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Biomedical subjects

G Becker

Publications and source records attributed to G Becker.

At least 181 records · Page 10Linked to original sources
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↗
PubMed1994

Reliability of transcranial colour-coded real-time sonography in assessment of brain tumours: correlation of ultrasound, computed tomography and biopsy findings.

Transcranial colour-coded real-time sonography (TCCS) was carried out in 25 patients with brain tumours to determine whether this noninvasive method provides additional information about the extent of solid tumour, its differentiation from oedema, and its tissue components. All 25 patients had serial computed tomography (CT)-guided stereotactic biopsies. Comparison of ultrasound, CT and histological findings revealed that the vast majority of contrast enhancing areas on CT were hyperechogenic (32/33; 97%) and contained tumour tissue (29/32; 91%). Hyperechogenic areas always represented solid tumour (23/23 patients), even when CT showed low density non-enhancing lesions. In lesions hypoechogenic on TCCS and low density on CT, histology consistently revealed necrotic tumour (7/7). Biopsies obtained from parenchyma with normal echogenicity revealed tumour in only 3 of 16 specimens. Despite the high specificity of TCCS in the differentiation of tumour components, its sensitivity to tumour was inferior to that of CT (24/25; 96%). TCCS thus allows noninvasive preoperative identification of tumour tissue and its extent setting.

Biopsy↗
PubMed1994

'Born to be a mother': the cultural construction of risk in infertility treatment in the U.S.

As American society has become increasingly medicalized, biomedically shaped constructions of risk have begun to dominate traditional cultural constructions. This paper examines how the quest for a pregnancy affects the construction of risk by women in infertility treatment in the United States. Findings are based on a longitudinal, qualitative study with 275 persons (132 couples and 11 women) who experienced infertility. Because women's involvement in medical treatment was greater than that of men and because they were more intent on treatment, women assumed the role of final arbiter of what was a risk, and which risks to take. Women perceived more risks than men and were more willing to take risks than men. Notions of risk changed for both women and men, however, as they proceeded through medical treatment. This research suggests that once infertility is medically designated as a disease, both patients and practitioners pursue a 'cure' through a well-delineated pattern of medical treatment, despite the risks of such treatment and independent of the likelihood of success. When medical views of risk and responsibility are teamed with women's persistence in the pursuit of a pregnancy, medical treatment may be taken to extremes. Americans consider risk-taking to be their prerogative when personal histories reflect strong cultural mandates about norms, values, rights, and responsibilities, and these in turn are interpreted as health-related by both consumers and health professionals. As a consequence, the forces that trigger medicalization are activated and medical technology is given potentially limitless scope.

Adult↗
PubMed1994

The gastrointestinal tract of the rock hyrax (Procavia habessinica). 1. Morphology and motility patterns of the tract.

The stomach of the rock hyrax (Procavia habessinica) is divided into a non glandular part with very slow movements, and a glandular part which rapidly mix the digesta. The large intestine has two fermentation chambers, the caecum, which rapidly mixes the digesta, and the colonic sac, which efficiently, but slowly, mixes digesta. Between these chambers runs the connecting colon. No retrograde transport is observed in any part of the large intestine.

Animals↗
PubMed1994

The oldest old; autonomy in the face of frailty.

Autonomy, a core American value, is routinely invoked as a goal in gerontological discussions of the aging process, yet frailty, another commonly used term in gerontology, suggests that functional losses may interfere with individuals' ability to maintain autonomy in everyday life. Older persons who are impaired are seldom asked how they view themselves with respect to autonomy and frailty, or what autonomy means. The meanings older persons attach to autonomy and decreases in physical abilities are explored through in-depth interviews with 28 persons age 80 or older. While autonomy encompassed a wide range of self-descriptions, respondents never used the word, frail, to describe themselves. I explore the potential of the construct of the lived body for a holistic approach to aging that values embodied knowledge and experiences of those who are old. I conclude that gerontological views of autonomy promote a cultural ideal that does not reflect elders' perspectives, and that the notion of frailty has the potential to stereotype elders, with negative effects on well being.

Aged↗
PubMed1994

Echogenicity of the brainstem raphe in patients with major depression.

A novel transcranial ultrasound technique was used to detect differences in the echogenicity and echotexture of the brainstem dorsal raphe nucleus in 20 patients with major depression compared with 20 age- and sex-matched healthy adults. Transcranial color-coded real-time sonography visualized the mesencephalic and pontine brainstem and its midline structure. The echogenicity of the raphe was classified in a four-point scale. Compared with healthy subjects, the depressed patients were characterized by a significant decrease in the echogenicity of the brainstem raphe. The echogenicity score was not correlated, however, with measures of psychopathology such as the Hamilton Rating Scale for Depression, the Clinical Global Impression Scale, the Global Assessment Scale, or the Depression Scale of von Zerssen. These preliminary findings suggest that the brainstem raphe may be involved in the etiopathogenesis of major depression. The echogenicity score should be further evaluated as a possible trait marker in different types of affective disorders.

Adult↗
PubMed1994

IDO mutants cross resistant to type I interferon retain p91-dependent gene induction.

Genetic analyses of mutants have yielded valuable information about p91-associated interferon signal transduction. It was thus discovered that p91 is an essential protein for the induction of both type I and type II interferons. We previously reported the development of ME180 mutants resistant to interferon-gamma because of a signaling defect resulting in the loss of IDO induction. IDO does not respond to type I interferon despite an ISRE-like sequence upstream of the coding region. However, the IDO mutants were found to be cross-resistant to the growth-inhibitory effects of type I interferon. We therefore examined the effects of both types of interferon on interferon-stimulated gene mRNA accumulation and examined alterations in cellular protein introduced by the mutation. The induction of the p91-responsive gene 6-16 was not altered in either of the mutants, and the early-induced gene IRF1 exhibited differences only in the kinetics of mRNA accumulation. The later induced gene, p68, also exhibited different kinetics, possibly reflecting the changes in IRF1. Immunoprecipitated p91 exhibited normal, interferon-induced phosphorylation in both mutants. Two-dimensional gel electrophoresis revealed that the mutant cells contained 20 peptides with altered biochemistry. These results suggest that IDO induction is controlled by a distinct set of proteins not directly correlated with p91 activation.

Cell Division↗