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Biomedical subjects

R J Spencer

Publications and source records attributed to R J Spencer.

At least 19 recordsLinked to original sources
PubMed1996

A rat model of infection by Salmonella typhimurium or Salm. enteritidis.

Salmonellosis in the rat has many similarities with the disease in humans, with the ileum thought to be the main site of colonization/invasion in both species. Thus, the rat may be a useful way to study the mechanism of infection by these pathogenic bacteria. A series of infection trials carried out with Hooded Lister rats showed that a salmonella infection persisted for an extended period of time and that salmonellae bind to the small intestinal epithelium as early as 4 h after intragastric intubation. Reinfection from the large intestine may not therefore initially play a significant role in the salmonella infection process. The rat model may therefore provide a means to test in vivo interventionist strategies, designed to block binding of the pathogens in the gastrointestinal tract.

Animals↗
PubMed1995

Trends in colorectal cancer over a half century in Rochester, Minnesota, 1940 to 1989.

Recent reports of increasing incidence, especially in men, led us to update through 1989 an earlier study of colorectal cancer incidence in Rochester that covered the period 1940 through 1979. The combined data reflected cancer trends in the community over half a century. Data resources of the Rochester Epidemiology Project were used to identify new cases of colon and rectal cancer among Rochester residents. Incidence rates were estimated using decennial census data, and 95% confidence intervals were based on the Poisson distribution. The GLIM statistical package was used to evaluate trends over time. Age-adjusted (US white 1970) incidence rates of colorectal cancer for men were 53.7, 61.3, 53.7, 54.2, and 52.5 per 100,000 person-years, respectively, for the decades 1940 to 1949, 1950 to 1959, 1960 to 1969, 1970 to 1979, and 1980 to 1989. Comparable rates for women were 42.7, 49.3, 42.9, 40.7, and 40.9 per 100,000 person-years. No statistically significant changes were seen in the incidence of colon and rectum cancer for men or women. There was no consistent trend in tumor stage at diagnosis and the mean size of the initial lesion did not change with time. The incidence of colorectal cancer has not changed over the past 50 years in this community where case ascertainment has been consistent and complete.

Adult↗
PubMed1995

The effect of mixtures of Lactobacillus spp. on the survival of enterotoxigenic Escherichia coli in in vitro continuous culture of porcine intestinal bacteria.

Mixtures of strains of Lactobacillus spp., two of strains inhibitory to growth of the porcine enteropathogen Escherichia coli O149: K88ac: K91 in a co-culture screen, and one of strains with no effect on this pathogen, were examined to determine their effects on the retention of this pathogen in an in-vitro continuous culture system designed to maintain a representation of the porcine ileal microflora. Strains effective in co-culture also increased the rate of decline of the pathogen in the continuous culture. The inhibitory effect exceeded the displacement effect observed with non-inhibitory strains.

Animals↗
PubMed1995

Salmonella typhimurium and Salmonella enteritidis induce gut growth and increase the polyamine content of the rat small intestine in vivo.

The effects of infection by Salmonella enteritidis and S. typhimurium on the small and large intestines, liver, spleen and mesenteric nodules of rats were studied in vivo. Both Salmonella serotypes persisted and proliferated in the gastrointestinal tract and invaded sub-epithelial tissues, mainly the ileum, leading to the systemic distribution of these pathogens. Coincidental with infection, the rate of crypt cell proliferation increased resulting in substantial growth of the small intestine. The extent of this and the accompanying accumulation of polyamines was particularly dramatic in the ileum where there was also some disruption of the villus epithelium. It is possible that these effects of the infection on the metabolism and morphology of the small bowel, which strongly resembled the changes induced by some plant lectins, may facilitate the colonisation and invasion of the gut by Salmonellae.

Animals↗
PubMed1994

Multiple hemorrhoidal bandings in a single session.

PURPOSE: The aim of our study was to evaluate the risks of multiple hemorrhoidal bandings in a single session. METHODS: We retrospectively examined all of the patients who had hemorrhoidal bandings from July 1989 to August 1992. RESULTS: Patients with multiple hemorrhoidal banding in a single session when compared with patients with single banding had greater discomfort and pain (29 percent vs. 4.5 percent), but this discomfort was usually manageable with oral analgesia of limited duration. There were also more vasovagal symptoms (5.2 percent vs. 0 percent), local swelling and edema (2.6 percent vs. 0 percent), and urinary hesitancy and frequency (12.3 percent vs. 0 percent) in the multiple-banded patients. No major complication such as massive delayed bleeding and perineal or pelvic sepsis was noted. CONCLUSION: Most patients tolerated multiple hemorrhoidal banding in a single session with acceptably low complications. Multiple banding in a single session is a safe and cost-effective alternative.

Adult↗
PubMed1994

Inhibition of enterotoxigenic Escherichia coli by the microflora of the porcine ileum, in an in vitro semicontinuous culture system.

An. in vitro fermentation system capable of maintaining at least part of the microbial population of the contents of the porcine ileum has been developed. The system was tested over the pH range 6.0-8.5, anaerobically and at dissolved oxygen concentrations within the ranges detected in the ileum of piglets at weaning (50 and 100 mumol l-1). The results demonstrated that changes in pH and dissolved oxygen within these ranges had relatively little effect on the total numbers of aerobic and anaerobic bacteria. Lactic acid bacteria, enumerated anaerobically, showed changes in viable counts in response to pH changes but were apparently unaffected by changes in dissolved oxygen, although the proportion of aerotolerant species within this group was increased at high concentrations of dissolved oxygen. The relative proportions of lactobacilli and coliforms were similar to those reported in vivo when dissolved oxygen was present at a concentration of 50 mumol l-1. Under these conditions the simulated population was consistently found to resist colonization by an enterotoxigenic Escherichia coli, of a serotype known to cause weaning scours in the piglet.

Animals↗
PubMed1994

The effect of Lactobacillus spp. on the attachment of enterotoxigenic Escherichia coli to isolated porcine enterocytes.

A total of 43 strains of lactobacilli were isolated from the gastrointestinal tract of piglets at the time of weaning. Isolates, grown on solid media, were allocated to strongly adherent or non/weakly adherent groups on the basis of numbers attaching to isolated porcine enterocytes. Strains of Lactobacillus fermentum were disproportionally represented amongst the strongly-adherent strains and Lact. acidophilus and Lact. salivarius amongst the non/weakly-adherent group. Lactobacilli showed significantly better attachment ability when grown on agar than when grown in broth culture. Strongly adherent strains were not found to effect the attachment of enterotoxigenic Escherichia coli to porcine enterocytes, tested under the conditions of exclusion (lactobacilli added to the enterocytes before E. coli), competition (lactobacilli and E. coli added simultaneously) and displacement (E. coli added before lactobacilli). Tests were made with [14C]-labelled E. coli. Suspensions of bacteria and enterocytes were passed through a filter selected to retain enterocytes but pass free bacterial cells. Counts (dpm) obtained from filters after solubilization were taken as a measure of E. coli attachment. Some strains of lactobacilli coaggregated with enterotoxigenic E. coli with K88 fimbriae, but not with a K88-negative mutants strain. These were excluded from the competitive exclusion experiments. In the apparent absence of a direct effect on the association of E. coli with host tissue, removal of potential gut pathogens by aggregation could contribute to the probiotic properties ascribed to lactic acid bacteria.

Animals↗
PubMed1993

Kidney bean lectin-induced Escherichia coli overgrowth in the small intestine is blocked by GNA, a mannose-specific lectin.

The reversible and dose-dependent hyperplastic growth of the small intestine and accelerated epithelial cell turnover caused by feeding rats with diets containing kidney bean lectin (PHA) increased the proportion of immature cells on the villi whose membrane and/or cytoplasm contained mainly simple, polymannosylated glycans. These new alpha-linked mannosyl terminals, particularly of the damaged epithelium, facilitated the preferential adherence of opportunistic Escherichia coli with mannose-sensitive Type 1 fimbriae, and other coliforms, to the glycocalyx. Accordingly, the growth of the gut was accompanied by a reversible and PHA dose-dependent overgrowth with E. coli. As expected from their common carbohydrate specificity, the inclusion in the diet of the mannose-specific agglutinin from snowdrop (Galanthus nivalis) bulbs (GNA) significantly reduced the extent of E. coli overgrowth, but abolished neither the growth nor the damage caused by PHA to the small intestine. Thus, GNA and perhaps other mannose-specific lectins, especially when used in a preventive mode, can be used to specifically block the proliferation of Type 1 E. coli in the small intestine.

Animals↗
PubMed1989

Leiomyosarcoma of the rectum and anus. A series of 22 cases.

Twenty-two patients with leiomyosarcoma of the rectum (n = 19) or the anus (n = 3) were treated surgically at the Mayo Clinic from 1950 through 1985. The majority of tumors occurred in men (1.4:1.0) during the sixth and seventh decades of life. Fifty-nine percent of the patients had symptoms including, most commonly, change in bowel habit, bleeding, and pain. Wide local excision was performed in 10 patients, whereas a more radical surgical procedure, including abdominoperineal resection (n = 8), pelvic exenteration (n = 2), and low anterior resection (n = 1), were performed in 11 patients. One tumor was unresectable. The overall survival until death from disease was 90% at 1 year, 74% at 5 years, and 51% at 10 years postoperatively. The percentage of patients free of disease at 1, 5, and 10 years postoperatively was 85, 62, and 40, respectively. Wide local resection was not superior to a more radical surgical approach in preventing tumor recurrence or improving survival. Lesions less than 2.5 cm and confined to the bowel wall can be treated by wide local excision, whereas larger or more extensive tumors should be treated by a more radical surgical approach.

Actuarial Analysis↗
PubMed1987

Sphincter repair for fecal incontinence after obstetrical or iatrogenic injury.

Forty patients with fecal incontinence underwent sphincter repair between 1975 and 1984. Divided sphincter musculature resulted from obstetrical injury in 23 and previous anorectal surgery in 17. Eighteen had undergone a previous attempt at repair. Fifteen patients experienced seepage of stool and 25 had gross incontinence. In nine patients, reconstruction of the external sphincter was by overlap of the muscle ends. Twenty-four others underwent accurate approximation of the external sphincter muscle and anterior plication of the levator muscles, and in seven the anal canal was made smaller by narrowing the anal orifice. Follow-up was an average of 67 months after operation (range, 2.4 to 166 months). Continence was objectively improved in 62 percent (P less than .01) when performance criteria were analyzed by Wilcoxon signed-rank test, although 85 percent of the patients reported subjective improvement. Requirements for protective pads were reduced in 57 percent (P less than .01) and fewer social limitations were experienced in 52 percent (P less than .01). There was no significant correlation between outcome and type of operation.

Adult↗
PubMed1986

Preoperative staging of rectal carcinoma by computed tomography and 0.15T magnetic resonance imaging. Preliminary report.

A prospective study was done on 34 patients using magnetic resonance imaging (MRI) and computed tomography (CT) preoperatively to stage patients with known rectal carcinoma. The study was done to determine the accuracy and clinical usefulness of CT and MRI. The Thoeni staging method was used. Twenty-four of 30 cases were staged correctly by CT. Sixteen of 27 were staged correctly by MRI. CT detected lymph node metastases in six of 15 cases with one false-positive. MRI detected lymph node metastases in two of 15 patients with one false-positive. CT was the preferred examination, and was useful in some cases. These cases included patients with small tumors who were considered for local excision and patients with extensive disease who were candidates for preoperative or intraoperative radiation treatment. MRI demonstrated extensive disease, as did CT in our later cases.

Adult↗
PubMed1986

Colorectal polyps and the risk of subsequent carcinoma.

Of 323 patients with colorectal polyps that either were larger than 1 cm in diameter or were 1 cm or smaller but had been subjected to biopsy or excision, 20 (6%) had subsequent development of a colorectal carcinoma, an incidence rate of 4.6 per 1,000 person-years of follow-up. These 20 cases of cancer compared with 7.38 cases expected; thus, the risk of colorectal carcinoma in these patients was 2.7 times that in the general population (P less than 0.001). Although risks were greater for certain subgroups of patients, the differences detected were usually modest. We conclude that patients with large colorectal polyps (more than 1 cm in diameter) should be closely followed up after treatment of the initial polyp, regardless of the size, site, or histologic type of the polyp, the age or sex of the patient, or the type of initial treatment (excision or fulguration). Those patients with more than one polyp, especially if more than one segment of the colon is involved, need special attention. Examination of the entire colon is important because the site of development of carcinoma may be distant from the site of the initial polyp.

Actuarial Analysis↗
PubMed1986

An appraisal of endoscopic removal of malignant colonic polyps.

The issue of whether patients who have invasive carcinoma in an otherwise benign polyp should undergo surgical resection of that bowel segment is controversial. We examined the records of 83 patients with such polyps that were removed endoscopically between 1978 and 1981. After exclusion of 18 patients from the study for various reasons, our study group consisted of 65 patients who had undergone complete endoscopic removal of 69 polyps that contained a malignant process. Carcinoma in situ was found in 34 polyps, and 3 patients with such polyps had a recurrent malignant lesion of the same degree. These recurrent tumors were treated successfully by aggressive endoscopic removal. Seventeen polyps that contained invasive carcinoma were treated endoscopically without resection, and two patients in this group subsequently had recurrent carcinoma at the site of the original polyp. These recurrent lesions were resected, and neither patient had evidence of nodal metastasis. Of the 18 patients who underwent immediate resection of invasive carcinoma, 2 had residual carcinoma at the time of the resection, although no lymph node metastasis was found. We conclude that colonic polyps with carcinoma in situ can be treated safely with complete endoscopic removal. Invasive carcinoma in a polyp can be treated safely with complete polypectomy, and immediate resection may not be necessary. This group of patients, however, should undergo thorough follow-up studies and periodic endoscopic reexamination.

Adenocarcinoma↗
PubMed1985

Retrorectal tumors. Mayo Clinic experience, 1960-1979.

One hundred twenty patients with primary retrorectal tumors (79 congenital, 14 neurogenic, 13 osseous, and 14 miscellaneous) had their initial treatment at the Mayo Clinic from 1960 to 1979. The mean age was 43 years (100 patients were adults). Female predominance was associated with congenital cysts (15:1) and male predominance with chordomas (5:1). Forty-three percent of the patients had malignant lesions. No dermoid cysts were found in this series. Diagnosis was made by digital examination or sacral radiographs in all patients. Computed tomography scan was the most important diagnostic method; the rate of positive findings was 100 percent in 20 patients. Approach to the tumor was posterior in 79 of 102 patients in whom resection was possible. Ten of 66 patients with benign tumors had recurrence. The five-year survival rate for patients with chordomas was 75 percent and for patients with other malignant lesions was 17 percent. Because preoperative biopsy can cause tumor spread, abscess, fecal fistula, or meningitis, it should not be performed if tumors are potentially resectable. Whenever possible, total resection should be done.

Adolescent↗
PubMed1984

Carcinoma of the anal canal. A clinical and pathologic study of 188 cases.

Among 188 patients presenting with carcinoma of the anal canal the predominant cell types were squamous cell (56%) and nonkeratinizing basaloid (35%). Thirteen patients who had predominantly small (less than or equal to 2 cm) and only superficially invasive squamous cell lesions were treated with local excision, and although one required later abdominal perineal (AP) resection for local recurrence, all were apparently cured. Local excision should be preferred as initial treatment for such lesions. One hundred eighteen patients with squamous cell and nonkeratinizing basaloid carcinomas were primarily treated with AP resection. The operative mortality rate was 2.5%. Among 114 patients who survived surgery and had adequate follow-up, 40% developed recurrent disease, and 71% have survived 5 or more years. Pathologic staging based on depth of tumor invasion and regional nodal involvement was strongly predictive of survival as was tumor histology with progressively poorer survival rates from low-grade squamous cell to high-grade squamous cell to nonkeratinizing basaloid types. Tumor size was inversely related to prognosis and was strongly associated with stage. Squamous cell anal carcinoma was dominantly a local disease with approximately 70% of patients presenting with tumor apparently limited to the bowel wall, only 20% with regional node involvement and only 2% with distant metastasis. Even among those patients who recurred after AP resection approximately 80% had all known disease still limited to the pelvic area. Corresponding figures for nonkeratinizing basaloid tumors were 50 percent presenting limited to the bowel wall, 30% with regional nodes, 20% with distant metastasis, and 60% with initial recurrence limited to the pelvis. Among the 13 patients studied with small cell anal carcinoma, the authors found the disease to be very virulent either initially presenting with or rapidly evolving into diffuse dissemination. Only one of the seven patients who could be treated surgically survived 5 years. As is true for small cell carcinomas primary to other sites, this neoplasm should be regarded as a systemic disease. With these findings as a foundation, possible future strategies for management of anal carcinoma are discussed.

Adult↗
PubMed1984

Fissurectomy with superficial midline sphincterotomy. A viable alternative for the surgical correction of chronic fissure/ulcer-in-ano.

A series of 121 patients with chronic fissure-in-ano who underwent fissurectomy with superficial midline sphincterotomy was studied. The mean follow-up was 8.1 years. Minor problems with anal competence occurred after the operation in 30 patients (25 per cent). Within two months, this problem had resolved in all patients. One patient (0.8 per cent) had a true recurrence. Five patients (4.1 per cent) had recurrent acute anal abrasions as the result of passage of a hard stool. These healed spontaneously. Twelve patients (9.9 per cent) had fragile scars, but this was a significant problem in only five (4.1 per cent). No patient had significant stricture formation, keyhole deformities, or major persistent problems with anal competence. The patients graded their operations with regard to satisfaction: 118 (97.5 per cent) reported satisfactory results and three (2.5 per cent) reported unsatisfactory results. This study shows that fissurectomy with superficial midline sphincterotomy is a viable approach to the surgical management of chronic fissure-in-ano.

Anal Canal↗
PubMed1984

Manometric studies in rectal prolapse.

Manometric studies of internal sphincter responses were carried out on 15 patients--14 with rectal prolapse and one with mucosal prolapse with proctitis cystica profunda. In all 12 patients studied preoperatively, the internal sphincter reflexes (inhibitory reflex) were absent or markedly obtunded. Anterior resection was performed on three of the patients in whom preoperative and postoperative manometric studies could be carried out. In one, the inhibitory reflex returned to normal after successful corrective surgery and in one, absence of the reflex persisted after anterior resection and this patient eventually had recurrent rectal prolapse.

Aged↗