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C D Johnson

Publications and source records attributed to C D Johnson.

At least 55 records · Page 3Linked to original sources
PubMed2001

Roles of norepinephrine and ATP in sympathetically evoked vasoconstriction in rat tail and hindlimb in vivo.

In anesthetized rats, we characterized the contributions of norepinephrine (NE) and ATP to changes in tail and hindlimb (femoral) vascular resistances (TVR and FVR, respectively) evoked by three patterns of sympathetic stimulation: 1) couplets (2 impulses at 20 Hz), 2) short trains (20 impulses at 20 Hz), and 3) a natural irregular pattern previously recorded from a sympathetic fiber innervating the rat tail artery. All stimuli evoked greater changes in TVR than FVR. Judging from the effects of the alpha-adrenoceptor antagonist phentolamine, the purinergic receptor antagonist suramin, or alpha,beta-methylene ATP (which desensitizes P2X receptors), we propose that NE has a major role in the constriction evoked by the couplet, as well as by the short train and by the low- and high-frequency components of the natural pattern, but that considerable synergy occurred between the actions of ATP and NE. This contrasts with previous in vitro studies that indicated that ATP dominates vascular responses evoked by sympathetic stimulation with a few impulses at low frequency and that NE dominates responses to longer trains or at high frequencies.

Adenosine Triphosphate↗
PubMed2001

Preoperative biliary drainage before resection in obstructive jaundice.

BACKGROUND: Surgery for patients with malignant obstructive jaundice carries high morbidity and mortality rates. Preoperative biliary drainage (PBD) has been used in an attempt to improve the outcome in these patients. AIM: To review the evidence in the literature on whether PBD improves postoperative morbidity and mortality in obstructive jaundice patients. MEHOD: Using Medline a literature search was performed for papers published in English from January 1980 to October 2000, using the text words 'obstructive jaundice', 'preoperative', 'drainage' and 'stent'. All retrieved papers which reported experimental or clinical observations relevant to the study aim were carefully analysed and the findings are summarised in this review. RESULTS AND CONCLUSION: There is no evidence in the literature to support the view that routine PBD improves postoperative morbidity and mortality in patients with obstructive jaundice undergoing resection. PBD has its own complications that cancel out its benefits. However, PBD could be beneficial in patients presenting with sepsis, coagulation abnormalities or malnutrition.

Adult↗
PubMed2001

Body composition, physiological function and psychological changes in patients with predicted severe acute pancreatitis.

BACKGROUND: Serious sepsis and major blunt trauma have adverse effects on body composition, physiological function and psychological state. The effect of severe acute pancreatitis on these groups of variables has not yet been reported. METHODS: We have studied the effect of predicted severe acute pancreatitis (admission APACHE II score > or = 6) on body fat and mid arm muscle circumference (assessed by dual-energy X-ray absorptiometry and anthropometry), respiratory function (measured by spirometry and vitalography), voluntary muscle function (measured by hand dynamometry) and psychological state (measured by use of the hospital anxiety and depression score and visual analogue scale for fatigue) on admission, and three and seven days thereafter. RESULTS: The median APACHE II score of the 15 patients (7 men) in this study was 10 (6-13). The patients showed significant improvement in respiratory function (FEV1 1.3, 1.6, 2.3 litres/s, p < 0.01; FVC 1.5, 2.0, 2.9 litres, p < 0.01; PEFR 304, 372, 409 litres/min, p = 0.01 but no change in voluntary muscle function (210, 205, 213 N, p = 0.41) over the 7-day study period. Psychological state improved in terms of fatigue (2.4, 4.2, 7.0, p < 0.01) and depression (6, 9, 4, p = 0.12) but not in anxiety (8, 6, 7, p = 0.07). Body fat measured by DEXA (17.3 kg on admission, 16.7 kg on day 7, p = 0.13) and the mid upper arm muscle circumference (262, 248, 251 mm, p = 0.10) did not change implying that energy and nitrogen balance over the 7-day study period was achieved. CONCLUSION: Predicted severe acute pancreatitis has an adverse effect on respiratory function and psychological state similar to that observed in serious sepsis. Improvement in these variables is apparent over 7 days of effective treatment. Further research is indicated to examine the effect of nutritional support on these variables.

APACHE↗
PubMed2001

Body composition, muscle function and psychological changes in patients undergoing operation for hepatic or pancreatic disease.

BACKGROUND: There is currently a dearth of data with respect to changes in body composition, physiological function and pSychological state in patients undergoing operative treatment for pancreatic or hepatic disease although marked changes in these variables have been reported in colorectal surgical patients. METHODS: In 36 patients (37 operations) we have studied the effect of a pancreatic or hepatic operation (with and without nutritional support) on body fat and body protein (assessed by Dual energy X-ray absorptiometry (DEXA) and anthropometry), respiratory function (measured by spirometry and vitalography), voluntary muscle function (measured by hand dynamometry) and psychological state (measured by use of the hospital anxiety and depression score and visual analogue scale for fatigue) over a 1-week period postoperatively. RESULTS: On the 3rd postoperative day there were significant changes in: grip strength 307 (135-499) to 249 (85-461) N; FEV1 2.28 (0.48-3.98) to 1.02 (0-2.42) litres/min; FVC 2.90 (0.75-5.02) to 1.28 (0.22-3.31) litres; anxiety score 7 (0-17) to 6 (1-20); depression score 3 (0-10) to 5 (0-20), and fatigue 3.9 (0.4-10) to 6.8 (1.0-9.7). These persisted on day 7 by which time mid-arm circumference and total body fat (by DEXA) had fallen from 30.1 (21.1-45.0) to 29.5 (20.2-43.2) cm, and 20.7 (5.8-53.7) to 20.4 (6.6-53.5) kg, respectively. CONCLUSION: We conclude that operative treatment for pancreatic or hepatic disease has an adverse effect on body composition, physiological function and psychological state.

Adipose Tissue↗
PubMed2001

Imaging of neuroendocrine tumors of the pancreas.

BACKGROUND: Neuroendocrine tumors of the pancreas are uncommon neoplasms of the pancreas that can occur sporadically or in association with various syndromes such as multiple endocrine neoplasia type 1 (MEN I). Patients can present with a specific clinical syndrome related to biochemically functioning tumors or with nonspecific symptoms related to mass effect or metastases. The size, function, consistency, and malignant behavior of neuroendocrine tumors are integrally related. Imaging has a major role in the preoperative localization of the primary tumor and detection of metastases. Several techniques are available including ultrasound, endoscopic ultrasound, computed tomography (CT), MR, somatostatin receptor scintigraphy, angiography, and arterial stimulation with venous sampling; each with unique advantages and limitations. The reported performance for these techniques vary widely, and as a result, recommended imaging algorithms are controversial. Recent technical advances in ultrasound, CT, and MRI have occurred that may improve the sensitivity of some of the techniques. Further improvements are likely in the future. In this chapter we will review imaging techniques used to study the pancreas as it relates to the detection of neuroendocrine tumors, imaging findings of these tumors using various imaging modalities, and the advantages, limitations and results obtained with each technique.

Diagnosis, Differential↗
PubMed2001

Growth hormone in neural tissues of the chick embryo.

Growth hormone (GH) gene expression predominantly occurs in the pituitary gland, although it also occurs in many extrapituitary sites, including the brain. The cellular location and ontogeny of neural GH production is, however, largely unknown. This has therefore been determined during chick embryogenesis. In chicks, the brain develops from the neural tube at embryonic day (ED) 3. At this age, the divisions of the brain (the telencephalon, diencephalon, mesencephalon, metencephalon and myelencephalon) have intense GH immunoreactivity (GH-IR) (detected by two polyclonal antibodies and a monoclonal antibody for chicken GH). The otic and optic vesicles were also strongly GH immunoreactive, as were the Vth (semi-lunar), VIIth (facial), VIIIth (acoustic) and IXth (glossopharyngeal) nerve ganglia. This GH-IR was specific for GH and was lost when the antibodies were preabsorbed with recombinant chicken GH. The widespread distribution of GH-IR in the neural tissues of ED 3 embryos was mirrored by the distribution of GH receptor (GHR) immunoreactivity, detected by an antibody raised against the chicken GHR. In ED 6/ED 7 embryos, the neural retina of the eye and the epithelial and lens fiber cells were intensely stained for GH-IR, as was Rathke's pouch and the wall of the diencephalon. In contrast, only a few scattered cells were immunoreactive in the surrounding mesoderm. At ED 14, the GH-IR in the brain was restricted to specific tissues and cells. For instance, immunoreactive cells were present in the molecular and pyramidal layers of the cerebral cortex, in the gray matter of the cerebellum, in the choroid plexus, and in the walls of the ventricles. In summary, GH- and GHR-like proteins are abundant in neural tissues of the chick during the first third of incubation, becoming discretely localized to specific tissues and cells during later incubation. The localization of GH and GHR in these tissues, prior to the ontogeny of plasma GH, suggests autocrine or paracrine roles for GH during early embryogenesis.

Animals↗
PubMed2001

Effect of vascular occlusion on radiofrequency ablation of the liver: results in a porcine model.

OBJECTIVE: This study determined the effect of vascular occlusion on radiofrequency lesion shape, volume, and temperature in a porcine liver model. SUBJECTS AND METHODS: Radiofrequency lesions (n = 33) were created in the livers of six domestic pigs in vivo using a multiprong radiofrequency electrode. Lesions were randomly assigned to one of four vascular occlusion groups: portal vein, hepatic artery, Pringle maneuver (both hepatic artery and portal vein), or no occlusion. Radiofrequency parameters were time, 7 min; power, 50 W; and target temperature, 100 degrees C. Temperatures were measured 5, 10, and 15 mm from the electrode. After the animals were sacrificed, the lesions were excised. Lesion volume, diameter, and shape; maximum temperature; and time exposed to lethal temperatures (42-60 degrees C) were determined. RESULTS: Lesion volume was greatest with the Pringle maneuver lesions (12.6 +/- 4.8 cm(3)), followed by occlusion of the portal vein (8.6 +/- 3.8 cm(3)), occlusion of the hepatic artery (7.6 +/- 2.9 cm(3)), and no occlusion (4.3 +/- 1.0 cm(3)) (p < 0.05). Maximum lesion diameter was similar with the Pringle maneuver (3.3 +/- 0.3 cm), the portal vein (3.3 +/- 0.2 cm), and the hepatic artery (3.2 +/- 0.2 cm) groups compared with no occlusion (2.6 +/- 1.0 cm) (p < 0.05). Minimum lesion diameter ranged from 2.9 cm for Pringle maneuver lesions to 1.0 cm for lesions with no occlusion (p < 0.05). Vascular occlusion increased the time tissue was exposed to lethal temperatures (> 42-60 degrees C) and created more spherical lesions than no occlusion. CONCLUSION: Vascular occlusion combined with radiofrequency ablation increases the volume of necrosis, creates a more spherical lesion, and increases the time tissue is exposed to lethal temperatures when compared with radiofrequency alone. Most of this vascular occlusion effect could be accomplished with hepatic artery occlusion alone.

Animals↗
PubMed2001

Carcinoid tumors of the stomach: a clinical and radiographic study.

OBJECTIVE: Our purpose is to describe associated and coexistent diseases of gastric carcinoid tumors, the unique biologic behavior of these tumors, the appearance of these tumors on fluoroscopic and CT images, and the radiologic management of these neoplasms. CONCLUSION: First, multiple gastric carcinoid tumors are associated with enterochromaffin-like cell hyperplasia, chronic atrophic gastritis, and pernicious anemia and have a low risk of malignancy. Second, solitary gastric carcinoid tumors, or gastric carcinoid tumors associated with multiple endocrine neoplasia-type I (MEN-I) and Zollinger-Ellison syndrome, have a higher potential for metastatic disease. Third, the radiologic appearance and management of these tumors depend on the clinical background of the patient.

Aged↗
PubMed2000

Safety and efficacy of mangafodipir trisodium (MnDPDP) injection for hepatic MRI in adults: results of the U.S. multicenter phase III clinical trials (safety).

The short-term safety of mangafodipir trisodium (MnDPDP) injection was studied in 546 adults with known or suspected focal liver lesions. An initial contrast-enhanced computed tomography examination was followed by unenhanced magnetic resonance imaging (MRI), injection of MnDPDP (5 micromol/kg), and enhanced MRI. Adverse events were reported for 23% of the patients; most were mild to moderate in intensity, did not require treatment, and were not drug related. The most commonly reported adverse events were nausea (7%) and headache (4%). The incidence of serious adverse events was low (nine events in six patients) and not drug related. Injection-associated discomfort was reported for 69% of the patients, and the most commonly reported discomforts included heat (49%) and flushing (33%). Changes in laboratory values and vital signs were generally transient, were not clinically significant, and did not require treatment. There were no clinically significant short-term risks from exposure to MnDPDP.

Abdominal Pain↗
PubMed2000

Effect of 1-(gamma)linolenyl-3-eicosapentaenoyl propane diol on the growth of human pancreatic carcinoma in vitro and in vivo.

Essential fatty acids such as (gamma)linolenic (GLA) and eicosapentaenoic (EPA) acids have been proposed as anticancer drugs. The aim of this study was to test the effect of a lipid emulsion containing both GLA and EPA in a novel chemical formulation of 1-(gamma)linolenyl-3-eicosapentaenoyl propane diol on the growth of human pancreatic carcinoma in vitro and in nude mice. This compound had a dose-dependent growth-inhibitory effect on human pancreatic cancer cell lines MIA PaCa-2 and Panc-1 in vitro. The concentration necessary for 50% growth inhibition was 25 micromol/l for MIA PaCa-2 and 68 micromol/l for Panc-1 (95% CI 20-29 and 59-77 micromol/l respectively). Nude mice bearing subcutaneous pancreatic tumours produced with the MIA PaCa-2 cell line were treated with the maximum tolerated dose (6.75 mg GLA and 7.3 mg EPA per g of body weight) administered over 10 days by daily intravenous (i.v.) bolus injections. No antitumour effect or major alteration in tumour lipid fatty acid composition was seen in comparison with control animals. Concurrent treatment with parenteral iron (iron saccharate, 5 microg/gram body weight daily) did not make a significant difference. Further improvements in fatty acid delivery mechanisms are necessary before they can become useful anticancer agents.

Animals↗
PubMed2000

Magnetic resonance cholangiography in patients with biliary disease: its role in primary sclerosing cholangitis.

BACKGROUND/AIM: Magnetic resonance cholangiography (MRC) is a non-invasive diagnostic procedure whose role in the management of patients with primary sclerosing cholangitis (PSC) is unclear. The aim of this study was to determine the usefulness of MRC in the evaluation of the biliary tree in patients with suspected biliary disease, and in particular, PSC. METHODS: MRC and invasive cholangiography (ERCP or PTC) were both performed in 73 patients, (33 male, 40 female, mean age 56 years) with clinical and/or biochemical evidence of cholestasis. Images were interpreted by two radiologists unaware of the results of other studies. RESULTS: Forty-two patients (58%) had benign biliary disease, including 23 patients (32%) with PSC; 9 patients (12%) had malignant biliary disease; and 22 patients (30%) had a normal biliary tree. Diagnostic quality images were obtained in 73/73 (100%) of MRC, and in 70/73 (96%) of invasive cholangiography (68 ERCP's, 2 PTC's) procedures. Using ERCP/PTC findings as the reference standard, MRC had an accuracy greater than 90% in the diagnosis of normal bile ducts, biliary dilatation, biliary obstruction, bile duct stones, and PSC. Using the final diagnosis, MRC had an overall diagnostic accuracy of 90% in the detection of biliary disease compared to 97% for invasive cholangiography. Additional diagnostic/therapeutic interventions were performed during ERCP in 73% of patients with PSC and in 43% of patients without PSC (p=0.02). CONCLUSIONS: MRC has excellent diagnostic accuracy in the presence of biliary disease. Because of its noninvasive nature, MRC may have advantages over invasive cholangiography when diagnosis is the major goal of the procedure.

Adult↗
PubMed2000

A prospective audit against national standards of the presentation and management of acute pancreatitis in the South of England.

BACKGROUND: The incidence of acute pancreatitis shows regional variations in the UK. AIMS: To document the incidence and presentation of acute pancreatitis in hospitals in Wessex, and to audit the process and outcome of management of patients against the UK guidelines. METHODS: A prospective survey was carried out of all patients with acute pancreatitis in a one year period, in eight geographically adjacent acute hospitals in the Wessex region. RESULTS: 186 patients with acute pancreatitis were identified, an incidence of 152 per million in the adult population. Aetiology was: gallstones 33%, alcohol 20%, idiopathic 32%, other 15%. There were 60 severe cases with 17 deaths. Age and APACHE-II score had significant relations to outcome, but delay to admission, serum amylase level, aetiology, and sex did not. The mortality rate (9.1%) was within the audit standard of 10%. Some management goals were not met: in mild cases, only one third of patients with gallstone pancreatitis had definitive treatment within four weeks. In severe cases, there was poor use of objective severity stratification (19%), low admission rates to a high dependency unit or intensive care unit (67%), and only 33% of patients had computed tomography. Only seven of 17 patients with severe gallstone pancreatitis had an urgent endoscopic retrograde cholangiopancreatography. CONCLUSIONS: The incidence of clinically diagnosed acute pancreatitis in England continues to rise. Current management of acute pancreatitis is suboptimal when compared with evidence based UK guidelines but the mortality rate was within the guideline standard.

Acute Disease↗
PubMed2000

Incidental extracolonic findings at CT colonography.

PURPOSE: To determine the frequency of extracolonic findings at computed tomographic (CT) colonography and the effect of these findings on subsequent patient treatment and cost. MATERIALS AND METHODS: Conventional transverse CT colonographic scans in 264 consecutive patients were evaluated independently by two radiologists. Extracolonic findings were classified as having high, moderate, or low clinical importance. The effect of CT findings on patient treatment was assessed with chart review. The cost of additional examinations was calculated by using 1999 Medicare reimbursements. RESULTS: Thirty (11%) patients had highly important extracolonic findings, which resulted in further examinations in 18 (7%) patients, including ultrasonography in 10, CT in 13, and intravenous pyelography in one. Six patients underwent surgery because of incidentally discovered CT colonographic findings. Two patients with findings of moderate or low importance underwent additional imaging. A total of $7,324 was required for work-up for extracolonic findings (mean of an additional $28 per examination). Three extracolonic malignancies were overlooked at CT colonography. CONCLUSION: Additional work-up of extracolonic CT colonographic findings was relatively infrequent but was often worthwhile when performed for lesions classified as highly important. The evaluation of extracolonic structures at CT colonography has definite limitations with regard to solid organs but can help detect serious disease without substantially increasing the cost per patient.

Abdomen↗
PubMed2000

CT colonography: the next colon screening examination?

Computed tomographic (CT) colonography is a new-generation technique for detecting colorectal neoplasms by using volumetric CT data combined with specialized imaging software. Patient examinations require full colonic preparation, insufflation, and data acquisition with the patient in the supine and prone positions. Current CT technology allows a single image of the colon to be acquired in as little as 20 seconds with a minimum of patient discomfort. Specialized computer software for interpretation usually combines transverse, multiplanar reformation, and three-dimensional endoluminal images for the optimal visualization of the colon and rectum. As of the time this article was written, CT colonography was competitive as a full structural colonic examination for the detection of polyps and cancer. To the authors' knowledge, no study results have yet been reported in a screening population. The unique capabilities of CT colonography include the display of the proximal colon that is inaccessible at colonoscopy because of obstructing colonic lesions or because of incomplete endoscopic examinations and the assessment of extracolonic abdominal and pelvic organs. This abdominopelvic survey potential provides radiologists with an opportunity to discover other potentially life-threatening, asymptomatic conditions. Further technologic developments and validation studies are in progress. CT colonography is an exciting and promising technique with an enormous potential for colorectal screening in the future.

Colon↗
PubMed2000

Optimization of CT colonography technique: prospective trial in 180 patients.

PURPOSE: To assess the added benefits of prone positioning in addition to supine positioning and oral iodinated contrast medium for help in the detection of colonic polyps at computed tomographic (CT) colonography. MATERIALS AND METHODS: CT colonography was performed in prone and supine positions in 180 patients with polyps or risk factors for colonic neoplasia. Patients were randomly assigned to receive a standard bowel preparation or a standard preparation plus oral iodinated contrast medium. One radiologist interpreted supine images alone, and another analyzed supine and prone images. All patients subsequently underwent colonoscopy. RESULTS: At colonoscopy, 121 large (> or =1-cm-diameter) polyps and 142 smaller (0.5-0.9-cm) polyps were identified. Prone positioning resulted in increased sensitivity for identification of patients with large (> or =1-cm) polyps (increase from 70% to 85%, P: =.004) and of patients with polyps 0.5 cm or larger (increase from 75% to 88%, P: <.005), with no change in specificity. Use of oral contrast medium did not significantly improve polyp detection even in the subset of patients in whom colonic fluid attenuation was markedly increased. CONCLUSION: Acquisition and review of supine and prone CT colonographic images significantly improves the ability to identify patients with polyps 0.5 cm in diameter or larger. Administration of oral iodinated contrast medium does not significantly improve polyp detection.

Colon↗