Biomedical subjects

P Dilda

Publications and source records attributed to P Dilda.

8 recordsLinked to original sources

PubMed2001

Distance learning in the digital environment.

The expansion of radiology departments and divisions often can not occur in adjacent geographic locations. This leads to a greater separation of staff and residents, as well as workers in similar divisions. This makes traditional teaching difficult in academic institutions. The economic drive forcing many departments to investigate more isolated outpatient imaging centers has further hindered the ability to continue effective academic training at many facilities. The ability to easily share a digital environment across physical distance can greatly enhance the teaching experience, as well as be a valuable tool for consultation and case discussion with referring clinicians. The transition to a filmless environment with picture archiving and communication systems (PACS) can be utilized for distance learning in addition to the clinical arena. It is possible to take advantage of the digital transformation to PACS and case-viewing browser programs to conduct improved interactions with referring clinicians as well as radiologic teaching with relatively minimal hardware and software demands. The integration of web-based teleradiology programs with business networking software can be used for effective distance learning in the digital environment, sufficiently closing the distance on our rapidly expanding departments. This same technology allows for greater interaction with referring clinicians for real-time consultation and enhanced case discussion to entrench a supportive referral base for the radiologic community.

Humans↗

PubMed2001

The evolution of filmless radiology teaching.

PURPOSE: The transition from hard-copy film to the picture archiving and communication systems (PACS) arena is often a long and difficult path, but the complete transformation to the digital environment does not end with the successful clinical practice utilizing PACS. The next hurdle for academic institutions is similar changes in the teaching field. The loss of hardcopy films can greatly hinder the radiology teaching file and teaching conference experiences. The next step in our growth is the conversion to digital teaching files and conferences. The original work 10 years ago with utilizing computers linked with laser disks and magneto-optical media, have now evolved into complex networks with expanding and relatively cheap storage media, such as CD-ROM and easily to navigate graphic-user interfaces such as hypertext markup language (HTML) and extensible markup language (XML), for use with multimedia teaching tools. CONCLUSIONS: The transition into the digital arena for radiology education and interdepartmental conferences can be accomplished through several different paths. These include direct transfer of images into a presentation program, as well as exportation of images into suitable image file formats for later use. There is also the ability to expand the PACS network to include conference rooms. Similar training and teaching can allow radiologists to transition into the digital environment for future digital teaching file creation as well as correlative radiology interdepartmental conferences.

Computer-Assisted Instruction↗

PubMed2001

Synthesis and anti-HIV activity of thymidine analogues bearing a 4'-cyanovinyl group and some derivatives thereof.

Treatment of 3'-O-tert-butyldimethylsilyl-2',5'-dideoxy-5'-oxothymidine (4) with potassium or magnesium nitromethanide afforded in good yield the resolvable epimeric mixture of the expected blocked nitronucleosides 5 which upon dehydration led to the corresponding E-nitroenofuranosylthymidine 6. Nucleophilic attack of cyanide onto the nitrovinyl group led to a nucleoside analogue bearing a terminal 1-cyanovinyl group (7), a soft electrophilic group which, upon reaction with benzeneselenol, underwent a conjugate addition to the phenylselenonucleoside derivative 9. All these compounds, eventually de-O-silylated, were subject of in vitro biological testing, some exhibiting interesting cytotoxic or antiviral properties.

Animals↗

PubMed2000

Highly stereoselective synthesis and biological properties of nucleoside analogues bearing a spiro inserted oxirane ring.

Starting from 2',5'-di-O-TBDMS-3'-ketouridine 1 or its thymine analogue 2, both xylo (3-10) and ribo (20) epimers of a series of 3"-substituted 3'-spironucleosides have been obtained in good yields and with a total stereoselectivity. Most new compounds were moderately cytotoxic with in some cases slightly selective antiproliferative activities. None of these compounds was active against HIV, but some other antiviral activities against HSV-2, CMV, EBV, or VZV, in the micromolar range, were noted in specific cases.

Antibody-Dependent Cell Cytotoxicity↗

PubMed2000

Synthesis and antiproliferative activity of O-silylated nucleoside triazene N-oxide derivatives.

A series of modified nucleosides bearing at varied positions of the sugar moiety one 3-aryl-1-triazeno N1-oxide group and a variable number of O-TBDMS groups have been prepared and their cytotoxicities and cytostaticities measured on different cell lines. Nucleosides bearing an aryltriazeno N-oxide group and O-TBDMS groups are either devoid of cytotoxicity or possess a selective cytotoxicity. On the other hand, nucleosides bearing one triazeno group and no silyl group are devoid of cytotoxicity and silylated nucleosides without triazeno group are generally either devoid of cytotoxicity or unselectively cytotoxic. This indicates that the O-TBDMS group per se is not cytotoxic.

Animals↗

PubMed1998

Alterations of ionic membrane permeabilities in multidrug-resistant neuroblastoma x glioma hybrid cells.

A population of NG108-15 neuroblastoma cells resistant to doxorubicin (NG/DOXR) was established. The cells exhibited a multidrug resistance phenotype with cross-resistance to vinblastin and colchicine, overexpression of a 170 kDa membrane protein identified as P-glycoprotein and reversal of resistance by verapamil and quinine. Compared with NG108-15 cells, NG/DOXR cells showed an increase in Na+ current density and a decrease in cyclic-AMP-activated Cl- current density with no change in K+- and volume-sensitive Cl- current densities. As previously observed in NG108-15 cells, the vacuolar-type H+-ATPase inhibitors bafilomycin A1 and nitrate induced membrane depolarizations in NG/DOXR cells. The resting potentials of sensitive and resistant cells were not significantly different, but the depolarizations evoked by these agents were significantly larger in NG/DOXR than in NG108-15 cells. The resting membrane potential of NG/DOXR cells, but not that of NG108-15 cells, was depolarized by verapamil, and this effect was abolished by bafilomycin. The volume-sensitive Cl- currents of drug-sensitive and drug-resistant cells were inhibited by a decrease in intracellular pH from 7.3 to 6.8. Whereas bafilomycin prevents activation of Cl- currents in both drug-sensitive and drug-resistant cells, verapamil inhibited the Cl- current only in NG/DOXR cells. The results are discussed in terms of the roles of cytoplasmic pH and membrane potential in multidrug resistance.

Animals↗

PubMed1994

Functional characterization of cystic fibrosis transmembrane conductance regulator (CFTR) in apical membranes purified from bovine tracheal epithelium.

Inside-out apical membrane vesicles were isolated from bovine tracheal epithelium. They were enriched 13- and 18-fold in two apical membrane markers, alkaline phosphatase and gamma-glutamyltransferase, respectively, and presented a low level of contamination by basolateral and intracellular membranes. These apical membrane vesicles of homogeneous inside-out orientation were used to measure 36Cl- influx. The 36Cl- influx was found to be (i) voltage-insensitive (ii) diphenylcarboxylic acid-insensitive, and (iii) from 55 to 100% activated by cAMP-dependent protein kinase according to initial rates and accumulation capacities. This rapid and ATP-dependent activation was associated with phosphorylation of a 170-180-kDa protein but was not observed with a nonhydrolyzable nucleotide like adenosine 5'-O-(3-thiotriphosphate). Immunodetection experiments showed that the mature form of bovine cystic fibrosis transmembrane conductance regulator (CFTR) was only present in the apical membranes. As compared with the previously described characteristics of CFTR, the 36Cl- uptakes detected here are the in vitro manifestation of the functional form of bovine CFTR located at the apical level in these tracheal epithelial cells. Inside-out apical membrane vesicles, with freely accessible cytoplasmic sides and functional CFTR, offer a new model system to study CFTR.

Animals↗

PubMedDate not supplied

Consequences of ddI-induced reduction of acute SIVmac251 virus load on cytokine profiles in cynomolgus macaques.

This study evaluates the consequences of antiretroviral treatment of the acute simian immunodeficiency virus (SIV) primary infection on virus load and cytokine responses. Four cynomolgus macaques were inoculated intravenously with a pathogenic primary isolate (SIVmac251). Animals were pretreated with 10.8 mg/kg/day of dideoxyinosine (ddI) from 4 days before inoculation, and treatment was continued for 28 days. Proinflammatory (IL6, IL1 beta and TNF alpha) and antiinflammatory (IL10) cytokine and lymphokine (IL2, IL4 and IFN gamma) polymerase chain reaction (PCR) ratios were monitored in unmanipulated peripheral blood mononuclear cells (PBMCs) during acute infection by using a semiquantitative reverse transcription (RT)-PCR method. PBMC-associated virus loads were dramatically reduced compared to those of placebo-treated macaques. Nevertheless, a transient rise in IL6, IL1 beta, TNF alpha and IL10 mRNA expression was observed in PBMCs. IL2, IL4 and IFN gamma mRNAs were either undetectable or weakly detectable throughout the study, with no major changes. Despite a dramatic reduction in the acute viral loads in ddI-treated monkeys, early cytokine mRNA profiles were comparable to those of untreated SIVmac251-infected monkeys. Contrary to what was previously evidenced during primary infection with an attenuated SIV clone, no increase in IL2 and IL4 mRNA was detected in PBMCs of the ddI-treated monkeys, although these monkeys exhibited virus loads similar to those evidenced in macaques infected by attenuated SIV. These data indicate that differential lymphokine expression patterns found in pathogenic and Nef-truncated SIV-infected monkeys may not be strictly dependent on virus load levels.

Acute Disease↗