Development and validation of transferable amide I vibrational frequency maps for peptides

Infrared (IR) spectroscopy of the amide I band has been widely utilized for the analysis of peptides and proteins. Theoretical modeling of IR spectra of proteins requires an accurate and efficient description of the amide I frequencies. In this paper, amide I frequency maps for protein backbone and side chain groups are developed from experimental spectra and vibrational lifetimes of N-methylacetamide and acetamide in different solvents. The frequency maps, along with established nearest-neighbor frequency shift and coupling schemes, are then applied to a variety of peptides in aqueous solution and reproduce experimental spectra well. The frequency maps are designed to be transferable to different environments; therefore, they can be used for heterogeneous systems, such as membrane proteins.

Robust estimation for ordinary differential equation models

Applied scientists often like to use ordinary differential equations (ODEs) to model complex dynamic processes that arise in biology, engineering, medicine, and many other areas. It is interesting but challenging to estimate ODE parameters from noisy data, especially when the data have some outliers. We propose a robust method to address this problem. The dynamic process is represented with a nonparametric function, which is a linear combination of basis functions. The nonparametric function is estimated by a robust penalized smoothing method. The penalty term is defined with the parametric ODE model, which controls the roughness of the nonparametric function and maintains the fidelity of the nonparametric function to the ODE model. The basis coefficients and ODE parameters are estimated in two nested levels of optimization. The coefficient estimates are treated as an implicit function of ODE parameters, which enables one to derive the analytic gradients for optimization using the implicit function theorem. Simulation studies show that the robust method gives satisfactory estimates for the ODE parameters from noisy data with outliers. The robust method is demonstrated by estimating a predator-prey ODE model from real ecological data.

Real-time imaging and detection of intracranial haemorrhage by electrical impedance tomography in a piglet model

The aim of this study was to use electrical impedance tomography (EIT) to detect and image acute intracranial haemorrhage (ICH) in an animal model. Blood was infused into the frontal lobe of the brains of anaesthetized piglets and impedance was measured using 16 electrodes placed in a circle on the scalp. The EIT images were constructed using a filtered back-projection algorithm. The mean of all the pixel intensities within a region of interest--the mean resistivity value (MRV)--was used to evaluate the relative impedance changes in the target region. A symmetrical index (SI), reflecting the relative impedance on both sides of the brain, was also calculated. Changes in MRV and SI were associated with the injection of blood, demonstrating that EIT can successfully detect ICH in this animal model. The unique features of EIT may be beneficial for diagnosing ICH early in patients after cranial surgery, thereby reducing the risk of complications and mortality.

A mathematical model of human thymidine kinase 2 activity

The mitochondrial enzyme thymidine kinase 2 (TK2) phosphorylates deoxythymidine (dT) and deoxycytidine (dC) to form dTMP and dCMP, which in cells rapidly become the negative-feedback end-products dTTP and dCTP. TK2 kinetic activity exhibits Hill coefficients of ∼0.5 (apparent negative cooperativity) for dT and ∼1 for dC. We present a mathematical model of TK2 activity that is applicable if TK2 exists as two monomer forms in equilibrium.

Effects of cyclic AMP on development and secondary metabolites of Monascus ruber M-7

AIM

To study effects of cyclic adenosine monophosphate (cAMP) on development and secondary metabolites of Monascus ruber M-7.

METHODS AND RESULTS

Plate culture, liquid-state fermentation (LSF) and solid-state fermentation (SSF) were used to evaluate effects of cAMP on colonial growth, spore formation and polyketide production of Strain M-7. The results revealed that the variation trends of colonial sizes, numbers of sexual spores and red pigment contents of M-7 were in a dose-dependent manner. And generally they increased and decreased with cAMP concentrations in the ranges of low cAMP concentrations and high cAMP concentrations, respectively. But the variation trends of numbers of asexual spores and citrinin production in both LSF and SSF were opposite to those of colonial sizes, sexual sporulation and red pigment.

CONCLUSIONS

The regulation of cAMP on development and secondary metabolites in Strain M-7 was in a dose-dependent pattern. And red pigment might convert to citrinin under changing cAMP concentrations.

SIGNIFICANCE AND IMPACT OF THE STUDY

The effects of cAMP on Strain M-7 in SSF give a new clue to enhance beneficial polyketides and reduce citrinin produced by M. ruber.

Percutaneous sclerotherapy of massive macrocystic lymphatic malformations of the face and neck using fibrin glue with OK-432 and bleomycin

Picibanil (OK-432) and bleomycin have been used as alternative sclerosing agents for lymphatic malformations. This study evaluated the clinical curative effect of sclerotherapy using fibrin glue combined with OK-432 and bleomycin for the treatment of macrocystic lymphatic malformations of the face and neck. Fifteen paediatric patients (6 males; 9 females, aged 13 months to 14 years) who had received percutaneous sclerotherapy for massive macrocystic lymphatic malformations of the face and neck were retrospectively reviewed. Affected regions included the neck, parotid region and parapharynx, mouth floor, face and cheek, and orbital regions. All patients showed preoperative symptoms of space-occupying lesions between 4 cm × 5 cm and 12 cm × 16 cm in size. Fibrin glue with OK-432 and bleomycin was injected under general anaesthesia. All patients received preoperative and follow-up CT scans. Outcomes were assessed by three surgeons. All patients exhibited mid-facial swelling for 3-4 weeks after surgery, but no major complications. Follow-up periods ranged from 8 to 16 months. Eight lesions were completely involuted, five were mostly involuted, and two were partially involuted. Percutaneous sclerotherapy using fibrin glue with OK-432 and bleomycin provided a simple, safe, and reliable alternative treatment for massive macrocystic lymphatic malformations of the face and neck.

Large exchange bias after zero-field cooling from an unmagnetized state

Exchange bias (EB) is usually observed in systems with an interface between different magnetic phases after field cooling. Here we report an unusual phenomenon in which a large EB can be observed in Ni-Mn-In bulk alloys after zero-field cooling from an unmagnetized state. We propose that this is related to the newly formed interface between different magnetic phases during the initial magnetization process. The magnetic unidirectional anisotropy, which is the origin of the EB effect, can be created isothermally below the blocking temperature.

Behaviour of Zirconia Based Fuel Material Under Xe Irradiation

The behaviour of ZrO2-10%YO1.5-5%ErO1.5-( 10%ThO2) (At %) cubic solid solutions under low and high energy Xe ion irradiation up to a fluence of 1.8·1016 Xe.cm−2 was investigated by TEM. Low energy (60 keV) Xe ions did not yield amorphization. From the observed bubble formation, swelling values of less than one volume per cent were estimated to be 0.19–0.72% during irradiation at room temperature or at high temperature (925 K). Furthermore, no amorphization was obtained by Xe irradiation under extreme conditions such as high energy (1.5 MeV) Xe ion and low temperature (20 K). This confirms the robustness of this material and argues in favour of the selection of zirconia based material as an advanced nuclear fuel for plutonium disposition.

Role of matrix metalloproteinase-8 in the modulation of systemic 5-fluorouracil pharmacokinetics by local irradiation

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Background: Concurrent chemoradiation with 5-fluorouracil (5-FU) is widely accepted for cancer treatment. However, the interactions between radiation and 5-FU remain unclear. We evaluated the influence of local irradiation on the pharmacokinetics of 5-FU in rats.

Methods: The single-fraction radiation was delivered to the whole pelvic fields of Sprague-Dawley rats from a linear accelerator after computerized tomography-based planning. 5-FU at 100 mg/kg was intravenously infused 24 hours after radiation. A high-performance liquid chromatography system equipped with a UV detector was used to measure 5-FU in the blood. Matrix metalloproteinase-8 (MMP-8) inhibitor I was administered to the rats to examine whether or not RT modulation of 5-FU pharmacokinetic parameters could be blocked.

Results: Compared with sham-irradiated controls, whole pelvic irradiation reduced the area under the concentration versus time curve (AUC) of 5-FU in plasma and, in contrast, increased the AUC in bile in a radiation dose-dependent manner. Based on protein array analysis, the amount of plasma MMP-8 was increased by whole pelvic irradiation (2.8-fold by 0.5 Gy and 5.3-fold by 2 Gy) in comparison with controls. Pretreatment with MMP-8 inhibitor reversed the effect of irradiation on AUC of 5-FU in plasma.

Conclusions: Local irradiation may modulate the systemic pharmacokinetics of 5-FU through stimulating the release of MMP-8. This unexpected influence is worthy of further investigation and for consideration in clinical practice of radiotherapy for cancer.

No significant financial relationships to disclose.

Concurrent chemoradiotherapy for unresectable hilar choloangiocarcinoma: A single-institution experience

326

Background: Hilar cholangiocarinoma (Klatskin tumor) is a rare malignancy which is best managed with surgical resection. The majority of patients, however, is unresectable at the time of diagnosis and generally has a poor outcome. The purpose of this study was to retrospectively evaluate the role of chemoradiotherapy (CCRT) for patients with unresectable hilar choloangiocarcinoma at a single institution.

Methods: Between 2001 and 2008, a total of 33 patients with unresectable, nonmetastatic hilar cholangiocarcinoma treated at Taipei Veterans General Hospital were reviewed. All patients were to receive 3D-CRT with a median dose of 50.4 Gy (range, 39.6- 60) at 1.8-2 Gy per fraction per day. Sixteen patients also received bolus 5-fluorouracil (5-FU) CCRT (500 mg/m2/d for 3 days repeated every 2 weeks during radiotherapy for 6 weeks). Survivals were estimated by the Kaplan-Meier method and compared by log-rank test.

Results: There were 21 males and 12 females, with a median age of 71 years (range, 29 - 81). The median follow-up time was 10.4 months (range, 1 – 42.3) for all patients with the 1- and 2-year survival rates of 45% and 12%, respectively. The median overall survival (OS) and progression-free survival (PFS) were 13.5 months and 10.2 months for the CCRT group, and 10.4 months and 6.5 months for the RT alone group (p = 0.36 and p = 0.28, respectively). Adverse events were similar in thetwo groups with 14 patients (42%) developed grade 1-2 gastrointestinal toxicity during RT. Locoregional progression was observed in 26 patients (79%) and distant metastases in 9 patients (27%). All patients experienced disease progression and had died at time of analysis.

Conclusions: The outcome remains poor for unresectable hilar cholangiocarcinoma despite aggressive combined modality treatment. Although not statistically significant, our data showed CCRT provides longer OS and PFS in patients with unresectable hilar cholangiocarcinoma compared to RT alone. Locoregional progression is the main problem for this disease and the efficacy of adding chemotherapy or biologic agents needs to be further investigated.

No significant financial relationships to disclose.

Survival by anatomic site, histologic type, and tumor stage in stomach and esophageal cancer patients from the U.S. SEER Cancer Registry

28

Background: Data on the association of tumor characteristics and survival for stomach cancer (SC) and esophageal cancer (EC) patients (pts) are limited. The objective of this study was to describe survival in United States. SC and EC pts by anatomic site, histologic type, and tumor stage.

Methods: SC and EC pts were identified in the Surveillance, Epidemiology and End Results (SEER) Cancer Registry. SC was classified by anatomic site (cardia and non-cardia/other) and histologic type (intestinal, diffuse, other per Lauren criteria). EC was classified into anatomic site (middle/upper third, abdominal/lower third, overlapping lesions, NOS) and histologic type (adenocarcinoma (AC), squamous cell carcinoma (SQ), other). Frequency distribution and median survival were examined in these subgroups.

Results: From 2004-2006, >15,500 SC and > 9,800 EC cases were diagnosed. SC: (29% cardia) and (24% diffuse, 66% intestinal, 10% other). Compared with non-cardia/other pts, cardia pts tended to be male (77% vs 56%), white (88% vs 66%), intestinal type (77% vs 61%) and present with earlier stage disease (stage I-IIIa: 48% vs 42%). With the exception of stage I/II pts, survival was longer in cardia than non-cardia/other pts. The difference was most striking in stage IIIb/IV pts (7 months (mos) cardia vs 4 mos non-cardia/other). Compared to intestinal type, diffuse type tended to be younger (median age: 64 vs 72 yrs), more female (49% vs 34%), and present with more stage IIIb/IV disease (50% vs 39%). No difference in survival by histologic type was observed when accounting for stage. EC: (26% middle/upper, 58% lower, 5% overlapping, 11% NOS) and (57% AC, 34% SQ, 9% other). Among pts with AC histology 78% occurred in the lower third; in SQ most occurred in upper/middle third (56%). Compared to SQ, AC tended to be male (85% vs 63%), white (95% vs 67%), and present with stage IV disease (34% vs 25%). For all stages combined, survival was longer for AC pts (11 mos AC, 9 mos SQ, 4 mos other). This difference was most apparent among early stage (I-III) pts.

Conclusions: Survival in SC and EC was associated with staging, anatomic and histologic subtypes. Quantifying this provides insights for the design and interpretation of clinical development programs.

[Table: see text]

Factors associated with occupational strain among Chinese teachers: a cross-sectional study

OBJECTIVES

With the reform of the education system in China, teachers are suffering from more occupational strain, which is believed to impair their working state indirectly and affect their health. This study assessed occupational strain and explored the related factors among Chinese teachers.

STUDY DESIGN

Cross-sectional with cluster sampling.

METHODS

The study population was composed of 3570 school teachers working in 64 primary and middle schools in Heping District in Shenyang, China. Data were collected using a self-administered questionnaire (the Chinese version of the Occupational Stress Inventory scale). Multivariate linear regression analyses were performed to study the factors related to occupational strain.

RESULTS

The average score on the Personal Strain Questionnaire (PSQ) for the whole study population was 106.5 (107.5 in men and 106.3 in women). Teachers with chronic disease, a greater number of days of sick leave, recent experience of a stressful life event and divorced/separated/widowed status tended to suffer greater strain than their peers. Regression analyses showed that the PSQ score was significantly associated with role overload, role boundary, responsibility and physical environment, and inversely associated with recreation and rational coping. The most crucial predictors of occupational strain were chronic disease, days of sick leave, recent experience of a stressful life event and marital status. Being a class teacher was the strongest indicator of interpersonal strain. Self-care was associated with vocational strain and psychological strain, and inversely associated with physical strain.

CONCLUSIONS

Most teachers in this study experienced a high degree of occupational strain. Chronic disease, days of sick leave, recent experience of a stressful life event and divorced/separated/widowed status played prominent roles in occupational strain. In addition, role overload, role boundary, responsibility and physical environment induce occupational strain, while recreation and rational coping have a positive effect on occupational strain. Interventions such as proper management of chronic diseases and establishment of a balanced work-family life are crucial to reduce occupational strain. Recreation and training in coping abilities are needed to enhance positive working environments and attenuate the occupational strain imposed on teachers.

A predictive value of hyponatremia for poor outcome and cerebral infarction in high-grade aneurysmal subarachnoid haemorrhage patients

BACKGROUND

The clinical significance of hyponatremia has not been investigated in high-grade aneurysmal subarachnoid haemorrhage (aSAH) patients. Thus, we assessed the predictive value of hyponatremia for poor outcome or cerebral infarction in high grade patients (the World Federation of Neurological Surgeons Scale (WFNS) grade 4 or 5) after aSAH.

METHODS

Patients with WFNS grade 4 or 5 after aSAH were selected into this study between January 2005 and January 2008. In the same period, patients with WFNS grade 1, 2 or 3 after aSAH (low grade) were also chosen into this study. Hyponatremia was determined with serum sodium measurements obtained within 9 days after aSAH. Prognosis of patients was estimated with Glasgow Outcome Scale at 3 months. The relationship between hyponatremia and poor outcome and association of hyponatremia and cerebral infarction were analysed, respectively.

RESULTS

A total of 124 high-grade patients were included in this study. Of those, 78 patients developed hyponatremia. Hyponatremia developed in 32.3% of cases between days 1 and 3 after aSAH, and 30.6% developed hyponatremia after 3 days post-aSAH. Multivariable analysis revealed that hyponatremia was not correlated with poor outcome in high-grade aSAH patients. Furthermore, only late-onset hyponatremia was correlated with cerebral infarction in these patients. Meanwhile, there was no significant correlation between hyponatremia and poor outcome or cerebral infarction in 259 low-grade aSAH patients.

CONCLUSIONS

Hyponatremia does not predict poor outcome in all-grade aSAH patients. However, late-onset hyponatremia in high-grade aSAH patients is associated with cerebral infarction. Therefore, the appropriate management of hyponatremia could be beneficial in those patients.

The optimum number of retrieved lymph nodes for locally advanced rectal cancer following short-course preoperative radiotherapy: A study by fat clearance

449

Background: The optimum number of retrieved lymph nodes following preoperative radiotherapy and surgery for locally advanced rectal cancer is still controversial. This study is designed to confirm the least number of retrieved lymph nodes for locally advanced rectal cancer following 30Gy/10f short-course preoperative radiotherapy.

Methods: From Aug 2002 to Mar 2010, two hundred and twelve patients with locally advanced rectal cancer received 30Gy/10f preoperative radiotherapy (BED: 36Gy), standardized total mesorectal excision and fat-clearance based pathological evaluation in Beijing Cancer Hospital. The size of retrieved lymph nodes (LNs) was recorded. The sequence of LNs was arranged by a descending sort by retrieved nodes' size and the serial number of the largest metastatic lymph node (mLN) was recorded. The serial number of the first largest mLN is regarded as the least number of LNs to distinguish ypN+ status. The cumulative accuracy of ypN stage by variable numbers of LNs was calculated and analyzed.

Results: There were total 4,669 retrieved LNs and 354 mLNs. The median retrieved LNs number was 21 (range 4-61). The ypN positive rate was 40.6%. The peak-value of quantitive distribution of LNs and mLNs was observed in 1-2mm and 3-4mm level. The incidence of retrieving mLNs shows an intensifying tendency for increasing size of LNs. The analysis for sequence of LNs sorting suggested that 85.4% of cases could confirm their ypN stage by the first largest LN. The cumulative accuracy ascended to 95.1% or 98.1% when the first 5 or 9 largest LNs were retrieved.

Conclusions: For rectal cancer following 30Gy/10f preoperative radiotherapy, retrieving 12 or more lymph nodes seems not to be mandatory for confirming ypN stage. The accuracy in confirming negative ypN stage when retrieving 5 or 9 largest nodes is sufficient for majority of patients. In those cases that could not retrieve 5 or more nodes by routine fixation, fat clearance is indispensable.

No significant financial relationships to disclose.

Identification of potential surrogate end points in randomized clinical trials of aggressive and indolent non-Hodgkin's lymphoma: correlation of complete response, time-to-event and overall survival end points

BACKGROUND

The correlation between efficacy end points in randomized controlled trials (RCTs) of systemic therapy for non-Hodgkin's lymphoma (NHL) was investigated to identify an appropriate surrogate end point for overall survival (OS).

METHODS

RCTs of previously untreated NHL published from 1990 to 2009 were identified. Associations between absolute differences in efficacy end points were determined using nonparametric Spearman's rank correlation coefficients (r(s)).

RESULTS

Thirty-eight RCTs representing 85 treatment arms for aggressive NHL and 20 RCTs representing 42 arms for indolent NHL were included. For aggressive NHL, differences in 3-year progression-free survival (PFS)/event-free survival (EFS) were high correlated with differences in 5-year OS {r(s) of 0.90 [95% confidence interval (CI) 0.73-0.96]} and linear regression determined that a 10% improvement in 3-year EFS or PFS would predict for a 7% ± 1% improvement in 5-year OS. For indolent histology disease, differences in complete response were strongly correlated with differences in 3-year EFS [r(s) 0.86 (95% CI 0.35-0.97)], but there was no correlation between 3-year time-to-event end points and 5-year OS.

CONCLUSIONS

Improvements in 3-year EFS/PFS are highly correlated with improvements in 5-year OS in aggressive NHL and should be explored as a candidate surrogate end point. Definition of these relationships may inform future clinical trial design and interpretation of interim trial data.

A morphological study of corneal flap after thin-flap laser-assisted in situ keratomileusis by anterior segment optical coherence tomography

This prospective study assessed corneal flap morphology in 115 patients undergoing laser-assisted in situ keratomileusis (LASIK). Flaps were created using the Moria M2 90-μm or KM-5000D 110-μm microkeratomes. Flap thickness was measured using anterior segment optical coherence tomography at seven points in a 7-mm diameter zone 1 h, 1 day, 3 days, 1 week and 1 month after surgery. Flap accuracy, reproducibility, uniformity and changes over time were evaluated. The Moria M2 microkeratome created flaps with less accuracy in the centre than the KM-5000D microkeratome (114.06 ± 6.46 μm vs 128.39 ± 6.79 μm, respectively, at 1 week). For both microkeratomes, flap thickness varied between most of the peripheral areas and the central point. Both microkeratomes created flaps with good central predictability and reproducibility, but high variation and significant deviation from intended thickness were observed in peripheral flap thickness.