| 1. |
- Englund, E., et al.
(författare)
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Tumours of the central nervous system. Proton magnetic resonance relaxation times T1 and T2 and histopathologic correlates
- 1986
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Ingår i: Acta Radiologica Diagnosis. - : SAGE Publications. - 0567-8056. ; 27:6, s. 653-659
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Tidskriftsartikel (refereegranskat)abstract
- Proton MR relaxation times T1 and T2 were determined in vitro in 136 small specimens of astrocytomas grades I-IV, of oligodendrogliomas, metastases of adenocarcinomas, meningiomas and acoustic neuromas. In addition, 7 samples of peritumoural white matter were analysed. The analysed specimens were studied microscopically in their entirety regarding tumour type and occurrence of necrosis and non-tumour tissue admixture, such as fibrosis and haemorrhage. Most of the gliomas had longer relaxation times than normal white matter and T2 was significantly longer than in the other three tumour groups. The metastases had longer T1 than normal white matter, while T2 varied. The astrocytomas tended to show shorter relaxation times with increasing degree of malignancy, and shortening of T1 and T2 correlating with the proportion of tissue necrosis. Similarly, the metastases with tissue necrosis had shorter T1 and T2 than non-necrotic samples. The meningiomas had T1 values comparable with normal cortex, while the T2 values varied. Tumours containing a large proportion of fibrous tissue had shorter relaxation times than the others. Acoustic neuromas had only slightly longer T1 than normal white matter, while T2 was not prolonged. Both T1 and T2 were significantly shorter than in all other tumours studied. Peritumoural white matter had prolonged relaxation times compared with normal white matter, correlating to increased water content. These in vitro differences regarding relaxation times in various types of tumours of the central nervous system, dependent on various types of tissue alterations, should be of interest for the interpretation of in vivo images.
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| 2. |
- Györffy-Wagner, Z., et al.
(författare)
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Proton magnetic resonance relaxation times T1 and T2 related to postmortem interval : An Investigation on Porcine Brain Tissue
- 1986
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 0567-8056. ; 27:1, s. 115-118
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Forskningsöversikt (refereegranskat)abstract
- In order to establish the validity of in vitro determination of the proton magnetic resonance (MR) relaxation times T1 and T2 in brain tissue at increasing time delay after death or operative excision, 81 brain tissue samples from 23 pigs were analyzed repeatedly. These samples, representing cortex, caudate nucleus and white matter, were studied microscopically after MR measurements. The T1 values exhibited no time dependence and the T2 values decreased slightly during the interval 2 to 90 hours after death. The samples were stored at +8°C between the measurements. These results indicate that reliable in vitro measurements can be obtained in autopsy or surgical brain tissue specimens within 90 hours after death or excision, if handled properly.
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| 3. |
- Larsson, E. M., et al.
(författare)
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Regional differences in the proton magnetic resonance relaxation times T1 and T2 within the normal human brain
- 1986
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 0567-8056. ; 27:2, s. 231-234
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Forskningsöversikt (refereegranskat)abstract
- The proton magnetic resonance (MR) relaxation times T1 and T2 were determined in autopsy specimens from 13 different regions of normal human brains. One hundred and seventy-four tissue samples from 25 brains were examined in a pulsed MR analyzer of 0.25 T and were then also studied histologically. There were regional differences in T1 and T2 within the cerebral gray matter but not within the white matter. These regional differences might reflect the different composition and cytoarchitectonic structure of the cortical regions and should be taken into consideration in the interpretation of cortical lesions on MR images.
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| 4. |
- Reutersward, A, et al.
(författare)
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Variations in binding of mammalian fibrinogens to streptococci groups A, B, C, E, G and to Staphylococcus aureus
- 1985
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Ingår i: Acta pathologica, microbiologica, et immunologica Scandinavica. Section B, Microbiology. - 0108-0180. ; 93:2, s. 77-82
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Tidskriftsartikel (refereegranskat)abstract
- Twenty-eight beta-hemolytic streptococci of groups A, B, E, G and Streptococcus equisimilis as well as four Staphylococcus aureus strains were tested for their ability to bind fibrinogen preparations from different animal species: homo, baboon, rabbit, rat, guinea-pig, dog, horse, pig, cow and sheep. The patterns of binding indicated differences in the structures of the bacterial fibrinogen receptors. There were higher binding levels in streptococci groups A, G, and S. equisimilis than in representative group B and E strains. Considerable differences in the binding capacity were found within streptococci groups A and E. Group C and group G strains showed rather similar patterns and could be further divided into high-level and low-level binding strains. There is no correlation between binding levels of different animal fibrinogen preparations and the strains isolated from corresponding animals. Recent studies by others have shown that resistance to phagocytosis is mediated by fibrinogen-binding in streptococci group A. The existence of similar fibrinogen-binding structures in several streptococcal species indicates an important role with a definite survival value. It also suggests that M or T protein analogues are present in streptococci groups C, G and E.
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