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Biomedical subjects

C D Johnson

Publications and source records attributed to C D Johnson.

At least 199 records · Page 11Linked to original sources

Timing of intervention in acute pancreatitis.

This review examines the appropriate timing of intervention in acute pancreatitis. In gallstone pancreatitis, it is now clear that cholecystectomy during the primary admission carries no greater risk of complications than delayed cholecystectomy and enables earlier recovery to normal activity. This course of action pre-empts a second, possibly fatal attack of acute pancreatitis. Cholecystectomy should be done after the acute phase has settled, before discharge from hospital. Patients with gallstones should now be offered endoscopic sphincterotomy within 48 hours of admission. This approach is safe, and reduces the risk of complications. When complications develop, early necrosectomy is only indicated if conservative measures fail. Delayed (> 10 days) necrosectomy is appropriate if there is evidence of sepsis, or clinical failure to improve. Pancreatic pseudocysts can often be managed expectantly; a high proportion will resolve spontaneously. After a delay of 12 weeks, persistent cysts require evaluation by endoscopic pancreatography, which gives crucial information in the choice between percutaneous or surgical drainage of the pseudocyst. A patient with pancreatitis is usually treated under the care of a surgeon, who has traditionally taken the decision on the timing of any intervention, and has performed such intervention at open operation. Recently, the development of alternative techniques has enabled the surgeon to call on the skills of his colleagues in endoscopy and interventional radiology. However, the availability of these alternatives to surgery should not affect the timing of intervention unless it can be clearly shown that such a change in timing combined with the minimally invasive technique can improve the outcome for the patient. Intervention may be required to deal with gallstones in the gallbladder or in the bile duct, to deal with, or ideally prevent, the deleterious systemic effects of pancreatic and peripancreatic necrosis, or to drain a peripancreatic abscess. Peripancreatic fluid collections and pancreatic pseudocysts may also require either internal or external drainage to relieve symptoms or prevent complications.

Acute Disease↗

Phase-contrast cine MR angiography in chronic liver disease.

Thirty-one patients with portal venous hypertension underwent phase-contrast cine magnetic resonance (MR) angiography to validate the technique for assessment of main portal vein patency and blood flow direction. Correlative findings from Doppler ultrasonography, conventional angiography, and surgery were acquired in 30, 17, and 16 patients, respectively. Findings from MR angiography correlated well with those of the other methods for determining portal vein patency and flow direction. The main portal vein was patent in 29 patients and was thrombosed in two patients at MR angiography. With the use of a 40-mm slab projection acquisition that required 5 minutes, the splenic and superior mesenteric veins, as well as extensive varices (when present), were seen in the majority of cases. Phase-contrast cine MR angiography is an accurate method of rapidly assessing morphologic characteristics, patency, and flow direction of the portal venous system and thus is a useful method for evaluating the condition of patients with chronic liver disease.

Adult↗

Evaluation of portal venous hypertension with cine phase-contrast MR flow measurements: high association of hyperdynamic portal flow with variceal hemorrhage.

Thirty-two patients with portal venous hypertension and endoscopically proved esophageal varices who were being evaluated for possible liver transplantation were studied with cine phase-contrast magnetic resonance (MR) imaging. Flow measurements in the main portal vein were obtained and associated with the presence of variceal hemorrhage within 2 years before the MR examination. Low (hypodynamic) flow was present in 22 patients, while high (hyperdynamic) flow was present in 10 patients. The presence of variceal hemorrhage was significantly associated with a high portal venous flow rate (P = .001), high variceal grade (P = .030), and Child class A or B (P = .003); however, only portal venous flow (P = .006) and variceal grade (P = .044) were found to be associated with variceal hemorrhage in a multiple logistic regression analysis. The portal venous flow rate was significantly higher among patients with Child class A or B disease compared with those with class C disease (median, 24.6 vs 8.0 mL/min.kg; P = .004).

Adult↗

Positive bowel contrast agent for MR imaging of the abdomen: phase II and III clinical trials.

PURPOSE: To evaluate the efficacy and safety of two dose levels of an orally administered ferric ammonium citrate-based contrast agent for bowel enhancement on T1-weighted spin-echo magnetic resonance (MR) images in 222 patients with known or suspected abnormality of the upper abdomen. MATERIALS AND METHODS: Adverse reactions were graded for intensity, frequency, duration, and relationship to the contrast agent. Twelve unblinded readers compared enhanced with unenhanced images; all MR images were evaluated by two independent offsite radiologists in a blinded review. RESULTS: No statistically significant changes in mean vital signs or laboratory values were seen. Forty-eight of 220 patients (22%) reported minor side effects. The readers found increased intraluminal signal intensity and improved contrast enhancement of the gastrointestinal tract and distention and improved signal homogeneity in 101-107 cases (89%-98%) after ingestion; the blinded reviewers' findings were similar. CONCLUSION: The contrast agent provided new or additional radiologic information in 142 patients (64%), specific additional information in a detected abnormality in 46 of 142 patients (32%), and information that changed diagnosis, management, or surgical approach in 22 of 142 patients (15%).

Abdomen↗

Volumetric flow rates in the portal venous system: measurement with cine phase-contrast MR imaging.

OBJECTIVE: The purposes of this study were to (1) validate the accuracy of cine phase-contrast MR flow measurements within the portal vein, (2) develop a suitable protocol for using this method to measure volumetric flow rate in the portal venous system, and (3) use this protocol, with Doppler sonography as a reference, to measure portal venous flow in healthy volunteers and in patients with protal venous hypertension. SUBJECTS AND METHODS: Flow determinations were obtained in a model of fluid movement approximating blood-flow conditions in the portal venous system. A suitable protocol was based on consideration of the theoretical effects of (1) spatial resolution, (2) obliquity of the imaging plane to the direction of flow, and (3) signal-to-noise ratio of the signed quantitative velocity images (in three volunteers) on the accuracy and precision of flow measurements. This protocol was used to obtain cine phase-contrast MR images of the portal venous system in five volunteers and six patients. RESULTS: Values obtained with a flow phantom showed good accuracy of cine phase-contrast-measured vs actual volumetric flow rate (r = .995; p = .0001; MR rate = [0.94 x actual rate] + 65.6 ml/min; standard error of the y estimate = 67.3 ml/min). Velocity encoding and section thickness substantially influenced the signal-to-noise ratio of the velocity images, whereas flip angle and matrix size had only minimal effect. In volunteers and patients, portal volumetric flow rates determined by using MR images and Doppler sonography showed good correlation (r = .94; p = .0003). CONCLUSION: Our results indicate that cine phase-contrast MR imaging is a practical noninvasive method for measuring volumetric flow rates in the portal venous system.

Adult↗

Correlation of arterial and venous blood flow in the mesenteric system based on MR findings. 1993 ARRS Executive Council Award.

OBJECTIVE: The purpose of this study was to determine if a consistent relationship exists between (1) flow in the portal vein and superior mesenteric vein and (2) flow in the mesenteric arteries. SUBJECTS AND METHODS: Cine phase-contrast methods were used to determine volumetric flow in the celiac axis, superior mesenteric artery, portal vein, and superior mesenteric vein in 11 healthy volunteers. RESULTS: The mean (+/- SD) volumetric flow rates in the celiac axis, superior mesenteric artery, superior mesenteric vein, and portal vein were 9.9 +/- 3.2, 6.0 +/- 1.8, 5.7 +/- 2.0, and 13.7 +/- 1.8 ml/min per kilogram, respectively. A strong correlation was found between measured mesenteric arterial blood flow, defined as the sum of flow in the celiac axis and the superior mesenteric artery, and portal venous flow (r = .97, p = .00002). Good agreement was found between flow in the superior mesenteric artery and that in the superior mesenteric vein (r = .98; p = .00001; bias = 20 ml/min). CONCLUSION: There is a consistent relationship between MR measurements of flow in the portal or superior mesenteric vein and the measured flow in the arteries supplying those veins. Flow in the superior mesenteric vein is an accurate predictor of flow in the superior mesenteric artery.

Adult↗

Malignant lymphoma of the maxillary sinus.

Cancer of the paranasal sinuses and nasal cavity is an uncommon disease accounting for less than 0.2% of all malignancies. Lymphoma of the paranasal sinuses is a rare clinical entity representing less than 100 cases a year. In most cases, tumors arising in the paranasal sinuses are of the non-Hodgkin's variety. Most of these tumors are asymptomatic in the early stages and are diagnosed only after invasion of adjacent structures with local bone destruction. Computed tomography is essential for staging. The prognosis and treatment of lymphoma of the paranasal sinuses are based on the anatomic staging and histologic subtype. The prognosis is favorable for patients with localized disease. The authors describe a malignant lymphoma of the maxillary sinus in a 44-year-old man.

Adult↗

Plasma amylase estimation in recurrent abdominal pain in children.

In a prospective study of 50 children who were admitted on more than one occasion with undiagnosed abdominal pain, the serum amylase was found to be normal in every case. One case of acute pancreatitis was diagnosed in over 8000 admissions. Serum amylase estimation did not contribute to the management of children with recurrent abdominal pain, and acute pancreatitis is so rare that routine amylase estimations cannot be recommended in paediatric surgical practice.

Abdominal Pain↗

Invasive aspergillosis of the sphenoethmoidal sinuses in an immunocompetent host.

Fungal infections of the nose and paranasal sinuses are uncommon; Aspergillus is the most frequently isolated fungal pathogen. Invasive aspergillosis is commonly seen as an opportunistic infection in the immunocomprised, debilitated host. Whereas fulminant infection in the otherwise healthy patient is rare, in the immunocompetent host with persistent signs and symptoms of sinusitis despite appropriate medical management, aspergillosis should be considered. Treatment of paranasal sinus aspergillosis requires correction of immunologic deficits, if possible; aggressive surgical debridement to provide adequate drainage and aeration of the sinuses; and adjunctive antifungal chemotherapy. The authors present an unusual case of invasive aspergillosis of the paranasal sinuses in an immunocompetent host.

Adult↗

Intra-arterial thrombolysis should be the initial treatment of the acutely ischaemic lower limb.

We review and discuss the initial management of acute arterial occlusion. Thrombolytic therapy has been available for over 25 years but has failed to gain universal acceptance in the initial management of this condition. Support for the use of initial thrombolytic therapy in all patients is based on the following arguments. It may be difficult to distinguish clinically between an embolic or a thrombotic occlusion, and inappropriate surgery in the latter may have disastrous consequences. Therefore, arteriography should be performed in all patients. It is then easy to place a catheter for thrombolytic therapy. This therapy allows treatment of associated medical problems before definitive surgery, and it may enable a more accurate assessment of the obstruction and better planning of surgery after dissolution of some of the occluding thrombus. Recanalisation may make reconstructive surgery easier and, finally, the results with initial thrombolysis are better than with surgery alone. The case against the motion is that expeditious surgery is in the patient's best interest, particularly in embolus, and when there is ischaemic damage to the limb. Furthermore, the reports of thrombolysis currently available are uncontrolled and do not demonstrate convincingly that the results of thrombolytic therapy are superior to surgery alone.

Acute Disease↗

Surgical excision alone is adequate treatment for primary colorectal cancer.

This debate examines the arguments for and against the proposal that surgical excision alone is adequate treatment for primary colorectal cancer. The arguments in favour are that the results from curative surgery are excellent and that despite many trials of adjuvant chemotherapy, radiotherapy and immunotherapy, the proposed benefits remain unproven. Recent improvements in surgical technique, particularly for dissection of rectal tumours, have shown the way towards further improvement using surgery alone, and it is clear from a national survey that technical factors related to individual surgeons play a large part in determining recurrence rates. With optimum primary treatment, surgical excision alone is indeed adequate therapy. The arguments against this motion are that although a considerable number of patients do survive with surgery, the 5-year survival rate is poor when there is extensive local invasion or lymphatic metastases. Surgery starts therapy by reducing the tumour load, but other modalities are required to destroy the cells which might subsequently develop into metastases. Trial results with adjuvant therapy are encouraging, although many contain too few patients. We cannot be content with the results of treatment of Dukes' Stage B and C tumours; more trials are needed to determine the best treatment for these patients.

Antineoplastic Combined Chemotherapy Protocols↗

GABA-immunoreactive neurons in the nematode Ascaris.

gamma-Aminobutyric acid (GABA) immunoreactive neurons in the cephalic, somatic, and caudal regions of the Ascaris nervous system were visualized with serial section and whole-mount GABA immunocytochemistry. In the ventral and dorsal nerve cords, GABA-like immunoreactivity (GLIR) is localized to the neurites and cell bodies of identified inhibitory motor neurons and to two fibers, one in each cord, that arise from neurons in the nerve ring. GLIR is absent from identified excitatory motor neurons and from ventral cord interneurons. In neurons containing GLIR, immunoreactivity was present throughout the cell, which argues against an exclusive localization of GABA at conventional synapses. In whole mounts, ten GABA-immunoreactive neurons were present in the cephalic region. These include four nerve ring-associated cells (the RME-like cells), two bilaterally symmetrical pairs of lateral ganglia neurons (the amphid-GABA and deirid-GABA cells) and one bilaterally symmetrical pair of ventral ganglion cells (the VG-GABA cells). In sections, the RME-like cells and the VG-GABA cells were consistently stained through the cephalic region. However, anti-GABA staining of the lateral ganglia cells in sections was light, thus suggesting that they contain less GLIR than the other more intensely stained GABA-immunoreactive neurons. In the caudal region, a single GABA-immunoreactive neuron was present in the dorsal rectal ganglion. Our data suggest that these ten cephalic neurons, and a single dorsal rectal ganglion neuron, use GABA as a neurotransmitter.

Animals↗