Cell viability prediction and optimization in extrusion-based bioprinting via neural network-based Bayesian optimization models.

The fields of regenerative medicine and cancer modeling have witnessed tremendous growth in the application of 3D bioprinting. Maintaining high cell viability throughout the bioprinting process is crucial for the success of this technology, as it directly affects the accuracy of the 3D bioprinted models, the validity of experimental results, and the discovery of new therapeutic approaches. Therefore, optimizing bioprinting conditions, which include numerous variables influencing cell viability during and after the procedure, is of utmost importance to achieve desirable results. So far, these optimizations have been accomplished primarily through trial and error and repeating multiple time-consuming and costly experiments. To address this challenge, we initiated the process by creating a dataset of these parameters for gelatin and alginate-based bioinks and the corresponding cell viability by integrating data obtained in our laboratory and those derived from the literature. Then, we developed machine learning models to predict cell viability based on different bioprinting variables. The trained neural network yielded regressionR2value of 0.71 and classification accuracy of 0.86. Compared to models that have been developed so far, the performance of our models is superior and shows great prediction results. The study further introduces a novel optimization strategy that employs the Bayesian optimization model in combination with the developed regression neural network to determine the optimal combination of the selected bioprinting parameters to maximize cell viability and eliminate trial-and-error experiments. Finally, we experimentally validated the optimization model's performance.

[Indications for antireflux surgery: a clinical experience and review of the literature]. / Indicaciones de cirugía antirreflujo. Buenos y malos candidatos para la cirugía? Revisión bibliográfica y experiencia personal.

Antireflux laparoscopic surgery has excellent results in terms of improvement of symptoms, esophagitis, gastroesophageal sphincter competence and abnormal acid reflux. Indications for surgery are well established, however some of these are controversial. This is a review of the present indications for surgery in gastroesophageal reflux. The surgical indication should be the result of a complex clinical and laboratory work up. Patients with a clear cut surgical indication should be differentiated from those with doubtful indications, that require further analysis and those that are bad candidates for surgery. Young patients with macroscopic esophagitis, an incompetent sphincter, abnormal acid reflux test, that have a partial or negative response to treatment with proton pump inhibitors are those with the best surgical results. Bad candidates are patients with a psychiatric background, with atypical symptoms and those with a normal acid reflux test. In our experience with 935 patients, only 23% had a surgical indication.

Evolution of type 2 diabetes mellitus in non morbid obese gastrectomized patients with Roux en-Y reconstruction: retrospective study.

OBJECTIVE: Bariatric surgery in morbidly obese patients with type 2 diabetes results systematically in adequate glycemic control, normalization of insulinemia, and a decrease in glycosylated hemoglobin, effects that appear early after surgery in nearly 80 to 90% of them. Possible reasons that have been discussed are a decrease in caloric consumption, weight loss, and hormonal changes at the gastrointestinal level, which could have a positive effect on glucose metabolism. Various authors have proposed the possibility of passing on this indication to diabetic patients who are overweight or are mildly obese. The purpose of this retrospective investigation was to determine the effect of total or subtotal gastrectomy with Roux-en-Y reconstruction on the metabolic control of patients with type 2 diabetes with a body mass index (BMI) < 35, operated on for reasons other than obesity. METHODS: From January 1999 to December 2007, a total of 23 diabetic patients who underwent total or subtotal gastrectomy with a gastrojejunal or esphagojejunal anastomosis with Roux-en-Y reconstruction of 60 to 70 cm length were included in this investigation. RESULTS: The group consisted of 23 patients (14 men, 9 women, average age 62.9 +/- 7.9 years, average BMI 29.1 +/- 5.1). The principal reason for gastrectomy in these patients was gastric cancer in 19 patients (82.6%). The surgical procedure was total gastrectomy in 17 cases (73.9%) and subtotal gastrectomy in 6 cases (26.1%). Postoperative follow-up was 22 months. Before surgery the mean blood glucose level was 151.4 mg/dl. Late after surgery, 15 patients (65.2%) had a fasting blood glucose <126 mg/dl and are not using medication (remission), 7 (30.4%) patients have better metabolic control with a normal blood glucose but are still taking medication (improvement), and just 1 (4.3%) patient has an altered blood glucose and uses insulin (no change). CONCLUSIONS: Gastrectomy and short Roux-en-Y limb reconstruction in type 2 diabetes patients with BMI < 35, with the patients submitted to surgery mainly for gastric cancer, correlates with remission of diabetes in 65% and improvement in 30.4%.

Biosynthesis of poly-beta-hydroxyalkanoate by Brevundimonas vesicularis LMG P-23615 and Sphingopyxis macrogoltabida LMG 17324 using acid-hydrolyzed sawdust as carbon source.

Poly-beta-hydroxyalkanoate (PHA) is a biodegradable polymer accumulated in intracellular granules by different bacterial species. Its physical and chemical properties are similar to those of petroleum-derived plastics. Material generated by the acid hydrolysis of wood was evaluated for use in the bacterial synthesis of PHA. Acid-hydrolyzed sawdust was prepared and adjusted to pH 7. Mineral salts with carbon:nitrogen (C:N) proportions of 100:1, 100:3.5, 100:10, 100:30, or 100:50 and trace elements were added and these solutions were inoculated with a bacterial strain Brevundimonas vesicularis LMG P-23615 or Sphingopyxis macrogoltabida LMG 17324. The percentage of cells accumulating PHA was evaluated by flow cytometry. The hydrolyzed sawdust composition was analyzed by gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). The organic material (601.5 mg l(-1)) contained 112.5 mg l(-1) sugars. Over 96% of these sugars were consumed and more than 90% of the bacterial cells accumulated PHA. The 100:3.5 C:N proportion was optimal for growth and PHA synthesis, with yields ranging from 64% to 72% of the dry cell weight. The results suggest that acid-hydrolyzed sawdust can be used by bacteria as a carbon source for growth and PHA production. This forestry by sub-product offers a low-cost alternative for obtaining biodegradable plastics (e.g., PHA) synthesized by bacteria.