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Biomedical subjects

J R Monson

Publications and source records attributed to J R Monson.

At least 19 recordsLinked to original sources
PubMed1998

Multiple cell populations in colorectal carcinomas: analysis by 3-colour fluorescence in situ hybridization.

A three-colour FISH approach using centromere-specific DNA probes was used to analyse the number of chromosomes 7, 17 and 18 found within individual tumour cells and the results were correlated with total DNA ploidy determined by image analysis. FISH analysis showed a high level of heterogeneity in the majority of tumour samples with only 7 out of 44 samples having a single chromosome profile occurring in greater than 40% of the cells. Analysis of the modal chromosome number showed that a diploid 2/2/2 profile for chromosome 7, 17 and 18 respectively occurred most commonly. The DNA ploidy index for biopsies with a 2/2/2 profile varied between 0.93-2.06. No gain of chromosome was observed in the adenoma samples or Dukes A tumours but a loss of chromosome 18 was seen in 50% of these early carcinomas. A modal chromosome profile of 4/2/2 was commonly found in Dukes B and C tumours suggesting that endoreduplication with the relative loss of chromosome 17 and 18 is common in advanced cancers. The DNA ploidy index for the more advanced tumours was also variable but significantly higher than that found in the early tumours and non-tumour controls. In conclusion, this work shows that tumours are highly heterogeneous and that the majority of tumours consist of a large number of cell sub-populations with respect to the expression of chromosomes 7, 17 and 18.

Adenocarcinoma↗
PubMed1997

Artificial neural networks applied to outcome prediction for colorectal cancer patients in separate institutions.

BACKGROUND: Artificial neural networks are computer programs that can be used to discover complex relations within data sets. They permit the recognition of patterns in complex biological data sets that cannot be detected with conventional linear statistical analysis. One such complex problem is the prediction of outcome for individual patients treated for colorectal cancer. Predictions of outcome in such patients have traditionally been based on population statistics. However, these predictions have little meaning for the individual patient. We report the training of neural networks to predict outcome for individual patients from one institution and their predictive performance on data from a different institution in another region. METHODS: 5-year follow-up data from 334 patients treated for colorectal cancer were used to train and validate six neural networks designed for the prediction of death within 9, 12, 15, 18, 21, and 24 months. The previously trained 12-month neural network was then applied to 2-year follow-up data from patients from a second institution; outcome was concealed. No further training of the neural network was undertaken. The network's predictions were compared with those of two consultant colorectal surgeons supplied with the same data. FINDINGS: All six neural networks were able to achieve overall accuracy greater than 80% for the prediction of death for individual patients at institution 1 within 9, 12, 15, 18, 21, and 24 months. The mean sensitivity and specificity were 60% and 88%. When the neural network trained to predict death within 12 months was applied to data from the second institution, overall accuracy of 90% (95% CI 84-96) was achieved, compared with the overall accuracy of the colorectal surgeons of 79% (71-87) and 75% (66-84). INTERPRETATION: The neural networks were able to predict outcome for individual patients with colorectal cancer much more accurately than the currently available clinicopathological methods. Once trained on data from one institution, the neural networks were able to predict outcome for patients from an unrelated institution.

Bias↗
PubMed1997

Physiology of rectal sensations: a mathematic approach.

PURPOSE: The first awareness of balloon inflation (first sensation (FS)), flatus sensation (constant sensation (CS)), urge to defecate (UD), and maximum tolerated threshold (MTT) are the four commonly evaluated rectal sensations. The traditional view that these sensations are attributable to pelvic floor mechanoreceptor stimulation is challenged by current evidence in favor of rectal wall mechanoreceptors. The aim of this study was to determine the physiology of these sensations, using a dynamic mathematic model of the rectum. METHODS: In a group of 15 healthy adult volunteers (11 female and 4 male; median age, 51.5 (range, 31-74) years), the polynomial behavior of the two smooth muscle components of a dynamic mathematic model of the rectum was analyzed to find strain levels of smooth muscle activity in relation to corresponding strain levels of each of the four "rectal" sensations. RESULTS: Longitudinal and circular smooth muscle relaxation appeared to be the rate detection and signaling mechanisms, respectively. The latter triggered sensations of CS, UD, and MTT. FS was an anal canal sensation, related temporally with onset of rectoanal inhibitory reflex. In vitro validation of the model suggested MTT to be a physiologic protective mechanism associated probably with tetanic smooth muscle contraction. CONCLUSIONS: Evaluation of rectal sensations should be confined to CS and UD because MTT is painful and does not contribute any additional information, and FS is not a true rectal phenomenon.

Adult↗
PubMed1997

Staged delivery of Nd:YAG laser therapy for palliation of advanced rectal carcinoma.

PURPOSE: This study was designed to assess the degree of symptom relief, complication rate, and survival time of patients who undergo palliation with the neodymiumyttrium aluminum garnet (Nd:YAG) laser for advanced rectal cancer. METHODS: Charts of 41 consecutive patients with advanced rectal cancer treated by this method were reviewed. RESULTS: Thirty-three patients received laser treatment for a primary tumor, and eight received laser palliation for local recurrence following previous surgery. Mean number of treatments delivered was 2 (range, 1-6) for patients with a primary lesion and 2 (range, 1-4) for those patients with local recurrence. In patients in whom more than one delivery was required, subsequent procedures were deferred for more than six weeks. Morbidity rate was 2 percent, with no procedure-related mortality. Median survival time was 19 (range, 1-60) months for patients with a primary tumor and 7 (range, 3-38) months for patients with local recurrence. Four patients subsequently elected to undergo palliative surgery, and five other patients had a loop colostomy formed because of large-bowel obstruction after a mean of 24 (range, 18-41) months. Nd:YAG laser treatment offered adequate laser palliation for 78 percent of patients in this series. However, patients who survive for more than 24 months after their first laser treatment are more likely to require palliative surgery. CONCLUSIONS: The majority of patients undergoing laser ablation for palliation do not require large numbers of treatment sessions. By delaying the interval between treatments, morbidity and mortality rates are negligible. Most patients avoid a stoma or defer the date of requiring one before their death with this therapy.

Aged↗
PubMed1997

Feasibility study for use of brush cytology as a complementary method for diagnosis of rectal cancer.

UNLABELLED: Brush cytology has previously been described as a feasible method for accurately diagnosing colorectal cancer. PURPOSE: This study was designed: 1) to determine the sensitivity and specificity of brush cytology for the diagnosis of rectal cancer; 2) to prospectively assess the extent of interobserver variability with this technique; 3) to prospectively examine the cost impact of the addition of brush cytology as a routine method of confirming the diagnosis of rectal cancer. PATIENTS AND METHODS: Three hundred fifty-seven patients who attended a rectal clinica and who were found to have a lesion between January 1990 and March 1996 were assessed. Each patient underwent rigid proctoscopy, followed by brush cytology and tissue biopsy. Results were compared with the final histologic diagnosis in each patient. The brushings from the last 92 consecutive patients in this series were independently examined by four cytologists and a pathologist to determine the rate of interobserver variability. RESULTS: Rectal adenocarcinoma was confirmed from surgically resected specimens in 303 patients. Brush cytology accurately diagnosed 278 of them. Of the remaining 25 patients, two had brushings that were insufficient for diagnosis. There was one false-positive case. Forceps biopsy correctly identified cancer in 260 patients, with no false-positive interpretations. Brush cytology accurately identified 53 of 54 adenomas as being benign, and forceps biopsy correctly identified all as benign. Sensitivity of brush cytology in this series was 92 percent, with a specificity of 92 percent. Interobserver agreement was 84 percent. Actual costs incurred with this method was an additional $17.00 per patient. CONCLUSIONS: Brush cytology can accurately diagnose rectal cancer in a high proportion of patients. Interobserver variation is low and compares favorably with other forms of cytologic interpretation. The additional cost remains a concern but can be kept within acceptable proportion.

Adenoma↗
PubMed1997

Incremental elastic modulus--a challenge to compliance.

Rectal compliance has theoretical and practical drawbacks resulting in wide variation in the reported normal values. Slope of stress-strain relation, a measure of rectal wall stiffness (Incremental elastic modulus; IEM) may be an effective alternative. The aim of this study was to compare IEM with rectal compliance during ramp inflation. In a group of 15 normal adults [Median age 51.5 years (range 31 to 74); 11 female and 4 male], these parameters were assessed at three rates of inflation, using a proctometrogram-catheter-balloon (PCB) complex and endorectal ultrasound scanner (7 Mhz; B & K) to measure intrarectal pressure and radius respectively. IEM had a linear relation with strain (Slope 33.55; R2 = 0.9815) in contrast to compliance (R2 = 0.0088). Series elastic component (SEC), a measure of passive viscoelasticity, was rate independent elasticity [Slope 1.02 (0.98 to 1.15); P = ns] and a rate dependent viscosity (P = 0.004; One way ANOVA). Both IEM and SEC were reproducible (R = 0.985; P < 0.01). This study emphasises the importance of rectal wall viscoelastic evaluation based on stress and strain rather than compliance.

Adult↗
PubMed1997

The optimum bowel preparation for flexible sigmoidoscopy.

With the proposed introduction of a flexible sigmoidoscopic screening programme for colorectal cancer, patient compliance is of paramount importance. Therefore, the bowel preparation providing optimum cleansing of the bowel with the least associated discomfort and inconvenience for the patient must be found. Patients were randomized to receive either Picolax the evening before the examination or self-administered Fleet enemas prior to the investigation. The endoscopist and nurse practitioner who collected data on a standard questionnaire were blinded to the preparation used. Bowel preparation was graded by the endoscopist as: excellent, good, adequate or poor. One hundred and two consecutive patients were randomized: 56 to the Fleet enema group and 46 to the Picolax group. Self-administered Fleet enemas provided a significantly superior bowel preparation with 52 (93%) being judged adequate or better, as opposed to 34 (74%) in the Picolax group. In addition, Fleet enemas were associated with significantly fewer adverse associated symptoms: 11 (20%) vs 24 (52%). Patients reported to be willing to receive Fleet enemas again in 53 (95%) vs 37 (80%) for the Picolax group. The self-administered Fleet enema is superior to Picolax in terms of bowel preparation for flexible sigmoidoscopy and the incidence of associated adverse symptoms.

Administration, Oral↗
PubMed1997

Preoperative staging of rectal carcinoma by magnetic resonance imaging with a pelvic phased-array coil.

BACKGROUND: The use of surface coils for magnetic resonance imaging (MRI) allows enhanced image definition and so potentially more accurate staging of colorectal cancer. Endorectal coil imaging is invasive, operator dependent and impossible in a high proportion of patients due to rectal stricture. The phased-array pelvic coil, however, is non-invasive and applicable to all rectal tumours. METHODS: A pelvic phased-array coil was used for preoperative MRI staging of 38 primary rectal carcinomas. Results were expressed according to the Dukes and tumour nodes metastasis (TNM) classifications. After resection of the tumour, the stage predicted on MRI was compared with the pathological classification. RESULTS: The overall accuracy of preoperative staging with the pelvic phased-array coil was 55 per cent for both Dukes class and T stage. Assessment of nodal involvement gave an overall accuracy for MRI of 76 per cent with a sensitivity of 57 per cent and specificity of 88 per cent. CONCLUSION: Use of a pelvic phased-array coil did not improve the staging accuracy of MRI to a clinically useful level.

Adult↗
PubMed1997

Monoclonal antibody treatment of colorectal cancer.

BACKGROUND: The recent development of adjuvant monoclonal antibody immunotherapy for patients suffering from colorectal cancer has led to a re-evaluation of the role of these molecules in the treatment of solid tumours. In particular, interest has been directed at identifying appropriate candidates for therapy, evaluating treatment schedules and developing new molecules of therapeutic potential. METHODS: This is a review of published data on patients undergoing antibody therapy. In addition, current theories of the mechanism of action of antitumour monoclonal antibodies are presented, along with potential future therapeutic approaches. RESULTS AND CONCLUSION: Monoclonal antibody-based adjuvant therapy of colorectal cancer appears to be effective; international multicentre trials continue. The development of new molecules, such as chimaeric antibodies, offers the potential of increased tumour targeting with reduced toxicity. Such molecules may be used alone or in combination with agents such as chemotherapy or cytokines.

Antibodies, Monoclonal↗
PubMed1997

n-Butyl cyanoacrylate adhesive for skin closure of abdominal wounds: preliminary results.

Tissue adhesives offer significant potential advantages over traditional methods of wound closure. A new n-butyl 2-cyanoacrylate adhesive formulation was utilised for the closure of abdominal wounds after general and laparoscopic gastrointestinal surgery. One hundred and two patients with 240 wounds were recruited. Wounds were classified as > 10 cm, n = 39; 5-9 cm, n = 27; and < 5 cm, n = 176. Complications included one small seroma and two partial superficial dehiscences. There were no incidences of wound infection. This preliminary study indicates that this tissue adhesive can safely and effectively be utilised for general abdominal wound closure. It should now be subjected to the rigorous of a randomised controlled trial to compare its performance against the more traditional methods of wound closure.

Dermatologic Surgical Procedures↗
PubMed1996

Randomized trial of blunt-tipped versus cutting needles to reduce glove puncture during mass closure of the abdomen.

Eighty-five consecutive patients were randomized to undergo mass closure of the abdomen with no. 1 polydioxanone mounted on either a blunt-tipped (n = 46) or cutting (n = 39) needle. Gloves were changed before closure and tested for perforation afterwards using standard air or water techniques. Fourteen pairs of gloves were punctured when using a cutting needle, and three pairs when a blunt-tipped needle was used. The majority of punctures were to the non-dominant glove. The surgeon was aware of the puncture in eight of the 14 instances involving a sharp needle and in one of the three involving a blunt-tipped needle. Blunt-tipped needles, while not eliminating the risk, significantly reduced the incidence of surgical glove puncture (P < 0.001, Fisher's exact test). The use of cutting needles for abdominal closure should be abandoned.

Abdomen↗