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At least 397 records · Page 22Linked to original sources
PubMed1994

Prototypical HTLV-I/II infection is rare in LGL leukemia.

The etiology of LGL leukemia is not known; however, we recently detected HTLV-II in a patient with LGL leukemia. In this study, we found that sera from 6 of 28 patients with LGL leukemia were positive for HTLV-I/II using a whole virus ELISA; moreover, the ELISA-negative sera were near the positive cut-off value. Therefore, we performed additional studies on these sera using commercially available assays which can confirm and distinguish HTLV-I from HTLV-II infection. Serum from only one patient was confirmed positive using conventional criteria (HTLV-II+). Sera from 25 patients (89%) had indeterminate reactivity on Western blot assays. Of these, sera from 21 (84%) reacted to gag protein p24; 12 (48%) reacted with recombinant env protein p21e, and 10 (40%) reacted with both. We could not detect HTLV-I/II pol or pX gene sequences in these patients using polymerase chain reaction analyses, with the exception of the HTLV-II-infected patient described previously. These data show that most patients with LGL leukemia are not infected with prototypical HTLV-I or HTLV-II. The frequent reactivity of patient sera to HTLV-I/II gag protein p24 and to env protein p21e, however, suggests that a deleted or variant form of HTLV-I/II may be associated with LGL leukemia.

Blotting, Western↗
PubMed1991

Dynamic monitoring of [11C]diprenorphine in rat brain using a prototype positron imaging device.

The present work tests the feasibility of using the most recently developed positron emission tomograph detector technology to image positron-emitting radioligands in small experimental animals. A prototype imaging device, using two opposing multicrystal, high-resolution (approximately 4 mm) block detectors of bismuth germanate to produce a 2-dimensional image in the centre of the field of view, is described. To evaluate the probe's potential as a non-invasive experimental tool, the dynamic regional distribution of the established opiate receptor ligand, [11C]diprenorphine was determined in rat brain following intravenous injection. The distribution of counts in the images was consistent with the localisation of diprenorphine binding sites and the specificity of the signal obtained was confirmed by administration of non-radioactive diprenorphine and naloxone. Although the signal-to-noise ratio was reduced compared with data obtained by post mortem dissection, the dynamic data acquisition capabilities of the system demonstrate the feasibility of monitoring the kinetics of ligand binding in individual animals and encourages further design of a small-diameter detector system with tomographic capabilities.

Animals↗
PubMed1985

A comparison of the susceptibility of three human gut tumour-derived differentiated epithelial cell lines, primary monkey kidney cells and human rhabdomyosarcoma cell line to 66-prototype strains of human enteroviruses.

The growth of prototype strains of 31 serotypes of ECHO, 3 polio, 6 Coxsackie B, 24 Coxsackie A and enterovirus serotypes 70 and 71 were tested in parallel in primary monkey kidney cells (PMK), RD cells and three gut tumour-derived differentiated epithelial cell lines (HRT-18 HT-29 in SKCO-1). All 31 serotypes of ECHO viruses grew in HT-29, 27 and SKCO-1, 5 in HRT-18, 29 in PMK and 29 in RD. There was good growth of poliovirus serotypes in all five cell types. Coxsackie B viruses grew well in all the cell lines except RD. Fifteen of the Coxsackie A viruses grew in SKCO-1, 4 in HT-29, 3 in HRT-18 and 7 in RD. Enterovirus serotypes 70 and 71 grew only in RD cells after 3 serial passages. These results showed that 2 of the gut tumour-derived cell lines, HT-29 and SKCO-1 had a markedly wider susceptibility, with comparable or wider sensitivity, for enteroviruses, than PMK and RD. While their use for field isolation from clinical samples is not yet fully established HT-29 and SKCO-1 would appear to be ideal for a variety of laboratory manipulations of the majority of enteroviruses.

Animals↗
PubMed1992

Restriction analysis of the prototype strain of enteric adenovirus type 41 using exonuclease III.

Enteric adenoviruses 40 and 41 (Ad40 and Ad41) are a prominent cause of gastroenteritis in young children. Diagnosis of these enteric types by conventional means is complicated by their fastidious growth characteristics. Enteric adenovirus growth was enhanced by cocultivation. Typing of enteric isolates currently entails analysis of the extracted viral DNA with restriction enzymes. Restriction endonuclease fragments of the Ad41 strain Tak genome were ordered by (i) double digestion, (ii) release of restriction fragments from plasmids containing 84% of the Ad41 genome in EcoRI fragments A, B and C, (iii) hybridization of Southern blotted Ad41 fragments with EcoRI fragment containing plasmids and various segments of the Ad2 genome, (iv) sequential reduction of the genome beginning with terminal restriction fragments with exonuclease III and S1 nuclease. The termini of adenovirus genomes are difficult to clone and the use of exonuclease III is a useful alternative to conventional restriction mapping. DNA restriction patterns, fragment sizes and restriction maps of the Ad4 1 strain Tak with enzymes BamHI, BglII, ClaI, EcoRI, HindIII, PstI, SalI, SmaI and XhoI are presented. Prototype strain restriction maps should enable better understanding of adenovirus type 41 and its epidemiology.

Adenoviruses, Human↗
PubMed1992

The heterodimer calmodulin: myosin light-chain kinase as a prototype vertebrate calcium signal transduction complex.

The heterodimer complex of calmodulin (CaM) and the protein kinase catalytic subunit of myosin light chain kinase from vertebrate smooth muscle and non-muscle tissues (sm/nmMLCK) is one of the most extensively characterized CaM-regulated enzyme complexes and it has an established in vivo role in the transduction of calcium signals into biological responses. We have used a combination of approaches to the study of CaM and sm/nmMLCK in order to derive initial insight into the key features of each protein and of the CaM-MLCK heterodimeric complex that are involved in protein-protein and calcium-protein recognition and regulation of enzyme activity. On-going studies are described here that include site-specific mutagenesis, fluorescence spectroscopy, enzymology and peptide analog analysis. These and previous results indicate that: (1), both electrostatic and hydrophobic features are important in the functionally correct interactions between CaM and MLCK; (2), even the interactions between CaM and peptide analogs of the CaM binding site of MLCK are heterogeneous and non-trivial in nature; (3), amino-acid residues that have been conserved in CaM across millions of years of evolution and that are conserved in CaMs with quantitative MLCK activator activity can be mutated without any detectable effect on activity and (4), structures different from the prototypical EF-hand domain of CaM can have similar calcium-binding activity in the presence of a CaM binding structure.

Amino Acid Sequence↗
PubMed1996

Growth characteristics and protein profiles of prototype and wild-type rat coronavirus isolates grown in a cloned subline of mouse fibroblasts (L2p.176 cells).

Rat coronaviruses (RCVs) infect laboratory rats and confound biomedical research results. In vitro systems developed so far have limited the growth in knowledge about RCVs by not permitting generation of plaque-cloned virus stocks, reliable isolation of RCVs from rat tissues, or growth of high titered stocks of all isolates. Due to the fact that less than 20% of L2(Percy) cells were becoming infected, sublines were produced and selected for maximal growth of RCVs. Screening of 238 cell sublines yielded L2p.176 cells which were highly susceptible to all RCVs tested; however, susceptibility declined after 30 passages in vitro. Low-passaged L2p.176 cells were used to isolate virus from natural outbreaks and to propagate individual RCV plaques into high titered stocks. Proteins from six RCV isolates were immunoblotted using polyclonal rat and mouse antibodies to sialodacryoadenitis virus and polyclonal monospecific rabbit and goat antibodies against the peplomer (S) and nucleocapsid (N) proteins of mouse hepatitis virus (MHV). Proteins of two prototype, one Japanese and three wild type RCVs were examined and found to be similar to those of MHV, although the exact sizes and ratios of protein forms were unique for most RCV isolates. This study reports the development of a continuous cell line which reliably supports RCVs opening an opportunity for further in vivo studies of the biology of these agents. As a first step in the characterization of RCVs, we have shown that RCV proteins are very similar to those of MHV.

Animals↗
PubMed1989

The principles and prototyping of a knowledge-based diabetes management system.

This paper describes the principles and prototyping of a computer-based system being developed to assist in the management of diabetes mellitus. Unlike other approaches based upon mathematical modelling or the use of computer algorithms, this system adopts one derived from artificial intelligence, seeking to incorporate the dynamics of glucose and insulin in a manner which reflects their clinical importance. The resultant logical model (qualitative algebra) defines the relationships between changes in insulin dose and site and time of injection and glycaemic response. In this manner the computer-based system, implemented in Prolog, can be used to provide advice concerning insulin therapy by means of making qualitative predictions of patient outcome of blood glucose profile resulting from alternative insulin regimens.

Blood Glucose↗
PubMed1993

Intestinal antibody response after oral immunization with a prototype cholera B subunit-colonization factor antigen enterotoxigenic Escherichia coli vaccine.

A prototype oral enterotoxigenic Escherichia coli (ETEC) vaccine containing formalin-inactivated whole bacteria expressing colonization factor antigens CFA/I and CFA/II and cholera B subunit (CTB) has been tested for safety and immunogenicity in 20 adult Swedish volunteers. When given in three doses with 2-week intervals the vaccine was found to be safe and to give rise to specific IgA antibody responses in intestinal lavage fluid in most of the volunteers (CFA/I 82%, CFA/II 82% and CTB 91%). The frequencies and magnitudes of these responses, which were already maximal after two doses, were comparable with those previously found in patients convalescing from severe ETEC diarrhoea. All the vaccinated volunteers also responded with antitoxin IgA as well as IgG antibodies in serum, whereas the serum antibody responses against the CFAs were weaker and mainly of the IgA isotype.

Administration, Oral↗
PubMed1995

Safety and immunogenicity of a prototype oral whole-cell killed Campylobacter vaccine administered with a mucosal adjuvant in non-human primates.

The safety and immunogenicity of two prototype oral Campylobacter killed whole-cell (CWC) vaccines were tested in rhesus monkeys. Animals were immunized with a primary two-dose series (days 0 and 14) of vaccine consisting of CWC (10(10) particles/dose) given alone or in combination with 0.5-1000 micrograms of the heat-labile enterotoxin of Escherichia coli as an oral adjuvant (OA). A booster vaccination, 4 weeks after primary immunization, was given to animals receiving CWC alone or supplemented with 0.5, 5 or 50 micrograms of OA. Both CWC and CWC-OA were well tolerated, with no adverse side-effects noted. Campylobacter-specific as well as adjuvant-specific antibody-secreting cells (ASCs) were determined in peripheral blood collected 7 days after each vaccine dose. Campylobacter-specific IgA ASC responses were enhanced by OA in a dose-dependent manner (p = 0.025), while IgG ASC responses were not. Seroconversions (both IgA and IgG) to Campylobacter antigens were also enhanced in monkeys receiving adjuvanted vaccine. No significant booster vaccination effect was observed in circulating ASCs in any of the immunization groups. In vitro T-cell proliferative responses to Campylobacter jejuni antigens were somewhat enhanced in both the CWC and CWC-OA immunization groups. These results demonstrate that CWC-OA is safe and superior to CWC alone in its ability to stimulate both local and systemic Campylobacter-specific IgA and IgG responses in primates and they support its further evaluation in human clinical studies.

Adjuvants, Immunologic↗
PubMed1992

Biosphere 2: a prototype project for a permanent and evolving life system for Mars base.

As part of the ground-based preparation for creating long-term life systems needed for space habitation and settlement, Space Biospheres Ventures (SBV) is undertaking the Biosphere 2 project near Oracle, Arizona. Biosphere 2, currently under construction, is scheduled to commence its operations in 1991 with a two-year closure period with a crew of eight people. Biosphere 2 is a facility which will be essentialy materially-closed to exchange with the outside environment. It is open to information and energy flow. Biosphere 2 is designed to achieve a complex life-support system by the integration of seven areas or "biomes"--rainforest, savannah, desert, marsh, ocean, intensive agriculture and human habitat. Unique bioregenerative technologies, such as soil bed reactors for air purification, aquatic waste processing systems, real-time analytic systems and complex computer monitoring and control systems are being developed for the Biosphere 2 project. Its operation should afford valuable insight into the functioning of complex life systems necessary for long-term habitation in space. It will serve as an experimental ground-based prototype and testbed for the stable, permanent life systems needed for human exploration of Mars.

Air Conditioning↗
PubMed1995

The frog taste disc: a prototype of the vertebrate gustatory organ.

The frog taste disc (TD) is apparently the largest gustatory organ found in vertebrates and seems to differentiate into a specialized variety of the prototypic scheme of the taste bud. An explanation for this unusual organization is lacking although it is possible to speculate the existence of environmental and nutritional requirements. Up to the present time, the most common model of the TD was based on two main cell types (sensory and sustentacular). This model may oversimplify the morphology of this structure since more numerous cell types have been described. We now propose a new model of the TD, based on comprehensive data on the ultrastructure of the organ obtained in the last 20 years. The main conclusions are the following: (1) the TD is a pluristratified epithelium with a general organization similar to that of the olfactory and vomeronasal epithelium; (2) it has skeleton composed of three different types of epithelial cells; (3) the chemoreceptorial surface is covered by different microenvironments; (4) three different types of neuro-epithelial systems are present; the type II is an 'open' sensory cell with axonal contacts devoid of vesicles; the type III is an 'open' sensory cell with synaptic-like junctions; the type i.v. is a 'closed' sensory cell with a 'Merkel-neurite complex'; (5) the nerve fibers in the basal plexus are mostly cholinergic while the peridiscal nerve fibers are mostly peptidergic. The presence of several cell types in the TD must be considered using these large receptors in electrophysiological studies or as a source of isolated cells, and their complexity must induce caution in the interpretation of the data. Text books of histology usually describe the peripheral structures associated with taste as very simple: an idea that probably must be revised. A taste organ is a highly complex structure composed of several sensory systems and a comparative approach can aid comprehension of its general organization. The study of the 'large taste organs' present in some species of amphibians can provide useful data for knowledge of the gustatory system of vertebrates.

Animals↗
PubMed1989

A digital annular array prototype scanner for realtime ultrasound imaging.

The use of annular array transducers in diagnostic ultrasound applications is growing. The development of this equipment raises a number of questions concerning both the role these systems will play in the clinic and how the annular array can be best implemented in an ultrasound scanner. In this paper, we will build on the results of the previous companion paper to describe the development of a 12 element 30 mm diameter 4.5 MHz laboratory prototype scanner. The mechanical probe and probe acoustics are discussed and a unique digital receive beamformer (DRB) and signal processor are described. Focusing down to an f-number (focal length/diameter) of 0.9 is demonstrated. Measured angular beamwidths of 0.62 degrees at -6 dB and 2.8 degrees at -50 dB are in good agreement with theoretical predictions. Images of phantoms and normal volunteers showed exceptional resolution with little variation in the fine speckle texture as a function of depth. The effect of the number of transmit focal zones on image quality is demonstrated.

Equipment Design↗
PubMed1986

The bacteriorhodopsin model membrane system as a prototype molecular computing element.

The quest for more sophisticated integrated circuits to overcome the limitation of currently available silicon integrated circuits has led to the proposal of using biological molecules as computational elements by computer scientists and engineers. While the theoretical aspect of this possibility has been pursued by computer scientists, the research and development of experimental prototypes have not been pursued with an equal intensity. In this survey, we make an attempt to examine model membrane systems that incorporate the protein pigment bacteriorhodopsin which is found in Halobacterium halobium. This system was chosen for several reasons. The pigment/membrane system is sufficiently simple and stable for rigorous quantitative study, yet at the same time sufficiently complex in molecular structure to permit alteration of this structure in an attempt to manipulate the photosignal. Several methods of forming the pigment/membrane assembly are described and the potential application to biochip design is discussed. Experimental data using these membranes and measured by a tunable voltage clamp method are presented along with a theoretical analysis based on the Gouy-Chapman diffuse double layer theory to illustrate the usefulness of this approach. It is shown that detailed layouts of the pigment/membrane assembly as well as external loading conditions can modify the time course of the photosignal in a predictable manner. Some problems that may arise in the actual implementation and manufacturing, as well as the use of existing technology in protein chemistry, immunology, and recombinant DNA technology are discussed.

Bacteriorhodopsins↗
PubMed1989

The effect of prototypic sigma ligands on the binding of [3H]dextromethorphan to guinea pig brain.

We studied the effects of several prototypic sigma site ligands on the binding of [3H]dextromethorphan ([3H]DM) to guinea pig brain. Haloperidol, 3-(-3-Hydroxyphenyl)-N-(1-propyl)piperidine [+)-3-PPP) and (+)-N-allyl-N-normetazocine [+)-NANM or (+)-SKF10,047), which are potent sigma site ligands, showed high affinity for [3H]DM binding sites. The rank order of potency of sigma ligands, as indicated by the Ki values for the high-affinity sites is: haloperidol greater than (+)-pentazocine greater than (+)-cyclazocine greater than (+)-SKF10,047 greater than (-)-butaclamol much greater than (+)-butaclamol greater than (-)-SKF10,047. This rank order of potency is similar to that for the sites labeled with [3H](+)-3-PPP and [3H](+)-SKF10,047. The (+)-isomers of several benzomorphans displayed higher affinity than the (-)-isomers. (-)-Butaclamol competed against [3H]DM binding more effectively than the (+)-isomer, displaying the same stereospecificity shown for sigma sites. The findings reported here demonstrate that there are previously unrecognized similarities between DM and sigma sites. It is evident that further exploration of the DM, sigma and phencyclidine (PCP) sites will be necessary to establish the physiological role and therapeutic potential of these sites.

Animals↗
PubMed1987

Dosimetry studies on prototype 241Am sources for brachytherapy.

Sealed sources of 241Am emit primarily 60 keV photons which, because of multiple Compton scattering, produce dose distributions in water that are comparable to those from 226Ra or 137Cs. However, americium gamma rays can be shielded by thin layers of high atomic number materials since the half value layer thickness is only 1/8th of a mm of lead for americium gamma rays as compared to a value of 12 mm for 226Ra gamma rays. This may allow effective in vivo shielding of critical organs, for example; the bladder can be partially shielded by hypaque solution, and the rectum and sigmoid colon by barium sulfate. In addition, the exposure to medical personnel involved in intracavitary application and patient care may be reduced substantially by the use of relatively thin lead aprons and light weight, portable shields. To investigate the feasibility of 241Am sources for intracavitary irradiation, dosimetry studies on prototype 241Am sources have been performed and a computer model for the determination of dose distributions around encapsulated cylindrical sources of 241Am has been developed and tested. Results of dosimetry measurements using ionization chambers, lithium fluoride thermoluminescent dosimeters, a scanning scintillation probe, and film dosimetry, confirm theoretical predictions that these sources can deliver dose rates adequate for intracavitary irradiation. Further dosimetry measurements in simulated clinical situations using lead foils and test tubes filled with hypaque or barium sulfate, confirm the predicted effectiveness of in vivo shielding which can be readily achieved with 241Am sources.

Americium↗
PubMed1990

Performance of a prototype fluoroscopic radiotherapy imaging system.

An increasing demand exists for the implementation of radiotherapy imaging during routine patient treatment, not only for quality assurance of field alignment, but also to obtain full documentation of the actual radiation treatments given. As the method using conventional portal films has distinct disadvantages, alternative methods are required which preferably are faster and produce images of better quality. This paper describes the performance of a prototype fluoroscopic system in terms of spatial resolution and contrast resolution as well as imaging of patients during routine treatments. The system described appears to be suitable for patient set-up and treatment verification and documentation.

Equipment Design↗
PubMed1995

Performance evaluation of a prototype high resolution digital radiographic/near real-time fluoroscopic computerized tomographic system for radiotherapy simulation.

PURPOSE: A new prototype digital radiographic/near real-time fluoroscopic and computerized tomographic (CT) imaging system has been developed and its performance is evaluated for future implementation in a radiotherapy simulator. METHODS AND MATERIALS: The new imaging modality uses a slow scan cooled charge-coupled device (CCD) camera with 2 k x 2 k x 12 bit image resolution. X-ray images formed by a Gd2O2S:Tb flat screen are directly viewed by the CCD camera via a 45 degrees angled mirror and a high speed objective lens. For CT image reconstruction, digital data from a slit image on the CCD array obtained from time-controlled x-ray scans around the object are transferred to a second tomographic computer for processing and display. RESULTS: In the digital radiographic mode, and for a 43.2 x 43.2 cm field size at the phosphor plane, the spatial resolution of the system is 2.3 +/- 0.1 lp/mm (1 sigma) as measured at the 4% level of the modulation transfer function (MTF), whereas the contrast resolution has a value of 0.5%. In the fluoroscopic mode, the system may be operated at a maximum rate of eight frames/s at a relatively lower spatial and contrast resolution. For CT scans, although the potential intrinsic spatial resolution at the isocenter is 0.35 mm, display-limited spatial resolutions of 1.2 and 1.6 mm were obtained for 30 and 40 cm reconstruction circle diameters, respectively. A contrast resolution of 1% at 0.015 Gy entrance dose was achieved, and CT reconstruction circles of up to 51 cm were attainable. CONCLUSION: The new CCD-based imaging system is capable of delivering high-quality digital radiographic and CT images for radiotherapy simulation, whereas the near real-time fluoroscopic mode yields acceptable flicker-free lower quality images at object speeds typical of simulation motions.

Fluoroscopy↗
PubMed1989

Molecular analysis of one of multiple protease-encoding genes from the prototype virulent strain of Bacteroides nodosus.

The aim of these studies was to examine the organization of the Bacteroides nodosus protease-encoding gene(s). The extracellular serine proteases (38 kDa) from the prototype virulent strain of B. nodosus were purified and used to raise a specific antiserum in rabbits. This antiserum was used in a colony immunoassay to screen a genomic DNA library constructed in Escherichia coli using BamHI-digested B. nodosus DNA and the plasmid pBR322. An E. coli clone expressing a 50-kDa immunoreactive polypeptide was identified. No protease activity was detected in the culture media, or in crude soluble and membrane fractions prepared from this clone. Restriction mapping and deletion analysis of the recombinant plasmid, pEKM2, was used to locate the coding region to a 1.4-kb EcoRI-BamHI fragment which was subsequently sequenced. A large open reading frame was found to extend through the BamHI site from a putative start codon just downstream from the EcoRI site, which indicated that the complete gene was not isolated. Southern blotting demonstrated that there were at least three B. nodosus BamHI fragments which were homologous to the 0.4-kb PstI-BamHI fragment of pEKM2. Based on these results the existence of multiple protease genes in B. nodosus was postulated.

Amino Acid Sequence↗