Genetic dissection of Al tolerance QTLs in the maize genome by high density SNP scan

BACKGROUND

Aluminum (Al) toxicity is an important limitation to food security in tropical and subtropical regions. High Al saturation on acid soils limits root development, reducing water and nutrient uptake. In addition to naturally occurring acid soils, agricultural practices may decrease soil pH, leading to yield losses due to Al toxicity. Elucidating the genetic and molecular mechanisms underlying maize Al tolerance is expected to accelerate the development of Al-tolerant cultivars.

RESULTS

Five genomic regions were significantly associated with Al tolerance, using 54,455 SNP markers in a recombinant inbred line population derived from Cateto Al237. Candidate genes co-localized with Al tolerance QTLs were further investigated. Near-isogenic lines (NILs) developed for ZmMATE2 were as Al-sensitive as the recurrent line, indicating that this candidate gene was not responsible for the Al tolerance QTL on chromosome 5, qALT5. However, ZmNrat1, a maize homolog to OsNrat1, which encodes an Al(3+) specific transporter previously implicated in rice Al tolerance, was mapped at ~40 Mbp from qALT5. We demonstrate for the first time that ZmNrat1 is preferentially expressed in maize root tips and is up-regulated by Al, similarly to OsNrat1 in rice, suggesting a role of this gene in maize Al tolerance. The strongest-effect QTL was mapped on chromosome 6 (qALT6), within a 0.5 Mbp region where three copies of the Al tolerance gene, ZmMATE1, were found in tandem configuration. qALT6 was shown to increase Al tolerance in maize; the qALT6-NILs carrying three copies of ZmMATE1 exhibited a two-fold increase in Al tolerance, and higher expression of ZmMATE1 compared to the Al sensitive recurrent parent. Interestingly, a new source of Al tolerance via ZmMATE1 was identified in a Brazilian elite line that showed high expression of ZmMATE1 but carries a single copy of ZmMATE1.

CONCLUSIONS

High ZmMATE1 expression, controlled either by three copies of the target gene or by an unknown molecular mechanism, is responsible for Al tolerance mediated by qALT6. As Al tolerant alleles at qALT6 are rare in maize, marker-assisted introgression of this QTL is an important strategy to improve maize adaptation to acid soils worldwide.

Colorectal cancer in nonagenarians

AIM

The aim of the study was to analyze the short-term and long-term outcomes of nonagenarians treated for colorectal cancer.

METHOD

A retrospective analysis was performed of 74 patients, ≥ 90 years of age, diagnosed with colorectal cancer during the period 1986-2009. Comorbidity, American Society of Anesthesiology (ASA) grade, symptoms, diagnosis, treatment, mortality, morbidity and survival were analyzed.

RESULTS

Of the 74 patients, 48 (65%) were women. Twenty-two patients were classified as ASA grade I-II, 26 as ASA grade III and 26 as ASA grade IV-V. Thirty-one (42%) had intestinal obstruction at the time of diagnosis. Twenty-two (30%) patients were diagnosed during the period 1986-2000 and 52 (70%) were diagnosed between 2001 and 2009. Forty-four (59%) patients underwent surgery, of whom 19 (49%) were treated as an emergency. Eleven (25%) patients died postoperatively, with mortality rates of 12% (3/25) for elective surgery and 42% (8/19) for emergency surgery. Surgical mortality for ASA grade I and grade II patients was 5% (1/20) and their 5-year survival rate (postoperative mortality excluded) was 44%, whereas 5-year survival for ASA grade III patients who underwent surgery was 12.5% and surgical mortality was 25% (4/16). There were no survivors beyond 36 months among patients who did not receive surgery.

CONCLUSION

Our results indicate that elective and emergency colorectal surgery can be performed with acceptable rates of mortality and morbidity on nonagenarian patients in good general condition with low perioperative risk. The 5-year survival rate was related to ASA grade and to the use of surgery.

Correction of distal limb prolapse of a diverting colostomy by stapling under sedation

AIM

To describe a surgical technique to treat colostomy prolapse as a day case procedure with the patient under sedation and analgesia.

METHOD

A 60-mm GIA Universal Stapler is inserted into the lumen of the prolapsed colon at right angles to the contour of the abdominal wall. Several firings are then made to completely divide the prolapsed colon. The instrument is then placed parallel to the skin to remove the prolapsed portion leaving 1-2 cm of bowel above the level of the skin.

RESULTS

Two patients underwent the procedure. The operation times were 30 and 13 min. Both took oral liquids 2 h after surgery and solids 2 h later. They were discharged at 24 and 4 h after surgery, respectively. No postoperative pain was reported in either case. At 14 and 6 months of follow-up there has been no recurrence.

CONCLUSION

Stapling treatment of prolapsed colostomies has the advantage of being an extra-abdominal procedure. It is performed under sedation and analgesia, the operation time is very short, recovery to normal life is rapid and there is less likelihood of complications by avoiding a laparotomy.

[High blood pressure prevalence in Oporto sedentary and regular exercise practicing people]

INTRODUCTION

The association between the lack of exercise and prevalence of high blood pressure (HBP) is a well known fact. The non-pharmacological treatment for HBP includes regular aerobic exercise practicing.

METHODS

A total of 900 individuals, aged above 40, resident in Oporto, representing the 15 parishes of the city, were approached to answer a questionnaire about exercise habits and diagnosis of HBP. The exercise practitioner was defined as the one who practices aerobic exercise for a minimal period of 30 minutes at least 3 times a week. For data analysis non-parametric tests (Pearson's Chi-Square) were used through the Statistical Package for the Social Sciences (SPSS) software.

RESULTS

The HBP prevalence in the sample was 39.67% (Confidence Interval (IC) 95%, 36,46% to 42,87%). The HBP prevalence in the exercise practitioners was inferior to the one of the non-practitioners (13,78% vs 25,89%, p < 0,001). This result is valid to the male 33,5% vs 51,6%, p < 0,001) and female population (27,1% vs 51,9%, p < 0,001), as well as to the population without the most frequent HBP-related comorbidities (21,8% vs 44,6%, p < 0,001).

CONCLUSIONS

The HBP prevalence in the population resident in Oporto city is higher in the non-practitioners of regular exercise. The HBP prevalence, in both sexes, is higher in the non-practitioners of exercise. Finally, we can also conclude that the studied comorbidities don't bias the obtained results because the group of individuals who don't have them the HBP prevalence is still higher in the group of sedentary.

Anastomotic leak after manual circular stapled left-sided bowel surgery: analysis of technology-, disease-, and patient-related factors

BACKGROUND

Anastomotic leak rates after colorectal surgery remain high. In most left-sided colon and rectal resection surgeries, a circular stapler is utilized to create the primary bowel anastomosis. However, it remains unclear whether a relationship between circular stapler technology and anastomotic leak in left-sided colorectal surgery exists.

METHODS

A post-hoc analysis was conducted using a prospectively collected data set of patients from the 2017 European Society of Coloproctology snapshot audit who underwent elective left-sided resection (left hemicolectomy, sigmoid colectomy, or rectal resection) with a manual circular stapled anastomosis. Rates of anastomotic leak and unplanned intensive care unit stay in association with manual circular stapling were assessed. Patient-, disease-, geographical-, and surgeon-related factors as well as stapler brand were explored using multivariable regression models to identify predictors of adverse outcomes.

RESULTS

Across 3305 procedures, 8.0% of patients had an anastomotic leak and 2.1% had an unplanned intensive care unit stay. Independent predictors of anastomotic leak were male sex, minimal-access surgery converted to open surgery, and anastomosis height C11 (lower third rectum) (all P < 0.050). Independent predictors of unplanned intensive care unit stay were minimal-access surgery converted to open surgery and American Society of Anesthesiologists grade IV (all P < 0.050). Stapler device brand was not a predictor of anastomotic leak or unplanned intensive care unit stay in multivariable regression analysis. There were no differences in rates of anastomotic leak and unplanned intensive care unit stay according to stapler head diameter, geographical region, or surgeon experience.

CONCLUSION

In patients undergoing left-sided bowel anastomosis, choice of manual circular stapler, in terms of manufacturer or head diameter, is not associated with rates of anastomotic leak and unplanned intensive care unit stay.