Search PubMed⌕ Search

Biomedical subjects

G Becker

Publications and source records attributed to G Becker.

At least 217 records · Page 12Linked to original sources
PubMed1992

Cervical pheochromocytoma: a rare localization and a difficult diagnosis.

A 45-year-old hypertensive female with insulin-treated diabetes mellitus presented to our clinic with elevated urinary norepinephrine (NE) concentrations and a negative 131-metaiodobenzylguanidine (MIBG) scintigraphy, errouneously limited to the abdomen, for evaluation of a pheochromocytoma (Pheo). Despite antihypertensive medications blood pressure remained highly variable and frequently elevated. Further biochemical testing, including a glucagon provocation test and a clonidine-suppression test, revealed autonomous NE secretion. In order to avoid repeat MIBG-scintigraphy, other non invasive imaging techniques were performed, including real time sonography (7.5 MHz) of the neck which revealed a tumor. Fine needle aspiration of this tumor tissue demonstrated cells compatible with Pheo. Histology and immunohistochemistry of the excised tumor confirmed the diagnosis of Pheo. After surgical removal of the tumor, urinary and plasma NE levels normalized. Without any medication the blood pressure of the patient was now only slightly hypertensive. Only half of the daily insulin dose was needed to maintain the patient euglycemic.

Adrenal Gland Neoplasms↗
PubMed1992

Computer systems and mechanical tools for stereotactically guided conformation therapy with linear accelerators.

An integrated system for fractionated, stereotactically guided conformation radiotherapy has been developed. The system components are a stereotactic fixation system that can be used each treatment day, a localization, and positioning unit that can be used during x-ray computer tomography, magnetic resonance imaging, positron emission tomography, and radiographical examinations as well as for treatment. Conformal precision radiotherapy is planned with a new three-dimensional treatment planning system (Voxel-Plan-Heidelberg) which comprises, among others options, a three-dimensional image correlation procedure as well as routines for the calculation of coplanar and non-coplanar irradiations with irregularly shaped fields. Two different multi-leaf collimators have been designed for precision radiotherapy in the head and neck region. A manual multi-leaf collimator is used for irradiations with stationary beams or for moving beam treatments with invariable irregularly shaped fields. This collimator system is now being used for patient treatments. The design of a computer controlled multi-leaf collimator unit for multiple fixed field irradiation techniques is discussed. All system components are aimed at conforming dose distributions for fractionated radiotherapy treatments to the target to improve sparing of adjacent normal tissues, and at achieving a sufficient geometrical accuracy in the dose application.

Computer Systems↗
PubMed1992

Transcranial color-coded real-time sonography in the evaluation of intracranial neoplasms and arteriovenous malformations.

Transcranial color-coded real-time sonography (TCCS) was performed in 57 patients with primary intracranial brain tumors (n = 49) or arteriovenous malformations (n = 8) to evaluate its diagnostic potential. In 46 patients (81%), lesions could be identified employing this technique. In 7 patients, transcranial ultrasound examination was not feasible because of bone thickness; in the remaining 4 patients, the tumor was indistinguishable from adjacent brain tissue despite sufficient insonation, suggesting that these neoplasms are isoechogenic. The sonographic features of brain tumors were very similar: a hyperechogenic matrix of the lesion was interspersed by hypoechogenic pixels. Larger hypoechogenic areas (0.5-1 cm) gave evidence of tumor necrosis. Differences between the findings of TCCS and computed tomography concerning tumor size were found in 7 patients, in whom TCCS revealed an area of smaller extension within the corresponding hypodense area on the computed tomographic scan. Perifocal brain edema could not be detected by ultrasound examination. In 13 patients, a thin, hypoechogenic peritumoral halo was disclosed that did not correlate with perifocal brain edema identified by computed tomography and that may have been due to compression of adjacent parenchyma. In patients with arteriovenous malformations, TCCS permitted the identification of the main feeders, the nidus, and the draining venous system by color-coded depiction of intravascular blood flow. In conclusion, TCCS is an additional method for initial diagnosis and highly suitable for follow-up in tumor patients and provides valuable information about tissue characteristics and blood flow.

Adult↗
PubMed1992

Clinical markers of asthma severity and risk: importance of subjective as well as objective factors.

The purpose of this study was to explore patient perceptions of asthma severity and danger from asthma, correlate them with objective measures, and assess the impact of psychologic variables on the perception of severity. Recognition of patients at greatest risk for fatal attacks requires identifying those with severe asthma. In our study of 95 adults with asthma, we found that the subjective factors of perceived severity and perceived danger and the objective factors of medications, hospitalizations, history of intubation, and pulmonary function were important markers of asthma severity and risk. Our findings indicate that asthmatic adults make independent self-assessments that generally correlate with objective markers of increased risk of mortality and increased severity of the asthma. The perception of high severity was significantly correlated with depression, panic-fear, frequency of emergency department visits, and with an objective index of risk of death. The latter includes variables obtainable from history alone (number of medications to control symptoms, need for prednisone, prior intubation, and prior recent hospitalization) and is correlated with spirometric indexes of airflow obstruction, occurrence of nocturnal symptoms, and number of emergency department visits.

Adult↗
PubMed1992

The effects of gender-specific diagnosis on men's and women's response to infertility.

OBJECTIVE: To determine if differences could be distinguished between men's and women's emotional response to infertility based on the assignment of a gender-specific diagnosis. DESIGN: Gender-specific diagnoses were examined in relation to stigma, perception of loss, role failure, and self-esteem, using structured interviews. SETTING: Tertiary clinical care in private practice settings. PARTICIPANTS: Thirty-six self-selected volunteer couples undergoing infertility treatment. MAIN OUTCOME MEASURES: Stigma, perception of loss, role failure, and lowered self-esteem emerged from content analysis of structured interview data. RESULTS: No differences were found among women in their emotional response to infertility regardless of whether a female or male infertility factor was present, whereas men with a male factor experienced more negative emotional response to infertility than men without a male factor. CONCLUSIONS: Although both women and men are affected by infertility, their emotional response is significantly influenced by a gender-specific diagnosis. Men's response to infertility closely approximates that of women if the infertility has been attributed to a male factor but differs considerably if a male factor is not found.

Emotions↗
PubMed1991

Incorporation of synthetic peptide helices in membranes of tetraether lipids from Thermoplasma acidophilum. A calorimetric study.

Four analogues of the membrane-modifying, alpha-helical polypeptide antibiotic alamethicin were synthesized. the alpha-helical deca-, undeca-, heptadeca-, and icosapeptides were mixed with the main tetraether lipid of the Archaebacterium Thermoplasma acidophilum (MPL), dipalmitoylphosphatidylcholine (DPPC) and dihexadecylmaltosylglycerol (DHMG) in various ratios and the modification of the lipid phase transition was determined by differential thermal analysis (DTA). The polypeptides form mixed phases with MPL and DPPC, however, not with DHMG. Heptadeca- and icosapeptide exert a much stronger reduction of enthalpy (delta H) than deca- and undecapeptide and bind about 0.5 molecule of MPL (or one molecule of DPPC) per peptide molecule. delta H of the DPPC pretransition is reduced by the deca- and the undecapeptides and completely disappears with heptadeca- and icosapeptides (at 0.2 mole of peptide/mole of lipid). The modulation of the melting point Tm by the incorporation of peptides is more pronounced with MPL than with DPPC, the heptadecapeptide exhibiting the strongest reduction (with MPL) and the strongest broadening of the transition peak (with DPPC). Helix length, amphiphilicity and charge of the polypeptides can be correlated with the observed modifications of the lipid phase transitions.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1991

Human papillomavirus and c-myc/c-erbB2 in uterine and vulvar lesions.

The aim of this study was to investigate papillomavirus (HPV)-DNA in precancer and cancer of the cervix, vulva, and endometrium by in situ/dot blot/Southern blot hybridization and polymerase chain reaction (PCR). Myc/erbB-2 expression was examined by Northern blot analysis. PCR was the most sensitive HPV detection method, demonstrating HPV-DNA in all pre-invasive and invasive cervical lesions (n = 21) and most (3 of 4) vulvar carcinomas in contrast to an overall rate of 60% with other techniques. Particular phenotypes (adenoid cystic/basal cell carcinoma of the vulva, cervical adenocarcinoma) were found to contain HPV. Endometrium harboured HPV not only in two cases of cervical cancer, but also in 3 of 8 primary endometrial carcinomas and 3 of 8 non-malignant conditions. Myc activation was confined to three squamous cell carcinomas, most markedly in one HPV-6-positive verrucous variant. ErbB-2 over-expression was only seen in one HPV-18 infected advanced endometrial tumour. Our findings point to a range of HPV-infected lesions broader than previously supposed and possible contributions of HPV-independent molecular events to carcinogenesis in this field.

Base Sequence↗
PubMed1991

Omega-oxidized leukotriene B4 detected in the broncho-alveolar lavage fluid of patients with non-cardiogenic pulmonary edema, but not in those with cardiogenic edema.

Leukotriene (LT) generation has been implicated in the pathogenesis of the acute respiratory distress syndrome, ARDS. In the present study, we analysed broncho-alveolar lavage fluids of patients on mechanical ventilation because of ARDS (17 samples taken from 9 patients) or because of cardiogenic edema (8 samples taken from 6 patients) and of healthy volunteers (10 samples from different donors). LTs were separated as methylated and non-methylated compounds using different HPLC procedures, and were identified by chromatographic mobility, on-line UV-spectrum analysis and post HPLC immunoreactivity. In the lavage samples of the healthy volunteers and the patients with cardiogenic edema, no LTs were detected by these techniques (detection limit congruent to 0.1-0.2 ng/ml lavage fluid). By contrast, in 15 out of 17 samples from patients with ARDS LTB4 or its metabolites 20-OH-LTB4 and 20-COOH-LTB4 were detected. The endproduct of omega-oxidation, 20-COOH-LTB4, represented the quantitatively predominant compound, detected in the range of 0.3-2.6 ng/ml perfusate. We conclude that the chemotactic agent LTB4 may be involved in the amplification of inflammatory events encountered in ARDS, and that the oxidized metabolites of LTB4 are particularly suitable for monitoring lung leukotriene generation under conditions of neutrophil efflux and oxidative stress.

Adult↗
PubMed1991

Modification of a three-dimensional treatment planning system for the use of multi-leaf collimators in conformation radiotherapy.

The multi-leaf collimator of the DKFZ is designed as a low cost add-on device for conventional linear accelerators for radiotherapy. The technical specification of the computer controlled collimator is described briefly. A major limitation in the use of the wide capabilities of multi-leaf collimators in the clinic is still an appropriate treatment planning system. This paper describes treatment planning and dose calculation techniques for multi-leaf collimators and shows examples where the capabilities of the collimator are used extensively.

Dose-Response Relationship, Radiation↗
PubMed1991

Ambiguous responsibility in the doctor-patient relationship: the case of infertility.

The effects of ambiguous responsibility in the doctor-patient relationship on persons undergoing medical treatment for infertility are examined through the negotiation process that ensues following diagnosis. Through the analysis of 79 interviews with women and men undergoing infertility treatment, it was found that: (1) diagnosis reinforced individuals' sense of responsibility for their infertility; (2) ambiguity in the doctor-patient relationship affected shifts in patients' perception of physician responsibility, and (3) patients eventually re-established responsibility for their medical treatment. The implications of ambiguous responsibility for symbolic meanings in biomedicine and the way those meanings are linked to power and authority are explored through an examination of power in patient and physician roles, clinical uncertainty, and medical competence.

Clinical Competence↗
PubMed1991

[Transcranial color-coded real-time sonography in the adult. 1: Normal findings and cerebrovascular ischemia].

Transcranial colour-coded real time sonography (TCCS) is a new, non-invasive diagnostic bedside procedure allowing two-dimensional imaging of cerebral parenchymatous structures and large intracranial arteries through the intact skull. So far we examined a population of 183 patients und 53 normal subjects, all above 18 years of age. 24 (10%) subjects were not suitable for examination. Two-dimensional imaging of telencephalic, diencephalic, mesencephalic and pontine structures is feasible. Intravascular blood flow phenomena may be analysed quantitatively by an integrated pulsed wave Doppler system. The diagnosis of arterial stenosis and occlusion could be established in 14 patients each by analysing the colour-coded B-mode image and Doppler frequency spectrum. TCCS may complement diagnostic tools in neurology and may improve standardisation of transcranial Doppler measurements.

Adult↗
PubMed1991

[Transcranial color-coded real time sonography in adults. Part 2: Cerebral hemorrhage and tumors].

We examined three groups of adult patients to evaluate the clinical application of transcranial colour-coded real-time sonography (TCCS): 28 patients suffering from intracerebral haemorrhage, 36 patients with subarachnoid haemorrhage and 38 patients with primary brain tumours. All sonographic examinations were performed through the intact skull. Cerebral haemorrhages were visualised via TCCS as hyperechogenic areas, which were closely correlated in size and location to CT findings. Apart from the imaging of subarachnoid haemorrhages and cerebral vasospasms, TCCS permitted the identification of the angiographically confirmed aneurysms in 76%. Brain tumours were delineated in the vast majority of the patients examined. In this type of pathology TCCS provided additional information on tumour extension and macroscopic appearance.

Adult↗
PubMed1991

Content and boundaries of medicine in long-term care: physicians talk about stroke.

Twenty physicians were interviewed about roles, treatments, goals, and relationships with older patients, especially stroke patients. Findings from this descriptive, anthropological investigation address the problem of congruence between needs and existing services, and in doing so, recast the ongoing debate about the medicalization of long-term care. This study emphasized the nonmedical features of geriatric medicine in general and stroke care in particular. In many instances, these physicians attempt to bridge gaps between medical and emotional needs and clinical and social services with social and psychotherapeutic as well as biomedical interventions. Because we found physicians' activities with stroke patients to be so broadly construed, treatment and management of stroke may be seen as paradigmatic for the role of physicians in long-term care.

Aged↗
PubMed1991

Diagnosis and monitoring of subarachnoid hemorrhage by transcranial color-coded real-time sonography.

Thirty-six patients with acute spontaneous subarachnoid hemorrhage (26 caused by rupture of an aneurysm) were examined by transcranial color-coded real-time sonography by using a 2.25-MHz ultrasound transducer. In 20 of these 26 patients (76%), the aneurysm could be identified by a characteristic abnormal blood flow pattern within the aneurysm in coronal and axial scanning planes by transcranial color-coded real-time sonography. Blood within the basal cisterns, on top of the tentorium, and within the ventricles and parenchyma was sonographically detected by increased echodensity in 75%. In addition, cerebrospinal fluid circulation disturbances and cerebral vasospasm were detected in two-dimensional B-mode images in 85% and 100%, respectively. In Doppler mode, intravascular blood flow velocity could be quantified. We conclude that transcranial color-coded real-time sonography, a new, noninvasive method for diagnosis and follow-up of patients with subarachnoid hemorrhage, allows detection of the primary vascular lesion and monitoring of complications.

Blood Flow Velocity↗