[Clinical features of post-neurosurgical bacterial meningitis in children]

Objective: To understand the characteristics of bacterial meningitis after pediatric neurosurgical procedures. Methods: This was a retrospective observational study. From January 2016 to December 2022, 64 children diagnosed with post-neurosurgical bacterial meningitis based on positive cerebrospinal fluid (CSF) culture in Department of Neurosurgery of Shanghai Children's Medical Center were selected as the study population. The clinical characteristics, onset time, routine biochemical indexes of cerebrospinal fluid before anti infection treatment, bacteriology characteristics and sensitivity to antibiotics of bacteria cultured from cerebrospinal fluid were analyzed. Based on the CSF culture results, the patients were divided into the Gram-positive bacteria infection group and the Gram-negative bacteria infection group. The clinical characteristics of the two groups were compared using t-tests or Wilcoxon rank-sum tests, and chi-square tests. Results: There were 64 children,42 boys and 22 girls, with onset age of 0.83 (0.50, 1.75) years. Seventy cases of post-neurosurgical bacterial meningitis occurred in the 64 children, of which 15 cases (21%) in spring, 23 cases (33%) in summer, 19 cases (27%) in autumn, and 13 cases (19%) in winter. The time of onset was 3.5 (1.0, 10.0) months after surgery; 15 cases (21%) occurred within the first month after the surgery, and 55 cases (79%) occurred after the first month. There were 38 cases (59%) showing obvious abnormal clinical manifestations, fever 36 cases (56%), vomiting 11 cases (17%). Forty-eight cases (69%) were caused by Gram-positive bacteria, with Staphylococcus epidermidis 24 cases; 22 cases (31%) were caused by Gram-negative bacteria, with Acinetobacter baumannii the prominent pathogen 7 cases. The Gram-positive bacterial infection was more common in summer than the Gram-negative bacterial infection (20 cases (42%) vs. 3 cases (14%), χ²=5.37, P=0.020), while the Gram-negative bacterial infection was more in autumn and within the first month after surgery than the Gram-positive bacterial infection (11 cases (50%) vs. 8 cases (17%), 15 cases (67%) vs. 5 cases (33%), χ²=8.48, 9.02; P=0.004, 0.003). Gram-positive bacteria resistant to vancomycin and Acinetobacter baumannii resistant to polymyxin were not found. However, Acinetobacter baumannii showed only 45% (10/22) susceptibility to carbapenem antibiotics. Conclusions: The clinical presentation of post-neurosurgical bacterial meningitis in children is atypical. Gram-positive bacteria are the main pathogens causing post-neurosurgical bacterial meningitis; Gram-negative bacterial meningitis are more likely to occur in autumn and within the first month after surgery. Acinetobacter baumannii has a high resistance rate to carbapenem antibiotics, which should be taken seriously.

[Application of periodontal regeneration strategy by treating both symptoms and primary cause in natural tooth preservation]

Teeth with severe periodontitis always have occlusal trauma, local anatomical abnormalities, mucogingival deformities or other factors that aggravate plaque retention or periodontal tissue damage. For these teeth, the author put forward the strategy of treating both symptoms and primary cause. That is, carrying out the periodontal regeneration surgery on the basis of analyzing and removing the primary cause factors. Through literature review and case series analysis, this paper discusses the therapeutic effects of strategy by treating both symptoms and primary cause on teeth with severe periodontitis, in order to provide reference for clinician work.

[Feasibility of a single-port thoracoscopy-assisted five-step laparoscopic procedure via transabdominal diaphragmatic approach for No.111 lymphadenectomy in patients with Siewert type II esophageal gastric junction adenocarcinoma]

Objective: We aimed to explore the feasibility of a single-port thoracoscopy- assisted five-step laparoscopic procedure via transabdominal diaphragmatic(TD) approach(abbreviated as five-step maneuver) for No.111 lymphadenectomy in patients with Siewert type II esophageal gastric junction adenocarcinoma (AEG). Methods: This was a descriptive case series study. The inclusion criteria were as follows: (1) age 18-80 years; (2) diagnosis of Siewert type II AEG; (3) clinical tumor stage cT2-4aNanyM0; (4) meeting indications of the transthoracic single-port assisted laparoscopic five-step procedure incorporating lower mediastinal lymph node dissection via a TD approach; (5) Eastern Cooperative Oncology Group performance status (ECOG PS) 0-1; and (6) American Society of Anesthesiologists classification I, II, or III. The exclusion criteria included previous esophageal or gastric surgery, other cancers within the previous 5 years, pregnancy or lactation, and serious medical conditions. We retrospectively collected and analyzed the clinical data of 17 patients (age [mean ± SD], [63.6±11.9] years; and 12 men) who met the inclusion criteria in the Guangdong Provincial Hospital of Chinese Medicine from January 2022 to September 2022. No.111 lymphadenectomy was performed using five-step maneuver as follows: superior to the diaphragm, starting caudad to the pericardium, along the direction of the cardio-phrenic angle and ending at the upper part of the cardio-phrenic angle, right to the right pleura and left to the fibrous pericardium , completely exposing the cardio-phrenic angle. The primary outcome includes the numbers of harvested and of positive No.111 lymph nodes. Results: Seventeen patients (3 proximal gastrectomy and 14 total gastrectomy) had undergone the five-step maneuver including lower mediastinal lymphadenectomy without conversion to laparotomy or thoracotomy and all had achieved R0 resection with no perioperative deaths. The total operative time was (268.2±32.9) minutes, and the lower mediastinal lymph node dissection time was (34.0±6.0) minutes. The median estimated blood loss was 50 (20-350) ml. A median of 7 (2-17) mediastinal lymph nodes and 2(0-6) No. 111 lymph nodes were harvested. No. 111 lymph node metastasis was identified in 1 patient. The time to first flatus occurred 3 (2-4) days postoperatively and thoracic drainage was used for 7 (4-15) days. The median postoperative hospital stay was 9 (6-16) days. One patient had a chylous fistula that resolved with conservative treatment. No serious complications occurred in any patient. Conclusion: The single-port thoracoscopy-assisted five-step laparoscopic procedure via a TD approach can facilitate No. 111 lymphadenectomy with few complications.

[A multicenter epidemiological study of acute bacterial meningitis in children]

Objective: To analyze the clinical epidemiological characteristics including composition of pathogens , clinical characteristics, and disease prognosis acute bacterial meningitis (ABM) in Chinese children. Methods: A retrospective analysis was performed on the clinical and laboratory data of 1 610 children <15 years of age with ABM in 33 tertiary hospitals in China from January 2019 to December 2020. Patients were divided into different groups according to age,<28 days group, 28 days to <3 months group, 3 months to <1 year group, 1-<5 years of age group, 5-<15 years of age group; etiology confirmed group and clinically diagnosed group according to etiology diagnosis. Non-numeric variables were analyzed with the Chi-square test or Fisher's exact test, while non-normal distrituction numeric variables were compared with nonparametric test. Results: Among 1 610 children with ABM, 955 were male and 650 were female (5 cases were not provided with gender information), and the age of onset was 1.5 (0.5, 5.5) months. There were 588 cases age from <28 days, 462 cases age from 28 days to <3 months, 302 cases age from 3 months to <1 year of age group, 156 cases in the 1-<5 years of age and 101 cases in the 5-<15 years of age. The detection rates were 38.8% (95/245) and 31.5% (70/222) of Escherichia coli and 27.8% (68/245) and 35.1% (78/222) of Streptococcus agalactiae in infants younger than 28 days of age and 28 days to 3 months of age; the detection rates of Streptococcus pneumonia, Escherichia coli, and Streptococcus agalactiae were 34.3% (61/178), 14.0% (25/178) and 13.5% (24/178) in the 3 months of age to <1 year of age group; the dominant pathogens were Streptococcus pneumoniae and the detection rate were 67.9% (74/109) and 44.4% (16/36) in the 1-<5 years of age and 5-<15 years of age . There were 9.7% (19/195) strains of Escherichia coli producing ultra-broad-spectrum β-lactamases. The positive rates of cerebrospinal fluid (CSF) culture and blood culture were 32.2% (515/1 598) and 25.0% (400/1 598), while 38.2% (126/330)and 25.3% (21/83) in CSF metagenomics next generation sequencing and Streptococcus pneumoniae antigen detection. There were 4.3% (32/790) cases of which CSF white blood cell counts were normal in etiology confirmed group. Among 1 610 children with ABM, main intracranial imaging complications were subdural effusion and (or) empyema in 349 cases (21.7%), hydrocephalus in 233 cases (14.5%), brain abscess in 178 cases (11.1%), and other cerebrovascular diseases, including encephalomalacia, cerebral infarction, and encephalatrophy, in 174 cases (10.8%). Among the 166 cases (10.3%) with unfavorable outcome, 32 cases (2.0%) died among whom 24 cases died before 1 year of age, and 37 cases (2.3%) had recurrence among whom 25 cases had recurrence within 3 weeks. The incidences of subdural effusion and (or) empyema, brain abscess and ependymitis in the etiology confirmed group were significantly higher than those in the clinically diagnosed group (26.2% (207/790) vs. 17.3% (142/820), 13.0% (103/790) vs. 9.1% (75/820), 4.6% (36/790) vs. 2.7% (22/820), χ²=18.71, 6.20, 4.07, all P<0.05), but there was no significant difference in the unfavorable outcomes, mortility, and recurrence between these 2 groups (all P>0.05). Conclusions: The onset age of ABM in children is usually within 1 year of age, especially <3 months. The common pathogens in infants <3 months of age are Escherichia coli and Streptococcus agalactiae, and the dominant pathogen in infant ≥3 months is Streptococcus pneumoniae. Subdural effusion and (or) empyema and hydrocephalus are common complications. ABM should not be excluded even if CSF white blood cell counts is within normal range. Standardized bacteriological examination should be paid more attention to increase the pathogenic detection rate. Non-culture CSF detection methods may facilitate the pathogenic diagnosis.

[Reliability and validity of the Chinese version of the test of the adherence to inhalers (TAI)]

Objectives: To evaluate the reliability and validity of the Chinese version of the test of the adherence to inhalers (TAI) in Chinese patients with chronic airway disease. Methods: Based on the English version of TAI, the items of the Chinese version of TAI were determined after forward-backward translation and cultural adaption. Totally, 165 patients with chronic obstructive pulmonary disease (COPD) and asthma were enrolled from Respiratory Clinic of the Second Xiangya Hospital of Central South University from July to November 2021, and a questionnaire survey was conducted using the Chinese version of TAI and the Morisky medication adherence scale 8-item version (MMAS-8). The content validity of the scale was expressed by content validity index (CVI) and the construct validity was analyzed by exploratory factor analysis (EFA). The convergence validity was evaluated by Pearson correlation analysis. The reliability of the scale was expressed by Cronbach's α coefficient, the split-half reliability and test-retest reliability. Results: The CVI was 0.966. There were 10 items in total. Two factors were extracted from the Chinese version of TAI and the cumulative variance contribution rate was 57.236%. The load value of each item was more than 0.400 and the factor attribution of the item was consistent with the original scale. The total score of the Chinese version of TAI was positively correlated with the total score of the MMAS-8(r=0.835,P<0.001). The Cronbach's α of the overall scale was 0.843, the Guttman's half-reliability coefficient was 0.796 and the test-retest reliability was 0.884 (P<0.001), respectively. Conclusions: The Chinese version of TAI has good reliability and validity, which may be a reliable tool for evaluating the adherence to inhalers of patients with chronic airway disease in China.

[Safety and feasibility of intrathoracic modified overlap esophagojejunostomy in laparoscopic radical resection of Siewert type Ⅱ adenocarcinoma of esophagogastric junction]

Objective: The study aimed to investigate the safety and feasibility of intrathoracic modified overlap method in laparoscopic radical resection of Siewert type II adenocarcinoma of the esophagogastric junction (AEG). Methods: A descriptive case series study was conducted. The clinical data of 27 patients with Siewert type II AEG who underwent transthoracic single-port assisted laparoscopic total gastrectomy and intrathoracic modified overlap esophagojejunostomy in Guangdong Provincial Hospital of Chinese Medicine from May 2017 to December 2020 were retrospectively analyzed. The intrathoracic modified overlap esophagojejunostomy was performed as follows: (1) The Roux-en-Y loop was made; (2) The jejunum side was prepared extraperitoneal for overlap anastomosis; (3) The esophagus side was prepared intraperitoneal for overlap anastomosis; (4) The overlap esophagojejunostomy was performed; (5) The common outlet was closed after confirmation of anastomosis integrity without bleeding; (6) A thoracic drainage tube was inserted into the thoracic hole with the diaphragm incision closed. The intraoperative and postoperative results were reviewed. Results: All 27 patients were successfully operated, without mortality or conversion to laparotomy. The operative time, digestive tract reconstruction time and esophageal-jejunal anastomosis time were (327.5±102.0) minute, 50 (28-62) minute and (29.0±7.4) minute, respectively. The blood loss was 100 (20-150) ml. The postoperative time to flatus and postoperative hospital stay were (4.7±3.7) days and 9(6-73) days, respectively. Three patients (11.1%) developed postoperative grade III complications according to the Clavien-Dindo classification, including 1 case of anastomotic fistula with empyema, 1 case of pleural effusion and 1 case of pancreatic fistula, all of whom were cured by puncture drainage and anti-infective therapy. Conclusions: The intrathoracic modified overlap esophagojejunostomy is safe and feasible in laparoscopic radical resection of Siewert type II AEG.

[Five-step maneuver of transthoracic single-port assisted laparoscopic lower mediastinal lymph node dissection for Siewert type Ⅱ adenocarcinoma of the esophagogastric junction]

Objective: Surgical operation is the main treatment for advanced adenocarcinoma of esophagogastric junction (AEG). Due to its special anatomic location and unique lymph node reflux mode, the surgical treatment of Siewert II AEG is controversial. Lower mediastinal lymph node dissection is one of the most controversial points and a standard technique has not yet been established. This study is aim to explore the safety and feasibility of five-step maneuver of transthoracic single-port assisted laparoscopic lower mediastinal lymph node dissection for Siewert type II AEG. Methods: A descriptive case series study was conducted. The intraoperative and postoperative data of 25 patients with Siewert type II AEG who underwent five-step maneuver of transthoracic single-port assisted laparoscopic lower mediastinal lymph node dissection in Guangdong Provincial Hospital of Traditional Chinese Medicine from January 2019 to April 2021 were retrospectively analyzed. Five-step maneuver was as follows: In the first step, the subcardiac sac was exposed; the right pulmonary ligament lymph nodes and the anterior thoracic paraaortic lymph nodes were dissected cranial to inferior pericardium, left to left edge of thoracic aorta. In the second step, the left diaphragm was opened, and a 12 mm trocar was placed through the 6-7 rib in the left anterior axillary line. The supra-diaphragmatic nodes were dissected through the thoracic operation hole. In the third step, the left inferior pulmonary ligament was severed. The anterior fascia of thoracic aorta was incised to join the anterior space of thoracic aorta formed in the first step and then the lymphatic tissue was dissected upward until the exposure of left inferior pulmonary vein. In the fourth step, the posterior pericardium was denuded retrogradely from ventral side to oral side to the level of left inferior pulmonary vein, right to right pleura, and then the right pulmonary ligament lymph nodes were completely removed. In the fifth step, the esophagus was denuded, and the esophagus was transected 5 cm above the tumor using a linear stapler to complete the dissection of lower thoracic paraesophageal lymph nodes. Results: Operations were successfully completed in 25 patients without conversion, intra-operative complication and perioperative death. Total gastrectomy was performed in 19 cases and proximal gastrectomy in 6 cases. The mean operative time was (268.7±85.6) minutes, the mean estimated blood loss was (90.4±44.2) ml, the mean time of lower mediastinal lymph node dissection was (38.6±10.3) minutes, and the mean harvested number of lower mediastinal lymph node was 5.9±2.9. The length of esophageal invasion was >2 cm in 7 cases and ≤ 2 cm in 18 cases. Eight patients (33.0%) had lower mediastinal lymph node metastasis, including 3 cases with esophageal invasion >2 cm and 5 cases with esophageal invasion ≤ 2 cm. The mean time to postoperative first flatus was (5.5±3.1) days. The average time of postoperative thoracic drainage was (5.9±2.9) days. The mean hospital stay was (9.7±3.1) days. Two patients (8.0%) developed postoperative grade IIIa complications according to the Clavien-Dindo classification, including 1 case of pancreatic fistula and 1 case of pleural effusion, both of whom were cured by puncture drainage. Conclusions: Five-step maneuver of transthoracic single-port assisted laparoscopic lower mediastinal lymph nodes dissection for Siewert type II AEG is safe and feasible. Which can ensure sufficient lower mediastinal lymph node dissection to the level of left inferior pulmonary vein.

[Efficacy observation of the caudal-medial approach combined with "page-turning" middle lymphadenectomy in the laparoscopic right hemicolectomy]

Objective: To investigate the safety and feasibility of caudal-medial approach combined with "page-turning" middle lymphadenectomy in the laparoscopic right hemicolectomy. Methods: A descriptive cohort study was conducted. Clinical data of 35 patients who underwent laparoscopic radical right hemicolectomy using caudal-medial approach combined with "page-turning" middle lymphadenectomy at Department of Gastrointestinal Surgery, Guangdong Hospital of Chinese Medicine from April 2018 to May 2020 were retrospectively analyzed. All operations were performed consecutively by the same surgeon. The caudal-medial approach was used to dissect the right Toldt's fascia and the anterior pancreaticoduodenal space in a caudal-to-cranial and medial-to-lateral manner guided by the duodenum. The "page-turning" middle lymphadenectomy was used to dissect the mesocolon along the superior mesenteric vein with ileocolic vein, Henle's trunk and pancreas exposed preferentially. Results: All the 35 patients completed the operation successfully, and there was no damage and bleeding of superior mesenteric vessels and their branches. The operative time was (186.9±46.2) minutes, and the blood loss was 50 (10-200) ml. The first time to flatus was (2.1±0.6) days, and the time to fluid intake was (2.5±0.8) days. The postoperative hospital stay was 6 (3-18) d. The overall morbidity of postoperative complication was 8.6% (3/35), including grade II in 1 cases (2.8%) and grade IIIa in 2 case (5.7%) according to the Clavien-Dindo grading standard. The total number of lymph node dissected was 30.2±5.6, and the positive lymph node was 0 (0-7). Tumor staging revealed 5 cases of stage I, 18 cases of stage II, 11 cases of stage III, and 1 case of stage IVA. In this study, the median follow-up time was 15 (4-29) months. One patient died due to cerebrovascular accident 12 months after surgery, and no tumor recurrence or metastasis was observed in all other patients. Conclusions: Laparoscopic radical right hemicolectomy using caudal-medial approach combined with "page-turning" middle lymphadenectomy is safe and feasible. The anterior pancreaticoduodenal space is preferentially mobilized, which reduces the difficulty of central vascular dissection.

Breeding for water-saving and drought-resistance rice (WDR) in China

Rice is the staple food and rice production consumes about 50% of the fresh water resources in China. In addition, drought is one of the most important constraints in rice resulting in large yield losses and limiting the average yield increase of the country. There is an urgent need to enhance water-saving (W) capacity or drought resistance (DR) of rice. WDR varieties can be developed through introgressing the water-saving and drought resistance capacity mainly from the traditional upland to the commercialized paddy rice cultivars. The breeding target is a high yield potential under irrigation, an acceptable grain quality, and water consumption reduced by about 50% compared with paddy rice. In a water-limited environment, a higher level of drought resistance and reduced yield loss by drought stress are required. In recent years, the field drought-resistance screening facility was established and the evaluation standard was developed. Some DR rice varieties were identified and used in both molecular mapping and breeding programmes. Several WDR varieties were developed and released to farmers. This article describes our initial achievement towards this goal and provides some details on the rationale and the specific steps and methods used.

Genetic basis of 17 traits and viscosity parameters characterizing the eating and cooking quality of rice grain

A recombinant inbred line population derived from a cross between Zhenshan 97 and Delong 208 was used to analyze the genetic basis of the cooking and eating quality of rice as reflected by 17 traits (or parameters). These traits include amylose content (AC), gel consistency (GC), alkali spreading value (ASV), cooked rice elongation (CRE), and 13 parameters from the viscosity profile. All the traits, except peak paste viscosity (PKV), time needed from gelatinization to peak (BAtime), and CRE, can be divided into two classes according to their interrelationship. The first class consists of AC, GC, and most of the paste viscosity parameters that form a major determinant of eating quality. The second class includes ASV, pasting temperature (Atemp) and pasting time (Atime), which characterize cooking process. We identified 26 QTL (quantitative trait locus or loci) in 2 years; nine QTL clusters emerged. The two major clusters, which correspond to the Wx and Alk loci, control the traits in the first and second classes, respectively. Some QTL are co-located for the traits belonging to the same class and also for the traits to a different class. The Wx locus also affects on ASV while the Alk locus also makes minor contributions to GC and some paste viscosity parameters. The QTL clusters on other chromosomes are similar to the Wx locus or Alk locus, although the variations they explained are relatively minor. QTL for CRE and PKV are dispersed and independent of the Wx locus. Low paste viscosity corresponds to low AC and soft gel, which represents good eating quality for most Chinese consumers; high ASV and low Atemp, together with reduced time to gelatinization and PKV, indicate preferred cooking quality. The genetic basis of Atemp, Atime, BAtime, peak temperature, peak time, paste viscosity at 95 degrees C, and final paste viscosity is newly examined to reveal a complete and dynamic viscosity profile.

QTLs influencing panicle size detected in two reciprocal introgressive line (IL) populations in rice (Oryza sativa L.)

Two sets of reciprocal introgression line (IL) populations, i.e., ILs with Lemont as recurrent parent (IL_LT) and ILs with Teqing as recurrent parent (IL_TQ), were developed and evaluated for traits representing panicle size, including primary branch number (PBN), secondary branch number (SBN), and spikelet number per panicle (SNP). Together with the regression to recurrent parent by advanced backcross, transgressive segregations were observed for all traits. Correlation and regression analysis showed that SBN had much higher contribution to SNP than PBN. It was confirmed by the QTL analysis that many common loci were detected between SBN and SNP, in comparison with single common locus between PBN and SNP. One and three main effect QTLs (M-QTLs) were detected for PBN in IL_LT and IL_TQ, respectively. Six M-QTLs per trait per populations were associated with SBN and SNP. Less number and lower contribution of epistasis were detected in IL populations in comparison with mapping result from F2 or RI population. There were only four QTLs in fourteen loci (near 30%) commonly detected in both reciprocal IL populations implying the large impact of genetic background on QTLs expression.

Grain yield responses to moisture regimes in a rice population: association among traits and genetic markers

Drought is a major constraint to rice (Oryza sativa L.) production in rainfed and poorly irrigated environments. Identifying genomic regions influencing the response of yield and its components to water deficits will aid our understanding of the genetic mechanism of drought tolerance (DT) of rice and the development of DT varieties. Grain yield (GY) and its components of a recombinant inbred population developed from a lowland rice and an upland rice were investigated under different water levels in 2003 and 2004 in a rainout DT screening facility. Correlation and path analysis indicated that spikelet fertility (SF) was particularly important for grain yield with direct effect (P=0.60) under drought stress, while spikelet number per panicle (SN) contributed the most to grain yield (P=0.41) under well-watered condition. A total of 32 quantitative trait loci (QTLs) for grain yield and its components were identified. The phenotypic variation explained by individual QTLs varied from 1.29% to 14.76%. Several main effect QTLs affecting SF, 1,000-grain weight (TGW), panicle number (PN), and SN were mapped to the same regions on chromosome 4 and 8. These QTLs were detected consistently across 2 years and under both water levels in this study. Several digenic interactions among yield components were also detected. The identification of genomic regions associated with GY and its components under stress will be useful to improve drought tolerance of rice by marker-aided approaches.

The main effects, epistatic effects and environmental interactions of QTLs on the cooking and eating quality of rice in a doubled-haploid line population

Amylose content (AC), gel consistency (GC) and gelatinazation temperature (GT) are three important traits that influence the cooking and eating quality of rice. The objective of this study was to characterize the genetic components, including main-effect quantitative trait loci (QTLs), epistatic QTLs and QTL-by-environment interactions (QEs), that are involved in the control of these three traits. A population of doubled haploid (DH) lines derived from a cross between two indica varieties Zhenshan 97 and H94 was used, and data were collected from a field experiment conducted in two different environments. A genetic linkage map consisting of 218 simple sequence repeat (SSR) loci was constructed, and QTL analysis performed using QTLMAPPER 1.6: resolved the genetic components into main-effect QTLs, epistatic QTLs and QEs. The analysis detected a total of 12 main-effect QTLs for the three traits, with a QTL corresponding to the Wx locus showing a major effect on AC and GC, and a QTL corresponding to the Alk locus having a major effect on GT. Ten digenic interactions involving 19 loci were detected for the three traits, and six main-effect QTLs and two pairs of epistatic QTLs were involved in QEs. While the main-effect QTLs, especially the ones corresponding to known major loci, apparently played predominant roles in the genetic basis of the traits, under certain conditions epistatic effects and QEs also played important roles in controlling the traits. The implications of the findings for rice quality improvement are discussed.

Gene actions of QTLs affecting several agronomic traits resolved in a recombinant inbred rice population and two backcross populations

To understand the types of gene action controlling seven quantitative traits in rice, we carried out quantitative trait locus (QTL) mapping in order to distinguish between the main-effect QTLs (M-QTLs) and digenic epistatic QTLs (E-QTLs) responsible for the trait performance of 254 recombinant inbred lines (RILs) from rice varieties Lemont/Teqing and two backcross hybrid (BCF1) populations derived from these RILs. We identified 44 M-QTL and 95 E-QTL pairs in the RI and BCF1 populations as having significant effects on the mean values and mid-parental heterosis of heading date, plant height, flag leaf length, flag leaf width, panicle length, spikelet number and spikelet fertility. The E-QTLs detected collectively explained a larger portion of the total phenotypic variation than the M-QTLs in both the RI and BCF1 populations. In both BCF1 populations, over-dominant (or under-dominant) loci were more important than additive and complete or partially dominant loci for M-QTLs and E-QTL pairs, thereby supporting prior findings that overdominance resulting from epistatic loci are the primary genetic basis of inbreeding depression and heterosis in rice.

Gene actions of QTLs affecting several agronomic traits resolved in a recombinant inbred rice population and two testcross populations

To understand the types of gene action controlling seven quantitative traits in rice, QTL mapping was performed to dissect the main effect (M-QTLs) and digenic epistatic (E-QTLs) QTLs responsible for the trait performance of 254 recombinant inbred lines (RILs) of "Lemont/Teqing", and two testcross (TC) F(1) populations derived from these RILs. The correlation analyses reveal a general pattern, i.e. trait heritability in the RILs was negatively correlated to trait heterosis in the TC hybrids. A large number of M-QTLs and E-QTLs affecting seven traits, including heading date (HD), plant height (PH), flag leaf length (FLL), flag leaf width (FLW), panicle length (PL), spikelet number per panicle (SN) and spikelet fertility (SF), were identified and could be classified into two predominant groups, additive QTLs detected primarily in the RILs, and overdominant QTLs identified exclusively in the TC populations. There is little overlap between QTLs identified in the RILs and in the TC populations. This result implied that additive gene action is largely independent from non-additive gene action in the genetic control of quantitative traits of rice. The detected E-QTLs collectively explained a much greater portion of the total phenotypic variation than the M-QTLs, supporting prior findings that epistasis has played an important role in the genetic control of quantitative traits in rice. The implications of these results to the development of inbred and hybrid cultivars were discussed.

RFLP-facilitated investigation of the quantitative resistance of rice to brown planthopper ( Nilaparvata lugens)

Quantitative trait loci (QTLs), conferring quantitative resistance to rice brown planthopper (BPH), were investigated using 160 F(11) recombinant inbred lines (RILs) from the Lemont/Teqing cross, a complete RFLP map, and replicated phenotyping of seedbox inoculation. The paternal indica parent, Teqing, was more-resistant to BPH than the maternal japonica parent, Lemont. The RILs showed transgressive segregation for resistance to BPH. Seven main-effect QTLs and many epistatic QTL pairs were identified and mapped on the 12 rice chromosomes. Collectively, the main-effect and epistatic QTLs accounted for over 70% of the total variation in damage scores. Teqing has the resistance allele at four main-effect QTLs, and the Lemont allele resulted in resistance at the other three. Of the main-effect QTLs identified, QBphr5b was mapped to the vicinity of gl1, a major gene controlling leaf and stem pubescence. The Teqing allele controlling leaf and stem pubescence was associated with resistance, while the Lemont allele for glabrous stem and leaves was associated with susceptibility, indicating that this gene may have contributed to resistance through antixenosis. Similar to the reported BPH resistance genes, the other six detected main-effect QTLs were all mapped to regions where major disease resistance genes locate, suggesting they might have contributed either to antibiosis or tolerance. Our results indicated that marker-aided pyramiding of major resistance genes and QTLs should provide effective and stable control over this devastating pest.

Overdominant epistatic loci are the primary genetic basis of inbreeding depression and heterosis in rice. II. Grain yield components

The genetic basis underlying inbreeding depression and heterosis for three grain yield components of rice was investigated in five interrelated mapping populations using a complete RFLP linkage map, replicated phenotyping, and the mixed model approach. The populations included 254 F(10) recombinant inbred lines (RILs) derived from a cross between Lemont (japonica) and Teqing (indica), two backcross (BC) and two testcross populations derived from crosses between the RILs and the parents plus two testers (Zhong413 and IR64). For the yield components, the RILs showed significant inbreeding depression and hybrid breakdown, and the BC and testcross populations showed high levels of heterosis. The average performance of the BC or testcross hybrids was largely determined by heterosis. The inbreeding depression values of individual RILs were negatively associated with the heterosis measurements of the BC or testcross hybrids. We identified many epistatic QTL pairs and a few main-effect QTL responsible for >65% of the phenotypic variation of the yield components in each of the populations. Most epistasis occurred between complementary loci, suggesting that grain yield components were associated more with multilocus genotypes than with specific alleles at individual loci. Overdominance was also an important property of most loci associated with heterosis, particularly for panicles per plant and grains per panicle. Two independent groups of genes appeared to affect grain weight: one showing primarily nonadditive gene action explained 62.1% of the heterotic variation of the trait, and the other exhibiting only additive gene action accounted for 28.1% of the total trait variation of the F(1) mean values. We found no evidence suggesting that pseudo-overdominance from the repulsive linkage of completely or partially dominant QTL for yield components resulted in the overdominant QTL for grain yield. Pronounced overdominance resulting from epistasis expressed by multilocus genotypes appeared to explain the long-standing dilemma of how inbreeding depression could arise from overdominant genes.

Overdominant epistatic loci are the primary genetic basis of inbreeding depression and heterosis in rice. I. Biomass and grain yield

To understand the genetic basis of inbreeding depression and heterosis in rice, main-effect and epistatic QTL associated with inbreeding depression and heterosis for grain yield and biomass in five related rice mapping populations were investigated using a complete RFLP linkage map of 182 markers, replicated phenotyping experiments, and the mixed model approach. The mapping populations included 254 F(10) recombinant inbred lines derived from a cross between Lemont (japonica) and Teqing (indica) and two BC and two testcross hybrid populations derived from crosses between the RILs and their parents plus two testers (Zhong 413 and IR64). For both BY and GY, there was significant inbreeding depression detected in the RI population and a high level of heterosis in each of the BC and testcross hybrid populations. The mean performance of the BC or testcross hybrids was largely determined by their heterosis measurements. The hybrid breakdown (part of inbreeding depression) values of individual RILs were negatively associated with the heterosis measurements of their BC or testcross hybrids, indicating the partial genetic overlap of genes causing hybrid breakdown and heterosis in rice. A large number of epistatic QTL pairs and a few main-effect QTL were identified, which were responsible for >65% of the phenotypic variation of BY and GY in each of the populations with the former explaining a much greater portion of the variation. Two conclusions concerning the loci associated with inbreeding depression and heterosis in rice were reached from our results. First, most QTL associated with inbreeding depression and heterosis in rice appeared to be involved in epistasis. Second, most ( approximately 90%) QTL contributing to heterosis appeared to be overdominant. These observations tend to implicate epistasis and overdominance, rather than dominance, as the major genetic basis of heterosis in rice. The implications of our results in rice evolution and improvement are discussed.

[QTL dissection of panicle number per plant and spikelet number per panicle in rice (Oryza sativa L.)]

The genetic mechanism underlying panicle number per plant (PN), spikelet number per panicle (SNP) and its related traits in rice was analysed using 292 F13 RILs from the cross of Lemont/Teqing and a complete linkage map with 272 molecular markers. The RILs showed tremendous transgressive segregation for all traits studied. The weak negative correlation between PN and SNP was observed. Fifty-one QTLs and 45 epistatic QTL pairs affecting these traits were identified, collectively explaining over 60% of the total variation of individual traits. Almost all SNP-QTLs were attributable to one or more of its contributing components. Branching number traits had greater contributions to SNP than length traits, in which the first had twice as many QTLs mapped in the same or near regions with SNP as the latter. Only two PN-QTLs were mapped in the near regions with those of related traits of SNP, suggesting a reasonable recombination between PN and SNP would be available by marker-assisted selection (MAS). Some major QTLs including QPn4 for panicle number, QPbn3a, QPbn3b and QPbl4 for panicle branching and length would be of great value in MAS. It was discussed that a new high-yielding panicle type was resulted from reasonably deploying for QTLs of panicle traits by MAS.

Overdominant epistatic loci are the primary genetic basis of inbreeding depression and heterosis in rice. I. Biomass and grain yield

To understand the genetic basis of inbreeding depression and heterosis in rice, main-effect and epistatic QTL associated with inbreeding depression and heterosis for grain yield and biomass in five related rice mapping populations were investigated using a complete RFLP linkage map of 182 markers, replicated phenotyping experiments, and the mixed model approach. The mapping populations included 254 F(10) recombinant inbred lines derived from a cross between Lemont (japonica) and Teqing (indica) and two BC and two testcross hybrid populations derived from crosses between the RILs and their parents plus two testers (Zhong 413 and IR64). For both BY and GY, there was significant inbreeding depression detected in the RI population and a high level of heterosis in each of the BC and testcross hybrid populations. The mean performance of the BC or testcross hybrids was largely determined by their heterosis measurements. The hybrid breakdown (part of inbreeding depression) values of individual RILs were negatively associated with the heterosis measurements of their BC or testcross hybrids, indicating the partial genetic overlap of genes causing hybrid breakdown and heterosis in rice. A large number of epistatic QTL pairs and a few main-effect QTL were identified, which were responsible for >65% of the phenotypic variation of BY and GY in each of the populations with the former explaining a much greater portion of the variation. Two conclusions concerning the loci associated with inbreeding depression and heterosis in rice were reached from our results. First, most QTL associated with inbreeding depression and heterosis in rice appeared to be involved in epistasis. Second, most ( approximately 90%) QTL contributing to heterosis appeared to be overdominant. These observations tend to implicate epistasis and overdominance, rather than dominance, as the major genetic basis of heterosis in rice. The implications of our results in rice evolution and improvement are discussed.

Effects of cancer chemotherapy on the blood fibrinogen concentrations of cancer patients

Blood fibrinogen concentrations and glutamic-pyruvic transaminase activities of 66 adult cancer inpatients (aged 22 - 70 years) were determined both before and after one or two chemotherapy regimens. The percentage of hepatoma patients with abnormal blood fibrinogen levels (< 1.5 or > 6.0 g/l) was higher (64.3% of 14 patients) than that in other cancer categories (19.2% of 52 patients). The mean blood fibrinogen concentrations of male (3.5 g/l) and female (4.5 g/l) cancer patients were higher than those previously reported for healthy humans (2.8 and 2.9 g/l, respectively). After chemotherapy, blood fibrinogen concentrations decreased in patients whose primary tumours were surgically removed (from 4.8 to 3.2 g/l) but increased (from 3.0 to 4.8 g/l) in those who did not undergo surgery. Glutamic-pyruvic transaminase activities did not appear to be related to blood fibrinogen levels. We conclude that the increase in mean blood fibrinogen levels of cancer patients is probably related to tumour growth. Different mechanisms may operate in patients with hepatoma.

A "defeated" rice resistance gene acts as a QTL against a virulent strain of Xanthomonas oryzae pv. oryzae

The genetic components responsible for qualitative and quantitative resistance of rice plants to three strains (CR4, CXO8, and CR6) of Xanthomonas oryzae pv. oryzae (Xoo) were investigated using a set of 315 recombinant inbred lines (RILs) from the cross Lemont (japonica) x Teqing (indica) and a complete linkage map with 182 well distributed RFLP markers. We mapped a major gene (Xa4) and ten quantitative trait loci (QTLs) which were largely responsible for segregation of the resistance phenotype in the RILs. The Teqing allele at the Xa4 locus, Xa4T, acted as a dominant resistance gene against CR4 and CXO8. The breakdown of Xa4T-associated resistance mediated by the mutant allele at the avrXa4 locus in the virulent strain CR6 results from significant changes in both gene action (lose of dominance) and the magnitude of gene effect (approximately 50% reduction). Nevertheless, Xa4T still acted as a recessive QTL with a significant residual effect against CR6. The mutant alleles at the avrXa4 locus in CXO8 and CR6 that lead to a reduction in effect, or "breakdown", of Xa4T were apparently accompanied by corresponding penalties for their fitness. The quantitative component of resistance to Xoo in the RILs was largely due to a number of resistance QTLs. Most resistance QTLs mapped to genomic locations where major resistance genes and/or QTLs for resistance to Xoo, blast and sheath blight were identified in the same cross. Most QTLs showed consistent levels of resistance against all three Xoo strains. Our results suggest that a high level of durable resistance to Xoo may be achieved by the cumulative effects of multiple QTLs, including the residual effects of "defeated" major resistance genes.