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991.
GE McClearn B Johansson S Berg NL Pedersen F Ahern SA Petrill R Plomin 《Canadian Metallurgical Quarterly》1997,276(5318):1560-1563
General and specific cognitive abilities were studied in intact Swedish same-sex twin pairs 80 or more years old for whom neither twin had major cognitive, sensory, or motor impairment. Resemblance for 110 identical twin pairs significantly exceeded resemblance for 130 fraternal same-sex twin pairs for all abilities. Maximum-likelihood model-fitting estimates of heritability were 62 percent for general cognitive ability, 55 percent for verbal ability, 32 percent for spatial ability, 62 percent for speed of processing, and 52 percent for memory. There was also evidence for the significant influence of idiosyncratic experience as the environmental component that most determines individual differences in cognitive abilities late in life. 相似文献
992.
F Duclos V Straub SA Moore DP Venzke RF Hrstka RH Crosbie M Durbeej CS Lebakken AJ Ettinger J van der Meulen KH Holt LE Lim JR Sanes BL Davidson JA Faulkner R Williamson KP Campbell 《Canadian Metallurgical Quarterly》1998,142(6):1461-1471
Limb-girdle muscular dystrophy type 2D (LGMD 2D) is an autosomal recessive disorder caused by mutations in the alpha-sarcoglycan gene. To determine how alpha-sarcoglycan deficiency leads to muscle fiber degeneration, we generated and analyzed alpha-sarcoglycan- deficient mice. Sgca-null mice developed progressive muscular dystrophy and, in contrast to other animal models for muscular dystrophy, showed ongoing muscle necrosis with age, a hallmark of the human disease. Sgca-null mice also revealed loss of sarcolemmal integrity, elevated serum levels of muscle enzymes, increased muscle masses, and changes in the generation of absolute force. Molecular analysis of Sgca-null mice demonstrated that the absence of alpha-sarcoglycan resulted in the complete loss of the sarcoglycan complex, sarcospan, and a disruption of alpha-dystroglycan association with membranes. In contrast, no change in the expression of epsilon-sarcoglycan (alpha-sarcoglycan homologue) was observed. Recombinant alpha-sarcoglycan adenovirus injection into Sgca-deficient muscles restored the sarcoglycan complex and sarcospan to the membrane. We propose that the sarcoglycan-sarcospan complex is requisite for stable association of alpha-dystroglycan with the sarcolemma. The Sgca-deficient mice will be a valuable model for elucidating the pathogenesis of sarcoglycan deficient limb-girdle muscular dystrophies and for the development of therapeutic strategies for this disease. 相似文献
993.
Diffuse well differentiated papillary mesothelioma is a rare neoplasms of the peritoneal cavity which has generally been regarded as a tumor with low-grade malignant potential [1-4]. The well differentiated papillary mesotheliomas reported in recent literature are considered as border line lesions with a long term benign clinical course. There are however, only few studies with small numbers of diffuse well differentiated mesotheliomas [1, 2, 5, 6]. The synchronous appearance of such a lesion with a second malignancy therefore is a very rare event. Such a clinical scenario would suggest diffuse tumor spread to the peritoneum resulting in an inappropriate palliative procedure alone-being undertaken. To our knowledge this is the first report of the simultaneous occurrence of a rectal carcinoma in combination with a diffuse well differentiated papillary mesothelioma of the peritoneum. 相似文献
994.
Transgenic NOD backcross mice expressing pancreatic interleukin 10 (IL-10) were crossed and backcrossed to NOD.B6 Idd3 Idd10 mice, which have diabetes-resistance alleles at Idd3 and Idd10 on chromosome 3 and have a very low frequency diabetes and insulitis. Insulitis and diabetes developed in almost all IL-10 transgenic backcross 1 (BC1) mice of the H2g(7/g7) haplotype regardless of the allelic status at Idd3 and Idd10. Furthermore, diabetes occurred in 23% of IL-10 transgenic H2g(7/d) BC1 mice. These results indicate that pancreatic IL-10 is able to overcome the diabetes protection afforded by C57BL/6 (B6)-derived alleles at Idd3 and Idd10 as well as the absence of NOD MHC homozygosity, if other non-MHC NOD-derived Idd alleles are provided. 相似文献
995.
996.
HS Chen JW Pellegrini SK Aggarwal SZ Lei S Warach FE Jensen SA Lipton 《Canadian Metallurgical Quarterly》1992,12(11):4427-4436
Excessive activation of NMDA receptors is thought to mediate the calcium-dependent neurotoxicity associated with hypoxic-ischemic brain injury, trauma, epilepsy, and several neurodegenerative diseases. For this reason, various NMDA antagonists have been investigated for their therapeutic potential in these diseases, but heretofore none have proven to be both effective and safe. In the present study, memantine, an adamantane derivative similar to the antiviral drug amantadine, is shown to block the channels activated by NMDA receptor stimulation. From whole-cell and single-channel recording experiments, the mechanism of action of memantine is deduced to be open-channel block, similar to MK-801; however, unlike MK-801, memantine is well tolerated clinically. Compared to MK-801, memantine's safety may be related to its faster kinetics of action with rapid blocking and unblocking rates at low micromolar concentrations. Furthermore, at these levels memantine is an uncompetitive antagonist and should theoretically allow near-normal physiological NMDA activity throughout the brain even in the face of pathologically high focal concentrations of glutamate. These pharmacological properties confer upon memantine a therapeutic advantage against NMDA receptor-mediated neurotoxicity with few side effects compared with other organic NMDA open-channel blockers. Moreover, memantine is increasingly effective against escalating levels of glutamate, such as those observed during a stroke. Low micromolar concentrations of memantine, levels known to be tolerated by patients receiving the drug for the treatment of Parkinson's disease, prevent NMDA receptor-mediated neurotoxicity in cultures of rat cortical and retinal ganglion cell neurons; memantine also appears to be both safe and effective in a rat stroke model. These results suggest that memantine has considerable therapeutic potential for the myriad of clinical entities associated with NMDA receptor-mediated neurotoxicity. 相似文献
997.
998.
999.
Several lines of clinical evidence suggest that myoclonus is caused by a reduction of serotonin in the brain and hyperactivity of the inferior olive. We determined whether a change in serotonin content within the olivocerebellar system accompanied a predisposition to myoclonus and investigated the necessity of the inferior olive for a myoclonic seizure. The experiments employed the genetically epilepsy-prone rat that exhibits a profound myoclonic seizure in response to an auditory stimulus. We found that these animals demonstrated a significant reduction in the serotonergic innervation of the inferior olive without a significant change in the serotonergic innervation at any other level of the olivocerebellar circuit. The deficit in olivary serotonin was verified physiologically and pharmacologically by a reduced sensitivity of the genetically epilepsy-prone rat to the tremorogenic effect of harmaline, which is known to produce tremor through a mechanism that requires serotonergic innervation of the inferior olive. We quantified the timing of the myoclonic seizure of the genetically epilepsy-prone rat and found that its large amplitude 2-6 Hz clonus was always preceded by 9-10 Hz tremor that was synchronized among limbs. Ablation of the inferior olive by 3-acetylpyridine abolished the myoclonic seizure. The specificity of the deficit in olivary serotonin, the timing of the seizure, and the demonstration of the necessity of the inferior olive for myoclonus suggest that pathological inferior olivary activity contributes to the genesis of a myoclonic seizure. 相似文献
1000.
SA Cleaver P Warren M Kern CK Hurley C Raffoux J Keller U Kiesel V Koza E Marry A Mitterschiffthaler M Nakamura CT Okah U Persson T Radde-Stepaniak L Ranson J Raymond M do Rosario Sancho M Varla-Leftherioti T Wiegand JM Winterhager DG Woodfield 《Canadian Metallurgical Quarterly》1997,20(8):621-629
In October 1995 the World Marrow Donor Association (WMDA) was restructured in order to facilitate its primary function of establishing guidelines in relation to international bone marrow and blood stem cell transplants -- transplants in which the donor is in one country and the patient is in another country. Five new working groups were established -- Donor Registries, Ethics, Quality Assurance, Finances, and Stem Cells. This paper, prepared by members of the Donor Registries Working Group, in consultation with the Quality Assurance Working Group, provides recommendations for the 'donor work-up'. This term covers events that start when the definitive donor has been identified, includes the harvesting (collection) and transportation of the stem cell product and ends when the product reaches the transplant centre. The paper includes examples of the documentation intended to ensure compliance with the recommendations at all key points in the sequence. 相似文献