Engineering of Escherichia coli strains for plasmid biopharmaceutical production: Scale-up challenges

Plasmid-based vaccines and therapeutics have been making their way into the clinic in the last years. The existence of cost-effective manufacturing processes capable of delivering high amounts of high-quality plasmid DNA (pDNA) is essential to generate enough material for trials and support future commercialization. However, the development of pDNA manufacturing processes is often hampered by difficulties in predicting process scale performance of Escherichia coli cultivation on the basis of results obtained at lab scale. This paper reports on the differences observed in pDNA production when using shake flask and bench-scale bioreactor cultivation of E. coli strains MG1655ΔendAΔrecA and DH5α in complex media with 20 g/L of glucose. MG1655ΔendAΔrecA produced 5-fold more pDNA (9.8 mg/g DCW) in bioreactor than in shake flask (1.9 mg/g DCW) and DH5α produced 4-fold more pDNA (8 mg/g DCW) in bioreactor than in shake flask (2 mg/g DCW). Accumulation of acetate was also significant in shake flasks but not in bioreactors, a fact that was attributed to a lack of control of pH.     

The benefits of redesigning Benin's vaccine supply chain

Introduction

New vaccine introductions have put strains on vaccine supply chains around the world. While increasing storage and transportation may be the most straightforward options, it is also important to consider what financial and operational benefits can be incurred. In 2012, suboptimal vaccine coverage and impending vaccine introductions prompted the Republic of Benin's Ministry of Health (MOH) to explore ways to improve their vaccine supply chain.

Methods

Working alongside the Beninese MOH, we utilized our computational model, HERMES, to explore the impact on cost and vaccine availability of three possible options: (1) consolidating the Commune level to a Health Zone level, (2) removing the Commune level completely, and (3) removing the Commune level and expanding to 12 Department Stores. We also analyzed the impact of adding shipping loops during delivery.

Results

At baseline, new vaccine introductions without any changes to the current system increased the logistics cost per dose ($0.23 to $0.26) and dropped the vaccine availability to 71%. While implementing the Commune level removal scenario had the same capital costs as implementing the Health Zone scenario, the Health Zone scenario had lower operating costs. This increased to an overall cost savings of $504,255 when implementing shipping loops.

Discussion

The best redesign option proved to be the synergistic approach of converting to the Health Zone design and using shipping loops (serving ten Health Posts/loop). While a transition to either redesign or only adding shipping loops was beneficial, implementing a redesign option and shipping loops can yield both lower capital expenditures and operating costs.     

A history of alcohol dependence augments HIV-associated neurocognitive deficits in persons aged 60 and older

Excessive alcohol use is common among people living with HIV. Given the growing prevalence of older HIV+ adults and observations indicating higher risk for neurocognitive impairment in older adults with either HIV infection or alcoholism, an increased understanding of their combined impact in the context of this increasingly aged population is crucial. We conducted comprehensive neurocognitive assessment in 112 older HIV+ individuals aged 50 to 69 years. Regression analyses were conducted to examine the interaction between age and the presence of lifetime alcohol dependence on neurocognitive measures, controlling for years of education, hepatitis C serostatus, and lifetime non-alcohol substance use disorder. Significant interactions of age and alcohol dependence history were found for global neurocognitive function, which was driven by the domains of executive function, processing speed, and semantic memory. Follow-up analyses indicated adverse effects of alcohol use history on neurocognitive measures that were evident only in HIV+ individuals 60 years and older. While mounting evidence in younger cohorts indicates adverse synergistic HIV/alcohol effects on neurocognitive function, our novel preliminary findings in this elderly HIV+ cohort demonstrated the importance of even a relatively distant alcohol use history on the expression of HIV-associated neurocognitive disorders that may not become apparent until much later in life.     

γ-Aminobutyric acid (GABA) concentration inversely correlates with basal perfusion in human occipital lobe

Commonly used neuroimaging approaches in humans exploit hemodynamic or metabolic indicators of brain function. However, fundamental gaps remain in our ability to relate such hemo-metabolic reactivity to neurotransmission, with recent reports providing paradoxical information regarding the relationship among basal perfusion, functional imaging contrast, and neurotransmission in awake humans. Here, sequential magnetic resonance spectroscopy (MRS) measurements of the primary inhibitory neurotransmitter, γ-aminobutyric acid (GABA+macromolecules normalized by the complex N-acetyl aspartate-N-acetyl aspartyl glutamic acid: [GABA⁺]/[NAA–NAAG]), and magnetic resonance imaging (MRI) measurements of perfusion, fractional gray-matter volume, and arterial arrival time (AAT) are recorded in human visual cortex from a controlled cohort of young adult male volunteers with neurocognitive battery-confirmed comparable cognitive capacity (3 T; n=16; age=23±3 years). Regression analyses reveal an inverse correlation between [GABA⁺]/[NAA–NAAG] and perfusion (R=−0.46; P=0.037), yet no relationship between AAT and [GABA⁺]/[NAA–NAAG] (R=−0.12; P=0.33). Perfusion measurements that do not control for AAT variations reveal reduced correlations between [GABA⁺]/[NAA–NAAG] and perfusion (R=−0.13; P=0.32). These findings largely reconcile contradictory reports between perfusion and inhibitory tone, and underscore the physiologic origins of the growing literature relating functional imaging signals, hemodynamics, and neurotransmission.     

The adrenal psoas sign: surgical outcomes following a simple technique to maximize removal of extracortical adrenal tissue during bilateral laparoscopic adrenalectomy

Background

Bilateral laparoscopic adrenalectomy (BLA) is an effective therapy for the management of persistent hypercortisolism in patients after failed transphenoidal pituitary tumor resection for Cushing’s disease. Extracortical adrenal tissue has been identified as a source of persistent hypercortisolism and, if not resected along with both adrenal glands, may lead to treatment failure. We report a reliable and reproducible technique called the “psoas sign” for BLA in patients with Cushing’s disease which reduces the likelihood of retained extra-adrenal cortical rests and may reduce intraoperative complications.

Methods

A 16-year retrospective review of all consecutive patients who underwent transabdominal BLA at a single tertiary care center was performed. All patients underwent BLA utilizing the psoas sign technique and all procedures were performed replicating these predetermined surgical steps: (1) Identification of the inferior pole of the gland. (2) Identification of the inferior aspect of the adreno-caval groove on the right or the adrenal vein/renal vein confluence on the left. (3) Division of the adrenal vein. (4) Dissection and removal of the adrenal gland with clearance of all retroperitoneal fat overlying the psoas muscle.

Results

Between October 1996 and December 2012, 92 patients underwent BLA for refractory Cushing’s disease. Patients were predominantly female (90 %) with a median age of 40 years (17–71). There were 3 intraoperative complications (3.2 %), 2 conversions (2.2 %), and 1 death (1.09 %). Four patients were identified as having extracortical rests of adrenal tissue within the retroperitoneal fat (4.3 %). Mean operative time was 272 min (±79.25, n = 68) and median estimated blood loss was 50 mL (10–800 mL).

Conclusions

The psoas sign technique provides a clear view of the adrenal fossa and facilitates careful dissection of the anatomic planes around the adrenal gland. This technique is feasible, reproducible and in our experience allows for safe removal of both adrenal glands and all surrounding extracortical adrenal tissue.     

Hospital-acquired conditions after bariatric surgery: we can predict,but can we prevent?

Background

Centers for Medicare and Medicaid Services initiated a non-payment policy for certain hospital-acquired conditions (HACs) in 2008. This study aimed to determine the rate of the three most common HACs (surgical site infection (SSI), urinary tract infection (UTI), and venous thromboembolism (VTE)) among bariatric surgery patients. Additionally, the association of HACs with patient factors and the effect of HACs on post-operative outcomes were investigated.

Methods

Patients over 18 years with a body mass index (BMI) ≥35 who underwent bariatric surgery were identified using the American College of Surgeons’ National Surgical Quality Improvement Program (ACS-NSQIP) database (2005–2012). Patients were grouped into two categories: HAC versus no HAC patients and baseline characteristics and outcomes, including 30-day mortality, reoperation, and mean length of stay (LOS) were compared. Multivariable logistic regression analysis was performed to identify the risk factors for developing a HAC.

Results

98,553 patients were identified, 2,809 (2.9 %) developed at least one HACs. SSI was the most common HAC (1.8 %), followed by UTI (0.7 %) and VTE (0.4 %). The rate of these HACs significantly decreased from 4.6 % in 2005–2006 to 2.5 % in 2012 (p < 0.001). Laparoscopic gastric banding was associated with the lowest rates of HAC (1.3 %) and open gastric bypass with the highest (8.0 %). HAC patients had significantly higher rates of in-hospital mortality (0.8 vs. 0.1 %, p < 0.001) and LOS (3.9 vs. 2.1 days, p < 0.001). On adjusted analysis, open GBP patients had 5.36-fold higher odds of developing a HAC. Interestingly, the presence of a resident surgeon 7–11 years post graduation was associated with significantly increased odds of HACs (1.86, 1.50–2.31, p < 0.001).

Conclusion

Our data demonstrate a strong correlation between these three HACs following bariatric surgery and factors intrinsic to the bariatric patient population. This calls into question the non-payment policy for inherent patient factors on which they cannot have impact. These findings are important to help inform health care policy decisions regarding access to care for bariatric surgery patients.