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Biomedical subjects

M Knight

Publications and source records attributed to M Knight.

At least 55 records · Page 3Linked to original sources
PubMed1996

Use of RAPD-PCR to differentiate genetically defined lines of an intermediate host of Schistosoma mansoni, Biomphalaria glabrata.

The genetic differentiation among several laboratory-maintained pedigree snail lines of Biomphalaria glabrata (with different susceptibility phenotypes to Schistosoma mansoni infection) was assessed with the random amplified polymorphic DNA method. Out of the 20 primers tested, 2 (OPA-01 and OPA-06) gave reproducible markers with either individual or bulked DNA samples from resistant (BS-90, 10-R2, LAC-line) and susceptible (M-line) snails. Arbitrary primer, OPA-01, amplification of BS-90 DNA identified a 180-bp strain-specific fragment and a 400-bp marker in the susceptible M-line stock. In the 10-R2 and LAC snail lines, OPA-01 specific markers of 200 bp and 550 bp were identified. Amplification with primer OPA-06 identified several major strain-specific markers in the BS-90 (150 bp, 400 bp, 800 bp) and M-line (1,100 bp) snails. The heritability of the RAPD markers was evaluated in progeny snails derived from a cross between the BS-90 and M-line stocks. Results showed that markers were inherited in a dominant or codominant fashion. The 1,100-bp M-line marker was inherited in all susceptible progeny snails analyzed.

Animals↗
PubMed1995

Standardization of absolute CD4+ lymphocyte counts across laboratories: an evaluation of the Ortho CytoronAbsolute flow cytometry system on normal donors.

The Ortho CytoronAbsolute is a flow cytometer designed to provide direct absolute counts of lymphocytes and their subsets from a single instrument. This study was designed to determine the performance of four geographically separated CytoronAbsolute instruments using 24-h-old, shipped, whole blood samples and to compare the results obtained on the CytoronAbsolute to those obtained using combinations of hematology instruments and other flow cytometers. The absolute count feature of the CytoronAbsolutes located at the four sites were cross calibrated and gave across-site coefficients of variation (CVs) of <4.0% for absolute count and 8.2% for absolute lymphocyte count. The calibration was stable for at least 2 months. Absolute lymphocyte counts and lymphocyte percentage immunophenotypes were determined on blood from 50 healthy human immunodeficiency virus (HIV)-seronegative donors. There were no significant site-to-site differences (each P > .05) in CD3+/CD4+ absolute lymphocyte counts determined on the CytoronAbsolute. In contrast, there was a significant site-to-site difference (P < .001) between sites 2 and 3 and sites 3 and 4 in the absolute CD3+/CD4+ lymphocyte counts determined via the conventional method of combining a flow cytometry-derived percentage with a hematology instrument-derived lymphocyte count. There was no significant difference (P = .388) in CD3+/CD4+ lymphocyte percent determinations between the CytoronAbsolute and the FACScan or Profile II flow cytometers used in this study. These results demonstrate that different operators can cross calibrate CytoronAbsolutes for absolute CD3+/CD4+ lymphocyte subset determinations, even over large geographic distances.

CD4 Lymphocyte Count↗
PubMed1995

Separation and purification of peptides by high-speed counter-current chromatography.

Preparative separations of peptides have been accomplished using high-speed counter-current chromatography. This has been made possible by the use of a particular solvent system that does not exhibit solvent carryover at high speed flow and centrifugation conditions. The solvent system composed of tert.-butyl methyl ether, n-butanol, acetonitrile and aqueous trifluoroacetic acid which can be adjusted in volume ratios and percent acid is employed in two instruments for counter-current chromatography. The cross-axis coil planet centrifuge was used for separation of various dipeptides. Superior resolution was obtained with the multi-layer coil planet centrifuge in the separation of six dipeptides and in the preparative purification of two synthetic peptides.

Amino Acid Sequence↗
PubMed1995

Effects of mechanical signaling on plant cell cytosolic calcium.

Mechanical signals are important influences on the development and morphology of higher plants. Using tobacco transformed with the Ca(2+)-sensitive luminescent protein aequorin, we recently reported the effects of mechanical signals of touch and wind on the luminescence and thus intracellular calcium of young seedlings. When mesophyll protoplasts are isolated from these transgenic tobacco plants and mechanically stimulated by swirling them in solution, cytoplasmic Ca2+ increases immediately and transiently up to 10 microM, and these transients are unaffected by an excess of EGTA in the medium. The size of the transient effect is related to the strength of swirling. Epidermal strips isolated from transgenic tobacco leaves and containing only viable guard cells and trichomes also respond to the strength of swirling in solution and can increase their cytoplasmic Ca2+ transiently up to 10 microM. Finally, the moss Physcomitrella patens containing recombinant aequorin exhibits transient increases in cytoplasmic Ca2+ up to 5 microM when swirled in solution. This effect is strongly inhibited by ruthenium red. Our data indicate that the effect of mechanical stimulation can be found in a number of different cell types and in a lower plant as well as tobacco and suggest that mechanoperception and the resulting increase in cytoplasmic Ca2+ may be widespread.

Aequorin↗
PubMed1995

The effect of nitrogen dioxide exposure on the release of surfactant isolated from neonatal rabbit type II pneumocytes in culture.

Nitrogen dioxide (NO2) is a well-known environmental air toxin, produced from a variety of sources, including cigarette smoke. Because of the growing knowledge of the harmful effects of passive smoking on children, we decided to study the effect of NO2 exposure on the release of surfactant from isolated neonatal type II pulmonary epithelial cells. After isolation from 1 to 4 day old rabbits, type II epithelial cells were allowed to adhere for 18 hours, washed, media changed, and were exposed to either 5% CO2 in room air or NO2, 5 ppm, for 2 hours (all results mean +/- sd; comparisons, paired t-test). There was no difference in cell number or viability prior to exposure. Cells exposed to NO2 had an increase in LDH release [LDH activity in media/(LDH in media+cells) x 100], air 12.6 +/- 2.2%, NO2 21.7 +/- 3.7%, (p < 0.05). NO2-exposed cells also had an increase in total phospholipid (microgram/cell culture dish) in media compared to air exposed, air 170.13 +/- 7.54, NO2 195.15 +/- 11.2, (p < 0.05). 3H-choline incorporation as a precursor to disaturated phosphatidylcholine (DSPC) was also conducted during exposure to either air or NO2. Incorporation of 3H-choline into surfactant lipid was increased in media from cells after NO2 exposure compared to air, 58.23 +/- 15.16 air, 76.81 +/- 19.86 NO2 (cpm/microgram protein; p < 0.05). These results show that 2 hours of 5 ppm NO2 exposure is associated with an increase in release of surfactant from neonatal type II cells in culture.

Animals↗
PubMed1995

An investigation of methods for enriching trophoblast from maternal blood.

Trophoblast deportation is known to occur in normal human pregnancy, but it is not yet clear whether these cells routinely enter the maternal peripheral circulation and are available as a source of fetal DNA for non-invasive prenatal diagnosis of genetic disorders. To resolve this issue requires an efficient method of enriching trophoblast from maternal blood combined with a means to confirm its identity. Five different techniques were tested on ten retroplacental blood samples to determine the most sensitive and operator-efficient method. Lysis of red cells alone gave the best recovery of trophoblast but had to be discounted, together with Ficoll density gradient centrifugation, due to the very low purity and the excessive time required. Fluorescence-activated cell sorting (FACS) of pre-enriched trophoblast resulted in the lowest recovery rate (8 per cent) despite a 3250-fold enrichment and a very high purity. Immunomagnetic beads (Dynabeads) coated with anti-CD16 antibody proved to be the best method for the subsequent immunocytochemical characterization of deported trophoblast. However, IO beads coated with anti-CD45 antibody may be more useful for isolating trophoblast for prenatal diagnosis due to the high purity, enrichment (32-fold), and recovery rate (78 per cent) obtained with this method.

Cell Count↗
PubMed1995

Inhibitory cyclic analogues and chlorambucil derivatives of bombesin-like peptides.

Analogues of the amphibian neuropeptide, bombesin, and of the mammalian homologue, gastrin-releasing peptide, have been synthesized and their biological activity studied in small cell lung carcinoma and rat pancreatic acinar cells. The compounds are truncated sequences of the active tetradecapeptide BN(1-14) or GRP(20-27). Peptides were cyclized between position 5 or 7 and the carboxyl end of the des-Met14 fragment with D and L Ala11 and Lys5 substitutions, as well as various N-terminal groups attached. The smallest cyclic peptide, BN(7-13), bound to SCLC membranes with microM potency and inhibited BN stimulation of intracellular Ca++ levels. The most potent inhibitor is N-chloroambucil-[His7,D-Ala11]BN(7-13)ethyl ester, which antagonized BN function in SCLC and acinar cells with nM potency and also inhibited clonal growth of carcinoma cell lines.

Amino Acid Sequence↗
PubMed1995

Constant observation: implications for nursing practice.

1. Constant observation is an increased level of observation and supervision in which continuous one-to-one monitoring techniques are utilized to assure the safety and well-being of an individual patient or others in the patient care environment. 2. Individuals who provide constant observation vary widely among health care facilities; but ultimately are the responsibility of the registered nurse. There are many areas that must be addressed by institutions when considering the use or implementation of constant observation. These include: measuring the associated costs, risk management, role development, orientation of employees, and performance evaluation. 3. The changing health care environment and public concern over the quality of health care and risk management require nursing administrators to consider risk-benefit and cost-benefit analyses related to constant observation. There is continued need for protocol and policy development, as well as for guidelines and orientation of staff regarding constant observation.

Cost-Benefit Analysis↗
PubMed1995

Schistosoma mansoni: changes in the albumen gland of Biomphalaria glabrata snails selected for nonsusceptibility to the parasite.

The LAC-line strain of the snail Biomphalaria glabrata has very low susceptibility to the parasite Schistosoma mansoni and a very low reproductive potential. Upon examination of the reproductive tract of these snails, light and electron microscopy revealed obvious abnormalities in the albumen gland. Secretory cells that are normally cuboidal in susceptible NMRI (F0) snails were squamous in LAC-line snails. These LAC-line cells contained small secretory granules and negligible rough endoplasmic reticulum and Golgi, compared to large granules and an extensive array of both organelles in F0 albumen gland cells. Comparative analyses of soluble protein extracts of F0 and LAC-line albumen glands showed several qualitative differences. Among the most prominent was an 18-kDa protein in F0 snails that was remarkably reduced in the soluble protein extracts of LAC-line snails. Also, metabolic incorporation of [35S]-methionine was impaired in LAC-line albumen glands. Whether these albumen gland changes are caused by decreased susceptibility to parasitism is yet to determined.

Animals↗
PubMed1994

Adverse drug reactions in neonates.

Adverse drug reactions (ADR) are uncommon causes of admission of neonates to the neonatal intensive care unit. The neonate, however, is potentially at significant risk for adverse drug reactions because of underdeveloped mechanisms and systems for handling drugs (the Gray Baby Syndrome with chloramphenicol as a classic example), the fact that infants in neonatal intensive care units are often critically ill with multiple organ system dysfunction, that they may be on multiple drugs, and that they may present with an adverse drug reaction as a result of exposure while still a fetus. There is also a history of misadventures in the neonatal intensive care unit and newborn nurseries due to exposure to antibacterial agents that produced systemic effects from percutaneous absorption. In this review, an overview of the mechanisms of adverse drug reactions will be presented, followed by a general review of the experience of adverse drug reactions in neonates and some specific examples of current adverse drug reactions and a suggested approach for the prevention and evaluation of adverse drug reactions in neonates.

Critical Illness↗
PubMed1994

Mechanical signalling, calcium and plant form.

Calcium is a dynamic signalling molecule which acts to transduce numerous signals in plant tissues. The basis of calcium signalling is outlined and the necessity for measuring and imaging of calcium indicated. Using plants genetically transformed with a cDNA for the calcium-sensitive luminescent protein, aequorin, we have shown touch and wind signals to immediately increase cytosol calcium. Touch and wind signal plant cells mechanically, through tension and compression of appropriate cells. Many plant tissues and cells are very sensitive to mechanical stimulation and the obvious examples of climbing plants, insectivorous species as well as other less well-known examples are described. Touch sensing in these plants may be a simple evolutionary modification of sensitive mechanosensing system present in every plant. The possibility that gravitropism may be a specific adaptation of touch sensing is discussed. There is a growing appreciation that plant form may have a mechanical basis. A simple mechanical mechanism specifying spherical, cylindrical and flat-bladed structures is suggested. The limited morphological variety of plant tissues may also reflect mechanical specification. The article concludes with a discussion of the mechanisms of mechanical sensing, identifying integrin-like molecules as one important component, and considers the specific role of calcium.

Aequorin↗
PubMed1994

Self-staffing: improving care and staff satisfaction.

A self-staffing system on an infant/toddler unit with widely fluctuating census has resulted in increased staff autonomy, schedule flexibility and nurse satisfaction. Staff agree unanimously that quality of care has improved greatly. In addition, early indications show the potential for significant cost savings.

Humans↗
PubMed1993

Schistosoma mansoni: analysis of an unusual infection phenotype in the intermediate host snail Biomphalaria glabrata.

Snails from a B. glabrata stock, selected for nonsusceptibility to the NMRI strain of S. mansoni, exhibited unusual schistosome infections, with multiple sporocysts prominent in the head-foot (foot-sporocysts). When F1 progeny from numerous crosses between well-defined susceptible (S) and resistant (R) parental snails were exposed, 60% of the infected snails also exhibited this unusual phenotype. F1 progeny from S x S snail crosses developed normal infections. Foot-sporocysts usually developed much later than secondary sporocysts of normal infections and before 12 weeks postexposure the tissue reaction surrounding foot-sporocysts was less intense than reactions to sporocysts in other tissues of the body. Cercariae were seen emerging directly from foot-sporocysts. Infection of S x R hybrid progeny by three other strains of S. mansoni also resulted in the production of foot-sporocysts. Development of the foot-sporocyst infection phenotype in progeny from many snail crosses suggests that this phenotype is more common than previously recognized. Over 50% of the F1 progeny from S x R parental crosses developed patent infections, a fact relevant to the possible biological control of schistosomiasis by the introduction of refractory snails into endemic areas.

Animals↗
PubMed1992

Identification of a repetitive element in the snail Biomphalaria glabrata: relationship to the reverse transcriptase-encoding sequence in LINE-1 transposons.

BamHI-digested Biomphalaria glabrata DNA contains a repetitive 2.0-kb fragment which is readily discernible by ethidium bromide staining. We present evidence that this repetitive element is related at both the nucleotide and amino acid levels to long interspersed nuclear element (LINE)-like transposons. Although comparable elements have been described in several invertebrates, this is the first report of a molluscan homologue. In common with LINE transposons, an open reading frame in the B. glabrata element shows significant homology to reverse transcriptase--a feature believed to allow the dissemination of these elements in the eukaryotic genome.

Amino Acid Sequence↗
PubMed1992

Behavioural studies on WAY100289, a novel 5-HT3 receptor antagonist, in two animal models of anxiety.

The novel 5-HT3 receptor antagonist, WAY100289, was examined in two animal models of anxiety: the mouse two-compartment light: dark box, and the rat potentiated acoustic startle paradigm. The activity of WAY100289 in the light: dark box model was also compared with that of the selective 5-HT3 receptor antagonists ondansetron, zacopride, ICS-205,930 and quaternary ICS-205,930 (QICS). WAY100289 mimicked the activity profile of benzodiazepine positive controls in the mouse light: dark box, i.e. WAY100289 markedly and significantly increased the exploratory activity of mice in the more aversive light compartment, at doses of 0.01-1.0 mg/kg s.c. and 0.1-10.0 mg/kg p.o. Zacopride and ondansetron induced comparable effects at doses of 0.001-1.0 mg/kg s.c. ICS-205,930 displayed a markedly biphasic dose-response relationship; being active at 0.01 mg/kg s.c., but not at higher or lower doses. QICS was not active in the light: dark box up to a dose of 10 mg/kg s.c., suggesting that the compound does not enter the brain readily. WAY100289 was also active in the rat potentiated acoustic startle model, significantly attenuating the potentiated startle response at doses of 0.03 and 0.3 mg/kg s.c. The activity profile of WAY100289 in this model resembled that of ondansetron. These data strongly suggest that WAY100289 may possess anxiolytic properties in the clinic.

Analysis of Variance↗