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Biomedical subjects

G Becker

Publications and source records attributed to G Becker.

At least 55 records · Page 3Linked to original sources
PubMed2000

Transcranial sonography: integration into target volume definition for glioblastoma multiforme.

PURPOSE: Recent studies indicate that transcranial sonography (TCS) reliably displays the extension of malignant brain tumors. The effect of integrating TCS into radiotherapy planning for glioblastoma multiforme (GBM) was investigated herein. METHODS AND MATERIALS: Thirteen patients subtotally resected for GBM underwent TCS during radiotherapy planning and were conventionally treated (54 to 60 Gy). Gross tumor volumes (GTVs) and stereotactic boost planning target volumes (PTVs, 3-mm margin) were created, based on contrast enhancement on computed tomography (CT) only (PTV(CT)) or the combined CT and TCS information (PTV(CT+TCS)). Noncoplonar conformal treatment plans for both PTVs were compared. Tumor progression patterns and preoperative magnetic resonance imaging (MRI) were related to both PTVs. RESULTS: A sufficient temporal bone window for TCS was present in 11 of 13 patients. GTVs as defined by TCS were considerably larger than the respective CT volumes: Of the composite GTV(CT+TCS) (median volume 42 ml), 23%, 13%, and 66% (medians) were covered by the overlap of both methods, CT only and TCS only, respectively. Median sizes of PTV(CT) and PTV(CT+TCS) were 34 and 74 ml, respectively. Addition of TCS to CT information led to a median increase of the volume irradiated within the 80% isodose by 32 ml (median factor 1.51). PTV(CT+TCS) volume was at median 24% of a "conventional" MRI(T2)-based PTV. Of eight progressions analyzed, three and six occurred inside the 80% isodose of the plans for PTV(CT) and for PTV(CT+TCS), respectively. CONCLUSION: Addition of TCS tumor volume to the contrast-enhancing CT volume in postoperative radiotherapy planning for GBM increases the treated volume by a median factor of 1.5. Since a high frequency of marginal recurrences is reported from dose-escalation trials of this disease, TCS may complement established methods in PTV definition.

Adult↗
PubMed2000

Spinal canal stenosis in L-2-hydroxyglutaric aciduria.

We describe 2 brothers with L-2-hydroxyglutaric aciduria who developed severe spastic tetraparesis in their 30s. They also had an underlying condition of high-grade cervical spinal canal stenosis diagnosed by magnetic resonance imaging. They were operated on to decompress the spine, and the preexisting gait disturbances slowly diminished after the decompression. Since most people with L-2-hydroxyglutaric aciduria show spastic signs in their legs and arms, we conclude that cervical spinal canal stenosis may be the underlying reason and may be linked to this rare metabolic disorder.

Adult↗
PubMed2000

The correlation between ventricular diameter measured by transcranial sonography and clinical disability and cognitive dysfunction in patients with multiple sclerosis.

CONTEXT: Magnetic resonance imaging (MRI) data suggest that the extent of brain atrophy in patients with multiple sclerosis (MS) is related to the severity of disease. OBJECTIVE: To evaluate whether ventricular diameter determined by transcranial sonography (TCS) is a marker of brain atrophy and is correlated with disability, cognitive performance, and mood. SUBJECTS AND METHODS: We examined 74 subjects with MS and 74 age- and sex-matched control subjects with TCS and assessed the transverse diameter of the third ventricle and the frontal horns of the lateral ventricles. Quantitative neurological examination was performed in subjects with MS using the Expanded Disability Status Scale. All subjects with MS underwent MRI, the Brief Repeatable Battery of Neuropsychological Tests for MS, and standardized tests for mood disorders. RESULTS: Transcranial sonographic measurements of ventricular diameter closely matched MRI measurements (Spearman rank correlation, r=0.7-0.9; P<.01). The ventricular diameters were significantly larger in subjects with MS than in healthy age- and sex-matched control subjects. The measurement of the diameter of the third ventricle obtained by TCS or MRI and the measurement of disability obtained with the Expanded Disability Status Scale were significantly correlated (Spearman rank correlation, r = 0.4; P<.01). The correlation between the diameter of the frontal horns and disability was substantially lower for both neuroimaging techniques. In addition, TCS and MRI data correlated significantly with the majority of neuropsychological tests; no correlation was found between the diameter of the ventricles and depression scales. CONCLUSION: As ventricular diameter is related to the status of disability and may also indicate disease progression, we propose measurement of the diameter of the third ventricle with TCS as a quick and easy surrogate marker for serial follow-up examinations in patients with MS.

Adult↗
PubMed2000

Transfer of patients with acute myocardial infarction for primary or acute angioplasty from hospitals without the facilities to perform angioplasty. Results from the pooled data of the Maximal Individual Therapy in Acute Myocardial Infarction (MITRA) Registry and the Myocardial Infarction Registry (MIR).

In patients with acute myocardial infarction (AMI) admitted at hospitals without angioplasty facilities there are some subgroups of patients which seem to profit from a transfer to primary or acute angioplasty. However, current clinical practice at such hospitals is unknown. We analyzed the pooled data of the German acute myocardial infarction registries MITRA and the MIR. Angioplasty was not available at 221/271 hospitals (81.5%). Out of 14,487 patients with acute myocardial infarction admitted to these hospitals, 50.1% (7,259/14,487) received thrombolysis at the initial hospital and 3.6% (523/14,487) were transferred. Out of the transferred patients, 55.3% (289/523) were treated with primary angioplasty and 44.7% (234/523) received a combination of thrombolysis and angioplasty. The proportion of transferred patients increased from 1.1% in 1994 to 5.5% in 1998 (p for trend = 0.001). One hundred and four hospitals (47.1%) never transferred patients. Patients transferred for primary angioplasty (289 patients) were compared to patients treated with thrombolysis at the initial hospitals (7,259 patients). Multivariate analysis showed the following independent predictors for transfer of patients for primary angioplasty: contraindications for thrombolysis (OR = 17.9), a non-diagnostic first ECG (OR = 4.0), pre-hospital delay > 6 hours (OR = 2.5), unknown symptom onset of the acute myocardial infarction (OR = 2.0) and anterior wall acute myocardial infarction (OR = 1.6). Heart failure at admission was the only independent predictor not to transfer patients (OR = 0.40). In Germany only 47.1% of hospitals without angioplasty facilities transfer patients with acute myocardial infarction to primary or acute angioplasty. The proportion of transferred patients increased from 1.1% in 1994 to 5.5% in 1998. Contraindications for thrombolysis were the strongest predictor to transfer patients to primary angioplasty.

Aged↗
PubMed2000

The basal ganglia in haemochromatosis.

Haemochromatosis is characterised by deposition of iron-containing pigment in various organs, but little is known about possible deposition in the brain and its clinical impact. We therefore investigated 14 patients with hereditary haemochromatosis with MRI, CT and transcranial ultrasound (TCS) and examined them neurologically. In six of the patients dense lesions were found within the lentiform nucleus on CT, all of whom displayed hyperechogenic lesions in the same area on TCS, as did one other patient. In these patients the relative signal intensities of the lentiform nucleus measured by MRI relaxometry were higher. No patient had clinical signs of basal ganglia disorders.

Adult↗
PubMed2000

Activity of extracranial metastases as a prognostic factor influencing survival after radiosurgery of brain metastases.

Information about prognostic factors influencing survival have been only occasionally reported in studies on the use of radiosurgery in the treatment of patients with brain metastasis. To answer the question of whether activity of extracranial metastases is an independent prognostic factor influencing survival in radiosurgery of brain metastases, a review of the literature was performed. Fourteen studies were identified in the English language literature that dealt with this topic. Only three studies showed borderline insignificance of the influence of activity of extracranial metastases when analysed by univariate methods. When multivariate analysis was used to test for the independent influence of this factor on survival, of nine studies that used that statistical approach eight showed that it is an independent prognosticator influencing survival, most often being the strongest one. This review of literature supports the view that the "activity of extracranial metastases" is an independent prognostic factor influencing survival of these patients as documented in published reports. However, prospective randomised trials are necessary to definitely establish the independent influence of this prognostic factor.

Analysis of Variance↗
PubMed2000

Early postoperative transcranial sonography (TCS), CT, and MRI after resection of high grade glioma: evaluation of residual tumour and its influence on prognosis.

PURPOSE: In this prospective study the results of multimodal postoperative neuro-imaging were related to the survival of patients with high grade gliomas. METHODS: All 73 patients included underwent microsurgical tumour resection and had postoperative CT and transcranial sonography (TCS) examinations. In addition, 35 of the 73 patients received an early postoperative MRI. Patients were followed up for at least one year. FINDINGS: At the end of the 7 year study period 56 patients had died. The median survival time was 371 days. Survival rate was significantly higher in patients with anaplastic astrocytomas and inpatients displaying complete tumour resection on MRI (log-rank-test, p < 0.05) or a small postoperative residual tumour bulk on TCS (log-rank-test, p < 0.05). Cox proportional hazards model identified histological tumour grade, postoperative Karnofsky index, complete resection based on MRI and small postoperative residual tumour mass on TCS as independent predictors of survival. INTERPRETATION: This study demonstrates that early postoperative neuro-imaging has prognostic implications for the survival of patients with high grade gliomas. According to our results postoperative imaging with MRI and TCS is a valuable prognostic with regard to patient survival and should therefore be implemented in postoperative follow-up. It also helps to evaluate the efficacy of adjuvant therapy.

Adolescent↗
PubMed2000

The Whitaker test, a useful tool in renal grafts?

OBJECTIVES: To evaluate the Whitaker test, a pressure flow examination, for its prognostic value in dilated renal transplants because urologic complications, such as ureteral stenosis, are significant problems after kidney transplantation. METHODS: Twenty-five patients with obstruction of the renal transplant and subsequent percutaneous nephrostomy were evaluated with a urodynamic pressure flow test (Whitaker test) in combination with antegrade pyeloureterography. The results of the Whitaker test were related to the serum creatinine values. RESULTS: The Whitaker test demonstrated normal pressure flow (less than 15 cm H(2)O) in 7 patients, pressure flow between 15 and 25 cm H(2)O in 10, and pathologic results (greater than 25 cm H(2)O) in 8 patients. After percutaneous nephrostomy, the serum creatinine level decreased in 22 of 25 patients, although the urodynamic pressure flow revealed a significant obstruction (Whitaker test greater than 25 cm H(2)O) in only 8 patients. The sensitivity of the Whitaker test to indicate the relevance of post-renal transplant stenosis in comparison to the declining serum creatinine level after successful percutaneous nephrostomy was 79%; the specificity was 50%. CONCLUSIONS: The results of our study indicate that a decreasing creatinine level in correlation with radiologic results is the leading finding in dilation of transplanted kidneys without rejection. The Whitaker test, as a pressure flow examination, provided no additional information.

Adolescent↗
PubMed2000

Transcranial sonography of the brain parenchyma: comparison of B-mode imaging and tissue harmonic imaging.

Transcranial color-coded Duplex sonography (TCCS) has been used for the identification of cerebrovascular disorders. Recently, its value in the diagnosis of disorders of the brain parenchyma has been proposed. The object of this study was to determine systematically the echo pattern of the brain parenchyma and to compare conventional B-mode imaging with tissue harmonic imaging (THI). Transcranial sonography (TCS) was performed in 54 healthy individuals through the temporal bone window using conventional B-mode imaging and THI by two experienced investigators. Identification rates for several brain structures were assessed, and the quality of depiction of each method was graded semiquantitatively. In addition, several parts of the ventricular system and the basal cerebral cisterns were measured. Four subjects did not have an adequate bone window for transcranial examination. In the remaining people, the bone window was assessed to be adequate (59%) or excellent (33%). In the majority (> 80%), TCS allowed an unequivocal identification of various brain structures. Inter-rater variability of the assessments of tissue echogenicity and measurements of the ventricular width were found to be low for several structures (e.g., brainstem, thalamus, or 3rd ventricle). The echo pattern of brain tissue in THI is identical to that described for B-mode imaging. Using THI, contours of brain structures were typically visualized more clearly and the reproducibility of measurements was more consistent. In our experience, insonation of the contralateral lobes was limited when depths were higher than 12 cm using THI. In conclusion, TCS allowed the sonographic examination of the brain parenchyma in the majority of our subjects. THI substantially improves the identification of parenchymal structures when the depth is below 12 cm.

Adult↗
PubMed2000

Dependency of the [18F]fluoromisonidazole uptake on oxygen delivery and tissue oxygenation in the porcine liver.

We have previously shown that the accumulation of fluorine-18-labeled fluoromisonidazole ([(18)F]FMISO) is inversely correlated to tissue oxygenation, allowing the quantification of porcine liver tissue hypoxia in vivo. We determined the activity from administered [(18)F]FMISO in relation to the hepatic oxygen availability and the partial pressure of oxygen in tissue (tPO(2)) to define a critical oxygen delivery on a regional basis. [(18)F]FMISO was injected 2 h after onset of regional liver hypoxia due to arterial occlusion of branches of the hepatic artery in 10 domestic pigs. During the experimental procedure the fractional concentration of inspired oxygen (FiO(2)) was set to 0.67 in group A ( N=5) and to 0.21 in group B ( N=5) animals. Immediately before sacrifice, the tPO(2) was determined in normal flow and flow-impaired liver segments. The standardized uptake values (SUV) for [(18)F]FMISO was calculated from 659 single tissue samples obtained 3 h after injection of approximately 10 MBq/kg body weight [(18)F]FMISO and was compared with the regional total hepatic oxygen delivery (DO(2)) calculated from the regional arterial and portal venous flow (based on (141)Ce- and (99m)Tc-microspheres measurements) and the oxygen content of the arterial and portal venous blood. In 121 tPO(2)-measured liver tissue samples, the mean DO(2) was significantly decreased in occluded liver tissue samples [group A: 0.063 (0.044-0.089); group B: 0.046 (0.032-0.066)] compared to normal flow segments [group A: 0.177 (0.124-0.252); group B: 0.179 (0.128-0.25) mL x min(-1) x g(-1); geometric mean (95% confidence limits); p < 0.01 in group A and p < 0.001 in group B]. The tPO(2) of occluded segments [group A: 5.1 (3.2-8.1); group B: 3.9 (2.4-6.2) mm Hg] was significantly decreased compared to normal flow segments [group A: 20.2 (12.6-32.5); group B: 22.4 (14.3-35.2) mm Hg; p < 0.01 in group A and p < 0.001 in group B]. Three hours after [(18)F]FMISO administration, the mean [(18)F]FMISO SUV determined in tPO(2)-measured occluded segments was significantly higher [group A: 4.08 (3.12-5.34), group B: 5.43 (4.14-7.13)] compared to normal liver tissue [group A: 1.57 (1.2-2.06), group B: 1.5 (1.16-1.93); p < 0.001 for both groups]. The [(18)F]FMISO SUV allowed prediction of the tPO(2) with satisfying accuracy in hypoxic regions using the exponential regression curve [[(18)F]FMISO=1.05+6.7((-0.117 tPO(2))); r(2)=0.75; p < 0.001]. In addition, regardless of ventilation conditions, a significant exponential relationship between the DO(2) and the [(18)F]FMISO SUV was found ( r(2)=0.39, p < 0.001). Our results suggest that the reduction of the oxygen delivery below the critical range of 0.1-0.11 mL x min(-1) x g(-1) regularly causes liver tissue hypoxia. The severity of hypoxia is reflected by the [(18)F]FMISO accumulation and allows the in vivo estimation of the tPO(2) in hypoxic regions.

Animals↗
PubMed2000

Health, welfare reform, and narratives of uncertainty among Cambodian refugees.

Massive disruptions to a way of life, such as those brought on by widespread violence, terror, and genocide, disorder the body as well as the social order. When they flee their homelands, refugees bring their experiences of violence and terror with them. Drawing on an ethnographic study of 40 Cambodian refugees between the ages of 50 and 79 who suffered from one or more chronic illnesses, we explore how refugees who live with chronic illnesses and are dependent on government support were affected by the threat of welfare reform. When welfare reform threatened to cut Cambodian refugees' income, it posed a new crisis for those who were chronically in limbo and placed further constraints on their lives. Through their narratives, Cambodian refugees enacted their bodily distress and resisted the threat of welfare reform. The story of threatened welfare reform in the U.S. and its possible consequences for refugees is a story of quixotic U.S. politics, policies and antidotes for refugeeism gone awry.

Aged↗
PubMed2000

How important is transient error in estimating reliability? Going beyond simulation studies.

This article introduces a procedure for estimating reliability in which equivalent halves of a given test are systematically created and then administered a few days apart so that transient error can be included in the error calculus. The procedure not only estimates complete reliability (taking into account both specific-factor error and transient error) but also can estimate partial reliability (taking into account only specific-factor error). Scores from 6 different measuring instruments were analyzed with the procedure. The results indicate that the magnitude of transient error in real data can range from nonexistent to very large. It follows that traditional reliability estimates, using nonstaggered procedures, are inflated to the extent that transient error is present.

Adult↗
PubMed2000

The response regulator RssB, a recognition factor for sigmaS proteolysis in Escherichia coli, can act like an anti-sigmaS factor.

sigmaS (RpoS) is the master regulator of the general stress response in Escherichia coli. Several stresses increase cellular sigmaS levels by inhibiting proteolysis of sigmaS, which under non-stress conditions is a highly unstable protein. For this ClpXP-dependent degradation, the response regulator RssB acts as a recognition factor, with RssB affinity for sigmaS being modulated by phosphorylation. Here, we demonstrate that RssB can also act like an anti-sigma factor for sigmaS in vivo, i.e. RssB can inhibit the expression of sigmaS-dependent genes in the presence of high sigmaS levels. This becomes apparent when (i) the cellular RssB/sigmaS ratio is at least somewhat elevated and (ii) proteolysis is reduced (for example in stationary phase) or eliminated (for example in a clpP mutant). Two modes of inhibition of sigmaS by RssB can be distinguished. The 'catalytic' mode is observed in stationary phase cells with a substoichiometric RssB/sigmaS ratio, requires ClpP and therefore probably corresponds to sequestering of sigmaS to Clp protease (even though sigmaS is not degraded). The 'stoichiometric' mode occurs in clpP mutant cells upon overproduction of RssB to levels that are equal to those of sigmaS, and therefore probably involves binary complex formation between RssB and sigmaS. We also show that, under standard laboratory conditions, the cellular level of RssB is more than 20-fold lower than that of sigmaS and is not significantly controlled by stresses that upregulate sigmaS. We therefore propose that antisigma factor activity of RssB may play a role under not yet identified growth conditions (which may result in RssB induction), or that RssB is a former antisigma factor that during evolution was recruited to serve as a recognition factor for proteolysis.

Adenosine Triphosphatases↗
PubMed2000

Uninterrupted moderately accelerated radiotherapy in the treatment of unresectable/advanced head and neck cancer: one institution's experience and a comparative review.

Conventional radiotherapy alone in treatment of unresectable or locally advanced head and neck cancer has poor results. To improve outcome without significant increase in acute and late morbidity, we began a moderately accelerated hyperfractionation radiation therapy protocol without breaks for treatment of unresectable/advanced head and neck malignancies. From August 1984 to June 1995, 48 patients with unresectable or advanced carcinoma of the head and neck were treated using a protocol of accelerated hyperfractionation radiation therapy at Kaiser Permanente Medical Center, Los Angeles. Patients were treated twice a day using 150 cGy per fraction, 4 days per week, to a final dose of 60 Gy. Two patients were excluded from this analysis because they did not complete treatment. With a median follow-up of 33 months, 31 (67%) patients have had disease recurrence, 30 (65%) of whom had a locoregional component to their failures. At the last follow-up, 12 patients (26%) were alive with no evidence of disease, 30 patients had died of disease, and 4 had died of intercurrent disease without recurrence. Nine (19%) patients required treatment interruptions averaging 8 days in duration. This accelerated regimen resulted in outcomes similar to those with conventional radiotherapy, most likely because of a conservative total dose. Further refinement of fractionation schedules with potential incorporation of chemotherapy must be investigated.

Adult↗
PubMed2000

Measurement of cerebral blood flow volume by extracranial sonography.

Measurement of global cerebral blood flow (CBF) using extracranial duplex sonography has been described, but normal values are still lacking. In 85 healthy adults (median age 43.4 years, range 20 to 80 years), CBF was determined by duplex sonographic examination of both internal carotid arteries and vertebral arteries. The mean global CBF was 630+/-97 mL/min. Global CBF declined with age; sex did not influence the total CBF. When measurements were repeated, the intraindividual variability was low. This noninvasive sonographic measurement of CBF is reproducible, and values correspond closely to those obtained with positron emission tomography and magnetic resonance imaging.

Adult↗
PubMed2000

Combined treatment effects after embolization and radiosurgery in high-grade arteriovenous malformations. Case report and review of the literature.

In recent years the multimodal therapy concept has been established for high-grade intracerebral arteriovenous malformations (AVM). One strategy of a multimodal treatment approach for patients with AVM (Spetzler grade V) is reported. After endovascular embolization, the patient underwent radiosurgical treatment of the remaining nidus with a linear accelerator, after which he developed a left-sided hemiparesis in conjunction with severe edema. Angiographic control 44 months after radiation showed an occlusion of the radiosurgically treated nidus. The remaining nidus could be removed by microsurgery. The combination of embolization and radiosurgery may provoke prolonged edema and permanent neurological deficits due to inflammatory perivascular changes.

Adult↗
PubMed2000

Lesion pattern in patients with multiple sclerosis and depression.

To assess if a specific lesion pattern or changes of the basal limbic system as seen in primary depression and depression associated with neurodegenerative disorders might be identified in depressive multiple sclerosis (MS) patients, we submitted 78 MS patients to a MRI examination consisting of a quantitative measurement of lesions and of hyperintense signals from the pontomesencephalic midline (raphe). Furthermore relaxometry of the pontomesencephalic midline, a transcranial ultrasound examination rating its echogenicity semiquantitatively and a standardized neurological, neuropsychiatric and neuropsychological assessment were obtained. Thirty-one patients fulfilled the DSM-IV criteria for depression. Depressed MS patients had a significantly larger temporal lesion load than non-depressed MS patients, especially on the right side. A trend of difference was detected for lesions of the right parietal lobe, the right frontal lobe, the cerebellum and the total lesion load. Neither hyperintense signals or relaxometry nor echogenicity of the region at the level of the pontomesencephalic midline were significantly different between the groups. We conclude that depression in MS patients is not associated with an alteration of the basal limbic system at the brainstem as seen in Parkinson's disease or unipolar depression but with an increased lesion load of the projection areas of the basal limbic system.

Adult↗