The effects of aging on hepatic microsomal scaling factor and hepatocellularity number in the horse

Scaling factor values for the in vitro-in vivo extrapolation of hepatic metabolic clearance for xenobiotics have not yet been determined in horses. Scaling factors were determined by comparing the total protein and or CYP P450 content in microsomes and cryopreserved hepatocytes against the content in the liver. Microsomal protein per gram of liver (MPPGL) and hepatocellularity number per gram of liver (HPGL) using CYP P450 content method ranged 41 - 73 mg/gram of liver (mean= 57 mg/gram of liver, n=39) and 146 - 320 × 106 cells/g of liver (mean = 227× 106 cells/g of liver, n=18), respectively; and 156 - 352 × 106 cells/g of liver (mean = 232× 106 cells/g of liver) using total protein method. A non-monotonic and inverse relationship between age and MPPGL and HPGL, respectively, was observed. Between 1 and 20 years of age the liver cell size decreases as age increases. Subsequently, the cell size increases until the hepatocytes of the oldest horses approached the size found in the youngest horses. Hepatocyte density was inversely related to the size of the hepatocytes. This study provides the first extensive and comprehensive data demonstrating the relationship between the size of hepatocytes and HPGL in any species

Plasma and urine pharmacokinetics of intravenously administered flunixin in greyhound dogs

© 2019 John Wiley & Sons Ltd Medication control in greyhound racing requires information from administration studies that measure drug levels in the urine as well as plasma, with time points that extend into the terminal phase of excretion. To characterize the plasma and the urinary pharmacokinetics of flunixin and enable regulatory advice for greyhound racing in respect of both medication and residue control limits, flunixin meglumine was administered intravenously on one occasion to six different greyhounds at the label dose of 1mg/kg and the levels of flunixin were measured in plasma for up to 96hr and in urine for up to 120hr. Using the standard methodology for medication control, the irrelevant plasma concentration was determined as 1ng/ml and the irrelevant urine concentration was determined as 30ng/ml. This information can be used by regulators to determine a screening limit, detection time and a residue limit. The greyhounds with the highest average urine pH had far greater flunixin exposure compared with the greyhounds that had the lowest. This is entirely consistent with the extent of ionization predicted by the Henderson–Hasselbalch equation. This variability in the urine pharmacokinetics reduces with time, and at 72hr postadministration, in the terminal phase, the variability in urine and plasma flunixin concentrations are similar and should not affect medication control

Hydrostatic pressure regulates CYP1A2 expression in human hepatocytes via a mechanosensitive aryl hydrocarbon receptor-dependent pathway

Approximately 75% of xenobiotics are primarily eliminated through metabolism; thus the accurate scaling of metabolic clearance is vital to successful drug development. Yet, when data is scaled from in vitro to in vivo, hepatic metabolic clearance, the primary source of metabolism, is still commonly underpredicted. Over the past decades, with biophysics used as a key component to restore aspects of the in vivo environment, several new cell culture settings have been investigated to improve hepatocyte functionalities. Most of these studies have focused on shear stress, i.e., flow mediated by a pressure gradient. One potential conclusion of these studies is that hepatocytes are naturally "mechanosensitive," i.e., they respond to a change in their biophysical environment. We demonstrate that hepatocytes also respond to an increase in hydrostatic pressure that, we suggest, is directly linked to the lobule geometry and vessel density. Furthermore, we demonstrate that hydrostatic pressure improves albumin production and increases cytochrome P-450 (CYP) 1A2 expression levels in an aryl hydrocarbon-dependent manner in human hepatocytes. Increased albumin production and CYP function are commonly attributed to the impacts of shear stress in microfluidic experiments. Therefore, our results highlight evidence of a novel link between hydrostatic pressure and CYP metabolism and demonstrate that the spectrum of hepatocyte mechanosensitivity might be larger than previously thought

The intravenous pharmacokinetics of butorphanol and detomidine dosed in combination compared with individual dose administrations to exercised horses

In equine and racing practice, detomidine and butorphanol are commonly used in combination for their sedative properties. The aim of the study was to produce detection times to better inform European veterinary surgeons, so that both drugs can be used appropriately under regulatory rules. Three independent groups of 7, 8 and 6 horses, respectively, were given either a single intravenous administration of butorphanol (100 mu g/kg), a single intravenous administration of detomidine (10 mu g/kg) or a combination of both at 25 (butorphanol) and 10 (detomidine) mu g/kg. Plasma and urine concentrations of butorphanol, detomidine and 3-hydroxydetomidine at predetermined time points were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The intravenous pharmacokinetics of butorphanol dosed individually compared with co-administration with detomidine had approximately a twofold larger clearance (646 +/- 137 vs. 380 +/- 86 ml hr(-1) kg(-1)) but similar terminal half-life (5.21 +/- 1.56 vs. 5.43 +/- 0.44 hr). Pseudo-steady-state urine to plasma butorphanol concentration ratios were 730 and 560, respectively. The intravenous pharmacokinetics of detomidine dosed as a single administration compared with co-administration with butorphanol had similar clearance (3,278 +/- 1,412 vs. 2,519 +/- 630 ml hr(-1) kg(-1)) but a slightly shorter terminal half-life (0.57 +/- 0.06 vs. 0.70 +/- 0.11 hr). Pseudo-steady-state urine to plasma detomidine concentration ratios are 4 and 8, respectively. The 3-hydroxy metabolite of detomidine was detected for at least 35 hr in urine from both the single and co-administrations. Detection times of 72 and 48 hr are recommended for the control of butorphanol and detomidine, respectively, in horseracing and equestrian competitions

PATH-10. Accelerating comprehensive CNS tumor molecular diagnostics with Rapid-CNS2 and MNP-flex: a prospective multi-center validation [Abstract]

BACKGROUND The 2021 WHO classification update highlights the necessity of integrating molecular alterations for precise central nervous system (CNS) tumor diagnoses. However, current molecular reporting methods are hindered by significant initial investment, labor-intensive protocols, and lengthy turnaround times. Methylation-based classification has emerged as a pivotal diagnostic tool but is currently limited to array-based techniques. This necessitates exploration of novel technologies to streamline molecular analysis. METHODS We implemented Rapid-CNS2 - our adaptive sampling-based nanopore sequencing workflow- on 190 adult and pediatric samples at University Hospital Heidelberg and University of Nottingham. Intraoperative potential was assessed through real-time analysis followed by 24-hour sequencing for comprehensive genomic insights. Additionally, we developed MNP-Flex, a platform-agnostic version of the Heidelberg methylation classifier covering 184 CNS tumor classes. We evaluated MNP-flex on a global cohort of over 78,000 samples from methylation arrays, whole genome bisulfite sequencing, nanopore whole genome sequencing, methylation panels and Rapid-CNS2. RESULTS Rapid-CNS2 validation yielded accurate integrated diagnoses in all 190 samples. Within a crucial 30-minute timeframe, we reported accurate methylation families and arm-level copy number profiles followed by next-day reporting of fine-grained methylation classification, SNVs, focal CNVs, MGMT status, fusions and novel structural variants. Moreover, MNP-Flex achieved 92% accuracy over the validation dataset spanning over 78,000 samples from five different technologies. CONCLUSIONS The adoption of Rapid-CNS2 and MNP-Flex enables rapid intraoperative broad methylation classification and copy number alteration reporting within 30 minutes, with additional clinically relevant, fine-grained molecular insights available the following day. It offers clinicians rapid access to comprehensive molecular information critical for treatment decisions. Furthermore, MNP-Flex extends the utility of the Heidelberg methylation classifier to diverse sequencing-based data. By overcoming the limitations of currently available methods, our workflow represents a paradigm shift in the field, promising improved management of CNS tumor patients. Rapid-CNS2 can be executed with a single command, while MNP-Flex is publicly available as a web service, enhancing accessibility and usability for clinical applications

A quantitative systems pharmacology approach, incorporating a novel liver model, for predicting pharmacokinetic drug-drug interactions

All pharmaceutical companies are required to assess pharmacokinetic drug-drug interactions (DDIs) of new chemical entities (NCEs) and mathematical prediction helps to select the best NCE candidate with regard to adverse effects resulting from a DDI before any costly clinical studies. Most current models assume that the liver is a homogeneous organ where the majority of the metabolism occurs. However, the circulatory system of the liver has a complex hierarchical geometry which distributes xenobiotics throughout the organ. Nevertheless, the lobule (liver unit), located at the end of each branch, is composed of many sinusoids where the blood flow can vary and therefore creates heterogeneity (e.g. drug concentration, enzyme level). A liver model was constructed by describing the geometry of a lobule, where the blood velocity increases toward the central vein, and by modeling the exchange mechanisms between the blood and hepatocytes. Moreover, the three major DDI mechanisms of metabolic enzymes; competitive inhibition, mechanism based inhibition and induction, were accounted for with an undefined number of drugs and/or enzymes. The liver model was incorporated into a physiological-based pharmacokinetic (PBPK) model and simulations produced, that in turn were compared to ten clinical results. The liver model generated a hierarchy of 5 sinusoidal levels and estimated a blood volume of 283 mL and a cell density of 193 × 106 cells/g in the liver. The overall PBPK model predicted the pharmacokinetics of midazolam and the magnitude of the clinical DDI with perpetrator drug(s) including spatial and temporal enzyme levels changes. The model presented herein may reduce costs and the use of laboratory animals and give the opportunity to explore different clinical scenarios, which reduce the risk of adverse events, prior to costly human clinical studies

A history of high-power laser research and development in the United Kingdom

The first demonstration of laser action in ruby was made in 1960 by T. H. Maiman of Hughes Research Laboratories, USA. Many laboratories worldwide began the search for lasers using different materials, operating at different wavelengths. In the UK, academia, industry and the central laboratories took up the challenge from the earliest days to develop these systems for a broad range of applications. This historical review looks at the contribution the UK has made to the advancement of the technology, the development of systems and components and their exploitation over the last 60 years