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Biomedical subjects

Y Liang

Publications and source records attributed to Y Liang.

At least 271 records · Page 15Linked to original sources
PubMed1997

Correlative studies of MR findings with neuropathology in Shy-Drager syndrome and striatonigral degeneration.

OBJECTIVE: To determine the pathologic bases of the abnormal signal intensities detected on magnetic resonance imaging (MRI) in Shy-Drager syndrome (SDS) and striatonigral degeneration (SND). METHODS: The correlation of MRI and pathological findings was prospectively evaluated by postmortem scanning of the brain in a case of SDS and another of SND. MRI was performed by using a 1.0 T superconductive magnetic unit, with spin echo (SE) pulse sequences. The brain sections were prepared parallel to the MRI planes. The gross and microscopic pathological studies were conducted according to the corresponding abnormal signal intensities on MRI. RESULTS: In SDS, abnormal hypointense signals on T2 weighted MR images were symmetrically demonstrated in bilateral putamen, where a remarkable positive Prussian blue stain reaction was revealed on pathological examinations. In SND, MRI showed isointense signals on T1 weighted images and hyperintense signals on T2 weighted images in bilateral putamen, and the microscopic findings included necrosis, abundant reactive fibrillary astrocytes and prominence of capillary vascular networks, as well as marked lipofuscin. The number of neurons decreased in both cases. CONCLUSIONS: The demonstration of the abnormal signals in the putamen on MRI is of important value in establishing an antemortem diagnosis of SDS and SND.

Female↗
PubMed1997

[Hypoglycemic effects of peroxovanadate complexes on glucose transportor of diabetic rats].

OBJECTIVE: To demonstrate the hypoglycemic effects and translocation of glucose transport (Glut 1 and Glut 4) promoted by peroxovanadate and nicotinic acid complexes (POR) in streptozotozin-induced diabetic rats. METHODS: Peroxovanadate complexes nicotinic acid (POR) was prepared in laboratory. POR and vanadate were administered in drink water. The muscles from diabetic rats were subjected to sucrose density gradient centrifugation to prepare plasma membrane and microsome membrane. Antibodies to COOH-terminal of glucose transportor were used in Western Blot to evaluate the translocation. RESULTS: Peroxovanadate complexes of nicotinic acid (POR) showed marked hypoglycemic effects on STZ-induced diabetic rats. 1mg/kg oral pathway POR could significantly reduce the plasma glucose levels (from 18.95 +/- 2.61mmol/L to 6.36 +/- 2.23mmol/L, t = 12.233, P < 0.01) over four week's treatment, whereas, same dose of single sodium vanadate or nicotinic acid did not have hypoglycemic effects. The net vanadium intake was about 1/90 of single effectively vanadate treatment. When Western blot was used POR increased the translocation of Glut 4 and Glut 1 from intracellular site of plasma membrane. CONCLUSION: Peroxovanadate-nicotinic acid complexes (POR) are the novel vanadyl that markedly reduce plasma glucose in a lower dose comparing to vanadate in STZ-DM rats by oral administration. Translocation of glucose transportor may play a part in hypoglycemic mechanism.

Animals↗
PubMed1997

Effects of peroxovanadate complexes on reducing glycemia in diabetic rats and translocation of glucose transporter.

OBJECTIVE: To demonstrate the hypoglycemic effects and translocation of glucose transporter (Glut 1 and Glut 4) promoted by peroxovanadate and nicotinic acid complexes (nicotinic chelated bitriperoxovanadate, POR; N-O nicotinic chelated peroxovanadate, POV) in streptozotozin-induced diabetic rats. METHODS: Peroxovanadate complexes of nicotinic acid (POR and POV) were prepared and characterized in laboratory. POR, POV and vanadate were administrated in drink water. The muscles from diabetic rats were subjected to prepare plasma membrane and microsome membrane. Antibodies to COOH-terminal of glucose transporter were used in Western Blot to evaluate the translocation. RESULTS: POR and POV showed markedly hypoglycemic effects in streptozotocin (STZ)-induced diabetic rats. POV, which may be a N-oxide compound of peroxovanadate, have high potency of acute effects comparing to carboxylate-complexes of peroxovanadate (POR). In chronic tests, 1 mg/kg oral pathway POR could significantly reduce the plasma glucose levels over four week's treatment, whereas the same dose of single sodium vanadate or nicotinic acid did not have hypoglycemic effects. The net vanadium intake is about 1/90 of single effectively vanadate treatment. The Western Blot showed that POR increased the translocation of Glut 4 and Glut 1 from intracellular site of membrane. CONCLUSIONS: Peroxovanadate-nicotinic acid complexes (POR and POV) are the novel vanadyl that acutely and markedly reduce plasma glucose in a lower dose comparing to vanadate in STZ-DM rats by oral administration. Translocation of glucose transportor may take a part in their hypoglycemic effects.

Animals↗
PubMed1997

[Application of otoadmittance to measure eustachian tube tympanometry].

This paper studied a simplified and quantified valsalva and reverse valsalva maneuver eustachian tube tympanometry with otoadmittance meter. In normal groups, the compliance changes were 0.57 +/- 0.23 ml with valsalva maneuver and 0.26 +/- 0.12 ml with reverse valsalva maneuver. Otherwise, the recordings were performed in various tympanic functions induced by various eustachian tube functions, and the results showed that this method was significant for the diagnosis of eustachian tube structure, obstruction or patency. The recording curves helped to determine the types and degrees of eustachian tube abnormality.

Acoustic Impedance Tests↗
PubMed1997

[A study on the transmission of plague though seven kinds of fleas in rat type and wild rodent type plague foci in Yunnan].

In order to assess vector position and vector action of seven kinds of fleas in the rat type and wild rodent type plague foci in Yunnan, we studied the indices as: infection rate, rate of feed bacterial emboli, colony transmission vector efficiency, life-span, bloodthirsty to human, body weight, quantity of blood-sucking, rate of dissociation by using animal model and raise film method. The results showed that Xenopsylla cheopis and Neopsylla specialis specialis were the main vectors of two type plague foci. Pulex irritans was an important vector of human plague in Yunnan. This paper reported that Xenopsylla cheopis and Neopsylla special special could twice form bacterial emboli, and with other information about vector efficiency, Index of Pulex irritans, Neopsylla special special, Frontopsylla spadix, Monopsyllus anisus, rate of bloodthirsty to human and life-span of seven kinds of fleas. Reason from quiescence to resuscitate was also deduced and the vector position of Leptopsylla segnis was revised. The vector action of main vector for Ctenophalmus quadratus was negated which proved that Apodemus chevrieri was the main reservoirs in these plague foci.

Animals↗
PubMed1997

[Role of substance P in pressor response of central amygdaloid nucleus to glutamate].

Substance P (SP)-immunoreactive cells and the axon terminals are widely distributed in the central amygdaloid nucleus (AC) and its important projection areas. The present study showed that (1) Excitation of the AC by glutamate (Glu) or injection of SP into the AC projection areas: locus coeruleus (LC), nucleus parabrachialis (NPB), periaqueductal gray matter (PAG) or lateral hypothalamus-perifornical region (LH/PF), all elicited pressor response. (2) Preinjection of DPDPDT (a SP antagonist) into bilateral LC, NPB, PAG or LH/PF could attenuate the AC pressor response to Glu. (3) Intra-RVLM (rostral ventrolateral medulla) preinjection of either phentolamine, propranolol or atropine (but not GDEE, a Glu antagonist) could also reduce the AC pressor response. Taken together with our previous findings that the alpha-, beta-, M-receptors in RVLM mediated the pressor response to LC excitation, alpha-receptors mediated the NPB pressor response, alpha- and beta-receptors mediated the PAG pressor response; these results indicate that the SPergic projections of the AC not only directly act upon the brainstem pressor areas (LC, NPB, PAG)-RVLM system, but also indirectly via the LH/PF act upon the brainstem pressor areas-RVLM system to induce the pressor response.

Amygdala↗
PubMed1997

[Experimental study on prevention and treatment of neuroma by implanting nerve stump into muscle].

Prevention and treatment of traumatic neuroma by implanting the proximal neural stump into the muscle were studied. Sixteen SD rats were used for the experimental study. The proximal stump of the left sciatic nerve was implanted into the nearby muscle as the experiment side, whereas the proximal stump of the right sciatic nerve was left untreated as the control side. The results were assessed with histological and electrophysiological methods. The experiment demonstrated that neuroma was formed in the control side one month postoperatively, whereas in the experimental side the nerve fibers were dispersed among the muscle fibers and no definite neuroma was formed. Implantation of neural stump into muscle could prevent and treat traumatic neuroma.

Animals↗
PubMed1996

Characterization of mutations in the beta subunit of the mitochondrial F1-ATPase that produce defects in enzyme catalysis and assembly.

The ATP2 gene, coding for the beta subunit of the mitochondrial F1-ATPase, was cloned from nine independent isolates of chemically mutagenized yeast. Seven different mutant alleles were identified. In one case the mutation occurs in the mitochondrial targeting sequence (M1I). The remaining six mutations map to the mature part of the beta subunit protein and alter amino acids that are conserved in the bovine heart mitochondrial and Escherichia coli beta subunit proteins. Biochemical analysis of the yeast atp2 mutants identified two different phenotypes. The G133D, P179L, and G227D mutations correlate with an assembly-defective phenotype that is characterized by the accumulation of the F1 alpha and beta subunits in large protein aggregates. Strains harboring the A192V, E222K, or R293K mutations assemble an F1 of normal size that is none-the-less catalytically inactive. The effect of the atp2 mutations was also analyzed in diploids formed by crossing the mutants to wild type yeast. Hybrid enzymes formed with beta subunits containing either the G133D, E222K, or R293K mutations are compromised for steady-state ATPase activity. The display of partial dominance confirms the importance of Gly133 for structural stability and of Glu222 and Arg293 for catalytic cooperativity.

Amino Acid Sequence↗
PubMed1996

Functional analysis of the SIS proximal element and its activating factors: regulated transcription of the c-SIS/PDGF-B gene in human erythroleukemia cells.

The SIS proximal element (SPE) is essential for the basal transcription of the c-sis/PDGF-B gene as well as the lineage-specific, activated transcription of this gene seen in megakaryocytes. In gel mobility shift analyses, the SPE element forms three gel-shift complexes; the t(op) and b(ottom) complexes were detected in nuclear extracts from both untreated and phorbol 12-myristate 13-acetate ('tetradecanoylphorbol acetate', TPA) treated K562 cells, whereas the m(iddle) complex was detected only in nuclear extracts from TPA-treated K562 cells. Site-directed mutagenesis of the SPE revealed a CCACCC motif that was essential for promoter activity as well as the formation of all three SPE gel-shift complexes. Nested-deletion analyses showed that the SPE was required for TPA-inducibility of c-sis/PDGF-B transcription. Antibody supershift analyses demonstrated that the t gel-shift complex contained both Sp1 and Sp3, and that the b complex contained only Sp3. In vitro transcription assays demonstrated that both Sp1 and Sp3 could support c-sis/PDGF-B transcription independent of each other in untreated K562 cells. However, overexpression of Sp1/Sp3 failed to significantly increase the c-sis/PDGF-B transcription in K562 cells.

Base Sequence↗
PubMed1996

Transcriptional regulation of the SIS/PDGF-B gene in human osteosarcoma cells by the Sp family of transcription factors.

Expression of PDGF-B, the gene encoding the platelet-derived growth factor B chain, has been implicated as a participant in an autocrine growth loop in the human osteosarcoma cell line U2-OS. In previous work, we identified a primary site in the PDGF-B promoter, the SIS proximal element (SPE), which is critical for transcription of the PDGF-B gene in U2-OS cells. We also identified Sp1 as one of the SPE-binding proteins in U2-OS nuclear extracts. In the present work, we have identified another SPE-binding protein to be Sp3. Gel mobility shift assays showed that both Sp1 and Sp3 require the CACCC motif within the SPE for binding. In vitro transcription assays showed that Sp1 or/and Sp3 is necessary for transcription of the PDGF-B gene. Cotransfection experiments functionally demonstrated that Sp1 and Sp3 can independently or additively activate the PDGF-B promoter through the SPE as well as a synthetic promoter. However, the CACCC motif within the SPE is not the only site within the minimal PDGF-B promoter through which Sp1/Sp3 acts; additional nested deletion analyses showed that multiple cis-acting elements within the minimal promoter are required for full level transcription of the PDGF-B gene in U2-OS cells.

Base Sequence↗
PubMed1996

World Wide Web interface to digital imaging and communication in medicine-capable image servers.

As a trial project, the Indiana University Department of Radiology has develop[ed a low-cost manner of distributing radiological images throughout a medical environment using the World Wide Web (WWW). The interface requires the user to have a WWW-browser client, such as Netscape, running on UNIX, PC, or Macintosh platforms. A forms-based interface allows the user to query several DICOM-capable machines at the machine, patient, study, series, and image levels. Once an image transfer is initiated, images are prewindowed from 16- to 8-bits, compressed using public domain Joint Photographic Expert Group (JPEG) compression routines, transferred to the WWW client program, and decompressed and displayed using a locally selected image viewing program. At the currently implemented level of compression (75% quality), the entire fetch-transform-JPEG-display process takes 2 to 5 seconds over Ethernet, depending on the platform used.

Computer Communication Networks↗
PubMed1996

Identification of an octamer-1 transcription factor binding site in the promoter of the mouse mu-opioid receptor gene.

In a previous study we showed that a region from -182 to +10 bp in the mouse mu-opioid receptor (MOR) promoter exhibited strong promoter activity. To identify protein-DNA interactions in this fragment, gel shift and DNase I footprint analyses were performed using nuclear extracts from mouse brain and the human neuroblastoma cell line, SK-N-SH. Two regions, nucleotide (nt) -121 to -100 and nt -42 to -22, were identified as being specific protein binding sites. The protein-DNA interaction in the nt -42 to -22 region was characterized in detail in this study. Methylation interference analysis of this region showed that nuclear protein from SK-N-SH cells contracted nucleotides within the sequence ATG-CAAAT, which is a binding motif for octamer trans-acting factors. An octamer-1 (Oct-1)-specific antibody super-shifted the protein-DNA complex in a gel shift assay. A UV cross-linking experiment showed that a nuclear protein, whose molecular weight is similar to that of the Oct-1 factor, bound to the octamer element in the nt -42 to -22 region. Mutagenesis of four base pairs within the octamer cis-acting element eliminated the specific protein binding in vitro. When the MOR-luciferase reporter construct (-182 to +10 bp) with the same four base pairs mutated was transiently transfected into SK-N-SH cells, a 200% increase in transcriptional activity was observed. Collectively, these data suggest that Oct-1 is binding to the octamer motif in the MOR gene and negatively modulating MOR gene expression.

Animals↗
PubMed1996

Alzheimer's disease associated with mutations in presenilin 2 is rare and variably penetrant.

Missense mutations in the presenilin 2 (PS-2) gene on chromosome 1 were sought by direct nucleotide sequence analysis of the open reading frame of 60 pedigrees with familial Alzheimer's disease (FAD). In the majority of these pedigrees, PS-1 and beta-amyloid precursor protein (beta APP) gene mutations had been excluded. While no additional PS-2 pathogenic mutations were detected, four silent nucleotide substitutions and alternative splicing of nucleotides 1338-1340 (Glu325) were observed. Analysis of additional members of a pedigree known to segregate a Met239Val mutation in PS-2 revealed that the age of onset of symptoms is highly variable (range 45-88 years). This variability is not attributable to differences in ApoE genotypes. These results suggest (i) that, in contrast to mutations in PS-1, mutations in PS-2 are a relatively rare cause of FAD; (ii) that other genetic or environmental factor modify the AD phenotype associated with PS-2 mutations; and (iii) that still other FAD susceptibility genes remain to be identified.

Age of Onset↗
PubMed1996

Phenotypic expression of Pseudomonas syringae avr genes in E. coli is linked to the activities of the hrp-encoded secretion system.

The specific recognition of elicitors produced by plant pathogenic bacteria carrying avirulence (avr) genes is postulated to initiate cellular defense responses in plants expressing corresponding resistance genes. The biochemical functions of most avr genes, however, are not known. A heterologous system was developed to phenotypically express Pseudomonas syringae avr genes in Escherichia coli cells that required the P. syringae hrp cluster. E. coli MC4100 transformants carrying the plasmic-borne P. syringae pv. syringae Pss61 hrp cluster and p. syringae pv. glycinea avrB expressed from a triple lacUV5 promoter gained the ability to elicit the hypersensitive response in soybean cultivars expressing Rpg1 and in an Arabidopsis thaliana accession expressing RPM1. Inactivation of energy transducing or outer membrane components of the hrp-encoded secretion system blocked phenotypic expression expression of avrB in E. coli, but deletions abolishing harpinPSS production had little effect on the production of the AvrB phenotype by the E. coli transformants. Phenotypic expression of avrA, AvrPto, avrRpm1, avrRpt2, and avrPph3 in E. coli was also shown to require the hrp cluster. The results indicate that generation of the Avr phenotype in P. syringae strains is specifically dependent on the secretion activities of the hrp cluster.

Base Sequence↗
PubMed1996

Dual-slice spiral versus single-slice spiral scanning: comparison of the physical performance of two computed tomography scanners.

In this paper we deal with two types of spiral scanners; one is a single-slice spiral scanner, while the other employs dual-slice technology into spiral scanning. Physical performance parameters, including image noise, contrast resolution, spatial resolution (transversal and longitudinal), and radiation exposure are measured. Computer simulations based on two interpolation methods (180 degrees and 360 degrees linear interpolation) are also used in evaluating the slice-sensitivity profile (SSP) and noise. The results show that the noise behaves in the same way for both types of scanners. The noise change, relative to that of the standard scan with the same scanning parameters, depends solely on the interpolation algorithm. Table speed and scanner geometry (either single slice or dual slice) have no effect on the noise value. For the given table speed, as well as individual detector collimation (slice width) the dual-slice scan results in better longitudinal resolution (SSP) compared to a single-slice scan if the scan is obtained with nonoverlapping slices (pitch greater than 2). This is because the dual-slice scan obtains twice the number of nonoverlapped projections for the same length, which reduces the degradation of the slice profile by using more densely arranged projections (in the longitudinal direction) for the interpolation. In the dual-slice scanner the workable scan rate is extended up to pitch 4 compared to a pitch of 2 for the single-slice scanner. Therefore, the dual-slice spiral scanner is preferred in applications requiring an increased scan rate with comparative image quality.

Computer Simulation↗