Assessing drug exposure in rodent toxicity studies without satellite animals

Five major objectives for pharmacokinetic investigations in support of toxicity studies are identified as follows: Assess whether animals exhibited measurable blood concentrations in a dose-dependent manner; estimate average area under the concentration- time curve (AUC)and maximal concentration (C _max )for each treatment group; elucidate general patterns in the concentration-time (CxT)profile, and summarize relationships between CxTand treatment group; determine CxTdependence on day into study; and judge interanimal variability and identify any animals with unusual concentration response. Such objectives are generally addressed in rodent toxicity studies by including satellite animals in the study. Satellite animals are extra animals dosed as per protocol but not subjected to toxicological and pathological observations and tests. Instead, they are used exclusively for the evaluation of pharmacokinetic characteristics of the test compound. In this paper, methods are described for achieving the five listed pharmacokinetic objectives in rodent toxicity studies without the use of satellite animals. A rat toxicity study is presented as an example.     

Experimental Testing of the Action of Vitamin D and Silicon Chelates in Bone Fracture Healing and Bone Turnover in Mice and Rats

This study presents findings on the biological action of an integrated supplement containing the following components involved in osteogenesis and mineralization: vitamin D and silicon in the bioavailable and soluble form. A hypothesis that these components potentiate one another’s action and make calcium absorption by the body more efficient was tested. Biological tests of the effect of vitamin D and silicon chelates on bone fracture healing and bone turnover were conducted using ICR mice and albino Wistar rats. Radiographic and biochemical studies show that the supplement simultaneously containing silicon chelates and vitamin D stimulates bone tissue regeneration upon mechanical defects and accelerates differentiation of osteogenic cells, regeneration of spongy and compact bones, and restoration of bone structure due to activation of osteoblast performance. Bone structure restoration was accompanied by less damage to skeletal bones, apparently due to better absorption of calcium from food. The studied supplement has a similar effect when used to manage physiologically induced decalcification, thus holding potential for the treatment of osteomalacia during pregnancy or occupational diseases (e.g., for managing bone decalcification in astronauts).     

Abnormalities of the executive control network in multiple sclerosis phenotypes: An fMRI effective connectivity study

The Stroop interference task is a cognitively demanding task of executive control, a cognitive ability that is often impaired in patients with multiple sclerosis (MS). The aim of this study was to compare effective connectivity patterns within a network of brain regions involved in the Stroop task performance between MS patients with three disease clinical phenotypes [relapsing‐remitting (RRMS), benign (BMS), and secondary progressive (SPMS)] and healthy subjects. Effective connectivity analysis was performed on Stroop task data using a novel method based on causal Bayes networks. Compared with controls, MS phenotypes were slower at performing the task and had reduced performance accuracy during incongruent trials that required increased cognitive control. MS phenotypes also exhibited connectivity abnormalities reflected as weaker shared connections, presence of extra connections (i.e., connections absent in the HC connectivity pattern), connection reversal, and loss. In SPMS and the BMS groups but not in the RRMS group, extra connections were associated with deficits in the Stroop task performance. In the BMS group, the response time associated with correct responses during the congruent condition showed a positive correlation with the left posterior parietal → dorsal anterior cingulate connection. In the SPMS group, performance accuracy during the congruent condition showed a negative correlation with the right insula → left insula connection. No associations between extra connections and behavioral performance measures were observed in the RRMS group. These results suggest that, depending on the phenotype, patients with MS use different strategies when cognitive control demands are high and rely on different network connections. Hum Brain Mapp, 37:2293–2304, 2016. © 2016 Wiley Periodicals, Inc.     

Role of pelvic drain and timing of urethral catheter removal following RARP: a systematic review and meta-analysis

Objectives

To assess the clinical value of routine pelvic drain (PD) placement and early removal of urethral catheter (UC) in patients undergoing robot-assisted radical prostatectomy (RARP), as perioperative management such as the necessity of PD or optimal timing for UC removal remains highly variable.

Methods

Multiple databases were searched for articles published before March 2022 according to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statement. Studies were deemed eligible if they investigated the differential rate of postoperative complications between patients with/without routine PD placement and with/without early UC removal, defined as UC removal at 2–4 days after RARP.

Results

Overall, eight studies comprising 5112 patients were eligible for the analysis of PD placement, and six studies comprising 2598 patients were eligible for the analysis of UC removal. There were no differences in the rate of any complications (pooled odds ratio [OR] 0.89, 95% confidence interval [CI] 0.78–1.00), severe complications (Clavien–Dindo Grade ≥III; pooled OR 0.95, 95% CI 0.54–1.69), all and/or symptomatic lymphocele (pooled OR 0.82, 95% CI 0.50–1.33; and pooled OR 0.58, 95% CI 0.26–1.29, respectively) between patients with or without routine PD placement. Furthermore, avoiding PD placement decreased the rate of postoperative ileus (pooled OR 0.70, 95% CI 0.51–0.91). Early removal of UC resulted in an increased likelihood of urinary retention (OR 6.21, 95% CI 3.54–10.9) in retrospective, but not in prospective studies. There were no differences in anastomosis leakage and early continence rates between patients with or those without early removal of UC.

Conclusions

There is no benefit for routine PD placement after standard RARP in the published articles. Early removal of UC seems possible with the caveat of the increased risk of urinary retention, while the effect on medium-term continence is still unclear. These data may help guide the standardisation of postoperative procedures by avoiding unnecessary interventions, thereby reducing potential complications and associated costs.