Shifting concepts in rectal cancer management: a review of contemporary primary rectal cancer treatment strategies

The management of rectal cancer has transformed over the last 3 decades and continues to evolve. Some of these changes parallel progress made with other cancers: refinement of surgical technique to improve organ preservation, selective use of neoadjuvant (and adjuvant) therapy, and emergence of criteria suggesting a role for individually tailored therapy. Other changes are driven by fairly unique issues including functional considerations, rectal anatomic features, and surgical technical issues. Further complexity is due to the variety of staging modalities (each with its own limitations), neoadjuvant treatment alternatives, and competing strategies for sequencing multimodal treatment even for nonmetastatic disease. Importantly, observations of tumor response made in the era of neoadjuvant therapy are reshaping some traditionally held concepts about tumor behavior. Frameworks for prioritizing and integrating complex data can help to formulate treatment plans for patients.

Impaired adaptation of gastrointestinal motility following chronic stress in maternally separated rats

Exposure to early life stress causes increased stress responsiveness and permanent changes in the central nervous system. We recently showed that delayed gastric emptying (GE) and accelerated colonic transit (CT) in response to acute restraint stress (ARS) were completely restored following chronic homotypic stress (CHS) in rats via upregulation of hypothalamic oxytocin (OXT) expression. However, it is unknown whether early life stress affects hypothalamic OXT circuits and gastrointestinal motor function. Neonatal rats were subjected to maternal separation (MS) for 180 min/day for 2 wk. Anxiety-like behaviors were evaluated by the elevated-plus-maze test. GE and CT were measured under nonstressed (NS), ARS, and CHS conditions. Expression of corticotropin-releasing factor (CRF) and OXT in the paraventricular nucleus (PVN) of the hypothalamus was evaluated by real time RT-PCR and immunohistochemistry. MS increased anxiety-like behaviors. ARS delayed GE and accelerated CT in control and MS rats. After CHS, delayed GE and accelerated CT were restored in control, but not MS, rats. CRF mRNA expression was significantly increased in response to ARS in control and MS rats. Increased CRF mRNA expression was still observed following CHS in MS, but not control, rats. In response to CHS, OXT mRNA expression was significantly increased in control, but not MS, rats. The number of OXT-immunoreactive cells was increased following CHS in the magnocellular part of the PVN in control, but not MS, rats. MS impairs the adaptation response of gastrointestinal motility following CHS. The mechanism of the impaired adaptation involves downregulation of OXT and upregulation of CRF in the hypothalamus in MS rats.

Pure NOTES sigmoid resection in an animal survival model

INTRODUCTION

The potential to use single-site transluminal access to perform major surgical procedures is limited. In the current study, a pure natural orifice transluminal endoscopic surgery (NOTES) technique was developed for sigmoid resection, with combined transgastric and transvaginal access to the abdominal cavity and assisted by colonoscopy.

METHODS

This experimental study was conducted on a porcine model. Transgastric access was achieved by needle-knife incision and balloon dilation. Colonoscopy was used to maneuver the colon and expose the colic mesentery. Mesocolic dissection close to the bowel was carried out gastroscopically using a coagulating forceps. To prepare the anastomosis, a circular stapler anvil was introduced endoluminally. Subsequently, sigmoid resection was performed using a roticulating linear stapler inserted transvaginally. Bowel extraction was performed by invagination transrectally. After extracorporeal distal linear stapling of the sigmoid, colorectal anastomosis was completed by application of a circular stapling device transrectally. Gastric access closure was achieved using the over-the-scope clipping system (OTSC).

RESULTS

The procedure was successful in all animals, with the operation time ranging from 150 to 270 minutes. The first animal died at postoperative day 5 from peritonitis due to an infected hematoma following spleen injury by an observation trocar. All other animals gained weight postoperatively. Animals were sacrificed after postoperative day 35. The work-up showed complete anastomotic healing and healed gastric closure. The OTSC clip was still in situ in all animals.

CONCLUSION

The presented study shows that pure NOTES resection and anastomosis of the large bowel are feasible. Intraluminal organ manipulation provided excellent organ exposition and rendered one additional access site unnecessary. Transgastric preparation was shown to be safe and effective.

Up-regulated cystic fibrosis transmembrane conductance regulator after anal stenosis in rats

BACKGROUND

The pathophysiology of fecal incontinence from fecal impaction and rectal distension is poorly understood. We hypothesize that fecal impaction elicits up-regulation of cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated mucosal chloride channel.

METHODS

The anus was ligated to produce 75% stenosis in rats. Controls received ligation without inducing stenosis. 24 to 48 hours after ligation the colon was removed. Mucosal short-circuit current was measured by Ussing chamber. Western blot analysis was used to detect CFTR expression in the colonic mucosa. Ligated rats failed to defecate, whereas control rats stooled normally.

RESULTS

Ligated colons were markedly stool filled and dilated. Water content of feces was significantly increased to 66.5% ± 1.1% (P < .01, n = 12) 24 hours after ligation, vs controls (49.5 ± 5.2%, n = 12). Baseline short-circuit current was significantly increased in the distal (78.8 ± 7.4 μA/cm(2), n = 8, P < .01) and mid colon (24.5 ± 2.5 μA/cm(2), n = 8, P < .05) 24 hours after ligation, compared to control rats (12.5 ± 3.2 μA/cm2, n = 8). CFTR expression was significantly increased 24 hours after ligation in the mid and distal colon.

CONCLUSION

We observe that fecal impaction from anal ligation induces early compensatory up-regulation of CFTR, altering function from net absorption to net secretion in the mid and distal colon.

Hypothalamic circuit regulating colonic transit following chronic stress in rats

Although acute stress accelerates colonic transit, the effect of chronic stress on colonic transit remains unclear. In this study, rats received repeated restraint stress (chronic homotypic stress) or various types of stress (chronic heterotypic stress) for 5 and 7 days, respectively. Vehicle saline, oxytocin (OXT), OXT receptor antagonist or corticotropin-releasing factor (CRF) receptor antagonists were administered by intracerebroventricular (ICV) injection prior to restraint stress for 90 min. Immediately after the stress exposure, the entire colon was removed and the geometric center (GC) of Na51CrO4 (a nonabsorbable radioactive marker; 0.5 μCi) distribution was calculated to measure the transit. Gene expression of OXT and CRF in the paraventricular nucleus (PVN) was evaluated by in situ hybridization. Accelerated colonic transit with the acute stressor was no longer observed following chronic homotypic stress. This restored colonic transit was reversed by ICV injection of an OXT antagonist. In contrast, chronic heterotypic stress significantly accelerated colonic transit, which was attenuated by ICV injection of OXT and by a CRF receptor 1 antagonist. OXT mRNA expression in the PVN was significantly increased following chronic homotypic stress, but not chronic heterotypic stress. However, CRF mRNA expression in the PVN was significantly increased following acute and chronic heterotypic stress, but not chronic homotypic stress. These results indicate that central OXT and CRF play a pivotal role in mediating the colonic dysmotility following chronic stress in rats.

Central and peripheral release of oxytocin following chronic homotypic stress in rats

Accumulation of continuous life stress (chronic stress) often causes gastric symptoms. Centrally released oxytocin has anxiolytic and anti-stress effects. We have recently shown that impaired gastric and colonic motility observed in acute restraint stress was restored following repeated restraint stress for 5 consecutive days (chronic homotypic stress) in mice and rats. Chronic homotypic stress upregulates oxytocin mRNA expression and downregulates corticotrophin-releasing factor (CRF) mRNA expression at the hypothalamus. However, it still remains unclear whether stress responses induced by chronic homotypic stress are accompanied by the central or peripheral release of oxytocin. Adult male SD rats were chronically implanted with microdialysis probes at the hypothalamic paraventricular nucleus (PVN) and jugular vein catheters. Microdialysis and blood sampling were performed following 1st, 3rd and 5th of chronic homotypic stress. Oxytocin levels in the dialysates and plasma were measured by radioimmunoassay (RIA). On day 1 of chronic homotypic stress, oxytocin release was slightly, but not significantly, increased in the PVN and plasma. Oxytocin release was significantly increased in the PVN on day 3 (12.7 ± 1.3 pg/sample, n=5, P<0.05) and day 5 (28.2 ± 2.4 pg/sample, n=5, P<0.05) from basal (6.9 ± 1.8 pg/sample, n=5). In contrast, there were no significant changes observed in the plasma on day 3 and day 5. This suggests that central, but not peripheral, release of oxytocin plays an important role in response to chronic homotypic stress in rats.

[Minimally invasive gastric surgery]

The interest in minimally invasive surgery (MIS) for the treatment of gastric carcinoma has increased in recent years worldwide. In particular, for early gastric carcinoma (EGC) many retrospective comparative trials and some prospective randomized trials have confirmed that laparoscopy-assisted distal gastrectomy shows a better short-term outcome in terms of lower morbidity, less pain, faster recovery and shorter hospital stay in contrast to open surgery. In this group of selected patients MIS is safe and feasible but at present not widely accepted because of a limited evaluation in oncologic long-term follow-up. In cases of EGC limited to the mucosal layer and under the condition that endoscopic resection is not suitable, laparoscopic local wedge resection or intragastric resection can be an alternative option with good results in long-term follow-up. The data for laparoscopic total gastrectomy and MIS for advanced gastric cancer have confirmed that both are technically feasible and extended lymph node dissection can also be laparoscopically performed. However, laparoscopic total gastrectomy is much more complex and even in expert hands more complications and a higher morbidity have been observed in contrast to laparoscopic distal resections.

Akute Hemiparese und ipsilaterales Horner-Syndrom – Eindeutige Indikation zur intravenösen Thrombolyse?

Die Symptomtrias „akute Hemiparese, ipsilaterales Horner-Syndrom (v. a. Miosis und Ptosis) und Nackenschmerzen“ gilt als typisches Syndrom eines spinalen Infarktes bei akutem Verschluss einer Vertebralarterie (Opalski-Syndrom). Gleichermaßen kann ein spontanes zervikales epidurales Hämatom mit unilateraler Kompression des zervikalen Myelons (Brown-Séquard-Syndrom) zu dieser Symptomtrias führen. Die akuten Therapieoptionen sind divergent (rekanalisierende Therapie vs. operative Entlastung). Eine korrekte Diagnosestellung kann in der Akutphase schwierig sein, insbesondere wenn klinisch die Hemiparese im Vordergrund steht. Der vorgestellte Fall soll auf diese wichtige Differenzialdiagnose aufmerksam machen und Orientierungshilfen im Akutmanagement geben.

How low is low? Evolving approaches to sphincter-sparing resection techniques

Although advances in rectal cancer staging may ultimately be accurate enough to reliably exclude disease outside the rectal wall (thereby allowing local approaches to be more widely and safely applied) and advances in the use of neoadjuvant chemo- and radiation therapy may ultimately produce more "complete responders" that can be accurately identified and spared surgery altogether, as it stands, radical resection forms the basis of curative treatment for rectal cancer. However, the concepts that guide the surgeon in choosing the optimal approach in radical resection are changing. In the past, the decision as to how to proceed surgically with radical resection was based primarily on the level of the tumor above the anal verge or anorectal ring. The issue was primarily "How low is the tumor?" and "Is the distal margin safe?" A more modern approach focuses attention on achieving a negative circumferential margin despite what historically may seem to be a very minimal distal margin, the current issue is not "How low is the tumor?" so much as it is "How deep does the tumor go?". This shift in focus has been a major impetus in the evolution of sphincter sparing resection techniques.

Cervical Follicular Dendritic Cell Sarcoma: A Case Report and Review of the Literature

Follicular dendritic cell (FDC) sarcoma is a rare tumour with a low-to-intermediate grade of malignancy. It frequently occurs in cervical, mediastinal and axillary lymph nodes. In approximately 30% of cases an extranodal localization has been reported (tonsils, oral cavity, mediastinum, liver, and spleen). Very little is known about possible treatment options and overall prognosis. This case reports a 66 year-old patient, who underwent surgical removal of a persistently enlarged right cervical lymph node. The histopathological examination revealed a spindle cell tumour with lymphocyte and plasma cell infiltrates. Neoplastic cells stained positive for CD21, CD23 and CD35, thus confirming the diagnosis of FDC sarcoma. The neoplasm recurred two years later and partial regression was achieved by IGEV rescue therapy. We briefly discuss clinical history, histopathological differential diagnosis and treatment options of FDC sarcoma.

Food intake and interdigestive gastrointestinal motility in ghrelin receptor mutant rats

BACKGROUND

Ghrelin is the endogenous ligand for the growth hormone secretagogue receptor (GHSR). Ghrelin regulates feeding activity and interdigestive contractions of the stomach in rodents. To investigate the role of endogenous ghrelin in the digestive system, we have developed GHSR-mutant rats, named FHH-Ghsr(m1Mcwi), using the Fawn-Hooded Hypertensive (FHH) parental strain.

METHODS

N-ethyl-N-nitrosourea (ENU) was used as a mutagen. Genomic DNA prepared from a tail clip was analyzed using the targeting induced local lesions in genomes (TILLING) approach. The non-synonymous mutation in position 343 (NM_032075) led to the generation of a premature stop codon, causing deletion of the last 22 amino acids at the C-terminal of ghrelin receptor protein. Spontaneous and ghrelin-stimulated food intake was measured in wild-type (WT) FHH and FHH-Ghsr(m1Mcwi) rats. For interdigestive motility recording, two strain gauge transducers were sutured on the antrum and duodenum. Spontaneous gastroduodenal contractions were recorded in freely moving conscious rats.

RESULTS

Ghrelin (40 μg/kg) failed to stimulate food intake in the mutant rats, while spontaneous food intake was not significantly different between the WT rats and FHH-Ghsr(m1Mcwi) rats. Phase III-like contractions were observed in stomach and duodenum both in the WT and FHH-Ghsr(m1Mcwi) rats. In the WT rats, ghrelin (12 μg/kg) administration enhanced spontaneous phase III-like contractions, and a GHSR antagonist, (D-lys3)GHRP-6 (0.28 mg/kg), abolished the spontaneous phase III-like contractions. In FHH-Ghsr(m1Mcwi) rats, ghrelin and (D-lys3)GHRP-6 did not affect phase III-like contractions.

CONCLUSIONS

It is suggested that the intact GHSR structure is essential for the ghrelin-dependent regulation of interdigestive motility and feeding behavior. Even in FHH-Ghsr(m1Mcwi) rats, spontaneous gastric phase III-like contractions were still observed, suggesting the development of a compensatory mechanism to maintain these contractions.

Sustained delayed gastric emptying during repeated restraint stress in oxytocin knockout mice

We have recently shown that impaired gastric motility observed in acute restraint stress was restored following repeated restraint stress in mice. Repeated restraint stress up-regulates oxytocin mRNA expression and down-regulates corticotrophin-releasing factor (CRF) mRNA expression at the hypothalamus. Oxytocin knockout mice (OXT-KO) have been widely used to study the central oxytocin signalling pathways in response to various stressors. We studied the effects of acute and repeated restraint stress on solid gastric emptying and hypothalamic CRF mRNA expression in wild-type (WT) and OXT-KO mice. Heterozygous (HZ) parents (B6; 129S-Oxt(tm1Wsy)/J mice) were bred in our animal facility. Male OXT-KO, WT and HZ littermates were used for the study. Solid gastric emptying was measured following acute restraint stress (for 90 min) or repeated restraint stress (for five consecutive days). Expression of CRF mRNA in the paraventricular nucleus (PVN) was measured by real-time reverse transcriptase-polymerase chain reaction. There were no significant differences of gastric emptying in WT (68.4 ± 4.1%, n = 6), HZ (71.8 ± 3.1%, n = 6) and OXT-KO (70.6 ± 3.1%, n = 6) mice in nonstressed conditions. Acute stress significantly delayed gastric emptying in OXT-KO mice (33.10 ± 2.5%, n = 6) WT (39.1 ± 1.1%, n = 6) and HZ mice (35.8 ± 1.2%, n = 6). Following repeated restraint stress loading, gastric emptying was significantly restored in WT (68.3 ± 4.5%, n = 6) and HZ mice (63.1 ± 2.6%, n = 6). By contrast, gastric emptying was still delayed in OXT-KO mice (34.7 ± 1.3%, n = 6) following repeated restraint stress. The increase in CRF mRNA expression at the PVN was much pronounced in OXT-KO mice compared to WT or HZ mice following repeated restraint stress. These findings suggest that central oxytocin plays a pivotal role in mediating the adaptation mechanism following repeated restraint stress in mice.

Central orexin-A increases gastric motility in rats

Orexin receptor type-1 (OX1R) is expressed in the dorsal motor nucleus of vagi (DMV). Although orexin-A (OXA) plays an important role in mediating stress responses, it remains unclear how central OXA regulates gastric dysmotility induced by stress. Acute restraint stress (ARS) delays solid gastric emptying via the central corticotropin releasing factor (CRF) and peripheral autonomic neural pathways. We have previously shown that ARS impairs postprandial antro-pyloric coordination and delays solid gastric emptying in rats. We also showed that postprandial gastric contractions were augmented in response to ARS in rats. However, the mechanism of augmented postprandial gastric contractions induced by ARS remains unclear. We tested the hypothesis that augmented gastric motility induced by ARS is mediated via the central OX1R. We also assessed the role of endogenous OXA in the mediation of gastric motility under non-stressed conditions in conscious rats. A strain gauge transducer was implanted on the antrum to record postprandial gastric motility. To investigate whether endogenous OXA is involved in ARS-induced augmented gastric motility, selective OX1R antagonist, SB-334867 (16 μg), was administered intracerebroventricularly (icv). Icv-injection of SB-334867 abolished the augmented gastric contractions induced by ARS. Spontaneous postprandial gastric motility was enhanced by icv-injection of OXA (10 μg), while it was attenuated by icv-injection of SB-3334867. It is suggested that central OXA mediates augmented gastric motility induced by ARS in rats. Central OXA also modulates postprandial gastric contractions in non-stressed conditions.

Hypothalamic oxytocin mediates adaptation mechanism against chronic stress in rats

Accumulation of continuous life stress (chronic stress) often causes gastric symptoms. Although central oxytocin has antistress effects, the role of central oxytocin in stress-induced gastric dysmotility remains unknown. Solid gastric emptying was measured in rats receiving acute restraint stress, 5 consecutive days of repeated restraint stress (chronic homotypic stress), and 7 consecutive days of varying types of stress (chronic heterotypic stress). Oxytocin and oxytocin receptor antagonist were administered intracerebroventricularly (icv). Expression of corticotropin-releasing factor (CRF) mRNA and oxytocin mRNA in the paraventricular nucleus (PVN) of the hypothalamus was evaluated by real-time RT-PCR. The changes of oxytocinergic neurons in the PVN were evaluated by immunohistochemistry. Acute stress delayed gastric emptying, and the delayed gastric emptying was completely restored after 5 consecutive days of chronic homotypic stress. In contrast, delayed gastric emptying persisted following chronic heterotypic stress. The restored gastric emptying following chronic homotypic stress was antagonized by icv injection of an oxytocin antagonist. Icv injection of oxytocin restored delayed gastric emptying induced by chronic heterotypic stress. CRF mRNA expression, which was significantly increased in response to acute stress and chronic heterotypic stress, returned to the basal levels following chronic homotypic stress. In contrast, oxytocin mRNA expression was significantly increased following chronic homotypic stress. The number of oxytocin-immunoreactive cells was increased following chronic homotypic stress at the magnocellular part of the PVN. Icv injection of oxytocin reduced CRF mRNA expression induced by acute stress and chronic heterotypic stress. It is suggested that the adaptation mechanism to chronic stress may involve the upregulation of oxytocin expression in the hypothalamus, which in turn attenuates CRF expression.

Central oxytocin attenuates augmented gastric postprandial motility induced by restraint stress in rats

Restraint stress delays gastric emptying via uncoordinated motility pattern in rats. Central oxytocin has anxiolytic effects and attenuates the hypothalamic-pituitary-adrenal (HPA) axis in response to stress and facilitates stress-induced delayed gastric emptying. However, the role of central oxytocin in regulating gastric motility remains unknown. Postprandial gastric motility was recorded via a strain-gauge transducer, implanted on the antrum in Sprague-Dawley (SD) rats. To investigate whether central and peripheral oxytocin are involved in gastric motility, oxytocin (10 microg) was administered intracerebroventricularly (icv) and intraperitoneally (ip). Central and peripheral oxytocin administration did not affect the postprandial gastric motility under non-stressed conditions. Restraint stress augmented gastric contractions. Central administration of oxytocin, but not peripheral administration, abolished the augmented postprandial gastric contractions induced by restraint stress. Oxytocin facilitates stress-induced delayed gastric emptying via alleviating uncoordinated gastric motility. Oxytocin might be a candidate for the treatment of stress-induced GI motility disorders.

Beneficial effects of social attachment to overcome daily stress

Accumulation of daily life stress (chronic stress) often causes functional gastrointestinal diseases. Central oxytocin plays an important role in attenuating stress responses and regulating positive social interactions. Adult male rats were either paired or singly housed 1 week prior to the stress loading. Solid gastric emptying was measured after 7 consecutive days of chronic heterotypic stress. To study whether endogenous oxytocin is involved in restoring the delayed gastric emptying after paired housing, an oxytocin antagonist was injected intracerebroventricularly (icv) before the gastric emptying study. CRF and oxytocin mRNA expression in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) was evaluated by real time RT-PCR. In singly housed rats, chronic heterotypic stress significantly delayed gastric emptying (35.1+/-2.8%, n=6, P<or=0.01), compared to that of non-stressed rats (53.2+/-1.3%, n=6). Delayed gastric emptying observed in singly housed rats induced by chronic heterotypic stress was significantly improved by paired housing (54.8+/-3.5%, n=8, P<0.05). Central-administration of oxytocin antagonist attenuated the restored gastric emptying in paired housed rats (33.2+/-4.1%, n=6) following chronic heterotypic stress. Increased CRF mRNA expression at the PVN and SON observed in singly housed rats was significantly reduced in paired housed rats following chronic heterotypic stress. In contrast, oxytocin mRNA expression at the PVN and SON was significantly increased in paired housed rats. Social attachment restores delayed gastric emptying following chronic heterotypic stress, via down-regulating CRF expression and up-regulating oxytocin mRNA expression. Our study may provide the scientific benefit of social attachment in our daily life.