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Michael J Solomon

Publications and source records attributed to Michael J Solomon.

At least 37 records · Page 2Linked to original sources
PubMed2004

Effect of monomer geometry on the fractal structure of colloidal rod aggregates.

The fractal structure of clusters formed by diffusion-limited aggregation of rodlike particles is characterized over three decades of the scattering vector q, and displays an unexpected dependence on the aspect ratio of the constituent monomers. Monte Carlo simulations of aggregating Brownian rods corroborate the experimental finding that the measured fractal dimension is an increasing function of the monomer aspect ratio. Moreover, increasing the rod aspect ratio eliminates the structural distinction between diffusion- and reaction-limited cluster aggregation that is observed for spheres.

Journal Article↗
PubMed2004

Free colorectal cancer cells on the peritoneal surface: correlation with pathologic variables and survival.

BACKGROUND: Clinicopathologic staging of colorectal cancer remains the best predictor of survival. Prognostication for an individual with colorectal cancer remains elusive. This study was designed to investigate the incidence of free surface colorectal cancer cells detected by cytology during elective open curative resection, to correlate their presence with particular clinicopathologic variables and determine whether their presence was predictive of cancer-specific survival. METHODS: Over a six-year period in one institution, all elective colon and intraperitoneal rectal cancer specimens were assessed during primary resection for the presence of free colorectal cancer cells by means of a simple and tested specimen imprint cytology methodology. Clinicopathologic variables were assessed prospectively and blinded to cytology results. All patients were followed up routinely until death and if the patient was not seen within the last six months, information was obtained from the New South Wales Registry of Births, Deaths and Marriages in Australia. RESULTS: Overall, 26 of 281 (9.25 percent) colorectal cancers had positive cytology for cancer cells on the peritoneal surface of the bowel. Poorly differentiated tumors were significantly associated with positive cytology. Tumor penetration, presence of vascular or neural invasion, mucinous characteristics, lymph node status, and operative procedure performed were not statistically significant predictors of positive cytology. Overall, 43 of the 281 patients (15.3 percent) died during the mean follow-up period of 49.2 months from cancer-related deaths. Of these patients, 8 had positive cytology and 35 had negative cytology results. Cancer-specific survival assessed with the log-rank test was significantly associated with positive cytology in univariate (P = 0.008) and multivariate analysis (P < 0.001). CONCLUSION: In this study, the presence of free surface colorectal cancer cells has been shown to be predictive of survival and is independent of direct peritoneal invasion and lymph node status. Thus, further assessment of this simple prognostic variable is warranted and selection of patients with positive cytology for possible adjuvant therapies may be beneficial.

Adenocarcinoma↗
PubMed2004

Laparoscopic versus open ileocolic resection for Crohn's disease.

OBJECTIVE: Laparoscopic ileocolic (LI) resection for Crohn's disease has several potential advantages over the traditional open technique. The objective of this study was to compare early surgical outcomes in patients having laparoscopic versus open ileocolic resections for Crohn's disease. METHODS: Data collected prospectively from 21 patients having LI resection for Crohn's disease between 1995 and 2001 were compared to data from 19 patients having open ileocolic resection for Crohn's disease between 1990 and 1995. RESULTS: Patients in both groups had similar ages, sex distribution, and rates of previous abdominal surgery. Mean operating time was not significantly different between the groups. There was a nonsignificant trend to less postoperative analgesic requirement in the laparoscopic group. Resumption of liquid (P <.001) and solid (P =.01) diet, return of bowel function [flatus (P =.008), feces (P =.008)] and time to discharge (P =.001) all occurred significantly more quickly in the laparoscopic group. There was no difference in the rates of morbidity between the two groups. CONCLUSIONS: LI resection for Crohn's disease appears to be safe and has comparable if not superior results to open surgery in the short term.

Adult↗
PubMed2003

Self-diffusion in dilute colloidal suspensions with attractive potential interactions.

The colloidal short-time self-diffusivity D(s)(s)(phi) is significantly retarded relative to hard sphere suspensions for the case of interparticle potential interactions induced by a nonadsorbing polymer. A comparison of diffusing wave spectroscopy measurements with direct calculations of D(s)(s)(phi) demonstrates that depletion effects on structure explain the observed retardation. We show that coexistence boundaries place unexpectedly severe constraints on the amount of D(s)(s)(phi) retardation possible for stable suspensions. The measured retardation is demonstrated to be an indicator of suspension metastability.

Journal Article↗
PubMed2003

p53, deleted in colorectal cancer gene, and thymidylate synthase as predictors of histopathologic response and survival in low, locally advanced rectal cancer treated with preoperative adjuvant therapy.

PURPOSE: Adjuvant therapy, either preoperatively or postoperatively, and modifications of surgery have been used to try to improve outcome of surgery for rectal cancer in regard to both local recurrence and survival. Assessment of prognosis in patients after resection is currently primarily based on clinicopathologic factors. These predict the subsequent behavior of the tumor only imperfectly. The aim of this study was to evaluate three potential molecular genetic markers of prognosis (p53, deleted in colorectal cancer gene, and thymidylate synthase) in Dukes Stage B and C low rectal tumors treated with adjuvant therapy and to determine whether they correlate with survival, local recurrence, or the pathologic response to adjuvant therapy (assessed by extent of tumor regression and tumor down-staging). METHODS: Sixty locally advanced low rectal tumors resected after preoperative chemoradiotherapy or radiotherapy alone were studied by immunohistochemical staining for p53, deleted in colorectal cancer gene, and thymidylate synthase. In addition, p53 gene mutations were sought by polymerase chain reaction-single-strand conformation polymorphism analysis. These results were correlated with survival, local recurrence, and pathologic response to adjuvant therapy. RESULTS: Lack of thymidylate synthase staining by immunohistochemistry was associated with tumor down-staging after preoperative chemoradiotherapy but not after radiotherapy or for these two combined groups. There was no correlation between p53, deleted in colorectal cancer gene, or thymidylate synthase immunohistochemical staining or between p53 polymerase chain reaction-single-strand conformation polymorphism and local recurrence or survival in locally advanced low rectal cancers treated with preoperative adjuvant therapies. CONCLUSION: Prediction of prognosis in patients with locally advanced low rectal cancers treated with preoperative adjuvant therapies continues to be problematic. Thymidylate synthase immunohistochemistry appears to be the most promising factor of those assessed in predicting tumor down-staging after preoperative chemoradiotherapy for locally advanced low rectal cancers.

Adenocarcinoma↗
PubMed2003

Randomized, controlled trial of biofeedback with anal manometry, transanal ultrasound, or pelvic floor retraining with digital guidance alone in the treatment of mild to moderate fecal incontinence.

BACKGROUND: A prospective, three-armed, randomized, controlled trial was performed to assess whether pelvic floor exercises with biofeedback using anal manometry or transanal ultrasound are superior to pelvic floor exercises with feedback from digital examination alone in terms of continence, quality of life, physiologic sphincter strength, and compliance. Its secondary objectives were to assess whether there are any differences in these outcomes between biofeedback with transanal ultrasound vs. anal manometry and to correlate the physiologic measures with clinical outcome. METHODS: One hundred twenty patients with mild to moderate fecal incontinence were randomized into one of three treatment groups: biofeedback with anal manometry, biofeedback with transanal ultrasound, or pelvic floor exercises with feedback from digital examination alone. Commencing one week after an initial 45-minute assessment session, patients attended monthly treatments for a total of five sessions. Each session lasted 30 minutes and involved sphincter exercises with biofeedback that involved instrumentation or digital examination alone, and patients were encouraged to perform identical exercises twice per day between outpatient visits. RESULTS: One hundred two patients (85 percent) completed the four-month treatment program. Across all treatment allocations, patients experienced modest but highly significant improvements in all nine outcome measures during treatment, with 70 percent of all patients perceiving improvement in symptom severity and 69 percent of patients reporting improved quality of life. With the possible exception of isotonic fatigue time, there were no significant differences between the three treatment groups in compliance, physiologic sphincter strength, and clinical or quality-of-life measures. Correlations between physiologic measures and clinical outcomes were much stronger with ultrasound-based measures than with manometry. CONCLUSIONS: Although patients in this study who completed pelvic floor exercises with feedback from digital examination achieved no additional benefit from biofeedback and measurement with transanal ultrasound or manometry, it may be that the guidance received through digital examination alone offered patients in the pelvic floor exercise group an effective biofeedback mechanism. Contrary to our hypothesis, the use of transanal ultrasound offered no benefit over manometry, but the use of ultrasound for isotonic fatigue time and isometric fatigue contractions provided potentially important physiologic measures that require further study. This study has confirmed, through a large sample of patients, that pelvic floor retraining programs are an effective treatment for improving physiologic, clinical, and quality-of-life parameters in the short term.

Aged↗
PubMed2003

Cholecystectomy in patients with Crohn's ileitis.

PURPOSE: Gallstone disease is reported to be higher in patients with Crohn's disease than in the general population. This study was designed to determine the prevalence of cholecystectomy in patients with Crohn's ileitis, attempt to identify any associated risk factors, and determine whether it is justified to perform prophylactic cholecystectomy during ileocolic resection. METHODS: A total of 191 patients with Crohn's ileitis who were treated medically or who had an ileocolic resection were retrospective reviewed. A questionnaire survey was performed. Telephone interviews were conducted for the non respondents. Further review of medical records was performed to determine the details of admissions for any gallstone disease and/or subsequent cholecystectomy. A control group matched for age and gender was obtained. RESULTS: A total of 191 questionnaires were mailed, and the overall response rate was 70.2 percent (134/191) after telephone interview follow-up. There were 2 of 45 medical and 18 of 89 surgical patients with symptomatic cholelithiasis, i.e., 14.9 percent (20/134) of respondents. As a result, 2 patients (1.5 percent) required endoscopic sphincterotomy, 17 patients (12.7 percent) needed cholecystectomy, and 1 patient (0.7 percent) did not have any intervention. Only five patients had a cholecystectomy after their ileal resections. In the control group of 150 patients, 15 patients (14 females; mean age, 51.9 years; range, 34-78 years) had previous cholecystectomy. There was no significant difference with prevalence of cholecystectomy in Crohn's patients compared with controls (17/134 vs. 15/150; P = not significant). Furthermore, the number of ileal resections did not affect the cholecystectomy rate, but patients who had >30 cm of ileum resected were more likely to have cholecystectomy (P = 0.056). CONCLUSIONS: The prevalence of gallstone disease in Crohn's ileitis requiring cholecystectomy is similar to that of the general population with a female predominance. In addition, the number of patients requiring cholecystectomy after ileal resection was low. Thus, synchronous prophylactic cholecystectomy during ileocolic resection for Crohn's ileitis is not justified.

Adolescent↗
PubMed2003

Improving the evidence base in surgery: sources of bias in surgical studies.

Clinical epidemiology, which is concerned with the application of epidemiological principles to patient care, provides the scientific basis for evidence-based medicine. The present paper reviews the epidemiological concepts of selection bias, measurement bias and confounding in surgical research and discusses ways in which these sources of bias can be minimized in surgical studies.

Bias↗
PubMed2003

Improving the evidence-base in surgery: evaluating surgical effectiveness.

This second of two articles about clinical epidemiology reviews the generation and synthesis of evidence for the effectiveness of surgical procedures. While well-designed randomized controlled trials of surgical procedures are considered the 'gold standard' of evaluation design, they may achieve high internal validity at the expense of external validity (generalizability). Improving the -evidence-base in surgery likely will require a comprehensive approach to surgical outcomes assessment, involving both improvements in the quality and quantity of randomized controlled trials as well as recognition of the complementary role of alternate study designs.

Algorithms↗
PubMed2003

Measuring the importance of attributes that influence consumer attitudes to colorectal cancer screening.

BACKGROUND: The aim of the present study was to rate the importance of attributes of screening for bowel cancer. METHOD: Randomly selected households in central Sydney were contacted to identify men and women aged 50-70 years who were then asked to complete a self-administered questionnaire about bowel cancer screening and related issues. Seven hundred and ninety-one residents (362 men and 429 women) returned questionnaires. Respondents were asked to rate the extent to which each of 34 attributes would encourage them to participate in bowel cancer screening. RESULTS: The three most highly rated attributes were: if the test was recommended by their general practitioner (GP; 94% either 'strongly agreed' or 'agreed'); if the test identified early cancers (92%); and if the test would avert a premature death due to bowel cancer (90%). Having a friend or relative with bowel cancer (61%), advertising (41%) or famous people promoting the program (62%) were less influential. Respondents who were unemployed or on a pension were less likely to participate in screening than those who were employed if there was an 'out of pocket' charge of 15.00 Australian dollars (chi 2 = 7.56, 2df, P = 0.006). Respondents with higher levels of education were significantly more concerned than respondents with lower levels of education about test accuracy (chi 2 = 15.76, 2df, P < 0.001), its availability from their local chemist (chi 2 = 16.96, 2df, P < 0.001), being able to return the test kit by post (chi 2 = 21.9, 2df, P < 0.001) or deposit it with their local chemist (chi 2 = 10.0, 2df, P < 0.01). They were also less likely to be influenced by a famous person promoting bowel cancer screening (chi 2 = 18.87, 2df, P < 0.001). CONCLUSIONS: Our results endorse the role of the GP in bowel cancer screening. However, the study also has demonstrated that test accuracy, the convenience of the screening service and notification of test results are valued differently by subgroups in the community, according to their level of education.

Age Factors↗
PubMed2003

An economic perspective on evidence-based patient choice in surgery.

The aim of the present paper is to provide an economic perspective on current and emerging issues relating to surgical decision-making. The central issue discussed in the paper is choice and how this relates to patient management. The paper explores three factors that may influence the nature of choice; they are--evidence-based medicine, patient involvement in making choices and the role of cost-effectiveness analysis in surgery. Together, these factors are driving a shift from the traditional model of care based on medical beneficence to one based more on individual patient autonomy. This shift has been described as a move towards 'evidence-based patient choice' (EBPC). The concept of EBPC is relatively new and ill defined. Yet it encapsulates what is happening now and what will occur more dramatically in the future; that is, the nature of the relationship between surgeon and patient is changing. We hope that this paper will provoke discussion on the concept of EBPC and cost-effectiveness analysis in surgical decision-making.

Choice Behavior↗
PubMed2003

Patient entry into randomized controlled trials of colorectal cancer treatment: factors influencing participation.

BACKGROUND: The objective of this study was to investigate willingness to participate in hypothetical surgical randomized controlled trials (RCTs) among patients and clinicians, who answered as if they themselves were patients. METHODS: We interviewed consecutive patients with colorectal cancer admitted for surgery at a tertiary center in Sydney, Australia. We mailed a questionnaire to all colorectal surgeons and medical oncologists in Australia. RESULTS: Overall, 42% (95% CI, 32% to 52%) of patients, 44% (95% CI, 29% to 60%) of surgeons, and 63% (95% CI, 53% to 72%) of oncologists were willing to enter a randomized clinical trial. Oncologists were significantly more likely to participate than either surgeons (P <.001) or patients (P =.001). No significant associations were seen between willingness to participate and patient characteristics. "Risk of cancer recurrence" was rated by the most patients and doctors as an important reason for refusal of trial entry, although patients additionally identified dislike of randomization and quality of life concerns as important barriers. CONCLUSION: More than 40% of patients were willing to enter into a hypothetical RCT involving surgery. Aversion to randomization and perceptions of differential impact of treatment on cancer recurrence and quality of life are likely to be major barriers to patient accrual in trials of colorectal cancer treatment.

Aged↗
PubMed2003

What do patients want? Patient preferences and surrogate decision making in the treatment of colorectal cancer.

PURPOSE: Clinicians often make decisions for their patients, despite evidence that suggests that correspondence between patient and clinician decision making is poor. The management of colorectal cancer presents difficult decisions because the impact of treatment on quality of life might overshadow its survival efficacy. This study investigated whether patients are able to trade survival for quality of life as a means to express their preference for treatment options and to compare their preferences with those expressed by clinicians. METHODS: Patients undergoing curative surgery for colorectal cancer were interviewed postoperatively to elicit their preferences in four hypothetical treatment scenarios. A questionnaire was mailed to all Australian colorectal surgeons and medical oncologists that asked them to respond as if they themselves were patients. RESULTS: One hundred patients (91 percent), 43 colorectal surgeons (77 percent), and 103 medical oncologists (50 percent) participated. In all four scenarios, patients were able to trade survival for quality of life. Patients' responses varied between scenarios, both in willingness to trade and the average amount traded. There were significant differences between patients and clinicians. Clinicians were more willing than patients to trade survival to avoid a permanent colostomy in favor of chemoradiotherapy. Patients' strongest preference was to avoid chemotherapy, more than to avoid a permanent colostomy. CONCLUSIONS: Patients are able to trade survival as a measure of preference for quality of life and can do so differentially between treatment scenarios. Patients' preferences do not always accord with those of clinicians. Unless patients' preferences are explicitly sought and incorporated into clinical decision making, patients may not receive the treatment that is best for them.

Attitude of Health Personnel↗
PubMed2002

Probe size effects on the microrheology of associating polymer solutions.

Diffusing wave spectroscopy has been used to investigate the thermally driven displacement of colloidal particles dispersed in solutions of associating polymers (APs). The effect of varying colloidal probe size on the measured particle displacements is studied in particular. Recent theories of microrheology are examined in light of the observed effects. The associating polymer used in this research was a linear polyethylene oxide (PEO) chain (molecular weight 35 000 g/mole) with a Cl14 aliphatic group appended to each end of the PEO. Above a critical concentration, the associating polymers display linear viscoelasticity consistent with the Maxwell model. The concentration of aqueous AP solutions was varied from 0.25 to 4.0 wt. %. At low concentration of APs, the mean square displacement of the colloidal beads was indistinguishable from simple Brownian diffusion in the aqueous solvent. However, at concentrations greater than 0.5 wt. %, the mean square displacement differed from simple diffusion in a way that was found to be consistent with the Maxwell model linear viscoelasticity (LVE) of the AP solutions. Significantly, for the most concentrated solutions, as the probe particle size was varied from 0.3 to 2.2 microm, the observed mean square displacement deviated substantially from the generalized Stokes-Einstein behavior predicted by microrheological theories. Our experiments showed that these deviations could not be attributed to specific physicochemical interactions at the probe-matrix interface, since observed mean square displacements were independent of different probe surface chemistries studied. Moreover, this particle size effect was not observed in semidilute, high molecular weight PEO solutions (molecular weight 4.0 x 10(6) g/mole). We concluded that possible effects of AP network compressibility and AP depletion at the probe surface could not account for the observed particle size effects. We examined recent reports of the structural heterogeneity in AP solutions for their possible connection to our observation of the breakdown of the generalized Stokes-Einstein equation for this system. Numerical conversion of the microscopic results to the linear viscoelastic moduli, G'(omega) and G"(omega), by means of a constrained regularization method (CONTIN), demonstrates that the experiments with larger probe particles are most consistent with the single-mode Maxwell model LVE observed by macroscopic mechanical rheology.

Journal Article↗
PubMed2002

Crohn's disease: in defense of a microvascular aetiology.

BACKGROUND AND AIMS: There appears little doubt that microvascular ischaemia is involved in Crohn's disease. Studies have consistently demonstrated that the number of blood vessels and the total volume of blood feeding segments of bowel with Crohn's disease are reduced. However, the aetiology of the microvascular ischaemia is yet to be determined. Potential aetiological factors that appear to be disease specific include increased mesenteric platelet aggregation and increased platelet surface expression of P-selectin and GP53. However, there are several other factors known to be raised in active and quiescent disease for which disease specificity is not yet known, including increased submucosal endothelial endothelin-1 receptor expression, increased m RNA expression for several interleukins and cytokines including TNFalpha, increased PAF and thrombomodulin and finally altered cellular adhesion molecule expression. CONCLUSION: Proving cause and effect will always be a difficult task given the self-perpetuating nature of the inflammatory and coagulation cascades and our inability at present to identify persons who subsequently develop Crohn's disease at a point prior to mucosal inflammation. Results to date however, are supportive of each of these factors, alone or in combination playing an integral part in the development of microvascular ischaemia, a pathological process which appears to precede the classic changes which characterize Crohn's disease.

Blood Viscosity↗
PubMed2002

Management of patients with colorectal cancer: do Australian surgeons know the scientific evidence?

HYPOTHESIS: Not all Australian surgeons are aware of the status of the current evidence for the management of colorectal cancer. DESIGN: Postal survey of Fellows of the Royal Australasian College of Surgeons. PARTICIPANTS: One hundred ninety-five surgeons (127 general surgeons and 68 subspecialist colorectal surgeons) from a response fraction of 89%. MAIN OUTCOME MEASURES: Overall awareness score for 23 clinical recommendations and a subscore for 10 of these for which evidence is compelling rather than inconclusive (9 for and 1 against incorporation in clinical practice). RESULTS: Although no surgeon indicated the status of the evidence correctly for all 23 items, 61% of respondents correctly identified 12 or more items. Surgeons who practiced in capital cities had significantly higher scores than those who practiced outside cities (beta =.16; B = 1.01; 95% confidence interval [CI], 0.14-1.89; P =.02). Surgeons who had been in practice for relatively more years had significantly lower scores than younger surgeons (beta = -.17; B = -0.059; 95% CI, -0.11 to 0.01; P =.02). Surgeons involved in research had significantly higher scores (beta =.18; B = 1.11; 95% CI, 0.23-1.99; P =.01), as did those respondents who had been involved in guideline development (beta =.18; B = 1.42; 95% CI, 0.24-2.63; P =.02). Subscores showed a significantly greater awareness of compelling evidence (level I or level II) (P<.001). There was no relationship between awareness of the evidence for adjuvant therapy and surgeons' perceptions of the usefulness of guidelines about this aspect of clinical management. CONCLUSIONS: Our innovative preguidelines survey has shown that not all surgeons were aware of the evidence underpinning the management of colorectal cancer, affirming the need for guidelines. Predictors of low awareness could be used to target efforts to disseminate and implement guidelines.

Adult↗
PubMed2002

Long-term outcomes of pelvic floor exercise and biofeedback treatment for patients with fecal incontinence.

PURPOSE: The aim of this study was to assess the long-term clinical and quality of life outcomes for patients after referral to a four-month treatment program for fecal incontinence based on pelvic floor exercises and biofeedback. Secondary objectives were to document patients' subsequent treatment activities and their perception of the biofeedback training; to establish the long-term outcomes and initial predictors for the subset of patients who did not complete the treatment, or who failed to improve during the program; and to correlate changes in clinical outcome measures and quality of life over time. METHODS: Patients were contacted by telephone to determine their perception of progress subsequent to the treatment program, any subsequent treatment or activities relating to their fecal incontinence, and which aspect of the treatment program they believed was most helpful. St. Mark's and Pescatori fecal incontinence scores were also recorded, along with patients' self-assessments of their incontinence severity and quality of life. RESULTS: Eighty-three (69 percent) patients were contacted for interviews at a median of 42 (range, 26-56) months after program completion. At the time of follow-up, patients who completed the program continued to enjoy strongly significant improvements in all outcome measures, with 75 percent perceiving a symptomatic improvement and 83 percent reporting improved quality of life. For many patients, improvement continued subsequent to program completion. Patients whose incontinence scores became worse during treatment still reported improvement in their quality of life and perceived incontinence severity during the same time period; many experienced some degree of "catch-up" in their continence scores during the follow-up period. Fourteen patients (17 percent) went on to have surgery for fecal incontinence; of these, 6 (7 percent) had a stoma. Twenty (24 percent) regularly took antidiarrheal medication. Thirty program completers (41 percent) were continuing pelvic floor exercises. CONCLUSIONS: This study confirms the long-term improvement in fecal incontinence achieved through treatment with biofeedback and pelvic floor exercises. In this study, patients also continued to improve after treatment completion, possibly because of the strong emphasis placed on patients during treatment to continue the pelvic floor exercises on their own. The poor correlation between quality of life and quantitative scores of fecal incontinence suggests that there are important aspects of continence that are not being appropriately recognized.

Adult↗