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1.
[3H]Pteroylglutamic acid (PteGlu) uptake was studied using brush-border membrane vesicles isolated from rat kidney. Results on the uptake of [3H]PteGlu by brush-border membrane vesicles incubated in media of increasing osmolarities demonstrated that uptake was contributed by two components, intravesicular transport and membrane binding. Both the components of the uptake exhibited similar pH dependence, with maxima at pH 5.6, and were found to be saturable mechanisms with Km values of 6.7.10(-7) and 11.2.10(-7) M, respectively. These studies show that PteGlu is transported by isolated rat kidney brush-border membrane vesicles in a manner consistent with a saturable system and that a binding component may be functionally associated with this. 相似文献
2.
Y K Gupta P Bhandari A Chugh S D Seth K S Dixit K P Bhargava 《Indian journal of experimental biology》1989,27(1):52-54
The role of opioid and histaminergic system in morphine induced emesis was investigated in dogs. Morphine (25 micrograms, icv) consistently evoked emesis with an average latency of 195 +/- 29 sec which was fully accounted for by an action on the chemoreceptor trigger zone (CTZ) as its ablation rendered animals refractory to vomiting. Intraventricular pretreatment with opioid antagonist naloxone, histamine H1 antagonist mepyramine and H2 antagonists metiamide and cimetidine afforded protection to icv morphine emesis. The CSF histamine concentration was significantly raised 5 min after icv morphine administration. The results suggest that both endogenous opioid and histamine are involved in morphine emesis. Naloxone in high doses (1600 micrograms, icv) elicited emesis which was not blocked by CTZ ablation confirming our earlier report. 相似文献
3.
High level of divergence of male-reproductive-tract proteins, between Drosophila melanogaster and its sibling species, D. simulans 总被引:1,自引:0,他引:1
We compared male-reproductive-tract polypeptides of Drosophila melanogaster
and D. simulans by using two-dimensional gel electrophoresis. Approximately
64% of male-reproductive-tract polypeptides were identical between two
randomly chosen isofemale lines from these two species, compared with 83%
identity for third-instar imaginal wing-disc polypeptides. Qualitatively
similar differences were found between reproductive tracts and imaginal
discs when D. sechellia was compared with D. melanogaster and with D.
simulans. When genic polymorphism was taken into account, approximately 10%
of male- reproductive-tract polypeptides were apparently fixed for
different alleles between D. melanogaster and D. simulans; this proportion
is the same as that found for soluble enzymes by one-dimensional gel
electrophoresis. Strikingly, approximately 20% of male-reproductive- tract
polypeptides of either D. melanogaster or D. simulans had no detectable
homologue in the other species. We propose that proteins of the Drosophila
male reproductive tract may have diverged more extensively between species
than have other types of proteins and that much of this divergence may
involve large changes in levels of polypeptide expression.
相似文献
4.
Analysis by 1H-NMR spectroscopic techniques of the conformation of the N-terminal segment of the LC1 alkali light chain of rabbit skeletal muscle has shown that this portion of the molecule adopts a well-defined elongated configuration. This rod-like feature is a consequence of the Ala/Pro-rich composition and the functional aspects of such conformational preference in this and similar segments in other proteins are discussed. 相似文献
5.
A spontaneous ameloblastic odontoma was found in an 86-week-old male Fischer 344 rat. Radiographic and histopathologic characteristics confirmed the diagnosis as a true benign neoplasm. 相似文献
6.
Ambikesh Soni Manohar Prasad Bhandari Gagan Kant Tripathi Priyavand Bundela Pradeep Kumar Khiriya Purnima Swarup Khare Manoj Kumar Kashyap Abhijit Dey Balachandar Vellingiri Suresh Sundaramurthy Arisutha Suresh José M. Pérez de la Lastra 《Journal of cellular and molecular medicine》2023,27(6):737-762
In recent years, drug manufacturers and researchers have begun to consider the nanobiotechnology approach to improve the drug delivery system for tumour and cancer diseases. In this article, we review current strategies to improve tumour and cancer drug delivery, which mainly focuses on sustaining biocompatibility, biodistribution, and active targeting. The conventional therapy using cornerstone drugs such as fludarabine, cisplatin etoposide, and paclitaxel has its own challenges especially not being able to discriminate between tumour versus normal cells which eventually led to toxicity and side effects in the patients. In contrast to the conventional approach, nanoparticle-based drug delivery provides target-specific delivery and controlled release of the drug, which provides a better therapeutic window for treatment options by focusing on the eradication of diseased cells via active targeting and sparing normal cells via passive targeting. Additionally, treatment of tumours associated with the brain is hampered by the impermeability of the blood–brain barriers to the drugs, which eventually led to poor survival in the patients. Nanoparticle-based therapy offers superior delivery of drugs to the target by breaching the blood–brain barriers. Herein, we provide an overview of the properties of nanoparticles that are crucial for nanotechnology applications. We address the potential future applications of nanobiotechnology targeting specific or desired areas. In particular, the use of nanomaterials, biostructures, and drug delivery methods for the targeted treatment of tumours and cancer are explored. 相似文献
7.
Nitrate, nitrite and nitrous oxide were denitrified to N2 gas by washed cells ofRhizobium japonicum CC706 as well as by bacteroids prepared from root nodules ofGlycine max (L.) Merr. (CV. Clark 63). Radiolabelled N2 was produced from either K15NO3 or Na15NO2 by washed cells ofRh. japonicum CC705 grown with either nitrate only (5 mM) or nitrate (5 mM) plus glutamate (10 mM). Nitrogen gas was also produced from N2O. Similar results were obtained with bacteroids ofG. max. The stoichiometry for the utilization of15NO
3
-
or15NO
2
-
and the produciton of15N2 was 2:1 and for N2O utilization and N2 production it was 1:1. Some of the15N2 gas produced by denitrification of15NO
3
-
in bacteroids was recycled via nitrogenase into cell nitrogen. 相似文献
8.
RS Fisher 《The Journal of general physiology》1977,69(5):571-604
When the outer surface of short-circuited frog skin was penetrated with microelectrodes, stable negative potentials that averaged near -100 mV were recorded consistently, confirming the results of Nagel (W. Nagel. 1975. Abstracts of the 5th International Biophysics Congress, Copenhagen. P-147.). The appearance of these stable potentials, V(O), concurrent with the observations that (a) a high resistance outer barrier R(O) accounting for approximately 75 percent or more of the transcellular resistance of control skins had been penetrated and that (b) 10(-5) M amiloride and reduced [Na] outside caused the values of V(O) to increase towards means value near -130 mV while the values of percent R(O) increased to more than 90 percent. It was of relationships were the same as the values of E(1) observed in studies of the current-voltage relationships were the same as the values of E’(1) defined as the values of voltage at the inner barrier when the V(O) of the outer barrier was reduced to zero by voltage clamping of the skins. Accordingly, these data are interpreted to mean that the values of E(1), approximately 130 mV, represent the E(Na) of the sodium pump at the inner barrier. 2,4-DNP was observed to decrease the values of transepithelial voltage less than E(1) the V(O) was negative. These data can be interpreted with a simple electrical equivalent circuit of the active sodium transport pathway of the frog skin that includes the idea that the outer membrane behaves as an electrical rectifier for ion transport. 相似文献
9.
The technique of fluorescence quenching by the non-ionic quenchers acrylamide and nicotinamide has been used to probe the accessibility of the environmentally sensitive N-(bromoacetyl)-N'-(1-sulpho-5-naphthyl) ethylenediamine (1,5-Br-AEDANS) fluorophore attached to either Cys-177 of the A1-light chain or the SH1 thiol (Cys-707) of the myosin subfragment (S1) heavy chain. Neither quencher caused any detrimental effects to the ATPase activities of S1 under the conditions of the experiments. It was found that the fluorophore on the isolated light chain was highly exposed to solvent and although this exposure was reduced on hybridization into S1(A1-AEDANS), the probe was still accessible to solvent. This exposure was unaltered by formation of binary complexes with either Mg.ATP or actin or by the formation of a weakly associated acto-S1 complex (in which the Cys-697 and Cys-707 residues of S1 were crosslinked with p-phenylenedimaleimide). The lack of corresponding change in lambda max of emission and quantum yield supported the quenching date and indicated that actin neither binds directly to this region nor induces any significant conformational changes in this locality despite the observation that the A1-Cys-707 moves some 3 nm closer to a point on actin in the weak-binding state (Trayer, H.R. and Trayer, I.P. (1988) Biochemistry, 27, 5718-5727). Parallel experiments with the fluorophore attached to the Cys-707 of the S1 indicated that this region was less accessible to solvent than the light chain thiol despite its ease of labelling. This exposure was not significantly altered by binary complex formation with actin and Mg.ATP, although spectral changes in the absence of quencher support the notion that some conformational change is occurring in this region. 相似文献
10.
A new furanobicoumarin rhamnoside has been characterized from the whole plant extract of Lasiosiphon eriocephalus. 相似文献