Dynamics of cerebral blood volume during and after middle cerebral artery occlusion in rats - Comparison between ultrafast ultrasound and dynamic susceptibility contrast-enhanced MRI measurements.

Tomographic perfusion imaging techniques are integral to translational stroke research paradigms that advance our understanding of the disease. Functional ultrasound (fUS) is an emerging technique that informs on cerebral blood volume (CBV) through ultrasensitive Doppler and flow velocity (CBFv) through ultrafast localization microscopy. It is not known how experimental results compare with a classical CBV-probing technique such as dynamic susceptibility contrast-enhanced perfusion MRI (DSC-MRI). To that end, we assessed hemodynamics based on uUS (n = 6) or DSC-MRI (n = 7) before, during and up to three hours after 90-minute filament-induced middle cerebral artery occlusion (MCAO) in rats. Recanalization was followed by a brief hyperperfusion response, after which CBV and CBFv temporarily normalized but progressively declined after one hour in the lesion territory. DSC-MRI data corroborated the incomplete restoration of CBV after recanalization, which may have been caused by the free-breathing anesthetic regimen. During occlusion, MCAO-induced hypoperfusion was more discrepant between either technique, likely attributable to artefactual signal mechanisms related to slow flow, and processing algorithms employed for either technique. In vivo uUS- and DSC-MRI-derived measures of CBV enable serial whole-brain assessment of post-stroke hemodynamics, but readouts from both techniques need to be interpreted cautiously in situations of very low blood flow.

Radiosensitisation by olaparib through focused ultrasound delivery in a diffuse midline glioma model.

BACKGROUND AND PURPOSE: Diffuse midline glioma H3K27-altered (DMG) is an aggressive, inoperable, predominantly paediatric brain tumour. Treatment strategies are limited, resulting in a median survival of only 11 months. Currently, radiotherapy (RT), often combined with temozolomide, is considered the standard of care but remains palliative, highlighting the urgency for new therapies. Radiosensitisation by olaparib, an inhibitor of PARP1 and subsequently PAR-synthesis, is a promising treatment option. We assessed whether PARP1 inhibition enhances radiosensitivity in vitro and in vivo following focused ultrasound mediated blood-brain barrier opening (FUS-BBBO). METHODS: Effects of PARP1 inhibition were evaluated in vitro using viability, clonogenic, and neurosphere assays. In vivo olaparib extravasation and pharmacokinetic profiling following FUS-BBBO was measured by LC-MS/MS. Survival benefit of FUS-BBBO combined with olaparib and RT was assessed using a patient-derived xenograft (PDX) DMG mouse model. RESULTS: Treatment with olaparib in combination with radiation delayed tumour cell proliferation in vitro through the reduction of PAR. Prolonged exposure of low olaparib concentration was more efficient in delaying cell growth than short exposure of high concentration. FUS-BBBO increased olaparib bioavailability in the pons by 5.36-fold without observable adverse effects. A Cmax of 54.09 µM in blood and 1.39 µM in the pontine region was achieved following administration of 100 mg/kg olaparib. Although RT combined with FUS-BBBO mediated olaparib extravasation delayed local tumour growth, survival benefits were not observed in an in vivo DMG PDX model. CONCLUSIONS: Olaparib effectively radiosensitises DMG cells in vitro and reduces primary tumour growth in vivo when combined with RT. Further studies are needed to investigate the therapeutic benefit of olaparib in suitable preclinical PDX models.

Towards Standardisation of a Diffuse Midline Glioma Patient-Derived Xenograft Mouse Model Based on Suspension Matrices for Preclinical Research.

Diffuse midline glioma (DMG) is an aggressive brain tumour with high mortality and limited clinical therapeutic options. Although in vitro research has shown the effectiveness of medication, successful translation to the clinic remains elusive. A literature search highlighted the high variability and lack of standardisation in protocols applied for establishing the commonly used HSJD-DIPG-007 patient-derived xenograft (PDX) model, based on animal host, injection location, number of cells inoculated, volume, and suspension matrices. This study evaluated the HSJD-DIPG-007 PDX model with respect to its ability to mimic human disease progression for therapeutic testing in vivo. The mice received intracranial injections of HSJD-DIPG-007 cells suspended in either PBS or Matrigel. Survival, tumour growth, and metastases were assessed to evaluate differences in the suspension matrix used. After cell implantation, no severe side effects were observed. Additionally, no differences were detected in terms of survival or tumour growth between the two suspension groups. We observed delayed metastases in the Matrigel group, with a significant difference compared to mice with PBS-suspended cells. In conclusion, using Matrigel as a suspension matrix is a reliable method for establishing a DMG PDX mouse model, with delayed metastases formation and is a step forward to obtaining a standardised in vivo PDX model.

Radical cystectomy for clinically muscle invasive bladder cancer: does prior non-invasive disease affect clinical outcomes?

PURPOSE: To compare clinical and pathologic outcomes of radical cystectomy for muscle invasive bladder cancer in relation to prior history of non-invasive urothelial carcinoma. MATERIALS AND METHODS: Retrospective data collected from 1,150 patients managed by radical cystectomy for urothelial carcinoma of the bladder from the Canadian Bladder Cancer Network were analysed. Patients with clinical stage T2 or more were included and divided into two groups: (Group 1) patients with prior history of non-invasive urothelial carcinoma (N = 365) and (Group 2) patients with clinical muscle invasive cancer de novo (N = 785). Variables analysed included patient age, gender, pathologic stage, adjuvant chemotherapy, recurrence and mortality. RESULTS: Both groups were nearly equal in mean age and gender distribution, with mean ages of 67.2 and 66.7 years, and 79.7 and 79.5%, respectively (P = 0.4 and 0.9, respectively). The presence of preoperative hydronephrosis was 20.8 and 32.6% (P = 0.0007) for groups 1 and 2, respectively. The rate of higher pathological stage (T3 or T4) was 36.3 and 58% (P < 0.0001), positive lymph nodes were 20.1 and 28.8% (P = 0.002), and lymphovascular invasion was 31.7 and 46.2% (P = 0.0001) for groups 1 and 2, respectively. The rate of adjuvant chemotherapy was 15.5 and 23.3% (P = 0.002) for groups 1 and 2, respectively. None of the sampled patients received neoadjuvant chemotherapy. The overall survival (OS) and disease-specific survival (DSS) rates at 5 years were 62 and 70% for group 1 and 51 and 60% for group 2, respectively, while at 10 years, OS and DSS were 46 and 66% for group 1 and 35 and 49% for group 2, respectively (P = 0.0001 and 0.0002, respectively). Using multivariate analysis examining factors affecting recurrence and survival, we found that previous non-invasive bladder tumour history was associated with a significantly reduced risk of mortality and recurrence (Hazard ratio of 0.7 for all risks, P = 0.0002). CONCLUSION: Our retrospective study suggests that patients with non-invasive urothelial carcinoma of the bladder that progress to muscle invasion and require radical cystectomy appear to have better pathologic and clinical outcome than patients presenting with clinical muscle invasive disease de novo.

Active Surveillance Magnetic Resonance Imaging Study (ASIST): Results of a Randomized Multicenter Prospective Trial.

BACKGROUND AND OBJECTIVE: This study aimed to determine, in men recently diagnosed with grade group 1 (GG1) prostate cancer, if magnetic resonance imaging (MRI) with targeted biopsy could identify a greater proportion of men with GG ≥2 cancer on their confirmatory biopsy compared with systematic biopsies. The study was registered with www.clinicaltrials.gov (NCT01354171). DESIGN, SETTING, AND PARTICIPANTS: This study is a prospective, randomized, multicenter, open-label trial. Eligible patients were men diagnosed with GG1 cancer within 1 yr prior to study entry in whom a confirmatory biopsy was indicated. Patients were randomized to 12-core systematic biopsy or MRI with systematic and targeted biopsy using the Artemis fusion targeting system. The primary end point was the proportion upgraded to GG ≥2 in each arm. RESULTS AND LIMITATIONS: In total, 296 men were registered and 273 randomized. Of the MRI group, 64% had a region of interest. No difference was observed in the rate of GG ≥2 upgrading (the intent-to-treat population, p=0.7, and per-protocol [PP] population, p=0.4), GG ≥2 upgrading within each stratum separately, or GG ≥3. After central pathology review, upgrading was observed in 36/132 (27%) men in the systematic biopsy arm and 42/127 (33%) men in the MRI arm (p=0.3). Upgrading was seen in 19/137 (14%) patients in the MRI arm on targeted biopsy alone (median, 2 cores) compared with 31/136 (23%) in the systematic biopsy arm (median, 12 cores; p=0.09). In the MRI arm, 8/127 (6.5%) patients had GG ≥2 disease identified on targeted biopsy, but ≤GG1 on the systematic biopsy, and 10/127 (7.9%) patients had GG ≥2 disease identified by systematic biopsy but ≤GG1 on targeted biopsy. Significant differences in upgrading on targeted biopsies were seen between sites, likely reflecting different levels of expertise with the targeted biopsy technique. CONCLUSIONS: The addition of MRI with targeted biopsies to systematic biopsies did not significantly increase the upgrading rate compared with systematic biopsy alone. Furthermore, 2-core targeted biopsies alone resulted in a nonsignificant trend to less upgrading than 12-core systematic biopsy (p=0.09). In men on active surveillance, targeted biopsies identify most, but not all, clinically significant cancers.

Adjuvant chemotherapy for upper-tract urothelial carcinoma treated with nephroureterectomy: assessment of adequate renal function and influence on outcome.

OBJECTIVES: Upper-tract urothelial carcinoma (UTUC) is associated with poor outcomes. Our aim was to assess adequacy of renal function and evaluate the role of adjuvant chemotherapy (AC) in patients with UTUC treated by radical nephroureterectomy (RNU) in a universal health care system. MATERIALS AND METHODS: Retrospective data from 1,029 patients treated with RNU across 10 Canadian academic centers were collected. Tested variables included various clinico-pathological parameters, the use of perioperative chemotherapy, preoperative and postoperative creatinine values, and estimated glomerular filtration rates (eGFR). Univariable and multivariable Cox regression models addressed overall survival and disease-specific survival after surgery. Kaplan-Meier survival curves were used to compare outcomes in patients who received or did not receive AC. RESULTS: Median age of patients was 70 years with a median follow-up of patients who were alive of 26 months. The median preoperative and postoperative eGFR rates were 59 mL/min/1.73 m(2) and 47 mL/min/1.73 m(2), respectively. Using a cutoff eGFR of 60, 49% of all the patients and 48% of the patients with ≥ pT3 or pTxN+ or both diseases would have been eligible for cisplatin-based chemotherapy preoperatively and only 18% and 21% of the patients, respectively remained eligible postoperatively. Of the patients who received AC, 75% had an eGFR<60. On multivariate analysis, AC was not prognostic for improved overall survival or disease-specific survival. CONCLUSIONS: Chronic kidney disease is common in patients with UTUC. Following RNU, 57% of the high-risk patients with good preoperative renal function became ineligible for cisplatin-based chemotherapy. Use of AC did not translate into improved survival. Whether this is due to inherent biases of retrospective analysis, limited efficacy of AC in patients with UTUC, or use of suboptimal regimen or dose because of poor postoperative renal function requires further evaluation.

Age ≥ 80 years is independently associated with survival outcomes after radical cystectomy: results from the Canadian Bladder Cancer Network Database.

OBJECTIVES: The role of advanced age as an independent prognostic factor for clinical outcomes after radical cystectomy is controversial. The objective of the current study was to assess the associations between age and clinical outcomes in a large, multi-institutional series of patients treated with radical cystectomy for bladder cancer. MATERIALS AND METHODS: Institutional radical cystectomy databases containing detailed information on bladder cancer patients treated between 1993 and 2008 were obtained from 8 academic centers in Canada. Data were collected on 2,287 patients and combined into a relational database formatted with patient characteristics, pathologic characteristics, recurrence status, and survival status. Patient age was coded as <60 years, 60-69 years, 70-79 years, or ≥ 80 years. Clinical outcomes were 30-day mortality, 90-day mortality, overall survival (OS), disease-specific survival (DSS), and recurrence-free survival (RFS). Logistic regression and Cox proportional hazards regression analysis were used to analyze survival data. RESULTS: Five hundred fifty-seven (24.6%), 679 (30.0%), 846 (37.4%), and 181 (8.0%) patients were <60 years, 60-69 years, 70-79 years, and ≥ 80 years, respectively. Increased age was associated with decreased utilization rates of neoadjuvant chemotherapy (P = 0.0143), adjuvant chemotherapy (P < 0.0001), and continent urinary diversion (P < 0.0001) as well as advanced pathologic tumor stage (P = 0.0003), increased positive surgical margins (P < 0.0001), and lymphovascular invasion (P = 0.0335). Compared with patients < 60 years, multivariate regression analysis showed that age ≥ 80 years was independently associated with 90-day mortality (OR 2.98, 95% CI 1.22-7.30), OS (HR 2.03, 95% CI 1.51-2.75), DSS (HR 1.56, 95% CI 1.09-2.24), and RFS (HR 2.06, 95% CI 1.57-2.70). CONCLUSIONS: Age ≥ 80 years at the time of radical cystectomy was independently associated with adverse survival outcomes. These data suggest that increased chronologic age should be considered in clinical trial design and in nomograms predicting survival.

Hydrolytic activity in baker's yeast limits the yield of asymmetric 3-oxo ester reduction.

Microbial reductions of ketones hold great potential for the production of enantiopure alcohols, as long as highly selective redox enzymes are not interfered with by competing activities. During reduction of ethyl 3-oxobutanoate by baker's yeast (Saccharomyces cerevisiae) to ethyl (S)-3-hydroxybutanoate, a high enantiomeric excess (> 99%) can be obtained. However, reported yields do not exceed 50-70%. In this article, three main causes are shown to be responsible for these low to moderate yields. These are evaporation of the substrate and product esters, absorption or adsorption of the two esters by the yeast cells and hydrolysis of the two esters by yeast enzymes. The hydrolysis products are further metabolized by the yeast. By reducing the evaporation and absorption losses, the reduction yield can easily be improved to about 85%. Improvement of the efficiency of the reduction and hence the reduction/hydrolysis ratio should lead to a further increase in yield.

Influence of the ethanol and glucose supply rate on the rate and enantioselectivity of 3-oxo ester reduction by baker's yeast.

Baker's-yeast-mediated reductions of ketones hold great potential for the industrial production of enantiopure alcohols. In this article we describe the stoichiometry and kinetics of asymmetric ketone reduction by cell suspensions of bakers' yeast (Saccharomyces cerevisiae). A system for quantitative analysis of 3-oxo ester reduction was developed and allowed construction of full mass and redox balances as well as determination of the influence of different process parameters on aerobic ketone reduction. The nature of the electron donor (ethanol or glucose) and its specific consumption rate by the biomass (0-1 mol.kg dw(-1).h(-1)) affected the overall stoichiometry and rate of the process and the final enantiomeric excess of the product. Excess glucose as the electron donor, i.e. a very high consumption rate of glucose, resulted in a high rate of alcoholic fermentation, oxygen consumption, and biomass formation and therefore causing low efficiency of glucose utilization. Controlled supply of the electron donor at the highest rates applied prevented alcoholic fermentation but still resulted in biomass formation and a high oxygen requirement, while low rates resulted in a more efficient use of the electron donor. Low supply rates of ethanol resulted in biomass decrease while low supply rates of glucose provided the most efficient strategy for electron donor provision and yielded a high enantiomeric excess of ethyl (S)-3-hydroxybutanoate. In contrast to batchwise conversions with excess glucose as the electron donor, this strategy prevented by-product formation and biomass increase, and resulted in a low oxygen requirement.

Enhancement of Exopolysaccharide Production by Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772 with a Simplified Defined Medium.

The aim of this work was to investigate the medium requirements for growth and production of exopolysaccharides by Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772. The strain was grown in batch cultures on a chemically defined medium, and the technique of single omission of medium components was applied to determine the nutritional requirements. The omission of aspartic acid, glutamic acid, or glycine affected growth only slightly, and the omission of glutamine, asparagine, or threonine resulted in a stronger reduction of the growth. All the other amino acids were essential. Multiple omissions of amino acids caused an almost complete loss of growth. L. delbrueckii subsp. bulgaricus required only riboflavin, calcium pantothenate, and nicotinic acid as individual vitamins. Surprisingly, when only these vitamins were present in the medium and other vitamins were not, less growth was observed than in the complete medium but the amount of exopolysaccharide produced was significantly greater. These observations were studied in more detail with a simplified defined medium in which L. delbrueckii subsp. bulgaricus was able to grow and produce exopolysaccharides. Although the final optical density in the simplified medium was lower, the production of exopolysaccharides was about twofold higher than in the complete medium.