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991.
M Ia Ratner M A Brodski? M L Zubkin I I Stenina I M Slutskin 《Terapevticheski? arkhiv》1991,63(6):12-15
Tubulointerstitial alterations associated with chronic glomerulonephritis (CGN) are definitely dependent on the clinical type of CGN and are accompanied by a decrease of homeostatic functions (the rate of glomerular filtration, osmotic concentration and dilution of urine, hydruresis, the magnitude of CH2O, excretion of ammonium and hydrogen ions, the ratio of ammonium excretion to hydrogen ion excretion). Maximal osmotic concentration and ammonium excretion show an especially considerable decrease. The clinical type permitting one to diagnose rather than to reject the presence of alterations and the status of certain tubular functions, osmotic concentration in particular and, to a less degree, ammonium excretion, permitting to reject the presence of the tubulointerstitial component (TIC) are of known but restricted importance for TIC recognition. The TIC can be diagnosed more adequately in exploring definite pairs of renal functions, particularly osmotic concentration of urine and ammonium excretion and maximal hydruresis and excretion of hydrogen ions. This approach is both helpful in confirming and rejecting the presence of the TIC. Of special value is the combined assessment of the clinical type and maximal osmotic urine concentration data. 相似文献
992.
Zia Hossein Ma Joseph K. H. O'Donnell John P. Luzzi Louis A. 《Pharmaceutical research》1991,8(4):502-504
Dimethyl isosorbide (DMI), which is currently under investigation for its potential use as a pharmaceutical vehicle and drug permeation enhancer, is a water-miscible liquid with relatively low viscosity. The solubilization behavior of DMI as a cosolvent for nonpolar drugs was characterized via dielectric constant measurements of binary solvent systems containing DMI and either water, propylene glycol (PG), or polyethylene glycol (PEG). Evidence from the dielectric constant profiles and NMR studies suggest that DMI undergoes complexation with water and PG, but not with PEG, through hydrogen bonding interactions. The solvent complexation exhibited a major effect on the solubilities of prednisone, dexamethasone, and prednisolone in the mixed solvent systems. Maximum solubility of each drug was found to occur near a DMI/water or DMI/PG concentration ratio of 1:2. In the DMI–PEG mixed system, while there is no apparent interaction between DMI and PEG molecules, the solubility of prednisone was found to increase with decreasing dielectric constant. 相似文献
993.
994.
Cloning and characterization of Ca(2+)-dependent and Ca(2+)-independent PKCs expressed in Aplysia sensory cells 总被引:2,自引:0,他引:2
K E Kruger W S Sossin T C Sacktor P J Bergold S Beushausen J H Schwartz 《The Journal of neuroscience》1991,11(8):2303-2313
We isolated cDNA clones from an Aplysia sensory-cell library encoding two isoforms of protein kinase C (PKC). Several isozyme-specific regions are conserved in the Aplysia kinases, notably the variable regions V5 in the Ca(2+)-dependent PKC (Apl I) and V1 in the Ca(2+)-independent PKC (Apl II). Neuronal proteins with the properties expected of these two isoforms can be identified with antibodies raised against peptides synthesized from the amino acid sequences deduced from the clones. Sacktor and Schwartz (1990) measured the proportion of kinase activity that can be translocated to membrane in Aplysia sensory neurons and ganglia by stimuli that produce the presynaptic facilitation underlying behavioral sensitization. Much less Apl I and Apl II are translocated, suggesting that still other isoforms of PKC exist in these cells. 相似文献
995.
J M Darby E M Nemoto H Yonas J Melick 《Journal of cerebral blood flow and metabolism》1991,11(3):522-526
Stable xenon (Xe)-enhanced computed tomography is a potentially valuable tool for high resolution, three-dimensional measurement of CBF in patients. However, reports that Xe causes cerebrovascular dilation and increases intracranial pressure (ICP) have tempered enthusiasm for its use. The effects of 5 min of 33% Xe inhalation on ICP (right and left hemispheres) were studied in eight fentanyl-anesthetized Rhesus monkeys after right-sided cortical freeze injury. ICP, CBF, and physiological variables were monitored for up to 6 h postinsult. The preinjury (control) right hemispheric ICP was 8 +/- 5 mm Hg (mean +/- SD) and left hemispheric ICP was 5 +/- 2 mm Hg. Postinjury observations were classified into low (less than 15 mm Hg) and high ICP (greater than or equal to 15 mm Hg) groups. Both right and left ICP values averaged 9 +/- 3 mm Hg in the low ICP group. In the high ICP group, the right ICP was 20 +/- 4 mm Hg and left ICP was 21 +/- 6 mm Hg. ICP was unchanged by Xe inhalation under control conditions as well as in both low and high ICP groups postinjury. Postinjury, the MABP decreased 10-15 mm Hg in the low ICP group and 10-17 mm Hg in the high ICP group 2-3 min after the start of Xe inhalation (p less than 0.05). These results show that 33% Xe inhalation does not increase ICP in fentanyl-anesthetized monkeys but could decrease MABP in stressed states, presumably because of the anesthetic effects of Xe. 相似文献
996.
M A Warner K H Neill J V Nadler B J Crain 《Journal of cerebral blood flow and metabolism》1991,11(4):600-610
This study compared the ability of three N-methyl-D-aspartate (NMDA) receptor antagonists to prevent neuronal degeneration in an animal model of global cerebral ischemia. The model employed is characterized by damage to the striatum, hippocampus, and neocortex. Antagonists were administered to gerbils either before or after a 5-min bilateral carotid occlusion. The intraischemic rectal temperature was either maintained at 36-37 degrees C or allowed to fall passively to 28-32 degrees C. Antagonists and doses tested were 1 and 10 mg/kg of MK-801 (pre- or postischemia), 30 mg/kg of CGS 19755 preischemia, four 25 mg/kg doses of CGS 19755 administered between 0.5 and 6.5 h postischemia, and 40 mg/kg of MDL 27,266 (pre- or postischemia). All three NMDA receptor antagonists exhibited some degree of neuroprotective activity when the carotid occlusion was performed under normothermic conditions. Most of the treatments with antagonist markedly reduced striatal damage. CA1 hippocampal and neocortical pyramidal cells were spared by only three of the treatments, however, and the extent of neuroprotection varied widely from case to case. Toxic doses of antagonist were required to protect CA1 pyramidal cells from ischemic damage. Ischemic damage to hippocampal areas CA2-CA3a and CA4 appeared to be resistant to all of these treatments. Most CA1 pyramidal cells that were protected from degeneration by an NMDA receptor antagonist were histologically abnormal. The neuroprotective effects of MK-801 and intraischemic hypothermia appeared to be additive. MK-801 (10 mg/kg) consistently reduced the postischemic brain temperature, but only the magnitude of hypothermia produced soon after reperfusion correlated with its neuroprotective action. These results suggest that NMDA receptor antagonists are relatively poor neuroprotective agents against a moderately severe ischemic insult. 相似文献
997.
A new in vivo model for studying brain metabolic and haemodynamic oscillatory phenomena during ischaemia is described. In this model acute or chronic occlusion of one or two carotid arteries in the rat is performed. Due to the partial ischaemia developed, oscillations in the level of intramitochondrial pyridine nucleotides (NADH) as well as flavoproteins (Fp) were recorded from the brain by monitoring the fluorescence of these respiratory chain components. The two fluorescent signals (NADH and Fp) were measured by using the time sharing or DC fluorometer/reflectometer. The changes in the reflected light at the excitation wavelengths (366 and 450 nm) were recorded simultaneously. Bilateral carotid artery occlusion induced immediate oscillations (6-9 waves per min) in the mitochondrial redox state as well as in tissue blood volume in both hemispheres. To verify the accuracy of the NADH monitoring system, including the correction technique for haemodynamic and other artifacts, we used the intracarotid artery saline bolus injection approach. The results could be summarized as follows: (1) unilateral carotid artery occlusion resulted in delayed development of oscillations, particularly in the ipsilateral hemisphere; (2) the oscillation phenomenon was reversible if recirculation restarted within 5 min. Occlusion for more than 30 min resulted in irreversible oscillations; (3) the oscillation appearances and intensities were affected by various physiological conditions. Vasoconstriction, induced by hyperoxia, stimulated the oscillations while vasodilation, induced by hypercapnia, depressed them. Anoxia, hypoxia and spreading depression (SD) abolished the oscillations. Glucose injection was not effective.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
998.
The effects of maternal ethanol exposure on neurotransmission and second messenger systems were examined in rats using histochemistry and in vitro autoradiography. Thirty % ethanol was administered to pregnant rats from gestational day 7 to the day of delivery. Quantitative autoradiography was used to map muscarinic cholinergic, dopamine D2, adenosine A1, and inositol 1,4,5-trisphosphate binding sites, as well as to localize adenylate cyclase and protein kinase C. We found no difference in the patterns of staining with acetylcholinesterase and Timm's stain between control and prenatally ethanol-exposed rats on postnatal day (PN) 30. In the ethanol-exposed rats, [3H]forskolin binding sites were increased during early development in the CA1 subfield of the hippocampus and the occipital cortex; [3H]phorbol ester binding sites were increased in the cortex, striatum, and hippocampus; hippocampal muscarinic cholinergic sites were increased on PN4 and 30; adenosine A1 binding was reduced on PN10 in most regions examined, but was increased in the CA1 subfield on PN30; dopamine D2 receptor levels were significantly reduced on PN30 in the striatum; and IP3 receptors were decreased in most regions studied, but particularly in the cerebellum. Thus, some of these changes were transient and others were long-lasting. Although histopathological abnormalities were minimal, the alterations of binding sites in the cerebellum (the coordination center) and in the hippocampus (related to memory and learning) that were detected may contribute to the behavioral and mental deterioration seen in the fetal alcohol syndrome. 相似文献
999.
The possibility was investigated that specific opioid receptor types might selectively alter the production of isolation-induced ultrasonic vocalizations. Intracisternal injections of mu, delta and kappa opioid receptor agonists were administered to isolated 10-day-old rat pups. The mu receptor agonist [D-Ala2-NMe-Phe4-Gly-ol]-enkephalin (DAMGO) and delta receptor agonist [D-Pen2, D-Pen5]-enkephalin (DPDPE) both reduced the rate of isolation-induced ultrasonic calling in the absence of sedation. The kappa receptor agonist U50,488 had the opposite effect, significantly raising the rate of vocalization. Fourteen-day-old pups, with a larger delta receptor population, showed a greater sensitivity to DPDPE than was seen in the younger animals. 相似文献
1000.
Methylmercury induced alterations in the nerve growth factor level in the developing brain. 总被引:1,自引:0,他引:1
L L?rkfors A Oskarsson J Sundberg T Ebendal 《Brain research. Developmental brain research》1991,62(2):287-291
Pre- and early postnatal stages in the development of the central nervous system (CNS) are very sensitive to the toxic effects of methylmercury. The influence of methylmercury on the level of nerve growth factor (NGF) during the development of CNS was studied. Sprague-Dawley rats were exposed indirectly throughout the fetal and suckling periods until weaning on postnatal day 25 (P 25) via their dams given methylmercury in the diet (3.9 mg/kg diet). In addition, after weaning offsprings were exposed directly to methylmercury via the diet until postnatal day 50 (P 50). The level of NGF was analyzed in cortical areas and in the septum with a sensitive enzyme immunoassay. The pups exposed to MeHg exhibited a 50% elevation in the level of NGF in the hippocampus on P 25 and P 50 compared to control animals. Concomitantly, the level of NGF decreased by 30% in the septum on P 25 and P 50, suggesting that the retrograde transport of NGF from hippocampus to septum could be affected by the exposure of methylmercury. The exact mechanism by which the low level of mercury is affecting the NGF concentration in the developing brain is yet unknown. The increase of NGF in the hippocampus and the decrease of NGF measured in the septum could reflect altered conditions for neurotrophic support in these areas of the brain as a result of the exposure to heavy metal. Thus, this finding might indicate a connection between exposure of heavy metals and neurodegeneration, such as that found in the basal forebrain in Alzheimer's disease. 相似文献