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A J Li

Publications and source records attributed to A J Li.

29 records · Page 2Linked to original sources
PubMed1993

Memory facilitation educed by food intake.

Acidic fibroblast growth factor (aFGF) in rat CSF increased 1000 times in the 2-h period after food intake, or IP, or ICV glucose infusion. The ICV application of aFGF dose dependently depresses and anti-aFGF antibody facilitates food intake. aFGF is produced in the ependymal cells and released into the CSF in response to increased glucose in the CSF caused by food intake. Released aFGF diffused into the brain parenchyma and was taken up into neurons in the hypothalamus, hippocampus, amygdala, etc. IP injection of glucose 2 h before a task that combined acquisition with passive avoidance significantly increased retention of avoidance by mice tested 24 h later. In a Morris water maze task, IP glucose injection 2 h before a first trial block reduced time to find and climb onto a platform hidden just below the water surface. The glucose facilitation of these affective and spatial memory were abolished by pretreatment with anti-aFGF antibody applied ICV. Continuous ICV infusion of aFGF into rats also significantly increased the reliability of passive avoidance for several days. After food intake, centrally released aFGF reaches the hippocampus and facilitates memory; peripherally released cholecystokinin reaches the endings of the afferent vagal nerves in the portal vein and changes their activity, which modulates hippocampal activity, to lead to memory facilitation. This, however, is blocked by vagotomy below the diaphragm. The results indicate the importance of food intake, not only to maintain homeostasis, but also to prepare a readiness state for memory facilitation.

Afferent Pathways↗
PubMed1993

Evaluation of truncated readout-echo MR images obtained at 0.35 T.

It is possible to acquire a truncated echo, in which part of the information at the beginning or end of the echo is missing, and to restore the missing information by conjugation. This process was shown by means of edge spread function in phantoms and brain images in volunteers to introduce little, if any, degradation of image quality and can be used to improve sequence efficiency or to shorten echo time.

Brain↗
PubMed1992

A new brain glucosensor and its physiological significance.

The concentration of fibroblast growth factor (FGF), which is found in cerebrospinal fluid (CSF), markedly increases after the start of feeding. Food intake was dose-dependently suppressed by picomole doses of FGF and facilitated by anti-FGF antibody. This suppression was caused by activation of protein kinase C in glucose-sensitive neurons in the lateral hypothalamus. In situ hybridization by use of cDNA showed that acidic (a)FGF was produced in ependymal cells. The ependymal cells released aFGF by responding to glucose increase in CSF after feeding. Released aFGF diffused into the brain parenchyma and was taken by neurons. Passive avoidance was significantly more reliable after aFGF infusion into CSF. Clamping cerebral arteries in the gerbil induced ischemia, which damaged neurons in the CA1 layer of the hippocampus. Pretreatment with aFGF prevented this damage. Thus, aFGF is not only the most potent substance yet found for the suppression of feeding, but it is also extremely effective as a neurotrophic and memory facilitating substance.

Animals↗
PubMed1992

Impact of section doubling on MR angiography.

To improve the quality of projection angiograms generated from three-dimensional magnetic resonance (MR) angiography data, the authors applied voxel shifting to create intermediate sections ("section doubling") prior to maximum intensity projection. To date, the authors have processed MR angiography studies with and without section doubling in 20 cases. Section doubling resulted in improved vessel contrast and delineation of continuity (especially of small vessels) in all cases.

Blood Vessels↗
PubMed1990

[Construction and application of atropine flow-through sensor in flow injection analysis].

A new kind of flow-through sensor for atropine has been studied. It exhibits Nernstian response for atropine with a slope of 54 +/- 1 mV/decade over the concentration range of 0.02-200 mmol/L at pH 5-8. The sensitivity coefficients of common compounds were determined. Only bromo-geramine, clonidine, strychnine and amantadine showed remarkable interference. Direct potentiometry for determination of atropine showed an average recovery of 99.2% and a relative standard deviation of 1.3%. It has been used in flow injection analysis (FIA) of atropine, anisodamine and scopolamine and belladonna preparations. Rate of analysis of as high as 60-100 samples/h was achieved.

Atropa belladonna↗
PubMedDate not supplied

Effect of acidic fibroblast growth factor on basal forebrain cholinergic neurons in senescence-accelerated mice.

We examined the effects of chronic administration of acidic fibroblast growth factor (aFGF) on memory and choline acetyltransferase (ChAT) immunoreactivity in the forebrain of senescence-accelerated mice (SAMP8 strain). Subcutaneous injection of aFGF (aFGF group) or saline vehicle (saline group) once a week into SAMP8 was begun at three weeks after birth and continued for nine months. In the passive avoidance test, the retained latency was significantly longer in the aFGF group than in the saline group. In the Morris test, the mean latency to climb on a platform was significantly shorter in the aFGF group than in the saline group. The number of ChAT-positive neurons in the forebrain septum was greater in the aFGF group than in the saline group, and was at the level of that in the control mouse strain (SAMR1). The intensity of ChAT staining in the aFGF group appeared slightly weaker than in SAMR1 but significantly stronger than in the saline group. The results indicate that the effect of aFGF on memory function in SAMP8 may be related to the preservation of function in septal cholinergic cells.

Aging↗
PubMedDate not supplied

The use of continuous infusion topotecan in persistent and recurrent ovarian cancer.

We retrospectively review our experience with continuous infusion topotecan for the treatment of persistent or recurrent ovarian cancer in this paper. Nine patients were identified who were treated at the University of California Los Angeles Medical Center between January 1997 and December 1999 using a 14-21 day continuous infusion schedule (0.3-0.7 mg/m2/d). Dose adjustments were performed for grade 3-4 toxicities and treatment was discontinued for persistent severe toxicity or progressive disease. Response to treatment was analyzed and stratified by platinum refractory, resistant, and sensitive disease. A total of 41 treatment cycles were given to nine patients with a median of five per patient (range 1-11). Median follow-up was 8 months. There were two partial responses (22%) and four patients had stable disease (44%), which included two patients with platinum-refractory tumors. No grade 3 or 4 hematologic toxicities were observed. However, two patients suffered grade 3 gastrointestinal toxicity during the first cycle leading to discontinuation of topotecan administration. There was no cumulative toxicity. Topotecan administered by continuous infusion demonstrated response rates comparable to other dosing schedules with minimal hematologic toxicity. Treatment of patients with persistent or recurrent ovarian cancer with continuous infusion topotecan warrants further investigation.

Aged↗
PubMedDate not supplied

Impairment of spatial learning and hippocampal synaptic potentiation in c-kit mutant rats.

The c-kit receptor tyrosine kinase encoded by the white-spotting (W) gene is highly expressed in rat hippocampal CA1-CA4 regions. We found an impaired spatial learning and memory in homozygous c-kit (Ws/Ws) mutant rats that have a 12-base deletion in the tyrosine kinase domain of the c-kit gene and a very low kinase activity. Electrophysiological studies in hippocampal slices revealed that the long-term potentiation (LTP) induced by the tetanic stimulation (100 Hz, 1 sec) in the mossy fiber (MF)-CA3 pathway, but not in the Schaffer collaterals/commissural-CA1 pathway, was significantly reduced in c-kit mutants compared with wild-type (+/+) rats. The paired-pulse facilitation (PPF) was measured before the tetanus and after the establishment of the LTP in each slice. The initial PPF in the MF-CA3 pathway positively correlated with the amplitude of the LTP in the wild-type rats but not in the c-kit mutant rats. Furthermore, they failed to show the normal characteristics observed in the MF-CA3 pathway of +/+ rats; that is, the negative correlation between the initial PPF and the changes in PPF measured after the LTP. These findings suggest an involvement of SCF/c-kit signaling in hippocampal synaptic potentiation and spatial learning and memory.

Animals↗