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M Edwards

Publications and source records attributed to M Edwards.

At least 55 records · Page 3Linked to original sources
PubMed1987

Expert systems: frames, rules or logic for species identification?

The role of expert systems in species identification, with particular reference to the problems posed by damaged specimens and inexperienced taxonomists, is discussed. Of the three main types of expert systems available, the frame-based system is shown to provide the most appropriate model for a taxonomic expert system rather than a logic- or rule-based system. The advantages of an expert system over other computer-aided methods of identification are considered. A rule-based system requires the original knowledge (species descriptions) to be structured into rules, whereas a frame-based system can store the generic and specific descriptions in a series of frames. The frames fall into a hierarchy which closely resembles the taxonomic hierarchy, and down which information can be inherited. Two aspects of frame-based systems considered are the use of probabilities in identification, and the optimum structure of the knowledge base. The conventional use of probabilities is to provide an indication of the correctness of the result. However, in some studies involving the identification of many specimens, the speed of identification may be increased (with a reduction in accuracy) if identifications are made to a predetermined probability level. Although frames allow accurate representation of the taxonomic hierarchy, a semantic net, incorporating structures of the organism and/or details of the habitat may result in a more efficient expert system.

Animals↗
PubMed1987

Risk factors for atherothrombotic brain infarction in persons over 62 years of age in a long-term health care facility.

A history of systolic (greater than or equal to 160 mm Hg) or diastolic (greater than or equal to 90 mm Hg) hypertension, diabetes mellitus (fasting venous plasma glucose greater than or equal to 140 mg/dl), a history of cigarette smoking, fasting serum total cholesterol greater than or equal to 200 mg/dl and greater than or equal to 250 mg/dl, and obesity (greater than or equal to 20% above ideal body weight) were examined as risk factors for atherothrombotic brain infarction (ABI) in 144 men, mean age 81 +/- 8 years, and 391 women, mean age 82 +/- 8 years, in a long-term health care facility. ABI occurred in 33 of 144 men (23%) and in 68 of 391 women (17%), P not significant. A history of systolic or diastolic hypertension correlated with ABI in both men and women (P less than 0.001). Diabetes mellitus correlated with ABI in both men and women (P less than 0.001). A history of cigarette smoking correlated with ABI in men (P less than 0.02) but not in women. Serum total cholesterol greater than or equal to 200 mg/dl and greater than or equal to 250 mg/dl did not significantly correlate with ABI in men or in women. Obesity did not significantly correlate with ABI in men or in women. Systolic or diastolic hypertension, diabetes mellitus, and cigarette smoking are risk factors for ABI in elderly men. Systolic or diastolic hypertension and diabetes mellitus are risk factors for ABI in elderly women.

Aged↗
PubMed1986

Purification and properties of a novel xyloglucan-specific endo-(1----4)-beta-D-glucanase from germinated nasturtium seeds (Tropaeolum majus L.).

Endo-(1----4)-beta-D-glucanase activity has previously been detected in the cotyledons of germinated nasturtium (Tropaeolum majus L.) seeds, and has been linked to the hydrolysis in vivo of storage xyloglucan (amyloid) (Edwards, M., Dea, I. C. M., Bulpin, P. V., and Reid, J. S. G. (1985) Planta (Berl.) 163, 133-140). Extracts from the cotyledons of 14-day seedlings are now shown to contain a single endo-glucanase activity, and it has been purified to apparent homogeneity by sequential anion-exchange chromatography, cation-exchange chromatography, and gel filtration. The purified enzyme gave a single protein band on polyacrylamide gel electrophoresis, dodecyl sulfate gel electrophoresis, and isoelectric focusing. The isoelectric point was 5.0, the pH optimum 4.5-5.0, and the temperature optimum 40 degrees C. Dodecyl sulfate electrophoresis gave a molecular weight of 29,000; permeation methods gave lower values. The enzyme contained about 5% carbohydrate. An endo mode of action on tamarind seed xyloglucan was deduced by monitoring solution viscosity and reducing power, and by analyzing the end products of the reaction. The specificity of the enzyme toward a wide range of substrates, including celluloses, carboxymethyl and hydroxyethyl celluloses, glucomannan, galactoglucomannans, mixed-linkage (1----3 and 1----4)-beta-D-glucan, laminarin, and xyloglucans from seeds and primary cell walls, was tested. Only the xyloglucans were hydrolyzed. It is concluded that the enzyme is a pure, endo-acting (1----4)-beta-D-glucanase which is novel in its apparently complete specificity toward xyloglucans. It is speculated that enzymes of this type may have escaped earlier detection because it is normal practice to screen for endo-(1----4)-beta-D-glucanase using artificial cellulose derivatives and that they may be widely involved in xyloglucan metabolism in plant cell walls.

Cellulase↗
PubMed1986

Risk factors for coronary artery disease in persons older than 62 years in a long-term health care facility.

A history of smoking 5 to 60 cigarettes per day, hypercholesterolemia (fasting total serum cholesterol 200 mg/dl or more), history of systolic (160 mm Hg or more) or diastolic (90 mm Hg or more) hypertension, diabetes mellitus (fasting venous plasma glucose 140 mg/dl or more) and obesity (at least 20% above ideal body weight) were correlated with coronary artery disease (CAD) in 138 men (mean age 82 +/- 8 years) and 380 women (mean age 82 +/- 8 years) in a long-term health care facility. CAD occurred in 43 of 138 men (31%) and in 103 of 380 women (27%), difference not significant. A history of smoking 5 to 60 cigarettes per day significantly correlated with CAD in men (p less than 0.001) but not in women. Hypercholesterolemia significantly correlated with CAD in both men (p less than 0.001) and women (p less than 0.005). A history of systemic hypertension significantly correlated with CAD in women (p less than 0.001) but not in men. Diabetes mellitus did not significantly correlate with CAD in men or women but weakly correlated with CAD in men plus women (p less than 0.05). Obesity did not significantly correlate with CAD in men or women. Hypercholesterolemia, a history of smoking 5 to 60 cigarettes per day, and a history of systemic hypertension were considered major risk factors. Having 2 or 3 major risk factors correlated with CAD significantly better than having no or 1 major risk factor in both elderly men (p less than 0.001, p less than 0.01) and women (p less than 0.001).

Aged↗
PubMed1986

Inhibitory effect of substituted aromatic hydrocarbons on adherence of Escherichia coli to human epithelial cells.

Adherence of Escherichia coli to epithelial cells is postulated to be a necessary step in the pathogenesis of urinary tract infections. Investigations have focused on the role of carbohydrates in adherence because of the ability of mannose to inhibit adherence; however, there have been several reports of an additional hydrophobic receptor. Here we describe the inhibition of adherence mediated by substituted aromatic hydrocarbon compounds and the relationship of our findings to support the role of a postulated hydrophobic-binding domain.

Adhesiveness↗
PubMed1986

MRI of angiographically occult vascular malformations.

Eleven patients with 15 angiographically occult arteriovenous malformations were studied by magnetic resonance (MR) imaging and computed tomography (CT). Five patients had biopsy proof; six were clinically diagnosed from the long-term clinical follow-up (more than 3 years) and imaging features. Of the 15 lesions, 11 were recognized by both CT and MR. Each method was falsely negative for two lesions. The most useful contribution of MR in the characterization of angiographically occult arteriovenous malformations was the depiction of hemorrhagic foci in 12 of 13 lesions seen on MR. High-attenuation foci indicative of hematomas were seen in only five lesions on CT; the rest were iso- or hypoattenuating. CT detected two very small lesions, in one case as punctate foci of enhancement and in the other as punctate calcification, that were not seen with MR. MR complements CT in characterizing angiographically occult arteriovenous malformations and in distinguishing them from similar-appearing lesions, in particular, small neoplasms. However, when such lesions are seen with only focal calcification and subtle enhancement on CT, routine MR may miss them.

Adolescent↗
PubMed1986

Distribution of stage-specific neurite-associated proteins in the developing murine nervous system recognized by a monoclonal antibody.

A monoclonal antibody, 4D7, obtained with embryonic rat brain as an immunogen, recognizes an epitope on 3 protein species of 150-160, 100-110, and 80 kDa, present in mouse and rat brain during the fetal period. Vital immunostaining of dissociated cultures of fetal forebrain indicates that the antigen is localized largely on the external plasma membrane of a subpopulation of neurites. Immunocytochemistry reveals that the distribution of the antigen in vivo is restricted to the nervous system. Immunoreactivity is concentrated primarily in the pathways of a limited set of CNS and PNS axon systems during early stages of their development, as delineated by staining with the neurofilament antibody, C2. Depending on the particular axon system, immunoreactivity with 4D7 persists only for one to several days of prenatal or perinatal development. In the spinal cord, stage-specific-neurite-associated proteins (SNAP) expression occurs first along motor axon pathways on embryonic day (E) 10 and then within the nerve trunks of dorsal root ganglia and the commissural fiber system on E11. Immunoreactivity is detectable among most cranial nerves starting in the interval from E11 to E13. Within the brain, the onset of SNAP expression within several discrete axon tracts occurs in the interval E14-16, including the lateral olfactory tract, anterior commissure, corpus callosum, fasciculus retroflexus, and fornix. Immunoreactivity within the embryonic intermediate zones of some structures matches the location of certain other axon systems. Sites of 4D7 staining which do not correspond to the location of axon populations include the internal portion of the external granular layer of the postnatal cerebellum and the cortex of the reeler mutant mouse. The predominant localization of the 4D7 antigen among axon systems and its precisely regulated spatio-temporal pattern of expression are consistent with the possibility that the SNAP antigens play a significant role in the early stages of growth of axonal tracts in vivo.

Animals↗
PubMed1985

A Trojan Horse mechanism for the spread of visna virus in monocytes.

Visna virus is the prototype of the lentivirus subfamily of retroviruses that cause slow infections of sheep and goats. These viruses persist and can be isolated from blood and cerebrospinal fluid for years despite neutralizing antibody. In the studies reported here we have used quantitative in situ hybridization to analyze infected leukocytes. We show that (1) monocytes harbor the visna genome; and (2) virus gene expression is as constrained in this cell as it is in glial and epithelial cells. These results are in accord with a Trojan Horse mechanism of virus dissemination in an immunologically responsive host.

Animals↗