Biomedical subjects
P H Gordon
Publications and source records attributed to P H Gordon.
Effect of 5-fluorouracil and leucovorin on the integrity of colonic anastomoses in the rat.
PURPOSE: This study was designed to determine the effects of 5-fluorouracil and leucovorin on the healing of colonic anastomoses and assess the safety of conducting a colonic resection and anastomosis during and shortly after a course of this chemotherapy in a rat model. METHODS: Fifty-six male Wistar rats, weighing 200 to 250 gm, were divided into four groups, each consisting of 14 animals. Animals in Group I (control group) underwent colon resection and primary anastomosis. Animals in Group II received 10 mg/kg intravenous 5-fluorouracil and 10 mg/kg leucovorin once a week for four weeks and then underwent the same operation. Animals in Groups III and IV received the same drug dosage for six weeks and were operated at different intervals: Group III at one week and Group IV at two weeks after completion of chemotherapy. Within each group, one-half of the animals were sacrificed on the third postoperative day and one-half on the seventh postoperative day, and anastomotic bursting pressure measurements were performed. RESULTS: At three and seven days, mean bursting pressure of the anastomoses were determined: 98 mmHg and 180.7 mmHg in Group I, 95 and 197.8 in Group II, 85.7 and 189.2 in Group III, and 98.6 and 179.2 in Group IV, respectively. There was no significant difference in bursting pressure between treated animals and controls by the third postoperative day or by the seventh day. The burst occurred at the anastomosis in all specimens tested on the third postoperative day and in the bowel wall adjacent to the anastomosis in all specimens tested on the seventh postoperative day. CONCLUSION: This study demonstrates that the above regimen of chemotherapy has no effect on the healing of colonic anastomoses and that surgery can be performed safely during and shortly after this regimen of chemotherapy.
Proliferative activity at rectal anastomoses performed with various suture materials. An experimental study.
BACKGROUND: Suture line recurrence continues to be an important cause of failure following curative resection for colorectal carcinoma. Our aim was to determine whether the nature of the suture material used affected the proliferative activity of colonic crypt cells at the anastomosis. METHODS AND MATERIALS: Sprague-Dawley rats were randomized into one control and three experimental groups. In each experimental group the proximal 2 cm of rectum were resected and anastomoses constructed with titanium clips, interrupted 6-0 Vicryl (Ethicon, Inc., Somerville, NJ), and interrupted 6-0 silk. Control animals had a sham operation. One-quarter of each group of rats were killed at 14, 30, 60, and 90 days. Each animal received intraperitoneal tritiated thymidine 30 minutes before death. Each anastomosis was harvested, and longitudinally oriented crypts were analyzed for the total number and position of labeled cells at five equal distances from the anastomosis. Random crypts were studied in the control group. RESULTS: Labeling indices were increased in almost all experimental groups at days 14, 30, 60, and 90. There were no persistent, statistically significant differences in labeling indices among the various suture materials. CONCLUSION: The type of suture material used did not significantly affect the proliferative rate in this animal model.
Expression of proliferation-specific genes in the mucosa adjacent to colon carcinoma.
BACKGROUND: One of the main concerns in colon carcinoma therapy is local recurrence of the malignancy at the site of resection. Previous studies have shown that morphologically normal-appearing mucosa adjacent to colon carcinoma is different from mucosa distant from carcinoma. Mucosa adjacent to a carcinoma is characterized by crypt lengthening, cell hypertrophy, and change in production of mucopolysaccharides from sulfomucin in normal mucosa to sialomucins in carcinomas and adjacent mucosa. Recently there have been reports suggesting that there is an upward extension of the proliferative compartment in colonic crypts of this adjacent mucosa. METHODS: Immunoblot analysis using antibodies to retinoblastoma, statin, c-Fos, c-Jun, and Cdc-2 proteins was used for our study on the expression of early cell cycle genes in carcinoma and its adjacent mucosa. In all, 15 tissue samples obtained from patients with colon carcinoma were analyzed. Tissue specimens were collected and immediately dissected as tumor, 0 to 1, 1 to 2, 2 to 3, 3 to 4, and 4 to 5 cm from the primary lesion. Dissected pieces were homogenized separately and subjected to immunoblot analysis. RESULTS: We found upregulation of c-Fos, c-Jun, and Cdc-2 expression in carcinoma and adjacent mucosa up to 4 cm from the edge of the carcinoma. The phosphorylated form of retinoblastoma is present in the carcinoma as well as in adjacent mucosa up to 4 cm from the margin of the carcinoma. Furthermore, we observed that the level of statin, a nonproliferation-specific nuclear protein, is very low in the primary lesion and in adjacent mucosa up to 3 cm. CONCLUSIONS: These results indicate that adjacent tissue up to 3 to 4 cm from the carcinoma has elevated levels of expression for cell cycle traverse-associated genes and down-regulation of nonproliferation-specific gene expressions such as statin. This imbalance indicates that within 3 to 4 cm from the edge of the carcinoma, colonic epithelial cells are already abnormal and may be in the hyperproliferative and preneoplastic state, susceptible to further steps leading to eventual malignant transformation.
An investigation into the fluoride release of a variety of orthodontic bonding agents.
The purpose of this study was to compare the fluoride release from a variety of orthodontic bonding agents. Fluoride release into de-ionized water was measured over a 20-week period. Material based on the fluoride exchange resin was also tested in a saline solution. Fluoride release from a variety of orthodontic bonding agents was compared and the amount of release found to be highly variable. Glass ionomer-based materials showed substantially greater fluoride release when compared with resin-based materials. The presence of anions (Cl-) did not improve the release from fluoride exchange resin. Glass ionomer/resin hybrid material (Vitrabond) released the greatest amount of fluoride.
The effect of artificial saliva on the frictional forces between orthodontic brackets and archwires.
The effect of artificial saliva on the static and kinetic frictional forces of stainless steel (Dentaurum) and polycrystalline ceramic (Transcend) brackets in combination with 0.018-inch round and 0.019 x 0.025-inch Edgewise archwire sizes and stainless steel, nickel-titanium and beta-titanium archwire materials, under a constant ligature force were investigated. In all cases, artificial saliva had the effect of increasing the frictional force when compared with the dry state.
An investigation to estimate the fluoride uptake adjacent to a fluoride-releasing bonding agent.
Decalcification of the teeth remains a problem during orthodontic treatment with fixed appliances. It has been suggested that bonding agents which release fluoride could supply it to the area of the tooth most at risk from decalcification. The aim of this study was to estimate uptake by enamel adjacent to a fluoride releasing bonding agent. Acid etch biopsies were used to estimate the concentration of fluoride in enamel adjacent to brackets bonded with Vitrabond and Geristore. Results indicate that there was a significant increase in the concentration of fluoride in enamel adjacent to Vitrabond. The clinical significance of the increase in the concentration of fluoride adjacent to Vitrabond and the mechanism by which fluoride moves from the material into the enamel remain unclear.
The effect of sandblasting on the retention of first molar orthodontic bands cemented with glass ionomer cement.
This study examined the effect of sandblasting, in vitro, on the bond strength and survival time of first molar orthodontic bands. Survival time was assessed following simulated mechanical fatigue in a ball mill. The amount of cement left attached to the band after debanding was also assessed. In addition, the effect of sandblasting on the failure rate of 320 first molar bands cemented in 107 patients was examined in a half-mouth trial. Ketac-cem, mixed according to manufacturers' instructions was used as the luting agent for both laboratory and clinical trials. In vitro, sandblasting increased bond strength by 27 per cent (P < 0.01) and produced a three-fold increase in the median survival time relative to the untreated sample (P < 0.001) in the ball mill experiment. Sandblasting resulted in more cement remaining on the band rather than on the tooth enamel after band removal. In vivo, sandblasting reduced the clinical failure rate of the first molar bands (P < 0.001).
Hepatic resection for colorectal liver metastases.
The lack of other effective treatment for colorectal liver metastases makes hepatic resection a primary treatment consideration. Between January 1980 and December 1990, 26 selected patients with liver colorectal metastases who underwent hepatic resection were reviewed. The age, sex, site of primary lesion, histological grade, lymph node involvement, location, size, and number of hepatic metastases, type of hepatic resection, and preoperative CEA blood levels were documented. Complete removal with histologically negative resection margins were accomplished in 24 patients. The extent of resection performed was hepatic lobectomy in 12 patients. Segmentectomy in eight patients, and wedge resection in four patients. The 5-year survival rate was 30.5 per cent. Patients with metachronous metastases showed a better survival rate than those with synchronous lesions--46.6% versus 13.6% respectively (P = 0.08). None of the other factors studied showed a significant effect on survival. All patients were followed from the time of hepatic resection to the time of this study or death. During a median follow-up of 30.9 months, 20 patients developed recurrence of their disease (60 per cent in the liver). There was no perioperative mortality. Morbidity arose in 66.6 per cent of patients, with a majority of the complications being minor. We conclude that hepatic resection can be performed safely enough to be recommended in selected patients.
Selected operative management of fistula-in-ano in Crohn's disease.
PURPOSE: The operative management of patients with fistula-in-ano in the presence of Crohn's disease has been controversial. Our aim was to review the results of operative treatment in this clinical setting. METHODS: Twenty-eight such patients treated between 1976 and 1990 were reviewed. The duration of local symptoms, location of the Crohn's disease, medications, and previous operations were noted. An effort was made to classify the fistula-in-ano according to Parks' classification, but many fistulas were complicated and did not neatly fit into one of the described categories (intersphincteric 9, transsphincteric 10, complex 9). Patients underwent fistulotomy (three with a seton). RESULTS: Complete healing was achieved in 71.4 percent of cases with an average healing time of 3.5 months (range, 3 weeks-26 months). With an average follow-up of 71 months (range, 12 months-14 years), postoperative function was good in 20 (71.5 percent) patients. Of the remaining eight patients, five ultimately underwent total proctocolectomy because of the severity of their colorectal disease, one patient developed alteration of continence, and two patients developed stenosis. There were two recurrences, (one at nine months and one at six years). CONCLUSION: Operative treatment should be offered to selected patients with fistula-in-ano in the presence of Crohn's disease.
Proliferative activity at colonic anastomoses as determined by statin. A nonproliferation-specific nuclear protein.
PURPOSE: One theory of anastomotic recurrence in large bowel carcinoma is that epithelial hyperplasia at the suture line causes metachronous carcinoma. METHODS: S44, a monoclonal antibody directed against statin, a nuclear protein expressed in quiescent cells, was used to determine whether the anastomosis represents an area with a high proliferation rate. During follow-up colonoscopic examination of patients who had undergone previous resection for colorectal carcinoma, biopsies were taken from the anastomotic site and from the mucosa 10 to 15 cm from the anastomosis. One side of 10 well-oriented crypts was counted for each patient with the number of nuclei positive for statin being determined by the presence of dark brown reaction product. RESULTS: The average percentages of statin-positive cells varied between 19.4 and 44.4 (average, 31.3 +/- 6.5) for the normal mucosa and 22.8 to 35.1 (average, 29.98 +/- 3.67) for the anastomotic mucosa. The differences were not significant. There were no differences between those patients in whom the postoperative time elapsed was two years or less and those greater than two years. CONCLUSION: This study is unique in that the proliferative activity at the site of colonic anastomosis was determined in a clinical setting, and patients in which the anastomoses were created anywhere from 1 to 14 years earlier were included. Using S44 as a marker, this study does not support the theory that suture line recurrence is a result of an enhanced proliferation rate.
A 5-year clinical review of bond failure with a no-mix adhesive (Right on).
The performance of 5941 stainless steel orthodontic brackets bonded with a no-mix adhesive (Right-on) in 563 patients was reviewed over a 5-year period. The effects of age and sex of the patient, treatment mechanics, operator experience, and arch location on the failure rate and mean survival time (MST) of bonded orthodontic brackets were examined. The overall failure rate was 8 per cent (MST 45.7 months). The failure rate of brackets was three times greater in patients aged less than 12 years at the start of treatment compared with those aged greater than 16 years at the start of treatment. The MST was significantly different between male and female patients. Brackets bonded in patients treated with Begg mechanics had a greater failure rate than those bonded in patients treated with other appliance mechanics. The failure rates and MST of brackets were significantly affected by all the variables examined.
A laboratory investigation into cements used to retain orthodontic bands.
A laboratory study is presented where a technique of band retention testing is characterized. A glass polyalkenoate and a zinc phosphate cement were evaluated for band retention under simulated conditions of mechanical stress. In the absence of mechanical and other stresses there was no difference in the two cements for band retention. However, after mechanical stress was applied the glass polyalkenoate cement proved superior to the zinc polyalkenoate cement for band retention (P < 0.05). Weibull analysis is presented and described as a useful adjunct to statistical handling of band retention data.
The shortened dental arch: supplementary analyses from the 1988 adult dental health survey.
Information on 2297 dentate adults, aged 15-75+ years, who participated in the 1988 national survey of adult dental health in the United Kingdom, was reviewed in order to determine what proportion in each age group fulfilled the criteria for a 'shortened dental arch'. The proportion of people with four good quadrants was 90 per cent at 16-24 years falling to 2 per cent at 65-74 years. Overall, 54 per cent of the sample had four good quadrants. This is a more stringent measure of dental health than the proportion with 21 or more standing teeth, where the corresponding values were 100 per cent, 24 per cent and 80 per cent.
A look through the "retrospectoscope": reflections and realities on a decade of evolution of colorectal surgery in Canada. Colorectal guest lecture.
Although the origin of colorectal surgery dates back to 1835, it has only been in the past decade that major strides in this specialty have been made in Canada. The Canadian Society of Colon and Rectal Surgeons was incorporated in 1983. Many other countries have also established national societies of colon and rectal surgery. In Canada, acknowledgement of the importance of the specialty has been slow for a number of reasons, not least of which have been concerns over turf. Nevertheless, it is unrealistic to expect a surgeon whose operative experience is spread thinly over numerous segments of surgery to equal the current achievement of various experts in only one of these fields. Despite their small numbers, members of the Canadian Society of Colon and Rectal Surgeons have made disproportionately large contributions to clinical care, teaching and research. A vibrant image and vital subjects of study will positively sustain the future direction of the specialty.
The prophylactic use of ureteral catheters during colorectal operations.
The necessity for preoperative ureteral catheter insertion for colorectal operations continues to be controversial. To determine our experience and what complications might be associated with ureteral catheter use, the charts of all patients in our department undergoing ureteral catheterization in combination with colorectal procedures between the years 1978 and 1989 were reviewed. The indications for operation, the presence or absence of urinary tract symptoms, and intravenous pyelogram findings (if performed) were recorded. Time for the procedure, size and number of catheters, and complications were noted. From the operative report, a retrospective grading of necessity for ureteral catheterization was assessed according to a scale from A to D. There were 120 ureteral catheterizations performed, bilaterally in 60 per cent of cases. Complications included renal colic (1), oliguria (1), and anuria (2). Intraoperatively, one ureter was cut and one ureter tied but recognized by palpation and ligature removed. Retrospective grading deemed ureteral catheterization necessary in 27.5 per cent of cases. We conclude that catheters are helpful in selected cases. For patients with bilateral catheter insertion, complications can be reduced by ensuring urine output prior to removal of the second catheter.
Perioperative blood transfusion and outcome after resection for colorectal carcinoma.
The degree of immunomodulation by perioperative blood transfusion and its effect on oncological surgery remain controversial. A major problem with previous clinical studies has been the inadequate patient population in each and the presence of confounding variables. To resolve some of the controversy, all studies published between 1982 and 1990 were reviewed using the statistical method of Mantel-Haentszel-Peto to determine a cumulative estimate of the direction and magnitude of this association. Some 20 papers were included in the analysis, representing 5236 patients. The cumulative odds ratios (95 per cent confidence interval) of disease recurrence, death from cancer and death from any cause were 1.80 (1.30-2.51), 1.76 (1.15-2.66) and 1.63 (1.12-2.38) respectively. These results support the hypothesis that perioperative blood transfusion is associated with an increased risk of recurrence of colorectal carcinoma and death from this malignancy.
Endophytic malignant transformation within flat adenoma of the colon: a potential diagnostic pitfall.
A 74-year-old man was found to have a 1 cm, slightly elevated and flat, red mucosal lesion of the descending colon. An endoscopic biopsy showed a structure characteristic of a tubular adenoma. The surgical specimen revealed an inverted, transmural, solid and cystic lesion. The superficial (intra-mucosal) component of the neoplasm was histologically characteristic of a flat adenoma, showing epithelial dysplasia. However, the contiguous deep component was a well-differentiated adenocarcinoma extending to the serosa and demonstrating the unusual features of a circumscribed lobulated topography and the absence of an inflammatory/desmoplastic stromal reaction. Endophytic malignant transformation within a flat adenoma should be distinguished from conditions of misplaced glandular epithelium such as localized colitis cystica profunda. Complete and full mucosal thickness endoscopic snare removal is indicated in order to assess the degree of epithelial dysplasia and detect endophytic malignant transformation.