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  • Photoreceptor  (2)
  • Spine  (2)
  • 77 K fluorescence  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European spine journal 6 (1997), S. 33-38 
    ISSN: 1432-0932
    Keywords: Familial dysautonomia ; Spine ; Spine fusion ; Scoliosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Familial dysautonomia (FD) is a rare autosomal recessive disease occurring in Jews of Ashkenazi descent, with only some 500 recognized cases. The causative gene was identified on chromosome 9. FD is of considerable orthopedic interest, because of the prevalence of skeletal deformity. About 90% of surviving dysautonomic children will develop a spinal curvature, commonly a scoliliotis. The scoliotic curve is usually kyphotic rather than lordotic, and appears during the first decade of life. Fifty-one of the 90 reported cases of familial dysautonomia in Israel involved patients who were seen at the scoliliotis clinic for assessment and treatment of their spinal deformities. Most of the patients presented with a scoliotic deformity associated in 37 cases with an increased thoracic kyphosis. In our series orthotic treatment and physiotherapy were found to be minimally successful at best. Surgical treatment of the spine was performed in 13 of 51 patients in this series. A retrospective review of these patients' charts and radiographs was carried out. Six years of follow-up are reported. The primary indication for surgery was progression of the spinal curve. Only posterior spinal fusions were performed. Anterior transthoracic procedures were avoided in spite of the significance of the kyphotic deformity, because of the frequency of pulmonary complications. Harrington distraction and compression instrumentation was used. Three-millimeter compression rods were used in a distraction mode in thin, young children. “Harri-Luque” segmental sublaminar wiring technique and Wisconsin spinous process segmental wiring was used in some. In all cases, the spine fusion was supplemented by bank bone only, to avoid the additional trauma of graft removal. We believe that surgical intervention is advantageous, if done early in the evolution of spinal deformity. Greater technical difficulties and a higher complication rate were encountered in this series relative to the problems usually seen after spinal deformity surgery in children; this is all the more important in a disease in which general anesthesia is an additional major complicating factor. It is hoped that the improved physical condition now seen after early gastrostomy and fundoplication will aid in reducing this high complication rate. Only a small degree (about 25%) of correction was achieved in the majority of patients. Some of this apparent rigidity derived from the inability to apply sufficient instrumental corrective force because of the friable osteoporotic bone. After surgery, there was a marked decrease in the frequency of pneumonia and an improvement in the degree of ataxia, for reasons not understood, which led to an obvious improvement in the quality of life.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0932
    Keywords: Key words Scoliosis ; surgery ; Spine ; Spinal fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Appropriate levels for instrumentation and fusion in scoliosis have been a matter of debate among surgeons since the introduction of operative management of this deformity. We set out to examine the hypothesis that the amount of correction achieved in all planes during surgical instrumentation of a curve should be less than, or comparable to, the degree of correction attainable at any non-instrumented adjacent curve. An algorithm was designed to facilitate preoperative planning and intraoperative performance of spinal fusion procedures in the management of scoliosis. To test the validity of the hypothesis and the proposed algorithm, measurements were taken from the preoperative radiographs of 200 patients. The dimensions of the curves were obtained from an initial set of four X-ray films: (1) standing anteroposterior film of the whole spine, (2) standing lateral film of the whole spine, (3) two properly performed side-bending films including each curve of the spine. With this data, a plan was designed using the algorithm. The results of this plan were compared with the actual results of the surgery, which were revealed only at this stage. All patients in whom actual instrumentation levels fell within those predicted by the proposed algorithm had no imbalance at follow-up. All patients whose actual instrumentation levels were short of those recommended by the algorithm showed obvious imbalance on final postoperative standing radiograph.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2048
    Keywords: Arabidopsis ; Blue light ; Photoreceptor ; Photosynthesis ; Photosystem stoichiometry ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The regulation by light of the composition of the photosynthetic apparatus was investigated in Arabidopsis thaliana (L.) Heynh. cv. Landsberg erecta. When grown in high- and low-irradiance white light, wild-type plants and photomorphogenic mutants showed large differences in their maximum photosynthetic rate and chlorophyll a/b ratios; such changes were abolished by growth in red light. Photosystem I (PSI) and PSII levels were measured in wild-type plants grown under a range of light environments; the results indicate that regulation of photosystem stoichiometry involves the specific detection of blue light. Supplementing red growth lights with low levels of blue light led to large increases in PSII content, while further increases in blue irradiance had the opposite effect; this latter response was abolished by the hy4 mutation, which affects certain events controlled by a blue-light receptor. Mutants defective in the phytochrome photoreceptors retained regulation of photosystem stoichiometry. We discuss the results in terms of two separate responses controlled by blue-light receptors: a blue-high-fluence response which controls photosystem stoichiometry; and a blue-low-fluence response necessary for activation of such control. Variation in the irradiance of the red growth light revealed that the blue-high-fluence response is attenuated by red light; this may be evidence that photosystem stoichiometry is controlled not only by photoreceptors, but also by photosynthetic metabolism.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2048
    Keywords: Key words: Acclimation ; Arabidopsis (acclimation) ; Chloroplast ; Photomorphogenesis ; Photoreceptor ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The regulation by light of the composition of the photosynthetic apparatus was investigated in photomorphogenic mutants of Arabidopsis thaliana (L.) Heynh. cv. Landsberg erecta. Leaf chlorophyll, photosynthesis, photosystem II function, and ribulose-1,5-bisphosphate carboxylase-oxygenase and photosystem II contents were determined for plants grown under high- or low-irradiance growth regimes. Although certain mutant lines had altered chloroplast composition compared to the wild type, all photoreceptor mutants tested were capable of light-dependent changes in chloroplast composition and photosynthetic function, indicating that photoreceptors do not play a central role in the regulation of acclimation at the level of the chloroplast. However, the clear acclimation defect in a det1 signal transduction mutant indicates that photoreceptor-controlled responses either share regulatory components with acclimation, or are important in the expression of components which in turn regulate acclimation. We suggest that the COP/DET/FUS regulatory cluster is a focus for multiple signal transduction pathways, including some of the metabolic signals which form the basis for the acclimatory response.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Photosynthesis research 27 (1991), S. 121-133 
    ISSN: 1573-5079
    Keywords: high-energy state quenching ; photoinhibition ; photosynthesis ; state transition ; 77 K fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Non-photochemical chlorophyll fluorescence quenching (qN) in barley leaves has been analysed by monitoring its relaxation in the dark, by applying saturating pulses of light. At least three kinetically distinct phases to qN recovery are observed, which have previously been identified (Quick and Stitt 1989) as being due to high-energy state quenching (‘fast’), excitation energy redistribution due to a state transition (‘medium’) and photoinhibition (‘slow’). However, measurements of chlorophyll fluorescence at 77 K from leaf extracts show that state transitions only occur in low light conditions, whereas the ‘medium’ component of qN is very large in high light. The source of that part of the ‘medium’ component not accounted for by a state transition is discussed.
    Type of Medium: Electronic Resource
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