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"Sze, David Y"
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OR Practice--A Queueing Model for Telephone Operator Staffing
by
Sze, David Y
in
683 nonstationary inputs, abandonments, and reattempts
,
698 nonabsolute priorities for nonhomogeneous traffic
,
queues with large (100–300) server teams
1984
This paper describes a queueing model of telephone operator staffing and the application of the model. The Bell System has used the model to reduce the cost of meeting its service criteria, for planning purposes, and to help explain to regulatory agencies changes in service measurement criteria. The model deals with large server team sizes, bimodal service time distributions, nonstationary arrivals, customer abandonments and reattempts, and certain priority queueing structures.
Journal Article
A Queueing Model for Telephone Operator Staffing
1984
This paper describes a queueing model of telephone operator staffing and the application of the model. The Bell System has used the model to reduce the cost of meeting its service criteria, for planning purposes, and to help explain to regulatory agencies changes in service measurement criteria. The model deals with large server team sizes, bimodal service time distributions, nonstationary arrivals, customer abandonments and reattempts, and certain priority queueing structures.
Journal Article
A Queuing Model for Telephone Operator Staffing
1984
In the Bell Telephone System, service criteria for telephone operator staffing are based on target delays. The goal is to ensure that customers receive good levels of service during normal load times and to protect against very poor service during peak load periods. The system's staffing problem cannot be solved using standard queuing models because of: 1. the large number of servers involved, 2. bimodal service time distributions, 3. nonstationarity of customer arrivals, 4. customer abandonment and reattempts for service, and 5. nonpreemptive priority rules for service. Therefore, a new queuing model was developed to generate staffing tables for each operating system and range of service times per customer. The tables specify the number of servers required to meet given load levels under average delay criteria, based on load forecasts derived from historical data, usage trends, and traffic growth patterns. The staffing tables are then used to arrange individual operators' schedules to meet service requirements per half hour.
Journal Article
International recommendations for personalised selective internal radiation therapy of primary and metastatic liver diseases with yttrium-90 resin microspheres
2021
PurposeA multidisciplinary expert panel convened to formulate state-of-the-art recommendations for optimisation of selective internal radiation therapy (SIRT) with yttrium-90 (90Y)-resin microspheres.MethodsA steering committee of 23 international experts representing all participating specialties formulated recommendations for SIRT with 90Y-resin microspheres activity prescription and post-treatment dosimetry, based on literature searches and the responses to a 61-question survey that was completed by 43 leading experts (including the steering committee members). The survey was validated by the steering committee and completed anonymously. In a face-to-face meeting, the results of the survey were presented and discussed. Recommendations were derived and level of agreement defined (strong agreement ≥ 80%, moderate agreement 50%–79%, no agreement ≤ 49%).ResultsForty-seven recommendations were established, including guidance such as a multidisciplinary team should define treatment strategy and therapeutic intent (strong agreement); 3D imaging with CT and an angiography with cone-beam-CT, if available, and 99mTc-MAA SPECT/CT are recommended for extrahepatic/intrahepatic deposition assessment, treatment field definition and calculation of the 90Y-resin microspheres activity needed (moderate/strong agreement). A personalised approach, using dosimetry (partition model and/or voxel-based) is recommended for activity prescription, when either whole liver or selective, non-ablative or ablative SIRT is planned (strong agreement). A mean absorbed dose to non-tumoural liver of 40 Gy or less is considered safe (strong agreement). A minimum mean target-absorbed dose to tumour of 100–120 Gy is recommended for hepatocellular carcinoma, liver metastatic colorectal cancer and cholangiocarcinoma (moderate/strong agreement). Post-SIRT imaging for treatment verification with 90Y-PET/CT is recommended (strong agreement). Post-SIRT dosimetry is also recommended (strong agreement).ConclusionPractitioners are encouraged to work towards adoption of these recommendations.
Journal Article
Global trends in the consumption of benzodiazepines and Z-drugs in 67 countries and regions from 2008 to 2018: a sales data analysis
2023
Abstract
Study Objectives
To investigate the trends in the consumption of benzodiazepines (BZDs) and Z-drugs at global, regional, and national levels from 2008 to 2018, across 67 countries and regions.
Methods
This cross-sectional descriptive study investigated the consumption of BZDs and Z-drugs analyzed by global pharmaceutical sales data from the IQVIA-Multinational Integrated Data Analysis System database between 2008 and 2018. Consumption was measured in defined daily dose (DDD) per 1000 inhabitants per day (DDD/TID). The global, regional, and national trends were estimated using linear mixed models. Additional analyses were conducted by grouping countries by income level. The association between consumption and Gross Domestic Product (GDP) and the prevalence of different medical conditions was explored in univariable linear models.
Results
BZD consumption decreased annually by −1.88% (95% CI: −2.27%, −1.48%), and Z-drugs increased by + 3.28% (+2.55%, +4.01%). In 2008, the top ten countries for BZD and Z-drug consumption were all European, ranging from 63.69 to 128.24 DDD/TID. Very low levels were found in Russia, Kuwait, United Arab Emirates, Saudi Arabia, French West Africa, and the Philippines, with DDD/TID < 1. The consumption in high-income countries was much higher than in middle-income countries. The results showed that increased consumption of BZDs and Z-drugs was statistically associated (p < 0.05) with higher GDP and increased prevalence of anxiety, self-harm, neurological disorders, chronic respiratory diseases, cardiovascular diseases, and cancers.
Conclusions
Distinct differences in consumption and trends of BZDs and Z-drugs were found across different countries and regions. Further exploration is needed to understand the association and safety of the use of BZDs and Z-drugs in patients with comorbidities.
Graphical Abstract
Graphical Abstract
Journal Article
177LuLu-PSMA-617 versus cabazitaxel in patients with metastatic castration-resistant prostate cancer (TheraP): a randomised, open-label, phase 2 trial
by
Rutherford, Natalie K
,
Kirkwood, Ian D
,
Lin, Peter
in
Administration, Intravenous
,
Adverse events
,
Aged
2021
Lutetium-177 [177Lu]Lu-PSMA-617 is a radiolabelled small molecule that delivers β radiation to cells expressing prostate-specific membrane antigen (PSMA), with activity and safety in patients with metastatic castration-resistant prostate cancer. We aimed to compare [177Lu]Lu-PSMA-617 with cabazitaxel in patients with metastatic castration-resistant prostate cancer.
We did this multicentre, unblinded, randomised phase 2 trial at 11 centres in Australia. We recruited men with metastatic castration-resistant prostate cancer for whom cabazitaxel was considered the next appropriate standard treatment. Participants were required to have adequate renal, haematological, and liver function, and an Eastern Cooperative Oncology Group performance status of 0–2. Previous treatment with androgen receptor-directed therapy was allowed. Men underwent gallium-68 [68Ga]Ga-PSMA-11 and 2-flourine-18[18F]fluoro-2-deoxy-D-glucose (FDG) PET-CT scans. PET eligibility criteria for the trial were PSMA-positive disease, and no sites of metastatic disease with discordant FDG-positive and PSMA-negative findings. Men were randomly assigned (1:1) to [177Lu]Lu-PSMA-617 (6·0–8·5 GBq intravenously every 6 weeks for up to six cycles) or cabazitaxel (20 mg/m2 intravenously every 3 weeks for up to ten cycles). The primary endpoint was prostate-specific antigen (PSA) response defined by a reduction of at least 50% from baseline. This trial is registered with ClinicalTrials.gov, NCT03392428.
Between Feb 6, 2018, and Sept 3, 2019, we screened 291 men, of whom 200 were eligible on PET imaging. Study treatment was received by 98 (99%) of 99 men randomly assigned to [177Lu]Lu-PSMA-617 versus 85 (84%) of 101 randomly assigned to cabazitaxel. PSA responses were more frequent among men in the [177Lu]Lu-PSMA-617 group than in the cabazitaxel group (65 vs 37 PSA responses; 66% vs 37% by intention to treat; difference 29% (95% CI 16–42; p<0·0001; and 66% vs 44% by treatment received; difference 23% [9–37]; p=0·0016). Grade 3–4 adverse events occurred in 32 (33%) of 98 men in the [177Lu]Lu-PSMA-617 group versus 45 (53%) of 85 men in the cabazitaxel group. No deaths were attributed to [177Lu]Lu-PSMA-617.
[177Lu]Lu-PSMA-617 compared with cabazitaxel in men with metastatic castration-resistant prostate cancer led to a higher PSA response and fewer grade 3 or 4 adverse events. [177Lu]Lu-PSMA-617 is a new effective class of therapy and a potential alternative to cabazitaxel.
Prostate Cancer Foundation of Australia, Endocyte (a Novartis company), Australian Nuclear Science and Technology Organization, Movember, The Distinguished Gentleman's Ride, It's a Bloke Thing, and CAN4CANCER.
Journal Article
PSMA and FDG-PET as predictive and prognostic biomarkers in patients given 177LuLu-PSMA-617 versus cabazitaxel for metastatic castration-resistant prostate cancer (TheraP): a biomarker analysis from a randomised, open-label, phase 2 trial
2022
Previously, results from the TheraP trial showed that treatment with lutetium-177 [177Lu]Lu-PSMA-617 improved frequency of prostate-specific antigen (PSA) response rate and progression-free survival compared with cabazitaxel in men with metastatic castration-resistant prostate cancer. In this study, we aimed to analyse gallium-68 [68Ga]Ga-PSMA-11 PET (PSMA-PET) and 2-[18F]fluoro-2-deoxy-D-glucose PET (FDG-PET) imaging parameters as predictive and prognostic biomarkers in this patient population.
TheraP was a multicentre, open-label, randomised phase 2 trial that recruited men with metastatic castration-resistant prostate cancer after treatment with docetaxel who were suitable for cabazitaxel from 11 hospitals in Australia. Participants were required to be 18 years old or older; have adequate haematological, renal, and liver function; and an Eastern Cooperative Oncology Group performance status of 0–2. Participants were randomly assigned (1:1) using a centralised system using minimisation with a random component and that stratified patients by disease burden, previous treatment with enzalutamide or abiraterone, and study site. Patients were either given cabazitaxel (20 mg/m2 intravenously every 3 weeks for up to ten cycles) or [177Lu]Lu-PSMA-617 (6·0–8·5 GBq intravenously every 6 weeks for up to six cycles). The primary study endpoint, analysed previously, was PSA response rate. The prespecified tertiary study endpoint was association between total tumour quantitative parameters on PSMA-PET, FDG-PET, and baseline characteristics with clinical outcomes. A SUVmean of 10 or higher on PSMA-PET was evaluated as a predictive biomarker for response to [177Lu]Lu-PSMA-617 versus cabazitaxel. A metabolic tumour volume (MTV) of 200 mL or higher on FDG-PET was tested as a prognostic biomarker. Both cutoff points were prespecified. The analysis was intention-to-treat, using logistic regression. This trial is registered with ClinicalTrials.gov, NCT03392428.
200 patients were randomly assigned between Feb 6, 2018, and Sept 3, 2019. 101 men were assigned to the cabazitaxel group and 99 were assigned to the [177Lu]Lu-PSMA-617 group. The median follow-up at data cutoff of July 20, 2020, was 18·4 months (IQR 12·8–21·8). 35 (35%) of 99 men who were assigned [177Lu]Lu-PSMA-617 and 30 (30%) of 101 men who were assigned cabazitaxel had high PSMA uptake (SUVmean of ≥10). Odds of PSA response to [177Lu]Lu-PSMA-617 versus cabazitaxel were significantly higher for men with SUVmean of 10 or higher compared with those with SUVmean of less than 10 (odds ratio [OR] 12·19 [95% CI 3·42–58·76] vs 2·22 [1·11–4·51]; padj=0·039 for treatment-by-SUVmean interaction). PSA response rate for [177Lu]Lu-PSMA-617 compared with cabazitaxel was 32 (91% [95% CI 76–98]) of 35 men versus 14 (47% [29–65]) of 30 men in patients with SUVmean of 10 or higher, and 33 (52% [39–64]) of 64 men versus 23 (32% [22–45]) of 71 men in those with SUVmean of less than 10. High-volume disease on FDG-PET (MTV ≥200 mL) was seen in 30 (30%) of 99 men who were assigned [177Lu]Lu-PSMA-617 and 30 (30%) of 101 men who were assigned cabazitaxel. PSA response rate for both treatment groups combined for FDG-PET MTV of 200 mL or higher versus FDG-PET MTV of less than 200 mL was 23 (38% [95% CI 26–52]) of 60 men versus 79 (56% [48–65]) of 140 men (OR 0·44, 95% CI 0·23–0·84; padj=0·035).
In men with metastatic castration-resistant prostate cancer, PSMA-PET SUVmean was predictive of higher likelihood of favourable response to [177Lu]Lu-PSMA-617 than cabazitaxel, which provides guidance for optimal [177Lu]Lu-PSMA-617 use. High FDG-PET MTV was associated with lower responses regardless of randomly assigned treatment, warranting further research for treatment intensification. A strength of this analysis is the validation of pre-specified cutpoints within a multicentre, randomised, controlled trial. Quantitative PET parameters used, however, require specialised software and are not yet routinely available in most clinics.
Prostate Cancer Foundation of Australia, Endocyte (a Novartis Company), Australian Nuclear Science and Technology Organisation, Movember Foundation, It's a Bloke Thing, CAN4CANCER, The Distinguished Gentleman's Ride.
Journal Article
A PHGDH inhibitor reveals coordination of serine synthesis and one-carbon unit fate
2016
A quantitative high-throughput screen identified an inhibitor of phosphoglycerate dehydrogenase (PHGDH), a key enzyme for serine synthesis. This inhibitor limits one-carbon unit availability for nucleotide synthesis.
Serine is both a proteinogenic amino acid and the source of one-carbon units essential for
de novo
purine and deoxythymidine synthesis. In the canonical pathway of glucose-derived serine synthesis,
Homo sapiens
phosphoglycerate dehydrogenase (PHGDH) catalyzes the first, rate-limiting step. Genetic loss of PHGDH is toxic toward PHGDH-overexpressing breast cancer cell lines even in the presence of exogenous serine. Here, we used a quantitative high-throughput screen to identify small-molecule PHGDH inhibitors. These compounds reduce the production of glucose-derived serine in cells and suppress the growth of PHGDH-dependent cancer cells in culture and in orthotopic xenograft tumors. Surprisingly, PHGDH inhibition reduced the incorporation into nucleotides of one-carbon units from glucose-derived and exogenous serine. We conclude that glycolytic serine synthesis coordinates the use of one-carbon units from endogenous and exogenous serine in nucleotide synthesis, and we suggest that one-carbon unit wasting thus may contribute to the efficacy of PHGDH inhibitors
in vitro
and
in vivo
.
Journal Article
Lipid-Based Self-Microemulsion of Niclosamide Achieved Enhanced Oral Delivery and Anti-Tumor Efficacy in Orthotopic Patient-Derived Xenograft of Hepatocellular Carcinoma in Mice
2024
We previously identified niclosamide as a promising repurposed drug candidate for hepatocellular carcinoma (HCC) treatment. However, it is poorly water soluble, limiting its tissue bioavailability and clinical application. To overcome these challenges, we developed an orally bioavailable self-microemulsifying drug delivery system encapsulating niclosamide (Nic-SMEDDS).
Nic-SMEDDS was synthesized and characterized for its physicochemical properties, in vivo pharmacokinetics and absorption mechanisms, and in vivo therapeutic efficacy in an orthotopic patient-derived xenograft (PDX)-HCC mouse model. Niclosamide ethanolamine salt (NEN), with superior water solubility, was used as a positive control.
Nic-SMEDDS (5.6% drug load) displayed favorable physicochemical properties and drug release profiles in vitro. In vivo, Nic-SMEDDS displayed prolonged retention time and plasma release profile compared to niclosamide or NEN. Oral administration of Nic-SMEDDS to non-tumor bearing mice improved niclosamide bioavailability and C
by 4.1- and 1.8-fold, respectively, compared to oral niclosamide. Cycloheximide pre-treatment blocked niclosamide absorption from orally administered Nic-SMEDDS, suggesting that its absorption was facilitated through the chylomicron pathway. Nic-SMEDDS (100 mg/kg, bid) showed greater anti-tumor efficacy compared to NEN (200 mg/kg, qd); this correlated with higher levels (
< 0.01) of niclosamide, increased caspase-3, and decreased Ki-67 in the harvested PDX tissues when Nic-SMEDDS was given. Biochemical analysis at the treatment end-point indicated that Nic-SMEDDS elevated lipid levels in treated mice.
We successfully developed an orally bioavailable formulation of niclosamide, which significantly enhanced oral bioavailability and anti-tumor efficacy in an HCC PDX mouse model. Our data support its clinical translation for the treatment of solid tumors.
Journal Article