Search

Background α-1-syntrophin (SNTA1), a protein encoded by SNTA1, is highly expressed in human cardiomyocytes. Mutations in SNTA1 are associated with arrhythmia and cardiomyopathy. Previous research on SNTA1 has been based on nonhuman cardiomyocytes. Our study was designed to identify phenotype of SNTA1-deficient using human cardiomyocytes. Methods SNTA1 was knocked out in H9 cell line using CRISPR-Cas9 system. H9SNTA1KO cells were then induced to differentiate into cardiomyocytes using small molecule inhibitors. The phenotypic discrepancies associated with SNTA1-deficient cardiomyocytes were investigated. Results SNTA1 was truncated in PH1 domain by a stop codon (TGA) using CRISPR-Cas9 system. SNTA1-deficient did not affect the pluripotency of H9SNTA1KO, and they retain their in vitro ability to differentiate into cardiomyocytes. However, H9SNTA1KO derived cardiomyocytes exhibited increased structural components, weak calcium transient intensity, low levels of calcium in sarcoplasmic reticulum, lower cardiac contractility, and shorter field potential duration. Early treatment of SNTA1-deficient cardiomyocytes with ranolazine improved the calcium transient intensity and cardiac contractility. Conclusions SNTA1-deficient cardiomyocytes can be used to research the etiology, pathogenesis, and potential therapies for myocardial diseases. The SNTA1-deficient cardiomyocyte model suggests that the maintenance of cardiac calcium homeostasis is a key target in the treatment of myocardial-related diseases.

Objective To determine the prevalence of post traumatic stress disorder (PTSD) in the army officers and soldiers (AOSs), and identify its relationship with functional gastrointestinal disorders (FGIDs). Methods PTSD and FGIDs were diagnosed based on the PTSD checklist-civilian (PCL-C) and Rome Ⅲ Modular Questionnaire respectively, the overlaps of PTSD and FGIDs and their correlation were diagnosed. The correlation of PTSD with traumatic and stressful events was investigated using Trauma History and Stressful Event Screening Questionnaire. The coexistence and relationship of PTSD and FGIDs were analyzed. Results Of 927 AOSs, 33 were diagnosed with PTSD. The prevalence of PTSD was 3.56%. FGIDs were identified in 435 subjects and the incidence of FGIDs was 46.93%. Among 33 AOSs with PTSD, 28 were diagnosed as having FGIDs and the prevalence of FGIDs was 84.85%, which was significantly higher than that of non-PTSD group (45.53%, P

To investigate the effects and possible mechanisms of action of Curcuma wenyujin Y. H. Chen et C. Ling n-Butyl alcohol extract (CWNAE) on repression of human gastric cancer (GC) AGS cell invasion induced by co-culturing with Helicobacter pylori (HP). AGS cells were cultured with HP of positive or negative cytotoxin-associated gene A (CagA) and vacuolating cytotoxin gene A (VacA) expression (CagA+/- or VacA+/-) and divided into 5 group. Group A was cultured without HP as a control, Group B with HPCagA+VacA+, Group C with HPCagA-VacA-, Group D with HPCagA+VacA+ and CWNAE, and Group E with HPCagA-VacA- and CWNAE. Methylthiazolyldiphenyl-tetrazolium bromide (MTT) and tumor invasion assays, examinations of morphology and ultramicroscopic structures, quantitative real-time polymerase chain reaction and Western blots were performed to measure the effects and uncover the mechanisms behind these effects of HPCagA+VacA+ and CWNAE on the epithelial-mesenchymal transition (EMT) of AGS cells. The 10% inhibitory concentration of CWNAE against AGS cells after a 48 h incubation was 19.73±1.30 μg/mL. More AGS cells were elongated after co-culturing with HPCagA+VacA+ than after culturing with HPCagA-VacA-. In tumor invasion assays, HPCagA+VacA+ significantly enhanced the invasiveness of AGS cells compared to the other experimental groups (all P value

Background: In 2010, undifferentiated early-stage gastric cancers (EGCs; ≤1 cm and confined to the mucosa) were included in the expanded criteria for endoscopic submucosal dissection (ESD), as established by the Japanese Gastric Cancer Association. Objective: To evaluate the safety and efficacy of the newly expanded criteria of ESD for EGCs. Methods: PubMed, Embase, and the Cochrane Library were searched for relevant studies published between January 1, 2010 and July 10, 2014. These studies were collected by 2 authors and then analyzed with RevMan 5.0. Results: Six studies including 6,687 patients were identified. Compared to the standard group (SG), the expanded group (EG) had higher bleeding (OR 1.66; 95% CI 1.02-2.68), perforation (OR 2.03; 95% CI 1.25-3.31), positive lateral margin rates (OR 16.88; 95% CI 3.83-74.5) and lower en bloc resection rate (OR 0.48; 95% CI 0.34-0.70). The local recurrence (OR 2.46; 95% CI 0.31-19.23) and total survival rates (OR 0.92; 95% CI 0.76-1.12) between the 2 groups were not statistically different. Conclusions: Considering the similar rates of local recurrence and total survival between the SG and EG, the use of ESD for the management of EGCs that meet the expanded criteria could be considered a safe and effective treatment method.

To investigate the effects and possible mechanisms of action of Curcuma wenyujin Y. H. Chen et C. Ling n-Butyl alcohol extract (CWNAE) on repression of human gastric cancer (GC) AGS cell invasion induced by co-culturing with Helicobacter pylori (HP).AGS cells were cultured with HP of positive or negative cytotoxin-associated gene A (CagA) and vacuolating cytotoxin gene A (VacA) expression (CagA+/- or VacA+/-) and divided into 5 group. Group A was cultured without HP as a control, Group B with HPThe 10% inhibitory concentration of CWNAE against AGS cells after a 48 h incubation was 19.73±1.30 μg/mL. More AGS cells were elongated after co-culturing with HPHP

Excavation of the soil is actually the unloading process. The unloading process of soil makes the soil uplift, and the soil uplift is restricted by the pit engineering piles. And then, engineering piles should bear the vertical upwards pulling force caused by soil uplift. When pulling force is huge and tensile bearing capacity of pile is low, engineering piles could be pulled apart, and it is harmful to bearing capacity and durability of engineering piles. This paper adopts the finite element method to simulate engineering piles during pit excavation, and studies the traits of engineering piles in various excavation working conditions and different position. The computational results show that the deeper pit, the bigger displacement and tensile forces of piles, and the farther away from edges of the pit, the bigger displacement and forces of piles. In addition, the paper also gives a formula about the relationship between depth of pit excavation and uplift force on piles.

During the 1980s, a novel nonvolatile memory product was introduced, referred to as flash electrically erasable program-mable read-only memory (EEPROM). The basic operating prin-ciple of the nonvolatile memory device is to store charges in the gate oxide of a metal-oxide semiconductor field-effect transistor (MOSFET). If charges can be stored in the oxide of a MOSFET, the threshold voltage of the MOSFET can be modified to switch between two distinct values, conventionally defined as the erase state and the program state. The terms erase and program are used to denote operations that charge and discharge through ox-ide. The threshold voltage shift between the two states is caused by the storage of charge in oxide. The program state is usually obtained from a channel hot electron, while the erase state uses Fowler-Nordheim (F-N) tunneling through a thin gate oxide. The storage of charges in the gate oxide of the nonvolatile memory device can be realized by surrounding a conducting layer by an oxide. Since this layer acts as a completely electrically isolated gate, this type of device is commonly referred to as a floating gate device.An EEPROM cell containing an n-well and metal-insulator-metal (MIM) capacitor was fabricated using a 0.18 μm stan-dard complementary MOS (CMOS) process. In recent efforts, a stacked metal-insulator-metal (MIM) and an n-well capacitor have been applied to a single polysilicon EEPROM cell in order to increase memory capacity [1-4]. The application of the single polysilicon EEPROM is becoming more popular due to its low process cost and satisfactory reliability [5-7]. Optimal charac-teristics of EEPROM include fast program/erase speed, high endurance performance, and low leakage current. Although the MIM capacitor cell performs well, it requires a large device-size. The n-well control gate cell inherently possesses high junction capacitance and high sheet resistance. In this paper, we propose an EEPROM cell that does not re-quire additional cell area in order to obtain a high capacitance. Additionally, the proposed EEPROM provided a satisfactory control gate coupling ratio contributing to the junction capaci-tance between the control gate and the n-well. Because the n-well depletion capacitor was isolated by shallow trench iso-lation (STI) and the MIM capacitor was located just above the n-well capacitor, the cell containing two capacitors connected in parallel was expected to be very reliable and to provide noise immunity.

The influence of iron-complexed ehylenediaminetetraacetic acid (EDTA) was studied on nitric oxide (NO) removal using photoautotropic cultivation of green alga Scenedesmus. Fe(II)EDTA is an active solubilization agent of NO in water, while the oxidized Fe(III)EDTA is not. When a gas mixture containing 300 ppm NO was treated through the Scenedesmus culture containing 5 mM Fe(II)EDTA, a constant level of 80–85% NO removal was achieved for a prolonged period. A certain fraction of Fe(II)EDTA remained without being oxidized to Fe(III)EDTA because of the existence of reversible oxidation–reduction balance between Fe(II)EDTA and Fe(III)EDTA. When Fe(III)EDTA was added to the culture instead of Fe(II)EDTA, Fe(II) was generated via reduction of Fe(III), resulting in the increase of NO removal and cell density. This was possible because of the generated Fe(II)EDTA which contributed to the dissolution of NO. Therefore, a long-term NO removal was possible with Fe(III)EDTA, as well as with Fe(II)EDTA, in the present microalgal system. The supplementation of free EDTA was necessary to extend the period of NO removal because EDTA is consumed by biodegradation while the decrease of total iron content was not significant.

The green alga Scenedesmus was investigated for its ability to remove nitrogen from anaerobic digestion effluent possessing high ammonium content and alkalinity in addition to its growth characteristics. Nitrate and ammonium were indistinguishable as a nitrogen source when the ammonium concentration was at normal cultivation levels. Ammonium up to 100ppm NH(4)-N did not inhibit cell growth, but did decrease final cell density by up to 70% at a concentration of 200-500ppm NH(4)-N. Inorganic carbon of alkalinity in the form of bicarbonate was consumed rapidly, in turn causing the attenuation of cell growth. Therefore, maintaining a certain level of inorganic carbon is necessary in order to prolong ammonia removal. A moderate degree of aeration was beneficial to ammonia removal, not only due to the stripping of ammonium to ammonia gas but also due to the stripping of oxygen, which is an inhibitor of regular photosynthesis. Magnesium is easily consumed compared to other metallic components and therefore requires periodic supplementation. Maintaining appropriate levels of alkalinity, Mg, aeration along with optimal an initial NH(4)(+)/cell ratio were all necessary for long-term semi-continuous ammonium removal and cell growth.

A simulation study of a current‐mode direct current (DC)‐DC buck converter is presented in this paper. The converter, with a fully integrated power module, is implemented by using sense method metal‐oxide‐semiconductor field‐effect transistor (MOSFET) and bipolar complementary metal–oxide–semiconductor (BiCMOS) technology. When the MOSFET is used in a current sensor, the sensed inductor current with an internal ramp signal can be used for feedback control. In addition, the BiCMOS technology is applied in the converter for an accurate current sensing and a low power consumption. The DC‐DC converter is designed using the standard 0.35 μm CMOS process. An off‐chip LC filter is designed with an inductance of 1 mH and a capacitance of 12.5 nF. The simulation results show that the error be‐ tween the sensing signal and the inductor current can be controlled to be within 3%. The characteristics of the error amplification and output ripple are much improved, as compared to converters using conventional CMOS circuits.

The characteristics of hydrogen production using immobilized cyanobacterium Microcystis aeruginosa were studied through a two-stage cyclic process. Immobilized cells were first grown photosynthetically under CO2 and light, followed by anaerobic H2 production in the absence of light and sulfur. M. aeruginosa was capable of generating H2 under immobilized conditions, and the use of immobilized cells allowed the maintenance of stable production and sped up the changes in culture conditions for cyclic two-stage operation. M. aeruginosa was also capable of utilizing exogenous glucose as a substrate to generate hydrogen and 30 mM concentration proved to be optimal. The externally added glucose improved H2 production rates, total produced volume and the lag time required for cell adaptation prior to H2 evolution. The rate of hydrogen evolution was increased as temperature increased, and the maximum evolution rate was 48 mL/h/L and 34.0 mL/h/L at 42 °C and 37 °C, respectively. The optimal temperature for hydrogen production was 37–40 °C because temperatures higher than 42 °C resulted in cell death. In order to continue repeated cycles of H2 production, at least two days of photosynthesis under conditions with light, CO2, and sulfur should be allowed for cells to recover H2 production potential and cell viability.

A photoautotrophic cultivation of green algae Scenedesmus cells was used for the removal of nitric oxide (NO) from a model flue gas mixture. In an attempt to improve the solubility of NO in the culture broth, the addition of Fe(II)EDTA to the cultivation was investigated. The addition of Fe(II)EDTA greatly enhanced NO-dissolution in the culture broth and subsequently increased the algal-uptake of NO. NO was assimilated as a source of nitrogen for the growth of Scenedesmus cells since there was a steady increase in cell density with no other nitrogen source in the culture except the incoming NO. 40–45% of NO removal was maintained for more than 12 days with the addition of 5 mM Fe(II)EDTA in a 1-L air-lift type photobioreactor system fed with 300 ppm of NO gas at a rate of 0.3 wm. However, the NO-dissolution-enhancing capacity of Fe(II)EDTA did not reach its full potential due to its oxidation to Fe(III)EDTA, possibly induced by molecular oxygen that evolved from algal photosynthesis, and subsequent loss of chelating capabilities.

To study the role of nuclear factor (NF)-kappaB pathway with p38MAPK in Curcuma wenyujin diterpenoid compound C (CDCC) fighting against inflammation and inducing gastric cancer cell apoptosis by stimulating gastric cell SGC7901 with tumor necrosis factor-alpha (TNF-alpha).Human umbilical vein endothelial cells (HUVECs) and human gastric cancer SGC-7901 cells were in vitro acted by CDCC in different concentrations at different time points. Their growth inhibition ratios were measured by MTT assay. The apoptosis rate of gastric cancer cells was detected by Annexin V-FITC/PI double staining. Nuclear translocation of p65 was detected by cell immunofluorescence. Expression levels of p38MAPK/P-p38MAPK, p65/P-p65, and Caspase 3/P-Caspase 3 were measured by Western blot.CDCC had significant inhibitory effect on the proliferation of SGC-7901. It also could effectively induce the apoptosis of gastric cancer cell SGC-7901. It also could reduce nuclear translocation of p65 in gastric cancer cell SGC-7901. Results of Western blot indicated that expression levels of p38MAPK and p65 were reduced and the expression level of Caspase-3 was elevated along with increased concentrations of CDCC (P0.05).Apoptosis executive protein Caspase 3 activated by regulating p65 via p38MAPK might be one of possible mechanisms for CDCC fighting against inflammation and gastric cancer.

Background: Leflunomide (LEF) and benazepril have renoprotective effects on diabetic nephropathy (DN) through their anti-inflammatory and anti-fibrotic activities. This study investigated whether combined treatment using LEF and benazepril affords superior protection compared with the respective monotherapies. Methods: Diabetes was induced with streptozotocin (STZ, 65 mg/kg) by intraperitoneal injection in male Wistar rats. Two weeks after STZ injection, diabetic rats were treated daily for 12 weeks with LEF (10 mg/kg), benazepril (10 mg/kg), or a combination of both. Basic parameters (body weight, fasting blood glucose level, and 24 h urinary protein excretion), histopathology, inflammatory [inflammatory cell infiltration (ED-1), monocyte chemoattractant protein-1 (MCP-1), and Toll-like receptor-2 (TLR-2)] and glomerulosclerotic factors [transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF)], and oxidative stress (8-hydroxy-2'-deoxyguanosine, 8-OHdG) were studied. Results: Benazepril or LEF treatment significantly prevented body weight loss and 24 h urinary protein excretion induced by diabetes; combined treatment with LEF and benazepril further improved these parameters compared with giving each drug alone (all p < 0.01). Increased expression of inflammatory (MCP-1 and TLR-2) and glomerulosclerotic (TGF-β1 and CTGF) factors in diabetic rat kidney was reduced by treatment with either LEF or benazepril and was further reduced by the combined administration of the two drugs (p < 0.01). These effects were accompanied by suppression of urinary 8-OHdG excretion. There was no significant between-group difference in blood glucose level. Conclusions: LEF treatment lessens DN, and combined treatment with LEF and benazepril provides synergistic effects in preventing DN.

To investigate the dynamic expression of p-signal transducer and activator of transcription 3 (STAT3) and vascular endothelial growth factor (VEGF) in the formation of gastric tumors induced by drinking water containing N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Wistar rats.One hundred and twenty Wistar rats were randomly divided into two groups (60 in each group): Control group and Model group. The rats in each group were then randomly divided into three groups (20 in each group): C/M15, C/M25 and C/M40 (15, 25 and 40 represent the number of feeding weeks from termination). Rats in the control group received normal drinking water and rats in the model group received drinking water containing 100 μg/mL MNNG. Stomach tissues were collected at the end of the 15(th), 25(th) and 40(th) week, respectively, for microscopic measurement using hematoxylin and eosin staining. The expression of p-STAT3 and VEGF in different pathological types of gastric tissue, including normal, inflammation, atrophy, hyperplasia and gastric stromal tumor, was observed by immunohistochemistry and Western blot, and the corelation between p-STAT3 and VEGF was analyzed.(1) The expression of p-STAT3 in tissue with gastritis, atrophy, dysplasia and gastric stromal tumor were significantly increased in the model group compared with the control group (2.5 ± 1.0, 2.75 ± 0.36, 6.2 ± 0.45, 5.67 ± 0.55 vs 0.75 ± 0.36, P = 0.026, 0.035, 0.001, 0.002, respectively); the expression of p-STAT3 in tissue with dysplasia was higher than that in samples with gastritis or atrophy (6.2 ± 0.45 vs 2.5 ± 1.0, P = 0.006; 6.2 ± 0.45 vs 2.75 ± 0.36, P = 0.005, respectively); however, the expression of p-STAT3 in gastritis and atrophy was not significantly different (P0.05); (2) the expression of VEGF in tissue with gastritis, atrophy, dysplasia and gastric stromal tumor was significantly increased in the model group compared with normal gastric mucosa; and the expression of VEGF in tissue with dysplasia was higher than that in tissue with inflammation and atrophy (10.8 ± 1.96 vs 7.62 ± 0.25, P = 0.029; 10.8 ± 1.96 vs 6.26 ± 0.76, P = 0.033, respectively); similarly, the expression of VEGF in tissue with gastritis and atrophy was not significantly different (P0.05); and (3) the expression of VEGF was positively correlated with p-STAT3.p-STAT3 plays an important role in gastric cancer formation by regulating the expression of VEGF to promote the progression of gastric tumor from gastritis.

This paper introduces the design and implementation of a novel current cell in current-steering digital-to-analog converter (DAC). The current cell consists of current switch and source which are independently controlled by latch. A sequential switch-on process similar to thermometer decoding is implemented in source to reduce the power consumption. A 12-b DAC has been fabricated using a single-poly four-metal 0.35 µm CMOS process. Comparison with conventional DAC shows that the proposed DAC produces a power reduction in the order of 35% without degradation of linearity. Two sub-DACs are composed of 8-bit unary matrix type and 4-bit binary type. The least significant bits (LSB's) steer a binary array, while the most significant bits (MSB's) are thermometer coded and steer a unary array. The two major blocks of DAC circuit are the digital and the cell array block. With an increase in the number of bit, the most power in current steering DAC is consumed in the cell array block. Therefore, low power cell operation is essential to reduce the overall DAC power consumption.

OBJECTIVE: To investigate the cytotoxicity of silk fibroin/gelatin (SF/G) composite scaffolds in vitro as well as their biocompatibility and degradation in vivo. METHODS: The proliferation and relative growth rate of human hepatic QZG cells grown on different blends of two-dimensional (2-D) SF/G scaffolds were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Flow cytometry was used to evaluate apoptotic rate of QZG cells on different blends of 2-D SF/G scaffolds. The effect of silk protein materials on cell growth was observed by scanning electron microscopy. Three-dimensional (3-D) SF/G scaffolds of three different ratios (diameter 10 mm, thickness 1 mm) were implanted into subcutaneous pockets on male Sprague–Dawley (SD) rats. On the 7th, 14th and 30th day post-implantation, the rats were sacrificed. The scaffold area including the surrounding tissues was retrieved. Hematoxylin and eosin staining was performed for observation under a light microscope. RESULTS: Significant cell attachment and proliferation on the SF/G scaffolds were observed. As the increased gelatin concentration, SF/G scaffolds became more amenable to cell adhesion. After the subcutaneous implantation of the SF/G scaffolds in SD rats, immunological rejection tests showed only slight inflammation, measured by the presence of inflamed cells on day 7 and 14. By day 30, each scaffold had been completely infiltrated and organized by fibroblasts and inflamed cells. The greater the gelatin concentration in the scaffold, the faster the degradation rate. CONCLUSION: Composite SF/G scaffolds are a promising candidate matrix for implantable bio-artificial livers.

Reprogramming human somatic cells to pluripotency represents a valuable resource for research aiming at the development of in vitro models for human diseases and regenerative medicines to produce patient-specific induced pluripotent stem (iPS) cells. Seeking appropriate cell resources for higher efficiency and reducing the risk of viral transgene activation, especially oncogene activation, are of significance for iPS cell research. In this study, we tested whether human amnion-derived cells (hADCs) could be rapidly and efficiently reprogrammed into iPS cells by the defined factors: OCT4/SOX2/NANOG. hADCs from normal placenta were isolated and cultured. The 3rd passage cells were infected with the lentiviral vectors for the delivery of OCT4, SOX2, and NANOG. Afterwards, the generated iPSCs were identified by morphology, pluripotency markers, global gene expression profiles, and epigenetic status both in vitro and in vivo. The results showed that we were able to reprogram hADCs by the defined factors (OCT4/SOX2/NANOG). The efficiency was significantly high (about 0.1%), and the typical colonies appeared on the 9th day after infection. They were similar to human embryonic stem (ES) cells in morphology, proliferation, surface markers, gene expression, and the epigenetic status of pluripotent cell-specific genes. Furthermore, these cells were able to differentiate into various cell types of all three germ layers both in vitro and in vivo. These results demonstrate that hADCs were an ideal somatic cell resource for the rapid and efficient generation of iPS cells by OCT4/SOX2/NANOG.

To evaluate the preventive potential of intraoperative or early postoperative local administration of peptide PIII into the abdominal cavity against peritoneal carcinomatosis.Human gastric cancer cells of the line GC9811 were inoculated subcutaneously into nude mice to cause subcutaneous carcinoma. The 8th generation cancer was taken out to isolate the cancer cells to be inoculated into the serous membrane at the greater curvature of the stomach. Forty-eight nude BALB/C-nu/nu mice underwent implantation of the 8th generation cancer cells into the serous membrane at the greater curvature of the stomach via minilaparotomy so as to establish models of peritoneal carcinoma The 48 mice were randomly divided into 3 equal groups: Group 1 (control group); Group 2, undergoing intraperitoneal perfusion of 100 microg of peptide PIII, and post-operative intraperitoneal perfusion of 2 mg/kg peptide PIII twice; and Group 3, undergoing post-operative intraperitoneal perfusion of 100 microg/kg peptide PIII twice. Six mice in every group were sacrificed on the day 23 to undergo pathological examination. The other mice in every group were used to evaluate the survival rate. The tumor-bearing mice showing manifestations of failure were killed to undergo pathology.The weight of individual tumor was not significantly different among the 3 groups. The number of peritoneal metastatic nodules of Group 2 was (9.2 +/- 1.3), significantly less than those of Group 1 and 3 [(126.3 +/- 9.6) and (64.2 +/- 8.3) respectively, both P0.01]. The number of metastatic nodules2 mm of Group 2 was 1.6 +/- 0.2, significantly less then those of Groups 1 and 3 [(51.2 +/- 3.6) and (21.7 +/- 4.9) respectively, both P0.01]. The survival rate of Group 2 was significantly longer than those of Groups 1 and 3 (both P0.01).Peptide PIII does not significantly inhibit the growth of GC, but significantly reduce the peritoneal metastasis of GC. An ideal targeting chemotherapy, intra-operative application of peptide PIII into the abdominal cavity plus intraperitoneal perfusion is an attractive and promising strategy to prevent peritoneal metastasis of GC.

In this study, the effects of nitrate feeding on microalgal growth and associated CO2 fixation were evaluated, as a strategy to enhance carbon fixation by increasing the duration of the exponential phase of cell growth in the batch operation of a photobioreactor. Two species of green algae, Chlorella and Scenedesmus, and two species of cyanobacteria, Microcystis ichthyoblabe and Microcystis aeruginosa, were used after adaptation to a 15% (v/v) CO2 environment. In the absence of nitrate feeding, nitrate concentrations declined rapidly and soon became a limiting factor. Nitrate feeding, administered in fed-batch mode to maintain 15-20 ppm of NO3-N, allowed for an extension of the exponential growth phase by more than 3 days, as well as a higher cell density, which subsequently resulted in an increase in photoautotrophic carbon fixation. The increases in the carbon fixation rate were in the ranges of 56.1-56.6% for the green algae, and between 68.2-68.8% for the cyanobacteria. The results indicated that intermittent nitrate feeding was a viable strategy for the augmentation of fixation productivity, and may thus be effectively applied as a substitute for conventional medium change, which has traditionally been employed in order to prolong the active growth duration.