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Biomedical subjects

T Becker

Publications and source records attributed to T Becker.

At least 55 records · Page 3Linked to original sources

In vivo evidence for differential association of striatal dopamine and midbrain serotonin systems with neuropsychiatric symptoms in Parkinson's disease.

Parkinson's disease affects various neurotransmitter systems. Using SPECT, the authors measured [(123)I]beta-CIT binding ratios of the caudate, putamen, medial thalamus, and dorsal midbrain over cerebellum in 16 patients with Parkinson's disease, and examined correlations with clinical ratings. Whereas striatal binding ratios (reflecting regional dopamine transporter densities) were associated with motor symptoms, dorsal midbrain binding ratios (reflecting regional serotonin transporter densities) were significantly correlated with the mentation, behavior, and mood subscale of the Unified Parkinson's Disease Rating Scale. These findings indicate that degeneration of the nigrostriatal dopaminergic neurons and a dysfunctional serotonergic raphe system contribute differentially to motor deficits and neuropsychiatric symptoms in Parkinson's disease.

Adult↗

Early screening for dyslexia--a collaborative pilot project.

An ongoing collaborative project, currently being piloted in 12 Wiltshire primary schools, is described. The aim is to provide a means of identifying potentially dyslexic children by the end of Key Stage 1 (Year 2) with a view to early intervention. The causal links identified by research between phonological skills and literacy development are taken as the theoretical basis of an initial screening procedure, and an intervention package is implemented for identified children. Those demonstrating persistent difficulties one year later are further assessed over a school term using an assessment package designed to identify those children showing a dyslexic profile. Further intervention is then planned and implemented.

Child, Preschool↗

Gradients of ephrin-A2 and ephrin-A5b mRNA during retinotopic regeneration of the optic projection in adult zebrafish.

Regeneration of optic axons in the continuously growing optic system of adult zebrafish was analyzed by anterograde tracing and correlated with the mRNA expression patterns of the recognition molecules ephrin-A2 and ephrin-A5b in retinal targets. The optic tectum and diencephalic targets are all reinnervated after a lesion. However, the rate of erroneous pathway choices was increased at the chiasm and the bifurcation between the ventral and dorsal brachium of the optic tract compared to unlesioned animals. Tracer application to different retinal positions revealed retinotopic reinnervation of the tectum within 4 weeks after the lesion. In situ hybridization analysis indicated the presence of rostral-low to caudal-high gradients of ephrin-A2 and ephrin-A5b mRNAs in unlesioned control tecta and after a unilateral optic nerve lesion. By contrast, the parvocellular superficial pretectal nucleus showed retinotopic organization of optic fibers but no detectable expression of ephrin-A2 and ephrin-A5b mRNAs. However, a row of cells delineating the terminal field of optic fibers in the dorsal part of the periventricular pretectal nucleus was intensely labeled for ephrin-A5b mRNA and may thus provide a stop signal for ingrowing axons. Ephrin-A2 and ephrin-A5b mRNAs were not detectable in the adult retina, despite their prominent expression during development. Thus, given a complementary receptor system in retinal ganglion cells, expression of ephrin-A2 and ephrin-A5b in primary targets of optic fibers in adult zebrafish may contribute to guidance of optic axons that are continuously added to the adult projection and of regenerating axons after optic nerve lesion.

Age Factors↗

Proviral insertions in the zebrafish hagoromo gene, encoding an F-box/WD40-repeat protein, cause stripe pattern anomalies.

The zebrafish, Danio rerio, has three types of pigment cells (melanophores, xanthophores and iridophores) and, in adult fish, these cells are organized into a stripe pattern. The mechanisms underlying formation of the stripe pattern are largely unknown. We report here the identification and characterization of a novel dominant zebrafish mutation, hagoromo (hag), which was generated by insertional mutagenesis using a pseudotyped retrovirus. The hag mutation caused disorganized stripe patterns. Two hag mutant alleles were isolated independently and proviruses were located within the fifth intron of a novel gene, which we named hag, encoding an F-box/WD40-repeat protein. The hag gene was mapped to linkage group (LG)13, close to fgf8 and pax2.1. Amino acid sequence similarity, conserved exon-intron boundaries and conserved synteny indicated that zebrafish hag is an ortholog of mouse Dactylin, the gene mutated in the Dactylaplasia (Dac) mouse [1]. The Dac mutation is dominant and causes defects in digit formation in fore- and hindlimbs. This study revealed that the hag locus is important for pattern formation in fish but is involved in distinct morphogenetic events in different vertebrates.

Amino Acid Sequence↗

Tenascin-R inhibits regrowth of optic fibers in vitro and persists in the optic nerve of mice after injury.

Tenascin-R, an extracellular matrix constituent expressed by oligodendrocytes and some neuronal cell types, may contribute to the inhibition of axonal regeneration in the adult central nervous system. Here we show that outgrowth of embryonic and adult retinal ganglion cell axons from mouse retinal explants is significantly reduced on homogeneous substrates of tenascin-R or a bacterially expressed tenascin-R fragment comprising the epidermal growth factor-like repeats (EGF-L). When both molecules are presented as a sharp substrate border, regrowing adult axons do not cross into the tenascin-R or EGF-L containing territory. All in vitro experiments were done in the presence of laminin, which strongly promotes growth of embryonic and adult retinal axons, suggesting that tenascin-R and EGF-L actively inhibit axonal growth. Contrary to the disappearance of tenascin-R from the regenerating optic nerve of salamanders (Becker et al., J Neurosci 19:813-827, 1999), the molecule remains present in the lesioned optic nerve of adult mice at levels similar to those in unlesioned control nerves for at least 63 days post-lesion (the latest time point investigated), as shown by immunoblot analysis and immunohistochemistry. In situ hybridization analysis revealed an increase in the number of cells expressing tenascin-R mRNA in the lesioned nerve. We conclude that, regardless of the developmental stage, growth of retinal ganglion cell axons is inhibited by tenascin-R and we suggest that the continued expression of the protein after an optic nerve crush may contribute to the failure of adult retinal ganglion cells to regenerate their axons in vivo.

Animals↗

American College of Cardiology/European Society of Cardiolgoy International Study of Angiographic Data Compression Phase II: the effects of varying JPEG data compression levels on the quantitative assessment of the degree of stenosis in digital coronary angiography. Joint Photographic Experts Group.

OBJECTIVES: This report describes whether lossy Joint Photographic Experts Group (UPEG) image compression/decompression has an effect on the quantitative assessment of vessel sizes by state-of-the-art quantitative coronary arteriography (QCA). BACKGROUND: The Digital Imaging and Communications in Medicine (DICOM) digital exchange standard for angiocardiography prescribes that images must be stored loss free, thereby limiting JPEG compression to a maximum ratio of 2:1. For practical purposes it would be desirable to increase the compression ratio (CR), which would lead to lossy image compression. METHODS: A series of 48 obstructed coronary segments were compressed/decompressed at CR 1:1 (uncompressed), 6:1, 10:1 and 16:1 and analyzed blindly and in random order using the QCA-CMS analytical software. Similar catheter and vessel start- and end-points were used within each image quartet, respectively. All measurements were repeated after several weeks using newly selected start- and end-points. Three different sub-analyses were carried out: the intra-observer, fixed inter-compression and variable inter-compression analyses, with increasing potential error sources, respectively. RESULTS: The intra-observer analysis showed significant systematic and random errors in the calibration factor at JPEG CR 10:1. The fixed inter-compression analysis demonstrated systematic errors in the calibration factor and recalculated vessel parameter results at CR 16:1 and for the random errors at CR 10:1 and 16:1. The variable inter-compression analysis presented systematic and random errors in the calibration factor and recalculated parameter results at CR 10:1 and 16:1. Any negative effect at CR 6:1 was found only for the calibration factor of the variable inter-compression analysis, which did not show up in the final vessel measurements. CONCLUSIONS: Compression ratios of 10:1 and 16:1 affected the QCA results negatively and therefore should not be used in clinical research studies.

Adult↗

American College of Cardiology/European Society of Cardiology International Study of Angiographic Data Compression Phase III: measurement of image quality differences at varying levels of data compression.

OBJECTIVES: We sought to investigate up to which level of Joint Photographic Experts Group JPEG) data compression the perceived image quality and the detection of diagnostic features remain equivalent to the quality and detectability found in uncompressed coronary angiograms. BACKGROUND: Digital coronary angiograms represent an enormous amount of data and therefore require costly computerized communication and archiving systems. Earlier studies on the viability of medical image compression were not fully conclusive. METHODS: Twenty-one raters evaluated sets of 91 cine runs. Uncompressed and compressed versions of the images were presented side by side on one monitor, and image quality differences were assessed on a scale featuring six scores. In addition, the raters had to detect pre-defined clinical features. Compression ratios (CR) were 6:1, 10:1 and 16:1. Statistical evaluation was based on descriptive statistics and on the equivalence t-test. RESULTS: At the lowest CR (CR 6:1), there was already a small (15%) increase in assigning the aesthetic quality score indicating "quality difference is barely discernible-the images are equivalent." At CR 10:1 and CR 16:1, close to 10% and 55%, respectively, of the compressed images were rated to be "clearly degraded, but still adequate for clinical use" or worse. Concerning diagnostic features, at CR 10:1 and CR 16:1 the error rate was 9.6% and 13.1%, respectively, compared with 9% for the baseline error rate in uncompressed images. CONCLUSIONS: Compression at CR 6:1 provides equivalence with the original cine runs. If CR 16:1 were used, one would have to tolerate a significant increase in the diagnostic error rate over the baseline error rate. At CR 10:1, intermediate results were obtained.

Adult↗

Sleep position, bedding and heating practices in high- and low-risk ethnic groups for unexpected death in infancy (UDI).

UNLABELLED: In a previous study, a significant increased risk for unexpected death in infancy (UDI) among Arab infants as compared to Jews (RR: 5.2) was found. The incidence has significantly decreased in both groups during the 'back to sleep' campaign. The objective of this study was to compare the prevalence of three risk factors, i.e. positioning, night dressing/covering and heating practices in these ethnic groups. A community sampling procedure was employed, resulting in the participation of 264 Jewish and 146 Arab mothers of infants between 1 and 4 months, born at term and with no chronic illness at the time of the study. A questionnaire in Arabic and Hebrew was designed, pertaining to sleep positioning at the time of the study and of the previous infant, prior to the SIDS prevention campaign, as well as clothing and heating practices. Significantly, more Arab infants were put to sleep in a supine or side position as compared to Jewish infants both during the study (p = 0.002) as well as prior to the SIDS campaign (p = 0.001). No ethnic difference was related to clothing practices. Open heating, however, was significantly more common in the Arab sector (p = 0.001). A logistic procedure for each of the practices indicated that ethnicity is related significantly to both sleep position (p = 0.002) and beating practices (p = 0.001). Prone sleep positioning was still prevalent (32.2%) more so among Jews (35.2%) than Arabs (27%). CONCLUSION: Sleep positioning and overdressing do not appear to be the major attributable risk factors for UDI among Arab infants as compared to Jews. The compliance with positioning recommendations is lower than expected in both ethnic groups.

Arabs↗

American College of Cardiology/ European Society of Cardiology international study of angiographic data compression phase II. The effects of varying JPEG data compression levels on the quantitative assessment of the degree of stenosis in digital coronary angiography.

OBJECTIVES: This report describes whether lossy Joint Photographic Experts Group (JPEG) image compression/decompression has an effect on the quantitative assessment of vessel sizes by state-of-the-art quantitative coronary arteriography (QCA). BACKGROUND: The Digital Imaging and Communications in Medicine (DICOM) digital exchange standard for angiocardiography prescribes that images must be stored loss free, thereby limiting JPEG compression to a maximum ratio of 2:1. For practical purposes it would be desirable to increase the compression ratio (CR), which would lead to lossy image compression. METHODS: A series of 48 obstructed coronary segments were compressed/decompressed at CR 1:1 (uncompressed), 6:1, 10:1 and 16:1 and analyzed blindly and in random order using the QCA-CMS analytical software. Similar catheter and vessel start- and end-points were used within each image quartet, respectively. All measurements were repeated after several weeks using newly selected start- and end-points. Three different sub-analyses were carried out: the intra-observer, fixed inter-compression and variable inter-compression analyses, with increasing potential error sources, respectively. RESULTS: The intra-observer analysis showed significant systematic and random errors in the calibration factor at JPEG CR 10:1. The fixed inter-compression analysis demonstrated systematic errors in the calibration factor and recalculated vessel parameter results at CR 16:1 and for the random errors at CR 10:1 and 16:1. The variable inter-compression analysis presented systematic and random errors in the calibration factor and recalculated parameter results at CR 10:1 and 16:1. Any negative effect at CR 6:1 was found only for the calibration factor of the variable inter-compression analysis, which did not show up in the final vessel measurements. CONCLUSIONS: Compression ratios of 10:1 and 16:1 affected the QCA results negatively and therefore should not be used in clinical research studies.

Cardiology↗

American College of Cardiology/ European Society of Cardiology international study of angiographic data compression phase III. Measurement Of image quality differences at varying levels of data compression.

OBJECTIVES: We sought to investigate up to which level of Joint Photographic Experts Group (JPEG) data compression the perceived image quality and the detection of diagnostic features remain equivalent to the quality and detectability found in uncompressed coronary angiograms. BACKGROUND: Digital coronary angiograms represent an enormous amount of data and therefore require costly computerized communication and archiving systems. Earlier studies on the viability of medical image compression were not fully conclusive. METHODS: Twenty-one raters evaluated sets of 91 cine runs. Uncompressed and compressed versions of the images were presented side by side on one monitor, and image quality differences were assessed on a scale featuring six scores. In addition, the raters had to detect pre-defined clinical features. Compression ratios (CR) were 6:1, 10:1 and 16:1. Statistical evaluation was based on descriptive statistics and on the equivalence t -test. Results At the lowest CR (CR 6:1), there was already a small (15%) increase in assigning the aesthetic quality score indicating "quality difference is barely discernible-the images are equivalent.' At CR 10:1 and CR 16:1, close to 10% and 55%, respectively, of the compressed images were rated to be "clearly degraded, but still adequate for clinical use' or worse. Concerning diagnostic features, at CR 10:1 and CR 16:1 the error rate was 9.6% and 13.1%, respectively, compared with 9% for the baseline error rate in uncompressed images. CONCLUSIONS: Compression at CR 6:1 provides equivalence with the original cine runs. If CR 16:1 were used, one would have to tolerate a significant increase in the diagnostic error rate over the baseline error rate. At CR 10:1, intermediate results were obtained.

Adult↗

Common and epithelioid variants of hepatic angiomyolipoma exhibit clonal growth and share a distinctive immunophenotype.

Angiomyolipoma represents a rare liver tumor of uncertain histogenesis that is commonly considered a hamartoma. A series of 12 hepatic angiomyolipomas, including 3 samples of the epithelioid subtype, was analyzed for clonality using the human androgen receptor gene locus (HUMARA). Four of 6 informative cases revealed monoclonality. The polyclonal pattern in the 2 remaining cases was most probably caused by excessive infiltration of inflammatory cells. Monoclonality with an identical X-chromosomal inactivation pattern in all nodules was found in a multifocal recurrent tumor indicating a metastatic process. Despite the morphologic heterogeneity, all tumors displayed an identical immunohistochemical labeling pattern. It is concluded that different subtypes of hepatic angiomyolipoma exhibit a monoclonal and hence probably neoplastic growth and share an identical immunophenotype suitable for their identification even in small biopsy specimens. The epithelioid subtype may give rise to intrahepatic metastasis.

Adult↗

[The role of diffuse axonal injury in psychiatric assessment of brain-head trauma].

The concept of diffuse axonal injury is presented and the relevance in medicolegal assessment of brain injured patients is discussed. The lesion pattern of diffuse axonal injury not only plays a significant role in the acute management and rehabilitation of brain injured patients but also in issues of litigation. Brain imaging techniques are most important in the evaluation of structural damage to the brain and play a pivotal role in the detection of diffuse axonal injury. While computer-tomography follow-up studies may be valuable for the detection of diffuse axonal injury, magnetic resonance imaging is superior due to better sensitivity and contrast-resolution. The article presents selected case studies and illustrates the different lesion patterns.

Axons↗

Introducing residents to a career in management: the Physician Management Pathway.

To prepare their students and residents for the practice of medicine in a rapidly changing environment, medical educators must teach the business of medicine as well as the science and art of medicine. Recognizing the value of and demand for physician leaders, the authors sought to introduce residents to diverse aspects of medical administration within the context of an academically rigorous internal medicine residency program. The Physician Management Pathway (PMP) was developed in 1997 to expose interested residents to the management concepts employed by physician managers; to help physician trainees begin to develop the leadership and technical skills they will use as physician managers; to provide career mentoring; to provide experiences that enrich the resident's training in clinical medicine; to enhance resident-directed educational activities; and to produce physicians who can successfully work in any health care environment. The PMP curriculum consists of a monthly seminar series, a preceptorship experience in the second year of residency, and a supervised project in the third year. The program was not designed to provide competency in management, but rather is intended to provide an opportunity for new physicians to explore options in this exciting and changing profession.

Curriculum↗

Return visits to the emergency room after minor trauma from motor vehicle accidents.

Most patients with minor trauma following motor vehicle accidents (MVAs) are discharged from the emergency room (ER) of a trauma centre after evaluation and observation. Some return with similar or additional symptoms. This study aimed to determine which patients returned, if any injuries had been missed, and what should be the policy of medical management. We reviewed the records of 8836 patients with minor trauma following MVAs who were examined in an inner city trauma centre during 1997. When the group of patients who returned to the emergency room (n = 160) was compared with the whole post-MVA minor trauma group, the former was found to have more males (75.6% vs. 55.9%), younger age (36.31 years vs. 39.72 years), more motorcyclists than drivers, passengers and pedestrians ( p < 0.002, for the three variables), and had more multi-site injures. During the return visits the patients stayed longer in the emergency room, were examined by more consultants and had repeated radiological evaluations and tests, compared with the initial visit. However, in none of the patients was the initial diagnosis revised nor were additional injuries found and consequently the initial management was not changed in any of them. It is concluded that the initial thorough evaluation by the primary traumatologist is adequate for MVA patients with minor trauma. These patients do not require any follow up in specialized clinics, and are best managed in the community by their general practitioners.

Accidents, Traffic↗

Rudolf Karl Freudenberg - from pioneer of insulin treatment to pioneering social psychiatrist.

Rudolf Karl Freudenberg was Physician Superintendent at Netherne Hospital, Couldsdon, Surrey from 1951 to 1973. In his work as superintendent and government adviser he made important contributions to mental hospital reform and to the establishment of community psychiatric services in Britain. Earlier, in Vienna and following emigration to Britain, he was one of the pioneers of insulin coma treatment with a series of publications on this topic. The paper gives an account of published papers of both phases, and it highlights the background to Freudenberg's shift in professional interest from physical to social intervention. It argues that the change of emphasis reflects important general trends, i.e. profound change due to new forms of physical treatment on the one hand and similarly convincing evidence of the impact of social factors on clinical course and outcome on the other hand.

Austria↗