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  • Keywords: Jugular foramen; meningioma; carotid ligation; cerebral revascularisation  (1)
  • Lingula unguis  (1)
  • Metal-binding protein  (1)
  • 1
    ISSN: 0942-0940
    Keywords: Keywords: Jugular foramen; meningioma; carotid ligation; cerebral revascularisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two cases with huge dumbbell type jugular foramen meningioma with extension into the parapharyngeal space are reported. A well co-ordinated surgical strategy for total resection to this high risk tumour with neurosurgeons, otolaryngologists and plastic surgeons is mandatory to minimise operative complications. Both of our patients presented with a cervical mass and lower cranial nerve palsies, and had huge dumbbell type masses extending from the posterior cranial fossa through the jugular foramen to the parapharyngeal space, encasing the cervical internal carotid artery. Gross total resection of the tumours was successfully achieved by basically a 2-stage operation. In the first stage, posterior fossa tumours were removed by the transjugular approach, combined with the petrosal approach in one case. In the second stage, cervical tumours were removed along with the cervical carotid artery by the transcervical and/or transmandibular approach, followed by vascular reconstruction from the ipsilateral carotid artery to the middle cerebral artery using saphenous vein graft. From these experiences, we recommend this 2-stage operation for large dumbbell type meningiomas extending to the infratemporal/parapharyngeal space. The intracranial tumour is removed at the first operation. The extracranial portion is resected at the second, and if necessary, the involved cervical carotid artery is resected and simultaneous revascularisation using saphenous vein graft is performed with a vascularised free muscle graft. This strategy could maximise the functional preservation on the one hand, and minimise the surgical risk, such as postoperative infection, on the other.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1017
    Keywords: Hemerythrin ; Oxygenation ; Lingula unguis ; Stopped-flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract O2-jump experiments with an improved stopped-flow apparatus have been used to study oxygenation and deoxygenation processes in Lingula unguis hemerythrin. With an O2 electrode set in the observation cell, O2 concentration conld be obtained directly. The reliability of this method has been compared with other conventional methods. O2-jump (up and down) experiments were carried out with L. unguis hemerythrin at pH 6.8 (non-cooperative pH) and at pH 7.6 (cooperative pH). At pH 6.8, both O2-jump (up) and O2-jump (down) experiments showed single exponential processes which were consistent with the following scheme: $${\text{Hr + O}}_{\text{2}} \mathop \rightleftharpoons \limits_{{\text{k}}_{{\text{off}}} }^{{\text{k}}_{{\text{on}}} } {\text{HrO}}_{\text{2}} $$ . The value of k on was estimated to be (4.4 ± 0.5) × 105 M−1 s −1, and k off was (15 ± 5) s−1. These values are consistent with those obtained by the temperature-jump method (Zimmer et al. 1986). At pH 7.6, O2-jump (up) experiments showed two relaxation processes, whereas O2-jump (down) experiments showed a single exponential process. The faster process in the O2-jump (up) experiments could be attributed to the same process as that seen in the temperature-jump experiments (Zimmer et al. 1986). The slower process in the O2-jump (up) experiments corresponds to the process obtained in the O2-jump (down) experiments. The results are discussed in terms of a state with intermediate affinity in O2-binding and with the possible existence of a slow step in O2-binding.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1017
    Keywords: Transferrin ; Metal-binding protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The kinetics of binding of Cu (II), Tb (III) and Fe(III) to ovotransferrin have been investigated using the stopped-flow technique. Rate constants for the second-order reaction, k +, were determined by monitoring the absorbance change upon formation of the metal-transferrin complex in time range of milliseconds to seconds. The N and C sites appeared to bind a particular metal ion with the same rate; thus, average formation rate constants k + (average) were 2.4 × 104 M−1 s−1 and 8.3 × 104 M−1 S −1 for Cu (II) and Tb (III) respectively. Site preference (N site for Cu (II) and C site for Tb (III)) is then mainly due to the difference in dissociation rate constant for the metals. Fe (III) binding from Fe-nitrilotriacetate complex to apo-ovotransferrin was found to be more rapid, giving an average formation rate constant k + (average) of 5 × 105 M−1 s−1, which was followed by a slow increase in absorbance at 465 nm. This slow process has an apparent rate constant in the range 3 s−1 to 0.5 s−1, depending upon the degree of Fe (III) saturation. The variation in the rate of the second phase is thought to reflect the difference in the rate of a conformational change for monoferric and diferric ovotransferrins. Monoferric ovotransferrin changes its conformation more rapidly (3.4s−1) than diferric ovotransferrin (0.52 s−1). A further absorbance decrease was observed over a period of several minutes; this could be assigned to release of NTA from the complex, as suggested by Honda et al. (1980).
    Type of Medium: Electronic Resource
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