Burkitt's lymphoma cell lines have been important in vitro models for studying the pathogenesis of Burkitt's lymphoma (BL) and for exploring new treatment strategies. A new EBV(-) Burkitt's lymphoma cell line (GA-10) was established from a patient with a clinically aggressive, chemorefractory BL and characterized. Although functional p-glycoprotein could not be demonstrated by dye-efflux assays, both p53 genes were mutated in the GA-10 cells, perhaps contributing to the resistant phenotype of the original neoplasm. Two properties of BL cells which may be useful targets for novel cytotoxic therapeutics are their surface expression of CD77, the receptor for Shiga toxin (Stx), and their high rate of proliferation. Expression of CD77 on the GA-10 cells was heterogeneous in that certain subclones expressed high levels of CD77 and correspondingly exhibited strong growth inhibition by Stx while others showed low levels of CD77 expression and weak Stx-induced growth inhibition. Flavopiridol, a potent inhibitor of cell cycle progression through G1 and G2, induced cytotoxicity of the GA-10 cells with an LC(50) of approximately 40 nM vs 70 nM for HL-60 cells (P < 0.05). The concentrations of flavopiridol at which only 10% of the cells were viable (LC(10)) were approximately 280 nM for the GA-10 cells and 520 nM for the HL-60 cells (P < 0.05). Dose-related induction of apoptosis in response to flavopiridol was demonstrated in the GA-10 cells by morphology, TUNEL assay, and activation of caspase-3. Flavopiridol was also cytotoxic to seven other BL cell lines tested. These data suggest that flavopiridol may have therapeutic value in the treatment of Burkitt's lymphoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMedDate not supplied

The isolated major histocompatibility complex class I alpha3 domain binds beta2m and CD8alphaalpha dimers.

The MHC class I molecule plays a crucial role in cytotoxic lymphocyte function. The heavy chain of the MHC class I molecule can form many non-covalent interactions with other molecules on multiple domains and surfaces. We have generated an isolated alpha3 domain of a murine MHC class I molecule and evaluated the contribution of this domain to binding with the MHC class I light chain, beta2m, and CD8. The alpha3 domain binds beta2m at a thousand-fold higher concentration than the whole MHC, and binds CD8alphaalpha with a dependence on the alpha3 CD loop. Our results are relevant for models of MHC folding and CD8-MHC function. The study of individual domains of complex molecules is an important strategy for understanding their dynamic structure and function.

Binding Sites↗

PubMedDate not supplied

Spectrum of acute dissection of the ascending aorta: a transesophageal echocardiographic study.

Transesophageal echocardiography is an accurate tool for the immediate diagnosis of acute aortic dissection. In addition to establishing the diagnosis of dissection, transesophageal echocardiography provides determination of its extent and detection of complications. The purpose of this study was to delineate the full spectrum of abnormalities present in acute dissection of the ascending aorta as assessed by transesophageal echocardiography. Forty consecutive patients with acute ascending aortic dissection were evaluated. Specific attention was paid to complications of aortic valve insufficiency, pericardial effusion, and left ventricular wall motion abnormalities. The aortic arch and the descending aorta were also evaluated for involvement. Quantitative data included measurement of the aorta at the anulus, sinuses, and tubular portion, as well as the proximal and distal descending aortas. An intimal flap was identified in all patients. This was a simple linear tear in 22 patients (55%) and circumferential in eight (20%). A complex tear was noted in 10 patients (25%). The majority of patients (n = 30; 75%) had extension of the dissection into the descending thoracic aorta. At least one communication between the true and false lumens ("entrance point") was identified in 31 patients (78%). Pericardial effusions were noted in 19 patients (48%), only two of whom had a moderate-size effusion. Moderate or severe aortic insufficiency was seen in 18 patients (45%) and regional wall motion abnormalities in six patients. We conclude that acute dissection of the ascending aorta results in a complex or convoluted flap rather than a simple linear tear in many patients. The complication of clinically significant pericardial effusion was rare. Aortic insufficiency is common and can be attributed to multiple mechanisms.

Acute Disease↗

PubMedDate not supplied

Fluorescent-labeled poly(ethylene glycol) lipid conjugates with distal cationic headgroups.

The synthesis of a new class of fluorescent cationic poly(ethylene glycol) lipid conjugates (CPLs) is described. These lipids consist of a hydrophobic distearoyl-phosphatidylethanolamine (DSPE) anchor coupled to a highly fluorescent N(epsilon)-dansyl lysine moiety, which is attached to a hydrophilic poly(ethylene glycol) (PEG) spacer that is linked to a cationic headgroup made of lysine residues. Introduction of the dansyl moiety allows rapid and accurate quantification of CPLs within lipid bilayers using fluorescence techniques. The synthetic scheme is straightforward, using repeated amino-carboxyl coupling reaction steps, with purification by precipitation. A series of dansylated CPLs was synthesized with zero, one, three, and seven lysine residues located at the distal end of the PEG chain, giving rise to CPLs with one, two, four, and eight distal positive charges, respectively. The structures of the CPLs were confirmed by (1)H NMR spectroscopy and chemical analysis. CPLs provide a means of introducing positive charge to a bilayer that is localized some distance from the membrane surface, and are of particular interest for nonviral gene delivery applications. The usefulness of CPLs is demonstrated by the enhanced in vitro cellular binding and uptake of liposomes containing CPL(4).

Cations↗

PubMedDate not supplied

Free radical oxidation of (E)-retinoic acid by prostaglandin H synthase.

Cooxidative metabolism of all-trans (E)-retinoic acid (RA) by prostaglandin H synthase was investigated employing ram seminal vesicle microsomes (RSVM) or purified, RSVM-derived enzyme. RA was shown to undergo hydroperoxide [H2O2 or 5-phenyl-4-penten-1-yl hydroperoxide (PPHP)]- or arachidonic acid-dependent cooxidation by microsomal prostaglandin H (PGH) synthase as evidenced by UV spectroscopic analysis of reaction mixtures. Cooxidation of RA by microsomal or purified PGH synthase, using PPHP as substrate, was characterized by uptake of dioxygen which was first order with respect to enzyme concentration. Dioxygen uptake was inhibited by the peroxidase reducing substrate 2-methoxyphenol. In addition, O2 uptake was inhibited by the spin trap nitrosobenzene. ESR spin trapping studies, using alpha-phenyl-N-tert-butylnitrone (PBN) as the spin trap, demonstrated the formation of RA-PBN adducts, characterized by hyperfine coupling constants of alpha H = 3.2 G and alpha N = 15.8 G. Reverse phase HPLC analysis of reaction mixtures demonstrated the formation of 4-hydroxy-RA, 5,6-epoxy-RA, 4-oxo-RA, (13Z)-retinoic acid, and other geometric isomers which were identified on the basis of cochromatography with synthetic standards, UV spectroscopy, and/or mass spectrometry. Mechanisms are proposed for the hydroperoxide-dependent, PGH synthase-catalyzed oxidation of RA that are consistent with these results.

Animals↗

PubMedDate not supplied

Quantification analysis for saccadic eye movements.

Traditional parameters, such as latency and peak velocity, have been used for quantitative analysis of saccade dynamics. However, saccades of equal magnitude which differ substantially in dynamics may still have the same peak velocity. This lack of selectivity might degrade the efficacy of the peak velocity measurement in discriminating patients from normal subjects. In this study, an alternative parameter, the damping ratio of a second-order response, is proposed to concisely and accurately describe saccadic dynamics. A measurement of damping ratio is made by considering the response curve of saccade as the step response of a second-order transfer function. Using the least-mean-square algorithm, the second-order function has been optimized to fit the response of the saccade dynamics with the latency removed. Nineteen normal subjects (ten young and nine older) and 16 patients of Parkinson's disease (eight mildly affected and eight advanced affected) were tested for eye movements in response to pseudorandom saccadic stimuli. While the traditional peak velocity had difficulties in differentiating between the saccadic dynamics of normal and Parkinson subjects, the damping ratio is sensitive enough not only to highlight the difference between a group of patients mildly affected with Parkinson's disease and an age-matched normal group (p<0.01; abnormal versus normal), but also to distinguish between groups at different ages (p<0.01; younger versus older). It is proposed that the damping ratio could be a useful parameter in analyzing saccadic dynamics.

Adult↗

PubMedDate not supplied

Mononuclear cell response to enterobacteria and Gram-positive cell walls of normal intestinal microbiota in early rheumatoid arthritis and other inflammatory arthritides.

OBJECTIVE: To study whether enterobacteria and Gram-positive bacterial cell walls (BCW) derivedfrom normal intestinal microbiota are involved in the etiopathogenesis of early rheumatoid arthritis (RA). METHODS: Peripheral blood mononuclear cells (PBMC) and synovial fluid mononuclear cells (SFMC) were isolatedfrom patients with early RA (the average duration of 5 months) and the controls (other types of inflammatory arthritis). The mononuclear cell proliferation and tumor necrosis factor-alpha (TNF-alpha) responses to heat-killed Salmonella enteritidis (SE). Yersinia enterocolitica (YE), and Escherichia coli (EC), and to Gram-positive BCW derived from four common intestinal indigenous bacteria, Eubacterium aerofaciens (EA), Eubacterium limosum (EL), Lactobacillus casei (LC), and Lactobacillus fermentum (LF), and a BCW derived from a pathogen, Streptococcus pyogenes (SP) were investigated. RESULTS: 39% or 56% of patients with early RA showed significant proliferation responses by PBMC or SFMC against enterobacteria, respectively. In other types of arthritis, corresponding figures were 59% or 66%. When BCW were used as antigens, 8.1% or 23% of patients with early RA showed proliferation responses by PBMC or SFMC, respectively. In other types of arthritis the corresponding figures were 7.5% or 35%, respectively. However, TNF-alpha production by SFMC stimulated by EA BCW, SE, YE or EC, was significantly higher in early RA than in other types of arthritis. CONCLUSION: These results suggest that SFMC reacting with enterobacteria or BCW exist in some patients with early RA, but also in other types of inflammatory arthritis. Intestinal bacterial agents may play a role in the etiopathogenesis of RA, but the effect appears to be non-specific.

Adolescent↗

PubMedDate not supplied

CD26.

Explore the source record for details and available documents.

Adenosine Deaminase↗

PubMedDate not supplied

Frequency of Salmonella enteritidis and other salmonellae in the ceca of spent hens at time of slaughter.

A study was conducted to determine the frequency of Salmonella enteritidis (SE) and other Salmonella serovars in the cecal contents of spent laying hens at a hen-processing plant in the southeastern United States over a 4 1/2-month period, from October 1990 through February 1991. A total of 1920 pooled cecal samples (three ceca per sample) from 38 flocks representing 23 producers were obtained and tested for the presence of SE and other Salmonella serovars. A total of 359 samples (18.7%) from 37 of the 38 flocks (97.4%) showed characteristic reactions for salmonellae on triple sugar iron agar (TSIA) slants. Twenty-nine of the 359 Salmonella-positive samples (8.1%) were Group D-positive, all of which were found to be SE on further serotyping. The SE-positive samples were from seven of the 38 flocks (18.4%); four flocks originated from the USDA/APHIS-designated Northern Region of the United States, and three were from the Southeastern Region. Serotyping of the 330 TSIA-positive Group-D negative Salmonella revealed 37 different serovars. S. heidelberg, the predominant serovar, was identified in 49.1% of these isolates.

Abattoirs↗

PubMedDate not supplied

Stable isotope analysis by fast-atom bombardment labeling of UDP-glucuronic acid.

Fast-atom bombardment mass spectrometry is found to provide a method for analysis of isotopes in the enzyme cofactor uridine-5'-diphosphoglucuronic acid, heretofore unsusceptible to mass-spectral characterization. This technique was used to determine optimal conditions for the introduction of 18O by acid-catalyzed exchange in H218O and to evaluate the loss of the isotope when labeled cofactor is used in enzymatic incubations. Fast-atom bombardment mass spectrometry provided a quantitative assessment of various isotopic species and also permitted the location of the isotopes in the molecule to be determined.

Mass Spectrometry↗