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Biomedical subjects

J Yee

Publications and source records attributed to J Yee.

At least 91 records · Page 5Linked to original sources
PubMed1994

Acute appendicitis: CT and US correlation in 100 patients.

PURPOSE: To compare the accuracy of computed tomography (CT) and ultrasonography (US) in the diagnosis of acute appendicitis. MATERIALS AND METHODS: One hundred consecutive patients were examined with US and CT, and the results, independently reported, were correlated with surgical and histopathologic findings (69 patients) and data from other laboratory and clinical follow-up (31 patients). RESULTS: Fifty-four patients had acute appendicitis; 46 patients did not. Analysis of the data for CT and US, respectively, revealed sensitivity, 96% versus 76%; specificity, 89% versus 91%; accuracy, 94% versus 83%; positive predictive value, 96% versus 95%; and negative predictive value, 95% versus 76%. In the 46 patients without appendicitis, an alternative diagnosis was made with CT in 22 patients and with US in 15. CT scans showed abscesses and/or phlegmons in 28% of patients with appendicitis versus 17% at US. Results of CT and US were discordant in 20 patients; CT findings were correct in 17 and US findings in three. CONCLUSION: CT is more accurate than US in diagnosis of acute appendicitis.

Acute Disease↗
PubMed1994

Infectious esophagitis.

Infectious esophagitis is most often seen in patients with impaired host resistance. It has become a particular problem in the growing AIDS population. The three most commonly encountered opportunistic infections of the esophagus are Candida albicans, herpes simplex virus, and cytomegalovirus. Candida is the single leading cause of infectious esophagitis. Tuberculous and bacterial esophagitis and other unusual fungal infections of the esophagus are uncommon.

Candidiasis↗
PubMed1993

Neutrophil priming by lipopolysaccharide involves heterogeneity in calcium-mediated signal transduction. Studies using fluo-3 and flow cytometry.

Bacterial LPS is known to prime neutrophils for enhanced responses to subsequent stimulation by agonists such as FMLP. The purpose of this study was to determine whether priming is due to a uniform enhancement of function in all cells or to a recruitment of previously unresponsive neutrophils. Results from initial experiments confirmed the findings of other investigators and served to validate our methodology. We demonstrated that LPS-primed neutrophils had: 1) augmented superoxide anion production after FMLP or PMA stimulation; 2) increased FMLP-induced f-actin formation; 3) enhanced surface expression of CD11b, CD14, and the FMLP receptor; 4) caused higher baseline concentrations of intracellular calcium ([Ca2+]i); 5) caused greater elevations of [Ca2+]i after FMLP stimulation; and that 6) the priming effect of LPS on superoxide anion production and f-actin polymerization could be blocked by the [Ca2+]i chelator bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid. In subsequent experiments, we determined that at low concentrations of FMLP, LPS augmented the overall responsiveness of a population of neutrophils by causing a subpopulation of cells to become highly responsive and able to generate changes in [Ca2+]i upon low level stimulation. Heterogeneity in calcium-mediated signal transduction among neutrophils may be important in the fine control of the nonspecific immune system in response to weak environmental signals.

Actins↗
PubMed1993

Immune modulation of biologic systems in renal somatic cells.

The various theories discussed here suggest that somatic renal cells are susceptible to biologic modulation by the immune system independent of an inflammatory effect. (1) The mode of repression of type IV collagen synthesis by novel, soluble antigen-binding proteins, the down-regulation of class II MHC expression with interruption of antigen presentation to epithelia after selective gene regulation by antibody, and the diverse interactions of antibody with renal glomerular cells producing functional disturbances in endocytosis and permselectivity; (2) modification of surface-antigen composition; (3) alteration of matrix deposition, remodeling and composition; (4) biophysical perturbation of cytoskeletal and cell membrane components; (5) and lastly, alterations in cell adhesion through cell-surface alterations, all lend testimony to the richness of the signal transduction pathways in somatic cells. Although the preceding examples represent only a small fraction of those which may take place within the glomerular and tubular microenvironments, these paradigms may nevertheless serve as new models upon which one can consider the multitude of potential communications between disparate biologic systems that connect in complex organisms.

Animals↗
PubMed1992

Isolation and characterization of a NADP-dependent glutamate dehydrogenase gene from the primitive eucaryote Giardia lamblia.

Giardia lamblia is believed to be the earliest branching derivative from the eucaryotic lineage. Genomic and cDNA clones encoding the giardia NADP-dependent glutamate dehydrogenase have been isolated and characterized. Southern hydridization using genomic DNA indicates that the gene encoding this activity is unique and single copy. Primer extension, S1 nuclease protection, and genomic and cDNA sequence analysis demonstrate that gene transcripts are initiated within a conserved AT-rich sequence element immediately preceding the ATG translation initiation codon and the short 5' untranslated region is not extended by transsplicing. The open reading frame is 1350 nucleotides in length and encodes a protein of 449 amino acids. The reading frame is not interrupted by introns and the primary transcript is probably not subjected to RNA editing. In the strictly anaerobic metabolism of giardia, NADP-dependent glutamate dehydrogenase activity participates along with alanine aminotransferase, in the cyclic dissipation of reducing equivalents (NADPH) through the conversion of pyruvate to alanine. The deduced amino acid sequence of the giardia protein exhibits substantial homology to numerous fungal and eubacterial NADP-dependent glutamate dehydrogenases. Comparisons of alignment gap positions and amino acid identities indicate that the giardia sequence is at least as similar or more similar to the eubacterial sequence than it is to the fungal sequence. This supports the hypothesis that giardia diverged very early from the eucaryotic lineage.

Amino Acid Sequence↗
PubMed1992

Development of a monoclonal antibody-based p24 capsid antigen detection assay for HTLV-I, HTLV-II, and STLV-I infection.

A monoclonal antibody-based antigen capture enzyme-linked immunosorbent assay (ELISA) was developed and employed to detect p24 capsid antigen from human T-cell lymphotropic viruses type I and II (HTLV-I, HTLV-II), simian T-cell lymphotropic virus type I (STLV-I)-infected cell lines, and from mononuclear cell cocultures of HTLV-infected humans and STLV-I infected monkeys. A monoclonal antibody specific for HTLV p24 and p53 capsid antigens was coated onto 96-well microtiter plates to capture HTLV/STLV antigen. Captured antigen was then detected by the addition of a polyclonal, biotinylated human anti-HTLV-I antibody, and color developed with tetramethyl benzidine/H2O2 substrate. As little as 15 pg/ml of HTLV-I p24 antigen could be detected in this assay. Culture supernatants from HTLV-I-infected cell lines (HUT-102, MT-2, C5/MJ, HTLV-II-infected cell lines (Mo-T, Mo-B, PanG 12.1, NRA) and STLV-I-infected cell lines (Matsu, NEPC M39) were all positive in the assay. In addition, p24 was detected from peripheral blood mononuclear cell (PBMC) cocultures of 8 of 8 (100%) HTLV-I diseased patients, 14 of 20 (70%) HTLV-I and HTLV-II-infected, asymptomatic persons, and 8 of 8 (100%) STLV-I-infected, asymptomatic monkeys. Culture supernatants of cells infected with human immunodeficiency virus type (HIV-1), simian immunodeficiency virus (SIV), Chlamydia trachomatis, cytomegalovirus (CMV), herpes simplex I and II (HSV), feline leukemia virus (FELV), bovine leukemia virus (BLV), and bovine immunodeficiency virus (BIV) were all negative. Similarly, normal human peripheral blood mononuclear cells and uninfected, transformed human T cells, were also negative in the assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1992

Serologic confirmation of simian T-lymphotropic virus type I infection by using immunoassays developed for human T-lymphotropic virus antibody detection.

Serum specimens from diverse species of Old World monkeys, categorized as seropositive (n = 97) or seronegative (n = 23) for human T-lymphotropic virus (HTLV) infection, were tested by using recombinant env-spiked Western immunoblot assays and synthetic peptide assays for simultaneous detection and discrimination of simian T-lymphotropic virus (STLV) infection. Of the 97 seropositive specimens, 93 reacted with the recombinant transmembrane (r21env) protein and 90 reacted with a recombinant, MTA-1, derived from the central region of the external glycoprotein of HTLV-I (rgp46env), thus yielding test sensitivities of 96 and 93%, respectively. While 1 of the 23 negative monkey specimens reacted with r21env, none reacted with rgp46env, for overall specificities of 96 and 100%, respectively. Analysis of synthetic peptide-based immunoassays demonstrated that while 85 of 97 (88%) seropositive specimens reacted with HTLV-I-specific epitope (p19gag), none of the specimens reacted with HTLV-II-specific epitope (gp52env). These results show that recombinant envelope-spiked Western blots provide a simple means for serologic confirmation of STLV-I infection and that type-specific synthetic peptides can be used to confirm the virus type in seropositive monkey specimens.

Animals↗
PubMed1991

Crystal structure of defensin HNP-3, an amphiphilic dimer: mechanisms of membrane permeabilization.

Defensins (molecular weight 3500 to 4000) act in the mammalian immune response by permeabilizing the plasma membranes of a broad spectrum of target organisms, including bacteria, fungi, and enveloped viruses. The high-resolution crystal structure of defensin HNP-3 (1.9 angstrom resolution, R factor 0.19) reveals a dimeric beta sheet that has an architecture very different from other lytic peptides. The dimeric assembly suggests mechanisms by which defensins might bind to and permeabilize the lipid bilayer.

Amino Acid Sequence↗
PubMed1991

Indomethacin inhibition of middle ear bone resorption.

Localized osteoclastic bone resorption is responsible for the pathological changes within the middle and inner ear, which result in hearing loss and vertigo in chronic otitis media and otosclerosis. The local control of osteoclastic bone resorption is incompletely understood. Various small, locally active molecules, cytokines, have been shown to affect resorptive processes. Additionally, prostaglandins and their inhibitors have been shown to modulate the resorptive process in a number of in vitro studies. In this study, indomethacin, a cyclooxygenase inhibitor, was tested in a model of localized bone resorption, the pressurized gerbil bulla. After the experimental period, indomethacin was found to inhibit the number of osteoclasts and the resorptive area on the inner surface of the bulla. Therefore, it is likely that endogenous cyclooxygenase metabolites are intermediates in the sequence of cellular events, which results in localized bone resorption as in some systemic models.

Animals↗
PubMed1991

Clostridium difficile disease in a department of surgery. The significance of prophylactic antibiotics.

A clustering of Clostridium difficile-associated disease in a department of surgery prompted a program of infection control and the evaluation of contributing factors. Fifty patients had diarrhea and positive assays for C difficile cytotoxin during the study period. Twenty-one of the 36 cases that developed among patients admitted to the surgical services occurred on two adjacent general surgery wards that shared attending surgeons and house staff. Perioperative prophylactic antibiotics predated C difficile-associated disease in 20 patients, 12 of whom had short courses (less than 24 hours). Symptoms were typically nonspecific and early diagnosis may be difficult. Incidence remained high, despite infection control measures, until the coincidental closure of two surgical wards. Clostridium difficile-associated disease is a nosocomial infection that can be associated with short courses of prophylactic antibiotics. Recommendations regarding the use of perioperative prophylaxis should recognize C difficile-associated disease as a significant potential complication.

Adult↗