Electroacupuncture alleviates intestinal inflammation via a distinct neuro-immune signal pathway in the treatment of postoperative ileus.

BACKGROUND: The induction of intestinal inflammation as a result of abdominal surgery is an essential factor in postoperative ileus (POI) development. Electroacupuncture (EA) at ST36 has been demonstrated to relieve intestinal inflammation and restore gastrointestinal dysmotility in POI. This study aims to elucidate the neuroimmune pathway involved in the anti-inflammatory properties of EA in POI. METHODS: After intestinal manipulation (IM) was performed to induce POI, intestinal inflammation and motility were assessed 24 h post-IM, by evaluating gastrointestinal transit (GIT), cytokines expression, and leukocyte infiltration. Experimental surgery, pharmacological intervention, and genetic knockout mice were used to elucidate the neuroimmune mechanisms of EA. RESULTS: EA at ST36 significantly improved GIT and reduced the expression of pro-inflammatory cytokines and leukocyte infiltration in the intestinal muscularis following IM in mice. The anti-inflammatory effectiveness of EA treatment was abolished by sub-diaphragmatic vagotomy, whereas splenectomy did not hinder the anti-inflammatory benefits of EA treatment. The hexamethonium chloride (HEX) administration contributes to a notable reduction in the EA capacity to suppress inflammation and enhance motility dysfunction, and EA is ineffective in α7 nicotinic acetylcholine receptor (α7nAChR) knockout mice. CONCLUSIONS: EA at ST36 prevents intestinal inflammation and dysmotility through a neural circuit that requires vagal innervation but is independent of the spleen. Further findings revealed that the process involves enteric neurons mediating the vagal signal and requires the presence of α7nAChR. These findings suggest that utilizing EA at ST36 may represent a possible therapeutic approach for POI and other immune-related gastrointestinal diseases.

Development of integrated smartphone/resistive biosensor for on-site rapid environmental monitoring of organophosphate pesticides in food and water.

Organophosphate (OP) pesticides remain a worldwide health concern due to their acute or chronic poisoning and widespread use in agriculture around the world. There is a need for robust and field-deployable tools for onsite detection of OP pesticides in food and water. Herein, we present an integrated smartphone/resistive biosensor for simple, rapid, reagentless, and sensitive monitoring of OP pesticides in food and environmental water. The biosensor leverages the hydrolytic activity of acetylcholinesterase (AChE) to its substrate, acetylcholine (ACh), and unique transport properties of polyaniline nanofibers (PAnNFs) of chitosan/AChE/PAnNF/carbon nanotube (CNT) nanocomposite film on a gold interdigitated electrode. The principle of the sensor relies on OP inhibiting AChE, thus, reducing the rate of ACh hydrolysis and consequently decreasing the rate of protons doping the PAnNFs. Such resulted decrease in conductance of PAnNF can be used to quantify OP pesticides in a sample. A mobile app for the biosensor was developed for analyzing measurement data and displaying and sharing testing results. Under optimal conditions, the biosensor demonstrated a wide linear range (1 ppt-100 ppb) with a low detection limit (0.304 ppt) and high reproducibility (RSD <5%) for Paraoxon-Methyl (PM), a model analyte. Furthermore, the biosensor was successfully applied for analyzing PM spiked food/water samples with an average recovery rate of 98.3% and provided comparable results with liquid chromatography-mass spectrometry. As such, the nanosensing platform provides a promising tool for onsite rapid and sensitive detection of OP pesticides in food and environmental water.

Genipin Attenuates Sepsis-Induced Splenocyte Apoptosis via the Inhibition of Endoplasmic Reticulum Stress.

Endoplasmic reticulum (ER) dysfunction is characterized by ER stress, which can be triggered by sepsis. Recent studies have reported that lessening ER stress is a promising therapeutic approach to improving the outcome of sepsis. Genipin is derived from gardenia fruit, which is a traditional Chinese medicinal herb for anti-inflammation. Here, mice were treated with genipin (2.5 mg/kg) intravenously to assess its biological effects and underlying mechanism against polymicrobial sepsis. Furthermore, the present study focused on detecting the levels of ER stress-related proteins, including protein kinase R-like ER kinase (PERK), glucose-regulated protein of 78 kDa (GRP78), phosphorylated-eukaryotic initiation factor 2α (p-eIF2α), and CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP). The results demonstrated that genipin significantly decreased the serum concentrations of tumor necrosis factor-α and interleukin-6, alleviated histopathological damage to the lungs, livers and spleens, and even improved the survival rates of septic mice. Moreover, sepsis significantly upregulated the protein expression levels of splenic GRP78, PERK, p-eIF2α and CHOP, but their levels were significantly suppressed by genipin. Furthermore, genipin also significantly downregulated cleaved caspase-3 expression levels and reduced sepsis-induced splenocyte apoptosis. In conclusion, genipin potentially improved the survival rate of sepsis and attenuated sepsis-induced organ injury and an excessive inflammatory response in mice. The effects of genipin against sepsis were potentially associated with decreased splenocyte apoptosis via the attenuation of sepsis-induced ER stress to further inhibit ER stress-induced apoptosis.

Improvement of the sepsis survival rate by adenosine 2a receptor antagonists depends on immune regulatory functions of regulatory T-cells.

Adenosine shows a significant immunosuppressive effect in sepsis via binding to the adenosine 2a receptor (A2aR). Both genetic deletion and pharmacological inhibition of the A2aR may improve survival in sepsis. However, available research on this protective mechanism is quite limited. We used an A2aR antagonist (ZM241385) to treat a cecal ligation and puncture model of normal mice or regulatory T-cell (Treg)-depletion mice and found that the protective effect of ZM241385 is dependent on Tregs. Mechanically, A2aR inactivation was associated with decreased frequencies and reduced function of Foxp3+ Tregs, as evidenced by Foxp3 and CTLA-4 expression and classical effector T-cell proliferative assays, suggesting Treg modulation is a potential protective mechanism against sepsis. Simultaneously, the function and quantity of abdominal neutrophils were improved with ZM241385 treatment. To see if a link exists between them, Tregs and neutrophils were co-cultured, and it was found that ZM241385 blocked the inhibitory effect of Tregs on neutrophils. According to our research, Tregs play a key role in how A2aR antagonists improve sepsis prognosis and bacterial clearance.

Insights into the interaction of CaCl2 and potato starch: Rheological, structural and gel properties.

High viscosity of starch greatly limit its application in some specific foods, in this work, a novel low-viscosity potato starch (PS) was developed via crosslinking between PS (3 %, w/v) and Ca2+ to investigate the effect of CaCl2 concentration (0.1-5 % CaCl2, w/v) on the rheological behaviors, structural and gel properties of PS. The results showed that peak viscosity (PV), trough viscosity (TV), final viscosity (FV), and breakdown viscosity (BD) of pasting curves of CaCl2-treated PS were significantly reduced compared with the native PS. The CaCl2 treatment also decreased the firmness of the PS gel and increased its pasting temperature (PT) and gelatinization enthalpy (∆H). Moreover, The CaCl2 treatment also led to more organized crystallites in the PS granules as affected by the slight increase in the ratio of 1044/1015 cm-1 in the FT-IR analysis, reduced the homogeneity of ordered structures inside granules as indicated by the increase in conclusion temperature (Tc)-onset temperature (To) in DSC analysis, and decreased relatively crystallinity revealed by XRD analysis. The findings of this study indicated CaCl2-treated PS could serve as food ingredients with reduced paste viscosity and regulated paste stability under shear during heating.

The α7 Nicotinic Acetylcholine Receptor Agonist GTS-21 Improves Bacterial Clearance via Regulation of Monocyte Recruitment and Activity in Polymicrobial Septic Peritonitis.

The cholinergic anti-inflammatory pathway has been identified as an effective pathway to modify inflammatory responses. Here, we verified that delayed administration with a selective α7nAChR agonist GTS-21 enables a more efficient elimination of the offending pathogens, diminished inflammatory response and organ injury, and improved survival rates in the polymicrobial septic peritonitis model. We illustrated that the improved bacterial clearance upon GTS-21 stimulation was accompanied by enhanced recruitment of monocytes into the peritoneal cavity and simultaneously increased phagocytic activity and iNOS expression of these recruited monocytes. Mechanically, splenectomy prior to administration of GTS-21 attenuated the recruitment of monocytes into the peritoneal cavity and abolished the protective benefits of GTS-21 treatment. Meanwhile, GTS-21 administration accelerates the deployment of splenic monocytes during septic peritonitis. Collectively, these data suggested that appropriate selective pharmacological α7nAChR activation promotes monocytes trafficking in a spleen-dependent manner and upregulates the antibacterial activity of recruited monocytes during septic peritonitis, which may be utilized as a promising therapeutic modality for patients suffering from septic peritonitis.

Nanocomplexes of curcumin and glycated bovine serum albumin: The formation mechanism and effect of glycation on their physicochemical properties.

Bovine serum albumin (BSA) and BSA-glucose conjugates (GBSAⅠ and GBSAⅠI) with different extent of glycation were complexed with curcumin (CUR). The formation mechanism of BSA/GBSA-CUR complexes and the effect of glycation on their physicochemical properties were investigated. Fluorescence quenching and FTIR analysis indicated that the BSA/GBSA-CUR nanocomplexes were formed mainly by hydrophobic interactions. XRD analysis demonstrated that CUR was present in an amorphous state in the nanocomplexes. BSA with a greater extent of glycation (BSA < GBSAⅠ

Inhibition of ultraviolet-induced sea cucumber (Stichopus japonicus) autolysis by maintaining coelomocyte intracellular calcium homeostasis.

Apoptosis plays a critical role in sea cucumber autolysis. To investigate the ultraviolet (UV)-induced apoptosis, sea cucumbers with and without injection of BAPTA-AM (cytosolic calcium chelator) were exposed to UV (15 W/m2) for 30 min. The results showed that UV irradiation caused several changes in sea cucumber coelomocytes, including calcium imbalance, abnormal morphology of endoplasmic reticulum, upregulation of pro-apoptotic proteins CRT, CHOP, and caspases 9 and 3, and downregulation of anti-apoptotic protein Bcl-2. A comparison between the two groups showed that injection of the calcium chelator into sea cucumbers helped maintain coelomocyte intracellular calcium homeostasis and suppressed other abnormal changes caused by ER stress, indicating apoptosis in sea cucumbers is mediated by calcium imbalance and follows the activation of the ER stress pathway. Therefore, this study broadens understanding of the apoptotic mechanism involved in sea cucumber autolysis, which is helpful in developing preservative agents for sea cucumbers.

Fabrication of pea protein-curcumin nanocomplexes via microfluidization for improved solubility, nano-dispersibility and heat stability of curcumin: Insight on interaction mechanisms.

Poor dispersibility of curcumin (cur) in aqueous medium and heat instability are common drawbacks preventing its efficiently practical use. Herein, the aim of this work was to reduce the size of cur crystals to the nanoscale through solid dispersion technique and subsequently stabilize them in an amorphous form. In this work, different ratios of pea protein (PP) to cur (6: 1, 12:1, 18:1 and 24:1, w/w) nano-supernatant (NS) in water were prepared via microfluidization. Results showed that particle size, Zeta potential (ZP) and cur concentration of cur in PP-cur NS in optimal conditions reached 357.45 nm, -33.43 mV and 81.68 mg/L, respectively. PP-cur NS showed excellent storage stability within one month and high heat stability of 52.32% at 90 °C after 180 min. Structural analysis including FT-IR, DSC and XRD indicated that cur entered into the hydrophobic pocket of PP by hydrophobic interactions and hydrogen bonds after microfluidization. This study indicated that PP exhibiting as an emulsifier and carrier might significantly reduce the surface tension of NS and in turns prolong their storability.

Upregulation of COL8A1 indicates poor prognosis across human cancer types and promotes the proliferation of gastric cancer cells.

Gastric cancer (GC) was one of the most common types of the digestive system. COL8A1 was reported to be associated with cancer progression. The present study showed COL8A1 was overexpressed and correlated to shorter overall survival (OS) time across human cancer types. Specially, our results showed COL8A1 was up-regulated in advanced stage GC compared to low stage GC samples. Higher expression of COL8A1 was significantly correlated to shorter OS time in patients with GC. Bioinformatics analysis revealed COL8A1 was involved in regulating cell proliferation and metastasis. Experimental validations of COL8A1 showed that silencing of COL8A1 could significantly suppressed cell proliferation, migration and invasion in GC. These results provided a potential target for the clinical prognosis and treatment of gastric cancer.

Rapid Pasteurization of Apple Juice Using a New Ultrasonic Reactor.

A new ultrasonic reactor was used to rapidly inactivate Escherichia coli and Staphylococcus aureus in apple juice. It was found that high pulp content made ultrasound less lethal to S. aureus, while it had no significant effect on E. coli. When the pulp free apple juice was ultrasonically processed, the 5-log reduction time was 35 s for E. coli at 60 °C and 30 s for S. aureus at 62 °C. Ultrasound treatment had no significant effect on antioxidant activity determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, but it significantly increased the total phenolic content. The treatment also resulted in more stable juice with higher uniformity. During 28 d of storage at 4 °C, the total plate count in apple juice ultrasonically treated at 60 °C for 35 s remained around 1.00 log CFU/mL, whereas it was nearly zero for a stronger ultrasound treatment at 62 °C for 30 s. These values were much lower than those in the untreated one, which increased from 3.65 log CFU/mL to 8.36 log CFU/mL during the storage. At the end of the storage, the control and thermally treated apple juice lost almost 70% of antioxidant activity, whereas the ultrasonically treated juice only lost 20-40%.

Development of high-fiber wheat bread using microfluidized corn bran.

Microfluidized corn bran is an excellent source of dietary fiber but has not been used to develop high-fiber bread. To develop such bread, it replaced 18, 20, and 22% of flour in the control white bread formula. At the standard water content, the amount of water required to develop a dough consistency of 500 Brabender Units in farinograph tests, the resulting bread had worse microstructure and textural properties, and much smaller loaf volume than the control bread. Instead of using existing physical, chemical and enzymatic methods to reduce the deteriorating effects of bran, we resolved the issue effectively by optimizing the water content in bread formulas. For the three levels of bran addition, when the water content was increased from its standard values of 38.3, 38.6, 38.8% to 40.8, 41.9, and 44.0%, respectively, the obtained loaves exhibited similar microstructure, specific loaf volume, and textural properties to the control bread.

Prediction of swelling behavior of crosslinked maize starch suspensions.

Rheological properties of starch are affected by swelling of the granules that is in turn controlled by the degree of crosslinking. A previously developed model for swelling of starch granules was extended to account for electrostatic interactions. Maize starch was crosslinked with sodium trimetaphosphate. Granule swelling of 8% suspension of crosslinked maize starch when subjected to heating to 70,75,80,85 and 90 °C was more pronounced at higher temperatures eventually approaching equilibrium with the swelling ratio decreasing with increase in extent of crosslink. The number of crosslinks in the starch network was inferred from equilibrium swelling and related to peak viscosity and zeta potential. Chemical potential profile as well as the temperature profile within the granule at different times were predicted which were then employed to evaluate the evolution of granule size. The proposed model is able to describe the effect of crosslinking on swelling behavior.

[Safety and efficacy of hand-assisted laparoscopic versus open distal gastrectomy for gastric cancer: A systematic review and meta-analysis].

OBJECTIVE: To systematically assess the safety and efficacy of hand-assisted laparoscopic distal gastrectomy (HALG) versus open distal gastrectomy (ODG) for gastric cancer. METHODS: Chinese or English literature regarding comparison of HALG and ODG were collected by searching in databases (such as PubMed, Cochrane Library, CNKI, Wanfang database) between January 1996 and September 2016. The data of operative time, incision length, blood loss, number of harvested lymph nodes, time to flatus, hospital stay, postoperative complication morbidity and long-term outcomes were compared between the two procedures. Then funnel plot was used to evaluate publication bias and sensitivity analysis was used to evaluate the stability of the results. All these data analyses were performed using the Meta for or Meta package of R version 3.3.1. RESULTS: A total of 7 studies with 835 patients (323 cases in HALG group and 512 cases in ODG group) were included. Compared with ODG, HALG had a longer operative time (WMD=28.93 minutes, 95%CI=9.59 to 48.28, Z=2.93, P=0.000), a shorter incision length (WMD=-10.31 cm, 95%CI=-14.01 to -6.62, Z=-5.47, P=0.000), less blood loss (WMD=-140.08 ml, 95%CI=-215.07 to -65.09, Z=-3.66, P=0.000), faster gastrointestinal recovery (WMD=-1.23 days, 95%CI=-1.89 to -0.56, Z=-3.62, P=0.000), shorter postoperative hospital stay (WMD=-3.24 days, 95%CI=-5.47 to -1.02, Z=-2.85, P=0.000). In subgroup analysis, 3 studies published before 2013 vs. 4 studies published afterwards, the number of harvested lymph nodes (WMD=-0.78, 95%CI=-2.05 to 0.50, Z=-1.19, P=0.235) and postoperative complication morbidity (RR=1.02, 95%CI=0.43 to 2.44, Z=0.05, P=0.961) did not differ significantly between two groups. Compared with ODG, the RR(95%CI) of ileus of HALG was 0.43 (0.07 to 2.82), but the difference was not statistically significant (P=0.383). One study reported the 5-year overall survival rates of HALG and ODG were 81.0% vs 67.5%, and the tumor recurrence rates were 7.1% vs 22%, respectively, but the differences were not statistically significant(all P>0.05). Sensitivity analysis showed that the above results were stable. The funnel plots of the lymph nodes and postoperative complication morbidity did not present significant publication bias. CONCLUSIONS: HALG has the advantages of minimal invasiveness such as shorter incision length and quicker recovery. Furthermore, the short-term efficacy of HALG is similar to conventional open surgery. However, the long-term efficacy is lack of support from multicenter long-term follow-up results.

Evaluation of Tc-99m-3PRGD2 Integrin Receptor Imaging in the Differential Diagnosis of Breast Lesions and Comparison With Mammography.

PURPOSE: The aims of this study were to evaluate and compare efficacies of Tc-99m-3PRGD2 integrin receptor imaging under variety of conditions for the diagnosis of breast lesions, in addition to comparison with mammography. MATERIALS AND METHODS: Seventy-two female patients with established breast lesions were recruited. All patients were examined by Tc-99m-3PRGD2 integrin receptor imaging and mammography. Whole-body scan and SPECT/CT were acquired at dual time points of 2 and 4 h after injection using standard protocol. The processed images were evaluated by visual and semi-quantitative analysis. Mammography was performed using up and down and internal and external oblique views. The gold standard of diagnosis was based on histopathological findings. RESULTS: Sensitivity greater than 85.0% and accuracy greater than 80.0% were observed under any technical method. For dense mammary gland, the sensitivity, specificity, and accuracy of Tc-99m-3PRGD2 SPECT/CT 4-h imaging and mammography were 95.2, 75.0, and 90.7%, and 71.4, 58.3, and 68.5% respectively. Combined two methods' sensitivity, specificity, and accuracy for detection of breast cancer can reach 98.3, 86.7, and 96.0%. CONCLUSIONS: Tc-99m-3PRGD2-based molecular imaging is a sensitive method for the differential diagnosis of breast lesions. Particularly, Tc-99m-3PRGD2-SPECT/CT has better diagnostic value in dense mammary gland as compared with mammography. Combining two methods can significantly improve the diagnostic efficiency.

A Novel Copolymer-Based Functional SPECT/MR Imaging Agent for Asialoglycoprotein Receptor Targeting.

The aim of this study is to develop a copolymer-based single-photon emission computed tomography/magnetic resonance (SPECT/MR) dual-modality imaging agent that can be labeled with both technetium-99m (99mTc) and gadolinium (Gd) and target asialoglycoprotein receptor (ASGPR) via galactose. Monomers of N-p-vinylbenzyl-6-(2-(4-dimethylamino)benzaldehydehydrazono) nicotinate (VNI) for labeling of 99mTc, 5,8-bis(carboxymethyl)-3-oxo-11-(2-oxo-2-((4-vinylbenzyl)amino)ethyl)-1-(4-vinylphenzyl)-2,5,8,11-tetraazatridecan-13-oic acid (V2DTPA) for labeling of Gd, and vinylbenzyl-O-ß-d-galactopyranosyl-d-gluconamide (VLA) for targeting ASGPR were synthesized, respectively. Then the copolymer P(VLA-co-VNI-co-V2DTPA) (pVLND2) was synthesized and characterized by gel permeation chromatography, dynamic light scattering, and high-performance liquid chromatography analysis. After labeling with 99mTc and Gd simultaneously, the radiochemical purity, toxicity, relaxivity (r1), and in vivo SPECT/MR imaging in mice were evaluated. Single-photon emission computed tomography/magnetic resonance imaging and biodistribution results showed that pVLND2 could target ASGPR well. The significantly improved signal to noise ratio was observed in mice liver during MR imaging. All the results suggest that this novel kind of copolymer has the potential to be further developed as a functional SPECT/MR imaging agent.

Simultaneous SPECT imaging of multi-targets to assist in identifying hepatic lesions.

Molecular imaging technique is an attractive tool to detect liver disease at early stage. This study aims to develop a simultaneous dual-isotope single photon emission computed tomography (SPECT)/CT imaging method to assist diagnosis of hepatic tumor and liver fibrosis. Animal models of liver fibrosis and orthotopic human hepatocellular carcinoma (HCC) were established. The tracers of (131)I-NGA and (99m)Tc-3P-RGD2 were selected to target asialoglycoprotein receptor (ASGPR) on the hepatocytes and integrin αvß3 receptor in tumor or fibrotic liver, respectively. SPECT imaging and biodistribution study were carried out to verify the feasibility and superiority. As expected, (99m)Tc-3P-RGD2 had the ability to evaluate liver fibrosis and detect tumor lesions. (131)I-NGA showed that it was effective in assessing the anatomy and function of the liver. In synchronized dual-isotope SPECT/CT imaging, clear fusion images can be got within 30 minutes for diagnosing liver fibrosis and liver cancer. This new developed imaging approach enables the acquisition of different physiological information for diagnosing liver fibrosis, liver cancer and evaluating residual functional liver volume simultaneously. So synchronized dual-isotope SPECT/CT imaging with (99m)Tc-3P-RGD2 and (131)I-NGA is an effective approach to detect liver disease, especially liver fibrosis and liver cancer.

Explicit numerical solutions of a microbial survival model under nonisothermal conditions.

Differential equations used to describe the original and modified Geeraerd models were, respectively, simplified into an explicit equation in which the integration of the specific inactivation rate with respect to time was numerically approximated using the Simpson's rule. The explicit numerical solutions were then used to simulate microbial survival curves and fit nonisothermal survival data for identifying model parameters in Microsoft Excel. The results showed that the explicit numerical solutions provided an easy way to accurately simulate microbial survival and estimate model parameters from nonisothermal survival data using the Geeraerd models.

Clinical features of and risk factors for major depression with history of postpartum episodes in Han Chinese women: A retrospective study.

BACKGROUND: We sought to investigate the clinical features of and risk factors for recurrent major depression (MD) with history of postpartum episodes (PPD) in Han Chinese women and the differences between first-onset postpartum MD (MD that has its first lifetime depressive episode in the postpartum period) and first-onset non-postpartum MD (MD with history of PPD and has its first lifetime depressive episode in a period other than postpartum). METHODS: Data were derived from the China, Oxford and Virginia Commonwealth University Experimental Research on Genetic Epidemiology (CONVERGE) study (N=6017 cases) and analyzed in two steps. We first examined the clinical features of and risk factors for MD patients with (N=981) or without (N=4410) a history of PPD. We then compared the differences between first-onset postpartum MD (N=583) and first-onset non-postpartum MD (N=398) in those with a history of PPD. Linear, logistic and multinomial logistic models were employed to measure the associations. RESULTS: A history of PPD was associated with more guilt feelings, greater psychiatric comorbidity, higher neuroticism, earlier onset and more chronicity (OR 0.2-2.8). Severe premenstrual symptoms (PMS) and more childbirths increased the risk of PPD, as did a family history of MD, childhood sexual abuse, stressful life events and lack of social support (OR 1.1-1.3). In the MD with history of PPD subsample, first-onset postpartum MD was associated with fewer recurrent major depressive episodes, less psychiatric comorbidity, lower neuroticism, less severe PMS and fewer disagreements with their husbands (OR 0.5-0.8), but more childbirths (OR 1.2). LIMITATIONS: Data were obtained retrospectively through interview and recall bias may have affected the results. CONCLUSIONS: MD with history of PPD in Han Chinese women is typically chronic and severe, with particular risk factors including severe PMS and more childbirths. First-onset postpartum MD and first-onset non-postpartum MD can be partly differentiated by their clinical features and risk factors, but are not clearly distinctive.

Numerical solution of a microbial growth model applied to dynamic environments.

The Baranyi and Roberts model is one of the most frequently used microbial growth models. It has been successfully applied to numerous studies of various microorganisms in different food products. Under dynamic conditions, the model is implicitly formulated as a set of two coupled differential equations which could be numerically solved using the Runge-Kutta method. In this study, a simplified numerical solution of the coupled differential equations was derived and used to simulate microbial growth under dynamic conditions in Microsoft Excel. As expected, the results obtained were the same as those from solving the coupled differential equations using a MATLAB Solver. In addition, model parameters were accurately identified by fitting the numerical solution to simulated growth curves under dynamic (time-varying) temperature conditions using the Microsoft Excel Solver.