Physcion inhibition of CYP2C9, 2D6 and 3A4 in human liver microsomes

CONTEXT

The effect of the active ingredients in traditional Chinese medicines on the activity of cytochrome P450 enzymes (CYP450s) is a critical factor that should be considered in TCM prescriptions. Physcion, the major active ingredient of Rheum spp. (Polygonaceae), possesses wide pharmacological activities.

OBJECTIVES

The effect of physcion on CYP450 activity was investigated to provide a theoretical basis for use.

MATERIALS AND METHODS

The experiments were conducted in pooled human liver microsomes (HLMs). The activity of CYP450 isoforms was evaluated with corresponding substrates and probe reactions. Blank HLMs were set as negative controls, and typical inhibitors were employed as positive controls. The inhibition model was fitted with Lineweaver Burk plots. The concentration (0, 2.5, 5, 10, 25, 50 and 100 μM physcion) and time-dependent (0, 5, 10, 15 and 30 min) effects of physcion were also assessed.

RESULTS

Physcion suppressed CYP2C9, 2D6 and 3A4 in a concentration-dependent manner with IC50 values of 7.44, 17.84 and 13.50 μM, respectively. The inhibition of CYP2C9 and 2D6 was competitive with the Ki values of 3.69 and 8.66 μM, respectively. The inhibition of CYP3A4 was non-competitive with a Ki value of 6.70 μM. Additionally, only the inhibition of CYP3A4 was time-dependent with the KI and Kinact parameters of 3.10 μM-1 and 0.049 min-1, respectively.

CONCLUSIONS

The inhibition of CYP450s by physcion should be considered in its clinical prescription, and the study design can be employed to evaluate the interaction of CYP450s with other herbs.

Clinical prediction models in children that use repeated measurements with time-varying covariates: a scoping review

BACKGROUND

Emerging evidence suggests that clinical prediction models that use repeated (time-varying) measurements within each patient may have higher predictive accuracy than models that use patient information from a single measurement.

OBJECTIVE

To determine the breadth of the published literature reporting the development of clinical prediction models in children that use time-varying predictors.

DATA SOURCES

MEDLINE, EMBASE and Cochrane databases.

ELIGIBILITY CRITERIA

We included studies reporting the development of a multivariable clinical prediction model in children, with or without validation, to predict a repeatedly measured binary or time-to-event outcome and utilizing at least one repeatedly measured predictor.

SYNTHESIS METHODS

We categorized included studies by the method used to model time-varying predictors.

RESULTS

Of 99 clinical prediction model studies that had a repeated measurements data structure, only 27 (27%) used methods that incorporated the repeated measurements as time-varying predictors in a single model. Among these 27 time-varying prediction model studies, we grouped model types into nine categories: time-dependent Cox regression, generalized estimating equations, random effects model, landmark model, joint model, neural network, K-nearest neighbor, support vector machine and tree-based algorithms. Where there was comparison of time-varying models to single measurement models, using time-varying predictors improved predictive accuracy.

CONCLUSIONS

Various methods have been used to develop time-varying prediction models in children, but there is a paucity of pediatric time-varying models in the literature. Incorporating time-varying covariates in pediatric prediction models may improve predictive accuracy. Future research in pediatric prediction model development should further investigate whether incorporation of time-varying covariates improves predictive accuracy.

Formulation and optimization of a single-layer coat for targeting budesonide pellets to the descending Colon

The current budesonide formulations are inadequate for addressing left-sided colitis, and patients might hesitate to use an enema for a prolonged time. This study focuses on developing a single-layer coating for budesonide pellets targeting the descending colon. Pellets containing budesonide (1.5%w/w), PVP K30 (5%w/w), lactose monohydrate (25%w/w) and Avicel pH 102 (68.5%w/w) were prepared using extrusion spheronization technique. Coating formulations were designed using response surface methodology with pH and time-dependent Eudragits. Dissolution tests were conducted at different pH levels (1.2, 6.5, 6.8, and 7.2). Optimal coating formulation, considering coating level and the Eudragit (S + L) ratio to the total coating weight, was determined. Budesonide pellets were coated with the optimized composition and subjected to continuous dissolution testing simulating the gastrointestinal tract. The coating, with 48% S, 12% L, and 40% RS at a 10% coating level, demonstrated superior budesonide delivery to the descending colon. Coated pellets had a spherical shape with a uniform 30 µm thickness coating, exhibiting pH and time-dependent release. Notably, zero-order release kinetics was observed for the last 9 h in colonic conditions. The study suggests that an optimized single-layer coating, incorporating pH and time-dependent polymers, holds promise for consistently delivering budesonide to the descending colon.

Comprehensive Study on the Ion-Selective Behavior of MnOx for Electrochemical Deionization

Manganese oxide is an effective active material in several electrochemical systems, including batteries, supercapacitors, and electrochemical deionization (ECDI). This work conducts a comprehensive study on the ion-selective behavior of MnOx to fulfill the emptiness in the energy and environmental science field. Furthermore, it broadens the promising application of MnOx in the ion-selective ECDI system. We propose a time-dependent multimechanism ion-selective behavior with the following guidelines by utilizing a microfluidic cell and the electrochemical quartz crystal microbalance (EQCM) analysis. (1) Hydrated radius is the most critical factor for ions with the same valence, and MnOx tends to capture cations with a small hydrated radius. (2) The importance of charge density rises when comparing cations with different valences, and MnOx prefers to capture divalent cations with a strong electrostatic attraction at prolonged times. Under this circumstance, ion swapping may occur where divalent cations replace monovalent cations. (3) NH4+ triggers MnOx dissolution, leading to performance and stability decay. The EQCM evidence has directly verified the proposed mechanisms, and these data provide a novel but simple method to judge ion selectivity preference. The overall ion selectivity sequence is Ca2+ > Mg2+ > K+ > NH4+> Na+ > Li+ with the highest selectivity values of βCa//Li and βCa//Na around 3 at the deionization time = 10 min.

Non-Selective Beta-Blockers and Risk of Sepsis in Patients with Cirrhosis and Ascites: Results from a Large Observational Study

Background and Aims

Previous studies have not been able to determine whether non-selective beta-blockers (NSBB) reduce the risk of sepsis in cirrhosis. We aimed to examine this question with data from 1198 patients with cirrhosis and ascites included in clinical studies of satavaptan, a vasopressin receptor antagonist with no effect on infection risk.

Methods

Risk of sepsis was estimated for NSBB users vs nonusers. Patients were examined every four weeks, or in relation to hospitalization, for the one-year duration of the trials. We computed the cumulative risk of sepsis for patients who did vs did not use NSBB at baseline. We used Cox regression to compare hazard rates of sepsis between current users and nonusers, accounting for changes in NSBB use over time. We adjusted for patient sex and age, MELD-Na score, albumin, use of antibiotics, use of proton pump inhibitors, cirrhosis etiology, history of variceal bleeding or SBP, severity of ascites and HE, HCC, other cancers, and diabetes, while stratifying on geographical region.

Results

Of the 1198 patients, 54% used NSBB at some time. There were 56 sepsis episodes. The 1-year risk of sepsis was reduced to 5.7% (95% confidence interval [CI] 2.8-8.6) in baseline NSBB users vs 11.6% (95% CI 7.0-15.9) in baseline nonusers. The hazard ratio of sepsis for current NSBB users vs current nonusers was reduced to 0.5 (95% CI 0.3-0.8) and after adjustment to 0.7 (95% CI 0.4-1.3).

Conclusion

NSBB use may reduce the risk of sepsis in patients with cirrhosis and ascites, but the precision of the estimate was limited by the number of episodes of sepsis.

Sorption and Desorption of Vapor of n-Pentane by Porphyrin Aluminum Metal-Organic Framework: Mechanism of Bonding, Kinetics and Stoichiometry by Complementary In-Situ Time-Dependent and Ex-Situ Methods

Metal-organic frameworks (MOFs) are highly nanostructured coordination polymers that contain metal cations and organic linkers and feature very large pore volumes and surface areas. The sorption and desorption of n-pentane vapor by porphyrin aluminum metal-organic framework Al-MOF-TCPPH₂ where TCPPH₂ is tetrakis(4-carboxyphenyl)porphyrin linker were studied by a novel method of in-situ time-dependent attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy in a controlled atmosphere and complementary in-situ and ex-situ methods. Sorption facilely occurs in the flow of dried air, and in the obtained adsorption complex the adsorbate molecules interact with phenyl and carboxylate groups of the linker and the O-H group. Sorption kinetics follows the pseudo-first-order rate law, as confirmed by in-situ time-dependent gravimetry. Further, an ex-situ (static) sorption of n-pentane vapor results in an adsorption complex with as much as 29.1 wt.% n-pentane with the stoichiometric formula [Al-MOF-TCPPH₂]₂(n-C₅H₁₂)₇ and a distinct XRD pattern. Finally, in the flow of dried air, the adsorption complex gradually desorbed n-pentane, following the pseudo-first-order rate law. The reversibility of sorption and desorption makes porphyrin aluminum MOF promising for the separation of light hydrocarbons and chemo-sensing. In-situ time-dependent ATR-FTIR spectroscopy in a controlled atmosphere, in combination with in-situ time-dependent gravimetry, is a new approach for the determination of binding sites of sorbents with adsorbate molecules, the stoichiometry of complexes, and chemical kinetics of "solid-gas" interactions.

The inhibitory effects of pimozide, an antipsychotic drug, on voltage-gated K+ channels in rabbit coronary arterial smooth muscle cells

Pimozide is an antipsychotic drug used to treat chronic psychosis, such as Tourette's syndrome. Despite its widespread clinical use, pimozide can cause unexpected adverse effects, including arrhythmias. However, the adverse effects of pimozide on vascular K⁺ channels have not yet been determined. Therefore, we investigated the effects of pimozide on voltage-gated K⁺ (Kv) channels in rabbit coronary arterial smooth muscle cells. Pimozide concentration-dependently inhibited the Kv currents with an IC₅₀ value of 1.78 ± 0.17 μM and a Hill coefficient of 0.90 ± 0.05. The inhibitory effect on the Kv current by pimozide was highly voltage-dependent in the voltage range of Kv channel activation, and additive inhibition of the Kv current by pimozide was observed in the full activation voltage range. The decay rate of inactivation was significantly accelerated by pimozide. Pimozide shifted the inactivation curve to a more negative potential. The recovery time constant from inactivation increased in the presence of pimozide. Furthermore, pimozide-induced inhibition of the Kv current was augmented by applying train pulses. Although pretreatment with the Kv2.1 subtype inhibitor guangxitoxin and the Kv7 subtype inhibitor linopirdine did not alter the degree of pimozide-induced inhibition of the Kv currents, pretreatment with the Kv1.5 channel inhibitor DPO-1 reduced the inhibitory effects of pimozide on Kv currents. Pimozide induced membrane depolarization. We conclude that pimozide inhibits Kv currents in voltage-, time-, and use (state)-dependent manners. Furthermore, the major Kv channel target of pimozide is the Kv1.5 channel.

Time-dependent changes in RPILD and mortality risk in anti-MDA5+ DM patients: a cohort study of 272 cases in China

OBJECTIVES

Anti-melanoma differentiation-associated gene 5 positive (anti-MDA5+) DM has a close relationship with rapidly progressive interstitial lung disease (RPILD) and is associated with high mortality. However, data regarding the time-dependent risk of RPILD and deaths during disease progression are limited. We conducted this study to investigate whether the risk of RPILD and death were time-dependent or not in anti-MDA5+ DM.

METHODS

We assessed a cohort of 272 patients with anti-MDA5+ DM. The clinical characteristics of patients with anti-MDA5+ were collected, and COX regression was used to analyse independent risk factors for RPILD and death. We also described changes in risk of RPILD and death over time and their potential clinical implications.

RESULTS

There were 272 anti-MDA5+ DM patients enrolled in this study. According to the multivariate cox regression analysis, short disease course, high CRP level, anti-Ro52 positive and anti-MDA5 titre (++∼+++) were independent risk factors of RPILD. High creatine kinase level, high CRP level and RPILD were independent risk factors for death, and >90% RPILD and 84% mortality occurred in the first 6 months after disease onset. Notably, the first 3 months is a particularly high-risk period, with 50% of RPILD and 46% of deaths occurring. Hazards regarding RPILD and mortality diminished over time during a median follow-up of 12 months.

CONCLUSION

These results suggest significant, time-dependent changes in RPILD and mortality risk in anti-MDA5+ DM patients, providing a cut-off time window to estimate disease progression and poor prognosis.

In Situ Time-Dependent Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy of a Powdered Specimen in a Controlled Atmosphere: Monitoring Sorption and Desorption of Water Vapor

Attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy is a powerful instrumental method of chemical analysis of solids and liquids. The majority of published studies by in situ ATR FT-IR spectroscopy describe analysis of homogeneous samples, such as liquid solutions under circulation, or films on the ATR crystal that react with the gas of interest. The in situ ATR FT-IR spectroscopic studies of specimens in physical shape of crystals or powder that react with a gas or vapor are rare. This work describes a modification of in situ time-dependent ATR FT-IR spectroscopy to allow monitoring heterogeneous reaction "solid-gas" of powder in controlled atmosphere and in the time domain. Also, we describe a new facile gas flow chamber attachment to ATR FT-IR spectrometer which allows creating controlled atmosphere surrounding the specimen on the ATR crystal. Additionally, the capabilities of the described in situ time-dependent ATR FT-IR spectroscopy experiment in controlled atmosphere are enhanced by the sensor for in situ time-dependent monitoring the relative humidity (RH) of air surrounding the specimen. The operation of the setup for in situ time-dependent ATR FT-IR spectroscopy in controlled atmosphere is demonstrated by monitoring reaction of gradual desorption of water vapor from color-indicating molecular sieves under controlled low air humidity. Further, the described spectroscopic method and apparatus is applied to monitor the reverse process, namely sorption of water vapor by color-indicating molecular sieves under controlled elevated air humidity. Water molecules are found to reversibly interact with two distinct sorption sites in the sorbent: the Si-O backbone and the color-indicating Co(II) centers. The reported variant of in situ time-dependent ATR FT-IR spectroscopy in controlled atmosphere is powerful, yet facile and straightforward. It is promising for mechanistic, in situ studies of sorption, desorption, chemosensing, heterogeneous catalysis and photocatalysis, and analysis of chemical kinetics of various "solid-gas" reactions.

Comparative Bioavailability and Benefits on Mental Functions of Novel Extended-Release Caffeine Capsules against Immediate-Release Caffeine Capsules: An Open-Label, Randomized, Cross-over, Single-Dose Two-Way Crossover Study

Present study aimed compared pharmacokinetic profile of sustained-release CaffXtend® capsules (SR-Caffeine) with immediate-release caffeine capsules (IR-Caffeine), and the effect of SR-caffeine on memory, motivation, concentration, and attention. This open-label, randomized, single-dose, two-treatment, two-sequence, two-period, two-way crossover oral bioavailability study block randomized (1:1) healthy subjects (N = 15) to receive SR-Caffeine (200 mg) and IR-Caffeine (200 mg). Blood samples were collected at 0.25, 0.50, 0.75, 1, 1.5, 2, 3, 4, 5, 6, 8, 10, 12, 24, 36 and 48 h in each period. Primary study outcome included comparing relative bioavailability of SR-Caffeine 200 mg and IR-Caffeine 200 mg under fasting conditions, and changes in caffeine research visual analogue scale (Caff-VAS) scores ('relaxed', 'alert', 'jittery', 'tired', 'tense', 'headache', 'overall mood' and 'mentally fatigued') were also evaluated. Fifteen subjects completed the study. Mean tmax was 4.08 ± 2.13h for SR-Caffeine compared to 0.83 ± 0.39h for IR-Caffeine, (p < 0.0001). Similarly, mean t½ was 7.07 ± 3.48h for SR-Caffeine compared to 5.78 ± 2.11h for IR-Caffeine (p = 0.04189). However, total exposure was similar for SR-Caffeine and IR-Caffeine (90% CI: 89.89-120.50% to 94.49-123.82% for geometric least square mean of ln-transformed AUC0-t and AUC0-∞). In the Caff-VAS evaluation, the SR-Caffeine group showed significantly better scores for 'jitteriness', 'tiredness', 'alertness' and 'overall mood' for 8-12 h than the IR-Caffeine group. No adverse events were reported. Results demonstrated sustained release of caffeine over 24 h from SR-Caffeine as compared to IR-Caffeine, which showed significant improvements in the scores for 'relaxed', 'alertness' and 'overall mood' and significantly lower scores for the parameters-'jittery' and 'tired' for extended period.Clinical trial registration: CTRI/2021/06/034185.

A Tutorial on Time-Dependent Cohort State-Transition Models in R Using a Cost-Effectiveness Analysis Example

In an introductory tutorial, we illustrated building cohort state-transition models (cSTMs) in R, where the state transition probabilities were constant over time. However, in practice, many cSTMs require transitions, rewards, or both to vary over time (time dependent). This tutorial illustrates adding 2 types of time dependence using a previously published cost-effectiveness analysis of multiple strategies as an example. The first is simulation-time dependence, which allows for the transition probabilities to vary as a function of time as measured since the start of the simulation (e.g., varying probability of death as the cohort ages). The second is state-residence time dependence, allowing for history by tracking the time spent in any particular health state using tunnel states. We use these time-dependent cSTMs to conduct cost-effectiveness and probabilistic sensitivity analyses. We also obtain various epidemiological outcomes of interest from the outputs generated from the cSTM, such as survival probability and disease prevalence, often used for model calibration and validation. We present the mathematical notation first, followed by the R code to execute the calculations. The full R code is provided in a public code repository for broader implementation.

A Comprehensive Dynamic Life Cycle Assessment Model: Considering Temporally and Spatially Dependent Variations

Life cycle assessment (LCA) is a widely-used international environmental evaluation and management method. However, the conventional LCA is in a static context without temporal and spatial variations considered, which fails to bring accurate evaluation values and hinders practical applications. Dynamic LCA research has developed vigorously in the past decade and become a hot topic. However, systematical analysis of spatiotemporal dynamic variations and comprehensive operable dynamic models are still lacking. This study follows LCA paradigm and incorporates time- and space-dependent variations to establish a spatiotemporal dynamic LCA model. The dynamic changes are classified into four types: dynamic foreground elementary flows, dynamic background system, dynamic characterization factors, and dynamic weighting factors. Their potential dynamics and possible quantification methods are analyzed. The dynamic LCA model is applied to a residential building, and significant differences can be observed between dynamic and static assessment results from both temporal and spatial perspectives. This study makes a theoretical contribution by establishing a comprehensive dynamic model with both temporal and spatial variations involved. It is expected to provide practical values for LCA practitioners and help with decision-making and environmental management.

A Calculation Method of Passenger Flow Distribution in Large-Scale Subway Network Based on Passenger-Train Matching Probability

The ever-increasing travel demand has brought great challenges to the organization, operation, and management of the subway system. An accurate estimation of passenger flow distribution can help subway operators design corresponding operation plans and strategies scientifically. Although some literature has studied the problem of passenger flow distribution by analyzing the passengers’ path choice behaviors based on AFC (automated fare collection) data, few studies focus on the passenger flow distribution while considering the passenger–train matching probability, which is the key problem of passenger flow distribution. Specifically, the existing methods have not been applied to practical large-scale subway networks due to the computational complexity. To fill this research gap, this paper analyzes the relationship between passenger travel behavior and train operation in the space and time dimension and formulates the passenger–train matching probability by using multi-source data including AFC, train timetables, and network topology. Then, a reverse derivation method, which can reduce the scale of possible train combinations for passengers, is proposed to improve the computational efficiency. Simultaneously, an estimation method of passenger flow distribution is presented based on the passenger–train matching probability. Finally, two sets of experiments, including an accuracy verification experiment based on synthetic data and a comparison experiment based on real data from the Beijing subway, are conducted to verify the effectiveness of the proposed method. The calculation results show that the proposed method has a good accuracy and computational efficiency for a large-scale subway network.

Evaluating the effectiveness of population-based breast cancer service screening: an analysis of parsimonious patient survival information with the time-varying Cox model

BACKGROUND

This study is aimed at estimating the unbiased effectiveness of population-based breast cancer service screening based on case survival information alone rather than large-scale individual screening data pursuant to the intention-to-treat principle of a randomized-controlled trial.

METHODS

A novel time-dependent switched design with two modalities of cancer detection (screen-detected vs clinically detected) was proposed to evaluate the effectiveness of breast cancer screening. We used data on 767 patients from Kopparberg in the Swedish Two-County trial and on 78 587 patients in the Taiwan population-based service screening. We estimated the relative rate of the screen-detected vs the clinically detected with adjustment for both truncation and lead-time biases. The absolute effectiveness in terms of the number needed to screen (NNS) for averting one death from breast cancer was estimated.

RESULTS

The relative rate of effectiveness was estimated as 33%, which was consistent with the 37% reported from the original Swedish randomized-controlled trial. The corresponding estimate for the Taiwan screening programme was 42%, which was also very close to that estimated using individual screening history data (41%). Both relative estimates were further applied to yield 446 and 806 of NNS for averting one death from breast cancer for the corresponding two data sets.

CONCLUSION

The proposed time-dependent switched design and analysis with two modalities of case survival information provides a very efficient means for estimating the unbiased estimates of relative and absolute effectiveness of population-based breast cancer service screening dispensing with a large amount of individual screening history data.

A Comparison of Amplitude-and Time-Dependent Cyclic Deformation Behavior for Fully-Austenite Stainless Steel 316L and Duplex Stainless Steel 2205

Austenite and duplex stainless steels are widely used in engineering, and the latter exhibits a more excellent combination of mechanical properties and corrosion resistance due to the coexistence of austenite and ferrite and higher nitrogen. However, fatigue failure still threatens their structural integrity. A comprehensive comparison of their cyclic deformation behavior is a major foundation to understand the role of duplex-phase microstructure and nitrogen in the safety assessment of engineering components. Thus, in this paper, the cyclic deformation behavior of fully-austenitic stainless steel 316L and duplex stainless steel 2205 was studied by a series of low cycle fatigue tests with various strain amplitudes, loading rates and tensile holding. A theoretical mechanism diagram of the interaction between nitrogen and dislocation movements during cyclic loads was proposed. Results show that the cyclic stress response of 2205 was the primary cyclic hardening, followed by a long-term cyclic softening regardless of strain amplitudes and rates, while an additional secondary hardening was observed for 316L at greater strain amplitudes. Cyclic softening of 2205 was restrained under slower strain rates or tensile holding due to the interaction between nitrogen and dislocations. The cyclic plasticity of 2205 started within the austenite, and gradually translated into the ferrite with the elevation of the cyclic amplitude, which lead to a decreased hardening ratio with the increase in amplitude and a shorter fatigue life for a given smaller plastic strain amplitude.

Time-Dependent Distribution of Hydroxychloroquine in Cynomolgus Macaques Using Population Pharmacokinetic Modeling Method

To evaluate the biodistribution of hydroxychloroquine (HCQ) in cynomolgus macaques and receive dynamic quantitative relationship between plasma, blood, and lung tissue concentration using the population pharmacokinetic modeling method, seventeen cynomolgus macaques were divided into six groups according to different HCQ dosing regimens over 5 days. The monkeys were euthanized, and blood, plasma, urine, feces and ten tissues were collected. All the samples were prepared by protein precipitation and analyzed by HPLC-MS/MS detection. The population pharmacokinetics of HCQ in the plasma, red blood cells, and lung tissue was conducted and simulated via ADAPT program. Results demonstrated that the maximum concentration (C max) of HCQ was 292.33 ng/mL in blood and 36.90 ng/mL in plasma after single dose of 3 mg/kg. The value of area under curve (AUC0-∞) was determined as 5,978.94 and 363.31 h* ng/mL for the blood and plasma, respectively. The descending order of the tissue-to-plasma concentration ratio was liver > spleen > kidney > lung > heart > subcutaneous fat > brain. The tissue-to-plasma concentration ratio and the tissue-to-blood concentration ratio for lung were found to be time-dependent with 267.38 and 5.55 at 120 h postdose, respectively. A five-compartment model with first-order oral absorption and elimination best described the plasma, blood, and lung tissue pharmacokinetics. The estimated elimination rate constant (ke) for a typical monkey was 0.236 h-1. The volume of distribution in central (Vc/F) and other two peripheral compartments (Vb/F and Vl/F) were 114, 2.68, and 5.55 L, respectively. Model-based simulation with PK parameters from cynomolgus macaques showed that the ratio of the blood or plasma to lung tissue was a dynamic change course, which suggested that the rate of HCQ concentration decrease in the blood or plasma was faster than that in the lung tissue. HCQ was found to be accumulated in tissues, especially in the liver, kidney, lung, and spleen. Also, the tissue-to-plasma concentration ratio increased over time. The population pharmacokinetic model developed could allow for the assessment of pharmacokinetics-pharmacodynamics relationships, especially relevant tissue concentration-response for HCQ. Determining appropriate treatment regimens in animals allows translation of these to clinical studies.

Role of time-normalized laboratory findings in predicting COVID-19 outcome

Objectives The pandemic COVID-19 currently reached 213 countries worldwide with nearly 9 million infected people and more than 460,000 deaths. Although several Chinese studies, describing the laboratory findings characteristics of this illness have been reported, European data are still scarce. Furthermore, previous studies often analyzed the averaged laboratory findings collected during the entire hospitalization period, whereas monitoring their time-dependent variations should give more reliable prognostic information. Methods We analyzed the time-dependent variations of 14 laboratory parameters in two groups of COVID-19 patients with, respectively, a positive (40 patients) or a poor (42 patients) outcome, admitted to the San Raffaele Hospital (Milan, Italy). We focused mainly on laboratory parameters that are routinely tested, thus, prognostic information would be readily available even in low-resource settings. Results Statistically significant differences between the two groups were observed for most of the laboratory findings analyzed. We showed that some parameters can be considered as early prognostic indicators whereas others exhibit statistically significant differences only at a later stage of the disease. Among them, earliest indicators were: platelets, lymphocytes, lactate dehydrogenase, creatinine, alanine aminotransferase, C-reactive protein, white blood cells and neutrophils. Conclusions This longitudinal study represents, to the best of our knowledge, the first study describing the laboratory characteristics of Italian COVID-19 patients on a normalized time-scale. The time-dependent prognostic value of the laboratory parameters analyzed in this study can be used by clinicians for the effective treatment of the patients and for the proper management of intensive care beds, which becomes a critical issue during the pandemic peaks.

Association between dynamic obesity and mortality in patients with first-ever ischemic stroke: A hospital-based prospective study

Although obesity is an established risk factor of primary stroke, the association between obesity and post-stroke mortality remains unclear. The aim of this study was to investigate the association between dynamic obesity status and mortality in survivors of their first stroke in China.Of 775 patients with first-ever ischemic stroke included in a longitudinal study, 754 patients were included in this study and categorized into 4 categories of body mass index (BMI) (underweight, normal weight, overweight, and obese) and 2 categories of waist circumference (WC) (normal WC and abdominal obesity) according to standard Chinese criteria. The mortality information and obesity status were obtained via telephone follow-up every 3 months, beginning in 2010 through 2016. Time-dependent Cox proportional hazards models were used to estimate the unadjusted and adjusted hazard ratios (HRs) for the relationship between all-cause mortality and dynamic obesity status.Of 754 patients, 60.87% were male, and the overall mean age was 61.45 years. After adjusting for possible confounders, significant inverse associations were identified between BMI and WC and all-cause mortality. Compared with those with normal BMI or WC, those with abdominal obesity or overweight had a significantly lower risk of all-cause mortality (HR and 95% confidence intervals [CIs]: .521 [.303-.897] and 0.545 [.352-.845], respectively), whereas patients with underweight had the highest risk and those with obesity had lower risk of mortality, though it was not statistically significant (1.241 [.691-2.226] and .486 [.192-1.231], respectively).Overweight and abdominal obesity were paradoxically associated with reduced risk of mortality in patients who survived their first-ever ischemic stroke in China. Future prospective studies must look at evaluating the role of obesity in different stroke subtypes and devise appropriate weight-management strategies for optimal prognoses in secondary prevention in these survivors.

Optimizing Antibiotic Treatment Strategies for Neonates and Children: Does Implementing Extended or Prolonged Infusion Provide any Advantage?

Optimizing the use of antibiotics has become mandatory, particularly for the pediatric population where limited options are currently available. Selecting the dosing strategy may improve overall outcomes and limit the further development of antimicrobial resistance. Time-dependent antibiotics optimize their free concentration above the minimal inhibitory concentration (MIC) when administered by continuous infusion, however evidences from literature are still insufficient to recommend its widespread adoption. The aim of this review is to assess the state-of-the-art of intermittent versus prolonged intravenous administration of antibiotics in children and neonates with bacterial infections. We identified and reviewed relevant literature by searching PubMed, from 1 January 1 2000 to 15 April 2020. We included studies comparing intermittent versus prolonged/continuous antibiotic infusion, among the pediatric population. Nine relevant articles were selected, including RCTs, prospective and retrospective studies focusing on different infusion strategies of vancomycin, piperacillin/tazobactam, ceftazidime, cefepime and meropenem in the pediatric population. Prolonged and continuous infusions of antibiotics showed a greater probability of target attainment as compared to intermittent infusion regimens, with generally good clinical outcomes and safety profiles, however its impact in terms on efficacy, feasibility and toxicity is still open, with few studies led on children and adult data not being fully extendable.

Familial risk of breast cancer by dynamic, accumulative, and static definitions of family history

BACKGROUND

Familial breast cancer risk studies usually overlook the dynamic nature of family history.

METHODS

The authors assessed the effect of incorporating the timing of cancer diagnosis events into the assessment of familial risks of breast cancer in first-degree and second-degree relatives in a nationwide cohort study of 5,099,172 women (follow-up was between 1958-2015). Family history was assessed using 3 approaches: 1) as a static variable (ever having a relative with breast cancer); 2) as accumulative history; and 3) as a dynamic variable (time-dependent variable).

RESULTS

For women aged <50 years, familial risk was mostly higher when family history was assessed as a dynamic variable compared with using a static or accumulative family history. For example, the cumulative risk of receiving a breast cancer diagnosis until age 50 years for women with a history of breast cancer in 1 first-degree relative was 2.6% (95% CI, 2.5%-2.7%) using the static method, 2.4% (95% CI, 2.3%-2.4%) using the accumulative method, and 3.1% (95% CI, 3.0%-3.2%) using the dynamic method. Relative risk in women aged <50 years with a breast cancer diagnosis in a sister was 1.40-fold (95% CI, 1.31-fold to 1.48-fold) using the static method, 1.66-fold (95% CI, 1.57-fold to 1.76-fold) using the accumulative method, and 2.28-fold (95% CI, 2.07-fold to 2.51-fold) using the dynamic method.

CONCLUSIONS

The results of the current study demonstrated that assessing family history as static, accumulative, or dynamic results in different familial risk estimates. The answer as to which method to use for family history assessment depends on the implications of the study, with the dynamic method appearing to be better suited for risk stratification studies, the accumulative method being the most convenient in practice and the least favored for risk prediction, and the static method being suitable for etiological impact and risk attribution studies.

Propensity score analysis for time-dependent exposure

Propensity score analysis (PSA) is widely used in medical literature to account for confounders. Conventionally, the propensity score (PS) is calculated by a binary logistic regression model using time-fixed covariates. In the presence of time-varying treatment or exposure, the conventional method may cause bias because subjects with early and late exposure are treated as the same. In effect, subjects who are treated latter can be different from those who are treated early. Thus, the conventional PSA must be modified to address this bias. In this paper, we illustrate how to perform analysis in the presence of time-dependent exposure. We conduct a simulation study with a known treatment effect. In the simulation study, we find the PSA method that directly adjust PS estimated by either a binary logistic regression model or a Cox regression model using time-fixed covariates still introduce significant bias. On the other hand, the time-dependent PS matching can help to achieve a result approaching the true effect. After time-dependent PS matching, the matched cohort can be analyzed with conventional Cox regression model or conditional logistic regression (CLR) model with time strata. The performance is comparable to the correctly specified Cox regression model with time-varying covariates (i.e., adjusting the exposure in a multivariable model as a time-varying covariate). We further develop a function called TDPSM() for time-dependent PS matching and it is applied to a real world dataset.

Molecular Dynamics of Lipopolysaccharide-Induced Lung Injury in Rodents

Acute respiratory distress syndrome (ARDS) is a common disease entity in critical care medicine and is still associated with a high mortality. Because of the heterogeneous character of ARDS, animal models are an insturment to study pathology in relatively standardized conditions. Rodent models can bridge the gap from in vitro investigations to large animal and clinical trials by facilitating large sample sizes under physiological conditions at comparatively low costs. One of the most commonly used rodent models of acute lung inflammation and ARDS is administration of lipopolysaccharide (LPS), either into the airways (direct, pulmonary insult) or systemically (indirect, extra-pulmonary insult). This narrative review discusses the dynamics of important pathophysiological pathways contributing to the physiological response to LPS-induced injury. Pathophysiological pathways of LPS-induced lung injury are not only influenced by the type of the primary insult (e.g., pulmonary or extra-pulmonary) and presence of additional stimuli (e.g., mechanical ventilation), but also by time. As such, findings in animal models of LPS-induced lung injury may depend on the time point at which samples are obtained and physiological data are captured. This review summarizes the current evidence and highlights uncertainties on the molecular dynamics of LPS-induced lung injury in rodent models, encouraging researchers to take accurate timing of LPS-induced injury into account when designing experimental trials.

Spontaneous evolution of human skin fibroblasts into wound-healing keratinocyte-like cells

Producing keratinocyte cells (KCs) in large scale is difficult due to their slow proliferation, disabling their use as seed cells for skin regeneration and wound healing. Cell reprogramming is a promising inducer-based approach to KC production but only reaches very low cellular conversion. Here we reported a unique cellular conversion phenomenon, where human skin fibroblasts (FBs) were spontaneously converted into keratinocyte-like cells (KLCs) over the time without using any inducers.

Methods: FBs were routinely cultured for more than 120 days in regular culture medium. Characteristics of KLCs were checked at the molecular and cellular level. Then the functionality and safety of the KLCs were verified by wound healing and tumorigenicity assay, respectively. To identify the mechanism of the cell conversion phenomenon, high-throughput RNA sequencing was also performed.

Results: The global conversion started on day 90 and reached 90% on day 110. The KLCs were as functional and effective as KCs in wound healing without causing oncogenicity. The conversion was regulated via a PI3K-AKT signaling pathway mediated by a long non-coding RNA, LINC00672. Modulating the pathway could shorten the conversion time to 14 days.

Conclusion: The discovered FBs-KLCs conversion in the study might open a new avenue to the scalable production of cell sources needed for regenerating skins and healing large-area wounds.

Cellular ATP levels are affected by moderate and strong static magnetic fields

Mitochondrion is the major cellular energy producing organelle that is at the boundary between chemical reactions and physical processes. Although mitochondria have been shown to be affected by physical methods such as nonthermal plasma, whether static magnetic field (SMF) could also affect them is still unclear. Here we used rat adrenal PC12 cells to compare SMFs of different intensities for their effects on ATP (adenosine-5'-triphosphate), the major energy source produced by mitochondria, which is essential for various cellular processes. Our results show that although 0.26 or 0.50 T SMFs did not affect ATP, 1 T and 9 T SMFs affected ATP level differently and time-dependently. Moreover, SMF-induced ATP level fluctuations are correlated with mitochondrial membrane potential changes. Our study provides insights not only into understanding various cellular effects of SMFs, but also the potential clinical applications of SMFs. Bioelectromagnetics. 39:352-360, 2018. © 2018 Wiley Periodicals, Inc.

High-fat Diet Mediates Anxiolytic-like Behaviors in a Time-dependent Manner Through the Regulation of SIRT1 in the Brain

The consumption of a high-fat diet (HFD) and obesity have been associated not only with metabolic diseases but also with neuropsychiatric diseases, such as depression and anxiety. However, results on the effects of an HFD on anxiety are controversial, since both anxiogenic and anxiolytic effects have been reported. In this study, we evaluated the effects of both short- and long-term intake of an HFD on anxiety-like behaviors. To explore the impact of time on the association between an HFD and anxiety, mice were fed with an HFD for 4 weeks or 12 weeks. Compared with control-diet mice, mice given an HFD for 4 weeks displayed anxiolytic-like behaviors. At the same time, we observed decreased SIRT1 expression in the mPFC and the amygdala of HFD-fed mice. Moreover, resveratrol, an activator of SIRT1, reversed the anxiolytic-like behaviors in HFD-fed mice. However, after 12 weeks of consuming a high-fat diet, mice did not exhibit any anti-anxiety behavior or further decreases in SIRT1 expression in the aforementioned brain regions compared with CD-fed mice. When EX-527, a SIRT1 inhibitor, was intraperitoneally injected, we observed anxiolytic effects in the CD-fed mice but not in the 12-week HFD-fed mice. Collectively, our data demonstrate that exposure to a short-term HFD can induce anxiolytic behaviors, which may be associated with decreased SIRT1 in the mPFC and the amygdala. However, this effect is abolished when the high-fat diet is extended to 12 weeks. Together, these results demonstrate that SIRT1 plays an essential role in regulating mood-related behaviors in HFD-fed mice.

Immortal Time Bias in Observational Studies of Time-to-Event Outcomes: Assessing Effects of Postmastectomy Radiation Therapy Using the National Cancer Database

The objectives of this study are to illustrate the effects of immortal time bias (ITB) using an oncology outcomes database and quantify through simulations the magnitude and direction of ITB when different analytical techniques are used. A cohort of 11 626 women who received neoadjuvant chemotherapy and underwent mastectomy with pathologically positive lymph nodes were accrued from the National Cancer Database (2004-2008). Standard Cox regression, time-dependent (TD), and landmark models were used to compare overall survival in patients who did or did not receive postmastectomy radiation therapy (PMRT). Simulation studies showing ways to reduce the effect of ITB indicate that TD exposures should be included as variables in hazard-based analyses. Standard Cox regression models comparing overall survival in patients who did and did not receive PMRT showed a significant treatment effect (hazard ratio [HR]: 0.93, 95% confidence interval [CI]: 0.88-0.99). Time-dependent and landmark methods estimated no treatment effect with HR: 0.97, 95% CI: 0.92 to 1.03 and HR: 0.98, 95% CI, 0.92 to 1.04, respectively. In our simulation studies, the standard Cox regression model significantly overestimated treatment effects when no effect was present. Estimates of TD models were closest to the true treatment effect. Landmark model results were highly dependent on landmark timing. Appropriate statistical approaches that account for ITB are critical to minimize bias when examining relationships between receipt of PMRT and survival.

Evaluation of Rosin Gum and Eudragit® RS PO as a Functional Film Coating Material

Polymers are essential tools in the research and development of new therapeutic devices. The diversity and flexibility of these materials have generated high expectations in the composition of new materials with extraordinary abilities, especially in the design of new systems for the modified release of pharmaceutically active ingredients. The natural polymer rosin features moisture protection and pH-dependent behavior (i.e., it is sensitive to pH > 7.0), suggesting its possible use in pharmaceutical systems. The synthetic polymer Eudragit® RS PO is a low-permeability material, the disintegration of which depends on the time of residence in the gastrointestinal tract. The present study developed a polymeric material with desirable physicochemical characteristics and synergistic effects that resulted from the inherent properties of the associated polymers. Isolated films were obtained by solvent evaporation and subjected to a water vapor transmission test, scanning electron microscopy, calorimetry, Fourier transform-infrared (FT-IR) spectroscopy, micro-Raman spectroscopy, and mechanical analysis. The new polymeric material was macroscopically continuous and homogeneous, was appropriately flexible, had low water permeability, was vulnerable in alkaline environments, and was thermally stable, maintaining an unchanged structure up to temperatures of ∼400°C. The new material also presented potentially suitable characteristics for application in film coatings for oral solids, suggesting that it is capable of carrying therapeutic substances to distal regions of the gastrointestinal tract. These findings indicate that this new material may be added to the list of functional excipients.

Time-dependent effect of electrical stimulation on osteogenic differentiation of bone mesenchymal stromal cells cultured on conductive nanofibers

Bone tissue engineering using bone mesenchymal stromal cells (BMSCs) is a multidisciplinary strategy that requires biodegradable scaffold, cell, various promoting cues to work simultaneously. Electrical stimulation (ES) is known able to promote osteogenic differentiation of BMSCs, but it is interesting to know how can it play the strongest promotion effect. To strengthen local ES on BMSCs, parallel-aligned conductive nanofibers were electrospun from the mixtures of poly(L-lactide) (PLLA) and multi-walled carbon nanotubes (MWCNTs), and used for cell culture. Osteogenic differentiation of BMSCs was conducted by applying ES (direct current, 1.5 V, 1.5 h/day) perpendicular to the fiber direction during the day 1-7, day 8-14, or day 15-21 period of the osteoinductive culture. In comparison with ES-free groups, bone-related markers and genes were found significantly up-regulated when ES was applied on BMSCs growing on nanofibers having higher conductivity. When the ES was applied at the earlier stage of osteoinductive culture, the promotion effect on osteogenic differentiation would be stronger. In the presence of a BMP blocker, the down-regulated expressions of bone-related genes were able to be slightly recovered by ES, especially when the ES was applied at the beginning of osteoinductive culture (i.e. day 1-7). The promotion effect generated by ES in the early stage was found sustainable to later stages of differentiation, while those ES applied at later stages of differentiation should have missed the optimal point. In other words, later ES was not so necessary in inducing the osteogenic differentiation of BMSCs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3369-3383, 2017.

Time-Dependent Effects of Acute Exercise on University Students' Cognitive Performance in Temperate and Cold Environments

Background: Few studies have examined the acute exercise-induced changes in cognitive performance in different thermal environments and the time course effects.

Objective: Investigate the time-dependent effects of acute exercise on university students’ processing speed, working memory and cognitive flexibility in temperate and cold environments.

Method: Twenty male university students (age 23.5 ± 2.0 years) with moderate physical activity level participated in a repeated-measures within-subjects design. Processing speed, working memory and cognitive flexibility were assessed using CogState test battery at baseline (BASE), followed by a 45-min rest (REST), immediately after (EX) and 30 min after (POST-EX) 30-min moderate-intensity treadmill running in both temperate (TEMP; 25°C) and cold (COLD; 10°C) environments. Mean skin temperature (MST) and thermal sensation (TS) were also recorded. Two-way repeated measures ANOVA was performed to analyze each variable. Spearman’s rho was used to identify the correlations between MST, TS and cognitive performance.

Results: Reaction time (RT) of processing speed and working memory decreased immediately after exercise in both conditions (processing speed: p = 0.003; working memory: p = 0.007). The facilitating effects on processing speed disappeared within 30 min after exercise in TEMP (p = 0.163) and COLD (p = 0.667), while improvements on working memory remained 30 min after exercise in TEMP (p = 0.047), but not in COLD (p = 0.663). Though RT of cognitive flexibility reduced in both conditions (p = 0.003), no significance was found between EX and REST (p = 0.135). Increased MST and TS were significantly associated with reductions in processing speed RT (MST: r = -0.341, p < 0.001; TS: r = -0.262, p = 0.001) and working memory RT (MST: r = -0.282, p < 0.001; TS: r = -0.2229, p = 0.005), and improvements in working memory accuracy (MST: r = 0.249, p = 0.002; TS: r = 0.255, p = 0.001).

Conclusion: The results demonstrate different time-dependent effects of acute exercise on cognition in TEMP and COLD. Our study reveals facilitating effects of exercise on university students’ processing speed and working memory in both environments. However, in contrast to TEMP, effects on working memory in COLD are transient.

Ecological Succession Pattern of Fungal Community in Soil along a Retreating Glacier

Accelerated by global climate changing, retreating glaciers leave behind soil chronosequences of primary succession. Current knowledge of primary succession is mainly from studies of vegetation dynamics, whereas information about belowground microbes remains unclear. Here, we combined shifts in community assembly processes with microbial primary succession to better understand mechanisms governing the stochastic/deterministic balance. We investigated fungal succession and community assembly via high-throughput sequencing along a well-established glacier forefront chronosequence that spans 2-188 years of deglaciation. Shannon diversity and evenness peaked at a distance of 370 m and declined afterwards. The response of fungal diversity to distance varied in different phyla. Basidiomycota Shannon diversity significantly decreased with distance, while the pattern of Rozellomycota Shannon diversity was unimodal. Abundance of most frequencies OTU2 (Cryptococcus terricola) increased with successional distance, whereas that of OTU65 (Tolypocladium tundrense) decreased. Based on null deviation analyses, composition of the fungal community was initially governed by deterministic processes strongly but later less deterministic processes. Our results revealed that distance, altitude, soil microbial biomass carbon, soil microbial biomass nitrogen and [Formula: see text]-N significantly correlated with fungal community composition along the chronosequence. These results suggest that the drivers of fungal community are dynamics in a glacier chronosequence, that may relate to fungal ecophysiological traits and adaptation in an evolving ecosystem. The information will provide understanding the mechanistic underpinnings of microbial community assembly during ecosystem succession under different scales and scenario.

The joint contribution of diabetes and work disability to premature death during working age: a population-based study in Sweden

AIMS

We aimed to examine how newly diagnosed diabetes and work disability jointly predict death during working age.

METHODS

We used prospective population-based register data of 25-59-year-old adults who had lived in Sweden since 2002. All those with onset of diabetes recorded in 2006 were included (n=14266). A 2% random sample (n=78598) was drawn from the general population, comprising people with no indication of diabetes during 2003-2010. Net days of sickness absence and disability pension in 2005-2006 were examined; the follow-up time for mortality was 2007-2010. Cox regression models were fitted (hazard ratios, HR, 95% confidence interval, CI) adjusting for sociodemographics and time-dependent health conditions.

RESULTS

Individuals with diabetes and work disability for over 6 months were at a higher risk of premature death (HR=14.2, 95% CI 12.0-16.8) than their counterparts without diabetes and work disability. A high risk was also observed among people without diabetes but equally prolonged work disability (HR=6.4, 95% CI 5.4-7.6). Diabetes was associated with premature death even without work disability (HR=3.5, 95% CI 2.8-4.4). The associations were particularly attenuated after adjustment for health conditions assessed over the follow-up.

CONCLUSIONS

DIABETES AND WORK DISABILITY JOINTLY INCREASE THE RISK OF DEATH DURING WORKING AGE DIABETES WITH LONG-TERM WORK DISABILITY IS ASSOCIATED WITH THE HIGHEST RISK OF PREMATURE DEATH, WHICH HIGHLIGHTS THE IMPORTANCE OF THEIR PREVENTION AND EARLY DETECTION.

Time-Dependent Metabolism of Luteolin by Human UDP-Glucuronosyltransferases and Its Intestinal First-Pass Glucuronidation in Mice

Luteolin is a well-known flavonoid with various pharmacological properties but has low bioavailability due to glucuronidation. This study investigated the time-course of luteolin glucuronidation by 12 human UDP-glucuronosyltransferases (UGTs) and its intestinal first-pass metabolism in mice. Six metabolites, including two novel abundant diglucuronides [3',7-O-diglucuronide (diG) and 4',7-diG] and four known ones, were identified. UGT1A6 and UGT1A9 generated almost only monoglucuronides (G's). The production of 3',7-diG followed a sequential time-dependent process along with decrease of 3'-G mainly by UGT1A1, indicating that 3',7-diG was produced from 3'-G. Metabolism in mice intestine differed from that in humans. Probenecid, a nonspecific UGT inhibitor, did not affect absorption but significantly inhibited production of 7-, 4'-, and 3'-G, and enhanced the formation of another novel metabolite, 5-G, in mice. In conclusion, diglucuronide formation is time-dependent and isoform-specific. UGT1A1 preferentially generates diG, whereas UGT1A6 and UGT1A9 share a preference for G production.

Joint modeling of survival and longitudinal non-survival data: current methods and issues. Report of the DIA Bayesian joint modeling working group

Explicitly modeling underlying relationships between a survival endpoint and processes that generate longitudinal measured or reported outcomes potentially could improve the efficiency of clinical trials and provide greater insight into the various dimensions of the clinical effect of interventions included in the trials. Various strategies have been proposed for using longitudinal findings to elucidate intervention effects on clinical outcomes such as survival. The application of specifically Bayesian approaches for constructing models that address longitudinal and survival outcomes explicitly has been recently addressed in the literature. We review currently available methods for carrying out joint analyses, including issues of implementation and interpretation, identify software tools that can be used to carry out the necessary calculations, and review applications of the methodology.

Go with the flow-biology and genetics of the lactation cycle

Lactation is a dynamic process, which evolved to meet dietary demands of growing offspring. At the same time, the mother's metabolism changes to meet the high requirements of nutrient supply to the offspring. Through strong artificial selection, the strain of milk production on dairy cows is often associated with impaired health and fertility. This led to the incorporation of functional traits into breeding aims to counteract this negative association. Potentially, distributing the total quantity of milk per lactation cycle more equally over time could reduce the peak of physiological strain and improve health and fertility. During lactation many factors affect the production of milk: food intake; digestion, absorption, and transportation of nutrients; blood glucose levels; activity of cells in the mammary gland, liver, and adipose tissue; synthesis of proteins and fat in the secretory cells; and the metabolic and regulatory pathways that provide fatty acids, amino acids, and carbohydrates. Whilst the endocrine regulation and physiology of the dynamic process of milk production seems to be understood, the genetics that underlie these dynamics are still to be uncovered. Modeling of longitudinal traits and estimating the change in additive genetic variation over time has shown that the genetic contribution to the expression of a trait depends on the considered time-point. Such time-dependent studies could contribute to the discovery of missing heritability. Only very few studies have estimated exact gene and marker effects at different time-points during lactation. The most prominent gene affecting milk yield and milk fat, DGAT1, exhibits its main effects after peak production, whilst the casein genes have larger effects in early lactation. Understanding the physiological dynamics and elucidating the time-dependent genetic effects behind dynamically expressed traits will contribute to selection decisions to further improve productive and healthy breeding populations.

Cytochrome P450 time-dependent inhibition and induction: advances in assays, risk analysis and modelling

INTRODUCTION

It is widely accepted that current practice of polypharmacy inevitably increases the incidence of drug-drug interactions (DDIs). Serious DDIs are a major liability for new molecular entities entering the pharmaceutical market. Various strategies are employed to avoid problematic compounds for clinical development. Progress made with reversible CYP DDIs has prompted a switch to study and model time-dependent inhibition and induction interactions.

AREAS COVERED

An overview of popular experimental practices is presented with discussion of techniques and algorithms used to analyse the clinical DDI risk. Emphasis is placed on the transition from early, simple static equations, via more complex net mechanistic, static models to dynamic approaches involving multiple perpetrators and metabolites, simultaneous inhibition and induction.

EXPERT OPINION

Inclusion of the more conservative terms for parameters required for DDI evaluation may eliminate promising chemical space, encourages poor practice and hampers innovation. Breakthroughs have originated from understanding of 'outliers' from such analyses where CYP enzyme-transporter interplay may be involved. The role of key transporters in drug disposition is firmly established as the chemistry required to address new targets deviates from traditional 'drug-like' space. Attempts to model more complex interactions for substrates of both CYP enzymes and drug transporters are still in their infancy and will benefit from dynamic modelling.

Application of singular value decomposition analysis to time-dependent powder diffraction data of an in-situ photodimerization reaction

Singular value decomposition (SVD) analysis has important applications for time-dependent crystallographic data, extracting significant information. Herein, a successful application of SVD analysis of time-resolved powder diffraction data over the course of an in-situ photodimerization reaction of anthracene derivatives is introduced. SVD revealed significant results in the case of 9-methylanthracene and 1-chloroanthracene. The results support the formation of the 9-methylanthracene stable dimer phase and suggest the existence of an excimer state.

Hydrogels with time-dependent material properties enhance cardiomyocyte differentiation in vitro

Tissue-specific elastic modulus (E), or 'stiffness,' arises from developmental changes in the extracellular matrix (ECM) and suggests that progenitor cell differentiation may be optimal when physical conditions mimic tissue progression. For cardiomyocytes, maturing from mesoderm to adult myocardium results in a 9-fold stiffening originating in part from a change in collagen expression and localization. To mimic this temporal stiffness change in vitro, thiolated-hyaluronic acid (HA) hydrogels were crosslinked with poly(ethylene glycol) diacrylate, and their dynamics were modulated by changing crosslinker molecular weight. With the hydrogel appropriately tuned to stiffen as heart muscle does during development, pre-cardiac cells grown on collagen-coated HA hydrogels exhibit a 3-fold increase in mature cardiac specific markers and form up to 60% more maturing muscle fibers than they do when grown on compliant but static polyacrylamide hydrogels over 2 weeks. Though ester hydrolysis does not substantially alter hydrogel stiffening over 2 weeks in vitro, model predictions indicate that ester hydrolysis will eventually degrade the material with additional time, implying that this hydrogel may be appropriate for in vivo applications where temporally changing material properties enhance cell maturation prior to its replacement with host tissue.

In-vivo time-dependent articular cartilage contact behavior of the tibiofemoral joint

OBJECTIVE

The purpose of this study was to investigate the in-vivo time-dependent contact behavior of tibiofemoral cartilage of human subjects during the first 300 s after applying a constant full body weight loading and determine whether there are differences in cartilage contact responses between the medial and lateral compartments.

DESIGN

Six healthy knees were investigated in this study. Each knee joint was subjected to full body weight loading and the in-vivo positions of the knee were captured by two orthogonal fluoroscopes during the first 300 s after applying the load. Three-dimensional models of the knee were created from MR images and used to reproduce the in-vivo knee positions recorded by the fluoroscopes. The time-dependent contact behavior of the cartilage was represented using the peak cartilage contact deformation and the cartilage contact area as functions of time under the constant full body weight.

RESULTS

Both medial and lateral compartments showed a rapid increase in contact deformation and contact area during the first 20s of loading. After 50s of loading, the peak contact deformation values were 10.5+/-0.8% (medial) and 12.6+/-3.4% (lateral), and the contact areas were 223.9+/-14.8 mm(2) (medial) and 123.0+/-22.8 mm(2) (lateral). Thereafter, the peak cartilage contact deformation and contact area remained relatively constant. The respective changing rates of cartilage contact deformation were 1.4+/-0.9%/s (medial) and 3.1+/-2.5%/s (lateral); and of contact areas were 40.6+/-20.8 mm(2)/s (medial) and 24.0+/-11.4 mm(2)/s (lateral), at the first second of loading. Beyond 50 s, both changing rates approached zero.

CONCLUSIONS

The peak cartilage contact deformation increased rapidly within the first 20s of loading and remained relatively constant after approximately 50 s of loading. The time-dependent response of cartilage contact behavior under constant full body weight loading was significantly different in the medial and lateral tibiofemoral compartments, with greater peak cartilage contact deformation on the lateral side and greater contact area on the medial side. These data can provide insight into normal in-vivo cartilage function and provide guidelines for the improvement of ex-vivo cartilage experiments and the validation of computational models that simulate human knee joint contact.

Outcome after extended follow-up in a prospective study of operable breast cancer: key factors and a prognostic index

In 1990, 215 patients with operable breast cancer were entered into a prospective study of the prognostic significance of five biochemical markers and 15 other factors (pathological/chronological/patient). After a median follow-up of 6.6 years, there were 77 recurrences and 77 deaths (59 breast cancer-related). By univariate analysis, patient outcome related significantly to 13 factors. By multivariate analysis, the most important of nine independent factors were: number of nodes involved, steroid receptors (for oestrogen or progestogen), age, clinical or pathological tumour size and grade. Receptors and grade exerted their influence only in the first 3 years. Progestogen receptors (immunohistochemical) and oestrogen receptors (biochemical) were of similar prognostic significance. The two receptors were correlated (r=+0.50, P=0.001) and displaced each other from the analytical model but some evidence for the additivity of their prognostic values was seen when their levels were discordant.