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Biomedical subjects

J Corson

Publications and source records attributed to J Corson.

At least 19 recordsLinked to original sources
PubMed2002

Palliative stenting of malignant large bowel obstruction.

OBJECTIVE: Untreated malignant large bowel obstruction is rapidly fatal. Short-term palliation of symptoms can be achieved by formation of a stoma in those patients for whom resection surgery is inappropriate. In the final months of life, a stoma represents a significant burden for both patients and carers. Palliative endoluminal stenting may therefore be an attractive alternative option for this poor prognosis group. In this paper, we examine our experience of palliative endoluminal colonic stenting. PATIENTS: Twenty patients, 11 males and 9 females of median age 81 years were referred for stenting. All had left sided colonic cancers. Ten patients had confirmed metastases on presentation, four had fixed rectal cancers and the remainder had severe comorbidity limiting surgical options. Stents were placed endoscopically using a radiologically controlled 'stent over wire' technique. RESULTS: Stenting successfully relieved the obstruction in 18 of the 20 patients attempted. In one patient the stricture could not be negotiated and the procedure was abandoned. Eleven patients have died of their disease, their median duration of palliation was 50 days (3-152 days). The rest of the patients continue in follow-up and have had 80 days median palliation (14-257 days). One stent-related complication has been observed in a patient who suffered anal pain due to fracture and migration of part of a stent into the low rectum. This complication occurred after 250 days and the distal stent fragment was removed with further symptom relief. CONCLUSION: Carefully selected patients benefit from colonic endoluminal stenting with relief of obstructive symptoms. They may be spared the potential problems associated with palliative stoma formation.

Journal Article↗
PubMed2000

Low-frequency crossover of the fractional power-Law conductivity in SrRuO3

We combine the results of terahertz time-domain spectroscopy with far-infrared transmission and reflectivity to obtain the conductivity of SrRuO3 over an unprecedented continuous range in frequency, allowing us to characterize the approach to zero frequency as a function of temperature. We show that the conductivity follows a simple phenomenological form, with an analytic structure fundamentally different from that predicted by the standard theory of metals.

Journal Article↗
PubMed2000

Nodal quasiparticle lifetime in the superconducting state of Bi(2)Sr(2)CaCu(2)O(8+delta)

We have measured the complex conductivity sigma of a Bi(2)Sr(2)CaCu(2)O(8+delta) thin film between 0.2 and 0.8 THz. We find sigma in the superconducting state to be well described as the sum of contributions from quasiparticles, condensate, and order parameter fluctuations which draw 30% of the spectral weight from the condensate. An analysis based on this decomposition yields a quasiparticle scattering rate on the order of k(B)T/Planck's over 2pi for temperatures below T(c).

Journal Article↗
PubMed2000

Parasite-secreted products regulate the host response to larval Taenia crassiceps.

Parasite-induced immunosuppression is believed to play a significant role in the pathology of cysticercosis, a disease caused by the larval stage of cestode parasites. The biochemical basis for immunoregulation by Taenia crassiceps in experimental cysicercosis is unknown. In order to determine whether or not excretory/secretory (E/S) products from the parasite have the ability to regulate host immune function, the activity of these products was examined. Excretory/secretory products from larvae early in the infection were found to suppress T cell proliferative responses in vitro as well as the production of IFN-gamma and IL-4. In contrast, E/S products secreted from larvae harvested late in infection were not suppressive. Electrophoretic analysis of E/S products revealed both qualitative and quantitative differences in the pattern of proteins produced by larvae taken from an early infection versus those taken from a chronic infection. The viability of parasites taken from an early infection was greatly reduced compared to those taken from chronically infected mice, suggesting a change in the nature of the host immune response to the parasite during the course of the infection. The proliferative activity and cytokine profiles of host immune cells were examined. Both mesenteric lymph node cells and peritoneal exudate cells were found to produce high levels of both IFN-gamma and IL-4, consistent with the high levels of these cytokines in sera of chronically infected animals. Chronic infection with Taenia crassiceps therefore is characterized by high levels of production of both Th1 and Th2 cytokines by host cells.

Age Factors↗
PubMed2000

The separation of benign and malignant mesothelial proliferations.

The separation of benign from malignant mesothelial proliferations has emerged as a major problem in the pathology of the serosal membranes. For both epithelial and spindle cell mesothelial processes, true stromal invasion is the most accurate indicator of malignancy, but stromal invasion is often difficult to assess, especially in small biopsies. In the pleural cavity, deep penetration of a thickened and fibrotic pleura or penetration of mesothelial cells into the fat of the chest wall are good indicators of malignancy; however, superficial entrapment of mesothelial cells and glands by organizing effusions is common in benign reactions and needs to be distinguished from invasion. In the peritoneal cavity, invasion of fat or of organ walls is again the most reliable indicator of malignancy, but entrapment of benign cells in organizing granulation tissue or between fat lobules is frequent and confusing. Proliferations confined to the pleural or peritoneal space, particularly linear arrays of atypical mesothelial cells on the free surface, should not be called malignant in the absence of unequivocal invasion. Cytologic atypia is often not helpful in separating benign from malignant reactions, because benign processes are commonly atypical and mesotheliomas are often deceptively monotonous. Densely packed mesothelial cells within the pleural space are frequent in benign reactions, but densely packed mesothelial cells within the stroma favor a diagnosis of malignancy. Organizing effusions (fibrous pleurisy) typically show zonation with high cellularity and cytologic atypia toward the pleural space and increasing fibrosis with decreasing cellularity and lesser atypia toward the chest wall, whereas sarcomatous (including desmoplastic) mesotheliomas do not demonstrate this type of zonation. Elongated capillaries perpendicular to the pleural surface are seen in organizing effusions but are not a feature of sarcomatous mesotheliomas. The combination of a paucicellular storiform pattern, plus invasion of the stroma (including fat and adjacent tissues), or bland necrosis, overtly sarcomatous foci, or distant metastases, is required for the diagnosis of desmoplastic mesothelioma. Necrosis is usually a sign of malignancy but is occasionally seen in benign mesothelial reactions. Keratin staining is useful in indicating the distribution of mesothelial cells, and particularly in demonstrating penetration of mesothelial cells into the stroma or adjacent structures, but is of no help in separating benign and malignant proliferations because both are keratin-positive. Although both p53 and EMA staining have been proposed as markers of mesothelial malignancy, in our experience they are not helpful for the individual case.

Diagnosis, Differential↗
PubMed1997

Renal hilar Doppler analysis is of value in the management of patients with renovascular disease.

BACKGROUND: An increasing interest in the role of Doppler ultrasound and duplex scan in screening for renovascular hypertension has recently been noted. We conducted this study to define the role of renal hilar Doppler ultrasound (RHDU) in evaluating renal artery stenosis and its value in the postoperative follow-up after renal revascularization. METHODS: One hundred and fourteen patients are included in this study with a mean age of 63.7 (11 to 89) years. Seventy-two patients underwent renal revascularization. The most frequent revascularization procedure was renal artery bypass in 82%. The RHDU results were compared with 130 angiograms done within 1 month of the RHDU study. The Doppler velocity signal in a segmental artery in the renal parenchyma was recorded, and the waveform was analyzed. An acceleration index (AI) less than 3.78 KHz/sec/MHz and an acceleration time (AT) greater than 0.1 seconds were used to indicate the presence of a significant renal artery stenosis. RESULTS: The overall technical success rate of all RHDU studies was 93.5%. The AI value was higher in the group of patients with normal renal arteries than those with a stenosis (4.7 +/- 1.4 KHz/sec/MHz versus 1.23 +/- 1.13 kHz/sec/MHz, respectively, P <0.0001), and the AT was lower in the former group compared with the latter (0.052 +/- 0.011 sec versus 0.122 +/- 0.069 sec, P <0.0001). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for AI were 89%, 92%, 85%, 94%, and 92%, respectively; and for AT were 62.5%, 97.5%, 91%, 86.5%, and 87% respectively. There was a significantly high agreement between the AI and AT results and those of arteriography (Kappa of 0.82 and 0.66, respectively, P < 0.0001). There were 10.6% kidneys with multiple renal arteries by arteriography. In these kidneys the accuracy was lower for both AI and AT and the agreement with arteriography was nonsignificant. In the postoperative period the accuracy of RHDU was 86% for AI and 95% for AT. CONCLUSIONS: Renal hilar Doppler ultrasound has a high accuracy and agreement with arteriography in the diagnosis of renal artery stenosis. Its value is limited by the presence of multiple renal arteries, renal artery occlusion, and high incidence of postoperative false-positive results. It can be useful as a noninvasive screening test for patients suspected of having renal artery stenosis and for surveillance following renal revascularization.

Adolescent↗
PubMed1997

Internal iliac revascularization during aortic aneurysm replacement: a review and description of a useful technique.

The coexistence of infrarenal aortic aneurysm and internal iliac artery aneurysm may represent a management problem with regard to preservation of the pelvic blood supply. In this article, we review the methods available for maintaining the pelvic blood flow and describe a useful technique that we have successfully utilized in seven patients to preserve the hypogastric artery blood flow.

Anastomosis, Surgical↗
PubMed1996

Reliability of longitudinal ultrasonographic measurements of carotid intimal-medial thicknesses. Asymptomatic Carotid Artery Progression Study Research Group.

BACKGROUND AND PURPOSE: Serial ultrasonic B-mode measurements of intimal-medial thickness (IMT) of the carotid artery are commonly used as surrogates for describing atherosclerosis progression. This report describes the longitudinal reliability of IMT measurement during a multicenter clinical trial, quantifies the error attributable to differences among readers, and discusses how studies can be efficiently designed. METHODS: Serial B-mode measurements of carotid IMT from the 3-year Asymptomatic Carotid Artery Progression Study (ACAPS; formerly Asymptomatic Carotid Artery Plaque Study) were used to estimate the contributions to longitudinal measurement error of systematic reader effects, nonvisualization, and nonsystematic error and to describe the distribution of "true" progression rates that underlie the observed data. Variance components were estimated from random-effects models fitted to outcome measures formed by averaging IMTs from different sets of carotid artery walls. These were used to contrast the relative efficiency of study designs. RESULTS: Of the total variance of measured IMT, 11% was attributable to systematic differences among readers. Nonvisualization contributed less than 7%. Thus, the predominant source of error was unaccounted for (ie, random error or "noise," which in our analyses included any drift, nonlinearity, and sonographer differences). For studies with measurement protocols similar to ACAPS, follow-up times of 2 years or more are desirable for describing the mean progression rates of cohorts, and of 6 years or more for categorizing progression within individuals. In 3-year studies, sample sizes as low as 237 provide 90% statistical power for detecting risk factors that have correlations with IMT progression of .50 or greater. CONCLUSIONS: The ACAPS measurement protocol provided highly reliable serial IMT data. Moderate-sized multicenter studies using B-mode outcomes are feasible.

Adult↗
PubMed1992

Meningococcal disease in Wales: clinical features, outcome and public health management.

In Wales, in 1988, 119 patients with meningococcal disease were identified, so giving a crude annual incidence of 4.2 patients per 100,000 population. The combined classical clinical features of fever, vomiting, neck stiffness, headache and purpuric rash were identified in only 9% of patients. Fever and vomiting were the commonest symptoms, both being present in 60% of patients. A rash was noted in 77% of patients but neck stiffness in only 39%. Rash was more common in children, headache and photophobia in adults. A total of 13 patients died, the fatality rare increasing with age from 3% in infants to 20% in older teenagers and adults. Only 15% of 75 patients admitted to hospital by general practitioners were known to have received intravenous or intramuscular penicillin before admission as recommended by the Chief Medical Officers of the Health Departments in the U.K. Only 24% of patients received rifampicin to clear nasopharyngeal carriage before or at discharge from hospital. Altogether, 375 household contacts of patients were identified. At least 84% of them received chemoprophylaxis.

Acute Disease↗
PubMed1992

Cutaneous perianal recurrence of cancer after anterior resection using the EEA stapling device.

We present a case of cutaneous recurrence from an adenocarcinoma of the rectum, which was diagnosed 7 months after anterior resection of the primary tumour had been performed using the EEA stapling device to fashion the anastomosis. We propose that the recurrence was caused by the seeding of exfoliated tumour cells into an area of perianal skin which was abraded during the introduction of the stapling gun.

Adenocarcinoma↗
PubMed1988

Malignant mesothelioma: prognostic variables in a registry of 180 patients, the Dana-Farber Cancer Institute and Brigham and Women's Hospital experience over two decades, 1965-1985.

All mesothelioma patients identified by a computer search of pathologic diagnoses at the Dana-Farber Cancer Institute (DFCI) between 1965 and 1985 were the subjects of this analysis. A total of 180 patients were identified, 136 with pleural and 37 with peritoneal mesothelioma. There were five pericardial and two testicular primaries. Of the two decades included in the study, later patients were significantly older, with a more advanced disease stage, and a lower performance status than those accrued early in the study. Factors at diagnosis associated with a significantly prolonged survival for all patients with mesothelioma included a 0 to 1 performance status, absence of chest pain, age less than 50 years, and epithelial histology. Factors at diagnosis associated with prolonged survival for the subset of patients with pleural mesothelioma included epithelial histology, 0 to 1 performance status, the absence of chest pain, an interval of greater than 6 months from onset of symptoms, and treatment with chemotherapy and pleuropneumonectomy. This last result must be interpreted with caution, since this was not a randomized study.

Boston↗
PubMed1988

Diagnostic value of the history and examination in giant cell arteritis: a clinical pathological study of 81 temporal artery biopsies.

To determine the value of the history and examination in predicting a temporal artery biopsy result, 81 temporal artery biopsies between 1974-1980 were studied. Each biopsy was scored blindly and independently by 2 pathologists and correlated with clinical data and the indications for biopsy at the time of the biopsy. Thirteen biopsies had giant cells and were considered positive, 8 had mononuclear inflammatory cells in the wall (7 cases) or healed arteritis (1 case) and were considered probable, and 60 were negative. In patients with an elevated sedimentation rate, the presence of a sign (tenderness or abnormal temporal artery), or a symptom (visual change or headache) predicted 18 of 21 (86%) positive-probable biopsies, but misclassified 32 of 60 negative biopsies. Attempts to derive a clinical decision rule with improved specificity resulted in unacceptably low sensitivity (missing 5 of 21 positive-probable biopsies). A minimum 5-year followup showed that those patients treated with steroids had a 6-fold increase in fractures and a 4-fold increase in cataracts.

Aged↗
PubMed1988

Combined modality treatment of peritoneal mesotheliomas.

Five patients with peritoneal mesothelioma were treated with a multimodality approach consisting of debulking surgery, ip chemotherapy, and whole-abdomen irradiation. Chemotherapy included cisplatin and doxorubicin; radiation was given by an open-field technique. Three patients remain disease free at 46, 60, and 61 months after diagnosis. This treatment approach may serve as a model for common tumors characterized by abdominal carcinomatosis.

Adult↗
PubMed1987

Long-term survival in peritoneal mesothelioma. The role of radiotherapy and combined modality treatment.

Ten patients with peritoneal mesothelioma were treated at the Joint Center for Radiation Therapy between 1968 and 1985. Six of the ten patients remained free of disease at 19+ to 78+ months after diagnosis. The six patients received sequential surgical debulking, combination chemotherapy, and whole-abdomen irradiation. Four patients not treated with this multimodality approach died with disease. This approach may have an impact on the natural course of peritoneal mesothelioma, and warrants further study.

Adult↗
PubMed1986

Tailored media can enhance the success of smoking cessation clinics.

Smokers recruited through the medical outpatient clinics of two similar Veterans Hospitals over two successive years participated in a smoking cessation study which randomized them between a group assigned to behavior modification clinics and a group receiving a packet of smoking cessation material in the mail. Following the second year's clinics at the site of one of the two hospitals, an intensive media campaign, based on the content of the behavior modification program, was targeted at the study population over commercial television and radio. The six-month abstinence rate for clinic participants measured by self-report, serum thiocyanate and exhaled air carbon monoxide was 36.8% in the group assigned to clinic followed by media, 20.2% in the group assigned to clinic alone, and 10.6% in the group receiving materials in the mail. The difference in cessation rates between the clinic participants who were and those who were not exposed to the media following their clinics was significant at the 0.05 significance level (chi 2 = 3.9, 1 d.f.). Logistic analysis confirmed the benefit of the media campaign.

Adult↗