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Biomedical subjects

J H Anderson

Publications and source records attributed to J H Anderson.

At least 19 recordsLinked to original sources
PubMed2006

The presence of a systemic inflammatory response predicts poorer survival in patients receiving adjuvant 5-FU chemotherapy following potentially curative resection for colorectal cancer.

There is increasing evidence that the presence of a systemic inflammatory response plays an important role in survival following curative resection for colorectal cancer. The present study evaluated the relationship between C-reactive protein concentrations and survival in a cohort of patients receiving adjuvant 5-fluorouracil (5-FU) chemotherapy following potentially curative resection for colorectal cancer. In all, 222 patients undergoing potentially curative resection for colorectal cancer were studied. Of these, 50 patients received adjuvant 5-FU-based chemotherapy. Circulating concentrations of C-reactive protein were measured prior to surgery. The minimum follow-up was 15 months; the median follow-up of the survivors was 38 months. During this period 61 patients died, 32 patients of their cancer and 29 of intercurrent disease. In those patients who did not receive adjuvant chemotherapy, age (P < 0.001), Dukes stage (P < 0.05) and an elevated C-reactive protein (P < 0.01) were significantly associated with survival. In those patients who did receive adjuvant chemotherapy, an elevated C-reactive protein concentration (P < 0.01) was significantly associated with survival. The presence of a systemic inflammatory response is an independent predictor of poor outcome in patients receiving adjuvant 5-FU-based chemotherapy following potentially curative resection for colorectal cancer.

Adenocarcinoma↗
PubMed2005

Tactile VR for hand-eye coordination in simulated PTCA.

Percutaneous transluminal coronary angioplasty (PTCA) is a minimally invasive image-guided technique for treatment of coronary diseases. PTCA procedure requires physicians to have good skills of hand-eye coordination in performing the operation. Training of PTCA thus very much emphasizes skill building for hand-eye coordination. We have been developing virtual reality (VR) technology for medical simulation. In this paper, we will address the issue of VR-based simulation for the enhancement of hand-eye coordination for PTCA operation. Starting from the characterization of PTCA procedure, we examine what roles VR can play in training of PTCA physicians. We then describe a computerized PTCA training system we have developed which is composed of a tactile interface and a visual interface. The system is designed in such a way that real PTCA devices (including catheters and guide-wires) can be used to mimic the requirements of the CathLab. The backend computational engine supporting the real-time and realistic PTCA simulation is also presented.

Angioplasty, Balloon, Coronary↗
PubMed2005

Prospective study of the effect of rectopexy on colonic motility in patients with rectal prolapse.

BACKGROUND: Patients with rectal prolapse have abnormal hindgut motility. This study examined the effect of rectal prolapse surgery on colonic motility. METHODS: Twelve patients undergoing sutured rectopexy were studied before and 6 months after surgery by colonic manometry, colonic transit study and clinical assessment of bowel function. The results were compared with those from seven control subjects. RESULTS: Before surgery colonic pressure was greater in patients than controls (P < 0.050). Controls responded to a meal stimulus by increasing colonic pressure; this increase was absent in patients. After rectopexy, colonic pressure reduced towards control values and patients' colonic pressure response to a meal returned. High-amplitude propagated contractions (HAPCs) were seen in all controls but in only three patients before and two patients after surgery. Three patients had prolonged colonic transit before and eight after rectopexy. CONCLUSION: Patients with rectal prolapse have abnormal colonic motility associated with reduced HAPC activity. Rectopexy reduces colonic pressure but fails to restore HAPCs, reduce constipation or improve colonic transit. These observations help explain the pathophysiology of constipation associated with rectal prolapse.

Adult↗
PubMed2005

Accuracy of thin section magnetic resonance using phased-array pelvic coil in predicting the T-staging of rectal cancer.

Magnetic resonance (MR) imaging may contribute to staging rectal cancer and inform the decision regarding administration of pre-operative radiotherapy. The accuracy of MR has been debated. The aim of the present study was to determine the accuracy of thin section T2-weighted MR images in rectal cancer patients. MR results were compared with histological assessment of resection specimens. Over a 2-year period, 42 patients were studied. Histological staging was pT2 n = 13, pT3 n = 25 and pT4 n = 4. MR diagnostic accuracy was 74%. MR sensitivity and specificity was 62% and 79% for pT2 lesions, 84% and 59% for pT3 lesions and 50% and 76% for pT4 lesions. Estimation of tumour penetration by thin section MR imaging of rectal cancers using pelvic phased-array coil has moderate diagnostic accuracy. The limitations of MR should be acknowledged when selecting rectal cancer patients for pre-operative radiotherapy.

Adenocarcinoma↗
PubMed2004

Strategy for selection of type of operation for rectal prolapse based on clinical criteria.

PURPOSE: Reports of outcome after surgery for rectal prolapse predominantly relate to single operative procedures. A single surgical operation is not appropriate for all patients with rectal prolapse. We describe a selective policy based on clinical criteria. METHODS: Patients were offered surgery according to the following broad clinical protocol. Those who were unfit for abdominal surgery had a perineal operation. The remainder had a suture abdominal rectopexy. A sigmoid resection was added for patients in whom incontinence was not a predominant symptom. RESULTS: Surgery was performed in 159 patients. Of these, 57 had a perineal operation, 65 had fixation rectopexy, and 37 had resection rectopexy. There were no in-hospital deaths, and major complications occurred in five patients (3.5 percent). Minimum follow-up was 3 years. Of the 143 patients with long-term follow-up, recurrence occurred in 7 (5 percent). Constipation increased from 41 to 43 percent (59-61/143) and incontinence decreased from 43 to 19 percent (61 to 27/143). CONCLUSIONS: A selective policy has improved outcome compared with reports of a single operation. Future studies might consider an objective method of selecting the type of operation for rectal prolapse.

Abdomen↗
PubMed2004

Surgery for occult rectal prolapse.

OBJECTIVE: An 'occult' rectal prolapse may be diagnosed during investigation of altered bowel habit. It has been suggested that the outcome of surgery for these patients may be associated with results that are inferior to those achieved in patients with overt rectal prolapse. This study compares the results of surgery for 'occult' and overt rectal prolapse in terms of mortality, morbidity and change in bowel habit. PATIENTS AND METHODS: A retrospective review was undertaken of consecutive patients undergoing surgery for rectal prolapse during the decade 1988-98. Resection rectopexy was the treatment of choice except in patients with faecal incontinence who underwent sutured rectopexy. Those patients who were unfit for an abdominal operation were offered a perineal procedure. Outcome measures were mortality, morbidity, prolapse recurrence, constipation and faecal incontinence. Data were retrieved from case note review, clinical assessment, telephone consultation or postal questionnaire. RESULTS: Rectal prolapse surgery was undertaken in 69 patients with an overt prolapse and 74 patients with an 'occult' prolapse. Patients in the 'occult' prolapse group were significantly younger than those with overt prolapse (P = 0.0002). There were significantly more perineal procedures in the overt prolapse group compared with the 'occult' prolapse group (54% vs 5%, P = 0.0001). There were no deaths within 28 days of surgery. Major surgical complications occurred in 5 patients (3.5%). Seven patients (10%) experienced recurrent prolapse. Rectal prolapse surgery reduced the incidence of St. Mark's grade 4 faecal incontinence from 38% to 19% in the overt prolapse group (P = 0.023) and from 49% to 22% in the 'occult' prolapse group (P < 0.001). Following surgery the incidence of constipation increased in the 'occult' group from 39% to 50% but decreased in the overt prolapse group from 42% to 35%. CONCLUSIONS: Surgery for an 'occult' rectal prolapse is unlikely to benefit patients whose principle symptom is constipation. Approximately half of those patients whose 'occult' rectal prolapse is associated with faecal incontinence will have their bowel habit improved by prolapse surgery.

Adolescent↗
PubMed2004

The value of an elastic tissue stain in detecting venous invasion in colorectal cancer.

BACKGROUND: Venous invasion by tumour is an independent prognostic indicator of both prognosis and risk of development of distant metastases in colorectal carcinoma. The use of special stains to aid its detection in pathology specimens is not currently universally recommended. AIMS: To determine whether an elastica stain significantly increases the incidence of detection of vascular invasion compared with routinely stained sections. METHODS: Serial sections from the 75 cases of colorectal carcinoma were stained by haematoxylin and eosin (H&E) only and elastica counterstained with H&E. The incidence of both intramural and extramural venous invasion was recorded and compared with that seen when the tumours were originally reported. RESULTS: Extramural venous invasion had been noted in 14 of the pathology reports and was seen in 18 cases when only the H&E sections were viewed in the study. It was present in 32 cases when elastica stained sections were analysed. Intramural venous invasion was seen in eight cases on H&E sections and 30 cases on elastica stained sections. CONCLUSION: The use of elastica stained serial sections to detect venous invasion in tumours should be recommended in guidelines for the reporting of colorectal carcinomas.

Blood Vessels↗
PubMed2003

Risk of dysplasia in the columnar cuff after stapled restorative proctocolectomy.

BACKGROUND: Stapled restorative proctocolectomy (SRP) for ulcerative colitis retains a 'cuff' of columnar epithelium, which carries a risk of undergoing malignant change. The risk of neoplastic transformation was studied in a series of patients who underwent SRP for ulcerative colitis. METHODS: One hundred and thirty-five patients who underwent SRP for ulcerative colitis between 1988 and 1998 were followed up by cuff surveillance biopsy. The median follow-up was 56 (range 12-145) months and the median time since diagnosis of ulcerative colitis was 8.8 (range 2-32) years. RESULTS: The cuff biopsies showed no dysplasia or carcinoma. The accuracy of obtaining cuff mucosa in the biopsy was 65 per cent. Chronic inflammation was present in 94 per cent of cuff biopsies. CONCLUSION: This study shows no evidence of either dysplasia or carcinoma in the columnar cuff mucosa, up to 12 years after pouch formation. This suggests that cuff surveillance in the first decade after SRP, in the absence of dysplasia or carcinoma in the original colectomy specimen, may be unnecessary. Regular cuff surveillance biopsies after SRP should continue for patients with high-grade dysplasia or carcinoma in the original resection specimen.

Cell Transformation, Neoplastic↗
PubMed2002

The vestibulo-ocular reflex and velocity storage in spinocerebellar ataxia 8.

The autosomal dominant spinocerebellar ataxias (SCAs) are a group of neurodegenerative diseases characterized by progressive instability of posture and gait, incoordination, ocular motor dysfunction, and dysarthria due to degeneration of cerebellar and brainstem neurons. Among the more than 20 genetically distinct subtypes, SCA8 is one of several wherein clinical observations indicate that cerebellar dysfunction is primary, and there is little evidence for other CNS involvement. The aim of the present work was to study the decay of the horizontal vestibulo-ocular reflex (VOR) after a short period of constant acceleration to understand the pathophysiology of the VOR due to cerebellar Purkinje cell degeneration in SCA8. The VOR was recorded in patients with genetically defined SCA8 during rotation in the dark. Moderate to severely affected patients had a qualitatively intact VOR, but there were quantitative differences in the gain and dynamics compared to normal controls. During angular velocity ramp rotations, there was a reversal in the direction of the VOR that was more pronounced in SCA8 compared to controls. Modeling studies indicate that there are significant changes in the velocity storage network, including abnormal feedback of an eye position signal into the network that contributes to this reversal. These and other results will help to identify features that are diagnostic for SCA subtypes and provide new information about selective vulnerability of neurons controlling vestibular reflexes.

Cerebellum↗
PubMed2001

Transtympanic tetrodotoxin alters the VOR and Fos labeling in the vestibular complex.

The sodium channel blocker tetrodotoxin (TTX) is an effective tool for blockade of action potentials. Unilateral transtympanic administration of 3 mM TTX produced behavioral symptoms similar to those following unilateral peripheral vestibular ablation. Complete resolution of visible symptoms occurred between 48 and 72 h post-TTX. Eye-coil recordings indicated a spontaneous nystagmus and a decrease in the VOR in TTX-treated animals. Neuronal activity in the central vestibular complex (VC), as monitored with Fos immunocytochemistry, revealed an asymmetric pattern of Fos labeling in the medial, inferior and superior vestibular nuclei and the prepositus hypoglossal nucleus. Although the spatio-temporal pattern of Fos labeling was consistent and reproducible at each time-point, changes were noted among time-points. Transient blockade with TTX may be useful for studying the central vestibular response to recurrent or episodic vestibular disruption in the intact system.

Animals↗
PubMed2001

System for robotically assisted percutaneous procedures with computed tomography guidance.

We present the prototype of an image-guided robotic system for accurate and consistent placement of percutaneous needles in soft-tissue targets under CT guidance inside the gantry of a CT scanner. The couch-mounted system consists of a seven-degrees-of-freedom passive mounting arm, a remote center-of-motion robot, and a motorized needle-insertion device. Single-image-based coregistration of the robot and image space is achieved by stereotactic localization using a miniature version of the BRW head frame built into the radiolucent needle driver. The surgeon plans and controls the intervention in the scanner room on a desktop computer that receives DICOM images from the scanner. The system does not need calibration, employs pure image-based registration, and does not utilize any vendor-specific hardware or software features. In the open air, where there is no needle-tissue interaction, we systematically achieved an accuracy better than 1 mm in hitting targets at 5-8 cm from the fulcrum point. In the phantom, the orientation accuracy was 0.6 degrees, and the distance between the needle tip and the target was 1.04 mm. Experiments indicated that this robotic system is suitable for a variety of percutaneous clinical applications.

Biopsy, Needle↗
PubMed2001

The relationship of pudendal nerve terminal motor latency to squeeze pressure in patients with idiopathic fecal incontinence.

PURPOSE: With the advent of transanal ultrasonography it has been possible to identify those incontinent patients without sphincter defects. The majority of these patients are now thought to have neurogenic fecal incontinence secondary to pudendal neuropathy. They have been found to have reduced anal sphincter pressures and increased pudendal nerve terminal motor latencies. The aim of this study was to determine whether in those incontinent patients who do not have a sphincter defect, prolonged pudendal nerve terminal motor latency correlates with anal manometry, in particular maximum squeeze pressure. METHODS: Sixty-six incontinent patients were studied with transanal ultrasonography, anorectal manometry, and pudendal nerve terminal motor latency. Twenty-seven continent controls had anorectal manometry and pudendal nerve terminal motor latency measured. RESULTS: Maximum resting pressure and maximum squeeze pressure were significantly lower in the group of incontinent patients with bilateral prolonged pudendal nerve terminal motor latency (median maximum resting pressure = 26.5 mmHg; median maximum squeeze pressure = 60 mmHg) when compared with incontinent patients with normal bilateral pudendal nerve terminal motor latencies (median maximum resting pressure = 46 mmHg; median maximum squeeze pressure = 79 mmHg; maximum resting pressure P = 0.004; and maximum squeeze pressure P = 0.04). In incontinent patients with no sphincter defects no correlation between pudendal nerve terminal motor latency and maximum squeeze pressure was found (r = -0.109, P = 0.48) and maximum squeeze pressure did not correlate with bilateral or unilateral prolonged pudendal nerve terminal motor latency (r = -0.148, P = 0.56 and r = 0.355, P = 0.19 respectively). CONCLUSIONS: In patients with idiopathic fecal incontinence damage to the pelvic floor is more complex than damage to the pudendal nerve alone. Although increased pudendal nerve terminal motor latency may indicate that neuropathy is present, in patients with neuropathic fecal incontinence, pudendal nerve terminal motor latency does not correlate with maximum squeeze pressure. Normal pudendal nerve terminal motor latency does not exclude weakness of the pelvic floor.

Adult↗
PubMed2001

Strategy for the surgical management of patients with idiopathic megarectum and megacolon.

BACKGROUND: Several surgical procedures have been used to treat idiopathic megabowel. A structured approach to the surgical management of megarectum/colon is reported. METHODS: Twenty-eight consecutive patients with megabowel referred for surgery were reviewed. All patients had conservative treatment for 6 months. Those failing to improve underwent full-thickness biopsy of the anorectal junction, anorectal physiology studies, colonic transit studies and evacuation proctography. Surgery involved excision of the abnormal large bowel and formation of an anastomosis (coloanal or ileoanal) using 'normal' bowel identified either by a defunctioning stoma or colonic motility studies. RESULTS: Eight patients responded to conservative management. Two patients were lost to follow-up and one died from unrelated causes. Two of the 17 patients who underwent full-thickness biopsy were cured by the procedure. Anorectal physiology, colonic transit and evacuation studies did not aid selection of the surgical procedure performed in 15 patients: proctectomy and coloanal anastomosis (six), restorative proctocolectomy (three), panproctocolectomy (one) and defunctioning stoma (five). At a median follow-up of 3.6 years, 13 of 15 evaluable patients had a satisfactory outcome. CONCLUSION: Approximately 40 per cent of patients with megabowel referred for surgery responded to conservative treatment. The remaining patients may be treated successfully by surgery. The use of either a 'diagnostic' defunctioning stoma or colonic motility studies may aid in the choice of surgical procedure.

Adolescent↗
PubMed2001

Factors that predict complications after construction of a stoma: a retrospective study.

OBJECTIVE: To find out our incidence of complications of stoma surgery and identify variables that predict outcome. DESIGN: Retrospective study. SETTING: Teaching hospital, Scotland. SUBJECTS: All 121 patients who had 126 stomas constructed during 1996. INTERVENTIONS: Follow up until the end of 1999. MAIN OUTCOME MEASURES: Morbidity and mortality. RESULTS: There were 64 men and 57 women, median age 58 years, range 16-83. Forty-three stomas were constructed for malignancy (34%). Forty-two stomas were raised during emergency operations (33%). Colorectal surgeons created 96 stomas (76%). Sixty-one of 92 potentially reversible stomas were closed (66%). Two patients died (2%) perioperatively. Overall stoma-related morbidity was 68% (n = 85). The rate of major stoma-related complications was 26% (n = 33). Nine major complications resulted in a reoperation rate of 7%. On univariate analysis, age, American Society of Anesthesiologists (ASA) grade, and surgeon's speciality were significant predictive variables of major stomal complications (p < or = 0.002, 0.02, and 0.05 respectively). Multivariate analysis showed that the age of the patient was the only factor that independently influenced the outcome of stoma surgery (p < or = 0.001). CONCLUSIONS: Optimising the perioperative health status of the patients, particularly the elderly, may reduce morbidity. The results also support specialist surgical care of patients undergoing stomal surgery.

Adolescent↗
PubMed2001

Graphical human insulin time-activity profiles using standardized definitions.

The purpose of this study was to (1) develop consistent definitions to report time-activity profiles of insulin formulations, (2) determine human insulin time-activity profiles based on all available pharmacokinetic studies of biosynthetic human insulin rDNA(E. coli) (Humulin), and (3) create graphs that accurately and usefully represent human insulin time-activity profiles (TAPs). Standard definitions of onset, peak, duration, and time of 50% maximal activity were developed for human insulin. Results from all pharmacokinetic and pharmacodynamic studies available on human insulin from searches of both published literature and unpublished work were analyzed by these standard methods. Data obtained using these definitions were used to construct diagrams of the time-activity relationships for each formulation. Sixty-three insulin tests utilizing a variety of methodologies and data analysis techniques were located. Time-activity curves generated by application of standardized definitions varied depending on methodology, and on whether glucose, insulin and/or glucose infusion rates were used as the measure of insulin activity. A method of standard analysis is required for evaluating insulin pharmacokinetic studies due to the wide variation in design of these studies. Graphic representation of ranges obtained by standard analysis of onset, peak, duration, and 50% maximal activity increase the information transmitted when compared to currently used tables of time-activity data. The time of 50% maximal activity during increasing and decreasing phases may be a better marker of clinically significant activity than the classically defined parameters of onset and duration.

Blood Glucose↗
PubMed2000

Respiratory toxicity of fabric softener emissions.

To determine whether there is any biological basis for complaints that fabric softener emissions can cause acute adverse effects in certain individuals, screening tests were performed in which groups of mice were exposed to the emissions of 5 commercial fabric softener products (antistatic pads used in laundry dryers) for 90 min. Pneumotachographs and a computerized version of ASTM test method E-981 were used to measure acute changes in several respiratory cycle parameters, especially the pause after inspiration, the pause after expiration, and the midexpiratory airflow velocity. From these changes, sensory irritation (SI), pulmonary irritation (PI), and airflow limitation (AFL) of differing intensities were measured with each of the five brands tested. At the peak effect, SI ranged from 21 to 58% of the breaths, PI ranged from 4 to 23% of the breaths, and AFL ranged from 6 to 32% of the breaths. After three exposures, histopathology revealed mild inflammation of interalveolar septae of the lungs. Gas chromatography/ mass spectroscopy (GC/MS) analysis of the emissions of one pad identified several known irritants (isopropylbenzene, styrene, trimethylbenzene, phenol, and thymol). Laundry that had been dried with one the fabric softener pads emitted sufficient chemicals to elicit SI in 49% of breaths at the peak effect Placing one fabric softener pad in a small room overnight resulted in an atmosphere that caused marked SI (61% of breaths). These results demonstrate that some commercial fabric softeners emit mixtures of chemicals that can cause SI, PI, and reduce midexpiratory airflow velocity in normal mice. The results provide a toxicological basis to explain some of the human complaints of adverse reactions to fabric softener emissions.

Air Pollutants↗
PubMed2000

Focal hepatic ablation using interstitial photon radiation energy.

BACKGROUND: Intratumoral ablative therapy is being used increasingly for the treatment of primary and secondary hepatic malignancies. The interstitial point-source photon radiosurgery system (PRS) is a novel ablative technique that uses radiation therapy similar in dosimetry to interstitial brachytherapy. STUDY DESIGN: To determine the feasibility, toxicity, and local tissue destructive capabilities of the PRS in the liver, preliminary studies in a nontumor-bearing canine model were examined. A 6-month survival study was conducted. Each animal received three radiation treatments, in the right, central, and left hepatic regions. Three low-dose treatments were delivered to each of six animals (group A), generating a 2.0-cm-diameter radiated sphere with a dose of 20 Gy at the lesion edge. Three high-dose treatments were delivered to each of six animals (group B), generating a 3.0-cm-diameter radiated sphere with 20 Gy at the lesion edge. RESULTS: The treatment reproducibly generated sharply demarcated hepatic ablative lesions proportional to the administered dose. Mean lesion diameter at 1 month was 1.6+/-0.2 cm in group A and 3.4+/-1.0 cm in group B. Lesion size was independent of intrahepatic location, including near vascular structures. PRS therapy, when applied to portal structures, resulted in hilar damage. Hilar damage appeared to be associated with arteriolar thrombosis and bile duct injury. Treatment of regions adjacent to large hepatic veins and the IVC was not associated with vessel thrombosis or stricture. CONCLUSIONS: PRS ablation is a generally well-tolerated method that results in consistent, well-demarcated, symmetric lesions of complete necrosis with minimal adjacent parenchymal injury. Application of such an approach for the treatment of liver tumors is promising.

Animals↗