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Biomedical subjects

G Becker

Publications and source records attributed to G Becker.

At least 37 records · Page 2Linked to original sources
PubMed1995

Abdominal wall metastasis following percutaneous endoscopic gastrostomy.

Percutaneous endoscopic gastrostomy (PEG) has become a widely used method for nutritional support, particularly in patients with advanced head and neck carcinomas. Since the method is easy and widely established it is necessary to assess possible complications, even rare ones. In this paper we report on two patients with vaccination metastasis following PEG insertion. Both patients had advanced squamous cell carcinoma of the head and neck or the upper esophagus. In three patients previous bougienage was performed, because of considerable stenosis of the pharynx and/or esophagus. Fast-growing metastases were found at the site of PEG insertion, with and without involvement of the gastric wall. In neither case was abdominal wall metastasis the cause of death. There is a small but definite risk of tumor seeding into the abdominal wall after PEG insertion for obstructive malignant tumors. The clinical impact of this finding, however, is still undefined and needs further investigation.

Abdominal Muscles↗
PubMed1995

Some methodological issues in neuroradiological research in psychiatry.

An outline is given of some of the methodological issues discussed in neuroradiological research on psychiatric illness. Strengths and shortcomings of magnetic resonance imaging (MRI) in depicting and quantifying brain structures are described. Temporal lobe anatomy and pathology are easily accessible to MRI, whereas limits on anatomical delineation hamper approaches to frontal lobe study. White matter hyperintense lesions are sensitively depicted by MRI, but specificity is limited. Distinction of vascular and primary degenerative dementia is considerably improved by CT and MRI analysis. Computed tomography (CT) and MRI have enhanced the understanding of treatable organic psychiatric disorders, e.g., normal pressure hydrocephalus. Subcortical and white matter pathology has been replicated in CT and MRI studies of late-onset psychiatric disorders, clinical overlap with cerebrovascular disease or neurodegeneration may be of import. Transcranial sonography findings of brainstem structural change specific to unipolar depression may contribute to the understanding of affective psychoses. Magnetic resonance spectroscopy and functional MRI are likely to stimulate psychiatric research in the future.

Brain↗
PubMed1995

The gastrointestinal tract of the rock hyrax (Procavia habessinica). 2. Fluid flow, production of short chain fatty acids and absorption of water and electrolytes.

In the digestive tract of the rock hyrax (Procavia habessinica), water is absorbed from the small intestine and from the wider part of the connecting colon running between the caecum and the colonic sac. Only little water absorption occurs from these two fermenting chambers. The outflow from the caecum is much higher than from the colonic sac mainly due to the effective absorption in the connecting colon with its very large absorptive area. A significant lower osmolality was found in the caecal contents compared with the contents in the colonic sac. The Na/K ratio was 10.7 and 1.7, respectively in these sections. Short chain fatty acids are produced at a rate of nearly 10 mmol/100 ml/hr in the contents of both the caecum and the colonic sac. The results are discussed in relation to the findings in domestic and laboratory animals.

Animals↗
PubMed1995

Preoperative and postoperative follow-up in high-grade gliomas: comparison of transcranial color-coded real-time sonography and computed tomography findings.

Twenty patients with high-grade gliomas were prospectively studied by pre- and postoperative transcranial color-coded real-time sonography (TCCS) and CT, to determine the sensitivity of TCCS in the identification of residual tumor and tumor regrowth. Each patient was subjected to preoperative and early postoperative CT (postoperative day 1) and TCCS examinations (postoperative days 6 to 8) and subsequent CT and TCCS follow-up examinations within a time interval of 6 weeks to 3 months. In eight patients, a total of 15 biopsy specimens were intraoperatively obtained from the wall of the resection cavity. Histological findings of intraoperative biopsy specimens showed that hyperechogenic areas adjacent to the resection cavity always contained residual tumor tissue. Early postoperative TCCS identified these hyperechogenic areas in 19 of 20 patients. In 12 patients, postoperative CT revealed contrast enhancement at the resection margin, indicating residual tumor. In these patients the extension of these hyperechogenic areas on TCCS exceeded the contrast-enhancing areas on CT by a mean of 58%. In eight patients, postoperative CT displayed no contrast enhancement along the border of resection. TCCS and histological findings indicated residual tumor in seven of these eight patients. The size of the hyperechogenic lesions identified by postoperative TCCS increased in time and follow-up examinations revealed that tumor regrowth arose from these hyperechogenic areas in all patients. In four patients, tumor regrowth was identified, on average 0.7 months earlier by TCCS than by CT. From these data we conclude that the sensitivity of TCCS in detection of residual tumor and tumor regrowth seems to be superior to CT. The value of TCCS requires further clarification by comparative studies including histology and MRI.

Biopsy↗
PubMed1995

Transcranial color-coded real-time sonography of intracranial veins. Normal values of blood flow velocities and findings in superior sagittal sinus thrombosis.

Sonographic findings in patients with superior sagittal sinus thrombosis were compared to those in healthy adults. Two patients with angiographically verified superior sagittal sinus thrombosis were examined by transcranial color-coded real-time sonography (TCCS) after intravenous application of a pulmonary stable ultrasound contrast agent. For comparison, 10 patients without venous pathology had contrast-enhanced TCCS; in addition, 30 healthy adults had plain TCCS to determine the identification rate for deep and superficial venous segments and to define normal values of venous blood flow velocities. The straight sinus was identified in 22 of 30 healthy subjects by plain TCCS, and in 9 of 10 patients by contrast-enhanced TCCS. The mean peak and angle-corrected blood flow velocity was 19.1 +/- 7.1 cm/sec. The superior and inferior sagittal sinuses were identified by contrast-enhanced TCCS in 2 and 1 subjects, respectively; they were never seen on plain TCCS. In the 2 patients with sagittal sinus thrombosis a distinct increase of blood flow velocity was recorded from the straight sinus (83 and 92 cm/sec), most likely reflecting collateral circulation. These preliminary data indicate that TCCS and particularly contrast-enhanced TCCS permit identification and blood flow measurements within the deep and occasionally, the superficial venous system. TCCS may contribute to an assessment of hemodynamic repercussions of venous thrombosis and may indicate the risk of venous infarction and hemorrhage.

Adult↗
PubMed1995

ELISA technique for quantification of surfactant protein B (SP-B) in bronchoalveolar lavage fluid.

Surfactant protein B (SP-B) is one of the essential constituents of the alveolar surfactant system, presenting mainly in the form of SP-B dimer. The measurement of this molecule in biologic samples has been hampered by its extreme hydrophobicity and intimate association with surfactant lipids. We developed a solid-phase, adsorption-based enzyme-linked immunosorbent assay (ELISA) technique for the quantification of SP-B in aqueous solutions. The ELISA employs the hydrophobicity of SP-B for direct binding of this compound to polystyrol immunosorbent plates. Samples are mixed with propanol (1:1 vol/vol) to achieve a homogeneous dispersion of their lipophilic constituents prior to adsorption to the wells. After fluid removal by evaporation, trifluoroethanol is added to optimize SP-B-polystyrol binding, and is then removed, again by evaporation. Subsequent washing procedures (diisopropyl-ether/butanol; Tween 20 in phosphate buffered saline [PBS]) selectively remove phospholipids. Solid phase-bound SP-B is detected by a monoclonal mouse antibody against porcine SP-B, cross-reacting with the apoprotein of human origin. For amplification, a biotinylated anti-mouse antibody and the avidin/biotin-peroxidase technique are used. Steep calibration curves with an excellent reproducibility are obtained for SP-B dimer (range: 0.3125 to 40 ng/well), either introduced directly into the immunosorbent-plate wells or previously admixed with synthetic phospholipid mixtures. SP-B monomer is detected with approximately 10% efficiency as compared with the dimer (wt/wt). Cross-reactivities with human SP-A and SP-C or albumin are negligible. Experiments with spiking of human bronchoalveolar lavage fluid (BAL) samples with different quantities of SP-B dimer revealed virtually complete apoprotein recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1995

Degeneration of substantia nigra in chronic Parkinson's disease visualized by transcranial color-coded real-time sonography.

To detect morphologic abnormalities in Parkinson's disease (PD), we examined 30 patients with PD and 30 age- and sex-matched nonparkinsonian controls by transcranial color-coded real-time sonography (TCCS). In 12 severely affected PD patients, the echogenicity of the substantia nigra was distinctly increased. In the remaining 18 PD patients and in all controls, the substantia nigra was poorly visualized or nondetectable by TCCS. The degree of hyperechogenicity of the substantia nigra closely correlated with the severity and duration of PD (p < 0.001). The increased echogenicity of the substantia nigra notably results from nigral gliosis and reflects the stage of degeneration.

Aged↗
PubMed1995

Managing an uncertain illness trajectory in old age: patients' and physicians' views of stroke.

Uncertainty is a central feature of a chronic illness trajectory, resulting from questions about the effects of the illness on daily life, what symptoms mean, and what the future holds. When chronic illness occurs late in life, uncertainty is magnified, and serious questions arise about whether the individual will be able to weather the disruption and go on with daily life. This article examines illness trajectories from two vantage points, that of older persons who have had a stroke and that of physicians who care for stroke patients, by means of interviews with 36 persons who had strokes and with 20 physicians. Physicians' views of stroke were informed not only by knowledge of physiological processes but also by biomedical ideologies and cultural meanings associated with their patients' ages and impairments. People who had strokes focused on recovery; they assumed the trajectory was open to manipulation if they worked hard enough. The vague medical response to uncertainty affected patients' interpretations; what they were not told shaped their expectations about recovery as much as what they were told. The uncertain trajectory of stroke in old age is one example of how illness experience is affected by cultural attitudes about age, biomedical ideologies, the provision of health care services, and economically driven health policies. The anticipation of recovery by persons who have had strokes and the letdown when recovery does not occur reflect critical dilemmas in biomedicine and in society itself that have implications for health policy.

Activities of Daily Living↗
PubMed1995

[Bicentric stereotaxic convergent-beam irradiation].

PURPOSE: Circular collimated X-ray beams rotated in various non-coplanar planes as commonly used in stereotactic linac-based radiotherapy are generating spherical dose distributions with typically steep dose gradients. In case of irregular, especially elongated lesions, this technique fails to conform the shape of the corresponding planning target volume, and a collimator aperture has to be selected which allows for an acceptable dose distribution only on the expense of an excess dose to a larger amount of normal tissue. Therefore we have investigated a bicentric irradiation technique with sequentially treating an elongated target volume over two separated isocenters. METHODS: For the computer simulation studies we used the planning system of the stereotactic unit SRS-200 by Philips. Selected combinations of different collimator aperture were examined systematically by varying the distance between the two isocenters. Dose distributions for a specially developed head-phantom were calculated and analysed. RESULTS: Optimization tables were generated taking into account the geometric quality criteria as well as the corresponding dose maxima. For a given size of the target volume, the appropriate parameters for the bicentric radiation treatment can be chosen. The calculated dose distributions turned out to be independent of the positioning of the two isocenters within the phantom. CONCLUSION: The optimization tables serve to select a set of starting values for the interactive planning process of an elongated target volume resulting in a significant decrease of the overall time for treatment planning of irregular shaped lesions.

Film Dosimetry↗
PubMed1995

[The status of transcranial color-coded real time ultrasound in diagnosis of cerebral lesions].

Transcranial color-coded real-time sonography (TCCS) combines transcranial Doppler sonography and color-coded B-mode scanning of the brain parenchyma and cerebral vessels. This technique is not invasive and a broad spectrum of intracerebral lesions such as vascular lesions (ischemic stroke and intracerebral hemorrhage, aneurysms, arteriovenous malformations, arteriosclerotic vascular degeneration) and parenchymal lesions (brain tumors, degenerative and neuropsychiatric disorders) can be disclosed. Compared with MRI and CT, the ultrasound system is movable. Thus, it can be used easily in emergency rooms and intensive care units. In addition, TCCS can disclose new insights into the pathophysiology of disorders of the CNS, as in neuropsychiatric diseases. Ultrasound contrast agents improve the depiction of intracranial vessels. The pathology of the venous system can be identified.

Adult↗
PubMed1994

Functional role of bicarbonate in propionate transport across guinea-pig isolated caecum and proximal colon.

1. Unidirectional fluxes of propionate across isolated epithelia from the guinea-pig caecum and proximal colon were measured under short-circuit current conditions. In the caecum and proximal colon the serosal-to-mucosal propionate flux (JPrsm) was higher than mucosal-to-serosal flux (JPrms), resulting in a net secretory flux of propionate. 2. HCO3(-)-CO2-free solution reduced JPrms in the caecum and proximal colon markedly; JPrsm was not (caecum) or little (proximal colon) affected. The subsequent addition of acetazolamide caused a further decrease in JPrms in the proximal colon, but not in the caecum. 3. In HCO3(-)-containing solutions acetazolamide or ethoxzolamide inhibited JPrms; JPrsm was not affected. A macromolecular carbonic anhydrase inhibitor, prontosil-dextran, had no effect on propionate fluxes, indicating that the intracellular carbonic anhydrase is of importance for short-chain fatty acid transport. 4. Subsequent to carbonic anhydrase inhibition, mucosal addition of amiloride caused a slight further decrease of JPrms in the caecum and proximal colon; JPrsm was not affected. 5. Results support the view that a considerable proportion of short-chain fatty acids (SCFAs) is absorbed via a SCFA(-)-HCO3- exchange.

Acetazolamide↗
PubMed1994

Gender-controlled measures of socially desirable responding.

Items in various scales that measure socially desirable responding (SDR) appear to vary in significance in male and female respondents. Recent findings suggest that females are more sensitive to the contents of more than two-thirds of such items. As a result, scales that measure SDR cannot be considered gender balanced, not to mention gender free. We examined three levels at which SDR items can be construed as gender controlled and arrived at a formula for item selection in the development of gender-controlled scales. Application of the formula resulted in the 10-item Gender-Free Inventory of Desirable Responding (GFIDR), with an inter-item reliability of .68, and the 12-item Gender Balanced Inventory of Desirable Responding (GBIDR), with an inter-item reliability of .71. The distribution characteristics of the two scales suggested that gender differences in the higher moments should be considered in the interpretation of results based on otherwise gender-controlled scales.

Adult↗
PubMed1994

Contribution of transcranial color-coded real-time sonography to the etiopathogenetic classification of middle cerebral artery stenosis.

Transcranial color-coded real-time sonography (TCCS) and cranial computed tomography were applied to patients with middle cerebral artery (MCA) stenosis to evaluate whether these techniques may disclose additional aspects of the pathophysiology of the stenotic lesion. In 15 patients with MCA stenosis identified by transcranial Doppler sonography, the echogenicity of the stenotic segment was estimated subjectively by TCCS. The density of the stenotic segment, prior to being detected by TCCS, was quantified by computed tomography. In 5 of the 15 patients, transcranial image-directed Doppler sonography identified a hyperechogenic lesion in association with the stenotic vascular segment; computed tomography demonstrated a "dense" artery (Hounsfield units [HU] > 120) in the corresponding vascular segment. In 10 patients the echogenicity of the stenotic segment was found to be normal, with a computed tomography density of < 100 HU in the corresponding segment. Hyperechogenic and hyperdense stenotic vascular segments in TCCS and computed tomography, respectively, may indicate an arteriosclerotic vascular lesion with calcium deposits. Normal echogenicity and normal to slightly elevated computed tomography-density of a stenotic vascular segment may suggest the presence of a thrombotic/embolic lesion.

Adolescent↗
PubMed1994

Cloning, structure, cellular localization, and possible function of the tumor suppressor gene lethal(3)malignant blood neoplasm-1 of Drosophila melanogaster.

The tumor suppressor gene, lethal(3)malignant blood neoplasm-1+, of Drosophila melanogaster is required for the differentiation of the phagocytic blood-cell type, the plasmatocyte. In the homozygously mutated state it causes the malignant transformation of these blood cells. We present here the cloning, sequencing, structure, and expression of the l(3)mbn-1+ gene during development. The cloned gene was identified by germ-line transformation, generation of revertants, and the detection of the corresponding mRNA in blood cells and other tissues. Homologies of the G-S-rich C-terminus of the putative MBN83 protein to human cytokeratins K1, K10, and mouse loricrin were found. The structure and possible function of the wild-type l(3)mbn-1+ gene are discussed.

Alleles↗