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Biomedical subjects

C Becker

Publications and source records attributed to C Becker.

At least 235 records · Page 13Linked to original sources
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↗
PubMed1998

[Rectal resection within the scope of multi-visceral interdisciplinary resection in the pelvis].

Multivisceral resectioning is the only curative treatment for progressive carcinomas extending beyond the organ. The results of 25 consecutively operated patients are presented in this prospective observational study. Twelve patients underwent surgery for a primary tumor and 13 for a recurrence. Radical resectioning was achieved in 5 of 12 and in 3 of 13 patients. Restoration of continuity obtained in 11 of 12 and in 7 of 13 patients. Morbidity was 33% and 62%. None of the patients died from complications. An aggressive surgical approach is justifiable on account of the acceptable morbidity and mortality as well as the high rate of preserved continence through modern reconstruction procedures.

Adult↗
PubMed1998

[Significance of prenatal diagnosis in interdisciplinary treatment of sacrococcygeal teratoma].

The perinatal treatment of 23 infants with sacrococcygeal teratomas was recorded prospectively from 1990 to 1997, during which period 14 children (teratomas 6.9-18 cm) could be followed throughout the whole pregnancy at our own perinatal department. There were three prenatal deaths (21 h-27 week of gestation) and two peripartal deaths (1 hydrops and 1 ruptured teratoma). Prenatal Doppler sonography allows appropriate selection of high-risk fetuses. The vital prognostic sign was developing fetal hydrops with associated umbilical vein pulsations, increased aortal flow and an increasing pulsatility index in der venous duct.

Abortion, Induced↗
PubMed1997

Lead based paint hazards in early childhood centres in the Wellington region.

AIM: To determine the frequency of exposure to lead based paint (LBP) in early childhood centres (ECCs) in the Wellington region. METHODS: Senior staff at sixty nine randomly selected licensed ECCs in the Wellington region were contacted. Fifty two centres consented to participate. Senior staff at these centres were interviewed and centres built before 1980 were examined for damaged LBP surfaces accessible to children. The survey was carried out between July 1995 and January 1996. A centre was considered to be LBP positive if it had at least one damaged LBP surface accessible to children in the course of a normal day's activities. RESULTS: Fifty two per cent of surveyed centres were LBP positive. LBP hazards were detected in 60% of buildings built before 1965 and 30% of buildings constructed between 1965 and 1980, and were found more frequently in Te Kohanga Reo and childcare centres. Although children aged 2 years and under constituted only 27% of all children attending surveyed centres, over half (53%) of the children in this age group attended centres with an LBP hazard. Staff at ECCs were often uncertain about the causes and outcomes of lead toxicity and expressed a desire for further education. CONCLUSION: There is significant potential for exposure to lead in early childhood centres in Wellington as a consequence of accessible damaged lead based paint surfaces.

Administrative Personnel↗
PubMed1997

Proteinase A, a storage-globulin-degrading endopeptidase of vetch (Vicia sativa L.) seeds, is not involved in early steps of storage-protein mobilization.

Proteinase A is a papain-like cysteine endopeptidase of vetch (Vicia sativa L.) which was assumed to initiate storage-globulin breakdown just after the onset of seed germination. This enzyme was purified from cotyledons of vetch seedlings. On gelatin-containg SDS gels, active proteinase A migrated with an apparent molecular mass of 21 kDa, whereas after heat denaturation its molecular size on SDS/PAGE was 29 kDa. Although proteinase A is capable of hydrolyzing storage globulins in vitro it could not be localized in the protein-body fraction of cotyledons from germinating seeds. cDNA clones encoding proteinase A precursor have been obtained by PCR. The precursor is composed of an N-terminal signal sequence followed by a propeptide, the region encoding mature proteinase A, and a C-terminal KDEL sequence. Mature proteinase A with a derived molecular mass of 25,244 Da does not have the KDEL sequence. The derived amino acid sequence of the proteinase A precursor is 78.2% identical to sulfhydryl-endopeptidase (SH-EP), a cysteine endopeptidase from germinating Vigna mungo seedlings. Northern blot analysis indicated that proteinase A mRNA appears de novo in cotyledons of 1-day-germinated vetch seeds, where its amount increases up to day 6. No proteinase A mRNA was detected in other vetch organs, not even in the embryo axis, which contains stored globulins. By means of antibodies raised against the purified and against recombinantly produced proteinase A, the 29-kDa bands of mature proteinase A were detected in cotyledon extracts of 6-day-germinated seeds when globulin degradation has already far proceeded. The reported data do not agree with the proposed triggering role of proteinase A in storage-globulin breakdown during germination.

Amino Acid Sequence↗
PubMed1997

Regulation of glucose transport, and glucose transporters expression and trafficking in the heart: studies in cardiac myocytes.

Cardiac muscle is characterized by a high rate of glucose consumption. In the absence of insulin, glucose transport into cardiomyocytes limits the rate of glucose utilization and therefore it is important to understand the regulation of glucose transporters. Cardiac muscle cells express 2 distinct glucose transporters, GLUT4 and GLUT1; although GLUT4 is quantitatively the more important glucose transporter expressed in heart, GLUT1 is also expressed at a substantial level. In isolated rat cardiomyocytes, insulin acutely stimulates glucose transport and translocates both GLUT4 and GLUT1 from an intracellular site to the cell surface. Recent evidence indicates the existence of at least 2 distinct intracellular membrane populations enriched in GLUT4 with a different protein composition. Elucidation of the intracellular location of these 2 GLUT4 vesicle pools in cardiac myocytes, their role in GLUT4 trafficking, and their relation to insulin-induced GLUT4 translocation needs to be addressed.

Animals↗
PubMed1997

Insulin-induced recruitment of glucose transporter 4 (GLUT4) and GLUT1 in isolated rat cardiac myocytes. Evidence of the existence of different intracellular GLUT4 vesicle populations.

UNLABELLED: Using isolated rat cardiomyocytes we have examined: 1) the effect of insulin on the cellular distribution of glucose transporter 4 (GLUT4) and GLUT1, 2) the total amount of these transporters, and 3) the co-localization of GLUT4, GLUT1, and secretory carrier membrane proteins (SCAMPs) in intracellular membranes. Insulin induced 5.7- and 2.7-fold increases in GLUT4 and GLUT1 at the cell surface, respectively, as determined by the nonpermeant photoaffinity label [3H]2-N-[4(1-azi-2,2,2-trifluoroethyl)benzoyl]-1, 3-bis-(D-mannos-4-yloxy)propyl-2-amine. The total amount of GLUT1, as determined by quantitative Western blot analysis of cell homogenates, was found to represent a substantial fraction ( approximately 30%) of the total glucose transporter content. Intracellular GLUT4-containing vesicles were immunoisolated from low density microsomes by using monoclonal anti-GLUT4 (1F8) or anti-SCAMP antibodies (3F8) coupled to either agarose or acrylamide. With these different immunoisolation conditions two GLUT4 membrane pools were found in nonstimulated cells: one pool with a high proportion of GLUT4 and a low content in GLUT1 and SCAMP 39 (pool 1) and a second GLUT4 pool with a high content of GLUT1 and SCAMP 39 (pool 2). The existence of pool 1 was confirmed by immunotitration of intracellular GLUT4 membranes with 1F8-acrylamide. Acute insulin treatment caused the depletion of GLUT4 in both pools and of GLUT1 and SCAMP 39 in pool 2. IN CONCLUSION: 1) GLUT4 is the major glucose transporter to be recruited to the surface of cardiomyocytes in response to insulin; 2) these cells express a high level of GLUT1; and 3) intracellular GLUT4-containing vesicles consist of at least two populations, which is compatible with recently proposed models of GLUT4 trafficking in adipocytes.

Animals↗
PubMed1997

Individual prostate-specific antigen (PSA) forms as prostate tumor markers.

Prostate-specific antigen (PSA) is a kallikrein-like serine protease mainly expressed in the human prostate. It is responsible for the proteolysis of the gel-forming proteins in human semen. Two major extracellular protease inhibitors, alpha-1-antichymotrypsin (ACT) and alpha-2-macroglobulin (AMG) may inactivate PSA escaping from the prostate. The predominant immunodetected form of PSA in serum is complexed to ACT but PSA exists also in a free non-complexed form despite the large excess of inhibitors. The concentrations of PSA in serum are normally less than 4 micrograms/l. but elevated concentrations are found in a majority of patients with prostate cancer (CAP) and the analysis of PSA in serum has become invaluable in the detection and monitoring of patients with CAP. However, it is not an ideal tumor marker in the sense that there are CAP patients with normal PSA concentrations in serum and patients with benign hyperplasia of the prostate (BPH) with elevated PSA concentrations. Analysis of the various PSA forms in serum attracts much interest as there is a higher proportion of PSA in complex with ACT in patients with CAP than in those with BPH. Optimal combinations of monoclonal antibodies have been used to design sensitive noncross-reacting immunoassays for the detection of free PSA, PSA-ACT complexes and the detection of both free PSA and PSA complexes in an equimolar fashion (i.e. total PSA). Several studies have demonstrated that the analysis of the proportions of the free-to-total PSA in serum may increase the diagnostic specificity by 15-20% without significant loss in the sensitivity for detection of CAP.

Biomarkers, Tumor↗
PubMed1997

Lack of correlation between rejection of tumor cells co-expressing interleukin-2 and B7.1 and vaccine efficiency.

Genetically modifying tumor cells to express a variety of cytokines such as interleukin-2 (IL-2) or the co-stimulatory molecule B7.1 leads to increased immunogenicity and reduced tumorigenicity of tumors in several models with T cells involved in the process. We have previously reported decreased tumorigenicity of the murine plasmacytoma J558L [major histocompatibility complex (MHC) class I+ and class II-] expressing IL-2 or B7.1. When systemic immunity was analyzed, immunization with either J558-IL2 or J558-B7.1 cells generated moderate protection against unmodified J558L tumor cells, comparable to immunization with a tumor cells/adjuvant Corynebacterium parvum mixture. In this study, we asked whether the co-expression of IL-2 and B7.1 in tumor cells would augment vaccine potency, cytotoxic T lymphocyte (CTL) activity and protective immunity. Rejection of single IL-2 or B7.1 or co-transfected IL-2/B7.1 cells occurred in most syngeneic animals but not in T cell-deficient nude mice, thus confirming that T cells were required for tumor rejection. We knew from previous experiments that CD8+ T cells were responsible for rejection. Surprisingly, immunization with J558-IL2/B7.1 cells followed by challenge with parental J558L caused a reduction in systemic protection as compared to J558-B7.1 or J558-IL2 alone. We examined the mechanism underlying this unexpected result: 6 days after injection of J558-IL2/B7.1 cells, tumor were nearly completely destroyed and were almost devoid of CD8+ cells, while CD8+ cells were increased in both IL-2- and B7.1-transfected tumors. In addition, immunization with J558-IL2/B7.1 tumors had an adverse effect on the generation of CTL. Mice immunized with J558-B7.1 and to a lesser extent J558-IL2 cells mounted a CTL response against J558L cells while, in contrast, no CTL activity could be detected in mice immunized with J558-IL2/B7.1, thus showing a correlation between the absence of CTL activity and the lack of in vivo protection. We demonstrate that "hyperstimulation" of the immune response by genetically modified cancer vaccines can have adverse effects on tumor immunity, even though the mechanism is not yet completely understood.

Animals↗
PubMed1997

Spiral CT angiography and 3D reconstruction in patients with aortic coarctation.

The objective of this study was to assess the reliability of spiral CT angiography (CTA) and 3D reconstruction in patients with aortic coarctation (CoA). Eighteen patients with suspected or surgically proven coarctation were examined by spiral CT. In addition to the axial slices, 3D reconstructions, such as shaded surface display (SSD) and maximum intensity projection (MIP), were used to determine the diameters of the CoA and the pre- and poststenotic aorta and to visualise the collateral vessels. Diameters derived from cardiac catheterization were compared with those from CTA in 8 patients. The degree of aortic stenosis was correlated with blood pressure gradients (BPG) in 12 patients. The difference between the diameters of the CoA and the pre- and poststenotic aorta derived from MIP and angiography was not statistically significant (p = 0.69). With SSD the internal thoracic artery was detected in 16 and the posterior intercostal artery in 13 cases. The degree of aortic stenosis correlated poorly with the BPG (r = 0.51, r2 = 0.26). CTA with 3D reconstruction represents a reliable noninvasive technique for the assessment of the degree of CoA and the visualisation of collateral vessels. It may serve as a follow-up investigation after intervention or surgical treatment.

Adolescent↗
PubMed1997

Non-invasive determination of cartilage thickness throughout joint surfaces using magnetic resonance imaging.

Data on articular cartilage thickness in the living are important for the design for computer models, aimed at preoperatively assessing the effect of surgical procedures on joint contact and load transmission, and for the calculation of cartilage material properties from its deformational behavior as determined during arthroscopy. A non-invasive method for measuring cartilage thickness in living subjects is, however, not available. A technique based on magnetic resonance imaging has therefore been tested for assessing articular cartilage thickness throughout joint surfaces. The accuracy is determined by comparing cartilage thickness maps obtained from three patellar specimens with a fat-suppressed three-dimensional gradient-echo sequence (resolution 2 x 0.31 x 0.31 mm) to those obtained with CT arthrography, A-mode ultrasound and anatomical sections. The distribution patterns are quantitatively compared using image analysis. The highest agreement was obtained for MRI and the sections (50% identical pixels), but all techniques yielded very similar results. On average, MR slightly underestimated the cartilage thickness compared with CT and the sections, and overestimated it compared with ultrasound. No evidence of differences in the degree of similarity could be detected in areas of thin and thick cartilage. We conclude that, if the resolution and accuracy of the method presented are considered acceptable, MRI is available for repeatable determination of topographical maps of articular cartilage thickness in living subjects. These data can be used to determine joint contact and stress in computer models and to calculate cartilage material properties in vivo.

Adult↗
PubMed1997

CD8+ tumor-specific Tc cells primed in vivo or in vitro against the BALB/c plasmacytoma ADJ-PC-5 use the same TcR V beta families but display distinct TC1 or TC2 characteristics.

The involvement of counteractive CD8+ T cell subsets in tumor-specific unresponsiveness was analyzed in a syngeneic murine tumor model. CD8+ cytotoxic T cells against the IL-10 producing BALB/c plasmacytoma ADJ-PC-5 can be easily induced in vitro, in a primary syngeneic mixed lymphocyte tumor cell culture (MLTC), or in vivo, by repeated immunization of syngeneic BALB/c mice with high doses of X-irradiated ADJ-PC-5 tumor cells. Long term cultivated CD8+ ADJ-PC-5-specific Tc lines use either TcR of the V beta 6 or V beta 8.1/8.2 type, irrespective if the lines were derived from a primary MLTC or from immunized mice. While most of the Tc lines produce type-1 cytokines (IFN-gamma, no IL-4) upon stimulation, at least two of them, which were derived from a primary MLTC, display a type-2 cytokine spectrum (IL-4, no IFN-gamma). The primary in vitro Tc response against ADJ-PC-5 cells shows characteristics of a TC2 response: CD8+ Tc cells which 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 lowest numbers of irradiated ADJ-PC-5-specific TC1 cells via IFN-gamma, these TC1 cells behave similar to a previously described regulatory subset of IFN-gamma producing CD8+ T cells, which are induced during early stages of ADJ-PC-5 tumorigenesis and inhibit the induction of a tumor-specific Tc response from naive BALB/c spleen cells in vitro.

Adjuvants, Immunologic↗
PubMed1997

A non-invasive technique for 3-dimensional assessment of articular cartilage thickness based on MRI. Part 2: Validation using CT arthrography.

Established methods for the measurement of articular cartilage thickness are invasive and cannot be sequentially applied in living subjects. In the present study, the distribution of cartilage thickness throughout entire joint surfaces was determined from MR images obtained with a fat-suppressed gradient-echo sequence at a resolution of 0.31 x 0.31 x 2.00 mm3, and compared to that derived from CT arthrography. A minimal distance algorithm was employed to produce 3D cartilage thickness maps of seven cadaveric human knee joints. The mean amount of deviation of the cartilage volumes was 5.6% (+/- 4.6), statistical analysis showing that there was high agreement between the two methods (r = 0.995, slope = 1.037, y-intercept = -90.5 mm3). The 3D thickness maps yielded a striking agreement between the two methods, the maximum values generally yielding a deviation of none or one thickness interval of 0.5 mm. This investigation shows that accurate 3D assessment of articular cartilage thickness can be performed with MRI, this technique having the advantage that it is suitable for investigating living subjects.

Adult↗