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The flow-independent viscoelastic and equilibrium behaviors of canine articular cartilage were examined with time after transection of the anterior cruciate ligament. The equilibrium, transient, and dynamic shear behaviors of cartilage were studied in biaxial compression-torsion testing at two time periods after transection of the anterior cruciate ligament and at two sites on the femoral condyle, in order to test for differences between sites of frequent and less frequent contact. Water content also was measured in cartilage at sites corresponding to the areas of mechanical testing. Transection of the anterior cruciate ligament produced significant decreases in all measured moduli of articular cartilage tested in equilibrium and dynamic shear and in equilibrium compression; the values for these moduli were 61, 56, and 77% of the control values, respectively, beginning at 6 weeks following transection of the anterior cruciate ligament. There was evidence of increased energy dissipation of cartilage in shear, with a 13 and 35% increase in tan δ at 6 and 12 weeks after transection of the anterior cruciate ligament, respectively. Changes in the viscoelastic relaxation function of cartilage in shear also were evident at 12 weeks after surgery. In all tissue, there was a significant increase in hydration of approximately 4% at 6 or 12 weeks after surgery. There was little difference between the material parameters for areas considered to be in frequent and less frequent contact, with the exception of hydration, which was greater for areas of less frequent contact. The observed changes in material properties demonstrate that relatively short periods of joint instability result in significant changes in the flow-independent viscoelastic behavior of articular cartilage, as well as in the intrinsic stiffnesses in compression and shear. 相似文献
13.
Respiratory symptoms among elderly people in the New Forest area as assessed by postal questionnaire. 总被引:3,自引:0,他引:3
This study was carried out to estimate the prevalence of respiratory symptoms among people aged 65 years and older and assess the value of a postal survey in obtaining this information. A questionnaire was sent to 2011 subjects (957 men) drawn by age-stratified random sampling from the age-sex registers of four New Forest group practices (1:3.3 sample). A total of 1803 replied, a 96.2% response after excluding 136 who had died or moved from the area. The accuracy of replies was verified for 355 (20%) randomly selected subjects. Forty per cent had no respiratory symptoms. Exertional breathlessness was common (38%), increasing in prevalence with age but not with smoking history, and was the only symptom reported by 10% of subjects. Only 14.2% were current smokers; more of the subjects aged 85 years and over were lifelong non-smokers. Two hundred and ninety-six (16.4%) had chronic bronchitis, which was more common among smokers; 151 (8.4%) gave a history of asthma, of whom half (76) had active asthma, which was slightly less common among the very elderly subjects. Only 489 (27.1%) of subjects had seen their doctors with chest symptoms during the preceding 2 years. 相似文献
14.
A O Goldstein W R Westbrook R E Howell P M Fischer 《The Journal of family practice》1992,34(6):729-734
BACKGROUND. This study reports the barriers and challenges for hospital tobacco control efforts after the institution of smoke-free policies. METHODS. Surveys of employees and inpatients of five hospitals in Augusta, Georgia, were conducted and evaluated 4 months after joint hospital implementation of smoke-free policies. A random sample of 1997 employees and a convenience sample of 517 inpatients returned usable surveys. RESULTS. Although attitudes to the hospital bans on smoking reflected strong support for smoke-free policies, four out of five hospitals reported significant implementation problems. Despite the bans, 49% of patients who were smokers continued to smoke while hospitalized, and almost one half of all hospitalized smokers had received no advice to quit smoking from a physician or a nurse since admission. Employees and patients both agreed that the smoke-free policies had benefited employees more than patients. CONCLUSIONS. Despite achieving a smoke-free status, there are many challenges that remain for comprehensive hospital tobacco-control efforts. Hospitals and health care professionals must remain particularly alert and attentive to the needs of patients and employees still addicted to tobacco. 相似文献
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DA Taylor 《Environmental health perspectives》2002,110(9):A512-A513
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W M Howell S J Turner A Collins A C Bateman J M Theaker 《European journal of immunogenetics》2002,29(1):17-23
Cutaneous malignant melanoma (CMM) is a potentially fatal malignancy in which exposure to UV light is the most important risk factor. Several lines of evidence suggest that increased expression of tumour necrosis factor (TNF) alpha, upregulated by UV exposure, may contribute to tumour escape from the immune response. In this study, we addressed whether single nucleotide polymorphisms (SNPs) in the TNFalpha promoter and lymphotoxin (LT) alpha gene are associated with susceptibility to or known prognostic indicators (e.g. initial tumour growth phase, Breslow thickness, mitotic count in vertical growth phase tumours, and tumour regression) in CMM. One hundred and forty-six British Caucasian CMM patients and 220 controls were typed for TNFalpha-376, -308 and -238 and LTalpha+252 SNPs by ARMS-PCR. Only the TNFalpha -238 GG (P = 0.05) and GA (P = 0.03) genotypes showed slight, but significant, associations with CMM, while LTalpha+252 AA was associated with a higher mitotic count in vertical growth phase tumours (P = 0.02). Both TNFalpha-238 and LTalpha+252 SNPs showed linkage disequilibrium with HLA-DQB1*0303 and *0301 alleles, variably implicated in CMM susceptibility/prognosis. In addition, TNFalpha-238, -308, LTalpha+252 haplotypes were assigned and compared. The GGA haplotype showed a modest association with CMM (P = 0.04) and with stage of disease (P = 0.03) and initial growth phase in CMM (P = 0.02), but these associations were only significant when P-values were uncorrected. Unlike basal cell carcinoma, these preliminary findings suggest that genetic variation associated with differential TNFalpha and LTalpha production is unlikely to play a major, independent role in susceptibility to, and perhaps prognosis in, CMM. 相似文献
19.
Nitric oxide is not involved in the initiation of insulin secretion from rat islets of Langerhans 总被引:1,自引:1,他引:0
P. M. Jones S. J. Persaud T. Bjaaland J. D. Pearson S. L. Howell 《Diabetologia》1992,35(11):1020-1027
Summary The involvement of nitric oxide as an intracellular messenger in the control of insulin secretion from pancreatic Beta cells was studied in rat islets of Langerhans by measuring: (i) nitric oxide generation in response to physiological insulin secretagogues; (ii) the effects of inhibitors of nitric oxide synthesis on insulin secretory responses to physiological secretagogues, and on insulin synthesis; (iii) changes in islet cyclic guanosine monophosphate in response to secretagogues; (iv) the effects of exogenous cyclic guanosine monophosphate and dibutyryl cyclic guanosine monophosphate on insulin secretion from electrically permeabilised islets and from intact islets, respectively. These studies produced no evidence that nitric oxide generation is required for the initiation of insulin secretion by common secretagogues. However, the results of our experiments suggest that the generation of nitric oxide may be involved in long-term, glucose-dependent increases in cyclic guanosine monophosphate content of islet cells, although the physiological relevance of these changes requires further investigation. 相似文献
20.