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991.
992.
SCHWANN CELLS AND THE REGROWTH OF AXONS IN THE MAMMALIAN CNS: A REVIEW OF TRANSPLANTATION STUDIES IN THE RAT VISUAL SYSTEM 总被引:2,自引:0,他引:2
A. R. Harvey G. W. Plant M. M. L. Tan 《Clinical and experimental pharmacology & physiology》1995,22(8):569-579
1. We have used peripheral nerve transplants or cultured Schwann cells grafted in association with different types of polymer to study axonal regrowth in the rat visual system. In some instances the glia were co-grafted with fetal tectal tissue. 2. The studies have two main aims: (i) to determine whether retinal axons can be induced to regrow at a site distant from their cell soma, that is, after damage to the brachial region of the optic tract; (ii) to determine whether retinal axons exposed to Schwann cells retain the ability to recognize their appropriate target neurons in CNS tissue. 3. In brachial lesion studies, Schwann cells were placed in the lesion site in association with nitrocellulose papers, within polycarbonate tubes in the presence or absence of a supporting extracellular matrix (ECM), or within polymer hydrogel scaffolds. Autologous sciatic nerve grafts were also used. Immuno-histochemical studies revealed the presence of regenerating axons within all polymer bridges. Regrowth of retinal axons was also seen, however, growth was not extensive and was limited to the proximal 1–1.5 mm of the implants. 4. In target innervation experiments, two surgical paradigms were developed. In one experiment, a segment of sciatic nerve was autografted onto the transected optic nerve in adult rats and the distal end of each graft was placed adjacent to fetal tectal (target) tissue implanted into the frontal cortex. To date, we have not been able to demonstrate selective recognition of target regions within tectal transplants by retinal axons exiting the sciatic nerve implants. 5. In the second experiment, Schwann cells were mixed with fetal tectal cells and co-grafted to the midbrain of newborn host rats. Schwann cells altered the characteristic pattern of host retinal growth into tectal grafts; in some cases axons were induced to grow away from appropriate target areas by nearby co-grafted Schwann cells. 6. In summary, Schwann cell/polymer scaffolds may provide a useful way of promoting the regrowth of damaged axons in the CNS, however: (i) in adults, at least, their effectiveness is reduced if they are located at a distance from the cell bodies giving rise to regenerating axons; (ii) in some circumstances exposure to a peripheral glial environment may affect the capacity of regenerating axons to recognize appropriate target cells in the CNS neuropil. 相似文献
993.
运动大鼠不同水平蛋白质摄入量研究 总被引:3,自引:1,他引:2
实验采用Wistar雄性大鼠,三种蛋白质摄入水平(7%、17%、27%),观察运动对大鼠蛋白质代谢的影响,为探讨运动和体力劳动人群适宜蛋白质需要量研究提供实验室依据。结果表明:运动可降低氮平衡值,运动后,血清尿素氮和氨基酸水平均增高,排肠肌氮含量降低。不同蛋白质摄入水平的大鼠影响程度各异。17%和27%蛋白质摄入水平大鼠体重增长无明显差别,均优于7%蛋白质摄入水平的大鼠。运动后,7%蛋白质摄入水平大鼠的蛋白质分解作用较强,未见27%蛋白质摄入水平优于17%者,对于急性高强度运动,17%蛋白质摄入水平可能是适宜的。 相似文献
994.
995.
J. G. BLIGH 《Medical education》1992,26(6):497-502
Self-directed learning is a natural way for adults to learn. Vocational training for general practice is a preparation for unsupervised clinical work that will be supported, in the main, by continuing medical education. This study uses the Self-Directed Learning Readiness Scale to investigate factors influencing readiness for such learning among a sample of general practice trainees. Three principal factors emerged from analysis: enjoyment and enthusiasm for learning; a positive self-concept as a learner and a factor suggesting the possibility of a 'reproducing' orientation to learning. These factors may reflect approaches to learning in general rather than these adopted for professional learning, but offer helpful pointers for the development of both vocational training and of continuing medical education. 相似文献
996.
N. Zamberlan R. Castello D. Gatti M. Rossini V. Braga E. Fracassi Prof. S. Adami 《Osteoporosis international》1997,7(2):133-137
Treatment with gonadotropin-releasing hormone (GnRH) agonist leads to enhanced bone turnover and accelerated bone loss in premenopausal women with endometriosis, uterine leiomyomatomas and hirsutism. Sodium etidronate is a powerful inhibitor of bone resorption which has been proven efficacious in the prevention and treatment of postmenopausal osteoporosis. The objective of this study was to evaluate the skeletal effects of 6 months of therapy with the depot preparation of the GnRH agonist triptorelin (decapeptil 3.75 mg intramuscularly every 4 weeks) in 24 hirsute patients, aged 24–33 years, with hyperandrogenic chronic anovulation. Ten patients also received cyclical etidronate in an oral dose of 400 mg/day for 2 weeks, followed by an 11-week period of 500 mg/day elemental oral calcium (one cycle). The remaining 14 patients received 500 mg/day of elemental calcium continuously. After 6 months all treatments were discontinued for at least a further 6 months. Bone mineral density (BMD) at lumbar spine and hip (dual-energy X-ray absorptiometry, Sophos LXRA, France) and biochemical markers (serum alkaline phosphatase, osteocalcin, urinary N-telopeptide and hydroxyproline/creatinine ratio) were evaluated at baseline, 6 months and 12 months. In the group given GnRH agonist alone BMD fell significantly at all measured skeletal sites during the first 6 months. In the patients treated with etidronate a significant decrease in BMD was observed at lumbar spine but not in the femoral neck and trochanter, and the changes at lumbar spine and trochanter were significantly smaller than those in the control group. At 6 months bone turnover was also increased in patients treated with GnRH and calcium. Cyclical etidronate prevented the increase in biochemical markers of bone formation and resorption, with the exception of calcium/creatinine excretion, which was significantly increased in both groups. Six months after treatment withdrawal BMD did not recover in either group. Biochemical markers (N-telopeptide, serum alkaline phosphatase) remained increased in those patients previously treated with calcium alone while they remained close to baseline values in the patients treated with cyclical etidronate.Our study indicates that: (1) GnRH agonist therapy causes remarkable bone loss in young individuals with androgen excess who are expected to have increased bone mass; (2) this bone loss can be partially prevented by intermittent cyclical etidronate therapy. 相似文献
997.
The effect of oral premedication was investigated in a double-blind, randomised trial in 85 children undergoing tonsillectomy and/or adenoidectomy. Orally administered midazolam 0.5 mg.kg−1 given 30 min pre-operatively was compared with trimeprazine 2 mg.kg−1 given 90 min pre-operatively and a placebo preparation. Compliance, sedation and ease of induction were assessed as were the duration and quality of recovery. Following premedication with midazolam none of the patients was anxious, crying or distressed on leaving the ward, compared with 2/28 in the trimeprazine group and 5/28 in the placebo group (p =0.0007). More patients were calm and quiet on arrival in the anaesthetic room following midazolam than following trimeprazine, with both premedicant agents comparing favourably with placebo. There was no significant difference between the three groups in the time to recovery or the sedation score on discharge to the ward. Midazolam is a safe and effective oral premedicant for children. 相似文献
998.
Marcel Stokkel Aeilko Zwinderman Jaap Zwartendijk Ernest Pauwels Berthe van Eck-Smit 《European journal of nuclear medicine and molecular imaging》1997,24(10):1215-1220
Between 10% and 25% of patients with newly diagnosed prostate cancer without bone metastases at the time of diagnosis will
develop metastases during follow-up. To determine the value of clinical and biochemical parameters for assessment of prognosis
at the time of diagnosis, a retrospective study was performed in 124 consecutive patients with newly diagnosed prostate cancer
without bone metastases. The mean follow-up was 41 months, during which time 36 patients died and 15 patients developed metastases.
Bone scans were classified from 0 (=normal) through 2 (=abnormal, but not typical for metastases) and were correlated with
age, alkaline phosphatase (AP), prostate-specific antigen (PSA), tumour grade, T-stage and N-stage. In patients with a class
2 scan, additional roentgenograms and follow-up were used to exclude metastases at initial stage. All parameters, including
therapy, were finally correlated with the development of metastases and survival. For survival 38 patients with proven metastases
were used as controls. For all parameters tested, no statistically significant differences were found between the three bone
scan classifications. The interval between diagnosis and the development of metastases ranged from 12 to 72 months. For the
risk of development of metastases only PSA was found to be a significant correlate (P=0.0075). However, when tumour stages were clustered in limited disease (T0–2) and extensive disease (T3–4), the incidence
of metastases was significantly higher in patients with extensive disease than in those with limited disease (P=0.0021). Finally, age, PSA and Anderson classification were found to be significant correlates of survival, but in stepwise
analysis PSA was selected as the most prognostic variable (P<0.0001). In contrast with a typical pattern of metastases on bone scintigraphy, an abnormal scan (class 1 and 2) at the time
of diagnosis is not a poor prognostic parameter of the risk of death. In conclusion, in patients with prostate cancer without
bone metastases at the time of diagnosis, pretreatment PSA and tumour stage can be used for the assessment of risk of development
of metastases during follow-up and survival. For this purpose, tumour stage should be clustered in limited and extensive disease.
Received 14 April and in revised form 9 June 1997 相似文献
999.
Carcinoma of the male breast: Analysis of prognosis compared with matched female patients 总被引:6,自引:0,他引:6
Dr. Patrick I. Borgen MD Ruby T. Senie PhD William M. P. McKinnon MD Paul Peter Rosen MD 《Annals of surgical oncology》1997,4(5):385-388
Background: Considerable debate exists concerning the prognosis of breast cancer in male patients compared with that in female patients.
Some studies have observed worse prognosis for men; others suggested the higher mortality rates were primarily due to delayed
diagnosis.
Methods: Survival time from diagnosis with invasive disease to death resulting from breast cancer of 58 men treated between 1973 and
1989 was compared with survival of 174 women treated between 1976 and 1978 who were matched by stage of disease and age at
diagnosis. All patients were treated by mastectomy and axillary dissection.
Results: Tumors were ⩽2 cm in 70% of cases and 55% were free of axillary metastases. The histology of the tumors differed significantly
by gender (p<0.05). Significantly more men had estrogen receptor-positive tumors (87%) than did women (55%, p<0.001). Survival
at 10 years was similar for male and female patients. Multivariate analysis controlling for tumor size, number of positive
axillary lymph nodes, age at diagnosis, histology, and receptor status indicated no significant difference in survival of
male compared with female patients.
Conclusions: These data conflict with the conventional wisdom that breast cancer in men carries a worse prognosis than the disease in
women. Although histology of the tumor and receptor status differed by gender, these factors did not have an impact on survival
in these paired patients. Our data indicate that breast carcinoma in males is not biologically more aggressive than in females.
Presented at the 49th Annual Cancer Symposium of The Society of Surgical Oncology, Atlanta, Georgia, March 21–24, 1996. 相似文献
1000.
A protein C deficient woman, with a past history of recurrent thrombosis and purpura fulminans, was successfully treated with protein C concentrate in the peripartum period. © 1992 Wiley-Liss, Inc. 相似文献