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Biomedical subjects

E Bell

Publications and source records attributed to E Bell.

At least 19 recordsLinked to original sources
PubMed1992

Tissue characterization and assessment of preoperative chemotherapeutic response in musculoskeletal tumors by in vivo 31P magnetic resonance spectroscopy.

This study investigates the potential of in vivo 31P magnetic resonance spectroscopy (MRS) to characterize musculoskeletal tumors and to determine preoperative levels of histological necrosis, which is an important clinical indicator of patient response. Pretherapy MRS was performed on 28 patients with large musculoskeletal tumors: 13 with osteosarcoma, 3 with chondrosarcoma, 5 with malignant fibrous histiocytoma, 1 with desmoid tumor, 1 with Ewing's, 2 with hemangioendothelioma, 1 with myxoid liposarcoma, 1 with synovial cell sarcoma, and 1 with rhabdomyosarcoma. Fifteen patients had follow-up MRS examinations after commencement of chemotherapy (mean of five/patient), eight of whom have now had surgery. Elevated levels of PMEs (P < 0.01), P(i) (P < 0.01), and PDEs (P < 0.02) as well as elevated tumor pH (P < 0.05) were observed in all patients. The synovial cell sarcoma was characterized by high levels of PMEs (> 20%) and low pH (pH 6.76). This contrasted with the spectra obtained from the malignant fibrous histiocytomas which had high levels of PDEs (17 +/- 5%). Reductions in PDE levels postchemotherapy were associated with a high degree of necrosis (> 90%) at surgery, while an increase in PDE levels was associated with a low level of histological necrosis. Likewise, reductions in the ratios PDE/NTP and PDE/PCr and an increase in P(i)/PDE were also associated with a high level of necrosis.

Adult↗
PubMed1992

Glucose metabolism and hypoglycaemia in SIDS.

Once a child is born its survival depends on the maturation of the blood glucose homeostatic control mechanisms. When this fails or where there is an inborn error of metabolism the infant is susceptible to potentially fatal hypoglycaemic episodes. A variety of environmental stresses, either singly or in combination, such as inappropriate or low caloric intake, acute infections of childhood, endotoxaemia, fever, xenobiotic exposure, oxidative stress or anaphylaxis, can greatly exacerbate the deficiency of the normal homeostatic compensatory mechanism and result in the onset of hypoglycaemia. Various inborn errors have been found in infants who died of SIDS. Our approach to this problem has been to use the six microsomal glucose-6-phosphatase proteins as a model system to study defects in carbohydrate metabolism in cases of SIDS. Initial studies determined the ontogeny of the glucose-6-phosphatase proteins and showed that intact microsomes isolated from unfrozen liver samples can be used to study glucose-6-phosphatase in cases of SIDS that were presumably due to the low concentrations of liver lipid peroxidation. More recently we have used a combination of techniques to demonstrate the abnormalities of glucose-6-phosphatase in cases of SIDS. Classic gross pathology and histology have now clearly defined the various subgroups of sudden and unexpected deaths of infancy. This now enables us to develop new molecular approaches to predict and prevent hypoglycaemia in infants who are at risk of SIDS.

Blood Glucose↗
PubMed1991

The partial amino acid sequence of the NAD(+)-dependent glutamate dehydrogenase of Clostridium symbiosum: implications for the evolution and structural basis of coenzyme specificity.

The amino acid sequence is reported for CNBr and tryptic peptide fragments of the NAD(+)-dependent glutamate dehydrogenase of Clostridium symbiosum. Together with the N-terminal sequence, these make up about 75% of the total sequence. The sequence shows extensive similarity with that of the NADP(+)-dependent glutamate dehydrogenase of Escherichia coli (52% identical residues out of the 332 compared) allowing confident placing of the peptide fragments within the overall sequence. This demonstrated sequence similarity with the E. coli enzyme, despite different coenzyme specificity, is much greater than the similarity (31% identities) between the GDH's of C. symbiosum and Peptostreptococcus asaccharolyticus, both NAD(+)-linked. The evolutionary implications are discussed. In the 'fingerprint' region of the nucleotide binding fold the sequence Gly X Gly X X Ala is found, rather than Gly X Gly X X Gly. The sequence found here has previously been associated with NADP+ specificity and its finding in a strictly NAD(+)-dependent enzyme requires closer examination of the function of this structural motif.

Amino Acid Sequence↗
PubMed1991

Epidermis generated in vitro: practical considerations and applications.

The technology for culture of epidermis is one of the most advanced to date for generation of a tissue in vitro. Cultured epidermis is already used for a number of applications ranging from use as a permanent skin replacement to use as an organotypic culture model for toxicity testing and basic research. While simple epidermal sheets have been grafted successfully, more advanced models for skin replacement consisting of both dermal and epidermal components are in development and being tested in a number of laboratories. One of the most advanced in vitro models is the living skin equivalent, an organotypic model consisting of a collagen lattice contracted and nourished by dermal fibroblasts overlaid with a fully formed epidermis.

Culture Techniques↗
PubMed1991

Lipoxygenase gene expression is modulated in plants by water deficit, wounding, and methyl jasmonate.

Two classes of lipoxygenase (LOX) cDNAs, designated loxA and loxB, were isolated from soybean. A third lipoxygenase cDNA, loxP1, was isolated from pea. The deduced amino acid sequences of loxA and loxB show 61-74% identity with those of soybean seed LOXs. loxA and loxB mRNAs are abundant in roots and non-growing regions of seedling hypocotyls. Lower levels of these mRNAs are found in hypocotyl growing regions. Exposure of soybean seedlings to water deficit causes a rapid increase in loxA and loxB mRNAs in the elongating hypocotyl region. Similarly, loxP1 mRNA levels increase rapidly when pea plants are wilted. loxA and loxB mRNA levels also increase in wounded soybean leaves, and these mRNAs accumulate in soybean suspension cultures treated with 20 microM methyl jasmonate. These results demonstrate that LOX gene expression is modulated in response to water deficit and wounding and suggest a role for lipoxygenase in plant responses to these stresses.

Acetates↗
PubMed1991

Recipes for reconstituting skin.

Reconstituted Living Skin Equivalent (LSE) is made up of a dermal equivalent (DE) on which keratinocytes are plated where they give rise to a multilayered differentiated epidermis. The dermal equivalent develops through interactions between fibroblasts and collagen fibrils that begin to form after the cell-matrix precursor is cast. The gel that forms as a result of collagen polymerization and fluid trapping is contracted uniformly in all dimensions. By securing it at ends and edges in the mold in which it is cast, the final dimensions, strength and morphology of the forming tissue are altered. The same phenomena are seen in casting tubular tissues for the fabrication of small caliber blood vessel equivalents. The cells of the dermal equivalent are biosynthetically active and enrich the matrix to different degrees with secretory products, depending on how the cells are stimulated and on the presence or absence of an epidermis. Collagen biosynthesis by dermal cells in the DE is sensitive to growth factors, ascorbate concentrations and amino acid pools. Both ascorbate and TGF beta 1 increase total collagen biosynthesis at least two-fold by one week after tissue formation. With TGF beta 1 present, the capacity of cells in the DE to synthesize collagen increases with time, over a two-week period. If ascorbate (200 micrograms/ml) is added just after the tissue is cast and daily thereafter, contraction lattice is blocked, and collagen biosynthesis is enhanced relative to contracted controls that had received 200 micrograms/ml ascorbate once. The increase was nearly an order of magnitude over that of controls and was coordinate with a comparable increase in hyaluronate and sulfated glycosaminoglycan (GAG) production as shown by TCA-precipitable glucosamine in the intercellular matrix of the DE. Both the LSE and the Living Dermal Equivalent (LDE) exhibit complex responses to UV radiation and to various chemicals that are greatly different from responses given by monolayered cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1990

Analysis of a cDNA encoding arginine decarboxylase from oat reveals similarity to the Escherichia coli arginine decarboxylase and evidence of protein processing.

Arginine decarboxylase is the first enzyme in one of the two pathways of putrescine synthesis in plants. We purified arginine decarboxylase from oat leaves, obtained N-terminal amino acid sequence, and then used this information to isolate a cDNA encoding oat arginine decarboxylase. Comparison of the derived amino acid sequence with that of the arginine decarboxylase gene from Escherichia coli reveals several regions of sequence similarity which may play a role in enzyme function. The open reading frame (ORF) in the oat cDNA encodes a 66 kDa protein, but the arginine decarboxylase polypeptide that we purified has an apparent molecular weight of 24 kDa and is encoded in the carboxyl-terminal region of the ORF. A portion of the cDNA encoding this region was expressed in E. coli, and a polyclonal antibody was developed against the expressed polypeptide. The antibody detects 34 kDa and 24 kDa polypeptides on Western blots of oat leaf samples. Maturation of arginine decarboxylase in oats appears to include processing of a precursor protein.

Amino Acid Sequence↗
PubMed1988

A short exercise and living course for asthmatics.

A 5-day, non-residential exercise and living course for children with asthma is described as a feature of a programme of outpatient physiotherapy. Eleven children undertaking such a course were compared with 10 asthmatic children in a control group. The subject group showed, in the short term at least, an improvement in bronchial lability, peak flow rates, nocturnal and daytime wheeze, and activity compared with the controls. These findings were statistically significant. There was no difference between the groups in the number of days on which extra medication was taken. A short, sharp course is of benefit physically, socially and psychologically to children with asthma.

Activities of Daily Living↗
PubMed1988

Effects of ageing and long-term subcultivation on collagen lattice contraction and intra-lattice proliferation in three rat cell types.

Many cells can contract a hydrated collagen lattice when seeded within one, reorganizing the collagen fibrils into a compact structure by tractional forces exerted during cell movement and translocation. The effects of ageing on this tractional-motility property of cells was examined for three cell types from adult Fischer 344 male rats: skin fibroblasts, aortic smooth muscle cells, and dedifferentiated chondrocytes. All cell types at low population doubling levels (PDL less than 10) contracted collagen lattices, though with different proficiencies (smooth muscle cells greater than dedifferentiated chondrocytes greater than skin fibroblasts). There was no significant difference in contraction ability of cell isolates of the same type obtained from 4-month and 24-30-month animals. Cells that had been subcultivated extensively (PDLs of 50-110) retained contractional ability. The cell types proliferated within lattices to varying extents, and there was no correlation between a cell type's extent of proliferation in a lattice and its proliferation in monolayer culture. That lattice contraction ability is preserved intact with ageing in three cell types suggests that the tractional forces exerted by cells on a collagen matrix in vitro may have a significant role in adult life in vivo.

Aging↗
PubMed1988

Policies: our footprints in the past, our signposts for the future.

Clearly established policies can guide our actions and activities and focus our attention. As our beliefs change so do our policies. It is the right as well as the responsibility of each of us as members of the American Occupational Therapy Association to watch for changes in our environment that might affect our thinking or our beliefs regarding our profession's role. Ideas for changes should be brought to the attention of the Representative Assembly, who will then be able to take action on possible policy changes. Our active involvement in this process will ensure that our policies are not just rigid, constraining dictums but are alive and changing with the times and truly reflect our footprints in the past and serve as our signposts for the future.

Certification↗