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81.
Losanoff JE Richman BW Jones JW 《Journal of the American College of Surgeons》2002,195(3):437-8; author reply 438
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Obturator hernia 总被引:2,自引:0,他引:2
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Maselli RA Kong DZ Bowe CM McDonald CM Ellis WG Agius MA Gomez CM Richman DP Wollmann RL 《Neurology》2001,57(2):279-289
OBJECTIVE: To provide clinical, electrophysiologic, and ultrastructural findings in three patients with a presynaptic congenital myasthenic syndrome (CMS). BACKGROUND: Familial infantile myasthenia and paucity of synaptic vesicles are the only two fully characterized CMS. We are describing here three patients with another form of presynaptic CMS characterized by deficiency of the action potential-dependent release without reduction of the spontaneous release of neurotransmitter from the nerve terminal. METHODS: The authors performed electromyography and anconeus muscle biopsies that included intracellular recordings and electron microscopy of the neuromuscular junction in three patients with presynaptic CMS. They also sequenced part of the P/Q-calcium alpha(1)-subunit gene (CACNA1A) and the acetylcholine receptor subunit (AChR) genes in these patients. RESULTS: In these patients there were additional neurologic findings including nystagmus and ataxia. In all three patients the end-plate potential quantal content (m) was markedly reduced but neither the amplitudes nor the frequencies of miniature end-plate potentials were diminished. Ultrastructurally, postsynaptic end-plate folds, nerve terminal size, and synaptic vesicle number were normal but double-membrane-bound sacs containing synaptic vesicles were present in the nerve terminal of all three patients. The screening of reported pathogenic mutations in the CACNA1A and a mutational analysis of AChR subunit genes were negative. CONCLUSION: This form of CMS appears to result only from a deficiency of the quantal release of neurotransmitter that may be due to an abnormal calcium mechanism or impaired endocytosis and recycling of synaptic vesicles. 相似文献
86.
A DNA endonuclease, isolated from the nuclei of normal human and xeroderma
pigmentosum complementation group A (XPA) cells, which recognizes
predominately pyrimidine dimers, was examined for the mechanism by which it
locates sites of damage on UVC-irradiated DNA. In reaction mixtures with
low ionic strengths (i.e. lacking KCl), the normal and XPA endonuclease
locate sites of UV damage on both naked and reconstituted nucleosomal DNA
by different mechanisms. On both of these substrates, the normal
endonuclease acts by a processive mechanism, meaning that it binds
non-specifically to DNA and scans the DNA for sites of damage, whereas the
XPA endonuclease acts by a distributive one, meaning that it randomly
locates sites of damage on DNA. However, while both the normal and XPA
endonucleases can incise UVC irradiated naked DNA, they differ in ability
to incise damaged nucleosomal DNA. The normal endonuclease showed increased
activity on UVC treated nucleosomal DNA compared with naked DNA, whereas
the XPA endonuclease showed decreased activity on the damaged nucleosomal
substrate. Since a processive mechanism of action is sensitive to the ionic
strength of the micro-environment, the KCl concentration of the reaction
was increased. At 70 mM KCI, the normal endonuclease switched to a
distributive mechanism of action and its ability to incise damaged
nucleosomal DNA also decreased. These studies show that there is a
correlation between the ability of these endonucleases to act by a
processive mechanism and their ability to incise damaged nucleosomal DNA;
the normal endonuclease, which acts processively, can incise damaged
nucleosomal DNA, whereas the XPA endonuclease, which acts distributively,
is defective in ability to incise this substrate.
相似文献
87.
We contrast Western medical views of chronic fatigue syndrome (CFS) etiology, diagnosis, and treatment with views maintained by a predominantly female CFS population. We argue that the failure of Western medicine to demonstrate a viral etiology for CFS led to a paradigmatic shift in research perspectives, which then embraced psychiatric and sociocultural explanations for CFS. As a result, CFS was delegitimized as a biomedical phenomenon within medical, academic, governmental, and public arenas. We compare alternative social constructions of CFS with issues pertaining to multiple sclerosis (MS), an illness that similarly predominates among women. Patient perspectives suggest that the history of medical attitudes toward CFS may eventually parallel the transformations that occurred in relation to MS. In particular, the discovery of biological markers for CFS may lay to rest the categorization of CFS as largely within the psychiatric realm. 相似文献
88.
NRM Buist AP Prince KL Huntington JM Tuerck DD Waggoner 《Acta paediatrica (Oslo, Norway : 1992)》1994,83(S407):75-77
A new amino acid mixture for incorporation into medical foods for the treatment of hyperphenylalaninemia has been tested in a regular clinic. The mix is designed to be as unobtrusive as possible, consistent with good nutrition. After more than 1 year of trial as a beverage, we have shown that it is safe and well tolerated but that plasma phenylalanine is no better controlled than with some other products. The mix can be incorporated into a large number of different foods without affecting the taste. Occult monitoring of the quantity of medical foods purchased compared with the amounts reported to be consumed in diet histories provides an excellent way to monitor dietary compliance. 相似文献
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