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181.
Oxidative damage to the membrane in canine erythrocytes with inherited high Na, K-ATPase activity (HK cells) was compared with that in normal canine cells (LK cells). When 30 mM beta-acetylphenylhydrazine (APH) was applied to HK and LK cells, lipid peroxidation and hemoglobin denaturation occurred. Lipid peroxidation determined from malondialdehyde (MDA) formation was significantly lower in HK than in LK cells so far as endogenous glutathione (GSH) concentration was maintained at appropriate levels. With the depletion of GSH, MDA formation was accelerated and difference between HK and LK cells was not significant. Denatured hemoglobin bound to the membrane protein was less in HK than in LK cells. During incubation with APH, osmotic fragility increased markedly in LK cells, while HK cells showed very little change. The amounts of total lipid, total and free cholesterol, glycolipid, phospholipid and fatty acids were essentially the same in both cell types. Fatty acid compositions showed very small differences. The membrane of HK cells thus appear to have greater protection against oxidative damage induced by APH, owing to the presence of excess GSH in HK cells. The capability of HK cells to withstand oxidative damage would not be due to differences in membrane lipid compositions.  相似文献   
182.
Bovine cumulus-oocyte complexes (COCs) were aspirated from antral follicles (3–6 mm in diameter). COCs with a compact multilayered cumulus investment were cultured for 9, 13 and 24 hours, respectively, and processed for scanning or transmission electron microscopy after different periods of culture including a 0 hour control group. In all 0 hour control COCs initial formation of cumulus cell projections, blebs and microvilli were observed. The start of cumulus-oocyte disconnection in cattle was observed after 9 hours of in vitro culture. These connections were almost completely discrupted after 13 hours, when a continuous production of extracellular matrix was observed. The full expansion of corona radiata cells was not observed even after 24 hours. Some cumulus oophorus cells were bound together with junctions of the zonula adherens type after 24 hours when extracellular matrix was found only in deeper layers. The full expansion of corona radiata cells was not the prerequisite for disconnection of cumulus-oocyte complex. Inhalt: Kumulus oophorus Expansion von in vitro kultivierten Rinderoozyten: Eine SEM und TEM Untersuchung Kumulus-Oozyten-Komplexe (COC) von Rindern wurden aus antralen Follikeln aspiriert (Durchmesser 3–6 mm). COC's mit kompakten mehrschichtigen Kumulus wurden für 9, 13 und 24 Stunden kultiviert und für die Scanner- oder Transmissionselektronenmikroskopie vorbereitet. Verschiedene Kulturzeiten incl. einer 0-Stundengruppe als Kontrolle wurden untersucht. In allen Kontroll COC's wurden beginnende Formationen yon Kumuluszellprojektionen, Bläschen und Mikrovilli beobachtet. Nach 9-stündiger in vitro Kultur begann die Lösung zwischen Kumulus und Oozyte. Die Verbindungen waren nach 13 Stunden vollständig unterbrochen, wobei eine kontinuierliche Produktion extrazellulärer Matrix beobachtet wurde. Eine vollständige Expansion der Corona radiata Zellen wurde auch nicht nach 24 Stunden beobachtet. Nach 24 Stunden waren einige Cumulus Oophorus Zellen über Verbindungen des Zonula adherens Typs verknüpft, wobei extrazelluläre Matrix nur in den tieferen Zellschichten gefunden wurde. Eine vollständige Kumulusexpansion ist keine Voraussetzung für die Auflösung des Kumulus-Oozyten-Komplexes.  相似文献   
183.
Root length of Holcus lanatus L. declined rapidly with increasing lead and zinc concentrations in nutrient solution. In all used Pb and Zn concentrations root growth of genotypes coming from a Pb-Zn mine area, was greater than that of the control, suggesting that these genotypes evolved tolerance to Pb and Zn.
Negative correlation was also observed between chlorophyll content and increased heavy metal concentrations. The greater chlorophyll content found in tolerant genotypes, in different Pb and Zn concentrations, in comparison with the control, could be served to distinguish tolerant and non-tolerant genotypes.  相似文献   
184.
Osteolytic defects were detected radiographically in the distal sesamoid bone of a 16-month-old Bralers heifer, in the middle phalanx of a 14-month-old American Gray Brahman bull, and in the distal phalanx of a 3-year-old American Gray Brahman bull. The articular cartilage was damaged in each animal because of osteolysis or pathologic fracture. After each animal was anesthetized and positioned in lateral recumbency, the lesions were curetted and packed with cancellous bone harvested from the same animal's tuber coxae. Basic postoperative management involved stall rest and immobilization of the graft site with a fiberglass cast (42 to 79 days), after which a support bandage was used for approximately 2 weeks. Recurrence of lameness has not been observed in these animals for 60 months, 58 months, and 21 months, respectively. These cases exemplify the benefit of using an autogenous cancellous bone graft for treatment of severe osteolysis of a digit in cattle.  相似文献   
185.
Two mungbean varieties, Guj-1 and PIMS-1 differing in their productivity potential, were examined to investigate their photosynthetic system at various stages of growth in relation to yield with two different dates of sowing. Vertical leaves were found to be beneficial. On the other hand, excessive leaf area during the later stages of growth may be detrimental to yield. Lower LAD at seedling stage and overall high NAR values may be reflected in higher grain yield. NAR declined as season progressed and this, in turn, may be related with increase in LAI. The grain yield was considerably more at the first date of sowing as compared to second date of sowing, the effect was being more pronounced in var. PIMS-1 . Various environmental factors recorded at two different dates of sowing and at various stages of growth indicated that these factors may have influenced the yield potential at two different dates of sowing.  相似文献   
186.
Dynamics of the cumulation of phosphorus, potassium, calcium and magnesium in developing seed of four soybean genotypes under the defined climatic conditions in the course of three years was observed. Samples were being taken at weekly intervals from the point at which the grain reached a size suitable to be analyzed up to the full maturity of the seed. By analyzing the results it was found out that the intense cumulation of the minerals tested took place during the stages III and IV of the seed development, that is, in the course of intense cumulation of dry matter and the most expressive metabolic activity in the seed. Investigation of the impact of climatic conditions provides evidence that cumulation of the tested macroelements has been favourably influenced by increased precipitation along with moderate air temperatures within the seed developing period. The highest content of the minerals found with the cultivar Maksimirka independently of the year investigated reveals that mineral cumulation in soybean seed is affected by the cultivar and genetic particularity.  相似文献   
187.
Chloroform-methanol (2:1 v/v), absolute methanol, and 90% acetone were evaluated for their effectiveness as extractants of chlorophyll a from samples of phytoplankton communities collected from catfish ponds. Chloroform-methanol consistently extracted more chlorophyll a than either 90% acetone or methanol. Precision for the methanol extraction was also unacceptably low, with an average coefficient of variation of 17%. Average coefficients of variation for the chloroform-methanol and 90% acetone extraction procedures were 6 and 5%, respectively. Filtered samples should be steeped in chloroform-methanol for at least 4 h to obtain maximum chlorophyll extraction, and the addition of MgCO3 to the extractant as a buffer is not necessary.  相似文献   
188.
Abstract. Three cases of skeletal muscle neoplasms occurring in two small fish species used in carcinogen tests are reported. The cases illustrated a wide range of histologic patterns, and consisted of a well-differentiated juvenile type, a well-differentiated pleomorphic type and a poorly differentiated pleomorphic type. A rhabdomyosarcoma with juvenile type features developed in the Japanese medaka, Oryzias latipes , exposed to 0·5 ml/1 of the solvent dimethylformamide. A pleomorphic type rhabdomyosarcoma occurred in one medaka and in one guppy, Poecilia reticulata , exposed to the carcinogen methylazoxymethanol acetate. These cases indicate the potential for skeletal muscle cells in medaka and guppy to become neoplastic but, because the tumours occurred at a low frequency, there may not necessarily be a chemical aetiology.  相似文献   
189.
Abstract. Recent developments in in situγ ray spectrometry offer a new approach to measuring the activity of radionuclides such as 137Cs and 40K in soils, and thus estimating erosion or deposition rates and field moist bulk density (ρm). Such estimates would be rapid and involve minimal site disturbance, especially important where archaeological remains are present. This paper presents the results of a pilot investigation of an eroded field in Scotland in which a portable hyper pure germanium (HPGe) detector was used to measure γ ray spectra in situ. The gamma (γ) photon flux observed at the soil surface is a function of the 137Cs inventory, its depth distribution characteristics and ρm. A coefficient, QCs, derived from the forward scattering of 137Cs γ ray photons within the soil profile relative to the 137Cs full energy peak (662 keV), was used to correct the in situ calibration for changes in the 137Cs vertical distribution in the ploughed field, a function of tillage, soil accumulation and ρm. Based on only 8 measurements, the agreement between in situγ ray spectrometry and soil sample measurements of 137Cs inventories improved from a non significant r2=0.05 to a significant r2=0.62 (P<0.05). Erosion and deposition rates calculated from the corrected in situ137Cs measurements had a similarly good agreement with those calculated from soil cores. Mean soil bulk density was also calculated using a separate coefficient, QK, derived from the forward scattering γ photons from 40K within the soil relative to the 40K full energy peak (1460 keV). Again there was good agreement with soil core measurements (r2=0.64; P<0.05). The precision of the in situ137Cs measurement was limited by the precision with which QCs can be estimated, a function of the low 137Cs deposition levels associated with the weapons testing fallout and relatively low detector efficiency (35%). In contrast, the precision of the in situ ρm determination was only limited by the spatial variability associated with soil sampling.  相似文献   
190.
Squamous cell carcinoma is an uncommon tumor of the cornea in dogs. A 12-year-old Shih Tzu with a history of chronic keratoconjunctivitis sicca was diagnosed as having squamous cell carcinoma of the corneoscleral limbus. The lesion was treated by surgical resection and cryotherapy. One year after surgery, multiple tumors, apparently unrelated to the first tumor, appeared on the same cornea. Keratoconjunctivitis sicca may have predisposed the dog to corneal squamous cell carcinoma development.  相似文献   
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