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51.
Mining and resource recovery activities have not been kind to ecosystems in the Sudbury basin, Ontario. The combination of logging, smelting, fires and erosion resulted in an unusual anthropogenic ecosystem of denuded barren land with lifeless lakes, or a micro-desert. Since the 1970s, however, the concerted efforts made to reduce the emissions and rehabilitate parts of the degraded ecosystem have resulted in improvements in water quality, and recoveries in phytoplankton, zooplankton, zoobenthos and fish communities but have had little impact on toxic metal concentrations in many lakes. We show that most of the catchments in the Sudbury basin have become saturated with Cu and Ni, and some with Zn and Pb. It is estimated that mobilization of metals stored in soils and glacial overburden by surface runoff, groundwater drainage and wind re-working of tailings can sustain the high concentrations of Cu and Ni in many lakes for well over 1000 years. Strategies to immobilize the pollutant metals in the watershed rather than further emission controls may be required for dealing with high levels of toxic metals in surface waters of the saturated ecosystems. 相似文献
52.
HK Kimelberg 《Canadian Metallurgical Quarterly》1998,19(1):27-34; discussion 37-8
53.
HK Parmentier G De Vries Reilingh MG Nieuwland 《Canadian Metallurgical Quarterly》1998,66(3-4):367-376
Mitogen-induced cutaneous hypersensitivity was evaluated in chickens selected for high and low antibody responses to SRBC, and in a random bred control line. Wing web swelling responses were found after subcutaneous administration of phytohemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM), and Escherichia coli lipopolysaccharide (LPS), respectively, in all three lines. All mitogens induced significant acute 4 h wing web swelling responses, followed by a significant (classical) late 24 h wing web swelling response. The 4 h responses were significantly lower in the L line, whereas a tendency for lower responses at 24 h in the L line was found as well. Immunohistochemical evaluation of the early and late wing web swelling responses revealed extravascular localisation of leukocytes at 24 h after sensitization with mitogens, which consisted of CD4+ cells, CD8+ cells, TCR-1+ cells, and heterophils, but no B cells, whereas the 4 h swelling response was primarily characterized by oedema. Cutaneous hypersensitivity either initiated by T-cell mitogens as well as B-cell mitogens may depend for an important part on the rapid induction of local homing of lymphocytes towards the sensitizing agent, which may be mediated by an acute local expression of molecules with chemo-attractive capacities. Interpretation of cellular immunity responses in vivo such as delayed-type hypersensitivity should therefore incorporate oedema-initiating characteristics of sensitizing agents. The relationship between the magnitude of cutaneous hypersensitivity to mitogens and selection for antibody responsiveness is discussed. 相似文献
54.
DL Forman HK Watson KA Caulfield J Shenko AE Caputo D Ashmead 《Canadian Metallurgical Quarterly》1998,23(6):1010-1014
Immunohistochemistry was applied in the investigation of the possible existence of serotonin in human skin. It was found that epidermal melanocytes express a serotonin-like immunoreactivity. The immunoreactivity was associated with both the cytoplasm and the cellular membrane, though the latter was only found in certain cells. The serotonin anti-serum labeled the same cells as NKI-beteb, which is known as a reliable marker of melanocytes. Blocking experiments showed that both serotonin and NKI-beteb have different epitopes in the melanocytes. In in vitro studies, serotonin-like immunoreactivity appeared in approximately 90% of cultured human melanocytes, and was found both in the cytoplasm and also in the nuclei. Thus, we believe the melanocytes to be the origin of serotonin (or a serotonin-like molecule) in the skin. 相似文献
55.
Expression/induction of the 72 and 60 kDa heat shock proteins (HSPS 72 and 60) in cultured human keratinocytes by high calcium was studied with immunofluorescent staining and the flow cytometric method. Normal human keratinocytes cultured in serum free, low calcium medium (Ca2+, 0.1 mM) at 3-passage weakly expressed HSP 60, but not HSP 72, as fine granules in the cytoplasm. HSP 72 was induced in the perinuclear cytosomal area and then in the nucleus after transferring the cells in high calcium medium (Ca2+, 1.8 mM). Whereas the nuclear accumulation began to decrease 24 h after the treatment, the perinuclear cytosomal staining continued. High calcium also augmented the expression of HSP 60 as coarse granules in the cytoplasm. Flow cytometric analyses quantitatively revealed the induction of HSP 72 and the upregulation of HSP 60 by high calcium treatment. Our results clearly demonstrated that extracellular calcium concentration modifies the level of expression of HSP 72 and 60 in normal human keratinocytes, indicating the importance of the careful attention to medium condition in evaluating the expression of HSPS 72 and 60 in cultured keratinocytes. 相似文献
56.
AP Evan DP Henry BA Connors P Summerlin WH Lee 《Canadian Metallurgical Quarterly》1995,48(5):1517-1529
Immunocytochemistry, in situ hybridization, and radioimmunoassay were employed to examine the cellular distribution of mRNAs and proteins for IGF-I, II, IGF-II/M6P receptor, IGFBP2 as well as the levels of IGF-I and II in normal and unilaterally nephrectomized (Nx) adult rat kidneys. A similar distribution of immunoreactive IGF-I, and -II as well as IGF-II/M6P receptor was found in the principal cells of the cortical collecting duct and in all cells of the inner medullary collecting duct. In addition, immunostainable IGF-I and IGF-II/M6P receptor were noted in some inner medullary loops of Henle, while IGFBP2 was seen in the collecting ducts and loops of Henle of the inner medullar and the renal vasculature of all animals. By comparison, in situ hybridization revealed IGF-I mRNA only in the medullary thick ascending limbs while IGF-II mRNA was localized to the wall of the renal microvasculature in all kidneys. IGFBP2 mRNA was localized to the renal corpuscle and to inner medullary interstitial cells of all kidneys. These data suggest that renal IGF-I and IGFBP2 are synthesized at upstream sites along the nephron and then transported downstream for interaction with IGF receptors. Following nephrectomy, the renal levels of IGF-I peptide and mRNA were elevated at both 5 and 33 days post-nephrectomy, supporting a potential functional role for IGF-I in stimulating the structural and functional recovery in compensatory hypertrophy. 相似文献
57.
BACKGROUND AND OBJECTIVES: The para-Bombay phenotype has a relatively high frequency of about 1 in 8,000 Taiwanese. Studies were carried out on eight healthy and unrelated Taiwanese with the para-Bombay phenotype to cast light on its immunogenetic basis. MATERIALS AND METHODS: Blood and saliva samples were tested with standard hemagglutination techniques. Salivary ABH substances were determined by hemagglutination inhibition. PCR techniques were used to amplify the coding region of the H genes. RESULTS: Five different h alleles, designated as h1, h2, h3, h4 and h5, were identified in the Taiwanese with the para-Bombay phenotype. The h1 allele loses one of the three AG repeats located at the nucleotides 547-552 of the H gene, whereas two of the three T repeats located at the nucleotides 880-882 are deleted in the h2 allele. The h3 allele contains a C658 to T missense mutation, whereas two missense mutations, C35 to T and A980 to C were identified in the h4 allele. A T460 to C missense is present in the h5 allele. The h5 allele was identified in an individual whose red blood cells contain blood group A antigen but not H antigen, and thus may be considered a weak variant of the H gene. CONCLUSIONS: So far no biologic relevance of the H antigen has been discovered, and its deficiency does not seem to produce any deleterious effects. There may be better understanding of the evolutionary basis for the polymorphisms at these loci after systematic study of different ethnic populations. 相似文献
58.
HK Yuen 《Canadian Metallurgical Quarterly》1997,51(9):780-783
Social skills often create a barrier to placement in less restrictive environments for persons with TBI. This case study illustrated the use of a positive talk program in the treatment of a person with long-standing social skill deficits. Occupational therapy intervention with speech-language consultation began with an evaluation of the cognitive barriers that influenced the client's social behavior. Work with the client's concrete concept formation, decreased memory, and poor generalization skills led to the development of the positive talk training program described. Through an understanding of the underlying cognitive deficits that influenced the client's behavior, the clinical team was able to develop an individual treatment plan. The intervention resulted in modification of behavior that would have required placing the client in a restricted environment. In the final analysis, the client's social skills improved to a level where he could be discharged to a less restrictive environment. 相似文献
59.
YK Jeong HK Ha CH Yoon G Gong PN Kim MG Lee YI Min YH Auh 《Canadian Metallurgical Quarterly》1997,168(4):965-968
OBJECTIVE: The purpose of this study was to describe the CT features of gastrointestinal involvement in seven patients with Henoch-Sch?nlein syndrome. CONCLUSION: Although the incidence of Henoch-Sch?nlein syndrome is low, it should be considered when CT scans show multifocal areas of bowel-wall thickening, mesenteric edema, vascular engorgement, and nonspecific lymphadenopathy. It should be considered especially in young patients with acute gastrointestinal symptoms. 相似文献
60.