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Biomedical subjects

S Yang

Publications and source records attributed to S Yang.

At least 307 records · Page 17Linked to original sources
PubMed1998

The effect of morphine on responses of ventrolateral orbital cortex (VLO) neurons to colorectal distension in the rat.

In 49 halothane-anesthetized rats, we characterized the responses of single neurons in the ventrolateral orbital cortex (VLO) to a noxious visceral stimulus (colorectal balloon distension, CRD), and studied the effects of intravenous morphine on these responses using standard extracellular microelectrode recording techniques. One hundred and four neurons were isolated on the basis of spontaneous activity. Fifty-seven (55%) responded to CRD, of which 32% had excitatory and 68% had inhibitory responses. Neurons showed tendencies toward graded responses to graded CRD pressures (20-100 mmHg), with maximum excitation or inhibition occurring at 80 or 100 mmHg, respectively. Responses to noxious (pinch, heat) and innocuous (brush, tap) cutaneous stimuli were studied in 80 of the VLO neurons isolated. Thirty-three (41%) of these neurons (21 CRD-responsive and 12 CRD-nonresponsive) had cutaneous receptive fields, of which 79% were large and bilateral, 18% were small and bilateral, 3% were small and ipsilateral. Ninety-four percent of these neurons responded only to noxious cutaneous stimulation, 6% responded to both noxious and innocuous stimulation. No neurons responded solely to innocuous stimulation. Cumulative doses of morphine (0.0625, 0.125 and 0.25 mg/kg i.v.) produced statistically significant dose-dependent attenuation of neuronal responses to CRD. Naloxone (0.4 mg/kg i.v.) reversed the effects of morphine. Morphine and naloxone had no significant effects on spontaneous activity. These data support the involvement of VLO neurons in visceral nociception.

Animals↗
PubMed1998

Multistate surveillance for food-handling, preparation, and consumption behaviors associated with foodborne diseases: 1995 and 1996 BRFSS food-safety questions.

PROBLEM/CONDITION: In 1995, CDC, the Food and Drug Administration (FDA), and several state health departments collaboratively developed questions regarding food safety. This set of questions was used to collect data about food-handling, preparation, and consumption behaviors that have been associated with foodborne diseases in adults. These data will help characterize persons at high risk for foodborne illness and assist in developing food-safety education strategies for consumers and foodhandlers that are intended to reduce foodborne illness. REPORTING PERIOD COVERED: January 1995-December 1996. DESCRIPTION OF SYSTEM: Data were collected by using the 12 food-safety questions, which were administered with the 1995 Behavioral Risk Factor Surveillance Systems (BRFSS) in Colorado, Florida, Missouri, New York, and Tennessee, and the 1996 BRFSS in Indiana and New Jersey. In addition, data were collected in South Dakota from two of the standardized questions that deal with consumption of undercooked eggs and pink hamburgers. The BRFSS is a state-based system that surveys noninstitutionalized adults by telephone about their health behaviors and practices. RESULTS: This study included 19,356 completed questionnaires (2,461 in Colorado; 3,335 in Florida; 2,212 in Indiana; 1,572 in Missouri; 3,149 in New Jersey; 2,477 in New York; 2,110 in South Dakota; and 2,040 in Tennessee). During the previous 12 months, 50.2% of respondents reported eating undercooked eggs (95% confidence interval [CI] = 49.2-51.2); 23.8% reported eating home-canned vegetables (95% CI = 22.5-24.5); 19.7% reported eating pink hamburgers (95% CI = 18.9-20.5); 8.0% reported eating raw oysters (95% CI = 7.5-8.5); and 1.4% reported drinking raw milk (95% CI = 1.2-1.6). The prevalence of not washing hands with soap after handling raw meat or chicken and not washing a cutting board with soap or bleach after using it for cutting raw meat or chicken were 18.6% (95% CI = 17.8-19.4) and 19.5% (95% CI = 18.6-20.4), respectively. Less than half of respondents (45.4%, 95% CI = 44.2-46.6) reported seeing safe food-handling label information on raw meat products. In addition, among those persons who reported they remembered seeing the label information, 77.2% (95% CI = 76.0-78.4) remembered reading the label information, and 36.7% reported changing their meat and poultry preparation habits because of the labels (95% CI = 35.2-38.2). When population characteristics were considered in the analysis, all high-risk food-handling, preparation, and consumption behaviors were more prevalent in men than in women. Eating pink hamburgers during the previous 12 months was more commonly reported by whites (22.3%) than by blacks (6.5%). The prevalence of reported consumption of pink hamburgers during the previous. 12 months decreased with age (18-29 years: 21.8%, 30-59 years: 21.9%, and 60-99 years: 13.2%); increased with education (less than grade 12: 12.0%, high school graduate: 16.5%, and any college education: 24.0%); and increased with income (< $15,000: 11.8%, $15,000-$34,999: 17.6%, $35,000-$49,999: 22.0%, and > or = $50,000: 28.6%). INTERPRETATION: During 1995-1996, several high-risk food-handling, preparation, and consumption behaviors were common, and some were particular to specific population groups. Based on this analysis, interventions are needed to reduce the prevalence of these risky behaviors. All consumers and foodhandlers could benefit from food-safety education. ACTIONS TAKEN: Behavioral surveillance systems can provide data that identify persons or groups in which behaviors associated with foodborne diseases are more common and who are at higher risk for foodborne illness. State-specific data can assist in developing food-safety education programs and, if collected periodically, can be used to evaluate program effectiveness.

Adult↗
PubMed1998

Control of baculovirus polyhedrin gene expression by very late factor 1.

vlf-1 is a baculovirus gene that regulates very late gene expression (J. R. McLachlin and L. K. Miller, J. Virol., 68, 7746-7756, 1994) and also plays a crucial role in the replication of the budded form of Autographa californica nuclear polyhedrosis virus (AcMNPV) (S. Yang and L. K. Miller, "Expression and mutational analysis of the baculovirus very late factor 1 (vlf-1) gene." Virology, 245, 99-109, 1998). To examine the influence of vlf-1 expression on baculovirus infection, we constructed recombinant viruses that expressed only low levels of VLF-1 and recombinants with vlf-1 under the control of different promoters. Viruses with mutant alleles of vlf-1 that produced low levels of VLF-1 replicated the budded form of the virus normally but produced no occlusion bodies. Thus, a higher concentration of VLF-1 was needed to activate very late gene expression than was needed to support budded virus production. By altering the level and/or timing of vlf-1 expression, the timing of polyhedrin gene (polh) expression, which normally occurs very late in infection, could be advanced or delayed. Early overexpression of vlf-1 increased the level of expression from the polh promoter but caused premature cellular disintegration. The data indicate that VLF-1 is the limiting factor in very late gene expression and that the level of VLF-1 controls the onset of occlusion.

Animals↗
PubMed1998

Stress signaling through Ca2+/calmodulin-dependent protein phosphatase calcineurin mediates salt adaptation in plants.

Calcineurin (CaN) is a Ca2+- and calmodulin-dependent protein phosphatase (PP2B) that, in yeast, is an integral intermediate of a salt-stress signal transduction pathway that effects NaCl tolerance through the regulation of Na+ influx and efflux. A truncated form of the catalytic subunit and the regulatory subunit of yeast CaN were coexpressed in transgenic tobacco plants to reconstitute a constitutively activated phosphatase in vivo. Several different transgenic lines that expressed activated CaN also exhibited substantial NaCl tolerance, and this trait was linked to the genetic inheritance of the CaN transgenes. Enhanced capacity of plants expressing CaN to survive NaCl shock was similar when evaluation was conducted on seedlings in tissue culture raft vessels or plants in hydroponic culture that were transpiring actively. Root growth was less perturbed than shoot growth by NaCl in plants expressing CaN. Also, NaCl stress survival of control shoots was enhanced substantially when grafted onto roots of plants expressing CaN, further implicating a significant function of the phosphatase in the preservation of root integrity during salt shock. Together, these results indicate that in plants, like in yeast, a Ca2+- and calmodulin-dependent CaN signal pathway regulates determinants of salt tolerance required for stress adaptation. Furthermore, modulation of this pathway by expression of an activated regulatory intermediate substantially enhanced salt tolerance.

Adaptation, Physiological↗
PubMed1998

Adenosine mediates spinal norepinephrine-produced antinociception as revealed by nociceptive discharges in parafascicular neurons in rats.

The effects of intrathecal pretreatment with aminophylline on intrathecal norepinephrine-produced or serotonin-produced suppression of noxiously evoked discharges in thalamic parafascicular neurons were investigated in 35 urethane-anesthetized rats. The results showed that: (1) both intrathecal norepinephrine (15 nmol) or serotonin (20 nmol) produced significant suppression of noxiously evoked discharges in parafascicular neurons; (2) intrathecal aminophylline (120 nmol) blocked the norepinephrine-produced suppression of noxiously evoked discharges, while the same dose of aminophylline exhibited no significant effect on the serotonin-produced suppression of these discharges in parafascicular neurons. The results suggest that spinal norepinephrine-produced, but not serotonin-produced, antinociceptive effects may be mediated by adenosine as one of successive chemical links in the spinal dorsal horn circuitry.

Adenosine↗
PubMed1998

A baculovirus mutant defective in PKIP, a protein which interacts with a virus-encoded protein kinase.

We have found that a temperature-sensitive mutant of the baculovirus AcMNPV, tsB97, is defective in PKIP, the product of ORF24 which was previously found to interact with and stimulate the activity of a virus-encoded protein kinase, PK-1. The mutant lacks the ability to form plaques and occlusion bodies at the nonpermissive temperature. The mutant displays several properties which suggest a defect in the latter half of the late phase of infection; these properties include a delay in the shutoff of host protein synthesis, the presence of aberrant electron-dense bodies associated with the virogenic stroma, and the production of few, if any, progeny budded virus. A study of the expression of selected late genes showed no difference in the timing or level of transcription or translation of most late genes. However, elevated levels of the late 6.9K protein, a protamine-like protein, were observed in mutant-infected cells at 24 h postinfection, suggesting a defect in the regulation of this protein. Two polypeptides, 40 and 6 kDa, exhibited considerably higher levels of steady-state phosphorylation in wt-infected cells versus tsB97-infected cells at 24 h p.i. and could be candidates for PK-1/PKIP-mediated phosphorylation. The tsB97 mutant also displayed a severe defect in very late gene transcription which accounts for its inability to form occlusion bodies. The effect of PKIP on very late gene transcription may be a secondary effect of the block in the late phase of infection. PKIP showed no ability to transactivate expression from a very late promoter in transient expression assays.

Animals↗
PubMed1998

Overexpression of a novel Xenopus rel mRNA gene induces tumors in early embryos.

The Rel family of transcriptional activators form a large diverse group of proteins that are involved in the activation of genes involved in immunity, development, apoptosis and cancer. So far, none of the rel genes cloned in mammals appear to be required for embryonic development. We have cloned and characterized a cDNA from an embryonic cDNA library that encodes a novel Xenopus Rel protein, called Xrel3. Xrel3 is a member of the cRel subfamily and is most closely related to but distinct from other Xenopus Rel members. The expression of Xrel3 mRNA was investigated using Northern analysis, RNase protection assay, reverse transcriptase-linked polymerase chain reaction and in situ hybridization. Messages are present maternally and are slightly enriched in the equatorial region of the blastula stage embryo. At gastrulation, the accumulation of Xrel3 messages declines to undetectable levels but then increases after neurulation. In situ RNA hybridization was used to determine the spatial location of Xrel3 messenger RNA in embryos. Messages are localized to the developing forebrain, dorsal mid-hindbrain region, the inner ear primordium, or otocyst, and in the notochord. Overexpression by microinjection of Xrel3 RNA induced tumors in the developing embryo that appeared after gastrulation. The location of the tumors depended on the location of the injection site. These results suggest that Xrel3 might have a generalized role in regulation of cell differentiation in the embryo.

Amino Acid Sequence↗
PubMed1998

Expression and mutational analysis of the baculovirus very late factor 1 (vlf-1) gene.

We have examined the expression and function of a gene, vlf-1, of Autographa californica nuclear polyhedrosis virus that is known to encode a regulator of very late gene transcription. Western blot analysis revealed that vlf-1 is expressed during the late phase of infection, primarily from 15 to 24 h postinfection. VLF-1 localized in the cell nucleus and was also present in the nucleocapsids of virus particles. Mapping of vlf-1 mRNA by primer extension showed that transcription initiates at a TAAG motif 71 bp upstream of the vlf-1 open reading frame. Disruption of this TAAG motif abolished the ability of vlf-1 to stimulate transcription from the very late polyhedrin gene (polh) promoter in transient expression assays, suggesting that vlf-1 expression is controlled by the TAAG motif. Using a highly efficient system to construct recombinant viruses with modifications in vlf-1, we confirmed that the TAAG motif was essential. Furthermore, efforts to construct null mutants of vlf-1 failed, suggesting that vlf-1 is an essential gene for virus replication. Computer-assisted sequence homology searches place vlf-1 in the lambda phage integrase family (McLachlin and Miller, 1994). None of the strictly conserved residues of this family which are found in vlf-1 could be changed in the viral genome, implying that the putative integrase activity of VLF-1 is associated with the essential function of vlf-1. However, mutation of a crucial active-site tyrosine did not affect the ability of vlf-1 to transactivate the polh promoter in transient expression assays, indicating that the very late transcriptional activity of VLF-1 does not require the integrase activity.

Animals↗
PubMed1998

Expression of a knocked-in AML1-ETO leukemia gene inhibits the establishment of normal definitive hematopoiesis and directly generates dysplastic hematopoietic progenitors.

The t(8;21)-encoded AML1-ETO chimeric product is believed to be causally involved in up to 15% of acute myelogenous leukemias through an as yet unknown mechanism. To directly investigate the role of AML1-ETO in leukemogenesis, we used gene targeting to create an AML1-ETO "knock-in" allele that mimics the t(8;21). Unexpectedly, embryos heterozygous for AML1-ETO (AML1-ETO/+) died around E13.5 from a complete absence of normal fetal liver-derived definitive hematopoiesis and lethal hemorrhages. This phenotype was similar to that seen following homozygous disruption of either AML1 or CBFbeta. However, in contrast to AML1- or CBFbeta-deficient embryos, fetal livers from AML1-ETO/+ embryos contained dysplastic multilineage hematopoietic progenitors that had an abnormally high self-renewal capacity in vitro. To further document the role of AML1-ETO in these growth abnormalities, we used retroviral transduction to express AML1-ETO in murine adult bone marrow-derived hematopoietic progenitors. AML1-ETO-expressing cells were again found to have an increased self-renewal capacity and could be readily established into immortalized cell lines in vitro. Taken together, these studies suggest that AML1-ETO not only neutralizes the normal biologic activity of AML1 but also directly induces aberrant hematopoietic cell proliferation.

Animals↗
PubMed1998

Effect of melittin on PD, resistance and short-circuit current in the frog gastric mucosa.

In an in-vitro preparation of gastric mucosae of Rana pipiens, the effect of adding melittin to a concentration of 5x10-6 M in the secretory solution on the transepithelial potential difference (PD), resistance (R) and short-circuit current (Isc) was studied. In 20 min, melittin decreased the PD by 9.3 mV and R by 148 ohm cm2. These changes can be explained by a decrease in the resistance, RP, of the paracellular pathway. To determine whether specific-ion pathways were responsible for the decrease in R, the effect of melittin on the partial conductances of Cl-, K+ and Na+ was also studied using the ion substitution method. Melittin decreased the PD response to changes in nutrient Na+, K+ and Cl- and the PD response to changes in secretory Cl-, but did not affect PD responses to changes in secretory Na+ or K+. Therefore, melittin decreased the nutrient membrane partial conductances of Cl-, K+ and Na+ and secretory membrane partial conductance of Cl-, without affecting the secretory partial conductances of Na+ or K+. Initially, melittin increased Isc in regular and Cl--free but not in Na+-free solutions. There was a delayed decrease in Isc. The results indicate that melittin decreases RP, increases the Na+ conductance of the secretory membrane and inhibits, eventually, the Na+/K+-ATPase pump.

Animals↗
PubMed1998

Acute and chronic haemodynamic effects of naftazone in portal hypertensive rats.

It has been demonstrated that hyperproduction of nitric oxide (NO) plays a major role in the vasodilatation of cirrhosis; thus, the vasodilatation might be reversed by an inhibition of NO production. Experimental studies in isolated aortic rings showed that naftazone inhibits the effects of NO production. The aim of this study was to evaluate the haemodynamic effects of acute and chronic administration of naftazone in rats with portal hypertension. Haemodynamic values were measured either before and 10 min after intravenous administration of 432 microg/kg of naftazone or after 4 days of oral administration of 10 mg/kg per day. Acute administration of naftazone significantly reduced portal pressure in portal vein-stenosed and cirrhotic rats. This reduction was related to a decrease in the resistance of the liver and collateral circulation and it was associated with an increased cardiac output. Oral administration of naftazone significantly decreased portal pressure in rats with portal vein stenosis; this decrease depended on a significant reduction of portal blood flow. In both groups, arterial pressure did not change significantly. These haemodynamic effects differed from those observed following prazosin or propranolol administration. However, these effects were similar but less marked than those observed following N-nitro-L-arginine administration in systemic and splanchnic arterial territories. In conclusion, acute and oral administration of naftazone significantly reduces portal pressure by two different mechanisms in portal hypertensive rats. The exact mechanism has, however, to be elucidated.

Animals↗
PubMed1998

Identification and immunohistochemical localization of protein precursors to human axillary odors in apocrine glands and secretions.

OBJECTIVES: To determine the cellular localization in male and female axillary tissue for apocrine secretion odor-binding proteins 1 (ASOB1) and 2 (ASOB2) and the electrophoretic pattern of female apocrine proteins and to begin characterization of the ASOB1 protein. DESIGN: Immunohistochemical techniques were used with biopsy samples from axillary tissue of male and female subjects. Immunological techniques and microsequencing were used to characterize several of the proteins in male and female apocrine secretions. SETTING: A university medical center. PARTICIPANTS: Healthy male and female volunteers who donated apocrine secretions and/or axillary tissue. RESULTS: Specific immunoreactivity was localized only to the apocrine glands in both sexes. Furthermore, only preabsorption with a mixed apocrine secretion sample eliminated all immunoreactivity. The electrophoretic pattern of proteins in female apocrine secretions is similar to that in male secretions. Western blotting of the separated proteins from female samples using serum samples containing antibodies to ASOB1 and ASOB2 yielded identical results to those found with separated proteins from male samples. Partial sequence data obtained from the N-terminus of ASOB1 suggested that it shares homology with the alpha-chain of apolipoprotein J (Apo J). Apocrine secretion odor-binding protein 1 is not immunologically similar to ApoJ, but 2 other apocrine secretion proteins are. CONCLUSIONS: Male and female subjects appear to have the same glycoprotein carriers for (E)-3-methyl-2-hexenoic acid localized to the apocrine glands. The N-terminal sequence for ASOB1 may be homologous to Apo J, but it is not immunologically similar to it. However, 2 other proteins in the apocrine secretion appear to be the monomer and dimer forms of Apo J.

Adult↗
PubMed1998

Studies on the animal model of traumatic pseudoaneurysm.

Sixty-nine cases of pseudoaneurysm were made in 72 femoral arteries of 54 Japanese white rabbits, with a successful rate of 95.8%. Colored Doppler's ultrasonic imaging, CT, MRI, arterial angiography, anatomic dissection, and histologic observation were carried out at different times after the operation. The mechanism for the formation of pseudoaneurysm was discussed and the effects of colored Doppler's ultrasonic imaging, CT, MRI, and arterial angiography in the diagnosis of pseudoaneurysm were evaluated.

Aneurysm, False↗
PubMed1998

Wavelet-based vector quantization for high-fidelity compression and fast transmission of medical images.

Compression of medical images has always been viewed with skepticism, since the loss of information involved is thought to affect diagnostic information. However, recent research indicates that some wavelet-based compression techniques may not effectively reduce the image quality, even when subjected to compression ratios up to 30:1. The performance of a recently designed wavelet-based adaptive vector quantization is compared with a well-known wavelet-based scalar quantization technique to demonstrate the superiority of the former technique at compression ratios higher than 30:1. The use of higher compression with high fidelity of the reconstructed images allows fast transmission of images over the Internet for prompt inspection by radiologists at remote locations in an emergency situation, while higher quality images follow in a progressive manner if desired. Such fast and progressive transmission can also be used for downloading large data sets such as the Visible Human at a quality desired by the users for research or education. This new adaptive vector quantization uses a neural networks-based clustering technique for efficient quantization of the wavelet-decomposed subimages, yielding minimal distortion in the reconstructed images undergoing high compression. Results of compression up to 100:1 are shown for 24-bit color and 8-bit monochrome medical images.

Computing Methodologies↗
PubMed1998

Nicotinamide adenine dinucleotide phosphate oxidase in the formation of superoxide in osteoclasts.

Osteoclasts use a variety of chemical agents to degrade bone. One important component of this process is the generation of superoxide. It has been reported that nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is the enzyme responsible for superoxide production in phagocyte; however, the NADPH oxidase present in osteoclasts has not been studied in detail. One of the membrane-bound subunits of the NADPH oxidase is gp91(phox) which represents the rate-limiting component for the formation of the NADPH oxidase complex. This study was designed to demonstrate the presence of gp91(phox) in individual osteoclasts using the RT-PCR technique developed for limited numbers of cells. Compared with white cells, 1.8 times the amount of gp91(phox) mRNA was found in osteoclasts. This difference may be related to the size of the osteoclast and the multiple nuclei present. The presence of gp91(phox) in osteoclasts was confirmed at protein level by immunocytochemistry. Osteoclastic superoxide generation is inhibited by diphenylene iodonium, a specific inhibitor of the NADPH oxidase. These studies suggest that superoxide generation by osteoclasts correlates with the activity of NADPH oxidase.

Animals↗
PubMed1998

Different GABA-receptor types are involved in the 5-HT-induced antinociception at the spinal level: a behavioral study.

The effects of intrathecally (i.t.) administered GABA(A)-receptor antagonist picrotoxin or bicuculline on the antinociception produced by i.t. serotonin (5-HT), gamma-aminobutyric acid (GABA), muscimol--the GABA(A) agonist or baclofen--the GABA(B) agonist were investigated and compared using the tail-flick assay in rats. The results showed that 1) both i.t. picrotoxin (1.5 nmol) and i.t. bicuculline (0.5 nmol) exhibited a partial and later-emerged blockade on the antinociception produced by 5-HT (120 nmol) or GABA (1.5 nmol); 2) both i.t. picrotoxin and i.t. bicuculline, with the same dosages, completely blocked the antinociception produced by muscimol (1.0 nmol), but showed no effects on that produced by baclofen (0.3 nmol). The results suggest that GABA may mediate the 5-HT-induced antinociception at the spinal level, with the GABA(B)-receptors exhibiting the effect at the early-stage and the GABA(A)-receptors at the later stage of the 5-HT-induced antinociception.

Analgesics↗
PubMed1998

An efficient way to introduce unique restriction endonuclease sites into a baculovirus genome.

Recombinant baculoviruses which can be linearized at unique sites with restriction endonucleases can greatly facilitate the construction of other recombinants including baculovirus expression vectors and site-specific mutants. We designed a strategy to introduce unique restriction endonuclease sites at virtually any location in a baculovirus genome. The unique sites were first introduced onto a transfer plasmid which also contained in the vector portion of the plasmid an E. coli lacZ gene and a Sse8387I site, a sequence which is not found in the viral genome. Cotransfection of the transfer plasmid and circular viral DNA generated single-crossover recombinant viruses which could be distinguished as blue plaques in the presence of X-gal, a chromogenic indicator for lacZ. Single-crossover recombinants were purposefully isolated and propagated to generate double-crossover recombinants. Viral DNA isolated from the mixed virus population was digested with Sse8387I to linearize only the single-crossover viral DNA; double-crossover recombinants in the progeny viral population resulting from transfection with the Sse8387I-linearized viral DNA mixture were thus highly enriched, making the task of screening much easier. To demonstrate the feasibility of this approach, we introduced Bsu36I sites into the orf24 and the vlf-1 regions of Autographa californica multiple-nucleocapsid nuclear polyhedrosis virus (AcMNPV) to generate recombinant viruses vncBsuorf24 and vncBsuvlf1, respectively. Both recombinant viruses were obtained by screening only ten plaques. This method should also be applicable to other kinds of mutations and may be applicable to other double-stranded DNA viruses.

Animals↗