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Air bags: some myths dispelled 总被引:1,自引:0,他引:1
J D States 《The Journal of trauma》1972,12(2):178-179
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Acquired pendular nystagmus: its characteristics, localising value and pathophysiology 总被引:5,自引:4,他引:1
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Investigations were made of 16 patients with acquired pendular nystagmus and a further 32 cases reported in the literature were reviewed. Amongst our own patients two thirds had multiple sclerosis, almost one third a cerebrovascular accident or angioma and two had optic atrophy with squint. The nystagmus took forms which could be monocular or binocular, conjugate or disconjugate and could involve movements about single or multiple axes. Spectral analysis was used to characterise the amplitude and frequency of the movements and to estimate the degree of relationship (coherence) between movements of the two eyes or between movements of one eye about several axes. The oscillations ranged in frequency from 2·5 Hz to 6 Hz, with typical amplitudes between 3° and 5°. In a given patient all oscillations, regardless of plane, were highly synchronised. Somatic tremors of the upper limb, face and palate associated with the nystagmus were often at similar frequencies to the eye movement. The other ocular signs common to all our patients were the presence of squint with failure of convergence. Most patients also had skew deviation or internuclear ophthalmoplegia or both. The major oculomotor systems, that is, saccades, pursuit, optokinetic and vestibulo-ocular reflexes could be intact. It is inferred that the mechanism responsible for the pendular nystagmus lies at a level which is close to the oculomotor nuclei so that it can have monocular effects but is not part of the primary motor pathways. It is possible that this mechanism normally subserves maintenance of conjugate movement and posture of the eyes. The periodicity of the nystagmus is likely to arise from instability in a certain type(s) of neurone, for the associated somatic tremors have similar characteristics and yet involve very different neuronal muscular circuitry. Prognosis for cessation of the nystagmus is poor. In five patients with multiple sclerosis it was suppressed by intravenous hyoscine with, however, unacceptable subsequent side effects. 相似文献
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Understanding diet and energy balance as risk factors for breast, colon,
and other cancers requires information on the contribution of each factor
and of interactions among factors to cancer risk. Rodent models for breast
cancer provide extensive data on effects of dietary fat and calories,
energy balance, body weight gain, and physical activity on tumor
development. Analyses of the combined data from many studies have shown
clearly that quality and quantity of dietary fat and energy balance
contribute independently to increased mammary gland tumorigenesis. These
findings were seen in female rats fed diets high in fat (35-40% of
calories) compared to rats fed control diets, with approximately 10% of
calories as fat (Fay and Freedman, 1997, Breast Cancer Res. Treat. 46,
215-223). The methods used permit comparison of experimental and
epidemiological data, and they may be useful in extrapolating between
species and developing public health recommendations. In addition to the
contributions of lifetime-diet composition, intake, energy balance, and
physical activity to cancer risk, there are questions about the timing and
duration of alterations in these factors and about the "dose-response"
characteristics of cancer risk to the factors. Endocrine mechanisms may be
significant in mammary gland tumor risk, but experimental and
epidemiological data indicate that cancers at other sites, such as colon
and liver, also are influenced by the factors listed. Other diet and
lifestyle factors that influence energy, or specifically fat, metabolism
may also affect risk for cancers that are promoted by increased intake of
fat and calories. Studies of separate and interactive effects of dietary
fat, black tea, weight gain, and mammary gland tumorigenesis (Rogers, et
al, 1998, Carcinogenesis 19, 1269-1273) have been analyzed. Using
adjustment of carcinogenesis endpoints for body weight, tumor burden, and
latency, they were found to be related to weight gain within treatment
groups in 2 of 3 experiments.
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