths, p = 0.012).

We are planning to perform additional analysis. The significance of serum TGF-β level on prognosis and the data of the remainder will be presented on the poster.

Conclusion

In this study, baseline levels and changes of biomarkers suggest potentially relevant interactions between menopausal status, tumor biology and treatment. Especially, TNF-α and TRAIL may be potential early marker for zoledronic acid and taxane-based chemotherapy for MBC in bone. Larger studies are needed to validate these complex interactions.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-05-17.

Abstract P1-08-38: HER2 heterogeneity affects trastuzumab responses and survival in patients with HER2-postive metastatic breast cancer

Purpose: Heterogeneity of HER2 gene amplification is found in a subset of breast cancers. However, it is not known whether breast cancers with heterogeneous HER2 amplification respond differently to HER2-targeted therapy than those with homogeneous amplification. In this study, we investigated the relationship between HER2 heterogeneity and trastuzumab resistance and clinical outcomes in patients with HER2-positive metastatic breast cancer.

Patients and methods: We studied tumor tissues from 127 patients with HER2-positive metastatic breast cancers who had received trastuzumab-based chemotherapy. Regional and genetic heterogeneity of HER2 amplification was determined in three different areas of each tumor by immunohistochemistry (IHC) and silver in situ hybridization. We also assessed the overall levels of HER2 amplification, and the proportion of tumor cells with a HER2/CEP17 ratio >2.2 or HER2 overexpression (IHC score of 3+). HER2status including HER2 heterogeneity was correlated with trastuzumab responses and survival of the patients.

Results: HER2regional and genetic heterogeneity was confirmed in 7.8% and 3.6% of cases, respectively. Poor response to trastuzumab was associated with overall low-level amplification, HER2regional heterogeneity, HER2/CEP17 ratio >2.2 in <80% of tumor cells, and HER2 IHC score of 3+ in <75% of tumor cells. In survival analyses, low-level HER2 amplification, HER2regional heterogeneity, and HER2/CEP17 ratio >2.2 in <80% of tumor cells were associated with shorter time to progression and lower overall survival in univariate and multivariate analyses.

Conclusion: Accurate assessment of HER2 status including HER2 heterogeneity is important in predicting trastuzumab responses and outcomes in patients with HER2-positive metastatic breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-08-38.

S-1 plus irinotecan and oxaliplatin for the first-line treatment of patients with metastatic colorectal cancer: a prospective phase II study and pharmacogenetic analysis

BACKGROUND

S-1 is an oral fluoropyrimidine that mimics infusional 5-fluorouracil. The aim of this phase II trial was to explore the clinical efficacy of the triplet regimen TIROX, which consists of S-1, irinotecan and oxaliplatin.

METHODS

Forty-two chemo-naive patients with metastatic colorectal cancer (mCRC) were planned to be enrolled and be treated with irinotecan 150 mg m(-2) followed by oxaliplatin 85 mg m(-2) on day 1 and S-1 80 mg m(-2) per day from day 1 to 14 every 3 weeks. Polymorphisms in the UGT1A1, UGT1A6, UGT1A7 and CYP2A6 genes were analysed.

RESULTS

Between July 2007 and February 2008, 43 patients were enrolled. An objective response was noted in 29 patients (67.4%, 95% confidence interval: 53.4-81.4), of which 2 achieved durable complete responses. The median progression-free survival was 10.0 months and the median overall survival was 19.2 months. Significant grade 3 or 4 adverse events were neutropenia (45.2%), febrile neutropenia (9.5%), diarrhoea (7.1%) and vomiting (9.5%). Increased gastrointestinal toxicities were associated with the presence of UGT1A6*2 or UGT1A7*3 and an improved tumour response was noted in those without variant alleles of CYP2A6 or UGT1A1*60.

CONCLUSION

The combination of S-1, irinotecan and oxaliplatin showed favourable efficacy and tolerability in untreated patients with mCRC.

Symptomatic mucoid degeneration of the anterior cruciate ligament

PURPOSE

Mucoid degeneration of the anterior cruciate ligament (ACL) is a little-known entity. The aim of this study was to detail the clinical, radiological, arthroscopic and pathological findings of this condition and to report clinical outcomes following arthroscopic partial excision of the ACL.

METHODS

Between 1999 and 2009, 80 knees in 78 patients were diagnosed as having mucoid degeneration of the ACL based on MRI and clinical findings, and subsequently underwent arthroscopic treatment. Of these, 68 knees in 66 patients, with a median age of 51 years (range, 35-75 years), were followed-up for at least one year.

RESULTS

All patients had insidious onset of knee pain, while 56 knees (82 %) had associated extension deficits and 36 knees (53 %) had restricted flexion. MRI findings typically showed diffuse thickening and increased signal intensity of the ACL. Arthroscopic examination revealed notch impingement and bulging of hypertrophied ACL into lateral compartments. Associated lesions included meniscal tears in 33 knees and chondral lesions of at least Outerbridge grade 2 in 56 knees. All knees underwent arthroscopic partial excision of the hypertrophied ACL, with three undergoing preoperative and 30 undergoing concomitant meniscectomies. Pain relief was achieved in 58 of 62 knees (94 %) following partial excision of the ACL. Extension deficits were normalized in 49 of 56 knees (88 %), and restricted flexion was normalized in 33 of 36 affected knees (92 %). Four knees of four patients had postoperative symptoms of anterior instability.

CONCLUSIONS

Pain and limitation of motion due to mucoid degeneration of the ACL can be improved by arthroscopic partial excision of the ACL with or without notchplasty. However, one potential complication is the development of postoperative symptoms of anterior instability.

LEVEL OF EVIDENCE

Retrospective study, Level IV.

Percolated pore networks of oxygen plasma-activated multi-walled carbon nanotubes for fast response, high sensitivity capacitive humidity sensors

We report on the preparation of capacitive-type relative humidity sensors incorporating plasma-activated multi-wall carbon nanotube (p-MWCNT) electrodes and on their performance compared with existing commercial technology. Highly open porous conductive electrodes, which are almost impossible to obtain with conventional metal electrodes, are fabricated by spray-depositing MWCNT networks on a polyimide layer. Oxygen plasma activation of the MWCNTs is also explored to improve the water adsorption of the MWCNT films, by introducing oxygen-containing functional groups on the CNT surface. Polyimide humidity sensors with optimized p-MWCNT network electrodes exhibit exceptionally fast response times (1.5 for adsorption and 2 s for desorption) and high sensitivity (0.75 pF/% RH). These results may be partially due to their percolated pore structure being more accessible for water molecules, expending the diffusion of moisture to the polyimide sensing film, and partially due to the oxygenated surface of p-MWCNT films, allocating more locations for adsorption or attraction of water molecules to contribute to the sensitivity.

Effect of complementary and alternative medicine on the survival and health-related quality of life among terminally ill cancer patients: a prospective cohort study

BACKGROUND

We evaluated whether complementary and alternative medicine (CAM) use influenced outcomes [survival and health-related quality of life (HRQOL)] of cancer patients whose condition had just been judged terminal.

PATIENTS AND METHODS

From July 2005 to October 2006, we conducted a prospective cohort study of 481 terminally ill cancer patients at 11 university hospitals and the National Cancer Center in Korea. We assessed how the use of CAM affected HRQOL and survival.

RESULTS

In a follow-up of 481 patients and 163.8 person-years, we identified 466 deceased cases. On multivariate analyses, CAM users did not have better survival compared with nonusers [adjusted hazard ratio (aHR), 0.91; 95% confidence interval (CI) 0.74-1.10]. Among mind-body interventions, prayer showed significantly worse survival (aHR, 1.56; 95% CI, 1.00-2.43). Clinically, CAM users reported significantly worse cognitive functioning (-11.6 versus -1.3; P < 0.05) and fatigue (9.9 versus -1.0; P < 0.05) than nonusers. Compared with nonusers in subgroup analysis, users of alternative medical treatments, prayer, vitamin supplements, mushrooms, or rice and cereal reported clinically significant worse changes in some HRQOL subscales.

CONCLUSION

While CAM did not provide any definite survival benefit, CAM users reported clinically significant worse HRQOLs.

Application of a sensitive near-field microwave microprobe to the nondestructive characterization of microbial rhodopsin

We study the opto-electrical properties of Natronomonas pharaonis sensory rhodopsin II (NpSRII) by using a near-field microwave microprobe (NFMM) under external light illumination. To investigate the possibility of application of NFMM to biological macromolecules, we used time dependent properties of NPSRII before/after light activation which has three distinct states - ground-state, M-state, and O-state. The diagnostic ability of NFMM is demonstrated by measuring the microwave reflection coefficient (S(11)) spectrum of NpSRII under steady-state illumination in the wavelength range of 350-650 nm. Moreover, we present microwave reflection coefficient S(11) spectra in the same wavelength range for two fast-photocycling rhodopsins: green light-absorbing proteorhodopsin (GPR) and Gloeobacter rhodopsin (GR). In addition the frequency sweep shift can be detected completely even for tiny amounts of sample (∼10(-3) OD of rhodopsin). Based on these results NFMM shows both very high sensitivity for detecting conformational changes and produces a good time-resolved spectrum.

Abstract P3-12-05: Clinical features and outcomes of leptomeningeal metastasis in patients with breast cancer: a single center experience

Background: Leptomeningeal metastasis (LM) is one of the major problems in managing metastatic breast cancer because of LM typically carries a devastating prognosis and often represents a terminal event. We analyzed the clinical features and outcomes of LM in patients with breast cancer.

Methods: We retrospectively reviewed the medical records of patients who were diagnosed with LM from breast cancer between 2002 and 2012 at Asan Medical Center.

Results: Of the 95 LM patients by cytologically proven (n = 81) or radiologically diagnosed (n = 14), 57 (60%) had an ECOG performance status (PS) ≥ 3, and the median age was 47 years (range, 26–72 years). The patients were diagnosed with LM after a median of 10.3 months (95% CI, 5.5–15.0 months) from the time of diagnosis of metastatic breast cancer. LM was present in 2 patients at the time of initial diagnosis. Twenty-three patients (24.2%) had isolated CNS metastasis, and 6 (6.3%) had only LM without any detectable metastasis sites. At the time of diagnosis of LM, 46 patients (48.4%) presented with coincidental failure of systemic disease control. Seventy-eight patients (82.1%) underwent intrathecal chemotherapy (methotrexate; n=78, thiotepa; n=11), resulting in one-third of cytologic negative conversion (n = 26), and 41 (43.2%) received systemic chemotherapy. The overall median survival time was 3.3 months (95% CI, 2.5–4.2 months) and 7.8% of the patients survived for more than 1 year. Overall survival tended to be better in patients who achieved cytologic negative conversion to intrathecal chemotherapy than those did not (median 4.5 months versus 3.2 months, P = 0.241). Overall survival was not different according to subtypes; hormone receptor (+), HER2 (+), and triple negative (median 3.6 months, 3.3 months, and 3.2 months, P = 0.937). Multivariate analysis demonstrated that ECOG PS ≥ 3 (HR = 2.09, 95% CI 1.21–3.58, P = 0.007), coincidental failure of systemic disease control at LM (HR = 3.01, 95% CI 1.76–5.15, P &lt; 0.001), and systemic chemotherapy after LM (HR = 0.40, 95% CI 0.24–0.68, P = 0.001) were independent factors associated with survival.

Conclusions: The prognosis for patients with LM from breast cancer was still poor. Systemic chemotherapy in addition to intrathecal chemotherapy might confer a survival benefit, even after the detection of LM.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-12-05.

Characterization of the chimeric seven-transmembrane protein containing conserved region of helix C-F of microbial rhodopsin from Ganges River

Proteorhodopsin (PR) is a light-driven proton pump that has been found in a variety of marine bacteria. Recently, many PR-like genes were found in non-marine environments. The goal of this study is to explore the function of rhodopsins that exist only as partial proteo-opsin genes using chimeras with marine green PR (GPR). We isolated nine partial genes of PR homologues using polymerase chain reaction (PCR) and chose three homologues of GPR from the surface of the Ganges River, which has earned them the name "CFR, Chimeric Freshwater Rhodopsin." In order to characterize the proteins, we constructed the cassette based on GPR sequence without helices C to F and inserted the isolated conserved partial sequences. When expressed in E. coli, we could observe light-driven proton pumping activity similar to proteorhodopsin, however, photocycle kinetics of CFRs are much slower than proteorhodopsin. Half-time decay of O intermediates of CFRs ranged between 143 and 333 ms at pH 10; their absorption maxima were between 515 and 522 nm at pH 7. We can guess that the function of native rhodopsin, a retinal protein of fresh water bacteria, may be a light-driven proton transport based on the results from chimeric freshwater rhodopsins. This approach will enable many labs that keep reporting partial PCR-based opsin sequences to finally characterize their proteins.

Relation between mucoid degeneration of the anterior cruciate ligament and posterior tibial slope

PURPOSE

The purpose was to analyze the association between posterior tibial slope (PTS) and mucoid degeneration of the anterior cruciate ligament (ACL).

METHODS

From October 1999 to May 2010, 84 arthroscopies were performed in 82 patients (18 men and 64 women) with mucoid degeneration of the ACL. The mean patient age was 53 years (range, 25 to 75 years). In addition to this patient group (group I), the study included a control group without mucoid degeneration of the ACL that was randomly matched for age, sex, body mass index, left or right side, and associated lesions (group II). For each group, the diagnosis was made by use of magnetic resonance imaging and arthroscopy, and a plain lateral radiograph was used to measure the PTS.

RESULTS

The mean PTS was 13.5° ± 2.6° (range, 8.2° to 19.5°) in group I and 9.4° ± 2.5° (range, 4.8° to 15.5°) in group II. The mean PTS in group I was significantly greater than that in group II (P < .001). For group I, the mean PTS of the involved knee was significantly greater than that of the uninvolved contralateral knee (P = .044). There were no differences according to age, sex, left or right side, body weight, and body mass index (P > .05).

CONCLUSIONS

Mucoid degeneration of the ACL was found to be associated with an increased PTS. The patients with mucoid degeneration of the ACL had a greater mean PTS than matched control patients (13.5° v. 9.4°, P < .001).

LEVEL OF EVIDENCE

Level III, diagnostic study of nonconsecutive patients without consistently applied gold standard.