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At least 91 records · Page 5Linked to original sources
PubMed2002

Histologic changes in defunctioned rectums in patients with inflammatory bowel disease: a clinicopathologic study of 82 patients with long-term follow-up.

PURPOSE: Inflammation occurs in defunctioned rectums in patients without inflammatory bowel disease. Defunctioned rectums in patients with inflammatory bowel disease have additional histopathologic changes that can cause diagnostic confusion. The aim of this study was to ascertain whether histologic changes in defunctioned rectums had any association with original pathologic diagnosis in the colectomy specimen, duration of defunctionalization, or occurrence of Crohn's disease-like complications during follow-up. METHODS: In this retrospective study, we reviewed the patient records and reexamined histologically the defunctioned rectums and original colectomy specimens of 84 consecutive patients encountered between 1983 and 1986. RESULTS: All excised rectal specimens had ulcers and erosions, usually with prominent mucosal lymphoid aggregates, often with mucosal atrophy, diffuse mucin depletion, and marked mucosal architectural distortion. Transmural lymphoid aggregates were identified in 56 patients (67 percent) and were graded as moderate or marked in 35 (42 percent). Ten rectal specimens contained nonnecrotizing granulomas. The original pathologic diagnoses from the colectomy specimens were as follows: ulcerative colitis (n = 22), Crohn's disease (n = 19), indeterminate colitis (n = 41), adenocarcinoma (n = 1), and diverticular disease (n = 1). Only mild histologic changes were observed in rectal specimens from patients with diverticular disease and adenocarcinoma, and granulomas were identified more frequently in Crohn's disease patients. Otherwise, no feature in the defunctioned rectum was associated with the original diagnosis or duration of defunctionalization. Sixteen patients (19 percent) had late surgical complications suggestive of Crohn's disease (abscess, fistula, or subsequent biopsy specimen containing nonnecrotizing granulomas) after a median follow-up of 4.8 years. Five were patients categorized as having Crohn's disease with colectomy specimen, nine had indeterminate colitis, and two had ulcerative colitis. No histologic feature in the defunctioned rectum was associated with Crohn's disease-like complications. CONCLUSIONS: Granulomas in a defunctioned rectum were associated with an original diagnosis of Crohn's disease. Transmural lymphoid aggregates were common in defunctioned rectums in patients with inflammatory bowel disease and did not indicate Crohn's disease. Other histologic changes developed independently of diagnosis and duration of defunctionalization.

Adolescent↗
PubMedDate not supplied

Development of enkephalin in the rectum and ganglion of Remak of the chick.

Radioimmunoassay (RIA) and high performance liquid chromatography were used in combination with immunocytochemistry to study the development of met-enkephalin (Met-enk) in the rectum and the ganglion of Remak of the chicken. Met-enk was detected by RIA in the rectum at 5 days of incubation (d.i.). The concentration increased from 5-9 d.i. and did not change significantly thereafter. In contrast, the concentration of Met-enk in Remak's ganglion increased throughout the developmental period of study. Met-enk immunoreactivity first appeared in cell bodies in Remak's ganglion at 6 d.i. and in a small number of processes in the wall of the rectum. By 9 d.i., Remak's ganglion contained many immunoreactive cell bodies, some of which extended processes into the wall of the rectum in the region of the myenteric plexus. Varicosities were first seen in the rectum at 13 d.i. and increased in number and staining intensity with developmental age. The fact that immunoreactive cell bodies persist in Remak's ganglion throughout the course of development and send processes into the rectum suggests that a major portion of enkephalinergic innervation of the rectum is extrinsic. On the other hand, the presence of Met-enk immunoreactivity in both nerve cell bodies and processes in rectal explants stripped of Remak's ganglion suggests that this peptide is also contained in intrinsic neurons in the chick rectum.

Animals↗
PubMed2005

Testing the new ICRU 62 'Planning Organ at Risk Volume' concept for the rectum.

BACKGROUND AND PURPOSE: To study the impact of the new ICRU 62 'Planning organ at Risk Volume' (PRV) concept on the relationship between rectum dose-volume histogram (DVH) data and toxicity. PATIENTS AND METHODS: The acute gastro-intestinal (GI) RTOG toxicity in 127 prostate cancer patients prescribed a total dose of 70 Gy with conformal irradiation to either the prostate, the prostate and seminal vesicles or the whole pelvis (initial 50 Gy only) were analysed. DVHs were derived for the rectum only and for rectum extended with six PRV margin sets (narrow/intermediate/wide; anterior/anterior and posterior). The data was analysed using permutation tests, logistic regression and effective uniform dose (EUD) calculations. RESULTS: Acute Grade 2 GI toxicity was seen in 22 of 127 cases (17%). Permutation tests showed that the difference between DVHs for patients with and without Grade 2 effects was significant, both for rectum only and rectum PRVs (P-value range: 0.02-0.04), with generally lower P-values for the PRVs. In the logistic regression, the fractional DVH variables (i.e. volumes) were significantly related to toxicity, with approximately 2-3 times as many significant dose levels for the PRVs as for rectum only. E.g. with wide anterior and posterior margins (16 and 11 mm, respectively) the relation was significant at 26 different dose levels (6-7, 13-14, 35-43, 60-71 and 73 Gy), compared to nine levels (38-40, 43-44 and 71-74 Gy) for rectum only. EUDs were significantly different for patients with and without Grade 2 effects both for rectum only and the PRVs (95% confidence interval for EUD increase with Grade 2 effects: 0.1-3.1 Gy). CONCLUSIONS: All statistical methods applied indicated a small, but definite difference in DVH parameters between patients with versus those without Grade 2 effects. The difference was most pronounced when margins of 16 mm anterior and 11 mm posterior were applied.

Humans↗
PubMed1999

Magnetic stimulation: a novel method for inducing evacuation of the neuropathic rectum and urinary bladder in a canine model.

OBJECTIVES: To study the effect of sacral magnetic stimulation (MS) on the neuropathic rectum and urinary bladder in dogs. It has been demonstrated in a canine model and in humans that sacral MS of both the empty and full rectum effected a significant increase in rectal and vesical pressures. Evacuation of the full rectum, as well as balloon expulsion, were achieved. METHODS: In 15 dogs, bilateral pelvic ganglionectomy was carried out, and rectal and vesical denervation was confirmed by bethanechol and atropine testing. Sacral MS of the empty and full rectum and urinary bladder were performed by means of a magnetic stimulator and coil. The electromyographic (EMG) response of the rectus abdominus muscles to sacral MS was recorded. RESULTS: After pelvic ganglionectomy, the rectal, vesical, anal, and urethral pressures revealed a significant decrease (all P <0.05). On sacral MS of the empty rectum and urinary bladder, rectal and vesical pressures increased (both P <0.001) and anal and urethral pressures did not change (both P >0.05). Atropine injection abolished the rectal and vesical response to sacral MS; bethanechol did not. During sacral MS, no EMG activity of the rectus abdominus muscles was recorded. Intermittent sacral MS of the full rectum and urinary bladder raised rectal and vesical pressures (both P <0.001) and effected evacuation. CONCLUSIONS: Sacral MS causes evacuation of the neuropathic rectum and urinary bladder in a canine model. The technique is simple, noninvasive, nonradiologic, and cost-effective and has no adverse effects. It is suggested that it be used for evacuation of the neuropathic rectum and urinary bladder in patients with spinal cord injury.

Animals↗
PubMed2001

Sensory and biomechanical responses to distension of the normal human rectum and sigmoid colon.

BACKGROUND: Visceral pain is a major clinical problem. The aim of the present study was to compare the pain and biomechanical responses to standardized distension of the human colon. METHODS: The relation between pain intensity and pressure, cross-sectional area (CSA) and tension-strain relations of the rectum and sigmoid colon were studied in 11 normal subjects following standardized distension using impedance planimetry. The bag was inflated stepwise with pressures up to 6 kPa. The subjects, who were blinded for the distension procedure, rated their pain intensity using an aggregate visual analogue score (VAS) combining the intensity of the feeling of air, urge to defecate and pain. RESULTS: The distensions produced an initial rapid increase in CSA followed by a phase of slow increase until a steady state CSA was reached after 0.5-1 min. Several phasic contractions (observed as short-term decreases in the CSA) were recorded in the rectum from the end of the rapid phase to the end of distension at pressures from 1 to 5 kPa. The CSA in the rectum and sigmoid colon was 3,706 +/- 426 mm(2) and 2,305 +/- 426 mm(2) at the maximum bag pressure of 6 kPa (F = 52.4, p < 0.001). The tension-strain relation did not differ between the normal rectum and sigmoid colon. The VAS score for every modality (air, defecation and pain) revealed an increase in intensity as a function of pressure. The VAS score in the rectum and the sigmoid colon as a function of tension and strain did not show any differences. CONCLUSIONS: The biomechanical properties in the sigmoid colon and rectum were alike. For a given wall tension and circumferential strain the sensibility seems equal in the rectum and the sigmoid colon. The observed difference in perception between the two segments was related to the greater CSA in the rectum.

Abdominal Pain↗
PubMed1996

Effects of continuous low-dose-rate brachytherapy on the rectum of the rat.

The dose-limiting factor in essentially all curative radiotherapy is damage to normal tissue. In spite of this, our understanding of radiation-induced damage to normal tissue leaves much to be desired. Damage to the rectum is often observed after clinical brachytherapy of pelvic malignancies. A model in which the rectum of the rat is irradiated with a uniform and reproducible dose of brachytherapy irradiation was developed. This system consists of an intracavitary applicator, which is used in conjunction with methods that reduce fecal flow, a jacket that restrains rat movement and a lead-shielded chamber to contain rats during low-dose-rate brachytherapy. Irradiation was applied in 48-h intervals separated by 48-h breaks during which the applicator was removed. Methods to analyze the sequelae of brachytherapy irradiation of the rectum were also developed. The total dose of 0.75 Gy/h continuous low-dose-rate brachytherapy required to produce obstruction in the rat rectum has been measured. The ED50 was 70.6 +/- 4.2 Gy. The length of time between irradiation and obstruction was also correlated with total dose. Other effects on the rectum that were related to dose were diarrhea and rectovaginal fistula. This irradiation system can produce uniform and reliable brachytherapy doses to the rat rectum. The late effects in normal tissues observed in this model are similar to those observed in humans after irradiation of the rectum. The model should be appropriate for analyzing relative changes in the rectum resulting from different dose rates and fractionation schemes relevant to brachytherapy.

Animals↗
PubMedDate not supplied

Is the rectum a conduit or storage organ?

The rectum is claimed to be a conduit; as it receives the stools, the rectoanal inhibitory reflex is evoked and defecation occurs. However, in many healthy subjects, stools could be palpated in the rectum by digital rectal examination (DRE) without the subject feeling the desire to defecate. The purpose of this communication is to study whether the rectum is a conduit or a storage organ. The study comprised 48 healthy volunteers (mean age 38.4 +/- 15.8 SD years; 30 men, 18 women). Number of stools per week was recorded and DRE was carried out followed by air enema radiography. The subjects had a normal stool frequency of 7.8 +/- 1.4 per week. Most of them last defecated a mean of 6.2 +/- 3.4 hours prior to the test. Stools were palpated in the lower rectum by DRE in 31/48 subjects and by radiography in 12/16. DRE correlated with radiologic examination in 9/12 subjects; in 3 of them, DRE revealed an empty rectum while radiography showed stools in the upper rectum. The 17 subjects with an empty rectum had their last defecation 5.2 +/- 3.6 hours before DRE, and the 31 subjects with palpable stools 15.6 +/- 12.9 hours. In conclusion, the rectum might be considered not simply as a conduit for stools but also as a storage organ. This occurs when it receives from the sigmoid colon an amount of stools too small to evoke the defecation reflex, or when this reflex is neglected due to unfavorable circumstances of defecation.

Adolescent↗
PubMed2001

Air insufflation: a useful adjunct to the single contrast barium enema for the evaluation of the rectum.

We examined whether insufflation of a small volume of air after a single-contrast barium enema would improve evaluation of the rectum. Eighty patients presenting for barium enema by single-contrast technique underwent examination of the colon including spot films with fluoroscopy and palpation during introduction of the barium and filled overhead views, using standard apparatus and technique. The examination was completed by draining barium from the rectum only, following which air in the barium enema bag was squeezed back into the rectum and three views of the rectum obtained (lateral, left posterior oblique, and frontal). Two reviewers then chose the best image of the rectum from each study with relevance to luminal distention and visibility of surface detail of the rectum. Following air insufflation, improved surface detail visualization was recognized by both reviewers in 69 (86%) patients and by one reviewer in 10 (12%) patients, a statistically significant observation (P < 0.0001). There was a trend towards improved rectal distention, recognized by both reviewers in 37 (46%) patients and by one reviewer in 18 cases (22%). In 25 (31%) patients neither reviewer recognized any improvement in rectal distention. Rectal abnormalities were identified in nine cases; there were two large carcinomas, two radiation strictures, two rectal fistulae, two small rectal polyps (5 and 7 mm), and one case of prolapsing rectal mucosa. All rectal abnormalities were visible on the air insufflation views. In the two cases of suspected rectal polyp and one of the cases of rectal fistula, the findings were not visible on the initial barium filled views. A normal rectum was observed in 71 cases. Follow-up of these 71 patients found no later evidence of any rectal abnormalities. Improved filling of the proximal colon following air insufflation was observed in 12 (15%) patients, an additional and unexpected benefit of this maneuver. Air insufflation is a simple addition to the SCBE study that improves visualization of the rectum.

Adult↗
PubMed1991

Smoking and other risk factors associated with the stage and age of diagnosis of colon and rectum cancers.

The present study analyzes data on colon and rectum cancer cases from a population-based cancer registry to determine the effect of smoking, alcohol drinking, and family history of cancer on disease characteristics. A total of 771 cases of primary invasive cancer of the colon and 304 cancers of the rectum constitute the study sample. More advanced colon cancer was present in female smokers than in female nonsmokers, while in males there was no smoking effect on stage at diagnosis of colon cancer. For cancer of the rectum, male smokers had a higher frequency of advanced disease than did nonsmokers. Smoking men and women were found to have lower mean ages at diagnosis of both colon and rectum cancer than did nonsmokers (p less than 0.001 and p less than 0.004, respectively). Alcohol drinking remained consistently associated with lower age at diagnosis in both sexes for both colon and rectum cancer (p less than 0.001 and p less than 0.001, respectively). Those cases of rectum cancer having positive family history for colorectal cancer in their first degree relatives had younger age at diagnosis than those having negative family history (p less than 0.005). The age at diagnosis was progressively younger as the number of risk factors increased (p less than 0.001 for colon cancer and p less than 0.003 for cancer of the rectum). Our findings indicate an interaction between exposures to risk factors that are potentially carcinogenic or cocarcinogenic and manifestations of cancer of the colon and rectum.

Age Factors↗
PubMed1994

[Transanal resection of the rectum].

A new method of an organ-preserving operation for the management of the initial forms of rectal carcinoma and benign tumors of the distal parts of the rectum has been elaborated and successfully used at the Scientific Research Institute of Proctology. It consists in transanal resection of the rectum with creation of a recto-anal anastomosis. Transanal resection of the rectum was performed on 34 patients. Sixteen patients had giant or recurrent villous tumours of the distal part of the rectum 6 of which had undergone malignant degeneration. In a group of 34 patients 14 had the initial forms of carcinoma of the inferoampular part of the rectum, 2 had a deep cystic colitis, and the other 2 patients were operated on for neurilemoma and teratoma. Recurrences were not revealed in patients with benign diseases in follow-up periods of 2 to 8 years. Recurrent carcinoma of the rectum in the region of the anastomosis was found in 2 patients in follow-up periods of 25 to 37 months. They underwent extirpation of the rectum. The new method enables stable recovery to be achieved and saves the patients from crippling abdomino-anal resections and extirpation of the rectum in the management of benign new growths and initial forms of carcinoma of the distal parts of this organ.

Adenoma, Villous↗
PubMed1997

Lymph node metastases detected in the mesorectum distal to carcinoma of the rectum by the clearing method: justification of total mesorectal excision.

BACKGROUND: Total mesorectal excision effectively reduces the local recurrence rate of carcinoma of the rectum. This study was undertaken to clarify the rationale for total mesorectal excision. STUDY DESIGN: We retrospectively reviewed the records of 198 patients who underwent resection of a carcinoma of the rectum. The presence of nodal metastases in the mesorectum distal to the primary tumor was examined by the clearing method. RESULTS: The metastatic rate in the distal mesorectum was 20.2 percent. The metastatic rates according to the extent and site of the tumor were as follows: pT1, 0 percent; pT2, 0 percent; pT3, 21.9 percent; pT4, 50 percent; rectosigmoid, 10 percent; upper rectum, 26.3 percent; and lower rectum, 19.2 percent. The longest distal spread from the primary tumor to the metastatic node was 2 cm in carcinoma of the rectosigmoid, 4 cm in carcinoma of the upper rectum, and 3 cm in carcinoma of the lower rectum. CONCLUSIONS: Total mesorectal excision is required for patients with T3 and T4 tumors in the lower rectum, and excision of all mesorectal tissue down to at least 5 cm below the tumor is required for patients with T3 and T4 tumors in the upper rectum.

Humans↗
PubMed2006

Comparison of extrinsic efferent innervation of guinea pig distal colon and rectum.

The extrinsic efferent innervation of the distal colon and rectum of the guinea pig was compared, by using retrograde tracing combined with immunohistochemistry. Application of the carbocyanine tracer DiI to the rectum filled significantly greater numbers of extrinsic neurons than similar injections into the distal colon. Approximately three-fourths of all filled neurons from either location were either sympathetic or parasympathetic; the rest were spinal sensory neurons. Nerve cell bodies in sympathetic prevertebral ganglia labelled from the two regions were similar in number. Both regions were innervated by sympathetic neurons in paravertebral ganglia; however, the rectum received much more input from this source than the colon. The rectum received significantly more input from pelvic ganglia than the colon. The rectum also received direct innervation from two groups of neurons in the spinal cord. Neurons located in the spinal parasympathetic nucleus in segment S2 and S3 were labelled by DiI injected into the rectal wall. Similar numbers of neurons, located in intermediolateral cell column and dorsal commissural nucleus of lumbar segments, also projected directly to rectum, but not colon. The great majority (>80%) of retrogradely labelled nerve cell bodies in sympathetic ganglia were immunoreactive for tyrosine hydroxylase. In pelvic ganglia, retrogradely labelled neurons contained choline acetyltransferase and/or nitric oxide synthase or tyrosine hydroxylase. Although the rectum and colon in this species are continuous and macroscopically indistinguishable, they have significantly different patterns of extrinsic efferent innervation, presumably reflecting their different functions.

Animals↗
PubMed1994

Ontogeny of the endocrine cells of the intestine and rectum of sea bass (Dicentrarchus labrax L.): an ultrastructural study.

Several endocrine cell types were ultrastructurally characterized during the differentiation of the intestine and rectum of sea bass (Dicentrarchus labrax L.) larvae. Only one cell type (type I) was found in the posterior region of the undifferentiated gut of 5-day-old larvae (phase I). Types V and VI were found in both the intestine and rectum, types II, III and IV in the intestine, and types VII and VIII in the rectum of 9- and 12-day-old larvae (phase II), the rectum alone showing signs of functional differentiation. In phase III larvae, in which both the intestine and rectum were differentiated, types IX, X, XI, XII, XIII, XIV and XV were found in the intestine, only types X, XI and XII being seen in the rectum. Besides these, a new cell type, XVI, was observed in the intestine of 55- and 60-day-old larvae (phase IV), in which the digestive tract was completely differentiated. The endocrine cells appearing in phases I and II showed very scarce secretory granules and the ultrastructural features of undifferentiated cells. Some endocrine cell types in the earliest developmental stages were related to some of those found later. A maturational process of the endocrine cell types paralleled the differentiation of the intestine and rectum, with an apparent increase in the number of secretory granules accompanying organelle development.

Age Factors↗
PubMed2004

Anatomic variations due to radical prostatectomy. Impact on target volume definition and dose-volume parameters of rectum and bladder.

BACKGROUND AND PURPOSE: A quantitative estimate of the impact of prostatectomy on pelvic anatomy is unavailable, even if it would be an important prerequisite for a precise definition of clinical target volume (CTV) in post-prostatectomy radiotherapy. The purpose of this study was to investigate the impact of prostatectomy on the definition of CTV, on the position of bladder and rectum and their implications for three-dimensional conformal radiotherapy (3-D CRT). PATIENTS AND METHODS: Six patients eligible for radical retropubic prostatectomy were considered. Each patient underwent a planning CT between 1 week and 1 month before surgery (CTpre), and then CT was repeated in the same positioning 1-2 months after surgery (CTpost). For each patient the CT(pre/post) scans were matched; rectum, bladder and CTV were contoured on both CT scans for each patient by one observer. Two different CTVs were contoured: CTV1: prostate + seminal vesicles in CTpre; prostate + seminal vesicles surgical bed in CTpost; CTV2: prostate in CTpre; prostate surgical bed in CT(post). After image registration, the contours of rectum, bladder and CTV1/2 drawn on CTpost were transferred on CTpre. The corresponding planning target volumes (PTVs) were generated, and for each PTV, a conformal four field technique using 18-MV X-rays was planned. The volumes of CTV1, CTV2, PTV1, PTV2, rectum and bladder pre- and post-surgery were compared. Differences in 3-D position of these structures before and after surgery were analyzed by beam's eye view (BEV) images. Pre- and post-surgery dose-volume histograms (DVHs) of rectum and bladder were compared together with the fraction of rectum/bladder receiving at least 95% of the ICRU dose (V95), the treated volume (TV, body included in the 95% isodose) and the irradiated volume (IV, body included in the 50% isodose). RESULTS: For both CTV1 and CTV2, the volumes were significantly reduced after prostatectomy (average reduction around 30 cm3 for both; range 0-60 cm3). This reduction was mainly due to a more caudal definition of the cranial edge of CTV after prostatectomy (average difference for CTV2: 1.5 cm; range 0-2.5 cm). Concerning the bladder, a systematic posterior shift of the bladder base (average: 1.5 cm) was found and was correlated with a significant reduction of V95 for bladder (around 10 cm3; p = 0.03). V95 of the rectum, TV and IV also resulted to be significantly lower after surgery. The average reduction of V95 for the rectum was relatively small (2.5 cm3 of rectal wall). CONCLUSION: The impact of prostatectomy on CTV definition is high. A significant reduction of CTV, PTV, TV and IV may be expected after surgery with a consequent reduction of the portions of rectum/bladder irradiated with adjuvant radiotherapy.

Aged↗
PubMedDate not supplied

A new method for study of the rectum using transvaginal ultrasound with water enema.

BACKGROUND: To propose a new method for the ultrasound study of the rectum. METHODS: Twenty-one healthy female patients, 58-72 years old, were examined. To achieve optimal filling and distention of the rectum, the examination was performed with the patient in the right lateral decubitus position. After placing the probe into the vagina, 1000-1500 mL of water warmed to 35 degrees C was introduced into the rectum through a cannula. After the rectum was completely full, the cannula was extracted. Images were obtained before and after rectum distention on the transverse plane by using a 5.0-MHz convex radial endocavitary probe. RESULTS: Using water eliminated air and fecal artifacts, so rectal wall layers were reliably demonstrated, with the rectal ampulla well distended. In addition, the rectum in whole circumferential extension and the perirectum fat were clearly visualized. CONCLUSION: This new method is useful for study of the rectum.

Adipose Tissue↗
PubMed1994

Distribution of extrinsic enkephalin-containing nerve fibers in the rat rectum and their origin in the major pelvic ganglion.

The distribution of nerve fibers containing enkephalin (ENK)-like immunoreactivity was examined in the rectum of aganglionosis rats (AGRs) which completely lack the intramural ganglion cells in the large intestine, and was compared with that of their normal littermates. Furthermore, Met5-enkephalin-Arg6-Gly7-Leu8 (MEAGL)-like immunoreactive neurons projecting to the rectum were examined using retrograde tracing combined with immunohistochemistry in the major pelvic ganglion of normal male rats. In the intermuscular space of the aganglionic rectum of AGRs, unlike the pattern of the normal intermuscular plexus, moderate numbers of ENK-like-immunoreactive fibers were arranged in an irregular, coarse network; greatly diminished numbers of immunoreactive fibers were found in the submucosa. No ENK-like-immunoreactive fibers were seen in the circular muscle layer and mucosa. In the normal rat rectum, ENK-like-immunoreactive fibers were seen throughout all layers, and immunoreactive nerve cells were found predominantly in the myenteric plexus of colchicine-treated animals. Fluoro-Gold injected into the upper rectum labelled numerous principal ganglion neurons in the major pelvic and inferior mesenteric ganglia. Less than 10% of tracer-labelled neurons were positive for fluorescein immunolabelling of MEAGL in the major pelvic ganglion; no immunoreactive neurons were found in the inferior mesenteric ganglion. In the major pelvic ganglion of the colchicine-treated normal rats, about 5% of principal ganglion neurons were immunoreactive for MEAGL. Comparison of serial paraffin sections of the major pelvic ganglion stained for tyrosine hydroxylase (TH), MEAGL and vasoactive intestinal polypeptide (VIP), respectively, revealed that more than half of MEAGL-like immunoreactive neurons were also positive for TH; there was no case showing co-existence of MEAGL with VIP in the principal neurons. These results indicate that a small number of enkephalin-containing neurons in the major pelvic ganglion project to the rectum, and that more than half of these neurons are postganglionic sympathetic. They may terminate mainly in the myenteric ganglia in the rectum.

Animals↗
PubMed1992

Development of a shielded 241Am applicator for continuous low dose rate irradiation of rat rectum.

This paper describes the development of sources, applicators, and techniques that can be used to irradiate rat rectums with continuous irradiation at dose rates of interest in brachytherapy, either with the full circumference of the rectum irradiated, or with half of the circumference shielded from the radiation. The system uses encapsulated 241Am sources, to irradiate rat rectum with 60 keV photons continuously at a dose rate of up to 50 cGy/hr. Details of the design and fabrication of the 241Am sources, the rectal applicator, the dosimetry of the system, and the protocols for preparing and irradiating the rats, and for detecting early rectal injury using histological examination of irradiated rectum are presented. Highly effective shielding (attenuation factors as low as 0.04) of half of the circumference of the rat rectum was achievable. Unidirectional 241Am irradiators for intracavitary brachytherapy offer a unique tool for examining the effects of shielding a portion of the circumference of the rat rectum, on the radiation tolerance of the rectum.

Americium↗
PubMed2005

A three-dimensional computed tomography-assisted Monte Carlo evaluation of ovoid shielding on the dose to the bladder and rectum in intracavitary radiotherapy for cervical cancer.

PURPOSE: To determine the effects of Fletcher Suit Delclos ovoid shielding on dose to the bladder and rectum during intracavitary radiotherapy for cervical cancer. METHODS AND MATERIALS: The Monte Carlo method was used to calculate the dose in 12 patients receiving low-dose-rate intracavitary radiotherapy with both shielded and unshielded ovoids. Cumulative dose-difference surface histograms were computed for the bladder and rectum. Doses to the 2-cm(3) and 5-cm(3) volumes of highest dose were computed for the bladder and rectum with and without shielding. RESULTS: Shielding affected dose to the 2-cm(3) and 5-cm(3) volumes of highest dose for the rectum (10.1% and 11.1% differences, respectively). Shielding did not have a major impact on the dose to the 2-cm(3) and 5-cm(3) volumes of highest dose for the bladder. The average dose reduction to 5% of the surface area of the bladder was 53 cGy. Reductions as large as 150 cGy were observed to 5% of the surface area of the bladder. The average dose reduction to 5% of the surface area of the rectum was 195 cGy. Reductions as large as 405 cGy were observed to 5% of the surface area of the rectum. CONCLUSIONS: Our data suggest that the ovoid shields can greatly reduce the radiation dose delivered to the rectum. We did not find the same degree of effect on the dose to the bladder. To calculate the dose accurately, however, the ovoid shields must be included in the dose model.

Female↗