Convenient non-invasive electrochemical techniques to monitor microbial processes: current state and perspectives.

Real-time electrochemical monitoring in bioprocesses is an improvement over existing systems because it is versatile and provides more information to the user than periodic measurements of cell density or metabolic activity. Real-time electrochemical monitoring provides the ability to monitor the physiological status of actively growing cells related to electron transfer activity and potential changes in the proton gradient of the cells. Voltammetric and amperometric techniques offer opportunities to monitor electron transfer reactions when electrogenic microbes are used in microbial fuel cells or bioelectrochemical synthesis. Impedance techniques provide the ability to monitor the physiological status of a wide range of microorganisms in conventional bioprocesses. Impedance techniques involve scanning a range of frequencies to define physiological activity in terms of equivalent electrical circuits, thereby enabling the use of computer modeling to evaluate specific growth parameters. Electrochemical monitoring of microbial activity has applications throughout the biotechnology industry for generating real-time data and offers the potential for automated process controls for specific bioprocesses.

In-situ electrochemical analysis of microbial activity.

Microbes have a wide range of metabolic capabilities available that makes them industrially useful organisms. Monitoring these metabolic processes is a crucial component in efficient industrial application. Unfortunately, monitoring these metabolic processes can often be invasive and time consuming and expensive, especially within an anaerobic environment. Electrochemical techniques, such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) offer a non-invasive approach to monitor microbial activity and growth. EIS and CV were used to monitor Clostridium phytofermentans, an anaerobic and endospore-forming bacterium. C. phytofermentans ferments a wide range of sugars into hydrogen, acetate, and ethanol as fermentation by-products. For this study, both traditional microbiological and electrochemical techniques were used to monitor the growth of C. phytofermentans and the formation of fermentation products. An irreversible reduction peak was observed using CV beginning at mid-logarithmic phase of growth. This peak was associated with C. phytofermentans and not the spent medium and was indicative of a decrease in carbon and energy sources to the cells. Additionally, EIS analysis during growth provided information related to increased charge transfer resistance of the culture also as a function of carbon and energy source depletion. Results demonstrate that CV and EIS are useful tools in the monitoring the physiological status of bioprocesses.

Value of gastrografin in adhesive small bowel obstruction.

BACKGROUND: Small bowel obstruction (SBO) from adhesive disease presents great burden for the healthcare system. Some groups have reported water soluble contrast agents (WSCA) protocols, but published studies are underpowered. This study introduces a WSCA protocol to improve outcomes and streamline patient care. STUDY DESIGN: The study ran July 1, 2013-June 30, 2015, at Kaiser Permanente San Diego; protocol started July 1, 2014. Data was collected prospectively, on an intention to treat basis. We excluded patients whose SBO were not due to adhesive disease. Protocol included nasogastric tube, intravenous resuscitation, liquid docusate, and gastrografin study if symptoms persisted at 24 h. Colon contrast determined resolution vs operative consideration. Primary outcomes were operative rates and hospital length of stay (LOS). RESULTS: Seven hundred fifteen were patients admitted with SBO; after exclusions there were 261 pre-protocol and 243 protocol patients. One hundred sixty patients resolved within 24 h; 96% of remaining patients stayed on protocol (n = 154). After WSCA protocol began, 15.6% required an operation, compared to 19.8% of pre-protocol patients (NS). The WSCA protocol significantly decreased the time to surgery (2.8 vs 4.88 days, p = 0.03), and the LOS of operated patients (9.51 vs 15.78 days, p = 0.02). CONCLUSIONS: A standardized SBO protocol using WSCA significantly decreased time to operation and hospital LOS. This approach improves utilization of resources and may improve outcomes. More work should be done to investigate the positive effects of WSCA protocol for patients with SBO.

Validation of an updated approach to preoperative cardiac risk assessment in vascular surgery.

To validate a more selective approach to cardiac assessment which consisted of limiting stress testing and coronary revascularization to highly selected patients and limiting coronary revascularization to patients with severe cardiac symptoms, we compared two time periods (1994-1995 and 2000-2001) with respect to cardiac work-up and cardiac morbidity and mortality. Our method involved a retrospective review of patients undergoing vascular procedures from 2000 to 2001 at a single institution. In group 1 (2000-2001), 139 operations were performed on 120 patients. In group 2 (1994-1995), 145 procedures were performed on 109 patients. Preoperative stress testing was reduced from 42 patients (29%) in group 2 to 20 patients (14%) in group 1 (P < 0.01), and preoperative coronary artery bypass grafting was reduced from six (4.1%) to two (1.4%) (P < 0.28), respectively. Coronary angiography was unchanged: 8 (5.8%) patients in group 1 versus 11 (7.9%) patients in group 2 (P = NS). Two (1.4%) patients underwent percutaneous transluminal coronary angioplasty in group 1 and group 2. Cardiac event rates were similar: seven (5%) patients in both groups. Cardiac death was not significantly different: two (1.4%) in group 1 versus one (0.7%) in group 2. Cardiac morbidity and mortality after major vascular surgery remain the same despite using a more selective cardiac stress protocol.

Effects of obesity surgery on non-insulin-dependent diabetes mellitus.

CONTEXT: Most individuals who have non-insulin-dependent diabetes mellitus are obese. The obese population has proved a frustrating entity regarding weight loss and diabetes control. Results of medical weight loss programs, medications, and behavior therapy have proved disappointing. HYPOTHESIS: Bariatric surgery is the most effective method of diabetes management and cure in the morbidly obese population. Surgical procedures to cause malabsorption provide a more dramatic effect on diabetes owing to the imparted bypass of the hormonally active foregut. DATA SOURCES: Pertinent journal articles spanning the last 40 years, as well as textbooks. CONCLUSIONS: Bariatric surgical procedures have proven a much more successful method of weight loss and diabetes control in the obese population than conservative methods. These surgical procedures have proven safe with reported mortality rates of 0% to 1.5%. Bariatric operations may be divided based on the method of weight loss and effect on diabetes. The first category is restrictive and includes vertical banded gastroplasty and adjustable silicone gastric banding. These operations improve diabetes by decreasing food intake and body weight with a slowing of gastric emptying. The second category not only contains restrictive components but also elements of malabsorption. This category includes the Roux-en-Y gastric bypass and biliary-pancreatic diversion, which bypass the foregut. Although all of the surgical procedures for obesity offer improved weight loss and diabetes control compared with conservative methods, the Roux-en-Y gastric bypass and biliary-pancreatic diversion offer superior weight loss and resolution of diabetes. The more dramatic effect seen in the surgical procedures to cause malabsorption is likely secondary to the bypass of the foregut resulting in increased weight loss and elevation of the enteroglucagon level.