Biomedical subjects

Y Li

Publications and source records attributed to Y Li.

At least 307 records · Page 17Linked to original sources

PubMed2003

Nitric oxide: a local signalling molecule controlling the activity of pre-autonomic neurones in the paraventricular nucleus of the hypothalamus.

AIM: The gas molecule nitric oxide (NO) has been shown to modulate autonomic function by acting both peripherally and centrally. Accumulating evidence indicates that the paraventricular nucleus (PVN) of the hypothalamus is an important locus mediating central NO actions on autonomic function, under both physiological and pathological conditions. However, the cellular targets and mechanisms mediating NO actions within the PVN are still poorly understood. RESULTS: By combining in vitro patch-clamp recordings with neuronal tract tracing techniques, we show that neuronal excitability of autonomic-related neurones in the PVN is tonically inhibited by an endogenous NO input. Furthermore, immunohistochemical studies show that approximately 25% of autonomic-related PVN neurones express neuronal nitric oxide synthase, suggesting that at least a proportion of them contribute to the cellular sources of NO within the PVN. CONCLUSION: In summary, this work suggests that NO modulation of the firing activity of autonomic-related PVN neurones constitutes an efficient mechanism mediated central NO regulation of autonomic function.

Action Potentials↗

PubMed2003

Reduction in excess sludge production by addition of chemical uncouplers in activated sludge batch cultures.

AIMS: To investigate the possibility of reducing excess sludge production in activated sludge processes by the addition of chemical uncouplers to greatly dissociate anabolism from catabolism. METHODS AND RESULTS: Ortho-chlorophenol (oCP), 2,4-dichlorophenol (DCP), 3,3',4',5-tetrachlorosalicylanilide (TCS), para-dinitrophenol (pNP) and 2,4-dinitrophenol (DNP) were chosen for short-term tests for their ability to reduce sludge yield by shaking bottle test. The most effective chemicals, DNP and pNP, together with TCS were tested for various uncoupler concentrations and biomass concentrations. TCS was tested in a lab-scale completely mixed activated sludge batch culture. The model (demonstrated by Liu) was verified with experimental data in completely mixed activated sludge batch test, but was inconsistent with the results from the shaking bottle batch test. The observed growth yield (Yobs) decreased with increasing of the ratio of initial uncoupler concentration to initial biomass concentration (Cu/X0). CONCLUSIONS: We suggest that the uncouplers oCP, DCP, TCS, pNP and DNP can cause a significant decrease in sludge production, the metabolism of which can explain the decline in sludge yield. SIGNIFICANCE AND IMPACT OF THE STUDY: The real strength of chemical uncoupler imposing on biomass should be Cu/X0, not initial uncoupler concentration (Cu) alone. Chemical uncouplers can be used to develop the activated sludge processes for minimizing excess sludge production.

Biomass↗

PubMed2003

TETRASPORE encodes a kinesin required for male meiotic cytokinesis in Arabidopsis.

A key step in pollen formation is the segregation of the products of male meiosis into a tetrad of microspores, each of which develops into a pollen grain. Separation of microspores does not occur in tetraspore (tes) mutants of Arabidopsis thaliana, owing to the failure of male meiotic cytokinesis. tes mutants thus generate large 'tetraspores' containing all the products of a single meiosis. Here, we report the positional cloning of the TES locus and details of the role played by the TES product in male cytokinesis. The predicted TES protein includes an N-terminal domain homologous to kinesin motors and a C-terminus with little similarity to other proteins except for a small number of plant kinesins. These include the Arabidopsis HINKEL protein and NACK1 and two from tobacco (Nishihama et al., 2002), which are involved in microtubule organization during mitotic cytokinesis. Immunocytochemistry shows that the characteristic radial arrays of microtubules associated with male meiotic cytokinesis fail to form in tes mutants. The TES protein therefore is likely to function as a microtubule-associated motor, playing a part either in the formation of the radial arrays that establish spore domains following meiosis, or in maintaining their stability.

Alleles↗

PubMed2003

Time-dependence of SI RA neuron response to cutaneous flutter stimulation.

Spike discharge activity of RA-type SI cortical neurons was recorded extracellularly in anesthetized monkeys and cats. Multiple applications (trials) of 10-50 Hz sinusoidal vertical skin displacement stimulation ("flutter") were delivered to the receptive field (RF). Analysis revealed large and systematic temporal trends not only in SI RA neuron responsivity (measured as spikes/s and as spikes/stimulus cycle), but also in entrainment, and in phase angle of the entrained responses. In contrast to SI RA neurons, the response of RA skin afferents to comparable conditions of skin flutter stimulation exhibited little or no dynamics. The occurrence and form of the SI RA neuron response dynamics that accompany skin flutter stimulation are shown to depend on factors such as stimulus frequency and the locus of the recording site in the global cortical response pattern. Comparison of recordings obtained in near-radial vs tangential microelectrode penetrations further reveals that the SI RA neuron response dynamics that occur during skin flutter stimulation are relatively consistent within, but heterogeneous across column-sized regions. The observed SI RA neuron response dynamics are suggested to account, in part, for the improved capacity to discriminate stimulus frequency after an exposure ("adaptation") to skin flutter stimulation (Goble and Hollins, J Acoust Soc Am 96: 771-780, 1994). Parallels with recent proposals about the contributions to visual perception of short-term primary sensory cortical neuron dynamics and synchrony in multineuron spike activity patterns are identified and discussed.

Anesthesia↗

PubMed2003

Role of abstinence and visual cues on food and smoking craving.

This study was designed to examine the relationship between cravings for food and cravings for cigarettes by presenting smoking-related or food-related visual cues to smokers who were either smoking-deprived or food-deprived. Fifteen regular cigarette smokers participated in this four-session, within-subject study in which they rated their craving for cigarettes and craving for food under four conditions: after abstaining from smoking, after abstaining from eating, after abstaining from both smoking and eating, or after no abstinence. We found that before presentation of the cues, overnight smoking abstinence increased craving for cigarettes, and overnight food abstinence increased craving for food. In each condition, presentation of cues further increased craving for the object of deprivation: smoking cues further increased craving for cigarettes after smoking abstinence, and food cues further increased craving for food after abstaining from food. Smoking abstinence did not affect craving for food, but food abstinence modestly increased smoking craving. These results indicate that craving for cigarettes or food is specifically increased by both deprivation from the substance and by presentation of substance-related cues.

Adolescent↗

PubMed2003

Vibrio neptunius sp. nov., Vibrio brasiliensis sp. nov. and Vibrio xuii sp. nov., isolated from the marine aquaculture environment (bivalves, fish, rotifers and shrimps).

The fluorescent amplified fragment length polymorphism (FAFLP) groups A5 (21 isolates), A8 (6 isolates) and A23 (3 isolates) distinguished in an earlier paper (Thompson et al., Syst Appl Microbiol 24, 520-538, 2001) were examined in more depth. These three groups were phylogenetically related to Vibrio tubiashii, but DNA-DNA hybridization experiments proved that the three AFLP groups are in fact novel species. Chemotaxonomic and phenotypic analyses further revealed several differences among the 30 isolates and known Vibrio species. It is proposed to accommodate these isolates in three novel species, namely Vibrio neptunius (type strain LMG 20536T; EMBL accession no. AJ316171; G +C content of the type strain 46.0 mol%), Vibrio brasiliensis (type strain LMG 20546T; EMBL accession no. AJ316172; G + C content of the type strain 45.9 mol%) and Vibrio xuii (type strain LMG 21346T; EMBL accession no. AJ316181; G +C content of the type strain 46.6 mol%). These species can be differentiated on the basis of phenotypic features, including fatty acid composition (particularly 14:0 iso, 14:0 iso 3-OH, 16:0 iso, 16:0, 17:0 and 17:1 omega8c), enzyme activities and utilization and fermentation of various carbon sources.

Animals↗

PubMed2003

Vibrio kanaloae sp. nov., Vibrio pomeroyi sp. nov. and Vibrio chagasii sp. nov., from sea water and marine animals.

The taxonomic position of the fluorescent amplified fragment length polymorphism fingerprinting groups A46 (five isolates), A51 (six isolates), A52 (five isolates) and A53 (seven isolates) obtained in a previous study were further analysed through a polyphasic approach. The 23 isolates were phylogenetically related to Vibrio splendidus, but DNA-DNA hybridization experiments proved that they belong to three novel species. Chemotaxonomic and phenotypic analyses further disclosed several features that differentiate between the 23 isolates and known Vibrio species. The names Vibrio kanaloae sp. nov. (type strain LMG 20539(T) = CAIM 485(T); EMBL accession no. AJ316193; G + C content 44.7 mol%), Vibrio pomeroyi sp. nov. (type strain LMG 20537(T) = CAIM 578(T); EMBL accession no. AJ491290; G +C content 44.1 mol%) and Vibrio chagasii sp. nov. (type strain LMG 21353(T) = CAIM 431(T); EMBL accession no. AJ316199; G + C content 44.6 mol%) are respectively proposed to encompass the five isolates of A46, the six isolates of A51 and the 12 isolates of A52/A53. The three novel species can be distinguished from known Vibrio species by several phenotypic features, including utilization and fermentation of various carbon sources, beta-galactosidase activity and fatty acid content (particularly of 12 : 0, 14: 0, 14 : 0 iso and 16 : 0 iso).

Animals↗

PubMed2003

Automatic verification of step-and-shoot IMRT field segments using portal imaging.

In step-and-shoot IMRT, many individual beam segments are delivered. These segments are generated by the IMRT treatment planning system and subsequently transmitted electronically through computer hardware and software modules before they are finally delivered. Hence, an independent system that monitors the actual field shape during treatment delivery is an added level of quality assurance in this complicated process. In this paper we describe the development and testing of such a system. The system verifies the field shape by comparing the radiation field detected by the built-in portal imaging system on the linac to the actual field shape planned on the treatment planning system. The comparison is based on a software algorithm that detects the leaf edge positions of the radiation field on the portal image and compares that to the calculated positions. The process is fully automated and requires minimal intervention of the radiation therapists. The system has been tested with actual clinical plan sequences and was able to alert the operator of incorrect settings in real time.

Quality Control↗

PubMed2003

Quantification of a multibeam sonar for fisheries assessment applications.

The acoustic theory is developed for a multibeam fisheries-type sonar employing a circular arc of transducer elements. Specifically, numerical relations for transmit and receive beam patterns are derived and methodologies set forth for the derivation of appropriately scaled acoustic target strength and acoustic volume backscattering strength from an ideally performing multibeam device. Predicted and measured beam characteristics of a realizable multibeam sonar, a Kongsberg Simrad-Mesotech SM 2000, are compared. Practical techniques for the extraction of calibrated acoustic volume backscattering strength from real systems are advanced.

Acoustics↗

PubMed2003

Organization and expression strategy of the ambisense genome of densonucleosis virus of Galleria mellonella.

The expression strategy of parvoviruses of the Densovirus genus has as yet not been reported. Clones were obtained from the densonucleosis virus of Galleria mellonella (GmDNV) that yielded infectious virus upon transfection into LD652 cells. Its genome was found to be the longest (6,039 nucleotides [nt]), with the largest inverted terminal repeats (ITRs) (550 nt) among all parvoviruses. The distal 136 nt could be folded into hairpins with flop or flip sequence orientations. In contrast to vertebrate parvoviruses, the gene cassettes for the nonstructural (NS) and structural (VP) proteins were found on the 5' halves of the opposite strands. The transcripts for both cassettes started 23 nt downstream of the ITRs. The TATA boxes, as well as all upstream promoter elements, were localized in the ITRs and, therefore, identical for the NS and VP transcripts. These transcripts overlapped for 60 nt at the 3' ends (antisense RNAs) at 50 m.u. The NS cassette consisted of three genes of which NS2 was contained completely within NS1 but from a different reading frame. Most of the NS transcripts were spliced to remove the upstream NS3, allowing leaky scanning translation of NS1 and NS2, similar to the genes of RNA-6 of influenza B virus. NS3 could be translated from the unspliced transcript. The VP transcript was not spliced and generated four VPs by a leaky scanning mechanism. The 5'-untranslated region of the VP transcript was only 5 nt long. Despite the transcription and translation strategies being radically different from those of vertebrate parvoviruses, the capsid was found to have phospholipase A(2) activity, a feature thus far unique for parvoviruses.

Amino Acid Sequence↗

PubMed2003

Oral vaccination of mice with adenoviral vectors is not impaired by preexisting immunity to the vaccine carrier.

Adenovirus vectors with E1 deleted of the human serotype 5 (AdHu5) and the chimpanzee serotype 68 (AdC68) expressing the glycoprotein of the Evelyn Rokiniki Abelseth strain of rabies virus were tested upon oral application for induction of systemic and mucosal transgene product-specific antibody responses in mice. Both vectors induced systemic and mucosal antibodies to rabies virus, including virus-neutralizing antibodies and protection against a severe intracerebral challenge with a mouse-adapted strain of rabies virus. Pre-existing immunity of AdHu5 virus, which dampens induction of transgene product-specific immunity elicited by AdHu5 vectors given systemically did not impair the response induced by oral vaccination. Oral priming-boosting regimens with either heterologous or homologous adenoviral vectors used sequentially increased both mucosal and systemic antibody titers to rabies virus [corrected]

Adenoviridae↗

PubMed2003

Human uveal melanoma expresses NG2 immunoreactivity.

BACKGROUND/AIMS: NG2 is the rat homologue of the human melanoma proteoglycan (HMP), also known as the high molecular weight melanoma associated antigen. Most cutaneous melanomas, as well as glioblastomas, chondrosarcomas, and some leukaemias express NG2 immunoreactivity, recognised using monoclonal antibody (mAb) 9.2.27. This antibody has also been used for molecular targeting in targeted alpha therapy for melanoma. The purpose of this study was to evaluate the expression of NG2 immunoreactivity in human uveal melanoma and normal ocular tissue using mAb 9.2.27. METHODS: Enucleated eyes from 26 patients with choroidal or ciliary body melanoma (n=26) were available as paraffin sections, and stained with haematoxylin and eosin to assess for tumour cell type and histopathology. Additional slides were investigated for NG2 immunoreactivity using mAb 9.2.27 and alkaline phosphatase anti-alkaline phosphatase (APAAP) immunostaining. Two independent observers graded immunostaining using a semiquantitative scale from 0 (negative) to 3 (strong). RESULTS: Immunostaining for mAb 9.2.27 could not be graded in 7/26 cases with dense pigmentation of the tumour. For the remaining cases, grade 2 (moderate) or more immunostaining was seen in 18/19 tumours (95%). The retina, retinal pigment epithelium (RPE), and choroid displayed weak immunostaining (grade 0.5-1.5) in the majority of melanoma affected eyes. Normal retina and choroid (n=5) appeared negative for mAb 9.2.27. Optic nerve axon bundles in both control and melanoma affected eyes displayed moderate immunostaining. CONCLUSION: In the present study, the majority of human uveal melanomas expressed NG2 immunoreactivity, as detected using mAb 9.2.27. This antibody may be a suitable candidate for radioimmunotherapy to target ocular melanoma.

Adult↗

PubMed2003

Effect of neonatal capsaicin treatment on haemodynamics and renal function in cirrhotic rats.

BACKGROUND: Mechanisms underlying abnormalities of circulation and renal function in cirrhosis are not completely understood. Our previous study revealed that primary afferent denervation by neonatal capsaicin treatment prevented the development of hyperdynamic circulation in portal hypertensive and cirrhotic rats. AIMS: The present study aimed to clarify the role of capsaicin sensitive nerves in the development of renal dysfunction and ascites formation in cirrhosis. METHODS: Rat pups were injected with capsaicin (50 mg/kg) or vehicle and allowed to grow. When they reached adulthood, cirrhosis was induced by bile duct ligation while controls received sham operation. Cardiac output and regional blood flows were measured by radioactive microspheres, glomerular filtration rate by (3)H inulin clearance, and urine volume, sodium excretion, and ascites formation were determined. Immunohistochemical staining for Fos in the brain stem cardiovascular regulatory nuclei, the nucleus of the solitary tract, and ventrolateral medulla was measured as an index of central neuronal activation. RESULTS: Increased cardiac output and renal blood flow, and decreased systemic vascular resistance, arterial pressure, renal vascular resistance, and glomerular filtration rate, as well as ascites, were found in vehicle treated cirrhotic rats. Neonatal capsaicin treatment completely blocked the development of hyperdynamic circulation and ascites, and improved renal function in cirrhotic rats. This was associated with complete abrogation of brain stem neuronal activation in capsaicin treated cirrhotic rats. CONCLUSIONS: These results indicate that intact primary afferent innervation is necessary for the development of not only the hyperdynamic circulation but also the renal dysfunction and ascites formation characteristic of cirrhosis.

Animals↗

PubMed2003

Protein transduction as a strategy for evaluating important factors in mammalian sex determination and differentiation.

Protein transduction is a powerful tool to deliver biologically active protein into mammalian cells and whole animals. Transduced proteins are folded properly and can mediate their respective functions in their hosts. To examine the feasibility of applying this strategy to study the molecular events of gonadogenesis, we have studied the kinetics of protein transduction and stability of transduced protein in in vitro mouse gonad culture systems using two reporter proteins, TAT-beta-gal and beta-gal fusion proteins with and without the TAT protein transduction domain (PTD) respectively. Our results indicate that the TAT-PTD was critical and essential for protein transduction to cultured fetal gonads. The TAT-beta-gal reporter entered the cells of the gonads and mesonephros efficiently for both sexes at E11.5 to E15.5 stages examined. The delivered protein persisted in the gonads for an extended period after an initial one-hour transduction. The distribution of the reporter was relatively even in gonads and mesonephros at E11.5 stage for both sexes and at later stages in female. The transduced protein was distributed heterogeneously in male gonads after seminiferous tubule differentiation in which the amount of reporter protein was higher outside than inside the tubules. Nevertheless, we surmise that such protein delivery technique should be useful in studies designed to evaluate the sex determining or differentiating functions of various new protein factors identified by advanced differential screening strategies.

Animals↗

PubMed2003

Characterization of two novel KRAB-domain-containing zinc finger genes, ZNF460 and ZNF461, on human chromosome 19q13.1-->q13.4.

This study reports the cloning and characterization of two novel human zinc finger protein cDNAs (ZNF460 and ZNF461) from a fetal brain cDNA library. The ZNF460 cDNA is 3,135 bp in length encoding a 562-amino-acid polypeptide and the ZNF461 cDNA is 2,548 bp encoding a 563-amino-acid protein. Both of the proteins contain a KRAB A+B box and eleven C2H2 type zinc finger motifs. ZNF461 shows high similarity with the rat GIOT-1 gene (GIOT1). The ZNF460 gene mapped to 19q13.4 with 3 exons, and ZNF461 mapped to 19q13.1 with 6 exons. Both of the two genes are ubiquitously expressed in normal human tissues and the abundance of the ZNF460 mRNA is relatively low.

Amino Acid Sequence↗

PubMed2003

Defective maturation of myeloid dendritic cell (DC) in NOD mice is controlled by IDD10/17/18.

We previously demonstrated that adoptive transfer of NOD pancreatic lymph node (PLN) DC protected recipients from diabetes. Our recent studies showed that the tolerogenic DC population presented islet antigens and were mature myeloid DC that did not produce IL-12, suggestive of exhausted or fully mature DC. Extensive characterization of the DC population in vivo in NOD and control mice demonstrated a specific deficiency of PLN tolerogenic DC in older mice. These findings suggest autoimmunity might arise in NOD mice secondary to deficient maturation of myeloid DC to a tolerogenic state. To address this issue, we characterized maturation and function at development of bone marrow-derived myeloid DC from NOD and several control strains. We found that NOD DC were highly resistant to several maturation stimuli and maintained an immature phenotype (average % immature DC: 75% in NOD versus 15% in B6, p < 0.01). A survey of congenic NOD mice with various NOD diabetes susceptibility loci demonstrated that the IDD10/17/18 region on chromosome 3 controlled approximately 50% of the NOD DC maturation defect. The defect also affected NOD DC that underwent phenotypic maturation. These cells appeared to arrest in a "maturing" phase as they produced 5- to 7-fold more IL-12 than control strains and significantly less IL-10. The cytokine defect was completely corrected in NOD IDD10/17/18 mice. In addition, the IDD10/17/18 locus limited DC accumulation in islets and significantly increased tolerogenic DC in the PLN. Together, the above findings suggest that polygenic regulation of DC maturation defects in NOD mice promotes islet inflammation while limiting the generation of tolerogenic DC.

Animals↗

PubMed2003

Abnormal peripheral blood dendritic cell populations in type 1 diabetes.

Type 1 diabetes (T1D) is a T cell-mediated disease. Various DC populations play important roles in initiating and directing T cell responses and thus may be critical for T1D pathogenesis. We thus examined peripheral blood DC1 and DC2 populations by flow cytometry in healthy controls, subjects at risk for T1D, new-onset patients, and established T1D patients. We found a significant increase in the number of DCs (including DC1 and DC2) in at-risk subjects and those with new-onset T1D versus healthy controls and established T1D patients (ANOVA; p < 0.0001). Analysis of DC1 and DC2 subsets in these same groups demonstrated a significant decrease in the ratio of DC1 and DC2 in subjects at risk and new-onset and established T1D patients in contrast with healthy controls (p < 0.0001). Both subsets of peripheral blood DCs from T1D patients expressed significantly higher levels of HLA-DR than healthy controls. Peripheral blood mononuclear cells from T1D patients secreted significantly higher amounts of IFN-alpha than controls, and IFN-alpha production correlated inversely with the DC1/DC2 ratio. This study demonstrates a marked increase in peripheral blood DC numbers that occurs during a time of active autoimmunity in at-risk subjects and patients with new-onset T1D, but is lost in established diabetes. However, the abnormal distribution of peripheral blood DC populations appears to be a persistent phenotype in all stages of T1D.

Case-Control Studies↗

PubMed2003

Expression differences in mitochondrial and secretory chaperonin 60 (Cpn60) in pancreatic acinar cells.

In pancreatic acinar cells, chaperonin Cpn60 is present in all the cellular compartments involved in protein secretion as well as in mitochondria. To better understand the role Cpn60 plays in pancreatic secretion, we have evaluated its changes under experimental conditions known to alter pancreatic secretion. Quantitative protein A-gold immunocytochemistry was used to reveal Cpn60 in pancreatic acinar cells. Cpn60 immunolabelings in cellular compartments involved in secretion were found to decrease in acute pancreatitis as well as upon stimulation of secretion and in starvation conditions. A major increase in Cpn60 was recorded in diabetic condition. This was normalized by insulin treatment. Although in certain situations changes in secretory enzymes and in Cpn60 correlate well, in others, nonparallel secretion seemed to take place. In contrast, expression of mitochondrial Cpn60 in acinar cells appeared to remain stable in all conditions except starvation, where its levels decreased. Expression of Cpn60 in the secretory pathway and in mitochondria thus appears to behave differently, and Cpn60 in the secretory pathway must be important for quality control and integrity of secretion.

Animals↗