[Application of 3D-CT simulation image in the description of gastric artery variation to guide laparoscopic total gastrectomy]

Objective: Anatomic variations in the perigastric vessels during laparoscopic radical gastrectomy often affect the operator's judgment and prolong the operation time, and even cause accidental injury and surgical complications, and hence the safety and quality of the operation cannot be ensured. In this study, multiple slice CT was reconstructed by 3-dimensional CT simulation software (3D-CT), and 3D-CT images were used to describe the variation of celiac trunk and splenic artery before surgery. The guiding role of the different variation of vessels was analyzed for laparoscopic total gastrectomy+D2 lymph node dissection (LTG+D2LD). Methods: A retrospective cohort study was conducted. Case inclusion criteria: (1) Gastric cancer was at an advanced stage. All the patients were preoperatively examined by digestive endoscopy and 64-row enhanced CT scan, and were histopathologically diagnosed with gastric adenocarcinoma. (2) 3D-CT simulation images were reconstructed to guide the operation. (3) LTG+D2LD surgery was performed by the same surgical team. (4) Clinical data were complete, and all the patients had signed the informed consent. From 2014 to 2018, 98 patients with gastric cancer at the Gastrointestinal Surgery Department of Henan Provincial People's Hospital were enrolled. According to the Adachi classification, celiac trunk variation was divided into common type (Adachi type I) and rare type (Adachi type II-VI). According to the Natsume classification, splenic artery was classified into "flat type" and "curved type". Based on 3D-CT simulation images, variation of celiac trunk and splenic artery was described, and the differences in operation time, intraoperative blood loss and the number of postoperative retrieved lymph nodes were compared between groups with different types of arterial variation. Results: For celiac trunk, common type was found in 84 cases (86%) and rare type was found in 14 cases, including 6 cases (6%) of type II, 2 cases (2%) of type III, 2 cases (2%) of type IV, 3 cases (3%) of type V, 1 case (1%) of type VI. No other types were found. There were no statistically significant differences in clinical characteristics and number of retrieved lymph nodes between patients of the common type group and rare type group (all P>0.05). Compared with common type patients, those of rare type had longer operative time [(321.1±29.0) minutes vs. (295.1±46.5) minutes, t=2.081, P=0.040] and more intraoperative blood loss (median: 66.0 ml vs. 32.0 ml, Z=-4.974, P=0.001). For splenic artery, 41 patients (42%) were flat type and 57 patients (58%) were curved type. There were no statistically significant differences between the two groups in terms of clinical characteristics, intraoperative blood loss, operative time and number of retrieved lymph nodes (all P>0.05). Conclusions: The method of describing the variation in the perigastric vessels by 3D-CT simulation has certain clinical value in laparoscopic radical gastrectomy. The duration of LTG+D2LD is prolonged and the intraoperative blood loss is increased with the variation of celiac trunk, while the variation of splenic artery has no effect on LTG+D2LD.

Identifying Efficient Transport Pathways in Early-Wood Timber: Insights from 3D X-ray CT Imaging of Softwood in the Presence of Flow

Wider use of timber has the potential to greatly reduce the embodied carbon of construction. Improved chemical treatment could help overcome some of the barriers to wider application of timber, by furthering the durability and/or mechanical properties of this natural material. Improving timber treatment by treating the whole volume of a piece of timber, or tailored sections thereof, requires sound understanding and validated modelling of the natural paths for fluid flow through wood. In this study we carry out a robust analysis of three-dimensional X-ray CT measurements on kiln-dried softwood in the presence of flow and identify small portions of early-wood which are uniquely capable of transporting fluids—herein ‘efficient transport pathways’. We successfully model the effects of these pathways on the liquid uptake by timber by introducing a spatial variability in the amount of aspiration of the bordered pits following kiln drying. The model demonstrates that fluid advances along these efficient transport paths between 10 and 30 times faster than in the remainder of the timber. Identifying these efficient transport pathways offers scope to improve and extend the degree to which timber properties are enhanced at an industrial scale through processes to impregnate timber.

[The application of 3-dimensional shear wave elastography in the therapeutic effect evaluation of neoadjuvant chemotherapy for Her-2 positive breast cancer patients]

Objective: To investigate the clinic value of ultrasound 3-dimensional shear wave elastography (3D-SWE) in therapeutic effect evaluation of neoadjuvant chemotherapy (NAC) for HER-2 positive breast cancer patients. Methods: A total of 43 lesions from 43 HER-2 positive breast cancer patients were selected and all of the lesions were confirmed by biopsy. Ultrasound examination was performed routinely before each chemotherapy cycle. The interested regions were selected under the 3-dimensional (3D) elasticity and gray-scale mode, the relevant data such as shear waves in the transverse, longitudinal and coronal sections of the mass were generated automatically. According to the histopathological results, the patients were divided into the pathological complete remission (pCR) group and the incomplete remission (non-pCR) group. The maximum elastic hardness value (Emax) and the reduction degree (ΔEmax) of the lesions in the two groups were measured and compared in each cycle of NAC. The accuracy of 3D-SWE technique for predicting the efficacy of NAC was evaluated using indicators such as sensitivity, specificity and area under the receiver operating characteristic (ROC) curve. Results: The clinicopathologic features between pCR group (18 cases) and non-pCR Group (25 cases) were not significantly different (P>0.05). Compared with pre-chemotherapy, the Emax values of pCR group and non-pCR Group during chemotherapy were declined (P<0.05). Moreover, the Emax values of pCR group before and after chemotherapy were lower than those of non-pCR group (P<0.05). At the end of the first cycle of chemotherapy, the predictive specificity, sensitivity and area under the curve (AUC) of pCR group were 72.0%, 83.3% and 0.838 (95%CI=0.680~0.930) respectively when the cutoff value of Emax was 118 kPa. At the end of the second cycle, the predictive specificity, sensitivity and AUC of pCR group were 76.0%, 83.3% and 0.863 (95%CI=0.720~0.940) respectively when the cutoff value of Emax was 87 kPa. At the end of the third cycle, the predictive specificity and sensitivity and the AUC of the pCR group were 88.0%, 77.8% and 0.893 (95%CI=0.760~0.970) when the cutoff value of Emax was 57 kPa. At the end of the fourth cycle of chemotherapy, the predictive specificity, sensitivity and AUC of pCR group were 92.5%, 88.9% and 0.960 (95%CI=0.850~0.990) respectively when the cutoff value of Emax was 30 kPa. After one cycle of NAC, the predictive sensitivity and specificity and AUC of pCR group were 88.0%, 60.0%, and 0.719 (95%CI=0.620~0.890) when the cutoff value of ΔEmax was 16.8%. After two cycles, the predictive sensitivity, specificity and AUC of pCR group were 55.5%, 80.0% and 0.712 (95%CI=0.550~0.840) when the cutoff value of ΔEmax was 34.9%. After three cycles, the predictive sensitivity, specificity and AUC of pCR group were 67.4%, 81.2% and 0.779 (95%CI=0.680~0.930) when the cutoff value of ΔEmax was 55.2%. After four cycles, the predictive sensitivity, specificity and AUC of pCR group was 72.3%, 92.0% and 0.831 (95%CI=0.690~0.930) when the cutoff value of ΔEmax was 75.1%. Conclusion: The Emax and ΔEmax values measured by 3D-SWE technology can predict the curative effect of NAC for breast cancer.

Bioactive metabolites in of Ginkgo biloba leaves: variations by seasonal, meteorological and soil

Ginkgo biloba is a traditional Chinese herbal medicine containing multiple components that contribute to its notable bioactivities. Variations of seasonal, meteorological and planting soil on the phytochemicals contents in G. biloba leaves due to the effects of growth meteorological and soil parameters were investigated in this study. The leaves of G. biloba were collected from different months and place in Zhejiang province, the contents of flavones (quercetin, kaempferol and isorhamnetin) and terpene lactones (bilobalide, ginkgolides A, B and C) were quantified by high performance liquid chromatography (HPLC) and the evaporative light scattering detector (ELSD) method. The established methods were validated with good linearity, precision, repeatability, stability, and recovery. Comprehensive analysis suggested the proper harvest time for G. biloba was in October of Zhejiang province. The result of correlation analysis with meteorological factors shows that the temperature and precipitation have non-significant effect on the main components of G. biloba. In addition, the type and content (Mn and Zn) of the soil showed significantly effect on the content of flavonoids and terpene lactones. This study enriched the knowledge on the development and utilization value of the G. biloba leaves and was useful for determining the optimal harvest time and growing condition.

[The effects of stelleta ganglion resection on heart failure in response to pressure overload]

Objective: To observe the impact and difference of resection of left stellate ganglion (LSG) or right stellate ganglion (RSG) on rats with heart failure. Methods: Thirty male SD rats were divided into 3 groups (n=10 each) by random number table method: control group, LSG group, RSG group. All three groups underwent TAC surgery to establish a pressure-overloaded heart failure model. Then, LSG and RSG were bluntly separated and removed in rats assigned to the LSG group or RSG group by surgery, while rats in the control group underwent sham operation. The changes in blood pressure and heart rate before operation, 30 minutes and 10 weeks after operation were recorded; echocardiography was performed before operation and 10 weeks after operation to detect the thickness of the ventricular septum, left ventricle posterior wall diameter, left ventricular end diastolic diameter, left ventricular end diastolic volume, and calculate the left ventricular fractional shortening and left ventricular ejection fraction. HE staining and Masson staining were performed to observe the degree of myocardial hypertrophy and myocardial fibrosis, and to judge the ventricular remodeling. Results: The heart rates of the three groups of rats were (352.4±4.3), (320.3±4.0) and (297.9±5.9) beats/min, and the blood pressure was (142.8±2.3), (123.4±2.7) and (129.6±2.9) mmHg(1 mmHg=0.133 kPa) at thirty minutes after surgery; the heart rates of the three groups of rats were (352.9±4.0), (321.6±3.4) and (301±4.1) beats/min, and the blood pressure was (145.6±1.9), (124.8±1.7) and (130.4±4.4) mmHg at 10 weeks after surgery. The heart rate and blood pressure in the LSG group and RSG group at 30 min and 10 weeks after surgery were significantly lower than those in the control group; at 10 weeks after surgery, the heart rate in the RSG group was significantly lower than that in the LSG group (P both<0.001). After 10 weeks, rats in the control group developed severe left ventricular dilatation. Degree of left ventricular hypertrophy was significantly reduced in the LSG group and RSG group than in the control group, the thickness of the ventricular septum was (3.2±0.3), (2.5±0.1) and (2.5±0.1) mm; the left ventricular end-diastolic diameters were (7.5±0.3), (5.5±0.3) and (5.7±0.2) mm; the left ventricular end-diastolic volume was (9.5±0.3), (4.5±0.2) and (4.8±0.2) ml; the left ventricular fractional shortening was (21.6±1.3)%, (49.1±3.9)% and (47.4±1.5)%; and the left ventricular ejection fraction was (50.9±2.5)%, (81.9±2.1)% and (80.0±2.3)%, respectively in the control group, LSG group and RSG group. Compared with the control group, the left ventricular posterior wall diameter, left ventricular end-diastolic diameter and left ventricular end-diastolic volume were significantly lower and the left ventricular fractional shortening and left ventricular ejection fraction were significantly higher in the LSG group and RSG group (all P<0.001). 10 weeks after operation, the values of type Ⅰ collagen in the control group, LSG group, and RSG group were (0.354±0.013), (0.211±0.012) and (0.243±0.013), respectively. Ratio of type Ⅰ/Ⅲ collagen was (1.109±0.065), (0.737±0.055) and (0.839±0.075), respectively. Compared with the control group, the ratio of type Ⅰcollagen and ratio of type Ⅰ/Ⅲ collagen were significantly lower in the LSG group and RSG group (P<0.001). Conclusion: Both left and right stellate ganglion resection can similarly reduce ventricular remodeling caused by pressure overload and delay the progression of heart failure in tis TAC rat model.

Comparison of three different types of splints and templates for maxilla repositioning in bimaxillary orthognathic surgery: a randomized controlled trial

The selection and implementation of a plan for maxillary surgery is of the utmost importance in achieving the desired outcome for the patient undergoing two-jaw orthognathic surgery. Some splint-based and splintless methods, accompanied by computer-assisted techniques, are helpful in improving surgical plan implementation. However, randomized controlled trials focused on this procedure are lacking. This study included 61 patients who underwent bimaxillary surgeries. The patients were randomly assigned to a conventional resin occlusal splint (CROS) group, a digital occlusal splint (DOS) group, or a digital templates (DT) group, in a 1:1:1 ratio. The mean linear distance between the planned and actual postoperative positions of eight selected points on the surfaces of the maxillary teeth was selected as the outcome measure. The distance was significantly smaller in the DT group (1.17±0.66mm) when compared to both the CROS group (2.55±0.95mm, P<0.05) and DOS group (2.15±1.12mm, P<0.05). However, the difference between the CROS group and DOS group was not statistically significant. These findings indicate that using digital templates results in the best performance in transferring the surgical plan to the operation environment as compared to the other two types of splints. This suggests that the application of digital templates could provide a reliable treatment option.

Risk factors for bad splits during sagittal split ramus osteotomy: a retrospective study of 964 cases

To identify the potential risk factors for bad splits, we calculated the incidence of bad splits from 484 patients with 964 cases of sagittal split ramus osteotomy (SSRO) and investigated the association between the occurrence of bad splits and risk factors such as gender, patients' age, class of occlusion, unimaxillary or bimaxillary surgery, presence of the lower third molar, thickness of the ascending ramus, and the distance from the mandibular canal to the buccal cortical bone. The results showed that 40 sides (4.149%) with bad splits occurred in 36 patients (7.438%). The mean (SD) gap width from the canal to the buccal cortex for the bad split group, at 4.02 (1.20)mm, was narrower (p=0.003; OR=0.689; 95% CI=0.538 to 0.882) than the normal split group 4.80 (1.72)mm. On the contrary, no statistical significance (p>0.05) was detected between the patients with bad splits and those with normal splits for the other factors. In conclusion, SSRO patients with narrower distances from the mandibular canal to the buccal cortex were more prone to bad splits. More attention should be paid to patients with this risk factor during future surgeries.

Bedaquiline in the treatment of multidrug- and extensively drug-resistant tuberculosis in China

BACKGROUND: Multidrug- and extensively drug-resistant tuberculosis (MDR/XDR-TB) continues to be a challenge in China. Bedaquiline (BDQ) is associated with accelerated sputum culture conversion and favourable treatment outcomes when added to a preferred background regimen. This post-hoc study aimed to assess the outcomes of BDQ treatment in Chinese patients with MDR/XDR-TB.METHODS: Data from 51 Chinese patients who participated in a global Phase 2, open-label, single-arm study (TMC207-C209) were analysed for effectiveness and safety of the BDQ-containing regimen.RESULTS: During the 24-week BDQ treatment, adverse events (AEs) occurred in 48 patients (94.1%), with the most common AE being hyperuricemia. Drug-induced liver injury (DILI) was reported in 13 patients (25.5%); serious DILI was reported in one patient (2.0%). Seven (13.7%) AEs were considered to be possibly related to BDQ by the investigators. Only one Grade 1 QTc prolongation was reported; no QTcF >500 ms was reported. One death occurred after BDQ treatment due to progressive TB. The median time to sputum culture conversion was 85 days based on the 24-week data. The sputum culture conversion rate was 82% at 24 weeks and 78% at 120 weeks; 66% of patients achieved a cure.CONCLUSIONS: BDQ was well-tolerated and effective for treating MDR-TB among Chinese patients.

Radiomics for precision medicine: Current challenges, future prospects, and the proposal of a new framework

The advancement of artificial intelligence concurrent with the development of medical imaging techniques provided a unique opportunity to turn medical imaging from mostly qualitative, to further quantitative and mineable data that can be explored for the development of clinical decision support systems (cDSS). Radiomics, a method for the high throughput extraction of hand-crafted features from medical images, and deep learning -the data driven modeling techniques based on the principles of simplified brain neuron interactions, are the most researched quantitative imaging techniques. Many studies reported on the potential of such techniques in the context of cDSS. Such techniques could be highly appealing due to the reuse of existing data, automation of clinical workflows, minimal invasiveness, three-dimensional volumetric characterization, and the promise of high accuracy and reproducibility of results and cost-effectiveness. Nevertheless, there are several challenges that quantitative imaging techniques face, and need to be addressed before the translation to clinical use. These challenges include, but are not limited to, the explainability of the models, the reproducibility of the quantitative imaging features, and their sensitivity to variations in image acquisition and reconstruction parameters. In this narrative review, we report on the status of quantitative medical image analysis using radiomics and deep learning, the challenges the field is facing, propose a framework for robust radiomics analysis, and discuss future prospects.

Multiple-centre clinical evaluation of an ultrafast single-tube assay for SARS-CoV-2 RNA

OBJECTIVE

To evaluate the performance of an ultrafast single-tube nucleic acid isothermal amplification detection assay for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA using clinical samples from multiple centres.

METHODS

A reverse transcription recombinase-aided amplification (RT-RAA) assay for SARS-CoV-2 was conducted within 15 minutes at 39°C with portable instruments after addition of extracted RNA. The clinical performance of RT-RAA assay was evaluated using 947 clinical samples from five institutions in four regions of China; approved commercial fluorescence quantitative real-time PCR (qRT-PCR) kits were used for parallel detection. The sensitivity and specificity of RT-RAA were compared and analysed.

RESULTS

The RT-RAA test results of 926 samples were consistent with those of qRT-PCR (330 were positive, 596 negative); 21 results were inconsistent. The sensitivity and specificity of RT-RAA was 97.63% (330/338, 95% confidence interval (CI) 95.21 to 98.90) and 97.87% (596/609, 95% CI 96.28 to 98.81) respectively. The positive and negative predictive values were 96.21% (330/343, 95% CI 93.45 to 97.88) and 98.68% (596/604, 95% CI 97.30 to 99.38) respectively. The total coincidence rate was 97.78% (926/947, 95% CI 96.80 to 98.70), and the kappa was 0.952 (p < 0.05).

CONCLUSIONS

With comparable sensitivity and specificity to the commercial qRT-PCR kits, RT-RAA assay for SARS-CoV-2 exhibited the distinctive advantages of simplicity and rapidity in terms of operation and turnaround time.

Peritonitis in Continuous Ambulatory Peritoneal Dialysis {CAPD): A Multi-Centre Randomized Clinical Trial Comparing the Y Connector Disinfectant System to Standard Systems

sixty-one new continuous ambulatory peritoneal dialysis (CAPD) patients were allocated to a Y connector disinfectant (Amuchina, Italy) and 63 to standard systems (Baxter Systems II & III) in a randomized clinical trial addressing peritonitis rates in 8 CAPD programs in 6 Canadian cities. In the Y connector-disinfectant group, 15 patients experienced 21 episodes of peritonitis in 452 patient-months or 1 per 21.53 patient-months. In the standard systems group, 30 patients experienced 47 episodes of peritonitis in 467 patient-months or 1 per 9.93 patient-months ( p = 0.009). The peritonitis risk reduction was 61% (95% confidence limits 27–79%). Exit-site infections occurred in 36% of each group.

Prior to the development of exit -site infection, the monthly risk for peritonitis was 3.12% for the Y connector disinfectant system and 7.37% for the standard system. After an exit -site infection, these probabilities increased to 6.15% and 15.47%, respectively. Skin organisms were responsible for peritonitis in 8/21 (38%) in the Y connector-disinfectant group and 30/47 (64%) in the standard group. There were 75 days hospitalized for peritonitis in the Y connector-disinfectant group compared to 257 days for the standard group. The Y connector disinfectant system decreases the peritonitis rate through its effect on skin organisms. Exit -site infections are a major source of organisms responsible for peritonitis.

Peritonitis in Continuous Ambulatory Peritoneal Dialysis (CAPD) Patients: A Randomized Clinical Trial of Cotrimoxazole Prophylaxis

A double-blind randomized controlled trial compared the effectiveness of prophylactic oral trimethoprim/sulfamethoxazole (cotrimoxazole) to a placebo in preventing peritonitis in continuous ambulatory peritoneal dialysis (CAPD) patients. A daily trimethoprim/sulfamethoxazole dose of 160/800 mg gives a steady state dialysate concentration of 1.07/4.35 mg/L in the final dwell of each dosing interval. Identification of a 40% reduction in peritonitis probability with 80% statistical power and a type 1 error probability of 0.05 required 52 subjects per group. With stratification by previous peritonitis, 56 were allocated to cotrimoxazole and 49 to placebo. For cotrimoxazole there were five deaths and seven catheter losses. For placebo there were three deaths and nine catheter losses. There were 20 withdrawals from cotrimoxazole and 9 from the placebo group. With respect to time to peritonitis, there was no statistically significant difference between cotrimoxazole and placebo groups (p = 0.19). At 6 months, 64.1% of cotrimoxazole and 62.5% of placebo were peritonitis free; at 12 months 41.9% of cotrimoxazole and 35% of placebo were peritonitis free. There was no effect (p > 0.05) of age, sex, catheter care technique, spike or luer, or dialysate additives. Previous peritonitis increased the risk of peritonitis by 2.06 (95% CI, 3.61–1.18) while frequent (six weekly) extension tubing changes increased the risk of by 1.79, (95% CI, 3.04–1.02) when compared to six monthly changes. Cotrimoxazole appears ineffective in prevention of CAPD peritonitis.

The transport of liquids in softwood: timber as a model porous medium

Timber is the only widely used construction material we can grow. The wood from which it comes has evolved to provide structural support for the tree and to act as a conduit for fluid flow. These flow paths are crucial for engineers to exploit the full potential of timber, by allowing impregnation with liquids that modify the properties or resilience of this natural material. Accurately predicting the transport of these liquids enables more efficient industrial timber treatment processes to be developed, thereby extending the scope to use this sustainable construction material; moreover, it is of fundamental scientific value - as a fluid flow within a natural porous medium. Both structural and transport properties of wood depend on its micro-structure but, while a substantial body of research relates the structural performance of wood to its detailed architecture, no such knowledge exists for the transport properties. We present a model, based on increasingly refined geometric parameters, that accurately predicts the time-dependent ingress of liquids within softwood timber, thereby addressing this long-standing scientific challenge. Moreover, we show that for the minimalistic parameterisation the model predicts ingress with a square-root-of-time behaviour. However, experimental data show a potentially significant departure from this [Formula: see text] behaviour - a departure which is successfully predicted by our more advanced parametrisation. Our parameterisation of the timber microstructure was informed by computed tomographic measurements; model predictions were validated by comparison with experimental data. We show that accurate predictions require statistical representation of the variability in the timber pore space. The collapse of our dimensionless experimental data demonstrates clear potential for our results to be up-scaled to industrial treatment processes.

[Survival time and influencing factors in multidrug-resistant tuberculosis patients in Wuhan, 2006-2014]

Objective: To investigate the survival time of multidrug-resistant tuberculosis (MDR-TB) patients and the influential factors in Wuhan. Methods: The relevant information were collected from TB management information system, cause of death reporting system and medical records by trained doctors. The univariate and multivariate Cox proportional hazards model were applied to analyze the factors affecting survival time of patients. Results: A total of 552 patients with MDR-TB were included in the analysis. After the diagnosis of MDR-TB, the cumulative survival rates from the first year to the third year were 0.94, 0.88, and 0.80, respectively. The mortality density of MDR-TB patients was 6.52/100 person-years, and the median survival time was (89.52±1.85) months. Kaplan-Meier analysis showed that the cumulative survival rate of the standardized treatment group was significantly higher than that of the non-standardized treatment group (Log rank=101.070, P<0.001). Compared with the patients aged <30 years, the HR of the patients aged 30-years and ≥60 years were 2.987 (95%CI: 1.268-7.036), 4.957 (95%CI: 1.942-12.653). Compared with the patients with the education level of high school and above, the HR of the patients with education level of junior high school/primary school and below were 1.908 (95%CI: 1.152-3.160), 1.681(95%CI: 1.033-2.735). Compared with the patients without diabetes, the HR of the patients with diabetes was 1.961(95%CI: 1.347-2.854). Compared with the patients without other serious diseases, the HR of the patients with other serious diseases was 2.597 (95%CI: 1.820-3.706). Compared with the patients who had been treated less than one time, the HR of the patients having previous treatment with more than 2 times was 1.611 (95%CI: 1.077-2.409). Compared with patients receiving standard MDR regimen treatment, the HR of the patients receiving no standard MDR regimen treatment was 3.155 (95%CI: 2.132-4.670). Conclusions: The cumulative survival rate of MDR-TB patients without standard treatment was significantly lower than that of patients with standard treatment. Older age, low educational level, diabetes mellitus, other serious diseases, more than two times treatment in the past, and receiving no multi-drug resistance regimen treatment were the risk factors affecting the survival of MDR-TB patients.

Fine-tuning the photosynthetic light harvesting apparatus for improved photosynthetic efficiency and biomass yield

Photosynthetic electron transport rates in higher plants and green algae are light-saturated at approximately one quarter of full sunlight intensity. This is due to the large optical cross section of plant light harvesting antenna complexes which capture photons at a rate nearly 10-fold faster than the rate-limiting step in electron transport. As a result, 75% of the light captured at full sunlight intensities is reradiated as heat or fluorescence. Previously, it has been demonstrated that reductions in the optical cross-section of the light-harvesting antenna can lead to substantial improvements in algal photosynthetic rates and biomass yield. By surveying a range of light harvesting antenna sizes achieved by reduction in chlorophyll b levels, we have determined that there is an optimal light-harvesting antenna size that results in the greatest whole plant photosynthetic performance. We also uncover a sharp transition point where further reductions or increases in antenna size reduce photosynthetic efficiency, tolerance to light stress, and impact thylakoid membrane architecture. Plants with optimized antenna sizes are shown to perform well not only in controlled greenhouse conditions, but also in the field achieving a 40% increase in biomass yield.