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Biomedical subjects

J Eng

Publications and source records attributed to J Eng.

At least 19 recordsLinked to original sources
PubMed2000

The role of CNS glucagon-like peptide-1 (7-36) amide receptors in mediating the visceral illness effects of lithium chloride.

Peripheral administration of large doses of lithium chloride (LiCl) to rats causes a spectrum of effects that are consistent with visceral illness. LiCl reduces food intake, decreases salt ingestion after sodium depletion, induces pica, and produces robust conditioned taste aversions. Because some of the effects of peripheral LiCl are mimicked by centrally administered glucagon-like peptide-1 (7-36) amide (GLP-1), we hypothesized that this peptide is involved in the neural pathways by which LiCl causes visceral illness. To test this hypothesis, we pretreated rats with a selective and potent GLP-1 receptor antagonist given directly into the third ventricle via an indwelling cannula before administration of peripheral LiCl. The GLP-1 receptor antagonist completely blocked the effect of LiCl to reduce food intake, induce pica, and produce a conditioned taste aversion. The same dose of GLP-1 receptor antagonist did not reverse the LiCl-induced reduction in NaCl intake. The data indicate a role for GLP-1 receptors in the CNS pathway that mediates some of the effects of visceral illness.

Angiotensins↗
PubMed2000

New structural model for Si/SiO2 interfaces derived from spherosiloxane clusters: implications for Si 2p photoemission spectroscopy

In this Letter, we investigate the Si/SiO(2) interface structure formed by the chemisorption of H8Si8O12 and other spherosiloxane clusters on Si(100). Using transition state calculations, we clearly demonstrate that the clusters do not bond to the Si(100) surface via single vertex attachment as proposed previously, but rather attach via Si-O bond cleavage. This alternative cracked cluster geometry allows us to predict the photoemission features of spherosiloxane clusters on Si(100) without invoking second nearest neighbor effects.

Journal Article↗
PubMed2000

Peripheral versus central effects of glucagon-like peptide-1 receptor agonists on satiety and body weight loss in Zucker obese rats.

The present study explores the potential utility of peripheral versus central administration of glucagon-like peptide-1 (GLP-1) receptor agonists in the regulation of feeding behavior in Wistar and Zucker obese rats. Acute central (intracerebroventricular [i.c.v.]) and peripheral (subcutaneous [s.c.]) administration of both GLP-1 (7-36) amide and exendin-4 resulted in a reduction in food intake for at least 4 hours, exendin-4 being much more potent than GLP-1 (7-36) amide, especially after peripheral administration. Both Zucker obese rats (fa/fa) and their lean littermates (Fa/-) responded to acute central and peripheral administration of exendin-4. Moreover, in situ hybridization revealed specific labeling for the mRNA for GLP-1 receptors in several brain areas of both the obese and lean rats. The presence of this receptor was also detected by affinity cross-linking assays. Long-term s.c. administration of exendin-4 (1 single injection per day, 1 hour prior to the onset of the dark phase of the cycle) decreased daily food intake and practically blocked weight gain in obese rats. In contrast to previous studies, these findings show that peripheral (s.c.) administration of both GLP-1 receptor agonists also induces satiety and weight loss in rats, and suggest the potential usefulness of exendin-4 as a therapeutic tool for the treatment of diabetes and/or obesity.

Amines↗
PubMed2000

Montgomery Thyroplasty Implant for vocal fold immobility: phonatory outcomes.

Forty-three patients with a diagnosis of unilateral vocal fold immobility underwent thyroplasty type I with the Montgomery Thyroplasty Implant System. Preoperative and postoperative evaluations were completed by means of videostroboscopic, acoustic, and aerodynamic measures. Clinicians' perceptions of vocal quality and patients' satisfaction with the surgery and vocal quality were determined. Improvements after surgery were observed for glottal closure, vocal fold amplitude, mucosal wave activity, average intensity, maximum intensity range, maximum phonation time, glottal airflow, average sound pressure, and subglottal pressure. Average postsurgical fundamental frequency values fell within normal limits and did not display significant changes relative to presurgical values. The clinicians' perceptual evaluations indicated an improvement in voice quality for most patients. A majority of patients expressed satisfaction with the surgery and resulting voice quality. The results of the present study, in combination with the surgical advantages that have been described for the Montgomery Thyroplasty Implant System, support the view that this approach offers an attractive alternative for treating unilateral vocal fold immobility.

Adolescent↗
PubMed2000

CT of primary cystic pancreatic neoplasms: can CT be used for patient triage and treatment?

OBJECTIVE: The purpose of this study was to determine whether CT can be used to distinguish serous cystadenomas from mucinous cystadenomas or cystadenocarcinomas of the pancreas and play an enhanced role in patient triage and treatment. MATERIALS AND METHODS: A blinded retrospective analysis of CT scans from 50 patients with pathologically proven primary cystic pancreatic neoplasms was performed independently by three radiologists. Using classic CT criteria as reported in the literature, each tumor was categorized as definitely serous, mucinous, or indeterminate. Tumor location, size, presence of calcification, and size of largest cyst were recorded. Data for each reviewer were analyzed independently. Consensus data were then subjected to multivariate logistic regression analysis. RESULTS: The ability of our reviewers to diagnose serous neoplasms ranged from 23% to 41%. Eight mucinous neoplasms were mistaken for serous tumors by two of the three reviewers. When consensus between at least two of the three reviewers was used for diagnosis, 27% of serous neoplasms were correctly diagnosed and all of the mucinous tumors were correctly identified as uncertain or mucinous, yielding the same clinical end point. For multivariate logistic regression analysis, a cyst smaller than 2 cm had a statistically significant association (p = 0.005) with serous tumors, and the presence of peripheral tumoral calcification had a statistically significant association (p = 0.01) with mucinous tumors. CONCLUSION: There is significant variability in the CT appearance of serous and mucinous neoplasms of the pancreas, making CT an insensitive tool for differentiating these tumors. All tumors with peripheral calcifications were identified as mucinous neoplasms.

Adult↗
PubMed2000

Interpretation of Emergency Department radiographs: a comparison of emergency medicine physicians with radiologists, residents with faculty, and film with digital display.

OBJECTIVE: We determined the relative value of teleradiology and radiology resident coverage of the emergency department by measuring and comparing the effects of physician specialty, training level, and image display method on accuracy of radiograph interpretation. MATERIALS AND METHODS: A sample of four faculty emergency medicine physicians, four emergency medicine residents, four faculty radiologists, and four radiology residents participated in our study. Each physician interpreted 120 radiographs, approximately half containing a clinically important index finding. Radiographs were interpreted using the original films and high-resolution digital monitors. Accuracy of radiograph interpretation was measured as the area under the physicians' receiver operating characteristic (ROC) curves. RESULTS: The area under the ROC curve was 0.15 (95% confidence interval [CI], 0.10-0.20) greater for radiologists than for emergency medicine physicians, 0.07 (95% CI, 0.02-0.12) greater for faculty than for residents, and 0.07 (95% CI, 0.02-0.12) greater for films than for video monitors. Using these results, we estimated that teleradiology coverage by faculty radiologists would add 0.09 (95% CI, 0.03-0.15) to the area under the ROC curve for radiograph interpretation by emergency medicine faculty alone, and radiology resident coverage would add 0.08 (95% CI, 0.02-0.14) to this area. CONCLUSION: We observed significant differences between the interpretation of radiographs on film and on digital monitors. However, we observed differences of equal or greater magnitude associated with the training level and physician specialty of each observer. In evaluating teleradiology services, observer characteristics must be considered in addition to the quality of image display.

Analysis of Variance↗
PubMed1999

Direct analysis of protein complexes using mass spectrometry.

We describe a rapid, sensitive process for comprehensively identifying proteins in macromolecular complexes that uses multidimensional liquid chromatography (LC) and tandem mass spectrometry (MS/MS) to separate and fragment peptides. The SEQUEST algorithm, relying upon translated genomic sequences, infers amino acid sequences from the fragment ions. The method was applied to the Saccharomyces cerevisiae ribosome leading to the identification of a novel protein component of the yeast and human 40S subunit. By offering the ability to identify >100 proteins in a single run, this process enables components in even the largest macromolecular complexes to be analyzed comprehensively.

Algorithms↗
PubMed1999

Neural contribution to the effect of glucagon-like peptide-1-(7-36) amide on arterial blood pressure in rats.

This study was designed to determine the contribution of the central nervous system (CNS) to the effects of glucagon-like peptide-1-(7-36) amide (tGLP-1) on arterial blood pressure and heart rate in rats. Accordingly, intracerebroventricular administration of the peptide produced an increase in cardiovascular parameters, which was blocked by previous administration of exendin-(9-39) through the same route, but not when it was intravenously injected. Intravenous administration of tGLP-1 produced a significant increase in arterial blood pressure and heart rate, which was blocked by the previous intracerebroventricular or intravenous administration of exendin-(9-39). Bilateral vagotomy blocked the stimulating effect of intracerebroventricular tGLP-1 administration on arterial blood pressure and heart rate. Also, bilateral vagotomy prevented the blocking effect of intracerebroventricular but not of intravenous exendin-(9-39) on cardiovascular parameters after intravenous administration of tGLP-1. These findings suggest that the action of tGLP-1 on cardiovascular parameters is under a dual control generated in the CNS and in peripheral structures and that the neural information emerging in the brain is transmitted to the periphery through the vagus nerve.

Animals↗
PubMed1999

CT angiography with volume rendering for quantifying vascular stenoses: in vitro validation of accuracy.

OBJECTIVE: The purpose of this study was to evaluate the accuracy of CT angiography with volume rendering for quantifying vascular stenoses in vitro. MATERIALS AND METHODS: Vascular models with three degrees of stenosis (33%, 67%, and 83%) were imaged at three orientations to the axial plane (parallel, perpendicular, or 45 degrees ) using helical CT with 2-mm collimation and two pitches (1 or 2), two reconstruction intervals (1 or 2 mm), and two scan times (.75 or 1 sec). Diameter and percentage of stenosis were measured from volume renderings using full width at half maximum. Images were measured in two planes whenever resolution varied with direction. Statistical analysis was performed using analysis of variance. RESULTS: Mean absolute error of the measured percentage of stenosis was 7% (range, 0-27%). The actual percentage of stenosis and vessel orientation had the most significant effects on accuracy (p < .001). The measured percentage of stenosis was significantly less accurate with phantoms parallel to the axial plane than with other orientations (p < .001). Mean absolute error in the measured percentage of stenosis was 4% when the parallel-to-the-axial-plane orientation was excluded. Overlapping (1-mm) reconstructions were significantly more accurate than 2-mm reconstructions (p < .05) and direction of measurement significantly affected accuracy (p < .05), but these effects were secondary. CONCLUSION: CT angiography with volume rendering can accurately quantify vascular stenoses, but it is less accurate for vessels in the axial plane. With 2-mm collimation, vessel characteristics have greater effects on accuracy than do acquisition parameters.

Analysis of Variance↗
PubMed1999

Neural networks for visual field analysis: how do they compare with other algorithms?

PURPOSE: To compare the performance of a neural network in identifying visual field defects with the performance of other available algorithms. METHODS: A feed-forward neural network with a single hidden layer was trained to recognize visual field defects previously collected in a longitudinal follow-up glaucoma study, and then tested on fields taken from the same study but not used in the training. The receiver operating characteristics of the network then were compared with the previously determined performance of other algorithms on the same data set. RESULTS: At a specificity greater than 90%, the neural network was more sensitive than any of the available algorithms (although only the global indices were available for comparison, as the cluster and cross-meridional algorithms did not achieve such high specificity at their current settings). At a lower specificity (80-85%), the neural network was unable to attain the high sensitivity of the cluster or cross-meridional algorithms; in fact, the cluster algorithm from the Low-Tension Glaucoma study was significantly more sensitive. CONCLUSION: The receiver operating characteristics of a feed-forward neural network designed to detect visual field defects were explored. At a very high specificity (90-95%) a neural network performed better than the global indices. However, at a lower specificity (78%-88%), the neural network performed worse than cluster and cross-meridional algorithms.

Algorithms↗
PubMed1999

Identification of clinical isolates of Mycobacterium spp. by sequence analysis of the 16S ribosomal RNA gene. Experience from a clinical laboratory.

Twenty-one mycobacterial type strains and 334 clinical isolates of mycobacteria were identified by standardized sequence analysis using part of the gene encoding 16S rRNA. Apart from two clinical isolates, the resulting sequences corresponded to previously published sequences. The results of the molecular determinations of the type strains completely overlapped the identities obtained using conventional techniques (cultural characteristics, biochemical tests, commercial DNA probes, and gas chromatographic lipid profiles). Of 323 isolates conventionally identified as slow-growing mycobacteria, 318 (98.5%) were identified to the same species or group level by 16S rDNA sequence analysis, while 6 of the 11 strains of rapid growers obtained a corresponding identity with the two approaches. The sequencing protocol combined with a few cultural characteristics (i.e. growth rate, pigmentation and susceptibility testing) offers a rapid, reliable and usually definite identification of mycobacterial isolates.

Amino Acid Sequence↗
PubMed1998

Central infusion of glucagon-like peptide-1-(7-36) amide (GLP-1) receptor antagonist attenuates lithium chloride-induced c-Fos induction in rat brainstem.

Central infusion of glucagon-like peptide-1-(7-36) amide (GLP-1) and intraperitoneal (i.p.) injection of lithium chloride (LiCl) produce similar patterns of c-Fos induction in the rat brain. These similarities led us to assess the hypothesis that neuronal activity caused by i.p. injection of LiCl involves activation of central GLP-1 pathways. We therefore determined if third-ventricular (i3vt) infusion of a GLP-1 receptor antagonist would block LiCl-induced c-Fos expression in the brainstem. Relative to rats pretreated with i3vt infusion of vehicle, pretreatment with the potent GLP-1 receptor antagonist, des His1 Glu9 exendin-4 (10.0 microgram), significantly attenuated LiCl-induced (76 mg/kg; i.p.) c-Fos expression in several brainstem regions, including the area postrema, the nucleus of the solitary tract, and the lateral parabrachial nucleus. While central infusion of des His1 Glu9 exendin-4 also blocked GLP-1-induced (10.0 microgram) anorexia and c-Fos expression, the antagonist produced no independent effects on food intake or c-Fos expression. These results suggest that LiCl-induced c-Fos expression in the rat brainstem is mediated, at least in part, by GLP-1 receptor signaling.

Animals↗
PubMed1998

Prevalence of Toxoplasma gondii specific immunoglobulin G antibodies among pregnant women in Norway.

During one year from June 1992 serum IgG antibodies to Toxoplasma gondii among 35,940 pregnant women were measured in a cross-sectional study conducted in Norway. The overall prevalence was 10.9%. The lowest prevalences were detected in the north (6.7%) and in the inland counties (8.2%). A significantly higher prevalence was detected in the southern counties (13.4%) where a mild, coastal climate prevails. Women with foreign names had a higher prevalence (22.6%) than women with Norwegian names (10.0%). The high prevalence among women living in the capital city (Oslo) as compared to other cities and rural areas (13.2% vs. 10.1% and 10.2% respectively), was explained by the higher proportion of foreign women in Oslo. Prevalence significantly increased with age in women over 34 years old. This increase was only detected among women with Norwegian names. An increase in prevalence according to number of children was detected. Women without children had a prevalence of 8.8% while women with three children or more had a prevalence of 14.9%. Multivariate analyses showed that being seropositive was independently associated with county of residence, age, nationality and number of children.

Adolescent↗
PubMed1998

Incidence of Toxoplasma gondii infection in 35,940 pregnant women in Norway and pregnancy outcome for infected women.

From 1992 to 1994 a screening program for detection of specific Toxoplasma gondii antibodies involving 35,940 pregnant women was conducted in Norway. For women with serological evidence of primary T. gondii infection, amniocentesis and antiparasitic treatment were offered. The amniotic fluid was examined for T. gondii by PCR and mouse inoculation to detect fetal infection. Infants of infected mothers had clinical and serological follow-up for at least 1 year to detect congenital infection. Of the women 10.9% were infected before the onset of pregnancy. Forty-seven women (0.17% among previously noninfected women) showed evidence of primary infection during pregnancy. The highest incidence was detected (i) among foreign women (0.60%), (ii) in the capital city of Oslo (0.46%), and (iii) in the first trimester (0.29%). Congenital infection was detected in 11 infants, giving a transmission rate of 23% overall, 13% in the first trimester, 29% in the second, and 50% in the third. During the 1-year follow-up period only one infant, born to an untreated mother, was found to be clinically affected (unilateral chorioretinitis and loss of vision). At the beginning of pregnancy 0.6% of the previously uninfected women were falsely identified as positive by the Platelia Toxo-IgM test, the percentage increasing to 1.3% at the end of pregnancy. Of the women infected prior to pregnancy 6.8% had persisting specific immunoglobulin M (IgM). A positive specific-IgM result had a low predictive value for identifying primary T. gondii infection.

Abortion, Spontaneous↗
PubMed1997

High potency antagonists of the pancreatic glucagon-like peptide-1 receptor.

GLP-1-(7-36)-amide and exendin-4-(1-39) are glucagon-like peptide-1 (GLP-1) receptor agonists, whereas exendin-(9-39) is the only known antagonist. To analyze the transition from agonist to antagonist and to identify the amino acid residues involved in ligand activation of the GLP-1 receptor, we used exendin analogs with successive N-terminal truncations. Chinese hamster ovary cells stably transfected with the rat GLP-1 receptor were assayed for changes in intracellular cAMP caused by the test peptides in the absence or presence of half-maximal stimulatory doses of GLP-1. N-terminal truncation of a single amino acid reduced the agonist activity of the exendin peptide, whereas N-terminal truncation of 3-7 amino acids produced antagonists that were 4-10-fold more potent than exendin-(9-39). N-terminal truncation of GLP-1 by 2 amino acids resulted in weak agonist activity, but an 8-amino acid N-terminal truncation inactivated the peptide. Binding studies performed using 125I-labeled GLP-1 confirmed that all bioactive peptides specifically displaced tracer with high potency. In a set of exendin/GLP-1 chimeric peptides, substitution of GLP-1 sequences into exendin-(3-39) produced loss of antagonist activity with conversion to a weak agonist. The results show that receptor binding and activation occur in separate domains of exendin, but they are more closely coupled in GLP-1.

Amino Acid Sequence↗
PubMed1997

Bilateral thoracotomy and inferior sternotomy for bypass grafting after esophagostomy.

In the presence of a cervical esophagostomy, a median sternotomy may jeopardize the stoma, risk mediastinal or sternal infection, and potentially compromise future esophageal operations. Coronary artery bypass grafting was performed using a modified bilateral thoracotomy before esophageal reconstruction in a patient with cervical esophagostomy. The surgical technique is described with a review of the relevant literature.

Aged↗