Bolus Feeding Research Articles

Continuous versus bolus intragastric tube feeding for preterm and low birth weight infants with gastro-oesophageal reflux disease.

Gastro-oesophageal reflux disease is a particularly common condition in preterm and low birth weight infants. These infants are also more likely to have excessive regurgitation, as they do not have a fully developed antireflux mechanism. Preterm and low birth weight infants who are unable to suck oral feeds are required to be fed via an intragastric tube for varying lengths of time. Intragastric tube feeding can be delivered by the intermittent bolus or continuous feeding method. Use of continuous or intermittent bolus intragastric feeding may have a positive or negative effect on the incidence or severity of gastro-oesophageal reflux disease. To determine whether continuous or intermittent bolus intragastric tube feeding reduces the number of episodes and the duration of gastro-oesophageal reflux disease (GORD) in preterm and low birth weight infants.We intended to perform subgroup analyses for gestational age; birth weight; age in days from birth at full enteral feeding via intragastric tube (breast vs bottle); frequency of intermittent bolus feed; and type of medication for treatment of GORD (only if medication prescribed and given similarly to both intervention groups). We used the standard search strategy of the Cochrane Neonatal Group as described in The Cochrane Library (www.thecochranelibrary.com) to search for randomised controlled trials (RCTs) in the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 9), MEDLINE (1966 to September 2013), EMBASE (1980 to September 2013) and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to September 2013). We also searched previous reviews, including cross-references, abstracts and conference and symposia proceedings of the Perinatal Society of Australia and New Zealand and the Pediatric Academic Societies (American Pediatric Society/Society for Pediatric Research and European Society for Paediatric Research) from 1990 to 2012. Published and unpublished RCTs and quasi-RCTs were eligible for inclusion in this review, as were cluster-randomised and cross-over randomised trials that compared the effects of continuous versus intermittent bolus intragastric tube feeding on gastro-oesophageal reflux disease in preterm and low birth weight infants. Two review authors independently assessed study eligibility and quality. We found no trials that met the inclusion criteria for this review. We did not identify any randomised trials that evaluated the effects of continuous versus intermittent bolus intragastric tube feeding on gastro-oesophageal reflux disease in preterm and low birth weight infants. Well-designed and adequately powered trials are needed.

Patients living with home enteral tube feeding: Side effects, health-related quality of life and nutritional care

The aim of the study was to examine patients’ perceptions of side effects, health-related quality of life (HRQL), general health, and nutritional care among patients receiving home enteral tube feeding (HETF) at two occasions after discharge from hospital. Three questionnaires, one study-specific, the Short Form 12 (SF-12) and the Health Index (HI), were sent to patients with HETF (n=62) twice, two weeks after discharge from hospital and two months later. Forty patients responded two weeks after discharge and out of these 29 patients also responded after two months. Data were collected in central Sweden from March 2006 to January 2010. Side effects were common at both points of data collection (70% of the patients after two weeks and 72% after two month). Patients using bolus feeding reported significantly fewer side effects than patients using intermittent feeding. HRQL and HI scores for the total group were low at both points of data collection. The bolus feeding group reported significantly higher physical HRQL and emotional HI than the intermittent feeding group did. Most patients were satisfied with the information and support they received from the health care team. This study has revealed that patients treated with HETF experienced side effects limiting their daily life to a great extent. Differences in HRQL related to feeding methods were found. Individualized support and regular controls are needed in order to meet patient needs. Bolus feeding may be a suitable feeding method to improve well-being.

Nutrition Support for Pediatric Short Bowel Syndrome

Short bowel syndrome (SBS) develops in infants and children with inadequate small intestine for digestion and absorption of enteral nutrients for normal growth and development. This can lead to malabsorption of macronutrients or micronutrients, electrolyte imbalance, dehydration, malnutrition, and growth failure. The goals of nutrition support in pediatric SBS are to promote intestinal adaptation, avoid complications associated with intestinal resection and parenteral nutrition (PN), and, ultimately, maintain normal growth. In the initial phase of SBS, PN support is important in order to meet energy requirements and for avoidance of electrolyte imbalance or dehydration. Enteral nutrition should be initiated as soon as possible after bowel resection in order to promote intestinal adaptation. In order to stimulate oral motor activity and to avoid feeding aversion behavior, tolerable volumes of bottle-feeding or solid food should be accepted. In addition, feeding volume might be gradually increased in small amounts with monitoring of stool quantity and consistency. Because not all enterally administered calories are absorbed, PN should not be decreased isocalorically against enteral nutrition. In order to enhance bowel adaptation by maximizing nutrient delivery, it is necessary to determine the potential advantages of administration mode, continuous vs. bolus feeding, and what formula should be considered, polymeric vs. monomeric or oligomeric formula. Optimal enteral feeding regimen for pediatric SBS is still being debated, how to feed or what to feed, therefore, nutritional management of SBS should be adjusted according to the patient’s medical condition.

Bolus vs. continuous feeding: effects on splanchnic and cerebral tissue oxygenation in healthy preterm infants

Intermittent and continuous tube feeding modes are commonly used to feed preterm infants. However, there is no clear evidence regarding which method is better tolerated. We investigated the differences between bolus and continuous feeding in terms of cerebral and splanchnic oxygenation in healthy preterm infants. Thirty preterm infants underwent a simultaneous 6-h near-infrared-spectroscopy monitoring of cerebral and splanchnic oxygenation, during which they were fed twice through an orogastric tube: one meal was given as a 10-min bolus, and the other was given continuously over a period of 3 h. Oxygenation trends over time were evaluated and compared between bolus and continuous feeding modes. Cerebral oxygenation did not change over time and did not differ between the two feeding techniques. Splanchnic oxygenation changed significantly over time and differed between the two feeding techniques, with a significant increase after bolus feeding and a remarkable reduction during continuous feeding. Bolus and continuous feeding modes influence splanchnic oxygenation in healthy preterm infants differently. Further studies are needed to investigate possible underlying mechanisms and potential effects on feeding tolerance.

Intermittent bolus feeding enhances vital organs growth compared with continuous feeding in neonates (258.7)

Orogastric tube feeding provides enteral nutrition to critically ill neonates unable to ingest normally, and can be administered by intermittent bolus (INT) or continuous (CON) infusion. Recently, we showed that INT compared to CON feeding enhances lean tissue accretion by increasing muscle protein synthesis in neonates. The aim of this study was to determine if these feeding modalities affect vital organ growth. Neonatal pigs (n=6, 6‐d‐old) were fed the same diet in equivalent amounts continuously or intermittently (meal every 4h) for 21d. Arterial branched‐chain amino acid and insulin concentrations measured on the last day of feeding were greater for INT after the meal than for CON pigs (P<0.05). Protein synthesis increased by 14% in jejunum, 48% in ileum, and 22% in liver of INT compared to CON pigs (P<0.05), while for the kidneys the increase was only modest. Jejunum, ileum, liver and kidneys were 41, 36, 73 and 55% heavier for pigs in the INT as compared to the CON group (P<0.05). Phosphorylation of ribosomal protein S6 kinase were higher in ileum and liver in INT compared to CON fed pigs indicating increased translation initiation (P<0.05). The proportion of rpS8 mRNA associated with polysomes in liver was greater in the INT compared to CON fed group (P<0.05). These results suggest that intermittent feeding enhances vital organ growth by up‐regulating protein synthesis.Grant Funding Source: Supported by NIH AR444474 and USDA/ARS 6250‐51000‐055

Forage fiber effects on particle size reduction, ruminal stratification, and selective retention in heifers fed highly digestible grass/clover silages1

The objective of this study was to investigate the effect of NDF content in highly digestible grass/clover silage on particle size reduction, ruminal stratification, and selective retention in dairy heifers. The reduction in particle size from feed to feces was evaluated and related to feed intake, chewing activity, and apparent digestibility. Four grass/clover harvests (Mixtures of Lolium perenne, Trifolium pratense, and Trifolium repens) were performed from early May to late August at different maturities, at different regrowth stages, and with different clover proportions, resulting in silages with NDF contents of 312, 360, 371, and 446 g/kg DM, respectively, and decreasing NDF digestibility with greater NDF content. Four rumen-fistulated dairy heifers were fed silage at 90% of ad libitum level as the only feed source in a 4 × 4 Latin square design. Silage, ingested feed boluses, medial and ventral ruminal digesta, and feces samples were washed with neutral detergent in nylon bags of 10-μm pore size, freeze dried, and divided into small (<0.212 mm), medium (0.212 to 1 mm), and large : LP; >1 mm) particles by dry-sieving. Chewing activity, rumen pool size, and apparent digestibility were measured. Intake of NDF increased linearly from 2.3 to 2.8 kg/d with greater NDF content of forages (P = 0.01), but silages were exposed to similar eating time (P = 0.55) and rumination time per kg NDF (P = 0.35). No linear effect of NDF content was found on proportion of LP in ingested feed boluses (P = 0.31), medial rumen digesta (P = 0.95), ventral rumen digesta (P = 0.84), and feces (P = 0.09). Greater proportions of DM (P < 0.001) and particulate DM (P = 0.008) were found in medial ruminal digesta compared with ventral rumen, and differences in DM proportion increased with greater NDF content (P = 0.02). Particle size distributions were similar for digesta from the medial and ventral rumen regardless of NDF content of the silages (P > 0.13). The LP proportion was >30% of particles in the ventral and medial rumen, whereas in the feces, the LP proportion was <2%. Particle size stratification of the rumen was undetectable regardless of NDF content of the silages, stressing that the retention mechanism of large undigested particles lies elsewhere than with particle entrapment in the rumen mat. In this study, forage particle breakdown, ruminal stratification, and retention of particles in the rumen were not affected by NDF content of highly digestible grass/clover silages.

Glycaemic control in insulin requiring diabetes patients receiving exclusive enteral tube feeding in an acute hospital setting

AimsOptimising glycaemic control for insulin requiring individuals during enteral feeding is important but difficult. We compare 3 insulin regimens with the aim of improving glucose control and reducing hypoglycaemia. MethodsComparison of 3 insulin/feed regimens: (1) A 20h feed using a 30:70 premixed insulin (2) Three bolus (4h) feeds combined with short acting analogue insulin and a basal long acting insulin. (3) A 24h feed combined with a long acting analogue insulin. The study combined a retrospective analysis of regimen (1) with consecutive prospective analyses of (2) and (3). ResultsGlucose concentrations were suboptimal with higher values during the feeds (12.6mmol/L±4.4 vs 10.3±4.1 p<0.001). Although there was no overall difference in glucose control between groups there was a reduction in hypoglycaemia during the feed in the bolus group (no hypoglycaemia during intermittent feeds p<0.001). ConclusionsGlucose concentrations were relatively high overall. Short bolus feeding appears to reduce the frequency of hypoglycaemia. This is of clinical significance for this patient group.

Optimized fermentation conditions for improved antibody yield in hybridoma cells

Background Traditionally antibody producing cells like hybridoma cells sank into oblivion since other suspension cell lines have captured the biopharmaceutical production market. However, they are still of particular interest in academic and industrial diagnostic research. Hence, fast and sufficient antibody production is needed as proof of concept, for toxicology and in vivo studies. Although, hybridoma cultivation in fetal bovine serum (FBS) containing animal derived ingredients, like contaminating IgG, is undesirable and leads to difficulties in purification. When reducing the serum to a minimum other key components of the FBS have to be replaced. Therefore, human insulinlike growth factor (IGF) [1] and the surfactant Pluronic F68 were supplemented to improve overall cell performance and to reduce shear stress during shaking respectively employing Design of Experiment (DoE)[2]. Compared to the original basal medium an improvement in cell growth, viability and antibody titer was achieved. These optimized inoculum conditions were used for subsequent bioreactor fermentations. Furthermore, these conditions were used in order to test feeding strategies. For this purpose a fed-batch process with a double bolus feed was simulated in shake flasks with two different glucose feeding strategies with and without Hyclone Cell Boost 6 (CB6). Finally, the result from shake flasks could be verified and improved antibody yield was achieved in a controlled 2L fed-batch process.

Continuous milk feeding versus intermittent bolus feeding in preterm infants

We aimed to assess the current knowledge on continuous versus intermittent bolus feeding in preterm infants. We found that existing evidence does not support the firm recommendation of one strategy among the many alternatives. However, although many areas remain to be investigated, it is probable that continuous feeding might be advantageous compared to intermittent feeding in favoring the faster establishment of full enteral feeding, and decreasing the risk of hypoxic–ischemic gut damage in preterm neonates in critical condition, especially SGA infants, by limiting their gastrointestinal oxygen requirement.

Leucine pulses enhance skeletal muscle protein synthesis during continuous feeding in neonatal pigs

Infants unable to maintain oral feeding can be nourished by orogastric tube. We have shown that orogastric continuous feeding restricts muscle protein synthesis compared with intermittent bolus feeding in neonatal pigs. To determine whether leucine infusion can be used to enhance protein synthesis during continuous feeding, neonatal piglets received the same amount of formula enterally by orogastric tube for 25.25 h continuously (CON) with or without LEU or intermittently by bolus every 4 h (BOL). For the CON+LEU group, leucine pulses were administered parenterally (800 μmol·kg(-1)·h(-1)) every 4 h. Insulin and glucose concentrations increased after the BOL meal and were unchanged in groups fed continuously. LEU infusion during CON feeding increased plasma leucine after the leucine pulse and decreased essential amino acids compared with CON feeding. Protein synthesis in longissimus dorsi (LD), gastrocnemius, and soleus muscles, but not liver or heart, were greater in CON+LEU and BOL than in the CON group. BOL feeding increased protein synthesis in the small intestine. Muscle S6K1 and 4E-BP1 phosphorylation and active eIF4E·eIF4G complex formation were higher in CON+LEU and BOL than in CON but AMPKα, eIF2α, and eEF2 phosphorylation were unchanged. LC3-II-to-total LC3 ratio was lower in CON+LEU and BOL than in CON, but there were no differences in atrogin-1 and MuRF-1 abundance and FoxO3 phosphorylation. In conclusion, administration of leucine pulses during continuous orogastric feeding in neonates increases muscle protein synthesis by stimulating translation initiation and may reduce protein degradation via the autophagy-lysosome, but not the ubiquitin-proteasome pathway.

Viscera and muscle protein synthesis in neonatal pigs is increased more by intermittent bolus than by continuous feeding

Continuous and intermittent bolus orogastric feedings are strategies used in infants unable to tolerate normal feeds. To determine the effects of feeding modality on protein synthesis in different tissues, neonatal pigs received a balanced formula by orogastric tube as an intermittent bolus feed every 4 h or as a continuous infusion, or were fasted overnight. As compared with fasting, protein synthesis in gastrocnemius, masseter, and soleus muscles; left ventricle; liver; pancreas; jejunum; and kidney increased in bolus- and continuously fed pigs, but the greatest increase occurred after a bolus meal. Tuberous sclerosis complex (TSC2), the proline-rich AKT substrate of 40 kDa (PRAS40), eukaryotic initiation factor (eIF) 4E binding protein (4EBP1), and ribosomal protein S6 kinase 1 (S6K1) phosphorylation in all tissues, and the proportion of ribosomal protein S4 in liver polysomes were enhanced 90 min following the bolus meal but not immediately before the meal or during continuous feeding. Eukaryotic elongation factor 2 (eEF2) and eIF2α phosphorylation were unaffected by feeding. These results suggest that intermittent bolus feeding increases protein synthesis in muscles of different fiber types and visceral tissues to a greater extent than continuous feeding by stimulating translation initiation.

Near‐Infrared Spectroscopy Measurements of Splanchnic Tissue Oxygenation During Continuous Versus Intermittent Feeding Method in Preterm Infants

The aim of the present study was to compare the effects of continuous and intermittent bolus milk feeding on splanchnic regional oxygenation (rSO₂S) in small-for-gestational age (SGA) and appropriate-for-gestational age (AGA) preterm infants. Infants with gestational age <32 weeks were prospectively studied by near-infrared spectroscopy. Each infant was given a milk bolus in ~10 minutes (intermittent feeding) followed after 3 hours by a 3-hour continuous feeding. rO₂S and splanchnic fractional oxygen extraction ratio (FOES [S = splanchnic]) were recorded 30 minutes before (T₀) and 30 minutes after the beginning of bolus feeding (T₁), 30 minutes before (T₂), at the end (T₃), and 30 minutes after the continuous feeding period (T₄). rSO2S increased at T₁ in both AGA and SGA groups, whereas FOES did not vary during the study period. Moreover, we found that rSO2S was higher and FOES was lower at T₁ and T₃ in the AGA than in the SGA group. Bolus milk feeding increases splanchnic oxygenation in both AGA and SGA infants, whereas continuous feeding does not. Splanchnic oxygenation is higher in AGA than in SGA infants both during bolus and continuous feeding. Continuous enteral feeding could help to limit the risk of hypoxic-ischemic gut damage in preterm infants in critical condition, especially in AGA infants.

Refining dietary protein recommendations for the athlete

Refining dietary protein recommendations for the athlete

Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis

Quantity and timing of protein ingestion are major factors regulating myofibrillar protein synthesis (MPS). However, the effect of specific ingestion patterns on MPS throughout a 12 h period is unknown. We determined how different distributions of protein feeding during 12 h recovery after resistance exercise affects anabolic responses in skeletal muscle. Twenty-four healthy trained males were assigned to three groups (n = 8/group) and undertook a bout of resistance exercise followed by ingestion of 80 g of whey protein throughout 12 h recovery in one of the following protocols: 8 × 10 g every 1.5 h (PULSE); 4 × 20 g every 3 h (intermediate: INT); or 2 × 40 g every 6 h (BOLUS). Muscle biopsies were obtained at rest and after 1, 4, 6, 7 and 12 h post exercise. Resting and post-exercise MPS (l-[ring-(13)C6] phenylalanine), and muscle mRNA abundance and cell signalling were assessed. All ingestion protocols increased MPS above rest throughout 1-12 h recovery (88-148%, P < 0.02), but INT elicited greater MPS than PULSE and BOLUS (31-48%, P < 0.02). In general signalling showed a BOLUS>INT>PULSE hierarchy in magnitude of phosphorylation. MuRF-1 and SLC38A2 mRNA were differentially expressed with BOLUS. In conclusion, 20 g of whey protein consumed every 3 h was superior to either PULSE or BOLUS feeding patterns for stimulating MPS throughout the day. This study provides novel information on the effect of modulating the distribution of protein intake on anabolic responses in skeletal muscle and has the potential to maximize outcomes of resistance training for attaining peak muscle mass.

The effects of bolus versus pulse feeding strategies on muscle anabolism in older men

A topical advancement in understanding the control of muscle protein synthesis (MPS) was the discovery of a “Muscle‐Full” phenomenon, whereby feeding stimulates only transient increases in MPS, which return to postabsorptive values despite sustained availability of plasma and muscle essential amino acids (EAA) including leucine. Herein, we have explored this phenomenon in relation to aging by measuring MPS (13C6‐phenylalanine bound muscle) over a 6 h period (2 h fasted ‐4 h fed) using two distinct feeding regimens: 16 older men received either a single 15g mixed EAA feed (N=8, 70±2 y; ‘BOLUS’) or the same dose in 4 × 3.75g fractions at 45 min intervals (N=8, 70±3 y; ‘PULSE’). While MPS was unchanged in either group 0–90 min after EAA ingestion, it was elevated 91–180 min, irrespective of feeding strategy (BOLUS: 0.049 to 0.082 vs. PULSE: 0.046 to 0.071%.h−1, P&lt;0.05 2‐way RM ANOVA). In contrast, while MPS returned to baseline rates in BOLUS between 181–240 min (to 0.052%.h−1) this was not the case in PULSE (0.070%.h−1, P&lt;0.05). Despite these temporal differences equal total MPS responses to feeding regimens were revealed by area under the curve analysis (0.27% vs. 0.24% in 4 h, P&gt;;0.05). While equal total MPS between regimens suggests a dose, not time‐dependent mechanism regulates the muscle‐full state in older men, greater sustainment of the anabolic response over longer durations with PULSE feeding regimens may transpire.

Intermittent Bolus Feeding Enhances Lean Tissue Accretion by Increasing Muscle Amino Acid Transport and Protein Turnover Compared with Continuous Feeding in Neonates

Orogastric tube feeding is recommended in neonates unable to ingest food normally, and can be administered by intermittent bolus (INT) or continuous (CON) infusion. Recently, we showed that INT compared to CON feeding enhances lean tissue accretion by increasing muscle protein synthesis in neonates. To determine the mechanism for this response, neonatal pigs (n=6, 6‐d‐old) were fed the same diet in equivalent amounts continuously or intermittently (meal every 4h) for 21d. Insulin receptor and insulin receptor substrate 1 expression and protein kinase B phosphorylation in skeletal muscle were unaffected by feeding modality. Formation of the active eukaryotic initiation factor (eIF) 4E‐eIF4G complex and phosphorylation of ribosomal protein S6 kinase were higher and phosphorylation of eIF2α was lower in INT compared to CON fed pigs indicating increased translation initiation (P&lt;0.05). Sodium‐coupled neutral amino acid transporter 2, but not L‐type amino acid transporter 1, expression was higher in INT compared to CON pigs suggesting enhanced glutamine transport (P&lt;0.05). Abundance of the ubiquitin ligases, muscle RING finger‐1 and F‐box protein atrogin‐1/MAFbx, was higher for INT compared to CON pigs (P&lt;0.05). These results suggest that intermittent feeding enhances lean tissue accretion by increasing amino acid transport and protein turnover. (Supported by NIH AR444474 and USDA/ARS 6250–51000‐055)

Esophagus and Its Function Related to Gastro-esophageal Reflux

ABSTRACT The main function of the esophagus is to transport food from the mouth into stomach. Anatomical structures, innervations and blood supplies are needed in order to transport the food into stomach. Mastication stimulates the parasympathetic nerves that regulate salivary, gastric and pancreatic secretion. Saliva secretion stimulates swallowing and increases primary esophageal peristalsis, helps in clearing the esophagus from refluxed material. Swallowing induces peristaltic of esophagus that propulses a solid bolus down the esophagus into the stomach. Innervations are important for esophagus to do its function. One of the most important is coordination between the various reflexes. Delayed clearance of acid from the esophageal and decreased pressure of the lower sphincter esophagus (LES) are the major mechanisms involved in the development of esophagitis. The resistance of the mucosa to the noxious effect of the refluxed material (acid, pepsin, chymotrypsin and trypsin, bile, etc.) is different from person to person. The LES pressure is a defense mechanisms to prevent gastro-esophageal reflux disease ( xe GERD). The LES pressure decreases postprandially. The frequency of postprandinal GER is related to the meal size. Gastric bolus feeding is related to greater intragastric pressure causes more of transient LES relaxations. Osmolality and volume of the feeding slow gastric emptying and incrase postprandial GER. The occurrence of xe GERD is associated with whether or not the preventive factors are functioning. Other preventive factors for xe GERD are esophageal peristalsis, secretion and mucosal resistance, gravity and position, the LES tone and angle of his. Patient with xe GERD should be searched for any disturbances on those factors. Keywords: gastroesophageal reflux diseases, lower esophageal sphincter, esophagitis, peristaltic

Casein addition to a whey-based formula has limited effects on gut function in preterm pigs1

Preterm infants are susceptible to necrotizing enterocolitis (NEC). Using preterm pigs, we determined whether a whey-casein-based formula would be superior to a formula based on whey protein alone. Twenty cesarean-derived preterm pigs (92% gestation) were given total parenteral nutrition for 36 h followed by 30 h of enteral feeding with whey [protein fraction of milk formula based on whey (WHEY); n = 11] or casein and/or whey [protein fraction of milk formula based on a combination of casein and whey (CASEIN); n = 9]-based formulas. Sugar absorptive function was investigated at 6 and 30 h after initiation of enteral feeding using bolus feedings with galactose and mannitol. Pigs were killed after the last in vivo sugar absorption test and evaluated for NEC and the mid intestine was used for ex vivo measurements of hexose absorption. Microbiota profile and short chain fatty acid (SCFA) levels were studied in gut contents. Severity of NEC lesions was similar between diet groups but galactose absorption was markedly higher in CASEIN than in WHEY (P < 0.01) although only 6 h after the start of the enteral feeding period. There were no differences in ex vivo (14)C-D-glucose uptake, digestive enzymes, microbiota profile, or SCFA concentration. Casein may transiently stimulate intestinal sugar absorption but has limited effects on gut structure, microbiota, and NEC in preterm pigs.

346 Effects of Bolus and Continuous Enteral Feeding on Splanchnic and Cerebral Tissue Oxygenation Evaluated by Near Infrared Spectroscopy

Background and AimsBolus and continuous tube feeding represent the most frequently used enteral feeding techniques in preterm infants, but the best strategy is not yet established. Near-Infrared-Spectroscopy (NIRS) provides a...

Automated dynamic fed‐batch process and media optimization for high productivity cell culture process development

Current industry practices for large-scale mammalian cell cultures typically employ a standard platform fed-batch process with fixed volume bolus feeding. Although widely used, these processes are unable to respond to actual nutrient consumption demands from the culture, which can result in accumulation of by-products and depletion of certain nutrients. This work demonstrates the application of a fully automated cell culture control, monitoring, and data processing system to achieve significant productivity improvement via dynamic feeding and media optimization. Two distinct feeding algorithms were used to dynamically alter feed rates. The first method is based upon on-line capacitance measurements where cultures were fed based on growth and nutrient consumption rates estimated from integrated capacitance. The second method is based upon automated glucose measurements obtained from the Nova Bioprofile FLEX® autosampler where cultures were fed to maintain a target glucose level which in turn maintained other nutrients based on a stoichiometric ratio. All of the calculations were done automatically through in-house integration with a Delta V process control system. Through both media and feed strategy optimization, a titer increase from the original platform titer of 5 to 6.3 g/L was achieved for cell line A, and a substantial titer increase of 4 to over 9 g/L was achieved for cell line B with comparable product quality. Glucose was found to be the best feed indicator, but not all cell lines benefited from dynamic feeding and optimized feed media was critical to process improvement. Our work demonstrated that dynamic feeding has the ability to automatically adjust feed rates according to culture behavior, and that the advantage can be best realized during early and rapid process development stages where different cell lines or large changes in culture conditions might lead to dramatically different nutrient demands.