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Biomedical subjects

C Dick

Publications and source records attributed to C Dick.

At least 19 recordsLinked to original sources
PubMed1998

Accumulation of amphotericin B in human macrophages enhances activity against Aspergillus fumigatus conidia: quantification of conidial kill at the single-cell level.

A cytofluorometric assay that allowed assessment of damage to phagocytosed Aspergillus fumigatus conidia at the single-cell level was developed. After ingestion by monocyte-derived macrophages (MDMs), conidia were reisolated by treatment of the cells with streptolysin O, a pore-forming toxin with lytic properties on mammalian cells but not on fungi. The counts obtained by staining of damaged conidia with propidium iodide and quantification by cytofluorometry correlated with colony counts. By the use of this method, we demonstrate that MDMs differentiated in vitro by low-dose granulocyte-macrophage colony-stimulating factor and gamma interferon have only a limited capacity to damage Aspergillus conidia in vitro. The killing rate 12 h after phagocytosis was found to be only 10 to 15%. However, intracellular loading of the phagocytes with amphotericin B (AmB) dose dependently enhanced the anticonidial activity. Preincubation of macrophages with only 1 microg of AmB per ml resulted in an uptake of 18 fg of AmB/cell, leading to killing rates of 50 to 60%. The experimental protocol provides a new tool for the rapid quantification of anticonidial activity against A. fumigatus in vitro. Intracellular accumulation of AmB may represent an important factor underlying the efficacy of this antifungal drug in the prophylaxis and treatment of Aspergillus infections.

Amphotericin B↗
PubMed1997

Refractory hypoxemia due to intrapulmonary shunting associated with bronchioloalveolar carcinoma.

Bronchioloalveolar carcinoma caused severe refractory hypoxemia due to intrapulmonary shunting in a patient. Preoperative evaluation by occlusion of the pulmonary lobar artery supplying the tumor showed normalization of the arterial oxygen saturation. Resection of the involved lobe corrected the intrapulmonary shunting, and the patient required no further supplemental oxygen. However, with recurrence of the tumor over the next 6 months the patient became progressively more hypoxemic and died.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1995

Alkalosis and hypomagnesaemia: unwanted effects of a low-calcium CAPD solution.

We studied 43 CAPD patients for 4 months during the change from a high-calcium dialysis fluid (Baxter PD1) to a low-calcium fluid (Baxter PD4), which also contained low magnesium (0.25 mmol/l) and high lactate concentrations (40 mmol/l). Serum calcium fell significantly as did the incidence of hypercalcaemia, whilst the proportion of patients taking calcium-containing phosphate binders increased. There was a non-significant increase in serum i-PTH levels but the proportion with i-PTH > 150 pg/ml (normal range 10-65 pg/ml) increased significantly. There was a significant fall in serum magnesium level and seven patients developed hypomagnesaemia. Serum bicarbonate increased significantly and progressively and 17 patients were alkalotic at 4 months, five severely (bicarbonate 35-40 mmol/l). One patient developed recurrent episodes of painful subcutaneous and periarticular calcification, which may have been related to the alkalosis. Initial serum bicarbonate levels correlated significantly with dialysis adequacy assessed by daily Kt/V (r = 0.458, P = 0.002). The relationship to adequacy was abolished during the period of use of the high-lactate dialysis fluid. Use of low-magnesium CAPD fluids must be supported by regular monitoring of serum magnesium levels. The high lactate concentration in such fluids may not be appropriate and is potentially hazardous when individualization of dialysis dose demands the use of relatively high exchange volumes. Low serum bicarbonate levels in CAPD patients reflect inadequate dialysis, which use of these fluids serves to mask.

Adult↗
PubMed1994

Emergency department two-dimensional echocardiography in the diagnosis of nontraumatic cardiac rupture.

Myocardial rupture is a catastrophic complication of acute myocardial infarction that usually results in sudden death. If diagnosed quickly, patients with myocardial rupture may be salvaged. This report describes the application of emergency department two-dimensional echocardiography in the diagnosis of six cases of myocardial rupture over two years. Each demonstrated a characteristic hemopericardium on limited single-window examination. These included four patients who met institutional guidelines for thrombolytic therapy. Three patients survived surgical repair, with two long-term survivors.

Aged↗
PubMed1993

Differentiating systolic from diastolic heart failure: pathophysiologic and therapeutic considerations.

PURPOSE: To compare and contrast the pathophysiology and therapy of heart failure with normal and abnormal systolic ventricular function. METHODS: Review of basic pathophysiologic mechanisms, clinical data, and therapeutic trials. CONCLUSIONS: The clinical features of heart failure may be similar regardless of whether ventricular function is normal or abnormal. However, the pathophysiologic mechanisms leading to heart failure with normal ventricular function differ considerably from those producing heart failure with abnormal systolic function. The key problems in heart failure with abnormal systolic function involve impaired contractility, neuroendocrine activation, increased intracardiac volume and pressure, and enhanced sensitivity to change in afterload. With normal systolic function, the key problem is an abnormal diastolic pressure/volume relationship, which may be due to a variety of active and passive processes affecting diastole. Assessing left ventricular systolic function is crucial before initiating therapy in a patient with heart failure, since treatment for systolic dysfunction may be ineffective or even counterproductive if symptoms are due to abnormal diastolic properties with preserved systolic function.

Clinical Trials as Topic↗
PubMed1990

Safety and efficacy of a new transpulmonary ultrasound contrast agent: initial multicenter clinical results.

Myocardial contrast echocardiography has been found to be a safe and useful technique for evaluating relative changes in myocardial perfusion and delineating areas at risk. Although earlier contrast agents required direct delivery into the coronary arteries or aortic root, a new echocardiographic contrast agent, sonicated albumin microspheres (Albunex), has been found to cross the pulmonary circulation in experimental models. To determine the safety and preliminary efficacy of intravenous injections of Albunex in humans, 71 patients at three independent medical institutions underwent two-dimensional echocardiographic examination before, during and after the administration of three intravenous doses of Albunex, ranging from 0.01 to 0.12 ml/kg body weight. All patients provided a complete history and underwent physical and neurologic examination and laboratory and electrocardiographic evaluation before the injections; all evaluations (except for the history) were repeated at 2 h and 3 days after the injections of Albunex. The efficacy of the injections was qualitatively assessed by two independent blinded observers using a grading system of 0 to +3, with 0 indicating an absence of contrast effect and +3 indicating full opacification of the cavities examined. All injections were well tolerated and no serious side effects were noted in any of the patients. Irrespective of dose group, a cavity opacification greater than or equal to +2 was seen in the right ventricle in 212 (88%) of 240 injections and in the left ventricle in 151 (63%) of 240 injections as judged by the independent observers. The degree of ventricular cavity opacification appeared to be dose and concentration related.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Contrast echocardiography: a method to visualize changes in regional myocardial perfusion in the dog model for CABG surgery.

The ability of contrast echocardiography to assess regional myocardial perfusion during cardiopulmonary bypass in a dog model for coronary artery bypass surgery was evaluated. Sonicated Renograffin-76 microbubbles (meglumin diatrigoate and sodium diatrigoate) were injected into an aortic root proximal to an aortic occlusion clamp root while dogs were on cardiopulmonary bypass, with the heart arrested in diastole. Echocardiographic contrast-enhanced regions of myocardial perfusion were easily visualized. Differences in contrast-enhanced myocardial regions depended on coronary artery occlusion or patency. The contrast-enhanced images of myocardial perfusion showed that, for a given myocardial segment of the supplying vessel, the presence or absence of contrast effect reliably predicted vessel occlusion or patency (P less than .01). In the future contrast echocardiography may allow the direct assessment of regional myocardial perfusion in the operating room.

Animals↗
PubMed1988

Contrast echocardiography during coronary arteriography in humans: perfusion and anatomic studies.

In humans, the physiologic relation between myocardial blood flow and epicardial coronary artery anatomy remains poorly defined. With the recent development of sonicated microbubble contrast agents, it is now possible to use contrast echocardiography to assess myocardial perfusion and to correlate blood flow with angiographically identified coronary artery anatomy. The purpose of the current study was to determine myocardial perfusion patterns in patients without significant coronary artery disease. The results may be used as a reference to analyze myocardial blood flow in patients with coronary artery disease. Sonicated meglumine sodium diatrizoate solution (Renografin-76), which contains microbubbles measuring 4.5 +/- 2.8 micrograms in diameter by laser analysis, was used as the echocardiographic contrast agent during elective coronary arterriography in 14 patients without significant coronary artery disease. Patients received intracoronary injections of 1.5 to 2 ml of sonicated Renografin-76 without complications. Perfusion characteristics were studied by visual assessment of the two-dimensional echocardiographic images obtained after individual injections. In patients found to be free of significant coronary artery disease by arteriography, the left coronary system always supplied the anteroseptal, anterior, anterolateral and posterior regions of the left ventricle at the mid-papillary, cross-sectional level. The right coronary artery system perfused the inferior and inferoseptal regions in 89% of the patients identified with a right dominant system. The anterolateral papillary muscle was perfused from the left coronary system in all cases. The posteromedial papillary muscle was perfused from the left coronary system in 58% of the patients and from the right system in 42% of the patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗