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61.
H Inoue J Ferrer M Warren-Perry Y Zhang H Millns RC Turner SC Elbein CL Hampe BK Suarez N Inagaki S Seino MA Permutt 《Canadian Metallurgical Quarterly》1997,46(3):502-507
The septate gregarine parasites of flour beetles (Tribolium spp.) include Gregarina minuta Ishii, 1914, a relatively small species in which both primite and satellite possess an obvious protomerite, and a larger species that lacks the satellite protomerite. The latter species has been placed in the genera Didymophyes and Hirmocystis by various authors, but studies reported here demonstrate that this species, herein described as Gregarina triboliorum, exhibits early pairing and produces oocyst chains, both characteristics of the genus Gregarina. The oocysts of this new species are described for the first time. In addition, experimental infections using oocyst from single gametocysts reveal that oocyst chain number is variable but is typically 1, 2, or 4. Prior experiments involving a related beetle, Tenebrio molitor, demonstrated extreme host specificity within the 4 Gregarina species parasitizing larval and adult hosts. However, G. triboliorum is not limited either stadially or specially, infecting both adults and larvae of Tribolium confusum and Tribolium castaneum. 相似文献
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BK Ganser S Li VY Klishko JT Finch WI Sundquist 《Canadian Metallurgical Quarterly》1999,283(5398):80-83
The genome of the human immunodeficiency virus (HIV) is packaged within an unusual conical core particle located at the center of the infectious virion. The core is composed of a complex of the NC (nucleocapsid) protein and genomic RNA, surrounded by a shell of the CA (capsid) protein. A method was developed for assembling cones in vitro using pure recombinant HIV-1 CA-NC fusion proteins and RNA templates. These synthetic cores are capped at both ends and appear similar in size and morphology to authentic viral cores. It is proposed that both viral and synthetic cores are organized on conical hexagonal lattices, which by Euler's theorem requires quantization of their cone angles. Electron microscopic analyses revealed that the cone angles of synthetic cores were indeed quantized into the five allowed angles. The viral core and most synthetic cones exhibited cone angles of approximately 19 degrees (the narrowest of the allowed angles). These observations suggest that the core of HIV is organized on the principles of a fullerene cone, in analogy to structures recently observed for elemental carbon. 相似文献
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1. The effects of the nitric oxide (NO) synthase inhibitor, NG-nitro-L-arginine (L-NOARG), the NO scavenger, oxyhaemoglobin (HbO) and high extracellular K+ upon endothelium-dependent relaxation to bradykinin were investigated in human isolated small coronary arteries. 2. Endothelium-dependent relaxations to bradykinin were compared in vessels contracted to approximately 50% of their maximum contraction to 124 mM KCl Krebs solution, regardless of treatments, with the thromboxane A2 mimetic, U46619 and acetylcholine. All relaxations were expressed as percentage reversal of the initial level of active force. 3. L-NOARG (100 microM) caused a small but significant, 12% (P < 0.01), decrease in the maximum relaxation (Rmax: 91.5 +/- 5.4%) to bradykinin but did not significantly affect the sensitivity (pEC50: 8.08 +/- 0.17). Increasing the concentration of L-NOARG to 300 microM had no further effect on the pEC50 or Rmax to bradykinin. HbO (20 microM) and a combination of HbO (20 microM) and L-NOARG (100 microM) reduced Rmax to bradykinin by 58% (P < 0.05) and 54% (P < 0.05), respectively. HbO (20 microM) and L-NOARG (100 microM, combined but not HbO (20 microM) alone, caused a significant 11 fold (P < 0.05) decrease in sensitivity to bradykinin. HbO (20 microM) decreased the sensitivity to the endothelium-independent NO donor, S-nitroso-N-acetylpenicillamine (SNAP), approximately 17 fold (P < 0.05). 4. Raising the extracellular concentration of K+ isotonically to 30 mM, reduced the Rmax to bradykinin from 96.6 +/- 3.1% to 43.9 +/- 10.1% (P < 0.01) with no significant change in sensitivity. A combination of HbO, L-NOARG and high K+ (30 mM) abolished the response to bradykinin. High K+ did not change either the sensitivity or maximum relaxation to SNAP. 5. In conclusion, L-NOARG does not completely inhibit endothelial cell NO synthesis in human isolated small coronary arteries. By comparison, HbO appeared to block all the effects of NO in this tissue and revealed that most of the relaxation to bradykinin was due to NO. The non-NO -dependent relaxation to bradykinin in the human isolated small coronary arteries appeared to be mediated by a K(+)-sensitive vasodilator mechanism, possibly endothelium-derived hyperpolarizing factor (EDHF). 相似文献
67.
M Singh JR Corboy JC Stears BK Kleinschmidt-DeMasters 《Canadian Metallurgical Quarterly》1998,50(4):356-62; discussion 362
BACKGROUND: Widespread dissemination of astrocytoma throughout the cerebrospinal fluid is unusual, especially as the initial presentation in a patient, and association with cerebral infarcts is rare. CASE DESCRIPTION A 47-year-old man subacutely developed progressive headache and backache, vomiting, altered consciousness, and numbness in both arms. Brain computerized axial tomography showed calcification in the fourth ventricle and magnetic resonance imaging demonstrated diffuse meningeal enhancement, a lesion in the canal of Magendie, and T2-weighted hyperintense lesions in several locations. Angiography showed vasospasm/vasculopathy involving multiple cerebral vessels. Biopsy of the fourth ventricular mass revealed a subependymoma with an overlying leptomeningeal anaplastic astrocytoma with numerous Rosenthal fibers. The patient was treated with three doses of intrathecal methotrexate via lumbar puncture but suddenly became unresponsive and died 6 days later, 8 weeks after initial symptoms. Autopsy demonstrated the subependymoma and a widespread leptomeningeal anaplastic astrocytoma, which showed no clear-cut origin from the subependymoma, but microscopically infiltrated the left medial temporal lobe. Multiple subacute and acute infarcts of the brain, brain stem, and upper spinal cord were seen only in areas with leptomeningeal tumor. CONCLUSION Glioma cells surrounding and focally permeating central nervous system vessels without lumenal occlusion can lead to vasospasm and widespread infarcts. 相似文献
68.
HI Pass DJ Mew KC Kranda BK Temeck JS Donington SA Rosenberg 《Canadian Metallurgical Quarterly》1996,61(6):1609-1617
BACKGROUND: A phase I trial was initiated to define the feasibility and safety of single-lung isolation perfusion with tumor necrosis factor-alpha, interferon-gamma, and moderate hyperthermia for patients with unresectable pulmonary metastases. METHODS: Twenty patients with lung metastases (Ewing's, 2; sarcoma, 8; melanoma, 6; other, 4) were considered for single-lung isolation perfusion with 0.3 to 6.0 mg of tumor necrosis factor-alpha and 0.2 mg interferon-gamma delivered through an oxygenated pump circuit. Sixteen perfusions were performed in 15 patients (bilateral in 1). Metastases were completely resected (no single-lung isolation perfusion) in 3 patients, 1 patient had extrapulmonary disease, and one single-lung isolation perfusion was aborted for mechanical reasons. RESULTS: There were no significant changes in systemic arterial blood pressure or cardiac output during perfusion. Systolic pulmonary artery pressure increased with isolation, but returned to pre-single-lung isolation perfusion levels after clamp release. The maximum systemic tumor necrosis factor-alpha level was 8 ng/mL, whereas pump-circuit levels ranged from 200 to 10,976 ng/mL. There were no deaths, and the mean hospitalization period was 9 days (range, 5 to 34 days). A short-term (6 to 9 month) unilateral decrease in perfused nodules was noted in 3 patients (melanoma in 1, adenoid cystic carcinoma in 1, renal cell carcinoma in 1). CONCLUSIONS: Future studies using a combination of biologic modifiers, chemotherapy, and hyperthermia should be pursued to define active cytotoxic agents that will preserve underlying pulmonary function. 相似文献
69.
W Tan BK Felber AS Zolotukhin GN Pavlakis S Schwartz 《Canadian Metallurgical Quarterly》1995,69(9):5607-5620
70.
In this study the authors examine the effects of procedures adapted from the cognitive interview of R. E. Geiselman, R.P. Fisher, D.P. MacKinnon, and H.L. Holland (1985) on children's recall following exposure to misleading suggestions. Children aged 5-7 years and 9-11 years saw a videotaped story and were presented with misleading or neutral information concerning story details. All were later given free- and cued-recall tests preceded by standard interview instructions or instructions that reinstated the encoding context and encouraged exhaustive reporting. Increased recall accuracy was found following cognitive interview instructions. Both age groups were susceptible to misleading suggestions, but susceptibility was unaffected by interview type. The authors discuss the implications for interviewing child witnesses. 相似文献