OPEN ACCESS Research Article

Novel insights into the genomic basis of citrus canker based on the genome sequences of two strains of Xanthomonas fuscans subsp. aurantifolii Abstract Background: Citrus canker is a disease that has severe economic impact on the citrus industry worldwide. There are three types of canker, called A, B, and C. The three types have different phenotypes and affect different citrus species. The causative agent for type A is Xanthomonas citri subsp. citri, whose genome sequence was made available in 2002. Xanthomonas fuscans subsp. aurantifolii strain B causes canker B and Xanthomonas fuscans subsp. aurantifolii strain C causes canker C. Results: We have sequenced the genomes of strains B and C to draft status. We have compared their genomic content to X. citri subsp. citri and to other Xanthomonas genomes, with special emphasis on type III secreted effector repertoires. In addition to pthA, already known to be present in all three citrus canker strains, two additional effector genes, xopE3 and xopAI, are also present in all three strains and are both located on the same putative genomic island. These two effector genes, along with one other effector-like gene in the same region, are thus good candidates for being pathogenicity factors on citrus. Numerous gene content differences also exist between the three cankers strains, which can be correlated with their different virulence and host range. Particular attention was placed on the analysis of genes involved in biofilm formation and quorum sensing, type IV secretion, flagellum synthesis and motility, lipopolysacharide synthesis, and on the gene xacPNP, which codes for a natriuretic protein. Conclusion: We have uncovered numerous commonalities and differences in gene content between the genomes of the pathogenic agents causing citrus canker A, B, and C and other Xanthomonas genomes. Molecular genetics can now be employed to determine the role of these genes in plant-microbe interactions. The gained knowledge will be instrumental for improving citrus canker control. Background Citrus canker is a disease with worldwide distribution that has severe economic impact on the citrus industry [1,2]. Disease symptoms consist of water soaked lesions that develop into blisters, then pustules, and, finally, can-kers. In severe cases, citrus canker can lead to defoliation


Introduction
Duplex kidney system is a relatively common anomaly in the renal system [1], [2], [3].It is frequently asymptomatic but when being symptomatic the most presenting problems are flank pain and urinary tract infection with an atrophic upper pole which may also cause hypertension [3].The standard treatment for a duplex kidney with a poorly functioning upper pole moiety is an upper pole heminephrectomy [3].This procedure is usually performed by open surgery but with recent developments in endourology techniques and uro-laparoscopy, many attempts started to do this procedure laparoscopically [4], [5], [6].There are few reports in laparoscopic heminephrectomy in children that are mainly done with retroperitoneal approach [4], [5], [6], and there is just one large series in adults with acceptable results [7].In this article we describe our results and patients outcomes with laparoscopic Transperitoneal heminephrectomy in our consecutive cases.

Materials and methods
From February 2001 to May 2007, 14 patients (10 females, 4 males) with complete duplex kidneys were presented with flank pain or UTI leading to final diagnosis of non functioning upper moiety which became candidate for Transperitoneal laparoscopic heminephrectomy.Patients did not have any previous history of ipsilateral renal surgery.Prior to the procedure, complete radiologic evaluation including abdominopelvic sonography, intravenous urography (IVU) and abdomino-pelvic CT scan were contemplated in all patients to delineate renal anatomy and hydronephrosis.By DMSA isotope scan, hypofunctioning of this moiety was confirmed.In patients suspected of vesico-ureteral reflux, voiding cystourethrography (VCUG) was also performed.All patients were admitted the day before operation; received adequate bowel preparation and other needed medications.Renal function tests as well as complete blood count, urine analysis and culture were all performed during that period.

Surgical technique
With the patients under general anesthesia, a foley catheter as well as a nasogastric tube was inserted and they were placed in a 60 degrees lateral decubitus position with minimal flexion of the operating table supported by adequate padding.The abdominal cavity was explored using 4 port transperitoneal approach for left side operation (a camera port at the level of umbilicus lateral to the rectus muscle, two 5 mm and one 10 mm trocars as working ports).For right side operation, the same trocar arrangement was employed but another 5 mm subxiphoid port was added for liver retraction.After incising the white line of Toldt, superior retraction of spleen/liver and medial mobilization of colon (and duodenum: on right side), exposure to the renal pedicle was made possible.After complete dissection of both renal artery and vein, Gerota's fascia was incised and the kidney fully mobilized within the Gerota's fascia [7].Afterwards, the dilated ureter of the corresponding nonfunctioning moiety was localized and carefully dissected to the renal hilum.Care was taken not to induce ureteral devascularization of the other healthy ureter.The diseased ureter was clipped and divided at the level of lower pole and used as a handle and guide to facilitate the dissection of segmental branches of renal artery and vein which supplied the nonfunctioning moiety.Such dissection was embarked as meticulous as possible trying not to induce any ischemia and/or injury to the healthy moiety.Then, the corresponding segmental renal artery and vein were doubly clipped and divided; the nonfunctioning renal moiety was incised and separated from the whole renal unit on the demarcated ischemic line, using a ureteric stamp as a handle which facilitated this part of the procedure.No collecting system reconstruction was made.The specimen was extracted from the abdominal cavity through a 10 mm port.The retroperitoneum irrigated and suctioned, hemostasis of the renal cut surface was ensured and an external drainage was placed with a tubular drain.
All patients received prophylactic peri-operative intravenous antibiotics as of our routine program [8].Upon ambulation, Foley catheter was removed.Complete blood count and renal function tests were rechecked and assigned 6 hours after the operation as post-procedural analysis.If they were normal, daily evaluation was embarked.Surgical demographics such as operative time, blood loss, early and late complications were registered.Three-month follow-up IVP was performed in all patients to assess about the functional status of the remained ipsilateral renal moiety.

Results
Fourteen patients (10 female, 4 males) underwent laparoscopic transperitoneal heminephrectomy.Ten cases (71.5%) were adults and 4 cases (28.5%) were children (ages 3, 3, 5, and 5 years).Overall mean age of the patients was 24.2±16.8years old (adult age range: 18 to 52 years; pediatric age range (Table 1): 3 to 5 years).The main presenting symptoms were flank pain in 10 patients (71.4%) followed by urinary tract infection in three (21.4%).In one pediatric patient follow up of prenatal hydronephrosis confirmed the diagnosis of nonfunctioning upper pole moiety.Blood pressure was normal in all patients.In eight patients (57.14%) the atrophic part was located in the left side and in six patients (42.86%) in the right side.We had no case of bilateral anomalies.The mean operative time was 203 min., SD ±80 (range 95 to 360 min).Estimated blood loss was negligible.No major intra-operative or early complication was identified.Differences in pre-operative and post-operative hemoglobin and creatinine were not significant.Mean hospital stay was 4.1 days (range 2 to 7).In one patient mild bleeding occurred due to injured abdominal wall vessels in the trocar site.On the second postoperative day the patient's hemoglobin level dropped from 11.1 g/dl to 9.2 g/dl and blood transfusion was performed.The patient's abdominal wall hematoma, observed by daily ultrasonography, resolved spontaneously within one week.On patients' mean follow up of 32 months there was not any pain or episodes of recurrent urinary tract infection in any case.In all patients post-operative IVPs were done after 3 months.Follow-up IVPs showed ipsilateral functioning moieties with an intact collecting system in all cases (Figure 1, Figure 2) except our first patient in whom atrophic kidney was detected.In this patient and during the renal pedicle dissection the lower pole artery was injured because of vascular anomalies.No hypertension was detected in this case after long-term follow-up in spite of atrophic kidney.

Discussion
Duplication of the ureter and renal pelvis is the most common anomaly of the upper urinary tract with an incidence of 1 in 125 or 0.8% [1], [2], [3].The anomaly can often goes unrecognized until adulthood [9].The upper moiety is frequently obstructed, poor functioning, and can become symptomatic due to urinary tract infection or flank pain.The standard surgical treatment of a nonfunctioning symptomatic renal moiety is ipsilateral heminephrectomy.Recent advances in laparoscopic techniques have led to the selection of laparoscopic surgery for many if not most urological procedures.It can be done retroperitoneal or transperitoneally.The first case of a laparoscopic partial nephrectomy was reported by Winfield et al. in 1992 [10].With further development of the technique, Jordan and Winslow performed the first laparoscopic upper pole heminephrectomy in 1993 [11].Since then several reports on laparoscopic heminephrectomy have been published describing advantages, disadvantages and complications of the procedure.Based on the literature review, and regardless of applied techniques, the main complications of laparoscopic heminephrectomy are urinoma, urine leakage, recurrent urinary tract infections, postoperative hypertension, and functional loss of the remaining moiety [9], [12].In our series just one case of functional loss of the remaining moiety was seen due to inadvertent injury of lower pole renal artery.This complication was detected as ipsilateral renal atrophy at follow-up IVP, 3 months after operation.Almost all of the published series reported the efficacy of the procedure in pediatric patients.Series which have exclusively studied the efficacy of the procedure in adult cases have recently been published by Abouassaly et al. [9] and Gao et al. [12].Abouassaly et al. described their experience with the procedure within a series of adult patients.None of their cases required conversion to open surgery.Development of an urinoma in one case was the only reported complication [9].Another adult series was reported by Gao et al. [12].In his series of 18 cases of transperitoneal laparoscopic heminephrectomy no major complication or open conversion occurred.The mean operative time was 142 min and the mean estimated blood loss was 196 mL.The mean hospital stay was 6 days.Only one case of postoperative urine leakage was reported in his series that was treated with prolonged urethral catheterization.Castellan et al. published their experience in a series of 48 pediatric patients (mean age 4.08 years) who underwent transperitoneal and retroperitoneal laparoscopic heminephrectomy [13].Mean operative time was 125 and 133 minutes for transperitoneal and retroperitoneal, respectively.Mean hospitals stay was 2.6 days in the transperitoneal and 2.3 days in the retroperitoneal group.One retroperitoneal procedure required conversion to open surgery.In this largest series of laparoscopic heminephrectomy, complications were seen in 5 patients (10%), including urinary leak, urinoma, pneumothorax, recurrent urinary tract infection, and postoperative hyper-tension.The authors found that laparoscopic heminephrectomy can be performed with minimal morbidity, improved cosmesis and short hospital stay.Laparoscopic approach to heminephrectomy offers the patient the typical benefits of laparoscopy including shorter hospital stay, minimal morbidity, improved cosmesis, and lower need for analgesic use [4], [5], [6], [9], [14], [15].Improved preservation of the functioning pole of kidney could be an advantage of laparoscopy specifically mentioned in this procedure.It is of worth noting that the objective of heminephrectomy is the safe maximal removal of the nonfunctioning moiety and simultaneous maximal preservation of the functioning pole.Laparoscopic approach enables an excellent differentiation of each hemirenal tissue, separating the ill kidney and preserving the maximal possible function for the other half-kidney [15].Our series consists of a combination of children and adult patients.There was not any major or minor operative complication in our series except one in which blood transfusion was needed because of trocar site hemorrhage due to injured abdominal wall vessels.Operative time was reduced due to increased surgical team experience.Mean hospital stay was only 4 days which is much less than open series.In mean follow up period of 32 months, the remaining kidney functioned properly (Figure 1, Figure 2).Flank pain was also resolved in all patients during follow up.

Conclusion
Laparoscopic procedures have become standard of care in some urologic disorders.Laparoscopic heminephrectomy has a valuable role in the treatment of duplex kidneys.It can be performed with minimal morbidity and acceptable results.Excellent visualization during laparoscopy helps better preservation of renal pedicle especially in pediatric age groups and offers a preferred approach for management of atrophic renal moieties in duplex systems.

Notes Competing interests
The authors declare that they have no competing interests.

Figure 1 : 7 Figure 2 :
Figure 1: Preoperative IVU shows dilated upper pole in right side in patient no.7