Histological study of the thin membranous dense connective tissues around the curving portion of the bilateral recurrent laryngeal nerves

OBJECTIVE/AIM

We aimed to demonstrate the anatomical relationship between the recurrent laryngeal nerves (RLNs), thin membranous dense connective tissue (TMDCT [e.g., the visceral or vascular sheaths around the esophagus]), and the lymph nodes around the esophagus at the curving portion of the RLNs for rational and efficient lymph node dissection.

METHODS

Transverse sections of the mediastinum at 5 mm or 1 mm intervals were obtained from four cadavers. Hematoxylin and eosin staining and Elastica van Gieson staining were performed.

RESULTS

The visceral sheaths could not be clearly observed the curving portions of the bilateral RLNs, which were observed on the cranial and medial side of the great vessels (aortic arch and right subclavian artery [SCA]). The vascular sheaths could be clearly observed. The bilateral RLNs diverged from the bilateral vagus nerves, which ran along with the vascular sheaths, went up around the caudal side of the great vessels and the vascular sheath, and ran cranially on the medial side of the visceral sheath. Visceral sheaths were not observed around the region containing the left tracheobronchial lymph nodes (No. 106tbL) or the right recurrent nerve lymph nodes (No. 106recR). The regions containing the left recurrent nerve lymph nodes (No. 106recL) and the right cervical paraesophageal lymph nodes (No. 101R) were observed on the medial side of the visceral sheath, with the RLN.

CONCLUSION

The recurrent nerve, which branched off from the vagus nerve descending along the vascular sheath, ascended the medial side of the visceral sheath after inversion. However, no clear visceral sheath could be identified in the inverted area. Therefore, during radical esophagectomy, the visceral sheath along No. 101R or 106recL may be recognized and available.

[A Case of HER2 Positive Unresectable Gastric Cancer Leading to Conversion Therapy with Chemotherapy]

A 72‒year‒old man visited our hospital with a chief complaint of epigastralgia. Upper gastrointestinal endoscopy revealed type 3 advanced gastric cancer at the body of the stomach. Following an investigation, he was diagnosed with human epidermal growth factor receptor 2‒positive gastric cancer with invasion to the pancreas as well as the paraaortic lymph node, and multiple liver metastases were also observed. The cancer was judged to be cT4a, N2M1(H1 LYM: No. 16), cStage Ⅳ and thus was considered suitable for chemotherapy. We performed capecitabine plus cisplatin plus trastuzumab therapy. After 3 courses, the primary lesion and swollen lymph nodes decreased in size. After 20 chemotherapy courses, the primary lesion relapsed, so conversion surgery was performed. The patient underwent total gastrectomy, distal pancreatectomy, and partial resection of the liver. We planned to perform adjuvant chemotherapy, but the patient declined it because of anorexia. At 18 months after the operation, recurrence of the tumor was detected at the celiac artery. Chemotherapy was performed as follows: capecitabine plus trastuzumab 10 courses, ramucirumab plus paclitaxel, irinotecan, and nivolumab. However, the patient eventually died 71 months after the first visit.

[REPARATIVE SURGERY OF PRESSURE-REGULATING BALLOON HERNIA AFTER ARTIFICIAL URINARY SPHINCTER REPLACEMENT: A CASE REPORT]

A 74-year-old male with post-prostatectomy incontinence underwent artificial urinary sphincter replacement due to device malfunction. Three months after the replacement surgery, he presented for a consultation due to a bulging area in his lower abdomen. Computed tomography revealed a hernia of the pressure-regulating balloon (PRB), while the device was working well. In the reparative surgery, reopening the lower abdominal incision, the PRB was carefully restored to its previous position after creating a sufficient submuscular space. As the rectus abdominis fascia showed an adequate strength, the fascia was tightly sutured without using a prosthetic mesh. Thereafter, the patient has been free from incontinence for two and a half years without hernia recurrence. Given the mechanical nature of the device, replacement surgery is sometimes required over time. Tissue fragility due to repetitive surgeries and increasing ambient pressure due to space reduction derived from the PRB deflation could cause PRB hernia. Such cases can be treated under careful manipulation without damaging the device. Considering the future potential need for repeated surgery, it would be preferable not to use prosthetic mesh, as it can cause dense adhesion.

The evaluation of the hemodynamics of a gastric tube in esophagectomy using a new noninvasive blood flow evaluation device utilizing near-infrared spectroscopy

OBJECTIVE

We herein evaluated the hemodynamics of a gastric tube in esophagectomy using a new noninvasive blood flow evaluation device utilizing near-infrared spectroscopy.

METHODS

Thirty-two cases of subtotal esophagectomy and gastric tube reconstruction for esophageal cancer were studied. The new device measures the regional tissue saturation of oxygen (rSO₂: 0-99%) and total hemoglobin index (T-HbI: 0-1.0) with a small sensor. We measured these values at the antrum (point A), final branch of the right gastroepiploic artery (point B) and planned anastomotic point (point C) before and after gastric tube formation. The values at the three points were compared, and the gradients at the three points from before to after gastric tube formation were compared.

RESULTS

The mean values of rSO₂ at point A, B, and C before gastric tube formation were 57.2%, 57.8% and 56.0%, and those after formation were 54.6%, 58.0% and 55.8%, respectively. There was no significant difference in the comparison of the rSO₂ gradient before and after formation (p = 0.167). The mean values of T-HbI at point A, B, and C before formation were 0.126, 0.178 and 0.211, and those after formation were 0.167, 0.247 and 0.292, respectively. There was no significant difference in the gradient of the increase before and after formation (p = 0.461).

CONCLUSION

A new device has shown that the gastric tube used in our facility is one that maintains tissue saturation of oxygen and does not cause excessive congestion at anastomosis.

Flexible Gastric Tube: A Novel Gastric Tube Formation Method to Prevent Anastomotic Leakage

Gastric tube reconstruction is now the method most frequently used for digestive tract reconstruction after the resection of esophageal carcinoma. In our institute, a ^"flexible^" gastric tube designed to supply a sufficient amount of blood to the tip of the gastric tube (the same as a subtotal gastric tube) and simultaneously provide sufficient length for tension-free anastomosis in the cervical surgical field (the same as a narrow gastric tube) was introduced. This gastric tube formation method has contributed to reducing the rate of anastomotic leakage.

Aortic inflation with agar injection is a useful method of cadaveric preparation which creates a mediastinal anatomy that better mimics the living body for surgical training

In cadavers, even Thiel-embalmed cadavers, the arteries (especially the thoracic aorta) are extremely collapsed. This is in marked contrast to the state of the arteries in a living body. Aortic inflation is necessary to improve this unfavorable situation for anatomical observation or dissection. To inflate the aorta, we injected 500 ml of hot liquid agar into the aorta using a 18-Fr catheter inserted into the common femoral artery and subclavian artery. The injected agar then rapidly cools to room temperature and solidifies. As a result, the thoracic aorta remains sufficiently and constantly inflated in the mediastinum. This method is not only easy and inexpensive, but also useful and effective for achieving a life-like anatomy in cadavers used in surgical training for operations involving mediastinal organs, with the exception of the heart and great vessels.

CHAC1 overexpression in human gastric parietal cells with Helicobacter pylori infection in the secretory canaliculi

BACKGROUND

Cation transport regulator 1 (CHAC1), a newly discovered enzyme that degrades glutathione, is induced in Helicobacter pylori (H. pylori)-infected gastric epithelial cells in culture. The CHAC1-induced decrease in glutathione leads to an accumulation of reactive oxygen species and somatic mutations in TP53. We evaluated the possible correlation between H. pylori infection and CHAC1 expression in human gastric mucosa.

MATERIALS AND METHODS

Both fresh-frozen and formalin-fixed paraffin-embedded tissue samples of gastric mucosa with or without H. pylori infection were obtained from 41 esophageal cancer patients that underwent esophago-gastrectomy. Fresh samples were used for real-time polymerase chain reaction for H. pylori DNA and CHAC1 mRNA, and formalin-fixed samples were used for immunohistochemistry with anti-CHAC1 and anti-H. pylori monoclonal antibodies. Double-enzyme or fluorescence immunohistochemistry and immuno-electron microscopy were used for further analysis.

RESULTS

Significant CHAC1 overexpression was detected in H. pylori-infected parietal cells that expressed the human proton pump/H,K-ATPase α subunit, whereas a constitutively low level of CHAC1 mRNA expression was observed in the other samples regardless of the H. pylori infection status, reflecting the weak CHAC1 expression detected by immunohistochemistry in the fundic-gland areas. Immuno-electron microscopy revealed intact H. pylori cells in the secretory canaliculi of infected parietal cells. Some parietal cells exhibited positive nuclear signals for Ki67 in the neck zone of the gastric fundic-gland mucosa with H. pylori infection.

CONCLUSION

Cation transport regulator 1 overexpression in H. pylori-infected parietal cells may cause the H. pylori-induced somatic mutations that contribute to the development of gastric cancer.

Mid- and long-term outcomes of endoscopic resection for submucosal esophageal cancer types pT1b-SM1 and pT1b-SM2

Background and study aims  Endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR) are promising therapeutic options for early esophageal cancer (EC). The factors that can affect mid- and long-term survival in patients with submucosal EC (SM1 and SM2) have not been described in the literature. We aim to describe clinicopathological outcomes and factors that can affect the mid- and long-term survival in patients with resected submucosal tumors. Patients and methods  We performed a retrospective analysis of patients who underwent endoscopic resection (ER) for submucosal tumors over a 20-year period. The final study population included 119 cases with 137 lesions. Information was collected according to the Japanese Classification of Esophageal Cancer 11-edition and factors affecting survival for 2 and 5 years after ER were analyzed. Results  EMR was performed in 99 cases (72.3 %), ESD in 38 cases (27.7 %). There were no significant complications. Two- and 5-year survival rates were 91 % and 82 %, respectively. Mean age was 67.22 years (± 9.49 years), mortality caused by EC occurred in 13 cases (11 %). Factors that had a significant impact on long-term survival were age > 65 years ( P  = 0.0026), number of resected specimens ( P  = 0.0031), presence of another progressive disease (not EC) ( P  ≤ 0.001), recurrence ( P  = 0.0002), and relation between histopathological positive vertical margin and recurrence ( P  = 0.0112). Conclusions  ER is viable treatment for esophageal submucosal cancer, selection between ESD/EMR can depend on tumor size and patient condition, and en bloc ER is the recommended technique for submucosal tumors. Long-term survival factors were identified.

Histological study of the thin membranous structure made of dense connective tissue around the esophagus in the upper mediastinum

BACKGROUND

The structure of the fascia in upper mediastinum has already been reported from gross anatomical viewpoints by Sarrazin. But it is necessary to understand meticulous anatomy for thoracoscopic or mediastinoscopic surgery. So herein, we investigate histologically the thin membranous structure made of dense connective tissues.

METHODS

Semi-sequential transverse sections of the mediastinum were obtained from three cadavers. Hematoxylin and eosin staining, Elastica van Gieson staining, and Masson trichrome staining were performed to identify the presence and location of the thin membranous structure made of dense connective tissues.

RESULTS

The "visceral sheath" and "vascular sheath," as previously described by Sarrazin, were observed histologically. These two thin membranous structures do not surround the esophagus and trachea cylindrically. In addition, the "visceral sheath" on the right side of the upper mediastinum was unclear in comparison to the left side. The "visceral sheath" (on the left side) gradually became unclear, and seemed to almost disappear; the esophagus was found to be very close to the thoracic duct on the caudal side of the bifurcation of the trachea. Although the left recurrent nerve was located inside the "visceral sheath" in all cadavers, the left recurrent nerve lymph nodes were located inside the "visceral sheath" in cadaver 1 and between the "visceral sheath" and "vascular sheath" in cadaver 3.

CONCLUSION

The "visceral sheath" around the esophagus in the upper mediastinum was histologically demonstrated; however, the findings were not constant.

Detection of Second Primary Malignancies of the Esophagus and Hypophraynx in Oral Squamous Cell Carcinoma Patients

Objective

To assess the usefulness of modified esophagogastroduodenoscopy (EGD) for the detection of second primary malignancies of the esophagus or hypopharynx in patients with oral squamous cell carcinoma and determine the association between the oral lesion subsite and esophageal or hypopharyngeal lesion occurrence.

Study Design

Retrospective review.

Methods

In total, 166 patients with oral squamous cell carcinoma without any established symptoms of esophageal or hypopharyngeal squamous cell carcinoma underwent modified EGD based on the Valsalva maneuver and U-turn method, image-enhanced endoscopy, and chromoendoscopy using Lugol's iodine for diagnosis. All suspected lesions were biopsied to determine the clinical stages and duplication rates. Odds ratios for the occurrence of duplicate lesions according to the oral lesion subsite were determined.

Results

In total, 37 esophageal and 16 hypopharyngeal lesions were detected. According to the Union for International Cancer Control/American Joint Committee on Cancer classification (2009), 75.7% and 5.4% esophageal lesions were classified as stage IA and IB, respectively, and 50% and 18.8% hypopharyngeal lesions as stage II and stage I, respectively. Approximately 59.1% and 50% esophageal and hypopharyngeal lesions, respectively, were successfully treated by endoscopic resection. Oral lesions involving the floor of the mouth were more frequently accompanied by second primary malignancies of the esophagus or hypopharynx.

Conclusions

Modified EGD is an effective noninvasive technique for early diagnosis and treatment of second primary malignancies of the esophagus and hypopharynx in patients with oral squamous cell carcinoma. In particular, patients with floor of the mouth lesions need close monitoring for hypopharyngeal and esophageal lesions.

Level of Evidence

3b.

Comparative Study of Predictive Mortality Scores in Esophagectomy with Three-Field Lymph Node Dissection in Patients with Esophageal Cancer

BACKGROUND/AIM

Esophagectomy is still the best therapeutic option for curing resectable esophageal cancer (EC). Radical surgical resection with three-field lymphadenectomy (3FLD) is a potentially curative treatment option. We compared the predictive accuracy of 5 different scores in patients with EC who underwent 3FLD.

METHODS

Five years' worth of medical records in a single institution were analyzed (January 2010 to January 2015) from 311 patients who underwent esophagectomy for EC. We selected 191 in whom 3FLD was performed. Mortality was calculated based on 5 predictive scores. Outcomes measures were intraoperative mortality, 30-day mortality, and 1- and 2-year mortality after surgery.

RESULTS

Intraoperative mortality and 30-day mortality after surgery was 0%; 1 and 2-year mortality were 19.8 and 31.4%, respectively. The area under the curve showed poor discriminatory power for all 5 scores (<0.7). In one-way analysis of variance, for 1 year mortality, Portsmouth-Physiological and Operative Severity Score for mortality (P-Possum) was significant (p = 0.0424); in a multivariable analysis for 2-year mortality, P-Possum (p < 0.0001) remained significant.

CONCLUSION

There is no accurate prognosis score for esophagectomy in patients who undergo high-risk procedures like 3FLD. New scores are needed to predict the mortality after 3FLD with good discriminatory power. Independent factors affect survival and may function as the baseline for obtaining a new accurate mortality score.

Comparative analysis of avascular areas in superficial esophageal squamous cell carcinomas using in vivo and ex vivo magnifying endoscopy

BACKGROUND AND STUDY AIMS

 An avascular area (AVA), one of the microvasculature changes in superficial esophageal cancers, appears when a tumor demonstrates a bulky growth pattern. We aimed to compare endoscopic and histopathological findings by observing formalin-fixed AVA specimens using magnifying endoscopy.

PATIENTS AND METHODS

 A prospective analysis was conducted on 16 patients with superficial esophageal cancer, including AVA, who underwent endoscopic submucosal dissection (ESD). Magnifying endoscopy and blue laser imaging were used to identify AVAs. After the ESD, the AVA width was measured on formalin-fixed specimens using magnifying endoscopy, and AVA thickness and depth were determined after hematoxylin and eosin staining using microscopy.

RESULTS

 Mean AVA widths of M1, M2, and M3/SM-lesions were 0.434, 0.578, and 0.835 mm, respectively (M1 vs. M2, P = 0.16; M2 vs. M3/SM-, P  = 0.07). Mean AVA thicknesses of M1, M2, and M3/SM-lesions were significantly different (0.176, 0.518, and 0.800 mm; M1 vs. M2, P < 0.01; M2 vs. M3/SM-, P  < 0.05). There was a significant correlation between AVA width and thickness.

CONCLUSIONS

 AVA size can be measured accurately on formalin-fixed specimens with magnifying endoscopy. AVA thickness can be useful for determining tumor depth.

A prospective study of nutritional supplementation for preventing oral mucositis in cancer patients receiving chemotherapy

BACKGROUND AND OBJECTIVES

Patients undergoing chemotherapy often develop distressing adverse effects such as oral mucositis and diarrhea. Nutritional support with elemental diet is effective against various gastrointestinal complications and may exert protective effects against adverse effects induced by chemotherapy. To evaluate the influence of elemental diet on chemotherapy-induced oral mucositis and diarrhea, we conducted a randomized control trial in patients with esophageal cancer undergoing chemotherapy.

METHODS AND STUDY DESIGN

Twenty esophageal cancer patients receiving chemotherapy with 5-fluorouracil plus cisplatin were assigned randomly to one of the following two groups: (1) receiving elemental diet with Elental (one pack per day) for 14 days and (2) not receiving Elental during chemotherapy. The severity of oral mucositis and diarrhea was graded using clinical examination by doctors and a standard questionnaireon days 1-14.

RESULTS

Based on the analysis of the standard questionnaire, the distribution of the maximum severity of oral mucositis showed a statistically significant reduction in the Elental group (p=0.020), while clinical examination showed insignificant reduction but shift toward lower grade. In the Elental group, the incidence of oral mucositis (grade >=2) reduced consistently and the median grade was lower at all-time points. Regarding diarrhea, no difference was observed between the two groups based on the analysis of the standard questionnaire and clinical examination results.

CONCLUSIONS

This study illustrates the effectiveness of oral elemental diet in preventing oral mucositis during chemotherapy. This is a preliminary report and further study with larger patients groups should be devoted to optimization of efficacy.

A Pilot Trial of S-1 and Paclitaxel in Unresectable or Postoperative Recurrent Esophageal Squamous Cell Carcinoma Pretreated by Fluorouracil, Cisplatin, and Docetaxel Chemotherapy

BACKGROUND/AIMS

This study documents the clinical efficacy and toxicity of S-1 and paclitaxel (S1/PTX) in patients with unresectable or postoperative recurrent esophageal squamous cell carcinoma (ESCC) who had been previously treated with fluorouracil (5FU), cisplatin, and docetaxel.

METHODS

Twenty-eight ESCC patients treated using S1/PTX at our institute since 2010 were enrolled in this study. S1 was administered orally at a dose of 80 mg/m2/day from days 1 to 14, and PTX was administered intravenously on days 1 and 8 at a dose of 80-100 mg/m2.

RESULTS

A total of 106 cycles (median 2.5 cycles, range 1-12 cycles) were administered. The response rate was 14.8%, including 3 complete responses. The median progression-free survival time was 137 days, and the median overall survival time was 306 days. Severe neutropenia occurred in 13 patients, and 3 showed febrile neutropenia. All non-hematological toxicities were mild, and peripheral nerve paralysis was observed in 2 patients.

CONCLUSION

S1/PTX was found to have tolerable clinical efficacy in terms of the response rate, survival and toxicity in patients with unresectable or postoperative recurrent ESCC who had previously been treated with 5FU, cisplatin, and docetaxel.

Efficacy of docetaxel, cisplatin, and 5-fluorouracil chemotherapy for superficial esophageal squamous cell carcinoma

The anticancer efficacy of docetaxel, cisplatin, and 5-fluorouracil (DCF) chemotherapy has been reported to be better than that of conventional regimens for advanced or relapsed esophageal squamous cell carcinoma (ESCC), and may become a standard therapy for this disease. Because it is extremely rare for chemotherapy to be administered as treatment for early cancer alone, the efficacy of DCF for superficial ESCC remains unknown. However, from a clinical oncological standpoint, it is important to investigate the anticancer efficacy of chemotherapy for early cancer, which may be useful for understanding the development of treatment resistance against chemotherapy in cancer. This retrospective, single-center analysis included 28 patients with superficial ESCC who received DCF for synchronous head and neck squamous cell carcinoma between June 2007 and July 2013. The response rate to DCF was 60.7%. In 14 of 17 patients who had been judged to have a complete response, local recurrence was eventually confirmed by follow-up esophagogastroduodenoscopy. The median progression-free survival for all 28 patients was 6.0 months. The anticancer efficacy of DCF was not found to be dependent on tumor progression stage or on the volume of local and metastatic tumors but on the drug sensitivity of the individual. Our results suggest that the efficacy of DCF against superficial esophageal squamous cell carcinoma appears to be limited to local lesions and metastases of regional lymph nodes, and the expected effect of DCF for early ESCC is similar to that for advanced, metastatic, or recurrent esophageal cancer.

Case of Superficial Cancer Located at the Pharyngoesophageal Junction Which Was Dissected by Endoscopic Laryngopharyngeal Surgery Combined with Endoscopic Submucosal Dissection

Aims. In order to determine the indications of transoral surgery for a tumor located at the pharyngoesophageal junction, the trumpet maneuver with transnasal endoscopy was used. Its efficacy is reported here. Material and Methods. An 88-year-old woman complaining of dysphagia, diagnosed with cervical esophageal cancer, and hoping to preserve her voice and swallowing function was admitted to our hospital. Conventional endoscopy showed that the tumor had invaded the hypopharynx. When inspecting the hypopharynx and the orifice of the esophagus, we asked the patient to blow hard and puff her cheeks with her mouth closed (trumpet maneuver). After the trumpet maneuver, the pharyngeal mucosa was stretched out. The pedicle of the tumor arose from the left-anterior wall of the pharyngoesophageal junction, so we decided to perform endoscopic resection. Result. Under general anesthesia, the curved laryngoscope made it possible to view the whole hypopharynx, including the apex of the piriform sinus and the orifice of the esophagus. The cervical esophageal cancer was pulled up to the hypopharynx. Under collaboration between a head and neck surgeon and an endoscopist, the tumor was resected en bloc by endoscopic laryngopharyngeal surgery combined with endoscopic submucosal dissection. Conclusion. Transnasal endoscopy using the trumpet maneuver is useful for a precise diagnosis of the pharyngoesophageal junction. Close collaboration between head and neck surgeons and endoscopists can provide good results in treating tumors of the pharyngoesophageal junction.

Is a Central Venous Catheter Necessary for the Perioperative Management of Esophagectomy? A Prospective Randomized Pilot Study Comparing Two Different Perioperative Regimens

BACKGROUND/AIMS

Our prospective randomized study examined the possibility of perioperative management of esophagectomy without a central venous catheter (CVC).

METHODS

Forty patients who underwent esophagectomy for esophageal cancer were divided into the total parenteral nutrition (TPN; receiving conventional perioperative management via a CVC) and peripheral parenteral nutrition (PPN; receiving perioperative management without a CVC) groups. Albumin and retinol-binding protein (RBP) levels were used as measurements of the nutritional status. Early postoperative complications and catheter-related complications were also evaluated.

RESULTS

The actual calories administered per kg of body weight and the albumin and RBP levels did not significantly differ between the groups. Additionally, there was no significant difference in the morbidity of early postoperative complications between the groups. Catheter-related complications were observed in 4 patients in the TPN group (2 catheter infections, 1 case of thrombosis, and 1 case of iatrogenic pneumothorax), and 4 cases of peripheral phlebitis occurred in the PPN group. The incidence of catheter-related complications did not significantly differ between the groups.

CONCLUSIONS

Perioperative management without a CVC can be safely performed in esophagectomy patients, and the decision to insert a CVC should be made based on the patient's perioperative condition.

Prognostic Factors for Post-Recurrence Survival in Patients with Thoracic Esophageal Squamous Cell Carcinoma after Curative Resection

BACKGROUND/AIMS

We investigated factors affecting the post-recurrence prognosis in order to develop adequate therapeutic guidelines for determining the indication for treatment of recurrent esophageal squamous cell carcinoma (ESCC).

METHODS

Ninety-three thoracic ESCC patients who developed postoperative recurrence after undergoing curative esophagectomy with 3-field lymphadenectomy at our institute and who received treatment for recurrence were enrolled in this study.

RESULTS

A univariate analysis showed that distant organ recurrence, the number of recurrent tumors, the longest diameter of the largest recurrent tumor, the sum of all of the longest diameters of the recurrent tumors, invasion into adjacent structures and the speed of growth of the representative recurrent tumors were significantly associated with the post-recurrence prognosis. A multivariate analysis showed that distant organ recurrence, the longest diameter of the largest recurrent tumor, invasion into adjacent structures and the speed of growth of the representative recurrent tumors were significantly associated with the prognosis. The patients whose recurrent tumor(s) did not meet all 4 of these factors showed a better prognosis. In contrast, the prognosis of the patients whose recurrent tumor(s) demonstrated all 4 factors was almost the same as that observed in the patients who did not receive any treatment for recurrence.

CONCLUSIONS

The evaluation of these 4 factors may potentially be used to determine the indication for treatment for recurrence.

Endoscopic assessment 1 day after esophagectomy for predicting cervical esophagogastric anastomosis-relating complications

BACKGROUND

There are no useful methods for predicting anastomosis-relating complications after esophagectomy; however, anastomotic leakage remains one of the most serious postoperative complications. We retrospectively investigated the appropriateness of endoscopic examinations on postoperative day 1 (POD 1) for assessing esophageal reconstruction by analyzing the endoscopic findings 1 day after the operation and evaluating the healing process at the site of anastomosis in patients treated with esophageal reconstruction.

METHODS

Between 2010 and 2013, we performed esophageal reconstructive surgery using a retrosternal gastric graft and cervical anastomosis and conducted endoscopic examinations to assess the esophagogastric anastomosis on POD 1 in 153 patients. On endoscopy performed on POD 1, we identified mucosal color change (MCC) in the proximal gastric graft as an important finding that may be indicative of local circulatory failure in gastric grafts. One week after the operation, endoscopic examinations subsequently showed significant mucosal defects around the site of anastomosis that were expected to result in anastomotic leakage as a marker of poor healing of anastomosis as well as leakage.

RESULTS

We identified the findings of MCC in 36 patients evaluated with endoscopic examinations performed on POD 1. Furthermore, the endoscopic examinations performed 1 week after the operation revealed poor healing of the anastomosis site in 23 patients, including one patient with major anastomotic leakage. Therefore, poor healing of the anastomosis site more frequently occurred in 20 of the 36 patients (55.6%) who exhibited MCC on the endoscopic examinations performed on POD 1 than in three of the 117 patients (2.6%) who had normal endoscopic findings on POD 1 (p < 0.001).

CONCLUSIONS

Early endoscopy performed on POD 1 helps to predict the development of poor healing of esophagogastric anastomosis around 1 week after the operation by identifying the findings of MCC in the proximal gastric graft.

Salvage chemoradiotherapy for locally advanced esophageal carcinomas

'Salvage chemoradiotherapy (CRT)' was introduced in 2005 to treat thoracic esophageal carcinomas deemed unresectable based on the intraoperative findings. The therapeutic concept is as follows: the surgical plan is changed to an operation that aims to achieve curability by the subsequent definitive CRT. For this purpose, the invading tumor is resected as much as possible, and systematic lymph node dissection is performed except for in the area around the bilateral recurrent nerves. The definitive CRT should be started as soon as possible and should be performed as planned. We hypothesized that this treatment would be feasible and provide good clinical effects. We herein verified this hypothesis. Twenty-seven patients who received salvage CRT were enrolled in the study, and their clinical course, therapeutic response, and prognosis were evaluated. The patients who had poor oral intake because of esophageal stenosis were able to eat solid food soon after the operation. The radiation field could be narrowed after surgery, and this might have contributed to the high rate of finishing the definitive CRT as planned. As a result, the overall response rate was 74.1%, and 48.1% of the patients had a complete response. No patient experienced fistula formation. The 1-, 3-, and 5-year overall survival rates were 66.5%, 35.2%, and 35.2%, respectively. Salvage CRT had clinical benefits, such as the fact that patients became able to have oral intake, that fistula formation could be prevented, that the adverse events associated with the definitive CRT could be reduced, and that prognosis of the patients was satisfactory. Although the rate of recurrent nerve paralysis was relatively high even after the suspension of aggressive bilateral recurrent nerve lymph node dissection, and the rate of the progressive disease after the definitive CRT was high, salvage CRT appears to provide some advantages for the patients who would otherwise not have other treatment options following a non-curative and residual operation.

Ionizing radiation, inflammation, and their interactions in colon carcinogenesis in Mlh1-deficient mice

Genetic, physiological and environmental factors are implicated in colorectal carcinogenesis. Mutations in the mutL homolog 1 (MLH1) gene, one of the DNA mismatch repair genes, are a main cause of hereditary colon cancer syndromes such as Lynch syndrome. Long-term chronic inflammation is also a key risk factor, responsible for colitis-associated colorectal cancer; radiation exposure is also known to increase colorectal cancer risk. Here, we studied the effects of radiation exposure on inflammation-induced colon carcinogenesis in DNA mismatch repair-proficient and repair-deficient mice. Male and female Mlh1^−/− and Mlh1^+/+ mice were irradiated with 2 Gy X-rays when aged 2 weeks or 7 weeks and/or were treated with 1% dextran sodium sulfate (DSS) in drinking water for 7 days at 10 weeks old to induce mild inflammatory colitis. No colon tumors developed after X-rays and/or DSS treatment in Mlh1^+/+ mice. Colon tumors developed after DSS treatment alone in Mlh1^−/− mice, and exposure to radiation prior to DSS treatment increased the number of tumors. Histologically, colon tumors in the mice resembled the subtype of well-to-moderately differentiated adenocarcinomas with tumor-infiltrating lymphocytes of human Lynch syndrome. Immunohistochemistry revealed that expression of both p53 and β-catenin and loss of p21 and adenomatosis polyposis coli proteins were observed at the later stages of carcinogenesis, suggesting a course of molecular pathogenesis distinct from typical sporadic or colitis-associated colon cancer in humans. In conclusion, radiation exposure could further increase the risk of colorectal carcinogenesis induced by inflammation under the conditions of Mlh1 deficiency.

Esophageal carcinoma: ex vivo evaluation with diffusion-tensor MR imaging and tractography at 7 T

PURPOSE

To determine the feasibility of diffusion-tensor magnetic resonance (MR) imaging and tractography as a means of evaluating the depth of mural invasion by esophageal carcinomas.

MATERIALS AND METHODS

This study was approved by the institutional review board, and written informed consent was obtained from each patient. Twenty esophageal specimens, each containing a carcinoma, were studied with a 7.0-T MR imaging system equipped with a four-channel phased-array surface coil. Diffusion-tensor MR images were obtained with a field of view of 50-60 mm × 25-30 mm, matrix of 256 × 128, section thickness of 1 mm, b value of 1000 sec/mm(2), and motion-probing gradient in seven noncollinear directions. The MR images were compared with the histopathologic findings as the reference standard. The differences in diffusion-tensor MR imaging parameters between the carcinoma and the layers of the esophageal wall were statistically analyzed by using the Dunnett test.

RESULTS

In all 20 carcinomas (100%), the diffusion-weighted images, apparent diffusion coefficient (ADC) maps, fractional anisotropy (FA) maps, λ1 maps, and direction-encoded color FA maps made it possible to determine the depth of tumor invasion of the esophageal wall that was observed during histopathologic examination. The λ1 maps showed the best contrast between the carcinomas and the layers of the esophageal wall. The carcinomas had both lower ADC values and lower FA values than the normal esophageal wall; thus, the carcinomas were clearly demarcated from the normal esophageal wall. Diffusion-tensor tractography images were also useful for determining the depth of tumor invasion of the esophageal wall.

CONCLUSION

Diffusion-tensor MR imaging and tractography are feasible in esophageal specimens and provide excellent morphologic data for the evaluation of mural invasion by esophageal carcinomas.

Changes in the microvascular structure of mucosal squamous cell carcinoma of the esophagus and their significance in tumor progression

BACKGROUND

To identify the clinical T stage by endoscopy is a major diagnostic goal for superficial esophageal squamous cell carcinoma (ESCC). The completion of a microvascular morphological study of mucosal lesions is necessary to optimize therapy.

MATERIALS AND METHODS

Images of 197 intra-papillary capillary loops (IPCLs) captured by magnified endoscopy from 15 esophagectomy specimens were studied for their morphological features and IPCL dimensions.

RESULTS

The microvascular morphology was classified into four basic major patterns: 1. spiral loop, 2. wide loop (WL), 3. globular (G) and 4. reticular pattern. The microvascular features and dimensions differed according to the depth of tumor invasion. Especially the mean bundle outline (IPCL diameter) showed significant changes as 20.02, 22.32, and 27.08 μm, respectively, for M1, M2 and M3, respectively (M1:M2 P < 0.05, M2:M3 P < 0.01).

CONCLUSIONS

During tumor stage progression, a high-volume blood demand and cancer cell overgrowth to occupy the laminar propria mucosa (LPM) cause obvious elongation, thickening, branching, irregularity and deformity of the IPCL, which were characteristics of M3 lesions. The results of the present study support and can be applied with the current Japanese classification for improving the diagnostic accuracy, especially to differentiate between M2 and M3 lesions based on the endoscopic findings.

Internal pressure of the conduit during endoscopy on the day after esophagectomy

BACKGROUND

In gastrointestinal surgery, anastomosis can result in various complications. Anastomosis is evaluated using classical examinations. The most reliable one is endoscopy, which provides direct information on the anastomosis and conduit. But the influence of endoscopy on anastomosis is uncertain.

METHODS

The internal pressure of a graft during endoscopy was measured in 36 patients who received esophagectomy, by utilizing the decompression tube which was inserted into the graft during operation. We filled the tube with water and measured the maximum water level in a centimeter water column. All examinations were routinely performed on the day after operation, and thin endoscopes were selected for reducing the stress.

RESULTS

The internal pressure before endoscopy ranged from 6 to 20 cm H2O, and during endoscopy ranged from 9 to 27 cm H2O. The difference in the internal conduit pressure in each patient ranged from 1 to 9 cm H2O. There was no increase in complications caused by endoscopy, including anastomotic leakage.

CONCLUSION

This study is the first to report changes in internal pressure due to the endoscope by direct measurement. The pressure gradient observed was below the physiological pressure during swallowing. These results suggest that endoscopy is a safe examination even after surgery.

A pilot trial of S-1 plus irinotecan chemotherapy for esophageal adenocarcinoma

BACKGROUND/AIMS

This study investigated the clinical efficacy and toxicity of the combination chemotherapy using S-1 plus irinotecan for esophageal adenocarcinoma.

METHODOLOGY

This study included 10 patients with histologically confirmed adenocarcinoma of the esophagus or esophagogastric junction between April 2005 and August 2011. S-1 was administered orally at a dose of 80 mg/m²/day from day 1 to 14 and irinotecan was given intravenously on day 1 and 8 at a dose of 80 mg/m².

RESULTS

A total of 65 cycles were administered and the response rate was 62.5%. The 50% progression-free survival period and the 50% overall survival period for all of the patients was 8.4 months and 19.1 months, respectively and 5.9 months and 16.3 months for the 8 patients with unresectable or recurrent tumors, respectively. The 2 patients that received adjuvant chemotherapy demonstrated a prophylactic effect for the post-operative recurrence. On the other hand, this therapy showed no severe non-hematological toxicity and only 20% experienced grade 3 neutropenia. As a result, the treatment regimen could generally be performed in an outpatient basis.

CONCLUSIONS

The combination chemotherapy using S-1 and irinotecan showed tolerable clinical efficacy in terms of the response rate, survival and toxicity for esophageal adenocarcinoma.

Esophageal squamous cell carcinoma developed 11 years after allogeneic bone marrow transplantation for acute lymphatic leukemia

Younger patients (aged <30 years) presenting with esophageal cancer are rare. Bone marrow transplantation offers a curative therapy in patients with malignant and nonmalignant lymphohematopoietic diseases and other disorders. However, one important late complication in transplantation survivors is the development of secondary malignancies including solid tumors. Although some solid cancers have been demonstrated to occur after bone marrow transplantation, only a few cases of esophageal squamous cell carcinoma have thus far been reported. We herein describe the case of a 27-year-old male with esophageal squamous cell carcinoma, who was diagnosed with T-cell-type acute lymphatic leukemia at the age of 12 and relapsed 5 years later. He achieved a second complete remission and underwent bone marrow transplantation at the age of 17. A genetic analysis revealed germ-line lineage-derived chimeric cellular populations of the donor and patient on both the esophageal squamous cell carcinoma and non tumorous portions of the patient's esophageal mucosa with a preponderance of the patient's germ-line lineage-derived cells, suggesting that repopulated donor-derived hemopoietic stem cells in the esophageal epithelia only partially contributed to the carcinogenesis of esophageal squamous cell carcinoma several years after bone marrow transplantation. Multiple events occurring during the course of treatment for primary hematological disorder may play an important role in the development of esophageal squamous cell carcinoma.

[A case of postoperative liver metastasis of esophageal cancer remains in progression free after successfully resected]

A 59-year-old man admitted for upper gastrointestinal endoscopy of the health examination in the middle of October 2005 was diagnosed with advanced lower esophageal cancer. After a precise examination, he received a subtotal esophagectomy followed by three-field lymphadenectomy in the beginning of November 2005. The histopathological diagnosis was well differentiated squamous cell carcinoma (pT3, ie (+), ly2, v2, pIM0, pN3, pStage III). After two courses of systemic chemotherapy so called FP therapy, solitary liver metastasis in S8 area was detected in May 2007. He received additional two courses of FP chemotherapy, but the CT scan revealed that the lesion was progress disease (PD) in December 2007. It seemed to be difficult to reduce the tumor progression by systemic chemotherapy, so S8 semi-segmental lobectomy was performed. After the operation, the patient received the combination chemotherapy with docetaxel and nedaplatin once a week on day 1 for 4 weeks in five courses, but the CT scan revealed the appearance of the recurrence of residual liver and abdominal lymphnodes in January 2009. So a right hepatic lobectomy and lymphadenectomy were performed. The patient also received chemoradiotherapy after the operation, no recurrence of the liver and lymphnodes metastases has been shown. Surgical resection was sometimes seemed to be effective for treating liver metastasis of esophageal cancer, thus indication of operation need to be discussed for accumulation of many liver metastasis of esophageal cancer.

[Effective combination chemotherapy with gemcitabine hydrochloride, S-1 and nedaplatin for recurrent pancreatic cancer--a case report]

A 57-year-old man who had brown urine, jaundice and appetite loss from June 2006 was diagnosed with advanced pancreatic cancer. He received pylorus-preserving pancreatoduodenectomy in July 2006. Liver metastasis in S6 lesion was revealed by abdomen CT and SPIO-MRI in November and December 2006, respectively. Chemotherapy with gemcitabine hydrochloride (GEM) 1,400 mg/body was administered once a week on days 1, 8 and 15 for 4 weeks. At the beginning of this chemotherapy, it seemed to be a stable disease, but abdominal CT revealed a tumor progress in April 2007. So we selected combination chemotherapy with GEM and S-1 as second-line. At first serum CA19-9 was decreased but gradually increased, and the CT scan revealed the tumor progression in the liver and the local recurrence appeared in February 2008. So we selected combination chemotherapy with GEM and nedaplatin as third-line. After 2 months, CT scan revealed no change in tumor size. This combination chemotherapy can be effective in some patients with GEM-refractory pancreatic cancer.

Mild inflammation accelerates colon carcinogenesis in Mlh1-deficient mice

OBJECTIVE

Inflammatory bowel disease, which frequently accompanies silencing of Mlh1, plays a key role in the pathogenesis of colorectal cancer. The interaction between inflammation and mismatch repair deficiency, however, remains unclear. The aim of this study was to determine the effect of inflammation on colorectal carcinogenesis in Mlh1-deficient mice.

METHOD

Inflammatory colitis was induced by treatment with 1% dextran sodium sulfate (DSS) in drinking water for 1 week in Mlh1 knockout (Mlh1(-/-)), Mlh1 heterozygous (Mlh1(+/-)) and wild-type (Mlh1(+/+)) mice at 10 weeks of age. The development of colon tumors was followed for a subsequent 15 weeks and the tumors were analyzed immunohistochemically for the expression and localization of iNOS, beta-catenin and p53.

RESULTS

Male and female Mlh1(-/-) mice with DSS showed a 63 and 44% incidence of tumors, respectively, whereas no tumors were observed in Mlh1(+/-) and Mlh1(+/+) mice. The mice without DSS treatment did not develop any tumors regardless of the genotype. While aberrant expression of beta-catenin was not detected in colonic neoplasms, p53 and iNOS expression was increased in 100 and 77%, respectively. These immunohistochemical changes were consistent with those of human colon cancers associated with ulcerative colitis.

CONCLUSION

Our results indicate that Mlh1 deficiency strongly accelerates colon carcinogenesis when combined with inflammation. Thus the cells with Mlh1 deficiency, either inherently or colitis associated, may be at an increased risk of cancer under inflammatory conditions.

Ikaros is a mutational target for lymphomagenesis in Mlh1-deficient mice

Deficiencies in DNA mismatch repair (MMR) result in replication errors within key tumor suppressor genes or oncogenes, and cause hereditary nonpolyposis colorectal cancer (HNPCC). Hematological malignancy with microsatellite instability is also associated with defective MMR, but little is known about the target genes for MMR. Here we identified Ikaros, a master transcription factor of lymphoid lineage commitment and differentiation, as a mutational target in spontaneous and radiation-induced T-cell lymphomas in Mlh1-deficient mice. Three quarters of lymphomas lacked Ikaros protein expression, which resulted from a frameshift mutation that created a stop codon. Mononucleotide repeat sequences at 1029-1034(C)6 and 1567-1572(G)6 in Ikaros were mutational hot spots with a one-base deletion occurring with a frequency of 45 and 50%, respectively. Point mutations and splicing alterations were also observed. In total, 85% of the lymphomas showed aberrations in Ikaros. The characteristic of Mlh1-deficient lymphomas is harboring of multiple mutations simultaneously in the same tumor, displaying a combination of two frameshift mutations at different repeats, frameshift and point mutations, and/or deletion mutations. This is the first report of Ikaros mutations coupled with Mlh1 deficiency in lymphomagenesis.

Accelerated growth of intestinal tumours after radiation exposure in Mlh1-knockout mice: evaluation of the late effect of radiation on a mouse model of HNPCC

Mlh1-knockout mice have been developed as a useful model of hereditary non-polyposis colorectal cancer (HNPCC). In this study, we analyzed the pathology of gastrointestinal tumours (GIT) in these mice in detail and examined the possible effects of ionizing radiation on the induction of intestinal tumours to evaluate the late response to radiotherapy in HNPCC. Mlh1-/- mice spontaneously developed GIT and thymic lymphomas by 48 weeks. GIT included not only well differentiated adenocarcinomas but also poorly differentiated and mucinous adenocarcinomas, suggesting that this mouse is a good model for HNPCC. In contrast to colon cancers from HNPCC patients, however, carcinomas of Mlh1-/- mice expressed p53 and showed a lack of transforming growth factor (TGF)-betaRII mutation, which resulted in the expression of TGF-betaRII protein. Irradiation of 10-week-old Mlh1-/- mice accelerated GIT development but had little effect at 2 weeks. Mlh1+/- and Mlh1+/+ mice were not susceptible to spontaneous or radiation-induced thymic lymphomas and GIT until 72 weeks after birth. The development and pathology of GIT in Mlh1-/- mice suggest that this mouse is a good model for HNPCC, although tumour-related responsible genes might be different from HNPCC. As X-ray exposure promoted carcinogenesis of GIT in adult Mlh1-/- mice, an increased risk of secondary cancers after radiotherapy for HNPCC patients should be taken into consideration.

Mammary tumorigenesis in ApcMin/+ mice is enhanced by X irradiation with a characteristic age dependence

The Apc(Min/+) (Min) mouse is genetically predisposed to both intestinal and mammary tumorigenesis. We investigated age-related changes in the susceptibility of mice (before, during and after puberty) to radiation-induced mammary tumorigenesis using this model. Female Min and wild-type mice having the C57BL/6J background were irradiated with 2 Gy of X rays at 2, 5, 7 and 10 weeks and killed humanely at 18 weeks of age. Min mice irradiated at 7-10 weeks of age (after puberty) developed mammary tumors with squamous metaplasia, whereas their wild-type littermates did not. Interestingly, irradiation of Min mice at 2-5 weeks (before and during puberty, respectively) did not induce mammary tumors but rather cystic nodules with metaplasia. The mammary tumors exhibited increased nuclear beta-catenin protein and loss of the wild-type Apc allele. Our results show that susceptibility to radiation-induced mammary tumorigenesis increases after puberty in Min mice, suggesting that the tumorigenic effect of ionizing radiation targets the lobular-alveolar progenitor cells, which increase in number with age and are controlled by beta-catenin signaling.

[A case of pyloric or antral malignant stenosis treated with arterial infusion chemotherapy and palliative therapy--self-expandable metal stents through gastrostomy]

The patient is a 62-year-old woman. She had type 3 advanced stomach cancer that was judged to have caused complete stricture of the pylorus, and to be inoperable. She received percutaneous endoscopic gastrostomy (PEG) for decompression. She also received arterial infusion chemotherapy with 5-FU, methotrexate (MTX) and cisplatin (CDDP). As a result, the pylorus stricture was reduced somewhat. We tried a self-expandable metal stent (EMS) after obtaining informed consent. A guide-wire passed in gastrostomy was introduced to the pyloric or antral stenosis manually under x-ray fluoroscopy and endoscopy. Next the EMS was introduced to the position of the stenosis over the positioned guide-wire, and then it was released. The EMS did not migrate after placement and the quantity of meals she could consume was considerably improved. She could take meals for three months after stenting. Bypass procedure is often performed for patients with advanced stomach cancer with pylorus stricture, but we thought we could help the patient maintain a good quality of life (QOL) by pylorus stenting in combination with arterial infusion chemotherapy.

[A patient with small-cell carcinoma of the esophagus with synchronous liver metastasis surviving 48 months after surgery]

Small-cell carcinoma of the esophagus is regarded as having a poor prognosis with frequent and early systemic metastasis. Recently, several reports have described small-cell carcinoma satisfactorily treated by chemotherapy and radiation therapy combined with surgery. We herein report a patient with small-cell carcinoma of esophagus with synchronous multiple liver metastasis who survived 44 months after surgery. A 70-year-old man was found to have a polypoid lesion at the abdominal esophagus by upper gastrointestinal endoscopy. A biopsy specimen of the lower esophagus demonstrated undifferentiated carcinoma of the esophagus. Ultrasonographic investigation demonstrated solitary SOL in the liver. The patient underwent a total gastrectomy and lower esophagectomy by an abdominal approach. As ultrasonographic evaluation during laparotomy revealed multiple liver metastases, a hepatic artery infusion catheter was inserted into the proper hepatic artery. A pathological study of the resected esophagus and a biopsy specimen of the liver revealed undifferentiated cell carcinoma of the esophagus (small-cell type). During hospitalization, hepatic artery infusion therapy (CDDP 20 mg/4 h and 5-FU 750 mg/5 h) was given for 4 days starting on days 14 and 28. After chemotherapy, liver metastasis could not be detected by ultrasonographic investigation. At the outpatient clinic bi-weekly hepatic artery infusion of 5-FU (1,500 mg/body/5 h) was continued for 30 months. The patient is alive 48 months after surgery without any evidence of recurrence.

[Pharmacokinetics of "subselective" arterial infusion chemotherapy]

Arterial infusion chemotherapy is mainly used for lymph node and peritoneal metastases. Generally, it is said that the concentration of a drug in abdominal organs is higher with arterial infusion chemotherapy than that with systemic chemotherapy. In this study, the pharmacokinetics of arterial infusion chemotherapy for a patient who had an arterial infusion port for lymph node metastasis and peritoneal metastasis, and a hepatic arterial infusion port for liver metastasis, was evaluated. Sequential arterial infusion chemotherapy with methotrexate (MTX) and 5-FU was given. One hundred mg of methotrexate (MTX) was infused over 20 minutes into the aorta, followed by 750 mg of 5-FU over 10 minutes 2 hours later. Blood samples from a peripheral vein and hepatic artery were collected at 10, 20 and 125 minutes from the beginning of the arterial infusion chemotherapy. Then the serum concentration of MTX and 5-FU was examined. The serum concentration of MTX in the hepatic artery was 1.4 to 2.3 times higher than that in peripheral venous blood. The serum concentration of 5-FU in the hepatic artery was 4.9 to 6.0 times higher than that in peripheral venous blood. The serum concentration of drug in abdominal organ was higher with arterial infusion chemotherapy than with systemic chemotherapy. It would thus seem that the effect of arterial infusion chemotherapy is higher than that of systemic chemotherapy.

Cell type- and positionally specific regulation of the aldolase P gene expression in rice seedlings

We describe here different regulation of the AldP gene, a nuclear gene encoding chloroplast aldolase, in different tissues and growth ages of rice seedlings. Expression of the AldP gene is mesophyll cell-specific, and increases from the basal to the upper region in each leaf. The gene expression is repressed in the dark-grown leaf blade, but is induced by a short-term-exposure to light, to a level higher than that seen in the normal leaf blade. However, the light-inducibility differs among the tissues, and shows different patterns among leaf positions; i.e., the extent of light-induction is higher in the third leaf blade as compared with the earlier developed second leaf blade. Such positional differences in the regulation are also seen in the leaf sheath. These responses are not accompanied by changes of the cell type specificity in the expression.

Structural analysis of the chloroplastic and cytoplasmic aldolase-encoding genes implicated the occurrence of multiple loci in rice

The genes AldP and AldC-a, encoding the rice chloroplastic (cp) and cytoplasmic (ct) types of aldolase, respectively, were isolated and sequenced, and their transcription start points (tsp) were determined. Organization of the two genes was found to differ greatly; AldP consisted of six exons while AldC-a consisted of two exons. The deduced amino acid (aa) sequence of AldP contained a cp stromal targeting signal, followed by a sequence that matches the experimentally determined N-terminal sequence of mature AldP. The two enzymes share only 55% aa identity. However, rice AldP had about 73% homology with the cp aldolase of spinach. Also, the homology of AldC-a with maize, spinach and Arabidopsis thaliana cytoplasmic aldolases ranged from 70 to 90%. Southern blot analyses indicated that AldP is encoded at a single locus, whereas the gene encoding the ct counterpart is distributed at three loci on the genome. This feature is quite different from those of maize and spinach, in which only one locus was found for the ct aldolase.