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Biomedical subjects

L Wang

Publications and source records attributed to L Wang.

At least 793 records · Page 44Linked to original sources
PubMed2000

Combined analyses of data from quantitative trait loci mapping studies. Chromosome 4 effects on porcine growth and fatness.

For many species several similar QTL mapping populations have been produced and analyzed independently. Joint analysis of such data could be used to increase power to detect QTL and evaluate population differences. In this study, data were collated on almost 3000 pigs from seven different F(2) crosses between Western commercial breeds and either the European wild boar or the Chinese Meishan breed. Genotypes were available for 31 markers on chromosome 4 (on average 8.3 markers per population). Data from three traits common to all populations (birth weight, mean backfat depth at slaughter or end of test, and growth rate from birth to slaughter or end of test) were analyzed for individual populations and jointly. A QTL influencing birth weight was detected in one individual population and in the combined data, with no significant interaction of the QTL effect with population. A QTL affecting backfat that had a significantly greater effect in wild boar than in Meishan crosses was detected. Some evidence for a QTL affecting growth rate was detected in all populations, with no significant differences between populations. This study is the largest F(2) QTL analysis achieved in a livestock species and demonstrates the potential of joint analysis.

Adipose Tissue↗
PubMed2000

The clinical utility of measuring total PSA, PSA density, gamma-seminoprotein and gamma-seminoprotein/total PSA in prostate cancer prediction.

BACKGROUND: To evaluate whether serum total prostate-specific antigen (PSA), PSA density (serum total PSA level divided by prostate volume), gamma-seminoprotein and gamma-seminoprotein/total PSA ratio could predict prostate cancer (PCa) prior to biopsy. METHODS: A total of 316 consecutive patients who had undergone transrectal prostate biopsy and/or transurethral resection were examined. The prostate volume was determined by transrectal ultrasonography (TRUS) and the ability of the above-mentioned four variables to distinguish PCa from benign prostatic hyperplasia (BPH) was evaluated. RESULTS: PCa was detected in 61 cases. Receiver-operating characteristic (ROC) analysis revealed that both the PSA density and serum total PSA were the most useful predictors of PCa among the four variables. For the patients with a serum total PSA level of 4.1-10.0 ng/ml, PSA density was significantly more accurate than total PSA (p < 0.005). An optimum PSA density value of 0.18 was chosen as a cutoff because it showed the highest sum of sensitivity and specificity, 92 and 54%, respectively. Using this PSA density cutoff, the number of biopsies could have been reduced to 57 from 63% when compared with a PSA density of 0.15. CONCLUSIONS: PSA density was significantly more accurate than other variables in predicting PCa. To avoid unnecessary biopsies, the PSA density cutoff value of 0.18 would be recommendable for determining a prostate biopsy for Japanese males with a serum total PSA level of 4.1-10.0 ng/ml.

Aged↗
PubMed2000

Expression and characterization of the human YWK-II gene, encoding a sperm membrane protein related to the alzheimer betaA4-amyloid precursorprotein.

The YWK-II cDNA, RSD-2, encoding a sperm membrane protein was isolated from a rat testis cDNA expression library. Using the RSD-2 insert in combination with rapid amplification of cDNA ends (RACE), the corresponding human gene was isolated from a human testis cDNA expression library. The human testis cDNA, HSD-2, is 3654 bp in length and contains an open reading frame of 763 codons. Hydropathicity analysis showed that the deduced polypeptide is a single strand transmembrane protein. The deduced polypeptide has partial homology with the amyloid precursor protein (APP) and high homology with the amyloid precursor homologue, APLP2/APPH. The YWK-II gene was mapped and assigned to human chromosome locus: 11q24-25. Northern blotting of various human tissue RNAs using the HSD-2 cDNA as a probe showed that the gene is transcribed ubiquitously. The cytoplasmic domain of HSD-2 was expressed in Escherichia coli. In-vitro studies showed that the recombinant polypeptide bound to a GTP-binding protein (G(o)) and was phosphorylated by protein kinase C and cdc2 kinase. In mammalian F11 cells, the recombinant polypeptide was found to be coupled to G(o). Thus, the YWK-II component has the characteristics of a G(o)-coupled receptor and may be involved in G(o)-mediated signal transduction pathway. Protein kinase C and cdc2 kinase may regulate this pathway in spermatozoa by phosphorylating the cytoplasmic domain of the YWK-II component.

Alzheimer Disease↗
PubMed2000

Involvement of progesterone in gonadotrophin-induced pituitary adenylate cyclase-activating polypeptide gene expression in pre-ovulatory follicles of rat ovary.

The present study was designed to determine whether progesterone might have a role in gonadotrophin-induced pituitary adenylate cyclase-activating polypeptide (Pacap) gene expression in rat ovary. Northern blot analysis revealed that treatment of pregnant mare's serum gonadotrophin (PMSG)-primed immature rats with the progestin antagonist RU486 or an inhibitor of 3beta-hydroxysteroid dehydrogenase epostane, 1 h before HCG, resulted in a dose-dependent inhibition of the HCG-induced Pacap gene expression. In-situ hybridization demonstrated that the number of pre-ovulatory follicles expressing Pacap mRNA in their granulosa cells was greatly reduced in ovaries treated with RU486. Moreover, the suppressive effect of RU486 or epostane on the LH-induced Pacap gene expression in cultured pre-ovulatory follicles was reversed by co-treatment with the synthetic progestin R5020. We further cloned the 5'-flanking region of the rat Pacap gene and identified the presence of a consensus progesterone receptor element. When luciferase fusion genes containing Pacap gene promoter were transiently transfected into granulosa cells of pre-ovulatory follicles, luciferase activity was markedly stimulated by LH. Treatment with RU486 or epostane resulted in partial suppression of LH-stimulated PACAP promoter activity. Taken together, these results indicate that progesterone, acting through progesterone receptors, plays a role in gonadotrophin induction of Pacap gene expression in granulosa cells of pre-ovulatory follicles, and thereby may be involved in the process of ovulation.

Androstenols↗
PubMed2000

LINE-1 (L1) lineages in the mouse.

Recently, a rapidly amplifying family of mouse LINE-1 (L1) has been identified and named T(F). The evolutionary context surrounding the derivation of the T(F) family was examined through phylogenetic analysis of sequences in the 3' portion of the repeat. The Mus musculus domesticus T(F) family was found to be the terminal subfamily of the previously identified L1Md4 lineage. The L1Md4 lineage joins the other prototypical mouse LINE-1 lineage (the L1MdA2 lineage) approximately 1 MYA at about the time of the common ancestor of M. m. domesticus, Mus spicilegus, and Mus spretus. However, the T(F) family from M. m. domesticus was found to join to the previously reported M. spretus Ms475 and Ms7024 LINE-1 families at just 0.5 MYA, indicating horizontal transfer. The T(F) family from M. m. domesticus was then found to be even more recently related to LINE-1's from another species, M. spicilegus. A separate spretus A2 lineage was found through a directed search of a PCR library. This lineage, in contrast to the spretus T(F) lineage, does join domesticus at about 1 MYA, as would be expected in the absence of horizontal transfer. A third major family was also found that splits off from the L1Md4 lineage shortly after its departure from the L1MdA2 lineage. The new family, named the Z family, was found to contain the de novo LINE-1 inserts causing the beige and med mutations. Whether the split with the Z family was before or after the recombination that introduced the F-type promoters and defined the inception of T(F) as a lineage is unclear. In enumerating copies of the various LINE-1 families, we found that T(F) 3' ends were not much more numerous than the reported number of 5' ends, suggesting that T(F) may not be subjected to the 90% truncation pattern typical of LINE-1 as a whole.

Animals↗
PubMed2000

Genetic structure of a 2,500-year-old human population in China and its spatiotemporal changes.

To examine temporal changes in population genetic structure, we compared the mitochondrial DNA (mtDNA) sequences of three populations that lived in the same location, Linzi, China, in different periods: 2,500 years ago (the Spring-Autumn era), 2,000 years ago (the Han era), and the present day. Two indices were used to compare the genetic differences: the frequency distributions of the radiating haplotype groups and the genetic distances among the populations. The results indicate that the genetic backgrounds of the three populations are distinct from each other. Inconsistent with the geographical distribution, the 2,500-year-old Linzi population showed greater genetic similarity to present-day European populations than to present-day east Asian populations. The 2, 000-year-old Linzi population had features that were intermediate between the present-day European/2,500-year-old Linzi populations and the present-day east Asian populations. These relationships suggest the occurrence of drastic spatiotemporal changes in the genetic structure of Chinese people during the past 2,500 years.

China↗
PubMed2000

Brain injury and cerebrovascular fibrin deposition correlate with reduced antithrombotic brain capillary functions in a hypertensive stroke model.

Hemostasis factors may influence the pathophysiology of stroke. The role of brain hemostasis in ischemic hypertensive brain injury is not known. We studied ischemic injury in spontaneously hypertensive rats in relation to cerebrovascular fibrin deposition and activity of different hemostasis factors in brain microcirculation. In spontaneously hypertensive rats subjected to transient middle cerebral artery occlusion versus normotensive Wistar-Kyoto (W-K) rats, infarct and edema volumes were increased by 6.1-fold (P < 0.001) and 5.8-fold (P < 0.001), respectively, the cerebral blood flow (CBF) reduced during middle cerebral artery occlusion (MCAO) by 55% (P < 0.01), motor neurologic score increased by 6.9-fold (P < 0.01), and cerebrovascular fibrin deposition increased by 6.8-fold (P < 0.01). Under basal conditions, brain capillary protein C activation and tissue plasminogen activator activity were reduced in spontaneously hypertensive rats compared with Wistar-Kyoto rats by 11.8-fold (P < 0.001) and 5.1-fold (P < 0.001), respectively, and the plasminogen activator inhibitor-1 antigen and tissue factor activity were increased by 154-fold (P < 0.00001) and 74% (P < 0.01), respectively. We suggest that hypertension reduces antithrombotic mechanisms in brain microcirculation, which may enhance cerebrovascular fibrin deposition and microvascular obstructions during transient focal cerebral ischemia, which results in greater neuronal injury.

Animals↗
PubMed2000

Intrastriatal transplantation of bone marrow nonhematopoietic cells improves functional recovery after stroke in adult mice.

The authors transplanted adult bone marrow nonhematopoietic cells into the striatum after embolic middle cerebral artery occlusion (MCAO). Mice (n = 23; C57BL/6J) were divided into four groups: (1) mice (n = 5) were subjected to MCAO and transplanted with bone marrow nonhematopoietic cells (prelabeled by bromodeoxyuridine, BrdU) into the ischemic striatum, (2) MCAO alone (n = 8), (3) MCAO with injection of phosphate buffered saline (n = 5), and (4) bone marrow nonhematopoietic cells injected into the normal striatum (n = 5). Mice were killed at 28 days after stroke. BrdU reactive cells survived and migrated a distance of approximately 2.2 mm from the grafting areas toward the ischemic areas. BrdU reactive cells expressed the neuronal specific protein NeuN in 1% of BrdU stained cells and the astrocytic specific protein glial fibrillary acidic protein (GFAP) in 8% of the BrdU stained cells. Functional recovery from a rotarod test (P < 0.05) and modified neurologic severity score tests (including motor, sensory, and reflex; P < 0.05) were significantly improved in the mice receiving bone marrow nonhematopoietic cells compared with MCAO alone. The current findings suggest that the intrastriatal transplanted bone marrow nonhematopoietic cells survived in the ischemic brain and improved functional recovery of adult mice even though infarct volumes did not change significantly. Bone marrow nonhematopoietic cells may provide a new avenue to promote recovery of injured brain.

Animals↗
PubMed2000

Gastric adenocarcinoma with a yolk sac component: a case report and review of the literature.

Gastric yolk sac tumors (YST) are very rare and are mainly reported in elderly people. We present a case of a 36-year-old man with a poorly differentiated gastric cancer showing a mixture of adenocarcinoma and yolk sac tumor that metastasized to Virchow's node. Both biopsies, Virchow's node and gastric tumor, contained areas of adenocarcinoma and yolk sac tumor that stained strongly positive for alpha fetoprotein (AFP) by the immunohistochemistry method. A high level of serum AFP (38,200 ng/mL) was also noted in this case. The response to chemotherapy in this case of mixed gastric yolk sac tumor and adenocarcinoma was not as favorable as would be expected in a pure primary germ cell tumor.

Adenocarcinoma↗
PubMed2000

Periodic oscillatory solution of bidirectional associative memory networks with delays.

Periodic oscillatory phenomena of bidirectional associative memory (BAM) networks with axonal signal transmission delays are investigated by constructing suitable Lyapunov functionals and some analysis techniques. Some simple sufficient conditions are derived ensuring the existence and uniqueness of periodic oscillatory solutions of the BAM with delays, and all other solutions of the BAM converge exponentially to a periodic oscillatory solution. These conditions are presented in terms of system parameters, and have an important leading significance in the design and applications of periodic oscillatory neural circuits for the BAM with delays.

Axons↗
PubMed2000

Adenosine kinase of Arabidopsis. Kinetic properties and gene expression.

To assess the functional significance of adenosine salvage in plants, the cDNAs and genes encoding two isoforms of adenosine kinase (ADK) were isolated from Arabidopsis. The ADK1- and ADK2-coding sequences are very similar, sharing 92% and 89% amino acid and nucleotide identity, respectively. Each cDNA was overexpressed in Escherichia coli, and the catalytic activity of each isoform was determined. Both ADKs had similar catalytic properties with a K(m) and V(max)/K(m) for adenosine of 0.3 to 0.5 microM and 5.4 to 22 L min(-1) mg(-1) protein, respectively. The K(m) and V(max)/K(m) for the cytokinin riboside N(6)(isopentenyl) adenosine are 3 to 5 microM and 0.021 to 0.14 L min(-1) mg(-1) protein, respectively, suggesting that adenosine is the preferred substrate for both ADK isoforms. In Arabidopsis plants, both ADK genes are expressed constitutively, with the highest steady-state mRNA levels being found in stem and root. ADK1 transcript levels were generally higher than those of ADK2. ADK enzyme activity reflected relative ADK protein levels seen in immunoblots for leaves, flowers, and stems but only poorly so for roots, siliques, and dry seeds. The catalytic properties, tissue accumulation, and expression levels of these ADKs suggest that they play a key metabolic role in the salvage synthesis of adenylates and methyl recycling in Arabidopsis. They may also contribute to cytokinin interconversion.

Adenosine↗
PubMed2000

QT dispersion from body surface ECG does not reflect the spatial dispersion of ventricular repolarization in sheep.

The correlation between the QT dispersion on body surface ECG and the dispersion in ventricular repolarization from the cardiac surface was studied in six sheep anesthetized with pentobarbital. The standard 12-lead body surface ECG and multiple ventricular epicardial ECGs were simultaneously recorded. The activation-recovery interval (ARI) was measured from the unipolar epicardial ECGs. The pooled QT dispersion from the six animals was significantly smaller than the pooled ARI dispersion (22.7 +/- 2.6 vs 33.0 +/- 6.9 ms, P < 0.01). There was no correlation between the QT and ARI dispersion. The unipolar epicardial ECGs were then converted into bipolar ECGs and epicardial QT intervals were subsequently acquired from these ECGs. The average value of epicardial QT dispersion from the six animals was similar to that of body surface ECG, but was less than the ARI dispersion (27.5 +/- 6.8 vs 33.0 +/- 6.9, P < 0.01). A good correlation between the epicardial QT dispersion and ARI dispersion was identified (r = 0.84, P < 0.05). In addition, a prolongation in ventricular repolarization, induced by an increase in coronary flow, elicited a pooled ARI dispersion of 62.3 +/- 6.2 ms (n = 6), which was larger than the simultaneously recorded body surface QT dispersion (28.3 +/- 9.8 ms, n = 6, P < 0.01). No correlation between the ARI and QT dispersion was found in the presence of the prolonged ventricular repolarization. In conclusion, QT dispersion from a 12-lead body surface ECG seems to underestimate the spatial dispersion of ventricular repolarization acquired from sheep epicardium.

Action Potentials↗
PubMed2000

Modeling tracer transport in an osteon under cyclic loading.

A mathematical model is developed to explain the fundamental conundrum as to how during cyclic mechanical loading there can be net solute (e.g., nutrient, tracer) transport in bone via the lacunar-canalicular porosity when there is no net fluid movement in the canaliculi over a loading cycle. Our hypothesis is that the fluid space in an osteocytic lacuna facilitates a nearly instantaneous mixing process of bone fluid that creates a difference in tracer concentration between the inward and outward canalicular flow and thus ensures net tracer transport to the osteocytes during cyclic loading, as has been shown experimentally. The sequential spread of the tracer from the osteonal canal to the lacunae is investigated for an osteon experiencing sinusoidal loading. The fluid pressure in the canaliculi is calculated using poroelasticity theory and the mixing process in the lacunae is then simulated computationally. The tracer concentration in lacunae extending radially from the osteonal canal to the cement line is calculated as a function of the loading frequency, loading magnitude, and number of loading cycles as well as the permeability of the lacunar-canalicular porosity. Our results show that net tracer transport to the lacunae does occur for cyclic loading. Tracer transport is found to increase with higher loading magnitude and higher permeability and to decrease with increasing loading frequency. This work will be helpful in designing experimental studies of tracer movement and bone fluid flow, which will enhance our understanding of bone metabolism as well as bone adaptation.

Animals↗
PubMed2000

Compatibility of Varian 2100C gated operations with enhanced dynamic wedge and IMRT dose delivery.

An enhanced dynamic wedge (EDW) is one of the latest technical innovations frequently used in the radiotherapy department. Its usage is enthusiastically supported by radiation therapists. Intensity modulated radiotherapy (IMRT) is the other, which has become popular within the past several years. Its usage is not as straightforward as the EDW. However, its ability to further increase dose conformity to the target and to spare the surrounding normal tissues has been evidenced. Both of these treatment modalities demand sophisticated software, which controls precision motion and speed of jaws or multileaf collimators as well as dose rate. This paper deals with the question of how accurately the EDW profiles and IMRT dose distributions be maintained when the additional constraint of linear accelerator gating is invoked. For this, square pulses mimicking breathing were used in gated and nongated modes for film dosimetry and ion chamber measurements using the Varian 2100C linear accelerator. The results show no observable difference between gated and nongated EDW profiles and IMRT dose distribution regardless of the machine repetition rate. Also studied in this paper are the "fuzzy" dose distributions caused by realistic finite gate window settings.

Humans↗
PubMed2000

Identification of distinct carboxyl-terminal domains mediating internalization and down-regulation of the hamster alpha(1B)- adrenergic receptor.

The roles of the carboxyl-terminal tail of the alpha(1B)-adrenergic receptor in its expression, function, and regulation were investigated by site-directed mutagenesis. The receptor construct truncated after residue 363 seemed not to be properly expressed. In contrast, the receptor truncated after residue 366 and all of the longer receptor constructs were properly expressed and exhibited agonist and antagonist binding and activation of phosphoinositide hydrolysis similar to the wild-type receptor. Agonist-induced sequestration of receptors within the plasma membrane, endocytosis into intracellular vesicles, and eventual down-regulation were all absent in the receptor truncated after residue 366. A series of sequential truncations and a deletion mutation identified a critical role for residues 403 to 425, which include the previously identified sites for G protein-coupled receptor kinase phosphorylation, in agonist-induced internalization of the receptor. Similar studies identified a critical role for residues 367 to 380 in agonist-induced down-regulation. Individual point mutations converting either cysteine 367 or serine 369 to alanine selectively eliminated down-regulation, thus identifying two specific amino acid residues required for down-regulation. Importantly, several of the mutated receptors that failed to show rapid agonist-induced internalization nonetheless exhibited normal agonist-induced down-regulation. In addition to identifying specific regions and individual residues of the alpha(1B)-adrenergic receptor involved in internalization and down-regulation, these studies provide mutated receptors that internalize but do not down-regulate, that down-regulate without internalization, and that are defective in both internalization and down-regulation, all of which should be useful tools for further studies of the specific cellular compartments and molecular mechanisms involved in receptor internalization and down-regulation.

Amino Acid Sequence↗
PubMed2000

Comparison of O-antigen gene clusters of Escherichia coli (Shigella) sonnei and Plesiomonas shigelloides O17: sonnei gained its current plasmid-borne O-antigen genes from P. shigelloides in a recent event.

Escherichia coli Sonnei has an O antigen identical to that of Plesiomonas shigelloides O17, and its O-antigen gene cluster is located on a plasmid. By sequencing the chromosomal O-antigen gene cluster of P. shigelloides O17 and comparing it with that of Sonnei, we showed that Sonnei gained its O-antigen genes recently.

Base Sequence↗
PubMed2000

The Escherichia coli O111 and Salmonella enterica O35 gene clusters: gene clusters encoding the same colitose-containing O antigen are highly conserved.

O antigen is part of the lipopolysaccharide present in the outer membrane of gram-negative bacteria. Escherichia coli and Salmonella enterica each have many forms of O antigen, but only three are common to the two species. It has been found that, in general, O-antigen genes are of low GC content. This deviation in GC content from that of typical S. enterica or E. coli genes (51%) is thought to indicate that the O-antigen DNA originated in species other than S. enterica or E. coli and was captured by lateral transfer. The O-antigen structure of Salmonella enterica O35 is identical to that of E. coli O111, commonly found in enteropathogenic E. coli strains. This O antigen, which has been shown to be a virulence factor in E. coli, contains colitose, a 3,6-dideoxyhexose found only rarely in the Enterobacteriaceae. Sequencing of the O35-antigen gene cluster of S. enterica serovar Adelaide revealed the same gene order and flanking genes as in E. coli O111. The divergence between corresponding genes of these two gene clusters at the nucleotide level ranges from 21.8 to 11.7%, within the normal range of divergence between S. enterica and E. coli. We conclude that the ancestor of E. coli and S. enterica had an O antigen identical to the O111 and O35 antigens, respectively, of these species and that the gene cluster encoding it has survived in both species.

Base Composition↗