Search PubMed⌕ Search

Biomedical subjects

R W Beart

Publications and source records attributed to R W Beart.

At least 19 recordsLinked to original sources
PubMed1997

The learning curve for laparoscopic colorectal surgery. Preliminary results from a prospective analysis of 1194 laparoscopic-assisted colectomies.

BACKGROUND: Laparoscopic-assisted colectomy is an emerging technology for patients with cancer, polyps, inflammation, and other types of pathologic conditions. While previous studies have shown better outcomes for laparoscopic cholecystectomies when surgeons perform more procedures, there is no information on the relationship between surgeon volume and outcomes for laparoscopic-assisted colectomy. OBJECTIVE: To evaluate whether better clinical outcomes are found for surgeons who perform higher numbers of laparoscopic-assisted colectomies and whether such a relationship, if it exists, applies to both intraoperative and postoperative outcomes. DESIGN: Analysis of a data set of 1194 patients, operated on by 114 surgeons, from a prospective registry sponsored by the American Society of Colon and Rectal Surgeons, from May 1991 to October 1994. MAIN OUTCOME MEASURES: Completion rate, intraoperative and postoperative complications, and length of hospital stay. RESULTS: In 75% of cases, surgery was completed laparoscopically, with no difference between high-volume surgeons (> or = 40 cases) and low-volume surgeons. Length of stay (average, 6 days) did not vary according to surgeon volume. Postoperative complications occurred in 15% of cases, with a significantly lower rate for high-volume surgeons (10% vs 19%; P < .001). Intraoperative complications occurred in 5% of cases, with a nonsignificant trend toward a lower rate for high-volume surgeons (3.7% vs 6.3%). A multivariate regression analysis, adjusting for type of disease (cancer vs inflammation vs polyps) and for level of difficulty of the procedure (high vs low) showed that for high-volume surgeons there is a lower probability of both intraoperative complications (adjusted odds ratio, 0.56; 95% confidence interval, 0.32-0.97; P = .04) and postoperative complications (adjusted odds ratio, 0.48; 95% confidence interval, 0.34-0.68; P < .001). CONCLUSIONS: There is a learning curve for laparoscopic-assisted colectomy with respect to intraoperative and postoperative outcomes. As with other laparoscopic procedures, surgeons who perform higher volumes of laparoscopic-assisted colectomy have lower rates of intraoperative and postoperative complications.

Colectomy↗
PubMed1997

Variations in treatment of rectal cancer: the influence of hospital type and caseload.

PURPOSE: Surgical options for the treatment of rectal cancer may involve sphincter-sparing procedures (SSP) or abdominoperineal resection (APR). We sought to examine variations in the surgical treatment of rectal cancer for a large, well-defined patient population and specifically to determine if differences exist in management and survival based on hospital type and surgical caseload. METHODS: The Cancer Surveillance Program database for Los Angeles County was used to retrospectively retrieve data on all patients who underwent SSP or APR for rectal adenocarcinoma between 1988 and 1992. RESULTS: A total of 2,006 patients with adenocarcinoma of the rectum underwent SSP or APR during the study period. Overall, 55 percent underwent SSP, and the remaining 45 percent underwent APR. Use of SSP remained relatively constant for each year of the five-year period. Substantial variability was seen in the use of SSP at various hospital types. For localized disease, this varied from as low as 52 percent at teaching hospitals to as high as 78 percent at hospitals approved by the American College of Surgeons (P = 0.067). To examine the role of caseload experience, hospitals were divided into those completing an average of five or fewer rectal cancer cases per year vs. those completing an average of more than five cases per year. For localized disease, hospitals with higher caseloads performed SSP in significantly more cases, 69 vs. 63 percent (P = 0.049). Survival was seen to be significantly improved for patients operated on at hospitals with higher caseloads, in cases of both localized and regional diseases (P < 0.001). CONCLUSION: Surgical choices in the treatment of rectal cancer may vary widely, even in a well-defined geographic region. Although the reasons for this variability are multifactorial, hospital environment and surgical caseload experience seem to have a significant role in the choice of surgical procedure and on survival.

Adenocarcinoma↗
PubMed1997

Oral Fleet Phospho-Soda laxative-induced hyperphosphatemia and hypocalcemic tetany in an adult: report of a case.

PURPOSE: This study was undertaken to report an adverse outcome of the routine use of Fleets Phospho-Soda for bowel cleansing and to review the available literature. METHOD: Report of a case and review of the literature is presented. RESULT: Administration of Fleets Phospho-Soda for bowel preparation in an adult resulted in hyperphosphatemia and hypocalcemic tetany. Review of the literature shows this to be the first such report. Further evaluation suggests a role for partial bowel obstruction and renal failure in this complication. CONCLUSION: Although Fleet Phospho-Soda solution continues to be a safe bowel preparation, caution should be used in adults with bowel obstruction and renal failure.

Acute Kidney Injury↗
PubMed1997

Laparoscopic colectomy.

Laparoscopic treatments for benign colonic disease and as palliative operations for advanced malignant disease have gained widespread acceptance as safe, efficacious, and beneficial treatment options. There are also strong indications that laparoscopic treatment for malignant colorectal disease is a viable alternative in selective patients. Further studies with substantial follow-up to determine the adequacy of resection and the comparability of cure rates are needed to assess any changes in the long-term staging and survival patterns of these treatments.

Colectomy↗
PubMed1996

Mechanisms for the involvement of DNA methylation in colon carcinogenesis.

C --> T transitions at CpG sites are the most prevalent mutations found in the p53 tumor suppressor gene in human colon tumors and in the germline (Li-Fraumeni syndrome). All of the mutational hot spots are methylated to 5-methylcytosine, and it has been hypothesized that the majority of these mutations are caused by spontaneous hydrolytic deamination of this base to thymine. We have previously reported that bacterial methyltransferases induce transition mutations at CpG sites by increasing the deamination rate of C --> U when the concentration of the methyl group donor S-adenosylmethionine (AdoMet) drops below its Km, suggesting an alternative mechanism to create these mutations. Unrepaired uracil pairs with adenine during replication, completing the C --> T transition mutation. To determine whether this mechanism could contribute to the development of human colon cancer, we examined the level of DNA (cytosine-5)-methyltransferase (MTase) expression, the concentration of AdoMet, and the activity of uracil-DNA glycosylase in human colon tissues, and searched for the presence of mutations in the MTase gene. Using reverse transcription-PCR methods, we found that average MTase mRNA expression levels were only 3.7-fold elevated in tumor tissues compared with surrounding normal mucosa from the same patient. Also, no mutations were found in conserved regions of the gene in 10 tumors sequenced. High-performance liquid chromatographic analysis of extracts from the same tissues showed that AdoMet concentrations were not reduced below the Km value for the mammalian enzyme, and the concentration ratio of AdoMet:S-adenosylhomocysteine, the breakdown product of AdoMet and the competitive MTase inhibitor, did not differ significantly. Finally, extracts from the tumor tissue efficiently removed uracil from DNA. Therefore, biochemical conditions favoring a mutagenic pathway of C --> U --> T were not found in a target tissue known to undergo a high rate of C --> T transitions at CpG sites.

Base Sequence↗
PubMed1996

Intraabdominal abscesses following laparoscopic and open appendectomies.

BACKGROUND: The purpose of this review was to evaluate the incidence of postoperative intraabdominal abscess formation following laparoscopic and open appendectomies. METHODS: The current study retrospectively examines appendectomies performed during the period from January 1993 to July 1994. Excluded were cases which were started laparoscopically but converted to open procedures. There were 1,287 cases identified; 597 were perforated (46%), 114 were gangrenous (9%), and 576 were acute (45%). These diagnoses represent intraoperative diagnoses. RESULTS: Of the 576 appendectomies for acute appendicitis, 64 (11%) were performed laparoscopically. There were four intraabdominal abscesses (0.7%), all occurring after open procedures. Of the 114 appendectomies for gangrenous appendicitis, 16 (14%) were done laparoscopically. There were two postoperative abscesses (1.8%), one following an open and one following a laparoscopic procedure. There was no significant difference in abscess rate between laparoscopic and open appendectomies for either acute or gangrenous appendicitis. Of the 597 appendectomies for perforated appendicitis, 28 (5%) were done laparoscopically. There were 19 postoperative abscesses in the whole group, accounting for a 3.2% abscess rate. Sixteen abscesses occurred after open appendectomies and three occurred after laparoscopic appendectomies (2.9% vs 11%, P = 0.054). The preoperative diagnosis was incorrectly identified as acute appendicitis in 95 cases subsequently found to have perforated appendicitis; there was only 1 postoperative abscess in this group. There was no difference in postoperative stay in the open vs laparoscopic group (6.3 days vs 6.1 days). CONCLUSIONS: We found no significant difference in the rate of postoperative intraabdominal abscess formation between laparoscopic and open appendectomies in cases of acute or gangrenous appendicitis. However, laparoscopic appendectomy for perforated appendicitis was associated with an important trend toward a higher rate of postoperative intraabdominal abscess formation than open appendectomy. This observation calls for closer prospective scrutiny of laparoscopic appendectomy in the setting of perforated appendicitis.

Abdominal Abscess↗
PubMed1996

Inferior vena caval blood flow and cardiac hemodynamics during carbon dioxide pneumoperitoneum.

BACKGROUND: The effects of carbon dioxide pneumoperitoneum on venous return and cardiac hemodynamics during laparoscopic surgery were studied. METHODS: Twelve adult pigs underwent placement of an electromagnetic flow meter across the infrarenal vena cava (IVC) as well as placement of Swan Ganz and arterial monitoring catheters. Measurements of the flow through infrarenal IVC, cardiac output (CO), pulmonary capillary wedge pressure (PCWP), mean arterial pressure (MAP), and heart rate were recorded at baseline, 5 and 60 min following insufflation to 15 mmHg with CO2, and 5 min following desufflation. Stroke volumes and systemic vascular resistance (SVR) were calculated as well. RESULTS: Flow through the IVC dropped by 24 and 31% at 5 and 60 min (p = 0.03 and 0.02, respectively). Paradoxically, cardiac output rose by 14 and 28% at 5 and 60 min (p = 0.03 at 60 min). Central venous and pulmonary capillary wedge pressures rose transiently by 35 and 36% at 5 min before returning to baseline (p < 0.01). Mean arterial pressure and heart rate remained relatively constant during insufflation. Systemic vascular resistance diminished from 938 dynes/cm/s prior to insufflation to its nadir at 60 min of 650 dynes/cm/s (p < 0.01). CONCLUSIONS: These observations suggest potentially complex interactions between the mechanical and systemic effects of the CO2 pneumoperitoneum on venous return. Transient elevations in cardiac filling pressures occur by an unknown mechanism, and a generalized enhanced inotropic state mediated via increased sympathetic outflow is observed in this hypercapnic anesthetized animal model.

Animals↗
PubMed1996

Level of highest mean resting pressure segment in the anal canal. A quantitative assessment of anal sphincter function.

PURPOSE: Even with the development of new technologies, the mechanism of fecal continence is still not completely understood. This study evaluates the relative position of the highest mean resting pressure (HMRP) in the anal canal and its correlation with function in incontinent patients and in controls. METHODS: Sixteen incontinent patients (mean age, 47.1 +/- 13.9 (range, 18-63) years; 12 female) and 16 controls (mean age, 35.4 +/- 8.7 (range, 24-58) years; 12 female) were studied using a water-perfused eight-port radial catheter computer-assisted vectromanometry. Position of the HMRP was analyzed in relation to the anal verge (D1) and to the proximal functional border of the anal canal (D2). RESULTS: Controls had HMRP located more distally in the anal canal, because D2 was significantly higher than D1 (mean, 3.45 +/- 0.75 vs. 1.81 +/- 0.63 cm; p + 0.001). For incontinent patients, D1 and D2 were similar (mean, 1.86 +/- 0.75 vs. 2.08 +/- 1.11 cm; not significant). Comparison of the relative position of the HMRP between patients and controls showed a more proximal location for incontinent patients than controls (mean, 49.1 +/- 12.1 percent vs. 35.4 +/- 10.2 percent; p = 0.002). CONCLUSIONS: Position of the HMRP is significantly more proximal for incontinent patients than for controls, and measurement of the distance from the anal verge to the HMRP in relation to the full length of the anal canal may represent another way to quantitatively assess anal sphincter function.

Adolescent↗
PubMed1996

Wound recurrence following laparoscopic colon cancer resection. Results of the American Society of Colon and Rectal Surgeons Laparoscopic Registry.

INTRODUCTION: Multiple case reports have suggested that laparoscopic resection of colon cancer may alter the pattern or incidence of cancer recurrence. All reports lack a significant denominator to evaluate the incidence of surgical wound recurrence. We hypothesized that wound recurrence incidence is not increased by laparoscopic resection of colon cancer. METHODS: A prospective registry was initiated under the auspices of The American Society of colon and Rectal Surgeons, American College of Surgeons, and Society of American Gastrointestinal Endoscopic Surgeons in 1992. Patients having laparoscopic colon resection were voluntarily entered and followed until June 1995. Recurrences were evaluated by the primary surgeon and reported to the registry. RESULTS: A total of 504 patients treated for cancer were identified in the registry. A minimum follow-up of one year was obtained for 480 of 493 evaluable patients (97.4 percent). Wound recurrence was identified in five patients (1.1 percent). Recurrence status was unknown in 18 patients (3.8 percent). CONCLUSION: Wound recurrence rates appear to be low. Although length of follow-up is limited, patterns of recurrence from previous studies suggest that 80 percent of recurrences should have occurred within one year. Given the limitations of a Phase II study, the hypothesis that recurrence rate is low is supported. However, prospective randomized trials are needed to establish if any difference in wound recurrence rates after laparoscopic or open resection of colorectal cancer exists.

Colectomy↗
PubMed1996

Basal and meal-stimulated colonic absorption.

PURPOSE: Few quantitative experiments evaluating colonic absorption of water and electrolytes have been performed using an awake, conscious animal model. The purpose of these experiments was to develop this type of model and evaluate both basal and meal-stimulated colonic absorption of water and electrolytes. METHODS: Canine Thiry-Vella fistulas were created using a 20 cm segment of distal colon under general anesthesia. Colonic absorption studies were performed using infusion of the Thirty-Vella fistulas with a buffer solution containing [14C]polyethylene glycol. Electrolyte analysis and concentration of radioactivity in the effluent were obtained and used to calculate the net flux of water, sodium, and chloride. Each study consisted of an one-hour basal period and a three-hour experimental period divided into two groups. Group 1 received no meal. Group 2 orally ingested a mixed meal at the completion of the basal hour. RESULTS: In the basal state, water and electrolytes are absorbed from the distal colon at a steady and constant rate. An orally ingested meal produces a statistically significant increase in the rate of absorption, independent of direct colonic luminal contact with the nutrients of the meal given. CONCLUSIONS: These studies demonstrate an in vivo quantitative and qualitative measure of mammalian colonic water and electrolyte absorption. An increase in absorption rate occurs in response to a meal that is probably the result of an unidentified neural or humoral signal.

Animals↗
PubMed1996

Technetium-99m-labeled red blood cell scans in the investigation of gastrointestinal bleeding.

PURPOSE: Technetium-99m-labeled red blood cell scans (Tc99m RBC scan) are recommended to confirm gastrointestinal (GI) bleeding. It is controversial whether these scans are sufficient to localize the site of bleeding. This study evaluated the efficacy of RBC scans in confirming and localizing GI bleeding. Our hypothesis was that these scans were effective in localizing GI bleeding if positive within the continuous phase of imaging. METHOD: Tc99m RBC scans were performed on a total of 80 patients over a four-year period to localize GI bleeding (59 male, 21 female; age range 6-88 (mean, 48) years). Films of 75 of the 80 patients were reread by a nuclear medicine physician who was blinded to the original reading and identity and history of the patient. Results of scans were compared with confirmatory studies. RESULTS: A total of 21 patients had positive scans (28 percent). Of these, the site of bleeding in 16 of 21 patients (76 percent) was confirmed by angiography (4/16), endoscopy (10/16), surgery (10/16), or a combination of these. In 14 of the 16 confirmed studies (88 percent), RBC scan correctly localized site of bleeding by our rigid definition. In six patients (4 not confirmed, 2 erroneously localized), scans were positive only at greater than 15 hours. Ten of the 14 correctly localized studies and none of the incorrectly localized studies were positive in the continuous phase of imaging. CONCLUSION: Tc99m RBC scan is effective in localizing GI bleeding when positive within the continuous phase of imaging. In this population supplemental angiography or endoscopy for the purpose of localization would seem unnecessary.

Adolescent↗
PubMed1996

Surgical outcome in acquired immunodeficiency syndrome patients with non-Hodgkin's lymphoma of the gastrointestinal tract.

PURPOSE: Incidence of non-Hodgkin's lymphoma (NHL) has shown a dramatic increase, concurrent with the epidemic of acquired immunodeficiency syndrome (AIDS). In terms of surgical intervention, management of the patient with AIDS-NHL remains unclear. Purpose of this paper was to determine the role and outcome of surgical intervention in patients with AIDS-NHL of the gastrointestinal (GI) tract. METHODS: Data were obtained by retrospective chart review. RESULTS: From 1980 to 1993, charts of 22 patients with diagnosis of AIDS-NHL of the GI tract who underwent either biopsy or surgical procedure were reviewed. All patients were male, with a mean age of 35.7 years. Sixty-seven biopsies were performed in the 22 patients identified. No morbidity or mortality was associated with any of the biopsy procedures. Major intra-abdominal operations were performed in eight patients, including seven who underwent primary resections of lymphomas. Mean survival for the group as a whole was 18 months, although that for the seven patients undergoing resection was 20.4 months. CONCLUSIONS: Diagnosis of AIDS-NHL of the GI tract should not discourage performance of otherwise appropriate surgical procedures.

Adult↗
PubMed1995

Methylation of the 5' CpG island of the p16/CDKN2 tumor suppressor gene in normal and transformed human tissues correlates with gene silencing.

Loss of heterozygosity on 9p21, where the p16/CDKN2 tumor suppressor and the p15INK4B cell cycle regulator genes are located, is a common genetic alteration in bladder cancer. However, it has been difficult to demonstrate homozygous deletions and intragenic mutations in either of these two genes in primary transitional cell carcinomas (TCC) of the bladder. Similarly, colon cancer-derived cell lines have shown no homozygous deletions of the p16/CDKN2 locus in contrast to a wide variety of tumor-derived cell lines. We have investigated abnormal methylation of the 5' CpG islands of the p16/CDKN2 and p15INK4B genes as an alternative mechanism of inactivation of these genes in bladder and colon cancers. De novo methylation of the 5' CpG island of p16/CDKN2 was observed in 12 of 18 (67%) uncultured bladder TCCs and in 2 of 3 (67%) bladder cell lines. In contrast, only 1 of 10 (10%) colon carcinomas showed methylation of the 5' CpG island of p16/CDKN2. It was striking to find that this region was extensively methylated and the gene not expressed in the normal colonic mucosa of 6 of 10 (60%) patients with colon cancer, whereas 5 of the corresponding colon tumors showed no methylation and high levels of p16/CDKN2 expression. Our data show a significant correlation (P = 0.00001, two-sided) between the absence of p16/CDKN2 expression and methylation of its 5' CpG island in bladder tumors, cell lines, and normal colon mucosa. In contrast, no association was observed between expression and methylation status of the 5' CpG island of p15INK4B. Our results suggest that the p16/CDKN2 tumor suppressor gene may be inactivated by methylation of its 5' CpG island in TCCs of the bladder. We also present evidence of methylation of the 5' CpG island in this autosomal gene in normal colonic tissue.

Base Sequence↗
PubMed1995

Base excision repair of U:G mismatches at a mutational hotspot in the p53 gene is more efficient than base excision repair of T:G mismatches in extracts of human colon tumors.

Approximately 50% of mutations that inactivate the p53 tumor suppressor gene in the germline and in colon tumors are C to T transitions at methylation sites (CpG sites). These mutations are believed to be caused by an endogenous mechanism and spontaneous deamination of 5-methyl-cytosine to T is likely to contribute significantly to this high mutation rate. The resulting T:G mismatches created by this process have been hypothesized to be less efficiently repaired than U:G mismatches formed by deamination of C. We have, therefore, performed the first study to directly compare rates of T:G versus U:G base excision repair at identical sites observed to be mutated in the p53 gene using extracts of human normal colon mucosa and colon carcinoma tissue. Mismatched U was excised up to 6000-fold more efficiently than T, suggesting that differences in repair efficiencies are the major source of C to T transition mutations at CpG sites in human tissues. The data also suggests that T:G mismatches are repaired by additional mechanisms in human cells.

Base Sequence↗
PubMed1995

Pouchitis.

Explore the source record for details and available documents.

Humans↗
PubMed1995

Laparoscopic Bowel Surgery Registry. Preliminary results.

UNLABELLED: Laparoscopic surgery has evolved rapidly since 1989. The American Society of Colon and Rectal Surgeons, the Society of American Gastrointestinal Endoscopic Surgeons, and the American College of Surgeons Commission on Cancer jointly sponsored a registry to identify as early as possible the patterns of practice and acute complications of laparoscopic colectomy. METHODS: Cases were voluntarily registered by community and academic surgeons. Information was entered in the EPI-5 database. RESULTS: One thousand fifty-six cases were contributed by 118 surgeons; 763 patients were completed laparoscopically. The most common indication for surgery was cancer in 453 patients. The right colon (n = 364) and sigmoid (n = 294) were most frequently resected. Respondents felt adequate cancer resections were performed. Although several unique complications were noted, intraoperative complications were similar in type and frequency to open cases. CONCLUSION: Laparoscopic colorectal surgery can be performed with acceptable complications. It remains unclear if this approach is adequate for long-term management of colon and rectal cancer.

Colectomy↗
PubMed1995

Does peritoneal mobilization increase laparoscopic acidosis?

PURPOSE: It was hypothesized that laparoscopic colon surgery may be associated with increased absorption of CO2 resulting from mobilization of lateral peritoneal reflections. METHODS: Six pigs underwent laparotomy with removal of a measured quadrant of peritoneum before insufflation to 15 mmHg with CO2. Six paired control animals also underwent insufflation with CO2 to 15 mmHg. Measurements of the end-tidal CO2 (PetCO2), arterial blood gas analysis for CO2 (PaCO2), and pH were performed before insufflation, at 5 and 10 minutes following insufflation, then at successive 15-minute intervals for a total of two hours, and 15 minutes following desufflation. No attempt was made to correct the hypercarbia by increasing minute ventilation. RESULTS: PaCO2 reached its maximum level at two hours with values of 70.77 +/- 5.54 mmHg and 64.62 +/- 5.18 mmHg in the peritonectomized and control groups, respectively. PetCO2 also peaked at two hours to 60 +/- 13 mmHg for the study group and 54 +/- 11 mmHg for controls. pH reached its nadir at two hours, falling from a baseline of 7.45 +/- 0.08 to 7.23 +/- 0.09 in the study group, and from 7.42 +/- 0.04 to 7.24 +/- 0.04 in the control group. There were no statistically significant differences between the two groups for any of the parameters measured at each time interval. CONCLUSIONS: The hypothesis that peritonectomy produces greater CO2 absorption during CO2 pneumoperitoneum was disproved under these experimental conditions.

Absorption↗