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C Becker

Publications and source records attributed to C Becker.

At least 217 records · Page 12Linked to original sources
PubMed1998

[Significance of electron-beam tomography in the evaluation of the patency of aortocoronary bypasses].

PURPOSE: Electron beam tomography (EBT) permits acquisition of images with high spatial and temporal resolution. The value of EBT and other imaging modalities for the depiction of patent coronary artery bypass grafts (ACVB, IMA) are compared to coronary angiography and an overview of current results is given. MATERIAL AND METHODS: Graft patency can be evaluated with indirect methods stress, such as echocardiography, radionuclide ventriculography, myocardial scintigraphy, positron-emission tomography (PET) and direct imaging modalities, such as Doppler/2D echocardiography, EBT, spiral computed tomography (SCT) and magnetic resonance angiography (MRA). RESULTS: With indirect methods graft patency can be evaluated with sensitivity of 64-100% and specificity of 73-100%. EBT and SCT are equivalent in sensitivity (= 94%) in the assessment of open venous grafts and specificity is up to 100%, but EBT is superior in the diagnosis of patent IMA grafts (sensitivity 100% vs 89%). Visualization of high-grade venous bypass stenosis seems possible with EBT. MRA with gradient echo technique is highly accurate in the assessment of patent venous grafts (sensitivity 77-93%) but has limited value in the evaluation of IMAs (sensitivity = 53%). Promising are ultrafast 3D-MRA methods which permit high accuracy (sensitivity = 94-96%) in assessing venous and arterial grafts. DISCUSSION: Indirect imaging methods cannot differentiate between an occluded bypass, progression of coronary artery disease and myocardial infarction. EBT and SCT are equivalent in the diagnosis of open and occluded venous grafts, but EBT is superior in the assessment of patent IMA grafts. Visualization of high-grade venous bypass stenosis seems possible with EBT. MRA techniques, especially ultrafast 3D-MR methods, are highly accurate in the assessment of patent venous and arterial grafts but are still limited to scientific research.

Coronary Artery Bypass↗
PubMed1998

[Functional imaging of the heart with electron-beam computed tomography].

PURPOSE: Electron-beam computed tomography (EBCT) enables examinations with a very short acquisition time of 50 ms and thus permits cardiac imaging without motion artifacts. Utilizing eight detector rings simultaneous image acquisition in up to eight levels and complete imaging of the whole heart is possible. In studies, functional imaging with EBCT was compared to our angiocardiography, echocardiography, radionuclide, ventriculography and magnetic resonance tomography. MATERIALS AND METHODS: ECG-triggered long- and short-axis cine studies were performed with the Imatron C-150 Evolution, acquiring 160 and 156 images at 8 and 12 levels. After manual tracing of epicardial and endocardial borders, ventricular size, ejection fraction, wall-thickening and myocardial mass were calculated. RESULTS: A very high correlation between EBCT and direct determination of right and left ventricle (r = 0.98 and r = 0.99) was demonstrated. Compared to echocardiography, angiocardiography and radionuclide ventriculography, assessment of ventricular function was more precise and more reliable. DISCUSSION: EBCT allows the exact and reliable determination of left and right ventricular function. Also precise assessment of myocardial mass is possible. However, the high radiation exposure and diagnostic effort have to be considered.

Angiocardiography↗
PubMed1998

[Calculation of absolute cerebral blood volume and cerebral blood flow by means of electron-beam computed tomography (EBT) in acute ischemia].

The utility of electron beam computed tomography (EBT) to estimate cerebral blood volume (CBV) and cerebral blood flow (CBF) was evaluated. Eleven patients with suspected acute cerebral ischemia were investigated. The EBT was performed with an acquisition time of 50 ms per slice at eight parallel levels. To compare signal/noise and contrast/noise ratios the data from the EBT investigation were compared to a similar examination on a spiral CT. The signal/noise ratio with EBT was about 30%, the contrast/noise ratio 25% of that with spiral CT. The absolute values of CBV were 4.9 +/- 1.2 ml/100 g (EBT); CBF was 50.5 +/- 7.0 ml/100 g/min in normal contralateral brain tissue. In four patients with proven infarcts on follow-up, the ischemic areas had a CBV ranging from 1.7 to 3.8 ml/100 g, while CBF ranged from 9.4 to 24.5 ml/100 g/min. Using a bolus injection of contrast material, calculation of absolute CBV and CBF is feasible using EBT. Advantages of EBT are the absolute measurements possible and it's multislice capability. Disadvantages, however, are caused by the high image noise, limiting the demarcation of ischemic tissue.

Acute Disease↗
PubMed1998

The impact of vasoactive substances on intraosseous pressure and blood flow alterations in the femoral head: a study based on magnetic resonance imaging.

In beagle dogs, the alterations of intraosseous pressure and blood supply in the femoral head that result from the administration of vasoactive substances were examined, and the changes were documented by magnetic resonance imaging (MRI). Vasoactive substance were infused into the medial and lateral circumflex femoral arteries of 12 beagle dogs. All infusions were done under standardised conditions with simultaneous measurements of venous blood flow and intraosseous pressure distribution in the proximal femur. The drugs were infused in three cycles of 30 min each separated by 30 min recovery periods, followed by MRI examination at the end of each experiment. At an intraosseous pressure of 14.3 (+/- 4.2) mmHg in the femoral head epiphysis (I), 11.6 (+/- 2.7) mmHg in the greater trochanter (II) and 9.3 (+/- 3.2) mmHg in the femoral shaft (III), a baseline flow of 96.2 (+/- 18.8, n = 12) ml/min was measured in the femoral vein. After infusing bradykinin at a concentration of 10(-6) moles, which is commonly known to lead to cerebral and subcutaneous oedema formation by vessel dilatation, the intraosseous pressure increased to (I): 49.1 (+/- 6.2) mmHg, (II): 42.5 (+/- 5.8) mmHg and (III): 38.3 (+/- 7.1) mmHg in the three measured femoral areas (n = 3). After the bradykinin injection, femoral vein flow increased to a peak value of 238.4 (+/- 43.4) ml/min and then dropped to 62.3 (+/- 14.2) ml/min after discontinuation of the bradykinin infusion. In a second and third series of tests, hyperosmolar (20% NaCl) and hypo-osmolar (distilled water) solutions were applied, also resulting in increased but lower mean intraosseous pressure values (17.3 +/- 4.1 and 25.7 +/- 5.1 ml/min, respectively) in all regions. When administering bradykinin, MRI scans taken immediately after completion of the experiment showed substantial oedema in the femoral muscular system, but without any changes of osseous signals in T1- or short time inversion recovery (STIR)-weighted images, nor did any changes occur when solutions of 20% NaCl or distilled H2O were injected. The results of our experiments demonstrate that acute increases of intraosseous pressure do not cause MRI signal alterations. We therefore conclude that in addition to the described pressure increase, other intraosseous alterations must occur to lead to the detectable signal changes found among patients with diagnosed femoral head necrosis. Finally, the short time period between the rise in intraosseous pressure and performing a conventional MRI may be one reason for missing the development of an intraosseous oedema. On the other hand, conventional MRI might have additional disadvantages for detecting intraosseous fluid compared with a dynamic imaging modality.

Animals↗
PubMed1998

The distribution of cartilage thickness in the knee-joints of old-aged individuals -- measurement by A-mode ultrasound.

OBJECTIVE: To provide data on the normal distribution of cartilage thickness in the knee joints of old-aged individuals. DESIGN: The accuracy and reproducibility of cartilage thickness measurements were evaluated with A-mode ultrasound, and the cartilage thickness distribution was examined throughout both knee joints of nine individuals aged between 62 and 94 yr. BACKGROUND: Data on the variation of cartilage thickness in the joint surfaces are relevant for the design of computer models of diathrodial joints and for surgical and arthroscopic procedures, particularly the calculation of cartilage material properties from indentation tests. METHODS: A 12.5 MHz A-mode ultrasound transducer was used, and after determining the accuracy and reproducibility of the system in comparison with CT arthrography and anatomical sections, the cartilage thickness was measured throughout the knee at 256 coordinate points. RESULTS: A-mode ultrasound yields results consistent with established methods. The cartilage thickness is distributed regularly in the knee-joint of older individuals. However, the absolute values are considerably lower than those previously reported for younger people, the mean (and maximal) thickness being 2.0 mm (3.3 mm) in the patella, 1.9 mm (3.3 mm) in the femur, and 1.9 mm (3.5 mm) in the tibia. CONCLUSION: If the results of computer models or surgical strategies are to be applied to the demographically important group of older individuals, the typical distribution of articular cartilage thickness in this group should be taken into consideration.

Journal Article↗
PubMed1998

Hyperemesis in late pregnancy--should we think of cancer? A case report.

Gastric cancer is unusual during pregnancy. The diagnosis may be delayed because specific symptoms are similar to typical pregnancy associated complaints. Our therapeutic management with palliative chemotherapy and later gastrectomy differs from other known cases, where surgical resection has been the treatment of choice. Surgery appears to have no influence on the prognosis of gastric cancer patients with hepatic metastases.

Adult↗
PubMed1998

Second unrelated bone marrow transplantation without additional conditioning therapy after engraftment failure.

A 37-year-old female highly alloimmunized by multiple transfusions received a sex matched HLA-identical unrelated bone marrow transplant for hypoplastic MDS-RA with moderate myelofibrosis. Conditioning consisted of total body irradiation, cyclophosphamide and ATG, GVHD prophylaxis consisted of CsA, MTX and prednisolone. The CD34+ stem cell content of the first graft was relatively low due to an inadequate harvest. The patient appeared not to have engrafted by day 23 post-BMT. She therefore received a second sex mismatched HLA-identical unrelated bone marrow graft on day 25 after two days of 3.5 mg/kg methylprednisolone from a different donor. Over the ensuing days, the first marrow showed slow engraftment followed by engraftment of the second graft. The first graft was then rejected, as monitored by peripheral blood studies of chimerism. No signs of acute GVHD were observed. Despite successful trilineage engraftment and complete second donor chimerism, the patient died from disseminated toxoplasmosis encephalitis and pneumonia on day +104.

Adult↗
PubMed1998

Heterogeneous expression of the polysialyltransferases ST8Sia II and ST8Sia IV during postnatal rat brain development.

Polysialic acid on the neural cell adhesion molecule is developmentally regulated and has been implicated in the plasticity of cell-cell interactions. The sialyltransferases ST8Sia II and ST8Sia IV are able to catalyze the synthesis of polysialic acid. This study compares the expression of ST8Sia II and ST8Sia IV mRNA during postnatal rat brain development. Northern blot analysis indicated a substantial down-regulation of ST8Sia II from high expression at postnatal day 2 to almost undetectable levels at the age of 6 months. In contrast, the decline of ST8Sia IV content was moderate. In the mature brain, ST8Sia IV is the predominant polysialyltransferase. In situ hybridization of selected brain regions at postnatal days 2, 11, and 21 confirmed the decline of ST8Sia II level in isocortex, hippocampus, and cerebellum. ST8Sia II was not detectable at any time point in the subependymal layer and the layers of the olfactory bulb. Persistent ST8Sia IV expression was localized in the subependymal layer, the glomerular layer of the olfactory bulb, and the granule cell layer of the dentate gyrus and in some widely dispersed cells of the isocortex. The distinct expression patterns of ST8Sia II and ST8Sia IV suggest their differential regulation. As discussed with regard to the persistent polysialic acid expression, ST8Sia IV should receive particular attention in the mature brain.

Aging↗
PubMed1998

Role of NF-kappaB in immune and inflammatory responses in the gut.

NF-kappaB is a pleiotropic transcription factor with key functions in the intestinal immune system. NF-kappaB family members control transcriptional activity of various promoters of proinflammatory cytokines, cell surface receptors, transcription factors, and adhesion molecules that are involved in intestinal inflammation. The perpetuated activation of NF-kappaB in patients with active inflammatory bowel disease suggests that regulation of NF-kappaB activity is a very attractive target for therapeutic intervention. Such strategies include antioxidants, proteasome inhibitors, inhibition of NF-kappaB by adenoviral I kappaB alpha expression vectors, and antisense DNA targeting of NF-kappaB. These approaches will hopefully permit the design of new treatment strategies for chronic intestinal inflammation.

Animals↗
PubMed1998

Differential activation of CD8+ tumor-specific Tc1 and Tc2 cells by an IL-10-producing murine plasmacytoma.

The involvement of counteractive CD8+ T-cell subsets during tumor-specific immune responses was analyzed in a syngeneic murine plasmacytoma model. CD8+ Tc cells against the immunogenic IL-10-producing BALB/c plasmacytoma ADJ-PC-5 can be easily induced by immunization of BALB/c mice with X-irradiated ADJ-PC-5 tumor cells in vivo and in vitro. However, the failure of recipient mice to mount a protective Tc response against the tumor during early stages of a real or simulated tumor growth is not due to immunological ignorance, but depends on the induction of tumor-specific tolerance, involving a population of tumor-induced CD8+ T cells that are able to inhibit the generation of tumor-specific Tc cells in a primary ADJ-PC-5-specific MLTC, using IFN-gamma as a suppressive factor. Whereas most long-term cultivated CD8+ ADJ-PC-5-specific Tc lines produce type-1 cytokines on stimulation, at least two of them, which were derived from a primary MLTC, display a type-2 cytokine spectrum. Furthermore, the primary in vitro Tc response against ADJ-PC-5 cells shows characteristics of a Tc2 response. The Tc response is strictly depending on tumor-derived IL-10. CD8+ Tc cells that are induced in a primary MLTC do not produce IFN-gamma, and the tumor-specific Tc response is enhanced by IL-4 but suppressed by IFN-gamma or IL-12. In contrast, ADJ-PC-5-specific CD8+ Tc cells from immunized mice are IFN-gamma producing Tc1 cells. Since the primary in vitro Tc response against the tumor is suppressed even by the smallest numbers of irradiated ADJ-PC-5-specific Tc1 cells via IFN-gamma, these Tc1 cells behave similar to the suppressive CD8+ T cells that are induced during early stages of ADJ-PC-5 tumorigenesis.

Animals↗
PubMed1998

Preoperative 3D-reconstructions of ultrafast-CT images for the planning of minimally invasive direct coronary artery bypass operation (MIDCAB).

BACKGROUND: The direct left internal mammary artery (LIMA) bypass to the left anterior descending (LAD) without the use of extracorporal circulation through a small anterolateral thoracotomy has become established among the minimally invasive techniques in cardiac surgery. Technical difficulties may occur in patients with an enlarged left ventricle and subsequent lateral positioning of the LAD, a small LAD, or a small LIMA. We used electron beam tomography (EBT) for preoperative visualization of the topographical structures to seek out patients with potential technical difficulties. METHODS: Eighteen patients, mean age 62 +/- 13 years, were entered in this study; in all cases the indication for revascularization was a significant stenosis of the LAD. Preoperatively an ECG-triggered EBT was performed. Following the image acquisition, a three-dimensional reconstruction of the data was performed. The LIMA, LAD, first diagonal branch, and chest wall were stained different colors for better visualization. Surgery was performed using a left anterolateral mini-thoracotomy and through this access, the LIMA was dissected and anastomosed using a stabilizer without the use of extracorporal circulation. RESULTS: In all but one of the 18 patients who had a preoperative EBT, the minimally invasive direct coronary artery bypass (MIDCAB) procedure was successfully performed using an anterolateral mini-thoracotomy. Based on the results of the EBT, the 5 centimeter incision was done parasternally in six patients, and more laterally (2-4 cm parasternally) in the other eleven cases. In 13 patients the access penetrated the fourth intercostal space; in four cases the fifth intercostal space was used. In one patient EBT revealed a very laterally positioned and diffusely arteriosclerotic LAD so the patient was operated using a median sternotomy, but without the use of extracorporal circulation. In all 18 patients the preoperatively acquired information of the anatomical topography was confirmed intraoperatively. One case without a preoperative EBT had to be converted to a conventional procedure due to a small, intramyocardial LAD and a very small LIMA. Postoperative angiography revealed patent LIMA grafts and uneventful anastomoses. CONCLUSIONS: For minimally invasive direct coronary artery bypass (MIDCAB) the topography of the LIMA, LAD and intercostal spaces is of major importance. Using the ECG-triggered EBT with subsequent three-dimensional reconstruction these relationships can be visualized. This enables an individual planning of the operation and a minimalization of the skin incision.

Aged↗
PubMed1998

[Laparoscopic staging in abdominal tumors in children: an alternative to staging laparotomy].

INTRODUCTION: In abdominal tumors in childhood, staging laparotomy is usually an essential diagnostic tool to obtain information about the histology and the extension of the tumor, when less invasive methods do not reach to clarify the process. PATIENTS: In fourteen children between 3 months and 17 years a laparoscopical procedure was performed. MATERIAL AND METHOD: Only in patients without a clear diagnosis after noninvasive exploration were submitted to an explorative laparoscopy in order to define the histology, the extension of the illness or to locate it. The laparoscopical instrumentarium used was from Dufner, adapted to children. RESULTS: The patients tolerated well this procedure, the posoperative period was short (mean 2.07 days), no complications after the operation are reported. Only one case of hemorrhage lead to a conversion after biopsy of a neuroblastoma. In all cases the diagnosis and staging was achieved. CONCLUSIONS: When non invasive diagnostic methods are not conclusive an explorative laparoscopy should be performed because it offers a lot of advantages over a laparotomy.

Abdominal Neoplasms↗
PubMed1998

[Interactions between central opioidergic and cholecystokininergic systems in rats: possible significance for the development of of opioid tolerance].

Numerous data suggest that cholecystokinin (CCK) acts as an opioid-modulating peptide. Because pharmacological and behavioural studies have shown that CCK reduces the analgesic effects of opioids, an opioid-mediated activation of CCK-containing neurones has been proposed to be responsible for the development of opioid tolerance. In an attempt to directly assess this hypothesis, we have examined, in naive or morphine-tolerant/dependent rats, the possible influence of opioid-receptor ligands on--1 the release of CCK from spinal cord slices and--2 the extracellular levels of CCK in the frontal cortex in awake, freely moving animals. Whereas the stimulation of mu or delta 1 receptors inhibited the release of the peptide, the stimulation of delta 2 receptors increased CCK release. Morphine also increased CCK release, via an action at delta 2 receptors. The blockade of delta 1 receptors resulted in an enhancement of the peptide release, suggesting that endogenous opioids probably exert inhibitory tonic influence on CCK release through the stimulation of delta 1 receptors. In rats rendered tolerant/dependent, the inhibitory effects of opioids on CCK release, due to the stimulation of mu or delta 1 receptors, and the enhancing effect of delta 1 receptor blockade, were no longer present. In contrast, the delta 2-mediated increase in CCK release persisted. Thus, in morphine-tolerant/dependent rats, opioids apparently retain only their excitatory effects on CCK-containing neurones. These data support the idea that morphine exerts an excitatory influence on central CCKergic neurones, which could tend to reduce the analgesic action of the alkaloid, and are in line with the hypothesis that morphine tolerance/dependence is associated with an activation of CCK-containing neurones.

Analgesics, Opioid↗
PubMed1998

[Lesions of hollow organs in closed abdominal trauma--the value of computerized tomography].

INTRODUCTION: evaluation of the clinical and radiological criteria for laparotomy in intestinal lacerations after a blunt abdominal trauma. Determination of the different radiological signs from the CT scan and the sensitivity of this examination in the diagnosis of intestinal lacerations. DESIGN: retrospective study. MATERIAL AND METHOD: we selected all patients operated for intestinal laceration caused by a blunt abdominal trauma during the period of 1986 to 1995. The clinical and radiological criteria for laparotomy in these patients were determined. Correlation of the radiological signs from the CT-Scan and the surgical findings was used to determine the sensitivity of the CT-scan. We distinguished patients who had an abdominal CT-scan from those patients for which no CT was done.

Abdominal Injuries↗
PubMed1998

Biomechanical analysis and clinical treatment of blunt renal trauma.

The treatment of renal trauma is evolving and increasingly focusing on the nonoperative and expectant management. In this review the ongoing controversy concerning the diagnosis and management of major blunt renal trauma shall be revisited. The contribution also includes a biomechanical approach for analyzing the renal injury mechanisms using a computer-simulated model of the kidney. In this connection, results of the modelling and simulations of the kidney subjected to the external forces shall be presented. Based on these findings a bending mechanism is postulated that may be responsible for renal injuries. Finally, the role of injury biomechanics research in the clinical management of trauma patients as well as in the area of injury prevention is discussed.

Abdominal Injuries↗
PubMed1998

Epidemics and colonial medicine in west africa

We studied colonial medical practices and health policies in West Africa, which has faced endemics and epidemics that have affected entire societies. We found that attempts to centralize the organization of colonial medicine, which began in the late 19th Century, were limited until the end of World War I. Research and control programs expanded after 1920, concentrating on epidemics, but largely ignoring many major health problems, such as measles, whooping cough and malnutrition, the importance of which were not recognized until after World War II. This appraisal of colonial medicine highlights the difficulties of introducing modern medicine and its ideas into African societies. There have been various social reactions, resulting in the current duality in which traditional and modern medicine coexist.

Journal Article↗