Biomedical subjects

Y Shen

Publications and source records attributed to Y Shen.

At least 343 records · Page 19Linked to original sources

PubMed1997

Precision of the gallbladder ejection fraction obtained with Tc-99m-pyridoxyl-5-methyl-tryptophan (99mTc-PMT) hepatobiliary scintigraphy as compared with the contraction ratio in three-dimensional computed tomography.

UNLABELLED: The gallbladder ejection fraction (GBEF) obtained with Tc-99m-pyridoxyl-5-methyl-tryptophan (99mTc-PMT) hepatobiliary scintigraphy has been used as a parameter of gallbladder function. To determine the accuracy of GBEF, the relationship with the contraction ratio of the gallbladder (GBCR) obtained with three-dimensional helical computed tomography (3D-CT) was studied. PATIENTS AND METHODS: A normal volunteer, 8 patients suffering from cholecystolithiasis and a patient with gallbladder dyskinesia were examined. The percent initial dose (%ID) for the gallbladder and GBEF with hepatobiliary scintigraphy were used to compare the volume of the gallbladder and GBCR which was measured by 3D-CT. RESULTS: The %ID of the gallbladder was correlated with the volume of the gallbladder by 3D-CT (Y = 1.000X - 1.818, r = 0.928). GBEF was correlated well with GBCR by 3D-CT (Y = 0.916X + 6.296, r = 0.975). CONCLUSIONS: The %ID of the gallbladder obtained with hepatobiliary scintigraphy may be a good indicator of the volume of the gallbladder. The accuracy of GBEF was confirmed by comparison with 3D-CT examination. GBEF is considered a useful parameter of pathophysiological gallbladder function.

Adult↗

PubMed1997

Calcitonin provides complete protection against cancellous bone loss in the femoral neck of ovariectomized rats.

Calcitonin (CT) has been found to partially prevent cancellous bone loss in the proximal tibia of ovariectomized (OVX) rats. The current study was designed to determine whether CT has similar bone protective effects in the femoral neck, a skeletal site with a slower rate of bone loss after ovariectomy than the proximal tibia. Female Sprague Dawley rats were sham-operated or ovariectomized at 3 months of age. Groups of OVX rats were injected s.c. with vehicle or CT at a dose of 16 U/kg body weight on alternate days for 30, 60, or 90 days. Sham-operated control rats were treated with vehicle alone on alternate days. The proximal femur from each rat was processed undecalcified for quantitative bone histomorphometry. Cancellous bone volume in the femoral neck of vehicle-treated OVX rats was significantly less than that of vehicle-treated control rats at all time points. This cancellous osteopenia induced by ovariectomy was associated with increased indices of bone turnover such as osteoclast surface, osteoblast surface, and bone formation rate (tissue level, total surface referent). In contrast, cancellous bone volume in the femoral neck of CT-treated OVX rats was nearly identical of that of vehicle-treated control rats throughout the study. In addition, CT treatment of OVX rats decreased all indices of bone turnover to near the level of vehicle-treated control rats. The results indicate that CT treatment depresses bone turnover and provides complete protection against moderate cancellous osteopenia in the femoral neck of OVX rats. Since previous studies have shown that CT only partially protects against more pronounced cancellous bone loss in the proximal tibia of OVX rats, our findings suggest that CT has a greater bone protective effect at a skeletal site with a slower rate of cancellous bone loss (femoral neck) than at a skeletal site with a rapid rate of cancellous bone loss (proximal tibia).

Analysis of Variance↗

PubMed1997

Short- and long-term outcome of narrowed saphenous vein bypass graft: a comparison of Palmaz-Schatz stent, directional coronary atherectomy, and balloon angioplasty.

Percutaneous treatment of saphenous vein graft (SVG) stenosis has been established as an alternative to repeat coronary artery bypass grafting. Intracoronary Palmaz-Schatz stent (PSS) and directional coronary atherectomy (DCA) have been suggested to provide better short- and long-term results than balloon angioplasty. Records of 840 patients with 931 SVG lesions treated with PSS (121 patients, 132 lesions), DCA (103 patients, 107 lesions), and balloon angioplasty (616 patients, 692 lesions) were reviewed. Inhospital and long-term outcome were compared among treated groups. The groups had similar clinical and angiographic baseline characteristics except for higher previously dilated grafts in the stent group and graft location among devices. Stent placement was angiographically successful in 99%, DCA in 95%, and balloon angioplasty in 93% of the lesions (p = 0.03). Quantitative angiography revealed a larger lumen diameter after procedure after PSS (3.2 mm) and DCA (3.1 mm) compared with 2.4 mm after balloon angioplasty (p = 0.0001). Angiographic complications (abrupt closure, severe dissections, or distal embolization) were evident in eight (6.1%) lesions after PSS placement, in 17 (15.9%) after DCA, and in 61 (8.8%) after balloon angioplasty. Serious in-hospital clinical complications (death, emergency coronary artery bypass grafting, or Q-wave myocardial infarction) were similar among devices. Survival rates were similar among the groups (p = 0.15). Repeat revascularization at follow-up was reported in 58 (60.4%) of patients after PSS, in 48 (51.1%) after DCA, and in 280 (49.4%) after balloon angioplasty. Correlates of additional revascularization at follow-up were older grafts, calcific lesions, previously dilated grafts, longer lesions, and patients with lower ejection fractions (odds ratio 1.06, 1.34, 1.43, 1.04, and 1.01, respectively). Correlates of mortality rate at follow-up were older patients, patients with lower ejection fractions, and distal embolization (odds ratio 1.04, 1.04, and 1.92, respectively). These data suggest that in patents with SVG stenosis the initial success and morbidity rates are similar when comparing PSS and DCA with balloon angioplasty. Although a larger lumen is obtained with PSS and DCA, patients who underwent balloon angioplasty had similar rates of cardiac events and requirements for additional procedures at follow-up.

Aged↗

PubMed1997

Characterization of neuronal cell death induced by complement activation.

The complement system plays an important role in human immune defense mechanism. Its activation via either the classical or the alternative pathway can lead to the formation of membrane attack complex (MAC) and subsequently kills target cells. Activation of the classical pathway can be initiated with binding of C1q which is first factor of complement cascade to the Fc (fragment crystalline) region of immunoglobulin. This triggers a cascade of proteolytic events resulting in the activation of C5 convertase which cleaves C5 into C5b and C5a. The C5b then binds C6, C7, C8 to form a C5b-8 complex. Binding of C9 molecules to C5b-8 forms C5b-9, the MAC, which pore size increases as the number of C9 in the complex increases. If this membrane lesion persists and results in uncontrolled ion fluxes, the cells swell and eventually lyse. To restrict the activity of the complement system, endogenous complement inhibitors are available to regulate complement-mediated cytolysis. This enables the complement system to distinguish "self" from "foreign" and protect the host from inadvertent complement attack. Activation of the classical complement cascade has been reported in Alzheimer's disease and other neurodegenerative disorders. Recently, we demonstrated that complement activation causes neuronal cell death in vitro, and this neurodegenerative process is regulated by homologous restriction. In this article, we describe the use of two cell lines as in vitro models to evaluate cell injury/cell death induced by complement activation.

Animals↗

PubMed1997

Time course of femoral neck osteopenia in ovariectomized rats.

To characterize osteopenic changes in the femoral neck of ovariectomized (ovx) rats, female Sprague-Dawley rats were ovx or sham operated upon at 3 months of age and killed at various times from 0 to 360 days postsurgery. Quantitative bone histomorphometry was performed on undecalcified longitudinal sections of the proximal femur from each rat. This skeletal site was found to be slowly growing, as its rate of longitudinal bone growth in 3-month-old baseline control rats (5 microns/day) was nearly a factor of 10 less than that of a more commonly used sample site, the proximal tibia. In control rats, cancellous bone volume and cortical bone width of the femoral neck remained relatively constant, but cancellous mineral apposition rate declined with age during the course of the study. In contrast, cancellous bone volume in ovx rats was significantly decreased to 75%-82% of control level at 30-90 days and further decreased to 50%-56% of control level at later times postovariectomy. Indices of cancellous bone turnover such as osteoclast and osteoblast surfaces and bone formation rate were markedly increased in ovx rats at 30 days, declined toward control levels by 90 days, then increased moderately at 180-360 days. In comparison to control rats, a slight decrease in cortical width of the femoral neck was observed in ovx rats at 180 days and reached statistical significance at 360 days postovariectomy. Endocortical bone formation rate was increased significantly in ovx rats compared with control rats at most time points. The results indicate that both cancellous and cortical osteopenia associated with high bone turnover occur in the femoral neck of ovx rats. Cancellous bone loss at this skeletal site is statistically significant as early as 30 days postovariectomy, but remains relatively moderate for the first 90 days before becoming more pronounced at later times after ovariectomy. In contrast, cortical osteopenia was not observed in the femoral neck of ovx rats until 1 year postovariectomy. This histomorphometric characterization of osteopenic changes in the femoral neck of ovx rats may serve as a basis for use of this slowly growing sample site in preclinical studies of the prevention and treatment of bone loss in the estrogen-depleted skeleton.

Animals↗

PubMed1997

Large-scale sequencing in human chromosome 12p13: experimental and computational gene structure determination.

The detailed genomic organization of a gene-dense region at human chromosome 12p13, spanning 223 kb of contiguous sequence, was determined. This region is composed of 20 genes and several other expressed sequences. Experimental tools including RT-PCR and cDNA sequencing, combined with gene prediction programs, were utilized in the analysis of the sequence. Various computer software programs were employed for sequence similarity searches and functional predictions. The high number of genes with diverse functions and complex transcriptional patterns make this region ideal for addressing challenges of gene discovery and genomic characterization amenable to large-scale sequence analysis.

Alternative Splicing↗

PubMed1997

Sequencing and functional analysis of the SNRPN promoter: in vitro methylation abolishes promoter activity.

The gene encoding the small nuclear ribonucleoprotein-associated polypeptide N (SNRPN) maps to the Prader-Willi syndrome critical region on chromosome 15 and is expressed preferentially from the paternal allele. A CpG island encompassing the first exon of SNRPN is methylated on the inactive maternal allele. DNA sequence was determined for a cosmid containing the first three exons of SNRPN and extending 20 kb upstream and 15 kb downstream from the CpG island. This region is extremely rich in Alu elements and other repetitive sequences and contains a single CpG island, which includes numerous short direct repeat sequences. Functional analysis of the first exon revealed strong promoter activity for a 260-bp fragment extending 207 bp upstream from the exon. In vitro methylation of this 260-bp fragment abolished promoter activity completely, suggesting that the silencing of the maternal SNRPN allele may be a direct consequence of methylation of the promoter region.

Alleles↗

PubMed1997

Improvement of sensitivity of breast cancer diagnosis with adaptive neighborhood contrast enhancement of mammograms.

Mammograms are difficult to interpret, especially of cancers at their early stages. In this paper, we analyze the effectiveness of our adaptive neighborhood contrast enhancement (ANCE) technique in increasing the sensitivity of breast cancer diagnosis. Seventy-eight screen-film mammograms of 21 difficult cases (14 benign and seven malignant), 222 screen-film mammograms of 28 interval cancer patients and six benign control cases were digitized with a high-resolution of about 4096 x 2048 x 10-bit pixels and then processed with the ANCE method. Unprocessed and processed digitized mammograms as well as the original films were presented to six experienced radiologists for a receiver operating characteristic (ROC) evaluation for the difficult case set and to three reference radiologists for the interval cancer set. The results show that the radiologists' performance with the ANCE-processed images is the best among the three sets of images (original, digitized, and enhanced) in terms of area under the ROC curve and that diagnostic sensitivity is improved by the ANCE algorithm. All of the 19 interval cancer cases not detected with the original films of earlier mammographic examinations were diagnosed as malignant with the corresponding ANCE-processed versions, while only one of the six benign cases initially labeled correctly with the original mammograms was interpreted as malignant after enhancement. McNemar's tests of symmetry indicated that the diagnostic confidence for the interval cancer cases was improved by the ANCE procedure with a high level of statistical significance (p-values of 0.0001-0.005) and with no significant effect on the diagnosis of the benign control cases (p-values of 0.08-0.1). This study demonstrates the potential for improvement of diagnostic performance in early detection of breast cancer with digital image enhancement.

Breast Neoplasms↗

PubMed1997

Diabetic RBC-induced oxidant stress leads to transendothelial migration of monocyte-like HL-60 cells.

Red blood cells (RBC) from patients with diabetes mellitus exhibit an increased propensity to adhere to cultured human umbilical vein endothelial cells (HUVEC) as a result of interaction of advanced glycation end products with their counter receptors, contributing to the pathogenesis of vascular complications. We determined whether the interaction of diabetic RBC with HUVEC induced cellular oxidant stress that would culminate in adherence and diapedesis of monocytes, these being initiating events in endothelial injury and atherogenesis. We show that the adherence of diabetic RBC (2% hematocrit), but not normal RBC, to HUVEC results in a fourfold increase in the production of lipid peroxides. Furthermore, diabetic RBC-induced oxidant stress causes a sixfold increase in platelet endothelial cell adhesion molecule-1 (PECAM-1) phosphorylation and doubles transendothelial migration of monocyte-like HL-60 cells; both are blocked by antioxidants and protein kinase C (PKC) inhibitors. Our results show that the adherence of diabetic RBC to endothelial cells initiates a cascade of cellular events resulting in PKC activation, causing PECAM-1 phosphorylation and concomitant transendothelial migration of monocytes. The increased diapedesis of monocytes, brought about by the interaction of diabetic RBC across vascular endothelium, may play an important role in accelerated atherosclerosis and cardiovascular disease in diabetics.

Antioxidants↗

PubMed1997

Oxidant stress-induced transendothelial migration of monocytes is linked to phosphorylation of PECAM-1.

Reactive oxygen species (ROS) are believed to cause vascular injury in the pathophysiology of atherosclerosis, diabetes, and vasoocclusion in sickle cell disease. Studies have shown that ROS causes increased adhesion of monocytes and neutrophils to the endothelium. We investigated the effects of tert-butylhydroperoxide (t-BuOOH), an inducer of oxidant stress, to determine the cellular signaling pathway leading to the transendothelial migration of polymorphonuclear leukocytes. Our studies revealed that signaling by t-BuOOH in human umbilical vein endothelial cells (HUVECs) causes a twofold increase in the transendothelial migration of monocyte-like HL-60 cells and a fivefold increase in platelet endothelial cell adhesion molecule-1 (PECAM-1) phosphorylation. The transmigration induced by t-BuOOH was inhibited by an antibody to PECAM-1. These events were inhibited by antioxidants and inhibitors of protein kinase C, p21ras and glutathione synthesis. However, treatment of HUVECs with the phosphatase inhibitor calyculin A augmented the t-BuOOH-mediated transendothelial migration of monocytes and PECAM-1 phosphorylation. Our results suggest that oxidative stress can induce the transendothelial migration of monocytes as a result of phosphorylation of PECAM-1, a crucial event in the diapedesis of leukocytes during pathophysiology of vascular diseases.

Adenine↗

PubMed1997

Cadmium-induced oxidative cellular damage in human fetal lung fibroblasts (MRC-5 cells).

Epidemiological evidence suggests that cadmium (Cd) exposure causes pulmonary damage such as emphysema and lung cancer. However, relatively little is known about the mechanisms involved in Cd pulmonary toxicity. In the present study, the effects of Cd exposure on human fetal lung fibroblasts (MRC-5 cells) were evaluated by determination of lipid peroxidation, intra-cellular production of reactive oxygen species (ROS), and changes of mitochondrial membrane potential. A time- and dose-dependent increase of both lactate dehydrogenase leakage and malondialdehyde formation was observed in Cd-treated cells. A close correlation between these two events suggests that lipid peroxidation may be one of the main pathways causing its cytotoxicity. It was also noted that Cd-induced cell injury and lipid peroxidation were inhibited by catalase and superoxide dismutase, two antioxidant enzymes. By using the fluorescent probe 2',7'-dichlorofluorescin diacetate, a significant increase of ROS production in Cd-treated MRC-5 cells was detected. The inhibition of dichlorofluorescein fluorescence by catalase, not superoxide dismutase, suggests that hydrogen peroxide is the main ROS involved. Moreover, the significant dose-dependent changes of mitochondrial membrane potential in Cd-treated MRC-5 cells, demonstrated by increased fluorescence of rhodamine 123 examined using a laser-scanning confocal microscope, also indicate the involvement of mitochondrial damage in Cd cytotoxicity. These findings provide in vitro evidence that Cd causes oxidative cellular damage in human fetal lung fibroblasts, which may be closely associated with the pulmonary toxicity of Cd.

Cadmium↗

PubMed1997

The anatomy of the anterior origin of the deltoid.

We studied the origin of the anterior deltoid from the lateral third of the clavicle and the leading anterior edge of the acromion in 18 cadaver shoulders by anatomical and histological methods. The main origin of the deltoid was from the superior surface of the anterior acromion, but muscle and tendinous attachments were also seen on the entire anterior surface of the acromion, its anteroinferior surface and on the whole width of the anterior surface of the clavicle. Mock arthroscopic acromioplasty was shown to detach deltoid fibres from the anterior surfaces, leaving the superior attachment in continuity. Potentially, arthroscopic subacromial and clavicular resection can detach deltoid fibres originating from the anterior and anteroinferior surfaces of the acromion and clavicle and thus weaken the anterior deltoid.

Acromion↗

PubMed1997

Influence of dietary sulfur level on growth performance and digestive function in feedlot cattle.

Using ammonium sulfate, three levels of dietary S (.15, .20, and .25%, DM basis) were evaluated in a finishing trial with 108 yearling crossbred heifers (384 kg). The basal diet contained (DM basis) 4% alfalfa hay, 6% sudangrass hay, 74% steam-flaked corn, 4% yellow grease, 6% cane molasses, and 6% protein-mineral supplement. Increasing dietary S decreased ADG (quadratic effect, P < .10), DMI (linear effect, P < .10), feed efficiency (quadratic effect, P < .10), diet NE (quadratic effect, P < .10), and longissimus muscle area (linear effect, P < .05). Six Holstein steers (218 kg) with cannulas in the rumen and proximal duodenum were used to evaluate treatment effects on characteristics of digestion. Treatment effects on ruminal and total tract digestion of OM and N were small (P > .10). However, ruminal digestion of ADF and starch was slightly lower (quadratic effect, P < .10), and postruminal digestion of ADF and starch was correspondingly greater (quadratic effect, P < .05) with supplemental S. Dietary S level did not influence (P > .10) ruminal synthesis of microbial N. Increasing dietary S did not influence (P > .10) ruminal pH or lactic acid. Increasing S decreased molar proportions of acetate (quadratic effect, P < .10) and increased molar proportions of propionate (linear effect, P < .10). We conclude that S in excess of .20% of dietary DM may have detrimental effects on growth performance and dietary NE. Excessive dietary S may also compromise carcass merit by decreasing longissimus muscle area.

Animals↗

PubMed1997

Feeding value of cottonseed meal for feedlot cattle.

One hundred twenty crossbred steers (294 kg, initially) were used in a 141-d finishing trial. Four concentrations (8, 16, 24, and 32% of diet DM) of cottonseed meal (CSM, prepressed solvent-extracted) replaced steam-flaked corn in a corn-based finishing diet. Increasing level of CSM decreased ADG (linear component, P < .10), feed efficiency (linear component, P < .01), and dietary NE (linear component, P < .01). Observed dietary NE was 99% of expected at 8 and 16% CSM but 95% of expected at higher levels of inclusion (linear component, P < .05). Level of CSM did not influence (P > .10) dressing percentage, longissimus area, fat thickness, or retail yield. Eight Holstein steers (285 kg) were used in a replicated 4 x 4 Latin square design to evaluate treatment effects on characteristics of digestion. Ruminal digestibility of OM decreased (linear component, P < .05) as CSM increased, although ruminal digestibility of starch and feed N were not affected (P > .10). Ruminal escape protein from CSM was 58%. Total tract starch digestion was not altered (P > .10), but total tract digestibility of OM and GE decreased (linear component, P < .05) and digestion of N increased (linear component, P < .01) as CSM replaced steam-flaked corn. The ratio of observed to expected DE value of the diets was similar across CSM levels, averaging .99. Thus, comparative DE value of CSM was not affected by level of inclusion, averaging 3.32 Mcal/kg. We conclude that the NEm and NEg values of CSM are 1.88 and 1.24 Mcal/kg, respectively, and in close agreement with tabular values. However, CSM should not exceed 16% of DMI, because higher levels may depress cattle performance and replacement value of CSM.

Animals↗

PubMed1997

Simultaneous shotgun sequencing of multiple cDNA clones.

This study describes an efficient method for the rapid sequencing of DNA fragments in the size range 1-5 kb. Individual fragments, here cDNA inserts, are purified by restriction enzyme digestion and gel purification, pooled and concatenated by ligation. The concatamers are sheared and cloned randomly into M13, followed by random sequencing. The sequences of the individual cDNA inserts are obtained at the assembly stage using restriction enzyme sites as "tags' for the ends of each fragment. In this study the sequencing of two libraries containing 7 and 16 cDNA inserts with an average length of 2.5 kb is described. The results show that of the shotgun sequencing of large fragments, and that the method compares favorably to alternative strategies, such as primer walking.

Animals↗

PubMed1997

[An analysis on 30 cases of orbital schwannomas].

OBJECTIVE: To study isolated orbital schwannomas confirmed histopathologically in our hospital between 1985 and 1994. METHODS: The clinical features, diagnosis and treatment of 30 cases with the tumor were retrospectively studied. The postoperative complications and clinical recurrences after different surgical approaches were compared. RESULTS: Isolated orbital schwannoma occurs most commonly at the age of 20-40. The sex incidence is similar. Most of the patients complained of proptosis, some of them were accompanied by blurred vision, ocular pain, restricted ocular movement, etc. The tumors were resected surgically. In comparison with pre-operative visual acuity, the postoperative visual acuity was worse in 8 cases (26.7%), similar in 13 cases (43.3%), and improved in 9 cases (30.0%). There were early ptosis of the eyelid in 8 cases (26.7%) and restricted eye movement in 11 cases (36.7%). In 1.5-10 years of follow-up, clinical recurrences in 5 cases, one malignant and four benign, were seen. Most of the ptosis and restricted eye movement recovered after 3-6 months. CONCLUSION: According to the location of the tumor, the best surgical approach should be selected.

Adolescent↗

PubMed1997

[The effects of adrenergic antagonists on epinephrine determined by the assay of adenosine 3',5'-monophosphate in bovine trabecular cells in vitro].

OBJECTIVE: To compare and assay the effects of various beta-adrenergic antagonists at effective concentrations on epinephrine (EPI). METHOD: Cyclic adenosine 3',5'-monophosphate (cAMP) in trabecular cells was measured by protein binding assay with 3H-cAMP. RESULTS: (1) The effect of EPI increasing cAMP in bovine trabecular cells (BTC) in vitro did not obviously recover at the fifth hour after the removal of 10(-5) mol/L timolol, and partly recovered at the fifth hour after the removal of 10(-6) mol/L timolol. (2) There was only part recovery for the effect of EPI at the fifth hour after the removal of ICI 118, 551 (10(-5) mol/L, and 10(-6) mol/L). (3) There was an obvious recovery for the effect of EPI at the fifteenth minute after the removal of 10(-5) mol/L bisoprolol. CONCLUSION: The effect of timolol and ICI 118, 551 for blocking EPI is strong and sustained; bisoprolol produces a smaller blockade to the effect of EPI, lasting a short time. Our results also presume that BTC contains beta-adrenergic receptors, and beta 2-adrenergic receptors are dominant.

Adrenergic beta-Antagonists↗

PubMed1997

[beta-Endorphin enhances IL-2 and IFN-gamma gene expression in human blood mononuclear cells].

The effect of beta-endorphin (beta-END) stimulation of cytokines production by PHA-induced human peripheral blood mononuclear cells (PBMC) was studied by reverse transcription in combination with polymerase chain reaction (RT/PCR), slot blotting and hybridization to detect and measure messenger RNA (mRNA). beta-END significantly and dose dependently enhanced IFN-gamma and IL-2 mRNA expression of T cells and naloxone (Nal) reversed the effect of beta-END on IL-2 mRNA expression. The results further demonstrate the important link between the neural system and the immune system.

Dose-Response Relationship, Drug↗