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Biomedical subjects

X Y Lu

Publications and source records attributed to X Y Lu.

At least 19 recordsLinked to original sources
PubMed2003

Production of poly(3-hydroxybutyrate- co-3-hydroxyhexanoate) with flexible 3-hydroxyhexanoate content in Aeromonas hydrophila CGMCC 0911.

Aeromonas hydrophila CGMCC 0911 isolated from lake water was found to be able to synthesize a polyhydroxyalkanoate (PHA) copolymer (PHBHHx) consisting of 3-hydroxybutyrate (HB) and 4-6 mol% 3-hydroxyhexanoate (HHx). The wild-type bacterium accumulated 49% PHBHHx containing 6 mol% HHx in terms of cell dry weight (CDW) when grown on lauric acid for 48 h. When A. hydrophila CGMCC 0911 expressed the Acyl-CoA dehydrogenase gene ( yafH) of Escherichia coli, the recombinant strain could accumulate 47% PHBHHx, while the HHx content reached 17.4 mol%. The presence of changing glucose concentration in the culture changed the HHx content both in wild type and recombinant A. hydrophila CGMCC 0911. When 5 g l(-1) glucose was added to a culture containing 5 g l(-1) lauric acid as co-substrate, 45% PHBHHx/CDW consisting of 8.8 mol% HHx was produced by wild-type A. hydrophila CGMCC 0911 compared with only 5% in the absence of glucose. When the recombinant A. hydrophila CGMCC 0911 was grown on a mixed substrate containing lauric acid and 8-10 g l(-1) glucose, the HHx content could be further increased to 35.6 mol%. When the glucose concentration exceeded 10 g l(-1), cell growth, PHA content and mole percentages of HHx in PHBHHx were significantly reduced.

3-Hydroxybutyric Acid↗
PubMed2002

The utility of spectral karyotyping in the cytogenetic analysis of newly diagnosed pediatric acute lymphoblastic leukemia.

We applied multicolor spectral karyotyping (SKY) to a panel of 29 newly diagnosed pediatric pre B-cell ALLs with normal and abnormal G-banded karyotypes to identify cryptic translocations and define complex chromosomal rearrangements. By this method, it was possible to define all add chromosomes in six cases, a cryptic t(12;21)(p13;q11) translocation in six cases, marker chromosomes in two cases and refine the misidentified aberrations by G-banding in two cases. In addition, we identified five novel non-recurrent translocations - t(2;9)(p11.2;p13), t(2;22) (p11.2;q11.2), t(6;8)(p12;p11), t(12;14)(p13;q32) and t(X;8)(p22.3;q?). Of these translocations, t(2;9), t(2;22) and t(12;14) were identified by G-banding analysis and confirmed by SKY. We characterized a t(12;14)( p13;q32) translocation by FISH, and identified a fusion of TEL with IGH for the first time in ALL. We identified a rearrangement of PAX5 locus in a case with t(2;9)(p11.2;p13) by FISH and defined the breakpoint telomeric to PAX5 in der(9)t(3;9)(?;p13). These studies demonstrate the utility of using SKY in combination with G-banding and FISH to augment the precision with which chromosomal aberrations may be identified in tumor cells.

Acute Disease↗
PubMed2001

Time course of short-term and long-term orexigenic effects of Agouti-related protein (86-132).

Agouti-related protein (AGRP) is a newly identified orexigenic peptide that acts as an endogenous antagonist of melanocortin receptors MC3 and MC4. The present study examined the time course of the orexigenic effects of synthetic AGRP (86-132). Intracerebroventricular infusion of 0.1 nmol AGRP (86-132) increased food intake by 450 +/- 81% at 2 h post-injection. A second increase in non-cumulative food intake (512 +/- 135%) was observed at 6 h post-injection. Following a single dose of AGRP (86-132) (0.1 nmol) the increased food intake was sustained for 6 days, occurring in the light cycle of the first 2 days and subsequently switching to the dark cycle of the last 4 days. These time course profiles indicate the complexity of the mechanisms involved in AGRP-induced feeding.

Agouti-Related Protein↗
PubMed2001

A biochemical function for attractin in agouti-induced pigmentation and obesity.

Agouti protein, a paracrine signaling molecule normally limited to skin, is ectopically expressed in lethal yellow (A(y)) mice, and causes obesity by mimicking agouti-related protein (Agrp), found primarily in the hypothalamus. Mouse attractin (Atrn) is a widely expressed transmembrane protein whose loss of function in mahogany (Atrn(mg-3J)/ Atrn(mg-3J)) mutant mice blocks the pleiotropic effects of A(y). Here we demonstrate in transgenic, biochemical and genetic-interaction experiments that attractin is a low-affinity receptor for agouti protein, but not Agrp, in vitro and in vivo. Additional histopathologic abnormalities in Atrn(mg-3J)/Atrn(mg-3J) mice and cross-species genomic comparisons indicate that Atrn has multiple functions distinct from both a physiologic and an evolutionary perspective.

Agouti Signaling Protein↗
PubMed2001

[A study on steam generator in solid amine CO2 purification system].

Objective. To solve the key problems of power matching between process of CO2 steam desorption and process of steam generation, as well as water/vapor separation. Method. Solid amine desorption process was studied by thermodynamic analysis and experiments. The distribution rule of desorption energy was found out and then the power consumption of steam generator was decided. Ceramic insert was designed to separate water and vapor making use of surface tension. Finally, the steam generator was designed on system requirements. Result. Experiments proved that the steam generator can satisfy the demand of the system as well as successfully separate water and vapor, in addition, the selected power is suitable. Conclusion. The design on steam generator was right and practicable.

Air Conditioning↗
PubMed2001

Role of central melanocortin signaling in eating disorders.

Melanocortins are derived from posttranslational processing of the precursor protein pro-opiomelanocortin (POMC). The central melanocortinergic system consists of endogenous agonist alpha-melanocyte-stimulating hormone, the naturally occurring antagonist Agouti-related protein (AGRP), and two melanocortin receptors (MC3R, MC4R). Activation of central melanocortin receptors inhibits feeding and leads to weight loss, whereas blockade of the central melanocortin signaling pathway increases food consumption and promotes weight gain. This review will focus on the role of central melanocortin signaling in eating behavior and will evaluate studies of the neural pathways of POMC and AGRP systems, the effects of the central melanocortinergic system on food intake and body weight, and the regulation of hypothalamic POMC and AGRP neurons in response to altered feeding state and energy balance. In addition, this review will explore what is known about the interplay between the central melanocortinergic system and peripheral signals of energy homeostasis, i.e., leptin and glucocorticoids. Furthermore, evidence will be presented that genetic defects within the melanocortin signaling system are involved in determining susceptibility to obesity and anorexia in humans, and the therapeutic potential of melanocortin agonists and antagonists in the treatment of these disorders will be discussed.

Animals↗
PubMed2000

Differential distribution and regulation of OX1 and OX2 orexin/hypocretin receptor messenger RNA in the brain upon fasting.

To further understand the functions of the orexin/hypocretin system, we examined the expression and regulation of the orexin/hypocretin receptor (OX1R and OX2R) mRNA in the brain by using quantitative in situ hybridization. Expression of OX1R and OX2R mRNA exhibited distinct distribution patterns. Within the hypothalamus, expression for the OX1R mRNA was largely restricted in the ventromedial (VMH) and dorsomedial hypothalamic nuclei, while high levels of OX2R mRNA were contained in the paraventricular nucleus, VMH, and arcuate nucleus as well as in mammilary nuclei. In the amygdala, OX1R mRNA was expressed throughout the amygdaloid complex with robust labeling in the medial nucleus, while OX2R mRNA was only present in the posterior cortical nucleus of amygdala. High levels of OX2R mRNA were also observed in the ventral tegmental area. Moreover, both OX1R and OX2R mRNA were observed in the hippocampus, some thalamic nuclei, and subthalamic nuclei. Furthermore, we analyzed the effect of fasting on levels of OX1R and OX2R mRNA in the hypothalamic and amygdaloid subregions. After 20 h of fasting, levels of OX1R mRNA were significantly increased in the VMH and the medial division of amygdala. An initial decrease (14 h) and a subsequent increase (20 h) in OX1R mRNA levels after fasting were observed in the dorsomedial hypothalamic nucleus and lateral division of amygdala. Levels of OX2R mRNA were augmented in the arcuate nucleus, but remained unchanged in the dorsomedial hypothalamic nucleus, paraventricular hypothalamic nucleus, and amygdala following fasting. The time-dependent and region-specific regulatory patterns of OX1R and OX2R suggest that they may participate in distinct neural circuits under the condition of food deprivation.

Amygdala↗
PubMed2000

[The study on CO2 concentration in solid amine CO2 control system].

OBJECTIVE: To solve the problem of CO2 concentration and collection in solid amine CO2 control system for long-duration spacecraft cabin. METHOD: One approach was presented on the base of the principle of absorption and desorption, and was then tested by the apparatus according to it. RESULT: The average concentration of the concentrated CO2 was as high as 95%, which can be directly sent to the CO2 reduction system, and about 90% of the concentrated CO2 can be collected. CONCLUSION: The designed apparatus met the requirements of the CO2 reduction system.

Absorption↗
PubMed2000

[Design of reaction canister in a solid amine carbon dioxide removal system].

Objective. To design a reaction canister using in solid amine carbon dioxide removal system for long-duration spaceflight. Method. On consideration of system demand and properties of solid amine, key problems must be solved were found out: 1) the rated resistance limit tends to shorten the length of the canister while absorption and concentration require to increase the length of the canister; 2) limited quantity of heat for keeping the temperature of the canister; 3) inflation or contraction of the solid amine under micro-gravity. Result. After appropriate measures were taken, effective adsorption and desorption, as well as concentration of CO2 were achieved, the concentration of CO2 in the space cabin could be controlled below 0.5%; and the concentration of the concentrated CO2 was as high as 98% so that it could be directly send to the CO2 reduction system; and that the resistance of the canister was below 160 mm H2O; moreover, the energy consumption was decreased to below 650 W. Conclusion. The designed reaction canister could meet the requirements of the solid amine carbon dioxide (correction of bioxide) removal system under microgravity.

Adsorption↗
PubMed2000

[The development of a static water/gas separator].

Objective. To develop a device for separating water from gas in small flow rate under zero "G". Method. Beginning with the study of surface characteristic of materials, a capillary material was developed according to the requirement and the water/gas separator using this single separating material was designed. Result. The water/gas separator worked well in the range of gas flow below 10.0 L/min and water flow below 10.0 ml/min. No gas was found in the separated water and no water was found in the separated gas. Conclusion. The structure of the separator was reasonable and the water/gas separating method using a single separating material was feasible.

Air Conditioning↗
PubMed1999

Anatomy of an endogenous antagonist: relationship between Agouti-related protein and proopiomelanocortin in brain.

Agouti-related protein (AGRP) is a recently discovered orexigenic neuropeptide that inhibits the binding and action of alpha-melanocyte-stimulating hormone derived from proopiomelanocortin (POMC) at the melanocortin 3 receptor (MC3R) and melanocortin 4 receptor (MC4R) and has been proposed to function primarily as an endogenous melanocortin antagonist. To better understand the interplay between the AGRP and melanocortin signaling systems, we compared their nerve fiber distributions with each other by immunohistochemistry and their perikarya distribution with MC3R and MC4R by double in situ hybridization. Although deriving from distinct cell groups, AGRP and melanocortin terminals project to identical brain areas. Both AGRP and melanocortin neurons selectively express the MC3R, which provides a neuroanatomical basis for a dual-input circuit with biological amplification and feedback inhibition. These studies highlight a broader complexity in POMC-mediated behavior in the brain.

Agouti-Related Protein↗
PubMed1999

Regional distribution and cellular localization of gamma-aminobutyric acid subtype 1 receptor mRNA in the rat brain.

The distribution of gamma-aminobutyric acid (GABA) receptor subtype B1 (GABA(B1)) mRNA-containing cells in the brain of adult rats was determined with in situ hybridization histochemistry. The vast majority of neurons expressed GABA(B1) receptor mRNA. However, there were nuclei of relative high density, and, in some nuclei, the majority of neurons did not express detectable levels of GABA(B1) receptor transcripts. Areas where the majority of neurons expressed a high density of mRNA included the medial habenula; the septohippocampal, periventricular, suprachiasmatic, and supraoptic nuclei; Purkinje cells in the cerebellum; and pyramidal and granule cells of the hippocampus and dentate gyrus, respectively. Also, brainstem nuclei containing monoaminergic neurons and neurons in the thalamic motor nuclei contained relatively high levels of expression. mRNA was low or absent in neuronal populations in regions with well-developed cytoarchitecture, such as the stratum radiatum and stratum oriens of the hippocampus, the molecular and granular layers of the cerebellum, and the molecular layer of the cortex. Low expression was observed also in many extrapyramidal nuclei, such as the globus and ventral pallidum and the substantia nigra, pars reticulata. Expression also was low in the reticular thalamic nucleus and zona incerta. Neurons lacking detectable GABA(B1) receptor mRNA were generally in nuclei that contained largely GABAergic neurons.

Animals↗
PubMed1999

Expression of glutamate receptor subunit/subtype messenger RNAS for NMDAR1, GLuR1, GLuR2 and mGLuR5 by accumbal projection neurons.

Nucleus accumbens neurons are the targets of glutamatergic inputs. By coupling in situ hybridization for glutamate receptor mRNAs with retrograde transport of Fluoro-Gold, the present study examined the relationship between the distribution patterns of glutamate receptor subtypes/subunits and the output pathways of the nucleus accumbens to the ventral pallidum and ventral tegmental area. Following iontophoretic deposits of Fluoro-Gold into the ventral pallidum, neurons in both the nucleus accumbens shell and core were retrogradely labeled. A high percentage of accumbens neurons retrogradely labeled from the ventral pallidum were double-labeled for mRNAs encoding for mGluR5 (82+/-4.1%), NMDAR1 (71+/-3.5%), GluR1 (70+/-6.1%) and GluR2 (76+/-3.6%). No significant difference in the proportion of double-labeled neurons between the core and shell was observed. Following the deposit of Fluoro-Gold into the ventral tegmental area, only the accumbens shell neurons were retrogradely labeled. The proportion of neurons expressing NMDAR1, GluR1 and GluR2 were somewhat less in the projection to the ventral tegmental area compared to the ventral pallidum since approximately 60% of the neurons retrogradely-labeled from the ventral tegmental area expressed these transcripts. In contrast to the high proportion of mGluR5-containing neurons in the nucleus accumbens innervating the ventral pallidum, only half of the neurons projecting to the ventral tegmental area expressed mGluR5. These data show that accumbens neurons innervating the ventral pallidum and ventral tegmental area differ in the relative proportion of expressed mRNA encoding mGluR5, implying differential postsynaptic impact by glutamate transmission on neurons contributing to the two major efferent pathways of the nucleus accumbens.

Animals↗
PubMed1999

Neuroadaptations in ionotropic and metabotropic glutamate receptor mRNA produced by cocaine treatment.

The expression of glutamate receptor/subunit mRNAs was examined 3 weeks after discontinuing 1 week of daily injections of saline or cocaine. The level of mRNA for GluR1-4, NMDAR1, and mGluR5 receptors was measured with in situ hybridization and RT-PCR. In nucleus accumbens, acute cocaine treatment significantly reduced the mRNA level for GluR3, GluR4, and NMDAR1 subunits, whereas repeated cocaine reduced the level for GluR3 mRNA. Acute cocaine treatment also reduced the NMDAR1 mRNA level in dorsolateral striatum and ventral tegmental area. In prefrontal cortex, repeated cocaine treatment significantly increased the level of GluR2 mRNA. The GluR2 mRNA level was not changed by acute or repeated cocaine in any other brain regions examined. Repeated cocaine treatment also significantly increased mGluR5 mRNA levels in nucleus accumbens shell and dorsolateral striatum. Functional properties of the ionotropic glutamate receptors are determined by subunit composition. In addition, metabotropic glutamate receptors can modulate synaptic transmission and the response to stimulation of ionotropic receptors. Thus, the observed changes in levels of AMPA and NMDA receptor subunits and the mGluR5 metabotropic receptor may alter excitatory neurotransmission in the mesocorticolimbic dopamine system, which could play a significant role in the enduring biochemical and behavioral effects of cocaine.

Adaptation, Physiological↗
PubMed1999

[The inhibitory effect of amygdaloid stimulation on the "on-off" response of medial geniculate body neurons in rabbits].

Experiments were performed on 23 New Zealand rabbits immobilized with Flaxedil. The characteristics of on-off responses of medial geniculate body (MGB) neurons to tone bursts of varying frequency, intensity and duration were affected by lateral amygdaloid nucleus (LAm) stimulation, which was in form of altering the pattern of discharge or complete suppression. The effect also varied with the changes of the interval between amygdaloid stimulation and the tone bursts. The results of the present work show that LAm could modulate temporal processing of auditory information.

Acoustic Stimulation↗
PubMed1998

Expression of D1 receptor, D2 receptor, substance P and enkephalin messenger RNAs in the neurons projecting from the nucleus accumbens.

In situ hybridization was combined with FluoroGold retrograde labelling to determine the distribution of messenger RNAs for the D1 dopamine receptor, D2 dopamine receptor, beta-preprotachykinin or preproenkephalin in the neurons projecting from the nucleus accumbens to the ventral pallidum and the ventral tegmental area. Neurons were quantified in both the core and the shell of the nucleus accumbens to estimate the proportion of neurons projecting to the ventral pallidum or ventral tegmental area that contain transcripts for D1 receptors, D2 receptors, beta-preprotachykinin or preproenkephalin. Following the deposition of FluoroGold into the central ventral pallidum, both the core and the shell of the nucleus accumbens were retrogradely labelled, while deposits into the ventral tegmental area selectively labelled cells in the shell. A high percentage of nucleus accumbens neurons innervating the ventral tegmental area expressed messenger RNAs for D1 receptors (72%) and beta-preprotachykinin (62%), while less than 3% of the neurons contained messenger RNAs for preproenkephalin or D2 receptors. The neurons projecting to the ventral pallidum did not show the discrete distribution of transcripts as was observed in the accumbens-ventral tegmental area projection. Preproenkephalin messenger RNA was identified in 46% of the neurons innervating the ventral pallidum, and D2 receptor messenger RNA was found in approximately 40% of the cells. A large minority of neurons projecting from the nucleus accumbens to the ventral pallidum also expressed messenger RNAs for D1 receptors (37%) and beta-preprotachykinin (35%). While a higher percentage of D1 receptor, and beta-preprotachykinin messenger RNA expressing cells were located in the shell than in the core of the nucleus accumbens, the percentage tended to be higher in the core for cells expressing D2 receptors or preproenkephalin messenger RNA. These data indicate that messenger RNAs for D2 receptors and enkephalin are selectively expressed in the accumbens-pallidal projection while transcripts encoding D1 receptors and substance P are contained in the efferent projections to both the ventral pallidum and ventral tegmental area. The presence of D1 receptor and beta-preprotachykinin messenger RNAs in both mesencephalic and pallidal projections contrasts output from the striatum where the expression of D1 receptor and beta-preprotachykinin messenger RNAs is primarily restricted to the mesencephalic projection.

Animals↗
PubMed1997

Expression of D1 receptor mRNA in projections from the forebrain to the ventral tegmental area.

In situ hybridization was combined with Fluoro-Gold retrograde labeling to determine if cells projecting from the forebrain to the ventral tegmental area (VTA) express D1 receptor mRNA. Cell counts were made in the prefrontal cortex, shell of the nucleus accumbens, and ventral pallidum to estimate the percentage of neurons projecting to the VTA that express D1 receptor mRNA. Retrogradely labeled cells were observed in the infralimbic and prelimbic regions of the prefrontal cortex, and up to 37% of the retrogradely labeled cells expressed D1 receptor mRNA. Double-labeled cells constituted up to 89% of retrogradely labeled neurons in the rostral shell and up to 68% in the caudal shell of the nucleus accumbens. The number of retrogradely labeled cells in the ventral pallidum that were double-labeled ranged from 13% in the rostral to less than 10% in the caudal portions. These data provide anatomical support for a role of D1 receptors in the reciprocal innervation between the forebrain and VTA.

Animals↗