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1.
C F Nassar E W Khairallah M G Nasser Z M Habbal 《Comparative biochemistry and physiology. A, Comparative physiology》1988,89(2):197-201
1. The effect of colchicine, cytochalasin-B and procaine on calcium transport across the rat small intestine was investigated. The results obtained show the following: 2. Colchicine and cytochalasin-B at different concentrations inhibited significantly (P less than 0.001) calcium accumulation in rat intestinal cells, whereas procaine at different concentrations increased significantly (P less than 0.001) calcium accumulation in the rat small intestine. 3. Unidirectional influx of calcium across the rat small intestine was significantly inhibited (P less than 0.01) in the presence of colchicine and cytochalasin-B in the preincubation medium. Procaine, on the other hand, caused a significant increase (P less than 0.01) in the unidirectional influx of calcium across the rat intestinal cells. 4. The cell water content was not altered in the presence of the different drugs indicating that the changes in calcium transport across the rat intestinal cells are not due to alterations in the structure of the cell membrane. 相似文献
2.
A single dose of zearalenone (10 g/g LBW) was injected intraperitoneally to Wistar Albino rats at the age of 50–100 days. The uterine acetyl cholinesterase enzyme was significantly increased in the treated animals compared to that in the controls. Therefore, zearalenone would be considered as an esterogenic effector for increasing the uterine acetyl cholinesterase which enhances uterine relaxation and subsequently improves its function for pregnancy in prematured-animals.Unlike estradiol, it was interesting to find that the estrogenicity of zearalenone was increased by the moderating progesterone hormone. Moreover, it was revealed in this study that the injected dose of zearalenone had no deleterious effects on the pregnant rats at 10–12 days period of gestation. The harmful effects of zearalenone on pregnant animals cited in the literature (11, 13, 19) were reviewed. 相似文献
3.
B A Nassar Y S Huang A T McDonald K D Jenkins D F Horrobin 《Canadian journal of physiology and pharmacology》1988,66(9):1206-1209
We investigated the effects of phenelzine and tranylcypromine on the release of prostacyclin, thromboxane A2, prostaglandin E2, and prostaglandin E1 from the isolated perfused rat mesenteric vascular bed. Perfusion of the preparation with phenelzine in concentrations of 15, 45, and 135 microM for 150 min led to attenuated release of all four prostaglandins measured. Inhibition generally occurred with the lowest dose used and was most prominent with the highest concentration. Tranylcypromine also decreased prostaglandin formation. However, low doses were not effective in the suppression of prostacyclin release. Both drugs had an inhibitory effect on production of prostaglandin E1, which is a metabolite of dihomo-gamma-linolenic acid, the precursor of arachidonic acid, but this was only shown to be significant with phenelzine. In this work we demonstrate that phenelzine and tranylcypromine have an inhibitory effect on the production of 2-series prostaglandins derived from arachidonic acid, and possibly a similar effect on prostaglandins of the 1-series derived from dihomo-gamma-linolenic acid. 相似文献
4.
5.
Summary The transport of taurine across adult Sprague-Dawley rat small intestine was studied in vitro using small intestinal strips. The kinetics of the transport mechanism were investigated under both steady-state and influx conditions. Our findings were compatible with the presence of two distinct transport mechanisms; a linear non-carrier mediated component and a saturable carrier mediated component, with almost equal contribution from each. The mediated component was found to be largely Na+-dependent and exhibited marked inhibition by B-alanine and structurally related sulfur amino acids. 相似文献
6.
Nassar NM 《Genetics and molecular research : GMR》2002,1(2):147-152
Apomixis means seed formation without fertilization. In cassava (Manihot esculenta) it is an alternative to reproduction by cuttings, which normally transmits pathogens and leads to an accumulation of viral and bacterial diseases. Apomixis also assures preservation of heterosis and avoids genetic segregation. It occurs in wild relatives of cassava and has been transferred successfully from Manihot glaziovii and M. neusana. It is facultative, and occurs at a low frequency, ranging from 1-2%, and apparently is genetically different from apomixis in other crops. With selection, the frequency can reach 13%. Apomixis in cassava is frequently associated with aneuploidy but it does occur in some diploid types. It is due to the formation of aposporic sacs, which can easily be detected by clearing tissue preparations. Apomixis appears to have played an important role in speciation during the evolution of Manihot, since it leads to the maintenance and perpetuation of sterile interspecific hybridization. The use of apomixis in cassava breeding could lead to a boom in line improvement and commercial production. In addition to preserving superior genotypes, avoiding contamination of new plants, it would enable international programs to export their germplasm to destination countries. This would allow the use of superior genotypes even if apomixis occurs at a low frequency. A scheme to maximize benefits is to use diploid apomictic clones as maternal parents, which can be crossed with pollinators of polyploid interspecific hybrids, followed by selection among the progeny of new apomictic types that combine the heteroses of both interspecific hybridization and polyploidy. In addition, they acquire favored genes that have been transferred from the wild to the commercial crop. 相似文献
7.
Tamir K. Nassar Marietta Issidorides William M. Shanklin 《Biotechnic & histochemistry》1960,35(1):15-18
Representative pieces of human brain were fixed in 10% formalin, embedded in paraffin and sectioned at 5 μ. Paired sections were used, one of which was oxidized in equal parts of 0.5% potassium permanganate and 0.5% sulfuric acid for 1-2 min, while the other was left unoxidized. Both the oxidized and unoxidized sections were impregnated with silver diamine. The lipofuscin granules in the nerve cells appeared as small intensely stained black dots, surrounded by a clear unstained zone, in the unoxidized sections, while in the oxidized sections there was an outer ring of intensely blackened material surrounding a central unstained dot. 相似文献
8.
Pieces of brain are fixed in formalin ammonium bromide for about 4 days at room temperature, and given the following treatment: After washing, dehydrating and clearing, embed in paraffin, section and mount. Deparaffinize sections and pass through graded alcohols to water. Sensitize in 5% sodium sulfite for 2 hours, wash in distilled water and impregnate with silver diamminohydroxide solution 2-5 minutes at room temperature. Reduce in 2% formalin, wash in distilled water and tone in gold chloride. Fix in 5% hypo, counterstain with 1% picric acid, dehydrate and cover in balsam. Equally good results are obtained by impregnating with Hortega's strong silver carbonate. The microglia, oligodendroglia, fibrous and protoplasmic astrocytes in the cat, rabbit, newborn and adult human are successfully stained by this method. 相似文献
9.
This work was conducted in order to study the kinetic behaviour of dietary aflatoxins in the colostrum of a pregnant cow exposed to contaminated feeds for a short period.In this study, two pregnant cows received a single dose of dietary aflatoxins in the form of rice powder contained 31.20 ppm aflatoxin B and 19.68 ppm aflatoxin G during the last stage of pregnancy, at about two weeks before parturition.Samples of colostrum were collected from dams and assayed for the presence of toxic metabolites as well as its conjugations by electrophoretic analysis.The results revealed that the intake of aflatoxins appeared in the colostrum pospartum as AFM1 and also AFB2a which is a non toxic metabolite. Moreover, it was found that the excreted metabolites including AFB2a were conjugated to the immunoglobulin protein fraction of the colostrum.The significance of the obtained results to the newborn calf are discussed. 相似文献
10.
Alejandro A. Pezzulo Patrick H. Kelly Boulos S. Nassar Cedric J. Rutland Nicholas D. Gansemer Cassie L. Dohrn Andrew J. Costello David A. Stoltz Joseph Zabner 《Applied and environmental microbiology》2013,79(19):5936-5941
Human lungs are constantly exposed to bacteria in the environment, yet the prevailing dogma is that healthy lungs are sterile. DNA sequencing-based studies of pulmonary bacterial diversity challenge this notion. However, DNA-based microbial analysis currently fails to distinguish between DNA from live bacteria and that from bacteria that have been killed by lung immune mechanisms, potentially causing overestimation of bacterial abundance and diversity. We investigated whether bacterial DNA recovered from lungs represents live or dead bacteria in bronchoalveolar lavage (BAL) fluid and lung samples in young healthy pigs. Live bacterial DNA was DNase I resistant and became DNase I sensitive upon human antimicrobial-mediated killing in vitro. We determined live and total bacterial DNA loads in porcine BAL fluid and lung tissue by comparing DNase I-treated versus untreated samples. In contrast to the case for BAL fluid, we were unable to culture bacteria from most lung homogenates. Surprisingly, total bacterial DNA was abundant in both BAL fluid and lung homogenates. In BAL fluid, 63% was DNase I sensitive. In 6 out of 11 lung homogenates, all bacterial DNA was DNase I sensitive, suggesting a predominance of dead bacteria; in the remaining homogenates, 94% was DNase I sensitive, and bacterial diversity determined by 16S rRNA gene sequencing was similar in DNase I-treated and untreated samples. Healthy pig lungs are mostly sterile yet contain abundant DNase I-sensitive DNA from inhaled and aspirated bacteria killed by pulmonary host defense mechanisms. This approach and conceptual framework will improve analysis of the lung microbiome in disease. 相似文献