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  • 1
    Electronic Resource
    Electronic Resource
    Vinyltrimethylsilane-co-N-vinyl-2-pyrrolidone and vinyltrimethoxysilane-co-N-vinyl-2-pyrrolidone copolymers Synthesis and reactivity ratios (1998)
    Springer
    Polymer bulletin 40 (1998), S. 707-713 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Copolymers containing vinyltrimethylsilane and vinyltrimethoxysilane with N-vinyl-2-pyrrolidone at different compositions were synthesized and characterized. The reactivity ratios was estimated by using the classical Fineman-Ross and Kelen Tüdos linear fitting procedures. These parameters were also estimated through a computer program based on nonlinear minimization algorithm, starting from the r1 and r2 values obtained by the former procedures. The analysis of the results allow us to interpret the reactivity behaviour of these polymers in terms of the relative reactivity of the substiuents. The effect of the chemical structure of the polymer side group is discussed in terms of the different contributions to the stabilization of the radical intermediates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002890050312
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  • 2
    Electronic Resource
    Electronic Resource
    Cerebral cortex blood flow and vascular smooth muscle contractility in a rat model of ischemia: a correlative laser Doppler flowmetric and scanning electron microscopic study (1997)
    Springer
    Acta neuropathologica 93 (1997), S. 354-368 
    Details
    ISSN: 1432-0533
    Keywords: Key words Reperfusion ; Cerebral blood flow ; Vascular smooth muscle cell ; Pericyte ; Scanning ; electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present study was undertaken to ascertain the role of smooth muscles and pericytes in the microcirculation during hyperperfusion and hypoperfusion following ischemia in rats. Paired external carotids, the pterygopalatine branch of the internal carotids and the basilar artery were exposed and divided. Reversible inflatable occluders were placed around the common carotids. After 24 h, the unanesthetized rat underwent 10-min ischemia by inflating the occluders. Continuous cortical cerebral blood flow (c-CBF) was monitored by laser Doppler flowmetry. The measured c-CBF was below 20% of control (P 〈 0.001) during ischemia. A c-CBF of 227.5 ± 54.1% (P 〈 0.001) was obtained during reperfusion hyperemia. A c-CBF of 59.7 ± 8.8% (P 〈 0.001) occurred at the nadir of postischemic hypoperfusion, and this was followed by a second hyperemia. The cytoarchitecture of the vascular smooth muscles and pericytes was assessed by scanning electron microscopy. Samples were prepared using a KOH-collagenase digestion method. In control rats, arteriolar muscle cells showed smooth surfaces. Capillary pericytes were closely apposed to the endothelium. Immediately after reperfusion, transverse membrane creases were observed on the smooth muscle surfaces. During maximal hyperemia the creases disappeared. When c-CBF started to decrease the creases became visible again. Throughout the postischemic hypoperfusion the creases remained. Capillary endothelial walls became tortuous in the late phase of hypoperfusion. During the second hyperemia most arteriolar muscle cells showed smooth surfaces. Some pericytes appeared to have migrated from the vascular wall. The morphological changes of smooth muscle membranes suggest that they are related to specific perfusional disturbances during ischemia and reperfusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050627
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  • 3
    Electronic Resource
    Electronic Resource
    Radiosurgery for Cerebral Arteriovenous Malformations (1998)
    Springer
    Journal of radiosurgery 1 (1998), S. 225-231 
    Details
    ISSN: 1573-8752
    Keywords: Arteriovenous malformation ; γ knife ; LINAC ; radiosurgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract From September 1991 to May 1997, a total of 59 patients diagnosed with cerebral arteriovenous malformations were treated using radiosurgery. There were 29 men and 30 women, with an age range of 5 to 75 years (mean 36). Of these patients, 39 patients were treated using a LINAC-based system (group 1) and 20 using the Leksell γ-knife unit (group 2). Tumor volume ranged from 0.38 to 35 cc, and the number of isocenters varied from 1 to 3 in group 1 and from 2 to 15 in group 2. Lesion location was as follows: 14 temporal, 8 basal ganglionic, 8 frontal, 6 parietal, 6 thalamic, 5 intraventricular, 5 cerebellar, 3 brain stem, 3 occipital, and 1 corpus callosal. Seven patients underwent prior embolization and three patients had prior surgery with incomplete resection of their lesions. The marginal radiation dose ranged between 1500 and 2000 cGy with a mean of 1800 cGy. Twelve patients had concomitant embolization done on the morning of radiosurgery. Follow-up ranged from 1 month to 4 years. Thirty-six patients have been followed for more than 1 year. Thirty had an angiography during the follow-up period that showed complete obliteration of the lesion in 28 patients. The rate of obliteration was estimated to be 47.1% at 1 year, 82.3% at 2 years and 88.2% at 3 years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/B:JORA.0000015198.05410.96
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  • 4
    Electronic Resource
    Electronic Resource
    γ-Knife Radiosurgery for Brainstem Lesions: The Wayne State University Experience (1999)
    Springer
    Journal of radiosurgery 2 (1999), S. 135-139 
    Details
    ISSN: 1573-8752
    Keywords: Brainstem ; stereotactic radiosurgery ; γ-knife ; performance status
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Stereotactic radiosurgery (SRS) is increasingly being used for tumors of the brainstem because it suits the anatomical constraints of this area. We now report on the 2-year experience at Wayne State University using γ-knife SRS for such lesions, with an emphasis on toxicity and morbidity. From January 1996 to January 1998, sixteen patients (6 males and 10 females) with lesions in the area of the brainstem were treated with SRS. Average age was 53 years (range 19–80). Nine lesions were malignant; 7 were benign. Median Karnofsky performance status (KPS) prior to SRS was 80 (range 50–100). Median follow-up period from initial diagnosis to analysis, and from the date of SRS to analysis, was 24 months (range 11–73) and 15 months (range 4–29), respectively. Results were analyzed for the whole population treated and then stratified by diagnosis: benign versus malignant. At analysis, 10 (62.6%) patients were alive and 6 (37.5%) were dead. No deaths followed SRS. Values for KPS prior to SRS were compared to 3 months post-SRS. No significant change in KPS scores could be observed for those with benign lesions, but 67% of patients with malignant tumors showed a KPS drop ≥30 points. There was no correlation between the treated volume and survival. At the time of review, no patients had developed new neurological symptoms after SRS. Results for benign lesions indicate that SRS is well tolerated, provides good local control, and does not cause unusual rates of morbidity or mortality. Results for malignant lesions demonstrate that pretreatment performance status influences the post-SRS values. The post-SRS Median Survival (MS) of 10 months for the Malignant Lesions (M) is impressive, in light of the drop of KPS observed; the outcome for such patients is likely determined by the activity of the primary disease process. Our results suggest that SRS in the brainstem is safe, feasible, and merits further study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022966629467
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  • 5
    Electronic Resource
    Electronic Resource
    Genetic analysis of the relationships between behavioral and neuroendocrine traits in roman high and low avoidance rat lines (1995)
    Springer
    Behavior genetics 25 (1995), S. 371-384 
    Details
    ISSN: 1573-3297
    Keywords: Roman rat lines ; adrenal hormones ; prolactin ; avoidance behavior ; tyrosine hydroxylase and phenylethanolamineN-methyl transferase activities ; segregating crosses ; multivariate analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract In order to determine whether the coselection observed between the selection trait (active avoidance behavior) of the Roman High Avoidance (RHA) and Roman Low Avoidance (RLA) rat lines and their neuroendocrine characteristics were genetically determined, we analyzed, in nonsegregating (RHA, RLA, and F1) and segregating (F2 and the two backcrosses) crosses, the inheritance pattern and the phenotypic correlations among behavioral (shuttle-box behavior), physiological (body, adrenal, and thymus weights), and neuroendocrine (corticosterone and prolactin reactivity, catecholamine enzyme activities) variables. Physiological characteristics and enzyme activities have acrucial role in sex dissociation. Avoidance behavior and prolactin reactivity to novel environment remained associated in segregating crosses despite gene rearrangement. They represented the most important variables to differentiate the Roman lines, perhaps sharing a common regulatory mechanism under genetic control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02197288
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  • 6
    Electronic Resource
    Electronic Resource
    Vocalizations in newborn mice: Genetic analysis (1996)
    Springer
    Behavior genetics 26 (1996), S. 427-437 
    Details
    ISSN: 1573-3297
    Keywords: Vocalizations ; ultrasounds ; development ; newborn ; mice ; NZB/BINJ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Two kinds of vocalizations are produced by newborn mice: whistles (between 50 and 150 ms in length), having a narrow bandwidth in each strain that ranges from 30 to 90 kHz; and clicks, which are shorter (about 1 ms) and have a larger bandwidth. These vocalizations were individually recorded in 1-day-old pups from seven inbred strains of laboratory mice, at two temperatures (23±0.5 and 15±0.5°C). The numbers of clicks and whistles were counted under these two conditions. Moreover, the length and frequencies at the beginning, apex, and end of the whistles were measured during the 15°C condition. Correlations, including several components—additivity, epistasis (between homozygous loci), and maternal environment—were calculated between the characteristics of the whistles during the 15°C condition. Clicks and whistles were also counted from 1 to 8 days of age during the 15°C condition. The numbers of clicks and whistles were age dependent, with a decrease from day 1 to day 8 for the clicks and a consistent production of whistles. A quantitative genetic analysis was also performed on the 1-day-old pups from the mendelian generations produced by the inbred strains most contrasting for the number of whistles produced in the cold condition: NZB/BINJ and CBA/H. The heterozygous genotype of the mother induced an increment of the number of whistles. Moreover, a significant part of the additive variance was suspected from the first design, and found with the second one, for this variable. Quantitative genetic analysis showed significant dominance and epistasis between homozygous loci and homozygous and heterozygous loci. This points to multigenic correlates for the number of whistles in this population. The significant additive values for all the variables recorded during the 15±0.5°C condition and for the number of whistles produced during the 23±0.5°C condition are compatible with an effect the indicates neither directional nor stabilizing selection. This results is examined in the light of the multichannel sensorial process implicated in maternal behavior in mice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02359487
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